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Biomedical subjects

X Jia

Publications and source records attributed to X Jia.

At least 91 records · Page 5Linked to original sources
PubMed1997

[Immunohistochemical study on the distribution and coexistence of SP, VIP and NPY in the rat submandibular gland].

The distribution and coexistence of SP, VIP and NPY in the submandibur gland of rat have been studied with immunohistochemical ABC methods. The results indicated that SP, VIP and NPY-IR nerve fibers were presented as varicose and linear profiles, which mainly travelled around acini, duct and blood vessels. The ganglion cells in submandibular gland showed SP, VIP and NPY-IR all positive immunocytochemically. The findings indicated that the neuropeptides were coexisted in the same neuron body and might play the role of regulation of the secretary activity and effective blood supply.

Animals↗
PubMed1997

[The etiologic role of thermal injury on the induction of NO and NOS in plasma, burned wounds and visceral organs].

Using a 35% TBSA burned animal moedl, we investigated the levels of NO contents (nitritc concentration assay) and NOS (hemoglobulin absorbent optical density test) in the burned wound, circulation, as well as five visceral organs which inluded heart, lung, liver, kidney and intestine mucosa. Samples were obtained from scalded male Wistar rats at 1 hour postburn (PBh1)PBh3, PBh8, PBh12, PBh24, PBh48 and PBh72, respectively. Samples of sham burned rats were obtained as controls. The plasma level of NO concentration was decreased within 72 hours postburn especially at PBh3, 8, 12, 24, 48 (P < 0.05 to P < 0.01). This was in agreement with our findings in the ESR assay. The cutaneous NO cotents was 3.8 to 57.8 times higher than that of plasma and other visceral organs. It is thus possible for burned skin tissue to be an important sites in the production of NO. However, the cutaneous NO might have little systemic influences and can only be a local fator due to its short half-life. The close relationship of changes in the NO and NOS in five visceral organs postburn provided strong evidence on the function of NOS as NO premerase.

Animals↗
PubMed1997

[Study on the coagulant activity of human blood monocytes].

OBJECTIVE: To investigate the coagulant and fibrinolytic activities of human blood monocytes. METHODS: Cultured monocytes (2. 8 x 10(6) cells) were refrigerated at -20 degrees C and then thawed and centrifuged. Blood coagulant factors activities in the upper and lower layer of the supernatant were assayed and compared with that in the supernatant of white blood cells (containing 2. 8 x 10(6) cells). RESULTS: There were factors II , VII, IX, X, V, and tissue factor activities in the supernatant, X III A : Ag was 2.1%, X III S : Ag : 2.8%, while t-PA : A and PAI : A were undetectable. In the lower layer there was no specific expression of blood coagulant factors. CONCLUSION: There were coagulant activities in the supernatant containing the membrane and cytoplasma of monocytes.

Blood Coagulation↗
PubMed1996

Structure of the Bacillus subtilis phage SPO1-encoded type II DNA-binding protein TF1 in solution.

The solution structure of a type II DNA-binding protein, the bacteriophage SPO1-encoded transcription factor 1 (TF1), was determined using NMR spectroscopy. Selective 2H-labeling, 13C-labeling and isotopic heterodimers were used to distinguish contacts between and within monomers of the dimeric protein. A total of 1914 distance and dihedral angle constraints derived from NMR experiments were used in structure calculations using restrained molecular dynamics and simulated annealing protocols. The ensemble of 30 calculated structures has a root-mean-square deviation (r.m.s.d.) of 0.9 A, about the average structure for the backbone atoms, and 1.2 A for all heavy-atoms of the dimeric core (helices 1 and 2) and the beta-sheets. A severe helix distortion at residues 92-93 in the middle of helix 3 is associated with r.m.s.d. of approximately 1.5 A for the helix 3 backbone. Deviations of approximately 5 A or larger are noted for the very flexible beta-ribbon arms that constitute part of a proposed DNA-binding region. A structural model of TF1 has been calculated based on the previously reported crystal structure of the homologous HU protein and this model was used as the starting structure for calculations. A comparison between the calculated average solution structure of TF1 and a solution structure of HU indicates a similarity in the dimeric core (excluding the nine amino acid residue tail) with pairwise deviations of 2 to 3 A. The largest deviations between the average structure and the HU solution structure were found in the beta-ribbon arms, as expected. A 4 A deviation is found at residue 15 of TF1 which is in a loop connecting two helical segments; it has been reported that substitution of Glu15 by Gly increases the thermostability of TF1. The homology between TF1 and other proteins of this family leads us to anticipate similar tertiary structures.

