Search PubMed⌕ Search

Biomedical subjects

Q Yang

Publications and source records attributed to Q Yang.

At least 361 records · Page 20Linked to original sources
PubMed1997

[Colour Doppler ultrasonographic indices in predicting fetal hypoxia and acidosis].

OBJECTIVE: To evaluate the effect of uterine-placental-fetal blood flow velocity waveforms (FVWs) on predicting fetal hypoxia and acidosis in high risk pregnancy. METHODS: 46 women of normal term pregnancy (normal group) and 32 women of high risk term pregnancy (high risk group) were examined with colour Doppler ultrasound for their FVWs including maternal uterine artery (UtA), fetal umbilical artery (UmA), middle cerebral artery (MCA), and renal artery (RA). Umbilical artery blood gases were analysed at delivery in high risk group. RESULTS: The resistance index (RI), pulsatile index (PI) and ratio of peak systolic to least diastolic flow velocity (S/D) of UtA, UmA and RA were higher and the PI, S/D of MCA was lower significantly in the high risk group than that of normal the group (P < 0.05). In the high risk pregnancy, when UmA PO2 was less than 2.5 kPa, the S/D of UtA, PI, S/D of UmA and RI, PI, S/D of RA were increased, and the PI of MCA was decreased (P < 0.05). There were a positive correlation between PI of UmA, RA and PO2 pH of UmA, and a negative correlation between the former and PCO2 of UmA. But there were a negative correlation between PI of MCA and PO2, pH of UmA, and a positive correlation between the former and UmA PCO2. CONCLUSION: In the high risk pregnancy, fetal cerebral blood flow increased, whereas blood flow of fetal peripheral vessels (especially renal vessel) decreases. There is a good correlation between fetal hypoxia and fetal blood FVWs. The indices of the fetal blood FVMs can identify fetal hypoxia and acidosis.

Acidosis↗
PubMed1997

Production of rhEPO with a serum-free medium in the packed bed bioreactor.

Recombinant CHO (C2) cells producing human erythropoietin (rhEPO) were cultured with DMEM:F12 media containing 5% FBS for 8-10 days in a packed bed bioreactor, then rhEPO was produced with a serum-free medium (SFM-p) which was prepared in our laboratory. The SFM-p medium can support the growth of C2 cells and the production of rhEPO, and furthermore, it easily separates rhEPO from the culture supernatant. The cell culture in a packed bed bioreactor system using SFM-p was maintained in a stable condition for 20-25 days. The expression level of rhEPO was 12-28.4 mg/L. The bioreactor productivity was 71.0 mg/L.d and increased by 12-14 fold over that of the roller bottle. The glucose consumption rate was 21 g/L.d. At the end of 30 days of perfusion circulation, a final cell density of over 3.0 x 10(7)/ml of culture volume was achieved. Since the cells were entrapped in the polyester disk, the culture supernatant contained only a few detachment cells. Variations in lactate and ammonia production in the reactor were observed, and results showed that the productions of lactate and ammonia by the bioreactor were 3.5 g/L and 5 mmol/L, respectively, and did not affect the expression of interest protein. This experiment demonstrates that SFM-p is suitable for the growth and rhEPO production of recombinant C2 in the packed bed bioreactor.

Animals↗
PubMed1997

[The effect of wuto granules on the levels of excitatory amino acids in extracellullar fluid of rat hippocampus following cerebral ischemia].

We observed the changes of excitatory amino acids (EAA) in extracellular fluid (ECLF) in rat hippocampus in case of cerebral ischemia after giving Wuto Granule compring the test groups with the control groups by microdialysis method. Results showed that there was no effect on EAA in extrcellular fluid by the drug before cerebral ischemia, but there existed staistical singnifcant changes of EAA in extracellular fluid one hour after cerebral ischemia comparing the test groups Glu and Asp with the control groups (P < 0.01). We found that there is a decrease of release of release of EAA in ECLF in case of ischemia by Wuto Granule. It could be deduced that Wuto Granule can penetrate the brain-blood barrier and this can protect the brain incse of ischemia. The application of intracerebral micrdialysis has provided a new method for the research work of pharmacology.

Animals↗
PubMed1996

Presence of S-100 beta in cholinergic neurones of the rat hindbrain.

