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Biomedical subjects

L Torres

Publications and source records attributed to L Torres.

At least 91 records · Page 5Linked to original sources
PubMed1989

Role of renal nerves in response to volume expansion in conscious newborn lambs.

The present study was designed to determine the influence of renal nerves in mediating the renal response to volume expansion in conscious newborn lambs. Bilateral renal denervation (n = 9) or sham surgery (n = 14) was carried out in newborn lambs 3 to 4 days before performing experiments. Lambs were between 6 and 12 days of age when studied. Chronic denervation did not alter basal neonatal renal function nor renal hemodynamics. Volume expansion with isotonic saline equal to 5% of body weight was associated with a fall in hematocrit and an increase in mean arterial blood pressure, glomerular filtration rate, urine flow rate, and Na+ excretion in intact and denervated lambs. In intact lambs, atrial natriuretic factor increased from 98 +/- 28 to 176 +/- 48 ng/ml during volume expansion and remained elevated for 1 h after volume expansion. In addition, plasma renin activity fell from 21 +/- 5 to 8 +/- 1 ng.ml-1.h-1 and aldosterone levels fell from 160 +/- 24 to 59 +/- 7 pg/ml by 150 min after the start of volume expansion. Similar changes in atrial natriuretic factor, plasma renin activity, and aldosterone were observed in denervated lambs. However, the increase in glomerular filtration rate, Na+ excretion, and fractional excretion of Na+ after volume expansion were significantly less in denervated than in intact lambs. Thus, in the newborn, the renal nerves do not appear to play a role in influencing basal renal hemodynamics and renal function but, as in the adult, the renal sympathetic nervous system does play a role in regulating fluid and electrolyte excretion during hypervolemia.

Aldosterone↗
PubMed1987

Cortisol and the hypercholesterolemia of pregnancy and labor.

Lipids and lipoproteins are known to increase substantially during pregnancy and to decrease rapidly after delivery. The factors responsible for the changes have not been identified, however, they could be related to changes in one or more of the endocrine hormones. Since studies relating lipid and lipoprotein changes to cortisol or estradiol concentrations have not been made, we sought to perform such a study. For this study, we measured cholesterol, HDL-C, VLDL/LDL-C, cortisol, and estradiol concentrations from early gestation through delivery in 32 normal pregnant women. During the course of pregnancy, cholesterol increased from 145 to 211 mg/dl (45%); plasma cortisol increased from 8.6 to 17.8 micrograms/dl (107%); and urinary cortisol increased from 0.10 to 0.177 microgram/mg of creatinine (72%). Further significant increases in cholesterol (256 mg/dl, P less than 0.005) and cortisol (77.6 micrograms/dl, P less than 0.001) occurred during labor, and both decreased after delivery. Pooled correlations were calculated and both cholesterol and VLDL/LDL-cholesterol concentrations were found to be related to plasma cortisol as well as to urinary cortisol (P less than 0.001). Plasma estradiol concentrations increased during pregnancy, but not during labor. The results suggest that the increases in cholesterol during pregnancy and labor could be due, in part, to the metabolic and stress-related increases in cortisol. The studies also suggest that both pregnancy and labor and delivery might be useful "natural" models for studying hormonal mechanisms involved in lipid and lipoprotein metabolism.

Adolescent↗
PubMed1987

Morphometric analysis of epithelial cells of frog urinary bladder. I. Effect of antidiuretic hormone, calcium ionophore (A23187) and PGE2.

Changes in epithelial cell morphology, especially at the apical plasma membrane, are frequently cited as initial evidence for antidiuretic hormone (ADH)-induced increase in membrane permeability. The effects of ADH and agents that alter and modify calcium and prostaglandin concentrations on the morphology and cytology of the epithelial cells of frog (Rana pipiens) urinary bladder are presented using the techniques of transmission and scanning electron microscopy. It was found that, like ADH, calcium ionophore, A23187, produce intense microvilli formation, microfilament mobilization and an increase in the density of granules and membrane associated vesicles, suggesting a prominent role of calcium in these processes. Moreover, our results suggest that these membrane and cytosolic transformations may be mediated in part through prostaglandin formation, as exogenous PGE2 mimicked these effects, and indomethacin, a prostaglandin synthesis inhibitor, attenuated ionophore's effect on luminal cytomorphology. However, unlike ADH, prostaglandins and ionophore inhibit hormonal-induced increase in transepithelial water flow. These results suggest that other components more distal to the luminal membrane, perhaps the basolateral membrane, may be rate-limiting for transepithelial water flow and possibly are regulated by either changes in calcium concentrations or prostaglandins.

