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Biomedical subjects

G Rodriguez

Publications and source records attributed to G Rodriguez.

At least 127 records · Page 7Linked to original sources
PubMed1991

Judo and choking: EEG and regional cerebral blood flow findings.

Ten judoka were examined at rest by EEG and regional Cerebral Blood Flow (rCBF) (133-Xenon inhalation method); in seven of them a syncope was induced by choking and EEG was recorded during the loss of consciousness while rCBF was measured immediately after recovery. Baseline EEG and rCBF examinations were normal. During choking, EEG showed diffuse 2-3 Hz. high voltage waves, predominantly in the anterior regions, then the EEG gradually recovered to normal. After choking, rCBF decreased in all but one subject, slightly in four and more markedly in two. Our findings suggest that there is no evidence of permanent CNS functional changes due to judo practice and choking. The variable rCBF features soon after choking-induced syncope may reflect a different timing of recovery from cerebral ischemia for each subject.

Adolescent↗
PubMed1990

Regional cerebral blood flow after omental transposition to the ischaemic brain in man. A five year follow-up study.

Regional cerebral blood flow, recorded by the 133Xenon inhalation method, was measured preoperatively and over a five years postoperative period in six patients with completed stroke and stabilized neurological deficits, who had undergone omental transposition for revascularization of the ischaemic brain. Comparisons of the preoperative blood flow values with those recorded following surgery demonstrate a postoperative increase of blood flow in five patients, with a high statistical degree of significance in four of them at the final examination. The flow increase was noted over the infarcted areas of the brain, upon which the omentum had been placed, as well as areas of the ischaemic hemisphere without omental placement and the contralateral hemisphere. Out of the five patients who demonstrated preoperative flow values below the expected norm for age, four showed final postoperative cerebral blood flow within the normal limits for their age. The results are consistent with the assumption that the transposed omentum played a role in postoperative blood flow increase, by adding collateral circulation to the ischaemic brain.

Adolescent↗
PubMed1990

Primary dysautonomia: cerebral blood flow and hemodynamic findings. Case report.

In a man with orthostatic and effort syncopes due to primary dysautonomia, we measured cerebral blood flow (CBF)--by the 133-Xenon inhalation method--in supine and in sitting positions, and after the i.v. administration of Acetazolamide, a potent cereal vasodilator. Heart rate (HR) and blood pressure (BP) were monitored over the 24 hours by a non-invasive device. The CBF was normal in supine position and significantly reduced when the patient was sitting. Despite che sympathetic denervation, good response to acetazolamide infusion was seen. BP changed with the position of the subject according to gravity, and HR was unresponsive to orthostatic and effort stimuli.

Acetazolamide↗
PubMed1990

Effect of electron withdrawing substituents on substrate hydrolysis by and inhibition of rat neutral endopeptidase 24.11 (enkephalinase) and thermolysin.

A series of N-acylphenylalanylglycine dipeptides were synthesized and examined as substrates for neutral endopeptidase 24.11 (NEP) and thermolysin. Those N-acyl dipeptides containing an N-acyl group derived from an acid whose pKa is below 3.5 were considerably more reactive with both enzymes than those peptides containing an N-acyl group derived from an acid whose pKa is above 4. The data are interpreted to suggest that electron withdrawal at the scissile bond increases kappa cat for both NEP and thermolysin. The pH dependence for inhibition by the dipeptides Phe-Ala, Phe-Gly, and Leu-Ala showed binding dependent upon the basic form of an enzyme residue with a pKa of 7 for NEP and a pKa of 6 for thermolysin. In the case of thermolysin this pKa was decreased to 5.3 in the enzyme-inhibitor complex. When examined as alternate substrate inhibitors of NEP, N-acyl dipeptides showed three distinct profiles for the dependence of Ki on pH. With N-trifluoroacetyl-Phe-Gly as inhibitor, binding is dependent upon the basic form of an enzyme residue with a pKa value of 6.2. N-methoxyacetyl-Phe-Gly inhibition appears pH independent, while N-acetyl-Phe-Gly inhibition is dependent upon the acidic form of an enzyme residue with a pKa of approximately 7. All inhibitions of thermolysin by N-acyl dipeptides exhibit a dependence on the acidic form of an enzyme residue with a pKa of 5.3 to 5.8. These results suggest that with NEP, binding interactions at the active site involve one or more histidine residues while with thermolysin binding involves an active site glutamic acid residue.

