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Biomedical subjects

R W Bennett

Publications and source records attributed to R W Bennett.

At least 19 recordsLinked to original sources
PubMed2004

Natural atypical Listeria innocua strains with Listeria monocytogenes pathogenicity island 1 genes.

Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests. Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level. We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests. The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay. The results show that this isolate is indeed a novel one. Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain. This species, by definition, is typically nonhemolytic. The L. innocua isolate contains all the members of the PrfA-regulated virulence gene cluster (Listeria pathogenicity island 1) of L. monocytogenes. It is avirulent in the mouse pathogenicity test. Avirulence is likely at least partly due to the absence of the L. monocytogenes-specific allele of iap, as well as the absence of inlA, inlB, inlC, and daaA. At least two of the virulence cluster genes, hly and plcA, which encode the L. monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L. innocua strain. The detection by PCR assays of specific L. innocua genes (lin0198, lin0372, lin0419, lin0558, lin1068, lin1073, lin1074, lin2454, and lin2693) and noncoding intergenic regions (lin0454-lin0455 and nadA-lin2134) in the strain is consistent with its L. innocua DNA-DNA hybridization identity. Additional distinctly different hemolytic L. innocua strains were also studied.

Animals↗
PubMed1996

Staphylococcal food poisoning caused by imported canned mushrooms.

From February through April 1989, four outbreaks of staphylococcal food poisoning in the United States were associated with eating mushrooms canned in the People's Republic of China (PRC). In the four outbreaks, 99 persons who ate at a suspect facility developed gastrointestinal symptoms within 24 h, including 18 who were hospitalized. Illness was associated with eating mushrooms at a university cafeteria (relative risk [RR] = 53.0), a hospital cafeteria (RR = 13.8), a pizzeria (odds ratio [OR] = infinity), and a restaurant (OR = infinity) (all P < .0001). Staphylococcal enterotoxin A was found by ELISA in mushrooms at the sites of two outbreaks and in unopened cans from the three plants thought to have produced mushrooms implicated in outbreaks. These investigations led to multistate recalls and a US Food and Drug Administration order to restrict entry into the United States of all mushrooms produced in the PRC; until this action, the United States imported approximately 50 million pounds yearly.

Adult↗
PubMed1994

Application of pulsed-field gel electrophoresis to the epidemiological characterization of Staphylococcus intermedius implicated in a food-related outbreak.

An outbreak of food intoxication involving over 265 cases in western United States occurred in October 1991. Staphylococcus intermedius was implicated as the aetiologic agent. Representative outbreak isolates (five clinical and ten from foods) produced type A enterotoxin. DNA fragments generated by four restriction endonucleases and analysed by pulsed-field gel electrophoresis (PFGE) provided definitive evidence that all isolates from nine different counties in California and Nevada were derived from a single strain. The PFGE pattern of these outbreak isolates was distinct from those of a heterogeneous collection of seven S. intermedius strains of veterinary origin and five unrelated S. aureus laboratory strains. The data show a significant PFGE pattern heterogeneity not only among members of different Staphylococcus species but also within members of the same species and even the same enterotoxin type. The results indicate that PFGE is a valuable strain-specific discriminator for the epidemiological characterization of S. intermedius. To our knowledge, this represents the first documented foodborne outbreak caused by S. intermedius. These findings suggest that the presence of S. intermedius and other species such as S. hyicus in food should be reason for concern.

Butter↗
PubMed1994

A comparison of ELISA and RPLA for detection of Bacillus cereus diarrhoeal enterotoxin.

Fourteen strains of Bacillus cereus isolated from different sources were examined for their ability to produce diarrhoeal enterotoxin by two commercial immunoassay kits (Oxoid BCET-RPLA and Tecra ELISA) and the microslide immunodiffusion assay. One strain that was positive in monkey feedings, as well as a number of other strains isolated from diarrhoeal outbreaks, gave positive results in the ELISA and negative results in the RPLA test systems. When tested in the microslide assay, these strains produced only one antigen which formed a line of identity with the reference toxin. The results of the control toxins provided with the kits substantiated that the two commercial assays did not detect the same antigen. Cultures positive with both assay kits were shown to produce diarrhoeal enterotoxin (by a line of identity) and other antigens in the microslide immunodiffusion assay.

Antigens, Bacterial↗
PubMed1984

Stages IE and IIE non-Hodgkin's lymphomas of the stomach. Comparison of treatment modalities.

Seventy-nine patients with Stages IE and IIE non-Hodgkin's lymphomas of the stomach were treated between 1953 and 1980. The histopathologic classification was as follows: diffuse large cell, 61 (of which 23 were immunoblastic sarcomas [plasmacytoid]); diffuse well-differentiated lymphocytic, 6; diffuse mixed, 1; undifferentiated non-Burkitt's, 1; nodular, 9; and unclassifiable, 1. Thirty-five patients had Stage IE disease and 44 had Stage IIE. Treatment modalities included surgery, radiotherapy, chemotherapy, and combinations thereof. Sixty-six patients had a laparotomy for diagnosis and/or management. Of these, only 42 had a gastrectomy. The stomach was considered to be unresectable in the other 24 patients. There were 5 postoperative deaths among 31 patients who had a laparotomy or gastrectomy at our institution. The overall 5-year actuarial survival was 56%; the disease-free survival was 54%. For patients with Stage IE disease the survival was 76%, and for those with Stage IIE, 42%. Promising results were obtained in 13 patients who were treated on a multimodality program consisting of four cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus bleomycin (Bleo), which was alternated with involved field radiotherapy. All 13 patients had no evidence of disease as of this report. Only one patient had a relapse (Waldeyer's ring), and he was salvaged with radiotherapy. Six of these 13 were diagnosed by endoscopic biopsy and did not have a laparotomy, 3 were found to have unresectable disease at laparotomy, and 4 had a resection. Biopsy with the flexible fiberscope and treatment with CHOP-Bleo and radiotherapy can avoid the morbidity and mortality of gastrectomy.

