Developmental alterations of the spinal trigeminal nucleus disclosed by substance P immunohistochemistry in fetal and infant sudden unexplained deaths

Role of endothelial cells and angiotensin converting enzyme-II in COVID-19 and brain damages post-infection

Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) causes coronavirus disease 2019 (COVID-19), which became a pandemic in late 2019 and early 2020. Apart from many other symptoms of this infection, such as loss of smell and taste, rashes, body aches, fatigue, and psychological and cardiac symptoms, it also causes vasodilation in response to inflammation via nitric oxide release. SARS CoV-2 affects microcirculation, resulting in the swelling and damage of endothelial cells, micro thrombosis, constriction of capillaries, and damage to pericytes that are vital for the integrity of capillaries, angiogenesis, and the healing process. Cytokine storming has been associated with COVID-19 illness. Capillary damage and congestion may cause limited diffusion exchange of oxygen in the lungs and hence hypoxemia and tissue hypoxia occur. This perspective study will explore the involvement of capillary damage and inflammation by their interference with blood and tissue oxygenation as well as brain function in the persistent symptoms and severity of COVID-19. The overall effects of capillary damage due to COVID-19, microvascular damage, and hypoxia in vital organs are also discussed in this perspective. Once initiated, this vicious cycle causes inflammation due to hypoxia, resulting in limited capillary function, which in turn causes inflammation and tissue damage. Low oxygen levels and high cytokines in brain tissue may lead to brain damage. The after-effects may be in the form of psychological symptoms such as mood changes, anxiety, depression, and many others that need to be investigated.

Investigating genetic variants in microRNA regulators of Neurokinin-1 receptor in sudden infant death syndrome

Sudden infant death syndrome (SIDS) occurs more often in male than in female infants, suggesting involvement of the X-chromosome. Histopathological studies have suggested that altered expression of the Neurokinin-1 receptor may also play a role in the pathogenesis of SIDS. It was hypothesised that genetic variants in three X-chromosome-encoded microRNA (miRNA/miR), known to down-regulate expression of the Neurokinin-1 receptor, may contribute to SIDS.

AIM

To identify sequence variants in the miRNAs within a study cohort (27 cases of SIDS and 28 controls) and determine if there was a difference in the frequencies in male and female SIDS infants.

METHODS

Genomic DNA prepared from stored blood spots was amplified and sequenced to identify genetic variants in miR500A, miR500B and miR320D2.

RESULTS

No novel variants in the miRNAs were identified in our study cohort. We identified one known single-nucleotide polymorphism (SNP) in miR320D2: rs5907732 G/T, in both cases and controls. No significant difference in the SNP frequency was observed between male and female SIDS cases.

CONCLUSION

This pilot study suggests that sequence variants in three miRNAs do not contribute to the reported higher prevalence of SIDS in male infants and do not contribute to the pathogenesis of SIDS in our cohort.

The role of Substance P in the defense line of the respiratory tract and neurological manifestations post COVID-19 infection

Substance P (SP) has been a great interest for scientists due to its unique properties and involvement in various physiological and pathological phenomenon. It took almost a century for the current understanding of this peptide so far. Its role in brain and gut were initially discussed and later on it was widely studied and observed in cardiovascular system, asthma, traumatic brain injury, immune response, vasodilation, behavior, inflammation, arthritis, cancer, airway hyper responsiveness and respiratory disorders. Involvement of SP in sudden perinatal death and COVID-19 has also been discussed which shed light on its vital role in respiratory rhythm regulation and initiation of cytokine storming in COVID-19. This article will provide a comprehensive overview of the researches done to understand the basic functions and involvement of SP in different processes of cell and its association with various diseases. This article describes the historical and scientific journey of SP from its discovery until today, including its future perspectives.

