Biomedical subjects

M Shao

Publications and source records attributed to M Shao.

At least 19 recordsLinked to original sources

PubMed2006

Maturation of firing pattern in chick vestibular nucleus neurons.

The principal cells of the chick tangential nucleus are vestibular nucleus neurons participating in the vestibuloocular and vestibulocollic reflexes. In birds and mammals, spontaneous and stimulus-evoked firing of action potentials is essential for vestibular nucleus neurons to generate mature vestibular reflex activity. The emergence of spike-firing pattern and the underlying ion channels were studied in morphologically-identified principal cells using whole-cell patch-clamp recordings from brain slices of late-term embryos (embryonic day 16) and hatchling chickens (hatching day 1 and hatching day 5). Spontaneous spike activity emerged around the perinatal period, since at embryonic day 16 none of the principal cells generated spontaneous action potentials. However, at hatching day 1, 50% of the cells fired spontaneously (range, 3 to 32 spikes/s), which depended on synaptic transmission in most cells. By hatching day 5, 80% of the principal cells could fire action potentials spontaneously (range, 5 to 80 spikes/s), and this activity was independent of synaptic transmission and showed faster kinetics than at hatching day 1. Repetitive firing in response to depolarizing pulses appeared in the principal cells starting around embryonic day 16, when <20% of the neurons fired repetitively. However, almost 90% of the principal cells exhibited repetitive firing on depolarization at hatching day 1, and 100% by hatching day 5. From embryonic day 16 to hatching day 5, the gain for evoked spike firing increased almost 10-fold. At hatching day 5, a persistent sodium channel was essential for the generation of spontaneous spike activity, while a small conductance, calcium-dependent potassium current modulated both the spontaneous and evoked spike firing activity. Altogether, these in vitro studies showed that during the perinatal period, the principal cells switched from displaying no spontaneous spike activity at resting membrane potential and generating one spike on depolarization to the tonic firing of spontaneous and evoked action potentials.

2-Amino-5-phosphonovalerate↗

PubMed2006

A frequent partial AZFc deletion does not render an increased risk of spermatogenic impairment in East Asians.

The gene families in the AZFc region of the Y chromosome have been shown to be functionally important in human spermatogenesis. The gr/gr deletion, a partial AZFc deletion that reduces the copy numbers of all the AZFc gene families, was identified as a significant risk factor for spermatogenic impairment in Dutch, Spanish and Italians. However, the presence of this deletion in healthy French and Germans questioned its importance in male infertility. In this study, we have shown that the gr/gr deletion does not render an increased risk in Han Chinese. In fact, the gr/gr deletion is frequent (about 8%) in our survey of 886 East Asians from 8 ethnic groups. Furthermore, the DAZ1/DAZ2 deletion has been detected as the primary subtype of the gr/gr deletion in East Asians, though this doublet has been considered as crucial for normal spermatogenesis in Europeans. The different spermatogenic effects of various types of the partial AZFc deletion suggest that the functional difference between AZFc gene copies is a likely cause of inconsistent associations of the gr/gr deletion with spermatogenic impairment across populations.

Base Sequence↗

PubMed2005

Secretory expression of recombinant proteins in an attenuated Vibrio anguillarum strain for potential use in vaccines.

Vibrio anguillarum is an important bacterial fish pathogen responsible for epizootics in both marine and freshwater fish worldwide. Studies on pathogenic V. anguillarum has shown that its virulence is mediated by a 65 kb endogenous pJM1-like plasmid, which encodes an efficient iron uptake system. The plasmid-free derivative of wild V. anguillarum was found to be greatly attenuated and elicited a good protection against wild V. anguillarum in fish. In this study, a plasmid-free derivative MVAV6201, an effective live vaccine candidate, was used as a carrier strain to achieve the secretory delivery of recombinant proteins in V. anguillarum. The secretion mechanism was based on the Escherichia coli alpha-haemolysin (HlyA) transport system. The recombinant proteins were fused with the alpha-haemolysin secretion signal (HlyAs) and expressed from the commonly used HlyA secretion vector pMOhly1. Two HlyAs-tagged recombinant proteins, GFP-HlyAs and AngE-HlyAs, were constructed and their secretion characters in V. anguillarum investigated. In the case of GFP-HlyAs, nearly 70% of the total fusion protein was efficiently secreted into culture supernatant, and in the case of AngE-HlyAs, the secretion efficiency was determined to be about 300 microg L(-1) by Western blotting.

