Name: a rapid method for blood processing to increase the yield of plasma peptide levels in human blood
Uploaded: 2016-04-28T15:00:00
Description: Watch this Scientific Journal Video about A RAPID Method for Blood Processing to Increase the Yield of Plasma Peptide Levels in Human Blood at JoVE.com

This work was supported by German Research Foundation STE 1765/3-1 (A.S.) and German Ministry for Education and Research 03IPT614A (C.G.). We thank Reinhard Lommel and Petra Bu&#223;e for their excellent technical support as well as Karin Johansson and Christina Hentzschel for help with organization and execution of anthropometric measurements

The protocol was approved by the local ethics committee for human research (protocol number EA1/114/10).
1. Blood Processing
<ol>
	<li>Collect venous blood between 07:00 and 08:00 am after an overnight fast from a forearm vein and process according to standard procedure or the RAPID method. Instruct the subjects to not exercise or smoke before blood withdrawal.</li>
	<li>For standard processing, collect blood in chilled EDTA-containing tubes and centrifuge within 10 min at 3,000 x g for 10 min at 4 &#176;C. Coll...

<ol>
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We reported before that the RAPID method for blood processing improved the recovery for 11/12 peptides compared to standard blood processing in rats6. In the present study we have shown that this method is also suited for the use in humans. Following RAPID processing, the recovery for 9 of 9 125I-labeled peptides tested was improved compared to standard blood processing (EDTA blood on ice). The observed improvement ranged from 19-39% which is likely to be relevant, especially under conditions when o...

In light of the worldwide increasing prevalence of obesity1,2, research in the field of food intake regulation is gaining importance. While so far only one peptide is known that is peripherally produced and centrally acting to stimulate food intake, namely ghrelin3, within the past decades, a broad range of peptides has been identified that reduce food intake, e.g. leptin, peptide YY (PYY) and also glucagon-like peptide-1 (GLP-1) and insulin4, Therefore, in studies investigating the regulatory mechanisms of hunger and satiety peptide levels are often assessed and at the same time, it is assumed that the peptide studied is stable and recovered at high yields during plasma formation. However, very often this is not the case due to rapid endogenous breakdown as shown before for e.g. ghrelin which is degraded from acyl to desacyl ghrelin5. Therefore, we recently described the RAPID method for blood processing in rats employing Reduced temperatures, Acidification, Protease inhibition, Isotopic exogenous controls and Dilution6. This method improved the recovery for 11 of 12 peptides tested and allowed for the determination of the correct circulating molecular form compared to standard blood processing (EDTA blood on ice)6. This method has been used in several subsequent studies7-12 for the detection of circulating ghrelin as well as corticotropin-releasing factor13. Therefore, the method has proven useful for peptide research in rodents. However, since rodent studies are not always translatable to another species, the method should be established for the use in human blood as well.
The aim of the present study was to test the RAPID method for blood processing in humans compared to standard blood processing, EDTA blood on ice, which is widely recommended14 and frequently used in the clinical as well as research setting. We tested the recovery of a selection of 125I-labeled peptides involved in the regulation of food intake including established peptides as well as new candidates recently suggested to play a role in feeding regulation (effects on food intake are shown in Table 1) following processing with both methods. Hormones were also chosen to represent peptides of different length and charge (Table 2). Moreover, for ghrelin we investigated the molecular form(s) following the standard and RAPID method. Lastly, we assessed endogenous ghrelin (acyl and desacyl ghrelin) as well as kisspeptin levels, a peptide also recently suggested to play a role in the regulation of food intake15,16 following RAPID or standard processing. In addition, we also investigated these peptide levels in a population of subjects with a wide range of body mass index (ranging from 10.2-67.6 kg/m2) to study possible differences related to chronically altered body weight.
<img alt="Table 1" src="/files/ftp_upload/53959/53959table1.jpg" />
<img alt="Table 2" src="/files/ftp_upload/53959/53959table2.jpg" />
Diagnosis, Assessment, and Plan: 
Study participants 
All study participants were newly hospitalized patients (inclusion was within two days of admission to the hospital) of the Division of Psychosomatic Medicine at Charit&#233;-Universit&#228;tsmedizin Berlin and gave written informed consent. To avoid any impact of gender only female patients were included. A total of 42 subjects participated in this study and were divided into three groups: normal weight (BMI 18.5-25 kg/m2, n = 12), anorexia nervosa (BMI &#60;17.5 kg/m2, n = 15) and obesity (BMI &#62;30 kg/m2, n = 15). Anorexic and obese patients were diagnosed according to the International Classification of Diseases-10 and hospitalized for weight gain (anorexia nervosa) or weight reduction (obesity), respectively. All normal weight patients were hospitalized exclusively due to somatoform symptoms without relevant somatic disorders. Patients with gastrointestinal somatoform symptoms or a history of gastrointestinal surgery were excluded. Exclusion criteria also encompassed an age &#60;18 years, current pregnancy and untreated psychotic diseases. Blood collection was performed on day 2 or 3 after hospital admission before receiving dietary treatment in order to increase or reduce body weight, respectively. Anthropometric parameters were assessed on the same day.

