Search PubMed⌕ Search

Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 865 records · Page 48Linked to original sources
PubMed1993

Glial cell-specific expression of the serotonin 2 receptor gene: selective reactivation of a repressed promoter.

The 5' flanking region of the 5-HT2 receptor gene has been cloned, sequenced and its transcriptional regulatory functions analyzed. The promoter lacks an identifiable TATA motif, and utilizes at least 11 clustered start sites. Promoter function was analyzed by transient assays in rat C6 glioma cells, which were shown to express the endogenous 5-HT2 receptor gene, as well as in rat CREF and human HeLa cells which do not express the endogenous gene. The basal promoter functioned equally well in all three cell lines; and a repression domain, located upstream of the basal promoter, inhibited activity of the promoter in all three cell lines. A far upstream cell specific activator domain restored promoter activity in C6 glioma cells, but did not reactivate the silenced promoter in CREF or HeLa cells. The upstream activator domain, repressor domain and basal promoter functioned in concert to achieve cell type specific expression. The activator domain did not direct C6 glioma cell specific expression in the absence of the repressor domain or in constructs carrying a heterologous basal promoter. These results indicate that glial cell expression of the 5-HT2 receptor gene is achieved through a cell type specific reactivation of a repressed promoter.

Amino Acid Sequence↗
PubMed1993

Regulation of estrogen receptor protein and messenger ribonucleic acid by estradiol and progesterone in rat uterus.

The objective of this study was to examine the mechanisms of estrogen receptor (ER) processing and replenishment in the uterus of ovariectomized rats after estradiol and progesterone treatment. Uterine ER binding activity, ER protein and ER mRNA were measured by receptor binding exchange assay, Western blot and slot blot, respectively. The regulation of ER levels in rat uterus by estradiol and progesterone was very dramatic. Changes in ER protein were faithfully reflected by changes in binding activity. Estradiol caused receptor "processing" within 4 h of administration followed by recovery or "replenishment" of ER levels to the initial level by 20 h. The term "processing" has previously been used to describe the loss of ER binding activity in the early phase of estradiol-action, but it was never clear whether the ligand binding site was inactivated by processing or if the receptor molecule actually disappeared. This study shows that receptor "processing" constitutes disappearance of receptor protein and the later "replenishment" phase represents new ER protein rather than recycling of "processed" receptor. Progesterone-action, on the other hand, influenced only the "replenishment" phase by blocking recovery of ER protein. ER mRNA was suppressed by estradiol at 8 h, after the receptor was "processed" and "replenishment" already initiated. Progesterone, on the other hand, did not alter the steady state level of the message. Other mechanisms, such as regulation of translation rate of existing mRNA and changes in the rate of degradation of ER proteins are more likely involved in acute regulation of ER by these ovarian steroid hormones.

Analysis of Variance↗
PubMed1993

Regulated expression of testis angiotensin-converting enzyme during spermatogenesis in mice.

A unique isozyme of angiotensin-converting enzyme (ACE) is produced in large amounts by developing germ cells and is referred to as testis ACE. This protein results from the transcriptional recognition of a sperm-specific promoter during spermatogenesis. The expression within germ cells of testis ACE mRNA was studied using in situ hybridization, ribonuclease (RNase) protection, and Northern analysis. In parallel, testis ACE protein expression was measured through use of Western blot analysis and immunohistochemistry. Although testis ACE protein is first detected in step 10 spermatids, testis ACE mRNA is first detected in a developmentally younger cell population, late pachytene spermatocytes. Thus, testis ACE mRNA is translationally arrested for a period of several days until late in spermiogenesis.

Animals↗
PubMed1993

The role of the pineal in the control of the daily patterns of neurohypophysial hormone secretion.

