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Biomedical subjects

T Jin

Publications and source records attributed to T Jin.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Presinilin 1 gene polymorphism and Alzheimer's disease in Chinese].

OBJECTIVE: To detect the relationship between Presinilin 1(PS1) intronic polymorphism and Alzheimer's disease(AD) in Chinese. METHODS: PS1 intronic polymorphism was genotyped in 58 early-onset AD cases(EOAD), 65 late-onset AD cases (LOAD) and 157 age-matched controls by using PCR methods and RFLP typing. Then the association between PS1 polymorphism and AD was analyzed. RESULTS: (1) In EOAD cases, the frequency of allele 1 increased and the frequencies of allele 2 and genotype 2/2 decreased markedly, but in LOAD cases, no differences were observed. (2) EOAD was significantly associated with allele 1 (RR=2.29), P< 0.05), allele 2 (RR=0.44) and genotype 2/2(RR=0.23, P<0.05) of PS1 polymorphism, while LOAD showed no association with PS1 polymorphism. (3)PS1 polymorphism was associated with AD predominantly in non-ApoE epsilon4, female, early-onset cases. CONCLUSION: PS1 polymorphism was only associated with EOAD in Chinese, and this may be influenced by age of onset and sex.

Aged↗
PubMed1999

c-kit<low Pluripotent hemopoietic stem cells form CFU-S on day 16.

Using Ly5 congenic mice, we characterized the early differentiation step of pluripotent hemopoietic stem cells. Lineage- (Lin-)/CD71- cells in the bone marrow cells were separated into major histocompatibility complex (MHC) class I(high)/c-kit(low) and MHC class I(high)/c-kit<low populations from C57BL/6 Ly5.1 male mice. These two populations (1,000 cells) were transplanted into lethally irradiated (5.5 Gy x 2) C57BL/6 Ly5.2 female mice. Colony-forming unit in spleen (CFU-S) assays were carried out on days 10, 12, 14, 16, and 20. In the mice that received c-kit(low) cells, CFU-S were first detected on day 12, and the CFU-S counts gradually increased. In contrast, no visible colony was detected until day 14 in the mice that received c-kit<low cells; CFU-S were first observed on day 16. Donor-derived (Ly5.1+) cells, such as B cells, T cells, and myeloid cells, were detected by fluorescence-activated cell sorter analyses, and donor-derived erythroid cells were detected by polymerase chain reaction analyses using Y-chromosome-specific primers. Donor-derived cells in the recipients of c-kit(low) cells were detected in the spleen, bone marrow, and peripheral blood on day 12 after transplantation, while they were detected on day 16 in the mice that received c-kit<low cells. Therefore, c-kit<low cells have the capacity not only to form CFU-S on day 16 but also to reconstitute the recipients with donor-derived hematolymphoid cells 16 days after transplantation.

Animals↗
PubMed1999

Urinary N-acetyl-beta-D-glucosaminidase isoenzymes as biomarker of renal dysfunction caused by cadmium in a general population.

N-Acetyl-beta-D-glucosaminidase (NAG) and its isoenzymes in urine have been studied in a population group residing in a polluted area in China. The area studied was contaminated by industrial wastewater from a nearby smelter that discharged cadmium-polluted wastewater into a river used for the irrigation of rice fields. Cadmium concentrations in rice were 3.70, 0.51, and 0.07 mg/kg for the highly and moderately polluted areas and the control area, respectively. Cadmium concentrations in urine exceeded 5 microgram/liter in the majority of subjects in the most highly polluted area. There was a marked dose-dependent increase in NAG and NAG B content of urine related both to urinary cadmium and to the calculated cadmium uptake. It is concluded that urinary NAG and its isoenzymes could serve as a sensitive biomarker of renal dysfunction in cadmium-exposed populations. The mechanisms underlying the increase in NAG and its isoenzymes after cadmium exposure need to be studied further.

Acetylglucosamine↗
PubMed1999

Persistent tolerance induced after portal venous injection of allogeneic cells plus cyclophosphamide treatment.

