Sudden Death in Infancy: A Study of Cardiac Specialized Tissue

The hearts from 15 cot death patients have been compared with those of 15 controls. In one of the cot death patients an accessory atrioventricular connexion known to be capable of producing ventricular pre-excitation and sudden death was identified. In all hearts examined additional segments of specialized tissue were found in relation to the atrioventricular orifices which may have been significant in producing pre-excitation. Haemorrhagic lesions were present in the atrial myocardium and conducting tissues of hearts from both groups, but no evidence was found of cellular degeneration in the atrioventricular bundle. There is a need for further studies of conducting tissues in sudden death syndromes.     

A new look at the neonatal electrocardiogram.

Among 818 newborn babies whose electrocardiograms (ECGs) were recorded between April 1975 and April 1976 were 57 babies with recordings that fell outside the accepted normal range. Preliminary observations have identified the need to define more clearly the range of normal variation. Twelve babies showed asymptomatic conduction abnormalities, three of which were thought sufficiently serious to need treatment. Two babies died suddenly, one of whom had abnormal conduction on the ECG and histologically demonstrated abnormalities of the conducting system. This continuing prospective study may indicate a link between conducting tissue abnormalities and the sudden infant death syndrome. Ten babies had congenital cardiac anomalies, four of which were first discovered because of an abnormal screening cardiogram. Electrocardiography, a simple and noninvasive procedure, may be a valuable addition to the routine neonatal examination.     

Root to leaf electrical signaling in avocado in response to light and soil water content

Phytomonitoring techniques for irrigation of avocado orchards indicate that plants respond very rapidly to fluctuations in soil water content. Root to leaf abscicic acid transport cannot fully explain the almost immediate response of stomata to either irrigation and/or sudden changes in climatic conditions. Therefore, we studied the existence of a fast conducting signal between roots and leaves, and the possible involvement of such a signal in the regulation of stomatal behavior. Two-year-old avocado trees were subjected to drying and re-watering cycles or changes in incident radiation (light or darkness). The difference in extracellular electrical potential between the leaf petiole and the base of stem (DeltaV(L-S)) was continuously recorded. Stomatal conductance (gs) was also recorded for the same leaves that were used for voltage difference measurements. A sudden change in soil water content induced by root drying and re-watering was accompanied by a slow, significant change in the recorded DeltaV(L-S) signal, which was fully developed at 52 and 32min for root drying and re-watering, respectively. We found an inverse correlation (r=-0.56) between the change of DeltaV(L-S) and the gs difference measured before and after each soil-drying treatment. Plants that were girdled to disrupt the phloem and then irrigated tended to have lower DeltaV(L-S) differences over time than non-girdled irrigated plants, suggesting that the electrical signal was transmitted in the phloem. The existence of a fast signal transmitted from the root to the leaf that can be measured and correlated with stomatal control opens the possibility of developing a new phytomonitoring technique and/or artificially modifying plant responses by imposing agronomic management strategies aimed at rapid stomatal adaptation to changes in soil water content.     

突发性公共卫生事件中法医工作者的角色探究

突发性公共卫生事件已经成为当前人类社会面临的一项重大难题和挑战。在应对和处置各类突发性公共卫生事件法医工作者被社会和国家赋予了重要的义务和责任。本文对法医工作者在解决各类突发性公共卫生事件中的角色定位进行了探讨,阐明法医工作者在应对和处置突发性公共卫生事件中发挥的重要作用。同时,针对现在和未来突发性公共卫生事件的发生发展趋势,对法医工作者在应对和处置这些事件中的角色作用提出了展望,并对法医工作者如何来提高自身的综合业务能力和素质,以便更好地来扮演好在突发性公共卫生事件中的角色。     

Circadian variation of abnormal heart beats in an elderly population and their relation to sudden cardiac death.

