人正常下颌升支区应力分布的三维有限元法分析

目的：对正常人下颌升支在不同咀嚼力作用时应力分布情况进行三维有限元分析。方法：采用三维有限元应力分析的方法，对正常离体人下颌升支在不同加载条件下的应力分布特征进行对比定量分析。结果：(1)所有载荷形式的各种应力值，随着单元距加载点的距离的增大，其应力值相对减小。(2)下颌骨下颌角、升支后缘的应力梯度变化较大。结论：下颌骨下颌角、升支后缘是应力相对集中的区域，也是临床上常见的下颌骨骨折区，同时还是下颌升支矢状骨劈开术后加强固定以及防止骨段移位的区域。     

肺栓塞1例

[背景 ]对肺栓塞的认识普遍较低 ,容易漏诊、误诊 .[病例报告 ]患者年龄为 5 7岁 ,女性 ,以原因不明的呼吸困难为主要症状 ,超声心动图检查示右心房右心室扩大及肺动脉高压 .进一步做CT肺血管造影检查确诊为肺栓塞 .[讨论 ]可根据临床表现及非特异性检查 (胸部X线片、超声波及心电图等检查 )确诊肺栓塞 ,当疑似为肺栓塞时可做有确诊意义的CT肺血管造影检查 .     

丝裂霉素C在复发性青光眼中的应用

目的 :观察丝裂霉素C(MMC)在抗青光眼手术中应用的近期及远期效果。方法 :4 2只复发性青光眼在二次手术中一次性应用MMC术后观察及随访。结果 :术前眼压 34.0 5± 4 .0 5mmHg ,明显高于随访半年期 13.13± 3.30mmHg以及随访 2年期 14 .33± 3.30mmHg ,差异有显著性 (P <0 .0 1)。术后近期眼压 6 .75± 1.4 3mmHg ,明显低于随访半年期 (P <0 .0 1)。功能性滤过泡所占比率为 95 .2 %。结论 :术中一次性应用MMC ,远期观察其降压效果明显 ,且无严重并发症发生     

Tamoxifen induces ultrastructural alterations in membranes of Bacillus Stearothermophilus

Tamoxifen (TAM), a non-steroid antiestrogen, is the mostly used drug for chemotherapy and chemoprevention of breast cancer. However, the mechanisms by which TAM inhibits cell proliferation in breast cancer are not fully understood. TAM strongly incorporates in biomembranes and a variety of effects have been assigned to biophysical and biochemical interactions with membranes. Therefore, a better understanding of the physicochemical basis of interaction of TAM with biomembranes is essential to elucidate the molecular mechanisms of action. A strain of Bacillus stearothermophilus has been used as a model to clarify the interaction of TAM with the cell membrane. TAM effects on the ultrastructure of membranes of this bacterium were evaluated by electron microscopy. Important ultrastructural alterations were observed in B. stearothermophilus treated with TAM, namely change in the geometry of the membrane profile from asymmetric to symmetric, disaggregation of ribosomes, coagulation of the cytoplasmic matrix, occurrence of mesossomes, appearance of fractures in membranes and the alteration of the ultrastructure of cell wall. These ultrastructural alterations confirm that TAM is a membrane-active drug and that membrane damage may be involved in molecular mechanisms of cell death induced by this drug.     

Tamoxifen induces ultrastructural alterations in membranes of Bacillus Stearothermophilus.

Tamoxifen (TAM), a non-steroid antiestrogen, is the mostly used drug for chemotherapy and chemoprevention of breast cancer. However, the mechanisms by which TAM inhibits cell proliferation in breast cancer are not fully understood. TAM strongly incorporates in biomembranes and a variety of effects have been assigned to biophysical and biochemical interactions with membranes. Therefore, a better understanding of the physicochemical basis of interaction of TAM with biomembranes is essential to elucidate the molecular mechanisms of action. A strain of Bacillus stearothermophilus has been used as a model to clarify the interaction of TAM with the cell membrane. TAM effects on the ultrastructure of membranes of this bacterium were evaluated by electron microscopy. Important ultrastructural alterations were observed in B. stearothermophilus treated with TAM, namely change in the geometry of the membrane profile from asymmetric to symmetric, disaggregation of ribosomes, coagulation of the cytoplasmic matrix, occurrence of mesossomes, appearance of fractures in membranes and the alteration of the ultrastructure of cell wall. These ultrastructural alterations confirm that TAM is a membrane-active drug and that membrane damage may be involved in molecular mechanisms of cell death induced by this drug.     

