Exploring urinary biomarkers in autosomal dominant polycystic kidney disease.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD), the most common inherited kidney disease, is a progressive disease characterized by a bilateral proliferation and enlargement of renal cysts. Recent reports have shown that tolvaptan, a vasopressin V2 receptor antagonist, has been effective in inhibiting renal cyst proliferation and enlargement in ADPKD patients, although no biomarker has identified to predict the effects of tolvaptan. We explored the effective urinary biomarkers in ADPKD in human and in an animal model. METHODS: We measured 28 biomarkers in urine taken from ADPKD patients to compare with that of healthy subjects. Next, a gene expression analysis of the kidney from DBA/2FG-pcy mice (ADPKD model animals) was performed to identify prospective biomarkers. Additionally, we investigated the DBA/2FG-pcy mouse urine samples to determine the biomarkers' efficacy. RESULTS: There were statistically significant differences in 12 of the 28 prospective urinary biomarkers between urine from ADPKD patients and that from healthy subjects. Six of these matched with highly expressed gene products of DBA/sFG-pcy mouse kidneys. Among those 6 biomarkers, NGAL, M-CSF, and MCP-1 showed significantly higher values in the urine of DBA/2FG-pcy mice than that of wild type. CONCLUSIONS: This study suggests that NGAL, M-CSF, MCP-1 are potential candidates of urinary biomarkers in ADPKD.

Daily variance of urinary excretion of AQP2 determined by sandwich ELISA method.

BACKGROUND: Urinary excretion of aquaporin 2 (AQP2) is a useful marker of kidney collecting duct function. A specific and convenient method to measure AQP2 in human urine would help to treat water balance disorders. It is unknown whether urinary excretion of AQP2 shows any daily variance. METHODS: A sandwich enzyme-linked immunosorbent assay (ELISA) method for AQP2 was established using two different kinds of antibodies, and its sensitivity and specificity were examined. Daily variance of urinary excretion of AQP2 and responses to acute water load were examined. RESULTS: The established ELISA specifically detected urine AQP2 with high sensitivity (detected as low as 0.34 pmol/mL). Urinary excretion of AQP2 did not show daily variance between 9 a.m. and 9 p.m. in healthy subjects. CONCLUSIONS: The developed ELISA method using two different antibodies is convenient and highly sensitive, and could be useful in clinical practice. Urinary excretion of AQP2 is relatively constant from morning to night, and spot urine sampling at any time during this time period does not affect the results.

Enhanced glucose tolerance in the Brattleboro rat.

[Arg(8)]-vasopressin (AVP) plays a crucial role in regulating body fluid retention, which is mediated through the vasopressin V(2) receptor in the kidney. In addition, AVP is involved in the regulation of glucose homeostasis via vasopressin V(1A) and vasopressin V(1B) receptors. Our previous studies demonstrated that vasopressin V(1A) receptor-deficient (V(1A)R-/-) and V(1B) receptor-deficient (V(1B)R-/-) mice exhibited hyperglycemia and hypoglycemia with hypoinsulinemia, respectively. These findings indicate that vasopressin V(1A) receptor deficiency results in decreased insulin sensitivity whereas vasopressin V(1B) receptor deficiency results in increased insulin sensitivity. In addition, vasopressin V(1A) and vasopressin V(1B) receptor double-deficient (V(1AB)R-/-) mice exhibited impaired glucose tolerance, suggesting that the effects of vasopressin V(1B) receptor deficiency do not influence the development of hyperglycemia promoted by vasopressin V(1A) receptor deficiency, and that the blockage of both receptors could lead to impaired glucose tolerance. However, the contributions of the entire AVP/vasopressin receptors system to the regulation of blood glucose have not yet been clarified. In this study, to further understand the role of AVP/vasopressin receptors signaling in blood glucose regulation, we assessed the glucose tolerance of AVP-deficient homozygous Brattleboro (di/di) rats using an oral glucose tolerance test (GTT). Plasma glucose and insulin levels were consistently lower in homozygous di/di rats than in heterozygous di/+ rats during the GTT, suggesting that the blockage of all AVP/vasopressin receptors resulting from the AVP deficiency could lead to enhanced glucose tolerance.

