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Biomedical subjects

P M Hall

Publications and source records attributed to P M Hall.

At least 19 recordsLinked to original sources
PubMed2006

Assessing glomerular filtration rate by estimation equations in kidney transplant recipients.

Surveillance of glomerular filtration rate (GFR) is crucial in the management of kidney transplant recipients. With special emphasis on serum creatinine (SCr) calibration assay, we assessed the performance of estimation equations as compared to iothalamate GFR (iGFR) in 209 patients using the modification of diet in renal disease (MDRD), Nankivell and Cockcroft-Gault methods. Fifty-five percent of patients were treated with a calcineurin inhibitor (CNI) and all were taken trimethroprim-sulfametoxazole at the time of SCr measurement. The mean iGFR was 44 +/- 26 mL/min/1.73 m2. The MDRD equation showed a median difference of 0.9 mL/min/1.73 m2 with 53% of estimated GFR within 20% of iGFR. Median differences were 7.5 and 7.0 mL/min/1.73 m2 for Nankivell and Cockcroft-Gault formulas, respectively. The accuracy of the Nankivell and Cockcroft-Gault formulas was such that only 38% and 37% of estimations, respectively, fell within 20% of iGFR. The performance of all equations was not uniform throughout the whole range of GFR, with some deterioration at the extremes of GFR levels. In addition, good performance of the MDRD equation was seen in subjects taking CNI. In conclusion, the overall performance of the MDRD equation was superior to the Nankivell and Cockcroft-Gault formulas in renal transplant recipients including subjects treated with CNI.

Adult↗
PubMed2001

Role of non-alcoholic steatohepatitis in methotrexate-induced liver injury.

BACKGROUND AND AIMS: Hepatotoxicity, especially liver fibrosis, is the major concern with long-term, 'low-dose' oral methotrexate (MTX) therapy for psoriasis. The histological features are non-specific and resemble those of non-alcoholic steatohepatitis (NASH). Moreover, most of the risk factors of MTX-induced liver injury are also associated with NASH. In this study, we investigate whether NASH contributes to the prevalence and progression of MTX-induced liver injury in patients receiving MTX for psoriasis. METHODS: Clinical details, including MTX dosage schedules and risk factors for liver injury, was documented for 24 patients on long-term MTX therapy for psoriasis. Serial liver biopsies were graded according to the Roenigk classification scale and a recently proposed grading and staging system for NASH. RESULTS: Thirteen of the 17 patients who had a NASH-like pattern of liver injury also had the risk factors for NASH obesity and/or diabetes, and all had progressive liver injury. The other four patients had no risk factors, but a mean cumulative dose of 6.5 g. Seven patients, who did not have a NASH-like pattern of injury, had a mean cumulative dose of 3.8 g. There was a positive correlation between the cumulative dose, risk factors and progression when the biopsies were scored by the modified grading and staging classification for NASH, but not with the Roenigk system. CONCLUSIONS: Non-steatohepatitis, probably aggravated by MTX, is an important cause of liver injury in patients on long-term, 'low-dose' MTX treatment for psoriasis. In addition, MTX alone can cause a NASH-like pattern of injury that is at least, in part, caused by a higher cumulative dose.

Adult↗
PubMed2001

Strategies to prevent progression of renal disease.

Clinical studies show that several strategies can prevent or slow the progression of renal disease in patients with or without diabetes. This paper reviews current theories of how renal disease develops and progresses and what clinical studies indicate about how to prevent or slow the process.

Animals↗
PubMed2000

Increased ecto-metallopeptidase activity in cells undergoing apoptosis.

