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Biomedical subjects

D Zhou

Publications and source records attributed to D Zhou.

At least 199 records · Page 11Linked to original sources
PubMed1997

The morphology and connections of neurons in the gasping centre of adult rats.

Neuronal activities in the intermediate reticular nucleus and adjacent lateral tegmental field are critical for the neurogenesis of the ventilatory pattern of gasping. We report herein the anatomical features of these neurons, their axonal projections and the location of neurons providing afferent inputs. These neuroanatomical evaluations were performed by iontophoretic injection of the tracer Neurobiotin into the region of the intermediate reticular nucleus of the rat. At the site of injection, neurons having soma of 30-50 microns were filled. Labelled axons and terminals were observed in ipsilateral regions which contain neurons having established functions in the control of ventilatory activity. These regions include the nucleus ambiguous and motor nuclei of the hypoglossal and facial nerves. In addition, axonal projections extended to the contralateral region of the intermediate reticular nucleus. From this contralateral region, retrograde tracing revealed projections to the site of injection. Similarly, many ipsilateral regions which received axonal terminals from the region of the intermediate reticular nucleus had reciprocal projections to this region. These anatomical results support the physiological observation that the neurogenesis of gasping involves a synchronized activation of diverse components of the brainstem ventilatory control system.

Animals↗
PubMed1997

Isolation of new bioactive annonaceous acetogenins from Rollinia mucosa guided by liquid chromatography/mass spectrometry.

Reversed-phase high-performance liquid chromatography (RP-HPLC) fractionation, monitored by liquid chromatography/electrospray mass spectrometry (LC/ESI-MS), led to the isolation of two new bioactive annonaceous acetogenins, rollidecin C (1) and rollidecin D (2), from the bioactive aqueous methanol fraction of the leaves of Rollinia mucosa (Annonaceae). The structures were confirmed by analyses of the 1H and 13C NMR data. In addition, a known adjacent bis-tetrahydrofuran (THF) acetogenin, desacetyluvaricin (3), was isolated from this plant for the first time utilizing the LC/ESI-MS monitoring approach. Compound 1 exhibited selective cytotoxicity toward the colon tumor cell line (HT-29), while 2 showed only borderline cytotoxicity in a panel of six human tumor cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Screening for Annonaceous acetogenins in bioactive plant extracts by liquid chromatography/mass spectrometry.

The Annonaceous acetogenins are amenable to analysis by liquid chromatography/mass spectrometry (LC/MS) using the electrospray positive-ion mode. Under conditions of atmospheric pressure in-source collision-induced dissociation (APICID), the acetogenins reproducibly provided characteristic ion patterns and fragment ions. Accordingly, the presence of these biologically interesting acetogenins and other derivatives in plant extracts and chromatographic fractions can be readily detected by analyzing selected ion chromatograms. LC/MS screening of a bioactive crude methanol-soluble fraction of Rollinia mucosa detected the presence of some 40 known acetogenins in this plant extract, in addition to four new acetogenins of diverse structure. This rapid and relatively uncomplicated selected ionization procedure should also prove suitable for the screening of many other structural families of natural products.

4-Butyrolactone↗
PubMed1997

Influence of olfactory bulbectomy and subsequent imipramine treatment on 5-hydroxytryptaminergic presynapses in the rat frontal cortex: behavioural correlates.

