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Biomedical subjects

L Ye

Publications and source records attributed to L Ye.

At least 55 records · Page 3Linked to original sources
PubMed2000

Liquid chromatographic analysis of all-trans-retinyl palmitate, beta-carotene, and vitamin E in fortified foods and the extraction of encapsulated and nonencapsulated retinyl palmitate.

A liquid chromatographic method is described for the analysis of natural vitamin E homologues, all-rac-alpha-tocopheryl acetate, retinyl palmitate (encapsulated and nonencapsulated), and beta-carotene in various fortified foods. The vitamins are extracted in 2-propanol and hexane without saponification and quantitated by normal phase chromatography with fluorescence and visible detection. The sample components were identified using an on-line three-dimensional photodiode array detector, which permitted profiling of the 190-800 nm absorption spectrum of any chromatographic peak. The method showed linearity for the analytes in their respective calibration ranges. The percent recoveries for retinyl palmitate using starch- and gelatin-encapsulated standards were 101.0 +/- 1.0 and 100.1 +/- 0.9, respectively. The method measures six or more analytes in a single injection and differentiates between natural and synthetic forms of vitamin E.

Chromatography, Liquid↗
PubMed2000

Mutational analysis of the modulation of tyrosinase by tyrosinase-related proteins 1 and 2 in vitro.

The albino (tyrosinase, Tyrc), brown (tyrosinase-related protein 1, Tyrp1b) and slaty (tyrosinase-related protein 2, tyrp2slt) loci are all involved in the regulation of melanogenesis. Phenotypes of inbred mice mutant at two or more of these loci are not always explicable by simple summation of the established or suspected catalytic functions of the gene products. These phenotypes suggest that relationships among the proteins extend beyond the obvious fact that they catalyze different steps in the same melanogenic pathway, and that they may also interact intimately in such a way that a mutation in one impacts the function of the other(s). Previous studies have attributed catalytic activities to each member of this trio; however, it has been difficult to study the proteins individually, either in vivo or in tissues or cells. Therefore, we undertook to transfect the genes, in revealing combinations, into COS-7 cells (which have no melanogenic apparatus of their own) to clarify the interacting functions of their encoded proteins. Specifically, we attempted to evaluate the effects of Tyrp1 and Tyrp2 proteins on tyrosinase protein. We report evidence that Tyrp1 stabilizes tyrosinase, confirming previous observations, and, in addition, demonstrate that Tyrp1 decreases tyrosinase activity. By contrast, Tyrp2 increases tyrosinase activity by stabilizing the protein. We conclude that both Tyrp1 and Tyrp2, in addition to other catalytic functions they may possess, act together to modulate tyrosinase activity.

Animals↗
PubMed2000

A unique 33-kD cysteine proteinase accumulates in response to larval feeding in maize genotypes resistant to fall armyworm and other Lepidoptera.

Plants respond to insect feeding with a number of defense mechanisms. Using maize genotypes derived from Antiquan germ plasm that are resistant to Lepidoptera, we have demonstrated that a unique 33-kD cysteine proteinase accumulates in the whorl in response to larval feeding. The abundance of the proteinase increased dramatically at the site of larval feeding after 1 hr of infestation and continued to accumulate for as long as 7 days. The 33-kD cysteine proteinase was most abundant in the yellow-green portion of the whorl-the normal site of larval feeding and the tissue that has the greatest inhibitory effect on larval growth in bioassays. The proteinase was expressed in response to wounding and was found in senescent leaves. It may be a marker of programmed cell death. The gene coding for the proteinase, mir1, has been transformed into Black Mexican Sweet callus. When larvae were reared on callus expressing the proteinase, their growth was inhibited approximately 60 to 80%. The expression of a cysteine proteinase, instead of a cysteine proteinase inhibitor, may be a novel insect defense mechanism in plants.

Animals↗
PubMed2000

[Measurement of T and DHT contents in normal and diseased human prostate tissues].

OBJECTIVE: To measure T and DHT contents in normal and diseased human prostate tissues. METHODS: Serum and prostatic T and DHT levels were measured in patients with normal, benign prostatic hyperplasia and prostate cancer. RESULTS: A decline was observed in serum T level, but no change in DHT concentration with aging. There were no significant differences in both blood T and DHT levels between the patients with BPH or PCA and normal controls. Serum T level remained constant. There were excessive accumulation of DHT in BPH, and cancerous prostate tissues were responsible for the pathogenesis of BPH and PCA. Finasteride treatment did not produce a reduction in prostatic DHT content. CONCLUSION: More than one form of 5a-reductases is responsible for the high level of DHT in the gland.

Adult↗
PubMed2000

[Survival analysis after kidney transplantation in 1,180 cadaveric graftings].

