Stable neural population dynamics in the regression subspace for continuous and categorical task parameters in monkeys

Neural population dynamics provide a key computational framework for understanding information processing in the sensory, cognitive, and motor functions of the brain. They systematically depict complex neural population activity, dominated by strong temporal dynamics as trajectory geometry in a low-dimensional neural space. However, neural population dynamics are poorly related to the conventional analytical framework of single-neuron activity, the rate-coding regime that analyzes firing-rate modulations using task parameters. To link the rate-coding and dynamical models, we developed a variant of state-space analysis in the regression subspace, which describes the temporal structures of neural modulations using continuous and categorical task parameters. In macaque monkeys, using two neural population datasets containing either of two standard task parameters, contiguous and categorical, we revealed that neural modulation structures are reliably captured by these task parameters in the regression subspace as trajectory geometry in a lower dimension. Furthermore, we combined the classical optimal-stimulus response analysis (usually used in rate-coding analysis) with the dynamical model and found that the most prominent modulation dynamics in the lower dimension were derived from these optimal responses. Using those analyses, we successfully extracted geometries for both task parameters that formed a straight geometry, suggesting that their functional relevance is characterized as a unidimensional feature in their neural modulation dynamics. Collectively, our approach bridges neural modulation in the rate-coding model and the dynamical system and provides researchers with a significant advantage in exploring the temporal structure of neural modulations for pre-existing datasets.Significant statementOur results differ from earlier studies and suggest that our state-space analysis in the regression subspace provides a mechanistic neural population structure for visual recognition of items when monkeys perceived continuous and categorical task parameters. The neural population dynamics obtained from different brain regions using different behavioral tasks were similar and may share some common underlying information processing in a neural network. Our approach provides a simple framework for incorporating the single-neuron approach into the dynamical model as a procedure for describing neural modulation dynamics in the brain. This analytic extension gives researchers a significant advantage in that all types of pre-existing data for single neuron activity are useful for easily exploring their dynamics in a low-dimensional neural modulation space.

Dynamic prospect theory: Two core decision theories coexist in the gambling behavior of monkeys and humans

Research in the multidisciplinary field of neuroeconomics has mainly been driven by two influential theories regarding human economic choice: prospect theory, which describes decision-making under risk, and reinforcement learning theory, which describes learning for decision-making. We hypothesized that these two distinct theories guide decision-making in a comprehensive manner. Here, we propose and test a decision-making theory under uncertainty that combines these highly influential theories. Collecting many gambling decisions from laboratory monkeys allowed for reliable testing of our model and revealed a systematic violation of prospect theory's assumption that probability weighting is static. Using the same experimental paradigm in humans, substantial similarities between these species were uncovered by various econometric analyses of our dynamic prospect theory model, which incorporates decision-by-decision learning dynamics of prediction errors into static prospect theory. Our model provides a unified theoretical framework for exploring a neurobiological model of economic choice in human and nonhuman primates.

Development of multiplex S-gene-targeted RT-PCR for rapid identification of SARS-CoV-2 variants by extended S-gene target failure

Background

Tracking SARS-CoV-2 variants of concern (VOC) by genomic sequencing is time-consuming. The rapid screening of VOCs is necessary for clinical laboratories. In this study, we developed a rapid screening method based on multiplex RT-PCR by extended S-gene target failure (eSGTF), a false negative result caused by S-gene mutations.

Methods

Three S-gene target (SGT) regions (SGT1, codons 65–72; SGT2, codons 152–159; and SGT3, codons 370–377) and an N-gene region (for internal control) were detected in single-tube. Four types of VOC (Alpha, Delta, Omicron BA.1, and Omicron BA.2) are classified by positive/negative patterns of 3 S-gene regions (eSGTF pattern).

Results

The eSGTF patterns of VOCs were as follows (SGT1, SGT2, SGT3; P, positive; N, negative): Alpha, NPP; Delta, PNP; Omicron BA.1, NPN pattern; and Omicron BA.2, PPN. As compared with the S-gene sequencing, eSGTF patterns were identical to the specific VOCs (concordance rate = 96.7%, N = 206/213). Seven samples with discordant results had a minor mutation in the probe binding region. The epidemics of VOCs estimated by eSGTF patterns were similar to those in Japan.

Conclusions

Multiplex RT-PCR and eSGTF patterns enable high-throughput screening of VOCs. It will be useful for the rapid determination of VOCs in clinical laboratories.

AB0431 THE EFFICACY OF BELIMUMAB (BEL) AS A SPARING CORTICOSTEROID AGENCY IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Background

Patients with SLE are recommended to continue the maintenance therapy with as less glucocorticoid as possible.1) However, tapering glucocorticoid often results in the recurrence of SLE. Current reports suggested that adding BEL to the standard therapy could lead to the reduction of glucocorticoid and the recurrence of SLE.2)

Objectives

The aim of this study is to evaluate the efficacy and the safety of BEL as co-treatment in the standard therapy of SLE.

Methods

Fourteen patients receiving the maintenance therapy of SLE were enrolled in this study. Dose of prednisolone (PSL), titer of anti-DNA antibody, WBC count, serum complement and SLE disease activity index (SLEDAI) were examined retrospectively at baseline and 24 months after administration of BEL.

Results

At the baseline, the mean age of patients was 48 years old, 11 patients were female, and the mean disease duration was 8.6 years. The mean dose of PSL was significantly reduced (meansease apre-administration of BEL:6.1±1.1 mg/day, 24 months after administration of BEL: 1.2 the baseline,p=0.001). Furthermore, six patients (43 %) could withdraw PSL without the flare of the disease. There were also statistical significance about SLEDAI between baseline and after treatment by BEL(2.1patients (43 %) cp=0.03) and the titer of anti-DNA antibody (6.8 withdraw PSL without tp=0.03). There were no statistical significant in WBC count (6177out the fla7e of the dp=0.24) and serum complement (C3 87significant in WBC count (61p=0.78, C4 20erum complement (C3 87signifp=0.54).

As for adverse event, bacterial pneumonia (n=1) and pulmonary cryptococcosis (n=1) was revealed.

Conclusion

Our study is suggested that co-treatment with BEL on standard SLE therapy was enable to prevent the flare of SLE and reduce the dose of PSL with statistical significance among the patients under the maintenance treatment of SLE. In almost half of the cases, patients could withdraw PSL without the flare.

References

[1]Ann Rheum Dis 2019; 78: 736-745.

[2]Ann Rheum Dis 2018; 77: 355-745.

Disclosure of Interests

None declared

Tracking SARS-CoV-2 variants by entire S-gene analysis using long-range RT-PCR and Sanger sequencing

INTRODUCTION

Genomic surveillance of the SARS-CoV-2 virus is important to assess transmissibility, disease severity, and vaccine effectiveness. The SARS-CoV-2 genome consists of approximately 30 kb single-stranded RNA that is too large to analyze the whole genome by Sanger sequencing. Thus, in this study, we performed Sanger sequencing following long-range RT-PCR of the entire SARS-CoV-2 S-gene and analyzed the mutational dynamics.

METHODS

The 4 kb region, including the S-gene, was amplified by two-step long-range RT-PCR. Then, the entire S-gene sequence was determined by Sanger sequencing. The amino acid mutations were identified as compared with the reference SARS-CoV-2 genome.

