Biomedical subjects

J M Neuhaus

Publications and source records attributed to J M Neuhaus.

At least 19 recordsLinked to original sources

PubMed1999

Persistent stress as a predictor of genital herpes recurrence.

BACKGROUND: Results of several studies suggest that psychological stress and negative mood can trigger genital herpes recurrences, but results are inconsistent. OBJECTIVE: To determine whether short-term or persistent psychological stress or specific negative moods are predictive of genital herpes recurrences in women. METHODS: A prospective cohort study followed up participants for 6 months using weekly assessments of stress and mood, monthly assessments of life change events, and diary reports of genital herpes recurrences confirmed by medical examination when feasible. The community sample consisted of 58 women, aged 20 to 44 years, with a 1- to 10-year history of visible genital herpes recurrence and at least 1 recurrence in the previous 6 months. RESULTS: Persistent stress predicted recurrence in the subsequent week (odds ratio, 1.08 per unit increase in stress; 95% confidence interval, 1.01-1.15; P=.03). After adjusting for recurrence in the previous week, the more weekly persistent stress reported, the greater the likelihood of recurrence the following week. Also, an increased recurrence rate occurred after the month during which participants experienced their highest levels of anxiety (P =.03). There were no significant associations between recurrence and short-term stress, life events, depressive mood, anger, or phase of menstrual cycle. CONCLUSIONS: Persistent stressors and highest level of anxiety predicted genital herpes recurrence, whereas transient mood states, short-term stressors, and life change events did not. Women with herpes can be reassured that short-term stressful life experiences and dysphoric mood states do not put them at risk for increased outbreaks of recurrent genital herpes.

Adult↗

PubMed1999

Effect of receptive oral sex and smoking on the incidence of hairy leukoplakia in HIV-positive gay men.

We sought to determine whether hairy leukoplakia (HL), an Epstein-Barr virus-related oral lesion, is associated with receptive oral sex activity and cigarette smoking among HIV-positive gay men. Oral examinations were conducted every 6 months among San Francisco Men's Health Study participants over a 6-year period. We fitted time-to-lesion regression models to compare the incidence of HL among men who had mouth-to-penis contact with various numbers of partners, while controlling for cigarette smoking and CD4 count. The 6-year incidence of HL was 32% among 291 HIV-positive men. We found no significant increase in the hazard of developing HL for each additional insertive-oral-sex male partner in the past 6 months (relative hazard = 1.01; 95% confidence interval [CI], 0.99, 1.02), and a similar lack of association when number of sex partners was categorized. However, the hazard of developing HL doubled with any 300-unit decrease in CD4 count (95% CI, 1.4, 2.7), or if men smoked > or =20 cigarettes/day compared with nonsmokers (95% CI, 1.2, 3.9). This finding, which may suggest one effect that smoking produces on the oral mucosa's local immune response, merits further investigation.

Adult↗

PubMed1999

Differential immune system changes with acute and persistent stress for optimists vs pessimists.

This study investigated whether acute and persistent stressors and life change events were followed by changes in immune status, and whether dispositional optimism moderated these relationships. Thirty-nine healthy women ages 18-45 were followed prospectively for 3 months, with weekly assessment of acute and persistent stressors and monthly assessment of life events and immune parameters (NK cell cytotoxicity, and CD4 and CD8 T cell subsets). The study used an autoregressive linear model to examine how weekly appraised acute and persistent stress levels were associated with immune parameters in the subsequent week. Analyses revealed that the immune outcomes were differentially affected by acute and persistent stressors. Further, the association between acute stress and subsequent immune parameters was buffered by an optimistic perspective. However, when stress persisted at high levels, optimists showed more subsequent immune decrements than pessimists.

Acute Disease↗

PubMed1999

Subcellular localization and in vivo identification of the putative movement protein of olive latent virus 2.

