The relationship between self-rated health and depressive symptoms in an epidemiological sample of community-dwelling older adults

OBJECTIVE

To confirm the association between depression and self-rated general health, independent of demographics, functional disability, physical illness burden, and health services utilization.

DESIGN

Logistic regression analyses of data obtained in a cross-sectional epidemiological survey.

SETTING

The mid-Monongahela Valley, a rural, nonfarm, low SES community.

PARTICIPANTS

Random sample of 880 subjects aged 65 and older.

MEASUREMENTS

The dependent variable was self-rated overall health, categorized as excellent, good, fair, or poor. The independent variables were demographics (age, gender, education), number of depressive symptoms, number of impaired instrumental activities of daily living (IADLs), measures of physical illness burden (individual medical conditions, number of affected organ systems or disease processes, and number of prescription medications), and measures of health services utilization (number of visits to physicians, and acute hospitalization).

RESULTS

Univariate analyses indicated that poorer self-rated health was associated with lesser education, higher numbers of depressive symptoms, impaired IADLs, prescription medications, physician visits, hospitalizations, and affected organ systems, and with the presence of several specific conditions. However, multiple logistic regression analyses revealed that only the following variables were associated independently with poorer self-rated health: age less than 75 years, education less than high school graduation, greater numbers of depressive symptoms, impaired IADLs, prescription medications, and physician visits.

CONCLUSIONS

Even when controlling for physical illness and functional disability, subjective rating of overall health remains strongly and independently associated with depressive symptoms.

Over-the-counter medication use in an older rural community: the MoVIES Project

OBJECTIVE

To examine the self-reported use of over-the-counter (OTC) medications and the factors associated with OTC use in a rural older population.

DESIGN

A cross-sectional study of an age-stratified random community sample.

SETTING

The mid-Monongahela Valley, a rural area of Southwestern Pennsylvania.

PARTICIPANTS

A total of 1059 older individuals with a mean age of 74.5 (+/- 5.5) years, 96.9% of whom were white and 57.3% of whom were women.

MEASUREMENTS

Self-reported over-the-counter drug use and demographic information, and information about prescription drug use and recent use of health services.

RESULTS

The majority (87.0%) of the sample were taking at least one OTC medication; 5.7% reported taking five or more OTCs. Women took significantly more OTCs than did men (P < .001). Individuals with more education took significantly more OTCs than those who had less (P = .018). The OTC category used most commonly was analgesics (66.3% overall), followed by vitamin and mineral supplements (38.1%), antacids (27.9%), and laxatives (9.7%). The use of analgesics decreased significantly (P = .018) with increasing age, whereas the use of laxatives increased significantly (P < .001). Women were more likely than men to be using each of these four major OTC groups. Unlike the associations with prescription drug use we reported previously in the same population, there were no significant associations for overall OTC use with age or with the use of health services. However, although vitamin use (as an example of an OTC drug taken for "preventive" purposes) was not associated with health services use, the use of laxatives (as an example of a "curative" OTC) was significantly associated (P < or = .002) with a greater number of physician visits, emergency room visits, hospitalizations during the past 6 months, home health care service utilization, and number of prescription medications.

CONCLUSIONS

A substantial proportion of our older sample reported using a variety of over-the-counter drugs. Analgesics and vitamin/mineral supplements were the most frequently used categories. Women and those with more education were taking more OTC drugs. OTC use was not related to age, but the use of analgesics decreased with age while laxative use increased with age. Unlike prescription drug use, overall OTC drug use was not associated with health services utilization.

Association between dementia and elevated TSH: a community-based study

We report on 194 individuals (96 men and 98 women), aged 65 and over, who had dementia assessments and basal TSH measurements as part of an ongoing epidemiological study of dementing disorders in a larger population. Dementia was diagnosed according to DSM-III-R and measured by the Clinical Dementia Rating scale; CDR scores of 0, 0.5, and > or = 1, represent individuals with no dementia (n = 122), possible dementia (n = 29), and definite dementia (n = 43), respectively. The odds ratio for the association of elevated TSH with definite dementia (CDR > or = 1) was 3.8 (95% confidence interval = 1.6, 9.1) and with possible and/or definite dementia (CDR > or = 0.5) was 3.8 (95% confidence interval = 1.6, 9.2), after adjusting for the effects of age, gender, and level of education. This is the first community-based study to report an association between TSH elevation and dementia. Our findings are consistent with recent evidence that subclinical hypothyroidism is associated with cognitive impairment, and that thyroidal state may influence cerebral metabolism.

Prevalence and persistence of sleep complaints in a rural older community sample: the MoVIES project

OBJECTIVES

To determine the prevalence and 2-year persistence of subjective sleep complaints in a rural older population.

DESIGN

A prospective epidemiological study of an age-stratified random community sample.

SETTING

The mid-Monongahela Valley, a rural area of Southwestern Pennsylvania.

