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Biomedical subjects

B L Shneider

Publications and source records attributed to B L Shneider.

At least 19 recordsLinked to original sources
PubMed2006

Favorable long-term outcome after liver-kidney transplant for recurrent hemolytic uremic syndrome associated with a factor H mutation.

A male child initially presented with atypical hemolytic uremic syndrome (HUS) at the age of 4 months and progressed within weeks to end stage renal disease (ESRD). At the age of 2 years he received a live-related kidney transplant from his mother, which, despite initial good function, was lost to recurrent disease after 2 weeks. Complement factor H analysis showed low serum levels and the presence of two mutations on different alleles (c.2918G > A, Cys973Tyr and c.3590T > C, Val1197Ala). His survival on dialysis was at risk because of access failure and recurrent bacteremic episodes. Therefore, at the age of 5 years he received a combined liver-kidney transplant with pre-operative plasma exchange. Initial function of both grafts was excellent and this has been maintained for over 2 years. This report suggests that despite setbacks in previous experience, combined liver-kidney transplantation offers the prospect of a favorable long-term outcome for patients with HUS associated with complement factor H mutations.

Child, Preschool↗
PubMed2006

CMV-IVIG for prevention of Epstein Barr virus disease and posttransplant lymphoproliferative disease in pediatric liver transplant recipients.

A randomized controlled trial of CMV-IVIG (cytomegalovirus-intravenous immunoglobulin) for prevention of Epstein Barr virus (EBV) posttransplant lymphoproliferative disease (PTLD) in pediatric liver transplantation (PLTx) recipients was begun in Pittsburgh and subsequently expanded to four additional sites. Protocol EB viral loads were obtained in a blinded fashion; additional loads could be obtained for clinical indications. Patients were followed for 2 years post-LTx. Eighty-two evaluable patients (39 CMV-IVIG, 43 placebo) developed 18 episodes of EBV disease (7 CMV-IVIG, 11 placebo) including nine cases of PTLD (three CMV-IVIG, six placebo). No significant differences were seen in the adjusted 2-year EBV disease-free rate (CMV-IVIG 79%, placebo 71%) and PTLD-free rate (CMV-IVIG 91%, placebo 84%) between treatment and placebo groups at 2 years (p > 0.20). The absence of significant effect of CMV-IVIG may be explained by a lack of efficacy of the drug or limitations of sample size.

Adolescent↗
PubMed2003

Physicochemical and physiological properties of 5alpha-cyprinol sulfate, the toxic bile salt of cyprinid fish.

5alpha-Cyprinol sulfate was isolated from bile of the Asiatic carp, Cyprinus carpio. 5alpha-Cyprinol sulfate was surface active and formed micelles; its critical micellization concentration (CMC) in 0.15 M Na+ using the maximum bubble pressure device was 1.5 mM; by dye solubilization, its CMC was approximately 4 mM. At concentrations >1 mM, 5alpha-cyprinol sulfate solubilized monooleylglycerol efficiently (2.1 molecules per mol micellar bile salt). When infused intravenously into the anesthetized rat, 5alpha-cyprinol sulfate was hemolytic, cholestatic, and toxic. In the isolated rat liver, it underwent little biotransformation and was poorly transported (Tmax congruent with 0.5 micromol/min/kg) as compared with taurocholate. 5alpha-Cyprinol, its bile alcohol moiety, was oxidized to its corresponding C27 bile acid and to allocholic acid (the latter was then conjugated with taurine); these metabolites were efficiently transported. 5alpha-Cyprinol sulfate inhibited taurocholate uptake in COS-7 cells transfected with rat asbt, the apical bile salt transporter of the ileal enterocyte. 5alpha-Cyprinol had limited aqueous solubility (0.3 mM) and was poorly absorbed from the perfused rat jejunum or ileum. Sampling of carp intestinal content indicated that 5alpha-cyprinol sulfate was present at micellar concentrations, and that it did not undergo hydrolysis during intestinal transit. These studies indicate that 5alpha-cyprinol sulfate is an excellent digestive detergent and suggest that a micellar phase is present during digestion in cyprinid fish.

Animals↗
PubMed2001

Hepatocyte nuclear factor-1alpha is an essential regulator of bile acid and plasma cholesterol metabolism.

