Biomedical subjects

L Yao

Publications and source records attributed to L Yao.

At least 73 records · Page 4Linked to original sources

PubMed1999

MR imaging findings in spring ligament insufficiency.

OBJECTIVE: Spring ligament insufficiency is associated with chronic posterior tibial tendon dysfunction, and may constitute an indication for surgical repair or reconstruction. This study examines the accuracy of MRI for the diagnosis of insufficiency of the spring ligament. DESIGN AND PATIENTS: Two experienced musculoskeletal radiologists independently scored the MRI findings in 13 cases of surgically proven spring ligament insufficiency and in 18 control subjects, using a standardized scoring system. RESULTS: Insufficiency of the spring ligament was associated with increased signal heterogeneity on short TE spin echo images, and an increase in the thickness of the medial portion of the ligament. The sensitivity of MRI for the diagnosis of spring ligament insufficiency was 54-77%, while the specificity was 100%. MRI assessment of the plantar portion of the spring ligament was unreliable (kappa=0.33), but the assessment of global ligament integrity was substantially reproducible (kappa=0.76). CONCLUSION: The medial portion of the spring ligament can be reliably assessed on routine MRI. The findings of spring ligament insufficiency on MRI are only moderately sensitive but highly specific.

Case-Control Studies↗

PubMed1999

Correlations of bcl-2 and p53 expression with the clinicopathological features in tongue squamous cell carcinomas.

bcl-2 oncogene prolongs cell survival by inhibition of apoptosis. p53 tumor suppressor gene participates not only in cell proliferation control but also in induction of apoptosis. The expression of both bcl-2 and p53 proteins in 52 primary tongue squamous cell carcinomas (SCCs) was immunohistochemically explored in correlations with clinico-pathological features, patient's prognosis and apoptosis index (AI) of this tumor type. bcl-2 and p53 expression were identified in 26/52 (50%) cases and 31/52 (60%) cases, respectively. The frequency of bcl-2 expression was associated with tumor histologic grade (P = 0.0128) and marginally with mode of tumor invasion (P = 0.0671) but not with lymph nodal involvement. The frequency of p53 expression was associated with mode of tumor invasion (P = 0.0458) and pN status (P = 0.0224) but not with tumor histologic grade. Moreover, the three combined bcl-2/p53 staining patterns of bcl-2-/p53-, bcl-2+/p53- and bcl-2-/p53+, and bcl-2+/p53+ were significantly correlated with tumor histologic grade (P = 0.0299), mode of tumor invasion (P = 0.0022) and pN status (P = 0.0024). In addition, the frequent appearance of bcl-2 protein expression was associated with a decrease in AI (P = 0.0290). Our results suggest that the combined investigation on the two biological markers may have value in assessment of tumor aggressiveness, and that the suppressing mechanism of bcl-2 oncogene in regulation of apoptosis preserves in tongue SCC.

Apoptosis↗

PubMed1999

Combining qualitative with quantitative approaches to study contraceptive pill use.

According to large-scale studies, oral contraceptive users become pregnant at rates that exceed ideal use failure rates. It is thought that a major cause is missed pills, but current research on consistent contraceptive pill taking is characterized by inadequate measures and a failure to investigate women's thinking about their own patterns of use. The purpose of this study was to gain some understanding about women's interpretations of consistency in their own pill taking through combining qualitative with quantitative data. The study was conducted in China, where contraception is free and widely available. Five urban and five rural oral contraceptive users were followed for up to three pill-taking cycles during 1996 for a total of 759 person-days. Consistency of pill taking was measured with electronic data obtained from a new blister package made by Anderson Clinical Technologies (Elmhurst, IL). Data from these devices were reviewed and interpreted by the study participants during in-depth private interviews. The users' reasons for missing pills included disruptions in their daily routines, their husband's absence, spotting, and trouble implementing the family planning program's instructions to take one pill per day for 22 days and start the next cycle on the fifth day of menses. One user gave these reasons for two cycles but denied missing numerous pills in her third cycle. Data from a series of four questionnaires showed that most demographic, psychosocial, and service system characteristics were not related to missed pills. However, results suggested that the daily routines of rural living may make consistent use more likely and that instructions for taking the pill may be associated with prolonged pill-free intervals and skipping pills during episodes of spotting. Three of the 10 women were at increased risk of pregnancy during the study period because of their pill-taking pattern. We concluded that the combination of qualitative with quantitative data enhances understanding of contraceptive use. Women themselves offer plausible reasons for their use behaviors. Listening to women could be useful in improving programs.

