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Biomedical subjects

K Sun

Publications and source records attributed to K Sun.

At least 73 records · Page 4Linked to original sources
PubMed2000

[The digestive functions of the stomach after esophagectomy with vagus nerve preserved or severed in esophageal cancer patients: a comparative study].

OBJECTIVE: To study the feasibility, indication, and clinical significance of preserving the vagus nerve during esophagectomy for patients with cancer of the esophagus. METHODS: The digestive functions of the stomach were studied and compared before and after esophagectomy in patients with vagus nerve intact (n = 11) or severed (n = 12). RESULTS: According to Angorn's grading system, patients with vagus nerve preserved (VNP) had less symptoms after operation than those with vagus nerve severed (VNS). The gastric emptying time of the intrathoracic stomach in patients with VNS was much prolonged compared with that in patients with VNP. There was no significant difference in the preoperative and postoperative mean basal gastric acid output and the 24-hour pH monitoring in patients with VNP, while in VNS patients they were significantly decreased after operation. Fasting serum gastrin level in VNS patients was significantly elevated but this was not observed in VNP patients. Fibroptic endoscopic examination revealed higher incidence of postoperative atrophic gastritis in VNS than in VNP patients. CONCLUSION: Preservation of the vagal trunks during surgical resection for cancer of the esophagus is beneficial to keep the postoperative digestive functions of the stomach in a better condition.

Esophageal Neoplasms↗
PubMed2000

[Clinical pathological analysis of clear cell odontogenic carcinoma].

OBJECTIVE: To investigate clinical pathological characteristics and biologic behavior of clear cell odontogenic carcinoma. METHODS: Analysis of clinical data, microscopic and electromicroscopic observation of 8 cases of clear cell odontogenic carcinoma. RESULTS: The tumor occurred mainly in female and involved right mandible. 37.5% had regional lymph node metastases at the time of operation. Recurrence rate was 33.3%. The tumor had no capsule and consisted of clear cell and basaloid cells which arranged in nests and strands. Tumor cells often grew close to the blood vessels and caused bone resorption. There were less cell organelle and swelling of mitochondria. CONCLUSION: This tumor belongs to middle grade malignant tumor and should be called clear cell odontogenic carcinoma.

Adenocarcinoma, Clear Cell↗
PubMed2000

[Factors influencing survival rate in adenoid cystic carcinoma of the salivary glands].

OBJECTIVE: To study factors influencing survival rate of adenoid cystic carcinoma (ACC) of the salivary glands. METHODS: One hundred and twelve cases were followed up for move than ten years and were studied to investigate factors influencing the survival rate of patients. Statistical analysis was performed using a computer program (Survcalc, John Wiley Co.). The data were statistically treated for survival curves according to the kaplan-meier method. The log rank tests were employed to assess the statistical significance of various groups. RESULTS: The age of the patients younger than 50 years old, early clinical stage, glandular/tubular histological type and tumor without nerve involvement had the best prognosis. Age of the patients older than 50 years old, ACC in the submandibular gland, advanced clinical stage (stage III and IV), solid histological type and tumor with nerve involvement had a poor prognosis. CONCLUSIONS: Age of the patients, tumour site, clinical stage, histological type and with or without nerve involvement are the important factors influencing the prognosis.

Adolescent↗
PubMed2000

[Immobilization osteoporosis and fracture in children].

This study was intended to enhance the diagnostic vigilance of immobilization osteoporosis with fracture and explore its prevention and treatment. Thirteen children with the hip disease underwent one to nine months of plaster cast after operation. A retrospective analysis was made on these 13 patients with fracture and immobilization osteoporosis. The result showed that disuse fracture occurred in fifteen places of their femora. All of these cases were cured by non-operative and drug treatment. These data suggest that for the cases of immobilization osteoporosis it is important to prevent fracture by means of early diagnosis, proper drugs, early function exercise, appropriately shorter period of fixation and the avoidance of trauma.

Child↗
PubMed2000

[The degradation performance of bioabsorbable acylchitin fiber reinforced PLA composite materials in vitro and in vivo].

The present authors have investigated the degradation performance of acylchitin fiber reinforced polylactide composite materials plates both in vitro and in vivo. The initial flexural strength and the initial flexural modulus of this plate are 114.72 MPa and 3980.05 MPa, respectively. The flexural strength of this plate decreases to 31.42 MPa after the plate has been submerged in injectio natrii lactatic ringeri tissue fluid for a period of 16 weeks at 37 degrees C. Both the in vitro degradation performance and the strength retention of this plate are better than those of the self-reinforced PGA/PLA and PGA, though the initial strength of the latter two being much higher than that of the former. The degradation products of the chitin/PLA composite materials can be absorbed by metabolic pathway.