Release from the cell surface of a variety of growth factors, cytokines, and proteases follows exposure to genetically stressful agents capable of inducing apoptosis and necrosis. Increased ectoprotease activity is responsible for their release. We show that increased activity of several metalloproteases on the HeLa cell surface occurs after stresses due to UVC, actinomycin D, cycloheximide, and cisplatinum, which induce the release of transforming growth factor-alpha (TGFalpha) and other bioactive molecules. The ectoprotease activities increase preferentially on apoptotic cells, while little change occurs in viable cells. Gross decreases, except for the putative TGFalphaase activity, accompany necrosis. These changes may contribute to tissue repair and the absence of an inflammatory reaction to apoptotic cell death. They appear to be due to preferential enzyme activation or to retention by cells undergoing significant categorical decreases in protein content.

Aminopeptidases↗
PubMed2000

Localization of N-acetyltransferases NAT1 and NAT2 in human tissues.

Human acetyl coenzyme A-dependent N-acetyltransferase (EC 2.3.1.5) (NAT) catalyzes the biotransformation of a number of arylamine and hydrazine compounds. NAT isozymes are encoded at 2 loci; one encodes NAT1, formerly known as the monomorphic form of the enzyme, while the other encodes the polymorphic NAT2, which is responsible for individual differences in the ability to acetylate certain compounds. Human epidemiological studies have suggested an association between the "acetylator phenotype" and particular cancers such as those of the bladder and colon. In the present study, NAT1- and NAT2-specific riboprobes were used in hybridization histochemistry studies to localize NAT1 and NAT2 mRNA sequences in formalin-fixed, paraffin-embedded human tissue sections. Expression of both NAT1 and NAT2 mRNA was observed in liver, gastrointestinal tract tissues (esophagus, stomach, small intestine, and colon), ureter, bladder, and lung. In extrahepatic tissues, NAT1 and NAT2 mRNA expression was localized to intestinal epithelial cells, urothelial cells, and the epithelial cells of the respiratory bronchioles. The observed heterogeneity of NAT1 and NAT2 mRNA expression between human tissue types may be of significance in assessing their contribution to known organ-specific toxicities of various arylamine drugs and carcinogens.

Arylamine N-Acetyltransferase↗
PubMed2000

A new treatment for unresectable liver tumours: long-term studies of electrolytic lesions in the pig liver.

The majority of liver tumours are inoperable and an alternative treatment to surgical resection is urgently needed. Electrolysis has been investigated in a rat model and the procedure is safe, with accurate and predictable effects. The necrosis produced has also been shown to cause destruction of tumour deposits in the rat liver. A similar evaluation in a large animal model was necessary before clinical trials could commence. Using platinum electrodes connected to a d.c. generator, areas of hepatic necrosis were created in the pig liver. Animals were killed at various time points after treatment to assess the extent of healing. Treatment was uneventful and all animals made a full recovery. No animal died from the treatment or had to be killed prematurely. After 2 days of treatment, healing was minimal but at successive time points there was progressive evidence of healing, such that after 4 months, the original electrolytic lesion was greatly reduced in size and the large area of necrosis seen at the early time points was largely replaced by a fibrous scar with only small islands of necrotic tissue. In a large animal model, electrolysis is a safe method for creating areas of hepatic necrosis. The lesions heal with time and are associated with minimal morbidity. The results support a trial of electrolysis in patients with unresectable liver tumours.

Animals↗
PubMed1999

The effects of dietary iron overload on fumonisin B1-induced cancer promotion in the rat liver.