The relationships between the circadian variation of abnormal heart beats and the circadian variation in sudden cardiac death warrant further discussion for the high correlations demonstrated here are difficult to ignore. In the healthy group abnormal beats showed a high correlation of their circadian variation with that of sudden cardiac death which is independent of heart rate. As a result the conclusion that the relationship of the circadian variations of abnormal heart beats and sudden cardiac death is merely dependent on a mutual dependence on activity is not supported here. The present data illustrates a strong association between arrhythmias and sudden cardiac death. The relationship of sudden cardiac death with abnormal heart beats demonstrated here, however, cannot confirm a causal role of the latter on the former for both may be responding to circadian variations of some underlying mechanism such as ischemia. Additionally the population studied here, although relatively comparable in terms of living conditions and other significant factors, was not strictly age-matched with those from the sudden cardiac death study warranting further caution in interpreting the association demonstrated here. The results from the unhealthy group, although somewhat limited, indicate that cardiovascular morbidity may alter the relationship of sudden cardiac death and abnormal heart beats. Such a result could be explained by the presence of other forms of heart disease which could be responsible for sudden cardiac death in the unhealthy group. An interesting question to ask concerning the data presented above is whether or not significant circadian variations in in the frequency of abnormal heart beats could have been demonstrated when exogenous factors such as meal times and activity were altered. The data on in hospital sudden cardiac death indicates that the circadian variation in sudden cardiac death is significantly altered by the radical changes in routine which accompany hospitalization. If the relationship between the circadian variation of sudden cardiac death and abnormal heart beats is as strong as the results presented here indicate, it is likely that the alteration of such exogenous factors would also change the circadian variation of abnormal heart beats. The results of the present study indicate that both the circadian variation in abnormal heart beats, and its relationship to sudden cardiac death, warrant further study.     

Circulating KCNH2 current-activating factor in patients with heart failure and ventricular tachyarrhythmia

Background

It is estimated that approximately half of the deaths in patients with HF are sudden and that the most likely causes of sudden death are lethal ventricular tachyarrhythmias such as ventricular tachycardia (VT) or fibrillation (VF). However, the precise mechanism of ventricular tachyarrhythmias remains unknown. The KCNH2 channel conducting the delayed rectifier K⁺ current (I_Kr) is recognized as the most susceptible channel in acquired long QT syndrome. Recent findings have revealed that not only suppression but also enhancement of I_Kr increase vulnerability to major arrhythmic events, as seen in short QT syndrome. Therefore, we investigated the existence of a circulating KCNH2 current-modifying factor in patients with HF.

Methodology/Principal Findings

We examined the effects of serum of HF patients on recombinant I_Kr recorded from HEK 293 cells stably expressing KCNH2 by using the whole-cell patch-clamp technique. Study subjects were 14 patients with non-ischemic HF and 6 normal controls. Seven patients had a history of documented ventricular tachyarrhythmias (VT: 7 and VF: 1). Overnight treatment with 2% serum obtained from HF patients with ventricular arrhythmia resulted in a significant enhancement in the peaks of I_Kr tail currents compared to the serum from normal controls and HF patients without ventricular arrhythmia.

Conclusions/Significance

Here we provide the first evidence for the presence of a circulating KCNH2 channel activator in patients with HF and ventricular tachyarrhythmias. This factor may be responsible for arhythmogenesis in patients with HF.     

CRT_D介导室性心动过速的研究进展

心室再同步心脏转复除颤器（CRT）可有效改善心力衰竭（CHF）患者的运动耐量和生活质量,预防猝死,提高生存率,但_DCHFCRTD植入后由于心室激动顺序的改变,使QT间期延长、跨室壁复极离散度（TDR）增加,潜在致室性心律失常风险;且CHF患者通常存在心肌解剖改变,传导的不均一性,也为折返性心动过速的发生提供了维持的机制;而多次电击也可导致肌钙蛋白升高,引起心肌损伤,局部心肌复极离散度增加（DRVR）和QT间期延长,以及电除颤后心肌纤维化和急性细胞损伤,反复室速、室颤也会引起进行性左心功能不全、心肌细胞凋亡、恶化心律失常基质和增加心律失常易感性。CRT_D潜在致室性心律失常作用逐渐引起人们的重视,本文就近年来CRTD致室性心律失常的电生理机制与临床防治对策等做一综述。     