Animals↗
PubMed2000

[The study of p16 gene mutation and methylation in laryngeal squamous cell carcinoma].

OBJECTIVE: To investigate the development and mechanism of the p16 gene inactivation in laryngeal squamous cell carcinoma (LSCC). METHODS: With PCR-based methylation assay and PCR-SSCP, first and second exon mutation in p16 gene and methylation of endogenase in promoter in 32 cases of LSCC and paracancer tissue were studied. RESULTS: No mutation were found in first and second exon in the samples; methylation of Cfo I were detected in 6 cases in first exon, methylation of Sac II was found in 4 cases, and methylation of Hpa II in 4 cases. In second exon, methylation of Hpa II was detected in 5 cases and methylation of Cfo I in 6 cases. CONCLUSION: Methylation of promoter in p16 gene is one of the important mechanisms of the inactivation of the gene. The inactivation of p16 gene has a close relation with the development and progress of LSCC.

Carcinoma, Squamous Cell↗
PubMed1999

[Loss of heterozygosity and microsatellite instability in laryngeal carcinoma near p16 gene]

OBJECTIVE: To search for the minimal overlap region of tumor suppressor gene in laryngeal carcinoma and discuss the correlation of p16 gene with laryngeal carcinogenesis. METHODS: Five microsatellite polymorphism markers near p16 gene were selected to detect loss of heterozygosity (LOH) and microsatellite instability (MI) in 60 cases of laryngeal squamous cell carcinoma. RESULTS: The frequencies of LOH in 5 markers were less than 23.1%, while the frequencies of MI in 2 markers were higher, with the highest frequency (46.1%) in D9S1752. CONCLUSION: The results suggest that the deletion of p16 gene does not play an important role in the laryngeal carcinogenesis and there may exist a gene around D9S1752 participating in the development of laryngeal carcinoma, which correlates with the mutation of repair gene.

Journal Article↗
PubMed1999

Structural organization and expression of the mouse gene for Pur-1, a highly conserved homolog of the human MAZ gene.

We have characterized the genomic structure and expression of the mouse gene for Pur-1. The cloned Pur-1 gene spans a 5-kb region encompassing the promoter, five exons, four introns and the 3'-untranslated region. All exon-intron junction sequences conform to the GT/AG rule. The promoter region has typical features of a housekeeping gene: a high G + C content (77.5%); a high frequency of CpG dinucleotides, in particular within the region 0.5 kb upstream of the site of initiation of translation; and the absence of canonical TATA and CAAT boxes. S1 nuclease protection assay demonstrated the presence of multiple sites for initiation of transcription around a site 108 nucleotides upstream of the ATG codon. Comparison of Pur-1 with the human gene for MAZ (Myc-associated zinc finger protein) revealed a striking homology of both their nucleotide and deduced protein sequences, an identical genomic organization and high similarity in promoter architecture and mRNA expression pattern. Sequence analysis of the 5'-flanking region of Pur-1 revealed numerous potential binding sites for transcription factors Sp1, AP-2 and Pur-1/MAZ itself. An element required for basal Pur-1 expression was mapped from nucleotide -258 to +43. This region also mediated stimulation of basal transcription by ectopically expressed MAZ protein. We conclude that the Pur-1 gene is the murine homolog of human MAZ and, like it, belongs to the family of housekeeping genes.

Animals↗
PubMed1999

Interconversion of cortisol and cortisone by 11beta-hydroxysteroid dehydrogenases type 1 and 2 in the perfused human placenta.

The human placenta contains two types of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). The exclusive oxidase 11beta-HSD2 has been suggested to protect the fetus from high levels of maternal glucocorticoids by converting cortisol to inactive cortisone. Perfused term human placenta was used to examine the activity of the oxoreductase 11beta-HSD1 and to determine the regulation of cortisol effects on placental vascular tone and corticotropin-releasing hormone (CRH) output by 11beta-HSD. Radioimmunoassay showed that there was substantial cortisol (295+/-57 nM) detected in the fetal vein upon perfusion of cortisol (2 microM; perfusion rate, 12 ml/min) into the maternal intervillous space. Output of cortisol increased to 559+/-22 nM on the fetal side (P<0.05) with concurrent perfusion of carbenoxolone (CBX; 1 microM), a non-specific 11beta-HSD inhibitor. Cortisol formation increased in a dose-dependent manner with infusion of cortisone (0.1-2 microM) into the maternal intervillous space reaching 15 and 23 nM in fetal and maternal venous outflows respectively at 2 microM cortisone perfusion. There was no significant effect of cortisol either alone or in combination with CBX on the fetal arterial perfusion pressure, but cortisol perfusion increased CRH output into the fetal vein. It is concluded that activities of both 11beta-HSD1 and -2 are demonstrable in perfused human placenta in vitro, and these enzymes affect transplacental glucocorticoid transfer. These activities may provide a precise mechanism to control the passage of maternal glucocorticoids to the fetal circulation, and to regulate glucocorticoid effects within the placenta.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1999

