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L Castro

Publications and source records attributed to L Castro.

At least 37 records · Page 2Linked to original sources
PubMed2000

Central 5-HT(4) receptors and drinking behavior.

The aim of the present study was to investigate the effect of acute third ventricle injections of two different 5-HT(4) receptor antagonists, GR 113808 and SB 204070, on water intake in different situations. Injections of 80 nmol/rat of both GR 113808 and SB 204070 were unable to modify water intake in normohydrated rats. Pretreatment with GR 113808 (40 and 80 nmol/rat) and SB 204070 (80 and 160 nmol/rat) blunted water intake after third ventricle injections of angiotensin II (9.6 pmol/rat) compared to saline-pretreated controls. Pretreatment with 80 nmol/rat of both antagonists potentiated drinking induced by third ventricle injections of carbachol (11.0 nmol/rat) compared to saline-pretreated control. In all doses employed, none of the compounds was able to modify water intake in dehydrated rats. A separate control test using one-bottle taste aversion paradigm indicated that the reduction in water intake observed in some of the present experiments could not be attributed to a drug-induced malaise. It is suggested that central 5-HT(4) receptors exert a dualistic role on the control of water intake potentiating angiotensin II-induced drinking and inhibiting thirst induced by central cholinergic activation

Animals↗
PubMed2000

Inter- and intraspecific sexual discrimination in the flour beetles Tribolium castaneum and Tribolium confusum.

In Tribolium castaneum (CS) and T. confusum (CF), intra- and interspecific rates of homosexual mounting have been measured. The intraspecific results are compatible with the hypothesis of both species being sexually indiscriminate. However, the CF intraspecific rates were very high (35%-53% of mountings were homosexual), suggesting a lower sexual attractiveness, or a stronger rejection to being mounted, of CF females relative to conspecific males. CS males discriminate between species but, in interspecific contacts, preferentially mounted CF males rather than CF females. CF males do not discriminate between species, but the loss of sexual attractiveness of CF females, or their rejection to being mounted, may act as a precopulatory isolation mechanism.

Animals↗
PubMed2000

Maternal deaths in an urban perinatal network, 1992-1998.

OBJECTIVE: The object of this study was to use an in-depth peer-review process to determine the maternal mortality ratio at a single urban perinatal center and to identify factors associated with fatal outcomes to elucidate opportunities for preventive measures to reduce the maternal mortality ratio. STUDY DESIGN: Between 1992 and 1998 all maternal deaths occurring within our perinatal network were identified. A peer-review committee was established to review all available data for each death to determine the underlying cause of death, whether it was related to pregnancy, and whether the death was potentially preventable. RESULTS: There were 131,500 births and 42 maternal deaths, for a maternal mortality ratio of 31.9 maternal deaths per 100,000 live births. The adjusted pregnancy-related maternal mortality ratio was 22.8 maternal deaths per 100,000 live births, with 37% of those deaths (11/30) deemed potentially preventable and a provider factor cited in >80% of these. Pulmonary embolus and cardiac disease together accounted for 40% of the pregnancy-related deaths. CONCLUSION: Local maternal mortality ratios identified through a peer-review process indicate that the magnitude of the problem is much greater than is recognized through national death certificate data. The high proportion of potentially preventable maternal deaths indicates the need for improvement in both patient and provider education if we are to reduce the maternal mortality ratio to 3.3 maternal deaths per 100,000 live births, the stated national health goal of Healthy People 2000.

Female↗
PubMed2000

Esophageal reconstruction surgery in oncologic patients: determination of gastric emptying time.

All parts of the gastrointestinal tract are accessible for study using nuclear medicine techniques. We have studied the effect of esophageal reconstruction surgery, in different periods of time, after surgical procedure. Oncologic patients (19) were evaluated after esophageal reconstruction surgery with gastric (group II - 14 patients) or colonic tube (group III - 5 patients) and they were compared with 15 healthy volunteers (group I). Gastric emptying was performed in the same subjects using solid food (egg sandwich) labeled with 99mTc-phytate. In emptying gastric studies, the mean (T1/2) of the patients was much faster than those of the control (p<0.05) when 1/3 distal tube was considered as stomach. However, there was no difference between the T1/2 of group II and group III. We concluded that this nuclear medicine method could be useful in the monitoring the surgical reconstruction of the esophagus.

