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Biomedical subjects

S Jin

Publications and source records attributed to S Jin.

At least 235 records · Page 13Linked to original sources
PubMed1994

Transcriptional regulation of Bacillus subtilis citrate synthase genes.

The Bacillus subtilis citrate synthase genes citA and citZ were repressed during early exponential growth phase in nutrient broth medium and were induced as cells reached the end of exponential phase. Both genes were also induced by treatment of cells with the drug decoyinine. After induction, the steady-state level of citZ mRNA was about five times higher than that of citA mRNA. At least some of the citZ transcripts read through into the isocitrate dehydrogenase (citC) gene. Transcription from an apparent promoter site located near the 3' end of the citZ gene also contributed to expression of citC. In minimal medium, citA transcription was about 6-fold lower when glucose was the sole carbon source than it was when succinate was the carbon source. Expression of the citZ gene was repressed 2-fold by glucose and 10-fold when glucose and glutamate were present simultaneously. This latter synergistic repression is similar to the effect of glucose and glutamate on steady-state citrate synthase enzyme activity. CitR, a protein of the LysR family, appeared to be a repressor of citA but not of citZ.

Aconitate Hydratase↗
PubMed1994

Nucleotide sequence of the rpoN gene and characterization of two downstream open reading frames in Pseudomonas aeruginosa.

The rpoN gene of Pseudomonas aeruginosa is required for the expression of a number of diverse genes, ranging from several classes of bacterial adhesins to enzymes for amino acid biosynthesis. The nucleotide sequence of the rpoN gene and its flanking region has been determined. The deduced amino acid sequence of the rpoN product is highly homologous to sequences of RpoN proteins of other microorganisms. Moreover, two open reading frames (ORF1 and ORF2) encoding peptides of 103 and 154 amino acids long, respectively, were found downstream of the rpoN gene. These two ORF products have a high degree of amino acid sequence homology with products of similar ORFs located adjacent to the rpoN genes in other microorganisms. Mutations in either ORF lead to a significant increase in P. aeruginosa generation time when propagated on minimal medium. These mutations had no effect on the expression of pilin or flagellin genes, whose expression depends on RpoN. Complementation analysis showed that the two ORFs are in the same transcriptional unit and the growth defects of the two ORF mutants on minimal medium are due to mutational effects on ORF2. The adverse effect of the ORF mutations on the growth of P. aeruginosa in minimal media can be suppressed by the addition of glutamine but not arginine, glutamate, histidine, or proline. Since rpoN mutants of P. aeruginosa display this same amino acid requirement for growth, the ORF2 product very likely functions as a coinducer of some but not all of the RpoN-controlled genes.

Amino Acid Sequence↗
PubMed1994

Identification of a point mutation in the thyrotropin receptor of the hyt/hyt hypothyroid mouse.

The hyt/hyt hypothyroid mouse has an autosomal recessive, fetal-onset, severe hypothyroidism related to TSH hyporesponsiveness and associated with elevated TSH. Our previous work has suggested that the hypothyroidism and TSH hyporesponsiveness may result from a mutation in the hyt/hyt TSH receptor (TSHr) of the thyroid gland. Based on DNA sequencing of the entire coding region of the TSHr gene from the wild-type BALB/cBY +/+ mouse, the +/+ TSHr is 92% and 94% identical at the nucleotide and amino acid residue levels, respectively, compared to the rat TSHr gene. The coding region of the hyt/hyt TSHr, compared to that of the +/+ TSHr, has a single base change, CCG to CTG, at nucleotide position 1666, which leads to the replacement of a highly conserved proline at amino acid position 556 with a leucine in transmembrane domain IV. This mutation was introduced by site-directed mutagenesis into the wild-type human TSHr and transiently expressed in COS-7 cells. Although the size and abundance of the mutant TSHr mRNA suggested that there was no effect on the nature of the mRNA, TSH binding and the response to TSH in transfected cells were abolished. Further studies are necessary to clarify how the Pro to Leu replacement interferes with receptor expression on the cell surface or influences TSH binding. These functional consequences of the mutation appear to account for the observed TSH hyporesponsiveness and hypothyroidism in the hyt/hyt mouse.