PARTICIPANTS

A total of 1050 individuals with a mean age of 74.4 years (range, 66-97; SD = 5.5); 57.2% were women.

MEASUREMENTS

Subjective responses to questions about sleep complaints, classified as "never" experienced versus "sometimes" or "usually"; these questions reflected difficulty falling asleep (DFA), sleep continuity disturbance (SCD), early morning awakening (EMA), and uncontrollable daytime somnolence (DaSom). Subjects were also asked about snoring. Frequencies of these complaints were used to calculate their prevalence; those who remained in the study 2 years later were asked the same questions again to determine the persistence of sleep complaints. On the first occasions, subjects were also asked for "usual" estimates of how long they took to fall asleep, how many times they wakened during the night, and how many hours of sleep they obtained per night.

RESULTS

With regard to prevalence, 385 (36.7%) subjects reported DFA, 301 (28.7%) reported SCD, 201 (19.1%) reported EMA, and 198 individuals (18.9%) reported DaSom. Of those who knew whether they snored, 334 (40.0%) reported snoring loudly during sleep. Within the age range of this group, age was not associated with complaints of insomnia or somnolence; however, older age was associated with a significantly lower prevalence of snoring (P < .001). All three insomnia complaints were significantly more common among women (P < .001). Snoring was significantly more common among men (P < .005), but there was no gender difference in DaSom. With regard to subjective estimates, of those reporting DFA, 49.2% reported that sleep latency exceeded an hour; of those reporting SCD, 26.2% reported waking three or more times per night; and of the entire sample, 11.8% reported 5 hours or less, whereas 12.7% reported 9 to 12 hours, of sleep per night. Approximately 2 years later, among those who had reported insomnia previously and participated in the follow-up wave, the persistence of DFA was 74.9%, that of SCD 68.9%, that of EMA 47.3%, and that of known snoring was 59.6%. The persistence of DaSom, however, was only 5.7%; only DaSom was significantly (P = .049) associated with mortality.

CONCLUSIONS

Sleep complaints were common among these older individuals. Because these data were collected prospectively, they also provide objective evidence that insomnia is relatively persistent or chronic among older adults. This finding has implications for the diagnosis and long-term management of sleep disorders in older people. Derivation from a random community-based sample rather than from samples of patients or volunteers makes these data more generalizable to the general older population. Finally, these data describe a rural older populations, a group which, in general, is medically underserved and understudied.

Use of prescription medications in an elderly rural population: the MoVIES Project

OBJECTIVE

To determine the pharmacoepidemiology of prescription drug use in a rural elderly community sample, specifically the numbers and categories of medications taken and the factors associated with them.

DESIGN

Cross-sectional community survey.

SETTING

The mid-Monongahela Valley of southwestern Pennsylvania.

PARTICIPANTS

An age-stratified random sample of 1360 community-dwelling individuals, aged 65 years and older.

MEASURES

Self-reported use of prescription drugs demographic characteristics, and use of health services.

RESULTS

Nine hundred sixty-seven participants (71%) reported regularly taking at least one prescription medication and 157 (10%) reported taking five or more medications (median 2.0, range 0-13). Women took significantly more medications than men (median 2.0, range 0-13 and median 1.0, range 0-9, respectively; p = 0.01). The use of a greater number of medications was independently and statistically significantly associated with older age, hospitalization within the previous 6 months, home health care in previous year, visit to a physician within the previous year, and insurance coverage for prescription medication. Individuals older than 85 years were significantly more likely to be taking cardiovascular agents, anticoagulants, vasodilating agents, diuretics, and potassium supplements. Significantly more women than men were taking nonsteroidal antiinflammatory drugs, antidepressants, potassium supplements, and thyroid replacement medications.

CONCLUSIONS

Both the number and the types of prescription medications vary with age and gender. The demographic and health service use variables associated with greater medication use in the community may help define high-risk groups for polypharmacy and adverse drug reactions. Longitudinal studies are needed.

Genetic and aging epidemiology. The merging of two disciplines

For future research in aging epidemiology to be meaningful, it will have to integrate knowledge and skills from multiple areas, including the application of genetic and molecular epidemiologic techniques to the study of the elderly. This article begins with an overview of genetic and molecular epidemiology, followed by a discussion of several unique methodologic issues that need to be considered in the interpretation of genetic and molecular findings of epidemiologic studies of the elderly.

Characteristics of rural homebound older adults: a community-based study

OBJECTIVE

To determine the frequency and characteristics of homebound older adults in a rural community.

DESIGN

An epidemiological survey of an age-stratified random community sample.

SETTING

The rural mid-Monongahela Valley in Southwestern Pennsylvania.

PARTICIPANTS

A total of 878 noninstitutionalized persons aged 68 years and older, fluent in English, and with at least grade 6 education.

MEASUREMENTS

The frequency with which subjects left their homes, the Mini-Mental State Examination (MMSE) score, and additional information on demographics, self-reported health problems, health services utilization, IADLs, depression, and social support were measured.

