Characterization of Aldosterone-producing Cell Cluster (APCC) at Single-cell Resolution

CONTEXT

The adrenal cortex consists of zona glomerulosa (ZG), fasciculata (ZF), and reticularis. Aldosterone-producing cell clusters (APCCs) that strongly express aldosterone synthase (CYP11B2) are frequently found in adult adrenals and harbor somatic mutations that are also detected in aldosterone-producing adenomas (APAs). Primary aldosteronism is mainly caused by APAs or idiopathic hyperaldosteronism (IHA). We presume that APCCs are causing IHA and are precursors of APAs. However, the gene expression characteristics and especially the development of APCCs are not well understood.

OBJECTIVE

This study aimed to analyze the transcriptome of APCCs at single-cell resolution and infer the developmental trajectory.

METHODS

Single-cell RNA sequencing (scRNA-seq) of 2 adult adrenals was performed.

RESULTS

Immunohistochemical analyses confirmed the 2 adrenals had APCCs. scRNA-seq data of 2928 adrenal cells were obtained and 1765 adrenocortical cells were identified based on unsupervised clustering and the marker gene expression. The adrenocortical cells were divided into 6 clusters, of which 3 clusters (923 cells) were composed of APCC/ZG cells. By further subclustering, the APCC/ZG cells were divided into 3 clusters (clusters C1, C2, and C3), we finally identified APCC cluster (C3) and ZG cluster (C1). Cluster C2 seemed to be ZG-to-ZF transitional cells. RNA velocity analysis inferred the developmental direction from cluster ZG-cluster-C1 to APCC-cluster-C3. The scRNA-seq additionally revealed that many CYP11B2-positive cells were positive for CYP11B1 and/or CYP17A1, which were essential for cortisol but not for aldosterone production.

CONCLUSIONS

Our results revealed the gene expression characteristics of APCC at single-cell resolution and show that some ZG cells remodel to APCC.

Case Study: A Japanese patient with metastatic renal cell carcinoma who achieved long‐term treatment‐free survival with pembrolizumab and axitinib in the KEYNOTE‐426 phase III trial of pembrolizumab and axitinib versus sunitinib

Introduction

Case presentation

Conclusion

Oncological outcomes of dose reductions in cisplatin due to renal dysfunction for patients with metastatic urothelial carcinoma

Objective

To investigate whether dose reductions in cisplatin due to renal dysfunction were associated with worse clinical outcomes in metastatic urothelial carcinoma (UC) patients.

Patients and methods

One hundred and fifty one metastatic UC patients who received first‐line gemcitabine plus cisplatin (GC) salvage chemotherapy without a previous history of peri‐surgical chemotherapy were included in this retrospective study. Patients with endogenous creatinine clearance of 60 mL/min or more were treated with a full dose of cisplatin, while those with 45‐59 and 30‐44 mL/min were treated with 75% and 50% doses, respectively. Patients were divided into three groups based on the average administered dose of cisplatin of 100% (Group A, N = 43), 99%‐75% (Group B, N = 59), and less than 75% (Group C, N = 49), and therapeutic responses and the toxicity of GC were compared.

Results

Complete response rates were 9.3%, 13.6%, and 14.3% in groups A, B, and C, respectively. One‐year progression‐free survival rates were 22.9%, 31.1%, and 36.7% in groups A, B, and C with no significant differences. One‐year cancer‐specific survival rates were 56.1%, 71.1%, and 68.3% in groups A, B, and C with no significant differences. A multivariate Cox's regression analysis showed that the dose of cisplatin was not an independent prognostic factor for disease progression and cancer death. Furthermore, there were no significant differences in the incidence of severe adverse events.

Conclusions

Dose reductions in cisplatin due to renal dysfunction did not worsen clinical outcomes for metastatic UC.

Efficacy of Nivolumab Plus Ipilimumab in a Patient With Renal Cell Carcinoma Concomitant With Cardiac Metastasis: A Case Report

BACKGROUND/AIM

Patients with metastatic renal cell carcinoma (RCC) with cardiac metastasis have had poor outcomes in the era of molecular targeted therapy. There are few reported outcomes for patients with cardiac metastasis of RCC treated with immune checkpoint inhibitors (ICIs).

CASE REPORT

A 32-year-old female presented with metastatic RCC (unclassified type) with contralateral renal and cardiac metastases, as well as renal hilar lymph node metastases (cT4N2M1). An ¹⁸F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) computed tomographic (CT) scan was useful in diagnosing cardiac metastasis. Nivolumab plus ipilimumab achieved prominent shrinkage of almost all tumors except for one cardiac tumor. FDG-PET/CT scan also revealed the marked attenuation of FDG uptake in each tumor. In addition, a needle biopsy of the remaining primary renal tumor was pathologically observed to have no viable cancer cells.

CONCLUSION

This successful case suggests that ICIs might provide a better outcome even for patients with cardiac metastasis of RCC, and that FDG-PET/CT scan might be useful for therapeutic assessment, as well as diagnosis.

A case of castration-resistant prostate cancer with liver metastases achieved a complete response by docetaxel chemotherapy

Castration-resistant prostate cancer (CRPC) patients with liver metastases have an extremely poor prognosis. Herein, we report a rare patient who achieved a complete response by docetaxel chemotherapy for this aggressive disease. A 67-year-old Japanese male diagnosed with local prostate cancer [initial prostate specific antigen (PSA) of 10.3 ng/mL, a highest Gleason score of eight] received radical prostatectomy (RP) followed by salvage radiotherapy for PSA recurrence without distant metastases. After four years, androgen deprivation therapy was commenced for both local recurrence and elevated PSA. After a further four years, despite good control of PSA (1.2 ng/mL), other clinical findings including radiographic images revealed CRPC with multiple liver metastases. Ten cycles of docetaxel chemotherapy achieved a complete response for more than five years. In conclusion, even if a patient has CRPC with liver metastases, early diagnostic imaging irrespective of the PSA level may provide a better response to early docetaxel chemotherapy.

