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Biomedical subjects

D Ding

Publications and source records attributed to D Ding.

At least 73 records · Page 4Linked to original sources
PubMed1997

Quantitative relationship of carboplatin dose to magnitude of inner and outer hair cell loss and the reduction in distortion product otoacoustic emission amplitude in chinchillas.

The outer hair cells (OHCs) are thought to be the dominant source of distortion product otoacoustic emissions (DPOAEs) in the mammalian cochlea; however, little is known about the quantitative relationship between reduction in DPOAE amplitude and the degree of inner hair cell (IHC) and OHC loss. To examine this relationship, we measured the DPOAE input/output functions in the chinchilla before and after destroying the IHCs and/or OHCs with carboplatin. Low-to-moderate doses (38-150 mg/kg, i.p.) of carboplatin selectively destroyed some or all of the IHCs along the entire length of the cochlea while sparing the OHCs. Selective loss of all the IHCs had little effect on DPOAE amplitude as long as the OHCs were present. With high doses of carboplatin (200 mg/kg, i.p.), there was complete destruction of IHCs plus massive OHC loss that decreased from the base towards the apex of the cochlea. OHC loss resulted in a large decrease in DPOAE amplitude. DPOAE amplitude at 9.6 kHz decreased at the rate of 4.1 dB for every 10% loss of OHCs. At 7.2 and 4.8 kHz, DPOAE amplitude decreased 3.1 dB and 2.4 dB per 10% OHC loss, respectively. These results indicate that OHCs are the dominant source of DPOAEs.

Animals↗
PubMed1997

[Accumulation sites of kanamycin in the organ of Corti by microautoradiography].

The accumulation sites of the 3H-labelled kanamycin in the organ of Corti were observed with electron microscope. The results showed that the accumulation of kanamycin was mainly in the mitochondria, cell membrane and stereocilia of the hair cells. The possible mechanism of the kanamycin accumulation in the mitochondria is their similarity with bacteria in the protein synthesis, i.e. the way that kanamycin might inhibit the protein synthesis in the mitochondria is similar to that of bacteria. The kanamycin accumulation in the cell membrane may indicate the entrance of kanamycin into the hair cells. The kanamycin deposition in the stereocilia was most likely related to its high chemical affinity with glycocalyx.

Animals↗
PubMed1997

[Rapid functional plasticity of the neurons in the inferior colliculus and dorsal cochlear nucleus after brief exposure to intense pure tone].

The changes of response properties were observed from the single neuron in inferior colliculus (IC) and dorsal cochlear nucleus (DCN) located in the area bordering the lesion created by intense pure tone. The frequencies of traumatizing tone were chosen higher than the characteristic frequency (CF) of the neurons and beyond their excitatory response area so that the traumatizing tone would not influence the excitatory input to the neurons under study. Different types of disinhibition effects were found in more than half of the neurons after the traumatizing tone. The results indicated a subcortical origination of cortical functional reorganization and the involvement of lateral inhibition in the formation of inhibitory neural networks in both IC and DCN.

Acoustic Stimulation↗
PubMed1997

[Growth development of Ligustium chuanxiong Hort].

Experimental studies and chemical analysis have been made on Ligustium chuanxiong in its period of growth, generation and growth of organs, content and accumulation of nutritive elements, accumulation of dry matters, fertilizer consumption, etc.

Apiaceae↗
PubMed1997

[Study on polysaccharide of Lobaria kurokauae].

LOK polysaccharide is isolated from Lobaria kurokauae. By chromatography, LOK is shown to be sing substance. By gas chromatography analysis, LOK composes of rhamnose, arabinose, xylose, mannose, glucose and galactose. Their molecule ratio is about 1.00:1.34:1.12:10.13:6.99:6.47. Its mean molecule weight is estimated to be 1.5 x 10(4), its main chain is joined by a (1-->4) and a (1-->6) glucosidic linkages.

Chromatography, Gas↗
PubMed1996

An oligodeoxyribonucleotide N3'--> P5' phosphoramidate duplex forms an A-type helix in solution.

The solution conformations of the dinucleotide d(TT) and the modified duplex d(CGCGAATTCGCG)2 with N3'--> P5' phosphoramidate internucleoside linkages have been studied using circular dichroism (CD) and NMR spectroscopy. The CD spectra indicate that the duplex conformation is similar to that of isosequential phosphodiester RNA, a A-type helix, and is different from that of DNA, a B-type helix, NMR studies of model dimers d(TpT) and N3'--> P5' phosphoramidate d(TnpT) show that the sugar ring conformation changes from predominantly C2'-endo to C3'-endo when the 3'-phosphoester is replaced by a phosphoramidate group. Two-dimensional NMR (NOESY, DQF-COSY and TOCSY spectra) studies of the duplex provide additional details about the A-type duplex conformation of the oligonucleotide phosphoramidate and confirm that all furanose rings of 3'-aminonucleotides adopt predominantly N-type sugar puckering.

Base Sequence↗
PubMed1996

[A study on the mechanism of severe hypoxemia associated with acute unilateral atelectasis in dogs].

