Biomedical subjects

L Bao

Publications and source records attributed to L Bao.

At least 19 recordsLinked to original sources

PubMed2006

Constitutive nitric oxide acting as a possible intercellular signaling molecule in the initiation of radiation-induced DNA double strand breaks in non-irradiated bystander cells.

The initiation and propagation of the early processes of bystander signaling induced by low-dose alpha-particle irradiation are very important for understanding the underlying mechanism of the bystander process. Our previous investigation showed that the medium collected from cell culture exposed to low-dose alpha-particle rapidly induced phosphorylated form of H2AX protein foci formation among the non-irradiated medium receptor cells in a time-dependent manner. Using N(G)-methyl-L-arginine, 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate and N(omega)-nitro-L-arginine (L-NNA) treatment before exposure to 1 cGy alpha-particle, we showed in the present study that nitric oxide (NO(*)) produced in the irradiated cells was important and necessary for the DNA double strand break inducing activity (DIA) of conditioned medium and the generation of NO(*) in irradiated confluent AG1522 cells is in a time-dependent manner and that almost all NO(*) was generated within 15 min post-irradiation. Concurrently, the kinetics of NO(*) production in the medium of irradiated cells after irradiation was rapid and in a time-dependent manner as well, with a maximum yield observed at 10 min after irradiation with electron spin resonance analysis. Furthermore, our results that 7-Nitroindazole and L-NNA, but not aminoguanidine hemisulfate, treatment before exposure to 1 cGy alpha-particle significantly decrease the DIA of the conditioned medium suggested that constitutive NO(*) from the irradiated cells possibly acted as an intercellular signaling molecule to initiate and activate the early process (<or=30 min) of bystander response after low-dose irradiation.

Alpha Particles↗

PubMed2006

Differential expression of synaptoporin and synaptophysin in primary sensory neurons and up-regulation of synaptoporin after peripheral nerve injury.

Synaptoporin and synaptophysin are integral membrane components of synaptic vesicles. The distribution of synaptoporin and its relationship with synaptophysin in sensory afferent fibers remain unclear. In the present study, we showed that in the rat dorsal root ganglia synaptoporin was expressed in subsets of small neurons that contain either calcitonin gene-related peptide or isolectin B4, and was distributed in their afferent terminals in laminae I-II of the spinal cord. Synaptophysin was expressed in 57% of synaptoporin-containing small dorsal root ganglion neurons and in large dorsal root ganglion neurons. In the spinal dorsal horn, synaptophysin-immunolabeling was weak in the afferent fibers in lamina I, outer lamina II and the dorsal part of inner lamina II, but strong in the afferent fibers in laminae III-IV. However, a subpopulation of isolectin B4-positive small dorsal root ganglion neurons expressed both synaptoporin and synaptophysin, and their afferent fibers were mainly distributed in the ventral part of inner lamina II. After peripheral nerve injury, synaptoporin expression was up-regulated in small dorsal root ganglion neurons, and synaptoporin level was increased in their afferent terminals. Thus, synaptoporin and synaptophysin have topographically distinct distributions in afferent fibers. Synaptoporin is a major synaptic vesicle protein in Adelta- and C-fibers in both physiological and neuropathic pain states.

Analysis of Variance↗

PubMed2004

Increased serum C3 levels in Crry transgenic mice partially abrogates its complement inhibitory effects.

Complement receptor 1-related gene/protein y (Crry) is a potent murine complement regulator that inhibits C3 convertases. Transgenic mice that overexpress soluble Crry (sCrry), directed systemically by the metallothionein-I promoter, have been used as an animal model for chronic blockade of complement activation. Recently we have found that alternative pathway (AP) activity in Crry transgenic mice was not inhibited as much as expected. To elucidate the mechanism of this effect, we evaluated the AP activities and levels of sCrry and AP complement components in transgenic and non-transgenic mice. In transgenic mice, expression of sCrry was induced by feeding zinc sulphate solution to 70.1 +/- 42.7 micro g/ml mean serum level. Its corresponding level of purified sCrry inhibited 49% of AP activity of normal mice serum; however, the actual AP activities in transgenic mice were not decreased when compared to non-transgenic mice (130.2 +/- 9.0%versus 113.0 +/- 35.4%). Expressed sCrry was functional, as immunoprecipitation and removal of sCrry from transgenic sera with rabbit anti-Crry polyclonal antibody resulted in enhanced AP activity, consistent with initial levels of sCrry. We then compared the changes to C3, factor B, factor H and factor D serum levels in transgenic and non-transgenic mice after induction of sCrry expression. Of these only C3 was increased after zinc feeding in transgenic mice compared to non-transgenic mice (142.8 +/- 14.1%versus 121.4 +/- 15.1%, P = 0.023). These results suggest that the inhibitory effect of chronic exposure to sCrry is compensated by concomitant alteration in C3 levels. This result also suggests the presence of a complement regulatory protein controls the level of serum C3, which has potential importance in the design and interpretation of studies involving chronic use of complement inhibitors.

