Name: characterization of metabolic status in nonhuman primates with the intravenous glucose tolerance test
Uploaded: 2016-11-13T13:00:00
Description: Watch this Scientific Journal Video about Characterization of Metabolic Status in Nonhuman Primates with the Intravenous Glucose Tolerance Test at JoVE.com

The authors would like to acknowledge the strong support of the DHMRI CLAS animal care staff, Facility Manager Mr. Daniel Peralta and attending veterinarian, Dr. Glicerio Ignacio, DVM MRCVS.

All animal procedures were approved by the David H. Murdock Research Institute IACUC located on the North Carolina Research Campus (NCRC), under protocol 14-017, Characterization of a nonhuman primate model of diabetes and prediabetes/insulin resistance and efficacy of therapeutics to improve insulin sensitivity and metabolic function.
1. Animal Selection and Study Preparation
<ol>
	<li>Select diet and weight stable animals based on monthly food intake and body weight records. 
	NOTE: A...

<ol>
	<li>Bergman, R., Phillips, L., Cobelli, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiologic+evaluation+of+factors+controlling+glucose+tolerance+in+man.">Physiologic evaluation of factors controlling glucose tolerance in man.</a> J. Clin. Invest. 68, 1456-1457 (1981).</li><li>Bergman, R., Prager, R., Volund, A., Olefsky, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Equivalence+of+the+insulin+sensitivity+index+in+man+derived+by+the+minimal+model+and+the+euglycemic+glucose+clamp.">Equivalence of the insulin sensitivity index in man derived by the minimal model and the euglycemic glucose clamp.</a> J. Clin. Invest. 79, 790-800 (1987).</li><li>Hovorka, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partitioning+glucose+distribution/transport,+disposal,+and+endogenous+production+during+IVGTT.">Partitioning glucose distribution/transport, disposal, and endogenous production during IVGTT.</a> Am. J. Physiol. Endocrinol. Metab. 282, E992-E1007 (2002).</li><li>Salinari, S., Guidone, C., Bertuzzi, A., Manco, M., Asnaghi, S., Mingrone, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=First-phase+insulin+secretion+restoration+and+differential+response+to+glucose+load+depending+on+the+route+of+administration+in+type+2+diabetic+subjects+after+beriatric+surgery.">First-phase insulin secretion restoration and differential response to glucose load depending on the route of administration in type 2 diabetic subjects after beriatric surgery.</a> Diabetes Care. 32 (3), 375-380 (2009).</li><li>Roden, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Clinical Diabetes Research: Methods and Techniques. , (2007).</li><li>Cobelli, C., Pacini, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+secretion+and+hepatic+extraction+in+humans+by+minimal+modeling+of+c-peptide+and+insulin+kinetics.">Insulin secretion and hepatic extraction in humans by minimal modeling of c-peptide and insulin kinetics.</a> Diabetes. 37, 223-231 (1988).</li><li>Lorenzo, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disposition+index,+glucose+effectiveness,+and+conversion+to+type+2+diabetes:+the+insulin+resistance+atherosclerosis+study.">Disposition index, glucose effectiveness, and conversion to type 2 diabetes: the insulin resistance atherosclerosis study.</a> Diabetes Care. 33, 2098-2103 (2010).</li><li>Hansen, B. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+and+treatment+of+type+2+diabetes+in+nonhuman+primates.">Investigation and treatment of type 2 diabetes in nonhuman primates.</a> Methods Mol Biol. 933, 177-185 (2012).</li><li>Hansen, B. C., Bodkin, N. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardization+of+IVGTT.+Importance+of+method+used+to+calculate+glucose+disappearance.">Standardization of IVGTT. Importance of method used to calculate glucose disappearance.</a> Diabetes Care. 16 (5), 847 (1993).</li><li>Hardwood, J. H., Listrani, P., Wagner, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonhuman+primates+and+other+animal+models+in+diabetes+research.">Nonhuman primates and other animal models in diabetes research.</a> J Diabetes Sci Tech. 3, 503-514 (2012).</li><li>De Koning, E. J., Bodkin, N. L., Hansen, B. C., Clark, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diabetes+mellitus+in+Macaca+mulatta+monkeys+is+characterized+by+islet+amyloidosis+and+reduction+in+beta-cell+population.">Diabetes mellitus in Macaca mulatta monkeys is characterized by islet amyloidosis and reduction in beta-cell population.</a> Diabetologia. 36, 378-384 (1993).</li><li>Letiexhe, M. R., Scheen, A. J., Gerard, P. L., Desaive, C., Lefebvre, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+secretion,+clearance+and+action+before+and+after+gastroplasty+in+severely+obese+subjects.">Insulin secretion, clearance and action before and after gastroplasty in severely obese subjects.</a> Int J Obes Relat Metab Disord. 18, 295-300 (1994).