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Biomedical subjects

J Leal

Publications and source records attributed to J Leal.

At least 37 records · Page 2Linked to original sources
PubMed1994

Antisocial personality disorder as a prognostic factor for pharmacotherapy of cocaine dependence.

Pharmacotherapy response was compared in 94 cocaine-abusing methadone patients with (n = 75) and without (n = 19) antisocial personality disorder (ASP), in a 12-week, randomized, double-blind trial using desipramine 150 mg daily (n = 30), amantadine 300 mg daily (n = 33), and placebo (n = 31). Retention was lower for the ASP group (ASP 9.6 weeks vs. non-ASP 11.2 weeks). During the first 2 weeks, there was no significant difference in the percentage of cocaine-free urines between the ASP vs. non-ASP patients (9% vs. 18%), but during the last 2 weeks, the non-ASP patients showed a significantly greater percentage of cocaine-free urines (30% vs. 7%). Placebo-treated patients in both groups demonstrated no significant difference in their urine toxicologies comparing the first to the last two weeks of treatment. However, the percentage of cocaine-free urines increased from 15% to 32% in medicated non-ASP patients, but showed no change in medicated ASP patients. Thus, antisocial personality disorder was a poor prognostic factor for treatment retention and continued cocaine abuse, and medication did not improve treatment outcome for the ASP patients, but did for the non-ASP patients.

Adult↗
PubMed1990

Development of chicken embryos in a pulsed magnetic field.

Six independent experiments of common design were performed in laboratories in Canada, Spain, Sweden, and the United States of America. Fertilized eggs of domestic chickens were incubated as controls or in a pulsed magnetic field (PMF); embryos were then examined for developmental anomalies. Identical equipment in each laboratory consisted of two incubators, each containing a Helmholtz coil and electronic devices to develop, control, and monitor the pulsed field and to monitor temperature, relative humidity, and vibrations. A unipolar, pulsed, magnetic field (500-microseconds pulse duration, 100 pulses per s, 1-microT peak density, and 2-microseconds rise and fall time) was applied to experimental eggs during 48 h of incubation. In each laboratory, ten eggs were simultaneously sham exposed in a control incubator (pulse generator not activated) while the PMF was applied to ten eggs in the other incubator. The procedure was repeated ten times in each laboratory, and incubators were alternately used as a control device or as an active source of the PMF. After a 48-h exposure, the eggs were evaluated for fertility. All embryos were then assayed in the blind for development, morphology, and stage of maturity. In five of six laboratories, more exposed embryos exhibited structural anomalies than did controls, although putatively significant differences were observed in only two laboratories (two-tailed Ps of .03 and less than .001), and the significance of the difference in a third laboratory was only marginal (two-tailed P = .08). When the data from all six laboratories are pooled, the difference in incidence of abnormalities in PMF-exposed embryos (approximately 25 percent) and that of controls (approximately 19 percent), although small, is highly significant, as is the interaction between incidence of abnormalities and laboratory site (both Ps less than .001). The factor or factors responsible for the marked variability of inter-laboratory differences are unknown.

Animals↗
PubMed1990

Cardiopulmonary resuscitation with simultaneous chest and abdominal compression: comparative study in humans.

To assess the efficacy of the simultaneous application of chest and abdominal compression (SCAC) in cardiopulmonary resuscitation (CPR), we performed a prospective study on 18 patients shortly after cardiac arrest. Three different CPR procedures were carried out consecutively: (1) Standard CPR; (2) CPR interposed with abdominal compression (IAC-CPR); and (3) SCAC-CPR. Standard CPR was repeated at the end of each sequence. Thoracic aortic and right atrial pressures were recorded during maneuvers and no vasoactive drugs were administered. Systolic aortic pressures were 39.02 +/- 21 mmHg, 63.6 +/- 21 mmHg and 94.04 +/- 21 mmHg during standard CPR, IAC-CPR and SCAC-CPR, respectively (P less than 0.001). There was no evidence of intra-abdominal injury in the eight autopsies performed. We have reached the conclusion that the use of SCAC-CPR on humans does produce greater intravascular pressure and we recommend this technique as a possible alternative to standard CPR.

Aged↗
PubMed1990

Percutaneous absorption of 17 beta-estradiol in ovariectomized rhesus monkeys: skin and serum pharmacokinetics.

