Biomedical subjects
Publications and source records attributed to J Gao.
A novel human leukocyte antigen (HLA)-DQB1 allele, DQB1*020102, was detected in a 28-year-old woman of Han ethnic in Guangzhou, China. Compared with HLA-DQB1*020101 and HLA-DQB1*0202, they differed in only one nucleotide at the position 167 (C to T) of exon 2, which was a highly conserved position. This is a synonymous mutation, which does not cause any change in the amino acid sequence of mature protein.
This study was performed to examine the inhibitory effects of soybean isoflavones on estrogen-stimulated gene expression of the uteri in ovarectomized mice. Especially when compared with the inhibitory effect of genistein and daidzein as aglycosides described in our previous report, subcutaneous administration of the glycoside genistin significantly decreased the levels of estradiol-17beta (E2)-induced expressions of c-jun, interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha mRNAs (p < 0.005, p < 0.05 and p < 0.05, respectively) and seemingly proteins in the mice uteri, whereas the glycoside daidzin weakly inhibited E2-stimulated expressions of c-fos and IL-1alpha. Both genistin and daidzin seemed to have a weaker inhibitory effect than that of genistein and daidzein on the expression of estrogen-stimulated genes. It is suggested that those glycosides are naturally derived and generally absorbed from plant foods and might prevent E2-related endometrial carcinogenesis.
This study investigated the local drug pharmacokinetics of intralesional drug delivery after radiofrequency ablation of the liver. We hypothesized that the tissue architecture damaged by the ablation process facilitates the drug penetration in the liver and potentially enlarges the therapeutic margin in the local treatment of cancer. The delivery rate and tissue distribution of carboplatin, an anticancer agent, released from poly(D,L-lactide-co-glycolide) implants into rat livers after radiofrequency ablation were quantified by atomic absorption spectroscopy. Results showed that carboplatin clearance through blood perfusion was significantly slower in the ablated livers, leading to a more extensive tissue retention and distribution of the drug. The concentration of Pt at the implant-tissue interface ranged from 234 to 1440 microg Pt/(g liver) in the ablated livers over 144 h versus 56 to 177 microg Pt/(g liver) in the normal tissue. The maximum penetration distance at which Pt level reached above 6 microg/g (calculated based on a reported IC90 value for carboplatin) was 8-10 mm and 4-6 mm in ablated and normal liver, respectively. Histological analysis of the necrotic lesions showed widespread destruction of tissue structure and vasculature, supporting the initial hypothesis. This study demonstrated that intralesional drug delivery could provide a sustained, elevated concentration of anticancer drug at the ablation boundary that has the potential to eliminate residual cancer cells surviving radiofrequency ablation.
Polylactic acid (PLA) powders have been used as vector particles to carry pharmaceutical material. Drugs incorporated in the PLA powder can be retained in the lung for a longer period and may be more effective than free-form drugs. A new formulation of L-PLA dry powder, which was easy to disperse in the air, was produced by using a supercritical technology. The L-PLA powder was characterized in terms of physical particle size and aerodynamic size as generated with a Turbuhaler dry powder inhaler (DPI). Electron microscopy analysis of the particles indicated that they were individual particles in bulk form and became aggregate particles after generation by the Turbuhaler. Aerodynamic particle size analysis using both an Aerodynamic Particle Sizer (APS) aerosol spectrometer and Andersen impactor showed that the aerodynamic size decreased as the flow rate in the Turbuhaler increased from 28.3 to 90 L min(-1). Deposition patterns in the human respiratory tract were estimated using a realistic physical replica of human airways. Deposition of the L-PLA was high (80.8%) in the oral airway at 28.3 L min(-1) and an average of 73.4% at flow rates of 60 and 90 L min(-1). In the lung region, the deposition totaled 7.2% at 28.3 L min(-1), 18.3% at 60 L min(-1), and 17.6% at 90 L min(-1). These deposition patterns were consistent with aerodynamic size measurement, which showed 76 to 86% deposition in the USP/EP (US Pharmacopoeia/European Pharmacopoeia) induction port. As the flow rate increased, fewer aggregates were formed resulting in the smaller aerodynamic particles. As a result, more particles penetrated the oral airways and were available for deposition in the lung. Our results showed that L-PLA particles as manufactured by the supercritical technology could be used in a DPI that does not require the use of carrier particles to facilitate aerosol delivery.
