A novel TCD grading system for residual flow in stroke patients.
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Blood Flow Velocity↗
Biomedical subjects
M Ma
Publications and source records attributed to M Ma.
Transgenic mice with overexpression of human scavenger receptor A on endothelial cells.
OBJECTIVES: To establish a new transgenic mouse model for determining the function and role of human scavenger receptor A (SR-A) in atherosclerosis in vivo. METHODS: Human scavenger receptor minigene-driven mouse tie-1 promoter was constructed and confirmed by endonuclease digestion and sequence analysis. Transgenic mice were generated via the microinjection method. PCR and Southern blot were used to screen the positive transgenic mice. RT-PCR and immunohistochemical analysis were used to detect the level and location of human SR-AI expression in transgenic mice. The activity of human SR-AI was determined by morphologic observation of aortic endothelial cells of transgenic mice under transmission electron microscopy. RESULTS: The electrophoresis assay showed the expected 4 fragments of 0.9 kb, 1.1 kb, 1.2 kb and 4.2 kb in the Sma I digest and 2 fragments of 0.8 kb and 6.7 kb in Bgl II digest of plasmids pTie-1/hSR-A. The fragment sequence of tie-1 promoter and human SR-A cDNA in plasmids pTie-1/hSR-A was correct and no ATG before the translation initiation sites of human SR-A was found by sequence analysis. 561 injected and surviving embryos with the purified human SR-A minigene were implanted into the oviducts of 19 ICR pseudopregnant mice. Among the 54 surviving pups from 13 foster mothers, 7 were identified by PCR and Southern blot analysis. The results of RT-PCR and immunohistochemical analysis showed human SR-A was specifically expressed on vascular endothelial cells of the aorta and renal artery, as well as hepatic sinusoidal endothelial cells in transgenic mice. Transmission electron microscope (TEM) of aorta of transgenic mice showed that a large number of vesicles, multivesicle bodies and swollen mitochondria filled the plasma of endothelial cells. CONCLUSIONS: A transgenic mouse model with overexpression of human SR-A in endothelial cells was successfully established. The transgene was integrated and transmitted into the chromosome of transgenic mice. Tie-1 promoter controlled the transgene to express in endothelial cells in mice. Pinocytic activity of aortic endothelial cells in transgenic mice was higher than that of C57BL/6J mice. Our studies will provide a new transgenic model for investigation of atherosclerosis and functions of human SR-A.
Animals↗
[Mutagenic activity of organic pollutants extracted from waters in Guanting Reservoir and Yongding River].
Water samples collected from Guanting Reservoir and Yongding River in July 1999 were examined by Ames test to evaluate the mutagenic activity of organic pollutants. The samples have been concentrated by using XAD-2 resin filled columns. In the test with strain TA98, direct mutagenic effects (-S9) were observed in water extracted from Bridge No.8 and Yanchi at the dosage of 0.8 L/plate, indicating the existence of direct frame shift mutagens. The mutagenic effects disappeared after addition of S9, indicating no pro-mutagen in the samples. In the test with strain TA100, direct base pair substitute mutagenic effect was observed only in the sample from Bridge No. 8 at the dosage of 0.4 L/plate. When adding S9, suspicious positive reaction could exist at the dosage of 0.8 L/plate. The results demonstrated that the water in Yongding River has been heavily polluted by mutagens, for which further studies should be carried out to identify the sources and types of these mutagens.
Animals↗
[Cloning and sequence analysis of the phytase phyA gene of Aspergillus niger N25].
The phyA encoding phytase of Aspergillus niger N25 was amplified by the polymerase chain reaction (PCR) with primers designed according to the sequences of the phyA in GenBank. The amplified fragment was cloned and sequenced. The results show that: the coding region is 1506 bp in size, includes a 102 bp intron, and encodes a peptide of 476 amino acid residues, in which there is a signal peptide with 19 amino acids and a mature peptide of 448 amino acids. Comparison of this sequence with the phyA of the natural A. niger NRRL3135 (GenBank Accession: M94550), the most highly secreting-phytase strain, shows that the nucleotide homology is as high as 96.746%, and the amino acid homology comes up to 97.64%. The phyA of A. niger N25 strain in this paper is appropriate to be used to construct the phytase gene-engineering bacteria.
6-Phytase↗
Functional mosaic organization of mouse olfactory receptor neurons.