</li><li>Letiexhe, M. R., Scheen, A. J., Gerard, P. L., Desaive, C., Lefebvre, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postgastroplasty+recovery+of+ideal+body+weight+normalizes+glucose+and+insulin+metabolism+in+obese+women.">Postgastroplasty recovery of ideal body weight normalizes glucose and insulin metabolism in obese women.</a> J Clin Endocrinol Metab. 80, 364-369 (1995).</li><li>Kim, S. H., Abbasi, F., Chu, J. W., McLaughlin, T. L., Lamendola, C., Polonsky, K. S., Reaven, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rosiglitazone+reduces+glucose-stimulated+insulin+secretion+rate+and+increases+insulin+clearance+in+nondiabetic,+insulin-resistant+individuals.">Rosiglitazone reduces glucose-stimulated insulin secretion rate and increases insulin clearance in nondiabetic, insulin-resistant individuals.</a> Diabetes. 54, 2447-2452 (2005).</li><li>Toffolo, G., Breda, E., Cavaghan, M. K., Ehrmann, D. A., Polonsky, K. S., Cobelli, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+indexes+of+beta-cell+function+during+graded+up+and+down+glucose+infusion+from+C-peptide+minimal+models.">Quantitative indexes of beta-cell function during graded up and down glucose infusion from C-peptide minimal models.</a> Am J Physiol Endocrinol Metab. 280, E2-E10 (2001).</li><li>Wang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+beta-cell+insulin+secretory+function+using+a+graded+glucose-infusion+with+C-peptide+deconvolution+in+dysmetabolic,+and+diabetic+cynomolgus+monkeys.">Quantification of beta-cell insulin secretory function using a graded glucose-infusion with C-peptide deconvolution in dysmetabolic, and diabetic cynomolgus monkeys.</a> Diabetology and Metabolic Syn. 5, 40 (2013).</li><li>Xiao, Y. F., Wang, B., Wang, X., Du, F., Benzinou, M., Wang, Y. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xylazine-induced+reduction+of+tissue+sensitivity+to+insulin+leads+to+acute+hyperglycemia+in+diabetic+and+normoglycemic+monkeys.">Xylazine-induced reduction of tissue sensitivity to insulin leads to acute hyperglycemia in diabetic and normoglycemic monkeys.</a> Anesthesiology. 13 (33), (2013).</li><li>Porte, D., Kahn, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#946;-cell+dysfunction+and+failure+in+type+2+diabetes+potential+mechanisms.">&#946;-cell dysfunction and failure in type 2 diabetes potential mechanisms.</a> Diabetes. 50, S160-S163 (2001).</li><li>DeFronzo, R. A., Tobin, J. D., Andres, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucose+clamp+technique:+a+method+for+quantifying+insulin+secretion+and+resistance.">Glucose clamp technique: a method for quantifying insulin secretion and resistance.</a> American Journal of Physiology. 237 (3), G214-G223 (1979).</li><li>Ferrannini, E., Gastaldelli, A., Miyazaki, Y., Matsuda, M., Mari, A., DeFronzo, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#946;-cell+function+in+subjects+spanning+the+range+from+normal+glucose+tolerance+to+overt+diabetes:+a+new+analysis.">&#946;-cell function in subjects spanning the range from normal glucose tolerance to overt diabetes: a new analysis.</a> J Clin Endocrinol Metab. 90 (1), 493-500 (2005).</li><li>Vaughan, K. L., Szarowicz, M. D., Herbert, R. L., Mattison, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+anesthesia+protocols+for+intravenous+glucose+tolerance+testing+in+rhesus+monkeys.">Comparison of anesthesia protocols for intravenous glucose tolerance testing in rhesus monkeys.</a> J Med Primatol. 43, 162-168 (2014).</li><li>Kemnitz, J. W., Kraemer, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+glucoregulation+in+rhesus+monkeys+sedated+with+ketamine.">Assessment of glucoregulation in rhesus monkeys sedated with ketamine.</a> American Journal of Primatology. 3, 201-210 (1982).</li><li>Dutton, C. J., Parvin, C. A., Gronowski, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+glycated+hemoglobin+percentages+for+use+in+the+diagnosis+and+monitoring+of+diabetes+mellitus+in+nonhuman+primates.">Measurement of glycated hemoglobin percentages for use in the diagnosis and monitoring of diabetes mellitus in nonhuman primates.</a> Am J Vet Res. 64, 562-568 (2003).</li><li>Rai, V., Iyer, U., Mani, I., Mani, U. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+biochemical+changes+in+insulin+dependent+and+non-insulin+dependent+diabetes+mellitus+and+their+role+in+the+development+of+secondary+complications.">Serum biochemical changes in insulin dependent and non-insulin dependent diabetes mellitus and their role in the development of secondary complications.</a> Int J Diab Dev Countries. 17, 33-37 (1997).</li><li>Shirasaki, Y., Yoshioka, N., Kanazawa, K., Maekawa, T., Horikawa, T., Hayashi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+physical+restraint+on+glucose+tolerance+in+cynomolgus+monkeys.">Effect of physical restraint on glucose tolerance in cynomolgus monkeys.</a> J Med Primatol. 42, 165-168 (2013).</li></ol>