We present data on the inclusive scattering of polarized electrons from a polarized 3He target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5 degrees. Our data include measurements from the quasielastic peak, through the nucleon resonance region, and beyond, and were used to determine the virtual photon cross-section difference sigma(1/2)-sigma(3/2). We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of four-momentum transfer squared Q2 of 0.1-0.9 GeV2.
The ratio of the electric and magnetic form factors of the proton G(E(p))/G(M(p)), which is an image of its charge and magnetization distributions, was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the recoil polarization technique. The ratio of the form factors is directly proportional to the ratio of the transverse to longitudinal components of the polarization of the recoil proton in the elastic e(-->)p---> e(-->)p reaction. The new data presented span the range 3.5< Q(2)< 5.6 GeV(2) and are well described by a linear Q(2) fit. Also, the ratio sqrt[Q(2)] F(2(p))/F(1(p)) reaches a constant value above Q(2) = 2 GeV(2).
FGD1 mutations result in faciogenital dysplasia, an X-linked human disease that affects skeletogenesis. FGD1 encodes a guanine nucleotide exchange factor (GEF) that specifically activates the Rho GTPase Cdc42. To gain insight into the function of FGD1, we have isolated and characterized fgd-1, the Caenorhabditis elegans homolog of the human FGD1 gene. Comparative sequence analyses show that fgd-1 and FGD1 share a similar structural organization and a high degree of sequence identity throughout shared signaling domains. In nematodes, interference with fgd-1 expression results in excretory cell abnormalities and cystic dilation of the excretory cell canals. Molecular lesions associated with two exc-5 alleles affect the fgd-1 gene, and fgd-1 transgenic expression rescues the Exc-5 phenotype. Together, these data confirm that the fgd-1 transcript corresponds to the exc-5 gene. Transgenic expression studies show that fgd-1 has a limited pattern of expression that is confined to the excretory cell during development, a finding that suggests that the C.elegans FGD-1 protein might function in a cell autonomous manner. Serial observations indicate that fgd-1 mutations lead to developmental excretory cell abnormalities that cause cystic dilation and interfere with canal process extension. Based on these data, we conclude that fgd-1 is the C.elegans homolog of the human FGD1 gene, a new member of the FGD1-related family of RhoGEF genes, and that fgd-1 plays a critical role in excretory cell morphogenesis and cellular organization.
Arterial restenosis is responsible for the high failure rates of vascular reconstruction procedures. Local sustained drug delivery has shown promise in the prevention of restenosis. The drug release rate from mithramycin-loaded EVA matrices (0.1%) was evaluated, and their antirestenotic effect was studied in the rat carotid model and rabbit model of vascular grafts. The modulation of c-myc expression by mithramycin treatment was examined by immunohistochemistry in the rat carotid model. The proliferative response of injured rat arteries was studied by bromdeoxyuridine (BrdU) immunostaining. The impact of mithramycin treatment on vasomotor responses of the venous segments grafted into arterial circulation was studied ex vivo using vasoreactive compounds. Mithramycin was released exponentially from EVA matrices in PBS. Matrices co-formulated with PEG-4600 revealed enhanced release kinetics. The perivascular implantation of drug-loaded EVA-PEG matrices led to 50% reduction of neointimal formation, and reduced the c-myc expression and BrdU labeling in comparison to control implants. Decreased sensitivity of mithramycin-treated grafts to serotonin-induced vasoconstriction was observed. Local perivascular mithramycin treatment limits the functional alteration caused by the grafting of venous segments in high-pressure arterial environment, and potently inhibits stenosis secondary to grafting and angioplasty injury. The antirestenotic effect is associated with reduced c-myc expression and with subsequent decrease in SMC proliferation.
The genetic diversity among 95 isolates from Astragalus adsurgens was investigated using molecular biological methods. All of the isolates and 24 reference strains could be differentiated by AFLP, REP-, ERIC- and BOX-PCR fingerprinting analysis. By cluster analysis of the data, 31 AFLP and 38 Rep-PCR genomic groups were delineated, indicating considerable genetic diversity among the isolates. Fifty-four representative strains were further analyzed by RFLP of PCR-amplified 16S and 23S rDNA, revealing 26 rDNA genotypes among the isolates. The phylogenetic relationship of the isolates was determined by partial sequencing of 16S rRNA genes of 16 strains. The results suggest that the A. adsurgens rhizobia belong to the genera Agrobacterium, Mesorhizobium, Rhizobium and Sinorhizobium.
