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Biomedical subjects

D Yu

Publications and source records attributed to D Yu.

At least 127 records · Page 7Linked to original sources
PubMed1999

Expression of tobacco class II catalase gene activates the endogenous homologous gene and is associated with disease resistance in transgenic potato plants.

We have previously shown that healthy potato plants respond poorly to salicylic acid (SA) for activating disease resistance against the late blight fungal pathogen Phytophthora infestans. However, SA is essential for the establishment of potato systemic acquired resistance (SAR) against P. infestans after treatment with the fungal elicitor arachidonic acid (AA). To understand the molecular mechanisms through which AA induces SA-dependent SAR in potato, we have recently studied the expression of potato class II catalase (Cat2St) in comparison with its tobacco homologue, Cat2Nt, which has previously been shown to bind SA. In the present study, we show that tobacco Cat2Nt is expressed at high levels and accounts for almost half of total SA-binding activity detected in tobacco leaves. In contrast, potato Cat2St is not expressed in healthy leaves, which is associated with the low SA responsiveness of potato plants for activation of disease resistance mechanisms. Upon treatment with AA, expression of potato Cat2St is induced not only in AA-treated leaves, but also in the upper untreated parts of the plants, concomitant with the establishment of SA-dependent SAR to P. infestans. Moreover, expression of the tobacco Cat2Nt gene in transgenic potato plants leads to constitutive expression of the endogenous potato Cat2St gene and is associated with enhanced resistance to P. infestans. These results collectively indicate that plant SA-binding class II catalases may play an important role in the development of disease resistance, possibly by serving as biological targets of SA.

Catalase↗
PubMed1999

Decomplementation with cobra venom factor prolongs survival of xenografted islets in a rat to mouse model.

Although the involvement of complement in hyperacute rejection of xenotransplants is well recognized, its role in rejection of devascularized xenografts, such as pancreatic islets, is not completely understood. In this study, we investigated whether complement participates in the immunopathology of xeno-islet transplantation in a concordant rat to mouse model. Rat pancreatic islets were implanted under the kidney capsule of normal and cobra venom factor (CVF)-decomplementized diabetic C57BL/6 mice. Graft survival was monitored by blood glucose levels. Deposition of IgM and C3 on grafted islets in vivo or on isolated islets in vitro (after incubation with normal and decomplementized mouse serum), as well as CD4- and CD8-positive leucocyte infiltration of grafts, was checked by immunohistochemistry. In addition, complement-mediated cytotoxicity on rat islet cells was evaluated by a 3-(4, 5-dimethythiazolyl)-2.5-diphenyl-2H-tetrazolium-bromide (MTT) assay. A significant C3 deposition was found on grafted islets from the first day after transplantation in vivo, as well as on isolated islets after incubation with mouse serum in vitro. By MTT assay, complement-mediated cytotoxicity for islet cells was found. Decomplementation by CVF decreased C3 deposition on either isolated or grafted islets, delayed CD4- and CD8-positive leucocyte infiltration, led to significant inhibition of complement-mediated cytotoxicity for islet cells, and prolonged graft survival (mean survival time 21.3 versus 8.5 days; P<0.01). Our results indicate that decomplementation can prolong the survival time of devascularized xenografts across concordant species. The deposition of complement on transplanted islets may contribute to xenograft rejection by direct cytotoxicity and by promoting leucocyte infiltration.

Animals↗
PubMed1999

Identification of Bacillus anthracis strains in China.

As part of a project to establish a reference strain collection, phenotypic, biochemical and genetic analyses were carried out on 84 strains of Bacillus anthracis, 81 of them of Chinese origin from various sources. Particular differences from reports on isolates of other origins were the possession of fimbriae and single polar flagella with consequent motility in 77, self-agglutination by 64 and failure to ferment maltose in 60 of the Chinese strains. The findings were considered to be of significance to identification, classification and evolution of B. anthracis.

