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Biomedical subjects

M P Jones

Publications and source records attributed to M P Jones.

At least 19 recordsLinked to original sources
PubMed1992

Cigarette smoking and nicotine delay postprandial mouth-cecum transit time.

The acute effects of both cigarette smoking and nicotine on postprandial mouth-cecum transit were studied in 20 habitual smokers, 10 males and 10 females. Mouth-cecum transit time was measured by the breath hydrogen technique, following ingestion of a standard mixed liquid meal. Each subject was studied on four separate occasions, either (1) sham or actively smoking two standard cigarettes, commencing 20 min after the meal, or (2) chewing two placebo or nicotine tablets over a 60-min period, commencing immediately after the meal. The time of administration of these stimuli was designed to minimize the effects on mouth-cecum transit time of alterations in gastric emptying. Mouth-cecum transit time was prolonged in response to both smoking [median and interquartile range: 120 (95, 150) min vs 100 (75, 140) min, P = 0.01] and nicotine [120 (80, 170) min vs 100 (70, 140) min, P = 0.002]. No difference was observed between sexes with respect to nicotine; the effect of smoking on mouth-cecum transit time, however, was less pronounced in females compared to males [difference active-placebo: 10 (10, 20) min vs 35 (20, 60) min, P = 0.01]. We conclude that acute cigarette smoking delays mouth-cecum transit time, an effect most likely due to nicotine.

Adult↗
PubMed1992

Suppression of anger and gastric emptying in patients with functional dyspepsia.

Psychologic distress and gastric motor dysfunction have both been implicated in the pathogenesis of functional (non-ulcer) dyspepsia (FD). This study assesses the association between psychologic factors and gastric emptying in 28 FD patients. Subjects completed an extensive range of psychologic questionnaires and underwent dual-isotope scintigraphic assessment of solid and liquid gastric emptying. Attempts to resist, control, suppress, and hold in anger, to adopt a fighting spirit whilst dealing with chronic stressors, and manifest unhappiness were predictors of prolonged gastric emptying. These findings suggest that psychologic factors may be important in the aetiology of gastric stasis and subsequent upper gastrointestinal symptoms in patients with functional dyspepsia.

Adaptation, Psychological↗
PubMed1992

Symptom provocation in irritable bowel syndrome. Effects of differing doses of fructose-sorbitol.

The role of fructose and sorbitol, when ingested together, in the aetiology of irritable bowel syndrome (IBS) is controversial. The aims of this study in IBS patients, therefore, were to compare differences in symptom provocation with various doses of fructose-sorbitol and to relate differences in the extent of colonic hydrogen production after each dose to such symptom provocation. Two different mixtures of fructose and sorbitol--20 g fructose plus 3.5 g sorbitol ('lower' dose) and 25 g fructose plus 5 g sorbitol ('higher' dose)--were administered to 15 patients with IBS and to 24 healthy controls. Breath hydrogen concentrations were determined at 10-min intervals for 3 h after ingestion of each mixture, and the presence and severity of a range of gastrointestinal symptoms were recorded on a standard form before, during, and after the study. Total symptom score in IBS patients, but not controls, was greater (p < 0.05) after the higher than after the lower dose of fructose-sorbitol mixture, and, for the higher dose, symptoms were significantly greater in IBS patients than in controls (p < 0.05). Moreover, the increase in total symptom score between the higher and lower dose mixtures was of a greater magnitude (p = 0.01) in IBS patients than in controls. No significant correlation was observed between the increase in symptom score and the increase in peak hydrogen concentration or the increase in integrated hydrogen response between lower and higher dose mixtures, although these latter increases were at times substantial.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Effects of acute psychologic stress on small-intestinal motility in health and the irritable bowel syndrome.

Psychologic stress may be a provoking factor in the alterations in phase-2 motor activity of the migrating motor complex (MMC) which have been recorded in patients with the irritable bowel syndrome (IBS). To test this, changes in phase-2 duodenojejunal motor activity during 20 min of psychologic stress in 10 patients with IBS were compared with those shown by 10 healthy subjects. Autonomic arousal in response to the stressor was assessed by cardiovascular responses and self-reported levels of anxiety and tension. IBS and controls showed a significant cardiovascular and subjective response to stress which was comparable in the two groups. In general, duodenal phase-2 motor activity was suppressed during stress in both IBS and controls. Jejunal motor activity showed a similar inhibitory response in both groups, but the change in motility index was significant for controls only. Qualitatively, stress did not cause clustered contractions in either the IBS or the control group. However, in IBS patients with clustered contractions in the basal period there was inhibition of this pattern during stress. These findings suggest that acute psychologic stress profoundly suppresses, rather than enhances, duodenojejunal MMC phase-2 motility in healthy subjects. IBS patients, irrespective of their underlying phase-2 motor pattern show similar, although less marked, changes in motility.

