Perinatal and infant early atherosclerotic coronary lesions

OBJECTIVE

Because the fetal origin of coronary artery lesions is controversial, early atherosclerotic coronary artery lesions in late fetal stillborns and infants, as well as the possible atherogenic role of maternal cigarette smoking, were studied.

METHODS

Twenty-two fetal death and 36 sudden infant death syndrome victims were examined by autopsy. In 28 of 58 cases, the mothers were smokers. Serially cut sections of coronary arteries were stained for light microscopy and immunotypified for CD68, CD34, alpha-smooth muscle actin, proliferating cell nuclear antigen, c-fos and apoptosis.

RESULTS

Multifocal coronary lesions were detected in 10 of 12 fetuses and in 15 of 16 infants whose mothers smoked. Arterial lesions in infants with nonsmoking mothers were observed in only five cases (two of 10 fetuses and three of 20 infants) (P<0.001). Alterations ranged from focal areas with mild myointimal thickening in prenatal life to early soft plaques in infants. Smooth muscle cells infiltrated into the subendothelium. These early lesions demonstrated c-fos gene activation in the smooth muscle cells of the media, and in some of these, positivity for apoptosis was observed, suggesting that c-fos overexpression may promote proliferation, as evidenced by proliferating cell nuclear antigen-positive cells.

CONCLUSIONS

Early intimal alterations of the coronary arteries are detectable in the prenatal and infancy period, and may be significantly associated with maternal smoking.

Genes regulating the serotonin metabolic pathway in the brain stem and their role in the etiopathogenesis of the sudden infant death syndrome

Genotypes and allelic frequencies of TPH2, 5-HTTLPR, the 5-HTT (SLC6A4) intron 2 variable-number tandem repeat (VNTR) region, and the MAOA VNTR region were determined in brain-stem samples of 20 "genuine" SIDS cases and compared with results obtained from 150 healthy controls. The SNP G1463A responsible for 80% functionality loss of TPH2 (tryptophan hydroxylase 2) was not detected, neither in SIDS infants nor in the controls. In contrast, a strict relation was found between the 5-HTTLPR genotype and its allelic frequencies with SIDS cases. The L/L genotype and the long allele (L) of the promoter region of the serotonin transporter were significantly associated (likelihood ratio (LR) test, p<0.001) with the syndrome (L/L, 60% SIDS vs 14% controls; L, 80% SIDS vs 42.6% controls). Polymorphisms of the intron 2 VNTR of the same gene showed a trend for significant differences between genotypes 10/10 and 12/12 (LR test, p=0.068), with the L-12 haplotype being almost twofold in SIDS (44.5%) with respect to controls (23.4%). Differences were even higher considering the genotype combination L/L-12/12 (20% SIDS vs 2.6%), and variations among categories were statistically highly significant (p<0.001). Although additional differences were observed in the frequency of the MAOA (monoamine oxidase A) VNTR genotype 3R/3R between SIDS and controls (respectively 15% vs 26%), the results were not supported by statistical significance. Molecular polymorphisms are discussed considering their functional role in regulating serotonin synthesis (TPH2), neuronal reuptake (5-HTTLPR and 5-HTT intron 2), and catabolism (MAOA) in the nervous system of Italian SIDS infants. Comparisons are made with previous data obtained in different ethnic groups.

Peripheral chemoreceptors: postnatal development and cytochemical findings in Sudden Infant Death Syndrome

The aim of the present study is to give a review of the postnatal development of peripheral chemoreceptors - carotid body, paraganglia, and pulmonary neuroendocrine cells (PNEC) - with implications in Sudden Infant Death Syndrome (SIDS). In the postnatal period, the hypoxic chemosensitivity of the carotid body gradually develops. Changes include proliferation of type I and II cells, increased numbers of dense core vesicles and K+ channels, and modifications of neurotransmitter/neuromodulator and receptor expression. Chromaffin paraganglia show increased expression of nitric oxide synthase and neuropeptides, and increased innervation. Innervation of PNEC develops fully only in the first postnatal period, after which their density falls. The neuropeptides produced by PNEC also changes, with increased expression of calcitonin gene-related peptide and neuropeptide YY and reduced expression of calcitonin and gastrin-releasing peptide. Most of the findings in the carotid body of SIDS victims, i.e., decrease in type I cells and dense cytoplasmic granules, and increase in progenitor cells, indicates immaturity of the carotid body, which may play a role in SIDS in the form of underlying biologic vulnerability. Aorticopulmonary paraganglia hyperplasia and increase of PNEC are also found in SIDS, and may be epiphenomena of alterations of the respiratory function with a pathogenetical role in SIDS. A comprehensive view of the pathogenesis of SIDS should also arise from the integration of peripheral chemoreceptors findings with neuro- and cardiopathologic ones.

