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Biomedical subjects

Roger Williams

Publications and source records attributed to Roger Williams.

At least 55 records · Page 3Linked to original sources
PubMed2004

Systemic inflammatory response exacerbates the neuropsychological effects of induced hyperammonemia in cirrhosis.

BACKGROUND/AIMS: Studies in acute liver failure show correlation between evidence of a systemic inflammatory response syndrome (SIRS) and progression of hepatic encephalopathy (HE). We tested the hypothesis that SIRS mediators, such as nitric oxide and proinflammatory cytokines, may exacerbate the neuropsychological effects of hyperammonemia in cirrhosis. METHODS: Ten patients with cirrhosis were studied, 24-36 h after admission with clinical evidence of infection, and following its resolution. Hyperammonemia was induced by oral administration of an amino-acid (aa) solution mimicking hemoglobin composition. Inflammatory mediators, nitrate/nitrite, ammonia, aa profiles and a battery of neuropsychological tests were measured. RESULTS: The hyperammonemia generated in response to the aa solution was similar prior to, and after resolution, of the inflammation (P=0.77). With treatment of the infection there were significant reductions in white blood cell count (WBC), C-reactive protein (CRP), nitrate/nitrite, interleukin-6, interleukin-1beta and tumour necrosis factor alpha. Induced hyperammonemia resulted in significant worsening of the neuropsychological scores when patients showed evidence of SIRS but not after its resolution. CONCLUSIONS: The significant deterioration of neuropsychological test scores following induced hyperammonemia during the inflammatory state, but not after its resolution, suggests that the inflammation and its mediators may be important in modulating the cerebral effect of ammonia in liver disease.

Amino Acids↗
PubMed2004

Diagnostic value of Doppler assessment of the hepatic and portal vessels and ultrasound of the spleen in liver disease.

OBJECTIVES: To investigate the clinical utility and the intra-observer and inter-observer variability of Doppler ultrasound assessment of the hepatic and portal vessels along with measurement of spleen size in the diagnosis of chronic liver disease and cirrhosis. METHODS AND MATERIALS: Ultrasound measurements of portal vein diameter (PVD), portal vein velocity (PVV), hepatic arterial resistance index (HARI), hepatic vein profile (HVP), and spleen size were obtained in 49 controls and 45 patients with liver disease (23 with primary biliary cirrhosis, 22 with hepatitis C) by two experienced observers, who each performed three blinded measurements of each variable. Control values were derived from normal hospital workers. Percutaneous liver biopsies in 41 of the patients showed cirrhosis (14 patients), moderate/severe fibrosis (13 patients), and early disease (14 patients). RESULTS: Seventy-one percent of cirrhotic patients had splenomegaly (> 13.6 cm). The spleen size was significantly larger in cirrhotics (16.0 cm) than in non-cirrhotics (13.0 cm, P < 0.009) and healthy controls (10.7 cm, P < 0.00005), and was the only independent predictor of cirrhosis, with a threshold of 15 cm predicting cirrhosis with a specificity of 98%, positive predictive value of 93%, sensitivity of 57% and negative predictive value of 80%. HVP was abnormal in 76.9% of cirrhotics, 57.7% of non-cirrhotics and 2.1% of controls (P < 0.04). However, the mean PVV, PVD and HARI were no different between controls and patients or between cirrhotic and non-cirrhotic liver disease. There was significant inter-observer variability for PVV, but intra-observer and inter-observer variability was acceptable for the other measurements. CONCLUSIONS: Splenomegaly size and abnormal HVP are useful predictors of chronic liver disease and cirrhosis, and both can be measured reliably and reproducibly. However, Doppler measurements of PVV, PVD and HARI are not useful in distinguishing patients with chronic liver disease from normal controls.

Adult↗
PubMed2004

Single nucleotide polymorphisms in the interferon-gamma and interleukin-10 genes do not influence chronic hepatitis C severity or T-cell reactivity to hepatitis C virus.

