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Biomedical subjects

D Zhou

Publications and source records attributed to D Zhou.

At least 235 records · Page 13Linked to original sources
PubMed1996

Aromatase gene expression and its exon I usage in human breast tumors. Detection of aromatase messenger RNA by reverse transcription-polymerase chain reaction.

The expression of aromatase in human breast tumors has been studied by the reverse-transcription polymerase chain reaction (RT-PCR) method on 70 breast tissue specimens. An RT-PCR analysis using two oligonucleotide primers derived from the exon II of the human aromatase gene revealed that aromatase mRNA was detected in all but three tissue specimens. Furthermore, primer-directed RT-PCR was performed to determine the exon I usage in aromatase mRNA in these breast tumor specimens. The analysis has revealed that exons I.3 and PII are the two major exon Is present in aromatase mRNA isolated from breast tumors, suggesting that promoters I.3 and II are the major promoters driving aromatase expression in breast cancer and surrounding adipose stromal cells. The RT-PCR analysis also detected two products, I.3A (334 bp in length) and I.3B (222 bp in length), when it was carried out using a primer derived from exon I.3 and a reverse primer derived from exon II. The nucleotide sequences of these products have been determined and indicate that I.3A contains a region which was previously thought to be an intron. In addition, RT-PCR analyses of RNA isolated from eight pairs of breast tumor and neighboring normal tissue specimens were performed to evaluate the exon I usage and the distribution of I.3A- and I.3B-containing aromatase RNA messages in breast tumor and neighboring normal tissues. The results suggest that I.3B- and I.3A-containing messages are mainly present in breast tumor and neighboring normal tissues, respectively. Finally, the exon I/promoter usage for aromatase expression in eight cell lines (skin fibroblast, MCF-7, MDA-MB-231, T-47D, SK-BR-3, JAR, OVCAR-3, and human adipose stromal cells) was examined by primer-directed RT-PCR analyses. These studies provide a basis for further evaluation of the control mechanism of aromatase expression and estrogen biosynthesis in breast tumors.

Adipose Tissue↗
PubMed1996

Serotonin transporters in the rat frontal cortex: lack of circadian rhythmicity but down-regulation by food restriction.

Molecular biological findings have indicated that the affinity and the density of presynaptic serotonin transporters may be subject to adaptive regulation, but the physiological conditions that may act to trigger such changes are presently unknown. By means of [3H]paroxetine binding to rat cortical membranes, we studied the influence of two physiological variables that are clearly associated with altered serotonergic activity--circadian rhythm and semistarvation--on K(D)and Bmax values of the serotonin transporter of the rat frontal cortex. No circadian fluctuations of both parameters were observed. Also, semistarvation (50% reduction of normal voluntary food intake) for 2 days had no effect on either K(D) or Bmax values of cortical [3H]paroxetine binding. Food restriction for either 7 days or 2 weeks, however, resulted in a significant, approximately 30%, reduction of the density of cortical serotonin transporters with unchanged transporter affinity. These findings indicate that long-term changes in the density of cortical serotonin transporters can be induced by long-lasting alterations of certain environmental variables. Because the duration and the radius of action of presynaptically released serotonin are governed by the efficiency of the reuptake mechanism, such adaptive changes of serotonin transporter density must be expected to cause long-term alterations of the modulatory impact of the central serotonin system on certain brain functions.

Animals↗
PubMed1996

The pathogenesis of gonococcal urethritis in men: confocal and immunoelectron microscopic analysis of urethral exudates from men infected with Neisseria gonorrhoeae.

Confocal and immunoelectron microscopic analysis of urethral exudates from 12 men with gonococcal urethritis showed that Neisseria gonorrhoeae can invade urethral epithelial cells. Studies with acridine orange stain demonstrated that the majority of organisms within urethral epithelial cells were viable at the time of fixation. Three-dimensional modeling of an infected epithelial cell using image analysis of 21 digitized confocal sections stained with YOYO-1 and DiIC 18(3) revealed that gonococcal invasion of these cells occurred in a polar fashion, most likely at the epithelial luminal surface. Serial immunoelectron micrographs showed evidence of membrane fusion with pedestal formation between the gonococcus and the epithelial cell, gonococci within vacuoles, and occasional gonococci free in the cytoplasm. Immunoelectron microscopy studies showed ruptured vacuoles at the cell surface releasing organisms. These studies demonstrate that urethral epithelial cells are invaded by gonococci during the course of infection in males.

Epithelium↗
PubMed1996

Reduction of intracellular glutathione levels produces sustained arterial narrowing.