Animals↗
PubMed1999

Organ identity genes and modified patterns of flower development in Gerbera hybrida (Asteraceae)

We have used Gerbera hybrida (the cultivated ornamental, gerera) to investigate the molecular basis of flower development in Asteraceae, a family of flowering plants that have heteromorphic flowers and specialized floral organs. Flowers of the same genotype may differ in a number of parameters, including sex expression, symmetry, sympetaly and pigmentation. In order to study the role of organ identity determination in these phenomena we isolated and functionally analysed six MADS box genes from gerbera; these were shown by phylogenetic analysis to be orthologous to well characterized regulatory genes described from Arabidopsis and Antirrhinum. Expression analysis suggests that the two gerbera agamous orthologues, the globosa orthologue and one of the deficiens orthologues may have functional equivalency to their counterparts, participating in the C and B functions, respectively. However, the function of a second deficiens orthologue appears unrelated to the B function, and that of a squamosa orthologue seems distinct from squamosa as well as from the A function. The induction patterns of gerbera MADS box genes conform spatiotemporally to the multi-flowered, head-like inflorescence typical of Asteraceae. Furthermore, gerbera plants transgenic for the newly isolated MADS box genes shed light onto the mechanistic basis for some floral characteristics that are typical for Asteraceae. We can conclude, therefore, that the pappus bristles are sepals highly modified for seed dispersal, and that organ abortion in the female marginal flowers is dependent upon organ identity and not organ position when position is homeotically altered.

Asteraceae↗
PubMed1999

Identification of two novel deletion mutations within the Gs alpha gene (GNAS1) in Albright hereditary osteodystrophy.

Albright hereditary osteodystrophy (AHO) is a genetic disorder characterized by short stature, skeletal defects, and obesity. Within AHO kindreds, some affected family members have only the somatic features of AHO [pseudopseudohypoparathyroidism (PPHP)], whereas others have these features in association with resistance to multiple hormones that stimulate adenylyl cyclase within their target tissues [pseudohypoparathyroidism type Ia (PHP Ia)]. Affected members of most AHO kindreds (both those with PPHP and those with PHP Ia) have a partial deficiency of Gs alpha, the alpha-subunit of the G protein that couples receptors to adenylyl cyclase stimulation, and in a number of cases heterozygous loss of function mutations within the Gs alpha gene (GNAS1) have been identified. Using PCR with the attachment of a high melting domain (GC-clamp) and temperature gradient gel electrophoresis, two novel heterozygous frameshift mutations within GNAS1 were found in two AHO kindreds. In one kindred all affected members (both PHP Ia and PPHP) had a heterozygous 2-bp deletion in exon 8, whereas in the second kindred a heterozygous 2-bp deletion in exon 4 was identified in all affected members examined. In both cases the frameshift encoded a premature termination codon several codons downstream of the deletion. In the latter kindred affected members were previously shown to have decreased levels of GNAS1 messenger ribonucleic acid expression. These results further underscore the genetic heterogeneity of AHO and provides further evidence that PHP Ia and PPHP are two clinical presentations of a common genetic defect. Serial measurements of thyroid function in members of kindred 1 indicate that TSH resistance progresses with age and becomes more evident after the first year of life.

Amino Acid Sequence↗
PubMed1999

Expression of alpha-1 proteinase inhibitor in human islet microvascular endothelial cells.

There is a microcirculation system within the islets of Langerhans. However, little is known about the phenotypic and functional characterization of islet microvascular endothelial cells (MVEC). In this study, we purified MVEC from human pancreatic islets by using Ulex europaeus (Sigma, St. Louis, MO) agglutinin-1 (UEA-1)-coated dynabeads (Dynal A.S., Oslo, Norway). These purified human islet MVEC (HI-MVEC) express von Willebrand factor, take up high levels of acetylated LDL, and upregulate endothelial cell leukocyte adhesion molecule 1 in response to tumor necrosis factor-alpha. Ultrastructure examination shows the presence of microvilli and fenestrations on the cell surface, Weibel-Palade bodies in the cytoplasm, and tight junctions between cells. Furthermore, we show that vascular endothelial cell growth factor contributes to the formation of surface fenestrations on cultured HI-MVEC. After purification, HI-MVEC exhibit a very low proliferation capacity and are strongly resistant to trypsin, compared with other original MVEC. We also demonstrate that alpha-1 proteinase inhibitor (Api) is expressed on HI-MVEC and specifically located at the area of cell-cell junctions. By reverse transcription-polymerase chain reaction, a significant messenger RNA band of Api was found only in HI-MVEC, but not in other organ-derived MVEC, indicating that expression of Api is islet MVEC specific. Antibodies to Api significantly reversed the resistance to trypsin and promoted proliferation of HI-MVEC, suggesting that these specific functional characteristics of HI-MVEC are related to the expression of Api. These results indicate that HI-MVEC exhibit some specific morphological and functional characteristics that differ from MVEC derived from other organs.

