Biomedical subjects
Publications and source records attributed to C Ma.
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In response to stressful events, neonatal mice emit ultrasonic vocalizations (USVs), which are suppressed by BZ agonists. The present study examined the role of the benzodiazepine/alpha1 (BZ/alpha1) receptor subtype in the suppression engendered by the BZ/alpha1-preferring agonist zolpidem and the nonselective BZ agonists triazolam and diazepam. The role of BZ receptor subtypes was explored further by conducting antagonism studies using the BZ/alpha1-preferring antagonist beta-carboline-3-carboxylate-t-butyl ester (beta-CCt), in comparison with the nonselective BZ antagonist flumazenil. Mouse pups (CFW strain) were separated from their dam and littermates at day 7, and placed for 4 min in a test chamber with reduced ambient temperature (19 +/- 1 degrees C) for recording USVs, motor incoordination (measured as a pup rolling on its back per grid cross), and body temperature. Zolpidem, triazolam, and diazepam suppressed USVs in a dose-dependent manner, concomitant with increases in incoordination and augmentation of hypothermia. These effects of the three BZ agonists were blocked by flumazenil in a manner consistent with surmountable antagonism. The ability of zolpidem, but not triazolam or diazepam, to suppress USVs and augment hypothermia was antagonized by beta-CCt, whereas the increase in motor incoordination engendered by zolpidem, triazolam, and diazepam was not sensitive to beta-CCt administration. Collectively, these results suggest that zolpidem suppresses distress USVs in mouse pups by a mechanism distinct from that of typical BZs. Furthermore, suppression of distress USVs by zolpidem may involve BZ/alpha1 receptors and a nonanxiolytic mechanism, such as hypothermia.
OBJECTIVE: To determine the effect of the pentanucleotide deletion polymorphism adjacent to a consensus splice site in intron 17 of alpha 2-macroglobulin(A2M) gene on the development of late-onset Alzheimer's disease (LOAD) in the Han Chinese in Guangzhou area. METHODS: A2M and apolipoprotein E genotypes were examined by polymerase chain reaction(PCR) and restriction fragment length polymorphism (RFLP) techniques in the patients(32 men and 65 women) with LOAD and age-matched healthy elderly Chinese subjects (57 men and 54 women). RESULTS: The A2M gene deletion allele frequency was 2.6% in the cases with LOAD and 2.7% in the controls. In the LOAD cases, the frequency of apoE-epsilon4 increased significantly (Z=3.32, P<0.01). ApoE-epsilon4 was associated with LOAD (RR=2.67, chi(2)=10.71, P<0.01) while the A2M deletion polymorphism was not associated with LOAD even the samples were stratified according to the presence of the apoE-epsilon4 allele. CONCLUSION: The above data demonstrate that there is no evidence for the association of A2M polymorphism with the development of LOAD in the Han Chinese population in Gaungzhou.
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OBJECTIVE: To improve the quality of papers on clinical diagnostic tests. METHODS: Articles of diagnostic tests published in the Chinese Journal of Oncology in the year 1990 were surveyed by cluster sampling method. RESULTS: In the 23 articles surveyed, immunoassays constituted the largest category, accounting for 39.1% (9/23), followed by biochemical markers and radiological tests, accounting for 17.4% (4/23) and 13.0%(3/23), respectively. Of the 23 articles, 19 (82.6%) employed a well-defined "gold standard", 14 (60.9%) correctly calculated sensitivity and specificity. The interpretation of the test was stated to be "blind" in only 39.1%(9/32). In only one paper were all the seven methodologic criteria adhered. Less than 60% of the articles followed more than four of the seven methodologic criteria, and in 2 articles only one of the criteria was met with. CONCLUSION: Although due attention has been paid to the methodologic criteria of assessing diagnostic tests, the quality of the articles surveyed needs to be improved.
OBJECTIVE: To improve clinical knowledge of Peutz-Jeghers syndrome. METHODS: Eight patients with Peutz-Jeghers syndrome from 1984 to 1998 in our hospital were retrospectively reviewed and analyzed in the present study. RESULT: The result of this analysis showed that there were 4 patients appeared with family histories of Peutz-Jeghers syndrome. All of the included patients admitted to the hospital with various complications, and eventually received surgical interventions for these complications, among which, 6 of them had intestinal obstructions mostly (5/6) due to small bowel intussusception, and 2 of them suffered with hemafecia. Post-operative recoveries were generally satisfactory with zero mortality. CONCLUSION: Peutz-Jeghers syndrome is an uncommon digestive dominant hereditary disease. The diagnosis of it with history, symptoms, signs, and proper examinations usually is not difficult Surgical interventions are necessary once complications occur.