<table border="0" cellpadding="0" cellspacing="0" width="1268">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">diprotin A</td>
			<td style="width:351px;">Peptides International, Louisville, KY, USA</td>
			<td style="width:119px;">IDP-4132</td>
			<td style="width:456px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">E-64-d</td>
			<td>Peptides International, Louisville, KY, USA</td>
			<td style="width:119px;">IED-4321-v</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">antipain</td>
			<td>Peptides International, Louisville, KY, USA</td>
			<td style="width:119px;">IAP-4062</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">leupeptin</td>
			<td>Peptides International, Louisville, KY, USA</td>
			<td style="width:119px;">ILP-4041</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">chymostatin</td>
			<td>Peptides International, Louisville, KY, USA</td>
			<td style="width:119px;">ICY-4063</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sep-Pak C18 cartridges</td>
			<td>Waters Corporation, Milford, MA, USA</td>
			<td>WAT051910</td>
			<td>360 mg, 55-105 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">acyl-ghrelin</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td style="width:119px;">9088-HK</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GLP-1</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td style="width:119px;">9035-HK</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">glucagon</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td style="width:119px;">9030</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">insulin</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td style="width:119px;">9011S</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">leptin</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td style="width:119px;">9081-HK</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">kisspeptin-10</td>
			<td>Phoenix Pharmaceuticals, Burlingame, CA, USA</td>
			<td style="width:119px;">T-048-56</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">nesfatin-1</td>
			<td>Phoenix Pharmaceuticals, Burlingame, CA, USA</td>
			<td style="width:119px;">T-003-26</td>
			<td>Radioactive</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">PYY3-36</td>
			<td>Phoenix Pharmaceuticals, Burlingame, CA, USA</td>
			<td style="width:119px;">T-059-02&#160;</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">somatostatin-28</td>
			<td>Phoenix Pharmaceuticals, Burlingame, CA, USA</td>
			<td style="width:119px;">T-060-16&#160;</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ZORBAX Rapid Resolution HT SB-C18 column</td>
			<td>Agilent Technologies, Santa Clara, CA, USA</td>
			<td style="width:119px;">822700-902</td>
			<td>2.1 x 50 mm, 1.8 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agilent 1200 LC&#160;</td>
			<td>Agilent Technologies, Santa Clara, CA, USA</td>
			<td style="width:119px;"></td>
			<td>HPLC, several components, therefore no single catalog number</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Kisspeptin&#160; RIA</td>
			<td>Phoenix Pharmaceuticals, Burlingame, CA, USA</td>
			<td># RK-048-56</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Total ghrelin RIA</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td># GHRT-89HK&#160;</td>
			<td>Radioactive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:343px;">Active ghrelin RIA</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td># GHRA-88HK</td>
			<td>Radioactive</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:343px;">SigmaStat 3.1</td>
			<td>Systat Software, San Jose, CA, USA</td>
			<td style="width:119px;">online download</td>
			<td></td>
		</tr>
	</tbody>
</table>

a rapid method for blood processing to increase the yield of plasma peptide levels in human blood

