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C Wang

Publications and source records attributed to C Wang.

At least 1,153 records · Page 64Linked to original sources
PubMed1991

Differential glucocorticoid regulation of glucagon gene expression in cell lines derived from rat and hamster islet cell tumors.

Glucocorticoid regulation of peptide hormone gene expression was studied in two cell lines derived from rodent islet cell tumors. In rat RIN1056A cells, dexamethasone reduced the levels of glucagon mRNA transcripts while markedly inducing the expression of the angiotensinogen gene. In contrast, dexamethasone had no effect on the regulation of glucagon gene expression in hamster InR1-G9 cells. Wild type InR1-G9 cells did not support the induction of the murine mammary tumor virus promoter by glucocorticoids, suggesting that these cells lacked the necessary cellular factor(s) for glucocorticoid responsiveness. Introduction of the glucocorticoid receptor into wild type InR1-G9 cells restored glucocorticoid induction of the murine mammary tumor virus promoter, but not glucocorticoid regulation of glucagon gene expression. Dexamethasone treatment of Sprague-Dawley rats had no effect on the levels of pancreatic glucagon mRNA transcripts. The results of these studies demonstrate that glucocorticoid regulation of glucagon gene expression is restricted to the immortalized RIN1056A cell line, providing additional evidence for cell-specific diversity in the regulation of peptide hormone gene expression in neuroendocrine tumors.

Adenoma, Islet Cell↗
PubMed1991

Combined chemical and mechanical effects on free radicals in UHMWPE joints during implantation.

An electron spin resonance (ESR) technique is employed to determine the free radical distribution in the articulating surfaces of retrieved acetabular cups and knee-joint plateaus (retrieved after more than 6 years of implantation). Similar measurements made on samples prepared from cyclically stressed and unstressed cups, and on samples following oxidations in nitric acid and intralipid solutions provided sufficient data to gain more knowledge about the combined chemical and mechanical effects on PE free radicals during implantation. In UHMWPE free radicals are primarily initiated by gamma-ray sterilization; however, during implantation, peroxy (scission type) free radicals are formed and reach a maximum concentration level (equilibrium state) due to oxidation by chemical (hemoglobin and/or synovial fluids) environment of the joints. Subsequently, due to frictional heating and stress in the loading zones, free radical reaction is accelerated and their number is reduced only in those areas. This is consistent with the observations of a temperature rise in acetabular cups during in vitro frictional wear stress tests and in vivo telemetry observations, as reported by others. Compared with the previously reported SEM micrographs the low-free-radical regions are correlated with high-wear areas and the high-free-radical regions with the low-wear areas.

Biocompatible Materials↗
PubMed1991

Hydrocortisone in culture protects the blast cells in acute myeloblastic leukemia from the lethal effects of cytosine arabinoside.

The blast cells in acute myeloblastic leukemia (AML) respond to many of the same regulatory mechanisms that control normal hemopoiesis. These include the growth factors that bind to membrane receptors and steroid hormones or vitamins that have intracellular receptors. We report the effects in culture of the steroid glucocorticoid hydrocortisone on freshly explanted AML blasts from patients and on two continuous AML cell lines. Only small changes in clonogenic cell numbers in suspension cultures were seen in the presence of hydrocortisone. The most striking effect of the hormone was on the sensitivity of blasts cells to cytosine arabinoside (ara-C). In contrast to the response of AML blast cells to retinoic acid, a ligand for intracellular steroid receptors that sensitizes some blast populations to ara-C, hydrocortisone reduced the toxic effects of the drug. The protective action of hydrocortisone was not mediated through the cell cycle since exposure of blasts to hydrocortisone did not affect the percentage of cells in DNA synthesis as measured with the tritiated thymidine (3HTdR) "suicide" technique. The hydrocortisone effect could be demonstrated using a pulse (20 min) exposure protocol. Blasts pulsed with increasing specific activities of 3HTdR showed the usual response pattern with an initial loss in plating efficiency to about 50% of control, followed by a plateau, regardless of whether the cells had been exposed to hydrocortisone. Control blasts exposed to increasing ara-C concentrations gave very similar dose-response curves; in striking contrast, blast cells cultured in hydrocortisone, then pulsed with ara-C did not lose colony-forming ability even though the same population was sensitive to 3HTdR. The hydrocortisone effect was dose and time related; protection from ara-C increased from 10(-8) to 10(-5) M and was seen after 4 hr exposure but required 8 hr to reach a maximum. We conclude that hydrocortisone can protect blasts from the lethal effects of ara-C even while the cells are in active DNA synthesis.

