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Biomedical subjects

J B Mahony

Publications and source records attributed to J B Mahony.

At least 55 records · Page 3Linked to original sources
PubMed1994

Diagnosis of Chlamydia trachomatis infections in men and women by testing first-void urine by ligase chain reaction.

From April to September 1993, 305 men and 447 women in Hamilton, Canada, consented to the collection of a urethral or cervical swab, respectively, for culture and 20 ml of first-void urine (FVU) for testing by the enzyme immunoassay Chlamydiazyme and by ligase chain reaction (LCR) in the form of a kit from Abbott Laboratories called LCx Chlamydia trachomatis. Evaluation of test performance with each specimen was calculated on the basis of an expanded "gold standard" of a patient found to be positive by culture or by a confirmed nonculture test. By using this expanded standard, the prevalence of infection was determined to be 6% (27/447) for the women and 18.4% (56/305) for the men. LCR testing of FVU in both studies was the most sensitive approach (96%). The performance of Chlamydiazyme was as follows: cervical swab, 78.3% sensitivity; female FVU, 37% sensitivity; and male FVU, 67.9% sensitivity. Culture was the least sensitive approach to diagnosis: female cervix, 55.6%; and male urethra, 37.5%. LCR testing of FVU from men or women diagnosed the greatest number of genitourinary tract infections with no false positives.

Bacteriuria↗
PubMed1994

Leukocyte esterase urine strips for the screening of men with urethritis--use in developing countries.

BACKGROUND AND OBJECTIVES: The leukocyte esterase (LE) strip is a useful tool for the screening of men with urethritis. In developing countries, where laboratory facilities are limited, and sexually transmitted diseases endemic, simple and inexpensive diagnostic tests which perform well, would be of great value. METHODS: Men presenting with urethritis to a referral clinic for sexually transmitted diseases in Nairobi, Kenya participated in this cohort analytical study. First-void urine was collected for LE dipstick testing as part of the diagnostic work-up. The results of the dipstick measurement were compared with the laboratory detection of Chlamydia trachomatis and Neisseria gonorrhoeae. RESULTS: Of 200 men with symptoms of urethritis, 33 (17%) had a pathogen detected from the urethra or the urine. Chlamydia was detected in urine by PCR in 22 (11%), and gonorrhoea was cultured from the urethra in 11 (6%). Esterase activity (trace or greater) had a sensitivity of 76%, a specificity of 80%, a positive predictive value of 42% and a negative predictive value of 94% for the presence of chlamydia or gonorrhoea. CONCLUSIONS: The use of the LE dipstick for the screening of men with symptomatic urethritis can improve diagnostic accuracy and reduce the amount of empiric antimicrobial therapy. The low detection rate of chlamydia in these men with a clinical diagnosis of nongonococcal urethritis needs further study.

Adult↗
PubMed1993

Comparison of plasmid- and chromosome-based polymerase chain reaction assays for detecting Chlamydia trachomatis nucleic acids.

Several laboratories have demonstrated that the polymerase chain reaction (PCR) is more sensitive than culture or enzyme immunoassay (EIA) for detecting Chlamydia trachomatis in genitourinary tract specimens when various DNA targets are used for amplification, including the cryptic plasmid, major outer membrane protein (MOMP), or rRNA genes. We compared the performances of five different PCR assays, including assays with two plasmid, two MOMP, and one rRNA targets, by amplifying serial dilutions of C. trachomatis DNA and testing genitourinary tract specimens. By using published procedures, two different plasmid primers had sensitivities of 0.1 fg for C. trachomatis plasmid DNA and 10 fg for total cellular DNA. The sensitivities of the assays with the two MOMP primers were 0.1 and 10 pg, and the sensitivity for the assay with the rRNA primers was 1 pg for cellular DNA. Both plasmid-based assays detected 38 of 38 confirmed Chlamydiazyme-positive specimens, whereas the assays with the MOMP and rRNA primers detected 36 of 38 and 29 of 38 confirmed Chlamydiazyme-positive specimens, respectively. Six of 18 Chlamydiazyme-negative specimens collected from individuals whose specimens were positive by culture or immunofluorescence were positive by both plasmid-based PCRs; 4 of these were positive by PCR with the MOMP primers and 3 were positive by PCR with the rRNA primers. The results obtained with both purified DNA and genitourinary tract specimens indicated that the plasmid-based PCRs are more sensitive than bacterial chromosome-based PCRs for detecting C. trachomatis.

