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Biomedical subjects

M Muñoz

Publications and source records attributed to M Muñoz.

At least 145 records · Page 8Linked to original sources
PubMed1995

Anuran dorsal column nucleus: organization, immunohistochemical characterization, and fiber connections in Rana perezi and Xenopus laevis.

As part of a research program on the evolution of somatosensory systems in vertebrates, the dorsal column nucleus (DCN) was studied with (immuno)histochemical and tract-tracing techniques in anurans (the large green frog, Rana perezi, and the clawed toad, Xenopus laevis). The anuran DCN contains some nicotinamide adenine dinucleotide phosphate diaphorase-positive neurons, very little calbindin D-28k, and a distinct parvalbumin-positive cell population. The anuran DCN is innervated by primary and non-primary spinal afferents, by primary afferents from cranial nerves V, VII, IX, and X, by serotonin-immunoreactive fibers, and by peptidergic fibers. Non-primary DCN afferents from the spinal cord appear to arise throughout the spinal cord, but particularly from the ipsilateral dorsal gray. The present study focused on the efferent connections of the DCN, in particular the targets of the medial lemniscus. The medial lemniscus could be traced throughout the brainstem and into the diencephalon. Along its course, the medial lemniscus gives off collaterals to various parts of the reticular formation, to the octavolateral area, and to the granular layer of the cerebellum. At mesencephalic levels, the medial lemniscus innervates the lateral part of the torus semicircularis as well as various tegmental nuclei. A striking difference between the two species studied is that while in R. perezi medial lemniscal fibers do not reach the tectum mesencephali, in X. laevis, intermediate and deep tectal layers are innervated. Beyond the midbrain, both dorsal and ventral thalamic areas are innervated by the medial lemniscus. The present study shows that the anuran "lemniscal pathway" is basically similar to that of amniotes.

Animals↗
PubMed1995

An outbreak of diarrhoea associated with atypical rotaviruses in goat kids.

The presence of rotaviruses was investigated in the faeces of 31 goat kids in a dairy herd that experienced an outbreak of severe diarrhoea which caused dehydration, anorexia and prostration in seven (22.6 per cent) of them. All the affected animals were two to three days old. A group A-specific ELISA failed to detect rotaviruses in any of the samples but the characteristics electropherotype of group B rotaviruses was observed by electrophoresis in polyacrylamide gels in six of the animals. A highly significant statistical association between the shedding of rotavirus and the occurrence of diarrhoea was demonstrated. All the rotaviruses were detected in animals three to four days old. Cryptosporidium parvum, Clostridium perfringens and enterotoxigenic Escherichia coli were not detected in the seven diarrhoeic animals.

Animals↗
PubMed1995

Effect of interferon and 2',5'-oligoadenylates on rotavirus RNA synthesis.

Based on the antiviral effect of interferon on rotavirus replication the inhibitory effect of 2',5'-oligoadenylates on MRNA and double-stranded RNA synthesis was studied using an in vitro assay. The chemically synthesized oligonucleotides were used to determine several characteristics of the inhibitory effect, such as chain length, presence of phosphate residues at the 5'-end, and the 2',5'-phosphodiester bond itself. In vitro transcription was inhibited by oligos with 5 or more adenine residues at a final concentration of 100 microM or greater. This result makes rotavirus transcriptase different from other viruses in which the inhibitory effects are associated with dinucleotides and trinucleotides. The inhibitory effect was increased when the oligo contained a phosphate residue at the 5'-end; in this case, inhibition was also seen at lower oligo concentrations as well as at shorter oligo chain length. The study of the kinetics of inhibition showed that the inhibition by p(A2'p5')(3)3A was competitive with a Ki value of 256 microM. The effect of the oligonucleotides on the in vitro viral RNA replication showed that the 2',5'-oligoadenylates were not able to significantly inhibit the in vitro rotavirus RNA synthesis. The lack of inhibition in the in vitro assay was very peculiar since RNA transcription and replication involves the viral RNA polymerase, VP1.

Adenine Nucleotides↗
PubMed1995

Antiviral activity of phosphonoformate on rotavirus transcription and replication.

