Na+-Ca2+ exchanger modulates Ca2+ content in intracellular Ca2+ stores in rat osteoblasts

Na+ -Ca2+ exchanger (NCX) transports Ca2+ coupled with Na+ across the plasma membrane in a bi-directional mode. Ca2+ flux via NCX mediates osteogenic processes, such as formation of extracellular matrix proteins and bone nodules. However, it is not clearly understood how the NCX regulates cellular Ca2+ movements in osteogenic processes. In this study, the role of NCX in modulating Ca2+ content of intracellular stores ([Ca2+](ER)) was investigated by measuring intracellular Ca2+ activity in isolated rat osteoblasts. Removal of extracellular Na+ elicited a transient increase of intracellular Ca2+ concentration ([Ca2+](i)). Pretreatment of antisense oligodeoxynucleotide (AS) against NCX depressed this transient Ca2+ rise and raised the basal level of [Ca2+](i). In AS-pretreated cells, the expression and activity of alkaline phosphatase (ALP), an osteogenic marker, were decreased. However, the cell viability was not affected by AS-pretreatment. Suppression of NCX activity by the AS-pretreatment decreased ATP-activated Ca2+ release from intracellular stores and significantly enhanced Ca2+ influx via store operated calcium influx (SOCI), compared to those of S-pretreated or control cells. These results strongly suggest that NCX has a regulatory role in cellular Ca2+ pathways in osteoblasts by modulating intracellular Ca2+ content.

Identification of a novel murine organic anion transporter like protein 1 (OATLP1) expressed in the kidney

The organic anion transporters (OATs) are expressed in various tissues, primarily in the kidney and liver, but they are also expressed in the placenta, small intestine, and the choroid plexus, which are all epithelial tissues that transport xenobiotics. Six isoforms of OATs are currently known. Considering the variety of organic anionic compounds, other OATs isoforms can be assumed. In this connection, we have searched for a new isoform in the expressed sequence tag (EST) database. We found the new candidate clone AK052752 in the mouse kidney cDNA library and we named it mouse organic anion transporter like protein 1 (mOATLP1). The mOATLP1 cDNA consisted of 2221 base pairs that encoded a 552 amino acid residue protein with 12 putative transmembrane domains. The deduced amino acid sequence of mOATLP1 showed 37 to 63% identity to other members of the OAT family. According to the tissue distribution based on Northern blot analysis, 2.7 kb and 2.9 kb mOATLP1 transcripts (approximate sizes) were observed in the kidney and liver. An 85-kDa band (approximate) was detected using Western blot analysis of mouse kidney performed with a synthesized oligopeptide-induced mOATLP1 antibody. Immunohistochemical results showed mOATLP1 was stained in the blood vessels, glomeruli (the parietal epithelial cells and podocytes), distal convoluted tubules, connecting tubules, and inner medullary collecting tubules. mOATLP1 appears to be a novel candidate for an organic anion transporter isoform identified in the kidney.

Evidence for Cyclooxygenase-2 Association with Caveolin-3 in Primary Cultured Rat Chondrocytes

The purpose of this study was to demonstrate the cellular localization of cyclooxygenase-2 (COX-2) and caveolin-3 (Cav-3) in primarily cultured rat chondrocytes. In normal rat chondrocytes, we observed relatively high levels of Cav-3 and a very low level of COX-2 mRNA and protein. Upon treating the chondrocytes with 5 microM of CdCl2 (Cd) for 6 hr, the expressions of COX-2 mRNA and protein were increased with the decreased Cav-3 mRNA and protein expressions. The detergent insoluble caveolae-rich membranous fractions that were isolated from the rat chondrocytes and treated with Cd contained the both proteins of both COX-2 and Cav-3 in a same fraction. The immuno-precipitation experiments showed complex formation between the COX-2 and Cav-3 in the rat chondrocytes. Purified COX-2 with glutathione S-transferase-fused COX-2 also showed complex formation with Cav-3. Confocal and electron microscopy also demonstrated the co-localization of COX-2 and Cav-3 in the plasma membrane. The results from our current study show that COX-2 and Cav-3 are co-localized in the caveolae of the plasma membrane, and they form a protein-protein complex. The co-localization of COX-2 with Cav-3 in the caveolae suggests that the caveolins might play an important role for regulating the function of COX-2.

