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Biomedical subjects

Leann Myers

Publications and source records attributed to Leann Myers.

At least 19 recordsLinked to original sources
PubMed2006

Changes in metabolic syndrome variables since childhood in prehypertensive and hypertensive subjects: the Bogalusa Heart Study.

That essential hypertension is associated with metabolic syndrome is known. However, information is scant regarding the course of development of adverse levels of blood pressure and other risk variables of metabolic syndrome in youth at risk for developing hypertension. This aspect was studied, retrospectively, in a community-based cohort of normotensive (n=2206), prehypertensive (n=721), and hypertensive (n=328) subjects examined serially during childhood (4 to 11 years), adolescence (12 to 18 years), and adulthood (19 to 42 years). Prehypertensive subjects versus normotensive subjects had significantly higher body mass index and subscapular skinfold, systolic (SBP) and diastolic (DBP) blood pressures, and triglycerides beginning in childhood; higher glucose in adolescence; and higher low-density lipoprotein cholesterol, fasting insulin, and insulin resistance index in adulthood. Hypertensive subjects versus normotensive subjects had higher adiposity measures, SBP and DBP, glucose, and triglycerides beginning in childhood; higher insulin and insulin resistant index in childhood and adulthood; and lower high-density lipoprotein, cholesterol in adulthood. Most of these variables progressed adversely at an increased rate in prehypertensive and hypertensive subjects. In a multivariate analysis, adverse changes in adiposity, SBP, and DBP were independently associated with prehypertensive status; and adverse changes in adiposity, SBP and DBP, insulin resistant index, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides with hypertension status. As young adults, prehypertensive and hypertensive subjects showed significantly higher prevalence of obesity, hyperinsulinemia, hyperglycemia, and dyslipidemias. Thus, excess adiposity and blood pressure beginning in childhood and accelerated adverse longitudinal changes in risk variables of metabolic syndrome through young adulthood characterize the early natural history of hypertension.

Adiposity↗
PubMed2006

B7-H4 expression identifies a novel suppressive macrophage population in human ovarian carcinoma.

Tumor-associated macrophages are a prominent component of ovarian cancer stroma and contribute to tumor progression. B7-H4 is a recently identified B7 family molecule. We show that primary ovarian tumor cells express intracellular B7-H4, whereas a fraction of tumor macrophages expresses surface B7-H4. B7-H4+ tumor macrophages, but not primary ovarian tumor cells, suppress tumor-associated antigen-specific T cell immunity. Blocking B7-H4-, but not arginase-, inducible nitric oxide synthase or B7-H1 restored the T cell stimulating capacity of the macrophages and contributes to tumor regression in vivo. Interleukin (IL)-6 and IL-10 are found in high concentrations in the tumor microenvironment. These cytokines stimulate macrophage B7-H4 expression. In contrast, granulocyte/macrophage colony-stimulating factor and IL-4, which are limited in the tumor microenvironment, inhibit B7-H4 expression. Ectopic expression of B7-H4 makes normal macrophages suppressive. Thus, B7-H4+ tumor macrophages constitute a novel suppressor cell population in ovarian cancer. B7-H4 expression represents a critical checkpoint in determining host responses to dysfunctional cytokines in ovarian cancer. Blocking B7-H4 or depleting B7-H4+ tumor macrophages may represent novel strategies to enhance T cell tumor immunity in cancer.

Animals↗
PubMed2006

Single-blind, multicenter, placebo controlled, parallel study to assess the safety and efficacy of intralesional interferon alpha-2B for minimally invasive treatment for Peyronie's disease.

