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Biomedical subjects

H Jiang

Publications and source records attributed to H Jiang.

At least 487 records · Page 27Linked to original sources
PubMed1996

Rapid purification of the oxygenase component of toluene dioxygenase from a polyol-responsive monoclonal antibody.

A monoclonal antibody designated 302 beta that is specific for the beta subunit of the oxygenase component (ISPTOL) of toluene dioxygenase from Pseudomonas putida F1 was used to prepare an immunoaffinity column. ISPTOL in cell extracts of Escherichia coli JM109(pDTG611) bound to the column, and an enzyme-linked immunosorbent elution-screening assay with different combinations of polyols and kosmotropic anions was used to determine the conditions necessary for recovery of active enzyme. Elution from an 8-ml antibody column with 50 mM 2-(N-morpholino)ethanesulfonate buffer (pH 6.8) containing 50% ethylene glycol, 1.0 M ammonium sulfate, 1.0 mM dithiothreitol, and 0.2 mM ferrous ammonium sulfate gave approximately 2 mg of ISPTOL with a specific activity that was more than 300 times the specific activity previously obtained.

Animals↗
PubMed1996

Site-directed mutagenesis of conserved amino acids in the alpha subunit of toluene dioxygenase: potential mononuclear non-heme iron coordination sites.

The terminal oxygenase component of toluene dioxygenase from Pseudomonas putida F1 is an iron-sulfur protein (ISP(TOL)) that requires mononuclear iron for enzyme activity. Alignment of all available predicted amino acid sequences for the large (alpha) subunits of terminal oxygenases showed a conserved cluster of potential mononuclear iron-binding residues. These were between amino acids 210 and 230 in the alpha subunit (TodC1) of ISP(TOL). The conserved amino acids, Glu-214, Asp-219, Tyr-221, His-222, and His-228, were each independently replaced with an alanine residue by site-directed mutagenesis. Tyr-266 in TodC1, which has been suggested as an iron ligand, was treated in an identical manner. To assay toluene dioxygenase activity in the presence of TodC1 and its mutant forms, conditions for the reconstitution of wild-type ISP(TOL) activity from TodC1 and purified TodC2 (beta subunit) were developed and optimized. A mutation at Glu-214, Asp-219, His-222, or His-228 completely abolished toluene dioxygenase activity. TodC1 with an alanine substitution at either Tyr-221 or Tyr-266 retained partial enzyme activity (42 and 12%, respectively). In experiments with [14C]toluene, the two Tyr-->Ala mutations caused a reduction in the amount of Cis-[14C]-toluene dihydrodiol formed, whereas a mutation at Glu-214, Asp-219, His-222, or His-228 eliminated cis-toluene dihydrodiol formation. The expression level of all of the mutated TWO proteins was equivalent to that of wild-type TodC1 as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analyses. These results, in conjunction with the predicted amino acid sequences of 22 oxygenase components, suggest that the conserved motif Glu-X3-4,-Asp-X2-His-X4-5-His is critical for catalytic function and the glutamate, aspartate, and histidine residues may act as mononuclear iron ligands at the site of oxygen activation.

Amino Acid Sequence↗
PubMed1996

Characterization of the glucose-induced inactivation of maltose permease in Saccharomyces cerevisiae.

The addition of glucose to maltose-fermenting Saccharomyces cerevisiae cells causes a rapid and irreversible loss of the ability to transport maltose, resulting both from the repression of transcription of the maltose permease gene and from the inactivation of maltose permease. The latter is referred to as glucose-induced inactivation or catabolite inactivation. We describe an analysis of this process in a maltose-fermenting strain expressing a hemagglutinin (HA)-tagged allele of MAL61, encoding maltose permease. The transfer of maltose-induced cells expressing the Mal61/HA protein to rich medium containing glucose produces a decrease in maltose transport rates which is paralleled by a decrease in Mal61/HA maltose permease protein levels. In nitrogen starvation medium, glucose produces a biphasic inactivation, i.e., an initial, rapid loss in transport activity (inhibition) followed by a slower decrease in transport activity, which correlates with a decrease in the amount of maltose permease protein (proteolysis). The inactivation in both rich and nitrogen-starved media results from a decrease in Vmax with no apparent change in Km. Using strains carrying mutations in END3, REN1(VPS2), PEP4, and PRE1 PRE2, we demonstrate that the proteolysis of Mal61/HAp is dependent on endocytosis and vacuolar proteolysis and is independent of the proteosome. Moreover, we show that the Mal61/HA maltose permease is present in differentially phosphorylated forms.

