A novel action of collapsin: collapsin-1 increases antero- and retrograde axoplasmic transport independently of growth cone collapse

Chick collapsin-1, a member of the semaphorin family, has been implicated in axonal pathfinding as a repulsive guidance cue. Collapsin-1 induces growth cone collapse via a pathway which may include CRMP-62 and heterotrimeric G proteins. CRMP-62 protein is related to UNC-33, a nematode neuronal protein required for appropriately directed axonal extension. Mutations in unc-33 affect neural microtubules, the basic cytoskeletal elements for axoplasmic transport. Using computer-assisted video-enhanced differential interference contrast microscopy, we now demonstrate that collapsin-1 potently promotes axoplasmic transport. Collapsin-1 doubles the number of antero- and retrograde-transported organelles but not their velocity. Collapsin-1 decreases the number of stationary organelles, suggesting that the fraction of time during which a particle is moving is increased. Collapsin-1-stimulated transport occurs by a mechanism distinct from that causing growth cone collapse. Pertussis toxin (PTX) but not its B oligomer blocks collapsin-induced growth cone collapse. The holotoxin does not affect collapsin-stimulated axoplasmic transport. Mastoparan and a myelin protein NI-35 induce PTX-sensitive growth cone collapse but do not stimulate axoplasmic transport. These results provide evidence that collapsin has a unique property to activate axonal vesicular transport systems. There are at least two distinct pathways through which collapsin exerts its actions in developing neurons.

Mice lacking the vitamin D receptor exhibit impaired bone formation, uterine hypoplasia and growth retardation after weaning

1 alpha,25-Dihydroxyvitamin D3[1 alpha,25(OH)2D3], an active form of vitamin D, has roles in many biological phenomena such as calcium homeostasis and bone formation, which are thought to be mediated by the 1 alpha,25(OH)2D3 receptor (VDR), a member of the nuclear hormone receptor superfamily. However, the molecular basis for the actions of 1 alpha,25(OH)2D3 in bone formation, its role during development and VDR genetic polymorphisms for predicting bone mineral density are uncertain. To investigate the functional role of VDR, we generated mice deficient in VDR by gene targeting. We report here that in VDR null mutant mice, no defects in development and growth were observed before weaning, irrespective of reduced expression of vitamin D target genes. After weaning, however, mutants failed to thrive, with appearance of alopoecia, hypocalcaemia and infertility, and bone formation was severely impaired as a typical feature of vitamin D-dependent rickets type II (refs 8, 9). Unlike humans with this disease, most of the null mutant mice died within 15 weeks after birth, and uterine hypoplasia with impaired folliculogenesis was found in female reproductive organs. These defects, such as alopoecia and uterine hypoplasia, were not observed in vitamin D-deficient animals. The findings establish a critical role for VDR in growth, bone formation and female reproduction in the post-weaning stage.

Neuropeptide-containing nerve fibres in the human parotid gland: a semiquantitative analysis using an antibody against protein gene product 9.5

The occurrence and distribution of neuropeptide-containing fibres in the human parotid gland were examined by the peroxidase-antiperoxidase method with attention to the quality of fixation and the condition of patients. Many fibres immunoreactive for neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) and a moderate number of galanin-positive (GAL) fibres were distributed around the acini. A moderate number of NPY and VIP fibres were distributed around the intercalated ducts. The semiquantitative mean densities (+/- SD) of periacinar NPY, VIP and GAL fibres expressed as a percentage of the total protein gene product (PGP) 9.5 immunoreactive fibres were 75.62 +/- 7.25%, 70.52 +/- 9.33% and 41.76 +/- 5.45%, respectively, whereas those of substance P (SP), calcitonin gene-related peptide (CGRP) and FMRF amide (FMRF) fibres were below 10%. The mean densities of NPY and VIP fibres around the intercalated ducts expressed as the percentage of PGP 9.5 fibres associated with these ducts were 52.37 +/- 6.19% and 59.62 +/- 7.02% respectively. Those of SP, CGRP, GAL, and FMRF fibres were below 10%. The densities of NPY, VIP, SP, CGRP, GAL and FMRF fibres around the striated and excretory ducts were also below 10%. In the vasculature, NPY fibres were the most prominent. Similarly, the mean density of perivascular NPY fibres was 93.76 +/- 2.03%. No somatostatin or leucine or methionine enkephalin immunoreactivity was detected around the acini, duct system or blood vessels. These findings suggest that, in this gland, the periacinar NPY, VIP and GAL fibres may participate in regulating the synthesis of saliva and its secretion and that perivascular peptidergic fibres, especially NPY fibres, may be involved in controlling local blood flow.