Research in the field of food intake regulation is gaining importance. This often includes the measurement of peptides regulating food intake. For the correct determination of a peptide&#39;s concentration, it should be stable during blood processing. However, this is not the case for several peptides which are quickly degraded by endogenous peptidases. Recently, we developed a blood processing method employing Reduced temperatures, Acidification, Protease inhibition, Isotopic exogenous controls and Dilution (RAPID) for the use in rats. Here, we have established this technique for the use in humans and investigated recovery, molecular form and circulating concentration of food intake regulatory hormones. The RAPID method significantly improved the recovery for 125I-labeled somatostatin-28 (+39%), glucagon-like peptide-1 (+35%), acyl ghrelin and glucagon (+32%), insulin and kisspeptin (+29%), nesfatin-1 (+28%), leptin (+21%) and peptide YY3-36 (+19%) compared to standard processing (EDTA blood on ice, p&#160;&#60;0.001). High performance liquid chromatography showed the elution of endogenous acyl ghrelin at the expected position after RAPID processing, while after standard processing 62% of acyl ghrelin were degraded resulting in an earlier peak likely representing desacyl ghrelin. After RAPID processing the acyl/desacyl ghrelin ratio in blood of normal weight subjects was 1:3 compared to 1:23 following standard processing (p&#160;= 0.03). Also endogenous kisspeptin levels were higher after RAPID compared to standard processing (+99%, p&#160;= 0.02). The RAPID blood processing method can be used in humans, yields higher peptide levels and allows for assessment of the correct molecular form.

RAPID blood processing increases the yield of 125I-radiolabeled peptides in human blood compared to standard blood processing. 
After standard blood processing (EDTA blood on ice), the recovery of radiolabeled peptides was ~60% in 9/9 peptides (ranging from 48-68%, Figure 1A-K). RAPID processing improved the yield in all 125I-labeled peptides, namely in somatostatin-28 (+39%, Figure 1A), glucagon-like peptide-1 ...

Watch this Scientific Journal Video about A RAPID Method for Blood Processing to Increase the Yield of Plasma Peptide Levels in Human Blood at JoVE.com

A RAPID Method for Blood Processing to Increase the Yield of Plasma Peptide Levels in Human Blood

The RAPID blood processing method can be used in humans and yields higher peptide levels as well as allows for assessment of the correct molecular form. Therefore, this method will be a valuable tool in peptide research.

Research in the field of food intake regulation is gaining importance. This often includes the measurement of peptides regulating food intake. For the ...

