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Biomedical subjects

E del Pozo

Publications and source records attributed to E del Pozo.

At least 19 recordsLinked to original sources
PubMed1992

Dynamics of circulating osteocalcin in rats during growth and under experimental conditions.

Osteocalcin is the most abundant non-collagenous protein produced in the process of bone formation. A specific radioimmunoassay has been developed using a rabbit antiserum raised against osteocalcin extracted from rat bone. The sensitivity of the assay was tested in male and female rats under different experimental conditions: ovariectomy led to a mild increase in circulating osteocalcin (70.6 +/- 6.9 vs 51.6 +/- 6.3 ng/ml; p < 0.05) and deprivation of dietary calcium elevated plasma levels further (119 +/- 6.3 ng/ml; p < 0.01). As expected, pharmacological enhancement of bone turnover with calcitriol produced a significant increase in plasma osteocalcin (296 +/- 24.1 vs 89.5 +/- 5.1 ng/ml; p < 0.01), whereas prednisolone, a steroidal compound known to inhibit osteoid mineralization, significantly reduced circulating concentrations of this protein (70 +/- 7.4 vs 100 +/- 6.3 ng/ml; p < 0.05). Plasma kinetics recorded in female rats between birth and the 100th week revealed a highly significant (p < 0.001) elevation peaking at the third week (231 +/- 70.6 ng/ml) and slowly declining to reach values measured at birth (41.3 +/- 9.2 ng/ml) at the 16th week (47 +/- 4.6 ng/ml). Subsequently, a small but significant (p < 0.05) decline towards senescence was recorded. The osteocalcin surge preceded the period of rapid growth (weeks 3 to 11) estimated by vertebral length progression, showing a tendency to stabilize as growth spurt slowed down. A moderate but significant (p < 0.01) increment was observed after mating (87.8 +/- 5.1 vs 69.5 +/- 4.0 ng/ml). Although plasma osteocalcin remained stable during lactation, average levels were elevated in comparison with age-matched non-pregnant controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1979

Improved sexual function in male haemodialysis patients on bromocriptine.

The effect of bromocriptine on sexual activity was studied in male haemodialysis patients in a single-blind placebo controlled trial with random cross-over. At a dose of 2.5 mg bromocriptine twice day, plasma-prolactin concentrations were consistently reduced, while sexual function as assessed by a questionnaire was markedly improved. At the doses used, side-effects, particularly hypotension, were common, but bromocriptine helped to restore sexual function in dialysed patients.

Bromocriptine↗
PubMed1979

Prolactin. I. Mechanisms of control, peripheral actions and modification by drugs.

The role of neurotransmitters in the release of prolactin (PRL) is reviewed. Special attention is paid to dopamine (DA) as the possible prolactin-inhibiting factor (PIF). Among other agents, estrogens alone can act directly on the pituitary galactotropes without involving hypothalamic factors. Peripherally, in addition to its stimulatory action on mammary tissue, PRL exerts a permissive role on ovarian steroidogenesis. A possible physiological action of this hormone on the regulation of adrenal function remains uncertain. The secretory rhythms of PRL are described and the mechanisms involved are discussed. A number of drugs can modify the secreting pattern of PRL mainly by acting on the dopaminergic control mechanisms. The usefulness of such agents in the clinical evaluation of galactotrope cell function is reviewed.

Adolescent↗
PubMed1979

Prolactin and deficient luteal function.

The possibility of prolactin-dependent subfertility was investigated in a group of 8 women, with luteal insufficiency exhibiting moderately elevated plasma prolactin (PRL) levels and/or galactorrhea. Another group of 10 normal women volunteers served as the control group. A "luteal index" was elaborated by integration of the area below the curve of plasma progesterone (P) values recorded throughout the postovulatory period. The calculated index for normal women was 177 +/- 35 (SD) expressed as [(ng/ml) x time], and the value of 107 (--2 SD) was adopted as the lower limit of normality (97.5% confidence limit). All 8 patients had luteal indexes (range 20--105) below the established limit. Therapy with bromocriptine (CB 154), 5 mg/day, suppressed PRL to normal levels and prolonged the postovulatory hyperthermic phase in 6 out of 8 women. This was accompanied by an improvement in the luteal index, and 5 women conceived. It is concluded that prolactin may interfere with normal progesterone synthesis by the corpus luteum, as demonstrated by the prompt restoration of fertility by bromocriptine treatment in women with regular cycles and inadequate luteal function.

