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Biomedical subjects

K W Cheng

Publications and source records attributed to K W Cheng.

At least 55 records · Page 3Linked to original sources
PubMed1990

Diclofenac sodium and low dose epidural morphine for postcesarean analgesia.

A randomized double-blind study of parturients after Cesarean section was undertaken to assess the efficacy of the combination of single dose intramuscular diclofenac sodium and low dose epidural morphine (EM) for postoperative analgesia. 50 parturients under epidural anesthesia were divided into 2 treatment groups: group A received 2 mg EM 30 min after the last dose of lidocaine and 3 ml normal saline i.m. at recovery room; group B received the same EM and 75 mg diclofenac i.m. postoperatively. Pain scores were compared at the 2nd, 4th, 8th, 12th, 18th, and 24th h. Results showed that group B was superior to group A in analgesic quality from the 8th h and thereafter (P less than 0.05) and 100% patients in group B were in the excellent to good analgesia categories at the 8th and 12th h record compared to 92% and 72% patients in group A respectively. Side effects were similar in both groups. The combination of NSAIDs with low dose EM could improve the analgesic quality after Cesarean section.

Adult↗
PubMed1989

Characterization of muscarinic acetylcholine receptors on intact neuroblastoma x glioma NG108-15 cell upon induced differentiation.

Studies have established that major increases in muscarinic acetylcholine receptor (mAchR) binding in the brain appear to coincide with synaptogenesis. The neuroblastoma x glioma hybrid NG108-15 cell line has been demonstrated to possess numerous functional characteristics of intact neurons, including synapse formation with myotubes. The present study examines and characterizes the mAchR on the hybrid NG108-15 cells during differentiation, induced by 1 mM dBcAMP. Specific binding of [3H]-QNB for differentiated cells increases gradually to a final level of 130% (P less than 0.05) over the control undifferentiated cells during the first 24 hr of incubation. Further, this increase of receptor sites appears to correlate proportionately to the degree of neurite extension of the differentiating cells. The dissociation rate constant at equilibrium (Kd) and maximum binding capacity (Bmax) have been determined to be 5.6 nM and 920 fmol/10(6) cells, respectively, for differentiated cells, and 4.4 nM and 400 fmol/10(6) cells, respectively, for undifferentiated cells. Computer analyses of the data obtained from saturation experiments reveal a single class of binding sites for [3H]-QNB on both differentiated and undifferentiated cells. The Hill plot analysis of the QNB-binding indicates a Hill coefficient (nH) of 1.0 and 0.91 for differentiated and undifferentiated cells, respectively, suggesting the unity of receptor sites with no co-operativity. Our results depict that increases of mAchRs on intact cells correlate with the degree of cellular differentiation.

Allosteric Regulation↗
PubMed1989

Modification of the indolamine content in neuroblastoma x glioma hybrid NG108-15 cells upon induced differentiation.

1. The neuroblastoma x glioma hybrid NG108-15 cell line has been widely studied as a neuronal model for its serotonergic, cholinergic, and peptidergic properties. 2. The catecholamine and serotonin content and that of their major metabolites have been determined by high-performance liquid chromatography with electrochemical detection (HPLC-EC) in NG108-15 cells under differentiated and undifferentiated conditions. 3. Cellular contents of L-DOPA, norepinephrine, (NE), L-epinephrine (EPI), and dopamine (DA) in differentiated cells, induced by 1 mM dibutyryl cyclic AMP (dBcAMP), are 149, 40, 129, and 124%, respectively, higher than those in undifferentiated cells. 4. 3,4-Dihydroxyphenethylacetic acid (DOPAC), the major metabolite of DA, is detectable only in differentiated cells. Similarly, DOPAC is present only in culture medium from differentiated cells, and not that of undifferentiated cells. 5. Serotonin (5-HT) is detectable only in undifferentiated cells; and the level of 5-hydroxyindoleacetic acid (5-HIAA), the major metabolite of 5-HT, is also 12.7% higher is undifferentiated cells. 6. Comparative analyses of differentiated and undifferentiated cells in monolayer cultures and undifferentiated cells cultured in the presence of 1 mM dBcAMP under suspension conditions suggest that change in the indolamine content is due to cellular changes upon morphological differentiation. 7. The clonal NG108-15 cell line is also catecholaminergic, in addition to cholinergic and serotonergic; and a shift of neurotransmitter pattern from serotonin to dopamine production occurs during morphological differentiation.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

A serum factor inducing neurite retraction of morphologically differentiated neuroblastoma x glioma NG108-15 cells.

