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Biomedical subjects

A K Burroughs

Publications and source records attributed to A K Burroughs.

At least 163 records · Page 9Linked to original sources
PubMed1995

Endoscopic detection of ischaemia with a new probe indicates low oxygenation of gastric epithelium in portal hypertensive gastropathy.

Changes in mucosal blood flow may be important in the pathogenesis of many conditions. Study of mucosal blood perfusion is difficult, and available methods have significant technical limitations. This study describes the development of an instrument for endoscopy, which indicates blood flow indirectly, by measuring the quantity of tissue oxygen that can diffuse from the mucosa to a luminal surface electrode. The instrument was used through an endoscope in patients with portal hypertension (n = 14), scleroderma (n = 3), disease controls (n = 7), and normal controls (n = 11). In portal hypertension readings were one quarter that in normal controls in both antrum (geometric mean (SEM) 35 (1.1)), nanoamps v 137 (1.1), and upper corpus 34 (1.1) v 125 (1.1)). Scleroderma patients showed greatly reduced oxygen readings in both antrum (18 (1.2)) and corpus (24 (1.2)), an expected but hitherto undiscovered result. These differences are highly significant (p = 0.0001), and the findings suggest that tissue hypoxia may contribute to mucosal changes in portal hypertensive gastropathy and in scleroderma.

Epithelium↗
PubMed1995

Natural history of bacteriuria in women with primary biliary cirrhosis and the effect of antimicrobial therapy in symptomatic and asymptomatic groups.

Primary biliary cirrhosis (PBC) patients have an increased incidence of recurrent urinary tract infection compared with patients with other chronic liver diseases. The course of significant asymptomatic and symptomatic bacteriuria in women with PBC was evaluated: consecutive patients were screened for bacteriuria at their outpatient appointments. Bacteriuric patients who were asymptomatic (n = 21) were randomised to receive antimicrobial therapy (n = 11), or no therapy (n = 10). Bacteriuric patients who were symptomatic (n = 13) were treated. All were followed up by weekly dipslide examination of urine. The course of bacteriuria in the 13 symptomatic and 11 asymptomatic treated patients was similar in terms of the medium interval between successive infective episodes (three and four weeks respectively), the number of relapses (six and seven) and reinfections (14 and 18). Most untreated asymptomatic patients became abacteriuric spontaneously but became reinfected with a different organism during the study period. A separate group of 24 PBC patients with no previous bacteriologically proved urinary tract infection was followed weekly in a similar fashion: seven (29%) became bacteriuric for two to four weeks during a three month period. This study suggests that treatment of recurrent bacteriuric episodes in PBC patients does not alter the natural history of their infection. The long term implication of periodically infected urine in these patients is currently unknown.

Adult↗
PubMed1995

Anti-tuberculosis medication and the liver: dangers and recommendations in management.

In the light of three deaths due to liver failure secondary to anti-tuberculosis therapy at the Royal Free Hospital, we have reviewed the current literature, and asked--How common is liver dysfunction with anti-tuberculosis medications and how might it be prevented? Anti-tuberculosis chemotherapy is associated with abnormalities in liver function tests in 10-25% of patients. Clinical hepatitis develops in about 3%, though estimates vary, and in these patients there is likely to be significant morbidity and mortality. On the basis of reported cases of tuberculosis, 160 patients in England and Wales can be expected to develop drug-induced hepatitis due to anti-tuberculosis therapy each year. There are published guidelines from the British and American Thoracic Societies regarding the choice of drug therapy for tuberculosis. Current recommendations with regard to monitoring liver function, and what to do when these tests become abnormal, vary considerably. We suggest a protocol for using liver function tests to monitor for liver damage, and give recommendations on what action to take when these become abnormal.

Antitubercular Agents↗
PubMed1995

Vasoconstrictors in the management of bleeding from oesophageal varices. A clinico-economic appraisal in the UK.

