Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station

Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric Electron Telescope (CALET) on the International Space Station. The instrument, consisting of a charge detector, an imaging calorimeter, and a total absorption calorimeter with a total depth of 30 radiation lengths at normal incidence and a fine shower imaging capability, is optimized to measure the all-electron spectrum well into the TeV region. Because of the excellent energy resolution (a few percent above 10 GeV) and the outstanding e/p separation (10^{5}), CALET provides optimal performance for a detailed search of structures in the energy spectrum. The analysis uses data up to the end of 2022, and the statistics of observed electron candidates has increased more than 3 times since the last publication in 2018. By adopting an updated boosted decision tree analysis, a sufficient proton rejection power up to 7.5 TeV is achieved, with a residual proton contamination less than 10%. The observed energy spectrum becomes gradually harder in the lower energy region from around 30 GeV, consistently with AMS-02, but from 300 to 600 GeV it is considerably softer than the spectra measured by DAMPE and Fermi-LAT. At high energies, the spectrum presents a sharp break around 1 TeV, with a spectral index change from -3.15 to -3.91, and a broken power law fitting the data in the energy range from 30 GeV to 4.8 TeV better than a single power law with 6.9 sigma significance, which is compatible with the DAMPE results. The break is consistent with the expected effects of radiation loss during the propagation from distant sources (except the highest energy bin). We have fitted the spectrum with a model consistent with the positron flux measured by AMS-02 below 1 TeV and interpreted the electron+positron spectrum with possible contributions from pulsars and nearby sources. Above 4.8 TeV, a possible contribution from known nearby supernova remnants, including Vela, is addressed by an event-by-event analysis providing a higher proton-rejection power than a purely statistical analysis.

Erratum: Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station [Phys. Rev. Lett. 130, 211001 (2023)]

This corrects the article DOI: 10.1103/PhysRevLett.130.211001.

Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station

We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6 yr, corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical "drift model" of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.

Direct Measurement of the Cosmic-Ray Helium Spectrum from 40 GeV to 250 TeV with the Calorimetric Electron Telescope on the International Space Station

We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis spans from October 13, 2015, to April 30, 2022 (2392 days). The very wide dynamic range of CALET allowed for the collection of helium data over a large energy interval, from ∼40  GeV to ∼250  TeV, for the first time with a single instrument in low Earth orbit. The measured spectrum shows evidence of a deviation of the flux from a single power law by more than 8σ with a progressive spectral hardening from a few hundred GeV to a few tens of TeV. This result is consistent with the data reported by space instruments including PAMELA, AMS-02, and DAMPE and balloon instruments including CREAM. At higher energy we report the onset of a softening of the helium spectrum around 30 TeV (total kinetic energy). Though affected by large uncertainties in the highest energy bins, the observation of a flux reduction turns out to be consistent with the most recent results of DAMPE. A double broken power law is found to fit simultaneously both spectral features: the hardening (at lower energy) and the softening (at higher energy). A measurement of the proton to helium flux ratio in the energy range from 60  GeV/n to about 60  TeV/n is also presented, using the CALET proton flux recently updated with higher statistics.

Cosmic-Ray Boron Flux Measured from 8.4 GeV/n to 3.8 TeV/n with the Calorimetric Electron Telescope on the International Space Station

We present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux in an energy interval from 8.4  GeV/n to 3.8  TeV/n based on the data collected by the Calorimetric Electron Telescope (CALET) during ∼6.4  yr of operation on the International Space Station. An update of the energy spectrum of carbon is also presented with an increase in statistics over our previous measurement. The observed boron flux shows a spectral hardening at the same transition energy E_{0}∼200  GeV/n of the C spectrum, though B and C fluxes have different energy dependences. The spectral index of the B spectrum is found to be γ=-3.047±0.024 in the interval 25<E<200  GeV/n. The B spectrum hardens by Δγ_{B}=0.25±0.12, while the best fit value for the spectral variation of C is Δγ_{C}=0.19±0.03. The B/C flux ratio is compatible with a hardening of 0.09±0.05, though a single power-law energy dependence cannot be ruled out given the current statistical uncertainties. A break in the B/C ratio energy dependence would support the recent AMS-02 observations that secondary cosmic rays exhibit a stronger hardening than primary ones. We also perform a fit to the B/C ratio with a leaky-box model of the cosmic-ray propagation in the Galaxy in order to probe a possible residual value λ_{0} of the mean escape path length λ at high energy. We find that our B/C data are compatible with a nonzero value of λ_{0}, which can be interpreted as the column density of matter that cosmic rays cross within the acceleration region.

Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station

A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observation of a softening of the spectrum above 10 TeV is reported. The analysis is based on the data collected during ∼6.2  years of smooth operations aboard the International Space Station and covers a broader energy range with respect to the previous proton flux measurement by CALET, with an increase of the available statistics by a factor of ∼2.2. Above a few hundred GeV we confirm our previous observation of a progressive spectral hardening with a higher significance (more than 20 sigma). In the multi-TeV region we observe a second spectral feature with a softening around 10 TeV and a spectral index change from -2.6 to -2.9 consistently, within the errors, with the shape of the spectrum reported by DAMPE. We apply a simultaneous fit of the proton differential spectrum which well reproduces the gradual change of the spectral index encompassing the lower energy power-law regime and the two spectral features observed at higher energies.

Direct Measurement of the Nickel Spectrum in Cosmic Rays in the Energy Range from 8.8 GeV/n to 240 GeV/n with CALET on the International Space Station

The relative abundance of cosmic ray nickel nuclei with respect to iron is by far larger than for all other transiron elements; therefore it provides a favorable opportunity for a low background measurement of its spectrum. Since nickel, as well as iron, is one of the most stable nuclei, the nickel energy spectrum and its relative abundance with respect to iron provide important information to estimate the abundances at the cosmic ray source and to model the Galactic propagation of heavy nuclei. However, only a few direct measurements of cosmic-ray nickel at energy larger than ∼3  GeV/n are available at present in the literature, and they are affected by strong limitations in both energy reach and statistics. In this Letter, we present a measurement of the differential energy spectrum of nickel in the energy range from 8.8  to 240  GeV/n, carried out with unprecedented precision by the Calorimetric Electron Telescope (CALET) in operation on the International Space Station since 2015. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The particle's energy is measured by a homogeneous calorimeter (1.2 proton interaction lengths, 27 radiation lengths) preceded by a thin imaging section (3 radiation lengths) providing tracking and energy sampling. This Letter follows our previous measurement of the iron spectrum [1O. Adriani et al. (CALET Collaboration), Phys. Rev. Lett. 126, 241101 (2021).PRLTAO0031-900710.1103/PhysRevLett.126.241101], and it extends our investigation on the energy dependence of the spectral index of heavy elements. It reports the analysis of nickel data collected from November 2015 to May 2021 and a detailed assessment of the systematic uncertainties. In the region from 20 to 240  GeV/n our present data are compatible within the errors with a single power law with spectral index -2.51±0.07.

Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV/n to 2.0 TeV/n with the Calorimetric Electron Telescope on the International Space Station

The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this Letter a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10  GeV/n to 2.0  TeV/n allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50  GeV/n to 2  TeV/n our present data are compatible with a single power law with spectral index -2.60±0.03.

Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV/n to 2.2 TeV/n with the Calorimetric Electron Telescope on the International Space Station

In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope on the International Space Station from October 2015 to October 2019. Analysis, including the detailed assessment of systematic uncertainties, and results are reported. The energy spectra are measured in kinetic energy per nucleon from 10  GeV/n to 2.2  TeV/n with an all-calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length. The observed carbon and oxygen fluxes show a spectral index change of ∼0.15 around 200  GeV/n established with a significance >3σ. They have the same energy dependence with a constant C/O flux ratio 0.911±0.006 above 25  GeV/n. The spectral hardening is consistent with that measured by AMS-02, but the absolute normalization of the flux is about 27% lower, though in agreement with observations from previous experiments including the PAMELA spectrometer and the calorimetric balloon-borne experiment CREAM.

