PubMed Health⌕ Search

Biomedical subjects

L Y Cheng

Publications and source records attributed to L Y Cheng.

53 records · Page 3Linked to original sources
PubMed1983

The withdrawal of benztropine mesylate in chronic schizophrenic patients.

In this double-blind, four-week study, 28 chronic schizophrenic patients receiving neuroleptic medication plus the antiparkinsonian drug, benztropine mesylate, were either switched to placebo or maintained on benztropine. Patients withdrawn from benztropine reliably increased their overall scores on the Wechsler Memory Scale in comparison with the drug group. Sub-test scores suggest that deficits in attention and concentration were induced by treatment with benztropine. Psychotic decompensation appeared to develop simultaneously with extrapyramidal symptoms (EPS) in some patients, but only 14.2 per cent of the placebo group experienced extrapyramidal symptoms severe enough to require resumption of benztropine therapy. It is suggested that antiparkinsonian agents should be prescribed only if and when EPS occur.

Adolescent↗
PubMed1982

Chemical modification of hemoglobin in intact whole cells: morphological studies by scanning electron microscope.

1. Whole blood was incubated in physiological conditions with a variety of modifiers capable of modifying hemoglobin. Some of these compounds have been considered as therapeutic agents for certain hemoglobinopathies such as sickle-cell disease. 2. The extent of modification on hemoglobin was estimated by electrophoresis and the red-cell morphology by scanning electron microscope. 3. Results indicated that carbamyl phosphate, aspirin and glutaryl-salicylamide had no observable effect, whereas cross-linkers in general produced drastic changes in red-cell morphology. 4. Dibromoaspirin, a very effective acetylating agent, produced abnormalities even in concentrations as low as 1 mM.

Anemia, Sickle Cell↗
PubMed1979

Chemical cross-linking of hemoglobin H. A possible approach to introduce cooperativity and modification of its oxygen transport properties.

Native and reconstituted hemoglobin H molecules were cross-linked with glutaraldehyde at pH values close to the physiological. The Schiff base adducts were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis before and after reduction with sodium borohydride. The major component had a molecular weight of about 31 000 which corresponded to the dimeric species of the beta subunit. In contrast to the native protein, which has very high oxygen affinity and no heme-heme interaction or 2,3-diphosphoglyceric acid effect, the modified hemoglobin H molecules showed cooperative oxygen binding, decreased oxygen affinity and a noticeable 2,3-diphosphoglyceric acid effect.

Biological Transport↗
PubMedDate not supplied

Quantitative electrophoretic study of the modification of sperm plasma membrane by the ampullary gland in the golden hamster.

Plasma membrane proteins were extracted either from epididymal sperm after incubation with ampullary gland secretion or from uterine sperm derived from surgically treated males belonging to the following groups: TX, excision of all accessory sex glands (ASG); AGX, bilateral excision of ampullary glands; AG, excision of all ASG except ampullary glands; and SH, sham-operated. Total membrane protein, glycoprotein, and SDS-PAGE of individual polypeptide subunits were quantified. After incubation with ampullary gland secretion, both protein and glycoprotein concentrations of epididymal sperm membrane were increased. The protein profile was also significantly altered, with the removal of the 43- and 71-kD subunits and the addition of the 36- and 50-kD subunits. The in vitro results confirmed this proteolytic effect of ampullary gland and other ASG on the 43- and 71-kD subunits, despite a reduction in membrane protein concentration. Modification of the 17-, 20-, 25-, 28-, 56-, and 66-kD proteins were also observed. This report is the first demonstration that the ampullary gland is capable of modifying proteins on the sperm surface.

Animals↗
PubMedDate not supplied

Electrophoretic modification of sperm plasma membrane by ventral prostate secretion in golden hamsters.

Plasma membrane proteins were extracted either from epididymal spermatozoa after incubation with ventral prostate gland secretion or from spermatozoa recovered from uteri of females mated with surgically treated males belonging to the following groups: TX (excision of all accessory sex glands, ASG), VPX (bilateral excision of ventral prostate), VP (bilateral excision of all ASG except the ventral prostate), and SH (sham-operated). Incubation of spermatozoa with ventral prostatic secretion resulted in an 11-fold increase in glycoprotein content of the plasma membrane, but total protein concentration remained unchanged. The in vivo study indicated that interactions of ASG secretions and spermatozoa were complicated by the presence of uterine secretions. Glycoprotein content was reduced in the presence of ventral prostatic secretions. SDS-PAGE profiles showed that both uterine and ASG secretions could modify proteins on the sperm surface. Enrichment of a 25-kD subunit was apparently effected by uterine secretions and further promoted by combined secretions of the ampullary gland, coagulating gland, dorsolateral prostate, and seminal vesicle, but was reduced by the ventral prostate. A number of other protein subunits appeared to be specifically modified by the ventral prostate, while other ASG secretions were also shown to alter the effects of the ventral prostate on the sperm surface.

