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Biomedical subjects

D Harrington

Publications and source records attributed to D Harrington.

At least 73 records · Page 4Linked to original sources
PubMed1996

Asystoles during infancy recorded by home memory monitors. Benign events?

OBJECTIVES: To assess the frequency and clinical significance of asystole (sinus arrest > or = 2.0 seconds) and the incidence of bradycardia in infants prescribed home cardiorespiratory monitors and to test the hypothesis that asystoles are more likely to occur in preterm infants. DESIGN: Prospective, consecutive sample of monitor printouts. METHODS: All 291 printouts from the memory monitors of 161 patients received during a 2-month period were analyzed. SETTING: University hospital providing primary and referral care. MAIN OUTCOME MEASURES: Asystoles and bradycardias; clinical course of patients with asystoles. RESULTS: Eight patients (5.0%) had 32 episodes of asystole lasting 2.0 to 4.3 seconds (group 1). Fifty-three patients (32.9%) had true bradycardia alarms but no asystoles (group 2). One hundred patients (62.1%) had neither asystoles nor bradycardias (group 3). Preterm infants constituted 88% of group 1 and 81% of group 2 but only 58% of group 3. Infants were more likely to be full-term in group 3 than in the other 2 groups (chi 2, P = .02). Birth weights were lower in group 1 than in group 3 (P < .05, 1-tailed t test). There were 479 true bradycardias; 72.2% lasted 10 seconds or less, 26.3% were longer than 10 seconds but no more than 20 seconds, and 1.5% were longer than 20 seconds. None of the 8 patients with asystoles required resuscitation for their asystoles; all survived and were free of any life-threatening events after their monitors were discontinued and up until their first birthday. CONCLUSIONS: Asystoles occur more commonly in preterm infants; those pauses in the 2.0- to 4.0-second range seem to be benign. Studies of long-term recordings are needed to redefine asystole in both normal preterm and fullterm infants. These data would help further refine current guidelines for pacemaker implantation during infancy.

Birth Weight↗
PubMed1996

Heterogeneity of familial risk in sarcoidosis.

Familial clustering of sarcoidosis and the higher prevalence and clinical severity of sarcoidosis in African Americans suggests etiologic heterogeneity. To test for heterogeneity in familial risk of sarcoidosis, we studied 3,395 siblings and parents of 558 index cases (361 African American, 197 Caucasian) diagnosed at Henry Ford Hospital between 1951 and 1994. Using the age- and sex-specific cumulative incidence of sarcoidosis in our sample, we found a statistically significant heterogeneity in familial risk of disease (P < .001). To determine if this was due to a greater risk of sarcoidosis in African Americans, we recalculated disease probabilities using age-, sex-, and race-specific disease cumulative incidence and found the same amount of heterogeneity in familial risk (P < .001). Index cases (n = 69) from high-risk families were more likely to be African American (odds ratio [OR] = 3.24; 95% confidence interval (CI) = 1.71-6.14) and to have an offspring or second- degree relative affected (OR = 6.21; 95% CI = 2.86-13.45). We conclude that the heterogeneity of familial sarcoidosis risk found in this study is supportive of multiple etiologies. Our results also show that a quantitative assessment of familial risk based on siblings and parents may be a useful screening tool for identifying families with additional affected members. Of the high-risk families, African Americans made up a greater-than-expected percentage even after accounting for differences in disease prevalence. We suggest targeting African Americans for studies of sarcoidosis that focus on Mendelian hypotheses and genetic linkage.

Adult↗
PubMed1996

Development of an L6 myoblast in vitro model of moniliformin toxicosis.