PURPOSE: We investigated the efficacy and safety of intralesional interferon alpha-2b for the treatment of Peyronie's disease. MATERIALS AND METHODS: A total of 117 consecutive patients with a mean age of 55.1 years who had Peyronie's disease were enrolled in a single-blind, multicenter, placebo controlled, parallel study to determine the efficacy and safety of intralesional interferon alpha-2b therapy (Schering, Kenilworth, New Jersey), including 62 who received placebo and 55 who received interferon alpha-2b. Saline (10 ml) in controls and interferon alpha-2b (5 x 10(6) U) were administered biweekly for 12 weeks. Each patient was evaluated for penile curvature, plaque size and density, penile pain, erectile function and penile hemodynamics before and after study completion. Improvement in these parameters was statistically compared between the groups. RESULTS: A total of 53 patients in the control arm and 50 in the interferon alpha-2b arm completed the study. Improvement in penile curvature, plaque size and density, and pain resolution was significantly greater in patients treated with interferon alpha-2b vs placebo. The increase in mean International Index of Erectile Function scores was not significantly different between the groups. Penile blood flow improvement was observed in interferon alpha-2b treated patients but not in those who received placebo. The decrease in the number of penile vascular pathologies was significantly higher in interferon alpha-2b cases. Side effects, mostly flu-like symptoms, which were frequently noted in patients on interferon alpha-2b, were mild to moderate in degree and of short duration. CONCLUSIONS: This single-blind, multicenter, placebo controlled, parallel study demonstrates that intralesional interferon alpha-2b at a dose of 5 x 10(6) units biweekly for 12 weeks is effective and safe as minimally invasive therapy for Peyronie's disease.

Adult↗
PubMed2005

Leptin, adiposity, and testosterone in captive male macaques.

Leptin is considered to act as a signal relating somatic energetic status to the reproductive system. However, the nature of that signal and its relationship with male reproductive function across nonhuman primate species are unclear. We suggest that species-specific differences in leptin physiology may be related to the degree of environmental variation and variation in the importance of energy stores for male reproduction. In order to test the role of seasonality in species differences among nonhuman primates, we compared leptin, testosterone, and body composition in male rhesus (n = 69) and pig-tailed (n = 43) macaques. Despite having larger abdominal fat deposits, the rhesus macaques did not exhibit significantly higher leptin levels (rhesus, 2.21 +/- 0.43 ng/ml; pig-tailed, 2.12 +/- 0.39 ng/ml). Both species showed increases in leptin across adolescent, subadult, and adult age-groups (P = 0.036 for rhesus; P = 0.0003 for pig-tailed by ANCOVA). Testosterone was not significantly associated with leptin in either the rhesus (r = 0.039; P = 0.754) or pig-tailed (r = 0.2862; P = 0.066) samples. Comparison of leptin levels across the two species using univariate modeling procedures showed no significant age-group by abdominal fat interaction. These findings suggest little difference in leptin production between these two closely related species, despite the difference in breeding seasonality.

Age Factors↗
PubMed2005

Serial electrophysiologic studies in rhesus monkeys with Krabbe disease.

Krabbe disease is a progressive leukodystrophy that results in demyelination in the central and peripheral nervous systems in humans. It has been described in a number of mammalian species including the rhesus monkey. We performed serial nerve conduction studies beginning within the first 2 months of life in four homozygous, two heterozygous, and two normal rhesus monkeys (Macaca mulatta) to characterize the peripheral neuropathy. Mean conduction velocities of the median, ulnar, and tibial nerves were significantly slower in the affected than unaffected monkeys at all ages (P < 0.0001). The conduction velocity differences became more apparent between the affected and unaffected as the monkeys aged. When compared to the unaffected monkeys, the serial conduction velocities suggested occurrence of dysmyelination followed by demyelination in the affected monkeys. These observations provide further insight into the disease process and suggest an early window of opportunity for treating Krabbe disease.

Action Potentials↗
PubMed2005

Predictive validity in a prospective follow-up of PTSD in preschool children.

