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Biomedical subjects

W Jiang

Publications and source records attributed to W Jiang.

At least 235 records · Page 13Linked to original sources
PubMed1997

Aquaporin-2 in the immature rat: expression, regulation, and trafficking.

The immature kidney is resistant to arginine vasopressin. To define the role of aquaporin-2 (AQP-2), the developmental expression of this water channel was studied in rats. AQP-2 levels were lower during early postnatal life, reaching maximal expression at 10 wk of age. Concurrently, urine osmolality increased from 242 +/- 60 to 1267 +/- 311 mosmol/kg. To study the regulation of AQP-2, immature and adult rats were kept on ad libitum intake or were water-deprived. Under normal conditions, AQP-2 levels in the immature rat were significantly lower (52.3 +/- 5.8%, P < 0.001) than in the adult. However, after dehydration the expression increased to adult levels. Interestingly, the increase in AQP-2 observed in the immature kidney was not accompanied by a proportional increase in urine osmolality. To rule out a potential alteration in AQP-2 trafficking, the transport of this water channel was investigated in a group of rats subjected to dehydration, treated with desmopressin acetate (dDAVP), or water loaded. Dehydration and dDAVP stimulated translocation of AQP-2 from intracellular vesicles to the plasma membrane, whereas water loading caused a shift of AQP-2 channels back to intracellular vesicles in both adult and immature animals. In summary, AQP-2 expression and trafficking in the immature kidney is appropriately stimulated by water deprivation and dDAVP. However, urine osmolality remained significantly decreased. From this study, it is concluded that although AQP-2 expression may play a role in the development of urine concentrating abilities, there still is a significant defect, yet to be defined, distal to AQP-2.

Animals↗
PubMed1997

[Investigation on matrix degrading enzymes of lumbar intervertebral discs].

Changes in the macromolecular matrix of the intervertebral disc may predispose to biomechanical failure of the disc. Such changes would involve extracellular enzymes capable of altering the collagen and proteoglycan of the disc matrix. In this study, tritium-labeled type I collagen was used as a substrate to estimate the activity of collagenase in the discs of 41 cases of lumbar disc protrusion (LDP) patients by surgical intervention. The annulus fibrous (AF) and nucleus pulposus (NP) were measured separately. 34 normal discs harvested by autopsy acted as controls. For estimation of relative neutral proteinase content of 6 normal and 16 degenerated lumbar discs, polyacrylamide gelelectrophoresis (PAGE), heat-denatured collagen as a substrate, and photo-density scanning with peak area autocalculating system were adopted. The results presented that both AF and NP of the normal discs had a similar lower collagenolytic activity and a very limited activity of neutral proteinase, while the degenerated discs showed a higher activity, especially in the degenerated NP. The extruded type of LDP got a higher collagenolytic activity in NP than that of the prolapsed LDP. The fact showed that the matrix degrading enzymes play a very important role in the process of lumbar disc degeneration. The difference of disc degeneration is the biochemical basis of different clinical types of LDP. Matrix degrading enzyme system is a very complexed multienzymatic system. Other neutral proteinases may join this system besides the collagenase.

Adolescent↗
PubMed1997

[Effect of perilymphatic fistula on distortion product otoacoustic emissions in guinea pigs].

Perilymphatic fistula was induced in 11 healthy guinea pigs to study its effects on distortion product otoacoustic emissions (DPOAEs). DPOAE amplitudes decreased significantly right after formation of the fistula (P < 0.01), and recurred to near pretreatment level in animals whose fistula healed. The amplitude remained below pretreatment level 18 days after fistulization in those animals whose fistula failed to heal. Under light microscope, the organ of Corti was seen normal. The authors feel that DPOAEs may be helpful in detecting perilymphatic fistula.

Acoustic Stimulation↗
PubMed1997

[Outward character and inner quality of Bombyx Batryticatus, Carapax Trionycis, Squama Manitis and endothelium corneum Gigeriae Galli after frying].