The double staining of S-100 beta and choline acetyltransferase (ChAT) revealed that S-100 beta immunoreactivity was localized in most, but not in all, cholinergic neurones in the somatomotor nuclei of the cranial nerves and in the ambiguus nucleus. S-100 beta was present in almost all cholinergic neurones in the brain stem reticular, red, vestibular (excluding medial), mesencephalic trigeminal and cerebellar nuclei. However, S-100 beta immunoreactivity was lacking in cholinergic neurones in the parabrachial complex, the dorsal motor nucleus of the vagal nerve and most sensory nuclei. No S-100 beta-positive neurones lacked ChAT immunoreactivity. Taken together with the fact that the vulnerability of motoneurones to axotomy is markedly reduced in the first 3 postnatal weeks, during which period neuronal S-100 beta appears and increases, a possible effect of S-100 beta on the survival of cholinergic motoneurones may be suggested.

Animals↗
PubMed1996

Comparison of binding and block produced by alternatively spliced Kvbeta1 subunits.

Voltage-gated K+ (Kv) channels consist of alpha subunits complexed with cytoplasmic Kvbeta subunits. Kvbeta1 subunits enhance the inactivation of currents expressed by the Kv1 alpha subunit subfamily. Binding has been demonstrated between the C terminus of Kvbeta1.1 and a conserved segment of the N terminus of Kv1.4, Kv1.5, and Shaker alpha subunits. Here we have examined the interaction and functional properties of two alternatively spliced human Kvbeta subunits, 1.2 and 1.3, with Kvalpha subunits 1.1, 1.2, 1.4, and 1.5. In the yeast two-hybrid assay, we found that both Kvbeta subunits interact specifically through their conserved C-terminal domains with the N termini of each Kvalpha subunit. In functional experiments, we found differences in modulation of Kv1alpha subunit currents that we attribute to the unique N-terminal domains of the two Kvbeta subunits. Both Kvbeta subunits act as open channel blockers at physiological membrane potentials, but hKvbeta1.2 is a more potent blocker than hKvbeta1.3 of Kv1.1, Kv1.2, Kv1.4, and Kv1. 5. Moreover, hKvbeta1.2 is sensitive to redox conditions, whereas hKvbeta1.3 is not. We suggest that different Kvbeta subunits extend the range over which distinct Kv1alpha subunits are modulated and may provide a variable mechanism for adjusting K+ currents in response to alterations in cellular conditions.

Alternative Splicing↗
PubMed1996

IL-4 is protective against development of toxoplasmic encephalitis.

IFN-gamma is critical for prevention of development of toxoplasmic encephalitis (TE). Since IL-4 down-regulates production of IFN-gamma, we examined its role in the pathogenesis of TE in IL-4-targeted mutant (IL-4-/-) mice. IL-4-/- mice all died from 6 to 20 wk after peroral infection with cysts of the ME49 strain of Toxoplasma gondii; control mice survived. At 4 and 8 wk after infection, significantly greater numbers of T. gondii cysts and foci of acute inflammation, and greater amounts of tachyzoite-specific mRNA (by reverse-transcriptase PCR) were in brains of IL-4-/- mice than controls. Toxoplasma IgG2b and IgG3 Ab levels were slightly but significantly higher in sera of IL-4-/- than control mice, whereas IgM and IgG2a levels did not differ between these mice. Toxoplasma IgG1 and IgE Abs were not detected in sera of either strain. Amounts of IFN-gamma, TNF-alpha, IL-6, and IL-10 mRNA detected by reverse-transcriptase PCR did not differ between brains of infected IL-4-/- and controls, although brains of the former mice had greater numbers of inflammatory mononuclear cell infiltrates. IL-4 mRNA was detected only in infected control mice. Spleen cells of control mice at 8 wk after infection produced significantly greater amounts of IFN-gamma following stimulation in vitro with soluble T. gondii Ags than did those from IL-4-/- mice. These results indicate that IL-4 is protective against development of TE by preventing formation of T. gondii cysts and proliferation of tachyzoites in the brain. The impaired ability of IL-4-/- mice in the late stage of T. gondii infection to produce IFN-gamma most likely contributes to their susceptibility for development of severe TE.

Animals↗
PubMed1996

A novel murine model for the assessment of human CD2-related reagents in vivo.

