Transcription of MERVL retrotransposons is required for preimplantation embryo development

Zygotic genome activation (ZGA) is a critical postfertilization step that promotes totipotency and allows different cell fates to emerge in the developing embryo. MERVL (murine endogenous retrovirus-L) is transiently upregulated at the two-cell stage during ZGA. Although MERVL expression is widely used as a marker of totipotency, the role of this retrotransposon in mouse embryogenesis remains elusive. Here, we show that full-length MERVL transcripts, but not encoded retroviral proteins, are essential for accurate regulation of the host transcriptome and chromatin state during preimplantation development. Both knockdown and CRISPRi-based repression of MERVL result in embryonic lethality due to defects in differentiation and genomic stability. Furthermore, transcriptome and epigenome analysis revealed that loss of MERVL transcripts led to retention of an accessible chromatin state at, and aberrant expression of, a subset of two-cell-specific genes. Taken together, our results suggest a model in which an endogenous retrovirus plays a key role in regulating host cell fate potential.

Memory B Cells and Memory T Cells Induced by SARS-CoV-2 Booster Vaccination or Infection Show Different Dynamics and Responsiveness to the Omicron Variant

Although the immunological memory produced by BNT162b2 vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been well studied and established, further information using different racial cohorts is necessary to understand the overall immunological response to vaccination. We evaluated memory B and T cell responses to the severe acute respiratory syndrome coronavirus 2 spike protein before and after the third booster using a Japanese cohort. Although the Ab titer against the spike receptor-binding domain (RBD) decreased significantly 8 mo after the second vaccination, the number of memory B cells continued to increase, whereas the number of memory T cells decreased slowly. Memory B and T cells from unvaccinated infected patients showed similar kinetics. After the third vaccination, the Ab titer increased to the level of the second vaccination, and memory B cells increased at significantly higher levels before the booster, whereas memory T cells recovered close to the second vaccination levels. In memory T cells, the frequency of CXCR5+CXCR3+CCR6- circulating follicular Th1 was positively correlated with RBD-specific Ab-secreting B cells. For the response to variant RBDs, although 60-80% of memory B cells could bind to the omicron RBD, their avidity was low, whereas memory T cells show an equal response to the omicron spike. Thus, the persistent presence of memory B and T cells will quickly upregulate Ab production and T cell responses after omicron strain infection, which prevents severe illness and death due to coronavirus disease 2019.

TDP-43 safeguards the embryo genome from L1 retrotransposition

Transposable elements (TEs) are genomic parasites that propagate within the host genome and introduce mutations. Long interspersed nuclear element-1 (LINE-1 or L1) is the major TE class, which occupies nearly 20% of the mouse genome. L1 is highly active in mammalian preimplantation embryos, posing a major threat to genome integrity, but the mechanism of stage-specific protection against L1 retrotransposition is unknown. Here, we show that TAR DNA-binding protein 43 (TDP-43), mutations in which constitute a major risk factor for amyotrophic lateral sclerosis, inhibits L1 retrotransposition in mouse embryonic stem cells (mESCs) and preimplantation embryos. Knockdown of TDP-43 resulted in massive genomic L1 expansion and impaired cell growth in preimplantation embryos and ESCs. Functional analysis demonstrated that TDP-43 interacts with L1 open reading frame 1 protein (L1 ORF1p) to mediate genomic protection, and loss of this interaction led to derepression of L1 retrotransposition. Our results identify TDP-43 as a guardian of the embryonic genome.

Generation of Stable Drosophila Ovarian Somatic Cell Lines Using the piggyBac System

Transposable elements (TEs) constitute a large proportion of the genome in multiple organisms. Therefore, anti-transposable element machineries are essential to maintain genomic integrity. PIWI-interacting RNAs (piRNAs) are a major force to repress TEs in Drosophila ovaries. Ovarian somatic cells (OSC), in which nuclear piRNA regulation is functional, have been used for research on piRNA pathway as a cell culture system to elucidate the molecular mechanisms underlying the piRNA pathway. Analysis of piRNA pathway using a reporter system to monitor the gene regulation or overexpression of specific genes would be a powerful approach. Here, we present the technical protocol to establish stable cell lines using the piggyBac system, adopted for OSCs. This easy, consistent, and timesaving protocol may accelerate research on the piRNA pathway.

The emergence of SARS-CoV-2 variants threatens to decrease the efficacy of neutralizing antibodies and vaccines

The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the coronavirus disease (COVID-19) pandemic. As of August 2021, more than 200 million people have been infected with the virus and 4.3 million have lost their lives. Various monoclonal antibodies of human origin that neutralize the SARS-CoV-2 infection have been isolated from convalescent patients for therapeutic and prophylactic purposes. Several vaccines have been developed to restrict the spread of the virus and have been rapidly administered. However, the rollout of vaccines has coincided with the spread of variants of concern. Emerging variants of SARS-CoV-2 present new challenges for therapeutic antibodies and threaten the efficacy of current vaccines. Here, we review the problems faced by neutralizing antibodies and vaccines in the midst of the increasing spread of mutant viruses.

Potent mouse monoclonal antibodies that block SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has developed into a global pandemic since its first outbreak in the winter of 2019. An extensive investigation of SARS-CoV-2 is critical for disease control. Various recombinant monoclonal antibodies of human origin that neutralize SARS-CoV-2 infection have been isolated from convalescent patients and will be applied as therapies and prophylaxis. However, the need for dedicated monoclonal antibodies suitable for molecular pathology research is not fully addressed. Here, we produced six mouse anti-SARS-CoV-2 spike monoclonal antibodies that not only exhibit robust performance in immunoassays including western blotting, ELISA, immunofluorescence, and immunoprecipitation, but also demonstrate neutralizing activity against SARS-CoV-2 infection to VeroE6/TMPRSS2 cells. Due to their mouse origin, our monoclonal antibodies are compatible with the experimental immunoassay setups commonly used in basic molecular biology research laboratories, providing a useful tool for future research. Furthermore, in the hope of applying the antibodies of clinical setting, we determined the variable regions of the antibodies and used them to produce recombinant human/mouse chimeric antibodies.