The antiviral effect of foscarnet (PFA) on the replication of rotavirus, a member of the Reoviridae, was studied. The pyrophosphate analogue is an effective inhibitor of several viral polymerases acting on the enzyme pyrophosphate binding site. Replication of rotavirus in MA104 cells using different u.o.i. was inhibited by PFA in a concentration dependent manner, due to the inhibition of both plus- and minus-strand RNA synthesis. The addition of PFA to infected cells was specific for the inhibition of viral replication since uninfected cell incubated at the same PFA concentrations did not exhibit any cytotoxic effect. The 50% inhibitory effect of PFA on in vitro mRNA synthesis was obtained at a concentration of 150 microM. Over 80% of the in vitro minus-strand RNA synthesis was inhibited at a concentration of 320 microM, when PFA was assayed using replicase-enriched cell infected fraction. The results suggest that the effect may be due to an interaction of PFA with the viral polymerase, since this protein catalyses both plus- and minus-strand RNA synthesis. The results of experiments using the temperature-sensitive viral polymerase mutant show that the mutant is less sensitive to PFA, suggesting that this polypeptide is the target for PFA.

Animals↗
PubMed1995

The trochlear nucleus of the frog Rana ridibunda: localization, morphology and ultrastructure of identified motoneurons.

The organization of the trochlear nucleus (N IV) was investigated in the frog Rana ridibunda. Retrograde tracing with horseradish peroxidase and biotinylated dextran amines resulted in labeling on the contralateral N IV of motoneurons with diverse morphologies and in direct caudal continuation with the oculomotor nucleus. Their dendritic arborizations extend profusely in the ipsilateral tegmentum and reach the oculomotor nucleus, the fasciculus longitudinalis medialis and also small processes branch towards the ventricle. Occasionally, one to three cells are labeled in the ipsilateral N IV, whereas mesencephalic trigeminal cells that would send their peripheral branch in the IVth nerve are never observed. The course of the labeled trochlear axons varies depending on the localization within the N IV of their cells of origin and different points of decussation are present above the midbrain ventricle. The ultrastructural analysis of identified trochlear motoneurons shows numerous axo-somatic synaptic contacts and six types of terminals with variable morphologies have been observed. Among them, a peculiar type of axon terminal forms mixed junctions with synaptic specializations and gap junctions together in the membrane interfaces that could represent the simultaneous presence of a chemical as well as an electrical component. The present data give more insights into the organization of the N IV and demonstrate that, although the organization of the trochlear nucleus is highly conservative in gnathostome vertebrates, it shows specific features for each species studied, as demonstrated for amphibians.

Animals↗
PubMed1995

Prevalence of neutralizing antibodies to 9 rotavirus strains representing 7 G-serotypes in sheep sera.

Neutralizing antibodies to 9 rotavirus strains representing serotypes G1, G3, G5, G6, G8, G9, and G10 were investigated in 212 ovine serum samples from 3 age groups, 1-week-old lambs, 2- to 3-months-old lambs and adult sheep. All sera from 1-week-old lambs had neutralizing antibodies to all 9 rotavirus strains. Both neutralizing antibody titers and prevalences to all 9 strains markedly decreased in the 2- to 3-months-old lamb group and increased again in the adult sheep group. Also, adult sheep sera neutralized a larger number of rotavirus strains than 2- to 3-months-old lamb sera. The highest neutralizing antibody titers and prevalences were found to strains B223 and K923, representing serotype G10, to strain RRV, representing serotype G3, and to strain NCDV, representing serotype G6, indicating that these could be the predominant 3 rotavirus serotypes in Spanish sheep. The rotavirus serotypes infecting sheep observed by us differ from those described for cattle, where G6 is the most prevalent serotype followed by G10, and G3 has been seldom found. Very low prevalences were observed for strains WA and OSU representing serotypes G1 and G5 respectively, suggesting that they probably do not infect sheep and neutralizing antibodies found are derived from heterotypic responses to other serotypes. Intermediate prevalences and titers were found to strains UK (serotype G6), 69M (serotype G8) and WI61 (serotype G9). Neutralizing antibodies distinguished between different strains sharing their VP7 specificity: B223 and K923, a bovine and an ovine serotype G10 strains, and NCDV and UK, two serotype G6 bovine rotavirus strains with different VP4 antigen.

