Biomedical subjects
Publications and source records attributed to X Dai.
Using pulsed perturbation-facilitated optical-optical double resonance (PFOODR) spectroscopy, the 2(3)Delta(g) state of (7)Li(2) (electronic configuration (varsigma(g)2s) (4ddelta(g)), effective principal quantum number n* = 4.101) has been observed and assigned. Molecular constants and a RKR potential energy curve were obtained. The major molecular constants are Copyright 2000 Academic Press.
We reviewed 27 cementless primary total hip replacements in patients with osteoarthrosis secondary to congenital dysplasia of the hip. Autogenous bone grafting was used as augmentation. On average the follow-up period was 9 years. Two hips were revised and three acetabular components were considered loose. In hips with loose cups the average graft coverage was significantly greater than in stable hips. The use of a cementless acetabular component is encouraging for reconstruction, although extensive grafting should be avoided. Our study suggests that cementless reconstruction in dysplastic hips yields a satisfactory outcome.
The effects of pH, ionic strength and FA (fulvic acid) on the sorption and desorption of Eu(III) and Yb(III) on alumina were respectively investigated by using batch technique and radiotracers 152 + 154Eu and 169Yb. The distribution coefficients for sorption and desorption of Eu on alumina at pH 4.4, 4.6 and 5.7 in 1 mol/l NaCl solutions as a function of solid phase concentration were determined in the presence or absence of FA. The effects of pH, FA and ionic strength on the distribution coefficients for sorption and desorption of Yb on alumina were determined in 0.01-2.0 mol/l NaNO3. It was found that pH and FA influenced the sorption of Eu(III) and Yb(III) on alumina greatly. A surface hydrolysis model can satisfactorily and qualitatively explain the observations on bare alumina. The competition among the complexations of surface free hydroxyl groups, soluble and sorbed fulvic acids can satisfactorily and qualitatively explain the observations on the coated alumina.
Gingival overgrowth commonly occurs coincident to therapy with calcium channel blockers. The biologic mechanism for this condition is unknown; however, many clinicians suggest that poor oral hygiene may contribute to development of the overgrowth. This study tests the hypothesis that collagenous protein synthesis by gingival fibroblasts is synergistically enhanced when they are exposed to both nifedipine (N) and the pro-inflammatory cytokine, interleukin-1-beta, a cytokine expressed in inflamed gingiva. Human gingival fibroblasts were isolated from biopsies of normal gingiva and cells separated into two groups. Group 1 was exposed to media containing 0, 5, 50, or 500 pg/ml IL-1-beta, or 10(-7) M N for 7 days; Group 2 was exposed to those concentrations of IL-1-beta +10(-7) M N. [3H]-proline was added to the medium for the final 24 h. Cells and matrix were harvested and radioactivity determined by liquid scintillation analysis. Means (d.p.m./10(3) cells) were compared by factorial ANOVA and Scheffé comparisons. Collagenous protein synthesis was significantly reduced by 5 pg/ml IL-1-beta +10(-7) M N and enhanced by 500 pg/ml IL-1-beta +10(-7) M N as compared to N or IL-1-beta alone. Thus, patients may be more susceptible to gingival overgrowth coincident to nifedipine therapy as a result of the synergistic enhancement of connective tissue synthesis by these agents.
Serial radiographic measurements of polyethylene wear were performed in 38 hips (33 patients) with primary cementless total hip arthroplasty (THA). The average follow-up period was 131.8 months. All prostheses were assessed as radiographically stable at the latest follow-up. A two-dimensional method was used to calculate the relative migration of the femoral head center to the cup center. The average total linear wear and wear rate were 1.22 mm and 0.11 mm/year, respectively. The degree of wear in the first 2 postoperative years accounted for nearly 40% of the total wear at the end of the study (average follow up: 131.8 +/- 10.0 months, +/-SD). The migration of the femoral head at an average period of 3. 4 months after operation accounted for 56% of the amount of wear in the first 2 years. Wear rate decreased gradually with time and stabilized after the fourth year. However, in 2 patients, a progressive increase in the wear rate was associated with severe osteolysis and failure of THA. Both creep and wear contributed to the femoral penetration into the polyethylene liner. The influence of creep cannot be ruled out, especially in the early period after operation. Polyethylene wear is a multifactorial process, and the study of individual wear patterns might be useful in identifying patients who are at risk of late failure of THA.