OBJECTIVE: Although lipid peroxidation and alterations in endogenous antioxidants have been hypothesized to contribute to cerebral vasospasm after subarachnoid hemorrhage, there has been no direct evidence demonstrating the relationship between oxidative stress and delayed arterial narrowing. To elaborate the role of the endogenous intracellular antioxidant and electron exchanger glutathione (GSH) in cerebral vasospasm, rat femoral arteries were treated with perivascular application of I-buthionine-(SR)-sulfoximine (BSO), which inhibits the synthesis of GSH. METHODS: To determine the dose-response relationship, BSO at doses of 10 to 100 mg/ml, in platelet-rich plasma, was applied for 7 days to rat femoral arteries in vivo. Vessels were then perfusion-fixed for morphometric analysis of luminal cross-sectional area. To determine the time course of arterial narrowing, BSO (75 mg/ml) was applied to femoral arteries for 1, 3, 7, or 21 days before histological analysis, as described above. With rats treated with 50 to 100 mg/ml BSO, exogenous GSH (100 mg/kg) was administered, by intraperitoneal injection, daily for 7 days. To demonstrate the mechanism of BSO effects in smooth muscle cells (SMCs), cultured rat aortic SMCs were treated with 1 mmol/l BSO for 24 hours and assayed for intracellular levels of GSH and two products of lipid peroxidation, malondialdehyde and 4-hydroxyalkenal. RESULTS: Compared with control arteries treated with platelet-rich plasma alone, perivascularly administered BSO applied for periods of 1 to 21 days produced sustained and reversible narrowing of rat femoral arteries with a time course, severity, and histological appearance analogous to those observed after perivascular application of whole blood. BSO-induced arterial narrowing was dose-dependent, with 60% reductions in the luminal cross-sectional area being noted at 75 and 100 mg/ml (P < 0.005). Systemic administration of exogenous GSH slightly inhibited the effect of BSO on arterial narrowing, although the inhibition was not statistically significant. Cultured rat aortic SMCs exposed to BSO for 24 hours showed a 70% decrease in intracellular GSH levels (P = 0.03); levels of two products of lipid peroxidation, malondialdehyde and 4-hydroxyalkenal, were increased by 25% (P = 0.24) and 38% (P = 0.09), respectively. CONCLUSION: These data support the hypothesis that diminished intracellular levels of GSH may produce delayed chronic arterial narrowing after subarachnoid hemorrhage. The specific mechanism by which GSH levels modulate vasoconstriction remains uncertain but may involve endogenous antioxidant capacity in SMCs.

Animals↗
PubMed1996

Protein farnesyltransferase in plants: molecular characterization and involvement in cell cycle control.

Farnesylation is required for membrane targeting, protein-protein interactions, and the biological activity of key regulatory proteins, such as Ras small GTPases and protein kinases in a wide range of eukaryotes. In this report, we describe the molecular identification of a plant protein farnesyltransferase (FTase) and evidence for its role in the control of the cell cycle in plants. A pea gene encoding a homolog of the FTase beta subunit was previously cloned using a polymerase chain reaction-based strategy. A similar approach was used to clone a pea gene encoding a homolog of the FTase alpha subunit. The biochemical function of the pea FTase homologs was demonstrated by the reconstitution of FTase enzyme activity using FTase fusion proteins coexpressed in Escherichia coll. RNA gel blot analyses showed that levels of FTase mRNAs are generally higher in tissues, such as those of nodules, that are active in cell division. The relationship of FTase to cell division was further analyzed during the growth of suspension-cultured tobacco BY-2 cells. A biphasic fluctuation of FTase enzyme activity preceded corresponding changes in mitotic activity at the early log phase of cell growth. Moreover, manumycin, a specific inhibitor of FTase, was effective in inhibiting mitosis and growth in these cells. Using synchronized BY-2 cells, manumycin completely blocked mitosis when added at the early S phase but not when added at the G2 phase. These data suggest that FTase is required for the plant cell cycle, perhaps by modulating the progression through the S phase and the transition from G1 to the S phase.

Alkyl and Aryl Transferases↗
PubMed1996

Interleukin 6 modulates interleukin-1-and stress-induced activation of the hypothalamic-pituitary-adrenal axis in male rats.

