Biomedical subjects

J S Slater

Publications and source records attributed to J S Slater.

At least 19 recordsLinked to original sources

PubMed2001

Products of US22 genes M140 and M141 confer efficient replication of murine cytomegalovirus in macrophages and spleen.

Efficient replication of murine cytomegalovirus (MCMV) in macrophages is a prerequisite for optimal growth and spread of the virus in its natural host. Simultaneous deletion of US22 gene family members M139, M140, and M141 results in impaired replication of MCMV in macrophages and mice. In this study, we characterized the proteins derived from these three genes and examined the impact of individual gene deletions on viral pathogenesis. The M139, M140, and M141 gene products were identified as early proteins that localize to both the nucleus and cytoplasm in infected cells. Gene M139 encodes two proteins, of 72 and 61 kDa, while M140 and M141 each encode a single protein of 56 (pM140) and 52 (pM141) kDa, respectively. No role for the M139 proteins in MCMV replication in macrophages or mice was determined in these studies. In contrast, deletion of either M140 or M141 resulted in impaired MCMV replication in macrophages and spleen tissue. Replication of the M140 deletion mutant was significantly more impaired than that of the virus lacking M141. Further analyses revealed that the absence of the pM140 adversely affected pM141 levels by rendering the latter protein unstable. Since the replication defect due to deletion of M140 was more profound than could be explained by the reduced half-life of pM141, pM140 must exert an additional, independent function in mediating efficient replication of MCMV in macrophages and spleen tissue. These data indicate that the US22 genes M140 and M141 function both cooperatively and independently to regulate MCMV replication in a cell type-specific manner and, thus, to influence viral pathogenesis.

3T3 Cells↗

PubMed1999

Medical records as an alternative to self-report for measuring mammography utilization.

A pilot study assessed whether medical records were a viable alternative to self-report for measuring mammography use in a population-based sample. Of 98 women contacted by telephone, 62 (63.3%) ultimately provided written consent to obtain their mammogram reports. Although all physicians complied with requests for records, an average of three physician contacts per woman were required and 87 percent of mammogram reports were located; therefore, records were available for only 56 percent of women contacted initially. This, coupled with the effort associated with obtaining the records, does not support the use of medical records as an alternative to self-report to measure mammography utilization in the general population.

Female↗

PubMed1999

Replication of murine cytomegalovirus in differentiated macrophages as a determinant of viral pathogenesis.

Blood monocytes or tissue macrophages play a pivotal role in the pathogenesis of murine cytomegalovirus (MCMV) infection, providing functions beneficial to both the virus and the host. In vitro and in vivo studies have indicated that differentiated macrophages support MCMV replication, are target cells for MCMV infection within tissues, and harbor latent MCMV DNA. However, this cell type presumably initiates early, antiviral immune responses as well. In addressing this paradoxical role of macrophages, we provide evidence that the proficiency of MCMV replication in macrophages positively correlates with virulence in vivo. An MCMV mutant from which the open reading frames M139, M140, and M141 had been deleted (RV10) was defective in its ability to replicate in macrophages in vitro and was highly attenuated for growth in vivo. However, depletion of splenic macrophages significantly enhanced, rather than deterred, replication of both wild-type (WT) virus and RV10 in the spleen. The ability of RV10 to replicate in intact or macrophage-depleted spleens was independent of cytokine production, as this mutant virus was a poor inducer of cytokines compared to WT virus in both intact organs and macrophage-depleted organs. Macrophages were, however, a major contributor to the production of tumor necrosis factor alpha and gamma interferon in response to WT virus infection. Thus, the data indicate that tissue macrophages serve a net protective role and may function as "filters" in protecting other highly permissive cell types from MCMV infection. The magnitude of virus replication in tissue macrophages may dictate the amount of virus accessible to the other cells. Concomitantly, infection of this cell type initiates the production of antiviral immune responses to guarantee efficient clearance of acute MCMV infection.

3T3 Cells↗

PubMed1999

Improving cancer incidence estimates for American Indians in Minnesota.

OBJECTIVES: The purpose of this study was to estimate cancer incidence for American Indians in Minnesota. METHODS: Indian Health Service enrollment data were linked to the Minnesota tumor registry to identify cancers among American Indians in Minnesota. Incidence rates for the 5 most common cancers in this population, estimated after the linkage, were compared with rates estimated before the linkage and with rates for the total population of Minnesota. RESULTS: The linkage identified 302 cancer cases not previously identified as occurring among American Indians in Minnesota. Postlinkage estimates suggested that incidence rates for prostate and colorectal cancer are similar to those for the total population of Minnesota, but that rates of lung and cervical cancer are significantly higher. Breast cancer rates are slightly lower than those for the total population of Minnesota but more than twice as high as previous estimates for American Indians. CONCLUSIONS: The postlinkage estimates suggest different priorities for cancer education, prevention, and control than might be assumed from either prelinkage estimates or previously published data, and underscore the importance of using accurate and specific data for setting these priorities.

