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Biomedical subjects

B J Skipper

Publications and source records attributed to B J Skipper.

At least 55 records · Page 3Linked to original sources
PubMed1990

Effects of temperature and buffer composition on calcium sequestration by sarcoplasmic reticulum and plasma membrane of rabbit renal artery.

45Ca electron microscopic autoradiography was used to examine the effects of buffer composition and temperature on the distribution of calcium in rabbit renal artery smooth muscle cells. The results show that the relative distribution of calcium is dependent on both the buffer used (Tris or Krebs) and the temperature of the bathing solution (25 degrees C or 34 degrees C). Krebs buffer at 34 degrees C gave the highest relative activity in the plasma membrane, sarcoplasmic reticulum, and mitochondria. Buffer and temperature had little effect on the relative activity of the nucleus or cytoplasm. Next, we identified the cellular sites of calcium accumulation after 5, 15, 30, or 60 min exposure to 45Ca in Krebs buffer at 34 degrees C. The results show that sarcoplasmic reticulum and plasma membrane are the primary sites of calcium accumulation during influx into these cells. Although the amount of 45Ca in the cell continues to increase with longer exposure, the relative distribution of calcium is essentially the same after 5 or 60 min. The data also indicate that the relative activity of plasma membrane + sarcoplasmic reticulum (a combination site that includes sarcoplasmic reticulum within a mean distance of 275 nm of the plasma membrane) is similar to the membrane alone and is lower than the sarcoplasmic reticulum alone.

Animals↗
PubMed1990

Fetal hyperinsulinemia and protein turnover in fetal rat tissues.

The effects of fetal hyperinsulinemia on protein turnover in various tissues of fetal rats were determined after transuteral injection of insulin to rat fetuses at day 19 of gestation. Tissue protein content was measured on the subsequent days of gestation (days 20-22), and protein synthesis was determined at day 20 of gestation in fetal tissues after intravenous injection of [3H]phenylalanine into the maternal circulation, followed by measurements of tissue free and protein-bound phenylalanine specific radioactivity in fetal diaphragm, brain, heart, and liver. Rates of protein degradation in these fetal tissues were calculated by subtracting protein accretion rates from rates of protein synthesis. The injection of insulin to rat fetuses at day 19 of gestation resulted in relative macrosomia versus saline-injected controls from the same litter (body wt at day 20 of gestation, 3.26 +/- 0.15 g for saline-injected fetuses and 3.60 +/- 0.25 g for insulin-injected fetuses, P less than 0.001) and increased protein and RNA content of brain, heart, and liver. Although fractional rates of protein synthesis were not significantly elevated in tissues from the hyperinsulinemic fetuses, absolute rates of protein synthesis were increased in brain, heart, and liver of hyperinsulinemic fetuses. Hyperinsulinemia did not reduce calculated rates of protein breakdown in fetal brain, heart, or liver but did in fetal diaphragm. We conclude that the major effect of fetal hyperinsulinemia on protein turnover in rats is to increase protein synthesis in selected tissues without simultaneously affecting protein breakdown.

Amino Acids↗
PubMed1988

Natural history of frequent recurrences of herpes simplex labialis.

We prospectively studied all herpes simplex labialis (HSL) episodes in a group of 84 (age, 6 to 71 years) persons who previously had frequent recurrences of HSL to determine whether their recurrences of HSL were different from those of the general population. The mean +/- standard error for number of HSL outbreaks for 6 months was 2.7 +/- 0.3. Age, gender, or season did not influence the recurrence rate. The mean time to vesicle healing of 214 outbreaks was 6.4 +/- 0.2 days. Again, age or gender did not influence healing time. An episode of HSL did not elicit a refractory period to the next attack of HSL. Furthermore, the severity of the previous HSL lesion did not influence the interval to next recurrence or the location of the next lesion. In 47%, the next recurrence of HSL crossed the midline of the face, and in 45%, it moved from one lip to the other. The high recurrence frequency and multiple facial locations of HSL lesions seen in these persons differed from the general population, who report infrequent lesions of HSL at the same facial location.

Adolescent↗
PubMed1988

Histologic chorioamnionitis in pregnancies of various gestational ages. II: Implications in preterm labor.

A retrospective review of placental materials (membranes, chorionic plate, umbilical cord) derived from preterm birth is reported. All those studied had intact membranes on admission and did not have spontaneous rupture. Those with preterm labor unresponsive to tocolysis, including those with brief and more prolonged labors, were compared with those delivered preterm because of maternal or fetal indications without labor. Those with labor had inflammatory changes in all three sites of greater frequency than those without labor. Those with longer labors had significantly higher rates of inflammation than those without labor. In this population, removing the influence of spontaneous rupture and labor over 6 hours long greatly diminished the likelihood of inferring that inflammation of the choriamniotic environment is a cause of preterm labor unresponsive to tocolysis.