Adolescent↗

PubMed1999

Primary musculoskeletal neoplasms: effectiveness of core-needle biopsy.

PURPOSE: To analyze the effectiveness of core-needle biopsy for evaluation of possible primary musculoskeletal neoplasms, which often are evaluated with open biopsy. MATERIALS AND METHODS: Core-needle biopsy was performed at a tertiary care institution in 141 patients suspected of having a mesenchymal neoplasm. In 85 patients, the lesion was in soft tissue; in 56 patients, the lesion was in bone. Eighty-nine patients had a malignant lesion, and 52 had a benign lesion. Twenty-eight patients had undergone previous surgery. RESULTS: In 105 (74%) patients, core-needle biopsy results were concordant with results from specimens subsequently obtained at surgery with respect to tumor histologic features and grade, or they provided sufficient diagnostic information to obviate surgery. In 36 (26%) patients, inaccurate core-needle biopsy results were obtained: In nine, results were imprecise about exact histologic features; in three, results were correct about histologic features but incorrect about tumor grade. In 25 (18%) patients, open biopsy was performed after core-needle biopsy. The accuracy and rate of performance of open biopsy for soft-tissue lesions were not significantly different from those for bone lesions. CONCLUSION: Percutaneous core-needle biopsy can be an effective alternative to open biopsy in the evaluation of possible mesenchymal neoplasms of either bone or soft tissue. Needle biopsy of such lesions, however, is best performed as part of a multidisciplinary team approach to tumor management.

Biopsy↗

PubMed1999

Alteration in aortic wall stiffness and accumulation of collagen during the prediabetic stage of type II diabetes mellitus in rats.

Aortic damage during the prediabetic stage of diabetes mellitus (DM) was investigated in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, as an animal model of type II DM. In 30 OLETF and 30 nonDM rats, an oral glucose tolerance test was performed at 10, 20 and 30 weeks of age. At 15 and 30 weeks, intravascular ultrasound images and aortic pressure were recorded and the stiffness parameter beta was calculated. The aortic walls were excised at 5, 15 and 30 weeks for histopathology and the measurement of hydroxyproline. At 10 weeks, blood glucose (mg/dl) and insulin concentrations (ng/ml) of the OLETF rats (2h; 168+/-30 and 0.82+/-0.15) were significantly high (nonDM: 118+/-15; p = 0.02 and 0.16+/-0.64; p = 0.003). At the prediabetic stage (15 weeks), beta in the OLETF rats (2.5+/-0.9) was larger than in nonDM rats (1.4+/-0.4; p = 0.0006), and the collagen (hydroxyproline) content/dry weight (mg/g) of the aortic wall was significantly higher in OLETF (33.5+/-3.1) than in nonDM rats (28.7+/-3.5; p<.05). Histopathological examination showed that from 15 weeks of age the medial wall thickness increased gradually. In the prediabetic stage, collagen accumulation may contribute to impairment of aortic wall stiffness in the OLETF rats, which would accelerate the aging process in the aortic wall.

Animals↗

PubMed1999

Cloning and expression of truncated PTHrP receptor in Escherichia coli.