The present study was performed to determine whether excess hepatic iron modulates the cancer-initiating and promoting properties of FB1. Thirty-eight male F344 rats were divided into four dietary treatment groups: (i) control diet (AIN, n = 8); (ii) FB1 250 mg/kg diet (FB1, n = 10); (iii) 1-2% carbonyl iron (CI, n = 10); or (iv) FB1 plus iron loading (FB1/CI, n = 10) for 5 weeks (2 x 2 factorial design). Hepatic iron concentrations in iron-loaded animals at 5 weeks were 444 +/- 56 (CI) and 479 +/- 80 micromol/g dry weight (FB1/CI) (mean +/- SEM). All the FB1-fed rats, in the presence or absence of CI, developed a toxic hepatitis with a 4-fold rise in serum alanine transaminase (ALT) levels. FB1 appeared to augment iron-induced hepatic lipid peroxidation, as measured by the generation of thiobarbituric acid reacting substances (TBARS) in liver homogenates (P < 0.0001). Morphometric analysis showed that FB1 caused a significantly greater mean +/- SEM number of 'enzyme-altered' foci and nodules per cm2 (5.34 +/- 1.42 vs. 1.50 +/- 0.52, P < 0.05), as well as a greater area (%) of liver occupied by foci and nodules (0.33 +/- 0.12% vs. 0.05 +/- 0.03%, P < 0.001), compared with FB1/CI. The addition of FB1 to dietary iron loading caused a shift in distribution of iron from hepatocytes to Kupffer cells, probably due to phagocytosis of necrotic iron-loaded hepatocytes. In conclusion, (i) FB1 appears to cause toxicity in the liver independently from effects on lipid peroxidation; (ii) FB1 has a potentiating effect on iron-induced lipid peroxidation; and (iii) dietary iron loading appears to protect against the cancer promoting properties of FB1, possibly due to a stimulatory effect of iron on hepatocyte regeneration.

Animals↗
PubMed1999

Medical management of aldosterone-producing adenomas.

BACKGROUND: No data are available on the long-term medical management of aldosterone-producing adenomas. OBJECTIVE: To demonstrate the efficacy of medical management of aldosterone-producing adenomas in terms of blood pressure and serum potassium concentration and to discuss morbidity associated with medical management. DESIGN: Retrospective cohort study. SETTING: Large tertiary care referral center. PATIENTS: 24 patients with documented aldosterone-producing adenomas who were treated medically for at least 5 years. MEASUREMENTS: Aldosterone excretion rate, plasma renin activity, and size and location of adenomas (by computed tomography). Blood pressure and serum electrolytes were measured at the time of diagnosis and last follow-up. RESULTS: From the time of diagnosis to the time of last follow-up, systolic blood pressure decreased from 175 mm Hg to 129 mm Hg (95% CI for difference, 37.1 to 53.8 mm Hg) and diastolic blood pressure decreased from 106 mm Hg to 79 mm Hg (CI for difference, 20.8 to 33.9 mm Hg). Serum potassium concentration increased from 3.0 mmol/L to 4.3 mmol/L (CI for difference, 1.1 to 1.5 mmol/L). CONCLUSIONS: Medical management of aldosterone-producing adenomas is a viable option for controlling blood pressure and serum potassium concentration.

Adenoma↗
PubMed1999

Hiring criteria, duties, and professional growth opportunities for residential staff at schools for the deaf: a survey.

Seventy-three schools identifying themselves as having a residential program for deaf students were surveyed to determine demographic information about dormitory staff, qualifications required for employment in the residential program, opportunities for continuing education, and issues relating to the roles and responsibilities of dorm employees. The data showed that schools are committed to providing in-service education for the dorm workers but have minimal educational requirements for employment in their residential programs. The data were compared to the Conference of Educational Administrators of Schools and Programs for the Deaf (CEASD) Certification Requirements for Dormitory Counselors. Recommendations are made in regard to the updating of the CEASD certification requirements; the authors also recommend that schools make a stronger commitment to upholding those requirements.

Career Mobility↗
PubMed1998

Characterization of age- and dose-related outcomes of duck hepatitis B virus infection.

