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Biomedical subjects

W A Black

Publications and source records attributed to W A Black.

At least 19 recordsLinked to original sources
PubMed1995

Patient selection: indications and contraindications.

Patient selection is critical to the success of PLDD. In general, the herniation must have continuity with the parent disc; rupture of the annulus is not a contraindication. Several other orthopedic conditions constitute absolute or relative contraindications. All patients must be individualized. Our criteria for inclusion is undergoing continuing change. What is unacceptable now may, with modifications, become acceptable in the future. It is important not to adopt a fixed position at this early stage of PLDD.

Contraindications↗
PubMed1995

A neurosurgical perspective on PLDD.

This paper discusses the evolution of PLDD and its risks and complications, and points out some advantages and disadvantages. It presents data from a clinical study of 81 patients in which three technologies--automated percutaneous discectomy, KTP, and Nd:YAG laser instruments--were used. The study concludes that PLDD is safe and cost-effective. If the patients are properly chosen PLDD can be a good choice for treatment of herniated lumbar discs.

Diskectomy, Percutaneous↗
PubMed1994

Pulmonary penicillosis marneffei: report of the first imported case in Canada.

A 57-year-old female, born in Laos and who had lived in Thailand prior to immigrating to Canada in 1989, was seen by her physician with a chief complaint of cough and dyspnea. Her chest X-ray showed bilateral pulmonary air fluid levels. A fungus, with a diffusible red pigment, tentatively identified as Penicillium marneffei, was isolated from the patient's bronchial washings and sputum specimens. At 37 degrees C, the fungus converted to a yeast form when cultured on brain heart infusion agar. Microscopic examination of this culture revealed yeast cells that reproduced by fission. The identity of the patient's isolate was confirmed as P. marneffei with an exoantigen test. The patient's serum demonstrated specific antibodies to P. marneffei antigen. Treatment with amphotericin B and ketoconazole resulted in clinical improvement, clearing of chest X-rays and conversion to sero-negativity. Our case is the first recorded diagnosis of imported penicillosis marneffei in Canada. The minimal inhibitory concentrations recorded for the patient's isolate to fluconazole, 5-fluorocytosine, itraconazole and miconazole were 12.5, 0.39, < 0.195 and < 0.195 micrograms/ml, respectively.

Amphotericin B↗
PubMed1994

Mutations in the catalase-peroxidase gene from isoniazid-resistant Mycobacterium tuberculosis isolates.

Isoniazid resistance in Mycobacterium tuberculosis has been associated with total deletion of the katG gene, which codes for catalase-peroxidase production. To determine whether this is a common mechanism of drug resistance, 9 isolates of isoniazid-resistant and 1 of isoniazid-sensitive M. tuberculosis were analyzed by polymerase chain reaction amplification of a 237-bp sequence of the katG gene. Amplification was observed in the isoniazid-sensitive isolate and in 8 resistant isolates; in only 1 isoniazid-resistant isolate was there no amplification of the expected band, suggesting gene deletion. DNA sequencing showed that 8 of the 9 isolates had point mutations, deletions, or insertions of 1-3 bases. Evidence corroborating the presence of mutations in the katG gene was obtained by single-strand conformation polymorphism analysis in these 8 isolates. Thus, mutations as well as insertions and deletions in the katG gene can account for inactive catalase peroxidase, leading to isoniazid resistance; gene deletion occurs only infrequently, in approximately 11% of cases.

Bacterial Proteins↗
PubMed1993

Intrathoracic paediatric tuberculosis: a report of 202 cases.

