Dissociation of G-protein alpha from rhabdomeric membranes decreases its interaction with rhodopsin and increases its degradation by calpain

Photoactivation of invertebrate rhodopsin activates a GTP-binding protein, Gq, which in turn activates a phospholipase C (PLC) enzyme. Gqalpha is a membrane-associated protein that is progressively released from the membrane by washing with buffers containing increasing concentrations of beta-mercaptoethanol (beta-ME). Isolated, soluble Gqalpha showed a decreased ability to be activated by rhodopsin but was more active in stimulating PLC when compared with the membrane-associated form of Gqalpha. The calcium-activated protease, calpain, selectively cleaved the soluble but not the membrane-bound form of Gqalpha. Calpain cleaved a small peptide from the amino-terminus of Gqalpha reducing the ability of the G-protein to bind GTP. The uncoupling of Gqalpha from rhodopsin and subsequent calcium-dependent proteolysis to further inactivate the G-protein may therefore be a regulatory mechanism of light adaptation in rhabdomeric photoreceptors.

Physiotherapy for anterior knee pain: a randomised controlled trial

OBJECTIVE

To determine the efficacy of the individual components of physiotherapy in subjects with anterior knee pain.

METHODS

An observer blind, prospective, factorial design randomised controlled trial. 81 young adults with anterior knee pain were randomly allocated to one of four treatment groups: (1) exercise, taping, and education; (2) exercise and education; (3) taping and education; and (4) education alone. Each group received six physiotherapist-led treatments over three months. Follow up took place at three months using the following outcome measures: patient satisfaction (discharge/refer for further treatment); a visual analogue pain score; the WOMAC lower limb function score; the Hospital Anxiety and Depression scale (HAD); and quadriceps strength. At 12 months the WOMAC and HAD were assessed by postal questionnaire.

RESULTS

All groups showed significant improvements in WOMAC, visual analogue, and HAD scores; these improvements did not vary significantly between the four groups or between exercising/non-exercising and taped/non-taped patients at three and 12 months. However, patients who exercised were significantly more likely to be discharged at three months than non-exercising patients (chi(2), p<0.001). Taping was not significantly associated with discharge. Significantly greater improvements in WOMAC, visual analogue, and the anxiety score (but not the depression score) were seen in patients who were discharged than in those who were referred.

CONCLUSIONS

The proprioceptive muscle stretching and strengthening aspects of physiotherapy have a beneficial effect at three months sufficient to permit discharge from physiotherapy. These benefits are maintained at one year. Taping does not influence the outcome.

Identification of small FRAXA premutations

BACKGROUND

Diagnosis of fragile X syndrome in mentally retarded individuals is satisfactorily achieved using a Southern blot test that detects the typical triplet repeat expansion (>200 repeats) within the FMR1 gene. All such individuals inherit the mutation from a carrier, who usually shows a lower triplet repeat number and may be asymptomatic. Having identified a fragile X proband, it is necessary to identify related carriers of this familial X-linked dominant mutation to provide family counseling and testing.

METHODS AND RESULTS

For one family in which a fragile XA repeat expansion occurs, Southern blot hybridization did not give accurate sizing data because of the very small premutation associated with the unstable allele. PCR sizing methods and linkage analysis were adapted to identify family members with the premutation.

CONCLUSION

Although most carriers can be detected using Southern blot and/or direct PCR sizing tests, very small expansions (55-70 repeats) are difficult to distinguish from larger, normal alleles. We have used linkage analysis in combination with direct allele analysis to identify carriers of very small expansions of a fragile X chromosome in a four-generation family.

Quantifying the association between habitual energy expenditure and blood pressure

BACKGROUND

Previous studies have demonstrated an association between physical inactivity and hypertension, but the methods used to assess activity have been subjective and imprecise. Recently methods have become available allowing measurement of energy expenditure in free-living populations. Our aim was to employ these methods to assess the independent association between energy expenditure, cardio-respiratory fitness and blood pressure.