The injection of allogeneic cells via the portal vein (p.v.) is known to reduce responses to donor-alloantigens. In the present study, we have obtained persistent tolerance across Mls and multiple minor histocompatibility complexes by p.v. preimmunization followed by the administration of cyclophosphamide (CY). A hundred percent survival of (BALB/c x DBA/2)F1 (CDF1) skin grafts for more than 200 days was observed when BALB/c mice were preimmunized with spleen cells of CDF1 (3 x 10(7)) via the p.v. and administered 300 mg/Kg CY 2 days after the p.v. injection. Comparable survival of the skin graft was observed when bone marrow cells instead of spleen cells were p.v. preimmunized. However, the survival rate was significantly decreased when LPS-stimulated blastic cells were p.v. preimmunized. Microchimerism has been observed in the liver, thymus, bone marrow and peripheral blood of recipients. V beta 6+ cells decreased in CD4+ cells of recipients of the p.v. preimmunization plus CY treatment. However, there was no difference in the decrease in V beta 6+ cells between recipients accepting the CDF1 skin grafts and recipients that had rejected the skin grafts. Furthermore, no intrathymic depletion of the V beta 6+ cells was observed. From these results, it is suggested that, rather than clonal deletion, other mechanisms such as clonal anergy or suppression may be involved in the induction of persistent tolerance after the p.v. preimmunization plus CY treatment.

Animals↗
PubMed1999

Mechanical properties of several nickel-titanium alloy wires in three-point bending tests.

The purpose of this study was to clarify the mechanical properties of 42 brands of nickel-titanium alloy orthodontic wires from 9 manufacturers by conducting three-point bending tests under uniform testing conditions. Manufacturers included A-Company, Hoya Medical, Lancer, Ormco, Rocky Mountain, Sankin, Tomy (GAC), TP, and 3M/Unitek. Cobalt-chrome, and titanium-molybdenum alloy wires were also tested as a reference for comparison of force levels. All reported data were recorded during the unloading process to simulate the force that a wire exerts on a tooth as it is moved into the dental arch from a position of malocclusion. The following results were obtained for the nickel-titanium wires tested. (1) Among the 0.016 inch round wires tested under a maximum deflection of 1.5 mm, the difference between the smallest (Copper nickel-titanium 35) and the largest (Aline) load values was 136 g. For the 0.016 x 0.022 inch rectangular wires tested, the difference between the smallest (Copper nickel-titanium 40) and the largest (Aline) load values was 337 g. (2) The change in load between 1.5 and 0.5 mm of deflection was examined to clarify the superelastic properties of the wires tested. For the 0.016 inch wires, 17 wire brands produced a load difference of less than 100 g, and two brands produced a difference of at least 100 g (Aline and Titanal = 100 g). For the 0.016 x 0.022 inch wires, 15 brands produced a load difference of less than 100 g, and eight brands produced a difference of over 100 g. The smallest and largest load differences were 3 g (Copper nickel-titanium 35) and 200 g (Aline). (3) The majority of the samples with a smaller load difference between deflections of 1.5 mm and 0.5 mm in the unloading process were found among super-elastic wires, while samples with a larger load difference were predominantly found among work-hardened wires. Compared with cobalt-chrome and TMA wires, nickel-titanium alloy wires exert significantly less force. However, the amount of force varies greatly from brand to brand. Consequently, when using nickel-titanium alloy wires, brands must be selected carefully by taking into consideration the severity of the malocclusion and the stage of orthodontic treatment in each case. It is the intent of this study to offer clinicians an unbiased guide for the selection of appropriate nickel-titanium alloy wires.

Dental Alloys↗
PubMed1999

Nucleotide sequence of a 5892 base pairs fragment of the LsMNPV genome and phylogenetic analysis of LsMNPV.

A 5892 bp fragment of Leucania separata multiple nuclear polyhederosis virus (LsMNPV) containing gp37, 39 k genes and another four ORFs was sequenced in this article. According to regulatory elements on 5' uncoding sequences, the ORF4 and ORF1 are probably two novel baculovirus genes, and the ORF4 probably also is a new early-late gene. The possible functions about GP37 and 39 K proteins were explored. The homology of GP37 protein among LsMNPV and 8 other insect virus was compared. The evolutional position of LsMNPV is also estimated based on the homology of gp37 genes. The structure and its homology of several genes in LsMNPV prove that LsMNPV is far related with other baculovirus and has an exceptional genome organization.

Amino Acid Sequence↗
PubMed1999

Apoptosis and p53 gene expression in male reproductive tissues of cadmium exposed rats.