Utilizing a functional screen in the yeast Saccharomyces cerevisiae we identified mammalian proteins that activate heterotrimeric G-protein signaling pathways in a receptor-independent fashion. One of the identified activators, termed AGS1 (for activator of G-protein signaling), is a human Ras-related G-protein that defines a distinct subgroup of the Ras superfamily. Expression of AGS1 in yeast and in mammalian cells results in specific activation of Galpha(i)/Galpha(o) heterotrimeric signaling pathways. In addition, the in vivo and in vitro properties of AGS1 are consistent with it functioning as a direct guanine nucleotide exchange factor for Galpha(i)/Galpha(o). AGS1 thus presents a unique mechanism for signal integration via heterotrimeric G-protein signaling pathways.
Pattern recognition proteins function in innate immune responses by binding to molecules on the surface of invading pathogens and initiating host defense reactions. We report the purification and molecular cloning of a cDNA for a 53-kDa beta1,3-glucan-recognition protein from the tobacco hornworm, Manduca sexta. This protein is constitutively expressed in fat body and secreted into hemolymph. The protein contains a region with sequence similarity to several glucanases, but it lacks glucanase activity. It binds to the surface of and agglutinates yeast, as well as gram-negative and gram-positive bacteria. Beta1,3-glucan-recognition protein in the presence of laminarin, a soluble glucan, stimulated activation of prophenoloxidase in plasma, whereas laminarin alone did not. These results suggest that beta1,3-glucan-recognition protein serves as a pattern recognition molecule for beta1,3-glucan on the surface of fungal cell walls. After binding to beta1,3-glucan, the protein may interact with a serine protease, leading to the activation of the prophenoloxidase cascade, a pathway in insects for defense against microbial infection.
Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin's lymphoma, is clinically heterogeneous: 40% of patients respond well to current therapy and have prolonged survival, whereas the remainder succumb to the disease. We proposed that this variability in natural history reflects unrecognized molecular heterogeneity in the tumours. Using DNA microarrays, we have conducted a systematic characterization of gene expression in B-cell malignancies. Here we show that there is diversity in gene expression among the tumours of DLBCL patients, apparently reflecting the variation in tumour proliferation rate, host response and differentiation state of the tumour. We identified two molecularly distinct forms of DLBCL which had gene expression patterns indicative of different stages of B-cell differentiation. One type expressed genes characteristic of germinal centre B cells ('germinal centre B-like DLBCL'); the second type expressed genes normally induced during in vitro activation of peripheral blood B cells ('activated B-like DLBCL'). Patients with germinal centre B-like DLBCL had a significantly better overall survival than those with activated B-like DLBCL. The molecular classification of tumours on the basis of gene expression can thus identify previously undetected and clinically significant subtypes of cancer.
Pharmacophore/receptor models for three recombinant GABA(A)/BzR subtypes (alpha1beta3gamma2, alpha5beta3gamma2, and alpha6beta3gamma2) have been established via an SAR ligand-mapping approach. This study was based on the affinities of 151 BzR ligands at five distinct (alpha1-3,5,6beta3gamma2) recombinant GABA(A)/BzR receptor subtypes from at least nine different structural families. Examination of the included volumes of the alpha1-, alpha5-, and alpha6-containing subtypes indicated that region L(2) for the alpha5-containing subtype appeared to be larger in size than the analogous region of the other receptor subtypes. Region L(Di), in contrast, appeared to be larger in the alpha1 subtype than in the other two subtypes. Moreover, region L(3) in the alpha6 subtype is either very small or nonexistent in this diazepam-insensitive subtype (see Figure 16 for details) as compared to the other subtypes. Use of the pharmacophore/receptor models for these subtypes has resulted in the design of novel BzR ligands (see 27) selective for the alpha5beta3gamma2 receptor subtype. alpha5-Selective ligand 27 when injected directly into the hippocampus did enhance memory in one paradigm (Bailey et al., unpublished observations); however, systemic administration of either 9 or 27 into animals did not provide an observable enhancement. This result is in complete agreement with the observation of Liu (1996). It has been shown (Liu, 1996; Wisden et al., 1992) that in the central nervous system of the rat (as well as monkeys and pigeons) there are several native subtypes of the GABA(A) receptor which exhibit different functions, regional distributions, and neuronal locations. Although 27 binds more potently at alpha5beta3gamma2 receptor subtypes and is clearly an inverse agonist (Liu et al., 1996; Liu, 1996), it is possible that this ligand acts as an agonist at one or more subtypes. Liu (1996) clearly showed that a number of imidazobenzodiazepines were negative modulators at one subtype and agonists at another. Therefore, selectivity for a particular subtype at this point is not sufficient to rule out some physiological effect at other GABA(A)/BzR subtypes. The inability of 27 to potentiate memory when given systemically is again in support of this hypothesis, especially since alpha1beta2gamma2 subtypes are distributed throughout the brain (Wisden et al., 1992). A drug delivered systemically is far more likely to interact with all subtypes than one delivered to a specific brain region. This observation (systemic vs intrahippocampal) provides further support for the design of more subtype-specific ligands at the BzR to accurately define their pharmacology, one key to the design of new drugs with fewer side effects.