Immunological evidence for a bacterial toxin aetiology in sudden infant death syndrome

Toxin-specific antibodies to clostridial, enterobacterial and staphylococcal toxins implicated in sudden infant death syndrome were studied in sera from sudden infant death syndrome infants and a comparison group of infants (babies with phenylketonuria). The results indicated a higher proportion of sera from sudden infant death syndrome infants contained IgA that bound to clostridial and enterobacterial toxins but a higher proportion of sera from the phenylketonuria comparison group contained IgA that bound staphylococcal toxins. The higher proportion of serum samples with IgG and IgM in the healthy comparison babies serum probably indicated immunity in this group of babies to these toxins. The effect of gender and age had a minimal effect on the incidence of these antibodies. The presence of toxin-specific antibodies in sudden infant death syndrome and the of comparison infants suggests that all infants are exposed to these toxins and most babies successfully overcome the toxic challenge. Some infants with predisposing risk factors (temperature change, smoking, infection, immune development, sleeping position, etc.) that could affect the baby's immune competency could succumb to these and possibly other toxins. This immunological evidence further strengthens the view that bacterial toxins are a significant cause of sudden infant death syndrome.     

Omega-3 consumption and sudden cardiac death in schizophrenia

People with schizophrenia show a two- to three-fold increased risk to die prematurely. Mortality is accounted for by a combination of factors (patients’ life style, suicide, premature cardiovascular disease, metabolic syndromes and, not so often mentioned, sudden death). The cause of sudden death in schizophrenia is unknown, but cardiac arrhythmia plays a potential role. Patients with schizophrenia are at high risk for cardiovascular disease, and some antipsychotics may be associated with cardiovascular adverse events (e.g., electrocardiograph QT interval prolongation), suggesting that this could lead to sudden cardiac death. Animal and clinical studies have shown that omega-3 fatty acids could be useful in the prevention and treatment of schizophrenia. As omega-3 fatty acids have been considered a cardioprotector agent, reducing cardiac arrhythmias and hence sudden cardiac deaths and given their relative safety and general health benefits, our update article summarizes the knowledge by the possible positive effects of omega-3 supplementation and fish consumption against sudden cardiac death in patients with schizophrenia. However, fish species should be selected with caution due to contamination with toxic methylmercury.     

Neurobiology of Stomotoca. II. Pacemakers and conduction pathways.

Evidence is presented for separate conduction pathways for swimming and for tentacle coordination in the marginal nerves of the jellyfish Stomotoca. The effector muscles are fired through junctions sensitive to excess Mg++, probably represented by the neuromuscular synapses observed by electron microscopy. The swimming effector (striated muscle) fires one-to-one with nerve input signals and myoid conduction occurs. Tentacle responses (smooth muscle contractions) involve facilitation, presumably at the neuro-effector junction; responses are graded and nonpropagating. Electrical correlates of two further conducting systems using the marginal nerves have been recorded. Their functions are unknown. One, the bridge system, extends up the four radii and encircles the peduncle; the other (ring system) is confined to the margin. A fifth conducting system is inferred in the case of the pointing response and its distribution is plotted. Signals have not been obtained from it. Pointing is accompanied by a burst of muscle potentials in the radial smooth muscles and is exhibited after a lengthy latency, indicating a local pacemaker. A sixth conducting pathway is the epithelial system, which mediates crumpling, a response involving the radial muscles without pacemaker intervention. Characteristic conduction velocities and wave forms are noted for the first four systems and for epithelial pulses. All systems, except perhaps the pointing conduction system, through-conduct under excess Mg++. Spontaneous activity patterns are described for the swimming, tentacle pulse, and ring systems. Abrupt increases in light intensity inhibit spontaneous activity, sudden decreases augmenting it. In the absence of specialized photoreceptors, light is presumed to act directly on central neurons. Epithelial pulses inhibit swimming, apparently by blocking the generation or conduction of the primary nervous events. This observation, taken in conjunction with evidence of feedback inhibition of the primary swimming system by the cells it fires, is discussed in relation to possible mechanisms whereby the output of nerve cells might be altered by activity in the excitable epithelial cells which envelop them.     

