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Biomedical subjects

N Garcia

Publications and source records attributed to N Garcia.

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

Physiological changes induced by pre-adaptation to high altitude.

To study the physiological effects of pre-adaptation to high altitude, seven subjects were submitted to acclimatization at 4350 m followed by intermittent acclimation in a low barometric pressure chamber (5000 m to 8500 m). The subjects then spent 25 days in the Himalayas. Ventilatory and cardiac responses were studied during a hypobaric poikilocapnic hypoxic test performed both at rest and during exercise (100 W) in normoxia and in hypoxia (barometric pressure: 589 hPa, altitude: 4500 m). Haemoglobin, erythrocytes, reticulocytes, packed cell volume, 2,3-diphosphoglycerate (2,3-DPG) and erythropoietin (EPO) were measured. All variables were studied before pre-adaptation to high altitude (A), after the acclimatization period (B), after the acclimation period (C) and after the expedition (D). The ventilatory and cardiac responses were characterized by an increased tidal volume in hypoxia (+33% during exercise in B, P < 0.05; +100% at rest and +33% during exercise in C, P < 0.05) without any change in respiratory frequency, whereas an increased systolic blood pressure was only observed in C during exercise in hypoxia [+23 mmHg (3.07 kPa), P < 0.01]. Arterial O2 saturation was higher in hypoxia in C and D, both at rest (+8.2% and +4.7%, P < 0.01, respectively), and during exercise (+6.3% and +6.3%, P < 0.01, respectively). Erythrocytes, haemoglobin and packed cell volume did not vary significantly. The number of reticulocytes was higher in B (+172%, P < 0.05) and in C (+249%, P < 0.05). EPO and 2,3-DPG increased only in C (+770%, P < 0.01 and +23%, P < 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1993

Tumor-infiltrating lymphocytes expressing IOT-10 marker. An immunohistochemical study of a series of 185 brain tumors.

The presence of IOT-10-positive lymphocytes among the tumor-infiltrating-lymphocyte (TIL) population was studied in a series of 185 brain tumors. In most of the tumors, IOT-10-positive lymphocytes were identified, but generally they were scarce and masked among the tumor cells, suggesting that NK-cells exercise a poor participation in the tissular response against brain tumors. Isolated tumor cells showing IOT-10-positivity were found in low-grade astrocytomas, neurinomas and medulloblastomas. IOT-10-positivity on both tumor neuropil and tumor cells was considered a characteristic finding in oligodendrogliomas. The number of IOT-10-positive NK-cells in brain metastases and in cerebellar hemangioblastomas was comparatively greater than in other types of brain tumor. Since in brain metastases, the presence of IOT-10-positive NK-cells can be related to the tissular response to an extracerebral malignancy, their considerable presence in cerebellar hemangioblastomas is an enigmatic finding that deserves further attention.

Antigens, Neoplasm↗
PubMed1989

Thyrotropin-releasing hormone (TRH)-Gly conversion to TRH in rat ventral prostate is inhibited by castration and aging.

TRH levels in rat prostate are very high in the 2-month-old rat and decline at least 90% during the next 2 yr. This decline in prostatic TRH levels with aging may be a significant factor in benign prostatic hypertrophy in man and other animals. Because prostatic TRH correlates positively with serum testosterone and negatively with serum thyroid hormone levels, we have examined the possibility that the age-related decline in prostatic TRH is hormonally regulated. TRH and a TRH precursor peptide, TRH-Gly (pGlu-His-Pro-Gly), were measured in ventral prostates from 2-, 5-, and 18-month-old Fisher 344 male rats using a combination of HPLC and specific RIAs for TRH and TRH-Gly. Similar measurements were made in a group of 2-month-old Sprague-Dawley rats which were castrated, sham castrated, or left untreated for 3 or 7 days before death. Aging and castration resulted in a significant decrease in the absolute TRH concentration as well as the TRH/TRH-Gly ratio, but no significant change was observed in TRH-Gly levels. The serum testosterone concentration did not change with aging, but serum T4 levels fell significantly. Because testosterone levels do not change during the first 18 months of life in most rat strains, and hypothyroidism in young animals is associated with a significant increase in prostate TRH and TRH-Gly levels, we conclude that the aging-related decline in prostate TRH biosynthesis is not the result of a hypogonadal state.

Aging↗