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Biomedical subjects

M Navarro

Publications and source records attributed to M Navarro.

At least 199 records · Page 11Linked to original sources
PubMed1996

[Heart angiosarcoma and heart transplantation. Report of a case].

We present the case of a 29-year-old women with a cardiac primary angiosarcoma diagnosis. The initial symptom was a cardiac tamponade. The tests for screening metastasis proved negative. She was preoperatively treated with chemotherapy, followed by a heart transplant. There were no incidents related to surgery nor to the transplant except for a rejection in the second week biopsy. Four weeks after the transplant, the patient had a sudden dyspnea, the radiological tests confirmed the existence of a massive pleural overflow and lung and pleural metastasis. All types of therapeutical approaches were rejected except for pleurodesis. The patient died 60 days after the heart transplant.

Adult↗
PubMed1996

The morphometric study of the 19-day chicken embryo skeleton (gallus domesticus).

A series of 40 chicken embryos were processed after 19 d of incubation by dissection, diaphanisation, skeleton stained with alizarin red and examined by image analysis. Six bones (femur, tibiotarsus, tarsometatarsus, humerus, ulna and carpometacarpus) and 4 parameters (perimeter, area, the largest and the smallest Feret diameter) were evaluated. The smallest Feret diameter proved unusable. The coefficients of variation for the other 3 parameters were comparable for the 6 bones. All the bones were valuable for comparing morphometric values between a control population and a population treated with a xenobiotic in order to quantify the chemical's influence on ossification.

Animals↗
PubMed1996

Effects of B1 and B2 kinin receptor antagonists in diabetic mice.

Streptozotocin (STZ) has been extensively used to produce type I diabetes in animals. This experimental disease is characterized by a mild inflammatory reaction in the Langerhans islets. Because kinins have been proposed as prominent inflammatory mediators in the pathogenesis of several diseases, we decided to evaluate the role of kinins and their receptors in the evolution of insulitis. Male C57BL/Ks mdb mice were injected with STZ (40 mg/kg) for 5 consecutive days. The kinin B1 receptor antagonist [Leu8]des-Arg9-bradykinin or the B2 antagonist d-Arg[Hyp3,Thi5,D-Tic7, Oic8]bradykinin (HOE-140) was injected subcutaneously into STZ mice at 300 micrograms/kg body weight twice a day and 500 micrograms/kg per day, respectively. Treatment with antagonists was started 3 days after STZ and lasted for 10 days. Plasma glucose was determined by the glucose oxidase method, and urine samples collected on day 13 were assayed for proteins, nitrites, and kallikreins. Diabetic mice showed hyperglycemia and increased diuresis, marked proteinuria, and increased excretion of nitrites and kallikreins. The treatment with the B2 receptor antagonist did not show any effect on glycemia, but it significantly reduced water and protein excretion, compared with the STZ group. STZ mice treated with the B1 receptor antagonist showed normal glycemia and complete normalization of diuresis and protein, nitrite, and kallikrein excretion. The results obtained in the present investigation support the assumption that the kallikrein-kinin system intervenes in the maintenance of diabetic lesions, and they also indicate that B1 kinin receptors play a significant role in this experimental disease.

Analysis of Variance↗
PubMed1996

Angiogenesis in the gonadal capillary network of the chick embryo.

Seventy-one chick embryos of both sexes at the 35 Hamburger and Hamilton (H-H) developmental stage were processed for scanning electron microscopy of vascular corrosion casts and of critical point dried specimens, as well as transmission electron- and light microscopy, in order to study the angiogenic structures. The gonadal subepithelial capillary network was located at the level of the tunica albuginea under the covering epithelium. The casts showed a densely-meshed capillary network and numerous sprouting (nodular protrusions or capillary sprouts) and non-sprouting (enlarged vessels and angiogenic holes) angiogenic structures that were randomly distributed and mixed. Four types of angiogenic holes were encountered in the casts: primary (diameter < 2.5 microns), secondary (diameter > 2.5 microns), tertiary (variable diameter and circular narrowings on one side), and open angiogenic holes. We suggest that the different morphologies reflect evolution of these holes. Furthermore, the open angiogenic hole would probably either form nodular protrusions at its open ends, which tend to join with other nodular protrusions and neighboring capillaries and form new vessels; or there would be fusion with two or more neighboring open holes. Correlative critical point dried sections showed fenestrations in the capillary walls and transcapillary pillars that corresponded to the angiogenic holes found in the casts. Ultrathin sections of the vessels presented typical characteristics of growing endothelium: large nuclei with loosely textured chromatin, abundant cytoplasm rich in cell organelles and intraluminal endothelial processes.

