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Biomedical subjects

M M Peterson

Publications and source records attributed to M M Peterson.

9 recordsLinked to original sources
PubMed2005

Assisted reproductive technologies and equity of access issues.

In Australia and other countries, certain groups of women have traditionally been denied access to assisted reproductive technologies (ARTs). These typically are single heterosexual women, lesbians, poor women, and those whose ability to rear children is questioned, particularly women with certain disabilities or who are older. The arguments used to justify selection of women for ARTs are most often based on issues such as scarcity of resources, and absence of infertility (in lesbians and single women), or on social concerns: that it "goes against nature"; particular women might not make good mothers; unconventional families are not socially acceptable; or that children of older mothers might be orphaned at an early age. The social, medical, legal, and ethical reasoning that has traditionally promoted this lack of equity in access to ARTs, and whether the criteria used for client deselection are ethically appropriate in any particular case, are explored by this review. In addition, the issues of distribution and just "gatekeeping" practices associated with these sensitive medical services are examined.

Attitude of Health Personnel↗
PubMed1998

Germination and seedling development of switchgrass and smooth bromegrass exposed to 2,4,6-trinitrotoluene.

It is estimated that explosives contaminate approximately 0.82 million cubic metres of soil at former military installations throughout the US; major contaminants often include 2,4,6-trinitrotoluene (TNT) and its degradation products. At some sites, phytoremediation may be a viable option to incineration or other costly remediation treatments. Grasses may be particularly suited for remediation because of their growth habit and adaptability to a wide range of soil and climate conditions. We characterized the effects of TNT on germination and early seedling development of switchgrass and smooth bromegrass to evaluate their potential use on contaminated sites. Switchgrass and smooth bromegrass seeds were germinated in nutrient-free agar containing 0 to 60 mg TNT litre(-1). Smooth bromegrass germination decreased as TNT concentration increased, while switchgrass germination was unaffected by TNT. Concentrations up to 15 mg TNT litre(-1) did not affect switchgrass root growth rate, but bromegrass root growth was reduced at TNT concentrations above 7.5 mg litre(-1). At 7.5 mg TNT litre(-1), however, shoot growth rate was reduced in both species. Examination at 20-fold magnification revealed switchgrass radicles were unaffected by TNT, while smooth bromegrass radicles appeared slightly swollen. Results indicate switchgrass is more tolerant of TNT than smooth bromegrass, but the establishment of both species may be limited to soil containing less than 50 mg kg(-1) of extractable TNT.

Journal Article↗
PubMed1996

TNT and 4-amino-2,6-dinitrotoluene influence on germination and early seedling development of tall fescue.

Cost-effective and environmentally acceptable methods are needed to remediate munitions-contaminated soil. Some perennial grass species are tolerant of soil contaminants and may promote remediation because of their high water use and extensive fibrous root systems. The effects of 2,4,6-trinitrotoluene (TNT) and its reduction product, 4-amino-2,6-dinitrotoluene (4ADNT), on germination and early seedling development of tall fescue (Festuca arundinacea Schreb.) were determined. Tall fescue seeds were germinated in nutrient-free agar containing 0-60 mg TNT litre(-1) or 0-15 mg 4ADNT litre(-1). Germination decreased linearly as TNT concentration increased but was not significantly affected by 4ADNT at these concentrations. Concentrations less than 30 mg TNT litre(-1) or 7.5 mg 4ADNT litre(-1) had little effect on seedling growth and development. Higher TNT or 4ADNT concentrations substantially delayed seedling development, caused abnormal radicle tissue development, and reduced secondary root and shoot growth. Seedling respiration rates decreased linearly with increasing TNT concentration. Experiments indicate that tall fescue may be grown in soils that maintain soil solution concentrations of 30 mg TNT litre(-1) or less.

Journal Article↗
PubMed1995

Pioglitazone attenuates diet-induced hypertension in rats.

Consumption of diets rich in fats or sugars is correlated with the onset of insulin resistance and hypertension in rats. In the present study, rats were fed diets that induce hypertension; 50% of the rats were also treated with pioglitazone, a thiazolidinedione derivative that sensitizes target tissues to insulin and decreases plasma insulin concentration in insulin-resistant animals. Pioglitazone treatment prevented the development of hypertension and reduced plasma insulin concentration by 70% and 37% in rats fed a high-fat or glucose diet, respectively (P < .05 compared with rats fed the same diet without pioglitazone). In rats fed a control diet, neither insulin nor blood pressure (BP) was affected by pioglitazone treatment. The effect of pioglitazone on insulin and BP could not be attributed to a reduction in body weight, since pioglitazone increased the weight gain of rats fed the high-fat or glucose diet. These findings suggest that in rats fed a diet high in fat or glucose, treatment with pioglitazone maintains plasma insulin concentration and BP at control levels, regardless of body weight.

