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Biomedical subjects

J Qiu

Publications and source records attributed to J Qiu.

At least 109 records · Page 6Linked to original sources
PubMed1999

[Clinic and immunophenotypic studies on midline malignant histiocytosis].

OBJECTIVE: To understand the clinic opatholgic changes of midline malignant histiocytosis (MMH), and to explain the source of atypical lymphoid cells (ALC) of MMH, so as to search after the relation between MMH and malignant lymphoma. METHOD: Histopathologic section of 39 cases of MMH were taken HE staining and the histopathologic changes were obsered under microscope. The immunohistochemical staining was also used to examine the immunophenotype of ALC. RESULT: 1. Pathologic changes of MMH: coaglation necrosis and mixed inflammatory cells infiltration, with epithelial infiltration which distributed around the center of blood vessel were their characteristics. 2. Immunohistochemical staining result: 28 in 39 cases of MMH (71.8%) expressed the immunophenvtype of T-cell; among them 13 (33.3%) were finded both positive reaction to CD3 and CD57 antigens with ALCs at the same time. CONCLUSION: According to immunophenotypic studies, most ALCs came from proliferation and infiltration of atypical T cell. ALCs of MMH expressed not only T-cell markers (CD3), but also NK-associated antigen (CD57). MMH was a mucosa related peripheral T/NK cell lymphoma originally.

Adult↗
PubMed1999

[Investigation of the reaction of iso-propylamine on propylene oxide by Fourier transform infrared spectroscopy].

Fourier transform infrared spectroscopy method has been developed for in-situ monitoring the reaction of iso-propylamine on propylene oxide without the need to sample the reaction medium. The profile of the reaction and the influences of conditions can be directly reflected in the feature absorbance changes of the reactant and product at 826 cm(-1) and 1069 cm(-1), respectively. It is shown that the in situ infrared spectroscopy is a powerful technique to investigate the mechanism and kinetics of the reaction and to optimize the control conditions.

English Abstract↗
PubMed1999

[Monitoring glucoamylase fermentation with infrared spectroscopy].

The glucoamylase fermentation was investigated with Fourier transform infrared spectroscopy. During the cultivation, the variation of carbon and nitrogen source can be reflected from the infrared spectra. In most cases, the complex media are used to cultivate cells or bacteria. It is difficult to construct calibration samples with synthetic mixtures which can represent the composition of real broth. The infrared spectral data of the real broth and off-line chemical analysis results were used to establish the calibration model. The model is successfully used to predict the concentrations of total sugar, reduced sugar, and nitrogen in real broth. The correlation coefficients between the infrared analysis results and chemical analysis are 0.999, 0.990 and 0.974 for total sugar, reduced sugar and nitrogen, respectively. The bacteria, culture and operating condition are relatively stable during the practical productive processes. The method can be used to monitor the industrial processes.

Aspergillus niger↗
PubMed1998

Partial functional deficiency of E160D flap endonuclease-1 mutant in vitro and in vivo is due to defective cleavage of DNA substrates.

To assess the roles of the active site residues Glu160 and Asp181 of human FEN-1 nuclease in binding and catalysis of the flap DNA substrate and in vivo biological processes of DNA damage and repair, five different amino acids were replaced at each site through site-directed mutagenesis of the FEN-1 gene. The mutants were then expressed in Escherichia coli and purified using a His-tag. Even though the mutants bind to the flap DNA to different degrees, most of the mutants lost flap nuclease activity with the exception of an E160D mutant. This mutant retained wild type-like binding ability, specificity, and partial catalytic activity. Detailed steady state and pre-steady state kinetic analysis revealed that the functional deficiency of this mutant was due to retardation of the endonucleolytic cleavage. When the mutant enzyme E160D was expressed in yeast, it partially complements the biological functions of the homologous yeast gene, RAD27, and reverses the hyper-temperature lethality and hypersensitivity to methyl methanesulfonate, in a manner corresponding to the in vitro activity.

Base Sequence↗
PubMed1998

Human milk lactoferrin inactivates two putative colonization factors expressed by Haemophilus influenzae.

