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J Jose

Publications and source records attributed to J Jose.

At least 37 records · Page 2Linked to original sources
PubMed2000

Human T-cell response to meningococcal immunoglobulin A1 protease associated alpha-proteins.

A unique feature of the immunoglobulin A1 (IgA1) protease from pathogenic Neisseriae, i.e. N. meningitidis and N. gonorrhoeae, is its co-secretion with an amphipathic a-protein. Polymerase chain reaction (PCR) analysis of the respective iga(alpha). gene region in 48 meningococcal strains revealed that this protein domain is conserved throughout all isolates in four different principal variants. Despite strain-dependent size and sequence variations, sequence analysis showed common structural characteristics. More than 80% of the amino acid sequence of all a-proteins is dependent on the five amino acids Q, E, A, K and R, resulting in a pI> 10. The sequences are highly conserved at the N-terminus and the C-terminus and contain long amphipathic alpha-helical stretches. These stretches have a strong probability of forming coiled coil conformations and comprise short repetitive sequence modules with pronounced similarities to T-cell epitopes. We therefore analyzed the T-cell response of 20 volunteer blood donors to four peptides, representing such predicted epitopes, and a recombinant meningococcal alpha-protein. Sixteen donors reacted against at least one peptide after culture of peripheral blood mononuclear cells in interleukin (IL)-2-rich medium, while two individuals showed a positive reaction only against an IgA1 protease-derived control peptide. From one donor, we established and maintained T-cell clones specific for purified alpha-protein. Characterization of the T-cell clones revealed a CD3- and a CD4-positive phenotype and the secretion of IL-2 and interferon-gamma (IFN-gamma),

Amino Acid Sequence↗
PubMed1999

Trilateral retinoblastoma with an RB1 deletion inherited from a carrier mother: a case report.

A presentation of intracranial tumor in bilateral and unilateral retinoblastoma with or without family history is termed as trilateral retinoblastoma (TRB). It always occurs either as a pineal tumor or supra/parasellar tumor, which differ in presentation and prognosis. We report here the first case of TRB with transmission of retinoblastoma gene (RB1) deletion from an unaffected mother (a carrier), presenting as concurrent intracranial neoplasm with bilateral retinoblastoma. The presence of RB1 mutation in both child and mother could be responsible for development of intracranial neoplasm which occurred simultaneously with bilateral RB in our patient. Our patient, who had a suprasellar mass, received radiation and intrathecal chemotherapy, and died 6 months after diagnosis. The occurrence of intracranial tumor in an asymptomatic stage can be avoided by routine computed tomography (CT) and magnetic resonance imaging (MRI) scan, and improved survival can be achieved by aggressive multimodality therapy.

Adult↗
PubMed1999

Characterization of the essential transport function of the AIDA-I autotransporter and evidence supporting structural predictions.

The current model for autodisplay suggests a mechanism that allows a passenger protein to be translocated across the outer membrane by coordinate action of a C-terminal beta-barrel and its preceding linking region. The passenger protein, linker, and beta-barrel are together termed the autotransporter, while the linker and beta-barrel are here referred to as the translocation unit (TU). We characterized the minimal TU necessary for autodisplay with the adhesin-involved-in-diffuse-adherence (AIDA-I) autotransporter. The assumed beta-barrel structure at the C terminus of the AIDA-I autotransporter was studied by constructing a set of seven AIDA-I-cholera toxin B subunit fusion proteins containing various portions of AIDA-I. Surface exposure of the cholera toxin B moiety was assessed by dot blot experiments and trypsin accessibility of the chimeric proteins expressed in Escherichia coli JK321 or UT5600. Export of cholera toxin B strictly depended on a complete predicted beta-barrel region. The absolute necessity for export of a linking region and its influence on expression as an integral part of the TU was also demonstrated. The different electrophoretic mobilities of native and denatured chimeras indicated that the proposed beta-barrel resides within the C-terminal 312 amino acids of AIDA-I. Together these data provide evidence for the predicted beta-barrel structure and support our formerly proposed model of membrane topology of the AIDA-I autotransporter.

Adhesins, Escherichia coli↗
PubMed1997

The Neisseria gonorrhoeae gene aniA encodes an inducible nitrite reductase.