Adenocarcinoma↗
PubMed1999

Central administration of zinc increases renal sodium and potassium excretion in rats.

The aim of the present study was to investigate the effect of acute third ventricle injections of zinc on the brain control of renal sodium and potassium excretion. Adult Wistar male rats received third ventricle injections of zinc acetate in three different doses (0.03, 0.3 and 3.0 nmol/rat). Third ventricle administration of zinc acetate provoked a significant intensification of natriuresis and kaliuresis as compared to sodium acetate-treated controls. When rats were pretreated with losartan, a selective angiotensin II AT1 receptor antagonist (10.8 nmol/rat into the third ventricle 10 min before central zinc injection) the increase in both natriuresis and kaliuresis was abolished. Furthermore, pretreatment with gadolinium, a calcium channel blocker (0.3 nmol/rat into the third ventricle 20 min before central zinc injection), also blunted the increase in renal sodium and potassium excretion seen in animals receiving zinc alone. In a group of rats receiving the same water load used in the previous experiments, the injection of zinc acetate into the third ventricle (3.0 nmol/rat) did not modify arterial blood pressure. It is suggested that zinc in the central nervous system may be involved in the control of renal sodium and potassium excretion by a mechanism unrelated to blood pressure increase. It is also shown that both natriuretic and kaliuretic actions of zinc depend on AT1 receptor activation. Whatever should be the mechanism(s) related to the central effects of zinc here evidenced, the functional integrity of calcium channels is required.

Angiotensin II↗
PubMed1999

Idiopathic polyhydramnios and perinatal outcome.

OBJECTIVE: The aim of this study was to determine whether there is any association between idiopathic polyhydramnios and adverse perinatal outcome. STUDY DESIGN: One hundred fifty-one consecutive women with singleton pregnancies complicated by idiopathic polyhydramnios (amniotic fluid index >24 cm) who were delivered at our institution during an 18-month period (December 1996-May 1998) were studied. Outcome measures studied included preterm delivery (<37 weeks' gestation), low birth weight (<2500 g), macrosomia (>4000 g), malpresentation at delivery, rate of cesarean delivery, Apgar score at 5 minutes <7, admission to the neonatal intensive care unit, and perinatal death. These findings were compared by means of the chi(2) test with those of 302 matched control subjects with normal amniotic fluid volume (<24 cm). RESULTS: Among pregnancies complicated by idiopathic polyhydramnios we did not observe any increases in preterm deliveries, low birth weight, low Apgar scores at 5 minutes, neonatal intensive care unit admissions, or perinatal mortality rate. However, idiopathic polyhydramnios was associated with significantly higher rates of malpresentation, macrosomia, and primary cesarean delivery. CONCLUSION: In contrast to previous reports that polyhydramnios related to specific causes (congenital anomalies, diabetes mellitus, isoimmunization) is associated with adverse perinatal outcomes, such as prematurity, low birth weight, and perinatal death, idiopathic polyhydramnios is not associated with higher rates of these traditional measures of poor outcome.

Apgar Score↗
PubMed1999

Zinc and water intake in rats: investigation of adrenergic and opiatergic central mechanisms.

We have demonstrated that central administration of zinc in minute amounts induces a significant antidipsogenic action in dehydrated rats as well as in rats under central cholinergic and angiotensinergic stimulation. Here we show that acute third ventricle injections of zinc also block water intake induced by central ss-adrenergic stimulation in Wistar rats (190-250 g). Central inhibition of opioid pathways by naloxone reverses the zinc-induced antidipsogenic effect in dehydrated rats. After 120 min, rats receiving third ventricle injections of isoproterenol (160 nmol/rat) exhibited a significant increase in water intake (5.78 +/- 0.54 ml/100 g body weight) compared to saline-treated controls (0.15 +/- 0.07 ml/100 g body weight). Pretreatment with zinc (3.0, 30.0 and 300.0 pmol/rat, 45 min before isoproterenol injection) blocked water intake in a dose-dependent way. At the highest dose employed a complete blockade was demonstrable (0.54 +/- 0.2 ml/100 g body weight). After 120 min, control (NaAc-treated) dehydrated rats, as expected, exhibited a high water intake (7.36 +/- 0.39 ml/100 g body weight). Central administration of zinc blocked this response (2.5 +/- 0.77 ml/100 g body weight). Naloxone pretreatment (82.5 nmol/rat, 30 min before zinc administration) reverted the water intake to the high levels observed in zinc-free dehydrated animals (7.04 +/- 0.56 ml/100 g body weight). These data indicate that zinc is able to block water intake induced by central ss-adrenergic stimulation and that zinc-induced blockade of water intake in dehydrated rats may be, at least in part, due to stimulation of central opioid peptides.