OBJECTIVE: To assess the relation between the scales of Job Demand control Model (or "Job strain") and the prevalence of hypertension. METHODS: A standardized questionnaire base-line survey was conducted among 1,556 male and female employees aged 18-65 in two factories of the Capital Steel and Iron Company, Beijing, in 1997 to investigate the socio-demographic factors and job strain so as to identify the major risks of hypertension. RESULTS: The prevalence of hypertension increased from 6.5% to 21.2% with an age-adjusted relative prevalence ratio (95% CI) of 3.26 (2.30, 4.41) when the job strain pattern changed from high control and low demand to moderate control and moderate demand and further to low control and high demand among the male employees. After adjustment for confounding effects from age, education, body mass index, smoking, alcohol consumption, and physical activity, the odds ratio (95% CI) was attenuated to 2.31 (1.45, 3.81). Such a phenomenon was not typical among females. CONCLUSION: The risk of hypertension was elevated with the increase of job strain in men.
The crystal structure of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) in complex with MgADP has been determined at 1.5-A resolution with a crystallographic R factor of 0.191. The solution structure of HPPK in complex with Mg(2+) and beta,gamma-methyleneadenosine 5'-triphosphate (MgAMPPCP) has been determined using a simulated annealing protocol with 3,523 experimental NMR restraints. The root mean square deviation of the ensemble of 20 refined conformers that represent the solution structure from the mean coordinate set derived from them is 0.74 +/- 0.26 A for all backbone atoms and 0.49 +/- 0.22 A when residues Pro(14), Pro(44)-Gln(50), and Arg(84)-Pro(91) are excluded. Binding of MgADP causes significant changes in the conformation and dynamical property of three loops of HPPK that are involved in catalysis. A dramatic, unusual conformational change is that loop 3 moves away from the active center significantly with some residues moving by >17 A. The binding of MgADP also stabilizes loop 1 and loop 3 but makes loop 2 more mobile. Very similar conformational and dynamical changes are observed in the NMR solution structure of HPPK.MgAMPPCP. The conformational and dynamical changes may play important roles in both substrate binding and product release in the catalytic cycle.
Mutations of the cardiac beta-myosin heavy-chain (beta-MHC) gene cause hypertrophic cardiomyopathy (HCM). Recent genotype-phenotype correlation studies have shown that mutations carry prognostic significance. We studied five unrelated Chinese families with hypertrophic cardiomyopathy. Exons 3-27 and 40 of the beta-MHC gene were screened with both the polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method and the cycle sequencing of the PCR products. A previously reported heterozygous mutation Arg719Gln (arginine-->glutamine in codon 719) in exon 19 was found in one family. The proband is a 30-year-old female diagnosed at age of 25 years when she presented with symptoms of chest pain, palpitations, and frequent incidents of dizziness and syncope. A two-dimensional echocardiogram showed moderate asymmetrical septal hypertrophy with left atrial enlargement. There was no obstruction of the left ventricular outflow tract (LVOT). The patient also developed atrial fibrillation. The proband's mother and one of her sisters had similar clinical manifestations and both died suddenly at the age of 38 years. In addition, two silent nucleotide substitutions (ACT63ACC, TTT244TTC) in the cardiac beta-MHC gene were identified in the other four families. These synonymous mutations did not cosegregate with the disease in the families and they were also present in the 60 healthy and age-matched control subjects. Of the five families studied, we did not find any missense mutation in the remaining four families. The missense mutation Arg719Gln found in the Chinese family is associated with a malignant phenotype of severe clinical symptoms and poor survival prognosis. This mutation also causes atrial enlargement and atrial fibrillation. Our study provides further evidence that the mutation, which alters the charge of the myosin heavy chain, is associated with a serious clinical outcome.
