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Biomedical subjects

R Williams

Publications and source records attributed to R Williams.

At least 325 records · Page 18Linked to original sources
PubMed1997

Treatment of experimental ischemia/reperfusion injury with S-adenyosylmethionine: evidence that donor pretreatment complements other regimens.

Triple therapy with S-adenosylmethionine (SAM) (given to the donor animal, included in University of Wisconsin solution [UW], and added to the reperfusing medium) has been shown to reduce the sequential cold and warm ischemia/reperfusion injuries characteristic of the liver transplantation procedure. To clarify the actions of SAM during different stages of ischemia/ reperfusion, we have compared its benefit in five dosage regimens, using perfused rat livers after sequential periods of 24 hr cold and 20 min rewarming ischemia. When added only to UW, the presence of SAM throughout ischemia improved hepatic blood flow by 26% after 15 min of reperfusion versus no treatment (2.32+/-0.18 vs. 1.84+/-0.11 ml/min/g liver, P<0.05). SAM also improved blood flow by 23% during the 3-hr perfusion overall (P<0.05). Oxygen consumption and the release of purine nucleoside phosphorylase (PNP) were decreased (both P<0.05). When added to both UW and the perfusate, SAM additionally increased bile production at 15 min (7.14+/-1.21 vs. 2.31+/-0.74 mg/h/g liver, P<0.01). By pretreating the liver donor with SAM in vivo, and including it in the preservation and reperfusing media, it was possible to prolong and amplify the benefits on blood flow (P<0.001) and bile production (P<0.05) and to sustain glucose uptake (P<0.01). An acute exposure to SAM, when used in saline to flush UW from the graft before reperfusion, increased blood flow at 15 min (by 68%) and over a 3-hr period (both P<0.001), but no indices of metabolic activity were improved. Oxygen consumption and PNP release were both decreased (P<0.05). When added to the perfusate (present throughout reperfusion), SAM increased blood flow at 15 min (58%) and over a 3-hr period (P<0.01 in both cases). Net glucose uptake was increased (P<0.05), whereas oxygen consumption (P<0.001) and PNP release fell (P<0.05). Actions of SAM achieved acutely and over the intermediate- and long-term all seem to underlie its benefits in reducing ischemia/reperfusion injuries.

Adenosine↗
PubMed1997

Differentiation of core gene products of the hepatitis B virus in infected liver tissue using monoclonal antibodies.

Hepatitis B virus (HBV) core gene translational products were localised previously in the cytoplasm and/or in the nuclei of infected cells. We investigated in naturally infected human hepatocytes whether this variation in the subcellular expression is due to differences in the presence of assembled core particles and other core gene derived proteins, the expression of HBeAg and the processing of liver tissue. By immunostaining of liver specimens infected with HBeAg-positive and HBeAg-minus variants of HBV, using monoclonal antibodies specific for assembled core particles and for various epitopes on denatured core protein, it was shown that virtually all immunoreactive core gene products are assembled into core particles. The latter are present both in the nuclei and in the cytoplasm of hepatocytes, independent of the infecting virus strain. A marked reduction or absence of immunoreactivity, observed with some monoclonal antibodies, was shown to result from nucleotide sequence variations within or close to the corresponding epitope. These results demonstrate that immunoreactive products, derived from the HBV core gene, in the nuclei and cytoplasm of human hepatocytes represent assembled core particles and that monoclonal antibodies with known recognition sites can reveal region-specific core gene variation of the infecting HBV population.

Amino Acid Sequence↗
PubMed1997

Lead exposure in ironworkers.

In adults, lead toxicity is most commonly caused by occupation in a lead industry. Whereas lead toxicity has been described in workers who are involved in bridge rehabilitation, as of this date there has been no systematic evaluation published regarding the conditions responsible for lead toxicity in ironworkers. This is a report of a study designed to identify risk factors for elevated blood-lead levels in ironworkers. One hundred fifty members of a 2,400-member local ironworkers union volunteered to have their blood drawn for lead and zinc protoporphyrin analysis and to complete a questionnaire regarding demographics, health, and occupation. The relationships between these variables and blood-lead level were analyzed using student's t-test, chi-square, and logistic regression. Current work on a lead job, rivet busting as the predominant job task, and cigarette smoking were all found to be significantly associated with elevated blood-lead level. Whereas cigarette smoking and current work with lead have been previously identified as risk factors for toxicity, interventions to prevent lead toxicity in ironworkers should also focus on work practices during rivet busting.

Adult↗
PubMed1997

Mechanisms of drug-induced lupus. III. Sex-specific differences in T cell homing may explain increased disease severity in female mice.

