Search PubMed⌕ Search

Biomedical subjects

J R Davis

Publications and source records attributed to J R Davis.

At least 127 records · Page 7Linked to original sources
PubMed1992

Gender and histologic type variations in smoking-related risk of lung cancer.

We conducted a registry-based case-control study to examine the relation between smoking and lung cancer by gender and histologic type. Our analyses were based on 14,596 cases and 36,438 age-matched controls. Relative risk associated with ever-smoking, and level of smoking was consistently higher in females than males for all lung cancers combined (ever-smoking odds ratios: 12.7 for females and 9.1 for males) and for each histologic type except adenocarcinoma. Female-male differences in relative risk were larger in younger age groups. The largest estimates of the attributable fraction due to smoking were observed for small cell carcinoma (97% in females and 91% in males); conversely, the smallest value was noted for adenocarcinoma (86% in females). Although our study was unable to measure absolute risk, our findings, other recent studies, and contemporary female smoking patterns raise concerns that female smokers may assume a proportionally greater burden of lung cancer morbidity and mortality in the future.

Adenocarcinoma↗
PubMed1992

Automated systems for identification of microorganisms.

Automated instruments for the identification of microorganisms were introduced into clinical microbiology laboratories in the 1970s. During the past two decades, the capabilities and performance characteristics of automated identification systems have steadily progressed and improved. This article explores the development of the various automated identification systems available in the United States and reviews their performance for identification of microorganisms. Observations regarding deficiencies and suggested improvements for these systems are provided.

Bacteria↗
PubMed1992

Serum cytokine profiles in experimental human malaria. Relationship to protection and disease course after challenge.

Serum cytokine profiles were evaluated in immunized and nonimmunized human volunteers after challenge with infectious Plasmodium falciparum sporozoites. Three volunteers had been immunized with x-irradiated sporozoites and were fully protected from infection. Four nonimmune volunteers all developed symptomatic infection at which time they were treated. Sera from all volunteers were collected at approximately 20 time points during the 28-d challenge period; levels of IL-1 alpha, IL-1 beta, IL-2, IFN-gamma, tumor necrosis factor-alpha, IL-4, IL-6, granulocyte macrophage-colony-stimulating factor, and soluble CD4, CD8, and IL-2 receptor (sCD4, sCD8, and sIL-2R, respectively) were determined by ELISA. C-reactive protein (CRP) was assayed by radial immunodiffusion. Parasitemic subjects developed increases in CRP and IFN-gamma, with less marked increases in sIL-2R and sCD8; the other cytokines tested did not change. CRP increases were abrupt and occurred at the onset of fever (day 14 after challenge). IFN-gamma increases were also abrupt, preceding those of fever and CRP by one day. Increases in sIL-2R and sCD8 were more gradual. Increases in fever, CRP, IFN-gamma, and sCD8 were concordant in each volunteer. Early IL-6 increases were noted in the protected vaccinees. Thus, after challenge with virulent P. falciparum, unique systemic cytokine profiles were detectable both in immunized, nonparasitemic volunteers and in unvaccinated, parasitemic subjects. The contrasting cytokine profiles in the two groups may relate to mechanisms of protection and immunopathology in experimental human malaria.

Animals↗
PubMed1992

Transforming growth factor-beta 1 production in porcine thyroid follicular cells: regulation by intrathyroidal organic iodine.

