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S L Stanley

Publications and source records attributed to S L Stanley.

70 records · Page 4Linked to original sources
PubMed1992

Serodiagnosis of invasive amebiasis using a recombinant Entamoeba histolytica antigen-based ELISA.

Amebic serology remains a critical component in the diagnosis of invasive amebiasis. A recombinant serine rich-Entamoeba histolytica-protein/maltose binding protein (SREHP/MBP) fusion protein was evaluated as the target antigen in an ELISA test to detect acute invasive amebiasis. Retrospective analysis of 65 serum samples from patients with amebic liver abscess and 40 asymptomatic control patients showed the SREHP/MBP ELISA test had a sensitivity of 74% and specificity of only 55% for the diagnosis of amebic liver abscess. This study was repeated under identical conditions using a purified recombinant SREHP cleaved from the MBP component. The purified recombinant SREHP-based ELISA had a sensitivity of 79% and specificity of 87%. Our data suggest a purified recombinant SREHP-based ELISA could prove useful in the serodiagnosis of acute invasive amebiasis.

Animals↗
PubMed1992

The role of newer antibiotics in gastroenterology.

The past decade has seen the introduction of a number of new potent antimicrobial agents, including broad-spectrum beta-lactam compounds such as the ureidopenicillins, third-generation cephalosporins, carbapenems, and monobactams; combinations of penicillins with inhibitors of beta-lactamase; and the quinolones. Most of these agents have excellent activity against enteric gram-negative rods and some are active against anaerobic organisms, the two bacterial groups most likely to be encountered in gastrointestinal infections. Despite the potency and wide spectrum of many of these new agents, there are currently relatively few clinical situations in which any of the newer antimicrobials are the first-line agents for therapy or prophylaxis of gastrointestinal diseases. Reluctance to use these agents as first-line therapy is based on concerns about the selection and spread of resistant organisms, superinfection syndromes, and the high cost of many of the newer agents. Specific clinical settings in which these agents may be given preference are as follows: 1. use of a third-generation cephalosporin (cefotaxime or ceftriaxone) in the treatment of spontaneous bacterial peritonitis. 2. use of broad-spectrum beta-lactam compounds to provide gram-negative coverage in patients who should not receive aminoglycosides 3. use of a third-generation cephalosporin (ceftriaxone) in the treatment of central nervous system relapses of Whipple's disease 4. use of quinolones for the empiric treatment of suspected bacterial diarrhea in patients sufficiently ill to require empiric initiation of antibiotics. 5. use of quinolones for the treatment of chronic carriers of Salmonella typhi 6. use of norfloxacin for prophylaxis against SBP. As further experience with these new antimicrobial agents is obtained and as more bacteria develop resistance to current first-line agents, there can be little doubt that these new antibiotics will play an increasing role in the prevention and treatment of gastrointestinal disease.

4-Quinolones↗
PubMed1991

Serodiagnosis of invasive amebiasis using a recombinant Entamoeba histolytica protein.

One hundred eight serum samples from 106 patients were examined by Western blot analysis for the presence of antibodies to a recombinant fusion protein containing the sequence of the newly described serine-rich Entamoeba histolytica protein (SREHP). Among patients with invasive amebiasis from Durban, Republic of South Africa; San Diego, Calif; Mexico City, Mexico; and St Louis, Mo, 53 (82%) of 65 had antibodies to SREHP. In contrast, only one patient (2%) of 43 without acute invasive amebiasis had antibodies to SREHP. The predictive value of a positive test for anti-SREHP antibodies in the detection of acute invasive amebiasis was most marked when analyzed in the patients from Durban, where 11 (92%) of 12 patients who were seropositive for SREHP had acute invasive amebiasis vs 17 (65%) of 26 patients who had a positive serologic diagnosis as determined by agar gel diffusion. The use of a serologic test based on the recombinant SREHP fusion protein may be a useful adjunct to the diagnosis of acute invasive amebiasis in endemic regions.