To evaluate the effects of recombinant soluble parathyroid hormone related protein receptor(sPTHrPR), the RNA prepared from renal cell carcinoma was reverse-transcribed and amplified by a polymerase chain reaction(PCR). A 543 base pair fragment corresponding to extracellular domain of PTHrPR was obtained and cloned. Sequencing was performed by the dideoxy chain-termination method. Comparison of the nucleic acid sequence with the published data revealed that only one nucleotide had changed. A high level expression vector referred to as pET-3a/sPTHrPR was constructed. The binding specificity of the expression products was proved by indirect ELISA. Our preliminary experiment also showed that the expression products can block the biological activity of PTHrP.

Amino Acid Sequence↗

PubMed1999

cDNA cloning and sequencing of MH2 domain of Smad2 from human dental pulp cells.

OBJECTIVE: The purpose of this study was to clone and sequence the cDNA of MH2 domain of Smad2 from human dental pulp cells. METHODS: In this study, total RNA was isolated from primary cultured human dental pulp cells and reverse-transcribed into cDNA. The desired DNA product was obtained by nested PCR with 4 smad2 MH2 domain-specific primers. The segment was inserted into pBluescript II SK vector and the resulting plasmid was transformed into E. coli JM109. The double-strand cDNA of positive clone was sequenced by PE317-A automatic sequencing. RESULTS: cDNA of MH2 domain of Smad2 was obtained from human dental pulp cells. The sequence was consistent with that cloned from a human kidney cDNA library. No mutation was found. CONCLUSION: This study provides the first evidence of expression of smad2 in human dental pulp cells, and indicates that TGF-beta signaling may be mediated by Smad2 in human dental pulp cells. The cDNA cloned in pBluescript/S2MH2 could be used for further functional studies of Smad2 and MH2 domain in dental pulp cells.

Base Sequence↗

PubMed1999

[Relationship between expression of P16 protein and prognosis in carcinoma of nasopharynx].

We observed the relationship between p16 gene and the occurrence, development and prognosis of carcinoma of nasopharynx by means of LSAB immunohistochemistry method and investigated the expression of protein P16 in 73 cases of carcinoma of nasopharynx and 10 cases of epithelia of chronic inflammation of nasopharynx. The results showed that P16 positive rate was 100% for the epithelia of chronic inflammation of nasopharynx. It was significantly higher than the P16 positive rate for the carcinoma of nasopharynx (38.4%, P < 0.01). There was significant difference of P16 positive expression in differentiation of nasopharyngeal carcinoma (poor differentiation versus undifferentiation), clinical staging (I-II versus IV) and grading of tumor (T1-T2 versus T3, T4) (P < 0.01). There was no correlation between P16 expression and metastatic lymph node (P > 0.05). The 3-year survival rates were 88.9% and 72.9% in P16 expression (+) and (-) patients respectively (P < 0.05). These findings suggested that P16 might play an important role in the process of carcinogenesis and development of nasopharyngeal carcinoma, and P16 might be used as a valuable marker for assessment of the biological behavior and prognosis of nasopharyngeal carcinoma.

Adolescent↗

PubMed1999

[Surveillance of primary resistance in 481 cases of pulmonary tuberculosis].

OBJECTIVE: To understand the primary resistance of Mycobacterium tuberculosis in Henan province, and to make scientific prophylactic and treatment strategies. METHODS: Drug resistance surveillance (DRS) was implemented in Henan province according to WHO/IUATLD Guidelines for Surveillance of Drug Resistance in Tuberculosis(1994), and proportional method was used to detect primary resistance in 481 new cases of bacillus-positive pulmonary tuberculosis without history of anti-tuberculosis drug use. RESULTS: The primary drug resistance(PDR) rates were 22.7%, 15.8%, 22.7% and 7.7% for INH, RFP, SM and EMB, respectively. The primary multi-drug resistance (MDR) rates were 2.3%, 5.0%, 0.4% and 5.4% for HR, HRS, HRE and HRSE, respectively. CONCLUSIONS: The results show that the problem of primary resistance of Mycobacterium tuberculosis is serious in Henan province, and uniform management of anti-tuberculosis drugs and implementation of DOTs are needed.

Drug Resistance, Bacterial↗

PubMed1999

[A clinicopathologic study on eight cases of cystic and solid tumors of pancreas].