The IVGTT assesses the capacity of glucose-stimulated insulin release by a single dextrose infusion based on body weight 5, 12, 13. From the assay, the fasting blood glucose and insulin level is attained, and it allows an assessment of the animal&#39;s capacity to release insulin and return the elevated glucose level towards baseline. This provides the user with information to characterize the animal as a normal glucose and insulin level healthy control, a hyperinsulinemic dysmetabolic animal with normoglycemi...

The IVGTT is a convenient functional assay that is routinely used to determine the &#946;-cell function in humans at different metabolic states 5, 7. In animal models of T2D, it is well recognized as a tool to characterize animals that show metabolic disease progression from a healthy to a dysmetabolic hyperglycemic state 8, 9. The closest animal model of T2D is demonstrated in nonhuman primates (NHPs), of which rhesus and cynomolgus macaques are notable examples. These animals naturally develop T2D with the same risk factors of age and obesity contributing to its incidence as in humans 10. Furthermore, there is a similar disease progression and pancreatic pathology showing amyloid deposits as the dysmetabolic disease progresses 11.
Here we report on our standard method of performing an IVGTT in NHPs as part of our colony characterization of metabolic status in these animals. This method is easy to perform relative to other, more time consuming and costly techniques 2. The IVGTT is useful for characterizing a large colony of animals rapidly and frequently. When taken into consideration with the level of glycated hemoglobin (HbA1C), the animal&#39;s diet and food intake history, as well as their percent lean mass and body fat, the IVGTT is normally sufficient for characterizing an animal&#39;s metabolic status and progression toward overt diabetes 6, 8.
HbA1C represents the average glycemic level over the life of a red blood cell, providing a reliable measure of glucose levels over the previous six weeks to three months. When measured from the fasted baseline blood sample of the IVGTT, this value provides a window into glycemic control during the months between procedures. If the animal has transitioned from dysmetabolic to diabetic since their last IVGTT, an HbA1C value much higher than their previous value would indicate that the transition began soon after their last IVGTT, whereas, an HbA1C value closer to their previous value would indicate that they have only recently transitioned. In general, in rhesus macaques, HbA1C values greater than 6% are considered abnormal, and indicate poor glycemic control 10, 23.
Glycemic levels should be interpreted within the context of the behavior and general health of the animal as a whole. Diabetic macaques &#8212; like humans &#8212; exhibit hyperphagia, polydipsia, and polyuria. Group housing of animals provides significant challenges to measurement of these indicators and the individual care required for dysmetabolic and diabetic monkeys. We recommend singly housing the animals in order that more personalized care may be provided, and behavioral markers of the health of the monkey more easily be monitored 8. Additionally, diabetic macaques will exhibit weight loss, as well as an elevated lipid profile (increased cholesterol, hypertriglyceridemia) and disturbed mineral metabolism in serum chemistry. It is important to measure markers of liver and kidney function in serum chemistry, as damage to these organs are often complications of advancing metabolic disorder/diabetes, and may be co-determinants of glycemic, lipid and mineral imbalances 9, 11, 18, 24.
When using this method, the historic values generated from multiple, frequent characterizations over the life of a monkey are of particular value. If other procedures, such as a glucose clamp or graded glucose infusion (GGI), are needed to fully assess an animal&#39;s health, it is commonly upon initial characterization when their history is unavailable. However, once a baseline has been established, repeated IVGTTs of a frequency of every three months are normally sufficient to track an animal&#39;s progress. This is particularly important when the animals are enrolled into multiple studies throughout a calendar year based upon their metabolic status. While their health may remain relatively stable for years at a time, when the metabolic status of an animal worsens, a dramatic increase in insulin resistance and glucose intolerance can occur very rapidly. HbA1C values allow for some interpolation of the decline or improvement of the health status of the animal between procedures scheduled three months apart. For this reason, this method is ideal for characterizing animals used in multiple, longitudinal studies over the course of their natural lifespan.

<table border="0" cellpadding="0" cellspacing="0" width="670">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Allegra X-15R Centrifuge</td>
			<td style="width:147px;"></td>
			<td style="width:119px;"></td>
			<td style="width:188px;">plasma: 4C @3000 rpm for 10 min</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Sorvall ST16R Centrifuge</td>
			<td></td>
			<td style="width:119px;"></td>
			<td style="width:188px;">serum: 22C @3000 rpm for 10 min</td>
		</tr>
		<tr height="65">
			<td height="65" style="height:65px;width:216px;">Thermo Scientific -86C Freezer, Forma 88000 Series</td>
			<td></td>
			<td>Model: 88500A</td>
			<td style="width:188px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dextrose 50% (D50)</td>
			<td style="width:147px;">Webster</td>
			<td style="width:119px;">07-8008986</td>
			<td style="width:188px;">I.V. glucose infusate</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">3mL Luer Lock Syringe</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;"></td>
			<td style="width:188px;">serial blood draws</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">5ml Luer Lock Syringe</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;"></td>
			<td style="width:188px;">heparinized saline flush</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">10mL Luer Lock Syringe</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;"></td>
			<td style="width:188px;">delivery of I.V. D50</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Gauze sponges 2x2</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;">366.23000.4</td>
			<td style="width:188px;">Used Dry, w/ %70 Alcohol, and 2% Chlorohex Solution</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">4 ml serum separator tubes&#160;</td>
			<td style="width:147px;">Midwest Veterinary Supply</td>
			<td style="width:119px;">366.45000.4</td>
			<td style="width:188px;">blood collection tube for superchem panel</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">K2EDTA, 2mL</td>
			<td style="width:147px;">VWR</td>
			<td style="width:119px;">95057-239</td>
			<td style="width:188px;">blood collection tubes</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Aprotinin, 100mg</td>
			<td style="width:147px;">Sigma</td>
			<td style="width:119px;">A1153-100MG</td>
			<td style="width:188px;">blood collection tube protease additive</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">22g x 1&#34; Catheters</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;">193.75250.2</td>
			<td style="width:188px;">I.V. catheter&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Injection Plug W/ Cap</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;">001.11500.2</td>
			<td style="width:188px;">%50 dextrose infusion port</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Porus Tape, 1/2&#34; x 10yd&#160;</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;">001.85000.2</td>
			<td style="width:188px;">maintain adherance of catheters and hep. Locks</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Chlorhexidine Solution 2%</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;">193.08855.3</td>
			<td style="width:188px;">prep catheter site</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">70% Ethanol</td>
			<td style="width:147px;">VWR</td>
			<td style="width:119px;">71001-654</td>
			<td style="width:188px;">prep catheter site</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">tourniquet</td>
			<td style="width:147px;">Webster</td>
			<td style="width:119px;">07-8003432</td>
			<td style="width:188px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">3 way stopcock</td>
			<td style="width:147px;">Midwest Veterinary Supply</td>
			<td style="width:119px;">366.28510.4</td>
			<td style="width:188px;">hep. lock</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">37&#34; extension set</td>
			<td style="width:147px;">Webster</td>
			<td style="width:119px;">07-8454200</td>
			<td style="width:188px;">hep. lock</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Exel 50-60cc LL Syringes</td>
			<td style="width:147px;">Midwest Veterinary Suppy</td>
			<td style="width:119px;">001.12250.2</td>
			<td style="width:188px;">Heparinized saline flush</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">250 ml bag 0.9% saline</td>
			<td style="width:147px;">Webster</td>
			<td style="width:119px;">07-8365593</td>
			<td style="width:188px;">flush</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1,000 U Heparin, 10 ml</td>
			<td style="width:147px;">Webster</td>
			<td style="width:119px;">07-883-4916</td>
			<td style="width:188px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ketamine, (Ketaset) 100mg/mL</td>
			<td style="width:147px;">Fort Dodge</td>
			<td style="width:119px;">(AV ordered)</td>
			<td style="width:188px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Precision Xtra glucose test strips 50/bx</td>
			<td style="width:147px;">Abbott (American Diabetes Wholesale)</td>
			<td style="width:119px;">9381599728K7</td>
			<td style="width:188px;">test baseline/ T3 blood glucose levels</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Masimo Rad 57</td>
			<td style="width:147px;">DRE</td>
			<td style="width:119px;">6052057V</td>
			<td style="width:188px;">pulse-oximeter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pavia rectal thermometer</td>
			<td style="width:147px;">Patterson</td>
			<td style="width:119px;">07-8391335</td>
			<td style="width:188px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Precision Xtra Glucometer</td>
			<td style="width:147px;">Abbott</td>
			<td style="width:119px;">9381599728K7</td>
			<td style="width:188px;">Handheld glucometer</td>
		</tr>
	</tbody>
</table>

