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Biomedical subjects

H H Chang

Publications and source records attributed to H H Chang.

At least 55 records · Page 3Linked to original sources
PubMed1994

Familial visceral neuropathy as part of a diffuse neuronal syndrome: four fatal cases in one sibship.

Familial visceral neuropathy is a rare cause of chronic intestinal pseudo-obstruction. It is characterized by progressive destruction of the gastrointestinal myenteric plexus resulting in dysmotility and associated early satiety, post-prandial bloating, recurrent nausea and vomiting, abdominal distension, chronic diarrhea, weight loss, and malnutrition. In its varying forms, there may be neuronal destruction in other parts of the peripheral and central nervous system. We report on four siblings who presented in their third or fourth decades with initial clinical features of chronic intestinal pseudo-obstruction and eventual progressive diffuse neuronal disease, characterized by leukoencephalopathy and peripheral neuropathy. Within 5 yr of presentation, all four patients died from inanition and sepsis, despite aggressive nutritional support. Their clinical and pathological features are characteristic of familial visceral neuropathy of the autosomal recessive form. This presentation may represent a unique syndrome characterized by a tetrad of polyneuropathy, ophthalmoplegia, leukoencephalopathy, and intestinal pseudo-obstruction.

Adult↗
PubMed1993

Rhodostomin, an RGD-containing peptide expressed from a synthetic gene in Escherichia coli, facilitates the attachment of human hepatoma cells.

Rhodostomin (Rho) from snake venom, a potent inhibitor of platelet aggregation, contains 68 amino acids having an RGD sequence and 12 cysteine residues. A chemically synthesized Rho gene was cloned and expressed in Escherichia coli. The expression of Rho gene fused with the glutathione S-transferase (GST) gene was about 10-30% of total cell proteins. The Rho-fusion protein could be recognized by antibodies raised against either a native Rho peptide or a synthetic peptide. The purified GST-Rho coated on culture plates facilitated the attachment of human hepatoma cells, which was inhibitable by co-incubation with a synthetic hexapeptide GRGDSP but not with a related peptide of GRGESP, suggesting that the E. coli-expressed Rho-fusion protein was properly folded and biologically functional.

Amino Acid Sequence↗
PubMed1993

Agrobacterium-mediated production of transgenic rice plants expressing a chimeric alpha-amylase promoter/beta-glucuronidase gene.

We have successfully transferred and expressed a reporter gene driven by an alpha-amylase promoter in a japonica type of rice (Oryza sativa L. cv. Tainung 62) using the Agrobacterium-mediated gene transfer system. Immature rice embryos (10-12 days after anthesis) were infected with an Agrobacterium strain carrying a plasmid containing chimeric genes of beta-glucuronidase (uidA) and neomycin phosphotransferase (nptII). Co-incubation of potato suspension culture (PSC) with the Agrobacterium inoculum significantly improved the transformation efficiency of rice. The uidA and nptII genes, which are under the control of promoters of a rice alpha-amylase gene (alpha Amy8) and Agrobacterium nopaline synthase gene (nos), respectively, were both expressed in G418-resistant calli and transgenic plants. Integration of foreign genes into the genomes of transgenic plants was confirmed by Southern blot analysis. Histochemical localization of GUS activity in one transgenic plant (R0) revealed that the rice alpha-amylase promoter functions in all cell types of the mature leaves, stems, sheaths and roots, but not in the very young leaves. This transgenic plant grew more slowly and produced less seeds than the wild-type plant, but its R1 and R2 progenies grew normally and produced as much seeds as the wild-type plant. Inheritance of foreign genes to the progenies was also confirmed by Southern blot analysis. These data demonstrate successful gene transfer and sexual inheritance of the chimeric genes.

Agrobacterium tumefaciens↗
PubMed1993

Identification and characterization of epitopes on Cyn d I, the major allergen of Bermuda grass pollen.