Animals↗

PubMed2002

Reproductive fitness in maternal homocystinuria due to cystathionine beta-synthase deficiency.

Early diagnosis and improved treatment are leading to the potential for increased reproductive capability in homocystinuria due to cystathionine beta-synthase (CbetaS) deficiency, but information about reproductive outcome and risk of thromboembolism in pregnancy is limited. To provide further information, clinical and biochemical information was obtained on women with maternal homocystinuria, on their pregnancies and on the offspring. This information included blood sulphur amino acids and total homocysteine, CbetaS gene mutations and developmental and cognitive scores in the offspring. The study involved 15 pregnancies in 11 women, of whom 5 were pyridoxine-nonresponsive and 6 were pyridoxine-responsive. Complications of pregnancy included pre-eclampsia at term in two pregnancies and superficial venous thrombosis of the leg in a third pregnancy. One pregnancy was terminated and two pregnancies resulted in first-trimester spontaneous abortions. The remaining 12 pregnancies produced live-born infants with normal or above-normal birth measurements. One offspring has multiple congenital anomalies that include colobomas of the iris and choroid, neural tube defect and undescended testes. He is also mentally retarded and autistic. A second offspring has Beckwith-Wiedemann syndrome. The remaining 10 offspring were normal at birth and have remained normal. There was no relationship between the severity of the biochemical abnormalities or the therapies during pregnancy to either the pregnancy complications or the offspring outcomes. The infrequent occurrences of pregnancy complications, offspring abnormalities and maternal thromboembolic events in this series suggest that pregnancy and outcome in maternal homocystinuria are usually normal. Nevertheless, a cautious approach would include careful monitoring of these pregnancies with attention to metabolic therapy and possibly anticoagulation.

Adolescent↗

PubMed2001

Adjuvant-induced arthritis: IL-1 beta, IL-6 and TNF-alpha are up-regulated in the spinal cord.

Adjuvant-induced arthritis (AIA) is a widely used animal model of human rheumatoid arthritis (RA). We have previously shown that increased neuropeptide expression is observed in the spinal cord of AIA rats. To study the potential role of cytokines in the spinal cord of AIA, we wanted to determine whether there are changes of glial and cytokine expression (IL-1 beta, IL-6, TNF-alpha and IFN-gamma) in the spinal cord of AIA rats. Our data indicated that macroglia and MHC class II immunostaining were enhanced, astrocytes expressing GFAP were increased in number and immunostaining intensity. Using in situ hybridization and immunohistochemical methods, both mRNA and protein levels of IL-1 beta, IL-6 and TNF-alpha were significantly increased in the spinal cord of arthritic rats. Increased cytokine expression was presented in the reactive astrocytes and microglia.

Animals↗

PubMed2001

Comparing the similarity of time-series gene expression using signal processing metrics.

Many algorithms have been used to cluster genes measured by microarray across a time series. Instead of clustering, our goal was to compare all pairs of genes to determine whether there was evidence of a phase shift between them. We describe a technique where gene expression is treated as a discrete time-invariant signal, allowing the use of digital signal-processing tools, including power spectral density, coherence, and transfer gain and phase shift. We used these on a public RNA expression set of 2467 genes measured every 7 min for 119 min and found 18 putative associations. Two of these were known in the biomedical literature and may have been missed using correlation coefficients. Digital signal processing tools can be embedded and enhance existing clustering algorithms.

Algorithms↗

PubMed2001

[Molecular cloning and expression in E. coli of the surface-exposed lipoprotein LipL41 gene of Leptospira lai].

