We would like to acknowledge Professor Roger Hainsworth, who developed this technique. We are grateful to Mr. King Hang Chao and Mr. Wang-Joe Woo for their assistance with photography.
This work is supported by Simon Fraser University and the Heart and Stroke Foundation of Canada.

Throughout testing, continuous beat-to-beat blood pressure and electrocardiogram (ECG) monitoring is paramount. This ensures subject safety, and prompt termination of the test with the onset of presyncope. Beat-to-beat blood pressure recordings can be obtained through arterial catheterization, or finger plethysmography31-33. The latter is used in this protocol because it is non-invasive and can assess the onset of presyncope with the same accuracy as catherization31,34, without the detrimental impact of invasive monitoring on OT1. Using the Modelflow technique changes in stroke volume, cardiac output, and total peripheral resistance can be derived from the finger arterial pressure waveform35,36. Additional noninvasive measures that may aid the haemodynamic evaluation can also be conducted, and will be described here. Continuous end tidal oxygen (PETO2) and carbon dioxide (PETCO2) monitoring using a nasal cannula allows the evaluation of any contribution of hyperventilation to the subject's symptoms. Finally, monitoring both brachial and cerebral blood flow velocities using Doppler ultrasound can be undertaken to allow the determination of peripheral and cerebral vascular responses to orthostasis. In addition, measurements of venous pooling and capillary filtration could also be obtained using impedance plethysmography20. Ultimately, this protocol allows assessment of postural cardiovascular reflex control in a controlled and reproducible setting.
1. Equipment
<ol>
 <li>The manually adjustable tilt table is capable of moving from -15 to 60 &deg; in 10 &deg; increments (Figure 1). It includes an adjustable right-arm rest with an adjustable holder for a brachial ultrasound probe (Figure 1D), an adjustable footplate for the subject to stand on, and a seat belt to secure the subject's legs (Figure 1E).</li>
 <li>An LBNP chamber with an attached pressure gauge fits in a wooden groove filled with neoprene onto the bottom half of the tilt table and is secured in place by four adjustable straps (Figure 1). A clear Plexiglas material can be employed for the chamber if desired, to enable visualization of the subjects' legs, and thus visual monitoring of any skeletal muscle pumping activity.</li>
 <li>A wooden waist board is attached to the top of the chamber with a neoprene surround at the level of the subject's iliac crest to provide an air-tight seal with the chamber (Figure 1B). The level of the iliac crest is chosen because it avoids the application of LBNP to the abdomen, which can be uncomfortable, but ensures a standardized stimulus for individuals of different statures.</li>
 <li>Perform continuous beat-to-beat data acquisition with a sampling frequency of 1 KHz using an analog-to-digital converter. Visualize all data simultaneously in real time throughout testing using LabChart (Powerlab 16/30, AD Instruments, Colorado Springs, CO).</li>
 <li>Conduct testing in a temperature-controlled room (20-22 &deg;C) to avoid the known effect of heat stress upon OT37. Tests are ideally conducted in the mornings because of the effect of diurnal rhythms on baroreflex control38. In some cases, a familiarization session is advised to minimize the influence of a "stress response" on the procedure.</li>
 <li>Instruct subjects to have only a light breakfast, to minimize possible confounders due to post-prandial hypotension, and to avoid caffeine and strenuous exercise on the morning of testing. Subjects should fast for 2 hr prior to testing. They should also abstain from drinking alcohol for 24 hr prior to testing, to eliminate the diuretic effect of alcohol and consequent reductions in plasma volume, which are known to reduce OT39.</li>
 <li>Figure 2 outlines the protocol. Stand the subject on the table foot plate and move them into a supine position (Figure 1). Once supine, align the iliac crest with the center of the table. This allows for ease of tilting, and ensures standardized positioning of the LBNP chamber. Adjust the footplate accordingly. A foot plate support is preferred because tables with saddle supports are associated with increased false positive responses, probably due to excess compression of leg and pelvic veins6.</li>
 <li>Loosley position a strap just above the knee to promote passive standing and provide postural support. Instruct subjects not to move their legs during testing. Position the subject's right arm on the arm rest, adjusted so that it is comfortably supported at heart level. Attach monitoring equipment.</li>
 <li>Conduct beat-to-beat blood pressure monitoring using the Finometer, according to the manufacturer's instructions40. Chose the finger cuff that fits appropriately onto the middle phalanx of the subject's right middle finger. Use a brachial cuff to internally calibrate the Finometer prior to data collection. Enter the subject's sex, age, height and weight into the Finometer to enable appropriate assumptions for the Modelflow algorithms35,36.</li>
 <li>Continuous ECG monitoring is important for the accurate determination of heart rate responses, and prompt identification of any cardiac arrhythmia, should they occur. Apply ECG electrodes in a modified lead II configuration, ensuring that the electrode sites do not interfere with positioning of the neoprene waist board.</li>
 <li>Determine peripheral vascular responses using Doppler ultrasound of the brachial artery of the right arm supported at heart level (to avoid the influence of hydrostatic pressure changes on blood pressure and velocity in the arm). Palpate the artery until the pulse is located. Apply ultrasound gel to this area and position an 8 MHz ultrasound probe so that a brachial artery velocity waveform is obtained (Figures 3A,B).</li>
