Characteristics of socially isolated patients with coronary artery disease who are at elevated risk for mortality.

OBJECTIVES: Social isolation has been linked to poor survival in patients with coronary artery disease (CAD). Few studies have closely examined the psychosocial characteristics of CAD patients who lack social contact. METHODS: Social isolation was examined as a predictor of mortality in 430 patients with significant CAD. More isolated patients were compared with their less isolated counterparts on factors that might help explain the association between isolation and survival. RESULTS: The mortality rate was higher among isolated individuals. Those with three or fewer people in their social support network had a relative risk of 2.43 (p = .001) for cardiac mortality and 2.11 (p = .001) for all-cause mortality, controlling for age and disease severity. Adjustments for income, hostility, and smoking status did not alter the risk due to social isolation. With the exception of lower income, higher hostility ratings, and higher smoking rates, isolated patients did not differ from nonisolated patients on demographic indicators, disease severity, physical functioning, or psychological distress. Isolated patients reported less social support and were less pleased with the way they got along with network members, but they did not report less satisfaction with the amount of social contact received. CONCLUSIONS: Patients with small social networks had an elevated risk of mortality, but this greater risk was not attributable to confounding with disease severity, demographics, or psychological distress. These findings have implications for mechanisms linking social isolation to mortality and for the application of psychosocial interventions.

Solution structure of a type I dockerin domain, a novel prokaryotic, extracellular calcium-binding domain.

The type I dockerin domain is responsible for incorporating its associated glycosyl hydrolase into the bacterial cellulosome, a multienzyme cellulolytic complex, via its interaction with a receptor domain (cohesin domain) of the cellulosomal scaffolding subunit. The highly conserved dockerin domain is characterized by two Ca(2+)-binding sites with sequence similarity to the EF-hand motif. Here, we present the three-dimensional solution structure of the 69 residue dockerin domain of Clostridium thermocellum cellobiohydrolase CelS. Torsion angle dynamics calculations utilizing a total of 728 NOE-derived distance constraints and 79 torsion angle restraints yielded an ensemble of 20 structures with an average backbone r.m.s.d. for residues 5 to 29 and 32 to 66 of 0.54 A from the mean structure. The structure consists of two Ca(2+)-binding loop-helix motifs connected by a linker; the E helices entering each loop of the classical EF-hand motif are absent from the dockerin domain. Each dockerin Ca(2+)-binding subdomain is stabilized by a cluster of buried hydrophobic side-chains. Structural comparisons reveal that, in its non-complexed state, the dockerin fold displays a dramatic departure from that of Ca(2+)-bound EF-hand domains. A putative cohesin-binding surface, comprised of conserved hydrophobic and basic residues, is proposed, providing new insight into cellulosome assembly.

Secondary structure and calcium-induced folding of the Clostridium thermocellum dockerin domain determined by NMR spectroscopy.

Assembly of the cellulosome, a large, extracellular cellulase complex, depends upon docking of a myriad of enzymatic subunits to homologous receptors, or cohesin domains, arranged in tandem along a noncatalytic scaffolding protein. Docking to the cohesin domains is mediated by a highly conserved domain, dockerin (DS), borne by each enzymatic subunit. DS consists of two 22-amino-acid duplicated sequences, each bearing homology to the EF-hand calcium-binding loop. To compare the DS structure with that of the EF-hand helix-loop-helix motif, we analyzed the solution secondary structure of the DS from the cellobiohydrolase CelS subunit of the Clostridium thermocellum cellulosome using multidimensional heteronuclear NMR spectroscopy. The effect of Ca(2+)-binding on the DS structure was first investigated by using 2D (15)N-(1)H HSQC NMR spectroscopy. Changes in the spectra during Ca(2+) titration revealed that Ca(2+) induces folding of DS into its tertiary structure. This Ca(2+)-induced protein folding distinguishes DS from typical EF-hand-containing proteins. Sequential backbone assignments were determined for 63 of 69 residues. Analysis of the NOE connectivities and H(alpha) chemical shifts revealed that each half of the dockerin contains just one alpha-helix, comparable to the F-helix of the EF-hand motif. Thus, the structure of the DS Ca(2+)-binding subdomain deviates from that of the canonical EF-hand motif.

The relationship between self-rated health and health status among coronary artery patients.

OBJECTIVES: This study examined the descriptive relationship of self-rated health (SRH) with various psychosocial measures, sociodemographic variables, coronary artery disease (CAD) diagnostic/clinical measures, and medically abstracted comorbidities. METHODS: The sample was 2,855 individuals from the Mediators of Social Support (MOSS) study who had at least 75% narrowing in more than one vessel, as indicated by a cardiac catheterization. RESULTS: After adjusting for sociodemographic factors, individuals who rated their health as poor/fair had significantly worse performance on all psychosocial measures and were more likely to be female, non-White, and of a lower socioeconomic status than those who rated their health as being good or better. There were few differences on SRH across various diagnostic/clinical measures of health. DISCUSSION: A single item measure of SRH may be useful; the generalizability of the item must be considered. In this sample of CAD patients, SRH was related more to psychosocial factors than to clinical and disease indicators.

