THE RELATIONSHIP BETWEEN THE RHEOENCEPHALOGRAM AND CEREBRAL BLOOD FLOW

The rheoencephalogram (REG) is the change in the electrical impedance of the head that occurs with each heart beat. Without knowledge of the relationship between cerebral blood flow (Q) and the REG, the utility of the REG in the study of the cerebral vasculature is greatly limited. The hypothesis is that the relationship between the REG and Q when venous outflow is nonpulsatile is^ (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)^ where K is a proportionality constant and Q is the mean Q.^ Pulsatile CBF was measured in the goat via a chronically implanted electromagnetic flowmeter. Electrodes were implanted in the ipsilateral cerebral hemisphere, and the REG was measured with a two electrode impedance plethysmograph. Measurements were made with the animal's head elevated so that venous flow pulsations were not transmitted from the heart to the cerebral veins. Measurements were made under conditions of varied cerebrovascular resistance induced by altering blood CO(,2) levels and under conditions of high and low cerebrospinal fluid pressures. There was a high correlation (r = .922-.983) between the REG calculated from the hypothesized relationship and the measured REG under all conditions.^ Other investigators have proposed that the REG results from linear changes in blood resistivity proportional to blood velocity. There was little to no correlation between the measured REG and the flow velocity ( r = .022-.306). A linear combination of the flow velocity and the hypothesized relationship between the REG and Q did not predict the measured REG significantly better than the hypothesized relationship alone in 37 out of 50 experiments.^ Jacquy proposed an index (F) of cerebral blood flow calculated from amplitudes and latencies of the REG. The F index was highly correlated (r = .929) with measured cerebral blood flow under control and hypercapnic conditions, but was not as highly correlated under conditions of hypocapnia (r = .723) and arterial hypotension (r = .681).^ The results demonstrate that the REG is not determined by mean cerebral blood flow, but by the pulsatile flow only. Thus, the utility of the REG in the determination of mean cerebral blood flow is limited. ^

The relationship between the field-shifting phenomenon and representational coherence of place cells in CA1 and CA3 in a cue-altered environment.

Subfields of the hippocampus display differential dynamics in processing a spatial environment, especially when changes are introduced to the environment. Specifically, when familiar cues in the environment are spatially rearranged, place cells in the CA3 subfield tend to rotate with a particular set of cues (e.g., proximal cues), maintaining a coherent spatial representation. Place cells in CA1, in contrast, display discordant behaviors (e.g., rotating with different sets of cues or remapping) in the same condition. In addition, on average, CA3 place cells shift their firing locations (measured by the center of mass, or COM) backward over time when the animal encounters the changed environment for the first time, but not after that first experience. However, CA1 displays an opposite pattern, in which place cells exhibit the backward COM-shift only from the second day of experience, but not on the first day. Here, we examined the relationship between the environment-representing behavior (i.e., rotation vs. remapping) and the COM-shift of place fields in CA1 and CA3. Both in CA1 and CA3, the backward (as well as forward) COM-shift phenomena occurred regardless of the rotating versus remapping of the place cell. The differential, daily time course of the onset/offset of backward COM-shift in the cue-altered environment in CA1 and CA3 (on day 1 in CA1 and from day 2 onward in CA3) stems from different population dynamics between the subfields. The results suggest that heterogeneous, complex plasticity mechanisms underlie the environment-representating behavior (i.e., rotate/remap) and the COM-shifting behavior of the place cell.

