Nicotine- and tar-free cigarette smoke induces cell damage through reactive oxygen species newly generated by PKC-dependent activation of NADPH oxidase

We examined cytotoxic effects of nicotine/tar-free cigarette smoke extract (CSE) on C6 glioma cells. The CSE induced plasma membrane damage (determined by lactate dehydrogenase leakage and propidium iodide uptake) and cell apoptosis {determined by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] reduction activity and DNA fragmentation}. The cytotoxic activity decayed with a half-life of approximately 2 h at 37°C, and it was abolished by N-acetyl-L-cysteine and reduced glutathione. The membrane damage was prevented by catalase and edaravone (a scavenger of (•)OH) but not by superoxide dismutase, indicating involvement of (•)OH. In contrast, the CSE-induced cell apoptosis was resistant to edaravone and induced by authentic H(2)O(2) or O(2)(-) generated by the xanthine/xanthine oxidase system, indicating involvement of H(2)O(2) or O(2)(-) in cell apoptosis. Diphenyleneiodonium [NADPH oxidase (NOX) inhibitor] and bisindolylmaleimide I [BIS I, protein kinase C (PKC) inhibitor] abolished membrane damage, whereas they partially inhibited apoptosis. These results demonstrate that 1) a stable component(s) in the CSE activates PKC, which stimulates NOX to generate reactive oxygen species (ROS), causing membrane damage and apoptosis; 2) different ROS are responsible for membrane damage and apoptosis; and 3) part of the apoptosis is caused by oxidants independently of PKC and NOX.

Function and regulation of endothelin type A receptor-operated transient receptor potential canonical channels

The purpose of this study is to identify transient receptor potential canonical (TRPC) channels responsible for receptor-operated Ca(2+) entry (ROCE) triggered by activation of endothelin type A receptor (ET(A)R) and to clarify the importance of calmodulin (CaM) / inositol 1,4,5-trisphosphate (IP(3)) receptor binding (CIRB) domain at the C terminus of TRPC channels in ET(A)R-activated channel regulation. In HEK293 cells coexpressing ET(A)R and one of seven TRPC isoforms, ET(A)R stimulation induced ROCE through TRPC3, TRPC5, TRPC6, and TRPC7. The TRPC3- and TRPC6-mediated ROCE was inhibited by selective inhibitors of G(q) protein, phospholipase C (PLC), and CaM. The CIRB domain deletion mutants of TRPC3 and TRPC6 failed to induce ET(A)R-mediated ROCE. Either deletion of the CIRB domain or pharmacological inhibition of CaM did not inhibit the targeting of these channels to the plasma membrane. These results suggest that 1) TRPC3, TRPC5, TRPC6, and TRPC7 can function as ET(A)R-operated Ca(2+) channels; 2) G(q) protein, PLC, and CaM are involved in TRPC3- and TRPC6-mediated ROCE; 3) ET(A)R-mediated activation of TRPC3 and TRPC6 requires the CIRB domain; and 4) abolition of ET(A)R-induced ROCE by CIRB domain deletion and CaM inhibition is due to loss of CaM binding to the channels but not loss of cell surface TRPC3 and TRPC6.

Adenylate cyclase/cAMP/protein kinase A signaling pathway inhibits endothelin type A receptor-operated Ca²⁺ entry mediated via transient receptor potential canonical 6 channels

Receptor-operated Ca²⁺ entry (ROCE) via transient receptor potential canonical channel 6 (TRPC6) is important machinery for an increase in intracellular Ca²⁺ concentration triggered by the activation of G(q) protein-coupled receptors. TRPC6 is phosphorylated by various protein kinases including protein kinase A (PKA). However, the regulation of TRPC6 activity by PKA is still controversial. The purpose of this study was to elucidate the role of adenylate cyclase/cAMP/PKA signaling pathway in the regulation of G(q) protein-coupled endothelin type A receptor (ET(A)R)-mediated ROCE via TRPC6. For this purpose, human embryonic kidney 293 (HEK293) cells stably coexpressing human ET(A)R and TRPC6 (wild type) or its mutants possessing a single point mutation of putative phosphorylation sites for PKA were used to analyze ROCE and amino acids responsible for PKA-mediated phosphorylation of TRPC6. Ca²⁺ measurements with thapsigargin-induced Ca²⁺-depletion/Ca²⁺-restoration protocol to estimate ROCE showed that the stimulation of ET(A)R induced marked ROCE in HEK293 cells expressing TRPC6 compared with control cells. The ROCE was inhibited by forskolin and papaverine to activate the cAMP/PKA pathway, whereas it was potentiated by Rp-8-bromoadenosine-cAMP sodium salt, a PKA inhibitor. The inhibitory effects of forskolin and papaverine were partially cancelled by replacing Ser28 (TRPC6(S28A)) but not Thr69 (TRPC6(T69A)) of TRPC6 with alanine. In vitro kinase assay with Phos-tag biotin to determine the phosphorylation level of TRPC6 revealed that wild-type and mutant (TRPC6(S28A) and TRPC6(T69A)) TRPC6 proteins were phosphorylated by PKA, but the phosphorylation level of these mutants was lower (approximately 50%) than that of wild type. These results suggest that TRPC6 is negatively regulated by the PKA-mediated phosphorylation of Ser28 but not Thr69.