The application of the Mobius inversion formula to the specific-heat-phonon spectrum inversion problem (SPI) initially appeared promising [N.X. Chen, Phys. Rev. Lett. 64, 1193 (1990); J. Maddox, Nature (London) 344, 377 (1990)]. However, no one has previously been able to obtain the exact Debye spectrum with the correct cut-off factor and frequency dependence from the Mobius formula. The main difficulty arises from the fact that the Mobius function &mgr;(n) is not completely known for large n in practice. In this paper, some exact solutions of SPI are obtained by using the Mobius inversion formula, most importantly the Debye spectrum as a special case, and the problem of the unknown Mobius function &mgr;(n) for large n is avoided. It is shown that the Mobius inversion formula can be useful for exact solutions to spectral inversion problems.
DNA sequencing upstream of the Salmonella enterica serovar Typhi pilV and rci genes previously identified in the ca. 118-kb major pathogenicity island (X.-L. Zhang, C. Morris, and J. Hackett, Gene 202:139-146, 1997) identified a further 10 pil genes apparently forming a pil operon. The product of the pilS gene, prePilS protein (a putative type IVB structural prepilin) was purified, and an anti-prePilS antiserum was raised in mice. Mutants of serovar Typhi either lacking the whole pil operon or with an insertion mutation in the pilS gene were constructed, as was a strain in which the pilN to pilV genes were driven by the tac promoter. The pil(+) strains synthesized type IVB pili, as judged by (i) visualization in the electron microscope of thin pili in culture supernatants of one such strain and (ii) the presence of PilS protein (smaller than the prePilS protein by removal of the leader peptide) on immunoblotting of material pelleted by high-speed centrifugation of either the culture supernatant or sonicates of pil(+) strains. Control pil mutants did not express the PilS protein. A pilS mutant of serovar Typhi entered human intestinal INT407 cells in culture to levels only 5 to 25% of those of the wild-type strain, and serovar Typhi entry was strongly inhibited by soluble prePilS protein (50% inhibition of entry at 1.4 microM prePilS).
We examined the reliability, cross-instrument validity, and factor structure of Chinese adaptations of the Personality Diagnostic Questionnaire (PDQ-4+; N = 1,926) and Personality Disorders Interview (PDI-IV; N = 525) in psychiatric patients. Comparisons with data from Western countries suggest that the psychometric properties of these two instruments are comparable across cultures. Low to modest agreement between the PDQ-4+ and PDI-IV was observed for both dimensional and categorical personality disorder evaluations. When the PDI-IV was used as the diagnostic standard, the PDQ-4+ showed higher sensitivity than specificity, and higher negative predictive power than positive predictive power. Factor analyses of both instruments replicated the four-factor structure O'Connor and Dyce (1998) found in Western samples. Results suggested that conceptions and measures of DSM-IV personality disorders are cross-culturally generalizable to Chinese psychiatric populations.