BACKGROUND: We identified three epitopes on Cyn d I by using four anti-Cyn d I monoclonal antibodies (MoAbs). METHODS: In a cross-inhibition binding assay, the binding of MoAbs 1-61 and 10-7 to Cyn d I was completely blocked by each other but not by MoAbs 4-37 and 11-7; the binding of MoAb 4-37 and MoAb 11-7 to Cyn d I was inhibited by themselves but not by other MoAbs. The epitope recognized by MoAbs 1-61 and 10-7 is designated as E1, and those recognized by MoAbs 4-37 and 11-7 are designated as E2 and E3, respectively. RESULTS: In a radioallergosorbent inhibition assay, we found that MoAbs 1-61 and 4-37 (1:50 diluted) can inhibit the binding of human Immunoglobulin Es to Cyn d I by more than 30%, whereas MoAb 11-7 was less efficient (reduced by only 6%). These results suggest that both E1 and E2 are major allergenic epitopes but that E3 is only a minor one. Further characterization of E1 and E2 reveals that they are labile in alkaline but resistant to acid and sodium periodate treatments. Moreover, E1 is heat-labile, but guanidine- and urea-sensitive, whereas E2 is not. Both E1 and E2 lost their antigenicity after reduction and alkylation. CONCLUSIONS: Results of the present study provide important information on the physicochemical properties of major allergenic epitopes on Cyn d I, which may be useful for future development of therapeutic peptides for patients allergic to Bermuda grass pollen.

Allergens↗
PubMed1993

High frequency of thyroid tumor induction by N-methyl-N'-nitro-N-nitrosoguanidine in the hermaphroditic fish Rivulus marmoratus.

In the self-fertilizing hermaphroditic fish, Rivulus marmoratus, the susceptibility to tumor induction by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was evaluated. Seven-day-old fish larvae were exposed for 2 h to MNNG at concentrations ranging from 5 to 25 ppm in a static water bath. The exposed fish were observed at 2 and 4 months after carcinogen treatment to assess tumor development. Within 4 months after 25 ppm MNNG exposure, nearly all fish developed thyroid tumors. The tumor incidences were dose- and time-dependent, and the latent period of tumor induction was less than 2 months. Most induced neoplasms were papillary carcinomas similar histologically to those of rodents and humans, and the tumors were serially transplantable to other fish of the same species. These results demonstrate that rivulus could be useful as a model of thyroid carcinogenesis.

Animals↗
PubMed1993

Ontogenic differences in the inhibition of gastric acid secretion by epidermal growth factor.

Gastric secretions were studied in rats by pyloric ligation in vivo. The effects of epidermal growth factor (EGF) administered s.c. on gastric secretion were evaluated at different stages of development (8, 14, 20 and 30 postnatal days). The rates of fluid, protein and acid outputs were very low in developing rats but increased in maturing rats. The rate of acid output in 8- day-old rats (3.83 +/- 1.16) was not different from that in 14-day-old rats (4.84 +/- 0.99), whereas the rate of acid output in 20-day-old rats was 11-fold greater than that in 14-day-old rats, and it was 21-fold greater in 30-day-old rats. Subcutaneous administration of 30 micrograms/kg b.wt. of EGF significantly suppressed the gastric secretion of fluid, protein and acid in 20- and 30-day-old rats. In 30-day-old rats, acid output was 85% lower at 1 hr after EGF administration and in 20-day-old rats it was 85% lower at 2 hr and 50% lower at 3 hr. Interestingly, EGF had no effect on basal gastric secretions in 8- and 14-day-old rats; EGF also had no effect on the gastric acid output that was stimulated by pentagastrin administration in 14-day-old rats. In 20-day-old rats, inhibitory effects of EGF lasted for 3 hr before gastric secretions rebounded to normal levels, but inhibition lasted for only 1 hr in 30-day-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1992

Teratogenic effects of N-nitrosodiethylamine in embryos of the hermaphroditic fish Rivulus marmoratus.

Exposure of N-nitrosodiethylamine (NDEA) to hermaphroditic fish (Rivulus marmoratus) embryos induced specific congenital malformations when the chemical was applied to embryos on days 0-6 post morula stage. This sensitive period generally coincided with the known period of organogenesis in this species, and the incidence of anomalies was clearly dose related. These results indicate that NDEA is teratogenic to fish embryos.

Abnormalities, Drug-Induced↗
PubMed1992

Large soft tissue tumor of the chest occurring after trauma.

The unusual soft tissue tumor we have described may be the largest yet reported. The tumor was considered benign, and its histologic features were most consistent with fibromatosis arising in a region that had been previously traumatized. Although the patient is doing well, it is premature (2 years later) to conclude that the tumor will not recur.

Adolescent↗
PubMed1990

Induction of hepatic tumors with butylated hydroxyanisole in the self-fertilizing hermaphroditic fish Rivulus ocellatus marmoratus.

The three-day-old larvae of self-fertilizing hermaphroditic fish Rivulus ocellatus marmoratus were fed a diet containing the antioxidant butylated hydroxyanisole (BHA) at levels of 0.01-0.8% for 12 days. Six months after BHA administration, hepatic tumors were found in all groups of BHA-treated fish. The BHA-induced tumor incidences were clearly dose-dependent. These results show that dietary BHA is hepatocarcinogenic in Rivulus even at 0.01% dose.