The gene encoding the 36.5 kDa ('36K') nonstructural protein located on RNA3 of olive latent virus 2 (OLV-2) was cloned, expressed with the Escherichia coli pGEX-2T system and the purified protein used to raise a polyclonal antiserum. Immunoblot analysis of OLV-2-infected Nicotiana benthamiana plants showed that the 36K protein accumulated in the early stages of infection and was associated with a subcellular fraction enriched in cytoplasmic membranes. In infected cells there were tubular structures, some containing virus-like particles, scattered in the cytoplasm or protruding from or penetrating the cell wall at the plasmodesmata. Immunogold labelling localized the 36K protein in the plasmodesmata of OLV-2-infected cells and showed it to be associated with virus-containing tubules. Leaf trichome cells of N. tabacum plants, transformed with a 36K-green fluorescent protein (GFP) fusion construct, revealed localized fluorescence in the cell walls, possibly due to association of the fusion protein with plasmodesmata. When the same 36K-GFP fusion protein was expressed in N. tabacum protoplasts, long tubular fluorescent structures protruded from the protoplast surface, suggesting that the 36K protein is responsible for tubule induction. The conclusion is drawn that this protein is likely to be the OLV-2 movement protein, mediating cell-to-cell virus movement, and that movement is by a tubule-guided mechanism.

Bromoviridae↗

PubMed1999

Dental care access and use among HIV-infected women.

OBJECTIVES: This study sought to identify predictors of dental care use in HIV-infected women. METHODS: In a cross-sectional survey of HIV-infected women enrolled in the northern California site of the Women's Interagency HIV Study, dental care use and unmet need were assessed in relation to selected variables. RESULTS: Among 213 respondents, who were predominantly Black and younger than 45 years, 43% had not seen a dentist and 53% (among dentate women) reported no dental cleaning in more than a year (although 67% had dental insurance coverage, mainly state Medicaid). Nine percent were edentulous. Among nonusers of dental care, 78% reported that they wanted care but failed to get it. Barriers included fear of and discomfort with dentists, not getting around to making an appointment, and not knowing which dentist to visit. Multivariate analysis showed that lack of past-year dental care was associated mainly with unemployment, a perception of poor oral health, and edentulism. CONCLUSIONS: HIV-positive women appear to be underusing dental care services. Fear and lack of information regarding available resources, in addition to unemployment and perception of poor oral health, may be important barriers.

Adult↗

PubMed1998

Specific accumulation of GFP in a non-acidic vacuolar compartment via a C-terminal propeptide-mediated sorting pathway.

The green fluorescent protein (GFP) from Aequorea victoria can be detected in living plant cells after transient transformation of protoplasts. Expression of the GFP can be used to monitor protein trafficking in a mixed cell population and also to study the different function and importance of organelles in different cell types. We developed a vacuolar form of GFP that was obtained by replacing the C-terminal endoplasmic reticulum (ER)-retention motif of mGFP5-ER by the vacuolar targeting peptide of tobacco chitinase A. The vacuolar GFP was transported and accumulated in the vacuole as expected. However, we found two patterns of GFP accumulation after prolonged incubation (18-24 h) depending on the cell type. Most chloroplast-rich protoplasts had a fluorescent large central vacuole. In contrast, most chloroplast-poor protoplasts accumulated the GFP in one smaller vacuole but not in the large central vacuole, which was visible under a light microscope in the same cell. This differential accumulation reflected the existence of two different vacuolar compartments as described recently by immunolocalization of several vacuolar markers. We were able to characterize the vacuolar compartment to which GFP is specifically targeted as non-acidic, since it did not accumulate neutral red while acidic vacuoles did not accumulate GFP.

Androstadienes↗

PubMed1998

Between- and within-cluster covariate effects in the analysis of clustered data.

