Endocytosed dsRNAs induce lysosomal membrane permeabilization that allows cytosolic dsRNA translocation for Drosophila RNAi responses.

RNA interference (RNAi) is a gene-silencing mechanism triggered by the cytosolic entry of double-stranded RNAs (dsRNAs). Many animal cells internalize extracellular dsRNAs via endocytosis for RNAi induction. However, it is not clear how the endocytosed dsRNAs are translocated into the cytosol across the endo/lysosomal membrane. Herein, we show that in Drosophila S2 cells, endocytosed dsRNAs induce lysosomal membrane permeabilization (LMP) that allows cytosolic dsRNA translocation. LMP mediated by dsRNAs requires the lysosomal Cl-/H+ antiporter ClC-b/DmOstm1. In clc-b or dmostm1 knockout S2 cells, extracellular dsRNAs are endocytosed and reach the lysosomes normally but fail to enter the cytosol. Pharmacological induction of LMP restores extracellular dsRNA-directed RNAi in clc-b or dmostm1-knockout cells. Furthermore, clc-b or dmostm1 mutant flies are defective in extracellular dsRNA-directed RNAi and its associated antiviral immunity. Therefore, endocytosed dsRNAs have an intrinsic ability to induce ClC-b/DmOstm1-dependent LMP that allows cytosolic dsRNA translocation for RNAi responses in Drosophila cells.

High-dose cytarabine plus gemtuzumab ozogamicin as consolidation therapy in patients with favorable- or intermediate-risk acute myeloid leukemia.

Previous prospective randomized trials have investigated the efficacy of gemtuzumab ozogamicin in the frontline treatment of acute myeloid leukemia (AML). We evaluated the efficacy of high-dose cytarabine with GO as consolidation therapy in 20 patients with favorable- or intermediate-risk AML in first complete remission. They included six patients with wild-type nucleophosmin (NPM1) core binding factor (CBF), ten with NPM1-mutated non-CBF, and four with wild-type NPM1 non-CBF. The median follow-up for the entire cohort was 62.0 months. The three-year overall survival (OS) and relapse-free survival (RFS) rates were 72.2% and 77.8%, respectively. OS and RFS were significantly higher for NPM1-mutated non-CBF AML than for wild-type NPM1 non-CBF AML (p = 0.001). We also examined the CD33 single-nucleotide polymorphism (SNP) rs12459419, which has been reported to influence the therapeutic efficacy of GO and CD33 expression. The CD33 expression ratio was higher in CD33 SNP C/C than in C/T (83.1% vs. 49.8%, p = 0.035), but 3-year OS and RFS did not differ significantly. These results suggest that consolidation therapy with high-dose cytarabine plus GO is highly effective in transplant-ineligible elderly patients and may be a reasonable treatment, especially for NPM1-mutated AML.

CRISPR/Cas9 gene editing clarifies the role of CD33 SNP rs12459419 in gemtuzumab ozogamicin-mediated cytotoxicity.

The single-nucleotide polymorphism (SNP) rs12459419 is located at the intron/exon junction of CD33 exon2. When exon2 is skipped by this CD33 SNP, the full-length CD33 (CD33FL) is converted to a short CD33 isoform (CD33D2). Since gemtuzumab ozogamicin (GO) only recognizes CD33FL, the CD33 SNP may affect the clinical efficacy of GO. To elucidate the significance of CD33 SNP on GO reactivity, we leveraged the CRISPR/Cas9 genome-editing system to create OCI-AML3 cell lines with specifically modified CD33 SNPs. Levels of CD33 D2 mRNA were significantly higher in the T/T clone (p < 0.001), but CD33D2 protein was not detectable in any clones. There was no significant difference in CD33FL mRNA expression across edited clones, and CD33FL protein expression was lowest in T/T clones, followed by T/C and C/C. Cytotoxicity assays revealed that the IC50 of GO was significantly lower in T/C and C/C clones than in the T/T clone (p < 0.001). Our study demonstrated a difference in GO-induced cytotoxicity in CD33 SNP-edited clones, clearly indicating that at least one CD33 SNP allele, rs12459419 C, is important for sensitivity to GO.

[Successful induction therapy for acute myeloid leukemia under management with extracorporeal membrane oxygenation].