A case in which bladder cancer invaded the ureteral orifice and was resected via photodynamic diagnosis-assisted transurethral resection involving orally administered 5-aminolevulinic acid

INTRODUCTION

Transurethral resection of bladder tumor is widely used in combination with photodynamic diagnosis to treat non-muscle invasive bladder cancer. We experienced an intriguing case, in which bladder cancer infiltrated into the right ureteral orifice and was resected via photodynamic diagnosis-assisted transurethral resection involving the oral administration of 5-aminolevulinic acid.

CASE PRESENTATION

This case was a 71-year-old Japanese man. He was diagnosed with bladder carcinoma, which had infiltrated into the right ureter (clinical classification: T1, N0, M0). He underwent transurethral resection involving the oral administration of 5-aminolevulinic acid. We successfully resected the tumor in the ureteral orifice, which was accomplished by resecting the ureteral orifice until the non-luminescent lumen was exposed. After the surgery, to prevent recurrence, Bacillus Calmette-Guérin was administered intravesically after right ureteral stent placement.

CONCLUSION

Photodynamic diagnosis-assisted transurethral resection involving the oral administration of 5-aminolevulinic acid has the potential to treat ureteral tumors derived from bladder tumors.

Meningeal carcinomatosis from bladder cancer: A case report and review of the literature

A 66-year-old Japanese male patient was referred to Saitama Medical University International Medical Center for treatment of bladder cancer (clinical stage T2 or higher without metastasis), and underwent radical cystectomy with pelvic lymphadenectomy. The histopathological diagnosis was high-grade urothelial carcinoma (pathological stage T2bN2, ly1, v0) and 2 cycles of adjuvant systemic chemotherapy (gemcitabine plus cisplatin) were administered. At 15 months after the operation, mediastinal and lung hilar lymph nodes and multiple bone metastases were identified on computed tomography imaging. After 3 cycles of the previous regimen as salvage systemic chemotherapy, the lymph node metastases had shrunk and the bone metastases were stable; therefore, further chemotherapy was planned. At 26 days after the initiation of the 4th cycle, the patient felt nausea and lower limb weakness. Spinal and brain magnetic resonance imaging with contrast medium revealed diffuse enhancement at the surface of the spinal cord and brain. In addition, abnormal signal intensity in the subarachnoid space was observed on fluid-attenuated inversion recovery imaging; therefore, the patient was diagnosed with meningeal carcinomatosis (MC). Treatment, including whole-brain radiotherapy, was planned for MC; however, the patient's condition rapidly worsened and he succumbed to the disease 14 days after the diagnosis of MC. The definitive diagnosis of MC was confirmed at autopsy.

Long-term efficacy and safety results from an open-label phase III study (UNCOVER-J) in Japanese plaque psoriasis patients: impact of treatment withdrawal and retreatment of ixekizumab

Background

Long‐term management of moderate‐to‐severe psoriasis is usually discussed in terms of continuous administration; however, there are many situations in clinical practice where treatment may be withdrawn with subsequent retreatment.

Objective

To assess the clinical course after ixekizumab treatment withdrawal and retreatment, as well as the effectiveness of ixekizumab retreatment, in Japanese patients with plaque psoriasis.

Methods

This single‐arm, open‐label study (UNCOVER‐J; NCT01624233) comprised 78 patients with plaque psoriasis. After ixekizumab treatment (160‐mg loading dose, 80 mg every 2 weeks for the first 12 weeks, and then 80 mg every 4 weeks (IXE Q4W) until Week 52), 70 patients achieved a Psoriasis Area Severity Index (PASI)75 response at Week 52. These 70 patients withdrew from ixekizumab treatment from Weeks 52 to 100. Patients who relapsed (PASI ≤50) during the Treatment Withdrawal Period were retreated with IXE Q4W for 192 weeks.

Results

At Weeks 52, 76 and 100, PASI75 response rates were 100%, 26% and 7%; PASI90 response rates were 87%, 11% and 3%; and PASI100 response rates were 53%, 0% and 0%. After treatment withdrawal, 87% of patients relapsed; median time to relapse was 143 days. After 12 weeks of retreatment with IXE Q4W, 83% of relapsed patients achieved PASI75, 68% achieved PASI90 and 25% achieved PASI100; improvements were maintained up to 120 weeks of retreatment. Treatment‐emergent adverse events and serious adverse events were reported in 56% and 4% of patients during the Treatment Withdrawal Period, and in 88% and 14% of patients during the Retreatment Period.

Conclusion

In patients withdrawn from ixekizumab after achieving PASI75, approximately half relapsed within 5 months of withdrawal; however, most patients recaptured response within 12 weeks, and response was maintained for up to 120 weeks of retreatment.

The sociobiology of everyday life : A new look at a very old novel

The 1000-year-old novel The Tale of Genji, written by Murasaki Shikibu around 1002 CE, shows the operation of general principles of sociobiology. Isolated from western influences and cloaked in Japanese traditions, the common traits associated with reproductive processes are clearly evident. The novel depicts the differential investment of males and females in offspring, male competitive behaviors, and concerns for paternity, kin selection, reciprocal social exchange, species-typical emotional expression, female mate choice, positive assortative mating, and acknowledgment of hereditary transmission of physical and psychological traits. The nature of human behavior in Genji's time seems little different than now and has all the attributes of species-specific and universal traits. Indeed, it can be argued that the fundamental characteristics of Homo sapiens have never changed, being influenced only in form by culture. The qualitative and quantitative evaluation of ancient texts is a strong methodology for understanding the invariant nature of human behavior.

Clinical features and risk factors for developing varicella zoster virus dissemination following hematopoietic stem cell transplantation

BACKGROUND

We retrospectively analyzed 80 instances of varicella zoster virus (VZV) disease in 72 patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) and examined the clinical differences between localized and disseminated disease. Risk factors for developing VZV dissemination were also evaluated.