In contrast to rapid progress in the molecular biology of olfaction, there are few physiological data to characterize the odor response properties of different populations of olfactory receptor neurons (ORNs) and their spatial distributions across the epithelium, which is essential for understanding the coding mechanisms underlying odor discrimination and recognition. We have tested the hypothesis that the ORNs are arranged in a functional mosaic, using an intact epithelial preparation from the mouse, in which odor responses of many ORNs in situ can be monitored simultaneously with calcium imaging techniques. ORNs responding to a given odor were widely distributed across epithelium and intermingled with ORNs responding to other odors. Tight clusters of ORNs responding to the same odor were observed. For a given odor, more ORNs were recruited when the concentration was increased. ORNs were able to distinguish between pairs of enantiomers by showing distinct but somewhat overlapping patterns. The results provide evidence regarding the response spectra of ORNs in situ, supporting the combinatorial coding of odor quality and intensity by different ORN subsets.
Animals↗
Speciation of key arsenic metabolic intermediates in human urine.
Biomethylation is the major human metabolic pathway for inorganic arsenic, and the speciation of arsenic metabolites is essential to a better understanding of arsenic metabolism and health effects. Here we describe a technique for the speciation of arsenic in human urine and demonstrate its application to the discovery of key arsenic metabolic intermediates, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), in human urine. The study provides a direct evidence in support of the proposed arsenic methylation pathway in the human. The finding of MMAIII and DMAIII in human urine, along with recent studies showing the high toxicity of these arsenicals, suggests that the usual belief of arsenic detoxification by methylation needs to be reconsidered. The arsenic speciation technique is based on ion pair chromatographic separation of arsenic species on a 3-micron particle size column at 50 degrees C followed by hydride generation atomic fluorescence detection. Speciation of MMAIII, DMAIII, arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) in urine samples is complete in 6 min with detection limits of 0.5-2 micrograms/L. There is no need for any sample pretreatment. The capability of rapid analysis of trace levels of arsenic species, which resulted in the findings of the key metabolic intermediates, makes the technique useful for routine arsenic speciation analysis required for toxicological and epidemiological studies.
Arsenic↗
Orbitally degenerate spin-1 model for insulating V2O3
Motivated by recent neutron, x-ray absorption, and resonant scattering experiments, we revisit the electronic structure of V2O3. We propose a model in which S = 1 V3+ ions are coupled in the vertical V-V pairs forming twofold orbitally degenerate configurations with S = 2. Ferro-orbital ordering of the V-V pairs gives a description which is consistent with all experiments in the antiferromagnetic insulating phase.
Journal Article↗
DMPS-arsenic challenge test. II. Modulation of arsenic species, including monomethylarsonous acid (MMA(III)), excreted in human urine.
The administration of sodium 2,3-dimercapto-1-propane sulfonate (DMPS) to humans chronically exposed to inorganic arsenic in their drinking water resulted in the increased urinary excretion of arsenic, the appearance and identification of monomethylarsonous acid (MMA(III)) in their urine, and a large decrease in the concentration and percentage of urinary dimethylarsinic acid (DMA). This is the first time that MMA(III) has been detected in the urine. In vitro biochemical experiments were then designed and performed to understand the urinary appearance of MMA(III) and decrease of DMA. The DMPS-MMA(III) complex was not active as a substrate for the MMA(III) methyltransferase. The experimental results support the hypothesis that DMPS competes with endogenous ligands for MMA(III), forming a DMPS-MMA complex that is readily excreted in the urine and points out the need for studying the biochemical toxicology of MMA(III). It should be emphasized that MMA(III) was excreted in the urine only after DMPS administration. The results of these studies raise many questions about the potential central role of MMA(III) in the toxicity of inorganic arsenic and to the potential involvement of MMA(III) in the little-understood etiology of hyperkeratosis, hyperpigmentation, and cancer that can result from chronic inorganic arsenic exposure.
Adult↗
Effects of Manduca diuresin on neonates of the tobacco hornworm, Manduca sexta.
Manduca diuresin (MD), a 30 amino acid peptide, was isolated and identified from the type IIb median neurosecretory cells in the brain of adult Manduca sexta (Blackburn et al., Biochem. Biophys. Res. Commun., 181, 927-932, 1991). The synthetic hormone stimulates water loss in the adult moth both in vitro using isolated Malphigian tubule preparations and in vivo using decapitated adult moths as bioassay animals (Blackburn and Ma, Arch. Insect Biochem. Physiol., 27, 3-10, 1994). In the present study, MD was shown to have adverse physiological effects on neonates of Manduca sexta when fed synthetic hormone-treated leaf discs. With a sustained diet of MD-treated discs, neonates exhibited symptoms of reduced food consumption and marginal weight increases. In addition to slowed growth and reduced developmental rates, a high percentage of these neonates failed to molt into second instar larvae and death usually followed shortly thereafter. This is a first report that a synthetic insect neuropeptide has shown detrimental effect on insect larvae by ingestion. The possibility of utilizing this peptide in plant protection is discussed.
