Biomedical subjects

H Sakai

Publications and source records attributed to H Sakai.

At least 397 records · Page 22Linked to original sources

PubMed1998

[Aortic and mitral valve aneurysms complicated with infective endocarditis: a case report].

A rare case of aortic and mitral valve aneurysms complicated with infective endocarditis was accurately diagnosed by transesophageal echocardiography. A 57-year-old man with severe aortic regurgitation due to infective endocarditis was admitted to our hospital. Transthoracic echocardiography showed an aortic valve aneurysm on the right coronary cusp and perforations on the other cusps. Transesophageal echocardiography demonstrated a small aneurysm on the anterior leaflet of the mitral valve which was not clearly visualized by transthoracic echocardiography. Color Doppler echocardiography revealed severe aortic regurgitation and mild mitral regurgitation without perforation of the mitral valve aneurysm. Aortic valve replacement and mitral valvuloplasty of the anterior mitral leaflet were performed. The right coronary cusp of the aortic valve showed marked thinning with infiltration of inflammatory cells. The postoperative clinical course was uneventful.

Aortic Valve↗

PubMed1998

Effect of local application of basic fibroblast growth factor on ligament healing in rabbits.

OBJECTIVE: The effect of basic fibroblast growth factor (bFGF) on healing of a 4-mm defect in the medial collateral ligament of rabbits was studied. METHODS: Fibrin gel containing 0 (vehicle only), 0.1, 1, or 10 micrograms of recombinant human bFGF was applied to the defect during the surgical procedure. Controls did not receive fibrin gel. Four rabbits in each group were sacrificed 1, 2, 3, and 6 weeks after surgery. Repair tissues were subjected to gross and histologic examinations, and expression of type I procollagen messenger RNA was evaluated using in situ hybridization after 2 and 3 weeks. RESULTS: bFGF promoted formation of repair tissue and was associated with early filling of the ligament defect. Tissue maturation was significantly delayed after 3 and 6 weeks in the high-dose bFGF groups. In the low dose group, in contrast, tissue maturation was similar to that in controls at all time points, by both gross and histologic examination. In situ hybridization studies showed that type I procollagen mRNA expression was reduced in all bFGF groups. CONCLUSION: Our data demonstrate that a single local application of bFGF promoted early formation of repair tissue in injured medial collateral ligaments. High doses of bFGF reduced repair tissue maturation, suggesting that in clinical uses the dose may play a significant role.

Animals↗

PubMed1998

[Bone metastasis of primary lung cancer].

To improve the treatment of patients with bone metastasis from lung cancer, 178 (23.8%) of 748 patients with primary lung cancer admitted to our hospital during an 11-year period were studied. The 178 patients were mainly women. The frequency of bone metastasis was significantly higher among patients with adenocarcinoma than among those with small cell or squamous cell cancer. The concentration of carcinoembryonic antigen in serum was significantly higher in patients with bone metastasis than in those with stage IV lung cancer without bone metastasis. The bone lesions were symptomatic in 116 patients (65%) and were treated in 67. Symptomatic improvement was achieved in 50 patients (74%) and pain was alleviated in 94%. However, neurological disorders improved in only 41%. Differences in survival did not depend on the presence or absence of symptomatic bone metastasis or no whether the metastases were treated. The median survival time of patients who responded to treatment tended to be longer than that of patients in whom treatment was not effective. The median survival time calculated from the start of treatment was 5 months for patients with bone metastasis and 7.3 months for patients with stage IV disease without bone metastasis. Aggressive local treatment may be effective for painful bone metastasis.

Biomarkers, Tumor↗

PubMed1998

[An autopsy case of rhino-orbito-cerebral mucormycosis associated with multiple cranial nerve palsy and subsequent subarachnoid hemorrhage].