FXV673 is a novel, potent, and selective factor Xa (FXa) inhibitor. FXV673 inhibited human, dog, and rabbit FXa with a K(i) of 0.52, 1.41, and 0.27 nM, respectively. FXV673 also displayed excellent specificity toward FXa relative to other serine proteases. It showed selectivity of more than 1000-fold over thrombin, activated protein C (aPC), plasmin, and tissue-plasminogen activator (t-PA). FXV673 prolonged plasma activated partial thromboplastin time (APTT) and prothrombin time (PT) in a dose-dependent fashion. In the APTT assays, the concentrations (microM) required for doubling coagulation time were 0.41 (human), 0.65 (monkey), 1.12 (dog), 0.25 (rabbit), and 0.80 (rat). The concentrations (microM) required in the PT assays were 1.1 (human), 1.32 (monkey), 2.31 (dog), 0.92 (rabbit), and 1.69 (rat). A coupled-enzyme assay was performed to measure thrombin activity following prothrombinase conversion of prothrombin to thrombin. FXV673 showed IC(50)s of 1.38 and 2.55 nM, respectively, when artificial phosphatidylserine/phosphatidylcholine (PS/PC) liposomes or fresh platelets were used as the phospholipid source for prothrombinase complex formation. It was demonstrated that FXV673 could inhibit further thrombin generation in the prothrombinase complex using PS/PC liposomes. FXV673 dose-dependently prolonged the time to vessel occlusion and inhibited thrombus formation in well-characterized canine models of thrombosis. Interspecies extrapolation (approximately 2.5-fold higher sensitivity for FXa inhibition in human than in dog) suggested that 100 ng/ml of FXV673 would be an effective plasma concentration for clinical studies. Currently FXV673 is undergoing clinical studies to be developed as an antithrombotic agent.
This article provides evidence of a new class of compounds, 1,3-diaryl-[1H]-pyrazole-4-acetamides, initially identified from their ability to increase glucose transport in an adipocyte and muscle cell line and ultimately demonstrating dramatic glucose lowering in ob/ob mice, a diabetic animal model. The lead compound, 1, possessed some behavioral-like effects which were removed by structural variation during the course of this investigation. Specifically, 11g (R1 = meta-CF(3), Ar2 = 4'biphenyl, R3 = diethylamide) illustrated the potency of this series with ED(50) values for glucose lowering in ob/ob mice of 3.0 mg/kg/day. Concomitant with its effect on glucose lowering, 11g also caused a 50% reduction in insulin levels consistent with an agent that increases whole body insulin sensitivity. 11g showed favorable pharmacokinetic data with acceptable absorption, negligible metabolism, and good duration of action. 11g demonstrated no appreciable adipogenic effect through PPAR gamma agonism, a characteristic of the thiazolidinediones (TZD), and so represents a potentially new class of agents for the treatment of diabetes.
Some chelators of the pyridoxal isonicotinoyl hydrazone class have antiproliferative activity that is far greater than desferrioxamine (DFO). In this study, DFO was compared with one of the most active chelators (311) on the expression of molecules that play key roles in cell-cycle control. This was vital for understanding the role of iron (Fe) in cell-cycle progression and for designing chelators to treat cancer. Incubating cells with DFO, and especially 311, resulted in a decrease in the hyperphosphorylated form of the retinoblastoma susceptibility gene product (pRb). Chelators also decreased cyclins D1, D2, and D3, which bind with cyclin-dependent kinase 4 (cdk4) to phosphorylate pRb. The levels of cdk2 also decreased after incubation with DFO, and especially 311, which may be important for explaining the decrease in hyperphosphorylated pRb. Cyclins A and B1 were also decreased after incubation with 311 and, to a lesser extent, DFO. In contrast, cyclin E levels increased. These effects were prevented by presaturating the chelators with Fe. In contrast to DFO and 311, the ribonucleotide reductase inhibitor hydroxyurea increased the expression of all cyclins. Hence, the effect of chelators on cyclin expression was not due to their ability to inhibit ribonucleotide reductase. Although chelators induced a marked increase in WAF1 and GADD45 mRNA transcripts, there was no appreciable increase in their protein levels. Failure to translate these cell-cycle inhibitors may contribute to dysregulation of the cell cycle after exposure to chelators. (Blood. 2001;98:842-850)
