A case of Miller Fisher syndrome with delayed onset peripheral facial nerve palsy after COVID-19 vaccination: a case report.

BACKGROUND: To prevent the spread of the novel coronavirus disease 2019 (COVID-19) infection, various vaccines have been developed and used in a large number of people worldwide. One of the most commonly used vaccines is the mRNA vaccine developed by Moderna. Although several studies have shown this vaccine to be safe, the full extent of its side effects has not yet been known. Miller-Fisher syndrome (MFS) is a rare condition that manifests ophthalmoplegia, ataxia, and loss of tendon reflexes. It is a subtype of Guillain-Barré syndrome and an immune-mediated disease related to serum IgG anti-GQ1b antibodies. Several vaccines including those for COVID-19 have been reported to induce MFS. However, there have been no reports of MFS following Moderna COVID-19 vaccine administration. CASE PRESENTATION: A 70-year-old man was referred to our hospital due to diplopia that manifested 1 week after receiving the second Moderna vaccine dose. The patient presented with restricted abduction of both eyes, mild ataxia, and loss of tendon reflexes. He was diagnosed with MFS based on his neurological findings and detection of serum anti-GQ1b antibodies. The patient was administered intravenous immunoglobulin, and his symptoms gradually improved. Five days after admission, the patient showed peripheral facial paralysis on the right side. This symptom was suggested to be a delayed onset of peripheral facial nerve palsy following MFS that gradually improved by administration of steroids and antiviral drugs. CONCLUSION: There have been no previous reports of MFS after Moderna COVID-19 vaccination. This case may provide new information about the possible neurological side effects of COVID-19 vaccines.

Perception of genetic testing among patients with inherited retinal disease: Benefits and challenges in a Japanese population.

Inherited retinal disease (IRD) is clinically and genetically heterogeneous. Awareness of the importance of genetic testing for IRD in the clinical setting is increasing with the recent development of new therapeutic strategies, such as gene therapy. Here, the perception of genetic testing, including its benefits and potential challenges, among patients with IRD was investigated to establish strategies for IRD genetic testing and counseling practices that can meet the requirements of the patients in Japan. An anonymous self-administered questionnaire was distributed to 275 patients with IRD who underwent genetic testing after clinical consultation and genetic counseling to investigate the motivations for genetic testing, benefits, challenges, status of communication of results to family, and attitude to timing of genetic testing. In total, 228 (82.9%) responses were analyzed. Several major motivations for genetic testing were identified, including gaining information on future treatment options and clarification of the inheritance pattern, among others. No association was found between the sharing of results with family members and the results of genetic testing. Moreover, according to patients who received positive results, the benefits of genetic testing included information on the inheritance pattern, additional information on the diagnosis, and mental preparation for the future. Even patients who received negative or inconclusive (variant of uncertain significance) results reported certain informative and psychological benefits. Altogether, these findings suggest that provisions for genetic testing and genetic counseling are necessary within a certain period after clinical diagnosis and it is necessary to facilitate appropriate family communication about genetic testing results while paying attention to the background of family relationships. Moreover, the benefits of genetic testing can be influenced by the careful interpretation and information provided on the test results during genetic counseling and consultation.

Mother and son cases of Bickerstaff's brainstem encephalitis and fisher syndrome with serum anti-GQ1b IgG antibodies: a case report.

BACKGROUND: Bickerstaff's brainstem encephalitis (BBE) and Fisher syndrome (FS) are immune-mediated diseases associated with anti-ganglioside antibodies, specifically the anti-GQ1b IgG antibody. These two diseases potentially lie on a continuous spectrum with Guillain-Barré Syndrome (GBS). There are some reports of family cases of GBS and fewer of FS. However, there are no reports of family cases of BBE and FS. CASE PRESENTATION: We report a familial case of an 18-year-old son who had BBE and his 52-year-old mother diagnosed with FS within 10 days. The son showed impaired consciousness 1 week after presenting with upper respiratory symptoms and was brought to our hospital by his mother. He showed decreased tendon reflexes, limb ataxia, albuminocytologic dissociation in his spinal fluid, and positive serum anti-GQ1b antibodies. Haemophilus influenzae was cultured from his sputum. He was diagnosed with BBE and treated with intravenous immunoglobulin (IVIg) therapy, which led to an improvement in symptoms. The mother presented with upper respiratory symptoms 3 days after her son was hospitalized. Seven days later, she was admitted to the hospital with diplopia due to limited abduction of the left eye. She showed mild ataxia and decreased tendon reflexes. Her blood was positive for anti-GQ1b antibodies. She was diagnosed with FS and treated with IVIg, which also led to symptomatic improvement. CONCLUSIONS: There are no previous reports of familial cases of BBE and FS; therefore, this valuable case may contribute to the elucidation of the relationship between genetic predisposition and the pathogenesis of BBE and FS.

