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Biomedical subjects

Jun Ye

Publications and source records attributed to Jun Ye.

At least 37 records · Page 2Linked to original sources
PubMed2005

Precision spectroscopy and density-dependent frequency shifts in ultracold Sr.

By varying the density of an ultracold 88Sr sample from 10(9) to>10(12) cm(-3), we make the first definitive measurement of the density-related frequency shift and linewidth broadening of the 1S0-3P1 optical clock transition in an alkaline earth system. In addition, we report the most accurate measurement to date of the 88Sr 1S0-3P1 optical clock transition frequency. Including a detailed analysis of systematic errors, the frequency is [434 829 121 312 334+/-20(stat)+/-33(syst)] Hz.

Journal Article↗
PubMed2005

Demonstration of a HeNe/CH4-based optical molecular clock.

We implement a simple optical clock based on the F2(2) [P(7), v3] optical transition in methane. A single femtosecond laser's frequency comb undergoes difference frequency generation to provide an IR comb at 3.39 microm with a null carrier-envelope offset. This IR comb provides a phase-coherent link between the 88-THz optical reference and the rf repetition rate. Comparison of the repetition rate signal with a second femtosecond comb stabilized to molecular iodine shows an instability of 1.2 x 10(-13) at 1 s, limited by microwave detection of the repetition rates. The single-sideband phase noise of the microwave signal, normalized to a carrier frequency of 1 GHz, is below -93 dBc/Hz at 1-Hz offset.

Journal Article↗
PubMed2005

Crystal structure of the Staphylococcus aureus pI258 CadC Cd(II)/Pb(II)/Zn(II)-responsive repressor.

The Staphylococcus aureus plasmid pI258 cadCA operon encodes a P-type ATPase, CadA, that confers resistance to the heavy metals Cd(II), Zn(II), and Pb(II). Expression of this heavy-metal efflux pump is regulated by CadC, a homodimeric repressor that dissociates from the cad operator/promoter upon binding of Cd(II), Pb(II), or Zn(II). CadC is a member of the ArsR/SmtB family of metalloregulatory proteins. Here we report the X-ray crystal structure of CadC at 1.9 angstroms resolution. The dimensions of the protein dimer are approximately 30 angstroms by 40 angstroms by 70 angstroms. Each monomer contains six alpha-helices and a three-stranded beta-sheet. Helices 4 and 5 form a classic helix-turn-helix motif that is the putative DNA binding region. The alpha1 helix of one monomer crosses the dimer to approach the alpha4 helix of the other monomer, consistent with the previous proposal that these two regulatory metal binding sites for the inducer cadmium or lead are each formed by Cys-7 and Cys-11 from the N terminus of one monomer and Cys-58 and Cys-60 of the other monomer. Two nonregulatory metal binding sites containing zinc are formed between the two antiparallel alpha6 helices at the dimerization interface. This is the first reported three-dimensional structure of a member of the ArsR/SmtB family with regulatory metal binding sites at the DNA binding domain and the first structure of a transcription repressor that responds to the heavy metals Cd(II) and Pb(II).

Amino Acid Sequence↗
PubMed2005

[Prenatal diagnosis of glycogen storage disease Ia by screening for hot spot mutations in combination with the 1176 nucleotide polymorphism linkage analysis].

OBJECTIVE: To develop and evaluate a simple, fast and accurate prenatal diagnosis method for glycogen storage disease Ia (GSD Ia) in Chinese. METHODS: This study involved 3 unrelated families. Genomic DNA samples were extracted from the blood of three GSD Ia patients and their parents, from the amniocytes of 3 fetuses and the blood of 2 newborns. By the way of restriction enzyme analysis, the screening for 727G-->T and R83H mutations of glucose-6-phosphatase gene was carried out in conjunction with 1176 nucleotide polymorphism linkage analysis so as to make the gene and prenatal diagnosis of 3 GSD Ia families. Direct DNA sequencing of the corresponding PCR products was used to confirm the unveiled mutations and 1176 nucleotide polymorphism. RESULTS: Three probands were homozygotes for the 727G-->T mutation and their parents were heterozygotes for this mutation. The fetuses of family 1 and 3 were heterozygotes for the 727G-->T mutation, whereas the fetus of family 2 did not carry this mutation. The 1176 nucleotide polymorphisms of 3 fetuses were different from those of the corresponding probands. The prenatal diagnoses of family 1 and 2 were confirmed by the postnatal biochemical and molecular studies. CONCLUSION: These findings suggest that the screening for 727G-->T and R83H mutations in conjunction with the 1176 polymorphism linkage analysis be a simple, fast and accurate method for gene and prenatal diagnosis of GSD Ia in Chinese.

