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Biomedical subjects

M Gee

Publications and source records attributed to M Gee.

At least 37 records · Page 2Linked to original sources
PubMed1990

Diagnosis of delayed cerebral radiation necrosis following proton beam therapy.

A 27-year-old man developed delayed cerebral radiation necrosis following proton beam therapy to an arteriovenous malformation. Neuroimaging with technetium 99m diethylenetriamine penta-acetic acid and positron emission tomographic scanning with fludeoxyglucose F 18 aided in his evaluation. Significant improvement of his neurologic deficits resulted from corticosteroid therapy. Clinical resolution was corroborated by serial computed tomographic scans demonstrating regression of the abnormality (a mass lesion). Various facets of radiation injury are discussed, including pathogenesis, risk factors, diagnosis, and therapy.

Adult↗
PubMed1990

Drug use prevention programs, gender, and ethnicity: evaluation of three seventh-grade Project SMART cohorts.

One-year follow-up data from three seventh-grade cohorts of Project SMART were examined to assess the effects of two social psychology-based programs within each of six subgroups: males, females, Asians, blacks, Hispanics, and whites. The three cohorts (total N = 5,070) were those receiving curriculum or serving as controls as seventh-graders in 1982-1983, 1983-1984, and 1984-1985 school years. The outcome measures used were composite indices based on lifetime and recent use items for cigarettes, alcohol, and marijuana. The major analysis was ANCOVA on classroom means for the composite indices at post-test, using pretest classroom means for the indices as a covariate. The results showed clear prevention effects for females but not for males. Overall prevention effects were strongest for cigarette smoking, but were also evident for alcohol. Significant sex by program interactions, showing differential program effects for males and females, were found for cigarettes and marijuana, but not for alcohol. There was a nonsignificant trend suggesting that the programs were most effective for Asians and least effective for whites.

Adolescent↗
PubMed1989

Long-term follow-up of weight status of subjects in a behavioral weight control program.

Few studies have examined the long-term effectiveness of behavioral weight control programs. Interpretation of the results from these studies has been limited due to small sample size, use of only one sex, and the number of evaluation parameters. A 2-year follow-up study was designed to assess the effectiveness of a behavioral weight control program on 123 obese male and 386 obese female subjects. Body weights were measured by dietitians at baseline and after an 8-week treatment program. Two-year follow-up weights were self-reported from a mailed questionnaire. The subjects' mean weight at baseline was 185.6 +/- 43.4 lb (no. = 509). Their mean percent over ideal body weight at baseline was 29.7%. Following an 8-week treatment period, mean weight was 176.4 +/- 41.3 lb (no. = 509), yielding a mean weight loss of 9.2 +/- 6.4 lb. Weight change after the 8-week treatment period ranged from a loss of 37 lb to a gain of 5 lb. The 2-year follow-up study showed that mean weight of the 498 subjects was 179.8 +/- 42.9 lb, yielding a mean weight loss of 5.8 +/- 15.5 lb. Weight change ranged from a loss of 71 lb to a gain of 47 lb. After 2 years, 325 subjects (65.3%) were still below their baseline weights, 182 subjects (36.6% of the entire study group) had maintained or enhanced the weight loss achieved during treatment, and 80 subjects (16.1%) weighed at least 10% less than their baseline weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Riboflavin deficiency and glutathione metabolism in rats: possible mechanisms underlying altered responses to hemolytic stimuli.

