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Biomedical subjects

A S Klein

Publications and source records attributed to A S Klein.

At least 37 records · Page 2Linked to original sources
PubMed1996

Functional activity of anti-C6 antibodies elicited in C6-deficient rats reconstituted by liver allografts. Ability to inhibit hyperacute rejection of discordant cardiac xenografts.

A critical role of the complement membrane attack complex (C5b-9) in mediating hyperacute rejection has been demonstrated previously in fully C6-deficient PVG (C-)(RT1c) rats that reject guinea pig cardiac xenografts at a delayed tempo (45 +/- 9 hr; n=16) compared with C6-sufficient PVG (C+)(RT1c) hosts (0.5 +/- 2 hr; n=6). We have investigated whether selective depletion of C6 from Lewis rats by antibody therapy prevents hyperacute rejection. A polyclonal rat-antirat C6 antibody was induced in PVG (C-) recipients by orthotopic liver transplants from congenic PVG (C+) donors. These liver grafts produced high levels of C6 that reconstituted the complement function of PVG (C-) hosts by 7 days, but the recipients responded within 28 days with the synthesis of an IgG1 antibody to rat C6. The antiserum inhibited hemolytic complement activity of Lewis (RT1(1)) rats in vivo and in vitro. The effect of C6 depletion on Xg survival was investigated by injecting Lewis rats with 2 ml of rat-antirat C6 antiserum before and 1 ml after reperfusion of the guinea pig cardiac xenograft. Lewis rats rejected guinea pig cardiac xenografts after treatment with this rat-antirat C6 antiserum in 38 +/ -11 hr (n=3). Treatment with normal control sera from PVG (C-) rats did not prolong guinea pig cardiac xenograft survival in the Lewis rats (1 +/- 0.7 hr; n=3)(P<0.0043). Injection of 3 ml of the IgG fraction purified from the rat-antirat C6 antibody (33 mg/ml) prolonged xenograft survival to 13.6 +/- 4 hr (n=4) compared with the survival of 0.61 +/- 0.3 hr (n=4) after injection of control rat IgG (33 mg/ml) (P<0.005). These results demonstrate that specific depletion of C6 by antibody therapy has a significant effect on guinea pig cardiac xenograft survival in the Lewis rat. These findings further suggest that C6 depletion may be beneficial to patients undergoing hyperacute rejection of xenografts or allografts.

Animals↗
PubMed1996

Allopurinol: discrimination of antioxidant from enzyme inhibitory activities.

This study was designed to quantitatively discriminate the specific xanthine oxidase (XO) inhibitory from the relatively nonspecific antioxidant activities of allopurinol, both in vitro and in vivo in the rat. XO activity, determined by the spectrophotometric assay for urate generation over time, was completely inhibited in vitro by allopurinol at concentrations > or = 200 microM. Allopurinol's antioxidant activity was determined in vitro using a linolenic acid peroxidation (LAP) assay. Although the known antioxidant butylated hydroxytoluene effectively inhibited LAP (80% inhibition of malondialdehyde generation at 10(1) microM), allopurinol (10(1)-10(3) microM) did not inhibit this LAP (p < .01). Rat serum obtained after oral administration of allopurinol (100 mg/kg x 2 doses) did not suppress LAP in vitro more than did control rat serum. Following oral administration of allopurinol (2-50 mg/kg x 2 doses), dose-dependent inhibition of XO activity was observed in the homogenates of the liver (to 5% of control level; p < .001) and the intestine (to 12% of control level; p < .001). We conclude that while 2-50 mg/kg of oral allopurinol effectively suppresses XO activity in the rat liver and intestine, antioxidant activity is not seen even in doses up to 100 mg/kg. The selective enzymatic inhibitory effect of allopurinol at these doses therefore should provide a useful tool to allow the discrimination of the effects of xanthine oxidase in particular from the effects of reactive oxygen metabolites in general.