Standard methods for the regression analysis of clustered data postulate models relating covariates to the response without regard to between- and within-cluster covariate effects. Implicit in these analyses is the assumption that these effects are identical. Example data show that this is frequently not the case and that analyses that ignore differential between- and within-cluster covariate effects can be misleading. Consideration of between- and within-cluster effects also helps to explain observed and theoretical differences between mixture model analyses and those based on conditional likelihood methods. In particular, we show that conditional likelihood methods estimate purely within-cluster covariate effects, whereas mixture model approaches estimate a weighted average of between- and within-cluster covariate effects.

Adolescent↗

PubMed1998

Sorting of proteins to vacuoles in plant cells.

An individual plant cell may contain at least two functionally and structurally distinct types of vacuoles: protein storage vacuoles and lytic vacuoles. Presumably a cell that stores proteins in vacuoles must maintain these separate compartments to prevent exposure of the storage proteins to an acidified environment with active hydrolytic enzymes where they would be degraded. Thus, the organization of the secretory pathway in plant cells, which includes the vacuoles, has a fascinating complexity not anticipated from the extensive genetic and biochemical studies of the secretory pathway in yeast. Plant cells must generate the membranes to form two separate types of tonoplast, maintain them as separate organelles, and direct soluble proteins from the secretory flow specifically to one or the other via separate vesicular pathways. Individual soluble and membrane proteins must be recognized and sorted into one or the other pathway by distinct, specific mechanisms. Here we review the emerging picture of how separate plant vacuoles are organized structurally and how proteins are recognized and sorted to each type.

Amino Acid Sequence↗

PubMed1997

Expression of beta-1,3-glucanase and chitinase in healthy, stem-rust-affected and elicitor-treated near-isogenic wheat lines showing Sr5-or Sr24-specified race-specific rust resistance.

Pathogenesis-related expression of the two antifungal hydrolases beta-1,3-glucanase (EC 3.2.1.39) and chitinase (EC 3.2.1.14) was studied in wheat (Triticum aestivum L.) as part of the defence response to stem rust (Puccinia graminis f.sp. tritici, Pgt), mediated by the semi-dominantly acting resistance genes Sr5 and Sr24. Complete resistance (infection type 0), mediated by the Sr5 gene in cultivar Pre-Sr5, closely correlates with the hypersensitive response of penetrated cells at early stage of the interaction, when the first haustorium is formed. In contrast, cultivar Pre-Sr24 shows intermediate resistance (infection type 2-3) which is not directly linked to cell death. In both cases, the plant response included a rapid increase in beta-1,3-glucanase activity between 24 and 48 h after inoculation. One main extracellular 30-kDa isform of beta-1,3-glucanase was present in both lines, as shown by polyacrylamide-gel electrophoresis. Two additional minor isoforms (32 and 23 kDa) were detected only in Pre-Sr24, and only at later time points. Increased enzme activity and the appearance of new isoforms in the resistance lines was preceded by accumulation of mRNAs encoding beta-1,3-glucanase and chitinases. However, there were no changes in chitinase activity or isoforms. A high constitutive level of chitinase activity was observed in all wheat genotypes. Serological studies indicated the presence of a class II chitinase of 26 kDa. Accumulation of beta-1,3-glucanase and chitinase transcripts was detected before the pathogen penetrated the leaves through stomata and approximately 16 h before the typical hypersensitive response was observed, indicating that signal(s) for defense gene activation were recognised by the host plant long before a tight contact between the pathogen and a host cell is established. A glycoprotein (Pgt elicitor) derived from hyphal walls, strongly induced beta-1,3-glucanase. We discuss the possible role of the elicitor in the early signalling mediating Sr5- and Sr24-specified resistance in wheat.

Amino Acid Sequence↗

PubMed1997

Dependence estimation for marginal models of multivariate survival data.