 <li>Once the signal is identified, optimize the depth and gain, and tighten the adjustable holder to keep the angle of insonation constant for the duration of the test (Figure 3B). This is important because, according to the Doppler shift equation, changes in velocity will be proportional to changes in flow if the angle of insonation and arterial diameter are constant19,21.</li>
 <li>Determine cerebral vascular responses similarly (Figures 4A,B). Secure the cerebral ultrasound probe (2 MHz) in place using a plastic headset or fabric headbands (Figure 4B) to ensure faithful signal detection and a constant angle of insonation throughout testing.</li>
 <li>Determine blood velocity continuously from the middle cerebral artery. This vessel is chosen because of its convenience of identification, large contribution to global cerebral perfusion, and constant diameter during orthostatic stress41, ensuring changes in velocity are proportional to changes in flow. Apply ultrasound gel to the subject's temple and locate the vessel (Figure 4A). Once identified, optimize the depth and gain settings.</li>
 <li>Attach the nasal cannula. Nasal sampling is preferred because it permits the subject to talk freely during testing (unlike with use of a mouthpiece). This is important to enable self-report and recognition of symptoms, while avoiding invasive blood sampling that may adversely impact OT. However, during speech, or when the subject is breathing through their mouth, accuracy of these readings may be affected. Encourage subjects to breathe through their nose.</li>
 <li>Place the LBNP chamber on the table and secure with the straps. Select a waist board that fits snugly so that an airtight seal with the neoprene can be achieved (Figure 1B). The wooden component of the waist board should not be touching the subject. Secure the waist board to the chamber. Connect the chamber to a negative pressure source, via a variable resistor (Figure 1C).</li>
</ol>
2. Data Collection
<ol>
 <li>Record data for 20 min in the supine position. Shorter rest periods are associated with greater falls in blood pressure when upright, presumably because the reabsorption of any fluid that has collected in the dependent limbs prior to lying down is not yet complete20.</li>
 <li>At the end of the supine phase maneuver the table to a tilt angle of 60 &deg;. This angle is preferred because it affords nearly 90% of the maximal vertical displacement, while allowing the subject to remain relaxed and supported against the tilt table (minimizing the confounding effect of skeletal muscle pumping activity with higher tilt angles). Less steep angles may increase the false negative rate; although the physiological effects of tilting are similar for angles &ge;60 &deg;, higher tilt angles are associated with a reduction in specificity6.</li>
 <li>Complete the transition to upright within thirty seconds. The transition time is not known to affect OT and it is more pleasant for the subject if tilting is not excessively rapid. However, very slow tilt maneuvers may be associated with lower activation of muscle sympathetic nerve activity and should be avoided42.</li>
 <li>Continuously monitor the subject's cardiovascular parameters as well as their subjective experience. The test should be stopped immediately, and the subject returned to a supine position, if any of the following end-point criteria are met: blood pressure is 80 mmHg or below; heart rate is lower than 50 beats per minute (bpm) or higher than 170 bpm; and the subject experiences symptoms such as dizziness, warmth, and requests to stop; or the protocol is completed.</li>
 <li>Unless there is a specific desire to initiate syncope, terminate the test rapidly at the onset of presyncopal signs and symptoms, avoiding frank syncope.</li>
 <li>After 20 min of tilting apply LBNP, while still tilted, at -20 mmHg for a further 10 min. It is important to inform the subject of the impending onset of LBNP to prevent a startle response to the sensation and sound of the LBNP.</li>
 <li>After 10 min, increase the LBNP to -40 mmHg for another 10 min.</li>
 <li>After 10 min, increase the LBNP to -60 mmHg and continue for another 10 min. At the end of this phase, turn off the LBNP and return the subject to the supine position.</li>
 <li>It is theoretically possible to increase the vacuum source to achieve -80 mmHg LBNP if a presyncopal end-point is not reached at the end of this phase. However, in practice this high level of LBNP is uncomfortable for the subject, and presyncope usually occurs at much lower levels of orthostatic stress, even in healthy controls. The largest OT we have recorded was 50 min (the end of -60 mmHg) and this was in a Peruvian high altitude resident with Chronic Mountain Sickness and an extremely high blood volume43.</li>
 <li>OT is defined as the time to presyncope in minutes from the onset of the head-up tilting phase.</li>
 <li>To ensure the rapid termination of symptoms and signs of presyncope, and so to minimize the likelihood of syncope or asystole, a rapid return to supine is desired (ideally ~1 sec). For this reason, a manual tilt table may be preferred to an autonomic one, which may not have the capability for such rapid transitions. Returning the table to a slightly head-down position (-15 &deg;) may promote faster resolution of the presyncopal event. Once all variables have returned to the supine levels and any symptoms are resolved, remove the monitoring equipment.</li>
 <li>After removing the LBNP chamber, remove the strap over the subject's legs and lower the footplate to its original position. Ensure the subject is positioned with their feet on the plate.</li>
 <li>Before returning the table to an upright position, instruct the subject to tense their leg muscles throughout the transition to avoid any symptoms from reoccurring as the table is tilted to facilitate them getting off44,45. Ask the subject to sit after stepping off the table to ensure they are symptom-free before leaving the laboratory.</li>
</ol>

