ABSTRACT
Pathogenic variants in ABCA12 are important causative genetic defects for autosomal recessive congenital ichthyoses (ARCI), which include congenital ichthyosiform erythroderma (CIE), harlequin ichthyosis, and lamellar ichthyosis. In addition, pathogenic variants in ABCA12 are known to cause a localized nevoid form of CIE due to recessive mosaicism. We previously reported siblings who carried an ABCA12 variant but did not show a "congenital" phenotype. They were considered to have pityriasis rubra pilaris (PRP). Here, we present a further patient with ABCA12 variants whose phenotype was not congenital ichthyosis, in an independent family. Notably, these three patients had geographic unaffected areas. Such areas are not usually found in patients with ARCI who have ABCA12 variants, suggesting mild phenotypes for these patients. Interestingly, the histological features of the ichthyotic lesions in these patients resembled those of PRP. All three patients had homozygous pathogenic missense variants in ABCA12. Our findings expand the phenotypic spectrum of patients with ABCA12 variants.
Subject(s)
Ichthyosiform Erythroderma, Congenital , Ichthyosis, Lamellar , Ichthyosis , Pityriasis Rubra Pilaris , Humans , Pityriasis Rubra Pilaris/genetics , Ichthyosis, Lamellar/genetics , Ichthyosiform Erythroderma, Congenital/genetics , Ichthyosiform Erythroderma, Congenital/pathology , Phenotype , Mutation , ATP-Binding Cassette Transporters/geneticsABSTRACT
BACKGROUND/AIM: Breast cancer that is estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and human epidermal growth factor receptor-2 (HER2)-negative is termed triple-negative breast cancer (TNBC). Cytotoxic chemotherapy remains the first choice of treatment against TNBC due to lack of specific therapeutic targets. TNBC is not classified based on therapeutic targets, but recently, the development of targeted therapies - including immune checkpoint inhibitors and poly (adenosine diphosphate-ribose) polymerase inhibitors - has gained attention. This study aimed to examine a novel target-oriented TNBC classification to further facilitate targeted therapy by classifying TNBC based on the breast cancer 1 (BRCA1)-like as well as the protein expression of HER2, programmed death ligand 1 (PD-L1), androgen receptor (AR), cytokeratin 5/6, and epidermal growth factor receptor (EGFR). PATIENTS AND METHODS: We enrolled 17 patients with primary TNBC who did not receive preoperative chemotherapy and underwent surgery at the Kobe University Hospital, Japan, between January 1, 2018, and July 31, 2019. Immunohistochemical staining was performed on tumor specimens, while a BRCAness test was performed using multiplex ligation-dependent probe amplification (MLPA) analysis. A BRCAness score 0.5 or higher was considered BRCA1-like. RESULTS: Tumors were classified as HER2-low (immunohistochemistry score 1+ or 2+ and FISH negative), PD-L1 positive, AR positive, or BRCA1-like. HER2-low, PD-L1 positive, AR positive, and BRCA1-like were detected in 11 (64.7%), 4 (23.5%), 6 (35.3%), and 6 (35.3%) samples. The tumor of only one patient could not be classified into any of these categories. CONCLUSION: Almost all TNBC cases can be classified according to treatable targets.
Subject(s)
Triple Negative Breast Neoplasms , Humans , Triple Negative Breast Neoplasms/genetics , B7-H1 Antigen/genetics , Hospitals, University , Immune Checkpoint Inhibitors , Japan , Pentosyltransferases , Poly(ADP-ribose) PolymerasesABSTRACT
PURPOSE: The aim of the study was to evaluate the impact of adding an extensive pelvic peritoneal stripping procedure, termed "wide resection of the pelvic peritoneum," (WRPP) to standard surgery for epithelial ovarian cancer on survival effectiveness and to investigate the role of ovarian cancer stem cells (CSCs) in the pelvic peritoneum. METHODS: A total of 166 patients with ovarian cancer undergoing surgical treatment at Kumamoto University Hospital between 2002 and 2018 were retrospectively analyzed. Eligible patients were divided into three groups based on the surgical approach: standard surgery (SS) group (n = 36), WRPP group (standard surgery plus WRPP, n = 100), and rectosigmoidectomy (RS) group (standard surgery plus RS, n = 30). Survival outcomes were compared between the three groups. CD44 variant 6 (CD44v6) and EpCAM expression, as markers of ovarian CSCs, in peritoneal disseminated tumors were evaluated using immunofluorescence staining. RESULTS: With respect to patients with stage IIIA-IVB ovarian cancer, there were significant differences in overall and progression-free survival between the WRPP and SS groups, as revealed by univariate (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.17-0.69; P = 0.003 and HR, 0.54; 95% CI, 0.31-0.95; P = 0.032, respectively) and multivariate Cox proportional hazards models (HR, 0.35; 95% CI, 0.17-0.70; P = 0.003 and HR, 0.54; 95% CI, 0.31-0.95; P = 0.032, respectively). Further, no significant differences were observed in survival outcomes between the RS group and the SS or WRPP group. Regarding the safety of WRPP, no significant differences in major intraoperative and postoperative complications were found between the three groups. Immunofluorescence analysis revealed a high percentage of CD44v6/EpCAM double-positive ovarian cancer cells in peritoneal disseminated tumors. CONCLUSION: The present study demonstrates that WRPP significantly contributes to improved survival in patients with stage IIIA-IVB ovarian cancer. WRPP could result in eradicating ovarian CSCs and disrupting the CSC niche microenvironment in the pelvic peritoneum.
