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Biomedical subjects

S Selwyn

Publications and source records attributed to S Selwyn.

At least 19 recordsLinked to original sources
PubMed1989

Early diagnosis of cytomegalovirus infection in renal transplant and dialysis patients by DNA-DNA hybridisation assay.

One hundred forty-eight urine specimens were collected from 47 renal transplant and dialysis patients and screened for the detection of cytomegalovirus (CMV). Diagnosis of CMV infection was suggested in 17 out of 47 patients (36.2%) by more than one of the five methods used. DNA hybridisation assay (DNA HA) using 32P-labelled probe detected CMV DNA in 15 (31.9%) of 47 patients, whereas virus isolation on conventional tube cell cultures (CTC), immunofluorescence incorporating monoclonal antibodies on centrifugation vial cultures (IF), complement fixation test (CFT), and electron microscopy (EM) yielded positive results in only nine (19.2%), 12 (25.2%), 11 (23.4%), and one (2.1%) of 47 patients, respectively. The significance of these results obtained by DNA HA lies not only in the apparent increase in number of patients diagnosed, but also in both early and rapid detection of CMV DNA. More importantly, the DNA HA is highly specific in that it correlates accurately with clinical and laboratory data characteristic of CMV disease. In respect of clinically manifest CMV disease, the specificity of DNA HA, CTC, IF, CFT, and EM was 87.5, 43.7, 56.3, 43.7, and 6.3%, respectively. These advantages of DNA HA make it the test of choice for early diagnosis of CMV infections in immunosuppressed patients.

Complement Fixation Tests↗
PubMed1989

Beta-lactamase stability and antibacterial activity of cefpirome alone and in combination with other antibiotics.

The antibacterial activity of cefpirome (HR810), a new cephalosporin, was compared with that of other "third-generation" cephalosporins, as well as cefuroxime, piperacillin and gentamicin. Cefpirome was the most active beta-lactam antibiotic against Gram-negative bacteria. The MIC90 for Enterobacteriaceae was always less than 0.5 ml/l except for Enterobacter species. The MIC90 against Pseudomonas species was 2 mg/l, which was equal to that of ceftazidime and gentamicin. Cefpirome was also more active than the other beta-lactam antibiotics against Staphylococcus aureus. A relatively high frequency of synergy was observed when cefpirome was combined with aminoglycosides against both Gram-positive and Gram-negative bacteria. No antagonism was detected. This antibiotic was very stable to both plasmid- and chromosomally-mediated beta-lactamases. It was more resistant to Enterobacter cloacae P99 enzyme than ceftazidime, cefotaxime and cefotetan. Its stability to the Klebsiella K1 beta-lactamase was more than that of cefotaxime and ceftriaxone but slightly less than that of ceftazidime and latamoxef. MBC90 values for cefpirome were generally less than twice the corresponding MIC values.

Cephalosporins↗
PubMed1988

New and sensitive standard cell culture technique for the detection of cytomegalovirus in clinical specimens.

Conventional tube cell culture has been recognised as the most sensitive technique available for human cytomegalovirus (HCMV) detection. Low-speed centrifugation of specimen inocula onto cell culture monolayers has been shown to increase the efficiency of infection with the AD 169 strain of HCMV. Therefore a centrifugal force of 900g for 1 hour at 37 degrees C was used to enhance the detection of HCMV cytopathic effect (CPE) in shell vials that contained circular coverslips with a monolayer of human embryonic lung (HEL) fibroblasts. Of 195 specimens, HCMV CPE was detected in 18 specimens (9.02%) on shell vial culture assay, whereas conventional tube cell culture was positive in only 13 specimens (6.6%). The shell vial culture assay was significantly more sensitive (P less than 0.05). Furthermore the development of the cytopathic effect on shell vial culture assay was significantly earlier (P less than 0.01) and more extensive. Urine samples were sonicated and the results obtained with immunofluorescence using human immune serum demonstrated that sonication increased both the intensity of fluorescence and number of fluorescent foci of HCMV-infected cells and also decreased the non-specific fluorescence of the background.

