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Biomedical subjects

J Barrett

Publications and source records attributed to J Barrett.

At least 307 records · Page 17Linked to original sources
PubMed1984

The anaerobic end-products of helminths.

Parasitic helminths belong to 3 separate phyla and there is always the danger of over-generalization. The various routes of anaerobic carbohydrate breakdown in parasitic helminths differ in their efficiencies and in their power output. The choice of end-product represents a compromise between these two conflicting forces. In addition, anaerobic pathways must satisfy the redox requirements of the tissues and provide a source of intermediates for synthetic reactions. Other considerations include the metabolic cost of excretion and the effect of end-products on protein structure and function. The different end-products may fulfil additional functions such as pH control, nitrogenous excretion, osmotic regulation, intracellular signalling and the suppression of host responses. A complicating factor in parasitic helminths is the existence of strains with different biochemical characteristics, including marked variation in end-product formation. The various tissues of the same parasite can also produce different end-products and the pattern of end-product formation is influenced by a variety of extrinsic and intrinsic factors such as age, sex, length of incubation, pO2 and availability of substrates. The catabolic pathways of helminths thus show considerable functional adaptation. There is, as yet, no satisfactory explanation as to why helminths do not make the maximum use of any oxygen available to them; and the contribution of oxidative processes to the overall energy balance of parasites probably varies from species to species. The catabolic pathways of adult helminths are derived from the anaerobic pathways present in their free-living relatives. Two main trends are evident, homolactic fermentation and carbon dioxide fixation, the latter involving a partial reverse tricarboxylic acid cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1984

Incidence of lung cancer by cell type: a population-based study in New Hampshire and Vermont.

Identified were 1,906 cases of confirmed lung cancer that occurred among all residents of New Hampshire and Vermont over a 4-year period. Medical records, pathologists' reports, and, when possible, pathology slides were obtained and reviewed to assign cases to a specific histologic diagnosis. The diagnosis made by the original pathologist was generally confirmed upon review, except for the large cell undifferentiated cell type which appeared to be an unreliable classification. Among men at all ages incidence rates for squamous cell cancer far exceeded those for adenocarcinoma and small cell undifferentiated carcinoma, and the three age-incidence curves showed a similar pattern, rising until the eighth decade of life and then declining. Among women these three major cell types occurred about equally often, but the age-incidence curves differed in shape with adenocarcinoma reaching a peak incidence at an earlier age.

Adenocarcinoma↗
PubMed1984

Medium resolution computergraphics: another approach.

This paper discusses the rationale leading to the purchase of a medium resolution computergraphics system and modification of existing computer software for the production of scientific publication graphs and presentation color slides. Capabilities of the system and components are reported.

Computers↗
PubMed1983

The presence of polysaccharide in normal human gastric mucus.

Polysaccharide material was found in the proteolysis glycopolypeptide fraction from normal human gastric mucus. The polysaccharide was identified by carbohydrate and amino acid analyses, by elemental analysis and from its behaviour on density-gradient ultracentrifugation. The polysaccharide is polydisperse with a weight-average molecular mass of 300 000 Da. Over 85% of the polysaccharide consists of galactose, and this represents 26% of all the galactose present in the fractions after beta-elimination with reduction of the glycopolypeptide material.

Amino Acids↗
PubMed1983

Suspected epidural compression of the spinal cord and cauda equina by metastatic carcinoma. Clinical diagnosis and survival.

Data from 133 patients with cancer and suspected compression of the spinal cord or cauda equina was reviewed. Although there were differences in presenting symptoms and signs between the group of 62 patients with compression and the 71 without, no single symptom or sign discriminated adequately between the two groups. Multiple logistic regression was used to try to develop an index of signs and symptoms which could identify those without compression, thereby sparing them a myelogram. Eight characteristics, in combination, proved most effective as an index, but they were not perfect predictors of patients with block. Final diagnoses in the group without compression were: vertebral metastases 35%, carcinomatous meningitis 24%, plexopathy and/or neuropathy 21%, other 30% (10% had two diagnoses). Sixty-six percent of those with compression and 50% of those without compression died within six months, although patients rarely survived for much longer.