Animals↗

PubMed2004

A distance of 133-137 parsecs to the Pleiades star cluster.

Nearby 'open' clusters of stars (those that are not gravitationally bound) have played a crucial role in the development of stellar astronomy because, as a consequence of the stars having a common age, they provide excellent natural laboratories to test theoretical stellar models. Clusters also play a fundamental part in determining distance scales. The satellite Hipparcos surprisingly found that an extensively studied open cluster--the Pleiades (also known as the Seven Sisters)--had a distance of D = 118 +/- 4 pc (refs 2, 3), about ten per cent smaller than the accepted value. The discrepancy generated a spirited debate because the implication was that either current stellar models were incorrect by a surprising amount or Hipparcos was giving incorrect distances. Here we report the orbital parameters of the bright double star Atlas in the Pleiades, using long-baseline optical/infrared interferometry. From the data we derive a firm lower bound of D > 127 pc, with the most likely range being 133 < D < 137 pc. Our result reaffirms the fidelity of current stellar models.

Journal Article↗

PubMed2004

Spontaneous synaptic activity in chick vestibular nucleus neurons during the perinatal period.

The principal cells of the chick tangential nucleus are second-order vestibular neurons involved in the vestibuloocular and vestibulocollic reflexes. The spontaneous synaptic activity of morphologically identified principal cells was characterized in brain slices from 1-day-old hatchlings (H1) using whole-cell voltage-clamp recordings and Cs-gluconate pipet solution. The frequency was 1.45 Hz for spontaneous excitatory postsynaptic currents (sEPSCs) and 1.47 Hz for spontaneous inhibitory postsynaptic currents (sIPSCs). Using specific neurotransmitter receptor antagonists, all of the sEPSCs were identified as AMPA receptor-mediated events, whereas 56% of the sIPSCs were glycine and 44% were GABA(A) receptor-mediated events. On exposure to TTX, the frequency of EPSCs decreased by 68%, while the frequency of IPSCs decreased by 33%, indicating greater EPSC dependency on presynaptic action potentials. These data on spontaneous synaptic activity at H1 were compared with those obtained in previous studies of 16-day old embryos (E16). After birth, the spontaneous synaptic activity exhibited increased EPSC frequency, increased ratio for excitatory to inhibitory events, increased percentage of TTX-dependent EPSCs, and faster kinetics. In addition, the ratio for glycine/GABA receptor-mediated events increased significantly. Altogether, these data indicate that at hatching spontaneous synaptic activity of vestibular nucleus neurons in brain slices of the chick tangential nucleus undergoes appreciable changes, with increased frequency of EPSCs and glycinergic activity playing more important roles compared with the late-term chick embryo when GABAergic activity prevailed. The definition of this developmental pattern of synaptic activity in vestibular nucleus neurons should contribute to understanding how vestibular reflex activity is established in the hatchling chick.

Afferent Pathways↗

PubMed2003

A recombinant fusion protein and DNA vaccines against foot-and-mouth disease virus type Asia 1 infection in guinea pigs.

On the basis of amino acid (aa) sequence of the tandem repeat 133-158-20-34-133-158 which consisted of aa 133-158 of VP1 and aa 20-34 of VP4 of Foot-and-mouth disease virus (FMDV) type Asia 1 a recombinant prokaryotic expression vector pAS1-P encoding a fusion protein and eukaryotic expression vectors pAS1-E and pAS1-EdeltaCpG-ODN representing DNA vaccines were constructed. Guinea pigs immunized with these vaccines showed both neutralizing antibody and T cell proliferation responses. FMDV challenge tests for the first time showed that the recombinant fusion protein and pAS1-E and pAS1-EdeltaCpG-ODN vaccines protected 86%, 60% and 43% of guinea pigs from FMDV type Asia1 challenge, respectively. The results also indicated that the immune response of animals treated with the vector pAS1-E containing an oligodeoxynucleotide (ODN), which consisted of immunostimulatory cytosine-phosphate-guanosine (CpG) motifs, was augmented by CpG ODN.