Ethical and professional challenges encountered by Japanese healthcare professionals who provide genetic counseling services.

It is important to identify ethical and professional challenges associated with genetic counseling services and systems to improve these services. In previous studies, specific challenges in genetic counseling were categorized into 16 domains. However, these studies were limited to a few countries, and genetic counseling differs according to national cultures or systems. Thus, additional efforts should be made to collect and analyze challenges in genetic counseling to address these issues. We interviewed 48 genetic counseling professionals in Japan (including 29 clinical geneticists, 17 genetic counselors, and 2 other professionals) about anecdotes that included ethical professional challenges. Thematic analysis was used to code the interview data, and anecdotes were categorized according to the ethical and professional challenges. The anecdotes (n = 333) were classified into the 16 previously identified domains and three unique subcategories: 'lack of understanding about genetic professionals or departments of genetic counseling by other professionals and patients', 'insufficient communication skills to carry out counseling on the part of the genetic counseling professionals', and 'lack of a system for self-improvement'. Many of the anecdotes also noted the emotional responses domain. The challenges experienced by Japanese genetic counseling professionals described herein will improve the quality of the service these professionals provide. Furthermore, the results can assist development of high-quality genetic counseling systems in countries developing these systems.

Truncating Variants Contribute to Hearing Loss and Severe Retinopathy in USH2A-Associated Retinitis Pigmentosa in Japanese Patients.

USH2A is a common causal gene of retinitis pigmentosa (RP), a progressive blinding disease due to retinal degeneration. Genetic alterations in USH2A can lead to two types of RP, non-syndromic and syndromic RP, which is called Usher syndrome, with impairments of vision and hearing. The complexity of the genotype-phenotype correlation in USH2A-associated RP (USH2A-RP) has been reported. Genetic and clinical characterization of USH2A-RP has not been performed in Japanese patients. In this study, genetic analyses were performed using targeted panel sequencing in 525 Japanese RP patients. Pathogenic variants of USH2A were identified in 36 of 525 (6.9%) patients and genetic features of USH2A-RP were characterized. Among 36 patients with USH2A-RP, 11 patients had syndromic RP with congenital hearing problems. Amino acid changes due to USH2A alterations were similarly located throughout entire regions of the USH2A protein structure in non-syndromic and syndromic RP cases. Notably, truncating variants were detected in all syndromic patients with a more severe retinal phenotype as compared to non-syndromic RP cases. Taken together, truncating variants could contribute to more serious functional and tissue damages in Japanese patients, suggesting important roles for truncating mutations in the pathogenesis of syndromic USH2A-RP.

Isotopic localization of the partially deuterated methyl group in solid methanol and methyl iodide.

Heat capacity measurements were made down to 0.35 K for the isotopic modifications of methanol, CH3-nDnOH, and methyl iodide, CH3-nDnI, (n = 0, 1, 2, 3) to determine the orientation of the partially deuterated methyl group in the solid phase. The mono-deuterated modifications favor the symmetric conformation, whereas the di-deuterated ones favor the asymmetric conformation. Infrared spectroscopy demonstrates that some vibrational modes change in intensity depending on temperature, which supports the energy scheme obtained by calorimetry. Zero-point kinetic energies were obtained by single molecule density functional theory calculations. Although the favorable conformations of CH2DOH and CHD2OH were confirmed, the energy difference between symmetric and asymmetric conformations was twice as large as that determined experimentally, which indicates that intermolecular forces significantly decrease the energy difference. For CHD2OH, the conversion between the two asymmetric conformations becomes very slow at low temperature and results in a residual entropy of R ln 2.