[The clinical efficacy of imipenem/cilastatin sodium in orthopedic infections and drug levels in the bone tissue]

We evaluated the clinical efficacy of imipenem/cilastatin sodium (IPM/CS--a carbapenem antibiotic) against orthopedic infections, and the drug levels of the bone tissues were determined. The clinical efficacies for 6 patients in the infection group were good in 3 cases, and fair in the other 3; giving an efficacy rate of 50%. Bacteriologically, 8 strains were isolated from patients with the infection and an eradication rate of 87.5% was obtained upon the treatment. In 39 patients that were given the drug prophylactically, no postoperative infections occurred. Mean IPM levels in the bone and the bone marrow at 1 hour after administration in 5 patients of the prophylactic group were 17.3 micrograms/ml and 5.9 micrograms/g, respectively. The ratio of concentrations the bone to those in the bone marrow was 34.6%. The results of this study suggest that IMP/CS reaches to the bone tissue providing sufficient concentrations and that the drug is efficacious for the prophylaxis and the treatment of orthopedic infections.

Chromosomal aberration in lipoblastoma: a case with 46,XX,ins(8;6)(q11.2;q13q27)

Chromosomal aberrations involving 8q11.2 have been reported in lipoblastoma. We report here a case of lipoblastoma with new chromosomal aberration. 46,XX,ins(8;6)(q11.2;q13q27). Cytogenetic analysis would facilitate the clinical differentiation between myxoid liposarcoma and the pathologically similar lipoblastoma and the identification of genetic loci related to cellular growth.

[A case of ruptured aortic arch aneurysm with hemorrhagic cardiac tamponade]

The ruptured thoracic aortic aneurysm is still a dramatic even with very poor outcome, whereby its survival depends largely on early diagnosis and operation. We report a successful case of aortic arch replacement for ruptured aortic arch aneurysm with cardiac tamponade. Lethal hemopericardium causing cardiac tamponade is most commonly seen as a complication of acute myocardial infarction or acute aortic dissection, and subsequent rupture of the heart or ascending aorta leads to the rapid accumulation of blood within the poorly distensible pericardial sac. Our case was operated upon emergency basis due to hemopericardium. On operative findings, the aortic aneurysm located the minor curvature of aortic arch and was a huge saccular shape. In surgical procedure, the total arch replacement was completed using selective cerebral antegrade perfusion with deep hypothermia. Postoperative course was uneventful and no cerebral complication was observed after surgery.

Interactions between protein kinase C and pleckstrin homology domains. Inhibition by phosphatidylinositol 4,5-bisphosphate and phorbol 12-myristate 13-acetate

Pleckstrin homology (PH) domains comprised of loosely conserved sequences of approximately 100 amino acid residues are a functional protein motif found in many signal-transducing and cytoskeletal proteins. We recently demonstrated that the PH domains of Tec family protein-tyrosine kinases Btk and Emt (equal to Itk and Tsk) interact with protein kinase C (PKC) and that PKC down-regulates Btk by phosphorylation. In this study we have characterized the PKC-BtkPH domain interaction in detail. Using pure PKC preparations, it was shown that the Btk PH domain interacts with PKC with high affinity (KD = 39 nM). Unlike other tested phospholipids, phosphatidylinositol 4,5-bisphosphate, which binds to several PH domains, competed with PKC for binding to the PH domain apparently because their binding sites on the amino-terminal portion of the PH domains overlap. The minimal PKC-binding sequence within the Btk PH domain was found to correspond roughly to the second and third beta-sheets of the PH domains of known tertiary structures. On the other hand, the C1 regulatory region of PKCepsilon containing the pseudosubstrate and zinc finger-like sequences was found to be sufficient for strong binding to the Btk PH domain. Phorbol 12-myristate 13-acetate (PMA), a potent activator of PKC that interacts with the C1 region of PKC, inhibited the PKC-PH domain interaction, whereas the bioinactive PMA (4-alpha-PMA) was ineffective. The zeta isoform of PKC, which has a single zinc finger-like motif instead of the two tandem zinc finger-like sequences present in conventional and novel PKC isoforms, does not bind PMA. Thus, as expected, PH domain binding with PKCzeta was not interfered with by PMA. Further, inhibitors that are known to attack the catalytic domains of serine/threonine kinases did not affect this PKC-PH domain interaction. In contrast, the presence of physiological concentrations of Ca2+ induced less than a 2-fold increase in PKC-PH domain binding. These results indicate that PKC binding to PH domains involve the beta2-beta3 region of the Btk PH domain and the C1 region of PKC, and agents that interact with either of these regions (i.e. phosphatidylinositol 4,5-bisphosphate binding to the PH domain and PMA binding to the C1 region of PKC) might act to regulate PKC-PH domain binding.