Riboflavin deficiency suppresses parasitic growth in malaria. Three possible mechanisms have been proposed previously to explain the survival advantage of riboflavin-deficient hosts: a) enhanced fragility of red blood cells (RBC), b) decreased formation of reticulocytes and/or c) decreased concentrations of reduced glutathione (GSH) and ATP. The validity of these proposed mechanisms was tested by investigating whether riboflavin deficiency alters the hemolytic response to three stimuli: hydrogen peroxide (H2O2), a hypotonic medium or ferriprotoporphyrin IX (FP). Reticulocyte counts and concentrations of ATP and GSH were also determined. The percentage of hemolysis induced by H2O2 or FP was significantly less in riboflavin-deficient than in control animals. By contrast, hemolytic response to a hypotonic medium was enhanced during riboflavin deficiency. Despite diminished activity of glutathione reductase and normal glutathione peroxidase activity during riboflavin deficiency, the erythrocyte concentration of GSH was increased over that in control animals. Concentrations of ATP and hemoglobin in erythrocytes as well as the reticulocyte count were unaltered during riboflavin deficiency. Thus, diminished malarial parasitemia in riboflavin-deficient animals occurs despite greater resistance of RBC to either H2O2- or FP-induced hemolysis, and in the presence of a normal reticulocyte count and erythrocytes ATP concentration. Results of this study raise the possibility that Plasmodium parasites have greater requirements for flavin coenzymes, GSH or ATP than those of host erythrocytes, which may explain the apparent protection of the riboflavin-deficient host from malaria.

Adenosine Triphosphate↗
PubMed1987

Age-related olfactory and taste changes and interrelationships between taste and nutrition.

This article critically reviews the literature on age-related olfactory and taste changes and the interrelationships between nutrition and taste. Age-related taste alterations are controversial, but there is consensus on an olfactory decline with age. Much of the age-related chemoreceptive research has used inappropriate methodology, thus leaving many findings inconclusive. Changes in the taste system with age may be related to nutrient intake, which in turn can be influenced by taste. Literature on such interrelationships is limited. Vitamins A, thiamin, B-6, B-12, folacin, zinc, and copper are thought to influence taste function. Moreover, those nutrients are of concern in the aged. The use of appropriate methodology is critical not only for the sensory but also for the nutritional aspects, particularly for qualitative and quantitative assessments of nutrient intakes. This review considers the experimental deficiencies (small sample size, inappropriate age range, inadequate psychophysical and stimuli presentation procedures, and poor dietary intake assessment) of studies reported in the literature and suggests major needs for research.

Aging↗
PubMed1984

Protein-energy intake and malnutrition in Crohn's disease.

A detailed nutrient assessment was made of 23 male and 24 female patients with Crohn's disease who entered sequentially into an outpatient clinic. Assessment included 48-hour dietary recall, anthropometric measurements, and biochemical and hematological tests appropriate to characterize protein-energy malnutrition. Approximately 40% of patients had energy intakes equal to only two-thirds of the Recommended Dietary Allowance (RDA). Three men and five women had relative body weights less than 85% of standard, but body weight was not correlated with energy intake. Relative body weight was correlated with arm muscle circumference in both male and female patients and with triceps skinfold and total lymphocyte count in women. Although the mean protein intake was greater than 150% of the RDA, evidence of protein malnutrition included low arm muscle circumference in 14% of the men and 15% of the women, low serum albumin concentration in 13% of the women, and low total lymphocyte count in one-half of the patients. The Crohn's disease activity index was correlated significantly with serum albumin, energy intake, and duration of disease in men and with serum ferritin and hemoglobin concentration in women. Thus, a reduced relative body weight or reduced serum albumin was not uncommon in patients with Crohn's disease but did not necessarily occur in those with reduced intakes of protein and energy. However, a low relative body weight may indicate need for further nutritional assessment.

Adolescent↗
PubMed1984

Vitamin and iron intake in patients with Crohn's disease.

A descriptive study was conducted in 23 male and 24 female adult patients with Crohn's disease to assess nutritional status. The mean daily intake of vitamin B6 and folate by the men and the women and of iron by the women was less than the Recommended Dietary Allowances. However, the range of individual intakes varied widely. According to Nutrition Canada Interpretive Standards, 50% of the female patients had inadequate intakes of iron; 13%, of riboflavin; 21%, of thiamin; and 21%, of vitamin A. The men consumed significantly less vitamin A and folate per 1,000 kcal than the women. Serum folate was the only laboratory parameter that correlated with nutrient intake; it was correlated with dietary folate, vitamin C, vitamin B12, and vitamin B6 intakes in the women only. Serum folate was low in 21% of the men and 26% of the women. Thus, a low serum folate was predictive of a potential risk of nutritional deficiency of folate and of vitamins B6, B12, and C. This study demonstrated that nutrient intake was reduced in some patients and therefore could be a factor contributing to observed nutritional deficiency in Crohn's disease.

