Biomedical subjects

J Ye

Publications and source records attributed to J Ye.

At least 163 records · Page 9Linked to original sources

PubMed1999

[Mutation in the promoter region of 21-hydroxylase gene of patients with congenital adrenal hyperplasia].

OBJECTIVE: To investigate the mutations in the 21-hydroxylase gene promoter region of patients with congenital adrenal hyperplasia (CAH). METHODS: The authors amplified a 1.6 kb fragment of the CYP21 gene which was confirmed by endonuclease digestion. The PCR product was re-amplified with promoter-region-specific primers. The amplified fragments were analyzed using SSCP and endonuclease digestion methods. RESULTS: Among 12 patients, 6 patients presented an abnormal band on SSCP analysis. By endonuclease digestion test, the authors found a patient who presented one mutation in KpnI recognition site located in the CK-2 (-101) binding region and one in Taq I recognition site located -201. These mutations were confirmed by sequencing. CONCLUSION: Novel mutations were found in the promoter of 21-hydroxylase gene in CAH patients and the findings spurred on further expression studies.

Adrenal Hyperplasia, Congenital↗

PubMed1999

Regulation of endoplasmic reticulum cholesterol by plasma membrane cholesterol.

The abundance of cell cholesterol is governed by multiple regulatory proteins in the endoplasmic reticulum (ER) which, in turn, are under the control of the cholesterol in that organelle. But how does ER cholesterol reflect cell (mostly plasma membrane) cholesterol? We have systematically quantitated this relationship for the first time. We found that ER cholesterol in resting human fibroblasts comprised approximately 0.5% of the cell total. The ER pool rose by more than 10-fold in less than 1 h as cell cholesterol was increased by approximately 50% from below to above its physiological value. The curve describing the dependence of ER on plasma membrane cholesterol had a J shape. Its vertex was at the ambient level of cell cholesterol and thus could correspond to a threshold. A variety of class 2 amphiphiles (e.g., U18666A) rapidly reduced ER cholesterol but caused only minor alterations in the J-curve. In contrast, brief exposure of cells to the oxysterol, 25-hydroxycholesterol, elevated and linearized the J-curve, increasing ER cholesterol at all values of cell cholesterol. This finding can explain the rapid action of oxysterols on cholesterol homeostasis. Other functions have also been observed to depend acutely on the level of plasma membrane cholesterol near its physiological level, perhaps reflecting a cholesterol-dependent structural or organizational transition in the bilayer. Such a physical transition could serve as a set-point above which excess plasma membrane cholesterol is transported to the ER where it would signal regulatory proteins to down-regulate its further accumulation.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed1999

[The characteristic wave intervals of exercise ECG influenced by changing of heart rate].

This paper analyzes the characteristic wave intervals of exercise ECG influenced by heart rate changing under exercise test. The most influenced parameter is TP interval, the next is QT interval, and the width of P wave and QRS waves are nearly unchanging. According to the changing characteristic of these waves width mentioned above, we suggest an adaptive adjusting method for ST segment measuring position after the J point, which is of significance to recognizing the characteristic waves and determining the result of exercise test for myocardial ischemia.

Adult↗

PubMed1999

[Purification and properties of human lysozyme in engineered bacterium E. coli].

To obtain the SDS-PAGE-pure human lysozyme, the crude enzyme of engineered bacterium E. coli was purified by chromatography on cation ion exchange of Express-Ion S. The optimum reaction temperature and pH of this lysozyme were 45 degrees C and 6.5, respectively. The isoelectric point is pH 8.91, and Km of the enzyme for Micrococcus lysodeikticus is 0.0311 mg/mL. The thermal stability of the engineered enzyme is more sensible than hen egg white lysozyme and human milk lysozyme. The sequence of 5 amino acids in N-end is same as designed, except an Met at the first. The affects of some metal ion on this enzyme were shown. Cu2+ of 0.01 mmol/L could completely inactivate the enzyme.

Amino Acid Sequence↗

PubMed1999

[Establishment of transformation system of Streptomyces lincolnensis].