The present studies have demonstrated the production of transforming growth factor-beta 1 (TGF-beta 1) by porcine thyroid follicular cells (TFCs) maintained in vitro as subconfluent monolayers, and have confirmed a stimulatory effect of iodide on thyroidal TGF-beta 1 mRNA and peptide release. RNA extracted from TFCs maintained in the absence of iodide contained a 2.5 kb transcript which hybridized specifically with a cDNA probe for human TGF-beta 1, and which showed an approximate doubling in intensity in cells exposed to 10 mumol NaI/1. In the presence of the anti-thyroid thionamide drug methimazole (MMI; 1 mmol/l), the action of iodide on TGF-beta 1 mRNA was attenuated, although MMI alone had no effect on the control level of TGF-beta 1 mRNA. The TGF-beta 1 peptide content of TFC-conditioned media (TFC-CM) was assessed using the fetal mink lung cell line Mv1Lu, in which activated TGF-beta 1 specifically suppresses trichloroacetic acid-precipitable [methyl-3H]thymidine incorporation. Newly conditioned TFC-CM stimulated [methyl-3H]thymidine incorporation into Mv1Lu cells, but after heat treatment to inactivate growth stimulators and activate the latent TGF-beta 1 component this medium inhibited [methyl-3H]thymidine incorporation. This inhibitory effect was prevented by immunoadsorption of TFC-CM with a TGF-beta 1-neutralizing antiserum, confirming the specificity of the inhibitory response. The inhibitory activity of TFC-CM was increased when the TFCs were preincubated with 10 mumol NaI/1, and lost when TFCs were exposed to MMI. In conclusion, TFCs produce TGF-beta 1 mRNA and TGF-beta 1 peptide, which are both increased by iodide treatment in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Demographic and socioeconomic differences in beliefs about the health effects of smoking.

To assess sociodemographic differences in beliefs about the health effects of cigarette smoking and passive smoke exposure, we recently surveyed 2092 adults in St. Louis and Kansas City, Mo. The percentages of respondents who knew that smoking causes lung cancer, emphysema, and heart disease were 76.7, 74.1, and 67.2, respectively. After multivariate adjustment, knowledge about smoking's health effects was generally lower among women, older respondents, those of lower education level, and current smokers. Blacks were generally less likely to appreciate the health effects of active smoking, but were more likely to acknowledge the health effects of passive smoking.

Adolescent↗
PubMed1992

Ingestion of Plasmodium falciparum sporozoites during transmission by anopheline mosquitoes.

We investigated the process of sporozoite transmission during blood feeding for Anopheles gambiae and An. stephensi experimentally infected with Plasmodium falciparum. When infective mosquitoes were fed 22-25 days postinfection on an anesthetized rat, sporozoites were detected in the midgut of 96.5% of 57 An. gambiae (geometric mean [GM] = 32.5, range 3-374) and in 96.2% of 26 An. stephensi (GM = 19.5, range 1-345). There were no significant differences between species either in salivary gland sporozoite loads or in the number of ingested sporozoites. There was a significant linear relationship between sporozoite loads and the numbers of ingested sporozoites for both An. gambiae (r = 0.38) and An. stephensi (r = 0.69). Subsequently, An. gambiae were tested for sporozoite transmission by allowing them to feed individually on a suspended capillary tube containing 10 microliters of blood. A total of 83.3% of 18 infective mosquitoes transmitted a GM of 5.9 (range 1-36) sporozoites. The same mosquitoes contained a GM of 23.4 (range 2-165) ingested sporozoites. The number of ingested sporozoites was related to sporozoite loads (r = 0.42) but not to the number of sporozoites ejected into capillary tubes. Ingested sporozoites remained in the midgut up to 10 hr after feeding. The comparable numbers of sporozoites ingested by infective mosquitoes in both experiments indicates that the actual number of sporozoites transmitted to the vertebrate host during blood feeding is significantly reduced by the blood ingestion process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Comparison of treatment strategies for Space Motion Sickness.

Treatment strategies for Space Motion Sickness were compared using the results of postflight oral debriefings. Standardized questionnaires were administered to all crewmembers immediately following Space Shuttle flights by NASA flight surgeons. Cases of Space Motion Sickness were graded as mild, moderate or severe based on published criteria, and medication effectiveness was judged based on subjective reports of symptom relief. Since October 1989, medication effectiveness is reported inflight through Private Medical Conferences with the crew. A symptom matrix was analyzed for 19 crewmembers treated with an oral combination of scopolamine and dextroamphetamine (scopdex) and 15 crewmembers treated with promethazine delivered by intramuscular (IM) or suppository routes. Scopdex has been given preflight as prophaxis for Space Motion Sickness but analysis showed delayed symptom presentation in 9 crewmembers or failed to prevent symptoms in 7. Only three crewmembers who took scopdex had no symptoms inflight. Fourteen out of 15 crewmembers treated with IM promethazine and 6 of 8 treated with promethazine suppositories after symptom development had immediate (within 12 h) symptom relief and required no additional medication. There were no cases of delayed symptom presentation in the crewmembers treated with promethazine. This response is in contrast to untreated crewmembers who typically have slow symptom resolution over 72-96 h. We conclude that promethazine is an effective treatment of Space Motion Sickness symptoms inflight. NASA policy currently recommends treating crewmembers with Space Motion Sickness after symptom development, and no longer recommends prophylaxis with scopdex due to delayed symptom development and apparent variable absorption of oral medications during early flight days.

