A survey of work done by the China family planning association.
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Asia↗
Biomedical subjects
W Guo
Publications and source records attributed to W Guo.
Removal of endotoxin from aqueous solutions by affinity membrane.
Endotoxin was removed by affinity membranes with histidine immobilized as affinity ligand. Macropore cellulose membrane was prepared from filter paper by alkaline treatment and chemical crosslinking, and was used as matrix for the immobilization of affinity ligand. The matrix membrane was derived by hexamethylenediamine and activated by glutaraldehyde before histidine was immobilized. Membrane cartridges containing 40 or 80 sheets of affinity membrane were also prepared, which can be used to remove pyrogen from aqueous solutions. Using a cartridge with 40 sheets of affinity membrane, the endotoxin content in solution can be reduced to a minimum of 0.12 EU/mL.
Chromatography, Affinity↗
Determination of cis and trans isomers of tramadol hydrochloride by capillary zone electrophoresis.
Cis and trans isomers of tramadol hydrochloride were separated by capillary zone electrophoresis (CZE) in a fused-silica capillary with 40 mmol/L of borate as a carrier. The sample concentration-peak area plots were straight lines in the range 10-250 micrograms/mL for both isomers. Based on the electropherogram, the relationship between the structure of the two isomers and the elution order has been discussed. It is considered that the trans isomer has larger hydrodynamic radius than the cis isomer and lower electric charge density. The elution order can be predicted only according to the direction of electrophoresis and electroendo-osmotic flow. The technique was successfully applied to the industrial production and the research for utilization of industrial waste material.
Electrophoresis, Capillary↗
Membrane affinity chromatography used for the separation of trypsin inhibitor.
Polysulphone (PS) was chemically modified by acrylation-amination and by chloromethylation-amination, respectively. An ultrafiltration membrane of chemically modified polysulphone (CMPS) was prepared by the phase inversion method. Trypsin was then covalently bonded onto the CMPS membrane by diazotization. The activity of immobilized trypsin reaches up to 10200 U/g; 15 mg trypsin was immobilized on 1 g CMPS membrane. Separation of soybean trypsin inhibitor was carried out on the affinity membrane, yielding 6.5 mg pure trypsin inhibitor in one run. The enzyme membrane has good activity and stability.
Chromatography, Affinity↗
A new matrix for affinity chromatography and its application in the separation of a human monoclonal antibody.
A method for the preparation of a p-aminobenzene sulphonyl ethyl containing crosslinked Sepharose 4B (ABSE-Sepharose 4B-CL) is described, trypsin, bovine serum albumin (BSA) and concanavalin A (Con A) were immobilized onto this matrix by diazotization. Conditions for the coupling reaction were investigated. The activity of immobilized trypsin reached 1.4 x 10(4) U/g, and 25 mg BSA can be coupled onto 1 g ABSE-Sepharose 4B-CL under the optimal conditions. An affinity medium with immobilized Con A as ligand was prepared by this method, and was used in the separation of a human monoclonal antibody.
Antibodies, Monoclonal↗
Human ARX gene: genomic characterization and expression.
Arx is a homeobox-containing gene with a high degree of sequence similarity between mouse and zebrafish. Arx is expressed in the forebrain and floor plate of the developing central nervous systems of these vertebrates and in the presumptive cortex of fetal mice. Our goal was to identify genes in Xp22.1-p21.3 involved in human neuronal development. Our in silico search for candidate genes noted that annotation of a human Xp22 PAC (RPCI1-258N20) sequence (GenBank Accession No. AC002504) identified putative exons consistent with an Arx homologue in Xp22. Northern blot analysis showed that a 3.3kb human ARX transcript was expressed at high levels in fetal brain. A 5.9kb transcript was expressed in adult heart, skeletal muscle, and liver with very faint expression in other adult tissues, including brain. In situ hybridization of ARX in human fetal brain sections at various developmental stages showed the highest expression in neuronal precursors in the germinal matrix of the ganglionic eminence and in the ventricular zone of the telencephalon. Expression was also observed in the hippocampus, cingulate, subventricular zone, cortical plate, caudate nucleus, and putamen. The expression pattern suggests that ARX is involved in the differentiation and maintenance of specific neuronal cell types in the human central nervous system. We also mapped the murine Arx gene to the mouse genome using a mouse/hamster radiation hybrid panel and showed that Arx and ARX are orthologues. Therefore, investigations in model vertebrates may provide insight into the role of ARX in development. The recent identification of ARX mutations in patients with various forms of mental retardation make such studies in model organisms even more compelling.
