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Biomedical subjects

J Alvarez

Publications and source records attributed to J Alvarez.

At least 325 records · Page 18Linked to original sources
PubMed1983

[Localized pulmonary interstitial emphysema. Therapeutic management of 3 cases].

Persistent localized interstitial emphysema (PLIE) is a severe complication of assisted ventilation in the neonatal period. From january 1980 to may 1982, 156 cases of IRDS where treated in our Intensive Care Unit. Three of these patients developed this type of emphysema. The initial management was conservative. In two cases, when high ventilatory pressures, and oxygen concentrations were needed to maintain normal blood gases, lobectomy was performed. In both of them mechanical ventilation could be withdrawn shortly after surgery. The third case was managed with conservative medical therapy, and the patient died. In conclusion, when PLIE is diagnosed and does not resolve with medical therapy, the patient needs increasingly higher oxygen concentrations and ventilatory pressures, or mechanical ventilation can not be withdrawn, lobectomy should be performed as long as the process is well localized.

Humans↗
PubMed1982

Regulation of axonal microtubules: effect of sympathetic hyperactivity elicited by reserpine.

The density of microtubules in sympathetic postganglionic fibres of the cat was studied with the electron-microscope before and after administration of reserpine. The microtubule density was 56 microtubules per square micron under basal conditions. Six hours after reserpine administration, the density rose by 46%. This change was still present 55 h later. At least 31% of the total microtubular protein in the axoplasm of sympathetic fibres of the unrestrained cat was estimated to be in the soluble form. The increase in microtubule density was prevented by a section of the preganglionic fibres. Microtubules of the unmyelinated fibres of the cutaneous sural nerve were unaffected by reserpine treatment. Since reserpine is known to produce hyperactivity of sympathetic nerves, it is concluded that this hyperactivity is instrumental in the increase of the number of axonal microtubules. It is proposed that the electrical activity of nerves regulates axonal microtubules in the living animal.

Animals↗
PubMed1982

[Seasonal variation and diagnostic value of plasmatic levels of 25-hydroxycholecalciferol (author's transl)].

Plasma 25-hydroxycholecalciferol (25OHD3) has been measured by means of gas-liquid chromatography (HPLC) in 23 healthy mothers and their normal full term babies. It was measured as well in twelve infants, nine children of 1.5-5 years and in 57 schoolboys of 5-12 years. Infant population showed a wide variation of plasma 25OHD3 (m +/- SEM) being 16.4 +/- 1.45 ng./ml. Children 1.5-5 years old showed 12.7 +/- 2.3 ng./ml. which is lower than expected. Schoolboys showed a normal values of 22.9 +/- 1.3 ng./ml. These differences are believed to be due to a great sunshine exposition. In perinatal group, births taking place in winter showed a very low level of 25OHD3 (m +/- SEM) in mothers (6.9 +/- 1.8 ng./ml.) and consequently in their newborns (5.3 +/- 1.6 ng./ml.). Those taking place in summer showed significantly higher figures for both mothers (18.9 +/- 2.7 ng./ml.) and newborns (12.9 +/- 2.4 ng./ml.). A good correlation (r = 0.83) between plasma levels of mothers and newborns is found.

Adolescent↗
PubMed1981

Removal of PHA from supernatants containing T-cell growth factor.

Supernatants of human PBL cultures stimulated with PHA contain a lymphokine named T-cell growth factor (TCGF). To remove the contaminant PHA from these supernatants, we have designed a simple and effective method based on the binding properties of this lectin to chicken red blood cells. This procedure completely removes the functional activities of a PHA solution, both in lectin-induced cellular cytotoxicity against erythroid targets and in DNA synthesis of fresh PBL. The TCGF activity remaining in the supernatants after absorption with CRBC is dependent on the cellular concentration employed in the preparation of the supernatants. The absorption procedure does not remove significant TCGF activity in the supernatants prepared at high cellular concentrations (5 X 10(6) cells/ml), whereas in those prepared at low cellular concentrations (1 X 10(6) cells/ml) a partial loss of TCGF activity is detected.

Animals↗
PubMed1981

Enhancement of the functional activities of human T cells after their interaction with SRBC.

We have examined the functional consequences of the exposure of human lymphocytes to sheep red blood cells (SRBC). Peripheral blood lymphocytes (PBL) were incubated wih SRBC under optimal conditions for their interaction and, after lysis of the erythrocytes, the unfractionated PBL were examined for several T cell functions. Only after exposure to SRBC, but not after incubation with mouse, ox, chicken, or human erythrocytes, the unfractionated PBL showed an increased reactivity in the following functions: 1) Production of T cell growth factor, after PHA stimulation; 2) mitogenic response to suboptimal doses of PHA and Con A, and 3) response in mixed lymphocyte culture. Other functional activities, such as natural cytotoxicity (NK) and antibody-dependent cellular cytotoxicity (ADCC) were also enhanced by the interaction of PBL with SRBC, but the increases in cytotoxic activities were not consistently detected. Taken together, these results indicate that the interaction of PBL with SRBC has functional consequences in the reactivity of T cells producing an enhancement of several in vitro T cell functions.

Animals↗
PubMed1981

Effects of hydrocortisone sodium succinate on the electrophysiological properties of hypoxic rabbit papillary muscle.

Hydrocortisone sodium succinate (HSS) (50 mg/1) was tested as a protective agent against the effects of hypoxia on rabbit papillary muscle fibres. No effect of HSS was observed on the electrophysiological variables studied in aerobic condition. Hypoxia (65-75 mmHg, 8.66-10.0 kPa) had no effects on the resting potential, amplitude and overshoot, and shortened the action potential at 0 and -60 mV levels of repolarization. In the presence of HSS the resting potential, amplitude and overshoot were also unaffected by the hypoxic condition. However, when measured at -60 mV level the changes on the repolarization phase after 15 and 60 minutes of hypoxia were significantly reduced, 14% and 24% respectively (p less than 0.001) as compared with the values obtained in the series without HSS.

Action Potentials↗
PubMed1981

Changes in electrical and mechanical activities of rabbit papillary muscle during hypoxic perfusion.

The influence of moderate hypoxia (p02 : 70 mmHg) on action potential and contraction of isolated rabbit papillary muscles was analyzed. 1. Action potential duration, maximum twitch tension and time-to-peak tension decreased during 60 min of hypoxic perfusion, while resting tension increased and resting potential, overshoot and fast depolarization of the action potential remained constant. 2. MnCl2 (5 mM), after 60 min of hypoxia, abolished overshoot increased resting potential, and further reduced action potential duration. "Slow"action potentials induced by isoproterenol (2.5 X 10(-6) M) in KCl (20 mM) depolarized muscles, were highly resistant to hypoxic perfusion. This resistance indicates that the inflow of cations through slow channels persists under these hypoxic conditions. 3. CsCl (2-4 mM) increased action potential duration in hypoxic fibers to control (O2) values. These results suggest that an increase in membrane background K conductance could account for the reduction in action potential duration under hypoxic incubation. A possible relationship between changes in internal free calcium concentration and background K conductance during hypoxia is considered.

Action Potentials↗