Evaluation of cutoff scores for the Parkinson's disease sleep scale-2

BACKGROUND

The Parkinson's Disease Sleep Scale (PDSS)-2 is a recently developed tool for evaluating disease-related nocturnal disturbances in patients with Parkinson's disease (PD). However, its cutoff score has not been clinically assessed. We determined the optimal cutoff score of the Japanese version of the PDSS-2.

METHODS

Patients with PD (n = 146) and controls (n = 100) completed the PDSS-2 and the Pittsburgh Sleep Quality Index (PSQI). Poor sleepers were defined as having global PSQI scores >5. Optimal cutoff scores for determining poor sleepers were assessed using the receiver operating characteristic curve.

RESULTS

A PDSS-2 total score ≥ 14 exhibited 82.0% sensitivity and 70.6% specificity, whereas a PDSS-2 total score ≥ 15 provided 72.1% sensitivity and 72.9% specificity in distinguishing poor sleepers (PSQI score >5) from good sleepers (PSQI ≤ 5). Nocturnal disturbances were more frequently observed in patients with PD than in controls (PDSS-2 total score ≥ 14 or ≥ 15; 51.4% vs 20%; 45.9% vs 19%). Nocturnal disturbances were associated with higher Hoehn and Yahr stages and Unified Parkinson's Disease Rating Scale motor scores, impaired quality of life, daytime sleepiness, and depressive symptoms.

CONCLUSION

We suggest that PDSS-2 total scores ≥ 15 are useful for detecting poor sleepers among patients with PD.

White blood cell count is associated with plasma total homocysteine in Japanese men

White blood cell (WBC) count has been related to risk for coronary heart disease. The relationship may be due to the association between WBC count and cardiovascular risk factors. So far, it has been shown that WBC count is associated with body mass index, total cholesterol, triglyceride, glucose, blood pressure and some lifestyle factors. It is not known, however, whether WBC count is associated with other risk factors such as total homocysteine or gamma-glutamyl transferase. The association between WBC count, total homocysteine and gamma-glutamyl transferase was analyzed cross-sectionally in middle-aged Japanese men. In a univariate regression analysis WBC count was associated positively with total homocysteine (beta (standard regression coefficient) = 0.112; p<0.001) but not with gamma-glutamyl transferase (beta = 0.033; p = 0.309). In a multivariate analysis which included cigarette smoking, physical activity, ethanol consumption, vegetable intake and body mass index, the association between WBC count and total homocysteine remained significant (beta = 0.062; p = 0.026). The association may partially explain the reported association between elevated WBC count and cardiovascular disease.

Vital capacity and selected metabolic diseases in middle-aged Japanese men

OBJECTIVE

To elucidate the association between vital capacity and the presence of selected metabolic diseases in middle-aged Japanese men.

METHODS

A cross-sectional analysis of the associations among forced vital capacity (FVC), static vital capacity as a percentage of that predicted (%VC) and the presence of metabolic diseases was performed.

RESULTS

In a univariate linear regression analysis, FVC and %VC were inversely associated with poor vegetable intake, cigarette smoking and body mass index, but not with physical activity or ethanol consumption. In a logistic regression analysis adjusted for lifestyle factors, body mass index and age, the odds ratios for the presence of metabolic disease per 0.54 L (1 SD) decrease in FVC were 1.24 (95% CI 1.03 to 1.50) for type II diabetes, 1.21 (95% CI 1.02 to 1.42) for hypertension, 1.34 (95% CI 1.11 to 1.63) for hypertriglyceridemia, 1.23 (95% CI 1.03 to 1.46) for high gamma-glutamyl transferase levels and 1.63 (95% CI 1.10 to 2.41) for an episode of cardiovascular disease. FVC did not correlate with hyperhomocysteinemia, hypercholesterolemia or high white blood cell count. Similar results were also obtained for the association between %VC and metabolic diseases.

CONCLUSIONS

A decrease in FVC or %VC was associated with the presence of some metabolic diseases. The association may partly explain the reported association between low FVC and cardiovascular disease.

Heavy alcohol intake, homocysteine and Type 2 diabetes

Although moderate alcohol intake is associated with reduced risk of atherosclerotic disease in both the general population and in diabetic patients, a recent report suggests that heavy alcohol intake facilitates the development of atherosclerosis exclusively in diabetic individuals. We studied cross-sectionally the effects of the interaction between ethanol consumption category and the prevalence of diabetes on plasma total homocysteine (tHcy), a risk factor for atherosclerotic disease, in middle-aged men. Heavy drinking was associated with elevated tHcy levels only in diabetic subjects but not in non-diabetic subjects. Plasma tHcy of heavy drinkers (average ethanol consumption > 30 ml/day) was higher than that of abstainers in the diabetic subgroup (10.25 +/- 3.39 vs. 8.88 +/- 1.94 micromol/l, P < 0.05), whereas tHcy levels in heavy drinkers were comparable with that of abstainers in the non-diabetic subgroup (9.36 +/- 2.52 vs. 9.12 +/- 2.10 micromol/l, NS). In a two-factor anova, significant interaction was observed on the effects of ethanol consumption category and diabetes prevalence on tHcy levels (P < 0.01). Confounding factors including folate, vitamin B(12), creatinine, age or cigarette smoking did not contribute to the interaction. These findings may partly explain the reported association between heavy drinking and atherosclerosis in diabetic subjects.

Mode of inheritance of HLA-DRB1 shared epitope in Japanese familial rheumatoid arthritis

OBJECTIVE

To clarify the mode of genetic contribution of the HLA-DR shared epitope (SE) to the pathogenesis of familial cases of Japanese rheumatoid arthritis (RA).

METHODS

Fifty-three unrelated Japanese RA families that had more than 2 affected sibs were selected. The HLA-DR shared epitope typing was carried out by the PCR method and PCR-SSCP (single stranded DNA conformation polymorphism) method. Affected sib pair analysis was carried out using the MAPMAKER/SIB 2.0 program. The mode of inheritance was also calculated based on the sharing of genes identical by descent (IBD) between siblings in each of the 53 affected sib-pairs (propositus and the 2nd affected sib).

