Capsule-supporting ring: a new device for resin embedding of glass-mounted specimens.

The goal of specimen preparation for transmission electron microscopy is to obtain high-quality ultra-thin sections with which we can correlate cellular structure to physiological function. In this study, we newly developed a capsule-supporting ring that can be useful for resin embedding of glass-mounted specimens. The present device allowed us to re-embed a semi-thin section on a microscope slide into a resin block not only for efficient ultra-thin sectioning but also for a correlative light and electron microscopy. Similar to epoxy resins for morphological observations, semi-thin sections of low-viscosity hydrophilic resins, such as Lowicryl series, can be re-embedded into the resin, which can be useful for cytochemical gold labelling. A further application of the present device improved flat embedding of cultured cells on glass cover slips for electron microscopy, preserving in situ sub-cellular structures close to their native state. We practically describe the use of capsule-supporting ring and demonstrate representative micrographs as results.

Calreticulin mutant mice develop essential thrombocythemia that is ameliorated by the JAK inhibitor ruxolitinib.

Mutations of calreticulin (CALR) are detected in 25-30% of patients with essential thrombocythemia (ET) or primary myelofibrosis and cause frameshifts that result in proteins with a novel C-terminal. We demonstrate that CALR mutations activated signal transducer and activator of transcription 5 (STAT5) in 293T cells in the presence of thrombopoietin receptor (MPL). Human megakaryocytic CMK11-5 cells and erythroleukemic F-36P-MPL cells with knocked-in CALR mutations showed increased growth and acquisition of cytokine-independent growth, respectively, accompanied by STAT5 phosphorylation. Transgenic mice expressing a human CALR mutation with a 52 bp deletion (CALRdel52-transgenic mice (TG)) developed ET, with an increase in platelet count, but not hemoglobin level or white blood cell count, in association with an increase in bone marrow (BM) mature megakaryocytes. CALRdel52 BM cells did not drive away wild-type (WT) BM cells in in vivo competitive serial transplantation assays, suggesting that the self-renewal capacity of CALRdel52 hematopoietic stem cells (HSCs) was comparable to that of WT HSCs. Therapy with the Janus kinase (JAK) inhibitor ruxolitinib ameliorated the thrombocytosis in TG mice and attenuated the increase in number of BM megakaryocytes and HSCs. Taken together, our study provides a model showing that the C-terminal of mutant CALR activated JAK-STAT signaling specifically downstream of MPL and may have a central role in CALR-induced myeloproliferative neoplasms.

Apnea, glial apoptosis and neuronal plasticity in the arousal pathway of victims of SIDS.

Of 27,000 infants whose sleep-wake characteristics were studied under the age of 6 months, 38 died unexpectedly 2-12 weeks after the sleep recording in a pediatric sleep laboratory. Of these infants, 26 died of sudden infant death syndrome (SIDS), and 12 of definitely identified causes. The frequency and duration of sleep apneas were analysed. Sleep recordings and brainstem histopathology were studied to elucidate the possible relationship between sleep apnea and neuropathological changes within the arousal system. Immunohistochemical analyses were conducted using tryptophan hydroxylase (TrypH), a serotonin synthesizing enzyme, and growth-associated phosphoprotein 43 (GAP43), a marker of synaptic plasticity. The terminal-deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method was used for apoptosis. The pathological and physiological data were correlated for each infant. In the SIDS victims, statistically significant positive correlations were seen between the number of TrypH-positive neurons in the dorsal raphe nucleus of the midbrain and the duration of central apneas (p = 0.03), between the number of TUNEL-positive glial cells in the pedunculopontine tegmental nucleus (PPTN) and the average number of spines in GAP43-positive neurons in the PPTN (p = 0.04). These findings in the dorsal raphe nucleus of the midbrain and PPTN, that play important roles in the arousal pathway suggest a possible link between changes in arousal and SIDS.

CALNUC (nucleobindin) is localized in the Golgi apparatus in insect cells.