OBJECTIVE: To examine the predictive validity of an alternative to the DSM-IV for diagnosing posttraumatic stress disorder (PTSD) in preschool children and prospectively explore the course of PTSD symptomatology. METHOD: Sixty-two traumatized children, ages 20 months through 6 years, were assessed three times in 2 years with caregiver diagnostic interviews. RESULTS: PTSD diagnosis at visit 1 significantly predicted degree of functional impairment 1 and 2 years later and predicted PTSD diagnosis 2 years later but not 1 year later. The lack of 1-year diagnostic continuity may be explained by children with new traumas. Unexpectedly, overall PTSD symptoms did not remit over time, regardless of community treatment; however, reexperiencing symptoms decreased and avoidance/numbing symptoms increased with time, with avoidance/numbing symptoms increasing at a faster rate in children with PTSD at visit 1. The previous finding that arousal may cause emotional numbing was not replicated. Significantly more children were functionally impaired at visits 2 (48.9%) and 3 (74.3%) than were diagnosed with PTSD (23.4% and 22.9%, respectively). CONCLUSIONS: This study demonstrates predictive validity for the alternative method of diagnosing PTSD in preschool children. The unremitting course of PTSD symptomatology in preschool children and rates of impairment that are higher than rates of diagnosis indicate the need for efficacious treatment.

Child Behavior Disorders↗
PubMed2005

Prevalence and clustering patterns of human papillomavirus genotypes in multiple infections.

Prevalence of multiple human papillomavirus (HPV) infections, involvement of specific HPV phylogenetic clades in multiple infections, and clustering patterns of multiple infections at the clade level were assessed in 854 HIV (-) and 275 HIV (+) women cross-sectionally. Reverse line blot assay was used to detect 27 HPV genotypes. Involvement of specific clades in coinfections and clustering patterns were assessed using HPV clade/genotype as the unit of analyses. Expected frequencies assuming independence for all possible clade combinations in two-genotype infections were derived using a multinomial expansion and comparisons of observed and expected frequencies were done using a composite goodness-of-fit test. In all, 100 two-genotype infections were detected; 61 in HIV (-) and 39 in HIV (+) women. Clade A9 (HPV types 16, 31, 33, 35, 52, and 58) was significantly less likely to be involved in multiple infections compared with all other clades (55.2% versus 64.6%; adjusted odds ratios, 0.68; 95% confidence interval, 0.48-0.95). Observed patterns for all possible clade combinations (among HPV clades A3, A5, A6, A7, A9, and A10) in two-genotype infections did not significantly differ from those expected in the entire sample, across HIV, Pap smear, and age strata (all goodness-of-fit exact P > 0.20). These results indicate that clade A9 is less likely to be involved in multiple infections and that HPV genotypes predominantly establish multiple infections at random, with little positive/negative clustering for either phylogenetically related or unrelated types. The current method of analysis affords the opportunity to test clustering of a large number of HPV genotype/clade combinations at nominal alpha levels.

Adult↗
PubMed2004

The effect of previous low back surgery on general health status: results from the National Spine Network initial visit survey of patients with low back pain.

STUDY DESIGN: A cross-sectional study on 18,325 patients with back pain enrolled at first visit in the National Spine Network (NSN) database from January 1998 to April 2000. OBJECTIVES: To examine whether patients who had previous low back surgeries had poorer general health status than patients with no surgery. SUMMARY OF BACKGROUND DATA: Several studies have described the role of psychological abnormalities in patients with chronic low back pain. Some of these patients have had previous spinal surgeries performed. No study has examined the effects of previous low back surgery on the general health status. METHODS: The Short Form Health Survey 36 was administered to the initial visit NSN patients. Of the 18,325 patients enrolled, 3,632 had previous low back surgeries. RESULTS: Patients who had previous lumbar surgeries fared significantly poorly in all 10 scores of the SF-36 health survey, even after adjustment for confounding factors. Among these patients, decompression achieved significantly higher scores for General Health, Role-Physical, and Mental Component Summary scales. Patients who had decompression as their most recent surgery had higher scores for General Health, Role-Physical, Role-Emotional, and Mental Component Summary scales, when compared to those who had other surgeries. Patients who had instrumentation as their most recent surgery had higher scores for Bodily Pain and Physical Component Summary scores. There is a positive correlation between time since last surgery and the SF-36 outcomes. CONCLUSIONS: Previous back surgery is associated with significantly worse general health status than those without surgery. Among patients who had previous surgeries, decompression seems to exert better effects on SF-36 health status. There is a positive correlation between time since last surgery and the SF-36 outcomes, although the SF-36 scores are significantly lower than those without previous surgery.