BACKGROUND: Bleeding from oesophageal varices is an uncommon but potentially fatal condition that often leads to expensive hospitalizations in intensive care or high-dependency units. METHODS: To assess the clinical and economic impact of this condition, we have devised a management plan illustrating current clinical practice in the UK. RESULTS: Approximately 6.1 million pounds of NHS resources are devoted to the treatment of 3000 acute hospital admissions for variceal bleeding every year. Vasoconstrictors like vasopressin may save approximately 36 lives per annum for an additional 145 thousand pounds. However, current clinical practice requires vasopressin to be concurrently administered with intravenous glyceryl trinitrate, increasing overall costs by 582 thousand pounds to a total of 6.7 million pounds. The additional cost for each extra life saved is estimated at 16,180 pounds. CONCLUSION: The efficacy of current vasoconstrictors requires further confirmation. In particular, new agents like octreotide (Sandostatin) should be carefully assessed to determine their potential clinical and economic benefits.

Acute Disease↗
PubMed1995

Pharmacological therapy for portal hypertension: rationale and results.

Drug therapy for acute variceal bleeding should be viewed as an adjunct to emergency sclerotherapy. Its role in preventing very early rebleeding (within days) following sclerotherapy needs to be established. The best candidates for such a role are somatostatin and octreotide, but glypressin and vasopressin and nitroglycerin combinations have therapeutic effects in the short-term. Propranolol is the drug for long-term prevention of rebleeding and prevention of the first variceal bleed. For primary prophylaxis it significantly reduces the rate of bleeding, and there is a trend towards reducing mortality. It should be used in cirrhotic patients with large varices. For secondary prophylaxis, propranolol significantly reduces rebleeding but does not improve survival. The reduction in rebleeding is similar to long-term sclerotherapy when compared in randomized studies. There is no value in adding beta-blockers to sclerotherapy compared with sclerotherapy alone, but few studies have evaluated the effects after the eradication of varices. beta-Blockers can be used as the first-line therapy to prevent variceal rebleeding. They also have been shown to reduce the frequency of rebleeding from congestive gastropathy. Many patients do not have a portal pressure reduction with propranolol. The addition of isosorbide mononitrate converts many nonresponders to responders. Current clinical trials are evaluating if therapeutic efficacy is improved by these drug combinations.

Adrenergic beta-Antagonists↗
PubMed1995

Cardiovascular effects of octreotide in patients with hepatic cirrhosis.

Octreotide is thought to reduce splanchnic and variceal blood flow with minimal effects on the systemic circulation in cirrhotic patients with portal hypertension. However, we noticed significant bradycardia in some patients immediately after administration of bolus doses of octreotide. Therefore, we investigated the effect of intravenous octreotide on systemic hemodynamics in 59 patients with cirrhosis. In two double-blind, placebo-controlled protocols, 32 patients received a 25-micrograms bolus and 20 patients received an infusion of 50-micrograms/hr of octreotide/placebo. Immediately after the bolus dose of octreotide was administered, there were significant reductions in pulse rate (77 +/- 3 vs. 65 +/- 3 beats per minute, P < .01) and cardiac output (9.2 +/- 0.8 vs. 7.9 +/- 0.8 L/min; P < .01) and significant increases in mean arterial pressure (81 +/- 3 vs. 87 +/- 3 mm Hg; P < .05), mean pulmonary artery pressure (9.1 +/- 1.0 vs. 16.6 +/- 1.5 mm Hg; P < .01), right atrial pressure (3.8 +/- 0.8 vs. 6.6 +/- 1.0 mm Hg; P < .01), right ventricular pressure (7.1 +/- 0.6 vs. 12.5 +/- 1.3 mm Hg; P < .01), pulmonary capillary wedge pressure (4.8 +/- 0.8 vs. 11.2 +/- 1.4 mm Hg; P < .01), systemic vascular resistance, and pulmonary vascular resistance. Thirty minutes after the start of the infusion, there were significant increases in mean right atrial pressure, right ventricular pressure, pulmonary artery pressure, and pulmonary capillary wedge pressure. This study suggests that intravenous octreotide has significant effects on the systemic circulation in patients with cirrhosis and that these effects appear to be more marked after administration of bolus doses.