A novel mutation of PDE8B Gene in a Japanese family with autosomal-dominant striatal degeneration.

BACKGROUND: Autosomal-dominant striatal degeneration is a rare autosomal-dominant neurodegenerative movement disorder characterized by slowly progressive parkinsonism. Recently, a mutation of the cyclic nucleotide phosphodiesterase 8B gene was reported to be a causal gene mutation of this disease. METHODS: We report on the clinical characteristics of 2 patients of a Japanese family with autosomal-dominant striatal degeneration and the result of gene mutation analysis of this family. RESULTS: Clinical features of the patients are slowly progressive parkinsonism and brain MRI showing high signal intensity in T2-weighted images in the striatum. We found a heterozygous nonsense mutation in the first exon of cyclic nucleotide phosphodiesterase 8B gene, which is predicted to disrupt all important functional domains of the cyclic nucleotide phosphodiesterase 8B protein. CONCLUSIONS: This family is the second family with autosomal-dominant striatal degeneration after the first German family, confirming that cyclic nucleotide phosphodiesterase 8B gene is the causative gene for this disease.

Calorimetric measurements on Li4C60 and Na4C60.

We show specific heat data for Na4C60 and Li4C60 in the range 0.4-350 K for samples characterized by Raman spectroscopy and X-ray diffraction. At high temperatures, the two different polymer structures have very similar specific heats both in absolute values and in general trend. The specific heat data are compared with data for undoped polymeric and pristine C60. At high temperatures, a difference in specific heat between the intercalated and undoped C60 polymers of 100 J K(-1) mol(-1) is observed, in agreement with the Dulong-Petit law. At low temperatures, the specific heat data for Li4C60 and Na4C60 are modified by the stiffening of vibrational and librational molecular motion induced by the polymer bonds. The covalent twin bonds in Li4C60 affect these motions to a somewhat higher degree than the single intermolecular bonds in Na4C60. Below 1 K, the specific heats of both materials become linear in temperature, as expected from the effective dimensionality of the structure. The contribution to the total specific heat from the inserted metal ions can be well described by Einstein functions with TE = 386 K for Li4C60 and TE = 120 K for Na4C60, but for both materials we also observe a Schottky-type contribution corresponding to a first approximation to a two-level system with ΔE = 9.3 meV for Li4C60 and 3.1 meV for Na4C60, probably associated with jumps between closely spaced energy levels inside "octahedral-type" ionic sites. Static magnetic fields up to 9 T had very small effects on the specific heat below 10 K.

Bistable multifunctionality and switchable strong ferromagnetic-to-antiferromagnetic coupling in a one-dimensional rhodium(I)-semiquinonato complex.

We present a comprehensive study of the synthesis, heat capacity, crystal structures, UV-vis-NIR and mid-IR spectra, DFT calculations, and magnetic and electrical properties of a one-dimensional (1D) rhodium(I)-semiquinonato complex, [Rh(3,6-DBSQ-4,5-(MeO)2)(CO)2]∞ (3), where 3,6-DBSQ-4,5-(MeO)2(•-) represents 3,6-di-tert-butyl-4,5-dimethoxy-1,2-benzosemiquinonato radical anion. The compound 3 comprises neutral 1D chains of complex molecules stacked in a staggered arrangement with short Rh-Rh distances of 3.0796(4) and 3.1045(4) Å at 226 K and exhibits unprecedented bistable multifunctionality with respect to its magnetic and conductive properties in the temperature range of 228-207 K. The observed bistability results from the thermal hysteresis across a first-order phase transition, and the transition accompanies the exchange of the interchain C-H···O hydrogen-bond partners between the semiquinonato ligands. The strong overlaps of the complex molecules lead to unusually strong ferromagnetic interactions in the low-temperature (LT) phase. Furthermore, the magnetic interactions in the 1D chain drastically change from strongly ferromagnetic in the LT phase to antiferromagnetic in the room-temperature (RT) phase with hysteresis. In addition, the compound 3 exhibits long-range antiferromagnetic ordering between the ferromagnetic chains and spontaneous magnetization because of spin canting (canted antiferromagnetism) at a transition temperature T(N) of 14.2 K. The electrical conductivity of 3 at 300 K is 4.8 × 10(-4) S cm(-1), which is relatively high despite Rh not being in a mixed-valence state. The temperature dependence of electrical resistivity also exhibits a clear hysteresis across the first-order phase transition. Furthermore, the ferromagnetic LT phase can be easily stabilized up to RT by the application of a relatively weak applied pressure of 1.4 kbar, which reflects the bistable characteristics and demonstrates the simultaneous control of multifunctionality through external perturbation.

