Patient-derived tumoroid models of pulmonary large-cell neuroendocrine carcinoma: a promising tool for personalized medicine and developing novel therapeutic strategies

Pulmonary large-cell neuroendocrine carcinoma (LCNEC), a disease with poor prognosis, is classified as pulmonary high-grade neuroendocrine carcinoma, along with small-cell lung cancer. However, given its infrequent occurrence, only a limited number of preclinical models have been established. Here, we established three LCNEC tumoroids for long-term culture. Whole-exome sequencing revealed that these tumoroids inherited genetic mutations from their parental tumors; two were classified as small-cell carcinoma (S-LCNEC) and one as non-small cell carcinoma (N-LCNEC). Xenografts from these tumoroids in immunodeficient mice mimicked the pathology of the parent LCNEC, and one reproduced the mixed-tissue types of combined LCNEC with a component of adenocarcinoma. Drug sensitivity tests using these LCNEC tumoroids enabled the evaluation of therapeutic agent efficacy. Based on translational research, we found that a CDK4/6 inhibitor might be effective for N-LCNEC and that Aurora A kinase inhibitors might be suitable for S-LCNEC or LCNEC with MYC amplification. These results highlight the value of preclinical tumoroid models in understanding the pathogenesis of rare cancers and developing treatments. LCNEC showed a high success rate in tumoroid establishment, indicating its potential application in personalized medicine.

Establishment and characterization of novel high mucus-producing lung tumoroids derived from a patient with pulmonary solid adenocarcinoma

Among mucus-producing lung cancers, invasive mucinous adenocarcinoma of the lung is a rare and unique subtype of pulmonary adenocarcinoma. Notably, mucus production may also be observed in the five subtypes of adenocarcinoma grouped under the higher-level diagnosis of Invasive Non-mucinous Adenocarcinomas (NMA). Overlapping pathologic features in mucus-producing tumors can cause diagnostic confusion with significant clinical consequences. In this study, we established lung tumoroids, PDT-LUAD#99, from a patient with NMA and mucus production. The tumoroids were derived from the malignant pleural effusion of a patient with lung cancer and have been successfully developed for long-term culture (> 11 months). Karyotyping by fluorescence in situ hybridization using an alpha-satellite probe showed that tumoroids harbored aneuploid karyotypes. Subcutaneous inoculation of PDT-LUAD#99 lung tumoroids into immunodeficient mice resulted in tumor formation, suggesting that the tumoroids were derived from cancer. Xenografts from PDT-LUAD#99 lung tumoroids reproduced the solid adenocarcinoma with mucin production that was observed in the patient's metastatic lymph nodes. Immunoblot analysis showed MUC5AC secretion into the culture supernatant of PDT-LUAD#99 lung tumoroids, which in contradistinction was barely detected in the culture supernatants of NCI-A549 and NCI-H2122 pulmonary adenocarcinoma cells known for their mucin-producing abilities. Here, we established a novel high-mucus-producing lung tumoroids from a solid adenocarcinoma. This preclinical model may be useful for elucidating the pathogenesis of mucus-producing lung cancer.

Targeting ROR1 in combination with osimertinib in EGFR mutant lung cancer cells

Lung cancer that exhibits epidermal growth factor receptor (EGFR) gene mutation is sensitive to EGFR-tyrosine kinase inhibitors (TKIs), such as osimertinib. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) may be involved in overcoming EGFR-TKI resistance. Growth inhibition, colony formation, apoptosis, and mRNA/protein levels in four osimertinib-sensitive and resistant cell lines transfected with small interfering RNA (siRNA) targeting ROR1 (siROR1) were evaluated. Cell growth and colony formation were suppressed and apoptosis was increased in all cell lines treated with siROR1. Although EGFR, AKT, and ERK phosphorylation were not suppressed in all cell lines, TGF-β2, AXL, CDH2, PARP1, PEG10, and TYMS mRNA expression levels were reduced. The combination of osimertinib with siROR1 was effective for the four cell lines, particularly in the two osimertinib-sensitive lines. In conclusion, targeting ROR1 in combination with osimertinib in EGFR mutant lung cancer may be a novel therapeutic option.

Clinical application of a lung cancer organoid (tumoroid) culture system

Despite high expectations for lung tumoroids, they have not been applied in the clinic due to the difficulty of their long-term culture. Here, however, using AO (airway organoid) media developed by the Clevers laboratory, we succeeded in generating 3 lung tumoroid lines for long-term culture (>13 months) from 41 lung cancer cases (primary or metastatic). Use of nutlin-3a was key to selecting lung tumoroids that harbor mutant p53 in order to eliminate normal lung epithelial organoids. Next-generation sequencing (NGS) analysis indicated that each lung tumoroid carried BRAFG469A, TPM3-ROS1 or EGFRL858R/RB1E737*, respectively. Targeted therapies using small molecule drugs (trametinib/erlotinib for BRAFG469A, crizotinib/entrectinib for TPM3-ROS1 and ABT-263/YM-155 for EGFRL858R/RB1E737*) significantly suppressed the growth of each lung tumoroid line. AO media was superior to 3 different media developed by other laboratories. Our experience indicates that long-term lung tumoroid culture is feasible, allowing us to identify NGS-based therapeutic targets and determine the responsiveness to corresponding small molecule drugs.

Targeting ROR1 in combination with pemetrexed in malignant mesothelioma cells

OBJECTIVE

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is overexpressed in a subset of malignant cells. However, it remains unknown whether ROR1 is targetable in malignant mesothelioma (MM). Therefore, in this study, we investigated the effects of ROR1 inhibition in mesothelioma cells.

MATERIALS AND METHODS

Growth inhibition, colony formation, apoptosis, and mRNA/protein levels using siRNA-transfected MM cells were evaluated. Cluster analysis using Gene Expression Omnibus repository of transcriptomic information was also performed.

RESULTS

Our results indicated that in three (H2052, H2452, and MESO-1) among four MM cell lines, ROR1 inhibition had anti-proliferative and apoptotic effects and suppressed the activation of AKT and STAT3. Although growth inhibition by siROR1 was minimal in another mesothelioma cell line (H28), colony formation was significantly suppressed. Microarray, quantitative polymerase chain reaction, and Western blot analyses showed that there were differences in the suppression of mRNA and proteins between H2452 and H28 cells transfected with siROR1 compared with those transfected with control siRNA. Cluster analysis further showed that MM tumors had relatively high ROR1 expression, although the cluster in them was different from that in MM cell lines. Thymidylate synthase, a target of pemetrexed, was downregulated in H2452 cells transfected with siROR1. Accordingly, a combination of pemetrexed with siROR1 was found to be effective in the three MM cell lines we studied.

CONCLUSION

Our findings may provide novel therapeutic insight into the treatment of advanced MM.

