Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies.

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.

Comparison of flexible nasogastric tube and semi-rigid catheter during less invasive surfactant administration.

BACKGROUND: Various flexible and semi-rigid catheter techniques have been reported for surfactant delivery during less invasive surfactant administration (LISA) in preterm infants. Data on the effect of catheter selection on procedural success rates and adverse events are limited. Our objective was to compare the rates of success and adverse events of LISA performed with nasogastric tube and semi-rigid catheter. METHODS: This was a post-hoc analysis of data from a quality improvement project. LISA was performed according to the standardized local protocol. Baseline characteristics, data on performance of LISA, degree of difficulty in laryngoscopy and vital parameters after the initiation of LISA were collected and outcomes were compared between groups. RESULTS: Fifty-six infants were included (21 with nasogastric tube, and 35 with semi-rigid catheter). Procedure success rate (defined as a single LISA attempt resulting in intratracheal administration of the planned dose of surfactant), incidence of adverse events, heart rate and oxygen saturation values and outcomes did not differ significantly between the two groups. When using a nasogastric tube for LISA, a significantly higher fraction of inspired oxygen was needed in the 3rd (0.62 vs. 0.48, P=0.024), 4th (0.61 vs. 0.37, P<0.001) and 5th minute (0.48 vs. 0.37, P=0.001) to maintain normal oxygen saturations. CONCLUSIONS: Use of the semi-rigid catheter was associated with better oxygenation during and shortly after the procedure. Our results may help neonatal units to develop local guidelines.

[Trends in the management of respiratory distress syndrome in very preterm infants transferred to the Clinical Center of the University of Debrecen]. / A respirációs distressz szindróma kezelésének trendjei a Debreceni Egyetem Klinikai Központjába szállított igen éretlen koraszülöttekben.

INTRODUCTION: Although in utero transport is recommended in the case of threatening preterm delivery, it is not always possible. Management during postnatal transport may influence neonatal outcomes. OBJECTIVE: The aim of this study was to investigate the trends in patient characteristics, respiratory management and outcomes in very preterm infants requiring postnatal transfer between 2008 and 2021. METHOD: We conducted a retrospective study. Data were collected from both written and electronic medical records. Trends were assessed using joinpoint regression analysis and summarized as annual percentage changes (APC). RESULTS: A total of 177 infants were included. The number of transfers per year showed non-significant increase over time (APC = 6.8%, p = 0.087). The proportion of time above 60 minutes for care provided by the transport team at the referral site significantly increased (APC = 7.4%, p = 0.016). Between 2008 and 2010, the use of mechanical ventilation during transports increased (APC = 36.4%, p = 0.578), then it showed a decreasing trend during the rest of the study period (APC = -7.2%, p = 0.068). The use of oxygen concentrations above 40% significantly decreased (APC = -9.5%, p = 0.043). The proportion of surfactant doses less than 150 mg/kg showed a decreasing trend (APC = -7.65%, p = 0.162), while doses above 180 mg/kg significantly increased over time (APC = 8.5%, p = 0.031). Neonatal long-term outcome indicators showed improving trends. DISCUSSION: We observed relevant trends toward non-invasive approaches and improving outcomes. CONCLUSION: Our study can facilitate the ongoing change of approach to care during postnatal transport, promote the development of relevant protocols and guidelines, which together can improve the outcome of preterm infants born outside tertiary care centers. Orv Hetil. 2023; 164(15): 571-576.

Multicolored MIS-C, a single-centre cohort study.