Female↗

PubMed1998

Accuracy of self-report of mammography and Pap smear in a low-income urban population.

BACKGROUND: Cancer screening history can often be obtained only by self-report, particularly for disadvantaged populations. We examined the accuracy of self-report of mammography and Pap smear for an urban, low-income population. METHODS: Women attending non-primary care clinics (mostly surgery and orthopedics) at a large public teaching hospital in Minneapolis between July 1992 and May 1993 were queried about their screening history (n = 477). The women were interviewed by a trained peer-recruiter and asked whether they had ever heard of a Pap smear or mammogram, whether they had ever had one, where it was done, and when the last one was. We verified self-report by checking medical records where the test was performed. RESULTS: The positive and negative predictive value of recall of mammography in the previous year was 72.4% and 90.6%, respectively. The figures for Pap smear recall were somewhat lower, 65.5% and 85.9%, respectively. We found a record of a mammogram in 88% of women able to recall the year. Of these, slightly over two-thirds recalled their mammogram in the same year as their record indicated. Inaccurate recalls were more commonly of the "telescoping" type, i.e., tests were recalled as having occurred more recently than was the case. Recall was substantially better for recent tests. Results for Pap smear recalls were broadly similar. CONCLUSIONS: The accuracy of self-report of mammography and Pap smear is relatively poor for medical practice but is acceptable in population surveys with appropriate correction for overreporting.

Adult↗

PubMed1998

Increasing breast and cervical cancer screening in low-income women.

OBJECTIVE: To determine if women would have higher breast and cervical cancer screening rates if lay health advisers recommended screening and offered a convenient screening opportunity. DESIGN: Controlled trial. SETTING: Urban county teaching hospital. PARTICIPANTS: Women aged 40 years and over attending appointments in several non-primary-care outpatient clinics. INTERVENTIONS: Lay health advisers assessed the participants' breast and cervical cancer screening status and offered women in the intervention group who were due for screening an appointment with a female nurse practitioner. MEASUREMENTS AND MAIN RESULTS: Screening rates at baseline and at follow-up 1 year after the intervention were determined. At follow-up, the mammography rate was 69% in the intervention group versus 63% in the usual care group (p = .009), and the Pap smear rate was 70% in the intervention group versus 63% in the usual care group (p = .02). In women who were due for screening at baseline, the mammography rate was 60% in the intervention group versus 50% in the usual care group (p = .006), and the Pap smear rate was 63% in the intervention group versus 50% in the usual care group (p = .002). The intervention was effective across age and insurance payer strata, and was particularly effective in Native American women. CONCLUSIONS: Breast and cervical cancer screening rates were improved in women attending non-primary-care outpatient clinics by using lay health advisers and a nurse practitioner to perform screening. The effect was strongest in women in greatest need of screening.

Adult↗

PubMed1998

Measuring mammography compliance: lessons learned from a survival analysis of screening behavior.

Data from a telephone survey of women participating in a federally funded screening program were used to demonstrate the sensitivity of mammography compliance estimates to varying definitions of the time interval within which women are considered compliant with screening guidelines and what constitutes a true screening (as opposed to diagnostic) mammogram. The survival analysis approach used reveals patterns concealed by other approaches to measuring mammography behavior and provides a means for quantifying the impact of various definitional choices on compliance estimates. The results suggest that, although variations in defining and excluding potential diagnostic mammograms lead to differences in compliance measures no greater than 6%, differences as small as 1 month in the screening interval definition used can produce differences in compliance estimates as large as 27%. These results call into question the comparability of estimates across studies and suggest that standard measures would greatly facilitate future efforts in understanding how to promote compliance with mammography screening guidelines.

Adult↗

PubMed1997

Down-regulation of MHC class I synthesis by murine cytomegalovirus occurs in immortalized but not primary fibroblasts.

