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Biomedical subjects

C Jiang

Publications and source records attributed to C Jiang.

At least 181 records · Page 10Linked to original sources
PubMed1996

A filter elution assay for the simultaneous detection of DNA double and single strand breaks.

This paper reports a gravity-flow filter elution assay that permits the simultaneous detection of DNA double strand breaks (DSBs, as neutral elutable DNA) and DNA single strand breaks (SSBs, as alkaline elutable DNA). This assay is based on a modification of a conventional gravity-flow alkaline elution procedure. The elution fraction resulting from cell lysis before the application of the alkaline elution buffer provides an estimate of DNA DSBs, while the fraction eluted by the alkaline buffer (pH 12.3) measures the extent of DNA SSBs. Data show that, in addition to its good detection sensitivity for SSBs, this method provides a sensitive measure of DNA DSBs. As an illustration of its specificity, this method unambiguously distinguished DNA SSBs induced by X-irradiation of mouse leukemia L1210 cells from DNA DSBs occurring in cells undergoing nucleosomal DNA fragmentation and apoptosis. The neutral elution fraction is a good predictor of loss of cell viability induced either by selenite at pharmacological levels or by growth factor depletion. The filter elution method reported is more specific and informative than a nick translation assay for the detection of DNA strand breaks.

Animals↗
PubMed1996

Nucleosome positioning properties of the albumin transcriptional enhancer.

Considering the importance of nucleosome position with regard to how regulatory factors recognize their binding sites in chromatin, we have investigated the inherent nucleosome positioning properties of a transcriptional enhancer of the albumin gene. In the liver, where the albumin gene is highly expressed, the enhancer exists in an array of precisely positioned, nucleosome-like particles with transcription factors bound. In the absence of specific binding factors, such as in non-liver tissues or in polynucleosome arrays assembled in vitro, nucleosomes are randomly positioned over the enhancer. Herein we investigate the intrinsic nucleosome positioning properties of the central enhancer sequence assembled into mononucleosome core particles in vitro. We find that the enhancer DNA prefers three translational positions, each of which utilizes different rotational settings on the nucleosome core. We conclude that DNA binding factors that position nucleosomes may do so by stabilizing one configuration out of several that can be adopted by the underlying DNA, and that the potential exists for different positions to be stabilized at different stages of development.

Albumins↗
PubMed1996

Requirement of a CCGAC cis-acting element for cold induction of the BN115 gene from winter Brassica napus.

Mutation of the core pentamer, CCGAC, of two putative low temperature responsive elements (LTREs) in the 5'-proximal region for the winter Brassica napus cold-induced gene BN115 was carried out. Analyses of transient expression of the resultant mutated BN115 promoter-GUS fusions revealed the loss of low-temperature regulation by the promoter. This indicates that the CCGAC sequence is critical to the low-temperature response in the BN115 gene. In contrast, mutation of two G-boxes, CACGTG, staggered between the LTREs in the same region of the promoter did not alter cold-inducible gene expression. Replacement of a possible enhancer region of the BN115 promoter with the enhancer from the CaMV 35S promoter resulted in a several-fold increase in low temperature-induced GUS activity.

Base Sequence↗
PubMed1996

Trauma care in China: challenge and development.

The People's Republic of China has significantly improved the general health of its people by a concerted effort in primary health care but trauma care and its prevention remains a problem. This paper provides an overview of the strengths and weaknesses of the trauma-care system in China and proposes a strategy for its future development. This includes public-health legislation, the integration of military and civilian practice to provide comprehensive care from the scene of the incident through to rehabilitation, medical audit, the introduction of postgraduate trauma-management training courses and international academic exchanges.

China↗
PubMed1996

Reduction of Saccharomyces cell adhesion by liquid mechanical vibration.

The effect of liquid mechanical vibration on the adhesion of Saccharomyces cerevisiae cells to the internal glass surface of a pipette was studied using a 25 Hz vibration source. The maximum vibration amplitude was 1.06 mm (peak to peak) along the pipette direction. Relative movements between the pipette and yeast suspension in it were produced by vibration and reduced the cell adhesion. The reduction in adhesion was affected by both vibration amplitude and suspension pH. Analysis showed that in routine cell counts, cell adhesion to the pipette wall was a significant error source. The construction of a vibration device for routine cell count work appears feasible.

Cell Adhesion↗
PubMed1996

Diversity of soil actinomycetes in yunnan, china.