Plasma concentrations of neurohypophysial hormones show clear rhythms over 24 hr which can be suppressed by exposure to constant light, an observation consistent with pineal involvement. A study has therefore been performed on the changes in the hormone levels in the hypothalamus, posterior pituitary, and plasma over 24 hr in control, pinealectomised, and sham pinealectomised animals to determine if the pineal could play a role. Water intake, urine excretion, packed cell volume, plasma osmolality, and electrolytes were also monitored. Pinealectomy had little effect on fluid balance, but after 8 weeks for oxytocin and 2 weeks for vasopressin the morning values (0700-0800) for the circulating concentrations of the hormones were significantly higher in the pinealectomized group compared with the combined sham operated and unoperated groups (pineal intact). By contrast, the pituitary vasopressin was significantly lower in the pinealectomised group. The increase in plasma oxytocin and vasopressin seen over the hours of daylight and accompanying fall in plasma osmolality seen in the pineal intact group were absent in the pinealectomised group. Similarly, the evening fall in pituitary hormone concentrations and increase in hypothalamic hormone content were absent in the pinealectomised animals. After 10 days of exposure to constant light, the fall in plasma osmolality in the pineal-intact animals over the day was no longer significant; instead a significant increase in plasma osmolality and sodium was seen in the pinealectomised group. Exposure to constant light, while altering the patterns of neurohypophysial activity in the pineal intact group, had little effect on the pinealectomised animals.

Animals↗
PubMed1993

Transfer of neurotoxigenicity from Clostridium butyricum to a nontoxigenic Clostridium botulinum type E-like strain.

Two Clostridium butyricum strains from infant botulism cases produce a toxic molecule very similar to C. botulinum type E neurotoxin. Chromosomal, plasmid, and bacteriophage DNAs of toxigenic and nontoxigenic strains of C. butyricum and C. botulinum type E were probed with (i) a synthesized 30-mer oligonucleotide encoding part of the L chain of type E botulinum toxin and (ii) the DNA of phages lysogenizing these cultures. The toxin gene probe hybridized to the chromosomal DNA of toxigenic strains but not to their plasmid DNA. All toxigenic and most nontoxigenic strains tested were lysogenized by a prophage on the chromosome. Prophages of toxigenic strains, irrespective of species, had related or identical DNAs which differed from the DNAs of prophages in nontoxigenic strains. The prophage of toxigenic strains was adjacent or close to the toxin gene on the chromosome. Phage DNAs purified from toxigenic strains did not hybridize with the toxin gene probe but could act as the template of the polymerase chain reaction to amplify the toxin gene. The toxin gene was not transferred between C. botulinum and C. butyricum (either direction) when different pairs of a possible gene donor and a recipient strain were grown as mixed cultures. Nontoxigenic C. butyricum or C. botulinum type E-like strains did not become toxigenic when grown in broth containing the phage induced from a toxigenic strain of the other species.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophages↗
PubMed1993

Preeclampsia is associated with abnormal expression of adhesion molecules by invasive cytotrophoblasts.

In normal human pregnancy, invasion of the uterus and its arterial system by cytotrophoblasts extends through the entire decidua and the adjacent third of the myometrium. Our previous work showed that during the first trimester of pregnancy, invasion is accompanied by a marked change in the expression of cell adhesion molecules by invasive cytotrophoblasts. In the pregnancy disorder preeclampsia, cytotrophoblast invasion is limited to the superficial decidua, and few arterioles are breached. The purpose of this study was to determine whether cytotrophoblast expression of adhesion molecules in this disorder is also abnormal. Placental bed biopsy specimens from normal pregnancies and those complicated by preeclampsia were stained with anti-integrin antibodies. The results showed that adhesion molecule switching by invasive cytotrophoblasts is abnormal in preeclampsia, which suggests that this subpopulation of trophoblast cells fails to differentiate properly. A likely result is that the delicate balance of adhesive interactions that normally permit cytotrophoblast invasion is tipped in favor of those which restrain this process, with the net effect of shallow uterine invasion.

Cell Adhesion Molecules↗
PubMed1993

A mRNA localized to the vegetal cortex of Xenopus oocytes encodes a protein with a nanos-like zinc finger domain.

mRNAs concentrated in specific regions of the oocyte have been found to encode determinants that specify cell fate. We show that an intermediate filament fraction isolated from Xenopus stage VI oocytes specifically contains, in addition to Vg1 RNA, a new localized mRNA, Xcat-2. Like Vg1, Xcat-2 is found in the vegetal cortical region, is inherited by the vegetal blasomeres during development, and is degraded very early in development. Sequence analysis suggests that Xcat-2 encodes a protein that belongs to the CCHC RNA-binding family of zinc finger proteins. Interestingly, the closest known relative to Xcat-2 in this family is nanos, an RNA localized to the posterior pole of the Drosophila oocyte whose protein product suppresses the translation of the transcription factor hunchback. The localized and maternally restricted expression of Xcat-2 RNA suggests a role for its protein in setting up regional differences in gene expression that occur early in development.

