Biomedical subjects

L R White

Publications and source records attributed to L R White.

At least 91 records · Page 5Linked to original sources

PubMed1993

Untreated blood pressure level is inversely related to cognitive functioning: the Framingham Study.

It was hypothesized that blood pressure would be inversely related to cognitive functioning, if unconfounded with antihypertensive medication and measured over many occasions prior to neuropsychological testing. For stroke-free Framingham Study participants aged 55-88 years (n = 1,702), blood pressure levels were averaged over five biennial examinations (1956-1964) when few hypertensives were being treated, and examined in relation to neuropsychological tests administered between 1976 and 1978. With age, education, occupation, cigarette smoking, alcohol consumption, and gender controlled, blood pressure levels and chronicity of hypertension were inversely related to the composite score and measures of attention and memory. This was true for the full sample, for a subsample untreated during blood pressure measurement (n = 1,485), and for a subsample untreated throughout the entire study period (n = 1,038). For example, decline per 10 mmHg increment in blood pressure ranged from -0.04 to -0.07 standard score units (z) for the composite score. A negative finding previously was most likely due to blood pressure measurement concurrently with neuropsychological testing, or too few measurements. Hypertension-associated pathogenic processes may cause mild cognitive impairment, but other mechanisms need to be considered.

Aged↗

PubMed1993

Sumatriptan relaxes isolated porcine ophthalmic artery, but inhibits VIP-induced relaxation.

Sumatriptan, a 5-hydroxytryptamine (5HT)1-like receptor agonist, is a new antimigraine drug which is also effective in cluster headache (CH), a disorder with marked ocular circulatory abnormalities. Sumatriptan could putatively exert a therapeutic effect in this vascular bed. The present study is an attempt to assess sumatriptan's vasoactivity in isolated porcine ophthalmic artery (POA) and to verify whether it has similar activity to 5HT, and whether it interferes with the vasodilation induced by calcitonin gene-related peptide (CGRP) and vasoactive intestinal peptide (VIP). In contrast to 5HT, sumatriptan induced only slight contraction in POA at high concentrations. However, in some artery segments pre-contracted with PGF2 alpha, sumatriptan induced a slight and short-lasting but marked relaxation. In addition, relaxations induced by VIP were inhibited significantly by sumatriptan, whereas CGRP effects were not influenced by the drug. Such reactions suggest that sumatriptan's effect in CH is probably unrelated to direct ocular arterial vasoconstriction.

Animals↗

PubMed1993

Incidence of dementia and probable Alzheimer's disease in a general population: the Framingham Study.

OBJECTIVE: To determine the incidence of dementia and Alzheimer's disease (AD) in a general population sample. BACKGROUND: Utilizing subjects in the Framingham Study cohort determined to be free of dementia in 1976 to 1978, or on biennial examination 17 in 1982, all new cases of dementia arising in this cohort over a maximum of 10 years of follow-up were ascertained. METHODS: On biennial examination 14/15, a screening neuropsychologic examination was administered to 2,117 subjects, and cases of probable prevalent dementia were identified. Beginning on examination 17 and on all successive biennial examinations, a Mini-Mental State Examination was administered. Subjects previously free of dementia and falling below age-education levels were evaluated by a neurologist and neuropsychologist to determine if dementia was present and to ascertain the dementia type using standard criteria. RESULTS: Five-year incidence of dementia increased with age, doubling in successive 5-year age groups. Dementia incidence rose from 7.0 per 1,000 at ages 65 to 69 to 118.0 per 1,000 at ages 85 to 89 for men and women combined. Incidence of probable AD also doubled with successive quinquennia from 3.5 at ages 65 to 69 to 72.8 per 1,000 at ages 85 to 89 years. Incidence of dementia and of probable AD did not level off with age and was not different in men and women. CONCLUSIONS: In a general population sample, we determined incidence of dementia and of probable AD and will use these incident cases for study of precursors and natural history in this elderly cohort, which has been under close surveillance for over 40 years.

Adult↗

PubMed1992

Mutual modification of vasoactivity by calcitonin gene-related peptide and endothelin-1 in isolated porcine ophthalmic artery.

Vasodilation has been implicated in the pathophysiology of some headaches, but the mechanisms behind such abnormalities remain unknown. Calcitonin gene related peptide (CGRP), a peptide present in sensory trigeminal fibres, induces strong and long lasting vasodilation in cranial vessels, and has been found to be increased in jugular blood during migraine attacks. Endothelin (ET) is a recently identified potent vasoconstrictor peptide, which also induces long-lasting responses. ET-CGRP interactions may be of importance in vascular beds putatively involved in pain development in the head, and were therefore studied in isolated porcine ophthalmic arteries. Both peptides were found to induce strong and long-lasting reactions in this artery. CGRP decreased ET-induced contractions and ET decreased CGRP-induced relaxations. These effects were additive rather than synergistic.

