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A Arregui

Publications and source records attributed to A Arregui.

At least 19 recordsLinked to original sources
PubMed2001

Energetic metabolism in mouse cerebral cortex during chronic hypoxia.

We measured the activities of Na(+)K(+) ATPase and of enzymes of the glycolytic pathway, Krebs cycle, and the respiratory chain in cerebral cortex of mice exposed to chronic hypoxia for three weeks and compared their values with those of sea level controls. There were no differences in Na(+)K(+) ATPase activity or in the activity of glycolytic enzymes. In the Krebs cycle, a 66% increase of succinate dehydrogenase activity was found due to a lower Km. In contrast, respiratory chain cytochrome oxidase activity was reduced by 12% in mice exposed to hypoxia. This suggested that the metabolic demand would be satisfied despite the respiratory chain depression (cytochrome oxidase), probably due to anaerobic energy production within the mitochondria (succinate dehydrogenase).

Animals↗
PubMed1999

Increased brain capillaries in chronic hypoxia.

The effect of chronic hypobaric hypoxia (28 days, 455 Torr) on the organization of brain vessels was studied in Balb/c mice. In comparison to age-matched controls kept at sea level, emulsion-perfused capillaries in hypoxic mice showed marked dilation in all brain areas studied. Capillary length per unit volume of tissue (Lv) was increased in the cerebellar granular layer, the caudate nucleus, the globus pallidus, the substantia nigra, the superior colliculus, and the dentate gyrus. There was a selective increase of Lv in the hippocampus (CA1 strata pyramidale and lacunosum and CA3 strata pyramidale and oriens) and in somatosensory cortex layers V and VI, motor cortex layers II, III, V, and VI, and auditory cortex layers II and III. An increase in capillary surface area per unit volume of tissue was also determined in several brain areas, including layer IV of somatosensory cortex, where Lv was not significantly increased. The O2 diffusion conductance and PO2 in the tissues were estimated with a mathematical model. The remodeling of capillary diameter and length during chronic hypoxia accounts for the significant increase of O2 conductance to neural tissues. Also the estimated tissue PO2 in chronic brain hypoxia is markedly increased in the caudate nucleus and the substantia nigra compared with acute hypoxia. These results suggest that formation of new capillaries is an important mechanism to restore the O2 deficit in chronic brain hypoxia and that local rates of energy utilization may influence angiogenesis in different areas of the brain.

Animals↗
PubMed1998

[Incidence and risk factors in fractures of the proximal femur due to osteoporosis].

Every year more than one million fractures of the proximal femur occur in the world, especially in older persons. Given the continuous aging experienced by populations, such fractures will become more frequent from year to year and will constitute a growing public health problem. The largest increase is expected to occur in countries of Latin America around the year 2050. Since nearly 70% of all atraumatic fractures in persons over 45 are due to osteoporosis, a case-control study was conducted in the city of Mar del Plata, Argentina, for the purpose of investigating the incidence of and the risk factors associated with proximal femur fractures due to osteoporosis. Between 1 August 1992 and 31 July 1993, a record was kept of all fractures of the proximal femur due to osteoporosis in persons over 50 years of age that visited any of the city's 30 public and private health centers. A total of 246 cases was recorded. The incidence rate per 100,000 inhabitants in the above-50 population was 259 among women and 92 among men, for a ratio of 2.8:1. The incidence was consistently higher in the older age groups, especially in persons over 75. Factors associated with a statistically significant increased risk of fracture of the proximal femur were: a history of neurologic disorders, psychotherapeutic drug use, alcohol consumption, previous fractures, cardiovascular disease, and a decreased intake of milk products. There were no observed differences between cases and controls with respect to age at menopause, weight, height, previous activity, smoking habits, or sun exposure, nor were such differences detected in terms of the percentage of women who had undergone oophorectomy.

Aged↗
PubMed1996

Chronic hypoxia induces modification of the N-methyl-D-aspartate receptor in rat brain.

This study examined [3H]MK-801 binding to the N-methyl-D-aspartate (NMDA) receptor in membranes prepared from cerebral cortex, hippocampus and corpus striatum of 3 week old rats exposed to 10 weeks of intermittent hypobaric hypoxia (4300 m; 450 Torr) and compared results with those of normoxic controls. The cortex, hippocampus and striatum of hypoxic animals had a 36, 35 and 31% reduction in binding sites (Bmax) and a 29, 32 and 17% decrease (reflecting increased affinity) in the dissociation constant (Kd) when compared to controls. In the cerebral cortex, both glutamate (100 microM) and glycine (10 microM) enhanced 3[H]MK-801 binding by two to 3-fold. Coagonist glutamate, however, had a higher EC50 (0.44 microM) in the hypoxic cortical membranes when compared to controls (0.28 microM). No significant differences were found in the EC50 of glycine. The results show that the NMDA receptor is altered in several brain regions of rats developing in a hypoxic environment.