The relationship between rheumatoid arthritis and reproductive function

There is growing support for the theory that an interaction between the immune and reproductive/endocrine systems underlies the pathogenesis of autoimmune rheumatic diseases. Most of the recent evidence derives from studies of sex hormones and pregnancy in women with systemic lupus. Other than an ameliorative effect of pregnancy, little is known about reproductive factors in relation to rheumatoid arthritis. To elucidate the relationship, a population-based retrospective study was undertaken. Included were 378 female residents of Olmsted County, Minnesota diagnosed with rheumatoid arthritis between 1950 and 1982 (cases) and 325 arthritis-free, married female controls matched to the 324 married cases on birth-year, age at first marriage, and duration of Olmsted County residency. Information of reproductive factors was extracted from the medical records system maintained by the Mayo Clinic.^ Cases had lower fertility rates compared with the female population of Minnesota (rate ratio = 0.86, 95% confidence interval (CI)= 0.80-0.92). Fertility was significantly reduced even prior to the onset of rheumatoid factor positive arthritis. Restricting the comparison to married Olmsted County residents did not alter the results. Further adjustments for time not at risk of conception using survival analysis and proportional hazards modeling only intensified the fertility reduction in the married cases compared with controls. Nulligravidity was more common among cases than controls (odds ratio = 3.16, CI = 1.61-6.20). Independent of fertility, pregnancy had a protective effect against rheumatoid arthritis (odds ratio = 0.31, CI = 0.11-0.89), which was dramatically reversed in the 12 months postpartum (odds ratio = 4.67, CI = 1.50-14.47). Cases were younger at menopause than controls (p $<$ 0.01).^ Small but statistically insignificant associations were observed between rheumatoid arthritis and the following factors: increased frequency of complaints to a physician of infertility; increased frequency of spontaneous abortion, premature birth, and congenital malformations following arthritis onset; and increased prevalence of menopause at arthritis onset. Cases did not differ from controls on age at menarche, duration of pregnancy, or birth weight.^ The findings provide further support for the involvement of the reproductive/endocrine systems in the pathogenesis of autoimmune rheumatic disease. The search for biological mechanisms should be intensified. ^

A study of the relationship between physical activity and cardiovascular fitness and coronary heart disease risk factors in female adolescents

The association of measures of physical activity with coronary heart disease (CHD) risk factors in children, especially those for atherosclerosis, is unknown. The purpose of this study was to determine the association of physical activity and cardiovascular fitness with blood lipids and lipoproteins in pre-adolescent and adolescent girls.^ The study population was comprised of 131 girls aged 9 to 16 years who participated in the Children's Nutrition Research Center's Adolescent Study. The dependent variables, blood lipids and lipoproteins, were measured by standard techniques. The independent variables were physical activity measured as the difference between total energy expenditure (TEE) and basal metabolic rate (BMR), and cardiovascular fitness, VO$\rm\sb{2max}$(ml/min/kg). TEE was measured by the doubly-labeled water (DLW) method, and BMR by whole-room calorimetry. Cardiovascular fitness, VO$\rm\sb{2max}$(ml/min/kg), was measured on a motorized treadmill. The potential confounding variables were sexual maturation (Tanner breast stage), ethnic group, body fat percent, and dietary variables. A systematic strategy for data analysis was used to isolate the effects of physical activity and cardiovascular fitness on blood lipids, beginning with assessment of confounding and interaction. Next, from regression models predicting each blood lipid and controlling for covariables, hypotheses were evaluated by the direction and value of the coefficients for physical activity and cardiovascular fitness.^ The main result was that cardiovascular fitness appeared to be more strongly associated with blood lipids than physical activity. An interaction between cardiovascular fitness and sexual maturation indicated that the effect of cardiovascular fitness on most blood lipids was dependent on the stage of sexual maturation.^ A difference of 760 kcal/d physical activity (which represents the difference between the 25th and 75th percentile of physical activity) was associated with negligible differences in blood lipids. In contrast, a difference in 10 ml/min/kg of VO$\rm\sb{2max}$ or cardiovascular fitness (which represents the difference between the 25th and 75th percentile in cardiovascular fitness) in the early stages of sexual maturation was associated with an average positive difference of 15 mg/100 ml ApoA-1 and 10 mg/100 ml HDL-C. ^

