Influenza seasonality: underlying causes and modeling theories.
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Humans↗
Biomedical subjects
E N Naumova
Publications and source records attributed to E N Naumova.
Leptin, body composition and bone mineral density in premenopausal women.
Body weight is known to be associated with bone mass, however, it is unclear whether body composition, as reflected by the percent of total weight that is fat tissue (%fat), is associated with bone mass independently of weight. Fat tissue is metabolically active, and hormonal factors may mediate an association of %fat with bone mass. Leptin, a hormone produced in fat tissue, has recently been shown to be inversely related to bone mass in mice, but whether it is related to human bone mass is uncertain. We sought to investigate the associations of %fat and of serum leptin concentration with bone mineral density (BMD) in a cohort of 153 premenopausal women. BMD measurements of the total hip, lumbar spine and total body as well as body composition were measured by dual energy X-ray absorptiometry (DXA). Serum leptin levels were established using a commercial competitive binding assay. Individually, body weight, %fat and leptin were each positively associated with BMD at all three sites. However, when we examined BMD either as a function of both body weight and %fat together, or as a function of both body weight and leptin together, we found that for a given body weight, BMD appeared to be inversely associated with %fat and similarly appeared to be inversely associated with leptin. When BMD was examined as a function of %fat and leptin together, we found that for a given %fat, leptin appeared to be inversely associated with BMD. In summary, the results of this study suggest that for a given body weight, a higher proportion of fat and a higher serum leptin concentration have negative associations with bone mass in premenopausal women.
Absorptiometry, Photon↗
Recall of early menstrual history and menarcheal body size: after 30 years, how well do women remember?
The validity of recall of early menstrual characteristics is of interest because of their putative role in the etiology of breast cancer and other diseases. A retrospective follow-up of the Newton Girls Study (1965-1975) provided an opportunity to assess the accuracy and precision of recall of several early menstrual characteristics. In 1998-1999, 57 percent of the original 793 Newton Girls Study participants completed a mailed questionnaire to assess the accuracy of recall for age and body size at menarche, usual cycle length during the first 2 years, and age at regularity. Recalled and original age at menarche were highly correlated (r = 0.79, p < 0.001). The body mass index percentile at menarche was well correlated with recalled body size at menarche (r = 0.61, p < 0.001), but with some evidence of systematic bias. Overall, a woman's recall of menarcheal age and body size was better than recall of cycle length and occurrence of regularity. The failure to identify certain menstrual characteristics as exposures for subsequent disease may reflect limitations in the accuracy and precision of the recalled measures.
Adult↗
Expert opinion on body mass index percentiles for figure drawings at menarche.
We contacted clinicians and researchers who work in the area of childhood obesity to obtain a reasonable estimate of body mass index (BMI) percentile at menarche associated with a series of widely used figure drawings. Forty of 108 subscribers to the electronic listserv of the Pediatric Obesity Interest Group of the North American Association for the Study of Obesity responded to a request to estimate the BMI percentile at menarche for each of seven drawings. Median BMI percentile values ranged from three to 98 and means from 4.0 to 97.6, with the greatest agreement at the high end and the poorest agreement in the central part of the range. This approach may be useful in situations where weight and height are not readily recalled.
Body Mass Index↗
Tutorial in Biostatistics: Evaluating the impact of 'critical periods' in longitudinal studies of growth using piecewise mixed effects models.
Recent developments in modern multivariate methods provide applied researchers with the means to address many important research questions that arise in studies with repeated measures data collected on individuals over time. One such area of applied research is focused on studying change associated with some event or critical period in human development. This tutorial deals with the use of the general linear mixed model for regression analysis of correlated data with a two-piece linear function of time corresponding to the pre- and post-event trends. The model assumes a continuous outcome is linearly related to a set of explanatory variables, but allows for the trend after the event to be different from the trend before it. This task can be accomplished using a piecewise linear random effects model for longitudinal data where the response depends upon time of the event. A detailed example that examines the influence of menarche on changes in body fat accretion will be presented using data from a prospective study of 162 girls measured annually from approximately age 10 until 4 years post menarche.