Antibody Specificity↗
PubMed1999

Effect of selective screening for gestational diabetes.

OBJECTIVE: To estimate the percentage of pregnant women who would not be screened and the percentage of women with gestational diabetes mellitus (GDM) who would possibly remain undiagnosed if the American Diabetes Association's (ADA's) new selective screening recommendations are used rather than universal screening for GDM. RESEARCH DESIGN AND METHODS: Since 1987, the University of Michigan Health System has performed universal screening for GDM. In 1997, the ADA recommended that women having all four of the following characteristics need not be screened: age < 25 years, not members of an ethnic/racial group with a high prevalence of diabetes, normal body weight, and no family history of diabetes. We studied a random sample of the 25,118 deliveries at the University of Michigan between 1987 and 1997 to determine the prevalence of these four characteristics in our obstetric population. We also studied the prevalence of these four characteristics in 200 women who were diagnosed with GDM in the Endocrine Testing Unit and delivered at the University of Michigan between 1987 and 1997. RESULTS: Approximately 10-11% of women who delivered possessed all four low-risk characteristics and would not have been screened for GDM according to the new ADA recommendations. Only 4% of women (5 of 141) with GDM who delivered and for whom data on all four characteristics were reported possessed all four low-risk characteristics and would not have been screened. CONCLUSIONS: If the new ADA selective screening recommendations are used, few women with GDM will be missed (4%) but approximately 90% of pregnant women will still need to be screened for GDM.

Adult↗
PubMed1999

Effects of coenzyme Q10 on myocardial protection during cardiac valve replacement and scavenging free radical activity in vitro.

BACKGROUND: To evaluate the effects of CoQ10 on myocardial protection in patients undergoing cardiac valve replacement and direct scavenging free radicals activity in vitro. METHODS: Twenty-four patients were randomly divided into two groups. Twelve patients in the CoQ10 group received intravenous and intracoronary CoQ10-treated "round the operative period". Twelve patients in the control group received no CoQ10-treatment. MEASURES: Plasma malondialdehyde (MDA) concentration, erythrocyte superoxide dismutase (SOD) activity, and serum cardiac isoenzyme of creatine kinase (CK-MB) were measured in the perioperative and postoperative period. The effects of CoQ10 direct scavenging free radicals were determined with electron spin resonance (ESR) and spin-trapping techniques by an in vitro study. RESULTS: Plasma MDA concentration and serum CK-MB levels in the CoQ10 group were significantly lower than those in the control group. Erythrocyte SOD activity in the CoQ10 group was significantly higher than that in the control group. CoQ10 showed an obvious hydroxyl radical scavenging activity, but it could not scavenge superoxide anion radicals. CONCLUSIONS: These findings demonstrated that the use of intravenous and intracoronary CoQ10-treatment may play a more beneficial protective role during cardiac valve replacement through its antioxidant properties and membrane stabilization, as well as through its ability to scavenge hydroxyl radicals directly.

Adult↗
PubMed1999

Inhibition of the transcription factor nuclear factor-kappa B by adenoviral-mediated expression of I kappa B alpha M results in tumor cell death.