Adult↗
PubMed2005

[Application of tandem mass spectrometry in diagnosis of organic acidemias].

OBJECTIVE: The diagnosis of organic acidemia is very difficult and needs special test methods. Recently the tandem mass spectrometry has been used in screening for and diagnosis of this inborn error of metabolism. The aim of the present study was to utilize a dry blood filter paper method for acylcarnitines profiles test using tandem mass spectrometry in diagnosis of organic acidemias in high risk children. METHOD: One thousand patients (642 were males and 358 females) with high risk of inborn error of metabolism were studied, the median of their age was 2 years. The blood specimens were collected on filter paper, punched and extracted into methanol solution with stable isotope labeled internal standards of acylcarnitine, then derivatized with butanolic-HCI. After preparation, the samples were analyzed by tandem mass spectrometry. The volume of the acylcarnitines was calculated with special software. RESULTS: Forty patients (4.0%) were diagnosed as organic acidemias among the 1000 patients, including 20 methylmalonic acidemia, 6 propionic acidemia, 3 isovaleric acidemia, 3 glutaric acidemia type I, 3 glutaric acidemia type II, 2 biotinidas deficiency, 1 3-methylcrotonyl-CoA carboxylase deficiency, 1 3-hydroxy-3-methylglutaryl-CoA lyase deficiency, and 1 beta-keto thiolase deficiency. The common clinical symptoms and signs of these patients were motor and mental developmental retardation, spasm, lethargy, coma, hypotonia, vomiting, and feeding difficulty. Routine laboratory tests suggested metabolic acidosis, hyperammonemia, hyperlactacidemia, hypoglycemia, anemia, and abnormal liver function. CONCLUSION: A part of organic acidemias can be rapidly diagnosed by tandem mass spectrometry through acylcarnitine profiles analysis in dry blood filter paper. Combination of tandem mass spectrometry with urine gas chromatography mass spectrometry would improve more accurate diagnosis of organic acidemias.

Adolescent↗
PubMed2005

[Screening and diagnosis of tetrahydrobiopterin responsive phenylalanine hydroxylase deficiency with tetrahydrobiopterin loading test].

OBJECTIVE: Tetrahydrobiopterin (BH(4)) responsive phenylalanine hydroxylase (PAH) deficiency is one of the forms of phenylketonuria (PKU). The aim of this study was to screen and diagnose BH(4) responsive PAH deficiency, to further understand its clinical characteristics, and to provide evidence for applying BH(4) drug therapy. METHODS: BH(4) 20 mg/kg loading test was performed in 73 patients with hyperphenylalaninemia (HPA) (47 males and 26 females), the mean age was 1.93 months. Combined phenylalanine (100 mg/kg) and BH(4) loading test was performed if patients had a basic blood phenylalanine concentration less than 600 micromol/L. The urine pterin profile analysis and the dihydropteridine reductase (DHPR) activity in dry blood filter spot were analyzed simultaneously. The patients with BH(4) responsive PAH deficiency were treated with BH(4) tablets (10 - 20 mg/kg x d) under normal diet for 6 to 7 days. Their blood phenylalanine concentration was checked. RESULTS: (1) The characteristic curve of phenylalanine level was observed in 73 patients after BH(4) loading test. Twenty-two patients were diagnosed as classic phenylketonuria (PKU), 39 were moderate PKU and 12 were BH(4) deficiency. (2) Twenty-two (56.4%) of 39 moderate PKU patients were found to be responsive to BH(4) and the blood phenylalanine was decreased by at least 30%. (3) Six patients with BH(4) responsive PAH deficiency were treated with BH(4) for 6 to 7 days, 4 patients had a normal phenylalanine concentration after 10 mg/kg BH(4) supplement, while other 2 patients needed a treatment of BH(4) at 20 mg/kg. CONCLUSION: Some patients with moderate PKU caused by phenylalanine hydroxylase deficiency were responsive to BH(4). Their blood phenylalanine significantly decreased after oral BH(4) loading. The BH(4) loading test is an effective diagnostic method to detect BH(4) sensitivity in PKU patients. BH(4) responsive PAH deficiency patient could be treated with BH(4) to replace low-phenylalanine diet treatment totally or partially, which may provide an optional treatment for the disease and improve the quality of life of the patients.