L6 myoblasts were used as an in vitro model to investigate the role of moniliformin and its interaction with monensin in turkey knockdown syndrome and sudden death syndromes in poultry. Cell viability and microscopic and ultrastructural alterations noted in L6 myoblasts cultured in the presence of moniliformin (0.0-0.3 microgram/microliter) were compared to those observed in parallel cultures also containing one of the following compounds: selenium (0-0.004 ng/microliter), thiamine (0-0.3 microgram/microliter), or pyruvate (0-0.46 microgram/microliter). Marked dilation of the RER, membranous whorls, glycogen deposition, membrane-bound cytoplasmic inclusions and necrosis were observed in myoblasts exposed to 0.03-0.30 microgram moniliformin/microliter medium. Supplementation of medium with thiamine and pyruvate, or selenium, provided significant protection to cells exposed to 0.0-0.3 microgram/microliter or 0.0-0.15 microgram moniliformin/microliter, respectively. Dose-dependent differences in protein and ATP production were not detected. Myoblasts grown in medium containing 0-0.15 microgram moniliformin/microliter and 7.5-50.0 microM A23187, beauvericin or monensin had degrees of cytotoxicity similar to parallel cultures receiving only an ionophore. L6 myoblasts were a useful model of moniliformin toxicosis. The findings of this study suggest cytotoxicity due to moniliformin in L6 myoblasts may be due in part to oxidative damage and altered pyruvate metabolism, and that moniliformin does not predispose myoblasts to ionophore toxicosis. This study supports the results of in vivo investigations in poultry that moniliformin and monensin do not act synergistically to induce knockdown or monensin toxicosis.

Adenosine Triphosphate↗
PubMed1996

Survival and growth of Aeromonas hydrophila on modified atmosphere packaged normal and high pH lamb.

The growth of A. hydrophila on normal pH (5.5-5.8) and high pH ( > 6.0) lamb stored under modified atmospheres was examined. Lamb pieces and mince, inoculated with A. hydrophila were packaged in air, vacuum pack, 80% O2/20% CO2, 50% CO2/50% N2, or 100% CO2 and stored at 5 or 0 degrees C for up to 42 days. Samples were examined for the survival and/or growth of A. hydrophila by enrichment in alkaline peptone water and/or direct plating on starch ampicillin agar. The pH of each sample was estimated. On lamb pieces and mince of normal pH, A. hydrophila numbers decreased during storage at 5 and 0 degrees C under all the packaging conditions. The organism was not detected after 21 days storage. In contrast, A. hydrophila numbers were maintained or increased on high pH lamb under most storage regimes. Storage at 5 degrees C allowed significant increases in A. hydrophila numbers on high pH lamb under all the atmospheres, except 100% CO2. In lamb held at 5 degrees C under 100% CO2 for up to 42 days, A. hydrophila was recovered from most samples, although cell numbers decreased during storage. After storage at 0 degrees C, A. hydrophila was recovered from high pH packs stored under all atmospheres. Significant increases in cell numbers were only observed in minced lamb of high pH stored under air or vacuum. The pH values of lamb pieces and mince held at 5 or 0 degrees C under any of the packaging atmospheres did not change in a uniform manner during storage.

Aeromonas hydrophila↗
PubMed1996

Reproducibility of heart rate variability measures in patients with chronic heart failure.

1. In patients with chronic heart failure, heart rate variability is reduced with relative preservation of very-low-frequency power (< 0.04 Hz). Heart rate variability has been measured without acceptable information on its stability and the optimal recording periods for enhancing this reproducibility. 2. To this aim and to establish the optimal length of recording for the evaluation of the very-low-frequency power, we analysed 40, 20, 10 and 5 min ECG recordings obtained on two separate occasions in 16 patients with chronic heart failure. The repeatability coefficient and the variation coefficient were calculated for the heart rate variability parameters, in the time-domain (mean RR, SDRR and pNN50), and in the frequency-domain: very low frequency (< 0.04 Hz), low frequency (0.04-0.15 Hz), high frequency (0.15-0.40 Hz), total power (0-0.5 Hz). 3. Mean RR remained virtually identical over time (variation coefficient 8%). The reproducibility of time-domain (variation coefficient 25-139%) and of spectral measures (variation coefficient 45-111%) was very low. The stability of the heart rate variability parameters was only apparently improved after square root and after log transformation. 4. Very-low-frequency values derived from 5 and 10 min intervals were significantly lower than those calculated from 40 and 20 min intervals (P < 0.005). Discrete very-low-frequency peaks were detected in 11 out of 16 patients on the first 40, 20 and 10 min recording, but only in seven out of 16 when 5 min segments were analysed. 5. The reproducibility of both time or frequency-domain measures of heart rate variability in patients with chronic heart failure may vary significantly. Square root or log-transformed parameters may be considered rather than absolute units in studies assessing the influence of management on heart rate variability profile. Recordings of at least 20 min in stable, controlled conditions are to be recommended to optimize signal acquisition in patients with chronic heart failure, if very-low-frequency power in particular is to be studied.