We report an autopsy case of 53-year-old male with poor controlled diabetes mellitus and hepatocellular carcinoma who developed rhino-orbito-cerebral mucormycosis. Initial complaints were epistaxis and headache followed by a sudden blindness, the 2nd through 7th cranial nerve palsy and diabetes inspidus. Laboratory data revealed that he had liver cirrhosis due to hepatitis C virus infection and diabetes mellitus. Head CT and MRI showed no significant findings. Eleven days after the onset, he died of subarachnoid hemorrhage. The postmortem examination revealed severe infiltration of numerous mucors in the sphenoid sinus, cavernous sinus and bilateral internal carotid arteries. Severe granulomatous vasculitis was seen in the cavernous portion of the bilateral internal carotid arteries. Thus, we considered that this case had been caused by the infiltration of mucors to the cavernous sinus, resulting in the obstruction of ophthalmic arteries. Rupture of the right internal carotid artery was seen at the branching portion of the ophthalmic artery, demonstrating the cause of his death. We would like to emphasize that rhino-orbito-cerebral mucormycosis should be ruled out if we examine a nondiagnostic case of diabetes mellitus or immunosuppressed disease associated with rapid multiple cranial nerve palsy following the orbital symptoms.

Abducens Nerve↗

PubMed1998

[A case of systemic lupus erythematosus developed with intestinal perforation].

A case of intestinal perforation associated with SLE is presented. A 54-year-old woman was diagnosed as having SLE twenty-five years ago when she had facial erythema, photosensitivity, oral aphtha, polyarthraliga, leukopenia, positive LE cell and positive antinuclear antibody. She had been treated with prednisolone and admitted to Kushiro City General Hospital because of one month history of fever and anorexia in February 1996. Laboratory findings did not reveal activity of SLE, and a diagnosis of urinary tract infection was made based on the findings of urinalysis. After severe diarrhea, disseminated intravascular coagulation (DIC) developed. A rectal perforation was revealed by endoscopic and radiological examination. An emergency laparotomy revealed necrosis of the rectum and sigmoidostomy was performed. The biopsied specimen of the rectum were diagnosed as gangrene of ischemic colitis histologically. Because of a penetration to the urinary bladder, an ureterocutaneostomy was performed. She died of sepsis and DIC on the 127th day of admission. Only 11 cases of intestinal perforation associated with SLE have been reported in Japan, and the association of vasculitis has been considered. In the present case, the prolonged use of prednisolone might cause the necrotizing ischemic colitis.

Female↗

PubMed1998

Expression profile of prostate-specific antigen messenger RNA assessed by in situ hybridization is a novel prognostic marker for patients with untreated prostate cancer.

The present study was undertaken to define the relationship between histological grade (Gleason grade) and prostate-specific antigen (PSA) mRNA expression and to evaluate the level of PSA mRNA expression as a possible prognostic marker for untreated prostate cancers. The primary grade areas of 104 prostatic biopsy specimens were analyzed for the expression of PSA mRNA and its protein by nonradioactive in situ hybridization and immunohistochemistry, respectively. A multivariate survival analysis was performed to examine the correlation between PSA mRNA expression and several clinicopathological parameters, e.g., the immunostaining level of PSA protein in biopsy specimens. The percentage of specimens positive for PSA mRNA increased significantly with advanced histological grade. Image analysis of the signal intensity for PSA mRNA showed a significant correlation between the signal intensity in both primary and secondary grade areas of each specimen and the histological grade (P < 0.0001). Only 26.0% of specimens positive for PSA protein were also positive for PSA mRNA (and vice versa, 6.7%). Other tumors were either positive for both (66.3%) or negative for both (1.0%). When the Cox's proportional hazards regression model was used to analyze cancer-specific survival, untreated patients with higher levels of PSA mRNA expression in the higher grade (representing higher grade of either primary or secondary grade) area of tumors were at high risk for cancer-related death (P = 0.017). Furthermore, in cancer-specific survival curves based on PSA mRNA expression status, patients with high levels of PSA mRNA expression in the higher grade area of tumors had a significantly poorer prognosis (P = 0.001), compared with those with tumors expressing low levels of PSA mRNA. Our results suggested that analysis of PSA mRNA expression in specific areas in biopsy specimens of patients with untreated prostate cancer may provide a good assessment of prognosis of prostate cancers.

