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Biomedical subjects

J L Evans

Publications and source records attributed to J L Evans.

At least 19 recordsLinked to original sources
PubMed2004

Additive genetic relationships between heifer pregnancy and scrotal circumference in Nellore cattle.

To estimate heritability (h2) for yearling heifer pregnancy and to estimate the genetic correlation between heifer pregnancy and scrotal circumference, 18,145 records of Nellore heifers exposed to breeding at an age of approximately 14 mo and 25,466 records of contemporary young bulls were analyzed. Heifer pregnancy was considered as a categorical trait, with the value 1 (success) assigned to heifers that were pregnant after rectal palpation approximately 60 d after the end of a 90-d breeding season and the value 0 (failure) otherwise. A single-trait animal model for heifer pregnancy and a two-trait animal model including heifer pregnancy and scrotal circumference were used. Contemporary groups were defined in two ways: including (CG2) or not including (CG1) weaning management of the heifer. Heritability estimates obtained by Method R in single-trait analyses were 0.68 +/- 0.09 and 0.61 +/- 0.10 using CG1 and CG2 definitions, respectively. Heritability estimates for two-trait analyses were 0.69 +/- 0.09 (CG1) and 0.63 +/- 0.08 (CG2) for heifer pregnancy and 0.57 +/- 0.03 (both CG) for scrotal circumference. The genetic correlation estimates between the two traits were 0.20 +/- 0.12 (CG1) and 0.20 +/- 0.13 (CG2). Based on the results of this study, EPD for heifer pregnancy can be used to select bulls for the production of precocious daughters and will be more effective than selecting on scrotal circumference EPD in Nellore cattle. However, scrotal circumference can be incorporated in a two-trait analysis to increase the accuracy of prediction for heifer pregnancy EPD for young bulls. Using contemporary group without heifer weaning management gave higher h2 and, for two-trait analysis, converged more quickly.

Animals↗
PubMed2002

Genetic evaluation of the probability of pregnancy at 14 months for Nellore heifers.

To estimate the heritability for the probability that yearling heifers would become pregnant, we analyzed the records of 11,487 Nellore animals that participated in breeding seasons at three farms in the Brazilian states of São Paulo and Mato Grosso do Sul. All heifers were exposed to a bull at the age of about 14 mo. The probability of pregnancy was analyzed as a categorical trait, with a value of 1 (success) assigned to heifers that were diagnosed pregnant by rectal palpation about 60 d after the end of the breeding season of 90 d and a value of 0 (failure) assigned to those that were not pregnant at that time. The estimate of heritability, obtained by Method R, was 0.57 with standard error of 0.01. The EPD was predicted using a maximum a posteriori threshold method and was expressed as deviations from 50% probability. The range in EPD was -24.50 to 24.55%, with a mean of 0.78% and a SD of 7.46%. We conclude that EPD for probability of pregnancy can be used to select heifers with a higher probability of being fertile. However, it is mainly recommended for the selection of bulls for the production of precocious daughters because the accuracy of prediction is higher for bulls, depending on their number of daughters.

Age Factors↗
PubMed2001

Intervention and policy issues related to children's exposure to environmental tobacco smoke.

BACKGROUND: Children's exposure to environmental tobacco smoke (ETS) is unacceptably high; almost 40% of children in the United States are regularly exposed to ETS. METHODS: This paper presents a review of the literature that evaluates interventions designed to reduce ETS exposure among young children. In addition, it presents the study design for Project KISS (Keeping Infants Safe from Smoke), an intervention designed to utilize exposure-related feedback to increase parents' motivation for ETS reduction and to reduce household ETS levels. Baseline data are presented to illustrate factors that should be addressed in ETS interventions. RESULTS: The literature review demonstrates the dearth of studies in the literature targeting ETS reduction among children. Participants in Project KISS believed that smoking had affected their children's health and were in later stages of motivational readiness to quit smoking than is typically observed. However, they face a number of challenges to smoking, such as high prevalence of nicotine dependence, high prevalence of living with other smokers, and socioeconomic and stress-related barriers. CONCLUSIONS: The policy implications of this research are discussed, and recommendations are made for future research.

