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Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 883 records · Page 49Linked to original sources
PubMed1993

Cloning, sequencing and expression in E. coli of interferon-omega 1 gene.

Human interferon omega 1 (huIFN-omega 1) gene was isolated and cloned from chromosome DNA derived from a Chinese fetal liver via polymerase chain reaction (PCR). By determining its nucleotide sequence we proved that the 88th codon should be GGA, coding for Gly. After engineering the original IFN-omega 1 gene clone to a form that may be expressed as a nonfused protein, we also took the IFN-omega 1 gene under the control of the PRPL promoter with an expression vector pBV220 in E. coli. The antivirus activity of the recombinant IFN-omega 1 is about 6.5 x 10(7) units/L CULTURE (OD600 = 0.75). Since IFN-omega 1 not only has antivirus activity but also shows considerably high homology with animal trophoblast proteins which have been proved antiluteolysins as a maternal recognition signal for pregnancy, we believe that study on it will be practically and theoretically significant.

Amino Acid Sequence↗
PubMed1993

[Potentiation of morphine- and ohmefentanyl-induced analgesia by cholecystokinin receptor antagonists in rat].

It has been reported that intrathecal (i.t.) injection of CCK-8 showed a marked antagonism to analgesic effects mediated by mu-opioid receptors in rat. The present study was performed to ascertain whether the blockade of endogenously released CCK-8 by potent and selective CCK-A antagonist devazepide and CCK-B antagonist L-365260 would affect opioid analgesia at the spinal cord level. A marked potentiation of the analgesic effect induced by morphine (4 mg/kg, sc) was produced by i.t. injection of 100 ng devazepide or 2.5 ng L-365260. Dose-response curves for the enhancement of the two drugs on morphine analgesia were bell-shaped. Intrathecal injection of 66 ng devazepide or 1.25 ng L-365260 was also shown to potentiate the analgesic effect induced by the selective mu-opioid agonist ohmefentanyl (OMF) (32 ng, i.t.). The dose-response curves were also bell-shaped. Devazepide or L-365260 per se produced no significant changes in rat tail flick latency (TFL). The above results are interpreted to mean that endogenously released CCK-8 in the spinal cord plays an antagonistic role to opioid analgesia, and it is the CCK-B receptors that mediate the anti-opioid effect since the dose of devazepide is 40-50 times higher than that of L-365260.

Analgesics↗
PubMed1993

[Experimental method and clinical significance of hidden rheumatoid factors].

Hidden rheumatoid factor (HRF) was detected in rheumatoid arthritis (RA) serum with ELISA after separation and dissociation of immune complex (IC). It was found that 60% of the patients with active RA has positive latex fixation test, whereas 96% of them has been demonstrated to have IgM hidden rheumatoid factor (HIgMRF) and 70% of them IgG hidden rheumatoid factor (HIgGRF). When the disease was controlled, HIgMRF and HIgGRF was found in 24% and 12% respectively. The difference was significant with P < 0.01. Our results show that the presence of HRF in RA patients is related with the activity of the disease, but not with duration of disease, sex and age.

Adult↗
PubMed1993

Effects of antiepileptic drugs on reaction time, attention, and impulsivity in children.

Simple, choice, and complex reaction times, attention (variability of responses and omission errors), and impulsivity (commission and wrong-hand errors on choice and complex reaction time) were repeatedly measured in 111 epileptic children, aged 5 to 13 years, tested a total of 232 times. Antiepileptic drugs (AEDs) were started, stopped, and adjusted throughout the study period, for a variety of clinical indications, and AED serum levels were monitored. The relationship of performance to AED serum level was examined. Overall the nonspecific effect of AEDs was minimal: higher total serum levels of AEDs correlated with more impulsive errors on complex reaction time testing only. In contrast, in 54 children receiving carbamazepine monotherapy, we found a dose-related beneficial effect upon reaction time, with higher serum levels associated with faster responses and fewer omission errors, particularly on complex reaction time. Phenobarbital caused minimal dose-related effects: only variability and impulsive errors increased with increasing serum levels, and only on one segment of the test (73 subjects).

Adolescent↗
PubMed1992

UNC-5, a transmembrane protein with immunoglobulin and thrombospondin type 1 domains, guides cell and pioneer axon migrations in C. elegans.

The unc-5 gene is required for guiding pioneering axons and migrating cells along the body wall in C. elegans. In mutants, dorsal migrations are disrupted, but ventral and longitudinal movements are largely unaffected. The gene was tagged for molecular cloning by transposon insertions. Based on genomic and cDNA sequencing, the gene encodes UNC-5, a transmembrane protein of 919 aa. The predicted extracellular N-terminus comprises two immunoglobulin and two thrombospondin type 1 domains. Except for an SH3-like motif, the large intracellular C-terminus is novel. Mosaic analysis shows that unc-5 acts in migrating cells and pioneering neurons. We propose that UNC-5 is a transmembrane receptor expressed on the surface of motile cells and growth cones to guide dorsal movements.