Transformation system of S. lincolnensis was established to improve lincomycin--producing strains by Gene retransformation Technology. Under optimal conditions, 10(11) protoplasts were prepared from 25 ml SM culture medium, and the regeneration frequency of protoplasts was 16%. The transformation frequency of pIJ702 was up to 5.5 x 10(5)/microgram DNA. The results revealed that gene manipulation in S. lincolnensis was facile as that in S. lividans.

Culture Media↗

PubMed1999

[Preparation, purification and identification of sialic acid from Escherichia coli C-8].

Colominic acid produced from Escherichia coli C-8 was purified by ammonia sulfate precipitation, dialysis and concentration. After hydrolysis of colominic acid at a pH of 2.5, at 70 degrees C for 4 h, sialic acid was obtained, then purified by chromatography on Dowex1-x8. Analysis of thin-layer chromatography and absorption spectrum of sialic acid in the orcinol/Fe3+/HCl and the periodic acid/thiobarbituric acid confirmed that its purity was identical with that of standard sample.

Chromatography, Thin Layer↗

PubMed1999

[Culture conditions of engineered strain of L-asparaginase and the recombinant plasmid stability].

The growth curves of engineered strain JM105(pASN) were different in LB and M-3 media. The expression level and activity of L-asparaginase were affected apparently by both biomass and induction time. Glucose repression of production of L-asparaginase was found. The stability of the recombinant plasmid pASN in different host strains and in LB and M-3 media was determined. After cultivation inLB broth and M-3 media at 30 degrees C for more than 50 generations without antibiotic selection, then induced at 42 degrees C for up to 5 h, the engineered strains were proved to be stable, except for DHA alpha (pASN).

Asparaginase↗

PubMed1999

[The effect of granule-rhinitis on allergic nasal mucosa].

OBJECTIVE: To investigate the effect of granule-rhinitis on allergic rhinitis. METHOD: Experimental guinea pigs with allergic rhinitis were treated with granule-rhinitis. During the total course of treatment, sneezing and nasal itching were observed and recorded and then compared quantitatively with those of the control groups. Histological changes of the nasal mucosa were observed. RESULT: The various symptoms of allergic rhinitis were obviously relieved in the treatment group. Granule-rhinitis reduced inflammatory cell infiltration, particularly decreased the number of mast cells and eosinophils in the superficial layers of the nasal mucosa, and reduced the release of mediators from mast cells. It diminished the vasodilatation in nasal mucosa. CONCLUSION: Granule-rhinitis is effective in the treatment of allergic rhinitis.

Animals↗

PubMed1999

[Study on the posterior vitreous detachment in patients with high myopia].

OBJECTIVE: To access the development of posterior vitreous detachment(PVD) related to age, axial length of the eye, vitreous changes as well as the myopic chorioretinal manifestation in patients with high myopia. METHODS: The vitreous status of 61 consecutive patients with high myopia(> or = -8.0 D and axial length > or = 26.0 mm) 110 eyes and 68 controls (< or = -3.0 D) 119 eyes were examined with biomicroscopic slit lamp and B-scan ultrasound. The myopic chorioretinal changes at the posterior pole were examined by indirect ophthalmoscope. The axial length of the eye was measured by A-scan ultrasound. The incidence of PVD was evaluated by Chi-square test. RESULTS: The incidence of PVD in patients with high myopia increased with age. Its overall incidence was significantly higher than that in the controls (78.2% vs 31.1%, P < 0.001). In addition, the onset of PVD in patients with high myopia occurred much earlier in age than that in the control group. Axial length was an important factor responsible for the development of PVD in patients with high myopia. The incidence of PVD and age were highly correlated (r = 0.9997, P < 0.05). Retinal detachment occurred in 5 eyes in the patients with high myopia. CONCLUSIONS: The results in the present study suggested that the incidence of PVD in patients with high myopia, increased with axial length of the eye and age. Vitreous changes are characteristic findings associated with high myopia, which was also involved in the development of PVD.

Adult↗

PubMed1999

[The method of wavelet transformation used for extracting the characteristic of the exercise ECG].

This article introduces the basic rationale of wavelet transformation and the algorithm of typical dyadic wavelet transformation with mother wavelet of the first derivative of a Gaussian smoothing function, this wavelet transformation is used to recognize the characteristic parameters of the exercise ECG, it is concluded that this method make significant effects on restricting base line drifting and lessening noisy component in the exercise ECG, it provides a new way to do further research on characteristic recognition of the exercise ECG in the exercise test.