Murine cytomegalovirus downregulates expression of MHC class I molecules required for recognition of virus-specific CD8+ CTL, effector cells which mediate clearance of virus from the host. We previously identified two mechanisms of MHC class I downregulation in MCMV-infected immortalized fibroblasts: a defect in transport of the class I molecules from the endoplasmic reticulum to the cell surface, and a significant inhibition in class I heavy chain synthesis. We now report that these two mechanisms are independently regulated at early times post MCMV infection. The defect in MHC class I transport, evident at 4 hr postinfection, precedes the defect in synthesis at 6-8 hr postinfection. Levels of MHC class I heavy chain mRNA decline between 4-12 hr postinfection. Levels of mRNA for some cellular genes also declined at approximately the same rate in MCMV-infected but not mock-infected cells. The defect in MHC class I synthesis and transport was evident in several fibroblast cell lines immortalized by a variety of agents. However, only the defect in transport of MHC class I heavy chain was seen in primary fibroblast cells. In primary cells, synthesis of heavy chain molecules was unaffected by MCMV infection. Thus, MCMV infection alters expression of host cell proteins at multiple levels in a cell-specific manner, perhaps dependent upon the state of differentiation or transcriptional activity of the cell.

Animals↗

PubMed1997

Why do patients of female physicians have higher rates of breast and cervical cancer screening?

OBJECTIVE: Women are more likely to receive breast and cervical cancer screening if they see female physicians. We studied whether this is due to differences between male and female physicians, or to differences in their patients. SETTING: Large midwestern, independent practice association style of health plan. DESIGN: We surveyed male and female primary care physicians matched for age and specialty and a stratified random sample of three of each physician's women patients. Physicians reported on their practice setting, their attitudes and practices regarding prevention, and their comfort and skill with various examinations. Patients reported on their sociodemographic characteristics, their attitudes and practices regarding prevention, and their preferences for physician gender. Claims data were used to calculate mammography and Pap smear screening rates for the physicians. PARTICIPANTS: We studied 154 female and 190 male internists and family physicians and 794 of their patients. MEASUREMENTS AND MAIN RESULTS: We compared the responses of male and female physicians and their patients and used multivariable analysis to identify the patient and physician factors that accounted for the differences in screening rates between male and female physicians. Female physicians were more likely to ask new patients about components of prevention, to believe in the effectiveness of mammography, to feel more personal responsibility for ensuring that their patients received screening, and to report more comfort in performing Pap smears and breast examinations. Patients of female physicians were more educated and less likely to be married, but did not differ in other sociodemographic characteristics. They had similar attitudes and practices regarding prevention, except that patients of male physicians were more likely to smoke. Significantly more patients of female physicians preferred a female for some component of care. In multivariable analyses, practice organization, patient preference for a female physician, and prevention orientation of female physicians accounted for up to 40% of screening rate differences between female and male physicians for Pap smears, and 33% for mammography. CONCLUSIONS: Differences in beliefs of male and female physicians and patient preference for a female provider contribute independently to the higher rate of breast and cervical cancer screening by female physicians.

Adult↗

PubMed1997

Questionable data and preconceptions: reconsidering the value of mammography for American Indian Women.

Although the benefits of mammography are well established, many remain skeptical of the value of mammography for American Indian women. This skepticism stems in part from a belief that breast cancer is too rare an event among American Indians to warrant widespread screening. The validity of this assumption for Northern Plains Indians is challenged by a discussion of the limitations of available data on breast cancer in American Indian populations (including lack of generalizability, underestimation, and an overreliance on relative rather than absolute measures of cancer incidence) and by findings from the Minnesota Breast and Cervical Cancer Control Program, a federally funded program providing free breast and cervical cancer screening to American Indian and other women in Minnesota. In light of this information, the authors recommend that the low priority of mammography for American Indian women be reconsidered.

Breast Neoplasms↗

PubMed1995

Multiple independent loci within the human cytomegalovirus unique short region down-regulate expression of major histocompatibility complex class I heavy chains.

Reduction of major histocompatibility complex class I cell surface expression occurs in adenovirus-, herpes simplex virus-, human cytomegalovirus (HCMV)-, and murine cytomegalovirus-infected cell systems. Recently, it was demonstrated that the down-regulation mediated by HCMV infection is posttranslational, as a result of increased turnover of class I heavy chains in the endoplasmic reticulum (M. F. C. Beersma, M. J. E. Bijlmakers, and H. L. Ploegh, J. Immunol. 151:4455-4464, 1993; Y. Yamashita, K. Shimokata, S. Saga, S. Mizuno, T. Tsurumi, and Y. Nishiyama, J. Virol. 68:7933-7943, 1994. To identify HCMV genes involved in class I regulation, we screened our bank of HCMV deletion mutants for this phenotype. A mutant with a 9-kb deletion in the S component of the HCMV genome (including open reading frames IRS1 to US9 and US11) failed to down-regulate class I heavy chains. By examining the effects of smaller deletions within this portion of the HCMV genome, a 7-kb region containing at least nine open reading frames was shown to contain the genes required for reduction in heavy-chain expression. Furthermore, it was determined that at least two independent loci within the 7-kb region were able to cause class I heavy-chain down-regulation. One of these, US11, encodes a 32-kDa glycoprotein which causes down-regulation of class I heavy chains in the absence of other viral gene products. Hence, a specific function associated with a phenotype of the HCMV replicative cycle has been mapped to a dispensable gene region. These loci may be important for evasion of the host's immune response and viral persistence.

