Carrier mediated transport of choline in rat lens

Choline accumulation was studied in rat lenses incubated in TC-199 medium containing radiolabeled choline. Choline entered the lens and was rapidly phosphorylated. Phosphorylcholine did not readily escape the lens and continued to accumulate throughout 24 hr of incubation. Accumulation of choline displayed saturation kinetics and this saturability appeared to be a property of transport rather than a reflection of the properties of choline kinase. Countertransport of labeled choline from lenses preloaded with radiolabeled choline indicates that choline transport in rat lens is carrier mediated. The existence of a choline carrier would also be consistent with the kinetic data. Ethanolamine competed for the choline carrier, however a component of ethanolamine uptake was non-saturable at concentrations of ethanolamine or choline up to 5 mm. Choline and ethanolamine appeared to be phosphorylated by separate kinases in lens.     

Studies on corneal penetration ofp-hydroxybenzoic acid esters

Corneal permeability of variousn-alkylp-hydroxybenzoates (parabens) was studiedin vitro using excised rabbit corneas, and the effect of lipophilicity of parabens on the corneal permeability was also investigated. Permeability coefficients were obtained from the least-square linear regression after the steady state had been reached. Lipophilicity of parabens was calculated by distribution coefficients determined in octanol-S \(12_\phi [\kern-0.15em[ \) rensen’s buffer solution (pH 5.0). The relationship between lipophilicity and corneal permeability of parabens was not linear, but the optimum lipophilicity for the maximum permeation was found. The influence of tween 80 on corneal permeability of methyl and butylparaben was not significant.     

Light-dependent delay in the falling phase of the retinal rod photoresponse.

Using suction electrodes, photocurrent responses to 100-ms saturating flashes were recorded from isolated retinal rods of the larval-stage tiger salamander (Ambystoma tigrinum). The delay period (Tc) that preceded recovery of the dark current by a criterion amount (3 pA) was analyzed in relation to the flash intensity (If), and to the corresponding fractional bleach (R*0/Rtot) of the visual pigment; R*0/Rtot was compared with R*s/Rtot, the fractional bleach at which the peak level of activated transducin approaches saturation. Over an approximately 8 ln unit range of I(f) that included the predicted value of R*s/Rtot, Tc increased linearly with ln I(f). Within the linear range, the slope of the function yielded an apparent exponential time constant (tau c) of 1.7 +/- 0.2 s (mean +/- S.D.). Background light reduced the value of Tc measured at a given flash intensity but preserved a range over which Tc increased linearly with ln I(f); the linear-range slope was similar to that measured in the absence of background light. The intensity dependence of Tc resembles that of a delay (Td) seen in light-scattering experiments on bovine retinas, which describes the period of essentially complete activation of transducin following a bright flash; the slope of the function relating Td and ln flash intensity is thought to reflect the lifetime of photoactivated visual pigment (R*) (Pepperberg et al., 1988; Kahlert et al., 1990). The present data suggest that the electrophysiological delay has a similar basis in the deactivation kinetics of R*, and that tau c represents TR*, the lifetime of R* in the phototransduction process. The results furthermore suggest a preservation of the "dark-adapted" value of TR* within the investigated range of background intensity.     

毛冬青甲素体外给药对花生四烯酸诱导的兔血小板聚集和丙二醛生成的影响

研究了毛冬青甲素体外给药对花生四烯酸诱导兔血小板聚集和聚集液中过氧化脂质含量变化的影响。结果表明,毛冬青甲素在较大样本中可抑制花生四烯酸诱导的血小板聚集和过氧化脂质的生成,两者间具有一定的相关性,表明毛冬青甲素抗血小板作用可能与抑制过氧化脂质有关。由于后者的生成量与花生四烯酸代谢活性产物TxA₂的生成有近似等摩尔增加的关系,故推测毛冬青甲素对TXA₂的合成有阻断作用,这种作用可能为毛冬青甲素抗血小板功能的作用机制。     

