Minocycline prevents hypoxia-induced seizures.

Severe hypoxia induces seizures, which reduces ventilation and worsens the ictal state. It is a health threat to patients, particularly those with underlying hypoxic respiratory pathologies, which may be conducive to a sudden unexpected death in epilepsy (SUDEP). Recent studies provide evidence that brain microglia are involved with both respiratory and ictal processes. Here, we investigated the hypothesis that microglia could interact with hypoxia-induced seizures. To this end, we recorded electroencephalogram (EEG) and acute ventilatory responses to hypoxia (5% O2 in N2) in conscious, spontaneously breathing adult mice. We compared control vehicle pre-treated animals with those pre-treated with minocycline, an inhibitory modulator of microglial activation. First, we histologically confirmed that hypoxia activates microglia and that pre-treatment with minocycline blocks hypoxia-induced microglial activation. Then, we analyzed the effects of minocycline pre-treatment on ventilatory responses to hypoxia by plethysmography. Minocycline alone failed to affect respiratory variables in room air or the initial respiratory augmentation in hypoxia. The comparative results showed that hypoxia caused seizures, which were accompanied by the late phase ventilatory suppression in all but one minocycline pre-treated mouse. Compared to the vehicle pre-treated, the minocycline pre-treated mice showed a delayed occurrence of seizures. Further, minocycline pre-treated mice tended to resist post-ictal respiratory arrest. These results suggest that microglia are conducive to seizure activity in severe hypoxia. Thus, inhibition of microglial activation may help suppress or prevent hypoxia-induced ictal episodes.

A simple scoring model based on machine learning predicts intravenous immunoglobulin resistance in Kawasaki disease.

INTRODUCTION: In Kawasaki disease (KD), accurate prediction of intravenous immunoglobulin (IVIG) resistance is crucial to reduce a risk for developing coronary artery lesions. OBJECTIVE: To establish a simple scoring model predicting IVIG resistance in KD patients based on the machine learning model. METHODS: A retrospective cohort study of 1002 KD patients diagnosed at 12 facilities for 10 years, in which 22.7% were resistant to initial IVIG treatment. We performed machine learning with diverse models using 30 clinical variables at diagnosis in 801 and 201 cases for training and test datasets, respectively. SHAP was applied to identify the variables that influenced the prediction model. A scoring model was designed using the influential clinical variables based on the Shapley additive explanation results. RESULTS: Light gradient boosting machine model accurately predicted IVIG resistance (area under the receiver operating characteristic curve (AUC), 0.78; sensitivity, 0.50; specificity, 0.88). Next, using top three influential features (days of illness at initial therapy, serum levels of C-reactive protein, and total cholesterol), we designed a simple scoring system. In spite of its simplicity, it predicted IVIG resistance (AUC, 0.72; sensitivity, 0.49; specificity, 0.82) as accurately as machine learning models. Moreover, accuracy of our scoring system with three clinical features was almost identical to that of Gunma score with seven clinical features (AUC, 0.73; sensitivity, 0.53; specificity, 0.83), a well-known logistic regression scoring model. CONCLUSION: A simple scoring system based on the findings in machine learning seems to be a useful tool to accurately predict IVIG resistance in KD patients.

Role of microglia in blood pressure and respiratory responses to acute hypoxic exposure in rats.

Microglia modulate cardiorespiratory activities during chronic hypoxia. It has not been clarified whether microglia are involved in the cardiorespiratory responses to acute hypoxia. Here we investigated this issue by comparing cardiorespiratory responses to two levels of acute hypoxia (13% O2 for 4 min and 7% O2 for 5 min) in conscious unrestrained rats before and after systemic injection of minocycline (MINO), an inhibitor of microglia activation. MINO increased blood pressure but not lung ventilation in the control normoxic condition. Acute hypoxia stimulated cardiorespiratory responses in MINO-untreated rats. MINO failed to significantly affect the magnitude of hypoxia-induced blood pressure elevation. In contrast, MINO tended to suppress the ventilatory responses to hypoxia. We conclude that microglia differentially affect cardiorespiratory regulation depending on the level of blood oxygenation. Microglia suppressively contribute to blood pressure regulation in normoxia but help maintain ventilatory augmentation in hypoxia, which underscores the dichotomy of central regulatory pathways for both systems.

Dual orexin receptor blocker suvorexant attenuates hypercapnic ventilatory augmentation in mice.

