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Biomedical subjects

J Silva

Publications and source records attributed to J Silva.

At least 235 records · Page 13Linked to original sources
PubMed1981

Isolation of Clostridium difficile from the environment and contacts of patients with antibiotic-associated colitis.

Clostridium difficile is the most important cause of antibiotic-associated colitis, but its epidemiology remains unknown. Using a selective medium for the isolation of C. difficile, cultures were obtained from the environment and contacts of hospitalized patients carrying C. difficile in their stools. In areas where carriers had diarrhea, 85 (9.3%) of 910 cultures of floors and other surfaces, especially those subject to fecal contamination, were positive. In areas where there were no known carriers, only 13 (2.6%) of 497 cultures of similar sites were positive (P less than 0.005). C difficile was isolated from hands and stools of asymptomatic hospital personnel, from sewage and soil, and from the home of a patient. Environmental isolates were toxigenic. C. difficile inoculated onto a floor persisted there for five months. Further studies are needed to document how often floor persisted there for five months. Further studies are needed to document how often C. difficile shed by patients with antibiotic-associated colitis is acquired by other persons and whether isolation precautions are capable of limiting the organism's spread.

Anti-Bacterial Agents↗
PubMed1981

Studies on the epidemiology of colitis due to Clostridium difficile in hamsters.

Hamsters treated with vancomycin developed enterocolitis significantly more often in a conventional animal room than in a room designed to prevent cross-infection with Clostridium difficile. In the conventional room C. difficile was isolated from cages, food racks, floors, buckets, the hands of caretakers, and the stools of animals with enterocolitis but not from untreated hamsters, air, or food from freshly opened bags. C. difficile was not isolated from environmental sources in the clean room. It was not possible to determine which of the sources of the organism was most important in its spread. Cross-infection with C. difficile may be important in the pathogenesis of antibiotic-associated enterocolitis in hamster colonies.

Animals↗
PubMed1981

Evaluation of eight cephalosporins in hamster colitis model.

Eight commonly used cephalosporins were evaluated in the hamster colitis mode. They were all found to cause hemorrhagic cecitis and death within 10 days of being given as subcutaneous or oral challenges. Necropsy findings were indistinguishable from clindamycin-induced cecitis. Bacteria-free cecal filtrate obtained from hamsters dying of cephalosporin-induced cecitis contained toxin similar or identical to hat produced by Clostridium difficile isolated from the cecum of a hamster. Daily oral administration of poorly absorbed cephalosporins protected hamsters from clindamycin-induced cecitis and death as long as the cephalosporins were continued. The absorbable cephalosporins were ineffective in protecting hamsters from clindamycin-induced cecitis. This difference probably relates to the lower concentrations of absorbable cephalosporins maintained in the ceca of the hamsters. The possible correlation of these findings to human cases of cephalosporin-induced pseudomembranous colitis is discussed.

Animals↗
PubMed1981

Leiomyoma of the female urethra and bladder neck.

A case of female urethral leiomyoma is presented. Due to its site of origin, at the bladder neck, the clinical picture resembled that of male prostatic median lobe enlargement. TUR was performed successfully and the authors feel that this should be considered the procedure of choice for leiomyomas arising in the proximal female urethra.

Cystitis↗
PubMed1981

Inhibitors of monocyte responses to chemotaxins are present in human cancerous effusions and react with monoclonal antibodies to the P15(E) structural protein of retroviruses.

