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Biomedical subjects

N Sheron

Publications and source records attributed to N Sheron.

At least 37 records · Page 2Linked to original sources
PubMed1991

The use of interferon-alpha in virus infections.

The interferons (IFN) act too slowly to arrest acute viral infections, but interferon-alpha (IFN alpha) preparations have proved useful in some chronic infections and will clearly be used increasingly in these in the future. In the preparations derived from human leucocytes or cultured B lymphoblastoid cells, which are in routine clinical use, mixtures of a number of distinct subtypes of human IFN alpha have been identified. There are also 3 slightly different versions of the same single subtype, IFN alpha-2, made by recombinant DNA procedures in bacteria. IFN alpha preparations are injected intramuscularly or subcutaneously. Dose-related side effects are common but usually tolerable, but prolonged treatment may cause increasing fatigue and depression. Some patients form neutralising antibodies which block the effects of the IFN; these appear to be relatively more common after recombinant IFN alpha-2 than after IFN derived from human cells. Given intranasally, IFN alpha can prevent a subsequent experimental rhinovirus infection, or the spread of natural colds within a family. Repeated administration progressively damages the nasal mucosa, so that long term prophylaxis is not possible. IFN alpha has proved useful in patients with papillomavirus warts of the larynx, ano-genital region (condyloma acuminata) and skin (common warts). Treatment regimens remain to be optimised and are likely to include surgery or other treatments. IFN alpha and zidovudine (azidothymidine) synergistically inhibit the growth of HIV in vitro, and combination are on trial in patients with early AIDS. Very large doses of IFN alpha are effective against Kaposi's sarcoma in some AIDS patients. In chronic hepatitis B, continuing virus replication may lead to cirrhosis or primary liver cancer. Earlier clinical trials with IFN alpha gave inconclusive results, but recent large studies have confirmed that 25 to 40% of patients obtain benefit; this probably results from both the antiviral and the immunomodulatory effects of IFN alpha. In patients with chronic hepatitis C, the biochemical markers usually improve rapidly during IFN alpha administration, but relapse if treatment is stopped after only a few months; to increase the chances of sustained cure, the treatment period is now being prolonged.

HIV Infections↗
PubMed1991

Leukotriene and prostaglandin production after infusion of tumour necrosis factor in man.

Tumor necrosis factor-alpha is believed to be an important mediator of endotoxaemia and septic shock, the effects of which are thought to be mediated through the generation of cysteinyl-leukotrienes, thromboxane A2 and other prostanoids. We have investigated the production of these eicosanoids and also that of prostacyclin in vivo after infusion of tumor necrosis factor-alpha into 4 subjects with a chronic hepatitis B virus infection. This resulted in plasma TNF levels considerably greater than those observed in septic shock. Urinary excretion rate of leukotriene E4 increased by 2 to 3-fold in all subjects by 8 h following TNF infusion. Urinary excretion of thromboxane B2 and 6-oxo-prostaglandin F1 alpha, however, increased in the first 4 h in 3/4 subjects by 2 to 40-fold and returned towards baseline by 8 h. Excretion of the hepatic metabolite, 2,3-dinor 6-oxo-prostaglandin F1 alpha, increased in all subjects (2 to 4-fold at 4h). We conclude that there is increased production of cysteinyl leukotrienes, thromboxane A2 and prostacyclin after infusion of tumour necrosis factor into man.

Adult↗
PubMed1991

Interferon-alpha receptor expression and regulation in chronic hepatitis B virus infection.

