Effects of the regulatory light chain phosphorylation of myosin II on mitosis and cytokinesis of mammalian cells

Myosin plays an important role in mitosis, especially during cytokinesis. Although it has been assumed that phosphorylation of regulatory light chain of myosin (RLC) controls motility of mammalian non-muscle cells, the functional significance of RLC phosphorylation remains uninvestigated. To address this problem, we have produced unphosphorylatable RLC (T18A/S19A RLC) and overexpressed it in COS-7 cells and normal rat kidney cells. Overexpression of T18A/S19A RLC but not wild type RLC almost completely abolished concanavalin A-induced receptor cap formation. The results indicate that myosin phosphorylation is critical for concanavalin A-induced gathering of surface receptors. T18A/S19A RLC overexpression resulted in the production of multinucleated cells, suggesting the failure of proper cell division in these cells. Video microscopic observation revealed that cells expressing T18A/S19A RLC showed abnormalities during mitosis in two respects. One is that the cells produced abnormal cleavage furrows, resulting in incomplete cytokinesis, which suggests that myosin phosphorylation is important for the normal recruitment of myosin molecules into the contractile ring structure. The other is that separation of chromosomes from the metaphase plate is disrupted in T18A/S19A RLC expressing cells, thus preventing proper transition from metaphase to anaphase. These results suggest that, in addition to cytokinesis, myosin and myosin phosphorylation play a role in the karyokinetic process.

Involvement of calcium-dependent protein kinase in rice (Oryza sativa L.) lamina inclination caused by brassinolide

Promotive effect of brassinolide (BL) on green lamina inclination was concentration-dependent when excised rice (Oryza sativa L.) lamina was floated on BL solution under continuous light conditions. Protein kinase inhibitor staurosporine and Ca2+ channel blocker LaCl3 could completely, while Ca2+ chelator EGTA could partially inhibit the lamina inclination caused by BL. Two protein kinases with apparent molecular masses of 45 and 54 kDa were detected using an in-gel kinase assay with histone III-S as a substrate. In particular, the changes in 45 kDa protein kinase activity correlated with lamina inclination caused by BL. The 45 kDa kinase activity was inhibited by Ca2+ chelator EGTA, protein kinase inhibitor, staurosporine and calmodulin antagonist W-7. Therefore, this 45 kDa protein kinase was identified as a Ca2+ -dependent protein kinase (CDPK). Patterns of 2-dimensional PAGE after in vitro phosphorylation of crude extracts showed that the phosphorylation of 56 and 41 kDa proteins, which was Ca2+ -dependent, was strongly increased by BL treatment. These results suggested that CDPK and Ca2+ -dependent protein phosphorylation are involved in BL-induced rice lamina inclination.

Molecular cloning and characterization of cDNAs encoding two isoforms of ribulose-1,5-bisphosphate carboxylase/oxygenase activase in rice (Oryza sativa L.)

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activase catalyzes the activation of RuBisCO in vivo. Two full length cDNAs designated as OsrcaA1 and OsrcaA2 encoding two RuBisCO activase isoforms of 47 and 43 kDa, respectively, have been cloned and characterized. The two isoforms were 99% identical, the 47 kDa isoform having an additional 33 amino acids and a 5 amino acid substitution at the carboxyl terminus. The deduced amino acid sequences of OsrcaA1 and OsrcaA2 showed 73-89% identity with RuBisCO activase from other higher plants. Two highly conserved ATP binding sites were identified. The Osrca mRNAs, and the RuBisCO activase proteins of 43 and 47 kDa were specifically detected in leaf, but not in root or etiolated seedling tissues. During leaf development, the abundance of Osrca mRNAs increased from the 7th to the 3rd leaf, and reached a maximum in the 2nd leaf, although the amounts of the 43 and 47 kDa RuBisCO activase remained almost unchanged among the six leaves, indicating the involvement of post-transcription control in the regulation of RuBisCO activase expression in rice. The co-immunoprecipitation of RuBisCO LSU and SSU with RuBisCO activase suggests that RuBisCO activase interacts with RuBisCO in vivo.

