PubMed Health⌕ Search

Biomedical subjects

G C Borst

Publications and source records attributed to G C Borst.

10 recordsLinked to original sources
PubMed1989

Inpatient capillary glucose monitoring: a useful adjunct to the management of diabetes in community hospitals.

Nursing personnel in two rural hospitals were taught to measure capillary blood glucose with a reflectance meter. Reflectance meter readings correlated well with laboratory blood glucose on all hospital units (R = .977 to .944) and were clinically useful. Measurements on a designated diabetes unit showed the closest correlation to laboratory measurements (P less than or equal to .001). Capillary blood glucose measurements are a feasible alternative to urine glucose testing in community hospitals.

Blood Glucose Self-Monitoring↗
PubMed1985

The effects of triacetyloleandomycin and oleandomycin phosphate on the glucocorticoid receptor in cultured skin fibroblasts.

Triacetyloleandomycin (TAO) has been described as a "steroid-sparing" drug in that poorly controlled asthmatic patients can be stabilized or improved with the addition of TAO despite decreasing dosages of steroids, specifically methylprednisolone (MP). It is not clear whether the beneficial effects of TAO are due to decreased MP clearance or are due to enhanced glucocorticoid effect peripherally. We tested the latter possibility by studying the interaction of TAO and oleandomycin phosphate (OLEO), the active metabolite of TAO in vivo, with glucocorticoid receptors in dispersed, intact cultured human skin fibroblasts. With the use of cells incubated with [3H]dexamethasone at 22 degrees C, we examined the competitive binding properties of TAO and OLEO (at varying concentrations) with and without MP as compared with several other steroids and MP alone. We also studied the effects on cellular glucocorticoid receptor number and affinity when TAO at a concentration of 4 X 10(-5) alone, at 10(-5) M in combination with a receptor saturating concentration of MP (5 X 10(-8) M), with MP alone, or with OLEO (10(-5) M) combined with MP was added to fibroblasts in the growth phase 1 wk before assay. TAO and OLEO did not compete for the binding of [3H]dexamethasone to the fibroblast glucocorticoid receptor, nor did they alter the binding properties of MP. With prolonged cellular exposure, TAO alone did not alter the number of glucocorticoid receptors (per cell) or their affinity for [3H]dexamethasone. Interestingly, prolonged exposure to saturating concentrations of MP alone decreased glucocorticoid receptor density; this effect was not altered by the presence of TAO or OLEO.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Count↗
PubMed1984

Concurrent renal hypomagnesemia and hypoparathyroidism with normal parathormone responsiveness.

A 24-year-old woman presented with clinical features suggesting hypoparathyroidism: tetany, basal ganglia calcification, and a history of a seizure disorder. Hypocalcemia was present on admission despite therapy with calcium and vitamin D. Hormonal evaluation revealed undetectable parathormone levels and a normal cyclic AMP and phosphaturic response to parathormone infusion, suggesting the diagnosis of idiopathic hypoparathyroidism. Additional testing, however, revealed hypomagnesemia and elevated urinary magnesium levels. Normomagnesemia could not be consistently achieved despite oral magnesium administration. When the serum magnesium level was temporarily normalized via intravenous magnesium supplementation, parathormone levels rose into the normal range. These data indicate that the patient's hypomagnesemia was most likely due to renal magnesium loss. The normalization of her parathormone level during magnesium replenishment, along with the parathormone infusion data, suggests that this patient's hypomagnesemia was responsible for decreased parathormone synthesis and/or secretion, while target tissue responsiveness to parathormone was maintained.

Adult↗
PubMed1983

Fasting decreases thyrotropin responsiveness to thyrotropin-releasing hormone: a potential cause of misinterpretation of thyroid function tests in the critically ill.

We have previously reported that caloric deprivation inhibits peripheral T4 metabolism and blunts the TSH response to TRH in euthyroid obese subjects. To determine whether these phenomena also occur in hypothyroid subjects, T4, T3, rT3, and the TSH response to TRH were measured initially and after a 60-h fast in seven hypothyroid patients. Short term fasting caused a 29% decrement in the maximum serum TSH increment and a 32% decrement in the integrated TSH response to TRH (P less than 0.01). In two subjects with mild hypothyroidism, basal TSH as well as the TSH response to TRH were reduced to levels within the normal range. Specifically, basal TSH values decreased from 7.6 to 3.5 microU/ml and from 11 to 4.1 microU/ml. In the seven subjects, mean serum T3 decreased significantly from 88 to 60 ng/dl, (P less than 0.05) and rT3, initially undetectable in six of seven subjects, rose to detectable or low normal values in four of seven subjects, serum T4 remained at 2.7 micrograms/dl during both study periods. We conclude that 1) fasting induces changes in both peripheral thyroid hormone metabolism and the hypothalamic-pituitary axis in hypothyroid individuals which are qualitatively similar to those that occur in euthyroid subjects; and 2) in certain hypothyroid subjects, fasting alone can decrease basal TSH values to within the normal range. If these data can be extrapolated to critically ill subjects whose caloric intake may be diminished, they suggest that basal TSH concentrations in moderately and severely hypothyroid critically ill subjects will accurately reflect the biochemically hypothyroid state. However, mild degrees of hypothyroidism in critically ill subjects might be overlooked due to the lowering effect of fasting or poor caloric intake alone on basal TSH concentrations.

Adult↗
PubMed1983

Euthyroid hyperthyroxinemia.

An increasing number of disorders that may cause hyperthyroxinemia without thyrotoxicosis have been recognized in recent years. These include acquired and inherited abnormalities of serum thyroid-hormone-binding proteins, peripheral resistance to thyroid hormones, acute nonthyroidal illness, acute psychiatric illness, and some drug-induced conditions associated with nonthyrotoxic elevations of serum thyroxine. In addition to the laboratory finding of elevated serum thyroxine levels, many of these syndromes are also accompanied by abnormalities in triiodothyronine and free thyroid hormone levels, as well as unresponsiveness of thyroid-stimulating hormone to thyrotropin-releasing hormone, all of which further erroneously indicate a diagnosis of thyrotoxicosis. An awareness of these syndromes and alterations in the results of thyroid function tests that accompany them is important to prevent a misdiagnosis of hyperthyroidism and inappropriate therapy.

Amiodarone↗
PubMed1982

Euthyroid familial hyperthyroxinemia due to abnormal thyroid hormone-binding protein.

A family is described in which three members had an elevated total serum thyroxine level and free thyroxine index. Each affected subject was clinically euthyroid and had a normal pulse wave arrival time (QKd), serum triiodothyronine and free thyroxine levels, and a normal serum thyroxine-binding globulin (TBG) concentration. Electrophoresis of their serum with 125I-labeled thyroxine revealed increased thyroxine binding in the albumin region. In addition, this abnormal protein, like thyroxine-binding globulin, bound 125I-labeled triiodothyronine and 125I-labeled reverse triiodothyronine. However, electrophoresis of serum treated by sialidase (neuraminidase) digestion suggested that this abnormal protein is not an anomalous form of thyroxine-binding globulin "buried" in the albumin area. These cases of euthyroid familial hyperthyroxinemia due to an abnormal thyroid hormone-binding protein show that an elevated serum thyroxine level or free thyroxine index is not always sufficient to confirm the presence of thyrotoxicosis.

Child↗