Individuals with cancer have previously been shown to have abnormal chemotactic responsiveness. Surgical removal of the tumor often resulted in normalization of monocyte function, which suggests that human neoplasms might inhibit monocyte chemotaxis by release of soluble mediators. We therefore examined the effects of cancerous effusions on monocyte polarization, i.e., the rapid change in monocyte morphology from round to a triangular "motile" configuration in response to chemoattractants. All 17 malignant effusions, representing 15 tumor types, inhibited monocyte polarization induced by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine by 45-89% (mean 55.9 +/- 12.7%, P less than 0.01) in blinded assays. None of 17 benign effusions signigicantly inhibited polarization (0-15%, mean 6.2 +/- 4.2%). Dilutions of cancerous effusions as low as 1:200 produced inhibition that was time, temperature, and dose dependent . Monocyte polarization induced by activated serum or by chemotactic lymphokine was also blocked by cancerous effusions. The inhibitory activity affected the monocyte directly, and did not destroy the chemoattractant or block the polarization of granulocytes to chemotactic factors. High pressure liquid chromatography of five cancerous fluids revealed three peaks of inhibitory activity: greater than or equal to 200,000, 46,000 +/- 13,000, and 21,000 +/- 3,000 daltons. Fractionation of noncancerous effusions revealed only small amounts of the highest molecular weight inhibitory activity. The inhibitory activity in cancerous effusion was heat stable (56 degrees C, 30 min), trypsin sensitive, and could be absorbed by three different monoclonal antibodies reactive to P15(E), a structural component of type C retroviruses. In contrast, six monoclonal antibodies with other specificities had no effect on the inhibitors of polarization. This study demonstrates that human cancerous effusions contain novel proteins that are potent inhibitors of monocyte function and that are recognized by antibodies reactive to the P15(E) component of retroviruses. By producing such factors, tumor cells may subvert monocyte-mediated surveillance.

Adult↗
PubMed1980

Studies on the epidemiology of antibiotic-associated Clostridium difficile colitis.

Vancomycin protects hamsters from the development of Clostridium difficile colitis after treatment with clindamycin, and vancomycin is useful in treatment of humans with the disease. Relapses have occurred in both hamsters and humans when vancomycin is discontinued. Vancomycin appears to enhance susceptibility to colonization with C. difficile by eliminating competing intestinal organisms. The nature of these organisms is not known, but various tools are now available to aid in identifying them. Cancer chemotherapeutic agents should be added to the list of factors such as surgery and antibiotics that may predispose to emergence of C. difficile. The number of organisms required for colonization of antibiotic-treated hamsters is low and cross-infection seems to play a role in the disease in hamster colonies. The organism can be detected on surfaces in rooms of patients with the disease, and on the hands of personnel caring for them. Outbreaks of the disease have been recognized. Our results suggest isolation precautions should be used to prevent spread of the organism from patients with the disease to others being treated with antibiotics.

Animals↗
PubMed1980

In vitro defects of phagocyte chemotaxis during pregnancy.

Pregnant women have an increased risk for some infections, particularly during the last trimester. Phagocytic emigration from the circulation into tissues is an important aspect of the initial immune response. Therefore, circulating phagocytes of 42 pregnant and 15 postpartum patients were studied in vitro for random and chemotactic (or directional) migration through membrane filters (Millipore Corp., Bedford, Mass.). Random migration of phagocytes from all 42 pregnant patients studied in each trimester was within normal limits. Chemotactic migration of 25 patients who were between 6 and 33 weeks of pregnancy was also similar to values obtained with control leukocytes (20 nonpregnant, normal females. However, phagocytes of 17 other women studied between week 34 of pregnancy and term showed marked depressions in chemotaxis (P less than 0.001 from control values). During labor and within 3 days of delivery, chemotactic migration increased to supranormal levels in 14 of 15 women studied. Sera from six pregnant patients with proven chemotactic defects did not reduce migration when incubated with normal phagocytes. These chemotactic defects appear to be intrinsic and may be important in predisposing to infections during late pregnancy.

Blood↗
PubMed1980

Mucosal damage mediated by clostridial toxin in experimental clindamycin-associated colitis.

