Biomedical subjects
Publications and source records attributed to D Ma.
AcrD, a transporter belonging to the resistance-nodulation-division family, was shown to participate in the efflux of aminoglycosides. Deletion of the acrD gene decreased the MICs of amikacin, gentamicin, neomycin, kanamycin, and tobramycin by a factor of two to eight, and DeltaacrD cells accumulated higher levels of [(3)H]dihydrostreptomycin and [(3)H]gentamicin than did the parent strain.
Optically inactive 1-[3-cyclohexen-1-ylcarbonyl] piperidine and 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine are repellents against blood-feeding arthropods. Pure stereoisomers of these compounds were synthesized and characterized for use in bioassays. Initial laboratory tests with the malaria vector Anopheles stephensi Liston showed that this species was repelled differentially by the stereoisomers of 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine. Two stereoisomers were twice as repellent as the other stereoisomers. These results indicate that stereoisomerism influences repellent efficacy in this class of compounds.
Hyperthermic isolated limb perfusion (ILP) effectively treats locally recurrent metastatic disease in malignant melanoma of the extremities. The goal of ILP is to decrease the rate of further recurrent disease and eradicate tumor load to achieve wound hygiene and preservation of limb function. This article reviews the development over the last 45 years of ILP in the treatment of malignant melanoma, describes the surgical technique of ILP, and reviews the results of clinical trials with various chemotherapeutic agents. It discusses the recent addition of tumor necrosis factor alpha to the list of drugs currently being explored in hyperthermic ILP, in the ongoing attempt to improve the treatment for recurrent malignant melanoma of the extremities.
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OBJECTIVE: To establish a method for the detection of TT virus (TTV) DNA by polymerase chain reaction (PCR)-microplate hybridization and to find out various influential factors of the assay. METHODS: TTV DNA extracted by guanidinium thiocyanate was amplified by PCR, the PCR primers were pre-labeled with biotin. By conjugation of biotin with streptavidin, the amplified products were coated to the microplate well, and hybridized with FITC- probe simultaneously. After being reacted with Anti-Fluorescein POD, the products that contained FITC probe were coloured by TMB-H2O2 and then measured the optical density using a microplate reader at 450 nm wavelength. RESULTS: The optimal concentration of NaOH was 0.3 mol/L, and the optimal time of hybridization and enzymatic reaction was 60 minutes and 45 minutes, respectively. The results also showed that the positive rate of TTV infection in normal population, hepatitis A-G and hepatitis non A-G was 13.6%, 20.3% and 28.1%, respectively. CONCLUSIONS: Comparing the PCR-microplate hybridization with the electrophoresis assay, the former is simple, rapid, sensitive and specific and is expected to be a new technique instead of electrophoresis assay as a routine method for TTV DNA detection.
OBJECTIVE: To study factors influencing survival rate of adenoid cystic carcinoma (ACC) of the salivary glands. METHODS: One hundred and twelve cases were followed up for move than ten years and were studied to investigate factors influencing the survival rate of patients. Statistical analysis was performed using a computer program (Survcalc, John Wiley Co.). The data were statistically treated for survival curves according to the kaplan-meier method. The log rank tests were employed to assess the statistical significance of various groups. RESULTS: The age of the patients younger than 50 years old, early clinical stage, glandular/tubular histological type and tumor without nerve involvement had the best prognosis. Age of the patients older than 50 years old, ACC in the submandibular gland, advanced clinical stage (stage III and IV), solid histological type and tumor with nerve involvement had a poor prognosis. CONCLUSIONS: Age of the patients, tumour site, clinical stage, histological type and with or without nerve involvement are the important factors influencing the prognosis.
Algorithm of bidirectional associative memory (BAM) is depicted. BAM sum up all sample pattern with different weighting factor to recall the true pattern. The ability to recall pattern correctly is determined by how the sample pattern are weighted. Selecting the maximum of weighting factors by competition can get best performance of BAM in presence of noise.
OBJECTIVE: To obtain mouse anti-human TFAR19 monoclonal antibodies for further study of the structure and function of the apoptosis-related protein TFAR19. METHODS: BALB/c mice were immunized with recombinant human TFAR19, hybridoma cells were screened by cell fusion and subcloning approach. The monoclonal antibodies were identified by ELISA and Western blotting. RESULTS: Three hybridoma cells (C1, C10, 2C12) stable in secreting anti-TFAR19 monoclonal antibodies were obtained. The monoclonal antibodies showed high specificity and high titer to TFAR19 with various affinity. All of them belong to IgG1 subclass. CONCLUSIONS: These monoclonal antibodies could bind specifically to TFAR19 protein.