Aged↗

PubMed1998

[Usefulness of initial chemoendocrine therapy for advanced prostate cancer].

The 5 year cancer specific survival rate of advanced prostate cancer, especially in metastatic cancer is less than 40%. Recently, maximum androgen blockade showed some beneficial effects in cases of minor disease but no additional usefulness in major cases. The treatment modality referred to as initial chemoendocrine, used to treat prostate cancer, seems to be a reasonable method because prostate cancer cells contain heterogeneity. This procedure means that the endocrine treatment is best suited to treat hormone sensitive cells, whereas chemotherapy is more appropriately used as a firstline therapy for hormone insensitive cells. We reported that the initial chemoendocrine method showed superiority in the 5 year cancer specific survival category than in the endocrine therapy analyzing non-randomized trials. From that stage on we reviewed the beneficial point of the treatment, and are now trying randomized control studies.

Antineoplastic Agents↗

PubMed1998

[Detection of coronary artery disease by adenosine triphosphate stress echocardiography: comparison with adenosine triphosphate stress thallium myocardial scintigraphy and coronary angiography].

The clinical feasibility and usefulness of adenosine triphosphate-2Na (ATP) stress echocardiography for the detection of coronary artery disease (CAD) were assessed. Two-dimensional echocardiography and thallium-201 single photon emission computed tomography (SPECT) during ATP infusion were performed simultaneously in 58 consecutive patients (41 men and 17 women; mean age 66 +/- 12 years) with suspected CAD. ATP was infused intravenously at 0.16 mg/kg/min for 5 min and thallium was injected at 4 min. All patients underwent coronary angiography within 2 weeks of ATP echocardiography and ATP SPECT. An ischemic response during ATP infusion was detected by echocardiography as the development or worsening of a wall motion abnormality compared with the baseline and by SPECT as a perfusion defect that filled totally or partially during redistribution. Significant coronary artery stenosis was defined as > or = 75% diameter stenosis in a major epicardial vessel. The severity of the stenosis was classified as follows: Group A, lesions with significant coronary artery stenosis (> or = 75%, < 90%); Group B, lesions with severe coronary artery stenosis (> or = 90%) without collateral circulation; Group C, lesions with severe coronary artery stenosis (> or = 90%) with collateral circulation. Significant CAD was present in 43 of 58 patients. The overall sensitivity, specificity and accuracy of ATP echocardiography for detecting significant CAD were 70%, 100% and 78%, respectively, and those of ATP SPECT were 98%, 87% and 95%, respectively. In patients without previous myocardial infarction, the sensitivity of ATP echocardiography was 67%. The sensitivity of ATP echocardiography and ATP SPECT for detecting myocardial ischemia were 59% and 95% in patients with 1-vessel disease, 75% and 100% in those with 2-vessel disease, and 88% and 100% in those with 3-vessel disease, respectively. The induction of wall motion abnormality by ATP echocardiography was highly concordant with ATP SPECT imaging in patients with multivessel disease. Although the sensitivity of ATP echocardiography improved in patients with multivessel disease more than in those with single-vessel disease, detection of all diseased vessels was achieved in only 10% of patients with multivessel disease. The sensitivity of ATP echocardiography and ATP SPECT for detecting myocardial ischemia in individual vessels were: right coronary artery, 58% and 74%; left anterior descending artery, 59% and 97%; left circumflex artery, 27% and 68%. ATP-induced transient perfusion defects were associated with transient wall motion abnormality in only 57% of segments. The sensitivity of ATP echocardiography and ATP SPECT for detecting myocardial ischemia in patients with severe coronary stenosis were: Group A, 32% and 66%; Group B, 60% and 93%; Group C, 80% and 95%. The sensitivity of ATP echocardiography was significantly higher in the lesions with collateral circulation than in those without collateral circulation. ATP stress echocardiography is useful for detecting myocardial ischemia in patients with multivessel disease and in patients with severe coronary artery stenosis (> or = 90%). In particular, transient wall motion abnormality tends to be detected in the segments perfused by collateral circulation.