Allopurinol↗
PubMed1996

Prostaglandin E1 administration following orthotopic liver transplantation: a randomized prospective multicenter trial.

BACKGROUND & AIMS: Prostaglandin E1 (PGE1) has been used after orthotopic liver transplantation (OLT) based on limited clinical data suggesting PGE1 infusion improves immediate hepatic allograft function. The aim of this study was to conduct a randomized double-blinded multicenter trial to evaluate the effect of PGE1 on early hepatic and renal function in patients undergoing OLT. METHODS: One hundred eighteen patients were randomized to receive either PGE1 or crystalloid placebo intravenously after allograft revascularization. Primary end points were incidence of primary allograft nonfunction (PNF) or severe renal dysfunction. RESULTS: The incidence of PNF was 6.7% (4 of 60) and 6.9% (4 of 58) in the control and PGE1 groups, respectively. PGE1 infusion was, however, associated with improved early renal function (mean peak creatinine level of 1.4 +/- 1.0 and 2.0 +/- 1.0 in patients treated with PGE1 and placebo, respectively; P < 0.001). Severe renal dysfunction occurred more frequently in the placebo group (26.7%) than in the PGE1 group (13.8%; P = 0.65). Additionally, dialysis treatments were more frequent in the placebo group (0.7 +/- 2.0 per patient) than in the PGE1 group (0.2 +/- 1.0 per patient; P = 0.10). Initial intensive care unit stay was shorter in patients treated with PGE1 (4.0 +/- 3.6 days) compared with controls (10.5 +/- 17.1 days) (P < 0.01). CONCLUSIONS: PGE1 administration after OLT resulted in improved renal function and decreased initial postoperative intensive care unit stay but did not affect the incidence of PNF.

Adult↗
PubMed1996

Liver transplantation in infants younger than 1 year of age.

OBJECTIVE: The authors report on experience with liver transplantation for infants younger than 1 year of age. SUMMARY BACKGROUND DATA: Over the last 15 years, orthotopic liver transplant has become the only lifesaving procedure available for infants with end-stage liver disease. Many transplant centers initially required infants to reach a specific weight or age to minimize morbidity and mortality. Size-appropriate infant donors also were uncommon. As a result, many children, in the first few years of life, died of their disease. The availability of reduced-size cadaveric and living-related liver transplants has offered the ability to transplant the young infant with liver failure. METHODS: The authors instituted a program to aggressively transplant infants with liver failure in the first year of life using both cadaveric and living-related liver donors. RESULTS: Between June 1991 and January 1995, 13 infants were transplanted for rapidly progressive liver failure. Infant age ranged from 4 to 11 months (mean, 7.5 months). The cause of liver failure included biliary atresia (11), alpha 1-antitrypsin deficiency (1), and liver failure secondary to echovirus 7 (1). The United Network for Organ Sharing status at the time of transplant ranged from status 4, intensive care unit bound (4 patients); status 3, hospitalized (4 patients); or status 2, failing at home (5 patients). Six patients (46%) received cadaveric whole organ (2) or segmental transplants (4). Seven patients (54%) received left lateral segment living-related transplants from parental donors. After operation, patients received cyclosporine or FK506-based immunosuppression. Three patients (23%) required four retransplants (two cadaveric for primary nonfunction; one living-related for graft thrombosis in the face of fungal infection and bile leak). Postoperative complications included primary nonfunction (15%), rejection (85%), graft vascular thrombosis (15%, two of three revascularized successfully), bacterial and fungal infections (77%), and viral infections (46%). Epstein-Barr virus-associated lymphoproliferative developed in two patients (15%). Intestinal perforation requiring reoperation developed in two patients (15%). Bile leaks requiring reoperation or transhepatic stinting or both developed in three patients (23%). Two patients died in the perioperative period (< 1 month) from a combination of primary nonfunction or graft thrombosis and sepsis. Overall survival was 85%, ranging from 11.0 months to 4.5 years. CONCLUSIONS: Orthotopic liver transplantation in infants younger than 1 year of age poses significant challenges from technical and infectious complications. Despite these barriers, overall patient survival is comparable to that of older children and adults.