Until recently paediatric tuberculosis rates were in decline in developed countries, but more recently there has been a significant change in these trends. Tuberculosis in British Columbia (BC) is centralized and all paediatric cases diagnosed between 1979 and 1988 were reviewed. There were 252 notifications during the study period but 50 cases were excluded (31 extrapulmonary cases, 11 with missing records and 8 because of incorrect diagnoses). There were 109 (54%) female patients. The age range was 4 months-15 years (6.4 +/- 4.1 years). 52% were 5 years old or less. 75 (37.1%) were aboriginal Canadians, 61 (30.2%) were Asian, 50 (24.8%) were Caucasian and 16 (8%) were included in miscellaneous or unknown groups. Primary pulmonary disease occurred in 197 (97.5%); the remaining 5 had post-primary disease. A history of close contact was elicited in 158 children (78.2%). All but 8 (4%) had a positive PPD response to 5TU. 40% of children had symptoms, the most frequent being cough (51%) and fever (28.4%). Mycobacteriology was carried out in 169 (83.7%) children. Bacteriologic confirmation was achieved in 45 patients (22.2%). Chest X-rays were reviewed in 186 cases. Lymphadenopathy occurred in 93.5%, with hilar (34%) and combined hilar-paratracheal (26%) being the commonest findings. The majority of patients were treated with isoniazid and rifampin, with a minority receiving streptomycin or pyrazinamide in the initial intensive phase. 14 (6.9%) children had adverse reactions to their drugs but these were rapidly reversed with the withdrawal of the responsible drug. Response to therapy was excellent and there were no deaths.

Adolescent↗
PubMed1992

Characterization of a DNA probe for detection of Mycobacterium tuberculosis complex in clinical samples by polymerase chain reaction.

We cloned and sequenced a DNA fragment from Mycobacterium tuberculosis for use in the identification of members of the M. tuberculosis complex. The DNA probe for culture confirmation had a sensitivity and a specificity of 100%. By using primers developed from this probe, the polymerase chain reaction detected 20 mycobacteria by ethidium bromide staining. This polymerase chain reaction system demonstrated 98% sensitivity and 100% specificity for detection of the M. tuberculosis complex in 200 sputum specimens.

Bacteriological Techniques↗
PubMed1990

Comparison of in vitro antimicrobial susceptibilities of Mycobacterium avium-M. intracellulare strains from patients with acquired immunodeficiency syndrome (AIDS), patients without AIDS, and animal sources.

Difloxacin, A-56620, cefazolin, cefotaxime, ceftizoxime, cephapirin, SK&F 88070, and spectinomycin were used to compare the in vitro susceptibilities of Mycobacterium avium-M. intracellular isolates from patients with acquired immunodeficiency syndrome (AIDS), patients without AIDS, and diseased animals. Against the isolates from humans without AIDS, the quinolone compounds difloxacin and A-56620 were found to be the most effective, each inhibiting 50% of strains at a concentration of 2 micrograms/ml. The remaining antimicrobial agents had MICs for 50% of strains tested of at least 32 micrograms/ml. Statistically significant differences were observed in the antibiogram patterns among the M. avium-M. intracellulare strains from each of the three sources.

Acquired Immunodeficiency Syndrome↗
PubMed1988

In vitro susceptibilities of Mycobacterium tuberculosis to 10 antimicrobial agents.

After preliminary in vitro screening of 10 antimicrobial agents against Mycobacterium tuberculosis, the MICs of the 6 most promising agents against 27 clinical isolates were determined by agar dilution. The two quinolone compounds tested (difloxacin and A-56620) were the most active, each inhibiting 50% of the strains at concentrations of 4 micrograms/ml. M. tuberculosis strains previously shown to be resistant to isoniazid, streptomycin, rifampin, or ethambutol were as susceptible to these quinolone compounds as susceptible strains.

Anti-Bacterial Agents↗
PubMed1988

Botulism from chopped garlic: delayed recognition of a major outbreak.