Adenosine Triphosphate↗

PubMed1998

[Clinical utility of the free prostate specific antigen (PSA), alpha 1-antichymotrypsin-complexed PSA, and free/total PSA ratio using the specific and sensitive enzyme-linked immunosorbent assay "E-plate EIKEN PSA"].

We studied the clinical significance of serum prostate specific antigen (PSA) ratio: free-PSA/total-PSA and free-PSA/complex-PSA to discriminate between prostate cancer (PC) and prostate benign disease (non-PCa) by using total-PSA, alpha 1-antichymotrypsin complexed (complex)-PSA and free-PSA enzyme-linked immunosorbent assay (ELISA) kits newly developed at EIKEN Chemical Co, Ltd. Fre-PSA and complex-PSA ELISA kits demonstrated high sensitivity and specificity. Total-PSA ELISA kit also demonstrated equimolarity for free-PSA and complex-PSA. On the total-PSA range of 4-10 ng/ml, free-PSA/total-PSA% (f/t%) and free-PSA/complex-PSA% (f/c%) were very useful to discriminate between PCa and non-PCa by receiver operating characteristic curve analysis as well as PSA density (PSA-D) but not free-PSA level. F/t% and f/c% were even useful to discriminate early stage PCa (i.e. A1 or B0) from non-PCa by the Mann-Whitney U-test.

Enzyme-Linked Immunosorbent Assay↗

PubMed1997

Immunohistochemical colocalization of glycoxidation products and lipid peroxidation products in diabetic renal glomerular lesions. Implication for glycoxidative stress in the pathogenesis of diabetic nephropathy.

Advanced glycation end products (AGEs) include a variety of protein adducts whose accumulation alters the structure and function of tissue proteins and stimulates cellular responses. They have been implicated in tissue damage associated with diabetic complications. To assess the possible link between AGE accumulation and the development of diabetic nephropathy (DN), we have examined the immunohistochemical localization of various AGE structures postulated to date, i.e., pentosidine, Nepsilon-(carboxymethyl)lysine (CML), and pyrraline, in diabetic and control kidneys. CML and pentosidine accumulate in the expanded mesangial matrix and thickened glomerular capillary walls of early DN and in nodular lesions and arterial walls of advanced DN, but were absent in control kidneys. By contrast, pyrraline was not found within diabetic glomeruli but was detected in the interstitial connective tissue of both normal and diabetic kidneys. Although the distribution of pyrraline was topographically identical to type III collagen, distribution of pentosidine and CML was not specific for collagen type, suggesting that difference in matrix protein composition per se could not explain heterogeneous AGE localization. Since oxidation is linked closely to the formation of pentosidine and CML, we also immunostained malondialdehyde (MDA), a lipid peroxidation product whose formation is accelerated by oxidative stress, assuming that local oxidative stress may serve as a mechanism of pentosidine and CML accumulation. Consistent with our assumption, diabetic nodular lesions were stained positive for MDA. These findings show that AGE localization in DN varies according to AGE structure, and suggest that the colocalization of markers of glycoxidation (pentosidine and CML) with a marker of lipid peroxidation reflects a local oxidative stress in association with the pathogenesis of diabetic glomerular lesions. Thus, glycoxidation markers may serve as useful biomarkers of oxidative damage in DN.

Adolescent↗

PubMed1997

A modulatory subunit of acid sensing ion channels in brain and dorsal root ganglion cells.