BACKGROUND: The mechanisms by which interferon-gamma (IFN-gamma) contributes to inter-individual heterogeneity in the severity of chronic hepatitis C (CH-C) are unknown. In 116 consecutive patients with CH-C, we tested the hypothesis that host genetic factors regulating IFN-gamma production and activity influence the severity of liver damage and hepatitis C virus (HCV)-specific T-cell reactivity. METHODS: We determined the genotypes of functionally significant polymorphisms in the IFN-gamma gene and in the promoter of interleukin-10 (IL-10), a cytokine that counteracts IFN-gamma. We also measured concanavalin A (Con A)-stimulated IL-10 and IFN-gamma production, and the frequency of virus-specific T-cells, producing IFN-gamma or IL-10. RESULTS: The grade of inflammation and the stage of fibrosis of CH-C showed no associations with either the IFN-gamma or IL-10 promoter polymorphisms or with Con A-stimulated IL-10 or IFN-gamma production. Similarly, there were no associations between HCV-specific T-cell frequencies and these host genetic factors. On multivariate analysis, the grade of inflammation and the duration of HCV infection accounted for only 37% of the variance in the stage of CH-C (P<0.0001). This percentage did not increase by including any genetic variables in the analyses. CONCLUSION: Future studies investigating the entire cytokine gene sequences will provide better information regarding genetic variations responsible for inter-individual differences in the severity of CH-C.

Adolescent↗
PubMed2004

Longitudinal analysis of CD8+ T cells specific for structural and nonstructural hepatitis B virus proteins in patients with chronic hepatitis B: implications for immunotherapy.

The cytotoxic T-cell response in chronic hepatitis B virus (HBV) infection has been described as weak and mono- or oligospecific in comparison to the more robust virus-specific T-cell response present in resolved infection. However, chronic hepatitis B is a heterogeneous disease with markedly variable levels of virus replication and liver disease activity. Here we analyzed (both directly ex vivo and after in vitro stimulation) the HBV-specific CD8 T-cell responses against structural and nonstructural HBV proteins longitudinally in patients with different patterns of chronic infections. We found that the profiles of virus-specific CD8(+)-T-cell responses during chronic infections are highly heterogeneous and influenced more by the level of HBV replication than by the activity of liver disease. An HBV DNA load of <10(7) copies/ml appears to be the threshold below which circulating multispecific HBV-specific CD8(+) T cells are consistently detected. Furthermore, CD8(+) T cells with different specificities are differentially regulated during chronic infections. HBV core-specific CD8(+) T cells are associated with viral control, while CD8(+) T cells specific for envelope and polymerase epitopes can occasionally be found in the setting of high levels (>10(7) copies) of HBV replication. These findings have implications for the design of immunotherapy for chronic HBV infections.

Adult↗
PubMed2003

Semantic memory deficit with a left thalamic infarct.

Previous studies of patients with thalamic lesions have reported consistent word finding difficulties without a proposed etiology. The authors describe a patient with a focal left thalamic infarct, pronounced word finding problems, and a relatively selective impairment in semantic memory for object recall from features. The thalamus is proposed to facilitate electrical activity between brain regions that encode object features, resulting in object recall. Thalamic dysfunction disrupting object recall is a plausible etiology for impaired word finding in some patients.

Brain Infarction↗
PubMed2003

Cytochrome P4502D6(193-212): a new immunodominant epitope and target of virus/self cross-reactivity in liver kidney microsomal autoantibody type 1-positive liver disease.

Cytochrome P4502D6 (CYP2D6), target of liver kidney microsomal autoantibody type 1 (LKM1), characterizes autoimmune hepatitis type 2 (AIH2) but is also found in patients with chronic hepatitis C virus (HCV) infection. To provide a complete linear epitope B cell map of CYP2D6, we tested peptides spanning the entire sequence of CYP2D6. In addition to confirming previously described antigenic sites, we identified four new epitopes (193-212, 238-257, 268-287, and 478-497). CYP2D6(193-212) is immunodominant and was the target of 12 of 13 (93%) patients with AIH2 and 5 of 10 (50%) HCV/LKM1-positive patients. Because LKM1 is present in both AIH2 and a viral infection, we tested whether Abs to CYP2D6(193-212) arise through cross-reactive immunity between virus and self. We identified a hexameric sequence "RLLDLA" sharing 5 of 6 aa with "RLLDLS" of HCV(2985-2990) and all 6 aa with CMV(130-135). Of 17 CYP2D6(193-212)-reactive sera, 11 (7 AIH and 4 HCV) reacted by ELISA with the HCV homologue, 8 (5 AIH and 3 HCV) with the CMV homologue, and 8 (5 AIH and 3 HCV) showed double reactivity. Autoantibody binding to CYP2D6(193-212) was inhibited by preincubation with HCV(2977-2996) or CMV(121-140). Recombinant HCV-nonstructural protein 5 and CMV-UL98 proteins also inhibited Ab binding to CYP2D6(193-212). Affinity-purified CYP2D6(193-212)-specific Ab inhibited the metabolic activity of CYP2D6. The demonstrated similarity and cross-reactivity between CYP2D6(193-212) and two unrelated viruses suggests that multiple exposure to viruses mimicking self may represent an important pathway to the development of autoimmunity.