The protein c-erbB-2, also known as Her2/neu, is a prognostic breast cancer marker assayed in tissue biopsies from women diagnosed with malignant tumors. Present studies suggest that soluble fragments of the c-erbB-2 oncogene may be released from the cell surface and become detectable in patients with carcinoma of the breast. Consequently, the purpose of this study was to assay the c-erbB-2 protein in the saliva and serum of women with and without carcinoma of the breast and to determine whether the protein possesses any diagnostic value. To determine the diagnostic utility of this oncogene, the soluble form of the c-erbB-2 protein was assayed in the saliva and serum using ELISA in three different groups of women. The three groups consisted of 57 healthy women, 41 women with benign breast lesions, and 30 women diagnosed with breast cancer. To compare the relative diagnostic utility of the c-erbB-2 protein, CA 15-3 was also measured. The CA 15-3 measurements served as a "gold standard" by which to compare the c-erbB-2 protein's diagnostic effectiveness. We found c-erbB-2 protein in the saliva and serum of all three groups of women. The salivary and serological levels of c-erbB-2 in the cancer patients, however, were significantly higher (P < 0.001) than the salivary and serum levels of healthy controls and benign tumor patients. Additionally, the c-erbB-2 protein was found to be equal to or to surpass the ability of CA 15-3 to detect patients with carcinoma. The results of the pilot study suggest that the c-erbB-2 protein may have potential use in the initial detection and/or follow-up screening for the recurrence of breast cancer in women.
OBJECTIVE: To study the joint neurotoxic effects of phoxim (Pho) and fenvalerate (Fen) on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na(+) currents in dorsal root ganglion (DRG) neurons of adult rat. METHODS: Whole cell patch clamp technique was used to test the effects of Pho and Fen on TTX-S and TTX-R sodium currents in DRG neurons. RESULTS: The inactivation of TTX-R sodium channel was obviously slowed down by Fen. The tau(Na) of peak currents at doses of 10, 50 and 100 micromol/L Fen and control groups were (8.10 +/- 2.41) ms, (11.78 +/- 2.76) ms, P < 0.01, (8.76 +/-1.94) ms, P < 0.05 and (6.41 +/- 1.32) ms respectively. The inactivation of TTX-R sodium channel tail currents was also significantly delayed by Fen. The tau(Na) of the tail currents at doses of 10, 50, 100 micromol/L Fen and control groups were 6.11 +/- 0.52 (P < 0.05), 7.82 +/- 0.82 (P < 0.05), 7.23 +/- 1.09 (P < 0.05) and (4.91 +/- 0.97) ms separately. As compared with TTX-R sodium channel, the TTX-S sodium channel was less responsive to Fen exposure, which only led to slowly decay TTX-S sodium tail currents. There was no any effect of Pho on the TTX-S and TTX-R sodium channels. The mixed treatment of a Pho and Fen did not show joint effect on the sodium currents. CONCLUSION: Both the peak and tail currents are changed by Fen, however, Fen has more remarkable effects on TTX-R than on TTX-S sodium channel. The combined exposure to Pho and Fen shows no joint effect on the sodium channel.
OBJECTIVE: To investigate the indication and result in hemangioma in oral and maxillofacial region with Pingyangmycin injection. METHODS: 1282 patients (554 males and 728 females) with hemangioma in oral and maxillofacial region have been treated in our hospital during the 10-year period from May 1990 to March 1999. The patients range between 0.5-84 years old. Lip, cheek and tongue were usually involved. 1211 patients were treated with injection of Pingyangmycin(about 0.89 mg/ml) and dexamethasone (about 0.55 mg/ml), 1 time/1-2 weeks. RESULTS: The curative rates of cavernous hemangioma and strawberry hemangioma were 93.87% and 84.90%, but that of plexiform hemangioma was 22.22% and those of portwine stain and central hemangioma of the jaws were 0%, respectively. Serious complications associated with Pingyangmycin injection, such as pulmonary fibrosis were not seen. CONCLUSION: Injection of Pingyangmycin is selective primary method for cavernous and strawberry hemangioma treatment.
1.5 kb of otsA gene encoding trehalose synthase has been cloned by PCR amplification. The DNA fragment was ligated to multi-copy vector and transformed to otsBA deleted and otsA deficient strains of E. coli separately. The transformants exhibited growth as well as the otsBA+ wild type on medium containing 0.5 mol/L NaCl. Trehalose was synthesized and accumulated in the transformed cells under osmotic pressure, which was determined by thin layer chromatograph. The results confirmed that otsA gene was functionally expressed in the recipient strains. These studies suggested that engineering otsA gene and trehalose accumulation into crop plants may improve drought and salinity tolerance.