The relationship between leadership practices and a medication safety regime

Errors in healthcare are commonplace and have significant impact on mortality, morbidity, and costs. Other high-risk industries are credited with strong safety records. These successes are due in part to a strong, committed organizational culture and their leadership. A consistent pattern of effective leadership behaviors; creating change, establishing a vision and strategic actions, and enabling and inspiring the organization's members to act, is present in these high-risk industries. This research examined the relationship between leadership practices and a medication safety regime. The hypothesis is strong leadership practices have a positive relationship with the degree of sophistication of a medication safety program (safety performance). Leadership was used as a surrogate for organizational culture and was measured in this research through the Kouzes and Posner's Leadership Practices Inventory. The Institute of Medicine's 14 Selected Strategies to Improve Medication Safety was used to measure the development of a medication safety regime. Leadership practices towards safety were assessed by surveying 2,478 critical care Registered Nurses in the greater Houston area. A response rate of 19% was achieved. Thirteen hospitals participated in the medication safety regime assessment. Data from 386 RN respondents from 53 institutions provided an overall description of unit (ICU) and organization (hospital) leader's practices towards safety. There is some recognition of the medical error problem and that leaders exhibit moderate levels of leadership practices to promote safety. There were no differences noted in unit and hospital leaders' behaviors, with the exception that unit leaders promote change and enable staff to act more often than hospital leaders. There were no statistically significant relationships between overall leadership, or individual leadership practices and the organization's safety performance. There was a significant relationship between leadership and safety performance when other factors in organizational culture were considered. Teaching and Magnet hospitals also exhibited stronger behaviors towards safety. Organizational culture, as measured by academic affiliation and Magnet recognition, is strongly related to safety performance as measured by the degree of development of a medication safety regime. ^

Effect of maternal weight status on the relationship between prenatal smoking and infant birth weight

The purpose of this study was to assess the effect of maternal pre-pregnancy weight status on the relationship between prenatal smoking and infant birth weight (IBW). Prenatal cigarette smoking and maternal weight exert opposing effects on IBW; smoking decreases birth weight while maternal pre-pregnancy weight is positively correlated with birth weight. As such, mutual effect modification may be sufficiently significant to alter the independent effects of these two birth weight correlates. Finding of such an effect has implications of prenatal smoking cessation education. Perception of risk is an important determinant of smoking cessation, and reduced or low birth weight (LBW) as a smoking-associated risk predominates prenatal smoking counseling and education. In a population such as the US, where obesity is becoming epidemic, particularly among minority and low-income groups, perception of risk may be lowered should increased maternal size attenuate the effect of smoking. Previous studies have not found a significant interaction effect of prenatal smoking and maternal pre-pregnancy weight on IBW; however, use of self-reported smoking status may have biased findings. Reliability of self-reported smoking status reported in the literature is variable, with deception rates ranging from a low of 5% to as high as 16%. This study, using data from a prenatal smoking cessation project, in which smoking status was validated by saliva cotinine, was an opportunity to assess effect modification of smoking and maternal weight using biochemically determined smoking status in lieu of self report. Stratified by saliva cotinine, 151 women from a prenatal smoking cessation cohort, who were 18 years and older and had full-term, singleton births, were included in this study. The effect of smoking in terms of mean birth weight across three levels of maternal pre-pregnancy weight was assessed by general linear modeling procedures, adjusting for other known correlates of IBW. Effect modification was marginally significant, p = .104, but only with control for differential effects among racial/ethnic groups. A smaller than planned sample of nonsmokers, or women who quit smoking during the pregnancy, prohibited rejection of the null hypothesis of no difference in the effect of smoking across levels of pre-pregnancy weight. ^

The relationship between risk perception and ethnicity as an explanation for late stage skin cancer diagnosis in Black and Hispanic populations: An analysis using data from the 2005 Health Information and National Trends Survey

Objective. The purpose of this study was to determine the relationship between ethnicity and skin cancer risk perception while controlling for other risk factors: education, gender, age, access to healthcare, family history of skin cancer, fear, and worry. ^ Methods. This study utilized the Health Information National Trends Survey (HINTS) dataset, a nationally representative sample of 5,586 individuals 18 years of age or older. One third of the respondents were chosen at random and asked questions involving skin cancer. Analysis was based on questions that identified skin cancer risk perception, fear of finding skin cancer, and frequency of worry about skin cancer and a variety of sociodemographic factors. ^ Results. Ethnicity had a significant impact on risk perception scores while controlling for other risk factors. Other risk factors that also had a significant impact on risk perception scores included family history of skin cancer, age, and worry. ^

The relationship between oral contraceptives and pelvic inflammatory disease: Policy implications and recommendations