OBJECTIVE: To analyze the outcome of twenty-two years of cadaveric kidney transplantation and the predict factors impacting on graft survival. METHODS: The data of 1,180 cadaveric kidney graftings in 1,039 patients between October of 1977 and June of 1999 were summarized by calculation of patient and graft survival rates using Kaplan-Meier product limit estimates. 13 factors that may influence on graft survival were analyzed by the log-rank and Cox model. RESULTS: The total of 1-, 5-, 10-, 15-, and 20-year patient survival rates were 93.02%, 80.25%, 67.86%, 65.34% and 65.34%, and the corresponding graft survival rates 88.6%, 68.3%, 43.8%, 43.8%, and 32.8%, respectively. Graft half-life was (13.98 +/- 0.96) years. The longest survivor was 22 years after cadaveric kidney transplantation. The quality of life after grafting in 835 alive patients was improved apparently; 95% of them had a normal graft function and 85% returned to work. The result of multivariable analysis using Cox model showed that 8 factors of patient's age, grafting time, pretransplant blood transfusion, cold ischemia time, delayed graft function, time of normal graft function, immunosuppressive regimen, and acute rejection were very important to affect the graft survival. CONCLUSION: Cadaveric kidney transplantation is a successful and effective method to rescue the patients with end-stage renal disease.

Adolescent↗
PubMed2000

[The diel rhythm of PGE2 in blood of the growing rat after retractive force on mandible].

OBJECTIVE: To study whether the orthopedic therapy will affect the rat's metabolism, the author investigates the diel rhythm of PGE2 in blood of the growing rats before and after retractive force on mandible. METHODS: 72 rats which were 4 weeks old and about 90 g, were divided equally and randomly into three groups: the contrast group were not exerted force, the daytime-forced group were exerted force from 8:00 am to 20:00 pm, the nighttime-forced group were exerted force from 20:00 pm to 8:00 am of the next morning. The backwards force imposed on the rats were exerted through the center of the mandibular condyle and was about 40 g(0.4 N). The period of experimentation was 7 days. In the 8th day, every 4 rats from each of the group were killed respectively at 0:00, 4:00, 8:00, 12:00, 16:00 and 20:00 to collect 3 ml blood. Then radioimmunoassay methods were used to measure the concentration of PGE2 in the blood. RESULTS: In natural state, there was a diel rhythm in the concentration of PGE2 in rats' blood and the diel rhythm was related to that of endogenous PGE2 in condyle; After imposed orthopedic force to restrain mandibular growth, the normal diel rhythm of PGE2 in blood disappeared. There was no significant difference in the time-concentration curves between the contrast group and the daytime-forced group (P > 0.05), but the difference between the contrast group and the nighttime-forced group was obvious (P < 0.05) and the mesor of the nighttime-forced group was greatly decreased. CONCLUSION: The concentration of PGE2 in rats' blood will not be affected by the orthopedic force in daytime, in nighttime. For this reason, not only the therapeutic effect but also the effect on the body's metabolism should be considerd in clinical therapy, and further researches should be carried out on whether the local orthopedic force would influence the metabolism of the whole body.

Animals↗
PubMed2000

[Circadian rhythm changes of the levels of endogenous insulin in growing rat's blood after functional mandibular protrution].

OBJECTIVE: In order to determine whether the metabolism of the body can be influenced by local functional orthopedic treatments and the relationship between the proliferation and translation of condyle and the metabolism of the body, the author investigates the circadian rhythm of the levels of endogenous insulin (Ins) in growing rats' blood and the changes after functional mandibular protrusion in daytime (8:00-20:00) or nighttime (20:00-8:00). METHODS: 72 4-week-old SD rats were divided equally and randomly into experimental and control groups, and the rats in experimental groups were put on the functional appliances in daytime (8:00-20:00) or nighttime (20:00-8:00). After 7 days, all rats were sacrificed at 0:00, 4:00, 8:00, 12:00, 16:00, 20:00 in a day. Radioimmunoassay methods wore used to detect the levels of endogenous insulin in growing rats' blood in every four hours of a day. RESULTS: 1. The growing rats' blood displayed a significant circadian rhythm in the levels of endogenous insulin, the acrophase was about 13:02. 2. The circadian rhythm still existed after used functional appliance. No significant changes (both mesors and amplitudes) had been observed in the experimental groups comparing with the control groups. 3. The circadian rhythm of insulin in blood concerned with that of endogenous insulin in condyle. CONCLUSION: 1. The metabolism of the body can not be influenced by local functional orthopedic treatments. 2. The proliferation and translation of condyle concern with the metabolism of the body.