Amino Acid Sequence↗
PubMed1994

[Research on Atlas of Viscera].

Chinese ancient visceral atlas, or anatomical illustrations were derived from Taoist and medical schools through observation in cadavers. During the period from Five-Dynasties to Song, there were several works on visceral atlas, including Yanluo illustration, Atlas of Ou Xifan's visceral atlas of fidelity, Li Jung's Atlas. Among them, there exist relations of transmission-heredity, with gradual improvement. It seems likely that the visceral illustrations in Japanese Wan'an Prescription is the extant illustration of Ou's. After the advent of Atlas of Fidelity visceral atlas was differentiated into 3 different kinds of illustrations, as the Inner Picture (Neijing) of Mingtang Atlas; Neizhao Picture in pulsological works and visceral picture in physical Shenxing picture. Chinese visceral atlas was transmitted to Japan, Korea, Persia, and Europe and exerted some influence on cosmopolitan medicine.

China↗
PubMed1994

Distribution of red cell blood groups in Han subpopulations of Inner Mongolia, Gansu and Henan Provinces, China.

Three Han subpopulations, Gansu, Henan, and Inner Mongolia were examined for red cell blood group systems, including ABO, Rh, MNSs, Kidd, Duffy, Diego, and Xg. There was no MS type in Gansu, no SS type in Henan and no MNS and NS types in Inner Mongolia, no CCDE- and CcDEE types in Henan, and no ccDee type in Inner Mongolia. The gene frequencies of S (0.0975) and P1 (0.2584) as well as the MS haplotype frequency (0.0629) in Gansu were the highest, while the Di(a) gene frequency (0.0151) in Henan was the lowest among the subpopulations of Han nationality studied so far. The Xg(a) gene frequency in Henan was 0.6055, the highest value observed in China. The genetic distances and phylogenetic tree of eight Han subpopulations showed that the Han in Henan were closest to the Han in Inner Mongolia, and that the Han in Fujian were closest to the Han in Guizhou among others.

Blood Group Antigens↗
PubMed1994

[Clinical application of rhombotrapezious island musculocutaneous flap for skull base and/or craniomaxillary operation with malignant tumor].

Regional pedicled musculocutaneous flaps are the mainstay of the head and neck reconstruction. They provide a rapid, highly reliable and single-staged technique that is applicable in most cases. The rhombotrapezious island musculocutaneous flap is valuable in the base and craniomaxilloface reconstruction. In this study we updated our experience with the rhombotrapezious island musculocutaneous flap (RTIMF) in 6 cases from 1989 to 1993. Dissections were performed on 9 cadavers, 4 preserved and 5 fresh, yielding 18 pairs or dorsal scapular and transverse cervical artery for evaluation. In the five fresh cadavers, the arteries were selectively cannulated and injected with colored latex. 67% with dorsal scapular and transverse cervical artery commonly arose from the thyro-cervical trunk. 33% with the dorsal scapular artery directly arose from the second part of the subclavian artery. In the period of 1989-1993, 6 rhombotrapezious island musculocutaneous flaps with vascularized pedicle were used for immediate repair in the skull base or craniomaxillary cancer operations. There was no complication of the flaps. Donor site complications were relatively minor. The disturbance in shoulder function was well tolerated. We advocated the incorporation of both the greater and lesser rhomboid muscle to form the compound rhombotrapezious flaps to enhance the vascular supply to the overlying skin. The major advantage of the RTIMF are that it provides a long paddle of thin pliant, hairless skin and muscle that can be rotated as far as the craniomaxilloface and scalp in a single stage. It offers the longest arc of rotation and thus the greatest versatility for the skull base or craniomaxillary reconstruction.

Adult↗
PubMed1994

[The trend of mortality of lung cancer and its association with air pollution].

A death retrospective survey of all causes from 1985 to 1989 was carried out in thirteen districts of Shandong Province in 1990. The total population investigated was 8.10 million that accounted for nearly ten percent of the whole population of Shandong. The death rate of lung cancer (adjusted by Chinese population in 1964) was 12.0 per 100,000 population. As compared with that in 1970-1974, it increased by 96.7%, of which 102.5% for male and 85.7% for female. In each district the mortality of lung cancer also went up. In Qingtao, Jinan, and Zibo with high-mortality in 1970-1974, the rates of lung cancer death increased by 213%, 291%, and 260%, respectively. At the same time, in Zhaozhuang, Jining, Hezie with low-mortality in 1970-1974, the mortality rates of lung cancer increased by 303%, 284% and 285%, respectively. The results of correlational analysis showed that the increasing rate of lung cancer was related to the air pollution.

