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Biomedical subjects

R Gonzalez

Publications and source records attributed to R Gonzalez.

At least 91 records · Page 5Linked to original sources
PubMed1998

Highly water-permeable type I alveolar epithelial cells confer high water permeability between the airspace and vasculature in rat lung.

Water permeability measured between the airspace and vasculature in intact sheep and mouse lungs is high. More than 95% of the internal surface area of the lung is lined by alveolar epithelial type I cells. The purpose of this study was to test whether osmotic water permeability (Pf) in type I alveolar epithelial cells is high enough to account for the high Pf of the intact lung. Pf measured between the airspace and vasculature in the perfused fluid-filled rat lung by the pleural surface fluorescence method was high (0.019 +/- 0.004 cm/s at 12 degrees C) and weakly temperature-dependent (activation energy 3.7 kcal/mol). To resolve the contributions of type I and type II alveolar epithelial cells to lung water permeability, Pf was measured by stopped-flow light scattering in suspensions of purified type I or type II cells obtained by immunoaffinity procedures. In response to a sudden change in external solution osmolality from 300 to 600 mOsm, the volume of type I cells decreased rapidly with a half-time (t1/2) of 60-80 ms at 10 degrees C, giving a plasma membrane Pf of 0.06-0.08 cm/s. Pf in type I cells was independent of osmotic gradient size and was weakly temperature-dependent (activation energy 3.4 kcal/mol). In contrast, t1/2 for type II cells in suspension was much slower, approximately 1 s; Pf for type II cells was 0.013 cm/s. Vesicles derived from type I cells also had a very high Pf of 0.06-0.08 cm/s at 10 degrees C that was inhibited 95% by HgCl2. The Pf in type I cells is the highest measured for any mammalian cell membrane and would account for the high water permeability of the lung.

Animals↗
PubMed1998

Anesthesia for morbidly obese patients.

Bariatric surgery is the most effective method for treating patients with morbid obesity, and participation of the anesthesiologist in the treatment of these patients is more and more frequent. Therefore it is important for anesthesiologists to be familiar with anatomic and physiologic implications and the pharmacologic changes associated with obesity, so they can offer optimal perioperative treatment. The present study describes a series of 37 patients with an average body mass index of 50.3 kg/m2 who underwent bariatric surgery in a third-level teaching hospital in Mexico City. Preoperative assessment, airway management, perioperative treatment, and the incidence of complications are analyzed. We found a high frequency of associated diseases, among which diabetes mellitus and systemic arterial hypertension were the most prominent. Cardiorespiratory complications such as obstructive sleep apnea syndrome and obesity-hypoventilation syndrome were particularly frequent (16.2% and 22.0%, respectively). Both general anesthesia and mixed anesthesia (peridural block plus light general anesthesia) were employed. The incidence of complications related to perioperative and anesthetic management was low. We discuss and propose protocols for the evaluation and management of airway and associated cardiorespiratory complications.

Adult↗
PubMed1998

Idiopathic anterior urethritis in prepubertal and pubertal boys: pathology and clues to etiology.

OBJECTIVES: Records were reviewed to examine the common features of boys with noninfectious anterior urethritis, and to describe the underlying pathology. METHODS: Five cases of anterior urethritis with features typical of this syndrome are reviewed. RESULTS: These cases demonstrate the typical appearance and in 1 case the pathologic diagnosis of squamous metaplasia of the bulbar urethra. CONCLUSIONS: Prepubertal urethrorrhagia is associated with squamous metaplasia of the urethra. The tendency to stricture formation may precede instrumentation of the urinary tract.

Adolescent↗
PubMed1998

Child sexual abuse: a preliminary study.

In 1997, 52 child victims of sexual abuse were examined at Oporto Institute of Forensic Medicine. The authors analysed the data concerning these cases in an attempt to contribute to the elucidation of child sexual abuse, particularly in the north of Portugal.

Journal Article↗
PubMed1998

Effect of capsaicin-containing red pepper sauce suspension on upper gastrointestinal motility in healthy volunteers.