Adult↗
PubMed1995

Detection of M2 antibodies in patients with recurrent urinary tract infection using an ELISA and purified PBC specific antigens. Evidence for a molecular mimicry mechanism in the pathogenesis of primary biliary cirrhosis?

Primary Biliary Cirrhosis (PBC) is a chronic liver disease of unknown aetiology. The main characteristic feature of the disease is the presence of circulating antimitochondrial antibodies (AMA) to components (collectively named M2) of the mitochondrial 2-oxo-acid multienzyme complexes; pyruvate, oxoglutarate and branched chain oxo-acid dehydrogenase complexes. As these enzymes are phylogenetically conserved, AMA also exhibit reactivity against a range of microorganisms. PBC patients have an increased incidence of recurrent urinary tract infection (UTI) compared to other chronic liver disease controls. Interestingly, we have recently detected low titre AMA in patients with a history of recurrent UTI but normal liver function using crude bovine heart mitochondrial preparations and immunoblotting techniques. Here we confirm these findings using purified M2 antigens and ELISA. We found that 52% of "normal" subjects with a history of recurrent UTI had AMA specifically to M2 antigens. The percentage was significantly higher than that found for chronic liver disease (19%, p < 0.01) and normal controls (4%, p < 0.001). These results support our hypothesis for molecular mimicry in PBC. We propose that a bacterial trigger, possibly resulting from recurrent UTIs, is responsible for initiating an autoimmune response in a predisposed host because of a cross-reactivity between mitochondrial and bacterial antigens.

Antibody Specificity↗
PubMed1995

Grading of cellular rejection after orthotopic liver transplantation.

All 684 post-orthotopic liver transplantation (OLT) liver biopsies performed at the Royal Free Hospital (RFH) between 1988 and 1993, from 120 patients, were reviewed in order to try to define the relative importance of the histological features of immunosuppression-responsive cellular rejection. Twenty histological features considered to be possible contributors to the diagnosis of cellular rejection were documented in a binary (present/absent) fashion. These features in 106 biopsy specimens obtained 1 to 8 days after OLT were analyzed using stepwise logistic discriminant analysis. All clinical and treatment records were reviewed, and each biopsy specimen was assigned to a diagnostic category depending on these records and follow-up information. Important determinants of the histological diagnosis of cellular rejection (which occurred in 84 of the 106 cases) were moderate/severe mixed portal inflammation, eosinophils, endotheliitis, and bile duct damage. When these all occurred together, the odds of rejection increased 3.6-fold. The original histological diagnosis was recorded, and each biopsy specimen showing cellular rejection was regarded according to the specific criteria of Snover et al., Demetris et al., and a novel RFH scoring system. The latter consists of evaluating portal inflammation, endotheliitis, eosinophils, and bile duct damage, each on a 0 to 3 scale (none, mild, moderate, or severe, respectively) and summation. The resulting cellular rejection score thus can range from 0 to 12. The agreement between the different scoring systems was analyzed using K statistics, and there was good concordance (K, 0.64 to 0.78), despite different histological criteria being used to derive each score. Each system showed a similar degree of sensitivity (87% to 96%). The specificity ranged from 59% to 77%. We conclude that the histological diagnosis of cellular rejection relies mainly on the previously described features of mixed portal inflammation, endotheliitis, eosinophils, and duct damage. There is scope for unification and simplification of the existing grading systems, which depend on differing criteria, and we suggest one such scheme.

Biopsy↗
PubMed1995

Effect of functional grade and etiology on in vivo hepatic phosphorus-31 magnetic resonance spectroscopy in cirrhosis: biochemical basis of spectral appearances.