OBJECTIVE: To study the mechanism of severe hypoxemia associated with acute unilateral atelectasis (AUA). METHODS: Six dogs with acute left side atelectasis were studied during the period of rest and exercise. The pulmonary shunt and PaO2 were measured at different levels of ventilation of right lung. RESULTS: After the left side ateloctasis during resting condition, the right lung could compensate to produce only mild hypoxemia (PaO2 9 kPa). But with further increased ventilation by exercise the shunt increased (from 19% to 29%) and led to severe hypoxemia (PaO2 8 kPa). When an artificial pneumothorax was instituted on the left lung, the shunt decreased (from 29% to 18%) and PaO2 increased (from 8 kPa to 9 kPa). CONCLUSIONS: After AUA, whether severe hypoxemia would occur is determined by the volume of ventilation of the normal side lung. The excess increase of ventilation of the normal side lung by any reason may result in severe hypoxemia.

Animals↗
PubMed1996

[Expression of cytokines in labial gland of Sjögren's syndrome].

OBJECTIVE: To explore the role of cytokines in the process of inflammation and destruction of minor salivary gland in Sjögren's Syndrome. (SS) METHODS: Using in situ non-isotope double hybridization method, we detected the mRNA of the following cytokines: TNF alpha, IL-1 beta, IL-6, PDGF alpha and PDGF beta in 24 labial gland biopsied sections. RESULTS: No cytokine could be detected in the normal labial glands sections. The positivity of all cytokine expression was higher in the pSS and sSS patients than that in the control. The intensity of TNF alpha expression was 3-4 fold increase in pSS compared with sSS. The different cytokines were expressed with the different grade of lymphocytic focus. The site of different cytokines was also expressed differently. The coexpression of mRNA of TNF alpha and IL-1 beta or TNF alpha and IL-6 was only seen in the inflammatory mononuclear cells but not others. The expression of TNF alpha in aciniar cells could occur earlier than the infiltration of lymphocytes in the interstitial region. It was found that the IL-6 positive group had higher positivity of serum ANA compared with the IL-6 negative group according to Ridit statistical analysis (P < 0.05). The serum anti-SSA and anti-SSB antibody had an increase tendency in the IL-6 positive group. CONCLUSION: We hypothesize that the development of SS may be secondary to some trigger agents, which activated the aciniar cells in exocrine gland of predisposed individuals. The activated acini cells secreted TNF alpha, then TNF alpha induced other cytokine expression, followed by the lymphocytes infiltration, which led to autoimmne reaction and the destruction of the exocrine gland.

Cytokines↗
PubMed1995

[Effect of Cladonia alpestris on Trichomonas vaginalis in vitro].

In this paper, an experimental research is reported on the effect of water extract of Cladonia alpestris and S-(-) usnic acid on Trichomonas vaginalis in vitro. The results showed that both the water extract of Cladonia alpestris and S-(-)usnic acid exhibited a strong effect against Trichomonas vaginalis in vitro. As the time of action of the agents was prolonged, the mortality of Trichomonas vaginalis increased. For S-(-) usnic acid, 0.4 mg/ml was the lowest effective concentration against Trichomonas vaginalis in vitro. No remarkable differences were found in the effect of the S-(-)usnic acid and metronidazole at concentrations of 0.4 mg/ml and 0.6 mg/ml.

Animals↗
PubMed1995

[Accumulation sites of kanamycin in cochlear basal membrane cells].

The dissection technique of cochlear basal membrane, the fractional technique of tissular homogenization, and the radiometry technique were used to study the toxicity of kanamycin on the hair cells. It was found that after the cochlea was perfused with a 0.25% perilymph solution of kanamycin, there were 3.14 fg KM in a nucleus, 7.61 fg KM in a mitochondria and 21.16 fg KM in a lysosome. It showed that after entering the cell, KM mainly accumulated with in the mitochondria. Simultaneously the lysosome also phagocytized a lot of kanamycin. The germicidal mechanism of kanamycin is to inhibit the synthesis of protein in bacteria and the mitochondria has the same way of protein synthesis, the mitochondria can combine with kanamycin specifically; the drug in lysosome may be related to its phagocytic function.

Animals↗
PubMed1994

Mitochondrially encoded 16S large ribosomal RNA is concentrated in the posterior polar plasm of early Drosophila embryos but is not required for pole cell formation.