One of the most widely accepted noncontraceptive benefits of oral contraceptive use is the reduction in the development of pelvic inflammatory disease (PID) and its sequelae in users. While much of the research over the past forty years has found an association between oral contraceptive use and reduced rates of PID [Senanayake, 1980], more recent studies have qualified and even challenged this widely held belief. [Henry-Suchet, 1997; Ness 1997; Ness, 2001] PID, an infection in the upper genital tract causing infertility and ectopic pregnancy, affects over one million women in the United States each year, exacting an enormous toll on women's reproductive and emotional health, as well as our economy. [CDC Factsheet, 2007] This thesis examines the public health implications of pelvic inflammatory disease and the use of oral contraceptives. Sixteen original studies are reviewed and analyzed, thirteen of which found a protective benefit with oral contraceptive use against PID and three more recent studies which found no protective benefit or association between oral contraceptive use and PID. Analysis of the research findings suggests a need for additional research, provider and patient education, and an increased government role in addressing the ongoing and significant public health concerns raised by current rates of Chlamydia- and gonorrheal-PID. ^

The relationship between body image and physical activity in African American women

High rates of overweight and obesity in African American women have been attributed, in part, to poor health habits, such as physical inactivity, and cultural influences on body image perceptions. The purpose of this study was to determine the relationship among body mass index (BMI=kg/m2), body image perception (perceived and desired) and physical activity, both self-reported and objectively measured. Anthropometric measures of BMI and Pulvers' culturally relevant body image, physical activity and demographic data were collected from 249 African American women in Houston. Women ( M = 44.8 yrs, SD = 9.5) were educated (53% college graduates) and were overweight (M = 35.0 kg/m2, SD = 9.2). Less than half of women perceived their weight correctly regardless of their actual weight (p < 0.001). Nearly three-fourths (73.9%) of women who were normal weight desired to be obese, and only 39.4% of women desired to be normal weight, regardless of actual or perceived weight. Women in all weight classes (normal, overweight and obese) varied in objective measures of physical activity (F(2,112) = 4.424, p = .014). Regression analyses showed objectively measured physical activity was significantly associated with BMI ( Beta = -2.45, p < .01) and self-reported walking was significantly associated with perceived BMI (Beta = -.156, p = .017). Results suggest African American women who are smaller want to be larger and African American women who are larger want to be smaller, revealing dichotomous distortion in body images. Low rates of physical activity may be a factor. Research is needed to increase physical activity levels in African American women, leading to improved satisfaction with normal weight as desirable for health and beauty. Supported by NCI (NIH) 1R01CA109403. ^

The relationship between alcohol consumption and HDL cholesterol: A study of Hispanic drinking patterns

There has been very little research that has studied the effects of alcohol on biochemical markers in ethnic populations. This particular study is designed to identify the association, if any, between drinking patterns and high density lipoprotein cholesterol (HDL-C) levels in a Hispanic population. Most of what we know about the association between alcohol and HDL-C deals specifically with volume of alcohol consumed on a daily basis. Frequency, or how often alcohol consumption occurs within a given time period, is a variable that has rarely been studied. The results of this study showed how both volume and frequency of alcohol consumption affect HDL-C levels in a predominantly middle-aged Hispanic population. Ultimately, we will be able to apply these findings to future studies concerning risk of CHD in Hispanics. ^

The relationship between physical activity and perceived built environment factors among adult Mexican Americans living in Brownsville, Texas