Amino Acid Sequence↗
PubMed1992

Catabolite gene activator protein (CAP) is not an "acidic activating region" transcription activator protein. Negatively charged amino acids of CAP that are solvent-accessible in the CAP-DNA complex play no role in transcription activation at the lac promoter.

It has been suggested that the catabolite gene activator protein (CAP) uses an "acidic activating region" transcription activation mechanism and that Glu171 of CAP is the critical amino acid of the "acidic activating region" of CAP (Irwin, N., and Ptashne, M. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 8315-8319). In this paper, we show, contrary to the previously published report, that substitution of Glu171 of CAP fails to result in a specific defect in transcription activation at the lac promoter. Furthermore, in this paper, we show that substitution of each other negatively charged amino acid of CAP that is solvent-accessible in the CAP-DNA complex fails to result in a specific defect in transcription activation at the lac promoter. We conclude that CAP does not use an acidic activating region transcription activation mechanism in transcription activation at the lac promoter.

Amino Acids↗
PubMed1992

Thyroid hormone concentrative uptake in rat erythrocytes. Involvement of the tryptophan transport system T in countertransport of tri-iodothyronine and aromatic amino acids.

The kinetic properties of transport system T, which is specific for uptake of aromatic amino acids, were studied in rat erythrocytes in the presence of leucine in order to block the neutral amino acid transport system L. Since the triiodothyronine (T3) transport system and system T are closely related, the trans effect of T3 and tryptophan on [3H]tryptophan transport and the trans effects of aromatic amino acids on [125I]T3 transport were studied. Equilibrium-exchange, zero-trans and infinite-trans studies of [3H]tryptophan transport indicated that system T in rat erythrocytes is a simple carrier with exchanging properties resulting in trans-acceleration of influx and trans-inhibition of efflux when tryptophan was present at the trans side of the membrane. In erythrocytes preloaded with unlabelled tryptophan, countertransport resulted in a 7-fold accumulation of labelled substrate inside the cells. T3 on the trans side of the membrane inhibited both influx and efflux of tryptophan, with Ki values similar to the Km values of the T3 transport system. Extracellular tryptophan trans-inhibited [125I]T3 efflux in a manner similar to [3H]tryptophan efflux. Preloading erythrocytes with tryptophan resulted in trans-acceleration of T3 uptake and a transient 5-fold accumulation of free T3 into erythrocytes. Phenylalanine and tyrosine (but not the D-isomer of tryptophan or non-aromatic amino acids) also produced trans-acceleration for T3 uptake and T3 countertransport. These results are compatible with a kinetic model assuming a common simple carrier of T3 and tryptophan transport and point to a countertransport pathway driving the uphill uptake of T3 by hetero-exchange with intracellular aromatic amino acids.

Animals↗
PubMed1992

A multivariate study of protective effects of Zn and Cu against nephrotoxicity induced by cadmium metallothionein in rats.

Factorial experimental design was used to study the protective effects of Zn and Cu on cadmium-metallothionein(CdMT)-induced nephrotoxicity in male Wistar rats. In the factorial design two levels of Zn (0 and 25 mg/kg body weight), two levels of Cu (0 and 12.5 mg/kg), and two levels of CdMT (0.1 and 0.4 mg of Cd/kg) were used as varied factors. The factorial design was complemented with a center point with all three variables at an intermediate setting, i.e., Zn at 12.5 mg/kg, Cu at 6.25 mg/kg, and CdMT at 0.25 mg Cd/kg. Each of the nine combinations of settings was administered to one of nine groups with six rats in each. Zn and Cu were injected sc 24 hr prior to the injection of CdMT. The concentrations of protein and Ca in urine and Ca in renal cortex were used as effects. The relationship between the experimental design settings and the effects were modeled with multiple regression. The multiple regression analysis revealed that for the high dose of CdMT (i) the enhanced values of protein in urine caused by CdMT injection could be more efficiently reduced by Zn than by Cu, and (ii) excessive Ca in urine and renal cortex could be more efficiently reduced by Cu than by Zn. No significant synergism or antagonism between Cu and Zn was found. These models can be used to estimate the dose levels of Zn and Cu which will reduce the toxic effects of CdMT. The treatment of 20.4 mg/kg Zn, for example, will reduce the effects of 0.4 mg Cd/kg as CdMT on protein in urine, and 2.8 mg/kg Cu will reduce the Ca in urine to the levels of those caused by 0.25 mg Cd/kg (no Zn and Cu). Similarly, the effect of 0.4 mg Cd/kg on Ca level in renal cortex can be reduced to that of 0.28 mg Cd/kg as CdMT by 7.98 mg Cu/kg, which is three times as efficient as Zn. The obtained results might be of importance in understanding the mechanism of cadmium toxicity and the potential risk to the health of the population exposed to cadmium occupationally or environmentally.

