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Biomedical subjects

J R Davis

Publications and source records attributed to J R Davis.

At least 19 recordsLinked to original sources
PubMed1992

Analysis of a giant marker chromosome in a well-differentiated liposarcoma using cytogenetics and fluorescence in situ hybridization.

Well-differentiated liposarcomas (LPS) are cytogenetically very complex, characterized by giant marker chromosomes, ring chromosomes, and telomeric associations. We report a case of well-differentiated LPS in which the only cytogenetic anomaly was an additional giant marker. In an attempt to identify the origin of this marker, centromeric probes (chosen on the basis of the morphology of the marker) to chromosomes 1,2,3,4,6,7,8,9,10,11,12,16,17, and X and a shared satellite probe for chromosomes 1,5, and 19, were used with fluorescence in situ hybridization (FISH). This was successful at eliminating certain chromosomes as candidates for centromeric trisomy but could not identify the origin of the marker. This case is unusual in that it does not conform to the typical cytogenetic pattern for well-differentiated LPS and is the first known example with an apparently normal diploid karyotype with only one additional change.

Aged↗
PubMed1992

Early activation of the proto-oncogene c-fgr during Epstein-Barr virus immortalization.

In an attempt to clarify the chronological relationships between Epstein-Barr virus (EBV) infection, B cell immortalization and c-fgr activation, we evaluated for the presence of EBV-determined nuclear antigen (EBNA), cellular DNA synthesis and expression of c-fgr-specific RNA following infection of human peripheral blood lymphocytes with B95-8 EBV. High expression of c-fgr was observed prior to EBNA detection and cellular DNA synthesis in EBV-infected cells. These results suggest that activation of c-fgr is an essential event during the early phase of EBV immortalization.

Antigens, Viral↗
PubMed1992

Family pesticide use in the home, garden, orchard, and yard.

This study examined family use of pesticides in the home, garden, orchard, and yard. Data were collected from 238 families in Missouri during telephone interviews from June 1989 to March 1990. Nearly all families (97.8%) used pesticides at least one time per year and two thirds used pesticides more than five times per year. More than 80% used pesticides during pregnancy and 70% used pesticides during the first 6 months of a child's life. The most common setting for family pesticide use was in the home, where 80% of families used pesticides at least once per year. This was followed by herbicide use to control yard weeds (57% of families) and insecticide use to control fleas and ticks on pets (50% of families). A substantial number of families also used pesticides in the garden or orchard (33%). Flea collars were the most popular pest control product (50% of families). Carbaryl or Sevin was also popular, with 28.2% of families reporting use. No-pest-strips (dichlorvos) and Kwell shampoo (lindane) were used by almost 10% of participating families. Examination of study data revealed that families limited exposure to pesticides for the mother during pregnancy and for children during the first 6 months of life. Families failed to recognize and reduce pervasive exposures associated with no-pest-strips and flea collars.

Animals↗
PubMed1992

Plasmodium falciparum: in vitro characterization and human infectivity of a cloned line.

The culture-adapted NF54 isolate of Plasmodium falciparum was subjected in vitro to three sequential limiting dilution titrations and the resulting clone was given the designation CVD1. DNA sequence analysis of the gene encoding the circumsporozoite (CS) protein revealed differences between CVD1 and the published NF54 CS gene. CVD1 had 1191 bp, 397 amino acids, and 42 repeat units while NF54 had 1218 bp, 405 amino acids, and 44 repeat units. The CVD1 clone was more sensitive to chloroquine than was the parental line, in vitro. Anopheles stephensi mosquitoes were infected equally by the cloned and uncloned parasites. Volunteers were readily infected by NF54 and CVD1 following infectious mosquito bites. The availability of a well-characterized, chloroquine-sensitive clone which safety infects humans should facilitate performance of experimental challenge studies to assess vaccine efficacy.

Amino Acid Sequence↗
PubMed1992

Ring chromosome in a dermatofibrosarcoma protuberans.

We report the cytogenetic findings in a case of dermatofibrosarcoma protuberans in a 40-year-old male. Chromosome analysis revealed one clone consisting of +7, +11, +13, +14, +15, and a ring chromosome. This is consistent with two previously reported cases, each of which also had a single ring chromosome.

Adult↗
PubMed1992

Duration of larval development of Simulium yahense (Diptera: Simuliidae) under natural conditions.

The duration of Simulium yahense Vajime & Dunbar larval development on a dam spillway in Harbel, Liberia, was observed to make accurate decisions regarding the frequency of larvicide treatments against this onchocerciasis vector. Larval development required a minimum of 10-12 d from eclosion to first pupation. Initial larvicidal treatment for S. yahense control would require a treatment cycle of 7 d. Once suppression of adult and larval populations is achieved, a 9-12-9-12 day treatment cycle could be adopted.

Animals↗
PubMed1992

Comparison of norepinephrine and serotonin vasoconstriction of the rat isolated testicular subcapsular artery at physiological and elevated transmural pressures.

This laboratory has previously described an in vitro preparation showing that the isolated testicular subcapsular artery of the adult rat has a novel triphasic transmural pressure-diameter myogenic response curve consisting of vasodilatation from 20 to 40 mm Hg, vasoconstriction from 40 to 100 mm Hg, and vasodilatation from 100 to 180 mm Hg, suggesting that the myogenic response of this artery between 40 and 100 mm Hg may have an important role in the autoregulation of the testicular blood supply. In the present studies, a 10-mm length of the adult rat isolated testicular subcapsular artery was cannulated and pressurized by an adjustable-height reservoir. External and internal arterial diameters were measured by a digital filar micrometer eyepiece. Dose-response curves for norepinephrine and serotonin were generated in a double-bath artery chamber at transmural pressures of 70 and 140 mm Hg, using half of the same artery for each pressure. Norepinephrine (3 x 10(-8) to 1 x 10(-5) M) produced a dose-dependent vasoconstriction at 70 mm Hg, with the highest dose causing a 31.4% decrease in lumen cross-sectional area (p < 0.05). Serotonin (3 x 10(-8) to 1 x 10(-6) M) produced a stronger dose-dependent vasoconstriction at 70 mm Hg, with the highest dose causing a 72.7% decrease in lumen cross-sectional area (p < 0.05). In marked contrast, the same concentration of norepinephrine and serotonin were found to have no statistically significant effect on the lumen cross-sectional area of the isolated testicular subcapsular artery at a transmural pressure of 140 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
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

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↗