RESULTS

The maximum LOD score of HLA-DR was 0.437, and the sharing of 2 IBDs, 1 IBD, and no IBDs between affected sibs were 0.330, 0.500, and 0.170, respectively. The sharing distribution of IBD was confirmed to be compatible with the dominant or additive mode since the observed gene frequency of SE was 0.255.

CONCLUSION

The HLA-DR shared epitope participated in the pathogenesis of familial cases of Japanese RA. The SE contributes to this pathogenesis in either the dominant or additive mode of inheritance.

A case of agranulocytosis associated with severe acute hepatitis B

A 29-year-old male patient with acute hepatitis B developed agranulocytosis about 2 months after the clinical onset of the hepatitis. Bone marrow examination showed hypercellularity and maturation arrest of myeloid leukogenesis at the stage of metamyelocyte. Anti-neutrophil antibody was negative. Since the patient did not show spontaneous recovery for 2 months, the patient received granulocyte-colony stimulating factor, but the therapy was a very short course because he had an elevation of temperature and nausea. Sixty-eight days after admission, he was started on lithium carbonate at a dose of 600 mg per day. About 3 weeks later, peripheral granulocyte counts had recovered to normal level.

Ventroptin: a BMP-4 antagonist expressed in a double-gradient pattern in the retina

In the visual system, the establishment of the anteroposterior and dorsoventral axes in the retina and tectum during development is important for topographic retinotectal projection. We identified chick Ventroptin, an antagonist of bone morphogenetic protein 4 (BMP-4), which is mainly expressed in the ventral retina, not only with a ventral high-dorsal low gradient but also with a nasal high-temporal low gradient at later stages. Misexpression of Ventroptin altered expression patterns of several topographic genes in the retina and projection of the retinal axons to the tectum along both axes. Thus, the topographic retinotectal projection appears to be specified by the double-gradient molecule Ventroptin along the two axes.

Identification of RALDH-3, a novel retinaldehyde dehydrogenase, expressed in the ventral region of the retina

In the developing retina, a retinoic acid (RA) gradient along the dorso-ventral axis is believed to be a prerequisite for the establishment of dorso-ventral asymmetry. This RA gradient is thought to result from the asymmetrical distribution of RA-generating aldehyde dehydrogenases along the dorso-ventral axis. Here, we identified a novel aldehyde dehydrogenase specifically expressed in the chick ventral retina, using restriction landmark cDNA scanning (RLCS). Since this molecule showed enzymatic activity to produce RA from retinaldehyde, we designated it retinaldehyde dehydrogenase 3 (RALDH-3). Structural similarity suggested that RALDH-3 is the orthologue of human aldehyde dehydrogenase 6. We also isolated RALDH-1 which is expressed in the chick dorsal retina and implicated in RA formation. Raldh-3 was preferentially expressed first in the surface ectoderm overlying the ventral portion of the prospective eye region and then in the ventral retina, earlier than Raldh-1 in chick and mouse embryos. High level expression of Raldh-3 was also observed in the nasal region. In addition, we found that Pax6 mutants are devoid of Raldh-3 expression. These results suggested that Raldh-3 is the key enzyme in the formation of an RA gradient along the dorso-ventral axis during the early eye development, and also in the development of the olfactory system.

Inwardly rectifying K+ channel Kir7.1 is highly expressed in thyroid follicular cells, intestinal epithelial cells and choroid plexus epithelial cells: implication for a functional coupling with Na+,K+-ATPase

A novel inwardly rectifying K+ channel, Kir7.1, with unique pore properties, was cloned recently. Working in the field of osmoregulation, we have also identified the same human and rat channel and found that the channel is unique not only in its pore sequence but also in its dense localization in the follicular cells of the thyroid gland. Northern blot analysis revealed that the channel message was abundantly expressed in the thyroid gland and small intestine, and moderately in the kidney, stomach, spinal cord and brain. Immunohistochemistry of the rat thyroid, intestine and choroid plexus demonstrated the expression of the channel protein in the follicular cells and epithelial cells, suggesting a role in the regulation of the ion-transporting functions of these specialized cells. The unique pore properties of Kir7.1 make it a strong candidate for the hypothetical low-conductance K+ channel that is functionally coupled with Na+,K(+)-ATPase by recycling K+. We therefore further examined the co-localization of Kir7.1 and Na+,K(+)-ATPase and found that both are localized in the basolateral membrane of the thyroid follicular cell; in the choroid plexus, which is known to be unique in having Na+,K(+)-ATPase in the apical side of the epithelial cells, Kir7.1 was found in the apical membrane, implying a close functional coupling between the channel and Na+,K(+)-ATPase.

Identification by differential display of a hypertonicity-inducible inward rectifier potassium channel highly expressed in chloride cells

By using differential mRNA display to monitor the molecular alterations associated with adaptation of euryhaline eels to different salinities, we identified a cDNA fragment strongly induced in seawater eel gills. Cloning of a full-length cDNA and its expression in COS-7 cells indicated that the clone codes for an inward rectifier K+ channel (eKir) of 372 amino acid residues, which has two transmembrane segments and a typical pore-forming region (H5). Only low sequence similarities are present, except the H5 region, compared with other members of the inward rectifier K+ channel family (Kir). Consistent with this divergence in the amino acid sequence, a phylogenetic analysis indicated early divergence and independent evolution of eKir from other members; it is only distantly related to the Kir5.0 subfamily members. RNase protection analysis showed that eKir is highly expressed in the seawater eel gill, kidney, and posterior intestine but very weakly in freshwater eels. Immunohistochemistry of gill sections revealed dense localization of eKir in the chloride cells. Immunoelectron microscopy indicated that eKir is mainly present in the microtubular system in the chloride cell. This location and its salt-inducible nature suggest that the eKir channel cloned here is a novel member of the Kir5.0 subfamily of the Kir family and is implicated in osmoregulation.