The overall goal of this RAPID method is to improve the yield of endogenous peptide hormones to be measured in human blood. The RAPID method was recently established for the use in rats, and is also suited for the use in human blood. The RAPID method improves the yield, and allows detection of the correct molecular form of endogenous peptide.The RAPID method is easy to use. However, the RAPID method is more time consuming and more expensive compared to standard blood sampling. So it might be more applicable in the research setting.Visual demonstration of this method is critical, as the timely dilution of the samples as well as the elution of great importance to ensure a proper peptide level. Collect venous blood at a standardized time after an overnight fast from a forearm vein. And process according to standard procedures, or the RAPID method.Instruct the subjects not to exercise or smoke before blood withdrawal. For standard processing, collect blood in chilled EDTA containing tubes and centrifuge within 10 minutes at 3000 Gs for 10 minutes at four degrees Celsius. Collect the supernatant, and keep it minus 80 degrees Celsius until further processing by radioimmunoassay.For RAPID processing, immediately dilute blood one to 10, in ice cold RAPID buffer. PH three point six, containing zero point one molar amoniumasitate. Zero point five molar sodium chloride, and enzyme inhibitors.Within 10 minutes, centrifuge the RAPID sample at 3000 Gs for 10 minutes at four degrees Celsius, and collect the supernatant, using a pipette. Next, charge chromatography cartridges with 100%actitonitrile, at 10 milliliters per minute. Following equilibration with 0.1%trifluoroacetic, or TFA.Load with the RAPID sample supernatant, at a constant rate of one milliliter per minute, using a syringe pump. After washing the cartridges with three milliliters of 0.1%TFA, at 10 milliliters per minute, slowly elute the RAPID sample with two milliliters of 70%acetonitrile containing 0.1%TFA, at two milliliters per minute. Dry the eluted samples using vacuum centrifugation, and store at minus 80 degrees Celsius, until further processing by radioimmunoassay.Obtain iodine 125 radio labeled human peptides. Keep the peptides in powder form until the experiment. Then freshly dilute in 0.1%acetic acid.For standard processing, directly after blood withdrawal, into chilled EDTA containing tubes, transfer one milliliter of blood in a tube with 50 microliters of radiolabel, containing 3000 to 6000 CPM. For RAPID processing, transfer one milliliter of EDTA containing blood into a tube holding nine milliliters of RAPID buffer, and 500 microliters of radiolabel contain 30, 000 to 60, 000 CPM. Due to the one to 10 dilution, use a 10 times higher volume of radiolabel for RAPID processing.Directly after applying the different steps of the RAPID method, assess the recovery of radioactively labeled peptides by using a gamma counter. Do not dry the samples by vacuum centrifugation, and do note store at minus 80 degrees Celsius. For measurement, transfer the supernatant to tubes fitting into the gamma counter.And assess the counts per minute. Measure the whole supernatant in standard samples. In RAPID samples, analyze one tenth of the total volume to achieve a comparable amount of radiolabel used.As a 100%standard, use two samples with 50 microliters of iodine 125 radiolabeled peptide that do not undergo processing. Measure the radioactivity of all of the samples at the same time. Withdraw blood, in chilled EDTA containing tubes, and transfer one milliliter to tubes holding 200 microliters of radiolabeled acyl ghrelin, containing 15, 000 to 20, 000 CPM, for standard processing.For RAPID processing, transfer one milliliter of blood into a tube holding nine milliliters of rapid buffer, and 200 microliters of radiolabeled acyl ghrelin containing 15, 000 to 20, 000 CPM. Afterwards, process samples as before. For further analysis by reversed phase HPLC, directly load the samples onto a stable bond C18 column equilibrated in 17%acetonitrile in water supplemented with 0.1%TFA.After five minutes of equilibration, use a gradient from 17 to 40%acetonitrile, to elute the sample in 40 minutes, at one milliliter per minute. Collect fractions of one milliliter every minute, and analyze radioactivity using a gamma counter. In a separate experiment, load 200 microliters of radiolabeled acyl ghrelin containing 15, 000 to 20, 000 CPM onto the column directly and perform HPLC as before.For radioimmunoassay, thaw frozen supernatants and vacuum dried powder at room temperature. Immediately before radioimmunoassay, re suspend dry RAPID samples in double distilled water, according to the original volume of plasma. Assess kisspeptin and total ghrelin as well as acyl ghrelin, using commercial radioimunoassays according to the manufacturer's protocols.Use borosilicate tubes that allow stable palette formation. On day one, incubate the samples with assay buffer, and primary atibody, in the dilution provided by the manufacturer for a period of 24 hours. On day two, add the iodine 125 tracer, vortex, and incubate for a period of 24 hours.On day three, add the percipitating reagent, vortex, and incubate as recommended by the manufacturer. Then, centrifuge the tubes at 3, 000 Gs for 20 minutes at four degrees Celsius. Remove the supernatants and count the radioactivity in the palettes, using a gamma counter.Calculate the desacyl ghrelin, as the difference of the total ghrelin minus acyl ghrelin. Asses the acyl, desacyl ghrelin ratio, by diving acyl by desacyl ghrelin for each individual sample. If possible, process all samples in one batch, to avoid inter assay variability.RAPID blood processing increases the yield of iodine 125 radiolabeled peptides in human blood, as compared to standard blood processing. After standard blood processing, the recovery of radiolabeled peptides ranged from 48%to 68%in nine peptides. RAPID processing improved the yield in all iodine 125 labeled peptides, with a recovery ranging from 71%to 98%Shown here is the elution profile of iodine 125 labeled acyl ghrelin in human blood following standard or RAPID blood processing.After RAPID processing, iodine 125 labeled ghrelin eluded at the expected position. While after the standard procedure, an earlier peak was observed. Likely corresponding to desacyl ghrelin.This represented a 62%degradation of the peptide. RAPID blood processing improves the acyl, desacyl ghrelin ratio as compared to standard processing. After RAPID processing, the acyl, desacyl ghrelin ratio in blood of normal weight subjects was one to three.As compared to one to 23 following standard blood processing. Similar results were observed under anorexic and obese conditions. RAPID blood processing results in increased endogenous kisspeptin blood levels as compared to standard processing.In both anorexic and normal weight subjects, circulating endogenous kisspeptin levels were significantly higher following RAPID as compared to standard processing. The difference did not reach significance under conditions of obesity. Once mastered, and performed properly, this technique can be done in less than one hour.This method is especially important when the expected concentration of the peptide is low, or the differences between the groups are small. A general recommendation for peptides cannot be given. The potential benefit for each peptide should be tested once at the beginning.This technique paves the way for researchers in different fields to explore the yield and more importantly, the correct molecular form of endogenous peptide hormones. After watching this video, you should have a good understanding of how to apply RAPID method for blood processing in humans.