OBJECTIVE: To investigate the mechanisms resulting in cardiovascular diseases and birth defect. METHODS: Induced screening and differential display, Northern blot, and immunohistochemistry assay were applied to clone the homocysteine-induced gene HCY-2 and detect the expression of HCY-2 gene respectively. RESULTS: A novel HCY-induced full length cDNA--HCY-2 which encodes 142 amino acids was obtained from vascular smooth muscle cells of rats. Results of the Northern blot and immunohistochemistry assays suggest that it widely expresses in many kinds of tissues such as heart, kidney, brain, liver, and lung. In vitro, we transferred recombinant HCY-2 gene into endothelial cells and found that it could induce apoptosis and DNA injury. In vivo, HCY-2 gene could induce chicken embryo cells apoptosis and embryo malformation. CONCLUSIONS: The results indicated that HCY-2 gene might be a novel apoptosis-inducing gene and might be involved in the pathogenesis of cardiovascular diseases and birth defects induced by hyperhomocysteinemia.
In this work, the stability of 13 kinds derivative of thiourea were studied by the UV absorption spectra and IR spectra of thiourea compounds in acidic medium at pH = 4.00, neutrality medium at pH = 7.00, basic property medium at pH = 10.00, under the influence of diffeveut store time, oxygen and sun light. Their structures were discussed and the changing rules of stability were developed.
The measurement of N-acetylaspartic acid (NAA), N-acetylglutamic acid (NAG), and N-acetylaspartylglutamic acid (NAAG) in the whole brain of 3-mercaptopropionic acid (3-MPA)-treated rats has been developed using liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface system. The recoveries of these compounds were 90.85 +/- 3.43% for NAA, 91.62 +/- 5.47% for NAG, and 92.29 +/- 4.44% for NAAG. The detection limits for NAA, NAG, and NAAG were 12, 15, and 20 microg/ml, respectively. After administration of 3-MPA, the concentrations of NAA, NAG, and NAAG in the whole brain over 10 min increased 177.25, 134.23, and 127.70%, respectively. These concentrations then decreased over the next 60 min. The simultaneous determination of NAA, NAG, and NAAG using this method was found to be very useful for studies of metabolism of NAA, NAG, and NAAG in biological samples.
Benzolactam-V7 (3a), a simplified analogues of (-)-indolactam-V with twist-form conformation, was synthesized and evaluated as a new protein kinase C modulator. Both 3a and its-7-substituted analogue 3c showed weak binding activity to displace PDBU binding from recombinant PKCalpha.
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Transgenic mice expressing human light neurofilament protein (NF-L) display early perikaryal accumulations of disarrayed neurofilaments in layers II/III of the parietal cortex and in the ventrobasal complex of thalamus. This cytoskeletal abnormality, reflected by strong NF-L immunoreactivity, is transient in the developing cortex but persists until old age in the thalamus. To investigate whether it leads to neuronal death, the unbiased cell counting method of the dissector was applied to the parietal cortex and the thalamus of normal and transgenic mice at various postnatal (P10, P20, P90) and advanced ages (14-18 months). Similar data were also obtained from the primary visual cortex free of NF-L accumulation. Compared with normal, the total number of neurons in the parietal (but not occipital) cortex of transgenic mice showed little change during the postnatal period, but decreased markedly with old age, particularly in layers II/III. Severe neuronal loss was also documented in the thalamic ventrobasal complex of aged transgenic mice. The delayed neuronal death in the parietal cortex, occurring long after recovery from the NF-L accumulations, was suggestive of a combination of deleterious factors, including the early overproduction of neurofilament protein and subsequent loss of afferent input from the affected somatosensory thalamic nuclei. Furthermore, strong accumulation of lipofuscin in the neurons of aged transgenic mice suggested that oxidative stress partakes in the mechanisms through which NF-L overproduction compromises neuronal viability.