Successful treatment of bilateral deep femoral aneurysms and multiple iliac aneurysms associated with severe aortic valve disease: report of a case

We report herein the case of a patient in whom aneurysms of the bilateral deep femoral arteries (DFA) and multiple iliac aneurysms associated with severe aortic valve disease were successfully treated by a two-staged operation. The patient was a 74-year-old man who had dense calcification of the ascending aorta and aortic arch. Prior to aortic valve replacement (AVR), the aneurysms of the DFA and internal iliac arteries were resected. The terminal end of the abdominal aorta and bilateral common iliac arteries were then reconstructed with a Y graft to be used as a possible alternative arterial input route in place of the ascending aorta for extracorporeal circulation during the AVR. The inferior mesenteric artery (IMA) was well developed, and the external iliac arteries and their branches were preserved at aneurysmectomy. Postoperatively, there was no ischemia of the pelvic organs or the hip muscles. The AVR was subsequently performed 5 weeks after the first operation, and the patient was discharged after an uneventful postoperative course.

High levels of a major histocompatibility complex II-self peptide complex on dendritic cells from the T cell areas of lymph nodes

T lymphocytes recirculate continually through the T cell areas of peripheral lymph nodes. During each passage, the T cells survey the surface of large dendritic cells (DCs), also known as interdigitating cells. However, these DCs have been difficult to release from the lymph node. By emphasizing the use of calcium-free media, as shown by Vremec et al. (Vremec, D., M. Zorbas, R. Scollay, D.J. Saunders, C.F. Ardavin, L. Wu, and K. Shortman. 1992. J. Exp. Med. 176:47-58.), we have been able to release and enrich DCs from the T cell areas. The DCs express the CD11c leukocyte integrin, the DEC-205 multilectin receptor for antigen presentation, the intracellular granule antigens which are recognized by monoclonal antibodies M342, 2A1, and MIDC-8, very high levels of MHC I and MHC II, and abundant accessory molecules such as CD40, CD54, and CD86. When examined with the Y-Ae monoclonal which recognizes complexes formed between I-Ab and a peptide derived from I-Ealpha, the T cell area DCs expressed the highest levels. The enriched DCs also stimulated a T-T hybridoma specific for this MHC II-peptide complex, and the hybridoma underwent apoptosis. Therefore DCs within the T cell areas can be isolated. Because they present very high levels of self peptides, these DCs should be considered in the regulation of self reactivity in the periphery.

Calcitonin gene-related peptide enhances apoptosis of thymocytes

The effect of calcitonin gene-related peptide (CGRP), a neuropeptide, on the apoptosis of murine thymocytes was investigated. CGRP enhanced apoptosis of thymocytes beyond the spontaneous level at concentrations of 10(-11) M or higher, and the effect attained a plateau at 10(-9) M, mainly by stimulating cAMP formation. Implication of cAMP-independent mechanism was also suggested in the CGRP-induced apoptosis. Flow cytometric analysis revealed that CGRP caused apoptosis preferentially in CD4+8+ thymocytes. In addition, RNA and protein synthesis was required for apoptosis induced by CGRP.

Exogenous and endogenous type I interferons inhibit interferon-gamma-induced nitric oxide production and nitric oxide synthase expression in murine peritoneal macrophages

We investigated the effect of type I IFNs (IFN-alpha and IFN-beta) on IFN-gamma-induced nitric oxide (NO) production by murine peritoneal macrophages. It was found that exogenous and also endogenous type I IFNs suppressed IFN-gamma-induced NO production, cytosolic inducible NO synthase (iNOS) activity, and iNOS mRNA accumulation in macrophages. Furthermore, we show here that type I IFNs prevent the NO-mediated deterioration of mitochondrial respiratory activity in macrophages. These results seem to indicate a possible protective role of type I IFNs against the NO-mediated immunosuppressive and/or cytotoxic effect of macrophages.

Calcitonin gene-related peptide enhances cytokine-induced IL-6 production by fibroblasts

The effect of calcitonin gene-related peptide (CGRP) was investigated on cytokine-induced IL-9 production by Swiss 3T3 fibroblasts. CGRP by itself had little effect on IL-6 production, and substantially enhanced that induced by IL-1 beta or TNF alpha at concentrations of 10(-8) M or higher. The action of CGRP was mediated by a CGRP-specific receptor. In contrast, calcitonin had no effect at all. A kinetic study of IL-6 activity in the culture supernatant showed that CGRP not only accelerated but also increased IL-6 production. Enhancement by CGRP of cytokine-dependent IL-6 production was ascribed to the increased accumulation of IL-6 mRNA. IL-1 beta-induced IL-6 production was maintained by CGRP after removal of IL1 beta. The addition of CGRP to the culture following stimulation with IL-1 beta or IL-1 beta plus CGRP decelerated the decay of IL-6 mRNA. These results indicate that the augmenting effect of CGRP is mediated, at least in part, by the stabilization of IL-6-specific mRNA.

Enhancement of murine bone marrow macrophage differentiation by beta-endorphin

The present study was performed to investigate the effect of beta-endorphin on macrophage colony-stimulating factor (M-CSF)-induced differentiation of macrophages from bone marrow cells in a semisolid culture system. beta-endorphin increased the number of macrophage colonies when bone marrow cells were cultured in the presence of M-CSF plus lipopolysaccharide (LPS). This was not the case with LPS-unresponsive C3H/HeJ mouse bone marrow cells. alpha-endorphin and gamma-endorphin were as effective as beta-endorphin in enhancing the colony formation. Exogenous interleukin-1 (IL-1), but neither IL-6 nor tumor necrosis factor (TNF), collaborated with beta-endorphin even in the absence of LPS, suggesting that IL-1 is a primary mediator of the effect of LPS. Indeed, anti-IL-1 antibody abolished the collaborative effect of beta-endorphin with LPS. Moreover, IL-1 was effective even for C3H/HeJ mouse bone marrow cells. Naloxone, an antagonist of endorphins for opioid-receptors, completely abrogated the effect of beta-endorphin. In a single-cell culture system, the collaboration between beta-endorphin and IL-1 was revealed by the increase in number and size of macrophage colonies, but collaboration between beta-endorphin and LPS did not occur. These results indicate that, in mixed cell culture, beta-endorphin acts in concert with paracrinal IL-1 induced by LPS to enhance M-CSF-dependent macrophage differentiation from immature precursor cells.

