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Biomedical subjects

R F Spark

Publications and source records attributed to R F Spark.

At least 19 recordsLinked to original sources
PubMed2002

Yohimbine treatment of organic erectile dysfunction in a dose-escalation trial.

Yohimbine has had questionable effects in men with organic erectile dysfunction. We conducted this study to better define the population of men responsive to yohimbine, because tobacco was thought to affect a regimen of yohimbine more than other risk factors. We measured nocturnal penile tumescence with the RigiScan monitor, hormone profiles, answers to the Florida Sexual Health Questionnaire, and clinical responses at baseline and after two different doses of yohimbine in 18 nonsmoking men with erectile dysfunction. Of the 18 men, nine (50%) were successful in completing intercourse in more than 75% of attempts. The yohimbine responders were men with less severe erectile dysfunction as manifested by improved increased rigidity on RigiScan testing, higher Florida Sexual Health Questionnaire scores, and slightly higher levels of serum testosterone. Yohimbine is an effective therapy to treat organic erectile dysfunction in some men with erectile dysfunction.

Adrenergic alpha-Antagonists↗
PubMed1990

Investigation of reports of sexual dysfunction among male chemical workers manufacturing stilbene derivatives.

A Health Hazard Evaluation was conducted by the National Institute for Occupational Safety and Health in an area of a large chemical plant that manufactured the stilbene derivative 4,4'-diaminostilbene-2,2'-disulfonic acid, an intermediate used for the production of optical brightening agents. Men employed in the area reported problems with impotence. The study population consisted of 44 men aged 20-57 years (mean age 37) employed in the area at the time of the evaluation. An industrial hygiene investigation, health and work history questionnaire survey, physical examinations, and blood chemistry and serum hormone evaluation were conducted. Fourteen percent of the men reported symptoms of impotence over the preceding 6 or more months, 7% had potency problems of shorter duration, and 7% were not currently impotent but had experienced impotence for 6 or more months in the past; 36% experienced decreased libido, all since beginning work in the production area. Low levels of serum testosterone (less than 350 ng/dl) were observed in 37% of the men. The low serum testosterone concentrations were not accounted for fully by diurnal variation or an effect of rotating shift work. It is suggested that exposures to chemicals possessing estrogenic activity may be related to the observed health effects in these workers.

Adult↗
PubMed1984

Prevention of acute mountain sickness by dexamethasone.

Acute mountain sickness is a syndrome that occurs when unacclimatized persons ascend rapidly to high altitudes. It is postulated that cerebral edema causes its symptoms. Since dexamethasone is useful in treating some forms of cerebral edema, we investigated its role in the prevention of acute mountain sickness. Using a double-blind crossover design, we exposed eight young men to a simulated altitude of 4570 m (15,000 ft) on two occasions. By random assignment, each subject received dexamethasone (4 mg every 6 hours) or placebo for 48 hours before and throughout the 42-hour exposure. The presence of symptoms of acute mountain sickness was established by two methods: a questionnaire and an interview by a physician. Dexamethasone significantly reduced the symptoms of acute mountain sickness. During dexamethasone treatment, the cerebral-symptom score (mean +/- S.E.) decreased from 1.09 +/- 0.18 to 0.26 +/- 0.08, and the respiratory-symptom score decreased from 0.64 +/- 0.09 to 0.31 +/- 0.06 (both, P less than 0.05). As judged by the interviewing physician, the symptom score decreased from 1.10 +/- 0.11 to 0.28 +/- 0.07 (P = 0.01). We conclude that dexamethasone may be effective in preventing the symptoms of acute mountain sickness.

Acute Disease↗
PubMed1984

Hypogonadism, hyperprolactinaemia, and temporal lobe epilepsy in hyposexual men.

