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Biomedical subjects

R Teoh

Publications and source records attributed to R Teoh.

At least 37 records · Page 2Linked to original sources
PubMed1988

Suprasellar tuberculoma developing during treatment of tuberculous meningitis requiring urgent surgical decompression.

An adult patient on treatment for tuberculous meningitis developed visual failure due to a tuberculoma compressing both optic nerves and chiasm. Although continued anti-tuberculous chemotherapy is the treatment of choice for intracranial tuberculoma, the rapid deterioration in vision necessitated urgent surgical decompression, which resulted in complete recovery of vision.

Adult↗
PubMed1988

Epstein-Barr virus genome in thymoma and thymic lymphoid hyperplasia.

In a study of 23 consecutive thymectomies from patients with myasthenia gravis (MG), 10 (43.5%) were thymomas, 8 (34.8%) were thymic lymphoid hyperplasia (TLH), and 5 (21.7%) were normal/involuted thymuses. The incidence of thymoma in MG appears to be considerably higher in Hong Kong than in similar series from Western countries. Six patients from this group were examined for the presence of Epstein-Barr virus (EBV) genome by Southern blot, as were a thymoma from a patient without MG, a patient with TLH in the absence of MG, and 3 normal control thymuses. All 3 thymomas (2 of 2 with MG, 1 of 1 without MG), 2 of 4 TLH with MG, and 1 of 1 TLH without MG were positive for EBV genome. Thymoma should be included, along with nasopharyngeal carcinoma and malignant lymphoepithelial lesions of the salivary gland, as EBV-related epithelial tumors, all of which are prevalent in this region.

Adult↗
PubMed1988

Pyrazinamide and rifampicin regimens for patients on maintenance dialysis.

We measured pyrazinamide and rifampicin plasma concentrations in five patients with pulmonary tuberculosis and end stage renal failure treated by haemodialysis or continuous ambulatory peritoneal dialysis. Using conventional daily doses of oral pyrazinamide and rifampicin, we found that the drugs were removed efficiently by both dialysis methods, so that plasma levels were sub-optimal for maximal bactericidal action. These findings suggest that in patients with tuberculosis on maintenance dialysis, treatment should be either with higher doses of these two drugs, or with additional replacement doses given after each dialysis. Further detailed pharmacokinetic studies on larger numbers of patients are indicated.

Adolescent↗
PubMed1987

Liquid chromatographic assay for the simultaneous determination of pyrazinamide and rifampicin in serum samples from patients with tuberculous meningitis.

A simple high-performance liquid chromatographic assay for the simultaneous determination of pyrazinamide and rifampicin in serum from patients with tuberculous meningitis is presented. The drugs and internal standard, p-acetamidobenzoic acid, were extracted from the acidified sample containing 2% ascorbic acid at pH 4.2 into dichloromethane-diethyl ether (2:3). The solvent extract was evaporated to dryness with the aid of nitrogen and the residue redissolved in methanol (75 microliters). The concentrate was analysed by a liquid chromatograph using a reversed-phase 30-microns C8 pre-column linked to a 5-microns C8 analytical column with a gradient solvent programme, which delivered 6% to 48% (v/v) acetonitrile in phosphate buffer (10 mM potassium dihydrogenphosphate, pH 3.5) in 10 min at 1.5 ml/min. The eluate was detected at 215 nm. Twelve patients with tuberculous meningitis were given daily chemotherapy, and their serum samples were assayed for pyrazinamide and rifampicin.

Calibration↗
PubMed1987

Diagnosis of tuberculous meningitis by detection of tuberculostearic acid in cerebrospinal fluid.

Tuberculostearic acid, a structural component of Mycobacterium tuberculosis, was identified by gas chromatography/mass spectrometry with selected ion monitoring in cerebrospinal fluid (CSF) from 13 patients with proven and 8 out of 9 patients with suspected tuberculous meningitis; the negative result was in a patient whose symptoms and CSF abnormalities may have been due to systemic lupus erythematosus. Tuberculostearic acid was found in the CSF of only 1 patient out of 87 with non-tuberculous meningitis or non-infectious disorders; the single false-positive result was probably caused by intrathecal treatment with amikacin. Other aminoglycosides and antituberculous drugs did not interfere with the assay. In serial CSF samples from patients with tuberculous meningitis tuberculostearic acid was still present after 8 months of continuous supervised chemotherapy. Detection of tuberculostearic acid in CSF is a rapid, sensitive, and specific test for tuberculous meningitis, and can be used for retrospective diagnosis in patients who have been started on therapy.

Adult↗
PubMed1987

Insulin binding and effects on pyrimidine nucleoside uptake and incorporation in cultured mouse astrocytes.

