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X Lei

Publications and source records attributed to X Lei.

43 records · Page 3Linked to original sources
PubMed1993

Organelle-specific phosphorylation. Identification of unique membrane phosphoproteins of the endoplasmic reticulum and endosomal apparatus.

Highly purified endoplasmic reticulum fractions from rat liver and dog pancreas harbor membrane-associated kinases that phosphorylate integral membrane proteins of 90, 56, 35, and 15 kDa with [gamma-32P]GTP and of 90, 56, and 35 kDa with [gamma-32P]ATP. Of these, only the 35-kDa phosphoprotein was N-glycosylated. Screening of Golgi fractions, endosomes, plasma membranes, lysosomes, and mitochondria revealed phosphoproteins unique to each organelle. In particular, endosomes were found to harbor a 48-kDa extrinsic membrane protein and two or more integral membrane phosphoproteins of 30-35 kDa. None of these were N-glycosylated as judged by their insensitivity to digestion by N-glycosidase F and a lack of binding to concanavalin A or wheat germ agglutinin. Since the 30-35 kDa membrane phosphoproteins present in Golgi-free endosomal fractions were not detected in endosome-free, highly purified Golgi fractions and were found exclusively in horseradish peroxidase-containing endosomes as determined by the diaminobenzidine shift protocol, then these membrane phosphoproteins are unique to endosomes. Since membrane phosphoproteins unique to the endoplasmic reticulum have been shown to have important functional significance in calcium binding and as a membrane chaperone(s) (Wada, I., Rindress, D., Cameron, P.H., Ou, W.-J., Doherty, J.-J., II, Louvard, D., Bell, A.W., Dignard, D., Thomas, D.Y., and Bergeron, J.J.M. (1991) J. Biol. Chem. 266, 19599-19610; Ahluwalia, N., Bergeron, J.J.M., Wada, I., Degen, E., and Williams, D.B. (1992) J. Biol. Chem. 267, 10914-10918), then the unique endosomal phosphoproteins may serve equally important functions in addition to serving as novel markers for the organelle.

Animals↗
PubMed1993

Supplemental microbial phytase improves bioavailability of dietary zinc to weanling pigs.

Two experiments were conducted to determine the effects of supplemental microbial phytase on utilization of dietary zinc by weanling pigs. Experiment 1 was a 2 x 3 factorial arrangement of treatments with 24 pigs for 4 wk. Two levels of phytase activity (0 and 1350 units/g) and three levels of zinc (0, 30 and 60 mg/kg as ZnSO4.7H2O) were added to a corn-soybean meal basal diet. Weekly measures included growth performance, plasma alkaline phosphatase activity and plasma mineral concentrations. In Experiment 2, mineral balances were determined in 12 pigs fed the basal diet or the diet with added zinc (30 mg/kg) or phytase (1350 units/g). The results indicated that either supplemental phytase or supplemental zinc increased plasma alkaline phosphatase activity and plasma zinc concentrations, but these increases were not additive. Supplemental phytase decreased plasma alkaline phosphatase activity in pigs supplemented with zinc. Supplemental phytase also significantly enhanced weight gain, feed intake, gain:feed ratio, plasma concentrations of inorganic phosphorus, and retention of phosphorus and calcium. Neither supplemental phytase nor zinc affected zinc retention. Supplementing corn-soybean meal diets with microbial phytase at 1350 units/g feed improves bioavailability of zinc as well as of phytate phosphorus to weanling pigs.

6-Phytase↗
PubMed1992

Prevention of tissue calcification on bioprosthetic heart valve by using epoxy compounds: a study of calcification tests in vitro and in vivo.