BACKGROUND: The activation of transcription factor nuclear factor-kappa B (NF-kappa B) by extracellular stimuli has been shown to protect cells from apoptotic cell death. Inhibition of NF-kappa B activity should result in increased tumor cell killing in response to apoptotic stimuli. This study evaluated the effect of inhibition of NF-kappa B on a series of sarcoma and normal cell lines. METHODS: Human sarcoma cell lines (HT1080, SKLMS-1, and MFH) and normal cell lines (NLF and BSMC) were infected with an adenoviral dominant-negative mutant Ad5I kappa B alpha M in vitro. Control cells were infected with the empty adenoviral vector and mock-infected with media alone. Viable cell counts were determined by microscopic evaluation on days 1 to 6 after infection. Cell proliferation was determined at 48 hours by MTT (1-[4,5-dimethylthiazol-2-yl]-3,5-dephenylformazan) assay. RESULTS: All cell lines showed evidence of successful adenoviral infection as evidenced by the infection of all cell lines with the adenoviral marker gene Ad5 LacZ. All the tumor cells were found to have a significant decrease in cell viability and proliferation after treatment with the Ad5I kappa B alpha M gene compared with both mock-infected cells and cells infected with empty vector (P < .0001). The normal cell lines, although able to be successfully infected, did not show a significant decrease in cell viability or proliferation with adenoviral-mediated I kappa B alpha M infection. CONCLUSIONS: Inhibition of NF-kappa B through adenoviral-mediated infection of the dominant-negative inhibitor I kappa B alpha M resulted in a significant decrease in tumor cell viability and proliferation while having no deleterious effect on normal cell lines. The Ad5I kappa B alpha M gene therefore could be potentially used as a clinical treatment for patients with soft-tissue sarcoma.

Adenoviridae↗
PubMed1999

Studies on biosensor to determine diacetyl.

We studied the purification of diacetyl reductase, the preparation of a biosensor, and its performance. With diacetyl reductase and reduced coenzyme I (NADH) co-immobilized as working membrane, NAD+/NADH produced in the course of diacetyl reduction was connected with Fe2+/Fe to build a biosensor. The biosensor could be used to determine diacetyl concentration within the range from 0.1 microgram/mL to 0.5 microgram/mL and the response time was less than two minutes, and its performance was stable within 9 days. The experiments showed that typical metal ions and organics in nominal concentration did not affect the performance of the biosensor, meanwhile, the interference of dissolved oxygen on the performance of biosensor and regeneration of coenzyme I (NADH) were solved to some extent.

Acetoin Dehydrogenase↗
PubMed1999

[Effects of metallothionein (MT) on burned skin of rats].

OBJECTIVE: To elucidate the relationship between skin viability and lipid peroxidation after deep partial thickness burn injury. METHODS: Deep partial thickness burn was produced. Metallothionin (MT) in different concentrations (0.5 x 10(-6) mol/L, 1 x 10(-5) mol/L) was topically applied. Oxygen consumption, succinate dehydrogenase(SDH), Schiff's base contents and healing time of wound were determined in 24 Wistar rats. Specimens were harvested at 8, 24, and 48-hour postburn. RESULTS: Oxygen consumption and SDH value decreased and Schiff's base value increased after burn injury. With the application of MT, oxygen consumption and SDH value of burned skin were significantly higher compared with control group, and Schiff's base value was significantly lower (P < 0.05 or P < 0.01). The mean healing time of burned wound was two days less in two MT protection groups. CONCLUSION: MT may be beneficial in improving postburn skin viability by attenuating lipid peroxidation of burned tissue.

Animals↗
PubMed1999

Experimental observation of effects of triclabendazole on Paragonimus westermani infection in dogs.

OBJECTIVE: To observe the therapeutic effects of triclabendazole in the treatment of dogs with Paragonimiasis westermani. METHODS: Six dogs were experimentally infected, each with 100 metacercariae of Paragonimus westermani intraperitoneally and divided into untreated and treated groups, 3 dogs were treated orally with triclabendazole 100 mg/kg.d-1 for 2 consecutive days on day 170 after infection. Stool egg count was done by Stoll method. All dogs were killed on day 38 after treatment and the number of worm cysts and worms in the lungs were examined by naked eye and microscopically. RESULTS: Stool eggs became negative from day 7 to day 14 after starting chemotherapy in treated dogs. The numbers of worm cysts in the lungs of untreated dogs were 18, 24 and 24 on necropsy, while those in the treated dogs were 10, 7 and 4, respectively. The numbers of adult worms in the untreated dogs were 38, 51 and 42, while in the treated dogs only 2 small adult worms were found in one dog and no worm was found in the other two dogs. The mean worm reduction rate was 98.5%. CONCLUSION: Triclabendazole is highly effective against Paragonimus westermani in experimentally infected dogs.