Adult↗
PubMed1991

Prolonged QT interval and risk of sudden death in South-East Asian men.

Sudden death in sleep occurs in substantial numbers among young men in South-East Asia. The frequencies of electrocardiographic abnormalities were measured in groups with varying risks of such sudden death. The mean heart-rate-corrected QT interval (QTc) was significantly (p less than 0.05) greater among 123 Laotian refugees in Thailand at high risk (405 [95% confidence interval 397-413] ms) than in 77 Laotian refugees in the United States at lower risk (364 [359-369] ms) and 199 non-Asian US residents at negligible risk (358 [354-362] ms). Among refugees in Thailand, prolonged QTc interval was associated with poor thiamine status and a history of seizure-like episodes in sleep. Thiamine deficiency may be a cause of prolonged QT interval and sudden death in this region.

Adolescent↗
PubMed1991

Cancer registry problems in classifying invasive bladder cancer.

A slide review of diagnostic pathologic tissue obtained from 364 bladder cancer cases, identified through the Iowa Surveillance, Epidemiology, and End Results (SEER) Program in 1983, classified 97 (26.6%) of these cases as invasive bladder cancers. These findings contrasted sharply with the Iowa SEER Program classification that coded 289 (79.4%) of these cases as invasive bladder cancers. These results were validated further by the hazard ratio of 4.54 (95% confidence interval, 2.57 to 8.03) among invasive relative to noninvasive bladder cancer cases when the slide review findings were used. In contrast, the hazard ratio was only 1.70 (95% confidence interval, 0.76 to 3.79) when the Iowa SEER Program findings were used. The traditional method used by the National Cancer Institute's SEER Program to deal with this problem is described and its implications are discussed.

Humans↗
PubMed1991

Enhanced perception of physiological intestinal motility in the irritable bowel syndrome.

An increased awareness of intestinal distention or contraction is implicated in the pathogenesis of the irritable bowel syndrome. This study aimed to test this hypothesis in 20 patients with the irritable bowel syndrome and 10 controls by relating the reporting of abdominal sensations to the occurrence of the duodenal phase 3 activity front of the migrating motor complex. During prolonged recordings of interdigestive small bowel motility, subjects were asked to report any episodes of abdominal sensation they experienced. Diurnally, the rate of occurrence of abdominal sensation was significantly greater in patients with the irritable bowel syndrome than in controls (P less than 0.001); such episodes were coincident with a duodenal activity front in 9 patients with the irritable bowel syndrome and in 1 control (P less than .05). Moreover, the rate of occurrence of episodes of sensation was greater (P less than 0.01) during diurnal phase 3 activity than during diurnal phase 2 activity. When episodes were coincident with duodenal phase 3 activity, these activity fronts were of significantly greater amplitude (irritable bowel syndrome: median, 23 mm Hg) than "noncoincident" activity fronts (median, 17 mm Hg; P less than 0.05) in both patients and controls. These data strongly suggest that certain physiological small bowel motor events, if of sufficient contraction amplitude, are able to be perceived by a greater proportion of irritable bowel syndrome patients and with greater frequency than by healthy subjects. The authors conclude that the threshold for perception of intestinal contraction is lower than normal in at least some patients with the irritable bowel syndrome.

Abdomen↗
PubMed1991

Response of pre-adult and adult stages of Trichuris muris to common anthelmintics in mice.

The common anthelmintics, oxantel, mebendazole, albendazole and pyrantel were assessed for their comparative activity against Trichuris muris in mice. Mice were infected with T. muris and the infection was maintained by a brief cortisone administration during the second week of infection. Mice carrying the infection with different life cycle stages, viz. fourth stage larvae (L4), pre-adult and adult stages were dosed with anthelminitics. The worm burdens in control infection groups varied although infection dose and other conditions were uniformly followed. With various dose regimens tested, oxantel was highly potent; it eliminated completely pre-adult and adult stages, respectively at 25 and 12.5 mg kg-1 dose levels with significant activity also against adult worms at a 1.56 mg kg-1 dose level and against pre-adults at a 6.25 mg kg-1 level. Pre-adults required twice the dose given to that of adults for complete (100%) activity. Mebendazole was the next most active; a dosage of 37.5 mg kg-1 was completely active against pre-adults whereas a dosage of 2 x 50 mg kg-1 was required for complete elimination of adult worms. In addition, about 90% of the worms were eliminated with a single dose of 150 mg kg-1. However, a significant activity was seen against adults at a 25 mg kg-1 level and pre-adults at 37.5 mg kg-1, the lowest level tested. In comparison, albendazole did not induce complete clearance of pre-adult and adult stages even when tested at dose levels as high as 150 and 2 x 75 mg kg-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Albendazole↗
PubMed1991

Determinants of recurrent ischaemia and revascularisation procedures after thrombolysis with recombinant tissue plasminogen activator in primary coronary occlusion.