METHODS

In a cross-sectional study of 775 people (45-70 years) participating in a continuing population-based cohort study, energy expenditure was assessed by 4 days of heart rate monitoring with individual calibration of the relationship between heart rate and energy expenditure, a method validated against doubly-labelled water and whole body calorimetry. Cardio-respiratory fitness was assessed in a sub-maximal test. To adjust for measurement error in the assessment of usual energy expenditure and fitness, 190 subjects repeated both tests on three further occasions at 4-monthly intervals.

RESULTS

A highly significant linear trend in blood pressure was found across quintiles of the physical activity level, the ratio of total energy expenditure to basal metabolic rate. The differences in the mean systolic/diastolic blood pressure between the top and bottom quintile was 6.3/4.4 mmHg in men and 10.7/5.9 mmHg in women. These effects were independent of obesity and cardio-respiratory fitness. Correction for measurement error suggests that the true underlying relationship between usual energy expenditure and blood pressure is stronger still.

CONCLUSIONS

These findings are compatible with a strong association between usual energy expenditure and blood pressure and support public health strategies aimed at increasing overall energy expenditure.

Identification of genetic heterogeneity in Refsum's disease

Refsum's disease (MIM 266500) is a recessive disorder characterised by defective peroxisomal alpha-oxidation of phytanic acid. A Refsum's disease gene, phytanoyl-CoA hydroxylase (PAHX), has been localised to chromosome 10p13 between the markers D10S226-D10S223. This study investigated whether all cases of Refsum's disease were linked with chromosome 10p13. Eight genetically informative families comprising 92 individuals including 17 living patients with a Refsum's disease phenotype and initial plasma phytanic acid > 200 micromol/L were recruited. Linkage to the 10pter-10p11.2 region was investigated using a panel of eight dinucleotide repeat markers. Linkage analysis of this phenotypically identical cohort suggested that Refsum's disease was genetically heterogeneous (Zmax = 5.28, alpha = 0.45). Two subgroups were identified. One group of four families with eight affected individuals had a maximum multipoint lod score for linkage of 3.89 in the region D10S547 to D10S191, whilst in another three families with nine affected individuals linkage to this region was definitely excluded. Our results show that Refsum's disease is genetically heterogeneous, with up to 55% of cases not being linked to the PAHX gene locus at D10S547 to D10S223. This suggests that Refsum's disease, in common with other peroxisomal 'diseases', may be more accurately described as a heterogeneous syndrome.

Calcium hydroxylapatite deposition disease in a Great Dane Puppy

A 10-week-old male Great Dane Puppy was presented for sudden onset tetraataxia and severe paresis of the front legs. Mineral deposits were detected radiographically, at gross postmortem examination, and light microscopically between the vertebral arches of multiple cervical and lumbar vertebrae. These deposits were associated with the interarchial ligaments (ligamentia interarcualia), along the interfaces of the synovium and articular cartilage of multiple cervical, thoracic, and lumbar facets, on the dorsal aspect of several thoracic intervertebral discs, and at the insertion of muscles at the lateral aspect of several cervical and thoracic vertebral bodies. The mineral deposits were associated with a granulomatous inflammation and synovial fibrocartilaginous metaplasia and proliferation, which was focally exuberant. X-ray diffraction analyses of the mineral deposits revealed calcium hydroxylapatite as the major component. The clinical signs in this puppy were due to focal compression of the spinal cord by marked extraarticular ligament-associated fibrocartilaginous proliferation.

Increasing the cost-effectiveness of telemedicine by embracing e-health

In 1999 a national study of telemedicine in Australia led to the promotion of the concept of 'e-health', the health sector's equivalent of 'e-commerce'. A new study explored the view that, with the convergence of technologies and the consequent increase in ability to perform multiple functions with those technologies, it is unwise to promote telemedicine in isolation from other uses of technologies in health-care. The major sources of information for the study were the presentations and discussions at five national workshops held to discuss the findings of the original report on telemedicine. Nineteen case studies were identified. The case studies showed that with the convergence of technologies telehealth is becoming part of e-health. The cost-effectiveness of both telehealth and telemedicine improves considerably when they are part of an integrated use of telecommunications and information technology in the health sector.

