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Biomedical subjects

D Cai

Publications and source records attributed to D Cai.

At least 37 records · Page 2Linked to original sources
PubMed2000

Age-related changes of aqueous protein profiles in rat fast and slow twitch skeletal muscles.

Two-dimensional electrophoresis was used to generate the aqueous protein expression patterns of rat extensor digitorum longus muscle (EDL, fast twitch muscle) and solues muscle (SOL, slow twitch muscle) of different ages. Two specific protein spots, S1 and S3, were identified from EDL muscles at the ages of 12 and 18 months onward respectively. In the EDL muscles of aged rat (24 months) after intensive exercise training, S3 was still detected while S1 disappeared. In addition, diaphragm muscle (DIA, fast twitch muscle), which retains physically active throughout the life span, was used as nondisuse control. The results showed that the expressions of S1 and S3 in 24-month DIA muscle were identical with the trained aged EDL muscle. It is suggested that exercise might delay the onset of S1 expression. However, the expression of S3 over age seemed to be progressive and exercise independent. Another protein spot, S2 was identified to express only in young EDL and SOL muscles, but its expression decreased over age. Furthermore, exercise has no effect on S2 expression since S2 could not be detected in aged DIA as well as trained aged EDL and SOL muscles. These results indicated that aqueous protein expression patterns of skeletal muscle undergo changes during aging. Some of these changes such as S2 and S3 appear progressively, and some such as S1 could be delayed by exercise. S3 was identified as ubiquitin, which might play an important role in protein degradation during skeletal muscle aging process.

Aging↗
PubMed2000

Photoelectrochemistry as a novel strategy for DNA hybridization detection.

The special properties of ssDNA and dsDNA molecules in structure and electric behavior, may offer us some new ideas for the fabrication of genosensors and DNA-chips. In this work, the photoelectrochemical method was firstly employed to characterize the photoelectric behavior of a ssDNA probe electrode, which was prepared with the self-assembly technique, and its resulting dsDNA electrode. The obvious decrease in the photocurrent of the dsDNA modified electrode at open potential or a bias voltage indicated that photoelectrochemistry was another useful method for DNA hybridization detection. Using the special design of ssDNA probes, we attempt to discuss further the relationship between the properties of DNA molecules and their photoelectric behaviors. In addition, the electrochemical impedance method was employed to verify the occurrence of some modifications over the electrode interface before and after the hybridization event.

DNA↗
PubMed2000

Modeling splice sites with Bayes networks.

MOTIVATION: The main goal in this paper is to develop accurate probabilistic models for important functional regions in DNA sequences (e.g. splice junctions that signal the beginning and end of transcription in human DNA). These methods can subsequently be utilized to improve the performance of gene-finding systems. The models built here attempt to model long-distance dependencies between non-adjacent bases. RESULTS: An efficient modeling method is described which models biological data more accurately than a first-order Markov model without increasing the number of parameters. Intuitively, a small number of parameters helps a learning system to avoid overfitting. Several experiments with the model are presented, which show a small improvement in the average accuracy as compared with a simple Markov model. These experiments suggest that single long distance dependencies do not help the recognition problem, thus confirming several previous studies which have used more heuristic modeling techniques. AVAILABILITY: This software is available for downloaded and as a web resource at http://www.ai.uic.edu/software CONTACT: kasif@eecs.uic.edu

Bayes Theorem↗
PubMed2000

Association analysis of variants in the core promoter region of angiotensinogen gene with essential hypertension in Tibetan population.