The measurement of gamma-aminobutyric acid (GABA) and glutamic acid (Glu) in the whole brain and in various regions of the brain in 3-mercaptopropionic acid (3-MPA)-treated rats has been developed using liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface system. The recoveries of these compounds were 94.90+/-4.18% for GABA, 95.60+/-2.86% for Glu after ion-exchange treatment. The detection limits for GABA and Glu were 2.5+/-0.3 microg/ml and 5.0+/-0.8 microg/ml, respectively, when 20 microl sample were injected. GABA concentration in the whole brain decreased gradually to 5 min and reached 63% of normal value after administration of 3-MPA, and the concentration increased gradually thereafter until 60 min. Conversely, the concentration of Glu in the whole brain increased gradually to 10 min and reached 154% of normal value, and after that decreased gradually and reached almost normal level at 60 min after administration of 3-MPA. GABA concentration in various regions of brain decreased to 5 min in all regions after administration of 3-MPA, and reached normal levels at 60 min as in the whole brain. This method was found to be useful for studies of metabolism of GABA and Glu in biological samples.
Activation of protein kinase C is known to favor the alpha-secretase processing of the Alzheimer's disease (AD) amyloid precursor protein (APP), resulting in the generation of non-amyloidogenic soluble APP (sAPP). Consequently, the relative secretion of amyloidogenic Abeta1-40 and Abeta1-42(3) is reduced. This is particularly relevant since fibroblasts and other cells expressing APP and presenilin AD mutations secrete increased amounts of total Abeta and/or increased ratios of Abeta1-42(3)/Abeta1-40. Interestingly, PKC defects have been found in AD brain alpha and beta isoforms) and in fibroblasts (alpha isoform) from AD patients. Here, we use a novel PKC activator (benzolactam, BL) with improved selectivity for the alpha, beta and gamma isoforms to enhance sAPP secretion in fibroblasts from AD patients and in PC12 cells. Incubation (2 h) of AD fibroblasts with BL (1 and 10 microM) resulted in significant increases of sAPP secretion over basal levels. sAPP secretion in BL-treated AD cells was also slightly higher compared to control BL-treated fibroblasts, which only showed significant increases of sAPP secretion after treatment with 10 microM BL. Staurosporine (a PKC inhibitor) eliminated the effects of BL in both control and AD fibroblasts. BL and a related compound (LQ12) also caused an approximately 3-fold sAPP secretion in PC12 cells. The use of a novel and possibly non-tumorigenic PKC activator may prove useful to favor non-amyloidogenic APP processing and is, therefore, of potential therapeutic value.
Microtubule-associated protein 1B (MAP1B) is expressed at high levels during development of the nervous system and is localized primarily in neurons while specific phosphorylated isoforms of MAP1B are localized exclusively in growing axons. The levels of MAP1B are down regulated in most regions of the adult CNS, but remain high in neurons and axons of the PNS. This study demonstrates that the expression of MAP1B is induced in adult Schwann cells following sciatic nerve lesion and regeneration. High levels of both mRNA and the MAP1B protein were detected in Schwann cells associated with the axotomized distal stump. Expression of MAP1B was also observed in cultured primary Schwann cells from neonatal rats. The properties of the MAP1B protein in cultured Schwann cells were further characterized by Western blot analysis using specific antibodies that recognize the N-terminal, middle and C-terminal domains of MAP1B. All of these antibodies detected a protein of 320-340 kDa demonstrating that MAP1B expressed by Schwann cells is very similar, or identical, to MAP1B expressed by neurons. The phosphorylation of MAP1B in Schwann cells was also studied using monoclonal antibodies (mAb) that recognize specific phosphorylation epitopes. The results indicated that the expression of MAP1B in Schwann cells exhibited a differential phosphorylation state that was recognized by mAb 1B6 but not by other mAbs, including 1B-P, 150 and RT97, that recognize phosphorylated MAP1B in growing axons. We therefore conclude that MAP1B is expressed in Schwann cells during both development and axonal regeneration, suggesting that the developmental pattern of MAP1B in these cells is recapitulated in adult Schwann cells during the early stages of regeneration and remyelination of injured peripheral axons. The presence of MAP1B in Schwann cells may support morphological changes of these cells, particularly the formation of processes prior to their differentiation into myelin forming Schwann cells.
Using the cDNA-representative differences analysis (cDNA-RDA) approach, we identified a novel gene, TFAR19 (TF-1 cell apoptosis related gene-19), from TF-1 cells undergoing apoptosis. The human TFAR19 encodes a protein which shares significant homology to the corresponding proteins of species ranging from yeast to mice. TFAR19 exhibits a ubiquitous expression pattern and its expression is upregulated in the tumor cells undergoing apoptosis. Overexpression of TFAR19 in tumor cells enhances apoptosis triggered by growth factor or serum deprivation. We propose that TFAR19 may play a general role in the apoptotic process.