Adrenergic beta-Agonists↗
PubMed1999

Central lead administration inhibits water intake and sodium appetite in rats.

We have demonstrated that acute third ventricle injections of lead acetate (PbAc) exert a powerful antidipsogenic effect and induce a significant increase in renal sodium excretion. In the present study we confirm the antidipsogenic effect of lead and demonstrate that central administration of this metal, in minute amounts, significantly reduces salt intake both during dehydration and after central angiotensinergic stimulation. Adult male Wistar rats had the third ventricle cannulated seven days before the experiments. During this period they had free access to distilled water and hypertonic saline solution (1.5%). After a 24-h period of fluid deprivation, experimental animals received third ventricle injections of PbAc (0.3, N = 8 and 3.0 nmol/rat, N = 14) while controls received sodium acetate (NaAc; 3.0 nmol/rat, N = 10). Rats treated with PbAc at the highest dose showed a significant reduction (P<0.05) both in water and hypertonic saline intake when compared to controls. When the effect of lead administration on angiotensin II-induced water and salt intake was studied, normohydrated animals received third ventricle injections of angiotensin II (9.6 nmol/rat) after pretreatment with 3.0 nmol/rat of PbAc (experimental group, N = 10) or NaAc (controls, N = 8). The group pretreated with PbAc presented a significant reduction (P<0.05) in both water and salt intake compared to controls. Thus, this study confirms the antidipsogenic effect of central lead injections and demonstrates that the presence of lead in the brain exerts a significant inhibition of sodium appetite.

Angiotensins↗
PubMed1998

Central lead administration induces natriuretic and kaliuretic effects in rats.

The aim of the present experiments was to discern whether central acute lead injections affect brain control of renal function. Adult Wistar male rats received third-ventricle injections of lead acetate in three different doses (0.03, 0.3, and 3.0 nmol/rat). Lead acetate induced a significant increase in renal excretion of sodium and potassium. Pretreatment with losartan, a selective angiotensin II AT1 receptor antagonist (10.8 nmol/rat into the third ventricle 10 min before central lead injection), inhibits lead-induced natriuretic and kaliuretic effects. In addition, pretreatment with gadolinium, a calcium-channel blocker (0.3 nmol/rat into the third ventricle 20 min before central lead administration), reversed the increase in renal excretion of sodium and potassium provoked by central lead administration. Taken together, the data presented here suggest that lead injected into the third ventricle increases renal excretion of sodium and potassium by a mechanism that depends on the functional integrity of central angiotensin II AT1 receptors and calcium channels.

Angiotensin II↗
PubMed1998

Conceptual Capacity to Categorize and the Evolution of Altruism.

The conceptual capacity to categorize and consequently the ability to approve or reprove the one's and other's behavior allows the appearance of individuals with a new type of cooperative behavior that we have called "Assessor". The Assessor individual, if the partner behaves in a selfish way, reproves and penalizes this behavior changing his initial cooperation into defect. The reprobation permits that Assessor individuals, through simple observation, inhibit their altruistic behavior towards individuals whose selfish behavior has already been reproved, without having to interact with them. The evolutionary properties of Assessor behavior are analysed using the model of the iterated prisoner's dilemma where Assessor individuals compete with "always defect" individuals. The results are compared with those obtained, in the same circumstances, by other cooperative behaviors such as "always cooperate", "Tit-for-Tat" and "Observer-Tit-For-Tat". It is shown that in all situations Assessor is evolutionarily stronger than Tit-for-Tat when both face ALL D. It is also advantageous with respect to Observer-Tit-For-Tat in those situations that favor the evolution of reciprocal altruism "Tit-for Tat".Copyright 1998 Academic Press Limited

Journal Article↗
PubMed1998

Natriuretic and kaliuretic effects of central acute cadmium administration in rats.