Animals↗

PubMed1992

Substance P augments the rate of vasodilation induced by calcitonin gene-related peptide in porcine ophthalmic artery in vitro.

Peptides may function as neurotransmitters liberated antidromically by sensory nerve fibres, provoking vascular responses having potential importance in some neurological disorders. Dose-response relaxation curves induced by substance P (SP) and calcitonin gene related peptide (CGRP) have been studied in porcine ophthalmic arteries in vitro. Both peptides induced vasodilation when tested separately (CGRP much greater than SP). Because of the putative interactions between such peptides in this vascular territory, a computerised system was also used for analysing over time the response to a single addition of either 10(-8) M CGRP, 10(-8) M SP or a combination of 10(-8) M SP + 10(-8) M CGRP. SP did not augment the maximum relaxation induced by CGRP alone, but increased significantly the rate of relaxation during the initial phase of the response. The effect induced by the SP+CGRP combination was stronger than the sum of the individual SP and CGRP-induced relaxations during the first 4 min of the response, which suggests a SP-CGRP synergism in this artery.

Animals↗

PubMed1992

Cluster headache: phospholipid metabolism in polymorphonuclear cells.

Our group has previously reported significant changes in the incorporation of precursors into glycerophospholipids, particularly phosphatidylserine, in polymorphonuclear cells obtained from the peripheral blood of cluster headache patients, when compared with controls. The potential of these results led to further work using both the previous methodology and a modified isolation technique to obtain polymorphonuclear cells in as pure a state as possible. Neither the new results obtained using the original technique, nor the results with high purity polymorphonuclear cells from controls and cluster headache patients, confirm the marked changes in precursor uptake into glycerophospholipids originally reported.

Adult↗

PubMed1992

Low concentrations of lithium and cyclooxygenase inhibitors enhance endothelin-1 (ET-1)-induced contractions in human temporal artery, but not in porcine ophthalmic artery.

Endothelins are a recently discovered group of potent vasoconstrictor peptides synthesized by endothelial cells and other tissues in various species, which seem to participate in the regulation of vascular tonus. Abnormalities in vasoactivity in the head may be an important event in headache pathophysiology, although the mechanisms responsible for such constrictions and/or dilations are not known. The endothelium and its constrictor peptide, endothelin, may play a key role in such mechanisms. Of the various drugs used in the treatment of headache, lithium is an accepted treatment for cluster headache, and indomethacin is the drug of choice for the associated condition chronic paroxysmal hemicrania. The mechanism of action of these drugs in these headaches is not known. Due to the possible involvement of endothelin in headache disorders, the objective of this study was to verify the effects of lithium and cyclooxygenase inhibitors (indomethacin, acetylsalicylic acid and naproxen) on endothelin-1 (ET-1)-induced contractions in isolated human temporal arteries and porcine ophthalmic arteries. It was found that all drugs increased the (ET-1)-induced contractions in human temporal arteries. Conversely, there were no significant changes induced by the drugs in porcine ophthalmic arteries. These results are consistent with the variation of activity often seen in different vascular beds and between species. The potential importance of such reactions for the understanding of vascular changes putatively involved in headache development and treatment is discussed.

Animals↗

PubMed1992

Prevalence of dementia and probable senile dementia of the Alzheimer type in the Framingham Study.

We determined the prevalence of dementia and probable senile dementia of the Alzheimer type (SDAT) for biennial Exam 17 of the Framingham cohort (1982/1983). The prevalence of dementia was 30.5/1,000 for men and 48.2/1,000 for women and increased with advancing age. Cases of probable SDAT constituted 55.6% of all dementia cases. THe prevalence of SDAT was 11.7/1,000 for men and 30.1/1,000 for women and also increased with advancing age. Prevalence of dementia and probable SDAT were greater for women than men. The female:male ratio of prevalence for cohort members 75 years of age and older was 1.8 for all cases of dementia and 2.8 for cases of probable SDAT.

Adult↗

PubMed1991

Sleep patterns in rural elders: demographic, health, and psychobehavioral correlates.

Altered sleep patterns, including changes in bedtime, sleep latency, total sleep time, and arising time, have been reported to occur with increasing age. We examine self-reported sleep patterns in a geographically-defined population (n = 3097) of persons aged 65 years and older. Sleep patterns were characterized according to demographic variables, clinical conditions, and physical, psychological, and social functioning. Sleep latency and total hours of sleep increased with age, and older respondents went to bed earlier. The percentage of respondents who reported feeling rested in the morning decreased with age. Women went to bed later, had longer sleep latency, and fewer hours of sleep than men, and were less likely to report feeling rested than men. Sleep patterns were also related to educational attainment, self-perceived health status, physical functional status, psychotropic drug use, alcohol use, depressive symptoms, life satisfaction, and social and recreational activity level. This population study suggests that sleep problems among the elderly are sometimes associated with treatable health conditions and modifiable behavioral and environmental characteristics.