Identification of aquaporin-5 and lipid rafts in human resting saliva and their release into cevimeline-stimulated saliva.

BACKGROUND: It is unknown whether AQP5 and lipid rafts are released into human unstimulated (resting) saliva and saliva in response to secretagogues. METHODS: In order to quantitate the salivary concentration of AQP5, we produced a polyclonal antibody for human AQP5 and developed an enzyme-like immunosorbent assay (ELISA). RESULTS: AQP5 and lipid rafts were identified in human resting saliva. The amount of AQP5 in resting saliva showed a diurnal variation with high levels during waking hours, and an age-related decrease in AQP5 was coincident with the volume of resting saliva. Cevimeline, a muscarinic acetylcholine receptor (mAChR) agonist, induced the release of AQP5 with lipid rafts, amylase, mucin, and lysozyme. Changes in saliva AQP5 levels after cevimeline administration occurred simultaneously with changes in saliva flow rates. Confocal microscopy revealed that AQP5 was located in the apical plasma membrane and showed a diffuse pattern in parotid glands under resting conditions. Following cevimeline administration, AQP5 was predominantly associated with the APM and was localized in the lumen. GENERAL SIGNIFICANCE: AQP5 and lipid rafts were released with salivary proteins from human salivary glands by the stimulation of M3 mAChRs, and that changes in saliva AQP5 levels can be used as an indicator of salivary flow rate and also as a useful index of M3 mAChR agonist's action on human salivary glands.

Procaterol potentiates the anti-inflammatory activity of budesonide on eosinophil adhesion to lung fibroblasts.

BACKGROUND: The interaction between leukocytes and various parenchymal cells is the first step of inflammation. Therefore, the adhesion of eosinophils to lung fibroblasts is thought to be a crucial step in the inflammatory process of asthma. Procaterol, a beta(2)-selective full agonist, is currently prescribed for patients with asthma. In addition to its potent bronchodilatory action, the agonist has been reported to have anti-inflammatory actions. In this study, to examine whether procaterol can potentiate the anti-inflammatory action of glucocorticoids, the effect of procaterol on eosinophil adhesion to normal human lung fibroblasts (NHLF) was assessed in the presence and absence of budesonide, one of the most potent glucocorticoids. METHODS: Following pretreatment of NHLF with tumor necrosis factor-alpha (TNF-alpha) in the presence of various concentrations of procaterol and/or budesonide, the eotaxin-stimulated eosinophil adhesion was determined using the peroxidase activity of eosinophils. To investigate the mechanism of the inhibitory action of procaterol, TNF-alpha-induced expression of adhesion molecules, ICAM-1 and VCAM-1, in NHLF was also evaluated. RESULTS: Pretreatment with procaterol inhibited the adhesion of eosinophils to NHLF in a concentration-dependent manner, and shifted the concentration-response curve of budesonide to the left. Both procaterol and budesonide resulted in concentration-dependent inhibition of expression of ICAM-1 and VCAM-1 in NHLF, and an additive inhibitory effect was found when the agents were combined. CONCLUSIONS: Given the results of this study which indicated that procaterol exerted an additive action on the anti-inflammatory effect of budesonide, procaterol and glucocorticoids may provide better control for asthma when used together than when used separately.

Effects of vasopressin V1b receptor deficiency on adrenocorticotropin release from anterior pituitary cells in response to oxytocin stimulation.

