Two-generation reproductive toxicity study of tributyltin chloride in male rats.

A 2-generation reproductive toxicity study of tributyltin chloride (TBTCl) was conducted in male rats using dietary concentrations of 5, 25, and 125 ppm TBTCl to evaluate its effect on sexual development and the reproductive system. F1 males were killed on postnatal day 119 and F2 males were killed on postnatal day 91. TBTCl affected the male reproductive system of rats. The weights of the testis and epididymis were decreased and homogenization-resistant spermatid and sperm count were reduced mainly in the 125 ppm TBTCl group. Histopathologic changes were also observed in the testis of this group and included vacuolization of the seminiferous epithelium, spermatid retention, and delayed spermiation. However, the changes were minimal in nature. The weight of the ventral prostate was decreased to 84% of the control value in the 125 ppm group in the F1 generation and decreased to 84 and 69% of the control value in the 25 ppm and 125 ppm TBTCl groups, respectively, in the F2 generation. The serum 17beta-estradiol concentration was also decreased to 55% of the control value in the 125 ppm group in the F1 generation and decreased to 78 and 57% of the control value in the 25 ppm and 125 ppm TBTCl groups, respectively, in the F2 generation. However, the serum concentrations of luteinizing hormone (LH) and testosterone were not decreased in these groups. These changes corresponded with those caused by aromatase inhibition and therefore TBTCl might be a weak aromatase inhibitor in male rats.

Two-generation reproductive toxicity study of tributyltin chloride in female rats.

A two-generation reproductive toxicity study of the effects of tributyltin chloride (TBTCl) was conducted in female rats using dietary concentrations of 5, 25, and 125 ppm TBTCl. Reproductive outcomes of dams (number and body weight of pups and the percentage of live pups) and the growth of female pups (the day of eye opening and body weight gain) were significantly decreased in the 125 ppm TBTCl group. A delay in vaginal opening and impaired estrous cyclicity were also observed in the 125 ppm TBTCl group. However, an increase in anogenital distance was found in all TBTCl groups on postnatal d 1. A dose-effect relationship was observed in TBTCl-induced changes in anogenital distance. These results indicate that the whole-life exposure to TBTCl affects the sexual development and reproductive function of female rats. In addition, the TBTCl-induced increase in anogenital distance seems to suggest it may exert a masculinizing effect on female neonates. However, the concentrations of TBTCl used in this study are not environmentally relevant.

Genetic risk factors for coronary artery spasm: significance of endothelial nitric oxide synthase gene T-786-->C and missense Glu298Asp variants.

BACKGROUND: We recently identified two endothelial nitric oxide synthase (eNOS) gene polymorphisms, Glu298Asp and T-786-->C, which are independently associated with coronary spasm. eNOS gene intron 4b/a polymorphism is also reported to be involved in smoking-dependent coronary artery disease. The genetic linkage among these polymorphisms remains unknown. Also, it is unclear which variant is most responsible for coronary spasm. In the present study, we first examined the genetic linkage among these three variants. Next, we studied the risk factors of coronary spasm by using all significant genetic and conventional risk factors in a large-scale study. METHODS: The genotype and allele frequencies for the T-786-->C, intron 4b/a, and Glu298Asp variants were assessed in 423 randomly selected DNA samples to examine their genetic linkages. The relative capacities of all risk factors to predict coronary spasm were then analyzed using multiple logistic regression in 201 patients with coronary spasm and 345 volunteers. RESULTS: Comparison of allele frequencies revealed that the eNOS intron 4a allele was significantly linked to the T-786-->C mutation (P < 0.00001), whereas there was not a linkage between the intron 4a allele and the Glu298Asp variant (P = 0.1437) or between the Glu298Asp variant and the T-786-->C mutation (P = 0.1996). Multiple logistic regression revealed that the most predictive independent risk factor for coronary spasm was the T-786-->C mutation (P < 0.001), followed by cigarette smoking (P < 0.001), hypertension (P = 0.004), and the Glu298Asp variant (P = 0.028). CONCLUSIONS: We found that the T-786-->C mutation and the intron 4a allele are in linkage disequilibrium. We previously showed that the T-786-->C mutation reduced eNOS gene promoter activity. In that context, our results strongly suggest that the T-786-->C mutation underlies the functional characteristics of the intron 4a allele. Further, multiple logistic regression analysis revealed that the T-786-->C mutation is the most predictive risk factor for coronary spasm, followed by cigarette smoking. Given that those effects are potentially additive, patients carrying the eNOS gene variants should be strongly cautioned against smoking.

Comparison of the risk factors for coronary artery spasm with those for organic stenosis in a Japanese population: role of cigarette smoking.