Suvorexant (Belsomra(R)), a dual orexin receptor antagonist widely used in the treatment of insomnia, inhibits the arousal system in the brain. However, the drug's ventilatory effects have not been fully explored. This study aims to investigate the expression of orexin receptors in respiratory neurons and the effects of suvorexant on ventilation. Immunohistology of brainstem orexin receptor OX2R expression was performed in adult mice (n = 4) in (1) rostral ventral respiratory group (rVRG) neurons projecting to the phrenic nucleus (PhN) retrogradely labeled by Fluoro-Gold (FG) tracer, (2) neurons immunoreactive for paired like homeobox 2b (Phox2b) in the parafacial respiratory group/retrotrapezoid nucleus (pFRG/RTN), and (3) neurons immunoreactive for neurokinin 1 receptor (NK1R) and somatostatin (SST) in the preBötzinger complex (preBötC). Additionally, we measured in vivo ventilatory responses to hyperoxic hypercapnia (5% CO2) and hypoxia (10% O2) before and after suvorexant pretreatment (10 and cumulative 100 mg/kg) in unrestrained mice (n = 10) in a body plethysmograph. We found the OX2R immunoreactive materials in pFRG/RTN Phox2b and preBötC NK1R/SST immunoreactive neurons but not in FG-labeled rVRG neurons, which suggests the involvement of orexin in respiratory control. Further, suvorexant expressly suppressed the hypercapnic ventilatory augmentation, otherwise unaffecting ventilation. Central orexin is involved in shaping the hypercapnic ventilatory chemosensitivity. Suppression of hypercapnic ventilatory augmentation by the orexin receptor antagonist suvorexant calls for caution in its use in pathologies that may progress to hypercapnic respiratory failure, or sleep-disordered breathing. Clinical trials are required to explore the role of targeted pharmacological inhibition of orexin in ventilatory pathologies.

Activation of Astrocytes in the Persistence of Post-hypoxic Respiratory Augmentation.

Acute hypoxia increases ventilation. After cessation of hypoxia loading, ventilation decreases but remains above the pre-exposure baseline level for a time. However, the mechanism of this post-hypoxic persistent respiratory augmentation (PHRA), which is a short-term potentiation of breathing, has not been elucidated. We aimed to test the hypothesis that astrocytes are involved in PHRA. To this end, we investigated hypoxic ventilatory responses by whole-body plethysmography in unanesthetized adult mice. The animals breathed room air, hypoxic gas mixture (7% O2, 93% N2) for 2min, and again room air for 10min before and after i.p. administration of low (100mg/kg) and high (300mg/kg) doses of arundic acid (AA), an astrocyte inhibitor. AA suppressed PHRA, with the high dose decreasing ventilation below the pre-hypoxic level. Further, we investigated the role of the astrocytic TRPA1 channel, a putative ventilatory hypoxia sensor, in PHRA using astrocyte-specific Trpa1 knockout (asTrpa1 -/-) and floxed Trpa1 (Trpa1 f/f) mice. In both Trpa1 f/f and asTrpa1 -/- mice, PHRA was noticeable, indicating that the astrocyte TRPA1 channel was not directly involved in PHRA. Taken together, these results indicate that astrocytes mediate the PHRA by mechanisms other than TRPA1 channels that are engaged in hypoxia sensing.

Prevention Measures for COVID-19 and Changes in Kawasaki Disease Incidence.

BACKGROUND: Kawasaki disease is suspected to be triggered by previous infection. The prevention measures for coronavirus disease 2019 (COVID-19) have reportedly reduced transmission of certain infectious diseases. Under these circumstances, the prevention measures for COVID-19 may reduce the incidence of Kawasaki disease. METHODS: We conducted a retrospective study using registration datasets of patients with Kawasaki disease who were diagnosed in all 11 inpatient pediatric facilities in Yamanashi Prefecture. The eligible cases were 595 cases that were diagnosed before the COVID-19 pandemic (from January 2015 through February 2020) and 38 cases that were diagnosed during the COVID-19 pandemic (from March through November 2020). Incidence of several infectious disease were evaluated using data from the Infectious Disease Weekly Report conducted by the National Institute of Infectious Diseases. RESULTS: Epidemics of various infectious diseases generally remained at low levels during the first 9 months (March through November 2020) of the COVID-19 pandemic. Moreover, the incidence of COVID-19 was 50-80 times lower than the incidence in European countries and the United States. The total number of 38 cases with Kawasaki disease for the 9 months during the COVID-19 pandemic was 46.3% (-3.5 standard deviations [SDs] of the average [82.0; SD, 12.7 cases] for the corresponding 9 months of the previous 5 years. None of the 38 cases was determined to be triggered by COVID-19 based on their medical histories and negative results of severe acute respiratory syndrome coronavirus 2 testing at admission. CONCLUSION: These observations provide a new epidemiological evidence for the notion that Kawasaki disease is triggered by major infectious diseases in children.

Apparent Life-Threatening Event in an Infant with SARS-CoV-2 Infection.

