Human immunodeficiency virus type 1 enters brain microvascular endothelia by macropinocytosis dependent on lipid rafts and the mitogen-activated protein kinase signaling pathway.

Brain microvascular endothelial cells (BMVECs) present an incomplete barrier to human immunodeficiency virus type 1 (HIV-1) neuroinvasion. In order to clarify the mechanisms of HIV-1 invasion, we have examined HIV-1 uptake and transcellular penetration in an in vitro BMVEC model. No evidence of productive infection was observed by luciferase, PCR, and reverse transcriptase assays.

HIV-1 penetrates coronary artery endothelial cells by transcytosis.

Background: The pathogenesis of HIV-1-related cardiomyopathy is poorly understood, but HIV-1 has been detected in cardiomyocytes. Whether HIV-1 penetrates into the myocardium by infection of coronary artery endothelial cells (CAEC) or using transcellular or paracellular routes across CAEC has not been resolved.

Materials And Methods: A model of the CAEC barrier was constructed with primary CAEC (derived from human coronary vessels).

Induction of heme oxygenase-1 expression in macrophages by diesel exhaust particle chemicals and quinones via the antioxidant-responsive element.

Diesel exhaust particles (DEP) contain organic chemicals that contribute to the adverse health effects of inhaled particulate matter. Because DEP induce oxidative stress in the lung and in macrophages, effective antioxidant defenses are required. One type of defense is through the expression of the antioxidant enzyme, heme oxygenase I (HO-1).

CXC and CC chemokine receptors on coronary and brain endothelia.

Background: Chemokine receptors on leukocytes play a key role in inflammation and HIV-1 infection. Chemokine receptors on endothelia may serve an important role in HIV-1 tissue invasion and angiogenesis.

Materials And Methods: The expression of chemokine receptors in human brain microvascular endothelial cells (BMVEC) and coronary artery endothelial cells (CAEC) in vitro and cryostat sections of the heart tissue was determined by light and confocal microscopy and flow cytometry with monoclonal antibodies.

Latex antigens: identification and use in clinical and experimental studies, including crossreactivity with food and pollen allergens.

Learning Objectives: The purpose of this review is to introduce the reader to the range of latex allergens that have been identified by polypeptide sequencing. This knowledge is important for the assessment of clinical latex hypersensitivity, including crossreactivity with food and aeroallergens.

Data Sources: Medline search and relevant publications and reviews from the English medical literature since 1989.

Role of HPV in tumorigenesis of oral keratinocytes.

HPV-immortalized human oral keratinocytes can convert to tumorigenic cells by chemical carcinogens while normal human keratinocytes cannot. The different responses of these cells to chemical carcinogens may be due to their different genomic stability. Since the genomic stability of cells is closely associated with cell cycle control, we correlated cell cycle progression with the cellular levels or activities of key G(1) phase cell cycle regulatory proteins, p21(WAF/CIP1), cyclins (A, D1 and E), cdks (cdk2 and cdk4), gadd45 and PCNA proteins in normal and HPV-immortalized oral keratinocytes before and after treatment with a genotoxic agent, actinomycin D.

Combined oral carcinogenicity of HPV-16 and benzo(a)pyrene: an in vitro multistep carcinogenesis model.

We previously immortalized normal human oral keratinocytes by transfection with recombinant HPV-16 DNA and subsequently exposed the cells to benzo(a)pyrene for 7 days. The exposure to benzo(a)pyrene modified the immortalized cells: the modified cells (HOK-16B-BaP) proliferated in an ordinary culture medium containing physiological calcium level (1.5 mM), but demonstrated only enhanced proliferation capacity without tumor formation in nude mice and failed to show in vitro anchorage-independency.

Effect of actinomycin-d on the cell-cycle progression and the expression of p53, waf1/cip1, gadd45, and mdm-2 genes in human oral keratinocytes - implication of human papillomavirus infection.

Exposure of human oral keratinocytes immortalized by transfection with 'high risk' HPV DNA to chemical carcinogens converts the cells to malignant phenotype, but it does not transform normal cells. To investigate the underlying mechanism for different chemical carcinogen susceptibility of normal and the HPV-immortalized oral keratinocytes to genotoxic agent, we studied the progression of cell cycle and the expression of p53, WAF1/CIP1, gadd45 and mdm-2 genes in normal and in the HPV-immortalized oral keratinocytes after exposing cells to actinomycin D. Normal oral keratinocytes demonstrated transient G(1) arrest after the exposure, but the HPV-immortalized cells did not.

Abortive replication of influenza virus A/WSN/33 in HeLa229 cells: defective viral entry and budding processes.

Since influenza A virus replication is defective in HeLa229 cells but productive in Madin-Darby canine kidney (MDCK) cells, we have investigated the steps in the infectious cycle of A/WSN/33 virus defective in HeLa229 cells. We find that both the entry and exit processes of the infectious cycle were defective in HeLa229 cells. During entry, viral adsorption was apparently normal in HeLa229 cells but a subsequent step(s) involving one or more processes namely the fusion/uncoating and nuclear transport of viral ribonucleoprotein was inefficient and slow compared to those in MDCK cells.

Inactivation of the p53 gene by either mutation or HPV infection is extremely frequent in human oral squamous cell carcinoma cell lines.

The state of p53 tumour suppressor and the frequency of high-risk human papillomavirus (HPV) infections were studied in nine human oral cancer cell lines. Three cancer cell lines (SCC-4, Tu-177 and FaDu) had similar amounts of p53 transcripts to normal cells, but contained significantly higher levels of p53 protein than the normal control cells. Sequencing highly conserved open reading frames of the p53 gene of these cancer cells showed point mutations in the SCC-4 and Tu-177 cell lines, a base transition from CCC to TCC occurred at codon 151; and in the line FaDu, a mutation of CGG to CTG occurred at codon 248.

Effect of UV-irradiation on cell cycle, viability and the expression of p53, gadd153 and gadd45 genes in normal and HPV-immortalized human oral keratinocytes.

We previously demonstrated neoplastic conversion of HPV-immortalized human oral keratinocytes by exposing cells to chemical carcinogens, but failed to transform normal human oral keratinocytes with same chemical carcinogens in vitro. Though the reason for different responses of normal and HPV-immortalized oral keratinocytes to chemical carcinogens remains speculative, the difference may be due to the capacity of normal cells and incapacity of HPV-immortalized cells for repairing damaged DNA induced by carcinogens. Since (1) the repair of damaged DNA takes place in G1/G2 phases of cell cycle, (2) wild type p53 plays major role in the induction of transient G1 and/or G2 arrests, and (3) the expression of gadd45 and gadd153 is also associated with the cell cycle arrest and DNA damage, we investigated transient cell cycle arrest and the expression of p53, gadd45 and gadd153 in normal human oral keratinocytes, HPV-immortalized oral keratinocytes, and an oral cancer cell line expressing mutant p53 after exposing cells to UV light.

Recombinant RNA polymerase: inducible overexpression, purification and assembly of Escherichia coli rpo gene products.

The genes, rpoA, rpoB and rpoC of Escherichia coli, which encode the RNA polymerase alpha-, beta- and beta'-subunits, respectively, have been individually placed on expression plasmids under the control of the bacteriophage T7 promoter. Induction of the T7 RNA polymerase gene in host cells harboring each of the three plasmids resulted in the extensive overproduction of the three polypeptides. The overproduced subunits were purified and assembled into a functional enzyme, whose specific activity and dependence on the sigma-factor were indistinguishable from native RNA polymerase purified by conventional methods.