Development of new method for the diagnosis and treatment of halitosis on several odor-causing agents

口臭起源于口腔内的微生物腐烂，挥发性硫化合物（VSCs）被认为是与口臭相关的主要气体。本文对引起口臭的几种病原物质进行了分析，以期为口臭的诊断和治疗提供新的方法。首先，考察了氨监测在评价口臭中的适用性。氨水平与气相色谱法测定的总VSC水平有显著的相关性。氨水平与牙菌斑和舌苔中细菌产生的甲基硫醇水平之间也存在显著相关性。此外，去除舌苔和牙菌斑后，氨水平下降。这些结果表明，测量氨水平对评估口臭是有用的，特别是对缺乏口腔卫生引起的口臭。接下来，从血管链球菌中纯化了从l -半胱氨酸中产生硫化氢的酶。克隆了编码l -半胱氨酸脱氢酶的led基因，对重组蛋白进行了纯化，并对其酶学和生物学特性进行了检测。该l -半胱氨酸脱氢酶具有Michaelis-Menten动力学：K_m = 0.62 mM, V_<max> = 163 μmol min^<-1> mg^<-1>。此外，我们证明了由该酶产生的硫化氢引起绵羊红细胞血红蛋白的修饰和释放。这些结果表明，抑制该酶不仅对减少口腔异味，而且对保护口腔组织免受硫化氢的毒性具有重要意义。

Halitosis originates from microbial putrefaction within the oral cavity, and volatile sulfur compounds (VSCs) are considered the major gases associated with halitosis. In this study, several etiological substances which cause halitosis were examined to develop the new method for the diagnosis and treatment of halitosis.At first, the applicability of ammonia monitoring for assessing halitosis was examined. There was a significant correlation between ammonia level and the total VSC level measured with gas chromatography. Significant correlations were also observed between ammonia level and levels of methyl mercaptan produced by bacteria in dental plaque and tongue coating. Furthermore, the ammonia level decreased after the removal of tongue coating and dental plaque. These results indicate that measuring ammonia levels is useful for assessing halitosis, specifically for halitosis arising from a lack of oral hygiene.Next, the enzyme that produces hydrogen sulfide from L-cysteine was purified from Streptococcus anginosus. The led gene encoding L-cysteine desulfhydrase was cloned, and then the recombinant protein was purified to examine its enzymatic and biological characteristics. This L-cysteine desulfhydrase had the following Michaelis-Menten kinetics: K_m = 0.62 mM and V_<max> = 163 μmol min^<-1> mg^<-1>. In addition, we demonstrated that the hydrogen sulfide produced by this enzyme caused the modification and release of hemoglobin in sheep erythrocytes. These results indicate that the inhibition of this enzyme is important not only for the decrease of oral malodor but also for the protection of oral tissues from the toxicity of hydrogen sulfide.