No conflicts of interest declared.

This technique is highly reproducible, has the ability to discriminate normal and abnormal responses with high sensitivity and specificity, and can provoke presyncope in all subjects, allowing for symptom recognition in patients with recurrent syncope. In a clinical setting, different types of syncope can be distinguished, allowing tailored treatment and management approaches. The impact of interventions can readily be assessed. With additional cardiovascular monitoring, reflex responses can also be evaluated.
<p cl...

<table border="1">
 <tbody>
 <tr>
 <td>Equipment</td>
 <td>Manufacturer</td>
 <td>Location</td>
 </tr>
 <tr>
 <td>Tilt Table</td>
 <td>Custom-build</td>
 <td>Leeds, United Kingdom</td>
 </tr>
 <tr>
 <td>Finometer</td>
 <td>Finapres Medical Systems</td>
 <td>Amsterdam, The Netherlands</td>
 </tr>
 <tr>
 <td>Doppler Box</td>
 <td>Compumedics</td>
 <td>Singen, Germany</td>
 </tr>
 <tr>
 <td>Doppler software</td>
 <td>The DWL Doppler Company</td>
 <td>Singen, Germany</td>
 </tr>
 <tr>
 <td>Aquasonic Ultrasound gel</td>
 <td>Parker Laboratories, Inc.</td>
 <td>Fairfield, USA</td>
 </tr>
 <tr>
 <td>Headbands</td>
 <td>Lululemon</td>
 <td>Burnaby, Canada</td>
 </tr>
 <tr>
 <td>Headset</td>
 <td>Canadian Tire</td>
 <td>Burnaby, Canada</td>
 </tr>
 <tr>
 <td>ECG</td>
 <td>Finapres ECG Module, Finapres Medical Systems</td>
 <td>Amsterdam, The Netherlands</td>
 </tr>
 <tr>
 <td>Electrodes</td>
 <td>Red Dot</td>
 <td>Ontario, Canada</td>
 </tr>
 <tr>
 <td>Antiseptic Isopropyl Alcohol Pads</td>
 <td>Lernapharm</td>
 <td>Quebec, Canada</td>
 </tr>
 <tr>
 <td>O2Cap-Oxygen Analyser</td>
 <td>Oxigraph Inc.</td>
 <td>California, USA</td>
 </tr>
 <tr>
 <td>Airlife Nasal Oxygen Cannula</td>
 <td>Cardinal Health</td>
 <td>Mountainview, USA</td>
 </tr>
 <tr>
 <td>Powerlab 16/30</td>
 <td>AD Instruments</td>
 <td>Colorado Springs, USA</td>
 </tr>
 </tbody>
</table>

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.