Animals↗
PubMed1992

Structural studies on metal-serum albumin. IV. The interaction of Zn(II), Cd(II) and Hg(II) with HSA and BSA.

There have been no detailed and reliable studies on the environment and configuration of Zn(II), Cd(II) and Hg(II) in the metal centers of human serum albumin and bovine serum albumin to date. In this paper the authentic evidence for the involvement of the cystinyl sulfur atoms in the ligation to the zinc group ions has been obtained from the X-ray photoelectron spectra. The belief that each of the zinc group ions possesses several similar binding sites in human- and bovine serum albumin and is bound to the deprotonated thiol group (-RS-) of the cysteinyl residues to form tetrahedral and linear metal centers has been further confirmed by the treatment of ligand to metal charge transfer data with Jorgensen's method. According to these results, we have inferred that these binding sites may be located at the seventeen disulfide bridges, most likely at the seven pairs of adjacent disulfide bridges between positions 75 and 567, in the serum albumins.

Animals↗
PubMed1992

Accelerated expression of cholecystokinin gene in the brain of rats rendered tolerant to morphine.

Results from behavioural studies have shown that central cholecystokinin octapeptide (CCK-8) is a powerful antagonist against opioid effects and that an increased release of central CCK-8 plays an important role in the mechanisms of tolerance to morphine analgesia. No information is available concerning the rate of biosynthesis of CCK-8 in response to chronic morphine administration. Blot hybridization experiments made in the present study revealed a marked increase in preproCCK mRNA in the brain of rats receiving chronic morphine treatment for 1, 3 and 6 days, showing an increment of 52% (p < 0.05), 62% (p < 0.05) and 97% (p < 0.01) respectively. The results suggest that an acceleration of the expression of the CCK gene during long-term morphine treatment might constitute one of the mechanisms for morphine tolerance.

Animals↗
PubMed1992

DnaK, DnaJ, and GrpE are required for flagellum synthesis in Escherichia coli.

The DnaK, DnaJ, and GrpE heat shock proteins are required for motility of Escherichia coli. Cells deleted for dnaK or dnaJ, or with some mutations in the dnaK or grpE gene, are nonmotile, lack flagella, exhibit a 10- to 20-fold decrease in the rate of synthesis of flagellin, and show reduced rates of transcription of both the flhD master operon (encoding FlhD and FlhC) and the fliA operon (encoding sigma F). Genetic studies suggest that DnaK and DnaJ define a regulatory pathway affecting flhD and fliA synthesis that is independent of cyclic AMP-catabolite gene activator protein or the chemotaxis system.

Bacterial Proteins↗
PubMed1992

[Studies and preparations of fufang danshen granules].

With the preparation of borneol-beta-cyclodextrin inclusion compound, the stability of the product was improved. In the studies on quality standards, TLC method was used in the identification of three medicinal ingredients and TLC-ultraviolet spectrophotometry was used in the content determination of the chemical constituent tanshinone II A in Salvia miltiorrhiza.

Abietanes↗
PubMed1992

[Vitrectomy combined with intravitreal injection of drugs for the management of advanced suppurative endophthalmitis].

Sixty cases (60 eyes) of advanced suppurative endophthalmitis treated by a combination of vitrectomy and intravitreal injection of drugs (antibiotics or/and corticosteroids) were investigated perspectively. Of the 60 cases, 43 were infected after trauma, 12 were infected after surgical procedures, while the others were of unknown causes. During the follow-up period of 1/2-5 years, 57 cases (95%) retained functioning eyes, the postoperative visual acuity of 34 eyes (57%) being 0.05 or better and the postoperative visual acuity of 17 eyes (28%) 0.4 to 1.0. The advantages of the therapeutic regimen are analyzed. We believe that it is the most effective therapy for suppurative endophthalmitis. The timing of the operation and the factors influencing the results are discussed. This report also presents our clinical experiences in the management of advanced suppurative endophthalmitis.

Adolescent↗
PubMed1992

Circulating endothelial cells in surgical patients.

The circulating endothelial cells (CEC) in healthy volunteers and surgical patients before and after operations were counted. The results showed that CEC counts of the patients were much higher than those of the volunteers. After operation, however, patients' CEC counts returned to control levels. It is suggested that detection of CEC may be useful for quantitatively evaluation of the injury to blood vessels in surgical patients. The operation may not only remove the source of injury, it also eliminates the injured microvascular bed which may be important to maintain homeostasis. Another possible interpretation of the results may be related to time lag and mental stress.

Blood Cell Count↗