Aerospace Medicine↗
PubMed1992

Epstein-Barr virus-associated lymphoproliferative disorders.

Herein we have provided a panorama of the clinical, histopathologic, and molecular biologic mechanisms of EBV-induced LPD particularly in immunosuppressed individuals. A listing of EBV-related diseases is shown in Table 4. We have stressed the frequent need to use multiple diagnostic methods for detecting EBV genome, particularly in immunodeficient patients who may fail to mount antibody responses to EBV. Given that we now recognize some of the immunocompromised patient populations at high risk for EBV-induced LPD, and have developed techniques for detecting EBV genome and early LPD, we may eventually prevent the occurrence of some of these life-threatening diseases. For example, we have learned to recognize and distinguish hepatic allograft rejection from EBV-induced LPD in hepatic biopsies (154). A periportal and sinusoidal infiltrate of small and large lymphoid cells, immunoblasts, and plasma cells, alert us to stain frozen liver sections for EBNA. Finding EBV guides the clinicians to reducing immunosuppression which then allows the restoration of immunosurveillance against the EBV-infected B cells. Whether an EBV vaccine can be successful in immunosuppressed individuals remains to be seen. As for other vaccines, many logistical problems prevail, such as the early occurrence of EBV infection during infancy in regions where BL is endemic. Surely, with the menacing threat that approximately 10% of patients with AIDS will develop NHL, new anti-viral therapy against EBV and the causative agent of AIDS and HIV, will be developed. The pathologist and virologist play essential roles in the recognition of EBV infection by performing clinical laboratory determinations. The characteristic histopathologic features of EBV-induced LPD are now recognized and when confirmed with molecular hybridization and immunofluorescent techniques will provide a solid diagnostic approach and, thus, a foundation for developing a sound therapeutic strategy.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Sporozoite transmission by Anopheles freeborni and Anopheles gambiae experimentally infected with Plasmodium falciparum.

A micro-membrane feeding technique was used to evaluate sporozoite transmission for Anopheles freeborni and An. gambiae experimentally infected with Plasmodium falciparum. From cohorts of infected mosquitoes with equivalent sporozoite loads, 75.9% of 29 An. freeborni transmitted a geometric mean (GM) of 4.9 sporozoites and 80% of 30 An. gambiae transmitted a GM of 11.3 sporozoites. Ingested sporozoites, in the blood meal immediately after feeding, were detected in 86.2% of 29 An. freeborni (GM = 9.0) and in 70% of 30 An. gambiae (GM = 44.1). Overall, sporozoites were transmitted and/or ingested by 90% of both species. Most infective mosquitoes transmitted < 1% of the total sporozoites in the salivary glands, and only up to 30% of the variation in transmission, ingestion, or total sporozoite output was related to sporozoite loads. The demonstration that An. gambiae transmitted more than twice as many sporozoites as An. freeborni is the first indication that vector species of anopheline mosquitoes differ in their innate potential for sporozoite transmission.

Animals↗
PubMed1992

Hemagglutination and graft-versus-host disease in the severe combined immunodeficiency mouse lymphoproliferative disease model.