BACKGROUND: Once paracrine growth factors are secreted by androgen receptor expressing prostatic stromal cells, they diffuse across the basement membrane of glandular acini, where they bind to epithelial cell surface receptors. This binding stimulates signaling pathways that regulate both the rate of proliferation and apoptosis of prostate epithelial cells. In the present studies, the role of mixed lineage kinases (MLKs) in these signaling processes were studied using a pharmacological approach. METHODS: The indolocarbazole CEP-1347 (KT 7515) is a potent inhibitor of kinase activity of MKLs. Male rats were treated with CEP-1347 (1 mg/kg of body weight/day) to determine whether inhibition of the MLKs can prevent androgen ablation (i.e. castration) induced apoptosis of prostatic epithelial cells, using as indexes total ventral prostatic DNA content and the percentage of ventral prostatic epithelial cells whose DNA can be terminal transferase end-labeled. In addition, animals previously castrated a week earlier were treated daily with either vehicle or CEP-1347 and exogenous androgen replacement to induce the proliferative re-growth of the prostatic epithelial cells. After 1 week of treatment, the total ventral prostatic DNA content in the vehicle vs. CEP-1347 groups was compared. RESULTS: Using the National Center for Bio-Informatics data bank, MLK2, MLK3, and DLK members of the MLK family are expressed by the normal prostate. Inhibition of the MLKs with CEP-1347 did not affect the kinetics of apoptosis of prostatic epithelial cells induced by androgen ablation. In addition, such MLK inhibition did not prevent androgen replacement induced proliferative regrowth of the prostate epithelium in castrated animals. CONCLUSIONS: Signaling through the MLK family is not involved in either the androgen-induced proliferation or the androgen ablation-induced apoptosis of prostatic epithelial cell in the rat.
Normal adult prostate epithelium of both human and rat origin was transplanted with Matrigel into intact or androgen-ablated (i.e., castrated) nude mice. Within these transplants, an influx of mouse mesenchymal cells was one of the earliest events to occur resulting in the development of a collar of smooth muscle cells and fibroblasts surrounding the transplanted epithelium. A subset of these surrounding stromal cells express androgen receptor (AR). The surrounded transplanted epithelium initially expresses high molecular weight cytokeratins characteristic of prostatic basal cells and AR. In both intact and androgen-ablated hosts, this epithelium subsequently develops a patent lumen producing a rudimentary glandular acini. Only in the nonablated hosts, however, do these rudimentary acini undergo a further proliferative growth phase, as determined by Ki67 immunocytochemical stainings and the development of a low molecular weight cytokeratin positive layer of luminal (i.e., secretory) epithelial cells. Because AR is expressed in both the donor epithelium and host (i.e., mouse) stromal cells, this androgen-stimulated growth response could involve either autocrine pathways initiated within donor normal adult epithelial cells themselves or paracrine pathways initiated within the AR-expressing subset of mouse stromal cells. To resolve this issue, mice carrying the testicular feminized mutation in the X-linked AR gene were cross-bred to AR-wt nude mice to produce AR-null nude male mice. None of the cells in these AR-null nude male mice express functional AR protein. Therefore, these animals can be used to prevent any possibility of host stromal cell paracrine involvement in initiating an androgen-stimulated growth response when normal adult or malignant prostatic epithelial cells are transplanted into these null hosts. In these AR-null nude male mice, the androgen-stimulated growth of normal adult prostatic epithelial cells did not occur (i.e., androgen-induced growth response of normal prostatic epithelial cells requires stromal cell paracrine involvement). In contrast, using four different prostatic cancer models (i.e., human PC-82, human LNCaP, human LAPC-4, and rat R3327G), the androgen-stimulated growth of prostatic cancer cells occurred identically in both AR-null and AR-wt nude male mice (i.e., a direct autocrine mechanism is responsible for androgen-stimulated growth of malignant prostatic epithelial cells). In summary, a fundamental change in the mechanism for androgen-stimulated growth occurs during the transformation from normal to malignant prostatic epithelial cells.
We measured the cross section and response functions for the quasielastic 16O(e,e'p) reaction for missing energies 25< or =E(m)< or =120 MeV at missing momenta P(m)< or =340 MeV/c. For 25<E(m)<50 MeV and P(m) approximately 60 MeV/c, the reaction is dominated by a single 1s(1/2) proton knockout. At larger P(m), the single-particle aspects are increasingly masked by more complicated processes. Calculations which include pion exchange currents, isobar currents, and short-range correlations account for the shape and the transversity, but for only half of the magnitude of the measured cross section.