RESULTS

Of the 80 instances, 54 instances were localized diseases and 26 were disseminated diseases. Patient characteristics did not differ significantly between the 2 groups, except for the first-line therapy and the duration from symptom onset to treatment. In the disseminated group, intravenous acyclovir was used as the first-line therapy more frequently, and more time elapsed before beginning antiviral therapy compared with the localized group. In multivariate analyses, the duration from symptom onset to treatment was identified as an independent risk factor that significantly affected the development of VZV dissemination. Gender, total body irradiation, and chronic graft-versus-host disease, of which the latter 2 factors were reported as risk factors for the development of VZV disease after HSCT, did not affect the development of VZV dissemination.

CONCLUSION

Our results suggest that VZV infection or reactivation may easily progress to viremia with delayed use of antiviral agents and may result in VZV dissemination in immunocompromised patients.

Polypyrrole-modified tips for functional group recognition in scanning tunneling microscopy

Tailored chemical modification of scanning tunneling microscopy (STM) tips is a promising method for the recognition of specific chemical species and functional groups in STM images. The present study shows for the first time that tips modified with polypyrrole can be used to measure STM images with molecular resolution. A high conductivity of the polypyrrole film was found to be important for the observation of STM images, while the thickness of the polymer film did not affect the images significantly. Furthermore, it was shown that recognition of functional groups in STM images is possible with tips coated with conductive polypyrroles. 1-Octadecanol and 1-octadecanoic acid monolayers with polypyrrole-modified tips gave high-resolution STM images in which aligned OH and COOH residues were represented by easily recognizable elevated bands. These selective contrast enhancements resemble those observed by us previously with gold tips modified with self-assembled monolayers (SAMs) and seem to be due to hydrogen bond interactions between functional groups of the tip-modifying molecules and the sample. The reproducibility of contrast enhancements in this study was significantly higher than for SAM-modified tips, suggesting that polymer modification of STM tips is particularly promising for specific functional group recognition with chemically modified STM tips.

Ebastine inhibits T cell migration, production of Th2-type cytokines and proinflammatory cytokines

BACKGROUND

Cytokine imbalance and cellular migration to inflammatory sites are critical components of allergic diseases. Redirecting cytokine imbalance and inhibiting cell migration therefore represent important therapeutic strategies for the treatment of these disorders.

OBJECTIVES

To study the in vitro effect of ebastine, a novel non-sedating H1 receptor antagonist, on cytokine secretion and migration of activated T cells, as well as production of pro-inflammatory cytokines by macrophages.

METHODS

Peripheral T cells obtained from healthy volunteers were cultured in wells coated with the combination of anti-CD3 monoclonal antibody (mAb) and anti-CD26 mAb, anti-CD3 mAb and anti-CD28 mAb, or anti-CD3 mAb with PMA, in the presence or absence of ebastine. T cell proliferation and the production of cytokines were measured by [3H]thymidine incorporation assay and ELISA, respectively. In addition, transendothelial migration of T cells and production of pro-inflammatory cytokines by macrophages were examined.

RESULTS

Ebastine inhibited T cell proliferation and the production of IL-4, IL-5, IL-6, and TNF-alpha by T cells under each co-stimulatory condition tested, whereas it exhibited no effect on the production of IL-2 or IFN-gamma. In addition, T cell migration and the production of such pro-inflammatory cytokines as TNF-alpha and IL-6 by macrophages were inhibited by ebastine.

CONCLUSIONS

These results indicate that ebastine has a specific inhibitory effect on Th2-type cytokine production. Moreover, ebastine inhibited T cell migration and pro-inflammatory cytokine production by T cells and macrophages, suggesting that ebastine might be useful for the treatment of T cell-mediated allergic inflammatory disorders, including asthma, atopic dermatitis, and Th2-type autoimmune diseases.

The role of CH/pi interactions implicated in the sequence-dependent deformability of DNA

The crystal structure of AT-rich deoxynucleotides was retrieved from the Nucleic Acid Database and analyzed with the use of our program CHPI. It has been found that the thymidine 5-methyl group favorably interacts with an adenine ring in the same strand. Since an AT sequence is accompanied with another AT in the complementary strand, the interaction is duplicated, thus forming a twin CH/pi interaction. An AT step becomes stickier than other sequences by the above network. A number of CH/pi contacts have also been found in the crystal structure of A-tract. A successive N/T-methyl stacking in the same strand may contribute in making these steps robust and straight. The role of methyl groups in modified DNA has been discussed on a similar basis.

Therapeutic guidelines for the treatment of generalized pustular psoriasis (GPP) based on a proposed classification of disease severity

Generalized pustular psoriasis (GPP) is a rare but notoriously recalcitrant cutaneous diseases. Therefore, there have been few reports of more than ten patients with GPP who were treated at the same institution. The severity of this disease and its response to each therapeutic modality vary among patients. In some GPP is life-threatening, but in others it may show a benign, chronic course for a long period of time. Before starting treatment, a knowledge of the therapeutic efficacy and side effects of each drug used in the treatment of GPP is necessary. In our multicenter study, we compared the effectiveness of and adverse reactions to several systemically administered drugs. Following the development of a unique classification of the disease severity based on scoring the clinical symptoms and the laboratory findings, we propose here therapeutic guidelines for the treatment of GPP.

Noninvasive imaging of protein-protein interactions in living subjects by using reporter protein complementation and reconstitution strategies

In this study we have developed bioluminescence-imaging strategies to noninvasively and quantitatively image protein-protein interactions in living mice by using a cooled charge-coupled device camera and split reporter technology. We validate both complementation and intein-mediated reconstitution of split firefly luciferase proteins driven by the interaction of two strongly interacting proteins, MyoD and Id. We use transient transfection of cells and image MyoD-Id interaction after induction of gene expression in cell culture and in cells implanted into living mice. Techniques to study protein-protein interactions in living subjects will allow the study of cellular networks, including signal transduction pathways, as well as development and optimization of pharmaceuticals for modulating protein-protein interactions.

