Biomedical subjects
Publications and source records attributed to R E Roberts.
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An 8-item loneliness scale was administered to a sample of high school students (N = 1,710) twice, about one year apart. The scale exhibited good internal consistency reliability (alphas of 0.78 and 0.79, respectively), was relatively independent of gender effects, and demonstrated evidence of construct validity. Factor analysis of the items yielded a two-factor solution which met methodological criteria, but over-all the data suggested a method artifact, e.g., positively and negatively worded items factored separately. Examination of the two factors indicated the subscale of four negative items (lack companionship, no longer close, left out, feel isolated) had an alpha reliability of .77, correlated .89 with the total scale score, and exhibited virtually an identical pattern of associations with a set of theoretically relevant variables as the full scale. This four-item scale may be useful in epidemiologic surveys in which over-all response burden is an issue.
In preparation for a community-based study of depression in adolescence, several point studies were conducted with samples of adolescents. The purpose of these studies was to evaluate the reliability and association with depression of several instruments when used with older (14- to 18-year-old) adolescents. These instruments included measures of cognitions, body image, self-esteem, self-awareness, social interactions with peers and family, social support, micro- and macrostressful life events, anxiety and tension, positive affect, antisocial or oppositional behaviour, suicidal ideation, and vocabulary. The internal consistency reliability and stability of most of the instruments were satisfactory. In addition, most instruments were associated with a measure of depression, Radloff's Center for Epidemiological Studies-Depression Scale. Several of the scales were successfully abbreviated using techniques based on factor analysis and item analysis.
The purpose of this research was to investigate differential manifestation of depressive symptomatology among adolescents from diverse ethnocultural groups. Data from a national survey of persons 12 to 17 years of age (N = 2200) were analyzed, comparing responses of Anglo, African, Mexican, and other Hispanic Americans with a 12-item version of the Center for Epidemiologic Studies Depression Scale. The results indicated minimal differences in terms of item response and internal consistency-reliability among the four adolescent groups. However, there were differences in patterns of item endorsement, as indicated by principal component factor analysis. Anglo- and African Americans exhibited similar factor structure, represented by negative affect, positive affect, and psychosomatic symptoms. The two Hispanic groups also exhibited a three-dimensional pattern, but there was a tendency among Hispanic adolescents for somatic symptoms and negative affect symptoms to cluster together. This pattern may indicate a more prominent role of somatic complaints in the presentation of depression among Mexican Americans and other Hispanics.
The relation between level of physical activity and risk of subsequent depression was examined using three waves of data from the Alameda County Study. Among subjects who were not depressed at baseline, those who reported a low activity level were at significantly greater risk for depression at the 1974 follow-up than were those who reported high levels of activity at baseline. Adjustments for physical health, socioeconomic status, life events, social supports, and other health habits did not affect the association appreciably. Associations between 1965-1974 changes in activity level and depression in the 1983 follow-up suggest that the risk of depression can be altered by changes in exercise habits, although these associations were not statistically significant after adjustment for covariates. These results provide somewhat stronger evidence for an activity-depression link than do previous studies, and they argue for the inclusion of exercise programs as part of community mental health programs, as well as for further studies that focus on the relation between life-style and mental health.
This study examines a multifactorial model of caregiving strain and its effects in a sample of 341 employed caregivers, using a LISREL framework to estimate path coefficients. Work disruptions associated with caregiving significantly affected caregiving strain and the perceived likelihood of job termination. Work interference was in turn affected by the care recipient's level of impairment and the perceived adequacy of the support received. Respondents with more flexible job responsibilities reported lower levels of work interference than did other respondents.
The ability of two depression scales, the Center for Epidemiologic Studies Depression Scale (CES-D) and the Beck Depression Inventory (BDI), to identify cases of DSM-III-R major depression and dysthymia was investigated in a large, community sample of high school students. Receiver operating characteristics analyses indicated that different caseness criteria should be used for boys and girls for both the CES-D and the BDI. Internal consistency-reliability and sensitivity and specificity for detecting current episodes of current depression and dysthymia were adequate and comparable to those found with adult samples, but both the CES-D and the BDI generated many false positives. Multiple screening using the "serial" strategy increased positive predictive power substantially for both the CES-D and the BDI, whereas using the "parallel" strategy had very little effect on the efficacy of the two screeners. The results indicate that neither the BDI nor the CES-D should be used by themselves as methods for case ascertainment in either epidemiological or experimental studies, although the BDI does function somewhat better than the CES-D as a screener.