Cells, Cultured↗
PubMed1988

Detection of human cytomegalovirus by slot-blot hybridisation assay employing oligo-primed 32P-labelled probe.

A 32P-labelled Hind III-0 DNA fragment (nine Kilobases; Kb) from human cytomegalovirus AD-169 (HCMV) was used in slot-blot hybridisation assay for the detection of HCMV in clinical samples. The results obtained with DNA hybridisation assay (DNA HA) were compared with virus isolation using conventional tube cell culture (CTC) and centrifugation vial culture (CVC), immunofluorescence (IF), and complement fixation test (CFT). Of 15 CTC-positive samples, 13 were positive with DNA HA (sensitivity 86.7%). Also, 14 additional samples were DNA HA-positive but CTC-negative. CVC and/or IF confirmed the diagnosis in nine of 14; the remaining five samples were from three patients who showed fourfold rising antibody titre by CFT. Although DNA HA using 32P-labelled probes is relatively cumbersome and expensive, it is a valuable test for quantitation of viral shedding in patients with HCMV infections who may benefit from antiviral therapy.

Cells, Cultured↗
PubMed1988

Combined use of sonication and monoclonal antibodies for the detection of early and late cytomegalovirus antigens in centrifugation cultures.

A total of 157 clinical specimens was inoculated into shell vials and conventional tube cell cultures containing confluent monolayers of human embryonic lung fibroblasts (HELF). Of 31 clinical cytomegalovirus (CMV) isolates, 30 specimens (96.8%) were positive by the immunofluorescence method on centrifugation vial cultures (CVC-IF), whereas the cytopathic effects (CPE) of CMV were detected in only 14 specimens (45.2%) in conventional tube cell cultures (CCC), P less than 0.001 and in 22 specimens (70.9%) in centrifugation vial cultures (CVC-P), P less than 0.1. Significantly more fluorescent foci were detected in centrifugation cultures inoculated with sonicated urine samples (P less than 0.001). CVC-P is more sensitive than CCC for the diagnosis of CMV (P less than 0.05), and a highly significant difference was observed when we compared the mean day to initial detection of CPE (P less than 0.001). For optimal detection of CMV, both CVC-IF and CVC-P should be used for the laboratory diagnosis of this virus infection.

Antibodies, Monoclonal↗
PubMed1986

Comparative in vitro studies on cefotaxime and desacetylcefotaxime.

After its parenteral administration in man, cefotaxime is partially metabolized to the desacetyl derivative (24-30% appearing in urine as desacetyl form). A detailed study was therefore carried out in vitro to compare the antibacterial activity against a wide range of clinical isolates and also the beta-lactamase stability of cefotaxime and desacetylcefotaxime, as well as other third-generation cephalosporins. The investigations of bacteriostatic and bactericidal activity were, in addition, extended to representative ureido-penicillins, cefuroxime, aminoglycosides and second-generation quinolones. Although cefotaxime was generally 4 to 8 times more active than its desacetyl derivative, smaller differences were observed against some strains of Enterobacteriaceae, Haemophilus influenzae and gonococci. A similar pattern was seen in relation to beta-lactamase stability, the parent antibiotic being generally more resistant to hydrolysis. Cefotaxime was, overall, the most active of the beta-lactam agents, except against pseudomonads, staphylococci and enterococci. In general, the antibiotic possessed comparable in-vitro efficacy to that of gentamicin, netilmicin and ciprofloxacin. Studies of combinations of cefotaxime and desacetylcefotaxime were carried out by the checkerboard method on solid media and also using a killing curve system in liquid media. A useful degree of synergy was observed against the majority of test organisms. This valuable effect could enhance the activity of cefotaxime in vivo, despite partial desacetylation.

Cefotaxime↗