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Biomedical subjects

T A Wilson

Publications and source records attributed to T A Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1967

A theoretical prediction of the normal cardiac oxygen consumption.

A model is described from which the entropy production associated with the process of transporting oxygen and carbon dioxide between the lungs and the muscles of the body can be calculated. The two entropy sources which are assumed to be the dominant ones for this process are the entropy production associated with the metabolism of the heart and the entropy production associated with the diffusion of oxygen and carbon dioxide into and out of the blood. The hypothesis that the observed blood flow is the one for which a given amount of oxygen and carbon dioxide is transported between the lungs and the muscles with minimum total entropy production is used to predict the value of the slope of the cardiac oxygen consumption vs. blood flow curve. At a blood flow of 15 liters/min, the predicted value of the slope of this curve is 1.2 ml/liter.

Biophysical Phenomena↗
PubMedDate not supplied

Alterations in the growth hormone-insulin-like growth factor axis in insulin dependent diabetes mellitus.

The growth hormone (GH)-insulin-like growth factor (IGF) axis and insulin are major anabolic effectors in promoting weight gain and linear growth. These two anabolic systems are interlinked at many levels, thus abnormalities in one of these systems effect the other causing disordered metabolic homeostasis. Insufficient portal insulinization in insulin dependent diabetes mellitus (IDDM) results in hepatic GH resistance and increased production of IGF-binding proteins-1 (IGFBP-1) and IGFBP-2. GH resistance is reflected by decreased hepatic IGF-I production. In addition, changes in other GH-dependent proteins are also observed in IDDM. Increased proteolysis of IGFBP-3 results in reduction of intact IGFBP-3. Serum ALS levels are also slightly diminished in untreated diabetic patients. Hepatic resistance to GH is, at least in part, caused by diminished GH receptors as reflected by diminished circulating GHBP levels. In addition, there is also evidence from experimental and human studies suggesting post-receptor defect(s) in GH action. As a result of these changes, circulating total and free IGF-I levels are decreased during insulinopenia. Lack of negative feed-back effect of IGF-I on GH secretion causes GH hypersecretion which increases hyperglycemia by decreasing sensitivity to insulin. GH hypersecretion in poorly controlled diabetic patients may play a role in the pathogenesis of diabetic vascular complications. Most of these abnormalities in the GH-IGF axis in diabetes are reversed by effective insulinization of the patient. Addition of IGF-I treatment to insulin in adolescents with IDDM allows correction of GH hypersecretion, improves insulin sensitivity and glycemic control, and decreases insulin requirements. The effect of IGF-I treatment on diabetic complications has yet to be seen.

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

Development of a women's wellness center in Almaty, Kazakhstan.

Twelve Women's Wellness Centers were established by American International Health Alliance (AIHA) partnerships in the New Independent States of the former Soviet Union. The services offered by these centers focused on health promotion, disease prevention, and other health and social issues that affect women's health. The innovations in the model include patient-centered care that emphasizes patient choice and the introduction of the role of the nurse educator.

Community-Institutional Relations↗
PubMedDate not supplied

Sample size calculations for rescreening cytologic smears.

OBJECTIVE: To describe a method of calculating sample size if rescreening of cytologic material becomes necessary for legal or other reasons. The number of specimens to be reexamined must be large enough to provide adequate confidence in the results and small enough to minimize the cost of investigation. CONCLUSION: Except under very unusual conditions, the sample size is larger than generally thought.

Cell Biology↗
PubMedDate not supplied

Importance of plasma angiotensin concentrations in a comparative study of responses to angiotensin in the maturing newborn lamb.

Plasma angiotensin concentrations were measured in a longitudinal study of the vascular, renal, and adrenal responses to infusions of angiotensin II (AII) in the maturing newborn lamb. Basal plasma concentrations of angiotensin increased with age and correlated with the rising arterial pressure that occurred with maturation. However, age was a stronger determinant of arterial pressure than was plasma angiotensin concentration. For any given dose of AII per kilogram of body weight, the actual plasma angiotensin concentration achieved increased as the lambs matured and gained weight. Therefore, a comparative study of biologic responses to AII in maturing animals must be based on actual plasma angiotensin concentrations achieved rather than on dose of AII infused per kilogram of body weight. When analyzed on the basis of actual plasma angiotensin concentration, the increase in arterial pressure and the suppression of plasma renin activity in response to increasing plasma angiotensin concentrations did not differ significantly as the lambs matured. However, the increment in plasma aldosterone concentrations in response to increasing plasma angiotensin concentrations was diminished in immature lambs (less than 18 days) when compared to the aldosterone responses in the same lambs at older ages.

Aging↗
PubMedDate not supplied

Hypothalamic dysfunction at ideal body weight simulating anorexia nervosa.

Hypothalamic dysfunction is common in patients with anorexia nervosa, but typically follows reductions of body weight to well below ideal body weight. We report a patient with hypothalamic dysfunction accompanying volitional weight reduction, whose body weight never fell below ideal body weight and whose hypothalamic function improved following weight gain. These observations suggest that the "set point" for normal hypothalamic function may exceed ideal body weight in some patients. In addition, hypothalamic dysfunction may persist for months following weight gain and the resumption of menses.