Spreading of amyotrophic lateral sclerosis lesions--multifocal hits and local propagation?

OBJECTIVE: To investigate whether or not the lesions in sporadic amyotrophic lateral sclerosis (ALS) originate from a single focal onset site and spread contiguously by prion-like cell-to-cell propagation in the rostrocaudal direction along the spinal cord, as has been hypothesised (the 'single seed and simple propagation' hypothesis). METHODS: Subjects included 36 patients with sporadic ALS and initial symptoms in the bulbar, respiratory or upper limb regions. Abnormal spontaneous activities in needle electromyography (nEMG)-that is, fibrillation potentials, positive sharp waves (Fib/PSWs) or fasciculation potentials (FPs)-were compared among the unilateral muscles innervated by different spinal segments, especially between the T10 and L5 paraspinal muscles, and between the vastus medialis and biceps femoris. Axon length and the proportion of muscle fibre types, which are both related to motoneuronal vulnerability in ALS, are similar in the paired muscles. RESULTS: Fourteen of 36 patients showed a non-contiguous distribution of nEMG abnormalities from the onset site, with skipping of intermediate segments. In eight of them, the non-contiguous pattern was evident between paired muscles with the same motoneuronal vulnerability. The non-contiguously affected lumbosacral lesions involved motoneuron columns horizontally or radially proximate to one another, appearing to form a cluster in four of the eight patients. FPs, known to precede Fib/PSWs, were shown more frequently than Fib/PSWs in all the lumbosacral segments but L5, suggesting that 2nd hits occur at L5 and then spread to other lumbosacral segments. CONCLUSIONS: In sporadic ALS, the distribution of lower motoneuron involvement cannot be explained by the 'single seed and simple propagation' hypothesis alone. We propose a 'multifocal hits and local propagation' hypothesis instead.

Two-dimensional solid-state topochemical reactions of 10,12-pentacosadiyn-1-ol adsorbed on graphite.

The photoinduced topochemical reaction of the diacetylene (DA) compound 10,12-pentacosadiyn-1-ol in the two-dimensional (2D) crystal phase adsorbed on graphite was examined by scanning tunneling microscopy (STM). The reaction efficiency and the structure of the generated polydiacetylene depend on its polymorphic forms, i.e., the "herringbone" or the "parallel" monomer arrangements. The reaction efficiency of the herringbone arrangement is lower than that of the parallel arrangement because the distance R between the probable reactant acetylenic carbon atoms of the herringbone arrangement is longer than that of the parallel arrangement. However, the fact that polydiacetylenes form from the herringbone arrangement (R = 0.58 nm) is contrary to the geometric criteria for the polymerization of three-dimensional (3D) crystals (the reaction was only observed if R < 0.4 nm). The polymerization criterion for the 2D phase differs from that of the 3D phase. In addition, the STM cross-section profiles of the polydiacetylenes reveal that the "lifted-up" and "in-plane" conformations form from the parallel and herringbone arrangements, respectively.

Cryptococcal meningitis accompanying lymphocytic inflammation predominantly in cerebral deep white matter: a possible manifestation of immune reconstitution inflammatory syndrome.

Cryptococcal meningitis is rarely complicated by immune-mediated leukoencephalopathy, but the precise pathomechanism is uncertain. A 72-year-old Japanese man treated with prednisolone for Sweet disease developed a subacute progression of meningitis, which was considered as neuro-Sweet disease. A treatment by methylprednisolone rapidly improved CSF findings with a remarkable decrease in lymphocyte numbers in the blood, but the patient's consciousness still worsened after the cessation of the treatment. The patient developed cryptococcal meningitis and MRI showed abnormal intensities predominantly in the cerebral deep white matter along with the recovery of lymphocyte numbers in the blood, which resulted in death. A postmortem examination of the brain revealed degenerative lesions, especially at the cerebral white matter and cortex adjacent to the leptomeninges abundantly infiltrated by Cryptococcus neoformans. In the affected cerebral deep white matter, perivascular infiltration of lymphocytes was prominent in coexistence with reactive astrocytes and vascular proliferation, but these findings were not observed in the subcortical and cortical lesions. Cryptococcus neoformans was not present within the brain parenchyma. This is the first report of a case suggesting that cryptococcal meningitis can accompany lymphocytic inflammation predominantly in cerebral deep white matter as a possible manifestation of immune reconstitution inflammatory syndrome.

