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Biomedical subjects

C T Le

Publications and source records attributed to C T Le.

At least 19 recordsLinked to original sources
PubMed1992

A clinical profile of otitis media.

An otitis media with effusion algorithm developed by Paradise et al and tested by Cantekin et al has become the basis for many studies of otitis media. However, a two-point scale algorithm (otitis media with effusion-no otitis media with effusion) may be too ambitious (ie, low specificity) and too optimistic (ie, absence of fluid does not necessarily mean normal ear). We propose a four-point profile that characterizes the condition of the middle ear, and we report the validation of the profile against findings at myringotomy. Statistically, a four-point scale profile would substantially increase powers of statistical tests, compared with a two-point scale algorithm (in studies of the same size), when used to study changes of the middle-ear condition over time or to compare treatment effects.

Acoustic Impedance Tests↗
PubMed1992

Effects of glucose, Trolox-C, and glutathione disulphide on lipid peroxidation and cell death induced by oxidant stress in rat heart.

OBJECTIVE: The aim was to find effective protection of myocytes against peroxide induced damage in terms of preservation of contractile activity, protection against lipid peroxidation, and protection against cell death. METHODS: The components of the glutathione redox cycle, the production of malondialdehyde, cell contractions, and enzyme release from myocytes were measured in cultured neonatal rat heart cells before and after administration of cumene hydroperoxide, 80 mumol.litre-1. The protective action was tested of (1) glucose (10 mmol.litre-1) which stimulates the production of NADPH; (2) Trolox-C (0.16 mmol.litre-1) which is a water soluble analogue of alpha tocopherol and a scavenger of free radicals; and (3) GSSG (0.6 mmol.litre-1) which increases the intracellular concentrations of GSH and GSSG. RESULTS: Although the three substances tested were equally effective in reducing the formation of malondialdehyde, exogenous GSSG afforded only slight protection against cumene hydroperoxide induced cell death, whereas glucose and Trolox-C were highly effective protectors. The depressant effect of cumene hydroperoxide on beating frequency was not influenced by preincubation with GSSG, nor by coadministration of glucose, but Trolox-C was able to diminish the negative chronotropic action of cumene hydroperoxide. CONCLUSIONS: Effective protection against cumene hydroperoxide induced lipid peroxidation is not associated per se with effective protection against cumene hydroperoxide induced loss of beating frequency and cell death.

Animals↗
PubMed1991

Homogeneity of the relative risk in cohort studies.

We propose a statistical method to test the homogeneity of relative risk in cohort studies. We illustrate its application to an original data set from a low-risk group of end-stage renal disease patients on haemodialysis. The use of the method is as a global test against the omnibus alternative.

Age Factors↗
PubMed1991

Evaluation of ventilating tubes and myringotomy in the treatment of recurrent or persistent otitis media.

In a prospective controlled study of the efficacy and sequelae of ventilating tubes, 44 children with bilateral recurrent acute otitis media (greater than 6 episodes/year) and 13 children with bilateral persistent middle ear effusion (greater than 3 months) received unilateral ventilating tube insertion in a randomly selected ear. The contralateral ears were randomized to receive either myringotomy alone or no surgery. Clinical, otoscopic, tympanometric and audiologic examinations were performed before the study and 2 to 4 weeks later, then at 3-month intervals for up to 2 years and at 36 months after surgical randomization. Medical therapy and antibiotic prophylaxis were used whenever indicated. While the ventilating tubes remained functional (mean duration, 10 months) the ears with a tube had significantly fewer episodes of otitis media than their contralateral ear (P less than 0.001; 95% confidence intervals -0.7, -1.7) and had more hearing improvement (P = 0.005; 95% confidence intervals, -5.9, -1.2). After tube extrusion there was a tendency for surgically treated ears to have more otitis and worse hearing, but not at a significant level. Tympanosclerosis, retraction and atrophy were more common in ears that received tubes. The majority of ears treated medically also improved. There is need for a more cautious and selective use of ventilating tubes.

Acoustic Impedance Tests↗
PubMed1991

Resolution of otitis media with effusion with the use of a stepped treatment regimen of trimethoprim-sulfamethoxazole and prednisone.