Using this protocol, all subjects experience presyncope, and the definition of normal or abnormal responses is made largely based upon the time it takes to induce this reaction. OT is defined as the time to presyncope in minutes from the onset of upright tilting. Typical values for OT in healthy volunteers according to age and gender can be seen in Table 1. Patients with orthostatic intolerance exhibit presyncope earlier in the test, with 85% ending the test within the -20 mmHg phase compared to 23% of c...

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

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 ...

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20.6K Views.  Simon Fraser University. 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.

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

Manual Muscle Testing:  A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, and persistent nerve and muscle impairments after hospital discharge.1-6 Using an explicit protocol with a structured approach to training and quality assurance of research staff, manual muscle testing (MMT) is a highly reliable method for assessing strength, using a standardized clinical examination, for patients following ARDS, and can be completed with mechanically ventilated patients who can tolerate sitting upright in bed and are able to follow two-step commands. 7, 8 
This video demonstrates a protocol for MMT, which has been taught to &ge;43 research staff who have performed &gt;800 assessments on &gt;280 ARDS survivors. Modifications for the bedridden patient are included. Each muscle is tested with specific techniques for positioning, stabilization, resistance, and palpation for each score of the 6-point ordinal Medical Research Council scale.7,9-11 Three upper and three lower extremity muscles are graded in this protocol: shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion. These muscles were chosen based on the standard approach for evaluating patients for ICU-acquired weakness used in prior publications. 1,2.

Survivors of acute respiratory distress syndrome (ARDS) and critical illness frequently develop long-lasting muscle weakness. Manual muscle testing (MMT) is a standardized clinical examination commonly used to measure strength of peripheral skeletal muscle groups. This video demonstrates MMT using the 6-point Medical Research Council scale.

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, ...

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily life, despite similar visual deficits. We assume this could be due to variable development of compensatory strategies such as altered visual scanning behavior. Scanning compensatory therapy (SCT) is studied as part of the visual training after infarction next to vision restoration therapy. SCT consists of learning to make larger eye movements into the blind field enlarging the visual field of search, which has been proven to be the most useful strategy1, not only in natural search tasks but also in mastering daily life activities2. Nevertheless, in clinical routine it is difficult to identify individual levels and training effects of compensatory behavior, since it requires measurement of eye movements in a head unrestrained condition. Studies demonstrated that unrestrained head movements alter the visual exploratory behavior compared to a head-restrained laboratory condition3. Martin et al.4 and Hayhoe et al.5 showed that behavior demonstrated in a laboratory setting cannot be assigned easily to a natural condition. Hence, our goal was to develop a study set-up which uncovers different compensatory oculomotor strategies quickly in a realistic testing situation: Patients are tested in the clinical environment in a driving simulator. SILAB software (Wuerzburg Institute for Traffic Sciences GmbH (WIVW)) was used to program driving scenarios of varying complexity and recording the driver's performance. The software was combined with a head mounted infrared video pupil tracker, recording head- and eye-movements (EyeSeeCam, University of Munich Hospital, Clinical Neurosciences).
The positioning of the patient in the driving simulator and the positioning, adjustment and calibration of the camera is demonstrated. Typical performances of a patient with and without compensatory strategy and a healthy control are illustrated in this pilot study. Different oculomotor behaviors (frequency and amplitude of eye- and head-movements) are evaluated very quickly during the drive itself by dynamic overlay pictures indicating where the subjects gaze is located on the screen, and by analyzing the data. Compensatory gaze behavior in a patient leads to a driving performance comparable to a healthy control, while the performance of a patient without compensatory behavior is significantly worse. The data of eye- and head-movement-behavior as well as driving performance are discussed with respect to different oculomotor strategies and in a broader context with respect to possible training effects throughout the testing session and implications on rehabilitation potential.