Animals↗
Occurrence of monomethylarsonous acid in urine of humans exposed to inorganic arsenic.
Monomethylarsonous acid (MMA(III)) has been detected for the first time in the urine of some humans exposed to inorganic arsenic in their drinking water. Our experiments have dealt with subjects in Romania who have been exposed to 2.8, 29, 84, or 161 microg of As/L in their drinking water. In the latter two groups, MMA(III) was 11 and 7% of the urinary arsenic while the monomethylarsonic acid (MMA(V)) was 14 and 13%, respectively. Of our 58 subjects, 17% had MMA(III) in their urine. MMA(III) was not found in urine of any members of the group with the lowest level of As exposure. If the lowest-level As exposure group is excluded, 23% of our subjects had MMA(III) in their urine. Our results indicate that (a) future studies concerning urinary arsenic profiles of arsenic-exposed humans must determine MMA(III) concentrations, (b) previous studies of urinary profiles dealing with humans exposed to arsenic need to be re-examined and re-evaluated, and (c) since MMA(III) is more toxic than inorganic arsenite, a re-examination is needed of the two hypotheses which hold that methylation is a detoxication process for inorganic arsenite and that inorganic arsenite is the major cause of the toxicity and carcinogenicity of inorganic arsenic.
Adolescent↗
Intracellular mRNA cleavage induced through activation of RNase P by nuclease-resistant external guide sequences.
Most antisense oligonucleotide experiments are performed with molecules containing RNase H-competent backbones. However, RNase H may cleave nontargeted mRNAs bound to only partially complementary oligonucleotides. Decreasing such "irrelevant cleavage" would be of critical importance to the ability of the antisense biotechnology to provide accurate assessment of gene function. RNase P is a ubiquitous endogenous cellular ribozyme whose function is to cleave the 5' terminus of precursor tRNAs to generate the mature tRNA. To recruit RNase P, complementary oligonucleotides called external guide sequences (EGS), which mimic structural features of precursor tRNA, were incorporated into an antisense 2'-O-methyl oligoribonucleotide targeted to the 3' region of the PKC-alpha mRNA. In T24 human bladder carcinoma cells, these EGSs, but not control sequences, were highly effective in downregulating PKC-alpha protein and mRNA expression. Furthermore, the downregulation is dependent on the presence of, and base sequence in, the T-loop. Similar observations were made with an EGS targeted to the bcl-xL mRNA.
3' Untranslated Regions↗
Methodological issues in the use of guidelines and audit to improve clinical effectiveness in breast cancer in one United Kingdom health region.
AIMS: To develop a system to improve and monitor clinical performance in the management of breast cancer patients in one United Kingdom health region. DESIGN: An observational study of the changes brought about by the introduction of new structures to influence clinical practice and monitor change. SETTING: North Thames (East) Health region, comprising seven purchasing health authorities and 21 acute hospitals treating breast cancer. SUBJECTS: The multi-disciplinary breast teams in 21 hospitals and an audit sample of 419 (28%) of the breast cancer patients diagnosed in 1992 in the region. INTERVENTIONS: Evidence-based interventions for changing clinical practice: regional guidelines, senior clinicians acting as < >, audit of quality rather than cost of services, ownership of data by clinicians, confidential feed-back to participants and education. OUTCOME MEASURES: Qualitative measures of organizational and behavioural change. Quantitative measures of clinical outcomes compared to guideline targets and to results from previous studies within this population. RESULTS: Organizational changes included the involvement, participation of and feedback to 16 specialist surgeons and their multidisciplinary teams in 21 hospitals. Regional clinical guidelines were developed in 6 months and the dataset piloted within 9 months. The audit cycle was completed within 2 years. The pilot study led to prospective audit at the end of 2 years for all breast cancers in the region and a 15-fold increase in high quality clinical information for these patients. Changes in clinical practice between 1990 and 1992 were observed in the use of chemotherapy (up from 17-23%) and axillary surgery (up from 46-76%). CONCLUSIONS: The approach used facilitated rapid change and found a balance between local involvement (essential for sustainability within a hospital setting) and regional standardization (essential for comparability across hospitals). The principles of the approach are generalized to other cancers and to other parts of the UK and abroad.
Breast Neoplasms↗
Carvedilol enhances atrial and brain natriuretic peptide mRNA expression and release in rat heart.
