Polyamines in Trichomonas vaginalis

Trichomonas vaginalis was grown in a modified Bushby's medium and putrescine, spermidine and spermine levels were determined in extracts from 24- and 48-h cultures and also in the culture media. All three polyamines were present in T. vaginalis extracts; the putrescine level and putrescine/spermidine ratio were much higher than those reported for other protozoa or for mammalian tissues. There were no significant differences between 24-h and 48-h amine levels per mg protein in these extracts, but amine levels per cell were higher at 24 than at 48 h. The spent culture media had a much higher putrescine content than corresponding uninoculated media and it was concluded that T. vaginalis secreted putrescine into the culture medium.     

Intracellular calcium ions activate a low-conductance chloride channel in smooth-muscle cells isolated from human mesenteric artery

Calcium-activated chloride currents were studied by the patch-clamp technique in vascular smooth muscle cells (VSMC) isolated from human mesenteric arteries. Bath application of 20 mM caffeine caused the cell membrane to depolarize by a calcium-activated inward current that peaked to –654±230 pA (holding potential –50 mV). Cell-attached, at the same time inwardly directed single-channel currents were detected with an amplitude of –0.22 pA. In open-cell-attached patches channel activity was triggered by elevating [Ca²⁺]_i to 10 M. At –60 mV the mean amplitude of the current was –0.24 pA and the mean open time of the channels was 28 ms. Plotting the amplitude of the current versus the test potential yielded a single-channel conductance of 2.8±0.5 pS. The currents disappeared when [Cl^–] was reduced from 150 mM to 5 mM at the cytosolic side of the inside-out patch at a holding potential of -60 mV (calculated reversal potential –58 mV) suggesting that the calcium-activated current was a chloride current. This suggests that, in human mesenteric VSMC, elevation of [Ca²⁺]_i activates a low-conductance chloride channel, which may mediate the agonist-induced depolarization of the cell membrane.     

Two cases of liver angiosarcoma among polyvinyl chloride (PVC) extruders of an Italian factory producing PVC bags and other containers

Two cases are reported of liver angiosarcoma occurring among polyvinyl chloride (PVC) extruders from a small Italian factory producing PVC bags and other containers. The possibility that PVC extrusion carries a risk of liver angiosarcoma is important because of the very large number of people working with extruding, manufacturing and handling PVC, as compared with the number of people working in PVC polymerization and/or VC production. In the past, the level of vinyl chloride (VC) concentration in PVC extrusion workplaces has been thought to be "safe".     

Influence of exposure mode on vinyl chloride action

Rats were subjected to 4 h continuous or intermittent exposure to vinyl chloride (VC) at different time-weighted average concentrations (15, 50, 150, 500 and 15,000 mg/m³). Hepatic non-protein sulfhydryl content (NPSH) and excretion of thiodiglycolic acid (TdGA) in urine were determined. VC at concentrations from 50 mg/m³ to 15,000 mg/m³ caused a dose-dependent depression of NPSH, but no difference in the magnitude of this depression induced by continuous or intermittent exposure at the same average concentration of VC was noted. At average concentrations of 50 mg/m³ and 150 mg/m³, the urinary excretion of TdGA under continuous exposure did not differ from that under intermittent exposure, whereas at VC concentrations of 500 mg/m³ and 15,000 mg/m³ it was higher following continuous exposure.     

氯化铁催化合成苯甲酸异戊酯的研究

本文研究了用氯化铁 (FeCl3·6H2 O)催化苯甲酸和异戊醇的酯化反应 ,当苯甲酸∶异戊醇 =1∶3(摩尔比 ) ,氯化铁用量 1.0g/0 .1mol苯甲酸 ,回流分水 2 .5h时 ,酯化率 90 .3 %。     

聚硅氯化铁的制备及其混凝效果

以硅酸钠、氯化铁为原料制备聚硅氯化铁（简称ＰＦＳＣ）混凝剂。重点考察Ｆe/SiO2摩尔比对ＰＦＳＣ混凝效果的影响。结果表明：ＰＦＳＣ的混凝效果优于聚硅酸（ＰＳ）,且Ｆe/SiO2摩尔比对ＰＦＳＣ的混凝效果有较大的影响。确定Ｆe/SiO2摩尔比为１：１.５时,其混凝效果最佳,且用药量少而范围广。为制备高效的ＰＦＳＣ提供了优化条件。     