OBJECTIVE: To determine if sex-specific differences in lymphocyte trafficking could contribute to increased disease severity in female mice. METHODS: A lupus-like disease was induced by injecting male and female mice with procainamide-treated T cell clones. Trafficking was examined by labeling the injected cells with 51Cr or 5-chloromethylfluorescein diacetate. RESULTS: Females developed more autoimmune liver disease and greater titers of anti-DNA antibodies than did males, and 2-7 times more cells accumulated in the female spleens. Splenectomy prevented the development of autoantibodies and renal and liver disease. Oophorectomy decreased the splenic homing, autoantibody titer, and liver disease severity, to levels found in males. CONCLUSION: T cells traffic differently to the spleen in male and female mice, and the spleen appears to be essential in the disease process. This suggests that differences in T cell homing could contribute to sex-specific disease severity in this murine model, and also possibly in human disease.

Adoptive Transfer↗
PubMed1997

Proteome analysis of Saccharomyces cerevisiae: a methodological outline.

Proteome analysis offers a unique means of identifying important proteins, characterizing their modifications and beginning to describe their function. This is achieved through the combination of two technologies: protein separation and selection by two-dimensional gel electrophoresis, and protein identification and characterization by mass spectrometry. This methodological outline sketches the strengths and weaknesses of the two central technologies used, and provides both practical tips and the theoretical background for their utilization. One application of these technologies is illustrated by the characterization of genes, revealed by sequencing, but which have no--or only weak homology--to any other known genes. Other applications, for example the identification of protein markers for particular human diseases, are only referred to. The aim of the article is thus to provide the basis for a sound understanding of the full potential and limitations of proteome analysis.

Databases, Factual↗
PubMed1997

Graft and systemic disease in long-term survivors of liver transplantation.

In this clinicopathological study, we have examined the prevalence of biochemical and histological graft abnormalities in 116 patients who have lived for longer than five years since orthotopic liver transplantation (mean, 8.4 years [range, 5.2-19.5 years]). In each patient, the protocol biopsy was carried out in addition to full clinical, biochemical, and immunological evaluation. The renal function was preserved in most patients (mean creatinine, 86 micromol/L [0.95 mg%]) with only 35% showing any degree of impairment, and only one patient with pretransplant renal failure required dialysis. Forty one (35%) of the patients had normal biochemical liver function tests (LFTs); 19 of these patients had histologic abnormalities. Of the remaining 75 patients with abnormal LFTs, 65 were found to have histological abnormalities on liver biopsy. Some of the 84 patients with an abnormal histology had more than one finding but were placed into 6 categories according to the main change as follows: chronic hepatitis in 27; primary biliary cirrhosis-like changes in 8; cholangitis in 15; structural anomalies in 26; chronic rejection in 2; mild acute cellular rejection in 1; and miscellaneous in 5. The recurrence of B, C, or autoimmune hepatitis accounted for 14 cases of chronic hepatitis, whereas, in 13 cases, no cause could be detected. The latter cases included 8 patients who had liver transplants for primary biliary cirrhosis (PBC), leaving suboptimally treated rejection or disease recurrence as possible causes. Characteristic histological features of PBC were observed in 8 additional cases that had liver transplantations for this disease. Of the 26 cases with structural anomalies, various types of occlusive vasculopathy were detected during pre- or posttransplantation in 12 cases. All but one of these were maintained on azathioprine, the only possible etiological factor in the 14 other cases, 5 of whom showed stabilization or clinical and histological improvement following withdrawal of the drug. De-novo malignancy was seen in 3.4% of cases, causing mortality in only one patient to date. This study demonstrates an unexpectedly high prevalence of histological abnormalities that is found often in the presence of normal biochemical liver-function in liver grafts of long-term survivors. Although graft loss at this time is rare, protocol liver biopsies at 5 years, and thereafter at 2-year intervals, may allow for earlier beneficial therapeutic intervention.

Adolescent↗
PubMed1997

Regional cerebral edema and chloride space in galactosamine-induced liver failure in rats.

The pathogenesis of cerebral edema, which is a major complication of fulminant hepatic failure, is poorly understood. In previous studies, increased regional brain water content was observed in rats at an early stage of acute liver failure caused by galactosamine. At a later stage when the animals had developed deep coma, brain water content was reduced, possibly as a result of generalized dehydration. In the present investigation, we have determined brain water content at a late stage of liver failure, 48 hours after galactosamine, in animals that had been maintained in fluid balance by continuous intraperitoneal infusion of glucose solution. In these animals, brain water content, determined from the ratio of wet to dry weight, showed a greater increase than that observed previously at the early stage (hindbrain region [cerebellum, pons, and brain stem] increased by 4.2%; forebrain region increased by 1.4% compared with controls). Regional analysis of brain water, using a tissue-specific gravity method, showed a significant increase in cerebellar gray matter water content. Analysis of chloride space showed the extra fluid to be mainly extracellular in the hindbrain region, but not in the forebrain region. Ultrastructural examination of capillaries in gray matter from cerebellum and cerebrum showed no evidence of gross disruption of the tight junctions. Swelling of the astroglial foot processes was observed in the cerebellar gray matter. These results suggest that both vasogenic and cytotoxic mechanisms of edema formation occur in the brain during liver failure.