Animals↗
PubMed1989

Rapid chromosome analysis with the use of spontaneously dividing cells derived from umbilical cord blood (fetal and neonatal).

An accurate and reproducible method to obtain high-quality metaphases within 24 hours has been developed. Preparations can be derived from cord blood samples obtained either at delivery or by percutaneous umbilical blood sampling. Mitogens are not required. Rapid cytogenetic analysis can facilitate management of pregnancies characterized by malformations or intrauterine growth retardation.

Cell Division↗
PubMed1987

Benign fibrous ureteral polyps.

Benign fibrous polyps of the ureter are rare. A review of the English literature since 1930 revealed that 71 cases had been described. Three additional cases of fibrous ureteral polyps, one in a ureter with ureteritis cystica, are reported with a discussion of both the histologic findings and proposed treatment plan.

Adult↗
PubMed1984

Depolarization-induced release of L-glutamic acid from isolated-resealed synaptic membrane vesicles.

L-Glutamic acid actively loaded into resealed brain synaptic membrane vesicles was rapidly released into the incubation medium following the introduction of KCl and CaCl2, or nigericin, or veratridine into the external medium. The KCl-induced release was enhanced by the presence of low (0.1 mM), extravesicular [Ca2+]. Neither the KCl-induced nor the veratridine-stimulated L-glutamate efflux were carrier-mediated processes. Finally, the KCl-stimulated L-glutamate efflux was dependent on the ratio of intra- to extravesicular [K+]. The observations described in this study were indicative of depolarization-induced L-glutamate release from isolated synaptic plasma membrane vesicles.

Animals↗
PubMed1984

Functional characteristics of L-glutamate, N-methyl-D-aspartate and kainate receptors in isolated brain synaptic membranes.

L-Glutamic acid (L-Glu) and other excitatory amino acids and amino acid analogs enhanced [35S]thiocyanate (SCN-) uptake in isolated-resealed synaptic membrane vesicles. The SCN- uptake was used as a measure of membrane depolarization to evaluate the characteristics of functional excitatory amino acid receptors in the synaptic membranes. N-Methyl-D-aspartate (NMDA) and L-Glu produced additive effects on SCN- accumulation indicating the presence of distinct L-Glu and NMDA receptors. On the other hand, kainic acid (KA) and L-Glu shared either common receptor sites or ion channels. The effects of antagonists on NMDA, L-Glu, and KA stimulation of SCN- influx were consistent with previously reported electrophysiologic observations in intact neurons.

Animals↗
PubMed1984

Effects of amphipathic drugs on L'[3H]glutamate binding to synaptic membranes and the purified binding protein.

Four amphipathic molecules with known local anesthetic activity, dibucaine, tetracaine, chlorpomazine, and quinacrine, inhibited the binding of L-[3H]glutamic acid to rat brain synaptic plasma membranes and to the purified glutamate binding protein. Neither haloperidol nor diphenylhydantoin had significant inhibitory effects on the glutamate binding activity of the membranes or of the purified protein. The amphipathic drugs apparently inhibited L-[3H]glutamate binding to synaptic membranes by a mixed type of inhibition. The inhibitory activity of quinacrine on glutamate binding to the synaptic membranes was greater in a low ionic strength, Ca2+-free buffer medium, than in a physiologic medium (Krebs-Henseleit buffer). Removal of Ca2+ from the Krebs solution enhanced quinacrine's inhibition of glutamate binding. Quinacrine up to 1 mM concentration did not inhibit the high affinity Na+-dependent L-glutamate transport in these membrane preparations. The importance of Ca2+ in the expression of quinacrine's effects on the glutamate binding activity of synaptic membranes and the observed tetracaine and chlorpromazine-induced increases in the transition temperature for the glutamate binding process of these membranes, were indicative of an interaction of the local anesthetics with the lipid environment of the glutamate binding sites.

Anesthetics, Local↗
PubMed1984

Primary mediastinal choriocarcinoma in a man with an abnormal chromosome.

We have described a case of primary choriocarcinoma of the mediastinum and reported the results of electron microscopic and immunohistochemical studies. In the past, the prognosis of this tumor was poor, despite aggressive chemotherapy. Results of the recently developed protocol using intensive therapy with cisplatin-containing agents are promising.

Adult↗