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Biomedical subjects

P Ponce

Publications and source records attributed to P Ponce.

34 records · Page 2Linked to original sources
PubMed1980

Connective tissue biomatrix: its isolation and utilization for long-term cultures of normal rat hepatocytes.

A new procedure is introduced for the isolation of connective tissue fibers, called biomatrix, containing a significant portion of the extracellular matrix (basement membrane components and components of the ground substance). Biomatrix isolated from normal rat liver contains >90% of the tissue's collagens and all of the known collagen types, including types I and III and basement membrane collagens. The purified collagenous fibers are associated with noncollagenous acidic proteins (including fibronectins and possibly small amounts of glycosaminoglycans). Procedures are also described for preparing tissue culture substrates with these fibers by either smearing tissue culture dishes with frozen sections or by shredding the biomatrix into small fibrils with a homogenizer. The biomatrix as a substrate has a remarkable ability to sustain normal rat hepatocytes long-term in culture. The hepatocytes, which on tissue culture plastic or on type I collagen gels do not survive more than a few weeks, have been maintained for more than 5 mo in vitro when cultured on biomatrix. These cells cultured on rat liver biomatrix show increased attachment and survival efficiencies, long-term survival (months) and retention of some hepatocyte-specific functions.

Animals↗
PubMedDate not supplied

A noncollagenous matrix for attachment of rat hepatocytes in culture.

Adult rat hepatocytes efficiently attach to intact connective tissue fibers prepared from normal rat liver; this material has been given the name of "biomatrix". The cells remain alive and differentiated for at least 4 months in culture. The liver biomatrix contains both collagen and noncollagenous glycoproteins. Heretofore, the functions of the different components of the biomatrix in facilitating cell adhesion and promoting survival and differentiation of rat hepatocytes have not been investigated. We now report on an aggregate of glycoproteins which were with dilute acetic acid from liver biomatrix and which facilitate hepatocyte adhesion to plastic dishes and collagen. One protein in the extract, with a molecular weight larger than 300,000, was selectively immunoprecipitated with an antibody prepared against the extract and immunoadsorbed to glutaraldehyde-cross-linked rat serum. The antibody did not cross-react with cold-insoluble globulin and selectively inhibited cell attachment. The protein of the molecular weight of 300,000 appears to be specific for liver, since similar extracts prepared from rat lung, kidney, and heart biomatrices did not cross-react with the antibody. Furthermore, the latter extracts did not facilitate cell attachment above values obtained with plain culture dishes. The results suggest that glycoproteins in the biomatrix, which are antigenically distinct from fibronectin, can mediate attachment of rat hepatocytes to plastic dishes and collagen.

Animals↗
PubMedDate not supplied

[Two-years experience with the use of radial artery in coronary revascularization surgery].

INTRODUCTION: Among several other factors, in coronary surgery the results depend on the quality and durability of the grafts. Revascularization employing arterial conduits, namely the radial artery, has been playing a growing role, with the aim of replacing the autologous saphenous vein. The benefits and risks of this strategy is still a matter of controversy. The goal of the present study was the evaluation of the incidence of early complications related to the use of radial artery in the revascularization surgery of the myocardium. METHODS: A series of consecutive patients who underwent coronary revascularization surgery in the CHVNGaia using radial artery, from January 2000 to December 2001, was retrospectively analyzed. Data were obtained through the revision of the clinical charts and hospital database. The major end-point assessed was the 30-day or intra hospital postoperative death; furthermore, acute myocardial infarction, stroke, renal failure, prolonged ventilation and reoperations for acute graft occlusion, bleeding and mediastistinitis were also evaluated. RESULTS: During that period of time, 656 patients underwent coronary revascularization surgery, but the radial artery was used in only 230 (35%). Mean age was 60.2+/- 9.1 years and 42 (18.3%) were female. Two hundred and four patients (88.6%) were operated on under extracorporeal circulation. The average number of grafts was 2.6+/- 0.6 per patient. Mean duration of orotraqueal intubation was 2.4 +/- 6 hours. Thirty patients (14,3 %) developed atrial fibrillation and ten (4.3%) had postoperative bleeding. Perioperative myocardial infarction occurred in five cases (2.2%). Two patients (0.8%) underwent reoperation for mediastinitis and one patient (0.4%) was reoperated on for acute occlusion of the graft. The overall postoperative mortality was 1.3% (3 patients). CONCLUSION: The use of radial artery in coronary revascularization did not caused morbidity and mortality, out of the usual context of coronary surgery. The results of our experience suggest that radial artery can be successfully used in myocardial revascularization surgery, enlarging the possibilities of utilization of arterial autografts.