Protein splicing-based reconstitution of split green fluorescent protein for monitoring protein-protein interactions in bacteria: improved sensitivity and reduced screening time

In this research, an improved detection system is described that allows an easy in vivo screening and selection of functional interactions between two interacting proteins in bacteria. We earlier reported a new concept for detecting protein-protein interactions based on reconstitution of split-enhanced green fluorescent protein (EGFP) by protein splicing (Ozawa, T.; et al. Anal. Chem. 2000, 72, 5151-5157.): Two putative interacting proteins are genetically fused to the split VDE inteins, which are linked directly to the N- and C-terminal halves of the split EGFP. Association of the interacting proteins results in functional complementation of VDE and protein-splicing reaction that leads to formation of an EGFP fluorophore. This technique simplified detection of protein interactions, but because of the low splicing efficiency of VDE intein, its sensitivity and screening time were not enough for detecting the protein interactions directly in living cells. In this paper, we have explored the use of the DnaE split intein from Synechocystis sp. PCC6803 for intracellular reconstitution of the split EGFP. We examined efficiency of the fluorophore formation by preparing four different split-EGFP types, among which EGFP dissected at the position between 157 and 158 was found to show the strongest fluorescence intensity upon protein interactions. A time required for the formation of EGFP after protein interactions was only 4 h, as compared to 3 days with the VDE intein. The protein interactions were thereby detected by an in vivo selection and screening assay in Escherichia coli on Luria broth agar plates. This improvement permits versatile designs of screening procedures either for ligands that bind to particular proteins or for molecules or mutations that block particular interactions between two proteins of interest.

Detection of protein-protein interactions in vivo based on protein splicing

In mammalian cells, protein-protein interactions constitute essential regulatory steps that modulate the activity of signaling pathways. In recent years, several approaches towards understanding the interactions have been developed. We describe herein a new method for detecting protein-protein interactions in vivo based on protein splicing and highlight some potential applications of this technique.

Influence of natural, electrically neutral lipids on the potentiometric responses of cation-selective polymeric membrane electrodes

Ionophore-free ion exchanger electrodes were found to exhibit quite a high selectivity for the creatininium ion; however, measurements in diluted urine samples revealed large emf drifts. Potentiometric, chromatographic, NMR, and mass spectrometric evidence did not reveal any major cationic interfering agents, and anionic interfering agents cannot trivially explain the consistently positive emf drifts. Ultrafiltration of urine samples showed that the interfering agents have molecular weights below 1000 u. The drifts are apparently caused by electrically neutral lipophilic compounds of low molecular weight that are easily extracted into organic phases. Follow-up experiments showed that p-cresol and cholesterol cause no significant emf responses but that coproporphyrin, phosphatidylserine, taurocholic acid, cholic acid, phosphatidylethanolamine, and octanoic acid cause positive emf drifts of the type that was observed with the urine samples. The extent of the responses and the response time depend not only on the specific compound but also on the cation in the sample solution. These results suggest that the emf drifts are due to extraction of such natural lipids into the organic membrane phase where they interact in an ionophore-like fashion with the analyte and interfering ions. Changes in the potentiometric selectivities after contact with natural lipids support this interpretation. The same effect of natural lipids is also expected for ionophore-based electrodes. Indeed, exposure of a valinomycin-based electrode to a methylene chloride extract of urine resulted in a significant reduction of the Na+ discrimination, increasing log Kpot(K,Na) from -3.9 to -3.1.

Threshold ionic site concentrations required for Nernstian potentiometric responses of neutral ionophore-incorporated ion-selective liquid membranes

An equation that can describe the concentrations of ionic sites required for a Nernstian potentiometric response slope of neutral ionophore-incorporated ion-selective liquid membranes is presented. This equation is derived from a model based on electrical diffuse layers on both the membrane and the aqueous sides of the interface, in which the phase boundary potential is correlated to the surface charge density as well as the salt concentrations in the bulk membrane and aqueous solution. To experimentally and accurately confirm the validity of this equation, response characteristics of field effect transistors covered by neutral ionophore-based liquid membranes with varying concentrations of a derivative of tetraphenylborate as an anionic site but free of ionic impurities were examined. The observed membrane potentials and the response slopes for membranes with various concentrations of anionic sites were in good agreement with the values calculated from the theory presented in this paper with the measured complexation stability constants for the relevant systems. This result indicates that the theoretical prediction based on the proposed equation for the anionic site concentration is accessible for the preparation of neutral ionophore-incorporated ion-selective liquid membranes, which show Nernstian response slopes for the primary ions.

Imaging of conformational changes of proteins with a new environment-sensitive fluorescent probe designed for site-specific labeling of recombinant proteins in live cells

We demonstrate herein a new method for imaging conformational changes of proteins in live cells using a new synthetic environment-sensitive fluorescent probe, 9-amino-6,8-bis(1,3,2-dithioarsolan-2-yl)-5H-benzo[a]phenoxazin-5-one. This fluorescent probe can be attached to recombinant proteins containing four cysteine residues at the i, i + 1, i + 4, and i + 5 positions of an alpha-helix. The specific binding of the fluorescent probe to this 4Cys motif enables fluorescent labeling inside cells by its extracellular administration. The high sensitivity of the fluorophore to its environment enables monitoring of the conformational changes of the proteins in live cells as changes in its fluorescence intensity. The present method was applied to calmodulin (CaM), a Ca2+-binding protein that was well-known to expose hydrophobic domains, depending on the Ca2+ concentration. A recombinant CaM fused at its C-terminal with a helical peptide containing a 4Cys motif was labeled with the fluorescent probe inside live cells. The fluorescence intensity changed reversibly depending on the intracellular Ca2+ concentration, which reflected the conformational change of the recombinant CaM in the live cells.

