Estimates of the chromium(VI) reducing capacity in human body compartments as a mechanism for attenuating its potential toxicity and carcinogenicity

Estimates of the overall reducing capacity of hexavalent chromium(VI) in some human body compartments were made by relating the specific reducing activity of body fluids, cell populations or organs to their average volume, number, or weight. Although these data do not have absolute precision or universal applicability, they provide a rationale for predicting and interpreting the health effects of chromium(VI). The available evidence strongly indicates that chromium(VI) reduction in body fluids and long-lived non-target cells is expected to greatly attenuate its potential toxicity and genotoxicity, to imprint a threshold character to the carcinogenesis process, and to restrict the possible targets of its activity. For example, the chromium(VI) sequestering capacity of whole blood (187-234 mg per individual) and the reducing capacity of red blood cells (at least 93-128 mg) explain why this metal is not a systemic toxicant, except at very high doses, and also explain its lack of carcinogenicity at a distance from the portal of entry into the organism. Reduction by fluids in the digestive tract, e.g. by saliva (0.7-2.1 mg/day) and gastric juice (at least 84- 88 mg/day), and sequestration by intestinal bacteria (11-24 mg eliminated daily with feces) account for the poor intestinal absorption of chromium(VI). The chromium(VI) escaping reduction in the digestive tract will be detoxified in the blood of the portal vein system and then in the liver, having an overall reducing capacity of 3300 mg. These processes give reasons for the poor oral toxicity of chromium(VI) and its lack of carcinogenicity when introduced by the oral route or swallowed following reflux from the respiratory tract. In terminal airways chromium(VI) is reduced in the epithelial lining fluid (0.9-1.8 mg) and in pulmonary alveolar macrophages (136 mg). The peripheral lung parenchyma has an overall reducing capacity of 260 mg chromium(VI), with a slightly higher specific activity as compared to the bronchial tree. Therefore, even in the respiratory tract, which is the only consistent target of chromium(VI) carcinogenicity in humans (lung and sinonasal cavities), there are barriers hampering its carcinogenicity. These hurdles could be only overwhelmed under conditions of massive exposure by inhalation, as it occurred in certain work environments prior to the implementation of suitable industrial hygiene measures.      

同种移植排斥反应中T细胞间接识别途径作用的研究

目的　CD+ 4T细胞通过间接识别途径识别MHC Ⅰ类移植抗原而活化已在离体实验中得到证实 ,但体内实验尚未见报道。方法　bml小鼠 (H 2Kbm1∶Kbm1,Db,Ⅰ Ab)的皮肤片分别移植到①B6小鼠 (H 2 b∶Kb,Db,Ⅰ Ab,n =8) ;②B6CD / 8小鼠 (H 2 b∶Kb,Db,Ⅰ Ab,CD / 8,n =8) ;③用抗CD4 抗体处理的B6CD / 8小鼠体上 (n =8)。观察移植皮肤的生长时间 ;用流式细胞仪 (FACScan)观察各组小鼠内T细胞亚群的变化。各组数据用分组或配对t检验进行数据统计。结果　尽管CD / 8小鼠体内未发现CD+ 8T细胞存在 ,但很快排斥了bm1皮肤移植片 (2 1 9d± 1 9d) ;而用抗CD4 抗体处理的B6CD / 8小鼠却长时间接受bm1皮肤移植片 (>47 5d± 3 8d) ;用流式细胞仪发现CD+ 4T细胞明显增殖活化并被抗CD4 抗体抑制。结论　CD+ 4T细胞通过间接识别途径活化并导致同种相异MHC Ⅰ类移植物的排斥。     

生长激素治疗生长激素缺乏症时心脏结构和功能变化

目的评价用人重组生长激素（r－hGH）治疗原发性生长激素缺乏症患者时心脏结构和功能变化。方法对9例确诊为原发性生长激素缺乏患者用r－hGH治疗前后及对20例年龄、性别相匹配的正常青少年通过一维和二维心超检查。结果治疗后患儿的空间隔厚度、左室后壁厚度及心肌重量指数明显上升,与正常相比,仍有一定差异,但差异比治疗前明显缩小。结论生长激素缺乏患者心脏的结构已经受累,但功能尚未有影响,经r-hGH治疗后,心肌重量指数明显上升,提示r-hGH对改善生长激素缺乏患者心脏结构有一定作用。     

Low dose hormone therapy in reproductive endocrinology in China

The human endocrine system normally functions in a balanced physiological state. Any excess or deficiency will cause an endocrine imbalance and result in hyper-or hypo-function, requiring readjustment by hormone suppression or supplementation in order to reestablish a normal physiological balance.     

