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Biomedical subjects

C Castillo

Publications and source records attributed to C Castillo.

At least 109 records · Page 6Linked to original sources
PubMed1995

A comparative study of the effects of some 5-HT1A receptor agonists on the blood pressure of pithed rats.

The intention of this study was to supply additional information about direct effects of the 5-HT1A receptor agonist indorenate on the arterial blood pressure. The effects of indorenate were compared with those of buspirone and ipsapirone (all selective 5-HT1A agonists) on the blood pressure of pithed rats. These compounds increased the blood pressure in a dose-dependent fashion. The effects of either ipsapirone or buspirone were clearly inhibited with 100 micrograms/kg of prazosin (selective alpha 1-adrenoceptor antagonist), whereas 1 mg/kg of this blocker elicited only a mild inhibition of the pressor effect of indorenate. Pindolol (100 micrograms/kg; a beta-adrenoceptor and 5-HT1 receptor blocker) was unable to modify the effects of all the 5-HT1A agonists tested. In addition, the 5-HT2 receptor and weak alpha 1-adrenoceptor blocker ketanserin (10-100 micrograms/kg) antagonized the pressor effect of indorenate. Nevertheless, only a mild inhibition was observed in the case of both ipsapirone and buspirone. On the other hand, the latter drugs diminished the blood pressure of pithed rats intravenously infused with norepinephrine, but indorenate was inactive. However, in rats infused with quipazine, all the 5-HT1A agonists failed to reduce blood pressure. These results indicate that buspirone and ipsapirone behaved as partial alpha 1-adrenoceptor agonists. Furthermore, the results show that indorenate-elicited pressor effects are probably due to stimulation of 5-HT2 receptors. Thus, unlike ipsapirone and buspirone, indorenate did not show conclusively activity related with alpha 1-adrenoceptors.

5-Methoxytryptamine↗
PubMed1995

[Breast feeding and the nutritional status of Chilean children].

The purpose of this work was to describe the diet of children under 18 months of age and its relationship to nutritional status. For this purpose, in 1993 a prevalence study was carried out on children who received care from the National Health Services System of Chile. The Chilean public health system provides care to 75% of children under 6 years of age and especially to children of families in the lower strata of income distribution in the country. Participants in the study were 9330 children under 18 months old who were randomly selected from 102 of the 320 urban clinics throughout the country. The type of food these infants had received the day prior to the interview (breast milk exclusively, breast milk plus solid food, formula exclusively, formula plus solid food) and their nutritional status relative to the standards of the National Center for Health Statistics (United States of America) and of WHO were determined. Children with z values for weight-for-age between -1.0 and -2.0 standard deviations were considered at risk for malnutrition, and those with z values under 2 standard deviations were classified as malnourished. The prevalences of exclusive breast-feeding at the first, third, and sixth months of life were 86.5%, 66.7%, and 25.3%, respectively. Some 12.1% of the participants showed low weight for age; 30.7%, low height for age; and 35.7%, overweight. The magnitude of weight-for-age deficiency was 1.2 to 5 times greater among children who were fed milk substitutes than among those who received breast milk. Breast-feeding also had a positive effect on height. These results confirm the benefits of exclusive breast-feeding until 6 months of age, the need to supplement the child's diet with solid food after that age, and the breast-feeding's protective effect on the nutritional status of children of all the ages studied.

Body Height↗
PubMed1995

[Malnutrition of the pregnant woman: an overestimated problem?].

The aim of this work was to compare the nutritional classification of pregnant women and their predictive value for low birth weight, using the criteria of the Ministry of Health (Rosso-Mardones curves) with the curves developed at the Department of Nutrition of the Faculty of Medicine and the body mass index. One thousand eight hundred four pregnant women of the Metropolitan Region, that were devoid of factors affecting birth weight, were studied retrospectively. Initial and final nutritional status was calculated according to the three criteria in study. Results showed that 47 to 75% of women classified as undernourished using Rosso-Mardones curves, were normal according to the curves of the Department of Nutrition and body mass index. Rosso-Mardones curves had the lower predictive value, relative risk and risk attributable to maternal nutritional deficit, for low birth weight. Also these curves showed a higher of obesity and a low predictive value for macrosomia. It is concluded that the curves used by the Ministry of Health must be revised.

Birth Weight↗
PubMed1995

Changes in endothelium-dependent vascular responses associated with spontaneous hypertension and age in rats.