Oxytocin (OT) is one of the secretagogues for stress-induced ACTH release. OT-induced ACTH release is reported to be mediated by the vasopressin V1b receptor in the rat pituitary gland, which contains both OT and V1b receptors. We examined OT-induced ACTH release using primary cultures of anterior pituitary cells from wild-type (V1bR+/+) and V1b receptor knockout (V1bR-/-) mice. OT stimulated similar levels of ACTH release from pituitary cells of V1bR+/+ and V1bR-/- mice. OT-induced ACTH release was significantly inhibited by the selective V1b receptor antagonist SSR149415 and the OT receptor antagonist CL-14-26 in V1bR+/+ mice. In addition, cotreatment with SSR149415 at 10(-6) m and CL-14-26 at 10(-6) m inhibited OT-induced ACTH release to the control level inV1bR+/+ mice. In V1bR-/- mice, OT-induced ACTH release was significantly inhibited by CL-14-26 at 10(-8) m and completely inhibited at 10(-7)m. These results indicate that OT induces the ACTH response via OT and V1b receptors inV1bR+/+ mice but via only OT receptors in V1bR-/- mice. The gene expression level of the OT receptor was significantly higher in the anterior pituitary gland of V1bR-/- mice than in that of V1bR+/+ mice, suggesting that the OT receptor is up-regulated to compensate for ACTH release under conditions of V1b receptor deficiency.

The vasopressin V1b receptor critically regulates hypothalamic-pituitary-adrenal axis activity under both stress and resting conditions.

The neurohypophyseal peptide [Arg(8)]-vasopressin (AVP) exerts major physiological actions through three distinct receptor isoforms designated V1a, V1b, and V2. Among these three subtypes, the vasopressin V1b receptor is specifically expressed in pituitary corticotrophs and mediates the stimulatory effect of vasopressin on ACTH release. To investigate the functional roles of V1b receptor subtypes in vivo, gene targeting was used to create a mouse model lacking the V1b receptor gene (V1bR-/-). Under resting conditions, circulating concentrations of ACTH and corticosterone were lower in V1bR-/- mice compared with WT mice (V1bR+/+). The normal increase in circulating ACTH levels in response to exogenous administration of AVP was impaired in V1bR-/- mice, while corticotropin-releasing hormone-stimulated ACTH release in the V1bR-/- mice was not significantly different from that in the V1bR+/+ mice. AVP-induced ACTH release from primary cultured pituitary cells in V1bR-/- mice was also blunted. Furthermore, the increase in ACTH after a forced swim stress was significantly suppressed in V1bR-/- mice. Our results clearly demonstrate that the V1b receptor plays a crucial role in regulating hypothalamic-pituitary-adrenal axis activity. It does this by maintaining ACTH and corticosterone levels, not only under stress but also under basal conditions.

OPC-28326, a selective femoral arterial vasodilator, augments ischemia induced angiogenesis.

OPC-28326, 4-(N-methyl-2-phenylethylamino)-1-(3,5-dimethyl-4-propionyl-aminobenzoyl) piperidine hydrochloride monohydrate, is a newly developed selective peripheral vasodilator and increases blood flow to lower extremities with alpha2-adrenergic antagonist property. Here, we investigated the effect of OPC-28326 on ischemia-induced angiogenesis. OPC-28326 enhanced tube formation by human aortic endothelial cells (HAECs). Moreover, OPC-28326 enhanced the number of microvessels sprouting from aortic rings embedded in collagen gel. OPC-28326 markedly induced phosphorylation of endothelial nitric oxide synthase (eNOS) in HAECs via phosphatidylinositol-3 kinase PI3K/Akt (PI3K/Akt) pathway. Next, the angiogenic effect of OPC-28326 was evaluated in a mouse hindlimb ischemia model. Blood flow recovery to the ischemic leg was significantly enhanced by OPC-28326. Furthermore, anti-CD31 immunostaining revealed that OPC-28326 increased capillary density in the ischemic muscle. However, OPC-28326 failed to promote blood flow recovery in ischemic hindlimb in eNOS-deficient mice. These results suggest that OPC-28326 promotes angiogenesis, which was associated with activation of eNOS via PI3K/Akt pathway. OPC-28326 might be promising to treat patients with ischemic vascular diseases.