Adipose Tissue↗
Possible undetected outbreaks of cryptosporidiosis in areas of the north west of England supplied by an unfiltered surface water source.
We report a ten-year retrospective analysis of laboratory reports of cryptosporidium infection in the North West of England. Weekly report data from six health authorities known to have been affected by outbreaks associated with a single supply were compared with data from other health authorities in the North West. Following graphical representation of report rates, it would appear that outbreaks in the six health authorities were considerably more common than the average recorded in the national outbreak surveillance system.
Animals↗
Survival and failure to thrive in the SIV-infected juvenile rhesus monkey.
In AIDS patients, wasting in adults and failure to thrive in children are common and devastating problems. Weight loss in rhesus macaques infected with simian immunodeficiency virus (SIV) has not been well characterized. The purpose of this study was to determine growth curves in SIV-infected juvenile macaques to determine the effects of SIV infection on body weight and growth. Medical records of seven juvenile male SIV-infected macaques were retrospectively reviewed to determine body weights, survival time, CD4 count, and viral load. Mean age and body weight at the time of inoculation were 63.3 weeks and 2.4 kg, respectively. Mean survival was 73.7 weeks, and mean body weight at the time of death was 3.0 kg, whereas the published mean body weight for this age of male rhesus macaque is 4.1 kg. Compared with the linear growth pattern of normal animals, the growth pattern for the SIV-infected animals exhibited strong nonlinearity with an inflection point at the mean survival of 74 weeks. After this time point, the discrepancy between growth curves for infected and healthy animals increased at a greater rate. Body weight correlated inversely with viral load (r = -0.368; p = .003) but there was no correlation between body weight and CD4 count. The results of this study suggest that failure to thrive is a consequence of SIV infection and may be related to severity of infection.
Animals↗
A class I MHC-restricted recall response to a viral peptide is highly polyclonal despite stringent CDR3 selection: implications for establishing memory T cell repertoires in "real-world" conditions.
In this study, we analyze the recall response to influenza A matrix peptide M1(58-66) restricted by HLA-A2 in one individual and find a strict CDR3 selection as well as a high degree of polyclonality. The TCR beta-chain repertoire of memory T cells specific for this Ag system has been shown previously to be constrained by the use of the BV17 family and the I/sRS(A)/S amino acid motif in the CDR3 region. Our sequence analysis of BV17 TCR from a CTL line showed the repertoire to be highly polyclonal, as 95 distinct CDR3 sequences (clonotypes) were identified expressing this CDR3 motif. The clonotype frequencies showed a power law distribution with an extensive low-frequency tail. The clonotypes present in the high-frequency component of the distribution could be measured directly in the PBMC. This measurement showed that the relative frequencies of these clonotypes before stimulation were similar to their frequencies after culturing. Analysis of short-term cultures showed that the responding clonotypes have a similar ability to proliferate, which is independent of TCR beta-chain CDR3 sequence or precursor frequency. These data indicate that the memory T cell repertoire is composed of a surprisingly diverse set of T cell clonotypes with a limited potential for expansion. We propose that the high-frequency component represents T cells that have existed the longest. In keeping with this hypothesis, these clonotypes were measured over a 2-year period, during which their precursor frequency did not change.
Hematopoietic Stem Cells↗
Presence of HSV-1 DNA in semen and menstrual blood.