Animals↗
PubMed2000

[Amplification, cloning and expression of a gene encoding hexose transporter of Plasmodium falciparum].

OBJECTIVE: To amplify, clone and express of a gene encoding hexose transporter of Plasmodium falcipuram (PfHT1) from Southern China isolate FCC1/HN for studing the immune of recombinant which protective from malaria parasite infection. METHODS: Cultivation of P. falciparum isolate FCC1/HN in vitro; extraction of genomic DNA from FCC1/HN using the alkali specific cleavage method; PCR amplification of PfHT1 and cloning into eukaryotic expression vector, pEGFPN3. The recombinant as introduced into mammalian cells, HEPG2 by using liposome-mediated transfection. RESULTS: The gene encoding PfHT1 was specifically amplified from the genomic DNA of P. falciparum isolate FCC1/HN. The size of amplified fragment was 1,516 base pair. The eukaryotic expression recombinant, pN3-HT1, was constructed and expressed steadily in the hepatocarcinoma cell lines, HEPG2. CONCLUSION: The gene encoding PfHT1 was successfully amplified and cloned. The pN3-HT1/HEPG2 cell line was built for expressing fusion protein of GFP-HT1.

Animals↗
PubMed2000

[Study on the volatile oil of Nardostachys chinensis].

The volatile oil of Nardostachys chinensis Batal has been studied by GC-MS, and 21 compounds have been isolated and identified. The total content of the components are 88.51%. Major compounds have been identified as Calarene (29.44%). delta 1(10)-Aristolenone-2 (16.57%) and Jatamansinol (8.80%).

Gas Chromatography-Mass Spectrometry↗
PubMed2000

[Experimental studies on the diel rhythm changes of blood cAMP in growthing rats after mandibular retraction].

OBJECTIVE: To document the effect of orthopedic therapy on the metabolism of rats. METHODS: Exerting backwards force on rats mandible and measuring concentration of rats' blood cAMP in three groups with radio-immunity. Drawing the time-concentration curve and making cosine analysis. RESULTS: In natural state, there was a diel rhythm change of concentration of cAMP in rats' blood(P<0.05); After being imposed orthopedic forces to inhibit mandibular growth, the normal diel rhythm of cAMP in blood still existed(P<0.05). The results of parameter-comparison among groups were more complicated. CONCLUSION: Further research is needed to clarify the mechanism whether local orthopedic forces influence the body metabolism.

English Abstract↗
PubMed1999

Suppressive action produced by beta-amyloid peptide fragment 31-35 on long-term potentiation in rat hippocampus is N-methyl-D-aspartate receptor-independent: it's offset by (-)huperzine A.

Extracellular recordings of field potential from CA1 region of rat hippocampal slices were used to observe the effects of a shorter synthetic fragment of beta-amyloid peptide (A beta31-35) on the induction of long-term potentiation (LTP) and the action of (-)huperzine A, a potent acetylcholinesterase (AChE) inhibitor on these processes was also observed. The results showed that: (1) 0.1 microM A beta31-35 suppressed the induction of LTP in a similar mode as the longer fragment A beta25-35, did, while they did not change the amplitude of the baseline population spike (PS); (2) when PSs were recorded separately in Mg2+-free medium, which unveils the N-methyl-D-aspartate (NMDA)-mediated responses, both A beta31-35 and A beta25-35 showed little effect on the components of multiple PSs; (3) two concentrations of 0.1 microM or 1.0 microM (-)huperzine A showed no effects on the PS amplitude while the latter could enhance the LTP and (4) co-administration of (-)huperzine A with 0.1 microM concentration could block most of the suppressive action induced by A beta31-35 or A beta25-35 upon the LTP. The results suggest that the shorter fragment A beta31-35, is long enough to suppress the induction of LTP and these two fragments might suppress the induction of LTP through a NMDA receptor-independent pathway that involves cholinergic terminals in hippocampus.

Alkaloids↗
PubMed1999

Purinoceptor-coupled Cl- channels in mouse heart: a novel, alternative pathway for CFTR regulation.