The cost-effectiveness of teleradiology at the Women's and Children's Hospital in Adelaide

The cost-effectiveness of teleradiology was examined in a trial conducted at the Women's and Children's Hospital (WCH) in Adelaide, from February 1998 to February 1999. The trial showed that, with the large distances between remote hospitals and metropolitan hospitals, teleradiology, relative to the transfer of remote patients, could be highly cost-effective, but that a new form of cost justification is required for teleradiology for tertiary hospitals providing second opinions in special cases. A series of compelling case studies proved the economic and social value of teleradiology at the WCH.

A randomised trial of an intervention to develop health promoting schools in Australia: the south western Sydney study

OBJECTIVE

This paper describes the evaluation of a health promoting schools intervention carried out in the south western region of Sydney, Australia. The evaluation sought to assess the project's impact on structures to support the health promoting school concept and changes in health-related policies and practices within 22 local schools.

METHODS

A randomised controlled study was employed. Intervention schools were offered seminars and training in the health promoting schools concept, encouraged to use a resource kit to help them establish their school as health promoting and invited to participate in a support network. Pre- and post measures of awareness, school structures and policies and practices to support the development of a health promoting school were taken and intervention and control schools compared.

RESULTS

There was an increased level of awareness of the health promoting school concept among intervention schools. However, there were no significant changes in health-related policies and practices at the school level, among both intervention and control schools.

CONCLUSIONS

A longer time frame and more structured support are required to influence school structures to support the development of a health promoting school.

IMPLICATIONS

To facilitate organisational change in schools, health promoting school interventions need to provide structured support for schools and recognise that change takes time. A committee to initiate action, a plan to guide work and school support are likely to facilitate the adoption of the health promoting schools approach. Further work to refine the measurement of school-based action and its outcome and the development of indicators for a health promoting school is needed.

DNA sequence elements located immediately upstream of the -10 hexamer in Escherichia coli promoters: a systematic study

We have made a systematic study of how the activity of an Escherichia coli promoter is affected by the base sequence immediately upstream of the -10 hexamer. Starting with an activator-independent promoter, with a 17 bp spacing between the -10 and -35 hexamer elements, we constructed derivatives with all possible combinations of bases at positions -15 and -14. Promoter activity is greatest when the 'non-template' strand carries T and G at positions -15 and -14, respectively. Promoter activity can be further enhanced by a second T and G at positions -17 and -16, respectively, immediately upstream of the first 'TG motif'. Our results show that the base sequence of the DNA segment upstream of the -10 hexamer can make a significant contribution to promoter strength. Using published collections of characterised E.coli promoters, we have studied the frequency of occurrence of 'TG motifs' upstream of the promoters' -10 elements. We conclude that correctly placed 'TG motifs' are found at over 20% of E.coli promoters.

Prenatal ethanol exposure reduces spinal cord motoneuron number in the fetal rat but does not affect GDNF target tissue protein

Fetal rats were exposed throughout gestation to one of three diets: an ethanol-containing liquid diet, a liquid diet with the isocaloric substitution of sucrose for ethanol or a laboratory chow control diet. At postnatal day 1 (P1), the spinal cords were taken for analyses of motoneuron number and size. These analyses revealed a significant loss of motoneurons and a reduction of motoneuron size in the ethanol-exposed animals, compared to both sucrose and chow controls. Spinal cord length and ventral horn volume were not altered as a result of ethanol treatment, so the change in motoneuron number cannot be attributed to volumetric changes. The content of the motoneuron survival factor glial cell-line-derived neurotrophic factor (GDNF) was also assessed in the P1 limb motoneuron target tissue. This analysis was undertaken because GDNF is a potent survival factor for developing motoneurons and has been shown to protect this population from ethanol neurotoxicity. Thus, its depletion could contribute to motoneuron loss. These analyses, using the ELISA assay, did not detect reductions in GDNF in the ethanol-exposed animals. Therefore, alterations in other neurotrophic factors or ethanol neurotoxicity by other means appear to be responsible for the motoneuron loss. These results are consistent with earlier studies in the chick embryo, which also found reduced motoneuron numbers as a function of developmental ethanol exposure, and point again to the general lethality of ethanol to the developing nervous system.

