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Biomedical subjects

C L Arfken

Publications and source records attributed to C L Arfken.

16 recordsLinked to original sources
PubMed1996

5-Hydroxytryptamine4 receptors reduce afterhyperpolarization in hippocampus by inhibiting calcium-induced calcium release.

Serotonin acting on 5-hydroxytryptamine4 receptors increases membrane excitability in CA1 hippocampal pyramidal cells by reducing the slow calcium-activated afterhyperpolarization. This effect is mediated through an increase in cAMP and activation of protein kinase A, although subsequent steps have not been elucidated. We now report that a significant portion of the calcium responsible for the generation of the afterhyperpolarization originates from the release of intracellular calcium through a calcium-induced calcium-release mechanism. Thus, the afterhyperpolarization is enhanced by caffeine, whereas it is inhibited by dantrolene and ruthenium red, two blockers of calcium-induced calcium release. The afterhyperpolarization is also inhibited by thapsigargin, which depletes intracellular calcium stores. These observations raised the possibility that serotonin might reduce the afterhyperpolarization by regulating calcium-induced calcium release. Consistent with this possibility, administration of calcium-induced calcium-release blockers, as well as of thapsigargin, occluded the ability of serotonin to inhibit the afterhyperpolarization. Similarly, administration of caffeine, which enhances the contribution of calcium-induced calcium release to the afterhyperpolarization, enhanced the effect of serotonin. These results indicate that serotonin inhibits the afterhyperpolarization in the CA1 region of hippocampus by reducing the ability of extracellular calcium to trigger calcium release from intracellular stores. As such, they identify a physiological role for the calcium-induced calcium release in hippocampus and provide evidence for its regulation by G protein-coupled receptors and, more specifically, 5-hydroxytryptamine4 receptors.

Action Potentials↗
PubMed1994

Retinopathy in African Americans and whites with insulin-dependent diabetes mellitus.

BACKGROUND: The development and progression of diabetic retinopathy in African Americans with insulin-dependent diabetes mellitus is not known. METHODS: Two hundred subjects with insulin-dependent diabetes mellitus with duration of diabetes 16 years or less at first visit were studied; 58 were African Americans and 142 were whites. All had gradable stereoscopic color fundus photographs (seven standard fields) from at least two visits (mean time between first and second visit was 4.1 years). Subjects with hemoglobinopathy or proliferative retinopathy or subjects who had evidence of treatment for proliferative retinopathy at first visit were excluded. Masked grading of photographs was conducted using the modified Airlie House classification scheme. RESULTS: African Americans were older, heavier, had higher systolic blood pressure (all P < .05), and marginally higher hemoglobin A1 (HbA1) values (P = .06) than the whites at first visit. African Americans had a lower rate of two steps or more progression from preexistent retinopathy (19%) than whites (43%). Progression to proliferative retinopathy or treatment was similar by race. Multivariate analysis predicting development oe progression of retinopathy, while controlling for length of follow-up, found higher HbA1 (odds ratio [OR] = 2.15), longer duration of insulin-dependent diabetes mellitus (OR = 1.69), higher serum creatinine concentration (OR = 1.59), and white race (OR = 2.62) to be independent risk factors. CONCLUSIONS: These data suggest a previously unsuspected reduction in the adjusted risk for development and progression of retinopathy in African Americans. The reason for this apparently reduced risk are not known.

Adolescent↗
PubMed1994

The prevalence and correlates of fear of falling in elderly persons living in the community.

OBJECTIVES: Fear of falling has been recognized as a potentially debilitating consequence of falling in elderly persons. However, the prevalence and the correlates of this fear are unknown. METHODS: Prevalence of fear of falling was calculated from the 1-year follow-up of an age- and gender-stratified random sample of community-dwelling elderly persons. Cross-sectional associations of fear of falling with quality of life, frailty, and falling were assessed. RESULTS: The prevalence of fear increased with age and was greater in women. After adjustment for age and gender, being moderately fearful of falling was associated with decreased satisfaction with life, increased frailty and depressed mood, and recent experience with falls. Being very fearful of falling was associated with all of the above plus decreased mobility and social activities. CONCLUSIONS: Fear of falling is common in elderly persons and is associated with decreased quality of life, increased frailty, and recent experience with falls.