Animals↗

PubMed2001

[Polymorphism of MAO-B gene and NAD(P)H: quinone oxidoreductase gene in Parkinson's disease].

OBJECTIVE: To investigate whether Parkinson's disease(PD) is associated with genetic polymorphism of intron 13 of monoamine oxidase B(MAO-B) and NAD(P)H: quinone oxidoreductase(NQO1) gene cDNA 609C to T. METHODS: Association study was performed in 126 PD patients and 136 healthy control subjects matched for age, sex and origin. The NQO1 gene polymorphism was analyzed with the polymerase chain reaction-restriction fragment length polymorphism, the polymorphism of intron 13 of MAO-B was analyzed by allele- specific PCR. RESULTS: The allelic frequency of the mutant T allele of NQO1 gene was significantly higher in the PD patients as compared to the controls(P<0.05). The relative risk of suffering from PD increased (OR=3.8) in the individuals with T allelic genotype of NQO1 gene, and the odds ratio was as high as 5.7 when the individuals with A or AA genotype of MAO-B gene coexisted with the T allele genotype of NQO1 gene. CONCLUSION: The cDNA 609T allele of NQO1 gene might be a risk factor of PD, which could be associated with the genetic susceptibility of PD. The high activity A or AA genotype of MAO-B and the low activity genotype of NQO1 gene might have synergistic effect. When both genotypes coexist, the risk of suffering PD will be increased greatly.

Aged↗

PubMed2001

[Genetic polymorphisms of cytochrome P450 1A1 and susceptibility of early-onset Parkinson's disease].

OBJECTIVE: To assess the possible association between the Msp I polymorphisms of cytochrome P450 1A1(CYP1A1) and the susceptibility of early-onset Parkinson's disease among Hans in the northern part of China. METHODS: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to analyze three genotypes A, B and C in 3'flanking region of CYP1A1 in 126 patients with idiopathic early-onset Parkinson's disease and 172 healthy controls. RESULTS: The frequencies of genotypes A, B and C in patients were 41.3%, 43.6% and 15.1% while those in the controls were 34.9%, 51.7% and 13.4%, respectively. No statistically significant difference in the frequencies of the three genotypes was observed between the two groups. The frequencies of two alleles were of no significant difference between the patients and controls. CONCLUSION: The above results suggest that the Msp I polymorphisms of cytochrome P450 1A1 itself might not be associated with idiopathic early-onset Parkinson's disease.

Adult↗

PubMed2001

Influence of fuel quality on vehicular NOx emissions.

The quality of gasoline and diesel fuel affects pollutant emissions from vehicles. By applying the COMPLEX model, developed by the US EPA and industry to relate fuel composition to vehicle emissions, this paper estimates the influence of improvements in gasoline quality to lower vehicular NOx emissions. A case study is performed for Guangzhou City that has NOx concentrations significantly above the national ambient air quality standards(NAAQS). The paper discusses the potential for reducing NOx in Guangzhou by improving the quality of gasoline.

Air Pollutants↗

PubMed2001

[Enrichment of organic matter and nitrogen in eroded bedloads].

Under natural rainfall, the influences of rainfall, slope gradient, tillage and fertilization on the enrichment ratio(ER) of organic matter(OM) and total nitrogen(TN) in eroded bedloads and the relationship between the ER and the composition of eroded bedloads was analyzed. The results showed that the enrichment of clay(ERclay) resulted in the enrichment of OM and TN, and the average value of ERclay, EROM and ERTN under different slope gradients was 1.77, 2.09 and 1.61, respectively. The soil erosion module was negatively correlated with EROM and ERTN. The measures for soil erosion may increase the EROM and ERTN affected by rainfall, slope gradient, tillage and fertilization.

Fertilizers↗

PubMed2001

[Association between dopamine transporter gene polymorphism and Parkinson's disease].