Descending necrotizing mediastinitis: mediastinal drainage with or without thoracotomy.

Descending necrotizing mediastinitis (DNM) is a lethal process originating from odontogenic, pharyngeal, or cervical infections that descends along the fascial planes into the mediastinum. The surgical management ranges from cervical drainage to routine thoracotomy but remains controversial. We here describe two patients treated successfully who underwent cervical drainage alone or cervical drainage combined with thoracotomy. Wide cervical exploration with postural drainage was effective in one patient with limited DNM above the carina. Mediastinal exploration through thoracotomy was required to salvage the other with DNM extending below the carina and associated with pericardial invasion.

Adult↗
PubMed1999

Local modulation by 11beta-hydroxysteroid dehydrogenase of glucocorticoid effects on the activity of 15-hydroxyprostaglandin dehydrogenase in human chorion and placental trophoblast cells.

NAD+-dependent 15-hydroxy-PG dehydrogenase (PGDH) is the major enzyme involved in the initial inactivation of PGs, and its activity is reduced by glucocorticoids, cortisol (F), and dexamethasone (DEX). In turn, glucocorticoid regulation of PGDH activity in placenta and chorion could be regulated indirectly by 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity. In the placenta, 11beta-HSD2 is the dominant isoform, acting as a dehydrogenase [F to cortisone (E)]; and in chorion, 11beta-HSD1 predominates as a reductase (E to F). The present study was designed to determine whether glucocorticoid regulation of PGDH activity in placenta and chorion could be regulated indirectly by 11beta-HSD activity. We obtained Percoll-purified human placental and chorion trophoblast cells from uncomplicated term pregnancies, cultured them for 72 h, then treated the cells with cortisol (100 nmol/L), cortisone (1 micromol/L), or DEX (100 nmol/L), in the presence or absence of carbenoxolone (CBX, 800 nmol/L), an 11beta-HSD inhibitor, for 24 h. Activity of PGDH was assessed by incubation (4 h) with PGF2alpha (282 nmol/L) and measurement of conversion to 13,14-dihydro-15-keto PGF2alpha. CBX alone had no effect on PGDH activity in either placenta or chorion trophoblast cells. In chorion, E significantly inhibited PGDH activity, and this effect was reversed by addition of CBX. F and DEX significantly inhibited PGDH, and this effect was unaltered by coadministration of CBX. In contrast, in placenta, there was no effect of E, or of E with CBX, on PGDH activity. However, F and DEX inhibited PGDH, and the effect of F (but not DEX) was greater in the presence of CBX. In conclusion, we suggest that effects of E and F on PGDH are modified by the tissue-specific expression of 11beta-HSD isoforms.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1999

Isolation of cDNAs encoding gibbon and monkey platelet and T cell activation antigen 1 (PTA1).

Human platelet and T cell activation antigen 1 (PTA1) is a 67kDa type I transmembrane glycoprotein mainly expressed on the surface of activated T cells and platelets, and is involved in the development of human cytotoxic T cell (CTL) as well as platelet activation and aggregation. We have cloned and sequenced gibbon PTA1 (gPTA1) and monkey PTA1 (mPTA1) cDNAs by RT-PCR from gibbon leukemic cell line MLA 144 and PHA-induced Rhesus monkey PBMC respectively. The mature proteins of gPTA1, mPTA1 and human PTA1 (hPTA1) share 93-95% amino acid similarity with the highest similarity in domain 1 of extracellular region. All the important features of PTA1 molecule are conserved among these Primates: (1) the ORF encoding 336 amino acid residues including signal sequence (18aa), extracellular region (232aa), transmembrane sequence (25aa) and cytoplasmic region (61aa); (2) two conserved pairs of Cys (Cys19 to Cys90 and Cys134 to Cys204) forming disulfide bonds stabilizing the two immunoglobulin superfamily V-like domains; (3) eight putative N-linked glycosylation sites (except gPTA1 with nine sites) and three O-linked glycosylation sites in extracellular region; and (4) predicated protein kinase C phosphorylation sites (Thr275 and Ser311), casein kinase II sites (Ser295 and The299) and the potential tyrosine phosphorylation site (Tyr304). These data indicate that PTA1 molecule is highly conserved among the Primates and may play important roles in immune response.