A 53-year-old woman presented with shortness of breath and hyperleukocytosis and was admitted to our hospital. Shortly after, she went into cardiopulmonary arrest and was resuscitated. Her white blood cell count was 566,000/µl, with 94.5% cup-like blasts positive for MPO staining and FLT3-ITD positive, so she was diagnosed with acute myeloid leukemia (AML) M1. She also had disseminated intravascular coagulation and tumor lysis syndrome. Extracorporeal membrane oxygenation (ECMO) was started to manage bilateral pulmonary thromboembolism that had developed due to deep vein thrombosis, and induction therapy was performed under ECMO. On the third day of illness, the patient developed cerebral hemorrhage. Hematological remission was confirmed on the 39th day of illness. After consolidation therapy with chemotherapy and an FLT3 inhibitor, she underwent allogeneic hematopoietic stem cell transplantation, and remains alive. Case reports suggest strong evidence of mortality benefit from ECMO in patients with hematologic malignancies, particularly when ECMO served as a bridge through chemotherapy. Our patient suffered from cardiopulmonary arrest due to hyperleukocytosis and pulmonary thromboembolism, but was saved by induction of remission under ECMO. Improvements in supportive care should lead to reduction in early deaths during induction therapy.

Validation of a Supportive and Palliative Care Indicator Tool Among Patients Hospitalized Due to Heart Failure.

BACKGROUND: Palliative care, including symptom alleviation and advance-care planning, is relevant for patients with heart failure (HF). The Supportive and Palliative Care Indicator Tool (SPICT) is a tool for identifying patients who may benefit from palliative-care assistance but has not been validated in patients hospitalized due to HF. METHODS AND RESULTS: Clinical backgrounds, symptom burdens and outcomes were evaluated using the SPICT as assessed on admission in consecutive hospitalized patients with HF. SPICT-positive was defined when 2 or more general indicators and a New York Heart Association class ≥ III were present. Of 601 patients hospitalized due to HF (mean age: 79 ± 12 years; male, 314 [52%]; and mean left ventricular ejection fraction: 44 ± 18%), 100 (17%) patients were SPICT-positive. SPICT-positive patients were older (85 ± 9 vs 78 ± 12 years; P < 0.001) and had higher clinical frailty scales (6 ± 1 vs 4 ± 1 points; P < 0.001), whereas symptom burdens assessed by the Integrated Palliative care Outcome Scale were not different (17 [13, 28] vs 20 [11, 26] points; P = 0.97) when compared with patients who were SPICT-negative. During the median follow-up period of 518 days, 178 patients (30%) died. Being SPICT-positive was independently associated with higher all-cause mortality (hazard ratio: 3.49, 95% confidence interval: 2.41-5.05; P < 0.001) after adjusting for age, sex, New York Heart Association class IV, Get-With-The-Guideline risk score, N-terminal pro B-type natriuretic peptide levels, and left ventricular ejection fractions. CONCLUSIONS: In patients admitted for HF, being SPICT-positive was significantly associated with higher all-cause mortality rates, suggesting the utility of the SPICT as an indicator to initiate advance-care planning for end-of-life care among patients hospitalized due to HF.

Analysis of Protein Digestion and Absorption Using a Ussing Chamber to Simulate the Environment in the Digestive Tract.

The Ussing chamber is a tool for analyzing drug absorption. We investigated whether the Ussing chamber can be used to analyze the process from digestion to absorption of protein in the gastrointestinal tract. Mixtures containing infant formula, whole cow's milk, processed soy milk, enteral nutrition, or human breast milk, were placed in the apical membrane side equipped with Caco-2 cells. After the addition of first pepsin then pancreatin, samples from the apical and basal membranes were collected. Infant formula showed the highest digestibility and absorption rate. This may be attributed to the presence of whey protein, which is rapidly digested and absorbed. The digestion and absorption of human breast milk showed different results in each donor, suggesting that digestion and absorption may vary among individuals. We concluded that the Ussing chamber can continuously analyze the process from digestion to absorption of proteins in the gastrointestinal tract.

[Successful immunosuppressive therapy in female hemophilia A developing inhibitor after perioperative administration of factor VIII products].

