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C B Wu

Publications and source records attributed to C B Wu.

14 recordsLinked to original sources
PubMed2000

[Plant regeneration from protoplast culture in flax (Linum usitatissimum)].

Shoot protoplasts of four fiber flax (Linum usitatissimum) varieties (7309, 948, Belinka and Viking) were isolated and cultured. The optimal condition for higher protoplast yield 1.8 x 10(6)/gFW and activity 85.5% (c.v. 948) were from 10 day old seedings. Culture in V-KM Agroase-island medium led to first divisions after 3 days (c. v. 948), and after twenty days with an efficiency of 36% of divided cells and 5.2% in plating efficiency. Plant regeneration was obtained in 7309 and Belinka on agar media B5-2, MS3 containing 0.6 mg/L 6-BA and 0.1 mg/L NAA. Roots and leaves regeneration were observed in Viking and 948 respectively.

Cell Division↗
PubMed1997

Phosphorylation of the proteins of the extracellular matrix of mineralized tissues by casein kinase-like activity.

The extracellular matrix of the connective tissue contains non-collagenous proteins (NCP) which are acidic in character. The NCP of mineralizing systems (bone, dentin) differ from those of the non-mineralizing systems (skin, tendon) in that the mineralized tissue NCP are frequently phosphorylated. The phosphorylated proteins have been implicated in various aspects of the mineralization process. Thus, it is of interest to consider the mechanism and regulation of phosphorylation of the major matrix NCP. The majority of the phosphorylation takes place at Ser or Thr residues embedded within acidic sequences, and therefore are targets for casein kinase I (CK1) or casein kinase II (CK2)-like kinases. CK1 and CK2 are distantly related members of the protein kinase family. They are ubiquitous, constitutively active, second-messenger-independent kinases. CK1 is found in a variety of isoforms, all homologous to the alpha-subunit of the protein kinase family. It acts as a monomer. The active form of CK2 is a tetrameric holoenzyme, with 2 alpha catalytic subunits and 2 beta regulatory subunits. The CK2 alpha has activity alone, but the holoenzyme is four- to five-fold that activity. CK2 can use either ATP or GTP as the phosphate donor, but CK1 can use only ATP. The CK2 activity which phosphorylates the mineralized tissue NCP appears to be localized to membrane-associated cell fractions, and is present in the endoplasmic reticulum and Golgi compartments in osteoblasts, where phosphorylation of the secreted proteins appears to take place as co- and post-translational processes. Data indicate that both alpha and beta subunits of the membrane-associated CK2 are isoforms of the cytosolic CK2 in the same cells. The CK1 has not been specifically localized. Studies of dephosphorylated NCP such as phosphophoryn (PP) have shown that CK1 will not phosphorylate dephosphorylated dPP unless prior phosphorylation with CK2 has been carried out. In turn, CK2 activity may be initiated only after an initial phosphorylation of one of the messenger-dependent kinases. Thus, the phosphorylation reactions in mineralized tissues may be a tightly regulated hierarchical or sequential cascade of intracellular phosphorylation events.

Adenosine Triphosphate↗
PubMed1996

Characterization and partial purification of microsomal casein kinase II from osteoblast-like cells: an enzyme that phosphorylates osteopontin and phosphophoryn.

Microsomal casein kinase II (mCKII) is a membrane-bound enzyme present in the microsomal fractions of ROS 17/2.8 osteoblast-like cells. It phosphorylates acidic matrix phosphoproteins such as phosphophoryn and osteopontin. Addition of 1.0% Nonidet P-40 facilitates extraction of the optimum amount of detergent-solubilized and -activated enzyme from microsomal fractions. mCKII was partially purified over 3000-fold by sequential chromatography over DEAE-cellulose and heparin-agarose. SDS-polyacrylamide gels, showed that mCKII contained 43 kDa and 31 kDa polypeptides, corresponding to the alpha- and beta-subunits of the enzyme, respectively. The alpha subunit was identified by anti-CKII antiserum and the beta subunit, by its ability to undergo autophosphorylation. The enzyme was inhibited by 50% with 0.4 micrograms/ml heparin and stimulated by 100% with 1.0 mM spermine when casein was used as a substrate. The phosphorylation of phosphophoryn was reduced to 50% by 0.8 micrograms/ml heparin, but was increased to 2-2.5 fold by 5 to 15 mM spermine, which may be due to substrate-directed effects. Kinetic analysis showed that the apparent Km values for phosphophoryn (0.39 microM) and for osteopontin (2.1 microM) were lower than that for casein (21.3 microM). Vmax values of phosphophoryn and osteopontin were 2.2-fold and 4.6-fold higher than that of casein. Using the ratio Vmax/Km as a measure of kinetic specificity, osteopontin and phosphophoryn appear to be the more specific substrates than casein for mCKII. Thus, both proteins can be considered as physiological substrates for mCKII.