RESULTS

The S:D614G mutation was found in all samples. The R.1 variants were detected after January 2021. Alpha variants started to emerge in April 2021. Delta variants replaced Alpha in July 2021. Then, Omicron variants were detected after December 2021. These mutational dynamics in samples collected in the Chiba University Hospital were similar to those in Japan.

CONCLUSION

The emergence of variants of concern (VOC) has been reported by the entire S-gene analysis. As the VOCs have unique mutational patterns of the S-gene region, analysis of the entire S-gene will be useful for molecular surveillance of the SARS-CoV-2 in clinical laboratories.

AB0381 THE UTILITY OF HYDROXYCHLOROQUINE (HCQ) THERAPY FOR TWO YEARS AS A SPARING CORTICOSTEROID AGENCY IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Background:

Prednisolone (PSL) and HCQ are key drugs in the therapy of SLE. However, since PSL induce many harmful adverse events, PSL is preferred to be reduced especially in the maintenance therapy. The efficacy of HCQ for reducing the dose of PSL has not been revealed yet. So, we focused on the cessation of PSL under the treatment of HCQ with conventional SLE therapy.

Objectives:

The aim of this study is to evaluate the efficacy and the safety of HCQ as co-treatment in the standard therapy of SLE.

Methods:

SLE patients (n=30) under the maintenance therapy were enrolled in this study. Dose of PSL, titer of anti-DNA antibody, WBC count, serum complement and SLE disease activity index (SLEDAI) were examined retrospectively at 0 and 12 months after administration of HCQ.

Results:

Baseline patient-characteristics are as follows (mean±S.E); the age of patients was 54.4±3.2 years old, 21 patients (70%) were female, the disease duration was 108.5±25.2 months, SLEDAI was 4.0±0.9, the dose of PSL was 10.3±1.7 mg/day, the titer of anti-DNA antibody was 7.3±1.8 IU/ml, C3 was 85±4.3 mg/dl and C4 was 18±1.6 mg/dl.

The mean dose of PSL was reduced with statistically significance (pre-administration of HCQ:10.3±1.7 mg/day, 24 months after administration of HCQ:2.2±0.3 mg/day,p<0.0001). Furthermore, in this observation period, 6 patients could achieve the cessation of PSL.

SLEDAI was also significantly reduced (4.0±0.9 vs 1.0±0.3,p<0.01).

There was no statistical significance between before treatment by HCQ and after treatment in the titer of anti-DNA antibody (7.3±1.8 vs 2.8±1.6 IU/ml,p=0.06), WBC count (6208±4.9 vs 5096±3.3 /μl,p=0.06) and serum complement level (C3 85±4.3 mg/dl vs 89±4.0 mg/dl,p=0.52, C4 18±1.6 mg/dl vs 19±1.4 mg/dl,p=0.45). Relapse of SLE was clarified in only one patient.

As for adverse events (AEs), Severe bacterial infection (n=4), herpes zoster (n=1) and patellar tendon rupture (n=1) were revealed. All cases of the AEs were fully recovered.

Conclusion:

Our study suggested that co-treatment with HCQ on standard SLE therapy could be enable to prevent the flare of SLE and reduce the dose of PSL with statistical significance. In some cases, we could achieve the cessation of PSL treatment.

References:

None.

Disclosure of Interests:

None declared

Abstract P4-03-13: Obesity and breast cancer: The adipocyte-macrophage interaction as a mediator of metastasis

Obese individuals with breast cancer have a poorer prognosis and higher risk of metastatic disease vs. non-obese patients. Prior research has largely focused on defining the interactions between adipocytes and tumor cells, but other cell types may also play a role. Adipose tissue in obese individuals is characterized by a significant infiltration of macrophages. We have therefore investigated the adipocyte-macrophage interaction as a possible mechanism whereby obesity promotes breast cancer metastasis.

We performed co-culture with both human and murine cells to determine whether adipocytes influence the expression of metastasis-promoting signals in macrophages. For the human system we co-cultured primary breast adipocytes with THP-1 macrophages. For the murine system we co-cultured 3T3-L1 differentiated adipocytes with J774.1 macrophages. We then assayed the mRNA levels and protein expression of metastasis-promoting genes.

In both systems we found that co-culture with adipocytes increased the expression of Vascular Endothelial Growth Factor A (VEGF-A) in macrophages. In examining a potential mechanism, we also show that media collected from cultured adipocytes (adipocyte-conditioned media) activates the transcription factor Egr-1 in macrophages. Since Egr-1 is a known regulator of VEGF-A expression, this is a potential mechanism whereby VEGF-A transcription is up-regulated. Treatment of human macrophages with Interleukin-6, Leptin and Insulin induced VEGF-A levels to a similar degree as co-culture, identifying these as adipocyte-derived signals that can possibly mediate this effect.

In summary we have found that the interaction between adipocytes and macrophages leads to the up-regulation of the pro-angiogenic signal VEGF-A in macrophages. Therefore this represents a potential mechanism whereby obesity could promote breast cancer metastasis.

Citation Format: Connelly L, Yadav N, Barcikowski A, Imaizumi Y, Jacobs A. Obesity and breast cancer: The adipocyte-macrophage interaction as a mediator of metastasis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-03-13.

Preemptive Living Donor Kidney Transplantation and Kidney Function at the Initial Hospital Visit: A Single-Center Case-Control Study

BACKGROUND

Studies have revealed that patients who undergo preemptive kidney transplantation (PKT) have favorable prognoses compared with those who undergo kidney transplantation after the initiation of dialysis. The number of PKT cases performed worldwide has been increasing. The goal of this study was to determine the clinical characteristics of patients who may successfully receive PKT.

METHODS

A single-center, case-control study was conducted to determine the clinical factors that lead to referral for PKT.

RESULTS

Between April 1, 2009, and August 1, 2015, a total of 118 patients underwent living donor kidney transplantation. Thirty of these patients had not undergone dialysis before their initial visit to the study hospital. Of these, 20 received kidney transplantation before and after dialysis initiation, respectively (group PKT+, successful PKT; group PKT-, failed PKT). The baseline characteristics at the primary visit were compared between groups. The median duration from the first visit to the study institution to PKT was 5.6 ± 0.7 months. Serum creatinine (Cr) levels differed significantly between groups (PKT+ vs PKT-, 6.0 ± 0.3 mg/dL vs 7.5 ± 0.5 mg/dL; P = .03). The receiver-operating characteristic curves revealed that a serum Cr level >5.7 mg/dL at the initial visit to the unit was a cutoff point for predicting the success of PKT (area under the curve, 0.721; P = .02).

CONCLUSIONS

Our results indicate that PKT should be performed within ∼6 months of the initial visit to the transplant center. Serum Cr levels <5.7 mg/dL predict successful PKT.