We have previously (Segal and Neuhaus, 1993) devised methods for obtaining marginal regression coefficients and associated variance estimates for multivariate survival data, using a synthesis of the Poisson regression formulation for univariate censored survival analysis and generalized estimating equations (GEE's). The method is parametric in that a baseline survival distribution is specified. Analogous semiparametric models, with unspecified baseline survival, have also been developed (Wei, Lin and Weissfeld, 1989; Lin, 1994). Common to both these approaches is the provision of robust variances for the regression parameters. However, none of this work has addressed the more difficult area of dependence estimation. While GEE approaches ostensibly provide such estimates, we show that there are problems adopting these with multivariate survival data. Further, we demonstrate that these problems can affect estimation of the regression coefficients themselves. An alternate, ad hoc approach to dependence estimation, based on design effects, is proposed and evaluated via simulation and illustrative examples.

Algorithms↗

PubMed1997

Living arrangements, changes in living arrangements, and survival among community dwelling older adults.

OBJECTIVES: This study examines whether living arrangements and changes in living arrangements are associated with survival among older community-dwelling adults, and whether differences in health status account for observed differences in survival. METHODS: The sample consisted of 5085 persons aged 70 years or older who had participated in the Longitudinal Study of Aging in 1984 and 1986. Proportional hazards models were used to examine associations of survival time through 1990 with living arrangements in 1984 and with changes in living arrangements from 1984 to 1986. RESULTS: Women who lived with someone other than a spouse at baseline or who changed from living with a spouse to living with someone other than a spouse were at greater risk of dying than women in other living arrangements, independent of health status or functioning. Among men, survival time was not generally associated with baseline living arrangements. CONCLUSIONS: Older adults who live alone or who change from living with someone to living alone do not have an increased mortality risk. However, living with or changing to living with someone other than a spouse may be associated with increased mortality risk.

Activities of Daily Living↗

PubMed1997

Variation among rheumatologists in clinical outcomes and frequency of office visits for rheumatoid arthritis.

OBJECTIVE: To estimate the variation among rheumatologists in clinical outcomes and frequency of office visits for patients with rheumatoid arthritis (RA), after accounting for patient demographic and clinical characteristics and treatments prescribed. METHODS: Multiple regression analysis using random effects for rheumatologists and adjustments for patient characteristics and treatments received, based on data derived from a panel study of persons with RA. RESULTS: During the years 1984-1993, rheumatologists accounted for a moderate amount of the total variation in clinical outcomes and nearly one-third of the total variation in frequency of office visits. For example, in 1993 rheumatologist associated variation in 4 clinical outcomes ranged from 16 to 25%, while the variation in office visit frequency attributable to rheumatologists stood at 46% of the total variation. However, rheumatologist associated variation in clinical outcomes was not statistically significant in any year, while variation in office visits was highly significant in all years (p < or = 0.0001). Although there was an increase in the percentage of variation attributable to rheumatologists for all outcomes examined across the years of this study, the time trend reached statistical significance only for frequency of office visits (2.4% per year; p = 0.0135) and functional status (1.6% per year; p = 0.0034). CONCLUSION: The magnitude and strength of rheumatologist associated variation in frequency of office visits, without comparable strength in the variation in clinical outcomes, may suggest inefficiencies in the use of resources for the care of persons with RA. Further work is needed to directly examine the relationship between health outcomes and resource utilization.

Adult↗

PubMed1996

Human immunodeficiency virus-related oral manifestations and gender. A longitudinal analysis. The University of California, San Francisco Oral AIDS Center Epidemiology Collaborative Group.