Direct Measurement of the Cosmic-Ray Proton Spectrum from 50 GeV to 10 TeV with the Calorimetric Electron Telescope on the International Space Station

In this paper, we present the analysis and results of a direct measurement of the cosmic-ray proton spectrum with the CALET instrument onboard the International Space Station, including the detailed assessment of systematic uncertainties. The observation period used in this analysis is from October 13, 2015 to August 31, 2018 (1054 days). We have achieved the very wide energy range necessary to carry out measurements of the spectrum from 50 GeV to 10 TeV covering, for the first time in space, with a single instrument the whole energy interval previously investigated in most cases in separate subranges by magnetic spectrometers (BESS-TeV, PAMELA, and AMS-02) and calorimetric instruments (ATIC, CREAM, and NUCLEON). The observed spectrum is consistent with AMS-02 but extends to nearly an order of magnitude higher energy, showing a very smooth transition of the power-law spectral index from -2.81±0.03 (50-500 GeV) neglecting solar modulation effects (or -2.87±0.06 including solar modulation effects in the lower energy region) to -2.56±0.04 (1-10 TeV), thereby confirming the existence of spectral hardening and providing evidence of a deviation from a single power law by more than 3σ.

The CALorimetric Electron Telescope (CALET) on the International Space Station: Results from the First Two Years of Operation

The CALorimetric Electron Telescope (CALET) space experiment, which has been developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission on the International Space Station (ISS). The primary goals of the CALET mission include investigation of possible nearby sources of high-energy electrons, detailed study of galactic cosmic-ray acceleration and propagation, and search for dark matter signatures. With a long-term observation onboard the ISS, the CALET experiment measures the flux of cosmic-ray electrons (including positrons) up to 20 TeV, gamma-rays to 10 TeV, and nuclei up to 1,000 TeV based on its charge separation capability from Z = 1 to 40. Since the start of science operation in mid-October, 2015, a continuous observation has been maintained without any major interruptions. The number of triggered events over 10 GeV is nearly 20 million per month. By using the data obtained during the first two-years, here we present a summary of the CALET observations: 1) Electron+positron energy spectrum, 2) Nuclei analysis, 3) Gamma-ray observation with a characterization of the on-orbit performance. The search results for the electromagnetic counterparts of LIGO/Virgo gravitational wave events are also discussed.

Extended Measurement of the Cosmic-Ray Electron and Positron Spectrum from 11 GeV to 4.8 TeV with the Calorimetric Electron Telescope on the International Space Station

Extended results on the cosmic-ray electron + positron spectrum from 11 GeV to 4.8 TeV are presented based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station utilizing the data up to November 2017. The analysis uses the full detector acceptance at high energies, approximately doubling the statistics compared to the previous result. CALET is an all-calorimetric instrument with a total thickness of 30 X_{0} at normal incidence and fine imaging capability, designed to achieve large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum in the region below 1 TeV shows good agreement with Alpha Magnetic Spectrometer (AMS-02) data. In the energy region below ∼300  GeV, CALET's spectral index is found to be consistent with the AMS-02, Fermi Large Area Telescope (Fermi-LAT), and Dark Matter Particle Explorer (DAMPE), while from 300 to 600 GeV the spectrum is significantly softer than the spectra from the latter two experiments. The absolute flux of CALET is consistent with other experiments at around a few tens of GeV. However, it is lower than those of DAMPE and Fermi-LAT with the difference increasing up to several hundred GeV. The observed energy spectrum above ∼1  TeV suggests a flux suppression consistent within the errors with the results of DAMPE, while CALET does not observe any significant evidence for a narrow spectral feature in the energy region around 1.4 TeV. Our measured all-electron flux, including statistical errors and a detailed breakdown of the systematic errors, is tabulated in the Supplemental Material in order to allow more refined spectral analyses based on our data.

Energy Spectrum of Cosmic-Ray Electron and Positron from 10 GeV to 3 TeV Observed with the Calorimetric Electron Telescope on the International Space Station

First results of a cosmic-ray electron and positron spectrum from 10 GeV to 3 TeV is presented based upon observations with the CALET instrument on the International Space Station starting in October, 2015. Nearly a half million electron and positron events are included in the analysis. CALET is an all-calorimetric instrument with total vertical thickness of 30 X_{0} and a fine imaging capability designed to achieve a large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum over 30 GeV can be fit with a single power law with a spectral index of -3.152±0.016 (stat+syst). Possible structure observed above 100 GeV requires further investigation with increased statistics and refined data analysis.

