Search PubMed⌕ Search

Biomedical subjects

L Jin

Publications and source records attributed to L Jin.

At least 19 recordsLinked to original sources
PubMed2006

Variation in proton affinity of the guanidino group between free and blocked arginine.

In this paper, the analog of arginine residues in peptides was synthesized and characterized by ESI-MS/MS (electrospray ionization with tandem mass spectrometry), (31)P NMR, (1)H NMR, IR and high-resolution mass spectrometry. When the Todd reaction activity of the guanidino group in free arginine and the arginine peptide analog were compared, it was found that the proton affinity of the guanidino group was decreased when both the N- and the C-terminal were blocked. As a result, the guanidino group of arginine residues in peptides could be phosphorylated under the Todd reaction condition, but not the free arginine. This result was further proved by the theoretical calculation of their proton affinity.

Arginine↗
PubMed2006

Acrylamide, an in vivo thyroid carcinogenic agent, induces DNA damage in rat thyroid cell lines and primary cultures.

Chronic treatment of rats with acrylamide induces various tumors among which thyroid tumors are the most frequent. The aim of the present study was to develop an in vitro model of acrylamide action on thyroid cells to allow the investigation of the mechanism of this tumorigenic action. The first part of the study considered as targets, characteristics of thyroid metabolism, which could explain the thyroid specificity of acrylamide action: the cAMP mitogenic effect and the important H2O2 generation by thyroid cells. However, acrylamide did not modulate H2O2 or cAMP generation in the thyroid cell models studied. No effect on thyroid cell proliferation was observed in the rat thyroid cell line FRTL5. On the other hand, as shown by the comet assay, acrylamide induced DNA damage, as the positive control H2O2 in the PC Cl3 and FRTL5 rat thyroid cell lines, as well as in thyroid cell primary cultures. The absence of effect of acrylamide on H2AX histone phosphorylation suggests that this effect does not reflect the induction of DNA double strand breaks. DNA damage leads to the generation of mutations. It is proposed that such mutations could play a role in the carcinogenic effect of acrylamide. The mechanism of this effect can now be studied in this in vitro model.

Acrylamide↗
PubMed2006

Measles viral load may reflect SSPE disease progression.

Subacute sclerosing panencephalitis (SSPE) is a rare, slowly progressive neurological disorder caused by the persistent infection with measles virus (MV). Despite much research into SSPE, its pathology remains obscure. We examined autopsy tissues of eight SSPE patients by real time quantitative PCR, immunohistochemistry and immunoblotting to determine viral load. MV N, M and H gene RNA could be detected in the central nervous system (CNS) of all patients and in two non-CNS tissues of one patient. The viral burden between patients differed up to four-fold by quantitative PCR and corresponded with detection of MV protein. The level of both viral RNA and antigen in the brain may correlate with disease progression.

Adolescent↗
PubMed2006

Suppression of tumor growth using a recombinant adenoviral vector carrying the dominant-negative mutant gene Survivin-D53A in a nude mice model.

Survivin (SVV), an inhibitor of apoptosis protein, is found to be upregulated in many cancers. We previously demonstrated that a dominant-negative mutant SVV-D53A was able to induce apoptosis in a p53-independent manner. Here, we report the construction and characterization of a recombinant replication-deficient adenoviral vector encoding a human SVV-D53A gene for its effectiveness against tumor growth both in vitro and in vivo. Transfection of liver tumor cells QGY-7703 with Ad-SVV-D53A results in significant apoptosis as measured by an increase in sub-G1 DNA content, procaspase-9 activation and further downstream PARP-1 cleavage. Furthermore, animal studies using QGY-7703 liver carcinoma xenografts in nude mice revealed that treatment of QGY-7703 cells with dominant-negative SVV-D53A, but not with wild-type SVV-adenovirus, prevents tumor outgrowth, inhibits growth of established tumors and results in a notably improved survival advantages in xenograft studies. Both the transferase-mediated dUTP nick-end labeling assay and immunostaining experiment demonstrated that tumor growth inhibition is associated with apoptosis induced by SVV-D53A expression. Taken together, these data suggest that recombinant adenovirus Ad-SVV-D53A carrying a Survivin dominant-negative gene SVV-D53A promotes apoptosis-mediated tumor suppression and could potentially be a promising candidate for cancer therapies.