Accidental Falls↗
PubMed1994

Factors responsible for impaired fibrinolysis in obese subjects and NIDDM patients.

Accelerated atherosclerosis is the leading cause of death in patients with non-insulin-dependent diabetes mellitus (NIDDM). Impaired endogenous fibrinolytic activity may accelerate atherosclerosis by exposing vascular luminal wall surfaces to persistent and recurrent thrombi and clot-associated mitogens. This study was conducted to further characterize endogenous fibrinolysis in lean and obese nondiabetic subjects and in NIDDM patients and to identify mechanisms responsible for the alterations identified. Obese and diabetic subjects had threefold elevations of plasma concentrations of plasminogen activator inhibitor type 1 (PAI-1) compared with values in lean control subjects. Despite the lack of significant differences in plasma concentrations of tissue-type plasminogen activator in the obese and diabetic subjects, both basal and stimulated endogenous fibrinolytic activities were decreased. The decreases were associated with increased activity of PAI-1 in plasma, in turn correlated with increased concentrations of immunoreactive insulin and C-peptide. These results are consistent with our previous observations demonstrating direct stimulatory effects of insulin and its precursors on cellular expression of PAI-1 in vitro and observations by others demonstrating decreased basal fibrinolytic activity in NIDDM patients. Impaired endogenous fibrinolytic activity could lead to prolonged or recurrent exposure of luminal surfaces of vessel walls to microthrombi and clot-associated mitogens that may accelerate atherosclerosis in hyperinsulinemic subjects.

Adult↗
PubMed1993

Mitral valve prolapse and body habitus in children.

Mitral valve prolapse has generally been associated in adults with a thin body habitus. However, prior studies used biased samples or limited anthropometric measures. In addition, no information has been available on the subjective assessment of body habitus and diagnosis of mitral valve prolapse, especially in children. We conducted a cross-sectional study on 813 children with uniform assessment of anthropometric measures and mitral valve prolapse. Consistent with research conducted on adults, those subjects with mitral valve prolapse were lighter, thinner, and had, on average, lower values for several, quantifiable anthropometric parameters with the exception of height. However, the subjective assessment showed that while the assessment did not differ by diagnosis, those subjects with mitral valve prolapse were never described as fat. These data support an association between mitral valve prolapse and slender body habitus and extends it to children, thus underscoring the clinical importance that a thin body habitus may be a marker for mitral valve prolapse throughout the age span. This association may partly explain the observed genetic distribution of mitral valve prolapse.

Body Constitution↗
PubMed1993

Frailty and injuries in later life: the FICSIT trials.

Physical frailty and fall-related injuries present two of the biggest threats to older people's functioning and quality of life. The Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT) trials represent a set of eight different clinical trials concerning physical frailty and injuries in later life. This report documents the history and organization of the trials and provides an overview of the measures being collected at multiple sites and the analytic strategies to be used for multi-site investigations.

Accidental Falls↗
PubMed1993

Clock completion: an objective screening test for dementia.

OBJECTIVE: To develop a simple, readily administered and scored screening test for dementia utilizing the clock-drawing task. DESIGN: Retrospective analysis of clock-drawing errors and prospective validations. SETTING: Hospital-based outpatient geriatric assessment clinic, rehabilitation service, apartment building for older adults, and long-term care facility. PARTICIPANTS: Convenience sample of patients attending the geriatric assessment clinic, patients on the rehabilitation service, or residents of the above sites. MEASUREMENTS: Sensitivity and specificity of a clock-scoring system in identifying patients with dementia and the comparison of this system with the Short Blessed Test (SBT) in the diagnosis of dementia and in the prospective validation of the test. RESULTS: Of the 10 clock-drawing errors evaluated, placement of digits in a pre-drawn circle had the greatest sensitivity and specificity in distinguishing patients with irreversible dementia from patients with other disorders who did not meet NINCDS-ADRDA criteria for probable dementia. The derived scoring system had a sensitivity of 87% and a specificity of 82%, compared with a sensitivity of 82% and a specificity of 88% for the SBT in identifying dementia. Test-retest reliability for the distinction between demented and non-demented was 82%, with a Kappa of 0.63 for the clock completion, and 82%, with a Kappa of 0.62 for the SBT. Inter-rater reliability for clock completion was 0.90 to 0.93. CONCLUSION: A simple, completely objective scoring system for a clock completion test has been developed which involves only the number of digits placed in the fourth quadrant of a pre-drawn circle. This readily administered test is as effective in screening for dementia as the longer six-item SBT.