We studied the acute effects of cadmium third ventricle injections on renal excretion of water, sodium and potassium in rats previously submitted to an oral water load equivalent to 10% of their body weight. Injections of cadmium chloride (0.03, 0.3, and 3.0 nmol/rat) significantly increased sodium and potassium renal excretion without changing urine flow. Pretreatment with losartan, an angiotensin II AT1 receptor antagonist (10.8 nmol/rat into the third ventricle 10 min before central cadmium administration) inhibits the natriuretic effect of this metal, being unable to reverse its kaliuretic effect. Pretreatment with gadolinium, a calcium-channel blocker (0.3 nmol/rat into the third ventricle 20 min before central cadmium administration) abolishes both the natriuretic and the kaliuretic response of cadmium. The data clearly show that cadmium injections into the third ventricle disturb central regulation of renal function leading to an increased renal loss of sodium and potassium. It is also evident that the natriuretic action of the metal depends on an increase in brain angiotensin II release. Also, the functional integrity of calcium channels is required for the expression of both the natriuretic and the kaliuretic effects of the metal.

Angiotensin Receptor Antagonists↗
PubMed1998

Opiatergic participation in the thirst-inhibiting effect of acute third ventricle injections of cadmium (Cd2+) and lead (Pb2+).

We have previously demonstrated that acute third ventricle injections of both lead and cadmium prevent the dipsogenic response elicited by dehydration or by central injections of dipsogenic agents such as angiotensin II, carbachol and isoproterenol in rats. We have also shown that the antidipsogenic action of cadmium may be due, at least in part, to activation of thirst-inhibitory central serotonergic pathways. In the present paper we show that in Wistar male rats the antidipsogenic effect of both lead acetate (3.0 nmol/rat) and cadmium chloride (3.0 nmol/rat) may be partially dependent on the activation of brain opiatergic pathways since central injections of naloxone (82.5 nmol/rat), a non-selective opioid antagonist, blunt the thirst-inhibiting effect of these metals. One hundred and twenty minutes after the second third ventricle injections, dehydrated animals (14 h overnight) receiving saline + sodium acetate displayed a high water intake (7.90 +/- 0.47 ml/100 g body weight) whereas animals receiving saline + lead acetate drank 3.24 +/- 0.47 ml/100 g body weight. Animals receiving naloxone + lead acetate drank 6.94 +/- 0.60 ml/100 g body weight. Animals receiving saline + saline drank 8.16 +/- 0.66 ml/100 g body weight whilst animals receiving saline + cadmium chloride drank 1.63 +/- 0.37 ml/100 g body weight. Animals receiving naloxone + cadmium chloride drank 8.01 +/- 0.94 ml/100 g body weight. It is suggested that acute third ventricle injections of both lead and cadmium exert their antidipsogenic effect by activating thirst-inhibiting opioid pathways in the brain.

Animals↗
PubMed1997

Examination of changes in interpersonal stress as a factor in disease exacerbations among women with rheumatoid arthritis.

OBJECTIVE: This study examined the effects of change in interpersonal stress on disease activity among 41 women with rheumatoid arthritis (RA). METHODS: Measures of everyday stressful events and perceived stress were collected weekly for twelve weeks and related to disease activity in a series of pooled time-series regression analyses. RESULTS: Increases in the number of interpersonal stressors in the same week and one week prior were associated with increases in disease activity. Pain from joint tenderness also was significantly related to a decrease in stressful events one week later. A subgroup of 20 patients showed a significant increase in interpersonal stress from baseline during the course of the study. For this group, significant elevations in DR + CD3 cells, sIL-2R, clinician's rating of disease, and self-reports of joint tenderness were found during the week of increased interpersonal stress. CONCLUSIONS: Interpersonal stress appears to be associated with increases in disease activity among RA patients.

Adult↗
PubMed1997

Lead (Pb2+) and cadmium (Cd2+) inhibit the dipsogenic action of central beta-adrenergic stimulation by isoproterenol.

