Biomedical subjects

H Lü

Publications and source records attributed to H Lü.

At least 19 recordsLinked to original sources

PubMed2005

General nonextremal rotating black holes in minimal five-dimensional gauged supergravity.

We construct the general solution for nonextremal charged rotating black holes in five-dimensional minimal gauged supergravity. They are characterized by four nontrivial parameters: namely, the mass, the charge, and the two independent rotation parameters. The metrics in general describe regular rotating black holes, providing the parameters lie in appropriate ranges so that naked singularities and closed timelike curves (CTCs) are avoided. We calculate the conserved energy, angular momenta, and charge for the solutions, and show how supersymmetric solutions arise in a Bogomol'nyi-Prasad-Sommerfield limit. These have naked CTCs in general, but for special choices of the parameters we obtain new regular supersymmetric black holes or smooth topological solitons.

Journal Article↗

PubMed2005

New Einstein-Sasaki spaces in five and higher dimensions.

We obtain infinite classes of new Einstein-Sasaki metrics on complete and nonsingular manifolds. They arise, after Euclideanization, from BPS limits of the rotating Kerr-de Sitter black hole metrics. The new Einstein-Sasaki spaces L(p,q,r) in five dimensions have cohomogeneity 2 and U(1) x U(1) x U(1) isometry group. They are topologically S(2) x S(3). Their AdS/CFT duals describe quiver theories on the four-dimensional boundary of AdS(5). We also obtain new Einstein-Sasaki spaces of cohomogeneity n in all odd dimensions D = 2n + 1 > or = 5, with U(1)(n + 1) isometry.

Journal Article↗

PubMed2005

Brane worlds in collision.

We obtain an exact solution of the supergravity equations of motion in which the four-dimensional observed Universe is one of a number of colliding D3 branes in a Calabi-Yau background. The collision results in the ten-dimensional spacetime splitting into disconnected regions, bounded by curvature singularities. However, near the D3 branes the metric remains static during and after the collision. We also obtain a general class of solutions representing p-brane collisions in arbitrary dimensions, including one in which the universe ends with the mutual annihilation of a positive-tension and a negative-tension 3 brane.

Journal Article↗

PubMed2004

Rotating black holes in higher dimensions with a cosmological constant.

We present the metric for a rotating black hole with a cosmological constant and with arbitrary angular momenta in all higher dimensions. The metric is given in both Kerr-Schild and the Boyer-Lindquist form. In the Euclidean-signature case, we also obtain smooth compact Einstein spaces on associated S(D-2) bundles over S2, infinitely many for each odd D>/=5. Applications to string theory and M-theory are indicated.

Journal Article↗

PubMed2002

M-theory conifolds.

Seven manifolds of G2 holonomy provide a bridge between M-theory and string theory, via Kaluza-Klein reduction to Calabi-Yau six manifolds. We find first-order equations for a new family of G2 metrics D7, with S3 x S3 principal orbits. These are related at weak string coupling to the resolved conifold, paralleling earlier examples B7 that are related to the deformed conifold, allowing a deeper study of topology change and mirror symmetry in M-theory. The D7 metrics' nontrivial parameter characterizes the squashing of an S3 bolt, which limits to S2 at weak coupling. In general the D7 metrics are asymptotically locally conical, with a nowhere-singular circle action.

Journal Article↗

PubMed2001

[An analysis on the forearm bone mass density of rural female and the environmental risk factors].

The distribution of distal and proximal forearm bone mass densities (BMD) with age was discribed and the environmental risk factors of rural female analyzed. A group of 1432 rural female aged 15 and over were sellected. Their demographic characteristics, living and eating habit were obtained by standardized questionnaire. The distal and proximal forearm bone mass density were measured by peripheral dual-energy X ray absorptionmetry (pDEXA). The results showed that the distal and proximal forearm BMDs were increased with age before age 25 and 30 respectively, and reached the peak value at age 30-35. The distal forearm bone density decreased significantly at age 40 while the proximal forearm BMD decreased at age 45. Bone loss rate of the two bone sites was increased significantly at age 50 and reached the peak value at age 55-60. Only the the density of proximal forearm bone, and the year of menopause was the main cause of low bone density. Body weight was the positive factor for bone density at age less than 60. Height only positively affected the proximal forearm bone of those at age 30-45. More ever, drinking tea, parity and educational status may affect distal forearm bone in certain age group while parity, educational status, occupation and marital status were possible risk factors of proximal forearm BMD. It is concluded that environmental risk factors of BMD varied with bone site and age. The prevention of low BMD must rely on subject's age and bone site. The surveillance of low bone density must put the emphasis on spony bone.