A mouse monoclonal antibody 12B1 was raised against Golgi fractions from Sf21 insect cells and selected as Golgi-specific by immunostaining of the cells. The antigen was purified from the cells by immunoaffinity chromatography with the monoclonal antibody, and its N-terminal and internal amino acid sequences were determined. Based on the partial amino acid sequences, cDNA encoding the antigen protein was cloned and sequenced. The amino acid sequence deduced from the cDNA nucleotide sequence showed a homology to those of CALNUC family proteins, CALNUC (or nucleobindin, a calcium-binding Golgi protein with DNA-binding activity) and protein NEFA (a cell surface protein with DNA-binding, EF-hand, and acidic domains). The insect protein had two EF-hand loops at the same sites as the mammalian CALNUC family proteins, but had no leucine zipper which the mammalian homologues commonly have. An electron microscopic immunoperoxidase study demonstrated that the insect protein was localized in the cis-Golgi cisternae and cis-Golgi networks. Since this localization is identical to that of mammalian CALNUC, the insect protein was considered to be a homologue of CALNUC rather than that of NEFA. Assays involving proteinase K digestion, sodium carbonate extraction and Triton X-114 extraction revealed that the insect CALNUC-like protein was a soluble protein tightly associated with the luminal surface of Golgi membranes as reported for mammalian CALNUC. The insect protein was also shown to have calcium-binding activity as does mammalian CALNUC. These data verify that the insect protein is CALNUC. The existence of CALNUC in insect cells suggests that CALNUC is an essential calcium-binding Golgi protein in a wide range of the animal kingdom. A phylogenetic tree analysis, however, suggested that NEFA was derived from CALNUC long after the segregation of a mammalian ancestor from an insect ancestor.

Ghrelin, a novel growth hormone-releasing acylated peptide, is synthesized in a distinct endocrine cell type in the gastrointestinal tracts of rats and humans.

Ghrelin, a novel GH-releasing acylated peptide, was recently isolated from rat stomach. It stimulated the release of GH from the anterior pituitary through the GH secretagogue receptor (GHS-R). Ghrelin messenger RNA and the peptide are present in rat stomach, but its cellular source has yet to be determined. Using two different antibodies against the N- and C-terminal regions of rat ghrelin, we identified ghrelin-producing cells in the gastrointestinal tracts of rats and humans by light and electron microscopic immunohistochemistry and in situ hybridization combined with immunohistochemistry. Ghrelin-immunoreactive cells, which are not enterochromaffin-like cells, D cells, or enterochromaffin cells, accounted for about 20% of the endocrine cell population in rat and human oxyntic glands. Rat ghrelin was present in round, compact, electron-dense granules compatible with those of X/A-like cells whose hormonal product and physiological functions have not previously been clarified. The localization, population, and ultrastructural features of ghrelin-producing cells (Gr cells) indicate that they are X/A-like cells. Ghrelin also was found in enteric endocrine cells of rats and humans. Using two RIAs for the N- and C-terminal regions of ghrelin, we determined its content in the rat gastrointestinal tract. Rat ghrelin was present from the stomach to the colon, with the highest content being in the gastric fundus. Messenger RNAs of ghrelin and GHS-R also were found in these organs. Ghrelin probably functions not only in the control of GH secretion, but also in the regulation of diverse processes of the digestive system. Our findings provide clues to additional, as yet undefined, physiological functions of this novel gastrointestinal hormone.

Multistratified expression of polysialic acid and its relationship to VAChT-containing neurons in the inner plexiform layer of adult rat retina.

We investigated the localization of polysialic acid (PSA), neural cell adhesion molecule (NCAM), and vesicular acetylcholine transporter (VAChT) in adult rat retina by using immunofluorescence with a confocal laser scanning microscope. Western blot analysis showed a typical broad smear of PSA and isoforms of NCAM (120, 140, and 180 kD). PSA immunofluorescence revealed multistratification in the inner plexiform layer (IPL). Dual immunostaining for PSA and NCAM exhibited the selective co-expression of PSA and NCAM on Müller cells. Moreover, dual immunolabeling for PSA and VAChT completely separated the five strata in the IPL. Strata 1, 3, and 5 were immunoreactive for PSA and Strata 2 and 4 for VAChT. These results suggest the possibility that PSA molecules on Müller cells are spatially related to ON and OFF retinal channels in the IPL.

