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Biomedical subjects

Y Ma

Publications and source records attributed to Y Ma.

At least 433 records · Page 24Linked to original sources
PubMed1996

[Anti-tumor activity and immune responses induced by human cancer-associated mucin core peptide].

Mucin molecules are displayed on most human cancer cell surface, and are different from that expressed on normal epithelial cells. The molecular structure of mucin core peptide (apomucin) was identified recently. However, the function of apomucin is only poorly understood. To further elucidate the role of apomucin in the modulation of cancers, this study was to investigate the immune responses induced by mucin core peptide in mice. The mucin core peptide was isolated from pancreatic cancer cell line SW1990. When mice immunized with this apomucin (10 micrograms/time x 6) plus DETOX, all mice developed delayed-type hypersensitivity (DTH) after challanged with apomucin or synthetic mucin core peptide MUC-2 or MUC-3, while the mice immunized with only apomucin did not develop DTH. No antibodies were detected by ELISA after immunization. When the splenic cells of vaccinated mice were cocultured with this apomucin (10-50 micrograms/ml) and rhIL-2 (50 U/ml) in vitro, the proliferated lymphocytes showed cytotoxicity against human cancer cells, including colon cancer, gastric cancer, pancreatic cancer and leukemia as measured by Cr-51 release assay. The cytotoxicity could be blocked by antibodies against MUC-2 and MUC-3. These results provide a rational basis for the use of apomucin as a vaccine to stimulate anti-tumor immunity.

Animals↗
PubMed1996

[RAAS changes due to dysfunction of pulmonary ventilation].

OBJECTIVE: RAAS was determined to investigate the relationship between their changes and the dysfunction of pulmonary ventilation for evaluating the pathogenesis of early pulmonary hypertension in chronic bronchitis with or without emphysema. METHODS: Angiotensin II (AT II), plasma renin activity (PRA) and aldosterone (Ald) were determined at 8:00 AM in sitting position for 30 minutes in 12 heathy nonsmokers, 50-60 years old, with normal functions of small airway, normal FEV1 and lung volumes, and in 23 patients with chronic bronchitis with or without emphysema. RESULTS: All patients with chronic bronchitis showed dysfunction of small airway with or without abnormalities of FEV1 and lung volumes. In healthy control group, the plasma PRA, AT II and Ald levels were 0.22 +/- 0.12 microgram.L-1.h-1 (x +/- sx), 52 +/- 7 ng/L and 315 +/- 26 pmol/L respectively comparing with those levels of 0.43 +/- 0.11 microgram.L-1.h-1, 197 +/- 32 ng/L and 388 +/- 59 pmol/L in aged patients with chronic bronchitis. It was found that dysfunction of small airway alone could cause remarkable elevation of PRA and AT II levels. In patients with mild pulmonary emphysema, the levels of PRA and AT II were significantly increased. The moderate pulmonary emphysema induced greatly increase of PRA, AT II and Ald levels. In patients with severe pulmonary emphysema, however, the plasma levels of PRA and AT II were significantly attenuated from the levels in moderate pulmonary emphysema while Ald level was still getting higher. There were no evidence to indicate the relationship between the changes of RAAS and hypoxemia. CONCLUSION: The elevation of AT II and PRA might partly be the pathogenesis of early pulmonary hypertension in COPD.

Aldosterone↗
PubMed1996

[A morphometric study on hippocampus of epileptic rats induced by coriaria lactone].

This experiment was carried out with these rats were injected with 3.8 microliters (19 micrograms) convulsive dosage of coriaria lactone (CL) in the left cerebral motor cortex of the forelimb to induce acute focal epilepsy, while the other 5 rats as controls (no seizure) received normal saline solution of the same volume and at the same location. The brains were taken after seizuring for 60 min. The volume (water displacement method) and weight of the brain were measured. The brain was cut coronally and the structures of hippocampus were compared morphologically with those of the pair-matched control. The area of hippocampal formation was measured with paraffin section by test grid under 40x. The mean size (Feret's diameter) of pyramidal neurons in CA1 region was measured with semithin section by ocular micrometer under 1000x. The areal fraction of several organelles of the CA1 pyramidal cells was measured with EM negative film by magnifier. Under conditions of the consistent reference space, especially the size of CA1 pyramidal cells, the areal fraction of rough endoplasmic reticulum, lysosome and mitochondria increased significantly (P < 0.05) in epileptic rats. It indicated that their volume increased. The results show that certain ultrastructural changes have taken place after seizuring for 60 min.

