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Biomedical subjects

A Gonzalez

Publications and source records attributed to A Gonzalez.

At least 91 records · Page 5Linked to original sources
PubMed1999

Adrenomedullin, a vasodilator peptide implicated in hemodynamic alterations of liver cirrhosis: relationship to nitric oxide.

This prospective cohort study was aimed at investigating the role of adrenomedullin, a potent vasodilator peptide, in liver cirrhosis and its relationship with nitric oxide and cytokines. Overall, 66 consecutive patients with liver cirrhosis and 15 controls matched for age and sex distribution were included. Adrenomedullin levels in patients with cirrhosis were higher than in controls [28.1 (23.5-34.8) vs 21.9 (21.1-26.4) pmol/liter, P = 0.002]. Child class A patients had adrenomedullin levels similar to those of controls, but lower than patients in class B and C, respectively (P = 0.01). Patients with ascites showed more elevated adrenomedullin levels than patients without (P = 0.001). Adrenomedullin levels had significant correlations with aldosterone (r = 0.55; P < 0.001), plasma renin activity (r = 0.49; P < 0.001) and nitrates-nitrites levels (r = 0.52; P < 0.001). Weak correlations were found with tumor necrosis factor-alpha and interleukin-6. This study shows that high levels of adrenomedullin in liver cirrhosis correlate with features associated with plasma volume expansion, and suggests that, in late stages of cirrhosis, adrenomedullin might contribute to vasodilatation by increasing the generation of nitric oxide.

Adrenomedullin↗
PubMed1999

Factors affecting ostrich egg hatchability.

Ostrich eggs often have low hatchability (HATCH) rates because they do not lose sufficient weight during incubation. Because egg size, eggshell porosity and thickness (THICK), and length of preincubation egg storage are known to affect egg weight loss during incubation (EWL) and HATCH of chicken eggs, these factors were examined using ostrich eggs. The effects of eggshell porosity (number of large pores per cm2 of shell; LP); and THICK on EWL and HATCH were assessed by categorizing the eggs as having either low, intermediate, or high LP or low, intermediate, or high THICK. Mean EWL was higher (P<0.05) in eggs of the high LP group when compared with eggs in either the low or intermediate LP groups that lost similar amounts of weight during incubation. Mean HATCH was also higher (more than 25%; P<0.10) in eggs with high LP when compared with the HATCH found in eggs having low LP. Eggs from the intermediate LP group had an intermediate HATCH response. Moreover, numbers of LP were positively correlated to both EWL (r2 = 0.64; P<0.0001) and HATCH (r2 = 0.25; P<0.03). Inverse relationships existed between THICK and EWL and between THICK and HATCH according to the order (P< 0.05): eggs of low THICK, highest mean EWL and HATCH > eggs of intermediate THICK, intermediate mean EWL and HATCH > eggs of highest THICK, lowest mean EWL and HATCH. Shell thickness was not correlated to either EWL or HATCH. The influence of egg size on mean LP, THICK, EWL, HATCH, and chick weight (CWT) was assessed. Although THICK was unaffected by egg size, higher LP (P<0.10), EWL (P<0.05), and HATCH (P<0.10) were found in medium-sized eggs when compared with either small or large eggs. The CWT was associated with egg size (P<0.05) according to the order: large eggs, highest CWT > medium eggs, intermediate CWT > small eggs, lowest CWT. Neither EWL nor HATCH was affected by length of preincubation egg storage. Collectively, our findings suggest that 1) ostrich eggs that possess low LP and increased THICK hatched poorly, 2) intermediate-sized eggs hatch best, 3) large eggs produced large chicks, and 4) ostrich eggs can be stored under conditions typically used in the poultry industry for a minimum of 10 d without negatively impacting HATCH.

Animal Husbandry↗
PubMed1999

Interleukin-6, nitric oxide, and the clinical and hemodynamic alterations of patients with liver cirrhosis.