Astrocytoma↗

PubMed1994

Down-regulation of major histocompatibility complex class I synthesis by murine cytomegalovirus early gene expression.

Murine cytomegalovirus (MCMV) infection of C57BL/6 (H-2b) mice prevents priming of antigen-specific helper and cytotoxic T lymphocytes (CTL) (J. S. Slater, W. S. Futch, V. J. Cavanaugh, and A. E. Campbell, Virology 185:132-139, 1991). In vitro, MCMV infection alters presentation of antigens to antigen-specific, MHC class I-restricted CTL (A. E. Campbell, J. S. Slater, V. J. Cavanaugh, and R. M. Stenberg, J. Virol. 66:3011-3017, 1992). This is accompanied by a significant decrease in surface expression of H-2Kb and H-2Db. We therefore examined the effects of MCMV infection on the intracellular expression of H-2Kb and H-2Db by immunoprecipitation with conformation-independent antibodies. MCMV early-gene products severely repressed synthesis of H-2Kb and H-2Db. This down-regulation was not restored by gamma interferon treatment. The MCMV-induced suppression of MHC class I protein synthesis resulted in a retarded rate of accumulation of these molecules within the cell. In addition, MCMV infection prevented maturation of class I heavy chains to the fully glycosylated forms and inhibited transport of H-2Db from the endoplasmic reticulum-cis Golgi. Virus infection had no effect on the rate of degradation of the class I molecules. These results demonstrate that MCMV early-gene products down-regulate synthesis and posttranslational events in MHC class I expression, thereby limiting the number of antigen-presenting molecules within infected cells. This limitation defines a potential mechanism for regulation of MHC class I-restricted antigen presentation by MCMV.

Animals↗

PubMed1994

Preventing cervical cancer.

Primary physicians should be sure their women patients of all ages are being screened for cervical cancer. Underinsured women with low incomes may be referred to the Minnesota Breast and Cervical Cancer Control Program for free exams.

Adult↗

PubMed1993

Predictors of failure to attend scheduled mammography appointments at a public teaching hospital.

OBJECTIVE: To identify patient, institutional, and physician characteristics that predict failure to attend scheduled mammography appointments. DESIGN: Retrospective chart review. SETTING: Medicine clinic at an urban public teaching hospital. PATIENTS: All 907 women aged 40 years and more scheduled for mammography from March 1990 to June 1991. MEASUREMENTS AND MAIN RESULTS: The main outcome measure was whether a woman kept her scheduled mammography appointment. Potential predictor variables included patient age, race, marital status, and insurance status; waiting interval to obtain a mammography appointment; and physician gender, level of training, country of training, and native language. The rate of failed mammography appointments was 23%. Univariate analysis showed that appointment failure was associated with age (p = 0.03), with the lowest failure rates (19%) among women aged 60 years and more. Appointment keeping varied significantly by race (p = 0.01), largely because of the higher failure rate among Native American women (36%). Insured women had a failure rate of 22% vs 33% for uninsured women (p = 0.01). The rate of failed appointments varied significantly by waiting interval (p = 0.05), with a peak failure rate of 27% for appointments scheduled 14-27 days in advance. None of the physician variables was associated with appointment failure. Multivariate analysis confirmed these results. CONCLUSIONS: Interventions to improve completion of breast cancer screening should include additional efforts targeted at groups with high rates of appointment failure, such as women under the age of 60, the uninsured, and Native Americans. Long waiting intervals to obtain mammography appointments may decrease compliance.

Adult↗

PubMed1992

An early event in murine cytomegalovirus replication inhibits presentation of cellular antigens to cytotoxic T lymphocytes.