Animals↗
PubMed1996

[A cohort study on the relationship between standardized mortality of pulmonary heart disease and smoking].

We explored the relationship between the standardized mortality of pulmonary heart disease (PHD) and smoking at Shifang county through a five-year follow-up study of 29,498 farmers over 35 years old. The death ratio of PHD was 30.35%, which stood first in all causes of death. The mortality of PHD for cigar/cigarette smokers regardless of sex was not significantly different from that for nonsmokers (P > 0.05). The RR was 1 or so. The analysis of data stratified by age showed that the specific mortality increased with age in spite of some inequalities smoking; the RR of PHD for cigar/cigarette smokers in all age groups were 1 or so revealing no significant differences (P > 0.05). However, the standardized mortality of PHD increased with the accumulated amount of smoking. The relationship between the mortality of PHD and short-term smoking with small dose was not significant (P > 0.05), but when the accumulated amount reached certain level, i.e. the smoker consumed cigar more than 270 kg or consumed cigarette more than 20,000 packs, the relationship between the behavior of cigar/cigarette smoking and the mortality of PHD became apparent. The RRs were 1.40-3.94 and the ARs 171-1610 per 100,000 person years (P < 0.05-0.01).

Adult↗
PubMed1996

[Expression of myelin basic protein gene in the developing human brain].

The expression of myelin basic protein (MBP) gene in the developing human brain was studied by using Northern dot blot and in situ hybridization with 32P- and biotin-labeled rat MBP cDNA and Diglabeled human MBP cRNA probes so as to explore the relation of temporal and spatial expression of human MBP gene to myelinogenesis and myelination. The results of dot blot analysis showed that the expression of MBP mRNA was near 2.0 A590/microgram of RNA in the fetal brain at 16 weeks of conceptional age, and it increased progressively with development to have 9-fold increment (18 A590/microgram of RNA) in the adult brain. The insitu hybridization was performed with the sections of fetal spinal cord and medulla oblongata at 8-25 weeks of conceptional age, and of pons, midbrain, thalamus, cerebellum and cerebrum at 20, 22 and 25 weeks. The results indicated that the expression of MBP mRNA was found as early as 8-9 weeks and localized within the perinuclear cytoplasm of the scattered cells in the ventral horn of spinal cord and near the basis of the fourth ventricle of medulla oblongata. Whether the above-mentioned labeled cells are neurons or precursors of glial cell remains to be identified because they are larger in size and have more abundant cytoplasm than oligodendrocytes. The labeling of MBP mRNA abruptly increased and spread with the processes of oligodendrocytes to form a network in spinal cord and medulla at 20 weeks; meanwhile, labeling was obvious in pons and scattering in the other brain regions examined.

Adult↗
PubMed1996

[The therapeutic effect of somatostatin on acute severe pancreatitis: a clinical contrastive observation].

We observed the effect of somatostatin on the treatment of acute severe pancreatitis and on the inhibition of pancreatic secretion. 21 patients with acute severe pancreatitis were divided into control group (n = 12) and treatment group (n = 9) according to the admission time from 1992 to 1995. The control group was treated regularly and the treatment group was given intravenous somatostatin within 24h of onset 6mg/day for 5-7 days besides the regular treatment. No significant difference was noted in the general conditions of the two groups on admission. The volume of stomach suction in the somatostatin treated group was lower than that in the controls on the 2nd, 3rd and 4th admission days (P < 0.05). The serum amylase level of the treatment group was lower than that of the controls. 12 complications occurred in the somatostatin treated group as compared with 17 in the control group (P > 0.05). The clinical cure time was 15.6 +/- 4.8 days for the treatment group and 21.5 +/- 7.6 days for the controls (P = 0.02). We consider that as a pancreatic secretion inhibitor somatostatin can control the disease process and shorten the clinical cure time to some extent if it is used on the early stage of acute severe pancreatitis.

Adult↗
PubMed1996

[Detection of rpoB gene mutation in Mycobacterium tuberculosis by PCR "cold" SSCP].