characterization of metabolic status in nonhuman primates with the intravenous glucose tolerance test

The intravenous glucose tolerance test (IVGTT) plays a key role in the characterization of glucose homeostasis. When taken together with serum biochemical profiles, inclusive of blood glucose levels in both the fed and fasted state, HbA1c, insulin levels, clinical history of diet, body composition, and body weight status, an assessment of normal and abnormal glycemic control can be made. Interpretation of an IVGTT is done through measurement of changes in glucose and insulin levels over time in relation to the dextrose challenge. Critical components to be considered are: peak glucose and insulin levels reached in relation to T0 (end of glucose infusion), the glucose clearance rate K derived from the slope of rapid glucose clearance in the first 20 min (T1 to T20), the time to return to glucose baseline, and the area under the curve (AUC). These IVGTT measures will show characteristic changes as glucose homeostasis moves from a healthy to a diseased metabolic state5. Herein we will describe the characterization of nonhuman primates (Rhesus and Cynomolgus macaques), which are the most relevant animal model of Type II diabetes (T2D) in humans and the IVGTT and clinical profiles of these animals from a lean healthy, to obese dysmetabolic, and T2D state 8, 10, 11.

The results shown in Figure 1 are demonstrative of typical glucose and insulin curves from mature, healthy and diabetic cynomolgus macaques over the course of a 30 min IVGTT. Data from healthy and advanced diabetic monkeys are shown in order to contrast the obvious differences between animals from both extreme ends of the range of metabolic characterization. This IVGTT protocol has been used successfully by the authors in rhesus macaques with similar results.
<p class...

Watch this Scientific Journal Video about Characterization of Metabolic Status in Nonhuman Primates with the Intravenous Glucose Tolerance Test at JoVE.com

Characterization of Metabolic Status in Nonhuman Primates with the Intravenous Glucose Tolerance Test

The goal of this protocol is to present a standard method to perform intravenous glucose tolerance tests (IVGTTs) to assess glycemic control in nonhuman primates and assess their metabolic status from healthy to dysmetabolic.

The intravenous glucose tolerance test (IVGTT) plays a key role in the characterization of glucose homeostasis. When taken together with serum biochemical ...

