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At least 19 recordsLinked to original sources
PubMed1979

Tissue perfusion inhomogeneity during early tumor growth in rats.

Tissue perfusion in BA 1112 sarcomas of WAG inbred Rijswijk rats was determined from in vivo measurements of capillary density, length, and erythrocyte velocity in modified Algire chamber preparations. Studies were done with the use of television techniques in situ during a period of 26 days, both in control chambers and after implantation of a 0.1-mm3 piece of tumor tissue. Perfusion in control areas void of tumor tissue. Perfusion in control areas void of tumor was approximately 8-10 ml/minute/100 g of tissue. Flow in active tumor growth regions on the outward side of the tumor edge was through undifferentiated channels and had characteristics of flow through a porous medium. Despite enhanced arterial supply, the stabilized tumor microcirculation at the inward side of the growing tumor retained its perfusion rate constant (15-18 ml/min/100 g). Perfusion in central portions of the tumor was about 2-4 ml/minute/100 g during 12 days, whereas the tumor doubled in diameter. Our findings support the concept of temporal and functional blood flow inhomogeneity in the microcirculation of spreading tumors.

Animals↗
PubMedDate not supplied

Skeletal muscle PO2: indicator of peripheral tissue perfusion in haemorrhagic shock.

The following conclusions can be made on the basis of this work: 1) Measurements of skeletal muscle oxygen tension provide an excellent index of tissue perfusion in haemorrhagic shock. 2) Correction of cardiac output and arterial blood oxygen tension in haemorrhagic shock does not necessarily ensure normal tissue oxygenation. 3) In haemorrhagic shock adequate replacement of blood loss using a balanced salt solution in addition to blood replacement is an integral part of the fluid management. 4) Correction of hypovolemia with an equivalent volume of a plasma expander and subsequent reinfusion of shed blood also returns tissue perfusion to normal. However, this treatment results in marked haemodilution and correction of extracellular fluid loss remains inadequate.

Abdominal Muscles↗
PubMed1978

Cardiac and renal prostaglandin I2. Biosynthesis and biological effects in isolated perfused rabbit tissues.

Both the isolated perfused rabbit heart and kidney are capable of synthesizing prostaglandin (PG) I(2). The evidence that supports this finding includes: (a) radiochemical identification of the stable end-product of PGI(2), 6-keto-PGF(1alpha), in the venous effluent after arachidonic acid administration; (b) biological identification of the labile product in the venous effluents which causes relaxation of the bovine coronary artery assay tissue and inhibition of platelet aggregation; and (c) confirmation that arachidonic acid and its endoperoxide PGH(2), but not dihomo-gamma-linolenic acid and its endoperoxide PGH(1), serve as the precursor for the coronary vasodilator and the inhibitor of platelet aggregation. The rabbit heart and kidney are both capable of converting exogenous arachidonate into PGI(2) but the normal perfused rabbit kidney apparently primarily converts endogenous arachidonate (e.g., generated by stimulation with bradykinin, angiotensin, ATP, or ischemia) into PGE(2); while the heart converts endogenous arachidonate primarily into PGI(2). Indomethacin inhibition of the cyclo-oxygenase unmasks the continuous basal synthesis of PGI(2) by the heart, and of PGE(2) by the kidney. Cardiac PGI(2) administration causes a sharp transient reduction in coronary perfusion pressure, whereas the intracardiac injection of the PGH(2) causes an increase in coronary resistance without apparent cardiac conversion to PGI(2). The perfused heart rapidly degrades most of the exogenous endoperoxide probably into PGE(2), while exogenous PGI(2) traverses the heart without being metabolized. The coronary vasoconstriction produced by PGH(2) in the normal perfused rabbit heart suggests that the endoperoxide did not reach the PGI(2) synthetase, whereas the more lipid soluble precursor arachidonic acid (exogenous or endogenous) penetrated to the cyclooxygenase, which apparently is tightly coupled to the PGI(2) synthetase.

Animals↗
PubMed1977

Simultaneous fixation and production of catecholamine fluorescence in central nervous tissue by perfusion with aldehydes.

Perfusion with a mixture of formaldehyde (4%) and glutaraldehyde (0.5%) is shown both to fix central nervous tissue and to produce, with no further treatment, a fluorescence histochemical localization of catecholamines. After perfusion, serial sections can be readily taken through the whole brain with a Vibratome. Landmarks which are apparent at low power with white-light illumination can be seen when the sections are viewed in the fluorescence microscope. Catecholamine-containing nerve cell bodies, varicose axon terminals and non-varicose nerve fibres appear brightly fluorescent and well localized. The method has been applied to rats, guinea-pigs and rabbits and is ideally suited to the accurate mapping of central catecholamine neurons and their processes.

Animals↗
PubMed1979

Ischaemic neuropathy in uraemic patients caused by bovine arteriovenous shunt.