The skin and serum kinetics of percutaneous estradiol (E2) gel (Oestrogel; Besins-Iscovesco Laboratories, Paris, France) absorption in 11 ovariectomized rhesus monkeys (3 pretreated with diethylstilbestrol [DES]) was studied. The gel (1.5 mg E2) mixed with 7.5 x 10(5) cpm tritiated E2 (3H-E2) was applied to abdominal skin. Serial skin biopsies were taken from the application area and at 1 and 3 cm beyond, as well as from perineum and dorsal skin; and radioactivity measured to estimate tissue levels of E2 derived from percutaneous delivery. Simultaneous femoral serum samples were taken for RIA of E2. Skin 3H-E2 reached a peak at approximately 60 minutes, which was sustained for about 10 hours. Lateral diffusion of the radiolabeled E2 was limited to about 1 cm. Serum E2 levels reached a peak at 60 minutes and remained elevated for 20 hours after a single application. A strong correlation existed between skin and serum E2 levels: r = 0.828. DES did not modify the E2 skin absorption kinetics, but in 2 of 3 monkeys DES reduced the E2 serum levels, suggesting an effect after skin absorption. We conclude that percutaneously delivered E2 manifests a sustained entry into serum. The steady state of continuous release of E2 into circulation derives from a postabsorption skin reservoir of estrogen product.

Administration, Cutaneous↗
PubMed1989

Systemic and regional hemodynamics in patients with liver cirrhosis and ascites with and without functional renal failure.

Systemic, femoral, and renal hemodynamics were evaluated in 7 control subjects and 20 cirrhotic patients with ascites, 14 of them without (group A) and 6 with (group B) functional renal failure. Hyperdynamic systemic circulation, increased plasma volume, and hyperreninism were present in groups A and B. These changes were more severe in group B, which showed, as compared with group A, lower total vascular resistances and mean arterial pressure together with increased cardiac index and plasma renin activity. Significant differences in regional hemodynamics were also observed between groups. In group A, femoral and renal fractions of cardiac output were respectively increased and reduced as compared with controls. By contrast, in group B, both fractions of cardiac output were reduced when compared either with controls or with group A. In the entire patient group there was a close direct correlation between femoral and renal fractions of cardiac output (r = 0.88; p less than 0.001) and both of them correlated independently with total vascular resistances (r = 0.79; p less than 0.001 in both cases). These results indicate that, in nonazotemic cirrhotics with ascites, vasodilatation in extrasplanchnic areas contributes to the genesis of the hyperdynamic circulation. The presence in group B of a reduced flow to extrasplanchnic territories, in association with an increase of the hyperdynamic circulatory status, suggests that exacerbation of splanchnic vasodilatation is involved in the development of the hepatorenal syndrome. Finally, in cirrhosis, the changes that occur in systemic hemodynamics appear to influence renal function and renal blood flow.

Aldosterone↗
PubMed1989

[Hypothalamic inhibiting factor of luteinizing hormone secretion: relation to the fragment 1-5 of the LH releasing hormone].

In this paper we review the mechanisms underlying the control of gonadotrophin (Gn) release and present evidences of the existence of a luteinizing hormone release-inhibitory factor. We have extracted and partially characterized this factor from rat hypothalamus and bovine median eminence. Our data indicate that the factor is a peptide that has a common antigenic determinant with GnRH, but is of smaller molecular weight than GnRH (750 daltons approximately). These facts strongly suggest that it may be a fragment of the GnRH molecule. The synthetic fragment GnRH (1-5) has similar biologic effects and molecular weight to those of the inhibitory factor obtained from the median eminence and hypothalamus. GnRH (1-5) has been shown to be produced in vitro by cleavage of GnRH by an hypothalamic endopeptidase. Based on this evidences, we suggest that the inhibitory peptide found by us is formed in vivo by degradation of GnRH. Moreover, we suggest that this factor may play a role on the regulation of LH release induced by GnRH.

Animals↗
PubMed1988

Gonadotropin-releasing hormone (GnRH) inhibits ovulation induced with luteinizing hormone (LH) in proestrous hypophysectomized rats.

