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T Jin

Publications and source records attributed to T Jin.

At least 91 records · Page 5Linked to original sources
PubMed1994

The susceptibility of spontaneously diabetic mice to cadmium-metallothionein nephrotoxicity.

Cadmium metallothionein (CdMT) was injected subcutaneously into obese hyperglycaemic Umeå ob/ob mice or their lean litter mates (normal mice) at doses of 0, 0.1 and 0.4 mg Cd/kg. Proteinuria and calciuria were induced in both types of mice, but in the ob/ob mice this condition developed at a lower dose of CdMT (0.1 mg Cd/kg) than in the normal mice (0.4 mg Cd/kg). These results show, therefore, that Umeå ob/ob mice are particularly susceptible to CdMT-induced nephrotoxicity. The mechanism underlying this phenomenon needs to be further investigated. After the administration of CdMT, a dose-related increase in glycosuria was observed in both types of mice, in spite of decreased levels of serum insulin and glucose. It is suggested that such glycosuria induced by CdMT could be one of the signs of cadmium nephrotoxicity. The results of the present study thus indicate that metabolic changes like those in diabetes may increase susceptibility to cadmium-induced renal tubular damage.

Animals↗
PubMed1994

Identification of Neisseria gonorrhoeae in synovial fluid using the polymerase chain reaction.

OBJECTIVE: To analyze synovial fluid (SF) for the presence of Neisseria gonorrhoeae DNA using the polymerase chain reaction (PCR). METHODS: We used a modified, nested PCR to detect the presence of N gonorrhoeae DNA in 41 samples of SF obtained from 10 patients with clinical gonococcal arthritis whose SF samples were sterile by culture and from 27 controls, including 11 patients with Reiter's syndrome. Results obtained using this method were compared with those obtained using the GEN-PROBE system, an RNA-DNA hybridization technique. RESULTS: With nested PCR, N gonorrhoeae DNA was detected in 11 of 14 SF samples obtained from patients with culture-negative clinical gonococcal arthritis but in none of the 11 SF samples from Reiter's syndrome patients. The specificity of this technique was 96.4%, with a sensitivity of 78.6%. The rate of false-positive results was 3.6%. The GEN-PROBE technique was unable to detect N gonorrhoeae ribosomal RNA in any of the samples. CONCLUSION: These findings demonstrate the potential utility of the PCR in confirming the clinical diagnosis of gonococcal arthritis as well as providing insight into the pathogenesis of this disorder in patients whose SF are sterile by standard culture techniques. PCR may also prove helpful in differentiating N gonorrhoeae arthritis from acute Reiter's syndrome.

Adolescent↗
PubMed1994

Influence of zinc and copper administration on metal disposition in rats with cadmium-metallothionein-induced nephrotoxicity.

Only a few studies have investigated the effects of the interaction between Cu, Zn, and Cd on the toxicity of Cd in vivo and the metabolism of these metals. The present study is concerned with these effects. Observations of the distribution of these metals in liver and renal cortex and of their excretion in urine were made. Sixty male Wistar rats were divided into 10 groups of six (a full factorial design complemented by a center point and a control group) and were administered Zn (0 or 25 mg/kg body mass), Cu (0 or 12.5 mg/kg), and CdMT (cadmium--metallothionein; 0.1 or 0.4 mg Cd/kg) by sc injection. The rats were given Zn and/or Cu 24 hr prior to the CdMT injection. The data were analyzed by linear multiple regression. After CdMT injection, the Cd retention level was markedly reduced in renal cortex and increased in liver by Cu pretreatment, while the urinary excretion of Cd was significantly lower in these rats. The levels of endogenous Zn in renal cortex and liver increased significantly in rats pretreated with Cu. The production of MT in liver and renal cortex was induced more efficiently by Cu than by Zn. The results obtained may be of importance in understanding the mechanism of CdMT toxicity and the potential influence of Zn and Cu on the chronic nephrotoxicity of cadmium.

Animals↗
PubMed1994

Damage induced by monochromatic synchrotron x-rays at the resonance absorption energy of intracellular phosphorous in yeast cells.

