PubMed Health⌕ Search

Biomedical subjects

R Rodríguez

Publications and source records attributed to R Rodríguez.

At least 235 records · Page 13Linked to original sources
PubMed1989

Oxidation of Neurospora crassa NADP-specific glutamate dehydrogenase by activated oxygen species.

The glutamine synthetase and the NADP-specific glutamate dehydrogenase activities of Neurospora crassa were lost in a culture without carbon source only when in the presence of air. Glutamine synthetase was previously reported to be liable to in vitro and in vivo inactivation by activated oxygen species. Here we report that NADP-specific glutamate dehydrogenase was remarkably stable in the presence of activated oxygen species but was rendered susceptible to oxidative inactivation when chelated iron was bound to the enzyme and either ascorbate or H2O2 reacted on the bound iron. This reaction gave rise to further modifications of the enzyme monomers by activated oxygen species, to partial dissociation of the oligomeric structure, and to precipitation and fragmentation of the enzyme. The in vitro oxidation reaction was affected by pH, temperature, and binding to the enzyme of NADPH. Heterogeneity in total charge was observed in the purified and immunoprecipitated enzymes, and the relative amounts of enzyme monomers with different isoelectric points changes with time of the oxidizing reaction.

Aerobiosis↗
PubMed1989

CNS effects of platelet-activating factor on the rat stomach.

PAF has been implicated in the pathogenesis of acute gastric injury. When administered peripherally, PAF induces severe gastric mucosal damage. PAF-metabolizing enzymes are present in the brain, but the central effects of PAF on the stomach are unknown. We have investigated gastric secretory and mucosal response to i.c.v. PAF in the rat and compared it with that of i.c.v. thyrotropin-releasing hormone (TRH), a known central gastric secretagogue. Gastric acid output was markedly increased by TRH (171.6 +/- 26.3 mumol/h mean +/- SE) and by 20 micrograms/kg/h i.v. pentagastrin (107.6 +/- 23.6), as compared to controls receiving i.c.v. vehicle (20.2 +/- 7.5; p less than 0.01 for both). In contrast, acid output decreased after i.c.v. PAF (13.5 +/- 7.5). Furthermore, i.c.v. PAF markedly inhibited acid output stimulated by i.v. pentagastrin (45.1 +/- 7.03; p less than 0.05). Morphologic studies showed acute gastric mucosal erosions after i.c.v. TRH, but no damage was observed after i.c.v. PAF or vehicle. Thus, i.c.v. PAF inhibits gastric acid secretion but does not alter gastric mucosal integrity, whereas i.c.v. TRH stimulates acid secretion and induces gastric injury. The opposite effects of PAF and TRH suggest the existence of a gastric modulatory system at the central level.

Animals↗
PubMed1989

[Influence of the degree of saturation of iron stores on the gastrointestinal absorption of aluminum].

The possible influence of iron metabolism in the regulation of aluminum gastrointestinal absorption in male Wistar rats has been studied. Three groups were considered: Fe overloaded Group 1; Fe normal Group 2; Fe depleted Group 3. All groups were exposed during 45 days to 40 mg of Al(OH)3 investigating the concentration of Al in serum and urine throughout the experiment and also the Al in brain at the end of that period. Results demonstrated that 24 h urinary Al excretion was significantly higher in Fe depleted rats than in Fe overloaded animals (p less than 0.01 and p less than 0.05 respectively). In addition, Al in brain showed the same pattern of deposition yielding in the Fe depleted rats nearly a three fold increase in the concentration of Al. By contrast, serum Al did not show any particular trend. These findings are in agreement with the fact that Fe metabolism may modulate Al gastrointestinal absorption suggesting that Al and Fe might share the same mechanism of gastrointestinal absorption.

Aluminum↗
PubMed1989

[Combination of interstitial implants of Au-198 seeds and external irradiation in the treatment of prostatic carcinoma. Preliminary communication].

The usefulness of external and interstitial radiotherapy in the treatment of prostatic carcinoma is well-documented. We report on our experience in 23 cases using interstitial Au-198 seed implants in combination with external radiation. The diagnostic protocol and therapeutic approach are described. Local control was achieved in 73% and the disease-free survival at 36 months was 49%. The mean follow-up was 44 months. The problems resulting from TUR and the different factors that might be responsible for the failure of local treatment are discussed.

Aged↗
PubMed1989

[Radiotherapy as the definitive treatment of patients with carcinoma of the bladder].