Amebiasis↗
PubMed1991

Isolation of a strain-specific Entamoeba histolytica cDNA clone.

Entamoeba histolytica is an intestinal parasite causing significant morbidity and mortality worldwide. More tools are needed to understand the epidemiology and molecular pathogenesis of amebiasis. A cDNA library was constructed by using poly(A)+ RNA isolated from an axenic strain of E. histolytica, HM1:IMSS, which expresses a pathogenic isoenzyme pattern (zymodeme). Differential screening of the library yielded a strain-specific 3' polyadenylated cDNA clone, C2, possessing nine 26-nucleotide tandem repeats. RNA and DNA transfer blot analysis of four axenic strains of E. histolytica possessing the same pathogenic zymodeme revealed that the gene is present and expressed in pathogenic E. histolytica HM1:IMSS and 200:NIH but is not present in pathogenic strains HK-9 and Rahman. In addition, Southern blot analysis using the C2 clone showed heterogeneity of genomic organization between HM1:IMSS and 200:NIH. DNA dot blot hybridization analysis demonstrated that cDNA clone C2 was also able to distinguish axenically cultured E. histolytica strains possessing pathogenic zymodemes from those possessing nonpathogenic zymodemes and could detect as few as 100 amebic trophozoites. We conclude that C2 is a strain-specific E. histolytica cDNA clone that, in conjunction with other E. histolytica-specific probes, could serve as a useful epidemiologic tool.

Animals↗
PubMed1990

Cloning and expression of a membrane antigen of Entamoeba histolytica possessing multiple tandem repeats.

Entamoeba histolytica causes amebic dysentery and amebic liver abscess, major causes of morbidity and mortality worldwide. We have used differential hybridization screening to isolate an E. histolytica-specific cDNA clone. The cDNA was found to encode a serine-rich E. histolytica protein (SREHP) containing multiple tandem repeats. The structural motif of SREHP resembles some of the repetitive antigens of malarial species, especially the circumsporozoite proteins. A recombinant trpE fusion protein containing the tandem repeats of SREHP was recognized by immune serum from a patient with amebiasis, demonstrating that SREHP is a naturally immunogenic protein. An antiserum raised against the recombinant fusion protein specifically bound to two distinct bands with apparent molecular masses of 46 and 52 kDa in a crude preparation of E. histolytica trophozoite membranes. This antiserum also inhibited E. histolytica trophozoite adhesion to Chinese hamster ovary cells in vitro. The ability to isolate E. histolytica-specific genes, and to express those genes in Escherichia coli, may be important in studying the molecular basis of E. histolytica pathogenesis and for the future development of vaccines.

Amino Acid Sequence↗
PubMed1989

Chinese hamster ovary cells deficient in N-acetylglucosaminyltransferase I activity are resistant to Entamoeba histolytica-mediated cytotoxicity.

To study the relationship between carbohydrate-specific amebic cytoadherence and ameba-mediated cytotoxicity, we measured Entamoeba histolytica trophozoite-mediated cytolysis directed against a panel of four Chinese hamster ovary (CHO) cell lines that have defined alterations in their glycosylation patterns. We recently measured amebic trophozoite adherence to this panel of CHO cells and showed that trophozoites bind variant cells (RICR 15B), which are deficient in Asn-linked N-acetyllactosamine units, at 12% of the level observed for wild-type cells (E. Li, A. Becker, and S. L. Stanley, J. Exp. Med 167:1725-1730, 1988). Using a 51Cr release assay to measure trophozoite-mediated cytolysis, we demonstrate in this study that RICR 15B cells are less susceptible to trophozoite-mediated cytolysis than are wild-type cells. In addition, we found that N-acetyllactosamine, which inhibits trophozoite adherence to CHO cells, also inhibited trophozoite-mediated cytolysis of wild-type cells. These studies indicate that surface carbohydrates on target cells can influence susceptibility to ameba-mediated cytotoxicity. This panel of CHO cells provides a useful model system for investigating the role of glycoconjugates in mediating amebic interactions with mammalian cells.