Patients with visual deficits after stroke report about different constraints in daily life most likely due to variable compensatory strategies, which are difficult to differentiate in clinical routine. We present a clinical set-up which allows measurement of different compensatory head- and eye-movement-strategies and evaluating their effects on driving performance.

Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily ...

Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy

Physicians considering stereotactic ablative body radiation therapy (SBRT) for the treatment of extracranial cancer targets must be aware of the sizeable risks for normal tissue injury and the hazards of physical tumor miss. A first-of-its-kind SBRT platform achieves high-precision ablative radiation treatment through a combination of versatile real-time imaging solutions and sophisticated tumor tracking capabilities. It uses dual-diagnostic kV x-ray units for stereoscopic open-loop feedback of cancer target intrafraction movement occurring as a consequence of respiratory motions and heartbeat. Image-guided feedback drives a gimbaled radiation accelerator (maximum 15 x 15 cm field size) capable of real-time &#177;4 cm pan-and-tilt action. Robot-driven &#177;60&#176; pivots of an integrated &#177;185&#176; rotational gantry allow for coplanar and non-coplanar accelerator beam set-up angles, ultimately permitting unique treatment degrees of freedom. State-of-the-art software aids real-time six dimensional positioning, ensuring irradiation of cancer targets with sub-millimeter accuracy (0.4 mm at isocenter). Use of these features enables treating physicians to steer radiation dose to cancer tumor targets while simultaneously reducing radiation dose to normal tissues. By adding respiration correlated computed tomography (CT) and 2-[18F] fluoro-2-deoxy-&#7429;-glucose (18F-FDG) positron emission tomography (PET) images into the planning system for enhanced tumor target contouring, the likelihood of physical tumor miss becomes substantially less1. In this article, we describe new radiation plans for the treatment of moving lung tumors.

Stereotactic ablative body radiation therapy (SBRT) involves the precise delivery of high-dose radiation to cancer tumor targets. A novel SBRT platform offers a first-of-its-kind gimbaled radiation accelerator mounted within a pivoting O-ring gantry capable of dynamic image-guided tumor tracking. Here, we describe dynamic tumor tracking for lung targets.

Physicians considering stereotactic ablative body radiation therapy (SBRT) for the treatment of extracranial cancer targets must be aware of the sizeable ...

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 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 Lower Body Positive Pressure Treadmill for Knee Osteoarthritis Rehabilitation

Here, based on a clinician&rsquo;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in addition to a clinical, functional assessment methodology, including details for further encouragement of the development of non-drug surgical intervention strategies in knee osteoarthritis patients. However, we only present the effect of LBPP training in improvement of pain and knee function in one patient through three-dimensional gait analysis. The exact, long-term effects of this approach should be explored in future studies.

Here, based on a clinician&#8217;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in addition to a clinical, functional assessment methodology, including details for further encouragement of the development of non-drug surgical intervention strategies in knee osteoarthritis patients. However, we only present the effect of LBPP training in improvement of pain and knee function in one patient through three-dimensional gait analysis. The exact, long-term effects of this approach should be explored in future studies.

Here, based on a clinician&rsquo;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in ...

A Rat Carotid Artery Pressure-Controlled Segmental Balloon Injury with Periadventitial Therapeutic Application

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the luminal surface area in arteries thereby reducing adequate blood flow to organs and distal tissues. Clinically, revascularization procedures such as balloon angioplasty with or without stent placement aim to restore blood flow. Although these procedures reestablish blood flow by reducing plaque burden, they damage the vessel wall, which initiates the arterial healing response. The prolonged healing response causes arterial restenosis, or re-narrowing, ultimately limiting the long-term success of these revascularization procedures. Therefore, preclinical animal models are integral for analyzing the pathophysiological mechanisms driving restenosis, and provide the opportunity to test novel therapeutic strategies. Murine models are cheaper and easier to operate on than large animal models. Balloon or wire injury are the two commonly accepted injury modalities used in murine models. Balloon injury models in particular mimic the clinical angioplasty procedure and cause adequate damage to the artery for the development of restenosis. Herein we describe the surgical details for performing and histologically analyzing the modified, pressure-controlled rat carotid artery balloon injury model. Additionally, this protocol highlights how local periadventitial application of therapeutics can be used to inhibit neointimal hyperplasia. Lastly, we present light sheet fluorescence microscopy as a novel approach for imaging and visualizing the arterial injury in three-dimensions.

