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Biomedical subjects

A Paredes

Publications and source records attributed to A Paredes.

At least 73 records · Page 4Linked to original sources
PubMed1987

Idiopathic ventricular fibrillation: inducibility and beneficial effects of class I antiarrhythmic agents.

Ventricular fibrillation in patients without recognizable heart disease is uncommon and electrophysiologic data on such patients is limited. Over a 7 year period, five patients (three men and two women, ranging in age from 24 to 52 years) without demonstrable heart disease underwent electrophysiologic studies with pharmacologic drug testing because of single (four patients) or multiple (one patient) documented episodes of ventricular fibrillation. The arrhythmic event was unrelated to myocardial ischemia or infarction, metabolic or electrolyte disturbances, drug toxicity, preexcitation, or prolonged QT syndromes. In all three patients receiving no antiarrhythmic drugs and in two pretreated with amiodarone, a rapid poorly tolerated ventricular tachyarrhythmia requiring cardioversion was induced by programmed ventricular stimulation with up to two extrastimuli. In all instances, addition of either oral quinidine or oral disopyramide prevented the induction of sustained ventricular arrhythmias. All five patients were placed on antiarrhythmic drug regimens found effective during electrophysiologic studies and remained asymptomatic during follow-up periods ranging from 12 to 93 (mean 52) months. We conclude that in the patients with idiopathic ventricular fibrillation in our study: programmed ventricular stimulation reliably replicated the spontaneous arrhythmia, class I antiarrhythmic agents effectively prevented induction of the arrhythmia in the laboratory, and in contrast to the severity of the presenting arrhythmia, a benign clinical course was observed during long-term therapy with class I antiarrhythmic agents.

Adult↗
PubMed1985

Early postoperative nutritional enhancement utilizing enteral branched-chain amino acids by way of a needle catheter jejunostomy.

Twenty patients who underwent extensive intraabdominal surgical procedures and placement of a needle catheter jejunostomy were prospectively studied to evaluate gastrointestinal tolerance and nutritional enhancement when fed an enteral branched-chain amino acid-enriched diet. At a mean caloric intake of 1,325.75 kcal/day (20.6 kcal/kg per day) and a mean nitrogen intake of 7.64 g/day (0.12 g/kg per day), positive nitrogen balance was achieved 2 to 3 days postoperatively. Total lymphocyte count and levels of transferrin and prealbumin increased significantly (p less than 0.05) during the study. Gastrointestinal tolerance was excellent. Plasma levels of leucine, isoleucine, and valine increased significantly during the study period but remained within the normal range.

Abdomen↗
PubMed1984

[Analysis of diabetic microangiopathy using retinal angiography in 82 children].

Between 1979 and 1983, 116 retinal fluorescein angiographies were performed in 82 insulin-dependent diabetic children aged from 8 to 19 years. Abnormalities were observed in 7% of children with diabetes of less than 5 years duration. Retinal lesions were present in 30% of children with disease of 5-60 years duration. Most of the lesions encountered were capillary dilatations, fluorescein leakages and microaneurysms. The incidence and severity of these lesions increased with the duration of diabetes. Most of them, even of early onset, proved irreversible. It is therefore important to monitor their development by frequent angiographies (every 2 years) and to initiate an intensive treatment of diabetic children from the onset of the disease.

Adolescent↗
PubMed1984

Social correlates of drinking in contrived situations.

This chapter reviews the literature on experimentally created drinking situations with humans. In these experiments, social factors have been alternatively investigated as the dependent and independent variables. The findings of several studies assessing the impact of elements in the drinking environment are summarized. The effects of solitary drinking vs. group drinking have been covered and illustrate the quantitative and qualitative responses elicited. An aspect of this review examines studies that attribute behaviorally integrating effects to alcohol when the beverage is incorporated into certain therapeutic settings. Also illustrated are studies that have attempted to influence drinking behavior in alcoholics by using social contingencies.

Aggression↗
PubMed1984

Simultaneous AV nodal reentrant and ventricular tachycardias.

Simultaneous AV nodal reentrant and ventricular tachycardias were observed during the course of an electrophysiological study in a 51-year-old patient who suffered from recurrent attacks of sustained ventricular tachycardia. Occurrence of simultaneous tachycardias was facilitated by the fact that both tachycardias had a similar cycle length. Ventricular tachycardia was most probably initiated by AV nodal tachycardia previously induced by atrial extrastimulation following the administration of atropine.