Activation of endothelial nitric oxide synthase by cilostazol via a cAMP/protein kinase A- and phosphatidylinositol 3-kinase/Akt-dependent mechanism.

We investigated the effect of cilostazol on nitric oxide (NO) production in human aortic endothelial cells (HAEC). Cilostazol increased NO production in a concentration-dependent manner, and NO production was also increased by other cyclic-AMP (cAMP)-elevating agents (forskolin, cilostamide, and rolipram). Cilostazol increased intracellular cAMP level, and that effect was enhanced in the presence of forskolin. In Western blot analysis, cilostazol increased phosphorylation of endothelial nitric oxide synthase (eNOS) at Ser(1177) and of Akt at Ser(473) and dephosphorylation of eNOS at Thr(495). Cilostazol's regulation of eNOS phosphorylation was reversed by protein kinase A inhibitor peptide (PKAI) and by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor. Moreover, the cilostazol-induced increase in NO production was inhibited by PKAI, LY294002, and N(G)-nitro-l-arginine methyl ester hydrochloride (l-NAME), a NOS inhibitor. In an in vitro model of angiogenesis, cilostazol-enhanced endothelial tube formation, an effect that was completely attenuated by inhibitors of PKA, PI3K, and NOS. These results suggest that cilostazol induces NO production by eNOS activation via a cAMP/PKA- and PI3K/Akt-dependent mechanism and that this effect is involved in capillary-like tube formation in HAEC.

A novel modification of a flow cytometric assay of phosphorylated STAT1 in whole blood lymphocytes for rapid detection of interferon-alpha signal in vivo.

Phosphorylation of signal transducer and activator of transcription factor 1 (STAT1) is a key response in the type I interferon (IFN) signal cascade. We developed a novel flow cytometric assay for phosphotyrosine-STAT1 (p-STAT1) to rapidly monitor in vivo IFN signaling. Mouse blood stimulated with mouse IFN-alpha was hemolyzed with lysis buffer in place of lymphocyte purification, permeabilized with methanol, and stained with an Alexa Fluor 488-conjugated anti-p-STAT1 antibody. The cells were also stained with phycoerythrin (PE)-conjugated anti-CD45 antibody for eliminating debris (CD45-negative) from leukocytes (CD45-positive), and with PE covalently linked to cyanin 5-conjugated anti-Gr-1 antibody for separating lymphocytes (Gr-1-negative) and granulocytes (Gr-1-positive). When whole blood was treated with IFN-alpha, the Alexa Fluor 488 intensity of lymphocytes increased, reaching a peak within 1 h, and this increase was statistically significant at IFN-alpha concentrations of 100 U/mL and higher. When IFN-alpha was administered intravenously to mice, the Alexa Fluor 488 intensity of blood lymphocytes was increased, reaching a peak in 1 h and returning to baseline at 18 h, and this increase was dose-dependent, with statistically significant increases seen at doses of 1,000 U/body and higher. The kinetics and dose-responses of p-STAT1 levels in the spleen, lung, and liver were similar to those in blood lymphocytes. This new flow cytometric assay of p-STAT1 in peripheral blood leukocytes will be useful for examining IFN-alpha signaling and for monitoring tissue response to IFN-alpha in vivo.

Direct positive chronotropic action by angiotensin II in the isolated mouse atrium.

We observed the direct positive chronotropic effect of angiotensin II in mouse atria and characterized its pharmacological property. C57BL/6J mice were anesthetized with pentobarbital and hearts were quickly excised. Atrial preparations including right and left atrium were isolated and suspended in the organ bath filled with Krebs-Henseleit solution gassed with 95% O2 and 5% CO2. Angiotensin II at concentrations of 10(-10) to 10(-6) M caused concentration-dependent increase in heart rate, and the maximal response was about 13% of that by isoproterenol. The effect was blocked by the selective AT1-receptor antagonist, losartan at concentrations of 10(-6) M, but not by the selective beta-blocker, nadolol at concentration of 10(-5) M. Furthermore, angiotensin I also caused concentration-dependent increase in heart rate, and the effect was blocked by angiotensin converting enzyme (ACE) inhibitor, captopril at concentrations of 10(-6) M. These results suggested that angiotensin I is converted to angiotensin II via ACE system in mice atria, and regulate heart rate through AT1-receptor stimulation, not by beta-adrenergic receptor.