RESULTS

10.3% of the sample was classified as homebound. In univariate analyses, being homebound was found to be associated significantly (P < .001) with being older, female, and widowed and with MMSE and IADL impairment, with more depressive symptoms and worse social supports, fair to poor self-rated general health, weight loss, and histories of stroke, angina, arthritis of the spine, and falls. In a multiple regression model, variables associated independently with homebound status were gender (odds ratio = 9.4, 95% confidence interval = 3.6 - 24.9), weight loss (OR = 3.7, CI = 1.7 - 8.2), IADL impairment (OR = 2.6, CI = 2.1 - 3.1), and depressive symptoms (OR = 2.1, CI = 1.3 - 3.2). Being homebound was also associated with recent acute hospitalization and use of home health and social services.

CONCLUSIONS

These data provide evidence that homebound older adults have a disproportionate share of morbidity and disability and suggest a sociodemographic and clinical profile to help identify those older people at risk of being or becoming homebound. They also point to the need for home-based health services for the older adults, particularly in medically underserved communities such as rural areas.

Hypertension from carotid occlusion decreases renal papillary plasma flow, hypotension from hemorrhage increases it, an autoregulatory paradox

Renal papillary plasma flow was tested during acute increases and decreases of perfusion pressure using the 125I-labelled albumin technique. Increases of pressure were attained through ligation of carotid arteries; decreases of pressure through modest hemorrhage. In 12 control rats with blood pressure of 144 mmHg, the papillary plasma flow averaged 21.5 ml per 100 g papilla per min. In 12 rats after ligation of carotid arteries, blood pressure rose from 143 mmHg to 172, a 20% increase. The papillary plasma flow in these rats with acute hypertension averaged 17.9 ml per 100 g papilla per min, a 17% decrease (p < 0.025). In another 12 rats after bleeding 1% of body weight over a period of 10 min, blood pressure dropped from 146 mmHg to 104, a 29% decrease. The papillary plasma flow in these rats with acute hypotension averaged 26.0 ml per 100g papilla per min, a 21% increase (p < 0.025). The decrease in papillary plasma flow during acute hypertension strongly suggests an increased vascular resistance of the descending vasa recta, while the increase in papillary plasma flow during acute hypotension suggests that vasodilatation occurred in these vessels. This dilatation may be produced by the local release of prostaglandins or other vasoactive substances. Thus, the renal papilla appears to "overshoot" its autoregulation of plasma flow, with actual reduced flow during an acute blood pressure rise and increased flow during an acute blood pressure fall, an enigmatic over-compensation.

Effect of education and gender adjustment on the sensitivity and specificity of a cognitive screening battery for dementia: results from the MoVIES Project. Monongahela Valley Independent Elders Survey

The Monongahela Valley Independent Elders Survey (MoVIES) used a multiphase process to identify demented persons among 1,366 randomly selected noninstitutionalized individuals 65 years and older. Raw test scores from a cognitive screening battery were used to identify cognitively impaired individuals who were referred for a clinical evaluation. Subsequently, test scores were adjusted for education and gender within age strata. Adjusting test scores affected sensitivity for dementia only among the most educated, increasing sensitivity among younger subjects and decreasing among the older subjects. Specificity increased among the least educated and the oldest subjects. Overall, the adjusted criteria did not perform as well as the unadjusted criteria in this sample. Adjustment for education will not necessarily improve the ability of a screening battery for cognitive function to identify demented persons, particularly if unadjusted scores perform well.

Cognitive stability over 2 years in a rural elderly population: the MoVIES project

In an ongoing prospective community study, a random sample of rural elderly persons was screened with cognitive tests (including the CERAD neuropsychological battery) at study entry and an average of 2 years later. We examined 1,017 subjects, nondemented at study entry, at both waves, with the Mini-Mental State Exam, Story Recall, Word List Recall and Recognition, Boston Naming Test, Verbal Fluency, Praxis, Clock Drawing, and Trailmaking. Overall, the cognitive performance was stable, with either no mean change or a small mean decline over 2 years; however, standard deviations were relatively large, implying individual variation of questionable clinical significance. These data provide a set of population-based longitudinal cognitive norms and have implications for dementia screening.

Cognitive test performance in a community-based nondemented elderly sample in rural India: the Indo-U.S. Cross-National Dementia Epidemiology Study

Interpretation of cognitive test performance among individuals from a given population requires an understanding of cognitive norms in that population. Little is known about normative test performance among elderly illiterate non-English-speaking individuals. An age-stratified random sample of men and women, aged 55 years and older, was drawn from a community-based population in the rural area of Ballabgarh in northern India. These Hindi-speaking individuals had little or no education and were largely illiterate. A battery of neuropsychological tests, specially adapted from the CERAD neuropsychological battery, which was administered to this sample, is described. Subjects also underwent a protocol diagnostic examination for dementia. Norms for test performance of 374 nondemented subjects on these tests are reported across the sample and also by age, gender, and literacy.