Subject(s)
Ovarian Neoplasms , Peritoneal Neoplasms , Humans , Female , Carcinoma, Ovarian Epithelial/surgery , Peritoneum/surgery , Epithelial Cell Adhesion Molecule , Retrospective Studies , Ovarian Neoplasms/pathology , Peritoneal Neoplasms/surgery , Tumor MicroenvironmentABSTRACT
OBJECTIVE: This study aimed to investigate the prevalence of genitourinary syndrome of menopause (GSM) in Japan using the Japanese translation of the Vulvovaginal Symptoms Questionnaire (VSQ) with online survey. In addition, we examined the relationship between sexual activity and GSM symptoms. METHODS: An online survey on GSM was conducted with 4,134 women aged 40 to 79 years, who were registered in an online survey company. Several questionnaires with Japanese translations of linguistic validity were used in this study. GSM was defined as a condition in women older than 40 years with vulvovaginal symptoms on the VSQ. RESULTS: The percentage of postmenopausal women 40 years and older was 69.6%. The percentage of women with sexual activity was 22%. The prevalence of GSM with vulvovaginal symptoms was 11.6%, and 31.7% in sexually active women. The prevalence of GSM was associated with age and was significantly lower in the 70s age group than in other age groups. Vulvar hurting and dryness were both age-related only in the sexual activity group, with a statistically significantly higher prevalence in the 70s group than in the 40s group. The prevalence of vulvar dryness during sexual activity was significantly lower in the 40s age group. CONCLUSIONS: An online epidemiological survey of GSM was conducted for the first time in Japan using the linguistically validated Japanese translation of the VSQ. The prevalence of GSM with genital or sexual symptoms was 11.6% in Japanese women 40 years and older, and 31.7% in sexually active women.
Subject(s)
Postmenopause , Vulvar Diseases , Female , Humans , Aged , Adult , Vagina/pathology , Japan/epidemiology , Vulvar Diseases/pathology , Epidemiologic Studies , Menopause , Atrophy/pathologyABSTRACT
BACKGROUND: Schnitzler syndrome is a rare disorder with chronic urticaria, and there is no report summarizing the current status in Japan. METHODS: A nationwide survey of major dermatology departments in Japan was conducted in 2019. We further performed a systematic search of PubMed and Ichushi-Web, using the keywords "Schnitzler syndrome" and "Japan" then contacted the corresponding authors or physicians for further information. RESULTS: Excluding duplicates, a total of 36 clinically diagnosed cases were identified from 1994 through the spring of 2022, with a male to female ratio of 1:1. The median age of onset was 56.5 years. It took 3.3 years from the first symptom, mostly urticaria, to reach the final diagnosis. The current status of 30 cases was ascertained; two patients developed B-cell lymphoma. SchS treatment was generally effective with high doses of corticosteroids, but symptoms sometimes recurred after tapering. Colchicine was administered in 17 cases and was effective in 8, but showed no effect in the others. Tocilizumab, used in six cases, improved laboratory abnormalities and symptoms, but lost its efficacy after several years. Rituximab, used in five cases, was effective in reducing serum IgM levels or lymphoma mass, but not in inflammatory symptoms. Four cases were treated with IL-1 targeting therapy, either anakinra or canakinumab, and achieved complete remission, except one case with diffuse large B-cell lymphoma. CONCLUSIONS: Since Schnitzler syndrome is a rare disease, the continuous collection and long-term follow-up of clinical information is essential for its appropriate treatment and further understanding of its pathophysiology.