[ATP-sensitive potassium channel and hormone/neuropeptide]

ATP-sensitive potassium channels (KATP) are the ion channels which are closely associated with cellular metabolism. A number of chemical compounds which block KATP facilitate the release of hormones or neuropeptides. For example, KATP-blocking agents such as antidiabetic sulfonylureas and imidazolines stimulate insulin secretion from pancreatic beta-cells by decreasing KATP activity. On the other hand, so-called potassium channel openers, KATP-activating drugs which constitute a chemically diverse group of compounds, inhibit growth hormone secretion from anterior pituitary cells and release of gamma-aminobutylic acid from substantia nigra. Several endogenous substances also modulate release of hormone or neuropeptide by affecting KATP activity. Acetylcholine and histamine stimulate the release of endothelium-derived hyperpolarizing factor, which activates KATP in the plasma membrane of vascular smooth muscle cells. Both galanin and somatostatin inhibit insulin release from pancreatic beta-cells by opening KATP through the activation of G-protein. Glucagon-like peptide-1[7-36], which stimulates insulin secretion by indirectly blocking KATP in beta-cells, shows antidiabetic effects in patients with non-insulin-dependent diabetes mellitus. Endosulphine, an endogenous inhibitor of KATP, stimulates insulin secretion from pancreatic beta-cells. Accumulating knowledge of the modulation and function of KATP would help our understanding of the regulation and physiological role of hormones and neuropeptides.

[Pharmacology of glibenclamide-sensitive K+ channels in follicle-enclosed Xenopus oocytes]

Follicle-enclosed Xenopus oocytes have endogenous glibenclamide-sensitive K+ channels that can be activated by K+ channel openers. Since the follicle-enclosed Xenopus oocytes can be easily voltage-clamped, the K+ channels are used as a model of the ATP/glibenclamide-sensitive K+ channels. So far, the effects of calmodulin antagonists, antiarrhythmics, anesthetics, antidepressants, histamine H1-receptor antagonists, imidazolines and several hormones on the K+ channels of the oocytes have been reported. The pharmacological data on the K+ channels obtained from the oocyte-system may contribute to our understanding of the regulatory mechanism and physiological role of the ATP/glibenclamide-sensitive K+ channels.

Inhibition by antidepressants of glibenclamide-sensitive K+ currents in follicle-enclosed Xenopus oocytes

Effects of antidepressive drugs on glibenclamide-sensitive K+ currents were investigated using follicle-enclosed Xenopus oocytes. Antidepressive drugs, imipramine, desipramine, and amitriptyline, inhibited the K+ currents with IC50 (microM) values of 35.4, 39.7, and 87.7, respectively. The K+ current blocking actions of antidepressants appear to be associated with their local anesthetic related structures.

The tissue distribution of the B7-2 costimulator in mice: abundant expression on dendritic cells in situ and during maturation in vitro

B7-2 is a recently discovered, second ligand for the CTLA-4/CD28, T cell signaling system. Using the GL-1 rat monoclonal antibody (mAb), we monitored expression of B7-2 on mouse leukocytes with an emphasis on dendritic cells. By cytofluorography, little or no B7-2 was detected on most cell types isolated from spleen, thymus, peritoneal cavity, skin, marrow, and blood. However, expression of B7-2 could be upregulated in culture. In the case of epidermal and spleen dendritic cells, which become highly immunostimulatory for T cells during a short period of culture, the upregulation of B7-2 was dramatic and did not require added stimuli. Lipopolysaccharide did not upregulate B7-2 levels on dendritic cells, in contrast to macrophages and B cells. By indirect immunolabeling, the level of staining with GL-1 mAb exceeded that seen with rat mAbs to several other surface molecules including intercellular adhesion molecule 1, B7-1, CD44, and CD45, as well as new hamster mAbs to CD40, CD48, and B7-1/CD80. Of these accessory molecules, B7-2 was a major species that increased in culture, implying a key role for B7-2 in the functional maturation of dendritic cells. B7-2 was the main (> 90%) CTLA-4 ligand on mouse dendritic cells. When we applied GL-1 to tissue sections of a dozen different organs, clear-cut staining with B7-2 antigen was found in many. B7-2 staining was noted on liver Kupffer cells, interstitial cells of heart and lung, and profiles in the submucosa of the esophagus. B7-2 staining was minimal in the kidney and in the nonlymphoid regions of the gut, and was not observed at all in the brain. In the tongue, only rare dendritic cells in the oral epithelium were B7-2+, but reactive cells were scattered about the interstitial spaces of the muscle. In all lymphoid tissues, Gl-1 strongly stained certain distinct regions that are occupied by dendritic cells and by macrophages. For dendritic cells, these include the thymic medulla, splenic periarterial sheaths, and lymph node deep cortex; for macrophages, the B7-2-rich regions included the splenic marginal zone and lymph node subcapsular cortex. Splenic B7-2+ cells were accessible to labeling with GL-1 mAb given intravenously. Dendritic cell stimulation of T cells (DNA synthesis) during the mixed leukocyte reaction was significantly (35-65%) blocked by GL-1.(ABSTRACT TRUNCATED AT 400 WORDS)

Vanadate-induced oscillatory inward Cl- currents in Xenopus laevis oocytes

Extracellularly applied sodium orthovanadate (30-3000 microM) evoked oscillatory inward Cl- currents in defolliculated Xenopus laevis oocytes. The current responses were attenuated by microinjection of EGTA into the oocytes and by treatment of the oocytes with pertussis toxin (2 micrograms/ml). The vanadate responses were not affected by preceding vanadate (1 mM) responses or an angiotensin II (200 nM) response, or by pre-application of atropine (5 microM). Intracellular injection of vanadate was ineffective. These results suggest that vanadate stimulates Ca2+ mobilization in Xenopus oocytes possibly by activating surface membrane receptors, which is coupled to pertussis toxin-sensitive G-protein.