BACKGROUND: Because human immunodeficiency virus (HIV) infection affects an increasing number of women in the United States, we investigated the role played by gender in the occurrence of HIV-related oral conditions. METHODS: As part of a 4-year prospective study of 3 epidemiological cohorts, oral and physical examinations (including blood tests) were performed on HIV-infected men (n = 200) and women (n = 218) at 6-month intervals. Our outcome variables included oral conditions commonly associated with HIV infection: hairy leukoplakia, candidiasis, ulcers, warts, non-Hodgkin lymphoma, Kaposi sarcoma, and parotid enlargement. RESULTS: Only hairy leukoplakia, candidiasis, and ulcers were observed. The occurrence of hairy leukoplakia and candidiasis was higher in men (22% and 24%, respectively) than in women (9% and 13%, respectively) during the study period. A regression model for longitudinal data (generalized estimating equation) disclosed that the odds of having hairy leukoplakia were 2.5 times higher for men than for women, after controlling for CD4+ cell count, race, and injecting drug use (95% confidence interval, 1.34-4.76; P = .003). Length of follow-up did not confound this association. A weaker association was found between the occurrence of oral candidiasis and gender (adjusted odds ratio, 1.85; 95% confidence interval, 1.0-3.43; P = .05). CONCLUSIONS: In this sample of HIV-infected adults, we found that men were significantly more likely to have hairy leukoplakia than were women. The hairy leukoplakia-gender association merits further investigation, because it may be related to a gender difference in the mode of expression of Epstein-Barr virus.

Adult↗

PubMed1996

Plant chitinases use two different hydrolytic mechanisms.

Bacterial, fungal, animal, and some plant chitinases form family 18 of glycosyl hydrolases. Most plant chitinases form the family 19. While some chitinases also have lysozyme activity, animal lysozymes belong to different families. For glycosyl hydrolases, two reaction mechanisms are possible, leading to either retention or inversion of the anomeric configuration. We analyzed by HPLC the stereochemical outcome of the hydrolysis catalyzed by cucumber and bean chitinases, belonging to families 18 and 19, respectively. Cucumber chitinase used the retaining mechanism as known for bacterial chitinases and hen egg white lysozyme for which the mechanism has been determined. In contrast, bean chitinase catalyzed the hydrolysis of chitooligosaccharides with overall inversion of anomeric configuration.

Catalysis↗

PubMed1995

Serum fatty acids and the risk of coronary heart disease.

To examine the relation between serum fatty acids and coronary heart disease (CHD), the authors conducted a nested case-control study of 94 men with incident CHD and 94 men without incident CHD who were enrolled in the Usual Care group of the Multiple Risk Factor Intervention Trial between December 1973 and February 1976. After confirming the stability of the stored serum samples, the authors measured serum fatty acid levels by gas-liquid chromatography and examined their association with CHD. In all multivariate models, levels of the cholesterol ester saturated fatty acid palmitic acid (16:0) were directly associated with CHD risk (standardized odds ratio = 1.68; 95% confidence interval 1.10-2.55 in the model that adjusted for total plasma cholesterol level). Levels of the phospholipid omega-3 fatty acid docosapentaenoic acid (22:5) were inversely associated with CHD risk in the two multivariate models that controlled for the effects of total plasma cholesterol level or high density lipoprotein cholesterol to total plasma cholesterol ratio (standardized odds ratio = 0.58; 95% confidence interval 0.38-0.89 in the first model that controlled for total plasma cholesterol level). In contrast to the first two multivariate models, levels of the docosahexaenoic acid (22:6) were inversely associated with CHD risk in a third multivariate model that controlled for the effects of high density lipoprotein cholesterol to low density lipoprotein cholesterol ratio (standardized odds ratio = 0.57; 95% confidence interval 0.36-0.90). These findings are consistent with other evidence indicating that saturated fatty acids are directly correlated with CHD and that omega-3 polyunsaturated fatty acids are inversely correlated with CHD. Because these associations were present after adjustment for blood lipid levels, other mechanisms, such as a direct effect on blood clotting, may be involved.

Adult↗

PubMed1994

Health behaviors and survival among middle-aged and older men and women in the NHANES I Epidemiologic Follow-up Study.