Biological Transport↗
PubMed1996

Increased myosin light chain kinase content in sensitized canine saphenous vein.

Our previous studies revealed that smooth muscle from sensitized canine saphenous vein (SCSV) demonstrated greater active shortening capacity, maximum shortening velocity, and prolonged relaxation vis-a-vis the control muscle. These changes could be responsible for the in vivo hyperreactivity of venous smooth muscle observed in anaphylactic shock. Because smooth muscle cross-bridge cycling is regulated by myosin light chain kinase (MLCK)-dependent phosphorylation of the 20-kDa myosin light chain (MLC20), we studied MLC20 and MLCK phosphorylation in homogenates of SCSV and veins from littermate control dogs. We found that phosphorylation of MLC20 in SCSV homogenate was higher (42.26 +/- 5.10%) compared with control homogenates (26.69 +/- 3.30%; P < 0.05); MLCK content was significantly higher in SCSV homogenates [0.169 +/- 0.019 (SE) mu g/mg protein] than in control homogenates (0.075 +/- 0.004 mu g/mg protein; P < 0.05). Total MLCK activity increased from 6.16 +/- 0.60 x 10(-5) nmol Pi x mg fresh weight of tissue-1 x min-1 in control homogenates to 12.50 +/- 2.50 x 10(-5) nmol Pi x mg fresh weight of tissue-1 x min-1 in sensitized homogenates (P < 0.05). Specific MLCK activity was, however, similar in sensitized and control homogenates. The results of our study suggest that elevation of MLCK content in the homogenate could account for the increased contractility of the SCSV in anaphylactic shock.

Animals↗
PubMed1996

Inhibitory effect of TMK688 on skin tumor initiation caused by 7,12-dimethylbenz[a]anthracene in relation to inhibition of aryl hydrocarbon hydroxylase activity and Cyp1a1 mRNA induction.

Oral administration of TMK688 (1-([5'-(3"-methoxy-4"-ethoxycarbonyloxyphenyl)-2',4'-pentadien oyl] aminoethyl)-4-diphenylmethoxypiperidine: 30 mg/kg) at 6 h and 30 min prior to and at 30 min after a single topical application of 7,12-dimethylbenz[a]anthracene (DMBA) to dorsal skins of mice reduced both tumor incidence and number of tumors per mouse in the DMBA-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted two-stage mouse skin carcinogenesis. TMK688 and its active metabolite TMK777 (1-([5'-(3"-methoxy-4"- hydroxyphenyl)-2',4'-pentadienoyl]-aminoethyl)-4-diphenylmethox y piperidine) inhibited 3-methylchol-anthrene (MC)-induced epidermal aryl hydrocarbon hydroxylase (AHH) activity in a concentration-dependent manner. IC50 of TMK688 and TMK777 was 0.18 and 0.01 mumol/l, respectively. Oral administration of TMK688 (30 mg/kg) almost completely suppressed Cyp1a1 mRNA levels in mouse epidermis induced by a topical application of MC (40 mg/kg) or benzo[a]pyrene (200 nmol) to mouse skin. Oral administration of TMK688 (30 mg/kg) also almost completely inhibited induction of epidermal AHH activity caused by a topical application of MC. These results indicate that oral administration of TMK688 inhibited DMBA-caused skin tumor initiation at least in part by inhibiting Cyp1a1 mRNA induction and epidermal AHH activity.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Molecular weights and isoelectric points of sperm antigens relevant to autoimmune infertility in men.