Chorioamnionitis↗
PubMed1988

Diabetes, gallbladder disease, obesity, and hypertension among Hispanics in New Mexico.

Because Hispanics in the Southwest are genetically admixed with American Indians, the hypothesis has been advanced that the excess occurrence of diabetes mellitus, obesity, and gallbladder disease in this ethnic group may be genetic in origin and results from genes derived from American Indians. This report describes the prevalence of these diseases in 1,175 adult Hispanic participants in a survey of a New Mexico community conducted in 1984-1985. At nearly all ages, the majority of subjects had a body mass index of 25 kg/m2 or greater, and a substantial proportion exceeded 30 kg/m2. The prevalence of obesity was much greater in these Hispanics than is shown in nationwide data for US whites. Diabetes mellitus was also reported more often by Hispanic subjects in this survey than by US whites nationwide. A report of gallbladder trouble or of gallbladder removal was common in both males and females; the prevalence of gallbladder removal was as high in this population as in Mexican Americans previously studied in Starr County, Texas. In spite of the high prevalence of obesity, hypertension was less frequent among the New Mexico Hispanics than is shown in nationwide data for US whites. These findings complement those of previous surveys in Texas, which have shown a notably high proportion of adults to be obese, to have non-insulin-dependent diabetes mellitus, and to have gallbladder disease. The similar epidemiology of these diseases in the Hispanics of New Mexico and the Mexican Americans of Texas supports the hypothesis that American Indian admixture underlies the development of these conditions in Hispanics throughout the Southwest.

Adolescent↗
PubMed1988

Discrepancies between self-reported and validated cigarette smoking in a community survey of New Mexico Hispanics.

In a population-based survey of respiratory disease in New Mexico Hispanics, we validated self-reports of cigarette use by 1,317 subjects against salivary cotinine level and end-tidal carbon monoxide concentration. For identifying likely deceivers about cigarette smoking among self-reported never smokers and former smokers, we used cutoff values of 20 ng/ml and 8 parts per million (ppm) for salivary cotinine and carbon monoxide, respectively. Among males and females, age-standardized prevalences of current smokers based upon questionnaire reports were 30.9 and 27.1%, respectively. After adjustment for cotinine alone, these percentages were 36.2 for males and 31.1 for females, and after adjustment for cotinine and carbon monoxide level, the corresponding percentages were 39.1 for males and 33.2 for females. We conclude that self-reports about smoking habits may lead to underestimation of the prevalence of current smokers and that questionnaire responses should be validated with biologic markers of tobacco smoke exposure.

Adolescent↗
PubMed1988

Respiratory diseases and cigarette smoking in a Hispanic population in New Mexico.

We have conducted a cross-sectional study of Hispanic residents of a community in New Mexico. A total of 2,111 subjects were recruited from 733 households; the overall participation rates were 68.1% for males and 78.9% for females. For all subjects, a standardized respiratory symptoms questionnaire was completed, spirometric testing was performed, and saliva and end-tidal breath samples were obtained. As in other populations, chronic respiratory symptoms were uncommon in children, and asthma was more prevalent in boys than in girls. In adults, physician-diagnosed chronic bronchitis and emphysema were less prevalent in this population than in a previously studied sample of non-Hispanic whites in New Mexico. Spirometric testing was confirmatory; less than 1% of the Hispanic males and females had chronic air-flow obstruction. The prevalence of cigarette usage in the Hispanics was comparable to data from non-Hispanic whites in New Mexico and from nationwide surveys. However, daily cigarette consumption by the Hispanics in this sample tended to be low, as found in previous studies in New Mexico and elsewhere.

Adolescent↗
PubMed1988

Spirometric prediction equations for Hispanic children and adults in New Mexico.

We conducted a population-based survey of respiratory diseases and lung function in a New Mexico Hispanic community, and developed spirometric prediction equations based on data from 576 children and adults. Spirometric test procedures were followed as recommended by the American Thoracic Society. For children 6 through 18 yr of age, we used a logarithmic model to predict spirometric parameters. We used simple linear regression for adults 25 through 80 yr of age. On the basis of exploratory analyses, we excluded adult subjects who were obese, defined as a body mass index of 30 kg/m2 or greater. This report describes these regressions. We did not perform regression analysis for those subjects between 19 and 24 yr of age because of small numbers and the inappropriateness of grouping these subjects with older adults for regression analysis. As an alternative to a regression equation for this age group specifically, we propose linear interpolation between values obtained using prediction equations developed for children and for adults. Finally, we compared the percent predicted values obtained from our internal prediction equations with equations from other populations of white children and adults. In general, the comparison equations underestimated the percent predicted values in our population.