BACKGROUND: Since the 1960s there has been a decline in mortality rates for older U.S. adults, suggesting the importance of examining the role of prevention and health promotion in improving the health and survival of older adults. Epidemiologic studies of age and gender differences in the impact of health behaviors on survival for older U.S. adults are needed to provide information for intervention and health promotion efforts for older Americans. METHODS: We examined whether health behavior risk factors (smoking, drinking, physical activity, and body weight) for mortality vary by age and gender among 6,109 adults 45-74 years old in the National Health and Nutrition Examination Survey 1971-1975 (NHANES I) who were traced during the 1982-1984 NHANES I Follow-up Survey. RESULTS: For middle-aged men (45-54 years old) and for older men (65-74 years old), both smoking and nonrecreational physical activity were predictors of survival time. Additionally, for older men, drinking and low body mass index were associated with shorter survival time. Among women, there was less consistency of associations across age groups. As with men, nonrecreational physical activity and low body mass index were associated with shorter survival among older women. CONCLUSIONS: These findings suggest that health behaviors are associated with survival in older adults as well as in middle-aged adults, although the specific behavioral risk factors may vary by age and gender.

Adult↗

PubMed1994

Long-term physical functioning in persons with knee osteoarthritis from NHANES. I: Effects of comorbid medical conditions.

This study examined the effects of comorbid medical conditions (heart disease, pulmonary disease, hypertension and obesity) on the association of radiographic knee osteoarthritis (OA) with long-term difficulty in physical function. Data are from the National Health and Nutrition Examination Survey, 1971-1975 (NHANES I), a prospective epidemiologic cohort study, and the NHANES Epidemiologic Follow-up Study, 1982-1984 (NHEFS) and included 4059 persons who were 45-74 years old and participated in the detailed examination component of NHANES I. Knee OA was ascertained by anterior-posterior bilateral radiographs of the knee and self-report of knee pain, heart and pulmonary disease by self report of disease or symptoms, and hypertension and obesity by blood pressure and weight measurements. The presence of symptomatic knee OA at NHANES I was associated with reported difficulty at NHEFS 1982-84 in functions which used the lower extremity (ambulation and transfer). The presence of coexistent chronic conditions, particularly heart disease, pulmonary disease and obesity, increased the likelihood of subsequent disability. These findings suggest that knee OA is associated with long-term physical disability, and that the presence of coexistent chronic disease may increase the amount of long-term disability from knee OA.

Activities of Daily Living↗

PubMed1994

Mutation analysis of the C-terminal vacuolar targeting peptide of tobacco chitinase: low specificity of the sorting system, and gradual transition between intracellular retention and secretion into the extracellular space.

The C-terminal propeptide of tobacco (Nicotiana tabacum) chitinase A has been shown to be necessary and sufficient for targeting of chitinases to the plant vacuole. The sequence specificity of this vacuolar targeting peptide (VTP) has now been analysed using transient expression of chitinases in Nicotiana plumbaginifolia protoplasts. An extracellular cucumber chitinase, previously used as a secreted reporter protein in transgenic tobacco, was also secreted into the incubation medium by the transiently transformed protoplasts. Addition of six to seven amino acids at the C-terminus to generate the VTP of tobacco chitinase A were sufficient to cause retention of most of the cucumber chitinase within the protoplasts. The chitinase A itself, as well as a mutant lacking the N-terminal chitin-binding domain, were retained to 80% in the protoplasts when low concentrations of the plasmid were used in the transient expression system. At high concentrations of plasmid, causing high levels of transiently expressed chitinase, retention was reduced, indicating saturation of the sorting system. Deletion of the C-terminal methionine did not affect the intracellular location, but deletion of even a single internal amino acid of the VTP caused predominantly secretion of tobacco chitinase A. In contrast, exchanges of amino acids in the VTP as well as substitution of the VTP with random sequences had intermediary effects that covered the whole range from retention to secretion. The results suggest that the sorting system responsible for the diversion of secretory proteins to the vacuole has a low specificity for the sequence of C-terminal targeting peptides, and that sequence changes in the VTP allow a gradual transition from vacuolar retention to secretion.

Amino Acid Sequence↗