An integrated map of human 6q22.3-q24 including a 3-Mb high-resolution BAC/PAC contig encompassing a QTL for fetal hemoglobin

Genetic studies have previously assigned a quantitative trait locus (QTL) for hemoglobin F and F cells to a region of approximately 4 Mb between the markers D6S408 and D6S292 on chromosome 6q23. An initial yeast artificial chromosome contig of 13 clones spanning this region was generated. Further linkage analysis of an extended kindred refined the candidate interval to 1-2 cM, and key recombination events now place the QTL within a region of <800 kb. We describe a high-resolution bacterial clone contig spanning 3 Mb covering this critical region. The map consists of 223 bacterial artificial chromosome (BAC) and 100 P1 artificial chromosome (PAC) clones ordered by sequence-tagged site (STS) content and restriction fragment fingerprinting with a minimum tiling path of 22 BACs and 1 PAC. A total of 194 STSs map to this interval of 3 Mb, giving an average marker resolution of approximately one per 15 kb. About half of the markers were novel and were isolated in the present study, including three CA repeats and 13 single nucleotide polymorphisms. Altogether 24 expressed sequence tags, 6 of which are unique genes, have been mapped to the contig.

Essentials of the diagnosis of heart failure

Although heart failure is a common clinical syndrome, especially in the elderly, its diagnosis is often missed. A detailed clinical history is crucial and should address not only current signs and symptoms of heart failure but also signs and symptoms that point to a specific cause of the syndrome, such as coronary artery disease, hypertension or valvular heart disease. It is important to determine whether the patient has had a previous cardiac event, in particular a myocardial infarction. The physical examination should include Valsalva's maneuver, a test that is highly specific and sensitive for the detection of left ventricular systolic and diastolic dysfunction in patients with heart failure. An electrocardiograph and a chest radiograph should also be obtained. Two-dimensional echocardiography of the heart helps differentiate systolic from diastolic dysfunction. Coronary angiography is indicated in patients with heart failure and anginal chest pain and should be strongly considered in patients with an electrocardiogram suggestive of ischemia or myocardial infarction.

Q-sort assessment of attachment security during the preschool years: links from home to school

This study investigated relations among preschoolers' secure-base behavior with mother at home, stressful family conditions, and qualities of developing relationships with peers and teachers in preschool. Preschool-age children (N = 94; 51 boys and 43 girls) and their mothers were observed during multiple home visits, and their security of attachment was assessed with the Attachment Q-Set. Children in families with lower levels of stress had more secure attachment relationships with mothers. Both boys and girls who were less securely attached to their mothers expressed significantly more anger-aggression in preschool. For boys, higher levels of family stress were also significantly related to anger-aggression and to social competence in preschool. In addition, boys who were more securely attached to their mothers were more securely attached to their preschool teachers and were more popular with peers in preschool.

Precision measurement of cosmic-Ray antiproton spectrum

The energy spectrum of cosmic-ray antiprotons ( &pmacr;'s) has been measured in the range 0.18-3.56 GeV, based on 458 &pmacr;'s collected by BESS in a recent solar-minimum period. We have detected for the first time a characteristic peak at 2 GeV of &pmacr;'s originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoretical calculations, implying that the propagation models are basically correct and that different cosmic-ray species undergo a universal propagation. Future BESS data with still higher statistics will allow us to study the solar modulation and the propagation in detail and to search for primary &pmacr; components.

Sub-systems for optical frequency measurements: application to the 282-nm (199)Hg(+) transition and the 657-nm Ca line

We are developing laser frequency measurement technologies that should allow us to construct an optical frequency synthesis system capable of measuring optical frequencies with a precision limited by the atomic frequency standards. The system will be used to interconnect and compare new advanced optical-frequency references (such as Ca, Hg(+ ), and others) and eventually to connect these references to the Cs primary frequency standard. The approach we are taking is to subdivide optical frequency intervals into smaller and smaller pieces until we are able to use standard electronic-frequency-measurement technology to measure the smallest interval.