Two key experiments are analysed in terms of track structure parameters to obtain information on the excessive damage observed upon the production of inner shell vacancies at the resonance energy of bound phosphorus (Kobayashi et al., 1991) and for bromine incorporated into DNA (Usami et al., 1991). The relative damage enhancement factor due to resonance in phosphorus is 1.32. Additional Auger electron cascade events induced at resonance contribute about 35% to the total effect cross-section. In the bromine experiments, the intrinsic effectiveness is shown to be less than that for phosphorus. The effects can be quantified by the equilibrium electron fluences generated, combined with a quality specification determined from the net mean free path for ionization.

Bromine↗
PubMed1994

Uniparental Mitochondrial Transmission in the Cultivated Button Mushroom, Agaricus bisporus.

A uniparental mitochondrial (mt) transmission pattern has been previously observed in laboratory matings of the cultivated mushroom Agaricus bisporus on petri dishes. In this study, four sets of specific matings were further examined by taking mycelial plugs from the confluent zone of mated homokaryons and inoculating these plugs into rye grain for laboratory fruiting and for fruiting under industrial conditions. Examination of the mt genotype of each individual fruit body for mt-specific restriction fragment length polymorphisms further confirmed that the mt genome was inherited uniparentally. The vegetative radial growth and the fruiting activity of two pairs of intraspecific heterokaryons, each pair carrying the same combination of nuclear genomes but different mt genotypes, were compared. Our results suggested that the mt genotype did not appreciably affect radial growth or fruiting activity. The failure to recover both heterokaryons, each carrying either parental mt genotype in any given cross, therefore clearly indicated that in matings of A. bisporus, the mt genome from one of the parental homokaryons is either selectively excluded in the newly formed heterokaryon or selectively eliminated in the immediate heterokaryotic mitotic progeny of the newly formed heterokaryon.

Journal Article↗
PubMed1994

Activation of proglucagon gene transcription by protein kinase-A in a novel mouse enteroendocrine cell line.

The gene encoding proglucagon is expressed predominantly in the pancreas and intestine. The physiological importance of glucagon secreted from the islets of Langerhans has engendered considerable interest in the molecular control of proglucagon gene transcription in the endocrine pancreas. In contrast, little is known about the molecular control of proglucagon gene expression in the intestine. The recent demonstration that glucagon-like peptide-1 (GLP-1) secreted from the intestine is a potent regulator of insulin secretion and glucose homeostasis has stimulated renewed interest in the factors that control GLP-1 synthesis in the intestinal L-cell. To develop a model for the analysis of intestinal proglucagon gene expression, we have targeted expression of a proglucagon gene-simian virus-40 large T-antigen fusion gene to enteroendocrine cells in transgenic mice. These mice develop intestinal tumors that were used to derive a novel cell line, designated GLUTag, that expresses the proglucagon gene and secretes immunoreactive GLP-1 in vitro. GLUTag cells demonstrate morphological characteristics of enteroendocrine cells by electron microscopy and are plurihormonal, as shown by immunocytochemistry and RNA analyses. GLUTag cells express the proglucagon and cholecystokinin genes, consistent with the pattern of lineage-specific enteroendocrine differentiation described for mouse intestine. Proglucagon gene expression was induced by activators of the protein kinase-A pathway, and a combination of messenger RNA half-life and nuclear run-on experiments demonstrated that the protein kinase-A-induction is mediated by an increase in proglucagon gene transcription. In contrast, activators of protein kinase-C stimulated secretion, but not biosynthesis of the PGDPs in GLUTag cell cultures. Analysis of proglucagon processing in GLUTag cells demonstrated the liberation of glucagon, oxyntomodulin, glicentin, and multiple forms of GLP-1. These observations provide evidence for the direct induction of proglucagon gene transcription by a cAMP-dependent pathway and suggest that the GLUTag cell line represents a useful model for the analysis of the molecular determinants of enteroendocrine gene expression.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Subcellular targets of cadmium nephrotoxicity: cadmium binding to renal membrane proteins in animals with or without protective metallothionein synthesis.