Experimental inoculation of naive ducks with duck hepatitis B virus (DHBV) can lead to one of three outcomes, namely, persistent viremia, transient infection with or without viremia, or no evidence of infection. The ability of individual ducks to resolve DHBV infection was found to be linked to the age of the duck at the time of inoculation and the dose of inoculated virus. (1) In recently hatched ducks inoculated intravenously (i.v.) with 4 x 10(4) DHBV DNA genomes, a switch from persistent viremia to transient antibody appearance was seen at an age of inoculation between 7 and 14 days. A 25-fold increase in the dose of virus (1 x 10(6) DHBV genomes) delayed this switch by 7 days. (2) When 4-month-old ducks were inoculated i.v. with different doses of virus, only those receiving the highest dose (2 x 10(11) DHBV genomes) showed viremia and extensive viral replication and histological changes in the liver; 2/3 ducks in this group had a transient infection, while the third duck had viral replication and histological changes in the liver that were still present at day 120 postinoculation (p.i.). In all ducks receiving lower doses (1 x 10(3), 1 x 10(6), 1 x 10(9) DHBV genomes) antibodies to viral surface and core antigens developed without detectable viral replication in the liver on days 6, 9, or 12 p.i. (3) When 10- to 16-month-old ducks were inoculated i.v. with 2 x 10(11) DHBV genomes, all showed extensive viral replication in hepatocytes and mild to moderate histological changes in the liver on days 4 or 6 p.i. In 4/5 ducks viremia was not detected, anti-surface antibodies were first detected on day 8 p.i., and viral DNA and antigen were cleared from the liver by days 35-47 p.i. The remaining duck became viremic with persistence of virus in the liver until at least day 46 p.i. The findings of the study are consistent with a model for noncytopathic viruses (R. M. Zinkernagel (1996) Science 271, 173-178).

Age Factors↗
PubMed1998

Experimental study of electrolysis-induced hepatic necrosis.

BACKGROUND: One of the most promising but unexplored methods for treating patients with irresectable liver tumours is electrolysis. This study examined the effect of increasing 'current dose' on the volume of the lesion induced in normal rat liver. METHODS: A direct current generator, connected to platinum electrodes implanted in the rat liver, was used to examine the effect of (1) varying current doses from 1 to 5 coulombs and (2) electrode separation (2 or 20 mm), on the volume of liver necrosis. RESULTS: There was a significant correlation (P < 0.001) between the current dose and the volume of necrosis produced for each electrode separation. Placing the electrodes 2 mm apart resulted in smaller total volumes of necrosis than placing them 20 mm apart when anode lesions were significantly larger than cathode lesions (P< 0.05). Liver enzymes (aspartate aminotransferase, alanine aminotransferase) were significantly raised 1 day after treatment (P < 0.001) and predicted the total volume of hepatic necrosis (P < 0.001). CONCLUSION: Predictable and reproducible areas of liver necrosis are produced with electrolysis. If these results extrapolate to larger animal models, this technique has potential for patients with irresectable primary and secondary liver tumours.

Animals↗
PubMed1998

Gadolinium chloride suppresses hepatic oval cell proliferation in rats with biliary obstruction.

Liver injury due to bile duct ligation (BDL) is histologically characterized by cholestasis, bile ductular proliferation, hepatocellular damage, portal fibrosis, and ultimately biliary cirrhosis. Stem cells within the liver may act as progenitor cells for small epithelial cells termed oval cells that can differentiate into bile duct cells or hepatocytes, whereas myofibroblasts are the principal source of collagen production in fibrosis. The aims of this study were to determine 1) whether BDL induces oval cell proliferation and 2) whether blockade of Kupffer cells affects oval cell proliferation, bile duct proliferation, and myofibroblast transformation in experimental biliary obstruction. Male Sprague-Dawley rats were divided into two groups to receive either a single dose of gadolinium chloride (a selective Kupffer cell blocking agent) or vehicle. One day later, the gadolinium- and vehicle-treated groups were further subdivided to receive either BDL or sham operation. The rats were sacrificed on day 7 postoperatively. Serum was collected for measurement of aspartate aminotransferase, gamma-glutamyl transpeptidase, and bilirubin levels. Liver tissue was taken for evaluation of fibrosis, bile ductular cells, oval cells, and myofibroblasts. BDL resulted in elevated aspartate aminotransferase, gamma-glutamyl transpeptidase, and bilirubin in serum, and gadolinium pretreatment did not modify these effects. BDL induced marked oval cell proliferation, which was completely prevented by gadolinium pretreatment. Gadolinium did not affect the induction of bile duct expansion or myofibroblasts after BDL. We conclude that experimental biliary obstruction induces oval cell proliferation, which can be prevented by gadolinium pretreatment. This suggests that bile ductular proliferation and myofibroblast transformation are not mediated by Kupffer cells and that ductular proliferation can proceed in the absence of oval cells. Alternatively, gadolinium may directly affect oval cell proliferation after BDL.