Japanese national SIDS project: 1998-2000 research for the improvement of infant mortality.

The aim of the present study is to see if by conducting research on sudden infant death syndrome (SIDS), one of major contributing factors to infant mortality in Japan, infant mortality can be reduced. Concrete approaches taken in this study took four different directions: elucidation of SIDS etiology, prevention, elucidation of its social aspects (education) and the investigation of administrative aspects. At the same time, an attempt was made to get better grasp on the epidemiological trends in infant mortality, including that of SIDS. The idea behind this etiological approach was to unify hitherto separate approaches taken by those in epidemiological, physiological and pathological fields. A molecular-biological approach was also added. Physiologically hypothesized causes of SIDS--apnea and arousal disorder--together with the epidemiologically presumed risk factor of sleeping position, were examined jointly from a pathological viewpoint. Research in the first 2 years of the grant found that hypoxia reflected by gliosis in the brain stem arousal pathway was related to the duration of sleep apnea. Research in the final year of the grant found the possibility of organic fragility in the brain stem arousal pathway, particularly in periaqueducal gray matter and pedunculopontine nucleus reflected by apoptosis and neuronal plasticity. These findings gave support to the arousal disorder hypothesis in SIDS. Application of the restriction landmark genomic scanning (RLGS) method supported the possibility of locating a site for a SIDS-specific gene. The US collaborative home infant monitoring evaluation (CHIME) currently in use was evaluated. In addition, three new monitoring methods were developed: a non-invasive multi-channel pressure-sensing bed, microwave radar, and a pacifier that functions as a suckometer which can be used to evaluate a neonate's autonomic nervous functions. Social (educational) activities included: surveys of the current state of educational campaigns on SIDS in other countries, epidemiological evaluation of campaigns run by the Japan SIDS families' Association to evaluate the effectiveness of the SIDS campaign, and creation of a home page, mostly to inform the public about the output from this research group. "Guidelines for Death Scene Investigation of Sudden, Unexplained Infant Deaths: Recommendations of Interagency Panel on Sudden Infant Death Syndrome" was translated into japanese. Activities that concerned administrative measures included clarification of the unique nature of SIDS-related trials in Japan when compared to those in the United States. Other concrete administrative proposals were: a pressing need to increase the rate of SIDS-related autopsies to facilitate a better etiological understanding and, for this purpose, establishing regulations in local jurisdictions and amending Article 8 of the Postmortem Examination and Corpse Preservation Act, keeping in perspective the medico-economic evaluation of the japanese medical examiner system. For these proposals to be realized, establishment of a new office in charge of administrative and approved autopsies at the national level of government is desirable. Also pointed out were the different opinions held among specialists concerning the diagnosis of SIDS and their need to hold multiple conferences to unify their views. Basic data for these conferences were provided from epidemiological examinations of infant mortality.

Comparative evaluation of diagnostic guidelines for sudden infant death syndrome (SIDS) in Japan.

It is a well-recognized fact among professionals that the diagnosis of sudden infant death syndrome (SIDS) involves difficult elements; a SIDS diagnosis is not uniform throughout Japan; and such a diagnosis is not made based on any internationally recognized definition. Faced with this situation, guidelines have been prepared and proposals have been made to standardize and improve the accuracy of SIDS diagnoses, viz. the following three can be cited: "guideline for diagnosis of SIDS" prepared by a Study Group of the Ministry of Health and Welfare; "case studies of SIDS" and a "guideline for its diagnosis" prepared by the Case Study Committee of Japan SIDS Research Society; and a "proposal on the principles of medico-legal pathology concerning SIDS", included in the research report supported by a Grant-in-Aid for Scientific Research from the Ministry of Education. In the current study, a comparison was made focusing on the discrepancies among these three documents. The major discrepancies among these three are: (1) handling of the patient's age (by months or years) in the diagnosis of SIDS; (2) dealing with those cases for which no autopsy has been conducted; (3) attitudes concerning whether sleeping in a prone posture is a cause for asphyxia and (4) opinions concerning the aspiration of vomited milk. It is anticipated that these discrepancies will invite confusion and affect judgments and recognition of SIDS-related cases that will be brought to court. It is essential that those involved with these three documents have an opportunity at the earliest time to discuss the matter and come to a uniform understanding.