Uniformly (15)N-labeled samples of membrane proteins with helices aligned parallel to the membrane surface give two-dimensional PISEMA spectra that are highly overlapped due to limited dispersions of (1)H-(15)N dipolar coupling and (15)N chemical shift frequencies. However, resolution is greatly improved in three-dimensional (1)H chemical shift/(1)H-(15)N dipolar coupling/(15)N chemical shift correlation spectra. The 23-residue antibiotic peptide magainin and a 54-residue polypeptide corresponding to the cytoplasmic domain of the HIV-1 accessory protein Vpu are used as examples. Both polypeptides consist almost entirely of alpha-helices, with their axes aligned parallel to the membrane surface. The measurement of three orientationally dependent frequencies for Val17 of magainin enabled the three-dimensional orientation of this helical peptide to be determined in the lipid bilayer.
Twelve amino acid residues corresponding to an "EF-hand" calcium-binding site were added to the N-terminus of a protein, providing a specific lanthanide ion binding that weakly orients the protein in solution. A comparison of spectra of the protein with and without the EF-hand residues demonstrates that the structure of the native protein is not perturbed by this modification, since there are minimal chemical shift changes. With a lanthanide but not calcium bound to the EF-hand, the protein is weakly oriented by the magnetic field, since residual dipolar couplings can be measured. Since the signs and magnitudes of the couplings varied with the type of lanthanide, this demonstrated the ability to obtain multiple orientations of the protein in solution. The sample is a membrane protein in lipid micelles that disrupted the commonly employed bicelle and filamentous phage solutions; therefore, the addition of a specific metal binding site in the form of an EF-hand may provide a general approach to orienting proteins where the addition of external agents is problematic. An additional benefit is that the lanthanide ions perturb the protein resonances in ways that provide unique orientational and distance constraints.
BACKGROUND: Gene therapy has shown limited efficacy for treating congenital diseases, partly due to temporary gene expression and host immune responses. Such results suggest that gene therapy is ideal for chronic wound treatment where limited duration of target gene expression is required. This study tested the wound healing effects of topically applied platelet-derived growth factor (PDGF)-A or -B chain DNA plasmids embedded within a collagen lattice. MATERIALS AND METHODS: Four 6-mm dermal ulcer wounds were created in the ears of young adult New Zealand White rabbits made ischemic by division of the central and rostral arteries. Wounds were treated with lyophilized collagen containing PDGF-B DNA (1.0-3.0 mg), PDGF-A DNA (1.0 mg), irrelevant DNA (1.0 mg), or collagen alone. Wounds were dressed and harvested after 10 days for measurement of granulation tissue formation, epithelialization, and wound closure. Results were evaluated with a paired two-tailed Student t test, with P values < 0.05 considered significant. RESULTS: PDGF-B DNA increased new granulation tissue (NGT) formation up to 52% and epithelialization 34% compared with controls. Wound closure was increased up to threefold. At 1.0 mg DNA, PDGF-A and PDGF-B stimulated similar responses. No difference in NGT or epithelialization was seen between control groups. CONCLUSIONS: PDGF DNA gene therapy is effective at accelerating wound healing in ischemic dermal ulcers and provides a viable alternative to peptide growth factor therapy.