Recanalisation of the internal carotid artery via the vasa vasorum after coil occlusion

Antegrade recanalisation of a completely occluded internal carotid artery (ICA) via the vasa vasorum is extremely rare. Here, we report such a case after proximal endovascular coiling in a case of dissected (i.e. non-atherosclerotic) ICA. A 42-year-old man presented with thromboembolic stroke of the left frontal lobe owing to pseudo-occlusion of the left ICA manifesting as motor aphasia and right hemiparesis. There were abundant floating thrombi in the petrous portion of the left ICA. Because of good collateral flow in the left middle cerebral artery territory through the anterior communicating artery and external carotid artery system, endovascular coil embolisation of the left ICA was performed for prevention of further thromboembolic stroke. The patient showed progressive recovery following endovascular treatment, and was discharged with mild right hemiparesis 1 month later. He maintained a regimen of aspirin and physical rehabilitation. At follow-up, 38 months later, the patient was asymptomatic. Angiography demonstrated occlusion of the left ICA and multiple serpiginous vessels originating from the proximal internal and external carotid arteries and which filled the ICA distal to the occlusion. This case suggests that an ICA occluded by proximal coil embolisation-even in a non-atherosclerotic case-might be recanalised via the vasa vasorum.

SMOC1 is essential for ocular and limb development in humans and mice

Microphthalmia with limb anomalies (MLA) is a rare autosomal-recessive disorder, presenting with anophthalmia or microphthalmia and hand and/or foot malformation. We mapped the MLA locus to 14q24 and successfully identified three homozygous (one nonsense and two splice site) mutations in the SPARC (secreted protein acidic and rich in cysteine)-related modular calcium binding 1 (SMOC1) in three families. Smoc1 is expressed in the developing optic stalk, ventral optic cup, and limbs of mouse embryos. Smoc1 null mice recapitulated MLA phenotypes, including aplasia or hypoplasia of optic nerves, hypoplastic fibula and bowed tibia, and syndactyly in limbs. A thinned and irregular ganglion cell layer and atrophy of the anteroventral part of the retina were also observed. Soft tissue syndactyly, resulting from inhibited apoptosis, was related to disturbed expression of genes involved in BMP signaling in the interdigital mesenchyme. Our findings indicate that SMOC1/Smoc1 is essential for ocular and limb development in both humans and mice.

Usefulness of endoscopic retrograde biliary biopsy using large-capacity forceps for extrahepatic biliary strictures: a prospective randomized study

BACKGROUND AND STUDY AIMS

Endoscopic retrograde biliary biopsy samples are frequently too small and inadequate, which makes histological interpretation difficult. We therefore evaluated the diagnostic usefulness of forceps with a larger-sized cup and compared this with standard forceps for biliary biopsy.

PATIENTS AND METHODS

This prospective study included consecutive patients with extrahepatic biliary strictures who underwent retrograde biliary biopsy between March 2005 and March 2006 at the Toho University Ohashi Medical Center. The standard forceps used were 1.8-mm forceps (FB-39Q, Olympus, Tokyo, Japan) and the large-capacity forceps were 2.2-mm forceps (Radial jaw3, Boston Scientific Inc., Natick, Massachusetts, USA). Four randomized biopsy specimens were taken from each patient, two using each type of forceps.

RESULTS

A total of 32 patients (30 with malignant biliary strictures and 2 with benign biliary strictures) were enrolled. The median size of the biopsy samples taken using the standard forceps was 0.68 mm (2) and that using the large-capacity forceps was 1.98 mm (2) ( P < 0.0001). Significant differences between the standard forceps and large-capacity forceps were observed in sensitivity (43 % vs. 70 %), adequacy of the specimens, and submucosal tissue sampling rate.

CONCLUSIONS

Large-capacity forceps performed better than standard forceps in terms of size, adequacy of the sample, submucosal sampling rate, and detection of neoplasia.

