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Biomedical subjects

T W Chang

Publications and source records attributed to T W Chang.

At least 127 records · Page 7Linked to original sources
PubMed1978

Comparison of five regimens for treatment of experimental clindamycin-associated colitis.

The hamster model of clindamycin-induced enterocolitis was studied to determine the natural course of the disease and the response to five therapeutic regimens. Tissue culture assays of stools from untreated animals showed that colitis toxin is present at low titers within 24--36 hr after challenge with clindamycin; titers of toxin in subsequent specimens of stool increased progressively until the animals died on days 2--4 after challenge. Therapeutic regimens tested in this model were initiated 24 hr after clindamycin challenge when the majority of the animals had evidence of colitis toxin. Methylprednisilone, an anion exchange resin, and gas gangrene polyvalent antitoxin had a minimal effect on toxin titers in stool and failed to delay substantially death due to enterocolitis. Vancomycin and tetracycline eliminated toxin in stools and delayed death. However, the salutary effects of these antibiotics were noted only during the course of their administration since all animals died of enterocolitis and had high titers of toxin when treatment was discontinued.

Animals↗
PubMed1978

Treatment with levamisole of recurrent herpes genitalis.

A double-blind study was carried out to investigate the possibility of therapeutic effect of levamisole on recurrent progenital herpes. One hundred and nine patients, including 53 females, entered the study, but only 75 completed. Levamisole, 50 mg three times daily for 3 days, was started at the first sign of recurrence. The study period consisted of 6 visits or 12 months, whichever came first. No statistical differences were observed between levamisole and placebo groups when comparing the duration of the lesion and the degree of pain, although less pain was observed among those on levamisole. The interval between attacks was increasingly prolonged in the levamisole-treated group, and reached a significant level at the sixth visit. However, analysis on the basis of mean cumulative number of days between attacks showed no significant differences throughout the study period. Because of occasional neutropenia and generalized urticaria, and because of the absence of clear-cut clinical improvement of statistical significance, levamisole was considered of limited benefit to patients with recurrent genital herpes infection.

Adult↗
PubMed1978

Clindamycin-induced enterocolitis in hamsters as a model of pseudomembranous colitis in patients.

Stools from a patient with antibiotic-associated colitis and cecal contents from a hamster with clindamycin-induced enterocolitis were compared in a cytotoxicity assay to determine common properties. Both specimens produced actinomorphic changes in human amnion cells at 10(-7) dilutions. The toxin was acid labile, heat labile, nonether extractable, non-dialyzable, and produced maximum activity at 60% with ammonium sulfate precipitation. Cytotoxicity was neutralized with clostridial antitoxin but not with equine serum. Clostridium difficile was recovered in high concentrations in specimens from both the hamster and patients. The supernatants of these C. difficile strains produced cytoxic effects which were also neutralized by clostridial antitoxins. These results indicate that clindamycin-induced enterocolitis in hamsters is a model of human disease and implicate toxin-producing clostridia as responsible agents.

Animals↗
PubMed1978

Neutralization of Clostridium difficile toxin by Clostridium sordellii antitoxins.

Neutralization of Clostridium difficile toxin by Clostridium sordellii antitoxin was studied by cytotoxicity assay in tissue culture. The sources of toxin were stools from two patients with pseudomembranous colitis and a culture filtrate of C. difficile isolated from one of the patients. C. sordellii antitoxin was available either in monovalent form or as gas gangrene polyvalent antitoxin. The potency of antitoxins against C. difficile determined by cytotoxicity assay did not correlate with the established values reported for mouse protection tests against C. sordellii toxin. An equivalent zone of optimal neutralization was demonstrated for stool toxin, and a slightly different one for culture toxin. The rate of neutralization appeared to be instantaneous, either at 24 or at 37 degrees C. The efficacy of antitoxin in preventing cytotoxicity in cultured cells preexposed to toxin decreased rapidly with preexposure time. The union between toxin and antitoxin could be readily dissociated by simple dilution or by ammonium sulfate precipitation followed by dissociated by simple dilution or by ammonium sulfate precipitation followed by dilution. Continued incubation of toxin-antitoxin mixture did not increase the firmness of the union; on the contrary, more dissociation occurred. The unusual looseness of the toxin-antitoxin union is probably relatd to lack of serological specificity or affinity. Based on these observations, a practical diagnostic method for antibiotic-induced colitis is outlined.