Background. Physical Activity (PA) is a central part in the fight to reduce obesity rates that are higher in Mexican Americans in the United States than any other ethnic groups. More than half of all Americans do not meet the daily PA recommendations and 48% of Mexican Americans do not exercise. The built environment is believed to affect participation in physical activity. The influence of the built environmental on physical activity levels in low-income Mexican Americans living along the Texas-Mexico border has not been investigated. ^ Purpose. The purpose of this secondary data analysis was trifold: (1) to determine the levels of self-reported PA in adults living in Brownsville, Texas; (2) to characterize the perceptions of this population regarding the built environment; and (3) to determine the association between self-reported PA and the built environment in Mexican Americans living in Brownsville, Texas. ^ Methods. 400 participants from the Tu Salud ¡Sí Cuenta! (TSSC) community-wide campaign were included in this secondary data analysis. Percentages for level of physical activity and the built environment were calculated using SPSS. Perceptions of the built environment were assessed by 14 items. Logistic regression analysis was used to assess the relationship between physical activity and built environment. All models were adjusted for age, gender, and level of education. ^ Results. The majority of men (41.97%) and women (59%), combined (56.7%)did not meet the 2008 PA Guidelines for Americans. We analyzed 14 built environment variables to characterize participants’ perceptions of the built environment. We conducted odds ratio (OR) to find if those who met PA levels associated the built environment such as neighborhood shops ([OR:1.806], CI:1.074,3.038 ]) bus stops ([OR:1.436], CI:.806,2.558) unattended stray dogs ([OR: 1.806], CI:1. 074,3.038), sidewalk access ([OR: .858],CI:.437,1.686), access to free parks ([OR:.549],CI:.335,.900) heavy traffic in neighborhood ([OR:.802], CI:.501,1.285), crime rate ([OR:.779], CI:.494,1.228) ranked the highest by mean score. The association between physical activity and the perceived built environment factors for Mexican Americans participating in the TSSCStudy were weakly associated. ^ Conclusions. This study provides evidence that PA levels are low in this Mexican American population. The built environment factors assessed in this study characterized the need for further studies of the variables that are seen as important to the Mexican American population. Lastly, the association of PA levels to the built environment was weak overall and further studies are recommended of the built environment.^

THE RELATIONSHIP BETWEEN SERUM CHOLESTEROL AND CANCER INCIDENCE IN THE POPULATION OF THE HYPERTENSION DETECTION AND FOLLOW-UP PROGRAM

The relationship between serum cholesterol and cancer incidence was investigated in the population of the Hypertension Detection and Follow-up Program (HDFP). The HDFP was a multi-center trial designed to test the effectiveness of a stepped program of medication in reducing mortality associated with hypertension. Over 10,000 participants, ages 30-69, were followed with clinic and home visits for a minimum of five years. Cancer incidence was ascertained from existing study documents, which included hospitalization records, autopsy reports and death certificates. During the five years of follow-up, 286 new cancer cases were documented. The distribution of sites and total number of cases were similar to those predicted using rates from the Third National Cancer Survey. A non-fasting baseline serum cholesterol level was available for most participants. Age, sex, and race specific five-year cancer incidence rates were computed for each cholesterol quartile. Rates were also computed by smoking status, education status, and percent ideal weight quartiles. In addition, these and other factors were investigated with the use of the multiple logistic model.^ For all cancers combined, a significant inverse relationship existed between baseline serum cholesterol levels and cancer incidence. Previously documented associations between smoking, education and cancer were also demonstrated but did not account for the relationship between serum cholesterol and cancer. The relationship was more evident in males than females but this was felt to represent the different distribution of occurrence of specific cancer sites in the two sexes. The inverse relationship existed for all specific sites investigated (except breast) although a level of statistical significance was reached only for prostate carcinoma. Analyses after exclusion of cases diagnosed during the first two years of follow-up still yielded an inverse relationship. Life table analysis indicated that competing risks during the period of follow-up did not account for the existence of an inverse relationship. It is concluded that a weak inverse relationship does exist between serum cholesterol for many but not all cancer sites. This relationship is not due to confounding by other known cancer risk factors, competing risks or persons entering the study with undiagnosed cancer. Not enough information is available at the present time to determine whether this relationship is causal and further research is suggested. ^

A STUDY OF THE RELATIONSHIP BETWEEN SELF-ASSESSMENT AND CLINICAL EVALUATION OF HEARING STATUS

The relationship was explored between a subjective measure of hearing status, derived from a functional self-assessment expressed in terms of ability to hear and understand spoken words, and a comparable objective measure of hearing status, obtained from a speech reception test. The Augmentation Survey of the Health and Nutrition Examination Survey of the National Center for Health Statistics provided the necessary data for a sample of 3059 adults. Using chi-square tests for the subsample with the highest level of objectively assessed hearing status, favorable subjective assessments were found to be significantly associated with higher income, lower age group, higher level of educational attainment, greater psychological adjustment, fewer symptoms of depression, and higher self-ratings of overall health. In a linear regression with self-assessment of hearing status as the dependent variable, less than one-quarter of the variation could be explained by objective status and the six explanatory variables.^