OBJECTIVE: To study the clinicopathologic characteristics, differentiation patterns and histogenesis of cystic and solid tumors of the pancreas (CSTP). METHODS: 8 cases of CSTP were studied using histologic (HE and PAS), immunohistochemical (S-P method) and electron microscopic techniques. RESULTS: All the patients were adolescent and young adult females, 14-33 years in age (mean 25.3 years) without recurrence after tumor resection. The mean diameter of tumors was 9.6 cm, all encapsulated. Histological examination showed presence of solid sheets, pseudopapillary, in all of the cases. Hemorrhage, foam cells, and cholesterol crystals were often found. Immunohistochemically, 8 cases were positive for alpha(1)-AT and lysozyme; 6 cases expressed vimentin, 2 cases expressed actin, and CgA-positive cells found in the tumor cell nests in one case. All of the cases showed PR, and 4 cases showed ER positive immunoreactivity in the majority of tumor cells, but negative for CK AE1, CK AE3, EMA, Synaptophysin, ACTH, gastrin, somatostatin, insulin, and glucogan in all the cases. Electron microscopy of 3 cases showed evidences of polymorphism in differentiation of the tumor cells, including the transitional appearance into ducts, acinus, and endocrine cells. Weibel-Palade body found in tumor cells in one out of 8 cases. CONCLUSIONS: (1) CSTP is a distinct clinicopathologic entity in young female patients with a benign clinical course. (2) CSTP develops from primitive pancreatic cells, with the potentiality of developing into ducts, acinus, and endocrine cells.

Actins↗

PubMed1999

[The substituent structures and characteristic infrared spectra of alpha-furan esters].

The characteristic infrared bands of the alpha-furoic esters, alpha-furancarbinol esters and alpha-furanacrylic esters were assigned, and the changing rules of the IR absorption frequency of the alpha-furan esters with alpha-substituent structure were discussed. The results indicated there are three characteristic bands in alpha-furan ring. The strong absorption at 1641 cm(-1) is assigned to the C=C double bond stretching mode in the alpha-furanacrylic esters, while the absorption at 973 cm(-1) is the out-of-plane =C-H bending mode for a trans di-substituted alkene, the strong absorption at about 1713 cm(-1) is assigned to a C=O stretch, and the three strong absorptions near 1305, 1260 and 1165 cm(-1) are due to the symmetric and assymmetric stretching vibrations of C-O-C bond in the ester groups.

Esters↗

PubMed1998

Vasostatin, a calreticulin fragment, inhibits angiogenesis and suppresses tumor growth.

An endothelial cell inhibitor was purified from supernatant of an Epstein-Barr virus-immortalized cell line and identified as fragments of calreticulin. The purified recombinant NH2-terminal domain of calreticulin (amino acids 1-180) inhibited the proliferation of endothelial cells, but not cells of other lineages, and suppressed angiogenesis in vivo. We have named this NH2-terminal domain of calreticulin vasostatin. When inoculated into athymic mice, vasostatin significantly reduced growth of human Burkitt lymphoma and human colon carcinoma. Compared with other inhibitors of angiogenesis, vasostatin is a small, soluble, and stable molecule that is easy to produce and deliver. As an angiogenesis inhibitor that specifically targets proliferating endothelial cells, vasostatin has a unique potential for cancer treatment.

Animals↗

PubMed1998

Small structural ensembles for a 17-nucleotide mimic of the tRNA T psi C-loop via fitting dipolar relaxation rates with the quadratic programming algorithm.