Therapeutic effects of tolvaptan, a potent, selective nonpeptide vasopressin V2 receptor antagonist, in rats with acute and chronic severe hyponatremia.

The therapeutic efficacy of tolvaptan (OPC-41061), a potent, selective nonpeptide vasopressin V(2) receptor antagonist, on acute and chronic severe hyponatremia was assessed in rats. Experiments were designed to demonstrate the efficacy of tolvaptan reducing mortality in an acute model, and controlling the extent of serum sodium elevation without causing abnormal animal behavior suggesting neurological symptoms in a chronic model. In the acute model, rats developed rapidly progressive, severe hyponatremia by continuous sc infusion of [deamino-Cys(1), D-Arg(8)]-vasopressin (10 ng/h) and forced water-loading (additional 10% initial body weight per day). By d 6, untreated rats had a 47% mortality rate. However, rats treated with repeated oral administrations of tolvaptan (1, 3, and 10 mg/kg) produced dose-dependent aquaresis (i.e. urine volume increased and urine osmolality decreased) that resulted in a gradual increase in plasma sodium concentration. Consequently, tolvaptan treatment reduced mortality and, at higher doses, resulted in no observed deaths. In the gradual model, rats receiving a continuous sc infusion of [deamino-Cys(1), D-Arg(8)]-vasopressin (1 ng/h) combined with a liquid diet were induced to stable, severe hyponatremia (approximately 110 mEq/liter), which lead to increased organ weight and water content. Rats receiving dose titrations of tolvaptan (0.25, 0.5, 1, 2, 4, and 8 mg/kg) increased plasma sodium to healthy levels without causing abnormal animal behavior suggesting neurological symptoms or death, improved hyponatremia-driven increases in wet weight and water content in the organs. Thus, in animal models, analogous to the hyponatremia forms seen in humans, tolvaptan presents exciting therapeutic implications in the management of patients with severe hyponatremia.

Aripiprazole's low intrinsic activities at human dopamine D2L and D2S receptors render it a unique antipsychotic.

Aripiprazole is the first clinically approved atypical antipsychotic agent having dopamine D2 receptor partial agonist activities. To evaluate aripiprazole's agonist and antagonist properties, we established a Chinese hamster ovary cell line expressing high and low densities of the long and short isoforms of human dopamine D2 receptors, then compared its properties with 7-{3-[4-(2,3-dimethylphenyl)piperazinyl]propoxy}-2(1H)-quinolinone (OPC-4392), S(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine ((-)-3-PPP), and terguride (other partial agonists) using forskolin-stimulated cAMP accumulation as an index. In cells expressing high receptor densities, all partial agonists predominantly behaved as agonists. However, in cells expressing low receptor densities, the partial agonists showed significantly lower maximal effects than dopamine. Aripiprazole showed the lowest intrinsic activities. In addition, all compounds blocked the action of dopamine with a maximum effect equal to that of each compound alone. Aripiprazole's low intrinsic activities may account for the clinical finding that, unlike the other partial agonists, it is substantially active against both positive and negative symptoms of schizophrenia.

Novel selective hindlimb vasodilators: synthesis and biological activity of 1-acyl-4-aminopiperidine derivatives.

A series of 6-(4-amino-1-piperidinyl)carbonyl-2(1H)-quinolinones, and their open form derivatives, were synthesized and evaluated for their ability to stimulate femoral artery blood flow (FBF) in the canine hindlimb. All members of this series stimulated FBF, and subsequent experiments revealed that selected members of this series produced minimal changes in coronary blood flow or systemic blood pressure. Compound 25 was the most promising agent in this respect, and clinical trials are now ongoing to evaluate the effectiveness of this drug as a novel treatment for intermittent claudication and Raynaud's phenomenon.