Construction and characterization of a 1,3-propanediol operon.

The genes for the production of 1,3-propanediol (1,3-PD) in Klebsiella pneumoniae, dhaB, which encodes glycerol dehydratase, and dhaT, which encodes 1,3-PD oxidoreductase, are naturally under the control of two different promoters and are transcribed in different directions. These genes were reconfigured into an operon containing dhaB followed by dhaT under the control of a single promoter. The operon contains unique restriction sites to facilitate replacement of the promoter and other modifications. In a fed-batch cofermentation of glycerol and glucose. Escherichia coli containing the operon consumed 9.3 g of glycerol per liter and produced 6.3 g of 1,3-PD per liter. The fermentation had two distinct phases. In the first phase, significant cell growth occurred and the products were mainly 1,3-PD and acetate. In the second phase, very little growth occurred and the main products were 1,3-PD and pyruvate. The first enzyme in the 1,3-PD pathway, glycerol dehydratase, requires coenzyme B12, which must be provided in E. coli fermentations. However, the amount of coenzyme B12 needed was quite small, with 10 nM sufficient for good 1,3-PD production in batch cofermentations. 1,3-PD is a useful intermediate in the production of polyesters. The 1,3-PD operon was designed so that it can be readily modified for expression in other prokaryotic hosts; therefore, it is useful for metabolic engineering of 1,3-PD pathways from glycerol and other substrates such as glucose.

Self-efficacy and adjustment in cancer patients: a preliminary report.

The relation between cancer self-efficacy and patient cancer adjustment, depression, psychological distress, and behavioral dysfunction in 42 cancer patients was studied in a preliminary investigation. Participants were male cancer outpatients recruited from a Veterans Administration Medical Center who completed a Cancer Self-Efficacy Scale, the Center for Epidemiological Studies-Depression Scale, the Affect Balance Scale, and the Sickness Impact Profile. Correlational analyses indicated that self-efficacy was related to all adjustment measures. Regression analyses revealed that when age, education, time since initial diagnosis, and current disease status were controlled, the relationships between patient self-efficacy expectations and cancer adjustment, psychological distress, negative affect, positive affect, and behavioral dysfunction remained statistically significant. Taken together, the results of the analyses suggested that patient expectancies about control over cancer-related symptoms were related to several important aspects of patient functioning. The results underscored the need for further investigation of this construct in cancer patients.

Minnesota Multiphasic Personality Inventory profiles of Vietnam combat veterans with posttraumatic stress disorder and their children.

Forty children of 28 fathers who are Vietnam veterans with posttraumatic stress disorder (PTSD) completed the Minnesota Multiphasic Personality Inventory. Each of the fathers had at least one elevated clinical scale. Fathers averaged eight elevated clinical scales, and compared to more recent norms, fathers averaged seven elevated clinical scales. Seventy-eight percent of the children had at least one clinically elevated scale (averaging three elevated clinical scales). Compared to contemporary normal adolescents and adults, 65% of children had at least one clinically elevated scale (still averaging three elevated clinical scales). No consistent MMPI profile patterns emerged within or across the two groups. No gender differences were detected among child MMPI profiles. Forty percent of the children reported illegal drug use, and 35% reported behavior problems. Fifteen percent of children reported previous violent behavior. Eighty-three percent of the children reported elevated Cook-Medley hostility scores as compared to an age-matched national normative sample. Children with higher PK scores were also significantly more likely to report higher Cook-Medley hostility scores. Forty-five percent of children reported significant elevations on the PTSD/PK subscales.

Caregiver burden in partners of Vietnam War veterans with posttraumatic stress disorder.

Caregiver burden in 58 partners of Vietnam veterans with posttraumatic stress disorder (PTSD) was examined. The relationship between patient PTSD severity and caregiver burden, as well as the effect of several caregiver and patient variables on caregiver psychological status, was evaluated twice, an average of 8 months apart. Patient symptom severity was positively correlated with caregiver burden. Time 1 cross-sectional analysis indicated that greater caregiver burden was associated with greater caregiver psychological distress, dysphoria, and anxiety. Patient symptom severity also contributed to caregiver psychological distress; financial stress contributed to caregiver dysphoria and trait anxiety. Time 2 cross-sectional analyses essentially replicated the Time 1 findings. A third set of analyses examining change scores indicated that changes in caregiver burden for individuals in the sample positively predicted individual changes in caregiver psychological distress, dysphoria, and state anxiety.

Smoking withdrawal symptoms in response to a trauma-related stressor among Vietnam combat veterans with posttraumatic stress disorder.

This study investigated the relationship between a trauma-related stressor and smoking withdrawal symptoms in 25 male Vietnam combat veterans with posttraumatic stress disorder (PTSD) using a within-subjects design. All subjects were smokers. The stressor involved a modified Stroop task, in which the veterans color-named either anxiety-related or neutral control words. Anxiety-related words produced more withdrawal symptoms than neutral control words, including increased craving, negative affect symptoms, somatic symptoms, and lack of alertness.