Adolescent↗
PubMedDate not supplied

Growth hormone treatment in growth retarded children with end stage renal failure: effect on free/dissociable IGF-I levels.

Growth retardation in children with endstage renal disease (ESRD) is associated with normal to slightly low concentrations of insulin-like growth factor (IGF)-I and increased concentrations of IGF-binding proteins (IGFBPs) in serum. Consequently, IGF-I bioactivity is reduced in serum from uremic patients presumably due to a decrease in the concentration of free IGF-I. Improvement of linear growth with growth hormone (GH) treatment of uremic children is thought to be due to increased IGF-I/IGFBP ratio, thus resulting in increased free IGF-I levels during treatment. The purpose of the present study was to determine whether free/dissociable IGF-I levels are in fact low in uremic children and whether increased growth velocity during GH treatment is associated with an increase in the free IGF-I concentration. Serum total and free/dissociable IGF-I concentrations were measured in 5 children with ESRD before and during treatment with GH, and in control children matched for age, pubertal status, and body mass index. Height velocity increased from 3.7 +/- 1.0 cm/yr to 6.5 +/- 1.2 cm/yr with an increment in height SDS at the end of the first year of GH treatment. Free/dissociable IGF-I concentrations tended to be lower in uremic children compared to control children (3.0 +/- 0.3 vs 7.3 +/- 2.1 micrograms/l, respectively). During GH treatment, free/dissociable IGF-I levels increased significantly to 8.5 +/- 1.0 micrograms/l at 3 months and 6.9 +/- 1.4 micrograms/l at 6-24 months, p < 0.05 compared to pretreatment. Total IGF-I levels were 243 +/- 18 micrograms/l in children with ESRD before treatment and these values also increased during GH treatment (740 +/- 114 micrograms/l at 3 months and 442 +/- 44 micrograms/l at 6-24 months, p < 0.05, compared to pretreatment). Total IGF-I concentration in the control group was 439 +/- 114 micrograms/l. These results support the hypothesis that growth retardation in children with chronic renal failure is associated with a reduction in the concentration of free, biologically available IGF-I, and that increased growth velocity during GH treatment of these children is associated with restoration of free IGF-I concentrations.

Body Height↗
PubMedDate not supplied

Normal growth in a patient with septo-optic dysplasia despite both growth hormone and IGF-I deficiency.

A 17 year-old female with septo-optic dysplasia (SOD) and hypopituitarism who has grown normally despite GH deficiency is presented. Her serum was examined to test current hypotheses to explain the phenomenon of growth without GH. The patient's serum possessed potent in vitro growth-promoting activity (GPA) in an erythroid progenitor-cell clonal proliferation assay consistent with the patient's normal growth performance. In contrast to previously reported cases of growth without GH, total IGF-I concentrations were very low in this patient, precluding IGF-I being responsible for the observed GPA and normal growth pattern. Furthermore, circulating free IGF-I was also low which is reported for the first time in such a case. A detailed picture of IGF-binding proteins is also presented. To test the hypothesis that hyperinsulinemia might be responsible for the observed GPA, in vitro GPA experiments were performed before and after removal of insulin by immunodepletion. Neither partial nor complete removal of insulin abolished the in vitro cell proliferation response. These data demonstrate that neither IGF-I nor insulin is the factor responsible for GPA in at least this patient with SOD and growth without GH.

Abnormalities, Multiple↗
PubMedDate not supplied

Effect of hyperthyroidism on insulin-like growth factor-I (IGF-I) and IGF-binding proteins in adolescent children.

A study was performed on adolescent hyperthyroid patients to determine the effects of hyperthyroidism on insulin-like growth factor (IGF)-I and its binding proteins. Serum concentrations of immunoreactive total and free IGF-I, and IGF binding protein (IGFBP)-2 and IGFBP-3 were determined before and after correction of hyperthyroidism in eight patients with Grave's disease and compared to control patients matched for age, sex and pubertal stage. The concentration of serum total IGF-I was not significantly different in the hyperthyroid state and euthyroid state, and did not differ significantly from euthyroid controls. IGFBP-2 levels were elevated three-fold in hyperthyroid patients at the time of diagnosis of hyperthyroidism compared to control subjects, and fell significantly during treatment. There was also a significant positive correlation between serum IGFBP-2 concentrations and thyroxine (T4) concentrations in all subjects. Serum IGFBP-3 concentrations were also elevated in hyperthyroid subjects and normalized with correction of the hyperthyroidism. There was also a positive correlation between serum T4 and IGFBP-3 concentrations in all subjects. Despite the hyperthyroid-induced elevations in IGFBP-2 and -3, no significant difference in the serum concentration of free IGF-I before or after correction of the hyperthyroid condition was observed. We conclude that hyperthyroidism does not cause alterations in the serum concentrations of either free or total IGF-I. However, both serum IGFBP-2 and IGFBP-3 concentrations were elevated during hyperthyroidism and correlated with serum T4 levels. These abnormalities reversed with normalization of thyroid function.

Adolescent↗