Usefulness of thermography for differentiating Wallenberg's syndrome from noncentral vertigo in the acute phase.

OBJECTIVES: Wallenberg's syndrome (WS) is caused by a stroke in the lateral medulla and can present with various symptoms. One of the main symptoms is vertigo, which can be misdiagnosed as noncentral vertigo (NCV). Approximately 90% of the patients with acute WS have a lateral difference in body surface temperature (BST) due to autonomic pathway disturbances from infarction. Additionally, thermography can aid in WS diagnosis; however, whether BST differences occur in patients with acute NCV is unclear. METHODS: This study used thermography to measure the BST of patients with NCV and acute WS to determine the effectiveness of BST to differentiate between the conditions. Forty-eight consecutive patients diagnosed with NCV whose BST was measured using thermography during a hospital visit or admission were enrolled. The left and right BST of four sites (face, trunk, and upper and lower limbs) were measured and compared with obtained BST of nine patients with WS. RESULTS: Twenty-two patients had lateral differences in BST ≥ 0.5°C, three with ≥1.5°C, and none with ≥2.5°C. Only one patient with NCV had lateral differences in BST at two or more ipsilateral sites. When WS differentiated from NCV, a left-right difference ≥0.5°C in two or more ipsilateral sites had a sensitivity of 89% and specificity of 98%, and ≥1.0°C had a sensitivity of 78% and specificity of 98%. DISCUSSION: Acute WS can be differentiated from NCV through BST and the number of sites with lateral differences via thermography, even in rooms where conditions are unregulated.

High-sensitivity acceleration sensor detecting micro-mechanomyogram and deep learning approach for parkinson's disease classification.

High-sensitivity acceleration sensors have been independently developed by our research group to detect vibrations that are > 10 dB smaller than those detected by conventional commercial sensors. This study is the first to measure high-frequency micro-vibrations in muscle fibers, termed micro-mechanomyogram (MMG) in patients with Parkinson's disease (PwPD) using a high-sensitivity acceleration sensor. We specifically measured the extensor pollicis brevis muscle at the base of the thumb in PwPD and healthy controls (HC) and detected not only low-frequency MMG (< 15 Hz) but also micro-MMG (≥ 15 Hz), which was preciously undetectable using commercial acceleration sensors. Analysis revealed remarkable differences in the frequency characteristics of micro-MMG between PwPD and HC. Specifically, during muscle power output, the low-frequency MMG energy was greater in PwPD than in HC, while the micro-MMG energy was smaller in PwPD compared to HC. These results suggest that micro-MMG detected by the high-sensitivity acceleration sensor provides crucial information for distinguishing between PwPD and HC. Moreover, a deep learning model trained on both low-frequency MMG and micro-MMG achieved a high accuracy (92.19%) in classifying PwPD and HC, demonstrating the potential for a diagnostic system for PwPD using micro-MMG.

Clinical characteristics of patients with Parkinson's disease with reduced 123I-metaiodobenzylguanidine uptake in the major salivary glands and heart.

