PubMed Health⌕ Search

Biomedical subjects

S W Joseph

Publications and source records attributed to S W Joseph.

At least 37 records · Page 2Linked to original sources
PubMed1993

Murine T-cell response to native and recombinant protein antigens of Rickettsia tsutsugamushi.

A polyclonal T-cell line with TH1 characteristics was used to assess the murine cellular immune response to native and recombinant Rickettsia tsutsugamushi antigens. Proliferation of this T-cell line was observed in response to numerous native antigen fractions, which indicates that the murine T-helper-cell response is directed at multiple scrub typhus antigens with no apparent antigenic immunodominance. Subsequent analysis of recombinant R. tsutsugamushi antigens made it possible to identify a 47-kDa scrub typhus antigen (Sta47) that was stimulatory for the polyclonal T-cell line. Recombinant clones encoding 56-, 58-, and 110-kDa antigens (Sta56, Sta58, and Sta110, respectively) were unable to induce proliferation of this T-cell line. DNA sequence analysis of the cloned rickettsial insert encoding the Sta47 protein revealed the presence of four open reading frames potentially encoding proteins of 47, 30, 18, and 13 kDa. Analysis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated and eluted fractions of lysates from the recombinant HB101(pRTS47B4.3) demonstrated that the fractions containing the 47-kDa protein as well as those containing proteins less than 18 kDa were stimulatory. Selected synthetic amphipathic peptides derived from the Sta47 antigen sequence identified a 20-amino-acid peptide that gave a 10-fold increase in T-cell proliferation over a control malarial peptide of similar length. Recognition of the 47-kDa antigen by a T-cell line with TH1 characteristics implicates this protein as one of potential importance in protection studies and future vaccine development.

Amino Acid Sequence↗
PubMed1992

Molecular studies on the aerolysin gene of Aeromonas species and discovery of a species-specific probe for Aeromonas trota species nova.

A large group of aeromonads and other enteric microorganisms were assayed for the presence of the aerolysin gene with use of DNA-DNA hybridization. Two DNA fragments corresponding to the regulatory region (aerC) and the structural gene (aerA) were used as probes for the detection of the aerolysin gene in these strains. Sequences corresponding to the aerolysin structural gene were widespread among Aeromonas isolates. In contrast, the aerC probe was much more selective, and sequences corresponding to the aerC region were detected in only a small subset of strains. Concurrent studies using numerical taxonomy and DNA hybridization with the aerC probe on a larger set of strains led to the identification of a distinct cluster of 14 presumed atypical Aeromonas sobria strains. These strains have recently been grouped into a new species designated Aeromonas trota. Hence, the DNA fragment aerC used in the study is a species-specific gene probe for A. trota. The ability of the aerC probe to detect strains belonging to a single species suggests that there is selection pressure to maintain the clonality of this species. These results have important implications with respect to the evolution of "pathogenic profiles" among these medically important bacteria.

Aeromonas↗
PubMed1991

Aeromonas update: new species and global distribution.

There are currently eight proposed or validated Aeromonas spp. of which five have been implicated in human disease: A. hydrophila, A. sobria, A. caviae, A. veronii, and A. schubertii. Recent studies have extended the geographic distribution and source of isolation of the newer species and resulted in the possibility of two new species, A. jandaei and A. trota, from diarrheal, wound, blood and environmental sources.

Aeromonas↗
PubMed1991

Molecular cloning and sequence analysis of a Rickettsia tsutsugamushi 22 kDa antigen containing B- and T-cell epitopes.

The identification of Rickettsia tsutsugamushi T-cell epitopes is necessary for the characterization of the protective immune response (of which the T-cell response is essential) against scrub typhus rickettsiae. A T-helper cell line derived from R. tsutsugamushi (Karp strain) immune mice reacted with rickettsial protein antigens eluted from the 18-35 kDa region of polyacrylamide gels. Within this region is a 22 kDa protein which is reactive with immune serum. The gene encoding the 22 kDa scrub typhus antigen (sta22) was cloned and expressed in Escherichia coli. Nucleotide sequence analysis of the sta22 gene revealed a potential open reading frame (ORF) in the sta22 sequence encoding a 22 kDa protein. A recombinant 22 kDa protein synthesized in E. coli maxicells was reactive with anti-rickettsial antibodies. The codon usage of the adenine and thymine rich sta22 sequence was similar to other previously sequenced R. tsutsugamushi genes. Computer analysis of the deduced amino acid sequence suggested that the Sta22 protein has several amphipathic regions which may be potential T-cell epitopes. The recombinant Sta22 protein eluted from polyacrylamide gels induced a strong proliferative response from the scrub typhus rickettsiae reactive T-cell line. Recognition of the R. tsutsugamushi Sta22 polypeptide by both cellular and humoral immune mechanisms implicates this antigen as one of potential importance in vaccine development.

