Search PubMed⌕ Search

Biomedical subjects

D C Barber

Publications and source records attributed to D C Barber.

At least 91 records · Page 5Linked to original sources
PubMed1983

An objective feature extraction technique applied to the Doppler waveforms from the groin: a prospective study.

A group of 80 patients presenting with lower limb ischaemia were classified according to their arteriographic findings. The maximum frequency envelope from the Doppler waveforms obtained from the common femoral artery were retrospectively analysed using a mathematical feature extraction technique, principal component analysis (PCA). Two of the three coefficients uniquely describing each waveform were plotted and classified according to their arteriographic groupings. The best separating planes were then defined. Twenty-eight new patients were subsequently prospectively assessed using the principal components and separating planes defined in the previous study. The results were compared with the arteriographic findings and showed that PCA represents a significant improvement in diagnostic accuracy when compared with other techniques.

Aorta↗
PubMed1983

Effect of gastrointestinal intubation on the passage of a solid meal through the stomach and small intestine in humans.

The effect of a gastrointestinal tube on the passage of a radiolabeled solid meal through the stomach and small intestine was investigated in 22 healthy volunteers using the gamma camera and breath hydrogen analysis. Gastric emptying was significantly retarded in 12 subjects, who had an intestinal tube in situ compared with 10 control subjects, who were not intubated (t 1/2 = 1.5 +/- 0.1 vs. 1.2 +/- 0.1 h; p less than 0.02). On the other hand, colonic filling was significantly accelerated in the intubated subjects (onset: 1.2 +/- 0.2 vs. 2.9 +/- 0.4 h; p less than 0.001; t 1/2: 4.1 +/- 0.3 vs. 5.6 +/- 0.5 h; p less than 0.001). Values for small bowel residence were significantly reduced in the intubated subjects (5.3 +/- 0.5 vs. 6.5 +/- 0.6 food hours; p less than 0.001). Paired studies, carried out in an additional 11 normal subjects, confirmed that small bowel transit time was significantly shortened during intestinal intubation in the same individuals (2.0 +/- 0.3 vs. 3.6 +/- 0.4 h). These results suggest that intubating the gastrointestinal tract may profoundly affect its function.

Adult↗
PubMed1982

Effects of loperamide on anal sphincter function in patients complaining of chronic diarrhea with fecal incontinence and urgency.

We have investigated the effect of loperamide (4 mg tds) on the continence to a standard volume of rectally infused saline and anorectal manometry in 26 patients complaining of chronic diarrhea complicated by fecal incontinence and severe urgency. Each patient was treated for one week with loperamide (4 mg tds) and for one week with an identical placebo in a double-blind cross-over trial. Our results showed that as well as its established effects of improving stool consistency and reducing stool weight, frequency and episodes of incontinence and severe urgency, loperamide also significantly improved continence to a standard volume of rectally infused saline. This action was associated with an increase in the maximum basal sphincter pressure, an increase in the rectal volume required to abolish recovery of the rectoanal inhibitory reflex, and a reduction in rectal compliance. These results suggest that loperamide may have a specific action on the anal sphincter, which may aid continence in patients who complain of diarrhea and fecal incontinence.

Adult↗
PubMed1981

FIRST AID: a design philosophy and a program for on-line symptom processing.

A major problem for computer-aided diagnosis systems, particularly those designed for on-line use in clinical settings, is that their operation may be obtrusive or unacceptable within established clinical routine. Criteria for a general approach to the design of the on-line aids in clinical decision-making are presented. An interpreter is described that is designed to be broadly applicable within the area of statistical diagnosis, but which is also designed to encourage the development of congenial clinical systems. The use of the program and its features are illustrated by an application in the diagnosis of 'dyspepsia'.

Computers↗
PubMed1980

The use of principal components in the quantitative analysis of gamma camera dynamic studies.

The reduction of the enormous quantity of data in a radionuclide dynamic study to a few diagnostic parameters presents a problem. Conventional methods of data reduction using regions-of-interest or functional images have several defects which potentially limit their usefulness. Using a principal components analysis of the elemental curves representing the change of activity with time in each pixel, followed by a further factor analysis, it is possible to extract the fundamental functional changes of activity which underly the observed variation of activity. An example of this analysis on a dynamic brain scan suggests that the three fundamental phases of activity represent activity in the arterial system, the venous system and diffusion of tracer into the tissues.