Transformer 2β and miR-204 regulate apoptosis through competitive binding to 3' UTR of BCL2 mRNA

RNA-binding proteins and microRNAs are potent post-transcriptional regulators of gene expression. Human transformer 2β (Tra2β) is a serine/arginine-rich-like protein splicing factor and is now implicated to have wide-ranging roles in gene expression as an RNA-binding protein. RNA immunoprecipitation (RIP) with an anti-Tra2β antibody and microarray analysis identified a subset of Tra2β-associated mRNAs in HCT116 human colon cancer cells, many of which encoded cell death-related proteins including Bcl-2 (B-cell CLL/lymphoma 2). Tra2β knockdown in HCT116 cells decreased Bcl-2 expression and induced apoptosis. Tra2β knockdown accelerated the decay of BCL2α mRNA that encodes Bcl-2 and full-length 3' UTR, while it did not affect the stability of BCL2β mRNA having a short, alternatively spliced 3' UTR different from BCL2α 3' UTR. RIP assays with anti-Tra2β and anti-Argonaute 2 antibodies, respectively, showed that Tra2β bound to BCL2α 3' UTR, and that Tra2β knockdown facilitated association of miR-204 with BCL2α 3' UTR. The consensus sequence (GAA) for Tra2β-binding lies within the miR-204-binding site of BCL2 3' UTR. Mutation of the consensus sequence canceled the binding of Tra2β to BCL2 3' UTR without disrupting miR-204-binding to BCL2 3' UTR. Transfection of an anti-miR-204 or introduction of three-point mutations into the miR-204-binding site increased BCL2 mRNA and Bcl-2 protein levels. Inversely, transfection of precursor miR-204 reduced their levels. Experiments with Tra2β-silenced or overexpressed cells revealed that Tra2β antagonized the effects of miR-204 and upregulated Bcl-2 expression. Furthermore, TRA2β mRNA expression was significantly upregulated in 22 colon cancer tissues compared with paired normal tissues and positively correlated with BCL2 mRNA expression. Tra2β knockdown in human lung adenocarcinoma cells (A549) increased their sensitivity to anticancer drugs. Taken together, our findings suggest that Tra2β regulates apoptosis by modulating Bcl-2 expression through its competition with miR-204. This novel function may have a crucial role in tumor growth.

Xanthoma disseminatum with large plaques confined to the back, pulmonary involvement and multiple intestinal xanthomas

Xanthoma disseminatum (XD) is a rare benign mucocutaneous xanthomatosis that is classified as a benign non-Langerhans cell histiocytosis. We report a 68-year-old man who presented with peculiar, large plaques confined to the back 7 years after the onset of cranial diabetes insipidus. Histopathological features of the cutaneous lesions were typical of XD. The patient had lower respiratory tract involvement with histiocytic infiltrates, which was unresponsive to various treatments and resulted in a fatal outcome. Gastrointestinal endoscopies revealed multiple xanthomas in the sigmoid colon and the rectum. To our knowledge, this is the first reported case of intestinal xanthomas associated with XD.

Effects of the quantity of water and milk ingested concomitantly with AS-924, a novel ester-type cephem antibiotic, on its pharmacokinetics

The effect of the quantity of water ingested concomitantly with drugs, on the absorption of AS-924, a novel prodrug-type cephem antibiotic, was studied in five healthy adult volunteers by a cross-over method, using cefteram-pivoxil (CTER-PI) as the control drug. In addition, the effect of milk on the absorption of AS-924 was also investigated. The absorption of CTER-PI was significantly reduced when administered together with 30 ml of water compared with its absorption when administered together with 150 ml of water, whereas no such reduction was found in the case of AS-924. Ingestion of milk did not significantly affect the absorption of AS-924. These results confirm that absorption of AS-924 after oral administration is not likely to be affected by the quantity of water taken concomitantly with the drug, nor by milk.

Immunohistologic detection of the primary follicle (PF) in human fetal and newborn lymph node anlages

The primary follicle (PF) emerges as a globular nest of follicular dendritic cells (FDC) and lymphocytes in the lymph node anlage in the 16th gestational week. It increases in size with age but no germinal center is found until several months later, after birth. Using a panel of monoclonal antibodies, the authors have defined phenotypes of component cells of the PF. The PF contains a B-cell population including IgM+, CD20+, CD21+, and CD24+ cells, together with a T-cell population including CD3+, CD4+, CD5+, and CD8+ but no IgG+ cells. It also contains many CD5+ B cells and several IgD+ and alkaline phosphatase-positive cells but few CD15+, CD25+, CD30+, CD38+, and Ki-67+ cells. CD24+ and dendritic reticulum (DRC)-1+ cells show an irregular meshwork pattern in the PF. CD5+ B cells appear even before the formation of the PF and increase after formation of the PF. The lymphocytic phenotype of the PF is similar to that of the mantle zone of the secondary follicle. The phenotypic characteristics indicate that the PF appears as an aggregation of CD5+ B cells and plays an important role as the ancestor of the secondary follicle as well as helper T cells and FDC.