Dementia among elderly apolipoprotein E type 4/4 homozygotes: a prospective study

The E*4 allele of the apolipoprotein E (APOE) gene on chromosome 19 has been shown to be an age- and dose-related risk factor for Alzheimer's disease. Of 870 elderly women participating in an osteoporosis study, 13 were previously found to be homozygous for the APOE*4 allele; 1 was deceased and the rest were assessed for dementia in a "piggyback" study of dementia. One had moderate [clinical dementia rating (CDR = 2], 2 had mild dementia (CDR = 1), and 2 had possible dementia (CDR = 0.5). All 3 women over 80 years were definitely demented (CDR > or = 1). Typically, genetic studies of Alzheimer's and other dementias require the identification and diagnosis of large numbers of demented subjects, at considerable expense, followed by genotyping or phenotyping with a relatively low yield of individuals with rare alleles. We demonstrate a more cost-effective approach in which the population is first phenotyped and then stratified by phenotype, so that diagnostic evaluation can be restricted to individuals with the phenotype of interest.

Studies of the epidemiology of dementia: comparisons between developed and developing countries

By the year 2025, 68% of the world's population aged 65 and above, nearly 277 million people, will be residing in developing countries. The less industrialized nations have been the least studied to date, and may yield significant new information about the etiology and risk factors for Alzheimer's disease (AD) and other dementias. Although it is readily apparent that cross-national and cross-cultural comparisons are desirable, these can be meaningful only if based on comparable methodology. In this work we will discuss some general conceptual and methodological issues regarding epidemiological studies of dementia in developing countries. The topics discussed include community-based screening for dementia, screening instruments and their application in cross-cultural studies, steps in standardization of new or modified neuropsychological tests, and some special considerations in studying uneducated/illiterate populations.

Cognitive impairment and the use of health services in an elderly rural population: the MoVIES project. Monongahela Valley Independent Elders Survey

OBJECTIVE

To describe the patterns of use of health and human services by elderly rural individuals and to determine whether cognitively impaired persons had a distinctive pattern of service utilization.

DESIGN

An epidemiological survey and cognitive screening of an age-stratified random community sample.

SETTING

The mid-Monongahela Valley, a rural community in Southwestern Pennsylvania.

PARTICIPANTS

1366 non-institutionalized persons aged 65 years and older, fluent in English, and with at least a sixth grade education.

MEASUREMENTS

We administered a battery of cognitive screening tests (the Mini-Mental State Examination; Immediate and Delayed Recall of a Story; Immediate and Delayed Recall of a Word List; CERAD modification of the Boston Naming Test; Verbal Fluency for initial letters P and S and for names of Fruits and Animals; Temporal Orientation; Praxis; Clock Drawing; and Trailmaking Tests A and B.) We also obtained basic demographic information and inquired about the use of health and human services in the previous year.

RESULTS

Approximately 10% of the sample was classified (by operational criteria) as cognitively impaired. In univariate analyses, cognitive impairment was found to be significantly associated with the use of certain health services: hospitalization in the previous 6 months (odds ratio, OR = 2.1; 95% CI = 1.3, 3.3), previous nursing home use (OR = 9.3; 95% CI = 3.8, 22.9), home health care (OR = 4.6; 95% CI = 2.7, 8.0), social services (OR = 6.5; 95% CI = 3.4, 12.4), mental health services (OR = 2.8; 95% CI = 1.2, 6.2), and the regular use of prescription medications (OR = 2.0; 95% CI = 1.3, 3.2). Visits to physicians were not significantly different between the impaired and unimpaired groups. In a multiple regression model, which included age and educational level, the use of home health care (OR = 3.4; 95% CI = 1.8, 6.4) and social services (OR = 2.3; 95% CI = 1.1, 4.9) remained significantly associated with cognitive impairment.

CONCLUSIONS

The association of cognitive impairment with the use of these health and human services underscores the general frailty of the impaired group. These findings also point to potential target groups in the community for further evaluation and services for dementia. The findings support the need for education regarding cognitive impairment and dementia to be made available to providers of these services, particularly informal social services such as those provided by church groups.

Sensitivity and specificity for dementia of population-based criteria for cognitive impairment: the MoVIES project

BACKGROUND

Few norms exist for the elderly on the cognitive tests commonly used to screen for dementia; conventional cutpoints used in clinical settings may be of limited value in population screening. A particular problem is posed by elderly populations with low educational levels, as performance on most cognitive tests is affected by education. Thus, a healthy but poorly educated population may obtain test scores in the range considered impaired in the clinical setting.

METHODS

A random sample of 1,367 subjects aged 65+ years was screened for dementia in a rural community in Southwestern Pennsylvania. Two sets of cognitive measures were used: a global cognitive scale (the MMSE) and a brief battery of tests tapping a variety of cognitive domains. Rather than using a priori cutoff scores, we examined the specificity and sensitivity for dementia of two operationally defined levels of cognitive impairment, at the 5th and 10th percentiles of the study sample on each set of measures.