Hepatic phosphorus-31 magnetic resonance spectroscopy (31P MRS) was undertaken in 85 patients with histologically proven cirrhosis of varying etiologies and functional severity. Reference data were acquired from 16 healthy volunteers who had no history or evidence of liver disease or alcohol abuse. In vivo hepatic 31P MR spectra were acquired with pulse angle 45 degrees and repetition times (TR) of 5 and 0.5 seconds. Peak area ratios of phosphomonoesters (PME), inorganic phosphate (Pi), and phosphodiesters (PDE) relative to beta ATP, and of PME relative to PDE were calculated from spectra acquired at TR 5 seconds. Estimates of saturation effects for individual resonances were obtained by dividing the peak height at TR 5 seconds by that at TR 0.5 seconds to yield a T1-related signal height ratio (SHR). When compared with reference values, the patients with liver disease showed a significantly higher PME/ATP (P < .0001), PME/PDE (P < .0001), PME SHR (P < .001), and Pi SHR (P < .02), and a lower PDE/ATP (P < .001) and PDE SHR (P < .001). The magnitude of these changes increased significantly and progressively with increasing functional impairment. In patients with compensated cirrhosis spectral appearances varied with etiology; thus, patients with postviral cirrhosis showed a significantly higher Pi/ATP; those with alcoholic cirrhosis, a significantly lower PDE/ATP; and those with cirrhosis secondary to primary sclerosing cholangitis, a significantly lower Pi/ATP than the healthy volunteers or other etiological groups. However, spectral appearances did not vary with etiology in patients with decompensated disease. In vitro 31P MRS of perchloric extracts of samples of liver tissue obtained from 10 patients with cirrhosis at transplant hepatectomy showed increases in levels of the soluble PME metabolites, phosphorylcholine and phosphorylethanolamine, and reductions in the levels of the soluble PDE metabolites, glycerophosphorylcholine and glycerophosphorylethanolamine. These changes suggest regenerative activity in cirrhotic livers. The increases in soluble phosphomonoesters in the aqueous extracts accounted for the increased PME/ATP ratio seen in the in vivo spectra, and might account for the increase in PME SHR. The reduction in soluble phosphodiesters in the aqueous extracts did not entirely account for the reduction PDE/ATP ratio seen in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1995

Spontaneous haemoperitoneum caused by ruptured varices in a patient with non-cirrhotic portal hypertension.

OBJECTIVE: To report the case of a patient with a spontaneous, massive and fatal intraperitoneal haemorrhage from porto-systemic collaterals, caused by portal hypertension. We also review the cases of 18 cirrhotic patients with spontaneous bleeding of intraperitoneal varices and no previous abdominal surgery reported in the literature. PATIENT: A 21-year-old man with nodular regenerative hyperplasia, who had not undergone any previous surgery and who had large oesophageal varices diagnosed 3 years previously. CONCLUSION: To our knowledge, this is the first case of spontaneous intra-abdominal bleeding from collateral vessels in a non-cirrhotic patient.

Adult↗
PubMed1994

Donor-specific bone marrow infusion after orthotopic liver transplantation.

Donor-specific bone marrow infusion after organ grafting can induce tolerance in animals. In this randomised controlled study we show it has no benefit in patients undergoing liver transplantation. Of 25 patients, 9 received bone marrow 5 days after a 10 day course of antithymocyte globulin. Immunosuppression was maintained with cyclosporin only. An average of 3.0 rejection episodes per patient was seen in the bone marrow group compared to 3.1 in the controls. Chimerism was not found in peripheral blood or bone marrow of recipients using erythrocyte antigen markers, PCR for donor class II DNA or Y-probe in-situ hybridisation in one female recipient of male liver and bone marrow.

Antigens, Differentiation↗
PubMed1994

Emergency transjugular intrahepatic portasystemic stent shunting as salvage treatment for uncontrolled variceal bleeding.