Characterization of orally active nonpeptide vasopressin V(2) receptor agonist. Synthesis and biological evaluation of both the (5R)- and (5S)-enantioisomers of 2-[1-(2-Chloro-4-pyrrolidin-1-yl-benzoyl)-2,3,4,5-tetrahydro-1H-1-benzazepin- 5-yl]-N-isopropylacetamide.

The synthesis and evaluation of both the (R)- and (S)-enantioisomers about the 5-position on a tetrahydro-1H-1-benzazepine derivative were described. The absolute configuration of the (R,R)-isomer (10) was determined by X-ray crystallographic analysis. After evaluation of both enantiomers (compounds R-2, S-2) for binding affinity, cAMP accumulation, and an in vivo study using Brattleboro rats, R-2 showed more potent activity as a V(2) receptor agonist than S-2.

Cilostazol reduces brain lesion induced by focal cerebral ischemia in rats--an MRI study.

To investigate the effects of cilostazol on the hemispheric ischemic lesion, we monitored the apparent diffusion coefficient (ADC) and T2 images by MRI techniques in comparison with histology at the terminal of and after 24-h reperfusion following 2-h occlusion of middle cerebral artery (MCA). The ADC values of tissue water and T2-weighted images were quantified by high field magnetic resonance. No significant difference was observed by ADC image among vehicle and cilostazol treatment groups when measured during MCA occlusion. Oral treatment with cilostazol 30 mg/kg two times at 5 min and 4 h significantly suppressed the hemispheric lesion area and volumes when detected by ADC, T2 images and histology, but 3 and 10 mg/kg cilostazol were without effect. Cilostazol (30 mg/kg) significantly reduced the increased cerebral water content at the ischemic hemisphere compared with vehicle group. In line with these results, the neurological deteriorations were much improved in the cilostazol-treated group. Taken together, it is concluded that post-treatment with cilostazol exerts a potent protective effect against cerebral infarct size by reducing the cytotoxic edema.

Inhibitory effect of pranidipine on N-type voltage-dependent Ca2+ channels in mice.

We investigated the N-type voltage-dependent calcium channel blocking action of pranidipine, a novel dihydropyridine (DHP) derivative. Pranidipine significantly suppressed KCl-induced intracellular calcium changes ([Ca(2+)](i)) in a dose-dependent fashion in dorsal root ganglion neurons. A patch-clamp investigation revealed a dose-dependent blocking effect on N-type currents. Intrathecal injection of pranidipine significantly shortened the licking time in the late phase of the formalin test, as occurs with cilnidipine and amlodipine, which act on L- and N-type channels. Conversely, nicardipine, which acts exclusively on L-type channels, had no antinociceptive effect. Our results indicate that pranidipine inhibits N-type calcium channels. Furthermore, it exerts an antinociceptive effect, which might be related to an attenuation of synaptic transmission by nociceptive neurons due to the blocking effect of pranidipine on N-type calcium channels in primary nociceptive afferent fibers.

Nitric oxide (NO) is not involved in accentuated antagonism for chronotropy in the isolated mouse atrium.

