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Biomedical subjects

P Chapchap

Publications and source records attributed to P Chapchap.

9 recordsLinked to original sources
PubMed1991

Improved method of porcine renal allografting for transplantation research.

This study presents a refined, reproducible, and clinically appropriate animal model of renal transplantation. A pair of kidneys are harvested from a donor pig and preserved in Euro-Collins' solution (4 degrees C). After a set period of preservation, the allografts are transplanted to two recipient pigs. The abdomen is entered through a midline incision. The right common iliac artery and vein are dissected and bilateral native nephrectomy is performed. Each allograft is then randomly assigned and transplanted to the recipients. Three minutes before unclamping, 100 mg of furosemide and 10 g of mannitol are given IV. Immediately after reperfusion, urine output is measured for 1 h. The allograft is biopsied and ureteroneocystostomy is created. Cystostomy is then placed using a 16F Foley catheter. The bladder neck is ligated to secure complete diversion of urine, and the abdomen is closed in layers. This kidney transplant model allows an absolutely paired study of the kidney allograft function from the same donor and also collection of pure urine at any time postoperatively, obviating the need for metabolic cages or sedation for urinary collection. This model and its unique modifications allow various transplant studies, including organ preservation, immunosuppressive protocol, and the prevention of reperfusion injury from oxygen free radicals.

Animals↗
PubMed1989

Effect of antiandrogen flutamide on measures of hepatic regeneration in rats.

Male rat liver undergoes a process of demasculinization during hepatic regeneration following partial hepatectomy. The possibility that antiandrogens might potentiate this demasculinization process and in so doing augment the hepatic regenerative response was investigated. Adult male Wistar rats were treated with the antiandrogen flutamide (2 mg/rat/day or 5 mg/rat/day subcutaneously) or vehicle for three days prior to and daily after a 70% partial hepatectomy. At various times after hepatectomy, the liver remnants were removed and weighed. Rates of DNA and polyamine synthesis were assessed by measuring thymidine kinase and ornithine decarboxylase activities, respectively. Hepatic estrogen receptor status and the activity of alcohol dehydrogenase, an androgen-sensitive protein, were measured. Prior to surgery, the administration of 5 mg/day flutamide reduced the hepatic cytosolic androgen receptor activity by 98% and hepatic cytosolic estrogen receptor content by 92% compared to that present in vehicle-treated controls. After hepatectomy, however, all differences in sex hormone receptor activity between the treatment groups were abolished. The rate of liver growth after partial hepatectomy in the three groups was identical. Moreover, hepatectomy-induced increases in ornithine decarboxylase activity and thymidine kinase activity were comparable. These data demonstrate that, although flutamide administration initially alters the sex hormone receptor status of the liver, these affects have no effect on the hepatic regenerative response following a partial hepatectomy.

Alcohol Dehydrogenase↗
PubMed1988

Liver regeneration in rats treated with the antiandrogen flutamide.

Previous studies have shown that male rat liver undergoes demasculinization during hepatic regeneration after partial hepatectomy. In the present study the effect of the antiandrogen flutamide on liver regeneration was assessed. Adult male Wistar rats were treated with flutamide (2 mg/rat/day or 5 mg/rat/day subcutaneously) or vehicle for 3 days prior to and daily after partial hepatectomy. Rates of DNA and polyamine synthesis were assessed by measuring thymidine kinase and ornithine decarboxylase activities, respectively. The rate of liver growth after partial hepatectomy in the three groups was similar at all time points examined. The increases in thymidine kinase activity and ornithine decarboxylase activity after partial hepatectomy were comparable throughout the study. Thus, administration of flutamide did not influence the regenerative response after partial hepatectomy.

Animals↗
PubMed1988

Does hyperprolactinemia affect hepatic regeneration independent of sex steroids?

Prolactin, administered exogenously, has been shown to be trophic to the liver, causing increases in the liver weight-to-body weight ratio. In ornithine decarboxylase activity, and in thymidine kinase activity. To investigate the effect of endogenous hyperprolactinemia on hepatic regeneration, pituitary isografts were placed beneath the renal capsule in rats 2 weeks before the rats underwent a two-thirds partial hepatectomy. Prolactin levels 2 weeks after the transplant were greater in the animals with the pituitary isografts compared with levels in controls. The increase in the liver weight-to-body weight ratio after hepatectomy was similar in the rats with pituitary transplant and the controls. However, chronic hyperprolactinemia was associated with increased basal levels of ornithine decarboxylase activity and thymidine kinase activity. Both ornithine decarboxylase activity and thymidine kinase activity increased after partial hepatectomy, and the magnitude of the changes was similar for both groups of animals. The levels of estrogen receptor activity before the partial hepatectomy and the reduction in receptor activity that follows partial hepatectomy were similar in the two groups of animals. Moreover, the levels of androgen receptor activity within the liver before partial hepatectomy and the increase in receptor activity after hepatectomy were similar in the two groups of animals. Thus, chronic sustained hyperprolactinemia has no beneficial effect on the hepatic regenerative response, despite induction of both basal ornithine decarboxylase and thymidine kinase activities.