Optical detection in microscopic domains. 2. Inner filter effects for monitoring nonfluorescent molecules with fluorescence

In this research, we test whether optical detection techniques show different characteristics in microscopic solution volumes (nano-, pico-, and femtoliter range) compared to the usual macroscopic samples. In part 1 (Lu, H.; et al. Anal Chem. 2000, 72, 1569-1576.) absorption spectra of high quality were obtained, quantitatively obeying both Beer-Lambert's law and the law of superposition, despite the micrometer optical path lengths and the curvatures of the droplets studied. Addition and subtraction of absorbing molecules with diffusional microburets (DMBs), as well as more complex operations (simultaneous addition of one and subtraction of another molecule, and a consuming scheme), have been monitored with good spectral and temporal resolution. Despite the unexpectedly good performance of absorption microspectrometry, fluorescence-based detection schemes are considered more sensitive for microscopic studies (e.g., cell physiology). In this paper, we test whether fluorescence-based schemes can be used to indirectly measure nonfluorescent chemicals in microscopic domains. Absorption by such molecules will cause a corresponding decrease in overall fluorescence intensity of the added standard fluorescent dye. This phenomenon, the inner filter effect (IFE), was tested using Lucifer Yellow CH (LY) as the fluorescent standard dye. Its effective irradiation was absorbed by Orange G (primary IFE) or its emission by Bromophenol Blue (secondary IFE). By utilizing these phenomena, (1) we measured the concentration of absorbing molecules in microscopic samples by adding a standard amount of LY by a DMB, and (2) we monitored DMB delivery of nonfluorescent reagents into droplets preloaded with LY. The results prove that IFEs are sensitive indirect means of detection of absorbing molecules in microscopic domains. The techniques presented are expected to find applications in cellular studies where absorption spectrometry is usually not considered.

Studies on the matched potential method for determining the selectivity coefficients of ion-selective electrodes based on neutral ionophores: experimental and theoretical verification

A theory is presented that describes the matched potential method (MPM) for the determination of the potentiometric selectivity coefficients (KA,Bpot) of ion-selective electrodes for two ions with any charge. This MPM theory is based on electrical diffuse layers on both the membrane and the aqueous side of the interface, and is therefore independent of the Nicolsky-Eisenman equation. Instead, the Poisson equation is used and a Boltzmann distribution is assumed with respect to all charged species, including primary, interfering and background electrolyte ions located at the diffuse double layers. In this model, the MPM-selectivity coefficients of ions with equal charge (ZA = ZB) are expressed as the ratio of the concentrations of the primary and interfering ions in aqueous solutions at which the same amounts of the primary and interfering ions permselectively extracted into the membrane surface. For ions with unequal charge (ZA not equal to ZB), the selectivity coefficients are expressed as a function not only of the amounts of the primary and interfering ions permeated into the membrane surface, but also of the primary ion concentration in the initial reference solution and the delta EMF value. Using the measured complexation stability constants and single ion distribution coefficients for the relevant systems, the corresponding MPM selectivity coefficients can be calculated from the developed MPM theory. It was found that this MPM theory is capable of accurately and precisely predicting the MPM selectivity coefficients for a series of ion-selective electrodes (ISEs) with representative ionophore systems, which are generally in complete agreement with independently determined MPM selectivity values from the potentiometric measurements. These results also conclude that the assumption for the Boltzmann distribution was in fact valid in the theory. The recent critical papers on MPM have pointed out that because the MPM selectivity coefficients are highly concentration dependent, the determined selectivity should be used not as "coefficient", but as "factor". Contrary to such a criticism, it was shown theoretically and experimentally that the values of the MPM selectivity coefficient for ions with equal charge (ZA = ZB) never vary with the primary and interfering ion concentrations in the sample solutions even when non-Nernstian responses are observed. This paper is the first comprehensive demonstration of an electrostatics-based theory for the MPM and should be of great value theoretically and experimentally for the audience of the fundamental and applied ISE researchers.

Relationship between lymphocyte cyclosporin sensitivity and clinical progress of psoriasis

Cyclosporin (CYA) is a therapeutic agent used in the treatment of psoriasis vulgaris. However, the effectiveness of CYA therapy varies among patients. In the present study, due to the fact that CYA mainly acts on lymphocytes, we hypothesized that a measurement of the sensitivity of lymphocytes to CYA in vitro (IC50) could be applied to patients with psoriasis vulgaris to determine therapeutic success. We measured IC50 levels of 32 patients presenting with psoriasis prior to CYA administration, and classified them into three groups according to IC50 levels: favorable, moderate and low sensitivity. CYA sensitivity levels were correlated with the degree of improvements in psoriasis area and severity index (PASI) scores, CYA dosage and occurrence of side-effects (hepatopathy and nephropathy). Results showed the degree of improvement in PASI scores differed significantly between the favorable and low sensitivity groups (P < 0.05). Furthermore, CYA dosage was lowest in the favorable sensitivity group and highest in the low sensitivity group. Moreover, hepatopathies and nephropathies were detected in the low and moderate sensitivity groups, but not in the favorable sensitivity group. These results suggest that the effectiveness of CYA therapy as a treatment of psoriasis vulgaris is affected by the sensitivity of lymphocytes in each patient.

Split luciferase as an optical probe for detecting protein-protein interactions in mammalian cells based on protein splicing

We describe a new method for detecting protein-protein interactions in intact mammalian cells; the approach is based on protein splicing-induced complementation of rationally designed fragments of firefly luciferase. The protein splicing is a posttranslational protein modification through which inteins (internal proteins) are excised out from a precursor fusion protein, ligating the flanking exteins (external proteins) into a contiguous polypeptide. As the intein, naturally split DnaE from Synechocystis sp. PCC6803 was used: The N- and C-terminal DnaE, each fused respectively to N- and C-terminal fragments of split luciferase, were connected to proteins of interest. In this approach, protein-protein interactions trigger the folding of DnaE intein, wherein the protein splicing occurs and thereby the extein of ligated luciferase recovers its enzymatic activity. To test the applicability of this split luciferase complementation, we used insulin-induced interaction between known binding partners, phosphorylated insulin receptor substrate 1 (IRS-1) and its target N-terminal SH2 domain of PI 3-kinase. Enzymatic luciferase activity triggered by insulin served to monitor the interaction between IRS-1 and the SH2 domain in an insulin dose-dependent manner, of which amount was assessed by the luminescent intensity. This provides a convenient method to study phosphorylation of any protein or interactions of integral membrane proteins, a class of molecules that has been difficult to study by existing biochemical or genetic methods. High-throughput drug screening and quantitative analysis for a specific pathway in tyrosine phosphorylation of IRS-1 in insulin signaling are also made possible in this system.