Nephrotoxic effects of cadmium exposure are well established in humans and experimental animals. An early manifestation of such toxicity is calciuria a few hours after injection of CdMT in rats. Protection against calciuria and other adverse effects such as proteinuria (occurring later) is offered by pretreatment with Cd, which effectively induces metallothionein synthesis. In the present experiment, one group of animals was given pretreatment with CdCl2 to induce metallothionein synthesis. The comparison group was left without pretreatment. The distribution of Cd from a normally nephrotoxic dose of 109CdMT was studied by gel chromatography in subcellular fractions of kidney cortex in both groups. In the pretreated animals, 109Cd in the plasma membrane and microsome fractions of renal cortical cells was mainly bound to metallothionein and other low molecular weight proteins at 4 hr. In nonpretreated animals the major part of 109Cd was bound to high molecular weight proteins. These findings indicate that membrane proteins may be important targets for Cd when inducing nephrotoxicity and that sequestering of Cd by metallothionein (and other low molecular weight proteins) may be a mechanism of protection.

Animals↗
PubMed1994

Magnetic resonance imaging of young and aged rat brains under a magnetic field of 7.05 T.

Using a homemade MR imaging probe (Helmoholtz coil), MR images of brains of 5-week-old and 23- or 24-month-old Wistar rats were taken under a magnetic field of 7.05 T (Tesla). The probe was designed to fit the rat head and made by winding thin copper film round an acrylic tube with a 5-cm i.d., 10-cm length and 2-mm thickness. This was adjusted to resonate with the 300 MHz radiofrequency corresponding to the resonance frequency of 1H under a magnetic field of 7.05 T. MR images were obtained by T1-weighted and two-dimensional Fourier transformation techniques. The sagittal and coronal sections were imaged in 1-mm-thick slices. The size of the data matrix was 128 phase-encoded steps. Each image was obtained through eight acquisitions. A comparison of the MR images with those semi-microscopically taken at the same position of the coronal section revealed that the cerebral cortex, hippocampus, hypothalamus and thalamus were clearly imaged by this probe. With aging, MR images of cerebral cortices were observed with decreased signal intensities. Enlargement of the third ventricles and hypertrophy of cranical parietal bones were also recognized in sagittal MR images of aged rats. These observations were more marked in males than in females. From these observations it was concluded that this probe was applicable for MR imaging of rat brains under a magnetic field of 7.05 T.

Aging↗
PubMed1994

[Restriction digestion of two kind of baculoviruses and the location of their p10 genes].

The length of SeNPV and LsNPV genomes DNA were calculated to be 133kb and 164kb respectively, according to digestion with 5-8 restriction endonuleases. In order to map p10 gene in Baculoviruses DNA by pure probe, two probe vectors, pAcHP106 and pAcEP102, were constructed with 3'-0. 18kb and 3'-0. 18kb + 5'-0.24kb (coding sequence and promoter) from AcNPV p10 gene. The p10 genes of both baculoviruses, SeNPV and LsNPV, are located with 0.18kb and 0.42kb probes produced by random primer labeling.

Amino Acid Sequence↗
PubMed1993

Ligand binding to the receptor domain regulates the ratio of kinase to phosphatase activities of the signaling domain of the hybrid Escherichia coli transmembrane receptor, Taz1.

Taz1 is a hybrid receptor, in which the periplasmic receptor domain of Tar, an aspartate chemoreceptor, is fused with the cytoplasmic signaling domain of EnvZ, an osmosensor. Taz1 is able to induce ompC-lacZ expression in response to aspartate added to the medium. We introduced amino acid substitution mutations in the highly conserved region of the signaling domain of Tar near the Tar-EnvZ junction. The same mutations in Tsr, a serine chemoreceptor, are known to lock the flagella rotation in either a clockwise (CW) or in a counter-clockwise (CCW) mode. It was found that a CW-biased mutation in Taz1 resulted in ompC-lacZ expression in the "off mode", or low ompC-lacZ expression in both the absence and presence of aspartate, while CCW-biased mutations caused ompC-lacZ expression in the "on mode", or constitutive expression regardless of aspartate. The OmpR kinase and phospho-OmpR phosphatase activities of the wild-type and mutant Taz proteins were also examined in response to aspartate. The phosphatase activity of the wild-type Taz1 was found to decrease in the presence of aspartate, while the OmpR kinase activity remained constant. This indicated that aspartate binding to the Taz1 receptor domain modulates the ratio of kinase to phosphatase activity of the signaling domain. An increased kinase to phosphatase ratio in the presence of aspartate resulted in higher levels of phospho-OmpR in the cell and therefore induced ompC-lacZ expression. In contrast to the wild-type Taz1 protein, the enzymatic activities of CW as well as CCW mutants did not change in response to aspartate, indicating that mutant Taz proteins are incapable of transducing the signal across the membrane as a result of a locked conformation of the signaling domain in either the on or off mode.