Calcium sensing receptor forms complex with and is up-regulated by caveolin-1 in cultured human osteosarcoma (Saos-2) cells

The calcium sensing receptor (CaSR) plays an important role for sensing local changes in the extracellular calcium concentration ([Ca2+]o) in bone remodeling. Although the function of CaSR is known, the regulatory mechanism of CaSR remains controversial. We report here the regulatory effect of caveolin on CaSR function as a process of CaSR regulation by using the human osteosarcoma cell line (Saos-2). The intracellular calcium concentration ([Ca2+]i) was increased by an increment of [Ca2+]o. This [Ca2+]i increment was inhibited by the pretreatment with NPS 2390, an antagonist of CaSR. RT-PCR and Western blot analysis of Saos-2 cells revealed the presence of CaSR, caveolin (Cav)-1 and -2 in both mRNA and protein expressions, but there was no expression of Cav-3 mRNA and protein in the cells. In the isolated caveolae-rich membrane fraction from Saos-2 cells, the CaSR, Cav-1 and Cav-2 proteins were localized in same fractions (fraction number 4 and 5). The immuno-precipitation experiment using the respective antibodies showed complex formation between the CaSR and Cav-1, but no complex formation of CaSR and Cav-2. Confocal microscopy also supported the co-localization of CaSR and Cav-1 at the plasma membrane. Functionally, the [Ca2+]o- induced [Ca2+]i increment was attenuated by the introduction of Cav-1 antisense oligodeoxynucleotide (ODN). From these results, in Saos-2 cells, the function of CaSR might be regulated by binding with Cav-1. Considering the decrement of CaSR activity by antisense ODN, Cav-1 up-regulates the function of CaSR under normal physiological conditions, and it may play an important role in the diverse pathophysiological processes of bone remodeling or in the CaSR- related disorders in the body.

Clinical Features and Management of Dizziness in the Aged

BACKGROUND: Vertigo in the aged is relatively common but only a few studies are available. The purpose of this study is to analyze the clinical features and treatment outcome in aged patients. METHOD: A total of 240 patients of age over 70 with vertigo or dizziness who visited dizziness center of a tertiary care university hospital from January 1999 to January 2003 were studied. The patients' charts were retrospectively reviewed. Thorough otolaryngologic and neurotologic evaluations were performed in every case to determine the specific cause of dizziness. Electronystagmogram, rotating chair testing, and posturography were performed on all patients. The intensity of vertigo or dizziness was evaluated by questionnaires before and after the treatment. General vestibular rehabilitation therapy(VRT) was performed in 103 cases and it was not done on the other 46 cases. All the patients were treated with Ginko biloba. RESULTS: The average age was 76.5+/-6.2(70~88) years. In 153 case(63%), no specific causes for the vertigo or dizziness were found. The VRT group showed significant improvement in vertigo or dizziness compared to the non-VRT group by the VAS(verbal analogue scale) and ABC(Activities specific balance confidence scale) obtained three weeks and three months after the initiation of VRT. CONCLUSION: Many elderly patients with dizziness do not show any specific causes of dizziness other than old age(presbyastasis). General VRT seems to be effective treatment for this elderly group in addition to Ginkgo Biloba.

Clinical Features and Management of Dizziness in the Aged

BACKGROUND: Vertigo in the aged is relatively common but only a few studies are available. The purpose of this study is to analyze the clinical features and treatment outcome in aged patients. METHOD: A total of 240 patients of age over 70 with vertigo or dizziness who visited dizziness center of a tertiary care university hospital from January 1999 to January 2003 were studied. The patients' charts were retrospectively reviewed. Thorough otolaryngologic and neurotologic evaluations were performed in every case to determine the specific cause of dizziness. Electronystagmogram, rotating chair testing, and posturography were performed on all patients. The intensity of vertigo or dizziness was evaluated by questionnaires before and after the treatment. General vestibular rehabilitation therapy(VRT) was performed in 103 cases and it was not done on the other 46 cases. All the patients were treated with Ginko biloba. RESULTS: The average age was 76.5+/-6.2(70~88) years. In 153 case(63%), no specific causes for the vertigo or dizziness were found. The VRT group showed significant improvement in vertigo or dizziness compared to the non-VRT group by the VAS(verbal analogue scale) and ABC(Activities specific balance confidence scale) obtained three weeks and three months after the initiation of VRT. CONCLUSION: Many elderly patients with dizziness do not show any specific causes of dizziness other than old age(presbyastasis). General VRT seems to be effective treatment for this elderly group in addition to Ginkgo Biloba.