Piwi suppresses transcription of Brahma-dependent transposons via Maelstrom in ovarian somatic cells

Drosophila Piwi associates with PIWI-interacting RNAs (piRNAs) and represses transposons transcriptionally through heterochromatinization; however, this process is poorly understood. Here, we identify Brahma (Brm), the core adenosine triphosphatase of the SWI/SNF chromatin remodeling complex, as a new Piwi interactor, and show Brm involvement in activating transcription of Piwi-targeted transposons before silencing. Bioinformatic analyses indicated that Piwi, once bound to target RNAs, reduced the occupancies of SWI/SNF and RNA polymerase II (Pol II) on target loci, abrogating transcription. Artificial piRNA-driven targeting of Piwi to RNA transcripts enhanced repression of Brm-dependent reporters compared with Brm-independent reporters. This was dependent on Piwi cofactors, Gtsf1/Asterix (Gtsf1), Panoramix/Silencio (Panx), and Maelstrom (Mael), but not Eggless/dSetdb (Egg)-mediated H3K9me3 deposition. The λN-box B-mediated tethering of Mael to reporters repressed Brm-dependent genes in the absence of Piwi, Panx, and Gtsf1. We propose that Piwi, via Mael, can rapidly suppress transcription of Brm-dependent genes to facilitate heterochromatin formation.

Essential roles of Windei and nuclear monoubiquitination of Eggless/SETDB1 in transposon silencing

Eggless/SETDB1 (Egg), the only essential histone methyltransferase (HMT) in Drosophila, plays a role in gene repression, including piRNA-mediated transposon silencing in the ovaries. Previous studies suggested that Egg is post-translationally modified and showed that Windei (Wde) regulates Egg nuclear localization through protein-protein interaction. Monoubiquitination of mammalian SETDB1 is necessary for the HMT activity. Here, using cultured ovarian somatic cells, we show that Egg is monoubiquitinated and phosphorylated but that only monoubiquitination is required for piRNA-mediated transposon repression. Egg monoubiquitination occurs in the nucleus. Egg has its own nuclear localization signal, and the nuclear import of Egg is Wde-independent. Wde recruits Egg to the chromatin at target gene silencing loci, but their interaction is monoubiquitin-independent. The abundance of nuclear Egg is governed by that of nuclear Wde. These results illuminate essential roles of nuclear monoubiquitination of Egg and the role of Wde in piRNA-mediated transposon repression.

Nuclear RNA export factor variant initiates piRNA-guided co-transcriptional silencing

The PIWI-interacting RNA (piRNA) pathway preserves genomic integrity by repressing transposable elements (TEs) in animal germ cells. Among PIWI-clade proteins in Drosophila, Piwi transcriptionally silences its targets through interactions with cofactors, including Panoramix (Panx) and forms heterochromatin characterized by H3K9me3 and H1. Here, we identified Nxf2, a nuclear RNA export factor (NXF) variant, as a protein that forms complexes with Piwi, Panx, and p15. Panx-Nxf2-P15 complex formation is necessary in the silencing by stabilizing protein levels of Nxf2 and Panx. Notably, ectopic targeting of Nxf2 initiates co-transcriptional repression of the target reporter in a manner independent of H3K9me3 marks or H1. However, continuous silencing requires HP1a and H1. In addition, Nxf2 directly interacts with target TE transcripts in a Piwi-dependent manner. These findings suggest a model in which the Panx-Nxf2-P15 complex enforces the association of Piwi with target transcripts to trigger co-transcriptional repression, prior to heterochromatin formation in the nuclear piRNA pathway. Our results provide an unexpected connection between an NXF variant and small RNA-mediated co-transcriptional silencing.

Tbx6 Induces Nascent Mesoderm from Pluripotent Stem Cells and Temporally Controls Cardiac versus Somite Lineage Diversification

The mesoderm arises from pluripotent epiblasts and differentiates into multiple lineages; however, the underlying molecular mechanisms are unclear. Tbx6 is enriched in the paraxial mesoderm and is implicated in somite formation, but its function in other mesoderms remains elusive. Here, using direct reprogramming-based screening, single-cell RNA-seq in mouse embryos, and directed cardiac differentiation in pluripotent stem cells (PSCs), we demonstrated that Tbx6 induces nascent mesoderm from PSCs and determines cardiovascular and somite lineage specification via its temporal expression. Tbx6 knockout in mouse PSCs using CRISPR/Cas9 technology inhibited mesoderm and cardiovascular differentiation, whereas transient Tbx6 expression induced mesoderm and cardiovascular specification from mouse and human PSCs via direct upregulation of Mesp1, repression of Sox2, and activation of BMP/Nodal/Wnt signaling. Notably, prolonged Tbx6 expression suppressed cardiac differentiation and induced somite lineages, including skeletal muscle and chondrocytes. Thus, Tbx6 is critical for mesoderm induction and subsequent lineage diversification.

Mitotic phosphorylation of CCCTC-binding factor (CTCF) reduces its DNA binding activity

During mitosis, higher order chromatin structures are disrupted and chromosomes are condensed to achieve accurate chromosome segregation. CCCTC‐binding factor (CTCF) is a highly conserved and ubiquitously expressed C2H2‐type zinc finger protein which is considered to be involved in epigenetic memory through regulation of higher order chromatin architecture. However, the regulatory mechanism of CTCF in mitosis is still unclear. Here we found that the DNA‐binding activity of CTCF is regulated in a phosphorylation‐dependent manner during mitosis. The linker domains of the CTCF zinc finger domain were found to be phosphorylated during mitosis. The phosphorylation of linker domains impaired the DNA‐binding activity in vitro. Mutation analyses showed that amino acid residues (Thr289, Thr317, Thr346, Thr374, Ser402, Ser461, and Thr518) located in the linker domains were phosphorylated during mitosis. Based on these results, we propose that the mitotic phosphorylation of the linker domains of CTCF is important for the dissociation of CTCF from mitotic chromatin.

