Structural Expansion of Catalytic RNA Nanostructures through Oligomerization of a Cyclic Trimer of Engineered Ribozymes.

The multimolecular assembly of three-dimensionally structured proteins forms their quaternary structures, some of which have high geometric symmetry. The size and complexity of protein quaternary structures often increase in a hierarchical manner, with simpler, smaller structures serving as units for larger quaternary structures. In this study, we exploited oligomerization of a ribozyme cyclic trimer to achieve larger ribozyme-based RNA assembly. By installing kissing loop (KL) interacting units to one-, two-, or three-unit RNA molecules in the ribozyme trimer, we constructed dimers, open-chain oligomers, and branched oligomers of ribozyme trimer units. One type of open-chain oligomer preferentially formed a closed tetramer containing 12 component RNAs to provide 12 ribozyme units. We also observed large assembly of ribozyme trimers, which reached 1000 nm in size.

Pneumonia Risk Increased by Dementia-Related Daily Living Difficulties: Poor Oral Hygiene and Dysphagia as Contributing Factors.

OBJECTIVE: Although pneumonia is the leading cause of death among patients with dementia, the specific underlying causes remain unclear. In particular, the potential connection between pneumonia risk and dementia-related daily living difficulties, such as oral hygiene practice and mobility impairment, and the use of physical restraint as a management practice, has not been extensively studied. METHODS: In our retrospective study, we included 454 admissions corresponding to 336 individual patients with dementia who were admitted to a neuropsychiatric unit due to behavioral and psychological symptoms. The admissions were divided into two groups: those who developed pneumonia while hospitalized (n=62) and those who did not (n=392). We investigated differences between the two groups in terms of dementia etiology, dementia severity, physical conditions, medical complications, medication, dementia-related difficulties in daily living, and physical restraint. To control potential confounding variables, we used mixed effects logistic regression analysis to identify risk factors for pneumonia in this cohort. RESULTS: Our study found that the development of pneumonia in patients with dementia was associated with poor oral hygiene, dysphagia, and loss of consciousness. Physical restraint and mobility impairment showed a weaker, nonsignificant association with the development of pneumonia. CONCLUSIONS: Our findings suggest that pneumonia in this population may be caused by two primary factors: increased pathogenic microorganisms in the oral cavity due to poor hygiene, and an inability to clear aspirated contents due to dysphagia and loss of consciousness. Further investigation is needed to clarify the relationship between physical restraint, mobility impairment, and pneumonia in this population.

Crucial differential diagnosis of rapidly progressive dementia: A case of leptomeningeal metastasis.

Background: Dementia that advances subacutely without accompanying neurological symptoms can often be misdiagnosed as a psychiatric condition. Leptomeningeal metastasis (LM), caused by the spread of malignant cells to the leptomeninges and the subarachnoid space, is a relatively unfamiliar condition to psychiatrists in this context. The diagnosis of LM remains challenging due to the scarcity of diagnostic tools possessing high sensitivity and specificity. Case Presentation: We present the clinical presentation of a male in his seventies with LM secondary to gastric ring cell carcinoma. The patient exhibited an acute confusional state, visual hallucinations, irritability, and cognitive impairments over a 3-week period. Initially, the patient was misdiagnosed with several conditions, including alcohol withdrawal syndrome, psychosis, and delirium associated with dementia, as there were no noteworthy findings on neurological examination or the head magnetic resonance imaging (MRI). Given the rapidly progressive cognitive decline, we maintained vigilance for potential neurological conditions, and a repeat investigation using head MRI and cerebrospinal fluid analysis led to the diagnosis of LM. Conclusion: This critical case report underscores the rarity of psychiatric-onset LM originating from gastric cancer and highlights the importance of comprehensive neurological evaluations.

Differentiating autoimmune encephalitis from schizophrenia spectrum disorders among patients with first-episode psychosis.