BACKGROUND: The aim of this study was to investigate the clinical and laboratory parameters that can predict the severity of Multisystem Inflammatory Syndrome in Children (MIS-C) at admission. METHODS: We conducted a single-center, partly retrospective, partly prospective, observational cohort study between November 1, 2020 and December 31, 2021, which included patients aged from 1 month to 19 years, meeting the diagnostic criteria of MIS-C. We categorized the patients into three subgroups based on clinical and laboratory markers and assessed the predictive value of these factors in terms of ICU administration and cardiac abnormalities. RESULTS: 53 patients were classified in the following subgroups: Kawasaki-like disease (group 1) (47.2%, n = 25), shock with or without acute cardiac dysfunction (group 2) (32%, n = 17), fever and inflammation (group 3) (20.8%, n = 11). Subgroup analysis revealed that patients with shock and KD at initial presentation had significantly more severe manifestation of MIS-C requiring intensive care unit (ICU) treatment. Of the initial laboratory values, only CRP showed a significant difference between the 3 clinical groups, being lower in group 3. 52.6% of patients were admitted to the ICU. The median length of ICU stay was 3 days (range 3-20). ICU admission was more likely in patients with shortness of breath, renal failure (AKI) and patients with significantly increased concentrations of ferritin, D-dimer, INR and significantly milder increase concentration of fibrinogen. We found that fibrinogen and ferritin levels are independent risk factors for ICU admission. Cardiac abnormalities were found in 56.6% of total (30/53), with the following findings: decreased left ventricular function (32%), coronary abnormality (11.3%), pericardial effusion (17%), arrhythmia (32.1%) and mitral regurgitation (26.6%). Diarrhea and conjunctivitis at the initial presentation with significantly elevated CRP, Pro-BNP and blood pH concentrations were found to be a potential predisposing factor for decreased cardiac function while Pro-BNP and pH were independent risk factors for MIS-C. Regardless of the initial symptoms of MIS-C, the outcome was generally favorable. CONCLUSIONS: Clinical characteristics and baseline laboratory values ​​may help identify patients at increased risk for severe disease outcome, such as need for intensive care, presence of shock and decreased cardiac function. TRIAL REGISTRATION: Participation consent was not reqired and ethical considerations were unnecessary, since we did not perform any extra interventions, only the necessary and usual therapeutic and diagnostic methods were used.

Synchronized intermittent mandatory ventilation with volume guarantee and pressure support in neonates: Detailed analysis of ventilator parameters.

OBJECTIVE: To analyse the relationship between peak inflating pressure, expired tidal volume, respiratory rate, and inspiratory time of volume-guaranteed ventilator inflations and pressure-supported spontaneous breaths during synchronized intermittent positive pressure mode with volume guarantee and pressure support (SIMV-VG-PS) in neonates. METHODS: Ventilator parameters were downloaded every second from 16 babies ventilated with SIMV-VG-PS mode using Dräger Babylog VN500 ventilators over 137 days. Transcutaneous carbon dioxide (tcCO2 ) data were also collected. Data were computationally analysed using Python. The average of each ventilator parameter was determined during each minute separately for ventilator inflations and for spontaneous breaths. These values were compared and their effect on tcCO2 levels was also analysed. RESULTS: The relationship between the peak inflating pressure of the volume guaranteed inflations (PIPVG ) and pressure-supported spontaneous breaths (PIPPS ) was highly variable. The PIPPS /PIPVG ratio differed significantly from the value (0.66) targeted by clinicians (group median: 0.80, range: 0.50-1.00). PIPPS frequently exceeded PIPVG . When PIPPS /PIPVG was >0.66, the expired tidal volume and the rate of the pressure-supported spontaneous breaths were also significantly (p < 0.0001) higher, but there was no difference in tcCO2 levels. The flow-cycled spontaneous breaths had significantly shorter inspiratory times than ventilator inflations. CONCLUSIONS: During SIMV-VG-PS it is difficult to ensure a pressure support level proportionate to the inflating pressure of ventilator inflations and to achieve the stability of tidal volumes.

Incidence, predictors of success and outcome of LISA in very preterm infants.

OBJECTIVES: The aim of this study was to examine the success rate of less invasive surfactant administration (LISA), to identify early predictive factors for the outcome of LISA, and to compare neonatal outcomes between the LISA failure group and the group of infants who were successfully treated with LISA. DESIGN: A retrospective cohort study. PATIENTS: Infants born at less than 33 weeks of gestation (n = 158) and treated with LISA for respiratory distress syndrome. RESULTS: LISA was successful in 86 cases (54.4%); 72 preterm infants (45.6%) needed additional surfactant therapy and/or mechanical ventilation in the first 72 h (LISA failure). In a multivariate logistic regression analysis, six independent predictors of LISA success were identified: core temperature at the time of admission (adjusted odds ratio (OR): 3.56), dose of poractant alfa (<200 mg/kg; adjusted OR: 0.254), elevated C-reactive protein (>10 mg/L) at 24 h of life (adjusted OR: 0.28), highest respiratory severity score (RSS) during the first hour of life or at the time of LISA (adjusted OR: 0.463), maternal age (adjusted OR: 0.923), and birth weight (adjusted OR: 1.003). The receiver operating curve created by using the identified factors indicates good predictive power with an area under the curve of 0.85. LISA failure was associated with a substantially higher risk of complications. CONCLUSION: LISA success can be predicted by variables available before the intervention. Failure of LISA is relatively frequent event in very preterm infants and is associated with adverse outcomes. Prevention of hypothermia during early stabilization and appropriate dosing of surfactant may increase LISA success rates and improve patient outcome.

A defect in KCa3.1 channel activity limits the ability of CD8+ T cells from cancer patients to infiltrate an adenosine-rich microenvironment.