Anti-Arrhythmia Agents↗
PubMed1983

Influenza B virus infections in the community and the family. The epidemics of 1976-1977 and 1979-1980 in Houston, Texas.

Influenza B virus epidemics occurred in Houston, Texas, in 1976-1977 and 1979-1980. Among families with young children followed longitudinally in the Houston Family Study, 112 infections were detected during 511 person-years of observation. The infection rates for the two epidemics were similar--24 per cent and 20 per cent--although the two epidemics differed greatly in the community. The first epidemic was much more intense with a mid-winter peak that produced school absentee rates above 12 per cent for four consecutive weeks. The indolent epidemic of 1979-1980 smoldered from late September to mid-April with a peak during the second week of March for which school absenteeism did not exceed 8 per cent. In the Houston Family Study population, the combined infection rate for the two outbreaks was highest at 35 per 100 person-years for school children aged 6-19 years. Preschool children aged 7 months-5 years and adults had infection rates of 31 and 16 per 100 person-years, respectively. Preexisting neutralizing antibody titers greater than or equal to 3.5 log2 protected against influenza B infection and illness. Preschool children above 6 months of age, school age children, and parents introduced infection into the family at rates of 15, 15, and 9 per 100 person-years, respectively. Three second introductions were observed. The secondary infection rate was highest among school aged children at 61 per 100 persons at risk.

Adolescent↗
PubMed1982

Breast-feeding and respiratory virus infection.

Thirty-nine breast-fed and 42 bottle-fed infants were followed up from birth over a four-year period. Virus infection was documented by culture and serologic testing, and history and physical examination were recorded for all episodes of respiratory illness. There were no statistically significant differences in rates or distributions of infection with individual viruses or with all viruses over the first three or six months or during the second six months of life in the two groups, nor were there statistically significant differences in rates or distributions of disease of the upper and lower respiratory tract or total respiratory disease, except for decreased disease of the lower respiratory tract in bottle-fed infants in the second six months. There were trends to decreased morbidity in breast-fed infants in the first three and six months and more episodes of pneumonia and bronchiolitis in bottle-fed infants in the first six months (P less than .05) but similar use of medical care by both groups. High cord blood titers to two viruses were not associated with evidence of breast-feeding protection from infection with those two agents. Breast-fed babies do not have fewer respiratory virus infections or illnesses but may experience less severe illness.

Breast Feeding↗
PubMed1981

Risk of respiratory syncytial virus infection for infants from low-income families in relationship to age, sex, ethnic group, and maternal antibody level.

The risk for hospitalization with respiratory syncytial virus infection during the first year of life was about five per 1,000 live births per year for infants born to low-income families in Houston from 1975 to 1979. The risk varied depending upon the intensity of the epidemic for a given season, the month of birth of the infant, and the level of passively acquired maternal antibody at the time of birth. Over 80% of the children hospitalized were less than 6 months of age; thus, most were born during the six months preceding the peak of RS virus activity. The neutralizing antibody titers in cord sera of 68 infants with culture-proven infections before 6 months of age were significantly lower than those of 575 randomly selected cord samples of infants born during the same period. The level of antibody at the time of birth was directly correlated with age at the time of infection. In addition, infants with more severe illnesses had lower levels of antibody in serum collected near onset of illness than did infants with milder illnesses. These observations demonstrate protection against RS infection in early infancy that is correlated with the level of maternal antibody, but it is not known if this protection is mediated directly by the passively acquired antibody or by some other mechanism.

Age Factors↗
PubMed1981

Infection with influenza A/Victoria virus in Houston families, 1976.

In 1976, an epidemic caused by infections with an influenza virus antigenically similar to A/Victoria/75 (H3N2) occurred in Houston, Texas. During this outbreak, 37 families (155 members) enrolled in the Houston Family Study were under observation. The families lived throughout the metropolitan area (Houston, Texas), and were representative of low income groups. The overall frequency of infection in family members was 27.7%. The frequency of infection was the highest for infants under one year of age and for their older siblings, 14 (37.8%) of 37 and 17 (33.3%) of 51, respectively. Eighteen (48.6%) of the 37 families had at least one infected member. Twelve of the 18 'infected' families had school aged children, whereas only three of the 19 'non-infected' families had school aged children (P less than 0.01). These infected families were also larger and had increased household density (persons/rooms). The levels of pre-existing HI antibodies to A/Victoria/75 and A/Port Chalmers/73 were inversely related to frequencies of infection and illness associated with A/Victoria/75 virus. Three children required hospitalization as direct consequence of their infection with this H3N2 influenza virus. Antibody response to infection was related to previous experience with antigenically-related influenza A (H3N2) viruses according to Francis', 'doctrine of original antigenic sin.'

