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Biomedical subjects

M Yang

Publications and source records attributed to M Yang.

At least 235 records · Page 13Linked to original sources
PubMed1999

Single amino acid substitution of serine82 to asparagine in first intracellular loop of human cholecystokinin (CCK)-B receptor confers full cyclic AMP responses to CCK and gastrin.

To understand molecular basis of Gs coupling to cholecystokinin (CCK)-A and CCK-B receptor subtypes, we examined cAMP responses in three sets of human CCK receptor mutants expressed in human embryonic kidney (HEK)293 cells. Single or double substitutions of the four nonconserved amino acids in the first intracellular loop of the CCK-BR were made with their CCK-AR counterparts to determine which residues are critical in Gs coupling. Single substitution of Ser82 to Asn, produced maximal cAMP responses comparable with the chimeric CCK-BR containing the entire first intracellular loop of the CCK-AR. Two other single substitutions, Leu81 to Arg and Leu85 to Met, produced significant but smaller cAMP responses. Ser82 was further changed into Asp, Thr, or Ala to determine the specificity of this position in Gs coupling by the CCK-BR. Replacements of Ser to Asp or Thr showed significant cAMP increases but the stimulatory effects were smaller than Ser to Asn, whereas Ser to Ala did not enhance any cAMP response to either CCK or gastrin. Finally, CCK-AR reverse mutants were studied to compare them with their corresponding CCK-BR mutants that showed increased cAMP responses. Substitution of CCK-AR residue Arg68 to Leu resulted in a complete loss of cAMP response, whereas Asn69 to Ser or Met72 to Leu showed markedly diminished cAMP responses. These data identify that specific residues in the first intracellular loop of both CCK receptor subtypes are critical for Gs coupling. Substitution of a single residue Ser82 to Asn in the CCK-BR is sufficient to confer full cAMP responses to agonist stimulation.

Adenylyl Cyclases↗
PubMed1999

[The current status of molecular detection of micrometastatic prostate cancer cells].

We summarized and reviewed published reports, including our studies, on the reverse transcription-polymerase chain reaction (RT-PCR) detection of micrometastatic prostate cancer cells in lymph nodes, bone marrow and peripheral blood. Some published data preliminarily suggest that the RT-PCR assay of micrometastatic prostate cancer cells may allow a more accurate assessment of lymph node and bone metastases of prostate cancer, and offer a presurgical prediction of the pathological stage of clinically localized disease. In addition, the RT-PCR assay may have a unique prognostic value in prostate cancer. However, controversy remains over the clinical significance of the RT-PCR assay. This assay could potentially develop into a diagnostic procedure for the clinical decision making in patients with prostate cancer. To establish the clinical significance of the RT-PCR assay, further optimized and standardized RT-PCR assay studies are needed, investigating large populations and involving long-term follow-up for the determination of any association between the results of the RT-PCR assay and specific clinical outcome.

Humans↗
PubMed1999

[Linkage analysis of chromosome 5 and asthma in a Chinese population].

OBJECTIVE: To investigate the linkage between asthma and 5q31-33 in a Chinese population. METHODS: The linkage between microsatellite markers in 5q and asthma and allergy was tested by lod score analysis. RESULTS: The linkage between asthma and 5q31-33 was not confirmed. CONCLUSION: The genes at 5q31-33 are not likely to contribute to inheritance of asthma in this Chinese population.

Asthma↗
PubMed1999

Genetically fluorescent melanoma bone and organ metastasis models.

We report here the establishment and metastatic properties of bright, highly stable, green fluorescent protein (GFP) expression transductants of the B16 mouse malignant melanoma cell line and the LOX human melanoma line. The highly fluorescent malignant melanoma cell lines allowed the visualization of skeletal and multiorgan metastases after i.v. injection of B16 cells in C57BL/6 mice and intradermal injection of LOX cells in nude mice. The melanoma cell lines were transduced with the pLEIN expression retroviral vector containing the GFP and neomycin resistance genes. Stable B16F0 and LOX clones expressing high levels of GFP were selected stepwise in vitro in levels of G418 of up to 800 microg/ml. Extensive bone and bone marrow metastases of B16F0 were visualized by GFP expression when the animals were sacrificed 3 weeks after cell implantation. Metastases for both cell lines were visualized in many organs, including the brain, lung, pleural membrane, liver, kidney, adrenal gland, lymph nodes, skeleton, muscle, and skin by GFP fluorescence. This is the first observation of experimental skeletal metastases of melanoma, which was made possible by GFP expression. These models should facilitate future studies of the mechanism and therapy of bone and multiorgan metastasis of melanoma.

Animals↗
PubMed1999

New buccinator myomucosal island flap: anatomic study and clinical application.