Aging↗
PubMed1995

Comparative antimicrobial study of the resinous exudates of some Chilean Haplopappus (Asteraceae).

The antimicrobiol properties and preliminary chemical information of the resinous exudates from twigs and leaves of nine Haplopappus species from Chile: H. diplopappus; H. anthylloides; H. schumannii; H. cuneifolius; H. velutinus; H. uncinatus; H. multifolius, H. illinitus and H. foliosus are presented. The results show that those species of genus Haplopappus share similar antimicrobial activities although they differ dramatically in the chemical composition.

Anti-Bacterial Agents↗
PubMed1995

Ontogeny of vasotocinergic and mesotocinergic systems in the brain of the South African clawed frog Xenopus laevis.

For a better understanding of the development of neurotransmitter systems and of their putative functional significance during ontogenesis, the development of the vasotocin (AVT) and mesotocin (MST) systems in the brain of Xenopus laevis was studied by means of immunohistochemical techniques. Weakly immunoreactive fibers were already present at late embryonic stage 38 in the caudoventral part of the telencephalon and in the ventral part of the diencephalon. The earliest immunodetectable AVT and MST immunoreactive cell bodies were found in the developing preoptic area at late embryonic stage 43. At the end of the embryonic period (stage 45), AVT immunoreactive fibers have reached the future medial amygdala, the midbrain tegmentum, the median eminence and the neural lobe of the pituitary. When compared with AVT immunoreactive fibers, the development of MST fibers shows some temporal delay. During the premetamorphosis (stages 45-52), AVT immunoreactive cell bodies appear in the medial part of the suprachiasmatic nucleus, the dorsal infundibular region, and the midbrain tegmentum, whereas fibers can now be traced to the nucleus accumbens, the septum and the medial amygdala in the forebrain, to the midbrain tegmentum, the reticular formation, the raphe nuclei, and the solitary tract nucleus in the brainstem, and to the spinal cord. Further maturation of the AVT system during prometamorphosis (stages 53-58) includes the appearance of immunoreactive cell bodies in the lateral part of the suprachiasmatic nucleus, the ventral preoptic area, and the dorsal infundibular region. By the end of the metamorphosis (stage 65), the maturation of the AVT/MST systems reaches an almost adult-like pattern. It should be noted that in amphibians, in contrast to mammals, the early appearance of the AVT/MST systems, including their extensive extrahypothalamic component, suggests that the two neuropeptidergic systems may play a significant role during development.

Animals↗
PubMed1995

Open-angle glaucoma after pars plicata lensectomy and vitrectomy for congenital cataracts.

PURPOSE/METHODS: We examined an infant with familial cataracts in whom bilateral open-angle glaucoma developed shortly after pars plicata lensectomy with anterior vitrectomy. RESULTS/CONCLUSIONS: Some eyes with congenital nuclear cataracts have a predisposition to develop glaucoma after removal of the cataract, which is irrespective of the method chosen to remove the cataract. Careful monitoring of the intraocular pressure is indicated.

Cataract↗
PubMed1995

Appearance of resistance to beta-lactam antibiotics during therapy for Streptococcus pneumoniae meningitis.

A young boy had meningitis caused by Streptococcus pneumoniae that was relatively resistant to penicillin and susceptible to cefotaxime. After 10 days of therapy with penicillin and cefotaxime, fever recurred and a second lumbar puncture revealed a pneumococcus that was resistant to all beta-lactam antibiotics. We now add vancomycin to empiric third-generation cephalosporin therapy for meningitis in children when gram-positive cocci are seen on the cerebrospinal fluid smear.

Cefuroxime↗
PubMed1995

Microphthalmos, facial capillary hemangioma and Dandy-Walker malformation.

We present a 6-month-old girl with the unusual combination of microphthalmos, facial capillary hemangioma and Dandy-Walker malformation. This is the fourth case with such an association reported in the literature. On the basis of the experience with our patient and with those previously reported, we stress the importance of performing brain-imaging studies on all infants with large facial hemangiomas, or if unusual ophthalmic findings are present.