Biliary Atresia↗
PubMed1996

Hepatic reticuloendothelial system dysfunction after intestinal ischemia-reperfusion.

The functional capacity of the hepatic reticuloendothelial system (RES) was studied under conditions of intestinal shock. Wistar rats underwent intestinal ischemia (60 min)-reperfusion or a sham procedure. One-half of each group received intravenous infusion of 2.6 x 10(-6) g/kg lipopolysaccharide B. Phagocytic clearance and phagocytic killing by the hepatic RES were quantitated using a double label bacteria clearance assay. Hepatic phagocytosis was unchanged 3 h after reperfusion of the ischemic intestine but hepatic killing was significantly decreased compared with the sham situation. The results were not different in animals who had received LPS B infusion. The plasma endotoxin levels correlated inversely to the hepatic killing efficiency (r = -.801) in the shocked animals given exogenous endotoxin. The decreased capacity of the hepatic RES to degrade bacteria present in the portal circulation could be an important pathophysiologic mechanism in the development of bacterial translocation.

Animals↗
PubMed1996

Effect of hemorrhagic shock and resuscitation upon hepatic phagocytic clearance and killing of circulating microorganisms.

We evaluated the effects of hemorrhagic shock/resuscitation (S/R) on hepatic reticuloendothelial system function, using an in vivo assay that discriminantly quantitates its two essential components, phagocytic clearance and phagocytic killing of double-labeled Escherichia coli injected intravenously. Rats were subjected to hemorrhagic shock at mean arterial pressure at 50 +/- 5 torr for 2 h, resuscitated, and survived. Hepatic phagocytic clearance was significantly decreased immediately following and 6 h after S/R, compared with sham-shocked rats, but recovered to normal levels after 24 h. Although hepatic killing efficiency was increased initially, and transiently depressed 6 h later, it was strikingly upregulated after 24 h. As a consequence, net hepatic killing was transiently suppressed at 0 and 6 h, but upregulated after 24 h. Pre-treatment with proinflammatory agonists, including endotoxin, IFN-gamma, or IFN-gamma + TNF-alpha enhanced both hepatic killing efficiency and net hepatic killing. These observations suggest that although hepatic killing function is initially impaired after the onset of S/R, it is strikingly upregulated 24 h later, simulating both the initial immunosuppression, and the later hyperinflammatory response to systemic S/R that could lead to multiple organ dysfunction syndrome.

Animals↗
PubMed1996

Role of reactive oxygen metabolites in murine peritoneal macrophage phagocytosis and phagocytic killing.

This study was designed to quantify the role of reactive oxygen metabolites (ROMs) in two distinct components of murine peritoneal macrophage activity, phagocytosis and killing, and to discriminate quantitatively the degree to which each component is dependent on NADPH oxidase and/or xanthine oxidase. A fluorochromatic vital staining technique was modified to simultaneously quantify phagocytosis and microbicidal activity of macrophages incubated with Candida parapsilosis targets. To determine the role of ROMs, macrophages were preincubated with free radical scavengers [superoxide dismutase (SOD) and/or catalase] or with selective inhibitors of xanthine oxidase (XO, e.g., allopurinol) or NADPH oxidase [diphenyleneiodonium (DPI)]. Phagocytosis was not affected by treatment of macrophages with SOD, catalase, allopurinol, or DPI. Candidacidal activity, however, was inhibited by SOD, allopurinol, or DPI. The inhibitory effects of DPI and allopurinol were additive. Histochemical and biochemical assays demonstrated substantial quantities of XO in murine peritoneal macrophages. The findings suggest that the generation of ROMs by XO- and NADPH oxidase-dependent pathways are each important for phagocytic killing by murine peritoneal macrophages.

