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Biomedical subjects

C Torres

Publications and source records attributed to C Torres.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effect of standard rest periods on apnea and weight gain in preterm infants.

This study determined the effect of modifying a single aspect of the intermediate care environment on the incidence of apnea and rate of weight gain in convalescent preterm infants. Twenty-two preterm infants were assigned to experimental and control groups using a randomized, matched-pair design. Over a three-week period, infants in the experimental group were provided a 1 1/2-hour nap period four times a day during which their beds were covered and they were left undisturbed. Control infants received standard nursing care. The infants in the experimental group had more apnea at the start of the study than the control infants but showed a significantly more rapid decline in the incidence of apnea. These infants also gained significantly more weight per day than the control infants. Thus, a simple modification of nursing care that involved minimal increases in nursing time had a beneficial effect on preterm infants.

Apnea↗
PubMed1996

Successive negative contrast in one-way avoidance: effect of thiopental sodium and chlorpromazine.

The successive negative contrast effect on one-way avoidance was induced by shifting rats from a large reward (30 s spent in the safe compartment after completion of the avoidance response, pre-shift phase) to a small reward (1 s, post-shift phase). Under these conditions, the previously learned avoidance response deteriorated (negative contrast) when compared to a control group for which 'safe time' remained constant throughout the experimental situation (1 s). Thiopental sodium at a dose of 5 or 10 mg/kg, but not at 1, 2, 15 or 20 mg/kg i.p., abolished the negative contrast effect, and did not affect performance of the one-way avoidance task. Similar results were found when rats were treated with diazepam (1 mg/kg i.p.). Chlorpromazine at a dose of 0.5 or 1 mg/kg i.p. did not affect negative contrast, although at higher doses (2 or 3 mg/kg) there was an increase in the number of trials needed to reach the criterion for learning the avoidance response. This increase was evident in both pre-shift and post-shift phases, although only in the experimental situations involving a low level of reinforcement (1 s in the safe compartment). On the basis of these results, we tentatively suggest that the successive negative contrast effect in one-way avoidance in rats can be considered a useful pharmacological animal model for research into anxiety.

Animals↗
PubMed1996

Epidemiology, serological markers, and hepatic disease of anti-HCV ELISA-2-positive blood donors.

The epidemiology associated with hepatitis C virus (HCV) infection, serologic reactivity, and hepatic disease related to anti-HCV-positive donors of Granada were researched. From 1990 through 1993, medical and epidemiological information and anti-HCV and HCV RNA testing were evaluated in 46,741 blood donors. Serum samples were obtained for anti-HCV ELISA and RIBA and HCV RNA determination. A liver biopsy was conducted in all anti-HCV positives by confirmatory second-generation RIBA to analyze the hepatic lesion and the presence of HCV RNA. The anti-HCV prevalence was 1.12%. A total of 228 anti-HCV second-generation ELISA positive blood donors were analyzed. Intrafamiliar transmission rate was 1.7%. Transfusion and intravenous drug abuse (IVDA) antecedents were associated with a higher risk of seroconversion. A RIBA-positive result was related to high second- and third-generation ELISA ratios (90%), HCV RNA positivity (89%), and elevated alanine aminotransferase (ALT) levels (88%). Approximately 50% of donors with normal ALT levels had high ELISA ratios and second-generation RIBA and HCV RNA positive results. Of the second-generation RIBA indeterminate results, 42% and 82% of the c22 and 33% and 100% of the c100 reactivities were third-generation RIBA and HCV RNA positive, respectively. Liver biopsy was conducted in 85 donors, 74% of whom had a chronic hepatitis and 83% had detectable HCV RNA levels. Chronic hepatitis was diagnosed in 88% vs 43% of donors with elevated and normal alanine aminotransferase levels, respectively. ELISA and confirmatory HCV RNA determinations should be routinely employed in donor screening. A liver biopsy should be conducted in patients with elevated ALT levels and normal ALT levels when viremic.

Adolescent↗
PubMed1996

Allergic fungal sinusitis: a clinicopathologic study of 16 cases.