Biopterins↗
PubMed2005

[Tetrahydrobiopterin loading test in differential diagnosis among hyperphenylalaninemia patients].

OBJECTIVE: To perform tetrahydrobiopterin (BH(4)) loading test and to further understand its usefulness in differential diagnosis among hyperphenylalaninemia(HPA) patients. METHODS: BH(4) loading test was carried out in 73 HPA patients, including the positive cases unveiled by neonatal screening and the clinically suspected cases. These patients, 47 males and 26 females, were at a mean age of 1.93 months. BH(4) (20 mg/kg) loading test was performed in all patients, and a combined phenylalanine (Phe)(100 mg/kg) and BH(4) loading test was performed among the patient who had a basic blood Phe concentration less than 600 micro mol/L. The urine pterine profile analysis and the dihydropteridine reductase activity in dry blood filter spot were tested simultaneously. RESULTS: During BH(4) loading test or combined Phe and BH(4) loading test, the patients with classic phenylketonuria showed no response to BH(4), the patients with moderate HPA caused by Phe hydroxylase deficiency decreased 32.8% of blood Phe level and the patients with BH(4) deficiency showed a prompt reduction in blood Phe level and it decreased to normal level at 4 h and lasted until 24 h. Twenty-two cases were diagnosed as classic phenylketonuria, 39 were moderate phenylketonuria and 12 were BH(4) deficiency. CONCLUSION: Hyperphenylalaninemia may be caused by deficiency of Phe hydroxylase or by deficiency of co-factor BH(4). Early diagnosis is important. BH(4) loading test is a safe and fast test in vivo. It is sensitive, easy-to-do, and is highly useful in differential diagnosis for suspected cases of HPA.

Biopterins↗
PubMed2004

High-repetition-rate coherent femtosecond pulse amplification with an external passive optical cavity.

We demonstrate a general technique for enhancement of femtosecond pulses from a pulse train through their coherent buildup inside a high-finesse cavity. Periodic extraction of the intracavity pulse by means of a fast switch provides a net energy gain of 42 to >70 times for 38-58-fs pulse durations. Starting with an actively stabilized but otherwise standard mode-locked laser system, we demonstrate pulses of >200-nJ energy.

Journal Article↗
PubMed2004

United time-frequency spectroscopy for dynamics and global structure.

Ultrashort laser pulses have thus far been used in two distinct modes. In the time domain, the pulses have allowed probing and manipulation of dynamics on a subpicosecond time scale. More recently, phase stabilization has produced optical frequency combs with absolute frequency reference across a broad bandwidth. Here we combine these two applications in a spectroscopic study of rubidium atoms. A wide-bandwidth, phase-stabilized femtosecond laser is used to monitor the real-time dynamic evolution of population transfer. Coherent pulse accumulation and quantum interference effects are observed and well modeled by theory. At the same time, the narrow linewidth of individual comb lines permits a precise and efficient determination of the global energy-level structure, providing a direct connection among the optical, terahertz, and radio-frequency domains. The mechanical action of the optical frequency comb on the atomic sample is explored and controlled, leading to precision spectroscopy with an appreciable reduction in systematic errors.

Journal Article↗
PubMed2004

Capsule oxymatrine in treatment of hepatic fibrosis due to chronic viral hepatitis: a randomized, double blind, placebo-controlled, multicenter clinical study.