Novel chemical-physical autopsy investigation in Sudden Infant Death and Sudden Intrauterine Unexplained Death Syndromes

Aim: Verify the presence of inorganic nanoparticle entities in brain tissue samples from Sudden Infant Death Syndrome (SIDS)/Sudden Intrauterine Unexplained Death Syndrome (SIUDS) cases. The presence of inorganic debris could be a cofactor that compromises proper brain tissue functionality. Materials & methods: A novel autopsy approach that consists of neuropathological analysis procedures combined with energy dispersive spectroscopy/field emission gun environmental scanning electron microscopy investigations was implemented on 10 SIDS/SIUDS cases, whereas control samples were obtained from 10 cases of fetal/infant death from known cause. Results: Developmental abnormalities of the brain were associated with the presence of foreign bodies. Although nanoparticles were present as well in control samples, they were not associated with histological brain anomalies, as was the case in SIDS/SIUDS. Conclusion: Inorganic particles present in brain tissues demonstrate their ability to cross the hemato-encephalic barrier and to interact with tissues and cells in an unknown yet pathological fashion. This gives a rationale to consider them as co-factors of lethality.

Substance P/ Neurokinin-1 Receptor, Trigeminal Ganglion, Latency, and Coronavirus Infection-Is There Any Link?

Novel Severe Acute Respiratory Syndrome-Corona Virus-2 infection (SARS-CoV-2) is an acute respiratory and infectious disease. This perspective aims to provide a basic understanding of the inflammation caused by SARS-CoV-2 and its relation to the trigeminal ganglion (TG). The virus enters through the mucous membranes of the orofacial region and reaches the TG, where it resides and takes control of its peptides including Substance P (SP). SP is the main neuropeptide, neuromodulator, and neuro-hormone of TG, associated with nociception and inflammation under noxious stimulus. SP release is triggered and, consequently, affects the immune cells and blood vessels to release the mediators for inflammation. Hence, cytokine storm is initiated and causes respiratory distress, bronchoconstriction, and death in complicated cases. Neurokinin-1 Receptor (NK-1R) is the receptor for SP and its antagonists, along with glucocorticoids, may be used to alleviate the symptoms and treat this infection by blocking this nociceptive pathway. SP seems to be the main culprit involved in the triggering of inflammatory pathways in SARS-CoV-2 infection. It may have a direct association with cardio-respiratory rhythm, sleep-wake cycle, nociception, and ventilatory responses and regulates many important physiological and pathological functions. Its over-secretion should be blocked by NK-1R antagonist. However, experimental work leading to clinical trials are mandatory for further confirmation. Here, it is further proposed that there is a possibility of latency in SARS-CoV-2 virus infection if it is acting through TG, which is the main site for other viruses that become latent.

Prognostic Significance of Substance P/Neurokinin 1 Receptor and Its Association with Hormonal Receptors in Breast Carcinoma

Expression and immunolocalization of Substance P (SP)/Neurokinin-1 Receptor (NK-1R) in breast carcinoma (BC) patients and its association with routine proliferative markers (ER, PR, HER2/neu, and Ki-67) were evaluated. A cross-sectional study was performed on 34 cases of BC. There were 23 cases of group A (grade III), 8 of group B (grade II), and only 3 cases of group C (grade I). All samples were then processed for SP and NK-1R immunohistochemistry for few cases. 14/23 cases (61%) of group A, 7/8 cases (88%) of group B, and 2/3 (67%) cases of group C were SP positive. Overall, strong staining (≥10% tumor cells), labeled as "+3," was observed in 9/14 (64.2%) cases of group A and 1/8 (12.5%) cases of group B. Moderate staining labelled as "+2" (in ≥10% tumor cells) was observed in 3/14 (21.4%) cases of group A and 4/8 (50%) cases of group B. Weak positive staining "+1" was observed in only 2/14 (14.28%) cases of group A, 2/8 (25%) cases of group B, and all 2/2 (100%) cases of group C. SP and NK-1R are overexpressed in breast carcinomas, and there is significant association between the grade of tumor and their overexpression.

Neurokinin-1 Receptor as a potential drug target for COVID-19 treatment

Novel Coronavirus infection (COVID-19) has become a pandemic in these days. It is an acute respiratory and infectious disease with no known etiology and treatment. It is continuously causing losses of precious lives and economy at a global scale on daily basis. It is the need of the hour to find more treatment strategies by either developing a drug or to boost the immune system. This opinion article aims to provide Substance P (SP) as a possible cause of the initiation of cytokine storm developed in COVID-19 infection and to suggest Neurokinin-1 Receptor (NK-1R) antagonist, Aprepitant, as a drug to be used for its treatment. This perspective will provide directions to the Biomedical scientists to explore SP and NK-1R and prepare a drug to alleviate the symptoms and cure the disease. It is very important to work on this perspective at earliest to reach to some conclusion regarding the therapeutic intervention. Clinical studies may also be conducted if proven successful. SP is a neurotransmitter and neuromodulator, released from the trigeminal nerve of brainstem as a result of nociception. It is directly related to the respiratory illness as in COVID-19 infection. It is responsible for the increased inflammation and the signature symptoms associated with this disease. It is the main switch that needs to be switched off by administering Aprepitant along with glucocorticosteroid, dexamethasone.