Abstract 3056: Development of an integrated CRISPR interference system targeting ΔNp63 to treat lung and esophageal squamous cell carcinoma

TP63 encodes two different transcripts that have opposite functions in transcriptional control. One transcript encodes TAp63 that is functionally similar to the tumor suppressor TP53. The other transcript, ΔNp63, lacks the transcription-activating domain of TAp63 and has been proposed to function as a potent oncogene in squamous cell carcinomas. In this study, we have developed an integrated CRISPR interference system to selectively suppress ΔNp63 and we have termed this system CRISPRiΔNp63. We engineered the CRISPRi using tandemized guide RNA expression cassettes to target the 50 to 100 bp downstream region of the transcription start site of ΔNp63 and we used inactivated Cas9 linked to the transcription repression module Krüppel-associated box repressor domain. The plasmid vector harboring CRISPRiΔNp63 repressed ΔNp63 transcriptional activity in lung and esophageal squamous cell carcinoma cells that express ΔNp63. Moreover, an all-in-one adenoviral vector containing tandemized gRNAs and the dCas9/KRAB expression cassette, Ad-CRISPRiΔNp63, suppressed ΔNp63 expression in squamous cell carcinomas cells. Ad-CRISPRiΔNp63 effectively decreased cell proliferation and colony formation and induced apoptosis in lung and esophageal squamous cell carcinoma cells in vitro. Moreover, the all-in-one vector significantly inhibited tumor growth in a lung squamous cell carcinoma xenograft mouse model in vivo. These results indicate that ΔNp63 suppression by CRISPRiΔNp63 might be an effective strategy for the treatment of lung and esophageal squamous cell carcinoma.

Citation Format: Masakazu Yoshida, Etsuko Yokota, Tetsushi Sakuma, Nagio Takigawa, Toshikazu Ushijima, Takashi Yamamoto, Yoshio Naomoto, Takuya Fukazawa, Tomoki Yamatsuji. Development of an integrated CRISPR interference system targeting ΔNp63 to treat lung and esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3056.

Abstract 1922: Targeted silencing of SOX2 by an artificial transcription factor showed antitumor effect in lung and esophageal squamous cell carcinoma

S0X2 is a transcription factor essential for early mammalian development and for the maintenance of stem cells. Recently, SOX2 was identified as a lineage specific oncogene, recurrently amplified and activated in lung and esophageal squamous cell carcinoma (SCC). In this study, we have developed a zinc finger-based artificial transcription factor (ATF) to selectively suppress SOX2 expression in cancer cells and termed the system ATF/SOX2. We engineered the ATF using six zinc finger arrays designed to target a 19 bp site in the SOX2 distal promoter and a KOX transcriptional repressor domain. A recombinant adenoviral vector Ad- ATF/SOX2 that expresses ATF/SOX2 suppressed SOX2 at the mRNA and protein levels in lung and esophageal SCC cells expressing SOX2. In these kinds of cells, Ad-ATF/SOX2 decreased cell proliferation and colony formation more effectively than the recombinant adenoviral vector Ad-shSOX2, which expresses SOX2 short hairpin RNA (shSOX2). Ad-ATF/SOX2 induced the cell cycle inhibitor CDKN1A more strongly than Ad-shSOX2. Importantly, the ATF did not suppress the cell viability of normal human cells. Moreover, Ad-ATF/SOX2 effectively inhibited tumor growth in a lung SCC xenograft mouse model. These results indicate that ATF/SOX2 would lead to the development of an effective molecular-targeted therapy for lung and esophageal SCC.

Citation Format: Etsuko Yokota, Tomoki Yamatsuji, Munenori Takaoka, Minoru Haisa, Nagio Takigawa, Noriko Miyake, Tomoko Ikeda, Tomoaki Mori, Ohno Serika, Takashi Sera, Takuya Fukazawa, Yoshio Naomoto. Targeted silencing of SOX2 by an artificial transcription factor showed antitumor effect in lung and esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1922.

Development of an integrated CRISPRi targeting ΔNp63 for treatment of squamous cell carcinoma

TP63 encodes TAp63, which is functionally similar to the tumor suppressor TP53, and ΔNp63, which lacks the transcription-activating domain of TAp63 and appears potently oncogenic in squamous cell carcinomas (SCCs). In this study, we developed an integrated CRISPR interference (CRISPRi) system to selectively suppress ΔNp63 (CRISPRiΔNp63). We engineered this CRISPRi using tandemized guide RNA expression cassettes that targeted the 50 to 100 bp downstream of the transcription start site of ΔNp63 in combination with inactivated Cas9 linked to the transcription repression module Krüppel-associated box repressor domain. The plasmid vector harboring CRISPRiΔNp63 repressed ΔNp63 transcription in lung and esophageal SCC cells. Likewise, Ad-CRISPRiΔNp63, an all-in-one adenoviral vector containing the tandemized gRNAs and dCas9/KRAB expression cassette suppressed ΔNp63 expression in SCC cells. Ad-CRISPRiΔNp63 also effectively decreased cell proliferation and colony formation and induced apoptosis in lung and esophageal SCC cells in vitro and significantly inhibited tumor growth in a mouse lung SCC xenograft model in vivo. These results indicate that ΔNp63 suppression using CRISPRiΔNp63 may be an effective strategy for treating lung and esophageal SCC.

Targeted silencing of SOX2 by an artificial transcription factor showed antitumor effect in lung and esophageal squamous cell carcinoma

SOX2 is a transcription factor essential for early mammalian development and for the maintenance of stem cells. Recently, SOX2 was identified as a lineage specific oncogene, recurrently amplified and activated in lung and esophageal squamous cell carcinoma (SCC). In this study, we have developed a zinc finger-based artificial transcription factor (ATF) to selectively suppress SOX2 expression in cancer cells and termed the system ATF/SOX2. We engineered the ATF using six zinc finger arrays designed to target a 19 bp site in the SOX2 distal promoter and a KOX transcriptional repressor domain. A recombinant adenoviral vector Ad-ATF/SOX2 that expresses ATF/SOX2 suppressed SOX2 at the mRNA and protein levels in lung and esophageal SCC cells expressing SOX2. In these kinds of cells, Ad-ATF/SOX2 decreased cell proliferation and colony formation more effectively than the recombinant adenoviral vector Ad-shSOX2, which expresses SOX2 short hairpin RNA (shSOX2). Ad-ATF/SOX2 induced the cell cycle inhibitor CDKN1A more strongly than Ad-shSOX2. Importantly, the ATF did not suppress the cell viability of normal human cells. Moreover, Ad-ATF/SOX2 effectively inhibited tumor growth in a lung SCC xenograft mouse model. These results indicate that ATF/SOX2 would lead to the development of an effective molecular-targeted therapy for lung and esophageal SCC.