Antibodies, Viral↗
PubMed1981

Patterns of shedding of myxoviruses and paramyxoviruses in children.

In the Houston Family Study, young children were cultured for virus weekly or biweekly and during acute respiratory illnesses. The interval between the onset of illness and positive culture was examined for 179 infections during 1975-1979. In week 1 after onset, 73%, 73%, and 66% of cultures were positive for influenza A virus, respiratory syncytial virus (RSV), and parainfluenza virus type 3, respectively. Pooled data from influenza B virus infections in 1977 and 1980 showed that 73% of cultures were positive in week 1. Influenza A virus in week 2 or RSV in weeks 2 and 3 was isolated from very few children. However, 37% of cultures were positive for influenza B virus during week 2, and 17% of cultures were still positive for parainfluenza virus type 3 during week 3. Shedding of parainfluenza virus type 3 on days 29-38 was also observed. Parainfluenza virus type 3, RSV, and influenza A virus were isolated up to six days before the onset of illness.

Adolescent↗
PubMed1980

Influenza in children. Relationship to other respiratory agents.

During the 1975-1976 respiratory disease season, influenza A/Victoria virus exceeded respiratory syncytial (RS) virus as a cause of lower respiratory tract disease (LRD) in children admitted to the hospital. This was a reversal of their usual roles in the etiology of LRD; however, the importance of influenza viruses in causing serious disease in children has been underestimated because of failure to appreciate the full spectrum of disease associated with influenza virus infections. In addition to those with LRD, several children were hospitalized with nonspecific febrile illnesses or CNS involvement. Furthermore, in the ambulatory care setting, influenza viruses were the most important cause of illness that necessitated children's being brought for medical care during a three-year period. During the peak of epidemics, influenza viruses appeared to interfere with the spread of other major respiratory viruses--particularly RS virus.

Adolescent↗
PubMed1980

Epidemiologic observations of influenza B virus infections in Houston, Texas, 1976-1977.

Influenza B virus infections were documented in Houston, Texas, in 726 patients with febrile respiratory illnesses who presented to representative primary care facilities during the 1976-1977 respiratory disease season. This epidemic followed a "herald wave" of illness associated with influenza B during the preceding spring. Over one-half the virus isolates were from children aged 5-19 years, and school absenteeism rates indicated that about 40 per cent of the students in the Houston area were ill enough to miss school during the epidemic. The rapid rise in the number of cases among students after the school holiday recess demonstrated the importance of school attendance for the rapid dissemination of influenza viruses. During the later phase of the epidemic, most of the cases were preschool children and adults. In addition to disease of the respiratory tract, the epidemic was accompanied by cases of Reye's syndrome at a rate expected for an urban area.

Absenteeism↗
PubMed1979

Reinfection with influenza A (H3N2) virus in young children and their families.

The frequency and consequences of reinfection with influenza A virus were studied by longitudinal observation of families for a three-year period in which two epidemics of influenza A (H3N2) occurred. Seven children followed from birth were reinfected 10-25 months after their first infection. Two children were reinfected by the same H3N2 virus while the others were reinfected with a closely related variant. At least five of these reinfections were accompanied by respiratory illness. Reinfection illness was similar to that accompanying primary infection. For children in the second and third year of life during the 1978 epidemic, the rate of infection was the same for those who had been previously infected (seven of 12) as for those who had not been previously infected (22 of 40). Reinfection was detected in 26% of older siblings and 6% of parents. The occurrence of reinfection may have important implications for elucidation of the protective immune response and for development of prophylaxis for influenzal infections.

Antibodies, Viral↗
PubMed1979

Drinking behavior, remission, and relapse: the Rand Report revisited.

Utilizing the Armor, Polich, and Stambul 1976 criteria, the clinical course of patients from 26 treatment programs was studied, with relapse analyses differing from the data reported by Armor et al. The overall rate of remission at 6 mo follow-up was considerably lower (54%) in this study. The data suggest that those alcoholics who chose to reduce their drinking, as an option, experienced a substantial risk of relapse.

Alcohol Drinking↗