Sumoylation controls retinal progenitor proliferation by repressing cell cycle exit in Xenopus laevis

Precisely controlled progenitor proliferation is essential for normal development. However, molecular mechanisms, which control the correct timing of cell cycle withdrawal during development, have been poorly understood. We show here that ubc9, a sumo-conjugating enzyme, controls the cell cycle exit of retinal progenitors. We found that ubc9 is highly expressed in retinal progenitors and stem cells in Xenopus embryos. Ubc9 physically and functionally associates with Xenopus hmgb3, which is required for retinal cell proliferation, and prolonged expression of ubc9 and hmgb3 results in suppression of the cell cycle exit of retinal progenitors in a sumoylation-dependent manner. Overexpression of ubc9 and hmgb3 decreased expression of the cell-cycle inhibitor p27(Xic1). Furthermore, progenitor proliferation is regulated, at least in part, by sumoylation of transcription factor Sp1. These results suggest a significant role of sumoylation for cell cycle regulation in retinal progenitors.

The change in characteristics of microcrystalline cellulose during wet granulation using a high-shear mixer

The objective of this study was to investigate the mechanism of hard granule formation and to demonstrate the applicability of X-ray diffraction methods for studying the polymeric pharmaceutical excipients. Using a high-shear mixer, microcrystalline cellulose (MCC) was granulated with water as the granulating liquid. The hardness of the MCC granules increased with granulation time and the amount of water added. The specific surface area measured by the N2 adsorption method was reduced during the process. Crystallite size of cellulose, calculated by Scherrer's equation adapted for wide angle X-ray diffraction method, decreased with granulation time and with increasing amounts of water added. Debye plots for X-ray small scattering patterns suggested that the average magnitude of the continuous solid region in MCC granules became significantly greater, whereas the specific surface area of the MCC granules, calculated from Debye plots, became smaller in comparison with that of intact MCC. These findings suggested that the long-chain structures in MCC were disrupted, resulting in smaller units with shorter chain lengths due to the strong shear force of the impeller. These smaller units then form a network within the granules. Thus, MCC granules are strengthened with longer granulation time and greater amounts of water, resulting in a more intricate network. The change in MCC chain length and physical structure can be experimentally detected using the small-angle X-ray scattering and wide-angle powder X-ray diffraction methods.

Secreted factor FAM3C (ILEI) is involved in retinal laminar formation

FAM3C is a secreted factor, which is involved in the epithelial to mesenchymal transition. In transcriptome profiling of the mouse retina using microarray, we found that FAM3C is highly expressed in the retina. FAM3C is expressed in the ganglion cell layer (GCL) of the retina. To explore the function of FAM3C in retinal development, we cloned Xenopus FAM3C (XFAM3C), and performed Xenopus gain- and loss-of-function analysis. Overexpression of XFAM3C resulted in retinal laminar disorganization and an increase in eye size. Loss of function experiments of XFAM3C using antisense morpholino oligonucleotides caused photoreceptor cell dislocation. Cellular differentiation was not affected by either gain- or loss-of-function experiments of XFAM3C. These findings suggest that FAM3C is involved in retinal laminar formation processes in vertebrates.

Isolation and characterization of a novel plasma membrane protein, osteoblast induction factor (obif), associated with osteoblast differentiation

BACKGROUND

While several cell types are known to contribute to bone formation, the major player is a common bone matrix-secreting cell type, the osteoblast. Chondrocytes, which plays critical roles at several stages of endochondral ossification, and osteoblasts are derived from common precursors, and both intrinsic cues and signals from extrinsic cues play critical roles in the lineage decision of these cell types. Several studies have shown that cell fate commitment within the osteoblast lineage requires sequential, stage-specific signaling to promote osteoblastic differentiation programs. In osteoblastic differentiation, the functional mechanisms of transcriptional regulators have been well elucidated, however the exact roles of extrinsic molecules in osteoblastic differentiation are less clear.

RESULTS

We identify a novel gene, obif (osteoblast induction factor), encoding a transmembrane protein that is predominantly expressed in osteoblasts. During mouse development, obif is initially observed in the limb bud in a complementary pattern to Sox9 expression. Later in development, obif is highly expressed in osteoblasts at the stage of endochondral ossification. In cell line models, obif is up-regulated during osteoblastic differentiation. Exogenous obif expression stimulates osteoblastic differentiation and obif knockdown inhibits osteoblastic differentiation in preosteblastic MC3T3-E1 cells. In addition, the extracellular domain of obif protein exhibits functions similar to the full-length obif protein in induction of MC3T3-E1 differentiation.

CONCLUSIONS

Our results suggest that obif plays a role in osteoblastic differentiation by acting as a ligand.