Protocol of controlled odorant stimulation for reducing apnoeic episodes in premature newborns: a randomised open-label Latin-square study with independent evaluation of the main endpoint (PREMODEUR)

INTRODUCTION

Apnoea affects 85% of premature infants under 34 weeks of age and would be an important risk factor for subsequent neuropsychological disorders. Currently, premature children with life-threatening apnoeas receive stimulants such as methylxanthines (mainly, caffeine) or doxapram (an analeptic unlicensed in children under 15). However, these products have undesirable effects (hyperarousal, irritability, sleep disorders, tachycardia) and are not always effective because apnoea does persist in some premature newborns. Previous studies have indicated that odorant stimulation, a non-invasive intervention, may stimulate the respiratory rhythm. The objective of the present protocol is to reduce the occurrence of apnoeic episodes in premature newborns by controlled odorant stimulation added to current pharmacological treatments.

METHODS AND ANALYSIS

The project is a randomised open-label Latin-square trial with independent evaluation of the main endpoint. It will include 60 preterm neonates from two university hospital neonatal intensive care units over 2 years (2021-2023). Each newborn will receive no (S0), sham (S1) or real olfactory stimulation (S2) in random order. During S2, three distinct odorants (mint, grapefruit and vanilla) will be delivered successively, in puffs, over 24 hours. Mint and grapefruit odours stimulate the main and the trigeminal olfactory pathways, whereas vanilla odour stimulates only the main olfactory pathway. A statistical analysis will compare the incidence of apnoeic episodes during S1 versus S2 using a mixed effects Poisson model.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Comité de Protection des Personnes Île-de-France XI (# 2017-AO13-50-53). The results will be disseminated through various scientific meetings, specialised peer-reviewed journals and, whenever possible, posted on appropriate public websites.

TRIAL REGISTRATION NUMBER

NCT02851979; Pre-results.

Comprehensive Analysis of Genes Associated With Sudden Infant Death Syndrome

Background: Sudden infant death syndrome (SIDS) is a tragic incident which remains a mystery even after post-mortem investigation and thorough researches. Methods: This comprehensive review is based on the genes reported in the molecular autopsy studies conducted on SIDS so far. A total of 20 original studies and 7 case reports were identified and included in this analysis. The genes identified in children or adults were not included. Most of the genes reported in these studies belonged to cardiac channel and cardiomyopathy. Cardiac channel genes in SIDS were scrutinized for further analysis. Results: After screening and removing the duplicates, 42 unique genes were extracted. When the location of these genes was assessed, it was observed that most of these belonged to Chromosomes 11, 1 and 3 in sequential manner. The pathway analysis shows that these genes are involved in the regulation of heart rate, action potential, cardiac muscle cell contraction and heart contraction. The protein-protein interaction network was also very big and highly interactive. SCN5A, CAV3, ALG10B, AKAP9 and many more were mainly found in these cases and were regulated by many transcription factors such as MYOG C2C1 and CBX3 HCT11. Micro RNA, "hsa-miR-133a-3p" was found to be prevalent in the targeted genes. Conclusions: Molecular and computational approaches are a step forward toward exploration of these sad demises. It is so far a new arena but seems promising to dig out the genetic cause of SIDS in the years to come.

Neuropathological explanation of minimal COVID-19 infection rate in newborns, infants and children - a mystery so far. New insight into the role of Substance P

Sars-Cov-2 or Novel coronavirus infection (COVID-19) has become a global challenge, affecting elderly population at large, causing a burden on hospitals. It has been affecting the world from a health and economic perspective after its emergence since October 2019 at Wuhan province of China. Later on it became a pandemic, with aged people most affected. Surprisingly, the infants and children were not severely infected and mortality among them was reported infrequently. If they died it was due to some comorbidity or congenital heart problems. Why the rate of infection varies in different age groups around the world and what is the protective mechanism in children remains a mystery.