The limited ability of cytotoxic T cells to infiltrate solid tumors hampers immune surveillance and the efficacy of immunotherapies in cancer. Adenosine accumulates in solid tumors and inhibits tumor-specific T cells. Adenosine inhibits T cell motility through the A2A receptor (A2AR) and suppression of KCa3.1 channels. We conducted three-dimensional chemotaxis experiments to elucidate the effect of adenosine on the migration of peripheral blood CD8+ T cells from head and neck squamous cell carcinoma (HNSCC) patients. The chemotaxis of HNSCC CD8+ T cells was reduced in the presence of adenosine, and the effect was greater on HNSCC CD8+ T cells than on healthy donor (HD) CD8+ T cells. This response correlated with the inability of CD8+ T cells to infiltrate tumors. The effect of adenosine was mimicked by an A2AR agonist and prevented by an A2AR antagonist. We found no differences in A2AR expression, 3',5'-cyclic adenosine monophosphate abundance, or protein kinase A type 1 activity between HNSCC and HD CD8+ T cells. We instead detected a decrease in KCa3.1 channel activity, but not expression, in HNSCC CD8+ T cells. Activation of KCa3.1 channels by 1-EBIO restored the ability of HNSCC CD8+ T cells to chemotax in the presence of adenosine. Our data highlight the mechanism underlying the increased sensitivity of HNSCC CD8+ T cells to adenosine and the potential therapeutic benefit of KCa3.1 channel activators, which could increase infiltration of these T cells into tumors.

The C-terminal HRET sequence of Kv1.3 regulates gating rather than targeting of Kv1.3 to the plasma membrane.

Kv1.3 channels are expressed in several cell types including immune cells, such as T lymphocytes. The targeting of Kv1.3 to the plasma membrane is essential for T cell clonal expansion and assumed to be guided by the C-terminus of the channel. Using two point mutants of Kv1.3 with remarkably different features compared to the wild-type Kv1.3 (A413V and H399K having fast inactivation kinetics and tetraethylammonium-insensitivity, respectively) we showed that both Kv1.3 channel variants target to the membrane when the C-terminus was truncated right after the conserved HRET sequence and produce currents identical to those with a full-length C-terminus. The truncation before the HRET sequence (NOHRET channels) resulted in reduced membrane-targeting but non-functional phenotypes. NOHRET channels did not display gating currents, and coexpression with wild-type Kv1.3 did not rescue the NOHRET-A413V phenotype, no heteromeric current was observed. Interestingly, mutants of wild-type Kv1.3 lacking HRET(E) (deletion) or substituted with five alanines for the HRET(E) motif expressed current indistinguishable from the wild-type. These results demonstrate that the C-terminal region of Kv1.3 immediately proximal to the S6 helix is required for the activation gating and conduction, whereas the presence of the distal region of the C-terminus is not exclusively required for trafficking of Kv1.3 to the plasma membrane.

Sterol Regulation of Voltage-Gated K+ Channels.

Cholesterol is an essential lipid building block of the cellular plasma membrane. In addition to its structural role, it regulates the fluidity and raft structure of the membrane and influences the course of numerous membrane-linked signaling pathways and the function of transmembrane proteins, including ion channels. This is supported by a vast body of scientific data, which demonstrates the modulation of ion channels with a great variety of ion selectivity, gating, and tissue distribution by changes in membrane cholesterol. Here, we review what is currently known about the modulation of voltage-gated K+ (Kv) channels by changes in membrane cholesterol content, considering raft association of the channels, the roles of cholesterol recognition sites, and those of adaptor proteins in cholesterol-Kv channel interactions. We specifically focus on Kv1.3, the dominant K+ channel of human T cells. Effects of cholesterol depletion and enrichment and 7-dehydrocholesterol enrichment on Kv1.3 gating are discussed in the context of the immunological synapse and the comparison of the in vitro effects of sterol modifications on Kv1.3 function with ex vivo effects on cells from hypercholesterolemic and Smith-Lemli-Opitz patients.

7DHC-induced changes of Kv1.3 operation contributes to modified T cell function in Smith-Lemli-Opitz syndrome.

