Relevance of complement immunity with brain fog in patients with long COVID.

INTRODUCTION: This study aimed to elucidate the prevalence and clinical characteristics of patients with long COVID (coronavirus disease 2019), especially focusing on 50% hemolytic complement activity (CH50). METHODS: This retrospective observational study focused on patients who visited Okayama University Hospital (Japan) for the treatment of long COVID between February 2021 and March 2023. CH50 levels were measured using liposome immunometric assay (Autokit CH50 Assay, FUJIFILM Wako Pure Chemical Corporation, Japan); high CH50 was defined as ≥59 U/mL. Univariate analyses assessed differences in the clinical background, long COVID symptoms, inflammatory markers, and clinical scores of patients with normal and high CH50. Logistic regression model investigated the association between high CH50 levels and these factors. RESULTS: Of 659 patients who visited our hospital, 478 patients were included. Of these, 284 (59.4%) patients had high CH50 levels. Poor concentration was significantly more frequent in the high CH50 group (7.2% vs. 13.7%), whereas no differences were observed in other subjective symptoms (fatigue, headache, insomnia, dyspnea, tiredness, and brain fog). Multivariate analysis was performed on factors that could be associated with poor concentration, suggesting a significant relationship to high CH50 levels (adjusted odds ratio [aOR], 2.70; 95% confidence interval [CI], 1.33-5.49). Also, high CH50 was significantly associated with brain fog (aOR, 1.66; 95% CI, 1.04-2.66). CONCLUSIONS: High CH50 levels were frequently reported in individuals with long COVID, indicating a relationship with brain fog. Future in-depth research should examine the pathological role and causal link between complement immunity and the development of long COVID.

Ribosomal protein SA is a common component of neuronal intranuclear inclusions in polyglutamine diseases and Marinesco bodies.

Neuronal intranuclear inclusions (NIIs) are common key structures in polyglutamine (polyQ) diseases such as Huntington disease (HD), spinocerebellar ataxia type 1 (SCA1), and SCA3. Marinesco bodies (MBs) of dopaminergic neurons in the substantia nigra are also intranuclear structures and are frequently seen in normal elderly people. Ribosomal dysfunction is closely related to two differential processes; therefore, we aimed to identify the pathological characteristics of ribosomal protein SA (RPSA), a ribosomal protein, in both states. To this end, we evaluated the autopsy findings in four patients with HD, two SCA3, and five normal elderly cases (NCs). Immunohistochemical studies demonstrated that both NIIs and MBs contain RPSA. In polyQ diseases, RPSA was co-localized with polyQ aggregations, and 3D-reconstructed images revealed their mosaic-like distribution. Assessments of the organization of RPSA and p62 in NIIs showed that RPSA was more localized toward the center than p62 and that this unique organization was more evident in the MBs. Immunoblotting of the temporal cortices revealed that the nuclear fraction of HD patients contained more RPSA than that of NCs. In conclusion, our study revealed that RPSA is a common component of both NIIs and MBs, indicating that a similar mechanism contributes to the formation of polyQ NIIs and MBs.

Association between hypothalamic Alzheimer's disease pathology and body mass index: The Hisayama study.

The hypothalamus is the region of the brain that integrates the neuroendocrine system and whole-body metabolism. Patients with Alzheimer's disease (AD) have been reported to exhibit pathological changes in the hypothalamus, such as neurofibrillary tangles (NFTs) and amyloid plaques (APs). However, few studies have investigated whether hypothalamic AD pathology is associated with clinical factors. We investigated the association between AD-related pathological changes in the hypothalamus and clinical pictures using autopsied brain samples obtained from deceased residents of a Japanese community. A total of 85 autopsied brain samples were semi-quantitatively analyzed for AD pathology, including NFTs and APs. Our histopathological studies showed that several hypothalamic nuclei, such as the tuberomammillary nucleus (TBM) and lateral hypothalamic area (LHA), are vulnerable to AD pathologies. NFTs are observed in various neuropathological states, including normal cognitive cases, whereas APs are predominantly observed in AD. Regarding the association between hypothalamic AD pathologies and clinical factors, the degree of APs in the TBM and LHA was associated with a lower body mass index while alive, after adjusting for sex and age at death. However, we found no significant association between hypothalamic AD pathology and the prevalence of hypertension, diabetes, or dyslipidemia. Our study showed that a lower BMI, which is a poor prognostic factor of AD, might be associated with hypothalamic AP pathology and highlighted new insights regarding the disruption of the brain-whole body axis in AD.