Allopurinol↗
PubMed1996

Kupffer cell depletion by gadolinium chloride enhances liver regeneration after partial hepatectomy in rats.

Although previous work suggests that tumor necrosis factor-alpha (TNF) promotes liver regeneration after partial hepatectomy (PH), the source of TNF is unknown. If Kupffer cells release TNF after PH, then Kupffer cell depletion by gadolinium chloride (GdCl) should inhibit liver regeneration. To test this hypothesis, cytokine expression and regenerative events were compared in GdCl-treated and control rats. Functional assays and Northern blot analysis of a Kupffer cell-specific mRNA confirmed that GdCl depleted Kupffer cells. Despite this, semiquantitative reverse transcription-polymerase chain reaction analysis of total hepatic RNA showed six- to eightfold higher levels of TNF transcripts in GdCl-treated rats. In this group, PH caused 12-to 16-fold greater induction of interleukin-6, a TNF-inducible cytokine, and two- to threefold greater induction of several cytokine-regulated genes (c-jun, C/EBP-beta, and C/EBP-delta). GdCl also amplified regeneration-associated increases in the DNA binding activity of AP-1, a growth regulatory transcription factor. Furthermore, hepatic incorporation of [3H]thymidine, expression of the S-phase antigen, proliferating cell nuclear antigen, and the hepatocyte mitotic index were each significantly greater in GdCl-treated rats. Thus, although GdCl causes Kupffer cell depletion, it does not decrease liver TNF and actually enhances liver regeneration after PH.

Animals↗
PubMed1995

Extrahepatic synthesis of C6 in the rat is sufficient for complement-mediated hyperacute rejection of a guinea pig cardiac xenograft.

The liver is the major source of complement (C) components, but extrahepatic sources of C, such as macrophages and endothelial cells, have been hypothesized to contribute to inflammation. Our experiments demonstrate that extrahepatically produced C6 can contribute to hyperacute rejection. PVG (RT1c) rats with normal C activity (PVG (C+)) reject guinea pig cardiac xenografts in 0.5 +/- 0.2 hr, but fully C6-deficient PVG (RT1c) rats (PVG (C-)) reject guinea pig cardiac xenografts in 45 +/- 9 hr. PVG (C+) rats, which received liver transplants from PVG (C-) rats and retained all extrahepatic sources of C6, rejected guinea pig cardiac xenografts in 0.6 +/- 0.03 hr (n = 3). PVG (C-) rats, which received bone marrow transplants from PVG (C+) rats, had C6 levels restored to 10% of that of the donor and rejected guinea pig cardiac xenografts in 9 +/- 3.2 hr (n = 5). Thus, extrahepatic sources of C6 can contribute to xenograft rejection.

Animals↗
PubMed1995

FK506 (tacrolimus) compared with cyclosporine for primary immunosuppression after pediatric liver transplantation. Results from the U.S. Multicenter Trial.

