Biomedical subjects

X Song

Publications and source records attributed to X Song.

At least 91 records · Page 5Linked to original sources

PubMed1999

[Study on the induction of xenogeneic tolerance of rat to mouse bone marrow transplantation].

OBJECTIVE: To establish an effective protocol for potential clinical usage in inducing donor-specific tolerance across xenogeneic barriers. METHODS: C57BL/6 (B6) mice were conditioned with 5 Gy sublethal total body irradiation (TBI), followed by infusion of 4 x 10(7) Lewis rat bone marrow cells on day 0, then were intraperitonially administered 150 mg/kg cyclophosphamide (CP) on day 2. Recipients were characterized for engraftment with xenogeneic bone marrow cells by using fluorescence activated cell sorter (FACS) to determine the percentage of rat origin cells in the peripheral blood lymphocytes(PBL), splenic and thymic lymphoid cells on day 30, 60 and 90. Mixed lymphocyte reaction (MLR) and delayed type hypersensitivity (DTH) assay were performed on day 30 to examine the tolerance status. RESULTS: Rat lymphoid chimeras were reliable present in the tolerant B6 mice for more than 3 months. B6 recipients were specifically tolerant to host xenoantigens in MLR and DTH assays, but were still immunocompetent to MHC-disparate third party BALB/c mouse or DA rat stimulator cells. CONCLUSION: A durable rat to mouse xenogeneic bone marrow transplantation tolerance was achieved in this modal.

Animals↗

PubMed1999

[Regulation of adherence to serum-coated hydroxyapatite by Streptococcus sanguis].

OBJECTIVE: To investigate the effects of pH and calcium iron on adhesion of Streptococcus sanguis to serum-coated hydroxyapatite. METHODS: The adhesion model in vitro established by Clark W. B. in 1977 was used to quantify adsorptive cells through [3H] thymidine labelling. RESULTS: The cpm values between different pH groups showed significant differences. Also, there were significant differences of cpm values between calcium groups and control group. CONCLUSION: Either pH or calcium iron has obvious effect on adherence of Stroptococcus sanguis to serum-coated hydroxyapatite. The findings suggest that regulating pH and concentration of calcium iron can help to change colonization on teeth surfaces by Streptococcus sanguis in periodontal circumstance.

Animals↗

PubMed1999

[The application of chopping method for phacoemulsification of hard nucleus cataract].

OBJECTIVE: The study was designed to investigate the application of chopping method for phacoemulsification of hard nucleus cataract. METHODS: Modified stop and chop technique was used to emulsify the hard nucleus cataract. The degree of nuclear hardness in 80 eyes was grade IV. RESULTS: Postoperatively, the visual acuity with correction was >or= 0.9 in 76.25% at 3 months. There were mild corneal edema in 8 cases, moderate corneal edema in 2 cases and posterior capsular rupture in 1 case. CONCLUSION: The modified stop and chop technique enables the tenacious nuclear plate to rupture easily, thus the stress on the zonules and capsule can be decreased, and in the mean time the technique needs less phaco energy and time.

Aged↗

PubMed1999

[Prevalence of blindness among adults aged 50 years or above in Shunyi county of Beijing].

OBJECTIVE: To estimate the prevalence of blindness among older adults aged >or= 50 years in Shunyi county of Beijing, China. METHODS: Cluster sampling was used in randomly selecting individuals aged >or= 50 years in 28 villages in Shunyi county in fall, 1996. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. RESULTS: 5,555 individuals were enumerated. The response rate was 91.5%. In this population, the prevalence of blindness was 1.7% defined as pinhole visual acuity < 0.05 in both eyes; or 2.8% were blind, defined as presenting visual acuity < 6/60 in both eyes. Blindness was associated with older age and female gender. The principal cause of blindness in eyes was cataract. CONCLUSIONS: The prevalence of blindness was decreased 35.8% after ten year active eye-care program in the survey area. However, cataract blindness continues as a significant problem among elderly, especially females, in this population sample of rural area.