This double blind, placebo-controlled trial was designed to determine whether intervention with a stepped regimen of trimethoprim-sulfamethoxazole (TMP-SMX) and prednisone would prevent high risk children from developing chronic otitis media with effusion (OME) and recurrent acute otitis media. Forty-two children were enrolled, assigned to treatment with active drug or placebo and then examined at 2-week intervals. They received TMP-SMX (or placebo) during the first 2 weeks, TMP-SMX and prednisone (or placebo) during Weeks 3 and 4 for persistent OME and TMP-SMX (or placebo) for Weeks 5 and 6 if OME was still unresolved. After treatment 48% of active drug and 14% of placebo subjects resolved OME bilaterally (P less than 0.05). Active drug subjects also had fewer acute otitis media episodes than placebo subjects while receiving study treatment (P less than 0.01). Although this treatment regimen produced short term OME resolution, long term benefits were not demonstrated.

Child↗
PubMed1991

Cellular changes in Reissner's membrane in endolymphatic hydrops.

A quantitative morphologic study of the cellular changes in human Reissner's membrane (RM) was performed under light microscopy on 30 normal temporal bones from 15 subjects, and on 20 temporal bones from 10 subjects with endolymphatic hydrops. The cellular density of the epithelial and mesothelial layers of normal RMs decreased with increasing age. In endolymphatic hydrops, cellular proliferation and decreased cellular density of a distended RM were observed, and these changes occurred more remarkably in epithelial cells. Decreased cellular density in RM was correlated to the degree of endolymphatic hydrops. These findings indicate an involvement of the epithelial cellular changes in the pathogenesis of endolymphatic hydrops. Our results suggest that cellular changes in RM may cause dysfunction of radial flow leading to ionic disturbance of endolymph, which provides a possible mechanism of hearing loss in endolymphatic hydrops.

Adolescent↗
PubMed1991

Relative value of diagnostic tests for small acoustic neuromas.

Auditory brainstem response is now widely employed as a screening test for acoustic neuromas because it is equally sensitive when standardized against computed tomography. We have detected eight small (less than 10 mm) acoustic neuromas using gadolinium enhanced magnetic resonance imaging. In three of these cases, the auditory brainstem response was falsely negative. In contrast, 19 patients with larger tumors (greater than or equal to 10 mm) were found to have no false negative auditory brainstem responses. Auditory brainstem response appears to be less sensitive for detecting small, symptomatic acoustic neuromas.

Adult↗
PubMed1991

Tests of homogeneity for the relative risk in multiply-matched case-control studies.

We examine several tests of homogeneity of the odds ratio in the analysis of 2 x 2 tables arising from epidemiologic 1:R matched case-control studies. The T4 and T5 statistics proposed by Liang and Self (1985, Biometrika 72, 353-358) are unable to detect obvious inhomogeneity in two numerical examples and in simulation studies. The null hypothesis is rejected by the chi-square statistic of Ejigou and McHugh (1984, Biometrika 71, 408-411) and by a new proposed method whose significance level must be simulated.

Biometry↗
PubMed1990

Statistical methods for determining risk factors of chronic otitis media with effusion.

We use logistic regression with paired Bernouilli outcomes to analyse data on subjects who have either one or two organs (e.g. ears) each of which may develop disease. In this model, subject-specific covariates are related to the probability of developing disease. The proposed method is applied to determine risk factors for chronic otitis media with effusion.

Analysis of Variance↗
PubMed1990

An experimental model for measuring middle ear antimicrobial drug penetration in otitis media.

Bacteria are an important cause of acute otitis media and successful treatment depends on achieving inhibitory or bacteriacidal antimicrobial drug concentrations in the middle ear. To evaluate further otitis media treatment success and failure, we developed a chinchilla model to study antimicrobial drug penetration through the middle ear mucosa. Using quantitative histomorphometry, we measured the middle ear space in 10 chinchillas and found a mean +/- SD volume of 2.09 +/- 0.08 ml and a mean +/- SD surface area of 14.41 +/- 1.48 cm2. To measure the apparent rate constant (Kc) of antibiotic elimination from the middle ear, through the middle ear mucosa, an antibiotic solution was inoculated into the middle ear cavity, and samples were aspirated between 1 and 8 hr later. In normal ears, the mean Kc +/- SD for amoxicillin was 0.118 +/- 0.013 hr-1, that for a trimethoprim 0.461 +/- 0.090 hr-1, and that for sulfamethoxazole 0.265 +/- 0.062 hr-1. In ears inoculated with type 7F Streptococcus pneumoniae to induce acute otitis media, the Kc +/- SD increased for all three drugs (P less than 0.05): amoxicilin to 0.286 +/- 0.089 hr-1, trimethoprim to 0.662 +/- 0.118 hr-1, and sulfamethoxazole to 0.411 +/- 0.056 hr-1. These values demonstrate that amoxicillin had the lowest apparent penetration rate constant of the three antibiotics but the greatest increase from normal to infected mucosa (142%). Trimethoprim had the highest apparent penetration rate constant of the three antibiotics but the smallest increase from normal to infected mucosa (44%), while the sulfamethoxazone apparent penetration rate constant increased from normal to infected mucosa by 55%.(ABSTRACT TRUNCATED AT 250 WORDS)