Female↗
PubMedDate not supplied

[Idiopathic edema, tubular metabolism of water and sodium].

PURPOSE: To look for intrinsic changes in renal tubular water and sodium metabolism in idiopathic edema (IE), independent of the underlying hormonal and vascular defects. DESIGN: Prospective controlled study in patients with edema referred to a nephrology clinic. PATIENTS: Ten female patients with IE were compared with a control group of 4 healthy women. MEASUREMENTS AND RESULTS: Patients and controls were submitted to a base-line test of water loading and lithium clearances, after 12 hours supine position, to study renal tubular handling of Na and H2O in different nephron sites and 5 h water excretion capacity. Patients were then randomized in 2 groups, both receiving standard treatment during 2 months (low-salt diet--70 to 90 mEq of Na per day, stopping diuretics and laxatives, elastic stockings). Group B received in addition carbidopa/levodopa 25/100--3 tabs/day and captopril 6.25 mg q 8 h. At the end of this 2 months period the base-line tests were repeated. We registered a good clinical response, with an average a.m. weight reduction of 2.8 kg and a decrement of the a.m. to p.m. weight gradient from 2.42 +/- 0.3 kg pre-treatment to 0.6 +/- 0.1 kg afterwards. From the several measurements obtained, only global FENa and Proximal Fraccional Reabsorption of Na were significantly different between patients and controls (0.87 +/- 0.09% vs 2.1 +/- 0.2%, p less than 0.001 and 77.4 +/- 2.9% vs 64.0 +/- 3.5%, p = 0.02 respectively), with no difference in distal Na and H2O reabsorption or water excretion capacity. Two months treatment only partially corrected global FENa, and there were no differences in the clinical and physiological effects between the 2 therapeutic groups. CONCLUSIONS: 1--In the absence of orthostatism, H2O and Na metabolism is similar between IE patients and healthy controls, only with an increased selective proximal Na reabsorption in patients. 2--Standard non-pharmacologic therapy was a clinical success, but didn't correct the physiological defect of excessive proximal sodium reabsorption. Treatment results were not improved by pharmacologic intervention.

Adult↗
PubMedDate not supplied

[Hydro-electrolyte changes induced by transurethral prostatic resection].

Transurethral resection prostatectomy (TURP) has been associated with severe hyponatremia due to massive absorption of bladder irrigation fluid (IF). TURP was performed in 41 patients using Sorbitol-Mannitol IF (Group A) and in 6 patients using distilled water (Group B). Six other patients were operated upon using surgical procedures identical in time and type of anesthesia to TURP (Group C). The three groups were studied with the same protocol that included blood collected before (time I), immediately after (time II) the procedure and 1 hour later (time III). Serum sodium decreased significantly in the 3 groups from time I to time II, an average of 3.4 mEq/l with Mannitol-Sorbitol, 2.3 mEq/l with distilled water, and 4.4 mEq/l in group C. Osmolality did not change significantly between the 3 times of collection and Osmolar Gap only increased from time I to II in the Sorbitol-Mannitol group. In conclusion, mild decrements in serum sodium with no clinical relevance are a common post-TURP finding, but should not be greater than in other similar general surgery without bladder irrigation. Hyposmolality did not constitute a problem.

Aged↗