Reverse transcription (RT) PCR technique was used to investigate the mechanism of apoptosis induced by Cd and the change of its related genes in testes and prostate of rats. Adult male rats were given a single (s.c.) injection of CdCl2 0, 2.5, 5.0, 10 mumol/kg. 48 h and 72 h after administration of Cd, animals were sacrificed. The results indicated that Cd can induce apoptosis in testes via p53-independent pathway. No apoptosis occurred in prostate in any of the Cd-exposed groups. There was a clearly negative relationship in testes between p53 gene expression and Cd exposure and this dose-response relationship was observed both at 48 h and 72 h. There was a very small increase of this gene expression in the dorsolateral lobe of the prostate in Cd exposed groups. The other apoptosis related gene, bcl-x, was not detectable in either control or Cd-exposed group in testes and dorsal prostate. Although the MT-I gene was expressed in testes or dorsal prostate both in control and exposed groups, no overexpression of MT-I gene was found after administration of Cd. The expression of MT-I in the ventral prostate was not detected in the control group, but a weak expression was found after Cd exposure. Since p53 is a tumor suppressor gene which can inhibit tumorigenesis, the consequence of a Cd-induced decrease of p53 in testes may have a relation to the known risk of Cd tumorigenesis in this tissue.

Animals↗
PubMed1999

[The relation between alpha1-antichymotrypsin gene polymorphism and epsilon4 allele of apolipoprotein E gene in Alzheimer disease in Chinese].

OBJECTIVE: To detect the relation between alpha1-antichymotrpsin(AACT)gene polymorphism and epsilon4 allele of apolipoprotein E (ApoE) gene in Alzheimer disease (AD) in Chinese. METHODS: The gene polymorphisms of ApoE and AACT were genotyped in 125 AD cases and 140 controls with PCR methods and RFLP typing. Then the association between AACT polymorphism and ApoE epsilon4 was analysed. RESULTS: There was no association between AD and any allele or genotype of AACT polymorphism; AACT polymorphism was not associated with AD ApoE epsilon4 or without ApoE epsilon4. In AACT*AT and AACT*TT genotypes, ApoE epsilon4 allele was associated with AD, but no association was observed in AACT*AA genotype. CONCLUSION: AACT may not be associated with AD in Chinese, and this effect can not be influenced by ApoE epsilon4, but AACT gene polymorphism may affect the association between ApoE epsilon4 allele and AD.

Adult↗
PubMed1998

Temperature-sensitive Gbeta mutants discriminate between G protein-dependent and -independent signaling mediated by serpentine receptors.

Deletion of the single gene for the Dictyostelium G protein beta-subunit blocks development at an early stage. We have now isolated temperature-sensitive alleles of Gbeta to investigate its role in later development. We show that Gbeta is directly required for adenylyl cyclase A activation and for morphogenetic signaling during the entire developmental program. Gbeta was also essential for induction of aggregative gene expression by cAMP pulses, a process that is mediated by serpentine cAMP receptors (cARs). However, Gbeta was not required for cAR-mediated induction of prespore genes and repression of stalk genes, and neither was Gbeta needed for induction of prestalk genes by the differentiation inducing factor (DIF). cAMP induction of prespore genes and repression of stalk genes is mediated by the protein kinase GSK-3. GSK-3 also determines cell-type specification in insects and vertebrates and is regulated by the wingless/wnt morphogens that are detected by serpentine fz receptors. The G protein-dependent and -independent modes of cAR-mediated signaling reported here may also exist for the wingless/wnt signaling pathways in higher organisms.

Adenylyl Cyclases↗
PubMed1998

G protein beta subunit-null mutants are impaired in phagocytosis and chemotaxis due to inappropriate regulation of the actin cytoskeleton.

Chemotaxis and phagocytosis are basically similar in cells of the immune system and in Dictyostelium amebae. Deletion of the unique G protein beta subunit in D. discoideum impaired phagocytosis but had little effect on fluid-phase endocytosis, cytokinesis, or random motility. Constitutive expression of wild-type beta subunit restored phagocytosis and normal development. Chemoattractants released by cells or bacteria trigger typical transient actin polymerization responses in wild-type cells. In beta subunit-null cells, and in a series of beta subunit point mutants, these responses were impaired to a degree that correlated with the defect in phagocytosis. Image analysis of green fluorescent protein-actin transfected cells showed that beta subunit- null cells were defective in reshaping the actin network into a phagocytic cup, and eventually a phagosome, in response to particle attachment. Our results indicate that signaling through heterotrimeric G proteins is required for regulating the actin cytoskeleton during phagocytic uptake, as previously shown for chemotaxis. Inhibitors of phospholipase C and intracellular Ca2+ mobilization inhibited phagocytosis, suggesting the possible involvement of these effectors in the process.

Actins↗
PubMed1998

A strategy for organ allografts without using immunosuppressants or irradiation.