Changes in DNA induced by toxic agents.

This is a preliminary report on significant alterations in the DNA profile caused by toxic substances which potentially has profound implications for the use of DNA techniques in identification. Acute DNA changes in the globus pallidus of the brain in man caused by carbon monoxide poisoning were detected by DNA profiling with probe 33.15. Chronic DNA changes in rabbits caused by methamphetamine were detected by DNA profiling with probe 33.15, AmpFLP on D1S80, TH01, CSF1PO and TPOX loci. Pre-intoxication bands appeared, disappeared or were discoloured after intoxication. With PCR-dot blot hybridization testing for HLADQ alpha, pre-intoxication positive spots became negative after intoxication and pre-intoxication negative spots became positive after intoxication. Intravenous injection of 10 mg/kg of methamphetamine every 2 days for 2 weeks was a large enough dose for inducement of genetic changes. In this investigation, clear changes in DNA due to intoxication were confirmed.

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%.

The epidemiological study on registered cases of sudden infant death syndrome (SIDS) in Tokyo: examination of the effect of autopsy on diagnosis of SIDS and the mortality statistics in Japan.

In the United States and most of European countries, a diagnosis of sudden infant death syndrome (SIDS) may be given only after an autopsy has been performed. Under the new definition of SIDS in Japan, an autopsy is now mandatory for the diagnosis of SIDS. However, according to the official records on autopsies, the proportion of autopsy for sudden infant death in Japan is still low (less than 30%). If a physician suspects SIDS from a review of the patient's medical history and medical findings, he can write 'suspected SIDS' as the cause of death on the death certificate without performing an autopsy. Such a clinical diagnosis is entered in the Vital Statistics section by the Japanese Ministry of Health and Welfare. In this report, a comparative epidemiological survey of registered cases of SIDS--after autopsy and with no autopsy--was carried out by examining the data from the death certificates registered by the Japanese Ministry of Health and Welfare (vital statistics in Tokyo from January 1979 to December 1996). There were 369 cases of SIDS registered in Tokyo. We found 247 diagnosed after autopsy (66.9%) and 122 with no autopsy (33.1%). The following epidemiological variables were used: address of the deceased (a specific area in Tokyo), sex, year of death, time of death, month of death, age at death, occupation of householders, and place of death. There were epidemiological differences at the 0.05 significance level between registered cases diagnosed after autopsy and those diagnosed without autopsies, as follows: year (P=0.016) and place of death (P=0.037). In addition, there were slight epidemiological differences at the 0.10 significance level between registered cases diagnosed after autopsy and with no autopsy, as follows: month of death (P=0.076) and age at death (P=0.082). This suggests that the quality of diagnosis of SIDS is not completely guaranteed. With respect to the area of residence, the incidence of SIDS is high in those areas where autopsy is performed frequently. In Tokyo, the medical examiner system is enforced only in the urban area and there is a possibility that SIDS is being underdiagnosed in the rural area of the Metropolitan Tokyo. It is likely that the diagnosis of SIDS without autopsy will influence the quality of SIDS diagnoses. The administrative inadequacy in the autopsy system in Japan should be corrected to improve the accuracy of SIDS diagnosis.

Comparison between SIDS-related court cases in the United States and Japan--a trend seen in legal precedents in the United States.

A bibliographic search of "Lexis", a database on foreign legal cases, was conducted, using sudden infant death syndrome (SIDS) as a key word to retrieve legal cases related to SIDS in the United States. The procedure yielded 156 cases, which included many that were brought to the courts for reasons other than SIDS. The following explanation was given for this outcome: because the public in the United States is much better informed about SIDS than in Japan, few cases are brought to the courts with SIDS as the main cause of the argument; the acronym, SIDS, is simply quoted during the court proceedings. Nevertheless, 26 cases that were particularly related to SIDS were selected and compared against 33 cases recorded and retrieved in the previous year in Japan to find the difference in the trends in legal disputes. The difference in the trends in litigation in the two countries was evident: in most cases in Japan, the legal dispute was over the recognition of SIDS or asphyxiation as the cause of death that had occurred in a nursery or hospital, with the family acting as the plaintiff and the nursery or hospital as the defendant. In the majority of cases in the United States, on the other hand, the state was the plaintiff and the family or baby sitter the defendant; the focal point of the dispute was the distinction between SIDS and child abuse. Compared with the trend in Japan, a much greater number of cases were brought before the court of final appeals in the United States. As the public becomes more aware of SIDS through campaigns and other means, the pattern seen in the legal disputes refer to SIDS lawsuits in Japan may change into that seen in the United States.