Endovascular treatment of aneurysmal subarachnoid hemorrhage associated with bilateral common carotid artery occlusion

SUMMARY

Cases of aneurysm associated with the occlusion of both common carotid arteries are very rare.We present a case of ruptured aneurysms of the basilar bifurcation and posterior cerebral artery coexisting with bilateral common carotid artery occlusion, successfully treated by endovascular coil embolization with a double-balloon remodeling technique. Finally, we review the literature. A 62-year-old woman presented with severe headache; a computed tomography scan demonstrated subarachnoid hemorrhage. Angiography revealed that the bilateral common carotid arteries were occluded. The muscle branches of the vertebral arteries had anastomosed to the bilateral external carotid arteries. Bilateral posterior communicating arteries had developed and supplied the bilateral internal carotid arteries. Two aneurysms (a saccular aneurysm of the P1 portion of the left posterior cerebral artery and a wide-necked aneurysm of the basilar bifurcation) were also observed. Endovascular embolization of the aneurysms was successfully performed using a double-balloon remodeling technique. The patient made a full recovery after treatment, and the aneurysms remained obliterated 12 months after embolization. We believe that this is the first report of ruptured aneurysms associated with bilateral common carotid artery occlusion successfully treated by endovascular coiling. The double-balloon remodeling technique was useful for treatment of wide-necked basilar bifurcation aneurysm.

Painful ophthalmoplegia caused by idiopathic hypertrophic cranial pachymeningitis in the cavernous sinus

A 73-year-old man presenting with painful unilateral ophthalmoplegia is reported. Magnetic resonance imaging demonstrated a mass in the cavernous sinus extending to the floor of the middle cranial fossa. After resection of the lesion and anti-tuberculous chemotherapy his symptoms improved. Pathological examination revealed extensive caseous necrosis.

Unusual variant of persistent primitive hypoglossal artery

Here, we present a case of an unusual variant of a persistent primitive hypoglossal artery, which was found incidentally during an examination for a hypertensive thalamic haemorrhage. The anastomotic vessel arose from the external carotid artery and joined the vertebral artery through the hypoglossal canal. The embryology of the anomaly is briefly discussed.

In vitro analysis of Bcl-2 proteins in mitochondria and endoplasmic reticulum: similarities in anti-apoptotic functions and differences in regulation

Anti-apoptotic Bcl-2 localizes in the membranes of mitochondria and endoplasmic reticulum (ER) and resists a broad range of apoptotic stimuli. However, the precise function of Bcl-2 in ER is still unclear. We herein examined the anti-apoptotic potencies of Bcl-2 in mitochondria and ER in vitro. The mitochondria isolated from HeLa cells, which have little or practically no Bcl-2, were apoptosis-competent. That is, membrane-bound Bax was activated and cytochrome c was released when the isolated mitochondria were incubated at 35 degrees C. Cytochrome c release from the apoptosis-competent mitochondria was suppressed by co-incubation with the mitochondria with overexpressed Bcl-2 (Bcl-2 mitochondria), suggesting that Bcl-2 anchored in one mitochondrion can suppress cytochrome c release from another mitochondrion. Similar results were obtained when microsomes with overexpressed Bcl-2 (Bcl-2 microsomes) were co-incubated with apoptosis-competent mitochondria. A quantitative titration analysis showed that Bcl-2 in the ER suppresses cytochrome c release as efficiently as that in the mitochondria. An immunoprecipitation assay showed that Bcl-2 in both mitochondria and ER binds to Bax at almost the same degree. However, in the presence of tBid, co-incubation of apoptosis-competent mitochondria with Bcl-2 microsomes, but not with Bcl-2 mitochondria, diminished the Bax-binding to Bcl-2 significantly, suggesting that Bcl-2 in ER is readily inactivated by tBid. Co-incubation assay further confirmed that Bcl-2 in the ER, but not Bcl-2 in the mitochondria, is potentially inactivated by tBid. Our quantitative in vitro studies indicate that Bcl-2 in mitochondria and ER are similarly potent in inhibiting Bax-associated apoptosis of other mitochondria, but are regulated by tBid differently.

Dkk3-Cre BAC transgenic mouse line: a tool for highly efficient gene deletion in retinal progenitor cells

To establish the genetic tools for conditional gene deletion in mouse retinal progenitors, we generated a Dkk3-Cre transgenic mouse line using bacterial artificial chromosome (BAC) transgenesis. Cre recombination efficiency in vivo was assayed by crossing this transgenic line, termed BAC-Dkk3-Cre, with the CAG-CAT-Z reporter line. This BAC-Dkk3-Cre line showed Cre recombinase activity in most retinal progenitors. Cre activity was detectable from embryonic day 10.5 (E10.5) and generally restricted to the retina during embryogenesis. To verify that BAC-Dkk3-Cre mice successfully circumvented lethality, we generated Otx2flox/flox/BAC-Dkk3-Cre+ mice as Otx2 conditional knockout mice. The Otx2flox/flox/BAC-Dkk3-Cre+ mice were viable, and their retina showed loss of mature cell-type markers of photoreceptor cells, bipolar cells, and horizontal cells, in contrast, amacrine-like cells noticeably increased. Thus, the BAC-Dkk3-Cre transgenic mouse line provides a powerful tool for generating conditional knockout mouse lines for studying loss of gene functions in the developing retina.