Expression of myeloperoxidase in acute myeloid leukemia blasts mirrors the distinct DNA methylation pattern involving the downregulation of DNA methyltransferase DNMT3B

Myeloperoxidase (MPO) has been associated with both a myeloid lineage commitment and favorable prognosis in patients with acute myeloid leukemia (AML). DNA methyltransferase inhibitors (decitabine and zeburaline) induced MPO gene promoter demethylation and MPO gene transcription in AML cells with low MPO activity. Therefore, MPO gene transcription was directly and indirectly regulated by DNA methylation. A DNA methylation microarray subsequently revealed a distinct methylation pattern in 33 genes, including DNA methyltransferase 3 beta (DNMT3B), in CD34-positive cells obtained from AML patients with a high percentage of MPO-positive blasts. Based on the inverse relationship between the methylation status of DNMT3B and MPO, we found an inverse relationship between DNMT3B and MPO transcription levels in CD34-positive AML cells (P=0.0283). In addition, a distinct methylation pattern was observed in five genes related to myeloid differentiation or therapeutic sensitivity in CD34-positive cells from AML patients with a high percentage of MPO-positive blasts. Taken together, the results of the present study indicate that MPO may serve as an informative marker for identifying a distinct and crucial DNA methylation profile in CD34-positive AML cells.

Structural and affinity analyses of g-quadruplex DNA aptamers for camptothecin derivatives

We recently selected DNA aptamers that bind to camptothecin (CPT) and CPT derivatives from a 70-mer oligodeoxyribonucleotide (ODN) library using the Systematic Evolution of Ligands by EXponential enrichment (SELEX) method. The target-binding activity of the obtained 70-mer CPT-binding DNA aptamer, termed CA-70, which contains a 16-mer guanine (G)-core motif (G3TG3TG3T2G3) that forms a three-tiered G-quadruplex, was determined using fluorescence titration. In this study, truncated fragments of CA-70 that all have the G-core motif, CA-40, -20, -19, -18A, -18B, -17, and -16, were carefully analyzed. We found that CA-40 retained the target-binding activity, whereas CA-20, -19, and -18B exhibited little or no binding activities. Further, not only CA-18A but also the shorter length fragments CA-17 and -16 clearly retained the binding activity, indicating that tail strands of the G-quadruplex structure can significantly affect the target binding of G-quadruplex DNA aptamers. Further analyses using circular dichroism (CD) spectroscopy and fluorescence polarization (FP) assay were conducted to investigate the structure and affinity of G-quadruplex DNA aptamers.

Efficacy of base-modification on target binding of small molecule DNA aptamers

Nucleic acid aptamers are receptors of single-stranded oligonucleotides that specifically bind to their targets. Significant interest is currently focused on development of small molecule aptamers owing to their applications in biosensing, diagnostics, and therapeutics involving low molecular weight biomarkers and drugs. Despite great potential for their diverse applications, relatively few aptamers that bind to small molecules have been reported, and methodologies to enhance and broaden their functions by expanding chemical repertories have barely been examined. Here we describe construction of a modified DNA library that includes (E)-5-(2-(N-(2-(N(6)-adeninyl)ethyl))carbamylvinyl)-uracil bases and discovery of high-affinity camptothecin-binding DNA aptamers using a systematic evolution of ligands by the exponential enrichment method. Our results are the first to demonstrate the superior efficacy of base modification on affinity enhancement and the usefulness of unnatural nucleic acid libraries for development of small molecule aptamers.

Expression of podoplanin and classical cadherins in salivary gland epithelial cells of klotho-deficient mice

We have recently shown that salivary gland myoepithelial cells express podoplanin. Podoplanin indirectly binds the actin filament network which links classical cadherins. The study here is aimed to investigate the expression of podoplanin and cadherins on salivary gland myoepithelial cells and the changes in the aging cells using klotho-deficient (kl/kl) mice. The submandibular glands of kl/kl mouse lack granular ducts which express klotho in wild type mice, suggesting that klotho may be a gene responsible for granular duct development. Although aging resulted in growth suppression of myoepithelial cells because of the sparse distribution of the cells in kl/kl mouse salivary glands, the expression of podoplanin and E-cadherin was shown in aging myoepithelial cells. It is thought that podoplanin participates in the actin-E-cadherin networks which are maintained in aging myoepithelial cells. It was also shown that granular ducts were filled with P-cadherin, and that the P-cadherin amount was larger in the wild type mouse submandibular glands than in the sublingual and parotid glands of wild type mouse, and in the submandibular glands of kl/kl mouse. These findings suggest that the granular duct is an organ secreting soluble P-cadherin into the saliva.

Staged resection of large hypervascular vestibular schwannomas in young adults

Two young adults underwent resection of large hypervascular vestibular schwannomas (acoustic neuromas) via two-stage surgery. The first patient, a 27-year-old woman with hydrocephalus, had a large hypervascular vestibular tumor in the left cerebellopontine angle (CPA) supplied by the left anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA). The second patient, a 34-year-old woman, had a large AICA-supplied hypervascular vestibular tumor in the left CPA that displaced the brain stem significantly. At the initial stage, only the lateral aspect of the tumor was debulked due to excessive bleeding from the tumor bed. Angiography 1 or 2 months after the initial operation showed that the tumor was hypovascular. At the second stage, the remnant medial aspect of the tumor was relatively avascular and nonadherent to the brain stem. Without blood transfusion during the second stage, the tumor was removed totally in the first patient and subtotally in the second patient. Pathological examination revealed that dilatated blood vessels were prominently increased at the first surgery; however, at the second surgery, the number of blood vessels had decreased, showing necrosis and degeneration. Although there are no absolute indications for the staged resection of vestibular schwannomas, this procedure may represent one of the safest options for these difficult lesions in young adults.

Immunohistochemical examination for the distribution of podoplanin-expressing cells in developing mouse molar tooth germs

We recently reported the expression of podoplanin in the apical bud of adult mouse incisal tooth. This study was aimed to investigate the distribution of podoplanin-expressing cells in mouse tooth germs at several developing stages. At the bud stage podoplanin was expressed in oral mucous epithelia and in a tooth bud. At the cap stage podoplanin was expressed on inner and outer enamel epithelia but not in mesenchymal cells expressing the neural crest stem cell marker nestin. At the early bell stage nestin and podoplanin were expressed in cervical loop and odontoblasts. At the root formation stage both nestin and podoplanin were weakly expressed in odontoblasts generating radicular dentin. Podoplanin expression was also found in the Hertwig epithelial sheath. These results suggest that epithelial cells of developing tooth germ acquire the ability to express nestin, and that tooth germ epithelial cells maintain the ability to express podoplanin in oral mucous epithelia. The expression of podoplanin in odontoblasts was induced as tooth germ development advanced, but was suppressed with the completion of the primary dentin, suggesting that podoplanin may be involved in the cell growth of odontoblasts. Nestin may function as an intermediate filament that binds podoplanin in odontoblasts.

Autocrine and/or paracrine growth of aggressive ATLL cells caused by HGF and c-Met

Adult T-cell leukemia/lymphoma (ATLL) is a neoplasia characterized by the massive invasion of various organs by tumor cells. Previously, we found that expression of the gene for c-Met, a receptor tyrosine kinase for hepatocyte growth factor (HGF), was specific to the acute type among 41 patients with ATLL by microarray. First in the present study, we analyzed the survival of the patients in relation to expression of c-Met and HGF in ATLL cells. Expression of the former but not the latter was associated with poor prognosis. Then, we analyzed the growth of ATLL cells caused by HGF and c-Met. c-Met was expressed in 0/7 chronic ATLLs, 12/14 acute ATLLs, 1/1 IL-2-independent ATLL cell line and 1/7 IL-2-dependent ATLL cell lines as assessed by flow cytometry. HGF induced the proliferation of primary cells from most acute cases examined as well as the c-Met-positive KK1 cell line in contrast to c-Met-negative cells. HGF induced autophosphorylation of c-Met in c-Met-positive cells from an acute case and KK1 cells. The plasma level of HGF was elevated in acute as compared to chronic cases. The levels of HGF and/or IL-6 which induces the production of HGF by stromal cells, were elevated in the supernatant of short-term cultured cells from certain patients with acute or chronic disease. Finally, infiltrated ATLL cells and adjacent stromal cells in liver were shown to be positive for c-Met/HGF and HGF, respectively, in acute cases. Autocrine and/or paracrine growth caused by HGF and c-Met was suggested in aggressive ATLL cells secreting HGF and/or IL-6, respectively.