Using a specifically designed diagnostic PCR assay with nested primers the following could be achieved: (1) a group of 22 clinically indistinguishable women attending an infertility clinic, 18 with repeated embryo transfer failure, and asymptomatic for HSV-1 could be divided into two subgroups after testing their menstrual blood. An HSV-DNA positive (50%) and HSV-DNA negative group (50%) could be distinguished. None of the four controls were positive; (2) semen from 154 infertile and 24 fertile men was tested in relation to infertility. In the group of infertile men 37 (24%) were HSV-DNA positive but none of the fertile control (0%) was positive; (3) treatment of both partners with an antiviral drug resulted in two pregnancies; (4) HLA data on four of the couples in which the wife's menstrual blood was HSV positive was compared to seven HSV negative couples and 22 infertile, as well as 22 fertile couples. Clustering of class I HLA (B61 and Cw3) was found with a significant increase in Cw3 in both partners.
Adult↗
Carbon monoxide and hospital admissions for congestive heart failure: evidence of an increased effect at low temperatures.
The combined effects of carbon monoxide and low temperature on daily variation in hospital admissions for congestive heart failure (CHF) were examined for a 4-year period in Chicago, Illinois. Medicare hospital admissions for CHF were analyzed as a function of the maximum hourly temperature, maximum hourly levels of carbon monoxide (CO), and other criteria pollutants in Chicago for each day of the 4-year period (1986-1989). The regression analyses for the time series were conducted using single and multipollutant models with interaction terms and adjustments for weather, weekly cycles, seasonal effects, and secular trend. The data were also grouped into three temperature ranges, <40 degrees, 40 degrees-75 degrees, and >75 degrees F, and the relationship between CO and CHF admissions was evaluated for each range. For the 4-year time series, the CO level was positively associated with hospital admissions for CHF in the single pollutant and multipollutant models after adjustment for seasonal effects and weather pattern. The relative risks of hospital admissions for CHF in Chicago associated with the 75th percentile of exposure to CO in the high, medium, and low temperature ranges were 1.02 [95% confidence interval (CI), 0.95-1.10], 1.09 (CI, 1.04-1.14), and 1.15 (CI, 1.09-1.22), respectively. In these data, the effect of CO on hospital admissions for CHF was temperature dependent, with the magnitude of the effect increasing with decreasing temperature. This synergy may help to explain the association between ambient CO and CHF admissions demonstrated in other studies.
Air Pollutants↗
Did Milwaukee experience waterborne cryptosporidiosis before the large documented outbreak in 1993?
The patterns of incidence and pathways of spread for cryptosporidiosis are poorly understood. In this study, we explored the possibility that drinking water caused significant waterborne cryptosporidiosis in Milwaukee well before the massive documented outbreak in April 1993. We generated time series of daily counts of emergency room visits and hospital admissions for gastroenteritis in Milwaukee using the billing records of the Medical College of Wisconsin for January 1, 1992, through May 3, 1993. The Milwaukee Water Works provided us with data on drinking water turbidity for the same period. The service area of the South Plant experienced a sharp rise in turbidity just before the outbreak. During the outbreak period, gastroenteritis events were most strongly associated with turbidity at a lag of 7 days in children and 8 days in adults. It is reasonable to conclude that these lag times reflect the incubation period of Cryptosporidium. During the 434 days before the outbreak, gastroenteritis events were most strongly associated with turbidity at a lag of 8 days among children and 9 days among adults in the service area of the North Plant, the plant that experienced the highest effluent turbidity during this period. These findings are consistent with the conclusion that waterborne cryptosporidiosis was occurring in Milwaukee for more than a year before the documented outbreak.
Adult↗
Detection of herpes simplex DNA in semen and menstrual blood of individuals attending an infertility clinic.
OBJECTIVE: To determine a possible link between herpes simplex virus 1 (HSV) and infertility. METHOD: A specifically designed polymerase chain reaction with nested primers, was developed and used to test for HSV in 153 men and 20 women attending an infertility clinic. RESULTS: HSV DNA was detected in 37 (24%) out of 153 semen samples and in 11 (55%) out of 20 menstrual blood samples. However, HSV DNA (0%) was not detected in the semen of 16 males with children. A significant association between the evidence for infertility and an HSV positive test was observed in men (Fisher's exact test, p = 0.024), and a stronger effect was found in females after failed in vitro fertilization (Fisher's exact test p = 0.0086). CONCLUSION: This is the first report of the detection of herpes simplex virus DNA in semen and menstrual blood. Encouraging preliminary results justify antiviral therapy in case of a positive test.