Potentiation by insulin and insulin-like growth factor-1 of glibenclamide-sensitive K+ currents in follicle-enclosed Xenopus oocytes

Effects of insulin and IGF-1 (insulin-like growth factor-1) on K+ channel opener-induced/glibenclamide-sensitive K+ currents were studied using follicle-enclosed Xenopus oocytes. Both insulin (4 x 10(-9)-4 x 10(-6) M) and IGF-1 (4 x 10(-10)-4 x 10(-7) M) increased the cromakalim-induced K+ currents in a concentration-dependent manner. The current-facilitating effect of IGF-1 was about ten times as potent as that of insulin. Treatment of the oocyte with pertussis toxin (2 micrograms/ml) suppressed the current-potentiating effects of insulin and IGF-1 by about 60%. Although phenylarsine oxide (1-100 microM), a putative inhibitor of protein tyrosine phosphatase, also facilitated the K+ currents, the current enhancing effects were not affected by pertussis toxin. These results suggest that insulin and IGF-1 potentiate the glibenclamide-sensitive K+ current by activating IGF-1 receptor and that pertussis toxin-sensitive G-protein may be associated with these effects.

Inhibition by imidazoline and imidazolidine derivatives of glibenclamide-sensitive K+ currents in Xenopus oocytes

The effects of imidazoline and imidazolidine derivatives on glibenclamide-sensitive K+ currents induced by the novel K+ channel opener, Y-26763 ((+)-(3S,4R)-4-(N-acetyl-N-benzyloxyamino)-6-cyano-3,4-dihydro-2,2 -dimethyl-2H-1-benzopyran-3-ol), were investigated in voltage-clamped follicle-enclosed Xenopus oocytes. Of 14 imidazoline derivatives and seven imidazolidine derivatives tested, phenotalmine, (-)-cibenzoline, (+)-cibenzoline, alinidine, oxymetazoline, antazoline, midaglizole, xylometazoline, tramazoline and ST91 (2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride) potently suppressed Y-26763-induced K+ currents (IC50 < 80 microM). The compounds which lack an aromatic ring in their structure, 2-methyl-2-imidazole and 2-hydrazino-2-imidazoline, did not affect the K+ currents. Clonidine and idazoxan, which both bind to imidazoline-preferring binding sites with high affinity in various tissues, showed only a small inhibitory effect on Y-26763-induced K+ currents (IC50 780 microM and 955 microM, respectively). The non-imidazoline/non-imidazolidine alpha-adrenoceptor antagonists, WB-4101 (2-(2,6-dimethoxy-phenoxyethyl)-aminomethyl-1,4-benzodioxane hydrochloride), yohimbine and rauwolscine, showed suppressive effects on Y-26763-induced K+ currents (IC50 203 microM, 813 microM and 832 microM, respectively). Octopamine (1 mM), a non-imidazoline/non-imidazolidine alpha-adrenoceptor agonist, was inactive. The results suggest that (1) an aromatic ring or aromatic rings are an essential moiety for imidazoline or imidazolidine derivatives to block glibenclamide-sensitive K+ currents in oocytes, and (2) the K+ current-blocking ability of imidazolines and imidazolidines is related to the alkylation of the benzene ring and the existence of a tertiary amine structure. The K+ current-blocking effects of imidazolines or imidazolidines may not be mediated by alpha-adrenoceptors, at least in follicle-enclosed Xenopus oocytes.

Atrial natriuretic factor potentiates glibenclamide-sensitive K+ currents via the activation of receptor guanylate cyclase in follicle-enclosed Xenopus oocytes

The effect of the atrial natriuretic factor (ANF) on K+ channel opener-induced glibenclamide-sensitive K+ currents was studied using follicle-enclosed Xenopus oocytes. K+ currents induced by the K+ channel opener Y-26763 were potentiated by ANF (0.5-50 nM) in a concentration-dependent manner. 50 nM ANF increased the peak amplitude of the current by 59.4 +/- 9.9% (mean +/- S.E., n = 8). ANF (1-1000 nM) increased the cGMP contents of follicle-enclosed oocytes; about 13-fold increase was achieved by 100 nM ANF, showing a peak at 5 min. The ANF-stimulated accumulation of cGMP was suppressed by HS-142-1 (a non-peptide antagonist of the ANF receptor), at concentrations of 3-300 micrograms/ml. The K+ current-potentiating effect of ANF was mimicked by membrane-permeable cGMP (1 mM 8-bromo cGMP). These results suggest that ANF potentiates glibenclamide-sensitive K+ currents via the activation of receptor guanylate cyclase and consequent accumulation of cGMP in follicle-enclosed Xenopus oocytes.

Effects of Ca2+ channel antagonists and their isomers on glibenclamide-sensitive K+ currents in follicle-enclosed Xenopus oocytes

Several Ca2+ channel antagonists were shown to inhibit glibenclamide-sensitive K+ currents in follicle-enclosed Xenopus oocytes. We have investigated the stereoselectivity of the effects of Ca2+ channel antagonists on the glibenclamide-sensitive K+ currents induced by Y-26763 (a K+ channel opener) in follicle-enclosed Xenopus oocytes. (-)-Bepridil and (+)-bepridil similarly suppressed Y-26763-induced K+ currents with IC50 values of 7.8 microM and 7.4 microM, respectively. The Ca2+ channel antagonists, (-)- and (+/-)-verapamil, and inactive (+)-verapamil suppressed Y-26763-induced K+ currents to similar extents and their IC50 values were 63.1 microM and 55.0 microM, respectively. The Ca2+ channel antagonist, SD-3211 and its less potent (-)-isomer, SD-3212, suppressed Y-26763-induced K+ currents with similar IC50 values of 10.7 microM and 8.9 microM, respectively. Of all the Ca2+ channel antagonists tested, only diltiazem exhibited stereoselectivity. The rank order of potencies (IC50 in microM) of four isomers of diltiazem to block Y-26763-induced K+ currents was (+)-trans (4.2) > (-)-trans (13.3) > (-)-cis (35.8) > (+)-cis (75.9), which was, however, opposite to that of their potencies as Ca2+ channel antagonists. These results indicate that blockade by Ca2+ channel antagonists of glibenclamide-sensitive K+ currents in follicle-enclosed Xenopus oocytes is not mediated by Ca2+ channel antagonism.

