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Biomedical subjects

Y C Chang

Publications and source records attributed to Y C Chang.

At least 325 records · Page 18Linked to original sources
PubMed1988

Identification of the two cell groups in the longitudinal muscle layer of the earthworm Amynthas hawayanus by a single microelectrode with lucifer yellow-CH.

Previous electrophysiological studies have suggested the presence of two types of muscular cells in the longitudinal muscle of A. hawayanus. However, a definite classification of such cells as muscles has been hindered by lack of morphological evidence. This study identified these cells electrophysiologically and morphologically by using the same intracellular microelectrode to record cell activity and inject Lucifer Yellow-CH. Electrophysiological measurements clearly differentiated the two groups of cells. One group did not respond to nerve stimulation but was spontaneously active, whereas the other responded to nerve stimulation with endplate potentials and did not discharge spontaneously. Morphological examination revealed two very similar types of longitudinal muscle cells. These results clearly show that, although morphologically similar, there are two distinct groups of muscle cells in the longitudinal muscle layer of the earthworm.

Animals↗
PubMed1988

Lucifer yellow-CH identification of a primary neuron connecting the first segmental nerve to the three giant axons in the nerve cord of the earthworm Amynthas hawayanus.

This is the first step in the identification of a primary or first-order neuron connecting terminal organs, such as receptors or muscle, to interneurons, such as giant axons. The preparation employed here was a single segment of the ventral nerve cord between the 30th and the 40th segment, with a single first segmental nerve connected. A small drop of 7% Lucifer Yellow-CH was placed at the cut end of the first nerve in the absence of detergent or electric current. A structured complex could be seen in the cord anterior to the first nerve after one or two min backfilling. Several long processes extend from this structure to the contralateral side of the nerve cord and terminate in button-like structures near the medial giant axon and the contralateral lateral giant axon. The afferent or efferent function of this neural complex remains to be determined.

Animals↗
PubMed1988

A rhythmically discharging neuron in the earthworm ventral cord nerve as identified by lucifer yellow-CH injection.

In the process of mapping the ganglionic neurons in the earthworm ventral nerve cord by simultaneous recording and Lucifer Yellow-CH injection or by backfilling, a rhythmically discharging neuron with a continuous train of 100 cps over the entire recording period was encountered at the dorsal side of the cord near the base of the 2nd-3rd nerves, with its axon extending toward the 2nd-3rd contralateral nerves. It could not be determined whether branches of this axon entered these contralateral nerves. The rhythmic discharge could not be recorded extracellularly from the nerves or from the cord by suction or hook electrodes, nor did the cell respond to either intra- or extracellular stimulation through the recording and injection microelectrode. Although contralateral neurons have been described in histological works, this neuron may not be identifiable one of them until its relationship with other neurons becomes clear.

Animals↗
PubMed1988

Responses to electrical and mechanical stimuli of the epithelium in earthworm giant axons identified by lucifer yellow-CH dye.

The present study shows a correlation between the evoked response and the cell where the response was recorded. The cells in question are the three giant axons, one median giant fiber (MGF) and two lateral giant fibers (LGF), and the responses were evoked by electrical and mechanical stimuli applied to the epithelial surface of an isolated neuromuscular preparation from the earthworm, Amynthas hawayanus. Extra- and intracellular responses were recorded from the ventral nerve cord and from the three giant axons. Lucifer Yellow-CH was injected into the axon simultaneously while recording intracellularly with a Dagan 8,500 high impedance bridge system. The action potentials thus evoked were conducted antero-posteriorly and postero-anteriorly in both types of giant axons. Different latencies were found between the electrically and the mechanically evoked responses and between the responses recorded from the MGF and from the LGF. These differences may be attributed to different neuronal circuits conveying these responses to both giant axons.

Animals↗
PubMed1988

Characterization of the proteins purified with monoclonal antibodies to glutamic acid decarboxylase.