Cytomegalovirus (CMV) infection of simian virus 40 (SV40)-immune mice inhibits priming of SV40-specific helper and cytotoxic T lymphocytes (CTL) in vivo (A. E. Campbell, J. S. Slater, and W. S. Futch, Virology 173:268-275, 1989; J. S. Slater, W. S. Futch, V. J. Cavanaugh and A. E. Campbell, Virology 185:132-139, 1991). We now demonstrate that murine CMV (MCMV) infection of SV40-transformed macrophages and fibroblasts prevents presentation of SV40 T antigen to SV40-specific CTL. MCMV-infected macrophages failed to stimulate SV40-immune CTL precursors in vitro. In addition, MCMV-infected, SV40-transformed macrophage and fibroblast target cells lost their susceptibility to lysis by major histocompatibility complex class I-restricted, SV40-specific CTL clones. MCMV infection did not alter the synthesis of SV40 T antigen in the target cells. MCMV early gene expression was required for inhibition of SV40 T-antigen presentation; immediate-early gene expression was insufficient for this effect. Early viral gene expression also resulted in significant reduction of H-2K and H-2D molecules on the surface of MCMV-infected fibroblasts. However, this reduction occurred independently from suppression of antigen presentation to CTL. The same target cells which were resistant to lysis by SV40 CTL were susceptible to lysis by MCMV-specific CTL. MCMV early gene products therefore interfere with the processing and/or presentation of SV40 T-antigen determinants to CTL independent of alterations in the major histocompatibility complex.

Animals↗

PubMed1991

Murine cytomegalovirus independently inhibits priming of helper and cytotoxic T lymphocytes.

Murine cytomegalovirus (MCMV) inhibits antigen-specific cytotoxic T lymphocyte (CTL) priming in vivo (Campbell et al., 1989). To address the mechanism of this immune suppression, two possibilities were considered: (1) MCMV directly interferes with in vivo priming of CTL precursors (CTLp), or (2) MCMV suppresses T helper cell functions necessary for CTL priming. We therefore quantitated T helper cell function in MCMV-infected, SV40-immune mice and assessed dependency of SV40-specific CTLp priming on T helper cell activity. MCMV infection of H-2b mice significantly suppressed the frequency of IL-2 producing T helper cells generated in SV40-immune mice. This suppression was not due to alterations in the number or percentage of CD4 lymphocytes. The helper cell deficiency correlated with suppressed SV40-specific CTL activity. However, CTLp priming in vivo was found to be independent of CD4 T helper cells and IL-2. Therefore, the suppressive effects of MCMV on helper and cytotoxic T cell functions are independent, implying that MCMV directly inhibits an event in lymphocyte priming common to both helper and cytotoxic T cells.

Animals↗

PubMed1990

Enhancement of interleukin-1 activity by murine cytomegalovirus infection of a macrophage cell line.

The effect of murine cytomegalovirus (MCMV) infection on interleukin 1 (IL-1) secretion was assessed using the macrophage cell lines P388D1 and J774A.1. The former proved to be nonpermissive for MCMV in that infectious virus and viral immediate early protein (pp89) were not expressed in these cells. MCMV infection of the P388D1 cells had no effect on release of biologically active IL-1. In contrast, J774A.1 cells, which were semipermissive for virus replication and pp89 expression, secreted enhanced levels of IL-1 activity following infection. The enhancement was evident when infection either preceded or followed lipopolysaccharide stimulation of the macrophages. The relative proportion of IL-1 alpha and beta secreted from MCMV-infected cells was similar to noninfected controls. In addition, the bioactivity of intracellular IL-1 alpha escaping membranes of fixed cells was unaffected by virus infection. From these findings, we conclude that limited MCMV expression in the J774A.1 macrophage cell line enhances secretion of IL-1 alpha and beta bioactivity.

Animals↗

PubMed1989

Murine cytomegalovirus-induced suppression of antigen-specific cytotoxic T lymphocyte maturation.

Antigen-specific cytotoxic T lymphocyte (CTL) maturation was inhibited in mice acutely infected with murine cytomegalovirus (MCMV). When immunization with Simian virus 40 (SV40) either preceded or followed infection with MCMV by 1 day, the frequency of SV40-specific CTL precursors among lymph node cells (LNC) was significantly reduced compared to noninfected mice. Replication of the herpesvirus in LNC could not be detected; however, MCMV rendered noninfectious by heat treatment was not suppressive to CTL development. Lymph node cells from nonimmunized, MCMV-infected mice contained a cell(s) present in low frequency which suppressed in vitro maturation of SV40 CTL in immune lymph nodes from mice not infected with MCMV. These suppressor cells did not affect the antigen- and interleukin-2-dependent growth nor cytotoxic activity of a mature, SV40-specific CTL clone. These results indicate that MCMV interferes with immunoregulatory functions required for development of antigen-specific CTL precursors to mature effector CTL. The immunosuppression is mediated at least in part by the MCMV-induced suppressor cell(s).

Animals↗