Expression of myeloperoxidase enhances the chemosensitivity of leukemia cells through the generation of reactive oxygen species and the nitration of protein

Myeloperoxidase (MPO), a pivotal lineage marker for acute myeloid leukemia (AML), has been also shown to have a prognostic value: a high percentage of MPO-positive blasts correlates to favorable prognosis. To understand the relationship between the expression of MPO in leukemia cells and the response to chemotherapeutic agents, we established MPO-expressing K562 leukemia cell lines and then treated them with cytosine arabinocide (AraC). Cells expressing wild-type MPO, but not mutant MPO that could not mature, died earlier of apoptosis than control K562 cells. Reactive oxygen species (ROS) were generated more in leukemia cells expressing MPO, and the generation was abrogated by MPO inhibitors or antioxidants. Tyrosine nitration of cellular protein also increased more in MPO-expressing K562 cells than control cells after treatment with AraC. In clinical samples, CD34-positive AML cells from high-MPO cases showed a tendency to be sensitive to AraC in the colony-formation assay, and the generation of ROS and the nitration of protein were observed only when the percentage of MPO-expressing cells was high. These data suggest that MPO enhances the chemosensitivity of AML through the generation of ROS and the nitration of proteins.

Expression and function of galectin-1 in adult neural stem cells

Neural stem cells (NSCs) in the adult mammalian brain proliferate and continuously produce new neurons. To date, there has been little research into the functions of lectins in adult NSCs. Recently, we reported that a lectin, galectin-1, is expressed on adult NSCs and promotes their proliferation through its carbohydrate-binding ability. This evidence raises the possibility that glycans play roles in the proliferation of adult NSCs.

Small number of HTLV-1-positive cells frequently remains during complete remission after allogeneic hematopoietic stem cell transplantation that are heterogeneous in origin among cases with adult T-cell leukemia/lymphoma

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) can provide long-term remission for patients with adult T-cell leukemia/lymphoma (ATLL) caused by human retrovirus, human T-lymphocyte virus (HTLV-1). To understand how HTLV-1-positive cells including ATLL cells were suppressed by allo-HSCT, we examined HTLV-1 provirus load and residual ATLL cells in peripheral blood of transplant recipients using PCR-based tests. We found that the copy number of HTLV-1 genome, called provirus, became very small in number after allo-HSCT; however, in most cases, provirus did not disappear even among long-term survivors. Tumor-specific PCR tests demonstrated that most of HTLV-1-positive cells that remained long after transplantation were not primary ATLL cells but donor-derived HTLV-1-positive cells. We also found a case having very low amount of residual disease in peripheral blood even long after transplantation. There was only one recipient in whom we failed to show the presence of HTLV-1 genome and antibody against HTLV-1 even with an extensive search, which strongly suggested the elimination of HTLV-1 after allo-HSCT. These results demonstrated that after allo-HSCT the small amount of residual HTLV-1-positive cells were heterogeneous in origin and that long-term disease control for ATLL could be obtained without the complete elimination of HTLV-1.

C-type natriuretic peptide activates a non-selective cation current in acutely isolated rat cardiac fibroblasts via natriuretic peptide C receptor-mediated signalling

In the heart, fibroblasts play an essential role in the deposition of the extracellular matrix and they also secrete a number of hormonal factors. Although natriuretic peptides, including C-type natriuretic peptide (CNP) and brain natriuretic peptide, have antifibrotic effects on cardiac fibroblasts, the effects of CNP on fibroblast electrophysiology have not been examined. In this study, acutely isolated ventricular fibroblasts from the adult rat were used to measure the effects of CNP (2 x 10(-8) M) under whole-cell voltage-clamp conditions. CNP, as well as the natriuretic peptide C receptor (NPR-C) agonist cANF (2 x 10(-8) M), significantly increased an outwardly rectifying non-selective cation current (NSCC). This current has a reversal potential near 0 mV. Activation of this NSCC by cANF was abolished by pre-treating fibroblasts with pertussis toxin, indicating the involvement of G(i) proteins. The cANF-activated NSCC was inhibited by the compounds Gd(3+), SKF 96365 and 2-aminoethoxydiphenyl borate. Quantitative RT-PCR analysis of mRNA from rat ventricular fibroblasts revealed the expression of several transient receptor potential (TRP) channel transcripts. Additional electrophysiological analysis showed that U73122, a phospholipase C antagonist, inhibited the cANF-activated NSCC. Furthermore, the effects of CNP and cANF were mimicked by the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG), independently of protein kinase C activity. These are defining characteristics of specific TRPC channels. More detailed molecular analysis confirmed the expression of full-length TRPC2, TRPC3 and TRPC5 transcripts. These data indicate that CNP, acting via the NPR-C receptor, activates a NSCC that is at least partially carried by TRPC channels in cardiac fibroblasts.

K+ currents regulate the resting membrane potential, proliferation, and contractile responses in ventricular fibroblasts and myofibroblasts

Despite the important roles played by ventricular fibroblasts and myofibroblasts in the formation and maintenance of the extracellular matrix, neither the ionic basis for membrane potential nor the effect of modulating membrane potential on function has been analyzed in detail. In this study, whole cell patch-clamp experiments were done using ventricular fibroblasts and myofibroblasts. Time- and voltage-dependent outward K+ currents were recorded at depolarized potentials, and an inwardly rectifying K+ (Kir) current was recorded near the resting membrane potential (RMP) and at more hyperpolarized potentials. The apparent reversal potential of Kir currents shifted to more positive potentials as the external K+ concentration ([K+]o) was raised, and this Kir current was blocked by 100–300 μM Ba2+. RT-PCR measurements showed that mRNA for Kir2.1 was expressed. Accordingly, we conclude that Kir current is a primary determinant of RMP in both fibroblasts and myofibroblasts. Changes in [K+]o influenced fibroblast membrane potential as well as proliferation and contractile functions. Recordings made with a voltage-sensitive dye, DiBAC3(4), showed that 1.5 mM [K+]o resulted in a hyperpolarization, whereas 20 mM [K+]o produced a depolarization. Low [K+]o (1.5 mM) enhanced myofibroblast number relative to control (5.4 mM [K+]o). In contrast, 20 mM [K+]o resulted in a significant reduction in myofibroblast number. In separate assays, 20 mM [K+]o significantly enhanced contraction of collagen I gels seeded with myofibroblasts compared with control mechanical activity in 5.4 mM [K+]o. In combination, these results show that ventricular fibroblasts and myofibroblasts express a variety of K+ channel α-subunits and demonstrate that Kir current can modulate RMP and alter essential physiological functions.