Adolescent↗
PubMed2004

Specific recruitment of regulatory T cells in ovarian carcinoma fosters immune privilege and predicts reduced survival.

Regulatory T (T(reg)) cells mediate homeostatic peripheral tolerance by suppressing autoreactive T cells. Failure of host antitumor immunity may be caused by exaggerated suppression of tumor-associated antigen-reactive lymphocytes mediated by T(reg) cells; however, definitive evidence that T(reg) cells have an immunopathological role in human cancer is lacking. Here we show, in detailed studies of CD4(+)CD25(+)FOXP3(+) T(reg) cells in 104 individuals affected with ovarian carcinoma, that human tumor T(reg) cells suppress tumor-specific T cell immunity and contribute to growth of human tumors in vivo. We also show that tumor T(reg) cells are associated with a high death hazard and reduced survival. Human T(reg) cells preferentially move to and accumulate in tumors and ascites, but rarely enter draining lymph nodes in later cancer stages. Tumor cells and microenvironmental macrophages produce the chemokine CCL22, which mediates trafficking of T(reg) cells to the tumor. This specific recruitment of T(reg) cells represents a mechanism by which tumors may foster immune privilege. Thus, blocking T(reg) cell migration or function may help to defeat human cancer.

Animals↗
PubMed2004

Heart period and variability findings in preschool children with posttraumatic stress symptoms.

BACKGROUND: Traumatic experiences for young children might result in profound neurodevelopmental changes, compared with adults. Our aim was to examine autonomic control of heart rate in traumatized young children. METHODS: Sixty-two children who had suffered traumas and 62 nontraumatized control children, aged 20 months to 6 years, were assessed for posttraumatic stress disorder (PTSD) symptoms, interbeat interval, respiratory sinus arrhythmia (RSA), family rehearsal of the trauma, and parent-child relationship quality. RESULTS: Traumatized children with PTSD and traumatized children without PTSD both had decreased heart period in response to a trauma stimulus relative to the nontraumatized group (both p < .0167). there was no main effect for RSA change scores, however, there was a significant interaction effect between parental positive discipline with PTSD symptoms and RSA. The most sympathetic children had decreased RSA during the trauma stimulus when they had caregivers with less positive discipline during a clean-up nd family rehearsal with PTSD symptoms. CONCLUSIONS: These findings underscore that psychopathology in young children ought to be assessed in the context of psychophysiology and parent-child relationship to optimally understand the mechanisms of maladaptation during this complex developmental period.

Adaptation, Psychological↗
PubMed2004

High-level penicillin-nonsusceptible Streptococcus pneumoniae bacteremia: identification of a low-risk subgroup.

High-level penicillin resistance has been associated with treatment failure in patients with Streptococcus pneumoniae infections. To identify a subgroup of patients at low risk for high-level penicillin-nonsusceptible S. pneumoniae bacteremia, a cross-sectional study of 303 patients was performed. For the total study population, penicillin resistance was observed in 98 (32%) of 303 patients; high-level resistance was seen in 33 (11%). A predictive model was created by using 3 baseline variables that were independently associated with high-level penicillin resistance: previous beta -lactam antibiotic use, previous stay in a risk area (defined as stay in day care facilities, prisons, homeless shelters, nursing homes, or other long-term care facilities), and previous respiratory tract infection. The model was used to identify patients at low and high risk for high-level penicillin-resistant pneumococcal bacteremia. None of the isolates of patients in the low-risk subgroup had ceftriaxone resistance. Patients in the low-risk subgroup could be empirically treated with fluoroquinolone-sparing regimens.

Adolescent↗
PubMed2004

Unnecessary cesarean delivery in Louisiana: an analysis of birth certificate data.