Adenoviridae↗
PubMed2006

Signatures of differentially regulated interferon gene expression and vasculotrophism in the peripheral blood cells of systemic sclerosis patients.

OBJECTIVE: To obtain a global view of the immunological alterations occurring in early systemic sclerosis (SSc) by transcriptional profiling of peripheral blood cells (PBCs). METHODS: Oligonucleotide microarrays were used to compare PBC gene expression profiles in 18 SSc cases (<2 yr duration) and 18 controls matched for race, gender and ethnicity. SSc cases had no prior or current exposure to cytotoxic drugs. PAXgene tubes were used to stabilize RNA during phlebotomy. Changes in gene expression were independently validated by real-time polymerase chain reaction. RESULTS: SSc PBCs demonstrated differential expression of 18 interferon-inducible genes. Six of these genes were identical to the interferon signature genes in lupus peripheral blood mononuclear cells. Notably, SSc PBCs also had increased expression of allograft inflammatory factor (AIF1) and several selectins and integrins involved in cellular adhesion to the endothelium. Global analysis of 284 known biological pathways revealed that 13 were differentially regulated in SSc PBCs, including two pathways (IL2RB and GATA3) that lead to T(H)2 polarization. CONCLUSIONS: Transcriptional profiling reliably discriminates between PBCs from SSc and normal donors despite the fact that they represent a heterogeneous cell population. Multiple biological pathways were differentially regulated in SSc PBCs, but a common thread across these pathways was alterations in protein tyrosine kinase 2beta and mitogen-activated protein kinase signalling. Although the SSc PBC gene expression profile demonstrated some parallels with the lupus interferon gene signature, there was also increased expression of transcripts encoding proteins that target PBCs to the endothelium, which might be relevant to the vasculopathy of SSc.

Adult↗
PubMed2006

LPP expression during in vitro smooth muscle differentiation and stent-induced vascular injury.

Lipoma preferred partner (LPP) has been identified as a protein highly expressed in smooth muscle (SM) tissues. The aim of the present study was to determine mechanisms that regulate LPP expression in an in vitro model of SM cell (SMC) differentiation and in stent-induced pig coronary vessel injury. All trans-retinoic acid treatment of A404 cells induced a strong increase in LPP, as well as SM alpha-actin, SM myosin heavy chain, and smoothelin mRNA levels, in a Rho kinase (ROK)-dependent manner. Adenovirus mediated overexpression of myocardin in A404 cells significantly increased LPP mRNA expression. Interestingly, inactivation of RhoA with C3-exoenzyme or treatment with ROK inhibitors strongly inhibited myocardin mRNA expression in retinoic acid-treated A404 cells or human iliac vein SMCs. LPP silencing with short interfering RNA significantly decreased SMC migration. LPP expression was also markedly decreased in focal adhesion kinase (FAK)-null cells known to have impaired migration but rescued with inducible expression of FAK. LPP expression in FAK-null fibroblasts enhanced cell spreading. In stented pig coronary vessels, LPP was expressed in the neointima of cells lacking smoothelin and showed expression patterns identical to those of SM alpha-actin. In conclusion, LPP appears to be a myocardin-, RhoA/ROK-dependent SMC differentiation marker that plays a role in regulating SMC migration.

Animals↗
PubMed2006

Serological and molecular epidemiology of measles virus outbreaks reported in Ethiopia during 2000-2004.