Haemophilus influenzae is a major cause of otitis media and other respiratory tract disease in children. The pathogenesis of disease begins with colonization of the upper respiratory mucosa, a process that involves evasion of local immune mechanisms and adherence to epithelial cells. Several studies have demonstrated that human milk is protective against H. influenzae colonization and disease. In the present study, we examined the effect of human milk on the H. influenzae IgA1 protease and Hap adhesin, two autotransported proteins that are presumed to facilitate colonization. Our results demonstrated that human milk lactoferrin efficiently extracted the IgA1 protease preprotein from the bacterial outer membrane. In addition, lactoferrin specifically degraded the Hap adhesin and abolished Hap-mediated adherence. Extraction of IgA1 protease and degradation of Hap were localized to the N-lobe of the bilobed lactoferrin molecule and were inhibited by serine protease inhibitors, suggesting that the lactoferrin N-lobe may contain serine protease activity. Additional experiments revealed no effect of lactoferrin on the H. influenzae P2, P5, and P6 outer-membrane proteins, which are distinguished from IgA1 protease and Hap by the lack of an N-terminal passenger domain or an extracellular linker region. These results suggest that human milk lactoferrin may attenuate the pathogenic potential of H. influenzae by selectively inactivating IgA1 protease and Hap, thereby interfering with colonization. Future studies should examine the therapeutic potential of lactoferrin, perhaps as a supplement in infant formulas.

Adhesins, Bacterial↗
PubMed1998

Saccharomyces cerevisiae exonuclease-1 plays a role in UV resistance that is distinct from nucleotide excision repair.

Two closely related genes, EXO1 and DIN 7, in the budding yeast Saccharomyces cerevisiae have been found to be sequence homologs of the exo1 gene from the fission yeast Schizosaccharomyces pombe . The proteins encoded by these genes belong to the Rad2/XPG and Rad27/FEN-1 families, which are structure-specific nucleases functioning in DNA repair. An XPG nuclease deficiency in humans is one cause of xeroderma pigmentosum and those afflicted display a hypersensitivity to UV light. Deletion of the RAD2 gene in S. cerevisiae also causes UV hypersensitivity, due to a defect in nucleotide excision repair (NER), but residual UV resistance remains. In this report, we describe evidence for the residual repair of UV damage to DNA that is dependent upon Exo1 nuclease. Expression of the EXO1 gene is UV inducible. Genetic analysis indicates that the EXO1 gene is involved in a NER-independent pathway for UV repair, as exo1 rad2 double mutants are more sensitive to UV than either the rad2 or exo1 single mutants. Since the roles of EXO1 in mismatch repair and recombination have been established, double mutants were constructed to examine the possible relationship between the role of EXO1 in UV resistance and its roles in other pathways for repair of UV damaged DNA. The exo1 msh2 , exo1 rad51 , rad2 rad51 and rad2 msh2 double mutants were all more sensitive to UV than their respective pairs of single mutants. This suggests that the observed UV sensitivity of the exo1 deletion mutant is unlikely to be due to its functional deficiencies in MMR, recombination or NER. Further, it suggests that the EXO1 , RAD51 and MSH2 genes control independent mechanisms for the maintenance of UV resistance.

Amino Acid Sequence↗
PubMed1998

Use of in vitro systems to study male germ cell development in neonatal rats.

The aim of this review is to summarize ways in which in vitro approaches have allowed us to investigate several aspects of gametogenesis in the male. In our laboratory, we have established both organ culture and cell co-culture methodologies and applied them to questions focused on cellular and molecular events important for development of primitive spermatogonia, or gonocytes, in testes of neonatal rats. We have described their postnatal reinitiation of mitosis and their migration to the basal lamina in anticipation of basal compartment formation and, through use of these in vitro systems, we have identified several mechanisms regulating these processes. These include matrix influence on mitosis and migration, adhesive mechanisms active between gonocytes and Sertoli cells, and involvement of the Kit receptor on germ cells and its ligand from Sertoli cells in supporting gonocyte migration, as described below.

Animals↗
PubMed1998

Antigenic and immunological mimicry of peptide mimotopes of Lewis carbohydrate antigens.

