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Biomedical subjects

A McIntyre

Publications and source records attributed to A McIntyre.

33 records · Page 2Linked to original sources
PubMed1992

Isolated hepatitis B core antibody--can response to hepatitis B vaccine help elucidate the cause?

The finding of a positive hepatitis B core antibody (anti-HBc) in the absence of hepatitis B surface antigen (HBsAg) or hepatitis B surface antibody (anti-HBs) is relatively uncommon. This finding is known to occur during the 'window period' of acute hepatitis B between loss of HBsAg and the appearance of anti-HBs. It may also occur with active infection or following resolution. The aim of this study was to determine if response to hepatitis B vaccination would allow the separation of these subgroups of patients with isolated anti-HBc. Seventeen patients with persistent isolated core antibody were vaccinated and serum obtained at 2, 4 and 8 weeks. Results were compared with a seronegative control group. Six subjects (35%) but no control patients (p = 0.016) responded with a titre of greater than 50mIU/mL at two weeks, suggesting an anamnestic response due to prior infection and immunity. A further seven subjects (41%) finally seroconverted (anti-HBs titre greater than 10mIU/mL) thus excluding chronic infection and suggesting initial false positive results. Only two subjects did not respond to a full course of vaccination, but neither they nor any other subjects were positive for HBV DNA. These results indicate that hepatitis B vaccination and subsequent measurement of anti-HBs will identify evidence of past infection in the form of an anamnestic response in up to one third of the patients and will also exclude chronic infection on the grounds of a normal vaccine response in a majority of the remainder.

Adult↗
PubMed1991

Different fibers have different regional effects on luminal contents of rat colon.

The purpose of this study was to compare the effects of two highly fermentable fibers (oat brain and guar gum) with those of a less fermentable fiber (wheat bran) on the luminal environment of the large bowel. Rats were fed one of four diets containing either low fiber (2%), a highly fermented fiber (guar, 10%, or oat bran, 10%), or a medium fermented fiber (wheat bran, 10%). Short-chain fatty acids and pH showed a falling gradient along the large bowel with the low fiber, guar, and oat bran diets. However, wheat bran maintained total short-chain fatty acid levels in fresh feces at three times the levels seen with the other diets; both fecal butyrate concentrations and pH were maintained at cecal values in the distal large bowel. Thus, dietary fibers have differing effects on different regions of the luminal environment depending on their fermentability; it appears that slowly fermented fibers have a greater influence on the distal environment. Because butyrate is implicated as having an antitumor action, the variable effects of dietary fiber on tumorigenesis might be accounted for by its ability to influence distal large bowel butyrate concentrations.

Analysis of Variance↗
PubMed1990

Hypovolaemia can potentiate hypoglycaemic stress-induced adrenaline release in the anaesthetized rat.

The interaction between hypoglycaemic stress and hypovolaemic stress in promoting adrenaline secretion from the adrenal medulla has been studied in anaesthetised and conscious rats. In anaesthetized rats, insulin (1 IU/kg, i.v.) markedly increased plasma adrenaline concentrations whereas blood sampling alone did not. The hypoglycaemic response to insulin was greatly reduced if donor blood was used instead of saline to replace the withdrawn blood. The hypoglycaemic response was abolished by captopril or saralasin. The results suggest that adrenaline secretion in response to hypoglycaemic stress in anaesthetized rats is potentiated by hypovolaemic activation of the renin-angiotensin system. In contrast, in fully conscious rats, the response to hypoglycaemia was not abolished by captopril, indicating that in the absence of barbiturate anaesthesia, the hypoglycaemic release of catecholamines is not potentiated by the renin-angiotensin system.

Adrenal Medulla↗
PubMed1990

Spontaneous intramural rupture of the oesophagus.