Since 1978, about 4,200 soil samples have been collected from 22 selected areas of various vegetational and climatic types throughout the province of Yunnan. Actinomycetes of 29 genera were isolated by the methods employed. The correlations between diversity and climate were grouped into tropical, subtropical plateau, cool temperate mountain, and snowy mountain types. Actinomycete populations of the first two types were more complex than were the other ones. Correlations between actinomycete diversity and vegetation were also attempted. Six types of vegetation were compared. The diversity of actinomycetes was greatest in soil samples of a primeval forest, with an average of 9.0 genera isolated, followed by secondary forest and vegetable farmland samples, with averages of 6.7 and 6.5 genera isolated, respectively. The upper limit for the occurrence of thermophilic actinomycetes is about 3,500 m above sea level in Yunnan. Psychrophilic actinomycetes were isolated at up to the same altitude. In addition, the drier and poorer the soil was and the cooler the climate was, the lower the count of actinomycetes was and the higher the percentage of streptomycetes observed was. The genus Streptomyces appears to be the most important in ecological function. It represents up to 90% of all soil actinomycete diversity in Yunnan and is likely an important characteristic of the soil actinomycete population.

Journal Article↗
PubMed1996

Diversity of aquatic actinomycetes in lakes of the middle plateau, yunnan, china.

A total of 749 sediment and water samples were collected from 12 lakes of the Middle Plateau of Yunnan from 1983 to 1993. The diversity and biological characteristics of the aquatic actinomycetes in these lakes were studied. Sixteen genera of actinomycetes were isolated from these samples. Micromonospores assumed a notable dominance (from 39 to 89%) in the actinomycete populations of these lake sediments. Streptomycetes were the second most abundant organisms. The diversity and counts of actinomycetes varied with the season. Thermophilic actinomycetes have a wide distribution in these lakes, but their counts were smaller. The cell wall compositions of certain Micromonospora and Streptomyces strains from an alkaline lake revealed an unusual combination of glycine and isomers of diaminopimelic acid. It seems that aquatic actinomycetes play a significant role in the decomposition of organic substances, including some toxic compounds such as phenol, in these lakes. It also appears that aquatic actinomycetes are one of the important resources for screening useful enzymes and metabolites.

Journal Article↗
PubMed1996

Ability of adenovirus vectors containing different CFTR transcriptional cassettes to correct ion transport defects in CF cells.

Cystic fibrosis (CF) airway epithelial cells exhibit defective adenosine 3',5'-cyclic monophosphate (cAMP)-mediated chloride (Cl) secretion, abnormal hyperabsorption of sodium (Na+), and aberrant fluid transport. Adenovirus-mediated transduction of cystic fibrosis transmembrane conductance regulator (CFTR) corrects these ion and fluid transport abnormalities in CF cells. However, several challenges remain pertaining to the use of adenovirus vectors for gene delivery, including the efficiency of gene transfer and the host response to the vector. To improve the efficacy of adenovirus-mediated gene transfer, we have constructed a series of recombinant adenoviruses containing different CFTR transcriptional units, and we have evaluated their relative ability to correct electrolyte and fluid transport in polarized CF airway epithelial cells. The ability of the vectors to correct the CF Cl- transport defects was greatest when the human cytomegalovirus promoter was used. The E1a and phosphoglycerate kinase promoters resulted in the greatest persistence of functional CFTR expression. Efficacy of gene expression by recombinant adenoviruses improved as the cells were treated with increasing multiplicities of infection, as the duration of viral contact with the target cells was lengthened, and when the virus concentration was increased. Transduction of functional CFTR Cl- channel activity reversed the abnormal Na+ hyperabsorption observed in CF cells in a dose-dependent manner, suggesting that Na+ channel activity is downregulated by CFTR. Although efficient correction of both cAMP-mediated Cl- transport and fluid secretion could be achieved readily with these vectors, normalization of the Na+ absorption required vector administration at high multiplicities of infection.

Adenoviruses, Human↗
PubMed1996

QTL for insect resistance and drought tolerance in tropical maize: prospects for marker assisted selection.

Insects and drought cause severe losses in the production of maize in many developing countries. Conventional breeding efforts to enhance the level of resistance to a number of insect pests and tolerance to drought have been successful, although only through large efforts of many breeders and over a large period of time. Continued improvements will only be possible through substantial investment of resources. Recently, success in identifying quantitative trait loci (QTL) in several plant species using various molecular marker systems offers alternative methods for accelerating conventional breeding programs. As the first step towards using molecular markers in CIMMYT's maize breeding program, restriction fragment length polymorphisms (RFLPs) have been used to understand the genetic basis of resistance to two corn borer species, southwestern corn borer and sugarcane borer, and to one major component of drought tolerance, anthesis-silking interval. A number of QTL with effects large enough to be regarded as significant in breeding were detected for each of these traits and many of them presented stable effects over environments. While variability in the number and location of QTL has been found when compared across populations, several loci were found to be quite consistent. Simple calculations can be made which estimate that the total genetic potential in maize for these traits is high. It is argued that to ultimately access and manipulate this potential, the use of linked molecular markers as indirect selectable markers is both feasible and necessary.