Biopathology of the dentate-olivary complex in sudden unexplained perinatal death and sudden infant death syndrome related to maternal cigarette smoking

OBJECTIVES

The present study was aimed to evaluate the possible presence of cytohistologic and/or biologic modifications of the human dentate-olivary complex in sudden unexplained perinatal and infant deaths.

METHODS

We investigated the histologic morphology of the dentate and inferior olivary nuclei, the glial index, the c-fos and apoptotic immunopositivity, as well as the possible effects elicited by maternal cigarette smoking, in 44 cases of perinatal and infant death victims, aged from the 26th gestational week to 10 months of life.

RESULTS

We observed subtle alterations of both the medullary inferior olivary nucleus and of the cerebellar dentate nucleus, represented by a significant increase in the reactive astrocyte density and in the neuronal c-fos and apoptotic expression in unexplained death victims, compared with age-matched controls. These alterations were closely related to a maternal cigarette smoking habit.

DISCUSSION

We postulate that maternal smoking, besides inducing the previously demonstrated morpho-functional alterations of the autonomic central nervous system, could also exert an adverse influence on the dentate-olivary complex, leading to sudden death in vulnerable periods of perinatal development or early infancy.

Ontogenesis of human cerebellar cortex and biopathological characterization in sudden unexplained fetal and infant death

The aims of this study were to investigate in the human cerebellar cortex the structural and biological ontogenetic features, the possible presence of alterations in cases of sudden unexplained fetal and infant death, and the involvement of the maternal cigarette smoking in developmental abnormalities. We analyzed 52 brains of fetal and infant death victims, aged from the second gestational trimester to 12th postnatal month. In the cerebellar cortex we evaluated, besides the morphological aspects, the expression of several biomarkers implicated in proliferative processes (c-fos, proliferating cell nuclear antigen, and apoptosis) as well as the presence of the neurotransmitter somatostatin, which is strongly implicated in central nervous system differentiation, and of EN2 gene. The observed features of the cerebellar cortex, mainly confined to the transient external granular layer, were high proliferative activity and high expression of both somatostatin and EN2 gene in prenatal life and high apoptotic index after birth. In 41% of the sudden unexplained death victims, in the greater part with smoking mothers, we observed different biopathological alterations of the cerebellar cortex. Maternal smoking is increasingly being demonstrated to be one of the main contributors to developmental neurological alterations in the offspring.

Maternal smoking and sudden infant death syndrome: epidemiological study related to pathology

Various risk factors have been postulated to be related to sudden infant death syndrome (SIDS). Despite its reduction, thanks to the "Back to Sleep" campaign, SIDS is still a major cause of infant mortality in the first year of life. The purpose of this study was to correlate the different risk factors with the autopsy results and thus to determine if one or more of these variables is really specific for SIDS. We collected 128 sudden infant death victims with clinical diagnosis of SIDS and performed a complete autopsy with in-depth histology on serial sections, particularly of the brainstem, in accordance with our necropsy protocol. Histopathologic and immunohistochemical examination of the central autonomic nervous system revealed, in 78 cases of the SIDS group, the following anomalies: hypodevelopment of the arcuate nucleus, somatostatin positive hypoglossus nucleus, tyrosine hydroxylase negativity in the locus coeruleus, gliosis, and hypoplasia of the hypoglossus nucleus. A significant relation was found between maternal smoke and brainstem alterations.