This study examined the interaction between interleukin 6 (IL-6) and IL-1 and between IL-6 and stress on the activation of the hypothalamic-pituitary-adrenal (HPA) axis. Coadministration of IL-6 (100 ng/rat) with IL-1 (20 or 100 mg/ rat) resulted in synergistic stimulation of the HPA axis, as determined by increased plasma levels of ACTH and corticosterone (CORT) which were greater in rats that received both cytokines than in rats receiving either cytokine alone. Concomitant administration of IL-6 (100 ng/rat) with exposure to a novelty stressor also synergistically stimulated the activation of the HPA axis, as IL-6-treated rats subjected to novelty stress had greater increases in plasma levels of ACTH and CORT than vehicle-treated rats exposed to novelty stress or rats receiving IL-6 alone. However, concomitant administration of IL-6 (100 ng/rat) did not significantly affect restraint stress induced elevation of plasma levels of ACTH and CORT, although IL-6 tended to prolong restraint stress induced elevation of plasma levels of CORT. These findings indicate a modulatory role for IL-6 stimulated HPA axis activity in response to IL-1 or a novelty psychological stressor, but not for restraint stress.

Adrenal Glands↗
PubMed1996

The relationship of fluorosis and brick tea drinking in Chinese Tibetans.

Brick tea-drinking fluorosis is an unusual environmental problem. As a result of an investigation of tea-drinking habits, total fluoride intakes, dental fluorosis, and skeletal fluorosis, this disease has been found in the Sichuan Province of China in Tibetans with a long history of drinking brick tea. The dental fluorosis investigation of 375 Tibetan children (213 males, 162 females) and 161 Han children (86 males, 75 females), 8-15 years of age, was carried out in Daofu County, Sichuan Province. According to the standard of the Chinese Health Ministry, a skeletal fluorosis survey of 658 Tibetans (264 males, 394 females) and 41 Hans (20 males, 11 females), all over 16 years old, was performed. The total fluoride intake and fluorosis were determined from a question--calculation method in all participants. The morbidities of dental fluorosis in Tibetan and Han children are 51.2% and 11.05%, respectively, and the indexes of dental fluorosis are 1.33 and 0.17 (chi 2 = 75.7, p < 0.01) respectively. The morbidity of skeletal fluorosis is 32.83% for Tibetan children and zero for the Han children. The fluoride intakes of Tibetan children and adults were 5.49 mg/person/day and 10.43 mg/person/day, respectively, in this area. Of total everyday fluoride intake, 94.2% by children and 94.4% by adults was from brick tea and zanba (r = 0.99).

Adolescent↗
PubMed1996

Simultaneous bilateral total knee arthroplasty for rheumatoid arthritis.

OBJECTIVE: To study the result of one staged bilateral total knee arthroplasty (TKA) operation under epidural anesthesia on patients with severe rheumatoid arthritis (RA). METHODS: From April 1987 to December 1992, simultaneous bilateral TKA was performed on 45 patients (90 knees), including 41 patients with RA, 3 with juvenile RA, and 1 with Sjogren syndrome. The mean follow-up period was 63 months. RESULTS: Improved function and pain relief were noted in all patients. There were no wound healing problems. Thrombophlebitis was observed in few cases. Late infection rate was 5.6% (5 knees) and aseptic loosening was revised on 5 knees. CONCLUSIONS: Simultaneous bilateral TKA is not only a procedure of low cost, saving blood, reducing anesthesia risk, drugs' side effect and hospitalization, but also facilitates early rehabilitation. Except for late infection, there is no increase in complications.

Adult↗
PubMed1996

[Antibody-targeted radio-chemotherapy of human primary liver cancer with radio-iodinated AFP monoclonal antibodies conjugated with mitomycin C: a preliminary clinical observation].

A "dual-warhead missile" made of 131I-AFP monoclonal antibody conjugated with mitomycin C was prepared. Twelve patients with moderately advanced and advanced primary liver cancer (PLC) were treated by i.v. injection of the antibody preparation. Tumor decrease in size was observed in 45.5% of the treated patients and decline in serum AFP level was seen in 83.3%. The one-year survival rate was 45.5%. Antibody-targeted radio-chemotherapy is a treatment of choice for advanced PLC patients.

Adult↗
PubMed1996

[Effects of pentoxifylline on leukocyte adhering to endothelial cell].

Using flow chamber, we quantitatively studied the effects of pentoxifylline on normal leukocytes adhering to cultured human umbilical vein endothelial cells. The results showed that pentoxifylline reduced the adhesive number of leukocytes to endothelial cells by acting mainly on leukocytes. The mechanism may be that pentoxifylline inhibits the adherence caused by oxygen free radicals from the leukocytes.

Cell Adhesion↗
PubMed1996

[The serum MBP, myelin sheath immunohistochemistry and electromicroscope of expetrimental epilepsy rats].