Research for improving the autopsy rate for infant death--medical economic assessment of the forensic autopsy system in Japan.

The rate at which autopsies are performed in Japan for cases of infant death is not adequate for diagnosing sudden infant death syndrome (SIDS). In Japan, it will be necessary to increase the autopsy rate at the time of infant deaths in order to improve the certainty of diagnosing SIDS and improving the accuracy of determining the cause of death with respect to infant death. The objective of this research is to provide basic documentation required for administrative implementation of this objective. In Japan, the Medical Examiner System and its related Approved Autopsy System are not deployed nationwide. The estimated budget in the case of deploying the Medical Examiner System nationwide for the purpose of improving the infant death autopsy rate is in excess of 5 trillion yen, and that in the case of deploying the Approved Autopsy System nationwide is estimated at roughly 130 million US dollars. However, since the rate of autopsies performed for SIDS has not changed following the implementation of approved autopsies, the efficacy of the Approved Autopsy System has come to be viewed questionably. In addition, it is also necessary to enact legislation that mandates the conducting of autopsies for all cases of infant death as is done in Scandinavia. The required cost in the case of performing autopsies for all cases of abnormal infant death is estimated at 200,000-700,000 US dollars and is considered to be within a range that could be implemented through local government regulations. In addition, the cost per body of an autopsy performed at the State Crime Laboratory in the State of Arkansas in the US in 1999 was about 6000 US dollars. In contrast, the same cost at the Tokyo Medical Examiner Office is much less at only about 4000 US dollars.

Comparative analysis of differences by gender in sudden infant death syndrome in Hungary and Japan.

We examined the sex ratio in sudden infant death syndrome (SIDS) cases in Hungary, in Tokyo and Japan between 1985 and 1996. From all the infant death cases in Hungary 395 (240 male, 155 female) were SIDS (odds ratio (OR)=1.179, with 95% confidence interval (CI)=0.961, 1.446), in Japan 4348 (2550 male, 1798 female) were SIDS (OR=1.145, with 95% CI=1.076, 1.218) and in Tokyo 307 (178 male, 129 female) were SIDS (OR=1.128, with 95% CI=0.894, 1.423). Male infants showed a significantly higher birth rate than females. The male infants are more vulnerable (p<0.005), however, higher mortality among male infants should not be considered a characteristic feature for SIDS.

Sudden infant deaths: from epidemiology to physiology.

The incidence of sudden infant death syndrome (SIDS) has dropped significantly in most countries following the development of education campaigns on the avoidance of risk factors for SIDS. However, questions have been raised about the physiological mechanism responsible for the effects of these environmental risk factors. Since 1985, a series of prospective, multicentric studies have been developed to address these questions; over 20,000 infants were recorded during one night in a sleep laboratory and among these, 40 infants eventually died of SIDS. In this review, the following methods were employed: sleep recordings and analysis, monitoring procedure, data analysis of sleep stages, cardiorespiratory and oxygen saturation, scoring of arousals, spectral analysis of the heart rate and the determination of arousal thresholds, and statistical analysis and the results including sleep apneas, arousals and heart rate and autonomic controls in both future SIDS victims and normal infants were introduced separately. In addition, the physiological effect of prenatal risk factors (maternal smoking during gestation) and postnatal risk factors (administration of sedative drugs, prone sleeping position, ambient temperature, sleeping with the face covered by a bed sheet, pacifiers and breastfeeding) in normal infants were analyzed. In conclusion, the physiological studies undertaken on the basis of epidemiological findings provide some clues about the physiological mechanisms linked with SIDS. Although the description of the mechanisms responsible for SIDS is still far from complete, it appears to involve both arousal responses and cardiac autonomic controls during sleep-wake processes.