Adaptation, Physiological↗
PubMed1996

[Normalization of acupuncture anesthesia used in operation of neoplasm in functional area or deep site of brain].

From October 1990 to December 1995, the national cooperative neurosurgical acupuncture research group had already accumulated 100 clinical cases, consisting of 20 cases in deep site of brain, 80 cases in the functional region. By the same manipulative procedures and scaling criteria, the indication, choice of acupoints, stimulus parameters and adjuvants were studied. Practically, the results was not only reliable, but repetitive highly, 98% the cases belonged to grade I (success). We suggest that acupuncture anesthesia should be used as one of the usual methods of anesthesia. In this paper, the relative specification of acupuncture, the mechanism of methods for operation were discussed. In the meantime, the advantages and the remaining problems of acupuncture anesthesia in craniocerebral operations were also mentioned.

Acupuncture Analgesia↗
PubMed1996

[Histopathological and immunohistochemical studies on medullary thyroid carcinoma].

In order to study the multidifferentiation of medullary carcinoma of the thyroid gland (MCT), 24 cases of MCT were examined for the presence of immunoreactive calcitonin (CT), thyroglobulin (Tg), chromogranin A (CgA), somatostatin (SS), serotonin (5-HT), S-100 protein (S-100), neuron-specific enolase (NSE), vasoactive intestinal polypeptide (VIP), adrenocorticotrophin (ACTH) and neurofilament protein (NF) by using immunohistochemical ABC methods. Results showed that CT-immunoreactive cells were present in all tumors. Tg was present in three tumors. 23 cases contained CgA-immunoreactive cells. 14 tumors contained 5-HT-immunoreactive cells, 10 cases were immunoreactive to NSE and SS. 4 tumors contained VIP-immunoreactive cells and only one cases was positive for S-100. The demonstration of immunoreactivity for multiple antigens in 24 cases suggests that the origin of medullary thyroid carcinoma may originate from neuroectoderm cells potentially capable of producing numerous hormone substances. In addition, as the neoplastic cells in 12% of the tumors containing hormone substances as well as thyroglobulin, it is suggested that follicular epithelial differentiation and mixed medullary thyroid carcinoma may be more common than previously suspected. Recent studies indicate that mixed carcinoma of the thyroid may be derived from common stem cells in posterior branchia capable of differentiating into both follicular and parafollicular tumor cells.

Adult↗
PubMed1996

[Prevention of peridural fibrosis and adhesion after laminectomy: an experimental study in rats].

An experimental study on the effectiveness of various materials including poly carboxymethylcellulose (PCMC), gelatin foam (GF), ligment (L), free fat (FF) in prevention of peridural fibrosis and adhension (PDA) was done in 144 SD rats using a total laminectomy model (L1-2). PDA was measured with a double-blind protocol at 2, 4, 8, 12 weeks postoperatively by gross anatomical appearance (blunt-dissection), microscopical evaluation, computed imaging analysis and MRI enhanced with gadolinium. The results demonstrated that the peak of PDA is within 8 weeks after operation. PCMC, as a three dimensional protective material, could effectively inhibit PDFA after laminectomy, but GF and L could not. SHA had some effect in the early stage, but not in the late period. For FF though it could effectively prevent PDA, the incision infection rate was higher, the atrophy and necrosis of FF were serious. What is more, almost all transplanted fat remained in situ extended into the spinal cord in some measure after 8 weeks postoperatively.

Animals↗
PubMed1996

[Interaction of cis-regulatory element in the 5' flanking sequence of human beta-globin gene with trans-acting factors at different developmental stages].

Human beta-globin gene mainly expressed in the adult bone marrow, while not expressed in fetal liver, adult liver and K562 cells. Using gel mobility shift assay, different protein factors binding to the regulatory elements (from -372 to -194 bp) in the 5' flanking sequence of human beta-globin gene were detected in the nuclear extracts from human fetal liver, adult liver and K562 cells respectively. Competitive experiments showed that both the protein factors from adult and K562 cells not only bind to negative control region 2 (NCR 2, from -372 to -224 bp), but also bind to positive control region (PCR, from -223 to -194 bp), suggesting that there may be similar mechanism to silence the expression of human beta-globin gene in these two kind of cells. The protein factor in human fetal liver only binds to NCR 2, indicating that there is a particular silencing mechanism for beta-globin gene expression in human fetal stage.