Acetylglucosaminidase↗
PubMed1988

Use of Chinese hamster ovary cells with altered glycosylation patterns to define the carbohydrate specificity of Entamoeba histolytica adhesion.

We compared the adherence of E. histolytica trophozoites with a panel of lectin-resistant CHO mutants with altered glycosylation patterns. Our results coupled with data from saccharide inhibition studies indicate that terminal N-acetyllactosamine units on Asn-linked complex type oligosaccharides provide the major determinants on the cellular receptor for E. histolytica adhesion.

Animals↗
PubMed1988

Antigen induced rheumatoid factors: characteristics of monoclonal rheumatoid factors produced after protein and carbohydrate immunization.

We generated a panel of monoclonal rheumatoid factors (MRF) from BALB/c mice immunized with ovalbumin, dextran or group-A-carbohydrate. Individual MRF were analyzed in terms of their binding to the four isotypes of murine IgG, isotypes of human IgG, and rabbit IgG, the idiotypes they express, and the VH gene families they employ. We found that antigen induced rheumatoid factors could be divided into three different families based on their isotypic specificity for murine IgG: an IgG1 binding family, and IgG3 binding family, and a family of MRF that bound all four murine isotypes. Rheumatoid factors belonging to all three families were isolated from mice immunized with carbohydrate antigens. The rheumatoid factors isolated from protein immunized mice all belonged to the IgG1 binding family. We were able to define two cross-reactive idiotypes among MRF, one expressed by a subgroup of the IgG1 binding family, and a second cross-reactive idiotype expressed by some members of the pan-binding family. We determined VH gene use in five of six MRF belonging to the IgG1 binding family and four of four members of the pan-binding family. Four of the IgG1 binding rheumatoid factors and three of the pan-binding rheumatoid factors utilize the J558 VH gene family. Rheumatoid factors produced after carbohydrate antigen immunization, as compared with those generated by protein immunization, are diverse in their isotypic specificity, and show a greater ability to bind heterologous IgG.

Animals↗
PubMed1987

Antigen-induced rheumatoid factors. Protein and carbohydrate antigens induce different rheumatoid factor responses.

Rheumatoid factors, autologous IgM anti-IgG, were produced after immunization with protein or carbohydrate antigens. After immunization with either type of antigen, the kinetics of the rheumatoid factor response reflected the kinetics of the dominant IgG isotype in the anti-antigen response. Secondary immunization with protein antigens induced an IgM rheumatoid factor response which was consistently greater than that seen after carbohydrate immunization, and almost exclusively specific for the IgG1 isotype. In contrast, primary or hyperimmunization with carbohydrate antigens gave rise to a more heterogeneous response dominated by IgM anti-IgG3, with lesser amounts of IgM anti-IgG2b and anti-IgG1. Direct immunization with immune complexes gave similar results, as complexes composed of IgG1 induced exclusively IgM anti-IgG1, whereas those complexes made up of IgG3 gave rise to IgM rheumatoid factors binding IgG3 and IgG2b. Rheumatoid factor production, with isotypic specificity defined by the immunizing antigen, appears to be a natural consequence of immunization with a variety of protein and carbohydrate antigens.

Animals↗
PubMed1981

Separation and characterization of neuronal and glial cell populations from embryonic chick cerebra in culture.

A new procedure of separation of glial and neuronal cell population from embryonic chick cerebra has been described and their morphology in vitro was examined by SEM. This technique used the differential adhesive properties of the glial and neuronal cells to obtain an initial separation in primary monolayer culture. The neuronal fraction was then further purified by treatment with cytosine arabinoside. The homogeneity of the glial and neuronal cultures produced by this technique was examined by phase contrast and scanning electron microscopy, liquid scintillation counting of incorporation of radioactive precursors into the cultured cells and autoradiographic study of the cultures. The purity of the neuronal culture was estimated to be better than 97 and 98% based on LSC and autoradiography respectively. The purity of glial culture was assessed by phase contrast and SEM and was estimated to have a purity of over 99%. The viability of the both cultures was good following initial separation. The glial cells were typically epitheloid and formed confluent monolayer 7--10 days after initial separation. These cells have a smooth upper surface and are typically hexagonal in shape. The neuronal cultures formed small aggregates interconnected with compound neuronal processes. It was noted that the neuronal differentiation was closely related to the glial cells. In the presence of a glial carpet, the aggregates became flattened and well differentiated neuronal cells were found. On the contrary, round neuronal aggregates were found. In the case of mixed cultures of glial and neuronal cells neurites were seen grown mainly on the surface of glial carpet. Only in rare occasions, neurites were seen bridging over the bare glass surface.

