[Acute experimental pancreatitis in the opossum. The role of prior truncular vagotomy on the inflammatory response]. / Pancreatitis aguda experimental en el opossum. Rol de la vagotomía troncular previa en la respuesta inflamatoria.

BACKGROUND: Acute pancreatitis (AP) is a common cause of admission to the emergency room. Its etiopathogeny is poorly understood. The pancreatic inflammatory response in this process is unclear. The influence of the autonomic nervous system is a controversial issue. AIMS: To demonstrate the effects of truncular vagotomy on AP due to duodenal distention in the South American opossum. PLACE OF APPLICATION: Department of experimental surgery (Churruca-Visca Hospital) INEUCI (Neuroscience Institute, CONICET, UBA). POPULATION: Male and female South American opossum divided into: a control group (7 animals); group A: truncular vagotomy and pyloroplasty seven days after the onset of AP (7 animals). Group B: truncular vagotomy and pyloroplasty 30 days after provoking AP (7 animals). Group C: truncular vagotomy and pyloroplasty 45 days after the onset of AP (7 animals). METHODS: Acute pancreatitis was caused by duodenal distention of the second portion by inserting a Foley catheter through a gastrostomy. CONCLUSIONS: The method of provoking AP is original. The influence of autonomous nervous system is being underestimated in most of the literature available.

Pancreatitis aguda experimental en el opossum. Rol de la vagotomía troncular previa en la respuesta inflamatoria. / [Acute experimental pancreatitis in the opossum. The role of prior truncular vagotomy on the inflammatory response]

BACKGROUND: Acute pancreatitis (AP) is a common cause of admission to the emergency room. Its etiopathogeny is poorly understood. The pancreatic inflammatory response in this process is unclear. The influence of the autonomic nervous system is a controversial issue. AIMS: To demonstrate the effects of truncular vagotomy on AP due to duodenal distention in the South American opossum. PLACE OF APPLICATION: Department of experimental surgery (Churruca-Visca Hospital) INEUCI (Neuroscience Institute, CONICET, UBA). POPULATION: Male and female South American opossum divided into: a control group (7 animals); group A: truncular vagotomy and pyloroplasty seven days after the onset of AP (7 animals). Group B: truncular vagotomy and pyloroplasty 30 days after provoking AP (7 animals). Group C: truncular vagotomy and pyloroplasty 45 days after the onset of AP (7 animals). METHODS: Acute pancreatitis was caused by duodenal distention of the second portion by inserting a Foley catheter through a gastrostomy. CONCLUSIONS: The method of provoking AP is original. The influence of autonomous nervous system is being underestimated in most of the literature available.

[Acute pancreatitis of uncommon etiology: a physiopathologic approach]. / Pancreatitis agudas de etiologías poco frecuentes: una aproximación fisiopatogénica.

A review of 73 cases of acute pancreatitis (A.P.) of *A in frequent etiology is critically analyzed. The patients were allocated to the following categories: post ingestion of a large meal, dyslipemic, post ERCP, post operative, pregnancy, and puerperium linked., post urlian parotiditis, post stress, idiopathic, drug associated, post traumatic. In each of the above groups those hypotheses that are currently primarily accepted as been mainly concerned with the etiopathogenesis of the inflammatory episode were given preference. One factor upon which the authors has put special emphasis is that of frequent involvement of the nervous system through different types of autonomic are reflexes. This pathogenic mechanism is surprisingly disregarded in the literature. The interrelation ship between the severity of an AP episode and the background provided by the "pancreon" secretory activity is also emphasized. The mortality rate of the whole series was of 7 cases (9.6%). The groups that disclosed the highest rates were related to abdominal surgery (50%) and to dyslipemia (17%).

