LCMS Grade Acetonitrile Product Description
CovaChem's LCMS Grade Acetonile is a high purity solvent (> 99.9%), ideally suited for LC/MS and other mass spectrometry related applications. CovaChem's LCMS Grade Acetonitrile is submicron filtered, has very low levels of trace metals, and each lot is functionally tested for optimal baseline suitability in both positive and negative ionization modes.
Package Sizes: 1 Liter, 4 Liters and 4 x 4 LitersProduct Numbers: 17412-1, 17412-4, 17412-4x4
Product Name: LCMS Grade Acetonitrile
Alternative Names: LCMS Acetonitrile; LC/MS Grade Acetonitrile; LCMS Methyl cyanide; Acetonitrile for LC/MS
Specifications
Appearance: Clear, Colorless Liquid
Purity (GC): ≥ 99.9 %
Trace Metal Analysis: To pass test
LC Gradient Stability Test (254 nm): To pass test
Residue after evaporation: 1 mg/L max
Water: 0.010 % max
UV Cutoff: 190 nm
Fluorescence at Emission max (impurity test): 1 ppb Max
LC/MS Positive Ion Mode (as Reserpine): 50 ppb Max
LC/MS Negative Ion Mode (as Nitrophenol): 50 ppb Max
Recommended Storage: Room Temperature, protected from excess light
Properties
Properties Physical State: Liquid
Melting Point: - 48 °C (lit.)
Boiling Point: 81 - 82 °C at 760 mmHg (lit.)
CAS#: 75-05-8
Chemical Formula: C2H3N
Molecular Weight: 41.05
Country of Origin: USA
Tariff Code: 2926.90.5050
UN Transportation Code: 1648
Important Notes:
(1) $ 25 Hazardous transportation charge for domestic shipments is INCLUDED in the price listed online.
(2) Due to the weight and hazards associated with this product, not all shipping options are available for this product. After receipt of order, a customer service representative may contact you to modify shipping option.
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多肽和蛋白质类激素(不可口服):促甲状腺激素释放激素,促甲状腺激素,促性腺激素、生长激素,催乳素,胰岛素,胰高血糖素,
氨基酸类衍生物(可口服):甲状腺激素、肾上腺素
脂质类激素:(可口服)性激素和孕激素
蛋白质类激素不能口服,因会被消化液中的蛋白酶分解(——这是原因)
这是我们老师说的哦!!希望对你有帮助
作者、斯坦福大学医学中心的梅斯勒(AnnaH.Messner)和同事解释,有多个研究曾检查了在扁桃体切除手术前使用类固醇类药的情况,但得到的结果不一。据他们在8月《耳鼻喉、头、颈外科文献》(ArchOtolaryngolHeadNeckSurg2004;130:917-921)上发表的论文说,他们对这种病人进行了一项最大的前瞻性、随机、双盲研究。
共219名9个月至12岁的参试者被随机分为或用地塞米松1mg/kg,最大剂量至50mg(n=106),或用安慰剂(n=113)。在药物组中,62人进行的扁桃体切除术采用的是电烧烙法,44人采用的是锐性分离。安慰剂两种方法分别为56人和57人。术后第一天,类固醇组医生评定的Wong-Baker可视模拟量表上的疼痛分平均为4.4,安慰剂组5.3(p<0.001);前组家长评估的疼痛分(p=0.002)和病儿自己评估的疼痛分((p=0.002))也明显更低。类固醇组有1.2次呕吐发作,安慰剂组2.1次(p=0.02),前组也更快地恢复了正常进食(=0.004)。另外,作者还发现,进行锐性分离的病人使用类固醇受益最大,医生和家长评估的疼痛分显著低于电烧烙组。
“我们的研究结果支持在进行扁桃体手术时以1mg/kg的剂量IV地塞米松”,研究者总结。
http://care.diabetesjournals.org/cgi/content/abstract/31/8/1479
OBJECTIVE—Hyperglycemiaisariskfactorformicrovascularcomplicationsandmayincreasetheriskofcardiovasculardiseaseinpatientswithtype2diabetes.ThisstudytestedtheLDLcholesterol–loweringagentcolesevelamHCl(colesevelam)asapotentialnoveltreatmentforimprovingglycemiccontrolinpatientswithtype2diabetesonsulfonylurea-basedtherapy.