1. P2-purinoceptors couple extracellular ATP to the activation of a Cl- current (ICl,ATP) in heart. We studied the molecular mechanism and intracellular signalling pathways of ICl,ATP activation in mouse heart. 2. Extracellular adenosine-5'-O-(3-thiotriphosphate) (ATPgammaS; 100 microM) activated ICl,ATP in both atrial and ventricular myocytes. A specific PKC inhibitor, bisindolylmaleimide blocked the effect of ATPgammaS while a PKC activator, phorbol 12, 13-dibutyrate (PDBu) activated a current with identical properties to ICl,ATP. Maximal activation of ICl,ATP by ATPgammaS or PDBu occluded further modulation by the other agonist, suggesting that they may activate the same population of Cl- channels. 3. Isoprenaline increased ICl,ATP pre-activated by ATPgammaS or PDBu, while isoprenaline or forskolin alone failed to activate any Cl- current in these myocytes. Adenosine 3',5'-cyclic monophosphothionate, a PKA inhibitor, prevented ATPgammaS or PDBu activation of ICl,ATP. Thus, ICl,ATP is regulated by dual intracellular phosphorylation pathways involving both PKA and PKC in a synergistic manner similar to cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels. 4. Glibenclamide (50 microM) significantly blocked ICl,ATP activated by ATPgammaS or by the CFTR channel activator, levamisole. 5. The slope conductance of the unitary ICl,ATP in cell-attached patches was 11.8 +/- 0.3 pS, resembling the known properties of CFTR Cl- channels in cardiac myocytes. 6. The reverse transcription polymerase chain reaction and Northern blot analysis revealed CFTR mRNA expression in mouse heart. 7. We conclude that ICl,ATP in mouse heart is due to activation of CFTR Cl- channels through a novel intracellular signalling pathway involving purinergic activation of PKC and PKA.

Adenosine Triphosphate↗
PubMed1999

Use of molecularly imprinted polymers in a biotransformation process.

Molecularly imprinted polymers are highly stable and can be sterilised, making them ideal for use in biotransformation process. In this communication, we describe a novel application of molecularly imprinted polymers in an enzymatic reaction. The enzymatic condensation of Z-L-aspartic acid with L-phenylalanine methyl ester to give Z-L-Asp-L-Phe-OMe (Z-aspartame) was chosen as a model system to evaluate the applicability of using molecularly imprinted polymers to facilitate product formation. When the product-imprinted polymer is present, a considerable increase (40%) in product yield is obtained. Besides their use to enhance product yields, as demonstrated here, we suggest that imprinted polymers may also find use in the continuous removal of toxic compounds during biochemical reactions.

Aspartame↗
PubMed1999

Frequency of the fragile X syndrome in Chinese mentally retarded populations is similar to that in Caucasians.

Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. We report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals. We found that 2.8% of the Chinese MR population screened by DNA analysis had the fragile X full mutation. Our screening indicated that the fragile X syndrome prevalence was very close to that of Caucasian subjects. In addition, we found that 62.5% of fragile X chromosomes had a single haplotype for DXS548-FRAXAC1 (21-18 repeats) which was present in only 9.7% of controls. This unique distribution of microsatellite markers flanking the FMR1 CGG repeats suggests that the fragile X syndrome in Chinese populations, as in the Caucasian, may also be derived from founder chromosomes.

Alleles↗
PubMed1999

Functional expression, quantification and cellular localization of the Hxt2 hexose transporter of Saccharomyces cerevisiae tagged with the green fluorescent protein.

The Hxt2 glucose transport protein of Saccharomyces cerevisiae was genetically fused at its C-terminus with the green fluorescent protein (GFP). The Hxt2-GFP fusion protein is a functional hexose transporter: it restored growth on glucose to a strain bearing null mutations in the hexose transporter genes GAL2 and HXT1 to HXT7. Furthermore, its glucose transport activity in this null strain was not markedly different from that of the wild-type Hxt2 protein. We calculated from the fluorescence level and transport kinetics that induced cells had 1.4x10(5) Hxt2-GFP molecules per cell, and that the catalytic-centre activity of the Hxt2-GFP molecule in vivo is 53 s-1 at 30 degrees C. Expression of Hxt2-GFP was induced by growth at low concentrations of glucose. Under inducing conditions the Hxt2-GFP fluorescence was localized to the plasma membrane. In a strain impaired in the fusion of secretory vesicles with the plasma membrane, the fluorescence accumulated in the cytoplasm. When induced cells were treated with high concentrations of glucose, the fluorescence was redistributed to the vacuole within 4 h. When endocytosis was genetically blocked, the fluorescence remained in the plasma membrane after treatment with high concentrations of glucose.

Base Sequence↗
PubMed1999

5-HTTLPR variants not associated with autistic spectrum disorders.

To determine whether there is an association of polymorphic variants of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) and autistic spectrum disorders, we analyzed the 5-HTTLPR genotypes of 72 autistic subjects, 11 fragile X syndrome patients with autistic behavior, 43 normal subjects, and 49 fragile X syndrome non-autistic subjects. The distribution frequency of 5-HTTLPR long allele (L) and the short allele (S) variants showed no differences between subjects. Our findings do not support the hypothesis that polymorphic 5-HTTLPR variants are a susceptibility factor for autistic disorders.

Alleles↗