Piwi Modulates Chromatin Accessibility by Regulating Multiple Factors Including Histone H1 to Repress Transposons

PIWI-interacting RNAs (piRNAs) mediate transcriptional and post-transcriptional silencing of transposable element (TE) in animal gonads. In Drosophila ovaries, Piwi-piRNA complexes (Piwi-piRISCs) repress TE transcription by modifying the chromatin state, such as by H3K9 trimethylation. Here, we demonstrate that Piwi physically interacts with linker histone H1. Depletion of Piwi decreases H1 density at a subset of TEs, leading to their derepression. Silencing at these loci separately requires H1 and H3K9me3 and heterochromatin protein 1a (HP1a). Loss of H1 increases target loci chromatin accessibility without affecting H3K9me3 density at these loci, while loss of HP1a does not impact H1 density. Thus, Piwi-piRISCs require both H1 and HP1a to repress TEs, and the silencing is correlated with the chromatin state rather than H3K9me3 marks. These findings suggest that Piwi-piRISCs regulate the interaction of chromatin components with target loci to maintain silencing of TEs through the modulation of chromatin accessibility.

Oseltamivir expands quasispecies of influenza virus through cell-to-cell transmission

The population of influenza virus consists of a huge variety of variants, called quasispecies, due to error-prone replication. Previously, we reported that progeny virions of influenza virus become infected to adjacent cells via cell-to-cell transmission pathway in the presence of oseltamivir. During cell-to-cell transmission, viruses become infected to adjacent cells at high multiplicity since progeny virions are enriched on plasma membrane between infected cells and their adjacent cells. Co-infection with viral variants may rescue recessive mutations with each other. Thus, it is assumed that the cell-to-cell transmission causes expansion of virus quasispecies. Here, we have demonstrated that temperature-sensitive mutations remain in progeny viruses even at non-permissive temperature by co-infection in the presence of oseltamivir. This is possibly due to a multiplex infection through the cell-to-cell transmission by the addition of oseltamivir. Further, by the addition of oseltamivir, the number of missense mutation introduced by error-prone replication in segment 8 encoding NS1 was increased in a passage-dependent manner. The number of missense mutation in segment 5 encoding NP was not changed significantly, whereas silent mutation was increased. Taken together, we propose that oseltamivir expands influenza virus quasispecies via cell-to-cell transmission, and may facilitate the viral evolution and adaptation.

Reconstitution of human rRNA gene transcription in mouse cells by a complete SL1 complex

An important characteristic of the transcription of a ribosomal RNA gene (rDNA) mediated by DNA-dependent RNA polymerase (Pol) I is its stringent species specificity. SL1/TIF-IB is a key complex for species specificity, but its functional complex has not been reconstituted. Here, we established a novel and highly sensitive monitoring system for Pol I transcription to reconstitute the SL1 activity in which a transcript harboring a reporter gene synthesized by Pol I is amplified and converted into translatable mRNA by the influenza virus RNA-dependent RNA polymerase. Using this monitoring system, we reconstituted Pol I transcription from the human rDNA promoter in mouse cells by expressing four human TATA-binding protein (TBP)-associated factors (TAFIs) in the SL1 complex. The reconstituted SL1 also re-activated human rDNA transcription in mouse A9 cells carrying an inactive human chromosome 21 that contains the rDNA cluster. Chimeric SL1 complexes containing human and mouse TAFIs could be formed, but these complexes were inactive for human rDNA transcription. We conclude that four human TAFIs are necessary and sufficient to overcome the barrier of species specificity for human rDNA transcription in mouse cells.

Development of a highly efficient implanted thermal ablation device: in vivo experiment in rat liver

OBJECTIVES

To evaluate an implanted thermal ablation device that can be heated with high efficiency using a resonant circuit as the implant.

METHODS

16 rats were used. The implants, adjusted at a resonance frequency of 4 MHz, were fixed on the surface of the liver of rats under laparotomy. In 14 of 16 rats, an alternating magnetic field (AMF) was applied for 6 min with an output of 300 W from outside the body using a ferrite core applicator. The implant temperature during AMF exposure was measured. The 14 rats were divided into 5 groups, depending on time from AMF application until they were sacrificed (1 h, 1 day, 3 days, 7 days and 1 month after application). Two rats not exposed to AMF were used as controls. Livers were removed and evaluated; the cross-sectional area and width of the ablated region were measured.

RESULTS

During AMF exposure, the implant temperature rose to 127.8±39.3 °C (mean±standard deviation). The cross-sectional area of the ablated region was largest after 1 day and tended to decrease with time. The widths of the ablated region were 4.87±0.22 mm, 4.15±0.36 mm, 3.67±0.58 mm and 3.24±0.16 mm in the 1 day, 3 day, 7 day and 1 month groups, respectively. No significant differences (p<0.05) were seen in either cross-sectional area or width of the ablated region.

CONCLUSION

Sufficient heat for ablation was obtained in vivo using a newly developed implanted thermal ablation device. This device may be a new option for thermal ablation therapy.

Sp1-mediated transcription regulation of TAF-Ialpha gene encoding a histone chaperone

TAF-I, one of histone chaperones, consists of two subtypes, TAF-Ialpha and TAF-Ibeta. The histone chaperone activity of TAF-I is regulated by dimer patterns of these subtypes. TAF-Ibeta is expressed ubiquitously, while the expression level of TAF-Ialpha with less activity than TAF-Ibeta differs among cell types. It is, therefore, assumed that the expression level of TAF-Ialpha in a cell is important for the TAF-I activity level. Here, we found that TAF-Ialpha and TAF-Ibeta genes are under the control of distinct promoters. Reporter assays and gel shift assays demonstrated that Sp1 binds to three regions in the TAF-Ialpha promoter and two or all mutaions of the three Sp1 binding regions reduced the TAF-Ialpha promoter activity. ChIP assays demonstrated that Sp1 binds to the TAF-Ialpha promoter in vivo. Furthermore, the expression level of TAF-Ialpha mRNA was reduced by knockdown of Sp1 using siRNA method. These studies indicated that the TAF-Ialpha promoter is under the control of Sp1.