RESEARCHDESIGNANDMETHODS—A26-week,randomized,double-blind,placebo-controlled,parallel-group,multicenterstudywascarriedoutbetweenAugust2004andAugust2006toevaluatetheefficacyandsafetyofcolesevelamforreducingA1Cinadultswithtype2diabeteswhoseglycemiccontrolwasinadequate(A1C7.5–9.5%)withexistingsulfonylureamonotherapyorsulfonylureaincombinationwithadditionaloralanti-diabetesagents.Intotal,461patientswererandomized(230givencolesevelam3.75g/dayand231givenplacebo).Theprimaryefficacymeasurementwasmeanplacebo-correctedchangeinA1Cfrombaselinetoweek26intheintent-to-treatpopulation(lastobservationcarriedforward).
RESULTS—Theleastsquares(LS)meanchangeinA1Cfrombaselinetoweek26was–0.32%inthecolesevelamgroupand+0.23%intheplacebogroup,resultinginatreatmentdifferenceof–0.54%(P<0.001).TheLSmeanpercentchangeinLDLcholesterolfrombaselinetoweek26was–16.1%inthecolesevelamgroupand+0.6%intheplacebogroup,resultinginatreatmentdifferenceof–16.7%(P<0.001).FurThermore,significantreductionsinfastingplasmaglucose,fructosamine,totalcholesterol,non–HDLcholesterol,andapolipoproteinBweredemonstratedinthecolesevelamrelativetoplacebogroupatweek26.
CONCLUSIONS—ColesevelamimprovedglycemiccontrolandreducedLDLcholesterollevelsinpatientswithtype2diabetesreceivingsulfonylurea-basedtherapy.
为了帮助临床医师客观地了解NSAIDs,避开制药公司的导向以便更好地指导临床实践,本报请广州中山大学附属第一医院风湿免疫内科杨岫岩教授向读者介绍NSAIDs临床应用的一些问题。
NSAIDs的发展
从乙酰水杨酸(阿司匹林)应用至临床到现在,已经超过100个年头。1948年第一个非水杨酸类的NSAIDs保泰松问世后,抗炎镇痛药的种类迅速增加,如吲哚美辛、双氯芬酸、布洛芬、萘普生等,使NSAIDs“家族”迅速壮大。作为其“元老”的保泰松,虽然具有很强的抗炎镇痛作用,但潜在的严重副作用(再生障碍性贫血等)使其被淘汰。
1971年,环氧化酶(COX)理论解释了NSAIDs的作用机制。NSAIDs通过抑制COX,阻止花生四烯酸转变为前列腺素,后者既是炎症介质,又有生理功能。因此NSAIDs在抗炎镇痛的同时可引起胃肠道反应。20年后,研究者发现,COX存在不同的异构体,从而提出了COX异构体理论。认为COX存在两个异构体,一个是构建型的,称COX-1,以维持生理平衡为主;另一个是诱导型的称COX-2,主要参与炎症性前列腺素合成。
1994年,氟舒胺成为第一个被报道在实验室证实具有选择性COX-2抑制作用的NSAIDs,但在1996年III期临床试验总结时发现,该药具有肝毒性而未能获准上市。1995年Lancet上首先称萘丁美酮、美洛昔康、尼美舒利等为“选择性COX-2抑制剂”,虽然同年该期刊刊出几篇读者来信,对此提法提出争议,但是后来人们仍普遍接受这种提法。1999年,针对COX异构体理论研制的昔布类药物(塞来昔布和罗非昔布)上市,被称为“特异性COX-2抑制剂”。
虽然COX异构体理论尚需完善,但它的确是新型NSAIDs研制的一个突破口。除已经问世的昔布类药物外,新的昔布类Etoricoxib、parecoxib、valdecoxib也将投入临床。新研制的COX-2抑制剂不只限于昔布类,磺酰苯胺类也是研制新型COX-2抑制剂的方向,如氟舒胺、NS-398、HN-56249等。另外,针对COX和脂氧化酶(5-lipoxygenase
B、是重要的储能物质,磷脂为构成生物膜的重要成分,固醇为动物细胞膜的构成物质及形成激素等,B错误;
C、蛋白质是细胞代谢的主要结构物质,糖类是细胞代谢的主要能源物质C错误;
D、ATP的结构简式是 A-P~P~P,其中A代表腺苷,腺苷是构成ATP的重要部分,D正确.
故选:D.