Adolescent↗
PubMed1988

Prophylactic knee braces and injury to the lower extremity.

Five hundred and eighty high-school football players were studied over a period of two seasons to determine the effect of so-called prophylactic knee braces on the lower extremity. Two hundred and forty-seven athletes who wore single-hinged braces and eighty-three who wore double-hinged braces were paired for the same season of play with 250 athletes who were similar in height, weight, and playing position but who did not wear braces. The fifty-three injuries of the knee that occurred were significantly more frequent (p less than 0.001) in the group that wore single-hinged braces than in the matched, non-braced group. While there were more injuries of the knee in the participants who were double-hinged braces than in the matched controls, who did not wear braces, the increase in the number of injuries was not significant. There was also a dramatic increase (p less than 0.01) in the number of injuries of the ankle and foot in the athletes who wore braces. Our results question the efficacy of the braces that were studied and call attention to the potentially adverse effect of the braces on adjacent joints in the ipsilateral limb.

Adolescent↗
PubMed1987

Localization of calcium in vas deferens using 45Ca EM autoradiography: relationship to species and the effect of 45Ca removal.

The distribution of calcium was determined in the vas deferens of the guinea pig using 45Ca electron microscopic autoradiography of rapidly frozen, freeze-dried, and embedded tissue. A selective accumulation of calcium at the plasma membrane and SR was observed in vas deferens that had been incubated in 45Ca for 65-85 min prior to rapid freezing. Rinsing the tissue in nonradioactive calcium for 6 min prior to rapid freezing significantly altered the distribution of calcium among the plasma membrane, mitochondria, and cytoplasmic matrix. The influence of species on the observed distribution of calcium was also examined. The distribution of calcium in the guinea pig vas deferens was not significantly different from that in the rabbit vas deferens when the tissues were prepared under identical conditions.

Animals↗
PubMed1987

Salivary cotinine levels and involuntary tobacco smoke exposure in children and adults in New Mexico.

We conducted a population-based household survey of respiratory disease in 2,029 children and adults and measured salivary cotinine levels by radioimmunoassay in 1,360 nonsmokers and ex-smokers. At all ages median and mean cotinine levels among nonsmokers and ex-smokers increased with the number of smokers in the home. The prevalence of a detectable level of cotinine was about 35% for those not living with a cigarette smoker and was greater with the number of cigarettes smoked by household members. In a multiple logistic regression model, the major determinants of a detectable level of cotinine in children were mother's smoking (odds ratio (OR) = 3.2), father's smoking (OR = 2.1), and smoking of other household members (OR = 4.0). Among adults, the effects of spouse's smoking were smaller with OR = 1.3 and 1.4 for husband's and wife's smoking, respectively. We conclude that in the general population cotinine can be frequently detected in the saliva of nonsmokers, even among those not living with a smoker.

Adolescent↗
PubMed1987

Histologic chorioamnionitis in pregnancies of various gestational ages: implications in preterm rupture of membranes.

A retrospective review of placental material derived primarily from preterm deliveries was conducted and inflammatory changes graded on a scale of 0-3. Reviewers were blind as to the clinical outcomes. Other reviewers, unaware of the pathologic results, surveyed the clinical data, and results were combined for analysis. The findings suggest that placental and membrane inflammation probably precedes preterm spontaneous rupture of membranes in 8-30% of cases without labor. The duration of ruptured membranes and labor enhance the frequency of inflammation. Inflammation is not associated with significant puerperal infection unless cesarean delivery occurs. Perinatal morbidity and mortality were not significantly enhanced nor associated with conservative management of spontaneous preterm rupture of membranes in this population beyond the influence of fetal weight and gestational age.

Birth Weight↗
PubMed1987

The influence of intravenous solution content on ritodrine-induced metabolic changes.