Diagnosis of botulism in two teenaged sisters in Montreal led to the identification of 36 previously unrecognized cases of type B botulism in persons who had eaten at a restaurant in Vancouver, British Columbia, during the preceding 6 weeks. A case-control study implicated a new vehicle for botulism, commercial chopped garlic in soybean oil (P less than 10(-4)). Relatively mild and slowly progressive illness, dispersion of patients over at least eight provinces and states in three countries, and a previously unsuspected vehicle had contributed to prolonged misdiagnoses, including myasthenia gravis (six patients), psychiatric disorders (four), stroke (three), and others. Ethnic background influenced severity of illness: 60% of Chinese patients but only 4% of others needed mechanical ventilation (P less than 10(-3]. Trypsinization of serum was needed to show toxemia in one patient. Electromyography results with high-frequency repetitive stimulation corroborated the diagnosis of botulism up to 2 months after onset. Although botulism is a life-threatening disease, misdiagnosis may be common and large outbreaks can escape recognition completely.

Botulinum Toxins↗
PubMed1987

Endemic institutional strongyloidiasis in British Columbia.

The incidental finding in 1984 of Strongyloides stercoralis larvae in a resident of a chronic care institution who had a vague clinical illness prompted a review of the other residents. Five other cases were identified after exhaustive laboratory investigations. Fecal-oral spread was considered the most likely manner of the spread of infection. The possibility of endemic strongyloidiasis in institutions should be considered, even in temperate climates, when there is unexplained persistent illness or high eosinophil counts. Serologic testing is a useful adjunct to fecal examination in such situations.

Adult↗
PubMed1987

In vitro activity of Ro 15-8074, Ro 19-5247, A-56268, and roxithromycin (RU 28965) against Neisseria gonorrhoeae and Chlamydia trachomatis.

In vitro Ro 15-8074 and Ro 19-5247 (T2525), two new oral cephalosporins, were active against 410 penicillin-susceptible and -resistant isolates of Neisseria gonorrhoeae. Two new macrolides, A-56268 and to a lesser extent roxithromycin (RU 28965), were active against Chlamydia trachomatis. A-56268 had activity against N. gonorrhoeae similar to that of erythromycin.

Anti-Bacterial Agents↗
PubMed1987

Inner-city survey for tuberculosis: evaluation of diagnostic methods.

A total of 1,271 persons living in a socially and economically depressed, inner-city area of Vancouver, British Columbia, voluntarily attended a tuberculosis case-finding campaign. Chest x-ray, on-the-spot specimen of sputum, and tuberculin skin test were offered at the time of the first attendance. All 3 diagnostic methods were found to be well accepted, with 93% of the participants having an x-ray, over 95% producing a sputum specimen, and almost 95% having a tuberculin test (a quarter of these did not, however, report for reading of the test). Eight cases of bacteriologically confirmed pulmonary tuberculosis were found: 6 suspected on x-ray (the remaining 2 films were abnormal but not diagnostic of tuberculosis), and 6 being positive on smear and/or culture of the initial on-the-spot sputum specimen. Examination of a second specimen of sputum diagnosed all of the 8 active cases identified by the survey. These results suggest that, in this particular setting, a chest radiogram taken by a transportable chest x-ray apparatus or examination of 2 sputum specimens might be equally successful at detecting all cases of active pulmonary tuberculosis within the time required for sputum culture. Examination of the sputum smear immediately identifies all the more infectious cases of pulmonary tuberculosis. The prevalence rate of 629 per 100,000 among those presenting themselves to this campaign illustrates the high-yield which might be achieved by active case-finding projects in known high-incidence segments of a generally low-incidence population.

Adult↗
PubMed1986

In-vitro susceptibility of 400 isolates of Neisseria gonorrhoeae in Vancouver, 1982-84.

