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Biomedical subjects

M Muñoz

Publications and source records attributed to M Muñoz.

At least 127 records · Page 7Linked to original sources
PubMed1997

Plant regeneration of indica rice (Oryza sativa) cultivars from mature embryo-derived calli.

Plant regeneration from seven-week-old callus cultures derived from mature embryos of several indica rice cultivars was achieved with frequencies of morphogenic calli from 10 to 47%. Three media were tested both for callogenesis and plant regeneration. For 3 of the 7 genotypes examined, the best combination of media for plant regeneration was Murashige & Skoog basal medium: MSC (callogenesis) and MSR (regeneration). The rates of callogenesis were not related to the capacity for plant regeneration. Two genotypes CR-1113 and CR-5272 produced the highest number of regenerated green plants. The results of this study suggest that genetic differences could be directly linked to the ability to regenerate in these plant cultivars.

Culture Techniques↗
PubMed1996

Nitric oxide synthase in the brain of a urodele amphibian (Pleurodeles waltl) and its relation to catecholaminergic neuronal structures.

The neuronal structures with NADPH-diaphorase activity and nitric oxide synthase (NOS) immunoreactivity have been studied in the brain of the urodele amphibian Pleurodeles waltl by means of histochemical and immunocytochemical techniques. Both approaches resulted in the selective labeling of the same neurons and fiber tracts in the brain, except for the primary olfactory fibers that did not stain for NOS but were positive for NADPH-diaphorase. NOS-containing neurons were found in the olfactory bulbs, pallial regions, septum, caudal striatum, amygdala and preoptic area. Only a few diencephalic cells were labeled in the posterior tubercle and ventral hypothalamus. In the brainstem, abundant cells were labeled in the tectum, mesencephalic tegmentum and isthmic region. The most conspicuous cell population was found in the isthmic-pretrigeminal region. Particularly well stained cells were distributed throughout the rhombencephalon in areas related to the descending trigeminal tract, solitary tract, raphe nucleus and the mid-caudal reticular formation. In the cervical spinal cord, NOS-containing cells were present in the dorsal, intermediate and ventral grey fields. Cells in the preoptic, postotic and dorsal root ganglia were also labeled. Double labeling techniques revealed an extensive codistribution of neurons with NOS and catecholamines in the urodele brain but actual colocalization in the same cells was never observed. The organization of the central systems in urodeles with NOS appears to share many features not only with other anamniotes but also with amniotes.

Animals↗
PubMed1996

Topographical distribution of NADPH-diaphorase activity in the central nervous system of the frog, Rana perezi.

The distribution of NADPH-diaphorase (ND) activity was histochemically investigated in the brain of the frog Rana perezi. This technique provides a highly selective labeling of neurons and tracts. In the telencephalon, labeled cells are present in the olfactory bulb, pallial regions, septal area, nucleus of the diagonal band, striatum, and amygdala. Positive neurons surround the preoptic and infundibular recesses of the third ventricle. The magnocellular and suprachiasmatic hypothalamic nuclei contain stained cells. Numerous neurons are present in the anterior, lateral anterior, central, and lateral posteroventral thalamic nuclei. Positive terminal fields are organized in the same thalamic areas but most conspicuously in the visual recipient plexus of Bellonci, corpus geniculatum of the thalamus, and the superficial ventral thalamic nucleus. Labeled fibers and cell groups are observed in the pretectal area, the mesencephalic optic tectum, and the torus semicircularis. The nuclei of the mesencephalic tegmentum contain abundant labeled cells and a conspicuous cell population is localized medial and caudal to the isthmic nucleus. Numerous cells in the rhombencephalon are distributed in the octaval area, raphe nucleus, reticular nuclei, sensory trigeminal nuclei, nucleus of the solitary tract, and, at the obex levels, the dorsal column nucleus. Positive fibers are abundant in the superior olivary nucleus, the descending trigeminal, and the solitary tracts. In the spinal cord, a large population of intensely labeled neurons is present in all fields of the gray matter throughout its rostrocaudal extent. Several sensory pathways were heavily stained including part of the olfactory, visual, auditory, and somatosensory pathways. The distribution of ND-positive cells did not correspond to any single known neurotransmitter or neuroactive molecule system. In particular, abundant codistribution of ND and catecholamines is found in the anuran brain. Double labeling techniques have revealed restricted colocalization in the same neurons and only in the posterior tubercle and locus coeruleus. If ND is in amphibians a selective marker for neurons containing nitric oxide synthase, as generally proposed, with this method the neurons that may synthesize nitric oxide would be identified. This study provides evidence that nitric oxide may be involved in novel tasks, primarily related to forebrain functions, that are already present in amphibians.

