Heterologously expressed Staphylococcus aureus fibronectin-binding proteins are sufficient for invasion of host cells

Staphylococcus aureus invasion of mammalian cells, including epithelial, endothelial, and fibroblastic cells, critically depends on fibronectin bridging between S. aureus fibronectin-binding proteins (FnBPs) and the host fibronectin receptor integrin alpha(5)beta(1) (B. Sinha et al., Cell. Microbiol. 1:101-117, 1999). However, it is unknown whether this mechanism is sufficient for S. aureus invasion. To address this question, various S. aureus adhesins (FnBPA, FnBPB, and clumping factor [ClfA]) were expressed in Staphylococcus carnosus and Lactococcus lactis subsp. cremoris. Both noninvasive gram-positive microorganisms are genetically distinct from S. aureus, lack any known S. aureus surface protein, and do not bind fibronectin. Transformants of S. carnosus and L. lactis harboring plasmids coding for various S. aureus surface proteins (FnBPA, FnBPB, and ClfA) functionally expressed adhesins (as determined by bacterial clumping in plasma, specific latex agglutination, Western ligand blotting, and binding to immobilized and soluble fibronectin). FnBPA or FnBPB but not of ClfA conferred invasiveness to S. carnosus and L. lactis. Invasion of 293 cells by transformants was comparable to that of strongly invasive S. aureus strain Cowan 1. Binding of soluble and immobilized fibronectin paralleled invasiveness, demonstrating that the amount of accessible surface FnBPs is rate limiting. Thus, S. aureus FnBPs confer invasiveness to noninvasive, apathogenic gram-positive cocci. Furthermore, FnBP-coated polystyrene beads were internalized by 293 cells, demonstrating that FnBPs are sufficient for invasion of host cells without the need for (S. aureus-specific) coreceptors.     

Coronary artery lesions in Takayasu's arteritis--clinical and angiographic study

Two hundred and twenty five patients of Takayasu's arteritis were studied over 13 years. Male:Female ratio was 1:7. Mean age of the study population was 19 +/- 4 years. Of these 225 patients, 75 patients had symptoms and/or signs of cardiac involvement and these patients were subjected to coronary angiography. Significant coronary artery occlusion (i.e. more than 50% narrowing of luminal diameter) was present in 9 patients. Incidence of coronary artery lesions in Takayasu's arteritis is 12% in this study. The proximal segments of coronary arteries were involved while the distal segments were spared. Out of 34 patients with angina pectoris, only 3 patients had significant coronary arterial narrowing.     

Tetanus toxin fragment C expressed in live Salmonella vaccines enhances antibody responses to its fusion partner Schistosoma haematobium glutathione S-transferase

Tetanus toxoid has been used widely as an adjuvant. The atoxic fragment C from tetanus toxin (TetC) is potently immunogenic when expressed in Salmonella vaccine strains and has been used as a fusion partner for antigens (Ag). However, there has been no formal comparison of the immunomodulatory impact of TetC on its fusion partners. In this study, we have addressed this important issue. The protective 28-kDa glutathione S-transferase (GST) from Schistosoma haematobium (Sh28GST) was expressed either as a fusion to TetC or as the full-length Sh28GST alone in a nonvirulent aroA-attenuated strain of Salmonella enterica serovar Typhimurium. The Sh28GST proteins were soluble and stably expressed in Salmonella, as evaluated by Western blotting with TetC and/or Sh28GST antisera. Mice were immunized orally with a single dose of the live recombinant Salmonella. The constructs were stable in mice but, dramatically, only the strain expressing the TetC-Sh28GST fusion elicited significant antibody (Ab) responses directed against Sh28GST as determined by enzyme-linked immunosorbent assay. An analysis of the isotype profiles showed that these mice also produced anti-Sh28GST immunoglobulin A and GST-neutralizing assays revealed high levels of neutralizing Abs in sera. These are important correlates of protection in schistosomiasis. In addition, stimulation of spleen cells from immunized mice with Sh28GST Ag showed that both strains, expressing Sh28GST alone or the TetC-Sh28GST fusion, were able to stimulate the secretion of Th1-related cytokines (gamma interferon and interleukin 2) to comparable levels. Thus, TetC has modulated the immune responses generated against its fusion partner, Sh28GST, by markedly enhancing the Ab responses elicited. These results have important implications in the rational development of live vaccines.     