Adult↗
PubMed1978

Inhibitory effect of guanfacine, a central alpha-adrenoceptor agonist, on prolactin secretion stimulated by insulin-induced hypoglycemia.

In six normal male volunteers oral administration of an alpha-receptor agonist, guanfacine (1 mg/q.i.d. for 4 days), had no effect on PRL release induced by 5 mg metoclopramide iv. The same treatment with quanfacine in six other normal subjects significantly reduced PRL secretion stimulated by insulin-induced hypoglycemia (P less than 0.05). These results suggest that an adrenergic pathway, hypothalamic or extrahypothalamic, might be involved in the inhibitory control of PRL secretion.

Adrenergic alpha-Agonists↗
PubMed1976

Lack of effect of acute prolactin suppression on renal water sodium and potassium excretion during sleep.

The possible role of endogenous prolactin (hPRL) in the regulation of renal water, Na and K excretion during sleep was tested in a group of 10 healthy female volunteers. Plasma hPRL and total urinary Na and K excretion were measured at 2- and 4-hourly intervals, respectively, in the control period and after prolactin inhibition with bromocriptin. Despite adequate prolactin suppression, no significant changes were observed in the nyctohemeral excretion rhythms of water, Na and K, suggesting that endogenous prolactin is not instrumental in the control of these parameters.

Adult↗
PubMed1975

Lack of action of prolactin suppression on the regulation of the human menstrual cycle.

Bromocriptin (CB 154) has been found to suppress established lactation at a time when human plasma prolactin (HPRL) concentrations have already returned to the nonpregnant range. This action is due to inhibition of prolactin from the pituitary. It was then thought that a similar degree of inhibition induced during the menstrual cycle may help to uncover other possible biological actions of prolactin. In an attempt to elucidate this question eight breast-feeding mothers and seven normally menstruating volunteers underwent treatment with CB 154, including blood sampling during a sleep period. The dosage was 1 mg., three times daily, for 14 days in the first group and for a whole cycle in the normal volunteers. A control cycle preceded drug administration in the latter group. Prolactin (HPRL), growth hormone (HGH), luteotropin (LH), progesterone (PG), and estradiol (E2) were estimated (mean +/- standard error) along the menstrual cycles in the normal volunteers. HPRL and milk volumes were measured in the breast-feeding women in the base-line period and during treatment. In the postpartum group, basal HPRL had already reached normal levels prior to therapy (10.8 +/- 1.0 ng. per milliliter) and was significantly (p less than 0.002) depressed to 3.7 +/- 0.4 ng. per milliliter by CB 154. This degree of inhibition was effective in suppressing lactation within 24 to 48 hours in all of the subjects in that group. The fall in plasma HPRL from 9.5 +/- 1.5 ng. per milliliter to 3.2 +/- 0.2 ng. per milliliter observed in the normally menstruating women was similar to the one recorded in the breast-feeding group, but the sequence of hormonal changes during the menstrual cycle was not altered by treatment. The overnight study ensured around-the-clock prolactin inhibition. Results indicate no action of prolactin in the regulation of the human menstrual cycle at levels of inhibition at which a biological action of this hormone is clearly suppressed.

Adult↗
PubMed1975

Comparative kinetics of 45Ca and 89Sr in chronic uremic syndrome in the rat.

In rats a chronic uremic syndrome was induced by 5/6 resection and subsequent irradiation of the kidneys. After 5 weeks 45Ca and 89Sr were injected simultaneously, and the different metabolic handling of the two elements was determined applying an open two-compartment model of Calcium kinetics. The uremic animals were compared with two groups of rats which were pairfed, and fed ad libitum, respectively. Besides an elevenfold faster urinary excretion when calculated with Sr, and which was reduced to about one half in the uremic rats, a significant discrimination by bone in favour of Ca was found, with a rather stable factor of 1.2 in the three groups. This is considered to evidence that urinary excretion and bon uptake of Sr are independent processes.

Animals↗
PubMed1975

Suprasellar disturbance in the syndrome of fertile eunuchoidism: case report.

A case of fertile eunuchoidism is presented. The diagnosis was established on the basis of low androgen secretion in the presence of active spermatogenesis, increase in testosterone output after gonadotrophin stimulation, and adequate peripheral response to exogenous testosterone. Resistance to clomiphene stimulation but normal pituitary response to LH-RH was elicited indicating a suprasellar disturbance as the cause of the disorder.

Adult↗