Tumorigenic potential of extracellular matrix metalloproteinase inducer.

Extracellular matrix metalloproteinase inducer (EMMPRIN), a glycoprotein present on the cancer cell plasma membrane, enhances fibroblast synthesis of matrix metalloproteinases (MMPs). The demonstration that peritumoral fibroblasts synthesize most of the MMPs in human tumors rather than the cancer cells themselves has ignited interest in the role of EMMPRIN in tumor dissemination. In this report we have demonstrated a role for EMMPRIN in cancer progression. Human MDA-MB-436 breast cancer cells, which are tumorigenic but slow growing in vivo, were transfected with EMMPRIN cDNA and injected orthotopically into mammary tissue of female NCr nu/nu mice. Green fluorescent protein was used to visualize metastases. In three experiments, breast cancer cell clones transfected with EMMPRIN cDNA were considerably more tumorigenic and invasive than plasmid-transfected cancer cells. Increased gelatinase A and gelatinase B expression (demonstrated by in situ hybridization and gelatin substrate zymography) was demonstrated in EMMPRIN-enhanced tumors. In contrast to de novo breast cancers in humans, human tumors transplanted into mice elicited minimal stromal or inflammatory cell reactions. Based on these experimental studies and our previous demonstration that EMMPRIN is prominently displayed in human cancer tissue, we propose that EMMPRIN plays an important role in cancer progression by increasing synthesis of MMPs.

Barriers to adherence to highly active antiretroviral therapy as expressed by people living with HIV/AIDS.

The primary objective of this study was to gain a clearer understanding of the barriers to adherence to highly active antiretroviral therapy (HAART) faced by people living with HIV/AIDS (PLWHIV/AIDS) on Long Island, New York. Focus group, a qualitative research method, was used to study these barriers. The study was conducted in 1998 on Long Island, NY, at five institutions that provide services to 1700 PLWHIV/AIDS. Five focus groups were conducted with 6 to 13 PLWHIV/AIDS in each group, a total of 39 subjects. PLWHIV/AIDS identified eight common barriers to adherence to HAART. In descending order, the barriers include: (1) frequency and severity of side effects, (2) conflicts with daily routines, (3) dietary requirements, (4) frequency of taking medications, (5) number and dosage of medications, (6) psychosocial factors (i.e., stress, feeling good, and bad news), (7) pharmacy refills, and (8) physiological needs (i.e., sleep, hunger, or thirst). Many factors play a role in the success or failure of HAART, including preexisting drug resistance, drug-drug interactions, and the ability of PLWHIV/AIDS to adhere to a rigid and frequently changing medication regimen. The information gleaned from focus groups is limited in that it may not be generalized to a larger population with any known reliability. However, clinicians sensitive to barriers to adherence to HAART, including those identified by PLWHIV/AIDS in this study, may play a more proactive role in supporting adherence to the medication regimen, increasing the durability of effective viral suppression, decreasing morbidity and mortality, and decreasing the selection and transmission of resistant strains of HIV.

Tuberculosis.

Dental health care providers must play an active role in preventing the transmission of tuberculosis. The information presented here should allow them to appropriately identify and refer patients who may be infectious, identify oral lesions which may be due to tuberculosis, and develop and implement an infection control plan to prevent transmission in the dental setting.

Activation of human umbilical vein endothelial cell progelatinase A by phorbol myristate acetate: a protein kinase C-dependent mechanism involving a membrane-type matrix metalloproteinase.

Matrix metalloproteinases play an important role in tumor invasion, angiogenesis and inflammatory tissue destruction. The 72-kd gelatinase A is the most widely distributed. Along with the 92-kd gelatinase B, it plays an important role in basement membrane turnover. Gelatinase A is secreted as progelatinase A and, when activated, can cause extracellular matrix destruction. The physiologic mechanism of this activation is not well understood. Based on the importance of endothelial cells in inflammation and cancer, we sought in this study to systematically study the PMA-induced activation of endothelial cell progelatinase A. Using HUVEC, we demonstrated that PMA-induced activation of progelatinase A in these vascular endothelial cells (a) was protein kinase C-dependent as it was blocked by H-7; (b) occurred through cell-mediated events as PMA was unable to activate progelatinase A in a cell-free system and that low dose tissue inhibitor of metalloproteinases-2, but not tissue inhibitor of metalloproteinases-1, totally inhibited PMA-induced activation; (c) was accompanied by an increase in the membrane-type matrix metalloproteinase (MT-MMP). We also found that the combination of PMA and the cytokine tumor necrosis factor-alpha increased HUVEC secretion and activation of gelatinase B. In conclusion, our data show that PMA activation of vascular endothelial cell progelatinase A is a cell membrane event that is at least partially mediated through a PKC-dependent mechanism and is accompanied by an increase synthesis of MT-MMP. These data suggest a role for MT-MMP in the activation of progelatinase A in vascular endothelial cells.

Staphylococcus aureus proteins that bind to human endothelial cells.

