Effect of dietary vitamin E on nitrite-treated rats

The effect of dietary vitamin E on cellular responses to nitrite was studied in rats. One-month-old male Sprague-Dawley rats were fed a basal vitamin E-deficient diet with or without 100 ppm vitamin E and 1000 ppm sodium nitrite (NaNO₂) for 9 weeks. In addition to a high mortality rate, nitrite-fed rats maintained on a vitamin E-deficient diet exhibited a marked increase in liver necrosis, tubular nephrosis and myodegeneration, as well as greater biochemical and hematological alterations when compared to the control animals. No animal mortality or histopathologic lesions in any tissues were observed in rats receiving a vitamin E-supplemented diet with or without nitrite. The results suggest that depletion of vitamin E renders rats more susceptible to the adverse effect of nitrite, and that nitrite administration potentiates deficiency of vitamin E in rats.     

Ferrihaemoglobin formation by amyl nitrite and sodium nitrite in different species in vivo and in vitro

The ferrihaemoglobin (HbFe³⁺) formation by amyl nitrite (AN) or sodium nitrite (NaNO₂) was studied in different species including man, in vivo and in vitro. In in vivo studies AN was administered intravenously (i.v.), intramuscularly (i.m.), by inhalation, or orally. NaNO₂ was injected i.v. AN i.v. produced HbFe³⁺ much more rapidly than NaNO₂ in dogs, cats, rabbits, and rats. In dogs, i.m. injection of AN was followed by a very slow linear increase in the HbFe³⁺ content. Inhalation of AN did not lead to HbFe³⁺ formation in dogs unless it was rebreathed in a closed (bag) or not completely open (gas mask) system. HbFe³⁺ was produced by oral AN in dogs, the effect being enhanced by addition of DMSO. Inhalation of AN by human volunteers in a gas mask and from ampoules crushed close to the nose did not induce haemoglobin oxidation to a practically significant extent, but it was associated with headache, tiredness, dizziness, and a fall in blood pressure. In in vitro studies, in contrast to NaNO₂, AN produced HbFe³⁺ instantaneously in erythrocytes of various species and in purified human haemoglobin. AN 1 mol yielded 2 mol Fe³⁺. Only 20% of the oxygen released during the oxidation of haemoglobin by AN or NaNO₂ was recovered. In 0.2 M phosphate buffer, pH 7.4, 0.01 mol O₂/mol AN was consumed. CO₂ was released in the presence of AN, but not of NaNO₂, from blood, plasma, and 0.02 M NaHCO₃ solution. The ratio (lactate)/(pyruvate) decreased when HbFe³⁺ was formed by AN or NaNO₂.     

泰安市售蔬菜中硝酸盐和亚硝酸盐含量的测定

<正> 蔬菜是易于富集硝酸盐的作物之一。White指出,人体摄取的硝酸盐81.2％来自蔬菜。Tremp认为,人体约有70％的硝酸盐是从蔬菜中摄取的。尽管硝酸盐本身对人体不具毒害性或毒害性较低,但它一旦被还原成亚硝酸盐之后,就有了潜在危险性。一方面亚硝酸盐易引起高铁血红蛋白症;另一方面它在适合的pH环境中,若有仲胺存在,就有可能发生     

Features of the hemodynamic response to amyl nitrite inhalation: Ew aspects of an old tool

Although amyl nitrite inhalation (ANI) antedates current short acting vasodilators as a clinically useful pharcologic stressor, few clinicians are aware of the subtle hemonamic actions of this agent. This study examined transients left and right heart hemodynamics after ANI in seven men ages 44 ± 7 years) undergoing elective cardiac catheterization. -fidelity central aortic (AoP), left ventricular (LVP), pulonary artery (PAP), right ventricular (RVP), and right atrial (PAP) pressures were simultaneously recorded from left and right heart multisensor catheters. As expected, ANI caused an fall in Ao pressure (27%; p<0.01) and reflex (p<0.001). Little change was noted in PAP, RVP, RAP, or end-diastolic pressures or the time constant of LV isovolnetric relaxation (tau). LV ejection time decreased 23 ± 10 (p<0.05) and RV ejection time did not change. Baroreflex was similar during pressure fall and recovery (6.4 ± vs. 6.1 ± 3.6 ms/mmHg), however hysteresis (p<0.05) was. Aortic pressure waveforms also changed following ANI. Changes were determined to be in part a consequence of the atanuation and delay in arterial wave reflections. This study the understanding of the complex nature of the hemodynamic response associated with ANI.     