A 62-year-old woman was diagnosed as a hemophilia A carrier (factor VIII activity 35%) on preoperative examination of an ovarian tumor. A total of 35,600 units of recombinant factor VIII products was administered perioperatively. On postoperative day 95, a subcutaneous hematoma formed and immunosuppressive therapy with prednisolone was started based on an APTT of 66 seconds, factor VIII (FVIII) activity of 3%, and FVIII inhibitor of 1 BU/ml. During this treatment, the patient was hospitalized due to ankle joint bleeds and required hemostatic treatment, but the inhibitor disappeared and FVIII activity recovered to 30% after postoperative day 438 with cyclophosphamide. F8 analysis revealed the patient carried a heterozygosity of p.Arg391Cys, which has previously been categorized as cross-reacting material (CRM)-positive severe hemophilia A. No high-risk mutations for inhibitor development were found. We also report the results of a desmopressin acetate hydrate test administered to the patient to prepare for future treatment in case of hemorrhage, since high-dose FVIII administration may have been a factor in inhibitor development.

Correlation of ex vivo and in vivo ammonia production with L-asparaginase biological activity in adults with lymphoid malignancies.

Silent inactivation of L-asparaginase (L-Asp) represents rapid clearance of L-Asp by anti-L-Asp IgG antibodies without clinical symptoms. Measurement of L-Asp activity is the gold standard for diagnosis of silent inactivation, but this test is not commercially available in Japan as of 2023. We evaluated ex vivo and in vivo ammonia production in relation to L-Asp activity. Blood samples from ten adult patients treated with L-Asp were collected to measure ammonia levels and L-Asp activity before the first dose and 24 h after the last dose of L-Asp, during each cycle of treatment. Plasma ammonia levels were analyzed immediately and 1 h after incubation at room temperature, and ex vivo ammonia production was defined as the increase in ammonia concentration. Ex vivo ammonia production correlated with L-Asp activity (R2 = 0.741), and ammonia levels measured immediately after blood collection were moderately correlated with L-Asp activity (R2 = 0.709). One patient with extranodal NK/T-cell lymphoma showed an increase in ammonia levels during the first cycle, but no increase in ammonia levels or L-Asp activity after L-Asp administration during the second cycle. Both ex vivo and in vivo ammonia production and surrogate markers are used for L-Asp biological activity.

Subcorneal pustular dermatosis-type IgA pemphigus associated with multiple myeloma: A case report and literature review.

Immunoglobulin A (IgA) pemphigus, also known as intercellular IgA dermatosis, is a rare autoimmune bullous disease presenting with IgA anti-keratinocyte cell surface autoantibodies. Concomitant lymphoproliferative disorders have been reported in IgA pemphigus, including IgA monoclonal gammopathy of undetermined significance and IgA type multiple myeloma (MM). A 35-year-old Japanese woman with a 3-year history of pruritic papulovesicles on her lower legs and trunk was referred to our department. Histopathological examination revealed acantholytic blisters, and results of both direct and indirect immunofluorescence were negative. Direct and indirect immunofluorescence were still negative 3 years and 7 months later. Approximately 7 years after her first visit, the patient was re-referred to us because of disease exacerbation. Histopathological findings revealed subcorneal blistering with acantholysis, in which neutrophil-dominant inflammatory cells were present. Indirect immunofluorescence was positive for IgA on the epidermal cell surface and both desmoglein (Dsg) 1/3 and (Dsc) desmocollin 1-3 enzyme-linked immunosorbent assays (ELISAs) for IgA were positive. The histological findings and positive Dsc1 IgA ELISA led to the diagnosis of subcorneal pustular dermatosis (SPD)-type IgA pemphigus. Further examination revealed hyper-IgA globulinemia, increased serum IgA-κ protein, and increased plasma cells in the bone marrow, enabling the diagnosis of IgA type MM. Daratumumab, lenalidomide, and dexamethasone (DLd) therapy was effective for both the MM and the skin lesions, resulting in negative results on Dsg1/3 and Dsc1-3 IgA ELISAs. The association between IgA pemphigus and IgA type multiple myeloma remains unclear, and only seven cases including the present case have been reported. Literature review revealed associations between SPD-type and IgA κ chain in IgA pemphigus and MM, and that in most cases the onset or diagnosis of MM was simultaneous or occurred after the diagnosis of IgA pemphigus. Therefore, clinicians should be aware of the development of multiple myeloma during the clinical course of patients with SPD-type IgA pemphigus.

[FLT3-ITD and NPM1 mutation positive acute myeloid leukemia with cuplike blasts mimicking acute promyelocytic leukemia].