Adult↗

PubMed2001

Potentiation of docetaxel antitumor activity by batimastat against mouse forestomach carcinoma.

OBJECTIVE: To improve the treatment of tumors, we studied the combined effects of docetaxel and batimastat (BB-94) on mouse forestomach carcinoma (MFC), and compared them with doxorubicin. METHODS AND RESULTS: In vitro, growth curve analysis, MTT assay and clonogenic assay used to determine the cytotoxic effect of docetaxel or/and BB-94 on MFC cell showed that docetaxel but not BB-94 had a significant cytotoxicity, and the effect of docetaxel wasn't enhanced by BB-94. In early stage MFC tumor model, obvious antitumor effect of docetaxel or doxorubicin given i.v. at maximum tolerated dose (MTD, docetaxel: 20 mg/kg; doxorubicin: 6 mg/kg) every 4 days for 3 injections (q4d x 3), even that of BB-94 (30 mg/kg i. p. qd x 20) was observed. Tumor growth inhibition was greater for docetaxel-batimastat (96.0%) than for doxorubicin-batimastat (88.0%), docetaxel (89.0%), doxorubicin (68.0%) and BB-94 (33.0%), and the effect of docetaxel could be potentiated by BB-94. Docetaxel also showed activity against advanced stage MFC tumor in dose-dependent manner, and was more effective at MTD than doxorubicin with 4/5 regressions, 46.5 days tumor growth delay and 2.8log(10) tumor cell kill. CONCLUSION: Our results suggest that in the MFC model with dose and schedule used, docetaxel is an effective cytotoxic new drug against MFC tumor and BB-94 enchances the antitumor activity of docetaxel.

Animals↗

PubMed2000

Cytotoxic effects of 5-fluorocytosine on melanoma cells transduced with cytosine deaminase gene.

To investigate the cytotoxic effects of 5-fluorocytosine on melanoma cells genetically modified with cytosine deaminase gene, the gene was transduced into the tumor cells with the retroviral method. The cytotoxicity effects of 5-fluorocytosine on the tumor cells were measured with the MTT assay and clonogenic assay. It was found that the prodrug 5-fluorocytosine had significant cytotoxic effects on melanoma cells transduced with cytosine deaminase in vitro. The IC50 value of 5-fluorocytosine on transgenic and nontransgenic melanoma cells was 572 microg/mL(-1) and 3870 microg/mL(-1), respectively. Our experiment demonstrated the potential value of the cytosine deaminase gene/5-fluorocytosine system in the treatment of melanoma.

3T3 Cells↗

PubMed2000

Potentiation of docetaxel antitumor activity by batimastat against mouse forestomach carcinoma.

Docetaxel is a chemical compound belonging to the taxoid class of anticancer agents. Batimastat (BB-94) is the first matrix metalloproteinase inhibitor entering clinical trials. To improve the treatment of tumors, we studied the combined effects of docetaxel and batimastat on mouse forestomach carcinoma (MFC), and compared them with doxorubicin. In vitro growth curve analysis, MTT assay, and clonogenic assay were used to determine the cytotoxic effect of docetaxel or/and BB-94 on MFC. They showed that docetaxel, but not BB-94, had a significant cytotoxicity and that the effect of docetaxel was not enhanced by BB-94. In an early stage MFC tumor model, an obvious antitumor effect of docetaxel or doxorubicin given iv at maximum tolerated dose (MTD) was observed. Tumor growth inhibition was greater for docetaxel + BB-94 (96.0%) than for doxorubicin + BB-94 (88.0%), docetaxel (89.0%), doxorubicin (68.0%), and BB-94 (33.0%). Docetaxel showed activity against advanced stage MFC tumor in a dose-dependent manner and was more effective at MTD than doxorubicin, with 4/5 regression, 46.5 days tumor growth delay, and 2.8 log10 tumor-cell kill. Our results suggest that docetaxel is an effective new cytotoxic drug against MFC tumor and that BB-94 enhances the antitumor activity of docetaxel in the dose and schedule used.