The purpose of this report is to present data on the effects of language (English/Spanish) and ethnic status (white/non-Hispanic or Mexican origin) on the ability of the Center for Epidemiologic Studies Depression (CES-D) scale to detect cases of clinical depression and generalized anxiety identified using the Diagnostic Interview Schedule (DIS) in psychiatric treatment settings. The agreement between the CES-D scale and the DIS diagnoses of major depressive disorder (MDD) and generalized anxiety disorder (GAD) was poor, especially among Mexican-origin patients interviewed in Spanish. Multiple regression analysis revealed that the CES-D scale was positively associated with MDD in all groups. In addition, GAD also was associated with the CES-D scale in Anglos and English-speaking Mexican-Americans but not in Spanish-speaking Mexican-Americans.
The relationship between psychological distress, in this case depression, and subsequent risk of mortality is examined using data from the Alameda County (California) Study, an 18-yr, three-wave prospective investigation of psychosocial risk factors and health. The results indicate no relationship between psychological morbidity and all-cause mortality or specific causes of death. While these results are discordant with those reported from a majority of studies of psychiatric patients, they are concordant with a majority of community-based studies of the general adult population. Possible methodologic explanations are discussed which might account for disparate results reported to date, in particular failure to control for the effects of co-morbidity of somatic disorders and socioeconomic status.
Results from a second empirical test of a theory of intergenerational family relations, as an example of empirically driven theory construction in social gerontology, are presented. The theory we tested reflects an attempt to explain later-life patterns of affection, association, and consensus between parents and children as interdependent components of a meta-construct--family intergenerational solidarity. The theoretical model also identifies variables that are expected to predict variations in levels of solidarity. A recent empirical test (Atkinson, Kivett, and Campbell, 1986) offered little support for the central proposition of the model: that solidarity can be indexed by a linear-additive composite of affection, association, and consensus. The replication analysis reported here is based on a different sample, as well as alternate measures and statistical methods. The convergent results suggest that (a) later-life intergenerational solidarity is not a unidimensional construct, and (b) different variables predict each component. This exercise of theory statement, testing, and retesting leads us to suggest several refinements to the theory acknowledging a more complex relationship between dimensions of intergenerational relations in old age.
In Escherichia coli, FNR and CRP are homologous transcriptional regulators which recognize similar nucleotide sequences via DNA-binding domains containing analogous helix-turn-helix motifs. The molecular basis for recognition and discrimination of their target sites has been investigated by directed amino acid substitutions in the corresponding DNA-recognition helices. In FNR, Glu-209 and Ser-212 are essential residues for the recognition of FNR sites. A V208R substitution confers CRP-site specificity without loss of FNR specificity, but this has adverse effects on anaerobic growth. In contrast, changes at two (V208R and E209D) or three (V208R, S212G and G216K) positions in FNR endow a single CRP-site binding specificity. In reciprocal experiments, two substitutions (R180V and G184S) were required to convert the binding specificity of CRP to that of FNR. Altering Asp-199 in FNR failed to produce a positive control phenotype, unlike substitutions at the comparable site in CRP. Implications for the mechanism of sequence discrimination by FNR and CRP are discussed.
Data from 562 psychiatric patients were analyzed to assess the effects of ethnic status (Anglo/Mexican origin) and language (English/Spanish) on the reliability and validity of the Center for Epidemiologic Studies-Depression Scale. The results indicate no systematic variation in either reliability (test-retest, internal consistency), dimensionality, or ability of the CES-D Scale to detect clinical depression among Anglos or persons of Mexican origin classified according to language use as Spanish dominant, English dominant, or bilingual. However, the data indicate that this particular screening instrument does not adequately discriminate between patients with clinical depression and those without depression. These results corroborate several recent studies that question the utility of the CES-D Scale as a depression screening instrument. Taken together, the available evidence suggests that the ability of the CES-D Scale to detect major depression is so limited that further use of the instrument as a screening scale would seem unwarranted, at least in treatment settings.