The overall goal of this intravenous glucose tolerance test, or IVGTT, is to characterize the progression of metabolic disease in macaques, from a healthy to a dismetabolic, hyperglycemic state. This method can be used to establish cohorts of subjects stratified by their metabolic status for dietary or pharmacological investigation of the therapeutic efficacy of treatments for insulin resistance in diabetes. The main advantage of this technique is that it is easy to perform relative to other more time consuming and costly techniques.14 to 18 hours before beginning the procedure, remove the food from the macaque's cage to avoid any post-prandial variegation in the glycemic values. The next morning, weigh the sedated animal. Then place the primate in a laterally recumbent position on a heated procedure table.Every 15 to 20 minutes, use a pulse oximeter to measure the heart rate and peripheral capillary oxygen saturation. Use a stop watch to measure the respiratory rate, and a thermometer to measure the temperature rectally. Confirm that the mucous membrane around the gum and lips is moist and pink at every clinic parameter check as well.After confirming the baseline health of the animal, use clippers to trim the hair from the areas where the catheters will be inserted, followed by the sterilization of both regions with alternating scrubs of chlorhexidine and 70%alcohol. When the sites are ready, insert the first catheter and attach the lure to a heparin-saline flush with a three-way stopcock. This is the sampling blood draw site.Tape the stopcock to secure it to the leg. The placement of the catheter is critical for patency and precise serial blood draws. Therefore, it is important to consider a medial and more proximal region of the saphenous vein to easily secure and manipulate the heparinized flush in-lock system.Then, place the second catheter, and attach a port for the dextrose infusion, followed by the administration of a one millilitre flush of heparinized saline to keep the cannula patent until the dextrose infusion. Tape the port to the arm to secure it. When both of the catheters are in place, obtain a baseline sample, and use a handheld glucometer to measure the fasting blood glucose level.Secure a serum sample for the standard chemistry analysis, as well as a whole blood sample for a complete blood cell count to assess the overall health of the animal. Invert the whole blood sample. After each blood draw, mix the samples in EDTA tubes with the protease inhibitors.After obtaining the baseline samples, infuse the 50%dextrose dose over 30 seconds via the dextrose infusion port. Then, flush with five milliliters of heparinized saline, so that no dextrose is left in the port. At the end of the infusion, change gloves, as residual dextrose from the infusion may contaminate the subsequent blood samples.The first post-infusion sample time point is at time three minutes from the end of the dextrose infusion, followed by samples at T five, seven, 10, 15, and 20 minutes, with the last sample obtained at T 30 minutes. Centrifuge the samples for glucose and insulin analysis within 10 minutes of collection, then aliquot the plasma into cryovials for freezing and storage at negative 80 degrees Celsius, until downstream analysis of the samples. At the T three sample draw, use the handheld glucometer to check the blood glucose level for confirmation of the dextrose infusion.When the last sample has been collected, remove the cannulas, applying pressure to the catheterized sites for hemostasis, and monitor the animal until it is fully recovered. Here, typical glucose and insulin curves from mature, healthy and diabetic cynomolgus macaques over the course of a 30 minute IVGTT are shown. The fasted baseline glucose values of healthy macaques can be as low as 50 to 60 milligrams per deciliter, with an initial plasma glucose spike observed at the T three minute time point.That is dramatically lower than the typical plasma glucose spike exhibited by diabetic animals. Over the course of the procedure, the glucose levels of healthy animals often return to their baseline values, while dismetabolic and diabetic animal levels do not. The accompanying insulin curve for a healthy animal exhibits two peaks, corresponding to an initial rapid decline in blood glucose mediated in larger than normal part by the peripheral effects of insulin on glucose transport and uptake.The magnitude of these peripheral effects, even during the first phase of the insulin response, does not equal the contribution of the liver to glucose lowering, which, during the smaller but more sustained second insulin peak, has the greatest impact on glycemic levels via the suppression of endogenous glucose production. Once an animal has become overly diabetic, insulin production in response to the dextrose bolus drops dramatically. Glycemic levels will remain elevated over the course of the procedure.As with glucose, clearance occurs is now mediated almost entirely by non-insulin dependent mechanisms. Following this procedure, other methods like graded glucose infusion, or the hyperinsulinemic euglycemic clamp can be performed to answer additional questions about insulin sensitivity. Don't forget that working with needles exposed to macaque blood can be extremely hazardous, due to the potential for exposure to herpes B virus.Precautions, such as wearing the proper personal protective gear, and taking extreme care when handling sharps should always be observed while performing this procedure.

characterization-metabolic-status-nonhuman-primates-with-intravenous

Research

JoVE Journal

Medicine

Making Sense of Listening: The IMAP Test Battery

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the abilities to extract and use the information encoded in the auditory signal. We refer to these as listening skills (or auditory processing AP). Deficits in these skills are associated with delayed language and literacy development, though the nature of the relevant deficits and their causal connection with these delays is hotly debated.
When a child is referred to a health professional with normal hearing and unexplained difficulties in listening, or associated delays in language or literacy development, they should ideally be assessed with a combination of psychoacoustic (AP) tests, suitable for children and for use in a clinic, together with cognitive tests to measure attention, working memory, IQ, and language skills. Such a detailed examination needs to be relatively short and within the technical capability of any suitably qualified professional. Current tests for the presence of AP deficits tend to be poorly constructed and inadequately validated within the normal population. They have little or no reference to the presenting symptoms of the child, and typically include a linguistic component. Poor performance may thus reflect problems with language rather than with AP. To assist in the assessment of children with listening difficulties, pediatric audiologists need a single, standardized child-appropriate test battery based on the use of language-free stimuli.
We present the IMAP test battery which was developed at the MRC Institute of Hearing Research to supplement tests currently used to investigate cases of suspected AP deficits. IMAP assesses a range of relevant auditory and cognitive skills and takes about one hour to complete. It has been standardized in 1500 normally-hearing children from across the UK, aged 6-11 years. Since its development, it has been successfully used in a number of large scale studies both in the UK and the USA. IMAP provides measures for separating out sensory from cognitive contributions to hearing. It further limits confounds due to procedural effects by presenting tests in a child-friendly game-format. Stimulus-generation, management of test protocols and control of test presentation is mediated by the IHR-STAR software platform. This provides a standardized methodology for a range of applications and ensures replicable procedures across testers. IHR-STAR provides a flexible, user-programmable environment that currently has additional applications for hearing screening, mapping cochlear implant electrodes, and academic research or teaching.

A test battery (IMAP) for performing an in-depth assessment of auditory and cognitive abilities contributing to listening skills is described. It is quick to administer, child-friendly and free from linguistic confounds. Stimulus generation and protocol management are controlled via a software platform (IHR-STAR) to ensure replicable procedures.

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the ...