CD2 is a T cell surface glycoprotein that mediates both cell-cell adhesion and transmembrane signal transduction. To construct a model for the in vivo evaluation of human (h)CD2 function and hCD2-related reagents, hCD2 transgenic mice and murine (m)CD2 knockout mice were crossed, and the F2 generation selected for mCD2-hCD2+ animals by fluorescent flow cytometry. The mCD2-hCD2+ mice are healthy and have a normal distribution of mCD3, mCD4, and mCD8 in thymus, spleen, and lymph node. Therefore expression of the hCD2 transgene does not appear to disrupt normal T cell development. The functionality of hCD2 was demonstrated by T lymphocyte proliferation upon stimulation by combined anti-CD2 plus anti-CD2R (anti-T11(2) plus anti-T11(3)) mAbs. Anti-T11(2) plus anti-T11(3) anti-human CD2 mAbs also induced proliferation of mCD2+hCD2+ F1 lymphocytes, but not mCD2+hCD2- wild-type murine lymphocytes. Either an anti-murine or the human CD2 specific (anti-T11(1)) mAbs inhibited proliferation in alloantigen, PHA, or anti-CD3 mAb stimulated cultures and inhibited only cells bearing the appropriate cognate CD2. In vivo studies of immune function yielded results consistent with these in vitro assays. Thus, anti-T11(1) mAb suppressed contact sensitivity in vivo in the transgenic/knockout mice. mCD2-hCD2+ mice treated with anti-T11(1) or LFA-3 fusion proteins also showed significant prolongation of cardiac allograft survival. This prolongation was associated both with depletion and down-modulation of CD2 on remaining T cells. These data suggest that the transgenic/knockout mice provide a useful in vivo model for the assessment of hCD2-related reagents and CD2 function, free from any potential interactions with mCD2 and mCD2 ligands.

Animals↗
PubMed1996

Intra- and extracellular immunization against HIV-1 infection with lymphocytes transduced with an AAV vector expressing a human anti-gp120 antibody.

Recently, we developed a novel anti-HIV-1 approach by transducing an anti-gp120 antibody gene into lymphocytes, resulting in the resistance to HIV-1 infection by the combined intra- and extracellular binding activities of the neutralizing antibody. To extend this study, we improved the co-expression of the heavy and light chains of the Fab105 fragment of the anti-gp120 antibody F105 by using an internal ribosome entry site (IRES) sequence. The Fab105 expression cassette was then cloned into an adeno-associated virus (AAV) shuttle vector, and encapsidated recombinant AAV-Fab105 vectors were produced. The Fab105 antibody gene was shown to be transduced into human lymphocytes by using the recombinant AAV viruses. The transduced lymphocytes were able to produce and secrete the Fab105 fragments, while maintaining their normal morphology, growth rates, and responsiveness to mitogen stimulation. The infection of several primary HIV-1 patient isolates was effectively blocked in the transduced lymphocytes. This study indicates that the combined intra- and extracellular immunization approach may be useful for the treatment of HIV-1-infected patients.

Antibodies↗
PubMed1996

Climate Change During the Last Deglaciation in Antarctica

Greenland ice core records provide clear evidence of rapid changes in climate in a variety of climate indicators. In this work, rapid climate change events in the Northern and Southern hemispheres are compared on the basis of an examination of changes in atmospheric circulation developed from two ice cores. High-resolution glaciochemical series, covering the period 10,000 to 16,000 years ago, from a central Greenland ice core and a new site in east Antarctica display similar variability. These findings suggest that rapid climate change events occur more frequently in Antarctica than previously demonstrated.

Journal Article↗
PubMed1996

Appearance of neuronal S-100 beta during development of the rat brain.