Immunoaffinity columns are prepared from the monoclonal antibody (MAb) GAD-1. These columns are used to enrich glutamic acid decarboxylase (GAD) from the cytosolic fraction of rat brain homogenates and from Triton X-100 extracts of the brain membrane fraction. In each case enzyme activity is enriched over 400-fold. The immunopurified fractions were analyzed by SDS-PAGE. Fractions purified from the cytosol consisted of a quantitatively major band of 59 kDa, and one band of 63 kDa, as well as a group centered around 55 kDa. Fractions purified from membranes consisted primarily of the 59 and 63 kDa components; only traces of the lower-molecular-weight components were present. The entire set of proteins purified on GAD-1 immunoaffinity columns is strongly recognized by 2 widely used antisera to GAD, those described in Saito et al. (1974) and Oertel et al. (1981). The 59 kDa protein from the cytosolic fraction was purified to homogeneity by preparative SDS-PAGE; a partial amino acid sequence of this protein was obtained. The 59 kDa protein has a high degree of sequence homology with the deduced amino acid sequence of the protein that was coded for by a cDNA for feline GAD (Kaufman et al., 1986; Kobayashi et al., 1987). Thus, these proteins are either products of a single gene that diverged during the evolution of rat and cat from a common ancestor, or are members of a closely related set of genes found in both species. The MAb GAD-6 recognizes the 59 kDa band and the group of bands centered around 55 kDa on Western blots. Therefore, these proteins are immunochemically related. GAD-6 does not recognize the 63 kDa band. In Western blots of unfractionated homogenates of the whole brain, the only band recognized by GAD-6 is a 59 kDa band.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1987

Function of pyridoxal 5'-phosphate in glycogen phosphorylase: a model study using 6-fluoro-5'-deoxypyridoxal- and 5'-deoxypyridoxal-reconstituted enzymes.

A new vitamin B6 analogue, 6-fluoro-5'-deoxypyridoxal (6-FDPL), was synthesized and characterized. This analogue, as well as 6-fluoropyridoxal (6-FPAL), 6-fluoropyridoxal phosphate (6-FPLP), and 6-fluoropyridoxine, showed positive heteronuclear 1H-19F nuclear Overhauser effects between the 5'-protons and the 6-fluorine. Apophosphorylase reconstituted with 6-FDPL showed 1% of the activity of the native enzyme in the presence of phosphite. The kinetic pattern, apparent pH optimum of activity, and the activity-temperature dependency of the 6-FDPL-enzyme were virtually identical with those of phosphorylase reconstituted with the parent compound, 6-FPAL [Chang, Y. C., & Graves, D. J. (1985) J. Biol. Chem. 260, 2709-2714], except the Km of phosphite toward the 6-FDPL-enzyme was 9 times higher than that with the 6-FPAL-enzyme and the 6-FDPL-enzyme showed a lower Vmax value. Phosphorylase reconstituted with 5'-deoxypyridoxal (DPL) also showed activity in the presence of phosphite. The kinetics and the temperature-activity dependency of this reconstituted enzyme were investigated. 19F nuclear magnetic resonance studies showed that the binding of glucose 1-phosphate to a 6-FDPL-enzyme-adenosine 5'-phosphate (AMP) complex shifted the 19F signal 0.6 ppm upfield, whereas a 2.1 ppm change was observed when the 6-FPAL-enzyme-AMP formed a complex with glucose 1-phosphate [Chang, Y. C., Scott, R. D., & Graves, D. J. (1986) Biochemistry 25, 1932-1939].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Appraisal of hepatic resection in the treatment of minute hepatocellular carcinoma associated with liver cirrhosis.

During the last 6 years, 205 patients with primary hepatocellular carcinoma (HCC) were admitted to our surgical departments. Thirty-eight had HCC smaller than 3 cm in diameter. There were 34 men and 4 women with an average age of 56.5 years. All patients had underlying hepatic disease: liver cirrhosis in 35 patients and chronic active hepatitis with fibrosis in the remaining 3. Pre-operative complications included: oesophageal varices in ten, cholelithiasis in five, peptic ulcer in two, gastric cancer in one, and severe hypersplenism in one instance. A radical resection was performed in 32 cases and palliative resection in 6. Simultaneous operations were carried out for the above mentioned associated conditions: distal splenorenal shunt in six, Hassab's devascularization procedure in one, splenectomy in one, cholecystectomy in four, cholecystolithotomy in one, and partial gastrectomy in one. Four patients had postoperative complications: liver failure, rebleeding, right haemothorax, and upper gastrointestinal bleeding from acute mucosal lesion of the stomach. One patient with liver failure died in coma within 1 month. The operative and in-hospital mortality rates were 2.6 and 7.9 per cent, respectively. Survival rates during the first 4 years in 32 patients with radical hepatic resection were 89.9, 67.2, 58.8, and 58.8 per cent, respectively. We suggest that hepatic resection should be the first choice of treatment for minute HCC even in the presence of liver cirrhosis.

