Biomedical subjects

O Tan

Publications and source records attributed to O Tan.

4 recordsLinked to original sources

PubMed1999

A new approach to bladder augmentation in children: seromuscular enterocystoplasty.

OBJECTIVE: To report the use of seromuscular enterocystoplasty (SE) combined with detrusorectomy, in children. PATIENTS AND METHODS: Between 1993 and 1998, SE was performed in 10 children (aged 10-17 years) with a spastic neurogenic bladder resulting from spinal trauma. Before surgery all children were incontinent and despite anticholinergic medication and clean intermittent catheterization, their bladder capacity was 60-100 mL and their intravesical pressure 40-60 cmH2O. RESULTS: Before surgery, the mean end-filling intravesical pressure was 47.7 cmH2O and the mean bladder capacity 82.9 mL. At 3 months after surgery the mean end-filling intravesical pressure was decreased to 21.1 cmH2O and the mean bladder capacity increased to 319.6 mL. One patient (a 14-year-old girl) had urinary retention soon after surgery and has since used clean intermittent catheterization. The other children were able to void successfully using the Valsalva manoeuvre; none were incontinent. All patients were followed and there were no changes in intravesical pressure and bladder capacity. CONCLUSION: In providing most of the desired features of an ideal augmentation segment, SE is a good and effective method of bladder augmentation.

Adolescent↗

PubMed1995

Optimization of MR pulse sequences for Bayesian image segmentation.

A method for optimizing MR imaging pulse sequence parameters in a statistical framework is presented. Parameters are defined to be optimal when the resulting scalar images yield optimal image segmentations using Bayesian pixel classification. Thus, Bayes risk is used as the objective function to minimize. Approximations are made to give a tractable solution in a four-step procedure. A sample calculation is carried out to determine the optimal TR and flip angle for scalar SPGR imaging of the brain. Overall, this paper gives a new approach to optimize MRI pulse sequences for the specific objective of improved image segmentation.

Bayes Theorem↗

PubMed1977

Prevention of experimental allergic encephalitis in guinea-pigs with spinal cord protein: optimum pretreatment schedules and appraisal of plausible mechanisms.

Pretreatment of Hartley guinea-pigs with three injections of 100 microgram of the purified bovine spinal cord protein, (SCP), protected tham from clinical experimental allergic encephalitis (EAE) when they were subsequently challenged with 50 microgram of purified bovine myelin basic protein (MyBP) in Freund's complete adjuvant (FCA). The length of the optimum pretreated schedule was found to be 1 week and the animals were fully protected for 2 weeks. Protection declined thereafter so that by 4 weeks following pretreatment only 40% of the animals were protected. The protected state could be restored several weeks after it had lapsed by repeating the treatment with SCP. Immature animals did not respond well to pretreatment with SCP. Evidence was presented to indicate that specific, non-specific immune suppression or anti-SCP IgG were not involved to a significant extent in protection. SCP-treated guinea-pigs regularly displayed delayed skin hypersensitivity to MyBP after sensitization but there was no correlation between the degree of cutaneous reactivity and protection from disease. Because SCP is localized in the nerve axon, the speculation was advanced that anti-SCP blocking factors might be responsible for preserving axonal function in SCP-treated animals sensitized with MyBP.

Animals↗

PubMed1976

Further characterization of the anti-encephalitogenic protein (SCP): isolation from bovine spinal cord and spinal roots.

The three molecular forms of the anti-encephalitogenic protein, beta-SCP, gamma-SCP, and SCP-peptide were isolated in higher yield by a shortened procedure, which involved 1) extraction of bovine spinal cord (BSC) or bovine spinal roots (BSR) with 0.05 M sodium acetate buffer, pH 4.5, 2) batch absorption on CM-52 cellulose, 3) stepwise elution with sodium acetate buffers, pH 5.8, containing increasing concentrations of sodium chloride and finally, 4) removal of trace contaminants by gel-exclusion chromatography on Sephadex G-50 superfine. The m.w. of the purified proteins determined by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis was 13,200 daltons. The same value for the molecular sizes was obtained by gel-exclusion chromatography by using 0.1% SDS in 0.05M sodium chloride as eluant. In the absence of SDS the molecular sizes estimated by gel exclusion chromatography ranged from 14,000 to 18,500. The amino acid compositions of the beta-SCP and gamma-SCP from BSC and BSR were similar except that beta-SCP from BSR lacked half-cystine whereas gamma-SCP from BSR contained three times as much half-cystine as the SCP forms prepared from BSC. All forms of SCP showed reactions of identity when compared by immunodiffusion analyses with a rabbit anti-bovine SCP serum; none formed precipitin lines with a rabbit anti-bovine myelin basic protein (MyBP) serum.

Amino Acids↗