Sixty-one patients, who refused surgery or whose overall medical status advised against radical cystectomy, were submitted to radical radiotherapy at the Oncology Radiotherapy Service of the General Hospital of Asturias. Irradiation was performed in a cobalt therapy unit. Radiation dose ranged from 50-70 Gy, with a daily dose of 190-200 cGy. Local control was achieved in 71% for stage A, 68% for B1. 17% for B2, and 0% for stage C. Disease-free survival was 63% for stage A, 48% for B1, 14% for B2, 0% for C, and 17% for D1. Overall disease-free survival was 20%, and the morbidity and mortality rates were 11.4% and 3.2%, respectively. In view of the poor results achieved in our setting, we have considered using combined external and interstitial radiation for tumors localized in the muscle layer, and adjuvant chemotherapy for stage C tumors (or those infiltrating perivesical fat).

Aged↗
PubMed1988

Primary structure of the major allergen of yellow mustard (Sinapis alba L.) seed, Sin a I.

Sin a I, a 2-S albumin from the seeds of yellow mustard, is herein described as the major allergen of these seeds. This protein is composed of two disulfide-linked polypeptide chains of 39 and 88 amino acids, whose primary structures are reported. The Sin a I allergen is found to be related to other low-molecular-mass albumins, such as those isolated from rapeseed, castor bean and Brazil nut. Additional structural similarity has also been found between the glutamine-rich large chain of Sin a I and a proline-rich zein, a gliadin, and trypsin and alpha-amylase inhibitors isolated from the seeds of several monocotyledons. Internal amino acid sequence similarity has been detected at both termini of the small and large chains of Sin a I and involves the location of proline and glycine residues at similar positions in relation to the processing cleavage sites. Prediction of secondary structure, based on the amino acid sequences of the mature chains of the mustard allergen, indicates that the precursor polypeptide is cleaved at regions showing a high beta-turn probability. This is also observed with the amino acid sequence deduced from the rapeseed napin gene nucleotide sequence.

Allergens↗
PubMed1988

Comparative study of electrophoretic patterns of latex proteins from clones of Hevea brasiliensis.

Latex serum proteins from Hevea brasiliensis were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Proteins from whole serum and fractions isolated by gel chromatography on Ultrogel AcA 44 were analyzed. No qualitative clonal differences were found in the protein patterns of whole latex or in the fractions but laser densitometry revealed reliable quantitative differences in protein composition. Reproducible mobilities and molecular weights of selected bands were obtained both within single gels as well as in different gels, analyzing several lots of latex received at various times from a Hevea experimental field station. The clones compared were IAN 710, GV 31, GV 42; the first one had the highest rubber yields.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Electrocardiographic alterations induced by repeated electrical stimulation of the heart at low intensity.

Repeated, low-intensity electrical stimulation of the heart gradually leads to the development of electrocardiographic abnormalities that culminate in cardiac arrhythmias, mainly A-V block in the isolated heart frog and ventricular and supraventricular tachyarrhythmias in the canine heart in situ. The pattern of development of these alterations shows some characteristics similar to the kindling phenomenon. Blockade of adrenergic influences on the heart offered complete protection against the development of cardiac arrhythmias. These results support the idea that a kindling-like effect can be induced by the periodic electrical stimulation of structures other than the CNS.

Animals↗
PubMed1988

Conservative treatment of early breast cancer.

At our Institution, the treatment policy for early carcinoma of the breast (T1-2, NO, AJC) is lumpectomy followed by radiotherapy to the breast and peripheral lymphatics. From October 1976 until December 1982, 171 patients have been admitted and treated. Radiotherapy was administered with 60 Co, 5.000 cGy in 5 weeks to the breast and lymphatics plus a boost to the scar giving q.s.p. 6.400 cGy at maximum tumor depth. With a minimum follow-up of 3 years and a median follow-up of 61.7 months the locoregional control was 94.2% and survival at 8 years with no evidence of disease (NED) was 77.2% with an overall survival rate of 90%. No difference in NED survival rate was found between Stage I and II. There was a tendency to better survival rate in those patients older than 50 years and also for post menopausal patients, however the difference did not reach statistical significance (66.7% NED survival at 8 years for premenopausal and 81.8% NED survival for post menopausal, also at 8 years, p = 0.056 Gehan). The time elapsed between surgery and radiation therapy (between 1 and 2 months) was found to be nonsignificant. Only 1 out of 171 patients had axillary dissection. The importance or lack of it, is discussed.

Breast Neoplasms↗
PubMed1988

[Effects of cranial radiotherapy on growth and hypothalamo-hypophyseal function].