Chronic Disease↗
PubMed1996

Development of a predictive model for growth of Listeria monocytogenes in a skim milk medium and validation studies in a range of dairy products.

A predictive model based on growth of Listeria monocytogenes in milk is described. The main aim of this work was to generate a predictive model in milk acidified with lactic acid to mimic conditions found in a range of dairy products. A complete factorial design was employed to determine the effects of pH (4.5-7.5), temperature (3-35 degrees C) and salt concentration (0-8%) on growth of the organism. There were 210 design points and growth curves were individually fitted for the Gompertz function using non-linear regression. Descriptors of the curves, such as lag phase duration (LPD), exponential growth rate (EGR) and generation time (GT) were calculated and polynomial models were developed relating these to pH, temperature and salt concentration. The selected cubic polynomial model gave acceptable predictive estimates of growth and was stable, i.e. predictions were repeatable over the range of environmental variables studied. The model was further tested to determine its capacity for predicting growth of listeria in a range of dairy foods and these validation studies confirm its usefulness as a rapid means of estimating growth of the organism under specified environmental conditions.

Animals↗
PubMed1996

Contribution of peripheral chemoreceptors to ventilation and the effects of their suppression on exercise tolerance in chronic heart failure.

OBJECTIVES: To assess the contribution of peripheral chemoreceptors to ventilation and the effects of continuous inspired oxygen on exercise tolerance in chronic heart failure patients. The role of peripheral chemoreceptors in mediating hyperpnoea in chronic heart failure is unknown. Hyperoxia is known to suppress the peripheral chemoreceptor drive. The magnitude of decrease in ventilation with transient inhalations of oxygen thus provides a measure of the contribution of the peripheral chemoreceptors to ventilation. SETTING: Tertiary specialist hospital. SUBJECTS AND METHODS: Three breaths of 100% oxygen were given at rest and also during cycle ergometry at 25 W to 8 healthy controls (age 52.0 (4.7) (SEM) years) and 13 patients with chronic heart failure (age 60.5 (2.1) years (P = NS); radionuclide left ventricular ejection fraction 25.5 (4.3)%). The peripheral chemoreceptor sensitivity was also measured by assessing the ventilatory response to hypoxia using transient inhalations of pure nitrogen. Another group of 12 patients with chronic heart failure (age 65.5 (1.5) years; left ventricular ejection fraction 21.3 (3.0)%) underwent treadmill exercise testing on 2 occasions, breathing air or 100% oxygen in a randomised single-blind manner, to examine the effects of continuous inspired oxygen on exercise tolerance. RESULTS: The reduction in ventilation with transient hyperoxia was 18.1 (2.9)% v 17.9 (2.6)% (P = NS) at rest and 20.4 (2.8)% v 21.0 (1.6)% (P = NS) during cycle ergometry, for controls and patients respectively. The hypoxic chemosensitivity was higher in patients (0.232 (0.022) v 0.572 (0.082) 1/min/%SaO2; P = 0.002). Continuous inspired oxygen increased exercise time (517 (31) v 455 (27) seconds; P = 0.003), and a trend towards a reduction in the ventilatory response to exercise, characterised by the regression slope relating ventilation to carbon dioxide output, was evident (31.27 (2.60) v 34.19 (2.35); P = 0.08). CONCLUSIONS: Despite an increased peripheral chemoreceptor sensitivity, the proportionate contribution of peripheral chemoreceptors to ventilation remained similar in heart failure patients (about 20%). This suggests that the peripheral chemoreceptors are not the main mediator of increased ventilation and there are other non-peripheral chemoreceptor-mediated mechanisms involved. Hyperoxia reduced ventilation at rest and during cycle ergometry. The increase in exercise duration with continuous inspired oxygen that was associated with a reduction in exercise ventilatory response suggests that suppression of the peripheral chemoreceptors may improve exercise tolerance; the effects of possible reduced skeletal muscle anaerobiosis cannot be excluded, however.