Based on our neuropathological experience at the “Lino Rossi Research Center for the study and prevention of the unexpected perinatal death and Sudden Infant Death Syndrome (SIDS)” of the University of Milan, Italy, we hypothesize that the decreased severity of the disease in infants compared to the elderly may be due to alteration at neurotransmitter levels especially of the Substance P (SP) and of the spinal trigeminal nucleus in the brainstem that is responsible for its secretion.

This neurotransmitter may be directly related to the respiratory illness as is in COVID-19 infection. It is responsible for the increased inflammation and the characteristic symptoms associated with this disease. It is the main switch that must be urgently turned off using the NK-1R antagonist which is the receptor of SP and responsible for its functionality, especially in the elderly.

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COVID-19 is the biggest public health crisis of recent times.

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Children are not significantly affected in the same way as adults by COVID-19.

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The infant's immune system might protect from the ‘cytokine storm’ of adults.

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Increased expression of substance P in brains is here proposed as a possible cause.

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Aprepitant could be a promising therapeutic approach to COVID-19 infection in adults.

The retrotrapezoid nucleus and the neuromodulation of breathing

Breathing is regulated by a host of arousal and sleep-wake state-dependent neuromodulators to maintain respiratory homeostasis. Modulators such as acetylcholine, norepinephrine, histamine, serotonin (5-HT), adenosine triphosphate (ATP), substance P, somatostatin, bombesin, orexin, and leptin can serve complementary or off-setting functions depending on the target cell type and signaling mechanisms engaged. Abnormalities in any of these modulatory mechanisms can destabilize breathing, suggesting that modulatory mechanisms are not overly redundant but rather work in concert to maintain stable respiratory output. The present review focuses on the modulation of a specific cluster of neurons located in the ventral medullary surface, named retrotrapezoid nucleus, that are activated by changes in tissue CO₂/H⁺ and regulate several aspects of breathing, including inspiration and active expiration.

Immunohistochemical Expression of the Alpha Nicotinic Acetylcholine Receptor 7 in the Human Normal, Diabetic, and Preeclamptic Placenta and Products of Conception

Preeclampsia (PE) and gestational diabetes (GD) are complications in advanced pregnancy while miscarriage for early pregnancy. However, the etiological factors are not well understood. Smoking has been associated with these complications as well as the sudden intrauterine deaths, sudden infant death, miscarriages, and still births. However, the immunolocalization of alpha 7 nicotine acetylcholine receptor (α7-nAChR) is not studied. Materials and Methods: α7-nAChR subunit expression was evaluated in 10 paraffin-embedded placental tissues after delivery and 10 tissue samples of products of conception during first trimester by immunohistochemistry. Among the placental tissues, two samples were normal placental tissue, four from PE mother, and four from GD mother. The expression of α7-nAChR was compared between the two groups in general and within the subgroups of placenta as well. Protein expression was evaluated using the nuclear labeling index (%) of villi with positive cells stained, positive cells in the decidua, and intensity of staining in the outer villous trophoblast layer. Results: The expression of α7-nAChR protein was high in all the cases of placenta and products of conception (POCs). α7-nAChR expression showed no notable differences among different cases of miscarriages irrespective of the mother's age and gestational age at which the event occurred. However, there were some changes among the normal, PE, and GD placental groups in the linings of the blood vessels. Changes were restricted to the villi (as opposed to the decidua) lining cells, both cytotrophoblast and syncytiotrophoblast, and were specific to the α7 subunit. PE blood vessel lining was thicker and showed more expression of this receptor in endothelial cells and myofibroblasts in PE and GD groups. In POCs, the strong expression was observed in the decidua myocytes of maternal blood vessels and in syncytiotrophoblast and cytotrophoblast of chronic villi. Conclusion: Nicotine acetyl choline receptors are found to be expressed highly in the placental tissues and in products of conception. They may be associated with the sudden perinatal deaths and miscarriages or complications of pregnancy.