BACKGROUND: Parkinson's disease (PD) shows cardiac sympathetic denervation (SD) in 123I-metaiodobezylguanidine (MIBG) scintigraphy. Recently, SD in the major salivary glands (MSG-SD) was introduced as a possible radiological feature of PD. OBJECTIVE: To identify the clinical characteristics of patients with PD with reduced MSG and cardiac MIBG uptake (dual-SD) compared with those with reduced MSG or cardiac MIBG uptake only (single-SD). METHODS: We recruited 90 patients with PD and 30 controls and evaluated their non-motor (e.g., hyposmia, autonomic dysfunction) and motor (e.g., Movement Disorder Society-Unified Parkinson's Disease Rating Scale) features. We also assessed MIBG uptake in the MSG and heart using a quantitative semi-automatic method, and compared MIBG uptakes between PD and controls. We set cut-off values for optimal sensitivity and specificity, and compared the clinical characteristics of patients with PD between dual- and single-SD groups. RESULTS: MSG and cardiac MIBG uptakes were significantly reduced in PD. Sixty-one patients had dual-SD, 25 had single-SD, and four had non-SD. In patients with PD with normal cardiac SD, 76.5% (13/17) of whom showed abnormalities only in MSG-SD. When clinical characteristics were compared between the dual-SD and single-/non-SD groups, patients in the dual-SD group were older and had more severe hyposmia and autonomic dysfunction, except motor features. Multiple logistic regression analysis identified age as an important confounder. CONCLUSIONS: Patients with PD with dual-SD have more severe non-motor features than other patients. Autonomic dysfunction might progress independently from dopaminergic degeneration. Furthermore, our findings indicate that aging is a crucial factor in PD progression.

Copy number variant detection using next-generation sequencing in EYS-associated retinitis pigmentosa.

Retinitis pigmentosa (RP) is the most common inherited retinal dystrophy and a major cause of blindness. RP is caused by several variants of multiple genes, and genetic diagnosis by identifying these variants is important for optimizing treatment and estimating patient prognosis. Next-generation sequencing (NGS), which is currently widely used for diagnosis, is considered useful but is known to have limitations in detecting copy number variations (CNVs). In this study, we re-evaluated CNVs in EYS, the main causative gene of RP, identified via NGS using multiplex ligation-dependent probe amplification (MLPA). CNVs were identified in NGS samples of eight patients. To identify potential CNVs, MLPA was also performed on samples from 42 patients who were undiagnosed by NGS but carried one of the five major pathogenic variants reported in Japanese EYS-RP cases. All suspected CNVs based on NGS data in the eight patients were confirmed via MLPA. CNVs were found in 2 of the 42 NGS-undiagnosed RP cases. Furthermore, results showed that 121 of the 661 patients with RP had EYS as the causative gene, and 8.3% (10/121 patients with EYS-RP) had CNVs. Although NGS using the CNV calling criteria utilized in this study failed to identify CNVs in two cases, no false-positive results were detected. Collectively, these findings suggest that NGS is useful for CNV detection during clinical diagnosis of RP.

Hydration water and peptide dynamics--two sides of a coin. A neutron scattering and adiabatic calorimetry study at low hydration and cryogenic temperatures.

In the present work we bridge neutron scattering and calorimetry in the study of a low-hydration sample of a 15-residue hybrid peptide from cecropin and mellitin CA(1-7)M(2-9) of proven antimicrobial activity. Quasielastic and low-frequency inelastic neutron spectra were measured at defined hydration levels - a nominally 'dry' sample (specific residual hydration h = 0.060 g/g), a H2O-hydrated (h = 0.49) and a D2O-hydrated one (h = 0.51). Averaged mean square proton mobilities were derived over a large temperature range (50-300 K) and the vibrational density of states (VDOS) were evaluated for the hydrated samples. The heat capacity of the H2O-hydrated CA(1-7)M(2-9) peptide was measured by adiabatic calorimetry in the temperature range 5-300 K, for different hydration levels. The glass transition and water crystallization temperatures were derived in each case. The existence of different types of water was inferred and their amounts calculated. The heat capacities as obtained from direct calorimetric measurements were compared to the values derived from the neutron spectroscopy by way of integrating appropriately normalized VDOS functions. While there is remarkable agreement with respect to both temperature dependence and glass transition temperatures, the results also show that the VDOS derived part represents only a fraction of the total heat capacity obtained from calorimetry. Finally our results indicate that both hydration water and the peptide are involved in the experimentally observed transitions.

Electrochemical impedance measurement of a carbon nanotube probe electrode.