Adult↗
PubMed2001

Validity evidence for using a general critical thinking test to measure nursing students' critical thinking.

This study examined validity evidence for using a general test of critical-thinking skills and dispositions to measure nursing students' critical-thinking abilities. Content evidence indicated strong support for the theoretical framework underlying the test but less support for the way in which the critical-thinking constructs were specifically measured. Scores related to critical-thinking skills demonstrated significant but low correlations with grade point averages, were moderately correlated with SAT scores, and were uncorrelated with scores related to critical-thinking dispositions. The evidence suggests that nursing programs may need to reconsider how critical thinking should be measured and evaluated.

Adult↗
PubMed2001

A randomized trial to reduce passive smoke exposure in low-income households with young children.

OBJECTIVE: Passive smoke exposure among children is widespread in the United States; estimates suggest that almost 40% of children who are younger than 5 years live with a smoker. Few randomized studies of passive smoke exposure reduction among children have been conducted, and the impact of interventions that have been evaluated has been limited. The objective of this study was to determine whether a motivational intervention for smoking parents of young children will lead to reduced household passive smoke exposure. METHODS: Project KISS (Keeping Infants Safe From Smoke), a theory-driven exposure reduction intervention targeting low-income families with young children, was a randomized controlled study in which participants-smoking parents/caregivers (N = 291) who had children who were younger than 3 years and who were recruited through primary care settings-were randomly assigned to either the motivational intervention (MI) or a self-help (SH) comparison condition was used. Follow-up assessments were conducted at 3 and 6 months. The MI condition consisted of a 30- to 45-minute motivational interviewing session at the participant's home with a trained health educator and 4 follow-up telephone counseling calls. Feedback from baseline household air nicotine assessments and assessment of the participant's carbon monoxide level was provided as part of the intervention. Participants in the SH group received a copy of the smoking cessation manual, the passive smoke reduction tip sheet, and the resource guide in the mail. Household nicotine levels were measured by a passive diffusion monitor. RESULTS: The 6-month nicotine levels were significantly lower in MI households. Repeated measures analysis of variance across baseline, 3-month, and 6-month time points showed a significant time-by-treatment interaction, whereby nicotine levels for the MI group decreased significantly and nicotine levels for the SH group increased but were not significantly different from baseline. CONCLUSIONS: This study targeted a large sample of racially and ethnically diverse low-income families, in whom both exposure and disease burden is likely to be significant. This is the first study to our knowledge that has been effective in reducing objective measures of passive smoke exposure in households with healthy children. These findings have important implications for pediatric health care providers, who play an important role in working with parents to protect children's health. Providers can help parents work toward reducing household passive smoke exposure using motivational strategies and providing a menu of approaches regardless of whether the parents are ready to quit.

Adult↗
PubMed2001

Protection against oxidative stress-induced insulin resistance in rat L6 muscle cells by mircomolar concentrations of alpha-lipoic acid.

In diabetic patients, alpha-lipoic acid (LA) improves skeletal muscle glucose transport, resulting in increased glucose disposal; however, the molecular mechanism of action of LA is presently unknown. We studied the effects of LA on basal and insulin-stimulated glucose transport in cultured rat L6 muscle cells that overexpress GLUT4. When 2-deoxy-D-glucose uptake was measured in these cells, they were more sensitive and responsive to insulin than wild-type L6 cells. LA, at concentrations < or = 1 mmol/l, had only small effects on glucose transport in cells not exposed to oxidative stress. When cells were exposed to glucose oxidase and glucose to generate H2O2 and cause oxidative stress, there was a marked decrease in insulin-stimulated glucose transport. Pretreatment with LA over the concentration range of 10-1,000 pmol/l protected the insulin effect from inhibition by H2O2. Both the R and S isomers of LA were equally effective. In addition, oxidative stress caused a significant decrease (approximately 50%) in reduced glutathione concentration, along with the rapid activation of the stress-sensitive p38 mitogen-activated protein kinase. Pretreatment with LA prevented both of these events, coincident with protecting insulin action. These studies indicate that in muscle, the major site of insulin-stimulated glucose disposal, one important effect of LA on the insulin-signaling cascade is to protect cells from oxidative stress-induced insulin resistance.