Adult↗
PubMed1987

Angiosarcoma of the bladder: a case report.

We report a case of angiosarcoma of the bladder. Numerous cases of hemangioma of the bladder have been reported previously but only 3 cases of angiosarcoma have been published. In our case immunoperoxidase staining for factor VIII antigen was useful in substantiating the diagnosis of angiosarcoma.

Aged↗
PubMed1987

Neurotoxic effects of n-hexane on the human central nervous system: evoked potential abnormalities in n-hexane polyneuropathy.

An outbreak of n-hexane polyneuropathy as a result of industrial exposure occurred in printing factories in Taipei area from December 1983 to February 1985. Multimodality evoked potentials study was performed on 22 of the polyneuropathy cases, five of the subclinical cases, and seven of the unaffected workers. The absolute and interpeak latencies of patterned visual evoked potential (pVEP) in both the polyneuropathy and subclinical groups were longer than in the normal controls. The pVEP interpeak amplitude was also decreased in the polyneuropathy cases. Brainstem auditory evoked potentials (BAEP), showed no difference of wave I latency between factory workers and normal controls, but prolongation of the wave I-V interpeak latencies was noted, corresponding with the severity of the polyneuropathy. In somatosensory evoked potentials (SEPs), both the absolute latencies and central conduction time (CCT) were longer in subclinical and polyneuropathy cases than in the unaffected workers and normal controls. From this evoked potentials study, chronic toxic effects of n-hexane on the central nervous system were shown.

Adolescent↗
PubMed1987

Clinical comparison between original and modified distal splenorenal shunts.

This article reports on a retrospective clinical comparison between the original Warren shunt and one that we modified with Gore-Tex (expanded polytetrafluoroethylene) interposition. The former operation was performed on 35 patients between June 1969 and November 1983 and the latter on 29 patients between October 1983 and January 1986. There were no significant differences in the patients' backgrounds between the two study groups. Blood loss during surgery was significantly greater and operation time was longer in the original shunt group than in the modified shunt group. The incidence of postoperative morbidity and mortality was also significantly higher in the former group than in the latter (major complication rate: 20.0% versus 3.4%; operative death within 1 month: 5.7% versus 0%; in-hospital death: 11.4% versus 3.4%). The modified shunts had a 100% patency rate, and no variceal bleeding was evident, whereas shunt occlusion was observed in two patients and portal thrombosis in one patient of the original shunt group. The incidence of hepatic encephalopathy was 14.3% in the original shunt group and 6.9% in the modified shunt group, and the follow-up time was shorter in the latter group. A significantly greater rate of survival was achieved with the modified Warren shunts. Thus the current study seems to indicate that our modifications could be alternatives to the original distal splenorenal shunt in terms of postoperative morbidity, mortality, and survival.

Adult↗
PubMed1986

Identification of an enzymatic activity that hydrolyzes protein-bound ADP-ribose in skeletal muscle.

An enzymatic activity present in high-speed supernatant fluids of rat skeletal muscle was found that catalyzes the release of ADP-ribose from ADP-ribosylated-modified lysozyme. The nature of the product was proved by chromatographic studies and proton nuclear magnetic resonance spectroscopy. The enzyme activity is stimulated by Mg2+, dithioerythritol, and flouride. These results and those published earlier (Soman, G., Mickelson, J.R., Louis, C.F., and Graves, D.J. (1984) Biochem. Biophys. Res. Commun. 120, 973-980) show that ADP-ribosylation is a reversible process in skeletal muscle.

Adenosine Diphosphate Ribose↗
PubMed1986

Active uptake of testosterone by androgen receptors of hepatocellular carcinoma in humans.

Hepatocellular carcinoma (HCC) is more prevalent in males than it is in females, which has often been explained by the fact that alcoholism and chronic hepatitis B virus infection are more prevalent among males. The current studies, using biochemical and autoradiographic methods, verified that HCC contains higher concentrations of androgen receptors than the surrounding liver parenchyma and that extrinsically given testosterone are actively taken up by such tumors. These results may suggest that HCC is an androgen-dependent tumor and that, therefore, this tumor is more prevalent in males than it is in females.

Autoradiography↗