Abstract 2085: Development of a novel targeted therapy for malignant mesothelioma carcinoma by a midkine inhibitor

Malignant pleural mesothelioma is an aggressive tumor of mesenchymal origin and is increasing worldwide as a result of widespread exposure to asbestos. The median survival of patients with mesothelioma from time of diagnosis ranges between 1 and 2 years. The mortality is expected to increase, at least until 2020, which is mainly due to the long latency (30-50 years) of the disease. Despite considerable advances in the understanding of its pathogenesis and etiology, malignant mesothelioma remains largely unresponsive to standard modalities of cancer therapy. Thus, there is an urgent need for new therapeutic options for mesothelioma.Midkine (MDK) is a heparin-binding growth factor that is highly expressed in many malignant tumors, including lung cancers. We have previously reported that a MDK inhibitor, iMDK, suppresses non-small cell lung cancer expressing MDK without harming normal cells. Importantly, iMDK inhibits the PI3 kinase / Akt pathway and induces apoptosis in MDK expressing non-small cell lung cancer cells. In the present study, we have investigated the antitumor effect of iMDK against malignant mesothelioma both in vitro and in vivo. 48 hours after treatment, iMDK dose-dependently inhibited cell growth of MDK expressing malignant mesothelioma cells. iMDK also suppressed colony formation of MSTO-211H mesothelioma cells. TUNEL positive cells were significantly increased in MSTO-211H cells 48 hours after iMDK treatment in a dose-dependent manner, confirming the induction of apoptosis in mesothelioma cells by iMDK. Combination treatment of iMDK and Bcl-2 inhibitor ABT-263 is more effective than each drug alone in MSTO-211H mesothelioma cells. Moreover, systemic administration of iMDK significantly inhibited tumor growth in a mesothelioma xenograft tumor in vivo. Inhibition of MDK with iMDK provides a potential therapeutic approach for the treatment of malignant mesothelioma that is driven by MDK.

Citation Format: Takuya Fukazawa, Yuitaka Maeda, Tomoki Yamatsuji, Munenori Takaoka, Masakazu Yoshida, Naomasa Ishida, Miki Iwai, Etsuko Yokota, Takuro Yukawa, Minoru Haisa, Noriko Miyake, Tomoko Ikeda, Nagio Takigawa, Jeffery Whitsett, Yoshio Naomoto. Development of a novel targeted therapy for malignant mesothelioma carcinoma by a midkine inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2085. doi:10.1158/1538-7445.AM2017-2085

Abstract 2019: SOX2 silencing upregulates CDKN1A and suppresses growth of lung squamous cell carcinoma

SOX2 is a master pluripotency controller that was recently identified as a novel major oncogene, recurrently amplified and activated in lung squamous cell carcinoma (lung SCC). Then, transcriptional downstream targets of SOX2 have been actively investigated; however, such targets are often cell line specific. Here, in order to identify highly consensus SOX2 downstream genes in lung SCC cells, we used RNA-seq data from 178 lung SCC specimens (containing tumor and tumor-associated cells) and analyzed the correlation between SOX2 and previously-reported SOX2-controlled genes in lung SCC. In addition, we used another RNA-seq dataset from 105 non-small cell lung cancer cell lines (NSCLC; including lung SCC cells) and again analyzed the correlation between SOX2 and the reported SOX2-controlled genes in the NSCLC cell lines (no tumor-associated cells). We combined the two analyses and identified genes commonly correlated with SOX2 in both datasets. Among the 99 genes reported as SOX2 downstream and/or correlated genes, we found 4 negatively-correlated (e.g., CDKN1A) and 11 positively-correlated genes with SOX2. We used biological studies to demonstrate that CDKN1A was suppressed by SOX2 in lung SCC cells. G1 cell cycle arrest induced by SOX2 siRNA was rescued by CDKN1A siRNA. These results indicate that the tumorigenic effect of SOX2 in lung SCC cells is mediated in part by suppression of CDKN1A.

Citation Format: Takuya Fukazawa, Tomokoki Yamatsuji, Munenori Takaoka, Etsuko Yokota, Minoru Haisa, Naomasa Ishida, Masakazu Yoshida, Noriko Miyake, Nagio Takigawa, Yutaka Maeda, Yoshio Naomoto. SOX2 silencing upregulates CDKN1A and suppresses growth of lung squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2019.

Tobacco karyotyping by accurate centromere identification and novel repetitive DNA localization

Tobacco (Nicotiana tabacum) is an amphidiploid species (2n = 4x = 48, genome constitution SSTT) derived from a natural hybrid between Nicotiana sylvestris (2n = 2x = 24, SS) and Nicotiana tomentosiformis (2n = 2x = 24, TT). Genomic in situ hybridization (GISH), using the genomic DNA from these ancestral species as probes, revealed the chromosomal origins (S or T) and the occurrence of intergenomic translocations in N. tabacum. Fluorescence in situ hybridization (FISH) was also used to distinguish between chromosomes. However, the use of repetitive DNA sequences as probes for FISH analysis is limited by an inability to identify all chromosomes. In addition to this limitation, the occurrence of chromosomal tertiary constrictions can easily lead to the misclassification of chromosomes. To overcome these issues, immunostaining with anti-N. tabacum centromere-specific histone H3 antibody was carried out to determine the centromere position of each chromosome, followed by FISH analysis with ten distinct repetitive DNA probes. This approach allowed us to identify 22 of the 24 chromosome pairs in N. tabacum and revealed novel intergenomic chromosome rearrangements and B-chromosome-like minichromosomes. Hence, the combination of immunostaining with FISH and GISH is critical to accurately karyotype tobacco.

Generation of an artificial ring chromosome in Arabidopsis by Cre/LoxP-mediated recombination

A eukaryotic chromosome consists of a centromere, two telomeres and a number of replication origins, and 'artificial chromosomes' may be created in yeast and mammals when these three elements are artificially joined and introduced into cells. Plant artificial chromosomes (PACs) have been suggested as new vectors for the development of new crops and as tools for basic research on chromosomes. However, indisputable PAC formation has not yet been confirmed. Here, we present a method for generating PACs in the model plant Arabidopsis thaliana using the Cre/LoxP and Activator/Dissociation element systems. The successfully generated PAC, designated AtARC1 (A. thaliana artificial ring chromosome 1), originated from a centromeric edge of the long arm of chromosome 2, but its size (2.85 Mb) is much smaller than that of the original chromosome (26.3 Mb). Although AtARC1 contains only a short centromere domain consisting of 180 bp repeats approximately 250 kb in length, compared with the 3 Mb domain on the original chromosome 2, centromere-specific histone H3 (HTR12) was detected on the centromeric region. This result supported the observed stability of the PAC during mitosis in the absence of selection, and transmission of the PAC to the next generation through meiosis. Because AtARC1 contains a unique LoxP site driven by the CaMV 35S promoter, it is possible to introduce a selectable marker and desired transgenes into AtARC1 at the LoxP site using Cre recombinase. Therefore, AtARC1 meets the criteria for a PAC and is a promising vector.

[S-1-based chemotherapy for unresectable advanced gastric cancer of the elderly or patients with renal dysfunction]

OBJECTIVE

S-1 based therapy is a valued standard chemotherapy regimen for unresectable gastric cancer in Japan. S-1/ CDDP therapy has been highly effective, especially for patients under 75 years old who have good organ function. However, it is the elderly and/or patients with renal dysfunction who make up the majority of the candidates for chemotherapy in general hospitals. These factors make it difficult to apply the results of RCTs to chemotherapy regimens.

AIM AND METHODS

To investigate clinical outcomes, the medical records of patients who had received S-1 based chemotherapy for gastric cancer at our hospital from January 2002 to September 2009 were retrospectively reviewed.

RESULTS

A total of 78 patients were evaluated for analyses. Among the patients, 23(29%)were the elderly, 8(10%)had renal dysfunction, and 27(35%)were either the elderly or those who had renal dysfunction. S-1/CDDP therapy was provided for 63% of the patients. Regarding the outcomes from therapy, RR was 44%, mPFS was 5. 4 months, and MST was 10. 6 months. Regarding survival benefit for OS, the elderly, the intestinal type, and therapy with S-1 alone were considered to be good factors in multi-variant analysis, but no significant differences were confirmed.

