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Biomedical subjects

C Zhao

Publications and source records attributed to C Zhao.

At least 235 records · Page 13Linked to original sources
PubMed1994

Identification of a new member of the protegrin family by cDNA cloning.

The porcine leukocyte protegrins are a family of cysteine-rich antimicrobial peptides the primary structures of which combine features of defensins and tachyplesins. We cloned three protegrins from porcine bone marrow mRNA by PCR, including one (PG-4) that was previously unknown. The 691 bp protegrin cDNAs were > 98.8% identical, and each was surrounded by highly conserved 5' and (in some instances) 3' sequences present in structurally dissimilar antimicrobial and LPS-binding peptides of animal leukocytes.

Amino Acid Sequence↗
PubMed1994

Effect of selenium deficiency on type I 5'-deiodinase.

The type I iodothyronine 5'-deiodinase (5'-DI) present in rat liver and kidney has recently been demonstrated to be a selenoprotein. The goal of the present study was to examine in detail the effect of selenium (Se) deficiency on 5'-DI at the protein and mRNA levels. In weanling rats fed a selenium-deficient (Se(-)) diet for 6 weeks, 5'-DI activity was decreased 91 and 69% relative to control activities in liver and kidney, respectively. Administration of 3,5,3'-triiodothyronine resulted in a 2-fold increase in 5'-DI activity in control animals, but had little or no effect on 5'-DI activity in Se(-) animals. Western analysis using a specific antiserum directed against a bacterial fusion protein containing the carboxyl-terminal half of the 5'-DI protein demonstrated that this decrease in 5'-DI activity in Se(-) animals was explained by a marked decrease in 5'-DI protein. Administration of Se to Se(-) animals resulted in parallel increases in 5'-DI protein and activity over a 72-h time period. It was also shown that selenium deficiency was accompanied by a 40% decrease in 5'-DI mRNA levels in the kidney, but not in the liver. In both tissues, the administration of 3,5,3'-triiodothyronine resulted in increased 5'-DI mRNA levels which were not altered by selenium status. These studies indicate that selenium deficiency decreases 5'-DI activity by decreasing the amount of 5'-DI protein. The mechanism of this impairment in enzyme synthesis appears to be a defect in translation, presumably due to a block in the UGA-directed selenocysteine incorporation in selenium deficiency.

Animals↗
PubMed1994

A novel protein, CSG2p, is required for Ca2+ regulation in Saccharomyces cerevisiae.

Nineteen mutants that lost the ability to grow in 100 mM Ca2+ (but remained insensitive to 50 mM Sr2+) were identified in a screen of approximately 60,000 mutagenized yeast colonies. Cells carrying mutations in the CSG2 gene grow normally in low Ca2+ medium but have decreased growth rates when the Ca2+ concentration is above 10 mM. The csg2 mutant cells accumulate much higher levels of Ca2+ in a compartment that is exchangeable with extracellular Ca2+ but the nonexchangeable Ca2+ pool which predominates in wild-type cells is not influenced. Sr2+ influx is not increased in the csg2 mutant cells. Mg2+ decreases the amount of Ca2+ in the non-exchangeable pool without influencing the csg2-induced exchangeable Ca2+ pool. The data indicate that the csg2 mutation causes a selective increase in Ca2+ accumulation into a pool which is distinct from the vacuolar pool. The CSG2 protein consists of 410 amino acids, contains nine putative transmembrane segments, four potential sites for N-linked glycosylation, and a sequence with homology to the EF-hand Ca(2+)-binding site.

Amino Acid Sequence↗
PubMed1994

Overexpression and characterization of recombinant human fusion protein IL-6/IL-2 (CH925).

An expression vector encoding the human recombinant fusion protein interleukin 6/interleukin 2 (IL-6/IL-2) was constructed. When a flexible linker had been synthesized and ligated with the IL-2 gene fragment by polymerase chain reaction (PCR) amplification, the IL-6 gene fragment was unidirectionally inserted into the upstream of the linker-IL-2 sequence. The molecule of the IL-6-linker-IL-2 fusion gene named E. coli DH5 alpha/pfIL-6/2 was cloned and identified by DNA sequencing. The expressed protein named as CH925 showed a strong band on SDS-PAGE and amounted to 32% of total cell protein, and its estimated molecular weight was about 37 kDa. The fusion protein purified by gel filtration and reversed-phase HPLC showed as almost homogeneous. CH925 possesses both IL-2 and IL-6 activities when assayed by CTLL2- and 7TD1-dependent cell lines, respectively. The specific activity of IL-2 was 2.1 x 10(6) U/mg while that of IL-6 was 2.3 x 10(8) U/mg. Our studies exhibited that CH925 exerted a significant augmentative effect on the growth of erythroid colony forming units (CFU-E), and synergized with erythropoietin (EPO) and/or IL-3 in a dose-dependent way. Our experimental results also showed CH925 at a low dose causing active lymphokine-activated killer (LAK) cell proliferation more vigorous than IL-2 and/or IL-6 (p < 0.001). CH925 is a novel fusion protein, being neither IL-6 nor IL-2, more potent than IL-2 and/or IL-6 and causing non-IL-2 and non-IL-6 functions of strong EPO-like and mild IL-3-like effects on erythroid progenitor cell growth. There is a potential for efficacious clinical application of CH925.