Pancreatitis agudas de etiologías poco frecuentes: una aproximación fisiopatogénica. / [Acute pancreatitis of uncommon etiology: a physiopathologic approach]

A review of 73 cases of acute pancreatitis (A.P.) of *A in frequent etiology is critically analyzed. The patients were allocated to the following categories: post ingestion of a large meal, dyslipemic, post ERCP, post operative, pregnancy, and puerperium linked., post urlian parotiditis, post stress, idiopathic, drug associated, post traumatic. In each of the above groups those hypotheses that are currently primarily accepted as been mainly concerned with the etiopathogenesis of the inflammatory episode were given preference. One factor upon which the authors has put special emphasis is that of frequent involvement of the nervous system through different types of autonomic are reflexes. This pathogenic mechanism is surprisingly disregarded in the literature. The interrelation ship between the severity of an AP episode and the background provided by the [quot ]pancreon[quot ] secretory activity is also emphasized. The mortality rate of the whole series was of 7 cases (9.6

). The groups that disclosed the highest rates were related to abdominal surgery (50

) and to dyslipemia (17

).

Pancreatitis agudas de etiologías poco frecuentes: una aproximación fisiopatogénica / Acute pancreatitis of uncommon etiology: a physiopathologic approach

Los autores presentan 73 casos de pancreatitis agudas (P.A.) de causas poco frecuentes. Ellas fueron divididas en ingestión copiosa, displémicas, postcolangioretrógrada endoscópica, postoperatorias, tercer trimestre de embarazo, puerperio inmediato, parotídica, por stress e idiopáticas, medicamentosa y por trauma. Se evalúan las teorías etiopatogénicas probables haciendo hincapié en la importancia del Sistema Nervioso Autónomo (S.N.A.) como responsables de las lesiones glandulares. El estado funcional del páncreas, previo al ataque agudo, es uno de los factores predisponentes de mayor envergadura. La mortalidad de la serie fue de 7 casos (9.58 por ciento) siendo las postoperatorias (50 por ciento) y las dislipémicas (16.6 por ciento) las de mayor índice de mortalidad.

Pancreatitis agudas de etiologías poco frecuentes: una aproximación fisiopatogénica / Acute pancreatitis of uncommon etiology: a physiopathologic approach

Los autores presentan 73 casos de pancreatitis agudas (P.A.) de causas poco frecuentes. Ellas fueron divididas en ingestión copiosa, displémicas, postcolangioretrógrada endoscópica, postoperatorias, tercer trimestre de embarazo, puerperio inmediato, parotídica, por stress e idiopáticas, medicamentosa y por trauma. Se evalúan las teorías etiopatogénicas probables haciendo hincapié en la importancia del Sistema Nervioso Autónomo (S.N.A.) como responsables de las lesiones glandulares. El estado funcional del páncreas, previo al ataque agudo, es uno de los factores predisponentes de mayor envergadura. La mortalidad de la serie fue de 7 casos (9.58 por ciento) siendo las postoperatorias (50 por ciento) y las dislipémicas (16.6 por ciento) las de mayor índice de mortalidad. (AU)

Platelet adhesion and aggregation in pulsatile shear flow: effects of red blood cells.

An in vitro test system was developed to examine the effects of red blood cells (RBC) on shear-induced platelet adhesion (SIPAD) and platelet aggregation (SIPAG). Suspensions of human platelets labeled with Mepacrine and suspended in citrated plasma were exposed to single, continuous or repetitive (120-300x) one second shear stress pulses of varying amplitude (15-100 dyn/cm2) in a cone-plate viscometer in the presence or absence of fresh, untreated (intact) RBC or glutaraldehyde (GLA)-fixed, rigid, adenosine diphosphate (ADP)-depleted (GLA)-RBC. SIPAG was expressed as percent loss of single platelets. SIPAD was assessed by measuring the amount of Mepacrine-related fluorescent material remaining on glass disks in the plate of the viscometer after washing with EDTA-saline to remove platelet aggregates. Intact RBC were twice as effective as GLA-RBC in potentiating SIPAG at all shear stress levels. Potentiation of SIPAD by intact RBC was markedly less than that observed with GLA-RBC at stresses below 50 dyn/cm2. These findings are consistent with the concept that while both physical and chemical (ADP) mechanisms are substantially involved in potentiation by RBC of SIPAG, RBC support SIPAD largely by enhancement of platelet transport from the bulk flow to the bounding surfaces. The findings also indicate that it is feasible to assess SIPAD and SIPAG in the same flow system simultaneously. A less complicated version of the method described here should prove useful in the evaluation of patients with platelet functional disorders, and in the evaluation and monitoring of antiplatelet agents.

