Interaction of human serum albumin with dipalmitoylphosphatidylcholine in spread monolayers at the air/water interface (short communication).
Explore the source record for details and available documents.
1,2-Dipalmitoylphosphatidylcholine↗
Biomedical subjects
J Zhao
Publications and source records attributed to J Zhao.
Cryoablation of human colorectal cancer in vivo in a nude mouse xenograft model.
OBJECTIVE: To establish the minimum required temperature in cryoablation of human colorectal cancer cell lines grown as subcutaneous tumors in mice. METHODS: Male nu/nu nude mice were inoculated by a sc injection of 1 x 10(6) LoVo (n = 30) or C170 (n = 32) cells. After 2 weeks the tumors were frozen using a 3-mm cryotherapy probe (LCS 3000, Cryotech, UK) to temperatures ranging from -8 to -84 degreesC. RESULTS: (LoVo) Of 21 mice evaluable for analysis no tumors recurred in 3 mice which had their tumors frozen to less than -60 degreesC as measured at the presumed tumor/host boundary, whereas all but one tumor recurred in 18 mice which had their tumors frozen to >-60 degreesC. (C170) Of 18 mice evaluable for analysis 14 mice which had their tumors frozen to between -8 and -84 degreesC as measured at the presumed tumor/host boundary developed tumor recurrence. Four mice which had their tumors frozen to -11, -58, -62, and -81 degreesC did not develop tumor recurrence. CONCLUSION: Cryotherapy of subcutaneous human colon cancer xenografts in nude mice results in tumor recurrence if tumors are frozen to temperatures of as low as -60 degreesC (LoVo) or -84 degreesC (C170) with a single freeze-thaw cycle. A critical temperature for the effective cryoablation of human colorectal cancer cell lines grown as subcutaneous tumors in mice with a single freeze-thaw cycle was not defined.
Animals↗
Treatment of hepatocellular carcinoma with the cellular tumor vaccines generated by in vitro modification of tumor cells with non gene transfer approaches.
Anti-tumor immune responses are mediated primarily by T cells. Down regulation of major histocompatibility complex (MHC) and the molecules that costimulate the immune responses is associated with defective signaling of tumor cells for T cell activation. In vitro fusion of autologous tumor cells with antigen presenting cells (APCs) or treatment of tumor cells with a combination of cytokines significantly increased the expression of MHC class I and adhesion molecules on tumor cell surfaces that costimulate host immune responses. The hybrid cells generated by fusion of tumor cells with APCs and the tumor cells treated in vitro with a combination of cytokines and pre-incubated with a bispecific monoclonal antibody (bi-Mab) cross-linking antigen on tumor cells to CD28 on T cells, become immunogenic and able to stimulate naive T cells with generation of tumor specific cytotoxic T cells both in vitro and in vivo. Immunization with the modified tumor cells elicits an immune response mediated by both CD4+ and CD8+ T cells. This response protected against a parental tumor cell challenge and cured established tumors. The approach was effective in both low immunogenic and non-immunogenic tumor systems. Modification of tumor cells with tumor:APC fusion or the two-step procedure may provide a strategy for development of tumor vaccines that is effective for cancer immunotherapy.
Animals↗
Characterization of HetR protein turnover in Anabaena sp. PCC 7120.
The hetR gene plays an important role in heterocyst development and pattern formation in heterocystous cyanobacteria. The hetR gene from Anabaena sp. PCC 7120 was overexpressed in Escherichia coli. Antibodies raised against the recombinant HetR protein (rHetR) were used to characterize metabolism of the HetR of Anabaena sp. PCC 7120 in vivo. HetR was present at a low level when Anabaena sp. PCC 7120 was grown in the presence of combined nitrogen. Shifting from nitrogen repletion conditions to nitrogen depletion conditions led to a two fold increase of HetR in total cell extracts, and most of HetR was located in heterocysts. The amount of HetR in total cellular extracts increased rapidly after shifting to nitrogen depletion conditions and reached a maximum level 3 h after the shift. Isoelectrofocusing electrophoresis revealed that the native HetR had a more acidic isoelectric point than did rHetR. After combined nitrogen was added to the nitrogen-depleted cultures, the degradation of HetR depended on culture conditions: before heterocysts were fully developed, HetR was rapidly degraded; after heterocysts were fully developed, HetR was degraded much more slowly. The distribution of HetR in other species of cyanobacteria was also studied.
Amino Acid Sequence↗
Visual acuity and quality of life outcomes in patients with cataract in Shunyi County, China.