Animals↗
PubMed1995

Determination of selenium in serum by hydride generation atomic absorption spectrometry for calculation of daily dietary intake.

Hydride generation atomic absorption spectrometry was used to determine the selenium concentrations in 130 samples of human serum from a control group of inhabitants in the southern part of the province of Granada (Spain). The mean selenium concentration in serum was 74.9 micrograms/l. This concentration did not vary significantly (P > 0.05) in relation to the sex of the subject, with concentrations of 80.6 micrograms/l in men and 70.7 micrograms/l in women. These mean values correspond to a mean daily dietary selenium intake of 50.4 micrograms per day in men and 44.6 micrograms per day in women. A considerable number of the individuals in the study area therefore have a daily selenium intake lower than the recommended dietary allowance of 70 micrograms per day for men and 55 micrograms per day for women. Likewise, the measured selenium concentrations in the basic health zones of the area were not statistically different (P > 0.05). The differences in selenium concentration between subjects in coastal zones and mountainous zones are therefore not significant.

Analysis of Variance↗
PubMed1995

The dopamine receptor agonist 7-OH-DPAT modulates the acquisition and expression of morphine-induced place preference.

The present study investigated the effects of systemic administration of the putative dopamine D3 receptor agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) on the acquisition and expression of morphine-induced place preference in male Wistar rats. Using a a 3-day schedule of conditioning it was found that 7-OH-DPAT in a broad dose range (0.01, 0.25 and 5.0 mg/kg) did not produce significant place preference. However, the administration of either 0.25 or 5.0 mg/kg of 7-OH-DPAT 15 min prior to the exposure to morphine (1 mg/kg) prevented the acquisition of a morphine place preference, whereas the 0.01 mg/kg dose of the dopamine receptor agonist was uneffective. In addition, when 7-OH-DPAT was acutely administered 15 min prior to the testing session of an already established morphine place preference, the 0.01 mg/kg dose prevented the expression of this conditioned response. This effect was not observed with either 0.25 and 5.0 mg/kg doses of this dopamine D3 receptor agonist. It was suggested that the different dose related effects of 7-OH-DPAT on the acquisition and expression of morphine place preference might be related to the intrinsic ability of this agonist for interacting with pre- and postsynaptic dopamine D3 receptors located in limbic projecting areas of the mesencephalic dopamine system, although involvement of dopamine D2 receptors cannot be excluded. The pattern of effects seen with 7-OH-DPAT suggests that it may be useful for treating opiate dependence and craving.

Analysis of Variance↗
PubMed1995

Behavioural consequences of maternal exposure to natural cannabinoids in rats.