Age Factors↗

PubMed1990

Black-white differences in stroke incidence in a national sample. The contribution of hypertension and diabetes mellitus.

Although national data have consistently shown an increased risk of death from stroke among blacks, few studies have addressed the reasons for this excess mortality. We compared the incidence of stroke among 1298 blacks and 7814 whites, aged 35 to 74 years, in the 10-year follow-up of the respondents from the First National Health and Nutrition Survey. Blacks had a higher estimated incidence of stroke than whites even after adjustment for age, hypertension, and diabetes mellitus; the relative risk was 1.4 (95% confidence interval, 1.0 to 2.0) for black women and 1.1 (95% confidence interval, 0.8 to 1.6) for black men. The relative risks for stroke associated with hypertension and diabetes mellitus were unrelated to race. Although efforts to treat hypertension and diabetes are among the most important public health measures for reducing stroke, a more complete understanding of the determinants of stroke may be required to account for the excess stroke risk experienced by blacks.

Adult↗

PubMed1990

Thiazide diuretic agents and the incidence of hip fracture.

Thiazide diuretic agents lower the urinary excretion of calcium. Their use has been associated with increased bone density, but their role in preventing hip fracture has not been established. We prospectively studied the effect of thiazide diuretic agents on the incidence of hip fracture among 9518 men and women 65 years of age or older residing in three communities. At base line, 24 to 30 percent of the subjects were thiazide users. In the subsequent four years, 242 subjects had hip fractures. The incidence rates of hip fracture were lower among thiazide users than nonusers in each community; the Mantel-Haenszel relative risk of hip fracture, adjusted for community and age, was 0.63 (95 percent confidence interval, 0.46 to 0.86). The protective effect of the use of thiazides was independent of sex, age, impaired mobility, body-mass index, and current and former smoking status; the multivariate adjusted relative risk of hip fracture was 0.68 (95 percent confidence interval, 0.49 to 0.94). Furthermore, the protective effect was specific to thiazide diuretic agents, since there was no association between the use of antihypertensive medications other than thiazides and the risk of hip fracture. These prospective data suggest that in older men and women the use of thiazide diuretic agents is associated with a reduction of approximately one third in the risk of hip fracture.

Age Factors↗

PubMed1990

Longitudinally measured blood pressure, antihypertensive medication use, and cognitive performance: the Framingham Study.

The relation of longitudinally measured blood pressure to cognitive performance in the absence of clinically diagnosed cerebrovascular disease was investigated in the Framingham Study. In 1976-1978, neuropsychologic testing was administered to 1993 participants aged 55-89 years. Performance on an education-adjusted composite of these tests was examined in relation to measures of chronicity of hypertension as well as the average systolic and average diastolic blood pressure. All analyses were stratified by antihypertensive medication use during the 2 years prior to cognitive testing and adjusted for age, sex, occupation, alcohol consumption, and participation rate in prior examination cycles. Among subjects on drug therapy for hypertension, there was no association between cognitive performance and longitudinally measured blood pressure. The proportion of cycles in which hypertension was present and average systolic and diastolic blood pressure had a significant inverse relation with cognitive performance only in the group not on antihypertensive drug therapy. However, among subjects on antihypertensive medication at earlier cycles, there was a highly significant graded relation between cognitive impairment and the probability of being off medication at the time of testing. These results suggest that hypertension-related subclinical vascular disease is not an important cause of cognitive impairment in the elderly. Cognitive impairment may, however, be associated with a reduced adherence to drug treatment regimens.

Aged↗

PubMed1990

Cognitive impairment and mortality: a study of possible confounders.

Baseline neuropsychological function was assessed in 2,123 Framingham Heart Study participants and was related to mortality over an 8- to 10-year follow-up period. During that time, 573 persons died. Using Cox proportional hazards models, the authors showed poor cognitive function to be consistently associated with an increased risk of death. This association persisted after adjustment for the confounding effects of age, education, and illness. Subjects scoring below the 26th percentile of performance were at increased risk of mortality compared with high scorers (the relative risk was 1.3 for the 11th percentile-25th percentile and 1.7 for the 1st percentile-10th percentile).

Aged↗

PubMed1990

Acute complications in patients with surgical treatment of lumbar herniated disc.