Solution structures are typically average structures determined with the help of nmr-derived distance and torsion angle information. However, when a biomolecule populates significantly different conformations, the average structure might be prone to artifacts, and other refinement strategies are necessary. For example, when experimental restraints are used in molecular dynamics simulations in a time-averaged fashion (MDtar), the experimental structural information does no longer need to be satisfied at each step of the simulation; instead, the whole trajectory must agree with the restraints. However, the resulting structural ensembles are large and not unique and it is not trivial to extract the essential dynamic features for a system. Here we demonstrate that large MDtar ensembles can be simplified substantially by reducing the number of members to just a few on the basis of adjusting the individual probabilities of the members with the PDQPRO program [N. B. Ulyanov et al. Biophysical Journal (1995), Vol. 68, p. 13]. This algorithm finds the global minimum for a search function that represents the best match of a given ensemble with the experimental dipolar interproton relaxation rates. We have applied this strategy to a 17-residue RNA hairpin, whose loop exhibited considerable flexibility evident from nmr data. This 17mer is a mimic of the T psi C-loop of tRNA, where nucleotide 54 is usually a ribosylthymidine. The methylation of U54, which is completely buried in transfer ribonucleic acid, is administered by tRNA (m5 U54)-methyltransferase (RUMT). Since the 17mer is a good substrate for RUMT, we previously concluded that the flexibility of the 17mer's loop is a key to how RUMT gains access to the methylation site [L. J. Yao et al. Journal of Biomolecular NMR (1996) Vol. 9. p. 229]. Application of the PDQPRO algorithm to the previously acquired MDtar trajectories allowed us to reduce the number of conformations from several hundred to one major and five or six minor conformations with individual populations from approximately 5% to approximately 50% without any deterioration in the match with the experimental data. The major conformation exhibits a continuation of A-form helicity through part of the loop, involving C60 and U59. In this and most other conformations the methylation site in U54 is no longer buried.

Algorithms↗

PubMed1998

OFQ reverses the kappa-opioid receptor-mediated depression of calcium current in rat dorsal root ganglion neurons.

Since the characterization of orphanin FQ (OFQ), the endogenous ligand of ORL1 receptor, much work has focused on its physiological functions. OFQ was reported to antagonize the effect of opioid-induced antinociception, although its mechanism remains obscure. In the present study, whole-cell patch clamp recording technique was used to observe if OFQ can reverse the inhibition of calcium current produced by the kappa-opioid agonist U50,488H (U50) in acutely dissociated rat DRG neurons. The concentrations of OFQ and U50 were 50 nM and 10 microM, respectively. Among 49 cells recorded, the calcium channel currents of 37 (75.5%) cells were inhibited by U50, of which 30 (81.1%) cells could be reversed by OFQ. It was interesting to note the similarity between OFQ and the well characterized anti-opioid peptide CCK-8 in that it reversed kappa-opioid receptor agonist induced suppression on calcium channel current, while by itself showed a calcium channel suppressive effect. Thus OFQ may be regarded as another anti-opioid peptide.

Animals↗

PubMed1998

Involvement of Bruton's tyrosine kinase in FcepsilonRI-dependent mast cell degranulation and cytokine production.

We investigated the role of Bruton's tyrosine kinase (Btk) in FcepsilonRI-dependent activation of mouse mast cells, using xid and btk null mutant mice. Unlike B cell development, mast cell development is apparently normal in these btk mutant mice. However, mast cells derived from these mice exhibited significant abnormalities in FcepsilonRI-dependent function. xid mice primed with anti-dinitrophenyl monoclonal IgE antibody exhibited mildly diminished early-phase and severely blunted late-phase anaphylactic reactions in response to antigen challenge in vivo. Consistent with this finding, cultured mast cells derived from the bone marrow cells of xid or btk null mice exhibited mild impairments in degranulation, and more profound defects in the production of several cytokines, upon FcepsilonRI cross-linking. Moreover, the transcriptional activities of these cytokine genes were severely reduced in FcepsilonRI-stimulated btk mutant mast cells. The specificity of these effects of btk mutations was confirmed by the improvement in the ability of btk mutant mast cells to degranulate and to secrete cytokines after the retroviral transfer of wild-type btk cDNA, but not of vector or kinase-dead btk cDNA. Retroviral transfer of Emt (= Itk/Tsk), Btk's closest relative, also partially improved the ability of btk mutant mast cells to secrete mediators. Taken together, these results demonstrate an important role for Btk in the full expression of FcepsilonRI signal transduction in mast cells.