Necrotizing lymphadenitis: a clinicopathological and immunohistochemical study of four familial cases and five recurrent cases

We report the clinicopathological and immunohistological findings of nine cases of necrotizing lymphadenitis, consisting of four cases of familial infection and five cases of recurrence. Fever, cervical lymphadenopathy, leucopenia and swelling of the tonsils are characteristic clinical findings. Morphological features of the lymph nodes include the presence of immunoblasts, plasmacytoid T cells, histiocytes and macrophages, the latter with phagocytized nuclear debris derived from degenerated lymphocytes. However, granulocytes are generally absent. Ultrastructurally, tubuloreticular structures are observed not only in lymphoid cells, but in vascular endothelial cells. Immunological studies of peripheral blood using monoclonal antibodies disclose that CD 8+ (Leu 2a+; suppressor/cytotoxic) cells predominate at the onset, but they gradually decrease with the clinical course and the ratio of CD 4+: CD 8+ (helper:suppressor) increases as the disease progresses. However, in the affected lymph nodes, CD4+ (Leu 2a+: helper/inducer) cells often increase with the clinical progression, but the ratio of CD 4+:CD 8+ in the lymph nodes does not correlate with clinical progression. In addition, Ki-67+CD 8+ cells are more often seen than Ki-67+CD 4+ cells. It is suggested that necrotizing lymphadenitis is an infectious disease in which CD 4+ cells are disrupted and CD 8+ cells undergo transformation to blastoid cells. This results in a change in the ratio of T subsets.

Necrotizing lymphadenitis: a review of clinicopathological, immunohistochemical and ultrastructural studies

Necrotizing lymphadenitis (NEL) has been reported to be a reactive process described under differing terminology by Fujimoto et al. (1972), Kikuchi (1972), Wakasa et al. (1973) and other Japanese pathologists. Recently, this type of lymphadenitis has also been reported in America and Europe. In Japan, NEL is observed more frequently in the northern area, however, no characteristic seasonal occurrence has been noted. The disease affects young females more than males, particularly from the third and fourth decades onwards. Common cold-like symptoms, lymphadenopathy of the cervical region and leukopenia are characteristic clinical findings in the early stages. Morphological features of the involved lymph nodes include the presence of numerous immunoblasts, histiocytes and macrophages, the latter with phagocytized nuclear debris derived from degenerated lymphocytes. However, granulocytes are generally absent. Tubular inclusions are observed ultrastructurally. Immunohistochemical studies of peripheral blood using monoclonal antibodies have revealed that the helper/suppressor (Leu 3a/2a) ratio increases gradually with the clinical course because of a decrease in Leu 2a + cells. The pathogenesis of NEL is uncertain, but it has been speculated that there is cytolytic infection of lymphocytes by a virus or other organism, accompanied by secondary blastic transformation of suppressor T-lymphocytes.

High incidence of 17p13 chromosomal abnormalities in malignant histiocytosis

Cytogenetic analyses of three patients during autopsy who had a pathologic diagnosis of malignant histiocytosis and of one patient who was strongly suspected to have malignant histiocytosis because of her clinical and hematologic findings were done. All three patients studied with bone marrow specimens showed polyploidy (3.4-20%). Two of three patients with chromosomal abnormalities showed 17p+ markers with a breakpoint at 17p13. Seven of 22 previously reported malignant histiocytosis patients (32%) with descriptions of detailed whole karyotypes have the 17p+ markers, including two of the authors' patients. Five of seven patients with 17p+ involved 17p13. Although breakpoints at the 17p+ in the remaining two were not described, their karyotypes were shown to possibly involve 17p13. The high incidence of this abnormality is not considered accidental, and this breakpoint is not usual in many other neoplastic disorders. These facts may indicate that 17p13 chromosome abnormality is a specific change of malignant histiocytosis.

