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Biomedical subjects

C H Chau

Publications and source records attributed to C H Chau.

At least 37 records · Page 2Linked to original sources

Is inhaled corticosteroid useful as adjunctive management in tuberculous pyrexia?

Systemic corticosteroid is currently the standard adjunctive therapy for tuberculous pyrexia. A preliminary prospective open study to examine the efficacy of inhaled budesonide at a dose of 2,400 micrograms daily in the management of this condition was performed. Out of nine non-HIV infected patients with tuberculous pyrexia studied, four patients succeeded to achieve defervescence at a mean of 3.25 days (range = 2 to 5 days), while the rest of the patients failed to do so within 7 days. None of the patients had unwanted side effects of systemic corticosteroid and patients' acceptance of such therapy was high. The potential usefulness of inhaled corticosteroid in some patients with tuberculous pyrexia might warrant further evaluation.

Administration, Inhalation↗

Fibreoptic bronchoscopy in the diagnosis of lung cancer.

A total of 562 patients with lung cancer was evaluated by fibreoptic bronchoscopy (FOB) by three bronchoscopic diagnostic procedures: biopsy, bronchial brushing and bronchial washing. Endoscopically visible tumours (EV) were detected in 264, while 257 had endoscopically nonvisible tumours > or = 2 cm in diameter and FOB was done without fluoroscopy because of limited availability (ENV). Forty-one had small (< 2 cm), endoscopically nonvisible tumours with FOB performed under uniplanar fluoroscopy (ENV + F). The overall diagnostic yield rates of FOB were 98.1%, 61.5% and 58.5% for the EV, ENV and ENV + F cases, respectively. Reviewing the differential yield rates of the three diagnostic techniques and comparing them with the results of previous studies led to the following conclusions. (1) Combinations of biopsy with brushing and biopsy with washing can diagnose more than 95% of all fibreoptic bronchoscopy positive cases with endoscopically visible tumours. Performing either of these combinations may be more cost-effective than doing all three techniques routinely. (2) For cases with endoscopically nonvisible tumours, performance of all three diagnostic techniques is recommended, especially when fibreoptic bronchoscopy is performed without fluoroscopic guidance, as washing and brushing seem to compensate for a lower yield of the biopsy. (3) For tumours < 2 cm in diameter, knowledge on the diagnostic efficacy of fibreoptic bronchoscopy was limited owing to the small size of previous studies. The yield of 58.5% for fibreoptic bronchoscopy in these patients with performance of all three diagnostic procedures was comparatively high. It could be further increased to 75.6% if supplemented by percutaneous needle biopsy when fibreoptic bronchoscopy turned out to be nondiagnostic. If available, the use of transbronchial needle aspiration may also increase the overall diagnostic yield of fibreoptic bronchoscopy in these cases.

Biopsy↗

Serum pharmacokinetics of antimycobacterial drugs in patients with multidrug-resistant tuberculosis during therapy.

Serum samples of 13 patients with multidrug-resistant tuberculosis were taken 0, 1, 2, 4, 8 h after administration of antimycobacterial drugs for assay of levels in order to gain further insight into their basic pharmacokinetics. The drugs assessed were amikacin, kanamycin, ofloxacin, levofloxacin, para-aminosalicylic acid, prothionamide, cycloserine, pyrazinamide and ethambutol. Techniques used for assay were reversephase high-performance liquid chromatography, gas liquid chromatography and fluorescent polarization immunoassay. The results from 12 patients were evaluated. These provided new pharmacokinetic data on high-dose levofloxacin, cycloserine and prothionamide given once daily, and could be useful in guiding the scheduling of drugs. The data obtained might also lead to insights into the development of therapeutic drug monitoring in multidrug-resistant tuberculosis.

Adult↗

Future directions in the development of new antitubercular drugs. Where do we go from here?

The global resurgence of tuberculosis and rampant drug resistance have rekindled the need for and interest in the development of new antitubercular drugs. Delineation of the possible drug targets furnished by the various mycobacterial cell components might result in rational approaches to the development of such agents. In the future, molecular genetics might help both in the bioengineering and rapid screening of the activity of new compound. Collaboration is anticipated between the pharmaceutical industry and academic institutions in these areas.

Antitubercular Agents↗

Changes in glycosaminoglycans during regeneration of post-crush sciatic nerves of adult guinea pigs.

The glycosaminoglycans of sciatic nerves recovering from crush-injury were studied in adult guinea pigs and compared with those of non-injured mature neural tissues. The glycosaminoglycans were recovered from the 1,900 g supernatant and pellet of the tissue homogenates and assayed for hexuronate contents and susceptibilities to hyaluronidase, chondroitinase ABC, and nitrous acid. In the normal brain and central nerve tracts, the glycosaminoglycans were distributed both in the supernatant and pellet fractions; the brain showed a predominance of chondroitin sulphates but the tracts showed a predominance of heparan sulphates. Twice as much glycosaminoglycans were found in normal sciatic nerves, only in the pellet fraction and with heparan sulphate predominant. In the 2 weeks post-crush, progressive increase in hexuronate was observed, due mainly to additional chondroitin sulphate forms in the supernatant; the pellet fraction in the same period was however similar to the untreated controls in relative abundance of glycosaminoglycan classes and hexuronate content. At 4 weeks post-crush, although the total hexuronate returned to the control level, a significant proportion of glycosaminoglycans remained in the supernatant fraction. Evidence is thus provided for the need to modulate the glycosaminoglycan expression pattern in adult neural tissue to allow post-traumatic tissue remodelling and axonal regrowth.