Aged↗
PubMed1992

Meta-analysis of second malignant tumors in head and neck cancer: the case for an endoscopic screening protocol.

A meta-analysis was performed on data from the Washington University Department of Otolaryngology Head and Neck Tumor Registry and 24 studies reporting synchronous and metachronous malignancies in head and neck cancer patients. The overall second malignant tumor (second primary) prevalence was 14.2% in 40,287 patients, the majority of tumors being metachronous. Site relationships between index tumors and second primaries revealed significantly high risks along the digestive tract axis or the respiratory tract axis, although lung second primaries were prevalent in all groups. Head and neck second primaries were the largest group, being significantly more common in the oral cavity, oropharynx, and hypopharynx than in the larynx. Oral cavity index tumors showed the highest overall rate of second primary formation. Half of all aerodigestive tract second primaries are detected by 2 years from index tumor presentation, but non-aerodigestive tract tumors are common beyond 5 years. A significantly higher detection rate was proven for the prospective panendoscopy studies. We recommend routine interval endoscopic intervention within 2 years of treatment for optimum detection of second primaries in head and neck cancer patients. Also, a lifetime of clinical surveillance is suggested for aerodigestive tract second neoplasms in oral cavity, oropharynx, and hypopharynx cancer patients and for lung and non-aerodigestive tract neoplasms in larynx cancer patients.

Humans↗
PubMed1992

Compliance with dietary prescriptions in children and adolescents with insulin-dependent diabetes mellitus.

This study investigated the relationship between compliance with a prescribed diabetic diet and metabolic control of insulin-dependent diabetes mellitus (IDDM). The study sought to determine the degree to which patients translated food exchange prescriptions into appropriate food choices and to identify correlations between metabolic control (as measured by glycosylated hemoglobin level) and compliance with prescribed food exchanges, body mass index (BMI), and intake of energy and fat. Subjects were 40 inpatients and 29 outpatients aged 4 to 18 years with IDDM. Records of the inpatients' food selections for 3 days and 3-day food records collected from the outpatients (or their parents) were analyzed. For all 69 subjects, the mean daily deviation from the prescribed food exchanges was 23.8%, which indicates that subjects added or deleted approximately one of four prescribed exchanges. Records of actual food intake revealed that both patient groups had greater mean energy intakes than had been prescribed: 196 additional kcal for inpatients and 372 additional kcal for outpatients; fat sources accounted for 92% and 68% of the greater energy intake, respectively. No correlation was found between glycosylated hemoglobin level and BMI, energy intake, or fat intake.

Adolescent↗
PubMed1991

Medications and multiple falls in elderly people: the St Louis OASIS study.

The purpose of this study was to identify associations between the use of commonly taken medications and groups of medications and the risk of falls in elderly people living in the community. A stratified random sample of 1358 persons aged 65 years and over was selected from the 15,000 members of an educational organization for functionally independent, community-dwelling elderly people in St Louis, Missouri. Twenty-seven per cent of subjects reported at least one fall in the past year and 8% reported two or more falls. After adjusting for potential confounders (including age, sex, relevant medical conditions, health status, cognitive impairment, use of alcohol, depression and use of other medications), the following medications were found to be important risk factors for multiple falls: diazepam [odds ratio (OR): 3.7, 95% confidence interval (CI): 1.5-9.3], diltiazem (OR: 1.8, 95% CI: 0.8-4.1), diuretics (OR: 1.8, 95% CI: 1.2-2.8) and laxatives (OR: 2.1, 95% CI: 1.0-4.5). We conclude that caution is needed before prescribing diuretics and psychotropics, especially diazepam, for elderly people. The safety of diltiazem in this age group should be assessed further.