PURPOSE: We determined the molecular weights and isoelectric points of antigens in the uncapacitated and capacitated spermatozoa of fertile men binding to the serum immunoglobulin G (IgG) from 8 autoimmune infertile men and 8 fertile nonautoimmune men. MATERIALS AND METHODS: We used double fluorochrome cytotoxicity and immunobead binding assays to determine the sperm antibody status of the study subjects. 2-Dimensional gel electrophoresis and Western blot analysis were used to determine the molecular weights and isoelectric points of sperm antigens binding to serum IgG from these men. Amino acid sequencing of the digested peptides of chosen proteins was accomplished. Immune reactivity to the proteins in autoimmune infertile men was further verified. RESULTS: Serum IgG from fertile men failed to react significantly. Serum IgG from all autoimmune men (100%) showed significant binding to proteins with a molecular weight of 92 kDa. and isoelectric points of 3.5 to 4.0 in the capacitated spermatozoa. Six of 8 infertile men (75%) had serum IgG binding to capacitated sperm antigens with a molecular weight of 18 kDa. and isoelectric points of 4.5 to 5.2. Amino acid sequencing of peptides of the 92 kDa. protein matched complement component 1 (C1) inhibitor, with noted differences in the amino acid sequencing from the latter. The 18 kDa. protein matched calmodulin. We verified that serum IgG from autoimmune infertile men bound with C1 inhibitor and ascertained that the 92 kDa. protein in the spermatozoa was C1 inhibitor-like protein. CONCLUSIONS: Significant antibody responses to C1 inhibitor-like protein and calmodulin were noted in autoimmune men. Both of these proteins may be of testicular origin and these autoimmune responses may be highly relevant to infertility.

Amino Acid Sequence↗
PubMed1996

Functional magnetic resonance imaging for intracranial navigation.

Functional MR imaging can provide accurate anatomic and physiologic localization of human cortical function. This new method of noninvasive cortical mapping appears to be valuable preoperatively for risk assessment, therapeutic decision making and surgical planning. The integrated volume rendering of brain surface topography, cortical veins, structural lesion, and sites of functional activation is also useful intraoperatively for defining cortical resection boundaries in patients with lesions in critical areas.

Adolescent↗
PubMed1996

In situ amplification of DNA fragments specific for human Y chromosome in cellular nuclei by PCR.

Using single primer pairs Y3 and Y4 in situ polymerase chain reaction (in situ PCR) was successfully performed on the specimen slides of peripheral leukocytes. By both of the direct digoxiginin-11-dUTP incorporation into PCR products with in situ PCR (direct in situ PCR) and in situ PCR followed by detection of in situ hybridization (indirect in situ PCR), DNA fragments specific for human Y chromosome were obviously amplified in cellular nuclei of specimens on the slides. The results were verified by Southern analysis. The methodology of in situ PCR and its application were discussed.

Cell Nucleus↗
PubMed1996

The spatiotemporal development of innervation in spinal ligaments of chickens.

The development of the innervation of both central and lateral (intertransverse) spinal ligaments was investigated in chickens between the time of hatching and 13 wk of age. A total of 36 White Leghorn chickens in 4 groups of 9 at ages 0, 2, 7, and 13 wk were used. The spinal ligaments were dissected, serially sectioned and labelled with a monoclonal antibody against neurofilament protein and observed using either conventional fluorescence or confocal microscopy. Only a few nerve elements were found in the ligaments at hatching and these consisted simply of single nerve fibres and small nerve bundles. The number of nerve elements increased rapidly up to 7 wk of age when large nerve bundles and Ruffini corpuscles were also found. The number of nerve elements decreased between 7 and 13 wk birds when the ligaments had begun to ossify and the amount of collagenous ligamentous tissue was significantly reduced. The fluctuation in numbers of neural elements was due to changes in numbers of single nerve fibres and small nerve bundles rather than large nerve bundles and Ruffini corpuscles which remained constant. In contrast to this significant increase in numbers of nerve elements, the innervation density of the ligaments decreased because of the overwhelming increase of the ligament volume due to growth. There were no differences between ligaments on the left and right sides of the body, but there was an unequal distribution of the neural elements within the ligaments; most were found in the cranial third of the intertransverse ligaments. These results show that significant changes in innervation of spinal ligaments occur during development and reflect the possibility that damage to the ligaments during this time could produce significant and permanent damage, especially in relation to the maintenance of an erect spine.

Animals↗
PubMed1996

Low rates of apoB secretion from HepG2 cells result from reduced delivery of newly synthesized triglyceride to a "secretion-coupled" pool.