Effects of bradykinin on prostaglandin I(2) synthesis in human vascular endothelial cells

The effects of bradykinin on the regulatory mechanisms of prostacyclin synthesis in endothelial cells were investigated in association with intracellular Ca(2+) kinetics, cytosolic phospholipase A(2) (cPLA(2)) activity, and mRNA expression of cPLA(2) and prostaglandin H synthase (PGHS) isoforms. Bradykinin enhanced prostacyclin release from endothelial cells time-dependently, but pretreatment with EGTA H-7 or HOE 140 inhibited bradykinin-induced prostacyclin release. Bradykinin increased both the influx of extracellular Ca(2+) and Ca(2+) release from the intracellular Ca(2+) storage sites. These reactions occurred within 5 minutes after bradykinin stimulation. Within 15 minutes, bradykinin activated cPLA(2) to 1.3-fold the control level. The constitutive expressions of mRNA of cPLA(2), PGHS-1, and PGHS-2 was 87, 562, and 47 amol/microg RNA, respectively. With the stimulation of bradykinin, cPLA(2) mRNA increased to 746 amol/microg RNA in 15 minutes, PGHS-1 mRNA increased to 10 608 amol/microg RNA, and PGHS-2 mRNA increased to 22 400 amol/microg RNA in 180 minutes. Pretreatment with cycloheximide superinduced cPLA(2) and PGHS-2 mRNA expression but almost completely inhibited PGHS-1. Pretreatment with EGTA had effects similar to pretreatment with cycloheximide in the case of cPLA(2) and PGHS-1 but did not affect PGHS-2. These findings suggest that the elevation of cPLA(2) activity caused by the increase of intracellular Ca(2+) concentration is important in the early phase of bradykinin-induced prostacyclin synthesis and that the mechanisms regulating cPLA(2) are different from those regulating PGHS isoforms in endothelial cells.

Enteric microflora contribute to constitutive ICAM-1 expression on vascular endothelial cells

Quantitative estimates of endothelial cell adhesion molecule expression have revealed that some adhesion molecules [e.g., intercellular adhesion molecule-1 (ICAM-1)] are abundantly expressed in different vascular beds under normal conditions. The objective of this study was to determine whether the enteric microflora contribute to the constitutive expression of ICAM-1 and other endothelial cell adhesion molecules in the gastrointestinal tract and other regional vascular beds. The dual radiolabeled monoclonal antibody technique was used to measure endothelial expression of ICAM-1, ICAM-2, vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in conventional, germ-free mice and germ-free mice receiving the cecal contents of conventional mice to reestablish the enteric microflora (total association). Constitutive ICAM-1 expression was significantly lower in the splanchnic organs (pancreas, stomach, small and large intestine, mesentery, and liver), kidneys, skeletal muscle, and skin of germ-free mice compared with their conventional counterparts. These differences were abolished after total association of germ-free mice with the indigenous gastrointestinal flora. The expression of ICAM-2, VCAM-1, and E-selectin in the various tissues studied did not differ between conventional and germ-free mice. These findings indicate that the indigenous gastrointestinal microflora are responsible for a significant proportion of the basal ICAM-1 expression detected in both intestinal and extraintestinal tissues.

Role of jasmonate in the rice (Oryza sativa L.) self-defense mechanism using proteome analysis

Exogenously applied jasmonic acid (JA) was used to study changes in protein patterns in rice (Oryza sativa L.) seedling tissues, to classify these changes, and to assign a role for these changes, in order to define the role of JA in the rice self-defense mechanism. High resolution two-dimensional polyacrylamide gel electrophoretic analysis revealed induction of new proteins in both leaf and stem tissues after JA treatment, with the major protein spots further analyzed through N-terminal and internal amino acid sequencing, purification, antibody production, and immunoblot analysis. JA treatment results in necrosis in these tissues, which is accompanied by drastic reductions in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) subunits, and was confirmed using immunoblotting. Induction of novel proteins was found particularly in the stem tissues, including a new basic 28 kDa Bowman-Birk proteinase inhibitor protein (BBPIN; jasmonate-induced stem protein, JISP 6), and acidic 17 kDa pathogenesis-related class 1 protein (PR-1, JISP 9). This induction of proteins was blocked by a protein synthesis inhibitor cycloheximide (CHX) indicating de novo protein synthesis. Kinetin (KIN), a cytokinin and free radical scavenger reversed RuBisCO decreases, but not induction of proteins. Immunoblot analysis using antibodies generated against these purified proteins revealed a tissue-specific expression pattern and time-dependent induction after JA treatment. Our results indicate that jasmonate affects defense-related gene expression in rice seedlings, as evidenced by de novo synthesis of novel proteins with potential roles in plant defense.