OBJECTIVE: Nitric oxide has been proposed as a mediator of hyperdynamic circulation in cirrhosis. Endotoxin and cytokines induce the synthesis of nitric oxide. The aim of this study was to investigate the relationship between endotoxemia, cytokines, and nitric oxide in patients with cirrhosis, and to correlate these findings with clinical, biochemical, and hemodynamic parameters. METHODS: Clinical, biochemical, and hemodynamic parameters were assessed in 66 patients with cirrhosis and 15 controls. Levels of antidiuretic hormone, plasma renin activity, aldosterone, interferon gamma, interleukin-1, interleukin-6, tumor necrosis factor alpha, endotoxin, and nitrates-nitrites were determined. RESULTS: Mean arterial pressure was lower and interleukin-6, tumor necrosis factor alpha, nitrites-nitrates levels, and endotoxin positivity rates were higher in cirrhotics than in controls (p < 0.005). Mean arterial pressure decreased and interleukin-6 levels increased with worsening of Child score (p < 0.005). Patients with ascites had higher levels of interleukin-6, tumor necrosis factor alpha, and nitrates-nitrites than patients without ascites (p < 0.01). Elevated levels of interleukin-6 were found in patients with encephalopathy grade I, compared with patients without (p < 0.001); this association was independent of the severity of liver disease. In patients with low mean arterial pressure, interleukin-6 levels were higher than in patients with high mean arterial pressure (p = 0.001), whereas tumor necrosis factor alpha and nitrates-nitrites levels were not different. By multivariate analysis, high interleukin-6 levels showed independent associations with the presence of ascites, encephalopathy, and low mean arterial pressure. Only interleukin-6 levels had significant correlations with Child score, plasma renin activity, serum and urinary sodium, and mean arterial pressure (r > or = 0.4, p < 0.005). CONCLUSIONS: Although the activity of the nitric oxide pathway is increased in patients with cirrhosis and might contribute to the hemodynamic alteration, other factors are involved. Interleukin-6, possibly through nitric oxide-independent mechanisms, also might play a role in the vasodilatation of cirrhosis and the pathogenesis of hepatic encephalopathy.

Aged↗
PubMed1999

Different modes of pathogenesis in T-cell-dependent autoimmunity: clues from two TCR transgenic systems.

T lymphocytes constantly flirt with reactivity to self peptides, a price they pay for their ability to recognize foreign peptides presented by self-MHC molecules, and autoreactivity in the T compartment occasionally gives rise to autoimmune disease. Pathology from T-cell autoimmunity can manifest itself through radically different strategies, as we have observed recently in two transgenic models. In the BDC2.5 diabetes model, T cells express a transgene-encoded T-cell receptor (TCR) with reactivity against a pancreatic antigen. This leads to a massive, if often controlled, infiltration of the pancreatic islets. Target cell destruction then results from the local consequences of this local immune/inflammatory process. On the other hand, the arthritic manifestations of the KRN transgenic model are indirect: the transgenic TCR confers a broad autoreactivity, through which T cells stimulate B cells to produce arthritogenic immunoglobulins. These molecules are then sufficient to produce the disease, even in the complete absence of any lymphocytes. Although important questions subsist in this model--how the KRN T cells interfere with B-cell tolerance, what the target of arthritogenic IgG is--its implication is that an isolated T-cell dysregulation may manifest itself through an Ig-mediated disease.

Animals↗
PubMed1999

Dose model for a beta-emitting stent in a realistic artery consisting of soft tissue and plaque.