BACKGROUND: Although differential diagnosis between autoimmune encephalitis and schizophrenia spectrum disorders is crucial for a good outcome, the psychiatric symptoms that distinguish these two conditions have not been identified even though psychiatric symptoms are often the main manifestation of autoimmune encephalitis. Also, there are many situations in clinical psychiatry in which laboratory testing and imaging studies are not available. Because no comparative study of the psychiatric symptoms between these two conditions has been carried out, we explored diagnostically useful psychiatric symptoms in a retrospective case-control study. METHODS: We recruited 187 inpatients with first-episode psychosis who were admitted to our psychiatric unit and categorized them into two groups: the autoimmune encephalitis group (n = 10) and the schizophrenia spectrum disorders group (n = 177). Differences in the symptoms and signs between the two groups were investigated. RESULTS: Schneider's first-rank symptoms (e.g., verbal commenting hallucinations and delusional self-experience) were observed only in the schizophrenia spectrum disorders group, whereas altered perception was found more frequently in the autoimmune encephalitis group. Functional status was worse in the autoimmune encephalitis group, and neurological and neuropsychological signs were revealed almost exclusively in this group. A history of mental illness was more frequently reported in the schizophrenia spectrum disorders group than in the autoimmune encephalitis group. CONCLUSIONS: The psychiatric symptoms, i.e., Schneider's first-rank symptoms and altered perception, together with neurological and neuropsychological signs, functional status, and past history, may help clinicians accurately differentiate these two conditions among patients with first-episode psychosis.

Flexible Assembly of Engineered Tetrahymena Ribozymes Forming Polygonal RNA Nanostructures with Catalytic Ability.

Ribozymes with modular architecture constitute an attractive class of structural platforms for design and construction of nucleic acid nanostructures with biological functions. Through modular engineering of the Tetrahymena ribozyme, we have designed unit RNAs (L-RNAs), assembly of which formed ribozyme-based closed trimers and closed tetramers. Their catalytic activity was dependent on oligomer formation. In this study, the structural variety of L-RNA oligomers was extended by tuning their structural elements, yielding closed pentamers and closed hexamers. Their assembly properties were analyzed by electrophoretic mobility shift assay (EMSA) and atomic force microscopy (AFM).

"Case series: ischemic stroke associated with dehydration and arteriosclerosis in individuals with severe anorexia nervosa".

BACKGROUND: Numerous reports have indicated that patients with anorexia nervosa (AN) are at a relatively high risk of developing vascular diseases, including cardiovascular events and venous thromboembolism. However, there have been no previous reports of the development of ischemic stroke during refeeding therapy in patients with severe AN. This report is aimed at reporting the characteristics of an ischemic stroke in patients with AN. CASE PRESENTATIONS: Our study included 29 admissions by independent 19 female patients cases (19 patients), who received thorough medical, neurological, and psychiatric examinations. Two patients were diagnosed as having developed ischemic stroke; the first patient showed multiple infarctions in the brain, while the second showed symptomatic focal infarction. Our findings suggest that dehydration and arteriosclerosis, in association with severe malnutrition, could predispose to the development of ischemic stroke in patients with severe AN. CONCLUSIONS: Development of ischemic stroke in patients with AN might be overlooked. Watching out for neurological signs would help in early diagnosis of ischemic stroke in patients with AN during refeeding. Specific etiology could induce ischemic stroke in patients with AN even if they have no common risk factors of ischemia.

Surgically Diagnosed Primary Hepatic Angiosarcoma.

Primary hepatic angiosarcoma is a rare tumor originating from endothelial cells in the liver and accounts for approximately 1% of all hepatic malignant tumors. It is difficult to diagnose due to the lack of specific symptoms or tumor markers. No effective treatment exists, but complete surgical resection may achieve a good outcome. Since most primary hepatic angiosarcomas are already at an advanced stage at diagnosis, few reports describe tumors smaller than 2 cm. We report a case of surgery for a 1.7-cm sized primary hepatic angiosarcoma. Further studies are required to improve the preoperative diagnosis of primary hepatic angiosarcoma.

Programmable formation of catalytic RNA triangles and squares by assembling modular RNA enzymes.

RNA is a biopolymer that is attractive for constructing nano-scale objects with complex structures. Three-dimensional (3D) structures of naturally occurring RNAs often have modular architectures. The 3D structure of a group I (GI) ribozyme from Tetrahymena has a typical modular architecture, which can be separated into two structural modules (ΔP5 and P5abc). The fully active ribozyme can be reconstructed by assembling the two separately prepared modules through highly specific and strong assembly between ΔP5 ribozyme and P5abc RNA. Such non-covalent assembly of the two modules allows the design of polygonal RNA nano-structures. Through rational redesign of the parent GI ribozyme, we constructed variant GI ribozymes as unit RNAs for polygonal-shaped (closed) oligomers with catalytic activity. Programmed trimerization and tetramerization of the unit RNAs afforded catalytically active nano-sized RNA triangles and squares, the structures of which were directly observed by atomic force microscopy (AFM).