Search PubMed⌕ Search

Biomedical subjects

J Miranda

Publications and source records attributed to J Miranda.

At least 73 records · Page 4Linked to original sources
PubMed1994

Nodulating ability of Rhizobium tropici is conditioned by a plasmid-encoded citrate synthase.

Rhizobium species elicit the formation of nitrogen-fixing root nodules through a complex interaction between bacteria and plants. Various bacterial genes involved in the nodulation and nitrogen-fixation processes have been described and most have been localized on the symbiotic plasmids (pSym). We have found a gene encoding citrate synthase on the pSym plasmid of Rhizobium tropici, a species that forms nitrogen-fixing nodules on the roots of beans (Phaseolus vulgaris) and trees (Leucaena spp.). Citrate synthase is a key metabolic enzyme that incorporates carbon into the tricarboxylic acid cycle by catalysing the condensation of acetyl-CoA and oxaloacetic acid to form citrate. R. tropici pcsA (the plasmid citrate synthase gene) is closely related to the corresponding genes of Proteobacteria. pcsA inactivation by a Tn5-mob insertion causes the bacteria to form fewer nodules (30-50% of the original strain) and to have a decreased citrate synthase activity in minimal medium with sucrose. A clone carrying the pcsA gene complemented all the phenotypic alterations of the pcsA mutant, and conferred Rhizobium leguminosarum bv. phaseoli (which naturally lacks a plasmid citrate synthase gene) a higher nodulation and growth capacity in correlation with a higher citrate synthase activity. We have also found that pcsA gene expression is sensitive to iron availability, suggesting a possible role of pcsA in iron uptake.

Agrobacterium tumefaciens↗
PubMed1993

Visual evoked potentials and electroretinography in brain-dead patients.

Visual evoked potentials and electroretinograms were elicited by light-emitting diode stimulation and recorded simultaneously, with cephalic and noncephalic references, in 30 normal subjects and in 30 brain-dead patients. A characteristic pattern was found in the group of patients: when a cephalic reference was used for both visual evoked potentials and the electroretinogram, the a- and b-waves of the electroretinogram were recognized in all patients, and visual evoked responses consisted of waves with inverse polarity, similar morphologic characteristics, the same latency, and less amplitude than those of the electroretinogram. When a noncephalic derivation was chosen for the electroretinogram and visual evoked potentials, electroretinogram did not change in either morphologic features or latency, whereas the visual evoked potential channel showed no response. Only in two cases was it possible to record waves in the visual evoked potential lead with a noncephalic reference, showing a spread of the electroretinogram to the occipital area, with a considerably reduced amplitude. These results suggest that, although contamination of visual evoked potential records by the spread of the electroretinogram to the occipital area could occur, it is easy to confirm the absence of a true cortical visual response in brain-dead patients by means of a noncephalic reference. This pattern clearly confirms that in the visual pathways of brain-dead patients, electrical activity is confined to the retina.

Adolescent↗
PubMed1993

Relationships between symptoms of depression and anxiety and dysfunctional beliefs about achievement and attachment.

Psychiatric outpatients (N = 293) provided data to test the symptom specificity and final common pathway hypotheses about symptoms of depression and anxiety. The symptom specificity hypothesis predicts that the symptoms reported by a depressed or anxious patient depend on the dysfunctional beliefs he or she endorses. In contrast, the final common pathway hypothesis predicts that symptoms are unrelated to the types of beliefs the patient endorses. These hypotheses were tested in the context of theories that emphasize the importance of dysfunctional beliefs about achievement and attachment. Only limited support for the symptom specificity hypothesis was obtained; support was strongest for the link between attachment beliefs and anxiety symptoms. Relationships between symptoms and dysfunctional beliefs did not depend on psychiatric diagnosis.

Achievement↗
PubMed1993

DSM-III-R disorders in Vietnamese refugees. Prevalence and correlates.

This study's purpose was a) to determine the prevalence of DSM-III-R disorders in newly arrived ethnic Vietnamese and ethnic Chinese refugees from Vietnam and b) to determine the correlates of DSM-III-R disorders. A Vietnamese-speaking psychiatrist administered translated sections of the Structured Clinical Interview for DSM-III-R to 201 Vietnamese new arrivals undergoing mandatory health screening. Overall, 18.4% had one or more current disorders: 8.5% had adjustment disorder and 5.5% had major depression. Ethnic Vietnamese, compared with ethnic Chinese, had significantly (p < .05) higher rates of current posttraumatic stress disorder and generalized anxiety disorder. Ethnic differences in psychopathology were largely explained by the fact that ethnic Vietnamese refugees had experienced more traumatic events and separation from family. After adjusting for ethnicity, refugees who reported traumatic events, refugees who were married, and veterans were significantly (p < .05) more likely to have one or more psychiatric disorders.