Subject(s)
Chronic Urticaria , Schnitzler Syndrome , Urticaria , Humans , Male , Female , Middle Aged , Schnitzler Syndrome/diagnosis , Schnitzler Syndrome/drug therapy , Urticaria/diagnosis , Interleukin 1 Receptor Antagonist Protein/therapeutic use , Chronic Urticaria/drug therapy , Japan/epidemiologyABSTRACT
Colorectal cancer (CRC) is a heterogenous disease, and patients have differences in therapeutic response. However, the mechanisms underlying interpatient heterogeneity in the response to chemotherapeutic agents remain to be elucidated, and molecular tumor characteristics are required to select patients for specific therapies. Patient-derived organoids (PDOs) established from CRCs recapitulate various biological characteristics of tumor tissues, including cellular heterogeneity and the response to chemotherapy. Patient-derived organoids established from CRCs show various morphologies, but there are no criteria for defining these morphologies, which hampers the analysis of their biological significance. Here, we developed an artificial intelligence (AI)-based classifier to categorize PDOs based on microscopic images according to their similarity in appearance and classified tubular adenocarcinoma-derived PDOs into six types. Transcriptome analysis identified differential expression of genes related to cell adhesion in some of the morphological types. Genes involved in ribosome biogenesis were also differentially expressed and were most highly expressed in morphological types showing CRC stem cell properties. We identified an RNA polymerase I inhibitor, CX-5641, to be an upstream regulator of these type-specific gene sets. Notably, PDO types with increased expression of genes involved in ribosome biogenesis were resistant to CX-5461 treatment. Taken together, these results uncover the biological significance of the morphology of PDOs and provide novel indicators by which to categorize CRCs. Therefore, the AI-based classifier is a useful tool to support PDO-based cancer research.
Subject(s)
Adenocarcinoma , Antineoplastic Agents , Colorectal Neoplasms , Adenocarcinoma/drug therapy , Adenocarcinoma/genetics , Adenocarcinoma/metabolism , Antineoplastic Agents/pharmacology , Artificial Intelligence , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Humans , Organoids/metabolismABSTRACT
A 56-year-old female patient with left breast cancer presented at our hospital. Preoperative CT scan showed an isolated bilateral pectoralis major muscle defect and abnormal muscle originating from the entire sternum and inserting in the lower ribs and rectus sheath. Total mastectomy and axillary lymph node dissection were performed. We believe that this case is unique and that others like it have never been reported. If there is a defect in the pectoralis major muscle, reconstructive surgery with a tissue expander is contraindicated. Therefore, preoperative evaluation of the chest wall musculature on imaging is recommended.
ABSTRACT
Periodontal Ehlers-Danlos syndrome (pEDS) is an autosomal-dominant disorder first described by Stewart in 1977 that is characterized by severe gingival recession and periodontitis that triggers premature loss of permanent teeth and alveolar bone absorption. It was recently shown that pEDS is caused by a heterozygous missense mutation in C1R or C1S, which encode complement 1 proteases. Here, we report a familial case of pEDS with a novel heterozygous missense mutation, c.674G>C (p.R225P), in C1R (NM_001733.4). The case exhibited pretibial hyperpigmentation and extended periodontitis but neither skin extensibility nor joint hypermobility, suggesting that this mutation will expand the definition of pEDS.