Cannabis sativa preparations (hashish, marijuana) are the most widely used illicit drugs during pregnancy in Western countries. The possible long-term consequences for the child of in utero exposure to cannabis derivatives are still poorly understood. Animal models of perinatal cannabinoid exposure provide a useful tool for examining the developmental effects of cannabinoids. Behavioral consequences of maternal exposure to either cannabis preparations or to its main psychoactive component, delta 9-tetrahydrocannabinol (THC) in rat models are reviewed in this paper. Maternal exposure to cannabinoids resulted in alteration in the pattern of ontogeny of spontaneous locomotor and exploratory behavior in the offspring. Adult animals exposed during gestational and lactational periods exhibited persistent alterations in the behavioral response to novelty, social interactions, sexual orientation and sexual behavior. They also showed a lack of habituation and reactivity to different illumination conditions. Adult offspring of both sexes also displayed a characteristic increase in spontaneous and water-induced grooming behavior. Some of the effects were dependent on the sex of the animals being studied, and the dose of cannabinoid administered to the mother during gestational and lactational periods. Maternal exposure to low doses of THC sensitized the adult offspring of both sexes to the reinforcing effects of morphine, as measured in a conditioned place preference paradigm. The existence of sexual dimorphisms on the developmental effects of cannabinoids, the role of sex steroids, glucocorticoids, and pituitary hormones, the possible participation of cortical projecting monoaminergic systems, and the mediation of the recently described cannabinoid receptors are also analyzed. The information obtained in animal studies is compared to the few data available on the long-term behavioral and cognitive effects on in utero exposure to cannabis in humans.

Abnormalities, Drug-Induced↗
PubMed1995

Long-term behavioral effects of perinatal exposure to delta 9-tetrahydrocannabinol in rats: possible role of pituitary-adrenal axis.

This work evaluated motor behaviors in adult male and female rats exposed to delta 9-tetrahydrocannabinol (THC, 5 mg/kg) during gestation and lactation. The possibility that perinatal THC exposure induces sensitization to other drugs of abuse has also been addressed by evaluating morphine place preference conditioning (MPP) in the adult offspring. Maternal exposure to THC resulted in long-term effects on motor behaviors such as rearing, grooming and sniffing, in the adult offsprings of both sexes. Additionally, female offspring exposed to THC showed greater locomotor activity than controls, when measured using an actimeter. THC-exposed males exhibited an increased exploratory behavior in a plus-maze paradigm. When the adult animals were tested for MPP, THC-exposed offspring of both sexes exhibited an enhanced sensitivity to the rewarding effects of a moderate dose of morphine (350 micrograms/kg), an effect which was more marked in the males. These results showed that perinatal exposure to this psychoactive cannabinoid affected motor behaviors in the adult, suggesting a psychomotor activation very similar to that observed after gestational exposure to other drugs of abuse. A possible role of a THC-induced hypothalamus-pituitary-adrenal (HPA) axis activation was also evaluated in the present study. THC-exposed females exhibited higher levels of both corticotropin releasing factor (CRF-41) in the medial basal hypothalamus (MBH) and plasma corticosterone, whereas THC-exposed males showed the lower levels of both endocrine parameters. Since glucocorticoids are important modulators of both brain development, and adult brain function, these results indicate a possible role of HPA axis disturbances in the mediation of the behavioral effects described after perinatal THC exposure.

Adrenal Glands↗
PubMed1995

Location in the source chromosome of the 180-kb minichromosome of Leishmania major and characterization of the novel junction.

The 180-kb LD1 minichromosome of Leishmania major (M180) is a large inverted duplication which arises spontaneously from a megabasic chromosome. In this work this locus has been located in the source chromosome at a telomeric position. Both the novel junction created in the middle of the minichromosome, as well as its counterpart region in the source chromosome were cloned and sequenced. Two inverted repeats, which could give rise to two imperfect stem-loops, and an A + T-rich DNA sequence were the only particular features observed in this region. A putative model for the formation of the minichromosome is proposed.

Animals↗
PubMed1995

Changes in mandibular rotation after muscular resection. Experimental study in rats.