Histological and biological developmental characterization of the human cerebellar cortex

The aim of this study was to investigate the histological and biological features of the human cerebellar cortex development and differentiation. We analyzed 52 brains of fetal and infant death victims, aged from 17 gestational weeks to 12th postnatal month. In particular, in the cerebellar cortex at different ages we evaluated, besides the structural aspects, the expression of several biomarkers implicated in proliferative processes (c-fos, PCNA and apoptosis). We observed morphological patterns progressively evolving every month, from the indefinite structure of the second gestational trimester to the four-layered structure (external granular layer, molecular layer, Purkinje cell layer, internal granular layer) of the late fetal cortex and subsequently to the three-layered postnatal definitive morphology, due to involution of the external granular layer. The evaluation of the biological features of the cerebellar cortex showed high proliferative activity mainly confined to the transient external granular layer in prenatal life, and high apoptotic index after birth. Thus, the histological examination, better with the support of biomarker investigations, allows with accuracy to describe the dynamic sequence of steps that occur in human cerebellar cortex development and to establish in each case the age, namely the pre- or postnatal month of life. Consequently, we can diagnose delayed or altered processes of differentiation during the development of the human cerebellar cortex.

Alterations of Biological Features of the Cerebellum in Sudden Perinatal and Infant Death

This article intends to show how the cerebellum, a structure ordinarily not considered in mediating breathing or cardiovascular control, may play a critical role in compensatory responses particularly to hypoxic insults occurring pre and/or postnatally and thus may be involved in the sudden unexplained perinatal and infant death. Besides the ontogenesis of the cerebellar cortex in man, we reported alterations of biopathological features (neuronal immaturity, altered apoptotic programs, negative expression of somatostatin and EN2 gene, intense c-fos expression positivity, astrogliosis) in the cortex and in the dentate nucleus of the 63% of sudden deaths, and only in 10% of the controls. The correlation of these results with the mother's smoking habit was highly significant. Therefore, we support the hypothesis, already expressed in previous studies on brainstem, of a close relation between maternal cigarette smoking and a wide range of morpho-physiological defects of the brain, leading to unexplained sudden death in stillbirths, newborns, and Sudden Infant Death Syndrome (SIDS) victims.

Hypoplasia and neuronal immaturity of the hypoglossal nucleus in sudden infant death

OBJECTIVE

To report the case of five month old female baby with a history of episodes of gastro-oesophageal reflux and pneumonia. Her sudden death offered a unique insight into the possible role of delayed neuronal maturation and hypoplasia of the hypoglossal nucleus in representing a likely morphological substrate of sudden death.

METHODS

Morphometric analysis was carried out with an Image-Pro Plus Image analyser (Media Cybernetics) on both sides of the brain stem.

RESULTS

Hypoplasia and neuronal immaturity of the hypoglossal nucleus were demonstrated, accompanied by hypoplasia of the arcuate nucleus.

CONCLUSIONS

Much attention should be paid to the possible role of the hypoglossal nucleus in determining a lethal outcome in infancy through impairment of deglutition and subsequent recurrent episodes of pneumonia, and as a necropsy finding.

Adverse effects of prenatal tobacco smoke exposure on biological parameters of the developing brainstem

We aimed to study the consequences of chronic exposure to tobacco smoke in utero on the morphological and functional maturation of the brainstem by comparing stillbirths of smoker mothers versus nonsmoker mothers. A total of 42 stillbirths, aged 25-40 gestational weeks, underwent autopsy according to our guidelines (). The brainstem was studied on serial sections and by immunohistochemistry to assay the expression of the EN2 gene, somatostatin (SS) and the tyrosine hydroxylase enzyme (TH). We observed a significant correlation between maternal smoking and sudden intrauterine unexplained death (SIUD), hypoplasia of the ArcN, no immunostaining of the EN2 in the arcuate nucleus (ArcN), and of TH in the locus coeruleus (LC) (P < 0.05). An increased incidence of maternal smoking was also observed in fetuses with SS negativity in the hypoglossus nucleus (HypoglN). Exposure in utero to maternal smoking may strongly interfere with brain biological parameters, giving rise not only to structural developmental abnormalities of the arcuate nucleus, but also to a decrease of noradrenergic activity in the LC, of EN2 gene expression in the ArcN and of SS in the HypoglN.

Sudden infant death syndrome (SIDS) shortly after hexavalent vaccination: another pathology in suspected SIDS?