Consecutive isolates of Neisseria gonorrhoeae obtained at a sexually transmitted disease clinic in Vancouver between June 1982 and June 1984 were tested for in-vitro susceptibility to eight antimicrobial agents. Of the 400 isolates 6 (1.5%) were penicillinase-producing N. gonorrhoeae, and for 25 (6.2%) the minimum inhibitory concentrations (MICs) of penicillin were 1.0 to 4.0 micrograms/ml. Ceftriaxone sodium was the most active agent. The MICs were higher than those reported in a Canadian study in 1973-74, except for tetracycline hydrochloride. The patterns of susceptibility of the isolates to one antimicrobial agent correlated significantly with those to each other agent, although the relation was weakest for trimethoprim-sulfamethoxazole and spectinomycin. The results reinforce the need to evaluate local in-vitro susceptibility patterns, especially since the proportion of isolates with relative and absolute resistance to penicillin is increasing.

Anti-Bacterial Agents↗
PubMed1986

In vitro activity of difloxacin hydrochloride (A-56619), A-56620, and cefixime (CL 284,635; FK 027) against selected genital pathogens.

Management of sexually transmitted diseases is facilitated by having antimicrobial agents with activity against all of the major genital pathogens. Newer quinolones show promise of being active against Neisseria gonorrhoeae and Chlamydia trachomatis. Two quinolones, difloxacin (A-56619) and A-56620, and an oral cephalosporin, cefixime (CL 284,635; FK 027), were evaluated in vitro. All three were highly active against 400 isolates of N. gonorrhoeae, including penicillinase-producing N. gonorrhoeae, N. gonorrhoeae with chromosomally mediated resistance, and isolates with penicillin MICs of less than 1 microgram/ml. Susceptibilities to one antimicrobial agent were usually strongly correlated with susceptibilities to the other antimicrobial agents evaluated, but isolates with increasing resistance to beta-lactams were least likely to show increasing resistance to quinolones. Difloxacin and, to a lesser extent, A-56620 were active against all 10 strains of C. trachomatis, and both had moderate activity against over 200 strains of Gardnerella vaginalis. Based on in vitro activity, difloxacin and A-56620 merit in vivo assessment for management of both C. trachomatis and N. gonorrhoeae infections, and cefixime shows considerable promise for treatment of N. gonorrhoeae infections.

Anti-Bacterial Agents↗
PubMed1985

Strongyloidiasis in Canadian Far East war veterans.

A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes.

Aged↗
PubMed1985

Isolation and geographic distribution of Mycobacterium other than M. tuberculosis in British Columbia, 1972-81.

It has been suggested that the incidence of infection with mycobacteria other than typical tubercle (MOTT) bacilli is increasing. Laboratory and epidemiologic information relating to MOTT infection in British Columbia between 1972 and 1981 was analysed. Patient records for 1960-81 were also analysed. Of the 313 661 laboratory specimens 13 474 yielded Mycobacterium tuberculosis isolates and 3172, MOTT isolates. Over the 10 years the number of M. tuberculosis isolates declined, whereas the absolute and relative numbers of MOTT isolates increased. Members of the highly drug-resistant MAIS complex (M. avium-intracellulare, M. scrofulaceum and M. simiae) accounted for 73.3% of the 1778 potentially pathogenic MOTT isolates. MAIS isolation rates varied geographically. Analysis of patient records revealed 217 MOTT infections, of which 152 (70%) were due to MAIS organisms. Further studies are needed to determine the source of MAIS organisms in order that the infection and the disease may be more clearly understood.

British Columbia↗
PubMed1985

Microscopic evaluation of sputum specimens submitted for Mycobacterium tuberculosis culture.

Using microscopic screening criteria employed in the study of sputum in acute bacterial pneumonia, the authors evaluated 644 sputum samples from 347 patients submitted for mycobacterial bacterial culture. After microscopic examination, these specimens were processed using standard mycobacterial laboratory technics. Salivary specimens accounted for 67.1% of the samples evaluated, and yielded 13 of the total 42 Mycobacterium tuberculosis isolates, as well as 4 of the 21 smear-positive culture-positive specimens. Although specimens from the lower respiratory tract are preferred, specimens of a salivary nature should not be discarded by the Mycobacteriology Laboratory.

Cells, Cultured↗