AIM: To evaluate the efficacy and safety of oxymatrine capsule in treatment of hepatic fibrosis in patients with chronic viral hepatitis. METHODS: It was a randomized, double blind, placebo-controlled, multicenter clinical study. One hundred and forty-four patients were divided into oxymatrine capsule group(group A) and placebo group (group B). The course was 52 wk. Patients were visited once every 12 wk and the last visit was at 12 wk after cessation of the treatment. All patients had liver biopsy before treatment. part of them had a second biopsy at the end of therapy. Clinical symptoms, liver function test, serum markers of hepatic fibrosis were tested. Ultrasound evaluation was performed before, during and at the end of therapy. RESULTS: One hundred and forty-four patients enrolled in the study. Of them 132 patients completed the study according to the protocol,49 patients had liver biopsy twice (25 patients in group A and 24 in group B). At the end of therapy, significant improvements in hepatic fibrosis and inflammatory activity based on Semi-quantitative scoring system (SSS) were achieved in group A. The total effective rate of the treatment was 48.00%, much higher than that of 4.17% in group B (P<0.05). Significant improvement in serum markers of hepatic fibrosis such as hyaluronic acid (HA) and type III procollagenic peptide (P III P) in group A was seen (P<0.05). The total effective rate of serum markers at the end of therapy in group A was 68.19%, much higher than that of 34.85% in group B (P<0.05). The total effective rate of noninvasive markers at the end of therapy in group A was 66.67%, much higher than that of 30.30% in group B (P<0.05). The rate of adverse events was similar in two groups. CONCLUSION: Oxymatrine capsule is effective and safe in treatment of hepatic fibrosis due to chronic viral hepatitis.

Administration, Oral↗
PubMed2004

Narrow line cooling: finite photon recoil dynamics.

We present an extensive study of the unique thermal and mechanical dynamics for narrow-line cooling on the 1S0-3P1 88Sr transition. For negative detuning, trap dynamics reveal a transition from the semiclassical regime to the photon-recoil-dominated quantum regime, yielding an absolute minima in the equilibrium temperature below the single-photon-recoil limit. For positive detuning, the cloud divides into discrete momentum packets whose alignment mimics lattice points on a face-centered-cubic crystal. This novel behavior arises from velocity selection and "positive feedback" acceleration due to a finite number of photon recoils. Cooling is also achieved with blue-detuned light around a velocity where gravity balances the radiative force.

Journal Article↗
PubMed2004

Precise frequency transfer through a fiber network by use of 1.5-microm mode-locked sources.

We report the precise transfer of radio-frequency signals by use of the pulse repetition frequency of mode-locked laser sources at 1.5 microm transmitting through a fiber network. The passive transfer instability through a 6.9-km fiber is below 3 x 10(-14) at 1 s, which is comparable with the optical carrier-frequency transfer of a narrow-linewidth cw laser. The instability of the measurement system is below 7 x 10(-15) at 1 s. It is noted that the pulsed mode of operation offers almost an order-of-magnitude improvement in stability at 1 s over that with a sinusoidal amplitude modulation on an optical carrier.

Journal Article↗
PubMed2004

Absolute measurement of a long, arbitrary distance to less than an optical fringe.

A scheme is proposed for high-precision, absolute length measurement for an arbitrary optical distance of a few meters to beyond 10(6) m. The approach utilizes a phase-stabilized femtosecond laser to provide both incoherent, time-of-flight information and coherent, fringe-resolved interferometry. Such a combined measurement capability allows an optical wavelength resolution to be achieved for absolute length measurement over a large dynamic range.

Journal Article↗
PubMed2004

[Prospect of the foveola formation in the bovine trabecular bone under fatigue process].

This study aims at the mechanism of foveola formation in bovine trabecular bone under fatigue process and its relation with biomechanical pathogenesis of senile osteoporosis. The scanning electron microscope equipped with fatigue stage was used to observe fatigue micro injury accumulation of cancellous bone. The massive foveola formation in the laminal bone of vertical trabeculae was found in the tensile fatigue test. There existed the collagen avulsion in the foveola. The massive foveola formation was also observed in the lamina bone of the horizontal trabeculae in the compressive fatigue test. The bone collagen fibers were protracted, debound with hydroxyapatite crystal, and then avulsed under tensile and bending stresses. Finally the retraction of the avulsed collagen fibers brought on the massive formation of foveolae in lamina bone. The mechanical capacity of bone also declined greatly. We infer that the direct mineralization of avulsed collagen and foveola in lamina bone would be one of the main processes of self repair in vivo, which brings on the increase in fragility and stiffness of trabeculae of senile osteoporotic bone along with the agelong accumulation of collagen fatigue injury and foveola formation in the lamina bone.

Animals↗
PubMed2004

Clinical and genetic features of International Collaborative Group-hereditary nonpolyposis colorectal cancer families and suspected hereditary nonpolyposis colorectal cancer families.