Sensitivity of adult T-cell leukaemia lymphoma cells to tumour necrosis factor-related apoptosis-inducing ligand

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis in many transformed cells, but not in normal cells, and hence TRAIL has recently emerged as a novel anti-cancer agent. Adult T-cell leukaemia lymphoma (ATLL) is a neoplasm of T-lymphocyte origin aetiologically associated with human T-lymphotropic virus type 1 (HTLV-I), and is resistant to standard anti-cancer therapy. We thus characterized the sensitivity of ATLL cells to TRAIL in this study. Although most primary ATLL cells and cell lines expressed TRAIL death receptors on their surface, they showed only restricted sensitivity to TRAIL. Among the 10 ATLL cell lines examined, one was sensitive, but two had insufficient death-receptor expression, two had an unknown resistant mechanism with abrogation of the death signal upstream of caspase-8, and the remaining five showed attenuation of the signal in both extrinsic and intrinsic pathways by X-linked inhibitor of apoptosis and Bcl-2/Bcl-xL respectively. Furthermore, the level of HTLV-I tax expression was significantly correlated to TRAIL resistance. Interestingly, ATLL cells themselves expressed TRAIL on the cell surface. Constitutive production of TRAIL may offer resistance, thus allowing the development of TRAIL-resistant ATLL cells. Consequently, the resistant mechanism in ATLL cells against TRAIL was assigned to multiple factors and was not explained by a definitive single agent.

A comparative study of zygotic twinning and triplet rates in eight countries, 1972-1999

Annual changes in twinning and triplet rates by zygosity were investigated in eight countries during the period 1972-1999 using vital statistics. The monozygotic (MZ) twinning rates in Denmark, Switzerland and the Slovak Republic remained more or less constant throughout this period, whereas those in England and Wales, the Federal Republic of Germany (Germany), the Netherlands, the Czech Republic and Japan increased significantly year by year. With the exception of the Slovak Republic, the dizygotic (DZ) twinning rate increased significantly year by year in each country. It was 2.9 times higher in Denmark and 1.5 times higher in Germany in 1999 than in 1972, and within the same range in the other countries. With two exceptions, the MZ triplet rates remained more or less constant in each country. On the other hand, the DZ and trizygotic (TZ) triplet rates increased significantly year by year in each country. The TZ rate increased 30-fold in Germany, 16.6-fold in Japan, 11.7-fold in Switzerland, 9.7-fold in the Czech Republic, 8.7-fold in the Netherlands, 6.4-fold in Denmark, 5.6-fold in England and Wales and 3.5-fold in the Slovak Republic. The higher DZ twinning rate and higher DZ and TZ triplet rates since 1983 have been attributed to the higher proportion of mothers being treated with ovulation-inducing hormones and in vitro fertilization (IVF) in Denmark, England and Wales, Germany, the Netherlands, Switzerland and Japan. After the introduction of fertility drugs and IVF, variations in the DZ twinning and triplet rates and the TZ triplet rates were not only due to biological factors, but also depended on the popularity of fertility drugs and IVF in each country. In the Slovak Republic, where human fertility might not be affected by some adverse environmental factors, the DZ:MZ ratio remained constant during the period 1972-1999.

Hippocampal heme oxigenase-1 in a murine cardiac arrest model

Heme oxygenase-1 (HO-1) is a member of the heat shock protein family (HSP-32). It responds to thermal stress in cultured glial cells. To our knowledge. nothing is known about the expression and response of the HO-1 in cerebral ischemia. Therefore, we show here the induction of HO-1 in the brain of mice after global cerebral ischemia. HO-1-like immunoreactivity was detected at 12, 24, and 48 hours after ischemia recirculation. The HO-1-like immunoreactive cells were observed in astrocytes in the hippocampal dentate gyrus and CA1. The peak level of HO-1-like immunoreactivity was found 48 hours after the recirculation. HO-1-like immunoreactivity was observed in GFAP-positive astrocytes by use of a double immunostaining method. These results provide direct evidence for the induction and localization of HO-1 immunoreactivity in vivo in a mouse cerebral ischemia. We suggest that HO-1, produced in astrocytes after ischemia-recirculation, may directly affect neurons to protect from cell death.

Possible involvement of interferon regulatory factor 4 (IRF4) in a clinical subtype of adult T-cell leukemia

Interferon regulatory factor (IRF) 4 is the lymphoid-specific transcription factor that is required for the proliferation of mitogen-activated T cells. IRF4 has been suggested to be involved in tumorigenesis because the overexpression of IRF4 caused the transformation of Rat-1 fibroblasts in vitro. Here, we show that IRF4 is constitutively expressed in adult T-cell leukemia (ATL)-derived cell lines, which were infected with human T-cell leukemia virus type-I, but hardly expressed the trans-activator protein, Tax. Similarly, constitutive expression of IRF4 was demonstrated in freshly isolated peripheral blood mononuclear cells (PBMC) from patients with either acute or chronic ATL. However, the high-level expression of IRF4 was specifically associated with acute ATL. With mitogen-activated PBMC from healthy donors, cell cycle analyses revealed that the induction of IRF4 occurred prior to cell cycle progression and the cells that had entered the cell cycle were predominantly IRF4-positive cells. In addition, ectopic expression of IRF4 in Rat-1 fibroblasts increased the S and G2 / M phase population significantly. Taken together, our results indicate that IRF4 is involved in the pathogenesis of ATL through its positive effect on the cell cycle, and that IRF4 can be used as a molecular marker of clinical subtype in ATL.

A novel function of sphingosine-1-phosphate to activate a non-selective cation channel in human endothelial cells

1. The Ca2+ entry pathway activated by sphingosine-1-phosphate (S1P) was examined in primary cultured vascular endothelial cells dispersed from human umbilical vein (HUVECs) by measuring intracellular Ca2+ concentration ([Ca2+]i), whole-cell membrane currents and single channel activity. 2. Application of S1P to HUVECs induced a slowly developing, sustained increase in [Ca2+]i. When Ca2+ was absent from the bathing solution, no S1P-induced changes in [Ca2+]i were observed. Tert-butylhydroquinone (BHQ), an inhibitor of Ca2+ pumps in endoplasmic reticulum, and histamine induced a transient elevation of [Ca2+]i in HUVECs. 3. Pretreatment of HUVECs with 100 ng x ml(-1) pertussis toxin (PTX) for 15 h almost abolished the S1P effect on [Ca2+]i and reduced the histamine effect to 40% of the control. The BHQ-induced elevation of [Ca2+]i was insensitive to PTX. 4. When whole-cell membrane currents were recorded using the amphotericin B-perforated-patch clamp technique while monitoring [Ca2+]i, application of S1P induced a tiny inward current (I(S1P)) which was followed by the elevation of [Ca2+]i. I(S1P) reversed at +20.0 +/- 2.7 mV under these experimental conditions. 5. When S1P was included in the pipette solution in the excised inside-out patch clamp configuration, single channel activity with a conductance of 17 pS was activated. This channel activity depended on the presence of intracellular GTP. 6. In summary, these results show that S1P has a novel effect in mammalian cardiovascular endothelium to activate a non-selective cation (NSC) channel in a GTP-dependent manner via a PTX-sensitive G-protein. This S1P-sensitive NSC channel acts as a Ca2+ entry pathway in endothelium.