Potentiometric responses of polymeric liquid membranes based on hydrophobic chelating agents to metal ions

The effect of hydrophobicity of acidic chelating agents as sensing materials on the potentiometric responses of polymeric liquid membranes was investigated. The chelating agents tested were 8-quinolinol (HOx), dithizone (HDz), 1-(2-pyridylazo)-2-naphthol (PAN) and their alkylated analogues, 5-octyloxymethyl-8-quinolinol (HO8Q), di(phexylphenyl)thiocarbazone (C6HDz), 7-pentadecyloxy-1-(2-pyridylazo)-2-naphthol (C15PAN) and a series of N-alkylcarbonyl-N-phenylhydroxylamines (CnPHA, n = 3, 6, 9, 12). The distribution coefficients between membrane solvent and water were determined to evaluate the hydrophobicity of the agents. The potential-pH profiles of the membranes containing hydrophobic chelating agents demonstrated the generation of potentiometric responses, while less hydrophobic agents gave no response. A possible model for the generation of membrane potential is proposed. The charge separation is attained by the permselective uptake of metal cations by the chelating agent anion at membrane/solution interface, where the high hydrophobicity of the agent enables the anionic or deprotonated form of the agents to remain at the membrane/solution interface.

Scanning tunneling microscopy with chemically modified tips: discrimination of porphyrin centers based on metal coordination and hydrogen bond interactions

STM gold tips chemically modified with 4-mercaptopyridine (4MP) were found capable of discriminating zinc(II) 5,15-bis(4-octadecyloxyphenyl)porphyrin (Por-Zn) from its metal-free porphyrin (Por-2H) and nickel(II) complexes (Por-Ni) in the mixed monolayers of these compounds, spontaneously formed at the solution/graphite interface. The porphyrin centers in STM images observed with 4MP-modified tips exhibited bright spots, while those measured with unmodified tips exhibited the porphyrin centers as dark depressions. The centers of Por-Zn were brighter than those of Por-2H and Por-Ni, thereby allowing the discrimination of Por-Zn from Por-2H or Por-Ni in mixed monolayers. The changes in the contrasts of porphyrin centers of Por-2H and Por-Zn/ Por-Ni were explained by facilitated electron tunneling due to hydrogen bond and metal coordination interactions, respectively, between porphyrin centers and the pyridyl group of 4MP on the tip.

Correlation between cytosolic calcium concentration and degranulation in RBL-2H3 cells in the presence of various concentrations of antigen-specific IgEs

We studied the dependence of beta-hexosaminidase release from RBL-2H3 cells on the antigen-specific IgE concentrations. The cells were sensitized with DNP-specific IgE (0.5-5000 ng/ml) or OVA-specific IgE (5-50 ng/ml) and stimulated with DNP(35)-HSA (10(-2)-100 ng/ml) or OVA (10(-1) ng/ml-10 microg/ml). It was found that the beta-hexosaminidase release increased in a dose-dependent manner with the concentration of the IgEs and antigens added to the mast-cell suspension. We also studied the correlation between the intracellular calcium concentration ([Ca(2+)]i) and degranulation in RBL-2H3 cells. The percentage of beta-hexosaminidase release from the cells was well correlated with [Ca(2+)](i) increase, and the correlation coefficient was 0.88 for DNP-specific IgE and 0.99 for OVA-specific IgE. The minimum [Ca(2+)](i) required to induce the beta-hexosaminidase release was 100 nM for DNP-specific IgE, and 70 nM for OVA-specific IgE. Therefore, the [Ca(2+)](i) monitoring system is a sensitive marker of degranulation from RBL-2H3 cells and can be used to measure even low amounts of antigen-specific IgE.

Fluorescent indicators for cyclic GMP based on cyclic GMP-dependent protein kinase Ialpha and green fluorescent proteins

We describe herein fluorescent indicators for cyclic GMP (cGMP) in single living cells. cGMP-dependent protein kinase Ialpha (PKG Ialpha), a receptor for cGMP, was fused with blue- and red-shifted green fluorescent proteins (GFPs) to its N- and C-termini, respectively. Using PKG lalpha delta1-47, in which the dimerization domain was deleted, fluorescence resonance energy transfer between the GFPs was found to increase upon cGMP-induced conformational change in PKG Ialpha delta1-47. We demonstrated that thus-developed fluorescent indicators reversibly responded to cGMP that was produced in nitric oxide-stimulated HEK293 cells. The present genetically encoded fluorescent indicators open a way not only for understanding the dynamics of cGMP signaling in single cells and organisms but also for discovering pharmaceuticals such as isoform-specific inhibitors for phosphodiesterases.