CONCLUSION

In general practice, the elderly and/or patients with renal dysfunction account for 35%, and S-1-based chemotherapy has been proven to be very effective. However, additional effects of CDDP were not shown in this study.

Clathrin is involved in organization of mitotic spindle and phragmoplast as well as in endocytosis in tobacco cell cultures

We previously identified a 175 kDa polypeptide in Lilium longiflorum germinating pollen using a monoclonal antibody raised against myosin II heavy chain from Physarum polycephalum. In the present study, the equivalent polypeptide was also found in cultured tobacco BY-2 cells. Analysis of the amino acid sequences revealed that the 175 kDa polypeptide is clathrin heavy chain and not myosin heavy chain. After staining of BY-2 cells, punctate clathrin signals were distributed throughout the cytoplasm at interphase. During mitosis and cytokinesis, clathrin began to accumulate in the spindle and the phragmoplast and then was intensely concentrated in the cell plate. Expression of the C-terminal region of clathrin heavy chain, in which light chain binding and trimerization domains reside, induced the suppression of endocytosis and the formation of an aberrant spindle, phragmoplast, and cell plate, the likely cause of the observed multinucleate cells. These data strongly suggest that clathrin is intimately involved in the formation of the spindle and phragmoplast, as well as in endocytosis.

Possible association of actin filaments with chloroplasts of spinach mesophyll cells in vivo and in vitro

In palisade mesophyll cells of spinach (Spinacia oleracea L.) kept under low-intensity white light, chloroplasts were apparently immobile and seemed to be surrounded by fine bundles of actin filaments. High-intensity blue light induced actin-dependent chloroplast movement concomitant with the appearance of a couple of long, straight bundles of actin filaments in each cell, whereas high-intensity red light was essentially ineffective in inducing these responses. The actin organization observed under low-intensity white light has been postulated to function in anchoring chloroplasts at proper intracellular positions through direct interaction with the chloroplasts. Intact chloroplasts, which retained their outer envelopes, were isolated after homogenization of leaves and Percoll centrifugation. No endogenous actin was detected by immunoblotting in the final intact-chloroplast fraction prepared from the leaves kept under low-intensity white light or in darkness. In cosedimentation assays with exogenously added skeletal muscle filamentous actin, however, actin was detected in the intact-chloroplast fraction precipitated after low-speed centrifugation. The association of actin with chloroplasts was apparently dependent on incubation time and chloroplast density. After partial disruption of the outer envelope of isolated chloroplasts by treatment with trypsin, actin was no longer coprecipitated. The results suggest that chloroplasts in spinach leaves can directly interact with actin, and that this interaction may be involved in the regulation of intracellular positioning of chloroplasts.

The origin, meiotic behavior, and transmission of a novel minichromosome in Arabidopsis thaliana

A plant carrying a small extra chromosome was found in Landsberg erecta ecotype of Arabidopsis thaliana. Fluorescence in situ hybridization revealed that this minichromosome was derived from the short arm of chromosome 4. The size of this "mini4S" chromosome was estimated to be approximately 7.5 Mb on the basis of previously reported data and the amount of the centromeric major satellite (180-bp family) present, which was determined to be about 1 Mb, or about one third of that in the normal chromosome 4. No pairing between mini4S and its original chromosome 4 was observed at pachytene and metaphase I stages. The transmission of mini4S through pollen was limited, but about 30% of selfed progeny carried the mini4S chromosomes. The transmission rates considerably increased when the mini4S chromosomes were transferred to plants with a Columbia background by successive backcrosses. This suggests that the stability of the minichromosomes is controlled genetically by factors that can vary between ecotypes.

Investigation of the effect of the c-kit inhibitor Glivec on isolated guinea-pig detrusor preparations

In order to assess the possible role of the c-kit positive cells in the bladder, the effects of c-kit tyrosine kinase inhibitor, Glivec, on spontaneous excitation and ion channel activity in detrusor smooth muscles of the guinea-pig bladder were investigated using intracellular microelectrodes, isometric muscle tension recordings and patch clamp techniques. Glivec (10 microM) converted action potential bursts into continuous firing without affecting their shape but at 50 microM abolished spontaneous action potentials. It had little effect on inward and outward currents at <10 microM, but inhibited them at >50 microM. Glivec decreased the amplitude of spontaneous contractions dose dependently. These results suggest that c-kit positive cells may play a role in modulating spontaneous electrical and mechanical activities. Drugs inhibiting the c-kit receptor may provide a new approach for treating the overactive bladder.

Possible involvement of energy metabolism in the change of cytoplasm organization induced by a protein phosphatase inhibitor, calyculin A, in root hair cells of Limnobium stoloniferum

In root hair cells of Limnobium stoloniferum, transvacuolar strands disperse and cytoplasmic spherical bodies (CSBs) emerge upon treatment with a protein phosphatase inhibitor, calyculin A (CA), whose effects were previously shown to be canceled by simultaneous treatment of the cells with a nonselective protein kinase inhibitor, K-252a. CSB formation is also suppressed by latrunculin B (LB) or cytochalasin D, actin filament depolymerization drugs, or 2,3-butanedione monoxime, an inhibitor of myosin activity. To confirm the involvement of myosin activity in CSB formation induced by CA, we examined the effect of an inhibitor of energy metabolism, NaN3, on CSB formation in root hair cells pretreated simultaneously with CA and LB. In the presence of CA-LB, CSB formation was suppressed due to the depolymerization of actin filaments. When these drugs were removed, the actin filaments recovered and CSBs emerged even in the presence of K-252a. These results indicated that the phosphorylation level in the cells is elevated during the CA-LB treatment and that a phosphorylation level sufficient for the CSB formation was sustained even after CA removal. On the other hand, CSB formation after simultaneous treatment with CA and LB was significantly suppressed in the presence of NaN3. In such cells, actin filament bundles recovered, although their organization was random. The present and previous results suggested that myosin activity is necessary for CSB formation induced by CA, and that myosin regulated by phosphorylation-dephosphorylation is implicated in the organization of the actin cytoskeleton in root hair cells.

Direct observation of processive movement by individual myosin V molecules

Myosin V is an unconventional myosin thought to move processively along actin filaments. To have hard evidence for the high processivity, we sought to observe directly the movement by individual native chick brain myosin V (BMV) molecules with fluorescent calmodulin. Single BMV molecules did exhibit highly processive movement along actin filaments fixed to a coverslip. BMV continued to move up to the barbed end of its actin track, and did not readily detach from action. The barbed end, therefore, got brighter with time, because of a constant stream of BMV traffic. The maximum speed of the processive movement was 1 microm/s, and the maximum actin-activated ATPase rate was 2.4 s(-1). These values apparently imply that BMV travels a great distance, 400 nm, per an ATPase cycle.