PURPOSE: To measure visual acuity and vision-related quality of life in individuals in rural China operated on for cataract. METHODS: Five thousand fifty-two persons age 50 years and older, 90.9% (5,052/5,555) of a randomly selected population in Shunyi County, were examined in the fall of 1996. Visual functioning and quality of life questionnaires were administered to those with presenting visual acuity less than 6/60 in either eye and to those who were aphakic or pseudophakic. RESULTS: Of the 87 individuals operated on for cataract, 12% (10/87) had presenting visual acuity of 6/18 or more in both eyes, and 24.1% (21/87) had less than 6/60. Twenty-five percent (29/116) of the 116 eyes operated on for cataract had presenting visual acuity of 6/18 or more, and 44.8% (52/116) had less than 6/60. Aphakic cases without glasses and uncorrectable aphakia attributable to surgical complications were common. In a multivariate regression model, including time period of surgery, hospital type, and surgical procedure, only pseudophakia was associated with better outcomes (P = .05). On a scale from 0 (maximum problems) to 100 (no problems), the mean visual functioning score (+/-SD) for the operated-on population was 61.9 +/- 30.0, and 71.0 +/- 31.8 for the quality of life questionnaire. These scores were comparable to those of the unoperated-on population with moderate bilateral blindness (<6/60 to > or =3/60 in the better eye). Visual functioning and quality of life scores were closely correlated with visual acuity in operated-on (r = 0.64 and r = 0.61, respectively) and unoperated-on populations (r = 0.68 and r = 0.59, respectively). CONCLUSIONS: Both clinical and patient-reported cataract surgery outcomes are below what should be achievable. Improvement in outcomes must be given greater emphasis if the potential of cataract surgery in restoring sight is to be realized.
Aged↗
Prevalence of blindness and cataract surgery in Shunyi County, China.
PURPOSE: To estimate the prevalence of blindness and cataract surgery among older adults in rural China. METHODS: Cluster sampling was used in randomly selecting men and women aged 50 years or older for visual acuity testing and an eye examination in 28 villages in Shunyi County. The survey, which was carried out in the fall of 1996, was preceded by a pilot study in which operational methods were refined and quality assurance evaluations carried out. RESULTS: Of 5,555 enumerated subjects > or =50 years of age, 91.5% (5,084/5,555) were examined and 90.9% (5,052/5,555) were tested for visual acuity. In this population, 2.8% (139/5,052) were blind, defined as presenting visual acuity less than 6/60 in both eyes. Blindness was associated with older age and female sex. Cataract was the principal cause of blindness in at least one eye in 48.2% (67/139) of blind people. The ratio of those blind from cataract who were operated on to the those who could have been operated on, cataract surgical coverage, was estimated to be 47.8% (54/113). Cataract surgery was associated with younger age but not sex or education. CONCLUSIONS: Blindness, particularly blindness related to cataract, continues to be a significant problem among the elderly, especially women, in this population-based sample of rural Chinese. Despite an active eye-care program in Shunyi County, only half of those who might benefit from cataract surgery are receiving it.
Age Distribution↗
Differential neurotoxicity of etorphine-like opiates: lack of correlation with their ability to activate opiate receptors.
The present study was undertaken to compare the neurotoxic effects of three etorphine-like opiates (etorphine, dihydroetorphine, and another derivative of oripavine) and heroin with their ability to activate opiate receptors in human neuroblastoma cell line SK-N-SH as well as in two other neuronal cell lines. Neurotoxicity was measured by using [3H]-thymidine incorporation analysis, cell viability measurement and Cytosensor microphysiometry. It was found that, in spite of the very similar molecular structures of these opiates, they displayed significant differences in cytotoxicity, with etorphine and another derivative of oripavine possessing high potency but dihydroetorphine and heroin little effect. However, neurotoxic potency of the opiates was not directly correlated to their ability to activate opioid receptors, as determined by [35S]-guanylyl-5'-O-(gamma-tho)-triphosphate binding assay. These findings provide clear evidence of differential neurotoxicity of etorphine-like opiates, and suggest that the neurotoxicity is not closely related to the molecular configuration required as opioid receptor agonist but is probably associated with the presence of a double bond in the structure.
Animals↗
Epithelium-specific adenoviral transfer of a dominant-negative mutant TGF-beta type II receptor stimulates embryonic lung branching morphogenesis in culture and potentiates EGF and PDGF-AA.