Amino Acid Sequence↗
PubMed1993

Changes in progesterone and oestrogen receptor mRNA and protein during maternal recognition of pregnancy and luteolysis in ewes.

This study characterized changes in levels of mRNA and protein for endometrial oestrogen receptors (ERs) and progesterone receptors (PRs) during luteolysis and maternal recognition of pregnancy. For cyclic and pregnant ewes, endometrium was collected on days 10, 12, 14, or 16 post-oestrus (4 ewes/day for each status) for the measurement of ER and PR mRNA and protein. The amount of receptor mRNA is expressed in relative units above background, measured from radiographs of dot-blot hybridization of total endometrial RNA with ER and PR cDNAs. At hysterectomy, jugular vein blood samples were collected and assayed for progesterone, total corpus luteum weight was recorded and, in vitro, endometrial oxytocin-stimulated inositol phosphate formation was estimated. In pregnant ewes, plasma progesterone increased gradually between days 10 and 16 (P < 0.01), corpus luteum weight was stable at approximately 0.8 g and oxytocin did not stimulate endometrial formation of inositol phosphates in vitro. In contrast, in cyclic ewes, plasma progesterone decreased from day 10 to day 16 (P < 0.01), corpus luteum weight decreased after day 14 to approximately 0.48 g (P = 0.05) and oxytocin stimulated an increase of approximately 1300% in the endometrial formation of inositol phosphates on day 16. cDNAs specifically hybridized with 1.6 and 3.1 kb transcripts for PR mRNA and a 6.5 kb transcript for ER mRNA. In cyclic ewes, the amount of PR mRNA increased from day 10 to maximum levels on days 14-16. The number of PRs decreased from day 10 (2.25 pmol/mg DNA) to day 12 (0.98 pmol/mg DNA) and then increased from day 14 to day 16 (2.8 pmol/mg DNA). In pregnant ewes, PR mRNA levels were greatest on days 10-12 and decreased by approximately 50% by day 16. In contrast, the number of PRs was relatively unchanged from day 10 to day 16 (1.53 to 1.03 pmol/mg DNA). In cyclic ewes, the amount of ER mRNA was lowest at day 10 and increased fivefold by day 16. The number of ERs remained relatively unchanged from day 10 to day 14 (6.07 pmol/mg DNA) and increased by day 16 (16.12 pmol/mg DNA). In pregnant ewes, ER mRNA decreased by approximately 80% from day 12 to day 16. Similarly, the number of ERs decreased from day 10 to day 16 (5.41 to 2.05 pmol/mg DNA). Correlations between ER mRNA and PR mRNA (r = 0.68), ERs and PRs (r = 0.50) and ER mRNA and ERs (r = 0.50) were high (P < 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Changes in progesterone and oestrogen receptor mRNA and protein and oxytocin receptors in endometrium of ewes after intrauterine injection of ovine trophoblast interferon.