We report on the efficacy and safety of FK506 (tacrolimus) compared with a cyclosporine (CsA)-based immunosuppressive regimen after 1 year of treatment in pediatric liver allograft recipients (< 12 years) participating in a multicenter U.S. randomized trial. Patients received either FK506 or CsA as primary immunosuppression following a first ABO-compatible liver transplant. Intravenous FK506 was initiated at 0.1 mg/kg per day, followed by oral FK506 beginning at 0.3 mg/kg per day. The dose was adjusted to maintain plasma trough levels of 0.5-2.0 ng/ml. The CsA group was treated according to each center's usual protocol. Both groups received the same initial doses of corticosteroids. All rejection episodes were biopsy-proven and a standardized algorithm was adopted for the treatment of rejection. Thirty patients were randomized to the FK506 group and 20 to the CsA group. After twelve months of follow-up 20 patients remained in the FK506 group and 13 in the CsA group. Patient survivals were 80% and graft survival 70% in the FK506 group compared with 81% and 71% respectively, in the CsA group. 48% of the FK506 group remained rejection-free compared with 21% of the CsA group, and 79% of FK506-treated patients did not require OKT3 compared with 68% of CsA treated patients. The cumulative corticosteroid dose was less at each time point throughout the first year in the FK506 group. The incidence of serious and minor infections was similar in both groups. Nephrotoxicity, neurotoxicity, and gastrointestinal disturbances were the major toxicities reported. Differences did not reach statistical significance between the two groups although major neurologic events, diarrhea and dyspepsia were more often reported in the FK506 group. There was no difference in mean serum creatinine at 12 months between the two groups. There was a tendency toward lower mean serum cholesterol in the FK506 group. There was no hirsuitism in the FK506 group compared with a 30% incidence in the CsA group. In conclusion, compared with CsA, there is a trend toward less rejection in FK506-treated pediatric allograft recipients, while both drugs have a similar spectrum of side effects.

Adrenal Cortex Hormones↗
PubMed1994

Hepatic and extrahepatic biosynthesis of complement factor C6 in the rat.

The relative contributions of liver and bone marrow (BM) constituents to systemic C6 production were compared in a rat model. Liver grafts were transplanted from C6-sufficient PVG (RT1c) rats (PVG (C+)) to profoundly C6-deficient PVG rats (PVG (C-)). C6 levels were restored to 32% within 24 h and reached more than 80% of that of the PVG (C+) donor within 7 days post-grafting, which indicates that the liver is a primary source of systemic C6 production. When livers were transplanted from PVG (C-) to PVG (C+) rats (n = 3), levels of C6 dropped to 42% of pretransplant levels within 24 h and remained between 30 and 40% for more than 100 days after grafting. To determine the source of extrahepatic C6 production, BM was transplanted from PVG (C+) to PVG (C-) rats after total body irradiation. Levels of C6 increased from undetectable levels to 5% of C6 levels of the donor PVG (C+) rat within 60 days. Replenishing PVG (C-) recipients with BM after treatment of recipients with busulfan, which preferentially allows reconstitution with donor myelomonocyte stem cells, resulted in restoration of C activity. Treatment with cyclophosphamide before BM transplantation, which preferentially allows reconstitution of lymphoid stem cells, did not restore hemolytic C activity in PVG (C-) rats. These results were confirmed directly by the successful restoration of C activity with BM depleted of lymphocytes by counterflow centrifugal elutriation from PVG (C+) rats. These in vivo experiments demonstrate that the liver is a primary, but not the sole, source of C6 in the rat and that extrahepatic sources, such as myelomonocytes, and not lymphoid cells in the BM produce a significant amount of systemic C6 in the rat.

Animals↗
PubMed1994

Phylogenetic inferences on the relationship of North American and European Picea species based on nuclear ribosomal 18S sequences and the internal transcribed spacer 1 region.

We have used PCR (polymerase chain reaction) to isolate nuclear ribosomal sequences from seven species of Picea (spruce). The amplified products contained approximately 200 base pairs from the 3' end of the 18S rRNA gene and the entire first internal transcribed spacer (ITS1). The sequences from these two functionally distinct regions were aligned and variable positions were used to construct a character matrix for cladistic-based phylogenetic analysis. Short insertions or deletions (indels) were common in the ITS1 and distinguished some intragenus phylogenetic relationships. In the present study, evolutionary relationships, based on DNA sequence variation within the ribosomal repeat, were determined for seven North American and European species of Picea. The results support the hypothesis of Wright (1955) that P. rubens and P. mariana are more closely related to the European species P. omorika than to other North American Picea. Molecular data suggest P. pungens has a closer relationship to eastern North American and European Picea than its presumed affiliation with northwestern American species.

Base Sequence↗
PubMed1994

Evidence for free radical-mediated lipid peroxidation at reperfusion of human orthotopic liver transplants.