The clinical, endoscopic, and radiological features of seven patients with an uncommon oesophageal injury characterised by long lacerations of the oesophageal mucosa with haematoma formation but without perforation are reported. The injuries were not related to forceful vomiting or any other definable cause but were similar to those previously described as intramural oesophageal rupture. Upper gastrointestinal endoscopy undertaken to identify the cause of haematemesis in six patients proved safe and useful. When dysphagia and odynophagia occurred early in the clinical course to alert the clinician to possible oesophageal injury, radiological contrast studies were used to exclude perforation. One patient in this study had oesophageal cavernocapillary haemangiomatosis which may have caused intramural oesophageal bleeding and submucosal dissection but in the remainder the aetiology of intramural oesophageal rupture remains uncertain. Conservative management was successful in all patients.

Aged↗
PubMed1989

Chorioretinal scarring following the Faden operation. A retrospective study of 100 procedures.

Following reports of a high incidence of chorioretinal scarring related to the Faden Procedure, a retrospective study was carried out at Moorfields Eye Hospital. One hundred unselected Faden procedures were followed up with orthoptic and fundoscopic examination. Our indications and technique for performing this operation are described. A 7% incidence of chorioretinal scarring was noted; this compares well with previously published figures for conventional squint surgery and this operation should therefore be considered safe.

Adolescent↗
PubMed1988

Effect of codeine and loperamide on upper intestinal transit and absorption in normal subjects and patients with postvagotomy diarrhoea.

Patients with chronic severe diarrhoea after truncal vagotomy and pyloroplasty are often difficult to treat using conventional antidiarrhoeal drugs and remain severely disabled. We examined the effect of two drugs, codeine phosphate and loperamide, on upper intestinal transit and carbohydrate absorption, measured non-invasively by serial exhaled breath hydrogen monitoring, in patients with postvagotomy diarrhoea who had previously failed to gain relief from drug therapy. Orocaecal transit was consistently faster in these patients than a group of controls and was associated with malabsorption of glucose. Codeine phosphate 60 mg significantly delayed transit in patients and controls and was associated with a reduction in glucose malabsorption and improvement in symptoms. Loperamide also delayed transit and improved symptoms, but the doses required for this effect (12-24 mg) were higher than usually considered necessary in secretory diarrhoea. These studies indicate that rapid intestinal nutrient transit and associated malabsorption is a factor in the development of diarrhoea postvagotomy and that symptomatic relief can be achieved in most patients by more rational use of existing drugs.

Adult↗
PubMedDate not supplied

Dietary modulation of colonic mucosal urokinase activity in rats.

The amount and type of dietary fibre ingested influences colonic luminal characteristics, especially the concentration of carbohydrate fermentation products such as butyrate. This study aimed to assess whether diets supplemented with fibres of differing fermentability (delivering different amounts of butyrate to the colon) influence mucosal activities of urokinase and brush border hydrolases, and epithelial turnover. Groups of five rats were fed one of four diets containing low (2%), highly fermented (guar 10% or oat bran 10%) or slowly fermented fibre (wheat bran 10%) for 4 weeks. Activities of urokinase, alkaline phosphatase, dipeptidyl peptidase IV and maltase were measured in mucosal homogenates of proximal and distal colon and from rectum. Proliferative kinetics were assessed in distal and proximal colon by the metaphase arrest technique. Hydrolase activities were similar across all four dietary groups but a significant difference was found for urokinase (P = 0.014). This was due to a reduction in urokinase activities of > 30% at the three sites in the wheat bran group compared with the other groups. Of proliferative indices, only crypt column height differed across the groups (P = 0.038) and was highest in rats fed wheat bran and lowest in those fed the low fibre diet (P = 0.047). The proportion of mitoses in the top one-fifth of the crypt also differed across groups (P = 0.038) due to the high values in the distal colon of the low fibre group. Thus, addition of a slowly fermented (but not highly fermented) fibre to the diet of rats reduces net urokinase activity in large bowel mucosa and increases the life span of colonic epithelial cells without changing activities of brush border hydrolases.

Alkaline Phosphatase↗