Age Factors↗

PubMed1999

[Neurilemmoma of the nasal cavity and paranasal sinuses (report of 12 cases)].

OBJECTIVE: To further understand the neurilemmoma of nose. METHOD: 12 cases of neurilemmomas of the nasal cavity and paranasal sinuses were treated successfully by operation, 2 cases of malignant change lesions were treated by extensive resection and radiation. RESULT: 11 in 12 cases were followed up. 9 cases were cured and no any serious complications, 2 cases of malignant tumor were died. CONCLUSION: Early stage diagnosis is important. CT scan should be made as essential examination, complete surgical resection is the choice of treatment for primary lesions; malignant change lesions should be treated by combined operation with radiation.

Adolescent↗

PubMed1999

[The treatment to esophagus stricture with Ni-Ti shape memory alloy stand(with the report of 19 clinical cases)].

OBJECTIVE: To discuss the use of Ni-Ti shape memory alloy stand in treating the stricture of esophagus. METHOD: After finding the stricture part of esophagus under X-ray, the metal guide string was put through the esophagoscope. Dilatation of esophagus was performed firstly. Then the inserting instrument, which has the Ni-Ti shape memory alloy stand inside, was put through the stricture part along the metal guide string and the stand which can return to its original shape automatically was released. Barium meal examination of esophagus was performed after the operation to determine the site of the stand and to realize the smooth degree of esophagus. RESULT: All 19 patients got a successful operation at one time. They swallowed freely after the operation. The effective rate was 100%. CONCLUSION: Ni-Ti shape memory alloy stand can dilate the stricture of esophagus quickly, improve swallowing function obviously. The operation can be easily performed. The therapeutic effectiveness is reliable, and there is no serious complication. This can be used as a routine method in treating the stricture of esophagus.

Adolescent↗

PubMed1999

[The treatment of stricture of larynx and trachea with Ni-Ti shape memory alloy stand].

OBJECTIVE: To evaluate the use of Ni-Ti shape memory alloy stand in the treatment of stricture of larynx and trachea. METHODS: The clinical materials of 14 patients were analyzed. All patients had stricture of larynx and trachea and accepted the treatment with Ni-Ti shape memory alloy stand. RESULTS: All patients breathed freely after the operation, and the trachea fistula was closed at the time of operation. The follow-up survey for these patients lasted for 2 to 12 months. None of the patients had signs of the stricture of the respiratory tract. The short-term effective rate was 100%. CONCLUSION: Ni-Ti shape memory alloy stand can expand the stricture of larynx and trachea quickly and thus improve the breath effectively. It can be used as a routine method in the treatment of stricture of larynx and trachea.

Adult↗

PubMed1998

Determination of chlorinated acid herbicides and related compounds in water by capillary electrophoresis-electrospray negative ion mass spectrometry.

Capillary electrophoresis electrospray negative ion mass spectrometry was investigated for the determination of chlorinated acid herbicides and several phenols in water. Sixteen analytes were separated as their anions in less than 40 min with a buffer consisting of 5 mM ammonium acetate in isopropanol-water (40:60, v/v) at pH 10. A sample stacking technique was used to provide lower detection limits and a fortified drinking water sample was made pH 10 and analyzed without further processing. Quantitative analyses with an internal standard gave recoveries in the 91-124% range and replicate measurements of a calibration standard gave relative standard deviations in the range of 3-10%.

Electrophoresis, Capillary↗

PubMed1998

Seismic evidence for an inner core transition zone

Seismic waves that traverse Earth's inner core along north-south paths produce unusually broad pulse shapes at long periods (compared with waves along east-west paths) and reflections from below the inner core boundary at short periods. The observations provide compelling evidence for a seismic velocity discontinuity along north-south paths about 200 kilometers below the inner core boundary separating an isotropic upper inner core from an anisotropic lower inner core. The triplication associated with such a structure might be responsible for reported waveform complexity of short-period inner core arrivals along north-south paths and, if the depth of the boundary is laterally variable, their large travel-time variation.