Bacterial Outer Membrane Proteins↗
PubMed1992

Replication and cytopathology of human parvovirus B19 in human umbilical cord blood erythroid progenitor cells.

Human parvovirus B19 productively infected erythroid progenitor (EP) cells from umbilical cord blood, in vitro as shown by an increase of viral DNA in supernatant fluid assayed by dot blot hybridization and liquid scintillation counting. Progeny virus was released into the supernatant fluid of CD34+ EP cells which had been purified by immunomagnetic separation. This supernatant fluid was infectious for bone marrow cells. Erythroid bursts infected with virus showed characteristic cytopathic effect by electron microscopy consisting of cytoplasmic vacuolization, marginated chromatin, and nuclear inclusions of lattice or crystalline arrays. Cultures of umbilical cord blood EP cells may be useful for the propagation of parvovirus B19 serological testing reagents and the study of virus-host cell interactions.

Base Sequence↗
PubMed1992

Chlamydia trachomatis confirmatory testing of PCR-positive genitourinary specimens using a second set of plasmid primers.

A plasmid-based PCR for the detection of Chlamydia trachomatis was evaluated with a confirmatory PCR employing a second set of plasmid primers. A total of 258 genitourinary specimens including 134 female endocervical and urethral specimens and 124 male urethral specimens were tested by culture, blocked EIA and PCR. Fifty-four specimens were positive by culture, 50 were positive by EIA and 71 were positive by PCR. Fourteen specimens that were PCR-positive but culture- and EIA-negative were confirmed positive by the confirmatory PCR. Two of the 187 specimens which were negative by culture and EIA were positive by PCR but failed to confirm with the second set of primers. Using an expanded gold standard of culture, blocked EIA and confirmed PCR, the overall sensitivities for culture, blocked EIA and confirmed PCR were 76.0% (54/71), 70.4% (50/71) and 100% (71/71) and the specificities were 100% (187/187), 100% (187/187), respectively. These results demonstrated that a confirmatory PCR was useful for sorting out discordant specimens and establishing the true specificity of PCR. Furthermore, these results demonstrate that PCR is more sensitive than culture and EIA and suggest that a confirmed PCR test should be included in the gold standard for the evaluation of new tests for diagnosing Chlamydia trachomatis infections.

Chlamydia Infections↗
PubMed1992

Chlamydial antibodies in children with lower respiratory disease.

Forty-nine of 255 (19.2%) Argentinean children between the ages of 1 and 18 months without evidence of viral or bacterial infections, but with clinical and radiologic evidence of acute lower respiratory distress, had serologic evidence of recent Chlamydia trachomatis infection by the demonstration of specific IgM, seroconversion or 4-fold rise in titer or elevated titers by enzyme immunoassay and the microimmunofluorescence test. Recent C. trachomatis infection was detected in 28 of 166 (16.9%) of children with bronchiolitis and 18 of 89 (20.2%) with pneumonia. Three additional children with bronchiolitis had Chlamydia pneumoniae-specific antibody. There was a significantly higher prevalence of C. trachomatis infection in children living in La Plata city orphanage (26 of 74, 35.1%) than in those attending 2 pediatric hospitals in Buenos Aires (23 of 181, 12.7%) (P less than 0.001). C. trachomatis infection was detected in all age groups up to 18 months. Thirty of 49 infections were in children older than 3 months of age and 16 were in children older than 6 months. These results suggest that C. trachomatis infection may be associated with bronchiolitis and pneumonia in children between the ages of 1 and 18 months of age in Argentina and that a proportion may be horizontally transmitted.

Antibodies, Bacterial↗
PubMed1992

Confirmatory polymerase chain reaction testing for Chlamydia trachomatis in first-void urine from asymptomatic and symptomatic men.