Animals↗
PubMed1995

Microsomal casein kinase II in endoplasmic reticulum- and Golgi apparatus-rich fractions of ROS 17/2.8 osteoblast-like cells: an enzyme that modifies osteopontin.

Osteopontin is an acidic phosphoprotein containing casein kinase II (CKII) phosphorylatable sites and an acidic amino acid cluster. The metabolically 32P-labelings of both serines and threonines in vitro in osteopontin immunoprecipitated from rat osteoblast-like ROS 17/2.8 cells may suggest that casein kinase II catalyzes this modification. The enzyme occurs in microsomal fractions of rat osteoblast-like ROS 17/2.8 cells. Subcellular fractions containing endoplasmic reticulum and Golgi apparatus were isolated by differential centrifugation and were identified according to their ultrastructures and the presence of marker enzymes such as glucose-6-phosphatase and thiamine pyrophosphatase, respectively. both fractions phosphorylated the partially dephosphorylated osteopontin and the specific substrate peptide RRREEETEEE. Endoplasmic reticulum-catalyzed peptide phosphorylation was 2.7 times lower than that of Golgi although both endoplasmic reticulum- and Golgi-catalyzed peptide reactions were 50% inhibited by 20 and 100 ng/ml heparin, respectively. Western blot analysis revealed that both fractions contained osteopontin and microsomal CKII. Furthermore, microsomal CKII was immunogold-labeled in endoplasmic reticulum and Golgi apparatus. Heparin inhibition and utilization of [gamma-32P]GTP as a phosphate donor by both fractions confirmed their capacity to phosphorylate osteopontin. The results suggest that microsomal CKII modifies the acidic matrix proteins during transportation. These matrix phosphoproteins may participate in the mineralization process of hard tissues.

Amino Acid Sequence↗
PubMed1995

Autosomal dominant, familial spastic paraplegia, type I: clinical and genetic analysis of a large North American family.

"Familial spastic paraplegia" (FSP) refers to clinically and genetically diverse syndromes characterized by insidiously progressive lower extremity spasticity. We evaluated 126 members of a large kindred, including 31 affected subjects, in which FSP was transmitted as a stereotyped, autosomal dominant disorder that showed complete genetic penetrance. Affected subjects developed insidiously progressive gait disturbance between ages 12 and thirty-five. Neurologic examination revealed hyperreflexia and spasticity in the lower extremities, weakness of hip flexion and ankle dorsiflexion, extensor plantar response, diminished vibratory sense in the feet, and pes cavus. Using genetic linkage analysis, we excluded the FSP1 locus on chromosome 14q11.2 as the disease locus in this family. We present the clinical and genetic features of FSP type I, including the age-adjusted risk of developing the disorder in this family.

Adolescent↗
PubMed1994

[Studies on magnetic responsiveness and renal embolization with magnetic microspheres in dogs].

The responsiveness and transcatheter embolization with magnetic gelatin microspheres (MG-ms) in dog kidney were reported. In experiments with magnet using a constant flow apparatus such as roller pump, the percent retention was determined by counting the carrier retained by the magnetic field and divided by the total starting counts. Factors influencing the percent retention of MG-ms include: velocity of medium flow, magnetic field intensity, alpha-Fe2O3 content in the MG-ms, viscosity of the medium and so on. Transcatheter embolization with MG-ms (10-30 microns) was performed under external magnet control in dog kidney. The result of angiogram and histological section showed that the MG-ms were in the arteries, arterioles, and glomerular capillaries with no adverse reactions. The embolized effect with magnet field was more prominent than the group without magnet field. These results show that the MG-ms is a promising embolic agent for treatment of renal cancer under external magnet control.

Animals↗
PubMed1993

[Studies on pharmacologic disposition of adriamycin in dog after hepatic arterial embolization with adriamycin carboxymethyl-dextran-microspheres].