Animals↗
PubMedDate not supplied

Modulation of EGF receptor by tumor necrosis factor-alpha in human hepatocellular carcinoma HepG2 cells.

TNF alpha is known to exert multi-regulatory effects on normal and malignant cell functions by binding to the corresponding cell surface receptor. However, the existence of cross interaction between TNF alpha and EGF receptor has been proposed. In this study, we investigated the modulatory effect of TNF alpha on EGF receptor of a human hepatocellular carcinoma cell line-HepG2. The results suggested that TNF alpha was able to modulate the EGF receptor of HepG2 cells. The modulatory effect of TNF alpha on the EGF receptor of HepG2 cells exhibited its unique characteristics in comparison with the previous reports on other tumor cells. TNF alpha could also enhance the tyrosine phosphorylation of the EGF receptor of HepG2 cells. However, the effect appeared only if EGF was present, and was not mediated by TNF alpha alone. Therefore, the effect of TNF alpha on EGF receptor tyrosine phosphorylation in HepG2 cells was due to enhancing the receptor's response to EGF. TNF alpha was also able to reduce the affinity of the high-affinity receptor for EGF. However, there was no significant alteration in terms of the expression of EGF receptor, EGF internalization, or EGF degradation when HepG2 cells were treated with TNF alpha. Since TNF alpha is an inhibitory agent for HepG2 cell growth, this cross interaction between TNF alpha and EGF receptor may play a role in the inhibition of cell growth.

ErbB Receptors↗
PubMedDate not supplied

Effects of IFN-gamma, TNF-alpha and EGF on the expression of HLA class I antigen and the proliferation of human hepatocellular carcinoma HepG2 cells.

In this study, the effects of IFN gamma, TNF alpha and EGF on the expression of HLA class I antigen and the proliferation of human hepatocellular carcinoma-HepG2 cells were investigated. In response to IFN gamma or TNF alpha stimulation, the expression of HLA class I mRNA in HepG2 cells was increased by 2-4 fold. Cell surface HLA class I antigen was also increased, but in comparison, the increase was not as high as HLA class I mRNA expression. This is probably due to the limitation of protein translational and post-translational processing. The enhancing effect of EGF on cell surface HLA class I antigen could be noted but was not very significant. IFN gamma and TNF alpha could also inhibit the proliferation of HepG2 cells. Interestingly, the effect of EGF on the proliferation of HepG2 cells depended on its concentration. At low concentrations, EGF increased cell proliferation in terms of thymidine incorporation. However, if the concentration of EGF was relatively high, it could also exert an inhibitory effect on thymidine incorporation into HepG2 cells. The remarkable morphological alteration was observed when HepG2 cells were exposed to EGF at concentrations higher than 5 ng/ml. This morphological alteration might be associated with the inhibitory effect of EGF at high concentrations on the proliferation of HepG2 cells.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Transmodulation of EGF receptor by interferon-gamma in human hepatocellular carcinoma HepG2 cells.

EGF receptor has been recognized to playing an important role in the regulation of normal and tumor cell growth. In this study, the transmodulatory effect of IFN gamma on EGF receptor of human hepatocellular carcinoma cell line HepG2 was investigated. The results demonstrated that IFN gamma was able to modulate EGF receptor of HepG2 cells by enhancing the tyrosine phosphorylation of the receptor. However, the effect appeared only if EGF was present, but not mediated by IFN gamma alone. No significant alteration was found in terms of the expression or the affinity of EGF receptor when HepG2 cells were treated with IFN gamma. In addition, EGF internalization in the cells was also not affected. Because IFN gamma is an inhibitory agent for the growth of HepG2 cells, this transmodulatory effect of IFN gamma on the tyrosine phosphorylation of EGF receptor might be associated with the inhibition of the growth of HepG2 cells.

Carcinoma, Hepatocellular↗