Inhibition by SKF 525A and quinacrine of endogenous glibenclamide-sensitive K+ channels in follicle-enclosed Xenopus oocytes

Effects of local anesthetics-related drugs, SKF 525A (proadifen, a cytochrome P450 inhibitor) and quinacrine (a phospholipase A2 inhibitor) on glibenclamide-sensitive K+ currents were investigated using native Xenopus oocytes. SKF 525A and quinacrine suppressed cromakalim-induced/glibenclamide-sensitive K+ currents with IC50 values of 9.8 microM and 4.4 microM, respectively. Inhibitors of either cytochrome P450 or phospholipase A2, which are structurally unrelated to local anesthetics, however, did not affect the K+ currents. Similar results were obtained for Y-26763-induced/glibenclamide-sensitive K+ currents. SKF 525A and quinacrine block the glibenclamide-sensitive K+ currents by a mechanism irrelevant to the inhibition of cytochrome P450 or phospholipase A2 in oocytes.

Inhibition by histamine H1 receptor antagonists of endogenous glibenclamide-sensitive K+ channels in follicle-enclosed Xenopus oocytes

Effects of histamine receptor ligands on the glibenclamide-sensitive K+ currents induced by K+ channel openers, cromakalim and Y-26763, were examined in follicle-enclosed Xenopus oocytes. Histamine H1 receptor antagonists, promethazine, dimethindene and chlorpheniramine all decreased cromakalim-induced K+ currents with IC50 values of 31.5 microM, 29.5 microM and 138 microM, respectively. These compounds also blocked Y-26763-induced K+ currents with comparable IC50 values. Histamine (1 mM) and histamine H2 receptor antagonists, cimetidine (0.5 mM) and ranitidine (1 mM) had little effect on these K+ currents. These results suggest that histamine H1 receptor antagonists inhibit glibenclamide-sensitive K+ currents by a mechanism other than the histamine H1 receptor antagonism. The inhibitory effects might explain, in part, the reported actions of histamine H1 receptor antagonists in ischemia.

[Unidentified steroid hormone of Cushing's syndrome and disease]

A previously unknown HPLC peak was recently observed in urine samples from patients with Cushing's syndrome and disease. We analysed dansylated derivatives of 17keto steroid glucuronides in urine samples from patients with Cushing's syndrome, Cushing disease and from healthy subjects using high-performance liquid chromatography (HPLC) on reversed-phase Cap Cell PakC8. All urine samples from patients with Cushing's syndrome caused by adrenal adenoma and Cushing's disease showed an unknown large peak at the point between [110HE-G] and [110HA-G] peaks and at a retention time of 25.4 min. The same unknown peak was also observed in urine samples from a patient with asymptomatic cortisol-producing adrenal adenoma and two patients with ectopic ACTH-producing tumor, though the peak height was low for the former and one of the latter but high for the second of the two patients. In contrast, healthy male and female urine only showed a very small peak at the same retention time. Urine samples from a Cushing disease treated with op'DDD and Cushing's syndrome bilaterally adrenalectomized and treating with cortisol showed no such peak. The retention time of this unknown peak is clearly different from that of seven 17keto steroid standard glucuronide conjugates. The structure of this substance may be closely related to [110HE-G] or [110HA-G].

Effects of local anesthetics and related drugs on endogenous glibenclamide-sensitive K+ channels in Xenopus oocytes

Effects of local anesthetics and structurally related drugs on the glibenclamide-sensitive K+ currents evoked by Y-26763 (a K+ channel opener) were investigated in native Xenopus oocytes. The K+ current induced by Y-26763 (100 microM) was reversibly suppressed by all six local anesthetics tested in a concentration-dependent manner with the rank order of potencies (IC50 in microM): bupivacaine (67) > dibucaine (136) > tetracaine (845) > lidocaine (1710) = mepivacaine (1945) > procaine (3112). (+)-Propranolol and mexiletine also suppressed Y-26763-induced K+ currents with IC50 values of 115 microM and 789 microM, respectively. These results suggest that a suppressive action on glibenclamide-sensitive K+ channels is the common property of local anesthetics.

Antiarrhythmic drugs, clofilium and cibenzoline are potent inhibitors of glibenclamide-sensitive K+ currents in Xenopus oocytes

1. The novel K+ channel opener, Y-26763 induced outward K+ currents in voltage-clamped follicle-enclosed Xenopus oocytes in a concentration-dependent manner with an EC50 value of 58 microM. 2. The Y-26763-induced K+ current was completely and reversibly blocked by glibenclamide (an ATP-sensitive K+ channel blocker) in a concentration-dependent manner (IC50 140 nM). Effects of several antiarrhythmic drugs on Y-26763-induced glibenclamide-sensitive K+ currents were investigated. 3. (+/-)-Cibenzoline, RS-2135, pirmenol, lorcainide and KW-3407 (class I antiarrhythmic drugs, Na+ channel blockers) suppressed Y-26763 responses in a concentration-dependent manner with IC50 values (in microM) of 6.6, 54, 68, 71 and 370, respectively. 4. Clofilium, E-4031, MS-551 and bretylium (class III antiarrhythmic drugs which increase the action potential duration) also suppressed Y-26763 responses concentration-dependently, IC50 values (in microM) were 3.3, 660, 980 and > or = 2000, respectively. N-acetylprocainamide (class III antiarrhythmic drug) scarcely suppressed Y-26763 responses. 5. The glibenclamide-sensitive K+ currents elicited by KRN2391 were also suppressed by all these antiarrhythmic drugs. 6. The antiarrhythmic drugs, clofilium and (+/-)-cibenzoline block glibenclamide-sensitive K+ channels in Xenopus oocytes at concentrations comparable to their therapeutic plasma levels.