OBJECTIVE: The purpose of this study was to explore the temporal trends and factors that are associated with cesarean deliveries and potentially unnecessary cesarean deliveries. STUDY DESIGN: The Louisiana birth certificate database was evaluated to identify a total of 57 potential indications/risk factors and maternal demographic factors that are associated with methods of delivery over the period from January 1993 to December 2000. A cesarean delivery without any potential indications/risk factors in the birth certificate was classified as unnecessary. RESULTS: The primary cesarean delivery rate decreased and the repeat cesarean delivery rate increased significantly during the study period. But neither the absence nor the presence of potential indications/risk factors accounted for these changes. The average potentially unnecessary primary and repeat cesarean deliveries in Louisiana were 17 and 43, respectively, per 100 cesarean deliveries over the years 1993 through 2000. CONCLUSION: The proportions of potentially unnecessary cesarean deliveries are relatively high in Louisiana. It is important to explore the influence of nonclinical factors on unnecessary cesarean delivery to reduce the cesarean rates.

Birth Certificates↗
PubMed2004

Profiles of the adolescent smoker: models of tobacco use among 9th grade high school students: Acadiana Coalition of Teens against Tobacco (ACTT).

BACKGROUND: Tobacco use, underreported among Louisiana youth, was examined among 9th grade students in south central Louisiana; profiles of tobacco use were developed to inform adolescent tobacco control programs. METHODS: Cross-sectional Health Habits Survey was administered to 4,808 students who were about 15 years old, predominantly white, with gender almost evenly distributed. Saliva samples were collected from 1,966 students. Analysis of a subsample resulted in good concordance between self-reported daily tobacco use and cotinine. RESULTS: About 58% of students ever smoked a cigarette, 25% had a cigarette within the previous 30 days, 17% smoked within the past 7 days and almost 8% reported smokeless tobacco use. Smokeless tobacco use was greater for males than females. Caucasians, native Americans, and Latinos were more likely to smoke than African-Americans. Social relationships associated with adolescent smoking included having a friend, parent and/or sibling who smoked, having a friend who consumed alcohol, and being around people who used alcohol for "kicks." The attitudes of nonsmokers were consistently in the positive direction relative to disapproval of tobacco and alcohol use. The profiles differed demographically between black and white students. CONCLUSIONS: These data provide the needed information for guiding health promotion and tobacco control efforts, specifically regarding black/white differences.

Adolescent↗
PubMed2004

Estimating HIV incidence and detection rates from surveillance data.

BACKGROUND: Markov models that incorporate HIV test information can increase precision in estimates of new infections and permit the estimation of detection rates. The purpose of this study was to assess the functioning of a Markov model for estimating new HIV infections and HIV detection rates in Louisiana using surveillance data. METHODS: We expanded a discrete-time Markov model by accounting for the change in AIDS case definition made by the Centers for Disease Control and Prevention in 1993. The model was applied to quarterly HIV/AIDS surveillance data reported in Louisiana from 1981 to 1996 for various exposure and demographic subgroups. When modeling subgroups defined by exposure categories, we adjusted for the high proportion of missing exposure information among recent cases. We ascertained sensitivity to changes in various model assumptions. RESULTS: The model was able to produce results consistent with other sources of information in the state. Estimates of new infections indicated a transition of the HIV epidemic in Louisiana from (1) predominantly white men and men who have sex with men to (2) women, blacks, and high-risk heterosexuals. The model estimated that 61% of all HIV/AIDS cases were detected and reported by 1996, yet half of all HIV/non-AIDS cases were yet to be detected. Sensitivity analyses demonstrated that the model was robust to several uncertainties. CONCLUSIONS: In general, the methodology provided a useful and flexible alternative for estimating infection and detection trends using data from a U.S. surveillance program. Its use for estimating current infection will need further exploration to address assumptions related to newer treatments.

Female↗
PubMed2004

Relationship between the severity of penile curvature and the presence of comorbidities in men with Peyronie's disease.