Neonatal brain abscess with intracystic hemorrhage--case report

The authors describe the case of an 11-day-old boy with high fever and signs of meningeal irritation in whom computed tomography demonstrated a large brain abscess with intracystic hemorrhage in the right temporal lobe. Cerebrospinal fluid analysis indicated purulent meningitis caused by Escherichia coli. After aspiration of the abscess contents, the entire ventricular system gradually enlarged. Despite repeated ventricular drainage and ventriculoperitoneal shunting, the lateral horn of the left lateral ventricle remained dilated. The isolation of the lateral ventricle may have resulted from septation due to the inflammatory reaction. This fluid was also shunted to the peritoneal cavity.

Inhibitory factor of actomyosin ATPase in the cardiac conduction system

ATPase activation and superprecipitation of natural actomyosin in the cardiac conduction system (specialized myocardium) and ventricle were compared. The ATPase activity and superprecipitation of natural actomyosin from the specialized myocardium were much lower than those from the ventricle. The sensitivity of natural actomyosin ATPase to calcium was higher in the specialized myocardium than in the ventricle, whereas the maximum activity of the specialized myocardium was lower than that of the ventricle. The Ca2+-desensitized actomyosin of the specialized myocardium presented scarcely any superprecipitation. Addition of the 0-40% ammonium sulfate fraction (mainly containing myosin and actin) of natural actomyosin from the specialized myocardium to ventricular natural actomyosin inhibited superprecipitation of the latter. On the other hand, addition of the 40-60% ammonium sulfate fraction (mainly containing troponins and tropomyosin) of natural actomyosin from the specialized myocardium enhanced superprecipitation of ventricular natural actomyosin. These results suggested that the specialized myocardium contains some factor(s) that inhibits actin-myosin interaction.

Distribution and metabolism of norepinephrine, cyclic AMP and cyclic GMP in the atrioventricular conducting tissue of the bovine heart

The distribution of norepinephrine (NE), cyclic AMP (cAMP) and cyclic GMP (cGMP) and the activities of related enzymes in the atrioventricular (A-V) conducting tissue of the bovine heart were examined. The concentration of NE in the atrium was about twice that in the ventricle. In the A-V conducting tissue, the concentration of NE was highest in the atrioventricular node (AVN) and lowest in the false tendon (FT), with intermediate levels in the bundle of His (HIS) and the right and left bundle branches (RLBB). The activity of monoamine oxidase (MAO) in the atrium was about 2.2 times that in the ventricle. In the A-V conducting tissue, the activity of MAO was highest in the HIS and lowest in the FT. The activity of catechol-o-methyltransferase (COMT) in the atrium and ventricle was similar, and that in the HIS was slightly, but not significantly, higher than that in other regions of the A-V conducting tissue. The concentration of cAMP in the ventricle was about twice that in the atrium. In the A-V conducting tissue, the concentration of cAMP was higher in the AVN and FT than in the HIS and RLBB. The distribution of adenylate cyclase (AC) was similar to that of NE. The phosphodiesterase (PDE) activity in the atrium and ventricle was similar. No significant difference was found in the level of PDE activity in different regions of the A-V conducting tissue. The concentration of cGMP was slightly, but not significantly, higher in the A-V conducting tissue than in the atrium or ventricle. In the A-V conducting tissue, the concentration of cGMP was highest in the FT and the concentrations in the HIS, RLBB and AVN were similar. These findings suggest that in the A-V conduction tissue, the regions that have the higher spontaneous pacemaker rates have higher NE content and AC activity, that is sensitivity to NE. Furthermore, the sensitivity for muscarinic cholinergic stimulation is higher in the conducting tissue (especially in the FT) than in the atrium and ventricle.

Pharmacokinetic studies on 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077). I. Blood and tissue concentrations of a new nitrosourea antitumor agent TA-077 and its metabolite TA-G after intravenous injection of TA-077 in various experimental animals