Amoxicillin↗
PubMed1990

A controlled trial comparing three treatments for chronic otitis media with effusion.

A randomized, controlled clinical trial was conducted in 76 children to evaluate the efficacy of trimethoprim-sulfamethoxazole for 4 weeks, prednisone for 2 weeks and aluminum ibuprofen suspension for 2 weeks in resolving chronic otitis media with effusion which had persisted for more than 8 weeks. After 2 weeks of treatment resolution rates of chronic otitis media with effusion in the prednisone and trimethoprim-sulfamethoxazole groups were significantly greater than those in the control (no treatment) and ibuprofen groups. After 4 weeks the differences in resolution rates between the control, trimethoprim-sulfamethoxazole and prednisone groups became smaller. After 12 months of follow-up, differences in hearing sensitivity among study groups were not statistically significant, although 83% of patients had a 15-dB or greater hearing loss. Therefore short term antimicrobial and antiinflammatory treatment did not appear to have a long lasting effect on chronic middle ear inflammation.

Analysis of Variance↗
PubMed1989

Bronchodilation from intravenous theophylline in patients with cystic fibrosis: results of a blinded placebo-controlled crossover clinical trial.

Most patients with cystic fibrosis (CF) eventually develop chronic obstructive pulmonary disease and theoretically could benefit from theophylline therapy. The purpose of this study was to investigate the pharmacologic response to intravenous theophylline by pulmonary function tests (PFT) and the theophylline pharmacokinetics in patients with CF. A randomized, double-blind, placebo-controlled, crossover trial was conducted in 10 ambulant patients with CF (5 females, 5 males), aged 11 to 21 years. Each patient received an intravenous dose of theophylline and normal saline over 1/2 hour on consecutive days. Spirometry and whole-body plethysmography were performed at baseline, 1, 3, 5, and 7 h after the theophylline dose, and 10 blood samples were collected over 9 h on both study days. The percent change of PFT from the baseline was recorded. Analysis of variance for balanced two-period crossover design was used to evaluate the effectiveness of theophylline therapy. The serum concentration (Conc.) vs. time data were fitted using nonlinear least-squares regression analysis. The theophylline dose administered was 7.9 +/- 0.4 (mean +/- SD) mg/kg, which produced a maximal Conc. (Cmax) of 14.6 +/- 2.7 microgram/ml. The half-life (T1/2), volume of distribution (Vd), and total body clearance (TBC) were 4.9 +/- 1.9 h, 537 +/- 124 mL/kg, and 80 +/- 16 ml/h/kg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Experimental animal models for studying antimicrobial pharmacokinetics in otitis media.

Antimicrobial treatment of otitis media, especially drug dosing considerations, is largely empiric, with few reported pharmacologic studies of drug distribution into the middle ear. A chinchilla animal model of serous and purulent otitis media has been used for some time to investigate mechanisms of disease pathogenesis. This model was adapted to investigate the penetration of amoxicillin, trimethoprim, and sulfamethoxazole into middle ear effusion. Purulent otitis media was produced by direct middle ear inoculation with type 7F Streptococcus pneumoniae. Serous otitis media was produced by eustachian tube obstruction using silastic sponge or Coeflex cement, but the Coeflex caused an undesirable local inflammatory response. The three antibiotics were administered to chinchillas with serous and purulent middle ear effusion. Plasma and ear fluid drug concentrations were measured by liquid chromatography and demonstrated the value of this model in assessing antibiotic penetration.

Amoxicillin↗
PubMed1988

Randomization using packaged programs.

The problem of implementation of a randomization in controlled clinical trials is briefly discussed. A computer procedure is proposed and illustrated with simple programs using BMDP, SAS, and SPSS.

Clinical Trials as Topic↗