Electrical pulse stimulation-induced tetanic exercise simulation increases the secretion of extracellular vesicles from C2C12 myotubes.

Extracellular vesicles (EVs) released into the blood during exercise mediate its whole-body health effects. The differentiation of EVs released by skeletal muscle cells in vivo from those released by other cells is challenging, therefore, it is unclear whether exercise increases the number of EVs secreted by skeletal muscle cells. In this study, we investigated whether exercise affects the quantity of EVs released from skeletal muscle cells using in vitro exercise models. C2C12 myotubes were cultured on a gel layer with 1 or 30 Hz electrical pulse stimulation (EPS) to induce contractions as an artificial simulating exercise. We found that tetanic contraction induced by 30 Hz EPS increased the number of secreted EVs. MicroRNA (miRNA)-seq analysis revealed that 30 Hz EPS altered the miRNA in the secreted EVs. Furthermore, expression analysis of genes related to the biogenesis and transport of EVs revealed that the expression of ALG-2 interacting protein X (Alix) was increased in response to 30 Hz EPS, and the peak value of intracellular Ca2+ in myotubes at 30 Hz EPS was higher than that at 1 Hz, indicating that the increase in intracellular Ca2+ concentration may be related to the increased secretion of EVs in response to 30 Hz EPS.

Super acute-onset disseminated BCG infection: A case report.

Intravesical Bacillus Calmette-Guérin (BCG) instillation is an established immunotherapy for superficial bladder cancer. Herein, we describe a case of disseminated BCG infection that developed immediately after the first BCG injection. A 76-year-old man diagnosed with non-invasive bladder cancer underwent intravesical BCG instillation; he developed high fever and systemic arthralgia later that night. General examination did not reveal any infectious sources, and a combination therapy of isoniazid, rifabutin, and ethambutol was initiated after collecting his blood, urine, bone marrow, and liver biopsy samples for mycobacterial cultures. Three weeks later, Mycobacterium bovis was detected in the urine and bone marrow samples, and pathological investigation of liver biopsy revealed multiple small epithelial granulomas with focal multinucleated giant cells, leading to a diagnosis of disseminated BCG infection. The patient recovered after long-term antimycobacterial therapy without remarkable sequelae. Most cases of disseminated BCG infection occur after several doses of BCG injections, and its onset reportedly varies among cases, ranging from a few days to several months. The present case was notable as disease onset was observed only a few hours after the first BCG injection. Although rare, development of disseminated BCG infection should be considered as a differential diagnosis in patients at any time after intravesical BCG instillation therapy.

Amyotrophic lateral sclerosis with TDP-43 abnormalities exhibiting globular glial tau inclusions in frontotemporal lobes and pallido-nigral system.

Here we present the autopsy case of an 80-year-old woman with a 9-year history of motor neuron disease and atypical Parkinsonism. Her initial symptom was gait disturbance, and she subsequently developed limb weakness and Parkinsonism without response to levodopa. Her motor symptoms progressed to bulbar palsy, and she died of respiratory failure. Postmortem examination revealed characteristic findings of amyotrophic lateral sclerosis (ALS), including motor neuronal loss with astrogliosis, corticospinal tract degeneration, and TAR DNA-binding protein of 43 kDa abnormalities, including nuclear loss and skein-like inclusions. In contrast, severe tau pathological changes were seen in the frontotemporal lobes and pallido-nigral system. Tau pathologies affected not only neuronal components, such as neurofibrillary tangles and neuropil threads, but also glial cells (astrocytes and oligodendrocytes). Some glial tau pathologies exhibited peculiar round accumulations, reminiscent of globular glial inclusions (GGIs) in globular glial tauopathy. This unique autopsy case demonstrates that ALS with TDP-43 could be comorbid with globular glial tau inclusions and indicates that common pathological mechanisms exist among ALS and GGI formation.