To clarify the role of the natriuretic peptide (NP) system in the myocardial protective effects of carvedilol, a beta-blocking agent, we investigated the effects of carvedilol on the NP system in the rat heart. After oral administration of carvedilol (low-dose group: 2 mg/kg/day, group C2; high-dose group: 20 mg/kg/day, group C20) for 1 week, plasma rat atrial NP (r-ANP), atrial mRNA levels of ANP, left ventricular mRNA of brain NP (BNP), NP receptor-A and NP receptor-C (NPR-C) (as a clearance receptor) were measured. Values were compared with those in vehicle-treatment rats (group V). The concentration of r-ANP was significantly higher in group C2 (135 +/- 9 pg/ml) and group C20 (161 +/- 11 pg/ml) than group V (75 +/- 6 pg/ml; both p < 0.01). ANP and BNP mRNA levels were significantly increased and NPR-C was significantly down regulated in group C2 (151 +/- 7, 120 +/- 8 and 78 +/- 7%, respectively, vs. group V) and group C20 (164 +/- 8. 133 +/- 7 and 72 +/- 8%, respectively, vs. group V) compared with group V (all p < 0.01). These results suggest that not only a high dose, but a low dose of carvedilol has the effect of increasing plasma ANP and BNP levels. This effect was closely related to the upregulation of ANP and BNP mRNA expression, and the down regulation of NPR-C mRNA expression in the heart. These mechanisms seem to account for a sizable portion of the protective effect of carvedilol for heart diseases.
Adrenergic beta-Antagonists↗
Determination of monomethylarsonous acid, a key arsenic methylation intermediate, in human urine.
In this study we report on the finding of monomethylarsonous acid [MMA(III)] in human urine. This newly identified arsenic species is a key intermediate in the metabolic pathway of arsenic biomethylation, which involves stepwise reduction of pentavalent to trivalent arsenic species followed by oxidative addition of a methyl group. Arsenic speciation was carried out using ion-pair chromatographic separation of arsenic compounds with hydride generation atomic fluorescence spectrometry detection. Speciation of the inorganic arsenite [As(III)], inorganic arsenate [As(V)], monomethylarsonic acid [MMA(V)], dimethylarsinic acid [DMA(V)], and MMA(III) in a urine sample was complete in 5 min. Urine samples collected from humans before and after a single oral administration of 300 mg sodium 2,3-dimercapto-1-propane sulfonate (DMPS) were analyzed for arsenic species. MMA(III) was found in 51 out of 123 urine samples collected from 41 people in inner Mongolia 0-6 hr after the administration of DMPS. MMA(III )in urine samples did not arise from the reduction of MMA(V) by DMPS. DMPS probably assisted the release of MMA(III) that was formed in the body. Along with the presence of MMA(III), there was an increase in the relative concentration of MMA(V) and a decrease in DMA(V) in the urine samples collected after the DMPS ingestion.
Arsenic↗
Adenoviral-mediated gene transfer of ICP47 inhibits major histocompatibility complex class I expression on vascular cells in vitro.
PURPOSE: Many viruses have evolved mechanisms to evade detection by the host immune system. The herpes simplex gene ICP47 encodes a protein that binds to the host antigen-processing transporter, inhibiting the formation of major histocompatibility complex class I (MHC-I) antigens in infected cells. MHC-I antigen expression is also important in acute allograft rejection. This study was designed to quantitate the effect of adenoviral-mediated gene transfer of ICP47 on MHC-I cell surface expression of human vascular cells. We hypothesized that the transduction of vascular cells with a replication-incompetent adenoviral vector that was expressing ICP47 (AdICP47) would inhibit constitutive and inducible MHC-I expression and thereby reduce the rate of cytolysis of ICP47-transduced vascular cells by sensitized cytotoxic T lymphocytes (CTL). METHODS: A replication-incompetent adenoviral vector, AdICP47, was created to express ICP47 driven by the cytomegalovirus immediate early promoter. Cultured human vascular endothelial and smooth muscle cells and human dermal fibroblasts were transduced with either AdICP47 or the control empty vector AddlE1. Cell surface constitutive and gamma-interferon-induced MHC-I expression were quantitated by flow cytometry. A standard 4-hour chromium release cytotoxicity assay was used to determine the percent cytolysis of transduced and nontransduced endothelial cells by sensitized CTL. Finally, to quantitate the specificity of the effect of ICP47 on MHC-I expression, adhesion molecule expression was quantitated in both transduced and nontransduced cells. RESULTS: Constitutive MHC-I expression in AdICP47-transduced endothelial cells was inhibited by a mean of 84% +/- 5% (SEM) in five experiments. After 48 hours of exposure to gamma-interferon, AdICP47-transduced cells exhibited a mean of 66% +/- 8% lower MHC-I expression than nontransduced cells. Similar inhibition in MHC-I expression was achieved in AdICP47-transduced vascular smooth muscle cells and dermal fibroblasts. Percent cytolysis of AdICP47-transduced endothelial cells by CTL was reduced by 72%. Finally, the specificity of the effect of transduction of ICP47 on vascular cell MHC-I expression was confirmed by a lack of significant change in either constitutive or tumor necrosis factor-induced vascular cell adhesion molecule/intercellular adhesion molecule expression. CONCLUSION: Transduction of vascular cells with AdICP47 strongly inhibits both constitutive and inducible MHC-I expression in human vascular cells. AdICP47-transduced cells exhibited a substantial reduction in cytolysis by CTL. Thus AdICP47 transduction holds promise as a technique to characterize the role of MHC-I expression in acute vascular allograft rejection in vivo and as a potential therapeutic intervention.