Amino Acid Sequence↗
PubMed1991

Aerokey II: a flexible key for identifying clinical Aeromonas species.

A small subset (n = 18) of highly discriminatory tests was derived from the feature frequency of 50 tests used in the study of 167 predominantly clinical Aeromonas strains. Seven of these eighteen tests were used to construct a flexible, dichotomous key, Aerokey II, for identifying clinical aerontonads: esculin hydrolysis, gas from glucose, acid from arabinose, indole production, acid from sucrose, Voges-Proskauer reaction, and resistance to cephalothin (30 micrograms). This schema was initially evaluated in a single-blind trial of 60 well-characterized clinical Aeromonas hydrophila (n = 21), A. caviae (n = 19), and A. veronii bv. sobria (n = 20) strains from an independent laboratory. Of the 60 strains tested, 58 (97%) were accurately identified to the species level. Aerokey II was further evaluated with 18 additional American Type Culture Collection and reference strains representing the more recently proposed taxa A. veronii bv. veronii, A. schubertii, A. jandaei, and A. trota and accurately identified all of these strains.

Aeromonas↗
PubMed1991

Aeromonas jandaei (formerly genospecies DNA group 9 A. sobria), a new sucrose-negative species isolated from clinical specimens.

A large numerical taxonomy study conducted in 1988 of 165 mostly clinical Aeromonas strains from diverse geographic sources produced a cluster (S = 84%, SSM) of four sucrose-negative strains that included the DNA definition strain for DNA group 9 A. sobria (CDC 0787-80). These four strains, together with five additional strains received in 1989, were subjected to DNA-DNA hybridization (hydroxyapatite, 32P, 60 and 75 degrees C), and all eight strains were closely related to the ninth labeled DNA group 9 definition strain CDC 0787-80 (73 to 86% relatedness at 60 degrees C and 68 to 80% relatedness at 75 degrees C; percent divergence, 2.0 to 3.5). Type strains and DNA definition strains for all other established Aeromonas species were only 35 to 72% related (60 degrees C) to CDC 0787-80. We propose the name Aeromonas jandaei for this highly related group of nine strains, formerly known as DNA group 9 A. sobria. The type strain was designated ATCC 49568 (CDC 0787-80). The nine strains were examined at 36 degrees C and were found to be resistant to 0/129 (vibriostatic agent) and uniformly positive for oxidase, gas production from glucose, indole, lysine decarboxylase, arginine dihydrolase, o-nitrophenyl-beta-D-galactopyranoside, motility (25 degrees C), nitrate reduction, citrate utilization, hemolysis on sheep blood agar, and growth in Trypticase soy broth with no added NaCl. They all fermented D-glucose, D-mannitol, and mannose but did not ferment sucrose, cellobiose, L-arabinose, inositol, salicin, or D-sorbitol. They were uniformly negative for esculin and urea hydrolysis, elastase production, ornithine decarboxylation, and the string test. The antibiogram of A. jandaei resembled that of other aeromonads (resistance to ampicillin and cephalothin), but it differed from most other aeromonads because of resistance to single dilution of colistin and differed from clinical A. veronii biogroup sorbria (formerly A. sobria) by its nearly uniform resistance to cephalothin. The esculin-, sucrose-, and cellobiose-negative and colistin-resistant profile distinguished A. jandaei from other Aeromonas species. These A. jandaei strains were isolated from blood (two strains), wounds (two strains), diarrheal stools (four strains), and a prawn (one strain). The blood and wound isolates, in particular, suggest that there is a possible clinical significance for this species and justify identification of and further research on this group of motile aeromonads.

Aeromonas↗
PubMed1991

Aeromonas jandaei and Aeromonas veronii dual infection of a human wound following aquatic exposure.