Bacillus subtilis↗
PubMed1996

1H NMR studies of the 5-(hydroxymethyl)-2'-deoxyuridine containing TF1 binding site.

The pyrimidine base 5-(hydroxymethyl)-2'-deoxyuridine (HmU) is a common nucleotide in SPO1 phage DNA. Numerous transcriptional proteins bind HmU-containing DNA preferentially implicating a regulatory function of HmU. We have investigated the conformation and dynamics of d-(5'-CHmUCHmUACACGHmUGHmUAGAG-OH-3')2 (HmU-DNA). This oligonucleotide mimics the consensus sequence of Transcription Factor 1 (TF1). The HmU-DNA was compared to the thymine-containing oligonucleotide. NOESY and DQF COSY spectroscopy provided resonance assignments of nonexchangeable and exchangeable protons, intranucleotide, internucleotide and intrastrand proton-proton distances, and dihedral angle constraints. Methylene protons of the hydroxymethyl group are nonequivalent protons and the hydroxymethyl group is not freely rotating. The hydroxymethyl group adopts a specific orientation with the OH group oriented on the 3' side of the plane of the base. Analysis of imino proton resonances and NOEs indicates additional end base pair fraying and a temperature-induced transition to a conformation in which the internal HmU-A base pairs are disrupted or have reduced lifetimes. Orientation of the hydroxymethyl group indicates the presence of internucleotide intrastrand hydrogen bonding between the HmU12C5 hydroxyl group and A13. All sugars in both DNAs show a C2'endo conformation (typical of B-DNA).

Base Sequence↗
PubMed1996

DNA-binding determinants of the alpha subunit of RNA polymerase: novel DNA-binding domain architecture.

The Escherichia coli RNA polymerase alpha-subunit binds through its carboxy-terminal domain (alpha CTD) to a recognition element, the upstream (UP) element, in certain promoters. We used genetic and biochemical techniques to identify the residues in alpha CTD important for UP-element-dependent transcription and DNA binding. These residues occur in two regions of alpha CTD, close to but distinct from, residues important for interactions with certain transcription activators. We used NMR spectroscopy to determine the secondary structure of alpha CTD, alpha CTD contains a nonstandard helix followed by four alpha-helices. The two regions of alpha CTD important for DNA binding correspond to the first alpha-helix and the loop between the third and fourth alpha-helices. The alpha CTD DNA-binding domain architecture is unlike any DNA-binding architecture identified to date, and we propose that alpha CTD has a novel mode of interaction with DNA. Our results suggest models for alpha CTD-DNA and alpha CTD-DNA-activator interactions during transcription initiation.

Amino Acid Sequence↗
PubMed1996

Schistosoma mansoni: protective immunity in IL-4-deficient mice.

Vaccination of mice with radiation-attenuated Schistosoma mansoni larvae (cercariae) either once or multiple times produces similar levels of resistance to subsequent infection, but by different immunological mechanisms. In singly immunized mice, protection is CD4+ cell mediated and IFN-gamma dependent. Resistance in multiply immunized mice is humorally mediated (especially the IgG1 isotype), suggesting a key role of Th2-associated cytokine responses. Since IL-4 has been shown to regulate Th2 development, animals in which the IL-4 gene has been knocked out by homologous recombination (IL-4 -/-) or wild-type mice (IL-4 +/+) were immunized three times with attenuated cercariae and challenged with normal cercariae. In three separate experiments the percentage of reduction of adult worms in immunized compared to unimmunized IL-4 +/+ animals (68 to 82%) was equivalent to IL-4 -/- (52 to 66%), although protection tended to be lower in each experiment. Serum levels of adult worm (SWAP)-specific IgG2a and IgG2b were 10- and 2-fold higher in IL-4 -/- mice while IgA levels were equivalent between the two groups. Serum levels of SWAP-specific IgG1 were slightly lower in IL-4 -/- mice (P = 0.07) compared to wild-type animals and inversely correlated with worm burdens (r = -0.65, P = 0.02), suggesting that the slightly diminished IgG1 accounts for the tendency toward lower worm burdens in IL-4 -/- animals. No relationships between worm numbers and the other isotypes were observed. SWAP-induced IL-5 production by splenocytes from IL-4 -/- animals were 6-fold lower, although present, compared to IL-4 +/+ mice while Ag-induced IFN-gamma production was increased by over 4-fold. These results demonstrate that IL-4 is not essential for development of protective immunity in mice multiply vaccinated with irradiated cercariae and that compensatory or alternative pathways exist to generate a Th2-associated response. The limitations of mice with targeted gene deletions in delineating the role of specific cytokines in regulating the immune response to complex infections like schistosomiasis are emphasized.