RESULTS

Results suggest that the screening of multiple cognitive domains at the 10th percentile had significantly greater sensitivity but not lower specificity for definite dementia than did the use of the single global scale.

CONCLUSION

Our data support the use of population-based cutpoints over standard cutoff scores, in that the global scale at the conventional cutoff was less sensitive than the battery at the same percentile, and because adequate norms do not exist for tests such as those in the battery.

Possible human health hazards from outbreak of epizootic ulcerative syndrome (EUS) in fish in the Asia-Pacific region

Acid fast rods, constituting chemoautotrophic nocardioform bacteria, could be repeatedly cultivated and isolated and propagated indefinitely in vitro from fish actinomycotic macrophage granuloma from the massive epizootics of ulcerative disease syndrome of fish in eastern India during 1988-90. The possible human hazards of zoonotic actinomycotic infections as a result of handling and consumption of such fish are assessed.

Effects of age, gender, and education on cognitive tests in a rural elderly community sample: norms from the Monongahela Valley Independent Elders Survey

A random sample of 1,350 persons aged 65 years and older in a rural community underwent cognitive screening as part of a survey to establish a population-based registry of dementing disorders. The screening battery included the neuropsychological tests of the assessment protocol used in the National Institute on Aging multicenter Consortium to Establish a Registry for Alzheimer's Disease (CERAD). This paper reports a large body of normative neuropsychological data from this sample with members of relatively low socioeconomic status. Age, sex, and educational level were found to have statistically significant effects on test scores. The implications of these findings for the establishment of screening cutoff scores are discussed.

In SHR rats, dietary potassium determines NaCl sensitivity in NaCl-induced rises of blood pressure

The current study tested whether the spontaneously hypertensive rats (SHR) from Charles River Laboratories are resistant or not to NaCl-induced rises of blood pressure and deaths. These rats are fairly NaCl-resistant on a 2.1% high K diet, whereas they are quite susceptible to NaCl-induced hypertension and deaths on a 0.5% normal K diet. Thus, a high K diet strongly protects against a NaCl-induced rise of blood pressure as well as deaths in these SHR rats. Hence the level of dietary K determines the degree of NaCl sensitivity in these SHR rats.

Deleterious effects of high magnesium diets and beneficial effects of high potassium diets in hypertensive stroke-prone rats

The effect of varying amounts of dietary magnesium (Mg) in conjunction with potassium (K) on hypertension and stroke mortality in hypertensive stroke-prone (SHRsp) rats was studied. These results show that high K (2.1%) diets strongly protect against stroke mortality and rises of blood pressure, while high Mg (0.26%) diets appeared to increase stroke mortality and accelerate the rise of blood pressure in SHRsp rats. Similarly, medium high (1.3%) levels of K in the diet significantly reduced blood pressure and stroke mortality but not nearly as much as the 2.1% K in the high K diet.

Serial sevens versus world backwards: a comparison of the two measures of attention from the MMSE

This paper reports on a comparison of the two alternative tests of attention in the Mini-Mental State Examination (MMSE), a well-known cognitive screening tool. The two tests, serial subtraction by seven and backwards spelling of the word world, are often used interchangeably. In a large population-based sample, the two tests were found to be weakly associated with each other, with the former test appearing more difficult, although both were strongly associated with educational level. The authors discuss the implications of this finding in clinical and research settings, and make recommendations for more consistent use of the instrument.

Dietary K determines NaCl sensitivity in NaCl-induced rises of blood pressure in spontaneously hypertensive rats

The current study tested whether the spontaneously hypertensive rats (SHR) from Charles River Laboratories are resistant or not to NaCl-induced rises of blood pressure and stroke deaths. These rats are fairly NaCl-resistant on a 2.1% high K diet, whereas they are quite susceptible to NaCl-induced hypertension and stroke deaths on a 0.5% normal K diet. Thus, a high K diet strongly protects against an NaCl-induced rise of blood pressure as well as stroke deaths in these SHR rats. Hence the level of dietary K determines the degree of NaCl sensitivity in these SHR rats.

Starting fights: the debate as teaching tool

During a one-year experiment in postgraduate psychiatric education, residents participated in live debates instead of attending traditional lectures and seminars. A variety of controversial topics in psychiatry were covered. Both residents and faculty rated the debate as a thought-provoking and highly effective teaching tool, and a fun one, to boot.

Physical demonstration of a high molecular weight bacteriocin plasmid in Vibrio cholerae by genetic transformation process

Bacteriocinogeny was transferred at high frequencies from bacteriocinogenic (Bac+) V. cholerae strains to non-bacteriocinogenic (Bac-) recipients in the in situ genetic transformation system on agar surface. DNA extracted from samples of growth of bacteria transformed to Bac+ were obtained at 2 h intervals following contact with the sterile agar surface where the donor had grown previously. This showed acquisition of a high molecular weight plasmid which could be physically demonstrated best in the 6 h sample of the Bac+ transformants; their 4 h samples failed to show this specific plasmid, while it was demonstrable only as a faint band in the 8 h samples.