Algorithms↗

PubMed1998

Retrograde cerebral perfusion results in flow distribution abnormalities and neuronal damage. A magnetic resonance imaging and histopathological study in pigs.

BACKGROUND: In the past few years, although significant efforts have been made to assess flow distribution during retrograde cerebral perfusion with microspheres, dye, or hydrogen clearance, flow distribution in real time is still undefined. We used MR perfusion imaging to monitor flow distribution in the brain during and after deep hypothermic circulatory arrest (DHCA) with antegrade or retrograde cerebral perfusion (ACP or RCP). METHODS AND RESULTS: Thirteen pigs were divided into 2 groups and exposed to 120 minutes of either RCP (n = 7) or ACP (n = 6) at 15 degrees C, followed by 60 minutes of cardiopulmonary bypass (CPB) at 37 degrees C. During DHCA, the brain was perfused antegradely through the common carotid artery or retrogradely through the superior vena cava at pressures of 60 to 70 mm Hg and 20 to 25 mm Hg in the ACP and RCP groups, respectively. Esophageal temperature was monitored continuously. MR perfusion images were acquired every 30 minutes before, during, and after DHCA. The brain was perfusion-fixed with formaldehyde solution for histopathology at the completion of each experiment. During initial normothermic CPB, MR perfusion imaging showed a nearly uniform distribution of flow in the brain. The same pattern was maintained with a significant increase in regional cerebral blood volume during ACP and reperfusion in the ACP group. RCP provided little or no detectable blood distribution to the brain, resulting in poor reperfusion of many areas of the brain on reflow with CPB at 37 degrees C. The total area suffering poor reperfusion was significantly higher in the RCP group than the ACP group. Histopathology showed no morphological changes in any area of the brain in the ACP group, whereas varying severity of neuronal damage was observed in different regions of the brain in the RCP group. CONCLUSIONS: ACP preserves uniform blood distribution and normal morphology of brain tissue after prolonged DHCA. RCP provides very little blood to the tissue of the brain. A 120-minute period of RCP results in abnormal flow distribution and neuronal damage during reperfusion. The damage resulting from shorter periods of RCP remains to be assessed.

Animals↗

PubMed1998

Circulation of cholesterol between lysosomes and the plasma membrane.

The cholesterol in the lysosomes of cultured human fibroblasts was determined to constitute approximately 6% of the cell total. This pool was enlarged by as much as 10-fold in Niemann-Pick type C cells. Certain amphiphiles (e.g. U18666A, progesterone, and imipramine) caused lysosomal cholesterol to increase to similarly high levels at a rate of approximately 0.8% of cell cholesterol/h. Lysosomal cholesterol accumulated even in the absence of exogenous lipoproteins. Furthermore, nearly all of the lysosomal cholesterol in both of the two perturbed systems was shown to be derived from the plasma membrane. Oxysterols known to alter cholesterol movement and homeostasis blocked lysosomal cholesterol accretion in amphiphile-treated cells, suggesting that this process is regulated physiologically. Treating cells with amphiphiles slightly reduced the efflux of cholesterol from lysosomes and slightly increased the influx from the plasma membrane, causing the lysosomal cholesterol compartment to double in size in approximately 15 h. After more prolonged amphiphile treatments, a population of buoyant lysosomes appeared that exchanged cholesterol with the plasma membrane completely but slowly. Niemann-Pick type C lysosomes were similarly buoyant and sluggish. We conclude that cholesterol circulates bidirectionally between the plasma membrane and lysosomes. The massive accumulation of lysosomal cholesterol in the perturbed cells does not appear to reflect disabled lysosomal transport but rather the formation of lysosomes modified for lipid storage, i.e. lamellar bodies.

Androstenes↗

PubMed1998

Cloning of the human tissue inhibitor of metalloproteinase-4 gene (TIMP4) and localization of the TIMP4 and Timp4 genes to human chromosome 3p25 and mouse chromosome 6, respectively.