Gene therapy has yet to achieve reproducible clinical efficacy, due to inadequate gene delivery, inadequate gene expression, or dose-limiting toxicity. We have developed a gene therapy technology for tissue repair and regeneration that employs a structural matrix for DNA delivery. The matrix holds the DNA vector at the treatment site and provides a scaffolding for in-growth and accumulation of repair cells and efficient DNA transfection. We now report, for the first time, matrix-mediated delivery of targeted DNA vectors for soft tissue repair. A collagen matrix was used to deliver an adenoviral vector encoding platelet-derived growth factor-B (AdPDGF-B), resulting in efficient transgene expression in vitro and in vivo. Increases in the overall levels of expression and in the relative amounts of secreted PDGF-BB were achieved when AdPDGF-B was conjugated to fibroblast growth factor (FGF2) such that the virus was targeted for cellular uptake via FGF receptors. Matrix-mediated delivery of AdPDGF-B enhanced wound healing responses in vivo, and FGF2 targeting generated effects comparable to nontargeted vectors at significantly lower doses. Therefore, matrix-mediated delivery in combination with FGF2 targeting overcomes some of the safety and efficacy limitations of current gene therapy strategies and is an attractive therapeutic approach for tissue repair and regeneration.
One new germacranolide (named caruifolin A) and three new guaiane dimers (caruifolins B-D), together with six known compounds, were isolated from the aerial parts of Artemisia caruifolia. The structures were determined by chemical and spectroscopic methods.
From a methanolic extract of the wood of Xanthoceras sorbifolia, two new compounds, 29-hydroxy-3-oxotirucalla-7,24-dien-21-oic acid (3, xanthocerasic acid) and epigallocatechin-(4beta-->8, 2beta-->O-7)-epicatechin (6), were isolated, together with 11 known compounds. Of the isolated compounds, 3-oxotirucalla-7, 24-dien-21-oic acid (2), oleanolic acid (4), and 6 were found to be inhibitory substances against human immunodeficiency virus (HIV-1) protease, with their 50% inhibitory concentrations (IC(50)) being 20, 10, and 70 microg/mL, respectively. Condensed tannins of high molecular weights with epicatechin and epiafzelechin as the main extender units were found to be the most active principles of this plant (IC(50) values ca. 6.0 microg/mL).
PTLF, the Populus trichocarpa homolog of LEAFY (LFY) and FLORICAULA, was cloned to assess its function in a dioecious tree species. In situ hybridization studies showed that the gene was expressed most strongly in developing inflorescences. Expression was also seen in leaf primordia and very young leaves, most notably in apical vegetative buds near inflorescences, but also in seedlings. Although ectopic expression of the PTLF cDNA in Arabidopsis accelerated flowering, only one of the many tested transgenic lines of Populus flowered precociously. The majority of trees within a population of 3-year-old transgenic hybrid Populus lines with PTLF constitutively expressed showed few differences when compared to controls. However, phenotypic effects on growth rate and crown development, but not flowering, were seen in some trees with strong PTLF expression and became manifest only as the trees aged. Competence to respond to overexpression of LFY varied widely among Populus genotypes, giving consistent early flowering in only a single male P. tremula x P. tremuloides hybrid and causing gender change in another hybrid genotype. PTLF activity appears to be subject to regulation that does not affect heterologously expressed LFY, and is dependent upon tree maturation. Both genes provide tools for probing the mechanisms of delayed competence to flower in woody plants.
Inflammation and tissue trauma during the surgical procedure reduce the peritoneal fibrinolytic capacity. These conditions promote adhesion formation, and are associated with increased expression of transforming growth factor beta 1 (TGF-beta1). The objective of the present study was to investigate whether TGF-beta1 regulates the expression of fibrinolytic components in peritoneal mesothelial cells. Human peritoneal mesothelial cells (HPMC) were cultured and treated with various concentrations of human recombinant TGF-beta1 (0.1, 1.0 and 10 ng/mL) for 24 h. Levels of tissue- and urokinase plasminogen activator (t-PA and uPA), plasminogen activator inhibitor type-1 (PAI-1) and type-2 (PAI-2) mRNA and protein were assessed by quantitative reverse transcriptase polymerase chain reaction (Q-RT-PCR) and ELISA, respectively. HPMC expressed these components at the gene and protein level. TGF-beta1 downregulated, dose-dependently t-PA mRNA and protein to about 50% of control values (p = 0.0010), and doubled PAI-1 protein production (p = 0.0008) compared to untreated controls. Although uPA gene expression increased in cells exposed to TGF-beta1, the corresponding protein concentration in conditioned media did not. PAI-2 was not affected, either at the gene or protein level. In conclusion, the results indicate that fibrinolytic capacity of mesothelial cells is reduced by TGF-beta1, suggesting that peritoneal adhesion formation induced by TGF-beta1 may be mediated, in part, through reduction in fibrin degradation capacity at an early stage of peritoneal tissue repair.