The factors affecting Bacillus stearothermophilus WF146 for thermophilic protease producing have been investigated, more than 600 units of enzyme in 1 mL of fermented culture could be achieved under suitable condition. The protease had a molecular weight around 34 kD estimated by SDS-PAGE, and functioned optimally at pH 8.0 and 80 degrees C, respectively. In addition, the enzyme exhibited high temperature tolerance and was stable at a wide range of pH, and Ca2+ played a key role for the stability of the enzyme. While the protease activity of the enzyme was strongly inhibited by PMSF, DFP and IAA, and was not affected by DTT.
Potential roles of trophins in the normal and injured spinal cord are largely undefined. However, a number of recent studies suggest that adult spinal cord expresses neurotrophin receptors and responds to the neurotrophins, brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3), particularly after injury. The data indicate that trophins may enhance regrowth after damage and may represent a new therapeutic approach to injury. Neurotrophins are reportedly present in the spinal cord, but the cellular localization is unknown. This information is critical to begin delineating mechanisms of actions. To approach this problem, we examined whether spinal cord glia express BDNF and NT3 in vivo and have begun to define cellular distribution. Specific antibodies directed against the neurotrophins were utilized to visualize neurotrophin protein. Initial studies indicated that small cells in the white matter of adult rat spinal cord express BDNF and NT3. Large neurotrophin-positive neurons were also identified in the ventral cord. To identify the neurotrophin-positive cells, co-localization studies were performed utilizing neurotrophin polyclonal antisera together with monoclonal antibodies directed against the astrocyte marker, glial fibrillary acidic protein (GFAP). In the white matter of adult spinal cord, GFAP-positive and GFAP-negative cells expressed BDNF and NT3. Our study suggests that astrocyte and non-astrocyte cells provide trophic support to the adult spinal cord.
Five highly excited (1)Sigma(+)(g) states of Na(2) were observed for the first time by pulsed optical-optical double resonance (OODR) fluorescence excitation spectroscopy. Three of the five states are assigned to the 6svarsigma (1)Sigma(+)(g), 6dvarsigma (1)Sigma(+)(g), and 7dvarsigma (1)Sigma(+)(g) Rydberg states. The other two states are assigned to doubly excited (1)Sigma(+)(g) states. Copyright 1999 Academic Press.
With a sensitive space-charge-limited diode ionization detector, we studied 8-10svarsigma, 8-10dvarsigma (1)Sigma(+)(g), and 10-15dpi (1)Pi(g) Rydberg states of Na(2) and obtained their molecular constants for the first time. It is the first successful example of a diode ionization detector that is used in a pulsed OODR molecular spectroscopy experiment. Copyright 1999 Academic Press.
Regulation of transcription occurs through complex interactions of RNA polymerase and accessory proteins with specific DNA sequences and with each other. The DNA template topology influences the interaction of RNA polymerase with the promoter and its response to repressors, activators and the intracellular milieu through the formation of altered DNA structures or of nucleoprotein complexes. Recent developments on the role of DNA structures in transcription regulation are discussed.
A typical apoptosis of BTI-Tn-5B1-4 (Hi5) cells induced by Heliothis armigera single capsid nucleopolyhedrovirus (HaSNPV) infection was completely suppressed by coinfection with Trichoplusia ni multicapsid nucleopolyhedrovirus polyhedron-negative recombinant (TnMNPV-SVI- G) (OCC-) at a low multiplicity of infection (6.5 x 10(-2)). To determine whether TnMNPV p35 alone was sufficient to inhibit the apoptosis, two recombinant plasmids containing the early promoter of p35, or the very late promoter of TnMNPV polh were constructed to study p35 function by transient expression assay. It was shown that expression of p35 alone could partially prevent HaSNPV-induced apoptosis but did not facilitate HaSNPV replication in Hi5 cells. The data suggests that both P35 of TnMNPV and other unknown gene products are required for the suppression of apoptosis and facilitation of HaSNPV replication in Hi5 cells.