Animals↗
PubMed1999

[Measuring of spontaneous otoacoustic emissions of adolescence and its significance].

OBJECTIVE: In order to study the relationship between spontaneous otoacoustic emissions (SOAE) and cochlear function. METHOD: SOAE of 50 normal hearing young people were measured. The incidences, amplitudes and frequencies of SOAE were obtained. RESULT: The SOAE incidence was 40% in 100 ears of 50 cases and there was no significant difference in sexuality and laterality (P > 0.05); In the 40 cases who had SOAE, the amplitudes ranged from--27.5 dB SPL to 9.7 dB SPL and the frequencies ranged from 269 Hz to 5,660 Hz, without sexual difference; There is no significant difference between SOAE and threshold of pure tone acoustic (P > 0.05). CONCLUSION: The appearance of SOAE indicated good cochlear function.

Adult↗
PubMed1999

[Experimental therapy of Pagumogonimus skrjabini infection in rats with triclabendazole].

AIM: To observe the therapeutic effect of triclabendazole in rats infected with Pagumogonimus skrjabini. METHODS: Metacercariae of P. skrjabini were isolated from crabs (Sinopotamon) collected from two endemic areas (Weiyuan County of Sichuan Province and Wansheng District of Chongqing Municipality). Wistar rats were each infected intraperitoneally with metacercariae. One month and two months after infection, the infected rats were treated with triclabendazole at the total dosage of 300 mg/kg over 2 days, 450 mg/kg over 3 days and 600 mg/kg over 3 days, respectively. RESULTS: The worm reduction rates were 50%, 80% and 87% respectively one month after completion of tretment. Dead worms (about 1 mm size) recovered from the muscles, liver, abdominal cavity, chest cavity and lungs were signicantly diminished in size and weight in comparison with those of the control group. Many large (about 1 cm) black-colored distended worm cysts usually with two adult worms and many eggs were found in the lungs of the control rats. Most worm cysts in the treated groups of rats were found to be atrophied, changing into hemorrhagic-necrotic patches. CONCLUSION: Triclabendazole is highly active against P. skrjabini in rats.

Animals↗
PubMed1999

[Study on the nasal resonance].

OBJECTIVE: In order to understand the resonant function of the nasal cavity (including nasal sinuses) which is one of the resonant organs of the human body. METHOD: The maximum frequency, mean frequency and the number of harmonics of five vowels [a], [e], [i], [o], [u] were compared before and after packing of the anterior nasal cavity. RESULT: The result was analyzed statistically and showed no significant difference. CONCLUSION: It proved that the front part of the nasal cavity plays no important role in the function of the nasal resonance.

Adolescent↗
PubMed1999

[The submucosal structure of the endolymphatic sac of guinea pigs].

OBJECTIVE: To investigating the submucosal structure of the endolymphatic sac (ES), so as to analyse the role of ES in the function of inner ear. METHOD: The temporal bone of the guinea pigs were cleared in methyl salicylate and inspected under a stereomicroscope. The ultrastructure of endolymphatic sac has been observed by transmission electron microscope. RESULT: The extensive vascular system around the sac and has compact contact with sinus sigmoid. Its submucosal space comprises both arterioles and venules, as well as lymphatic sinus. CONCLUSION: The result suggests that the ES is a very metabolically active structure and has a pressure regulating function. The disturbance of endolymphatic resorptive function seems to result endolymphatic hydrops after the vascular supply poverty of endolymphtic sac. It's may be the causative factor of Meniere's disease.

Animals↗