Case Series of Granulicatella Bacteremia: A Single-centered, Five-year Retrospective Study.

Granulicatella species are rare, nutritionally variant streptococci that cause infective endocarditis. Their clinical and microbiological characteristics remain unknown. We reviewed five years of Granulicatella cases in our hospital database (Jan 2017-Jun 2022), finding 6 Granulicatella adiacens cases and 1 Granulicatella elegans case. Clinical backgrounds and bacteremia sources were diverse; 3 cases developed polymicrobial bacteremia. Antimicrobial testing showed non-susceptibility to penicillin G in 4 of 7 cases (57.1%), and high susceptibility to carbapenems and vancomycin in all cases. Determining optimal antibiotic therapy for Granulicatella infections is vital in this era of antimicrobial resistance.

A Sulfur Containing Melanogenesis Substrate, N-Pr-4-S-CAP as a Potential Source for Selective Chemoimmunotherapy of Malignant Melanoma.

N-propionyl-4-S-cysteaminylphenol (N-Pr-4-S-CAP) is a substrate for tyrosinase, which is a melanin biosynthesis enzyme and has been shown to be selectively incorporated into melanoma cells. It was found to cause selective cytotoxicity against melanocytes and melanoma cells after selective incorporation, resulting in the induction of anti-melanoma immunity. However, the underlying mechanisms for the induction of anti-melanoma immunity remain unclear. This study aimed to elucidate the cellular mechanism for the induction of anti-melanoma immunity and clarify whether N-Pr-4-S-CAP administration could be a new immunotherapeutic approach against melanoma, including local recurrence and distant metastasis. A T cell depletion assay was used for the identification of the effector cells responsible for N-Pr-4-S-CAP-mediated anti-melanoma immunity. A cross-presentation assay was carried out by using N-Pr-4-S-CAP-treated B16-OVA melanoma-loaded bone marrow-derived dendritic cells (BMDCs) and OVA-specific T cells. Administration of N-Pr-4-S-CAP induced CD8+ T cell-dependent anti-melanoma immunity and inhibited the growth of challenged B16F1 melanoma cells, indicating that the administration of N-Pr-4-S-CAP can be a prophylactic therapy against recurrence and metastasis of melanoma. Moreover, intratumoral injection of N-Pr-4-S-CAP in combination with BMDCs augmented the tumor growth inhibition when compared with administration of N-Pr-4-S-CAP alone. BMDCs cross-presented a melanoma-specific antigen to CD8+ T cells through N-Pr-4-S-CAP-mediated melanoma cell death. Combination therapy using N-Pr-4-S-CAP and BMDCs elicited a superior anti-melanoma effect. These results suggest that the administration of N-Pr-4-S-CAP could be a new strategy for the prevention of local recurrence and distant metastasis of melanoma.

Trends in Long COVID Symptoms in Japanese Teenage Patients.

Background: Since the start of the global pandemic of coronavirus disease 2019 (COVID-19), not only adults but also many children have suffered from it. However, the clinical characteristics of long COVID in children remain unclear. Methods: In this retrospective observational study conducted in a single facility, we reviewed the medical records of all long COVID patients who visited Okayama University Hospital from February 2021 to October 2022, and we compared the clinical characteristics of long COVID in teenagers (11 to 18 years of age) with those in adults. Results: Data for 452 long COVID patients including 54 teenagers (11.9%) were analyzed. Fatigue was the most frequent symptom in teenagers (55.6% of the patients) and also in adults. On the other hand, the percentage of teenagers who complained of headache, which was the second most frequent complaint, was significantly higher than the percentage of adults (35.2% vs. 21.9%, p < 0.05). A comparison of the frequencies of symptoms depending on the viral variant showed that fatigue and headache were predominant symptoms in the Omicron variant phase. Of the 50 teenagers who were enrolled in schools, 28 (56.0%) could not attend school due to long COVID symptoms. The most common symptoms as reasons for absence from school were fatigue (85.7% of the patients), headache (42.9%), and insomnia (32.1%). Conclusions: Attention should be paid to the symptoms of fatigue and headache in teenagers with long COVID.