MDEG1 is a cation channel expressed in brain that belongs to the degenerin/epithelial Na+ channel superfamily. It is activated by the same mutations which cause neurodegeneration in Caenorhabditis elegans if present in the degenerins DEG-1, MEC-4, and MEC-10. MDEG1 shares 67% sequence identity with the recently cloned proton-gated cation channel ASIC (acid sensing ion channel), a new member of the family which is present in brain and in sensory neurons. We have now identified MDEG1 as a proton-gated channel with properties different from those of ASIC. MDEG1 requires more acidic pH values for activation and has slower inactivation kinetics. In addition, we have cloned from mouse and rat brain a splice variant form of the MDEG1 channel which differs in the first 236 amino acids, including the first transmembrane region. This new membrane protein, which has been called MDEG2, is expressed in both brain and sensory neurons. MDEG2 is activated neither by mutations that bring neurodegeneration once introduced in C. elegans degenerins nor by low pH. However, it can associate both with MDEG1 and another recently cloned H+-activated channel DRASIC to form heteropolymers which display different kinetics, pH dependences, and ion selectivities. Of particular interest is the subunit combination specific for sensory neurons, MDEG2/DRASIC. In response to a drop in pH, it gives rise to a biphasic current with a sustained current which discriminates poorly between Na+ and K+, like the native H+-gated current recorded in dorsal root ganglion cells. This sustained current is thought to be required for the tonic sensation of pain caused by acids.

Acid Sensing Ion Channels↗

PubMed1997

Thromboxane A2, released by the anti-tumour drug irinotecan, is a novel stimulator of Cl- secretion in isolated rat colon.

1. A camptothecin derivative, irinotecan (Cpt-11), is a topoisomerase I inhibitor and has a strong activity against a broad range of human cancer. One of the side-effects of this drug is diarrhoea. Here, we tried to determine the mediator of the irinotecan-induced Cl- secretion which may underlie this diarrhoea, using isolated mucosae of rat distal colon. 2. Irinotecan increased Cl- secretory current in a concentration-dependent manner across the mucosa, set between Ussing chambers. Thromboxane A2 (TXA2) has not been reported to date as a physiological stimulant of Cl- secretion in the distal colon. However, the major part of the present irinotecan-induced current was inhibited by selective thromboxane A2 receptor antagonists (KW-3635 and ONO-3708), and a selective thromboxane synthase inhibitor (Y-20811). In fact, we found that irinotecan stimulated the release of TXA2 in a concentration-dependent manner from the isolated mucosa into the bathing solutions. 3. Furthermore, 9,11-epithio-11,12-methano-thromboxane A2 (STA2), a stable analogue of TXA2, induced Cl- secretion, which was almost completely inhibited by the TXA2 receptor antagonists. 4. In single cells of isolated crypts, STA2 depolarized the cell and increased the membrane conductance, indicating that STA2 opened the apical Cl- channel of the crypt cells. 5. We conclude, therefore, that the irinotecan-induced endogenous TXA2 is a novel stimulant of the Cl- secretion from the crypt cells of distal colon.

Animals↗

PubMed1997

An Aspergillus awamori acetylesterase: purification of the enzyme, and cloning and sequencing of the gene.

An inducible acetylesterase was purified from the culture medium of Aspergillus awamori strain IFO4033 growing on wheat-bran culture by ion-exchange, gel-filtration and hydrophobic-interaction chromatographies. The purified enzyme had an Mr of 31000 and contained Asn-linked oligosaccharides. The enzyme liberated acetic acid from wheat bran, hydrolysed only alpha-naphthyl acetate and propionate when aromatic esters were used for the substrate, and was tentatively classified as a carboxylic esterase (EC 3.1.1.1). The gene encoding acetylesterase was cloned and sequenced. The deduced amino acid sequence showed that acetylesterase was produced as a 304-amino-acid-residue precursor, which was converted post-translationally into a 275-amino-acid-residue mature protein. Part of the sequence of acetylesterase was similar to the region near the active-site serine of lipases of Geotrichum candidum and Candida cylindracea. A unique site of putative Asn-linked oligosaccharides was presented.

Amino Acid Sequence↗

PubMed1997

4-alpha-glucanotransferase from the hyperthermophilic archaeon Thermococcus litoralis--enzyme purification and characterization, and gene cloning, sequencing and expression in Escherichia coli.