Calcium-calmodulin suppresses the filamentous actin-binding activity of a 135-kilodalton actin-bundling protein isolated from lily pollen tubes

We have isolated a 135-kD actin-bundling protein (P-135-ABP) from lily (Lilium longiflorum) pollen tubes and have shown that this protein is responsible for bundling actin filaments in lily pollen tubes (E. Yokota, K. Takahara, T. Shimmen [1998] Plant Physiol 116: 1421-1429). However, only a few thin actin-filament bundles are present in random orientation in the tip region of pollen tubes, where high concentrations of Ca(2+) have also been found. To elucidate the molecular mechanism for the temporal and spatial regulation of actin-filament organization in the tip region of pollen tubes, we explored the possible presence of factors modulating the filamentous actin (F-actin)-binding activity of P-135-ABP. The F-actin-binding activity of P-135-ABP in vitro was appreciably reduced by Ca(2+) and calmodulin (CaM), although neither Ca(2+) alone nor CaM in the presence of low concentrations of Ca(2+) affects the activity of P-135-ABP. A micromolar order of Ca(2+) and CaM were needed to induce the inhibition of the binding activity of P-135-ABP to F-actin. An antagonist for CaM, W-7, cancelled this inhibition. W-5 also alleviated the inhibition effect of Ca(2+)-CaM, however, more weakly than W-7. These results suggest the specific interaction of P-135-ABP with Ca(2+)-CaM. In the presence of both Ca(2+) and CaM, P-135-ABP organized F-actin into thin bundles, instead of the thick bundles observed in the absence of CaM. These results suggest that the inhibition of the P-135-ABP activity by Ca(2+)-CaM is an important regulatory mechanism for organizing actin filaments in the tip region of lily pollen tubes.

The role of plant villin in the organization of the actin cytoskeleton, cytoplasmic streaming and the architecture of the transvacuolar strand in root hair cells of Hydrocharis

In many types of plant cell, bundles of actin filaments (AFs) are generally involved in cytoplasmic streaming and the organization of transvacuolar strands. Actin cross-linking proteins are believed to arrange AFs into the bundles. In root hair cells of Hydrocharis dubia (Blume) Baker, a 135-kDa polypeptide cross-reacted with an antiserum against a 135-kDa actin-bundling protein (135-ABP), a villin homologue, isolated from lily pollen tubes. Immunofluorescence microscopy revealed that the 135-kDa polypeptide co-localized with AF bundles in the transvacuolar strand and in the sub-cortical region of the cells. Microinjection of antiserum against 135-ABP into living root hair cells induced the disappearance of the transvacuolar strand. Concomitantly, thick AF bundles in the transvacuolar strand dispersed into thin bundles. In the root hair cells, AFs showed uniform polarity in the bundles, which is consistent with the in-vitro activity of 135-ABP. These results suggest that villin is a factor responsible for bundling AFs in root hair cells as well as in pollen tubes, and that it plays a key role in determining the direction of cytoplasmic streaming in these cells.

Regulation of cytoplasmic pH under extreme acid conditions in suspension cultured cells of Catharanthus roseus: a possible role of inorganic phosphate

Changes in cytoplasmic pH of suspension-cultured cells of Catharanthus roseus under extreme acid conditions were measured with the pH-dependent fluorescence dye; 2',7'-bis-(2-carboxyethyl)-5 (and-6) carboxyfluorescein (-acetoxymethylester) (BCECF). When cells were treated with 1 mM HCl (pH 3 solution), the cytoplasmic pH first decreased then returned to the original level. Treatment with 10 mM HCl (pH 2 solution) acidified the cytoplasm to a greater extent, and the acidification continued at a constant level throughout the measurement. Treatment with a pH 2 solution resulted in a gradual decrease of the malate content, indicating the operation of biochemical pH regulation mechanism. The pH 2 treatment also caused a sudden decrease of the intracellular level of Pi. The cellular content of total phosphorus did not change during the acidification. The Pi was converted to the organic phosphate form. The ATP level was not increased by the pH 2 treatment, but slightly decreased. The role of Pi, which might be functioning as a regulatory factor of cytoplasmic pH, a non-competitive inhibitor of the H+-pumps of both the plasma membrane and tonoplast is discussed.

The 135-kDa actin-bundling protein from lily pollen tubes arranges F-actin into bundles with uniform polarity

A plant 135-kDa actin-bundling protein (P-135-ABP) isolated from pollen tubes of Lilium longiflorum (Thunb.) binds stoichiometrically to F-actin filaments and bundles them in vitro (E. Yokota et al., 1998, Plant Physiol. 116: 1421-1429). To further understand the mechanism of actin-filament bundle formation by P-135-ABP, the polarity of each F-actin filament in bundles was examined using myosin subfragment 1 (S-1). Dissociation of F-actin filaments from bundles organized by P-135-ABP was induced by S-1. However, F-actin filaments that remained in a bundle and decorated by S-1 showed uniform polarity. These results indicate that P-135-ABP arranges F-actin filaments into bundles with uniform polarity and consequently plays a key role in the orientation of cytoplasmic streaming in pollen tubes.

Genetic diversities of hantaviruses among rodents in Hokkaido, Japan and Far East Russia

Seroepizootiologic surveys among wild rodents were carried out in Japan and Far East Russia in 1995 and 1996. Seropositive animals were only identified in Clethrionomys rufocanus (23/134) in Hokkaido, Japan. On the other hand, seropositives were identified in C. rufocanus (1/8), Apodemus agrarius (2/66), Apodemus spp. (2/26) and Microtus fortis (3/22) in Vladivostok, Far East Russia. Total RNA was isolated from lungs of seropositive animals and the S genome segments were amplified by PCR, cloned and sequenced. The S and M genomes of hantavirus, derived from Japanese C. rufocanus (Tobetsu genotype), were most closely related with Puumala viruses (76-79% nucleotide and 95% amino acid identities for S genome, 70-78% nucleotide and 87-92% amino acid identities for M genome). The recombinant nucleocapsid protein of Tobetsu genotype was antigenically quite similar with that of Sotkamo. These suggest that the virus endemic in Japanese C. rufocanus belongs to Puumala virus. Phylogenetic analysis indicates that the genotype forms a distinct lineage within Puumala viruses. Partial S segment (1-1251 nt), derived from seropositive M. fortis in Vladivostok, was sequenced and analyzed. The S genome segment, which was designated Vladivostok genotype, was most closely related with Khabarovsk virus (79% nucleotide and 90% amino acid identities) which was isolated from M. fortis.

Inhibitory regulation of higher-plant myosin by Ca2+ ions

Myosin isolated from the pollen tubes of lily (Lilium longiflorum) is composed of a 170-kD heavy chain (E. Yokota and T. Shimmen [1994] Protoplasma 177: 153-162). Both the motile activity in vitro and the F-actin-stimulated ATPase activity of this myosin were inhibited by Ca2+ at concentrations higher than 10(-6) M. In the Ca2+ range between 10(-6) and 10(-5) M, inhibition of the motile activity was reversible. In contrast, inhibition by more than 10(-5) M Ca2+ was not reversible upon Ca2+ removal. An 18-kD polypeptide that showed the same mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as that of spinach calmodulin (CaM) was present in this myosin fraction. This polypeptide showed a mobility shift in sodium dodecyl sulfate-polyacrylamide gel electrophoresis in a Ca2+-dependent manner. Furthermore, this polypeptide was recognized by antiserum against spinach CaM. By immunoprecipitation using antiserum against the 170-kD heavy chain, the 18-kD polypeptide was coprecipitated with the 170-kD heavy chain, provided that the Ca2+ concentration was low, indicating that this 18-kD polypeptide is bound to the 170-kD myosin heavy chain. However, the 18-kD polypeptide was dissociated from the 170-kD heavy chain at high Ca2+ concentrations, which irreversibly inhibited the motile activity of this myosin. From these results, it is suggested that the 18-kD polypeptide, which is likely to be CaM, is associated with the 170-kD heavy chain as a light chain. It is also suggested that this polypeptide is involved in the regulation of this myosin by Ca2+. This is the first biochemical basis, to our knowledge, for Ca2+ regulation of cytoplasmic streaming in higher plants.