OBJECTIVE: To detect the association between dopamine transporter gene polymorphism and Parkinson's disease (PD). METHODS: The authors analyzed the difference in the distribution of the variable number tandem repeat (VNTR ) polymorphism within the 3' untranslated region of the DAT gene between 85 normal controls and 128 PD patients that were further divided into the senile subgroup (aged >50 years at onset of PD ) and the early-onset subgroup (aged </=50 years). RESULTS: There were significant differences in genotypic and allelic distribution between the control group and the PD group. The senile PD was strongly associated with the 7-copy allele and weakly with the 10-copy allele, and the early onset PD was mainly associated with the 9-copy allele. CONCLUSION: The findings not only support an association between DAT gene and PD but also suggest the relationship of the 3'VNTR polymorphism of DAT gene with the age at the onset of PD.

Adolescent↗

PubMed2001

Regional glucose metabolic increases in left auditory cortex in tinnitus patients: a preliminary study with positron emission tomography.

OBJECTIVE: To investigate the relationship between tinnitus and glucose metabolism in auditory cortex and whether positron emission tomography (PET) can be an objective tool in measuring tinnitus. METHODS: Eleven right-handed patients with severe tinnitus and ten right-handed control subjects participated in the 18F-FDG/PET study. Analysis with regions of interests was used to calculate asymmetry indices according to the formula: [(L-R) x 100/[(L + R) divided by 2]]. RESULTS: Glucose metabolism in the auditory cortex of tinnitus patients was asymmetric between the left and right auditory cortices, with that of the left being much higher than that of the right. The asymmetry indices of tinnitus patients was significantly higher than that of the control group (unpaired t test, P < 0.001). This revealed that the increased metabolic activity was present in the predominant left hemisphere with a significant focus on the superior and transverse temporal gyri (Brodmann areas 41 and 42, respectively corresponding to primary and secondary auditory cortex), and the results were independent of the subjective localization of the tinnitus sensation. CONCLUSION: It is suggested that the increased metabolism in the left auditory cortex is related to the tinnitus sensation. PET is capable of providing objective evidence for tinnitus and may be used as a potential tool in measuring tinnitus.

Adolescent↗

PubMed2001

[Effects of seed coating formulation on seedling characters of Atractylodes macrocephala].

The effects of seed coating formulation (SCF) of Atractylodes macrocephala Koidz. on seedling in two experimental plots located in Hangzhou and Jiande were studied, and desinged with L9(3(4)) orthogonal comparison. The results showed that the SCF with paclobutrazol (pp333) had a significant effect on the rate of germination at Hangzhou plot, all factors had no significant effects on length of seedlings in both plots, and both atonik (sodium O-nitrophenolate) and PP333 on the fresh or dry seedling weight had significant effects.

Asteraceae↗

PubMed2001

[High concentration ethanol continuous fermentation using yeast flocs].

Continuous ethanol fermentation using yeast flocs was carried out in 4 air-lift suspended-bed bioreactors operated in series. Drafted by CO2, with complete recycle of ethanol distilled effluent broth and at the dilution rate of 0.2/h, the average ethanol concentration of the fermentation broth was 96.6 g/L, while the average concentration of residual total sugar was 4.1 g/L and residual reducing sugar was 1.2 g/L.

Bioreactors↗

PubMed2001

[Induced tolerance to cardiac allografts with intrathymic injection of donor spleen cells].

OBJECTIVE: To study the methods and mechanisms of immune tolerance in cardiac transplantation. METHODS: Male DA rat hearts were transplanted to male Lewis rats using Ono's model and randomly divided into four groups: untreated (group I), intrathymic injection of 2.5 x 10(7) DA splenocytes to Lewis rat (group II), intraperitoneal injection of 1 ml rabbit anti-rat lymphocyte serum (ALS) to Lewis recipient (group III), intrathymic injection of 2.5 x 10(7) DA splenocytes combined with intraperitoneal injection of 1 ml rabbit anti-rat lymphocyte serum (ALS) to Lewis recipient (group IV). 21 days later heart transplantation was performed. Mean survival time (MST), histological changes and mixed lymphocyte reaction (MLR) were measured after operation. RESULTS: In the group of intrathymic injection of spleen cells combined with ALS treatment, the survival time of heart allografts [MST: (81.8 +/- 7.6)d] was significantly longer than in the groups I [MST: (7.3 +/- 1.0) d], group II [MST:(7.8+/- 1.0)d], and group III [MST(8.2 +/- 1.2) d, P < 0.01]. Only a few inflammatory cells infiltrated in cardiac allografts in group IV. MLR of group IV were significantly decreased compared with those of the normal control (P < 0.01). CONCLUSIONS: The role of thymus as a special site for induction and maintenance of specific immunological unresponsiveness to organ allografts was confirmed. T cell clonal deletion may play an important role in this immune tolerance.