OBJECTIVE: To detect the variants in the core promoter region of angiotensinogen(AGT) gene, and to analyse the relationship between the AGT gene polymorphisms and essential hypertension in Tibetan population. METHODS: This is a case-control study consisting of 103 essential hypertensive subjects and 82 normotensive controls matched by age and sex. The variants in the AGT gene core promoter region were screened by polymerase chain reaction/single strand conformation polymorphism(PCR/SSCP) and further identified by automated sequencing. The A(-6)G polymorphism was determined in DNA extracted from leucocytes by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). RESULTS: (1) There were two different electrophoresis band patterns in PCR/SSCP analysis. PCR product direct sequencing showed that the two band patterns represented the AA, AC genotypes in the (-20) site of AGT gene respectively. The distribution of A(-20)C genotype was almost identical in essential hypertensive and normotensive groups (P>0.8). The A allele frequency was very high in both groups (control: 0.9175, hypertensive: 0.9124). (2)Distribution of genotype in the (-6) site of AGT gene was much different between the patient group and control group (P<0.005). The frequency of G allele was statistically higher in the patient group than in controls (0.374 vs 0.220, P<0.025). CONCLUSION: Both Tibetan hypertensives and normotensives have higher frequency of A allele in AGT gene (-20) site. The higher frequency of G allele in the AGT gene (-6) site in Tibetan hypertension patients suggests that this allele may be the genetic susceptibility factor in the proceeding of essential hypertension in the Tibetan population.

Angiotensinogen↗
PubMed2000

Experimental study of the effect of external counterpulsation on blood circulation in the lower extremities.

A bidirectional ultrasonic Doppler flowmeter with direct single sideband separation was used to measure blood flow in the femoral and dorsalis pedis arteries of 18 normal volunteers. Changes in blood-flow velocity and volume during external counterpulsation (ECP) with various sustaining times (the time for maintaining pressure) for inflation were studied. The results showed that blood-flow velocity in the femoral and dorsalis pedis arteries is increased significantly by ECP, but the change is not closely related to the duration of inflation. For a short sustaining time, the net forward blood-flow volume in arteries increased remarkably, but at longer sustaining times it dropped back significantly to a value even lower than that before ECP. The sustaining time for inflation to produce the maximum net forward flow volume (the optimal sustaining time of inflation) was found to be at one-quarter to one-third of the cardiac cycle. In a second study, changes in the calibre of the femoral artery and its collateral and anastomotic branches in the hind extremities in 5 dogs before and after ECP with an optimal sustaining time of inflation were examined by femoral arteriography. The experiments showed that the patency of collateral and anastomotic branches of the femoral artery was greater before than after ECP. The study suggests that ECP could be an effective treatment for improving the blood circulation in extremities.

Adult↗
PubMed2000

Heroin abuse and nitric oxide, oxidation, peroxidation, lipoperoxidation.

To further reveal the risks of heroin abuse to human body, and to determine the injuries of oxidation, peroxidation and lipoperoxidation induced by nitric oxide and other free radicals to heroin abusers, we determined and compared plasma values of lipoperoxides (LPO), nitric oxide (NO), vitamin C (VC), vitamin E (VE), beta-carotene (beta-CAR) and erythrocyte values of LPO, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in 114 heroin abusers and 100 healthy volunteers. Using linear regression and correlation as well as stepwise regression and correlation, we also analyzed the effect of the abusing duration, and daily abusing quantity on the above-mentioned biochemical parameters in the heroin abusers. The results showed that, compared with the healthy volunteer groups, the average plasma values of LPO, and NO, and the average erythrocyte value of LPO in the heroin abuser group were significantly increased (P < 0.0001), and the average plasma values of VC, VE, and beta-CAR and the average erythrocyte values of SOD, CAT, and GSH-Px were significantly decreased (P < 0.0001). Analysis of linear regression and correlation showed that with prolonged heroin abusing and with increased daily quantity in the heroin abusers, the plasma values of LPO, and NO, and the erythrocyte value of LPO were gradually increased (P < 0.001), whereas the plasma values of VC, VE, and beta-CAR and the erythrocyte values of SOD, CAT, and GSH-Px were gradually decreased (P < 0.001). Analysis of stepwise regression and correlation indicated that the plasma values of NO, VC and VE were closely correlated with the abusing duration and daily abusing quantity. These results indicate that the balance between oxidation and antioxidation in the heroin abusers was seriously disturbed, and the injuries induced by nitric oxide and other free radicals, through oxidation, peroxidation and lipoperoxidation to the bodies of heroin abusers exacerbated. It is therefore necessary that in abstaining from heroin dependence, the heroin abusers should acquire sufficient quantities of antioxidants such as VC, VE and beta-CAR.