According to the requirement for outward character in processing traditional Chinese medicines, Bombyx Batryticatus, Carapax Trionycis, Squama Manitis and Endothelium Corneum Gigeriae Galli, which are four kinds of often used traditional Chinese animal medicines, were fried, the contents of amino acids in each kind were determined, and investigate the inner quality of each kind of the processed product was investigated with reference to other standards.

Amino Acids↗
PubMed1997

[Identification of G6PD gene mutations in several nationalities from Yunnan province].

OBJECTIVE: To analyze the G6PD gene mutations in several nationalities from Yunnan province. METHODS: G6PD gene mutation of 29 samples from G6PD deficient patients were analyzed by using common and mis-matched primering PCR followed by restriction enzyme digestion. The samples were collected from Yunnan province among several nationalities. RESULTS: In these 29 cases, 20 were of two known mutations, including 19 of 1388 (G-->A) and 1 of 1376 (G-->T) mutation. The 7 cases of national minorities, including 3 of Yi ([symbol: see text]), 2 of Bai ([symbol: see text]), 1 of Dai ([symbol: see text]), and 1 of Naxi ([symbol: see text]), were all 1388 mutations. No report of the G6PD gene 1388 mutation in these ethnic groups was published excepting for Dai. CONCLUSION: The mutation probably had been prevalent before the emergence of these national minorities. The approximate rate of G6PD gene mutations provided in Yunnan province may, in some respects, help to interpret the molecular evolution.

Asian People↗
PubMed1997

[Determination of Keganmin tablet with multi-wavelength K-factor spectrophotometry].

The contents of phenacetin, aminopyrine and caffeine in Keganmin tablet were determined simultaneonsly with multiwavelength K -factor spectrophotometry. The result is accurate and the method is rapid. The average recoveries and relative standard deviations of the analysis for phenacetin, aminopyrine and caffeine were 99.91%, 0.41%; 100.1%, 0.29%; 100.1%, 0.56%, respectively.

Aminopyrine↗
PubMed1997

Comparative study of effects of three kinds of herbal mixture decoctions on improving immune senescence and free radical metabolism.

OBJECTIVE: To verify from the aspects of immune senescence and free radical metabolism that "removing blood stasis as well as tonifying kidney is an ideal way to delay aging" and further investigate the anti-aging mechanism of this therapy. METHODS: In the first period, the old mice were separately fed with the herbal decoction of the recipe of tonifying kidney, or of removing blood stasis, or of tonifying kidney and removing blood stasis for four weeks, and then IL-2 production of splenic lymphocytes, IL-1 production of peritoneal macrophages, SOD, CAT and GSH-Px activity in erythrocytes, and LPO contents in liver and brain were compared between the young control group and the old control group, or the old control group and each of the old medication groups. In the second period, the adult mice inhaled ozone or the splenic lymphocytes from adult mice were cultured in the medium containing peroxide hydrogen. The effects of free radicals on immune system and the reversion of the herbal decoction of the recipe of removing blood stasis as well as tonifying kidney were observed. RESULTS: The activities of IL-1, IL-2, SOD, CAT and GSH-PX in old mice were significantly lower than those in young mice, and LPO contents were higher. The three herbal decoctions all have reversing effects on each of these parameters except that the decoction of removing blood stasis has inhibitory effects on IL-1 and IL-2 production. The effect of the decoction of removing blood stasis as well as tonifying kidney was the best among the three decoctions, and it can also reverse the impaired production of IL-2 by ozone in vivo and peroxide hydrogen in vitro. CONCLUSIONS: The therapeutic method of removing blood stasis as well as tonifying kidney is an ideal way to delay aging, and its effects to improve immune senescence is correlated with the decrease of free radical damages.

Aging↗
PubMed1997

[Distortion product otoacoustic emissions on neonates].