Animals↗
PubMed2000

Effects of metformin and vanadium on leptin secretion from cultured rat adipocytes.

OBJECTIVE: We have reported that glucose utilization regulates leptin expression and secretion from isolated rat adipocytes. In this study, we employed two antidiabetic agents that act to increase glucose uptake by peripheral tissues, metformin and vanadium, as pharmacological tools to examine the effects of altering glucose utilization on leptin secretion in primary cultures of rat adipocytes. RESEARCH METHODS AND PROCEDURES: Isolated adipocytes (100 microL of packed cells per well) were anchored in a defined matrix of basement membrane components (Matrigel) with media containing 5.5 mM glucose and incubated for 96 hours with metformin or vanadium. Leptin secretion, glucose utilization, and lactate production were assessed. RESULTS: Metformin (0.5 and 1.0 mM) increased glucose uptake in the presence of 0.16 nM insulin by 37 +/- 10% (p < 0.005) and 62 +/- 8% (p < 0.0001) over insulin alone, respectively. Metformin from 0.5 to 5.0 mM increased lactate production by 105 +/- 43% (p < 0.025) to 202 +/- 52% (p < 0.0025) and at 1.0 and 5.0 mM increased the proportional rate of glucose conversion to lactate by 78 +/- 18% (p < 0.005) and 166 +/- 41% (p < 0.0025), respectively. At concentrations less than 0.5 mM, metformin did not affect leptin secretion, but at 0.5 mM, the only concentration that significantly increased glucose utilization without increasing glucose conversion to lactate, leptin secretion was modestly stimulated (by 20 +/- 9%; p < 0.05). Concentrations from 1.0 to 25 mM inhibited leptin secretion by 25 +/- 8% (p < 0.005) to 89 +/- 4% (p < 0.0001). Across metformin doses, leptin secretion was inversely related to the percentage of glucose taken up and released as lactate (r = -0.74; p < 0.0001). Vanadium (5 to 20 microM) increased glucose uptake from 20 +/- 7% (p < 0.01) to 34 +/- 13% (p < 0.02) and increased lactate production at 5 microM by 17 +/- 8% (p < 0.025) and 10 microM by 61 +/- 20% (p < 0.02) but did not alter the conversion of glucose to lactate. Vanadium (5 to 50 microM) inhibited leptin secretion by 33 +/- 6% (p < 0.0025) to 61 +/- 8% (p < 0.0001). DISCUSSION: Both metformin and vanadium increase glucose uptake and inhibit leptin secretion from cultured adipocytes. The inhibition of leptin secretion by metformin is related to an increase in the metabolism of glucose to lactate. The inhibition by vanadium most likely involves direct effects on cellular phosphatases. We hypothesize that the effect of glucose utilization to stimulate leptin production involves the metabolism of glucose to a fate other than anaerobic lactate production, possibly oxidation or lipogenesis.

Adipocytes↗
PubMed2000

Hemorrhagic lymphadenopathy as a presenting feature of primary al amyloidosis.

Lymphadenopathy associated with hemorrhage as a presenting feature of primary (AL) amyloidosis has not previously been described. We report two such cases one of whom had an acquired factor X and IX deficiency. The clinical presentations were characterized by sudden spontaneous enlargement of lymph nodes followed by partial regression. In both cases significant delay in diagnosis, and hence treatment, occurred due to the mode of presentation. One patient died with rapidly progressive disease but the other has had an excellent response to therapy with high-dose melphalan (HDM, 200 mg/m2) and peripheral blood stem cell rescue. AL amyloid should be considered in all patients presenting with hemorrhagic lymphadenopathy.

Adult↗
PubMed2000

Alpha-lipoic acid: a multifunctional antioxidant that improves insulin sensitivity in patients with type 2 diabetes.