Nitric oxide (NO) is reportedly involved in accentuated antagonism in the canine blood-perfused sinoatrial (SA) node, and is thought to modulate cholinergic control of heart rate in rabbits. In the present study, we evaluated the involvement of NO in accentuated antagonism in an isolated preparation of both atria from C57BL/6J mice. Isoprenaline (10(-10) M-10(-7) M) had positive chronotropic effects but decreased rather than increased contraction strength. Carbachol (10(-8) M-3x10(-6) M) had a concentration-dependent, negative chronotropic action. In the presence of a submaximal concentration of isoprenaline (30 nM), the same concentration range of carbachol elicited a larger decrease in heart rate than in the absence of isoprenaline. The larger decrease in heart rate (accentuated antagonism) was not modified by the presence of the NO synthase inhibitor N(omega)-nitro-L-arginine methylester (L-NAME). Similar results were obtained using ICR strain mice. Isoprenaline increased cAMP content but not cGMP; carbachol in the presence of isoprenaline increased cGMP but had no further effects on cAMP. In the presence of L-NAME, the increase in cGMP elicited by carbachol was attenuated. In the isolated mouse atria, it appears that NO is not involved in accentuated antagonism due to lack of coupling between cGMP signalling and chronotropic function.

A method for evaluating drug effects on intermittent claudication using a treadmill in rats with unilateral hindlimb artery occlusion.

INTRODUCTION: We have developed an in vivo experimental model for evaluating peripheral arterial insufficiency and predicting the efficacy of drugs on intermittent claudication (IC). We found that rats that had been running normally on a treadmill developed a gait disturbance when a hindlimb artery was unilaterally occluded. We hypothesized that the distance run before gait disturbance developed (DGD) in rats with occlusion of a hindlimb artery might be an appropriate index of the severity of peripheral insufficiency, and that the model might serve as a test bed for evaluating drug efficacy. To prove this hypothesis, we examined whether DGD was determined by severity of hindlimb ischemia. Furthermore, we also examined whether cilostazol, which has been proved to have ameliorative effects in patients with IC, increased DGD. METHODS: To vary the severity of ischemia, either the superficial femoral artery, the distal portion of the iliac artery, or the proximal portion of iliac artery was unilaterally occluded. After a recovery period, these rats were subjected to a treadmill test (15 m/min and 15% incline) to determine DGD and examine the effect of cilostazol on DGD. RESULTS: DGD was the longest and shortest in rats with superficial femoral artery and proximal portion of iliac artery occlusion, respectively. Intermediate DGD was observed in rats with distal portion of iliac artery occlusion. These data suggest that DGD is correlated with the severity of hindlimb ischemia. Two weeks or longer administration of cilostazol 30 and 100 mg/kg twice a day evoked a significant increase in DGD. DISCUSSION: Peripheral arterial insufficiency and its modulation by drugs can be evaluated in rats with unilateral hindlimb artery occlusion, on a treadmill, by measuring DGD.

A flow cytometric method for determination of the interferon receptor IFNAR2 subunit in peripheral blood leukocyte subsets.

INTRODUCTION: It is expected that expression levels in the peripheral blood mononuclear cells (PBMC) of IFNAR2, a subunit of the interferon (IFN) receptor, may be a marker for predicting IFN response. In the present study, we have established a rapid and convenient method for assaying IFNAR2, using flow cytometry. METHODS: Fifty microliters of whole blood from healthy volunteers was treated with an anti-IFNAR2 antibody and stained with a Fluorescein isothiocyanate (FITC)-conjugated secondary antibody. In addition, the cells were stained with subset-specific antibodies conjugated with phycoerythrin (PE) and PE covalently linked to cyanin 5 at the same time. The mean FITC-fluorescence intensities were analyzed separately by gating on subset-specific regions. RESULTS: IFNAR2 was detected in most lymphocytes, monocytes, and granulocytes, although IFNAR2 expression was higher in the monocytes and granulocytes than in the lymphocytes. The intra- and interdaily variations of IFNAR2 in lymphocytes, monocytes, and granulocytes were small. Among the lymphocyte subsets, IFNAR2 showed high expression in natural killer (NK) cells and low expression in T lymphocytes. The effect of IFN-alpha on IFNAR2 expression was examined in vitro. A down-regulation of IFNAR2 was observed by IFN-alpha above 100 IU/ml. DISCUSSION: This assay may be useful for examining IFNAR2 in various leukocyte subsets, separately, as well as providing a rapid and easy method for monitoring expression of type I IFN receptors.