Adenoviridae↗
[Construction of B. thuringiensis shuttle vector and expression of the cry1C gene].
We have constructed the E. coli-Bt shuttle vector pHV-1 by cloning the replicon (approximately 1.6 kb) of Bt ken-Ag and the aphI gene of pUC4K into pUC19. The rate of plasmid maintenance is more than 80% after 100 generations in E. coli, whereas 80% after 40 generations in Bti 4Q8. We have also constructed pHV-cry1C through cloning the alpha-amylase promoter from B. licheniformis and the cry1C gene from Bt 9510 into pHV-1 and introduced it into Bti 4Q8 by means of electroporation. Under the microscope, we can see that there is no crystal in Bti 4Q8, however, there are many rhomboid crystals in Bti 4Q8 (pHV-cry1C), which are smaller than those of Bt 9510. The bioassay result of Bti 4Q8 (pHV-cry1C) demonstrates that the expressed crystal protein is insecticidally active against Spodoptera exigue.
Animals↗
[Analysis of lymphocytic clone formation after stem cell transplantation and immunological reconstitution by gene fingerprinting].
OBJECTIVE: To analyze T lymphocytic clone formation in patients with malignant disease after bone marrow or peripheral blood stem cell transplantation and to understand the relationship between immunological reconstitution and clinic remission. METHODS: Due to the different TCRgamma gene rearrangements in different gamma/delta T cell clones, a gene fingerprinting was set up by PCR and denatured gel electrophoresis. The gene fingerprinting was used to analyze the gamma-delta T cell clone variations in 8 patients who received stem transplantation. In order to identify the source of the regenerated lymphocytes, the polymorphism of microsatellite was used at mean time. RESULTS: After PCR amplification and electrophoresis of each TCRgammaV region gene on a 60 cm sequence gel, a gene fingerprinting composed of about a hundred bands was set up. It showed the basic distribution of the dominant gamma/delta T cell clones in the body. Usually, a new band presenting after transplantation represented an expansive lymphocytic clone. Successful immunological reconstitution led to a good prognosis; and unsuccessful immunological reconstitution led to bad prognosis. After transplantation, some T cell clones expanded. Comparing the sequences of a expansive T cell clone in a multiple myeloma patient after auto-stem cell transplantation with 230 000 genes of immunoglobulin and T cell receptor in GeneBank, we found that two T cell line had homogenous sequences. Both T cell clones recognized homogeneous antigen. CONCLUSION: A new method to observe the distribution of gamma/delta T cells called gene fingerprinting was set up. Gene fingerprinting is useful in the analysis of immunological reconstitution after stem cells transplantation. The effect of transplantation is correlated to immunological reconstitution. Transplantation patients may appear some expansive T cell clones; probably they have anti - tumor effect.
Adult↗
[An ultrastructural observation on rat retina after photoreceptor cell implantation].
OBJECTIVE: To further study the retinal neuronal signal. METHODS: The Wistar/RCS (RCS rats are rats with hereditary photoreceptor degeneration) rats were respectively as donors/acceptors, and the retinal pathway was reconstructed with the technique of pure photoreceptor transplantation. The photoreceptor layer of the retina was obtained with the technique of retinal whittle by manual method or excimer laser. The specimens were got separately at 2 weeks and 1 month after the transplantation and studied under the light and transmission electron microscopes. RESULTS: Most transplanted photoreceptors with physical poles were lined up regularly between the retinal pigment epithelium (RPE) and inner nuclear layer. It was shown that in the new outer plexiform layer the relatively integral synapse and its interconnection were seen. CONCLUSION: The retinal neuronal pathway can be reconstructed by retinal transplantation.
Animals↗