H2O2 Enhances Ca2+ Release from Osteoblast Internal Stores

The physiological activity of osteoblasts is known to be closely related to increased intracellular Ca2+ activity ([Ca2+]i) in osteoblasts. The cellular regulation of [Ca2+]i in osteoblasts is mediated by Ca2+ movements associated with Ca2+ release from intracellular Ca2+ stores, and transmembrane Ca2+ influx via Na+-Ca2+ exchanger, and Ca2+ ATPase. Reactive oxygen species, such as H2O2, play an important role in the regulation of cellular functions, and act as signaling molecules or toxins in cells. In this study, we investigated the effects of H2O2 on cellular Ca2+ regulation in osteoblasts by measuring intracellular Ca2+ activities using cellular calcium imaging techniques. Osteoblasts were isolated from the femurs and tibias of neonatal rats, and cultured for 7 days. The cultured osteoblasts were loaded with a Ca2+-sensitive fluorescent dye, Fura-2, and fluorescence images were monitored using a cooled CCD camera, and subsequently analyzed using image analyzing software. The results obtained are as follows: (1) The osteoblasts with lower basal Ca2+ activities yielded a transient Ca2+ increase, a Ca2+ spike, while osteoblasts with higher basal Ca2+ activities showed a continuous increase in [Ca2+]i leading to cell death. (2) Ca2+ spikes, generated after removing Na+ from superfusing solutions, were blocked by H2O2 and this was followed by a sustained increase in Ca2+ activity. (3) ATP- induced Ca2+ spikes were inhibited by pretreating with H2O2 and this was followed by a continuous increase of [Ca2+]i. When cells were pretreated with the exogenous nitric oxide (NO) donor S-Nitroso-N-acetylpenicilance (SNAP, 50 microM), treatments of ATP (1 mM) induced a Ca2+ spike-like increase, but [Ca2+]i did not return to the basal level. (4) The expression of inositol- 1,4,5-triphosphate receptor (IP3R) was enhanced by H2O2. Our results suggest that H2O2 modulates intracellular Ca2+ activity in osteoblasts by increasing Ca2+ release from the intracellular Ca2+ stores.

A case of aplastic anemia after habitual sniffing of glue and volatile substances / 대한내과학회지

The inhalation of volatile substances has becoming a popular fad among adolescents in the world. Glue sniffing is associated with injury of nervous system, liver and kidney. And rarely abnormality of blood and bone marrow suppression can develop. The main components of volatile substances that cause hematologic abnormality is thought to be benzene, toluene, and xylene. A 24 year-old male was admitted to our hospital due to gum bleeding. He was a chronic glue and organic solvents sniffer for 6 years, and quit sniffing 1 year before admission. He had no specific drug history. On admission, CBC was as follows: WBC 2,500/mm3; hemoglobin 8.9g/dl; hematocrit 25.1%; platelet 2,000/mm3. Bone marrow biopsy showed severe hypocellular marrow compatible with aplastic anemia. We report a case of aplastic anemia after habitual sniffing of glue and volatile substances with brief review of the literature.

Chylous Ascites in a Patient Undergoing Continuous Ambulatory Peritoneal Dialysis / 대한신장학회잡지

Chylous ascites is extravasation of lymphatic fluid and retention in the peritoneal cavity due to traurna or obstruction of the lymphatic system. Chylous ascites is very rare complication of Continuous Ambulatory Peritoneal Dialysis (CAPD) and is associated with trauma to the lymphatics during catheter insertion in the early stage of CAPD and repeated mild trauma to the lyrnphatics during longterm dialysis. Chylous ascites in the CAPD is suspected when the drained peritoneal fluid is milky white and confirmed by demonstration of the specific components of chyle, such as elevated triglyceride and low cholesterol than plasma and should be differentiated from pseudochyle and bacterial peritonitis. We report a case of chylous ascites in a patient undergoing CAPD at 2 months later of initiation of CAPD, which was not improved by conservative management. So CAPD catheter was removed and renal replacement therapy was changed to hemodialysis.

A Case of Adenocarcinoma of the Lung In Patient with Chronic Lymphpcoytic Leukemia / 대한암학회지

In Korea chronic lymphocytic leukemia(CLL) is a rare diesase with evidence immunologic incompetence. The immunodeficiency of patients with CLL could place them at increased risk of new cancers. The incidence of secondary malignancy, including lung cancer has increased in patients with CLL and this should be also considered in the differential diagnosis of a new pulmonary infiltrate appearing in patients with known CLL. A-73-year old male patient with CLL was admitted to our hospital because of dyspnea. Chest X-ray showed multiple scattered small nodules in both lung fields and alveolar consolidation mass at right lower lung. Histopathological examination of the bronchoscopic biopsy specimen demonstrated that he had a moderatly differentiated adenacarcinoma of lung. Since we experienced a case of metachronous adenocarcinoma of lung in patient with known CLL, we report this with a review of literatures.