Although exogenous transforming growth factor-beta (TGF-beta) is known to inhibit branching morphogenesis in mouse embryonic lungs in culture, whether the principal negative function of endogenous TGF-beta signaling resides in lung epithelium or mesenchyme remains unresolved. A recombinant adenovirus was constructed, containing a mutated human TGF-beta type II receptor with a truncated cytoplasmic kinase domain. We examined whether this dominant-negative receptor could abolish epithelium-specific endogenous TGF-beta signaling. We introduced the recombinant adenovirus into lung explants via intra-tracheal micro-injection. This resulted in over-expression of exogenous truncated TGF-beta type II receptor only in airway epithelium, not in mesenchyme, as assessed by mRNA level and protein localization. Blockade of endogenous TGF-beta receptor signaling in epithelial endoderm by the mutated dominant-negative TGF-beta type II receptor resulted in significant (65%) stimulation of epithelial branching morphogenesis, while exogenous TGF-beta no longer downregulated epithelial PCNA immunoreactivity and surfactant protein C (SP-C) expression. Additionally, the mitogenic responses to epidermal growth factor (EGF) and platelet-derived growth factor, PDGF-AA were potentiated by 33 and 31%, respectively. We conclude that epithelium-specific adenovirus-mediated over-expression of a dominant-negative TGF-beta type II receptor completely and specifically abolished the anti-proliferative effects of both endogenous and exogenous TGF-beta. Therefore, epithelium-specific TGF-beta signaling is sufficient to negatively regulate embryonic lung-branching morphogenesis in culture. We speculate that abrogation of TGF-beta signaling stimulates lung morphogenesis by potentiating the inductive and permissive effects of other endogenous peptide growth factors such as EGF and PDGF-AA.
Adenoviridae↗
Bone mineral density and biomechanical properties of spine and femur of ovariectomized rats treated with naproxen.
Prostaglandins have been reported to mediate the effects of ovariectomy on bone loss. We studied the effect of naproxen, an inhibitor of production of prostaglandins, on ovariectomy-induced bone loss. One hundred forty female Wistar rats 4.5 months of age were divided into groups of baseline, sham operation (sham), sham treated with naproxen at 10 mg/kg per day (in food), and ovariectomy treated with naproxen or estrogen as intramuscular injection of estradiol at 0.2 mg/kg body weight per week. They were killed 3, 6, and 9 months postsurgery. Bone mineral density (BMD) of the lumbar spine (L1-4), femoral neck, midshaft, and distal metaphysis was determined using dual-energy X-ray absorptiometry (DXA) in vitro. The compressive test of the L1 vertebral body and torsional test of the left femur were performed. The right femoral neck and femoral midshaft were processed undecalcified for determining cross-sectional moments of inertia. Naproxen treatment partially prevented ovariectomy-induced loss or less gain in BMD, in a significant manner, in the femoral neck cortical area, and also in L1 compressive strength and stiffness. Estrogen fully prevented these ovariectomy-induced effects. Naproxen showed no effect on ovariectomy-induced improvement in femoral torsional strength and stiffness and cross-sectional moments of inertia. No statistically significant difference was found between naproxen-treated sham rats and untreated sham rats. The data suggest that naproxen partially prevents ovariectomy-induced osteopenia.
Absorptiometry, Photon↗
Surface activity of tear fluid in normal subjects.
PURPOSE: The stability of the precorneal tear film is commonly assessed by measurement of its break-up time. An alternative, but less studied, approach is measurement of the surface tension of tear fluid samples. The aim of this study was to develop a clinical method for measurement of the surface activity of tear fluid. METHODS & RESULTS: Tear fluid was sampled from 20 normal subjects. Surface activity of the samples was measured on a Wilhelmy balance. Maximum and minimum surface tension of tear fluid samples was 71.5+/-1.3 mN/m and 46.6+/-3.8 mN/m, respectively. Surface tension was also recorded on solutions of bovine Meibomian lipids and bovine submaxillary mucin. The area/surface tension tracings obtained from solutions of lipids and mucin were qualitatively similar to those obtained from tear fluid samples. The effects of Meibomian lipids and mucin were additive. CONCLUSION: The technique for measurement of the surface activity of tear fluid is minimally invasive and easy to use. The inter-individual differences in surface tension of tear fluid are small in normal subjects. The technique may be a useful supplement to measurement of break-up time in the evaluation of patients with dry eyes.
Adolescent↗
Thymic lymphoproliferative disease after successful correction of CD40 ligand deficiency by gene transfer in mice.