Alpha-Lipoic acid (LA) is a disulfide compound that is produced in small quantities in cells, and functions naturally as a co-enzyme in the pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase mitochondrial enzyme complexes. In pharmacological doses, LA is a multifunctional antioxidant. LA has been used in Germany for over 30 years for the treatment of diabetes-induced neuropathy. In patients with type 2 diabetes, recent studies have reported that intravenous (i.v.) infusion of LA increases insulin-mediated glucose disposal, whereas oral administration of LA has only marginal effects. If the limitations of oral therapy can be overcome, LA could emerge as a safe and effective adjunctive antidiabetic agent with insulin sensitizing activity.

Administration, Oral↗
PubMed1999

Language sample analysis in the 21st century.

Time requirements inherent in transcription and analysis of spontaneous language samples represent a significant barrier to the regular use of language sample analysis in clinical settings. Taking advantage of the options provided by new large, fast, and affordable personal microcomputers, two language analysis programs, the Systematic Analysis of Language Transcripts and The Child Language Data Exchange System have been developed to provide automated analysis of a wide range of language indices, as well as tools designed to reduce and simplify the time-intensive process of transcribing and analyzing children's language samples from both typical and clinical populations. In this article we provide a historical context for the development of these language analysis programs and a brief introduction to the transcription editors and language sample databases for both systems. In addition, a case study highlighting the interactive use of both analysis systems is provided.

Child↗
PubMed1999

Protein tyrosine phosphatases: their role in insulin action and potential as drug targets.

Protein tyrosine phosphatases (PTPases) are the enzymes responsible for the selective dephosphorylation of tyrosine residues. PTPases function to regulate a wide array of biological responses mediated by growth factors and other stimuli by balancing the cellular level of phosphotyrosine in concert with their counterparts, protein tyrosine kinases. The important roles which PTPases play in regulating intracellular signalling and, ultimately, biological function along with the recent availability of information regarding their structural features has highlighted them as potential targets for pharmacological modulation. This is demonstrated by the increased level of activity directed towards the identification of novel small-molecule PTPase inhibitors. The rationale and potential utility of this drug discovery approach is discussed here, with particular emphasis on its application for the treatment of insulin resistance and Type 2 diabetes.

Journal Article↗
PubMed1999

Additive genetic relationships between heifer pregnancy and scrotal circumference in Hereford cattle.

The objective of this study was to determine an appropriate method for using yearling scrotal circumference observations and heifer pregnancy observations to produce EPD for heifer pregnancy. We determined the additive genetic effects of and relationship between scrotal circumference and heifer pregnancy for a herd of Hereford cattle in Solano, New Mexico. The binary trait of heifer pregnancy was defined as the probability of a heifer conceiving and remaining pregnant to 120 d, given that she was exposed at breeding. Estimates of heritability for heifer pregnancy and scrotal circumference were .138+/-.08 and .714+/-.132, respectively. Estimates of fixed effects for age of dam and age were significant for heifer pregnancy and bull scrotal circumference. The estimate of the additive genetic correlation between yearling heifer pregnancy and yearling bull scrotal circumference was .002+/-.45. Additional analyses included models with additive genetic groups for scrotal circumference EPD for heifer pregnancy or heifer pregnancy EPD for scrotal circumference to account for a potential nonlinear relationship between scrotal circumference and heifer pregnancy. Results support the development of a heifer pregnancy EPD because of a higher estimated heritability than previously reported. The development of a heifer pregnancy EPD would be an additional method for improving genetic merit for heifer fertility.

Aging↗
PubMed1998

Factors associated with repeat mammography in a New York State public health screening program.

Screening mammography is the most effective method for early detection of breast cancer, but repeat mammography rates are not optimal in most populations. Since 1988, New York State has supported a program of breast cancer screening for underserved, uninsured, or underinsured women. The present study was designed to identify sociodemographic and clinical factors associated with failure to return for repeat mammography screening after a negative initial mammogram. Of women initially screened between 1988 and 1991 (N = 9,485), 27 percent obtained repeat mammograms by 1993. The final logistic regression model contained program site, race and ethnicity, family income, and time since last mammogram.

Adult↗
PubMed1998

Field trial of endotracheal intubation by basic EMTs.