Animals↗
PubMed1996

A region of the integrin VLA alpha 4 subunit involved in homotypic cell aggregation and in fibronectin but not vascular cell adhesion molecule-1 binding.

The VLA-4 (alpha 4 beta 1) integrin is involved in the adhesion of cells to fibronectin and vascular cell adhesion molecule-1 (VCAM-1). In order to study alpha 4 structure-function relationships, we have expressed mutated alpha 4 subunit by transfection into VLA-4-negative K562 cells. Substitutions at alpha 4 residues Arg89-Asp90, which show the highest surface probability indexes inside the N-terminal alpha 4/80 fragment, resulted in a reduction in the reactivity of all anti-alpha 4 epitope A monoclonal antibodies (mAbs) tested, compared with the reactivity with anti-alpha 4 epitopes B1, B2, and C mAb, both by transfectant flow cytometry, and by immunoprecipitation and SDS-polyacrylamide gel electrophoresis analysis of transfectant surface-iodinated proteins. In contrast, substitutions at nearby residues, Gln101, Pro102, and Ile105 did not affect the reactivity of any anti-alpha 4 mAb representing the known alpha 4 epitopes. Homotypic cell aggregation triggered by anti-alpha 4 epitope A mAb was prevented in the transfectants expressing mutated alpha 4 Arg89-Asp90Asp residues, while cell aggregation was fully achieved with either anti-alpha 4 epitope B2 or anti-beta 1 mAb. Mutations at alpha 4 residues Gln101, Pro102, and Ile108 did not affect the homotypic cell aggregation of the transfectants expressing these mutations. In addition, the adhesion of mutant Arg89-Asp90 alpha 4 transfectants to the connecting segment-1-containing fibronectin-40 (FN-40) fragment of fibronectin was diminished compared to wild type alpha 4 transfectants, as well as to other mutant alpha 4 transfectants. This adhesion to FN-40 was restored when the activating anti-beta 1 TS2/16 mAb was present in the adhesion assays. In contrast, adhesion to VCAM-1 was not affected by mutations at Arg89-Asp90, nor at Gln101, Pro102, and Ile108 alpha 4 residues. Altogether, these results indicate that alpha 4 residues Arg89 and Asp90 are included in a region involved in homotypic cell aggregation, as well as in adhesion to FN-40, but not to VCAM-1.

Animals↗
PubMed1996

Sequence of rice hoja blanca tenuivirus RNA-2.

The sequence of rice hoja blanca tenuivirus RNA-2 is analysed and compared to its counter-part in rice stripe tenuivirus. The RNA encodes two proteins, in an ambisense arrangement. The 94 kD pc2, located in the complementary sense RNA, has several features typical of viral membrane (glyco)proteins, and also has regions of local homology to the glycoproteins of the Phleboviruses (Bunyaviridae). The 23 kD pv2 lies in the viral sense RNA and has two small conserved domains that are almost exclusively found in retro-viral membrane glycoproteins. Its genome location is analogous to the NSm protein of several of the Bunyaviridae species, which is thought to have a membrane-related function. The two open reading frames are separated by a large intergenic region which, in common with the other tenuivirus ambisense RNA segments, has a short region that is highly conserved between RStV and RHBV. The significance of these results with respect to the virus structure and gene expression is discussed.

Amino Acid Sequence↗
PubMed1996

Sequence of echinochloa hoja blanca tenuivirus RNA-5.

The sequence is presented of RNA-5 of Echinochloa hoja blanca tenuivirus, a second tenuivirus associated with rice cultivation in Latin America (after rice hoja blanca virus). The RNA is 1334 nucleotides long and contains in the complementary sense RNA a single long open reading frame. The deduced amino acid sequence of this open reading frame shows that it encodes a highly basic and hydrophilic 44 kD protein (pc5) with about 50% similarity to the pc5 protein of maize stripe virus (MStV). This and other features of the RNA are discussed.