The 2019 novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global outbreak of infection. In general, children with coronavirus disease-2019 have been reported to show milder respiratory symptoms than adult patients. Here, we have described a case of a SARS-CoV-2-infected infant who presented to our hospital with a severe episode of an apparent life-threatening event (ALTE). An 8-month-old, otherwise healthy female infant presented to our hospital because of a sudden cardiopulmonary arrest. Approximately 1 h before this episode, the patient showed no symptoms, except a worse humor than usual. On arrival at our hospital, the patient had severe acidosis, but there were no clear signs of inflammatory response. Chest computed tomography showed weak consolidations in the upper right lung and atelectasis in the lower left lung. No signs of congenital heart disease or cardiomyopathy were observed on echocardiography, and no significant arrhythmia was observed during the clinical course. However, SARS-CoV-2 RNA was detected by real-time reverse transcription polymerase chain reaction in tracheal aspirate and urine samples. Although the assessment of further similar cases is indispensable, this case suggests that SARS-CoV-2 infection may be an underlying factor in the pathophysiology of ALTE.

Structural and functional connectivity from the dorsomedial hypothalamus to the ventral medulla as a chronological amplifier of sympathetic outflow.

Psychological stress activates the hypothalamus, augments the sympathetic nervous output, and elevates blood pressure via excitation of the ventral medullary cardiovascular regions. However, anatomical and functional connectivity from the hypothalamus to the ventral medullary cardiovascular regions has not been fully elucidated. We investigated this issue by tract-tracing and functional imaging in rats. Retrograde tracing revealed the rostral ventrolateral medulla was innervated by neurons in the ipsilateral dorsomedial hypothalamus (DMH). Anterograde tracing showed DMH neurons projected to the ventral medullary cardiovascular regions with axon terminals in contiguity with tyrosine hydroxylase-immunoreactive neurons. By voltage-sensitive dye imaging, dynamics of ventral medullary activation evoked by electrical stimulation of the DMH were analyzed in the diencephalon-lower brainstem-spinal cord preparation of rats. Although the activation of the ventral medulla induced by single pulse stimulation of the DMH was brief, tetanic stimulation caused activation of the DMH sustained into the post-stimulus phase, resulting in delayed recovery. We suggest that prolonged excitation of the DMH, which is triggered by tetanic electrical stimulation and could also be triggered by psychological stress in a real life, induces further prolonged excitation of the medullary cardiovascular networks, and could contribute to the pathological elevation of blood pressure. The connectivity from the DMH to the medullary cardiovascular networks serves as a chronological amplifier of stress-induced sympathetic excitation. This notion will be the anatomical and pathophysiological basis to understand the mechanisms of stress-induced sustained augmentation of sympathetic activity.

Right Pulmonary Vein Atresia in a Mildly Symptomatic Boy: Comprehensive Analysis of Flow Dynamics Using Non-contrast-enhanced 4D Flow MR Imaging.

We present multimodal imaging in the rare case of isolated unilateral pulmonary vein atresia in a 6 year-old boy, including analysis of hemodynamics by magnetic resonance acquisition technique of time-resolved three-dimensional phase contrast imaging (4D flow magnetic resonance imaging). This novel imaging method enables the quantification and especially comprehensive visualization of blood flow patterns, even in complex congenital anomalies which abducted detailed assessment so far, and therefore constitutes a promising alternative to conventional vascular imaging techniques.

Plasma Exchange Downregulates Activated Monocytes and Restores Regulatory T Cells in Kawasaki Disease.

In Kawasaki disease (KD), the effect of plasma exchange (PE) on immune cells has not been fully elucidated. Therefore, we examined the changes in the number of CD14+ CD16+ activated monocytes, regulatory T (Treg ), and T-helper type 17 (Th17) cells in KD patients treated with PE. The percentage of total monocytes and subclasses of lymphocytes, including CD4+ and CD8+ T cells, and CD19+ B cells, showed no significant difference before and after PE. However, the percentage of CD14+ CD16+ monocytes in total leukocytes decreased significantly after PE (1.1% ± 1.5% vs. 2.1% ± 2.3%, P < 0.05). Furthermore, while the percentage of Th17 cells in CD4+ T cells did not change, the percentage of Treg cells in CD4+ T cells increased significantly after PE (11.1% ± 5.1% vs. 8.0% ± 4.4%, P < 0.05). Therefore, PE downregulates activated monocytes and upregulates Treg cells toward normal levels and thus attenuates inflammation in KD.

Electrical storm in an infant with short-coupled variant of torsade de pointes.