Infant mortality rates in single, twin and triplet births, and influencing factors in Japan, 1995-98

The infant mortality rate (IMR) was analysed among single, twin and triplet births during the period from 1995 to 1998 using Japanese Vital Statistics. This study also investigated the effects of order of multiple births and of birthweight on the IMR. Proportions of neonatal deaths among total infant deaths were about 1/2 for singletons and 3/4 for both twins and triplets. Thus, to reduce the IMR, intensive care of multiple births is likely to be very important during the first month of life. The IMR was higher in males than females for both singletons and twins, but not in triplets. Relative risks of the IMR in multiples relative to singletons were 5-fold in twins and 12-fold in triplets. The IMR was higher in the second-born (18 per 1000 live births) than the first-born (16) twin and higher in the third-born (51) than the first-born (31) and the second-born (34) triplet. The higher risk in the second-born than the first-born twin may be related to delivery complications. The IMR decreased rapidly as birthweight increased in singletons, twins, and triplets. IMRs for < or =1500 g were 2.4 per 1000 live births in singletons, 5.9 in twins and 6.1 in triplets. The corresponding proportions of infant deaths were 75%, 33% and 10% respectively. The higher relative risks of multiple births are almost entirely the result of the lower birthweight distribution among twins and triplets. To reduce the IMR, birthweight is an important factor in twins, triplets and singletons. The overall early neonatal death rate decreased as gestational age rose in singletons, twins and triplets. For birthweights <1000 g, higher IMRs were related to gestational ages of <28 weeks.

[High throughput pharmacology for drug discovery]

High Throughput Screening (HTS) now plays an important role in the discovery of new lead compounds for novel therapeutic targets. The advantage of HTS over the conventional method, now termed as Low Throughput Screening (LTS), is that valuable compounds can be selected rapidly from a large number of samples with minimal human involvement. In spite of the growing awareness of HTS, the importance of the LTS in the drug discovery and development is still not changed. Advances in pharmacogenomics will also provide us many pharmacological targets, and thus increase the number of compounds that should be assayed by HTS and LTS. In this review, we will first describe the outline of HTS. We will next describe new approaches to develop and brush up the LTS: 1) screening method of drugs acting on ion channels by voltage-sensitive fluorescent dye, 2) functional assay method using reconstituted smooth muscle fiber, and 3) organ culture method as a useful model of vascular proliferative disease. These approaches, which work cooperatively with HTS, will contribute greatly to the development of new drugs.

C282Y and H63D mutations in the HFE gene have no effect on iron overload disorders in Japan

OBJECTIVE

The gene responsible for hereditary hemochromatosis close to the human leukocyte antigen A locus was previously identified and designated as HFE. This study was performed to evaluate the clinical significance of two mutations, C282Y and H63D of HFE, in Japanese patients with hepatic iron overload.

PATIENTS AND METHODS

We examined C282Y and H63D in 11 patients with primary hemochromatosis, 94 patients with chronic hepatitis C, 54 patients with miscellaneous liver diseases, and 151 healthy volunteers. The HFE gene region of DNA samples extracted from peripheral leukocytes was amplified by polymerase chain reaction. Restriction enzyme analysis was performed using SnaBI for C282Y and BclI for H63D. Direct sequence analysis was then performed when products suggested the presence of a mutation.

RESULTS

All the subjects studied were free from C282Y. None of the patients with hemochromatosis had H63D. One patient with chronic hepatitis C was homozygous, and 4 patients were heterozygous for H63D. Two patients with alcoholic liver disease were heterozygous for H63D. The prevalence of chromosomes with H63D was 6/188 (3.2%) in patients with chronic hepatitis C, 2/108 (1.9%) in patients with miscellaneous liver diseases, and 8/302 (2.6%) in healthy volunteers. These differences were not significant.

CONCLUSION

Our results suggested that neither C282Y nor H63D in HFE affect Japanese patients with hemochromatosis or chronic hepatitis C.

Estimated number of multiplets under 16 years using two sets of census data in Japan: 1990 and 1995

Data for sets of multiples under 16 years of age were obtained from the population censuses of Japan in 1990 and 1995. These numbered 147,188 twin pairs, 1410 sets of triplets, 59 sets of quadruplets, and 3 sets of quintuplets in 1990, with the corresponding numbers in 1995 being 141,354, 2,211, 136 and 12, respectively. The total number of sets of multiples was 148,660 in 1990 and 143,713 in 1995. Twinning, triplet, quadruplet and quintuplet rates were estimated for each age. Rates of monozygotic twins and triplets remained constant age by age up to 15 years, while the dizygotic twinning rate, and rates of di- and tri-zygotic triplets decreased over the same period. Quadruplet and quintuplet rates also decreased. The accuracy of estimating number of multiples from census data is discussed using data on vital statistics.

[3 cases of polymyalgia rheumatica (PMR), in which serum amyloid A was a useful index of the disease activity]

We encountered 3 cases of polymyalgia rheumatica (PMR), in which serum amyloid A (SAA) levels were correlated with clinical pictures after normalization of ESR and CRP levels. Therefore, it is suggested that SAA may be a useful index for evaluating the severity of intractable PMR. Case 1: The patient was a 75-year-old man. Although ESR and CRP levels were normalized after the administration of PSL (20 mg/day), myalgia persisted. When the dose of PSL was reduced, PMR recurred, which was relieved by administering 15 mg/day of PSL. However, myalgia recurred again when the dose of PSL was reduced thereafter. The elevated SAA level (33.0 micrograms/ml) was normalized by continuous administration of PSL without reducing the dose, resulting in the relief of myalgia. Case 2: The patient was a 65-year-old woman. The administration of PSL was initiated at a dose of 15 mg/day. Although myalgia was relieved, the symptom and elevated SAA levels persisted for approximately 3 months. Thereafter, PMR recurred, and SAA levels were markedly increased to 78.2 micrograms/ml. However, the symptom of PMR was eliminated by continuously administering PSL without reducing the dose. Although the dose of PSL was then reduced after the decrease in SAA levels, PMR did not recur. Case 3: The patient was an 88-year-old woman. Although the symptom of PMR was relieved by administering 15 mg/day of PSL, myalgia persisted. Since SAA levels were increased to 106 micrograms/ml, PSL was continuously administered without reducing the dose, resulting in the disappearance of the symptom and normalization of SAA levels approximately 3 months later. Although the dose of PSL was then reduced to 12.5 mg/day, PMR did not recur.