Adult↗
PubMed1993

Short latency somatosensory evoked potentials in brain-dead patients using restricted low cut filter setting.

This paper describes the SSEP patterns in BD when using restricted filter bandpass setting, with special emphasis on the dissociation of some SSEP components when cephalic and non-cephalic references are used. A characteristic SSEP pattern was found: absence of N20 and later responses in the Cc'-Fpz lead and preservation of all or some of the so-called subcortical components in the rest of the derivations. We noted an interesting dissociation in which some SSEP components were not recorded in the scalp-non cephalic derivations, but they were still present in the neck-cephalic and spine channels, with inverse polarity. We selected a restricted bandpass for the scalp-non cephalic, the neck-cephalic and the spine derivations, and we found this dissociation not only for P13-N13 and P14-N14, but for Nm-Pm' and Pm-Nm' components. It is likely that components Nm-Pm' and Pm-Nm' are "far-field potentials" that appear when the slow wave N18 is filtered out by the use of a restricted low filter setting. Our data further suggest that all components after N14-P14, recorded with restricted filter bandpass also recognize two distinct generator sources. Rostral generators are located probably in the brainstem and/or thalamus, but at least a significant part of these SSEP components are generated at the very lower part of the medulla oblongata (dorsal column nuclei) and/or at the upper cervical spine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Somatization, psychiatric disorder, and stress in utilization of ambulatory medical services.

Examined the prediction from Mechanic's (1972) attribution theory of somatization that somatizers who are under stress will overuse ambulatory medical services. Two hundred fourteen volunteer patients from university ambulatory care clinics completed the Diagnostic Interview Schedule and the Life Experiences Inventory. We examined somatization, psychiatric diagnoses, and life stress-and the interaction of these factors-in predicting frequency of medical visits during the preceding year, after controlling for need (active medical problems) and predisposing factors. As hypothesized, life stress interacted with somatization in predicting number of medical visits; somatizers who were under stress made more visits to the clinics than did nonsomatizers or somatizers who were not under stress. Although stress affected somatizers most, stress was predictive of increased medical utilization for all patients. These results suggest that psychological services intended to reduce overutilization of outpatient medical services might best focus on stress reduction and be most beneficial to somatizers.

Adolescent↗
PubMed1991

Psychosomatic symptoms in medical outpatients: an investigation of self-handicapping theory.

Investigated self-handicapping theory as it relates to somatization in medical patients. We predicted that medical outpatients (N = 113) would report psychosomatic symptoms in response to events that threaten their self-esteem. As predicted, results of hierarchical multiple regression indicated that high-perfectionism patients reported somatic symptoms positively related to the number of events that jeopardize their sense of accomplishment, whereas low-perfectionism patients' somatic symptoms were not related to these events (p = .005). Contrary to prediction, high-dependency patients did not differ significantly from low-dependency patients in the relationship of somatic symptoms and events that threatened their interpersonal relationships (p = .115). Implications of these findings and the utility of self-handicapping theory for predicting somatization in medical patients are discussed.

Adult↗
PubMed1990

Depression in medical outpatients. Underrecognition and misdiagnosis.

Depression is a common problem in medical outpatients, yet primary care physicians recognize the disorder in only about half of their depressed patients. We compared physician recognition of depression (defined by chart notation or prescription of antidepressants) with diagnoses generated by the Diagnostic Interview Schedule (DIS) in 265 medical outpatients. Using DIS criteria, diagnoses of major depression in the past year or dysthymia (chronic minor depression) were made in 70 patients. Physicians recognized as depressed only 25 (35.7%) of the 70 DIS-depressed patients. However, 36 patients who were not depressed according to DIS were "recognized" as depressed by physicians. Patients misdiagnosed as depressed by physicians were older, less educated, had more outpatient visits, and were prescribed more medications. Receiver operating characteristic curves of two self-report depression scales suggest that these scales may assist physicians in recognizing depressed outpatients. We conclude that physicians underrecognize and misdiagnose depression in medical outpatients.

Adolescent↗
PubMed1990

Endorsement of dysfunctional beliefs depends on current mood state.

In two studies we tested the hypothesis that endorsement of dysfunctional beliefs depends on current mood state for persons who are vulnerable to depression. The first study showed that reports of dysfunctional beliefs vary with spontaneous diurnal mood fluctuations in 47 depressed psychiatric patients. The effect of mood state was highly significant (p less than .01); dysfunctional thinking increased when mood was worst and decreased when mood was best. The second study conceptually replicated this finding in a population of asymptomatic subjects. As predicted, reports of dysfunctional beliefs varied as a function of mood state in 14 persons who had experienced a depressive episode but not in 27 who had never been depressed. These findings support the cognitive theory of depression, which proposes that dysfunctional beliefs are vulnerability factors for depression but also that reporting of dysfunctional beliefs depends on current mood state.