A 10-month-old infant experienced cardiac arrest caused by ventricular fibrillation (VF). His electrocardiogram (ECG) at rest was within the normal range. Amiodarone was indispensable due to its refractoriness to defibrillation. After implantable cardioverter defibrillator (ICD) implantation, ICD shock was delivered. ICD recordings documented VF and ventricular tachycardia (VT) triggered by premature ventricular contractions with an extremely short coupling interval (240 ms), which were controlled by verapamil. To the best of our knowledge, our case is the first infant with ScTdP. As the electrical storm with ScTdP occurs unpredictably, it can be a cause of sudden infant death syndrome.

Infliximab regulates monocytes and regulatory T cells in Kawasaki disease.

BACKGROUND: The effect of infliximab (IFX) on immune cells has not been fully reported in Kawasaki disease (KD). To investigate the mechanism of IFX in KD, we examined changes in the abundance of CD14+ CD16+ activated monocytes, regulatory T cells (Treg ) cells, and T-helper type 17 (Th17) cells following treatment with IFX. METHODS: We collected peripheral blood from patients with i.v. immunoglobulin (IVIG)-resistant KD and analyzed absolute CD14+ CD16+ monocyte, Treg (CD4+ CD25+ FOXP3+ ) and Th17 cell (CD4+ IL-17A+ ) counts on flow cytometry. We also measured changes in serum soluble interleukin (IL)-2 receptor (IL-2R), IL-6, and tumor necrosis factor (TNF)-α on enzyme-linked immunosorbent assay. RESULTS: Treg cells and Th17 cells significantly increased after IFX treatment compared with baseline (126 ± 85 cells/µL vs 62 ± 53 cells/µL, P < 0.01; 100 ± 111 cells/µL vs 28 ± 27 cells/µL, P < 0.05, respectively). In contrast, in a subgroup of patients with CD14+ CD16+ monocytes above the normal range before IFX, the CD14+ CD16+ monocytes significantly decreased following IFX treatment (72 ± 51 cells/µL vs 242 ± 156 cells/µL, P < 0.05).. Serum TNF-α did not change, but soluble IL-2R and IL-6 decreased after IFX treatment. CONCLUSION: IFX could downregulate activated monocytes and upregulate Treg cells towards the normal range. IFX treatment thus contributes to the process of attenuating inflammation in KD.

Benefits of Balloon-Dilatable Bilateral Pulmonary Artery Banding in Patients With Hypoplastic Left Heart Syndrome and Other Complex Cardiac Anomalies.

OBJECTIVES: The purpose of this study was to evaluate the potential of balloon-dilatable bilateral pulmonary artery banding (b-PAB) and its impact on the configuration of the pulmonary artery (PA). BACKGROUND: We have previously used balloon-dilatable b-PAB as first-stage palliation for patients with hypoplastic left heart syndrome (HLHS) and other complex cardiac anomalies. METHODS: Two pliable tapes were placed around each branch of the PA and tightened with 7-0 polypropylene sutures in a manner that allowed for the subsequent adjustment of PA diameters. We retrospectively examined the adjustability of PA diameters by balloon dilation and the need for surgical PA angioplasty at later stages. RESULTS: From January 2010 to October 2013, we performed b-PAB in 8 patients, including 3 borderline cases between biventricular repair (BVR) and univentricular repair (UVR). The b-PAB procedures were performed at a median age of 6.5 days (range, 2-10 days). Balloon dilations were performed in 10 lesions in 4 patients. All of the procedures were performed safely. Two patients reached definite BVR. The remaining 6 patients underwent open palliative procedures with univentricular physiologies that resulted in 2 deaths unrelated to the initial b-PAB. In all but 1 of the patients, the PA configuration was properly maintained and did not require surgical pulmonary angioplasty. CONCLUSIONS: Balloon-dilatable b-PAB can be performed safely and prevents PA distortion at later stages. This technique should be considered for patients with complex cardiac anomalies if uncertainty exists regarding the optimal surgical strategy (BVR or UVR) in early infancy.

Redox modulation of para-phenylenediamine by substituted nitronyl nitroxide groups and their spin states.

Three kinds of para-phenylenediamine (PDA) derivatives bearing nitronyl nitroxide (NN) groups were prepared and characterized on the basis of the electrochemical, electron spin resonance (ESR) spectroscopic, absorption spectroscopic, and magnetic susceptibility measurements. It was clarified that the oxidation potential of the central PDA unit is strongly influenced by the numbers of substituted electron-withdrawing NN groups. In addition, the intervalence charge transfer in the central PDA unit was detected in the monocationic states of the PDAs with two NN groups, indicating the coexistence of the localized spins and the delocalized spin on theses molecules. Moreover, pulsed ESR measurements confirmed that the delocalized spin on the central PDA unit and the localized two spins on the NN groups were ferromagnetically coupled in the monocationic states.