In vitro manipulation of membrane sterol level affects the regulation of ion channels and consequently certain cellular functions; however, a comprehensive study that confirms the pathophysiological significance of these results is missing. The malfunction of 7-dehydrocholesterol (7DHC) reductase in Smith-Lemli-Opitz syndrome (SLOS) leads to the elevation of the 7-dehydrocholesterol level in the plasma membrane. T lymphocytes were isolated from SLOS patients to assess the effect of the in vivo altered membrane sterol composition on the operation of the voltage-gated Kv1.3 channel and the ion channel-dependent mitogenic responses. We found that the kinetic and equilibrium parameters of Kv1.3 activation changed in SLOS cells. Identical changes in Kv1.3 operation were observed when control/healthy T cells were loaded with 7DHC. Removal of the putative sterol binding sites on Kv1.3 resulted in a phenotype that was not influenced by the elevation in membrane sterol level. Functional assays exhibited impaired activation and proliferation rate of T cells probably partially due to the modified Kv1.3 operation. We concluded that the altered membrane sterol composition hindered the operation of Kv1.3 as well as the ion channel-controlled T cell functions.

The anti-proliferative effect of cation channel blockers in T lymphocytes depends on the strength of mitogenic stimulation.

Ion channels are crucially important for the activation and proliferation of T lymphocytes, and thus, for the function of the immune system. Previous studies on the effects of channel blockers on T cell proliferation reported variable effectiveness due to differing experimental systems. Therefore our aim was to investigate how the strength of the mitogenic stimulation influences the efficiency of cation channel blockers in inhibiting activation, cytokine secretion and proliferation of T cells under standardized conditions. Human peripheral blood lymphocytes were activated via monoclonal antibodies targeting the TCR-CD3 complex and the co-stimulator CD28. We applied the blockers of Kv1.3 (Anuroctoxin), KCa3.1 (TRAM-34) and CRAC (2-Apb) channels of T cells either alone or in combination with rapamycin, the inhibitor of the mammalian target of rapamycin (mTOR). Five days after the stimulation ELISA and flow cytometric measurements were performed to determine IL-10 and IFN-γ secretion, cellular viability and proliferation. Our results showed that ion channel blockers and rapamycin inhibit IL-10 and IFN-γ secretion and cell division in a dose-dependent manner. Simultaneous application of the blockers for each channel along with rapamycin was the most effective, indicating synergy among the various activation pathways. Upon increasing the extent of mitogenic stimulation the anti-proliferative effect of the ion channel blockers diminished. This phenomenon may be important in understanding the fine-tuning of T cell activation.

Isolation, chemical and functional characterization of several new K(+)-channel blocking peptides from the venom of the scorpion Centruroides tecomanus.

Six new peptides were isolated from the venom of the Mexican scorpion Centruroides tecomanus; their primary structures were determined and the effects on ion channels were verified by patch-clamp experiments. Four are K(+)-channel blockers of the α-KTx family, containing 32 to 39 amino acid residues, cross-linked by three disulfide bonds. They all block Kv1.2 in nanomolar concentrations and show various degree of selectivity over Kv1.1, Kv1.3, Shaker and KCa3.1 channels. One peptide has 42 amino acids cross-linked by four disulfides; it blocks ERG-channels and belongs to the γ-KTx family. The sixth peptide has only 32 amino acid residues, three disulfide bonds and has no effect on the ion-channels assayed. It also does not have antimicrobial activity. Systematic numbers were assigned (time of elution on HPLC): α-KTx 10.4 (time 24.1); α-KTx 2.15 (time 26.2); α-KTx 2.16 (time 23.8); α-KTx 2.17 (time 26.7) and γ-KTx 1.9 (elution time 29.6). A partial proteomic analysis of the short chain basic peptides of this venom, which elutes on carboxy-methyl-cellulose column fractionation, is included. The pharmacological properties of the peptides described in this study may provide valuable tools for understanding the structure-function relationship of K(+) channel blocking scorpion toxins.

Analysis of the K+ current in human CD4+ T lymphocytes in hypercholesterolemic state.

Atherosclerosis involves immune mechanisms: T lymphocytes are found in atherosclerotic plaques, suggesting their activation during atherogenesis. The predominant voltage-gated potassium channel of T cells, Kv1.3 is a key regulator of the Ca(2+)-dependent activation pathway. In the present experiments we studied the proliferation capacity and functional changes of Kv1.3 channels in T cells from healthy and hypercholestaeremic patients. By means of CFSE-assay (carboxyfluorescein succinimidyl ester) we showed that spontaneous activation rate of lymphocytes in hypercholesterolemia was elevated and the antiCD3/antiCD28 co-stimulation was less effective as compared to the healthy group. Using whole-cell patch-clamping we obtained that the activation and deactivation kinetics of Kv1.3 channels were faster in hypercholesterolemic state but no change in other parameters of Kv1.3 were found (inactivation kinetics, steady-state activation, expression level). We suppose that incorporation of oxLDL species via its raft-rupturing effect can modify proliferative rate of T cells as well as the gating of Kv1.3 channels.