The aniA gene of Neisseria gonorrhoeae encodes an outer membrane lipoprotein which is strongly induced when gonococci are grown anaerobically in vitro in the presence of nitrite. Database searches with the amino acid sequence derived from the aniA structural gene revealed significant homologies to copper-containing nitrite reductases from several denitrifying bacteria. We constructed an insertional mutation in the aniA locus of strain MS11 by allelic replacement, to determine whether this locus was necessary for growth in oxygen-depleted environments, and to demonstrate that AniA was indeed a nitrite reductase. The mutant was severely impaired in its ability to grow micro-aerophilically in the presence of nitrite, and we observed a loss in viability over several hours of incubation. No measurable nitrite reductase activity was detected in the aniA mutant strain, and activity in the strain with a wild-type locus was inducible. Finally, we report investigations to determine whether AniA protein is involved in gonococcal pathogenesis.

Alleles↗
PubMed1997

Autodisplay: one-component system for efficient surface display and release of soluble recombinant proteins from Escherichia coli.

The immunoglobulin A protease family of secreted proteins are derived from self-translocating polyprotein precursors which contain C-terminal domains promoting the translocation of the N-terminally attached passenger domains across gram-negative bacterial outer membranes. Computer predictions identified the C-terminal domain of the Escherichia coli adhesin involved in diffuse adherence (AIDA-I) as a member of the autotransporter family. A model of the beta-barrel structure, proposed to be responsible for outer membrane translocation, served as a basis for the construction of fusion proteins containing heterologous passengers. Autotransporter-mediated surface display (autodisplay) was investigated for the cholera toxin B subunit and the peptide antigen tag PEYFK. Up to 5% of total cellular protein was detectable in the outer membrane as passenger autotransporter fusion protein synthesized under control of the constitutive P(TK) promoter. Efficient presentation of the passenger domains was demonstrated in the outer membrane protease T-deficient (ompT) strain E. coli UT5600 and the ompT dsbA double mutant JK321. Surface exposure was ascertained by enzyme-linked immunosorbent assay, immunofluorescence microscopy, and immunogold electron microscopy using antisera specific for the passenger domains. In strain UT2300 (ompT+), the passenger domains were released from the cell surface by the OmpT protease at a novel specific cleavage site, R / V. Autodisplay represents a useful tool for future protein translocation studies with interesting biotechnological possibilities.

Adhesins, Escherichia coli↗
PubMed1997

Multifocal motor neuropathy.

A brief report of four patients with Multifocal Motor Neuropathy (MMN) two of whom improved with cyclophosphamide is presented. This is the first report of MMN from India.

Adult↗
PubMed1996

Absence of periplasmic DsbA oxidoreductase facilitates export of cysteine-containing passenger proteins to the Escherichia coli cell surface via the Iga beta autotransporter pathway.

The Iga beta autotransporter function of IgA1 protease from Neisseria gonorrhoeae was assessed in Escherichia coli using the Vibrio cholerae toxin B subunit (CtxB) as a heterologous passenger. N-terminal fusions with Iga beta of native CtxB or mutant CtxB protein containing no cysteines were constructed and analysed in isogenic E. coli mutants carrying defects in either or both the ompT (outer membrane protease T) and dsbA (periplasmic disulfide oxidoreductase) determinants. While export of the cystein-less CtxB passenger was independent of the dsbA genotype, the native CtxB passenger was properly translocated across the outer membrane only in the dsbA mutant background. This effect was consistent in the presence and in the absence of the OmpT protease which rather determined the release of surface-bound CtxB into the medium. Therefore, in agreement with previous observations Iga beta-dependent protein secretion requires an unfolded conformation of the passenger domain and can be blocked by disulfide loop formation in the presence of DsbA. Since DsbA acts in the periplasm, this provides evidence for a periplasmic intermediate in the Iga beta-mediated export pathway. E. coli (dsbA ompT) is highly suitable as a strain for the surface display of recombinant proteins via Iga beta, whether or not they contain cysteine residues.

Biological Transport↗
PubMed1995

Lack of effect of TNF antibodies on the cardiovascular sequelae of lipopolysaccharide infusion in conscious rats.