Actin Cytoskeleton↗
PubMed1987

Fine needle thyroid aspiration: university hospital experience.

Fine needle thyroid aspiration (FNTA) as a diagnostic tool of thyroid disease was started at the University District Hospital (UDH) in 1983. FNTA was performed in 54 willing patients from December 1984 through December 1985. If no medical contraindications existed, thyroid surgery was recommended in order to assess diagnostic accuracy. Surgery was done in 34 (63%) patients; while not in 20:3 for medical reasons, 2 lost to follow-up, 3 refused, 7 had inappropriate FNTA, and 5 for unknown reasons. None had complications to FNTA. Cytology was classified as Class O: inadequate; Class 1: benign; Class 2: indeterminate; and Class 3: malignant. "Non-benign" cytology was obtained in 14 patients: 7 indeterminate (class 2) and 7 malignant (class 3). Four of these had carcinoma confirmed by surgery. Of the 19 with benign FNTA (class 1) only one has thyroid carcinoma. One patient had inadequate sample (Class O). The sensitivity was 80%, specificity 65%, and diagnostic accuracy 67%. All these statistical values are within the range reported in fifteen reviewed series. Thus, FNTA at UDH had a diagnostic value comparable to that described in the literature. It may be utilized as a safe, reliable tool complementary to clinical data in order to reduce the amount of unnecessary thyroid surgery, carry out earlier diagnoses of malignant nodules and increase the yield of carcinoma among those operated.

Adenocarcinoma↗
PubMed1986

Isolation and Characterization of an Fe(III)-Chelating Compound Produced by Pseudomonas syringae.

The phytopathogenic bacterium Pseudomonas syringae produces a fluorescent pigment when it is grown in iron-deficient media. This pigment forms a very stable Fe(III) complex that was purified in this form by using a novel procedure based on ultrafiltration and column chromatography. The Fe(III) complex has a molecular weight of 1,100 and contains 1 mol of Fe(III). The pigment is composed of an amino acid moiety with three threonines, three serines, one lysine, delta-N-hydroxyornithine, and a quinoline-type fluorescent chromophore. These features and its stability constant (in the range of 10) suggest that the fluorescent pigment of P. syringae is related to the siderophores produced by another Pseudomonas species.

Journal Article↗
PubMed1984

[Percutaneous endoscopic gastrostomy].

The authors describe a technique of gastrostomy performed by gastroscopic endoscopy (percutaneous endoscopic gastrostomy-P.E.G.) P.E.G. was indicated in patients who required gastrostomy feeding and had no contraindications for gastric endoscopy. P.E.G., was performed in 10 patients; 7 had suffered, cerebro-vascular accidents; 2 neoplasms (brain and breast); and 1 a brain trauma. One case was complicated by subcutaneous emphysema of the abdominal wall, with spontaneous cure in 72 hours. In our first patient the cotton guide thread broke, and required a new placement. We use routinely now monofilament nylon as guide thread, without ruptures. These were the only two complications of P.E.G. One patient acquired a replacement of damaged Pezzer catheter, which was easily accomplished. The medicate catheter is not available in our country; we have replaced it by an easily self-made device with good results. P.E.G. can be performed without difficulties in any endoscopy center.

Enteral Nutrition↗
PubMed1984

Chromatograph with external column evaluated for determining breath hydrogen in clinical studies.

A novel breath-hydrogen analyzer involving an external chromatographic column in the form of a cartridge packed with molecular-sieve material and dessicant is described. The instrument incorporates a sintered SnO2 solid-state sensor into the detector, which registers a change in electrical potential in response to the adsorption of reducing gases; ambient room air is drawn through an activated charcoal filter by a small, internal pump and used as the carrier gas. Once calibrated with a gas of known H2 concentration, a digital meter registers the concentration of H2 in an unknown sample of breath air. The response is linear with concentration up to 160 microL/L. The external column is both necessary and effective for screening out contaminating reducing gases. The correlation coefficient for 250 gas samples measured simultaneously with an external-cartridge instrument and with an internal column chromatography is greater than 0.99. Results by the new analyzer corresponded 100% with those by the conventional machine for detecting carbohydrate malabsorption; for diagnosing efficient carbohydrate absorption, results by the two instruments agreed for 96% of the tests.