The ion exchange adriamycin carboxymethyl-dextran-microspheres (AD-CM-DMS) was chosen as a model preparation. Pharmacokinetics, targeting and embolization effects of the microspheres were studies after hepatic arterial embolization in vivo in dogs. After hepatic arterial infusion, the concentrations of ADM in peripheral vein blood and hepatic tissue were determined by HPLC. The peak concentrations were (0.558 micrograms/ml for AD-CM-DMS and 1.013 micrograms/ml for ADM solution. T1/2 (alpha), T1/2 (beta) and MRT of AD-CM-DMS were respectively 2.82, 3.19 and 1.28 times as much as those of ADM solution. At the target site, the tissue concentrations of AD-CM-DMS were respectively 8.0 and 9.1 times those of ADM solution. The dynamic vessel angiography revealed no external and internal collaterals and no complete degradation of AD-CM-DMS after sixteen weeks was observed. These results suggest that AD-CM-DMS are useful as embolic agent for the treatment of hepatic cancer. It could facilitate intensive chemotherapy with minimum systematic side effect.

Animals↗
PubMed1993

[Studies on distribution of magnetic gelatin microspheres in rabbits].

In this report, the technique of labelling MG-ms with 99mTc as pertechnetate in the presence of a reducing agent such as SnCl2 was described. The distribution of intravenously injected 99mTc-labelled MG-ms in rabbits at different intervals of magnetic field applied and different magnetic field intensity was investigated by using an externally applied magnetic field and measuring the radioactivity at the rabbit head and other organs. When magnet was used, the radioactivity in the head, target site, was 15 times more than that when magnet was not used. At the same time, the radioactivity of the lung was 5 times less than when magnet was not used. The newly designed magnetic field equipment was presented.

Animals↗
PubMed1992

The in vitro phosphorylation of the native rat incisor dentin phosphophoryns.

Phosphophoryns are the major non-collagenous proteins of the mineralized matrix of rat incisor dentin. Nearly half the phosphophoryn residues are serines, and 85-90% of these are phosphorylated. Since phosphorylation may be important for phosphophoryn function, it was of interest to identify the kinase(s) responsible for catalyzing their phosphophorylation. Rat osteosarcoma (ROS) 17/2.8 osteoblast-like cells were selected as the enzyme source. Native rat incisor phosphophoryns (RIPP-I, II, III) were not substrates for any of the ROS 17/2.8 messenger-dependent kinases but were phosphorylated by membrane-associated endogenous messenger-independent kinases. These were resolved chromatographically and identified as casein kinase (CK) I and II by elution properties and immunoblotting with a CKII antibody. The CKI preferentially used RIPP-III as substrate, while CKII preferred RIPP-I and II. Heparin at 100 and 500 ng/assay and NaCl at 0.25-0.4 M inhibited phosphorylation of the RIPP by CKI and CKII in parallel. At 10 mM spermine, phosphorylation of RIPP-I and II by CKII, and of RIPP-III by CKI were inhibited, but phosphorylation of RIPP-III by CKII was enhanced. Purified sea star oocyte CKII demonstrated the same substrate specificity and spermine concentration shift as the ROS 17/2.8 CKII. These data show that osteoblast-like cells are a rich source of membrane-bound CKI and CKII activity. The different patterns of phosphorylation of RIPP-I, II, and III further show that they are distinct synthetic products of the odontoblast.

Adenosine Triphosphate↗
PubMed1990

Phosphorylation of extracellular bone and dentine matrix proteins.

Phosphoproteins appear to be involved in several ways in the regulation of the orderly deposition and crystal growth of mineral within the performed collagenous matrix of bone and dentine. The phosphorylation of these proteins is not yet understood. Potential protein kinases were extracted from an osteoblast-like cell line, ROS 17/2.8. The ROS 17/2.8 line was shown to produce a full complement of known kinases. However, neither bone phosphoproteins (BPP) nor dentine phosphophoryn (DPP) could be phosphorylated by the messenger dependent kinases. DPP and dephosphorylated BPP (dBPP) were substrates for a unique messenger independent kinase distinct from casein kinase II, and dDPP was a still better substrate. Thus, BPP and DPP are phosphorylated by a unique kinase or set of kinases which are messenger independent and have very specific substrate sequence requirements.

Bone and Bones↗
PubMed1989

Characterization of the molecular weights of bovine molar, rat incisor, and other phosphophoryns.

The phosphophoryns show anomalous behavior in solution, and are easily degraded during extraction. They appear in varied forms in the teeth of different species and differ in the teeth of the same species in a developmental and age dependent fashion. This set of properties has made the characterization of the phosphophoryns by biochemical means a difficult and controversial subject. Bovine molar phosphophoryn, bPP, has been characterized in detail by a variety of physical methods, and then compared with the PP from other species by DEAE-HPLC, gel electrophoresis, and immunological cross reactivity. The possible existence of a proPP biosynthetic precursor has been investigated by rat incisor organ culture and examination of the 32P and 14C labeled products. These studies all show marked differences in the Mr values for the PP from teeth of different species, even when they are antigenically cross-reactive.

Animals↗