A model for the description of the near-field dose deposition from a 32p impregnated stent in an arterial system consisting of soft tissue and dense plaque is presented. The model is based on the scaling property of the dose-point-kernel (DPK) function which is extended to a heterogeneous medium consisting of a series of layers of different materials. It is shown that, for each point source originating from the stent surface, the DPK function for water can be scaled consistently along the path through the different layers of material to predict the dose at a given point in the heterogeneous medium. Radiochromic film dosimetry on actual 32p stents is used to test the new model. The experimental setup consists of a water-equivalent phantom in which a stent is deployed and on which a thin layer of polytetrafluoroethylene (PTFE) is deposited to simulate the presence of plaque. Layers of radiochromic films stacked over the phantom are used to measure the dose at distances varying from approximately 0.1 mm to approximately 3 mm from the stent surface with and without PTFE. It is shown that the proposed new DPK model for a heterogeneous medium agrees very well with the experimental data and that it compares favorably to the usual homogeneous DPK model. These results indicate that the new model can be used with confidence to predict the dose in a realistic artery in the presence of plaque.

Angioplasty, Balloon, Coronary↗
PubMed1999

Evaluation of recombinant antigens for serodiagnosis of Chagas' disease in South and Central America.

The commercially available diagnostic tests for Chagas' disease employ whole extracts or semipurified fractions of Trypanosoma cruzi epimastigotes. Considerable variation in the reproducibility and reliability of these tests has been reported by different research laboratories, mainly due to cross-reactivity with other pathogens and standardization of the reagents. The use of recombinant antigens for the serodiagnosis of Chagas' disease is recommended to increase the sensitivity and specificity of serological tests. Expressed in Escherichia coli, as fusion products with glutathione S-transferase, six T. cruzi recombinant antigens (H49, JL7, A13, B13, JL8, and 1F8) were evaluated in an enzyme-linked immunosorbent assay for Chagas' disease. The study was carried out with a panel of 541 serum samples of chagasic and nonchagasic patients from nine countries of Latin America (Argentina, Bolivia, Brazil, Chile, Colombia, El Salvador, Guatemala, Honduras, and Venezuela). The optimal concentration of each recombinant antigen for coating of plates was determined with the help of 125I-labelled recombinant proteins. While the specificity of the epimastigote antigen was 84% because of false positives from leishmaniasis cases, for the recombinant antigens it varied from 96.2 to 99.6%. Recombinant antigens reacted with 79 to 100% of serum samples from chronic chagasic patients. In this way, it is proposed that a mixture of a few T. cruzi recombinant antigens should be employed in a diagnostic kit to minimize individual variation and promote high sensitivity in the diagnosis of Chagas' disease.

Animals↗
PubMed1999

Early postpartum metabolic assessment in women with prior gestational diabetes.

OBJECTIVE: To present the results of early postpartum metabolic assessment in women with gestational diabetes mellitus (GDM), to determine predictive factors for subsequent diabetes, and to investigate the association of postpartum glucose tolerance with other components of the metabolic syndrome. RESEARCH DESIGN AND METHODS: A total of 788 women were evaluated 3-6 months after a GDM pregnancy. A 75-g oral glucose tolerance test (OGTT) was performed. Cholesterol, HDL cholesterol, triglycerides, blood pressure, BMI, and body fat distribution were assessed. Clinical and obstetric history, baseline variables at the diagnosis of GDM, metabolic control during pregnancy, and index pregnancy outcome were compared in women with diabetes and women without diabetes (American Diabetes Association [ADA] criteria) after pregnancy. Multivariate logistic regression analysis was used to ascertain independent predictors of subsequent diabetes. Correlation coefficients were assessed between postpartum glucose tolerance and lipid levels, blood pressure, BMI, and body fat distribution. RESULTS: According to ADA criteria, 588 (74.6%) women were normal, 46 (5.8%) had impaired fasting glucose, 82 (10.4%) had impaired glucose tolerance, 29 (3.7%) had both impaired fasting glucose and impaired glucose tolerance, and 43 (5.4%) had diabetes. Prepregnancy obesity, recurrence of GDM, gestational age at diagnosis of GDM, glucose values in the 100-g OGTT, number of abnormal values in the 100-g OGTT, fasting C-peptide levels in pregnancy, C-peptide/glucose score in pregnancy, insulin requirement in pregnancy, 3rd trimester HbA1c levels, and macrosomia differed significantly in women with subsequent diabetes. Independent predictors of postpartum diabetes were prepregnancy obesity, C-peptide/glucose score during pregnancy, and the number of abnormal values in the 100-g diagnostic OGTT. The area under the postpartum glucose curve was positively associated with BMI, waist circumference, waist-to-hip ratio, triglycerides, and systolic and diastolic blood pressures. CONCLUSIONS: Low C-peptide/glucose score during pregnancy together with prepregnancy obesity and severity of GDM (number of abnormal values in the 100-g diagnostic OGTT) are independent predictors of subsequent diabetes. Our data suggest that regardless of obesity and severity of GDM, a beta-cell defect increases the risk of postpartum diabetes. The association of postpartum glucose tolerance with triglyceride levels, blood pressure, obesity, and regional distribution of body fat suggests that postpartum glucose intolerance anticipates a high-risk cardiovascular profile that comprises other risk factors besides diabetes.