Acute Disease↗
PubMed1997

Associations between alleles of the major histocompatibility complex and type 1 autoimmune hepatitis.

Susceptibility for type 1 autoimmune hepatitis has been associated with the major histocompatibility alleles DRB1*0301, DRB3*0101, DRB1*0401, and DRB4*0103, whereas the DRB1*1501 allele may protect from the disease. Our aim was to determine if these alleles or others influence clinical manifestations and prognosis. Eighty-six white patients were evaluated prospectively for immune features and outcomes. Class I alleles were determined by microlymphocytotoxicity, and class II alleles were assessed by polymerase chain reaction with sequence-specific oligonucleotide probes or sequence-specific primers. One hundred two white, normal subjects were typed in the same fashion. Patients with concurrent immunologic diseases were more commonly positive for DRB4*0103 than patients without these features (68% vs. 38%, P = .01). DRB1*0301 (86% vs. 45%, P = .008) and the DRB1*0301-DRB3*0101 haplotype (79% vs. 42%, P = .02) occurred more commonly in patients who deteriorated during corticosteroid therapy. In contrast, DRB1*0401 and the DRB1*0401-DRB4*0103 haplotype were associated with a lower frequency of death from liver failure or the need for transplantation than patients with other alleles (0% vs. 37%, P = .03). Patients with DRB1*0301 differed from those with DRB1*0401 in that they were younger and failed treatment more commonly (27% vs. 5%, P = .04). We conclude that alleles associated with susceptibility to type 1 autoimmune hepatitis also influence its clinical features and prognosis. DRB4*0103 is associated with concurrent immune diseases, DRB1*0301 with a poor treatment response, and DRB1*0401 with a lower frequency of hepatic death or transplantation.

Adolescent↗
PubMed1997

HLA-C genes and susceptibility to type 1 autoimmune hepatitis.

Susceptibility to autoimmune hepatitis (AIH) is associated with the HLA A1-B8-DR3 haplotype, DR4 antigen, and, more specifically, the HLA DRB3*0101, DRB1*0301, and DRB1*0401 alleles. Few investigators, however, have examined the HLA C locus in AIH, which warrants detailed study in view of its recently described roles in immunoregulation. Eighty-seven adult, white patients with well-characterized type 1 AIH and 100 controls were studied. HLA C and HLA DRB1 alleles were assigned by polymerase chain reaction (PCR)-based genotyping. HLA A and B antigens were determined by standard microlymphocytotoxicity assay. Extended haplotypes were constructed according to known patterns of linkage disequilibrium. Only one HLA C locus allele, Cw*0701, which was present in 54% of patients versus 34% of controls (P = .006; relative risk [RR] = 1.54) was associated with AIH. The overall increase in the frequency of the Cw*07 gene (70.1% of patients vs. 54% of controls; P = .024; RR = 1.3) was due entirely to inheritance of the Cw*0701 allele rather than the other Cw*07 alleles, Cw*0702, *0703, and *0704. The RR for Cw*0701 (RR = 1.54) is greater than that for HLA A1 (RR = 1.33) and DRB1*0301 (RR = 1.49), but less than that for HLA-B8 (RR = 1.75). The present findings suggest that the gene or genes conferring susceptibility to AIH lie in the region centromeric to the HLA A locus between HLA C and DRB1. Although linkage disequilibrium with both B8 and DRB1*0301 may account for our finding of an increased frequency of Cw*0701, it is also possible that this allele contributes to disease susceptibility, perhaps by interaction with natural killer cells or cytotoxic T lymphocytes.

Adult↗
PubMed1997

Maternal and perinatal outcome in severe pregnancy-related liver disease.

Acute fatty liver of pregnancy (AFLP) and the syndrome of hemolysis, elevated liver enzyme levels, and low platelet count (HELLP) are rare but major disorders of the third trimester of pregnancy. Over a 10-year period, 46 women (median age, 30 years; range, 17-41 years) developed hepatic dysfunction severe enough to require transfer to our Liver Failure Unit. Three quarters of the women were nulliparous, and 5 had twin pregnancies; the median gestational age was 35 weeks (range, 24-40 weeks). At admission, 32 patients (70%) were preeclamptic and 21 (46%) were encephalopathic and/or ventilated. Thirty-two patients (70%) had clinical features and laboratory values consistent with AFLP, and 7 (15%) had HELLP syndrome. One patient had preeclamptic liver rupture requiring liver transplantation. In 6 other patients, causes of severe liver dysfunction unrelated to pregnancy were found. Infectious complications occurred in 17 of the patients with AFLP (53%) and in 2 of those with HELLP syndrome (29%). Major intra-abdominal bleeding occurred in 12 women (10 with AFLP), 9 of whom required laparotomies for clot evacuation. Four patients with AFLP (12.5%) had a fatal outcome, with a corresponding perinatal mortality rate of 9%. There were no maternal or perinatal deaths associated with HELLP syndrome. In contrast to results of many previous studies, the results of this large series suggest a relatively favorable maternal and perinatal outcome in severe AFLP and HELLP syndrome. Further improvements in outcome are likely to be achieved through the prevention of the bleeding and infectious complications associated with these disorders.