Abnormalities, Multiple↗
PubMed1995

Insulin stimulates cationic amino acid transport activity in the isolated perfused rat pancreas.

The effects of exogenous insulin, glucagon and streptozotocin-diabetes on influx (15 s) of L-lysine via a cationic amino acid transporter resembling system y+ were investigated in the isolated perfused rat pancreas. In non-diabetic pancreata, transport of L-lysine was saturable with an apparent Km of 2.11 +/- 0.29 mM and Vmax of 2.21 +/- 0.20 mumol min-1 g-1 (n = 6). Bovine insulin (100 mu u ml-1) increased the maximal transport rate (Vmax = 3.49 +/- 0.30 mumol min-1 g-1, n = 4, P < 0.05) for L-lysine 1.6-fold without altering the Km. L-Lysine transport was not elevated significantly in diabetic pancreata, although insulin (100 mu u ml-1) enhanced transport to values measured in non-diabetic preparations. Human glucagon (1.5 x 10(-9) M) had no stimulatory effect on L-lysine transport. These findings provide the first evidence that exogenous insulin stimulates cationic amino acid transport activity in the exocrine pancreatic epithelium. Activation of the cationic pancreatic amino acid transporter may provide a mechanism to enhance the supply of L-arginine and thus sustain nitric oxide-mediated pancreatic secretion in response to islet hormones and secretagogues.

Amino Acids↗
PubMed1995

Modifications in the distribution of met-enkephalin in the limbic system of the cat brain after electroacupuncture. An immunocytochemical study.

The distribution of met-enkephalin in the limbic system of the cat brain and its modification after low frequency electroacupuncture (EA) stimulation have been studied experimentally using the indirect immunocytochemistry technique. A marked increase of post-stimulation met-enkephalin immunoreactivity was observed in the tractus habenulo-penduncularis, tractus mamilo-thalamicus, and medial forebrain bundle, and a decrease at the level of the nucleus interpeduncularis, medialis dorsalis, stria terminals, septalis lateralis, septalis medialis, accumbens septi, supraopticus, and amygdaloideus centralis. The experimental results link the changes in immunoreactivity (and therefore the structures in which they take place) with the action of low frequency EA, and permit the conclusion that the met-enkephalinergic portion of the limbic system studied is directly related morpho-functionally with analgesia and the anatomic pathways of pain.

Animals↗
PubMed1994

Acquired double elevator palsy in a child with a pineocytoma.

PURPOSE/METHODS: We examined an 8-year-old girl who had an acquired double elevator palsy and a histopathologically confirmed benign pineocytoma. RESULTS/CONCLUSIONS: Mass lesions in the region of the pineal gland can produce monocular blepharoptosis and supranuclear upgaze paresis with the resultant clinical picture of double elevator palsy.

Blepharoptosis↗
PubMed1994

Inferior rectus muscle overaction after cataract extraction.

PURPOSE/METHODS: I reviewed the motility of two patients who had binocular vertical diplopia after cataract operations with peribulbar anesthesia. RESULTS/CONCLUSIONS: The binocular diplopia in these patients was a result of inferior rectus muscle overaction in the absence of restriction or weakness of the antagonist muscle. The mechanism could be related to myotoxicity of the anesthetic agents.

Aged↗
PubMed1994

Leiomyosarcoma of the soft tissues in a patient with nevoid basal-cell carcinoma syndrome.

A 57-year-old man was admitted with complaints of progressive anorexia, weight loss and right flank pain. He had been treated for basal-cell carcinoma of the skin 19 years before. On physical examination, eight moles in the face, back and left thigh were found along with palmar pits. In addition, a painful induration in his right thigh was evident. Biopsy proved that six moles were basal-cell carcinomas and the thigh mass a high-grade leiomyosarcoma. Computed tomographs revealed multiple metastases in the lungs and the liver. The patient was treated with epirubicin, with partial response, and subsequently with ifosfamide. He died 17 months after diagnosis. Whereas the world literature records several cases of soft tissue tumors in patients with nevoid basal-cell carcinoma syndrome, this is the first report of a simultaneous occurrence of leiomyosarcoma and nevoid basal-cell carcinoma syndrome.

Basal Cell Nevus Syndrome↗