Experts from panels of the European Agency for the Evaluation of Medical Products have investigated whether there might be a link between hexavalent vaccines and some cases of deaths that occurred. Participants included pathologists with experience in the field of vaccines and sudden infant death syndrome who conducted autopsies. However, to the best of our knowledge, little, if any, attention was paid to examination of the brainstem and the cardiac conduction systems on serial sections, nor was the possibility of a triggering role of the vaccine in these deaths considered. Herein we report the case of a 3-month-old female infant dying suddenly and unexpectedly shortly after being given a hexavalent vaccination. Examination of the brainstem on serial sections revealed bilateral hypoplasia of the arcuate nucleus. The cardiac conduction system presented persistent fetal dispersion and resorptive degeneration. This case offers a unique insight into the possible role of hexavalent vaccine in triggering a lethal outcome in a vulnerable baby. Any case of sudden unexpected death occurring perinatally and in infancy, especially soon after a vaccination, should always undergo a full necropsy study according to our guidelines.

Techniques and criteria in pathologic and forensic-medical diagnostics in sudden unexpected infant and perinatal death

For each case of sudden infant and perinatal death, a full review of clinical and epidemiologic data and a complete necropsy study were performed according to the necropsy protocol devised by the Institute of Pathology, University of Milan, Milan, Italy (available at: http://users.unimi.it/~pathol/sids_e.html). Histopathologic examination of unexpected late fetal and neonatal death and SIDS cases allowed us to identify frequent alterations, mainly congenital, of the autonomic nervous system, modulating respiratory, cardiovascular, arousal, and upper digestive activities. The data and arguments presented herein provide a brief survey tending to open, rather than conclude, a far-reaching subject and to motivate medicolegal specialists and pathologists to perform more in-depth study.

Sudden infant death syndrome "gray zone" disclosed only by a study of the brain stem on serial sections

Sudden infant death syndrome (SIDS) "gray zone" or borderline cases are defined as those cases in which it is difficult to establish whether the pathological findings are sufficiently severe to have caused the death. Examination of the brainstem in 103 cases of SIDS disclosed five SIDS "gray zone" cases in which only further investigations of serial sections successfully identified anatomico-pathological findings that likely represent the morphological substrates for a sudden reflexogenic death. A complete autopsy was performed, including close examination of the brainstem and cardiac conduction system, according to our guidelines. Our five cases are consistent with the triple-risk model of SIDS, a hypothesis postulating an underlying biological vulnerability to exogenous stressors or triggering factors in a critical developmental period. Inflammatory infiltrates (cases 1 and 2), necrotic focus of the solitary tract (case 3), hemangioendothelioma (case 4) and mild pneumonia (case 5) alone might or might not have accounted for the sudden deaths, if it had not been for the location and/or concomitant presence of brainstem abnormalities that could have had a triggering role in causing the sudden death of these babies.

Early atherosclerotic lesions in infancy: role of parental cigarette smoking

Cigarette smoking is associated with an increased incidence of atherosclerotic diseases. The aim of this study was to examine the progression of the pre atherosclerotic lesions previously observed by us in coronary arteries of fetuses of smoker mothers and in infants with smoker parents. We examined the coronary arteries of 34 infants, aged 1-36 months, and the histological and biological [c-fos, proliferating cell nuclear antigen (PCNA), and apoptosis] features of the early atherosclerotic lesions. In 17 infants (50%), at least one parent smoked, generally more than five cigarettes a day. In 18 cases (53%), we observed variable thickening of the coronary walls from pre-atherosclerotic lesions to juvenile atherosclerotic plaques, related to parental smoking habit. This morphological progression of the lesions was accompanied by a sequence of biological changes in the smooth muscle cells of the tunica media. We suggest that the oxidants present in the gas phase of the parental cigarette smoke pass through the endothelium and induce at first the c-fos gene activation and subsequently the PCNA positivity, that is, a proliferative process.