Effect of dibutyryl cyclic AMP on axoplasmic transport in the hippocampus

The effect of dibutyryl cyclic AMP (dbcAMP) on axoplasmic transport of cultured hippocampal neuron cells from postnatal 1-day mice was analyzed with a computer-assisted video-enhanced differential interference contrast microscope system. Dibutyryl cyclic AMP increased the axoplasmic transport in both anterograde and retrograde directions. The number of particles flowing in the neurites was increased by 0.5 mM dbcAMP. The peak reached about 160% of the initial value. The instantaneous velocity of axoplasmic transport was also increased by 0.5 mM dbcAMP. The average velocity of anterograde and retrograde direction changed respectively from 1.95 +/- 1.01 microm/s (n = 55) to 2.66 +/- 1.26 microm/s (n = 58) and from 1.94 +/- 0.85 (n = 57) to 2.39 +/- 0.93 (n = 57). Rates were 136.1 and 123.1%, respectively. Previously, we have found that acetylcholine suppressed and adrenaline increased the axoplasmic transport in superior cervical ganglion cells. These effects are related to the amount of endogeneous cAMP. The results of the present report suggest that endogeneous cAMP is also related to hippocampal axoplasmic transport.

Peptidergic innervation in human von Ebner's glands: an immunohistochemical study

The occurrence and distribution of several neuropeptides were studied in human von Ebner's glands. Immunoreactivity for substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), galanin, and somatostatin was found in the nerve fibers around the acini, ducts, and blood vessels. VIP-immunoreactive varicose fibers were numerous compared with the other five neuropeptides. Most NPY fibers were associated with the vasculature in the gland. These findings suggest that the neuropeptides may regulate the secretion and vascular tone in human von Ebner's glands.

Bruton's tyrosine kinase regulates apoptosis and JNK/SAPK kinase activity

Mast cells derived from Bruton's tyrosine kinase (Btk)-defective xid or btk null mice showed greater expansion in culture containing interleukin-3 (IL-3) than those from wild-type (wt) mice. Although the proliferative response to IL-3 was not significantly different between the wt and xid mast cells, xid and btk null mast cells died by apoptosis more slowly than their wt counterparts upon IL-3 deprivation. Consistent with these findings, the apoptosis-linked c-Jun N-terminal kinase/stress-activated protein kinase (JNK) activity was compromised in these btk-mutated cells upon Fc(epsilon)RI crosslinking or upon stimulation with IL-3 or with stem cell factor. p38 activity was less severely, but significantly, affected by btk mutation, whereas extracellular signal-regulated kinases were not affected by the same mutation. Btk-mediated regulation of apoptosis and JNK activity was confirmed by reconstitution of btk null mutant mast cells with the wt btk cDNA. Furthermore, growth factor withdrawal induced the activation and sustained activity of JNK in wt mast cells, while JNK activity was consistently lower in btk-mutated mast cells. These results support the notion that Btk regulates apoptosis through the JNK activation.

Distribution of neuropeptide-containing nerve fibers in the human submandibular gland, with special reference to the difference between serous and mucous acini

Distribution of neuropeptide Y (NPY)-, vasoactive intestinal polypeptide (VIP)-, galanin (GAL)-, substance P (SP)-, and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in the human submandibular gland was examined by the peroxidase-antiperoxidase method with attention to high-quality fixation and the condition of patients. NPY-, VIP-, and GAL-immunoreactive varicose fibers were densely distributed around the acini and ducts. Some of these fibers extended between acinar cells. The density of SP- and CGRP-immunoreactive fibers was relatively low. The number of NPY-, VIP-, and GAL-immunoreactive fibers around the mucous acini was significantly higher than around the serous acini. In the perivasculature, NPY-immunoreactive fibers were more numerous than other immunoreactive fibers. No somatostatin-, leucine-, or methionine-enkephalin-immunoreactive fibers were detected. Our findings suggest that a large number of periacinar VIP-, NPY-, and GAL-immunoreactive fibers may participate in regulating the synthesis of saliva and its secretion. Since the VIP-, NPY-, and GAL-immunoreactive fibers are more numerous around the mucous acini than around the serous ones, these fibers may take part more actively in regulating the secretory mechanisms in the mucous acini than in the serous ones. The relatively low number of CGRP- and SP-immunoreactive fibers suggests that they are less involved in the function of the human submandibular gland. Perivascular peptidergic fibers, especially NPY-immunoreactive fibers, may be involved in controlling local blood flow in this gland.

