CMV-DNA detection in parenchymatous organs in cases of SIDS

Clinical and experimental aspects of breathing modulation by inflammation

Neuroinflammation is produced by local or systemic alterations and mediated mainly by glia, affecting the activity of various neural circuits including those involved in breathing rhythm generation and control. Several pathological conditions, such as sudden infant death syndrome, obstructive sleep apnea and asthma exert an inflammatory influence on breathing-related circuits. Consequently breathing (both resting and ventilatory responses to physiological challenges), is affected; e.g., responses to hypoxia and hypercapnia are compromised. Moreover, inflammation can induce long-lasting changes in breathing and affect adaptive plasticity; e.g., hypoxic acclimatization or long-term facilitation. Mediators of the influences of inflammation on breathing are most likely proinflammatory molecules such as cytokines and prostaglandins. The focus of this review is to summarize the available information concerning the modulation of the breathing function by inflammation and the cellular and molecular aspects of this process. I will consider: 1) some clinical and experimental conditions in which inflammation influences breathing; 2) the variety of experimental approaches used to understand this inflammatory modulation; 3) the likely cellular and molecular mechanisms.

Back to the Future - Part 1. The medico-legal autopsy from ancient civilization to the post-genomic era

Part 1 of the review "Back to the Future" examines the historical evolution of the medico-legal autopsy and microscopy techniques, from Ancient Civilization to the Post-Genomic Era. In the section focusing on "The Past", the study of historical sources concerning the origins and development of the medico-legal autopsy, from the Bronze Age until the Middle Ages, shows how, as early as 2000 BC, the performance of autopsies for medico-legal purposes was a known and widespread practice in some ancient civilizations in Egypt, the Far East and later in Europe. In the section focusing on "The Present", the improvement of autopsy techniques by Friedrich Albert Zenker and Rudolf Virchow and the contemporary development of optical microscopy techniques for forensic purposes during the 19th and 20th centuries are reported, emphasizing, the regulation of medico-legal autopsies in diverse nations around the world and the publication of international guidelines or best practices elaborated by International Scientific Societies. Finally, in "The Future" section, innovative robotized and advanced microscopy systems and techniques, including their possible use in the bio-medicolegal field, are reported, which should lead to the improvement and standardization of the autopsy methodology, thereby achieving a more precise identification of natural and traumatic pathologies.

Post-mortem diagnosis, of cytomegalovirus and varicella zoster virus co-infection by combined histology and tissue molecular biology, in a sudden unexplained infant death

BACKGROUND

An autopsy case of a two-month-old male infant who suddenly and unexpectedly died during his sleep, eight days after the onset of benign varicella.

OBJECTIVES

To describe post-mortem combined histological and tissue molecular biological techniques for the diagnosis of cytomegalovirus and varicella zoster virus co-infection as a cause of death.

STUDY DESIGN

Real-time quantitative PCR and RT-PCR assays for Herpesviruses, respiratory viruses, Adenovirus, Enterovirus and Parvovirus B19 were performed on multi-organ frozen samples and paraffin-embedded tissues in combination with histology.

RESULTS

Cytomegalovirus and varicella zoster virus were detected by molecular biology with highest viral loads detected in the lungs (4.6×10(7) and 1.9×10(5) genome copies per million of cells, respectively). Pulmonary extensive necrotizing inflammation and immunohistochemistry correlated to virological data. Virological molecular biology was negative on paraffin-embedded tissues.

CONCLUSIONS

This case shows that thorough quantitative virological investigations on frozen tissues must be performed in combination with histology and immunohistochemistry for the determination of the cause of a sudden unexplained infant death.