1. The aims of the present study were to determine the profile of tumour necrosis factor (TNF) release, and the effect of monoclonal antibodies to TNF, on the changes in regional haemodynamics and the responses to vasodilator and vasoconstrictor challenges, during a continuous 24 h low dose infusion of lipopolysaccharide (LPS) in conscious rats. 2. Male Long Evans rats were chronically instrumented for measurement of regional haemodynamics (renal, superior mesenteric and hindquarters) and were challenged with 3 min infusions of acetylcholine (22 nmol min-1), methoxamine (120 nmol min-1), salbutamol (0.83 nmol min-1) and bradykinin (14.4 nmol min-1). The rats were given either saline, or the TNF antibodies, TN3g1 or TN3g2a, 1 h before the start of a continuous infusion of LPS (150 micrograms kg-1 h-1) and were subsequently re-tested with the vasodilator and vasoconstrictor challenges 2, 6 and 24 h after the start of the LPS infusion. 3. Prior to infusion of LPS, TNF was not detectable in the plasma. During continuous infusion of LPS there was a transient elevation in plasma TNF levels, reaching a maximum (approximately 2300 pg ml-1) after approximately 1 h, and returning to undetectable levels after approximately 3 h of LPS infusion. 4. In the saline pretreated group, after 1-2 h of LPS infusion, there was a small hypotension and a marked renal vasodilation; 6 h after the start of LPS infusion there was a minor elevation in MAP above control levels, renal vasodilatation was maintained and a hindquarters vasoconstriction occurred; after 24 h of LPS infusion, there was a hypotension and renal and hindquarters vasodilatation. There were significant reductions in the tachycardic and renal vasodilator responses and an enhanced depressor response to acetylcholine after 24 h of LPS infusion. LPS infusion also caused a generalized hyporesponsiveness to the cardiovascular effects of methoxamine and salbutamol. The major changes in response to bradykinin were reduced tachycardic and enhanced depressor responses throughout the LPS infusion, a biphasic decrease and increase in renal conductance and enhanced hindquarters vasodilatation at 24 h. 5. Pretreatment with either TN3g1 or TN3g2a antibodies had no major effects on the changes in resting haemodynamics, or on the changes in response to methoxamine, salbutamol or bradykinin challenges during LPS infusion. However, the tachycardic responses to acetylcholine were generally preserved, and its hypotensive effect after 24 h of LPS infusion was not enhanced after TN3g1 or TN3g2a pretreatment. Thus, despite substantial, but transient, elevation of plasma TNF levels during continuous LPS infusion, it appears that the majority of cardiovascular changes were dependent on factors other than plasma TNF.

Acetylcholine↗
PubMed1994

Threonine is present instead of cysteine at the active site of urease from Staphylococcus xylosus.

DNA sequence analysis of the structural urease genes from Staphylococcus xylosus revealed that three enzyme subunits are encoded in the order of 11,000, 15,400 and 61,000 (mol. mass), which correspond to the single polypeptide chain of jack bean urease (90,800). Comparing the deduced amino acid sequence of S. xylosus urease with the amino acid sequence of jack bean urease an overall portion of 56% identical residues was found. For S. xylosus urease a subunit structure of (alpha beta gamma)4 was proposed, based on the comparison of the deduced amino acid content of the enzyme subunits with the total amino acid content of the purified enzyme. The staphylococcal enzyme contained no cysteine, as deduced from DNA sequence and confirmed by the determination of the total amino acid content in the purified enzyme. Instead of cysteine, known to be catalytically essential in the plant enzyme, and conserved among all bacterial ureases analyzed so far, threonine was found in S. xylosus. This amino acid-exchange was located within a highly conserved domain of 17 amino acids, supposed to be part of the active site. Sequence analysis of the respective region of Staphylococcus saprophyticus urease showed that it also contains threonine instead of cysteine. In contrast to jack bean urease S. xylosus urease was not affected by the SH-group inhibitor dipyridyl disulfide but was completely inhibited by the serine protease inhibitor phenylmethanesulfonyl fluoride. The presented results indicate that in these staphylococcal strains urea hydrolysis might function in a manner similar to the peptide bond cleavage by chymotrypsin.