重症药疹 30 例临床研究

目的：分析重症药疹的临床资料，提供治疗经验。方法：分析我院收治的30例患者，年龄10～71岁，男女比例1．2：1，进行回顾性研究。结果：所有患者均有用药史，常见致敏药物为抗生素、解热镇痛药和卡马西平。死亡率13．3％(4例死亡)，死亡原因主要是心肺衰竭和感染。患者本身的基础性疾病是引起死亡的主要危险因素，包括布．力口综合征、肺结核、支气管哮喘和系统性红斑狼疮。结论：早期诊断和停用致敏药物是治疗的重要环节，激素治疗能明显控制症状和缓解病情，支持疗法和皮肤黏膜护理也发挥重要作用。     

螺旋CT成像后处理在腰椎峡部裂中的应用

目的 探讨螺旋CT成像后处理在腰椎峡部裂诊断中的临床价值。方法 分析20例腰椎峡部裂最大密度投影(MIP)、多平面重组(MPR)、表面重建(SSD)重建图像的CT表现。结果MIP和MPR显示峡部裂艮好，20例38处均能显示，前者更清晰；SSD图像显示椎体滑脱良好，16例椎体滑脱均能显示；峡部断裂断端骨赘形成7例，纤维组织增生或骨痂形成6例，侧隐窝狭窄6例，黄韧带肥厚3例，椎间盘突出5例，椎间孔狭窄12例，斜轴位或矢状位MPR均能很好显示。结论 “断翼征”、“断柄征”，“断颈征”、“环裂征”是腰椎峡部裂特征性的CT表现，螺旋CT的多系列重建图像对峡部裂的诊断以及治疗方式的选择具有重要意义。     

临床分离耐喹诺酮阴沟肠杆菌gyrA基因突变的研究

目的：检测临床分离耐喹诺酮阴沟肠杆菌DNA促旋酶gyrA基因突变情况。方法：收集临床分离耐喹诺酮阴沟肠杆菌30株及敏感株10株，测定其对萘啶酸、环丙沙星、氧氟沙星的最低抑菌浓度(MIC)；用聚合酶链反应(PCR)扩增gyrA基因部分片断，对PCR产物进行限制性片断长度多态性(PCR—RFLP)及单链构象多态性(PCR—SSCP)分析，检测gyrA突变情况。结果：30株耐喹诺酮菌株都检测到gyrA基因突变，PCR—RFLP均显示两条不同于敏感株的电泳带，其PCR—SSCP则检测到4种不同于敏感菌的迁徙率条带；而10株敏感菌均未检测到gyrA基因突变。结论：阴沟肠杆菌对喹诺酮类药物耐药性与gyrA基因突变有关，gyrA基因第83位氨基酸密码子突变可能为其耐药的主要原因。     

Dynamic computed tomography of the head and neck: differential diagnostic value

A retrospective review of the dynamic CT studies performed in our institution on head and neck lesions, excluding the brain, was carried out. Five basic types of density vs. time curves were obtained. Dynamic CT scanning is valuable in the differential diagnosis, management, and followup of such cases; its usefulness as an imaging modality in diagnosis and followup of hemangiomas is stressed.     

2型糖尿病合并高血压对血脂代谢的影响

目的观察2型糖尿病患者合并高血压对血脂代谢的影响。方法2型糖尿病正常血压组47例与合并高血压组127例,检测空腹血浆葡萄糖、血脂代谢指标。结果正常血压组和合并高血压组,血清三酰甘油、总胆固醇、低密度脂蛋白胆固醇水平的差异有显著意义。将二组患者按性别、年龄分组后,合并高血压组<60岁男性患者的三酰甘油不仅高于≥60岁男性患者,而且高于<60岁组女性患者;<60岁组男性患者的总胆固醇与高密度脂蛋白胆固醇比值高于≥60岁男性患者组,差异有显著意义。<60岁女性患者载脂蛋白B100值高于≥60岁组;载脂蛋白A-I与载脂蛋白B100的比值低于≥60岁组,差异有显著意义。在合并高血压组,空腹血浆葡萄糖、脂蛋白(a)、总胆固醇与高密度脂蛋白胆固醇的比值与平均动脉压呈正相关关系。糖尿病合并高血压后,血脂异常的类型仍以高三酰甘油血症为主,但高胆固醇血症及混合型高脂血症的比率发生变化。结论当2型糖尿病合并高血压时,加重了血脂异常;年龄、性别因素对血脂代谢亦有影响,且血脂异常类型单纯糖尿病和糖尿病伴高血压不同。     

6,8-二甲基-5,7,4′-三羟基双氢黄酮合成的研究

6,8-二甲基-5,7,4′-三羟基双氢黄酮(Ⅴ,简称Farrerol)是从黑龙江省植物满山红(Rhododendron dauricum L.)叶中分离出的化痰有效成分之一。本文报道两种合成farrerol的方法:A法自2,4,6-三羟基-3,5-二甲基苯(Ⅰ)与对-乙氧羰基香豆酸酰氯(Ⅳ)进行Fries重排;环合反应,B法为化合物Ⅰ经2,4,6-三羟基-3,5-二甲基苯乙酮(ⅪⅤ)与对-羟基苯甲醛(Ⅻ)在乙二醇,硼酸中进行缩合。合成品farrerol为消旋体,与天然品的药理作用、毒性及临床效果一致。