Local Ca(2+) transients and distribution of BK channels and ryanodine receptors in smooth muscle cells of guinea-pig vas deferens and urinary bladder

1. The relationship between Ca(2+) sparks spontaneously occurring at rest and local Ca(2+) transients elicited by depolarization was analysed using two-dimensional confocal Ca(2+) images of single smooth muscle cells isolated from guinea-pig vas deferens and urinary bladder. The current activation by these Ca(2+) events was also recorded simultaneously under whole-cell voltage clamp. 2. Spontaneous transient outward currents (STOCs) and Ca(2+) sparks were simultaneously detected at -40 mV in approximately 50 % of myocytes of either type. Ca(2+) sparks and corresponding STOCs occurred repetitively in several discrete sites in the subplasmalemmal area. Large conductance Ca(2+)-dependent K(+) (BK) channel density in the plasmalemma near the Ca(2+) spark sites generating STOCs was calculated to be 21 channels microm(-2). 3. When myocytes were depolarized from -60 to 0 mV, several local Ca(2+) transients were elicited within 20 ms in exactly the same peripheral sites where sparks occurred at rest. The local Ca(2+) transients often lasted over 300 ms and spread into other areas. The appearance of local Ca(2+) transients occurred synchronously with the activation of Ca(2+)-dependent K(+) current (I(K,Ca)). 4. Immunofluorescence staining of the BK channel alpha-subunit (BKalpha) revealed a spot-like pattern on the plasmalemma, in contrast to the uniform staining of voltage-dependent Ca(2+) channel alpha1C subunits along the plasmalemma. Ryanodine receptor (RyR) immunostaining also suggested punctate localization predominantly in the periphery. Double staining of BKalpha and RyRs revealed spot-like co-localization on/beneath the plasmalemma. 5. Using pipettes of relatively low resistance, inside-out patches that included both clustered BK channels at a density of over 20 channels microm(-2) and functional Ca(2+) storage sites were obtained at a low probability of approximately 5%. The averaged BK channel density was 3-4 channels microm(-2) in both types of myocyte. 6. These results support the idea that a limited number of discrete sarcoplasmic reticulum (SR) fragments in the subplasmalemmal area play key roles in the control of BK channel activity in two ways: (i) by generating Ca(2+) sparks at rest to activate STOCs and (ii) by generating Ca(2+) transients presumably triggered by sparks during an action potential to activate a large I(K,Ca) and also induce a contraction. BK channels and RyRs may co-localize densely at the junctional areas of plasmalemma and SR fragments, where Ca(2+) sparks occur to elicit STOCs.

Perinatal mortality in twins and factors influencing mortality in Japan, 1980--98

The perinatal mortality rate (PMR) in twins was analysed using Japanese vital statistics during the period 1980-98. There was a total of 1992 twin perinatal deaths. The PMR in twins significantly decreased from 91 per 1000 births in 1980 to 31 per 1000 in 1998. The PMR was higher in males than females, but the differences between the sexes decreased over time. It was significantly higher in the second-born than the first-born of the twins. The fetal death rate was 2.8 times higher in monozygotic than dizygotic twins. The PMR decreased to one-sixth for the maternal age group > or =40 years, one-fifth for <20 years, and between one-third and a half for 20--39 years during the period 1980--98. It was lowest for birthweights (BW) between 2500 g and 2999 g during the entire period; the PMR decreased with gestational age (GA) up to 38--39 weeks and increased thereafter. The effect of BW on the PMR was greater than that of GA except in the shorter GA group. The proportion of twin perinatal deaths with extremely low BW (<1000 g) increased from 50% in 1980 to 68% in 1998. Thus, the declining PMR was unlikely to be due to the improvement in BW in twins. It is likely that it is related to the improved medical management of twins during the perinatal period and the first week of life.

Usefulness and limitation of DiBAC4(3), a voltage-sensitive fluorescent dye, for the measurement of membrane potentials regulated by recombinant large conductance Ca2+-activated K+ channels in HEK293 cells

The usefulness of bis-(1,3-dibutylbarbituric acid)-trimethine oxonol (DiBAC4(3)), a voltage-sensitive fluorescent dye, for the measurement of membrane potentials (MPs) was evaluated in HEK293 cells, where alpha or alpha plus beta1 subunits of large conductance Ca2+-activated K+ (BK) channels were expressed (HEKBK alpha and HEKBK alphabeta). The fluorescent intensity of DiBAC4(3) was measured at various potentials under voltage-clamp for calibration to estimate the absolute MP semi-quantitatively. The resting MPs measured with DiBAC4(3) were roughly comparable to those recorded with a microelectrode; the MP in HEKBK alphabeta was 10-20 mV more negative than that in native HEK. In HEKBK alpha, the membrane hyperpolarization induced by 10 microM Evans blue, a BK channel opener, was detected with DiBAC4(3). NS-1619, another BK channel opener, induced gradual but substantial change in F/F(K) even in native HEK, while the BK channel opening effect was detected. Oscillatory membrane hyperpolarization was induced in HEKBK alphabeta by application of 10 microM acetylcholine via increase in intracellular Ca2+ concentration. The oscillatory hyperpolarization was, however, detected only as a slow hyperpolarization with DiBAC4(3). It can be concluded that relatively slow effects of BK channel modulators can be semi-quantitatively measured by use of DiBAC4(3) in HEKBK, while the limited temporal resolution and possible artifacts should be taken into account.

Ca2+-images of smooth muscle cells and endothelial cells in one confocal plane in femoral artery segments of the rat

Simultaneous recording of Ca2+-images in one confocal plane from vascular smooth muscle cells (SMCs) and endothelial cells (ECs) of an intact rat femoral artery segment was performed using indo-1 and a confocal microscope. During application of 10 microM acetylcholine (ACh), elevation and oscillation of intracellular Ca2+ concentration ([Ca2+]i) were observed in ECs but not in SMCs. Sequential conduction of Ca2+ oscillation from an EC to the neighboring ECs in one longitudinal direction was often observed in the presence of ACh. On the other hand, the activation of voltage-dependent Ca2+ channels by external 30 mM K+ resulted in the elevation of [Ca2+]i only in SMCs. When 10 microM ACh was added in the presence of 30 mM K+, it was observed in one confocal plane that [Ca2+]i in ECs and SMCs was almost simultaneously increased and decreased, respectively. The simultaneous recording method in this intact preparation will provide a line of valuable information about the interactions between SMCs and ECs, based on spatio-temporal analyses of absolute values of [Ca2+]i in individual cells.

Imaging of Ca2+ release by caffeine and 9-methyl-7-bromoeudistomin D and the associated activation of large conductance Ca2+-dependent K+ channels in urinary bladder smooth muscle cells of the guinea pig

Ca2+ release by caffeine and 9-methyl-7-bromoeudistomin D (MBED) and the concomitant activation of large conductance Ca2+-dependent K+ (BK) channels were analyzed using confocal Ca2+ imaging and whole cell voltage-clamp methods in guinea pig urinary bladder smooth muscle cells. Puff application of 3 or 10 mM caffeine for several seconds (2 - 5 s) elicited a large increase in intracellular Ca2+ concentration ([Ca2+]i) and induced a phasic outward current at a holding potential of -40 mV. The phasic outward current was the summation of spontaneous transient outward currents (STOCs) due to marked activation of BK channels and was followed by a short cessation of STOCs. Although the increase in superficial [Ca2+]i by caffeine was faster than that in global [Ca2+]i, the peak [Ca2+]i was identical in these areas. Puff application of 100 microM MBED also markedly enhanced STOCs for a few seconds. This response to MBED was not observed when stored Ca2+ was depleted by caffeine. The increase in [Ca2+]i by MBED occurred mainly in superficial areas. Longer application of 100 microM MBED for 2 min did not induce significant global [Ca2+]i increase but decreased the amount of Ca2+ release and cell shortening during the subsequent application of 10 mM caffeine. These results indicate that short application of MBED releases Ca2+ preferentially from superficial storage sites, presumably due to its slow approach to deeper sites. MBED may be a good pharmacological tool to manipulate selectively the superficial Ca2+ stores related to STOCs.