Mitotic index is the best predictive factor for survival of patients with resected hepatocellular carcinoma

BACKGROUND

In patients with hepatocellular carcinoma (HCC), tumor recurrence is not infrequent after resection. It is presumed that characteristics of the tumor such as cellular malignancy might influence the prognosis of the patients in association with tumor stage and radicality of the procedure.

METHODS

Univariate and multivariate analyses were used to retrospectively determine the clinicopathologic factors potentially related to survival in 40 patients who underwent hepatectomy for HCC.

RESULTS

In univariate analysis, tumor stage I or II, mitotic index of 4 or less/10 random high-power fields, solitary tumor, and curative resection were significantly correlated with better survival. In multivariate analysis, the mitotic index and surgical curability were independently significant variables influencing survival of patients, and the mitotic index was the best predictive factor. A highly significant correlation was found between the mitotic index and Ki-67 labeling index. Compared to tumors with a mitotic index of 4 or less, those with a mitotic index of 5 or more had a higher association with multiple tumors and advanced tumor stage, which preclude curative resection.

CONCLUSION

Analysis of the mitotic index is quite simple, and the mitotic index could be a useful factor for predicting the long-term survival of patients with HCC following hepatic resection.

Targeting activated lymphocytes with an entirely human immunotoxin analogue: human pancreatic RNase1-human IL-2 fusion

A hybrid human protein was produced in E. coli by fusing the genes encoding human pancreatic RNase1 (hpRNase1) and human IL-2 (hIL-2). The recombinant hpRNase1-hIL-2 inhibited protein synthesis in HTLV-1-infected, malignant T cells, which hyperproduce high affinity IL-2 receptors, with an IC(50)of 2x10(-8) M, whereas no inhibition was detectable in control cells with lower affinity receptors. HpRNase1 alone had an IC(50)of almost 10(-3) M. A molar excess of hIL-2 blocked the protein synthesis inhibition dose-dependently. In a human mixed lymphocyte culture, hpRNase1-hIL-2 inhibited the proliferation of responder cells with potency comparable to that of cyclosporine, while non-effective doses of FK506 importantly improved its potency. Despite its short half-life in animals, hpRNase1-hIL-2 rapidly enters cells in a few minutes and arrests the protein translation in less than 10 h. Thus, hpRNase1-hIL-2 may be useful to selectively eliminate activated lymphocytes hyperproducing high affinity IL-2 receptors, as in allograft rejection, graft-versus-host disease, autoimmune disorders, adult T cell leukaemia and other lymphoproliferative or retroviral malignancies including HIV infection, without inducing general immunosuppression. As an entirely human "immunotoxin analogue" it may alleviate the dose limiting toxicity and immunogenicity of conventional immunotoxins.

Immune responses against replication-deficient adenovirus inhibit ovalbumin-specific allergic reactions in mice

Replication-deficient adenovirus vector (Ad) is one of the most efficient gene transfer vehicles for human gene therapy. However, Ad is antigenic, known to evoke prominent inflammatory responses in vivo, and there are concerns that using Ad in patients with immune-mediated disorders (allergy and autoimmune diseases) may affect the status of the diseases. To evaluate this concept in a manner close to clinical scenarios, a mouse model of airway eosinophilic inflammation was developed by administering intraperitoneal injections and inhalations of chicken ovalbumin (OA), with Ad administered intranasally 5 days after the OA sensitization. The administration of Ad resulted in a significant suppression of eosinophil counts in peripheral blood as well as in the bronchoalveolar lavage fluid (BALF), and a decrease in OA-specific IgE. The decrease in the number of eosinophils in BALF was associated with a marked upregulation of interferon gamma (IFN-gamma) expression. In contrast, the Ad-specific, delayed-type hypersensitivity response and efficacy of reporter gene expression mediated by Ad were only marginally affected in animals sensitized with OA. Together, these data support the idea that Ad administration in patients with Th2-mediated immune disorders does not exacerbate the parameters of ongoing inflammations or gene transfer efficiency, and with its ability to induce prominent type 1 immune response to the antigen in vivo, Ad could potentially be used as an efficient adjuvant to control immune disorders where Th2 cell-mediated mechanisms are involved.