First-void urine specimens from 683 men (592 without symptoms) were tested for Chlamydia trachomatis by a polymerase chain reaction (PCR) with KL1 and KL2 plasmid primers and by a Chlamydiazyme enzyme immunoassay (EIA). Thirty-seven specimens were confirmed to be positive by using the EIA blocking reagent and a second set of plasmid primers (T1 and T2). By comparing unconfirmed PCR results (KL1 and KL2 primers only) with the blocked Chlamydiazyme EIA results, the sensitivity and specificity of PCR were 100% (37 of 37 specimens) and 99.5% (643 of 646 specimens), respectively. Three additional specimens were negative by EIA but positive by PCR and were confirmed to be positive with primers T1 and T2. Two of the three specimens were from men with symptoms. The confirmatory PCR assay performed equally well in detecting positive specimens from symptomatic (31 of 31) and asymptomatic (9 of 9) men. Comparison of confirmatory testing of first-void urine specimens by PCR and EIA showed that PCR was 100% sensitive (40 of 40 specimens) and that the EIA was 92.5% sensitive (37 of 40 specimens) but that the assays were equally specific (100%).

Chlamydia Infections↗
PubMed1992

Ciliary function, cell viability, and in vitro effect of ribavirin on nasal epithelial cells in acute rhinorrhea.

Nasal epithelial (NE) cells were collected from the nasopharynx of 25 individuals with symptomatic colds and 27 healthy volunteers (controls), and ciliary beat frequency (CBF) was assessed by microscopy employing video motion analysis techniques. Baseline CBF was statistically significantly elevated in the group with colds compared to the control group (14.6 +/- 1.5 Hz [mean +/- SD] vs 13.8 +/- 0.9 Hz; p = 0.02). After four days of incubation in culture, there was a significant decrease in the CBF in both groups, with a change from baseline of 1.9 Hz for the cold group, compared to 1.0 Hz for the control group (p = 0.0001). The in vitro addition of ribavirin at 500 micrograms/ml to NE cells from individuals with colds preserved the viability of the cells and maintained the CBF at baseline values. Twenty-four (96 percent) of 25 ribavirin-treated specimens from the cold group survived for four days in culture, compared with 17 (68 percent) of 25 untreated cold specimens. In addition, the ribavirin-treated cells had a mean CBF of 14.2 +/- 1.3 Hz, compared with 12.7 +/- 1.9 Hz for the untreated cell samples (p = 0.0005). Ribavirin had no effect on NE cells from the control group. These results suggest that ribavirin in a concentration of 500 micrograms/ml may have some benefit in the treatment of acute rhinorrhea.

Acute Disease↗
PubMed1992

The effects of equine rhinovirus, influenza virus and herpesvirus infection on tracheal clearance rate in horses.

The response of horses exposed to three common respiratory viruses was studied by measuring tracheal mucociliary clearance rates in the trachea. Tracheal clearance rates (TCR) were determined before, during illness and following recovery in horses exposed to equine rhinovirus (ERhV-2), equine influenza virus (EIV) and equine herpesvirus (EHV-4) by means of lateral scintigraphs made following an injection of technetium-99m sulphide colloid into the tracheal lumen. In six horses exposed to ERhV-2, TCR remained within normal limits. Exposure to EIV resulted in reduced TCR in six of seven horses, with TCR remaining below the 95% confidence limits of normal values for each horse for up to 32 days despite the resolution of clinical signs. Moderate changes were observed in six horses exposed to EHV-4, but significant reductions in TCR were evident in three animals. Measurement of TCR was a useful, minimally-invasive technique which demonstrated that respiratory viruses may cause persistent changes in TCR, even though clinical signs are not evident.

Animals↗
PubMed1992

Effectiveness and efficiency of selective vs universal screening for chlamydial infection in sexually active young women.