A toxin produced by Clostridium difficile has been implicated in the pathogenesis of antibiotic-associated colitis in humans and experimental animals. This study was undertaken in order to define the sequential evolution of caecal mucosal lesions in the hamster and to relate those lesions directly to the clostridial toxin. Sterile filtrates from a culture of C. difficile and from caecal contents of clindamycin-treated hamsters were studied with respect to their effects on the caecal mucosa and on cultured cell monolayers. The toxic filtrates both produced cellular swelling in vitro, and appeared to have a similar cytotoxic effect on caecal epithelial cells in vivo. Cellular damage was followed by extensive epithelial desquamation and the evolution of an acute pseudomembranous typhlitis. The pathogenetic sequence produced by the filtrates was identical with that previously described after direct clindamycin treatment. These findings demonstrate that intraluminal clostridial toxin can mediate development of the characteristic antibiotic-associated mucosal lesions.

Animals↗
PubMed1980

A syndrome of multiple immune autoreactivity. A breakdown in immune regulation.

The clinical findings of pemphigus vulgaris, rheumatoid arthritis, and Sjögren's syndrome were found in a patient displaying immunological abnormalities found in pemphigus vulgaris, systemic lupus erythematosus, rheumatoid arthritis, and Hashimoto's thyroiditis. Some of the antigen-antibody systems detected in this case were further identified. Our patient may be an example of severe failure in immune regulation.

Antibodies, Antinuclear↗
PubMed1980

Suppression of immune response in mice by navy bean lectin.

A cluster of cases of Hodgkin's disease was observed in a small town which contained a large navy bean elevator. In previous investigations a lectin was isolated from the navy beans and lymphocytes from town residents were shown to be sensitized to this lectin. Mice were exposed to 15 weekly injections of navy bean lectin. Splenic lymphocytes from injected mice incorporated greater amounts of thymidine than did controls when incubated with the lectin. Cell-mediated immunity as measured by a Concanavalin A dose-response curve was significantly suppressed (p < 0.01) in the injected mice. Long term studies are needed to see if the decreased Concanavalin A response in the mice chronically stimulated with navy bean lectin will predispose to lymphoreticular malignancies.

Animals↗
PubMed1979

Cohort study of Michigan residents exposed to polybrominated biphenyls: epidemiologic and immunologic findings.

Polybrominated biphenyls (PBB) were dispersed widely in Michigan by a 1973 shipping accident in which PBB was introduced into cattle feed. Human exposure resulted principally from ingestion of contaminated dairy food products. To determine whether PBB exposure has or will cause acute or chronic illness, a prospective cohort study of 4545 persons has been undertaken. Three exposure groups were sought; all persons living on PBB-quarantined farms; persons who had received food directly from such farms; workers (and their families) engaged in PBB manufacture. Enrollment rates were 95.6, 95.1 and 78.0%. Also enrolled were 725 persons with low-level PBB exposure. All were queried concerning 17 symptoms and conditions related possibly to PBB. Venous blood was drawn on 3639 and analyzed for PBB by gas chromatography. Mean serum PBB levels were 26.9 ppb in quarantined farm families, 17.1 in recipients, 43.0 ppb in workers, and 3.4 ppb in the low exposure groups. No associations were found between serum PBB levels and symptom prevalence rates. To evaluate peripheral lymphocyte function, T and B cell quantitation and in vitro responses to 3 nonspecific mitogens were studied in 34 persons with highest PBB levels (mean, 787 ppb), and in 56 with low values (mean, 2.8 ppb). No statistically significant differences in lymphocyte number or function were noted.

Adolescent↗
PubMed1979

Herpetic whitlow: herpetic infections of the digits.

Ten cases of herpes simplex infections of a digit were observed during a 3 year period. The diagnosis was confirmed in seven cases by culture or tests of serum antibodies. In three cases the clinical characteristics were sufficient to suggest the diagnosis. Medical and dental personnel are particularly prone to develop this affliction; their occupations are a frequent clue to the diagnosis. Nonsurgical treatment of this self-limited entity is recommended.

Adult↗