Animals↗
PubMed1998

Surgical resection for hepatocellular carcinoma in Cape Town--a clinical and histopathological study.

OBJECTIVE: Review of surgical resections performed for hepatocellular carcinoma (HCC) at our institution between 1990 and 1996, histology of resected specimens, and clinical outcome. DESIGN: Retrospective and prospective study of 14 patients who underwent resection for HCC. SETTING: The Hepatobiliary Unit and Liver Clinic, Groote Schuur Hospital, Cape Town. PATIENTS: Fourteen patients who underwent liver resections for HCC. INTERVENTIONS: Hepatic resections using prolonged vascular inflow occlusion. OUTCOME MEASURES: Clinical outcome and disease-free survival following resection. RESULTS: Fourteen patients (5.6% of the total number presenting with HCC) underwent liver resection for HCC at our institution between 1990 and 1996. There were 7 men, median age 40 years (range 18-74 years). Only 2 patients were black, and only 1 of these patients had evidence of hepatitis B virus (HBV) infection in the liver. Extensive liver resections were often required. The mean (SD) ischaemic time was 81 (26) minutes and mean estimated blood loss was 938 (649) ml. During hospital admission, 1 patient developed a minor bile leak that settled spontaneously, and 1 patient suffered a stroke and died. The mean hospital stay following operation was 12 days (range 7-21 days). Disease-free patient survival at 1, 2 and 3 years was 85%, 75%, and 62%, respectively. Histopathology of the resected specimens showed that 10 of 14 tumours had arisen in non-cirrhotic livers. Mean tumour size was 10.6 (4.6) cm. Only 1 specimen showed the fibrolamellar variant of HCC. CONCLUSIONS: Only a small proportion of patients with HCC seen at Groote Schuur Hospital were eligible for resection, and only a minority of these had HBV-associated 'African' HCC. The results of hepatic resection at our institution compare favourably with literature reports, despite the relatively large size of the tumours. It is of interest that most tumours arose in non-cirrhotic livers. There was no evidence of proliferation of 'oval-like' cells in non-neoplastic liver tissue.

Adolescent↗
PubMed1997

A technique for obtaining repeated liver biopsies from rats.

Many morphological, pharmacological and toxicological studies of hepatotoxicity require frequent sampling of liver over time. In the past this has been achieved by including large numbers of animals in the study and killing subgroups at different times. In this paper we describe a technique for repeated liver biopsy that procures sufficient liver tissue for histopathological assessment and for additional studies, for example measurement of hepatic iron concentration or vitamin A measurement. The advantages and disadvantages of this technique are discussed.

Animals↗
PubMed1997

Use of artificial sweeteners to promote alcohol consumption by rats.

Cirrhosis may be reliably produced in rats by exposing them intermittently to low levels of carbon tetrachloride vapour while feeding alcohol in the Lieber-DeCarli liquid diet. Providing the alcohol in drinking water that has been sweetened with sucrose is a cheaper and more convenient method but it does not yield reliable results. This study aimed to determine whether alcohol in drinking water sweetened with artificial sweeteners would give adequate alcohol intake to achieve the desired hepatic effects. Rats were fed alcohol (8% v/v) in drinking water sweetened with sucrose (5% w/v) (n = 12), or with one of the artificial sweeteners aspartame (0.025%), saccharin (0.025%) or cyclamate (0.05%) (n = 8 per agent). During the alcohol treatment the animals were exposed to carbon tetrachloride vapour, 40 ppm, six hours per night for five nights per week, over a period of 14 weeks. All groups achieved good alcohol intakes of 5-6 g/kg/day. Only one rat, in the aspartame group, became cirrhotic; all the others had varying degrees of fibrosis which did not differ significantly among the treatments. Although it was not effective in reliably achieving cirrhosis, sweetening the alcohol solution with artificial sweeteners led to reasonable alcohol intakes with resultant hepatic fibrosis, and without the high carbohydrate intake which occurs when sucrose is used.