Skeletin immunoreactivity in heart Purkinje fibers from several species.

Ever since its discovery, the identification of the specialized conducting system of the heart has been a matter of debate. In some species, a main distinguishing feature under the electron microscope, as compared with ordinary myocytes, is the presence of large pools of juxtanuclear filaments, so called intermediate or skeletin filaments. In the present study, we have adopted the indirect immunofluorescence method and anti-skeletin antisera for the identification of the ventricular conducting system in several species. It was found that anti-skeletin reactivity generally exceeded that of ordinary myocytes. The degree of immunofluorescence could be related to a previous classification model of the differentiation of the conducting cells. It is suggested that skeletin is highly conserved throughout phylogeny and that anti-skeletin may serve as an additional tool for the identification of conducting cells at the light microscopic level.     

Blockade of thromboxane and the prevention of eicosanoid-induced sudden death in mice

We studied the effects of thromboxane-receptor antagonism and thromboxane synthetase inhibition in a thrombotic model of sudden death in mice. Intravenous injection of arachidonic acid (AA; 80 mg/kg) or the prostaglandin-endoperoxide analog U-46,619 (2.3 mg/kg) results in sudden death in approximately 90% of the animals. Pretreatment with the thromboxane receptor antagonist SQ-29,548 (0.3-10 mg/kg) protects dose-dependently against AA and U-46,619-induced sudden death. In contrast, CGS-13,080, a thromboxane synthetase inhibitor, shows a dose-dependent beneficial effect in AA-induced sudden death only. Although PTA2 has partial thromboxane agonistic properties in the rabbit, it protected the mice against AA-induced sudden death, thus demonstrating TxA2 antagonistic properties in this species. These data emphasize the importance of thromboxane A2 as a major mediator of arachidonic acid-induced sudden death and the effectiveness of thromboxane-receptor antagonists in endoperoxide-induced sudden death.     

Lung immunoglobulins in the sudden infant death syndrome.

The incidence of the sudden infant death syndrome parallels that of respiratory tract infections in the paediatric community. On the basis that the aetiology of the sudden infant death syndrome may lie in an unusual response to a trivial intercurrent respiratory infection a necropsy study was carried out investigating pulmonary immunoglobulins in 16 victims of the syndrome and a series of infants (controls) who had died of non-pulmonary causes. Compared with the controls victims of the sudden infant death syndrome had grossly raised concentrations of IgG, IgM, and to a less extent IgA in lung lavage samples. In addition, pulmonary interstitial and terminal airway cells expressing these immunoglobulins were identified far more often in victims than controls. The study failed to determine whether the increased immunoglobulin concentrations were a consequence of an unusual response to a trivial infection or an expression of otherwise altered immunological control in the respiratory tract. Epidemiological evidence and the findings of this study suggest that the respiratory tract is the prime target organ in the sudden infant death syndrome.     

Ethnic differences in mortality from sudden infant death syndrome in New Zealand.

