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Biomedical subjects

Y Gao

Publications and source records attributed to Y Gao.

At least 181 records · Page 10Linked to original sources
PubMed2000

[Management of micrognathia deformity associated with obstructive sleep apnea syndrome by distraction osteogenesis].

OBJECTIVE: To review the early results of lengthening of the mandible by distraction osteogenesis for the correction of micrognathia deformity and treatment of the obstructive sleep apnea syndrome (OSAS) simultaneously. METHODS: 5 cases with micrognathia deformity associated with OSAS resulted from unilateral/bilateral temporomandibular joint ankylosis had undergone mandibular distraction osteogenesis. In all of the patients intraoral device was employed. Cephalometric radiographs and polysomnograms were obtained preoperatively and postoperatively. RESULTS: The average distraction distance was 15.28 mm (range 8.5 mm to 24.4 mm). The micrognathia deformity was corrected effectively, at the mean time the incapacious pharyngeal airway was ameliorated. The patients' Apnea Index (AI) had been decreasing, SaO(2) during sleep had got to rise. CONCLUSIONS: Compared with the traditional surgery for the micrognathia associated with OSAS, the technique of mandibular distraction osteogenesis has the advantages of avoiding bone grafting and donor side morbidity, expanding the surrounding soft tissue concurrently, reducing the extent of operation and stability of the treatment effects.

Adolescent↗
PubMed2000

[Surgical treatment of left main stenosis in coronary artery disease].

OBJECTIVE: To study the efficacy of surgical treatment in the patients with left main stenosis of 50% or more. METHODS: Forty-two patients with left main stenosis (LMS) underwent coronary artery bypass grafting (CABG). Their mean age was 68.7 years. 16 patients had 50% to 75% LMS and 26 patients more than 75%. Twenty-nine patients had unstable angina. Seventeen patients with angina were in class III according to CCSS and 18 were in class IV. Preoperative left ventricular ejection fraction in 24 patients was beyond 50%. RESULTS: The mean preoperative hospital stay was 2.3 days. The mean number of grafts was 3.3 per patient. There was no operative death. The patients were all free from angina postoperatively. The mean follow up time was 42 (3 to approximately 78) months without death. CONCLUSIONS: Coronary artery bypass grafting is the first choice to treat left main stenosis. It is a safe and effective method. To determine properly the time of surgical intervention is helpful to reduce preoperative cardiac affairs and improve operative efficacy.

Aged↗
PubMed2000

[A case-control study on the relationship between abnormal homocysteine metabolism and essential hypertension].

OBJECTIVE: To examine the relationship between abnormal homocysteine metabolism and essential hypertension in a Chinese population, a community-based case-control study was conducted. METHODS: 127 essential hypertensive patients aged 35 to 75 were randomly selected from a community. Another 170 control subjects with blood pressure < 140/90 mmHg were selected from the same community. Serum homocysteine was determined using HPLC. Folate and vitamin B(12) were measured by radioimmunoassay. MTHFR genotypes were identified by PCR and restriction fragment length polymorphism analysis with Hinf I digestion. RESULTS: After adjusting for age and sex, the mean homocysteine level was 10.56 micromol/L for hypertensive patients and 10.34 micromol/L for controls (F = 0.234, P = 0.63). No association between either SBP or DBP and Hcy concentration was found in subjects without anti-hypertensive medications. The prevalence of homozygousity for thermolabile MTHFR variant for this population was 13.1%, and the mutant allele frequency was 38.7%. There was no significant difference on genotype distributions and the mutant allele frequency for the two studied groups. However, the concentrations of folate and B(12) for the hypertensive subjects were generally higher than the controls. CONCLUSIONS: The present study did not discover that the elevation of Hcy levels or MTHFR mutation were independent risk factors for essential hypertension. The higher folate and B(12) in the hypertensive subjects might contribute to a lower risk.

Adult↗
PubMed2000

[An genetic epidemiology study of MTHFR gene and blood level (sibpair linkage analysis)].

OBJECTIVE: To explore the relationship between MTHFR gene and blood pressure. METHODS: A total of 142 sibpairs were collected from rural communities of CCPACH. MTHFR gene genotypes were determined by an assay based on the polymerase chain reaction. Phenotype of this study was the level of blood pressure. Covariates were measured by questionnaire, physical examination and clinical indices. Sibpair linkage analysis was used to analyse data by SAGE software. RESULTS: In this study, prevalence of TT genotype of MTHFR gene was 9.3%, while CT was 41%. There was no evidence for linkage of the MTHFR gene with either systolic or diastolic blood pressure identified. CONCLUSION: In our study population, MTHFR gene did not seem to be not related to blood pressure.