In addition to being an astroglial protein, S-100 beta is localised in distinct populations of neurons in the adult rat hindbrain. We report, here, the expression of S-100 beta in both neurons and glia of the rat brain during development. Prenatally, S-100 beta immunoreactivity was confined to glial cells close to the germinal zone. After birth, S-100 beta positive glial cells were seen mainly in the brainstem and cerebellum, while only a few were detected in cerebral cortex and hippocampus. The number of S-100 beta containing glial cells increased steadily during the first 2 postnatal weeks after which the adult pattern was attained. No S-100 beta containing neurons were present prenatally. The first S-100 beta containing neurons were seen in the mesencephalic trigeminal nucleus at postnatal day 1 (P1), and in the motor trigeminal nucleus at P3. Neuronal S-100 beta immunoreactivity in other nuclei was mostly attained from the 10th to the 21st postnatal day. The neuronal S-100 beta immunoreactivity was first detected in the cell nuclei during development, then increased in the cytoplasm with ages. A nuclear staining in many immunoreactive neurons persisted until the adult. It usually took 1 to 2 weeks for neuronal S-100 beta to attain the adult staining pattern, i.e., heavy staining of the cytoplasm and processes, after its appearance. The forebrain never contained S-100 beta positive neurons. The S-100 beta is first expressed in glial cells, suggesting it is primarily of the glial origin. Coupled with neurotrophic effects of the protein, the time course of neuronal S-100 beta expression during the critical period of neuronal development implies that it may be involved in neuronal differentiation and maturation.

Animals↗
PubMed1996

Immediate-early gene responses to different cardiac loads in the ejecting rabbit left ventricle.

Clinical and experimental observations in humans and animals have shown that different cardiac adaptations occur in response to different types of hemodynamic overload. However, very little is known about how different hemodynamic loads lead to these different cardiac adaptations. Accordingly, we studied the acute response of ejecting isolated rabbit hearts to independently varied systolic and diastolic mechanical loads at constant coronary perfusion pressure. We studied the combined effects of low end-diastolic volume (EDV) and low systolic ejection pressure (Pej), compared to low EDV and high Pej, high EDU and low Pej, and high EDV and high Pej, on the expression of c-fos, c-jun, and egr-1. Further, although we did not seek to clarify the role of these immediate-early genes in cardiac hypertrophy, we hypothesized that they should not all respond in the same manner to these different mechanical loads. In these ejecting hearts we found that the expression of these immediate-early genes did not all respond alike to the different mechanical loads: both c-fos and egr-1 were strongly induced at both 30 and 60 min. However, at 30 min only c-fos depended on the level of EDV (P = 0.01). Neither c-fos nor egr-1 was influenced by EDV at 60 min. The expression of c-jun was largely insensitive to all loading conditions. We conclude that EDV, independent of Pej, influences the pattern and time course of expression of some immediately-early genes and that these different immediate-early genes do not respond in parallel to changes in cardiac loading.

Animals↗
PubMed1996

Barefoot and in a German kitchen: federal parental leave and benefit policy and the return to work after childbirth in Germany.

"Since 1979 German federal maternity leave and benefit policy has given women incentives to stay at home and take care of their newborn and youngest children. In 1986 this leave and benefit policy was changed in several ways, turning it into a powerful instrument for delaying mothers' return to work after childbirth.... We estimate post childbirth return to work hazards for women during the federally protected leave protection period and immediately upon completion of this leave period. During the leave mothers are less likely to return to work the longer is the time left in the leave protection period; however, this result cannot be attributed generally to high levels of maternity benefits. When the leave protection period ends, mothers with strong labor force attachment who are still on leave return to their jobs."

Behavior↗
PubMed1996

In vitro and in vivo studies of three radiolabelled somatostatin analogues: 123I-octreotide (OCT), 123I-Tyr-3-OCT and 111In-DTPA-D-Phe-1-OCT.

Scintigraphy with long-acting somatostatin (SST) analogues may be useful for the localization of tumours expressing receptors (R) for SST. In this study we have analysed the in vitro and in vivo binding properties of three SST analogues, 123I-octreotide (OCT), 123I-Tyr-3-OCT and 111In-DTPA-d-Phe-1-OCT. In vitro binding studies performed with a variety of primary tumours (n=48) as well as with several tumour cell lines (A431, HT29, PANC1, COLO320, HMC1, KU812) indicated significant in vitro binding of these three radiolabelled SST analogues to two subpopulations of SSTR, high (Kd 0.2-2.0 nM) and low (Kd 5-15 nM) affinity ones. The number of SSTR on tumour cells was at least a 1000-fold higher as compared with normal peripheral blood cells. Comparative scintigraphic studies using 123I-OCT and/or 123I-Tyr-3-OCT and/or 111In-DTPA-d-Phe-1-OCT were performed in 21 patients with histologically verified intestinal carcinoid tumours. Corresponding scintigraphic results were obtained in 18 of 21 patients investigated with two different SSTR ligands, either 123I-OCT/123I-Tyr-3-OCT (four of five), 123I-OCT/111In-DTPA-d-Phe-1-OCT (eight of nine), or 123I-Tyr-3-OCT/111In-DTPA-d-Phe-1-OCT (six of seven). We conclude that various tumours express high amounts of SSTR which are recognized by three radiolabelled SST analogues: 123I-OCT, 123I-Tyr-3-OCT and 111In-DTPA-d-Phe-1-OCT. Differences between these SST analogues in their in vitro binding and/or in vivo scanning properties are observed in a minority of patients. Thus, the labelling of OCT with iodine may be an alternative approach for those nuclear medicine departments for which 111In-DTPA-d-Phe-1-OCT is not easily available, or is too expensive.