OBJECTIVES--To examine the factors which might explain the higher mortality from sudden infant death syndrome in Maori infants (7.4/1000 live births in 1986 compared with 3.6 in non-Maori children). DESIGN--A large nationwide case control study. SETTING--New Zealand. 485 infants who died of sudden infant death syndrome were compared with 1800 control infants. There were 229 Maori and 240 non-Maori cases of sudden infant death syndrome (16 cases unassigned) and 353 Maori and 1410 non-Maori controls (37 unassigned). RESULTS--Maori infants had 3.81 times the risk (95% confidence interval 3.06 to 4.76) of sudden infant death syndrome compared with non-Maori infants. The risk factors for sudden infant death syndrome within groups were remarkably similar. When Maori and non-Maori controls were compared the prevalence of many of the known risk factors was higher in Maori infants. In particular, mothers were socioeconomically disadvantaged, younger, and more likely to smoke and their infants were of lower birth weight and more likely to share a bed with another person. Multivariate analysis controlling for potential confounders found that simply being Maori increased the risk of sudden infant death syndrome by only 1.37 (95% CI = 0.95 to 2.01), not statistically significantly different from 1. Population attributable risk was calculated for prone sleeping position, maternal smoking, not breast feeding, and infants sharing a bed with another person. In total these four risk factors accounted for 89% of deaths from sudden infant death syndrome in Maori infants and 79% in non-Maori infants. CONCLUSION--The high rate of sudden infant death syndrome among Maori infants is based largely on the high prevalence in the Maori population of the major risk factors. Other risk factors, not related to ethnicity, probably explain remaining differences between Maori and non-Maori children.     

Sudden cardiac death after repair of anomalous origin of left coronary artery from right sinus of Valsalva with an interarterial course

Anomalous aortic origin of the coronary artery from the opposite sinus with interarterial course (AAOCA) is a rare condition with a high risk of sudden cardiac death (SCD) during or after strenuous exertion. SCD after repair of this anomaly is extremely rare. Here we present a 15-year-old athlete who collapsed on the basketball court in whom an anomalous origin of the left coronary artery from the right sinus of Valsalva with interarterial course (ALCA) was diagnosed. In spite of extensive pre-sport participation testing, SCD occurred shortly after surgical correction. We reviewed the literature to establish an evidence-based recommendation to aid physicians in conducting the optimal pre-sport participation management for the prevention of SCD in patients with a surgically corrected AAOCA/ALCA, especially for those who participate in strenuous exercise. Review of the literature (60 articles with 325 patients) reveals that post-surgical, pre-sport participation testing varies greatly but that mortality after surgical repair is extremely low (1.5 %). In conclusion, SCD can still rarely occur after repair of AAOCA despite extensive pre-sport participation testing. This should raise awareness among physicians treating these patients and raises the question whether or not return-to-play guidelines need to be revised.     

Server-based teleconsultation in lung pathology

We report a rare case of ostial plication as a potential cause of sudden death. Very few reports and images are available in the specialized literature regarding this anomaly. Ostial plication may be a source of sudden death or cause of death when no other significant autopsy findings are present. Ostial plication is a congenital severe obstruction/occlusion of the right or left ostium. Plication of the aortic wall leads to a "valve-like" ridge that can act as a door blocking inflow during diastolic filling, with consequent ischemia and a potentially life-threatening arrhythmia. The true incidence of this condition and its relationship to sudden death have not been reported in the literature. We believe that this case will be useful to autopsy pathologists in detecting this infrequent anomaly, thus providing a more accurate estimation of its incidence.     

Preliminary investigation of lethally toxic sera of sudden infant death syndrome victims and neutralisation by commercially available immunoglobulins and adult sera

The aim of the study was to test the hypotheses (i) that sudden infant death syndrome sera are toxic to 11-day old chick embryos and (ii) that such a toxicity can be counteracted by immunoglobulin or adult sera. Serum samples from 11 SIDS victims and five controls were tested for lethal toxicity in the chick embryo bioassay. Five serum samples were used to challenge chick embryos injected with the following: sudden infant death syndrome serum plus Hank's balanced salt solution; Hank's balanced salt solution alone; sudden infant death syndrome serum plus 3% w/v commercial immunoglobulin; sudden infant death syndrome serum plus 6% w/v immunoglobulin; sudden infant death syndrome serum plus pooled sera of 40 healthy adults. Results obtained revealed that Hank's balanced salt solution, the pooled adult serum and the commercial immunoglobulin were all non-lethal, in the chick embryo test system. By contrast. 10 sudden infant death syndrome victims yielded sera containing lethal levels of toxin(s) compared to 2/5 controls which was statistically significant (P < 0.05, Fischer's exact test). In the tests of sudden infant death syndrome serum plus immunoglobulin or pooled adult serum, the lethality of sudden infant death syndrome serum was abolished in all cases. The reduction in toxicity of individual sudden infant death syndrome serum plus immunoglobulin or pooled adult serum was often statistically significant (P<0.05-P<0.00005, Fischer's exact test). We conclude that lethal levels of toxin are present in sudden infant death syndrome sera and that they can be neutralised by normal immune serum. These results indicate that passive immunisation is a potential treatment to protect babies considered at risk from sudden infant death syndrome.     