Adult↗
PubMed2000

[Effects of hypoxia alone or exercise combined on capillarization of rat gastrocnemius muscle and its mechanism].

OBJECTIVE: To study the effects of hypoxia and hypoxia-combined-exercise on capillary density and vascular endothelial growth factor (VEGF) and its receptor KDR of skeletal muscle in rats. METHODS: Myosin-ATPase histochemistry was used to assay the size and capillary density of skeletal muscle. VEGF and its receptor KDR were studied by immunohistochemistry. RESULTS: Five-week hypoxia (simulated 5,000 m altitude) resulted in a decrease in cross-sectional area of skeletal muscle fiber and an increase in capillary density (CD), but the capillary/fiber ratio (C/F) remained unchanged. After 5-week-exercise at high altitude (1 h/d, 6 d/w), the muscle fibers did not undergo atrophy. At the same time, CD and C/F were increased. VEGF protein was found primarily in the matrix between muscle fibers; VEGF receptor-KDR was shown mainly in endothelial cells of capillary. VEGF was more strongly stained in the skeletal muscle of hypoxia-combined-exercise rats than the other two groups. CONCLUSION: Hypoxia itself can not induce neovascularization, while hypoxia-combined-exercise rats show capillary proliferation in skeletal muscle. VEGF and its receptor might play roles in this process.

Animals↗
PubMed2000

[The devitalization of tumor suppressor genes in oral squamous cell carcinoma].

OBJECTIVE: To study the expression of anti-oncogenes nm23, P16, P53 of squamous cell carcinoma within one sample. METHODS: A total of 27 cases of oral squamous cell carcinoma came from our the First Clinical College, China Medical University from 1997 to 1998, and none of them had the history of radioactivity therapy or chemical therapy. In them, 8 cases were in the early period, and 19 cases were in the late period. 15 cases were male and 12 cases were female. The samples were fixed in formaldehyde solution, embedded with paraffin, sliced in 5 microns, and analysed by ABC immunohistochemistry staining. The first antibodies were anti-P16, anti-nm23, anti-P53 respectively. The criteria of judgment were the following: For nm23, the case that cytoplasm or nucleus were buffy particles or ball was positive. For P16, the case that nucleus were brown was positive, while the case with the light brown cytoplasm and unstained nucleus was negative. The stained nucleus of interstitial cells were treated as the control. For p53, the positive protein product was assembled in the carcinoma cell nucleus, so the nucleus with buffy or brown particles was positive. According to the criteria, 5 high power sights were selected from each case, more than one hundred cells were counted. The case that the positive cells was more than 30 percentage was high expression, and less than 30 percentage was low expression. Two doctors completed the procedure respectively, and only the same results could be qualified. RESULTS: In the 27 cases, the devitalization of nm23 and p16 was showed in low expression, p53 in high expression. The devitalization rate: p16 was 66.7%, nm23 was 48.1%, and p53 was 25.9%. In 14 cases, combined mutation of two inhibitory genes were seen. 9 cases were p16 and nm23, among them, 4 cases had transferred to cervical lymph nodes (In all the cases, there were 6 cases who had cervical lymph node transference). CONCLUSION: p16 genetic changes are more often detected in oral squamous cell carcinoma than the other genetic changes; In a large portion of cases, there were combined genetic changes instead of single gene mutation.

Adult↗
PubMed2000

[A study on the clinical classification of oral submucous fibrosis].

