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Biomedical subjects

X Gao

Publications and source records attributed to X Gao.

At least 163 records · Page 9Linked to original sources
PubMed2000

The extent of biopsy involvement as an independent predictor of extraprostatic extension and surgical margin status in low risk prostate cancer: implications for treatment selection.

PURPOSE: We identify predictors of extraprostatic extension and positive surgical margins in patients with low risk prostate cancer (prostate specific antigen [PSA] 10 ng./ml. or less, biopsy Gleason score 7 or less and clinical stage T1c-2b). MATERIALS AND METHODS: From August 1997 to January 1999, 143 previously untreated patients underwent radical retropubic prostatectomy for clinically localized prostate cancer. A total of 62 patients were low risk, with PSA 10 ng./ml. or less, biopsy Gleason score 7 or less and clinical stage T1c-2b, and had sextant biopsy with separate pathological evaluation of each sextant cores. PSA, clinical stage, biopsy Gleason score, average percentage of cancer in the entire biopsy specimen, maximum percentage of cancer on the most involved core, number of cores involved and bilaterality were evaluated for association with extraprostatic extension, seminal vesicle involvement and positive surgical margins. RESULTS: Of the 62 patients 13 (21%) had extraprostatic extension, 6 (10%) seminal vesicle involvement and 20 (32%) positive surgical margins. Average percentage greater than 10% and maximum percentage greater than 25% were associated with extraprostatic extension (p = 0.01 and 0.004, respectively). Average percentage greater than 10%, maximum percentage greater than 25%, more than 2 cores involved and bilaterality were associated with positive surgical margins (p = 0.007, 0.01, 0.002 and 0.03, respectively). On multivariate analysis maximum percentage remained the only independent predictor of extraprostatic extension (p = 0.03), and the number of cores involved remained an independent predictor of positive surgical margins (p = 0.01). Biopsy Gleason score, PSA and clinical stage did not correlate with extraprostatic extension or positive surgical margins in this patient population. CONCLUSIONS: In low risk prostate cancer the extent of biopsy involvement significantly correlates with the risk of extraprostatic extension and positive surgical margins. Biopsy information should be considered when selecting and modifying treatment modalities.

Aged↗
PubMed2000

[Study on preparation and biodistribution of PEG-immunoliposomes with active carboxylic terminals].

AIM: In order to accumulate into its target specifically, the immunoliposomes must possess two characteristics: specific target efficiency to its target cells and prolonged circulation in blood. A new type of polyethylene glycol (PEG)-immunoliposomes carrying monoclonal antibodies at the distal end of PEG chains should be developed. METHODS: A dipalmitoylphosphatidylethanolamine (DPPE) derivative of PEG with carboxyl group (DPPE-PEG3000-COOH) was newly synthesized. Small unilamellar liposomes were prepared from egg phosphatidyl choline and cholesterol (5:4, mol/mol) containing 6 mol% DPPE-PEG3000-COOH using reverse-phase evaporation method followed with bath sonication. Monoclonal antibody of human bladder cancer cell (BDI-1), which is highly specific to human bladder cancer cell, was conjugated to PEG-liposomes as well as mouse IgG at the distal end of polyethylene glycol chain. Doxorubicin was entrapped into these immunoliposomes by remote (NH4)2SO4 gradient loading method. The specific targeting efficiency of these immnoliposomes was tested by cytotoxicity test in vitro, enzyme-linked immune sorbent assay (ELISA) and indirect fluorescent immunoassay. Its biodistribution was carried out in mice. RESULTS: The specific targeting efficiency of BDI-1 immunoliposomes (BDI-1-IML) to EJ cells has been demonstrated, in contrast to the nonspecific human colon carcinoma cells (LOVO). PEG-liposomes linked with mouse IgG (mouse-IgG-immunoliposomes, IgG-IML) displayed lower reticulo-endothelial systems (RES) uptake and longer circulation time than liposomes without PEG after intravenous injection. CONCLUSION: The long circulation of these PEG-immunoliposomes in vivo, combined with its specific targeting efficiency demonstrated in vitro, guarantees the positive targeting efficiency of these immunoliposomes to its target carcinoma in vivo.

Animals↗
PubMed2000

[Study on composition of plaque fluid in individuals with no oral hygiene].