Allergic fungal sinusitis (AFS) has been clinicopathologically defined as a noninvasive form of fungal infection. Etiologically, most reported cases have been attributed to pigmented dematiaceous fungi. The authors report 16 cases of AFS from our institution, along with a review of cases from the literature. The patients' age ranged from 8 to 71 years, with a mean age of 25 years. All patients were immunocompetent, although six had a strong history of atopy. Multiple sinuses were affected in all cases; nine patients had bilateral involvement, and seven patients manifested unilateral involvement. Histopathologically, all cases were characterized by the presence of "allergic mucin," with scattered fungal organisms without invasion of mucosa or bone. Fontana-Masson stain identified fungi in all but one case and assisted in distinguishing the pigmented dematiaceous organisms from other septated fungal forms. Accordingly, Fontana-Masson stain can be useful in confirming the diagnosis of AFS in the lack of tissue culture results. Fungal cultures performed on six cases grew Exserohilum (three cases), Bipolaris (one case), Drechslera (Bipolaris) (one case), and Curvularia (one case). All patients were treated with surgical debridement and sinus aeration. Follow-up of at least 6 months was obtained in six cases, of which four showed recurrent disease between 8 months and 4 years after the initial surgical procedure. A literature review showed that the most common etiologic agents were members of the dematiaceous family (81%), with the most common genus being Bipolaris (42%), followed by Curvularia (21.3%). It is believed that type I and III hypersensitivity reactions underlie the pathogenesis of this disease.

Adolescent↗
PubMed1996

Fungal peritonitis in a large chronic peritoneal dialysis population: a report of 55 episodes.

Fungal peritonitis (FP) is a rare but serious complication of chronic peritoneal dialysis (CPD) therapy and is associated with high morbidity and CPD drop-out. Risk factors and management of FP remain controversial. We reviewed our experience with FP in an attempt to identify risk factors and to examine outcome in relation to treatment strategies. Between March 1984 and August 1994, 704 patients were maintained on CPD therapy in our unit. A total of 1,712 episodes of peritonitis were identified among these patients. Fungal peritonitis accounted for 55 (3.2%) of these episodes. The patients on CPD therapy who developed FP were similar to those who did not develop FP with regard to age, gender, underlying etiology for end-stage renal disease, and comorbid disease. Prior antibiotic use was noted in 87.3% of episodes of FP. The peritonitis rate in the patients who developed FP was one episode every 5.1 months compared with one episode every 9.9 patient-months in the CPD patients who did not develop this infection. Candida sp caused 74.5% of the episodes of FP. All patients were treated with antifungal drugs. In 85.5% of infections the Tenckhoff catheter was removed within 1 week of the diagnosis of FP; 31.9% of the patients who had the Tenckhoff catheter removed did not have the catheter replaced because of death or transfer to hemodialysis. In the patients who developed FP, 68.1% had the Tenckhoff catheter replaced; of these patients, 90.6% and 59.4% were on CPD therapy 1 and 6 months after catheter replacement, respectively. We conclude that risk factors identified in our population include peritonitis rate and prior antibiotic use. Fungal peritonitis is rare in our CPD population, and although it leads to significant CPD drop-out, it can be managed in many patients with antifungal therapy, early catheter removal, and temporary hemodialysis. Of the catheters replaced between 2 and 8 weeks after the diagnosis of FP, 91% functioned successfully, allowing continuation of CPD.

Amphotericin B↗
PubMed1996

Overexpression of basal c-fos and c-jun but not of ras oncogenes after Theiler's murine encephalomyelitis virus infection of glial cells.

Constitutive expression of the cellular proto-oncogenes c-fos and c-jun, and in a lesser extent ras, was demonstrated in the glioma cell line C-6 by flow cytometry analysis using specific mono and polyclonal antibodies. Basal expression of the products of the early response genes c-fos and c-jun were increased 66 and 50% when Theiler's murine encephalomyelitis virus (TMEV) infected these cells. No increase in ras transcription could be demonstrated after infection. This activation follows a kinetic reaching maximum values after 60 min and was proportional to the multiplicity of infection used. The described effect was completely abrogated by rabbit antibodies to TMEV but was not altered by normal rabbit serum. Furthermore, an intact infectious virion is needed to detect this effect. Fetal calf serum and lipopolysaccharide stimulation slightly increases c-fos and c-jun expression following a slower kinetics. Cytokine treatment (IL-1 alpha, IL-6, IFN-gamma and TNF alpha), did not induce oncogene over-expression. Therefore, this stimulation seems to be linked to the TMEV infectious process.