Acyclovir↗
Temporal variation in drinking water turbidity and diagnosed gastroenteritis in Milwaukee.
Daily counts of diagnosed gastroenteritis (gastrointestinal events) in Milwaukee County, Wisconsin, from January 1992 through April 1993 were compared with reported daily turbidity from the two drinking water treatment plants serving the county. Turbidity in both plants was associated with an increased number of gastrointestinal events even after exclusion of a major documented outbreak of cryptosporidiosis. During the 434-day period prior to the outbreak, an increase in turbidity of 0.5 nephelometric turbidity units at one of the plants was associated with relative risks for gastrointestinal events of 2.35 among children (95% confidence interval [CI] = 1.34, 4.12) and 1.17 among adults (95% CI = 0.91, 1.52).
Adolescent↗
Ambient air pollution and hospitalization for congestive heart failure among elderly people in seven large US cities.
OBJECTIVES: Preexisting data sets were used to investigate the association between hospital admissions for congestive heart failure and air pollutants. METHODS: Medicare hospital admissions data, ambient air pollution monitoring data, and meteorological data were used to create daily values of hospital admissions for congestive heart failure, maximum hourly temperature, and maximum hourly levels of carbon monoxide, nitrogen dioxide, sulfur dioxide, and ozone. Data were compiled for each of seven cities (Chicago, Detroit, Houston, Los Angeles, Milwaukee, New York, and Philadelphia) for 1986 through 1989. Single-pollutant and multipollutant models with adjustments for temperature, seasonal effects, and weekly cycles were used in conducting negative binomial regression analyses. RESULTS: Ambient carbon monoxide levels were positively associated with hospital admissions for congestive heart failure in the single-pollutant and multipollutant models for each of the seven cities. The relative risk of hospital admission for congestive heart failure associated with an increase of 10 ppm in carbon monoxide ranged from 1.10 in New York to 1.37 in Los Angeles. CONCLUSIONS: Hospital admissions for congestive heart failure exhibited a consistent association with daily variations in ambient carbon monoxide. This association was independent of season, temperature, and other major gaseous pollutants.
Age Distribution↗
CD4+ and CD8+ circulating alpha/beta T-cell repertoires are equally complex and are characterized by different levels of steady-state TCR expression.
The repertoire complexity of CD4+ and CD8+ T cells was measured in three healthy blood donors for a number of TCR BV gene families by TCR spectratyping. This method subdivides V family-specific PCR products based on CDR3 length. Genomic DNA was analyzed to determine the distribution of the cells bearing particular V-J rearrangements. cDNA was analyzed to measure the levels of transcripts arising from those same cells. The complexity and distribution of T cells in each lineage were equal for most BV families. Certain families showed frequent skewing in CD8 cells. Analysis of the intensity profiles of RNA versus DNA spectratypes indicated that in general, there is a constant ratio of transcript per cell for all rearranged sizes within a particular family. This ratio appeared higher in CD4 cells. Thus, steady state levels of TCR mRNA were measured and found to be higher in CD4+ than in CD8+ cells.
CD4-Positive T-Lymphocytes↗
Use of passive surveillance data to study temporal and spatial variation in the incidence of giardiasis and cryptosporidiosis.