The aim of this study was to investigate if the endothelium-dependent relaxation and the inhibitory effect of endothelium against vasoconstrictor stimuli are reduced by aging and hypertension in rat aorta. Both relaxation and isometric contraction of intact and denuded aortic rings from spontaneously hypertensive rats (SHR) of 7-9, 12-18, 28-36 and more than 70 weeks old and from age-matched Wistar-Kyoto rats (WKY) were measured in parallel. An age-related decrease of endothelium-dependent relaxation to acetylcholine was found, which was greater in arteries from SHR (p < 0.05). Indomethacin normalized the endothelium-dependent relaxations in aortic rings from either old or hypertensive rats. Relaxations elicited by nitroglycerin were slightly enhanced with age in both WKY and SHR (p < 0.05). Moreover, endothelium removal increased responsiveness to indanidine and to 5-hydroxytryptamine (5-HT). Endothelium-dependent inhibition on the contraction decreased with aging (to a greater extent in SHR). These results indicate that aging and hypertension are associated with a decrease in the endothelium-dependent responses. Endothelium-dependent relaxations of aortae from old normotensive and hypertensive rats were impaired by the production of a cyclooxygenase-derived contractile factor. However, the higher response to nitroglycerin suggests a lesser production of endogenous nitric oxide by endothelial cells.

Aging↗
PubMed1994

Expression of sodium channels with different saxitoxin affinity during rat forebrain development.

This work characterizes the development of the saxitoxin (STX)-sensitive Na+ channels from rat whole forebrain between embryonic day 15 (E15) and postnatal day 90 (P90), both with binding studies and with single channel studies. The Na+ channel total mRNA and the individual mRNAs encoding Na+ channels I, II and III were also determined. The total STX binding rose about 40-fold from E15 to reach a plateau at P30 and its temporal course correlated with the expression of Na+ channel total mRNA. Low affinity and high-affinity STX binding sites, predominant in embryonic and postnatal forebrains, respectively, were found. The single channel studies of batrachotoxin-modified channels also revealed two main populations. In E15 only low-affinity channels (KD = 32.7 nM; 200 mM NaCl) and in P30 only high affinity ones (KD = 1.6 nM) were present. At P0 channels with intermediate affinity (KD range 3-34 nM) were observed. The increase in affinity was due to a gradual increase in the STX association rate.

Animals↗
PubMed1994

Interstitial insulin concentrations determine glucose uptake rates but not insulin resistance in lean and obese men.

Insulin action and obesity are both correlated with the density of muscle capillary supply in humans. Since the altered muscle anatomy in the obese might affect interstitial insulin concentrations and reduce insulin action, we have cannulated peripheral lymphatic vessels in lean and obese males, and compared peripheral lymph insulin concentrations with whole body glucose uptake during a euglycemic, hyperinsulinemic clamp. Lymph insulin concentrations in the lower limb averaged only 34% of arterial insulin concentrations during 150 min of insulin infusion. Obese subjects had the highest arterial (P < or = 0.0001) and lymph insulin (P < 0.005) concentrations, but the lowest glucose uptake rates (P < 0.002). In contrast to the initial steep rise then plateau of arterial insulins, both lymph insulin and whole body glucose uptake rates rose slowly and did not consistently reach a plateau. In each individual, the glucose uptake closely correlated with peripheral lymphatic insulin concentrations (mean r2 = 0.95). The coupling between glucose uptake and lymph insulin (glucose uptake/pmol insulin) was much steeper in lean subjects than in the obese (P < or = 0.0001). These results indicate that even if insulin diffusion into tissues is rate limiting for insulin action, a tissue defect rather than an insulin diffusion defect causes insulin resistance in obese subjects.

Adult↗
PubMed1994

[Iron nutritional status in pregnant adolescents at the beginning of gestation].

The frequency of anemia and iron nutrition deficiency was assessed in 342 low socioeconomic level pregnant teenagers at entry to prenatal care in 5 outpatient clinics from a South Orient area of Santiago Chile. According to the Center for Disease Control Criteria, 1.2% of women had iron deficiency anemia. Iron stores were insufficient (defined as a serum ferritin lower than 20 g/L) in 55% for women and depleted (serum ferritin lower than 10 g/L) in 21%. Women with more than 14 weeks of gestation had lower packed red cell volumes, hemoglobin, mean corpuscular volumes and ferritin levels than women with less than 14 of gestation. It is concluded that the prevalence of iron deficiency anemia is lower than that predicted for a highly vulnerable group but the high frequency of low iron stores should encourage the use of iron supplementation in these teenagers.