心源性猝死者窦房结病理学观察和HCN4、CX45的表达及其意义

目的:研究心源性猝死者窦房结病理学改变和超级化激活环核苷酸门控阳离子通道基因4(HCN4)、缝隙连接蛋白45(Cx45)的表达.方法:实验组为21例心源性猝死者,对照组18例(交通事故损伤致死9例,心脏破裂4例,肝破裂3例,脾破裂2例).经HE染色观察窦房结的形态学变化;应用免疫组化检测HCN4和Cx45在窦房结的表达.结果:心源性猝死组HCN4的表达高于对照组(P＜0.05),心源性猝死者窦房结Cx45的表达明显低于对照组(P＜0.01).结论:窦房结病理改变是引起心源性猝死的重要原因之一,HCN4表达的增高和Cx45表达的减少与心源性猝死的发生有一定的相关性.     

Observations in five cases of spontaneous cerebellar hemorrhage

Five cases of spontaneous intracerebellar hemorrhage are reported. Three had a vascular malformation and two had mild hypertension. The presenting symptom was sudden headache followed by nausea and vomiting. Signs of brain stem dysfunction without prominent cerebellar deficit were the commonest feature. Meningeal involvement was present in the majority of cases. Unsuspected sudden death can occur. It is suggested that patients below the age of 30 who present with sudden headache followed by brain stem dysfunction with or without a subarachnoid hemorrhage, and patients over the age of 45 who present this picture along with subarachnoid hemorrhage should be investigated urgently with contrast studies for possible cerebellar hemorrhage.     

Anatomical significance of the hygrochastic movement in Anastatica hierochuntica

BACKGROUND AND AIMS: Unlike the dispersal mechanisms of many desert plants, the whole dead skeleton of Anastatica hierochuntica is involved in seed dispersal and preservation. This process depends on the hygrochastic nature of the lignified conducting tissue that bends when dry and straightens under wet conditions. An anatomical interpretation of this mechanical movement was investigated. METHODS: An anatomical study of the stem was conducted on the juvenile plants raised under different water treatments and on the branch-orders of adult A. hierochuntica size-classes. KEY RESULTS: In the juvenile stem of A. hierochuntica, the area of cortex, conducting tissue and pith increased with water availability. However, the hydraulic conductance decreased, resulting in a better withdrawal of water in water-stressed plants. The anatomical investigation of the hygrochastic mechanism revealed an asymmetric distribution of the cortical tissues, with the conducting tissues of the stem of juvenile and adult plants being larger in the lower side. The hydraulic conductance was better in the basal and middle branch-orders than the terminal ones, permitting better conductance of water to the subsequent branch-orders. CONCLUSIONS: The lignified conducting tissue of the whole stem, having a hygrochastic nature, controls the movement of the branches. The greater amount of conducting tissue associated with a higher density of wide xylem vessels was observed in the lower side of the stem as compared with the upper side. Consequently, the conducting tissue in the lower side of the stem was suggested to be more effective in the opening process of the curled dry branches through better and more rapid conductance of water. Alternatively, due to the few narrow xylem vessels in the upper side of the stem, it was likely that the conducting tissue in the upper side is more effective in the closing process by providing more rapid drying. The mechanical rise of water and the related hygrochastic efficiency were maximized in the basal and middle branch-orders that are mostly involved in the mechanical movement.