PURPOSE: We investigated the relationship between penile curvature severity and co-morbidities in men with Peyronie's disease (PD) and assessed whether the severity of curvature had an impact on penile vascular status and/or erectile function. MATERIALS AND METHODS: Based on a 10-year period 469 patients with PD were retrospectively evaluated in regard to age at diagnosis, type and degree of penile curvature, erectile dysfunction (ED) and other comorbidities, such as diabetes mellitus, hypertension, serum lipid abnormalities, smoking and ischemic heart disease. To assess penile vascular status all men with PD underwent penile duplex Doppler ultrasound evaluation. The severity of penile curvature was classified using the Kelami system, that is grade 1--curvature 30 degrees or less, grade 2--30 to 60 degrees and grade 3--greater than 60 degrees. RESULTS: Mean patient age was 54.8 +/- 4.3 years (range 18 to 79) and the mean duration of symptoms was 24.8 +/- 13.7 months (range 3 to 120). The most common penile abnormality was dorsal curvature in 47.1% of patients. The most frequently documented co-morbid conditions in association with PD were hypertension in 27.2% of cases, smoking in 25.5%, hypercholesterolemia in 18.3%, diabetes mellitus in 17.2%, hyperlipidemia in 15.7% and a history of penile trauma in 13.2%. There was no relationship between the number or severity of each of these co-morbid conditions and the severity of the penile abnormality. In addition, there was no relationship between the severity of penile curvature and penile vascular status in patients with PD. Moreover, the prevalence of these comorbidities, except smoking and penile trauma history, was significantly higher in patients with PD and concurrent ED than in patients with PD only. CONCLUSIONS: While co-morbid conditions, such as hypertension, smoking, hypercholesterolemia, diabetes mellitus and hyperlipidemia, are commonly seen in patients with PD and may seem to be risk factors for PD, there was no statistical relationship between penile curvature severity and any of these comorbidities. Similarly there was no statistically significant relationship between the severity of curvature and penile vascular status or ED. The fact that the prevalence of associated comorbidities is higher in patients with PD and ED than in patients with PD only indicates that these comorbidities are more likely related to ED than to the pathogenesis of PD.

Adolescent↗
PubMed2004

A bayesian approach to parameter estimation for a crayfish (Procambarus spp.) bioaccumulation model.

Bioaccumulation models are used to describe chemical uptake and clearances by organisms. Averaged input parameter values are traditionally used and yield point estimates of model outputs. Hence, the uncertainty and variability of model predictions are ignored. Probabilistic modeling approaches, such as Monte Carlo simulation and the Bayesian method, have been recommended by the U.S. Environmental Protection Agency to provide a quantitative description of the degree of uncertainty and/or variability in risk estimates in ecological hazards and human health effects. In this study, a Bayesian analysis was conducted to account for the combined uncertainty and variability of model parameters in a crayfish bioaccumulation model. After a 5-d exposure in the LaBranche Wetlands (LA, USA), crayfish were analyzed for polycyclic aromatic hydrocarbon concentrations and lipid fractions. The posterior distribution of model parameters were derived from the joint posterior parameter distributions using a Markov chain Monte Carlo approach and the experimental data. The results were then used to predict the distribution of chrysene concentration versus time in the crayfish to compare the predicted ranges at the different study sites.

Animals↗
PubMed2004

Computing aspects of power for multiple regression.

Rules of thumb for power in multiple regression research abound. Most such rules dictate the necessary sample size, but they are based only upon the number of predictor variables, usually ignoring other critical factors necessary to compute power accurately. Other guides to power in multiple regression typically use approximate rather than precise equations for the underlying distribution; entail complex preparatory computations; require interpolation with tabular presentation formats; run only under software such as Mathmatica or SAS that may not be immediately available to the user; or are sold to the user as parts of power computation packages. In contrast, the program we offer herein is immediately downloadable at no charge, runs under Windows, is interactive, self-explanatory, flexible to fit the user's own regression problems, and is as accurate as single precision computation ordinarily permits.

Humans↗