A strategy to achieve regular and long lasting organ and tissue allografts without using immunosuppressants and/or irradiation has been established for mice. One hundred percent of skin allografts can be induced to survive >350 days after transplantation if spleen cells from the same donors are first injected into the portal vein of the recipients. The mechanisms underlying this long-term tolerance induction can be described as follows: (i) donor T cells from the spleen of the donor facilitate the acceptance of the allogeneic engraftment, (ii) donor-specific anergy is induced in the cytotoxic T-lymphocytes of the recipients, (iii) T helper type 2 cells become the dominant T cells in the recipients that are accepting the skin transplants, and (iv) a lasting chimerism (microchimerism) is established in these recipients. This strategy, perhaps with minor modifications, might permit one also to overcome major barriers to organ allografting in humans. If this were the case, it could represent production of long lasting immunologic tolerance without need for irradiation or cytotoxic chemo-preparative regimen and as such could greatly facilitate allotransplantation free of episodes of chronic or acute rejection or toxic and damaging preparatory regimens.

Adoptive Transfer↗
PubMed1998

Stimulatory effects of hepatocyte growth factor on hemopoiesis of SCF/c-kit system-deficient mice.

In this study, we report that W/W mutant mice, which have severe macrocytic anemia caused by a deficit of extracellular domain in c-kit molecules and therefore die perinatally, have hemopoietic stem cells (HSCs) and mature hematolymphoid cells in the bone marrow (BM), thymus, and spleen, although there are significant decreases in cell counts. Moreover, the mitogen-induced proliferative response, mixed lymphocyte reaction, and anti-SRBC plaque formation of spleen cells in W/W mice are similar to those in age-matched +/? littermates and normal mice, suggesting that the SCF/c-kit system is necessary for cell proliferation but not essential for HSCs to differentiate. We next examine the stimulatory effects of hepatocyte growth factor (HGF) on hemopoiesis in W/W mice. HGF has a stimulatory effect on the colony formation (CFU-C) of W/W BM cells when cultured using either a methylcellulose assay (containing cytokines) or a long-term culture (LTC) assay. A similar stimulatory effect of HGF is observed in the other W or SI locus-mutant mice (W/Wv and SI/SId mice), which show less severe anemia than W/W. The numbers of nonadherent cells and cobblestone colonies significantly increase in the LTCs using their BM cells. In addition, in vivo administration of HGF shows a transient increase in the CFU-C counts in BM cells and peripheral blood cells. RBC, WBC, and platelet counts also increased. These results suggest that the SCF/c-kit system is not essential to hemopoiesis but that a compensatory system such as the HGF/c-met system functions in the SCF/c-kit system-deficient mice.

Anemia, Macrocytic↗
PubMed1998

Selection of gbeta subunits with point mutations that fail to activate specific signaling pathways in vivo: dissecting cellular responses mediated by a heterotrimeric G protein in Dictyostelium discoideum.

In Dictyostelium discoideum, a unique Gbeta subunit is required for a G protein-coupled receptor system that mediates a variety of cellular responses. Binding of cAMP to cAR1, the receptor linked to the G protein G2, triggers a cascade of responses, including activation of adenylyl cyclase, gene induction, actin polymerization, and chemotaxis. Null mutations of the cAR1, Galpha2, and Gbeta genes completely impair all these responses. To dissect specificity in Gbetagamma signaling to downstream effectors in living cells, we screened a randomly mutagenized library of Gbeta genes and isolated Gbeta alleles that lacked the capacity to activate some effectors but retained the ability to regulate others. These mutant Gbeta subunits were able to link cAR1 to G2, to support gene expression, and to mediate cAMP-induced actin polymerization, and some were able to mediate to chemotaxis toward cAMP. None was able to activate adenylyl cyclase, and some did not support chemotaxis. Thus, we separated in vivo functions of Gbetagamma by making point mutations on Gbeta. Using the structure of the heterotrimeric G protein displayed in the computer program CHAIN, we examined the positions and the molecular interactions of the amino acids substituted in each of the mutant Gbetas and analyzed the possible effects of each replacement. We identified several residues that are crucial for activation of the adenylyl cyclase. These residues formed an area that overlaps but is not identical to regions where bovine Gtbetagamma interacts with its regulators, Galpha and phosducin.

Adenylyl Cyclases↗
PubMed1998

In vitro reconstitution of electron transport from glucose-6-phosphate and NADPH to nitrite