OBJECTIVE: To evaluate the applicability of detection of rpoB gene mutation in M. tuberculosis susceptibility testing. METHODS: 87 M. tuberculosis isolates and 22 sputum specimens from patients with active pulmonary tuberculosis were detected by PCR-SSCP. RESULTS: The sensitivity of PCR for rpoB gene amplification was 100 pg DNA and 5000 organisms. The rpoB gene could be detected in the all isolates tested. In comparison with conventional susceptibility testing methods, the sensitivity and specificity of PCR-"cold" SSCP analysis for detecting rifampin resistance in 87 M. tuberculosis isolates was 89.6% and 100%, respectively. Among 22 smear- and culture-positive sputum specimens, only 1 (4.5%) was positive by PCR, however, 6 (27.3%) of them were positive by nested-PCR. The "cold" SSCP results of these 6 specimens were corresponding to that of the susceptibility testing. CONCLUSIONS: The PCR-"cold" SSCP described here can easily and rapidly detect rifampin resistance of M. tuberculosis. After increasing the primer specificity and amplification sensitivity, the technique might be used for detection of M. tuberculosis rifampin resistance in clinical specimen directly.

Antibiotics, Antitubercular↗
PubMed1996

[Relationship between INH-resistance and katG mutation in M. tuberculosis].

OBJECTIVE: To investigate the molecular mechanism of INH-resistance and the relationship between INH-resistance and KatG mutations. METHODS: Use the primers designed from the 5' end of the KatG gene to amplify 282bp fragments from INH-susceptible and -resistant M. tuberculosis isolates. Single strand conformation polymorphism (SSCP) for their PCR products were analysed. RESULTS: No katG gene sequence deletion was observed, mutations were detected in 17 of 30 INH-resistant strains and no gene perturbations were shown in 16 INH-susceptible isolates. CONCLUSION: The results suggested that mutation in katG gene was one of the most important INH-resistant mechanisms in M. tuberculosis.

Antitubercular Agents↗
PubMed1995

Determination of polyamines in serum by high-performance capillary zone electrophoresis with indirect ultraviolet detection.

A method for determining polyamines in serum by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was established. The concentrations of polyamines in the sera of six healthy adults were determined and the results were in accordance with those obtained previously by high-performance liquid chromatography (HPLC). However, the CZE method is superior to HPLC in that it has high sensitivity, small sample consumption and easy sample pretreatment.

Adult↗
PubMed1995

Chiral separation by high-speed countercurrent chromatography.

Various parameters involved in the chiral separation of (+/-)-DNB-amino acids were investigated using N-dodecanoyl-L-proline-3,5-dimethylanilide as a chiral selector (CS) and two-phase solvent systems composed of hexane/ethyl acetate/methanol/10 mM hydrochloric acid at various volume ratios. The results indicated that increasing the concentration or net amount of the CS in the stationary phase improves both separation factor (alpha) and peak resolution (Rs). The hydrophobicity of the solvent system also increases the alpha value of the racemate while it affects the peak resolution differently according to the partition coefficient of the racemate. Overall results indicated that the best separation of a racemate will be achieved by applying a high CS concentration in the organic phase while adjusting the hydrophobicity of the solvent system so that the partition coefficient of the racemate falls between 0.6 and 0.8. The peak resolution will be further increased by using a longer and/or greater internal diameter coiled column.

Amino Acids↗
PubMed1995

Cleavage of DNA by N-phosphoryl histidine.

DNA cleavage by N-(O,O-diisopropyl)phosphoryl histidine(DIPP-His) is investigated by a submarine agarose electrophoresis technique. It was found that DIPP-His could cleave supercoiled DNAs and lambda DNA without the participation of divalent metal ions, while the histidine itself and N-(O,O-diisopropyl)phosphoryl alanine had no such function. Supercoiled pUC8 and pBR322 DNAs are cleaved to linear DNA and eventually fragments; lambda DNA is cleaved directly to fragments. Two mechanistic pathways are proposed for the cleavage reaction.

Bacteriophage lambda↗
PubMed1995

Quantitative determination of serum iron in human blood by high-performance capillary electrophoresis.