1-(2-Chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077) is a new masked antitumor agent, which is hydrolyzed by maltase to give rise to a more cell-permeable and, hence, more cytotoxic metabolite, TA-G. TA-077 was intravenously administered to mice, rats, guinea pigs, rabbits and dogs and the time-courses of blood concentrations of TA-077 and TA-G were followed. The time-course patterns of blood TA-077 in these animals were markedly different from one another depending on the level of plasma maltase, while those of blood TA-G were all similar except in the early stage after the injection; i.e., the blood concentration of TA-G reached a peak shortly after the injection and decreased rapidly with a half-life of 6 to 15 min, and the higher the level of plasma maltase, the earlier the time of peak appearance. Tissue concentrations of TA-077 and TA-G in major organs were also measured at various times after intravenous injection of TA-077 to guinea pigs and VX-2 tumor-bearing rabbits. In both species, tissue concentrations of TA-077 did not exceed the blood concentration and rapidly decreased to insignificant levels by 30 to 45 min. The tissue level of TA-G in the kidney, a maltase-rich organ, was always the highest among the organs examined in both species. The concentration of TA-G in the VX-2 tumor was relatively high. Possible significance of tissue maltase to the cellular uptake and antitumor effect of TA-077 is also discussed.

Necrotizing lymphadenitis. Electron microscopical and immunohistochemical study

Seven cases of necrotizing lymphadenitis (NEL) including a pair of male siblings, a female suffering from non-bacterial meningitis, and two cases with the proliferation of monocytes and/or macrophages in the bone marrow are reported. This disease is clinically documented by the occurrence in young adults usually accompanied by painful cervical lymphadenopathy with fever and leukopenia (below 4,000/mm3). Morphological features were characterized by nuclear debris from degenerated lymphocytes and the appearance of blastoid cells and/or immunoblasts and macrophages. Ultrastructurally, tubular inclusions with a close relation to the endoplasmic reticulum were observed in various kinds of cells in the lesion. Immunohistochemical studies revealed that the ratio of helper/suppressor T-lymphocytes became low at the active stage and returned to normal range at the recovery stage. By immuno-histochemical study it was confirmed that suppressor cells mainly corresponded to large transformed lymphocytes and/or immunoblasts and helper cells were degenerated by an unknown agent. Though the pathogenesis of NEL is still uncertain, it is suggested that T-lymphocytes are mainly involved during the course of the disease and lymphocytes show cellular debris or blastoid transformation.

Effect of 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea on experimental tumors

The antitumor activity of 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077), a novel water-soluble nitrosourea derivative, against leukemia L1210, Ehrlich carcinoma, sarcoma 180, Lewis lung carcinoma, Yoshida sarcoma, rat ascites hepatomas and Walker 256 carcinosarcoma was examined and compared with those of 3 reference nitrosourea antitumor agents, 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea, 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitrosourea hydrochloride and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. TA-077 exhibited a broad antitumor spectrum against the above tumors. Among these 4 nitrosoureas, TA-077 produced the best therapeutic ratios (OD/ILS30) against leukemia L1210, irrespective of the administration route and schedule employed. The ratio obtained by consecutive treatment (ip) was superior to that by single administration, a unique characteristic of this novel nitrosourea agent. The inhibitory effect of TA-077 on the growth of non-syngenic tumors (solid form) was also significant in all administration routes employed (ip, iv and po). Furthermore, TA-077 showed a marked life-prolonging effect on both early and advanced forms of Lewis lung carcinoma.

A new class of nitrosoureas. 4. Synthesis and antitumor activity of disaccharide derivatives of 3,3-disubstituted 1-(2-chloroethyl)-1-nitrosoureas

A series of 33 N-(2-chloroethyl)-N-nitrosocarbamoyl derivatives of N-substituted glycosylamines has been prepared and tested for antitumor activities. The compounds were obtained by reaction of glycosylamines with isocyanate, followed by nitrosation with N2O4. Structure-activity relationships of these trisubstituted nitrosoureas were investigated by varying the N-substituents and disaccharide groups and by comparing them with the corresponding disubstituted analogues. A large number of the nitrosoureas bearing a maltosyl group exhibited strong antitumor activities against leukemia L1210 and Ehrlich ascites carcinoma, and 60-day survivors against leukemia L1210 were found at the optimal dose for these derivatives. In contrast, the lactosyl and the melibiosyl derivatives were almost inactive. The most interesting compound in this series, the 3-isobutyl-3-maltosyl derivative (37), was tested against leukemia L1210 by single and multiple treatment. Its therapeutic ratio (96.3) obtained by multiple treatment is 3 times larger than that (31.5) obtained by single treatment, suggesting a possible clinical utility of 37 by multiple treatment. The favorable effect of a maltosyl moiety in this class of compounds is discussed.