Blast Crisis↗
PubMed1991

Effect of norepinephrine depletion on audiogenic-like seizures elicited by microinfusion of an excitant amino acid into the inferior colliculus of normal rats.

Infusions of an excitant amino acid, N-methyl-D-aspartate (NMDA) into the inferior colliculus (IC) render normal rats susceptible to audiogenic seizures (AGS) and/or spontaneous audiogenic-like seizures without tonic components. The excess excitant amino acid in the IC and the anticonvulsant effects of NMDA antagonists in genetically epilepsy-prone rats (GEPRs), along with innate norepinephrine (NE) deficits and anticonvulsant effects of NE agonists in these animals suggest a mutual role of excitant amino acids and NE in regulating AGS in GEPRs. Saline or 6-hydroxydopamine (6-OHDA, 4 micrograms/side in 2 microliters) was infused bilaterally into the locus coeruleus (LC) of normal male rats and guide cannulas were implanted into the IC. Two weeks later, NMDA was infused bilaterally into the IC (0.5 microliters; 10 nmol/side) and 10 min later the rats were subjected to an electric bell (110 db, 60 s) unless preceded by spontaneous tonic seizures. Tonic seizures were not observed in male rats following NMDA infusions in rats with LC infusions of saline. However, a marked increase in the incidence of tonic seizures was observed in the 6-OHDA-treated rats which were markedly depleted of brain NE as determined by HPLC. These findings indicate that a NE deficit greatly enhances the incidence of tonic convulsions and support the hypothesis that an excitant amino acid excess in the GEPR IC may act to initiate AGS, whereas the NE deficit may allow expression of the tonic components of AGS seen in some GEPRs.

Acoustic Stimulation↗
PubMed1991

Computer-assisted assessment of human sperm morphology: usefulness in predicting fertilizing capacity of human spermatozoa.

OBJECTIVE: The usefulness of sperm morphology to predict the outcome of human sperm fertilizing capacity was examined. DESIGN, SETTING, PATIENTS: Semen samples from 50 male patients attending the infertility clinic of a tertiary referral institution were studied. MAIN OUTCOME MEASURES: Sperm morphology was classified both by visual assessment and computer-assisted image analysis. In addition, morphometric analysis of the spermatozoa was measured by the morphologizer. Multivariate discriminant analysis was used to evaluate the usefulness of these morphology parameters for predicting the outcome of the zona-free hamster oocyte sperm penetration assay. RESULTS: The manually derived percent of spermatozoa with normal and small head were selected to be of discriminating value in predicting the outcome of the zona-free hamster oocyte penetration test. The accuracy of correctly classifying the outcome of zona-free hamster oocyte penetration test by these two parameters in combination was 84%, whereas assessment of sperm morphology with morphometric analysis by the morphologizer selected a total of eight variables, which together predicted sperm fertilizing capacity with 74% accuracy. Addition of the morphologizer-derived parameters to those derived manually did not significantly improve the predictive value. CONCLUSION: We conclude that the results of the zona-free hamster egg penetration test could be predicted using manual assessment of sperm morphology and computer-assisted morphometric analysis did not add further information.

Animals↗
PubMed1991

Comparison of measurements of human sperm motility characteristics by the automated CellSoft system and time-exposure photomicrography.

Human sperm motility characteristics in 28 semen samples with sperm concentrations less than 40 x 10(6) ml-1, as determined by the World Health Organization manual analysis (WHO, 1987), were measured by the automated CellSoft semen analyser (Cryo Resources Ltd, New York, NY, USA) using different system parameter settings (Mortimer & Mortimer, 1988a). The results were compared with those obtained by time-exposure photomicrographic (TEP) analysis. It was found that the settings of the minimum video frame rate and the threshold velocity used to distinguish motile from immotile sperm by the automated CellSoft system had a significant influence on measurements of percentage motility but not on linear velocity. At the five different parameter settings used in the present study, the automated CellSoft system gave significantly lower mean values for percentage motility in comparison with the WHO manual and TEP analyses. Measurements for linear velocity between the automated CellSoft system and TEP analyses were found not to be significantly different in these defined semen samples.

Humans↗
PubMed1991

Propylthiouracil hypersensitivity with circumstantial evidence for drug-induced reversible sensorineural deafness: a case report.