Screening of anti-atrophic peptides by using photo-cleavable peptide array and 96-well scale contractile human skeletal muscle atrophy models.

Skeletal muscle atrophy is characterized by decreases in protein content, myofiber diameter, and contractile force generation. As muscle atrophy worsens the quality of life, the development of anti-atrophic substances is desirable. In this study, we aimed to demonstrate a screening process for anti-atrophic peptides using photo-cleavable peptide array technology and human contractile atrophic muscle models. We developed a 96-well system and established a screening process with less variability. Dexamethasone-induced human atrophic tissue was constructed in the system. Eight peptides were selected from the literature and used for the screening of peptides for preventing the decrease of the contractile forces of tissues. The peptide QIGFIW, which showed preventive activity, was selected as the seed sequence. As a result of amino acid substitution, we obtained QIGFIQ as a peptide with higher anti-atrophic activity. These results indicate that the combinatorial use of the photo-cleavable peptide array technology and 96-well screening system could comprise a powerful approach to obtaining anti-atrophic peptides, and suggest that the 96-well screening system and atrophic model represent a practical and powerful tool for the development of drugs/functional food ingredients.

Persistent methicillin-resistant Staphylococcus aureus bacteremia in an adult patient with Netherton's syndrome: A case report.

Netherton's syndrome, a rare congenital disorder, is clinically characterized by chronic dermatologic disorders such as ichthyosiform erythroderma and ichthyosis linearis circumflexa. Curable treatment is yet to be established, and corticosteroid ointment is required to maintain good dermatological condition. Because of the permanent skin barrier impairment, patients with Netherton's syndrome are considered to be vulnerable to cutaneous infections. However, its clinical characteristics are yet to be elucidated due to the limited number of reported cases. Herein, we describe the clinical course of a patient who developed persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. A 19-year-old Japanese woman who had been diagnosed with Netherton's syndrome in her infancy and had been applying topical corticosteroid agents all over her body since her then, was referred to our hospital because of persistent MRSA bacteremia and secondary adrenal insufficiency. The patient was diagnosed with a central line-associated bloodstream infection and was appropriately treated with antibiotics and corticosteroid therapies. We assume that the damaged skin barrier due to the congenital dermatological disorder causes a disruption in the normal bacterial flora of the skin, leading to the invasion of harmful bacteria, such as S. aureus. In addition, internal (humoral immunodeficiency by decreased antibody against bacterial polysaccharide antigens) and external (prolonged and systemic use of corticosteroid ointment) factors bring about an immunodeficiency state in such patients. We highlight that in the absence of radical treatment, clinicians need to recognize that patients with Netherton's syndrome are vulnerable to bacterial infections owing to the mixture of immunosuppressive factors.

Clinical utility of urinary levels of catecholamines and their fraction ratios related to heart rate and thyroid function.

Urinary catecholamines (CAs) have been examined for the screening of pheochromocytomas. The decision to perform screening is based on symptoms suggesting secondary hypertension or hyperactivities of the sympathetic nervous system. To elucidate the usefulness of urinary fractions and ratios of CAs, 79 patients in whom 24-h excretions of urinary CAs including adrenaline (AD), noradrenaline (NA) and dopamine (DA) had been examined from 2015 until 2020 were retrospectively analyzed. There were no significant differences in urinary CA levels between two age groups, gender groups and two BMI groups. Patients with histories of preexisting hypertension and diabetes showed significantly higher levels of urinary NA excretion, and the urinary ratio of NA/DA was also increased in the patients with a history of hypertension. Heart rate (HR) was significantly correlated with the urinary ratio of NA/DA. Serum free thyroxine (FT4) concentration and ratio of FT4/thyrotropin (TSH) were correlated with the level of urinary AD. The levels of TSH and FT4/TSH showed negative and positive correlations, respectively, with the urinary NA/DA ratio. Thus, increases of HR are related to the enhanced conversion of DA to NA and increased thyroid hormones are involved in the increase in urinary AD and the conversion of DA to NA. History of lifestyle-related diseases and changes of HR and thyroid functions need to be considered for the evaluation of urinary CAs and their ratios.