Analysis of SIDS-related civil and criminal court cases in Japan.

Thirty-three sudden infant death syndrome (SIDS)-related civil and criminal lawsuits in Japan were retrieved from judicial precedent databases "Hanrei Masutar (Judicial Decisions Master)" and "Hanrei Taikei (Judicial Decisions System) using "SIDS" as a keyword. Sleeping posture and developmental stage of occurrence were studied in each of the cases retrieved, whether or not a legal autopsy had been performed. The influence exerted on court decisions by Japanese definitions of SIDS as well as the relationship between causes of death and court decisions were studied. Of 33, two were criminal cases (business/professional negligence on the part of the defendants, leading to death), and the rest were civil cases (claims for damages). Because the decision handed down in both criminal cases was "cause of death unknown", these defendants were found innocent. One of these cases was argued in both the court of appeals and the superior court: these courts found SIDS to be the cause of death and consequently the claim for damages was rejected. Both criminal and civil courts dealt with another case: the former found the cause of death to be "unknown" and the defendant innocent, while the latter, finding SIDS the cause of death, declined to review. In cases where the sleeping posture was prone, courts tended to decide the cause of death to be suffocation, especially with neonates. Because diagnosis by exclusion is required in cases of a legal autopsy for SIDS, the diagnosis is difficult without an autopsy. Disagreements between the results of legal autopsy and court decisions occurred in eight cases. With such a discrepancy, a detailed case examination is necessary. In 1983, SIDS was defined in Japan in two different ways; one in a more strict sense and the other being more inclusive. The wider and narrower definitions were unified in 1995 by requiring a survey of the circumstances of death in addition to the narrower definition. Because of this situation, the two cases in the 1980s when legal autopsy was not enforced fell into the category of "SIDS in a wider sense." In no case was a defendant found guilty when the cause of death was judged to be either SIDS/ALTE or unknown. Four cases were rejected when the cause of death was judged to be neither due to suffocation nor SIDS, while seven were accepted either as cases of "joint faults that canceled each other," or as "partial acceptance." In Japan, official views concerning a SIDS diagnosis differ among pediatricians, legal scholars of forensic medicine and pathologists. These differences appeared to influence the legal decisions. Several conferences should be convened as soon as possible to provide an opportunity to resolve the main points of difference between these three professional groups and, thus, attain a unified view.

Study to increase the frequency of autopsies performed for cases of infant deaths--proposed revision of the law on postmortem examination and corpse preservation and other related regulations.

By definition, sudden infant death syndrome (SIDS) requires diagnosis through exclusion by conducting an autopsy. To obtain a reliable diagnosis of this disease, an autopsy is essential. However, the frequency with which autopsies are conducted in Japan is not sufficient to meet the need associated with the diagnosis of SIDS. To improve this frequency, various public policies, such as nationwide implementation of the administrative autopsy system (medical examiner system), the application of the practice of autopsy approved by families, and legally required autopsies, are being considered; but none has been put into practice. On the other hand, attention has been called to the fact that the Law on postmortem examination and corpse preservation, which was instituted at the end of the Second World War, requires updating. In the current report, it is proposed that the following be added to Article 8, item 3 of this Law: "the Metropolitan or Prefectural Governor must insist that an autopsy be conducted on all cases of a sudden and unexpected death of an infant to investigate the cause of this death." At present, the annual incidence of SIDS in Japan is reported to be 500. To put the above-recommended legal requirement into practice, the estimated annual addition to the budget, if conducted as approved or an administrative autopsy, will be in the order of 150,000-500,000 dollar, which is within the prescribed limits for an appropriation.

[An epidemiological survey of sudden infant death syndrome in Tokyo].