OBJECTIVE: To increase the positive rate and sensitivity of the diagnosis for oral submucous fibrosis (OSF). METHODS: A general oral survey of 11,046 persons was carried out in Xiangtan, Hunan. According to Pindborg's diagnostic standard to epidemiological studies of OSF, 335 cases of OSF were found. The prevalence was 3%. According to different clinical manifestations, 335 cases of OSF were divided into two types: diffuse type and localized type. The cases with typical features of OSF, such as burning pain and discomfort, dryness of the mucosa, progressive inability to open the mouth and presence of palpable bands in the oral mucosa and so on, were in the diffuse type. Those with non-typical features, only having presence of palpable bands in the oral mucosa, were in the localized type. 72 cases were followed-up for ten years. RESULTS: 335 cases of OSF were divided into two types. 13 cases (3.9%) were in the diffuse type, and 322 cases (96.1%) were in the localized type. Most of the OSF in this region belonged to the localized type. It was also discovered that without proper treatment, the subjects sticked to one type of OSF without changing from one type to another after ten years of follow-up. CONCLUSION: Localized type of OSF is the major type of OSF in Xiangtan. It is an independent clinical type. To classify OSF, it is good for the clinicians to pay attention to non-typical OSF. If the non-typical OSF cases are taken into consideration, the prevalence of OSF will increase considerably.

China↗
PubMed2000

[A study on the chemical components of essential oil of oak moss concrete by gas chromatography/mass spectrometry].

The essential oil of oak moss concrete was extracted by volatile oil content equipment. The chemical compositions and their relative contents were analyzed by GC and GC/MS. A Supelco-5 fused silica capillary column (30 m x 0.32 mm i.d.; 0.25 micron thickness) and a flame ionization detector (FID) were employed in GC analysis. The temperature program included temperature increase of 4 degrees C/min from 50 degrees C to 250 degrees C, and a 10 min isothermal period at 250 degrees C. Mass spectra were obtained by electron impact at 70 eV and a source temperature of 170 degrees C. Twenty-four volatile compounds of oak mass concrete were identified, which comprised more than 83% of volatile fraction. The major components were diethyl phthalate, alpha-terpineol, cedrane and linalool.

Acyclic Monoterpenes↗
PubMed2000

[Analysis of headspace constituents of Gardenia flower by GC/MS with solid-phase microextraction and dynamic headspace sampling].

The headspace constituents of fresh Gardenia flower were investigated by GC/MS. The headspace volatiles were sampled by solid-phase microextraction (SPME) and dynamic headspace sampling (DHS). SPME sampling was conducted with 100 microns PDMS fiber at 28 degrees C for 60 min. In DHS sampling, purified nitrogen was used as purging gas with a flow rate at 80 mL/min for 120 min. Tenax GR(20 mesh-40 mesh) was used as adsorbent and the volatiles were eluted by ether, and concentrated to 0.5 mL for GC/MS analysis. A Supelco-wax capillary column (30 m x 0.25 mm i.d. x 0.25 micron df) was employed in GC/MS analysis. Initial oven temperature was kept at 45 degrees C for 2 min, then raised to 250 degrees C at 4 degrees C/min, and kept at 250 degrees C for 10 min. According to SPME-GC/MS analysis, the main compounds in headspace of fresh Gardenia flower included farnesene(64.86%), cis-ocimene(29.33%), linalool(2.74%), cis-3-hexenyl tiglate(1.34%), methyl benzoate(0.25%). Results obtained from SPME and DHS sampling were also compared. In this study, SPME afforded a simpler and more sensitive sampling method, and much more accurate information about headspace volatiles of Gardenia flower.

Acyclic Monoterpenes↗
PubMed2000

[Preparation and characterization of McAbs against lactate dehydrogenase of Plasmodium falciparum].

OBJECTIVE: To prepare and characterize the monoclonal antibodies(McAbs) against lactate dehydrogenase of the Plasmodium falciparum(LDHp). METHODS: BALB/c mice were immunized with purified recombinant LDHp and McAbs against LDHp were prepared according to the protocol of hybridoma technique. The McAbs were characterized by ELISA and Western blot analysis. RESULTS: Two McAbs against LDHp antigen were obtained. Both McAbs were IgG2b. The titer of two McAbs(2A5, 1H10) in the ascites was 1:25,600 and 1:12,800, and in supernatant were 1:512,1:256 respectively. The result of ELISA indicated that two McAbs reacted only with P. falciparum, and did not react with normal human red blood cells, P. vivax, Toxoplasma gondii, Schistosoma japonicum. It is recognized 33 kDa protein which was defined as LDHp by Western blot analysis. CONCLUSION: Two hybridoma cell lines secreting high titer of McAbs against LDHp with high specificity were established.

Animals↗
PubMed2000

[Areas of brain involved in immunoregulation].