Hormonal trends in patients suffering from long COVID symptoms.

Symptoms of long COVID are complex and long-lasting, and endocrine dysfunction might be involved in the underlying mechanisms. In this study, to clarify the hormonal characteristics of long COVID patients, laboratory data for patients who visited the outpatient clinic for long COVID were evaluated. A retrospective analysis was performed for patients who visited Okayama University Hospital during the period from Feb 2021 to Dec 2021 with focus on the interrelationships between major symptoms and endocrine data. Information and laboratory data were obtained from medical records for 186 patients. The patients had various symptoms, and the most frequent symptoms were general malaise, dysosmia/dysgeusia, hair loss, headache, dyspnea, and sleeplessness. Patients who were suffering from fatigue and dysosmia/dysgeusia were younger, while hair loss was more frequent in older and female patients. As for the characteristics of patients suffering from general fatigue, the scores of depression and fatigue were positively correlated with serum levels of cortisol and free thyroxin (FT4), respectively. Also, patients suffering from general fatigue had lower levels of serum growth hormone and higher levels of serum FT4, while patients with dysosmia/dysgeusia had a significantly lower level of serum cortisol. Serum thyrotropin (TSH) levels were higher and the ratios of FT4/TSH were lower in the initially severe cases, suggesting occult hypothyroidism. In addition, the ratios of plasma adrenocorticotropin to serum cortisol were decreased in patients with relatively high titers of serum SARS-CoV-2 antibody. Thus, hormonal changes seem to be, at least in part, involved in the persistent symptoms of long COVID.

Prevalence of medical factors related to aging among older car drivers: a multicenter, cross-sectional, descriptive study.

AIM: An increasing number of older adults in Japan are at an increased risk of road traffic crashes. This study aimed to investigate the prevalence of potential underlying medical factors that increase the risk of road traffic crashes among older people. METHODS: This cross-sectional observational study was conducted in 11 medical institutions in Japan using self-administered questionnaires and physical examination from January to May 2021. The background and social data, data on the use of nursing care insurance, and clinical data suggestive of polypharmacy, sarcopenia, cognitive impairment, and frailty/oral frailty were obtained. The prevalence of these factors was compared between everyday and occasional drivers. RESULTS: Data of 127 patients were collected; their median (interquartile range) age was 73 (70-78) years. Of the total participants, 82 were men (64.6%) and 45 were women (35.4%). There were 77 everyday drivers and 50 occasional drivers. Of these, 121 (95.3%) had not applied for nursing care insurance, but the numbers of those who required help 1 and 2 were 1 (0.8%) and 3 (2.4%), respectively. Prevalence of medical factors was as follows: polypharmacy, 27.6%; sarcopenia, 8.7%; dementia, 16.4%; frailty, 15.0%; and oral frailty, 54.3%; it was not significantly different between every day and occasional drivers. Intention to return the car license was significantly higher among the occasional drivers (2.6% vs. 14.0%; odds ratio: 6.7, 95% confidence interval: 1.2-70.6, p = 0.024). CONCLUSION: We uncovered the prevalence of medical factors that can be associated with road traffic crashes among Japanese older people aged ≥ 65 years in our community.

Analysis of plasmodesmata permeability using cultured tobacco BY-2 cells entrapped in microfluidic chips.