The Role of Maternal Smoking in Sudden Fetal and Infant Death Pathogenesis

Maternal smoking is a risk factor for both sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death syndrome (SIUDS). Both SIDS and SIUDS are more frequently observed in infants of smoking mothers. The global prevalence of smoking during pregnancy is 1.7% and up to 8.1% of women in Europe smoke during pregnancy and worldwide 250 million women smoke during pregnancy. Infants born to mothers who smoke have an abnormal response to hypoxia and hypercarbia and they also have reduced arousal responses. The harmful effects of tobacco smoke are mainly mediated by release of carbon monoxide and nicotine. Nicotine can enter the fetal circulation and affect multiple developing organs including the lungs, adrenal glands and the brain. Abnormalities in brainstem nuclei crucial to respiratory control, the cerebral cortex and the autonomic nervous system have been demonstrated. In addition, hypodevelopment of the intermediolateral nucleus in the spinal cord has been reported. It initiates episodic respiratory movements that facilitate lung development. Furthermore, abnormal maturation and transmitter levels in the carotid bodies have been described which would make infants more vulnerable to hypoxic challenges. Unfortunately, smoking cessation programs do not appear to have significantly reduced the number of pregnant women who smoke.

The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS)

Victims of sudden infant death syndrome (SIDS) are believed to have an underlying dysfunction in medullary homeostatic control that impairs critical responses to life threatening challenges such as hypoxia, hypercarbia and asphyxia, often during a sleep period. This failure is thought to result from abnormalities in a network of neural pathways in the medulla oblongata that control respiration, chemosensitivity, autonomic function and arousal. Studies have mainly focused on the role of serotonin, 5-hydroxytyptamine (5HT), although the neuropeptide substance P (SP) has also been shown to play an integral role in the modulation of medullary homeostatic function, often in conjunction with 5-HT. Actions of SP include regulation of respiratory rhythm generation, integration of cardiovascular control, modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may, therefore, also play a significant role in homeostatic dysfunction of the neurotransmitter network in SIDS. This review focuses on the pathways within the medulla involving SP and its tachykinin NK1 receptor, their potential relationship with the medullary 5-HT system, and possible involvement in the pathogenesis of SIDS.

Neurochemical Alterations in Sudden Unexplained Perinatal Deaths-A Review

Sudden unexpected perinatal collapse is a major trauma for the parents of victims. Sudden infant death syndrome (SIDS) is unexpected and mysterious death of an apparently healthy neonate from birth till 1 year of age without any known causes, even after thorough postmortem investigations. However, the incidence of sudden intrauterine unexplained death syndrome (SIUDS) is seven times higher as compared with SIDS. This observation is approximated 40-80%. Stillbirth is defined as death of a fetus after 20th week of gestation or just before delivery at full term without a known reason. Pakistan has the highest burden of stillbirth in the world. This basis of SIDS, SIUDS, and stillbirths eludes specialists. The purpose of this study is to investigate factors behind failure in control of these unexplained deaths and how research may go ahead with improved prospects. Animal models and physiological data demonstrate that sleep, arousal, and cardiorespiratory malfunctioning are abnormal mechanisms in SIUDS risk factors or in newborn children who subsequently die from SIDS. This review focuses on insights in neuropathology and mechanisms of SIDS and SIUDS in terms of different receptors involved in this major perinatal demise. Several studies conducted in the past decade have confirmed neuropathological and neurochemical anomalies related to serotonin transporter, substance P, acetylcholine α7 nicotine receptors, etc., in sudden unexplained fetal and infant deaths. There is need to focus more on research in this area to unveil the major curtain to neuroprotection by underlying mechanisms leading to such deaths.

Abnormalities in substance P neurokinin-1 receptor binding in key brainstem nuclei in sudden infant death syndrome related to prematurity and sex