Subject(s)
Ehlers-Danlos Syndrome , Joint Instability , Periodontitis , Ehlers-Danlos Syndrome/complications , Ehlers-Danlos Syndrome/diagnosis , Ehlers-Danlos Syndrome/genetics , Humans , Joint Instability/complications , Joint Instability/genetics , Mutation , Mutation, Missense , Periodontitis/etiology , SkinABSTRACT
OBJECTIVES: To evaluate the oncologic and obstetric outcomes of cervical conization followed by pelvic lymphadenectomy, which is used as a fertility-sparing procedure, in reproductive-aged patients with early-stage cervical cancer. METHODS: We performed a retrospective study of patients with stage IA1-IB1 cervical cancer who underwent cervical conization followed by pelvic lymphadenectomy from 2011 to 2020 at Kumamoto University Hospital. RESULTS: In total, eight patients underwent conization followed by pelvic lymphadenectomy. The median age of the patients was 33 (range: 28-36) years. Four (50.0%) patients were nulliparous. Seven (87.5%) patients were diagnosed with squamous cell carcinoma (87.5%) and one (12.5%) with adenocarcinoma. Five (62.5%), two (25.0%), and one (12.5%) presented with stage IA1, IA2, and IB1 disease, respectively. Five (62.5%) patients had lymphovascular space invasion (LVSI) based on the assessment of specimens obtained via conization. However, none had lymph node metastasis based on pelvic lymphadenectomy. Regarding long-term oncologic outcomes, recurrence was not observed at a median follow-up of 60 (range: 8-107) months. In addition, obstetric outcomes were consistently favorable in terms of achieving pregnancy, preterm delivery, and live birth. During the study period, two patients who actively attempted to conceive had four pregnancies, resulting in full-term deliveries, and one was on her first trimester of pregnancy. CONCLUSION: Cervical conization combined with pelvic lymphadenectomy represents a feasible conservative management for histologically well-selected patients with early-stage cervical cancer. Furthermore, an optimal histopathological evaluation of conization specimens will contribute to decision-making regarding the use of this fertility-sparing procedure.
Subject(s)
Fertility Preservation , Uterine Cervical Neoplasms , Adult , Conization/methods , Feasibility Studies , Female , Fertility Preservation/methods , Humans , Infant, Newborn , Lymph Node Excision/methods , Neoplasm Staging , Pregnancy , Retrospective Studies , Uterine Cervical Neoplasms/pathology , Uterine Cervical Neoplasms/surgeryABSTRACT
A 44-years-old woman who underwent bilateral mastectomy was treated with chemotherapy after axillary lymph nodes and liver metastases recurrence. She was referred to our hospital for BRCA1/2 germline test and the test revealed BRCA2 pathogenic mutation. Before the administration of olaparib as the fourth-line therapy, liver dysfunction, caused by extensive liver metastasis, was observed. The liver damage improved, and tumor markers decreased immediately as shown in the blood test and CT examination results after 2 months; indicating marked reduction of liver metastasis. In the OlympiAD trial, the patients received olaparib as either the first-, second- or third-line treatment; however, few data on the efficacy of olaparib in the patients, as a late line treatment, were reported. In this article, we report a case of a woman in whom olaparib was used as the fourth-line treatment for metastatic recurrent breast cancer. A high therapeutic effect was obtained and the quality of life has been maintained in her for the past 1 year.
Subject(s)
Breast Neoplasms , Adult , Breast Neoplasms/drug therapy , Female , Germ-Line Mutation , Humans , Mastectomy , Neoplasm Recurrence, Local , Phthalazines , Piperazines , Quality of LifeSubject(s)
Embolism , Rubber , Coloring Agents , Embolism/diagnosis , Humans , Polymers/adverse effects , Staining and LabelingABSTRACT
Metastasis is the major cause of cancer-related death, but whether metastatic lesions exhibit the same cellular composition as primary tumors has yet to be elucidated. To investigate the cellular heterogeneity of metastatic colorectal cancer (CRC), we established 72 patient-derived organoids (PDOs) from 21 patients. Combined bulk transcriptomic and single-cell RNA-sequencing analysis revealed decreased gene expression of markers for differentiated cells in PDOs derived from metastatic lesions. Paradoxically, expression of potential intestinal stem cell markers was also decreased. We identified OLFM4 as the gene most strongly correlating with a stem-like cell cluster, and found OLFM4+ cells to be capable of initiating organoid culture growth and differentiation capacity in primary PDOs. These cells were required for the efficient growth of primary PDOs but dispensable for metastatic PDOs. These observations demonstrate that metastatic lesions have a cellular composition distinct from that of primary tumors; patient-matched PDOs are a useful resource for analyzing metastatic CRC.
Subject(s)
Colorectal Neoplasms/pathology , Granulocyte Colony-Stimulating Factor/metabolism , Organoids/metabolism , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Colorectal Neoplasms/genetics , Colorectal Neoplasms/surgery , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Humans , Neoplasm Metastasis , Organoids/pathologyABSTRACT
Pralatrexate has been approved for the treatment of relapsed/refractory peripheral T cell lymphomas. Studies in the U.S. also support the clinical efficacy of pralatrexate to treat advanced-stage cutaneous T-cell lymphomas, but outcomes in Japanese patients have not yet been reported. We herein describe two Japanese patients with heavily-pretreated relapsed/refractory mycosis fungoides that were successfully controlled by pralatrexate.