Evidence for acute renal cortical vasoconstriction after uninephrectomy.

The rate of progression of chronic renal failure (CRF) is similar for many diseases, suggesting a common, perhaps intrinsic, renal signal for its progression. The remnant nephron hypothesis of Bricker suggests that CRF may be the result of persistent compensatory renal growth (CRG). Normally, CRG after unilateral nephrectomy (uniNx) ceases within 1 week. Knowledge of the signals that initiate CRG may therefore shed light on the signals responsible for ongoing CRF. The signals responsible for the initiation of compensatory renal growth after uniNx are unknown. Hemodynamic changes in the remaining renal artery have been observed, but there are as yet no data for the main renal compartment which undergoes hypertrophy, the superficial renal cortex. The noninvasive technique of laser-Doppler flowmetry allows the continuous and independent monitoring of blood velocity and blood volume. The product of the two signals is proportional to tissue blood flow per unit volume of the tissue observed. Under controlled conditions in adult male Sprague-Dawley rats, renal cortical blood velocity increased by 22% within 5 min after uniNx and remained elevated at this level for 60 min. Renal cortical blood volume decreased throughout the experiment. Their product, renal cortical blood flow, increased briefly by 14% 5 min after uniNx but decreased over the time of observation in parallel with renal cortical blood volume. The simultaneous increase in blood velocity and decrease in blood volume in the superficial renal cortex acutely after uniNx suggest that vasoconstriction is an early event in compensatory renal growth.

Effect of chronic oral pentoxifylline administration on murine erythrocyte deformability.

BACKGROUND: Pentoxifylline has been reported to increase radiation sensitivity in vivo. We sought to evaluate whether this effect is mediated by changes in murine erythrocyte flexibility. METHODS: Pentoxifylline was administered via liquid or solid diet to young adult male CF-1 mice for 1-6 weeks. After 1, 3, and 6 weeks of drug administration, plasma levels of pentoxifylline and major derivatives were measured and erythrocyte deformability was assessed by rheoscopy, a technique which permits direct measurement of individual cellular dimensions. RESULTS: Contrary to prior reports, we found no discernible effect of the drug on erythrocyte deformability. CONCLUSIONS: The beneficial effect of pentoxifylline administration on radiation sensitivity in tumor-bearing mice is mediated by other mechanisms.

Pierce-Donachy pediatric VAD: progress in development.

BACKGROUND: Despite the successful use of ventricular assist devices in adults over the past 15 years, relatively little has been done to develop similar devices for pediatric patients. Consequently, no such device is currently available. A review of clinical data suggests that the majority of patients in need of a pediatric ventricular assist device, either for postcardiotomy cardiogenic shock or as a bridge to cardiac transplantation, are neonates weighing 3 to 5 kg. Attempts to "scale down" an adult blood pump to make an appropriate device for these patients have been difficult due to the lack of sufficiently small, commercially available valves and the tendency for thrombus to develop in these small pumps. METHODS: We report on progress in the development of the Pierce-Donachy pediatric ventricular assist device, which incorporates 10-mm-diameter bileaflet valve prototypes. Particle image velocimetry is used to quantify the velocity field inside the pump. RESULTS AND CONCLUSIONS: Particle image velocimetry velocity maps demonstrate the complexity of the flow patterns in these pumps and suggest that improved flow patterns may result from the use of valves with improved hemodynamic performance. Animal tests to determine whether improved flow patterns and better "washing" of the pump's blood-contacting surfaces will reduce thrombus formation are underway.

Concurrent increases in regional hematocrit and blood flow in diabetic rats: prevention by sorbinil.