Ascorbic Acid↗
PubMed2000

[Analyses on the association of CA-repeat polymorphism and A1166-->C variant in the 3'-flanking region of AT(1)R gene with essential hypertension in Tibetans].

OBJECTIVE: To investigate whether CA-repeat polymorphism and A1166 --> C variant in the 3n-flanking region of AT(1)R gene are in association with the genetic susceptibily to essential hypertension (EH) in Tibetans. METHODS: A case-control study was carried out. Sibpair analysis and family linkage analysis were conducted. The CA-repeat polymorphism of AT &(1) R gene was identified by polymerase chain reaction(PCR) with fluorescence labeled dCTP as substrate and by semi-automatic sequence technology. The A1166 -->C variant was detected by PCR-RFLP. RESULTS: Association of AT&(1)R gene locus with EH was confirmed through the case-control study in well-characterized group of 113 Tibetan EH patients and 131 normotensives(chi(2)=26.44, P<0.001). A closer examination of this gene locus found 11 alleles from Tibetan population; allele A7 (138 bp) was more frequent in both the patients and the controls. Allele A8(140 bp) was in strong positive association with genetic susceptibility to EH in Tibetans. Frequency of allele A8 was 20.5% in EH and 7.3% in normotensives. The difference of allele frequencies between the groups was significant (chi(2)=9.64, P=0.002, OR=3.46, 95% CI 1.44-8.51). Affected sibpair analysis showed chi(2)=3.85, P=0.025; family linkage analysis gave Lod score of 0.80. No association between A1166 --> C variant in AT(1)R gene and EH in Tibetans was observed (P>0.05). CONCLUSION: The result suggests that CA-repeat polymorphism of AT(1)R gene be in association with EH in Tibetans, which implicates that AT(1)R gene may be in linkage disequilibrium with the causative genes of EH.

Adult↗
PubMed2000

[Protective effect of Ginaton on rat liver microcirculation disturbance following liver xenotransplantation].

OBJECTIVE: To study the effect of Ginaton on liver microcirculation disturbance following liver xenotransplantation in rats. METHODS: Ginaton was injected intravenously to recipients at a dosage of 14 mg/kg before graftng liver of guinea pigs. The portal blood flow (PBF) was measured by Doppler ultrasound at 0, 30 and 60 minutes after transplantation, and the pathologic changes of liver and heart were observed. RESULTS: The reperfusion status of control group was poor and leukocyte infiltration appeared in the center of lobute following transplantation and myocardial cells were impaired. Significant reduction in PBF was found in rats following transplantation. Ginaton pretreatment distinctly ameliorated PBF. The speed of PBF was closely correlated with the pathologic changes following transplantation. CONCLUSION: In the process of liver transplantation, ischemia reperfusion damage may lead to xenoheptic microcirculaton disturbance. Ginaton could improve the xenoheptic microcirculation and reduce ischemic reperfusion damage.

Animals↗
PubMed2000

[Effects of yanggan xifeng recipe on changes of neurological behavior of rat of Parkinson's model].

OBJECTIVE: To investigate the effect of Yanggan Xifeng Recipe (YGXFR) for nourishing Liver to calm down endogenous Wind on neurological behavior of Parkinson's disease (PD) rat model. METHODS: PD rat model was established by destroying the substantia nigra condense area (SNc) and ventral tegmental area (VTA) unilaterally with 6-hydroxy dopamine (6-OHDA). The rats for control were injected in the same site with the same dose of normal saline. The animals were randomly divided into 3 groups (7 in each group), the control group, the model group and the TCM treated group. Staircase test and rotation test induced by apomorphine were performed in all groups and compared. RESULTS: The staircase test demonstrated that, after being treated with YGXFR, the food pellets intake were increased compared to model group (P < 0.05), and their rotation induced by apomorphine was lessened (P < 0.01). CONCLUSION: YGXFR could recover the neurological behavior deficits of PD rat models.