Afferent nerves play a major role in the regulation of gastrointestinal motility. The questions remains if specific food ingredients can selectively activate such fibers. The aim of the study was to investigate the effect of intraesophageal application of a capsaicin-containing red pepper sauce (Tabasco) suspension on upper gastrointestinal motility in a controlled trial. After a baseline recording [esophageal motility, balloon distension, electrogastrogram (EGG)], red pepper or saline solution was infused intraesophageally in seven healthy volunteers. At 30 min gastric emptying and orocecal transit time were determined using a [13C]acetate and H2-lactulose breath test. Infusion of red pepper sauce suspension significantly increased the amplitudes (65.8 +/- 3 to 78.5 +/- 4.7 mm Hg, P < 0.05) and propagation velocity (2.9 +/- 0.3 to 4.25 +/- 0.3 sec, P < 0.05) of esophageal pressure waves and LES pressure (17.8 +/- 1.4 to 23.7 +/- 2.6 mm Hg, P < 0.05). It significantly decreased perception and discomfort threshold of intraesophageal balloon distension, reduced the percentage of normal electrical activity in the EGG, and delayed gastric emptying (saline: T(1/2) 42.9 +/- 12.0 min vs red pepper: T(1/2) 66.8 +/- 19.0 min, P < 0.05). Despite the prolongation of gastric emptying, orocecal transit time was not altered, indicating an actual increase of intestinal transit. Esophageal application of capsaicin-containing red pepper sauce suspension had profound changes on upper gastrointestinal motility, which could improve clearance and protection of the esophagus and could lead to retention of the irritant in the stomach and faster transit through the small bowel.

Adult↗
PubMed1998

Prognostic value of initial renal ultrasound in patients with posterior urethral valves.

PURPOSE: Increased cortical echogenicity and loss of corticomedullary differentiation on the initial renal ultrasound study are said to be predictive of poor renal function in patients with posterior urethral valves. We reviewed ultrasound results in a group of patients with posterior urethral valves to test this hypothesis. MATERIALS AND METHODS: We reviewed the radiology records of 19 patients in year 1 of life with posterior urethral valves seen since 1976 for whom records were available. The degree of corticomedullary differentiation and cortical echogenicity was compared with serum creatinine after 4 days of catheter drainage and creatinine clearance at the most recent followup. RESULTS: Median followup was 96 months. At the last followup the sensitivity, specificity, and positive and negative predictive values of increased cortical echogenicity and loss of corticomedullary differentiation for predicting creatinine clearance less than 69 ml. per minute per 1.73 m.2 were 90, 57, 75 and 80, and 100, 33, 71 and 100%, respectively. CONCLUSIONS: Increased cortical echogenicity and loss of corticomedullary differentiation are relatively insensitive predictors of eventual renal function in boys with posterior urethral valves. In a significant proportion of patients with normal renal function the initial renal ultrasound study revealed echogenic kidneys, although only a small proportion with poor renal function had normal kidneys.

Creatinine↗
PubMed1998

Epidemiologic characterization of American cutaneous leishmaniasis in an endemic region of eastern Venezuela.

The status of American cutaneous leishmaniasis was investigated from 1985 to 1991 to provide an epidemiologic characterization of the disease in Bergantin, a rural community in the northeastern part of Anzoátegui State, Venezuela. The study revealed the presence of the infection during the period analyzed, with an average incidence of 50.2 cases per 10,000 inhabitants and this number has increased 1.5 times during the last two years. Three villages where clinical cases had been recorded were selected for a comparison of their prevalence data. These villages comprise the human population in the high and low altitude limits of Bergantin. Immunologic assessment of the inhabitants used two different antigen preparations to examine responses to parasites associated with the cutaneous and visceral forms of the disease. The leishmanin skin test (LST) was used in a sample of 276 individuals (46.3% of the inhabitants) and resulted in an overall positivity of 16.7%. The percentage of LST positivity varied with age and sex, yet analysis of this response and the prevalence for each village reflected the specific characteristics of these localities. La Montaña, situated at 800 meters above sea level, had the highest prevalence (800 cases per 10,000 inhabitants) and the most positive LST response (21.2%) in comparison with the two other villages situated at a lower altitude (300 meters above sea level).

Endemic Diseases↗
PubMed1998

Alternative techniques for augmentation cystoplasty.