Air Pollutants↗
PubMed1993

Preformed dimeric state of the sensor protein VirA is involved in plant--Agrobacterium signal transduction.

Plant signal molecules such as acetosyringone and certain monosaccharides induce the expression of Agrobacterium tumefaciens virulence (vir) genes, which are required for the processing, transfer, and possibly integration of a piece of the bacterial plasmid DNA (T-DNA) into the plant genome. Two fo the vir genes, virA and virG, belonging to the bacterial two-component regulatory system family, control the induction of vir genes by plant signals. virA encodes a membrane-bound sensor kinase protein and virG encodes a cytoplasmic regulator protein. Although it is well established from in vitro studies that the signal transduction process involves VirA autophosphorylation and subsequent phosphate transfer to VirG, the structural state of the VirA protein involved in signal transduction is not understood. In this communication, we describe an in vivo crosslinking approach which provides physical evidence that VirA exists as a homodimer in its native configuration. The dimerization of VirA neither requires nor is stimulated by the plant signal molecule acetosyringone. We also present genetic data which support the hypothesis that VirA exists as a homodimer which is the functional state transducing the plant signal in an intersubunit mechanism. To our knowledge, this report provides the first evidence that a bacterial membrane-bound sensor kinase exists and functions as a homodimer in vivo.

Agrobacterium tumefaciens↗
PubMed1993

The interleukin-12 subunit p40 specifically inhibits effects of the interleukin-12 heterodimer.

The recently discovered cytokine interleukin (IL)-12 is a heterodimeric protein of two disulfide-bonded subunits of 35 and 40 kDa. IL-12 has multiple effects on T cells and natural killer (NK) cells. In particular it appears to be a major factor for the development of cellular immunity. So far activity of the single subunits alone has not been described, however their expression is regulated independently. In this report we demonstrate for the first time that the mouse IL-12 subunit p40 (IL-12p40) specifically antagonizes the effects of the IL-12 heterodimer in different assay systems. The proliferation of mouse splenocytes activated by phorbol ester and IL-12 was inhibited by IL-12p40, whereas the proliferation induced by phorbol ester and IL-2 was not affected. Furthermore, the synthesis of interferon (IFN)-gamma by mouse splenocytes activated with IL-2 and IL-12 was suppressed by IL-12p40. Purified mouse splenic CD4+ T cells produced IFN-gamma upon activation with plate-bound anti-CD3 monoclonal antibody which was enhanced more than tenfold in the presence of IL-12. In this system IL-12p40 inhibited only the enhancement caused by IL-12 but not IFN-gamma synthesis of CD4+ T cells stimulated with anti-CD3 alone. Moreover, IL-12p40 inhibited the effects of IL-12 on differentiated T helper type 1 (Th1) cells. IFN-gamma production by Th1 cells induced in a T cell receptor-independent way by macrophages and IL-2 or macrophages and IL-12 was greatly reduced by IL-12p40 providing evidence for the endogenous synthesis of IL-12 in the Th1 cell, macrophage and IL-2 co-cultures. The specificity of inhibition was clearly demonstrated in the homotypic aggregation assay of Th1 cells. Incubation of Th1 cells with either IL-2 and IL-12 or IL-2 and tumor necrosis factor induces LFA-1/ICAM-1-dependent aggregation. Only IL-2 + IL-12 but not IL-2 + tumor necrosis factor-induced aggregation was inhibited in a dose-dependent manner by IL-12p40. Thus, the IL-12 subunit p40 appears to be a specific inhibitor for the IL-12 heterodimer.

Animals↗
PubMed1993

High-affinity fatty acid-binding activity in epidermis and cultured keratinocytes is attributable to high-molecular-weight and not low-molecular-weight fatty acid-binding proteins.