Animals↗
PubMed1999

Spectral bifurcations in dispersive wave turbulence.

Dispersive wave turbulence is studied numerically for a class of one-dimensional nonlinear wave equations. Both deterministic and random (white noise in time) forcings are studied. Four distinct stable spectra are observed-the direct and inverse cascades of weak turbulence (WT) theory, thermal equilibrium, and a fourth spectrum (MMT; Majda, McLaughlin, Tabak). Each spectrum can describe long-time behavior, and each can be only metastable (with quite diverse lifetimes)-depending on details of nonlinearity, forcing, and dissipation. Cases of a long-live MMT transient state dcaying to a state with WT spectra, and vice-versa, are displayed. In the case of freely decaying turbulence, without forcing, both cascades of weak turbulence are observed. These WT states constitute the clearest and most striking numerical observations of WT spectra to date-over four decades of energy, and three decades of spatial, scales. Numerical experiments that study details of the composition, coexistence, and transition between spectra are then discussed, including: (i) for deterministic forcing, sharp distinctions between focusing and defocusing nonlinearities, including the role of long wavelength instabilities, localized coherent structures, and chaotic behavior; (ii) the role of energy growth in time to monitor the selection of MMT or WT spectra; (iii) a second manifestation of the MMT spectrum as it describes a self-similar evolution of the wave, without temporal averaging; (iv) coherent structures and the evolution of the direct and inverse cascades; and (v) nonlocality (in k-space) in the transferral process.

Atmosphere↗
PubMed1999

Isolation of a gene from Arabidopsis thaliana related to nematode feeding structures.

Using a promoter tagging approach, a gene upregulated in nematode feeding structures (NFS) of Heterodera schachtii was identified in Arabidopsis thaliana plants. Sequence analysis of the transgenic line bearing gus reporter gene and the wild-type plant revealed that the T-DNA had been inserted into the promoter of the gene, however, with transcription start points at different sites for the gus reporter gene and for the endogenous gene. This tagged gene, designated pyk20, encodes a transcript of 2.6 kb. Southern blot analysis revealed a single gene copy for pyk20 in the Arabidopsis C-24 genome. Other cruciferous plants were shown to possess pyk20 or homologous genes. The predicted amino acid sequence of the PYK20 protein contains 695 residues with a molecular mass of 78 kDa and includes a glutamine-rich domain in the C-terminal region. IAA and kinetin treatment increased the level of the pyk20 transcript in the plant, whereas ABA treatment and temperature stress reduced the pyk20 transcript level. In-situ hybridisation and Northern blot analysis revealed that the gene is expressed in NFS. Based on homologies of the glutamine-rich domain, the biological role of the pyk20 gene product as a transcription factor is assumed.

Amino Acid Sequence↗
PubMed1999

AND-34, a novel p130Cas-binding thymic stromal cell protein regulated by adhesion and inflammatory cytokines.

We have characterized a novel cDNA whose steady state mRNA levels rise in the thymus 2 to 6 h following the induction of CD4+CD8+ thymocyte apoptosis by in vivo cross-linking of CD3 epsilon. This cDNA, AND-34-1, contains an open reading frame (ORF) encoding a protein with an amino-terminal Src homology 2 (SH2) domain and a carboxyl-terminal domain homologous to GDP-exchange factors (GEFs). Northern analysis demonstrates widespread expression of the AND-34 gene. Anti-CD3 epsilon treatment induces up-regulation of the AND-34 mRNA levels in total thymic RNA but not in RNA from purified thymocytes, suggesting that this transcript is derived from a thymic stromal cell population. IL-1 and TNF increase AND-34 transcript levels in thymic cortical reticular, thymic nurse, and fibroblast cell lines. In the thymic cortical reticular cell line, IL-1 and TNF induce a protein of the predicted 93-kDa size reactive with anti-AND-34 peptide antisera. Fifteen minutes of serum stimulation of vanadate-pretreated AND-34-1-transfected NIH3T3 fibroblasts induces tyrosine phosphorylation of AND-34 as well as coprecipitating 95-, 125-, and 130-kDa proteins. One of these tyrosine phosphorylated proteins is identified as p130Cas (Crk-associated substrate), a signaling molecule previously known to bind to a GDP-exchange factor (C3G) and inducibly associate with the focal adhesion complex. Consistent with such an association, AND-34 tyrosine phosphorylation is induced following adherence of trypsinized fibroblasts to fibronectin or poly-L -lysine-coated surfaces.