Amino Acid Sequence↗
PubMed1999

[Loss of heterozygosity and microsatellite instability in laryngeal carcinoma near p16 gene].

OBJECTIVE: To search for the minimal overlap region of tumor suppressor gene in laryngeal carcinoma and discuss the correlation of p16 gene with laryngeal carcinogenesis. METHODS: Five microsatellite polymorphism markers near p16 gene were selected to detect loss of heterozygosity (LOH) and microsatellite instability (MI) in 60 cases of laryngeal squamous cell carcinoma. RESULTS: The frequencies of LOH in 5 markers were less than 23.1%, while the frequencies of MI in 2 markers were higher, with the highest frequency (46.1%) in D9S1752. CONCLUSION: The results suggest that the deletion of p16 gene does not play an important role in the laryngeal carcinogenesis and there may exist a gene around D9S1752 participating in the development of laryngeal carcinoma, which correlates with the mutation of repair gene.

Gene Deletion↗
PubMed1999

Improved fusion partners transfected with DNA fragment encoding IL-11 on generation of human B lymphocyte hybridomas.

IL-11, a less identified cytokine, possesses some overlapping functions with IL-6 that are able to facilitate the growth and antibody secretion of B lymphocyte hybridomas. In this report, a DNA fragment encoding human IL-11 was transduced into fusion partners (mouse myelomas Ag8.653 and SP2/0, and human lymphoblastoid cell line HF2) mediated by lipofection. The transfected cells selected with G418 secreted IL-11 constitutively over the range of 32.4 +/- 10.5 units/ml to 76.6 +/- 18.4 units/ml, which could be inhibited by an IL-11 neutralizing MAb up to 80%. The fusion frequency of PBMC doubled, while that of LCLs displayed a 2.4- or 3.3-fold increase, when fused with the transfected fusion partners, respectively. The derived hybridomas from IL-11 secreting fusion partner secreted 3 or 4 times as many immunoglobulins as that from its ancestor. Our data indicate that IL-11 gene transfected fusion partners are improved cell lines for generation of human B lymphocyte hybridomas, and IL-11 may contribute to the increased fusion frequency and antibody secretion of B lymphocyte hybridomas.

Animals↗
PubMed1999

[Susceptibility gene location of simple congenital heart defect by transmission disequilibrium test].

OBJECTIVE: To locate the susceptibility gene of human simple congenital heart defect(CHD) and provide a sound basis for further gene cloning. METHODS: Three short tandem repeats(STRs) in regions of chromosome 7p14-15, 17q21 where exist Hox gene family's A, B clusters which regulate the embryonic heart development were chosen. Genotypes of 112 members in 39 CHD families were analyzed by amplifying the STR fragments using fluorescence-PCR technique. Then transmission disequilibrium test(TDT) was used to test the data of genotypes. RESULTS: Statistical chi(2) values of D7S1808, D7S673 and D17S791 were 31.3(P<0.005), 11.12(P<0.05) and 6.65 (P>0.05) respectively. These suggest that the former two are associated with CHD, while the latter is not. CONCLUSION: Human simple CHD is associated with Hox gene A cluster. Hox A gene may be a candidate CHD's susceptive genes. The location of the CHD's susceptive genes is in chromosome 7p14-15.

Chromosomes, Human, Pair 7↗
PubMed1999

[Rapid detection of trisomy 21 by quantitative polymerase chain reaction].

OBJECTIVE: Studying gene diagnosis of trisomy 21 by means of quantitative polymerase chain reaction(PCR). METHODS: Polymorphic short tandem repeat(STR) at D21S11 served as the gene marker, and a pair of primers was synthesized. The samples from 11 normal subjects and 28 cases of trisomy 21 were analyzed by quantitative PCR. RESULTS: 10 normal subjects showed two bands with a ratio of 1:1, and a subject showed one band. Of 28 cases of trisomy 21, 24 cases showed two bands with a ratio of 2:1, 3 cases showed three bands with a ratio of 1:1:1, and 1 case showed one band. CONCLUSION: Polymorphic STR at D21S11 is a valuable gene marker for diagnosis of trisomy 21. Trisomy 21 can be diagnosed rapidly and accurately within 24 hours by quantitative PCR.

Down Syndrome↗