Adolescent↗
PubMed2003

Tracking the source of the hepatitis B virus-specific CD8 T cells during lamivudine treatment.

Lamivudine treatment in chronic hepatitis B leads to the reconstitution of virus-specific T cells in the circulation, but it is not clear whether this is the preferential result of T cell efflux from the liver or lymph nodes. To address this question, the frequency and function of liver-, lymph node-, and blood-derived hepatitis B virus (HBV)-specific CD8 T cells were analyzed in patients treated with lamivudine and undergoing liver transplantation. HBV-specific CD8 T cells, identified in portal lymph nodes, were able to expand in vitro after antigen-specific stimulation and displayed a heterogeneous profile of cytokine production. These findings suggest that the peripherally reconstituted HBV-specific CD8 T cells can originate from precursor cells within lymph nodes.

CD8-Positive T-Lymphocytes↗
PubMed2003

Role of hepatitis B virus specific cytotoxic T cells in liver damage and viral control.

To understand the role of cytotoxic T cells in liver damage and viral control, we used human histocompatibility leukocyte antigen (HLA)-peptide tetramers that allow direct ex vivo quantification of circulating and liver-infiltrating HBV-specific CD8 cells. Studies were carried out in two groups of patients, one without liver inflammation and minimal HBV replication and the other with liver damage and inflammation along with a high level of viral replication. Contrary to expectation, a high frequency of intrahepatic HBV-specific CD8 cells was found in the former group, i.e., the absence of hepatic immunopathology. In the replicating viraemic group, the virus specific T cells were diluted among the liver infiltrates; although with the massive cellular infiltration that was present, the absolute number was similar. It was also shown that in the low viraemia group the reservoir of CD8+ cells present in the circulation was able to expand after specific virus recognition and that this was not detectable in highly viraemic patients with liver inflammation. These results show that inhibition of virus replication can be independent of liver damage and when the HBV-specific CD8 response is unable to control virus replication it may contribute to liver pathology not only directly but by causing recruitment of non-virus specific T cells.

Alanine Transaminase↗
PubMed2003

Extracorporeal liver support with molecular adsorbents recirculating system in patients with severe acute alcoholic hepatitis.

BACKGROUND/AIMS: The mortality of patients with severe acute alcoholic hepatitis (AH) remains high, leading to interest in the use of extracorporeal liver support. The molecular adsorbents recirculating system (MARS) is a liver support device based upon a hollow fibre module in which the patient's blood is dialyzed across an albumin-impregnated membrane. The aim of this paper is to assess the safety, efficacy and feasibility of using MARS in patients with severe AH. METHODS: Eight patients (all encephalopathic; hepatorenal syndrome: Type 1, five patients; Type 2, two patients) were treated with MARS. Clinical, biochemical and haemodynamic assessments were done. RESULTS: Five patients were discharged from hospital, and four are alive at 3 months of follow-up, compared with an estimated survival of about 20%. There were significant improvement in serum bilirubin (P=0.008), creatinine (P=0.02), prothrombin time (P=0.04), and grade of encephalopathy (P=0.05). Sustained improvements in mean arterial pressure, systemic vascular resistance and cardiac output were observed. Thrombocytopaenia was the only MARS-related adverse event observed. CONCLUSIONS: MARS resulted in improved liver biochemistry, cardiovascular haemodynamics, renal function and encephalopathy in patients with severe AH, with an apparent reduction in mortality. On this basis, a multi-centre, randomized clinical trial has been initiated.

Acute Disease↗
PubMed2003

Anti-tumor necrosis factor-alpha monoclonal antibody therapy in severe alcoholic hepatitis.