Aspartic Acid↗
PubMed1993

The polymerase chain reaction for the detection of Borrelia burgdorferi in human body fluids.

OBJECTIVE: To analyze clinical fluids for the presence of Borrelia burgdorferi DNA using the polymerase chain reaction (PCR). METHODS: We utilized a modified, nested PCR to detect the presence of Borrelia DNA in 99 samples of serum, urine, cerebrospinal fluid (CSF), or synovial fluid obtained from 44 patients with various stages of Lyme disease and 47 control subjects. Primer specificity was corroborated by examining 2 DNA data banks, testing against DNA from other organisms, and confirming results with a second set of nested primers. RESULTS: Nested PCR was capable of detecting DNA from fewer than 10 organisms in 1 ml of fluid. The specificity of this technique was 96.4%, with a sensitivity of 76.7%. Although the specificity was uniformly high, the sensitivity was dependent upon the body fluid being tested: CSF 100%, urine 100%, synovial fluid 80%, and serum 59%. The rate of false-positive results was 3.6%. CONCLUSION: These data demonstrate the potential utility of PCR in confirming the clinical diagnosis of Lyme disease as well as providing insight into the pathogenesis of various stages of this disorder.

Base Sequence↗
PubMed1993

Further characterization of a large inverted repeat in the mitochondrial genomes of Agaricus bisporus (= A. brunnescens) and related species.

The mitochondrial (mt) genome of Agaricus bisporus Ag50 (a heterokaryon) is a 136-kilobase (kb) circular molecule which contains a pair of large inverted repeats (IRs). Two large BAMHI fragments (B1 and B2) which contain the IR regions were further mapped. The repeated regions were determined to be approximately 7.7 kb in length. The mt small ribosomal RNA (S rRNA) gene is located adjacent to one of the repeated regions. Orientational isomers, generated by homologous recombination between the repeated regions, were not observed in mtDNA extractions from Ag50 mycelium (liquid culture) or from Ag50 fruit bodies. We also did not observe any orientational isomers in Ag50HA or Ag50HB, two homokaryons somatically isolated from Ag50. DNA homologous to the Ag50 mt repeated regions was observed in ten other isolates of Agaricus including four isolates of A. bisporus, two isolates of A. subperonatus, two isolates of A. subfloccosus, one isolate of A. bitorquis, and one isolate of A. pattersonae. The repeated regions and the small unique regions in two other heterokaryotic strains of A. bisporus, Ag2 and Ag85, were physically mapped. The repeated regions in these two strains are also in the inverted forms. Restriction endonuclease mapping indicated that the two copies of the IR in Ag85 were not identical.

Agaricus↗
PubMed1992

Components and proteolytic processing sites of arylsulfatase B from human placenta.

Previous studies have shown that mature arylsulfatase B purified from human sources is composed of two non-identical chains with apparent molecular masses of 43 kDa and 8 kDa. Arylsulfatase B purified from human placenta in the present study, however, included another 7 kDa component that could be detected only by carbohydrate staining on reducing SDS-PAGE employing the Tris-Tricine system. The 43 kDa and 7 kDa components contained a carbohydrate moiety, but the 8 kDa one did not, as demonstrated by periodic acid-Schiff staining, Con-A lectin blotting, endo-glycosidase treatment and in vitro phosphorylation by UDP-N-acetylglucosamine: lysosomal enzyme N-acetylglucosamine 1-phosphotransferase. The purified arylsulfatase B migrated as a single polypeptide of 58 kDa on non-reducing SDS-PAGE, indicating that the three chains are linked by disulfide bonds. In order to determine the origin of the components, N-terminal sequencing of the isolated polypeptides was performed. As a result, the 43, 7 and 8 kDa components were found to commence with Ala-41, Ala-424 and Asp-466, respectively. These results suggest that after removal of the signal peptide, human arylsulfatase B undergoes proteolytic processing on at least two sites during maturation.