Animals↗
PubMed1995

Differential effect of buspirone and diazepam on negative contrast in one-way avoidance learning.

The main aim of the present work was to investigate the effect of buspirone, a 5-HT1A receptor agonist, on successive negative contrast in one-way avoidance learning. Successive negative contrast was induced by shifting rats from a large reward (30 s spent in the safe compartment) to a small reward (1 s). Acute administration of buspirone (0.25, 0.5, 0.75 and 1.0 mg/kg i.p.) did not attenuate the contrast effect, as opposed to that observed for diazepam (1 mg/kg i.p.). The highest dose of buspirone used, however, did interfere with the learning of the avoidance response itself. Chronic buspirone (20 days, 0.5 and 0.75 mg/kg i.p.) did not have any effect on successive negative contrast either. Overall, these results could suggest that the 5-HT1A receptor is not involved in the negative contrast effect studied, quite different to that observed for the gamma-aminobutyric acid (GABA) system. The findings are compared to results obtained with animal models selectively sensitive to some anxiolytic drugs, as are the so-called 'conflict models'.

Animals↗
PubMed1995

The receptor for tumor necrosis factor on murine astrocytes: characterization, intracellular degradation, and regulation by cytokines and Theiler's murine encephalomyelitis virus.

Previous reports have shown that tumor necrosis factor (TNF) exerts a role on the physiology of astrocytes under inflammatory situations. The signalling for biological effects of this and other cytokines are usually exerted through cell surface receptors. In this study, we have demonstrated the presence of a surface TNF alpha receptor type I in murine astrocytes of both SJL/J and BALB/c origin, using 125I-labelled recombinant mouse TNF alpha. A linear Scatchard plot indicates the presence of only one type of receptor with a MW of 58 kDa (Type I TNF receptor) that binds the ligand with a Kd of 1 x 10(-9) M. There are 3,000 copies of this receptor on untreated astrocytes. The results also indicate that receptor-bound TNF is rapidly internalized at 37 degrees C and degraded intracellularly to a principal molecular species which elutes from HPLC reverse-phase columns at 38% acetonitrile rather than at 60%, as native TNF alpha does. The binding is up-regulated by increasing the number of receptors (but not its affinity) by treatments with Theiler's murine encephalomyelitis virus (TMEV), Con A and inflammatory cytokines such as IL-1 alpha, IL-6, and INF-gamma. It is not influenced by vaccinia virus, IL-2, or LPS. This receptor may contribute to the initiation of perpetuation of the immune response which mediates the demyelinating inflammation induced by Theiler's virus.

Animals↗
PubMed1995

Detection of aminoglycoside-penicillin synergy against Enterococcus faecium using high-content aminoglycoside disks.

Thirty-seven Enterococcus faecium strains were screened for high-level aminoglycoside resistance with an agar diffusion test using high-content aminoglycoside disks (300 micrograms of streptomycin and 120 micrograms of gentamicin, tobramycin, kanamycin or amikacin). The inhibition zones obtained were correlated with results of time-kill penicillin-aminoglycoside synergy studies. An 11 mm breakpoint differentiated strains susceptible or resistant to the synergy of streptomycin plus penicillin. Irrespective of the inhibition zones obtained with tobramycin and kanamycin disks, Enterococcus faecium strains never showed synergy with penicillin in combination with these aminoglycosides. Penicillin-amikacin synergy cannot be predicted by the amikacin disks. Nevertheless, even though kanamycin disks do not predict penicillin-kanamycin synergy, they can be used to predict penicillin-amikacin synergy. In summary, high-content streptomycin, gentamicin and kanamycin disks can be used to predict the susceptibility of Enterococcus faecium strains to the synergistic combination of penicillin plus one of the aminoglycosides (streptomycin, gentamicin or amikacin, respectively).