Molecular cloning and characterization of calreticulin, a calcium-binding protein involved in the regeneration of rice cultured suspension cells

A full-length cDNA clone encoding a phosphoprotein (pp56) involved in the regeneration of rice (Oryza sativa L.)-cultured suspension cells was isolated by screening a rice cultured suspension cell cDNA library. The 1558-bp cDNA sequence contains an ORF encoding an acidic (pI 4.38) protein of 424 amino acids (47.9 kDa), sharing 70-93% and 50-53% homology with other plant and mammalian calreticulins, respectively. Sequence analysis of the cDNA clone revealed several significant conserved motifs, including a calreticulin family repeat motif in the central domain and two calreticulin family motifs in the N-domain, indicating that this gene is a rice calreticulin (CRO1). The CRO1 gene in long-term rice cultured suspension cells shows constitutive expression in both suspension culture and regeneration media. In contrast, expression of the CRO1 gene in short-term rice cultured suspension cells, which possess regeneration potential, is increased dramatically when these cells are transferred to the regeneration medium. After approximately 2 weeks in the regeneration medium, the expression of the CRO1 gene reverts to constitutive levels. These results demonstrate the presence of calreticulin in rice cultured suspension cells and its developmental regulation during the regeneration of rice cultured suspension cells.

[Werner's syndrome associated with acute myelofibrosis]

A 47-year-old man was admitted to our hospital in June 1997 because of nasal bleeding. He presented with anemia in addition to physical characteristics of Werner's syndrome (WS). Peripheral blood examination disclosed pancytopenia with 4% blasts. Bone marrow aspiration was a dry tap; biopsy specimens revealed myelofibrosis. Chromosomal analysis of peripheral blood revealed hypodiploidy with complex abnormalities including -5 and del(7)(q21). Serum levels of PDGF, FGF, and TGF beta 1 were normal. A diagnosis of acute myelofibrosis was made. The patient's condition became quickly deteriorated and he died of pneumonia in October 1997. In the literature, we found 6 reported cases of myelofibrosis associated with WS. Considering that only approximately 1,100 cases of WS have been reported so far, the incidence of myelofibrosis in WS seems relatively high. This case suggested a link between WS and myelofibrosis, and the mechanism of myelofibrosis in WS was discussed.

Methylation and downregulated expression of mac25/insulin-like growth factor binding protein-7 is associated with liver tumorigenesis in SV40T/t antigen transgenic mice, screened by restriction landmark genomic scanning for methylation (RLGS-M)

Restriction landmark genomic scanning for methylation (RLGS-M) was used to detect alterations in DNA methylation associated with murine SV40 T/t antigen-induced hepatocarcinogenesis. An altered locus/spot (S130) was cloned and found to correspond to sequences in the 5' flanking region and 5' portion of the cDNA for the murine mac25/insulin-like growth factor binding protein-7 (Igfbp-7) gene. IGFBPs are believed to be capable of binding insulin, Igf1, and Igf2 and modulating mitogenic effects. Previous studies have shown that Igf2 has an important role in promoting liver tumorigenesis. Quantitative PCR was used to access the methylation status of the NotI site just 5' to the coding region and the expression level of the mac25/igfbp-7 gene. The results indicated that the degree of methylation was inversely related to the expression level and is consistent with a role for DNA methylation in silencing mac25/Igfbp-7 gene expression and function for mac25/Igfbp-7 as a tumor suppressor gene.

N-terminal amino acid sequences of prolamins encoded by the alleles at the Pro1 and Pro2 loci in foxtail millet, Setaria italica (L.) P. Beauv