Cytomegalovirus-induced pneumonia and myocarditis in three cases of suspected sudden infant death syndrome (SIDS): Diagnosis by immunohistochemical techniques and molecularpathologic methods

Immunohistochemical and molecularpathologic techniques have improved the diagnosis of myocarditis as compared with conventional histologic staining methods done according to the Dallas criteria. Additionally, immunohistochemistry and in situ-hybridization are able to demonstrate viral infection, e.g. cytomegaloviruses in salivary glands and lungs, locations both known to be involved in cytomegalovirusinfection. However, in many cases of proved cytomegalovirusinfection the cause of death remains unclear. We report on three children younger than 1-year of age, who died suddenly without prodromal symptoms. Their deaths were attributed to SIDS (sudden infant death syndrome). In situ-hybridization, immunohistochemical (LCA, CD45R0, CD68, MHC-class-II-molecules, E-selectine) and molecularpathologic investigations (PCR), however, suggested that death was caused by a cytomegalovirus-induced pneumonia or myocarditis. In the future, these methods should be used for investigating cases with suspicion of SIDS.

Possible pathomechanisms of sudden infant death syndrome: key role of chronic hypoxia, infection/inflammation states, cytokine irregularities, and metabolic trauma in genetically predisposed infants

Chronic hypoxia, viral infections/bacterial toxins, inflammation states, biochemical disorders, and genetic abnormalities are the most likely trigger of sudden infant death syndrome (SIDS). Autopsy studies have shown increased pulmonary density of macrophages and markedly more eosinophils in the lungs accompanied by increased T and B lymphocytes. The elevated levels of immunoglobulins, about 20% more muscle in the pulmonary arteries, increased airway smooth muscle cells, and increased fetal hemoglobin and erythropoietin are evidence of chronic hypoxia before death. Other abnormal findings included mucosal immune stimulation of the tracheal wall, duodenal mucosa, and palatine tonsils, and circulating interferon. Low normal or higher blood levels of cortisol often with petechiae on intrathoracic organs, depleted maternal IgG antibodies to endotoxin core (EndoCAb) and early IgM EndoCAb triggered, partial deletions of the C4 gene, and frequent IL-10-592*A polymorphism in SIDS victims as well as possible hypoxia-induced decreased production of antiinflammatory, antiimmune, and antifibrotic cytokine IL-10, may be responsible for the excessive reactions to otherwise harmless infections. In SIDS infants, during chronic hypoxia and times of infection/inflammation, several proinflammatory cytokines are released in large quantities, sometimes also representing a potential source of tissue damage if their production is not sufficiently well controlled, eg, by pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP). These proinflammatory cytokines down-regulate gene expression of major cytochrome P-450 and/or other enzymes with the specific effects on mRNA levels, protein expression, and enzyme activity, thus affecting metabolism of several endogenous lipophilic substances, such as steroids, lipid-soluble vitamins, prostaglandins, leukotrienes, thromboxanes, and exogenous substances. In SIDS victims, chronic hypoxia, TNF-alpha and other inflammatory cytokines, and arachidonic acid (AA) as well as n-3 polyunsaturated fatty acids (FA), stimulated and/or augmented superoxide generation by polymorphonuclear leukocytes, which contributed to tissue damage. Chronic hypoxia, increased amounts of nonheme iron in the liver and adrenals of these infants, enhanced activity of CYP2C9 regarded as the functional source of reactive oxygen species (ROS) in some endothelial cells, and nicotine accumulation in tissues also intensified production of ROS. These increased quantities of proinflammatory cytokines, ROS, AA, and nitric oxide (NO) also resulted in suppression of many CYP450 and other enzymes, eg, phosphoenolpyruvate carboxykinase (PEPCK), an enzyme important in the metabolism of FA during gluconeogenesis and glyceroneogenesis. PEPCK deficit found in SIDS infants (caused also by vitamin A deficiency) and eventually enhanced by PACAP lipolysis of adipocyte triglycerides resulted in an increased FA level in blood because of their impaired reesterification to triacylglycerol in adipocytes. In turn, the overproduction and release of FA into the blood of SIDS victims could lead to the metabolic syndrome and an early phase of type 2 diabetes. This is probably the reason for the secondary overexpression of the hepatic CYP2C8/9 content and activity reported in SIDS infants, which intensified AA metabolism. Pulmonary edema and petechial hemorrhages often present in SIDS victims may be the result of the vascular leak syndrome caused by IL-2 and IFN-alpha. Chronic hypoxia with the release of proinflammatory mediators IL-1alpha, IL-1beta and IL-6, and overloading of the cardiovascular and respiratory systems due to the narrowing airways and small pulmonary arteries of these children could also contribute to the development of these abnormalities. Moreover, chronic hypoxia of SIDS infants induced also production of hypoxia-inducible factor 1alpha (HIF-1alpha), which stimulated synthesis and release of different growth factors by vascular endothelial cells and intensified subclinical inflammatory reactions in the central nervous system, perhaps potentiated also by PACAP and VIP gene mutations. These processes could lead to the development of brainstem gliosis and disorders in the release of neuromediators important for physiologic sleep regulation. All these changes as well as eventual PACAP abnormalities could result in disturbed homeostatic control of the cardiovascular and respiratory responses of SIDS victims, which, combined with the nicotine effects and metabolic trauma, finally lead to death in these often genetically predisposed children.