Chemoreceptor Cells↗
PubMed1996

Are butter and cheese rich in monounsaturates beneficial in hyperlipidaemic patients?

BACKGROUND: Reduction in intake of dairy products has long been recommended to reduce blood lipids. The value of monounsaturated fatty acids is increasingly recognized. METHODS: We evaluated the effects of a monounsaturate-rich butter and cheese (B) produced by modifying the bovine diet on blood lipid levels of patients with type IIa hyperlipidaemia. We compared their effects with those of normal butter and cheese (A) and polyunsaturate-rich spread and cheese (C). Using a double cross-over design, we studied 30 patients of mean age 56.4 years (23 men, one woman excluded) over 6-week periods. RESULTS: Approximately 35.5 g/day butter/cheese were consumed; no changes in serum total cholesterol, triglycerides, low-density lipoprotein, lipoprotein (a) or cholesterol: high-density lipoprotein (HDL) ratio were observed. HDL levels were higher in B(1.31 mmol/l) than in C (1.22 mmol/l; P < 0.05) and similar to those in A (1.28 mmol/l). HDL2 levels were higher in patients fed diet A(0.23 mmol/l) than they were in those fed diet C (0.19 mmol/l; P < 0.05) and similar to those in patients fed diet B (0.20 mmol/l). Serum HDL3 was significantly higher in patients fed diet B (1.11 mmol/l) than in those fed diet C (1.03 mmol/l; P < 0.05) but similar to that in patients fed diet A (1.06 mmol/l). CONCLUSIONS: Moderate intake of modified dairy products may be of value and deserves further evaluation.

Butter↗
PubMed1996

Subacute leukoencephalitis caused by CNS infection with human herpesvirus-6 manifesting as acute multiple sclerosis.

Several recent reports have documented the neuroinvasiveness of human herpesvirus-6 (HHV-6) in infants with primary HHV-6 infections, in children and adults with AIDS, in recipients of bone marrow transplants, and in immunologically intact adults and children. CNS infections with HHV-6 can be subacute and are frequently associated with diffuse or multifocal demyelination. We analyzed the CNS tissues of a young woman who died of a demyelinative disease, which was clinically and histopathologically diagnosed as acute multiple sclerosis, for active HHV-6 infection by immunohistochemical staining. The tissues contained a dense and disseminated active HHV-6 infection that was intimately related to the pathologic changes present.

Acute Disease↗
PubMed1995

Treatment of nonregenerative anemia with human gamma-globulin in dogs.

Five dogs with nonregenerative anemia were treated with human immunoglobulin as a 12-hour IV infusion, at dosages ranging from 0.5 to 1.5 g/kg of body weight. All dogs had a rapid response to treatment, with reticulocytosis within 1 to 4 days and a substantial increase in hematocrit within 3 to 8 days of treatment. In 2 of 5 dogs, the hematocrit returned to values within reference range and remained in the reference range for 8 to 14 months after treatment, despite discontinuing or tapering prednisone treatment to a low dose. In 3 of 5 dogs, the hematocrit did not return to the reference range. In 1 of these 3 dogs, the hematocrit remained at the new, increased value (26 to 28%) for 248 days after treatment, at which time the dog was euthanatized. In the other 2 dogs, the hematocrit had decreased to pretreatment values by 52 days after treatment. Retreatment of these 2 dogs resulted in a similar, but blunted, response to human immunoglobulin. Human immunoglobulin may be an effective treatment for some dogs with immune-mediated anemia that fail to respond to conventional treatment.