Animals↗

Oral fluconazole in the treatment of pulmonary cryptococcosis in non-AIDS patients.

Four non-AIDS patients with pulmonary cryptococcus infection who could not tolerate amphotericin B treatment were given oral fluconazole at a dose of 600 mg once daily for 4-5 weeks followed by 400 mg once daily for 10-12 weeks resulting in cure. All patients did not have relapse of disease when followed-up for 8-24 months after cessation of treatment. The very good tolerance of oral fluconazole by these patients suggests that such effective monotherapy should be evaluated further in non-AIDS patients with pulmonary cryptococcosis.

Adult↗

New antimycobacterial agents.

The resurgence of tuberculosis and the increased prevalence of atypical mycobacterial infections in immunocompromised subjects have prompted the quest for novel antimycobacterial agents. Fluoroquinolones, such as ofloxacin and ciprofloxacin, might be promising agents for treatment of tuberculosis especially multidrug-resistant tuberculosis (MDR-TB) and infections caused by Mycobacterium fortuitum. Clarithromycin, an important member of the macrolides, has been shown to have activity against some infections due to Mycobacterium avium-intracellulare, M. fortuitum and Mycobacterium chelonae. Rifabutin, being a rifamycin, has been found to be efficacious in treatment of drug-susceptible tuberculosis, although its place in MDR-TB is less certain. Rifabutin in combination with other drugs might constitute active regimens for treatment of disseminated M. avium-intracellulare infections. When used alone, it can be an active prophylactic agent against such infection. Imipenem, a carbapenem, might provide promising treatment for some M. fortuitum and M. chelonae infections. The place of beta-lactam-beta-lactamase inhibitor combinations in the treatment of MDR-TB is uncertain. Clofazimine and aminosidine being riminophenazine and aminoglycoside, respectively, might merit further evaluation as potentially useful agents for treatment of MDR-TB and M. avium-intracellulare infections. However, much broader evaluation of all these agents in clinical settings is still definitely required.

Anti-Infective Agents↗

Low-dose methotrexate in the management of Chinese patients with steroid-dependent asthma.

Nine Chinese patients with severe asthma who were dependent on a systemic oral steroid for control were given oral methotrexate at a dose of 7.5 mg on alternate days for two weeks, followed by 15 mg once weekly. Only six patients were evaluable; they had received methotrexate for 6 to 24 months. All six patients could have reduction of daily oral prednisolone dosage by 5-15 mg (mean: 10.4 mg). Only four patients, however, had > or = 15% improvement of their best peak expiratory flow rates compared with baseline levels, though all six patients had symptomatic improvement. These beneficial effects were, however, transient and persisted only during methotrexate therapy. Four patients had liver enzyme changes and discontinuation of therapy was required in one patient. One patient also had infective spondylitis secondary to Salmonella bacteremia. Thus low-dose oral methotrexate may be useful in selected patients with severe steroid-dependent asthma with careful monitoring for response and drug toxicity.

Adult↗

Ciprofloxacin-induced renal dysfunction in patients with mycobacterial lung infections.

3 patients with mycobacterial lung infections, one due to Mycobacterium avium-intracellulare and 2 due to M. tuberculosis, developed ciprofloxacin-induced acute renal dysfunction while receiving the drug together with other antimycobacterial agents. These episodes took place 8-10 days after commencement of therapy and recovered spontaneously after cessation of all antimycobacterial drugs for 2-8 weeks. No recurrence was noted when patients were restarted on regimens that did not contain ciprofloxacin.

Acute Kidney Injury↗

Drug-resistant tuberculosis in the 1990s.

There has been an upsurge of tuberculosis in many parts of the world in the past decade. The high rates of drug-resistant tuberculosis currently reported in many countries are alarming. The most catastrophic phenomenon is the emergence of multidrug-resistant strains of Mycobacterium tuberculosis. These organisms have caused epidemic outbreaks in nosocomial and health-care settings in the USA and some European countries. In addition to immigration, poverty, alcoholism and intravenous substance abuse, human immunodeficiency virus (HIV) infection has also had a significant impact on the prevalence of drug resistance, since amongst these patient groups a common factor giving rise to drug resistance is noncompliance. Rapid drug susceptibility tests are needed, and effective chemotherapy regimens with newly developed drugs in combination with traditional second-line antituberculosis agents for established multidrug-resistant tuberculosis are urgently being sought. There is also a quest for other novel modalities of therapy. Measures should be actively adopted to prevent the development of drug resistance. Well formulated short-course chemotherapy as initial treatment and ensurance of compliance are the most important components. The organization of a national tuberculosis control programme with a sound and adequately functioning infrastructure remains the most effective strategy to combat the resurgence of tuberculosis and to curtail drug resistance.

AIDS-Related Opportunistic Infections↗

Ciprofloxacin in the management of pulmonary tuberculosis in the face of hepatic dysfunction.

Twenty-five patients who had extensive pulmonary tuberculosis and hepatitis induced by antituberculosis drugs were treated with ciprofloxacin together with other relatively non-hepatotoxic drugs, either during the interim phase awaiting recovery of liver function in some, or as definitive therapy as required by the compromised hepatic status of others. Only 22 patients were assessable. All tolerated ciprofloxacin well during the phase of hepatic dysfunction. All patients improved with these ciprofloxacin-containing regimens, but the optimal dosage, specific efficacy and long-term safety of the drug in such cases require further evaluation.

Adult↗