Distortion product otoacoustic emissions (DPOAE) is evoked by two pure-tones (f1, f2). It is a kind of reflex of cochlea. In order to know the effect of different elements on DPOAE of neonates, we used GSI 60 DPOAE to detect the DPOAE of 40 ears of 20 neonates. The results showed that when f1 was below 1,000 Hz, the incidence of DPOAE was very low. When the f1 was between 1,400 and 4,000 Hz, the incidence of detectability was more than 90%. The amplitude of DPOAE was low within lower frequency area, while f1 was between 1,000 and 4,000 Hz, the amplitude was higher. We consider that the DPOAE of neonates were easily affected by noise, stimulus intensity, the function of middle ear, etc. We must pay attention to these elements when we use DPOAE to test hearing function of neonates.

Female↗
PubMed1997

Dihydropyrimidine dehydrogenase activity in hepatocellular carcinoma: implication in 5-fluorouracil-based chemotherapy.

Dihydropyrimidine dehydrogenase (DPD) is the initial, rate-limiting enzyme in the catabolism of 5-fluorouracil, one of the most widely used cancer chemotherapeutic agents. Previous studies have demonstrated the clinical importance of determination of DPD in cancer patients, suggesting that the efficacy and toxicity of 5-fluorouracil may directly relate to the DPD activity in both tumor and host tissues. In the present study, DPD activity was determined in 50 pairs of tumor and uninvolved liver specimens in Chinese cancer patients with hepatocellular carcinoma. Mean enzyme activity in uninvolved liver tissues (0.45 +/- 0.02 nmol/min/mg protein) was significantly higher than that in tumor specimens (0.34 +/- 0.03 nmol/min/mg protein). Statistical analysis revealed no significant differences in DPD activity of tumor and uninvolved liver specimens among different age and gender groups. Compared to previously reported tumor studies, hepatomas were found to have relatively high DPD activity. Since high levels of DPD would be expected to metabolize 5-fluorouracil, these findings may provide an explanation for the relative 5-fluorouracil resistance of hepatoma and may have implications for designing a new therapeutic strategy such as modulation of 5-fluorouracil chemotherapy by DPD inhibitors.

Adult↗
PubMed1996

Cardiac spectral power reflects parasympathetic but not sympathetic nervous system activity in a clinical population.

The purpose of this short communication is to report our clinical findings regarding the use of the low frequency (LF, 0.02-0.15 Hz) and high frequency (HF, > 0.15 Hz) components of the spectral decomposition of heart-rate as indices of sympathetic (SNS) and parasympathetic nervous system (PNS) activity, respectively. Thirty-two females with histologically confirmed ovarian cancer, ranging in age from 46-72 years, participated in an autonomic assessment protocol consisting of a resting heart rate recording and several ANS function tests. The LF, HF and total power measures from the spectral decomposition were highly correlated with one another. In addition, the spectral components were most highly correlated with measures of PNS activity, i.e. standard deviation of heart rate at rest and the ratio of the six longest to the six shortest R-R intervals during deep breathing (E:I ratio). It is concluded, as other researchers have stated, that the use of the HF component of the HR spectrum as a measure of PNS activity is warranted, but caution must be used when interpreting the LF component.

Aged↗
PubMed1996

Protein interaction with immobilized metal ion affinity ligands under high ionic strength conditions.

An investigation into the adsorption behavior under batch equilibrium binding conditions of hen egg white lysozyme (HEWL) with the immobilized metal ion affinity chromatographic adsorbent, Cu(2+)-IDA Sepharose CL-4B, in the presence of high concentrations of NaCl or KCl has been undertaken. When the concentration of NaCl or KCl in the adsorption buffer was < or = 0.2 M, the adsorption data correlated with predictions based on the Langmuir model. However, when the salt concentration was > or = 0.5 M, the adsorption data appeared to follow the Freundlich-Langmuir model under these higher ionic strength conditions. Under elevated ionic strength conditions, the protein-ligand interactions were shown to involve positive cooperativity by Scatchard plot analysis of the experimental data. The number, n, of interacting protein molecules increased with the salt concentration, while the apparent dissociation constant Kd under these high ionic strength conditions was less dependent on the type of salt present in the adsorption buffer. These studies reveal that the binding of Cu(2+)-IDA Sepharose CL-4B to HEWL acceptor molecules under conditions of high ionic strength is characteristic of general heterogeneous interactions, whereby the immobilized metal ion affinity chromatography (IMAC) ligands bind to a protein acceptor undergoing isodesmic indefinite self-association and multisite attachment. As a consequence, these results on the adsorption behavior of HEWL have important general implications for the preparative use of immobilized metal ion affinity adsorbents in packed and expanded bed systems, particularly with regard to the resolution and productivity of the separation for the target protein. In addition, the results from these studies are relevant to investigations involving analytical affinity chromatographic or biosensor assessment of the interaction of proteins with immobilized IMAC ligands when high ionic strength equilibration feedstocks or conditions are employed.