Anemia, Hypochromic↗
PubMed1995

Sources of health care and health needs among children in kinship care.

OBJECTIVES: To determine the characteristics of children in kinship care and their caregivers who have access to health care (a single source of health care or a single provider), and to determine the relation between indicators of access and health needs. DESIGN: Cross-sectional. SETTING: A large eastern city. SUBJECTS: Two hundred ten children selected from households with children in kinship care in April 1989. METHODS: Data were obtained from medical records, access and demographic questionnaires, and a medical and psychologic evaluation. RESULTS: A single facility for health care was reported by 93% of the sample; two thirds of those identified one health care provider. One source of care or one provider was associated with variables such as young age at placement and medical assistance insurance. Children who did not have a single source of care were more likely to have unmet health needs (87% vs 61%, P < .05), especially unmet mental health needs (60% vs 31%, P < .05). CONCLUSIONS: Children in kinship care had good access to health care, but the level of unmet health needs was high. Children who did not have a single source of health care were more likely to have unmet health needs, especially unmet mental health needs. These findings have implications for future health care planning for children in out-of-home care.

Adolescent↗
PubMed1995

Inspiratory muscle strength is a determinant of maximum oxygen consumption in chronic heart failure.

OBJECTIVE: To investigate the significance of respiratory muscle weakness in chronic heart failure and its relation both to maximum oxygen consumption during cardiopulmonary exercise testing and to skeletal muscle (quadriceps) strength. SUBJECTS: Seven healthy men aged 54.9 (SEM 4.3) years and 20 men with chronic heart failure aged 61.4 (1.6) years (P = 0.20) with radionuclide left ventricular ejection fraction of 25.4 (3.0)%. METHODS: Mouth pressures during maximum static inspiratory effort (PImax) at functional residual capacity (FRC) and residual volume (RV) were measured in all subjects and taken as indices of inspiratory muscle strength. Similarly, mouth pressures during maximum static expiratory effort (PEmax) at FRC and total lung capacity (TLC) were taken as indices of expiratory muscle strength. Cardiopulmonary exercise testing was performed in all subjects. All controls and 15 heart failure patients also had their right quadriceps muscle strength measured. RESULTS: There was respiratory muscle weakness in heart failure patients, with reduction of PImax at FRC (59.7) (6.3) v 85.6 (9.6) cm H2O, P = 0.045), PEmax at FRC (94.8 (6.2) v 134.6 (9.1) cm H2O, P = 0.004), and PEmax at TLC (121.7 (8.5) v 160.7 (13) cm H2O, P = 0.028). PImax at RV was also reduced but this did not reach statistical significance (77.3 (6.6) v 89.3 (13) cm H2O, P = 0.44). There was also significant weakness of the right quadriceps muscle (308.5 (22) v 446.2 (28) N, P = 0.001). PImax at both FRC and RV correlated with maximum oxygen consumption (r = 0.59, P = 0.006, and r = 0.45, P = 0.048 respectively) but not PEmax. There was, however, no significant correlation between PImax and right quadriceps strength. CONCLUSIONS: Respiratory muscle weakness is seen in chronic heart failure. The results suggest that inspiratory muscles are important in determining maximum oxygen consumption and exercise tolerance in these patients. The lack of correlation between respiratory and right quadriceps muscle strength further suggests that the magnitude and time course of respiratory and locomotor muscle weakness may differ in individual patients. Treatment aimed at improving the function of the involved muscle groups may alleviate symptoms.