Agammaglobulinaemia Tyrosine Kinase↗

PubMed1998

Tumor necrosis factor-alpha- or lipopolysaccharide-induced expression of the murine P-selectin gene in endothelial cells involves novel kappaB sites and a variant activating transcription factor/cAMP response element.

Tumor necrosis factor-alpha (TNF-alpha) or lipopolysaccharide (LPS) increases expression of the P-selectin gene in murine, but not in human, endothelial cells. These mediators augment expression of a reporter gene driven by the murine, but not the human, P-selectin promoter in transfected endothelial cells. The regions from -593 to -474 and from -229 to -13 in the murine P-selectin promoter are required for TNF-alpha or LPS to stimulate reporter gene expression. Within these regions, we identified two tandem kappaB elements, a reverse-oriented kappaB site and a variant activating transcription factor/cAMP response element (ATF/CRE), that participate in TNF-alpha- or LPS-induced expression. The tandem kappaB elements bound to NF-kappaB heterodimers and p65 homodimers, the reverse-oriented kappaB site bound to p65 homodimers, and the variant ATF/CRE bound to nuclear proteins that included activating transcription factor-2. Mutations in each individual element eliminated binding to nuclear proteins and decreased by 20-60% the TNF-alpha- or LPS-induced expression of a reporter gene driven by the murine P-selectin promoter in transfected endothelial cells. Simultaneous mutations of all elements further decreased, but did not abolish, induced expression. Co-overexpression of p50 and p65 enhanced murine P-selectin promoter activity in a kappaB site-dependent manner. These data indicate that the kappaB sites and the variant ATF/CRE are required for TNF-alpha or LPS to optimally induce expression of the murine P-selectin gene. The presence of these elements in the murine, but not the human, P-selectin gene may explain in part why TNF-alpha or LPS stimulates transcription of P-selectin in a species-specific manner.

Animals↗

PubMed1998

Use of high-precision gas isotope ratio mass spectrometry to determine natural abundance 13C in lutein isolated from C3 and C4 plant sources.

A method was developed for high-precision stable carbon isotope ratio analysis of lutein isolated from a C3 (marigold flower) and a C4 (corn gluten meal) plant source using gas chromatography-combustion interfaced isotope ratio mass spectrometry. The natural abundance of 13C (expressed as delta 13C versus the international standard, Pee Dee Belemnite, in per mil units, denoted /1000) in lutein isolated from marigold flower and corn gluten meal was determined to be -29.90 +/- 0.20/1000 and -19.77 +/- 0.27/1000 (mean +/- S.D.), respectively. The high precision of gas isotope ratio mass spectrometry is potentially applicable to detect differences of isotopic composition of lutein in the blood, tissues, or excreta of animal models or humans that result from differences in the natural abundance of 13C in C3 and C4 plant foods.

Carbon Isotopes↗

PubMed1998

A proteasome inhibitor, an antioxidant, or a salicylate, but not a glucocorticoid, blocks constitutive and cytokine-inducible expression of P-selectin in human endothelial cells.

Proteasome inhibitors, antioxidants, salicylates, or glucocorticoids block the cytokine-induced expression of the endothelial cell adhesion molecules E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1. These pharmacological agents have been assumed to inhibit the expression of adhesion molecules primarily by blocking activation of the transcription factor NF-kappaB. We found that the proteasome inhibitor ALLN, the antioxidant PDTC, or sodium salicylate, but not the glucocorticoid dexamethasone, inhibited both the constitutive and the interleukin-4- or oncostatin M-induced expression of the adhesion molecule P-selectin in human endothelial cells. ALLN, PDTC, or sodium salicylate decreased P-selectin expression without a detectable requirement for inhibition of NF-kappaB activation or for an intact kappaB element in the P-selectin gene. These results extend the potential anti-inflammatory utility of such drugs to inhibition of P-selectin expression and suggest that they have important actions that do not involve the NF-kappaB system.

Animals↗