'DNA' as contaminants in antibiotics and its capacity to transform bacteria to drug resistance

DNA/and deoxyribose sugars were detected in streptomycin (Sm), kanamycin, polymyxin, penicillin G, ampicillin, methicillin, cloxacillin and mitomycin C in small amounts/traces. Stained DNA could be feebly visualized directly in Sm run in agarose gel, which improved after its separation and concentration. These DNA materials were DNase sensitive, RNase and pronase resistant, and appeared to consist of fragments, c. less than or equal to 6 Mdal; this could repeatedly transform to SmR several recipient enterobacteria and vibrios; E. coli C600 and S. typhi 57, after such transformation revealed similar plasmid DNA bands that were absent in their wild-types. G + C mole% of plasmid and chromosomal DNA of recipient (57) along with that of Streptomyces griseus reference strain, suggested an extraneous origin for the plasmid DNA.

High magnesium diets increase blood pressure and enhance stroke mortality in hypertensive SHRsp rats

The effect of varying amounts of dietary magnesium in conjunction with potassium (K) on hypertension and stroke mortality in hypertensive stroke prone (SHRsp) rats was studied. These results show that high K (2.1%) diets strongly protect against stroke mortality and rises of blood pressure, while high magnesium (Mg) (0.26%) diets appeared to increase stroke mortality and accelerate the rise of blood pressure in SHRsp rats. Similarly, medium-high (1.3%) levels of K in the diet significantly reduced blood pressure and stroke mortality but not nearly as much as the 2.1% K in the high K diet.

Acute prostaglandin reduction with indomethacin and chronic prostaglandin reduction with an essential fatty acid deficient diet both decrease plasma flow to the renal papilla in the rat

Renal distribution of prostaglandin synthetase is mainly medullary, whereas the major degrading enzyme, prostaglandin dehydrogenase is primarily cortical. This suggests that prostaglandins (PG) released from the renal medulla could affect the medullary blood vessels. In two different experiments we studied the role of PG in the regulation of renal papillary plasma flow in the rat. First study: PG synthesis were stimulated in 34 adult Sprague-Dawley rats by bleeding from the femoral artery 1% of the body weight over a period of 10 minutes. Following this, indomethacin (a PG inhibitor, 10 mg/kg i.v.) was given slowly and then renal papillary plasma flow was measured 25 minutes after the end of infusion. In 17 indomethacin rats the renal papillary plasma flow averaged 18.8 ml/100 g/minute, whereas it averaged 23.0 in 17 non-indomethacin rats given diluent, an 18% reduction (p less than .025). Second study: Male Sprague-Dawley rats were made prostaglandin deficient by fasting rats for one week, followed by 10% dextrose fluid for one week and subsequent institution of an essential fatty acid (EFA) deficient diet for two weeks. With urinary PG excretion in prostaglandin deficient rats 28 ng/24 hours compared to 149 ng in control rats, they could be considered as prostaglandin deficient. When renal papillary plasma flow was measured, the 16 prostaglandin deficient rats had a 16% lower papillary plasma flow than 16 control rats, 21.6 vs 25.6 (p less than .005). These results clearly demonstrate that PG inhibition in rats decreases plasma flow to the papilla, strongly suggesting that PG are vasodilators for the vessels supplying the renal papilla.

Assessing depression in primary medical and psychiatric practices

A two-stage assessment of newly admitted outpatients at community mental health centers and primary medical care centers found the Center for Epidemiological Studies Depression Scale to be highly sensitive but relatively nonspecific when compared with assessments of depression by the Diagnostic Interview Schedule. Considerably higher than usual screening scores are recommended with both patient populations to improve the efficiency of the Center for Epidemiological Studies Depression Scale. The reasons for our finding that primary care clinicians underdiagnose depressive disorder while psychiatric clinicians overdiagnose it relative to the Diagnostic Interview Schedule include varied presentations by each sector's patients, differing clinical acumen, and factors affecting third-party reimbursement.

Dahl S rats have increased natriuretic factor in atria but are markedly hyporesponsive to it