BACKGROUND/AIMS: Severe alcoholic hepatitis (AH) is associated with high mortality. Tumor necrosis factor-alpha (TNFalpha) has been demonstrated to play an important role in its pathophysiology. METHODS: Twelve patients with biopsy-confirmed AH and a Maddrey discriminant factor >32 were treated with a single infusion of the anti-TNF monoclonal antibody Infliximab at a dose of 5mg/kg body weight. Serial measurements were made for various cytokines using specific enzyme-linked immunoassays (ELISA). In four patients, liver biopsy samples were available pretreatment and on day+28 of therapy. RESULTS: Ten of the 12 patients are alive at a median of 15 (12-20) months. Two patients died within 30 days from septicemia. Serum bilirubin levels, Maddrey score, neutrophil count and C-reactive protein fell significantly within the first month. There was an early, though not significant, decrease in plasma levels of proinflammatory cytokines (interleukins (IL)-1beta, IL-6, IL-8, interferon-gamma), whereas plasma levels of TNFalpha remained near the sensitivity limit of the assay throughout the treatment course. While TNFalpha mRNA expression in the liver did not change, expression of IL-8, a cytokine regulated mainly by TNFalpha, was almost absent on day+28. CONCLUSIONS: Our data suggest that randomized controlled trials of anti-TNF antibody in severe AH are warranted.

Antibodies, Monoclonal↗
PubMed2003

Liver failure: basis of benefit of therapy with the molecular adsorbents recirculating system.

Accumulation of albumin-bound toxins is known to occur in liver failure, and to variable extents is responsible for the associated end-organ dysfunctions (kidney, circulation, brain). The toxin-binding and scavenging functions of albumin are exploited in albumin dialysis for removal of these toxins. The extracorporeal liver support device known as molecular adsorbents recirculating system (MARS) is based on dialysis across an albumin-impregnated membrane, using 20% albumin as dialysate. Charcoal and anion exchange resin columns in the circuit help cleanse and regenerate the dialysate. Clinical studies over the last few years have demonstrated proven reduction in hyperbilirubinaemia, along with an improvement in encephalopathy, systemic haemodynamics and renal function in liver failure patients, as well as apparent improvement in survival. The results of larger controlled clinical trials, as well as studies investigating the pathophysiological basis of its effect, are awaited.

Albumins↗
PubMed2003

Progress report of a Phase I study of the intracerebral microinfusion of a recombinant chimeric protein composed of transforming growth factor (TGF)-alpha and a mutated form of the Pseudomonas exotoxin termed PE-38 (TP-38) for the treatment of malignant brain tumors.

TP-38 is a recombinant chimeric targeted toxin composed of the EGFR binding ligand TGF-alpha and a genetically engineered form of the Pseudomonas exotoxin, PE-38. After in vitro and in vivo animal studies that showed specific activity and defined the maximum tolerated dose (MTD), we investigated this agent in a Phase I trial. The primary objective of this study was to define the MTD and dose limiting toxicity of TP-38 delivered by convection-enhanced delivery in patients with recurrent malignant brain tumors. Twenty patients were enrolled in the study and doses were escalated from 25 ng/mL to 100 with a 40 mL infusion volume delivered by two catheters. One patient developed Grade IV fatigue at the 100 ng/mL dose, but the MTD has not been established. The overall median survival after TP-38 for all patients was 23 weeks whereas for those without radiographic evidence of residual disease at the time of therapy, the median survival was 31.9 weeks. Overall, 3 of 15 patients, with residual disease at the time of therapy, have demonstrated radiographic responses and one patient with a complete response and has survived greater than 83 weeks.

Adult↗
PubMed2003

Treatment of phenytoin toxicity by the molecular adsorbents recirculating system (MARS).

PURPOSE: Toxicity is common in patients of epilepsy treated with phenytoin (PHT), requiring careful drug level monitoring and supportive care. Specific treatment options are limited, although charcoal haemofiltration has been used previously. We attempted to demonstrate that severe PHT toxicity can be treated successfully with the Molecular Adsorbents Recirculating System (MARS). The mechanism of drug removal by the system also was studied. METHODS: A 45-year-old patient of status epilepticus with acute renal failure and severe PHT toxicity, associated with cardiac arrhythmias, hepatotoxicity, and altered sensorium, was treated with the MARS, a blood-purification system based on albumin dialysis, and including a charcoal filter, for 11.5 h. Serum PHT levels and blood levels of oxygen-based free radicals (by electron paramagnetic resonance spectroscopy) were measured before and after treatment. RESULTS: Serum total and free PHT levels declined sharply (32 to 11 microM and 9.8 to 2.0 microM, respectively), with clinical improvement and a 65% reduction in measured oxidative stress. The mechanism of drug removal, deduced by measuring PHT in the dialysate collected from different segments of the MARS circuit, was by clearance from blood into the albumin dialysate, and ultimately removal by the charcoal filter. CONCLUSIONS: The observed removal of PHT by MARS, along with the clinical improvement of the patient and reduction of the associated oxidative stress after treatment, indicates that MARS offers a promising option in PHT toxicity.