OBJECTIVE: To construct a recombinant expressive plasmid using LipL41 gene of leptospira lai for further research of subunit vaccine of leptospira. METHODS: A pair of oligonucleotide primers were designed based on the sequence of LipL41 of leptospira kirschneri RM 52 in Genbank. With genomic DNA of leptospira lai 017 as template, a fragment was amplified by PCR and DNA sequencing analysis showed this fragment to be the gene that encodes LipL41. A recombinant vector was constructed using plasmid pGEX1 lambda T and the expression of LipL41 gene was tested. RESULTS: The production of PCR was LipL41 gene. The recombinant plasmid was constructed and testified by nuclease digestion and PCR, and LipL41 gene could express in E. coli. CONCLUSION: The recombinant plasmid has been constructed successfully and LipL41 gene can express stably at high level.

Bacterial Outer Membrane Proteins↗

PubMed2001

[DNA sequence analysis and expression of the recombinant plasmid pBX1 from Borrelia burgdorferi B31 strain].

OBJECTIVE: This study was to provide the target antigen for the development of a Lyme disease vaccine and serodiagnosis reagent. METHODS: We used the automatic DNA sequencing machine (Model 377) to detect the nucleotide sequence of the inserted part of the recombinant plasmid pBX1 from Borrelia burgdorferi B31 strain. The restriction enzyme map of the inserted part of pBX1 was analysed by using computer software. The expressed product of pBX1 in E. coli XLI-Blue MRF was analysed by using SDS-PAGE and western-blotting. RESULTS: 1. DNA sequencing showed that pBX1 contained a 477bp inserted gene fragment, and when it was compared with the published sequence of the specific region of the gene of the 83 kd antigen protein from Borrelia burgdorferi B31 strain, only one amino acid codon was different. 2. The restriction enzyme map of the inserted part of pBX1 was successfully constructed. 3. The recombinant plasmid pBX1 expressed a 29 kd fusion protein in E. coli XL1-Blue MRF' after induced with IPTG. The recombinant fusion protein could be recongnized by rabbit polyclonal antiserum against Borrelia burgdorferi B31 strain. CONCLUSION: A recombinant plasmid which contains the gene fragment encoding the specific region of the 83 kd antigen protein from Borrelia burgdorferi B31 strain has been successfully constructed. The recombinant plasmid can stably express 29 kd fusion protein in E. coli XL1-Blue MRF'. These results could serve as a base of further studies on the usefulness of the fusion protein in serodiagnosis and vaccine for Lyme disease.

Animals↗

PubMed2000

Molecular cloning and structural characterization of the rat thymosin beta15 gene.

Thymosin beta15 is expressed in metastatic variants of Dunning rat prostatic carcinoma but not in a nonmetastatic variant. It is also upregulated in malignant human prostate cancers and was shown to be a predictive marker for patient outcome in prostate cancer. To explore the molecular mechanism of transcriptional regulation of thymosin beta15, we isolated and characterized the rat thymosin beta15 gene. The gene appears to exist as a single copy in the rat genome and to comprise three exons distributed over 2kb. The transcription start site was defined by primer extension analysis at 30 bp upstream of the translation start site. Sequence analysis of the 5'-flanking region of the transcription start site revealed properties consistent with promoter activity. The promoter region is GC rich and contains numerous consensus transcription factor binding sites as well as a GC box, but no TATA box. The transcriptional activity of the 5'-flanking region was analyzed by transient transfection of rat prostate cancer cells with firefly luciferase-encoding gene expression vector constructs. The isolated 5' region showed significant promoter activity. The identification of the thymosin beta15 promoter could aid our understanding of the regulation of this gene and its enhanced expression in human cancer.

Animals↗

PubMed2000

Investigation of the distribution and changes of VLDLR subtype in fibrotic cardiac muscles.

Very low-density lipoprotein receptor (VLDLR) is the major receptor with which cells can uptake the triacylglycerol from blood. It is divided into two subtypes according to presence of O-linked sugar domain located in the VLDLR receptor immediately outside of the membrane. Type I VLDLR contains the O-link domain, while type II has no such domain. The type I VLDLR are mainly found on the surface of human myocardial cells. The result of our quantitative polymerase chain reaction on the normal and fibrotic cardiac muscles showed that both subtypes and expression level of VLDLR on the myocardial cell surface did not vary significantly between the normal and the fibrotic cardiac muscles despite the presence of malfunction due to fibrosis. This finding suggests that fibrosis doesn't exert significant influence on the subtype and the expression of VLDLR on the surface of myocardial cells. Such inconsistence with the changes found in other fibrotic tissues is awaiting further studies.