Calcification is the principal cause of the clinical failures of the bioprosthetic heart valves fabricated from glutaraldehyde pretreated porcine aortic valves or bovine pericardium. In this paper, we compared the calcification on various types of bovine pericardiums pretreated with two hydrophilic epoxy compounds adding GA post-treatment (EP 1 and EP 2), glutaraldehyde (GA)- and nontreated pericardium (Fresh), respectively, by in vitro and in vivo tests. Significant decrease of calcification was found by pretreatment with both epoxy compounds rather than with glutaraldehyde: 0.250 +/- 0.001 (Fresh), 0.276 +/- 0.058 (EP 1), 0.302 +/- 0.071 (EP 2), and 0.478 +/- 0.172 (GA) micrograms (Ca)/mg (dried tissue), respectively, after 20 days dipping in a simulating serum solution in vitro; 115.13 +/- 60.11 (Fresh), 129.84 +/- 51.08 (EP 1), 167.39 +/- 20.81 (EP 2), and 205.19 +/- 16.86 (GA) micrograms/mg, respectively, after 3 months subcutaneous implantation in rabbits. The in vitro method for evaluating calcification designed by us gave the similar order among four samples with that obtained by in vivo test. Because the bovine pericardium pretreated with the epoxy compounds adding GA post-treatment possesses the greater tenacity than that pretreated only with epoxy compounds or GA, meanwhile the calcification is also significantly decreased with this pretreatment, it may be expected that the bovine pericardium with this pretreatment will have the greater anticalcification and durability in dynamic stress.

Animals↗
PubMed1992

Haemocompatibility of polymer having phospholipid polar groups evaluated by monoclonal antibody method.

The haemocompatibility of a polymer having the phospholipid polar group, poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate(BMA)), was evaluated by a monoclonal antibody SZ-21 (directing specifically against the membrane glycoprotein complex IIIa of human platelet) radioimmunoassay method. The study showed that poly(MPC-co-BMA) possessed better haemocompatibility than segmented polyurethane (SPEU). Radioactivity of platelets adhered (counts per min/cm) on a polyethylene (PE) tube coated with poly(MPC-co-BMA) was 19.51 +/- 5.58, with albumin; 20.05 +/- 7.29, with SPEU having sulphonated group; 76.10 +/- 18.9, with SPEU; 287.0 +/- 95.0, PE treated by plasma irradiation; 2091 +/- 261, and original PE was 1772 +/- 116. The results were further certified by scanning electron microscopic observations.

Antibodies, Monoclonal↗
PubMed1991

Targeting of gene expression to skeletal and cardiac muscle of trangenic animals.

The tissue restricted and developmental potentiation of transcription by chicken alpha-skeletal actin promoter regions fused to the reporter gene chloramphenicol acetyl transferase (CAT) were characterized in transgenic mice. Six of eight expressing transgenic mouse lines containing the chicken alpha-skeletal actin promoter fused to CAT resulted in preferential transgene transcription in skeletal muscle tissue, similar to the endogenous mouse alpha-skeletal actin gene. Two of the eight lines departed from the preferred pattern of skeletal muscle expression with primary expression of the transgene in the heart, a tissue containing primarily cardiac actin isoforms. Developmentally, a transition from embryonic heart to fetal and neonatal skeletal muscle expression was produced by the transgene promoter, a pattern of regulation similar to that of the endogenous alpha-skeletal actin gene. Instances of departure of transgene expression from the endogenous gene implied the existance of higher order muscle gene regulatory mechanisms.

Actins↗
PubMedDate not supplied

AutoPap system performance in screening for low prevalence and small cell abnormalities.

OBJECTIVE: To summarize the design principles of the AutoPap System evaluation score by evaluating slides having a low prevalence of abnormal cells and small cell abnormalities and assessing the evaluation score as a diagnostic tool. STUDY DESIGN: Data from two clinical studies conducted using the AutoPap System and data obtained from the evaluation score training slides were analyzed to demonstrate the effectiveness of the evaluation score. The clinical studies included a prospective, intended-use study involving approximately 13,000 slides and a comprehensive sensitivity study using approximately 1,200 slides from five laboratories. The evaluation score training set consisted of 4,174 slides from 10 laboratories. RESULTS: The robust design of the AutoPap evaluation score was demonstrated by similar detection capabilities and sensitivities to slides having either a low or high prevalence of abnormal cells. No significant difference in performance was detected between the small cell slides and the comparison groups of carcinoma in situ and invasive squamous carcinoma having normal-sized abnormal cells. In addition, the evaluation scores corresponded well to the diagnostic severity of the slides.

Algorithms↗