A functional polymorphism of the micro-opioid receptor gene is associated with completed suicides.

A recent linkage study suggested that a putative locus for suicidal behavior independent of psychiatric disease phenotypes lies at 5' upstream of the micro-opioid receptor (OPRM1) gene. We explored an association between suicide and genetic variations of the OPRM1 using a case-control study of 183 completed suicides and 374 control subjects. We genotyped four single nucleotide polymorphisms (SNPs) including a common A118G SNP. The genotypic and allelic distributions of the A118G SNP were significantly different between the completed suicide and control groups (P = 0.014 and 0.039, respectively). A dominant model analysis of the A118G SNP showed an enhanced association with suicide (P = 0.0041, Odds ratio 0.575) and this significant association was observed with a logistic regression analysis that takes sex and age factors into account (P = 0.021). Our results raise the possibility that the A118G SNP of the OPRM1 gene is associated with suicide.

Association between a functional polymorphism in the renin-angiotensin system and completed suicide.

Suicide has been suggested to involve disturbances in the stress response system and to be related to genetics. The renin-angiotensin system (RAS) has been shown to affect the stress response, and several functional polymorphisms in RAS-related genes have been predicted to alter protein function. We hypothesized that the dysregulation of RAS was involved in suicide, and examined the association between completed suicides and four functional polymorphisms of RAS-related genes: the angiotensinogen M235T, angiotensin-converting enzyme (ACE) insertion(I)/deletion(D), angiotensin type-1 receptor A1166C, and G-protein-beta3 C825T gene polymorphisms. The I allele of the ACE I/D polymorphism was found to be more frequent in completed suicides than in controls (P = 0.014). The I allele was also found to be more frequent in male completed suicides (P = 0.022) than in male controls, while this was not the case in females. These results suggest that the alteration of RAS function caused by the genetic polymorphism is involved in the susceptibility to suicide in males.

Tryptophan hydroxylase immunoreactivity is altered by the genetic variation in postmortem brain samples of both suicide victims and controls.

Several lines of evidence suggest that a partly genetically controlled serotonergic dysfunction is involved in the biological pathogenesis of suicide. In this study, we measured tryptophan hydroxylase (TPH) immunoreactivity as a pre-synaptic marker, and serotonin receptor 2A (5HT2A receptor) density as a post-synaptic marker in the serotonergic system in 10 postmortem brains of suicide victims. We also examined whether TPH gene polymorphisms (A218C and A-6526G polymorphisms) could affect TPH immunoreactivity and 5HT2A receptor gene polymorphism (A-1438G polymorphism) could affect 5HT2A receptor density in 28 postmortem brain samples. No significant differences were found in TPH immunoreactivity or 5HT2A receptor density between suicide victims and controls. The AA genotype of the A218C polymorphism of the TPH gene showed higher TPH immunoreactivity along with lower 5HT2A receptor density than did any other genotypes in the postmortem brains of both suicide victims and controls. Our findings suggest that the A218C polymorphism of the TPH gene can be expected to provide new insights not only for neurobiological studies of suicide, but also for research into the behavioral characteristics that may be associated with serotonergic dysfunction.

Serotonin 2A receptor gene polymorphism is not associated with completed suicide.

Several lines of evidence indicate that a serotonergic dysfunction is involved in the biological susceptibility to suicide. Recently, the A-1438G polymorphism of the serotonin 2A (5-HT2A) receptor gene has been suggested to be associated with suicide, but the results are inconsistent. We examined whether the A-1438G polymorphism of the 5-HT2A receptor gene was associated with suicide itself using 151 Japanese completed suicides. No significant difference in genotype distribution or allele frequencies of the polymorphism was found between the completed suicides and the comparison group. We conclude that the A-1438G polymorphism of the 5-HT2A receptor gene is not likely to have a major effect on the biological susceptibility of suicide.

No evidence of an association between 5HT1B receptor gene polymorphism and suicide victims in a Japanese population.

Serotonergic systems have been reported to mediate the control of aggression and/or impulsivity in humans and to be involved in suicidal behavior. Neurochemical studies showing serotonergic dysfunction in suicide appear to support the functional alteration of serotonergic systems due to gene polymorphisms. Knock-out mice of the 5HT1B receptor gene have been reported to result in increased aggression. We hypothesized that the 5HT1B receptor-mediated serotonergic dysfunction was implicated in suicide through disinhibition of aggression and/or impulsivity. To explore this hypothesis, we examined the association between suicide victims who completed suicide and the 5HT1B receptor gene G861C polymorphism. No significant differences in genotype distribution and allele frequencies were found between suicide victims and controls. Though there is the possibility of failing to detect small effects, these results show no evidence of an association between the 5HT1B receptor gene G861C polymorphism and suicide victims in a Japanese population and indicate that it is unlikely that the 5HT1B receptor is implicated in the susceptibility to suicide.