Three experiments were carried out to determine whether atrial natriuretic factor (ANF) plays a part in Dahl hypertension. Results showed that ANF from both atria from 13 Dahl salt-sensitive (S) rats that had been fed a 4% NaCl diet for 12 weeks induced an average peak Na excretion of 23.0 muEq/min/g kidney in 13 Sprague-Dawley (SD) recipients vs 12.6 from atria from 13 salt-resistant (R) rats fed 4% NaCl (-45%, p less than 0.01), possibly indicating greater ANF secretion in S rats in order to enhance a reduced Na excretion. In 13 R rats, the ANF content in both atria increased from 14.0 after a 0.11% NaCl diet to 23.7 after 5 days of 4% NaCl diet (p less than 0.001) and then back to 12.6 after 12 weeks of 4% NaCl (p less than 0.001). Thus, ANF almost doubled after brief Na loading but returned to normal during continued Na loading. In S rats with a tendency to Na retention, ANF was elevated to about 23 in all three periods. ANF produced a 130-fold increase in natriuresis and a renal papillary plasma flow ( RPPF ) of 30.8 ml/min/100 g, 41% above the control level of 21.7, p less than 0.001. The marked increase in RPPF is very likely a partial cause of the natriuresis. A constant amount of ANF was continuously infused intravenously into 10 S rats and nine R rats all on 0.11% NaCl diets. Mean Na excretions in R and S were 5.3 and 4.6 muEq/min/100 g kidney before ANF.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of an anteroventral third ventricle lesion on NaCl hypertension in Dahl salt-sensitive rats

An anteroventral third ventricle (AV3V) lesion in the brain prevents several forms of experimental hypertension. The present experiment was designed to determine whether the AV3V lesion prevents NaCl-induced hypertension in Dahl salt-sensitive (S) rats and whether attenuation of vasopressin release reported in lesioned rats contributes to the protective effect of the AV3V lesion against hypertension. After the AV3V lesion Dahl S rats received daily injections of either vasopressin (pitressin tannate, 500 mU/kg) or vehicle during 10 wk of 8% high-NaCl diet. Sham-lesioned rats served as controls. The blood pressure in sham-lesioned rats receiving vehicle was 189 mmHg after 10 wk of high-NaCl diet. Lesioned rats given vehicle showed a significantly smaller increase in blood pressure than sham-lesioned rats (P less than 0.001), the blood pressure averaging 161 mmHg at 10 wk. Lesioned rats given vasopressin also showed a smaller increase in blood pressure than sham-lesioned rats (P less than 0.05), but the final blood pressure averaged 176 mmHg and was significantly higher than that of lesioned rats given vehicle (P less than 0.025). Vasopressin injections corrected the hypernatremia in lesioned rats. In another experiment the effect of the AV3V lesion on the renal papillary plasma flow (RPPF) in Dahl S rats was studied. Dahl S rats have a lower RPPF than Dahl salt-resistant (R) rats even on a low-NaCl intake. The AV3V lesion increased the RPPF by 14% in S rats (P less than 0.025). These findings suggest that NaCl-induced hypertension in Dahl S rats requires the integrity of the AV3V region for its full expression, and the ability of the AV3V lesion to attenuate the NaCl-induced hypertension in Dahl S rats is partly related to the attenuation of vasopressin release. Moreover, the AV3V lesion partly corrected one of the characteristic features of Dahl S rats, the reduction in RPPF, when compared with Dahl R rats, with both strains on a low-NaCl intake.

Potassium citrate feeding protects against nephron loss in severe sodium chloride hypertension in rats

1. Potassium citrate did not significantly increase plasma flow to the renal papilla in normotensive Dahl R rats on either low or high NaCl diets. Similarly, potassium citrate did not significantly increase papillary plasma flow in mildly hypertensive Dahl S rats on low NaCl diets. Thus potassium citrate feeding did not ordinarily alter papillary plasma flow.

2. When S rats were fed on a high (4%) NaCl diet for 24 weeks, they became severely hypertensive and developed nephrosclerosis with nephron loss. This accounted for the significant reduction in papillary plasma flow in S rats on 4% high NaCl diet with no potassium supplementation.

3. When S rats on high NaCl diet were given a supplement of KCl, they still developed severe hypertension and almost the same fall in papillary plasma flow, suggesting a similar degree of nephron loss from nephrosclerosis.

4. However, when S rats on high NaCl diet were given a supplement of potassium citrate, they still developed the same severe hypertension but, in contrast, they did not have a decrease in papillary plasma flow. This actually increased to 7% higher than in comparable S rats eating the low NaCl diet. Moreover, S rats receiving potassium citrate supplements in their high NaCl diet had a papillary plasma flow which was 34% higher than that of S rats receiving no potassium supplement in the high NaCl diet (P &lt; 0.005) and was 19% higher than that of S rats receiving KCl supplements in the high NaCl diet (P &lt; 0.04). This occurred even though the rats receiving potassium citrate were severely hypertensive.

5. Thus potassium citrate feeding protected against nephron loss from nephrosclerosis during severe NaCl-induced hypertension, whereas KCl feeding did not provide such protection.