Accidental Falls↗
PubMed1991

Falls in the elderly: reliability of a classification system.

To determine risk factors for falls, previous studies have classified falls according to the contribution of factors both intrinsic and extrinsic to the host. Due partly to the lack of operational definitions and the absence of information on reliability, no consensus on classification has been reached. Consequently, in a 3-year prospective study of falls occurring in a probability sample of community-dwelling elderly (n = 1,358), a fall classification system was developed and tested for interrater reliability. The 366 falls in the first year of the study were independently classified by two reviewers on the basis of a narrative description and structured interview. The falls in the four major categories of the classification system included: falls related to extrinsic factors (55%), falls related to intrinsic factors (39%), falls from a non-bipedal stance (8%) and unclassified falls (7%). The interrater reliability for the four major categories was 89.9% with a kappa of 0.828. The system provides operational definitions for types of falls and a reliable and flexible method for classifying falls in the elderly.

Accidental Falls↗
PubMed1990

Mitral valve prolapse: associations with symptoms and anxiety.

Mitral valve prolapse has been studied extensively in the adult population, but less is known about it in children. Therefore, 813 children between 9 and 14 years of age were examined by a team of cardiologists and technicians. The children also responded to a questionnaire concerning the presence of symptoms and the What I Think and Feel anxiety instrument. The prevalence of mitral valve prolapse using auscultatory criteria was 4.2% (6.2% for girls, 2.3% for boys). Of those with mitral valve prolapse, 85% had a solitary click, 9% had a click and systolic murmur, and 6% had multiple clicks. Children with auscultatory mitral valve prolapse were less likely to have symptoms than those free of cardiac abnormalities. No difference in average anxiety scores was detected between the two groups. It is concluded that auscultatory mitral valve prolapse is common in children and not accompanied by an increased likelihood of symptoms or anxiety.

Adolescent↗
PubMed1988

Temporal pattern of alcohol consumption in the United States.

Alcohol is a major risk factor for many causes of injuries. A preliminary assessment of alcohol's involvement in specific causes of injuries must take into account when people are drinking. This study quantified the weekly and diurnal rhythm of alcohol consumption for the general U.S. population using data collected in a national survey. The data showed a strong temporal pattern consisting of more drinking on weekends with daily peaks in the early evening and troughs in the early morning. The national temporal drinking pattern was positively correlated (0.22 to 0.56) with national temporal patterns of motor vehicle accidents, a cause of injury commonly associated with drinking.

Accidents, Traffic↗
PubMedDate not supplied

Major decrements in glycated hemoglobin levels between 1978 and 1989 in patients with insulin-dependent diabetes mellitus.

The Diabetes Control and Complications Trial has shown that intensive treatment can deter the development and progression of diabetic complications. Integral to intensive treatment is improved glycemic control. To describe the trend in glycemic control for subjects with insulin-dependent diabetes mellitus, we examined the medical records of 662 subjects seen between 1978 and 1989 at the Model Demonstration Unit of the Diabetes Research and Training Center (Washington University School of Medicine). Mean value of glycated hemoglobin showed steady decline from a peak of 11.5% in 1979 to 9.0% in 1989. This decline was observed both in subjects evaluated only once (annual rate of decline estimated from linear regression, -0.17 +/1 0.03; p = 0.0001) and in subjects evaluated more than once (annual rate of decline estimated from growth curves, -0.18 +/- 0.06; p = 0.0001). These results suggest that substantial lowering of glycated hemoglobin has occurred during the last decade. This reduction should result in a lowered risk of diabetic complications.

Adolescent↗