Adult↗
PubMed1984

Development of a monoclonal antibody capable of interacting with five serotypes of Staphylococcus aureus enterotoxin.

A monoclonal antibody capable of binding to determinants shared in common by staphylococcal enterotoxin serotypes A, B, C1, D, and E was developed. To accomplish this, BALB/c mice were immunized by alternating injections of serotypes A and D to enrich for spleen lymphocytes programmed to produce antibody to possible common determinants. These cells, fused with mutant myeloma cells (P3-X-63Ag8.653) produced hybrids that formed monoclonal antibodies to either serotype A only or to both serotypes A and D. A cloned hybridoma from the latter group produced an antibody (subclass immunoglobulin G1) which interacted with five serotypes. Highest affinity was to B and C1. An immunomatrix consisting of this antibody cross-linked to protein A-Sepharose CL-4B with dimethyl pimelimidate was capable of binding enterotoxin. Bound toxin was eluted with diethylamine. Because of its ability to interact with all five serotypes, the monoclonal antibody should prove useful in the development of a rapid method for screening foods for the presence of staphylococcal enterotoxin.

Animals↗
PubMed1983

High-performance liquid chromatography of staphylococcal enterotoxin B.

Size-exclusion, ion-exchange, and reversed-phase chromatography were investigated for use in purification and characterization of Staphylococcal enterotoxin B (SEB), a 28,000 Mr protein associated with Staphylococcal food-borne intoxication. In all approaches chromatography of crude or purified SEB yielded one or more components which displayed toxin activity and contained the 28,000 Mr SEB protein plus other lower-molecular-weight protein species. Reversed-phase chromatography of detergent-treated SEB permitted resolution of the 28,000 Mr protein from lower-molecular-weight components.

Bacterial Proteins↗
PubMed1983

Tumor-associated gastroparesis: correction with metoclopramide.

Little is known about gastric emptying or its importance in the feeding disorders of cancer patients. In 70 percent of patients with upper gastrointestinal tumors who complained of satiety and postprandial fullness, gastric emptying was prolonged, as measured by a radioisotopic method. Metoclopramide was studied prospectively in 10 patients with unresectable upper gastrointestinal neoplasia and tumor-related gastroparesis. All patients had measurable subjective improvement with the therapy. There was a high correlation between objective improvement in gastric emptying and higher symptom scores after therapy. Results of baseline gastric emptying studies were predictive of therapeutic response. Requirements for hospitalization and antinauseants were reduced in all patients. Patients in whom response was positive gained weight and were able to take advantage of specific tumor therapies in an outpatient setting. Metoclopramide is a useful adjunct to the palliative regimen extended to patients with upper gastrointestinal tumors.

Adult↗
PubMed1980

Extraction and separation of staphylococcal enterotoxin in foods: collaborative study.

A study was performed by 15 collaborators on a method for the extraction and chromatographic separation of Staphylococcus aureus enterotoxins from foods. Enterotoxin types A--E were added to crabmeat, milk, ground beef, and potato. Evaluation of the method was based on solubility of food eluates after extraction and separation of the enterotoxin; efficiency of recovery of enterotoxins A--E from foods; and serological categorizing of foods, as determined by the presence or absence of enterotoxins in the 8 food samples studied. The collaborative results on sample solubility, detection and identification of enterotoxin in foods, and differentiation of toxic from nontoxic samples showed overall positive rates of 94.79, 72.69, and 99.23%, respectively. The method, which has been substantiated by statistical evaluation, appears to be effective for the separation of staphylococcal enterotoxins from foods. The Association has adopted the method as official first action and no adverse comments have been received.

Animals↗
PubMed1977

Statistical inference as applied to bioavailability data--a guide for the practicing pharmacist.

Descriptive statistics and statistical tests used in reporting bioavailability data are reviewed in order to give the practicing pharmacist the fundamental knowledge needed to evaluate such data. Using acetaminophen bioavailability data as a model the following concepts are explained: mean, median, mode, standard deviation, range, 95% confidence limit, Student's t-test, analysis of variance, and the Wilcoxon rank sum test.

Acetaminophen↗
PubMed1976

Collaborative study of the serological identification of staphylococcal enterotoxins by the microslide gel double diffusion test.

A collaborative study was conducted, using the microslide gel double diffusion test for enterotoxin detection by determining the staphylococcal enterotoxigenicity of 7 strains of Staphylococcus aureus. Two strains produced staphylococcal enterotoxin A (SEA), 2 strains produced staphylococcal enterotoxin B (SEB), one strain produced both SEA and SEB, and 2 strains produced neither SEA nor SEB. To ascertain the effectiveness of this method for the detection of enterotoxins, strains of enterotoxigenic staphylococci which produced small or relatively large amounts of toxin were used in the study. The cultures were grown on semi-solid brain-heart infusion agar and the culture fluids were assayed serologically for SEA and SEB. The qualitative results of this study by 16 collaborators indicated that this technique, in general, demonstrated a high degree of specificity as well as simplicity and reproducibility in the identification of the enterotoxins. Of the 16 participating laboratories, 14 reported the correct diagnoses for the 7 staphylococcal strains studied and 2 laboratories determined 6 of the 7 strains correctly. Based on these results, this method has been adopted as official first action.

Culture Media↗