Detection of RNA viruses in sudden infant death (SID)

Continuing previous work, reverse transcriptase polymerase chain reaction approaches for the detection of RNA viruses (influenza A+B, parainfluenza virus 3, respiratory syncytial virus) were developed. A total of 118 infant deaths, including 13 cases of non-natural death (nND), 78 cases of natural death (ND) without morphological signs of interstitial pneumonia (IP), 27 cases showing IP (ND+IP), were investigated using frozen lung tissue ( N=100) and paraffin-embedded material ( N=18). In five of the autopsy cases (ND+IP) the influenza B virus genome could be detected and the other types of viruses were completely negative. Together with previous results (detection of adenoviruses and cytomegaloviruses) in the same groups, the frequency of virus detection in the cases with IP was 48% compared with 14% in the ND without IP and 7% in the nND. Significant differences in the frequency of virus detection were also obtained when the cases were divided in SIDS and non-SIDS. The results obtained indicate an association between IP and some viruses and support the hypothesis that respiratory virus infections could act as trigger in sudden infant death.

A comparison of respiratory symptoms and inflammation in sudden infant death syndrome and in accidental or inflicted infant death

Upper respiratory infection and pulmonary inflammation are common in sudden infant death syndrome, but their role in the cause of death remains controversial. Controlled studies comparing clinical upper respiratory infection and inflammation in sudden infant death syndrome with sudden infant deaths caused by accidents and inflicted injuries (controls) are unavailable. Our aim was to compare respiratory inflammation and upper respiratory infection within 48 hours of death and postmortem culture results in these two groups. A retrospective analysis of upper respiratory infection and pathologic variables in the trachea and lung of 155 infants dying of sudden infant death syndrome and 33 control infants was undertaken. Upper respiratory infection was present in 39% of sudden infant death syndrome cases and 40% of control cases. Upper respiratory infection was more likely to have occurred in association with more severe lymphocytic interstitial pneumonitis when sudden infant death syndrome cases and control cases were combined ( P=.04). Proximal and distal tracheal lymphocytic infiltration was more severe in control cases than in sudden infant death syndrome cases ( P=.01 and.01, respectively). Lymphocytic infiltrations of the bronchi, bronchioles, and pulmonary interstitium were similar between groups. Bronchial associated lymphoid tissue was more prominent in control cases ( P=.04). Cultures were positive in 80% of sudden infant death syndrome cases, 78% of which were polymicrobial. Among control cases, 89% were positive, with 94% being polymicrobial. This study confirms that microscopic inflammatory infiltrates in sudden infant death syndrome are not lethal.