Acylation↗
PubMed1990

Kinetic and inactivation studies of recombinant Drosophila choline acetyltransferase.

A cDNA for Drosophila choline acetyltransferase (ChAT) was expressed in E. coli and the recombinant enzyme partially purified. Kinetic analysis yielded the following constants for the recombinant enzyme; KmAcCoA = 29 microM, KmCoA = 25 microM, Kmcholine = 330 microM, and Kmacetylcholine = 2 mM. The recombinant Drosophila enzyme, like the enzyme from other species, exhibited an increase in activity as a function of increased salt concentration. Chemical modification studies using dithio-bis-nitro-2-carboxylate, butanedione, and diethylpyrocarbonate showed that the recombinant enzyme contains active site cysteine, arginine, and histidine residues. These studies demonstrate that the recombinant Drosophila ChAT possesses the same catalytic properties as the enzyme from a variety of other sources.

Animals↗
PubMed1990

Regional cerebral blood flow in schizophrenia: repeated studies during a psychotic episode.

Regional cerebral blood flow (rCBF) measurements and clinical ratings were performed on 17 schizophrenic patients and a subgroup of 10 medication-free patients before and after treatment. While clinically exacerbated patients had normal blood flow, patients in remission showed a redistribution of flow with lower values in frontal areas. Anteroposterior ratios correlated with the degree of behavioral disturbances, suggesting that the level of frontal lobe activity in schizophrenia may be a function of the patient's clinical state at the time of study.

Adult↗
PubMed1990

Distribution and etiology of leishmaniasis in Colombia.

A total of 340 Leishmania strains, isolated from humans, animals, and sand flies from various regions of Colombia, were examined by isozyme electrophoresis. Seven different Leishmania species were identified. Leishmania panamensis and L. braziliensis were the most common, representing 53.8% and 30.3% of the total, respectively. Isolation rates of the other species were as follows: L. chagasi, 9.4%; L. guyanensis, 2.6%; L. amazonensis, 1.8%; L. mexicana, 0.8%; and a new species requiring additional study, 1.2%. Statistical analyses of representative L. panamensis and L. braziliensis isolates indicated that the populations of these 2 species are genetically very similar. L. panamensis may have a continuous distribution in Colombia west of the eastern Andes Mountains and L. braziliensis may have a continuous distribution east of the western Andes Mountains. Information is given on disease manifestations of the parasites in human hosts and on isolation records from sand flies and animals.

Animals↗
PubMed1990

Expression of epidermal growth factor receptor and HER-2/neu in normal and neoplastic cervix, vulva, and vagina.

Monoclonal antibodies were used to localize immunohistochemically epidermal growth factor receptor and HER-2/neu in normal and neoplastic frozen tissue samples from the lower genital tract of women. In squamous epithelia of the cervix, vulva, and vagina, epidermal growth factor receptor and HER-2/neu both were expressed most strongly by basal keratinocytes. Expression of both of these cell surface molecules decreased as cells underwent differentiation toward the mucosal surface. In contrast, both epidermal growth factor receptor and HER-2/neu were expressed throughout the entire thickness of the epithelium by undifferentiated squamous cells in squamous metaplasia, raised condyloma, and carcinoma in situ. In 34 squamous cancers of the cervix, vulva, and vagina, all malignant cells were found to have moderate to heavy staining for epidermal growth factor receptor. Staining of 33 of these cancers for HER-2/neu was light, although one patient who presented with distant metastases had heavy staining for HER-2/neu. These data suggest that although overexpression of HER-2/neu in squamous cancers of the lower genital tract is a rare event, it may be associated with aggressive biologic behavior.