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Research

JoVE Journal

Immunology and Infection

Depletion of Specific Cell Populations by Complement Depletion

The purification of immune cell populations is often required in order to study their unique functions. In particular, molecular approaches such as real-time PCR and microarray analysis require the isolation of cell populations with high purity. Commonly used purification strategies include fluorescent activated cell sorting (FACS), magnetic bead separation and complement depletion. Of the three strategies, complement depletion offers the advantages of being fast, inexpensive, gentle on the cells and a high cell yield. The complement system is composed of a large number of plasma proteins that when activated initiate a proteolytic cascade culminating in the formation of a membrane-attack complex that forms a pore on a cell surface resulting in cell death1. The classical pathway is activated by IgM and IgG antibodies and was first described as a mechanism for killing bacteria. With the generation of monoclonal antibodies (mAb), the complement cascade can be used to lyse any cell population in an antigen-specific manner. Depletion of cells by the complement cascade is achieved by the addition of complement fixing antigen-specific antibodies and rabbit complement to the starting cell population. The cells are incubated for one hour at 37&deg;C and the lysed cells are subsequently removed by two rounds of washing. MAb with a high efficiency for complement fixation typically deplete 95-100% of the targeted cell population. Depending on the purification strategy for the targeted cell population, complement depletion can be used for cell purification or for the enrichment of cell populations that then can be further purified by a subsequent method.

To effectively study the function of immune cell populations their purification is often required. Complement depletion is a fast and inexpensive technique for the isolation of immune cell populations with high purity.

The purification of immune cell populations is often required in order to study their unique functions.  In particular, molecular approaches such as ...

Isolation of Mouse Peritoneal Cavity Cells

The peritoneal cavity is a membrane-bound and fluid-filled abdominal cavity of mammals, which contains the liver, spleen, most of the gastro-intestinal tract and other viscera. It harbors a number of immune cells including macrophages, B cells and T cells. The presence of a high number of na&iuml;ve macrophages in the peritoneal cavity makes it a preferred site for the collection of na&iuml;ve tissue resident macrophages (1). The peritoneal cavity is also important to the study of B cells because of the presence of a unique peritoneal cavity-resident B cell subset known as B1 cells in addition to conventional B2 cells. B1 cells are subdivided into B1a and B1b cells, which can be distinguished by the surface expression of CD11b and CD5. B1 cells are an important source of natural IgM providing early protection from a variety of pathogens (2-4). These cells are autoreactive in nature (5), but how they are controlled to prevent autoimmunity is still not understood completely. On the contrary, CD5+ B1a cells possess some regulatory properties by virtue of their IL-10 producing capacity (6). Therefore, peritoneal cavity B1 cells are an interesting cell population to study because of their diverse function and many unaddressed questions associated with their development and regulation. The isolation of peritoneal cavity resident immune cells is tricky because of the lack of a defined structure inside the peritoneal cavity. Our protocol will describe a procedure for obtaining viable immune cells from the peritoneal cavity of mice, which then can be used for phenotypic analysis by flow cytometry and for different biochemical and immunological assays.

The peritoneal cavity in mammals contains different immune cell populations crucial for innate immune responses. An efficient isolation method is required for biochemical and functional analyses of these cells. Here we provide a comprehensive method for the isolation of peritoneal cavity cells in the mouse.

The peritoneal cavity is a membrane-bound and fluid-filled abdominal cavity of mammals, which contains the liver, spleen, most of the gastro-intestinal ...

Purification of Specific Cell Population by Fluorescence Activated Cell Sorting (FACS)

Experimental and clinical studies often require highly purified cell populations.  FACS is a technique of choice to purify cell populations of known phenotype.  Other bulk methods of purification include panning, complement depletion and magnetic bead separation.  However, FACS has several advantages over other available methods.  FACS is the preferred method when very high purity of the desired population is required, when the target cell population expresses a very low level of the identifying marker or when cell populations require separation based on differential marker density.  In addition, FACS is the only available purification technique to isolate cells based on internal staining or intracellular protein expression, such as a genetically modified fluorescent protein marker.  FACS allows the purification of individual cells based on size, granularity and fluorescence.  In order to purify cells of interest, they are first stained with fluorescently-tagged monoclonal antibodies (mAb), which recognize specific surface markers on the desired cell population (1).  Negative selection of unstained cells is also possible.  FACS purification requires a flow cytometer with sorting capacity and the appropriate software.  For FACS, cells in suspension are passed as a stream in droplets with each containing a single cell in front of a laser.  The fluorescence detection system detects cells of interest based on predetermined fluorescent parameters of the cells.  The instrument applies a charge to the droplet containing a cell of interest and an electrostatic deflection system facilitates collection of the charged droplets into appropriate collection tubes (2).  The success of staining and thereby sorting depends largely on the selection of the identifying markers and the choice of mAb.  Sorting parameters can be adjusted depending on the requirement of purity and yield.  Although FACS requires specialized equipment and personnel training, it is the method of choice for isolation of highly purified cell populations.