Fatty acid-binding proteins (FABPs) are abundant low-molecular-weight cytosolic proteins in tissues involved in fatty acid (FA) metabolism. Because epidermis is also an active lipogenic tissue, we examined cytosols from murine and porcine epidermis and cultured human keratinocytes and fibroblasts for FABPs. High-affinity FA-binding activity was present in both epidermis and differentiated keratinocytes, whereas no high-affinity FA-binding activity was found in cultured human fibroblasts or undifferentiated keratinocytes. By column chromatography, a single binding peak was identified in the high (90-100 kDa)-molecular-weight range and no binding activity was evident in the low (14-15 kDa)-molecular-weight range, where conventional FABPs elute. Moreover, rabbit anti-rat heart FABP, anti-rat intestine FABP, and anti-rat liver FABP antisera did not identify proteins in the 14-15-kDa range in murine epidermal cytosol by Western immunoblots, whereas the anti-rat-heart antibody recognized a protein of approximately 32 kDa. Isoelectric focusing of differentiated keratinocyte cytosol demonstrated a single FA-binding peak having a pI of approximately 4.0. Analysis of this binding peak by SDS-PAGE revealed peptides of approximately 66 and 38 kDa. These findings suggest the possibility that the FA-binding protein in keratinocyte cytosol normally exists as a heterodimer. Western immunoblots of both differentiated keratinocyte cytosol and keratinocyte-conditional media stained with a rabbit anti-human serum albumin antibody identified a protein of approximately 67 kDa, but the electrofocused fraction did not react with this antibody. Thus, epidermis and differentiated keratinocytes possess high-affinity cytosolic FA-binding activity that cannot be ascribed either to conventional low-molecular-weight FABPs or to albumin.

Binding, Competitive↗
PubMed1993

Characterization of a virG mutation that confers constitutive virulence gene expression in Agrobacterium.

Transformation of plants by Agrobacterium tumefaciens is mediated by a set of virulence (vir) genes that are specifically induced by plant signal molecules through the VirA/VirG two-component regulatory system. The plant signal is transmitted from VirA to VirG by a cascade of phosphorylation reactions followed by the sequence-specific DNA binding of the VirG protein to the vir gene promoters which then activates their transcription. In this report, we describe a VirG mutant which is able to activate vir gene expression independently of the VirA molecule and the two plant signal molecules, acetosyringone and monosaccharides. A strain of Agrobacterium containing this virG gene but lacking a functional virA gene was able to induce tumours on all three plants that were tested. A single amino acid change of asparagine (N) to aspartate (D) at position 54, adjacent to the site of VirG phosphorylation, aspartate 52, resulted in this constitutive phenotype. In vitro phosphorylation experiments showed that the mutant protein cannot be phosphorylated by VirA, suggesting that the negative charge resulting from the N to D switch mimics the phosphorylated conformation of the VirG molecule. The same amino acid change in the virG gene of the supervirulent strain A281 also resulted in a constitutive phenotype. However, the vir genes were not induced to high levels when compared with the levels of the constitutive virG of strain A348.

Agrobacterium tumefaciens↗
PubMed1993

The regulatory VirA protein of Agrobacterium tumefaciens does not function at elevated temperatures.

Previous studies have shown that Agrobacterium tumefaciens causes tumors on plants only at temperatures below 32 degrees C, and virulence gene expression is specifically inhibited at temperatures above 32 degrees C. We show here that this effect persists even when the virA and virG loci are expressed under the control of a lac promoter whose activity is temperature independent. This finding suggests that one or more steps in the signal transduction process mediated by the VirA and VirG proteins are temperature sensitive. Both the autophosphorylation of VirA and the subsequent transfer of phosphate to VirG are shown to be sensitive to high temperatures (> 32 degrees C), and this correlates with the reduced vir gene expression observed at these temperatures. At temperatures of 32 degrees C and higher, the VirA molecule undergoes a reversible inactivation while the VirG molecule is not affected. vir gene induction is temperature sensitive in an acetosyringone-independent virA mutant background but not in a virG constitutive mutant which is virA and acetosyringone independent. These observations all support the notion that the VirA protein is responsible for the thermosensitivity of vir gene expression. However, an Agrobacterium strain containing a constitutive virG locus still cannot cause tumors on Kalanchoe plants at 32 degrees C. This strain induces normal-size tumors at temperatures up to 30 degrees C, whereas the wild-type Agrobacterium strain produces almost no tumors at 30 degrees C. These results suggest that at temperatures above 32 degrees C, the plant becomes more resistant to infection by A. tumefaciens and/or functions of some other vir gene products are lost in spite of their normal levels of expression.