Peptides may substitute for carbohydrates in reactions with carbohydrate-specific molecules. Recently, we found that peptides containing aromatic residues mimic mucin and histo-blood group related carbohydrate epitopes, eliciting polyclonal responses cross-reactive with bacterial and viral antigens that express these carbohydrate forms. These results demonstrate that peptides can function in in vivo and in vitro models as carbohydrate surrogate antigens. To further explore the nature of the antigenic and immunogenic properties of such mimotopes, synthetic peptides with aromatic amino acids were tested to delineate reactivity patterns with several anti-neolactoseries monoclonal antibodies (MAbs). These MAbs recognize biologically important conformations of the histo-blood group related Lewis antigens expressed on the surface of a variety of human cancers. Results by ELISA demonstrate that the MAbs can distinguish particular peptide motifs that include the sequences GGIYYPYDIYYPYDIYYPYD, GGIYWRYDIYWRYDIYWRYD and GGIYYRYDIYYRYDIYYRYD. Substitution of Arg by Pro diminished the reactivity of the anti-Lewis Y (LeY) MAb BR55-2. Binding of LeY to BR55-2 was inhibitable by the Arg containing peptides. Serum against all three peptides displayed reactivity with synthetic histo-blood group related antigen probes. Immunologic presentation of the peptides as multiple antigen peptides (MAPs) improved peptide ability to induce LeY specific immune responses. Serum bound to human tumor cells that preferentially expressed neolactoseries antigens, but not to normal tissues. Immunoprecipitation of human breast tumor cell lysates before and after treatment with tunicamycin confirmed serum carbohydrate binding. The anti-peptide sera mediated tumor cell killing by complement mediated cytotoxicity. These results indicate that mapping peptide epitopes with anti-carbohydrate antibodies can lend to defining antibody fine specificities that can go undetected by screening of carbohydrate antigens alone. In addition, these results confirm that peptides and carbohydrates can bind to the same antibody binding site and that peptides can structurally mimic salient features of carbohydrate epitopes.

Amino Acid Sequence↗
PubMed1998

Stereoselective steady state disposition and action of propafenone in Chinese subjects.

AIMS: To investigate the steady state disposition and action of racemic propafenone and its enantiomers and the potential for an enantiomer-enantiomer interaction in Chinese subjects. METHODS: Eight healthy male Chinese individuals received in a double-blind, randomized, cross-over study racemic propafenone (150 mg every 6 h), (S)-, and (R)-propafenone (150 mg each every 6 h) and placebo orally for 4 days. During the last dosing interval the plasma concentrations of both enantiomers of propafenone were measured and ECG, blood pressure (MAP) and heart rate were monitored. RESULTS: Whereas the apparent elimination half-life (t1/2,z), mean residence time (MRT) and time to reach peak concentrations (tmax) of (S)- and (R)-propafenone were similar and independent of the administered agent, significant differences were observed in the apparent oral clearance (CLO) of the enantiomers. During dosing with racemic propafenone CLO of (S)- and (R)-propafenone averaged (+/-s.d.) 1226+751 and 1678+625 ml min(-1), respectively (P=0.024). Following the administration of the pure enantiomers CLO of (S)-propafenone increased (P= 0.007) to 2028+/-959 ml min(-1) and that of (R)-propafenone was reduced (P= 0.042) to 1318+/-867 ml min(-1). Both enantiomers and the racemate caused about a 10% increase in the QRS duration (P<0.05) and PR-interval (P<0.01) when compared with placebo. The increase in maximum exercise heart rate was significantly (P<0.05) attenuated only at 3 h following the administration of the racemate and the S-enantiomer. MAP and QTC were not affected significantly. CONCLUSIONS: These data indicate that the stereoselective disposition of propafenone is similar in Chinese and Caucasian subjects (previously published findings), the (R)-enantiomer being cleared more rapidly. A similar enantiomer-enantiomer interaction also occurred. Thus, when the racemate was given, the elimination of (S)-propafenone was impaired and that of the (R)-form accelerated compared with single enantiomer administration. The results indicate that dosage adjustments are probably not required in Chinese patients receiving propafenone.

Adult↗
PubMed1998

Expression of active human tissue-type plasminogen activator in Escherichia coli.

The formation of native disulfide bonds in complex eukaryotic proteins expressed in Escherichia coli is extremely inefficient. Tissue plasminogen activator (tPA) is a very important thrombolytic agent with 17 disulfides, and despite numerous attempts, its expression in an active form in bacteria has not been reported. To achieve the production of active tPA in E. coli, we have investigated the effect of cooverexpressing native (DsbA and DsbC) or heterologous (rat and yeast protein disulfide isomerases) cysteine oxidoreductases in the bacterial periplasm. Coexpression of DsbC, an enzyme which catalyzes disulfide bond isomerization in the periplasm, was found to dramatically increase the formation of active tPA both in shake flasks and in fermentors. The active protein was purified with an overall yield of 25% by using three affinity steps with, in sequence, lysine-Sepharose, immobilized Erythrina caffra inhibitor, and Zn-Sepharose resins. After purification, approximately 180 microgram of tPA with a specific activity nearly identical to that of the authentic protein can be obtained per liter of culture in a high-cell-density fermentation. Thus, heterologous proteins as complex as tPA may be produced in an active form in bacteria in amounts suitable for structure-function studies. In addition, these results suggest the feasibility of commercial production of extremely complex proteins in E. coli without the need for in vitro refolding.