Purification of Specific Cell Population by Fluorescence Activated Cell Sorting FACS

For many scientific studies requiring a biological and chemical analysis of cell populations the cells must be in a high state of purity. Fluorescence activated cell sorting (FACS) is a superior method in which to obtain pure cell populations.

Experimental and clinical studies often require highly purified cell populations.  FACS is a technique of choice to purify cell populations of known ...

Introducing Shear Stress in the Study of Bacterial Adhesion

During bacterial infections a sequence of interactions occur between the pathogen and its host. Bacterial adhesion to the host cell surface is often the initial and determining step of the pathogenesis. Although experimentally adhesion is mostly studied in static conditions adhesion actually takes place in the presence of flowing liquid. First encounters between bacteria and their host often occur at the mucosal level, mouth, lung, gut, eye, etc. where mucus flows along the surface of epithelial cells. Later in infection, pathogens occasionally access the blood circulation causing life-threatening illnesses such as septicemia, sepsis and meningitis. A defining feature of these infections is the ability of these pathogens to interact with endothelial cells in presence of circulating blood. The presence of flowing liquid, mucus or blood for instance, determines adhesion because it generates a mechanical force on the pathogen. To characterize the effect of flowing liquid one usually refers to the notion of shear stress, which is the tangential force exerted per unit area by a fluid moving near a stationary wall, expressed in dynes/cm2. Intensities of shear stress vary widely according to the different vessels type, size, organ, location etc. (0-100 dynes/cm2). Circulation in capillaries can reach very low shear stress values and even temporarily stop during periods ranging between a few seconds to several minutes 1. On the other end of the spectrum shear stress in arterioles can reach 100 dynes/cm2 2. The impact of shear stress on different biological processes has been clearly demonstrated as for instance during the interaction of leukocytes with the endothelium 3. To take into account this mechanical parameter in the process of bacterial adhesion we took advantage of an experimental procedure based on the use of a disposable flow chamber 4. Host cells are grown in the flow chamber and fluorescent bacteria are introduced in the flow controlled by a syringe pump. We initially focused our investigations on the bacterial pathogen Neisseria meningitidis, a Gram-negative bacterium responsible for septicemia and meningitis. The procedure described here allowed us to study the impact of shear stress on the ability of the bacteria to: adhere to cells 1, to proliferate on the cell surface 5and to detach to colonize new sites 6 (Figure 1). Complementary technical information can be found in reference 7. Shear stress values presented here were chosen based on our previous experience1 and to represent values found in the literature. The protocol should be applicable to a wide range of pathogens with specific adjustments depending on the objectives of the study.

During the infection process, a key step is the adhesion of pathogens with host cells. In most instances this adhesion step occurs in the presence of mechanical stress generated by flowing liquid. We describe a technique that introduces shear stress as an important parameter in the study of bacterial adhesion.

During bacterial infections a sequence of interactions occur between the pathogen and its host. Bacterial adhesion to the host cell surface is often the ...