4-Alpha-Glucanotransferase was purified from cells of Thermococcus litoralis, a hyperthermophilic archaeon. The molecular mass of the enzyme was estimated to be approximately 87 kDa by gel filtration. The optimal temperature for its activity was 90 degrees C. The enzyme catalyzed the transglycosylation of maltooligosaccharides, yielding maltooligosaccharides of various lengths and glucose. When maltoheptaose was used as the substrate, glucoamylase-resistant and glucoamylase-sensitive saccharides were produced. On incubation of amylose with the T. litoralis enzyme, glucoamylase-resistant but alpha-amylase-sensitive molecules were produced, but the amount of reducing sugar showed only slight increases. These results indicate that the T. litoralis enzyme catalyzes not only intermolecular transglycosylation to produce linear alpha-1,4-glucan, but also intramolecular transglycosylation to produce cyclic alpha-1,4-glucan (cycloamylose), similarly to potato 4-alpha-glucanotransferase (called disproportionating enzyme). The gene encoding the T. litoralis 4-alpha-glucanotransferase was cloned, sequenced and expressed in Escherichia coli. The nucleotide sequence of the gene encoded a 659-amino acid protein with a calculated molecular mass of 77,883 Da. The amino acid sequence of the T. litoralis enzyme showed high similarity with those of alpha-amylases of Pyrococcus furiosus, a hyperthermophilic archaeon, and Dictyoglomus thermophilum, an extremely thermophilic bacterium, but little similarity with those of other known 4-alpha-glucanotransferases.

Amino Acid Sequence↗

PubMed1997

The significant role of telomerase activity in human brain tumors.

BACKGROUND: In this study, telomerase activity in human brain tumors was analyzed. METHODS: Telomerase activity was examined in 41 brain tumor cases (20 of glioblastoma multiformes [GBMs] [14 primary tumors and 6 recurrent tumors], 3 anaplastic astrocytomas [AAs], 4 low grade astrocytomas [LGAs] [World Health Organization Grade 2], 2 oligodendrogliomas [OGs], 9 meningiomas [MNs], and 3 metastatic brain tumors [MBTs]) by means of telomeric repeat amplification protocol assay. The activity of telomerase was compared with histologic diagnosis, the MIB-1 proliferative cell index (PCI), and the patient's prognosis. RESULTS: Twelve of 20 GBMs, 2 of 2 OGs, and 3 of 3 MBTs demonstrated telomerase activity. AAs, LGAs, and MNs exhibited no activity. No clear correlations were confirmed in GBMs between telomerase activity and the MIB-1 PCI data. However, the telomerase activity tended to correlate with the patient's prognosis. CONCLUSIONS: These results suggest that telomerase activity may be an important marker of brain tumor malignancy. Furthermore, the change from negative activity to positive activity in the recurrent tumors appeared to be a useful prognosticator for malignant astrocytic tumor.

Antigens, Nuclear↗

PubMed1997

32P-postlabelling of aromatic DNA adducts in white blood cells and alveolar macrophages of smokers: saturation at high exposures.

DNA adducts may serve as a molecular dosimeter of exposure to cigarette smoke-associated carcinogens such as polycyclic aromatic hydrocarbons (PAH). Target tissues for cigarette smoke-induced carcinogenesis are rarely accessible; therefore, peripheral blood cells or cells obtained by bronchoalveolar lavage (BAL) may be used as surrogate sources of exposed DNA. However, the relationship between cigarette smoke exposure and aromatic-DNA adducts in white blood cells and BAL cells is still unclear. In this study, we examined DNA adduct formation in lymphocytes and BAL cells in several populations of smoking individuals by means of 32P-postlabelling. Significant correlations between the amount of cigarettes smoked per day and the level of aromatic-DNA adducts were found in lymphocytes. In BAL cells, DNA adduct levels were associated with age (p = 0.05) and gender (p = 0.10) after adjustment for smoking behaviour. Adduct formation levelled off at higher exposure levels, suggesting less efficient adduct formation; decreases in the formation of adducts per unit of exposure were found in lymphocytes (r(s) = -0.80, p < 0.001) and BAL cells (r(s) = -0.72, p < 0.001). To assess intra-individual variation in adduct levels at constant smoking behaviour, sampling was repeated after a period of 2 and 6 months. In lymphocytes, repeated measurements with an interval of 2 months were highly correlated (r = 0.84, p = 0.009, n = 8), whereas repeated measurements with an interval of 6 months showed no correlation (r = 0.30, p = 0.27, n = 16). Repeated measurements in BAL cells showed a significant correlation after 6 months (r = 0.68, p = 0.03, n = 10). Furthermore, in a group of occupationally exposed aluminium workers, adduct levels in total white blood cells were correlated with the average concentrations of PAH in the ambient air of workers who smoked cigarettes, whereas in non-smokers, no such relationship was found. We conclude that cigarette smoking may directly or indirectly influence DNA adduct levels and saturation of DNA adduct formation may occur, leading to non-linear dose-response relationships.