It is well established that serum plays an important role in cell proliferation and differentiation. In this study, we have identified a serum factor that induces rapid neurite retraction of morphologically differentiated NG108-15 cells, cultured in serum-free medium containing 1 mM-dibutyryl cyclic AMP. The serum fraction of Mr greater than 30 x 10(3) induces neurite retraction in a manner identical to that of the whole serum. The neurite retraction activity in serum appears to be acid- and heat-stable. The molecular weight of the serum neurite retraction factor (NRF) has been demonstrated to be approximately 70 x 10(3) by gel permeation on LKB-Ultrogel AcA-44. The neurite retraction activity is dose-dependent, and the time required for half-maximal activity (t1/2) is 1.8 min. NRF is present in sera of various species studied, including human, cattle, sheep, rabbit and horse, but not in tissue extracts of kidney, heart, lung skeletal muscle, and brain of the rat. However, rat spleen and liver homogenates, at a protein content of 1 mg ml-1, caused slight neurite retraction. It is noteworthy that NRF is not detectable in cerebral spinal fluid. Our data on the properties of serum NRF indicate that it differs from all of the well-established growth factors, namely, NGF, EGF, PDGF, FGF, NSILA, ECGF and TGF. Further studies on purified NRF will delineate the biological role(s) of this serum factor in the process of maturation and differentiation of developing neurones.

Animals↗
PubMed1988

Steroidogenic relationships of gonadotrophin hormones in the ovary of the hen (Gallus domesticus).

The effects of chicken luteinizing hormone (cLH: IRC-2 and PRC AE1-1), turkey LH (B221B and HS-5-18), bovine follicle-stimulating hormone (bFSH: HS-2-17), chicken FSH (cFSH: PRC DC3(2) and AGCQSQ113445C), and turkey FSH (B150A and HS-1-153) on steroid output were evaluated by in vitro incubation of various ovarian tissues with the gonadotrophins. Output of androstenedione and estradiol was determined by 3-hr incubations of individual whole small follicles, classified by size and color as follows: small white (SWF, less than 1 mm), large white (LWF, 2-3 mm), and small yellow follicles (SYF, 5-10 mm). The effects of gonadotrophin preparations were also evaluated in large preovulatory follicles (F1-F5). Androstenedione and estradiol output was measured in incubation media from 100,000 theca cells and progesterone content was determined in the incubation media of 100,000 granulosa cells. All incubations were conducted in 1 ml of Medium 199 at 37 degrees. Steroid output was quantitated by radioimmunoassay of incubation media. Potency estimates were derived by calculation of a peak stimulation index. The standard reference preparation was bLH (NIAMDD-LH-B4). Steroidogenesis was stimulated by three avian LH preparations. preparations. PRC AE1-1 was the most potent, with IRC-2 and B150A showing approximately 50% of the biological activity of PRC AE1-1 in most tissues. Turkey LH HS-5-18 was generally not potent. The presence of multiple isohormones of LH was implied, as various LH preparations exhibited different potency estimates in different tissues. The effects of FSH on steroidogenesis were not significant in most cases. Although the addition of cFSH AGCQSQ113445C failed to significantly increase output of estradiol from small follicles, potency estimates of this preparation were 0.15, 0.20, and 0.13 relative to NIAMDD-LH-B4 follicles was more highly stimulated by LH than by FSH, and thus it would seem that FSH does not play a significant role in steroidogenesis in the hen's ovary. The results of this study suggest that steroid biosynthesis in the hen's ovary may be regulated by multiple forms of LH.

Androstenedione↗
PubMed1986

Plasma concentration profiles of gonadotrophins and testosterone in the adult boar.