OBJECTIVE: To study the change of composition in long-term plaque fluid after sucrose rinse and the cariogenicity of plaque. METHODS: 43 subjects, who had no regular oral hygiene and no tooth brushing at least for one year, were selected. According to their caries status, 27 as caries-free group and 16 as caries-positive group. Plaque were obtained before and at 7 minutes after a 10% sucrose rinse. Additionally, plaque samples of 15 and 30 minutes after sucrose rinse from 11 subjects were collected. The pH value and the concentrations of organic acids and inorganic ions in plaque fluid were measured. RESULTS: At 7 minutes after sucrose rinse, pH and the concentration of ammonium were significantly decreased, and the concentrations of lactic acid and formic acid were significantly increased. All these changes were similar to those of short-term plaque. No significant difference with any single component of plaque fluid was found between caries-free group and caries-positive group, neither before sucrose rinse nor after sucrose rinse. CONCLUSIONS: Changes of the composition in the plaque fluid were basically similar between long-term and short-term plaque, but single component in plaque fluid could not reflect the cariogenicity of plaque.

Adult↗
PubMed2000

[The dynamics of pH, free calcium and total proteins in root plaque fluid and their relationships to the cariogenic potential].

OBJECTIVE: To enhance knowledge of root caries by analysis of the dynamics of dental plaque fluids on root surface and their relationships with the caries history. METHODS: The pH, free calcium and total proteins of dental plaque fluids on sound root surfaces were analyzed before and after the sucrose challenge. Subjects were either root caries-free (RCF) or caries-positive (RCP). RESULTS: After a sucrose challenge, the pH of plaque fluids dropped significantly and the concentration of free calcium increased significantly. There were no statistical differences in pH (RCF group 6.24 +/- 0.74, RCP group 5.96 +/- 0.70) and free calcium [RCF group (0.60 +/- 0.46) mmol/L, RCP group (0.89 +/- 0.54) mmol/L] between RCF and RCP group before sucrose challenge. Following sucrose exposure, pH (5.14 +/- 0.19) and free calcium [(1.73 +/- 0.74) mmol/L] in RCP group were significantly lower than RCP group [(pH 5.28 +/- 0.16), free calcium (2.73 +/- 1.25) mmol/L]. No interrelationship has been found between the amount of total proteins and free calcium. Components (contents, change trend) in root plaque were strongly related to that in coronal plaque. CONCLUSIONS: The process of root caries may be consistent to coronal caries regarding to the acid production of bacteria after a sucrose challenge. Plaque compositions show a stronger cariogenic potential in RCP group.

Calcium↗
PubMed2000

[A study of fluoride-containing composite resins: fluoride release, water sorption and dissolution].

OBJECTIVE: To study fluoride release and its impact on the basic properties. METHODS: Fluoride releasing was determined by F-electrodes, water sorption and dissolution of the materials were determined by weight/volume loss technique. RESULTS: The profile of fluoride release from fluoride-containing composites was different from that of compomer. Meanwhile, fluoride-containing materials showed larger values of water sorption (13.05-31.64 micrograms/mm3) and dissolution(5.88-24.80 micrograms/mm3) than controls. CONCLUSIONS: The F- releasing may affect physical and mechanical properties of fluoride-containing composites.

Composite Resins↗
PubMed2000

[Diagnosis and surgical treatment of temporal lobe epilepsy].

OBJECTIVE: To discuss the diagnosis and surgical treatment of temporal lobe epilepsy. METHODS: From 1995 to 1998, 30 patients with intractable mesial temporal lobe epilepsy were identified by EEG and MR. Among them, 15 patients underwent anterior temporal lobectomy, while another 15 patients accepted selective amygdalahippocampectomy. The results of operation and follow-up were analyzed. RESULTS: As to seizure outcome, all patients were benefited from surgery. Surgical result was satisfactory in 18 patients, notable in 11, and good in 1. There was no complication. CONCLUSIONS: MR is beneficial for the localization of epileptic foci. Operation is an effective way for the treatment of temporal lobe epilepsy. Selective amygdalohippocampus is the first choice for medial temporal lobe epilepsy. Transzygmatic-temporal lobe base approach improves the safety of operation.

Adolescent↗
PubMed2000

[Effect of green and yellow vegetables on serum carotenoid in children].