Adolescent↗
PubMed1983

Effects of dietary manipulation on vascular status of patients with peripheral vascular disease.

In a one-year, double-blind clinical trial, 45 patients with peripheral vascular disease (PVD) were randomly assigned to either the American Heart Association Hyperlipidemia Diet C (n = 20) or a low-fat, high-fiber, complex carbohydrate diet similar to the Pritikin Maintenance Diet (n = 25). Vascular status and blood lipid levels were monitored at 0, 2, 4, 6, and 12 months. Walking distance increased significantly in both groups, with no difference between groups. No vascular parameters changed significantly, suggesting that increased walking distance was due to improved metabolic capacity of the muscle. A trend toward lower blood lipid values was observed, with no significant differences within or between groups. We conclude that while patients with PVD benefit from a program of diet and exercise, there is no apparent advantage to the more difficult complex carbohydrate diet.

Aged↗
PubMed1983

Multiple transduction mechanisms are likely involved in calcium-mediated exocrine secretory events in rat parotid cells.

The parotid gland of the aged rat provides an example of an altered alpha 1-adrenergic physiologic response (K+ efflux) resulting from a postreceptor perturbation in signal transduction mechanisms (Ito, H., Baum, B. J., Uchida, T., Hoopes, M. T., Bodner, L. & Roth, G. S. (1982) J. Biol. Chem. 257, 9532-9538). This alteration in gland function can be completely circumvented by eliciting K+ efflux via the Ca2+-ionophore, A23187, at several Ca2+ concentrations (ibid.). Since Ca2+ is purported to mediate other secretory events in the rat parotid, we have probed neurotransmitter regulated Ca2+ mobilization and secretory mechanisms in this tissue by employing an aging paradigm. The responses studied were alpha-adrenergic- and muscarinic-cholinergic-mediated K+ efflux, 45Ca2+ release, and amylase secretion. No differences were detected between young (3 months) and old (24 months) cell preparations for any muscarinic-cholinergic agonist-induced response studied. Following alpha-adrenergic stimulation, K+ efflux and 45Ca2+ release from old cell preparations were reduced markedly, while no changes were found for the amylase secretion response. These results suggest that 1) alpha-adrenergic and cholinergic signal transduction mechanisms for K+ efflux and 45Ca2+ release are dissociated in cells of the rat parotid gland, and 2) following alpha 1-adrenergic stimulation, signal transduction likely proceeds by at least two pathways, one which is apparently involved in protein excytosis (intact in cells from old rats) and the other which is apparently involved in K+ efflux and 45Ca2+ release (perturbed in old cells).

Aging↗
PubMed1981

The effect of prostacyclin infusion on endotoxin-induced lung injury.

Lung injury produced by endotoxin is characterized by both pulmonary hypertension and increased pulmonary vascular permeability. Prostacyclin (PGI2) has been found to be a vasodilator and a membrane stabilizer. The purpose of this study was to determine the effectiveness of PGI2 in preventing endotoxin injury. Eight sheep with chronic lung lymph fistula were given both Escherichia coli endotoxin (2 microgram/kg) alone and endotoxin plus an immediate infusion of PGI2 (0.1 to 0.2 microgram/kg/min) for a 5-hour period; the studies were performed 4 days apart. The endotoxin injury was characterized by early severe pulmonary hypertension, with pulmonary artery pressure increasing from 18 +/- 0.6 to 40 +/- 3.1 mm Hg and lung lymph flow (QL) increasing threefold. This was followed in about 3 hours by an increase in permeability characterized by an increasing lymph to plasma protein ratio (0.63 to 0.74) and a threefold increase in QL. In seven of eight animals infused with PGI2 the pulmonary hypertension and alteration in QL in the early and later phases were significantly decreased. In four paired studies, prostaglandins PGE, PGF2 alpha, and PGI2 as 6-keto PGF1 alpha were measured in lymph and plasma. PGF2 alpha and PGI2 were significantly increased in lung lymph during the early hypertensive phase immediately after endotoxin injection, but returned to baseline during the later phase. In the PGI2 infusion studies, PGF2 alpha showed the same pattern of response, but PGI2 was increased to much higher levels in lymph and plasma, as compared to values of endotoxin alone. The higher plasma values corresponded with less severe lung injury. The one animal not protected by PGI2 had the lowest plasma PGI2 level. We therefore found PGI2 to protect the lung against injury from endotoxin.