Follicle stimulating hormone, luteinizing hormone and testosterone were measured by radioimmunoassay in plasma samples collected at 15 min intervals for a 12 h period in eight adult boars. Pulse increases in follicle stimulating hormone concentrations varied from one to four between individual boars while those of luteinizing hormone ranged from zero to four. The index of hormone production, provided by calculation of the area under the curve, was 0.5 +/- 0.51 microgram/L (means +/- S.D.) for follicle stimulating hormone and 0.46 +/- 0.11 microgram/L (means +/- S.D.) for luteinizing hormone. A significant correlation between changes in follicle stimulating hormone and luteinizing hormone values was seen in only two boars. The mean plasma testosterone concentration was 7.43 +/- 1.58 nM/L (means +/- S.D.). An identified increase in testosterone values occurred once in the 12 h period for six of the boars but was not noted in the other two animals. Although increases in testosterone could be identified with a previous pulse of luteinizing hormone, not all luteinizing hormone pulses were followed by an elevation in testosterone. A significant correlation between luteinizing hormone and testosterone was present in three of the eight animals. Follicle stimulating hormone and luteinizing hormone were measured in samples similarly collected two weeks after castration in the same eight boars. The number of pulses of follicle stimulating hormone increased significantly (p less than 0.05) and ranged from 3 to 7/12 h. The index of production of 1.8 +/- 1.15 micrograms/L (mean +/- S.D.) also represented a significant increase (p less than 0.05) over precastration follicle stimulating hormone values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

A homologous radioimmunoassay for turkey prolactin: changes during the reproductive and ovulatory cycle.

A rabbit antiserum to turkey prolactin (tPRL) was used in a homologous radioimmunoassay with 125I-tPRL. This assay did not cross-react with turkey luteinizing hormone (tLH), chicken LH (cLH), turkey follicle stimulating hormone (tFSH), or turkey growth hormone (tGH). The within- and between-assay coefficients of variation were 6.2 and 14.0%, respectively, and the useful range of the standard curve extended from .5 to 10.0 ng/tube. In two separate experiments, the plasma concentrations of prolactin were estimated throughout the reproductive cycle of the turkey hen using a heterologous assay previously described and the current homologous assay. The correlation coefficients between the two estimates of prolactin in nonbroody hens were .84 and .83. In both experiments, the plasma concentrations of prolactin were low when egg production was initiated, rose to maximum concentrations 5 to 7 weeks later, and thereafter declined. In the first experiment, the hens were selected because their plasma contained large amounts of immunoreactive PRL during the first 2 weeks after photostimulation in the heterologous tPRL assay. This immunoactivity was not evident when using the homologous assay. Using the heterologous assay, no differences in the plasma prolactin concentrations were detected between broody and nonbroody hens during the reproductive cycle. However, using the homologous assay, a sustained increase in the concentration of prolactin was noted for several weeks after broody behavior was detected. The maximum levels observed in broody hens were equal to those observed when the rate of egg production was maximal. There were no statistically significant changes in the concentrations of prolactin during the ovulatory cycle.

Animals↗
PubMed1981

Characterization of a radioimmunoassay for ovine FSH utilizing an anti-bovine FSH serum.

The sensitivity of the assay, utilizing a bovine FSH antiserum and 125I-labelled bovine FSH tracer, is 5 ng NIH-FSH-S6/ml, and cross-reactivities of other ovine pituitary glycoprotein and protein hormones (LH, TSH, growth hormone and prolactin) are less than 1.0%. Both pituitary and serum FSH of the sheep cross-react in a manner parallel with that of standard NIH-FSH-S6. Serum FSH concentrations in 4 ewes at various times after the onset of oestrus peaked more or less coincidently with the preovulatory increase of serum LH. The serum levels of FSH and LH did not correlate proportionally but fluctuated considerably in individuals animals. The radioimmunoassay system appears to be sensitive and specific for measuring serum concentrations of FSH in rams and ewes in different physiological states.

Animals↗
PubMed1981

Isolation and characterization of turkey prolactin.