Adult↗

PubMed1997

A Novel Numerical Analysis on Surface Charge Densities of an Amphoteric O/W-Type Microemulsion in the Presence of CaCl2 and/or AlCl3

The effect of pH on the surface charge density of the O/W-type microemulsion formed in solutions of an amphoteric surfactant, (N alpha , N alpha -dimethyl-N epsilon -lauroyllysine, DMLL)/n -octane/1-pentanol/CaCl2 or AlCl3 , has been investigated. A novel equation for the surface charge densities in the presence of a multivalent cation (Ca2+ and/or Al3+ ) has been derived taking account of the number of DMLL molecules bound to a multivalent cation (q ). By applying a numerical analysis of this equation, it is possible to determine the intrinsic binding constants (K ) of the multivalent cation and the monovalent anion to the hydrophilic groups of DMLL and the adsorption density (N ) of DMLL molecules on the oil/water interface. Furthermore, N has been found to show pH dependence. N has a maximum value around the isoelectric region (in particular, pH 5-7) of DMLL molecules in the presence of CaCl2 , whereas N increases with increasing pH in the presence of AlCl3 . The surfactant (DMLL) numbers per O/W-type microemulsion droplet, i.e., the aggregation numbers, are successfully obtained as a function of pH in the presence of CaCl2 and/or AlCl3 .

Journal Article↗

PubMed1997

Differential effect of high extracellular Ca2+ on K+ and Cl- conductances in murine osteoclasts.

Effects of the extracellular Ca2+ concentration ([Ca2+]o) on whole cell membrane currents were examined in mouse osteoclastic cells generated from bone marrow/stromal cell coculture. The major resting conductance in the presence of 1 mm Ca2+ was mediated by a Ba2+-sensitive, inwardly rectifying K+ (IRK) current. A rise in -Ca2+-o (5-40 mM) inhibited the IRK current and activated an 4'4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS)-sensitive, outwardly rectifying Cl- (ORCl) current. The activation of the ORCl current developed slowly and needed higher [Ca2+]o than that required to inhibit the IRK current. The inhibition of the IRK current consisted of two components, initial and subsequent late phases. The initial inhibition was not affected by intracellular application of guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) or guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS). The late inhibition, however, was enhanced by GTPgammaS and attenuated by GDPbetaS, suggesting that GTP-binding proteins mediate this inhibition. The activation of the ORCl current was suppressed by pretreatment with pertussis toxin, but not potentiated by GTPgammaS. An increase in intracellular Ca2+ level neither reduced the IRK current nor activated the ORCl current. Staurosporine, an inhibitor for protein kinase C, did not modulate the [Ca2+]o-induced changes in the IRK and ORCl conductances. These results suggest that high [Ca2+]o had a dual action on the membrane conductance of osteoclasts, an inhibition of an IRK conductance and an activation of an ORCl conductance. The two conductances modulated by [Ca2+]o may be involved in different phases of bone resorption because they differed in Ca2+ sensitivity, temporal patterns of changes and regulatory mechanisms.

Animals↗