Ganglioside GT1b inhibits keratinocyte adhesion and migration on a fibronectin matrix

Highly sialylated gangliosides have been shown to alter cellular adhesion to a fibronectin matrix. The effect of these gangliosides on the adhesion, spreading, and migration of cultured keratinocytes on a fibronectin matrix has not been explored. Ganglioside GT1b significantly prevented attachment of keratinocytes to fibronectin and also detached previously adherent keratinocytes in a concentration-dependent manner without cell toxicity. GT1b did not affect adhesion of keratinocytes to wells coated with laminin, type I or type IV collagen, 804G extracellular matrix, or albumin. GT1b also inhibited keratinocyte migration on fibronectin in a concentration-dependent manner at concentrations as low as 5 nM GT1b, but had no effect on migration of keratinocytes plated on other matrices. GT1b binds to intact fibronectin and to the 120-kD RGDS-containing cell-binding fibronectin fragment, but not to the heparin- or gelatin-binding fragments of fibronectin. Although RGDS competes with GT1b in inhibiting adhesion, GT1b does not diminish binding of keratinocytes to a derivatized RGDS substratum, suggesting that the GT1b effect involves a non-RGDS site in the cell-binding region that modulates RGDS/alpha 5 beta 1 integrin receptor interaction. Through a specific effect on keratinocyte interaction with fibronectin, GT1b may participate in the regulation of cell adhesion and migration on a fibronectin substratum, which are important events during wound healing and the spreading of cutaneous neoplasia.     

The problems of present-day enterology

The European Union has a formal interest in public health under the Article 129 of the Maastricht Treaty. Hitherto, the main contribution of the European Union action in public health has been limited to research, health information and education concerning, in particular major diseases and drug dependence. Unfortunately the European architects did not clearly conceive a plan for the establishment of a common health policy despite the fact that the European health policies are fragmented and are often the indirect results of economic policies. Indeed, the domain of public health is essentially governed by the principle of national sovereignty, onto which the principle of subsidiarity has been grafted. Whereas Article 129 of the Maastricht Treaty applies especially to preventive health policies, the concomitant affirmation of the principle of subsidiarity in this field tends to suspend any establishment of a European health policy. In the same way, the lack of compulsory provisions relating to Community actions, expressed as recommendations, raises the question whether the European Union is willing to move to a European health policy.     

Avian adenovirus induces ion channels in model bilayer lipid membranes

The action of duck egg drop syndrome 1976 (EDS-76) adenovirus on model bilayer lipid membranes (BLM) has been investigated on planar egg phosphatidylcholine membranes and small unilamellar vesicles. It was found that the adenovirus formed channels in planar BLM in a pH-dependent manner. The addition of EDS-76 to planar BLM at pH 5 induced voltage-independent channel activity of about 60 pS conductivity after a lag phase. At pH 3, EDS-76 induced irregular spikes of current across the planar BLM which disappeared after several minutes. The adenovirus also was able to induce pH-dependent leakage of calcein-loaded liposomes. EDS-76 did not induce channel activity in planar BLM or liposome leakage at neutral pH.     

Scenario of chronic dermatophytosis: an Indian study

It is widely accepted that tumor invasion and metastasis are the primary causes for the lethal clinical outcome of cancers. In recent years, attention has been drawn to PCNA (Proliferating Cell Nuclear Antigen) to predict the prognosis of some cancers. In the present paper, we have studied anti-PCNA antibody PC10 in supraglottic cancer by means of immunohistochemistry using paraffin-embedded sections, to demonstrate its clinical significance in this type of malignancy. Twenty-two patients with supraglottic cancer, including T1 (5 cases), T2 (13 cases) and T4 (4 cases) with N- (14 cases) and N+ (8 cases), were investigated for the PCNA expression. The percentages of PCNA positive cells were divided into three groups: < 25%, 25-75%, > 75%, with the range from 10.6 to 95.2%. Results showed that PCNA was well correlated with lymph node metastasis, and appeared to have an inverse correlation with histopathological grades. In this small group, we did not find that PCNA was correlated with T stages and tumor size. However, compared with other T-stages and tumor sizes, the correlation between lymph node metastasis and PCNA seemed to have more clinical significance in T2-stage and in tumors larger than 2 cm. PCNA could be used as a marker in predicting the clinical outcome in supraglottic cancers. An analysis on a large scale is anticipated.     

Expression of pro form of prostate-specific antigen by mammalian cells and its conversion to mature, active form by human kallikrein 2

To study the expression, biosynthesis, and processing of prostate-specific antigen (PSA) in mammalian cells, recombinant PSA was expressed in Syrian hamster tumor cell line AV12-664 (AV12-PSA). Expression of PSA was monitored by the Tandem-MP PSA assay. PSA was secreted into the medium during the logarithmic phase of cell growth at >9 microg/ml and was stable. The PSA purified from spent medium of AV12-PSA cells did not exhibit any enzymatic activity and did not complex with the protease inhibitor, alpha-1-antichymotrypsin. These findings indicated that an inactive form of PSA was expressed by AV12-PSA cells. NH2-terminal sequencing confirmed the identity of the PSA purified from the spent medium of AV12-PSA cells to be pro-PSA. This demonstrates that PSA is expressed as pro-PSA by mammalian cells and suggests that pro-PSA may be present in biological fluids. Human kallikrein 2 (hK2), another member of the hK family, is also expressed predominantly in prostate epithelium. Although hK2 has been shown to exhibit trypsin-like activity, little is known about its natural substrates. Using purified proteins, we show that hK2 can convert pro-PSA to mature, enzymatically active PSA, thus establishing a physiological connection between hK2 and PSA. These findings imply that hK2 may be regulating PSA activity in vivo.     

Accumulation of human immunodeficiency virus-specific cytotoxic T lymphocytes away from the predominant site of virus replication during primary infection

Down-regulation of the initial burst of viremia during primary human immunodeficiency virus (HIV) infection is thought to be mediated predominantly by HIV-specific CD8+ cytotoxic T lymphocytes (CTL). This response is associated with major perturbations in the T cell receptor (TCR) repertoire. To investigate the failure of the cellular immune response to adequately control viral spread and replication and to prevent establishment of HIV infection, changes in the TCR repertoire and in the distribution of virus-specific CTL between blood and lymph node were analyzed in three patients with primary infection. By the combined use of clonotype-specific polymerase chain reaction and analysis of the frequency of in vivo activated HIV-specific CTL, it was shown that HIV-specific CTL clones preferentially accumulated in blood as opposed to lymph node. Accumulation of HIV-specific CTL in blood occurred prior to effective down-regulation of virus replication in both blood and lymph node. These findings should provide new insights into how HIV, and possibly other viruses, elude the immune response of the host during primary infection.