High-throughput Detection Method for Influenza Virus

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, precise diagnosis of the infecting strain and rapid high-throughput screening of vast numbers of clinical samples is paramount to control the spread of pandemic infections. Current clinical diagnoses of influenza infections are based on serologic testing, polymerase chain reaction, direct specimen immunofluorescence and cell culture 1,2.
Here, we report the development of a novel diagnostic technique used to detect live influenza viruses. We used the mouse-adapted human A/PR/8/34 (PR8, H1N1) virus 3 to test the efficacy of this technique using MDCK cells 4. MDCK cells (104 or 5 x 103 per well) were cultured in 96- or 384-well plates, infected with PR8 and viral proteins were detected using anti-M2 followed by an IR dye-conjugated secondary antibody. M2 5 and hemagglutinin 1 are two major marker proteins used in many different diagnostic assays. Employing IR-dye-conjugated secondary antibodies minimized the autofluorescence associated with other fluorescent dyes. The use of anti-M2 antibody allowed us to use the antigen-specific fluorescence intensity as a direct metric of viral quantity. To enumerate the fluorescence intensity, we used the LI-COR Odyssey-based IR scanner. This system uses two channel laser-based IR detections to identify fluorophores and differentiate them from background noise. The first channel excites at 680 nm and emits at 700 nm to help quantify the background. The second channel detects fluorophores that excite at 780 nm and emit at 800 nm. Scanning of PR8-infected MDCK cells in the IR scanner indicated a viral titer-dependent bright fluorescence. A positive correlation of fluorescence intensity to virus titer starting from 102-105 PFU could be consistently observed. Minimal but detectable positivity consistently seen with 102-103 PFU PR8 viral titers demonstrated the high sensitivity of the near-IR dyes. The signal-to-noise ratio was determined by comparing the mock-infected or isotype antibody-treated MDCK cells.
Using the fluorescence intensities from 96- or 384-well plate formats, we constructed standard titration curves. In these calculations, the first variable is the viral titer while the second variable is the fluorescence intensity. Therefore, we used the exponential distribution to generate a curve-fit to determine the polynomial relationship between the viral titers and fluorescence intensities. Collectively, we conclude that IR dye-based protein detection system can help diagnose infecting viral strains and precisely enumerate the titer of the infecting pathogens.

This method describes the use of Infrared dye based imaging system for detection of H1N1 in bronchioalveolar lavage (BAL) fluid of infected mice at a high sensitivity. This methodology can be performed in a 96- or 384-well plate, requires &lt;10 &mu;l volume of test material and has the potential for concurrent screening of multiple pathogens.

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, ...

Antigens Protected Functional Red Blood Cells By The Membrane Grafting Of Compact Hyperbranched Polyglycerols

Red blood cell (RBC) transfusion is vital for the treatment of a number of acute and chronic medical problems such as thalassemia major and sickle cell anemia 1-3. Due to the presence of multitude of antigens on the RBC surface (~308 known antigens 4), patients in the chronic blood transfusion therapy develop alloantibodies due to the miss match of minor antigens on transfused RBCs 4, 5. Grafting of hydrophilic polymers such as polyethylene glycol (PEG) and hyperbranched polyglycerol (HPG) forms an exclusion layer on RBC membrane that prevents the interaction of antibodies with surface antigens without affecting the passage of small molecules such as oxygen ,glucose, and ions3. At present no method is available for the generation of universal red blood donor cells in part because of the daunting challenge presented by the presence of large number of antigens (protein and carbohydrate based) on the RBC surface and the development of such methods will significantly improve transfusion safety, and dramatically improve the availability and use of RBCs. In this report, the experiments that are used to develop antigen protected functional RBCs by the membrane grafting of HPG and their characterization are presented. HPGs are highly biocompatible compact polymers 6, 7, and are expected to be located within the cell glycocalyx that surrounds the lipid membrane 8, 9 and mask RBC surface antigens10, 11.

The cell membrane modification of red blood cells (RBCs) with hyperbranched polyglycerol (HPG) is presented. Modified RBCs were characterized by aqueous two phase partitioning, osmotic fragility and complement mediated lysis. The camouflage of surface proteins and antigens was evaluated using the flow cytometry and Micro Typing System (MTS) blood phenotyping cards.

Red blood cell (RBC) transfusion is vital for the treatment of a number of acute and chronic medical problems such as thalassemia major and sickle cell ...

Rapid Identification of Gram Negative Bacteria from Blood Culture Broth Using MALDI-TOF Mass Spectrometry

An important role of the clinical microbiology laboratory is to provide rapid identification of bacteria causing bloodstream infection. Traditional identification requires the sub-culture of signaled blood culture broth with identification available only after colonies on solid agar have matured. MALDI-TOF MS is a reliable, rapid method for identification of the majority of clinically relevant bacteria when applied to colonies on solid media. The application of MALDI-TOF MS directly to blood culture broth is an attractive approach as it has potential to accelerate species identification of bacteria and improve clinical management. However, an important problem to overcome is the pre-analysis removal of interfering resins, proteins and hemoglobin&#160;contained in blood culture specimens which, if not removed, interfere with the MS spectra and can result in insufficient or low discrimination identification scores. In addition it is necessary to concentrate bacteria to develop spectra of sufficient quality. The presented method describes the concentration, purification, and extraction of Gram negative bacteria allowing for the early identification of bacteria from a signaled blood culture broth.

The application of matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) directly to blood culture broth expedites the identification of bacteria. The presented method is a rapid and reliable method for identification of Gram negative bacteria directly from blood culture broth.