Previously unrecognised temporal lobe epilepsy (TLE) was diagnosed in 11 of 16 hyposexual men. 6 had neuroendocrine abnormalities (hypogonadism in 4 and hyperprolactinaemia in 2). 4 men with hypogonadism and TLE had persistently subnormal serum testosterone, with a blunted luteinising hormone (LH) response to luteinising hormone releasing hormone (LHRH) in 2 and, in these men, unlike those with isolated hypogonadism, there was no improvement in libido or potency when parenteral testosterone was given. Men with TLE and hyperprolactinaemia had normal serum testosterone and an enhanced serum LH response after LHRH, but effective doses of the dopaminergic agonists, bromocriptine or pergolide, did not produce sustained normoprolactinaemia. In the men with neuroendocrine dysfunction and TLE the most effective therapeutic sequence was first to treat the epilepsy with anticonvulsants and then to add appropriate neuroendocrine therapy. In 2 men hormone levels became normal and sexual function was restored on anticonvulsant therapy alone.

Adult↗
PubMed1984

Plasma renin substrate, renin activity, and aldosterone levels in a sample of oral contraceptive users from a community survey.

Fasting plasma renin substrate (PRS), plasma renin activity (PRA), plasma aldosterone (PA), and blood pressure (BP) levels were measured from 212 apparently healthy normotensive nonpregnant white women aged 21 to 39 years, selected on the basis of oral contraceptive (OC) use of nonuse in 1976 following a community survey in East Boston. The mean PRS level was 7118 ng/dl among OC users and 1935 ng/dl among nonusers (p less than 0.0001). In contrast, mean PRA was 2.9 ng of angiotensin 1 per milliliter per hour among users and 3.0 ng of angiotensin l/ml/hr among nonusers (p = NS); mean PA levels were 26.2 ng/dl and 25.4 ng/dl, respectively (p = NS). Mean systolic BPs were 113.8 mm Hg among current OC users and 111.2 mm Hg among nonusers (p = 0.078); diastolic BPs were 68.5 and 68.9, respectively (p = NS). These data indicate a greater than three-fold increase in PRS among current OC users compared to nonusers, with virtually identical PRA and PA levels. The data indicate that normotensive women using OCs maintain normal PRA and PA levels despite marked elevations in PRS.

Adult↗
PubMed1982

Hyperprolactinaemia in males with and without pituitary macroadenomas.

To ascertain whether in hyperprolactinaemic men pituitary macroadenomas represent the end stage of a disease process wherein the only early symptom is impotence, the features of 16 hyperprolactinaemic men with radiological evidence of pituitary macroadenomas were compared with those of 10 hyperprolactinaemic men without pituitary macroadenomas. All were impotent and 25 had low serum testosterone levels. The group with pituitary macroadenoma was older (48.1 vs 63.2 years) and had tolerated impotence for longer (10.4 +/- 6.0 vs 4.5 +/- 2.1 years). 6 of them had visual field defects (none in the other group), 14 had hypopituitarism (1 in the other group), and 14 were initially seen for problems other than sexual dysfunction (whereas all 10 without pituitary macroadenomas were seen primarily for evaluation of recent onset of impotence). In the macroadenoma group bromocriptine restored serum prolactin levels in 13 of the 16 and serum testosterone and potency in 5, whereas in the non-tumour group it restored serum prolactin levels in all 10 and serum testosterone and potency in 9.

Adenoma↗
PubMed1982

Bromocriptine reduces pituitary tumor size and hypersection. Requiem for pituitary surgery?

Twelve patients with pituitary tumor whose prior treatment included surgery and radiotherapy in four, surgery alone in four, radiotherapy alone in one, and none in three were studied. Nine had hyperprolactinemia, two had elevated serum growth hormones, and one had no pituitary hormone excess. Visual field defects were present in six. All had pituitary-gonadal insufficiency manifested as impotence or amenorrhea. All were tested with bromocriptine, 7.5 to 25 mg daily, and followed up for eight to 27 (mean 15) months. Serum prolactin levels decreased to normal in seven of nine patients. Serum growth hormone values were normalized in both acromegalics. When hormone levels were reduced to normal, pituitary tumor size decreased. Vision was restored to normal in five of six patients, including one patient with pituitary tumor but no pituitary hormone excess. Bromocriptine corrects the physiological defects associated with pituitary tumors that have been incompletely treated with surgery, radiotherapy, or both and may be a useful primary treatment for patients with pituitary tumors.