Adult↗
PubMed1998

Metapopulation dynamics, abundance, and distribution in a microecosystem

The experimental fragmentation of landscapes of a natural ecosystem resulted in declines in the abundance and distribution of most species in the multispecies animal community inhabiting the landscapes and the extinction of many species. These declines caused the deterioration of the positive interspecific relation between local population abundance and distributional extent in this community. However, when patches were connected by habitat corridors, an immigration "rescue effect" arrested declines in both abundance and distribution and maintained the observed positive relation between them. These results demonstrate the importance of metapopulation dynamics and landscape connectivity for the persistence of populations in fragmented landscapes.

Journal Article↗
PubMed1998

Increased risk of autoimmune thyroid disease in hepatitis C vs hepatitis B before, during, and after discontinuing interferon therapy.

BACKGROUND: Thyroid gland dysfunction has been reported to occur with variable frequency during interferon alfa (IFN-alpha) therapy in patients with the hepatitis C virus (HCV). We prospectively evaluated if the prevalence of autoimmune thyroid disease in patients with HCV differs from that in patients with the hepatitis B virus (HBV) before, at the end of, and 6 months after stopping treatment with IFN-alpha. METHODS: One hundred thirty-four patients with HCV and 41 patients with HBV were studied. Measurements of serum free thyroxine, free triiodothyronine, thyrotropin, thyroid peroxidase antibodies (TPOAbs), thyroglobulin antibodies (TgAbs), and thyrotropin-binding inhibitory immunoglobulin were performed. RESULTS: Positive levels of TPOAb and TgAb were found in 20% and 11% of patients with HCV compared with 5% and 3% of patients with HBV, respectively. At the end of IFN-alpha therapy, thyroid gland dysfunction was more prevalent in patients with HCV (12%) compared with those with HBV (3%), with thyrotropin levels significantly higher in the HCV group (P = .03). Titers of TPOAb, TgAb, and thyrotropin-binding inhibitory immunoglobulin increased significantly (P = .02, P = .04, and P = .02, respectively) at the end of IFN-alpha therapy in patients with HCV but not in those with HBV. Patients who developed thyroid gland dysfunction were predominantly female (P = .03), had decreased levels of free triiodothyronine (P<.001), and had a higher prevalence of TPOAb (P = .03) before treatment with IFN-alpha. Thyroid gland dysfunction was reversed in 60% of those with HCV 6 months after discontinuing treatment with IFN-alpha. CONCLUSIONS: Patients with HCV are more susceptible than patients with HBV to autoimmune thyroid disease. Systematic screening of thyroid gland function and TPOAb titers in all patients with HCV before, during, and after IFN-alpha therapy appears warranted. This precaution is not necessary for patients with HBV.

Adolescent↗
PubMed1998

A novel experimental apparatus to study the impact of white noise and 1/f noise on animal populations.