Alcohol Drinking↗
PubMed1997

Ethanol feeding enhances inflammatory cytokine expression in lipopolysaccharide-induced hepatitis.

Elevated concentrations of plasma tumour necrosis factor (TNF)-alpha, interleukin (IL)-1 and IL-6 have been detected in patients with alcoholic hepatitis and have been implicated in the pathogenesis of hepatocyte necrosis. The present study used a rat model to conduct a detailed histological and biochemical examination of the expression of various pro-inflammatory cytokines and associated liver pathology in ethanol-potentiated lipopolysaccharide (LPS)-induced liver injury. Male Wistar rats were pair-fed either the control or ethanol-containing (36% of caloric intake as ethanol) form of the Lieber-DeCarli liquid diet for 6 weeks. Liver injury was induced by the i.v. injection of LPS (1 microgram/g bodyweight), with animals being killed at 0, 1, 3, 6, 12 and 24 h after injection. At the later time points, plasma transaminase and transpeptidase activities were significantly elevated in ethanol-fed LPS-treated rats compared with control-fed LPS-treated animals. At these times after LPS treatment, hepatocytes in ethanol-fed animals displayed fatty change and necrosis with an associated neutrophil polymorph infiltrate. Time course analysis revealed that plasma TNF-alpha (1-3 h post-LPS) and IL-6 (3 h post-LPS) bioactivity was significantly elevated in ethanol-fed compared with control-fed animals. No difference was seen in plasma IL-1 alpha concentration (maximal in both groups 6 h post-LPS). The expression of TNF-alpha, IL-1 alpha, IL-1 beta and IL-6 mRNA were elevated between 1 and 6 h post-LPS in the livers of both control and ethanol-fed rats. However, ethanol-fed LPS-treated animals exhibited significantly higher maximal expression of IL-1 and IL-6 mRNA. Comparison of the appearance of cytokine mRNA and plasma bioactivity indicated an effect of ethanol feeding on post-transcriptional processing and/or the kinetics of the circulating cytokines. Elevated levels of both hepatic cytokine mRNA expression and the preceding plasma cytokines are presumably a necessary prerequisite for hepatic injury seen in this model and, therefore, possibly for the damage seen in human alcoholics. Further studies using this model may lead to significant advances in our understanding of the pathogenic mechanisms of alcoholic liver disease in humans.

Alanine Transaminase↗
PubMed1996

Small gauge gelfoam plug liver biopsy in high risk patients: safety and diagnostic value.

The performance of a percutaneous core biopsy of the liver may be contraindicated in patients at higher risk of haemorrhage. In this clinical setting, gelfoam plug embolization of the needle track has been proposed to minimize haemorrhagic complications of biopsy. In the present study, gelfoam plug liver biopsy was performed in 51 consecutive patients at increased risk of haemorrhage. An 18 gauge spring-loaded disposable cutting needle was used through a 4 French sheath. The biopsy track was embolized by three to four gelfoam pledgets. In every patients, the cores of hepatic tissue were adequate for histopathological diagnosis. There were no fatalities and no serious complications. Gelfoam plug liver biopsy using this needle and sheath in combination appears to be a safe procedure and produces diagnostic cores for histological analysis. This method represents an alternative to transjugular liver biopsy and is technically more straight-forward to perform.

Adolescent↗