Adenocarcinoma↗
PubMed1990

Acute effects of acetyl-L-carnitine on regional cerebral blood flow in patients with brain ischaemia.

Ten male patients with brain ischaemia were studied. Regional cerebral blood flow (rCBF) was measured in the resting condition and 1 h after intravenous infusion of 1500 mg acetyl-L-carnitine. rCBF values were compared to those of a control population of the same age decade by a computer mapping system of our own design, which enables rapid visual inspection of cerebral blood flood values distribution and of statistical significance of differences. Beneficial effects of the drug were observed in at least four patients, especially in the affected hemisphere, in another four, rCBF elevations in the areas which were lowest on resting examination were observed, which was paralleled by reductions in surrounding zones. In two patients no modification of rCBF values after acetylcarnitine was seen.

Acetylcarnitine↗
PubMed1990

[Perspectives of liver transplantation in Chile].

After an initial experience with 4 patients who received orthotopic liver transplant (OLT) we analyze the perspectives of establishing liver transplantation programs in Chile. An estimated 100 adult and pediatric patients require OLT a year and no more than 3 centers are required to deal with this and acquire experience with the procedure. A national organization for organ procurement is essential, given the marked difficulties in obtaining cadaver organs at present. Each procedure has an estimated cost of $5 million with 2 more millions in the first year. Thus a program for 15 patients a year may cost $ 100 million, personnel expenses not included.

Adult↗
PubMed1989

Inhibition of the yeast-mycelial transition and the phorogenesis of Mucorales by diamino butanone.

Diamino butanone (DAB), a competitive inhibitor of ornithine decarboxylase (ODC) a key enzyme in polyamine biosynthesis, inhibited the yeast to hyphae transition in Mucor rouxii, induced by transfer from anaerobiosis to aerobiosis, but not the opposite phenomenon. Addition of DAB to anaerobic yeast cells brought about a decrease in ODC and polyamine levels. In these conditions, the aerobic shift produced only a weak increase in ODC activity and no change in polyamine levels. DAB also blocked phorogenesis in M. rouxii and in Phycomyces blakesleeanus. At the effective concentrations DAB did not affect cell growth of either fungus. It is suggested that low, constant levels of ODC and polyamines are necessary for cell growth, and that high transient levels are required during the differentiative steps. DAB, at the concentrations used, affects this last process, but does not interfere with the maintenance level of polyamines.

Cell Differentiation↗
PubMed1989

Cerebral blood flow and plasma free tryptophan in cirrhotics with and without hepatic encephalopathy.

Cerebral blood flow (CBF), measured by the non-invasive 133-Xenon inhalation method, plasma levels of ammonia (NH3) and free tryptophan (fTRP) were determined in 30 cirrhotic patients without overt encephalopathy. Psychometric evaluation detected subclinical hepatic encephalopathy (SHE) in 20 of them, and was normal in the other 10. A significant CBF difference (p less than 0.05) was found between the SHE and the non-SHE patients. fTRP levels were significantly (p less than 0.05) higher in patients with SHE than in those without SHE, and a significant negative correlation (p = 0.003) was found between CBF values and fTRP in the whole group of patients. NH3 did not differ in the two subgroups and did not correlate with CBF values. It is concluded that CBF could have some implications in SHE, although its relevance is still unclear. The negative correlation between CBF and fTRP prompts further investigation concerning the relationships between plasma fTRP, brain serotonin, cerebral metabolism and blood flow in the development of brain derangement during cirrhosis.

Adult↗
PubMed1989

Food-borne disease in hospitals: prevention in a changing food service environment.