The complications of surgical treatment for lumbar disc herniation (LDH) are important to know, but hard to measure because of their low incidence and varied pattern. Using data from the National Hospital Discharge Survey, which codes discharges and procedures according to the ICD-9-CM, we assessed acute complication rates for 3,289 surgically treated LDH patients and 4,025 nonoperative LDH patients, identifying complications from codiagnoses. The complication rates were significantly correlated with the postoperative length of stay and with the risk factors of obesity, hypertension, and diabetes. We found fewer instances of thrombophlebitis (0.3/1,000) and slightly lower mortality (0.9/1,000) than previously reported. Although the frequency of the cauda equina syndrome in the literature approximates our findings of 5/1,000, our data did not allow correction for the fraction of preexistent cauda equina syndromes. Our any-complication-rate is 3.7%. Even though LDH surgery is relatively safe, its complications should not be overlooked.

Cauda Equina↗

PubMed1989

A longitudinal survey of self-reported bowel habits in the United States.

Information concerning bowel habits was gathered from a representative sample of 14,407 United States adults in the first National Health and Nutrition Examination Survey in 1971-1975 and approximately 10 years later among the same individuals. The prevalence of self-reported constipation, diarrhea, infrequent defecation (three or fewer bowel movements per week), and frequent defecation (two or more bowel movements per day) increased with aging. Women were more likely than men (P less than 0.05) to report constipation (20.8% compared to 8.0%) and infrequent defecation (9.1% compared to 3.2%). Blacks were more likely than whites to report infrequent defecation (P less than 0.05). Older respondents reporting constipation were more likely to use laxatives or stool softeners than younger respondents reporting constipation, but they were also less likely to have infrequent defecation. To evaluate factors predictive of impaired bowel function, case definitions were created using information concerning complaint of constipation, laxative use, frequency of defecation, and stool consistency. Female gender, black race, fewer years of education, low physical activity, and symptoms of depression were independent risk factors for impaired bowel function. This study provides national estimates of bowel complaints and their natural history and examines possible risk factors for constipation.

Adult↗

PubMed1989

Anthropometric indicators and hip fracture. The NHANES I epidemiologic follow-up study.

A cohort of 3,595 white women aged 40-77 years was followed for an average of 10 years during which 84 new cases of hip fracture were identified. Triceps skinfold thickness and arm muscle area measured at baseline were examined as possible risk factors for hip fracture controlling for physical activity, height, menopausal status, calcium consumption, and smoking. Of these variables only arm muscle area, triceps skinfold thickness, and activity in recreation were independent predictors of hip fracture incidence using the Cox proportional hazards model. After adjustment, the estimated relative risk of hip fracture was approximately two for an increment of each anthropometric indicator (adjusted for the other) equivalent to comparing those at the 25th percentile to those at the 75th percentile (maximum width of 95% confidence intervals, 1.2-2.9). Risk of hip fracture was approximately two-fold for persons who reported little recreational exercise compared to persons who reported much recreational exercise (95% confidence interval, 1.2-3.2). Our findings are the first evidence from a prospective study that anthropometric indicators besides body mass index may have an independent relationship to risk of hip fracture.

Adult↗

PubMed1988

Correlates of cognitive function in an elderly community population.

In 1982 and 1983, brief, structured performance tests of selected areas of cognitive function were administered to 3,682 (82.1 per cent) of the residents aged 65 years and older of the geographically defined community of East Boston, Massachusetts, a center of the Established Populations for Epidemiologic Studies of the Elderly program. There was a strong inverse relation between age and performance on all four cognitive tests in analyses adjusted for sex only as well as in those adjusted for the effects of other variables. Similarly, fewer years of formal education, increasing level of disability on the modified Katz Activities of Daily Living Scale, and less prestigious occupations, as measured by the modified Duncan Socioeconomic Index, were each independently related to lower performance on all four tests.

Activities of Daily Living↗

PubMed1988

Occurrence and predictors of pressure sores in the National Health and Nutrition Examination survey follow-up.

The occurrence of pressure sores during a follow-up period of approximately 10 years is documented for a US nationwide cohort aged 55 to 75 years at baseline. Using data from the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, those who developed pressure sores were identified through death certificates, hospital discharge summaries and self-report or proxy-report. During the follow-up period, pressure sores were identified in 113 of the 5,193 respondents (2.2%) for whom follow-up information was available. Incidence over the follow-up period was 1.7% for those aged 55 to 69 at baseline and rose to 3.3% for those 70 to 75 years old. Risk factors for pressure sore development were evaluated using data collected in NHANES I at baseline. Those with identified pressure sores were compared with the remainder of their cohort and also with a control group matched on age and length of longest hospitalization or nursing home admission. Significantly increased risk for pressure sore development was found for those who at baseline were current smokers, reported being relatively inactive, had poor self-assessed health status and who were found on physician's exam to have dry or scaling skin. Neurologic abnormality on the physician's exam and anemia at baseline were also associated with increased risk of pressure sores, although these associations were of borderline statistical significance.

Age Factors↗