1. Alterations of 5-hydroxytryptaminergic mechanisms are thought to play a special role in the pathogenesis of depression and antidepressant treatments are assumed to restore these changes. 2. We have used one of the most reliable models of depression, the olfactory bulbectomized rat to study the long term consequences of this manipulation and of subchronic imipramine treatment on two parameters of 5-hydroxytryptaminergic presynapses, 5-hydroxytryptamine (5-HT) transporter density and tryptophan hydroxylase apoenzyme concentration, in the frontal cortex as well as on active avoidance learning several weeks after bulbectomy. 3. The Bmax value of [3H]-paroxetine binding and the concentration of the 5-HT synthesizing enzyme were both significantly elevated in the frontal cortex of bulbectomized rats compared to sham-operated controls. 4. Imipramine treatment, either by daily injections or by subcutaneous implantation of slow release imipramine-containing polymers reduced the elevated tryptophan hydroxylase apoenzyme levels in the frontal cortex of bulbectomized, but not of sham-operated control rats and restored the deficient learning performance of bulbectomized rats. 5. Both effects were more pronounced after continuous drug administration by imipramine-releasing polymers compared to daily i.p. injections. 6. These findings indicate that bulbectomy leads to a compensatory 5-hydroxytryptaminergic hyperinnervation of the frontal cortex. Chronic antidepressant treatment seems to attenuate the increased output of the 5-hydroxytryptaminergic projections in the frontal cortex through the destabilization of the rate limiting enzyme of 5-HT synthesis of the 5-hydroxytryptaminergic nerve endings in this brain region.

Adrenergic Uptake Inhibitors↗
PubMed1997

Developmental and environmental regulation of tissue- and cell-specific expression for a pea protein farnesyltransferase gene in transgenic plants.

Farnesylation mediates membrane targeting and in vivo activities of several key regulatory proteins such as Ras and Ras-related GTPases and protein kinases in yeast and mammals, and is implicated in cell cycle control and abscisic acid (ABA) signaling in plants. In this study, the developmental expression of a pea protein farnesyltransferase (FTase) gene was examined using transgenic expression of the beta-glucuronidase (GUS) gene fused to a 3.2 kb 5' upstream sequence of the gene encoding the pea FTase beta subunit. Coordinate expression of the GUS transgene and endogenous tobacco FTase beta subunit gene in tobacco cell lines suggests that the 3.2 kb region contains the key FTase promoter elements. In transgenic tobacco plants, GUS expression is most prominent in meristematic tissues such as root tips, lateral root primordia and the shoot apex, supporting a role for FTase in the control of the cell cycle in plants. GUS activity was also detected in mature embryos and imbibed embryos, in accordance with a role for FTase in ABA signaling that modulates seed dormancy and germination. In addition, GUS activity was detected in regions that border two organs, e.g. junctions between stems and leaf petioles, cotyledons and hypocotyls, roots and hypocotyls, and primary and secondary roots. GUS is expressed in phloem complexes that are adjacent to actively growing tissues such as young leaves, roots of light-grown seedlings, and hypocotyls of dark-grown seedlings. Both light and sugar (e.g. sucrose) treatments repressed GUS expression in dark-grown seedlings. These expression patterns suggest a potential involvement of FTase in the regulation of nutrient allocation into actively growing tissues.

Alkyl and Aryl Transferases↗
PubMed1997

Cloning and characterization of a rhamnogalacturonan hydrolase gene from Botrytis cinerea.

Rhamnogalacturonan hydrolase (Rgase A) cleaves alpha 1--2 linkages between rhamnosyl and galacturonosyl residues in pectin. A 1.9 kb RGase A cDNA clone (BCRHGA) was isolated from a B. cinerea cDNA library using a PCR-amplified Aspergillus aculeatus RGase A probe. It's 1.7 kb open reading frame had 62% identity at the amino acid level with A. aculeatus RGase A. Northern blots of B. cinerea total RNA probed with BCRHGA revealed a 2 kb band, suggesting the cDNA clone is full or nearly-full length. To determine mRNA expression of the gene, B. cinerea was grown in media containing 0.5% apple pectin, 0.5% rhamnogalacturonan-I and 1% glucose carbon sources. Northern analysis revealed the BCRHGA gene was expressed on all carbon sources, but with different patterns of expression. B. cinerea RGase A appeared to be coded for by a single or low copy number gene based on Southern analysis.

Amino Acid Sequence↗
PubMed1997

Homozygous delta 32 deletion of the CCR-5 chemokine receptor gene in an HIV-1-infected patient.