Interferon-alpha elicits antiviral and immunoregulatory activities by binding to specific receptors on the cell surface. In this study, binding characteristics of interferon-alpha to peripheral blood mononuclear cells in patients with chronic hepatitis B virus infection were studied using radioiodinated recombinant interferon-alpha 2b to determine interferon-alpha receptor numbers and dissociation constants. A single class of interferon-alpha receptor was demonstrated on peripheral blood mononuclear cells and mononuclear subsets. Peripheral blood mononuclear cells from patients with chronic hepatitis B virus infection (n = 20) and controls (n = 16) expressed a similar number of interferon-alpha receptors (484 +/- 175 vs. 511 +/- 168 sites/cell respectively, p = NS) with a similar dissociation constant (dissociation constant approximately 0.2 to 0.7 nmol/L). Expression of interferon-alpha receptors was similar in monocyte-enriched and lymphocyte-enriched fractions in both groups. Similar changes were observed in patients receiving alpha-interferon therapy. There was no correlation between interferon-alpha receptors expression and serum transaminase, serum HBsAg, serum HBV DNA, liver histological findings or the response to interferon-alpha therapy. After incubation of lymphocytes in vitro with interferon-alpha 2b (10 to 1,000 U/ml), interferon-alpha receptors number dropped by 42% to 80%, but this was associated with an increase in binding affinity (dissociation constant approximately 0.05 to 0.15 nmol/L) in both patients and controls. There was significant delay in the initial phase of receptor recovery in the patients with chronic hepatitis B virus infection compared with normal controls (days 1 and 2, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Elevated plasma interleukin-6 and increased severity and mortality in alcoholic hepatitis.

Recent studies in alcoholic hepatitis have proposed a role for the cytokine tumour necrosis factor-alpha (TNF-alpha) a mediator of endotoxic shock in sepsis. In this study plasma levels of the closely related cytokine interleukin-6 (IL-6) were assayed in 96 samples from 58 patients with severe alcoholic hepatitis, and 69 patients in control groups (21 normal, 10 alcoholic without liver disease, 10 inactive alcoholic cirrhosis, 18 chronic liver disease, 10 chronic renal failure). Plasma IL-6 levels were markedly elevated in patients with alcoholic hepatitis when compared with all control groups (P less than 0.001). IL-6 levels were higher in patients who died (P = 0.04) and correlated with the features of severe disease including: increased grade of encephalopathy, increased neutrophil count, increased prothrombin ratio, hypotension, increased serum creatinine and increased serum bilirubin. Surprisingly, no correlation was found between levels of plasma IL-6 and plasma TNF-alpha or endotoxin, or the presence of infection; an inverse correlation was found between plasma IL-6 and serum globulins. These findings provide further evidence that the IL-6/TNF cytokine system is activated in severe alcoholic hepatitis and may mediate hepatic or extra-hepatic tissue damage.

Adult↗
PubMed1990

Increased plasma tumor necrosis factor in severe alcoholic hepatitis.

STUDY OBJECTIVE: To determine whether elevated tumor necrosis factor levels contribute to the clinical manifestations and complications of severe acute alcoholic hepatitis and to evaluate the relation between tumor necrosis factor and plasma levels of endotoxin and interleukin-1 beta. DESIGN: Prospective, controlled study. SETTING: The liver unit of a university teaching hospital. PATIENTS: We studied 21 patients with acute severe alcoholic hepatitis. There were four control groups: patients with inactive alcoholic cirrhosis, alcoholic persons without liver disease, patients with impaired renal function, and normal subjects. MEASUREMENTS AND MAIN RESULTS: With one exception, patients with alcoholic hepatitis had higher tumor necrosis factor levels (mean, 26.3 ng/L; 95% CI, 21.7 to 30.9) than normal subjects (6.4 ng/L; CI, 5.4 to 7.4). Patients who subsequently died had a higher tumor necrosis factor level (34.7 ng/L; CI, 27.8 to 41.6) than survivors (16.6 ng/L; CI, 14.0 to 19.2). In patients with alcoholic hepatitis, tumor necrosis factor levels correlated positively with serum bilirubin (r = 0.74; P = 0.0009) and serum creatinine (r = 0.81; P = 0.0003). Patients with alcoholic hepatitis had higher tumor necrosis factor levels than patients with inactive alcoholic cirrhosis (11.1 ng/L; CI, 8.9 to 13.3) and severely alcoholic persons without liver disease (6.4 ng/L; CI, 5.0 to 7.8). Patients with abnormal renal function had lower tumor necrosis factor levels (14.1 ng/L; CI, 5.4 to 22.8) than patients with alcoholic hepatitis. Serial samples obtained during a 1-week period from patients with alcoholic hepatitis showed no significant change in tumor necrosis factor when patients who died were compared with survivors. No correlation was found between tumor necrosis factor and plasma endotoxin. Levels of interleukin-1 beta did not exceed 20 ng/L. CONCLUSIONS: Elevations in tumor necrosis factor in alcoholic hepatitis are most marked in severe cases, suggesting that tumor necrosis factor plays a role in the pathogenesis.