A bovine shunt, inserted between the radial artery and cephalic vein in the upper arm for access during chronic haemodialysis, caused a distal, ischaemic neuropathy in two patients. There were electrophysiological signs of axonal degeneration of motor and sensory nerve fibres in the patient with severe ischaemia, and, of only sensory fibres in the patient with mild ischaemia. Thenar muscle blood flow studies using 133Xe were a useful measure of altered tissue perfusion. Recovery was incomplete in both cases, despite banding of the graft and improved tissue perfusion in the severe case.

Action Potentials↗
PubMed1979

Measurement of tissue pH in skin by glass microelectrodes.

Alterations in metabolic activity may be used as an indicator of tissue perfusion and haemodynamic status in peripheral ischaemia. A new type of microelectrode was used to measure pH in the skin of patients with vascular disease, and a decrease in pH was demonstrated along the leg, commensurate with the severity of the disease. Measurement of skin pH by this technique is easy and may be useful for assessing tissue perfusion or skin viability in other conditions.

Glass↗
PubMed1978

In vitro release of [5-methionine]enkephalin and [5-leucine]-enkephalin from the rat globus pallidus.

Endogenous [5-methionine]enkephalin (Metenkephalin) and [5-leucine]enkephalin (Leu-enkephalin) are released from perfused slices of rat globus pallidus by increased K(+) in a Ca(2+)-dependent manner. Tissue perfused for 40 min contained only 26% of the Met-enkephalin and 44% of the Leu-enkephalin found in the freshly dissected tissue. After perfusion, the mean (+/-SEM) ratio (wt/wt) of Met-enkephalin to Leu-enkephalin was 3.4 +/- 0.2 compared with 5.8 +/- 0.2 in the fresh tissue. The degradation of trace amounts of synthetic [(3)H]enkephalins in the perfusing medium during stimulated release seems to reflect the accelerated degradation of enkephalin released from the tissue: 63% of the Met-enkephalin and 23% of the Leu-enkephalin were degraded in a medium containing bacitracin (30 mug/ml). The mean ratio (wt/wt) of the Met-enkephalin to the Leu-enkephalin recovered after release by exposure of slices to 50 mM K(+) was 2.7 +/- 0.3. When perfusates were corrected for degradation, this ratio increased to about 5.5 which is higher than that found in the perfused tissue. The differences in release, tissue loss, and catabolism of the two enkephalins may be reflecting differences in the metabolic systems operating on the pentapeptides, but this interpretation will have to be validated by in vivo release experiments. In any event these observations strongly suggest that both enkephalins can be considered candidate neurotransmitters in the rat globus pallidus.

Animals↗
PubMedDate not supplied

Quantitative measurement of local blood flow with heat clearance.

Measurements of the local blood flow through organs by means of heated thermistor-probes enable one to perform continuous recordings of flow. The principle is based on the measurement between a heated and an unheated probe, both implanted in the tissue or placed on the superficial layer of the organ. The flow-measure for this type of blood flow recording is the heat transported from the heated site of the tissue. It is measured in cal-cm(-1)-sec(-1)-degree C(-1). This is the dimension of the heat conductance. Quantification of continuous blood flow measurements in ml flow/g tissue-min has been carried out with combinations of gas clearance and heat transport. It has now become possible to measure blood flow in ml blood-ml(-1) tissue-min(-1) solely with the aid implanted thermistors. Two types of local blood flow measurements are described. 1. Measurements with "slug heating" by which a thermistor is heated for a very short time and the temperature change is subsequently recorded. 2. The measurement of flow by sudden introduction of heat, if a heating coil around a micro-thermistor is switched on or off and the course of the tissue temperature is subsequently followed. It is proven, that the temperature of a point-shaped micro-thermistor in nonperfused tissue and in homogeneous perfused tissue differs only by an exponential factor (see article) where uslug is the temperature field after a slug injection of heat dependent on location, time, blood flow (phi) and partition coefficient for heat (lambda) and where index 0 = unperfused tissue. If the heater is not heated in the form of a delta function but is switched on and the temperature is subsequently recorded or if the heater, after a period of constant temperature, is switched off, the derivatives in respect to time differ only by an exponential factor and can be used as a measure of flow. The evaluation of blood flow is described in detail. The measurements show the following advantages, compared with former techniques: 1. Heat clearance and continuous blood flow measurements by means of heat transport measurements are both possible at the same site. 2. No other operation and procedures are necessary except implantation of the thermistor. 3. Turning on the heater does not affect the tissue and does not cause emotional reactions. As examples the measurements of local blood flow in brain tissue and in the myocardium of conscious animals are described.

Animals↗
PubMed1979

Release of gastrin from the skeletal muscles and from the antral mucosa in cats induced by sulfonuric drugs.