Anticonvulsants↗
PubMed2003

Induced hyperammonemia alters neuropsychology, brain MR spectroscopy and magnetization transfer in cirrhosis.

Hyperammonemia is a universal finding after gastrointestinal hemorrhage in cirrhosis. We administered an oral amino acid solution mimicking the hemoglobin molecule to examine neuropsychological changes, brain glutamine levels, and brain magnetization transfer ratio (MTR). Forty-eight metabolically stable patients with cirrhosis and no evidence of "overt" hepatic encephalopathy (HE) were randomized to receive 75 g of amino acid solution or placebo; measurements were performed before and 4 hours after administration. Neuropsychological tests included the Trails B Test, Digit Symbol Substitution Test, memory subtest of the Randt battery, and reaction time. Plasma was collected for ammonia and amino acid measurements, and brain metabolism was studied using proton magnetic resonance (MR) spectroscopy in the first 16 randomized patients. In 7 other patients, MTR was measured. A significant increase in ammonia levels was observed in the amino acid group (amino acid group, 76 +/- 7.3 to 121 +/- 6.4 micromol/L; placebo, 83 +/- 3.3 to 78 +/- 2.9 micromol/L; P <.001). Neuropsychological function improved significantly in the placebo group, but no significant change in neuropsychological function was observed in the amino acid group. Brain glutamate/glutamine (Glx)/creatine (Cr) ratio increased significantly in the amino acid group. MTR decreased significantly from 30 +/-2.9 to 23 +/- 4 (P <.01) after administration of the amino acid solution. In conclusion, an improvement in neuropsychological test results followed placebo, which was not observed in patients administered the amino acid solution. Induced hyperammonemia resulted in an increase in brain Glx/Cr ratio and a decrease in MTR, which may indicate an increase in brain water as the operative mechanism.

Amino Acids↗
PubMed2003

Peripheral blood mononuclear cell expression of toll-like receptors and relation to cytokine levels in cirrhosis.

Activation of macrophages by endotoxin is assumed responsible for increased circulating tumor necrosis factor alpha (TNF-alpha) and soluble TNF receptor (sTNFR) levels in cirrhosis. Relevant to this is expression of Toll-like receptor (TLR) 4 and TLR2, which is critically involved in production of TNF-alpha in response to endotoxin and Gram-positive microbial stimuli, respectively. The first studies on this in cirrhosis are reported here. In 36 cirrhotic patients and 32 controls, we measured (1) circulating endotoxin, TNF-alpha, and sTNFR levels; (2) peripheral blood mononuclear cell (PBMC) expression of TLR4 and TLR2, and (3) in vitro TNF-alpha production by PBMCs stimulated with endotoxin or Staphylococcus aureus enterotoxin B (SEB). PBMC expression of TLR2, circulating TNF-alpha levels, and in vitro TNF-alpha production were reassessed after supplementation with a synbiotic regimen known to increase intestinal levels of Gram-positive bacteria. Endotoxin, TNF-alpha, and sTNFR levels were significantly increased in cirrhosis. Endotoxin levels did not correlate significantly with other parameters. PBMC expression of TLR2 but not TLR4 was significantly up-regulated in cirrhosis and correlated significantly with serum TNF-alpha and sTNFR levels. In vitro TNF-alpha production by PBMCs stimulated by SEB was significantly blunted. Supplementation with the synbiotic regimen resulted in significant up-regulation of PBMC expression of TLR2. Serum TNF-alpha levels were further increased and in vitro TNF-alpha production further reduced in most patients. In conclusion, up-regulation of PBMC expression of TLR2 but not TLR4 occurs in cirrhosis, which implies, contrary to previous assumptions, an important stimulatory role for Gram-positive microbial components but not endotoxin. TLR2 likely contributes to increased circulating TNF-alpha and sTNFR levels in cirrhosis.

Administration, Oral↗