Base Sequence↗
PubMed1994

Experimental study of the internal signal of alliesthesia induced by sweet molecules in rats.

To identify the preabsorptive signal that arouses alliesthesia, we compared the effects of five sweet molecules: glucose (3 g.5 ml-1), cyclamate (0.280 g.5 ml-1), saccharin (0.016 g.5 ml-1), aspartame (0.020 g.5 ml-1), and mannitol (3 g.5 ml-1) on the intestive aversive responses of rats. In Experiment 1, the sweet stimuli were adjusted to taste similarly sweet, and they were administered orally; they aroused similar ingestive responses. In Experiment 2, an isovolumetric load of each of the five molecules was administered in the stomach and its influence on ingestive/aversive response aroused by oral sucrose was recorded. Negative alliesthesia was obtained after gastric loads of glucose and mannitol, but not after gastric loads of cyclamate, saccharin, and aspartame.

Administration, Oral↗
PubMed1994

Cholecystokinin loses its satiating property in food deprived rats.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with oral catheters. A gustatory stimulus of 50 microliters of 1.75 mol.l-1 sucrose was injected into the mouth every 5 min during 65 min. Five minutes after the beginning of the session, 2 micrograms.kg-1 cholecystokinin (CCK) were injected IP Typical ingestive facial consummatory responses were observed in response to sweet stimuli before IP CCK. Aversive consummatory responses were observed in response to sweet stimuli after the IP CCK (negative alliesthesia). In the second part of the experiment the rats were denied access to food for 36 h and their mean body weight decreased from 426 g to 395 g. When the food deprived rats were subjected again to the same gustatory sessions, the IP CCK was not followed by negative alliesthesia in response to sweet stimuli. After recovery of initial body weights CCK was followed again by a strong negative alliesthesia. These results in rats show that the CCK mediation of duodenal satiety was hindered by body weight decrease.

Animals↗
PubMed1994

Design of orally bioavailable, symmetry-based inhibitors of HIV protease.

A series of novel inhibitors of HIV-1 protease with excellent oral bioavailability is described. Differential acylation of the two amino groups of symmetry-based diamine core groups 2-5 led to unsymmetrically substituted inhibitors 17-43, many of which inhibited HIV protease at subnanomolar concentrations. Anti-HIV activity in vitro was observed at 0.1-1 microM. A systematic evaluation of the pharmacokinetic behavior of these inhibitors in rats identified the influence of aqueous solubility, molecular size and hydrogen-bonding functionality. Compound 30 (A-80987) was selected for further evaluation based on a favorable Cmax/ ED50 ratio (> 20) and half-life (> 2 h).

Administration, Oral↗
PubMed1994

A bioassay based on recombinant DNA technology for determining selenium concentration.

The trace element selenium has recently attracted attention, particularly because (i) selenocysteine is involved in the active site of various prokaryotic and eukaryotic enzymes, some of which have a role in human health; (ii) selenocysteine incorporation into these proteins is coded by UGA codons; and (iii) as a result, selenocysteine is now considered to be the 21st amino acid in an expanded genetic code. Here, we built recombinant DNA constructs in which expression of the lac'Z gene is driven in Escherichia coli by UGA-directed selenocysteine incorporation. In this system, levels of beta-galactosidase activity are proportionally and specifically related to the presence and concentrations of several specific simple selenium derivatives. The system can thus be used as a sensitive bioassay for their determination. This bioassay is one of a few using recombinant DNA technology to provide a reporter for simple detection of a chemical trace element.

Bacterial Proteins↗
PubMed1994

Postingestive alliesthesia produced by exogenous cholecystokinin and blocked by abdominal vagotomy.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with oral catheters. A gustatory stimulus of 50 microliters of 1.75 M sucrose was injected into the mouth every 5 min during 65 min. At 5 min, 2 micrograms/kg exogenous cholecystokinin (CCK) was injected intraperitoneally. Typical ingestive facial consummatory responses were observed in response to sweet stimuli before the load. Aversive consummatory responses were observed in response to sweet stimuli after the intraperitoneal exogenous CCK (negative alliesthesia). Control intraperitoneal injection of saline was not followed by negative alliesthesia in response to sweet oral stimuli. In the last part of the experiment rats were vagotomized or underwent sham operation. When the vagotomized rats were again subjected to the same gustatory sessions, the intraperitoneal exogenous CCK was not followed by negative alliesthesia in response to sweet stimuli, whereas sham-operated rats presented a strong negative alliesthesia. These results in rats suggest that CCK mediates duodenal preabsorptive signal for alimentary alliesthesia. They also suggest that the effect is peripheral, with the vagus nerve as afferent pathway.