N-terminal amino acid sequences of six prolamins encoded by seven alleles at two loci, Pro1 and Pro2, of foxtail millet (Setaria italica (L.) P. Beauv.) were analyzed and compared with other prolamins of subfamily Panicoideae. Based on the N-terminal amino acid sequences, band 3 (the prolamin purified from band 3) which is controlled by an allele at the Pro1 locus and bands 1, 2, 4, 5 and 6 which are controlled by alleles at the Pro2 locus could be classified into three groups. Band 3 was found to be homologous to the prolamin of pearl millet (Pennisetum americanum) and is designated as the "pennisetin-like prolamin". Bands 2 and 4, and bands 1, 5 and 6 were subdivided into "x-type prolamin" and "y-type prolamin". Both of the x-type and y-type prolamins showed homology with prolamin of Echinochloa crus-galli and alpha-zein-like prolamins of maize, sorghum and Job's tears. Therefore, these prolamins were designated as "alpha-zein-like prolamin". These results suggest that alleles at the Pro1 locus and those at the Pro2 locus have not arisen from an identical ancestral gene, and that the Pro2 locus comprise two tightly linked genes, which encode similar prolamins. Hypotheses on the diversification of alleles at the Pro2 locus are discussed based on the N-terminal amino acid sequences of the respective bands, combinations of bands controlled by the alleles, and frequencies of the alleles.

Abnormal expression of tyrosine hydroxylase immunoreactivity in Purkinje cells precedes the onset of ataxia in dilute-lethal mice

Expression of tyrosine hydroxylase (TH) immunostaining in the cerebellum was examined in dilute-lethal mice (DL) prior to and following the onset of ataxia. DL walked normally on postnatal days 7 and 8. Falling over when walking was exhibited by about 20% of DL on day 9 and by all DL by day 10. TH-positive Purkinje cells in lobules IX and X of the vermis of either ataxic or non-ataxic DL were clearly observed on day 9 when compared to control mice, and had drastically increased by day 10. These results revealed that abnormal TH expression occurred in some Purkinje cells of DL cerebella, preceding the onset of ataxia.

A role of protein kinase C in the regulation of cytosolic phospholipase A(2) in bradykinin-induced PGI(2) synthesis by human vascular endothelial cells

The purpose of this study was to elucidate the mechanism by which bradykinin (BK) enhances prostacyclin (PGI(2)) production in human umbilical vein endothelial cells (HUVEC). BK-induced enhancement of PGI(2) synthesis was observed in a dose- and time-dependent manner, and it also increased [Ca(2+)](i) followed by enhancement of cytosolic phospholipase A(2) (cPLA(2)) activity. The PKC inhibitors GF109203X and H7 attenuated the BK-induced increase in [Ca(2+)](i) and inhibited the BK-induced PGI(2) synthesis. Phorbol 12-myristate 13-acetate increased cPLA(2) activity and PGI(2) synthesis but failed to alter [Ca(2+)](i). BK increased cPLA(2) mRNA eightfold by 15 min, and this increase was inhibited by pretreatment with the PKC inhibitors. In response to cycloheximide pretreatment, cPLA(2) mRNA was superinduced. These results suggest that BK stimulates PGI(2) synthesis in HUVEC by activation of cPLA(2) by dual mechanisms: an elevation of [Ca(2+)](i) and a PKC-dependent pathway. Moreover, changes in calcium kinetics and expression of cPLA(2) mRNA may underlie the BK-induced PGI(2) enhancement in these cells.

The mechanism of thrombin-induced prostacyclin synthesis in human endothelial cells with reference to the gene transcription of prostacyclin-related enzymes and Ca2+ kinetics

This study was designed to evaluate the effect of thrombin on prostacyclin (PGI2) production in cultured human vascular endothelial cells in association with intracellular Ca2+ and with the gene expression of prostaglandin H2 synthase (PGHS) and phospholipase A2 (PLA2) using competitive polymerase chain reaction. Thrombin enhanced the PGI2 synthesis dependent with time. Additionally, thrombin increased the intracellular Ca2+, which stimulates PLA2, resulting in arachidonic acid cleavage from membrane phospholipids and its subsequent conversion into PGI2 through the PGHS pathway. The elevation of intracellular Ca2+ was a result of Ca2+ influx and Ca2+ release from its intracellular storage sites. In this study, PGHS-1 mRNA was constitutively expressed, whereas PGHS-2 mRNA was not. With the stimulation of thrombin, cytosolic PLA2 (cPLA2) mRNA increased 9-fold at 15 min, PGHS-1 mRNA increased 3.4-fold at 180 min, and PGHS-2 mRNA increased 38-fold at 60 min. These results suggest that the elevation of intracellular Ca2+ and the expression of cPLA2, PGHS-1, and PGHS-2 mRNA cause PGI2 generation.