Maturity-onset diabetes of the young type 3 (MODY3) is caused by haploinsufficiency of hepatocyte nuclear factor-1alpha (encoded by TCF1). Tcf1-/- mice have type 2 diabetes, dwarfism, renal Fanconi syndrome, hepatic dysfunction and hypercholestrolemia. Here we explore the molecular basis for the hypercholesterolemia using oligonucleotide microchip expression analysis. We demonstrate that Tcf1-/- mice have a defect in bile acid transport, increased bile acid and liver cholesterol synthesis, and impaired HDL metabolism. Tcf1-/- liver has decreased expression of the basolateral membrane bile acid transporters Slc10a1, Slc21a3 and Slc21a5, leading to impaired portal bile acid uptake and elevated plasma bile acid concentrations. In intestine and kidneys, Tcf1-/- mice lack expression of the ileal bile acid transporter (Slc10a2), resulting in increased fecal and urinary bile acid excretion. The Tcf1 protein (also known as HNF-1alpha) also regulates transcription of the gene (Nr1h4) encoding the farnesoid X receptor-1 (Fxr-1), thereby leading to reduced expression of small heterodimer partner-1 (Shp-1) and repression of Cyp7a1, the rate-limiting enzyme in the classic bile acid biosynthesis pathway. In addition, hepatocyte bile acid storage protein is absent from Tcf1-/- mice. Increased plasma cholesterol of Tcf1-/- mice resides predominantly in large, buoyant, high-density lipoprotein (HDL) particles. This is most likely due to reduced activity of the HDL-catabolic enzyme hepatic lipase (Lipc) and increased expression of HDL-cholesterol esterifying enzyme lecithin:cholesterol acyl transferase (Lcat). Our studies demonstrate that Tcf1, in addition to being an important regulator of insulin secretion, is an essential transcriptional regulator of bile acid and HDL-cholesterol metabolism.

Animals↗
PubMed2001

One hundred nine living donor liver transplants in adults and children: a single-center experience.

OBJECTIVE: To summarize the evolution of a living donor liver transplant program and the authors' experience with 109 cases. SUMMARY BACKGROUND DATA: The authors' institution began to offer living donor liver transplants to children in 1993 and to adults in 1998. METHODS: Donors were healthy, ages 18 to 60 years, related or unrelated, and ABO-compatible (except in one case). Donor evaluation was thorough. Liver biopsy was performed for abnormal lipid profiles or a history of significant alcohol use, a body mass index more than 28, or suspected steatosis. Imaging studies included angiography, computed tomography, endoscopic retrograde cholangiopancreatography, and magnetic resonance imaging. Recipient evaluation and management were the same as for cadaveric transplant. RESULTS: After ABO screening, 136 potential donors were evaluated for 113 recipients; 23 donors withdrew for medical or personal reasons. Four donor surgeries were aborted; 109 transplants were performed. Fifty children (18 years or younger) received 47 left lateral segments and 3 left lobes; 59 adults received 50 right lobes and 9 left lobes. The average donor hospital stay was 6 days. Two donors each required one unit of banked blood. Right lobe donors had three bile leaks from the cut surface of the liver; all resolved. Another right lobe donor had prolonged hyperbilirubinemia. Three donors had small bowel obstructions; two required operation. All donors are alive and well. The most common indications for transplant were biliary atresia in children (56%) and hepatitis C in adults (40%); 35.6% of adults had hepatocellular carcinoma. Biliary reconstructions in all children and 44 adults were with a Roux-en-Y hepaticojejunostomy; 15 adults had duct-to-duct anastomoses. The incidence of major vascular complications was 12% in children and 11.8% in adult recipients. Children had three bile leaks (6%) and six (12%) biliary strictures. Adult patients had 14 (23.7%) bile leaks and 4 (6.8%) biliary strictures. Patient and graft survival rates were 87.6% and 81%, respectively, at 1 year and 75.1% and 69.6% at 5 years. In children, patient and graft survival rates were 89.9% and 85.8%, respectively, at 1 year and 80.9% and 78% at 5 years. In adults, patient and graft survival rates were 85.6% and 77%, respectively, at 1 year. CONCLUSION: Living donor liver transplantation has become an important option for our patients and has dramatically changed our approach to patients with liver failure. The donor surgery is safe and can be done with minimal complications. We expect that living donor liver transplants will represent more than 50% of our transplants within 3 years.

ABO Blood-Group System↗
PubMed2001

Intestinal bile acid transport: biology, physiology, and pathophysiology.