Plasmodesmata are unique channel structures in plants that link the fluid cytoplasm between adjacent cells. Plants have evolved these microchannels to allow trafficking of nutritious substances as well as regulatory factors for intercellular communication. However, tracking the behavior of plasmodesmata in real time is difficult because they are located inside tissues. Hence, a system was constructed to monitor the movement of substances by plasmodesmata using tobacco BY-2 cells, which are linearly organized cells, and a microfluidic device that traps them in place and facilitates observation. After targeting one cell for photobleaching, recovery of the lost H2B-GFP protein was detected within 200 min. No recovery was detected in that time frame by photobleaching the entire cell filaments. This suggested that the recovery of H2B-GFP protein was not due to de novo protein synthesis, but rather to translocation from neighboring cells. The transport of H2B-GFP protein was not observed when sodium chloride, a compound known to cause plasmodesmata closure, was present in the microfluid channel. Thus, using the microfluidic device and BY-2 cells, it was confirmed that the behavior of plasmodesmata could be observed in real time under controllable conditions.

Immunomodulation of Melanoma by Chemo-Thermo-Immunotherapy Using Conjugates of Melanogenesis Substrate NPrCAP and Magnetite Nanoparticles: A Review.

A major advance in drug discovery and targeted therapy directed at cancer cells may be achieved by the exploitation and immunomodulation of their unique biological properties. This review summarizes our efforts to develop novel chemo-thermo-immunotherapy (CTI therapy) by conjugating a melanogenesis substrate, N-propionyl cysteaminylphenol (NPrCAP: amine analog of tyrosine), with magnetite nanoparticles (MNP). In our approach, NPrCAP provides a unique drug delivery system (DDS) because of its selective incorporation into melanoma cells. It also functions as a melanoma-targeted therapeutic drug because of its production of highly reactive free radicals (melanoma-targeted chemotherapy). Moreover, the utilization of MNP is a platform to develop thermo-immunotherapy because of heat shock protein (HSP) expression upon heat generation in MNP by exposure to an alternating magnetic field (AMF). This comprehensive review covers experimental in vivo and in vitro mouse melanoma models and preliminary clinical trials with a limited number of advanced melanoma patients. We also discuss the future directions of CTI therapy.

Clinical Characteristics of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Diagnosed in Patients with Long COVID.

Background and Objectives: COVID-19 can be serious not only in the acute phase but also after the acute phase and some patients develop ME/CFS. There have been few studies on patients with long COVID in whom ME/CFS was diagnosed by physicians based on standardized criteria after examinations and exclusion diagnosis and not based on only subjective symptoms. The purpose of this study was to elucidate the detailed characteristics of ME/CFS in patients with long COVID. Materials and Methods: A retrospective descriptive study was performed for patients who visited a COVID-19 aftercare clinic established in Okayama University Hospital during the period was from February 2021 to April 2022. Results: Clinical data were obtained from medical records for 281 patients, and 279 patients who met the definition of long COVID were included. The overall prevalence rate of ME/CFS diagnosed by three sets of ME/CFS criteria (Fukuda, Canadian and IOM criteria) was 16.8% (48.9% in male and 51.1% in females). The most frequent symptoms in ME/CFS patients were general fatigue and post-exertional malaise (89.4% of the patients), headache (34.0%), insomnia (23.4%), dysosmia (21.3%) and dysgeusia (19.1%). Dizziness, chest pain, insomnia and headache were characteristic symptoms related to ME/CFS. The male to female ratio in ME/CFS patients was equal in the present study, although ME/CFS was generally more common in women in previous studies. Given that patients with ME/CFS had more severe conditions in the acute phase of COVID-19, the severity of the acute infectious state might be involved in the pathophysiology of ME/CFS. Conclusions: The prevalence rate of ME/CFS and the characteristic sequelae in the long COVID condition were revealed in this study.

Application of Kampo Medicines for Treatment of General Fatigue Due to Long COVID.