Effect of antenatal dexamethasone treatment on Ca2+-dependent nitric oxide synthase activity in rat lung

We investigated the effects of dexamethasone on nitric oxide synthase activity, nitrate/nitrite concentration, and cGMP concentration in the lungs of premature and full-term neonate rats. Dexamethasone or vehicle alone was administered to the mother (1 mg/kg/d, s.c., 2 d), and the neonate was killed 24 h after birth. Ca2+-dependent nitric oxide synthase activity and nitrate/nitrite and cGMP concentrations in lungs of dexamethasone-treated neonates, both premature and full-term, were significantly higher than those in the lungs of the control rats. Ca2+-dependent nitric oxide synthase activity, nitrate/nitrite concentration, and cGMP concentration in the lungs of control rats showed developmentally associated increases during late gestation and in the early postnatal period. The activation of the nitric oxide synthasenitric oxide-cGMP system by antenatal dexamethasone treatment may be related to the improvement of pulmonary function by antenatal glucocorticoid therapy to minimize respiratory distress syndrome.

Conformational studies on the four stereoisomers of the novel anticholinergic 4-(dimethylamino)-2-phenyl-2-(2-pyridyl)pentanamide

To interpret differences in the anticholinergic activity among the four stereoisomers of 4-(dimethylamino)-2-phenyl-2-(2-pyridyl)pentanamide (1-4), we performed conformational studies using the semiempirical molecular orbital method. The structures of the global minimum-energy conformations obtained for 1-4, however, could not explain the different activities, particularly in terms of distances between the essential pharmacophores. We thus implemented superimposition studies, using the energetically stable conformations of the most active stereoisomer, 1(2S,4R), as a template. The energy penalties for a conformation change of the less active stereoisomers 2-4 from their global minimum-energy structure to a new conformation, fitting onto the global minimum-energy conformation of 1, appear to account for the differences in the pharmacological potency better than using the other conformations of 1 as a template. We thus presume that the global minimum-energy conformation of 1 is closely related to the bioactive conformation for these anticholinergics, and also that the pharmacological potency is linked to how readily these substances can change their conformations to fit the muscarinic receptor.

[Myocardial imaging with 123I-metaiodobenzylguanidine (123I-MIBG) in essential hypertension: does the 123I-MIBG imaging have the ability to predict its prognosis?]

To study myocardial norepinephrine (NE) activity in essential Hypertension 9HT) and to clarify its prognostic significance, we performed myocardial imaging with 123I-metaiodobenzylguanidine (123I-MIBG) and 201Tl at rest in 16 patients with HT and 9 normal subjects. In addition to ordinary tomograms, whole body images were obtained in both 123I-MIBG and 201Tl imaging. From the whole body image, a ratio of myocardial radionuclide accumulation to total injected dose was calculated (%Uptake). And Uptake Ratio (%Uptake of 123I-MIBG/%Uptake of 201Tl) was used as an index of myocardial 123I-MIBG uptake. Reduction of myocardial 123I-MIBG during 3 hours was calculated and expressed as washout rate (WOR). From the Bull's-eye map, the extent of defect was quantitatively assessed (Defect Score) and the homogeneity of the radionuclide distribution within the myocardium (CV) was calculated. In 123I-MIBG imaging, defect appeared in 12 patients with HT (75%), but in normal subject no one showed defect. Patients with HT were divided into two groups according to left ventricular ejection fraction (EF) responses to exercise stress which were obtained by 99mTc blood pool imaging. Group 1 consisted of 8 patients who showed EF elevation (5-10%) by exercise and group 2 consisted of 6 patients with depression of EF (-4-6%) by exercise. Rest EF, peak filling rate, exercise heart rate, exercise blood pressure and left ventricular mass were identical between two groups. Uptake Ratio in Group 2 (0.67 +/- 0.04) was significantly smaller (p < 0.05) than those in Group 1 (0.75 +/- 0.05) and normal subject (0.75 +/- 0.06). And in Group 2, WOR of 123I-MIBG was greater than that of Group 1. In Group 2, defect of 123I-MIBG appeared in all patients, but in Group 1 defect developed in 50%, besides Defect Score was significantly greater in Group 2 than in Group 1 (3.8 +/- 1.4 vs. 1.5 +/- 1.8, p < 0.05). The unhomogeneity of 123I-MIBG distribution was significantly greater in Group 2 (CV; 30 +/- 5%) than in Group 1 (21 +/- 4%) and in normal subjects (18 +/- 4%). These results suggested that quantitative analysis of 123I-MIBG imaging may be helpful for assessing the prognosis of HT.

[Quantitative analysis of 123I-metaiodobenzylguanidine myocardial imaging: assessment of its usefulness in patients with congestive heart failure]

To investigate the usefulness of the quantitative analysis of 123I-metaiodobenzylguanidine (123I-MIBG) myocardial uptake, we studied 9 normal subjects and 18 patients with congestive heart failure (CHF). Rest myocardial imaging with 123I-MIBG was performed at 20 minutes and 3 hours (delayed image) after 123I-MIBG injection. Rest 201Tl imaging was obtained at 20 minutes after 201Tl injection. In addition to ordinary tomograms, a planar anterior image and a whole body image were supplemented in each imaging. In patients with CHF fractional shortening (%FS) was calculated from echocardiography and left ventricular ejection fraction was obtained from cardiac blood pool imaging with 99mTc at rest. We calculated H/M (heart to mediastinum count ratio) from the anterior planar image and %Uptake (percentage of cardiac uptake of the isotope to total injected dose) from the whole body image. H/M of 123I-MIBG in delayed images separated patients with CHF from normal subjects (2.00 +/- 0.19 vs. 2.56 +/- 0.13, p < 0.01). H/M Ratio (H/M of 123I-MIBG divided by H/M of 201Tl) in delayed image could distinguish these two groups poorly (0.72 +/- 0.12 vs. 0.88 +/- 0.14, p < 0.05). On the other hand, %Uptake of 123I-MIBG was not different between two groups (3.49 +/- 0.60% in CHF, 3.54 +/- 0.34% in normal). But %Uptake of 201Tl was greater in CHF than in normal (5.96 +/- 1.09% vs. 4.70 +/- 0.30%, p < 0.05). When myocardial 123I-MIBG uptake was normalized by myocardial perfusion (%Uptake of 123I-MIBG divided by %Uptake of 201Tl, Uptake Ratio), Uptake Ratio in delayed image could distinguish theses two groups as same as H/M (0.60 +/- 0.05 in CHF, 0.75 +/- 0.05 in normal, p < 0.01). In patients with CHF, H/M of 123I-MIBG did not reflect LV function and serum norepinephrine (NE) level. But Uptake Ratio and H/M Ratio in delayed image correlated well with %FS (r = 0.88, r = 0.65), EF (r = 0.80, r = 0.68) and NE level (r = -0.77, r = -0.75). Although the calculation of Uptake Ratio is time consuming and expensive, it was assumed that Uptake Ratio is an useful index to quantitate myocardial 123I-MIBG uptake.