Inherited deficiency of the CD40 ligand (X-linked hyper-IgM syndrome) is characterized by failure of immunoglobulin isotype switching and severe defects of cell-mediated immunity. To test the potential for gene transfer therapy to correct this disorder, we transduced murine bone marrow or thymic cells with a retroviral vector containing the cDNA for the murine CD40 ligand (CD40L) and injected them into CD40L-/- mice. Even low-level, constitutive expression of the transgene stimulated humoral and cellular immune functions in these mice. With extended follow-up, however, 12 of 19 treated mice developed T-lymphoproliferative disorders, ranging from polyclonal increases of lymphoblasts to overt monoclonal T-lymphoblastic lymphomas that involved multiple organs. Our findings show that constitutive (rather than tightly regulated), low-level expression of CD40L can produce abnormal proliferative responses in developing T lymphocytes, apparently through aberrant interaction between CD40L+ and TCRalphabeta+CD40+ thymocytes. Current methods of gene therapy may prove inappropriate for disorders involving highly regulated genes in essential positions in proliferative cascades.
Animals↗
Carboxyl terminal of rhodopsin kinase is required for the phosphorylation of photo-activated rhodopsin.
Human rhodopsin kinase (RK) and a carboxyl terminus-truncated mutant RK lacking the last 59 amino acids (RKC) were expressed in human embryonic kidney 293 cells to investigate the role of the carboxyl terminus of RK in recognition and phosphorylation of rhodopsin. RKC, like the wild-type RK, was detected in both plasma membranes and cytosolic fractions. The C-terminal truncated rhodopsin kinase was unable to phosphorylate photo-activated rhodopsin, but possesses kinase activity similar to the wild-type RK in phosphorylation of small peptide substrate. It suggests that the truncation did not disturb the gross structures of RK catalytic domain. Our results also show that RKC failed to translocate to photo-activated rod out segments. Taken together, our study demonstrate the carboxyl terminus of RK is required for phosphorylation of photo-activated rhodopsin and strongly indicate that carboxyl-terminus of RK may be involved in interaction with photo-activated rhodopsin.
Cell Line↗
Evidence for association between polymorphisms in the promoter and coding regions of the 5-HT2A receptor gene and response to clozapine.
Clozapine is a potent atypical antipsychotic which binds to a variety of neurotransmitter receptors including serotonin (5-HT) receptors. However, the precise neurochemical site of clozapine's therapeutic action is unknown. We hypothesize that genetic variation in the neurotransmitter receptors to which the drug binds may influence clozapine response. To test this hypothesis we genotyped a novel -1438-G/A polymorphism detected in the promoter region, and a His452Tyr polymorphism described in the coding region of the 5-HT2A receptor gene in two independent samples of clozapine-treated patients including responders and non-responders. Although the strong association between these polymorphisms and clozapine response observed in the first sample (sample I) was not statistically significant in the second sample (sample II), the results in both samples were in the same direction. Homozygosity for the allele G-1438 was higher among non-responders (56% in sample I, 43% in sample II) than in responders (28% in sample I and 32% in sample II) in both samples. Similarly, the frequency of allele Tyr452 was higher in non-responders (11% in sample I, 16% in sample II) than in responders (6% in sample I and 10% in sample II). A combined analysis of both samples showed association between both polymorphisms and clozapine response. These results provide further evidence suggesting that genetic variation at 5-HT2A receptors may influence clozapine response and strengthen the candidacy of these receptors as important therapeutic targets.
Alleles↗
Interactive image-guided neuroendoscopy: development and early clinical experience.
Technical advances and pioneering surgeons have established neuroendoscopy as an accepted diagnostic and therapeutic tool. The clinical indications for endoscopy, variety of operative techniques and number of endoscopic surgeons continue to increase steadily. However, there are fundamental limits to the scope of freehand endoscopy principally governed by the need for direct vision of anatomical and pathological structures. In addition, whilst the expert neuroendoscopist is only occasionally disorientated by complex distorted anatomy, the rising number of novices are likely to be mislead relatively often. We report the integration of neuroendoscopy with an optical neuronavigation system to provide interactive image-guided neuroendoscopy. This combination both removes the constraining requirement for direct vision and provides accurate localisation to guide the surgeon during surgery. We describe the clinical application of this method to two cases where image-guided endoscopy was essential to the safe completion of the procedure.
Adult↗
Tamoxifen downregulates TGF-beta production in keloid fibroblasts.