OBJECTIVE: A complete autopsy is essential for an accurate diagnosis of sudden infant death syndrome (SIDS), whereas the autopsy rate is low in Japan. This study investigated the incidence of SIDS in Tokyo, where the autopsy rate for SIDS was the highest in Japan. METHODS: We selected death certificates of infants aged less than 2 years during 1990 to 1992 in Tokyo, whose cause of death was suspected to be SIDS, and classified those possibilities of SIDS according to death descriptions. RESULTS: The incidences of SIDS by strict definition and broad definition were 0.23 and 0.32 per 1,000 live births, respectively. Not a few death certificates described causes of death and death scene at some length. If including cases of suspected SIDS, the incidence came to 0.61 per 1,000 live births. The mortality risk of SIDS was significantly higher in infants with male gender and households classified by employment status as "other". Because the medical examiner system functioned only in the central urban area, most SIDS cases were diagnosed at autopsies in the urban area, whereas few cases were autopsied in the surrounding area. Compared to the urban area, the incidence of SIDS was significantly lower in the surrounding areas with low autopsy rates and with many death certificates of ambiguous death description. CONCLUSIONS: Ambiguous description of the death scene and low autopsy rate may cause under-diagnosis of SIDS. Establishment of a nationwide medicolegal autopsy system and examination of the death scene is necessary to diagnose SIDS accurately.

[Pathophysiological study of asphyxia and its applications to medico-legal diagnosis].

Asphyxia is commonly defined as "a hypoxic state in the body" which is caused by any one of a wide range of events, starting from an insufficiency of atmospheric oxygen to a failure in oxygen uptake by the cells. The present study outlines a physiopathological study of "mechanical asphyxia" various types of hypoxia caused by mechanical compression of the cervical and thoracic regions and its application to medicolegal diagnosis. We used an animal model in which an actual asphyctic condition was experimentally recreated. By elaborating the asphyctic mechanism through the physiological dynamics of the body fluids and tissues during the fatal process and the succeeding short time span, the study was intended to estimate the causes of death, time lapse after death before the examination, and the time of death in persons who were subjected to investigation, autopsy, or forensic examination. Our intention was also to establish medicolegal indices for the cause of death by examining patients who were resuscitated or expired before arrival (DOA). Our past superimental findings indicate that asphyxia is a state in which arterial blood gas anomalies (hypoxemia and hypercapnia) develop due to a disturbance in the respiratory mechanism, disrupting the maintenance of normal bodily functions by the organism. Among the clinical conditions of respiratory insufficiencies, asphyxia caused by external mechanical, factors (such as external application of pressure to the naso-oral, cervical, or thoracic region, insertion of a foreign body into the airway, and aspiration of fluids) corresponds to acute respiratory insufficiency due to hypercapnia type. In most of these cases with mechanical asphyxia, ventilatory insufficiency due to a lack of O2 in the inhaled air and insufficient removal of CO2 through expiration causes pulmonary alveolar hypoventilation and hyperemia associated with hypercapnia. Consequently, hypoxic hypoxia with systemic disturbances develops. The rapidity of development of the clinical events is correlated with the velocity of the rise in blood CO2 level and the development of acidemia from the early stage. The conditions culminate in non-compensatory (acute) respiratory acidosis. These abnormal physiological changes in turn produce symptoms such as congestion and cyanotic petechia. Asphyxia ensues if no resuscitation or other medical treatment is available during this stage (the so-called early asphctic stage). We believe that an understanding of these physiopathologic changes is useful in the diagnoses of asphyxia. It is also useful in the diagnosis of the above-cited process in cases of DOA and in patients who have received resuscitation or other medical treatment.

Medicolegal diagnosis of asphyxia--cerebral blood flow and brain oxygen tension.

Over the last several years, using rabbit models the authors analyzed cerebral blood flow (CBF), the brain oxygen tension (PtO2) and other physiological parameters during asphyxiation as means of achieving a practical diagnosis of asphyxiation. The author reports here on the effects of compression of the carotid arteries and obstruction of the airway leading to hypoxia, based on an analysis of CBF and PtO2 during hanging. Immediately after hanging, the CBF dropped but then rose suddenly. After several minutes, it dropped along with blood pressure. The PtO2 continued to decrease until the time of irreversible apnea. These findings suggest the effects of compression of the carotid arteries and the airway occlusion. After death, these results were confirmed with the injection-molded resin specimens of the airway and by the angiograph. But the closure of the vertebral arteries was not produced by the hanging.