CS-045, a new oral antidiabetic agent, stimulates fructose-2,6-bisphosphate production in rat hepatocytes

Fructose-2,6-bisphosphate is a potent activator of 6-phosphofructo-1-kinase, a key enzyme in glycolysis. We previously revealed that sulfonylureas stimulate fructose-2,6-bisphosphate production in the rat liver by activating 6-phosphofructo-2-kinase. In the present study, we show that CS-045, a new antidiabetic agent, activated 6-phosphofructo-2-kinase and raised fructose-2,6-bisphosphate levels in dispersed rat hepatocytes. This action was time- and dose-dependent. Ten micromolar CS-045 raised the fructose-2,6-bisphosphate content linearly to the submaximal level in 20 min. Dose dependency was observed in the range of 1-30 microM. Thirty micromolar CS-045 completely reversed the inhibitory effect of 0.1 nM glucagon on fructose-2,6-bisphosphate production. CS-045 activated 6-phosphofructo-2-kinase by decreasing the Km value for the substrate (fructose-6-phosphate) without affecting the Vmax. The combination of suboptimal doses of CS-045 and tolbutamide increased fructose-2,6-bisphosphate content more than that induced by each agent alone. These results indicate that CS-045 may reduce plasma glucose by facilitating glycolysis in the liver.

[Assessment of myocardial viability by exercise stress-redistribution myocardial scintigraphy with thallium-201: the usefulness of C-map]

Standard exercise (Ex)-redistribution (RD) myocardial imaging with thallium-201 (201Tl) may not differentiate viable myocardium from necrosis. This study was intended to clarify whether 201Tl washout rate (WOR) abnormality after Ex can detect myocardial viability in the myocardium with perfusion defect using routine RD image. We performed Ex-RD (three hours after) myocardial tomography with 201Tl in 29 patients with coronary artery disease. From myocardial tomography, 201Tl distribution Bull's-eye maps (Ex and RD) and WOR Bull's-eye map were made. At RD image before PTCA, by referring to the original image, the activity of the myocardial region below 40% to 55% of the maximal 201Tl activity was considered as perfusion defect (RD-Map). Then we constructed a new image (C-Map) by adding the location of WOR abnormality (< or = 30%) to the RD-Map and each map was divided into 17 segments. If the defect-segment in the RD-Map corresponded to WOR abnormality, the segment in the C-Map was judged as viable (no defect). The C-Map and myocardial imaging after PTCA (Post-Map) were compared. In the RD-Map before PTCA, defect was found in 152 segments but in the C-Map they decreased to 59 segments, while defect was found in 62 segments in the Post-Map. In 23 patients the number of defect-segments in the C-Map decreased as compared with those in the RD-Map. And in 22 of them, the Post-Map showed the reduction of defect-segments in comparison with the RD-Map, but in one of them defect did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on neurokinin antagonists. 3. Design and structure-activity relationships of new branched tripeptides N alpha-(substituted L-aspartyl, L-ornithyl, or L-lysyl)-N-methyl-N-(phenylmethyl)-L-phenylalaninamides as substance P antagonists

As an extension of our study on discovering a novel substance P (SP) antagonist, we designed new branched tripeptides containing L-aspartic acid (2 and 5), L-ornithine (3 and 6), and L-lysine (4 and 7) by reconstructing the structure of the previously reported tripeptide SP antagonist [Ac-Thr-D-Trp(CHO)-Phe-NMeBzl (1), FR113680]. The strategy for this design was based on the postulate that the dipeptide half D-Trp(CHO)-Phe-NMeBzl in 1 is essential for receptor recognition. Molecular modeling studies implied that these newly designed tripeptides could mimic the spatial orientations of the essential dipeptide structure. As expected, all of these compounds potently inhibited 3H-SP (1 nM) binding to guinea pig lung membranes in the 10(-8) M range. The 1H-indol-3-ylcarbonyl derivatives (5-7) were slightly more potent than the corresponding 1H-indol-2-ylcarbonyl derivatives (2-4), as predicted by the molecular modeling studies. The structure-activity relationships studies on the selected 1H-indol-3-ylcarbonyl derivatives indicated that the threonine moiety at the side chain can be modified into a variety of structures without any significant loss of the activity. Furthermore in the L-lysine series, even dipeptide compounds having nothing or a simple acyl group at the epsilon-amino group, such as N alpha-[N alpha-(1H-indol-3-ylcarbonyl)-L-lysyl]-N-methyl-N-(phenylmethyl)- L-phenylalaninamide (18b), exhibited potent activity. These dipeptides belong to a new structural class of SP antagonist.