To examine the influence of intravenous (IV) solution content on ritodrine-induced metabolic changes, 25 patients treated with various IV solutions were studied before and after a bolus of fluid, and during IV drug therapy, for the effect of hematocrit, pH, lactate, glucose, and electrolyte concentrations. Results were viewed on a mg/kg/minute ritodrine dosage basis. Dextrose-containing fluids caused a significant elevation of glucose after bolus therapy, and 5% dextrose in water also significantly altered lactate and potassium levels. Dextrose enhanced drug-mediated changes in potassium, sodium, chloride, pH, and lactate. The CO2 content dropped in all patients, regardless of IV content. The best IV solution would appear to be plain lactated Ringer's, and the least desirable, 5% dextrose in water.

Blood Glucose↗
PubMed1986

Exaggerated jaundice in Navajo neonates. The role of bilirubin production.

We have explored further the mechanism of exaggerated neonatal hyperbilirubinemia in the Navajo by determining bilirubin production rates with measurements of endogenous carbon monoxide excretion. Navajo newborns had elevated serum bilirubin concentrations and endogenous carbon monoxide excretion measurements at 2 days of age compared with a Caucasian control population. These findings could not be explained by differences in gestational age, postnatal age, or hemoglobin concentration. We conclude that accentuated bilirubinemia in Navajo neonates is partially due to increased bilirubin production.

Bilirubin↗
PubMed1986

Determinants of lung cancer risk in cigarette smokers in New Mexico.

Although cigarette smoking is the strongest known risk factor for lung cancer, the effects of specific smoking practices have not been completely characterized. The present study examines determinants of lung cancer risk in a population-based, case-control study conducted in New Mexico, 1980-82. The study included 521 cases and 769 controls matched for age, sex, and ethnicity. Either the index subjects or their next-of-kin were interviewed in person to obtain a detailed history of cigarette smoking and information concerning other risk factors. With the use of multiple logistic regression, a model was constructed of the effects of amount smoked, duration of smoking, cigarette type, and smoking cessation on lung cancer risk. Among current smokers, risk increased with each additional cigarette smoked per day (P less than .001). For duration of smoking, the risk per year smoked in individuals 65 years and older was only one-third that in persons under age 65 years. With regard to cigarette type, a somewhat higher risk was found associated with smoking nonfilter cigarettes, but there was no evidence of decreasing risk as the extent of filter smoking increased. Lifelong filter cigarette smokers and smokers of both filter and nonfilter cigarettes were at lower risk than lifelong smokers of nonfilter cigarettes only. In ex-smokers, the pattern of variation of relative risk with amount and duration was similar to that in the current smokers. Excluding those who had stopped for 1 year or less, the relative risk declined exponentially with duration of smoking cessation (P less than .01). These analyses confirm the strong benefits of smoking cessation and indicate possible reduction of risk from smoking filter cigarettes.

Adult↗
PubMed1986

Protein turnover in tissues of the rat fetus following maternal starvation.

The effects of maternal starvation upon protein turnover in various tissues of the fetal rat were determined. Protein synthesis was determined in fetal tissues by the intravenous injection of "massive" amounts of 3H-phenylalanine into the maternal circulation, followed by measurements of tissue free and protein-bound phe specific radioactivity in fetal diaphragm, heart, liver, and brain. Rates of protein degradation in fetal tissues were assessed by subtracting protein accretion rates from protein synthesis. Fractional rates of protein synthesis were minimally affected by maternal starvation in diaphragm, heart, and brain. The major factor contributing to reduced fetal protein accretion in these fetal tissues during maternal starvation was enhanced protein breakdown. These findings differ from those previously reported in young adult rodents following fasting or malnutrition.

Animals↗
PubMed1985

The cellular distribution of calcium in freeze-dried rabbit vas deferens using EM autoradiography.

The role of calcium in initiating smooth muscle contraction is widely accepted. The sources of this calcium are thought to be located both intracellularly and extracellularly. We have recently developed a method by which the cellular localization of calcium in smooth muscle can be determined. This method involves exposing the tissue to 45Ca, rapidly freezing and vacuum dehydrating the tissue, and preparing the tissue for electron microscopic autoradiography (EM ARG). In the present study the distribution of calcium in control and potassium-contracted tissue of the rabbit vas deferens was compared. No significant differences in distribution were observed in the two treatments. This finding provides morphological support for the hypothesis that the calcium used in potassium-induced contraction is primarily of extracellular origin. In addition, significant sequestration by intracellular organelles does not occur during a potassium contraction. In other experiments, the effect of rinsing tissue in cold calcium prior to freezing was investigated. From these data is appears that calcium is removed from the cytoplasmic matrix, plasma membrane, and organelles in a nonuniform manner. Further investigation into these findings should enable us to characterize more precisely the intracellular redistribution of calcium that occurs as a result of a variety of physiological manipulations.

Animals↗