In the course of evaluating the severe combined immunodeficiency mouse-human peripheral blood lymphocyte (SCID-PBL) model of lymphoproliferative disease, we noted hemagglutination occurring in peripheral blood smears of mice with serum human immunoglobulin levels greater than 1.0 mg/ml. The hemagglutinating process was mediated by human anti-mouse red cell antibodies of the IgM class, peaked at five to seven weeks post-transfer of 5 to 7 x 10(7) human PBL and was generally self limiting. However, death resulted in some mice when serum immunoglobulin levels were greater than 3.0 mg/ml. The most severely affected mice had hemagglutination induced congestion of liver, lungs and spleen. Several mice also had lesions consistent with graft-versus-host disease (GVHD) including focal hepatic necrosis and destruction of mouse splenic hematopoietic elements. The lesions associated with hemagglutination and GVHD in SCID-PBL mice are distinct from those associated with EBV-induced lymphoproliferation. Recognition of these pathologic processes are required for a thorough understanding of the SCID-PBL model.

Animals↗
PubMed1991

Cigarette smoking and risk of adult leukemia.

A case-control study investigated the relation between cigarette smoking and histologic subtypes of adult leukemia in Missouri in 1984-1990. Among males, elevated risks associated with ever smoking were observed for acute nonlymphocytic leukemia (odds ratio (OR) = 1.5; 95% confidence interval (CI) 1.1-2.0) and acute myelocytic leukemia (OR = 1.5; 95% CI 1.1-2.1). Females also showed an increased risk of acute nonlymphocytic leukemia associated with ever smoking (OR = 1.4; 95% CI 1.0-1.9), with an increasing trend in risk by level of smoking (p less than 0.01). Attributable risk estimates of the proportion of acute nonlymphocytic leukemia caused by smoking were 33 percent in males and 29 percent in females. Elevations in risk were not apparent for chronic forms of leukemia. The findings support the hypothesis that some types of leukemia may be etiologically related to cigarette smoking.

Adult↗
PubMed1991

Intratumoral cytogenetic heterogeneity in a benign neoplasm.

Cytogenetic findings are reported in a 64-year-old man who had a history of rapid growth of a mass in the left groin area. The histopathologic diagnosis of the tumor was consistent with that of a lipoma with atypia. Cytogenetic analysis was done on an incisional biopsy specimen. The initial biopsy specimen revealed, in addition to normal cells, three different clones: 46,XY,t(12;21)(q13;q21), 46,XY, t(2;12)(q11.2'1.2), t(19;20)(q13.1'3), and 47.XY,+ r. The subsequently excised specimen showed a normal male karyotype (46,XY) and a predominant clone with the karyotype, 47,XY,t(2;12)(q11.2'1.2),t(3;11)(p24'5), + r. One cell with 47,XY, + r was present. In addition, polyploid cells with large markers, rings, and a high frequency of telomeric associations were also observed.

Chromosome Aberrations↗
PubMed1991

SCID mouse model of Epstein-Barr virus-induced lymphomagenesis of immunodeficient humans.

Immunodeficient humans are at very high risk of developing Epstein-Barr virus (EBV)-induced lymphomagenesis. Severe combined immunodeficient mice (SCID) have been shown to develop lymphoproliferative disease (LPD) following transfer of peripheral blood leukocytes (PBL) with latent EBV. To study mechanisms of lymphomagenesis, we compared results of engraftment of PBL from normal donors and immunodeficient donors with X-linked lymphoproliferative disease (XLP). Graft-versus-host disease (GVHD) developed in 6 of 10 SCID mice 4 to 8 weeks following transfer of PBL from normal donors. In contrast, none of 9 mice engrafted with PBL from XLP patients with T-cell defects showed GVHD. LPD developed in mice regardless of the immune competence of the donors. The expression of EBV-encoded proteins, results of immunophenotyping, and karyotyping of the LPD lesions revealed lethal oligoclonal LPD owing to transfer of latent EBV in B cells in mice engrafted with PBL from seropositive donors. Polyclonal LDP developed in mice engrafted with PBL from seronegative patients which were infected with B95-8 virus 6 weeks after transfer of the cells. This model is useful for investigating mechanisms of EBV-induced LDP in immunodeficient patients.

Animals↗
PubMed1991

Detection of primary Epstein-Barr virus infection in a patient with X-linked lymphoproliferative disease receiving immunoglobulin prophylaxis.