Amino Acid Sequence↗
PubMed1996

Sequence of Echinochloa hoja blanca tenuivirus RNA-4.

The sequence is presented of RNA-4 of Echinochloa hoja blanca tenuivirus (EHBV), one of two tenuiviruses associated with rice cultivation in Latin America (together with rice hoja blanca virus; RHBV). Analysis of the sequence shows that the coding regions of EHBV RNA-4 are closely related to those of RHBV RNA-4. However, the intergenic region separating the two ambisense open reading frames, are highly distinct for the two viruses. The features of the RNA and the comparisons with the sequences of RNA-4 of RHBV, rice stripe virus (RStV) and maize stripe virus (MStV) are discussed.

Amino Acid Sequence↗
PubMed1996

Sequence of Echinochloa hoja blanca tenuivirus RNA-3.

Analysis of the sequence of the 2336 nucleotide RNA-3 of Echinochloa hoja blanca tenuivirus shows that it is closely related to RNA-3 of rice hoja blanca tenuivirus, the principal virus disease of rice in Latin America. This is especially true for the coding regions, where the viruses are almost 90% similar. However, the non-coding regions of RNA-3 of these viruses, principally the intergenic region separating the two ambisense open reading frames, are only about 50% similar, suggesting that these are distinct viruses. The results closely resemble those obtained for the analysis of RNA-4 of these viruses, both in the absolute and relative percentage similarities of the coding and non-coding regions. This implies a coordinated evolution of the different tenuivirus RNA segments. The features of the RNA and the comparisons with the sequences of RNA-3 of RHBV, rice stripe virus (RStV) and maize stripe virus (MStV) are discussed.

Amino Acid Sequence↗
PubMed1996

Angiotensin II receptor in human placental syncytiotrophoblast plasma membranes.

Previous studies have reported the presence of high-affinity angiotensin II (Ang II) binding sites in human placental tissue, but it has not been determined whether these are located in brush border (BBM) or basolateral plasma (BPM) membranes of the syncytiotrophoblast. Our findings provide no evidence for Ang II receptors in BBM, yet they reveal a single class of binding sites in BPM preparations (Kd of 4.08+/-0.61 nM and B(max) of 2368.7+/-658.2 fmol/mg protein). Pharmacological characterization also revealed that this receptor was an AT1 receptor subtype. Moreover, isoelectric focusing analysis demonstrated a predominant Ang II-receptor complex migrating to pl 7.0, and two minor receptors at pl 7.2 and 6.5. These data suggest a physiological role of the renin-angiotensin system on syncytiotrophoblast BPM in regulating placental function.

Angiotensin II↗
PubMed1996

Congenital absence of the inferior rectus muscle.

PURPOSE: A healthy 4-year-old boy was seen because of a history of pronounced right head tilt. METHODS: Surgical exploration demonstrated absence of the right inferior rectus muscle. Both horizontal recti muscles were transposed to the normal insertion of the inferior rectus muscle. RESULTS: Six months postoperatively, the boy was orthophoric in the primary and reading positions. CONCLUSIONS: Clinical findings in congenital absence of the inferior rectus may mimic those of an inferior rectus paresis. Orbital computed tomography can assist in the diagnosis.

Child, Preschool↗
PubMed1996

Vertical strabismus after cataract surgery.

PURPOSE: To compare anesthesia methods with resultant strabismus patterns in patients with vertical diplopia after cataract surgery. METHODS: The authors analyzed 28 consecutive patients with acquired vertical diplopia after cataract surgery to identify the strabismus pattern. The method of anesthesia administration was available in 21 patients. Three orbital dissections with simulated retrobulbar blocks were performed on cadavers to ascertain the possibility of injuring the vertical rectus muscles at the time of injection. RESULTS: Fifty percent of the involved muscles were overactive, 39 percent were restricted, and 11 percent were paretic. Eleven patients received retrobulbar, and ten received peribulbar anesthesia. The inferior rectus in 17 patients and the superior rectus muscle in 11 were involved. The odds of damaging the inferior rectus, as opposed to the superior rectus muscle, with peribulbar anesthesia was 4.8 times higher than with retrobulbar blocks. Cadaveric dissections showed the likelihood of direct needle injury to either vertical recti with retrobulbar blocks. CONCLUSIONS: In this patient population, permanent vertical strabismus after cataract surgery results more often from overacting or restricted muscles than from primary muscle paresis. Both the superior and inferior recti can be injured with retrobulbar anesthesia, but peribulbar injections affect the inferior rectus muscle more frequently.