Adolescent↗
PubMed1983

Splenic preservation in adults after blunt and penetrating trauma.

This study was carried out to evaluate the possibility and safety of splenic preservation in adults subjected to both blunt and penetrating. In an 18 month period there were a total of 36 splenic injuries studied (in 36 patients): 18 due to blunt trauma, 11 due to gunshot wounds, and 7 due to stab wounds. A total of 18 spleens were repaired: 8 (45 percent) in the blunt trauma group, 4 (36 percent) in the gunshot group, and 6 (85 percent) in the stab wound group. There were no deaths in the entire group nor were there any complications associated with splenic salvage. Splenic preservation after both blunt and penetrating trauma is both safe and feasible in the adult population, except in those instances specified herein.

Adolescent↗
PubMed1983

Fasciola hepatica: inhibition of phosphoenolpyruvate carboxykinase, and end-product formation by quinolinic acid and 3-mercaptopicolinic acid.

Quinolinic acid and 3-mercaptopicolinic acid act as inhibitors of Fasciola hepatica phosphoenolpyruvate carboxykinase. Low concentrations of these compounds (0.1 mM quinolinate and 0.01 mM 3-mercaptopicolinate) resulted in noncompetitive inhibition, which became mixed inhibition at higher concentrations (1.5 and 0.15 mM, respectively). 3-mercaptopicolinic acid proved to be a much more potent effector than quinolinic acid. Both quinolinic acid and 3-mercaptopicolinic acid caused a significant reduction in the total amount of end product excreted, again 3-mercaptopicolinate being more effective than quinolinate. When glucose was present in the medium, both propionate and acetate levels fell significantly with both inhibitors; however, only 3-mercaptopicolinic acid caused an effect in the absence of glucose.

Acetates↗
PubMed1983

Fasciola hepatica: carbohydrate metabolism of the adult.

Glycogen (or exogenous glucose) was the only energy source utilized by adult Fasciola hepatica under a number of different incubation conditions. When exogenous glucose was present in the incubation medium, significant amounts of lactate were excreted. Anaerobically, in the presence of glucose, lactate accounted for 20% of the total end products measured. In the absence of glucose, organic acid production accounted for approximately 60% of glycogen carbon utilized; this value was reduced to 40% in the presence of exogenous glucose. There was no appreciable Pasteur effect.

Acetates↗
PubMed1983

Right hemispheric specialization for mental imagery: a review of the evidence.

An implicit assumption in the literature on functional hemispheric asymmetry is that the right hemisphere plays a special role in mental imagery. Using a definition of mental imagery as quasi-perceptual experience, we draw distinctions among visual imagery, visual recognition memory, and visuospatial abilities. We then review the research literature to evaluate the hypothesis that mental imagery is a specialized function of the right cerebral hemisphere, and find that it receives little unambiguous support. Case reports of loss of imagery are no more frequent with right than with left unilateral brain damage. Systematic studies of brain-injured patients provide some support for the hypothesis, but are also consistent with the alternative hypothesis of bilateral representation of imagery. Commissurotomized patients report dreaming and being able to form visual images. Behavioral and psychophysiological studies of non-brain-injured patients either fail to provide evidence in favor of the hypothesis or can be interpreted as compatible with the alternate hypothesis of bilateral hemispheric involvement in imagery. We conclude that there is, presently, insufficient empirical basis for considering imagery a right hemispheric function. We then discuss implications of this conclusion for future research.

Brain Injuries↗
PubMed1983

Correlation of spontaneous microaggregate formation with the severity of trauma in man.