Aiming at evaluating the possible adverse effects of the use of radiotherapy on the CNS in children, we studied fourteen patients in whom it was used: seven as part of the conventional prophylaxis we use in malignant lymphoproliferative processes (group I) and the remaining seven as a treatment for primary cerebral tumors (group II). We evaluated growth during periods ranging from 1.5 to 11 years, and also hypothalamic-pituitary function by RIA. We comment on the results and confirm the endocrine alterations, especially the deficit of growth hormone.

Brain Neoplasms↗
PubMed1988

[Effects of the use of cranial radiotherapy. Findings obtained by computerized axial tomography and intellectual function tests].

Authors report their brain computerized axial tomography findings (CAT) and intellectual performance, in fourteen children treated with cranial radiotherapy either as part of conventional prophylaxis with intrathecal methotrexate use in malignant lymphoproliferative processes or as treatment for a primitive cerebral tumor. They comment on myelinating leukoencephalopathy and neuropsychologic sequelae that can appear.

Astrocytoma↗
PubMed1987

Relationship between hydropathic variability and functional properties of alpha-lactalbumins and type c lysozymes.

Hydropathic profiles obtained from the amino acid sequences of 8 alpha-lactalbumins were averaged and compared to the average profile deduced from the primary structure of 21 type c lysozymes. This analysis was performed in order to detect differences between both types of molecules, since it could explain their different functional properties. The application of the method herein described reveals the existence of very significative differences (P less than 0.001) between the amino acid residues located at positions 31-32, 34-35, 37-45, 47-48, 80-85 and 108-113 of alpha-lactalbumins and their homologous in type c lysozymes. These differences are in agreement with the chemical data about the interaction sites of both galactosyltransferase and calcium ions with alpha-lactalbumin, which are not required for the lysozyme function.

Amino Acid Sequence↗
PubMed1987

Kindling-like convulsive activities in the isolated ileum of the guinea pig. I. Electrical stimulation.

A kindling-like convulsive activity model produced by subthreshold, iterative electrical stimulation of the isolated male guinea pig ileum is described. In this model, the mechanical activity of the longitudinal muscular fibers of the ileum was systematically quantified in terms of the basic frequency, tonus, amplitude, and transient amplitude increments (A, n spikes/20 min) of "normal" contractions and presence of high-amplitude, paroxysmal, "epileptiform" contractures (B, n spikes/20 min). Changes in these parameters were statistically compared through consecutive stages of the same stimulated male ileum (I = initial activation, II = initial inhibition. IIIA = late activation, and IV = late inhibition) and equivalent stages of stimulated female and nonstimulated male ilea where "kindling-like" activities were only occasionally observed. Basic tonus, amplitude, and number of A spikes showed significant changes through consecutive stimulated male ileum "kindling" stages: increased from baseline to stage I, decreased from I to II, increased from II to III and from III to IIIA, and decreased from IIIA to IV. The number of B spikes significantly increased from II to III, III to IIIA, and IIIA to IV. No significant changes in baseline frequency were found through all stages nor in tonus, amplitude, A and B spikes between stage IV and the self-sustained activity observed 120 min after stimulation. In addition, there were significant correlations between B spikes vs. basic tonus and amplitude and A spikes when the stimulated male ileum shifted from stage II to IIIA (positive correlations) and from IIIA to IV (negative correlations). Basic tonus during stage I, basic amplitude during IIIA, A spikes during self-sustained activity and B spikes during III, IIIA, IV, and self-sustained activity were in the stimulated male ileum larger than those in both the stimulated female and the nonstimulated male ilea. Tonus and A spikes during III and IIIA in the stimulated male ileum were larger than in the nonstimulated, whereas tonus during IV and self-sustaining activity and amplitude during II in the stimulated male ileum were smaller than in the female stimulated ileum.

Animals↗
PubMed1987

Structure of the pigeon lysozyme and its relationship with other type c lysozymes.

1. The secondary structure of the pigeon egg-white lysozyme shows important differences when compared to other type c lysozymes. These differences are mainly located at the region comprising residues 77-84. This segment contains one alpha-helix in the lysozymes c studied by means of an X-ray analysis, while the residues at such positions in pigeon lysozyme would form two beta-bends. 2. Analysis of the tertiary structure of the pigeon lysozyme by means of hydropathy profiles reveals that the above segment seems to be more hydrophilic in the pigeon enzyme than in other type c lysozymes. 3. Though a certain similarity to the calcium-binding loop of alpha-lactalbumins is detected in pigeon lysozyme, the circular dichroism spectra of the protein at neutral pH do not change in the presence of Ca2+ ions. 4. The presented structural analysis is discussed in terms of function-structure and antigenicity relationships between the type c lysozymes.

Animals↗