We have isolated genomic DNA containing the human tissue inhibitor of metalloproteinases-4 gene (TIMP4) and determined the structure of the exons comprising the gene. Like other members of the TIMP family, the TIMP-4 protein is encoded by five exons. These span 6 kb of genomic DNA, so that TIMP4 is similar in size to Timp1 but considerably smaller than TIMP2 and TIMP3. The exon-intron boundaries of TIMP4 are at locations very similar to those of the other TIMP genes, demonstrating the high degree of conservation of gene structure in this family. The human and mouse TIMP-4 genes map to comparable locations in the respective genomes, localizing to human chromosome 3p25 and mouse chromosome 6.

Animals↗

PubMed1998

Morphological and molecular changes of maize plants after seeds been flown on recoverable satellite.

Dry seeds of Zea mays, heterozygous for Lw1/lw1 alleles, sandwiched between nuclear track detectors aboard Chinese satellite for 15 days, were recovered and mutations in morphological characters on plants developed from these seeds, as well as their selected progenies, were investigated. The dosimetric results indicated that 85% of the seeds received at least 1 hit with Z > or = 20. About 10% of plants developed from flown seeds and 40% of observed selfed lines from the first generation plants showed some morphological changes, such as yellow stripes displayed on leaves, dwarf, anomogensis of floral organs and yellow-green seedlings, when compared with those from ground control. Using yellow stripes on leaves as the main endpoint for evaluating mutation induced in space environment, the frequency of stripe occurrence was 4.6% in the first generation plants, comparable with the results obtained from Long Duration Exposure Facility (LDEF) mission (Mei et al., 1994), but much lower than those from ground based 60 Co-gamma treatment at a dose of 100 Gy, which reached 35.5% in the selfed lines of the second generation. One hundred and ten random primers were screened in RAPD analysis to detect the variation on genomic DNA of plants with stripes on leaves. Of these primers, 10.9% were able to generate polymorphic bands between mutated plants and control, also, common band patterns in several progenies with the same mutation phenotype were observed. These results demonstrated that space radiation environment could induce inheritable mutagenic effects on plant seeds, and verified the change in genetic material in the mutants. Further study will be needed for a better understand of the nature and mechanism of this induction of mutation.

Cobalt Radioisotopes↗

PubMed1998

Quantitative cardiac SPECT in three dimensions: validation by experimental phantom studies.

A mathematical framework for quantitative SPECT (single photon emission computed tomography) reconstruction of the heart is presented. An efficient simultaneous compensation approach to the reconstruction task is described. The implementation of the approach on a digital computer is delineated. The approach was validated by experimental data acquired from chest phantoms. The phantoms consisted of a cylindrical elliptical tank of Plexiglass, a cardiac insert made of Plexiglass, a spine insert of packed bone meal and lung inserts made of styrofoam beads alone. Water bags were added to simulate different body characteristics. Comparison between the quantitative reconstruction and the conventional FBP (filtered backprojection) method was performed. The FBP reconstruction had a poor quantitative accuracy and varied for different body configurations. Significant improvement in reconstruction accuracy by the quantitative approach was demonstrated with a moderate computing time on a currently available desktop computer. Furthermore, the quantitative reconstruction was robust for different body characteristics. Therefore, the quantitative approach has the potential for clinical use.

Body Composition↗

PubMed1998

Developmental expression and characterization of the alpha2,8-polysialyltransferase activity in embryonic chick brain.

