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Biomedical subjects

Y L Chang

Publications and source records attributed to Y L Chang.

142 records · Page 8Linked to original sources
PubMed1989

A new therapeutic parameter and computer control to approach optimal haemodialysis.

A two-compartmental (intracellular and extracellular volumes) patient model is being employed to derive the time variation of dialysis rate, which is required to meet the criterion that the intercompartmental concentration difference should not exceed the maximum value the patient could tolerate during dialysis treatment. Dialysate flow rate is the operational variable selected for controlling the dialysis rate. The maximum intercompartmental solute concentration difference allowable for individual patients is suggested as a new therapeutic parameter. The model algorithm and a personal computer can be linked with the delivery pump to monitor the dialysis treatment so as to avoid the disequilibrium syndrome and thus rationalise the entire procedure of dialysis.

Algorithms↗
PubMed1989

[Histological study of hydroxylapatite mixed with collagen as osseous implant in mandible].

By using five Taiwan Macaca monkeys as experimental animals, three bony defects about 5 x 5 x 3 mm in size were created at each of their buccal region of mandible. Bovine skin collagen and particulate hydroxylapatite were used as implant materials. The artificial defects implanted with hydroxylapatite/collagen mixture were experimental group and the defects implanted with collagen or without any implantation were control groups. The monkeys were sacrificed at the time of 1,2,3,6,9 months after implantation surgery and were injected with tetracycline according to the above intervals at one week before being sacrificed. The specimens were divided into two parts, one of which was decalcified and stained with hemotoxylineeiosin for observation under optic light microscope, the other without decalcification was made into ground section for observation under fluorescent microscope. The result revealed that the healing processes of the two control groups were similar with each other. Bone formation was delayed in HA/Collagen group because it took almost five months to achieve complete bony repair of the mandibular defect. However bone formation at the HA/Collagen implant site was earlier than that at the pure HA implant site in our similar study. What's the role of collagen that played during bone formation still needed further investigation. The tissue response was good without obvious inflammatory cells infiltration. Clinical application of block form of dried HA/Collagen mixture was suggested for it was easier to handle and could decrease the flow of HA particles after implantation.

Animals↗
PubMed1988

Basal joint reconstruction in a punch injury of the hand.

Severe hand trauma caused by an industrial accident resulted in composite tissue loss in the basal joint area of the right hand. The crushed metacarpal bone was replaced, and ligamentous and capsular reconstruction was performed with flexor carpi radialis tendon and additional tendon graft. We present our experience, with a follow-up of one year and eight months.

Accidents, Occupational↗
PubMed1988

Three successful digital replantations in a patient after 84, 86, and 94 hours of cold ischemia time.

Three successful digital replantations were performed on a patient after 84, 86, and 94 hours of prolonged cold ischemia time. Both the intraoperative and postoperative courses were smooth. Functional evaluation 8 months after operation revealed a normal speed of sensory recovery and nail growth. The atrophic changes in all three replants are mild. Total active movement was 45, 100, and 70 degrees in the replanted left thumb, left index finger, and right thumb, respectively. There is no cold intolerance. The overall functional result is satisfactory. Replantation of an amputated digit that is properly cooled immediately after injury should be attempted in selected patients even after prolonged ischemia time.

Adult↗
PubMed1987

Simultaneous determination of gastrodin and its metabolite by HPLC.

A rapid and specific HPLC method for the simultaneous determination of gastrodin and its metabolite gastrodigenin (p-hydroxybenzyl alcohol) in rat plasma, bile, liver, urine and faeces is described. The separation was achieved by using a reversed phase column (YWG-C18) eluted with methanol-water (2.5:97.5 v/v). Phloroglucinolum was used as internal standard and the peaks were detected at UV 221 nm. The protein precipitation with ethanol was a very simple and rapid method for sample preparation. The gastrodin and gastrodigenin were quantitated by measuring the peak-height ratios. There was a linear concentration range of 10-320 micrograms/mL in the assay for both compounds. The coefficients of variation (within-day) for samples spiked with gastrodin and gastrodigenin were 2.94% and 3.08%, respectively. The method demonstrated a high specificity and was suitable for use in pharmacokinetic studies.