Amino Acid Sequence↗
Efficient gene transfer using reversibly cross-linked low molecular weight polyethylenimine.
Polyethylenimine (PEI) is a polycation with potential application as a nonviral vector for gene delivery. Here we show that after conjugation with homobifunctional amine reactive reducible cross-linking reagents, low molecular weight polyethylenimine efficiently mediates in vitro gene delivery to Chinese hamster ovary (CHO) cells. Two cross-linking reagents, dithiobis(succinimidylpropionate) (DSP) and dimethyl.3,3'-dithiobispropionimidate*2HCl (DTBP), were utilized based on their reactivity and chemical properties. Both reagents react with primary amines to form reducible cross-links; however, unlike DSP, the DTBP cross-linker maintains net polymer charge through amidine bond formation. PEI with a reported weight-average molecular weight (M(w)) of 800 Da was reacted with either DSP or DTBP at PEI primary amine:cross-link reactive group ratios of 1:1 and 2:1. The transfection efficiencies of the resulting cross-linked products were evaluated in CHO cells using a luciferase reporter gene under a cytomegalovirus (CMV) promoter. Our results show that cross-linked polymers mediate variable levels of transfection depending on the cross-linking reagent, the extent of conjugation, and the N/P ratio. In general, we found conjugate size to be proportional to gene transfer efficiency. Using gel retardation analysis, we also evaluate the capacity of the cross-linked polymers to condense plasmid DNA before and after reduction with 45 mM dithiothreitol (DTT). DTT mediated reduction of intra-cross-link disulfide bonds and inhibited condensation of DNA by conjugates cross-linked with DSP at a ratio of 1:1, but had little effect on the remaining polymers. Analogous intracellular reduction of transfection complexes by reduced glutathione could facilitate uncoupling of PEI from DNA to enhance gene expression.
Animals↗
Diet and blood nutrient correlations with ischemic heart, hypertensive heart, and stroke mortality in China.
Though major differences exist in subcategory mortality levels, cardiovascular disease remains a leading cause of death among both Asian Chinese and Westerners. This paper examines the possible relationship between cardiovascular mortality and biochemical, diet and lifestyle factors based on two surveys in China. Statistically significant associations indicate five variables negatively correlated: molybdenum, oleic acid, liquor consumption (males), legumes, and age at first pregnancy with ischemic heart disease; molybdenum, oleic acid (females) and age at first pregnancy with hypertensive heart disease; and legumes and age at first pregnancy with stroke. Five variables were positively correlated: triglycerides and herpes antibodies with ischemic heart disease; salt and phosphorus (females) with hypertensive heart disease; and only albumin (males) with stroke. Some findings confirm those observed in the West (salt, triglycerides, herpes, legumes, oleic acid, and liquor), but molybdenum and age at first pregnancy have not been emphasized previously. Still others significant in the West have not been observed here, such as cholesterol and smoking.
Adolescent↗
A study on tea aroma formation mechanism: alcoholic aroma precursor amounts and glycosidase activity in parts of the tea plant.
We have shown in molecular basis that alcoholic tea aroma is mainly formed by endogenous enzymatic hydrolysis of glycosidic aroma precursors during manufacturing. Amounts of alcoholic aroma precursor and glycosidase activity in each part of the tea shoot (Camellia sinensis var. sinensis cv Yabukita and a hybrid of var. assamica & var. sinensis cv Izumi) were indirectly measured by means of a crude enzyme assay. The aroma precursors were abundant in young leaves and decreased as the leaf aged. Glycosidase activity also decreased as leaves aged, but was high in stems.
Carbohydrate Conformation↗
Role of topical phospholipids in the prophylaxis of silicone elastomer-associated infection in the abdominal cavity.
The present study evaluated the influence of phospholipids (phosphatidyl choline and phosphatidyl inositol) on the prevention of abdominal biomaterial-associated infection. Phospholipid-impregnated silicone elastomer (SE) fragments were either intraperitoneally implanted in rats or immersed in serum for 0, 4, and 14 days, and 3 x 10(9) cfu of 3H-labeled, live Escherichia coli were added in the peritoneal cavity or in vitro incubation medium. Three hours after incubation, the adherence of bacteria significantly decreased to phospholipid-impregnated SE fragments, which had been immersed/implanted for 0 and 4 days. However, the number of adhering bacteria did not differ between the impregnated and unimpregnated SE fragments after 14 days of immersion/implantation. A significantly lower number of adhering bacteria was noted on all unimpregnated SE fragments when phospholipid was supplemented in the peritoneal cavity or in vivo medium, compared with fragments with no supplement. The rate of bacterial DNA synthesis decreased significantly after incubation with phospholipid 2 h or more. Phospholipids did not further influence peritoneal morphology. Thus topical administration of phospholipids by impregnation to the surface of SE fragments or supplement in the incubation medium prevented bacterial adherence onto the SE fragments. This implies that the use of phospholipids might be a mode of preventing biomaterial-associated infections.