BACKGROUND: Recent research has found that entry of non-syncytium-inducing (NSI), monocyte-macrophage-tropic HIV-1 isolates requires binding to both CD4 and CCR5 receptors, and that delta 32/delta 32 homozygous individuals are protected against infection. OBJECTIVE: To analyse the polymorphism of CCR-5 gene in HIV-1-infected and uninfected subjects. DESIGN AND METHODS: CCR-5 sequences were amplified by polymerase chain reaction (PCR) from DNA of peripheral blood mononuclear cells. Samples from 152 HIV-1-infected subjects and 122 uninfected controls were tested for the detection of the 32 base-pair deletion. HIV-1 phenotype was determined by viral isolation and MT-2 evaluation. RESULTS: The wild-type/delta 32 heterozygous and delta 32/delta 32 homozygous conditions were represented in 10.7 and 0.8% of healthy controls and in 9.8 and 0.7% of HIV-1-infected subjects, respectively. Of note, the delta 32/delta 32 deletion of the CCR-5 gene was detected by PCR and sequencing confirmed in a patient with progressive infection harbouring a clade B virus with SI phenotype. CONCLUSIONS: delta 32/delta 32 homozygosity for the CCR-5 gene does not confer absolute protection against HIV-1 infection, suggesting that either macrophage-tropic viral strains could use coreceptors other than CCR-5 or infect independently of the presence of a functional CCR-5 coreceptor. Alternatively, primary infection sustained by T-cell-tropic isolates, although exceptional, may occur.

Adult↗
PubMed1997

Adenosine A3 receptor expression and function in eosinophils.

The A3 adenosine receptor is widely expressed in human tissues with the most abundant expression in the lung and liver, but the predominant cellular localization and functions of this receptor in humans are unknown. Since adenosine influences the activation of circulating and resident inflammatory cells within the lung and leads to exaggerated airway narrowing in individuals with inflammatory airway disorders, we hypothesized that A3 receptor gene expression is localized to inflammatory cells and that gene expression is upregulated in airway inflammation. Lung and airway tissue were obtained at thoracotomy from nonsmoking subjects and subjects with inflammatory airway disorders associated with tobacco smoke or asthma. In situ hybridization identified A3 receptors in mesenchymal cells and eosinophils within the lamina propria of the airways and the adventitia of blood vessels, but not in mast cells. A3 receptor transcripts were highly expressed in peripheral blood eosinophils purified from atopic donors (6.36 +/- 0.60 pg/microg total RNA) in comparison with neutrophils (0.26 +/- 0.06 pg/microg) or mononuclear cells (0.9 +/- 0.15 pg/microg). Mean A3 receptor transcript abundance was greater in lung tissue from subjects with airway inflammation (0.33 +/- 0.04 pg/microg total RNA) than in normal lung (0.24 +/- 0.03 pg/microg total RNA, P = 0.035). The A3 receptor agonist N6-(4-amino-3-iodobenzyl)adenosine dose-dependently inhibited platelet activating factor-induced eosinophil chemotaxis to a maximum of 41%. This inhibitory effect was completely abolished by addition of the A3 receptor selective antagonist 3-(3-iodo-4-aminobenzyl)-8-(4-oxyacetate)phenyl-1-propylxanthine. We conclude that A3 receptors are primarily expressed on eosinophils in human lung, where they mediate inhibition of eosinophil chemotaxis. Specific A3 receptor ligands may be useful agents in the treatment of eosinophil-dependent diseases such as asthma and rhinitis.

Adenosine↗
PubMed1997

[Mast cells of ileocecal junction in irritable bowel syndrome].

To investigate whether the mast cells (MC) of the ileocecal junction (ICJ) is elevated in the irritable bowel syndrome (IBS) and the possible roles of the MC in IBS, the biopsies of ICJ were stained specifically by histochemistry for the MC in the IBS group (n = 20) and the normal group (n = 19). The structure relation between MC and nerves was studied through an electronic microscopy and an immunohistochemical method demonstrating neuronspecific enolase. The results demonstrated that the number of the MC of ICJ was significantly elevated in the IBS (P = 0.019) and that mast cells were close to nerves which were often unmyelinated nerves in lamina propria. The results indicate that the MC of ICJ may be responsible for the pathophysiology of the IBS. We conclude that the MC of ICJ may be a mediator between the gut and the nervous system in the IBS, and that the mast cell stabilizer or the antagonists of the mast cell products may have potential treatment effects on the IBS.