Animals↗
PubMed1981

Leukocytes, platelets, and thromboxane A2 in endotoxin-induced lung injury.

The relationship of leukocytes, platelets, and thromboxane A2 (TxA2) to endotoxin-induced lung injury was studied by use of chronic pulmonary lymph fistula in 12 adult female sheep. Endotoxin-induced lung injury in sheep was characterized by an early pulmonary hypertensive phase followed by a phase of increased capillary permeability. A profound leukopenia occurred early after endotoxin infusion and persisted during both phases of the injury. TxA2 levels (measured as its metabolite thromboxane B2) were significantly increased during the hypertensive phase and then returned rapidly to baseline. Levels were higher in lymph than in plasma, implying local generation in lung. Platelet count decreased transiently later in the permeability phase, rapidly returning toward baseline in animals that survived. The decrease in platelets occurred after TxA2 levels had returned to baseline, suggesting that TxA2 may be coming from sources other than platelets. We conclude that leukocytes appear to play a major role in initiating endotoxin-induced lung injury, and TxA2 may be contributing to pulmonary hypertension. Platelets, on the other hand, seem to be transiently sticking to an already damaged endothelium, with the degree of sequestration indicative of the severity of the injury.

Animals↗
PubMed1976

Mechanism of alveolar flooding in acute pulmonary oedema.

In severe pulmonary oedema, the alveoli fill rapidly with fluid of essentially the same protein composition as free interstitial fluid. The usual explanation is that the normally 'tight' alveolar epithelial intercellular junctions suddenly become freely permeable to proteins. But the pathophysiological basis for such a change is unknown. In seven anaesthetized dogs one lower lobe was filled with iso-osmotic fluid containing 125I-labelled albumin. The calculated alveolus-blood albumin permeability over three hours averaged 0.06 X 10(-7) cm/s. It decreased nearly 50% when the alveolar tracer concentration was tripled for three more hours. At autopsy, large interstitial free fluid cuffs around blood vessels and airways were found. Isolated lung lobes were filled with isosmotic fluid containing tracer albumin at 10 and 20 cmH2O (0.98-1.96 kPa) airway pressure. Free interstitial fluid cuffs developed within 30 and 10 minutes, respectively. The tracer protein concentration in the cuff fluid averaged 0.9 that of the alveolar fluid. It is postulated that the terminal airway epithelium is normally permeable to protein and water. In acute pulmonary oedema alveolar flooding may occur along the same pathway after the loose interstitial tissue space is fluid-filled and its pressure exceeds that in the airway. The anatomical site of the bulk fluid and protein leak has not been identified.

Acute Disease↗
PubMed1976

Microsomal reductive glycosidase.

Rat liver microsomes contain a phenobarbital inducible, NADPH dependent, reductive glycosidase capable of cleaving several anthracycline antibiotics, including adriamycin and daunorubicin, to deoxyaglycone products. The pH optimum for the reaction ranges from 7 to 7.4, and no metal requirements are noted. Molecular oxygen reversibly inhibits the microsomal enzyme greater than 95% at 20% oxygen partial pressure. Carbon monoxide, SKF 525A and sulfhydryl reagents are not inhibitory to the reaction, but the enzyme is sensitive to Cu++ and Zn++. Since the intact glycoside is necessary for conversion to the deoxyaglycone and a possible intermediate hydroxylated aglycone is not reduced to the deoxyaglycone, a concerted reaction mechanism is proposed. The reductive glycosidase activity is also present in rat brain, kidney and other tissues. Sensitivity of this enzyme to molecular oxygen suggests a possible regulatory role for the enzyme in vivo.

Animals↗