The rat carotid artery balloon injury mimics the clinical angioplasty procedure performed to restore blood flow in atherosclerotic vessels. This model induces the arterial injury response by distending the arterial wall, and denuding the intimal layer of endothelial cells, ultimately causing remodeling and an intimal hyperplastic response.

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the ...

Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. The baroreflex is a key homeostatic mechanism to counteract acute, short-term changes in arterial BP and to maintain BP in a relatively narrow physiological range. BP is sensed by baroreceptors located in the aortic arch and carotid sinus. When BP changes, signals are transmitted to the central nervous system and are then communicated to the parasympathetic and sympathetic branches of the autonomic nervous system to adjust HR. A rise in BP causes a reflex decrease in HR, a drop in BP causes a reflex increase in HR.
Baroreflex sensitivity (BRS) is the quantitative relationship between changes in arterial BP and corresponding changes in HR. Cardiovascular diseases are often associated with impaired baroreflex function. In various studies reduced BRS has been reported in e.g., heart failure, myocardial infarction, or coronary artery disease. 
Determination of BRS requires information from both BP and HR, which can be recorded simultaneously using telemetric devices. The surgical procedure is described beginning with the insertion of the pressure sensor into the left carotid artery and positioning of its tip in the aortic arch to monitor arterial pressure followed by the subcutaneous placement of the transmitter and ECG electrodes. We also describe postoperative intensive care and analgesic management. After a two-week period of post-surgery recovery long-term ECG and BP recordings are performed in conscious and unrestrained mice. Finally, we include examples of high-quality recordings and the analysis of spontaneous baroreceptor sensitivity using the sequence method.

The baroreflex is a heart-rate regulation mechanism by the autonomic nervous system in response to blood-pressure changes. We describe a surgical technique to implant telemetry transmitters for continuous and simultaneous measurement of electrocardiogram and blood pressure in mice. This can determine spontaneous baroreflex sensitivity, an important prognostic marker for cardiovascular disease.

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. ...

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism

Lung transplantation (LTx) remains the standard of care for end-stage lung disease. A shortage of suitable donor organs and concerns over donor organ quality exacerbated by excessive geographic transportation distance and stringent donor organ acceptance criteria pose limitations to current LTx efforts. Ex situ lung perfusion (ESLP) is an innovative technology that has shown promise in attenuating these limitations. The physiologic ventilation and perfusion of the lungs outside of the inflammatory milieu of the donor body affords ESLP several advantages over traditional cold static preservation (CSP). There is evidence that negative pressure ventilation (NPV) ESLP is superior to positive pressure ventilation (PPV) ESLP, with PPV inducing more significant ventilator-induced lung injury, pro-inflammatory cytokine production, pulmonary edema, and bullae formation. The NPV advantage is perhaps due to the homogenous distribution of intrathoracic pressure across the entire lung surface. The clinical safety and feasibility of a custom NPV-ESLP device have been demonstrated in a recent clinical trial involving extender criteria donor (ECD) human lungs. Herein, the use of this custom device is described in a juvenile porcine model of normothermic NPV-ESLP over a 12 h duration, paying particular attention to management techniques. Pre-surgical preparation, including ESLP software initialization, priming, and de-airing of the ESLP circuit, and the addition of anti-thrombotic, anti-microbial, and anti-inflammatory agents, is specified. The intraoperative techniques of central line insertion, lung biopsy, exsanguination, blood collection, cardiectomy, and pneumonectomy are described. Furthermore, particular focus is paid to anesthetic considerations, with anesthesia induction, maintenance, and dynamic modifications outlined. The protocol also specifies the custom device's initialization, maintenance, and termination of perfusion and ventilation. Dynamic organ management techniques, including alterations in ventilation and metabolic parameters to optimize organ function, are thoroughly described. Finally, the physiological and metabolic assessment of lung function is characterized and depicted in the representative results.