We measured and analyzed the electrochemical impedance of carbon nanotube (CNT) probe electrodes fabricated through the physical separation of insulated CNT bridges. The fabricated CNT electrodes were free-standing CNTs that were completely covered with an insulator, except for their tips. Typical dimensions of the nanoelectrodes were 1-10 nm in CNT diameter, 80-300 nm in insulator diameter, 0.5-4 µm in exposed CNT length and 1-10 µm in probe length. The electrochemical impedance at frequencies ranging from 40 Hz to 1 MHz was measured in physiological saline. The measured impedance of the CNT electrode was constant at 32 MΩ at frequencies below 1 kHz and was inversely proportional to frequency at frequencies above 10 kHz. By means of comparison with the parasitic capacitive impedance of the insulator membrane, we confirmed that the electrode was sufficiently insulated such that the measured constant impedance was given by the exposed CNT tip. Consequently, we can use the CNT electrode for highly localized electrochemical impedance measurements below 1 kHz. Considering an equivalent circuit and the nanoscopic dimensions of the CNT electrode, we demonstrated that the constant impedance was governed by diffusion impedance, whereas the solution resistance, charge-transfer resistance and double-layer capacitance were negligible.

LPA6-RhoA signals regulate junctional complexes for polarity and morphology establishment of maturation stage ameloblasts.

OBJECTIVES: Lysophosphatidic acid (LPA) is a potent bioactive phospholipid that exerts various functions upon binding to six known G protein-coupled receptors (LPA1-6); however; its role in a tooth remains unclear. This study aimed to explore the impact of the LPA/LPA receptor 6 (LPA6)/RhoA signaling axis on maturation stage ameloblasts (M-ABs), which are responsible for enamel mineralization. METHODS: The expression of LPA6 and LPA-producing synthetic enzymes during ameloblast differentiation was explored through immunobiological analysis of mouse incisors and molars. To elucidate the role of LPA6 in ameloblasts, incisors of LPA6 KO mice were analyzed. In vitro experiments using ameloblast cell lines were performed to validate the function of LPA-LPA6-RhoA signaling in ameloblasts. RESULTS: LPA6 and LPA-producing enzymes were strongly expressed in M-ABs. In LPA6 knockout mice, M-ABs exhibited abnormal morphology with the loss of cell polarity, and an abnormal enamel epithelium containing cyst-like structures was formed. Moreover, the expression of E-cadherin and zonula occludens-1 (ZO-1) significantly decreased in M-ABs. In vitro experiments demonstrated that LPA upregulated the expression of E-cadherin, ZO-1, and filamentous actin (F-actin) at the cellular membrane, whereas LPA6 knockdown decreased their expression and changed cell morphology. Furthermore, we showed that RhoA signaling mediates LPA-LPA6-induced junctional complexes. CONCLUSIONS: This study demonstrated that LPA-LPA6-RhoA signaling is essential for establishing proper cell morphology and polarity, via cell-cell junction and actin cytoskeleton expression and stability, of M-ABs. These results highlight the biological significance of bioactive lipids in a tooth, providing a novel molecular regulatory mechanism of ameloblasts.

Energy metabolic shift contributes to the phenotype modulation of maturation stage ameloblasts.

Maturation stage ameloblasts (M-ABs) are responsible for terminal enamel mineralization in teeth and undergo characteristic cyclic changes in both morphology and function between ruffle-ended ameloblasts (RA) and smooth-ended ameloblasts (SA). Energy metabolism has recently emerged as a potential regulator of cell differentiation and fate decisions; however, its implication in M-ABs remains unclear. To elucidate the relationship between M-ABs and energy metabolism, we examined the expression pattern of energy metabolic enzymes in M-ABs of mouse incisors. Further, using the HAT7 cell line with M-AB characteristics, we designed experiments to induce an energy metabolic shift by changes in oxygen concentration. We revealed that RA preferentially utilizes oxidative phosphorylation, whereas SA depends on glycolysis-dominant energy metabolism in mouse incisors. In HAT7 cells, hypoxia induced an energy metabolic shift toward a more glycolytic-dominant state, and the energy metabolic shift reduced alkaline phosphatase (ALP) activity and calcium transport and deposition with a change in calcium-related gene expression, implying a phenotype shift from RA to SA. Taken together, these results indicate that the energy metabolic state is an important determinant of the RA/SA phenotype in M-ABs. This study sheds light on the biological significance of energy metabolism in governing M-ABs, providing a novel molecular basis for understanding enamel mineralization and elucidating the pathogenesis of enamel hypomineralization.