BACKGROUND: Since chlamydial cervicitis is not associated with specific complaints, screening asymptomatic women is an important initiative to prevent pelvic inflammatory disease and its sequelae. Compared with universal screening, selective screening is less costly but less effective so the cost savings vs the consequences of missing infected women need to be weighed carefully. METHODS: In two family planning clinics, 1002 women were surveyed for chlamydial infection (prevalence, 7%) and its predictors to determine whether universal or selective screening is the most efficient strategy. Two rules for the selection of patients were determined by logistic regression modeling and their relative efficiencies were compared by incremental cost-effectiveness and sensitivity analysis. The validity of the screening rules was tested in 191 students attending a university health clinic. RESULTS: If those with cervical friability, suspicious discharge, urinary frequency, or intermenstrual bleeding had been tested, 55.3% of all women would have been screened and 83.3% of all cases would have been detected. If those reporting a new sex partner in the preceding year had also been tested, 75.4% would have been screened, identifying 93.3% of all cases. The predictive power and practicality of the selection rules were validated in the university health clinic sample. Sensitivity analyses showed selective screening using cervical enzyme immunoassay with blocking confirmation was efficient if the prevalence of chlamydial infection was 16% or less, 11% or less, or 5% or less depending on whether base analyses, overestimated costs, or worst performance scenarios, respectively, were used. CONCLUSIONS: Selective screening based on four or five predictors and confirmed cervical enzyme immunoassay is an effective and efficient strategy in low prevalence settings.

Adult↗
PubMed1991

Analysis of a pregnancy-screening and neonatal-immunization program for hepatitis B in Hamilton, Ontario, Canada, 1977-1988.

During the 12 years from January, 1977, to December, 1988, the Hamilton Centre of the Canadian Red Cross Society (CRCS) Blood Transfusion Service screened 98,712 pregnant patients for hepatitis B surface antigen (HBsAg) and identified 120 positives (0.12%). The number of positives ranged from six to 16 per year. We were able to trace and enroll 65 mothers (54%) and 96 of their children in the follow-up study. The majority of the women were between 20 and 30 years of age (95.4%) and married (86%), and about one-half were employed outside the home. Sixty-five percent were white and 34% Asian, and 20 countries were listed as their places of origin. Hepatitis B immune globulin (HBIG) was available for neonatal immunization since 1977 and combined with vaccine since 1982. Of the 96 candidates for HBIG, 60 (63%) received HBIG within 24 hr, one after 3 months, four unknown, and 31 did not receive it. Of the 56 candidates for vaccination from 1982 to 1989, 26 (46%) received three doses, seven had two doses, eight had one dose, one was unknown, and 14 had none. HBsAg tests were performed on 69 children (71.8%) and anti-HBs on 61 (63.5%). Four of the children are HBsAg positive, 31 have anti-HBs, and 31 have no detectable antibodies. All four HBsAg positives had not received vaccine, and only one had received HBIG. Of the children positive for hepatitis B surface antibodies, five had received no immunization and therefore had been subclinically infected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The diagnosis of acute viral hepatitis A or B by microparticle enzyme immunoassay.

The traditional approach to the diagnosis of viral hepatitis has been to collect a serum sample and to test it for the presence of hepatitis B surface antigen (HBsAg), IgM to the core of HBV (anti-HBc IgM) and IgM to HAV (anti-HAV IgM) by solid phase radio- or enzyme immunoassays. Microparticle enzyme immunoassay technology (IMx-Abbott Laboratories) has been introduced as an automated carousel system for the detection of these markers. A side-by-side, blinded comparison of IMx to current IA was performed for HBsAg on 659 specimens submitted from March to July 1990, of which 72 (10.8%) were positive by AUSRIA (Abbott RIA for HBsAg) and 2 of these were discordant in IMx. Both were near the cutoff and by confirmatory testing one was positive and the other negative. Forty three percent (25/58) of frozen stored sera tested for anti-HBc IgM, by IMx, were positive by EIA (Corzyme M). One specimen near the cutoff was negative by EIA but weakly positive by IMx. Anti-HAV IgM was found in 21.8% (46/211) of sera with 100% correlation by IMx. Thus IMx had the following percent sensitivies and specificities: HBsAg; 98.6, 99.9; anti-HBc IgM; 100, 99.9; anti-HAV IgM; 100, 100. The test set-up times for the 3 markers in the IMx were similar to the RIA and EIA. The turnover time was 45 min for a full IMx carousel compared to: AUSRIA-short incubation (4 h), or long incubation (14 h); Corzyme M-short (4.75 h) or long (20 h); anti-HAV IgM (23 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Automation↗
PubMed1991

Comparison of cervical, urethral, and urine specimens for the detection of Chlamydia trachomatis in women.