颈内动脉—后交通动脉瘤的外科治疗：附13例报告

我院自1982年～1988年共收治13例颈内动脉-后交通动脉瘤。本文就该处动脉瘤的临床诊断、手术入路以及动脉瘤破裂的预防和处理进行了讨论。     

血栓素B2的高效液相荧光测定及刺五加提取物的抗血小板作用

本文在Turk及Wintersteiger荧光衍生实验的基础上,建立了反相HPLC法测定血小板TXB₂含量的方法.血小板TXB₂用Sep-PakC₁₈提取,在冠醚和碳酸钾存在下,BrMmc与TXB₂的羧基反应生成BrMmc-TXB₂。然后经Zorbax-ODS柱(250mm×4.6mm,5μm)分离,测定荧光强度(E×345,Em405)。流动相为乙腈:水:磷酸(60:40:0.1V/V),流速1ml/min.BrMmc-TXB₂的分离在20min内完成。TXB₂的含量用外标法定量,检测限15ng。体外实验刺五加提取物(0.275～2.2mg/mlPRP)对AA、ADP诱导的家兔血小板聚集有明显的抑制作用,并能抑制AA诱导的血小板TXB₂的生成。静脉注射(120mg/kg)对AA、ADP诱导的聚集也有抑制作用。     

Histoclinical Analysis of Early Colorectal Cancer

To evaluate the clinicopathologic characteristics of early colorectal cancer (ECC), histopathologic and clinical features of 90 ECC patients who underwent surgical resection (not including the endoscopic polypectomized cases) and 1704 patients with advanced colorectal cancer were analyzed. Smaller size, better histologic differentiation, less lymph node (LN) metastasis, and better clinical outcome were observed in those with ECC than in patients with more advanced lesions. LN metastasis was found in 5 patients with ECC among the 56 patients who underwent bowel resection (8.9%). Tumors with LN metastasis were more frequently associated with deep submucosal invasion, absence of an adenomatous component within the tumor, sessile configuration, and lymphovascular invasion. Tumors showing deep submucosal layer invasion were associated with a more unfavorable histologic grade, lymphovascular invasion, LN metastasis, sessile morphology, and absence of an adenomatous component within the tumor. Recurrence was observed in two patients who underwent local excision for their submucosal cancer. One of the patients was salvaged after bowel resection, but one patient died of distant metastasis. From our data analysis and literature review, extensive submucosal invasion, lymphovascular invasion, sessile configuration, and tumors with no adenomatous component should be considered high risk factors for LN metastasis and recurrence after limited therapy.     

落液林治疗慢性肺源性心脏病的疗效观察及机制探讨

目的　观察落液林对慢性肺源性心脏病的临床疗效并探讨其机制。方法　选择 10 8例慢性肺源性心脏病患者 ,随机分成两组 ,试验前评价心功能及监测动脉血气、右房压 (RAP)、右室压 (RVP)、平均肺动脉压 (m PAP)、全血高切黏度、全血低切黏度、血浆黏度、红细胞压积、纤维蛋白原、血红蛋白定量和红细胞计数等指标。对照组只给予常规治疗 ,落液林组在给予常规治疗的同时合并给予落液林 30 0 m g/ d,稀释后静脉滴注 ,疗程 3周 ;3周后 ,复查上述指标 ,比较各组前后的变化。结果　落液林组心力衰竭纠正有效率为 79.6 3% ,显著高于对照组 (P<0 .0 5 ) ;试验前后比较落液林组血氧分压 (pO2 )显著上升 ,血二氧化碳分压 (pCO2 )显著下降 ;而对照组均无显著性变化 ;落液林组 RAP、RVP、m PAP均明显下降 ;而对照组无显著性变化 ;落液林组全血高切黏度、全血低切黏度、血浆黏度、红细胞压积、纤维蛋白原、血红蛋白定量和红细胞计数等指标均明显下降 ;而对照组则无显著变化。结论　落液林对慢性肺源性心脏病具有纠正心力衰竭、降低肺动脉及右心房和右心室压力、改善血液流变和动脉血气的作用。