These studies were undertaken to investigate the relationship between regional hemodynamic and hemorheological changes in the microvasculature of diabetic rats. Diabetes was induced in male Sprague-Dawley rats by injection of streptozotocin (55 mg/kg body wt). Control rats were injected with vehicle (sodium citrate buffer). A subgroup of diabetic rats was treated with an aldose reductase inhibitor (sorbinil) added to the diet in an amount to provide a daily dose of approximately 0.2 mmol.kg-1.day-1. Three weeks later all animals were anesthetized with thiobutabarbital sodium (Inactin, 100 mg/kg injected intraperitoneally) for assessment of blood flow (by injection of 15 microns microspheres) and regional hematocrit (determined by isotope-dilution techniques using 51Cr-labeled red blood cells and 125I-labeled bovine serum albumin) in selected tissues. The hematocrit in arterial blood samples was identical (approximately 46%) in controls and in diabetics. Regional hematocrits were much lower than arterial hematocrits in control rats and ranged from approximately 20% in ocular tissues, sciatic nerve, diaphragm, and skin to approximately 30% in brain, skeletal muscle, heart, and fat. Hematocrits of diabetic rats were markedly increased in ocular tissues, sciatic nerve, and skin but not in brain, heart, or skeletal muscle. These increases in regional hematocrit were associated with increases in blood flow and were largely prevented by sorbinil. Diabetes induced significant decreases in the mean transit times for whole blood and erythrocytes in all tissues examined except brain, retina, and skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Discordant effects of nisoldipine on coronary vascular resistance and permeability changes during reflow after ischemia in isolated rabbit hearts.

Effects of a low dose (5 nM) of nisoldipine on vascular and ventricular function were assessed in isolated rabbit hearts during 2 h of reperfusion after 40 min of global, zero-flow ischemia. External detection of bolus injections of 125I-BSA and pressure data generated during the experiment provided repeated estimates of albumin permeation and vascular hemodynamics (resistance, vascular volume, and fractional rate of intravascular washout of 125I-BSA (k01]. In control hearts perfused continuously for 3.5 h, vascular resistance, vascular volume, LVEDP, and k01 remained constant, while maximum +dP/dt and -dP/dt increased 25% above baseline values, and estimates of albumin permeation increased 1.7 x baseline. Addition of 5 nM nisoldipine to the perfusate after the baseline period produced sustained decreases in vascular resistance (16% vs mean baseline value) without significantly affecting any other parameter. Postischemic perfusion of hearts increased vascular resistance and vascular volume approximately 50% above baseline, decreased k01 by 25% (intravascular washout of 125I-BSA was prolonged), and increased albumin permeation approximately 5 x baseline. While LVEDP remained elevated 3 x baseline, maximum +dP/dt and -dP/dt recovered 100% of baseline values (75-80% of untreated control values at comparable time points). Addition of 5 nM nisoldipine to the perfusate prior to ischemia prevented the increased vascular resistance during reflow, prevented the decrease in k01 and the increase in vascular volume, but did not affect the increased albumin permeation and, in general, did not affect the rate of recovery of left ventricle function. These results indicate that a low dose of nisoldipine preserves postischemic coronary vascular hemodynamics, but has little or no effect on the increased vascular leakage of albumin.

Reduction of the surface-volume ratio: a physical mechanism contributing to the loss of red cell deformability in malaria.

Plasmodia and other intraerythrocytic parasites reduce the deformability of the red cells they infect. One mechanism potentially responsible for this reduction in deformability is the decrease in the surface:volume (S/V) ratio of the red cell which occurs with parasite growth. To examine this hypothesis, normal red cells were allowed to phagocytize polylysine-coated latex spheres 1.0 to 2.9 microns in diameter. Deformability decreased progressively with spheres of increasing size, consistent with the decreasing S/V ratios of those cells (from an initial length:width [L/W] ratio of 2.398 +/- 0.549 for normal red cells to 1.559 +/- 0.249 for red cells containing 2.92 microns latex spheres at 40 dynes per cm2, p less than 0.001). Nevertheless, red cells containing latex spheres 2.0-2.9 microns in diameter remained deformable and continued to tank tread, in contrast to red cells containing Plasmodium falciparum parasites of that size, which are not deformable and do not tank tread. The progressive decrease in S/V produced by the latex spheres is consistent with their effect on the L/W ratio. However, the total loss of deformability observed with red cells containing parasites of similar or smaller size cannot be explained on these grounds alone. It suggests an additional mechanism, such as calcium-induced crosslinking of the red cell cytoskeleton.