Biomedical subjects

R M Ramírez

Publications and source records attributed to R M Ramírez.

5 recordsLinked to original sources

PubMed1999

RPD3 (REC3) mutations affect mitotic recombination in Saccharomyces cerevisiae.

Prior research identified the recessive rec3-1ts mutation in Saccharomyces cerevisiae which, in homozygous diploid cells, confers a conditional phenotype resulting in reduced levels of spontaneous mitotic recombination and loss of sporulation at the restrictive temperature of 36 degrees C. We found that a 3.4-kb genomic fragment that complements the rec3-1ts/rec3-1ts mutation and which maps to chromosome XIV, is identical to RPD3, a gene encoding a histone de-acetylase. Sporulation is reduced in homozygous diploid strains containing the rec3-1ts allele at 24 degrees C, suggesting that this allele of RPD3 encodes a gene product with a reduced function. Sporulation is abolished in diploid strains homozygous for the rpd3Delta or rec3-1ts alleles, as well as in rpd3Delta/rec3-1ts heteroallelic diploids, at the non-permissive temperature. Acid-phosphatase expression has been shown to be RPD3 dependent. We found that acid-phosphatase activity is greater in diploid strains homozygous for the temperature-sensitive rec3-1ts allele than in RPD3/RPD3 strains and increased further when mutant strains are grown at 36 degrees C. We also tested the rpd3Delta/rpd3Delta strains for their effects on spontaneous mitotic recombination. By assaying a variety of intra- and inter-genic recombination events distributed over three chromosomes, we found that in the majority of cases spontaneous mitotic recombination was reduced in diploid rpd3Delta/rpd3Delta cells (relative to a RPD3/RPD3 control). Finally, although 90% of mitotic recombinant events are initiated in the G1 phase of the growth cycle (i.e., before DNA synthesis) we show that RPD3 is not regulated in a cell-cycle-dependent manner. These data suggest that mitotic recombination, in addition to gene expression, is affected by changes in chromatin architecture mediated by RPD3.

Acid Phosphatase↗

PubMedDate not supplied

The immunopathology of human Schistosomiasis-III. Immunoglobulin isotype profiles and response to praziquantel.

Immunoglobulin (Ig) isotype (IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgD and IgE) levels were investigated, both pre- and post-treatment with praziquantel (PZQ), in 43 adults and children chronically infected with Schistosoma mansoni, by means of a two-site, isotype-specific immunoenzymometric assay. The patients were classified as responders (R) or non-responders (NR) on the basis of their circumoval precipitin test (COPT) results 12 months after treatment. In comparison with controls, pre-treatment R children showed significantly higher levels of IgG, IgG1, IgG4 (p < 0.001) and IgE (p < 0.01); and diminished IgG2 (p < 0.05), while NR children showed significantly elevated levels only of IgE (p < 0.05). Twelve months after therapy, R children maintained significantly lower levels of IgG2, but showed significantly decreased levels of IgG, IgG1, IgG4, and IgE, while the Ig isotype profile of NR children was unaltered. Adult R and NR showed similar isotype profiles before chemotherapy, with the exception of significantly elevated IgM levels in R. Twelve months after therapy, R adults showed significantly decreased levels of IgG, IgG1, and IgG4, while NR adults showed only diminished IgG4 levels. These results reveal different Ig isotype profiles in untreated adults and children chronically infected with S. mansoni. The results further show that the pre-treatment Ig isotype profile may be significantly modified after an effective R to chemotherapy, accounted for by down regulation of the IgG1 isotype in association with negative seroconversion of the COPT in R patients. The COPT reaction has been associated with the highly specific egg glycoprotein antigen omega 1, which shows a significant reduction in reactivity six months after treatment. IgG1 may thus play a main role in the response against the omega 1 antigen.

Adolescent↗

PubMedDate not supplied

[Intelligence, memory and malingering: correlation between scales].