Evaluation of heterotopic bone formation induced by squalane and bone morphogenetic protein composite

Bone morphogenetic protein is an important molecule whose bioactivity depends on the carrier. Squalane is used in the formulation of various kinds of cosmetics because it is easily emulsified and has the property of spreading well. Thus, squalane might be effective as a bone morphogenetic protein delivery system. As a test for this possibility, gelatin capsules containing squalane and bone morphogenetic protein (bovine derived partially purified) composite were implanted under the hind-quarter perimuscular membrane of ddY mice. Control capsules containing only bone morphogenetic protein were used for controls. The implants were radiographically and histologically examined at 1 to 4 weeks after the operation. According to the radiographic analysis, squalane and bone morphogenetic protein composite and bone morphogenetic protein only control specimens formed widespread heterotopic bone tissues. The amount of heterotopic bone formation in the composite experimental specimens was approximately 40% greater than that in the controls. Histologic examination of experimental and control specimens revealed varying amounts of perichondral ossification by 2 weeks. By 3 and 4 weeks, the bone deposits were colonized by hematopoietic bone marrow. Squalane was effective for the slow local release of bone morphogenetic protein. Furthermore, the squalane and bone morphogenetic protein composite was a reliable osteoinductive biomaterial.

[Premixing lidocaine reduces the incidence and severity of pain on injection of propofol]

The purpose of this study was to confirm the effect of premixed lidocaine for the reduction of pain during injection of propofol in adult patients. We conducted a prospective, randomized, double-blind trial on 106 patients. In the study group (n = 54), lidocaine 40 mg (2 ml of lidocaine 2%) was added to 180 mg of propofol (18 ml). In the control group (n = 52), 2 ml of normal saline was added to 180 mg of propofol. The pain on injection was rated as none, mild, moderate, or severe. Eleven patients (20.4%) in the study group experienced pain compared with 25 (48.1%) in the control group. Thirteen in the control group complained moderate or severe pain compared with only one in the study group. In conclusion, lidocaine 40 mg premixed with 180 mg propofol significantly reduces the incidence and severity of pain associated with propofol injection.

Advanced glycation end products-driven angiogenesis in vitro. Induction of the growth and tube formation of human microvascular endothelial cells through autocrine vascular endothelial growth factor

This study was undertaken to determine whether and how advanced glycation end products (AGE), senescent macroproteins accumulated in various tissues under hyperglycemic states, cause angiogenesis, the principal vascular derangement in diabetic microangiopathy. We first prepared AGE-bovine serum albumin (BSA) and anti-AGE antiserum using AGE-RNase A. Then AGE-BSA was administered to human skin microvascular endothelial cells in culture, and their growth was examined. The AGE-BSA, but not nonglycated BSA, was found to induce a statistically significant increase in the number of viable endothelial cells as well as their synthesis of DNA. The increase in DNA synthesis by AGE-BSA was abolished by anti-AGE antibodies. AGE-BSA also stimulated the tube formation of endothelial cells on Matrigel. We obtained the following evidence that it is vascular endothelial growth factor (VEGF) that mainly mediates the angiogenic activities of AGE. (1) Quantitative reverse transcription-polymerase chain reaction analysis of poly(A)+ RNA from microvascular endothelial cells revealed that AGE-BSA up-regulated the levels of mRNAs for the secretory forms of VEGF in time- and dose-dependent manners, while endothelial cell expression of the genes encoding the two VEGF receptors, kinase insert domain-containing receptor and fms-like tyrosine kinase 1, remained unchanged by the AGE treatment. Immunoprecipitation analysis revealed that AGE-BSA did increase de novo synthesis of VEGF. (2) Monoclonal antibody against human VEGF completely neutralized both the AGE-induced DNA synthesis and tube formation of the endothelial cells. The results suggest that AGE can elicit angiogenesis through the induction of autocrine vascular VEGF, thereby playing an active part in the development and progression of diabetic microangiopathies.