Sudden infant death syndrome (SIDS) involves failure of arousal to potentially life threatening events, including hypoxia, during sleep. While neuronal dysfunction and abnormalities in neurotransmitter systems within the medulla oblongata have been implicated, the specific pathways associated with autonomic and cardiorespiratory failure are unknown. The neuropeptide substance P (SP) and its tachykinin neurokinin-1 receptor (NK1R) have been shown to play an integral role in the modulation of homeostatic function in the medulla, including regulation of respiratory rhythm generation, integration of cardiovascular control, and modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may therefore result in autonomic dysfunction during sleep and contribute to SIDS deaths. [¹²⁵I] Bolton Hunter SP autoradiography was used to map the distribution and density of the SP, NK1R to 13 specific nuclei intimately related to cardiorespiratory function and autonomic control in the human infant medulla of 55 SIDS and 21 control (non-SIDS) infants. Compared to controls, SIDS cases exhibited a differential, abnormal developmental profile of the SP/NK1R system in the medulla. Furthermore the study revealed significantly decreased NK1R binding within key medullary nuclei in SIDS cases, principally in the nucleus tractus solitarii (NTS) and all three subdivisions of the inferior portion of the olivo-cerebellar complex; the principal inferior olivary complex (PIO), medial accessory olive (MAO) and dorsal accessory olive (DAO). Altered NK1R binding was significantly influenced by prematurity and male sex, which may explain the increased risk of SIDS in premature and male infants. Abnormal NK1R binding in these medullary nuclei may contribute to the defective interaction of critical medullary mechanisms with cerebellar sites, resulting in an inability of a SIDS infant to illicit appropriate respiratory and motor responses to life threatening challenges during sleep. These observations support the concept that abnormalities in a multi-neurotransmitter network within key nuclei of the medullary homeostatic system may underlie the pathogenesis of a subset of SIDS cases.

Towards Better Understanding of the Pathogenesis of Neuronal Respiratory Network in Sudden Perinatal Death

Sudden perinatal death that includes the victims of sudden infant death syndrome, sudden intrauterine death syndrome, and stillbirth are heartbreaking events in the life of parents. Most of the studies about sudden perinatal death were reported from Italy, highlighting two main etiological factors: prone sleeping position and smoking. Other probable contributory factors are prematurity, male gender, lack of breastfeeding, respiratory tract infections, use of pacifiers, infant botulism, extensive use of pesticides and insecticides, etc. However, extensive studies across the world are required to establish the role of these factors in a different subset of populations. Previous studies confirmed the widely accepted hypothesis that neuropathology of the brainstem is one of the main cause of sudden perinatal death. This study is an effort to summarize the neuropathological evaluation of the brainstems and their association to sudden perinatal death. Brainstem nuclei in vulnerable infants undergo certain changes that may alter the sleep arousal cycle, cardiorespiratory control, and ultimately culminate in death. This review focuses on the roles of different brainstem nuclei, their pathologies, and the established facts in this regard in terms of it's link to such deaths. This study will also help to understand the role of brainstem nuclei in controlling the cardiorespiratory cycles in sudden perinatal death and may provide a better understanding to resolve the mystery of these deaths in future. It is also found that a global initiative to deal with perinatal death is required to facilitate the diagnosis and prevention in developed and as well as developing countries.

Substance P/Neurokinin 1 and Trigeminal System: A Possible Link to the Pathogenesis in Sudden Perinatal Deaths

Sudden demise of a healthy fetus or a neonate is a very tragic episode in the life of parents. These deaths have been a mystery since ages but still remain unexplained. This review proposes the involvement of trigeminal nerve, neurotransmitter substance P (SP), and its receptor neurokinin 1 (NK-1R) in regulation of cardiorespiratory control in fetuses and newborns. Anomalies and immaturity of neuroregulatory systems such as trigeminal system in medulla oblongata of brainstem may provide a possible mechanism of sudden perinatal deaths. Vulnerable infants are born with respiratory center immaturity which in combination with any stressor such as cold, hypoxia, and smoking may lead to cessation of breathing and ventilatory response. SP/NK-1R may be involved in regulating the ventilatory control in neonates while it is decreased in fetal and adult life in humans, and any alterations from these may lead to irreversible sleep apnea and fatal breathing, ultimately sudden death. This review summarizes the studies performed to highlight the expression of SP or NK-1R in sudden perinatal deaths and proposes the involvement of trigeminal ganglion along with its nerve and SP/NK-1R expression alteration as one of the possible pathophysiological underlying mechanism. However, further studies are required to explore the role of SP, NK-1R, and trigeminal system in the pathogenesis of sudden infant deaths, sudden intrauterine deaths, stillbirths, and sudden deaths later in human life.