Prolactin from frozen turkey pituitary glands was purified by alkaline ethanol extraction of the pituitary residue after pre-extractions of the gonadotrophins and GH, followed by gel filtration on Sephadex G-100 and DEAE-cellulose column chromatography at different pH. A specific radioligand--receptor assay for ovine prolactin was used to locate the activity in eluates after column chromatography and gel filtration. The potency of the highly purified turkey prolactin was characterized by a radioligand--receptor assay to be 3.40 i.u./mg and by a heterologous radioimmunoassay to be 35 i.u./mg as compared to purified ovine prolactin as standard. The yield of turkey prolactin was 3 mg/100 g frozen pituitary glands. The purified turkey prolactin consisted of three protein bands upon polyacrylamide gel electrophoresis and the molecular weight was estimated to be 22000 by SDS--polyacrylamide gel electrophoresis. Turkey prolactin was rich in aspartic acid, glutamic acid and leucine, but lacking in methionine.

Amino Acids↗
PubMed1981

Changes in the plasma concentrations of luteinizing hormone, progesterone, oestradiol and testosterone and in the binding of follicle-stimulating hormone to the theca of follicles during the ovulation cycle of the hen (Gallus domesticus).

The changes in the binding of FSH during follicular maturation were examined in the hen using 125I-labelled bovine FSH (bFSH) and unlabelled bFSH. The binding of 125I-labelled bFSH was not inhibited by bovine LH or chicken LH but was inhibited by extracts of chicken pituitary glands. The ovarian stroma, which contained both interstitial tissue and small follicles, bound the greatest amount of FSH. As the follicles progressed through the yolk-filled hierarchy of maturation, they bound decreasing amounts of FSH. In the two largest follicles of the hierarchy, there was a significant increase in the binding of FSH 12-16h before ovulation. There were two peaks in the concentrations of LH; a preovulatory peak occurred 4-6h before ovulation and a second peak occurred 14-16h before ovulation. Plasma concentrations of testosterone, oestradiol and progesterone began to rise 9, 8 and 6h, respectively, before ovulation. These data are consistent with the hypothesis that changes in the gonadotrophin concentration and binding regulate the order of the follicular hierarchy and the onset of preovulatory steroidogenesis in the hen.

Animals↗
PubMed1980

The hypothalamo-pituitary gonadotrophic axis of suckled and nonsuckled dairy cows postpartum.

The objective was to determine whether the suckling-induced delay in return to estrus postpartum could be explained by changes in hypothalamic LHRH content or ability of the pituitary to release LH and FSH in response to LHRH or 59 mM K+ in vitro. In addition, serum concentrations of several other hormones were measured. Nine Holstein cows were suckled ad libitum by two calves and milked by machine twice daily and eight were milked by machine only from calving until slaughter on day 14 postpartum. On day 13 postpartum, blood was collected at 15-min intervals from 0815 to 1200 hr and from 2015 to 2400 hours. Suckled cows had lower (P less than .05) mean serum LH concentrations on day 13 postpartum than did nonsuckled controls. This decrease resulted from a 60% reduction in frequency and a 40% reduction in amplitude of episodic LH peaks. Suckling did not affect body weight change postpartum or serum concentrations of progesterone, estradiol-17 beta, total glucocorticoids, prolactin or FSH during the first 14 days postpartum. The suckling-induced decrease in serum LH was not reflected by a reduction in hypothalamic LHRH or pituitary LH on day 14 postpartum. However, pituitary explants from suckled cows on day 14 postpartum secreted 50% less (P less than .01) LH in response to LHRH (25 ng/ml for 30 min) or K+ (59 mM for 30 min) in vitro than did those from nonsuckled cows. Secretion of FSH was increased 20-fold by LHRH and K+ in vitro, but differences due to suckling treatment were not significant. Decreased frequency and amplitude of episodic LH secretion in vivo and reduced capacity of pituitaries to respond to LHRH may be the cause of suckling-induced inhibition of postpartum ovulation in cattle.

Animals↗
PubMed1979

Development of glycoprotein hormones and their alpha- and beta-subunits in bovine fetal pituitary glands. I. Quantitation of thyrotropin, follicle-stimulating hormone, and luteinizing hormone by radioligand receptor assays.