Amino Acid Sequence↗
PubMed1992

Increased urinary excretion of zinc and copper by mercuric chloride injection in rats.

The effects of HgCl2 on urinary excretion of Zn, Cu and metallothionein at different time intervals were observed in male Wistar rats. The rats were given a daily intraperitoneal injection of 203HgCl2 (0.5 or 1.0 mg Hg kg-1) for 2 days. 203Hg, Zn, Cu and metallothionein in urine, kidney and liver were analyzed. Significant increases in urinary Zn and Cu concentrations were found in HgCl2-dosed groups. Elevated urinary Zn and Cu concentrations were accompanied by an increased metallothionein excretion in urine at different time periods. Zn concentration in urine remained elevated during the entire observation period of 7 days. There were also increased concentrations of Cu and Zn in the renal cortex in one of the two exposed groups. The results indicate that urinary Cu and Zn are related to the manifestation of renal toxicity and/or the synthesis of metallothionein in kidney induced by mercury.

Animals↗
PubMed1992

Modulation of calciuria by cadmium pretreatment in rats with cadmium-metallothionein-induced nephrotoxicity.

One group of male Wistar rats (Group B) was pretreated by a daily subcutaneous injection with CdCl2 during 5 days with increasing doses (0.5, 1, 1, 2 and 2 mg Cd/kg). Another group of rats (Group A) was daily given normal saline subcutaneously for 5 days. On the second day after the last injection, a single s.c. injection of 109Cd-metallothionein (CdMT, 0.4 mg Cd/kg) was given to each animal in both groups. Urinary calcium, protein, metallothionein (MT), N-acetyl-beta-D-glucosaminidase (NAG) and gamma glutamyltransferase (gamma-GT) were measured. In Group A, calciuria, proteinuria, metallothioneinuria and enzymuria was induced by CdMT. Calciuria reached a peak during 0-6 h after the administration of CdMT, thus appearing earlier than other effects. Enzymuria was displayed at 6-12 h for gamma-GT and 12-24 h for NAG. A prominent increase of proteinuria appeared at 24-48 h after the challenge of CdMT. In Group B, no significant increase of urinary calcium, protein, or NAG was observed after the CdMT injection and urinary gamma-GT was only slightly elevated, thus demonstrating the protective action of pretreatment. This study demonstrates for the first time that calciuria, one of the signs of cadmium nephrotoxicity, can be prevented by cadmium pretreatment. Urinary MT increased slightly during the 4-5 days of CdCl2 pretreatment. This is in accordance with previous observations that cadmium pretreatment induces new synthesis of MT which is likely to constitute the background for the resistance to the CdMT challenge to the kidney.

Acetylglucosaminidase↗
PubMed1992

Investigation of Mitochondrial Transmission in Selected Matings between Homokaryons from Commercial and Wild-Collected Isolates of Agaricus bisporus (= Agaricus brunnescens).

Ten heterokaryons of Agaricus bisporus (= Agaricus brunnescens) were shown to carry four different mitochondrial (mt) genotypes by analysis of mt restriction fragment length polymorphisms (RFLPs). Fifteen homokaryons derived from these strains were used to investigate mt inheritance in A. bisporus. One hundred eighty-nine pairings were performed in 25 different combinations. Pairings in 15 different combinations produced heterokaryons on the basis of nuclear RFLP analyses and/or fruiting trials. The mt genotype of each new intraspecies hybrid was examined by using mt RFLPs as genetic markers. Our results suggest the following. (i) Recombination between the mt genomes was not a common event. (ii) From most individual pairings, all heterokaryons carried the same mt genotype. (iii) Heterokaryons carrying either of the two possible mt genotypes were observed in certain crosses after modification of the pairing procedure. A biparental transmission pattern was demonstrated for some crosses, but there appears to be a preference for one of the mt genotypes to predominate in any specific pairing.

Journal Article↗