Cervical, urethral, and first void urine (FVU) specimens from 937 women were tested for Chlamydia trachomatis by culture or EIA to determine the most sensitive combination of tests and specimens. For cervical and urethral specimens the prevalence of infection by culture or confirmed EIA was 7.2% (67/937) at either site, 6.8% (64/937) at the cervix, and 4.3% (40/937) at the urethra. Of 67 specimens, 37 (55.2%) yielded a positive test from both the cervical and urethral swabs. Three (4.5%) of the 67 infections were only at the urethra and none were only in FVU. Only 37.3% (25/67) of all positive women had a positive FVU. The most sensitive combination was cervical swab culture and EIA, which detected 95.5% (64/67) of the infections, a substantial increase over culture only (76.1%) or EIA of the cervical swab (79.1%). The testing of urethral and FVU specimens apparently offers only minimal advantage over testing of cervical specimens only for chlamydia.

Adolescent↗
PubMed1991

Nasal polyposis: in search of a viral etiology using DNA hybridization.

The etiology of nasal polyps is unknown. Numerous theories have been proposed, with allergic and infectious causes predominant. A viral theory was postulated almost 40 years ago. In a pilot project, we studied 15 subjects comprising six controls and nine patients with nasal polyps. No known viruses were cultured from the nasal polyp tissue or nasal mucosal biopsies from the control subjects. DNA Hybridization for Epstein-Barr Virus, Herpes simplex virus, adenovirus type V, and Chlamydia trachomatis were also negative for all tissue studied. The use of molecular biological techniques is not widespread in otolaryngology and this is the first report, to the best of our knowledge, of the application of these techniques for the investigation of the viral etiology of nasal polyps.

Adult↗
PubMed1990

A new immune complex dot assay for detection of rotavirus antigen in faeces.

A new immune complex dot assay (ICDA) using immune gold/silver staining is described for the sensitive and rapid detection of rotavirus in cell culture and stool specimens. The method involves spotting preformed antigen-antibody complexes onto nitrocellulose paper, followed by incubation with colloidal gold-labelled secondary antibody and silver enhancement. ICDA was sensitive and specific and detected rotavirus antigens over a wide range of concentrations. It was more sensitive than a conventional immunodot assay (CIDA) and two commercial enzyme immunoassays (EIA) based on testing serial dilutions of a positive stool specimen. Of 26 stool specimens tested ICDA detected rotavirus antigen in 17; 14 were positive by Pathfinder Rotavirus EIA, 16 by Testpack Rotavirus EIA, and direct electron microscopy (DEM) detected only 12. The ICDA offers improved sensitivity over commercial EIAs and DEM.

Antigen-Antibody Complex↗
PubMed1990

Sensitive solid-phase immune electron microscopy double-antibody technique with gold-immunoglobulin G complexes for detecting rotavirus in cell culture and feces.

A new solid-phase immune electron microscopy double-antibody colloidal-gold technique (SPIEMDAGT) was developed and compared with direct electron microscopy, direct immune electron microscopy, and enzyme immunoassay for detecting rotavirus. Guinea pig and rabbit antirotavirus antisera were used as capture and detector antibodies, respectively, and goat anti-rabbit immunoglobulin G-gold complexes were employed as a label. Animal rotavirus in cell culture media and human virus in stool specimens were detected by this method. On average, SPIEMDAGT detected 800 times more virus particles than direct electron microscopy and 45 times more particles than direct immune electron microscopy and yielded 20% more positives than enzyme immunoassay. SPIEMDAGT could detect not only viral antigen associated with morphologically recognizable particles but also antigen present when whole virus particles were not visible.

Antibodies, Viral↗