STUDY OBJECTIVE: The 1994 basic-EMT (EMT-B) curriculum recommended teaching EMT-Bs the skill of endotracheal intubation. In this study we assessed the success and complication rates of endotracheal intubations in the field by EMT-Bs. METHODS: We conducted a prospective clinical trial over a period of 28 months in an urban out-of-hospital EMS system. Four first-responder EMT-B engine companies with paramedic backup received 10 hours; intubation training in three sessions spread over at least 2 weeks. The training module was similar to that of the 1994 EMT-B curriculum and included at least 10 intubations on manikins. The EMTs used manikins with closed chest cavities to learn assessment of endotracheal-tube placement. Patients were eligible for intubation by the EMTs if they were apneic and older than 15 years. We calculated 95% confidence interval (CIs) for intubation success rates. RESULTS: Sixty-six EMT-Bs passed the training examinations and were authorized to perform intubation in the field. Endotracheal intubation was attempted by EMTs in 103 patients; the attempt was successful in 53 (95% CI, 42% to 61%). All patients who were not intubated by EMT-Bs were intubated by paramedics, with the exception of six cases. One attempt at intubation was made in 52 patients, two attempts in 44, and three in 7. Three unrecognized esophageal intubations occurred. CONCLUSION: EMT-Bs trained in a short course successfully intubated about half the patients they encountered in this study. This low intubation success rate calls into question the validity of the endotracheal-intubation training module in the 1994 EMT-B national curriculum.

Aged↗
PubMed1997

Response latency and verbal complexity: stochastic models of individual differences in children with specific language impairments.

Within-subject statistical modeling techniques were employed to investigate individual differences in the extent to which two possible indicators of processing time predicted changes in utterance complexity during spontaneous discourse for 10 children ages 7;1 to 10;1 with specific language impairments (SLI) who differed in receptive language abilities. The two indicators of processing time that were modeled were response latency and the use of a specific discourse marker (Verbal Pause) that provided children with additional time to respond. Longer response latencies were not a strong predictor of increased utterance length for any of the children. However, results indicated that children with better receptive skills used substantially more verbal pauses than children with both expressive and receptive deficits and that the use of these pauses was a strong predictor of increased utterance length for children with better comprehension skills.

Adult↗
PubMed1997

Economic evaluation of oral sumatriptan compared with oral caffeine/ergotamine for migraine.

We conducted an economic comparison of oral sumatriptan with oral caffeine/ergotamine in the treatment of patients with migraine. Cost-effectiveness, cost-utility and cost-benefit analyses were conducted from societal and health-departmental perspectives. A decision tree was used. Utilities were assigned to health states using the Quality of Well-Being Scale. Simple and probabilistic sensitivity analyses were also carried out. From a societal perspective, using sumatriptan instead of caffeine/ergotamine resulted in an incremental cost-effectiveness ratio of -25 Canadian dollars ($Can) per attack aborted, an incremental cost-utility ratio of -$Can7507 per quality-adjusted life-year (QALY), and a net economic benefit of $Can42 per patient per year (1995 values). From the perspective of the health department, the incremental cost-effectiveness ratio was $Can98 per attack aborted, the incremental cost-utility ratio was $Can29,366 per QALY; the grade of recommendation based on past decisions regarding health technology for adoption into health insurance plans was 'moderate'. Sensitivity analysis showed that the results were robust to relatively large changes in the input variables. The incremental health benefits obtained from using oral sumatriptan rather than oral caffeine/ergotamine were achieved at moderately acceptable incremental costs, if past decisions on the adoption of other health technologies are used as a guide.

Administration, Oral↗
PubMed1997

Environmental producer responsibility.

The Packaging and Packaging Waste Directive (P&PWD) requires manufacturers to take responsibility for recovering packaging waste. This article examines some of the challenges this presents. Product designers must now integrate environmental regulations into product and packaging design. This will entail handling the conflict between the differing requirements of the P&PWD and the Medical Device Directive, and marking products to indicate whether packaging is reusable or recyclable.

Environmental Health↗