Anesthesia, Local↗
PubMed1996

Role of enteric pathogens in the aetiology of neonatal diarrhoea in lambs and goat kids in Spain.

Faeces samples from diarrhoeic and non-diarrhoeic lambs and goat kids aged 1-45 days were examined for enteric pathogens. Cryptosporidium parvum was detected in both diarrhoeic lambs (45%) and goat kids (42%) but not in non-diarrhoeic animals. F5+ (K99+) and/or F41+ Escherichia coli strains were isolated from 26% and 22% of the diarrhoeic lambs and goat kids, respectively, although these strains, which did not produce enterotoxins ST I or LT I, were found with similar frequencies in non-diarrhoeic animals. A F5-F41-ST I+ E. coli strain was isolated from a diarrhoeic lamb (0.6%). Verotoxigenic E. coli was isolated from both diarrhoeic and non-diarrhoeic lambs (4.1% and 8.2%, respectively) and there was no association between infection and diarrhoea. The prevalence of group A rotavirus infection in diarrhoeic lambs was very low (2.1%). Groups A and B rotaviruses were detected in three (8.1%) and five (13.5%) diarrhoeic goat kids from two single outbreaks. Group C rotaviruses were detected in four non-diarrhoeic goat kids. An association of diarrhoea and infection was demonstrated only for group B rotavirus. Clostridium perfringens was isolated from 10.8% of the diarrhoeic goat kids but not from non-diarrhoeic goat kids or lambs. Salmonella arizonae was isolated from a diarrhoeic goat kid (2.7%) and the clinical characteristics of the outbreaks where these two latter enteropathogens were found different from the rest. Picobirnaviruses were detected in a diarrhoeic lamb. No coronaviruses were detected using a bovine coronavirus ELISA. No evidence was found of synergistic effect between the agents studied. Enteric pathogens were not found in four (8.7%) and three (20%) outbreaks of diarrhoea in lambs and goat kids, respectively.

Age Factors↗
PubMed1996

Utility of C-erbB-2 in tissue and in serum in the early diagnosis of recurrence in breast cancer patients: comparison with carcinoembryonic antigen and CA 15.3.

To evaluate the utility of c-erbB-2, carcinoembryonic antigen (CEA) and CA 15.3 in the early diagnosis of recurrence, serial serum determinations of these antigens were performed in 200 patients (follow-up 1-4 years, mean 2.2 years) with primary breast cancer and no evidence of residual disease (NED) after radical treatment (radical mastectomy or simple mastectomy and radiotherapy). Eighty-nine patients developed metastases during follow-up. C-erbB-2, CEA and CA 15.3 were elevated (> 20 U ml-1, > 10 ng ml-1 or > 60 U ml-1 respectively) before diagnosis in 28%, 30% and 47% of the 89 patients with recurrence, with a lead time of 4.5 +/- 2.4, 4.9 +/- 2.4 and 4.8 +/- 2.4 months respectively. Tumour marker sensitivity was clearly related to the site of recurrence, with the lowest sensitivity found in locoregional relapse and the highest in patients with liver metastases. When patients with locoregional recurrences were excluded, sensitivity improved: 31% (c-erbB-2), 33% (CEA) and 56% (CA 15.3), with 76% having at least one of the three tumour markers. C-erbB-2 sensitivity in early diagnosis was significantly higher in patients with c-erbB-2 overexpression in tissue (8/10, 80%) than in those without overexpression (1/30, 3.3%) (P = 0.0001). Likewise, higher levels of both, c-erbB-2 and CA 15.3 at diagnosis of recurrence, higher sensitivity in early diagnosis of relapse and a higher lead time were found in PR+ patients (CA 15.3, P < 0.0001) or in PR- patients (c-erbB-2, P = 0.009). Specificity of the tumour markers was 100% for all three markers (111 NED patients). In conclusion, c-erbB-2 is a useful tool for early diagnosis of metastases, mainly in those patients with c-erbB-2 overexpression in tissue. Using all three markers simultaneously it is possible to increase the sensitivity in the early diagnosis of recurrence by 11.2%.