OBJECTIVE: To assay the effect of green and yellow vegetables on serum carotenoid concentration and its relation to serum retinol level in children. METHODS: A ten-week green and yellow vegetable intervention study was conducted in children aged 5.3 to 6.4 years of two classes in a kindergarten in Tai'an City of Shandong Province in early September 1996, one class of light-colored vegetable supplemented with daily 193 grams of light colored vegetables, such as cabbage, Chinese cabbage, potato, cucumber, cauliflower and turnip, and 56 grams of yellow-green vegetables, such as spinach, Chinese chive, carrots and red yams; and the other one of yellow-green vegetables with daily 238 grams of yellow-green vegetables and 34 grams of light colored vegetables, both without change in regular diet. Venous blood specimens were collected before and after the experiment from each of the subjects. Serum retinol and carotenoid were determined with high performance liquid chromatography. RESULTS: Serum level of carotenoid, including all-trans-beta-carotene, cis-beta-carotene, cryptoxanthin and lutein were significantly higher after intervention in yellow-green vegetable group, as compared to their baseline levels. However, in the light-colored vegetable group, all those components, including all-trans-beta-carotene, 13-cis-beta-carotene and lutein, decreased significantly after intervention, as compared with those at their baseline levels. Serum carotene level correlated significantly with that of retinol, and their coefficient of correlation was greater in the winter than in the autumn. CONCLUSION: Carotenoid nutrition status can be improved by supplementation of green and yellow vegetables.

Carotenoids↗
PubMed2000

[Ultrastructural and immunohistochemical characteristics of pericytes during neovascularization in breast carcinoma].

OBJECTIVE: To study the morphology of pericyte, the relationship between pericytes and neovascularization of breast carcinoma. METHODS: Ultrastructural, immunohistochemical and quantitative morphology analysis techniques were used to study 89 cases of human breast carcinoma. 4 human granulation tissues cases were used as control. RESULTS: The positive cells for FVIIIRAg were endothelial cells situated inside the vascular wall with abundant cytoplasm containing caveolae and Weibel-palade bodies. The positive cells for alpha-SMA were pericytes with cytoplasm containing abundant myofilament, and connections with endothelial cells. The pericyte-endothelial junctions can be found. Quantitative morphological analysis showed that the number of pericytes in the low-microvascular density areas are much higher than that in the high- microvascular density areas (P < 0.0005). CONCLUSION: Ultrastructural observation and immunohistochemical staining of alpha-SMA are useful in identifying pericytes. The results of this study imply that pericytes may possibly inhibit angiogenesis.

Actins↗
PubMed2000

[Clinical observation on operation of cerebral speech area under combined acupuncture-drug anesthesia].

OBJECTIVE: To study the effect of combined acupuncture-drug anesthesia (CADA) in neurosurgical operation of cerebral speech area. METHODS: Twenty-five patients with tumor close to the speech area underwent neurosurgical operation under CADA or general anesthesia were observed, and the post-operational language function protecting effect was analyzed. RESULTS: Among the 15 patients accepted CADA, total tumor resection was achieved in 9 cases, and subtotal or partial resection achieved in 6 due to their tumor too close to the speech area. No post-operational complication such as dysphasia or aggravation of functional disorder was found in the patients. In the 10 cases underwent general anesthesia, 7 had tumor total resection, 3 had partial resection, and 3 cases suffered from post-operational dysphasia. CONCLUSION: CADA is helpful in speech area judgement in neurosurgical operation so as to avoid the operational injury on functional area. It is an important method of anesthesia in surgical operation on cerebral speech area.

Acupuncture Analgesia↗
PubMed2000

[Thyroidectomy and injury of recurrent laryngeal nerve].

OBJECTIVE: To study factors related to recurrent laryngeal nerve (RLN) paralysis, a major complication of thyroidectomy. METHOD: Retrospective study of outcome of patient's medical records in Xijing Hospital and Tumor Hospital of Liaoning Province. Records of 1,563 patients who underwent thyroidectomy by departments of general surgery, ENT and head & neck surgery at these two hospitals were reviewed for RLN paralysis. MAIN OUTCOME MEASURES: RLN injury was analyzed in relation to types of surgery, RLN identification, and histopathology. RESULT: The incidence of RLN paralysis was 7.8%, and significantly related to the histopathologic findings of malignancy (P < 0.01). The positive identification and prevention of RLN would not be in either permanent RLN paralysis or temporary RLN paralysis, and the types of surgery were not found to be significant factors in both paralysis. CONCLUSION: RLNs should be identified to avoid iatrogenic injury and subsequent paralysis, and meticulous surgical technique should be applied in patients whose results of biopsy suggested malignancy.

Adolescent↗
PubMed2000

[Sequence analyzing and genotyping of the gene encoding glutamate rich protein of geographically different Plasmodium falciparum isolates obtained from different malaria endemic areas].