Adolescent↗
PubMed1996

Plasticity of granule cell-mossy fiber system following kainic acid induced seizures: an immunocytochemical study on neurofilament proteins.

Abnormal reestablishment of mossy fibers with the CA3 pyramidal cells and granule cells is an important aspect of postlesional plasticity in epilepsy. However, basis for the structural reorganisation and functional consequences of the event remain uncertain. Therefore we have investigated alterations of neurofilaments, major cytoskeletal components of neurons, in the rat hippocampus after the kainic acid (KA) administration, an experimental model for the temporal lobe epilepsy. The immunoreactivity for phosphorylated heavy weight neurofilament (pNFH) and non-phosphorylated heavy weight neurofilament (npNFH), in particular the pNFH, decreased in the CA1 field and inner molecular layer of the dentate gyrus during 3 and 10 days after the KA administration. After 10 days, npNFH immunoreactivity appeared in the mossy fibers, in which it is normally absent, meanwhile the pNFH staining in the mossy fibers did not decrease. From day 21, the immunoreactivity of pNFH and npNFH was normal or above normal in the CA1 stratum lacunosum-moleculare, mossy fibers, hilus and inner molecular layer of the dentate gyrus. These alterations in the later phase remained at least to day 90. The reappearance and increase of the neurofilament immunoreactivity in the inner molecular layer of the dentate gyrus probably reflects a collateral extension of the granule cell axons known as mossy fiber sprouting. The results suggest that neurofilament changes in the granule cell-mossy fiber system may be a morphological basis for the structural reconstruction of granule cell axons, and neurofilaments are involved in the plasticity after the KA induced seizures.

Animals↗
PubMed1996

Isolation and characterization of two cDNAs from Atlantic cod encoding two distinct psychrophilic elastases.

The cDNAs encoding two different Atlantic cod elastases have been isolated and sequenced. The predicted amino acid sequences revealed two preproelastases, consisting of a signal peptide, an activation peptide and a mature enzyme of 242 and 239 amino acids. Amino acid sequence identity between the two cod elastases was 60.1% and identity with mammalian elastases ranged from 50-64%. The two cod elastases contain all the major structural features common to serine proteases, such as the catalytic triad His57, Asp102 and Ser195. Both cod elastases have a high content of methionine, consistent with previous findings in psychrophilic fish enzymes.

Adaptation, Physiological↗
PubMed1996

Evaluation of automatic knowledge acquisition techniques in the diagnosis of acute abdominal pain. Acute Abdominal Pain Study Group.

Clinical diagnosis in acute abdominal pain is still a major problem. Computer-aided diagnosis offers some help; however, existing systems still produce high error rates. We therefore tested machine learning techniques in order to improve standard statistical systems. The investigation was based on a prospective clinical database with 1254 cases, 46 diagnostic parameters and 15 diagnoses. Independence Bayes and the automatic rule induction techniques ID3, NewId, PRISM, CN2, C4.5 and ITRULE were trained with 839 cases and separately tested on 415 cases. No major differences in overall accuracy were observed (43-48%), except for NewId, which was below the average. Between the different techniques some similarities were found, but also considerable differences with respect to specific diagnoses. Machine learning techniques did not improve the results of the standard model Independence Bayes. Problem dimensionality, sample size and model complexity are major factors influencing diagnostic accuracy in computer-aided diagnosis of acute abdominal pain.

Abdominal Pain↗