Serologic diagnosis for Epstein-Barr virus (EBV) infection is problematic when patients receive exogenous immunoglobulin. We recently diagnosed primary EBV infection by detecting EBV-determined nuclear antigen (EBNA) and EBV-DNA in peripheral blood mononuclear cells (PBMC) using immunofluorescence, in situ hybridization and polymerase chain reaction (PCR) techniques in a patient with X-linked lymphoproliferative disease (XLP) who received prophylactic immunoglobulins for EBV infection. These combined techniques may be helpful for early and accurate diagnosis of EBV infection in highly vulnerable patients.

Adult↗
PubMed1991

Cytogenetic and flow cytometric analysis of a clear cell chondrosarcoma.

Cytogenetic analysis of a rare tumor, a clear cell chondrosarcoma of the spine, showed unusual karyotypic findings. The tumor had a predominant clone with a near-haploid chromosome complement of 30 chromosomes with loss of one homologue of each chromosome pair except chromosomes 5, 7, 12, and 19-22. A second clone with 58-60 chromosomes appeared to have originated by a doubling of the near-haploid clone. No structural changes were present. Comparison with other solid tumors and leukemias with near-haploid chromosome complements showed an interesting difference in the chromosomes which were preferentially disomic or monosomic in the two groups. Quantitative DNA analysis also showed aneuploid clones of cells corresponding to the near-haploid and hyperdiploid chromosome counts obtained cytogenetically.

Adult↗
PubMed1991

Multihormonal regulation of the human prolactin gene expression from 5000 bp of its upstream sequence.

We have cloned DNA sequences extending up to 6000 bp upstream from the first exon of the human prolactin (hPRL) gene. 5000 bp of these upstream sequences were fused to a CAT reporter gene and shown to provide tissue-specific transient expression in rat pituitary GH3 cells. Multihormonal response was found in this transient expression assay, leading to significant 2- to 5-fold induction by addition of 8-chlorophenylthio-cyclic AMP, thyrotropin-releasing hormone, epidermal growth factor, basic fibroblast growth factor, phorbol myristate acetate, a calcium channel agonist (Bay K-8644) and triiodothyronine. A 3-fold inhibition was observed in the presence of the glucocorticoid agonist dexamethasone. The sequence of the hPRL promoter was determined up to coordinate -3470. Computer similarity search between the rat and human sequences showed two highly conserved regions corresponding to the proximal and distal tissue specific enhancers described in both PRL promoters.

Animals↗
PubMed1991

Morphonuclear relationship between prostatic intraepithelial neoplasia and cancers as assessed by digital cell image analysis.

Using digital cell image analysis performed on Feulgen-stained nuclei, the nuclear characteristics of prostatic neoplasia, ranging from benign (benign prostatic hyperplasia [BPH]), through dysplastic (prostatic intraepithelial neoplasia [PIN] 1-3), to carcinoma were studied. Four histopathologic groups were studied: group IA (18 samples) contained BPH, PIN 1, and PIN 2 lesions that were from 9 prostate samples free of cancer. Group IB (23 samples) was identical to group IA, contained also BPH, PIN 1, and PIN 2 lesions, but lesions that were from 7 prostate samples where malignant foci were detected elsewhere. Group II (11 samples) were PIN 3 specimens. Group III (24 samples) were carcinomas. Features of neoplastic nuclei were quantified objectively through morphometric (nuclear size), densitometric (nuclear DNA content), and textural (chromatin organization and heterogeneity) parameters. Cell kinetic parameter, i.e., cell proliferation index, was assessed from the densitometric measurement. The proliferation index was significantly higher in PIN 3 and cancers as compared to BPH, PIN 1, and PIN 2 tissues. Morphonuclear characteristics were also dramatically distinct among the four groups. Indeed, the nuclear size and the hyperchromatism of severe prostatic dysplasia were similar to those of carcinomas, these two lesion types showing mean parameter values that were higher as compared to BPH, PIN 1, and PIN 2 lesions. Finally, benign tissues related to mild or moderate dysplasia taken in histologic material in which cancer was present already share the morphonuclear characteristics of severe dysplasia, although they are nonproliferating.

Cell Nucleus↗