Animals↗

PubMed2000

[Clinical analysis of 13 infected total knee replacements].

OBJECTIVE: To investigate the cause, treatment and its result of infected total knee replacements (TKRs). METHODS: Between 1987 and 1999, 13 infected TKRs in 13 patients were treated with surgical debridement and one-stage or two-stage reimplantation. The preoperative average ROM of knees was 55 degrees and the average Hospital for Special Surgery (HSS) knee score was 36.5 points. Clinical results were evaluated after average follow-up for 3 years and 5 months. We analyzed the factors for TKR infection. RESULTS: No recurrent infection was noted, and pain was significantly alleviated in all patients. The average ROM of knees was 85 degrees and the average HSS knee score was 73.5 points. CONCLUSIONS: The high risk factors for TKR infection are rheumatoid arthritis, steroid administration, associated diabetes mellitus, hinged prosthesis and previous knee surgery. Early surgical debridement with intravenous antibiotics is necessary as soon as deep infection is detected. Two-stage reimplantation is more effective in eradicating deep infection than single debridement or one-stage reimplantation.

Adult↗

PubMed2000

[Risk factors for nosocomial infections after total knee replacement].

OBJECTIVE: To investigate prevalence and risk factors of nosocomial infections in patients with total knee replacement. METHODS: From August 1993 to October 1998, total knee replacement was performed on 363 patients (503 knees). The difference of nosocomial infection rates was statistically analyzed in comparison with different age, primary disease, and associated disease groups. RESULTS: No statistically significant difference was observed in nosocomial infection when compared rheumatoid arthritis with osteoarthritis, bilateral total knee replacement (TKR) with unilateral TKR and different ages. However, the higher nosocomial infection rate was related to the following factors: revision surgery, steroid administration and diabetes urinary infection. 28 female patients demonstrated higher urinary infection rate than that in other systems. CONCLUSIONS: Nosocomial infection rate of TKR in rheumatoid cases is related to steroid administration, accompanying diabetes mellitus, previous knee surgery, aged women and retention of urinary catheter. It is feasible to prevent nosocomial infection by controlling the above-mentioned risk factors.

Adult↗

PubMed2000

[Posterior atlantoaxial facet screw fixation in rheumatoid arthritis].

OBJECTIVE: To clarify the characteristics of the clinicopathological factors in cases of atlantoaxial instability due to rheumatoid and to introduce a new method for the treatment of this disease. METHODS: Fifteen patients with atlantoaxial instability due to rheumatoid were treated with posterior facet screws to obtain immediate rigid fixation of C(1 - 2). In this series of patients, screw fixation was augmented with an interspinous C(1 - 2) strut graft which was wired in place to provide three-point stabilization and to facilitate bone fusion. RESULTS: In each patient fixation was satisfactory, and C(1 - 2) alignment and stability were restored without complication due to instrumentation. All patients showed osseous union (a mean follow-up period of 10 months; range 6 - 14 months). CONCLUSION: Posterior atlantoaxial facet screw fixation provides immediate three-dimension rigid fixation of C(1 - 2) that is biomechanically superior to wiring or other fixation.

Adult↗

PubMed2000

[The identification and cloning of human ubiquitin binding enzyme cDNA].

OBJECTIVE: To identify and clone the gene encoding human ubiquitin binding enzyme and study its expression spectrum. METHODS: According to the sequence of human EST, which is highly homologous to the mouse ubiquitin conjugating enzyme (E2), primers used for library screening were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by making use of bioinformatics and its expression spectrum was studied by using multiple-tissue Northern blot. RESULTS: Two cDNA clones encoding human ubiquitin conjugating enzyme were isolated and identified. Both containing the ubiquitin conjugating domain, they were 88% identical in amino acid sequences and found to be isoforms of each other with only an exon excised from the short sequence. They belonged to a highly conserved, and widely expressed E2 enzyme family. Northern blot showed that they were expressed exclusively in heart, placenta, and pancreas while no transcripts could be detected in brain, lung, liver, skeletal muscle, or kidney. CONCLUSIONS: The gene encoding human ubiquitin binding enzyme is expressed under both temporal and spatial control. As a key enzyme in the degradation of proteins, ubiquitin conjugating enzymes play a central role in the expression regulation on the level of post-translation.