Delivery of Therapeutic Agents Through Intracerebroventricular (ICV) and Intravenous (IV) Injection in Mice

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most often results in failure of potential therapeutics designed for neurodegenerative disorders 1,2. Neurodegenerative diseases such as Spinal Muscular Atrophy (SMA), in which the lower motor neurons are affected, can benefit greatly from introducing the therapeutic agents into the CNS. The purpose of this video is to demonstrate two different injection paradigms to deliver therapeutic materials into neonatal mice soon after birth. One of these methods is injecting directly into cerebral lateral ventricles (Intracerebroventricular) which results in delivery of materials into the CNS through the cerebrospinal fluid 3,4. The second method is a temporal vein injection (intravenous) that can introduce different therapeutics into the circulatory system, leading to systemic delivery including the CNS 5. Widespread transduction of the CNS is achievable if an appropriate viral vector and viral serotype is utilized. Visualization and utilization of the temporal vein for injection is feasible up to postnatal day 6. However, if the delivered material is intended to reach the CNS, these injections should take place while the blood brain barrier is more permeable due to its immature status, preferably prior to postnatal day 2. The fully developed blood brain barrier greatly limits the effectiveness of intravenous delivery. Both delivery systems are simple and effective once the surgical aptitude is achieved. They do not require any extensive surgical devices and can be performed by a single person. However, these techniques are not without challenges. The small size of postnatal day 2 pups and the subsequent small target areas can make the injections difficult to perform and initially challenging to replicate.

Delivery of Therapeutic Agents Through Intracerebroventricular ICV and Intravenous IV Injection in Mice

This article demonstrates two very different methods of injection: 1) into the brain (intracerebroventricular) and 2) systemic (intravenous) to introduce the therapeutic agents into the central nervous system of neonatal mice.

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most ...

Tilt Testing with Combined Lower Body Negative Pressure: a "Gold Standard" for Measuring Orthostatic Tolerance

Orthostatic tolerance (OT) refers to the ability to maintain cardiovascular stability when upright, against the hydrostatic effects of gravity, and hence to maintain cerebral perfusion and prevent syncope (fainting). Various techniques are available to assess OT and the effects of gravitational stress upon the circulation, typically by reproducing a presyncopal event (near-fainting episode) in a controlled laboratory environment. The time and/or degree of stress required to provoke this response provides the measure of OT. Any technique used to determine OT should: enable distinction between patients with orthostatic intolerance (of various causes) and asymptomatic control subjects; be highly reproducible, enabling evaluation of therapeutic interventions; avoid invasive procedures, which are known to impair OT1.
In the late 1980s head-upright tilt testing was first utilized for diagnosing syncope2. Since then it has been used to assess OT in patients with syncope of unknown cause, as well as in healthy subjects to study postural cardiovascular reflexes2-6. Tilting protocols comprise three categories: passive tilt; passive tilt accompanied by pharmacological provocation; and passive tilt with combined lower body negative pressure (LBNP). However, the effects of tilt testing (and other orthostatic stress testing modalities) are often poorly reproducible, with low sensitivity and specificity to diagnose orthostatic intolerance7.
Typically, a passive tilt includes 20-60 min of orthostatic stress continued until the onset of presyncope in patients2-6. However, the main drawback of this procedure is its inability to invoke presyncope in all individuals undergoing the test, and corresponding low sensitivity8,9. Thus, different methods were explored to increase the orthostatic stress and improve sensitivity.
Pharmacological provocation has been used to increase the orthostatic challenge, for example using isoprenaline4,7,10,11 or sublingual nitrate12,13. However, the main drawback of these approaches are increases in sensitivity at the cost of unacceptable decreases in specificity10,14, with a high positive response rate immediately after administration15. Furthermore, invasive procedures associated with some pharmacological provocations greatly increase the false positive rate1.
Another approach is to combine passive tilt testing with LBNP, providing a stronger orthostatic stress without invasive procedures or drug side-effects, using the technique pioneered by Professor Roger Hainsworth in the 1990s16-18. This approach provokes presyncope in almost all subjects (allowing for symptom recognition in patients with syncope), while discriminating between patients with syncope and healthy controls, with a specificity of 92%, sensitivity of 85%, and repeatability of 1.1&plusmn;0.6 min16,17. This allows not only diagnosis and pathophysiological assessment19-22, but also the evaluation of treatments for orthostatic intolerance due to its high repeatability23-30. For these reasons, we argue this should be the "gold standard" for orthostatic stress testing, and accordingly this will be the method described in this paper.

We describe a "gold standard" for evaluating orthostatic tolerance (OT) using tilt testing with combined lower body negative pressure (LBNP). This can be combined with non-invasive evaluations of cardiovascular reflex control. Normal and abnormal responses are defined.

Orthostatic tolerance (OT)  refers to the ability to maintain cardiovascular stability when upright,  against the hydrostatic effects of gravity, and ...

Improving Strength, Power, Muscle Aerobic Capacity, and Glucose Tolerance through Short-term Progressive Strength Training Among Elderly People

This protocol describes the simultaneous use of a broad span of methods to examine muscle aerobic capacity, glucose tolerance, strength, and power in elderly people performing short-term resistance training (RET). Supervised progressive resistance training for 1 h three times a week over 8 weeks was performed by RET participants (71&#177;1 years, range 65-80). Compared to a control group without training, the RET showed improvements on the measures used to indicate strength, power, glucose tolerance, and several parameters of muscle aerobic capacity. Strength training was performed in a gym with only robust fitness equipment. An isokinetic dynamometer for knee extensor strength permitted the measurement of concentric, eccentric, and static strength, which increased for the RET group (8-12% post- versus pre-test). The power (rate of force development, RFD) at the initial 0-30 ms also showed an increase for the RET group (52%). A glucose tolerance test with frequent blood glucose measurements showed improvements only for the RET group in terms of blood glucose values after 2 h (14%) and the area under the curve (21%). The blood lipid profile also improved (8%). From muscle biopsy samples prepared using histochemistry, the amount of fiber type IIa increased, and a trend towards a decrease in IIx in the RET group reflected a change to a more oxidative profile in terms of fiber composition. Western blot (to determine the protein content related to the signaling for muscle protein synthesis) showed a rise of 69% in both Akt and mTOR in the RET group; this also showed an increase in mitochondrial proteins for OXPHOS complex II and citrate synthase (both ~30%) and for complex IV (90%), in only the RET group. We demonstrate that this type of progressive resistance training offers various improvements (e.g., strength, power, aerobic capacity, glucose tolerance, and plasma lipid profile).