Animals↗

PubMed2000

Mouse keratinocytes immortalized with large T antigen acquire alpha3beta1 integrin-dependent secretion of MMP-9/gelatinase B.

Remodeling of the extracellular matrix during tissue development, wound repair and tumor cell invasion depends on the coordinated regulation of cell adhesion receptors, matrix proteins and enzymes that proteolyse the extracellular matrix. Integrin alpha3beta1 is a major receptor on epidermal keratinocytes for laminin-5 in the cutaneous basement membrane and is required for normal basement membrane organization during skin development. alpha3beta1 is also expressed at high levels in the majority of adherent transformed cells and in most tumors, and it could have similar roles in extracellular matrix remodeling during tumorigenesis and cell invasion. In the present study, we show that alpha3beta1 expression is required in immortalized mouse keratinocytes (MK) for the production of the matrix metalloproteinase MMP-9/gelatinase B, an MMP that is coexpressed with alpha3beta1 in epithelial cell carcinomas and during wound healing, and contributes to the invasive potential of some tumor cells. MMP-9 was expressed in MK cells derived from wild-type mice, but not in MK cells derived from alpha3-null mice. Reconstitution of alpha3beta1 expression in alpha3-null MK cells through transfection with the alpha3 subunit restored MMP-9 secretion, indicating an alpha3beta1-dependent pathway for MMP-9 production. alpha3beta1-dependent expression of MMP-9 was associated with the immortalized phenotype, since nonimmortalized, primary keratinocytes required soluble growth factors, but not alpha3beta1, for efficient expression of MMP-9. Our results suggest that an alpha3beta1-independent pathway(s) for MMP-9 production is suppressed in keratinocytes immortalized with large T antigen, and that an alpha3beta1-dependent pathway is required for sustained production of MMP-9 in the absence of other pathways.

Actins↗

PubMed2000

Preliminary studies on parkin gene deletion at exons 1 to 6 in Chinese patients with praecox Parkinson's disease.

OBJECTIVE: To search parkin gene deletion mutations at exons 1 to 6 in Chinese patients with praecox Parkinson's disease (PPD) and analyze them together with the clinical features of PPD. METHODS: DNA was extracted from peripheral blood of PPD patients; deletion mutations of parkin gene were identified by PCR amplification and agarose gel electrophoresis. The clinical data were analyzed together with the above information. RESULTS: Out of 21 patients, 2 had exon 1 deletion, 2 exon 4 deletion, and 1 exon 6 deletion. The mean age of the patients with deletion mutation was 45.7+/-1.8 years. All of the patients who had parkin gene deletion mutation had tremor, rigidity and bradykinesia, but athetosis and family history of PD were not found. In additon, the deletion mutations of parkin gene at exons 2, 3, 5, were not found. CONCLUSION: There are deletion mutations of parkin gene at exons 1,4,6 in PPD of Chinese, and such deletions generally happen on middle-aged patients.

Adolescent↗

PubMed2000

[Soil nitrogen and organic matter losses under water erosion].

The results of artificial water-scoured experiment show that with the increase of water-scoured intensity, the losses of nitrate and ammonium in runoff, and those of organic matter and total N in sediment increased greatly, while the enrichment ratios of organic matter and total N in sediment reduced correspondingly. When the soils in gully-hilly loess region were fertilized with same amount of NH4NO3, the ammonium and nitrate loss in runoff was respectively 0.9-3.5% and 8.2-19.7% of the application amount. Nitrate mainly lossed in runoff, not in sediment. The correlation coefficient of soil erosion module, organic matter and total N loss with > 20 microns soil aggregates was -0.8935, -0.7928 and -0.8151, respectively. The content of > 20 microns soil aggregates could be used as an index to differentiate the soil organic matter and total N loss.

Fertilizers↗