Cardiac output and peripheral resistance in strains of rats sensitive and resistant to NaCl hypertension

The interrelationship of blood pressure, cardiac output, and peripheral resistance was studied in Dahl "S" and "R" rats after 3 days on a high (8%) NaCl diet. Both "S" and "R" rats were normotensive when fed a normal (0.3%) NaCl diet. After 3 days of the high NaCl diet, the "R" rats remained normotensive (BP 112 mm Hg), while the "S" rats had an elevation of arterial pressure (BP 133 mm Hg) (p less than 0.001). The cardiac outputs of both "S" and "R" rats were similar on the low NaCl diet. After 3 days of high NaCl feeding, the cardiac output of the "R" rats rose 18% above the "R" control level (p less than 0.0001), while the peripheral resistance declined 14% below the "R" control level (p less than 0.005), and the blood pressure (BP) did not change, a pattern quite contrary to the concept of "whole-body" autoregulation. With a similar 3-day high NaCl feeding in "S" rats, cardiac output (p less than 0.005) and peripheral resistance (p less than 0.05) both increased 10%, while BP rose 20%. After 7 days of high NaCl feeding, the cardiac output of the "S" rats had returned to normal, while blood pressure and peripheral resistance both continued to be elevated. This pattern of response in "S" rats could be compatible with the concept of "whole-body" autoregulation. However, since both NaCl hypertension and Goldblatt hypertension can occur in settings in which "whole-body" autoregulation appears not be to causally related, one cannot be certain whether "whole-body" autoregulation is playing a causal role in the mechanism of NaCl-induced hypertension in "S" rats. It is a striking dichotomy that 3 days of high salt feeding produces vasoconstriction in "S" rats and vasodilation in "R" rats.

Evidence that prostaglandin synthesis inhibitors increase the concentration of sodium and chloride in rat renal medulla

Thirty minutes after indomethacin (10 mg/kg, iv), a prostaglandin synthesis inhibitor, had been given to 10 rats, the Na concentration in renal papilla averaged 349 mEq/kg H2O, whereas it averaged only 181 in 14 "non-indomethacin" control rats (P less than 0.0001). Papillary plasma flow was closely similar in both groups. In a subsequent study, eight "indomethacin" rats had the same papillary flow as seven non-indomethacin rats but had a papillary Na concentration of 358 vs. 185 in the non-indomethacin controls (P less than 0.0001). In nine more rats, indomethacin increased Cl concentration in papillas by 66% (P less than 0.0001), while Na concentration increased 60% (P less than 0.0001). In eight other rats, micropuncture indicated that indomethacin does not greatly alter delivery of fluid out of late proximal tubule. Meclofenamate, another inhibitor, increased papillary Na just as much as indomethacin. Papillary urea is not changed with indomethacin. Thus, papillary Na concentration was almost twice as high in indomethacin rats, despite similar papillary plasma flow and late proximal flow. Apparently, inhibiting prostaglandin synthesis is associated with either a great increase in Na or Cl "pumping" or a great decrease in Na or Cl "leak" in either collecting duct or ascending limb, or in both. The collecting duct and papillary interstitial cells both synthesize prostaglandins, which seem to have a profound effect on medullary net Na transport.

Low renal papillary plasma flow in both Dahl and Kyoto rats with spontaneous hypertension

Abnormally low plasma flow to renal papilla characterizes Dahl hypertension. When eating a normal Na diet (0.3% NaCl) both hypertension-sensitive (S) rats and hypertension-resistant (R) rats, 16 weeks old, have fairly normal blood pressure (BP), averaging 144 and 129 mm Hg, respectively. However, even in this barely hypertensive state, 18 S rats had a 31% lower papillary plasma flow (Lilienfield method) than 22 R rats, 19.2 ml/100 g of papilla per min compared to 25.6 (P less than 0.001). When a high (8%) NaCl diet was fed for 7 days, R rats increased papillary plasma flow from 25.6 on 0.3% NaCl to 33.8 on 8% NaCl, a 32% rise (P less than 0.001). S rats increased papillary flow from 20.4 to 24.8, a 22% rise (P less than 0.05). When a high (8%) NaCl diet was fed for 4 weeks, R rats increased papillary plasma flow from 25.7 ml/100 g per min on 0.3% NaCl to 29.5 ml/100 g per min on 8% NaCl, a 15% rise (P less than 0.025). S rats increased papillary flow from 17.7 to 20.0 ml/100 g per min (not significant). S rats on 8% NaCl had a papillary flow 32% lower than R rats on 8% NaCl (P less than 0.001). BP of S rats rose to 162 mm Hg after 4 weeks on 8% NaCl; in R rats, BP did not rise at all. S rats on 0.3% NaCl have a low papillary flow even in a borderline hypertensive state. When challenged with 8% NaCl, R rats increased papillary flow, an adaptation possibly important for the natriuresis. S rats failed to achieve this same high papillary flow. Lacking this adaptation, hypertension may then conceivably occur in S rats to accomplish natriuresis through a "pressure natriuresis" mechanism. Papillary flow also decreased by 11% in 26 Kyoto 17-week-old spontaneously hypertensives (BP, 182 mm Hg) compared to 24 Kyoto normotensives (BP, 118 mm Hg), 29.5 vs 33.2 ml/100 g per min (P less than 0.001). Thus, low papillary flow exists in both hypertensions.