[Hemophagocytic syndrome in a patient with rheumatoid arthritis]

A 62-year-old man with 16 year-history of rheumatoid arthritis (RA) was admitted due to progressive pancytopenia, general fatigue, and high fever. He was treated with 5 mg methotrexate weekly in RA. His bone marrow examination revealed a decreased nuclear cell count (2.1 x 10(4)/microliter), megakaryocyte count (16/microliter), and macrophages phagocytizing blood cells (13.2%), indicating the presence of hemophagocytic syndrome. No infections agent was detected in cultures derived from his blood or other sources. The serological tests for several viruses revealed no obvious viral etiology. The systemic lymphonodes were not swelling. Administration of 40 mg prednisolone daily improved his abnormal hematological findings. This is a case of RA accompanied by hemophagocytic syndrome, which is a rare complication of RA.

Purification of an actin-binding protein composed of 115-kDa polypeptide from pollen tubes of lily

From lily pollen tubes, an actin-binding protein composed of 115-kDa polypeptide was purified sequentially by co-precipitation method with F-actin, hydroxylapatite column, gel filtration column and DE-52 ion exchange column chromatography. This component displayed a tendency to aggregate in solutions of low ionic strength, indicating a hydrophilic characteristic. Under physiological ionic conditions, this component bound to F-actin in an actin-concentration-dependent was saturable manner. Binding of this component to F-actin was independent of ATP and Ca(2+)-concentrations. Fluorescent microscopy revealed that F-actin labeled with rhodamine-phalloidin showed bundling in the presence of this component. Judging from the lack of antibody cross-reactivity, this component does not seem to be related to alpha-actinin of skeletal muscle and plant 135-kDa actin-bundling protein. Therefore, this component is the F-actin binding protein, which has not been identified thus far in plant cells.

[Acute mitral regurgitation caused by malignant lymphoma of the posterior mediastinum]

An 82-year-old man was admitted to our hospital in September 1996 due to dysphagia and cardiomegaly. Physical examination detected the fourth heart sound and a Levine III/VI systolic murmur in the cardiac apex. Surface lymph nodes were not palpable. LDH 662 IU/I was detected by laboratory examinations, and ultrasound cardiography showed grade 3 mitral regurgitation. Computed tomography revealed a huge mass in the posterior mediastinum, pressing the heart from the posterior direction. Thereafter, a left pleural effusion developed and aspiration was performed. Cytological examination of the fluid showed clusters of lymphoid cells with a positive immunophenotype for CD10, CD19 and HLA-DR. Chromosome analysis revealed complex abnormal karyotypes including t(8;14) (q24;32). A diagnosis of B cell lymphoma was made, and combination chemotherapy consisting of cyclophosphamide, THP-adriamycin, vincristine, and prednisolone was initiated. The patient's mass disappeared promptly, and his mitral reguration subsided. We reported this case because malignant lymphoma of the posterior mediastinum is rare, and because we are unaware of any previous reports of malignant lymphoma causing acute mitral regurgitation.

[A case of Sjögren's syndrome associated with advanced hemolytic anemia caused by worsening autoimmune cholangiopathy]

We report a rate case of autoimmune cholangiopathy (AIC) and autoimmune hemolytic anemia (AIHA) in a patient with Sjögren's syndrome. A 59-year-old woman was admitted to Matsuyama Red Cross Hospital in September 1996 because of worsening liver dysfunction. She had suffered from keratoconjunctivitis sicca and xerostomia and had been diagnosed as having Sjögren's syndrome in February 1994, based on histological examination of the minor salivary gland and sialography, and positivity for SS-A and SS-B antibody. Liver dysfunction had first become evident in September 1995. Histological examination of a liver biopsy specimen obtained by laparoscopy showed that the structure of the hepatic lobules was mostly preserved, whereas most of the biliary ducts were transformed, being consistent with AIC. On admission, the patient was given 40 mg of prednisolone. Although the serum transaminase level decreased, jaundice persisted and hemolytic anemia developed. Further administration of 60 mg of prednisolone and plasmapheresis ameliorated the hemolytic anemia and cured the jaundice. We consider that an increased immunological response caused by the worsening AIC might have played a role in the development of AIHA in the present case.

[A case of the active intestinal tuberculosis detected during the examination of the right pleural effusion]

A 76-year-old female was admitted to our hospital because of fever and the right pleural effusion. On the analysis of pleural effusion, the total cell count was 6720/microliter with 95% lymphocytes, and ADA was 38.1 U/l. The culture of pleural effusion was negative, and the smear and PCR for Mycobacterium were also negative. For examinations, we performed eterography that showed cicatricial strictures of intestine. X-ray examination of the colonated colonoscopy showed ulcers (circular type), shortening of the colon, Bauhin's value insufficiency and diverticulum-like deformity. Then, she was diagnosed as intestinal tuberculosis. The smear and PCR of biopsy specimens from the lesion were positive, and antituberculotic therapy was effective. Finally, the culture of pleural effusion for Mycobacterium tuberculosis was positive after 8 weeks. We thought intestinal examination may be useful for the diagnosis of tuberculosis, when lymphocyte-rich exudative pleural effusion of unknown etiology is seen.

Actin-bundling protein isolated from pollen tubes of lily. Biochemical and immunocytochemical characterization

A 135-kD actin-bundling protein was purified from pollen tubes of lily (Lilium longiflorum) using its affinity to F-actin. From a crude extract of the pollen tubes, this protein was coprecipitated with exogenously added F-actin and then dissociated from F-actin by treating it with high-ionic-strength solution. The protein was further purified sequentially by chromatography on a hydroxylapatite column, a gel-filtration column, and a diethylaminoethyl-cellulose ion-exchange column. In the present study, this protein is tentatively referred to as P-135-ABP (Plant 135-kD Actin-Bundling Protein). By the elution position from a gel-filtration column, we estimated the native molecular mass of purified P-135-ABP to be 260 kD, indicating that it existed in a dimeric form under physiological conditions. This protein bound to and bundled F-actin prepared from chicken breast muscle in a Ca2+-independent manner. The binding of 135-P-ABP to actin was saturated at an approximate stoichiometry of 26 actin monomers to 1 dimer of P-135-ABP. By transmission electron microscopy of thin sections, we observed cross-bridges between F-actins with a longitudinal periodicity of 31 nm. Immunofluorescence microscopy using rhodamine-phalloidin and antibodies against the 135-kD polypeptide showed that P-135-ABP was colocalized with bundles of actin filaments in lily pollen tubes, leading us to conclude that it is the factor responsible for bundling the filaments.