Mercury from gold minings in the Pantanal of Pocone (Mato Grosso,Brazil)

The Pocone gold minings are situated in the Bento Gomes River Basin, at the border of the Pantanal of Mato Grosso. Gold-bearing quartz veins are removed from the subsoils, milled with water, centrifuged and the heavier fraction is subsequently mixed with mercury for gold separation. The gold mining activities caused a very intensive landscape change, threatening many environmental processes like sediment control and storage and recycling capacity of mercury. Cold Vapor Atomic Fluorescence System (CVAFS) was used to determinate total mercury in water, suspended material and sediments from Bento Gomes River, sampled monthly for 1 year. Apart from the fact that mercury concentrations are low in water and bottom sediments, they are slightly higher in relation to background levels measured in the area. The concentration in suspended material is also lower than other rivers with gold mining activities, but the floodplains of the Bento Gomes River act as mercury sinks. Therefore, the discharge of mercury into the Pantanal floodplain should be avoided, in spite of actual contamination of the system being very low.     

Toxicity of prolonged exposure to ethanol and gasoline autoengine exhaust gases

A comparative chronic inhalation exposure study was performed to investigate the potential health effects of gasoline and ethanol engine exhaust fumes. Test atmospheres of gasoline and ethanol exhaust were given to Wistar rats and Balb C mice housed in inhalation chambers for a period of 5 weeks. Gas concentration and physical parameters were continually monitored during the exposure period. Several biological parameters were assessed after the exposure including pulmonary function, mutagenicity, and hematological, biochemical, and morphological examinations. The results demonstrated that the chronic toxicity of the gasoline-fueled engine is significantly higher than that of the ethanol engine.     

Immunophenotypic analysis of human spleen compartments.

Microanatomical compartments of the human spleen are yet under evaluation as most of the present information comes from experiments on animals with different anatomical structures. Immune staining of stromal and blood-born cells by cell surface antigens facilitates the differentiation of functional microanatomical compartmentalization of immune organs, including the spleen. Twenty-two specimens from healthy adult subjects with the average age of 35.6 +/- 13.8 (Range 17 to 58) years were included in this study. Monoclonal antibodies used in this study were supplied from the 5th, 6th and 7th International Workshops and Conferences on Human Leukocyte Differentiation Antigens. Tetraspan antigens presented a rather unique staining pattern in the human spleen, suggesting special roles for each (CD9, CD53, CD63, CD151 and CD231) in certain locations. Sinus lining cells presented a distinctive antigenic profile, sharing both endothelial cell (CD31, CD36, CD54, CD62P, CD102, CD105, CD106 and CD146) and macrophage lineage characteristics. The sheathed capillaries were not restricted to the perifollicular zone alone. Extracellular matrix receptors (CD49 a, CD49 b, CD49 c, CD49 e, CD49f, CD29 and CD44) stained the penicillary arterioles and vascular smooth muscle. These molecules were also found on the vascular endothelium. Leukocyte antigens (CD11a, CD11b, CD22, CD43, CD45, CD45RB, CD45RO and CD50) were mainly expressed in the white and red pulp of the spleen at different intensities, excluding the penicillary arterioles. Activation antigens (CD26, CD71 and CD98) presented a diffuse and broad staining pattern. In conclusion, microanatomical compartmentalization, microcirculation and function of the human spleen were evaluated using a wide panel of monoclonal antibodies.     

Functional uncoupling of hemodynamic from neuronal response by inhibition of neuronal nitric oxide synthase.

The cerebrovascular coupling under neuronal nitric oxide synthase (nNOS) inhibition was investigated in alpha-chloralose anesthetized rats. Cerebral blood flow (CBF), cerebral blood volume (CBV), and blood oxygenation level dependent (BOLD) responses to electrical stimulation of the forepaw were measured before and after an intraperitoneal bolus of 7-nitroindazole (7-NI), an in vivo inhibitor of the neuronal isoform of nitric oxide synthase. Neuronal activity was measured by recording somatosensory-evoked potentials (SEPs) via intracranial electrodes. 7-Nitroindazole produced a significant attenuation of the activation-elicited CBF (P<10(-6)), CBV (P<10(-6)), and BOLD responses (P<10(-6)), without affecting the baseline perfusion level. The average DeltaCBF was nulled, while DeltaBOLD and DeltaCBV decreased to approximately 30% of their respective amplitudes before 7-NI administration. The average SEP amplitude decreased (P<10(-5)) to approximately 60% of its pretreatment value. These data describe a pharmacologically induced uncoupling between neuronal and hemodynamic responses to functional activation, and provide further support for the critical role of neuronally produced NO in the cerebrovascular coupling.     

Tibial hemimelia: report on 37 new cases, clinical and genetic considerations

We report on 37 patients belonging to different families, who have the tibial hemimelia-split hand/foot syndrome. Genetic aspects and phenotypic manifestations are compared with previous reports of tibial hemimelia. An attempt to clinical and genetical approach is suggested.