Cloning, Molecular↗
PubMed1998

Differential regulation of angiotensin II receptor subtypes in the adrenal gland: role of aldosterone.

It has been shown that aldosterone potentiates the action of angiotensin II (Ang II) in cultured rat vascular smooth muscle cells solely by increasing the number of Ang II receptors. The mechanisms responsible for aldosterone-Ang II interactions in the adrenal gland are unknown. The present study was designed to investigate the effect of aldosterone on expression of Ang II receptor subtypes (AT1 and AT2) in the adrenal gland. Seven-week-old male Wistar rats were treated for 2 weeks with either aldosterone (0.05 microg/h, n=14) or vehicle (n=14) by use of implanted osmotic minipumps. Systolic blood pressure was not altered by aldosterone treatment. Plasma aldosterone levels were higher in aldosterone-treated rats (181+/-53 pg/mL) compared with vehicle-treated rats (33+/-21 pg/mL, P<0.05). Northern blot analysis and radioligand binding assay showed that adrenal AT1 mRNA levels and AT1 receptor density in aldosterone-treated rats were not statistically different from those of vehicle-treated rats. However, immunohistochemical studies showed that the highest adrenal AT1 receptor expression was shifted from the zona glomerulosa to the zona fasciculata after aldosterone treatment. In contrast, adrenal AT2 mRNA and AT2 receptor density in aldosterone-treated rats were decreased by approximately 50% and 40%, respectively, compared with vehicle-treated rats (P<0.05). Aldosterone-induced decrease in adrenal AT2 receptor expression occurred mainly in the medulla. Thus, aldosterone differentially modulates the expression of AT1 and AT2 receptors in the adrenal gland. Although the function of the AT2 receptor in the adrenal gland is largely unknown, our data indicate that aldosterone may modulate the effect of Ang II by altering the location of AT1 receptors and by reducing the number of AT2 receptors in the adrenal gland.

Adrenal Glands↗
PubMed1998

Salt-sensitive hypertension induced by sensory denervation: introduction of a new model.

To test the novel hypothesis that neonatal degeneration of capsaicin-sensitive sensory nerves causes the rat to respond to a salt load with a significant and sustained rise in blood pressure, newborn Wistar rats were given 50 mg/kg capsaicin subcutaneously on the 1st and 2nd day of life. Control rats were treated with vehicle. Immediately after the weanling period, male rats were divided into 4 groups and fed different sodium diets for 2 weeks: capsaicin pretreatment plus high sodium diet (4%, CAP-HS), capsaicin plus normal sodium diet (0.5%, CAP-NS), control plus high sodium diet (CON-HS), and control plus normal sodium diet (CON-NS). Both tail-cuff systolic blood pressure and mean arterial pressure with anesthesia were significantly higher in CAP-HS than in CAP-NS, CON-HS, and CON-NS (P<0.05), but they were not different among the latter 3 groups. Radioimmunoassay revealed that levels of calcitonin gene related peptide in dorsal root ganglia were markedly decreased by capsaicin treatment (P<0.05). Twenty-four-hour urine volume and urine sodium excretion were significantly lower in CAP-HS than in CON-HS but were higher in CAP-HS and CON-HS compared with CAP-NS and CON-NS (P<0.05). Urine potassium excretion was not different among the 4 groups. Thus, this study provides the first evidence that neonatal degeneration of capsaicin-sensitive sensory nerves renders the rat salt-sensitive in terms of blood pressure regulation. Furthermore, our data suggest that neonatal capsaicin treatment may impair renal sodium and water excretion responses to high sodium intake. This model will provide a novel experimental paradigm for exploring underlying molecular mechanisms linked with salt-sensitive hypertension and sensory nerve function.

Animals↗
PubMed1998

Nongenomic mechanisms of glucocorticoid inhibition of nicotine-induced calcium influx in PC12 cells: involvement of protein kinase C.

