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Biomedical subjects

K A Porter

Publications and source records attributed to K A Porter.

At least 55 records · Page 3Linked to original sources
PubMed1985

The effect of portacaval shunt on hepatic lipoprotein metabolism in familial hypercholesterolemia.

The hyperlipidemia observed in familial hypercholesterolemia can be reduced by portacaval anastomosis. We report the effects of a portacaval shunt on hepatic morphology and biosynthetic pathways crucial to hepatic cholesterol homeostasis in homozygous receptor-negative familial hypercholesterolemia. Portacaval anastomosis was associated with a dramatic change in hepatocyte morphology, 28% reduction in plasma low-density lipoprotein concentration, and a decrease in hepatic total and free cholesterol content by 27 and 75%, respectively. Furthermore, the rate-limiting enzyme in cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A reductase was decreased by 56%. Finally, the reduced binding of low-density lipoproteins to hepatic membranes preoperatively was increased following the portacaval shunt. These combined results indicate that the changes in circulating lipoprotein concentrations observed after portacaval shunt are due to alterations in the metabolic consequences of the defective recognition of low-density lipoproteins by the liver of familial hypercholesterolemic subjects.

Adult↗
PubMed1984

Reversibility of lymphomas and lymphoproliferative lesions developing under cyclosporin-steroid therapy.

Post-transplant lymphomas or other lymphoproliferative lesions, which were usually associated with Epstein-Barr virus infections, developed in 8, 4, 3, and 2 recipients, respectively, of cadaveric kidney, liver, heart, and heart-lung homografts. Reduction or discontinuance of immunosuppression caused regression of the lesions, often without subsequent rejection of the grafts. Chemotherapy and irradiation were not valuable. The findings may influence policies about treating other kinds of post-transplantation neoplasms.

Adolescent↗
PubMed1983

Reversal of hepatic alpha-1-antitrypsin deposition after portacaval shunt.

End-to-side portacaval shunts were carried out in three children with the liver disease of alpha-1-antitrypsin deficiency and complications of portal hypertension. Their clinical courses have been stable for 3 1/2 to almost 7 years. Postoperative liver biopsy material from two of the patients showed the typical histopathological changes caused by portal diversion, as well as an apparent reduction in the quantity of alpha-1-antitrypsin particles in the hepatocytes. The metabolic changes caused by portal diversion have apparently created a more favourable equilibrium between the synthesis and excretion of the abnormal alpha-1-antitrypsin.

Child, Preschool↗
PubMed1983

The Eck fistula in animals and humans.

In all species so far studied, including man, portacaval shunt causes the same changes in liver morphology, including hepatocyte atrophy, fatty infiltration, deglycogenation, depletion and disorganization of the rough endoplasmic reticulum (RER) and its lining polyribosomes, and variable but less specific damage to other organelles. Many, perhaps all, biosynthetic processes are quickly depressed, largely secondary to the selective damage to the RER, which is the "factory" of the cell. These structural and metabolic changes in the liver after portal diversion are caused by the diversion around the liver of the hepatotrophic substances in portal venous blood, of which endogenous insulin is the most important. In experimental animals, the injury of Eck's fistula can be prevented by infusing insulin into the tied-off hilar portal vein. The subtle but far-reaching changes in hepatic function after portal diversion have made it possible to use this procedure in palliating three inborn errors of metabolism: glycogen storage disease, familial hypercholesterolemia, and alpha 1-antitrypsin deficiency. In these three diseases, the abnormalities caused by portal diversion have counteracted abnormalities in the patients that were caused by the inborn errors. In these diseases, amelioration of the inborn errors depends on the completeness of the portal diversion. In contrast, total portal diversion to treat complications of portal hypertension is undesirable and always will degrade hepatic function if a significant amount of hepatopetal portal venous blood is taken from the liver. When total portal diversion is achieved (and this is to be expected after all conventional shunts), the incidence of hepatic failure and hepatic encephalopathy is increased. If portal diversion must be done for the control of variceal hemorrhage, a selective procedure such as the Warren procedure is theoretically superior to the completely diverting shunt. In practice, better patient survival has not been achieved after selective shunts than after conventional shunts, but the incidence of hepatic encephalopathy has been less.