Adult↗
PubMed1979

Complete remission of acromegaly with medical treatment.

A 40-year-old patient with a ten-year history of acromegaly had persistent disease despite prior treatment with conventional pituitary radiotherapy and two transsphenoidal hypophysectomies. Initial evaluation showed characteristic acromegalic features, hypertension, amenorrhea, inappropriate diaphoresis, and poorly controlled diabetes mellitus despite isophane insulin suspension daily. Growth-hormone levels were high and did not suppress with glucose load. Treatment with bromocriptine was associated with prompt improvement in glucose intolerance, with elimination of insulin requirement within 72 hours of institutions of this therapy. Blood pressure normalized; inappropriate diaphoresis disappeared. Within three months ovulatory menses were noted to resume for the first time in ten years. There was progressive improvement in the soft-tissue changes of acromegaly. The growth-hormone levels fell within three hours after the first dose of bromocryptine and remained suppressed throughout her six-month course of therapy.

Acromegaly↗
PubMed1979

Bromocriptine and endocrine disorders.

Bromocriptine, a dopaminergic agonist, has been used to treat many endocrine disorders. In hyperprolactinemia associated with galactorrhea, amenorrhea, oligospermia, and impotence, bromocriptine reduces prolactin levels to normal and allows for satisfactory return of sexual and reproductive function in 90% of patients. In acromegaly, bromocriptine brings about subjective improvement in 75% of patients with reduction in growth-hormone levels to normal in 22% of patients. Bromocriptine has been used in premenstrual tension, functional infertility, Nelson's syndrome, and Cushing's disease with variable benefit. In low doses, side-effects are minimal. In higher doses, digital vasospasm and gastrointestinal bleeding have occurred. Although bromocriptine has been used in a wide variety of endocrine disorders, it appears to be most useful in treatment of male and female infertility associated with hyperprolactinemia.

Acromegaly↗
PubMed1978

Treatment of Cushing's syndrome with trilostane (WIN 24,540), an inhibitor of adrenal steroid biosynthesis.

Seven patients with Cushing's syndrome were treated with trilostane (WIN 24,540) 4 alpha,5-epoxy-17 beta-hydroxy-3-oxo-5 alpha-androstane-2 alpha-carbonitrile), an inhibitor of adrenal steroid biosynthesis. Trilostane treatment reduced steroid biosynthesis and it also improved biochemical manifestations of the disease in all of the patients treated. The average cortisol secretory rate decreased significantly with treatment, from 47.1 to 23.4 mg/24 h (P less than 0.005), and urinary 17-hydroxycorticosteroids decreased from 15.7 to 8.7 mg/24 h (P less than 0.01). Urinary free cortisol excretion decreased from 277 to 88 microgram/24 h (P less than 0.01), and 0800 h plasma cortisol levels declined from 25.0 to 12.0 microgram/dl (P less than 0.05). Conversely, dehydroepiandrosterone sulfate excretion in urine increased from 1.3 to 5.8 mg/24 h (P less than 0.0025) and in plasma increased from 162 mg/24 h (P less than 0.025). Plasma and urinary free dehydroepiandrosterone increased 2-fold. Urinary 17-ketosteroid excretion increased from 18 to 43 mg/24 h (P less than 0.001). A significant reduction in urinary excretion of tetrahydroaldosterone, tetrahydrodeoxycorticosterone, and 18-hydroxytetrahydrodeoxycorticosterone was observed with treatment. Inhibition of steroid biosynthesis was accompanied by a 2-fold increase in PRA and no change in serum cholesterol levels. Mean arterial blood pressure decreased with treatment from 109 to 97 mm Hg (P less than 0.005), and fasting blood sugar decreased from 117 to 98 mg/dl (P less than 0.005), accompanied by rise in plasma potassium levels from 3.8 to 4.3 milliequivalents/liter (P less than 0.025). Two patients on long term therapy also showed an improvement in clinical features of their disease. There were no significant treatment-related carcinoma, simultaneously producing both an excessive amount of cortisol and ACTH, is described. It is concluded that trilostane is an effective inhibitor of 3 beta-hydroxysteroid dehydrogenase enzyme system in human adrenal gland; it inhibits biosynthesis of cortisol and it is useful in the treatment of Cushing's syndrome.