A capillary electrophoretic (HPCE) method that can be used to quantitatively determine trace amounts of iron has been developed and applied to determine the iron level in human serum. After precipitation of serum proteins, Fe(III) in the serum is reduced to Fe(II) with hydroxylamine hydrochloride, and a stable Fe(II)-1,10-phenanthroline complex is formed by adding 1,10-phenanthroline to the supernatant containing 2.5 mM ammonium acetate-acetic acid at pH 5.0. The Fe(II)-1,10-phenanthroline complex, [Fe(C12H8N2)3]2+, has a very strong absorbance at 270 nm (with a molar absorptivity of approximately 9.2.10(4)). By measuring the absorbance of [Fe(C12H8N2)3]2+ at 270 nm, the iron level in human serum can be precisely quantified. The interference from copper, a major interference in serum, can be totally eliminated due to the complete separation of [Fe(C12H8N2)3]2+ and the Cu(II)-1,10-phenanthroline complex. In addition, other problems that usually occurred with conventional spectrophotometric methods, such as co-precipitation and occlusion of iron during sample pretreatment, are significantly minimized due to the ability to wash the precipitate and the higher detection sensitivity. With this method, a single drop (10 microliters) of serum would be sufficient to determine the serum iron concentration. The method is reliable, sensitive, rapid and reproducible. Thus it is highly suitable for use in the clinical laboratory.

Electrophoresis, Capillary↗
PubMed1995

Resolution of gram quantities of racemates by high-speed counter-current chromatography.

Gram quantities of (+/-)-dinitrobenzoyl amino acids were separated by high-speed counter-current chromatography (CCC) using N-dodecanoyl-L-proline-3,5-dimethylanilide as a chiral selector (CS). Standard and pH-zone-refining CCC techniques were compared. By using the standard technique, 10 mg to a maximum of 1 g of samples was resolved in 2-9 h simply by increasing the concentration of the CS in the stationary phase. By using pH-zone-refining CCC, even more sample (2 g) was efficiently separated in less time (3 h). In both techniques, leakage of CS from the column was negligible. The method requires no solid support and the same column can be used repeatedly to separate a variety of enantiomers by dissolving appropriate chiral selectors in the stationary phase.

Amino Acids↗
PubMed1995

Functional characterization of the RNA-binding domain and motif of the double-stranded RNA-dependent protein kinase DAI (PKR).

The double-stranded (ds) RNA-activated protein kinase, DAI (also known as PKR), contains an RNA-binding domain comprising two tandem repeats of a motif, the dsRBM, which is shared with a number of other proteins that interact with structured RNAs. We have expressed the entire domain and the first copy of the motif in Escherichia coli and purified the two proteins, p20 and p10, to apparent homogeneity in order to study their interactions with RNA and with the intact kinase enzyme. Both p20 and p10 bound preferentially to structured RNA molecules. Competition assays showed that in both cases the order of affinity is dsRNA > VA RNA > tRNA, but the isolated motif bound much less tightly than the entire domain. Measurement of the dissociation constants for dsRNA by quantitative gel mobility shift analysis gave apparent Kd values of 4 x 10(-9) M and 3.8 x 10(-7) M for p20 and p10, respectively. The binding of p20 molecules to dsRNA appeared to be cooperative. Multiple complexes were formed between the intact domain and dsRNA, saturating at a density of about one p20 molecule/11.25 base-pairs (or one turn) of duplex, whereas p10 achieved only about half of this packing density. The apparent Kd for the p20-VA RNA interaction was estimated as 3.5 x 10(-7) M and at least three complexes were detected, but no distinct complexes were visualized for the interaction between p10 and VA RNA. Both p20 and p10 inhibited autophosphorylation of intact DAI, probably by binding the dsRNA activator. Once activated, DAI could phosphorylate both p10 and p20, suggesting that intermolecular phosphorylation can occur.

Amino Acid Sequence↗
PubMed1995

Separation of peptide derivatives by pH-zone-refining counter-current chromatography.

pH-Zone-refining counter-current chromatography was applied to the preparative separation of oligopeptide derivatives containing up to three amino acids. Both acidic benzyloxycarbonyl peptides and basic peptides-beta-naphthylamide were successfully separated with two-phase solvent systems composed of methyl tert.-butyl ether, 1-butanol, acetonitrile and water using a set of suitable retainer and eluent reagents for each group. The preparative ability of the method was demonstrated in the separation of multigram quantities of analyte with a standard separation column with a total capacity of 325 ml. The effects of important factors such as polarity of the two-phase solvent system, concentrations of the eluent base and the retainer acid were discussed.

Amino Acid Sequence↗