Binding of 125I-insulin to primary cultures of differentiated mouse astrocytes was time-dependent, reaching equilibrium after 2 h at 22 degrees C, with equilibrium binding corresponding to 20.79 fmol/mg of protein, representing approximately 5,000 occupied binding sites/cell. The half-life of 125I-insulin dissociation at 22 degrees C was 2 min, with an initial dissociation rate constant of 4.12 X 10(-2) s-1. Dissociation of bound 125I-insulin was not accelerated significantly in the presence of unlabeled insulin (16.7 microM). Porcine and desoctapeptide insulins competed for specific 125I-insulin binding in a dose-dependent manner, whereas growth hormone, glucagon, and somatostatin did not. For porcine insulin, Scatchard analysis suggested multiple-affinity binding sites (high-affinity Ka = 4.92 X 10(8) M-1; low-affinity Ka = 0.95 X 10(7) M-1). After incubation with insulin (0.5 microM) for 2 h at 37 degrees C, increases above basal values of 254 +/- 23 and 189 +/- 34% for [3H]uridine uptake and incorporation, respectively, were observed. After incubation with insulin (0.5 microM) for 24 h at 37 degrees C, there were increases of 145 +/- 6% for [3H]thymidine uptake and 166 +/- 11% for thymidine incorporation. Basal and stimulated uridine and thymidine uptake and incorporation were inhibited by 50 microM dipyridamole. These studies confirm that mouse astrocytes in vitro possess specific insulin receptors and demonstrate an effect of insulin on pyrimidine nucleoside uptake and incorporation.

Animals↗
PubMed1987

Symptomatic intracranial tuberculoma developing during treatment of tuberculosis: a report of 10 patients and review of the literature.

Ten patients with intracranial tuberculomata which developed during treatment for tuberculosis are described. The initial infection was meningeal in five, miliary in three and pulmonary in two and all improved after treatment was started. However 10 days to five months (mean two months) after the start of treatment, new neurological symptoms and/or signs occurred that led to the recognition of intracranial tuberculomata. CT brain scans suggested tuberculomata in all 10 patients; there were several lesions in five and histological confirmation was obtained in three cases. Earlier CT brain scans (six weeks to five months before) were carried out in five patients and in none was a tuberculoma seen. After treatment with anti-tuberculous drugs and control of raised intracranial pressure when present, five patients made a full recovery, three were left with mild neurological deficit and in two it is too early to assess the outcome.

Adolescent↗
PubMed1986

Polymorphonuclear pleocytosis in the cerebrospinal fluid during chemotherapy for tuberculous meningitis.

Five patients on chemotherapy for tuberculous meningitis developed sudden and unexpected cerebrospinal fluid pleocytosis consisting predominantly of polymorphonuclear leucocytes. The cellular changes, which developed 4-108 days after starting treatment, were not accompanied by an alteration in the clinical state and disappeared within a week whether or not an additional antibiotic was prescribed. Through the cause is uncertain, possible mechanisms are discussed. We are prompted to report these cases because the cytological changes are not well recognised and may cause difficulties in management.

Adult↗
PubMed1985

Effects of dimethyl sulfoxide on humoral immune responses to acetylcholine receptors in the rat.

The effects of dimethyl sulfoxide (DMSO) on the humoral immune responses to acetylcholine receptors (AChR) were studied in rats with experimental autoimmune myasthenia gravis. DMSO was administered during primary, ongoing, and secondary phases of the immune response to AChR. Anti-AChR antibody titers were measured to determine the effect of the treatment. DMSO had pronounced effects on the humoral immune response, which differed depending on the stage of the response and the strength of antigenic stimulation. When given during an ongoing immune response, DMSO suppressed anti-AChR antibody levels by an average of 53-76%. This effect was similar whether DMSO was given by oral, rectal, or intraperitoneal routes. DMSO treatment also suppressed the anti-AChR antibody response to a weak primary antigenic stimulus to a similar extent. In contrast, when administered during a secondary or a strong primary immunization, DMSO enhanced the anti-AChR antibody response 1.7- to 2.8-fold. These results show that DMSO may either enhance or suppress humoral immune responses. Further studies will be required to analyze the cellular mechanisms underlying the actions of DMSO.

Animals↗
PubMed1985

An improved gas liquid chromatographic assay for plasma valproic acid concentrations in mentally handicapped epileptic children.

A gas liquid chromatographic (GLC) method is described for the determination of valproic acid concentrations in plasma. This simple, rapid and reproducible assay involved chloroform (500 microliter) extraction of the drug and internal standard (octanoic acid) from acidified plasma samples. An aliquot (1 microliter) of the unconcentrated organic extract was injected directly into the GLC system (a coiled glass column 1 m long, 6 mm OD packed with 5% diethylene-glycol-succinate-phosphate on 100/120 mesh Supelcoport) with detection by flame-ionization. This assay was successfully employed to measure plasma concentrations of valproic acid in 42 mentally handicapped, epileptic children of Chinese origin, most of whom were on multiple anti-epileptic agents.

Child↗
PubMed1984

Whole blood cyanide levels in patients with tobacco amblyopia.

Three patients presented with painless bilateral visual failure due to tobacco amblyopia. The whole blood cyanide levels were raised above those predicted from their high tobacco consumption, approaching lethal levels reported from acute inhalation of cyanide. Each patient had an excessive alcohol intake with biochemical evidence of hepatic dysfunction, the elevated whole blood cyanide levels being attributed to the associated impairment of cyanide detoxification. In each case the improvement in visual acuities following abstinence and hydroxycobalamin therapy was accompanied by a reduction in the whole blood cyanide level to within the normal range. Serial measurements of whole blood cyanide, serum alcohol, and the detection of urinary nicotine provided valuable indices of the patient's subsequent compliance and clinical progress.

Adult↗