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C Valdes

Publications and source records attributed to C Valdes.

11 recordsLinked to original sources
PubMed2003

Methane oxidation and its coupled electron-sink reactions in ruminal fluid.

AIMS: This study was conducted to investigate the occurrence of methane oxidation in the rumen, and to identify the electron-sink reaction coupled to the oxidation if it occurred. METHODS AND RESULTS: Mixed ruminal microbes taken from sheep were incubated with 13CH4. Oxidation of methane, estimated from the flux of 13C to CO2 and microbial cells, occurred, but represented only 0.2-0.5% of the methane produced. Methane oxidation was suppressed by the presence of oxygen, and was also inhibited by 2-bromoethane-sulphonate, and molybdate, but not by tungstate. CONCLUSION, SIGNIFICANCE AND IMPACT OF THE STUDY: Methane could be oxidized anaerobically in the rumen by reverse methanogenesis in consort with sulphate reduction.

Animals↗
PubMed1995

Acute trauma alters morphine clearance.

Trauma is accompanied by changes in liver perfusion and acute phase proteins. Such changes have the potential to alter drug metabolism. There are few studies describing drug disposition in acute trauma. We determined the pharmacokinetics of an intermediate extraction drug, morphine, in trauma patients. Nine patients with an Injury Severity Score (ISS) > or = 16 were studied within 48 hours of trauma. Morphine 5 mg was given intravenously and serial blood and urine samples were drawn to derive pharmacokinetic parameters. Alpha acid glycoprotein (AAG) levels were determined. Total morphine clearance (CL) and volume of distribution (Vss) were decreased compared to established literature values. Area under the curve (AUC) and terminal half-life (T 1/2 alpha) were increased. AAG levels were higher than reference range. Elimination half-life was increased. The decrease we observed in Vss may be attributed to increased binding of morphine by AAG, which is increased after trauma as in our patients. Decreased clearance and increased half-life of an intermediate extraction drug may be explained by increased protein binding, decreased liver blood flow, and reduced hepatocellular function. Decreased clearance of the magnitude observed in these patients could result in drug accumulation. Better understanding of the effects of trauma on the pharmacokinetics of low, high, and intermediate extraction drugs will prevent excessive or suboptimal drug dosing.

Acute Disease↗
PubMed1993

[Ureteroscopy. Our results and complications].

From November, 1987 to December, 1990, 399 cases of ureteral calculi were treated by rigid ureteroscopy (URS). Our success and complication rates are presented. Of these, 99 (25%) had a calculus in the pelvis (78/99), iliac (15/99) or lumbar (6/99) ureter, and 300 (75%) had Sandstrasse in the distal ureter. The cases with Sandstrasse were submitted to ureteroscopy within the first 48-72 hours to remove the ureteral obstruction, prevent hydronephrosis or sepsis and to expedite treatment. If symptomatic, obstructive and/or 7 mm or more in diameter, a nephrostomy tube was placed first whenever there was sepsis [23/300 (7%) of those with Sandstrasse and 3/99 (3%) of those with a ureteral calculus] or marked dilatation of the renal cavities [29/300 (9%) and 6/99 (6%), respectively]. The success rate was 93% for the cases with Sandstrasse versus 85% for those with a ureteral calculus, and the complication rates were 5.7% versus 9%, respectively. The foregoing results confirm the high success rate and scant morbidity of ureteroscopy in the treatment of ureteral calculus and Sandstrasse.

Adolescent↗
PubMed1984

Ultrasound evaluation of female genital tract anomalies: a review of 64 cases.

Sixty-four patients with an ultrasound diagnosis of an anomaly of the female genital tract were studied retrospectively to determine the accuracy and usefulness of sonographic examination of these anomalies in the pregnant (64%) and the nonpregnant (36%) patient. Ultrasound diagnoses in 46 patients with follow-up included: (1) bicornuate/septate uterus in 21 cases, (2) uterus didelphys in 18 cases, (3) cervical and vaginal atresia in three cases, (4) obstructed lower but normal upper genital tract in two cases, and (5) abnormal-appearing uterus in two cases. Ultrasound diagnosis was compared with hysterosalpingographic and/or surgical findings in 43 patients and with physical examination in three patients. Scan results were classified as diagnostic in 26%, confirmatory in 63%, and incorrect in 11%. Ultrasound is a reliable clinically useful method of studying genital tract anomalies in gynecologic patients.

Abortion, Therapeutic↗
PubMed1984

Sonographic diagnosis and classification of anomalies of the female genital tract.

A retrospective study of 68 female patients with sonographic diagnoses of genital tract anomalies was done. Corroboration by hysterosalpingography and/or surgery was available in 47 cases (69 per cent) and by visualization of two cervices on physical examination in three cases (4 per cent). Scan results are categorized as diagnostic, confirmatory, and incorrect. The 50 patients were placed in the following proposed categories: segmental mullerian agenesis (four cases); "peculiar appearing" uterus (three cases); uterus didelphys (19 cases); bicornuate and septate uterus (22 cases); obstructed lower with normal upper genital tract (two cases).

Abnormalities, Multiple↗