Animals↗
PubMed1983

Portacaval shunt in patients with familial hypercholesterolemia.

Portacaval shunt was performed in ten patients with homozygous and two with heterozygous familial hypercholesterolemia (FH). Total serum cholesterol was lowered by 20% to 55.4% during follow-up periods of 14 months to almost 9 years, with commensurate decreases in LDL cholesterol. The effect on HDL cholesterol and triglyceride levels was variable. Tendinocutaneous xanthomas diminished or disappeared. Growth and development in children proceeded or accelerated. There was no detectable emotional or intellectual deterioration. Hepatic failure did not occur, although blood ammonia concentrations and serum alkaline phosphatase levels increased relative to preoperative values. Cardiac symptoms were often improved, but evidence of reversal of cardiovascular lesions was inconclusive. Three patients with pre-existing heart disease died of cardiac complications after 4 months, 18 1/2 months, and 30 months. Portacaval shunt has been effective therapy for patients with FH who were refractory or intolerant to medical treatment; it should be performed before the development of irreversible cardiovascular damage.

Adolescent↗
PubMed1981

Cyclosporin A and steroid therapy in sixty-six cadaver kidney recipients.

From nine to 18 months ago, 66 patients were given 67 randomly matched cadaveric kidneys with cyclosporin A and steroid therapy. Nine of the recipients were undergoing retransplantation. The over-all kidney survival rate to date has been 77.6 per cent, and 78.8 per cent of the recipients are dialysis-free. The patient mortality in this learning phase was 13.3 per cent. Nephrotoxicity, hepatotoxicity and other side-effects of cyclosporin A could usually be dealt with by dosage adjustments, making feasible the chronic use of this agent. One B-cell immunoblastic sarcoma was encountered which was monoclonal. It was not responsible for death. Another patient had a perforation of the intestine from a lympho-proliferative reaction in which the B cells were polyclonal. After jejunal resection a year ago, there were no further complications. This lesion was not classified as a lymphoma. Both lympho-proliferative lesions were associated with a rise in antibody to viral capsid antigen of Epstein-Barr virus. Results of this study have verified the effectiveness and relative safety of cyclosporin A with steroids for immunosuppression in human recipients of cadaveric kidneys.

Adolescent↗
PubMed1981

Acute interstitial nephritis complicating Legionnaires' Disease.

An acute interstitial nephritis was found in a patient with sudden renal failure and lung infection caused by Legionella pneumophilia. Our patient regained and maintained normal renal function after a short period of dialysis support. The diagnosis should be considered in any patient with a chest infection complicated by acute renal failure especially if confusion is disproportionate to the degree of uremia.

Acute Disease↗
PubMed1980

Significance of haematuria in hypertensive patients.

Of 409 patients attending a clinic for control of hypertension, 74 (18%) were found to have haematuria, and all those with haematuria had significant renal impairment. The association of raised serum IgA levels and HLA BW35 in these patients suggests that some have the adult form of the IgA/C3 disease described in children.

Adult↗
PubMed1980

Decline in survival after liver transplantation.

Twenty-three recent cases of orthotopic liver transplantation were individually reviewed in an effort to determine why survival had declined from the 50% one-year survival rate of an immediately precedent series. In the series of 23, only six (26%) achieved one-year survival. Faulty case selection, technical complications, the use of damaged organs, and complications of immunosuppression were the main causes of death. Attention was directed to the possible use of preoperative lymphoid depletion to improve the effectiveness and safety of immunosuppression.

Adolescent↗
PubMed1980

Renal isotransplantation without immunosuppression.

