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Biomedical subjects

R A Becker

Publications and source records attributed to R A Becker.

41 records · Page 3Linked to original sources
PubMedDate not supplied

Elevated blood pressure after pinealectomy in the rat.

Previous observations have suggested a role for the pineal gland in regulation of blood pressure. To investigate this possibility, pinealectomy was performed in prepubertal (43-day-old) and postpubertal (55-day-old) male rats. Systolic blood pressure (BP) was measured by the tail cuff method in conscious pinealectomized (Px) and sham pinealectomized (ShPx) rats at various times. In the 3 weeks following surgery, the BP increase after Px was twice that after ShPx (p less than 0.05). During administration of 1% saline as the sole fluid source from day 96-123, hypertension (BP greater than 150 mmHg) was observed in those animals Px at day 43 (p less than 0.05 vs ShPx) but not in those Px on day 55. Moreover, saline consumption was increased in the hypertensive group compared to ShPx controls. There was no significant difference in mean body weight or heart rate between Px or ShPx groups. These data suggest that pinealectomy in the prepubertal period may result in a tendency to hypertension, measurable in conscious rats, which is unmasked by saline administration.

Animals↗
PubMedDate not supplied

Interactions of thyroid hormones and catecholamines in severely burned patients.

A prospective study of thyroid function was performed in 20 thermally injured patients. Serum levels of free thyroxine (FT4) and free 3,5,3'-triiodothyronine (FT3) were measured in 10 patients (mean age, 34 years; mean burn size, 56%) studied during a period of clinical deterioration and in 10 patients of comparable age and burn size who were clinically stable. Both FT4 and FT3 values were significantly lower in the unstable patients, P less than .01. All FT3 values for the unstable patients, 193 +/- 14 pg/dl (mean +/- SE), were beneath the normal range for FT3, 230-669 pg/dl. Interactions of thyroid hormone and catecholamines were assessed in eight additional burned patients (mean age, 31 years, mean burn size, 57%). Plasma norepinephrine correlated negatively with serum T3 (r = -.70; P less than .01). A similar reciprocal relationship was described for plasma epinephrine and serum T3 (r = -.56; P less than .025). The reciprocal relationship described for serum T3 and plasma norepinephrine and epinephrine is consistent with that of similar observations in states of clinical hypothyroidism. In conclusion, the observations of suppression of free thyroid hormone with clinical deterioration and of a reciprocal relationship between T3 and catecholamines suggest that the critically ill burned patient may be chemically hypothyroid; this may be an adaptive response to assumption of metabolic control by the sympathetic nervous system and does not result from caloric deprivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Use of cold iodine in patients with Graves' disease: observations from a clinical practice.

OBJECTIVE: To determine the efficacy and safety of cold iodine after radioactive iodine therapy (RAI) and the effects of prior antithyroid drug therapy in patients with Graves' disease. METHODS: We undertook a review of medical records of 280 consecutive patients with Graves' disease who were treated with RAI followed by cold iodine. Logistic regression methods were used to model treatment failure. RESULTS: Of the 280 patients, 246 (88%) were successfully treated with a single dose of RAI, whereas 34 patients (12%) required further therapy. The mean duration of time to achieve euthyroidism or hypothyroidism in successfully treated patients was 68 days. Of the 209 patients who were never given antithyroid drugs (ATDs), 190 (91%) were successfully treated with a single dose of RAI. No differences were found in patient age, thyroid gland size, or initial free thyroxine index between the successfully treated group and the treatment failure group among those who received RAI alone. Of the 71 patients who had been treated with ATDs before RAI administration, 56 (79%) were successfully treated with a single dose of RAI. The treatment failure rate of 21% in patients who had received ATDs was significantly higher than the 9% failure rate observed in those who were never given ATDs (P = 0.01). Multivariate analysis showed that larger gland size increased the likelihood of treatment failure [c2(2) = 11.76)] and prior treatment with ATDs doubled the risk of treatment failure after adjusting for gland size. No serious adverse events were noted after RAI or cold iodine therapy. CONCLUSION: Treatment of Graves' disease with RAI followed by cold iodine was safe and effective. The use of ATDs before 131I ablation resulted in a 2.3-fold higher treatment failure rate. ATDs need be used only in high-risk persons, and if such therapy is undertaken, higher doses of 131I should be administered to reduce the incidence of treatment failure.

Adolescent↗