The effect of short-term resistance training on elderly people was investigated through the simultaneous use of several methods. Compared to a control group, many improvements were seen, including on muscle aerobic capacity, glucose tolerance, strength, power, and muscle quality (i.e., protein involved in cell signaling and muscle fiber type composition).

This protocol describes the simultaneous use of a broad span of methods to examine muscle aerobic capacity, glucose tolerance, strength, and power in ...

Studying the Hypothalamic Insulin Signal to Peripheral Glucose Intolerance with a Continuous Drug Infusion System into the Mouse Brain

Insulin regulates systematic metabolism in the hypothalamus and the peripheral insulin response. An inflammatory reaction in peripheral adipose tissues contributes to type 2 diabetes mellitus (T2DM) development and appetite regulation in the hypothalamus. Chemokine CCL5 and C-C chemokine receptor type 5 (CCR5) levels have been suggested to mediate arteriosclerosis and glucose intolerance in type 2 diabetes mellitus (T2DM). In addition, CCL5 plays a neuroendocrine role in the hypothalamus by regulating food intake and body temperature, thus, prompting us to investigate its function in hypothalamic insulin signaling and the regulation of peripheral glucose metabolism.
The micro-osmotic pump brain infusion system is a quick and precise way to manipulate CCL5 function and study its effect in the brain. It also provides a convenient alternative approach to generating a transgenic knockout animal. In this system, CCL5 signaling was blocked by intracerebroventricular (ICV) infusion of its antagonist, MetCCL5, using a micro-osmotic pump. The peripheral glucose metabolism and insulin responsiveness was detected by the Oral Glucose Tolerance Test (OGTT) and Insulin Tolerance Test (ITT). Insulin signaling activity was then analyzed by protein blot from tissue samples derived from the animals.
After 7-14 days of MetCCL5 infusion, the glucose metabolism and insulin responsiveness was impaired in mice, as seen in the results of the OGTT and ITT. The IRS-1 serine302 phosphorylation was increased and the Akt activity was reduced in mice hypothalamic neurons following CCL5 inhibition. Altogether, our data suggest that blocking CCL5 in the mouse brain increases the phosphorylation of IRS-1 S302 and interrupts hypothalamic insulin signaling, leading to a decrease in insulin function in peripheral tissues as well as the impairment of glucose metabolism.

This protocol studies the role of chemokine (C-C motif) ligand 5 (CCL5) in the hypothalamus by delivering an antagonist, MetCCL5, into the mouse brain using a micro-osmotic pump brain infusion system. This transient inhibition of CCL5 activity interrupted hypothalamic insulin signaling, leading to glucose intolerance and peripheral systemic insulin sensitivity.

Insulin regulates systematic metabolism in the hypothalamus and the peripheral insulin response. An inflammatory reaction in peripheral adipose tissues ...

Study of In Vivo Glucose Metabolism in High-fat Diet-fed Mice Using Oral Glucose Tolerance Test (OGTT) and Insulin Tolerance Test (ITT)

Obesity represents the most important single risk factor in the pathogenesis of type 2 diabetes, a disease which is characterized by a resistance to insulin-stimulated glucose uptake and a gross decompensation of systemic glucose metabolism. Despite considerable progress in the understanding of glucose metabolism, the molecular mechanisms of its regulation in health and disease remain under-investigated, while novel approaches to prevent and treat diabetes are urgently needed. Diet derived glucose stimulates the pancreatic secretion of insulin, which serves as the principal regulator of cellular anabolic processes during the fed-state and thus balances blood glucose levels to maintain systemic energy status. Chronic overfeeding triggers meta-inflammation, which leads to alterations in peripheral insulin receptor-associated signaling and thus reduces the sensitivity to insulin-mediated glucose disposal. These events ultimately result in elevated fasting glucose and insulin levels as well as a reduction in glucose tolerance, which in turn serve as important indicators of insulin resistance. Here, we present a protocol for the generation and metabolic characterization of high-fat diet (HFD)-fed mice as a frequently used model of diet-induced insulin resistance. We illustrate in detail the oral glucose tolerance test (OGTT), which monitors the peripheral disposal of an orally administered glucose load and insulin secretion over time. Additionally, we present a protocol for the insulin tolerance test (ITT) to monitor whole-body insulin action. Together, these methods and their downstream applications represent powerful tools to characterize the general metabolic phenotype of mice as well as to specifically assess alterations in glucose metabolism. They may be especially useful in the broad research field of insulin resistance, diabetes and obesity to provide a better understanding of pathogenesis as well as to test the effects of therapeutic interventions.

Study of In Vivo Glucose Metabolism in High-fat Diet-fed Mice Using Oral Glucose Tolerance Test OGTT and Insulin Tolerance Test ITT

The current article describes the generation and metabolic characterization of high-fat diet-fed mice as a model of diet-induced insulin resistance and obesity. It further features detailed protocols to perform the oral glucose tolerance test and the insulin tolerance test, monitoring whole-body alterations of glucose metabolism in vivo.