Four renal isografts have been performed and all have had satisfactory function for 7 1/2 to 17 2/3 years without prophylactic or therapeutic immunosuppression. Three of these patients originally had glomerulonephritis, and in one there was histologic evidence of recurrent disease, 7 1/2 years after transplantation, without proteinura and without change in renal function. Although this experience is small, it suggests that prophylactic immunosuppression is not appropriate for recipients of renal isografts.

Diseases in Twins↗
PubMed1980

The use of cyclosporin A and prednisone in cadaver kidney transplantation.

Eighteen patients were treated with primary cadaveric renal transplantation using cyclosporin A therapy, and four more patients undersent cadaveric retransplantation. Eleven of the 22 recipients were conditioned with lymphoid depletion before transplantation, using thoracic duct drainage or lymphapheresis for two to eight and one-half weeks. Cyclosporin A was begun a few hours before grafting. The other 11 patients were pretreated with cyclosporin A for from one day to 18 days. After transplantation, the majority of patients in both subgroups of 11 had rejection develop, but in most, the immunologic process was readily controlled with relatively small dosages of prednisone. After follow-up periods of two to four and one-half months, one patient has died of the complications of a coronary artery reconstruction that was not related to the transplantation. Another graft was lost from rejection, and a third organ was removed because of ureteral necrosis. Nineteen of the original 22 cadaveric kidneys are functioning, including 17 of the 18 kidneys given to patients who were undergoing transplantation for the first time. The only loss in the latter group of 18 patients was in the patient who died after an open heart operation. Results of these studies have shown that cyclosporin A is a superior and safe immunosuppressive drug but that, for optimal use in cadaveric transplantation, it usually should not be given alone. Steroid therapy greatly amplified the value of cyclosporin A. Unless major delayed morbidity develops which is not obvious so far, this drug combination should permit revolutionary advances in the transplantation of all organs. Other adjuncts to the cyclosporin A-steroid combination, including lymphoid depletion techniques, will require further investigation.

Adult↗
PubMed1980

Stimulation of hepatic regeneration after partial hepatectomy by infusion of a cytosol extract from regenerating dog liver.

A cytosol liver extract was prepared from adult dog livers and from liver remnants that had been regenerating for one, two and three days after 72 per cent partial hepatectomy. Given intraportally, the most active of these cytosols did not stimulate proliferation in the livers of normal dogs. However, infused during a six hour period into the portal vein of test group dogs, the cytosol from 48 and, especially, 72 hour regenerating livers augmented the regeneration response ordinarily produced by 44 per cent partial depatectomy. The effect was delayed. It became identifiable 48 hours after infusion and rached a peak at 72 hours. Neither augmentation nor significant inhibition of the normal regeneration response was produced by cytosol from normal liver and 24 hour regenerating liver or by six hour infusion of insulin. The amplification effect of active cytosol was equivocal when the infusions were given intraperitoneally and was not demonstrable at all by the intravenous route. In these investigations, it is confirmed that there are growth control factors in regenerating liver but the nature or physiologic significance of the factor or factors has not been clarified.

Animals↗
PubMed1979

Growth-stimulating factor in regenerating canine liver.

Extracts from dog livers which had been regenerating for 24, 48, and 72 h after hepatectomy were infused for 6 h into the left portal vein of animals which had fresh portacaval shunts (Eck fistula) and which were killed 2 and 3 days later. The brief exposure to the 48-h and especially the 72-h regenerating liver extracts induced a delayed proliferative response predominantly in the left liver lobes, with a slight spillover effect to the right liver lobes but none to the kidney. The response reached its peak 3 days later. In the left but not the right liver lobes, both the 48-h and the 72-h regenerating liver extract reversed the atrophy ordinarily caused by Eck fistula in 3 days and partly prevented the ultrastructural hepatocyte deterioration characteristic of Eck fistula. The active liver extracts apparently contained a growth-control factor or factors which is (are) not insulin or glucagon.

Animals↗