Quality attributes and storage stability of locally and mechanically extracted crude palm oils in selected communities in Rivers and Bayelsa states, Nigeria

The effect of different extraction methods on the quality of crude palm oil processed using traditional (local) and mechanical methods in selected areas of Rivers and Bayelsa States and their storage stability were investigated. Certain quality determining parameters such as free fatty acids (FFA), peroxide value (PV), saponification value (SV), moisture, impurities and volatile matter (MIV) content were determined prior to and after storage for three months. The free fatty acids (FFA) ranged from 7 to 19 percent, peroxide value (PV) ranged from 3 mEq/kg to 6 mEq/kg and moisture, impurity and volatile matter (MIV) ranged from 0.21 to 0.64 percent for locally extracted crude palm oil samples and mechanically extracted crude palm oil samples. There was no significant difference (p > 0.05) in the FFA of samples A and E before and after storage for 3 months. Also two of the locally extracted crude samples (A and E) stored better while one of the samples (D) showed a high level of deterioration as shown in its high levels of FFA, PV and IV values. Samples A and E resulted in a better quality of oil in terms of FFA (av. 7.25%) and PV (av. 4.5 meg/kg) when compared to the mechanically extracted one (sample C) with FFA (10.0%) and PV (5.78 mEq/kg). However, all the locally and mechanically extracted crude palm oil samples could not meet the industrial and international standard quality for crude palm with FFA (2-5%) and PV (2-3.5 mEq/kg). Among the three different storage containers used under different storage conditions, plastic containers (PC) resulted in a better storage stability of the crude palm oils in terms of FFA, SV, and IV than transparent bottles stored on shelves (TBS) and amber-colored bottles stored on the bare floor (BPF).

The relationship between rumination and eating disorders

OBJECTIVE

Rumination has been described as a symptom in association with eating disorders, but also as a separate disorder.

METHOD

A series of 8 female volunteers who reported rumination were systematically screened for the presence of eating disorders and other psychopathology.

RESULTS

Seven met current or prior criteria for an Axis I disorder and five had a current or prior eating disorder.

DISCUSSION

The importance of screening for eating disorders among women who ruminate, and for screening for rumination among eating disorder patients, is stressed.

Jejunostomy tube feedings should not be stopped in the perioperative patient

BACKGROUND

Anesthetic standard of care is to restrict oral intake for 8 hours before elective surgery. There is no research addressing appropriate preoperative discontinuation of jejunostomy tube (J-tube) feedings. We hypothesized that patients could be fed safely, via a J-tube, until the time of surgery.

METHODS

Patients admitted to a Level I Trauma Center, having J-tubes and undergoing a nonabdominal operation, were prospectively evaluated. Group I patients received J-tube feedings until transport to the operating room. Group II patients had tube feedings discontinued for at least 8 hours before surgery. Data were compared using the Student's t test and contingency table analysis.

RESULTS

There were 46 patients in group I and 36 in group II. There was no incidence of aspiration. Patient groups did not differ in age, mortality, length of stay, injury severity score, or ventilator days. Group I patients had tube feedings discontinued for fewer hours before and after surgery than group II patients (before surgery: 1.40 +/- 1.20 vs 11.61 +/- 5.01, respectively; p < .001; after surgery: 2.99 +/- 7.49 vs 7.11 +/- 9.03, respectively; p = .043); received more kilocalories/ grams of protein on the day of surgery (group I vs group II, 1676.15/89.57 +/- 1133.21/38.04 vs 791.14/57.58 +/-498.66/79.87, respectively; p = .001/p = .032) and more kilocalories/grams of protein on the first postoperative day (group I vs group II, 1580.74/92.57 +/- 600.53/37.96 vs 1152.47/63.53 +/- 733.96/39.40, respectively; p = .006/p = .001).

CONCLUSIONS

Patients receiving J-tubes who are undergoing nonabdominal operations may safely continue enteral nutrition at maximum protein and caloric intake until surgery.