How can Ca2+ selectively activate recoverin in the presence of Mg2+? Surface plasmon resonance and FT-IR spectroscopic studies

We investigated the relationship between metal ion selective conformational changes of recoverin and its metal-bound coordination structures. Recoverin is a 23 kDa heterogeneously myristoylated Ca(2+)-binding protein that inhibits rhodopsin kinase. Upon accommodating two Ca(2+) ions, recoverin extrudes a myristoyl group and associates with the lipid bilayer membrane, which was monitored by the surface plasmon resonance (SPR) technique. Large changes in SPR signals were observed for Sr(2+), Ba(2+), Cd(2+), and Mn(2+) as well as Ca(2+), indicating that upon binding to these ions, recoverin underwent a large conformational change to extrude the myristoyl group, and thereby interacted with lipid membranes. In contrast, no SPR signal was induced by Mg(2+), confirming that even though it accommodates two Mg(2+) ions, recoverin does not induce the large conformational change. To investigate the coordination structures of metal-bound Ca(2+) binding sites, FT-IR studies were performed. The EF-hands, Ca(2+)-binding regions each comprising 12 residues, arrange to coordinate Ca(2+) with seven oxygen ligands, two of which are provided by a conserved bidentate Glu at the 12th relative position in the EF-hand. FT-IR analysis confirmed that Sr(2+), Ba(2+), Cd(2+), and Mn(2+) were coordinated to COO(-) of Glu by a bidentate state as well as Ca(2+), while coordination of COO(-) with Mg(2+) was a pseudobridging state with six-coordinate geometry. These SPR and FT-IR results taken together reveal that metal ions with seven-coordinate geometry in the EF-hands induce a large conformational change in recoverin so that it extrudes the myristoyl group, while metal ions with six-coordinate geometry in the EF-hands such as Mg(2+) remain the myristoyl group sequestered in recoverin.

CH/pi interactions in the crystal structure of TATA-box binding protein/DNA complexes

Crystal structures of TATA box-binding proteins (TBP) of various sources bound to their promoter DNA (TATA box) were analyzed with use of our program CHPI. A number of short CH/Csp2 contacts have been unveiled in these complexes at the boundary of TBP and the TATA box minor groove. The result was discussed in the context of the CH/pi interaction. Thus, the nature of nonpolar forces, reported in the past at the interface of the two components, has been attributed to the CH/pi interaction. Furthermore, many CH/pi contacts have been disclosed within the same strand of the promoter DNA. The structure of the TATA element, partially unwound and severely bent on complexation, seems to be stabilized by CH/pi interactions; H2' of the deoxyribose moiety and the methyl group in the thymine nucleotide play the primary role.

A fluorescent indicator for detecting protein-protein interactions in vivo based on protein splicing

We describe a new method with general applicability for monitoring any protein-protein interaction in vivo. The principle is based on a protein splicing system, which involves a self-catalyzed excision of protein splicing elements, or inteins, from flanking polypeptide sequences, or exteins, leading to formation of a new protein in which the exteins are linked directly by a peptide bond. As the exteins, split N- and C-terminal halves of enhanced green fluorescent protein (EGFP) were used. When a single peptide consisting of an intein derived from Saccharomyces cerevisiae intervening the split EGFP was expressed in Escherichia coli, the two external regions of EGFP were ligated, thereby forming the EGFP corresponding fluorophore. Genetic alteration of the intein, which involved large deletion of the central region encoding 104 amino acids, was performed. In the expression of the residual N- and C-terminal intein fragments each fused to the split EGFP exteins, the splicing in trans did not proceed. However, upon coexpression of calmodulin and its target peptide M13, each connected to the N- and C-terminal inteins, fluorescence of EGFP was observed. These results demonstrate that interaction of calmodulin and M13 triggers the refolding of intein, which induces the protein splicing, thereby folding the ligated extein correctly for yielding the EGFP fluorophore. This method opens a new way not only to screen protein-protein interactions but also to visualize the interaction in vivo in transgenic animals.

A case of pyoderma gangrenosum on the stump of an amputated right leg

We present here a case of pyoderma gangrenosum (PG) on the stump of an amputated leg. The patient was a 69-year-old woman who had both of her legs amputated due to acute arterial occlusion. An ulcer first appeared nine years later, after which point it continued to fluctuate in size. Complications included regional blood flow disorder at the amputated stump, diabetes, and secondary infection. Despite various therapies, the ulcer exacerbated, and hypoproteinemia, increased CRP, and fever were confirmed. The patient was diagnosed as having PG based on her clinical symptoms and because the ulcer did not respond to various therapies. The ulcer improved significantly in response to administration of 40 mg/day of prednisolone, and complete epithelialization was later achieved. Given the presence of multiple complications, it was extremely difficult to confirm PG. Therefore, it is important for physicians to consider PG as one of the causes of intractable ulcers.

Evaluation of agonist selectivity for the NMDA receptor ion channel in bilayer lipid membranes based on integrated single-channel currents

A new method for evaluating chemical selectivity of agonists to activate the N-methyl-D-aspartate (NMDA) receptor was presented by using typical agonists NMDA, L-glutamate and (2S, 3R, 4S)-2-(carboxycyclopropyl)glycine (L-CCG-IV) and the mouse epsilon1/zeta1 NMDA receptor incorporated in bilayer lipid membranes (BLMs) as an illustrative example. The method was based on the magnitude of an agonist-induced integrated single-channel current corresponding to the number of total ions passed through the open channel. The very magnitudes of the integrated single-channel currents were compared with the different BLMs as a new measure of agonist selectivity. The epsilon1/zeta1 NMDA receptor was partially purified from Chinese hamster ovary (CHO) cells expressing the epsilon1/zeta1 NMDA receptor and incorporated in BLMs formed by the tip-dip method. The agonist-induced integrated single-channel currents were obtained at 50 microM agonist concentration, where the integrated current for NMDA was shown to reach its saturated value. The obtained integrated currents were found to be (4.5 +/- 0.55) x 10(-13) C/s for NMDA, (5.8 +/- 0.72) x 10(-13) C/s for L-glutamate and (6.6 +/- 0.61) x 10(-13) C/s for L-CCG-IV, respectively. These results suggest that the agonist selectivity in terms of the total ion flux through the single epsilon1/zeta1 NMDA receptor is in the order of L-CCG-IV approximately = L-glutamate > NMDA.

Analysis of the human sleep electroencephalogram by the correlation dimension

Sleep electroencephalograms (EEG) of healthy male subjects were analyzed by the correlation dimension. The mean correlation dimensions significantly decreased from stage 'awake' to stages 1, 2 and 3 and increased during rapid eye movement sleep. The mean correlation dimensions of the sleep EEG in the second half of the night were significantly higher than those in the first half of the night. These significant changes were also seen during sleep stage 2.