Distributions of the calcitonin gene-related peptide and substance P in the monkey larynx

The distribution of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivity in the monkey larynx was studied with light microscopy using the immunofluorescence method. We divided the larynx into the following six regions: epiglottis, arytenoid region, false cords, ventricle, vocal cords and subglottis. The distribution of immunoreactivity in the epithelium and subepithelial layer was determined. CGRP- and SP-like immunoreactive nerve fibers were observed in all regions of the laryngeal epithelium except in the vocal cords. In the epithelium of the epiglottis and arytenoid region, numerous taste buds containing several CGRP- and SP-like immunoreactive nerve fibers were observed. In the subepithelial layer, CRGP- and SP-like immunoreactive nerve fibers were observed in all regions of the larynx. In order of decreasing density, these fibers were found in the arytenoid region (especially the corniculate tubercle), the epiglottis, the false cords, the subglottis, the ventricle, and the vocal cords. In the corniculate tubercle, CGRP- and SP-like immunoreactive nerve fibers formed a network, whereas around the cuneiform tubercle, dense CRPG- and SP-like immunoreactive nerve fibers were noted parallel to the basement membrane. SP-like immunoreactive nerve fibers showed a very similar distribution to the CRPG fibers in the epithelium and the subepithelial layer, but SP-like fibers were sparser in all regions of the larynx. These results, together with previous findings indicate that the arytenoid region and the epiglottis of the monkey larynx play very important roles in airway protection, swallowing, and respiration.

[Myocardial perfusion in patients with left bundle branch block and without coronary artery disease]

For the evaluation of myocardial perfusion in patients with left bundle branch block (LBBB), we performed exercise stress (Ex)-redistribution (RD) myocardial tomography with thallium-201 (201Tl) in 23 patients with LBBB and without coronary artery disease (CAD). Myocardial images in patients with LBBB were compared with those of 9 patients with CAD who showed Ex induced transient septal defect. Bull'-eye maps (201Tl distribution maps at Ex and RD and 201Tl washout rate [WOR] map) were made from myocardial tomograms. In 23 patients with LBBB, 15 patients (65%) developed myocardial perfusion abnormality. In 10 (67%) of these 15 patients, transient perfusion defect appeared in the entire septum (diffuse type). On the other hand in 5 patients (33%), localized fixed perfusion defect developed at the boundary between septum and anterior wall (focal type). In focal type, every patient had other disease such as hypertension, aortic stenosis or sick sinus syndrome. While in patients with diffuse type, other diseases were observed in 30% (p less than 0.05) and they were limited to hypertension or diabetes mellitus. These facts suggested that mechanisms of perfusion abnormalities might be different between these two groups. We compared the perfusion abnormality between LBBB diffuse type and CAD. The extent of the defects was not different between two groups. Although apex was included within the defect in 89% of CAD population, apical defect was observed in only 20% of diffuse type (p less than 0.05). Minimal 201Tl WOR and 201Tl uptake ratio of septum to lateral wall indicated that exercise induced septal defect was slighter in diffuse type than CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of myocardial viability by exercise stress myocardial tomography with 201Tl--the usefulness of 201Tl washout rate]

Exercise stress (Ex) and redistribution (RD) myocardial tomography with thallium-201 (Tl-201) has been widely used for evaluating myocardial viability. But recent studies have demonstrated that reinjection (ReI) study following RD study is necessary for detecting reversible ischemic myocardium. On the other hand, decreased myocardial washout of Tl-201 after Ex is an indicator of myocardial ischemia. So we have studied the usefulness of myocardial Tl-201 washout rate (WOR) for the evaluation of myocardial viability by comparing it with ReI images. Ex and RD myocardial tomographies were obtained immediately after Ex and 3 hours later. After RD study a small amount of Tl-201 was injected and ReI imaging was repeated. We studied 64 myocardial segments (in 58 patients with coronary artery disease) in which Ex-induced perfusion defects persisted in RD images. According to the changes of perfusion defects between Ex, RD and ReI images, they were classified into 3 types: Type I; perfusion defect on the RD image was identical to ReI image (75%) Type I was divided into 2 subgroups whether perfusion defect at Ex was unchanged (Ia, 42%) or improved (Ib, 33%) on the RD image. Type II; perfusion defect at Ex was reduced on the RD image and it improved furthermore at ReI image (17%). Type III; perfusion defect was the same at Ex and RD but it was reduced on the ReI image (8%). WOR less than 30% was defined as abnormal when Ex heart rate exceeded 120 bpm and lung-myocardial Tl-201 uptake ratio was less than 0.45.(ABSTRACT TRUNCATED AT 250 WORDS)

[Usefulness of serum cardiac myosin light chain I for the estimation of acute myocardial infarction size]

To evaluate the usefulness of serum level of cardiac myosin light chain I (LC I) for the estimation of the extent of acute myocardial infarction (AMI), peak LC I level was compared with myocardial infarction weight (AMI weight) which was obtained by myocardial emission tomography with Tc-99m pyrophosphate (PYP). In 11 patients with AMI, serum LC I levels were measured once a day in most cases, and plasma CPK levels were measured serially (every 4 hours at least 48 hours after admission). Tc-99m PYP imagings were performed at second or third day of AMI, and AMI weight was calculated from the voxel numbers of myocardial hot spot in which Tc-99m PYP had accumulated. Peak LC I level correlated well with AMI weight (r = 0.72, p less than 0.02). As well as peak LC I level, peak CPK level correlated well with AMI weight (r = 0.68, p less than 0.05). But the estimation of the infarct size from peak LC I level had the following advantages over the estimation from peak CPK level. 1) We could compare peak LC I level with AMI weight in all 11 patients, but peak CPK level was able to compared with AMI weight in only 9 of them. This was because CPK level changed rapidly and reached maximum within 24 hours after the onset of AMI, while LC I level peaked after 3 to 5 days. 2) A good correlation between LC I and AMI weight was obtained by the determination of serum LC I level once a day.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical implications of diffuse slow washout of thallium-201 in exercise stress myocardial SPECT]