Keloids occur only in humans and are characterized by fibroblast overproduction of collagen types I and III. Keloid fibroblasts have been shown to make elevated levels of transforming growth factor beta (TGF-beta), a growth factor known to promote extracellular matrix production and fibrosis. Thus, the pathophysiology underlying keloid formation may be driven by the biological activity of TGF-beta. Tamoxifen, a synthetic, nonsteroidal antiestrogen has been shown to inhibit keloid fibroblast proliferation and decrease collagen production. The purpose of this study was to determine if a mechanism by which tamoxifen decreases keloid collagen production is through a downregulation of TGF-beta. Through a luciferase TGF-beta bioassay we found that 4 microM of tamoxifen generated a 49% reduction in total TGF-beta activity and 8 microM generated an 85% reduction compared with controls. Thus we propose that one of the mechanisms by which tamoxifen decreases keloid fibroblast collagen synthesis is by decreasing TGF-beta production.
Cell Culture Techniques↗
Induction of Arabidopsis tryptophan pathway enzymes and camalexin by amino acid starvation, oxidative stress, and an abiotic elicitor.
The tryptophan (Trp) biosynthetic pathway leads to the production of many secondary metabolites with diverse functions, and its regulation is predicted to respond to the needs for both protein synthesis and secondary metabolism. We have tested the response of the Trp pathway enzymes and three other amino acid biosynthetic enzymes to starvation for aromatic amino acids, branched-chain amino acids, or methionine. The Trp pathway enzymes and cytosolic glutamine synthetase were induced under all of the amino acid starvation test conditions, whereas methionine synthase and acetolactate synthase were not. The mRNAs for two stress-inducible enzymes unrelated to amino acid biosynthesis and accumulation of the indolic phytoalexin camalexin were also induced by amino acid starvation. These results suggest that regulation of the Trp pathway enzymes under amino acid deprivation conditions is largely a stress response to allow for increased biosynthesis of secondary metabolites. Consistent with this hypothesis, treatments with the oxidative stress-inducing herbicide acifluorfen and the abiotic elicitor alpha-amino butyric acid induced responses similar to those induced by the amino acid starvation treatments. The role of salicylic acid in herbicide-mediated Trp and camalexin induction was investigated.
5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
Radiologically placed hepatic artery catheter allows selection of patients with high-volume liver metastases for regional chemotherapy.
Regional chemotherapy has achieved high response rates in hepatic metastases from colorectal cancer and has been shown to improve survival significantly. The present paper reports the use of pre-operative regional therapy to establish marker response as a means of selection of patients for surgery. Fourteen patients underwent radiologically placed hepatic artery catheter (HAC) for chemotherapy. In the 11 patients with carcino-embryonic antigen (CEA) fall the patient proceeded to open surgical placement of HAC. The predictive effect of CEA fall following radiological HAC was good. Non-responding patients are clearly spared the discomfort and inconvenience and costs of an unnecessary operation.
Adult↗
N-Methyl-D-aspartate attenuates opioid receptor-mediated G protein activation and this process involves protein kinase C.
The effects of N-methyl-D-aspartate (NMDA) on opioid receptor-mediated G protein activation were explored in neuroblastoma X glioma hybrid (NG108-15) cells. Treatment of the cells with NMDA resulted in a remarkable attenuation of [35S]guanosine-5'-O-(3-thio)triphosphate binding stimulated by [D-Pen2,D-Pen5]-enkephalin (DPDPE), a delta-opioid receptor agonist. The effects of NMDA were dose and time dependent with an IC50 value of 5 nM and could be blocked by NMDA receptor antagonists. After NMDA treatment, the DPDPE dose-response curve shifted to the right (EC50 value increased approximately 7-fold, from 6 to 40 nM), and the maximal response induced by DPDPE was reduced by approximately 60%. The effects of NMDA were reversible, and the DPDPE response could recover within 60 min. The functional responses of delta-, mu-, and kappa-opioid receptors in primarily cultured neurons also were attenuated significantly by NMDA treatment. The inhibitory effects of NMDA on opioid receptor-mediated G protein activation could be blocked by coadministration of the protein kinase C (PKC) inhibitors or by elimination of the extracellular Ca2+. Correspondingly, NMDA treatment of NG108 cells significantly elevated cellular PKC activity and stimulated Gialpha2 phosphorylation. Transient transfection into NG108-15 cells of the wild-type Gialpha2 and a mutated Gialpha2 (Ser144Ala) resulted in a 2-fold increase in DPDPE-stimulated G protein activation. The DPDPE responses were greatly inhibited by NMDA treatment in the wild-type Gialpha2-transfected cells but much less affected in the mutant Gialpha2-transfected cells. In summary, NMDA attenuates opioid receptor/G protein coupling, and this process requires activation of PKC.
Animals↗