[Neoplastic angioendotheliosis with Roth's spots]

A 81-year-old woman was admitted with fever, anemia and an elevation of serum LDH on September, 1995. She had anasarca and various abnormalities of the ocular fundus including Roth's spots. Skin eruption and psycho-neurological abnormalities were not seen. Laboratory data exhibited Hb 7.6g/dl, Plt 9.3 x 10(4)/microliters, WBC 6,300/microliters and LDH 1932 IU/l. Antibiotics, antituberculotic drugs and steroids were not effective and she died on October, 1995 with heart failure. An autopsy revealed that the small vessels of lungs, kidneys and the mucosa of the bladder and the gastrointestinal tract were filled with large mononuclear cells. Immunohistochemically these cells were positive in LCA and L26 stains, and negative in UCHL-1 stains. There fore this case was finally diagnosed as neoplastic angioendotheliosis (NAE). Although there has been no case report of NAE with Roth's spots previously, there is the possibility that Roth's spots appeared as a sign of vascular occlusion due to NAE. Roth's spots may be noteworthy as a sign of NAE that has few clinical features.

Purealin blocks the sliding movement of sea urchin flagellar axonemes by selective inhibition of half the ATPase activity of axonemal dyneins

Ciliary and flagellar movements are explained by active sliding between the outer doublet microtubules of an axoneme via their inner and outer dynein arms. Purealin, a novel bioactive principle of a sea sponge Psammaplysilla purea, blocked the motility of Triton-demembranated sea urchin sperm flagella within 5 min at concentrations above 20 microM. In a similar concentration range, purealin blocked the sliding movement of the flagellar axonemes in vitro within a few minutes judging from the turbidity measurements. The ATPase activity of axonemes was partially inhibited by purealin in a concentration-dependent manner. The maximum inhibition reached approximately 50% at concentrations above 20 microM, indicating that half the axonemal ATPase activity is sensitive to purealin. Similar results were observed on the ATPase activity of outer-arm-depleted axonemes and that of a mixture of 21S dynein and salt-extracted axonemes. On the other hand, ATPase activity of isolated 21S dynein was not inhibited by purealin. The inhibitory action of purealin on the axonemal ATPases was reversed by dilution of purealin. The effect of purealin on the double-reciprocal plot of the ATPase activity as a function of ATP concentrations showed that the inhibition was not a competitive type. In accord with this finding, purealin did not affect the vanadate-mediated UV photocleavage of axonemal dyneins. These results suggest that purealin binds reversibly to a site other than the catalytic ATP-binding site and inhibits half the ATPase activity of axonemes. Taken together, our results suggest that purealin-sensitive ATPase activity of the dynein arms plays an essential role in generating the sliding movement of flagellar axonemes.

[Prosthetic endocarditis caused by Kingella denitrificans in a patient with diabetes mellitus]

Infective endocarditis caused by Kingella denitrificans occurs rarely. A review of the literature reveals only 6 cases of endocarditis caused by the bacillus. K. denitrificans is normally a commensal of the upper respiratory airways, may exceptionally be responsible for endocarditis. A case of possible prosthetic endocarditis caused by K. denitrificans is presented. A 78-year-old male with Type II diabetes was admitted to the hospital complaining of fever, a sore throat and arthralgia. He underwent replacement surgery of a St. Jude medical prosthesis for aortic stenosis at the age of 75. The only physical findings at admission were a temperature of 38.2 degrees C and murmurs of mild mitral regurgitation. The liver and spleen were not palpable, and there were no skin or eye lesions. Laboratory findings were as follows: white blood cell count 9500/microliters with 77% neutrophils, erythrocyte sedimentation rate 71 mm/h (Westergren), blood urea nitrogen 50.2 mg/dl, serum creatinine 1.7 mg/dl and C-reactive protein 22.2 mg/dl. The Gram-negative bacillus isolated from the blood was identified as K. denitrificans by the identification system, namely ID test.FN-20 rapid (Nissui, Japan). Although an echocardiogram detected no vegetation, infective endocarditis was diagnosed because the same bacillus was detected by separate blood cultures and an obvious source of infection was not found other than the prosthetic valve. Initial treatment was flomoxef, which was changed to Ampicillin 2 g/day after K. denitrificans was identified. Ampicillin continued for 6 weeks. The clinical course was good and he did not require further surgery. He has been afebrile for 2 years after completing treatment. This case represents the first report of prosthetic valve endocarditis caused by K. denitrificans in Japan.

Interaction of flagellar inner arm dynein isolated from sea urchin sperm with microtubules in the presence of ATP

We have isolated C/A dynein, which is considered to be a component of inner arms, from flagellar axonemes of sea urchin sperm (E. Yokota, I. Mabuchi, J. Cell Sci. 107, 345-351 (1994). C/A dynein binds to and bundles the microtubules in the absence of ATP. In contrast to outer arm 21S dynein, C/A dynein is not released from the microtubules in the presence of ATP (E. Yokota, I. Mabuchi, J. Cell Sci. 107, 353-361 (1994)). We further investigated the interaction of C/A dynein with microtubules in the presence of ATP. The turbidity at 350 nm of a mixture of C/A dynein and microtubules increased by the addition of ATP. Both the initial rate and final extent of the turbidity increase were dependent on C/A dynein or ATP concentration and were inhibited by vanadate. ATP hydrolysis by C/A dynein was linear during the time course of the turbidity increase. Negative staining electron microscopy revealed that microtubular bundles which formed in the presence of C/A dynein became thicker and longer after addition of ATP. Furthermore, sliding movements of microtubule(s) in the individual bundles were observed in the presence of ATP. This mode of interaction of C/A dynein with microtubules was distinct from that of flagellar or ciliary dyneins reported so far. These results suggest that C/A dynein, as a component of inner arms, may play a distinct role in the flagellar movement of sea urchin sperm.

Is outer arm dynein intermediate chain 1 multifunctional?

The outer arm dynein of sea urchin sperm axoneme contains three intermediate chains (IC1, IC2, and IC3; M(r) 128,000, 98,000, and 74,000, respectively). IC2 and IC3 are members of the WD family; the WD motif is responsible for a protein-protein interaction. We describe here the molecular cloning of IC1. IC1 has a unique primary structure, the N-terminal part is homologous to the sequence of thioredoxin, the middle part consists of three repetitive sequences homologous to the sequence of nucleoside diphosphate kinase, and the C-terminal part contains a high proportion of negatively charged glutamic acid residues. Thus, IC1 is a novel dynein intermediate chain distinct from IC2 and IC3 and may be a multifunctional protein. The thioredoxin-related part of IC1 is more closely related to those of two redox-active Chlamydomonas light chains than thioredoxin. Antibodies were prepared against the N-terminal and middle domains of IC1 expressed as His-tagged proteins in bacteria. These antibodies cross-reacted with some dynein polypeptides (potential homologues of IC1) from distantly related species. We propose here that the three intermediate chains are the basic core units of sperm outer arm dynein because of their ubiquitous existence. The recombinant thioredoxin-related part of IC1 and outer arm dyneins from sea urchin and distantly related species were specifically bound to and eluted from a phenylarsine oxide affinity column with 2-mercaptoethanol, indicating that they contain vicinal dithiols competent to undergo reversible oxidation/reduction.