Clinical characteristics of SOD1 gene mutations in UK families with ALS

Five to ten percent of patients with ALS have a family history of the disease, inheritance is usually autosomal dominant. Mutations of the SOD1 gene were first identified in a proportion of families with ALS by Rosen et al. The SOD1 gene encodes the enzyme copper zinc superoxide dismutase. Patients were studied from throughout the UK, where more than one individual in the family had ALS. Clinical history and examination of the individual and family were obtained, and DNA extracted from leukocytes of whole blood samples. Mutations were identified by standard sequencing methods. To date, 12 different mutations of SOD1 have been identified in 17 different families, representing around 20% of all ALS families studied. The mutations were mainly single base substitutions - H48Q, G72S, G93R, G93V, E100G, D101N, D101G, G108V, I113T, D125H, I149T - and also an insertion mutation - 132insTT - leading to a premature stop codon. The mutations were present in exons 2-5. We did not identify mutations in exon 1, although these have been identified by others in different patient samples. We have identified SOD1 mutations in around 20% of UK families with ALS studied. This is similar to that reported in other populations. Mutations have now been identified in all exons of SOD1. The individual mutations do not precisely predict disease severity, and generally it is difficult to give a specific prognosis based on the individuals' SOD1 mutations. We continue to investigate the possible pathogenic mechanisms of the SOD1 mutations. We have studied the neuropathology in patients with SOD1 mutations. We are also performing linkage studies to identify the genes involved in the 80% of families where an SOD1 mutation has not been identified.

Health-related quality of life: does rurality matter?

This study addresses the question of whether six health-related quality-of-life domains are related to population density within a rural area while adjusting for the effects of demographic characteristics and social support resources. The sample consisted of 2,178 adults aged 60 years or older who resided in eastern North Carolina between 1989 and 1991. Ordinary least squares regression estimation was used to analyze this survey data. For the analyses, rural residence was broken down into five levels reflecting population density, which was compared with analyses utilizing a collapsed dichotomous residential measure. Results indicate that a more detailed residence measure within a predominantly rural area provides valuable information that would otherwise be concealed by a dichotomous measure.

Nitrotyrosine formation in the airways and lung parenchyma of patients with asthma

BACKGROUND

Recent evidence has shown that nitric oxide (NO) levels are increased in asthmatic airways. Although the role of NO in asthma is unknown, reactive metabolites of NO may lead to nitrotyrosine formation and promote airway dysfunction.

OBJECTIVE

The aim of this study was to determine whether nitrotyrosine, as a marker of nitrating species, could be found in the airways and lung parenchyma of subjects with asthma who died of status asthmaticus or other nonrespiratory causes.

METHODS

Lung tissue specimens were obtained from 5 patients who died of status asthmaticus, 2 asthmatic patients who died of nonrespiratory causes, and 6 nonasthmatic control subjects who died of nonrespiratory causes. Lung sections were stained for immunofluorescence with use of an antinitrotyrosine antibody, followed by a indiocarbocyanine (Cy5, Jackson Immunochemicals, Westgrove, Pa)-conjugated secondary antibody.

RESULTS

Nonasthmatic lungs showed little or no nitrotyrosine staining, whereas asthmatic lungs demonstrated significantly more staining of nitrotyrosine residues distributed in both the airways and lung parenchyma.

CONCLUSION

This study demonstrates the presence of nitrotyrosine, and hence evidence of formation of nitrating species, in the airways and lung parenchyma of patients with asthma who died of status asthmaticus or other nonrespiratory causes. This finding supports the concept that widespread airway and parenchymal inflammation occurs in asthma, and, more specifically, that NO and its reactive metabolites may play a pathophysiologic role in asthma.

Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids

Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events.

Premature mortality in the United States: the roles of geographic area, socioeconomic status, household type, and availability of medical care

OBJECTIVES

This study examined premature mortality by county in the United States and assessed its association with metro/urban/rural geographic location, socioeconomic status, household type, and availability of medical care.

METHODS

Age-adjusted years of potential life lost before 75 years of age were calculated and mapped by county. Predictors of premature mortality were determined by multiple regression analysis.

RESULTS

Premature mortality was greatest in rural counties in the Southeast and Southwest. In a model predicting 55% of variation across counties, community structure factors explained more than availability of medical care. The proportions of female-headed households and Black populations were the strongest predictors, followed by variables measuring low education, American Indian population, and chronic unemployment. Greater availability of generalist physicians predicted fewer years of life lost in metropolitan counties but more in rural counties.

CONCLUSIONS

Community structure factors statistically explain much of the variation in premature mortality. The degree to which premature mortality is predicted by percentage of female-headed households is important for policy-making and delivery of medical care. The relationships described argue strongly for broadening the biomedical model.