Subject(s)
Mycosis Fungoides , Skin Neoplasms , Aminopterin/analogs & derivatives , Humans , Japan , Mycosis Fungoides/drug therapy , Neoplasm Recurrence, Local , Skin Neoplasms/drug therapyABSTRACT
Cytoplasmic dynein is a dimeric motor protein which processively moves along microtubule. Its motor domain (head) hydrolyzes ATP and induces conformational changes of linker, stalk, and microtubule binding domain (MTBD) to trigger stepping motion. Here we applied scattering imaging of gold nanoparticle (AuNP) to visualize load-free stepping motion of processive dynein. We observed artificially-dimerized chimeric dynein, which has the head, linker, and stalk from Dictyostelium discoideum cytoplasmic dynein and the MTBD from human axonemal dynein, whose structure has been well-studied by cryo-electron microscopy. One head of a dimer was labeled with 30 nm AuNP, and stepping motions were observed with 100 µs time resolution and sub-nanometer localization precision at physiologically-relevant 1 mM ATP. We found 8 nm forward and backward steps and 5 nm side steps, consistent with on- and off-axes pitches of binding cleft between αß-tubulin dimers on the microtubule. Probability of the forward step was 1.8 times higher than that of the backward step, and similar to those of the side steps. One-head bound states were not clearly observed, and the steps were limited by a single rate constant. Our results indicate dynein mainly moves with biased small stepping motion in which only backward steps are slightly suppressed.
Subject(s)
Axonemal Dyneins/chemistry , Cytoplasmic Dyneins/chemistry , Dictyostelium/chemistry , Protozoan Proteins/chemistry , Axonemal Dyneins/metabolism , Biochemical Phenomena , Cryoelectron Microscopy , Dictyostelium/metabolism , Gold/chemistry , Humans , Metal Nanoparticles/chemistry , Microtubules/chemistry , Microtubules/metabolism , Protein Binding , Protozoan Proteins/metabolism , Tubulin/chemistry , Tubulin/metabolismABSTRACT
DNA replication is initiated at replication origins on chromosomes at their scheduled time during S phase of the cell cycle. Replication timing control is highly conserved among eukaryotes but the underlying mechanisms are not fully understood. Recent studies have revealed that some telomere-binding proteins regulate replication timing at late-replicating origins throughout the genome. To investigate the molecular basis of this process, we analyzed the effects of excessive elongation of telomere DNA on replication timing by deleting telomere-associated shelterin proteins in Schizosaccharomyces pombe. We found that rap1∆ and poz1∆ cells showed abnormally accelerated replication at internal late origins but not at subtelomere regions. These defects were suppressed by removal of telomere DNA and by deletion of the telomere-binding protein Taz1. Furthermore, Sds21-a counter protein phosphatase against Dbf4-dependent kinase (DDK)-accumulated at elongated telomeres in a Taz1-dependent manner but was depleted at internal late origins, indicating that highly elongated telomeres sequester Sds21 at telomeres and perturb replication timing at internal regions. These results demonstrate that telomere DNA length is an important determinant of replication timing at internal regions of chromosomes in eukaryotes.
Subject(s)
DNA Replication Timing/genetics , DNA, Fungal/metabolism , Replication Origin , Schizosaccharomyces pombe Proteins/metabolism , Schizosaccharomyces/genetics , Telomere/genetics , Cell Cycle , DNA, Fungal/genetics , Schizosaccharomyces/growth & development , Schizosaccharomyces/metabolism , Schizosaccharomyces pombe Proteins/genetics , Shelterin Complex , Telomere-Binding Proteins/genetics , Telomere-Binding Proteins/metabolismABSTRACT
Extracorporeal membrane oxygenation through cervical cannulation is an established option for pediatric patients with acute cardiopulmonary failure. However, left-sided heart decompression is sometimes mandatory in patients with severe left ventricular dysfunction. This report describes a fast and less invasive technique for placing a left atrial cannula through a left anterior minithoracotomy approach. In 4 critically ill children, this minimally invasive technique provided satisfactory left-sided heart decompression, and this report describes a representative case.