Conserved smooth muscle contractility and blood pressure increase in response to high-salt diet in mice lacking the beta3 subunit of the voltage-dependent calcium channel

Voltage-dependent calcium channels are crucially important for calcium influx and the following smooth muscle contraction. Beta subunits of these channels are known to modify calcium currents through pore-forming alpha subunits. Among the four reported independent beta subunits, the beta3 subunit is expressed in smooth muscle cells and thought to compose L-type calcium channels in the tissue. To determine the role of the beta3 subunit in the cardiovascular system, we have analyzed beta3-null mice. Electrophysiological examinations proved the existence of dihydropyridine (DHP)-sensitive. L-type calcium channels in the smooth muscle cells. Beta3-null mice show no apparent changes in smooth muscle contraction and sensitivity to DHP, and normal blood pressure when they are raised on a normal diet, but the 13 subunit deficient mice show elevated blood pressure in response to a high-salt diet, with significant reductions in plasma catecholamine concentrations. Our finding strongly suggests a close relationship between voltage-dependent channels and high blood pressure.

Molecular cloning and expression of the novel splice variants of K(+) channel-interacting protein 2

Two cDNAs encoding the splice variants of K(+) channel-interacting protein 2 (KChIP2) recently reported as human KChIP2 have been identified from rat, mouse, and human heart by RT-PCR. A longer variant, KChIP2L encodes a protein of 270 amino acids, which has a 50-amino-acid insertion in N-terminus in comparison with a shorter one, KChIP2S. Interestingly, both KChIP2S and KChIP2L (KChIP2S/L) but not the original KChIP2 were expressed in human heart and umbilical vein endothelial cells (HUVECs). KChIP2S transcripts but not KChIP2L were predominantly expressed in rat, mouse, and human heart and HUVECs, whereas both transcripts were expressed at low levels in other tissues such as brain, aorta, and kidney. Using chimeric proteins of green fluorescence protein (GFP) fused to the N-terminus of KChIP2S/L, the interactions between Kv4.3 and KChIP2S/L were analyzed in native and Kv4.3-expressed HEK293 cells. Specific localization of GFP-fused KChIP2S/L proteins on or near cell membrane was observed only in Kv4.3-expressed HEK293 cells.

Regional expression of the splice variants of Kv4.3 in rat brain and effects of C-terminus deletion on expressed K+ currents

In situ hybridization and RT-PCR analyses have revealed that, among three Kv4.3 splice variants (a, b, and c) with distinct C-terminal cytoplasmic domains, the mRNA for Kv4.3a is abundant in cerebral cortex, cerebellum, olfactory bulb, and medulla oblongata, whereas the mRNA for Kv4.3c is localized mainly to hippocampus. Three new distinct splice variants of Kv4.3 (Kv4.3d, e and f), which consist of 601, 635, and 628 amino acids, respectively, and have distinct C-terminal cytoplasmic domains, were isolated from rat brain by RT-PCR. Kv4.3b, d, e and f were expressed at much lower levels in brain. Mutagenesis which removed 149 amino acids in C-terminal domain of Kv4.3a significantly slowed its rate of recovery from inactivation as measured in heterologous expression in HEK293 cells. Surprisingly, however, neither the rate of inactivation nor voltage dependence of the activation and inactivation were changed.

Longitudinal gompertzian analysis of mortality from prostate cancer in Japan, 1955-1996

The purpose of this study was to determine whether prostate cancer mortality conforms to gompertzian analysis and, if so, what conclusions can be made regarding increasing prostate cancer mortality in Japan by the application of longitudinal gompertzian analysis. Data regarding 77,492 prostate cancer deaths reported during the period 1955 to 1996 were obtained from death certificate records in Japan. Age-adjusted prostate cancer mortality rates increased 6.4-fold during that period. The changing patterns in the mortality rate was explained by a constantly increasing number of elderly people. Age-specific mortality rate distributions between the ages of 50 and 84 years were highly gompertzian for each year during that period. The environmental factor for prostate cancer mortality increased 80% for that period. Gompertzian analysis suggests that rising mortality from prostate cancer may be related to rapidly changing lifestyles among Japanese. Intake of animal proteins was the most strongly correlated parameter considered with the mortality from prostate cancer.

The antiproliferative effect of mizoribine on rheumatoid synovial fibroblast mediated by induction of apoptosis

In order to investigate the mechanism of anti-rheumatic action of mizoribine (MZR), antiproliferative effect of MZR on synovial fibroblasts obtained from rheumatoid arthritis (RA) patients were examined. To examine the effect of MZR on DNA synthesis, total radioactivity of 3H-thymidine (3H-TdR) incorporated into the synovial fibroblasts was measured. Also quantification of DNA fragmentation of synovial fibroblasts in the cultured supernatant and cell associated Bcl-2 protein, which is suspected of interfering with apoptosis, were performed with enzyme-linked immunosorbent assay. MZR suppressed 3H-TdR incorporation into synovial fibroblasts in a dose dependent fashion. Significant inhibition (P < 0.01) was attained at the concentration of more than 1 microgram/ml of MZR. However, induction of DNA fragmentation which is characteristic of apoptosis, were observed at only 10 micrograms/ml of MZR over 72 h-incubation significantly. In terms of the Bcl-2 expression of synovial fibroblasts, up to 10 micrograms/ml of MZR has no effect on the expression of this protooncogene bcl-2 expression. These results suggest that MZR might suppress the growth of rheumatoid pannus by inhibition of synovial fibroblast proliferation partially through the induction of apoptosis of synovial fibroblast without modulating Bcl-2 expression.

Comparative study of the molecular and functional expression of L-type Ca2+ channels and large-conductance, Ca2+-activated K+ channels in rabbit aorta and vas deferens smooth muscle

The relationship between the density of ionic currents through major two channels, voltage-dependent L-type Ca2+ channels (L-type VDCC) and large-conductance, Ca2+-activated K+ channels (BKC), and the mRNA expression levels of alpha1C subunit of L-type VDCC (alpha1C) and alpha/beta subunits of BKC (alphaBK/betaBK) were compared in smooth muscle cells (SMC) of rabbit aorta and vas deferens using whole cell-voltage clamp and reverse transcription-polymerase chain reaction (RT-PCR) analyses. The density of the currents through VDCC (ICa) and BKC (IK,Ca) at +10 mV in aortic SMC was approximately one-seventh and one-sixth respectively of that in vas deferens. Whilst application of the Ca2+ channel agonist Bay K 8644 increased ICa by 75-90% in these SMC, the increase in IK,Ca was far greater in aorta than in vas deferens. The expression of the alpha1C transcript in vas deferens was approximately 3.5 times higher than that in aorta. In contrast, expression of alphaBK/betaBK was almost identical in both tissues, indicating the dissociation of IK,Ca density from the expression levels of BKC transcripts in aorta. The results were supported by Western blot and immunocytochemical analyses using subunit-specific antibodies. The lower Ca2+ influx through VDCC in aorta activates only a very limited fraction of BKC compared with that in vas deferens. The greater expression of BKC than of VDCC in aortic SMC contributes to a strong negative feed-back mechanism that minimizes membrane depolarization and acts as a safety margin to maintain low membrane excitability.