The development of TSH, FSH, and LH in bovine fetal pituitary glands was studied by the respective radioligand receptor assays. The content of pituitary TSH increased gradually in fetuses of both sexes throughout gestation, and no significant difference was observed for the pituitary concentration of TSH between male and female fetuses at different stages of gestation. The pituitary content of FSH increased gradually in male fetuses, but increased dramatically in female fetuses after midgestation. Similarly, the concentration of pituitary FSH was 2- to 3-fold higher in female than male fetuses after midgestation. The pituitary content of LH increased gradually and proportionally with the age of the fetus, and no significant difference was observed between sexes. However, the concentration of pituitary LH remained relatively constant for both sexes throughout gestation.

Animals↗
PubMed1978

Isolation and characterization of the subunits of bovine follitropin.

Highly purified bovine follitropin was dissociated into its alpha- and beta-subunits after treatment with 1 M-propionic acid. The dissociated subunits were fractionated by chromatography on DEAE-cellulose and further purified by gel filtration on Sephadex G-100. The isolated alpha- and beta-subunits were biologically inactive, but their recombinants regenerated 80% of the follitropin activity. The alpha-subunit of bovine follitropin recombined with the beta-subunits of bovine lutropin and thyrotropin to regenerate 70% of lutropin and 50% of thyrotropin activities respectively. The beta-subunit of bovine follitropin recombined with the alpha-subunit of either bovine lutropin or thyrotropin to regenerate about 75% of follitropin activity. Recombinations were monitored by specific radioligand-receptor assays and polyacrylamide-gel electrophoresis. The elution volumes of the alpha- and beta-subunits of bovine follitropin after gel filtration on Sephadex G-100 were almost identical. The amino acid composition of bovine follitropin-alpha was low in histidine, arginine, isoleucine and leucine, but relatively high in lysine, threonine and glutamic acid. The bovine follitropin-beta contained one methionine residue and low amounts of histidine and phenylalanine, but relatively high in aspartic acid, threonine and glutamic acid. The N-terminal residues of the alpha- and beta-subunits of bovine follitropin were identified to be phenylalanine and glycine respectively.

Amino Acids↗
PubMed1978

Development and characterization of a homologous radioimmunoassay for bovine follicle-stimulating hormone.

A radioimmunoassay for bovine FSH has been developed using a rabbit antiserum against highly purified bovine FSH (160 X NIH-FSH-S1) and a 125I-labelled tracer of the same preparation. The sensitivity was 0.25 ng/ml for purified bovine FSH or 25 ng/ml with reference to a crude bovine FSH (NIH-FSH-B1) standard. Purified bovine LH and TSH showed cross-reactivities of less than 1%, while their subunits and other purified protein hormones showed no significant inhibition at concentrations up to 100 ng/ml. Ovine FSH cross-reacted significantly but in a non-parallel manner; human and rat FSH cross-reacted only slightly. The concentrations of FSH (means +/- S.E.M.) in the sera of cows (n = 12), cows at oestrus (4), bulls (7) and steers (9) were measured as 25.4 +/- 4.7, 58.4 +/- 12.6, 45.7 +/- 9.5 and 120.2 +/- 36.0 ng/ml respectively. The FSH content of bovine pituitary glands varied greatly between individuals, from 2 to 25 microgram/mg tissue. The inhibition curves of pituitary and serum FSH were parallel to that of the bovine FSH standard.

Animals↗
PubMed1977

Presence of subunit structure in bovine follicle-stimulating hormone.

Highly purified bovine follicle-stimulating hormone (FSH) potency 164 X NIH-FSH-S-1 by bioassay was estimated to be 210 +/- 4.2 X NIH-FSH-S-1 by radioligant-receptor assay using 125I-bovine FSH as tracer but only 120 +/- 1.8 X NIH-FSH-S-1 when 125I-human FSH tracer was used. The presence of subunit structure in bovine FSH was revealed by SDS-polyacrylamide gel electrophoresis. Furthermore, treatment of bovine FSH with 1 M propionic acid resulted in marked changes of mobilities upon polyacrylamide gel electrophoresis and elution profiles after gel filtration on Sephadex G-100 in addition to loss of biological activity by radioligand-receptor assay. After incubation, the propionic acid-treated bovine FSH recovered about 75% of the receptor-binding activity and regenerated protein bands of identical electrophoretic mobilities as the native hormone.

Animals↗