Agrobacterium tumefaciens↗
PubMed1993

Effects of adenosine A1 and A2 receptor activation on electrically evoked dopamine and acetylcholine release from rat striatal slices.

The authors investigated how electrically evoked [3H]dopamine (DA) and [14C]acetylcholine (ACh) release in the rat striatum is affected, directly or indirectly, by adenosine A1 and A2A receptor activation. Striatal slices, preincubated with [3H]DA and [14C] choline, were superfused continuously and subjected to electrical field stimulation. The electrically evoked release of both [3H] and [14C] was tetrodotoxin sensitive and calcium dependent. The release of both labels was augmented by haloperidol and sulpiride but only the [14C]ACh release was increased by 7-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol (each at 1 microM). The A1 receptor-selective agonist cyclohexyladenosine and the A2A receptor-selective agonist 2-[4-(2-carboxymethyl)-phenethylamino]-5'-N-ethylcarboxamido adenosine (CGS 21680) both caused a concentration-dependent (range, 0.01-1 microM) inhibition of electrically evoked DA and ACh release and with a surprisingly similar potency. The potency of both compounds, and particularly of cyclohexyladenosine, increased when they were allowed to equilibrate for a longer period with the slices. The effect of both compounds was blocked by the A1-selective antagonist 1,3-dipropyl-8-cyclopentyl xanthine (0.1 microM). CGS 21680 never caused any stimulation of DA or ACh release. The ability of the D2 agonist quinpirole to inhibit ACh release was reduced by CGS 21680 in the presence or absence of 0.1 microM 1,3-dipropyl-8-cyclopentyl xanthine. CGS 21680 did not alter the D2 receptor inhibition of DA release. In summary, adenosine analogs inhibit DA and ACh release from rat striatum by a receptor that may be different from those hitherto characterized.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Detection of the HPV16 E6 transforming gene by PCR in tissue samples from normal cervix and from cervix with precancerous lesions and carcinomas.

A study of 130 biopsies from cases of histologically confirmed normal cervix (30), cervicitis (28), cervical intraepithelial neoplasia (CINI-CIN III, 29), and cervical cancer (43) was performed to determine the presence of human papillomavirus (HPV) type 16 DNA sequences. The polymerase chain reaction technique was adopted using two oligonucleotides as primer pairs in the HPV16 early 6 (E6) gene open reading frame (ORF). The rates of HPV16 infection in normal tissues, cervicitis, CINI-CIN III and cervical cancer were found to be 16.67% (5/30), 25.00% (7/28), 41.38% (12/29) and 69.77% (30/43), respectively. Statistical analysis showed that the relative risk (RR) of association between HPV16 infection and the development of cervicitis, CINs and cervical carcinomas was increased with the severity of cervical lesions, from 1.0 (normal) to 1.67, 4.62 (P < 0.05; 95% CI 0.28-8.95) and 11.54 (P < 0.001; 95% CI 3.94-33.81), respectively. Our results strongly support the idea that the development of cervical precancerous lesions and cervical carcinomas is closely associated with HPV16 infection.

Adult↗
PubMed1992

A study on optimum load for physical work.

Five healthy men were chosen as experimental subjects and were divided into groups at random. The subjects walked with a load in a shoulder-waist-back manner on the treadmill at the speed of 5, 7 and 9 km h-1. The parameters measured were as follows: oxygen expenditure, energy consumption, heart rate and self appraisal. Based on the experimental results and analysis of multiple regression, the authors suggested that physical loading should not exceed 25 kg (i.e. roughly equal to 39% of average body weight of male Chinese), when the walking speed was at 5 km h-1. The suitable loading at physical work would be 20 kg (i.e. equal to 31% of the average body weight of male Chinese).

Adult↗