OBJECTIVE: The goal of this study was to evaluate temporal and spatial variations in the reporting of cases of giardiasis and cryptosporidiosis to a passive surveillance system, and to assess the relationship of those variations to source of drinking water, adjusting for socioeconomic variables. METHODS: The authors analyzed temporal and spatial patterns for 4,058 cases of giardiasis and 230 cases of cryptosporidiosis reported to the Massachusetts Department of Public Health for 1993-1996. They linked each reported case to a database containing information on source of residential water supply and socioeconomic characteristics and evaluated the association between these factors and reporting rates using regression techniques. RESULTS: Reports of giardiasis and cryptosporidiosis were highest for the mixed unfiltered drinking water supply category. Reports of giardiasis were associated with income levels. Increases in reporting for both giardiasis and cryptosporidiosis were seen in summer to early fall. During a suspected outbreak of cryptosporidiosis n the city of Worcester in 1995, a significant increase in reported cases was also observed in the Boston metropolitan area. Following the suspected outbreak, weekly giardiasis rates increased slightly in Worcester and the Boston metropolitan area, while reporting of cryptosporidiosis increased dramatically. CONCLUSIONS: Consistently collected passive surveillance data have the potential to provide valuable information on the temporal variation of disease incidence as well as geographic factors. However, passive surveillance data, particularly in the initial period of surveillance, may be highly sensitive to patterns of diagnosis and reporting and should be interpreted with caution.
Adolescent↗
Childhood asthma surveillance using computerized billing records: a pilot study.
OBJECTIVE: This paper describes a pilot project to develop and implement a low-cost system for ongoing surveillance of childhood asthma in Milwaukee County, Wisconsin. METHODS: The authors organized a planning workshop to solicit information and ideas for an asthma surveillance system, bringing together national experts with Milwaukee professionals and community representatives involved in the prevention and treatment of asthma. Based on recommendations from the workshop, a pilot surveillance project was implemented in Milwaukee County using records of emergency room visits and hospital admissions for asthma abstracted from the computerized billing records of the Children's Hospital of Wisconsin (CHW), retrospectively for 1993 and prospectively for 1994. Retrospective data were also sought from the other hospital emergency departments in Milwaukee County to evaluate the representativeness of the CHW data. Surveillance data were used to evaluate utilization of care by patient subgroups and to describe temporal patterns in emergency room visits. RESULTS: Of the emergency department visits for asthma in Milwaukee County in 1993, CHW accounted for 94% among infants less than 1 year of age, 89% among children ages 1 through 5 years, and only 59% among children between the ages of 6 and 18 years. In 1994, the 7% of asthmatic children with repeat hospital admissions accounted for 38% of all hospital admissions for asthma and the 20% with repeat emergency department visits accounted for 50% of all emergency visits. Emergency visits for asthma showed clear seasonality, with a peak in the fall and a smaller peak in the spring. CONCLUSIONS: Computerized medical billing data provide an opportunity for asthma surveillance at a relatively low cost. The data obtained are useful for tracking trends in exacerbations of asthma and the use of medical services for asthma care and should prove valuable in targeting interventions.
Adolescent↗
[Effect of population density on ecological characteristics of the grass moth Loxostege sticticalis L. (Lepidoptera: Pyralidae) in the gradation cycle].
We continued to study the diversity of responses of the grass moth Loxostege sticticalis L. to variations of density. We estimated the dynamics of the internal state of individuals and considered the influence of the population prehistory on ecological characteristics of the phytophage. In experiments on studying the structure of flower forms of the larval stage, we showed the dependence of the parameters of the internal state of individuals on prehistory, specifically on the conditions of life and type of individuals of the preceding generation. At the same time, comparison of the experimental results of 1991 and 1994 revealed a drift of the parameters of the reaction to variations in the grass moth population density by the structure of the larval flower forms and actual fertility of the imago. On the whole, the data obtained suggests that the studied species is characterized by a complex system of endogenous mechanisms underlying the regulation of numbers. The dynamics of environmental parameters is mediated by a cascade of endogenous rearrangements, as a result of which transition from depression to mass reproduction is realized through succession of the types of individuals in the population, when instead of a single phase, the flock phase starts to dominate.
Animals↗