Animals↗
PubMed1995

Reduced mitochondrial respiration in mouse cerebral cortex during chronic hypoxia.

Respiratory activity and NADH CoQ reductase (complex I) and cytochrome c oxidase (complex IV) activities were measured in free (non-synaptosomal) mitochondria isolated from cerebral cortex of male Balb/c mice exposed to intermittent hypobaric hypoxia (450 Torr; 4300 m) for 21 days and compared to normoxic (sea level) controls. In the hypoxic we found a 47% reduction of oxygen uptake during state 3 (ADP and substrate present), 12% reduction during state 4 (no ADP present) and 20% reduction in the uncoupled respiration rate with pyruvate plus malate as substrates. Respiratory control ratio (RCR) decreased by 24%. No change in the ADP/O ratio was seen. NADH CoQ reductase activity decreased by 30% and cytochrome c oxidase by 17%, suggesting that under conditions of chronic hypoxia, the reductions of mitochondrial respiratory activities are caused, at least in part, by enzymatic alterations of the electron transport chain (complex I and complex IV). The decreased activity of these enzymes could contribute to alterations in neuronal activity by reducing brain energy metabolism during development under conditions of chronic hypoxia.

Animals↗
PubMed1995

Attitudes and behaviors of African-American and Mexican-American women delivering newborns in inner-city Los Angeles.

To study some of the factors relating to the care of mothers and newborns in an inner-city hospital, three sources of information were reviewed: an obstetric database including information on prenatal care and perinatal mortality, a database of all admissions to the hospital neonatal intensive care unit over the past 5 years, and a detailed questionnaire concerning attitudes and behaviors of recently delivered women. While analyses from these hospital-based data are not conclusive, the results add evidence for the following propositions: 1) Optimal prenatal care is infrequently obtained by mothers delivering at inner-city hospitals. Lack of prenatal care is clearly associated with increased perinatal mortality. While the need for prenatal care is appreciated by 98% of the mothers in this sample, the most frequent reasons why prenatal care is not obtained earlier or more frequently involve knowledge about and access to prenatal care. 2) Inner-city mothers, in general, manifest attitudes and behaviors that promote the welfare of their pregnancies and newborns. These attitudes and behaviors are in stark contrast to those that are frequently attributed to inner-city women by the media. 3) Acute perinatal medical and nursing care are perceived by many postpartum women as suboptimal, particularly in terms of the lack of respect shown to patients by nurses and doctors. 4) Improved acute obstetric and neonatal care improves perinatal morbidity and mortality of infants delivered at inner-city hospitals.

Adult↗
PubMed1994

Autoradiographic evidence for increased dopamine uptake sites in striatum of hypoxic mice.

Ligand binding to dopamine uptake sites, D1 and D2 dopamine receptors was measured autoradiographically in brain sections of mice exposed to intermittent hypobaric hypoxia (450 Torr; 4,300 m) for 14 days and compared to sea level controls. Desipramine-insensitive [3H]mazindol, [3H]SCH23390 and [3H]YM-09151-2 were used respectively for the labeling of the three binding sites. After 14 days, the striatum of hypoxic mice showed a significant 21% increase in dopamine uptake sites, one of the loci of action of cocaine. A similar (28%) but non-significant increase was found in the ventral tegmental area. No changes were seen in the activities of D1 or D2 receptors in several areas examined including the substantia nigra and the striatum.

Animals↗
PubMed1994

Migraine, polycythemia and chronic mountain sickness.

In the epidemiological study among 379 adult men with permanent residence at 4300 meters (14,200 feet), we found 32.2% with migraine (mostly migraine with aura), 15.2% with tension-type headache (episodic more than chronic), and 7.2% with other headaches. The frequency of migraine increased with age from 30.1% in the 20-29 year age group to 36.8% in the 50-59 year group. Episodic tension-type headaches also showed this trend. We found an age-specific increase in the frequency of high hemoglobin (Hb > 213 milligrams), low oxygen saturation (O2 saturation < 81.5%) and high chronic mountain sickness scores. Male migraineurs and those with more than two headaches per month had the highest hemoglobin levels and chronic mountain sickness scores when compared with high altitude men without headaches.

Adult↗
PubMed1994

Chronic mountain sickness and chronic lower respiratory tract disorders.

