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Biomedical subjects

M Villa

Publications and source records attributed to M Villa.

At least 127 records · Page 7Linked to original sources
PubMed1978

Preparation and purification of estriol, estradiol, and progesterone labeled with radioactive iodine.

Steroids labeled with radioactive isotopes are useful tracers for radio-immunoassay and for in vivo nuclear medecine purposes. We here report and discuss methods for direct labeling of the steroids estriol, estradiol, and progesterone with radioiodine-125 or -131. The purification procedure and some chemical and physical properties of the purified labeled materials are referred to and discussed.

Chloramines↗
PubMed1975

[Value of calcium gluconate labelled with 99mTc in the detection of intracranial tumors].

In a preliminary communication, the authors compare the success coefficients of pertechnate 99m-Tc and of a new labelled molecule: calcium gluconate 99m-Tc, in a group of 32 patients. The results obtained showed the undoubted superiority of the gluconate in comparison with the pertechnate in the detection of intracranial metestases, and in particular those of the posterior fossa. It proved equally effective as bleomycin labeled with 57-Co. Amongst the other types of tumour studies, the use of the gluconate seems to be particularly indicated for neoplasms of the posterior fossa and in those close to the base of the skull and venous sinuses, given the marked reduction in "background noise" obtained when this method is used.

Bleomycin↗
PubMedDate not supplied

Recovery of muscular energy status in chronic alcoholics after 2 weeks of abstinence.

Repeated and excessive consumption of alcohol leads to pathophysiological disorders in skeletal muscles. A successful management of this syndrome requires a strict abstinence and a nutritionally adequate diet. We propose here a simple and noninvasive investigation using 31P magnetic resonance spectroscopy (MRS) to monitor the recovery of the basal energy status of eminence thenar muscles from documented chronic alcoholic patients during a controlled 15-day period of abstinence. Cessation of alcohol abuse induced a significant recovery of the PCr/(PCr+P(i)) ratio otherwise depressed before the abstinence. On the contrary, the relative level of free inorganic phosphate decreased, whereas intracellular pH was not affected. These results demonstrate (a) the rapid improvement of basal muscular energy metabolism during abstinence for patients with a chronic and heavy alcohol consumption, and (b) the feasibility of a follow-up of this recovery by serial examinations using 31P MRS.

Adult↗
PubMedDate not supplied

Low-level measurements of tritium in water.

Using a liquid scintillation counter, an experimental procedure for measuring low-level activity concentrations of tritium in environmental water has been developed by our laboratory, using the electrolytic tritium enrichment. Additionally, some quality tests were applied in order to assure the goodness of the method. Well-known water samples collected in the Tagus River (West of Spain) and the Danube River (Bulgaria), both affected by nuclear plant releases, were analysed and results were compared to previous data. The analytical procedure was applied to drinking water samples from the public water supply of Seville and mineral waters from different springs in Spain in order to characterize its origin. Due to the very low levels of tritium in the analysed samples, some results were reported as lower than the minimum detectable activity concentration (MDA). However, the count rate of these measurements was over the background count rate of LS counter in all the cases. For that reason, an exhaustive discussion about the meaning of the MDA, using an experimental essay, was made in order to establish a rigorous criterion that leads to a reliable value in the case of low-level measurements.

Industrial Waste↗
PubMedDate not supplied

Field study of subjective assessment of negative pressure half-masks. Influence of the work conditions on comfort and efficiency.

The aim of this study was to assess the effects of work conditions on the acceptability and efficiency of respiratory protective devices (RPD). The subjective evaluation of comfort, protection, respiratory and visual constraint, and the acceptable duration of wear of six RPDs against dust was achieved by 30 workers during their actual work. Metabolic rate was evaluated for each worker, and dry and wet air temperatures measured in the work area. RPDs objective protection factor was measured during each of the 180 test periods. In the conditions of this study, the acceptable duration of wear was about 1 h. This duration and the comfort parameters were reduced when the air temperature increased. The younger workers and/or smokers were less sensitive to mask discomfort. Objective protection factors of the RPDs are reduced under warmer conditions, and when the metabolic rate is low. Finally, the results of this study also show the poor capacity of standardized leakage tests to assess the objective respiratory protection of workers in the field. Some hypotheses which can explain this fact are discussed.

Adult↗
PubMedDate not supplied

Methylation pattern of the HLA-DR alpha gene in human tissues.

The CCGG and GCGC sites of the human HLA-DR alpha gene are hypermethylated in human tissues (including B-lymphocytes, T-lymphocytes, muscle, brain, sperm, skin, kidney, suprarenal and mammary glands) and three B-lymphoid cell lines. Therefore, the HLA-DR alpha gene can be transcribed even though extensively methylated. The only exception to the hypermethylated state of the HLA-DR alpha gene is represented by one or both of the two HhaI sites (H1 and H2) localized in the 5' portion of the gene. Analysis of the computer-generated secondary structure of the HLA-DR alpha mRNA suggests that the H1 and H2 sites belong to a region (5'-GAGCGCCCA-3'/5'-UGAGCGCUC-3') exhibiting extensive base pairing. Therefore, unmethylation of these CG sites can contribute in preventing mCG----TG/CA changes in this region, which would lead to extensive alterations of the secondary structure of the 5' portion of the HLA-DR alpha MRNA. On the other hand, the selective pressure to maintain unaltered the methylated CG dinucleotides in the coding regions of the HLA-DR alpha gene could be due to codon restrictions, since the majority of the methylation-related CG----TG or CG----CA variations would generate aminoacid changes. Accordingly, the analysis of different HLA-DR alpha genomic sequences indicates that variations of the CpG dinucleotides occur only in the non-coding portions of the HLA-DR alpha gene.

Base Sequence↗
PubMedDate not supplied

Association between changes in adrenal secretion and cerebral morphometric correlates in normal aging and senile dementia.

The circadian organization of adrenal secretion was studied in 23 healthy elderly subjects, 23 elderly demented patients and 10 healthy young subjects, in order to investigate the relationships between the hypothalamic-pituitary-adrenal axis and some cerebral morphometric parameters. The cerebral morphometric analysis was performed in some subjects of the three groups by MRI. A significant increase in cortisol levels during evening and nighttime was found in both groups of the aged subjects. In elderly subjects, particularly if demented, the mean serum dehydroepiandrosterone sulfate (DHEAs) levels throughout the 24-hour cycle were significantly lower than in young controls. A significant reduction of the hippocampal and temporal volume and an enlargement of the lateral ventricles were found in aged subjects, these changes being significantly related to subjects' age. Moreover, the hippocampal volume was positively correlated with the circadian mesor of DHEAs (i.e., the circadian rhythm adjusted mean) and with the cortisol nocturnal increase. Our data may suggest the existence of a link between the selective impairment of cortisol secretion and DHEAs levels, and the progression of hippocampal degeneration.

Adrenal Glands↗
PubMedDate not supplied

CNS sequelae in Langerhans cell histiocytosis: progressive spinocerebellar degeneration as a late manifestation of the disease.

Central nervous system involvement in Langerhans cell histiocytosis (LCH), formerly known as histiocytosis X, is manifested mainly by diabetes insipidus reflecting local infiltration of Langerhans cells into the posterior pituitary or hypothalamus. We describe two patients with progressive spinocerebellar degeneration appearing 4 and 6 years after the initial diagnosis of LCH. No correlation was found between the clinical course of the disease or its treatment and the neurological impairment. An extensive search for metabolic, toxic, neoplastic, and hereditary etiologies for progressive cerebellar degeneration was negative.

Adolescent↗