Sudden Infant Death Syndrome - Role of Trigeminocardiac Reflex: A Review

Sudden infant death syndrome (SIDS) is an unexplained death in infants, which usually occurs during sleep. The cause of SIDS remains unknown and multifactorial. In this regard, the diving reflex (DR), a peripheral subtype of trigeminocardiac reflex (TCR), is also hypothesized as one of the possible mechanisms for this condition. The TCR is a well-established neurogenic reflex that manifests as bradycardia, hypotension, apnea, and gastric hypermotility. The TCR shares many similarities with the DR, which is a significant physiological adaptation to withstand hypoxia during apnea in many animal species including humans in clinical manifestation and mechanism of action. The DR is characterized by breath holding (apnea), bradycardia, and vasoconstriction, leading to increase in blood pressure. Several studies have described congenital anomalies of autonomic nervous system in the pathogenesis of SIDS such as hypoplasia, delayed neuronal maturation, or decreased neuronal density of arcuate nucleus, hypoplasia, and neuronal immaturity of the hypoglossal nucleus. The abnormalities of autonomic nervous system in SIDS may explain the role of TCR in this syndrome involving sympathetic and parasympathetic nervous system. We reviewed the available literature to identify the role of TCR in the etiopathogenesis of SIDS and the pathways and cellular mechanism involved in it. This synthesis will help to update our knowledge and improve our understanding about this mysterious, yet common condition and will open the door for further research in this field.

Apparent life-threatening events could be a wake-up call for sleep disordered breathing

INTRODUCTION

Polysomnographic recordings of children with an apparent life-threatening event (ALTE) have often displayed signs of partial or complete obstruction during sleep. Various studies have focused on facial dysmorphia in infants with ALTE and tried to establish a correlation between ALTE and obstructive sleep apnoea. Our study evaluates the phenotypic characteristics and the presence of sleep disorders in pre-school children who had at least one ALTE in the first year of life.

MATERIALS AND METHODS

We analyzed a group of pre-school children (mean age 5.21 ± 0.90 years) who were referred for an ALTE between 2008 and 2010. Children with no history of ALTEs were recruited as a control group. A detailed personal and family history was obtained for all the participants. Moreover, all the children underwent a general clinical examination and an ear, nose, and throat and orthodontic assessment. A clinical score was calculated according to the previously validated Sleep Clinical Record (SCR).

RESULTS

In the ALTE group (n = 107), snoring (25.2% vs. 6.1%), apnoeas (19.6% vs. 4.3%), restless sleep (31.7% vs. 6.1%), and habitual mouth breathing (35.5% vs. 12.2%, P < 0.05) were significantly more common (P < 0.05) than in the control group (n = 115). The ALTE group also displayed a higher frequency of Angle class II (27.1% vs. 15.7%, P < 0.05), narrow palate (72.9% vs. 51.3%, P < 0.05), and Friedman palate position (grades III-IV) (31.7% vs. 16.6%, P < 0.05) than the control group. Moreover, 38/107 (35.5%) children in the ALTE group had a positive SCR score compared with 14/115 controls (12.2%) (P < 0.05).

CONCLUSIONS

Pre-school age children with previous ALTE had a higher frequency of sleep disordered breathing and malocclusion phenotypes. The occurrence of ALTEs may be predictive of the development of sleep disordered breathing and highlight the importance of a long-term follow-up. Pediatr Pulmonol. 2016;51:1403-1408. © 2016 Wiley Periodicals, Inc.

Neurochemical abnormalities in the brainstem of the Sudden Infant Death Syndrome (SIDS)

The brainstem has been a focus in Sudden Infant Death Syndrome (SIDS) research for 30 years. Physiological and animal model data show that cardiorespiratory, sleep, and arousal mechanisms are abnormal after exposure to SIDS risk factors or in infants who subsequently die from SIDS. As the brainstem houses the regulatory centres for these functions, it is the most likely site to find abnormalities. True to this hypothesis, data derived over the last 30 years shows that the brainstem of infants who died from SIDS exhibits abnormalities in a number of major neurotransmitter and receptor systems including: catecholamines, neuropeptides, acetylcholinergic, indole amines (predominantly serotonin and its receptors), amino acids (predominantly glutamate), brain derived neurotrophic growth factor (BDNF), and some cytokines. A pattern is emerging of particular brainstem nuclei being consistently affected including the dorsal motor nucleus of the vagus (DMNV), nucleus of the solitary tract (NTS), arcuate nucleus (AN) and raphe. We discuss the implications of these findings and directions that this may lead in future research.

Role of neurotransmitter Substance P in progression of oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most frequent type of head and neck cancers.