Administration, Topical↗
Effects of a water-soluble ethylhydroxyethyl cellulose on gut physiology, bacteriology, and bacterial translocation in acute liver failure.
Bacterial infection and bacteremia are common complications in patients with acute liver failure. Bacterial translocation from the gut has been suggested to be a major cause of bacterial infections in experimental acute liver failure. In the present study, a water-soluble ethylhydroxyethyl cellulose (EHEC) was administered orally 1 and 24 hours prior to 90% hepatectomy in the rat in order to prevent bacterial translocation in experimental acute liver failure induced by subtotal liver resection in the rat. Ninety percent hepatectomy alone resulted in 80 to 100% translocation to mesenteric lymph nodes or blood 2 and 4 hours after operation. There was no translocation in rats undergoing sham operation or 90% hepatectomy with EHEC administration prior to operation (p < .01). Bacterial overgrowth, increased bacterial adherence onto the intestinal surface, and diminished intestinal and mucosal mass were also observed in animals with subtotal liver resection, but not in those administered EHEC. A delayed 2-hour intestinal transit time occurred in both groups receiving subtotal liver resection, with or without oral EHEC. EHEC inhibited bacterial growth and DNA synthesis and altered bacterial surface properties after 1-hour incubation with bacteria in vitro, an interaction that was not further influenced by time. These results imply that EHEC may alter enterobacterial capacities of metabolism, proliferation, and invasion by effects on the bacterial surface. Furthermore, EHEC seems to possess a trophic action on the intestine, though without enhancing the intestinal motility.
Acute Disease↗
Immortalization of human oral keratinocytes is associated with elevation of telomerase activity and shortening of telomere length.
Telomerase is a ribonucleoprotein complex that synthesizes TTAGGG repeat sequences at the ends of mammalian chromosomes. Its activity is found in most cancer cells and few rare normal somatic cells. To investigate whether telomerase activity and telomere length of normal human oral keratinocytes (NHOK) are altered by human papillomaviruses (HPV), we transfected primary NHOK with type 16 HPV (HPV-16) genome and determined the activity of telomerase. HPV transfection extended the life span of NHOK and eventually induced immortalization of cells. Moderate telomerase activity was consistently observed in rapidly proliferating NHOK, and activity was not changed in HPV-16 transfected cells with extended life span. However, the activity was sharply increased when cells passed the crisis stage. Telomere length, which remained constant at approximately 6.8 kb during serial passages of NHOK, progressively shortened in HPV DNA transfected cells during the period of extended life span and continued until crisis, after which it stabilized at approximately 5 kb. These results demonstrate that immortalization of NHOK with HPV-16 DNA is associated with the activation of telomerase.
Cell Division↗
HPV-16 E6 oncoprotein induces mutations via p53-dependent and -independent pathways.
The E6 oncoprotein of human papillomaviruses (HPV) promotes oncogenesis by inactivating tumor suppressor protein p53 i. e. it binds to and enhances the degradation of p53. To study whether inactivation of p53 is solely responsible for E6-induced oncogenesis, we constructed several plasmid vectors expressing wild-type (wt) or mutant (mt) E6 proteins. RKO cells that express wt p53 were stably transfected with these plasmids and challenged with DNA damaging agents. The level of p53 was significantly increased by DNA damaging agents in control cells and cells transfected with plasmids expressing mt E6 that do not bind to p53. As expected, p53 did not increase in cells transfected with plasmids expressing mt E6 that do bind to p53. To investigate the oncogenic effect of these various E6 proteins, we determined the mutation frequency of the hprt locus in control cells and cells expressing different E6 proteins. We found that cells expressing wt E6 and mt E6 (capable or incapable of binding to p53) showed notable increases in the mutation frequency at hprt locus compared with that of control cells. The elevation of mutation frequency in cells expressing mt E6 was similar to that in cells expressing wt E6. These data indicate that E6-induced mutagenicity is induced not only via p53 inactivation, but also via p53-independent pathways.
Colorectal Neoplasms↗