Molecular biology in cerebral cortex of sudden infant death syndrome

Full-scale investigations of sudden infant death syndrome (SIDS) by methods of molecular pathology have been carried out. This paper reports the basic preliminary data of SIDS cerebral cortex analyzed by restriction landmark genomic scanning (RLGS) method, which is the second dimension electrophoresis of DNA recently developed in Japan. The RLGS method was carried out separately using the cerebral cortex of a 4-month-old infant with SIDS and using the cerebral cortex of a 3-month-old infant as a control to investigate SIDS-specific spots. As a result, the coincidence rate of spots between the infant with SIDS and the infant without SIDS was 98.12%. The average coincidence rate of spots in humans is usually 99.07%. Therefore, it was confirmed that the coincidence rate of spots by RLGS between the infant with SIDS and the infant without SIDS was lower than that in humans. In addition, the incidence of SIDS-specific spots was 1.19% and the incidence of non-SIDS-specific spots was 0.6%.

Review of risk factors for sudden infant death syndrome

Sudden infant death syndrome (SIDS) accounts for the largest number of deaths during the first year of life in developed countries. The possible causes of SIDS are numerous and, to date, there is no adequate unifying pathological explanation for SIDS. Epidemiological studies have played a key role in identifying risk factors, knowledge of which has underpinned successful preventive programmes. This review critically assesses information on the main risk factors and causal hypotheses put forward for SIDS, focusing on research published since 1994. The overall picture that emerges from this review is that affected infants are not completely normal in development, but possess some inherent weakness, which may only become obvious when the infant is subjected to stress. Initially there may be some minor impairment or delay in development of respiratory, cardiovascular or neuromuscular function. None of these is likely to be sufficient, in isolation, to cause death and, provided the infant survives the first year of life, may no longer be of any significance. However, when a compromised infant is confronted with one or more stressful situations, several of which are now clearly identified as risk factors, and from which the majority of infants would normally escape, the combination may prove fatal.

Increase of pulmonary density of macrophages in sudden infant death syndrome

A 1996 cytodensitometric study found increased cellular density in the pulmonary parenchyma of infants who died of sudden infant death syndrome (SIDS). The present study clarifies these results in quantifying the density of immunohistochemical subtyped inflammatory cells. Histomorphometry was used to compare the density of macrophages, granulocytes and T and B lymphocytes in the lungs of two groups of infants. From the post-mortem records of infant deaths between 1983 and 1995, 29 (mean age = 5 months) were randomly selected including 16 cases of SIDS and 13 who died of other non-pulmonary causes. Densities of immunoreactive cells were measured under blind conditions in the parenchyma. The mean density of macrophages was significantly higher in cases of SIDS compared with the controls (P = 0.0318), but there were no differences for the lymphocytes and the granulocytes. These morphometrical results must be interpreted within the methodological limits of this study, especially the non-uniform level of lung inflation between selected subjects. However, the differences in level of inflation are not sufficient to explain the observed increase of macrophage density. Indeed, the mean values of alveolar surface area, which represent an indirect measure of lung inflation, are not significantly different between the two groups. Increase of pulmonary macrophage density in SIDS agrees with three non-exclusive hypotheses: (1) an abnormal inflammatory reaction by expression of Th1 helper cell phenotype activation; (2) consequence of passive smoking; and (3) post-agonal mechanisms. Bacterial superantigens produced by toxigenic bacteria in the respiratory tract could play a role as a trigger factor that initiates a fatal cascade with overproduction of cytokines leading to death. The significant increase of pulmonary macrophage density would be the morphological expression of this potential mechanism of death.

Differential diagnosis of postoperative liver failure in a 12-year-old child

The case of a 12-year-old child who died of fulminant hepatic failure a few days after tonsillectomy is reported. Histological examination revealed large areas of massive centrilobular hepatic necrosis. Hepatotoxicity of postoperatively administered paracetamol in high dosages combined with enflurane exposure is discussed as a cause for the hepatic failure. The fulminant clinical course could have been influenced by an infection with hepatitis G virus which was detected in liver tissue by in situ hybridisation and was probably transmitted via transfusion of blood plasma.