Antitoxins↗
PubMed1978

Antibiotic-induced lethal enterocolitis in hamsters: studies with eleven agents and evidence to support the pathogenic role of toxin-producing Clostridia.

Clindamycin-induced enterocolitis in hamsters was studied, using a tissue culture assay to detect clostridial toxin. It was found that animals with lethal enterocolitis had a cytopathogenic substance in cecal contents and blood that was neutralized by clostridial antitoxins. Cultures of the cecal flora yielded numerous species of clostridia, but only 1 organism was detected which produced a toxin which was cytopathic in tissue culture. This organism, Clostridium difficile, was consistently present in high concentrations, and the cell-free supernate of these strains caused enterocolitis if injected intracecally into hamsters. Ten additional antimicrobials were tested ih hamsters. Ampicillin, vancomycin, erythromycin, cephalosporins, and oral gentamicin caused lethal enterocolitis in most recipients, and all animals which died had evidence of clostridia toxin in cecal contents at necropsy. Tetracycline and metronidazole were well tolerated, and the animals given these antimicrobials had no evidence of the toxin. We conclude that toxin-producing clostridia are responsible for lethal enterocolitis due to a variety of antimicrobials in hamsters.

Ampicillin↗
PubMed1978

Role of Clostridium difficile in antibiotic-associated pseudomembranous colitis.

Tissue cultures were performed on stools from 189 patients to detect a cytopathic toxin which is neutralized by Clostridium sordellii antitoxin. Specimens satisfying these criteria were considered positive in the tissue culture assay. Stools from 26 of 27 patients with antibiotic-associated pseudomembranous colitis were positive and 16 of these specimens showed toxin titers of 10(-3) dilutions or greater. The tissue culture assay was positive with specimens from 9 of 63 patients with antibiotic-associated diarrhea without documented pseudomembrane formation. Stools from patients with neonatal necrotizing enterocolitis, ulcerative colitis, and healthy controls were uniformly negative in this assay. Cultures were performed on stools from 38 patients with antibiotic-associated diarrhea or colitis to detect clostridia which produce a cytopathic toxin in vitro. Clostridium difficile was recovered from 6 of 8 specimens which were positive in the tissue culture assay and 5 of 30 which were negative in this assay. C. sordellii was recovered in a single specimen. One hundred and nine clostridia strains were tested in the tissue culture assay and C. difficile was the only species which produced a cytopathic toxin. All strains of this organism were positive in the tissue culture assay and, in each instance, cytotoxicity was neutralized by C. sordellii antitoxin. These results indicate that C. difficile is the major cause of antibiotic-associated pseudomembranous colitis and offer an explanation for previous studies showing that the cytotoxin of stools from these patients is neutralized by C, sordellii antitoxin.

Anti-Bacterial Agents↗
PubMed1977

Primary and recurrent herpetic whitlow.

Herpetic whitlow has been reported as a cross-infection among personnel working in clinics or hospitals. Vesicles or bullae suggest the diagnosis; confirmation is by virus isolation. Eight cases in medical personnel whose duties included contact with the oral cavity of infected patients were seen within a period of 3 years. The disease started as a paronychia in 3 instances, but involvement of the pulp space was the rule. Radiating pain along the C7 distribution was noted in 4 patients. Numbness and hypoesthesia following the acute episode were observed in one patient. Two individuals suffered recurrent attacks of herpetic whitlow at the same site.

Adult↗
PubMed1976

Familial allergic seminal vulvovaginitis.

Vulvovaginal reactions to seminal fluid occurred in all four women in a family. The reactions consisted of stinging, burning, and pain in the vagina, starting during coitus or immediately after ejaculation, and persisting for 2 to 72 hours. The vagina and vulva were red and swollen, with urticaria on the labia. Although skin tests showed a positive reaction in two of three women tested, no sperm agglutination antibody was detected. Benadryl was effective in preventing the development of vulvovaginal reactions completely in one woman and partially in two others.

Adult↗