The present study was aimed at defining the roles of intracellular triglyceride pools in apolipoprotein B secretion from HepG2 cells. Oleic acid (0.2 mmol/L) in the medium stimulated both triglyceride synthesis and apolipoprotein B secretion. Stimulation of apolipoprotein B secretion was lost about 30-40 min after oleic acid was removed from the medium, despite the finding that most newly synthesized triglyceride was still present in the cells. This suggested that only a small fraction of newly synthesized triglyceride was transferred to a pool available for assembly of nascent apoB into lipoproteins. Using cell fractionation, we analyzed two triglyceride pools in HepG2 cells: a microsomal pool and a cytoplasmic pool. Oleic acid-induced increases in the microsomal pool were small and short-lived due to secretion; this pool, therefore, is a "secretion-coupled" pool. The large majority of newly synthesized triglyceride was in a cytosolic pool that was not associated with secretion of apoB. Dibutyryl cAMP treatment was associated with a 3-fold increase in the mobilization of the triglyceride droplets. Apolipoprotein B secretion, however, was not increased, suggesting that the amount of triglyceride that entered the "secretion-coupled" pool after hydrolysis and re-esterification of cytoplasmic triglyceride was inadequate to stimulate apolipoprotein B secretion. In summary, the majority of newly synthesized triglyceride, whether derived from exogenous or endogenous fatty acids, is rapidly shifted to a cytoplasmic pool that does not play a regulatory role in apolipoprotein B secretion. The presence of a very small "secretion-coupled" pool of triglyceride in HepG2 cells likely explains the high rates of degradation of nascent apolipoprotein B, and the low rates of secretion of lipid-poor lipoproteins.

Apolipoproteins B↗
PubMed1996

Mutagen sensitivity as a marker of cancer susceptibility.

Modulation of environmental exposures by host genetic factors may explain interindividual variation in susceptibility to carcinogenesis. One determinant of susceptibility is mutagen sensitivity measured by the frequency of bleomycin-induced breaks in an in vitro lymphocyte assay. Mutagen sensitivity is a significant predictor of aerodigestive tract cancer risk. In this case-control study of lung-cancer susceptibility markers, 54% of 132 lung-cancer cases had mutagen-sensitivity scores greater than or equal to 1 break/cell, compared with only 22% of 232 controls. The mean breaks/cell value (+/-SE) for the 88 African-American cases was 1.11 (+/-0.60), compared with 0.82 (+/-0.49) for the 121 controls (P < 0.001). For the 44 Mexican-American cases and 111 controls, the comparable values were 1.11 (+/-0.52) and 0.76 (+/-0.38), respectively. The overall odds ratio (OR) for mutagen sensitivity (dichotomized at > or = 1 break/cell), after adjusting for ethnicity and smoking status, was 3.62 (95% confidence limits [CL] = 2.2, 5.9). For current smokers the adjusted risk associated with mutagen sensitivity was 2.52 (1.2, 5.3). For former smokers, the comparable OR (95% CL) was 6.19 (2.7, 14.1). The risk estimate for those under 61 years of age was 4.85 (2.3, 10.4), compared with 2.85 (1.5, 5.6) for older subjects. The risk also appeared to be higher for lighter smokers (< 20 cigarettes daily) than heavier smokers (ORs = 5.72 and 3.20, respectively). The ethnicity-adjusted ORs by quartile of breaks/cell were 1.0, 1.40, 2.46, and 4.80; the trend test was significant at P < 0.001. The joint effects of mutagen sensitivity and former smoking, current smoking, or heavy smoking were greater than additive, although the interaction terms were not statistically significant in the logistic model. Mutagen sensitivity may therefore be a useful member of a panel of susceptibility markers for defining high-risk subgroups for chemoprevention trials.

Adult↗
PubMed1996

[Effects of electret and Ligusticum wallichii (chuangxiong) on the functional recovery of muscle grafts].

The aim of this study was to evaluate the effects of electret and Ligusticum wallichii (Chuangxiong, a traditional Chinese herb medicine) on the functional recovery of muscle grafts. Twenty-eight adult dogs were divided into 4 groups with each consisting of 7 animals. After orthotopical transplantation of bilateral rectus femoris muscle with neurovascular anastomosis, group A received electret local implant, group B received Chuangxiong injection, group C received both electret local implant and Chuangxiong injection and group D was used as control. The results showed that the functional recovery of the transplanted rectus femoris muscle in group A and B was better than group D while group C was the best. At 22 postoperative weeks, the recovery rate of maximal tetanic tension was 64.94 +/- 3.82% in group c: 57.68 +/- 1.67% in group A, 53.64 +/- 3.82% in group B and 47.99 +/- 2.21% in group D (P < 0.05). The structural recovery of the transplanted muscle in group C was closest to the normal.