氯化钛白氧化反应器壁结疤机理

利用预燃烧直管反应器,研究氯化钛白氧化反应器内的结疤机理。氧化反应器内结疤支要起因子氧化过程生成的超细TiO2颗粒在反应器壁的沉积和烧结,反应器壁面温度越高结疤速率越快。当反应器壁面温度较低时,靠近壁面为ＴiO2颗粒堆结层,而告气体相主体的疤层发生了部分烧结。反应温度升高、反应物浓度增大时,结疤速度增大;壁面状态对结疤速率影响不大。     

一氧化氮对犬下食管括约肌压力的作用

目的 :应用苄基二甲基十四烷氯化铵 (benzyldim ethyltetradecyl amm onium chloride,BAC)建立犬下食管括约肌(L ES)无神经动物模型 ,研究一氧化氮 (NO)对 L ES压力的作用。方法 :将 BAC环周注入犬 L ES,对照组注入等量生理盐水 ,均于注射前及注射后 6周测定 L ES压力 ;并观察 L -精氨酸、D -精氨酸、硝普钠及一氧化氮合酶 (NOS)抑制剂 N-硝基 - L -精氨酸 (L - NNA)对 L ES压力的影响 ;此外还测定了两组犬 L ES中 NO含量和 NOS活性。结果 :BAC处理组 L ES压力 [(4 2 .43±4.19) m m Hg,1m m Hg=0 .133 k Pa]显著高于对照组 [(2 2 .71± 5 .19) mm Hg]。 L -精氨酸可使对照组 L ES压力降低 ;L - NNA使其增高 ,但对 BAC处理组 L ES压力均无影响。硝普钠可降低两组犬 L ES压力。对照组 L ES中 NO为 (6 .0 5 8± 2 .0 6 7)μm ol/g,NOS为 (1.45 8± 0 .146 ) U /mg;而 BAC处理组 NO为 (1.797± 0 .873)μmol/g,NOS为 (0 .46 3± 0 .0 39) U /m g,均较对照组显著降低 (P<0 .0 1)。 结论 :BAC可使犬 L ES压力增高 ,其机制可能与 L ES局部 NO减少有关。     

Is a Titanium Implant for Total Knee Arthroplasty Better? A Randomized Controlled Study

BackgroundLighter weight and lower modulus are potential advantages of titanium (Ti) implants over cobalt chrome (CoCr) implants in total knee arthroplasty (TKA). This study was conducted to determine whether Ti implants in TKA resulted in better clinical outcomes and radiologic results.MethodsOne hundred and eight patients (216 knees) with knee arthritis warranting bilateral primary TKA were randomly allocated to undergo Ti rotating-platform TKA in one knee and CoCr rotating-platform TKA in the contralateral knee. The mean follow-up period was 5.3 years (range, 1-7 years). The weight of Ti implants was one-third lighter than that of CoCr implants (133.9 g vs 390.1 g, P < .01). Clinical outcomes were evaluated using clinical scores, patient preferences (lightness, comfort, naturalness, and satisfaction), gait analysis (kinetic and kinematic data), range of motion, and degree of pain. Radiologic results were evaluated based on the radiolucent line (RLL), degree of medial tibial bone loss, and loosening as seen on X-ray.ResultsNo significant differences were observed in clinical scores or patient preference. Regarding implant weight, approximately 70% of patients did not perceive the Ti implant as lighter. No significant differences were observed in gait analysis, range of motion, or degree of pain. The RLL was seen in 9% of the Ti implant group and 19% of the CoCr implant group.ConclusionThe lighter Ti implant did not show any clinical benefit over CoCr implants. The lightness of the Ti implant is not sufficient to matter or be noticeable. However, the Ti implant showed lower rate of RLL than the CoCr implant.Level of Evidencelevel I, randomized controlled trial.