Animals↗
PubMed1996

Errors in time in pharmacokinetic studies.

Pharmacokinetic models with errors in the time variable were developed and explored by simulation in NONMEM. The precision of estimated parameters decreased with increasing error magnitude. The usual asymptotic standard error estimates were biased low by 10-50%. Accuracy and precision were not greatly diminished by ignoring errors in time when fitting models.

Computer Simulation↗
PubMed1996

[Relationship between particle fluence and dose in cabin of recoverable satellite].

Radiation doses in the cabin of the recoverable satellite measured by GJ-III personal dosimeters and LiF thermoluminescent dosimeters were presented. The relationship between the particle fluence calculated from instrument display and the measured doses was studied. It shows that the particle fluence can be directly calculated from the measured dose with a transformation coefficient which is not obviously affected by shielding around the measuring site. The estimated average energy of the particles in the cabin is on the level of Galactic cosmic radiation.

Cosmic Radiation↗
PubMed1996

[Immune and biochemical analysis of protein of homogenates of three different kinds of skin].

The amount and constitution of protein, its ultraviolet photo-absorption ability, and esterase in homogenates of human cadaveric and guinea pig skin (each consisted of newborn, fresh adult and stored adult skin) were assayed by using ultraviolet spectrophotometer, polyacrylamide gel electrophoresis and sodium dodecyl sulphate polyacrylamide gel electrophoresis. Our experiment shows that immune and biochemical analysis of protein of three different skin groups are different. The biochemical components of cadaveric and guinea pig skin protein and esterase in newborn skin group are lowest. The changes in adult skin stored at -196 degrees C are less obvious as compared with that in fresh adult skin.

Animals↗
PubMed1996

Study on serum-free media for genetically engineered CHO cells producing prourokinase.

Based on the initial optimization of DMEM:F12(1:1), two kinds of serum-free media, 11G-SG-SFM and 11G-SE-SFM, were formulated by using orthogonal experiments for the growth of genetically engineered CHO cell line 11G and the production of recombinant prourokinase (pro-UK) in a suspension culture, respectively. Growth of 11G cells in 11G-SG-SFM was comparable with that observed in DMEM:F12 + 5% NBS and CHO-S-SFM. 11G cells grew slowly in 11G-SE-SFM, but secreted a relatively high level of pro-UK. The pro-UK productivity of 11G cells in 11G cells in 11G-SE-SFM reached 800 to 1,000 IU/10(6). d-1 and was about 80% and 20% higher than in DMEM:F12 + 5% NBS and CHO-S-SFM, respectively.

Animals↗
PubMed1996

[Measurement of blood NO contents using ESR method in rats after thermal injury].

The contents of nitric oxide (NO) in the blood were measured by electron spin resonance (ESR) method in Wistar rats with 35% TBSA III degrees burn. NO is endothelium derived relaxing factor (E-DRF) released by vascular endothelial cells. The results showed that: 1. Blood NO contents were not found to be significantly increased (72 hours postburn); 2. Escherichia coli lipopolysaccharide (LPS, endotoxin) could induce excessive NO formation in early burns.

Animals↗
PubMed1996

[The changes in TNF alpha in plasma, organs and eschar of rats after thermal injury].

The TNF alpha (Tumor Necrosis Factor-alpha) contents in the plasma, five organs (heart, lung, liver, kidney and intestine) and burned skin were measured by ELISA method in Wistar rats with 35% TBSA III degrees. The animals were divided into eight different time groups. The experiment showed that TNF alpha contents were excessively high in early stage of burn (24 hours postburn) in plasma, eschar and the five organs. The contents of TNF alpha in eschar were 27.5-86.7 times higher than that in plasma and the five organs.

Animals↗
PubMed1996

[An investigation of a family tree with congenital deficiency in coagulation factor XIII].