OBJECTIVE: To sequence a gene encoding GLURP and identify the genotypes of geographically different Plasmodium falciparum isolates from Yunnan and Hainan Provinces, China. METHODS: The gene of R2 repeat region of GLURP was amplified by the nested polymerase chain reaction and cloned into T-vector. The nucleotide sequence of the GLURP gene was determined using automatic sequencer (dideoxy chain termination method), and analyzed by DNA Star software. RESULTS: At least 7 different GLURP genotypes ranging from 600 bp to 1,500 bp were found in different P. falciparum isolates from Yunnan and Hainan Provinces. R2 region of GLURP gene consisted of several repeat units, each was composed of 19-20 residues which were shown to be highly conserved. The GLURP gene was also size polymorphic due to differences in the number of repeat units, whereas the repeat sequence was conserved. Sequence analysis showed that DNA sequences and deduced amino acid sequences were highly homologous among the geographically dispersed isolates or various isolates from the same geographical region. No obvious differences were found in the GLURP gene sequences among geographically different isolates. CONCLUSION: The GLURP gene of geographically different P. falciparum isolates is highly conserved and size polymorphic, being useful in searching for malaria vaccine candidate antigen and developing a genotyping method for malaria research.

Amino Acid Sequence↗
PubMed2000

[Alloreactive helper T cell responses in kidney transplant patients].

OBJECTIVE: To study allo-specific immune responses of CD4+ helper T lymphocytes (Th) in patients with long-term and well-functioning renal grafts. METHODS: Peripheral blood mononuclear cells (PBMC) were collected from 16 patients with long-term (3-15 years) and well-functioning live-related renal grafts. Donor-specific Th precursor (Th-p) frequencies in the PBMC were determined by limiting dilution analysis(LDA). RESULTS: Eight out of the 16 patients showed donor-specific hyporesponsiveness. Donor-specific Th-p from the other 8 patients was susceptible to anti-CD4 inhibition. CONCLUSION: Some of the patients carrying long-term and well-functioning renal grafts had become immunologic tolerant to donor cells. Donor-specific Th-p from patients who did not show donor-specific hyporesponsiveness were of low avidity type.

Adult↗
PubMed1999

RA-GEF, a novel Rap1A guanine nucleotide exchange factor containing a Ras/Rap1A-associating domain, is conserved between nematode and humans.

A yeast two-hybrid screening for Ras-binding proteins in nematode Caenorhabditis elegans has identified a guanine nucleotide exchange factor (GEF) containing a Ras/Rap1A-associating (RA) domain, termed Ce-RA-GEF. Both Ce-RA-GEF and its human counterpart Hs-RA-GEF possessed a PSD-95/DlgA/ZO-1 (PDZ) domain and a Ras exchanger motif (REM) domain in addition to the RA and GEF domains. They also contained a region homologous to a cyclic nucleotide monophosphate-binding domain, which turned out to be incapable of binding cAMP or cGMP. Although the REM and GEF domains are conserved with other GEFs acting on Ras family small GTP-binding proteins, the RA and PDZ domains are unseen in any of them. Hs-RA-GEF exhibited not only a GTP-dependent binding activity to Rap1A at its RA domain but also an activity to stimulate GDP/GTP exchange of Rap1A both in vitro and in vivo at the segment containing its REM and GEF domains. However, it did not exhibit any binding or GEF activity toward Ras. On the other hand, Ce-RA-GEF associated with and stimulated GDP/GTP exchange of both Ras and Rap1A. These results indicate that Ce-RA-GEF and Hs-RA-GEF define a novel class of Rap1A GEF molecules, which are conserved through evolution.

Amino Acid Sequence↗
PubMed1999

The study of the conformation and interaction of two tachykinin peptides in membrane mimicking systems by NMR spectroscopy and pulsed field gradient diffusion.

Pulsed-field gradient diffusion has been used to study the binding of two tachykinin peptides, [Tyr(8)]-substance P (SP) and [Tyr(0)]-neurokinin A (NKA) to two membrane-mimicking micelles, dodecylphosphocholine, and sodium dodecylsulfate. The structure of these peptides bound to the micelles have also been studied by using two-dimensional nmr and restrained simulated annealing calculations. No major difference in the structures of each peptide in the two micellar media was found. The difference between the micelle-bound structure of [Tyr(8)]SP and that of SP was also minor. The longer helical conformation on the C-terminus for [Tyr(0)]NKA was observed, compared with that for NKA. The relationship between the difference in the biological potencies of [Tyr(8)]SP and SP and the differences in their structure, especially the interaction of the side chains of the two aromatic residues, and the difference in their binding affinities to membrane was discussed. In addition, differences between the result of restrained molecular dynamics simulations of [Tyr(8)]SP in the presence of an explicit micelle and the present results were observed and discussed.