This study determined whether twice-daily intrauterine injections of ovine conceptus secretory proteins (oCSP) containing type-I trophoblast interferon (25 micrograms/uterine horn) from day 11 to day 15 post-oestrus (oestrus = day 0) could alter the binding capacities of endometrial receptors for oxytocin, progesterone and oestrogen in cyclic ewes when compared with control ewes receiving serum protein (SP) injections. Injections of oCSP on days 11-15 post-oestrus decreased concentrations of oestrogen receptors (P < 0.06), oestrogen receptor mRNA (P < 0.05) and progesterone receptors (P < 0.08) in endometrium on day 16 when compared with SP-infused control ewes, which were undergoing corpus luteum regression on days 14-16. Injection of oCSP also decreased the number (P < 0.10) and affinity (P < 0.06) of oxytocin receptors. Inositol phosphate formation induced in the endometrium on day 16 by 100 nM oxytocin in vitro was highly correlated with the concentration (r > or = 0.93, P < 0.001) and Kd (r = -0.91, P < 0.01) of oxytocin receptors in SP-infused ewes, but was not as highly correlated with concentration (r < or = 0.83, P < 0.06) and Kd (r < or = 0.40, P > 0.40) of oxytocin receptors in oCSP-infused ewes. This indicates that oCSP disrupted the relationship between oxytocin receptor binding and oxytocin-induced activation of its second messenger system. These results indicate that antiluteolytic type-I trophoblast interferon may prevent oxytocin-induced luteolytic pulsatile secretion of prostaglandin F2 alpha during maternal recognition of pregnancy in sheep, by reducing the synthesis and affinity of endometrial oxytocin receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Electroacupuncture accelerated the expression of c-Fos protooncogene in dopaminergic neurons in the ventral tegmental area of the rat.

The mesolimbic dopaminergic system has been implicated in mediating morphine and electroacupuncture analgesia. In the present study, Fos immunoreactivity was used as a marker of neuronal activity to investigate if electroacupuncture could activate the dopaminergic neurons in the midbrain. Electroacupuncture stimulation significantly increased the number of Fos-positive dopaminergic neurons in the ventral tegmental area (VTA), whereas no significant c-fos expression in the dopaminergic neurons was observed in the substantia nigra (SN). These results indicate that the VTA rather than the SN may play a role in mediating electroacupuncture analgesia.

Acupuncture Analgesia↗
PubMed1993

Induction of c-fos expression in the rostral medulla of rats following electroacupuncture stimulation.

The present study was designed to examine the induction of c-fos mRNA and Fos-like protein in the rostral medulla of awake rats following electroacupuncture (EA) stimulation, using in situ hybridization and immunohistochemical method. Rats were subjected to EA stimulation (100 Hz, 1-2-3 mA) for 30 min by inserting two needles into acupoints Zusanli (S36) and Sanyingjiao (Sp6) of each hind leg. Animals were sacrificed 1h and 2h after EA for in situ hybridization and immunohistochemical study, respectively. c-fos mRNA or Fos-like-immunoreactivity (FLI) neurons were densely distributed in the rostral ventromedial medulla (RVM), including raphe magnus nucleus, gigantocellular reticular nucleus, gigantocellular reticular nucleus alpha, as well as intermediate reticular nucleus. Neurons in the solitary tract nucleus also showed c-fos expression. The results suggest that the RVM may be an important region for mediating EA effect.

Afferent Pathways↗
PubMed1993

The beta-thalassemia frameshift at codon 8 (-AA) observed in four Chinese of the Uygur nationality.

During a survey for beta-thalassemia in Kashi City, Xinjiang Province, P.R. China, four unrelated Uygur students were identified as heterozygotes for the beta-thalassemia frameshift at codon 8 (-AA). Detection was with the polymerase chain reaction combined with allele-specific oligonucleotide hybridization. This beta-thalassemia allele has not been observed in the Chinese population before and might be rather specific for the Uygur nationality.

Asian People↗
PubMed1993

[Separation and identification of stimulants and their metabolites].

Forty-one stimulant drugs banned by the International Olympic Committee were studied after they were administered to human volunteers. The parent drugs and their metabolites in free or conjugated forms in human urine collected within 24 hours after administration of the drugs were extracted, separated and identified. The separation was performed on a capillary gas chromatograph with nitrogen-phosphorous detector, while the identification was achieved on a capillary gas chromatograph with mass-selective detector. The extract was injected into the gas chromatograph both directly and after derivatization with trifluoroacetic anhydride (TFAA) or N-methyl-N-trimethylsilyl trifluoroacetamide (MSTFA) as well as TFAA and MSTFA combined. The conjugated metabolites were studied after acid hydrolysis of the extract and then selectively derivatized as above. The results are summarized in 4 tables in the text.