Adult↗
PubMed1995

Family Violence and Development during Adolescence.

Adolescence is a time of major physical, emotional, social, and personal development. This chapter focuses on how these developmental issues are related to the types, causes, outcomes, prevention, and treatment of family violence involving adolescents. As adolescents are not well represented in the family violence literature, the authors conclude the chapter with a section on the need for further research in this area.

Journal Article↗
PubMed1994

Follicular development during early pregnancy and the estrous cycle of the sow.

The objective of this study was to monitor and compare follicle populations and follicular development in pregnant and nonpregnant sows from Day 3 to Day 20 after breeding. Twenty-four sows were paired within parity on the day of artificial insemination and were randomly allocated within pair for insemination with either killed (n=12) or live spermatozoa (n=12). All the sows were artificially inseminated with the pooled ejaculate of the same boar. From Day 3 through Day 20 post estrus, ovarian follicles were scanned daily by ultrasonography. Ultrasound images were recorded on videotape and were retrospectively analyzed. Follicles were mapped to identify the existence of follicular waves. The follicles were then classified as small (< 3 mm), medium (3-5 mm), or large (> or =5 mm). Pregnancy diagnosis was performed on Day 21 by ultrasonography. Pregnant sows maintained a constant proportion of the follicle population in the small, medium and large follicle categories. However, in the nonpregnant sows, the proportion of follicles in the various size categories remained constant until Day 15. Thereafter, the proportion of small follicles decreased (P < 0.05) from Day 15 to 20, and the proportions of medium and large follicles increased (P < 0.05). The predictability of pregnancy status on Day 20 based on follicle populations in any of the 3 follicle categories was low. Moreover, there was no evidence of follicular waves during the estrous cycle or early pregnancy. In conclusion, the proportion of small follicles decreased while medium and large follicle increased from Day 15 through Day 20 of the estrous cycle, but not during a similar stage of pregnancy. This latter finding concurs with follicle recruitment from the pool of small follicles for ovulation following PGF2alpha secretion to induce luteolysis, which reduces progesterone concentrations and thereby allows for the stimulation of the pool of small follicles by gonadotropins.

Journal Article↗
PubMed1994

Sexual abuse: developmental differences in children's behavior and self-perception.

Developmental differences in behavior and self-perception were examined in a group of 44 preschool and school-age children referred for evaluation of sexual abuse and 41 comparison children with no history of sexual abuse, matched on age and gender, and from a similar socioeconomic background. Children suspected of having been sexually abused were rated by their parents as having more internalizing and externalizing problems than comparison children. When children rated their self-competence and social acceptance, there were no group differences between children based on their abuse status; however, there was significant within-group variation among the children suspected of having been sexually abused. Preschool children had elevated scores of perceived competence and social acceptance, and school-age children had depressed scores. There were no age differences among the children in the comparison group. The results suggest that among children suspected of abuse, not only does their self-perception vary by their developmental level, but preschool children may respond with elevated perceptions of themselves. Focusing on individual differences in children's response to suspicions of sexual abuse enables us to identify risk and protective factors that contribute to the psychological outcomes of child sexual abuse.

Child↗
PubMed1994

Maternal HIV infection: parenting and early child development.

Examined whether support could offset the potential stress of maternal HIV infection with regard to parenting and early child development in two studies of low income, urban, drug-using mothers of infants and toddlers. In one study, support was provided through home intervention; in the other, support was measured through self-report. There were few differences in parenting and early child development related to maternal HIV infection. HIV+ mothers reported less child-related stress among their toddlers, more normative levels of child abuse potential following 18 months of home intervention, and displayed more positive involvement with their children. Results, interpreted from ecological theory, suggest that although the early stages of maternal HIV infection may have been too distal to influence the lives of high-risk mothers of infants and toddlers, when differences existed, HIV+ mothers demonstrated more positive attitudes and behaviors toward parenting and were more able to benefit from home intervention than HIV- mothers.

Adult↗