BACKGROUND: Generation of toxic oxygen metabolites at reperfusion may contribute to the injury sustained as a consequence of harvest and ischemic preservation of organ allografts. Because there is a paucity of evidence that this mechanism is operative in human beings, we measured the generation of ethane into the exhaled breath as a biomarker of free radical-mediated lipid peroxidation in human liver transplantation. METHODS: A novel technique that increased the previous standard of sensitivity 100-fold was used to measure picomole quantities of ethane in exhaled breath of eight recipients undergoing human orthotopic liver transplantation. RESULTS: Ethane production correlated closely with the specific events of liver transplantation including the initial reperfusion of the allografts. In every case a twofold to threefold increase in ethane production was superimposed on a stable baseline immediately after reestablishment of portal vein blood flow through the donor liver. CONCLUSIONS: Ethane production was interpreted as evidence of hepatic lipid peroxidation, presumably mediated by toxic metabolites of oxygen occurring at reperfusion. This noninvasive approach allowed localization of the time point at which lipid peroxidation occurred and may facilitate quantification of lipid peroxidation mediated by free radicals and other toxic oxygen metabolites during operation.

Adult↗
PubMed1993

Corticosteroids improve survival of children with AIDS and Pneumocystis carinii pneumonia.

OBJECTIVE: To determine if corticosteroids administered in addition to antimicrobials improve survival in children with acquired immunodeficiency syndrome and severe Pneumocystis carinii pneumonia (PCP). DESIGN: Before-after, nonrandomized, case-comparison study. SETTING: Pediatric intensive care unit of a tertiary care teaching hospital in Florida. PARTICIPANTS: Eleven children infected with the human immunodeficiency virus (HIV) with confirmed PCP. SELECTION PROCEDURE: Infants with HIV infection and acute respiratory failure due to PCP were studied sequentially. INTERVENTION: The first seven infants were treated with antimicrobials alone while the next four received a 2-week course of methylprednisolone sodium succinate in addition to antimicrobials. MEASUREMENTS AND RESULTS: The two groups were similar with respect to age, route of HIV infection, stage of HIV disease, CD4 T-cell count, antiretroviral therapy, and respiratory parameters at intubation. All children treated with antimicrobials alone died while receiving mechanical ventilation. Survival of the children who received corticosteroid therapy was significantly improved (P < .05), and all were weaned from the ventilator. CONCLUSIONS: Corticosteroids administered in addition to antimicrobials and supportive care improve the short-term survival of HIV-infected children who have acute respiratory failure due to PCP.

AIDS-Related Opportunistic Infections↗
PubMed1992

Breath ethane: a specific indicator of free-radical-mediated lipid peroxidation following reperfusion of the ischemic liver.

A major component of the organ injury mediated by toxic oxidants, such as seen following reperfusion of the ischemic liver, is due to the peroxidation of polyunsaturated fatty acids, especially of cell membranes. We utilized the measurement of exhaled breath ethane, a metabolic product unique to oxidant-mediated lipid peroxidation, as a noninvasive indicator of this process in swine liver subjected to warm ischemia/reperfusion. Under rigorously controlled anesthesia conditions, pig livers were subjected to 2 h of warm total ischemia, followed by reperfusion in situ. Expired air was collected and its ethane content quantitated by a novel gas chromatographic technique. The time course of breath ethane generation correlated closely with the appearance of hepatocellular injury as measured by impairment of Factor VII generation and other measures of liver integrity. Moreover, the administration of the specific superoxide free radical scavenger, superoxide dismutase (SOD), significantly attenuated both the elaboration of ethane and the hepatocellular injury. These findings not only provide confirmation of the previously reported link between hepatocellular injury by free radicals generated at reperfusion, but also establish the use of expired breath ethane analysis as a sensitive, specific, and noninvasive indicator of the injury process in real time.

Alanine Transaminase↗