Vasospasmogenic substance produced following subarachnoid haemorrhage,and its fate

Summary Fresh blood and supernatants of blood-CSF mixtures incubated for 1 to 15 days were applied to the basilar artery of adult cats, and the degree of constriction was measured with a surgical microscope. The constriction due to fresh blood was weak and transient. It seems possible to assume that serotonin isolated from platelets participates greatly in the transient vasoconstriction induced by fresh blood. Supernatants of blood-CSF mixtures incubated for three days had weak activity in comparison with the powerful and long-lasting activity of those incubated for seven days. Furthermore, mixtures incubated for 15 days had little or no activity. This change in the vasoconstrictive activity was similar to, and coincides chronologically with clinical late spasm following subarachnoid haemorrhage³⁴. We investigated the vasospasmogenic substance in the seventh day mixture. Heat coagulation, ultrafiltration, sephadex G-100 gel-chromatography, disc-electrophoresis, and Spectrophotography show that extracellular oxyHb has a strong spasmogenic activity. In the 15th day mixture, oxyHb is spontaneously converted to metHb.Experimentally, oxyHb has a strong vasoconstrictive activity, and metHb has no vasoconstrictive activity. We have had success in oxidizing oxyHb into metHb with sodium nitrite, thus preventing experimental vasospasm.     

Review: Putative mutagens and carcinogens in foods. IV. Malonaldehyde (malondialdehyde)

Malonaldehyde or malondialdehyde (MA) is an ubiquitous dietary constituent formed by the peroxidation of unsaturated fatty acids and of the food additive, sorbate. The average US citizen consumes between 0.2 and 0.6 μg of MA each day from fresh and processed meats alone. This figure might have been considerably higher in past decades when meat was packaged and stored under less optimal circumstances. No studies seem to have been performed to determine if free MA is released under physiological conditions, such as in simulated gastric juice. Although pure enzymologically synthesized MA is a weak mutagen for a new Salmonella frameshift tester strain containing a polyadenine sequence, reports of more pronounced mutagenicity and carcinogenicity are very likely erroneous. The impure chemically synthesized MA samples used in the strongly positive tests for genotoxic activity were contaminated with mutagenic methoxy-and ethoxyacroleins that would not be expected to constitute important components of foodstuffs. Thus, the greatest importance of MA and other carbonyls in foodstuffs may be their ability to catalyze nitrosation reactions in the presence of free nitrite and as indicators of the presence of other lipid oxidation products.     

催化光度法测定痕量亚硝酸根

基于亚硝酸根对氯酸钾氧化溴甲酚绿而使其褪色所起的催化作用，建立了高灵敏度催化光度法测定痕量亚硝酸根的新方法，测定范围为０．０８～０．６４μｇ／ｍｌ，用于硝酸钾和唾液中亚硝酸根的测定，结果满意。     

急性亚硝酸盐中毒患者ERP的研究

本文19例急性亚硝酸盐中毒患者72小时内进行视觉、听觉事件相关电位(ERP)测定结果表示,ERP中P_3波的潜伏期延长,而此时患者血糖值均降低。随着临床症状的好转,血糖值与P_3波潜伏期均恢复正常且两者有显著的相关性。本文对其机理进行初步探讨。     

Exhaled breath condensate nitrite/nitrate and pH in relation to pediatric asthma control and exhaled nitric oxide

BACKGROUND: Combining exhaled breath condensate (EBC) and exhaled nitric oxide (eNO) may be a useful, non-invasive method to assess airway inflammation in pediatric asthma. This cross-sectional study evaluated the relationship of both EBC nitrite/nitrate (NOx) and EBC pH with asthma control and eNO in asthmatic, normal, and atopic children. METHODS: A total of 92 children were recruited, comprising 62 with asthma, 14 with atopy only, and 16 who were normal and non-atopic. All completed a questionnaire for asthma symptoms and control. Variables measured were spirometry, EBC NOx, pH, and eNO. RESULTS: EBC NOx in those with asthma (mean 8.4 microM, CI 7.5-9.4) was significantly elevated when compared with normal (4.8 microM, CI 3.4-6.2, P = 0.0007) and atopic children (6.5 microM, CI 4.0-9.1, P = 0.02). The mean level of eNO was significantly higher in those with asthma (43.7 ppb, CI 34.7-51.1, P < 0.001) and atopy (24 ppb, CI 16.7-31.2, P < 0.05) when compared with normal children (11.5 ppb, CI 6.7-16.2). There was a significantly lower pH in those with asthma and a FEV(1) < 80% predicted (P = 0.03), but no significant overall differences in EBC pH between the three groups of children. There was a significant correlation between eNO and EBC NOx in the group as a whole, but not between eNO and EBC pH. CONCLUSIONS: Mean EBC NOx levels differ between children with asthma, atopy, and those who are normal, but it is not interchangeable with eNO. EBC pH may be an additional marker of asthma control.