OBJECTIVE: To study the location of brain areas involved in immunoregulation. METHODS: Immunohistochemistry and immunofluorescence were used to detect the different distribution of cytokines immunopositive cells in the brain of rats immunized via both intraperitoneal and subcutaneous injections. RESULTS: The cytokines immunopositive cells were distributed in the supraoptic (SO) and paraventricular (PV) nuclei of the hypothalamus, the anterior hypothalamic (AH) nucleus, arcuate and median eminence, the lateral hypothalamic nucleus (LH) and the amygdaloid nuclear complex while only the appearance of the cytokines immunopositive cells in LH and amygdaloid nuclear complex in hypothalamus was related with immunization status of the animals. Double-labelling results showed that the cytokines immunopositive cells were neurons. CONCLUSIONS: We have observed that neurons of the LH and amygdaloid nuclear complex in hypothalamus as a main source of the neuroimmunoregulation played a key role in neuroimmunoregulation and they participated in the neuroimmunoregulation at an early stage of the immune response.

Amygdala↗
PubMed1999

Phosphatidylinositol-4,5-bisphosphate mediates the interaction of syndecan-4 with protein kinase C.

Recent studies have demonstrated that the cytoplasmic tail of syndecan-4, a widely expressed transmembrane proteoglycan, can activate protein kinase Calpha in vitro, in combination with phosphatidylinositol-4,5-bisphosphate (PI-4,5-P(2)). Syndecan-4 is involved in growth factor binding as well as in adhesion to extracellular matrix proteins, while PI-4,5-P(2) synthesis is modulated by growth factor and adhesion-generated signaling. The cooperative activation of PKCalpha by the proteoglycan and the phosphatidylinositol may constitute, therefore, an essential part of the cell's response to these extracellular signals. To characterize the activation mechanism of PKCalpha, we addressed here the nature of the interplay between syndecan-4, PI-4,5-P(2), and PKCalpha by measuring their mutual binding affinities and the specificity of their interactions. We found that the cytoplasmic tail of syndecan-4 is unlikely to bind directly to PKCalpha, and that this interaction critically depends on PI-4,5-P(2). The PI-4,5-P(2) specificity of the activation of PKCalpha is conferred by the cytoplasmic tail of syndecan-4, which has higher binding affinity for this phosphatidylinositol over phosphatidylinositol-3,4-bisphosphate and the -3,4,5-trisphospate. The activation is specific to PKCalpha and does not encompass the novel protein kinase C delta isoenzyme.

Binding Sites↗
PubMed1999

Enhancement of endothelial cell migration and in vitro tube formation by TAP20, a novel beta 5 integrin-modulating, PKC theta-dependent protein.

Migration, proliferation, and tube formation of endothelial cells are regulated by a protein kinase C isoenzyme PKCtheta. A full-length cDNA encoding a novel 20-kD protein, whose expression was PKCtheta-dependent, was identified in endothelial cells, cloned, characterized, and designated as theta-associated protein (TAP) 20. Overexpression of TAP20 decreased cell adhesion and enhanced migration on vitronectin and tube formation in three-dimensional culture. An antiintegrin alphavbeta5 antibody prevented these TAP20 effects. Overexpression of TAP20 also decreased focal adhesion formation in alphavbeta3-deficient cells. The interaction between TAP20 and beta5 integrin cytoplasmic domain was demonstrated by protein coprecipitation and immunoblotting. Thus, the discovery of TAP20, which interacts with integrin beta5 and modulates cell adhesion, migration, and tube formation, further defines a possible pathway to angiogenesis dependent on PKCtheta.

Amino Acid Sequence↗
PubMed1999

The interface between caldesmon domain 4b and subdomain 1 of actin studied by nuclear magnetic resonance spectroscopy.