Amino Acid Sequence↗
PubMed1991

Cloning and expression of various staphylococcal genes encoding urease in Staphylococcus carnosus.

The urease genes from Staphylococcus xylosus C2a, Staphylococcus aureus U500, and S. aureus Newman were cloned in Staphylococcus carnosus using the plasmid vectors pCA43 and pCA44. The resulting respective recombinant plasmids pUra 402, pUraUH66, and pUra17 contained chromosomal DNA fragments with sizes of 5.6, 5.8, and 6.8 kb, respectively. Investigations on urease expression of the donor and recombinant strains in media with various nitrogen sources revealed that S. xylosus C2a produced urease constitutively at the highest specific activity. All of the recombinant strains had significantly lower urease activities than their DNA-donor strains. The nickel-dependence of urease was demonstrated in S. aureus U500 by a plate diffusion assay.

Cloning, Molecular↗
PubMed1991

A colourimetric enzyme-linked sandwich assay for the detection of human platelets bound to a fibrinogen-coated surface.

A colourimetric enzyme-linked sandwich assay has been developed to investigate the binding of human platelets to fibrinogen. The presence of platelets bound to fibrinogen-coated plastic can easily be detected and quantitated. Platelets treated with chymotrypsin to expose the fibrinogen receptor, are fixed with paraformaldehyde, and stored frozen. The detection sandwich consists of a mouse monoclonal antibody directed against the human platelet CD9 antigen, and a rabbit anti-mouse immunoglobulin conjugated to the enzyme alkaline phosphatase. The cleavage of the phosphatase substrate p-nitrophenyl phosphate can be monitored colourimetrically. The data presented provide evidence that this method is capable of detecting platelet-fibrinogen binding in a physiologically relevant manner. The binding is inhibited by EDTA or excess fibrinogen. The fibrinogen alpha and gamma chain peptides, RGDS and LGGAKQAGDV, and the snake venom echistatin are also inhibitory with IC50 values of 135 microM, 1.8 mM and 100 nM respectively.

Blood Platelets↗
PubMed1990

Bacillus Calmette-Guérin-treated superficial bladder cancer: correlation of morphology with immunophenotyping.

Thirty-five biopsies from 19 patients with superficial transitional cell carcinoma of the bladder, treated with intravesical bacillus Calmette-Guérin (BCG), were assessed histologically and immunohistochemically. Pretreatment biopsies were available for comparison in all cases and five cases of non-specific cystitis were also examined. The inflammatory infiltrate was assessed with a streptavidin-biotin-peroxidase method using UCHL1, MT1, LN3, L26, HAM56, MAC387, Leu7 and anti-S100 in paraffin sections, and in 18 specimens were frozen tissues were available, Leu1, 2, 3, 4, 14, OKT10, HLA-DR and anti-Tac antibodies were applied. Post-treatment bladder biopsies showed severe oedema and a variable degree of inflammation. A granulomatous inflammation was seen in 11 cases, with granulomas present in six prostatic biopsies and acid-fast bacilli in two cases. The lymphoid infiltrate in all biopsies were largely T lymphocytes with a predominance of T helper cells present, often as a band-like infiltrate pressing against the residual epithelium, or the denuded bladder surface, and distributed in the vicinity of the granulomas. Activated lymphocytes were prominent in seven cases, although a moderate infiltrate of such cells was seen in all instances. Tac antigen was only occasionally expressed, and in a few NK cells were present among the infiltrates. In eight cases, HLA-DR was expressed in epithelial cells following BCG treatment, whereas all pre-treatment epithelial were negative.

Aged↗
PubMed1990

Infective endocarditis due to Streptococcus sanguis I occurring on a normal mitral valve.

We report a 64 year old lady in whom infective endocarditis of the mitral valve occurred with no previous underlying heart disease. Streptococcus sanguis I was isolated on blood culture and 2-D echo cardiography showed a vegetation on the anterior mitral leaflet. The viridans group of streptococci are classically associated with subacute endocarditis occurring on structurally abnormal valves, but involvement of a normal valve by these organisms is rare.

Echocardiography↗