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Biomedical subjects

C W Chang

Publications and source records attributed to C W Chang.

120 records · Page 7Linked to original sources
PubMed1966

Site of fluoride accumulation in navel orange leaves.

Fluoride-polluted navel orange leaves, Citrus sinensis (Linn.) Osbeck, were fractionated into the subcellular components in hexane/carbon tetrachloride mixtures having various densities. Fluoride was determined at each fraction. Analyses were also made for the subcellular distribution of chlorophyll, nitrogen, and DNA to assess the extent of cross-contamination of each component. The fraction containing cell wall, nuclei, and partly broken cells apparently contained a major amount of fluoride. However, if allowance was made for the cross-contamination of chloroplasts and chloroplast fragments, the fraction of chloroplasts was found to be the site of the highest fluoride accumulation. When each particulate component was washed with water after drying, the combined washings contained more than 50% of the total fluoride of the isolated fractions. The usual method of subcellular fractionation with aqueous solvent shifted the major site of fluoride accumulation from the fraction of chloroplasts to that of the supernatant.

Chloroplasts↗
PubMedDate not supplied

Efficacy of preoperative dual-phase sestamibi scanning in hyperparathyroidism.

PURPOSE: The objective of this article is to evaluate our experience with sestamibi scanning in patients with primary and secondary hyperparathyroidism. PATIENTS AND METHODS: A retrospective review of patients referred to the radiology department at the University of Kansas Medical Center for parathyroid studies between January 1, 1993, and August 1, 1998, was done. Patients included in the study were those who underwent both dual-phase technetium (Tc-99m) sestamibi scanning and subsequent parathyroidectomy at our institution (n = 34). Twenty-six patients had primary hyperparathyroidism and 8 patients had secondary hyperparathyroidism. Fifteen had previous history of neck exploration. RESULTS: Sensitivity of sestamibi scans in detection of all abnormal pathology in cases of primary hyperparathyroidism was 60% overall. Among the subset of adenoma cases, sensitivity was 82% (14/17). Among cases of primary parathyroid hyperplasia, no scan correctly localized all abnormal glands; however 60% (3/5) showed localization of at least one hyperplastic gland. Of the 2 patients with parathyroid carcinoma, in only one case was there evidence of sestamibi retention in the correct thyroid lobe. In patients with secondary hyperparathyroidism, sestamibi scanning was successful in identifying all hyperplastic tissue in only one case (sensitivity 13%). In 7 of the 8 cases of secondary hyperparathyroidism, the scan localized at least one hyperplastic gland. CONCLUSION: Sestamibi scanning is useful in the localization of abnormal pathology in cases of primary hyperparathyroidism, especially adenomas. In cases of hyperplasia, whether attributable to primary or secondary hyperparathyroidism, sestamibi imaging is less successful.

Adult↗
PubMedDate not supplied

Lip lead as an alternative measure for lead exposure assessment of lead battery assembly workers.

This study investigated lead exposures of lead battery assembly workers in Taiwan. A special attempt was made to evaluate the use of lip lead as an alternative index for occupational lead exposure. Ninety-six of 113 workers from a lead battery plant were recruited as study subjects. Air lead; lead loadings on workers' sleeves, gloves, hands, cheeks, and lips; and blood lead were determined for exposure assessment. A questionnaire also was administered to collect information on work history, suspected exogenous lead sources, and personal behavior and activities. Geometric means of total air lead at different subareas ranged from 0.070 (2.5 geometric standard deviation [GSD]) to 0.159 (1.8 GSD) mg/m3. Geometric means of respirable air lead level for different subgroups of workers varied from 0.009 (2.0 GSD) to 0.032 (1.9 GSD) mg/m3, whereas those of the blood lead level ranged from 22.4 (1.3 GSD) to 44.5 (1.3 GSD) microg/dL. The heaviest lead loadings were found for plate-processing workers (e.g., 66.4 [1.5 GSD] on gloves, 0.80 [3.7 GSD] on cheeks, and 0.79 [3.2 GSD] microg/cm2) on bare-hands after washing. Blood lead level was significantly correlated with lead levels in air, lead loadings on lips, and bare hands after washing (r=0.24-0.30). Results of multiple regression analysis showed that only lip lead had a significant effect on the blood lead, whereas respirable air lead and personal behavior had only mild effects in this model. It was concluded that lip lead level may be used as an alternative index of lead exposure to facilitate the estimation of lead uptake through ingestion.

Cheek↗
PubMedDate not supplied

Tardy effect of neurogenic muscular atrophy by magnetic stimulation.

The influence of pulsed magnetic stimulation on denervated muscles was investigated in this study. Of 24 rats divided into three groups for experiment, 8 rats served as control; 16 rats with bilaterally severed sciatic nerves were divided into two groups for different modes of stimulation. Magnetic stimulation with a high power output that induced an intensive contraction of muscle was applied at one side-denervated gastrocnemius muscle for 1 mo in a group of rats; electric stimulation with high intensity at 6 Hz frequency and 1-ms pulse duration served as a contrast in the other group. Muscular weight, volume, fiber diameter and percentage of fiber types were measured after the experiment. A significant retardation of weight loss in denervated muscles via magnetic stimulation (P < 0.05) was confirmed by observed results. Type II fiber atrophy was retarded in denervated muscles by magnetic stimulation as well as in denervated muscles via electric stimulation. Magnetic stimulation, used as a method that induces muscular activity, was verified in this study as being capable of retarding denervated muscular atrophy. Its benefits of painless stimulation as well as deeply activated muscular contraction could be expected to function as a new model for rehabilitation of paralyzed muscles.