Severe adverse reactions to propylthiouracil occur in 1-5% of patients. Three major side effects, namely agranulocytosis, hepatotoxicity and drug-induced hypersensitivity, have been described though these syndromes are not distinct entities and there can be overlaps in the clinical manifestations. The drug-induced hypersensitivity may be an immune-mediated reaction with multiorgan involvement in which a combination of polyarthritis, cutaneous vasculitis and fever is common. We report a patient with propylthiouracil-induced hypersensitivity with an unusual combination of high spiking fever, migratory polyarthritis, reversible sensorineural deafness, normochromic normocytic anaemia, leucocytosis and hepatotoxicity associated with polyclonal activation of multiple autoantibodies. This case illustrates the highly variable clinical manifestations of the syndrome. The prompt recovery upon withdrawal of the drug indicates the importance of early diagnosis.

Adult↗
PubMed1991

Clinical and biochemical parameters of androgen action in normal healthy Caucasian versus Chinese subjects.

Stimulation of androgen-sensitive hair follicles is mediated by dihydrotestosterone (DHT), which is formed in these tissues by 5 alpha-reduction of testosterone. A possible mechanism for increased body hair in some human populations might, therefore, be an increase in 5 alpha-reductase activity, resulting in elevated tissue levels of DHT. If present, this finding could have other important clinical implications, since the 5 alpha-reductase enzyme is pivotal in the pathophysiology of prostatic disease. To explore differences in clinical and biochemical parameters of androgen action, we conducted a study of 184 caucasian and Chinese subjects in whom we evaluated chest hair density and serum levels of androgen precursors and 5 alpha-reduced androgen metabolites. Differences in chest hair density were most notable in the men, in whom comparative mean chest hair scores (using a scale of 0-4) were 3.0 vs. 0.8 (P less than 0.0001), caucasian vs. Chinese. Levels of 5 alpha-reduced androgen products were also strikingly higher in the caucasian vs. Chinese subjects. Serum 3 alpha-androstanediol glucuronide levels (nanomoles per L) were 34.7 +/- 2.4 vs. 19.7 +/- 0.9 (P less than 0.001) for the men and 21.5 +/- 3.2 vs. 9.4 +/- 0.6 (P less than 0.001) for the women, and serum levels of androsterone glucuronide (nanomoles per L) were 179 +/- 26 vs. 107 +/- 7 (P less than 0.01) for the caucasian vs. Chinese men and 173 +/- 23 vs. 81 +/- 9 (P less than 0.001) for the women. Serum levels of total and bioavailable testosterone did not differ between the racial groups, but serum levels of the precursor androgens, dehydroepiandrosterone sulfate and androstenedione, were significantly higher in the caucasian vs. Chinese men, but not in the women. We conclude that increased serum levels of 5 alpha-reduced androgen metabolites in caucasians vs. Chinese subjects provide circumstantial evidence for a racial difference in 5 alpha-reductase activity and suggest a mechanism for the increased body hair observed in the caucasian men. Increased levels of precursor androgens may also play a role.

Adolescent↗
PubMed1991

Mast cell growth factor, a ligand for the receptor encoded by c-kit, affects the growth in culture of the blast cells of acute myeloblastic leukemia.

The c-kit proto-oncogene encodes a transmembrane receptor with a tyrosine kinase internal domain. C-kit has been mapped to the W locus in the mouse, and the gene encoding the ligand has been shown to be the product of the murine SI locus. Previous genetic studies have shown that the murine W and SI loci play important roles in the normal function of hemopoietic stem cells. As these stem cells have been identified as the origins of abnormal clones in acute myeloblastic leukemia (AML), a study was begun of c-kit in AML. By Northern blot analysis, it was shown that all of 21 blast populations from AML patients were kit expression positive, but some AML cell lines did not transcribe detectable c-kit mRNA. This study is now extended to the responses of freshly obtained AML cells and cell lines to the ligand, mast-cell growth factor (MGF). In culture, fresh cells usually responded to added ligand with increases in both self-renewal and terminal divisions. The most obvious effects were seen when MGF was combined with either IL-3 or G-CSF. The response of cell lines to MGF mirrored their expression of c-kit; expression positive lines responded in culture with patterns similar to those seen for fresh cells. C-kit expression negative cells did not respond to MGF. RNA prepared from the cells giving rise to one such line, OCI/AML-5, was available for study. mRNA for c-kit could not be detected in this RNA sample by Northern blot analysis or the polymerase chain reaction. Thus the heterogeneity found in AML blast populations extends to the involvement of c-kit and its ligand in growth regulation, although blast populations without this regulatory apparatus appear to be rare.

Cell Division↗
PubMed1991

OCI/AML-4 an acute myeloblastic leukemia cell line: regulation and response to cytosine arabinoside.