Modification by cGMP of glibenclamide-sensitive K+ currents in Xenopus oocytes

Effects of sodium nitroprusside, 8-bromo cGMP and methylene blue on the glibenclamide-sensitive K+ current evoked by K+ channel openers in Xenopus oocytes were studied. Sodium nitroprusside (0.1-1 mM, an activator of guanylate cyclase) enhanced by 20-50% the K+ currents induced by KRN2391, nicorandil and cromakalim (K+ channel openers). 8-Bromo cGMP (1 mM) also increased the K+ current by 40-60%. Methylene blue (10 microM, an inhibitor of guanylate cyclase) irreversibly blocked the K+ current by about 20-30%. These results suggest that the activation of glibenclamide-sensitive K+ channels by K+ channel openers is modulated either positively or negatively by intracellular cGMP in oocytes.

Activation by KRN2391 and nicorandil of glibenclamide-sensitive K+ channels in Xenopus oocytes

KRN2391 (N-cyano-N'-(2-nitroxyethyl)-3-pyridine-carboximidamide methanesulfonate) and nicorandil, a new class of K+ channel openers, each with an NO2 moiety, induced outward K+ currents in follicle-enclosed Xenopus oocytes. These K+ currents were suppressed concentration-dependently and reversibly by glibenclamide, phentolamine and trifluoperazine, all known to inhibit ATP-sensitive K+ channels. The nicorandil-induced K+ current was virtually abolished by defolliculation of oocytes, while the KRN2391 response was little affected by defolliculation. These results suggest that Xenopus oocyte has at least two types of glibenclamide-sensitive K+ channels, one is selectively sensitive to KRN2391 and is probably localized in the oocyte, and the other is sensitive to nicorandil and distributed in the follicle cells surrounding an oocyte.

Blockade by antiarrhythmic drugs of glibenclamide-sensitive K+ channels in Xenopus oocytes

1. The outward K+ current induced by KRN2391 (K+ channel opener) in Xenopus oocytes is blocked by glibenclamide. We have investigated the effects of various classes (I-IV) of antiarrhythmic drugs on this KRN2391-induced response. 2. All class I antiarrhythmic drugs (Na+ channel blockers) tested concentration-dependently suppressed KRN2391-induced responses with the rank order of potency (IC50 in microM), disopyramide (17.8) > aprindine (29.5) > propafenone (63.1) > ajmaline (145) > quinidine (151). Flecainide, SUN1165, lignocaine, mexiletine and procainamide were much less potent (IC50, 450- > 1000 microM) than quinidine. 3. The class II antiarrhythmic drugs (beta-blockers), timolol, (-)- and (+/-)- propranolol, and (+)- propranolol (a non-beta-blocker) inhibited KRN2391-induced K+ currents in a concentration-dependent manner with values for IC50 (microM) of 79, 131, 151 and 129, respectively, whilst butoxamine, oxprenolol, alprenolol, pindolol, nadolol, metoprolol and acebutolol were either weak (IC50, 300 microM-600 microM) or virtually inactive (IC50, > 1000 microM). 4. The class III antiarrhythmic drugs, amiodarone and (+)-sotalol scarcely affected KRN2391 responses. 5. All class IV drugs (Ca2+ antagonists) tested suppressed KRN2391-induced responses in a concentration-dependent manner with an IC50 of 6.3 microM for bepridil, 38 microM for prenylamine, 85 microM for verapamil and 135 microM for diltiazem. 6. In conclusion, antiarrhythmic drugs of classes I, II and IV potently blocked glibenclamide-sensitive K+ channels in Xenopus oocytes.

Inactivation of glibenclamide-sensitive K+ channels in Xenopus oocytes by various calmodulin antagonists

In follicle-enclosed Xenopus oocytes, extracellular application of cromakalim (a K+ channel opener) or intracellular injection of cAMP induces the smooth outward K+ current which is inactivated by glibenclamide. We found that cromakalim- or cAMP-induced K+ currents in the oocytes were rapidly, reversibly and dose-dependently blocked by various drugs having a calmodulin antagonizing activity in common, namely, by a selective calmodulin antagonist (W-7), antipsychotics (trifluoperazine, chlorpromazine, haloperidol), an antidepressant (amitriptyline), a beta-adrenoceptor blocker (propranolol), a local anesthetic (lidocaine) and a calcium antagonist (prenylamine). W-7, trifluoperazine, chlorpromazine and prenylamine were relatively potent blockers. For example, IC50 values to block cromakalim (100 microM)-induced K+ currents were 12 microM for trifluoperazine and 16 microM for W-7, which were close to their IC50 values to inhibit Ca2+/calmodulin-dependent phosphodiesterase (an index of the potency of calmodulin antagonists). IC50 values to inhibit cAMP (20 pmol/oocyte)-induced K+ currents were 126 microM for prenylamine and 129 microM for chlorpromazine. The IC50 values of all drugs tested to block cromakalim or cAMP responses were significantly correlated with their calmodulin-antagonizing potencies. Isoproterenol-induced K+ currents in the oocytes were also dose-dependently inhibited by glibenclamide, W-7 and trifluoperazine. These results suggest the possibility that the activity of glibenclamide-sensitive K+ channels in follicle-enclosed oocytes are regulated by calmodulin or a calmodulin-dependent process.