Adsorption↗
PubMed1996

Activation of protein kinase C in human uterine smooth muscle induces connexin-43 gene transcription through an AP-1 site in the promoter sequence.

Myometrial connexin-43 gap junctions are scarce throughout gestation but appear in large numbers at term to facilitate contractions during labor. The mechanisms that regulate this process are incompletely characterized. This report investigates the effects of protein kinase C activation on the regulation of connexin-43 gene transcription in human uterine smooth muscle cells. In primary myometrial cells treated with phorbol ester, transient increases in c-Fos and c-Jun protein levels were observed at 2-4 h, followed by significant increases in connexin-43 protein levels at 6-8 h. Nuclear run-on transcription analysis showed an increase in connexin-43 transcription 3 h after phorbol ester treatment. AP-1 sites were identified in the sequence of the 5'-flanking promoter region of the human connexin-43 gene at 44 and 1000 base pairs upstream of transcription start. Transcription from a reporter plasmid containing the proximal human connexin-43 promoter was increased in transfected primary cultures treated with phorbol ester. Mutation of the proximal AP-1 site in the promoter abolished the phorbol ester-dependent transactivation. This work provides evidence that transcription of the human connexin-43 gene is induced through protein kinase C activation in uterine smooth muscle cells, and that the induction involves up-regulation and activation of c-Jun and c-Fos.

Animals↗
PubMed1996

Sequence of bovine carbonic anhydrase VI: potential recognition sites for N-acetylgalactosaminyltransferase.

Carbonic anhydrases (CAs I-VII) are products of a gene family that encodes seven isoenzymes and several CA-related proteins. We report the cloning and sequencing of the cDNA clones encoding one of these isoenzymes, CA VI, from bovine submaxillary gland. The translated polypeptide consists of 319 amino acids, including a signal peptide (14 amino acids) typical of secreted proteins. The predicted mature protein contains 305 amino acids including a 13-amino-acid C-terminal sequence that is also present in the sheep but absent in human CA VI. The deduced mature bovine protein is 87% and 68% identical to that of sheep and human CA VI, respectively. Active-site residues of the enzyme, as well as the three zinc-binding histidines and the two cysteines involved in an intra-chain disulphide bond, are all conserved in the three species. Two potential Asn-glycosylation sites are also conserved, both of which appear to be glycosylated in sheep and bovine CA VI. Two potential peptide recognition sequences are present in bovine CA VI for the glycoprotein hormone: N-acetylgalactosaminyltransferase (GalNAc-transferase), which is one of the two transferases required to form GalNAc-4-SO4 in bovine CA VI-linked oligosaccharides. Specifically, these two sequences are Asp-Leu-Lys-Met-Lys-Lys and Ile-Thr-Lys-Arg-Lys-Lys. Comparison of these sequences with sheep and human CA VI sequences indicates that distinct glycoforms of CA VI could exist in submaxillary gland from different species.

Amino Acid Sequence↗
PubMed1996

Mental stress--induced myocardial ischemia and cardiac events.