The alpha2,8-polysialyltransferases (polySTs) from embryonic chick brain catalyze the alpha2,8-specific polysialylation of endogenous neural cell adhesion molecules (N-CAMs). This posttranslation glycosylation decreases N-CAM-dependent cell adhesion and migration. The enzymatic properties of the membrane-bound form of the polyST activity was investigated in vitro. Our results show that the polyST activity was developmentally expressed with maximum specific activity appearing about 12 days after fertilization. This time shortly precedes maximal expression of the cognate polysialylated N-CAMs. Kinetic studies showed the KMand Vmaxfor CMP-Neu5Ac were 133 microM and 0.13 microM/h, respectively, at pH 6.1, 33 degrees C. CMP-Neu5Gc was not a donor substrate. PolyST activity was increased 5- to 6-fold in the presence of 10 mM MnCl2,the preferred divalent cation, and 1 mM dithiothreitol (DTT). Heparin (3 kDa) was a noncompetitive inhibitor of polysialylation with a Kiof 9 microM. Based on the affinity of the enzyme for heparin, the polyST activity was partially purified ( approximately 30-fold) by heparin-Sepharose affinity chromatography, after differential solubilization with the zwitterionic detergent, CHAPS. DTT and chemical modification studies using the thiol-directed alkylating reagents, N-ethylmaleimide (NEM) and iodoacetamide (IAA), were used to show that at least one cysteinyl residue in the polyST was of critical importance for polysialylation, but of lesser importance for monosialylation, catalyzed by the alpha2,3-, alpha2,6-, and alpha2,8-monosialyltransferases (monoSTs). A sulfhydryl residue is implicated in chain initiation. Two important structural differences between the mono- and polySTs were revealed by sequence analyses. First, the polySTs contain heparin-like, positively charged amino acid clusters upstream of both sialylmotif L and S. Second, the polySTs contain a uniquely extended basic amino acid region (pI 11. 6-12.0) of 31 residues immediately upstream of sialylmotif S. This extended, positively charged region may function in the processive mechanism of polymerization by allowing nascent polySia chains to remain bound to the polyST during the repetitive addition of each new Sia residue to the nonreducing termini of the growing chain. The importance of these studies is that they provide new information on the enzymatic basis of polysialylation. They also reveal that sulfhydryl residues and extended basic amino acid domains are two structural features unique to polysialylation, in contrast to monosialylation. Both may be important distinguishing features between the classes of distributive (monoSTs) and processive polysialyltransferases, which have not been previously described.

Alkylating Agents↗

PubMed1998

A protective role for heme oxygenase expression in pancreatic islets exposed to interleukin-1beta.

Heme oxygenase (HO)-1 expression was investigated in rat isolated pancreatic islets. Freshly isolated islets showed no evidence of HO-1 expression. After a 20-h culture, there was a small increase in HO-1 in control islets, and interleukin-1beta (IL-1beta) induced HO-1 expression above control levels. N(G)-monomethyl-L-arginine inhibited the IL-1beta-induced increase in HO-1. Sodium nitroprusside-generated nitric oxide also increased HO-1 expression. CoCl2 induced a concentration- and time-dependent increase in HO-1, but not heat shock protein 70, expression. Cobalt chloride (CoCl2) protected islets from the inhibitory effects of IL-1beta on glucose-stimulated insulin release and glucose oxidation. Nickel chloride did not mimic the effects of CoCl2. An inhibitor of HO-1 activity, zinc-protoporphyrin IX (ZnPP), prevented the protective effect of CoCl2 on insulin release with IL-1beta but did not affect HO-1 expression or the inhibitory response to IL-1beta alone. ZnPP also inhibited the protective effect of hemin in IL-1beta-treated islets. CoCl2 inhibited the marked increase in islet nitrite production in response to IL-1beta. Cobalt-protoporphyrin IX (CoPP), which increased HO expression and activity, also protected islets from the inhibitory effects of IL-1beta, even though IL-1beta largely blocked the CoPP-induced increase in HO-1 expression. In betaHC9 cells, CoCl2 increased HO-1 expression and HO activity, whereas CoPP directly activated HO. ZnPP inhibited basal and CoCl2-stimulated HO activity. Thus, increased HO-1 expression and/or HO activity in response to CoCl2, CoPP, and hemin, seems to mediate protective responses of pancreatic islets against IL-1beta. HO-1 may be protective of beta-cells because of the scavenging of free heme, the antioxidant effects of the end-product bilirubin, or the generation of carbon monoxide, which might have insulin secretion-promoting effects and inhibitory effects on nitric oxide synthase.

Animals↗

PubMed1998

Lack of seasonality in the month of onset of childhood IDDM (0.7-15 years) in Shanghai, China.

A cohort of 136 children from Shanghai with insulin dependent diabetes mellitus (IDDM) (0.7-15 years) were analyzed for the month of onset of disease and month of birth. In contradistinction to populations with a medium or high incidence of IDDM, no seasonality was registered in the month of onset. On the other hand there was a significant (p < 0.026) seasonality in the month of birth (peak November to January), but which differed in pattern to that observed in populations with medium or high incidence. Our findings support the hypothesis that the initiation of IDDM is due to a viral infection and that one cause for the low incidence of childhood IDDM in certain populations is immunization against infectious pathogens in their early life.

Adolescent↗