Central Nervous System Stimulants↗
PubMed1993

Three RFLPs defining a haplotype associated with the common mutation in human medium-chain acyl-CoA dehydrogenase (MCAD) deficiency occur in Alu repeats.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a common inborn error of fatty-acid oxidation and may cause sudden infant death. Previous studies revealed that (i) homozygosity for an A-to-G mutation at nucleotide 985 of the mRNA coding region (A985G) is an extremely common cause of MCAD deficiency and (ii) MCAD deficiency is strongly associated with a particular haplotype for RFLPs for BanII, PstI, and TaqI. TaqI allele 2 is always associated with the A985G mutation in human MCAD deficiency. In this study, we have delineated the molecular basis of the RFLPs for PstI, BamHI, and TaqI in the human MCAD gene. Our results prove that the three RFLPs are caused by point mutations in the 8 kb of DNA encompassing exons 8-10 of the human MCAD gene. The TaqI polymorphism is caused by a C-to-A substitution 392 bp upstream of the exon 8, and the PstI and BamHI polymorphisms are due to T-to-C and G-to-A substitutions, respectively, which are 727 and 931 bp downstream of exon 10 respectively. All three RFLPs lie within Alu repetitive sequences. Comparison of intronic sequences immediately following exon 10 from two normal individuals with different haplotypes showed that this region contains densely packed Alu repeats and is highly polymorphic. Our results are consistent both with a founder effect as the cause of the high prevalence of a single (A985G) mutation in MCAD deficiency and with its association with a particular haplotype for these intragenic RFLPs.

Acyl-CoA Dehydrogenase↗
PubMed1993

Synthesis and expression in Escherichia coli of a human neutrophil activating protein-1/interleukin-8 gene.

The complete gene coding for human neutrophil activating protein-1/interleukin-8 was synthesized using a semi-chemical semi-enzymatic method. The synthetic gene was then overexpressed in Escherichia coli under the temperature-regulated control of the PRPL tandem promoters. As determined by SDS-PAGE and densitometry, the overexpressed protein comprised up to 18.5% and 10.9% of the total soluble protein in E. coli cells grown in shake flasks and in batch fermentation, respectively. The recombinant NAP-1/IL-8 was then purified to > 95% homogeneity by gel filtration and cation exchange chromatography. The purified protein appeared as a single band on the SDS-PAGE gel and possessed potent chemotactic activity in the concentration of < 10 ng/ml, as assayed by the agarose plate method. An early skin reactivity was also observed when the pure NAP-1/IL-8 was injected subcutaneously into the rabbits. The N-terminal 36 amino acid sequence of the recombinant NAP-1/IL-8 was determined using the Edman method and was shown to be identical to that of the native protein.

Animals↗
PubMed1993

Experimental research on treatment of hypertension with acupuncture.

The effects of acupuncture on blood pressure, microcirculation of bulbar conjunctiva and hemorheology in spontaneous hypertensive rats (SHRs) were observed. The mechanism of acupuncture to lower blood pressure is discussed from the viewpoint of microcirculation and hemorheology. SHRs and Wistar rats of both sexes weighing about 250g were divided into three groups: 1. Acupuncture group of 15 SHRs, in which Quchi (LI 11) and Taichong (Liv 3), Hegu (LI 4) and Zusanli (St 36) were selected and punctured twice a day with the needle retained for 15 minutes and the reducing method by twisting and twirling the needle used, 15 days constituting a course; 2. Control group of 10 SHRs; 3. Control group of 10 normal Wistar rats. All rats in groups 2 and 3 were treated in the same way as in Group 1 except for the acupuncture. It was found that the morphology and blood flow of bulbar conjunctiva microcirculation in SHRs were obviously abnormal: the capillaries with blood flow were reduced in number, the arterioles were spasmodic and of smaller diameter, the venules were dilated due to blood stasis which showed a slow granular flow of blood, the blood viscosity was increased, hematocrit increased, and the time for RBC electrophoresis prolonged. The blood was in a state of high viscosity, high concentration and high aggregation. After acupuncture treatment the blood pressure not only fell, but the morphology and blood flow of bulbar conjunctiva microcirculation and the hemorheology of SHRs all improved remarkably.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Therapy↗