Journal Article↗

PubMed1998

Systemic exposure to irradiated apoptotic cells induces autoantibody production.

During apoptotic cell death, cell surface ligands initiate phagocytosis of the dying cell. Clearance of these apoptotic cells is thought to occur without an immune response. Since a number of autoantigens are located at the cell surface or within apoptotic blebs, we examined whether exposure of mice to syngeneic apoptotic cells by the intravenous route could induce autoantibody production. Normal mice injected with syngeneic apoptotic thymocytes developed antinuclear autoantibodies and anticardiolipin and anti-ssDNA antibodies. The autoantibody levels were generally lower than those observed in MRL/Faslpr mice and were transient. Surprisingly, six out of six immunized mice demonstrated immunoglobulin G deposition in the glomeruli several months after immunization. These findings indicate that systemic exposure to apoptotic cells can induce an immune response in normal mice, and may help to explain antigen selection and initiation of the immune response in diseases characterized by increased rates of apoptosis such as AIDS and, possibly, systemic lupus erythematosus.

Animals↗

PubMed1998

Modeling the developmental neurotoxicity of chlorpyrifos in vitro: macromolecule synthesis in PC12 cells.

Exposure to apparently subtoxic doses of chlorpyrifos during late stages of brain development affects cell acquisition through a mixture of cholinergic and noncholinergic mechanisms. In the current study, we modeled these effects in vitro using rat pheochromocytoma (PC12), a cell line that, upon nerve-growth factor (NGF)-induced differentiation, develops the appearance and function of cholinergic target neurons, including the expression of cholinergic receptors. In the undifferentiated state (no NGF), chlorpyrifos evoked an immediate (1 h), robust, concentration-dependent inhibition of DNA synthesis as evaluated by [3H]thymidine incorporation, with a threshold of 0.5-1.5 microg/ml. Continuous exposure for up to 24 h maintained the same degree of inhibition. The effects were selective for DNA synthesis, as much smaller inhibitions were found for synthesis of RNA or protein. In contrast, direct cholinergic stimulation of the cells by 100 microM nicotine had much smaller effects on DNA synthesis. Moreover, the effects of chlorpyrifos on DNA synthesis could not be blocked by nicotinic or muscarinic antagonists, confirming that the effects were not mediated primarily through cholinergic hyperstimulation consequent to cholinesterase inhibition or to direct receptor-mediated effects. When PC12 cells underwent NGF-induced differentiation, the rate of cell replication fell dramatically and neurite extension was evident both from morphological examination and from biochemical markers (increased protein:DNA ratio). After introduction of NGF, chlorpyrifos maintained its ability to inhibit DNA synthesis acutely. However, the ability to inhibit RNA and protein synthesis initially intensified and then disappeared, indicating a shift in macromolecular targets as differentiation proceeded. We also tested the effects of long-term exposure to chlorpyrifos during the process of NGF-induced differentiation. Continuous chlorpyrifos exposure resulted in severe reductions in macromolecule synthesis and a deficit in the total number of cells, effects similar to those seen with chlorpyrifos treatment in vivo. At the highest concentrations, neurite extension was also inhibited. Our results suggest that chlorpyrifos can interact directly with developing neural cells to inhibit replication and neuritic outgrowth.

Animals↗

PubMed1998

Rhythmicity of torpor in a marsupial hibernator, the mountain pygmy-possum (Burramys parvus), under natural and laboratory conditions.

