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Biomedical subjects

C Valverde

Publications and source records attributed to C Valverde.

15 recordsLinked to original sources
PubMed1991

Neuroendocrine regulation of adrenal 5'-monodeiodination during acute cold exposure in the rat. I. Effects of hypophysectomy.

Circulating levels of T4, T3, corticosterone, noradrenaline, and adrenaline, as well as 5'-monodeiodinase activity (5'-MA) were measured in control and hypophysectomized rats acutely exposed to cold environment (15-120 min, 4 C). In addition to the well known activation of the sympathoadrenomedullary system and the hypothalamic-pituitary-adrenal and-thyroid axes, cold exposure was followed by a rapid and sustained increase of 5'-MA in the hypothalamus, and a byphasic course of activation in the adrenal gland in control rats. The adrenal rapid activation (30 min) corresponded to the medulla and the slower activation (120 min) to the cortex. Both, the basal adrenal 5'-MA and the response to cold in adrenal and hypothalamus were 2-fold higher in hypophysectomized rats compared to control. The time course of enzyme activation in these structures suggests that: 1) organ-specific increases in 5'-MA may be associated to a simultaneous rise in their metabolic and/or functional activity, 2) the triggering mechanisms involves an immediate sympathetic signal activating the hypothalamic-adrenal medulla response and a pituitary signal eliciting a slower adrenocortical response, and 3) the compensatory sympathetic hyperactivity after panhypopituitarism contribute to enhance both the adrenal enzyme basal activity and the hypothalamic and adrenal hyperresponse to cold stress.

Adrenal Cortex↗
PubMed1989

[Demographic trends: birth spacing].

Two studies to measure children spacing in western metropolitan Santiago are compared. The first (1984-85) surveyed a sample of 687 mothers and the second 1,000. Deliveries took place at San Juan de Dios and Félix Bulnes hospitals (both state-finance) which provide medical care for medium and low income groups. Long spacing (5 years or more) accounted for the highest proportion of non-first born children (33.8% in 1984-85 with a significant increase to 40.1% in 1988) while short spacing (under 2 years) accounted for 19.2% in 1984-85 and 21.8% in 1988 (not significant). Mean birth weights were over 3,200 g in every spacing group. Despite the low illiteracy rate, predominant urban origin and having at least one child born before, high proportions of children were conceived despite the use of contraceptive measures (19.7% in 1984-85 and 22.5% in 1988). This contraceptive failure was less frequent among children born after longer spacings.

Birth Intervals↗
PubMed1977

[A test for acute hypocalcemia using swine and salmon calcitonin].

The production of acute hypocalcemia was investigated using either 80 U. MRC of salmon calcitonin or 160 1. mrc of pork calcitonin in 117 subjects (58 patients with Paget's disease, 22 with osteoporosis, 22 with Sudeck-Leriche algodystrophy and 15 control subjects). The results obtained with the two types of calcitonin did not differ. Induced acute hypocalcemia was more pronounced in patients with Paget's disease than in the other subjects studied. In patients with Paget's disease there were statistically significant correlations between the hypocalcemia produced and the initial levels of alkaline phosphatase and total 24 hours urinary hydroxyproline.

Acute Disease↗
PubMedDate not supplied

The importance of employing homologous serum free of thyronines in radioimmunoassays to assess circulating thyroid hormones in rainbow trout.

Although abundant, available information regarding the values of circulating thyronines in the rainbow trout is misleading and confusing. The present study demonstrates the importance of maintaining species serum-homology when measuring thyronines with RIA to avoid spurious results. The utilization of homologous (trout) serum free of thyronines in the standard curve allowed the standardization of accurate and specific radioimmunoassays to quantitate circulating T3 and T4 levels in 10 microliters of rainbow trout serum. Detection limit was 50 pg for both thyronines. Inter- and intra-assay coefficients of variation were minor to 10%. Mean values for T3 and T4 +/- SEM in the trout population studied (n = 34) were 23.6 +/- 1.2 and 12.0 +/- 2.3 ng/ml respectively. A positive and significant correlation (p < 0.005) between body weight and T3 was observed, confirming the active participation of this thyronine in growth processes.

Animals↗
PubMedDate not supplied

[Early introduction of dairy formulas in infant feeding].

Frequency, main features and factors associated to introduction of supplemental artificial milk formula at the first month of life were studied in 365 infants born from June 1st, through October 31, 1980, who were under control at a well baby clinic of Santiago, Chile, along years 1986 throughout 1987. By means of life-table analysis, time length of breast feeding was measured and compared in children with and without early formula introduction. In 22.5% of infants an artificial milk formula was given (82/365). In 80% of the cases (66/82) this was done upon instructions of health personnel on grounds of poor weight increase. Early introduction of formula negatively influenced duration of breast feeding which attained a median length of three months in artificially fed infant against ten months in those exclusively breast fed. Main features of infants and mothers prone to early formula introduction were maternal age 35 years or over, previous breast feeding shorter than six months, illegitimacy or first child, fourth or over in birth order, low birth weight and, or, hospital admission in the first four weeks of life. No influence was identified from educational level, of maternal work, desired or unwanted pregnancy, maternal nutritional status in the last three months of pregnancy, child spacing, type of delivery, sex and gestational age of the infants.

Age Factors↗