Oscillatory muscarinic acetylcholine responses of Xenopus oocytes are desensitized by protein kinase C and sensitized by protein phosphatase 2B

The oscillatory current response to acetylcholine (ACh) in Xenopus laevis oocytes, mediated by endogenous muscarinic ACh receptors, is known to be mildly desensitized by repetitive ACh applications. Pretreatment of oocytes with staurosporine (an inhibitor of protein kinases) was found not only to abolish this desensitization but also to positively and progressively potentiate oscillatory ACh responses. This sensitization by staurosporine was suppressed by 12-O-tetradecanoylphorbol 13-acetate (an activator of protein kinase C). In staurosporine-untreated (control) oocytes, intracellularly injected calcineurin (an isozyme of Ca2+/calmodulin-dependent protein phosphatase 2B) or Ca2+ enhanced oscillatory ACh responses, while trifluoperazine (a calmodulin inhibitor) suppressed the ACh responses but did not affect oscillatory responses to intracellularly injected inositol 1,4,5-trisphosphate. These results suggest that, as far as short-term changes in receptor responsiveness are concerned, endogenous muscarinic ACh receptors in Xenopus oocytes are desensitized by phosphorylation by protein kinase C and sensitized by dephosphorylation by Ca2+/calmodulin-dependent protein phosphatase 2B.

Desensitization of endogenous angiotensin II receptors in Xenopus oocytes: a role of protein kinase C

The inward chloride current induced by angiotensin II (AII) in Xenopus oocytes shows strong and homologous desensitization, and was suggested to be mediated by phosphatidylinositol (PI) hydrolysis (Sakuta et al., 1991, Eur. J. Pharmacol. Mol. Pharmacol. 208, 31). As a model of agonist-induced desensitization of receptors coupled with PI hydrolysis, the mechanism of the desensitization of endogenous AII receptors in oocytes was investigated. Incubation of collagenase-treated oocytes with staurosporine significantly augmented the peak amplitude of AII responses, prolonged their duration, and increased the ratio of oocytes responsive to AII. Moreover, staurosporine-pretreatment made oocytes be consistently responsive to every application of AII. These effects of staurosporine were inhibited by incubation of staurosporine-treated oocytes with 12-O-tetradecanoylphorbol 13-acetate (TPA) but not with dibutyryl cAMP. TPA also attenuated AII responses in staurosporine-untreated control oocytes. These results suggest that staurosporine suppresses the desensitization of endogenous AII receptors in oocytes by blocking protein kinase C (PKC), and the desensitization is likely to be due to phosphorylation by PKC of the receptors or the molecules comprising an AII receptor complex.

Endogenous angiotensin II receptors in Xenopus oocytes and eggs

Angiotensin II (AII) induced strongly desensitizing oscillatory Cl- inward currents in both follicle-enclosed and collagenase-treated Xenopus oocytes. The AII response was abolished by EGTA and attenuated by pertussis toxin. Treatment of oocytes with collagenase transiently reduced both the ratio of oocytes responsive to AII and the amplitude of AII responses, followed by restoration to original levels in 3-4 days. The response to adrenaline, which is mediated by endogenous beta-adrenoceptors in follicle cells, however, was irreversibly abolished by collagenase treatment. These results suggest that endogenous current-mediating AII receptors in oocytes are coupled with phosphatidylinositol hydrolysis and localized in the oocyte or in a cellular structure distinct from that for endogenous beta-adrenoceptors. Progesterone-matured Xenopus eggs also responded to AII, and this AII-induced depolarization resembled the fertilization potential in the eggs, suggesting a possible role of AII receptors in processes of fertilization or growth of the eggs.

GABAB receptors expressed in Xenopus oocytes by guinea pig cerebral mRNA are functionally coupled with Ca2(+)-dependent Cl- channels and with K+ channels, through GTP-binding proteins

Transmembrane currents induced by (-)-baclofen (BAC), a specific agonist of the gamma-aminobutyric acid-B (GABAB) receptor, in Xenopus oocytes injected with guinea pig cerebral mRNA were electrophysiologically and pharmacologically characterized under a voltage-clamp condition. The oocytes injected with mRNA acquired responsiveness to BAC and showed two types of currents at a holding potential of -50 mV. One was the slow and smooth inward current which had a short latency and associated with a decrease in membrane conductance, and its amplitude was decreased by hyperpolarization and increased by depolarization. The other was the large fast oscillatory inward current with a long-latency, which was decreased in amplitude by depolarization and reversed at -26 mV. Both currents were not blocked by bicuculline but were depressed by 2-hydroxysaclofen (2-OH-SAC), though the smooth current was less sensitive to 2-OH-SAC; about 40% blockade at the 2-OH-SAC concentration capable of abolishing the oscillatory current. The smooth current was depressed by Ba2+. The oscillatory current was time-dependently attenuated and almost abolished by intracellularly injected pertussis toxin (PTX), while the smooth current was not depressed by this toxin even when the oscillatory current was nearly abolished. The intracellular injection of GTP-gamma-S into oocytes attenuated both oscillatory and smooth currents. These results suggest the possibility that GABAB receptors expressed in Xenopus oocytes by cerebral mRNA are functionally coupled with two signal transduction systems, one is the opening of Ca2(+)-dependent Cl- channels mediated by PTX-sensitive GTP-binding protein(s) and the other is the closure of K+ channels through PTX-insensitive GTP-binding protein(s).

Separate measurements of surface shapes and refractive index inhomogeneity of an optical element using tunable-source phase shifting interferometry

A phase shifting interferometer using a tunable laser as a light source is proposed for measuring shapes of both surfaces of a glass plate and the distribution of refractive index. To separate the superimposed interferograms generated with many wavefronts reflected from the plate, the phase shift associated with the wavelength shift is applied in the phase shifting interferometer with unequal optical paths in testing and reference beams. A laser diode is used for the tunable light source, and the data processing for obtaining phase distribution is based on the least-squares fitting in interferograms. The rms errors of the measurements are <1/50 wavelength for the surface shape, and 10(-5) of the refractive index for a 5-mm thick optical glass plate.