Aminoglycosides↗
PubMed1995

Interaction of arginase with metal ions: studies of the enzyme from human liver and comparison with other arginases.

As determined by atomic absorption, fully activated human liver arginase contained 1.1 +/- 0.1 Mn2+/subunit. Upon dissociation to inactive subunits (< 0.01 Mn2+/subunit), there was decreased intensity and a red shift in the tryptophan fluorescence emission spectra of the enzyme, and the resulting species were markedly sensitive to thermal and proteolytic inactivation by trypsin. Arginine and lysine specifically protected the subunits from heat inactivation. Subunit activation by Mn2+ followed hyperbolic kinetics (Kd = 0.08 +/- 0.01 microM). In addition to Mn2+, Ni2+ and Co2+ converted inactive subunits into active monomers, and favoured their association to the oligomeric state of the enzyme (M(r) = 120,000 +/- 2000). The replacement of Mn2+ by Ni2+ or Co2+ resulted in significant changes in Vmax without any change in the Km values for the substrates (arginine or canavanine) or the Ki value for lysine inhibition. The results support our previous suggestion (Carvajal et al., 1994) that Mn2+ is not essential for substrate binding to arginase, and substantiates the conclusion that species differences may exist in the interaction of arginase with metal ions.

Arginase↗
PubMed1995

Expression of interferon-gamma receptors on murine oligodendrocytes and its regulation by cytokines and mitogens.

Interferon-gamma (IFN-gamma) is a cytokine known to exert an important immunological role on astrocytes and oligodendrocytes. As a receptor for IFN-gamma has been demonstrated on murine astrocytes, we have searched for a specific receptor on the cell surface of pure mouse oligodendrocytes maintained in tissue culture. Using recombinant murine IFN-gamma labelled with 125I, we have established the basic physicochemical parameters of the binding. A single receptor was found with a Kd of 1 x 10(-9) M. The number of receptors per cell was 3000-4000 and its molecular weight, as determined by cross-linking experiments, is 87,000. The binding of IFN-gamma to its oligodendrocyte receptor is saturable, specific and temperature-dependent. The receptor-IFN-gamma complex is quickly endocytosed at 37 degrees (the half-time of maximal internalization is around 1 min). Some cytokines, such as interleukin-1 alpha and interleukin-6, up-regulated the expression of the oligodendrocyte receptor, but others, such as tumour necrosis factor-alpha, did not. A dramatic increase in receptor expression is induced by lipopolysaccharide but it is not detectable after treatment with concanavalin A.

Animals↗
PubMed1994

vanA-mediated vancomycin-resistant Enterococcus spp. in sewage.

Three high-level vancomycin-resistant Enterococcus strains (two Enterococcus faecium and one Enterococcus durans) were recovered from three of eight sewage samples taken from the general sewage collector at Logroño (Northern Spain). The strains were present in the sewage samples at estimated concentrations of ten resistant bacteria/mL, corresponding to about 0.4% of the enterococcal population. The VanA protein was detected in each strain by immunoblotting of membrane extracts of the vancomycin-induced cells, and the vanA gene was demonstrated in the wild strains and their transconjugants by DNA-DNA hybridization. This is the first, confirmed report of vanA mediated vancomycin resistance in E. durans.

Bacterial Proteins↗
PubMed1993

[The family characteristics of overusers of primary care health services].

OBJECTIVE: To discover the family characteristics of overusers of a family medical practice. DESIGN: Descriptive study. SETTING: Sonseca Health Centre (Toledo). PARTICIPANTS: Overusers of the health services at a family medical practice. Variables of structure, family function and their use were studied. MEASUREMENTS AND MAIN RESULTS: The family type of the overusers was described as a nuclear family (61.11%), formed by 2-4 members (76.39%) in a period of decline in their life cycle (72.22%), with a certain level of familial dysfunction (13.4%) and overuse of the health services (70.49%). All these findings concurred with data published on the question. CONCLUSIONS: The study demonstrated the importance of tackling the family as a whole within the primary care field and the relevance of studies which investigate the relationship between family variables and use of services.

Adult↗