Twenty-eight outbreaks in six regions and two major cities in Ethiopia from 2000 to 2004 were investigated, with the collection of 207 venous blood and/or oral fluid samples. Measles diagnosis was confirmed by detection of measles-specific IgM and/or detection of measles virus by polymerase chain reaction (PCR). Of 176 suspected cases tested for specific measles IgM, 142 (81%) were IgM positive. Suspected cases in vaccinated children were much less likely to be laboratory confirmed than in unvaccinated children (42% vs. 83%, P < 0.0001). Of 197 samples analyzed by RT-PCR measles virus genome was detected in 84 (43%). A total of 58 wild-type measles viruses were characterized by nucleic acid sequence analysis of the nucleoprotein (N) and hemagglutinin (H) genes. Two recognized genotypes (D4 and B3) were identified. Each outbreak comprised only a single genotype and outbreaks of each genotype tended to occur in distinct geographical locations. B3 was first observed in 2002, and has now been the cause of three documented outbreaks near to the border of Sudan. D4 genotype was previously observed in an outbreak in 1999 and occurs in more diverse locations throughout the country. These data yield insights into geographical and age-related sources of continued transmission. Refinement of measles control measures might include targeting older age groups (5-14 years) and strengthening routine immunization particularly where importation of cases is a concern.

Adolescent↗
PubMed2006

Transcriptional control in the mammalian liver: liver development, perinatal repression, and zonal gene regulation.

Liver function is crucial for maintaining metabolic homeostasis in mammals. Numerous genes must be properly regulated for the liver to develop and perform a variety of activities. Several recent gene-knockout studies in mice have clarified the roles of GATA6, HNF4alpha, and Foxa1/Foxa2 in early stages of liver formation. After the liver forms, transcriptional changes continue to occur; during the perinatal period, certain genes such as alpha-fetoprotein and H19 are silenced, others are activated, and position-dependent (or zonal) regulation is established. Zhx2 was recently identified as one factor involved in postnatal repression of alpha-fetoprotein and other genes. Furthermore, several studies indicate that negative regulation is involved in the zonal control of glutamine synthetase. Finally, exciting new evidence indicates that signaling through the Wnt/beta-catenin pathway is also involved in zonal regulation in the adult liver.

ADP-Ribosylation Factor 1↗
PubMed2006

Value of B-type natriuretic peptide in diagnosing left ventricular dysfunction in dialysis-dependent patients.

BACKGROUND: B-type natriuretic peptide (BNP) is elevated in patients with end-stage renal failure. The reported accuracy of BNP in diagnosing left ventricular dysfunction in these patients has been inconsistent. AIM: To investigate the diagnostic values of BNP for left ventricular dysfunction in patients undergoing haemodialysis for chronic renal failure. METHODS: We measured plasma BNP before and at 10 min and 3, 6 and 24 h after haemodialysis in 56 patients. RESULTS: The average plasma BNP before haemodialysis was 284 +/- 369 pg/mL, which was higher than that of healthy subjects (37 +/- 37 pg/mL; n = 32, P < 0.01). The average plasma BNP in patients with left ventricular dysfunction (n = 21) was substantially higher than that in those with normal ventricular function before and at 10 min and 3, 6 and 24 h after haemodialysis (P < 0.001). The area under the receiver operating characteristic curves was greater than 0.895 before and at the four time points after haemodialysis (P < 0.01). Using 152 pg/mL as a cut-off value, predialysis BNP has 81% sensitivity and 83% specificity in diagnosing left ventricular dysfunction in these patients. CONCLUSION: We concluded that plasma BNP offers a good sensitivity and specificity in diagnosing left ventricular dysfunction in patients with dialysis-dependent renal failure.

Adolescent↗
PubMed2006

A frequent partial AZFc deletion does not render an increased risk of spermatogenic impairment in East Asians.

The gene families in the AZFc region of the Y chromosome have been shown to be functionally important in human spermatogenesis. The gr/gr deletion, a partial AZFc deletion that reduces the copy numbers of all the AZFc gene families, was identified as a significant risk factor for spermatogenic impairment in Dutch, Spanish and Italians. However, the presence of this deletion in healthy French and Germans questioned its importance in male infertility. In this study, we have shown that the gr/gr deletion does not render an increased risk in Han Chinese. In fact, the gr/gr deletion is frequent (about 8%) in our survey of 886 East Asians from 8 ethnic groups. Furthermore, the DAZ1/DAZ2 deletion has been detected as the primary subtype of the gr/gr deletion in East Asians, though this doublet has been considered as crucial for normal spermatogenesis in Europeans. The different spermatogenic effects of various types of the partial AZFc deletion suggest that the functional difference between AZFc gene copies is a likely cause of inconsistent associations of the gr/gr deletion with spermatogenic impairment across populations.