Animals↗
PubMed1999

[Evaluation on the nutritional status of carotenoid in healthy elder people].

The possible relations between carotenoid status and their health indicators were investigated in an elderly group aged 60-75 years. Fasting serum samples were taken from 41 healthy subjects (20 men and 21 women). The concentrations of carotenoids and vitamin A of serum samples were assayed by HPLC. The results showed that vitamin A level of seven subjects was lower than 0.3 mg/L. Lutein and Zeaxanthin were the predominant carotenoids in serum. The concentration of total carotenoids had inverse correlations with blood glucose, serum cholesterol and triglyceride, and blood pressure. Carotenoids were inversely and significantly correlated with diastolic pressure and body mass index.

Aged↗
PubMed1999

NMR structure of an antisense DNA.RNA hybrid duplex containing a 3'-CH(2)N(CH(3))-O-5' or an MMI backbone linker.

The solution structure of an antisense DNA.RNA hybrid duplex, d(CGCGTT-MMI-TTGCGC).r(GCGCAAAACGCG) (designated R4), containing an MMI backbone linker [3'-CH(2)N(CH(3))-O5'], is elucidated. The structural details of the MMI linker, its structural effects on the neighboring residues, and the molecular basis of the MMI effects are examined. The lipophilic N-methyl group of MMI is peripheral to the helix, assuming a conformation that is most stable with regard to the N-O torsion angle. The MMI linker promotes a 3'-endo conformation for the sugar moieties at both 3'- and 5'-adjacent positions and a backbone kink involving distant residues along the 3'-direction. Comparison of R4 with other analogous hybrid duplexes previously studied in this laboratory reveals a new family of low-energy helical conformations that can be accommodated in stable duplexes and a common feature of C3'-modified sugars for adopting a C3'-endo pucker. The results of these studies emphasize the interplay of several factors that govern the formation of stable hybrid duplexes and provide a basis for the understanding of the biological role of the MMI modifications, which are important building blocks for a family of promising chimeric antisense oligonucleotides.

Base Sequence↗
PubMed1999

Timeliness and quality of care for elderly patients with acute myocardial infarction under health maintenance organization vs fee-for-service insurance.

BACKGROUND: A commonly voiced concern is that health maintenance organizations (HMOs) may withhold or delay the provision of urgent, essential care, especially for vulnerable patients like the elderly. OBJECTIVE: To compare the quality of emergency care provided in Minnesota to elderly patients with acute myocardial infarction (AMI) who are covered by HMO vs fee-for-service (FFS) insurance. METHODS: We reviewed the medical records of 2304 elderly Medicare patients who were admitted with AMI to 20 urban community hospitals in Minnesota (representing 91% of beds in areas served by HMOs) from October 1992 through July 1993 and from July 1995 through April 1996. MAIN OUTCOME MEASURES: Use of emergency transportation and treatment delay (>6 hours from symptom onset); time to electrocardiogram; use of aspirin, thrombolytics, and beta-blockers among eligible patients; and time from hospital arrival to thrombolytic administration (door-to-needle time). RESULTS: Demographic characteristics, severity of symptoms, and comorbidity characteristics were almost identical among HMO (n = 612) and FFS (n = 1692) patients. A cardiologist was involved as a consultant or the attending physician in the care of 80% of HMO patients and 82% of FFS patients (P = .12). The treatment delay, time to electrocardiogram, use of thrombolytic agents, and door-to-needle times were almost identical. However, 56% of HMO patients and 51% of FFS patients used emergency transportation (P = .02); most of this difference was observed for patients with AMIs that occurred at night (60% vs 52%; P = .02). Health maintenance organization patients were somewhat more likely than FFS patients to receive aspirin therapy (88% vs 83%; P = .03) and beta-blocker therapy (73% vs 62%; P = .04); these differences were partly explained by a significantly larger proportion of younger physicians in HMOs who were more likely to order these drug therapies. All differences were consistent across the 3 largest HMOs (1 staff-group model and 2 network model HMOs). Logistic regression analyses controlling for demographic and clinical variables produced similar results, except that the differences in the use of beta-blockers became insignificant. CONCLUSIONS: No indicators of timeliness and quality of care for elderly patients with AMIs were lower under HMO vs FFS insurance coverage in Minnesota. However, two indicators of quality care were slightly but significantly higher in the HMO setting (use of emergency transportation and aspirin therapy). Further research is needed in other states, in different populations, and for different medical conditions.

Adrenergic beta-Antagonists↗