The ndh gene of Escherichia coli which encodes an NADH dehydrogenase contains a putative FNR-binding site in its upstream non-coding region, and its expression has been investigated using an ndh-lacZ fusion. Expression of the fusion was found to be reduced during anaerobic growth, and experiments with hosts containing an fnr mutation and/or a multicopy fnr+ plasmid indicated that the anaerobic repression of the ndh gene is mediated by the FNR protein. Thus FNR can function as an anaerobic repressor as well as an anaerobic transcriptional activator. The results are consistent with the FNR-binding function attributed to the proposed consensus sequence. Using frdA- and ndh-lacZ fusions exhibiting positive and negative regulation by FNR, it was further shown that the depletion of metal ions in growth media with chelating agents mimics oxygen with respect to the activity of FNR. Possible roles for metal ions in the oxygen-sensing pathway associated with FNR function are discussed.
During a 6-month period, 108 sexually mature stray cats were euthanatized at a humane shelter in Alabama. Aelurostrongylus abstrusus was identified in 20 of the cats (18.5%) by Baermann fecal examination, necropsy, or histologic examination. The Baermann fecal examination was a more sensitive test for aelurostrongylosis than was necropsy or histologic examination. Thoracic radiography was useful in identifying infected cats, but was a less sensitive and more nonspecific method of detection than was the fecal examination. Changes in CBC and serum protein concentrations were not helpful identifying cats with aelurostrongylosis. Six of 17 (35%) heartworm-free, lungworm-infected cats had antibodies to Dirofilaria immitis, as determined by an ELISA method, but none had circulating D immitis antigen, as determined by an ELISA method. Three (2.8%) cats had D immitis. Two of the heartworm-infected cats had no detectable antemortem radiographic or clinicopathologic evidence of the infection. Results of ELISA were positive for antibodies to adult heartworms in 2 cats and for circulating heartworm antigen in 2 cats. One cat that had only one heartworm had no detectable circulating heartworm antigen.
The guaC (GMP reductase), nadC (quinolinate phosphoribosyltransferase), and aroP (aromatic amino acid permease) genes of Escherichia coli K-12 were located in the 2.5-min region of the chromosome (muT-guaC-nadC-aroP-aceE) by a combination of linkage analysis, deletion mapping, restriction analysis, and plasmid subcloning. The guaC locus expressed a product of Mr 37,000 with a clockwise transcriptional polarity, and the GMP reductase activities of guaC+ plasmid-containing strains were amplified 15- to 20-fold.
The association between status attributes, personal resources, life stress, physical health, and occurrence of depressive symptoms nine years later was assessed by the 1965 Human Population Laboratory survey of a random sample of 6,928 adults in Alameda County, California, and by a subsequent follow-up survey in 1974. In multiple logistic analyses, depressive symptoms at baseline, low education, physical disability or presence of chronic conditions, poor perceived health, personal uncertainty, residential move, job loss, money problems, anomy, and social isolation were independently associated with increased risk of depressive symptoms at the nine-year follow-up. Age, low income, ethnicity, marital status, separation or divorce, and health practices at baseline were unrelated to depressive symptoms. These results underscore both the multifactorial nature of depression and the importance of prospective analyses of depressive phenomena.
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The nucleotide sequences of two segments of DNA (2250 and 2921 base-pairs) containing the functionally related fumarase (fumC) and aspartase (aspA) genes of Escherichia coli K12 were determined. The fumC structural gene comprises 1398 base-pairs (466 codons, excluding the initiation codon), and it encodes a polypeptide of Mr 50353 that resembles the fumarases of Bacillus subtilis 168 (citG-gene product), rat liver and pig heart. The fumC gene starts 140 base-pairs downstream of the structurally-unrelated fumA gene, but there is no evidence that both genes form part of the same operon. The aspA structural gene comprises 1431 base-pairs (477 codons excluding the initiation codon), and it encodes a polypeptide of Mr 52190, similar to that predicted from maxicell studies and for the enzyme from E. coli W. Remarkable homologies were found between the primary structures of the fumarase (fumC and citG) and aspartase (aspA) genes and their products, suggesting close structural and evolutionary relationships.