Animals↗
PubMed1994

[Investigation on vertigoes in childhood].

This paper analysed the pathogenesis and the vestibular test results of 87 cases of vertigo in the childhood below the age of 13 years old. 83 cases (95.4%) were vestibular peripheral lesions, and 4 cases were vestibular central lesions. 34.5% of them were benign paroxysmal vertigo and 14.9% were the Meniere's disease which all occurred at the age more than 9 years old. The appearances of ENG were semicircular canal hypofunction in 57 cases (65.5%). The function of ocular movement was abnormal in a few cases. The posturography results were compared with an age-matched control group. Posturographic recording showed length of locus and velocity increased in the thirteen patients of semicircular canal hypofunction.

Adolescent↗
PubMed1994

[Evaluation of postural sway in normals and patients with vertigoes].

A measurable parameter in the study of static equilibrium was described. The locus of postural sway was measured with a set of computer during 1 minute period in 68 normal subjects and 82 patients suffering from central and peripheral vertigoes with eyes closed. The results demonstrated: 1) There are five patterns of postural sway: centripetal, forward-backward, right-left, diffuse and multicentric patterns; centripetal pattern was the most prominent figure pattern in the normal subjects, diffuse pattern was the most prominent figure pattern in the central vertigoes. 2) Length of locus and velocity of postural sway of the patients were significantly increased in comparison with normal subjects. 3) The length of locus was the shortest and velocity of sway was the slowest in the 20-year group. There was difference between 20- year and 10-year group (P < 0.05), the difference between 20-year and 50-year was more significant (P < 0.01).

Adolescent↗
PubMed1994

Effects of lead on temporal response properties of retinal ganglion cells in developing rats.

Neonatal rats have taken in lead, during the period from their parturition to their weaning, from the milk of dams fed with water containing 0.2% lead acetate solutions. The alterations in the temporal response properties of retinal ganglion cells in adult rats (90 days) following the lead exposure at their developing stage have been studied. The results of this investigation demonstrate that the lead exposure in neonatal rats causes decreases in the optimal temporal frequency, bandwidth at half amplitude, temporal resolution and response phase of the retinal ganglion cells in adult rats. Compared with the sustained cells, the transient cells have a much greater alteration in temporal response properties.

Action Potentials↗
PubMed1993

Evaluation of the critical value of driving fatigue based on the fuzzy sets theory.

Applying the newly developed multistage evaluation method based on the fuzzy sets theory, we have evaluated the sense of driving fatigue of 8 male drivers who covered 400 km in 8 hr in the daytime, empirically revealing the distribution of the degree of driving fatigue. The critical values from "no" to "a bit" and "a bit" to "fatigued" are 1 and 5.5 hr, respectively. Finally, a tentative study of the psychophysical relations between driving time and driving fatigue has been made, leading to a curve of driving fatigue under the conditions of this experiment.

Adult↗
PubMed1993

Observation of therapeutic effect in 50 cases of chronic renal failure treated with rhubarb and adjuvant drugs.

Treatment of chronic renal failure with rhubarb and adjuvant drugs combined with other appropriate measures alleviates the suffering of the patients and improves the quality of their survival. Most patients can take care of themselves after treatment, and some can engage in half-day work. The treatment prolongs the life of the patient, and reduces medical expenses. It is of definite social and economic benefit, and conforms with China's conditions. Except for very severe cases whose blood creatinine exceeds 884 mumol/L, it can be given to all patients. It can also be used as a transitional measure before more radical therapies may be instituted.

Adolescent↗
PubMed1993

[Analysis of trace elements in scalp hair of healthy people, breast cancer and hyperplasia patients with XRF method].

The trace element analysis on the scalp hair of patients with breast cancer and hyperplasia was made using the XRF method and compared with that of healthy people. The hair samples from 42 breast cancer patients, 57 hyperplasia patients and 31 healthy people were collected respectively. The results showed that Mn, Cr and K content in the hair of the patients with cancer was much higher than that of the normal (P < 0.05). Significant differences were also found between patients with breast cancer and with hyperplasia in K and Fe content. The former was much higher than the latter (P < 0.05).

Adult↗
PubMed1992

[Determination of sugar components in wild and cultured sclerotia of Grifola umbellata (pers. ex Fr.) Pilat at different ages].

Our determination indicates that in both wild and cultured sclerotia of Grifola umbellata the contents of reducing sugar decrease with the growing years; the contents of Polysaccharide peak in the second year of growth; the contents of protein increase with the growing years; the contents of fat reaches maximum in the first year of growth; in cultured sclerotia ergosterol becomes highest in contents when the plant is two years old, while in wild sclerotia it remains lowest.

Ergosterol↗