The present observations indicate that sulfonuric drugs release gastrin both from peripheral nerves in striated muscles and from endocrine-like cells in the gastrointestinal tract. Gastrin appears in perfusates of extirpated cat legs after administration of tolbutamide or glibenclamide (5-50 mg/kg or 5-500 microgram/kg perfused tissue respectively) to the perfusion medium. Furthermore gastrin is released into the portal vein of cats after i.v. administration of glibenclamide (5-50 microgram/kg). The finding that sulfonuric drugs not only release insulin from beta-cells in the pancreas, but also gastrin from gastrin producing cells in the stomach as well as from nerve fibers in the skeletal muscles, indicate that sulfonuric drugs have more wide spread effects than previously assumed. Possible consequences of the drug induced release of peptides from peripheral nerves as well as of the release of gastrin from the gastrointestinal tract are discussed.

Animals↗
PubMed1975

The problem of tissue oxygenation in diabetes mellitus. I. Its relation to the early functional changes in the microcirculation of diabetic subjects.

The underlying cause leading to the reversible functional changes in the microcirculation of insulin-dependent diabetic subjects early during the disease prior to any clinical signs of retinopathy and nephropathy (functional microangiopathy) is discussed. It is suggested that the initial microvascular dilation observed in diabetics is due to an autoregulatory response to relative tissue hypoxia providing an increased tissue perfusion in order to improve tissue oxygen delivery. Supporting evidence for this suggestion is derived from the findings that diabetics simultaneously may show increased tissue oxygen consumption and decreased ability of the circulating blood to release oxygen to the tissues. The latter defect is likely to be caused by two interrelated factors: 1. an increased proportion of haemoglobin A1c with high oxygen affinity, and 2. difficulties of maintaining a sufficiently high concentration of plasma inorganic phosphate in order to provide an optimal 2,3-diphosphoglycerate (2,3-DPG) content in the erythrocytes. The basal oxygen demand of diabetics may fluctuate even within a few hours dependent upon the state of metabolic control and is increased at times of poor regulation. Hence, diabetics may suffer from innumerable cellular hypoxic injuries, which during the first years of the disease are counteracted in the microcirculation by an autoregulatory response. These microvascular reactions associated with increased plasma permeation may over the years be of major importance for the development of the degenerative microangiopathy in diabetes.

Diabetes Mellitus↗
PubMed1975

The influence of pulsatile perfusion on oxygen uptake by the isolated canine hind limb.

The possible advantages of pulsatile over continuous blood flow have intrigued cardiac surgeons for years. This issue may have clinical significance for moderate to long cardiopulmonary bypass procedures. In spite of aggressive investigation, this problem remains controversial. A system permitting perfusion of an isolated canine hind limb with constant flow, Pao2, Paco2, oxygen delivery, temperature, and pHa but variable stroke volume was established. Under stable conditions, oxygen uptake by the limb was constant over a wide range of stroke volumes. Regression equations relating oxygen uptake to stroke volume were calculated and found to have a near zero slope. When the hydrogen ion concentration of the blood perfusing tissue is held constant, the oxygen consumption of that tissue is independent of the pulsatile nature of the perfusing blood.

Animals↗
PubMed1977

Physiological principles of therapy in head and neck cutaneous wounds.

It is essential that surgeons treating soft tissue wounds about the head and neck have a basic understanding of skin anatomy and physiology. The quality as well as the rate of healing is usually dependent on the type and extent of the original injury. Having a practical working knowledge of the pathophysiology of the various types of head and neck soft tissue injuries allows an intelligent choice of the most appropriate approach to a particular wound. The best functional and cosmetic results routinely are achieved by the wound's undergoing primary healing. Skin tapes and various sutures each exhibit certain benefits and disadvantages in primary closure of wounds. Skin tapes cause less inflammatory reaction but fail to close the subepithelial wound spaces. The inflammatory reaction and subsequent scarring caused by the various sutures depends upon the size of the suture needle, the diameter of the suture material and whether it is a monofilament or a woven suture. The essential nutrition of the wound must be maintained with the body providing adequate amounts of carbohydrates, proteins, trace elements and vitamins. The lack of adequate wound tissue perfusion by a normal or reversed oxygen gradient will lead to tissue necrosis and infection. The size of the inoculum of micro-organisms, the virulence of the organisms and host antimicrobial defense mechanisms determine if an infection will develop. The pharmacological action of each antibiotic must be understood in order to choose the proper antibiotic, its route of administration and to avoid unwanted side effects. Crushing tissue injuries, high velocity projectile tissue injuries and major burns of tissue may require several days to exhibit the true scope of the original injury. Most of these injuries must be treated by the open delayed method of wound treatment until the proper tissue conditions exist for healing. The proper timing and correct choice of autografts and tissue flaps from the surgeon's personal experience, study and conferring with other qualified surgeons. Upon gaining insight into the cellular and humoral antimicrobial defense system, the surgeon is able to provide the best conditions to allow these systems to function properly. Studies in the ultrastructures of skin along with the recently developed microbioassay techniques will allow a closer monitoring during the process of wound healing that will provide the basis for future techniques in the beneficial manipulation of wound healing.

Anti-Bacterial Agents↗