The ability of caldesmon to inhibit actomyosin ATPase activity involves the interaction of three nonsequential segments of caldesmon domain 4 (amino acids 600-756) with actin. Two of these contacts are located in the C-terminal half of this region of caldesmon which has been designated domain 4b (658-756). To investigate the spatial relationship between the two sites and to determine whether their corresponding contacts on actin are sequentially distinct, we have used NMR spectroscopy to compare the actin binding properties of the minimal inhibitory peptide LW30 comprising residues 693-722 with those of the recombinant domain 4b constructs 658C (658-756) and Cg1 (a mutant of 658C in which the sequence (691)Glu-Trp-Leu-Thr-Lys-Thr(696) is changed to Pro-Gly-His-Tyr-Asn-Asn). Cg1 retains dual-sited actin attachment but displays lowered actin affinity. In the presence of tropomyosin, domain 4b-actin contacts were stronger but not qualitatively different, indicating that tropomyosin affected the conformational equilibrium of caldesmon binding. Simultaneous dual-sited attachment of domain 4b to actin is enabled by the conformational properties of the site-spanning sequence common to 658C, Cg1, and LW30 as reflected in the corresponding NOE and other NMR spectral parameters. A backbone turn region ((713)Gly-Asp-Val-Ser(716)) preceded by an extended segment (Ser(702)-Pro-Ala-Pro-Lys-Pro) acts to constrain the relative disposition of the flanking actin contact sites of domain 4b. In tests with a library of actin peptides, only the C-terminus, 350-375, bound to 658C and LW30. The use of Cu(2+) as a paramagnetic spectral probe bound to the unique His-371 provided evidence of a well-defined geometry for the complex between LW30 and actin residues 350-375 with the N-terminal, site B of domain 4b close to the C-terminal residues of actin. The data are discussed in the context of the potentiation of inhibitory activity by tropomyosin.

Actins↗
PubMed1999

Dictionary building via unsupervised hierarchical motif discovery in the sequence space of natural proteins.

Using Teiresias, a pattern discovery method that identifies all motifs present in any given set of protein sequences without requiring alignment or explicit enumeration of the solution space, we have explored the GenPept sequence database and built a dictionary of all sequence patterns with two or more instances. The entries of this dictionary, henceforth named seqlets, cover 98.12% of all amino acid positions in the input database and in essence provide a comprehensive finite set of descriptors for protein sequence space. As such, seqlets can be effectively used to describe almost every naturally occurring protein. In fact, seqlets can be thought of as building blocks of protein molecules that are a necessary (but not sufficient) condition for function or family equivalence memberships. Thus, seqlets can either define conserved family signatures or cut across molecular families and previously undetected sequence signals deriving from functional convergence. Moreover, we show that seqlets also can capture structurally conserved motifs. The availability of a dictionary of seqlets that has been derived in such an unsupervised, hierarchical manner is generating new opportunities for addressing problems that range from reliable classification and the correlation of sequence fragments with functional categories to faster and sensitive engines for homology searches, evolutionary studies, and protein structure prediction.

Amino Acid Motifs↗
PubMed1999

Localization of the PAK1-, WASP-, and IQGAP1-specifying regions of Cdc42.

The Rho family small GTPase Cdc42 transmits divergent intracellular signals through multiple effector proteins to elicit cellular responses such as cytoskeletal reorganization. Potential effectors of Cdc42 implicated in mediating its cytoskeletal effect in mammalian cells include PAK1, WASP, and IQGAP1. To investigate the determinants of Cdc42-effector specificity, we utilized recombinant Cdc42 mutants and chimeras made between Cdc42 and RhoA to map the regions of Cdc42 contributing to specific effector p21-binding domain (PBD) interaction. Site-directed mutants of the switch I domain and neighboring regions of Cdc42 demonstrated differential binding patterns toward the PBDs of PAK1, WASP, and IQGAP1, suggesting that switch I provides essential determinants for the effector binding, but recognition of each effector by Cdc42 involves a distinct mechanism. Differing from Rac1, the switch I domain and the surrounding region (amino acids 29 to 55) of Cdc42 appeared to be sufficient for specific binding to PAK1, whereas determinants outside the switch I domain, residues 157-191 and 84-120 in particular, were necessary and sufficient to confer specificity to WASP and IQGAP1, respectively. In addition, IQGAP1, but not PAK1 nor WASP, required the unique "insert region," residues 122-134, of Cdc42 to achieve high affinity binding. Microinjection of the constitutively active Cdc42/RhoA chimeras into serum-starved Swiss 3T3 cells showed that although preserving PAK1- and WASP-binding activity could retain the peripheral actin microspike (PAM)-inducing activity of Cdc42, interaction with PAK1 or WASP was not required for this activity. Moreover, IQGAP1-binding alone by Cdc42 was insufficient for PAM-induction. Thus, Cdc42 utilizes multiple distinct structural determinants to specify different effector recognition and to elicit PAM-inducing effect.

3T3 Cells↗