Creation of a transjugular intrahepatic portasystemic stent shunt (TIPSS) was used as a rescue treatment for patients with variceal bleeding refractory to standard medical and endoscopic treatment. Over a 2-year period 242 episodes of variceal bleeding were treated and emergency shunting was performed on 20 patients with uncontrolled bleeding (Pugh grade A, one; B, seven; C, 12). The procedure was technically successful and controlled bleeding in all patients. Six patients had early rebleeding within 5 days, and further shunting was required in two. Two had late rebleeding related to shunt occlusion and had a further TIPSS procedure followed by portacaval shunting. Twelve patients died within 40 days from liver failure and sepsis, and there were two late deaths after 2 and 6 months, unrelated to bleeding. TIPSS insertion is an effective therapeutic option in patients with acute variceal bleeding refractory to medical and endoscopic treatment. However, despite control of bleeding in this group, the hospital mortality rate was high, reflecting the severity of the underlying liver disease.

Adult↗
PubMed1994

Alteration in vascular reactivity in isolated aortic rings from portal vein-constricted rats.

It has been suggested that increased production of nitric oxide by an inducible nitric oxide synthase isoenzyme is important in the pathogenesis of the vascular abnormalities seen in human beings and animals with portal hypertension. We investigated this hypothesis by studying the in vitro vascular reactivity of isolated aortic rings from portal vein-constricted and sham-operated rats. Aortic rings from portal vein-constricted rats exhibited significantly impaired contractility to phenylephrine and potassium chloride compared with control rats. Preincubation with the nitric oxide synthase inhibitor nitro-L-arginine methyl ester significantly increased contractility to phenylephrine and potassium chloride in both portal-hypertensive and control tissues, with greater effect in the portal-hypertensive rings. Despite nitro-L-arginine methyl ester, maximal contractions were still significantly smaller in the portal-hypertensive tissues. Vascular relaxation evoked by acetylcholine, but not by the endothelium-independent vasodilator glyceryl trinitrate, was significantly impaired in the portal-hypertensive group. Our results demonstrate significant impairment in vascular function in aortic rings in this model of portal hypertension. The addition of a nitric oxide synthase inhibitor partly corrected these changes, suggesting that although nitric oxide is likely an important mediator, other factors may also be involved in the pathogenesis of these alterations in vascular function.

Acetylcholine↗
PubMed1994

Attenuation of acetaminophen hepatitis by prostaglandin E2. A histopathological study.

Acute acetaminophen hepatitis was produced in three groups of five rats given 1600 mg/kg by gavage. The protective effect of 16,16-dimethyl prostaglandin E2, 200 micrograms/kg administered subcutaneously 30 min later, was compared to the protective effect of N-acetylcysteine 1 g/kg similarly administered. All animals were killed at 24 hr, and liver tissues were compared histologically to the damage found in acetaminophen-treated controls and untreated anatomic controls. Serum transaminase values at 24 hr exceeded 1000 units in the acetaminophen control group, averaged 658 units in the acetylcysteine treated group, and were near normal (75 units) in the prostaglandin treated group (P < 0.02). Liver samples (1 cm3) were removed terminally at 24 hr. Liver damage was assessed without reference to precedent history. Histopathologically, damage was most severe in the acetaminophen control group, mainly in pericentral lobular zones. The prostaglandin-treated group showed considerably less damage, which was confined to the hepatic vein area. The acetylcysteine-treated group showed an intermediate degree of damage. We conclude that dmPGE2, given 30 min after ingestion of acetaminophen was found to be more effective in limiting liver damage than NAC in this rat model.

16,16-Dimethylprostaglandin E2↗
PubMed1994

Reversible jaundice in primary biliary cirrhosis due to hyperthyroidism.

A patient with primary biliary cirrhosis had a dramatic deterioration in liver function with jaundice over 2 months as a result of development of Graves' disease. Clinical examination and radiological and cardiovascular investigations excluded heart failure and biliary obstruction as the cause of this deterioration. The patient's jaundice entirely reversed with treatment of hyperthyroidism, with bilirubin levels decreasing from 244 to 16 mumol/L (14.35 to 0.94 mg/dL). Deterioration in liver function in a patient with primary biliary cirrhosis as a result of hyperthyroidism has not previously been described.

Bilirubin↗