An important role of the clinical microbiology laboratory is to provide rapid identification of bacteria causing bloodstream infection. Traditional ...

A Semi-automated Approach to Preparing Antibody Cocktails for Immunophenotypic Analysis of Human Peripheral Blood

Immunophenotyping of peripheral blood by flow cytometry determines changes in the frequency and activation status of peripheral leukocytes during disease and treatment. It has the potential to predict therapeutic efficacy and identify novel therapeutic targets. Whole blood staining utilizes unmanipulated blood, which minimizes artifacts that can occur during sample preparation. However, whole blood staining must also be done on freshly collected blood to ensure the integrity of the sample. Additionally, it is best to prepare antibody cocktails on the same day to avoid potential instability of tandem-dyes and prevent reagent interaction between brilliant violet dyes. Therefore, whole blood staining requires careful standardization to control for intra and inter-experimental variability.
Here, we report deployment of an automated liquid handler equipped with a two-dimensional (2D) barcode reader into a standard process of making antibody cocktails for flow cytometry. Antibodies were transferred into 2D barcoded tubes arranged in a 96 well format and their contents compiled in a database. The liquid handler could then locate the source antibody vials by referencing antibody names within the database. Our method eliminated tedious coordination for positioning of source antibody tubes. It provided versatility allowing the user to easily change any number of details in the antibody dispensing process such as specific antibody to use, volume, and destination by modifying the database without rewriting the scripting in the software method for each assay.
A proof of concept experiment achieved outstanding inter and intra- assay precision, demonstrated by replicate preparation of an 11-color, 17-antibody flow cytometry assay. These methodologies increased overall throughput for flow cytometry assays and facilitated daily preparation of the complex antibody cocktails required for the detailed phenotypic characterization of freshly collected anticoagulated peripheral blood.

Whole blood Immunophenotyping is indispensable for monitoring the human immune system. However, the number of reagents required and the instability of specific fluorochromes in premixed cocktails necessitates daily reagent preparation. Here we show that semi-automated preparation of staining antibody cocktail helps establish reliable immunophenotyping by minimizing variability in reagent dispensing.

Immunophenotyping of peripheral blood by flow cytometry determines changes in the frequency and activation status of peripheral leukocytes during disease ...

Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation of experiments, fresh or frozen monocytes are cultured in flasks for 1 week with M-CSF to induce their differentiation into macrophages. Then, the macrophages can be harvested and seeded into culture wells at required cell densities for carrying out experiments. The use of defined numbers of macrophages rather than defined numbers of monocytes to initiate macrophage cultures for experiments yields macrophage cultures in which the desired cell density can be more consistently attained. Use of cryopreserved monocytes reduces dependency on donor availability and produces more homogeneous macrophage cultures.

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. The protocol utilizes cryopreservation of monocytes coupled with their bulk differentiation into macrophages. Then harvested macrophages can then be seeded into culture wells at required cell densities for carrying out experiments.

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation ...

A Simple Flow Cytometric Method to Measure Glucose Uptake and Glucose Transporter Expression for Monocyte Subpopulations in Whole Blood

Monocytes are innate immune cells that can be activated by pathogens and inflammation associated with certain chronic inflammatory diseases. Activation of monocytes induces effector functions and a concomitant shift from oxidative to glycolytic metabolism that is accompanied by increased glucose transporter expression. This increased glycolytic metabolism is also observed for trained immunity of monocytes, a form of innate immunological memory. Although in vitro protocols examining glucose transporter expression and glucose uptake by monocytes have been described, none have been examined by multi-parametric flow cytometry in whole blood. We describe a multi-parametric flow cytometric protocol for the measurement of fluorescent glucose analog 2-NBDG uptake in whole blood by total monocytes and the classical (CD14++CD16-), intermediate (CD14++CD16+) and non-classical (CD14+CD16++) monocyte subpopulations. This method can be used to examine glucose transporter expression and glucose uptake for total monocytes and monocyte subpopulations during homeostasis and inflammatory disease, and can be easily modified to examine glucose uptake for other leukocytes and leukocyte subpopulations within blood.

Monocytes are integral components of the human innate immune system that rely on glycolytic metabolism when activated. We describe a flow cytometry protocol to measure glucose transporter expression and glucose uptake by total monocytes and monocyte subpopulations in fresh whole blood.

Monocytes are innate immune cells that can be activated by pathogens and inflammation associated with certain chronic inflammatory diseases. Activation of ...