Nongenomic mechanisms of corticosterone (B) inhibition of nicotine (Nic)-induced calcium influx were investigated in PC12 cells. Corticosterone could rapidly inhibit the Ca2+ influx induced by Nic, and BSA-conjugated B had a similar inhibitory effect. The inhibition of Nic-induced Ca2+ influx by B could be mimicked by protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate) and reversed by PKC inhibitors, chelerythrine chloride and Gö6976. When PC12 cells were pretreated with pertussis toxin, the inhibitory effect of B on Nic-induced Ca2+ influx was blocked. Both B and BSA-conjugated B could activate PKC activity, with the maximal responses at 10(-9) and 10(-7) M at 37 C, respectively. The dose-response curve was bell shaped. At 25 C, however, the dose-response curve considerably shifted to the right, and B was most potent at 10(-5) M. The time course showed that PKC activity was highest at 5 min of B's action. The results suggest that B might act via putative membrane receptors and inhibit the Ca2+ influx induced by Nic through the pertussis toxin-sensitive G protein-PKC pathway and that PKC plays an important role in the mechanisms of glucocorticoid nongenomic action.

Animals↗
PubMed1998

Leptin is not necessary for gestation and parturition but regulates maternal nutrition via a leptin resistance state.

Leptin levels are significantly elevated in pregnant mice, rats and humans suggesting a critical role for leptin during gestation. To address whether leptin plays a putative role in the physiology of pregnancy, we asked whether a mouse pregnancy would be affected by the complete absence of leptin from both the mother and fetuses. Thus, leptin-deficient ob/ob females were first treated with exogenous leptin and then mated to similarly treated ob/ob males. All resulting fetuses have an ob/ob genotype and lack like their mothers any endogenous leptin production. Withdrawal of leptin treatment at 0.5, 6.5, 10.5 and 19.5 days p.c. did not affect any stage of the pregnancy despite a gradual return of the mothers to an obese state. However, some mice had delayed gestation periods of 21-23 days which were associated with prolonged parturition. The pups were normally delivered with no obvious signs of deformities although none survived beyond a day after delivery due to failure of lactation. Monitoring daily food intake of pregnant ob/ob females treated throughout gestation with leptin revealed significantly elevated levels of food intake from day 10 p.c. and onward demonstrating an attenuation of a leptin response during pregnancy and a leptin resistance effect. These studies demonstrate that in the mouse, leptin is not a critical molecule for implantation, gestation, fetal growth and parturition but that the leptin resistance effect at mid-gestation aims to stimulate food intake thus providing sustained energy resources for pregnancy.

Animal Nutritional Physiological Phenomena↗
PubMed1998

Preliminary observation on the correlation between nm23 expression and Ki-67 antigen with early metastasis of human osteosarcoma.

OBJECTIVES: To detect the nm23 expression in osteosarcoma, analyze the correlation between nm23 expression and early metastasis and to study the relation between nm23 expression with tumor differentiation and cell proliferation, as defined by Ki-67 labeling. METHODS: nm23 oncoprotein expression was measured by immunohistochemical staining using formalin fixed, paraffin embedded sections of 39 surgically resected osteosarcomas and was compared with Ki-67 expression, histological findings and early metastasis. In each sample, the grading of immunoreactivity was recorded as 0, 1+, 2+ according to the percentage of nm23 and Ki-67 labeling cells respectively. RESULTS: The cases with more than 25% positive immunoreactivity of nm23 protein were detected in 48.7% of the total cases. There was no statistical difference between nm23 expression and early metastasis, but the cases with nm23 expression appeared to have a trend to get early metastasis. nm23 expression was significantly correlated with Ki-67 expression, which was associated with differentiation of the tumor cells. CONCLUSION: The role of nm23 as a tumor metastasis suppressor in osteosarcoma is less prominent. Both nm23 and Ki-67 may help predict the possibility of early metastasis in human osteosarcomas.

Adolescent↗
PubMed1998

Effect of epidermal growth factor and dexamethasone on explosive deafness.

OBJECTIVE: To study the expression of epidermal growth factor receptor (EGFR) on cochlear hair cells of normal and explosion-stricken guinea pigs and the effects of epidermal growth factor (EGF) and dexamethasone (DXM) treatment for blast hearing loss. METHODS: Immunohistochemical technique and auditory brainstem response (ABR) test were used. RESULTS: Scattered expression of EGFR was seen in inner hair cells (IHCs) and outer hair cells (OHCs) in normal guinea pigs. Segmentally distributing positive reaction was also located in stereocilia of hair cells. Distribution of EGFR reaction was seen in the cytoplasm of IHC 24 hours after exposure to blasts, and in the stereocilia 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 stereocilia also showed positive reaction. EGFR reaction reduced at two weeks, though positive reaction could still be found in the stereocilia of hair cells at one month. Combination of EGF and DXM administrations promoted hearing recovery significantly. CONCLUSIONS: The healing of injured hair cells may be related to EGF.

Animals↗