Circadian rhythms have been observed in most mammals, but their importance and function remain controversial with respect to daily cycles during hibernation. We investigated the timing of arousals from and entries into hibernation for both free-living and captive mountain pygmy-possums (Burramys parvus). Under both natural and laboratory conditions most arousals and entries were entrained with the light-dark cycle. Entries occurred mainly during the night and arousals preferably around dusk, which coincides with the onset of the normal activity phase for the nocturnal pygmy-possums. This entrainment prevailed throughout the hibernation season although only the laboratory animals were constantly subjected to photoperiodic stimuli, whereas under natural conditions hibernacula are shielded from photic cues and diurnal temperature fluctuations. Nevertheless, possums left their hibernacula frequently throughout winter and were occasionally trapped close to the snow surface suggesting that during the periods of post-arousal normothermia they can be exposed to environmental stimuli. It thus appears that the synchronisation with the photocycle was governed by a temperature-compensated circadian clock which was reset periodically during short activity periods. For the mountain pygmy-possum, entrainment with the photocycle probably has two functions: 1. Entrainment ensures that foraging bouts during the hibernation season remain synchronised with the dark phase. 2. Information about the prevailing climatic conditions sampled during short activity periods enables them to time final spring emergence from hibernation when snow melt begins and ensures that the breeding season can commence as early as possible.

Animals↗

PubMed1998

Temperature selection and use of torpor by the marsupial Sminthopsis macroura.

Many small mammals display daily torpor to minimize energy expenditure during the rest phase when faced with unfavorable environmental conditions. However, given a choice of thermal environments, it is not clear whether these daily heterotherms select ambient temperatures that minimize metabolic rates during torpor or ambient temperatures that minimize metabolic rates during normothermia. It is also not clear whether they prefer being normothermic or torpid. In this study, we investigated temperature selection, activity patterns, body temperature patterns, and the use of torpor in Sminthopsis macroura in a thermal gradient when food was freely available or restricted. Animals employed torpor regularly immediately after cessation of activity even when excess food was provided. Nevertheless, they selected high ambient temperature near the zone of thermoneutrality during both normothermia and torpor. Reduced food supply did not affect either temperature preference or total activity, but it did result in significantly prolonged torpor bouts. In addition, it lowered the daily minimum body temperature during torpor by about 2 degrees C. Our study shows that S. macroura selected a high ambient temperature to reduce energy costs during normothermia. Nevertheless, daily torpor was frequently employed at the high temperature, especially when food was restricted.

Animals↗

PubMed1998

1Alpha,25-dihydroxyvitamin D3 and phorbol ester mediate the expression of alkaline phosphatase in NB4 acute promyelocytic leukemia cells.

Both 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] and phorbol 12-myristate 13-acetate [PMA] are cytodifferentiation agents regulating myeloid cell line differentiation along the monocyte/macrophage pathway. Alkaline phosphatase (ALP) activity has been reported to be absent or present at low levels in monocytes/macrophages. In the present study, the acute promyelocytic leukemia cell line (NB4) was found to undergo monocyte/macrophage differentiation and strongly express ALP activity after exposure to the combination of 1alpha,25(OH)2D3 and PMA treatment. The ALP stimulation was both dose- and time-dependent with the ED50 doses for 1alpha,25(OH)2D3 and PMA at 2 x 10(-10) M and 4 x 10(-11) M, respectively. Assessment of the cell morphology via cell adherence, phagocytosis and ALP staining confirmed that NB4 cells treated by 1alpha,25(OH)2D3 plus PMA showed macrophage characteristics, but were also strongly stained with ALP. The present study is the first report that NB4 cells express ALP activity as a consequence of combination treatment with 1alpha,25(OH)2D3 and PMA.

Alkaline Phosphatase↗

PubMed1998

Modified bilateral cleft lip repair with orbicularis reconstruction and prolabial self-elongation.

PURPOSE: This article describes the details of a modified method for bilateral cleft lip repair and presents some examples of patients whose condition was repaired by this technique. PATIENTS AND METHODS: Sixty-five patients ranging in age from 2 to 5 years were treated with this modified procedure. The method was characterized by prolabial lengthening and reconstruction of the orbicularis oris muscle in one stage. RESULTS: Satisfactory results were achieved with this method. The Cupid's bow and the central tubercle appeared more natural. None of the patients developed dehiscence of the wound. CONCLUSIONS: This modified procedure is of special value for complete bilateral cleft lip patients with a short prolabium. The long-term effect of muscle reconstruction on maxillary growth remains to be evaluated.