BACKGROUND: Hereditary nonpolyposis colorectal cancer (HNPPC) is one of the most common genetic syndrome related with mutation of human mismatch repair genes. This study was to evaluate the clinical significance of suspected hereditary nonpolyposis colorectal cancer (sHNPCC) criteria I and the clinical and genetic features of International Collaborative Group-HNPCC (ICG-HNPCC) and sHNPCC families. METHODS: Twenty-nine ICG-HNPCC families fulfilling the Amsterdam criteria and 34 sHNPCC families fulfilling the sHNPCC criteria I were collected. PCR-SSCP and DNA sequencing analysis were employed to screen the germline mutations of the hMLH1 and hMSH2 genes in these families. RESULTS: The ICG group had more colorectal cancer (CRC) patients per family than did the suspected group (P < 0.05). No statistical difference was observed in Lynch classification and familial tumor spectrum. In both groups of families, colorectal cancer was the most frequent malignancy, and carcinomas of the stomach, pancreas and uterus were the three most common extracolonic malignancies. Mutation screening showed that ICG-HNPCC and sHNPCC families had a similar mutation rate (31.0% vs 29.4%, P > 0.05), mutation type, and mutation distribution. Comparison of the families with and without mutation showed no significant difference in CRC patients per family, Lynch classification, and tumor spectrum. CONCLUSIONS: ICG-HNPCC and sHNPCC families that have similar clinical manifestations and genetic basis indicate a similar nature for cancer development. The application of sHNPCC criteria I will facilitate clinical diagnosis and treatment of small families.

Adaptor Proteins, Signal Transducing↗
PubMed2004

[Structural characterization of 5' flanking regulatory region of DNA repair gene Rad51].

OBJECTIVE: To clarify the regulatory elements of Rad51 gene in its 5'flanking region. METHODS: Various constructs were obtained by cloning different DNA fragments into pGL3 reporter vector. These constructs were then introduced into osteosarcoma cell line U2-OS by calcium phosphate method for transient expression of reporter gene, and luciferase activities were measured by luciferase assay. RESULTS: Cells transfected with pGL3 constructs containing fragment -964 to +1430 and -733 to +1430 showed high luciferase activities. Obvious elevation of luciferase activities was also observed in cells transfected with pGL3 constructs containing four shorter derivative fragments -964 to -412, -746 to -412, -651 to -412 and -536 to -412. The highest luciferase activities were measured in transfected cells with plasmids containing fragment -964 to -412, and the lowest were in transfected cells with plasmids containing fragment -536 to -412. Luciferase activities in transfected cells with plasmids containing fragment -651 to -412 were higher than that in transfected cells with plasmids containing fragment -746 to -412. CONCLUSION: It is believable that the basic transcription-promoting element (promoter) for Rad51 gene resides between -536 to -412, and two transcription-enhancing elements (enhancer) or binding sites of positive transcription factors reside between -651 to -536 and -964 to -746, whereas one transcription-inhibiting element (silencer) or binding site of negative transcription factor may reside between -746 to -651.

5' Flanking Region↗
PubMed2004

[Study on mutations of exon 12 of the PAH gene in 127 phenylketonuria patients].

OBJECTIVE: To obtain the mutation spectrum of exon 12 of the phenylalanine hydroxylase(PAH) gene. METHODS: The samples from 127 patients with phenylketonuria(PKU) were studied by polymerase chain reaction(PCR)-single strand conformation polymorphism(SSCP) PCR-denaturing gradient gel electrophoresis(DGGE) and direct DNA sequencing. RESULTS: Four heterozygous mutations including R413P S411X R408W R408Q in 10 of 127 patients were identified by DNA sequencing. The frequencies of R413P S411X R408W R408Q mutation were 2.76%, 0.39%, 0.39% and 0.39%, respectively. The S411X mutation in Chinese was first reported. Only 2 cases with R413P mutation were detected by SSCP. DGGE analysis showed that 10 cases displayed 3 kinds of abnormal electrophoretic bands. There were no obvious differences in the frequency of R413P mutation between northern and southern Chinese with PKU, and between classical PKU and hyperphenylalaninemia. CONCLUSION: DGGE is more sensitive than SSCP in screening the mutations of exon 12 of the PAH gene. DGGE combined with DNA sequencing can be used to define all the mutations of exon 12 of the PAH gene. These results indicate the similarity in the frequency of R413P mutation between northern and southern patients.

Electrophoresis, Polyacrylamide Gel↗