Immunocytochemical localization of cathepsin D in rat ventral prostate: evidence for castration-induced expression of cathepsin D in basal cells

Cathepsin D (EC3.4.23.5) is an aspartyl endopeptidase involved in lysosomal proteolysis. Its functional role is uncertain. This study was undertaken to determine the cellular and subcellular distribution of cathepsin D in the normal rat ventral prostate and its possible role in the castration-induced atrophy of the gland. Cathepsin D was localized immunohistochemically to perinuclear lysosomes in secretory cells, in capillary endothelial cells, and, occasionally, in stromal cells of the untreated animal. Castration resulted in an increased number of cathepsin D-positive cells in the stroma within 24 hr. By 48 hr after castration autophagolysosomes formed in secretory cells and apoptotic bodies appeared in the epithelium. Although apoptotic bodies generally contained immunoreactive cathepsin D, a subpopulation of larger apoptotic bodies, which commonly rested on the basement membrane and contained multiple inclusions, were more variable in cathepsin D expression. The induction of cathepsin D in dendritic cells basally oriented in the epithelium was noted at 4 days of castration. These cells had a phagocytic phenotype, were distributed periodically along the basement membrane, and were not found in ductal epithelia. Treatment with actinomycin D or hydrocortisone to reduce the rate of regression of the ventral prostate blocked the appearance of these cathepsin D-positive, basally oriented epithelial cells. Our data indicate that this cathepsin D-positive, phagocytic cell differentiates from a cell resident in the prostatic epithelium. We suggest that it differentiates from basal cells in the secretory tubuloalveolar portion of the gland and that it is involved in the destruction of regressed secretory cells.     

Expansion of CTG repeat in myotonin protein kinase gene on Alu(ins)-HinfI-I background in a myotonic dystrophy patient from India. Mutations in brief no. 210. Online

To determine the founder of Indian myotonic dystrophy mutation, we have studied the expansion of CTG repeats in myotonin protein kinase gene and two intragenic linked loci Alu(ins) / Alu(del) and G/T intron 9 HinfI polymorphism in ten unrelated DM patients from eastern India. Out of these ten patients, reconstruction of haplotype was possible for five patients unambiguously. In the other five cases, haplotype for the normal allele was assumed to be the most common haplotype found in normal individuals from Indian populations. Such analysis showed that in nine cases, the expansion of CTG repeats took place on Alu(ins)-HinfI-2 background indicating common founder with other DM mutation published. However, in one case we observed a different haplotype [Alu(ins)-HinfI-1] which could be a new mutation or due to admixture.     

Robinow syndrome

Robinow syndrome is a rare congenital abnormality. It is characterized by mesomelic brachymelia, hemivertebrae, dysmorphic facies, genital hypoplasia, micropenis, clinodactyly, camptodactly, hypoplastic nails and moderate short stature. We are documenting the case on the account of its rarity and additional features.     

NO LINKAGE OR ASSOCIATION OF TELOMERIC AND CENTROMERIC T-CELL RECEPTOR β-CHAIN MARKERS WITH SUSCEPTIBILITY TO TYPE 1 INSULIN-DEPENDENT DIABETES IN HLA-DR4 MULTIPLEX FAMILIES

The T-cell receptor β locus (TCRB) on chromosome 7q35 was studied as a candidate region for genetic susceptibility to type 1 insulin-dependent diabetes (IDDM). A highly polymorphic microsatellite marker mapping to the TCRBV6.7 gene and a TCRB C-region RFLP were used to genotype the members of a total of 21 multiplex IDDM families from two different geographical areas. There was no evidence to support linkage to either of these markers with IDDM, and conventional two-point analysis excluded linkage to the telomeric end of the TCRB complex, in the region of the highly informative TCRBV6.7 marker. There was significant linkage of IDDM to the class II HLA-D locus with significant lod scores >3.0 obtained for the HLA-DRB1 and HLA-DQB1 genes. Affected sib-pair (ASP) and transmission disequilibrium (TDT) association tests confirmed these findings.     

RecurrentStreptococcus pneumoniae endocarditis

A case of recurrent endocarditis due toStreptococcus pneumoniae, a rare cause of endocarditis, is reported. The first episode of infection resulted in valvular damage, necessitating replacement of the aortic and mitral valves, and the second episode was treated successfully with antibiotics alone. Recurrence occurred even though the organism was fully susceptible to the antibiotics used and the patient showed no evidence of immune deficiency.