We detected the level of myelin basic protein (MBP) in the serum of experimental epilepsy rats using simplified MBP ELISA, and the myelin sheaths of their brain with MBP immuno-histochemistry (IHC) and transmitted electronmicroscopy (TEM) in order to explore the relation of brain myelin sheaths and MBP to the pathogenic mechanism of epileptic seizure. The results show that the serum MBP level in the experimental epilepsy group is significantly higher than that in the control groups (P < 0.05), and is similar to that in some patients with generalized myoclonic seizures reported by us previously. The IHC and TEM findings in the brain of epilepsy rats indicate that the lamelliform structure of myelin sheaths in some part of hippocampus region becomes relaxing, disorderly and homogenized. Our studies imply that epileptic seizures are associated with MBP release from the subtle damaged regions of myelin sheaths during epileptic seizures, and the change of MBP component in myelin sheath may play and important role in the pathogenesis of epilepsy.

Animals↗
PubMed1996

[A study on the changes of DCC and MCC genes in colorectal carcinoma and adenoma].

Both deleted in colorectal carcinoma (DCC) and mutated in colorectal carcinomas (MCC) genes are newly found tumour suppresser genes in colorectal carcinomas. In this study mutations of DCC gene and loss of heterozygosity (LOH) of MCC gene were detected with Southern blot and PCR methods respectively. The study consisted of 30 cases of colorectal adenoma (10 with mild, 10 with moderate and 10 with severe dysplasia) and 33 cases of colorectal carcinomas (13 highly, 10 moderately and 10 poorly differentiated, meanwhile 9 in Dukes A, 10 in B and 14 in C stage). Their paired normal colorectal mucosa served as control. The results were as follows: mutation of DCC was not found in any specimen with normal mucosa or with adenoma of mild and moderate dysplaaia, while it was found in one if those with severe dysplasia. Mutation of DCC was, however, found in 7 of the 33 specimens with carcinoma and there was a correlation between the positive rate and the differentiation or staging of the carcinoma. LOH of MCC was not found in normal mucosa, but it was found in 2/10, 3/10 and 4/10 of the adenoma specimens with mild, moderate and severe dysplasia respectively. 18/33 of the carcinoma specimens was found to have LOH of MCC and there was also a correlation between the positive rate and the differentiation or staging of the carcinoma. These results suggest that the frequency of multiple gene changes increase with poor differentiation and increased staging of colorectal carcinoma.

Adenoma↗
PubMed1996

[Study on small intestinal lumenal and membrane flora of 30 healthy Chinese].

Lumenal and membrane flora were investigated using ileum and jejunum samples obtained through endoscopy. 10 kinds of representative anaerobic or aerobic bacteria were cultured for quantitative and qualitative analysis. The result showed there were significant differences between lumenal and membrane flora on Clostridium of ileum, Lactobacillus and Bacillus bifudus in jejunum (P < 0.05). Enterococci were not found in all of these 30 patients. In jenumum, E. Coli was found in 53.3% (16/30) of lumenal flora and 33.3% (10/30) of membrane flora, Bacteroides were found in 40.0% (12/30) of lumenal flora and 33.3% (10/30) of membrane flora respectively.

Adolescent↗
PubMed1996

[A direct transnasal transsphenoidal approach to pituitary tumors].

38 cases of pituitary adenomas were resected via direct transnasal trans-sphenoidal approach. Complete or subtotal tumor excision was achieved in 36 patients, and partial excision in 2. The operative mortality was 0. The operative techniques were, in patients with small nostrile, a 5-6 mm small incision was made in the base of lateral alar, but the speculum straightly upon to the anterior wall of the sphenoidal sinus. As expanding the speculum, the middle septum was pressed to the opposite side. Under the operating microscope, the anterior wall mucose was dissected away, the bony wall drill off and then the sphenoidal sinus approached. Other steps were as usual. All cases achieved good result. The advantages of this approach were less destructive, less time-concuming, less complications and easy to perform.

Adenoma↗
PubMed1996

[Furosemide test for diagnosis of endolymphatic hydrops: a clinical exploration].