We compared the risk factors for coronary spasm with those for coronary atherosclerosis in 183 patients with coronary spasm, 132 patients with coronary organic stenosis, and 224 control subjects with chest pain syndrome. Our findings confirmed that, when compared with controls, age, gender, total cholesterol, LDL-cholesterol, hypertension, diabetes mellitus, and cigarette smoking are all significant risk factors for coronary organic stenosis. On the other hand, only cigarette smoking proved to be a significant risk factor for coronary spasm. Also, when compared between coronary spasm group and coronary organic stenosis group, the incidence of cigarette smoking in males was significantly higher in the coronary spasm group than in the coronary organic stenosis group. We conclude that cigarette smoking is a crucial risk factor for coronary spasm. On the other hand, serum lipid levels and the incidence of hypertension and diabetes mellitus were within the normal ranges in the coronary spasm patients and were thus poorly associated with coronary spasm. These results showed that the risk factors for coronary spasm differ significantly from those for atherosclerosis-based coronary stenosis in the Japanese. Among the risk factors for coronary atherosclerosis (organic stenosis) smoking alone was a significant preventable risk factor for coronary artery spasm.

A T-786-->C mutation in the 5'-flanking region of the endothelial nitric oxide synthase gene and coronary arterial vasomotility.

In the endothelium, synthesis of nitric oxide (NO) from the amino acid L-arginine is catalyzed by the endothelial NO synthase (eNOS), and the continuously generated NO serves to maintain basal vascular tone. Recently, we discovered a T-786-->C mutation in the 5'-flanking region of the eNOS gene; this mutation reduced the promoter activity of the eNOS gene and was associated with coronary spasm. We examined the vasomotility of the epicardial coronary artery in subjects with and without T-736-->C mutation. We examined vasomotility in 32 consecutive subjects who were heterozygotes for the T-786-->C mutation and in 68 subjects without the T-786-->C mutation who had equivalent age, sex, and smoking status at the proximal and distal segments of the left descending coronary artery by performing quantitative coronary angiography. In subjects with the mutant allele (-786C allele), basal diameters of proximal and distal segments before intracoronary injection of acetylcholine (ACh) were less than diameters in subjects without the mutant allele (p <0.05), although there was no difference between subjects with and without the mutant allele in the diameters of coronary arteries after isosorbide dinitrate (ISDN) administration. When we compared the changes in diameters, both ACh-induced vasoconstriction and ISDN-induced vasodilatation in subjects with the mutant allele were significantly increased in the proximal (p <0.01, p <0.001, respectively) and distal segments (p <0.03, p <0.01, respectively). Taken together, these findings strongly suggest that the T-786-->C mutation increases the basal tone of the coronary artery, and enhances the response to the constrictor effects of ACh and the dilator effect of ISDN because of reducing the endothelial NO synthesis.

Association of the missense Glu298Asp variant of the endothelial nitric oxide synthase gene with myocardial infarction.

OBJECTIVES: We examined the possible association between the missense Glu298Asp variant of the endothelial nitric oxide synthase (eNOS) gene and myocardial infarction (MI). BACKGROUND: Endothelium-derived nitric oxide (NO) plays a key role in the regulation of vascular tone. Recently, we reported that a missense Glu298Asp variant in exon 7 of the eNOS gene is a possible genetic factor involved in the pathogenesis of coronary spasm. Endothelium-derived NO also has vasoprotective effects by suppressing platelet aggregation, leukocyte adhesion and smooth muscle cell proliferation. METHODS: We screened 285 patients with an MI and 607 control subjects in Kumamoto Prefecture, Japan. Genotypes were determined by polymerase chain reaction-restriction fragment-length polymorphism analysis. RESULTS: The frequency of the missense Glu298Asp variant was significantly higher in the MI group than in the control group (21.1% vs. 13.3%, p = 0.003, odds ratio 1.73 for the dominant effect of the eNOS T allele). Multiple logistic regression analysis showed that the missense Glu298Asp variant was an independent risk factor for MI, as was diabetes mellitus, hypertension, cigarette smoking, hypercholesterolemia and body mass index. CONCLUSIONS: There was a significant association of the missense Glu298Asp variant of the eNOS gene with MI. This marker-disease association may be due to the impaired effects of NO on the cardiovascular system: dysregulation of vascular tone, platelet aggregation and leukocyte adhesion and smooth muscle cell proliferation, all of which promote coronary atherosclerosis and thrombosis.

[Electromyographic study of the canine stomach after transection and mucosal bridge anastomosis (author's transl)].

In order to clarify the propagation mechanism of canine gastric electrical activity, the stomach was transected and reanastomosed at the middle antrum in 3 dogs and at the distal corpus in 3 dogs. Two bipolar electrodes were implanted in the pre- and postanastomosis stomach. Electromyographic recordings were performed intermittently for 8 to 13 weeks in fasting and after feeding. In one of the 6 dogs, 11 weeks after the initial surgery, one half of the anterior muscle wall of the greater curvature side was reapproximated. In fasting, the BER interval in the preanastomosis remained unchanged, but that in the postanastomosis became prolonged. After feeding, the BER interval in the postanastomosis was shortened and showed an advancement to close to that in the preanastomosis. 3 weeks after reapproximation of partial muscle wall, the BER interval in the postanastomosis recovered to the same BER interval as in the preanastomosis in fasting and after feeding stages. Dysrhythmia in the postanastomosis was of temporal occurrance. These results suggest that an inherent automatism in the gastric wall plays a role in the recovery of the BER interval and close muscle approximation is essential for propagation of gastric electrical activities.