Clinical implications of diffuse slow washout of thallium-201 (DSWO) in exercise-redistribution myocardial SPECT were studied. Thallium-201 washout rate was calculated by Bull's-eye method. DSWO was defined as having abnormal thallium-201 washout rate (less than 30% per 3 hours) in more than two thirds of each coronary artery (CA) area. OF 974 patients whose exercise heart rate exceeded 120/min, 51 (5.2%) showed DSWO and coronary angiography was performed in 43. Twenty-three patients (53%) showed triple vessel disease (3VD), 8 (19%) showed single or double vessel disease (1VD/2VD) and 12 (28%) showed normal CA. Patients with normal CA consisted of 6 patients with hypertrophic cardiomyopathy (HCM), 5 with hypertension (HT) and one with electrocardiographic abnormality only. The causes of DSWO were assessed from the history of effort angina (EA) and congestive heart failure (CHF), delayed fill-in of the perfusion defect and the ratio of lung to heart thallium-201 activity (L/M) at exercise as an indicator of the left ventricular (LV) function. High prevalence of EA (74%), high incidence of scintigraphic delayed fill-in (83%) and normal L/M suggested diffuse LV ischemia as the cause of DSWO in 3VD. On the other hand in patients with 1VD/2VD, LV dysfunction at exercise was considered as the cause of DSWO because of low prevalence of EA (13%) and scintigraphic delayed fill-in (13%) (p less than 0.01, p less than 0.005 each vs 3VD), and high L/M (p less than 0.001 vs 3VD) and high prevalence of CHF (38%, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

[Myocardial perfusion abnormality and chest pain in patients with hypertrophic cardiomyopathy]

To investigate the role of myocardial ischemia in the development of chest pain in patients with hypertrophic cardiomyopathy (HCM), exercise stress (Ex) redistribution myocardial single photon emission CT's (SPECT's) with thallium-201 (Tl) were obtained in 27 patients with HCM. In all patients, coronary arteries were normal arteriographically. Patients were classified into NYHA Class I, II and III according to the frequency and severity of the chest pain during daily life. In these 3 groups, age, sex and intraventricular septal thickness measured by echocardiography were not different. Types of myocardial perfusion obtained by myocardial SPECT's were divided into 5: 1) normal perfusion, 2) no perfusion defect with abnormal myocardial Tl washout rate (WOR) during 3 hours (less than 30%) [Def(-)/WORabn], 3) reversible perfusion defect (RD), 4) fixed defect with abnormal WOR (FD/WORabn), 5) fixed defect with normal WOR (FD/WORnl). In 14 patients with Class I, 9 patients (64%) showed normal perfusion but the rest showed perfusion abnormality (def(-)/WORabn in 3 and RD in 2). In Class II and III, all patients showed perfusion abnormalities of RD, FD/WORabn or FD/WORnl. As the functional class progressed from Class II to III, the ratio of fixed defect (both WORnl and WORabn) to RD increased, but it was not statistically significant. In 2 patients in whom Ex SPECT's were repeated because of the progression of the chest pain, the severity of the perfusion abnormality also progressed. Perfusion abnormalities were observed most frequently in anterior (35%), then inferior/posterior (20%) and septal wall (18%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of left ventricular function by gated cardiac blood-pool emission computed tomography using a rotating gamma camera]

To elucidate the usefulness of gated cardiac blood-pool single photon emission CT (SPECT) with Tc-99m for the evaluation of left ventricular (LV) global and regional functions, 18 patients with coronary artery disease were studied. Thirty-two gated projection images were obtained over 360-degree at 16 frames per cardiac cycle. As LV volume was calculated by integrating the numbers of voxels which constituted LV and multiplying by the volume of a single voxel (0.1143 ml), we performed phantom studies to determine the appropriate cut-off level to detect LV outline. These cut-off levels were affected by the background activity and organ volume itself. So we constructed Volume-Cut-Level-Curve at each background activity. In clinical studies, short axis images which constituted LV were selected and provisional LV volumes were calculated at the cut-off levels of 45, 50 and 55%. These volumes were plotted on the Volume-Cut-Level-Curve and the true cut-off levels were obtained to calculate LV end-diastolic or end-systolic volume (EDV, ESV). The cut-off levels were different at every patient and ED or ES. EDV, ESV and LV ejection fraction obtained by SPECT were correlated well with those obtained by contrast ventriculography (LVG) (r = 0.89, 0.94, 0.94 each, p less than 0.01). For the LV wall motion analysis, LVGs obtained at two projections were compared with SPECT or gated cardiac blood-pool planar imaging (Planar) in 5 segments. In addition to visual comparison, wall motion scores (WMS) based on the degree of wall motion abnormality were calculated in each segment. Correlation of WMS between LVG and SPECT (r = 0.84) was significantly (p less than 0.01) superior to that between LVG and Planar (r = 0.62). Especially in SPECT, wall motion analyses at septal and infero-posterior segments were superior to those in Planar. Although gated SPECT requires relatively long time to perform, it is a useful method to detect LV global and regional functions.

[Left ventricular diastolic filling in elder patients with systemic hypertension]

To study the significance of left ventricular (LV) diastolic filling in elder patients with hypertension (HT), cardiac blood pool imagings with Tc-99m were obtained at rest in 17 normal subjects and 28 patients with systemic hypertension. The patients with hypertension did not show any evidence of coronary heart disease, renal insufficiency or other disease. Moreover, they showed normal LV ejection fraction (LVEF) and normal LV wall motion. They were divided into 4 groups: 1) normal-young (less than 60 years old, n = 10), 2) normal-old (greater than or equal to 65 years old, n = 7), 3) HT-young (less than 60 years old, n = 15), 4) HT-old (greater than or equal to 65 years old, n = 13). From the LV volume curve and its first differentiation curve, LVEF, mean first third ejection rate (ERm) and peak ejection rate (PER) were obtained as indices of the LV systolic function, and LV diastolic filling rate during the first third of diastole (FRm) and peak filling rate (PFR) were obtained as indices of LV diastolic function. All indices of LV systolic function were similar in all groups. In contrast, LV diastolic indices (FRm and PFR) of older groups were significantly lower than those of young groups both in HT and normal. Also, LV diastolic indices in HT groups decreased significantly in comparison with normal groups of the same age group. Among diastolic indices, FRm could distinguish patients with HT from normal subjects of the same age group more accurately than PFR.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical experience with chemotherapy using sulbactam/cefoperazone for severe infections accompanying malignant hematological disorders]

Clinical and bacteriological efficacies of sulbactam/cefoperazone (SBT/CPZ) were studied in 44 patients with serious infections associated with hematological malignancy. 1. SBT/CPZ was clinically effective in 33 cases (76.7%). Excellent effects were obtained in 23 cases, good effects in 10 cases and fairly good effects in 7 cases. Clinical effectiveness of SBT/CPZ was not dependent on neutrophil number in peripheral blood. 2. Bacteriologically SBT/CPZ was effective against all of the isolated organisms from 21 cases. 3. Adverse reactions were not significant except one case with eruption, 2 cases with abnormalities in hepatic function tests and 3 cases with abnormalities in renal function tests.