Animals↗
PubMed1994

Hypertensive effect of polyunsaturated dietary fat.

Male Sprague-Dawley rats were fed a diet high in either saturated fat (lard) or polyunsaturated fat (corn oil) beginning at 10 weeks of age. After 10 weeks of diet treatment, blood pressure (BP) was 17% higher in rats fed saturated fat and 8% higher in rats fed polyunsaturated fat than in rats fed a low-fat control diet. Rats fed the lard diet became obese, and their fasting insulin levels were elevated (38% above control). These data demonstrate that both saturated and polyunsaturated dietary fats induce hypertension.

Animals↗
PubMed1993

Adrenal medulla as a mediator of diet-induced hypertension.

Male Sprague-Dawley rats fed either a high-fat or glucose-enriched diet for 10 wk developed higher blood pressure (BP) and higher urinary catecholamine excretion than rats fed a control diet. After 10 wk of diet treatment, systolic BP was 164 +/- 3, 156 +/- 2, and 145 +/- 4 mmHg in rats fed the high-fat, glucose, and control diets, respectively (P < 0.02 vs. control). During weeks 7-9 of diet treatment, excretion of epinephrine and norepinephrine was increased in hypertensive rats (those fed the high-fat or glucose diet) when compared with rats fed the control diet (P < 0.001). The purpose of this study was to determine whether the hypertensive response to nutrients could be prevented by prior surgical removal of the adrenal medulla. Adrenal demedullation nearly abolished epinephrine excretion, attenuated norepinephrine excretion, and completely blocked the hypertensive response to dietary fat and glucose. These findings suggest that adrenal medullary catecholamines play a role in the hypertensive response to nutrients.

Adrenal Medulla↗
PubMed1991

Hypertension and sympathetic hyperactivity induced in rats by high-fat or glucose diets.

Male Sprague-Dawley rats fed either a high-fat diet or a glucose-enriched diet developed higher blood pressure (BP) than rats fed a control diet. After 8 wk of diet treatment systolic BP was 11% higher (P less than 0.01) in fat-fed rats and 7% higher (P less than 0.05) in glucose-fed rats when compared with rats fed the control diet. Rats fed the high-fat diet developed hypertension only when they were allowed to overeat and become obese and hyperinsulinemic. But when their feeding was restricted to prevent obesity and hyperinsulinemia, they remained normotensive. In contrast, elevated BP developed in rats consuming the glucose diet in the absence of obesity or hyperinsulinemia. After 7 wk of diet treatment, urinary norepinephrine excretion was 1.9 +/- 0.1, 1.9 +/- 0.1, and 1.5 +/- 0.1 micrograms/day in rats fed the high-fat, glucose, and control diets, respectively (P less than 0.05 vs. control). Higher norepinephrine excretion in hypertensive rats suggests that increased sympathetic nervous system (SNS) activity might participate in mediating the effects of dietary fat or glucose on BP. In addition, insulin may contribute to raising BP in rats fed the high-fat diet, either directly or indirectly through its stimulatory effect on the SNS. We conclude that chronic feeding of diets high in fat or glucose increases BP and enhances SNS activity in rats.

Animals↗
PubMed1982

Effect of radioiodine on stimulatory activity of Graves' immunoglobulins.

The effects of 131I therapy on the activity of thyroid stimulating antibody (TSAb) and thyrotrophin binding inhibiting immunoglobulin (TBII) in nineteen patients with Graves' disease have been studied. Prior to 131I administration TSAb was detected in 84%, and TBII in 68% of patients. Following 131I administration TSAb and TBII were detectable in 100% of patients. The elevation 3 months after treatment of the means of both the TSAb and TBII indices for the group of nineteen patients was highly significant compared with pre treatment values. All the patients went into remission during the course of the study and the TSAb index declined in all patients, becoming undetectable in eleven; TBII also declined in most patients but remained detectable in thirteen. The study furthermore afforded the opportunity for a direct comparison of binding with stimulatory activity. These results show that after 131I therapy for Graves' hyperthyroidism there is a transient increase in TSAb as well as TBII, followed by a decline, and that the measurement of binding and stimulatory activities are in good general agreement.

Antibodies↗