Adult↗
PubMed1990

The first cases of Helicobacter pylori (Campylobacter pylori) reported from Costa Rica.

Two gastric antrum biopsies of each of 92 consecutive patients undergoing gastroendoscopy were studied. The first biopsy was cultured for Helicobacter (Campylobacter) pylori. The second specimen was fixed and processed for histopathological analysis. The bacteria were isolated from 34 (81%) of 42 patients with nonspecific chronic gastritis, 19 (90%) of 21 cases of duodenal or gastric peptic ulcer, and from 3 (23%) of 13 normal patients. The overall frequency of isolation was 62 (67%) of the 92 cases.

Adult↗
PubMed1987

Further differences between brain-stem auditory potentials evoked by rarefaction and condensation clicks as revealed by vector analysis.

Vectorial analysis of the brain-stem auditory evoked potential (BAEP) elicited by either condensation and rarefaction stimuli was performed in 22 healthy subjects. Besides differences in latency of components III and V ('R' longer than 'C'), a significant difference was found between the directions of the vector calculated over the descending limb of wave III, with an ascending direction for 'C' responses and a contralateral direction for 'R' responses. The possible origins of these differences are discussed. It is concluded that the use of alternating or isolated single polarity clicks is not recommended, mainly when assessing integrity of central auditory pathways.

Acoustic Stimulation↗
PubMed1987

[Not Available].

Explore the source record for details and available documents.

History, Modern 1601-↗
PubMed1987

[An awareness campaign on the diagnosis and prevention of colon and rectal cancer. Planning and evaluation of its results].

Colorectal cancer is very frequent in Argentina. It is the third most frequent cancer, after skin and breast tumor in the city of Rosario. Our population usually ignores the symptoms of colonic cancer and early diagnosis are infrequent. The Societies of Gastroenterology, Oncology and Colonoproctology organizes a public awareness campaign during july, august and september 1985 in Rosario and its surrounding (population 1,300,000) by means of newspaper, radio and specially by television, describing the symptoms were present, as well as insisting of the possibility of prevention by endoscopy diagnosis and removal of polyps. Literature and pamphlets were distributed, and information letters were send to all the physicians in Rosario. An International update meeting on colon and rectal took place. The results of this campaign were evaluated through the Tumor Registry of Rosario. Since september 1984 still february 1986, the monthly incidence of polyps and cancer of the colon and rectum was recorded. The monthly average incidence of polyps was 18.9. Previous to the campaign, the monthly average of diagnosed polyps was 17.5; during the campaign, 27.5; and after it, 13.8. The monthly average of colorectal cancer was 39, before the campaign, 41; during the campaign, 49, and 26 afterwards. These results were statistically studies by the parametric test of Mann and Whitney. During the campaign a significant (p = 0.05) increase of diagnosed polyps and cancers, was found. Our conclusion is that the awareness was successful, but we think that it is necessary to insist with periodic and longer campaigns.

Argentina↗
PubMed1985

Presence of a membrane bound pyroglutamyl amino peptidase degrading thyrotropin releasing hormone in rat brain.

In the present work we studied the pattern of degradation of [3H-Pro]-TRH by soluble and membrane fractions from rat brain. Demonstration of the membrane bound or soluble nature of the activities was obtained by comparing their distribution to that of lactate dehydrogenase and by looking at the effect of NaCl washes on the membrane fractions. We observed that the pyroglutamyl amino peptidase activity detected in brain homogenates is a result of two different enzymes. One of them is a soluble enzyme previously characterized, that needs DTT and EDTA for its expression, is inhibited by SH-blocking agents such as iodoacetamide and utilizes p-glu-beta-naphtylamide as a substrate. The other one, a membrane enzyme, is inhibited by chelating agents such as EDTA and DTT, is not affected by iodoacetamide and does not degrade p-glu-beta-naphtylamide. The later presents some specificity towards TRH as shown by competition experiments with TRH analogs. We were able to corroborate that the post proline cleaving enzyme acting on TRH is a soluble enzyme. In membranes we demonstrated also the presence of a post-proline dipeptidyl aminopeptidase. The membrane bound pyroglutamidase activity is a potential new source of L-his-L-pro-diketopiperazine in brain. The presence of a TRH degrading enzyme in membrane fractions is of particular importance in searching an inactivation mechanism of this peptide once it is released into the synaptic cleft.

Aminopeptidases↗