Myocardial perfusion in silent myocardial ischemia: investigation by exercise stress myocardial tomography with thallium-201

To investigate myocardial perfusion in silent myocardial ischemia, we performed exercise stress myocardial tomography with thallium-201 (T1) in 85 patients with coronary artery disease (CAD). Exercise stress myocardial tomography was obtained both immediately after exercise and three hours later. Patients were classified into two groups according to the presence (Symptomatic Group, n = 36) or absence (Silent Group, n = 49) of chest pain during exercise stress. Clinical features (age, gender and history of myocardial infarction) and arteriographically determined severity of CAD were the same in both groups. The extent of myocardial ischemia (% Ischemia) estimated by exercise stress myocardial tomography was the same in each group (30 +/- 10% in Silent Group, 28 +/- 12% in Symptomatic Group, NS). The severity of exercise-induced myocardial ischemia was expressed as a minimal value of myocardial T1 washout rate (minimal WOR) of each patient. Although exercise heart rate was identical in both groups, minimal WOR in Silent Group was significantly higher than that of Symptomatic Group (4 +/- 10% vs -16 +/- 14%, p less than 0.001). The study in patients who exhibited both silent and symptomatic ischemia showed same results. These findings suggest that the severity of ischemia is a fundamental factor in determining the presence or absence of pain during exercise induced ischemia.

[Transient myeloproliferative disorder (TMD) with transiently increased tetrasomy-21 cells in a phenotypically normal newborn]

We reported a case of TMD with transient increase of tetrasomy-21 cells in a phenotypically normal newborn. The patient was admitted to the St. Marianna University Hospital due to hepatosplenomegaly on the 7th days after birth. Hematological findings on admission revealed remarkable leukocytosis (168,300/microliters) with 79% blasts. Immunological studies of the blasts showed a positive reaction for platelet associated antigens, KOR-P77, AN50, TP80 and a pan-T antigen, TP40. Cytochemically blasts were strongly positive for acid phosphatase, positive for alpha NAE and weakly positive for PAS. The platelet peroxidase reaction was observed in rough endoplasmic reticulum of blast cells. Both immunological and cytochemical findings suggested that the blasts were of megakaryocyte lineage. Chromosomal analysis of the blasts showed 48, XX, + 21, +21 (21 tetrasomy). After chemotherapy with PSL and 6MP, bone marrow showed a complete remission. But we thought it was spontaneous remission because PSL and 6MP were not effective to acute megakaryocytic leukemia (AMKL). Bone marrow cells were karyotypically normal on the 67th day of life when abnormal blasts were not observed in the bone marrow.

[The usefulness of preoperative exercise stress myocardial single photon emission CT with thallium-201 to predict the responses to coronary revascularization]

To evaluate the usefulness of preoperative exercise stress (Ex) myocardial single photon emission CT (SPECT) with thallium-201 to predict the responses to coronary revascularization (CRV), Ex-SPECT's were obtained in 42 patients with coronary artery disease (CAD). In 34 patients angioplasty was performed and in 18 patients coronary bypass surgery was undergone. Before and after CVR, Ex-SPECT's were obtained both at immediately after Ex (Initial) and 3 hours later (RD) by the rotating gamma camera. Initial images before CRV showed definite perfusion defects (+3) in 76 myocardial segments. Perfusion abnormalities at RD images were graded into 4 (+3 to 0) by visual interpretation. "+3" indicated fixed defect and "0" indicated no perfusion abnormality. At RD images 17 segments showed fixed defect and 59 segments showed improved perfusion more than one grade. After CRV, all 59 segments with improved perfusion at RD images showed improvement of perfusion in comparison with initial images before CRV. Out of 17 segments with fixed defect before CRV, 14 segments showed perfusion defect with +3, while 3 segments showed improved perfusion after CRV. These 3 segments had ECG evidence of myocardial infarction. In these 3 segments, Ex-SPECT's before CRV showed abnormally low myocardial T1 washout rate (WOR) despite they indicated fixed defect visually. On the contrary, other 14 segments with fixed defect showed normal WOR before CRV. In conclusion, visually interpreted Ex-SPECT's before CRV predict the myocardial perfusion after CRV in most of cases.2+n a small

[The safety and diagnostic accuracy of dipyridamole-loading myocardial tomography with thallium-201 in the elderly with coronary artery disease]

To test the diagnostic accuracy and safety of dipyridamole-loading myocardial imaging with thallium-201 (T1) in the elderly, we performed myocardial tomography in 42 patients with coronary artery disease (CAD). While monitoring of ECG and blood pressure, dipyridamole was infused at a rate of 0.57 mg/kg body weight over 4 minutes, and 4 minutes later T1 (3 mCi) was injected. Five minutes later (initial) and 3 hours after T1 injection (redistribution) myocardial images were obtained from 32 projections by a rotating gamma camera. After low-pass filtering, images were reconstructed into short-axis, horizontal long-axis and vertical long-axis tomograms. Myocardial T1 distribution both on initial and redistribution images and myocardial T1 washout rate's (WOR) of the entire left ventricle were expressed into two-dimensional polar maps by using short-axis cuts (bull's-eye maps). In addition to visual interpretation, abnormal WOR (less than 18%) was used as a criteria of dipyridamole induced myocardial ischemia. Patients were divided into 2 groups. Group I consisted of 24 patients more than 70 years of age and Group II consisted of 18 patients less than 65 years of age. The clinical and coronary angiographic characteristics of the two groups did not differ. The sensitivity of this method for the detection of CAD was identical (83%) between the 2 groups, and the detection of coronary artery stenosis was 73% in Group I and 74% in Group II (NS).(ABSTRACT TRUNCATED AT 250 WORDS)