Blood samples were obtained from 237 consecutive injured patients before any resuscitation. Microaggregate (MA) formation was measured by the screen filtration pressure (SFP) technique. Arterial blood gases were analyzed concomitantly and the respiratory index (RI) calculated. An Injury Severity Score (ISS) was calculated for each patient. The results show a significantly larger amount of trauma in the patients with the higher SFP results (p less than 0.001). Associated with the increase in the amount of MA formation was a significant decrease in arterial pO2 (p less than 0.05) and a significant rise in the RI (p less than 0.005), suggesting a correlation between MA formation and pulmonary impairment. Attempts to prevent or resolve MA formation may result in a decrease in the incidence or severity of post-traumatic pulmonary insufficiency.

Adolescent↗
PubMed1982

Bilateral hemispheric alpha activity during visual imagery.

Subjects responded to questions designed to be answered with or without accompanying visual imagery, while saccadic eye movements and temporoparietal EEG were recorded. Findings of suppressed eye-movement rate and suppressed alpha output during response to the high-imagery questions were interpreted as evidence of the presence of visual imagery. However, the interaction between Question Type and Hemisphere was not significant, indicating equal effect of visual imagery on alpha activity in the two hemispheres, contrary to the popular belief that visual imagery is a function of the right cerebral hemisphere.

Adult↗
PubMed1982

Endocrine activity in air traffic controllers at work. III. Relationship to physical and psychiatric morbidity.

This final report in the series of three examines the relationships between physical health change, psychopathology and work responsiveness to cortisol and growth hormone secretion in air traffic controllers. In contrast to expectations, those who had the lowest rates of mild to moderate physical health change showed a modest tendency to have higher average cortisol. Those men who experienced more psychiatric symptomatology in terms of impulse control problems, alcohol abuse and subjective distress had slightly higher average cortisol values at work. Those men who responded to increased workload with increases in cortisol, possibly reflecting increased job involvement, also had higher average cortisol. Physical health change, levels of psychopathology and cortisol responses to increased workload were statistically independent predictors of average cortisol levels.

Adult↗
PubMed1982

A bullet in the appendix.

An unusual case of a foreign body lodged in the appendix after traumatic intestinal penetration is described. Although rarely found, foreign bodies in the appendix may produce acute appendicitis and other complications which necessitate surgery. An appendectomy is recommended: 1) for all symptomatic patients; 2) in patients with pointed objects retained because such patients are at potential risk for perforation; or 3) in any patient with a foreign body in the appendix who is undergoing intra-abdominal surgery for other reasons.

Adult↗
PubMed1982

Enhanced renin levels after discontinuation of furosemide: additional effects of loop diuretics on renin release.

The rate of recovery of the renin-angiotensin-aldosterone axis after stopping diuretic administration was examined in 18 male patients with essential hypertension. Upright plasma renin activity (PRA) and plasma aldosterone (PA) were measured during sodium restriction (10 mEq sodium intake), after three days of furosemide administration (40 mg BID po) and for five days following cessation of the diuretic. After diuretic administration, the mean PRA level (8.2 +/- 1.7 ng/ml/hr) was significantly elevated compared to the level on low sodium diet (4.2 +/- 0.5 ng/ml/hr). However, the major finding was that PRA levels continued to increase significantly compared to levels during diuresis on days 1 (11.3 +/- 1.7 ng/ml/hr) and 2 (10.8 +/- 1.5 ng/ml/hr) of the postdiuretic period. Mean PA values paralleled PRA responses in the study. Infusion of normal saline on postdiuretic day 1 failed to suppress PRA to levels seen in subjects not receiving diuretics. The postdiuretic period was accompanied by increased urinary sodium reabsorption and decreased urinary potassium excretion and by significant decreases in creatinine, PAH and free water clearance. The mechanism of this sustained renin response several days after cessation of diuretic therapy may be best explained by a prolonged action of furosemide or by partial ongoing volume depletion with reduced sodium load to the distal nephron. Since all patients demonstrated a marked and consistent PRA response after diuretic withdrawal, this time period represents a potent stimulatory challenge for monitering renin responses.

Adult↗
PubMed1982

Hand in hand.

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Adolescent↗