Interleukin-1alpha stimulated prostacyclin release by increasing gene transcription of prostaglandin H synthase and phospholipase A2 in human vascular endothelial cells

This study was conducted to evaluate the effects of interleukin-1alpha (IL-1alpha) on prostacyclin (PGI2) production in cultured human vascular endothelial cells in association with intracellular Ca2+, inositol 1,4,5-trisphosphate (IP3), and with prostaglandin H synthase (PGHS) and phospholipase A2 (PLA2) gene expression by using the competitive polymerase chain reaction (PCR) method. IL-1alpha did not increase PGI2 production for 15 min, but induced an increase of about three-fold relative to that in controls at 60 and 180 min. IL- 1alpha had no effect on intracellular Ca2+ levels throughout the experimental period. In this study, consistent with previous reports, PGHS-1 messenger RNA (mRNA) was constitutively expressed, whereas PLA2 mRNA was not. After stimulation with IL-1alpha, PLA2 mRNA level showed an eightfold increase within 15 min, and PGHS-2 mRNA level increased by 76-fold within 180 min. PGHS-1 mRNA level was increased 1.6-fold at 180 min. These results suggest the existence of regulatory mechanisms of IL-1alpha-induced PGI2 production, which involve PGHS and PLA2 gene transcription.

Abnormal expression of tyrosine hydroxylase immunoreactivity in cerebellar cortex of ataxic mutant mice

Expression of tyrosine hydroxylase (TH) was examined immunohistochemically in the cerebellum of two ataxic mutants, Rolling mouse Nagoya (RMN) and dilute-lethal mice (DL). In littermate controls of both mutants, a few TH-positive Purkinje cells were distributed sparsely and their number was smaller than in the mutants at any ages examined. In RMN, TH-positive Purkinje cells were distributed in lobule IX and X, and were arranged into parasagittal bands at 2 weeks of age. TH-positive Purkinje cells increased in number and were widely distributed throughout the vermis at 3 weeks of age. In adult RMN, TH-positive Purkinje cells were found in all lobules of the cerebellum. Their parasagittal bands also became evident in the hemisphere. In DL, TH-positive Purkinje cells were mainly distributed in vermal lobules IX and X, and the flocculus at 3 weeks of age. They were also found as bands in lobules IX and X. The results suggest that abnormal expression of TH in Purkinje cells may not be specific to the allelic group. Since TH promoter is activated by Ca2+, TH expression in the mutant Purkinje cells may predict neuronal dysfunction caused by alterations in cellular Ca2+ currents.

Serum retinol level and risk of subsequent cervical cancer in cases with cervical dysplasia

We followed up on 134 women who had been diagnosed with cervical dysplasia to examine the relationship of dietary and serum vitamin A to subsequent cervical cancer. The subjects were women attending the Papanicolaou test screening for residents in Miyagi, Japan and histologically diagnosed as having cervical dysplasia between October 1987 and September 1988. Personal interviews were carried out, and blood samples were taken on the date of diagnosis of cervical dysplasia. The subjects were followed-up with cervical smear and colposcopy at about 3-month intervals from the date of interview until the end of February 1995. During the follow-up, 8 women (5.9%) developed cancer in situ or invasive cervical cancer and 106 (79.1%) reverted to normal. The rate of progression of the cancer in situ or invasive cervical cancer was 4.5 times higher in women with lower serum retinol levels than those with higher serum retinol levels (p = 0.08). The results suggest an association of low serum retinol level with development of cervical cancer.

Studies on the kinetics, metabolism and re-utilisation after intra-articular administration of hyaluronan to rabbits

The pharmacokinetics of hyaluronan (HA) (CAS 9004-61-9) was measured after intra-articular (i.a.) injection of 1 mg/kg of 14C-glucose-labelled HA (14C-HA) (i.e. 2,000 kDa) into the knee joint cavity of rabbits. The movement of HA from the cavity into the systemic circulation was assessed by measuring its concentration in blood and its residue in the cavity. I.a. HA moved into, and disappeared from, the bloodstream at a first-order rate. Synovial fluid, synovial membrane and articular cartilage specimens were taken 24 and 72 h post-injection, and the molecular weight (MW) of HA fractions were measured by using gel filtration chromatography (GFC) using radioactive fractions of known molecular sizes (i.e. 2,000 kDa, 300 kDa and 50 kDa). The radioactivity distribution of synovial fluid had a peak at a 2,000 kDa-equivalent fraction at both 24 and 72 h post-injection, while synovial membrane had a peak at a 300 kDa-equivalent fraction 24 h post-injection and at a 50 kDa-equivalent fraction 72 h post-injection. The radioactivity distribution pattern of articular cartilage showed peaks corresponding to 2,000-300 kDa 24 h post-injection and to 50 kDa 72 h post-injection. The in vivo re-utilisation of i.a. HA was investigated by assessing radioactivity in the acid-soluble, lipid and protein fractions of plasma, blood cells and liver 72 h post-injection. Results show that HA was broken down into C1 units (carbon cycle) before being re-used as an in vivo constituent in the body.