This paper describes the properties of a continuous cell line derived from the blast cells of a patient with acute myeloblastic leukemia (AML), secondary to the treatment of Hodgkin's disease. The line grows slowly without stimulation but responds to interleukin-3 (IL-3), GM-CSF and mast cell growth factor (MGF), a ligand for the receptor encoded by the c-kit oncogene. When OCI/AML-4 cells are exposed to MGF with IL-3 or GM-CSF, additive or synergistic effects are seen. Combinations of MGF and G-CSF, IL-6 or CSF-1 give less growth than MGF alone. OCI/AML-4 cells are sensitive to retinoic acid; a dose related decrease in clonogenic cells is observed when OCI/AML-4 cells are exposed to retinoic acid in suspension culture. OCI/AML-4 cells are sensitive to cytosine arabinoside (ara-C), but the ara-C dose-response curve can be changed by altering the regulatory milieu in suspension culture. The cells are more ara-C sensitive in MGF or G-CSF than in IL-3 or GM-CSF. Following a 24 h exposure to retinoic acid, the ara-C sensitivity increases; in contrast, after a similar exposure to hydrocortisone, the cells become less ara-C sensitive. These changes in ara-C sensitivity occur in cells that are actively making DNA, as indicated by the reduction in colony formation after exposure to tritiated thymidine. Since OCI/AML-4 cells respond to many of the regulators that affect the growth of freshly obtained AML blast cells, it is proposed that this cell line may be useful for the study of regulation on AML in general and the interaction between different regulators in particular.

Antigens, CD↗
PubMed1991

Granulocyte-macrophage colony-stimulating factor and interleukin-3 protect leukemic blast cells from ara-C toxicity.

The blast cells of acute myeloblastic leukemia (AML) usually require growth factors for optimum proliferation in cell culture. Growth factors also affect the sensitivity of AML blast cells to cytosine arabinoside (ara-C). Others have reported that factor-treated cells are more ara-C sensitive than blasts in culture without factors. These authors have reported previously that AML blasts grown with rG-CSF, with or without GM-CSF, are more sensitive than cells in GM-CSF alone. This paper reports experiments which show that changes in the ara-C sensitivities of blast cells in different growth factors are not explained by changes in the percentage of cells in the DNA synthesis (S) phase of the cycle. Blasts freshly obtained from five AML patients were cultured in either rG-CSF, rGM-CSF, or rIL-3; they were then exposed to 20 min pulses of either high specific activity tritiated thymidine (3HTdR) or a high concentration of ara-C. Regardless of the factor present, the pulse of 3HTdR decreased the number of clonogenic cells by about 50%, the result expected for actively proliferating cells with an S phase occupying about half the cycle time. The same result was found for four of the five blast cell populations grown in G-CSF and pulsed with ara-C; in contrast, clonogenic cells grown in GM-CSF or IL-3 from these four populations were not killed by ara-C. The blasts from the fifth patient were ara-C resistant under all conditions. It was concluded that exposure to GM-CSF or IL-3 decreased ara-C sensitivity in blasts that were actively making DNA. The observation was explored in more detail using a cell line (OCI/AML-1a) that is both ara-C sensitive and growth factor dependent. These studies showed that about 15 h of growth in factor are required for a change in ara-C sensitivity.

Adult↗
PubMed1991

[Determination of megestrol acetate and estradiol valerate in injection of microencapsulated compound megestrol acetate by secondary derivative spectrophotometry].

The paper reports the simultaneous determination of megestrol acetate and estradiol valerate in the injection of microencapsulated compound megestrol acetate by secondary derivative spectrophotometry. The experimental results showed that the average recoveries of the two drugs were 98.8% and 98.0%, respectively, and that the coefficients of variation were 0.71% and 1.81%, respectively.

Capsules↗
PubMed1991

[Pulmonary vascular resistance index as parameter for detecting right ventricular afterload].

We studied the pulmonary haemodynamics in 62 cases of chronic cor pulmonale due to chronic obstructive pulmonary disease (COPD). Present criteria for pulmonary hypertension are: pulmonary arterial mean pressure greater than 20 mmHg and/or pulmonary systolic pressure greater than 30 mmHg at rest and pulmonary mean pressure greater than 30 mmHg after exercise. We found that 24 of our 62 cases did not meet these criteria even after exercise despite clinical evidence of cor pulmonale. However, in all cases the pulmonary vascular resistance index (PVRI) was increased (greater than 177 dyn.s.m2.cm-5) and significantly elevated after exercise. It is suggested that 1) it is inappropriate to set the criteria based solely on pulmonary artery pressure to define pathologically increased right ventricular overload; 2) the measurement of PVRI allows the concept of relative and latent pulmonary hypertension to be introduced; 3) PVRI is a more sensitive index of right ventricular overload than pulmonary artery pressures, especially when referring to the result of exercise test.

Aged↗