Exudate removed from an infection that developed below the left eye of a 10-year-old male following a previously inflicted wound after aquatic exposure was cultured and revealed two different Aeromonas spp. Further characterization showed that one strain was phenotypically identical to Aeromonas veronii, while the other strain was confirmed by DNA hybridization analysis to be Aeromonas jandaei sp. nov. This is the first report of these more recently described aeromonads, thus far rarely reported from clinical disease, occurring simultaneously in a human infection.

Aeromonas↗
PubMed1991

Aeromonas trota sp. nov., an ampicillin-susceptible species isolated from clinical specimens.

Previous DNA hybridization studies established 12 Aeromonas genospecies, from which nine phenotypic species have been proposed: Aeromonas hydrophila, A. sobria, A. caviae, A. media, A. veronii, A. schubertii, A. salmonicida, A. eucrenophila, and A. jandaei. We have delineated a new Aeromonas genospecies, A. trota, on the basis of 13 strains isolated primarily from fecal specimens from southern and southeastern Asia. All strains were highly related to the proposed type strain, AH2 (ATCC 49657T): 51 to 100% (60 degrees C) and 49 to 99% (75 degrees C), with 0.2 to 2.2 divergence. AH2 was only 16 to 41% (60 degrees C) related to all other Aeromonas type strains and DNA group definition strains. The unique profile of A. trota includes negative reactions for esculin hydrolysis, arabinose fermentation, and the Voges-Proskauer test, positive reactions for cellobiose fermentation, lysine decarboxylation, and citrate utilization, and susceptibility to ampicillin, as determined by the broth microdilution MIC method and the Bauer-Kirby disk diffusion method (10 micrograms). Nine of the A. trota strains were from a single study of 165 geographically diverse aeromonads. This finding questions the efficacy of screening fecal specimens for Aeromonas spp. with ampicillin-containing media and suggests a previously unrecognized prevalence of this new species.

Aeromonas↗
PubMed1989

Characterization of Aeromonas schubertii strains recently isolated from traumatic wound infections.

Recent studies have resulted in the proposal of a new species, Aeromonas schubertii (mannitol, sucrose, and indole negative), formerly termed Enteric Group 501, on the basis of the study of seven strains isolated from the southeastern and southwestern United States and Puerto Rico. We have isolated two phenotypically similar A. schubertii strains from infected human wounds sustained in the Chesapeake Bay area. Their identification was confirmed by DNA-DNA hybridization to the Centers for Disease Control definition strain 2446-81 (ATCC 43700) for group 12. The strains were further examined for the presence of virulence-associated markers: hemolysin, hemagglutinins, cytotoxin production, agglutination in acriflavine, resistance to normal human serum, and autoagglutination phenotype. Both strains were positive for hemolysin by the plate assay, cytotoxin production at 1:10, and DNase and protease. They were resistant to human serum and negative for acriflavine agglutination, and only one of the strains was autoagglutination positive. Both strains were negative for cell-free hemolysin, hemagglutinins, pectinase, and chitinase. These isolations of A. schubertii further extend its previously described geographic distribution and reinforce its role as a primary causative agent of cellulitis with possible increased antimicrobial resistance.

Aeromonas↗
PubMed1989

Species identification of Aeromonas strains based on carbon substrate oxidation profiles.

Twenty clinical strains each of Aeromonas hydrophila, Aeromonas caviae, and Aeromonas sobria were evaluated for their abilities to oxidize one or more of 95 carbon sources on a GN Microplate (BIOLOG, Hayward, Calif.). Nine substrates yielded good, discriminatory values for the three species tested. The panel appears to be useful for the species identification of Aeromonas isolates originating from human material.

Aeromonas↗
PubMed1988

Enzymatic characterization of three aeromonas species using API Peptidase, API "Osidase," and API Esterase test kits.