Fatal cerebral infarction in an asymptomatic young patient with primary antiphospholipid syndrome

An 18-year-old woman with primary antiphospholipid syndrome developed a major cerebral infarction leading to brain death despite intensive treatment with steroids, urokinase, glyceol and heparin. Fatal strokes associated with this syndrome are rare. A computed tomographic scan of the brain suggested occlusion of the main trunk of the right middle cerebral artery. The titer of antibodies against cardiolipin/ beta 2-glycoprotein I complex in serum was extremely high.

C/A dynein isolated from sea urchin sperm flagellar axonemes. Enzymatic properties and interaction with microtubules

C/A dynein is a novel dynein isolated from sea urchin sperm flagellar axonemes. It is composed of C and A heavy chains and some additional lower molecular mass polypeptide chains. The characterization of ATPase activity and the interaction of this dynein with microtubules polymerized from calf brain tubulin were investigated in this study. The ATPase activity of C/A dynein (0.3-0.4 mumol Pi/min per mg) was about one half that of outer arm 21 S dynein (0.6-0.8 mumol Pi/min per mg) at 25 degrees C. Vanadate inhibited the ATPase activity with a half-maximal inhibition at 1 microM. C/A dynein absorbed to the glass surface was able to translocate the microtubules towards its plus end. The velocity of the microtubule movement in the presence of 1 mM ATP was 4.0 to 4.5 microns/s at 22 degrees C. C/A dynein binds to and bundles the microtubules even in the presence of ATP. Cross-bridges were found between adjacent microtubules in the bundle with an axial periodicity of about 24 nm. The ATPase activity of C/A dynein was enhanced up to several-fold by the microtubules at concentration as low as 1 mg/ml. On the other hand, 21 S dynein bound to the microtubules with 24 nm axial periodicity only in the absence of ATP. Its ATPase activity was not activated by the microtubules. From these results, it is concluded that the manner of interaction with microtubules of C/A dynein is different from that of the outer arm dynein.

C/A dynein isolated from sea urchin sperm flagellar axonemes. Enzymatic properties and interaction with microtubules

C/A dynein is a novel dynein isolated from sea urchin sperm flagellar axonemes. It is composed of C and A heavy chains and some additional lower molecular mass polypeptide chains. The characterization of ATPase activity and the interaction of this dynein with microtubules polymerized from calf brain tubulin were investigated in this study. The ATPase activity of C/A dynein (0.3-0.4 mumol Pi/min per mg) was about one half that of outer arm 21 S dynein (0.6-0.8 mumol Pi/min per mg) at 25 degrees C. Vanadate inhibited the ATPase activity with a half-maximal inhibition at 1 microM. C/A dynein absorbed to the glass surface was able to translocate the microtubules towards its plus end. The velocity of the microtubule movement in the presence of 1 mM ATP was 4.0 to 4.5 microns/s at 22 degrees C. C/A dynein binds to and bundles the microtubules even in the presence of ATP. Cross-bridges were found between adjacent microtubules in the bundle with an axial periodicity of about 24 nm. The ATPase activity of C/A dynein was enhanced up to several-fold by the microtubules at concentration as low as 1 mg/ml. On the other hand, 21 S dynein bound to the microtubules with 24 nm axial periodicity only in the absence of ATP. Its ATPase activity was not activated by the microtubules. From these results, it is concluded that the manner of interaction with microtubules of C/A dynein is different from that of the outer arm dynein.

Isolation and characterization of a novel dynein that contains C and A heavy chains from sea urchin sperm flagellar axonemes

A novel dynein (C/A dynein), which is composed of C and A heavy chains, two intermediate chains and several light chains, was isolated from sea urchin sperm flagella. The C/A dynein was released by the treatment with 0.7 M NaCl plus 5 mM ATP from the axonemes depleted of outer arm 21 S dynein. Sedimentation coefficient of this dynein was estimated by sucrose density gradient centrifugation to be 22–23 S. The C/A dynein particle appeared to be composed of three distinct domains; two globular head domains and one rod domain as seen by negative staining electron microscopy. The mobility of ‘A’ heavy chain of C/A dynein on SDS-gel electrophoresis was similar to that of A heavy chains (A alpha and A beta) of 21 S dynein. However, UV-cleavage patterns of C and A heavy chains of C/A dynein were different from those of A heavy chains of 21 S dynein. Furthermore, an antiserum raised against A heavy chain of C/A dynein did not crossreact with A heavy chains of 21 S dynein. Under the conditions in which the C/A dynein was released, some of inner arms were removed concomitantly from axonemes as observed by electron microscopy. These results suggested that C/A dynein is a component of the inner arms.

In-vitro evaluation of the four beta-lactamase inhibitors: BRL42715, clavulanic acid, sulbactam, and tazobactam

The in-vitro synergic activities of BRL42715, a new beta-lactamase inhibitor, clavulanic acid, sulbactam, and tazobactam combined with ampicillin, piperacillin, cephalothin, or cefoperazone were tested against various bacteria producing known types of beta-lactamase. BRL42715 showed the best synergistic activity among the inhibitors tested against strains producing penicillinases of type I, II, III, V, and that from Klebsiella pneumoniae, cephalosporinases, and oxyiminocephalosporinases (except that from Klebsiella oxytoca). Clavulanic acid combined with the beta-lactams tested showed the best synergic activity of the inhibitors against strains producing type IV penicillinase and oxyiminocephalosporinase from K. oxytoca. The 50% inhibitory doses of BRL42715 were superior to those of clavulanic acid against various types of beta-lactamases except for type IV penicillinase and the oxyiminocephalosporinase from K. oxytoca. The inhibitory activity of BRL42715 against cephalosporinases from various bacteria was 10(4) to 10(6)-fold greater than that of clavulanic acid. The synergic effects of BRL42715 and clavulanic acid on the activity of piperacillin were compared against six clinical isolates of bacteria resistant to piperacillin. The synergic activity of BRL42715 was greater than that of clavulanic acid in all six isolates.

[Disappearance of Philadelphia chromosomes after remission induction in lymphoid crisis of chronic myelogenous leukemia]

The authors report a rare case of chronic myelogenous leukemia (CML) in which the Ph1 clone disappeared after remission induction of lymphoid crisis. A 58-year-old man was admitted to our hospital because of fever in July 1988. The white cell count was elevated. Bone marrow aspirate showed hypercellularity with myeloid hyperplasia. In the chromosomal analysis, Ph1 chromosomes were detected in 100% of bone marrow cells analysed. Diagnosis of CML was made and treatment was initiated with recombinant interferon-alpha 2a. Hematological remission without cytogenetic improvement was achieved. In March 1990 he developed lymphoid crisis with proliferation of CD10-positive cells. The chromosomal analysis revealed additional abnormalities including, 45, X, -Y, t(9;22) (q34;q11), +1, -8. With vincristine 0.6 mgX4, pirarubicin 15 mgX4, dexamethasone 40 mgX4 therapy complete remission was obtained. In December 1990 the Ph1 positive clone completely disappeared judging from normal karyotypes in the chromosomal analysis and the disappearance of M-bcr gene rearrangement.