OBJECTIVES: To validate the test of memory malingering (TOMM), and to study the influence of intelligence and memory on its performance in brain injury patients. PATIENTS AND METHODS: A total of 30 patients with traumatic head injury were included in the study. All patients were assessed with the Complutense verbal learning test, the Visual Reproduction subtest of the Wechsler memory scale-revised, the Boston naming test, two fluency tests (FAS, and animals), the Wechsler adult intelligence test-III, and with the TOMM. Cognitive results below 1 standard deviation (SD) from normative data were considered 'abnormal'. A parametric correlation between TOMM scores and cognitive tests was used to detect whether memory and intelligence were affecting TOMM performance. Statistical significance was set up at p<0.05. RESULTS: Between 46.1% (Boston) and 81.4% (WAIS-III performance IQ) of the sample presented cognitive deficits. Up to 83.3% of the patients scored above the cutoff point suggestive of malingering in the TOMM (45/50). Significance correlations were found between TOMM scores and memory or intelligence indexes. DISCUSSION: The TOMM is a useful tool to detect malingering in head injured patients. Effects of low intelligence coefficients, as well as memory deficits should be considered in clinical practice when evaluating patients with TOMM scores suggestive of malingering.

Adolescent↗

PubMedDate not supplied

[Anoxic encephalopathy. Clinical description, prognosis and neuroimaging].

OBJECTIVES: To describe the clinical profile (neuropsychological, psychopathological, functional and neuroimaging), as well as the evolution of patients with anoxic encephalopathy. PATIENTS AND METHODS: Nine patients with anoxic encephalopathy attending our Service were included in the study. All patients were assessed with a broad range of neuropsychological tests, checklists of psychopathological symptoms, and several functional scales. A CT/MRI or a positron emission tomography (PET) were performed in five patients. Five patients were admitted to a multidisciplinary rehabilitation program. RESULTS: All patients showed problems in orientation, executive functions, verbal learning an immediate and long-term verbal memory, in association with diffuse cognitive changes in other functions. Psychopathologically, all patients showed apathy-indifference, and eight subjects showed anosognosia. All subjects have an important dependence in daily activities. CT/MRI were normal or showed subcortical changes whereas the PET showed a predominantly cortical hypometabolism with specific patterns. There were no significant improvements after rehabilitation in treated patients. CONCLUSION: In the absence of a unique clinical profile, our patients with anoxic encephalopathy showed similarities in their symptoms (diffuse cognitive deficits with predominance of amnesic and executive impairments; presence of apathy and anosognosia; complete functional dependence; and poor response to the rehabilitation). Functional neuroimaging could be a useful tool for a better understanding of these encephalopathies.

Adolescent↗

PubMedDate not supplied

[Intelligence and prognosis in severe traumatic brain injury: a neuropsychological study with the Wechsler adult intelligence scale (WAIS-III)].

OBJECTIVE: To evaluate the utility of the Wechsler adult intelligence scale III (WAIS-III) as a measure of intelligence after severe brain injury, and to elucidate prognostic factors associated with intelligence coefficients (IQs). METHODS: Forty-six patients (age: 27.4 +/- 12.8 years) attending our service after a severe head injury were included in our study (chronicity: 315.3 +/- 330 days after injury). All patients were assessed with the WAIS-III. WAIS-III IQs were correlated (Pearson and Spearman) with clinical and demographic data. A significance level of p < 0.05 was used in all comparisons. IQs between 1 and 2 standard deviation (SD) below normative data were considered "mild abnormal" while indexes below 2 SD were considered "abnormal". RESULTS: Only eleven patients (25 %) showed normal total IQ with predominance of manipulative (77.7 %) compared to verbal (64.5 %) impairment. Thirty-eight patients (95 %) had difficulties in speed processing, thirty-six (85.6 %) had problems with working-memory, twenty-five (62.5 %) showed impairments in perceptual organization, and twenty-six (62 %) had verbal comprehension deficits. WAIS-III IQs showed significant correlations with length of coma and posttraumatic amnesia duration (p < 0.05). CONCLUSIONS: The WAIS-III is a valid and sensible tool to detect cognitive deficits associated with brain injury. Almost all patients with severe brain injury show abnormal IQs with a slow processing speed as predominant symptom. Length of coma and posttraumatic amnesia seems to be the most relevant parameter related to intelligence in severe brain-injured patients.

Adolescent↗