PURPOSE: We discuss conventional intestinal cystoplasty and show how concern about potential complications has led to an interest in alternative methods for cystoplasty. Techniques such as gastrocystoplasty, ureterocystoplasty, vesicomyomectomy (autoaugmentation), seromuscular augmentation, alloplastic replacement and bioprosthetic materials are reviewed. Laboratory and clinical results of these techniques are examined critically to compare advantages, disadvantages and potential applications. MATERIALS AND METHODS: Computer searches of available medical data bases were used to generate a list of relevant publications, including original contributions and review articles, which were then reviewed, compared and summarized. RESULTS: Augmentation cystoplasty is used routinely for treatment of reduced bladder compliance and capacity secondary to infectious, inflammatory, neurogenic and congenital disorders. Sigmoidocystoplasty and ileocystoplasty have become standard techniques but there is renewed interest in alternative techniques due to the relatively high morbidity of intestinal cystoplasty. Alternative techniques have been described to avoid inclusion of intestinal mucosa in the urinary tract while creating a compliant bladder of adequate capacity. These techniques include gastrocystoplasty, vesicomyotomy, seromuscular augmentation, various alloplastic or biodegradable scaffolds and in vitro culture with subsequent grafting of autologous urothelium. Although encouraging animal and human results have been reported, each technique is associated with its own limitations and disadvantages. CONCLUSIONS: While intestinal cystoplasty remains the standard, several alternative techniques show promise. At present only gastrocystoplasty, ureterocystoplasty and seromuscular augmentation should be considered clinically useful.

Animals↗
PubMed1998

Quality of life and antireflux medication use following laparoscopic Nissen fundoplication.

With the advent of minimally invasive techniques, the surgical treatment of gastroesophageal reflux disease has received renewed interest. The efficacy of laparoscopic Nissen fundoplication in eliminating reflux has been documented. This study was undertaken to determine changes in quality of life and cost of antireflux medications after laparoscopic Nissen fundoplication. One hundred patients undergoing laparoscopic Nissen fundoplication between 1992 and 1997 completed questionnaires assessing changes in pre- and postoperative cost and number of antireflux medications, reflux symptoms, and quality of life. The average number of antireflux medications was significantly reduced (1.8 versus 0.3, P < 0.0001) as was the average monthly cost ($170 versus $30, P < 0.0001). Patients reported significant (P < 0.05) symptomatic improvement in postprandial heartburn, nocturnal heartburn, postprandial nausea, postprandial vomiting, dysphagia, and gas/bloating. Patients in this series noted fewer symptoms and used fewer antireflux medications at less cost after laparoscopic Nissen fundoplication. Symptoms commonly thought of as complications of fundoplication (vomiting, dysphagia, gas/bloating) were less common after fundoplication. This report documents the efficacy of laparoscopic fundoplication in improving quality of life and reducing use and cost of antireflux medications.

Adolescent↗
PubMed1998

Management of urethral strictures after hypospadias repair.

PURPOSE: We conducted a retrospective study of patients with strictures after hypospadias repair to identify factors contributing to the development of strictures and to attempt to define an optimal strategy for management. MATERIALS AND METHODS: Patients with the diagnosis of hypospadias who had undergone direct vision internal urethrotomy, urethral dilation or urethroplasty were identified. The original location of the meatus, type of initial repair, subsequent procedures and outcome of the interventions were recorded. RESULTS: A total of 38 patients were identified. Of the 29 patients who were initially treated with direct vision internal urethrotomy or urethral dilation 23 (79%) ultimately required open urethroplasty and did well. Of the 8 patients treated with initial urethroplasty 7 had successful outcomes. Overall success, defined as asymptomatic voiding without fistula or residual stricture, was 78% at a mean followup of 6.3 years. CONCLUSIONS: Stricture disease continues to be a significant complication of hypospadias reconstruction. Initial therapy should be urethral dilation but it should be recognized that the majority of these patients will ultimately require open urethroplasty.

Child, Preschool↗
PubMed1997

Dietary fiber, Hispanics, and breast cancer risk?

The cancer rates of immigrant populations in the United States must be taken into account when looking at the importance of diet and culture as it relates to cancer prevention. Unfortunately, some nutrition studies targeted toward nontraditional white populations have not adequately confronted the issue of cultural meaning in efforts to gather dietary data accurate enough to support nutritional analyses, identify marginal diets, or relate risk to dietary patterns. The study presented here resolves many of the culturally specific issues utilizing awareness, attention, and judicious combination of culturally sensitive qualitative and quantitative research techniques. The importance of such a study in an Hispanic population is based on the fact that the age-adjusted rate of breast cancer in countries such as Mexico is among the lowest in the world. In addition, although one of the fastest-growing minority groups in the United States, Hispanic women living in this country have been shown to have the lowest incidence of the mortality rates from this disease across most geographic regions of the United States. Therefore, one might speculate that dietary factors, which have been shown to play a role in breast cancer prevention, may account for this difference. It is well recognized that the traditional Hispanic diet is rich in protective nutrients such as dietary fiber. It is known that through complex mechanisms, dietary fiber works to reduce the amount of estrogens in the body. Research also indicates that it is the level of endogenous estrogen in the body that may influence the onset of breast cancer. In order to better understand how dietary factors may be associated with breast cancer in Hispanic women, it is important that one develop the proper tools to discern any potential differences. Therefore, we developed an approach to obtaining dietary fiber information from a small cohort of 22 Houston-area Hispanic women as a vanguard study for a larger breast cancer prevention trial. Two separate dietary assessment instruments were utilized, a three-day food record and the Southwest Food Frequency Questionnaire. The mean intake of dietary fiber was 16 g/day according to the food record and 21 g/day according to the SWFFQ. Fruits, vegetables, breads, cereals, and beans provided for most of the participants' dietary fiber intake. These results support evidence that the Hispanic population's dietary fiber intake is higher than that for other groups, and this may help explain the lower incidence of breast cancer among some Hispanic populations.