Bone Neoplasms↗
PubMed1996

Treatment of multiple myeloma in elderly people: long-term results in 178 patients.

The purposes of the present study have been to analyse the presenting features, response to therapy and survival of myeloma patients aged 70 years or more, in comparison to younger patients. From January 1985 to December 1989, 487 patients with multiple myeloma (MM) were randomized to receive melphalan and prednisone (MP) versus alternating cycles of vincristine, cyclophosphamide, melphalan, and prednisone (VCMP) and vincristine, BCNU, adriamycin, and prednisone (VBAP). The subset of 178 patients who were 70 or more years is the subject of this study, whereas the 309 patients younger than 70 years were used as a control group. The presenting features and response to chemotherapy of older patients were no different to those of the younger population. However, the survival of elderly patients was significantly shorter (median 23.4 vs. 33.5 months, p < 0.001). The overall response rate to MP in older patients was 50% (28% objective plus 22% partial response) compared with 61% (44% objective plus 17% partial response) to combination chemotherapy (p = not significant). Myelosuppression was moderate in both arms, although MP produced a higher degree of thrombocytopenia. There were no significant differences in survival between patients given MP versus VCMP/ VBAP (median, 20 vs. 27 months, p = 0.2). Response to treatment was associated with a significantly longer survival. Older patients with symptomatic myeloma tolerate chemotherapy and should be offered treatment.

Age Factors↗
PubMed1996

Evidence for an anuran homologue of the mammalian spinocervicothalamic system: an in vitro tract-tracing study in Xenopus laevis.

Evidence is presented for an anuran homologue of the mammalian spinocervicothalamic system. In vitro tract-tracing experiments with biotinylated dextran amine Xenopus laevis show that ascending spinal fibres from all levels of the spinal cord, passing via the dorsolateral funiculus, terminate in a cell area ventrolateral to the dorsal column nucleus. This cell area can be considered a possible homologue of the mammalian lateral cervical nucleus. After tracer applications to the ventral thalamus or to the torus semicircularis (both targets for somatosensory projections), the anuran lateral cervical nucleus was retrogradely labelled contralateral to the application sites. Tracer applications to the dorsolateral funiculus at the obex level and rostral spinal cord resulted in labelling of the cells of origin of the spinocervical tract. These were found, mainly ipsilaterally, in the ventral part of the dorsal horn, and were rather evenly distributed throughout the spinal cord. These data suggest the presence of an anuran homologue of the mammalian spinocervicothalamic system. A brief survey of the literature shows that such a system is much more common in vertebrates than previously thought.

Afferent Pathways↗
PubMed1996

Detection of circulating neoplastic cells by reverse-transcriptase polymerase chain reaction in malignant melanoma: association with clinical stage and prognosis.

PURPOSE: Circulating melanoma cells can be detected in peripheral blood by means of tyrosinase mRNA amplification by reverse-transcriptase polymerase chain reaction (RT-PCR). We conducted a prospective study to evaluate the clinical significance of the presence of circulating neoplastic cells in the blood of patients with malignant melanoma (MM). METHODS: A sensitive RT-PCR assay was used to detect tyrosinase mRNA in the peripheral blood of patients with stages I to IV melanoma. Healthy subjects or patients with other malignancies were used as negative controls. RESULTS: Ninety-one assessable patients were included in the study. There was a statistically significant association between RT-PCR positivity and clinical stage. Circulating melanoma cells were detected in 36% of patients with localized disease (stages I and II), in 45% of patients with regional nodal involvement (stage III), and in 94% of patients with metastatic disease (stage IV) (P < .001). In stage II-III patients who were RT-PCR-positive for mRNA tyrosinase in blood, the recurrence rate and disease-free survival were significantly worse than patients who were RT-PCR-negative. In multivariate analysis, RT-PCR was an independent prognostic factor for recurrence in patients with nonmetastatic disease (P = .002). CONCLUSION: The detection of circulating melanoma cells in peripheral blood by RT-PCR correlated with the clinical stage of patients with melanoma and was an independent prognostic factor for recurrence. Further studies are warranted to better assess the significance of this test in the evaluation of prognosis, early detection of relapse, and in monitoring the effectiveness of systemic therapy.

Adult↗