Fetus↗
PubMed1996

[Protective effect of active components extracted from radix Astragali on human erythrocyte membrane damages caused by reactive oxygen species].

A study has been made on the protective activities of active components extracted from Radix Astragali by using reactive oxygen species initiated lipid peroxidation of purified human erythrocyte membrane. The results show that the total flavonoids of Astragalus and total saponins of Astragalus can significantly inhibit the membrane lipid peroxidation generated by O2.-, H2O2 and UV rays, while the total polysaccharide of Astragalus possesses weaker protective activity.

Drugs, Chinese Herbal↗
PubMed1995

Dissociation of the genotoxic and growth inhibitory effects of selenium.

The effects of forms of selenium compounds that enter the cellular selenium metabolic pathway at different points were investigated in a mouse mammary carcinoma cell line. The goal of these experiments was to determine if the genotoxicity of selenium, defined as its ability to induce DNA single-strand breaks, could be dissociated from activities proposed to account for its cancer inhibitory activity. The results demonstrated that growth inhibition, measured as inhibition of cell proliferation and induction of cell death, was induced by all the forms of selenium evaluated. However, sodium selenite and sodium selenide, which are metabolized predominantly to hydrogen selenide, caused the rapid induction of DNA single-strand breaks as an early event that preceded growth inhibition. Interestingly methylselenocyanate and Se-methylselenocysteine, which are initially metabolized predominantly to methylselenol, induced growth inhibition in the absence of DNA single-strand breakage. Differences in the time course of selenium retention, in the occurrence of membrane damage, and in the induction of morphological changes by selenite versus methylselenocyanate were noted. Collectively, these data indicate that different pathways affecting cell proliferation and cell death are induced depending on whether selenium undergoes metabolism predominantly to hydrogen selenide or to methylselenol.

Animals↗
PubMed1995

Major differences in response to graded hypoxia between hypoglossal and neocortical neurons.

Intracellular electrophysiologic recordings were performed in brain slices from adult rats to compare the response of brain stem hypoglossal neurons (XII) and layer II/III neocortical neurons (NCX) to two levels of oxygen deprivation (hypoxia, pO2 = 15-20 Torr; anoxia, pO2 = 0 Torr). These recordings were also used during re-oxygenation after hypoxia or anoxia to study neuronal recovery. Both groups of neurons showed a greater response to anoxia than hypoxia in terms of membrane potential (Vm) and input resistance (Rm). When the two groups were compared at each level of O2, XII depolarized more and in a shorter period of time than NCX. During anoxia, XII neurons responded with anoxic depolarization (AD) of > 20 mV/min by 3 min, along with a large decrease in Rm. NCX neurons, on the other hand, exhibited AD after a mean latency of approximately 9 min and 18% of NCX neurons did not even show AD. Although all neurons (both XII and NCX) recovered when re-oxygenated before or at AD, XII neurons failed to recover from periods of anoxia that were well tolerated by NCX neurons. We conclude that: (1) there are marked differences in the magnitude and trajectory of membrane depolarization between XII and NCX neurons in response to O2 deprivation, with NCX neurons showing a much longer latency to AD during anoxia than XII; and (2), when exposed to periods of anoxia of similar duration and severity, XII neurons are less likely to recover than NCX neurons and XII neurons may, therefore, be inherently more vulnerable to anoxia-induced injury than NCX neurons.

Animals↗
PubMed1995

A mechanistic link between an inherited and an acquired cardiac arrhythmia: HERG encodes the IKr potassium channel.

Mutations in HERG cause an inherited cardiac arrhythmia, long QT syndrome (LQT). To define the function of HERG, we expressed the protein in Xenopus oocytes. The biophysical properties of expressed HERG are nearly identical to the rapidly activating delayed rectifier K+ current (IKr) in cardiac myocytes. HERG current is K+ selective, declines with depolarizations above 0 mV, is activated by extracellular K+, and is blocked by lanthanum. Interestingly, HERG current is not blocked by drugs that specifically block IKr in cardiac myocytes. These data indicate that HERG proteins form IKr channels, but that an additional subunit may be required for drug sensitivity. Since block of IKr is a known mechanism for drug-induced cardiac arrhythmias, the finding that HERG encodes IKr channels provides a mechanistic link between certain forms of inherited and acquired LQT.

Animals↗