Adolescent↗
PubMed1994

[Acute extra-axial hematoma post-traumatic of the clivus].

Magnetic Resonance Imaging (MRI) has amply shown its usefulness for the evaluation of traumatic cranio-encephalic lesions, particularly those involving the posterior fossa, due to the absence of bone artifacts, the availability of multiplanar sections and the greater sensitivity as regards Computerized Tomography (C. T.). We present an MRI examination of an extra-axial hematoma of the clivus in a child with head trauma, not visible on C. T. scans.

Brain Injuries↗
PubMed1993

Pharmacological evidence for interactions between 5-HT1A receptor agonists and subtypes of alpha 1-adrenoceptors on rabbit aorta.

This study was designed to determine if alpha 1-adrenoceptors are involved in the vascular responses to 5-HT1A receptor agonists. Buspirone (3.1 x 10(-7)-3.1 x 10(-5) M) and 8-hydroxy-2(di-N-propylamino)tetralin (8-OH-DPAT; 3.1 x 10(-6)-10(-4) M) elicited contractions of rabbit aorta rings which were blocked by prazosin (10(-9)-5.6 x 10(-9) M), but which were unaffected by reserpine pretreatment (1 mg/kg i.p.). 5-Methylurapidil (10(-7) and 10(-6) M) blocked contractions elicited by 8-OH-DPAT and by buspirone, whereas chloroethylchonidine (10(-5) and 10(-4) M) inhibited only the effect of buspirone. In addition, these 5-HT1A receptor agonists relaxed arteries precontracted with alpha-adrenoceptor agonists in a similar range of concentrations in which they elicited contraction. Moreover, 8-OH-DPAT and buspirone protected the alpha-adrenoceptors from the irreversible blockade provoked by phenoxybenzamine (10(-7) M), as judged by the norepinephrine contraction and stimulated phosphatidylinositol labeling. According to these results the contractile and relaxant effects elicited by 5-HT1A receptor agonists are a consequence of a direct interaction with alpha 1-adrenoceptors. The contraction elicited by 8-OH-DPAT may be mediated by alpha 1A-adrenoceptors, whereas both alpha 1A- and alpha 1B-adrenoceptors may mediate the effect of buspirone in rabbit aorta.

Adrenergic alpha-Agonists↗
PubMed1993

Flunitrazepam consumption among heroin addicts admitted for in-patient detoxification.

The use of benzodiazepines among 973 heroin addicts admitted for inpatient detoxification over a 10-year period was assessed in a cross-sectional study. A total of 780 (80.2%) patients had a history of benzodiazepine use; 666 (68.5%) were consuming benzodiazepines at the time of admission and 419 (43.1%) on an almost daily basis. Seventy-five (7.7%) patients fulfilled criteria for sedative-hypnotic abuse or dependence. Consumption of benzodiazepines began after subjects had become addicted to heroin. Flunitrazepam was ranked first by 68.4% of patients, followed by clorazepate (13%), and diazepam (12.4%). The prevalence of benzodiazepine use, in particular flunitrazepam, among heroin addicts is very high. Specific abuse liability studies are needed to determine whether pharmacologic reasons exist to explain heroin addicts' preference for this compound.

Anti-Anxiety Agents↗
PubMed1993

Consumption of buprenorphine and other drugs among heroin addicts under ambulatory treatment: results from cross-sectional studies in 1988 and 1990.

We assessed the prevalence of consumption of buprenorphine and other drugs among heroin addicts under ambulatory treatment in two cross-sectional studies conducted in 1988 (188 subjects) and in 1990 (197 subjects). Patients were enrolled in one of three different programmes: methadone maintenance programme (MMP), antagonist maintenance programme (AMP) and drug-free programme (DFP). Information given by participants was compared with results of urine screening for drugs. Urine samples were tested using enzyme immunoassay for the detection of heroin, cocaine, dextropropoxyphene, cannabis and benzodiazepines, and radioimmunoassay for buprenorphine. Sixty-six percent of patients in 1988 and 71% of patients in 1990 reported having consumed buprenorphine at some time during their history of drug dependence (period prevalence) and 5.9% and 6.1%, respectively, tested positive to the drug (point prevalence). In over 70% of these patients consumption was by the intravenous route. Consumption of cannabis, cocaine and benzodiazepines was also very high in the study population. Overall, patients in the DFP group consumed the largest number of the drugs tested, while those in the AMP group consumed the smallest number. Abuse of buprenorphine could be more widespread than previously reported.

Adult↗