Separation and characterization of proteins from green and etiolated shoots of rice (Oryza sativa L.): towards a rice proteome

Proteins extracted from green and etiolated shoots of rice were separated by two-dimensional polyacrylamide gel electrophoresis and relative molecular weights and isoelectric points were determined. The separated proteins were electroblotted onto a polyvinylidene difluoride membrane and 85 proteins were analyzed by a gas-phase protein sequencer. The N-terminal amino acid sequences of 21 out of 85 proteins were determined in this manner. N-terminal regions of the remaining proteins could not be sequenced. The internal amino acid sequences of proteins were determined by sequence analysis of peptides obtained by the Cleveland peptide mapping method and compared with those of known plant and animal protein sequences to understand the nature of the proteins. Green shoots revealed the presence of photosynthetic proteins as expected; however, as etiolated shoots were not photosynthetic, only precursors of the photosynthetic proteins were identified. Interestingly, the presence of L-ascorbate peroxidase only in etiolated shoots suggests a cellular protectant function for this antioxidant enzyme in the etiolating shoots. Using this experimental approach, we could identify the major proteins involved in growth regulation in photosynthetic green shoots as well as in etiolating rice seedlings.

Separation and characterization of proteins from green and etiolated shoots of rice (Oryza sativa L.): towards a rice proteome

Proteins extracted from green and etiolated shoots of rice were separated by two-dimensional polyacrylamide gel electrophoresis and relative molecular weights and isoelectric points were determined. The separated proteins were electroblotted onto a polyvinylidene difluoride membrane and 85 proteins were analyzed by a gas-phase protein sequencer. The N-terminal amino acid sequences of 21 out of 85 proteins were determined in this manner. N-terminal regions of the remaining proteins could not be sequenced. The internal amino acid sequences of proteins were determined by sequence analysis of peptides obtained by the Cleveland peptide mapping method and compared with those of known plant and animal protein sequences to understand the nature of the proteins. Green shoots revealed the presence of photosynthetic proteins as expected; however, as etiolated shoots were not photosynthetic, only precursors of the photosynthetic proteins were identified. Interestingly, the presence of L-ascorbate peroxidase only in etiolated shoots suggests a cellular protectant function for this antioxidant enzyme in the etiolating shoots. Using this experimental approach, we could identify the major proteins involved in growth regulation in photosynthetic green shoots as well as in etiolating rice seedlings.

Effect of probucol on intracellular pH and proliferation of human vascular endothelial cells

We investigated the effect of probucol on the intracellular pH ([pH]i) and proliferation of human umbilical vein endothelial cells (HUVEC), as well as their production of prostacyclin (PGI2). The addition of probucol produced a biphasic shift in [pH]i, with a brief initial acidification followed by a rapid alkaline shift. After pretreatment with EGTA, the initial decrease in [pH]i was abolished, and the subsequent increase was inhibited. After pretreatment with amiloride, only the increase of [pH]i was abolished. These results suggest that the probucol-induced increase of [pH]i was mainly dependent on Na+/H+ exchange and partly on extracellular Ca2+. In contrast, the addition of LDL produced a decrease of [pH]i. Under Ca2+-free condition, [pH]i was further decreased by LDL. In cells pretreated with amiloride, however, [pH]i was not further decreased by LDL. It was found that probucol promoted cell proliferation, and LDL inhibited cell proliferation. Addition of probucol also enhanced prostacyclin generation by HUVEC. This enhancement of PGI2 generation resulted from increased release of Ca2+ from the storage sites, due not only to increased production of inositol 1,4,5-triphosphate (IP3) but also to the increase of [pH]i. These findings may help to explain the antiatherosclerotic action of probucol.