In this paper we present evidence that a single low dose of the natural synthetic gonadotropin-releasing hormone (GnRH), inhibits ovulation induced by LH in proestrous-hypophysectomized rats. Rats hypophysectomized by the parapharyngeal route in the morning of proestrus received an intravenous injection of 100 or 300 ng GnRH at 1400 h immediately followed by 1.0 microgram LH per 100 g bw. In control groups, either one or both hormones were replaced with 0.9% NaCl. Ovulation was assessed the following morning by counting the ova present in oviductal flushings. All the rats treated with LH alone ovulated, and the addition of GnRH reduced significantly the number of ovulating rats and the number of ova per ovulating rat. In other groups of rats hypophysectomized in the morning of proestrus and treated in the same way, ovarian or adrenal secretory rates of estradiol and/or progesterone were measured after cannulation of the corresponding vein, in the afternoon of proestrus. In these animals, GnRH failed to inhibit either the ovarian progesterone surge observed 2 h after LH administration, or the adrenal progesterone secretion. All hypophysectomized rats showed lower ovarian secretory rate of estradiol than intact rats; this rate was not affected by treatment with LH or LH plus GnRH. The systemic estradiol levels in plasma of hypophysectomized rats were distributed within a range of 20 pg/ml to 50 pg/ml. The number of rats whose levels were above 21 pg/ml on estrus day was significantly higher in rats receiving 300 ng GnRH as compared to those receiving 100 ng GnRH, reaching values that surpassed the concentration found in intact, untreated animals at the same time of estrus. This effect did not depend on LH administration.

Adrenal Glands↗
PubMed1988

Mesenteric shunting during thoracoabdominal aortic clamping to prevent disseminated intravascular coagulation in dogs.

The current study was undertaken to determine if cold crystalloid perfusion of the mesenteric circulation or continuous arterial shunting into the superior mesenteric artery would prevent the subsequent development of disseminated intravascular coagulation in a dog model. Twenty-two dogs were divided into four groups: those with distal aortic occlusion; those with isolated washout of the mesenteric circulation via the superior mesenteric artery with cold crystalloid; those with continuous isolated arterial perfusion of the superior mesenteric artery via an open proximal aorta; and those with shunting of blood into the superior mesenteric artery from the proximal aorta with an Inahara-Pruitt shunt. Coagulation parameters were measured for 24 hours and compared to the results with 32 dogs in the following groups: sham operation; supraceliac aortic occlusion for 30 minutes, 60 minutes, 90 minutes; superior mesenteric occlusion for 90 minutes; and celiac axis occlusion for 90 minutes. Shunting or direct arterial perfusion of the superior mesenteric artery prevented disseminated intravascular coagulation from occurring. Infrarenal aortic occlusion resulted in no change in any of the coagulation factors, whereas crystalloid perfusion of the superior mesenteric artery resulted in death in all animals. These results indicate that the disseminated intravascular coagulation that occurs with supraceliac aortic occlusion or superior mesenteric occlusion of greater then one hour can be prevented by continuous arterial perfusion of the superior mesenteric artery during proximal aortic clamping.

Animals↗
PubMed1987

Superior mesenteric artery balloon occlusion. A nonoperative model of small bowel ischemia in dogs.

The purpose of this study was to develop a nonoperative animal model of small bowel ischemia that could be used for subsequent studies of intestinal ischemia. Ten mongrel dogs underwent balloon occlusion of their superior mesenteric artery after percutaneous insertion of a balloon tipped catheter through the femoral artery. Small bowel biopsies taken at various time intervals demonstrated mucosal congestion, hemorrhage, and sloughing consistent with classic small bowel ischemia. These changes consistently began 3 hours after occlusion with transmural necrosis and perforation occurring by 18 hours after occlusion. Fluoroscopy demonstrated little or no flow in the mesenteric circulation during balloon occlusion. This model provides a standard nonoperative approach for the induction of intestinal ischemia in dogs and could be a valuable tool in the study of intestinal ischemia.

Animals↗
PubMed1985

Retrograde nephrostomy and percutaneous calculus removal in 30 patients.