Animals↗
PubMedDate not supplied

Expression of the serine rich Entamoeba histolytica protein (SREHP) in the avirulent vaccine strain Salmonella typhi TY2 chi 4297 (delta cya delta crp delta asd): safety and immunogenicity in mice.

Infection by the intestinal protozoan parasite Entamoeba histolytica remains a significant threat to health in much of the world. Here we describe the successful expression of the serine rich Entamoeba histolytica protein (SREHP), a protective antigen of ameba, in an attenuated vaccine strain Salmonella typhi TY2 chi 4297 (delta cya delta crp delta asd). The attenuation of S. typhi TY2 chi 4297 was not altered by expression of the SREHP-maltose binding protein (MBP) fusion protein and mice parenterally vaccinated with S. typhi TY2 chi 4297 expressing SREHP-MBP developed serum anti-amebic and anti-LPS antibodies. S. typhi TY2 chi 4297 expressing SREHP-MBP represents a prototype combination vaccine designed to prevent both amebiasis and typhoid fever.

Animals↗
PubMedDate not supplied

Pneumococcal endocarditis: report of a series and review of the literature.

Pneumococcal endocarditis has declined sharply in incidence since the advent of penicillin but remains a potentially lethal infection. From 1980 to 1984, pneumococcal endocarditis was diagnosed in seven patients--four adults and three infants. Apart from one patient who had had a splenectomy, there were no recognizable predisposing factors to infection due to Streptococcus pneumoniae, although all three children were younger than 15 months of age. Congenital heart disease was present in two patients, calcific aortic disease in one, and mitral valve prolapse in a fourth. The remaining three patients had previously normal hearts. Meningitis occurred in five (71%) of the seven patients. Five patients were cured of their infection: four by medical therapy alone (penicillin or vancomycin), and a fifth, by medical therapy plus valvular debridement. Two patients died: one with intractable heart failure, and the second, from the complications of cardiac surgery. Penicillin alone is effective therapy for pneumococcal endocarditis. Patients unable to tolerate penicillin may be treated with vancomycin.

Adult↗
PubMedDate not supplied

Identification of immunogenic epitopes of the 170-kDa subunit adhesin of Entamoeba histolytica in patients with invasive amebiasis.

Entamoeba histolytica causes amebic dysentery (AD) and liver abscess (ALA). Little is known about protective immunity to amebiasis, and studies in this area have been complicated by the paucity of defined ameba antigens. We examined the proliferative responses of peripheral blood mononuclear cells (PBMC) from patients with AD and ALA to a recombinant protein containing a portion of the 170 kDa adhesin of E. histolytica (170CR), and to two synthetic peptides (1 and 2) derived from the 170 kDa sequence that were predicted to contain T cell epitopes. A significant number of patients with AD and ALA had PBMC that proliferated to 170CR molecule, and several individuals with ALA and AD had T cells that recognized one or both peptides. Contrarily, individuals from a non-endemic region for amebiasis did not respond to 170CR protein, or to both peptides. In regard to antibody response, nine of fifteen patients with ALA showed antibodies to 170CR protein. These same patients had antibodies to peptide 2. We identified peptides from 170-kDa adhesin that may contain both T and B cell epitopes recognized by some patients with invasive amebiasis. These peptides may be valuable reagents in studies of the immune response to amebiasis.

Adolescent↗