Base Sequence↗
PubMed2006

Measles-associated encephalopathy in children with renal transplants.

Two children, boys of 8 and 13 years, presented with measles-associated encephalopathy several years after kidney transplantation for congenital nephrotic syndrome. In the absence of prior clinical measles, the neurological symptoms initially eluded diagnosis, but retrospective analysis of stored samples facilitated the diagnosis of measles-associated encephalopathy without recourse to biopsy of deep cerebral lesions. Each had received a single dose of measles mumps and rubella vaccine before 12 months of age. Prior vaccination, reduction of immunosuppression and treatment with intravenous immunoglobulin and ribavirin may have contributed to their survival. Persistent measles virus RNA shedding, present in one child, was not controlled by treatment with i.v. ribavirin. Two years later, both patients continue to have functioning allografts with only minimal immunosuppression. These cases illustrate the difficulty in diagnosing measles-associated encephalopathy in the immunocompromised host, even in the era of molecular diagnostics, and highlight the renewed threat of neurological disease in communities with incomplete herd immunity.

Adolescent↗
PubMed2006

Testosterone induces apoptosis via Fas/FasL-dependent pathway in bone marrow-derived macrophages.

The detailed mechanisms behind the apoptosis of macrophages induced by testosterone are not clear. In the present study, we tried to delineate the effect of testosterone on the apoptosis of bone marrow-derived macrophages (BMMs) and the function of Fas/FasL (Fas ligand) pathway in this course. BMMs were stimulated with testosterone in the presence of macrophage colony stimulating factor (M-CSF) or without. Flow cytometry was used to quantify the apoptosis of BMMs. Real-time RT-PCR and Western blot were performed to analyze the expression of caspase-8, caspase-3, and poly(ADP-ribose) polymerase (PARP) during the Fas/FasL pathway. Our data showed that testosterone could induce the apoptosis of BMMs, similar to removing growth factor M-CSF from the culture medium. They were both associated with the enhanced expression of caspase-8, caspase-3, and PARP. And the phosphorothioate antisense oligodeoxynucleotides to fas-associated death domain protein (FADD) could block the expression of FADD, which is an upstream factor of caspase-8 in the Fas/FasL pathway. It led to the reduced obvious expression of caspase-8 and decreasing apoptosis of BMMs. These results suggest that the Fas/FasL pathway may play an important role in the testosterone-induced apoptosis of macrophages.

Animals↗
PubMed2006

Increased reactive oxygen species contributes to kidney injury in mineralocorticoid hypertensive rats.

Hypertension is associated with increased reactive oxygen species (ROS). Renal ROS production and their effects on renal function have never been investigated in mineralocorticoid hypertensive rats. In this study we hypothesized that increased ROS production in kidneys from deoxycorticosterone (DOCA)-salt rats contributes to adverse renal morphological changes and impaired renal function in DOCA-salt hypertensive rats. We also determined whether ROS-induced renal injury was dependent on blood pressure. DOCA-salt hypertensive rats exhibited a marked increase in blood pressure, renal ROS production, glomerular and tubular lesions, and microalbuminuria compared to sham rats. Treatment of DOCA-salt hypertensive rats with apocynin for 28 days resulted in attenuation of systolic blood pressure and improvement of renal morphology. Renal superoxide level in DOCA-salt rats was 215% of sham-operated rats and it was significantly decreased to 140% with apocynin treatment. Urinary protein level was decreased from 27 +/- 3 mg/day in DOCA-salt hypertensive rats to 9 +/- 2 mg/day. 28 days of Vitamin E treatment also reduced renal injury in regard to urinary protein level and renal morphology but had no effect on blood pressure in DOCA-salt rats. Increased urinary 8-isoprostane, a marker for oxidative stress, in DOCA-salt hypertensive rats (55 +/- 8 ng/day) was diminished by vitamin E treatment (24 +/- 6 ng/day). These data suggest that renal injury characteristic of mineralocorticoid hypertension is associated with oxidative stress and is partly independent of blood pressure.

Acetophenones↗
PubMed2005

Improved RT-PCR for diagnosis and epidemiological surveillance of rubella.