Fibrosis↗

PubMed2000

Double cell bulk acoustic wave sensor for ion chromatographic study of the relation between magnesium and growth of organisms.

An ion chromatography (IC) method with a double cell bulk acoustic wave (DCBAW) detector was used for the detection of magnesium concentration decrease during the culture of whole cells. The detector parameters were optimized according to its theoretical equation, including the cell constants and the background conductance of the adjusting cell. A low temperature coefficient and thus high sensitivity were obtained by this method. The detection limit is 0.01 ppm, and the linear range is 0.05-50 ppm. A new mathematical model was developed to describe the growth of the cell. The baseline for this model is the concept that a noninteractive growth process occurs among perfectly substitutable nutrients if the locus of points of the substrate concentrations producing equal growth rate is linear. The monitoring results agreed well with the calculated results.

Acoustics↗

PubMed2000

[Amplification and sequence of human CD14 gene from human mononuclear cell in peripheral blood].

OBJECTIVE: To introduce a new method for getting human CD14 gene. METHODS: Based on the character of CD14 gene, the authors amplified the CD14 gene directly from genome DNA of human mononuclear cell in peripheral blood by PCR for the first time. RESULTS: A human CD14 gene about 1.1 kb was successfully amplified from genome DNA of human mononuclear cell in peripheral blood, and the sequence analysis has indicated that the CD14 gene cloned in this way is the same as the sequence reported by other authors. CONCLUSION: It is a simple and effective method to obtain human CD14 gene from genome DNA of human mononuclear cell in peripheral blood.

Base Sequence↗

PubMed2000

[The MN typing of whole blood and bloodstains by the method of one-step sandwich ELISA].

The samples of whole blood and bloodstain were MN-typed by the method of one-step sandwich ELISA, monoclonal antibodies include anti-M, N and glycern-protein. The lowest sample amount in this study is: for whole blood is 0.065 microliter, for bloodstain about 10 to 50 ng. 455 cases of fresh blood and 200 cases of fresh bloodstain are correctly typed. For 58 cases of old bloodstains, the success rate is 96.6%.

Antibodies, Monoclonal↗

PubMed1999

A soluble transforming growth factor beta type III receptor suppresses tumorigenicity and metastasis of human breast cancer MDA-MB-231 cells.

Transforming growth factor beta (TGF-beta) can promote late stage tumor progression in a number of model systems. In the present study, we have examined whether expression of a truncated soluble extracellular domain of TGF-beta type III receptor (sRIII) in human breast cancer MDA-MB-231 cells can antagonize the tumor-promoting activity of TGF-beta by sequestering active TGF-beta isoforms that are produced by the cancer cells. The secretion of sRIII reduced the amount of active TGF-beta1 and TGF-beta2 in the conditioned medium. This led to a significant reduction of the growth-inhibitory activity of the medium conditioned by sRIII-expressing cells on the growth of mink lung epithelial CCL64 cells in comparison with the medium conditioned by the control cells. The tumor incidence and growth rate of all of the three sRIII-expressing clones studied were significantly lower than those of the control cells in athymic nude mice. Four of five control cell-inoculated mice showed spontaneous metastasis in the lung, whereas none of the sRIII-expressing cell-inoculated mice had any lung metastasis. Thus, our results suggest that the sRIII may be used to antagonize the tumor-promoting activity of TGF-beta.

Animals↗

PubMed1999

IS3 peptide-formed ion channels in rat skeletal muscle cell membranes.

A 22-mer peptide, identical to the primary sequence of domain I segment 3 (IS3) of rat brain sodium channel I, was synthesized. With the patch clamp cell-attached technique, single channel currents could be recorded from the patches of cultured rat myotube membranes when the patches were held at hyperpolarized potentials and the electrode solution contained NaCl and 1 microM IS3, indicating that IS3 incorporated into the membranes and formed ion channels. The single channel conductances of IS3 channels were distributed heterogeneously, but mainly in the range of 10-25 pS. There was a tendency that the mean open time and open probability of IS3 channels increased and the mean close time decreased with the increasing of hyperpolarized membrane potentials. IS3 channels are highly selective for Na+ and Li+ but not for Cl- and K+, similar to the authentic Na+ channels.

Amino Acid Sequence↗

PubMed1999

Glutaryl-CoA dehydrogenase deficiency presenting as 3-hydroxyglutaric aciduria.