Unexpected perinatal death and sudden infant death syndrome (SIDS): anatomopathologic and legal aspects

This work intends to be a review of the recent histopathological findings elicited by research into sudden and unexpected perinatal death and sudden infant death syndrome (SIDS) that have dictated a novel approach to the inherent problems by pathologists, especially those entrusted with forensic medical authority. The new approach stems from the recent advances made in the understanding of neuro- and/or cardiac-conduction-system diseases present in unexpected perinatal death and SIDS. These demand that an accurate morphologic examination be performed of these structures, which modulate respiratory, cardiovascular, digestive, and arousal activities, in all victims of sudden death. A histopathologic study of an ample register of cases of victims of sudden death, either perinatally or in early infancy, has demonstrated frequent alterations both of the autonomic nervous system (especially hypoplasia of the arcuate nucleus) and of the cardiac conduction system (accessory atrioventricular pathways). The present research provides an in-depth study of the many still-controversial aspects underlying perinatal unexpected death and SIDS and is recommended for professionals working in the forensic field, whose greater insight into this problem will allow more complete medicolegal documentation.

Biology of the smooth muscle cells in human atherosclerosis

The aim of this study was to reconstruct dynamic biological steps of human atherosclerosis at different ages of life and, in particular, to clarify the role of the smooth muscle cells (SMCs) by means of evaluation of several markers implicated in proliferative diseases (c-fos, proliferating cell nuclear antigen: PCNA, apoptosis, chromosome 7). We examined the biological features of 67 atherosclerotic arterial lesions obtained from fetuses, infants, young people and adults. From each case serial sections were stained for histological examination, PCNA, c-fos and apoptosis detection by immunohistochemical methods and for chromosome 7 number evaluation by fluorescence in situ hybridization. In coronary specimens of fetuses we observed SMCs with c-fos positivity. In infant lesions the predominant result was positivity for PCNA. Similar results were obtained from the plaques from young subjects with a greater presence of PCNA-positive cells. In adult subjects numerous apoptotic cells were present in the stable plaques, whereas in the unstable plaques we frequently detected joint positivity for both PCNA and c-fos gene and supernumerary chromosomes 7. During the evolution of the atherosclerotic process we observed a biological modulation of SMC proliferation, which begins after activation of the c-fos gene, increases during progression of the lesion and declines in stable plaques, when apoptosis increases. In unstable plaques, the same early steps observed in fetus and infant arteries occur. The observation in some cases of chromosome 7 alterations, markers of tumorigenesis, suggests the possible transformation of an advanced atherosclerotic plaque into a neoplastic-like process.

Involvement of the EN-2 gene in normal and abnormal development of the human arcuate nucleus

In this study, we wanted to evaluate whether the engrailed EN-2 gene, a homeobox gene with an essential role in the development of the rhombic lip derivatives in different species, is (1) expressed also in man in the differentiation process of the medullary arcuate nucleus (ArcN) and (2) involved in sudden unexplained perinatal and infant death, frequently related to developmental defects of the ArcN. We evaluated by means of the monoclonal antibody 4D9, exclusively recognizing engrailed-2 protein, the expression of the EN-2 gene in the ArcN on histological sections of the brainstems of 30 subjects aged from 17 gestational weeks to 10 postnatal months, who had died of known (17 cases) and unknown causes (13 cases). We observed in the greater number of the cases that the expression of the EN-2 gene is very high in the ArcN neurons from the 17th to the 22nd gestational week, then decreases up to the first days after birth and later disappears. Moreover, in eight of the 13 sudden deaths (61%), a hypoplasia of the ArcN was present. In almost all of these cases, EN-2 expression was negative. In conclusion, we support the role of the EN-2 gene in the normal neuronal development and in the anatomic organization of the human ArcN as well as the possible existence of EN-2 mutations related to hypoplasia of this nucleus.

Sudden infant death triggered by dive reflex

The dive reflex is the reflex mechanism most frequently considered in the aetiopathogenesis of sudden infant death syndrome (SIDS). This seems to persist in human beings as an inheritance from diver birds and amphibians. It has been reported that washing the face with cold water or plunging into cold water can provoke cardiac deceleration through the intervention of the ambiguus and the vagal dorsal nuclei. This report describes a case of SIDS that offers a unique insight into the role of the dive reflex in determining a lethal outcome. Examination of the brainstem on serial sections revealed severe bilateral hypoplasia of the arcuate nucleus and gliosis of the other cardiorespiratory medullary nuclei. The coronary and cardiac conduction arteries presented early atherosclerotic lesions. The possible role of parental cigarette smoking in the pathogenesis of arcuate nucleus hypoplasia and early coronary atherosclerotic lesions is also discussed.