A reverse transcription nested polymerase chain reaction (RT-PCR) assay was developed and evaluated for detection of rubella virus (RV) RNA directly from clinical specimens using primers that amplified 592 nucleotides, of a variable region within the E1 gene. RV RNA was detected in pre- and post-natal congenital rubella samples and samples from patients with acute rubella, which suggests that it is a reliable technique for rubella diagnosis and surveillance. The sensitivity of the PCR was found to be equivalent to that of previously published assays, which amplify smaller regions of the E1 gene. This improved RT-PCR is much more specific for detection of the rubella genome compared to our previous PCR, where some primers were complementary to the human genome. The larger size of the PCR amplicon was also useful for molecular genotyping of virus strains.

Base Sequence↗
PubMed2005

Proposal for genetic characterisation of wild-type mumps strains: preliminary standardisation of the nomenclature.

Though mumps virus (MuV) is a monotypic virus, genetic variation between strains has been described. Viruses have been placed into genotypes designated A-L based on the nucleotide sequence of the small hydrophobic (SH) gene, which is the most variable gene in the mumps genome. Molecular characterisation of MuV is an important component of mumps surveillance because it can help identify the transmission pathways of the virus as well as distinguish between wild-type and vaccine strains. Here, we propose a standardized nomenclature and an analysis protocol for the genetic characterisation of mumps strains to facilitate expansion of molecular epidemiological studies. In addition to assigning standard reference strains for the recognized genotypes of MuV, a convention is proposed for naming for strains and criteria to designate a new genotype.

Humans↗
PubMed2005

Wavelength- and time-dependence of potentiometric non-linear optical signals from styryl dyes.

Second harmonic generation (SHG) imaging microscopy is an important emerging technique for biological research, complementing existing one- and two-photon fluorescence (2PF) methods. A non-linear phenomenon employing light from mode-locked Ti:sapphire or fiber-based lasers, SHG results in intrinsic optical sectioning without the need for a confocal aperture. Furthermore, as a second-order process SHG is confined to loci lacking a center of symmetry, a constraint that is readily satisfied by lipid membranes with only one leaflet stained by a dye. Of particular interest is "resonance-enhanced" SHG from styryl dyes in cellular membranes and the possibility that SHG is sensitive to transmembrane potential. We have previously confirmed this, using simultaneous voltage-clamping and non-linear imaging of cells to find that SHG is up to four times more sensitive to potential than fluorescence. In this work, we have extended these results in two directions. First, with a range of wavelengths available from a mode-locked Ti:sapphire laser and a fiber-based laser, we have more fully investigated SHG and 2PF voltage-sensitivity from ANEP and ASTAP chromophores, obtaining SHG sensitivity spectra that are consistent with resonance enhancements. Second, we have modified our system to coordinate the application of voltage-clamp steps with non-linear image acquisition to more precisely characterize the time dependence of SHG and 2PF voltage sensitivity, finding that, at least for some dyes, SHG responds more slowly than fluorescence to changes in transmembrane potential.

Fiber Optic Technology↗
PubMed2005

Persistent shedding of viable SARS-CoV in urine and stool of SARS patients during the convalescent phase.

In order to further the present knowledge of the emerging severe acute respiratory syndrome-associated coronavirus (SARS-CoV), 486 different specimens from 54 patients with a clinical diagnosis of SARS were investigated for the presence of viral RNA, and 314 plasma specimens of 73 patients were examined for IgM and IgG antibodies specific against SARS-CoV using an indirect ELISA. Viral RNA was detectable in 28 of the 54 patients tested. Cumulative data showed that 67 of the 73 SARS patients demonstrated seroconversion by week 5 of illness. In contrast, only 1 of 278 healthy subjects enrolled in the study was found to be positive for the IgG antibody. Coexistence of viral RNA in plasma and specific antibodies was simultaneously observed over three consecutive weeks in two critical cases. In three convalescent patients in particular, cultivable SARS-CoV was detected in stool or urine specimens for longer than 4 weeks (29-36 days). These findings suggest that SARS-CoV may remain viable in the excretions of convalescent patients.

Adult↗