The authors studied the vascular anatomy of the buccinator muscle by dissecting fresh cadavers. The anatomy of the buccal branches of the facial artery consistently confirmed the existence of a posterior buccal branch, a few inferior buccal branches, and anterior buccal branches to the posterior, inferior, and anterior portions of the buccinator. The buccal artery and posterior buccal branch anastomose to each other and ramify over the muscle. Several veins originate from the lateral aspect of the muscle, converge into the buccal venous plexus, and drain into the facial vein (from two to four tributaries) or into the pterygoid plexus and the internal maxillary vein (from the buccal vein). These vessels and nerves enter the posterior half of the buccinator posterolaterally. The facial artery and vein are located at variable distances from each other around the oral commissure and the nasal base. Two patterns of buccinator musculomucosal island flaps supplied by these buccal arterial branches are proposed in this article. The buccal musculomucosal neurovascular island flap (posteriorly based), supplied by the buccal artery, its posterior buccal branch, and the long buccal nerve, can be passed through a tunnel under the pterygomandibular ligament for closure of mucosal defects in the palate, pharyngeal sites, the alveolus, and the floor of the mouth. The buccal musculomucosal reversed-flow arterial island flap (superiorly based), supplied by the distal portion of the facial artery through the anterior buccal branches, can be used to close mucosal defects in the anterior hard palate, alveolus, maxillary antrum, nasal floor and septum, lip, and orbit. The authors have used the flaps in 12 patients. There has been no flap necrosis, and results have been satisfactory, both aesthetically and functionally.

Adult↗
PubMed1999

[Expression of endothelial nitric oxide synthase mRNA in human placenta].

OBJECTIVE: To determine the localization and type of nitric oxide synthase in human placenta. METHODS: By polymerase chain reaction and in situ hybridization. The eNOS mRNA expression was observed in 10 cases of human normal term placenta and cord. RESULTS: In human normal term placenta, positive staining of eNOS was evident in the syncytiotrophoblast and the endothelium of umbilical artery and vein, positive staining also presented in the endothelium of stem villous vessels, but it was absent in the endothelium of terminal villous capillary. CONCLUSION: eNOS is present in syncytiotrophoblast and endothelium of stem villi vessels, and it can synthesize nitric oxide which results in the increase of nitric oxide in pregnancy.

Adult↗
PubMed1999

[A study on the T-cell subsets and glucocorticoid receptor in children with anaphylactoid purpura].

To study the changes of T-cell subsets and glucocorticoid receptor (GCR) in children with anaphylactoid purpura. T-cell subsets and GCR were measured respectively by cytotoxicity assay and GCR radioligand-binding assay in peripheral blood lymphocytes from 35 children with anaphylactoid purpura and 35 normal children. The result showed that the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 46.03% +/- 9.40%, 31.06% +/- 6.80% and 1.23 +/- 0.33 respectively, and the GCR numbered 3060 +/- 2153 binding sites per cell in the study group, on the other hand, the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 53.11% +/- 5.40%, 35.01% +/- 4.41% and 1.52 +/- 0.26 respectively, and the GCR numbered 5210 +/- 1639 binding sites per cell in the control group. These indicate that and that patients with anaphylactoid purpura may have abnormal immunomodulations and decreased GCR numbers per cell, which may have effects on the immune dysfunctions in the pathogenesis of anaphylactoid purpura.

Adolescent↗
PubMed1999

[Pregnancy induced hypertension complicated acute disseminated intravascular coagulation: clinical analysis of 26 cases].

OBJECTIVE: To determine the relationship between pregnancy induced hypertension (PIH) and acute disseminated intravascular coagulation (DIC). METHODS: 26 cases with PIH complicated acute DIC were analyzed retrospectively in five hospitals of Xi'an from 1980 to 1997. RESULTS: (1) In 26 patients with PIH complicated acute DIC, 7 cases died (26.92%), while 17 neonates died (58.62%) in 29 neonates (3 cases were twin pregnancy). Cesarean section and hysterectomy were performed on 7 cases respectively, including 4 cases underwent both of them. (2) The causative factors of PIH complicated acute DIC included placental abruption (7 cases), amniotic fluid embolism (4 cases), eclamptic seizure (4 cases), surgical injury (7 cases) and bleeding (4 cases). 7 cases induced by placental abruption were all cured, 4 cases induced by amniotic fluid embolism all died. CONCLUSION: There are close relationship between PIH and DIC, PIH complicated acute DIC is the major cause of maternal and perinatal mortality, special attention should be paid on preventing DIC for PIH.

Abruptio Placentae↗
PubMed1999

[The scapular free flap crossing the dorsal midline].