Intestinal reabsorption of bile salts plays a crucial role in human health and disease. This process is primarily localized to the terminal ileum and is mediated by a 48-kd sodium-dependent bile acid cotransporter (SLC10A2 = ASBT). ASBT is also expressed in renal tubule cells, cholangiocytes, and the gallbladder. Exon skipping leads to a truncated version of ASBT, which sorts to the basolateral surface and mediates efflux of bile salts. Inherited mutation of ASBT leads to congenital diarrhea secondary to bile acid malabsorption. Partial inhibition of ASBT may be useful in the treatment of hypercholesterolemia and intrahepatic cholestasis. During normal development in the rat ileum, ASBT undergoes a biphasic pattern of expression with a prenatal onset, postnatal repression, and reinduction at the time of weaning. The bile acid responsiveness of the ASBT gene is not clear and may be dependent on both the experimental model used and the species being investigated. Future studies of the transcriptional and posttranscriptional regulation of the ASBT gene and analysis of ASBT knockout mice will provide further insight into the biology, physiology, and pathophysiology of intestinal bile acid transport.

Animals↗
PubMed2001

The role of quantitative Epstein-Barr virus polymerase chain reaction and preemptive immunosuppression reduction in pediatric liver transplantation: a preliminary experience.

BACKGROUND: Risk factors for the development of posttransplant lymphoproliferative disease (PTLD), a major cause of morbidity and mortality after pediatric liver transplantation, are primary Epstein-Barr virus (EBV) infection and intensity of immunosuppression. The authors assessed monitoring of EBV replication and preemptive immunosuppression reduction in pediatric liver transplant recipients. METHODS: The authors prospectively followed monthly EBV-quantitative competitive polymerase chain reaction to measure EBV replication in 23 patients who underwent liver transplant between July 1997 and November 1998. Preemptive immunosuppression reduction was instituted for significant EBV replication. Patients were followed up for at least 1 year and divided in two groups for analysis (group 1, pretransplant seronegative for EBV [13 patients]; group 2, seropositive for EBV [10 patients]). RESULTS: In group 1, 9 of 13 patients had positive polymerase chain reaction results at a mean time of 22.4 weeks after transplantation. All but one of these patients were asymptomatic. In seven of nine patients, preemptive immunosuppression reduction was undertaken without development of PTLD or rejection. In two of nine patients, immunosuppression could not be continuously reduced, and both patients experienced low-grade and medically responsive PTLD. In no patient in group 2 did an EBV-positive viral load or PTLD develop. CONCLUSIONS: Prospective longitudinal measurement of EBV by quantitative competitive polymerase chain reaction permits early detection of asymptomatic viral replication. Subsequent preemptive reduction of immunosuppression may prevent the progression to PTLD.

Adolescent↗
PubMed2001

Cholecystectomy prevents expansion of the bile acid pool and inhibition of cholesterol 7alpha-hydroxylase in rabbits fed cholesterol.

To study the effect of cholecystectomy on the regulation of classic and alternative bile acid syntheses, gallbladder-intact (n = 20) and cholecystectomized (n = 20) New Zealand White rabbits were fed either chow or chow with 2% cholesterol (3 g/day). After 10 days, bile fistulas were constructed in half of each rabbit group to recover and measure the bile acid pool and biliary bile acid flux. After cholesterol feeding, the bile acid pool size increased from 268 +/- 55 to 444 +/- 77 mg (P < 0.01) with a 2-fold rise in the biliary bile acid flux in intact rabbits but did not expand the bile acid pool (270 +/- 77 vs. 276 +/- 62 mg), nor did the biliary bile acid flux increase in cholecystectomized rabbits. Ileal apical sodium-dependent bile acid transporter protein increased 46% from 93 +/- 6 to 136 +/- 23 units/mg (P < 0.01) in the intact rabbits but did not change in cholecystectomized rabbits (104 +/- 14 vs. 99 +/- 19 units/mg) after cholesterol feeding. Cholesterol 7alpha-hydroxylase activity was inhibited 59% (P < 0.001) while cholesterol 27-hydroxylase activity rose 83% (P < 0.05) after cholesterol feeding in the intact rabbits but neither enzyme activity changed significantly in cholesterol-fed cholecystectomized rabbits. Fecal bile acid outputs reflecting bile acid synthesis increased significantly in the intact but not in the cholecystectomized rabbits fed cholesterol. Removal of the gallbladder prevented expansion of the bile acid pool after cholesterol feeding as seen in intact rabbits because ileal bile acid transport did not increase. As a result, cholesterol 7alpha-hydroxylase was not inhibited.