The purpose of this study was to evaluate the effect of bilateral muscular resection on the rotational pattern of the rat mandible. The specific aim of the study was to seek possible changes in "articular growth" in the posterior (ramus and condyle of the mandible), and in the anterior part of the face (upper viscerocranium, and maxillary and mandibular dentoalveolar processes). The masseter, temporal, and suprahyoid muscles were bilaterally resected in three experimental groups of 21-day-old female Wistar rats. Another group of rats served as control. The results were evaluated at 42 (prepubertal) and 60 days after birth (pubertal rats). The craniofacial growth pattern, ramus dimension, condylar growth direction, histologic evaluation of condylar cartilage, and dentoalveolar processes height changes were studied. Two mandibular rotational patterns were found: one inferior after masseter muscles resection (MR), and the other superior after temporal muscles resection (TR). A less intense superior rotational pattern, after suprahyoid muscles resection (SR), was found also. Morphologic changes were more intense in older rats. On the contrary, more intense condylar histologic changes were found in younger rats. Changes in "articular growth" primarily take place at maxillary and mandibular dentoalveolar processes. Condylar growth amount could be modified to a limited extent. More important were the changes in condylar growth direction. An upward rotational pattern of the upper viscerocranium was detected when the inferior mandibular rotation pattern was produced.

Age Factors↗
PubMed1995

Evidence from genotypic and phenotypic markers that an attenuated line outgrows a virulent one in a mixed population of Leishmania major promastigotes cultured in vitro.

Two cloned lines of Leishmania major promastigotes, one attenuated (CO1H) and one virulent (CO1R), differing in molecular karyotype and expression of the major surface glycoprotein (gp63), were mixed to produce two heterogeneous populations: MP-1 (100 CO1R promastigotes/CO1H promastigote); and MP-2 (10,000 CO1R promastigotes/CO1H promastigote). The mixed populations were cultured for 1 month in vitro in HO-MEM medium and sub-samples taken on days 4 and 30 were subjected to electrophoresis so that the molecular karyotypes and gp63-expression characteristics of the promastigote populations could be determined. In spite of the initial predominance of the virulent CO1R, the attenuated CO1H always outgrew it. The patterns of growth of pure cultures of CO1H or CO1R did not fully explain this observation. When grown alone, CO1H acidified the culture medium much more and much faster than CO1R, low pH values eventually inhibiting multiplication. Decreasing the medium's initial glucose concentration or increasing its initial pH prolonged the growth phase of CO1H, probably by slowing its acidification of the medium to inhibitory values. It is possible that, in mixed populations, the CO1R promastigotes help to buffer the medium, permitting faster and longer multiplication of the CO1H promastigotes than occurs when they are cultured alone. CO1H promastigotes may also inhibit CO1R multiplication; CO1H promastigotes in mid-logarithmic phase entered stationary phase within a day of being transferred into cell-free supernatants from 3-day-old CO1R cultures.

Animals↗
PubMed1995

alpha-Interferon therapy for congenital dyserythropoiesis type I.

We report the case of a 28-year-old female followed for congenital dyserythropoiesis type I which required repeated transfusions. Alpha-2a interferon treatment was started because of post-transfusion chronic viral hepatitis type C. Following this treatment, haemoglobin level increased and reached normal value during the 24 weeks of interferon treatment. When interferon therapy was stopped, haemoglobin level returned to previous values, requiring more transfusions. Resumption of interferon therapy resulted again in a complete normalization of haemoglobin level. Erythrokinetic studies demonstrated a striking reduction of the ineffective erythropoiesis, and electron microscopy study a reduction in nuclear structure abnormalities. To our knowledge, this is the first report of the efficacy of interferon in congenital dyserythropoiesis.

Adult↗
PubMed1995

Malformations of the vertebral bodies and the ribs associated to spinal dysraphism without spina bifida in a Pekingese dog.

A Pekingese dog with hemivertebrae, rib malformations and spinal cord dysraphism without spina bifida was presented. Two types of hemivertebrae were seen: bilateral and unilateral. Thoracic hemivertebrae were associated with fused ribs and rudimentary ribs. Spinal dysraphism consisted of polycavitary syringomyelia in the dorsal and lateral funiculi, hydromyelia and anomalies of the dorsal median septum and median fissure, associated to lumbar and sacral hemivertebrae. Cauda equina agenesia was also present. To conclude, the dog showed two malformations from different embryonic origins. Vertebral and rib malformations are of mesodermic origin and spinal dysraphism is of ectodermic origin. A possible common mechanism responsible for both anomalies is discussed.

Animals↗