In a molecular screen for polar-localized RNAs in Drosophila, we identified the mitochondrially encoded 16S large ribosomal RNA (16S RNA) as an RNA that is highly concentrated at the posterior pole of early embryos. This high posterior accumulation decreases sharply during the first hour of embryogenesis and reaches the uniform level found throughout the remainder of the embryo by the time pole cells form 1.5 hr after fertilization. At the cellular blastoderm stage the 16S RNA is uniformly distributed basal to the nuclei of all somatic cells and is present only at low levels in the pole cells and in the apical regions of the somatic cells. Transcripts produced by the 12S small rRNA gene are also concentrated in the posterior polar plasm and exhibit the same dynamic changes in distribution as the 16S RNA. In contrast, NADH dehydrogenase subunit 1 RNA, which is transcribed from the same strand of the mitochondrial genome just downstream of the 12S and 16S genes, does not exhibit a high posterior concentration but is uniformly distributed throughout early embryos. Posterior localization of 16S RNA is normal in embryos produced by mothers carrying mutations which affect posterior patterning without disrupting the polar plasm or polar granule integrity. However, posterior localization of 16S RNA is abolished in embryos produced by females carrying maternal-effect mutations that disrupt the posterior polar plasm and the polar granules. Ectopic localization of the oskar RNA to the anterior pole of the oocyte and early embryo results in anterior assembly of polar plasm and anterior budding of functional pole cells. We show that 16S and 12S RNAs are not concentrated at the anterior pole of such embryos. This leads to the conclusion that, although the 16S and 12S RNAs are concentrated in the posterior polar plasm during normal development, functional pole cells can form in the absence of high levels of these RNAs. These data argue against previous hypotheses that the 16S RNA serves an obligatory function in pole cell formation.

Animals↗
PubMed1994

The 5' flanking region of the serotonin 2 receptor gene directs brain specific expression in transgenic animals.

The neuron is the predominant cell type expressing the serotonin 2 (5-HT2) receptor in the central nervous system. Transcriptional control elements involved in the restriction of 5-HT2 receptor gene expression to neuronal cells and tissues were studied using both transgenic mice and cultured cells. Sequences extending from a site near the translational initiation codon to -5.6 kb in the 5' flanking region of the murine receptor gene were found to be sufficient to target gene expression to the brain in transgenic animals. In transient transfection experiments a basal promoter was identified which was functional in both neuronal and nonneuronal cells. Upstream of the basal promoter two repressor domains were found within the 5' flanking sequence of the receptor gene. These sequences repressed gene activity in all cells except cells of neuronal origin, thus the repressor domains are the primary determinants to generate neuronal cell-specific transcription of the 5-HT2 receptor gene.

Animals↗
PubMed1994

Spatially regulated expression of retrovirus-like transposons during Drosophila melanogaster embryogenesis.

Over twenty distinct families of long terminal direct repeat (LTR)-containing retrotransposons have been identified in Drosophila melanogaster. While there have been extensive analyses of retrotransposon transcription in cultured cells, there have been few studies of the spatial expression of retrotransposons during normal development. Here we report a detailed analysis of the spatial expression patterns of fifteen families of retrotransposons during Drosophila melanogaster embryogenesis (17.6, 297, 412, 1731, 3S18, blood, copia, gypsy, HMS Beagle, Kermit/flea, mdg1, mdg3, opus, roo/B104 and springer). In each case, analyses were carried out in from two to four wild-type strains. Since the chromosomal insertion sites of any particular family of retrotransposons vary widely among wild-type strains, a spatial expression pattern that is conserved among strains is likely to have been generated through interaction of host transcription factors with cis-regulatory elements resident in the retrotransposons themselves. All fifteen families of retrotransposons showed conserved patterns of spatially and temporally regulated expression during embryogenesis. These results suggest that all families of retrotransposons carry cis-acting elements that control their spatial and temporal expression patterns. Thus, transposition of a retrotransposon into or near a particular host gene-possibly followed by an excision event leaving behind the retrotransposon's cis-regulatory sequences-might impose novel developmental control on such a host gene. Such a mechanism would serve to confer evolutionarily significant alterations in the spatio-temporal control of gene expression.

Animals↗
PubMed1993

Different genetic requirements for anterior RNA localization revealed by the distribution of Adducin-like transcripts during Drosophila oogenesis.

The proteins encoded by polar-localized mRNAs play an important role in cell fate specification along the anteroposterior axis of the Drosophila embryo. The only maternally synthesized mRNA known previously to be localized to the anterior cortex of both the oocyte and the early embryo is the bicoid mRNA whose localization is required to generate a homeodomain protein gradient that specifies position along the anteroposterior embryonic axis. We have identified and characterized a second mRNA that is localized to the anterior pole of the oocyte and early embryo. This mRNA encodes a Drosophila homolog of mammalian adducin, a membrane-cytoskeleton-associated protein that promotes the assembly of the spectrin-actin network. A comparison of the spatial distribution of bicoid and Adducin-like transcripts in the maternal-effect RNA-localization mutants exuperantia, swallow, and staufen indicates different genetic requirements for proper localization of these two mRNAs to the anterior pole of the oocyte and early embryo.

Amino Acid Sequence↗
PubMed1993

Localized RNAs and their functions.

The eukaryotic cell is partitioned by membranes into spatially and functionally discrete subcellular organelles. In addition, the cytoplasm itself is partitioned into discrete subregions that carry out specific functions. Such compartmentation can be achieved by localizing proteins and RNAs to different subcellular regions. This review will focus on localized RNAs, with a particular emphasis on RNA localization mechanisms and on the possible biological functions of localization of these RNAs. In recent years, an increasing number of localized RNAs have been identified in a variety of cell types among many animal species. Emphasis here will be on localized RNAs in the most intensively studied systems-Drosophila and Xenopus eggs and early embryos.

Animals↗