OBJECTIVE: A large defect needs a large flap to repair. This clinical study was to explore the possibility and safeness of transferring the extended scapular free flap. METHOD: We have used the transverse scapular flap to reconstruct large defects in the mandibular or cervical region in 8 patients. The flap was designed to cross the midline of the back as far as 15 cm. The largest flap measured 31 x 34 cm. RESULTS: Of the 8 flaps, six survived completely; local epidermal necrosis appeared in two. CONCLUSION: The free scapular flap supplied by a single circumflex scapular vascular pedicle can be safely extended beyond the midline of the back. The flap axis is the horizontal branch of the circumflex scapular vessel.

Adolescent↗
PubMed1999

[The periareolar incision technique for reduction mammoplasty].

OBJECTIVE: A technique is introduced to reduce the scar of classic reduction mammoplasty. METHODS: Two concentric circles were designed with the nipple in the centre. The skin between the two circles was deepithelized. Then the glandular tissues situated mainly in the lateral superior quadrant are resected. Finally, round block suturing is made. Eight patients were operated on with this method. RESULTS: The operative results were satisfactory with inconspicuous periareolar scar. CONCLUSION: Periareolar round block reduction mammoplasty is a simple, practical and easy method.

Adult↗
PubMed1999

Preliminary studies on tin miners' lung cancer tissue related genes by differential display mRNA.

OBJECTIVE: To study the genes related to tin miners' lung cancer tissue. METHOD: Differential display mRNA. RESULTS: Thirty cDNA fragments which differentially expressed in lung cancer tissues and the same patient's normal lung tissues were discovered. Among these, 16 expressed in lung cancer tissues, not in normal lung tissues; fourteen expressed on the contrary. Six cDNA fragment sequence was determined. Five sequences CG2, CG7, CG8, CA5 and CC6 had less than 75% homology with known sequences in GenBank BLAST, so they were believed to be new sequences which we have recorded in Genbank. Only one fragment coded CG3 had homology up to 95% with human ribosome protein L27a gene. CONCLUSIONS: mRNA differential display provides a unique and powerful experimental system to study differential gene expression in tin miners' lung cancer tissues and the same patient's normal lung tissues. Using the system, differential expression of 30 cDNA fragments was observed. Six of them may be used to study the molecular mechanism of miners' radon-associated lung cancer.

Adenocarcinoma↗
PubMed1999

[The causes of chylous ascites: a report of 22 cases].

OBJECTIVE: To review the causes and test the diagnostic accuracy of chylous ascites in 22 cases hospitalized in recent years and to compare the efficacy of current investigative procedures with those of previous decades. METHODS: 22 patients with chylous ascites were studied; they were admitted into Peking Union Medical College Hospital in 7 years (1990 - 1997). The data of the 22 patients were compared with those of 17 cases in previous 67 years (1923 - 1989) in the same hospital. Twelve of 22 patients underwent (99)Tc-labeled lymphoscintigraphy. RESULTS: Chylous ascites was diagnosed by ascites in all the 22 patients with analysis of ascitic fluid. Otherwise, the diagnosis would not be established in eight cases if examined with the naked eye. The causes of all the 22 cases were clearly diagnosed. However, the causes were not known in five cases in the 17 cases of previous years. The main causes in this group were malignant tumors (6/22), hepatic cirrhosis (5/22) and tuberculosis (4/22). Other causes included traumatic and congenital lymphatic lesions. CONCLUSION: The causes of chylous ascites can be made clear and definite by detailed comprehensive examinations, including scintigraphy. The main causes were malignant tumor, hepatic cirrhosis and tuberculosis.

Adolescent↗
PubMed1999

[Morphological cure of cerebral arteriovenous malformations by endovascular therapeutics].

OBJECTIVE: To sum up the clinical characteristics and typical manifestation by analysing clinical materials from total embolized cerebral arteriovenous malformations (AVM) via endovascular embolization. METHODS: We reviewed clinical and image materials of 50 patients whose cerebral AVM were embolized entirely and found the cerebral AVM morphological cure by endovascular embolization after studying the size, position, artery supply, therapeutics and follow-up. RESULTS: 50 patients with cerebral AVM were embolized by endovascular therapy, accounting for 17% of all patients. Malformation lesions were medium or small type, with a diameter less than 3 cm, 95% of them were located in the tentorium superior. Terminal end blood supply was common to AVM and especially medium cerebral artery (MCA) or its branches. 97% of the patients were graded III or below by spectzler grading system. 70% of them had a history of intracranial hemorrhage and were cured by one therapy. CONCLUSIONS: It is a reliable and feasible method for morphological cure in cerebral AVM via endovascular therapeutics only, but case selection is important, that is, medium or small AVM with single branch terminal end blood supply in the tentorium superior.