OBJECTIVE: To assess the clinical significance of mental stress-induced myocardial ischemia in patients with coronary artery disease (CAD). DESIGN AND SETTING: Cohort study in outpatients in a tertiary care teaching hospital assessed at baseline and followed up for up to 5 years. SUBJECTS: A total of 126 volunteer patients (112 men, 14 women; mean age, 59 years) with documented CAD and exercise-induced myocardial ischemia. OUTCOME MEASURES: Patients underwent baseline mental stress and exercise testing using radionuclide ventriculography and 48-hour Holter monitoring. Patients were subsequently contacted by mailed questionnaires or telephone to document cardiac events, including death, nonfatal myocardial infarction, and cardiac revascularization procedures. Logistic regression and Cox proportional hazards models were used to examine the prognostic value of the ischemic measures after adjusting for such potential confounding factors as age, baseline left ventricular ejection fraction (LVEF), and history of myocardial infarction. RESULTS: Twenty-eight patients (22%) experienced at least 1 cardiac event. Baseline mental stress-induced ischemia was associated with significantly higher rates of subsequent cardiac events (odds ratio, 2.8; 95% confidence interval [CI], 1.0-7.7; P < .05). The LVEF change during mental stress was significantly related to event-free survival (risk ratio [RR], 2.4; 95% CI, 1.12-5.14; P = .02), controlling for age, history of prior myocardial infarction, and baseline LVEF. This relationship remained significant after controlling for electrocardiogram (ECG)-defined ischemia during exercise (RR, 2.2; 95% CI, 1.01-4.81; P < .05). The RR for ECG-defined ischemia during exercise testing was 1.9 (95% CI, 0.95-3.96; P = .07) and the RR for ambulatory ECG ischemia was 0.75 (95% CI, 0.35-1.64; P = .47). CONCLUSIONS: The presence of mental stress-induced ischemia is associated with significantly higher rates of subsequent fatal and nonfatal cardiac events, independent of age, baseline LVEF, and previous myocardial infarction, and predicted events over and above exercise-induced ischemia. These data suggest that the relationship between psychological stress and adverse cardiac events may be mediated by the occurrence of myocardial ischemia.

Aged↗
PubMed1996

Cyclin-dependent kinases are inactivated by a combination of p21 and Thr-14/Tyr-15 phosphorylation after UV-induced DNA damage.

The cyclin-dependent kinase (CDK) inhibitor p21 is induced by the tumor suppressor gene product p53 and is thought to be important for the arrest of the cell cycle following DNA damage. Here we have investigated the contribution of p21 in inhibiting different cyclin-CDK complexes that drive different cell cycle transitions following UV irradiation-induced DNA damage in normal human fibroblasts and immortalized rodent fibroblasts. When cells were exposed to a low dose of UV irradiation, both p53 and p21 were induced; the protein kinase activities associated with Cdc2, Cdk2, and Cdk4 were inhibited; and there was a good correlation between their inhibition and binding to p21. p21 alone is likely to be sufficient for the inhibition of Cdk2 because all the cyclin-complexed forms of Cdk2 were associated with p21 after irradiation. In contrast, only a small proportion of Cdk4 and Cdc2 was complexed with p21, although the level of Cdk4 associated with either p21 or p27 was increased after irradiation. Furthermore, recombinant p21 added to an unirradiated cell lysate at the same level as that induced by irradiation damage inhibited only the kinase activity associated with Cdk2. Cdc2 is likely to be inhibited by Thr-14/Tyr-15 phosphorylation after irradiation because Cdc2 was tyrosine-phosphorylated, and recombinant Cdc25 was able to increase its kinase activity significantly. Taken together, these results suggest that different CDKs are inhibited by different mechanisms following UV-induced DNA damage: Cdk2 is inhibited by the elevated level of p21; Cdk4 is inhibited by cooperation of p21 with other CDK inhibitors, like p27, and possibly by phosphorylation; and Cdc2 is inhibited by Thr-14/Tyr-15 phosphorylation. It is likely that these underlying mechanisms that inactivate CDKs are similar for other kinds of DNA damage.

Amino Acid Sequence↗