We have previously demonstrated that acute third ventricle injections of both Pb2+ and Cd2+ impair the dipsogenic response elicited by three different situations: dehydration and central cholinergic or angiotensinergic stimulation. beta-Adrenergic activation is part of the multifactorial integrated systems operating in drinking behavior control in the central nervous system. In the present study acute third ventricle injections of Pb2+ (3, 30 and 300 pmol/rat) or Cd2+ (0.3, 3 and 30 pmol/ rat) blocked the dipsogenic response induced by third ventricle injections of isoproterenol (ISO; 160 nmol/rat) in a dose-dependent manner. Normohydrated animals receiving ISO + NaAc (sodium acetate) or saline (controls) displayed a high water intake after 120 min (ISO+saline = 5.78 +/- 0.54 ml/100 g; ISO+NaAc = 6.00 +/- 0.6 ml/100 g). After the same period, animals receiving ISO but pretreated with PbAc at the highest dose employed (300 pmol/rat) drank 0.78 +/- 0.23 ml/100 g while those receiving ISO and pretreated with the highest dose of CdCl2 (30 pmol/rat) presented a water intake of 0.7 +/- 0.30 ml/100 g. Third ventricle injections of CdCl2 (3 nmol/rat) or PbAc (3 nmol/rat) did not modify food intake in rats deprived of food for 24 h. Thus, general central nervous system depression explaining the antidipsogenic action of the metals can be safely excluded. It is concluded that both Pb2+ and Cd2+ inhibit water intake induced by central beta-adrenergic stimulation.

Adrenergic beta-Antagonists↗
PubMed1996

Modulatory role of nitric oxide on superoxide-dependent luminol chemiluminescence.

Reactive oxygen species are involved in luminol chemiexcitation induced in biological systems, but the contribution of nitrogen-derived oxidants in the process still remains unclear. Herein, we report that luminol chemiluminescence (LCL) induced by a superoxide (O2.-)- and hydrogen peroxide (H2O2)-generating system (2-25 mU/ml xanthine oxidase plus acetaldehyde and oxygen) was markedly inhibited by nitric oxide (.NO) added either as bolus (0-10 microM) or a continuous flow (0-10 microM/min). However, the inhibition of LCL was followed by an overshoot in light emission after most .NO was consumed or the infusion stopped and was due to reactions of remaining peroxynitrite, the product of the reaction between O2.- and .NO, with luminol. Nitric oxide also inhibited peroxynitrite- and glucose oxidase-induced LCL, but no overshoot was observed. On the other hand, a continuous flux of pure peroxynitrite, at 2 to 10 microM/min, induced LCL with quantum yields close to those obtained by identical micromolar fluxes of O2.-, while peroxynitrite formed from the decomposition of the sydnonimine SIN-1 yielded 76% of the chemiluminescence obtained with authentic peroxynitrite. Peroxynitrite-induced LCL was 80 and 55% inhibitable by SOD and catalase, respectively, showing that there were O2.- and H2O2-dependent routes of chemiexcitation. The hydroxyl radical scavengers dimethyl sulfoxide, mannitol, and ethanol and the metal chelator diethylenetriaminepentaacetic acid did not inhibit peroxynitrite-induced LCL while desferrioxamine was an efficient inhibitor of light emission by reaction with an activated state of peroxynitrous acid which is responsible of performing the initial one-electron oxidation of luminol. Our results are consistent with a dual role of .NO in O2.(-)-induced LCL: (I) formation of peroxynitrite which in turn promotes the light-emitting route and (II) reaction with luminol radical intermediates directing the system toward a dark pathway. These considerations are of critical importance when analyzing cell- and tissue-derived LCL in .NO-, O2.(-)-, and peroxynitrite-producing systems.

Acridines↗
PubMed1996

Cerebral venous thrombosis in young adults. Experience in a stroke unit, 1988-1994.

We report a series of nine patients younger than 45 years with angiographically-documented cerebral venous thrombosis, consecutively referred to our Stroke Unit from 1988 to 1994. Two of them were men and seven were women. Eight patients initially complained of headache, often associated with other symptoms of increased intracranial pressure. Seven patients had focal motor deficits and four suffered from epileptic seizures. None of the patients died. Only one patient remained severely disabled, whereas the others recovered self-sufficiency within two months. The use of oral contraceptives was closely associated with the occurrence of venous thrombosis in the women. Cerebral venous thrombosis is to be kept in mind in the differential diagnosis of stroke in the young.

Adolescent↗