This paper reports the immediate effects of thrombolysis and their subsequent influence on revascularisation procedures and clinical outcome over the subsequent twelve months. Coronary arteriography was performed at 21 days on 131 of 145 patients who received recombinant tissue plasminogen activator (n = 68) or placebo (n = 63) within 2.5 hours of symptom onset after primary coronary occlusion. Patency rates (TIMI grades 2 and 3) of the infarct-related artery were 81% with plasminogen activator and 63% with placebo (P = 0.02). Early (within 21 days) angiography for recurrent ischaemia was necessary in 31 (21%) patients (20 plasminogen activator, 11 placebo NS) and definite reinfarction occurred in 8 (5%) patients (4 plasminogen activator, 4 placebo). During one year follow-up without planned secondary intervention, coronary artery bypass grafting was more frequent in patients who had received thrombolytic therapy (23% plasminogen activator, 4% placebo P = 0.001); coronary angioplasty procedures were similar in both groups (12% plasminogen activator, 11% placebo NS). Mortality at 21 days was 5% (4 plasminogen activator, 4 placebo) and at one year was 7% (5 plasminogen activator, 5 placebo). Logistic regression analysis identified models comprising characteristics predictive of subsequent bypass grafting (plasminogen activator, multivessel disease, occluded infarct-related artery) and coronary angioplasty (non-q wave infarction, severe (91-99%) residual stenosis, left anterior descending infarct-related artery). Initial non-q wave infarction was the only predictor of early recurrent ischemia (odds ratio 4, P = 0.02) irrespective of residual stenosis severity.

Angioplasty, Balloon, Coronary↗
PubMed1991

Medulloblastoma: a population-based study of 532 cases.

Five hundred thirty-two cases of medulloblastoma (males n = 327 and females n = 205), aged 0 to 86 years diagnosed between 1973 and 1986 were studied to determine the incidence in different geographic regions of the United States and to evaluate the effect of various factors on survival. The median age was 9 years and average follow-up time was 45 months. The overall incidence rate was 1.8 per one million person-years. Variables that were statistically significant (p less than 0.05) in a multivariate model determining survival in rank order were treatment group, sex, geographic region, year group and age. This observational study found that 1) age and sex were statistically significant factors in describing the incidence rates, whereas year group and geographic region were not; 2) no incidence peak in the third decade of life was observed; 3) a significant improvement in survival was observed in the combined 1978 to 1986 year groups relative to the 1973 to 1977 year group; 4) the overall 5-year survival probability was 45%; and 5) there has been an increase over time in the use of more than two modalities of treatment.

Adolescent↗
PubMed1991

Ischemic cerebrovascular complications and risk factors in idiopathic hypertrophic subaortic stenosis.

To determine the risk and time to cerebrovascular complications with idiopathic hypertrophic subaortic stenosis, we studied 119 patients (66 men and 53 women) with evidence of this disease based on strict echocardiographic criteria and followed them up for a mean +/- SEM of 6.5 +/- 0.6 years. Cerebral ischemic events occurred in 26 patients (22%), and in five patients stroke was the initial presenting event. Men had cardiac symptoms at a younger age than women, but there was no significant difference in age at the time of stroke. Cardioembolic cerebrovascular events were associated with atrial fibrillation and left atrial enlargement, whereas atheroembolic events were associated with hypertension. An increased risk of stroke was associated with female sex, mitral anulus calcification, hypertension, and atrioventricular conduction delay. Unlike most previous series, this study shows that patients with idiopathic hypertrophic subaortic stenosis may present with stroke.

Adult↗
PubMed1991

Chronic diarrhea in essential mixed cryoglobulinemia: a manifestation of visceral vasculitis?

Gastrointestinal involvement occurs frequently in essential mixed cryoglobulinemia, and most often involves the liver and spleen. Intestinal involvement is much less common and is generally felt to be a late and often catastrophic manifestation of the disease due to severe vasculitis. Occasionally, the disorder mimics inflammatory bowel disease, both clinically and radiographically. We recently cared for a patient with essential mixed cryoglobulinemia who developed persistent diarrhea. Endoscopic evaluation revealed scattered petechial lesions in the duodenum and colon as well as prominent lymphoid hyperplasia in the terminal ileum. Mucosal biopsies disclosed the presence of diffuse inflammation. We suggest that this patient's diarrhea was due to intestinal vasculitis and that prominent ileal lymphoid hyperplasia may be a manifestation of essential mixed cryoglobulinemia.