Animals↗
PubMedDate not supplied

Absence of human herpesvirus-6 genome by polymerase chain reaction in children with Hodgkin disease: a Children's Cancer Group Lymphoma Biology Study.

BACKGROUND: Human herpesvirus-6 (HHV6) has been implicated in adult lymphomas but the role that HHV6 has in lymphomagenesis is unclear. Because primary infection occurs in children, a prospective study was undertaken to detect HHV6 in those with pediatric Hodgkin disease (HD). OBSERVATIONS: Tumor was obtained from children with HD entered on a Children's Cancer Group Biology Study. Polymerase chain reaction (PCR) was performed using HHV6 primers. All 47 specimens (40 nodular sclerosing; 3 lymphocyte predominant; 3 mixed cellularity; and 1 unclassified) were negative for HHV6. CONCLUSIONS: The results demonstrate no HHV6 sequence in childhood HD.

Child↗
PubMedDate not supplied

Estimation of normal motor conduction velocity of spinal cord by using transcranial electric stimulation and F-wave study.

A non-invasive method for estimation of motor conduction velocity of the spinal cord was performed by transcranial electric stimulation of motor cortex and an F-wave study of the peripheral nerve. Fourty normal persons including 24 men and 16 women ranging in age from 24 to 55 years (mean, 32 years) participated in the study. With a transcortical electric stimulation over the motor cortex, both the conduction time to the contralateral abductor pollicis brevis and the anterior tibial muscles, and the amplitude of the muscle action potentials were recorded. F-wave studies were performed in the median and peroneal nerves. Motor spinal cord conduction velocity (SCCV) was calculated by measuring the distance from 7th cervical to 12th thoracic spinal processes and dividing by the central conduction time obtained by the motor evoked potential studies and the F-wave latencies. The results showed a motor SCCV of 63.3 +/- 8.6 (mean +/- 1 SD) m/sec in all subjects. There was no difference in male and female groups. The conduction time from the motor cortex to the target muscles was not different in both sex groups correlating to the factor of body height. From these results the conclusion was made that the estimation of motor SCCV is measurable and provides valuable data in the detection of electrophysiological function of spinal motor pathways.

Action Potentials↗
PubMedDate not supplied

Correlation of HbA1c concentration and single-fiber EMG findings in diabetic neuropathy.

Plasma-glycosylated hemoglobin (HbA1c), i.e., an indicator of metabolic control in diabetic patients, was measured and correlated with neuromuscular jitter and fiber density, which were obtained by single-fiber (SF) EMG assessment. Of the 112 diabetic patients who participated in this study, 34 clinically non-neuropathic patients were categorized in group III, and 78 patients with diagnosed clinical neuropathy were divided into groups I and II, with electrophysiological neuropathy and non-neuropathy, respectively, according to the measurements of nerve conduction. All patients received SFEMG tests and second verifications of levels of HbA1c. In group I (46 patients) and group II (32 patients), the levels of HbA1c were positively correlated with neuromuscular jitters and fiber densities; whereas, no correlation occurred in group III patients. SFEMG findings in diabetic patients provide a higher sensitivity in detecting diabetic neuropathy as compared to nerve conduction studies. The regression for correlation of HbA1c levels and SFEMG findings indicated that axonal degeneration and reinnervation processes with instability of neuromuscular junction in diabetic neuropathy are consistent with the metabolic control of this disease.

Adult↗
PubMedDate not supplied

Evident transsynaptic degeneration of motor neurons after spinal cord injury: a study of neuromuscular jitter by axonal microstimulation.

Neuronal degradation accompanied with axonal degeneration has been known to occur in spinal motor neurons after an upper level of spinal cord lesion. In the present study, the functional integrity of neuromuscular transmission was assessed by utilizing a sensitive electrodiagnostic method comprising of stimulated single-fiber electromyography (SFEMG), along with axonal microstimulation, in paralytic muscles of patients with spinal cord injury (SCI). Neuromuscular jitter was measured in anterior tibial muscles for 30 patients with SCI and also for 12 normal controls. Mean jitter of 37.4 +/- 14.7 (mean +/- SD) micros, as obtained in SCI patients, was found to be significantly greater than the results of 20.1 +/- 8.4 micros in normal controls (P < 0.01). Jitter measurement was not significantly different in varied functional scales of SCI. A positive correlation was noted between the increased jitter and the disease duration from the onset of cord lesion till the time of stimulated SFEMG test (r = 0.68; P < 0.01). The present abnormal finding of neuromuscular jitter provides an electrophysiologic evidence for axonal degeneration and suggests that transsynaptic degeneration of motor neuron may occur below the level of cord lesion in SCI patients. Furthermore, the neuronal degradation in SCI was positively correlated with the course duration of the disease.

Adolescent↗