Brain↗
PubMed1980

The effect of beta-adrenoceptor agonists and antagonists on gastric emptying in man.

1. The effect of beta-adrenoceptor agonists and antagonists on gastric emptying of a solid meal labelled with Indium113m was measured by a gamma camera in healthy volunteers or patients with hypertension. Each subject acted as his own control. 2 In ten subjects given isoprenaline (10 or 20 mg) sublingually 30 min before the meal, gastric emptying half-times were significantly prolonged (P less than 0.05). No effect was observed when isoprenaline was given immediately before the meal. 3 Salbutamol, 4 mg four times daily for 1 week also significantly prolonged gastric emptying in four subjects (P less than 0.05). 4 The effect of isoprenaline on gastric emptying was blocked by propranolol 40 mg four times daily for 1 week. 5 In ten subjects propranolol 40 mg four times daily alone for 1 week was found to significantly speed up gastric emptying (P less than 0.005), suggesting that emptying of the normal stomach is subject to some degree of adrenergic inhibition.

Adrenergic beta-Agonists↗
PubMed1977

Unstirred layer and kinetics of electrogenic glucose absorption in the human jejunum in situ.

Using an electrical technique we estimated the thickness of the unstirred layer in the human jejunum during kinetic studies of electrogenic glucose absorption. The unstirred layer in seven healthy volunteers (632 +/- 24 mum: mean +/- SEM) was significantly thicker than in 10 patients with active coeliac disease (442 +/- 23 mum) but not significantly different in seven patients who had responded to treatment by gluten withdrawal (585 +/- 49 mum). There were similar differences in the values of ;Apparent Km' for electrogenic glucose absorption between healthy control subjects (36 +/- 6 mM) active coeliac patients (11 +/- 1 mM) and treated coeliac patients (31 +/- 5 mM). The changes in PDmax however, showed a different pattern. The PDmax in the active coeliac group (6.8 +/- 0.7 mV) was lower than in controls (7.6 +/- 0.6 mV) but not significantly so, while the PDmax in the treated coeliac group (10.6 +/- 0.9 mV) was significantly higher than in both the active coeliac and control groups. It should be noted that both operational kinetic parameters obtained in the present study are much lower than those obtained previously (Read et al., 1976b) because of the use of siphonage. Analysis of the results using a computer simulation indicates that the reduction in Apparent Km in active coeliac disease can be caused by the interaction of the decreased maximal absorption rate for glucose (Jmax) with the attenuated unstirred layer. In these circumstances it is not necessary to postulate any change in the affinity of the transport mechanism for glucose (;Real Km'). It is remarkable that the disease process produces an Apparent Km which is much closer to the Real Km than that found in health.

Celiac Disease↗
PubMed1976

Gastric emptying of solid meals in diabetics.

The gastric emptying rate of an isotopically labelled solid meal was compared in 29 insulin-dependent well-controlled diabetics and 18 normal controls. The diabetics were assessed for evidence of autonomic neuropathy. No significant difference in gastric emptying rate was found between controls and diabetics with or without autonomic neuropathy. Only three diabetics had greatly delayed gastric emptying, but in one of these the test had given a normal result on an earlier occasion.

Adult↗
PubMed1976

Digital computer processing of brain scans using principal components.

Most of the scan processing methods used to date are unable to distinguish between normal and abnormal features. This paper describes a method of constructing a particular orthogonal transform from a set of normal images, the method of principal components, which may be used selectively to filter out normal features, leaving behind abnormal features. The method has been applied to brain scans and has been implemented on a small digital computer system with magnetic disc.

Brain Diseases↗
PubMed1976

Gastric emptying in control subjects and patients with duodenal ulcer before and after vagotomy.

The emptying of a solid meal labelled with Indium 113mDTPA from the stomach was studied with a gamma camera in 26 normal subjects, 27 patients with duodenal ulcer, on 41 occasions after truncal vagotomy and pyloroplasty and 38 times after highly selective vagotomy. Applying the method of principal component analysis to the results, differences were detected between control and duodenal ulcer subjects and two probable subgroups of duodenal ulcer were observed. Half emptying times did not reveal these patterns. After vagotomy, delayed emptying was general at one week. At one month, patients after highly selective vagotomy had a more normal result than those with truncal vagotomy and pyloroplasty (TV), but by six months no significant difference in overall emptying rate was found, although changes in the pattern of gastric emptying persisted in some patients after TV.

Adult↗