Action Potentials↗
PubMed1996

[Study of heterogeneity in DNA ploidy and its clinical-pathological significance in esophageal squamous cell carcinoma].

In order to investigate the intratumoral DNA ploid heterogeneity in esophageal squamous cell carcinoma and its significance, nuclear DNA ploidy of 80 cases of squamous cell carcinoma of the esophagus were determined for multiple samples obtained from the same tumor, using a flow cytometry (FCM) technique. The results showed that: (1) DNA indeces ranged from 7.7-1.74, and the incidence of DNA aneuploidy was 88.8% (71/80) in this series; (2) of 80 cases, (47.5% 38 cases) showed intratumoral heterogeneity in DNA ploidy (3) the heterogeneity in DNA ploidy was related to the extent of wall penetration by tumor, the incidnce of lymph node metastasis and patient's prognosis, not to histological grades and size of tumor. The results from this study indicated that DNA ploidy heterogeneity may be a exact indicator in reflecting the biological characteristics of tumor and patient's prognosis than DNA aneuploidy from single site sampling.

Adult↗
PubMed1996

[Molecular weight determination and protein analysis of GCF-5 antigens of giant cell tumor of bone].

In order to understand the tumor antigen(s) of giant cell tumor of bone (GCT), monoclonal antibody GCF-5 developed in this laboratory was employed. GCF-5 reacted specifically against the tumor cell associated antigens of GCT. The membrane proteins of tumor cell were extracted by high concentration of SDS, followed by a series of treatment processes, including SDS-PAGE, western blotting and some staining methods, such as Periodic-Schiff for glycoprotein and oil red O for lipoprotein. The molecular weight and chemical characteristics of GCF-5 antigens were analysed. The preliminary results indicated that the main GCF-5 antigens were two glycoproteinis containing few saccharide chains, one of which was 13.5KD and the other 17.4KD.

Antigens, Neoplasm↗
PubMed1996

239 cases of high fever in viral upper respiratory infection (URI) treated with xiang shi qing jie (XSQJ) bag tea.

XSQJ bag tea was used to treat 239 cases of high fever caused by viral upper respiratory infection, widely spreading in summer and autumn. For comparison, a control group treated by penicillin combined with Ganmao Qingre Chongji or Banlangen Chongji was set up. The results showed the effect of XSQJ bag tea on the time of abating fever, resolving symptoms and physical signs were significantly better than that of the control group.

Adenovirus Infections, Human↗
PubMed1996

[Cyclin-dependent kinase inhibitors in mammal cells].

In recent two years, a group of protein factors have been found to combine with the cyclin-dependent kinases (CDKs) and block the activation of cyclin/CDK complexes. They are named CDK inhibitors (CKIs) as p21, p16, p15, p27 and CDI1. The p21 and p27 have certain homology and can inhibit the activity of multiple CDKs; p16 and p15 have higher homology and can specifically combine with CDK4 and CDK6; and the combination specificity of CDI1 needs further research. The expression of p21 is regulated positively by p53. TGF-beta can upregulate the expression of p15 and the inhibitory activity of p27. The above findings demonstrate that CKIs are not only the regulators of CDKs' activity but also the direct linkers between cancer inhibitors and cell-cycle regulation.

Animals↗
PubMed1996

[Effect of epidermal growth factor and dexamethasone on blast hearing loss].

The expression of epidermal growth factor receptor (EGFR) in cochlear hear cells was studied in normal and guinea pigs exposed to blasts. The effects of epidermal growth factor (EGF) and dexamethasone (DXM) treatment for blast hearing loss and the underlying mechanisms were also explored. Scattered expression of EGFR was seen in IHCs and OHCs in normal guinea pigs. Segmentally distributing positive reaction was also located in stereocillia of hair cells. Distribution of EGFR reaction was seen in the cytoplasm of IHC 24 hours after exposure to blasts, and in the stereocillia of IHC and the cuticular plate of OHC 72 hours postexposure. At one week EGFR reaction in hair cells increased obviously and part of OHC stereocillia also showed positive reaction. EGFR reaction reduced at two weeks, though positive reaction could still be found in the stereocillia of hair cells at one month. Combination of EGF and DXM administrations promoted hearing recovery significantly. Our results suggest that healing of injured hair cells may be to EGF.

Animals↗