An enzymatic characterization of 16 strains of Aeromonas species including A. hydrophila (7), A. sobria (5), and A. caviae (4) was carried out using API Peptidase (strips numbered 1, 2, 3, 4, 5, and 6); API Esterase and API "Osidase" test strips. A total of 89 substrates was used in the assay and included 59 arylamides (aminopeptides), 10 esters, and 20 carbohydrates. All three species were remarkably uniform in their reactivities. Nineteen (32%) of the arylamide substrates used were hydrolyzed by all three species. Very strong arylamidase activity was displayed by all three species for L-lysine, L-hydroxyproline, L-arginine, L-alanine, L-proline, and L-leucyl-L-alanine. Esterase activity was strongest against caproate (C6), caprylate (C8), nonanoate (C9), and caprate (C10) substrates. Only a limited number of carbohydrate substrates were hydrolyzed; strong N-acetyl-beta-D-glucosaminidase activity was given by all strains. Both A. hydrophila and A. caviae gave strong beta-D-glucosidase reactivities, while A. sobria appeared to be negative for this enzyme. The results of our preliminary study show that some of the enzymes examined may be useful in the identification and differentiation of these species. The API enzyme assays yielded rapid (4 hr) results. The assays were easy to perform, relatively inexpensive and reproducible. The importance of replicate testing and the inclusion of uninoculated (buffer only) controls as part of the assay is emphasized.

Aeromonas↗
PubMed1987

Acute respiratory disease associated with influenza epidemics in Houston, 1981-1983.

Virological surveillance at "sentinel" clinics in Houston has demonstrated that the annual peak in the number of visits for acute respiratory disease (ARD) always coincides with the peak of influenza virus activity. A survey of visits to a health maintenance organization between 1981 and 1983 allowed us to calculate the age-specific rates of visits for ARD during two moderately severe influenza epidemics (1981-1982 and 1982-1983). During the most intense period of influenza virus activity the rate of visits for ARD was about 12 per 100 persons; the risk of developing ARD was greatest for preschool children (1981-1982, 27 per 100; 1982-1983, 29 per 100) and averaged about 10 per 100 for persons greater than 10 years of age. The risk of hospitalization with ARD was about 10 per 10,000 persons for residents of Harris County (Texas) during the same epidemics and was greatest for persons greater than 65 years of age.

Adolescent↗
PubMed1985

Characterization and distribution of Vibrio alginolyticus and Vibrio parahaemolyticus isolated in Indonesia.

Previous studies have shown that Vibrio alginolyticus and Vibrio parahaemolyticus can be isolated from similar types of marine samples. In this report, the results of an examination of 567 V. alginolyticus and V. parahaemolyticus strains, isolated from seawater in Jakarta Bay and from more than 30 types of seafood from markets in Jakarta, Indonesia, are presented. Most isolates were from mackerel, shrimp, or squid. Numerical taxonomic analyses clustered 337 isolates and three V. alginolyticus reference strains at S greater than or equal to 80%. These strains produced acid from sucrose, but only approximately 80% produced acetoin or grew in the presence of 10% NaCl. The frequency of occurrence of V. alginolyticus in seawater samples ranged from 0% (in February and March 1972) to 100% (in September and December 1972) and was highest in seafood samples from August to December 1972. A second cluster of 230 isolates and seven V. parahaemolyticus reference strains was observed at S greater than or equal to 82%. These strains did not produce acetoin or acid from sucrose, and approximately 20% grew in the presence of 10% NaCl. V. parahaemolyticus was detected in seawater samples each month, with the highest frequency of occurrence (83.3%) in May 1972. Twenty-nine K antigen serotypes were demonstrated in V. parahaemolyticus isolates, and another 40% were untypable. The modal antibiotic resistance pattern for each species included five drugs. Only 12% of the V. parahaemolyticus strains were Kanagawa positive, and 10% elicited fluid accumulation in ligated rabbit ileal loops. All of the 7 V. alginolyticus strains and 94 (70%) of the V. parahaemolyticus strains tested killed mice when inoculated intraperitoneally.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Enhancement of Vibrio parahaemolyticus virulence by lysed erythrocyte factor and iron.

The effect of lysed blood on the virulence of Vibrio parahaemolyticus for mice was investigated. A factor present in lysed erythrocytes was found to greatly reduce the 50% lethal dose of V. parahaemolyticus for mice. Similar effects were observed with ferric ammonium citrate and manganous sulfate. V. parahaemolyticus grown in brain heart infusion containing lysed erythrocyte factor appeared to produce a lethal toxin which was either inapparent or absent when the organism was grown in brain heart infusion alone.

Animals↗