Alcoholism↗
PubMed1990

Dose-dependent increase in plasma interleukin-6 after recombinant tumour necrosis factor infusion in humans.

Several studies have shown that the cytokine interleukin-6 (IL-6) is produced in response to tumour necrosis factor (TNF) in vitro. This study examines the in vivo relation between these two cytokines with assays of plasma IL-6 and TNF levels in subjects with chronic hepatitis B undergoing immunomodulatory therapy with recombinant TNF (rTNF). Plasma IL-6 was detected from 20 min after rTNF infusion with levels peaking after 2-3 h and levels correlated with the dose of rTNF administered (r = 0.67, P = 0.004). Peak levels of IL-6 (mean 295, range 266-297 ng/l) were lower than those seen in certain disease states despite the very high peak levels of rTNF (mean 11,750, range 5623-18,620 ng/l). These findings suggest that the very high levels of IL-6 found in certain disease states are not purely the result of circulating TNF. Other factors such as endotoxin or other cytokines may also play a role in determining levels of plasma IL-6.

Dose-Response Relationship, Drug↗
PubMed1989

Intestinal ischaemia associated with phaeochromocytoma.

The present case report describes a patient with an adrenal phaeochromocytoma who presented with infarction of the small intestine. The clinical features, diagnosis and treatment of this case are described. Despite excision of the tumour and necrotic intestine, this patient died in the postoperative period from overwhelming sepsis and multi-organ failure. Special reference is made to the delayed effects of established intestinal ischaemia on immune function and it is suggested that this was major contributory factor to the fatal outcome in the present case. The onset of gastro-intestinal symptoms in patients with phaeochromocytoma should suggest the possibility of imminent gut ischaemia and indicate the necessity for prompt excision of the tumour.

Adrenal Gland Neoplasms↗
PubMed1989

Sarcoidosis presenting with an acute Guillain-Barré syndrome.

A 28 year old Caucasian male presented with an acute Guillain-Barré syndrome and bilateral facial weakness. He had an abnormal chest radiograph. Lumbar puncture revealed acellular fluid with a raised protein count and lung function tests showed a restrictive ventilatory defect. The patient deteriorated and required mechanical ventilation for 14 days. Steroids and plasmapheresis were not used and the patient spontaneously recovered. Two months after presentation limb power was almost normal but there was residual partial bilateral facial weakness. The chest radiograph remained abnormal and repeat lung function tests showed a persistent restrictive ventilatory defect and a reduced gas transfer coefficient. A transbronchial biopsy revealed non-caseating granulomata. The association between neurosarcoidosis and Guillain-Barré polyneuropathy is discussed and the literature reviewed.

Acute Disease↗
PubMed1987

Temporary sequential atrioventricular pacing in myocardial infarction.

The loss of atrial contraction can seriously impair cardiac output when complete heart block follows myocardial infarction. We describe two cases in which temporary sequential atrioventricular pacing was lifesaving. The pacemaker used was a previously explanted internal pacemaker. By avoiding the need for an expensive dedicated temporary pacemaker this technique may be more widely applied.

Cardiac Pacing, Artificial↗