To determine whether chronic lower respiratory tract disorders contributed to the development of chronic mountain sickness (CMS), we compared hemoglobin (Hb), oxygen saturation (SaO2), peak expiratory flow rate (PEFR), and CMS scores (CMSsco) in 97 normal men at high altitude with those of men at high altitude with acute (ARD; n = 12), chronic upper (CURD; n = 33), and chronic lower (CLRD; n = 34) respiratory diseases. The clinical diagnosis of the different types of respiratory disorders was based on the results of a questionnaire and physical examination performed during an epidemiologic study. The CLRD group had higher CMSsco and Hb concentrations, and lower SaO2 and PEFR values when compared with the other groups. The frequency of low PEFR and SaO2 and high Hb and CMSsco was substantially higher in men with CLRD when compared with normal subjects. The results support the hypothesis that there is an association between signs and symptoms of CMS, as measured by the CMSsco, and CLRD. The chronic hypoxemia, product of chronic lung diseases, would cause excessive erythrocytosis and increase the signs and symptoms of CMS. Studies of Hb, PEFR, pulse oximetry, and CMSsco are recommended for early detection of high-altitude natives at risk of developing CMS.

Adult↗
PubMed1993

Effects of two selective dopaminergic antagonists on ethologically-assessed encounters in male mice.

1. Although it is accepted that dopaminergic antagonists suppress aggressive behaviour, the drugs used have been relatively non-selective or specific to the D2 receptor. 2. The selective D1 antagonist, SCH 23390, makes it possible to evaluate the impact of this receptor on aggressive behaviour. 3. The effects of SCH 23390 and Spiperone (a D2 antagonist) on the aggressive behaviour of mice were assessed employing a "standard opponent" test. 4. Both drugs markedly decreased aggressive behaviour whilst increasing immobility. However, whilst SCH 23390 increased immobility to a small extent, Spiperone, produced a general decline in active behaviours. 5. It appears that the D1 receptor inhibition of aggression is the more specific.

Aggression↗
PubMed1992

Pathophysiology and epidemiology of chronic mountain sickness.

Chronic mountain sickness, which affects permanent residents of high altitudes, is the outcome of a progressive loss of ventilatory rate which naturally occurs with age and resulting in excessive hypoxemia and polycythemia. A theoretical model predicts the progressive failure of homeostatic control of the hemoglobin concentration when the values increase above those found at sea level. This is confirmed by lack of feedback mechanism between high altitude erythrocytosis and serum erythropoietin. The results of epidemiological studies are in agreement with the physiological findings. In a male population living at 4,300 m, an increase with age of the prevalences of excessive erythrocytosis (Hb > 213 g/l), blood oxygen saturation < 83%, headaches and a high score of symptoms of chronic mountain sickness has been found. The studies suggest the possibility that in addition to an accentuated hypoxemia, the excessive erythrocytosis may also result from an overreaction of the bone marrow to a fixed level of hypoxemia in ageing individuals.

Adult↗
PubMed1988

Spastic paraparesis and HTLV-I infection in Peru.

Three of 6 patients with spastic paraparesis in Lima, Peru, were found to have antibodies to human T-lymphotropic virus type I (HTLV-I). Blood and cerebrospinal fluid antibodies were confirmed by Western blot analysis. Multilobulated lymphocytes in blood and cerebrospinal fluid of the index case stained with monoclonal antibodies for T-helper cells and for T10, an activation marker. Blood mononuclear cells from patients with HTLV-I-associated myelopathy showed spontaneous proliferation in culture, evidence of interleukin-2 receptors, and decreased natural killer cell activity.

Adult↗
PubMed1984

Regional distribution of pro-opiomelanocortin-derived peptides in the human brain.

The regional distribution of pro-opiocortin-derived peptides and methionine enkephalin was investigated in human brain post-mortem. Sequence-directed radioimmunoassays for beta-endorphin, gamma-lipotropin, adrenocorticotrophin, corticotrophin-like intermediate lobe peptide (ACTH18-39, CLIP) alpha-MSH and methionine enkephalin were used and 40 different human brain areas were assayed. The regional distribution of all the pro-opiomelanocortin-derived immunoreactivities were correlated with highest amounts of beta-endorphin, gamma-lipotropin and ACTH in the hypothalamus, amygdala, periventricular grey, substantia nigra and superior colliculus. The distribution of beta-endorphin, gamma-lipotropin and ACTH did not parallel the distribution of methionine-enkephalin immunoreactivity which was present in the globus pallidus, nucleus accumbens and substantia nigra. Gel exclusion chromatography (G-50) showed that pro-opiocortin-related peptides in the human hypothalamus and periventricular grey separated in positions consistent with the major immunoreactive forms being beta-endorphin, gamma-lipotropin, ACTH and CLIP.

Adrenocorticotropic Hormone↗
PubMed1983

[Mucolipidosis II or I-cell disease in the neonatal period].

A newborn with the clinical, radiological and biochemical features of mucolipidosis II or "I cell disease" is presented. Some aspects of differential diagnosis in neonatal period and of the outcome are commented. The infant had also a single right kidney and agammaglobulinemia without further alteration of the humoral or cellular immunity at 10 months of age.

Abnormalities, Multiple↗