Chronic Disease↗
PubMed1990

Cigarette smoking. A risk factor for cerebral infarction in young adults.

To assess the impact of cigarette smoking on stroke in young adults (15 to 45 years old), we compared smoking data from 181 patients with cerebral infarction with that of 307 control subjects matched for age, gender, geographic location, and hospital admission dates. While controlling for these matching variables and hypertension, an analysis based on a conditional logistic regression model indicated that a smoker was 1.6 times more likely to have a cerebral infarction than a non-smoker (95% confidence interval, 1.07 to 2.42). There was a cumulative dose effect with each additional pack-year causing a greater risk of having a cerebral infarction. In fact, after adjusting for all other risk factors, there was a significant quadratic component to the dose-response relationships, with the result that individuals with a larger number of pack-years were invariably the stroke patients. There was no significant difference in smoking status among the various subtypes of cerebral infarction (atherosclerotic, nonatherosclerotic vasculopathy, cardioembolic, hematologic related, undetermined). These data indicate that cigarette smoking is an important risk factor for cerebral infarction in young adults. Risk factor modification through cessation of smoking may reduce the risk of ischemic stroke in young adults.

Adolescent↗
PubMed1990

Statistical analysis of K 2 x 2 tables: a comparative study of estimators/test statistics for association and homogeneity.

In order to control for confounding variables, epidemiologists often obtain data in the form of a 2 x 2 table. One variable is usually the disease status, while the other variable represents a dichotomous exposure variable that is suspected of being a risk factor. If a confounding variable is present, the data are often stratified into several 2 x 2 tables. The objectives of the analysis are to test for the association between the suspected risk factor and the disease and to estimate the strength of this relationship. Before estimating a common odds ratio, it is important to check whether the odds ratios are homogeneous. This paper presents the results of a Monte Carlo study that was performed to determine the size and power of a number of tests of association and homogeneity when the data are sparse. We also evaluated the performance of three estimators of the common odds ratio. For the Monte Carlo studies, equal numbers of cases and controls were used in a wide variety of sparse data situations. On the basis of these studies, we recommend the Breslow-Day test for nonsparse data, and the T4 and T5 statistics for sparse data to test for homogeneity. The Mantel-Haenszel test of association is recommended for sparse and nonsparse data sets. With sparse data, none of the odds ratio estimators are entirely satisfactory.

Case-Control Studies↗
PubMed1979

Human biochemical response to ozone and vitamin E.

To determine whether vitamin E (dl-alpha-tocopherol) supplementation of the diet provides protection from inhaled oxidants such as ozone (O3) in community air pollution, its effects were studied in healthy adult volunteers, Experimental groups received 800 or 1600 IU of vitamin E for 9 wk or more; control groups received placebos. Double-blind conditions were maintained throughout the study. Biochemical parameters studied included red blood cell fragility; hematocrit and hemoglobin values; red cell glutathione concentration; and the enzymes acetylcholinesterase, glucose-6-phosphate dehydrogenase, and lactic acid dehydrogenase. No significant differences between the responses of the supplemented and placebo groups to a controlled O3 exposure (0.5 ppm for 2 h) were found for any of these parameters. The results indicate that vitamin E supplementation in humans, at the levels employed in this experiment, gives no added protection against blood biochemical effects of O3 in intermittently exercising subjects under exposure conditoins simulating summer ambient air pollution episodes.

Female↗
PubMed1979

Taxonomic and serologic studies on Micropolyspora faeni and Micropolyspora strains from soil bearing the specific epithet rectivirgula.

The results of serological studies on six strains of Micropolyspora faeni from hay, sputum and plant debris, and five strains of Mip. rectivirgula from soil indicated no significant differences between the two species. Antisera raised in rabbits against purified antigens of the type strains were used to compare the 11 strains by immunoelectrophoresis. The detailed antigenic composition of the type strains was also determined by two-dimensional immunoelectrophoresis against specific rabbit antisera and pooled serum samples from patients suffering from farmer's lung. Cross-reacting antigens were identified by intermediate gel immunoelectrophoresis. The close similarity of the two species was confirmed by the results of 60 morphological physiological and biochemical tests applied to the 11 strains. We consider that the strains belong to a single species and propose that the specific epithet faeni be conserved for the taxon.

Antigens, Bacterial↗