Adsorption↗
PubMed1983

Synthesis and antiallergenic properties of 3-n-pentadecyl- and 3-n-heptadecylcatechol esters.

A synthetic procedure is described for the preparation of 3-n-pentadecyl- and 3-n-heptadecylcatechols and their acetate and alaninate esters. The Wittig reagent prepared from 2,3-dimethoxybenzyltriphenylphosphonium bromide (III) was coupled with 1-tetradecanal or 1-hexadecanal to give the olefins IV and V, respectively. Catalytic reduction of IV and V followed by demethylation with boron tribromide afforded VIII and IX. The acetates were prepared using acetic anhydride and pyridine, while the alaninates were prepared using N-(tert-butoxycarbonyl)-L-alanine and dicyclohexylcarbodiimide followed by removal of the tert-butoxycarbonyl group with hydrogen chloride gas. The esters were active in guinea pigs in the production of tolerance and desensitization or hyposensitization to poison ivy-type contact dermatitis.

Animals↗
PubMed1983

Two-dimensional echocardiographic diagnosis of left-atrial thrombus in rheumatic heart disease. A clinicopathologic study.

Two-dimensional echocardiographic studies were performed in 293 patients with rheumatic heart disease who underwent open-heart mitral valve surgery during an 18-month period. Diagnostic confirmation of a left atrial thrombus was based on direct inspection of the left atrium during surgery and histopathologic examination. Two-dimensional echocardiographic recordings were reviewed. Of the 293 patients, 33 had left atrial thrombi by two-dimensional echocardiographic criteria. This diagnosis was confirmed at surgery and histopathologic study in 30 (specificity 98.8%). A thrombus was not found in three patients. In 21 other patients, left atrial thrombi were present but were not detected by two-dimensional echocardiography (sensitivity 58.8%). Ten of these 21 had thrombi in the left atrial cavity. In 11 patients, thrombi were located in the left atrial appendage, all of which were missed by two-dimensional echocardiography. Excluding these 11 left atrial appendage thrombi, the sensitivity of two-dimensional echocardiography for detecting left atrial cavity thrombi was 75.0%.

Adolescent↗
PubMed1982

[Thermal stability of carbonates in bone tissue].

The analysis shows that carbonate ions present in the mineral phases of calcified tissues are decomposed in two steps during their ignition. These carbonate ions might be all localised in the phosphate sites of the apatitic structure (B type carbonate apatite). The loss of one important part of carbonate ions at a abnormally low temperature (250 degrees C) might result from an intracristalline reaction between these ions and HPO4(2-) or P2O7(4-) ions present in the apatitic structure.

Animals↗
PubMed1981

Low frequency hereditary deafness in man with childhood onset.

A large kindred of hereditary deaf affected with a progressive sensorineural loss that begins during childhood with the low audiologic frequencies is described. Deafness progresses slowly through adolescence, when losses of up to 70 decibels are often detected. Affected adults present profound losses at all frequencies. Genetically, this deafness is transmitted as a simple, dominant, and autosomal mutation. No associated abnormalities have been detected in studies involving medical examinations, care histories, quantitation of several blood serum components, electrocardiograms, electrophoretograms, and karyotypes.

Adolescent↗
PubMed1980

[Intrahemorrhagic esophagogastroduodenofibroscopy. Survey in the city of Rosario].

1.897 patients with upper gastrointestinal bleeding (UGIB) were studied and the cause was diagnosed in 1.756 (92.6%). The most frequently found pathology was the acute bleeding gastropathy (24.5%). Considering the gastric duodenal and anastomotic ulcer as a whole, in 47.5% of the cases the ulcer was observed. Both pathologies together make out that 72 out of 100 patients with UGIB have bleeding due to an ulcer or gastritis. It comes out that the low incidence of neoplasy as a consequence of UGIB and that the 31% of the diagnosed pathology could not have been diagnosed by X-ray.

Acute Disease↗