Animals↗
PubMed1987

On the solution of equations for feel-better hemodialysis.

In this paper, a scheme for "feel better" or optimal hemodialysis (OPTHD) based on a two-compartmental model has been proposed. Contrary to the conventional constant blood flow dialysis (CVTHD), this scheme suggests that the blood flow rate should vary in stages in order to avoid or minimize the disequilibrium syndromes during dialysis. A set of equations for computing the intracellular and extracellular solute concentrations during the OPTHD operation is developed and the computed results are illustrated. Comparing to the CVTHD, the OPTHD has the advantages of operating at a lower and smoother solute concentration difference between compartments for the same length of dialysis time, or it may achieve the same specific degree of blood cleansing within a shorter period of dialysis time.

Computer Simulation↗
PubMedDate not supplied

Osteoblastic cell attachment to hydroxyapatite-coated implant surfaces in vitro.

Hydroxyapatite (HA) used as a coating for implants can exhibit varying levels of interaction with the biologic environment. The crystallinity of the HA-based coating has been shown to control the rate of dissolution and appears to play a role in the initial cellular interaction with the implant surfaces. An osteoblastic cell attachment assay was employed to examine the cell attachment to untreated and pretreated (pH 5.2, 24 hours) titanium and HA coatings of low (50%), medium (75%), and high (90%) crystallinity. A slightly higher percentage of cell attachment (%CA) was found on untreated and pretreated HA surfaces as compared to the titanium surface. No significant difference could be found in the %CA between the 3 levels of crystallinity. However, higher levels of %CA were observed on pretreated HA surfaces than on untreated HA surfaces (t test, P < .05). Elevated calcium and phosphate levels in culture medium did not have any effect on cell attachment. Scanning electron microscopic examinations revealed surface degradation of the HA coating following pretreatment in the simulated inflammatory media (pH 5.2, 24 hours). The results suggest that the altered surface topography may influence the initial cell attachment to HA surfaces.

Analysis of Variance↗
PubMedDate not supplied

Statistical and parametric analysis of beta-2-microglobulin removal from uremic patients in high flux hemodialysis.

Beta-2-microglobulin (beta 2M) associated amyloidosis has been seen in patients with chronic renal failure after long-term hemodialysis. However, the exact mechanism of beta 2M formation and accumulation is not clinically understood. In this investigation, the formation and removal kinetics of beta 2M were studied by compartmental modeling of a patient dialyzer system. Statistical and parametric analyses of model equations, coupled with clinical data from selected patients, enabled us to predict the behavior and influence of membrane materials upon the clearance characteristics of beta 2M during and between hemodialysis treatments.

Acrylonitrile↗
PubMedDate not supplied

The distribution of lifetime cumulative exposures to radon for California residents.

The distribution of individual lifetime exposures to radon was estimated using data from studies on radon concentrations, mobility, and time-activity patterns in the state of California. The distributions of radon concentrations in various geographic regions were obtained from the results of year-long radon measurements of 310 residences. The mobility patterns were acquired through a survey of the moving histories of the members of 507 households. The indoor and outdoor time-activity data were collected for 1,780 individuals in 1,596 households. Based on these data, a computer simulation technique was used to estimate the distribution of radon exposures with a parametric (lognormal model) and a nonparametric approach (bootstrap method). The estimated average lifetime exposure for radon was 2,448 Bq.m-3.yr for the lognormal model and 2,487 Bq.m-3.yr for the bootstrap method. The standard deviation was 1,130 and 1,145 Bq.m-3.yr respectively. Assuming no move over the lifetime, the estimated average lifetime exposure to radon was 2,052 Bq.m-3.yr for the lognormal model and 2,078 Bq.m-3.yr for the bootstrap method, while the standard deviation increased to 1,378 Bq.m-3.yr for the lognormal model and 1,514 Bq.m-3.yr for the bootstrap method.

Adolescent↗