Adult↗
PubMed1997

[The evaluation of endoscopic biliary drainage for 288 patients with malignant hilar obstruction].

Hilar tumors are extremely difficult to manage with a considerably lower resection rate. We performed endoscopic biliary drainage for 288 patients with hilar tumors (Klatskin tumor 184, gallbladder carcinoma 23, HCC 47 and other metastases 34) in the past 3 years. 162 patients underwent endoscopic nasobiliary drainage, 80 plastic biliary stenting, and 46 expandable metal stent implantation. 4 patients were given double stents insertion simultaneously, 43.1% of patients received good drainage with the total effective rate of 67.0%, but postprocedure cholangitis took place in 13.8% of patients within one month and 3 died of cholangitis and sepsis. In the long-term follow-up patients without surgical treatment, the median sruvival was 5.3 months. The outcome was closely related to Bismuth types, and jaundice could be relieved if more than about 40% of the liver was drained. The double stents for the left and right intrahepatic duct in the meantime could enlarge drainage area and improve the theraputic effectiveness. To get highest benefit, the 3 endoscopic biliary drainage methods should be choosen properly and exchanged flexibly. We conclude that endoscopic biliary drainage is a safe and useful management for the hilar tumor and should be the treatment of choice for palliating jaundice in the inoperable patients.

Adolescent↗
PubMed1997

[Total knee replacement in diabetic patients].

From December 1987 to March 1995, 16 TKRs were performed for 9 diabetic patients at our department. 7 of them had rheumatoid arthritis (RA), and 2 osteoarthritis (OA). There were 1 male and 8 females. The average age was 55.9 years (range 49-69 years), and the average weight was 64.5 kg (range 54-78 kg). According to the hospital for special surgery (HSS) knee rating scale, the pre and postoperative evaluations were made. The HSS scores were improved after the operation from average 30.2 points preoperatively to 78.2 points postoperatively. The excellent and good rate was 94%. After 3.9 years follow-up (range 10 months to 8 years), the HSS score was 74.4 points, and the rate of excellent and good was 87.5%. Compared to the other 209 RA or OA patients with 287 TKR at the same period, the HSS score was almost the same, but the infection rate was higher (3.5%). We conclude that the TKR of diabetic patients could also get the similar results as common patients if the patients are under the good control of glycemia and medical treatment.

Aged↗
PubMed1997

[Properties of adherence of erythrocytes to endothelial cells in patients with ischemic stroke].

Adherence of erythrocytes to human umbilical vein endothelial cells (HUVEC) in patients with cerebral thrombosis and transient ischemic attack (TIA) were quantitatively studied in the flow chamber system, compared with that in healthy subjects. We found: (a) The adherence of erythrocytes to HUVEC in patients with cerebral thrombosis and TIA increased, compared with that in healthy subjects; (b) The adhesion of erythrocytes to HUVEC in patients with TIA was not significantly different from that of patients with cerebral thrombosis. These suggested that the increased adhesion of erythrocytes to endothelial cells might play an important role in the pathologic process of ischemic stroke.

Aged↗
PubMed1997

[Adhesion of erythrocytes of patients with transient ischemic attack to injured endothelial cells].

Adherence of erythrocytes of patients with transient ischemic attack(TIA) to human umbilical vein endothelial cells(HUVEC) treated with H2O2 were quantitatively studied in the flow chamber system. The results showed that injured HUVECs enhanced the adherence of erythrocytes to endothelial cells in patients with TIA. The increased adhesion of erythrocytes to endothelial cells might promote the vascular damage. Consequently endothelium might play an important role in the increased adhesiveness of TIA RBC to endothelial cells.

Aged↗
PubMed1997

Combined effect of noise and vibration on articulation of Chinese syllable.