Subject(s)
Decompression, Surgical/methods , Extracorporeal Membrane Oxygenation/methods , Heart Atria/surgery , Heart Failure/surgery , Minimally Invasive Surgical Procedures/methods , Myocarditis/complications , Thoracotomy/methods , Acute Disease , Child , Echocardiography , Follow-Up Studies , Heart Failure/etiology , Heart Failure/physiopathology , Heart-Assist Devices , Humans , Male , Myocarditis/diagnosis , Myocarditis/physiopathology , Stroke Volume/physiologyABSTRACT
BACKGROUND: Psoriasis is an inflammatory disease associated with aberrant crosstalk between the epidermis and immune system. However, the role of Langerhans cells (LCs) in psoriasis remains controversial. OBJECTIVES: To elucidate whether LCs are functionally involved in the development of psoriasis using a mouse model. METHODS: Two lines of transgenic mice were used and crossed. They included K5.Stat3C, the psoriasis-model mouse and langerin DTR knock-in (KI) mouse. We performed immunofluorescence staining for LCs in psoriatic lesion of human and model mice. Flow cytometric analyses were performed to compare between dendritic cells (DCs) and LCs in the epidermis and skin-draining lymph nodes (sDLNs). To assess cytokine/chemokine expression in the skin lesion or primary cultured keratinocytes, we performed RT-PCR, microarray analysis or intracellular staining on the flow cytometer. RESULTS: LCs were activated in psoriatic lesion of patients with psoriasis and K5.Stat3C mice. Compared with non-transgenic mice, K5.Stat3C mice constitutively showed an increased number of LCs in the sDLNs before psoriasis-like lesion developed. Stat3C transgenic keratinocytes expressed an elevated level of IL-1α. Psoriasis-like lesion in K5.Stat3C mice were attenuated in the absence of LCs, indicating that LCs were essential to the development of psoriasis-like lesion. Furthermore, we also recognized that epidermal LCs in psoriatic lesion of not only K5.Stat3C mice but also psoriasis patients produced IL-23. CONCLUSIONS: Our study suggests that Stat3 activation in keratinocytes may impact on LC activation in situ via IL-1α stimulation, at least in part, and that their presence may be essential for the pathogenesis of psoriasis through producing IL-23.
Subject(s)
Interleukin-23/immunology , Keratinocytes/pathology , Langerhans Cells/immunology , Psoriasis/immunology , STAT3 Transcription Factor/metabolism , Animals , Antigens, Surface/genetics , Antigens, Surface/metabolism , Biopsy , Cells, Cultured , Disease Models, Animal , Healthy Volunteers , Humans , Interleukin-1alpha/immunology , Interleukin-1alpha/metabolism , Interleukin-23/metabolism , Keratinocytes/immunology , Lectins, C-Type/genetics , Lectins, C-Type/metabolism , Mannose-Binding Lectins/genetics , Mannose-Binding Lectins/metabolism , Mice , Mice, Transgenic , Primary Cell Culture , Psoriasis/pathology , Skin/cytology , Skin/pathologyABSTRACT
Gold nanoparticles (AuNPs) have been used as a contrast agent for optical imaging of various single biomolecules. Because AuNPs have high scattering efficiency without photobleaching, biomolecular dynamics have been observed with nanometer localization precision and sub-millisecond time resolution. To understand the working principle of biomolecular motors in greater detail, further improvement of the localization precision and time resolution is necessary. Here, we investigated the lower limit of localization precision achievable with AuNPs and the fundamental law, which determines the localization precision. We first used objective-lens-type total internal reflection dark-field microscopy to obtain a scattering signal from an isolated AuNP. The localization precision was inversely proportional to the square root of the photon number, which is consistent with theoretical estimation. The lower limit of precision for a 40 nm AuNP was â¼0.3 nm with 1 ms time resolution and was restricted by detector saturation. To achieve higher localization precision, we designed and constructed an annular illumination total internal reflection dark-field microscopy system with an axicon lens, which can illuminate the AuNPs at high laser intensity without damaging the objective lens. In addition, we used high image magnification to avoid detector saturation. Consequently, we achieved 1.3 Å localization precision for 40 nm AuNPs and 1.9 Å localization precision for 30 nm AuNPs at 1 ms time resolution. Furthermore, even at 33 µs time resolution, localization precisions at 5.4 Å for 40 nm AuNPs and at 1.7 nm for 30 nm AuNPs were achieved. We then observed motion of head of kinesin-1 labeled with AuNP at microsecond time resolution. Transition cycles of bound/unbound states and tethered diffusion of unbound head during stepping motion on microtubule were clearly captured with higher time resolution or smaller AuNP than those used in previous studies, indicating applicability to single-molecule imaging of biomolecular motors.