Furosemide test (FT) is a clinical method for the diagnosis of endolymphatic hydrops (EH). Immediately preceding i.v. injection of 20 mg furosemide, a caloric test was performed with 50 micromilligrams of water at 30 degrees C. Nystagmography was employed to measure the maximum slow velocity of caloric nystagmus. The test was repeated one hour after the injection. The two sets of data were then compared. An increase beyond 22.97% was defined as positive. The first group was composed of 54 patients of EH as the experimental group, and the second group 54 patients with vertigo of non-EH as control. The positive rates of the two groups were 70.4% and 25.9% respectively. It showed that FT was useful for detecting EH. The percentage of directional preponderance (DP) was obviously descended in the two groups after i.v. furosemide. Descending rate was 77.8% (21/27) in the first group, which had reached the normal value in 9 cases. It was showed that DP was important also for criticizing FT. The hearing of all subjects was not damaged. When the renal function of the subject was normal and not combined with the use of aminoglycoside antibiotics, the dose of FT was not dangerous to the hearing and had few side reactions. The mechanism of dehydration in hydropic labyrinth was presumed to be acute systemic diuresis, but the effect in inner ear was unknown.

Diagnosis, Differential↗
PubMed1995

Cyclic nucleotide phosphodiesterase type IV participates in the regulation of IL-10 and in the subsequent inhibition of TNF-alpha and IL-6 release by endotoxin-stimulated macrophages.

We have recently shown that PGE2 inhibits the release of TNF-alpha from LPS-stimulated murine peritoneal macrophages via a feedback mechanism involving IL-10. Here we demonstrate that a rolipram-sensitive phosphodiesterase (PDE) type IV participates in the regulation of IL-10 synthesis. Selective PDE IV inhibitors (rolipram and RO-20-1724), but not selective inhibitors of other types of PDE, significantly augment marcrophage IL-10 production and contribute to the inhibition of TNF-alpha and IL-6 release. The addition of rolipram to LPS-stimulated macrophages results in the accumulation of cAMP and in the significant augmentation of IL-10 release. Competitive PCR analysis reveals that the drug dramatically increases IL-10 mRNA, but does not affect TNF-alpha mRNA. The inhibitory effect of rolipram on TNF-alpha can be significantly but incompletely reversed by anti-IL-10 Ab, whereas the effect of the drug on IL-6 can be completely reversed by anti-IL-10. In endotoxemic mice, the administration of rolipram increases serum IL-10 and reduces TNF-alpha and IL-6 levels. Northern blot analysis of spleens from these mice shows that rolipram increases IL-10 mRNA, whereas TNF-alpha mRNA remains largely unchanged. These results suggest that a rolipram-sensitive PDE type IV is involved in the production of IL-10 and in turn contributes to the inhibition of TNF-alpha and IL-6 release.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1995

Phosphatidic acid and lysophosphatidic acid induce haptotactic migration of human monocytes.

The present study was aimed at defining the chemotactic activity of phosphatidic acid, which is rapidly produced by phagocytes in response to chemotactic agonists. Exogenously added phosphatidic acid induced human monocyte directional migration across polycarbonate filters with an efficacy (number of cell migrated) comparable to that of "classical" chemotactic factors. In lipid specificity studies, activity of phosphatidic acid decreased with increasing acyl chain length but was restored by introducing unsaturation in the acyl chain with the most active form being the natural occurring 18:0,20:4-phosphatidic acid. Lysophosphatidic acid was also active in inducing monocyte migration. No other phospholipid and lysophospholipid tested was effective in this response. Monocyte migration was regulated by a gradient of phosphatidic acid and lysophosphatidic acid bound to the polycarbonate filter, in the absence of detectable soluble chemoattractant. Migration was also observed if phospholipids were bound to fibronectin-coated polycarbonate filters. Thus, phosphatidic acid and lysophosphatidic acid, similarly to other physiological chemoattractants (e.g. C5a and interleukin-8), induce cell migration by an haptotactic mechanism. Phosphatidic acid caused a rapid increase of filamentous actin and, at higher concentrations, induced a rise of intracellular calcium concentration. Monocyte migration to phosphatidic acid and lysophosphatidic acid, but not to diacylglycerol, was inhibited in a concentration-dependent manner by Bordetella pertussis toxin, while cholera toxin was ineffective. In the chemotactic assay, phosphatidic acid and lysophosphatidic acid induced a complete homologous desensitization and only partially cross-desensitized one with each other, or with diacyl-glycerol and monocyte chemotactic protein-1. Suramine inhibited monocyte chemotaxis with a different efficiency phosphatidic acid > lysophosphatidic acid" diacyl-glycerol On the contrary, monocyte chemotactic protein-1-induced chemotaxis was not affected by the drug. Collectively, these data show that phosphatidic acid induces haptotactic migration of monocytes that is at least in part receptor-mediated. These results support a role for phosphatidic acid and lysophosphatidic acid in the regulation of leukocyte accumulation into tissues.

Actins↗