To study combined effect of noise and vibration on articulation, changes of the speech features of Chinese single syllabic utterances were investigated under combined factors. The experiments were conducted under four conditions: combined noise and vibration, simple noise, simple vibration and control. A set of signal processing system was established, programs for speech signal analysis and statistics were developed. The results showed that, as compared with simple noise , simple vibration or control condition, the fundamental frequency, energy and duration of articulation under combined conditions increased significantly. It suggests that the effect of noise and vibration should be considered in the design of aerospace speech recognition system.

Aerospace Medicine↗
PubMed1997

A membrane skeleton that clusters nicotinic acetylcholine receptors in muscle.

We have presented ultrastructural and semiquantitative immunofluorescence evidence to support the idea that AChR are clustered in rat myotubes by virtue of their ability to associate with a spectrin-based membrane skeleton. Many of the interactions postulated to be involved in the formation of this skeleton, and in the anchoring of AChR to it, must still be examined at the biochemical level, but the overall similarity of this structure to that of the human erythrocyte is already clear. The ability of different members of the spectrin superfamily to associate in various combinations to form distinct plasmalemmal domains provides some exciting hints as to how the surface membrane can be organized efficiently to subserve multiple purposes. One of the challenges of future research will be to learn how innervation regulates the assembly of the membrane skeleton at the developing NMJ, and how this structure is altered as the junction matures. Another will be to learn if the principles of neuromuscular synaptogenesis are relevant to interactions between neurons in the brain, where cells must distinguish between multiple synaptic inputs and assemble synaptic structures at thousands of distinct sites on the neurolemma. Members of the spectrin superfamily have been identified in synaptic structures in the central nervous system (e.g., Carlin et al., 1983; LeVine and Sahyoun, 1986; Malchiodi-Albedi et al., 1993), so much of what we have learned at the neuromuscular junction may be applicable to central synapses.

Animals↗
PubMed1997

Gene regulation studies of aromatase expression in breast cancer and adipose stromal cells.

The expression of aromatase in human breast tumors was studied using the reverse transcription-polymerase chain reaction (RT-PCR) method on 70 breast tissue specimens. An RT-PCR analysis using two oligonucleotide primers derived from 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 revealed that exons I.3 and PII are the two major exons I 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 (ASCs). Recently, the regulatory properties of a 696-base pair region that contains promoter II, and is situated immediately upstream of exon II of the human aromatase gene, were investigated. Detailed DNase 1 footprinting analysis, DNA mobility shift assays, and chloramphenicol acetyltransferase (CAT) functional studies of this genomic region were performed and led to the identification of a segment (B1) that could act as a promoter (probably promoter I.3) in adipose stromal and breast cancer cells. The study further revealed that the B1 region could be divided into two domains which were designated RE1 and RE2. RE1 was found to have the promoter activity, and RE2 was found to regulate the promoter activity of RE1, but in different manners in MCF-7 cells (as an example of breast cancer cells) and in ASCs. RE2 was found to function as a positive regulatory element in MCF-7 cells and as a negative regulatory element in ASCs, respectively. It was also found that in several breast cancer cell lines, including MCF-7, the promoter activities of both promoter II and promoter I.3 were found to be suppressed by a negative regulatory element, a silencer, present in the 162 bp fragment which is located upstream from promoter II and downstream from promoter I.3. The precise position of the silencer element (termed S1) was localized by deletion mutation and DNase 1 footprinting analysis, and the silencing activity of S1 on promoter I.3 (in B1 fragment) was confirmed by CAT plasmid transfection experiments. UV crosslinking experiments are being performed to examine the regulatory proteins interacting with the silencer element. These studies serve as the basis for the further characterization of the regulatory mechanism of aromatase expression in human breast cancer and ASCs.

Adipose Tissue↗
PubMed1997

[The research and application of uroflow rate measuring].

Using A/D converter acquiring uroflowrate is introduced in this paper. The uroflowrate curve is analysed and displayed by computer in real time. The programming of uroflowrate curve smoothing is presented.

Electronic Data Processing↗