Adolescent↗
PubMed1999

[Isolation, purification and antibacterial activities of salivary histidine-rich polypeptides].

OBJECTIVE: To isolate and purify salivary histidine-rich-polypeptides (HRPs) and observe their antibacterial activities. METHODS: By using of preparative acid urea polyacrylamide gel electrophoresis (AU-PAGE), three major HRPs(HRP-1, HRP-3 and HRP-5) were purified from parotid saliva collected from healthy adults. Their antibacterial activities were tested in the ultrasensitive antibacterial assay, named radial diffusion assay. RESULTS: Each fraction of the three purified HRPs appeared as a single protein zone both in AU-PAGE and Tricine-SDS-PAGE. Their molecular weights are 3-5 kD as determined by Tricine-SDS-PAGE. All the three major HRPs showed potent bactericidal effects on Streptococcus mutans MT6R and Staphylococcus aureas ATCC25923. As to Escherichia coli ML-35P and Pseudomonas aeruginosa ATCC27853, HRP-3 and HRP-5 also demonstrated significant antibacterial activities, whereas HRP-1 did not show any inhibitory effects on the viability of them. CONCLUSION: The above results suggested that the method of preparative AU-PAGE we used in this study has the benefits of high resolution, simple manipulation and perfect results of purification. HRPs are important components to prevent oral tissue from bacterial infections, therefore play a potent role in the maintenance of the oral health.

Adult↗
PubMed1999

The study on related genes in the neoplastic transformation of immortalized human fetal tracheal fibroblast cells induced by irradiation.

In this study, we investigated the genes related to the transformation of immortalized human fetal tracheal fibroblast cell line induced by alpha particles by means of differential display mRNA method. The result revealed that there were 23 DNA fragments that were expressed intensively in alphaSHTF cells (SHTF cells forming clone on agar after irradiated by alpha particles emitted by 238Pu) only and not in SHTF (SV40-immortalized human fetal tracheal fibroblast) cells. Northern dot confirmed two fragments, C17-5, C23-1 which showed intensive mRNA expression in alphaSHTF cells, but not in SHTF cells. The length of the C17-5 fragment was 310bp. Searching in BLAST database revealed that the C17-5 fragment might be an unknown sequence.

Base Sequence↗
PubMed1999

[Determination of trace aluminium by ETV-ICP-AES].

The effect of mixed halogenation agent (polytrifluorochloroethylene (PTFCE)/hexachloroethane (C2Cl6)) on the vaporization of aluminium has been studied in electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES). The mixed halogenation agent hastens the vaporization of Al to the plasma at low temperature compared with individual halogenation agent, and the metallic material can be prevented affectively from forming in the furnace. The detection limit of this method was 0.12 ng with RSD of 3.8% (Al: 0.3 microg x mL(-1), n = 7). The analytical results of real samples were in good agreement with those of pheumatic nebulization (PN)-ICP-AES, and the recoveries were in the range of 94.1%-102.5%.

English Abstract↗
PubMed1998

Identification of amino acid substitutions that confer a high affinity for sulfaphenazole binding and a high catalytic efficiency for warfarin metabolism to P450 2C19.

Human cytochrome P450s 2C9 and 2C19 metabolize many important drugs including tolbutamide, phenytoin, and (S)-warfarin. Although they differ at only 43 of 490 amino acids, sulfaphenazole (SFZ) is a potent and selective inhibitor of P450 2C9 with an IC50 and a spectrally determined binding constant, KS, of <1 microM. P450 2C19 is not affected by SFZ at concentrations up to 100 microM. A panel of CYP2C9/2C19 chimeric proteins was constructed in order to identify the sequence differences that underlie this difference in SFZ binding. Replacement of amino acids 227-338 in 2C19 with the corresponding region of 2C9 resulted in high-affinity SFZ binding (KS approximately 4 microM) that was not seen when a shorter fragment of 2C9 was substituted (227-282). However, replacement of amino acids 283-338 resulted in extremely low holoenzyme expression levels in Escherichia coli, indicating protein instability. A single mutation, E241K, which homology modeling indicated would restore a favorable charge pair interaction between K241 in helix G and E288 in helix I, led to successful expression of this chimera that exhibited a KS < 10 microM for SFZ. Systematic replacement of the remaining differing amino acids revealed that two amino acid substitutions in 2C19 (N286S, I289N) confer high-affinity SFZ binding (KS < 5 microM). When combined with a third substitution, E241K, the resulting 2C19 triple mutant exhibited a high cataltyic efficiency for warfarin metabolism with the relaxed stereo- and regiospecificity of 2C19 and a lower KM for (S)-warfarin metabolism (<10 microM) typical of 2C9.

Amino Acid Sequence↗