FMS-like tyrosine kinase 3 (FLT3) inhibitors improve the prognosis of FLT3-internal tandem duplication (ITD)-positive acute myeloid leukemia (AML). Case 1 is a 47-year-old male patient who presented with a white blood cell count (WBC) of 95,700/ml with 94% blast accompanied by cuplike nuclei, lactate dehydrogenase (LDH) of 2,434 IU/l, fibrin degradation products (FDP) of 476 mg/ml, and a bone marrow examination that revealed blastic marrow with chromosome 46, XY, positive FLT3-ITD, and positive nucleophosmin 1 (NPM1) mutation type A. Flow cytometry revealed that blasts were positive for CD33 and negative for CD34, CD117, and human leukocyte antigen-DR isotype (HLA-DR). The patient had no response to idarubicin combined cytarabine; however, qiuzartinib administration resulted in the first complete remission. Case 2 is a 71-year-old female patient, who presented with 94,900/ml of WBC with a 91% blast accompanied with cup-like nuclei, LDH of 19,03 IU/l, FDP of 112 mg/ml, and a peripheral blood examination that revealed chromosome 46, XX, positive FLT3-ITD, and positive NPM1 mutation type B. Flow cytometry revealed that blasts were positive for CD33 and negative for CD34, CD117, and HLA-DR. She had a partial response to venetoclax combined with azacytidine, and qiuzartinib administration resulted in the first complete remission. Both cases were CD34- and HLA-DR-negative with disseminated intravascular coagulation mimicking acute promyelocytic leukemia (APL). Additionally, recognizing the cuplike blasts is useful to differentiate FLT3 mutant AML from APL for the proper use of FLT3 inhibitors.

[Allogeneic hematopoietic stem cell transplantations for relapsed and refractory acute lymphoblastic leukemia following inotuzumab ozogamicin treatment].

Inotuzumab ozogamicin (InO) was administered in three cases of relapsed/refractory adult acute lymphoblastic leukemia (ALL) before allogeneic hematopoietic stem cell transplantation (allo-SCT). One case developed extremely severe sinusoidal obstruction syndrome (SOS) but recovered after receiving defibrotide therapy. A gap of 63 days in the SOS case was noted from the last administration of InO to allo-SCT, the duration was 133 and 86 days for the other two cases, and the remaining risk factors for SOS were comparable in the three cases. In contrast to gemtuzumab ozogamicin (GO), the interval between InO exposure and allo-SCT has not been reported as a risk for SOS. Nevertheless, this case suggests that the intervals should be as long as possible.

TAFRO Syndrome That Responded to Prednisolone-only Treatment: Evaluating Changes in IL-6.

Thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly (TAFRO) syndrome is a systemic inflammatory disorder characterized by the above-mentioned symptoms. Because of the similarity in phenotypes between TAFRO syndrome and decompensated liver cirrhosis, an accurate diagnosis is often difficult. We herein report a 62-year-old Japanese patient with TAFRO syndrome who was misdiagnosed with intractable ascites associated with liver cirrhosis. Improvement of symptoms after treatment with prednisolone was associated with interleukin-6 rather than C-reactive protein. The pathogenesis of TAFRO syndrome, which has similar clinical manifestations to liver cirrhosis, remains unclear, and our findings may help elucidate the concept of this condition.

X-ray Diffraction Analysis to Explore Molecular Traces of Eccentric Contraction on Rat Skeletal Muscle Parallelly Evaluated with Signal Protein Phosphorylation Levels.

We performed X-ray diffraction analyses on rat plantaris muscle to determine if there are strain-specific structural changes at the molecular level after eccentric contraction (ECC). ECC was elicited in situ by supramaximal electrical stimulation through the tibial nerve. One hour after a series of ECC sessions, the structural changes that remained in the sarcomere were evaluated using X-ray diffraction. Proteins involved in cell signaling pathways in the muscle were also examined. ECC elicited by 100, 75, and 50 Hz stimulation respectively developed peak tension of 1.34, 1.12 and 0.79 times the isometric maximal tetanus tension. The series of ECC sessions phosphorylated the forkhead box O proteins (FoxO) in a tension-time integral-dependent manner, as well as phosphorylated the mitogen-activated protein kinases (MAPK) and a protein in the mammalian target of rapamycin (mTOR) pathway in a maximal tension dependent manner. Compared to isometric contractions, ECC was more efficient in phosphorylating the signaling proteins. X-ray diffraction revealed that the myofilament lattice was preserved even after intense ECC stimulation at 100 Hz. Additionally, ECC < 75 Hz preserved the molecular alignment of myoproteins along the myofilaments, while 75-Hz stimulation induced a slight but significant decrease in the intensity of meridional troponin reflection at 1/38 nm-1, and of myosin reflection at 1/14.4 nm-1. These two reflections demonstrated no appreciable decrease with triple repetitions of the standard series of ECC sessions at 50 Hz, suggesting that the intensity decrease depended on the instantaneous maximal tension development rather than the total load of contraction, and was more likely linked with the phosphorylation of MAPK and mTOR signaling proteins.