Child, Preschool↗

PubMed1998

The use of a chimera HIV-1/HIV-2 envelope protein for immunodiagnosis of HIV infection: its expression and purification in E. coli by use of a translation initiation site within HIV-1 env gene.

A chimera HIV-1/HIV-2 envelope sequence composed of multiple conserved immunodominant epitopes of HIV-1 envelope protein (HIV-1 IIIB: env482-518 + env548-675) and the HIV-2 gp36 immunodominant epitope (env592-603), was constructed and directly over-expressed in E. coli by using a prokaryotic translation initiation sequence contained within the gene of HIV-1 envelope. The recombinant product was purified and applied in antibody-screening assay. The purified chimera antigen reacted with all the thirty-eight HIV-1 positive serum samples, the two HIV-2 serum samples, and had no cross-reaction with all the eighty-eight normal healthy serum sample. The results indicated that this recombinant chimera HIV-1/HIV-2 envelope protein could be useful for diagnostic purposes of HIV infection.

AIDS Serodiagnosis↗

PubMed1998

Stimulation of phosphorylation of mitogen-activated protein kinase by 1alpha,25-dihydroxyvitamin D3 in promyelocytic NB4 leukemia cells: a structure-function study.

Recent studies have shown that 1alpha,25-dihydroxyvitamin D3 [1alpha,25-(OH)2D3] actions in cell growth and differentiation are mediated by both its nuclear receptor (VDRnuc) and its rapid membrane-related effects. In the present study, we investigated the effect of 1alpha,25-(OH)2D3 on p42mapk phosphorylation using human acute promyelocytic leukemia cells (NB4). 1Alpha,25-(OH)2D3 (10[-8] M) significantly increased p42mapk phosphorylation in a time- and dose-dependent manner, with the earliest response detectable at 30 sec. Because 1alpha,25-(OH)2D3 is a conformationally flexible molecule, we have used a series of conformationally locked (6-s-cis vs. 6-s-trans) analogs to evaluate which shape is optimal for activation. Four 6-s-cis-locked analogs (HF, JM, JN, and JP) and two 6-s-trans-locked analog (JB and JD) were studied. HF, JM, JN, and JP all increased p42mapk phosphorylation at 1 and 5 min (10[-8] M), but JB and JD had little effect. Analog HL [1beta,25-(OH)2D3], a specific antagonist for only the rapid effects of 1alpha,25-(OH)2D3, attenuated 1alpha,25-(OH)2D3-induced p42mapk phosphorylation 65-90%. To assess the potential involvement of the VDRnuc in mediating the analog's action, the relative abilities of the analogs to compete with [3H]1alpha,25-(OH)2D3 for binding in vitro to the VDRnuc of NB4 cells was measured. All 6-s-cis analogs bound poorly to VDRnuc (relative competitive index, 0.5-2%) compared with 1alpha,25-(OH)2D3 (relative competitive index, 100%). The present studies demonstrate for the first time that in NB4 cells 1alpha,25-(OH)2D3 rapidly activates the p42mapk pathway, and that this effect can be selectively mediated by analogs that can assume a 6-s-cis conformation.

Calcitriol↗

PubMed1998

[Iatrogenic peripheral nerve injuries and its repair].

In order to investigate the causes, diagnosis, treatment, outcome and prevention of iatrogenic nerve injury in the neck, 8 cases with iatrogenic nerve injuries were analyzed. Among them, 5 cases were accessory nerve injury, 3 cases were brachial plexus injury. All of the cases were treated by surgical methods, including neurolysis, repair by direct suture, nerve graft and transposition. After 1-3 years follow up the effect was excellent in 2 cases who were accessory nerve injury, good in 5 cases, and poor in 1 case who was brachial plexus injury. It was concluded that high responsibility of surgeons and careful manipulation during operation were the key to prevention of nerve injuries.

Accessory Nerve↗