Tryptophan hydroxylase gene polymorphisms are not associated with suicide.

Several lines of evidence suggest a serotonergic dysfunction involved in the biological susceptibility of suicide. Abnormalities of serotonergic markers such as 5-hydroxyindoleacetic acid and prolactin response to fenfluramine have been demonstrated in suicide subjects. Tryptophan hydroxylase (TPH), the rate-limiting enzyme in serotonin biosynthesis, is one of the most important regulating factors in the serotonergic system. Recently, polymorphisms of the TPH gene have been identified and some of these polymorphisms have been suggested to be associated with suicide, but the results are still inconsistent. We examined whether the -6526A/G polymorphism in the promoter region and the 218A/C polymorphism in intron 7 of the TPH gene were associated with suicide using 132 Japanese suicide victims. No significant difference in genotype distribution and allele frequencies of these polymorphisms was found between the suicide victims and the controls. We concluded neither the -6526A/G polymorphism nor the 218A/C polymorphism of the TPH gene is likely to have a major effect on the susceptibility of suicide. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:861-863, 2000.

An unusual case of suicide by stabbing with a falling weighted dagger.

An unusual suicide by self-stabbing is presented. A 42-year-old man committed suicide with a dagger weighted with 2.72 kg in total and allowed to fall freely. The blade of the dagger fell from a height of 10 cm above the chest, penetrated the second left intercostal skin and pierced the upper lobe of the left lung. However, the weapon did not penetrate the chest skin from a stationary position in our trial at the autopsy. This finding confirms the results of experiments with stab wound dynamics which demonstrated that the impact velocity of the weapon as well as the sharpness of the tip is important for skin penetration.

[An autopsy case of pulmonary thromboembolism associated with chlorine gas poisoning].

We report a rare case of sudden death of a patient with acute pulmonary thromboembolism associated with chlorine gas poisoning. A 21-year-old man in a water-filtration plant accidentally inhaled highly concentrated chlorine gas. He was immediately brought to a hospital after exposure. On admission, the patient had clouding of consciousness, dyspnea, and deep cyanosis. Arterial blood gas values indicated severe hypoxemia; PaO2 was 35.9 mmHg and PaCO2 was 42.4 mmHg. The clinical course was uneventful and he was satisfactorily recovering. However, ten days after admission he became sick and markedly cyanotic. He lost consciousness and then he went into cardiopulmonary arrest. Despite efforts at resuscitation, he died. An autopsy revealed bilateral pulmonary thromboembolism, although he apparently did not have any risk factor for embolism. The toxicity of chlorine gas may be related to the pulmonary thromboembolism, but the mechanisms leading to his death are unclear.

Changes in choice of method and lethality between last attempted and completed suicides: how did suicide attempters carry out their desire?

Some researchers have emphasized that, from the perspective of suicide prevention, research into the methods of suicide seemed to be particularly promising, as it has been shown repeatedly that restricting access to the prevailing method of suicide in a country will decrease suicide rates and that the lethality of the method used significantly correlated with the degree of intention to die. In this study, we examined changes in choice of method and the lethality score between the last attempted suicide (LAS) and completed suicide (CS) in 416 victims (male: 197, female: 219) to point out the tendency on their choice of method in LAS and CS. There was a significant difference in choice of suicide method between LAS and CS, and injury to themselves (33.7%) was the most common method of LAS, while hanging (37.5%) was the most common method of CS. The mean lethality score of CS method was significantly higher than that of LAS method in both sex groups, suggesting that at least one of the causes that drives suicide attempters to commit suicide finally may be the difference in the lethalities of LAS and CS. At the time of CS, suicidal victims tend to choose the same method as that of LAS again. These findings suggest that although suicide attempters tend to choose the same method, they will use a more lethal method if they change the suicide method. Interestingly, moreover, there was no sex difference in the percentage of the mean lethality score at CS.

[An autopsy case of sudden death due to Chagas' disease].

An autopsy case of sudden death of a 41-year-old male Brazilian with Chagas' disease in reported. In his life time, right handle branch block and ventricular premature contractions were marked in electrocardiogram. Autopsy revealed striking dilatation of both cardiac ventricles. Histopathologically, extensive myocardial fibrosis due to chronic interstitial myocarditis was observed. On myocardial tissue preparation performed Giemsa's stain, leishmania foci of Trypanosoma crusi were detected around the myocardial fibrosis.