Increased secretion of TNF-alpha by costimulation of mast cells via CD28 and Fc epsilon RI

The present study unequivocally demonstrated the expression of CD28 on murine bone marrow-derived cultured mast cells and a mast cell line, MCP-5. Stimulation of surface CD28 molecules on mast cells with anti-CD28 mAbs induced tyrosine phosphorylation of cellular proteins, including several protein tyrosine kinases and their substrates, such as Itk/Emt (Emt), Btk, Syk, c-Cbl, Shc, and Vav. CD28-stimulated tyrosine phosphorylation was followed by a rebound hypophosphorylation. Interestingly, CD28 stimulation alone elicited a low level secretion of TNF-alpha. On the other hand, cross-linking of the high affinity IgE receptor (Fc epsilon RI) on mast cells induces a set of activation events, i.e., degranulation, secretion of eicosanoids, secretion of cytokines, and DNA synthesis. Concurrent stimulation of mast cells through CD28 enhanced Fc epsilon RI-induced TNF-alpha secretion in a dose-dependent manner. Together, the present data suggest a role for CD28-mediated costimulation of mast cells in the initiation and progression of allergic responses and other diseases.

Increased secretion of TNF-alpha by costimulation of mast cells via CD28 and Fc epsilon RI

The present study unequivocally demonstrated the expression of CD28 on murine bone marrow-derived cultured mast cells and a mast cell line, MCP-5. Stimulation of surface CD28 molecules on mast cells with anti-CD28 mAbs induced tyrosine phosphorylation of cellular proteins, including several protein tyrosine kinases and their substrates, such as Itk/Emt (Emt), Btk, Syk, c-Cbl, Shc, and Vav. CD28-stimulated tyrosine phosphorylation was followed by a rebound hypophosphorylation. Interestingly, CD28 stimulation alone elicited a low level secretion of TNF-alpha. On the other hand, cross-linking of the high affinity IgE receptor (Fc epsilon RI) on mast cells induces a set of activation events, i.e., degranulation, secretion of eicosanoids, secretion of cytokines, and DNA synthesis. Concurrent stimulation of mast cells through CD28 enhanced Fc epsilon RI-induced TNF-alpha secretion in a dose-dependent manner. Together, the present data suggest a role for CD28-mediated costimulation of mast cells in the initiation and progression of allergic responses and other diseases.

Expression of prolactin gene in mouse placenta during late pregnancy: detection of mRNA and its translation product

To examine the existence of PRL messenger ribonucleic acid (mRNA) in the mouse placenta during late pregnancy, reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot analysis were carried out followed by nucleotide sequence analysis of cDNA. Total RNA extracted from each tissue was reverse-transcribed, followed by PCR with two oligonucleotide primers specific or a part of mouse PRL (mPRL) cDNA. An amplified RT-PCR product of predicted size was detected in all samples from the placenta of days 16 and 18 pregnant mice. This product was specifically hybridized with a probe overlapping an entire sequence of mPRL cDNA in Southern blot analysis. Nucleotide sequence analysis also provided evidence that the amplified cDNA had a nucleotide sequence completely identical to the mPRL cDNA sequence reported previously. Furthermore, mPRL with a slightly bigger molecular weight than that of pituitary PRL was detected in the placenta of days 12, 14, 16 and 18 pregnancy by immunoblot analysis. These results suggest that PRL mRNA and its translation product are synthesized in mouse placenta during late pregnancy.

Bond-specific chemical cleavages of peptides and proteins with perfluoric acid vapors: novel peptide bond cleavages of glycyl-threonine, the amino side of serine residues and the carboxyl side of aspartic acid residues

Peptide bond cleavages by vapors composed of various from aqueous solutions of perfluoric acid were studied using synthetic peptides and proteins, and specific conditions were established for peptide bond cleavages including a novel cleavage of the glycyl-threonine bond. The peptide bonds on the aminosides of serine residues were cleaved by exposure to a vapor of 75% aqueous heptafluorobutyric acid at 30 or 50 degrees C for 24 h. Glycyl-threonine peptide bonds were cleaved with vapors of various concentrations (5, 75, and 90%) of heptafluorobutyric acid at 30-40 degrees C for 24 h. The peptide bonds on the carboxylsides of aspartic acid residues were cleaved by exposure to a vapor of 0.2% heptafluorobutyric acid at 90 degrees C for 4 to 24 h. The same vapor cleaved aspartyl-proline bonds under milder conditions such as at 60 degrees C for 16 h, under which the other aspartyl bonds were uncleaved. These specific chemical cleavages were applied to several proteins including newly characterized proteins.