A case of lymphomatoid granulomatosis with central nervous system involvement successfully treated with IFNα.

Lymphomatoid granulomatosis (LYG) is a rare Epstein-Barr virus (EBV)-driven B-cell lymphoproliferative disease affecting mainly extranodal sites such as the lung, central nervous system (CNS), skin, kidney, and liver. We report a case of low-grade LYG involving the CNS that was successfully treated with interferon alpha (IFNα). A 69-year-old woman developed necrotic erythema of the skin and was initially diagnosed with pyoderma gangrenosum based on skin biopsy. She showed a limited response to prednisolone. Approximately 6 months after the initial onset, low-grade LYG was diagnosed after detection of CNS lesions on brain biopsy. The whole blood EBV-DNA load determined by real-time polymerase chain reaction was slightly elevated. Two months into IFNα therapy, skin and CNS lesions had responded favorably and the EBV-DNA load decreased. IFNα plays an important role in treatment of LYG through its antiproliferative, immunomodulatory, and anti-EBV effects. To our knowledge, this is the first case report of successful treatment with IFNα in Japan. Further investigation is necessary to determine optimal use of IFNα for LYG.

[Use of pegylated granulocyte colony-stimulating factor in dose-adjusted EPOCH-R therapy].

Dose-adjusted (DA)-EPOCH-R causes profound neutropenia requiring relatively long hospital stays with multiple doses of granulocyte colony-stimulating factor (G-CSF). A single-dose pegylated G-CSF (PEG-G-CSF) has been used for the treatment of chemotherapy-induced neutropenia. We retrospectively examined 15 patients (median age 61, range 33-75 years) treated with DA-EPOCH-R. In the first cycle of the DA-EPOCH-R therapy, a G-CSF preparation was used, and since the second cycle, the G-CSF and PEG-G-CSF use groups were divided. The median length of hospitalization after starting chemotherapy in the second-cycle DA-EPOCH-R was significantly shorter with PEG-G-CSF group (n=9) of 9 (7-13) days compared with G-CSF group (n=6) of 18 (15-22) days (P<0.001). Risk factors of febrile neutropenia, such as bone marrow invasion, performance status, serum albumin, and history of febrile neutropenia at the first DA-EPOCH-R cycle or previous chemotherapy were not significantly different for both groups, and the incidence of febrile neutropenia in PEG-G-CSF and G-CSF groups was 2.6% and 46.9%, respectively. These analyses suggest that PEG-G-CSF can be combined with DA-EPOCH-R without compromising treatment outcomes as compared with the daily dose of G-CSF.

[Interleukin-6-producing paraganglioma mimicking multicentric Castleman disease].

Multicentric Castleman disease (MCD) comprises a heterogeneous group of lymphoproliferative disorders. Interleukin 6 (IL-6) plays an important role in the MCD pathophysiology. Here, we report the case of a 17-year-old Japanese man who presented with fever, headache, fatigue, and weight loss, with normal blood pressure. A movable mass was palpated in his lower abdomen. Laboratory tests revealed microcytic anemia and hypoalbuminemia, with elevated IL-6, sIL-2R, and vascular endothelial growth factor. Computed tomography of the abdomen demonstrated a 55-mm-diameter pelvic tumor and enlarged mesenteric lymph nodes. MCD was suspected, and the pelvic tumor resected. After the operation, his blood pressure rose slowly, and resulted to seizures of posterior reversible encephalopathy syndrome. Evaluation of hypertension revealed that plasma norepinephrine and normetanephrine concentrations were elevated, and pathological examinations showed that the resected tumor was positive for IL-6 and chromogranin-A. Therefore, we diagnosed the patient with IL-6-producing paraganglioma with MCD-mimicking symptoms. Moreover, IL-6-producing pheochromocytoma and paraganglioma should be included in differential diagnoses of MCD, even in normotensive patients.