We used a new technique, retrograde nephrostomy, to provide intrarenal access for percutaneous calculus removal in 30 consecutive patients. Under fluoroscopic control, we maneuvered cystoscopically a 5F and 9F coaxial catheter pair over a guide wire into the calix selected for nephrostomy. Then, a sheathed 20 to 21 gauge needle was passed through the 9F catheter into the flank to create the nephrostomy. Eight patients were given general and 22 intravenous sedation and local anesthesia for nephrostomy placement and calculus removal. Retrograde nephrostomy and subsequent calculus removal were completed successfully in 90 and 83 per cent of the 30 patients, respectively. There were 6 complications and 3 failures among the first few patients due to inferior equipment and inexperience with the technique. Over-all, we found that retrograde nephrostomy provided reliable, precise intrarenal access and we believe that it could become an alternative technique to aid in percutaneous calculus removal procedures.

Adult↗
PubMed1983

Pulse shape of magnetic fields influences chick embryogenesis.

A total of 295 chick embryos was exposed during the first 48 hours of development to pulsed electromagnetic fields of 100 Hz and 0.4 to 104 microTeslas (micro T), and findings were compared with those in 364 control embryos. General morphology was analysed and supplemented by light microscopy studies. Exposure to electromagnetic fields with a pulse rise time of 100 microseconds produced teratogenic changes when intensities of 1.0 and 13.9 micro T were used but not with lower or higher intensities, demonstrating a 'window' effect and ruling out the possible influence of a rise in internal embryonic temperature. Exposure to an electromagnetic field of 1.0 micro T specifically altered organogenesis of the truncal nervous system and drastically reduced the alcian blue-stained components, whereas with an intensity of 13.9 micro T, there were abnormalities in the circulatory system and foregut, altering cell-to-cell contacts in the walls of developing vessels. When embryos were exposed to intensities of 0.4 and 1.0 micro T with 2.0 and 42 microseconds pulse rise times, teratogenic effects were greater and alterations involved all developing systems. The most powerful effects were obtained with 1.0 micro T and 42 microseconds rise time. The findings confirm the sensitivity of chick embryos to electromagnetic fields of extremely low frequency and intensity and indicate that pulse shape may be a decisive parameter determining strong, slight, or no modification of embryonic development. Mechanisms of action of electromagnetic fields are still unclear, but induced alterations in extracellular glycosaminoglycans could be a causal factor in the observed malformations.

Animals↗
PubMed1982

Embryological changes induced by weak, extremely low frequency electromagnetic fields.

Fertilized chicken eggs were incubated for 48 hours while exposed to extremely low frequency magnetic fields (ELMF) of 10 Hz, 100 Hz and 1000 Hz with intensities of 0.12, 1.2 and 12 micro T. Gross morphological and histological analysis of the exposed embryos revealed the following effects: (1) ELMF of 100 Hz/1.2 micro T had the most consistent and powerful inhibitory effect on embryogenesis. Development of embryos was reduced to the formation of the three primitive layers. Brain vesicles, auditory pit, neural tube, foregut, heart, vessels, and somites were not developed. Glycosaminoglycans were almost absent. (2) The above results demonstrate a window effect because embryos exposed to 100 Hz/1.2 micro T were less developed than embryos exposed at lower and higher intensities and frequencies. (3) Developing organs reacted with different sensitivity to ELMF of specific frequencies and intensities. Somites were not disturbed by exposure to 10 Hz with any of the intensities used. Formation of blood vessels was completely blocked by ELMF of 1000 Hz/12 micro T while traces of other organs were present. (4) The drastic embryological disturbances described were obtained with much lower intensities (1 micro T = 0.01 Gauss) than those used in studies by other investigators. (5) Embryological alterations induced by ELMF may depend on disturbances in the presence and structure of glycosaminoglycans which are essential elements in cellular activities, including cell migration. (6) The use of ELMF of low intensity may be a powerful method to investigate embryogenetic mechanisms and may also be a useful technique for investigation of other biological systems.

Animals↗
PubMed1978

Idiopathic priapism in the newborn.

Priapism in children usually results directly or indirectly from an underlying cause. Secondary priapism is extremely rare in neonates and idiopathic priapism has not been described previously.

Humans↗
PubMed1977

Tricuspid atresia and pregnancy.

Tricuspid atresia is one of the rarest heart defects, and it is rarely associated with prolonged survival. This paper describes the third known case of pregnancy associated with tricuspid atresia. This is the first detailed report of the clinical course of a patient with this disorder. Complications included heart failure, multiple pulmonary emboli, cerebral embolization, and premature labor. Recommendations are made regarding patient care.

Adult↗