This paper reports on the design and construction of a novel apparatus that allows a set of aquatic microcosms to experience complex temporal environmental fluctuations. Replicate microcosms were maintained in 18 water baths with independent environmental controls. We give results from a preliminary experiment designed to look at the effects of varying temperatures with different variance spectra (i.e. white noise or 1/f noise) on single species population dynamics. Matching time series (with identical elements, differently ordered) of environmental temperatures with different Fourier spectra were created for use as input to the apparatus using a novel spectral mimicry method. The apparatus functioned well during the course of the experiment making this an extremely useful research tool. This apparatus now provides ecologists with a means of studying how environmental variability and directional trends in this variability, are filtered and translated by real populations and micro-ecosystems.

Animals↗
PubMed1998

Minimizing hospital length of stay in children undergoing ureteroneocystostomy.

OBJECTIVES: Shortening hospital stay yet not compromising quality of care can result in significant cost savings for children undergoing surgical correction of vesicoureteral reflux. METHODS: We reviewed the medical records of pediatric patients who underwent ureteroneocystostomy between July 1995 and July 1997. A total of 43 patients, aged 0.2 to 18 years (mean 5.2) who all received identical postoperative care, except for their pain management and the time of bladder catheter removal, were included in the study. Twenty-three were treated with intravenous ketorolac tromethamine (Toradol); the remaining 20 received narcotics in the immediate postoperative period. The bladder catheter was removed in less than 24 hours in 22 children, and greater than 24 hours in 21. RESULTS: Patients who received ketorolac tromethamine for postoperative analgesia had on average shorter hospital length of stays than those treated with narcotics (1.4 versus 2.5 days, respectively; P < 0.001). The average stay for children whose bladder catheter was removed within 24 hours postoperatively was significantly shorter than those whose catheter was removed after a 24-hour period (1.4 versus 2.4 days, respectively; P < 0.001). There were no reimplantation failures. One child presented 2 days postoperatively with anemia, which did not require transfusion. CONCLUSIONS: Our review demonstrates that ketorolac tromethamine can be used safely and effectively in children for immediate postoperative analgesia, and that its proper use combined with early catheter removal can reduce the length of hospital stay for pediatric patients undergoing ureteroneocystostomy.

Adolescent↗
PubMed1998

Decreased excretion of nitrate and nitrite in essential hypertensives with renal vasoconstriction.

Most hypertensive patients exhibit increased renal vascular resistance (RVR). This study was designed to investigate whether there exists any relationship between RVR and the production of nitric oxide (NO) in patients with essential hypertension. The study was performed in 49 non-treated patients with mild-to-moderate essential hypertension, and 20 age- and sex-matched normotensive subjects on a controlled sodium diet. Renal hemodynamics was measured in terms of the clearance of para-aminohippuric acid and inulin. Urinary excretion of nitrate and nitrite (NO3- plus NO2-) was determined as an index of NO production. As compared with normotensives, hypertensive patients exhibited higher (P < 0.001) RVR and lower (P < 0.05) urinary excretion of NO3- plus NO2-. With the 100% confidence (upper) limit of the normotensive population as a cut-off point, a subgroup of 30 hypertensives had an abnormally high RVR. The excretion of NO3- plus NO2- was lower (P < 0.005) in hypertensives with high RVR than in normotensives and the remaining hypertensives. No differences were found in the urinary excretion of NO3- plus NO2- between normotensives and hypertensives with normal RVR. Statistically significant associations were seen between diastolic blood pressure and RVR (r = 0.341, P < 0.05) and urinary excretion of NO3- plus NO2- (r = -0.387, P < 0.01) in all hypertensives. These results indicate that there is a subgroup (61%) of hypertensive patients with diminished urine levels of NO3- plus NO2- in which RVR is abnormally increased. Thus, it is suggested that in essential hypertension a diminished renal ability to produce NO by the endothelium may be involved in exaggerated renal vasoconstriction.

