Capillary perfusion system

Capillary Perfusion System for Quantitative Evaluation of Protein Adsorption and Platelet Adhesion to Artificial Surfaces... 

A capillary perfusion system has been developed for in vitro quantitation of protein adsorption and platelet accumulation on artificial surfaces under controlled... 

Figure 1 Schematic diagram cf the in vitro capillary perfusion system. S 50 ml plastic syringe containing protein or antibody solution, antiocagulated whole blood or washed platelet suspension P piston driven by syringe pump SC 3-v ay stop-cock J joint in silicone tubing C glass capillary (C.80 or 0.56 mm i.d.) F direction of blood flow T plastic tube for blood collection R rinsing buffer from a reservoir at 37 C, flow controlled by a peristaltic pump. The entire apparatus is enclosed in a thermostatec hood at 37 C.

Platelet adhesion to subendothelium at high wall shear rate has been shown to be mediated by vWF ( ), Preliminary results in the capillary perfusion system, using glass capillaries uncoated or coated with purified humian albumin or bovine collagen, showed an increase in platelet deposition in the presence of vWF on the albumin surface at low... 

In summary, the capillary perfusion system represents a simple in vitrc technique for the quantitation of protein adsorption and platelet accumulation on artificial surfaces under well defined hydrodynamic conditions (0-4.,000 s ). Radioisotopic methods enable simultaneous study of platelet deposition and adsorption of one or more plasma proteins. Experiments may be performed using washed platelet suspensions or anticoagulated whole blood, platelet deposition being measured in the latter case by surface phase radioimmunoassay with a... 

Flow Properties of Perfusion System. Under conditions of Poiseuille type laminar flow in capillary tubes, the Reynold s number (R ) is given b the relation ... 

Pulmonary hypertension develops late in the course of COPD, usually after the development of severe hypoxemia. It is the most common cardiovascular complication of COPD and can result in cor pulmonale, or right-sided heart failure. Hypoxemia plays the primary role in the development of pulmonary hypertension by causing vasoconstriction of the pulmonary arteries and by promoting vessel wall remodeling. Destruction of the pulmonary capillary bed by emphysema further contributes by increasing the pressure required to perfuse the pulmonary vascular bed. Cor pulmonale is associated with venous stasis and thrombosis that may result in pulmonary embolism. Another important systemic effect is the progressive loss of skeletal muscle mass, which contributes to exercise limitations and declining health status. 

Two different circulatory systems, the bronchial and the pulmonary, supply the lungs with blood [133], The bronchial circulation is a part of the systemic circulation and is under high pressure. It receives about 1% of the cardiac output and supplies the conducting airways, pulmonary blood vessels and lymph nodes [133], It is important for the distribution of systemically administered drugs to the airways and to the absorption of inhaled drugs from the airways [18]. The pulmonary circulation comprises an extensive low-pressure vascular bed, which receives the entire cardiac output. It perfuses the alveolar capillaries to secure efficient gas exchange and supplies nutrients to the alveolar walls. Anastomoses between bronchial and pulmonary arterial circulations have been found in the walls of medium-sized bronchi and bronchioles [18, 65, 67],... 

Distribution is the delivery of drug from the systemic circulation to tissues. Once a drug has entered the blood compartment, the rate at which it penetrates tissues and other body fluids depends on several factors. These include (1) capillary permeability, (2) blood flow-tissue mass ratio (i.e., perfusion rate), (3) extent of plasma protein and specific organ binding, (4) regional differences in pH, (5) transport mechanisms available, and (6) the permeability characteristics of specific tissue membranes. 

The deposition of plasmids after systemic administration is restricted to the intravascular space due to its low microvascular permeability in most organs with continuous capillary bed. Some organs with fenestrated capillaries, such as liver, spleen, and bone marrow, provide some opportunities for extravasation of plasmids. Intravenously injected plasmids initially perfuse the pulmonary vascular beds, maximizing the... 

Extensive burn injuries produce a systemic response that pulls fluid from the vascular system into the interstitial space. This is exacerbated in burns greater than 20% TBSA by a significant capillary leak into the microvasculature and generalized edema. Without proper treatment, intravascular fluid loss and hypovolemic burn shock result. This is why immediate initiation of fluid resuscitation is important. A successful fluid resuscitation will maintain intravascular volume and organ perfusion until capillary membrane integrity is restored (approximately 24 to 48 hours postinjury). 

The blood flow is important in carrying the absorbed drug from the absorption site to the systemic circulation. A large network of capillaries and lymphatic vessels perfuse the duodenal region and peritoneum. The splanchnic circulation receives about 28% of the... 

The above-mentioned studies have suggested or proposed a direct renal injury by IL-2, but none of them have been able to conclusively distinguish a direct IL-2 renal effect from simple renal under-perfusion severe enough to cause ischemia and ATN. The toxicity of IL-2 has been dearly assodated with widespread endothelial cell damage and capillary leak [25]. This is consistent with a generahzed, systemic effect of IL-2 rather than proof of a specific direct effect on the kidney. 

Markers of physiological effects can be useful in identifying early changes in respiratory functions of the lung due to inhaled material. Biomarkers are available to measure lung mechanical properties, ventilation, expiratory flow, intrapulmonary gas distribution, alveolar-capillary gas exchange, and perfusion. Such measurements have been used to test the effects of exposure to an array of inhaled toxicants. These assays can reveal functional manifestation of structural changes in the respiratory system, whether... 

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