Two siblings who were found to have deficiency of glutaryl-CoA dehydrogenase were identified by the presence of large amounts of 3-hydroxyglutaric acid in the urine. Patients with this disease, termed glutaric acidemia or glutaric acidemia Type I, usually present with large amounts of glutaric acid in the urine, and amounts of 3-hydroxyglutaric acid found are less. Patients were ataxic and dystonic. Intelligence was normal. 3-Hydroxyglutaric acid in the urine was quantified by organic acid analysis via gas chromatography mass spectrometry (GCMS) and by stable isotope-dilution (internal standard) GCMS. Glutaryl-CoA dehydrogenase activity in cultured fibroblasts was found to be 2% of the control level. The nature of the mutations was identified, and both patients were found to be compound heterozygotes for R227P, which changed an arginine to a proline, and E365K, which changed a glutamate to a lysine.

Amino Acid Metabolism, Inborn Errors↗

PubMed1999

The neuropeptide Y Y1 receptor is a somatic receptor on dorsal root ganglion neurons and a postsynaptic receptor on somatostatin dorsal horn neurons.

Using indirect immunofluorescence, neuropeptide Y Y1 receptor (Y1 receptor)-like immunoreactivity (LI) was localized close to the plasmalemma of small neurons in lumbar dorsal root ganglia (DRGs) and neurons in the inner lamina II of the lumbar spinal cord of the rat. Using confocal microscopy, colocalization of Y1 receptor-LI and transferrin receptor-LI, a marker for endosomes and coated vesicles, was observed in dot-like structures along the plasmalemma. Under the electron microscope, Y1 receptor-LI was localized in coated vesicles and endosomes, in the membrane of tubular cisternae, sometimes connected to multivesicular bodies, and in the plasmalemma. These complex distribution patterns may reflect receptor turnover and internalization processes. In the lamina II of the spinal dorsal horn, Y1 receptor-LI was localized in the plasmalemma of neurons without any apparent association with paramembrane structures, as described above for the DRG neurons. Many dendrites were Y1 receptor-positive, and some of them made synaptic contacts with unstained axonal terminals. In general, Y1 receptor-LI was localized in the membrane outside the postsynaptic density. Double-immunofluorescence staining showed that most Y1 receptor-immunoreactive neurons in lamina II contained somatostatin-LI. Both in DRG and dorsal horn neurons, the Y1 receptor thus seems to represent a postjunctional/postsynaptic receptor.

Animals↗

PubMed1999

An improved stereotactic technique for cyst cannulation.

Stereotactic techniques for cannulation of cystic structures, within the brain, are well known. Superimposed structures (vessels, ventricles, etc.) may make this problematic as does the need to approach the cystic structure perpendicular to its tangent plane (rather than "glancing") as with a craniopharyngioma cyst. To facilitate a three-dimensional visualization of the trajectory, we have employed digital holography. Transparent holographic images of cystic structures, ventricles, and sulci are rendered from T2-weighted MR data. Holographic images of vascular structures are rendered from CT or MR angiographic data. Vascular holograms are superimposed over the brain holograms, demonstrating the spatial relationships of these structures with regard to each other. Holographic images of the skull are rendered from CT slices. A Laitinen stereotactic frame (Sandstrom) is placed on the patient prior to obtaining the CT. The skull, pre-existing shunt catheters, and the stereotactic frame are all readily visible. The brain and vascular holograms are superimposed on these. The resulting image clearly demonstrates cystic structures, ventricles, vessels, pre-existing catheters, all within the skull and stereotactic frame. Using this holographic image as a "phantom", the actual Laitinen stereotactic frame is placed within its holographic image. The optical trajectory is then chosen, and the articulated arm of the stereotactic device is so adjusted. Subsequently, the frame is used to effect stereotactic placement of the cannula, in the usual manner. The major advantages of this technique are twofold. The first advantage lies with the fact that the surgeon can readily visualize the entire trajectory of the needle, and easily appreciate all structures which may be encountered by the needle on its passage from the skull to the target. Presumably, the surgeon's knowledge of anatomy would unable such knowledge to be apparent, but in complex cases the "safe" corridor may be rather small, and its limits may not be intuitively obvious. This is all the more the case, when obstacles along the pathway are pathologically distorted, or when they are not of tissue origin (shunt catheters, etc.). Employing this technique, we have successfully cannulated cystic structures in six patients, three of which presented with complex trajectory problems.

Brain Diseases↗