An NADPH-dependent NO2--reducing system was reconstituted in vitro using ferredoxin (Fd) NADP+ oxidoreductase (FNR), Fd, and nitrite reductase (NiR) from the green alga Chlamydomonas reinhardtii. NO2- reduction was dependent on all protein components and was operated under either aerobic or anaerobic conditions. NO2- reduction by this in vitro pathway was inhibited up to 63% by 1 mm NADP+. NADP+ did not affect either methyl viologen-NiR or Fd-NiR activity, indicating that inhibition was mediated through FNR. When NADPH was replaced with a glucose-6-phosphate dehydrogenase (G6PDH)-dependent NADPH-generating system, rates of NO2- reduction reached approximately 10 times that of the NADPH-dependent system. G6PDH could be replaced by either 6-phosphogluconate dehydrogenase or isocitrate dehydrogenase, indicating that G6PDH functioned to: (a) regenerate NADPH to support NO2- reduction and (b) consume NADP+, releasing FNR from NADP+ inhibition. These results demonstrate the ability of FNR to facilitate the transfer of reducing power from NADPH to Fd in the direction opposite to that which occurs in photosynthesis. The rate of G6PDH-dependent NO2- reduction observed in vitro is capable of accounting for the observed rates of dark NO3- assimilation by C. reinhardtii.

Journal Article↗
PubMed1998

Renal dysfunction from cadmium contamination of irrigation water: dose-response analysis in a Chinese population.

In a cadmium-contaminated area in China and a nearby non-contaminated area, 342 persons were selected for studies of a possible relationship between cadmium dose (i.e. total cadmium intake) and response in terms of renal dysfunction. An increase in urinary excretion of beta-2-microglobulin (UB2M), adjusted for age and sex, was used as an indicator of the response. A statistically significant relationship was found between measured cadmium concentrations in whole blood (range; < 3.5 to > 15 micrograms/l) and UB2M, and there was a statistically significant linear trend. Also, cadmium in urine (< 4 to > 16 micrograms/g creatinine) and UB2M displayed a statistically significant positive relationship when the total data set was analysed for males and females. The relationship between a dose index (obtained from calculated cumulative absorbed doses over a lifetime) and UB2M was statistically significant. The results of this first study on dose-response relationships in a Chinese population are similar to those observed in other populations.

Adult↗
PubMed1997

Biological monitoring of cadmium exposure and renal effects in a population group residing in a polluted area in China.

In an area of China, not previously studied in detail concerning cadmium pollution and possible adverse effects on the kidney of exposed populations, concentrations of cadmium in urine as an indicator of renal accumulation of cadmium was studied and related to indicators of renal dysfunction in order to examine if a relationship could be documented. Cadmium concentrations in urine were analysed by graphite furnace atomic absorption spectrometry and urinary beta-2 microglobulin (UBM) and albumin (UALB) were measured as indicators of renal dysfunction, Rice samples and urine samples were obtained from three areas in Zhejiang province, China, representing a highly exposed area, a medium exposed area and a control area, respectively. Cadmium concentrations in rice were 3.70, 0.51 and 0.072 mg/kg for the heavily, medium polluted areas and the control area, respectively. Cadmium concentrations in urine (geometric means) were 10.7, 1.62 and 0.40 micrograms/l in the high, medium and control areas respectively. There was a clear increase in UBM and UALB in the heavily exposed group in comparison to the control group and a slight increase in the medium exposed group. There was a statistically significant dose-response relationship between cadmium in urine and beta 2-microglobulin excretion in urine, which is similar to what has previously been reported in other countries. The findings constitute the first report concerning a dose-response relationship in this population group in Zhejiang province in China.

Adult↗
PubMed1997

Intrathymically injected hemopoietic stem cells can differentiate into all lineage cells in the thymus: differences between c-kit+ cells and c-kit < low cells.

To investigate whether hemopoietic stem cells (HSCs) can differentiate into all lineage cells even in the thymus, we injected two types of HSCs (c-kit+ and c-kit < low cells) obtained from C57BL/6 Ly5.1 mice directly into the thymus of 7.5 Gy-irradiated C57BL/6 Ly5.2 mice. When c-kit < low cells (low density/lineage-/CD71-/major histocompatibility complex class I high/Sca-1+/Thy-1low/ c-kit < low) were injected, donor-derived (Ly5.1) cells were detected on day 8 after intrathymic (i.t.) injection, and the number reached a maximum on day 24 after injection. Granulocytes and macrophages were also detected on day 8 after injection. However, B220+ B cells were observed on day 13. Eighteen days after i.t. injection, the injected lobes showed red color due to the synchronous development of erythroid cells. Histological studies revealed the development not only of erythroid lineage cells but also of megakaryocytes in the thymus. In contrast, when c-kit+ cells were injected, a significant number of donor-derived cells were detected on day 5 after i.t. injection (three days earlier than in the case of c-kit < low cell injection). The differentiation into erythroid lineage cells was also observed six days earlier than when c-kit < low HSCs were injected. These findings suggest that c-kit < low HSCs are more primitive than c-kit+ HSCs, although both can differentiate into all lineage cells after i.t. injection.

Animals↗