[The study of urgent pulmonary resections for lung cancer accompany with pneumonia]

We studied 10 lung cancer patients with pneumonia insusceptible of conservative treatment. All patients underwent urgent pulmonary resection to control their pneumonia induced by the tumor and to cure the cancer. The causes of pneumonia were bronchial obstruction by the tumor itself or aspiration of the tumor necrosis. The patients comprised 9 men and 1 women. The age range was 37 to 72 years with a median age of 57 years. There were obstructive pneumonia in 3 patients and aspiration pneumonia in 7 cases. The average size of tumor was about 4.7 and 7.5 cm, respectively. The histological type of lung cancer was squamous cell carcinoma in 6 and adenocarcinoma in 4. There were 1 stage 1,1 stage IIIA and 3 stage IIIB tumors. Lobectomy was performed in 8 patients and pneumonectomy in 2 patients. Nine patients underwent the operation under one-lung ventilation. A median period of preoperative administration of antibiotics was 6.2 days. The curative operation for lung cancer was performed in 3 patients and non-curative operation in 7 patients. Postoperative complications were pneumonia in 2, subcutaneous abscess in 2 and arrhythmia in a case of pneumonectomy. All non-curative patients died in 5 years, but two curative patients survived long time for 31 and 75 months, respectively. We performed urgent pulmonary resection for lung cancer patients to cure fatal pneumonia and cancer. There were no hospital death. Urgent pulmonary resection could prevent early death caused by fatal pneumonia by tumor itself.

Immunoelectron microscopic demonstration of regulated pathway for calcitonin and constitutive pathway for carcinoembryonic antigen in the same cells of human medullary carcinomas of thyroid glands

The human medullary carcinomas are well known to secrete calcitonin (CT) as a neuroendocrine peptide and carcinoembryonic antigen (CEA) as a serum protein that is integrated into the cell membrane. This ultrastructural study is designed to elucidate whether CT and CEA are secreted via two different intracellular secretory pathways, a regulated pathway and a constitutive pathway. The immunoelectron microscopic postembedding method, performed on four cases of the human medullary carcinomas of the thyroid using plastic embedding material, disclosed two distinct different localization patterns for CT and CEA. CT was localized exclusively in dense cored secretory granules. CEA was present in the cell membrane and in the secretory vesicles. The secretory granules were completely negative for CEA. The trans-Golgi networks were also positive for CT and CEA. Electron microscopic double staining confirmed these localization in the same carcinoma cells. These observations suggest the presence of two distinct pathways in the endocrine cancer cells, i.e., the regulated pathway for CT and the constitutive pathway for CEA.

Tec family protein-tyrosine kinases and pleckstrin homology domains in mast cells

Tec family protein-tyrosine kinases (PTKs) have been recognized as a distinct subfamily for only a few years. Two of them, Btk and Emt, are tyrosine-phosphorylated and enzymatically activated upon cross-linking of the high-affinity IgE receptor (Fc epsilonRI), suggesting their involvement in mast cell activation. Since Lyn and other Src family PTKs phosphorylate Btk at Tyr-551 and activate the latter kinase, the receptor-associated Lyn seems to activate Btk in mast cells. The Btk kinase activity, on the other hand, is regulated negatively by phosphorylation by protein kinase C (PKC) that is associated with Btk via Btk's pleckstrin homology (PH) domain. PH domains also bind to phospholipids and the beta subunit of heterotrimeric GTP-binding proteins. Therefore, it has been hypothesized that PH domains play roles in membrane localization.

Effects of radical polymerizable spirocyclic monomers with new polymerization initiator systems on adhesion

To develop a non-polymerization shrinkage adhesive resin, the effects of the contents varying 0-20 wt% radical polymerizable spirocyclic monomers of 2-methylene-1, 4, 6-trioxyaspiro [4, 6] undecane (MTSU) and 2-methylene-8, 9-benzo-1, 4, 6 trioxyaspiro [4, 4] nonane (BTSN) together with three kinds of initiator systems in adhesive resin on bonding to both Ni-Cr alloy and unetched enamel were investigated. Tensile bond strength to either Ni-Cr alloy or unetched enamel was affected by the inclusion of MTSU or BTSN, and indicated that increased contents of MTSU or BTSN resulted in decreased bond strength to the metal in the negative correlations. Regarding the bond strength to Ni-Cr alloy, however, the effective concentration of BTSN was found to be 5 wt%, and the mean bond strength was 58.5 and 58.6 MPa, respectively. The data of differential scanning calorimeter measurement, on the other hand, showed that the copolymerization of MTSU with conventional methacrylate monomers was not completely achieved.