Adolescent↗
PubMed1997

Urinary tract infections in primary biliary cirrhosis and other chronic liver diseases.

In a study to determine the prevalence of urinary tract infections (UTI) in primary biliary cirrhosis, midstream specimens of urine from 97 females with primary biliary cirrhosis and 85 females with other chronic liver diseases were investigated prospectively for urinary pathogens and Mycobacterium gordonae. No significant differences between primary biliary cirrhosis and the two groups were observed in the prevalence of significant bacteriuria (11.3% vs. 7.1%), the prevalence of Escherichia coli UTI (9.3% vs. 7.1%) or the colony morphology of Escherichia coli. No mycobacterial species were grown from any sample. In both groups, the prevalence of UTI was higher in patients with cirrhosis (20% in both) than in those without.

Adult↗
PubMed1997

Incidence of childhood diabetes mellitus in Yorkshire, northern England, is associated with nitrate in drinking water: an ecological analysis.

The relationship between the incidence of childhood-onset insulin-dependent diabetes mellitus and levels of nitrate in drinking water in the former Yorkshire Regional Health Authority was investigated by means of an ecological analysis. A population-based register contributed 1797 0-16-year-olds diagnosed with diabetes between 1978 and 1994. Nitrate data were based on 9330 samples of drinking water tested between 1990 and 1995 in 148 water supply zones, for which 1991 census small area statistics were taken on population density, ethnicity and socio-economic status. Diabetes incidence was positively associated with raised mean nitrate levels with a standardised incidence ratio of 115 in zones with greater than 14.85 mg.1-1 (chi2 = 26.81, 1 df, p < 0.001). Significant negative trends were found between standardised incidence ratios and proportion of non-whites in the population (chi2 = 33.57, 1 df, p < 0.001), childhood population density (chi2 = 30.81, 1 df, p < 0.001) and the Townsend deprivation score (chi2 = 33.89, 1 df, p < 0.001). Poisson regression modelling, adjusting for the other factors, showed a significant increase in relative incidence rate ratio from a baseline of 1 at nitrate levels below 3.22 mg.1-1 to 1.27 (95% confidence interval 1.09, 1.48) for mean nitrate levels above 14.85 mg.1-1. An association between higher nitrate levels in domestic drinking water and incidence of childhood diabetes has been demonstrated. This was not explained by the ethnic composition of the population, population density or socioeconomic status. Nitrate in drinking water may be a precursor of chemicals which are toxic to the pancreas.

Adolescent↗
PubMed1997

Tacrolimus-based immunosuppression after liver transplantation: a randomised study comparing dual versus triple low-dose oral regimens.

To evaluate the efficacy and safety of oral tacrolimus-based immunosuppressive induction therapy, 130 primary orthotopic liver transplant (OLT) recipients were randomised to treatment in an open, parallel-group, European multicentre trial. Following OLT, patients were immediately administered either tacrolimus (0.10 mg/kg) and prednisolone (dual therapy group) or tacrolimus (0.06 mg/kg) in conjunction with prednisolone and azathioprine (triple therapy group) both orally. Patient survival at 1 year was 79.4% for the dual therapy group and 88.7% for the triple therapy group (P = 0.194); 1-year graft survival rates were 76.5% in the dual therapy group and 80.6% in the group receiving triple therapy (P = 0.615). The frequencies of rejection (dual therapy 42.6%, triple therapy 50.0%; P = 0.482), infection, and other complications (renal, neurological and glucose metabolic disorders) were similar in both groups. Tacrolimus whole blood trough concentrations were detectable on days 1 and 2, respectively, in the dual and triple therapy treatment groups whilst median tacrolimus blood concentrations in the triple therapy group reached levels similar to those in the dual therapy group on postoperative day 11 following a steady increase in dose. After 1 year, 54.4% of the patients randomised to dual therapy were receiving tacrolimus monotherapy and only 56.4% of the patients randomised to triple therapy continued to receive azathioprine. In conclusion, oral tacrolimus-based immunosuppression is both potent and safe when administered as induction therapy after OLT. Treatment may commence at either 0.06 or 0.10 mg/ kg per day, but doses may need to be increased to the latter value within the first 10 days to maintain effective immunosuppression.

Administration, Oral↗