A screening method for antigen-specific IgE using mast cells based on intracellular calcium signaling

A simple screening method is presented for the measurement of antigen-specific IgEs in sera in which mast cells are used. This method is based on the intracellular calcium signal in mast cells induced by cross-linking the surface high-affinity Fc receptors (FcepsilonRIs) with IgEs and multivalent antigens. When a serum containing various antigen-specific IgEs is added to the mast cell suspension, various antigen-specific IgEs are captured by FcepsilonRIs on the cell surface. However, the required antigen-specific IgE can be specifically detected after the addition of the corresponding antigen. The resulting increase in intracellular calcium concentration ([Ca2+]i), monitored by Ca2+-fluorometry, was found to be an analytical measure for the screening of IgEs. Two kinds of rodent mast cells, cell-lined RBL2H3 cells and primary cultured BMMCs, were used as a representative model system of mast cells. A DNP hapten (DNP35-HSA) and ovalbumin (OVA) were chosen for illustrative antigens, and these antigen-specific IgEs (DNP-specific IgE, OVA-specific IgE) in the corresponding rodent sera were target antibodies. It was found that [Ca2+]i increased linearly with IgE concentrations ranging from 25 to 5000 ng/mL for DNP-specific IgE and from 5 to 50 ng/mL for OVA-specific IgE. For these dynamic ranges, optimum concentrations of antigens were found to be 10 ng/mL and 1 microg/mL for DNP35-HSA and OVA, respectively. It was concluded that by monitoring the increase of [Ca2+]i in mast cells, we could determine the antigen-specific IgEs. The present immunological assay based on the Ca2+ signal transduction in mast cells offers new possibilities for efficient screening of antigen-specific IgEs and the immunogenicity of IgE in sera.

Correlation dimension of the human sleep electroencephalogram

Sleep electroencephalogram (EEG) was analyzed by nonlinear analysis. Polysomnography of a healthy male subject was analyzed and the correlation dimension was calculated. The mean correlation dimensions decreased from stage 'awake' to stages 1, 2 and 3, and increased during rapid eye movement (REM) sleep. These results were also seen at every sleep cycle. During each sleep cycle the correlation dimensions decreased for slow wave sleep, then increased for REM sleep. The mean correlation dimension of the sleep EEG in the second half of the night was significantly higher than those in the first half of the night. A significant change was seen both during REM sleep as well as in sleep stage 2. Nonlinear analysis may be a useful method in the analysis of the entire sleep electroencephalogram.

An SPR-based screening method for agonist selectivity for insulin signaling pathways based on the binding of phosphotyrosine to its specific binding protein

A new screening method was developed that evaluates physiologically relevant chemical selectivity of agonists for insulin-signaling pathways. Phosphorylation (pY939) by an insulin-activated insulin receptor of a target peptide (Y939) derived from an insulin receptor substrate-1 (IRS-1) and its subsequent binding to another downstream target, the SH2 domain of PI-3 kinase (SH2N), were detected by surface plasmon resonance (SPR) spectrometry. This method is based on competitive binding of SH2N to pY939 either in a solution or on the gold surface of the SPR sensor chip. With increasing the concentration of pY939 in solution by the insulin-induced kinase reaction of insulin receptor, SH2N bound to pY939 in solution increases and the one on the sensor chip decreases, thereby causing a decrease in the SPR signal. The amount of thus-detected complex pY939-SH2N was found to depend on added insulin concentrations, confirming that the method utilized part of the sequential transduction mechanism of the insulin-signaling pathways. The kinase activity of insulin receptor-agonist complexes increased in the order of IGF-II < IGF-I < insulin, and neither vanadium ions nor thiazolidine-type medicines for NIDDM, troglitazone and pioglitazone, directly acted on both the kinase reaction of insulin receptor or the binding of pY939 to SH2N. The present approach will thus become a general method for screening agonists for one specific pathway in tyrosine phosphorylation of IRS-1 in insulin signaling, which is regulated by specific protein-protein interaction between a phosphorylated tyrosine in IRS-1 and its corresponding SH2 domain-containing protein such as PI-3 kinase, Grb2-Sos, or SHP2.

Metal ion selectivity for formation of the calmodulin-metal-target peptide ternary complex studied by surface plasmon resonance spectroscopy

Ion selectivities for Ca(2+) signaling pathways of 33 metal ions were examined based on the Ca(2+)-dependent on/off switching mechanism of calmodulin (CaM): Ca(2+) ion-induced selective binding of CaM-Ca(2+) ion complex to the target peptide was observed as an increase in surface plasmon resonance (SPR) signals. As the target peptide, M13 of 26-amino-acid residues derived from skeletal muscle myosin light-chain kinase was immobilized in the dextran matrix, over which sample solutions containing CaM and each metal ion were injected in a flow system. Large changes in SPR signals were also observed for Sr(2+), Ba(2+), Cd(2+), Pb(2+), Y(3+) and trivalent lanthanide ions, thereby indicating that not only Ca(2+) but also these metal ions induce the formation of CaM-M13-metal ion ternary complex. No SPR signal was, however, induced by Mg(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+) and all monovalent metal ions examined. The latter silent SPR signal indicates that these ions, even if they bind to CaM, are incapable of forming the CaM-M13-metal ion ternary complex. Comparing the obtained SPR results with ionic radii of those metal ions, it was found that all cations examined with ionic radii close to or greater than that of Ca(2+) induced the formation of the CaM-metal-M13 ternary complex, whereas those with smaller ionic radii were not effective, or much less so. Since these results are so consistent with earlier systematic data for the effects of various metal ions on the conformational changes of CaM, it is concluded that the present SPR analysis may be used for a simple screening and evaluating method for physiologically relevant metal ion selectivity for the Ca(2+) signaling via CaM based on CaM/peptide interactions.