Obesity represents the most important single risk factor in the pathogenesis of type 2 diabetes, a disease which is characterized by a resistance to ...

Mechanisms Underlying Gut Hormone Secretion Using the Isolated Perfused Rat Small Intestine

The gut is the largest endocrine organ of the body, producing more than 15 different peptide hormones that regulate appetite and food intake, digestion, nutrient absorption and distribution, and post-prandial glucose excursions. Understanding the molecular mechanisms that regulate gut hormone secretion is fundamental for understanding and translating gut hormone physiology. Traditionally, the mechanisms underlying gut hormone secretion are either studied in vivo (in experimental animals or humans) or using gut hormone-secreting primary mucosal cell cultures or cell lines. Here, we introduce an isolated perfused rat small intestine as an alternative method for studying gut hormone secretion. The virtues of this model are that it relies on the intact gut, meaning that it recapitulates most of the physiologically important parameters responsible for the secretion in in vivo studies, including mucosal polarization, paracrine relationships and routes of perfusion/stimulus exposure. In addition, and unlike in vivo studies, the isolated perfused rat small intestine allows for almost complete experimental control and direct assessment of secretion. In contrast to in vitro studies, it is possible to study both the magnitude and the dynamics of secretion and to address important questions, such as what stimuli cause secretion of different gut hormones, from which side of the gut (luminal or vascular) is secretion stimulated, and to analyze in detail molecular sensors underlying the secretory response. In addition, the preparation is a powerful model for the study of intestinal absorption and details regarding the dynamics of intestinal absorption including the responsible transporters.

Here, we present a powerful and physiological model to study the molecular mechanisms underlying gut hormone secretion and intestinal absorption &#8212; the isolated perfused rat small intestine.

The gut is the largest endocrine organ of the body, producing more than 15 different peptide hormones that regulate appetite and food intake, digestion, ...

Assessment and Characterization of Hyaloid Vessels in Mice

In the eye, the embryonic hyaloid vessels nourish the developing lens and retina and regress when the retinal vessels develop. Persistent or failed regression of hyaloid vessels can be seen in diseases such as persistent hyperplastic primary vitreous (PHPV), leading to an obstructed light path and impaired visual function. Understanding the mechanisms underlying the hyaloid vessel regression may lead to new molecular insights into the vascular regression process and potential new ways to manage diseases with persistent hyaloid vessels. Here we describe the procedures for imaging hyaloid in live mice with optical coherence tomography (OCT) and fundus fluorescein angiography (FFA) and a detailed technical protocol of isolating and flat-mounting hyaloid ex vivo for quantitative analysis. Low-density lipoprotein receptor-related protein 5 (LRP5) knockout mice were used as an experimental model of persistent hyaloid vessels, to illustrate the techniques. Together, these techniques may facilitate a thorough assessment of hyaloid vessels as an experimental model of vascular regression and studies on the mechanism of persistent hyaloid vessels.

This protocol describes both in vivo and ex vivo methods to fully visualize and characterize hyaloid vessels, a model of vascular regression in mouse eyes, using optical coherence tomography and fundus fluorescein angiography for the live imaging and ex vivo isolation and subsequent flat mount of hyaloid for quantitative analysis.

In the eye, the embryonic hyaloid vessels nourish the developing lens and retina and regress when the retinal vessels develop. Persistent or failed ...

Transthoracic Echocardiographic Examination in the Rabbit Model

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to that of humans and that of other large animal models such as dogs and pigs. However, the rabbit model has the additional advantage of lower maintenance costs compared to other large animal models. The longitudinal evaluation of cardiac function using echocardiography, when appropriately implemented, is a useful methodology for preclinical assessment of novel therapies for heart failure with reduced ejection fraction (e.g. cardiac regeneration). The correct use of this non-invasive tool requires the implementation of a standardized examination protocol following international guidelines. Here we describe, step by step, a detailed protocol supervised by veterinary cardiologists for performing echocardiography in the rabbit model, and demonstrate how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Here we describe, step by step, a detailed protocol for performing echocardiography in the rabbit model. We show how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to ...

Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans

In mammals, brown adipose tissue (BAT) is activated rapidly in response to cold in order to maintain body temperature. Although BAT has been studied greatly in small animals, it is difficult to measure the activity of BAT in humans. Therefore, little is known about the heat-generating capacity and physiological significance of BAT in humans, including the degree to which components of the diet can activate BAT. This is due to the limitations in the currently most used method to assess the activation of BAT-radiolabeled glucose (fluorodeoxyglucose or 18FDG) measured by positron emission tomography-computerized tomography (PET-CT).
This method is usually performed in fasted subjects, as feeding induces glucose uptake by the muscles, which can mask the glucose uptake into the BAT. This paper describes a detailed protocol for quantifying total-body human energy expenditure and substrate utilization from BAT thermogenesis by combining indirect calorimetry, infrared thermography, and blood glucose monitoring in carbohydrate-loaded adult males. To characterize the physiological significance of BAT, measures of the impact of BAT activity on human health are critical. We demonstrate a protocol to achieve this by combining carbohydrate loading and indirect calorimetry with measurements of supraclavicular changes in temperature. This novel approach will help to understand the physiology and pharmacology of BAT thermogenesis in humans.

Here, we present a protocol to quantify the physiological significance of the impact of brown adipose tissue (BAT) activity on human metabolism. This is achieved by combining carbohydrate loading and indirect calorimetry with measurements of supraclavicular changes in temperature. This novel approach can help develop a pharmacological target for BAT thermogenesis in humans.

In mammals, brown adipose tissue (BAT) is activated rapidly in response to cold in order to maintain body temperature. Although BAT has been studied ...