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Biomedical subjects

M A Paz

Publications and source records attributed to M A Paz.

59 records · Page 4Linked to original sources
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Collagen synthesized and modified by aging fibroblasts in culture.

Collagen is produced by WI-38 diploid human fibroblast cultures throughout their life cycle. It is examined by a sensitive method based on the analysis of specific peptides obtained after digestion with bacterial collagenase. The production and hydroxylation of the collagen is strongly dependent upon the age (population doublings) of the culture and the presence of ascorbic acid. Young cultures (passage 26) produce large amounts of collagen in the absence of ascorbic acid, and this collagen is about 50% hydroxylated compared to that produced by young cultures in the presence of ascorbic acid. Ascorbic acid reduces to about one-half the amount of collagen produced by these young cultures. The young confluent cultures also depend strongly on ascorbic acid for hydroxylation of proline. The dependence declines rapidly with the age of the culture. The collagen produced by young cultures supplied with ascorbic acid is very similar to the type I collagen produced by normal individuals and has about the same degree of hydroxylation of its prolyl residues. The amount of collagen produced by "older" cultures is unaffected by ascorbic acid, but the degree of hydroxylation is normal only if ascorbic acid is present, and is decreased to about 60 to 70% in the absence of the vitamin. "Senescent" cultures showed little, if any, dependency on ascorbic acid, and the collagen produced, with and without the vitamine, is about 80% hydroxylated. The prolyl hydroxylation system of the WI-38 cells and the various controls on the system are age-dependent.

Ascorbic Acid↗
PubMedDate not supplied

Non-invasive pressure support ventilation versus conventional oxygen therapy in acute cardiogenic pulmonary oedema: a randomised trial.

BACKGROUND: Non-invasive pressure support ventilation (NIPSV) is an effective treatment for acute respiratory failure in patients with chronic obstructive pulmonary disease. We assessed the efficacy of this therapy in acute cardiogenic pulmonary oedema in a randomised comparison with conventional oxygen therapy. METHODS: 40 patients were randomly assigned conventional oxygen therapy or NIPSV supplied by a standard ventilator through a face mask, with adjustment of tidal volume and pressure support in addition to a positive end-expiratory pressure of 5 cm water. Physiological measurements were obtained in the first 2 h and at 3 h, 4 h, and 10 h. The main endpoints were intubation rate and resolution time. Analyses were by intention to treat. FINDINGS: Three patients were withdrawn on the basis of clinical and chest radiography results. Endotracheal intubation was required in one (5%) of 19 patients assigned NIPSV and in six (33%) of 18 assigned conventional oxygen therapy (p=0.037). Resolution time (defined as a clinical improvement with oxygen saturation of 96% or more and respiratory rate less than 30 breaths/min) was significantly shorter in the NIPSV group (median 30 [IQR 15-53] vs 105 [50-230] min, p=0.002). NIPSV led to a rapid improvement in oxygenation in the first 2 h. There were no differences in hospital length of stay or mortality. INTERPRETATION: In this study of acute cardiogenic pulmonary oedema, NIPSV was superior to conventional oxygen therapy. Further studies should compare NIPSV with continuous positive airway pressure.

Aged↗