Evidence regarding treatment for the acute phase of COVID-19 has been accumulating, but specific treatment for long COVID/post-COVID-19 condition has not yet been established. Treatment with herbal medicine might be one treatment option for long COVID, but there has been little research on the effectiveness of herbal medicine for long COVID. The aim of this study was to clarify the prescription patterns of Kampo medicines, which are herbal medicines that originated in China and were developed in Japan, for the treatment of general fatigue due to long COVID. A retrospective descriptive study was performed for patients who visited a COVID-19 aftercare clinic established in Okayama University Hospital during the period from Feb 2021 to Dec 2021 with a focus on symptoms accompanying general fatigue and prescriptions of Kampo medicine. Among the clinical data obtained from medical records of 195 patients, clinical data for 102 patients with general fatigue and accompanying symptoms were analyzed. The patients had various symptoms, and the most frequent symptoms accompanying general fatigue were dysosmia, dysgeusia, headache, insomnia, dyspnea, and hair loss. Prescriptions of Kampo medicine accounted for 24.1% of the total prescriptions (n = 609). The most frequently prescribed Kampo medicine was hochuekkito (71.6%) and other prescribed Kampo medicines were tokishakuyakusan, ryokeijutsukanto, juzentaihoto, hangekobokuto, kakkonto, ninjin'yoeito, goreisan, rikkunshito, and keishibukuryogan. Since the pathophysiology of general fatigue after an infectious disease is, in general, considered a qi deficiency in Kampo medicine, treatments with such compensation agents can be the major prescription as a complement for the qi. In conclusion, Kampo medicine can be one of the main pharmacological treatments for long COVID accompanying general fatigue.

Transitional Changes in Fatigue-Related Symptoms Due to Long COVID: A Single-Center Retrospective Observational Study in Japan.

Background and Objectives: Changes in post COVID-19 condition (PCC) characteristics caused by viral variants have yet to be clarified. We aimed to characterize the differences between clinical backgrounds and manifestations in long COVID patients who were infected with the Delta variant and those who were infected with the Omicron variants. Materials and Methods: This study was a single-center retrospective observational study for patients who visited our COVID-19 aftercare outpatient clinic (CAC) established in Okayama University Hospital (Japan) during the period from 15 February 2021 to 15 July 2022. We classified the onset of COVID-19 in the patients into three groups, the preceding, Delta-dominant, and Omicron-dominant periods, based on the prevalent periods of the variants in our prefecture. Results: In a total of 353 patients, after excluding 8 patients, 110, 130, and 113 patients were classified into the preceding, Delta-dominant, and Omicron-dominant periods, respectively. Patients infected in the Omicron-dominant period had significantly fewer hospitalizations, milder illnesses, more vaccinations and earlier visit to the CAC than did patients infected in the Delta-dominant period. Patients infected in the Omicron-dominant period had significantly lower frequencies of dysosmia (12% vs. 45%, ** p < 0.01), dysgeusia (14% vs. 40%, ** p < 0.01) and hair loss (7% vs. 28%, ** p < 0.01) but had higher frequencies of fatigue (65% vs. 50%, * p < 0.05), insomnia (26% vs. 13%, * p < 0.05) and cough (20% vs. 7%, ** p < 0.01) than did patients infected in the Delta-dominant period. Conclusions: The transitional changes in long COVID symptoms caused by the two variants were characterized.

Screening of a novel free fatty acid receptor 1 (FFAR1) agonist peptide by phage display and machine learning based-amino acid substitution.

Free fatty acid receptor 1 (FFAR1 or GPR40) has attracted attention for the treatment of type 2 diabetes mellitus, and various small-molecule agonists have been developed. However, most FFAR1 agonists as well as endogenous ligands, such as linoleic acids, have high lipophilicity, and their high lipophilicity is related to off-target toxicity. Therefore, we need to focus on new ligand candidates with less toxicity. In this study, we screened peptides with FFAR1 agonist activity as new ligand candidates. First, we used phage display to identify peptides with high affinity to FFAR1. Next, the agonist activities of peptides determined by the phage display were evaluated by the TGF-α shedding assay. Finally, to improve the FFAR1 agonist activity of the peptide, we performed an inclusive single amino acid substitution and sequence analysis. Logistic regression (LR) analysis using 120 physiochemical properties was performed to predict peptides with high FFAR1 agonist activity. STTGTQY determined by phage display promoted glucose-stimulated insulin secretion in pancreatic MIN6 cells. Furthermore, STKGTF predicted by the LR analysis showed high insulin secretion at low concentrations compared to STTGTQY. The results of this study suggest that peptides could be new candidates as FFAR1 agonists.