Aged↗
PubMed1997

The integration of nitrogen and carbon catabolite repression in Aspergillus nidulans requires the GATA factor AreA and an additional positive-acting element, ADA.

The expression of the structural genes of the proline utilization cluster of Aspergillus nidulans is repressed efficiently only when both repressing carbon and nitrogen sources are present. Two hypotheses can account for this fact. One is a direct or indirect competition mechanism between the positive-acting AreA GATA factor, mediating nitrogen metabolite repression, and the negative-acting CreA protein, mediating carbon catabolite repression. The second is to propose that CreA prevents the binding or activity of another, as yet unidentified, positive-acting factor, here called ADA. We show the second possibility to be the correct one, and we localize the new positive cis-acting element within 290 bp of the prnD-prnB divergent promoter.

Aspergillus nidulans↗
PubMed1997

Smooth muscle development in the obstructed fetal bladder.

OBJECTIVES: To evaluate changes in the smooth muscle and connective tissue development in the obstructed and normal fetal bladder. METHODS: The smooth muscle and connective tissue composition of 19 fetal urinary bladders, including those of 9 fetuses with anatomic obstruction and 10 controls free of urologic disease, were analyzed by light microscopy and computer-assisted color image analysis. RESULTS: The bladder wall thickness was markedly increased in obstructed fetuses throughout gestation as compared with that in controls. The disparity in bladder wall thickness increased rapidly during gestation. The percent area density of smooth muscle and connective tissue as well as the ratio of smooth muscle to connective tissue remained the same in the obstructed and normal control fetal bladders. CONCLUSIONS: Although bladder outlet obstruction is associated with a marked increase in bladder wall thickness, the percent of smooth muscle and connective tissue comprising the mural histology remains relatively constant as compared with that of normal fetal controls. This study suggests that bladder outlet obstruction in the fetus is not associated with excess collagen deposition but rather with an increased amount of bladder with normal cellular content and a concomitant increase in smooth muscle development.

Connective Tissue↗
PubMed1997

Direct detection of Mycobacterium tuberculosis using polymerase chain reaction assay among patients with hepatic granuloma.

BACKGROUND: In liver tuberculosis, demonstration of acid bacilli by conventional methods remains futile. Since the definitive diagnosis of liver tuberculosis is based on the histologic evidence of granulomatous process with caseation necrosis, seen in only a third of cases, the diagnosis is made retrospectively by response to empirical anti-tuberculous drug therapy. AIMS: Our objective is to establish a polymerase chain reaction assay for detection of Mycobacterium tuberculosis affecting the liver using the paraffin-embedded liver biopsy specimens obtained from patients with hepatic granulomas. METHODS: As positive control, patients having either "definitive" (n=8) or "presumptive" (n=9) tuberculosis on the basis of clinical, microbiological, histologic data and their positive response to empirical treatment of anti-tuberculous drugs were used. Patients with hepatic granulomas secondary to schistosomiasis (n=6), sarcoidosis (n=2) and other liver diseases (n=10) were used as negative control. RESULTS: Of those patients who were diagnosed as having "definitive" and "presumptive" liver tuberculosis, positivity by one-step polymerase chain reaction was 100% and 44%, respectively. Using the nested polymerase chain reaction, positivity increased to 78% with "presumptive" liver tuberculosis. In contrast, the polymerase chain reaction assays were negative among all patients with hepatic granuloma due to non-tuberculous-in-origin and other liver diseases. CONCLUSIONS: The overall positivity of this polymerase chain reaction assay (88%) compares favorably with that of other conventional methods (12%). Thus, this polymerase chain reaction assay may be a reliable diagnostic tool for liver tuberculosis in a patient population in which the prevalence of diseases associated with hepatic granuloma is common.

Adolescent↗