Animals↗
PubMed2001

The role of magnetic resonance cholangiography in the management of children and young adults after liver transplantation.

We reviewed the results of 50 magnetic resonance (MR) cholangiograms to evaluate their usefulness in directing clinical management in young patients after liver transplantation (LTx). Thirty-two patients underwent 50 MR cholangiograms on a 1.5-T unit. Studies were performed from 1 week to 16 yr after LTx. Indications included biochemical abnormalities with (n = 19) or without (n = 16) biopsy evidence for chronic rejection, sepsis (n = 14), and intractable ascites (n = 1). Original interpretations were compared to laboratory and ultrasound findings, and clinical outcome. Of 19 studies performed on 14 patients with biopsy evidence of chronic rejection, 16 were abnormal on MR (but only one was abnormal on ultrasound), resulting in corrective surgery (n = 1), re-Tx (n = 1), and endoscopic dilatation (n = 1). Of 16 studies on 16 patients with biochemical abnormalities without evidence of chronic rejection on biopsy, 14 were abnormal on MR (but only five of 13 on ultrasound), leading to corrective surgery (n = 3) and re-listing for Tx (n = 3). Thirteen of 14 studies on six patients with sepsis were abnormal on MR (five of nine were abnormal on ultrasound), identifying surgically correctable strictures (n = 2), and leading to re-Tx (n = 1) and percutaneous biliary drainage procedures (n = 2). The one patient with ascites had a normal study. We advocate usage of MR cholangiography for the detection of biliary complications after LTx, particularly in those patients who present with biochemical abnormalities that are not easily explained by acute cellular rejection or viral infection and in those with biliary sepsis.

Adolescent↗
PubMed2000

Non-adherence in pediatric liver transplant recipients--an assessment of risk factors and natural history.

Despite the fact that non-adherence to medical therapy is one of the major causes of late morbidity and mortality in pediatric liver transplant recipients, little is known of the risk factors involved in this behavior. Three cases of fatal non-adherence are reported. Factors associated with non-adherence were investigated by performing a retrospective chart review of a panel of 27 variables in an age-matched cohort of 15 pediatric liver transplant recipients. The most striking differences between the severely non-adherent group and the age-matched cohort included history of substance abuse, child abuse (physical or sexual), not having two parents at home, having received public assistance, having been diagnosed with a psychiatric disorder, and history of school dropout. In addition it appeared that a pretransplant diagnosis of autoimmune hepatitis was associated with more significant medical sequelae related to non-adherence. These findings are preliminary owing to the retrospective design of this study, but could be used as a starting point for a prospective study of this important phenomenon.

Adolescent↗
PubMed2000

A pilot study of posttraumatic stress and nonadherence in pediatric liver transplant recipients.

BACKGROUND: Symptoms of posttraumatic stress disorder (PTSD) were described in survivors of life-threatening diseases, the trauma being the experiences associated with the disease or its treatment. Their prevalence in liver transplant recipients is unknown. Based on clinical observations, we hypothesize that a significant proportion of pediatric liver transplant recipients suffers from PTSD symptoms. We further hypothesize that nonadherence (noncompliance) to medical management may, in some cases, be associated with these symptoms. Traumatized patients, according to this hypothesis, will avoid taking their medications, because these serve as painful reminders of the disease. OBJECTIVES: To determine the prevalence of PTSD symptoms in a sample of pediatric liver transplant recipients. To determine whether symptoms of PTSD are associated with nonadherence in these patients. To describe the clinical presentation of PTSD and the management of severe nonadherence in patients who suffer from this disorder. METHODS: Nineteen pediatric liver transplant recipients and their caretakers were interviewed, using the UCLA Post Traumatic Stress Disorder Reaction Index (PTSRI). Data were obtained on a few demographic parameters and perception of disease threat. Adherence was evaluated by 2 methods: 1) a clinician panel (taking into account the clinical sequelae of severe nonadherence); and 2) computation of the standard deviations (SDs) of consecutive determinations of blood levels of Tacrolimus (a higher SD means higher variability between individual measures and is therefore an indicator of nonadherence). As an illustration of the general phenomenon, we describe 3 cases of liver transplant recipients who were nonadherent and who suffered from PTSD. RESULTS: Six of 19 patients had positive scores on all 3 components of the PTSRI (PTSD patients). Three of these, and none of the others, were considered significantly nonadherent by the panel. Therefore, nonadherence was significantly associated with the existence of symptoms from all 3 domains of PTSD (Fisher's exact test) in our sample. In particular, a high avoidance score on the PTSRI was highly correlated with panel-determined nonadherence. Further, SD of medication levels were significantly higher in PTSD patients, compared with the rest of our sample. No significant differences were found in perception of disease threat or demographic variables between PTSD patients and the rest of our sample. The 3 cases that we describe became adherent to their medications when symptoms of PTSD subsided during the course of therapy. CONCLUSIONS: Clinically significant nonadherence, determined by 2 different methods, was associated with the full spectrum of PTSD symptoms in this sample. It was especially associated with a high avoidance score, which suggests that avoidance of reminders of the disease (eg, medications) may be a mechanism of nonadherence. Screening for and management of these symptoms, therefore, may improve adherence. This novel concept may be applicable to other patient populations. However, more data are needed before any definite conclusions can be drawn.