The results of an investigation into an outbreak of food-borne disease at a hospital in Los Angeles County are reported. The outbreak occurred at a luncheon buffet for nonpatient visitors attending an event at the hospital, which was catered by the hospital. The food source and etiologic agent(s) responsible for the outbreak were not identified by our investigation. However, several issues relating to the changing character of hospital food provision and their implications for prevention of food-borne disease in hospitals were conspicuous. Two trends apparent in hospital food service are toward increased use of foodstuffs prepared by wholesale food manufacturers and more frequent invitation to community groups to meet within hospital facilities and use hospital catering services. We found that (1) hospital kitchens in Los Angeles County are undersurveyed with respect to frequency of sanitary inspections; (2) hospitals have no mechanism whereby to assess the sanitary inspection record of wholesale food manufacturers from whom they purchase foodstuffs; and (3) crossover of food items prepared for nonpatient hospital visitors, including catered foods, to the inpatient menu occurs. The potential risks for a food-borne disease outbreak among compromised inpatients resulting from these factors are discussed, and measures to reduce such risk are proposed.

Community-Institutional Relations↗
PubMed1989

Regional cerebral blood flow and anxiety: a correlation study in neurologically normal patients.

Regional CBF (rCBF) was evaluated by the 133Xe inhalation method in 60 neurologically normal patients (30 men and 30 women) and hemispheric and regional values were correlated with anxiety measurements collected by a self-rating questionnaire before and after the examination. Statistically significant negative correlations between rCBF and anxiety measures were found. rCBF reduction for high anxiety levels is in line with results previously reported by others and could be related to lower performance levels for moderately high anxiety scores as those reported in the present population. This could perhaps be explained by rearrangement of flow from cortical zones to deeper areas of the brain, classically known to be implicated in the control of emotions. However, these results should be interpreted cautiously, since they were obtained in patients and not in normal subjects.

Adult↗
PubMed1989

Evaluation of cerebral blood flow data in stroke patients using a mapping system.

We retrospectively examined regional cerebral blood flow values in 78 patients in the stabilized phase of stroke to evaluate the consistency of lateralization compared with computed tomographic imaging. Examinations were performed using the xenon-133 inhalation technique, and the data were processed and displayed by a computer-assisted system of our own design that allows statistical analysis in real time and is suitable for clinical use. The consistency of lateralization correlated with computed tomographic findings was tested for absolute values, percent distribution, and asymmetries. The latter yielded the highest degree of sensitivity (in 83.3% of the patients the affected hemisphere was correctly identified). Absolute values showed at least one hypoperfused area in the affected hemisphere in 48.7% of the patients, and percent distribution did so in 57.7%. Furthermore, the combination of the three methods of data analysis yielded a sensitivity of 91%; the remaining 9% of the patients, however, exhibited some abnormalities of regional cerebral blood flow (bilateral or contralateral hypoperfusion). Although good agreement was found for lateralization by computed tomography and by the combined use of the three methods of analysis, a complete overlap between functional and structural examinations should not be expected. Problems concerning the sensitivity of the xenon-133 inhalation technique under conditions of low blood flow and the statistical analysis of regional cerebral blood flow data are discussed.

Administration, Inhalation↗
PubMed1988

Sex differences in regional cerebral blood flow.

Regional cerebral blood flow was measured by the 133-xenon inhalation method during resting in 38 healthy men and 38 healthy women matched pairwise for age in the range 18-72 years. The results showed 11% higher global flow level in the women in all ages. A similar and significant regression of flow by age was seen for both sexes. The regional flow distribution also showed some sex-related differences. Frontal regions showed an asymmetry in the men with higher values on the right side. The female flows were more symmetric. As a hypothesis, it is suggested that the higher flow level in women may be a systemic phenomenon. In fact, other authors have found a higher cardiac index in females. The sex differences in regional flow pattern might be due to differences in the functional organization of the cortex and/or to differences in the mental processes of the "resting" state.

Adolescent↗