Endothelium, Vascular↗
PubMed1998

Severe cytomegalovirus hepatitis in a pregnant woman treated with ganciclovir.

Severe cytomegalovirus (CMV) infection rarely occurs in immunocompetent patients, and the use of specific antiviral therapy in such patients has not been established. Here, we describe an unusual case of severe CMV hepatitis in an apparently immunocompetent pregnant woman treated with parenteral ganciclovir. The drug was well tolerated and progressive, improvement of liver function was observed after antiviral therapy. Aspects related with the use of ganciclovir in the immunocompetent host and in the pregnancy are discussed.

Adult↗
PubMed1998

Epidemic leptospirosis associated with pulmonary hemorrhage-Nicaragua, 1995.

In October 1995, epidemic "hemorrhagic fever," without jaundice or renal manifestations, was reported in rural Nicaragua following heavy flooding; 2259 residents were evaluated for nonmalarial febrile illnesses (cumulative incidence, 6.1%) and 15 (0.7%) died with pulmonary hemorrhage. A case-control study found that case-patients were more likely than controls to have ever walked in creeks (matched odds ratio [MOR], 15.0; 95% confidence interval [CI], 1.7-132.3), have household rodents (MOR, 10.4; 95% CI, 1.1-97.1), or own dogs with titers >/=400 to Leptospira species (MOR, 23.4; 95% CI, 3.6-infinity). Twenty-six of 51 case-patients had serologic or postmortem evidence of acute leptospirosis. Leptospira species were isolated from case-patients and potential animal reservoirs. This leptospirosis epidemic likely resulted from exposure to flood waters contaminated by urine from infected animals, particularly dogs. Leptospirosis should be included in the differential diagnosis for nonmalarial febrile illness, particularly during periods of flooding or when pulmonary hemorrhage occurs.

Adolescent↗
PubMed1998

Methodological issues in the use of survey questionnaires to assess the health effects of torture.

It has become increasingly important to identify torture survivors among subgroups of the American population and to assess the continuing health effects of torture experience. To determine whether survey questionnaires can be effectively used to make such assessments, we reviewed the recent literature on refugee health, on the measurement and treatment of trauma, and in the related areas of survey methodology and cognitive psychology. We conclude that, if properly conducted, the survey approach represents an effective method, and we propose specific recommendations concerning procedures that may be used in surveys of torture survivors to maximize study validity.

Data Collection↗
PubMed1998

Light and excess manganese . Implications for oxidative stress in common bean

The effect of light intensity on antioxidants, antioxidant enzymes, and chlorophyll content was studied in common bean (Phaseolus vulgaris L.) exposed to excess Mn. Leaves of bean genotypes contrasting in Mn tolerance were exposed to two different light intensities and to excess Mn; light was controlled by shading a leaflet with filter paper. After 5 d of Mn treatment ascorbate was depleted by 45% in leaves of the Mn-sensitive genotype ZPV-292 and by 20% in the Mn-tolerant genotype CALIMA. Nonprotein sulfhydryl groups and glutathione reductase were not affected by Mn or light treatment. Ten days of Mn-toxicity stress increased leaf ascorbate peroxidase activity of cv ZPV-292 by 78% in low light and by 235% in high light, and superoxide dismutase activity followed a similar trend. Increases of ascorbate peroxidase and superoxide dismutase activity observed in cv CALIMA were lower than those observed in the susceptible cv ZPV-292. The cv CALIMA had less ascorbate oxidation under excess Mn-toxicity stress. Depletion of ascorbate occurred before the onset of chlorosis in Mn-stressed plants, especially in cv ZPV-292. Lipid peroxidation was not detected in floating leaf discs of mature leaves exposed to excess Mn. Our results suggest that Mn toxicity may be mediated by oxidative stress, and that the tolerant genotype may maintain higher ascorbate levels under stress than the sensitive genotype.

Journal Article↗