Biomedical subjects

G Menéndez

Publications and source records attributed to G Menéndez.

3 recordsLinked to original sources

PubMed2002

[Virtual gastroscopy. Preliminary experience].

OBJECTIVE: To define the role of virtual gastroscopy (VG) in the detection of elevated lesions comparing its results with conventional endoscopy (CE) as the gold standard method. MATERIALS AND METHODS: Between December 2000 and July 2001, 19 patients were evaluated. The age ranged between 41 and 72 (mean 58.8 years old). VG and CE were performed in all the patients during the same week. VG were carried out with a multislice CT scanner (Mx 8000, Marconi Medical Systems). The technical parameters used were 3 mm with slices and 1.5 mm reconstruction intervals. The acquisition time was 22 seconds. Images were sent to a workstation (MxView, Marconi Medical Systems) where they were reprocessed in three different ways: 1) Bidimensionally 2) Tridimensionally 3) Virtual Endoscopy Findings of VG were compared with CE. RESULTS: VG detected 39 lesions, whereas CE detected 40 lesions. There were 39 true-positive findings, 2 true-negative findings, 0 false-positive findings and 1 false-negative findings. The Sensitivity (Se) was 97.5%; Specificity (Sp) was 100%, positive predictive value 100% and Negative predictive value 66%. CONCLUSIONS: VG is a new non-invasive method with high Se and Sp in the detection of elevated lesions. The actual role of VG consist in identification of gastric lesions and possibility to diagnose gastric disease.

Adult↗

PubMed2001

Porphyric enzymes in hamster Harderian gland, a model of damage by porphyrins and their precursors. A chronobiological study on the role of sex differences.

The Syrian hamster Harderian gland (HG), representing a highly porphyrogenic organ, was used as a model system for studying physiologically occurring damage of biomolecules by porphyrins and their precursors, phenomena associated with from the pathological situation of porphyrias. The species used exhibits the peculiarity of much higher porphyrogenesis in females than in males, offering possibilities for comparison of effects by different porphyrin levels in one species. Since concentrations of free, and therefore, radical-generating porphyric metabolites are difficult to determine in the presence of high amounts of secreted and crystallizing porphyrins, which are, moreover, mainly surface-reactive, and since indications existed for temporal changes in the oxidative stress caused by these molecules, the following approach was chosen: in HGs of both females and males, activities of the relevant porphyric enzymes, delta-aminolevulinate synthase (ALA-S), delta-aminolevulinate dehydratase (ALA-D) and porphobilinogen deaminase (PBG-D), were determined throughout the circadian cycle. Results were compared with the temporal patterns of lipid peroxidation and protein damage in the same glands. In females, a strong correspondence was observed between protein carbonyl and lipid peroxidation, peaking at the end of both photophase and scotophase; maximal activities of the three porphyric enzymes ALA-S, ALA-D, and PBG-D either coincided or slightly preceded the peaks of oxidative damage. In males, lower enzyme activities, especially in PBG-D, were associated with weakly expressed rhythmicity. Correspondingly, lipid peroxidation was lower and exhibited a smaller rhythm amplitude; protein carbonyl of males showed a temporal pattern differing from that of females, with regard to amplitude and phasing. These data are in agreement with morphological observations demonstrating particularly severe cell damage in the female HG under normal conditions.

5-Aminolevulinate Synthetase↗

PubMed2001

Physiological oxidative stress model: Syrian hamster Harderian gland-sex differences in antioxidant enzymes.

The Syrian hamster Harderian gland, a juxtaorbital organ exhibiting marked gender-associated differences in contents of porphyrins and melatonin, was used as a model system for comparing strong (in females) and moderate (in males) physiological oxidative stress. Histological differences showing much higher cell damage in females were studied in conjunction with lipid peroxidation and activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Lipid peroxidation and enzyme activities were measured throughout the circadian cycle, revealing the importance of dynamical processes in oxidative stress. Especially in lipid peroxidation and in catalase, short-lasting rises exhibited strongest gender differences. Peaks of lipid peroxidation were about three times higher in females, compared to males. Catalase peaks of females exceeded those in males by several hundred-fold. Average levels of superoxide dismutase and glutathione peroxidase were about three or two times higher in females, respectively. A clear-cut diurnally peaking rhythm was found in glutathione peroxidase of females, which was not apparent in males. Glutathione reductase showed differences in time patterns, but less in average activities. The time courses of lipid peroxidation and of protective enzymes are not explained by circulating melatonin, whereas melatonin formed in the Harderian gland should contribute to differences in average levels. Neither damage nor antioxidative defense simply reflect the illumination cycle and are, therefore, not only a consequence of photoreactions.

Animals↗