The adherence of Staphylococcus aureus to human endothelial cells is saturable in both dose- and time-dependent assays. Staphylococcal surface components which bound to endothelial cells in vitro were identified by using biotin-labeled, solubilized staphylococcal proteins. Four trypsin-sensitive components with molecular sizes of 30, 55 to 57, 70, and 85 kDa were recognized. These proteins did not label with the glycan detection system. When staphylococci were harvested during the exponential phase of growth, staphylococcal adherence to endothelial cells was significantly increased and increased expression of the S. aureus binding proteins was observed. Preincubation of endothelial cells with protein A did not reduce S. aureus adherence in an in vitro infection assay. Four S. aureus surface components whose expression is growth phase dependent adhere to human endothelial cells in vitro.

A human endothelial cell membrane protein that binds Staphylococcus aureus in vitro.

We have investigated S. aureus adherence to human endothelial cells utilizing an in vitro model. Staphylococcus binding to confluent endothelial cell monolayers was saturable in both dose and time response studies suggesting that the binding interaction was specific. We have developed a technique, based on the pH dependent affinity of iminobiotin for streptavidin, for the isolation of an endothelial cell membrane component that binds S. aureus, in vitro. A 50-kD membrane component was isolated and purified using this approach. This component was trypsin sensitive, periodate insensitive, and did not label with [3H]glucosamine. [35S]Methionine and [125I]iodine labeling confirmed that the protein was synthesized by and expressed on the endothelial cell surface. Functional binding studies demonstrated that staphylococci, but not endothelial cells, bound to the protein when immobilized on microtiter wells. Preincubation of staphylococci with the purified protein significantly (P less than 0.001) reduced staphylococcal binding to cultured endothelial cells. The capacity of S. aureus to colonize and invade endovascular surfaces may in part be a consequence of staphylococcal interaction with this endothelial cell membrane protein.

Bloodstain characterization in the EAP, Hp, Hb, AK and Glo I typing systems using minigels and the PhastSystem.

Application of minigels and the PhastSystem to obtain phenotyping results from bloodstains in the EAP, Hp, AK, and Glo I typing systems was investigated. Nonequilibrium isoelectric focusing with 4-6.5 PhastGel produced readily interpretable phenotypes in the EAP typing system. Both 4-6.5 and 5-8 PhastGel produced AK typing system phenotypes using nonequilibrium isoelectric focusing conditions. The 8-25% PAG PhastGel developed by two staining techniques allowed discrimination of phenotypes for the Hp typing system. Phenotypes from the Glo I typing system were also obtained with this gel type. Variant haemoglobins could be detected on pH 5-8 PhastGel using isoelectric focusing conditions. Much potential for standardized, rapid phenotyping of bloodstains was found to exist utilizing the PhastSystem.

Pericapillary permeability of the ciliary processes: role of molecular charge.

The pericapillary permeability of the ciliary processes to intravenously injected native (anionic) ferritin, neutral ferritin, and two cationic ferritin derivatives was studied in normal rats by electron microscopy. Anionic and neutral ferritin were largely confined to the circulatory compartment. Those particles that entered the pericapillary region of the ciliary processes were randomly scattered within the basal lamina. In contrast, cationic ferritin left the circulatory compartment and accumulated in the pericapillary region in association with the endothelium, the endothelial fenestrations, and the subendothelial basal lamina. The most cationic of the tracers used exhibited the greatest penetration and accumulation. The results indicate that the localization of tracer within the pericapillary region of the ciliary processes is directly related to the tracer's isoelectric point. The findings suggest that this region of the ciliary processes contains fixed anionic groups that influence its permeability.

Rat CNS in experimental chronic serum sickness: integrity of the zonulae occludentes of the choroid plexus epithelium and brain endothelium in experimental chronic serum sickness.

The present study is an extensive systematic immunofluorescence and labelled electron microscopic investigation of chronic rat serum sickness brains. It is specifically directed at discerning effects of chronic serum sickness upon the zonulae occludentes of both the choroid plexus epithelium and the intra-cerebral endothelium. Although the choroid plexus is a known site of complex entrapment in systemic immune complex disorders, comprehensive immune studies of the CNS parenchymal vasculature have not yet been reported in either experimental or spontaneous immune complex disease. We examined by direct immunofluorescence techniques over 70 blocks of experimental chronic serum sickness brains taken from 16 animals with severe glomerular disease and found them to be uniformly negative for the presence of immune deposits. No horseradish peroxidase was seen beyond the restricting zonulae occludentes of either the choroid plexus or the cerebral endothelium in tissue from three serious affected animals. These structural barriers retained their integrity despite the extensive circulation and deposition of complexes and complement induced in the experimental model and the associated release of vasoactive substances.

Rat ciliary process in chronic serum sickness: light, immunofluorescence, and electron microscopy.

The ciliary processes of 26 male Wistar rats that survived a prolonged period of immunization with bovine serum albumin (BSA) and a similar number of age- and sex-matched controls were studied by immunofluorescence and electron microscopy. The findings in the ciliary process were compared with those of the renal glomeruli. Granular subepithelial deposits of rat IgG, C3, and BSA were demonstrated by direct immunofluorescence in the ciliary process and renal glomeruli of 38% and 85% of experimental animals, respectively. Electron microscopy of the positive immunofluorescent cases disclosed electron-dense single masses and clusters in the basement membrane regions below the epithelial layers. Experimental chronic serum sickness appears to offer an excellent approach toward understanding the pathogenesis of uveal involvement in human serum sickness and in the "collagen-vascular" diseases.