Adolescent↗
PubMed2000

Ileal bile acid transport regulates bile acid pool, synthesis, and plasma cholesterol levels differently in cholesterol-fed rats and rabbits.

We investigated the effect of ileal bile acid transport on the regulation of classic and alternative bile acid synthesis in cholesterol-fed rats and rabbits. Bile acid pool sizes, fecal bile acid outputs (synthesis rates), and the activities of cholesterol 7alpha-hydroxylase (classic bile acid synthesis) and cholesterol 27-hydroxylase (alternative bile acid synthesis) were related to ileal bile acid transporter expression (ileal apical sodium-dependent bile acid transporter, ASBT). Plasma cholesterol levels rose 2.1-times in rats (98 +/- 19 mg/dl) and 31-times (986 +/- 188 mg/dl) in rabbits. The bile acid pool size remained constant (55 +/- 17 mg vs. 61 +/- 18 mg) in rats but doubled (254 +/- 46 to 533 +/- 53 mg) in rabbits. ASBT protein expression did not change in rats but rose 31% (P < 0.05) in rabbits. Fecal bile acid outputs that reflected bile acid synthesis increased 2- and 2.4-times (P < 0.05) in cholesterol-fed rats and rabbits, respectively. Cholesterol 7alpha-hydroxylase activity rose 33% (24 +/- 2.4 vs. 18 +/- 1.6 pmol/mg/min, P < 0.01) and mRNA levels increased 50% (P < 0.01) in rats but decreased 68% and 79%, respectively, in cholesterol-fed rabbits. Cholesterol 27-hydroxylase activity remained unchanged in rats but rose 62% (P < 0.05) in rabbits. Classic bile acid synthesis (cholesterol 7alpha-hydroxylase) was inhibited in rabbits because an enlarged bile acid pool developed from enhanced ileal bile acid transport. In contrast, in rats, cholesterol 7alpha-hydroxylase was stimulated but the bile acid pool did not enlarge because ASBT did not change. Therefore, although bile acid synthesis was increased via different pathways in rats and rabbits, enhanced ileal bile acid transport was critical for enlarging the bile acid pool size that exerted feedback regulation on cholesterol 7alpha-hydroxylase in rabbits.

Animals↗
PubMed1999

Prospective longitudinal analysis of quantitative Epstein-Barr virus polymerase chain reaction in pediatric liver transplant recipients.

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) remains a significant cause of morbidity and mortality in pediatric liver transplant recipients. Epstein-Barr Virus (EBV) mismatch associated with more prevalent use of split-liver, reduced size, and living-related transplants has increased the risk of primary EBV infection and subsequent PTLD. Early identification of EBV viremia may reduce the risk of PTLD, because it allows for early adjustment of immunosuppression and antiviral therapy. METHODS: EBV viral load was measured monthly by quantitative competitive polymerase chain reactions in three pediatric liver transplant recipients. RESULTS: Onset of EBV viremia was documented in one recipient. Established EBV viremia was followed in the other two recipients (one with chronic rejection and one with PTLD) who were initially tested once monitoring was initiated in our program. CONCLUSIONS: EBV quantitative competitive polymerase chain reactions may represent a promising way to follow EBV viral load and potentially prevent the development of PTLD.

Epstein-Barr Virus Infections↗