Animals↗
PubMed1988

Effect of an antiandrogenic H2 receptor antagonist on hepatic regeneration in rats.

Because biochemical "feminization" of the liver in males is observed with hepatic regeneration and because the hepatic regenerative response in females is greater than that in males, the possibility that antiandrogens might potentiate liver regeneration was investigated. Before 70% hepatectomy, adult male Wistar rats were treated with cimetidine, an antiandrogenic H2 antagonist, at doses up to 10 times greater than those used clinically. Control animals received either the saline vehicle or ranitidine, an H2 antagonist without antiandrogenic properties. Treatment with cimetidine reduced the hepatic cytosolic androgen receptor content compared with ranitidine treatment. Hepatectomy caused a further reduction in androgen receptor activity in all groups. Hepatic cytosolic estrogen receptor activity was comparable in all groups throughout the study. Moreover, the rate of liver growth and the levels of ornithine decarboxylase and thymidine kinase activity induced as part of the regenerative response were similar in all groups. Thus, cimetidine, despite its ability to bind to androgen receptors, and ranitidine, an H2 receptor antagonist without antiandrogen action, do not modulate the hepatic regenerative response to a 70% partial hepatectomy.

Animals↗
PubMed1987

Must fat emulsions and parenteral nutrition solutions be given through separate circuits?

To test the stability of fat emulsions with parenteral nutrition (PN) solutions, 10% soybean fat emulsion (FE) was suspended in PN solutions containing amino acids, electrolytes, vitamins, and different glucose concentrations. Six different mixtures were prepared and analyzed after 15 minutes or 24 hours, under transmission electron microscope: 10% fat emulsion (FE); FE + PN solution with 5% glucose (15 minutes); FE + PN solution with 5% glucose (24 hours); FE + PN with 12.5% glucose (24 hours); FE + PN with 25% glucose (24 hours); and FE + pure glucose 50% (24 hours). The addition of FE to PN solutions containing 5% to 25% glucose did not cause coalescence, aggregation, or confluence of the liposomes or damage to their surface in the first 24 hours after admixture. However, the suspension of fat emulsion in a 50% glucose solution coalesced liposomes and the droplets were nearly all aggregated. We conclude that mixtures of FE with PN solutions with glucose are stable for at least 24 hours and are suitable for clinical use.

Drug Stability↗
PubMed1987

Prolongation of pig-to-dog renal xenograft survival by modification of the inflammatory mediator response.

The pathogenesis of hyperacute renal rejection consists of a nonspecific effector cascade that invokes most of the components of a typical acute inflammatory response. Platelet-activating factor (PAF) represents the most recent and perhaps the most significant mediator and promoting agent of this phenomenon. These studies evaluated SRI 63-441, a novel, synthetic, and the most potent PAF receptor antagonist available, alone and in combination with other prostanoids, for their ability to influence this response and to prolong renal xenograft survival and function in a model of pig-to-dog heterotransplantation. Inhibition of PAF by SRI 63-441 alone, at the dosage and schedule used in these experiments, did not significantly prolong xenograft survival or function. However, the combination of SRI 63-441 with either prostacyclin (PGI2) or prostaglandin E1 (PGE1) infusion demonstrated significant synergism, and resulted in a 6-9-fold increase in kidney survival and a 3-20-fold increase in urine output. Neither PGI2 nor PGE1 infusions alone significantly influenced this xenograft model. Electromagnetic flow studies demonstrated significantly delayed diminution in renal artery blood flow in the combination-treated animals. Serial and end-stage histologic examination of kidneys receiving combination therapy demonstrated a delayed onset of the pathologic deterioration and an overall amelioration of the entire process. These studies demonstrate that significant abrogation of a rapid and violent form of hyperacute rejection can be achieved solely by the pharmacologic manipulation of the inflammatory mediator response.

Alprostadil↗
PubMedDate not supplied

[Liver transplantation in children: initial experience of the Instituto da Criança of the Hospital das Clínicas of Universidade de São Paulo].

The initial experience at the Instituto da Criança do Hospital das Clínicas--School of Medicine of São Paulo University with liver transplantation in children is presented. A staff experienced in the management of children, including pediatric surgeons, hepatologists, critical care specialists, anesthesiologists, and other has been joined to draw therapeutic protocols. Afterward, more than 100 experimental liver transplant were performed in animals of medium size (dogs and pigs). From September, 1989 to July 1991, 12 liver transplants were performed on 9 children (3 retransplants) ranging in age from 2.5 to 17 years, being 5 boys and 4 girls. The donors had been selected according to the ABO blood group and body weight. Just once a blood A+ recipient received a liver from a blood O+ donor. The regular postoperative immunosuppression consisted of triple therapy with cyclosporin, prednisone and azathioprine. The postoperative stay in the Intensive Care Unit ranged from 3 to 24 days, according to the necessity of ventilatory support. These was no intraoperative mortality, arterial or venous thromboses, or early biliary complications. The overall survival is 78% (7/9). Primary non-function of the graft was the cause of death in two of our children. Although the number of cases is still small our results are comparable to those of the best liver transplant centers in the world.

Adolescent↗