17-Ketosteroids↗
PubMed1976

Galactorrhea-amenorrhea syndromes: etiology and treatment.

Fifteen patients with galactorrhea-amenorrhea syndromes were studied before, during, and after treatment with bromergocryptine. Galactorrhea and amenorrhea were noted after pregnancy (6 patients), after oral contraceptive therapy (5 patients), and in association with pituitary adenoma (4 patients). Before treatment prolactin values were elevated ranging from 27 to 125 ng/ml, while luteinizing hormone and progesterone levels failed to show ovulatory peaks or luteal phase progression. Eleven patients had luteinizing hormone-releasing hormone tests before therapy. Response was normal in 8, subnormal in 2 pituitary adenoma, and supranormal in 1 patient with premature ovarian failure. Treatment with bromergocryptine was associated with a lowering of serum prolactin, cessation of lactation in all, and return of ovulatory menses in 14 of 15 patients. All relapsed when therapy was discontinued. Four patients became pregnant while on therapy. Long-term bromergocryptine therapy is effective for all forms of galactorrhea-amenorrhea syndromes studied.

Adenoma↗
PubMed1976

Effect of dehydration and cardiac tamponade on superior mesenteric artery flow: role of vasoactive substances.

The role of serotonin, catecholamines, and angiotensin in the pathogenesis of mesenteric low flow states was investigated in anesthetized dogs by measurement of blood flows with electromagnetic flow meters. During dehydration or cardiac tamponade, a disproportionate decrease in superior mesenteric artery flow was demonstrated, compared with aortic flow, but renal artery flow was relatively better maintained. Depletion of serotonin and catecholamines by pretreatment with reserpine or blocking serotonin's action with methysergide did not alter the disproportionate reduction in mesenteric flow. Disproportionate superior mesenteric artery flow during dehydration and tamponade was associated with increased levels of circulating angiotensin and virtually was abolished by bilateral nephrectomy, by inhibition of enzymatic conversion of angiotensin I to II by Bothrops nonapeptide, and by competitive inhibition of angiotensin II with 1-sar, 8-ala angiotensin II. Exogenous angiotensin administered intravenously to dogs not protected by drug treatment disproportionately decreased superior mesenteric artery flow with less effect on renal artery flow. These results are compatible with the hypothesis that increased circulating levels of angiotensin during dehydration and tamponade contribute to the disproportionate reduction in superior mesenteric artery flow in the anesthetized dog.

Angiotensin II↗
PubMed1976

Renal trauma and hypertension: the role of renin.

Three patients developed hypertension following renal trauma. Trauma produced perinephric hematoma in two and renal artery thrombosis in one. Renal vein plasma renin activity (PRA) from the traumatized kidney was three to eight times greater than renal vein PRA from the untraumatized (contralateral) kidney. Peripheral PRA was elevated in all. A surgical operation lowered peripheral PRA to normal in all, but corrected hypertension in only two of three. Preoperative medical treatment with renin-suppressing pharmacologic agents correctly predicted this response to surgery. Postoperative renal vein PRA in the remaining hypertensive patient demonstrated that surgery successfully alleviated the abnormality in renin secretion. These studies suggest that excessive renin secretion initiate but other unidentified factors may contribute to the hypertension observed after renal trauma.

Adult↗