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism

This paper describes a porcine model of negative pressure ventilation ex situ lung perfusion, including procurement, attachment, and management on the custom-made platform. Focus is made on anesthetic and surgical techniques, as well as troubleshooting.

Lung transplantation (LTx) remains the standard of care for end-stage lung disease. A shortage of suitable donor organs and concerns over donor organ ...

Evaluation of a Point-of-Care Testing Analyzer for Measuring Peripheral Blood Leukocytes

White blood cell (WBC) is an important indicator of inflammation in the body, and it can help distinguish between bacterial and viral infections. At present, most primary medical institutions in China have a poor percentage of adoption of blood-testing technology, and a hematology detection system with a high price to performance ratio and easy operation is urgently needed in primary healthcare centers. This paper introduces the principle and operation procedures of a point-of-care testing (POCT) card-based leukocyte analyzer (evaluated system), which was used to detect WBC indexes such as neutrophils, lymphocytes, and intermediate group cells (including eosinophils, basophils, and monocytes) in whole blood. The results from the evaluated system were compared to those from two commercial automatic hematology analyzers (reference system). The correlation and consistency between the evaluated system and the commercial reference systems were analyzed. The results showed that WBC count and number of granulocytes detected by the evaluated and reference systems showed a strong positive correlation (rs = 0.972 and 0.973, respectively), while the number of lymphocytes showed a relatively low correlation (rs = 0.851). A Bland-Altman plot showed that the major difference between the values detected by the evaluated system and the reference systems is within 95% limits of agreement (LoA), indicating that the two systems are in good agreement. In conclusion, the evaluated system has an excellent correlation, robust consistency, and a reliable comparison with the results of the widely used automatic hematology analyzers. It is ideal for WBC detection in primary medical institutions where a full-automatic five-category hematology analyzer is unavailable, especially during the COVID-19 normalized prevention and control period.

A protocol to measure peripheral blood leukocytes using a POCT card-based leukocyte analyzer is presented here. Same blood samples were tested by two automated hematology analyzers to evaluate the consistency and accuracy of the results. The results showed that the evaluated analyzer had a good correlation with the reference system.

White blood cell (WBC) is an important indicator of inflammation in the body, and it can help distinguish between bacterial and viral infections. At ...

A Method for Zanba-Stir-Fried Tiebangchui Process Optimization

Optimization of Processing Technology for Tiebangchui with Zanba Based on CRITIC Combined with Box-Behnken Response Surface Method

The dried root of Aconitum pendulum Busch., called Tiebangchui (TBC) in Chinese, is one of the most famous Tibetan medicines. It is a widely used herb in northwest China. However, many cases of poisoning have occurred because of TBC's intense toxicity and because its therapeutic and toxic doses are similar. Therefore, finding a safe and effective method to reduce its toxicity is an urgent task. A search through the Tibetan medicine classics shows that the processing method of TBC stir-fried with Zanba was recorded in the "Processing specification of Tibetan medicine of Qinghai Province (2010)". However, the specific processing parameters are not yet clear. Thus, this study aims to optimize and standardize the processing technology of Zanba-stir-fried TBC.
First, a single-factor experiment was conducted on four factors: the slice thickness of TBC, amount of Zanba, processing temperature, and time. With monoester and diester alkaloid contents in Zanba-stir-fried TBC as indexes, CRITIC combined with the Box-Behnken response surface method was used to optimize the processing technology of Zanba-stir-fried TBC. The optimized processing conditions of Zanba-stir-fried TBC were a TBC slice thickness of 2 cm, three times more Zanba than TBC, a processing temperature of 125 &#176;C, and 60 min of stir-frying. This study determined the optimized and standard processing conditions for the usage of Zanba-stir-fried TBC, thus providing an experimental basis for the safe clinical use and industrial production of Zanba-stir-fried TBC.

Author Spotlight: Optimization of Processing Technology for Tiebangchui with Zanba Based on CRITIC Combined with Box-Behnken Response Surface Method  

The present protocol describes an efficient and standard detoxification processing method for Zanba-stir-fried Tiebangchui using CRITIC combined with the Box-Behnken response surface method.

The dried root of Aconitum pendulum Busch., called Tiebangchui (TBC) in Chinese, is one of the most famous Tibetan medicines. It is a widely used herb in ...