OBJECTIVES

In the present study, we evaluated the expression and distribution of Substance P (SP) in different grades of OSCC and role of SP in its proliferation and progression.

SUBJECTS AND METHODS

Forty OSCC biopsies were immunohistochemically analyzed by using SP antibody, including 29 male and 11 female cases. 35% were well differentiated, 35% moderately differentiated and 30% poorly differentiated OSCC. The majority of patients were in the age range of 41-80 years. 62% of the cases were positive for SP. SP positivity was expressed in the cytoplasm of the tumor cells. Most of the positive cases were from the tongue region.

RESULTS

93% of moderately differentiated, 92% of poorly differentiated and 8% of well-differentiated carcinomas were SP-positive, but SP expression intensity was highest in poorly differentiated cases (+3). More positive patients were males (68.96% of all male patients) with moderately and poorly differentiated OSCC. Among all positive cases, 48% were poorly differentiated, 48% moderately differentiated and 4% well differentiated.

CONCLUSION

Strong expression of SP in poorly and moderately differentiated cases suggests a role of SP in the progression and development of tumor. Expression of SP in the current study increased as the proliferation of cells increased. Prevalence of oral cancer in males may be due to the fact that they smoke and use pan, chewing gum, beetle nut etc. in this region. SP antagonists can help in the reduction and inhibition of oral cancer. SP has a diagnostic value with sensitivity of 92.5% and specificity of 93.7%. The positive predictive value is 96.2% and the negative predictive value 88.2%.

Vulnerability of fourth ventricle choroid plexus in sudden unexplained fetal and infant death syndromes related to smoking mothers

The human choroid plexuses in the ventricular system represent the main source of cerebrospinal fluid secretion and constitute a major barrier interface that controls the brain's environment. The present study focused on the choroid plexus of the fourth ventricle, the main cavity of the brainstem containing important nuclei and/or structures mediating autonomic vital functions. In serial sections of 84 brainstems of subjects aged from 17 gestational weeks to 8 postnatal months of life, the deaths due to both known and unknown causes, we examined the cytoarchitecture and the developmental steps of the fourth ventricle choroid plexus to determine whether this structure shows morphological and/or functional alterations in unexplained perinatal deaths (Sudden Infant Death Syndrome and Sudden Intrauterine Unexplained Death Syndrome). High incidence of histological and immunohistochemical alterations (prevalence of epithelial dark cells, the presence of cystic cells in the stroma, decreased number of blood capillaries, hyperexpression of Substance P and apoptosis) were prevalently observed in unexplained death victims (p<0.05 vs. controls). A significant correlation was found between maternal smoking in pregnancy and choroidal neuropathological parameters (p<0.01). This work underscores the negative effects of prenatal exposure to nicotine on the development of the autonomic nervous system, and in particular of the fourth ventricle choroid plexus that is a very vulnerable structure in the developing CSF-brain system.

Neuronal nuclear antigen (NeuN): a useful marker of neuronal immaturity in sudden unexplained perinatal death

INTRODUCTION

In the developing brain neuronal differentiation is associated with permanent exit from the mitotic cycle. Neuronal nuclear antigen (NeuN) is a nuclear protein widely expressed in the mature postmitotic neurons.

METHODS

We applied NeuN immunocytochemistry in 65 cases of perinatal death (16 victims of sudden intrauterine unexplained death syndrome/SIUDS, 19 of sudden infant death syndrome/SIDS and 30 controls) to test the physiological status of the brain neurons. In addition we applied both TUNEL and Caspase 3 immunohistochemical methods in order to highlight a possible relation between decreased NeuN expression and apoptotic outcome. We also attempted to see whether or not NeuN pathological changes can be related to cigarette smoke absorption in pregnancy.

RESULTS

NeuN staining was considerably reduced or lost in SIUDS/SIDS compared to controls. However neurons with decreased NeuN-labeling showed no sign of apoptosis. A significant association was found between NeuN depletion and maternal smoking.

CONCLUSION

Altered NeuN expression can be a marker of immature and/or suffering neurons. The exclusive presence of this pattern of expression in SIUDS/SIDS victims, leads us to recommend the NeuN immunohistochemistry as a routine method in neuropathological protocols to convalidate a diagnosis of sudden perinatal death.