Amino Acid Sequence↗

PubMed1998

[Detection of type 6 human herpesvirus (HHV-6) specific DNA sequence in lymphoma tissues by PCR].

OBJECTIVE: To study the relationship between human herpesvirus-6 (HHV-6) and lymphoma in China. METHODS: The specimens of paraffin-embedded lymphoma tissue, leukemia cell lines and normal blood donor peripheral blood lymphocytes(PBL) were examined for the presence of HHV-6 DNA sequence by polymerase chain reaction (PCR). RESULTS: Of the 52 cases lymphoma studied, HHV-6 DNA sequence was detected in 21 cases; of 43 normal PBL, HHV-6 DNA sequence was detected in 8 cases. The difference was statistically significant (P < 0.05). HHV-6 DNA sequence was also present in two leukemia cell lines. CONCLUSION: The results suggest that HHV-6 may be related to lymphoma in China.

DNA, Viral↗

PubMed1997

Locomotory phenotypes of human tumor cell lines and T lymphocytes in a three-dimensional collagen lattice.

Active cellular locomotion is a feature of such diverse cell types as lymphocytes and cancer cells. The locomotory phenotype of a cell should ultimately reflect the biochemical basis of different migratory strategies. We investigated the locomotory behavior of five epithelial cell lines and one non-epithelial human cell-line as well as human CD4+ T lymphocytes in a three-dimensional collagen type I matrix using time-lapse video microscopy and computer assisted cell-tracking. Migration velocity was up to 70 times lower in tumor cells (0.1-0.3 microm/min) as compared to T lymphocytes (7-7.5 microm/min), whereas the percentage of spontaneously active cells was up to twice as high in tumor cells (80-90%) in comparison to T lymphocytes (54%). Persistence, i.e. the degree of roaming, varied appreciably between the different cell types. In conclusion, velocity and persistence may describe distinct migration strategies in different cell types, i.e. discerning T cell migration from tumor cell invasion.

Cell Movement↗

PubMed1997

Migration and gap junctional intercellular communication determine the metastatic phenotype of human tumor cell lines.

Gap junctional intercellular communication (GJIC) as well as cell migration play an essential role in the metastatic cascade of human tumors. We show a dependence of metastatogenic phenotypes of human tumor cells (cell lines T 24, SCC-25, MDA-MB-361 and SK-BR-3) from the GJIC and the migration activity. The GJIC was studied by microinjection of the fluorescent dye Lucifer Yellow (LY) and cell migration was studied by investigating the locomotion of the tumor cells in 3-dimensional collagen matrices. Diminished GJIC seems to be more influential for the metastatic phenotype than modulation of the locomotory behavior of the tumor cells.

Breast Neoplasms↗

PubMed1997

[The study on analgesic effect of local-release delivery system--Huangjiabang].

Laboratory investigation was made on analgesic effect of local release delivery system, Huangjiabang, which mainly includes Chinese medical herbs. Through the application of twisting-body and thermal-plate experiments on white rats. The result showed that the pain threshold was markedly elevated (P < 0.05, P < 0.001) after the rats were fed with Huangjiabang 125 mg/kg or 250 mg/kg body weight, and the number of twisting body's animals significantly decreased (P < 0.001). The analgestic mechanism of Huangjiabang delivery system relates to its effect of invigorating the circulation of blood and accelerating the stasis assimilation, remitting the inflammation.

Analgesics, Non-Narcotic↗

PubMed1997

[Environmental pollution, human exposure and its health effect of sodium pentachlorophenate in schistosomiasis prevalent area].

Sodium pentachlorophenate (Na-PCP) has been used in China for years as an molluscacide to kill oncomelania, which is an intermediate host of Schistosome. To evaluate the effects of its long-term successive usage on environment, human exposure and health, studies were carried out in Sichuan, Jiangxi, Jiangsu and Fujian provinces, with a time gap of more than one month between sample collection and last spray of Na-PCP. Results indicated that PCP contents in surface water, soil, sediment, animals and plants were significantly higher in studied areas than in control areas. The daily intake and the content in urine of PCP were also sigificantify higher in studied areas. But, there was no difference on physical and biochemical examinations except that a 22%-28% decrease of blood cholinesterase activity was found in studied areas. The health effect of impurities in Na-PCP, dioxins and furans, was assessed and discussed.

Animals↗