In order to study the hereditary trait of a 20-year-old girl with congenital deficiency of coagulation factor XIII and her family tree, the following laboratory tests were done for the propositus and her family members: clot solubility test in 5 mol/L urea, estimation of factor XIII activity, amount of the subunits A and S of factor XIII with rocket electrophoresis. The results showed that the propositus had clinical history of bleeding in umbilical cord and its stump after birth. Her parents are not consanguineously related and have no history suggestive of hemorrhagic diathesis. The propositus has one brother and three sisters. One of her sisters died of bleeding of the umbilical cord after birth, another died at age of two, but the reason of her death is unclear and the remaining siblings are clinically healthy. The propositus had an abnormal urea clot lysis test, but the other family members had normal results. For the propositus factor XIII activity was 0%. A subunit 0% and S subunit 8.2%. Factor XIII activity of her father, her mother and her sister were 25%, 50%, 25% respectively. A subunit 52%, 58%, and 58% respectively and S subunit 66%, 68% and 66% respectively. The results showed that the propositus has a congenital deficiency in coagulation factor XIII, and her parents and sister are in fact carriers.

Adult↗
PubMed1995

Multidimensional NMR spectroscopy of DNA-binding proteins: structure and function of a transcription factor.

The solution structure of a type II DNA-binding protein (DBPII), transcription factor 1 (TF1), has been determined using NMR spectroscopy. A multidimensional, heteronuclear strategy was employed to overcome assignment ambiguities due to resonance overlap and broadened crosspeaks. This approach involved the use of selectively deuteriated, 13C- and 15N-labeled samples and 'isotopic heterodimers' to distinguish between intra- and intermonomeric NOEs. A comparison with the crystal structure and NMR analysis of the E. coli HU protein suggests that other homologous proteins in this family will possess similar tertiary structures. This NMR strategy is applicable to the study of other proteins and their biomolecular complexes.

Amino Acid Sequence↗
PubMed1995

Effects of glucose-dependent insulinotropic polypeptide and glucagon-like peptide-I-(7-36) on insulin secretion.

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP)-I-(7-36) are probably the most important "incretins," but there is controversy as to their relative insulinotropic activities. The effects of natural (np) and synthetic porcine (sp) GIP, synthetic human (sh) GIP, and GLP-I-(7-36) on insulin secretion from the perfused rat pancreas were compared using gradient perfusion. Insulin secretion was increased by both spGIP and GLP-I-(7-36) at concentrations of approximately 16 pM. Maximal responses to GLP-I-(7-36) in the presence of 16.7 mM glucose were slightly greater than with npGIP or spGIP, but with 10 mM glucose spGIP and GLP-I-(7-36) exerted equivalent effects. Responses to shGIP were greatly reduced compared with spGIP. In the presence of 50 pM spGIP or GLP-I-(7-36) the glucose threshold was 4.5 +/- 0.11 mM. The data indicate that GLP-I-(7-36) and porcine GIP are equally insulinotropic and share the same glucose threshold for activity, whereas shGIP is less active. At the concentrations found postprandially, however, GIP is likely to be the more important incretin.

Animals↗
PubMed1995

Altered glucose dependence of glucagon-like peptide I(7-36)-induced insulin secretion from the Zucker (fa/fa) rat pancreas.

In previous studies on the enteroinsular axis in Zucker rats, it was found that glucose-dependent insulinotropic polypeptide (GIP) levels were normal in obese animals, but the glucose threshold for the insulinotropic action of GIP in the perfused rat pancreas was reduced. Glucagon-like peptide I (GLP-I)(7-36) is also an important incretin, and in the current study, glucose, insulin, and immunoreactive (IR)-COOH-terminal GLP-I responses to oral glucose were compared in lean (Fa/?) and obese (fa/fa) rats. In addition, the concentration thresholds for stimulation and glucose dependence of perfused pancreases to GLP-I(7-36) were examined. Glucose responses to oral glucose were similar in fa/fa and Fa/? rats. Obese animals were hyperinsulinemic when fasting and after oral glucose. Significant increases in IR-GLP-I levels in response to glucose were only observed in fa/fa rats. Perfused pancreases from fa/fa rats hypersecreted insulin at all glucose concentrations. In the presence of 4.4 mmol/l glucose, GLP-I(7-36) increased insulin secretion in fa/fa pancreases approximately 25-fold, whereas there was only a 5-fold increase in Fa/? pancreases. Pancreases from fa/fa rats, perfused with a glucose gradient (2.8-11 mmol/l) in the presence of GLP-I(7-36), responded with an immediate increase in insulin secretion, i.e., at a glucose concentration of 2.8 mmol/l, whereas Fa/? pancreases required a minimum of 4.22 mmol/l glucose for stimulation. With high glucose (16.7 mmol/l), both fa/fa and Fa/? rat pancreases exhibited similar responsiveness to GLP-I(7-36), having thresholds of < 50 pmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