3T3 Cells↗
PubMed1999

Prior exposure to neurotrophins blocks inhibition of axonal regeneration by MAG and myelin via a cAMP-dependent mechanism.

MAG is a potent inhibitor of axonal regeneration. Here, inhibition by MAG, and myelin in general, is blocked if neurons are exposed to neurotrophins before encountering the inhibitor; priming cerebellar neurons with BDNF or GDNF, but not NGF, or priming DRG neurons with any of these neurotrophins blocks inhibition by MAG/myelin. Dibutyryl cAMP also overcomes inhibition by MAG/myelin, and cAMP is elevated by neurotrophins. A PKA inhibitor present during priming abrogates the block of inhibition. Finally, if neurons are exposed to MAG/myelin and neurotrophins simultaneously, but with the Gi protein inhibitor, inhibition is blocked. We suggest that priming neurons with particular neurotrophins elevates cAMP and activates PKA, which blocks subsequent inhibition of regeneration and that priming is required because MAG/myelin activates a Gi protein, which blocks increases in cAMP. This is important for encouraging axons to regrow in vivo.

Animals↗
PubMed1999

[A method for preparation of carbon fiber electrode].

Carbon fiber electrode (CFE) can be used in detection of exocytosis of single neuron or endocrine cell. A simplified method for preparation of CFE, as described in the present paper, greatly ensures the coordination and success of the preparation. Such CFEs have a low noise level. Exocytosis of rat adrenal chromaffin cells was investigated in the clarification of the effect of MPP+ on transmitter release. It is found that exocytosis was not stimulated by MPP+ and the high K+ induced secretion was not changed by MPP+. These observations suggest that the previously reported elevation of dopamine content in the surrounding histosolution of DA neuron is probably resulted from blockage of the re-uptake of DA by MPP+.

1-Methyl-4-phenylpyridinium↗
PubMed1999

[Effect of regulation of kidney-yin and kidney-yang on hypothalamus-pituitary-adrenal-thymus axis in monosodium L-glutamate rats].

OBJECTIVE: To study the interrelationship between hypothalamus-pituitary-adrenal-thymus (HPAT) axis and Kidney-Yang and Kidney-Yin in arcuate nucleus destroyed rats. METHODS: Monosodium glutamate (MSG) 4 mg/g body weight was given subcutaneously to neonatal rats at 2, 4, 6, 8 and 10th day after born to destroy the ARC, and Zuogui pill or Yougui pill (5 g/kg daily) was given respectively by gastrogavage when the model rats entered adulthood. RESULTS: Immunohistochemical staining showed that in the model group the number of corticotropin-releasing hormone (CRH) positive neurons in hypothalamic paraventricular nucleus and anterior pituitary adrenotrophin (ACTH) positive secretory cells, which stained deeply, were more than those in the control group, the adrenal fasciculate zone disturbed with increased cells and obviously dilated sinusoid. The thymus atrophied with lymphocyte proliferation apparently lower, blood corticosterone, ACTH content and hypothalamic CRF level higher in the model than those in the control. Zuogui pill could improve above-mentioned pathophysiologic changes effectively but Yougui pill could not. CONCLUSION: Process of pathophysiology of HPA axis hyperfunction accompanied cell-mediated immunodeficiency may belong to the category of Kidney-Yin Deficiency Syndrome.

Animals↗