Successful correction of factor V deficiency of patient-derived iPSCs by CRISPR/Cas9-mediated gene editing.

BACKGROUND: Factor V (FV) deficiency is a monogenic inherited coagulation disorder considered to be an ideal indication for gene therapy. To investigate the possibility of therapeutic application of genome editing, we generated induced pluripotent stem cells (iPSCs) from a FV-deficient patient and repaired the mutation of factor V gene (F5) using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9). METHODS: The patient's peripheral blood mononuclear cells were reprogrammed for iPSCs. The targeting vector was designed with homology arms against F5 containing the corrected sequence. Cas9 ribonucleoprotein (RNP) complex and targeting vector were electroporated into iPSCs. Gene-edited iPSCs were differentiated into hepatocyte-like cells (HLCs). RESULTS: The mutation of F5 in patient-derived iPSCs was repaired by CRISPR/Cas9. In concentrated culture supernatants of patient-derived iPS-HLCs, neither FV antigen nor activity was detected, while in those of gene-corrected iPS-HLCs, FV antigen and specific activity were 67.0 ± 13.1 ng/mL and 173.2 ± 41.1 U/mg, respectively. CONCLUSIONS: We successfully repaired the mutation of F5 using the CRISPR/Cas9 and confirmed the recovery of FV activity with gene-corrected iPS-HLCs. Gene-edited iPSCs are promising for elucidating the pathophysiology as well as for a modality of gene therapy.

Berberine-induced nucleolar stress response in a human breast cancer cell line.

We investigated the novel molecular mechanisms of the antitumor effect of berberine. In this study, two different human cell lines (breast cancer MCF7 cells and non-tumorigenic epithelial MCF12A cells) were treated with various concentrations of berberine. Treatment with 1 and 10 µM berberine inhibited proliferation with G0/G1 cell cycle arrest in both cell lines, and treatment with 100 µM berberine triggered a marked level of cell death in MCF7 cells but not in MCF12A cells. Berberine increased the level of p53 protein and of its target p21 both time- and dose-dependently in MCF7 cells. At any concentration of berberine, immediate uptake (within 15 min) followed by predominantly mitochondrial accumulation were observed by confocal microscopy in both cell lines. At high concentrations (10 or 100 µM), accumulation in the nucleolus became prominent after the transition to the nucleoplasm, especially remarkable in MCF7 cells. Therefore, we evaluated the possibility of berberine-induced nucleolar stress and observed the disappearance of ribosomal protein (RP)L5 from the nucleolus and accumulation of p53 protein in the nucleus after treatment with 10 or 100 µM berberine in MCF7 cells. We also detected the accumulation of RPL5 and RPL11 in the nucleoplasm fraction where they bind to Mdm2. Moreover, downregulation of RPL5 inhibited berberine-driven induction of p53 and p21 and cell death in MCF7 cells. Whereas, in MCF12A cells, down-regulation of RPL5 had little effect on the growth inhibitory effect of high concentration of berberine. These results indicated that cell growth inhibition and cell death induced by higher doses (>10 µM) of berberine in MCF7 cells were due to the upregulation of p53 under the nucleolar stress response caused by a significant accumulation of berberine in the nucleoli.

Crossbridge Recruitment Capacity of Wild-Type and Hypertrophic Cardiomyopathy-Related Mutant Troponin-T Evaluated by X-ray Diffraction and Mechanical Study of Cardiac Skinned Fibers.

X-ray diffraction and tension measurement experiments were conducted on rat left ventricular skinned fibers with or without "troponin-T treatment," which exchanges the endogenous troponin T/I/C complex with exogenous troponin-T. These experiments were performed to observe the structural changes in troponin-T within a fiber elicited by contractile crossbridge formation and investigate the abnormality of hypertrophic cardiomyopathy-related troponin-T mutants. The intensity of the troponin reflection at 1/38.5 nm-1 was decreased significantly by ATP addition after treatment with wild-type or mutant troponin-T, indicating that crossbridge formation affected the conformation of troponin-T. In experiments on cardiac fibers treated with the hypertrophic cardiomyopathy-related mutants E244D- and K247R-troponin-T, treatment with K247R-troponin-T did not recruit contracting actomyosin to a greater extent than wild-type-troponin-T, although a similar drop in the intensity of the troponin reflection occurred. Therefore, the conformational change in K247R-troponin-T was suggested to be unable to fully recruit actomyosin interaction, which may be the cause of cardiomyopathy.