蒿甲醚诱发日本血吸虫脂质过氧化

目的　观察蒿甲醚 (Art)对日本血吸虫的脂质过氧化损伤。方法　小鼠感染血吸虫尾蚴 5周后 ,1次灌服Art30 0mg/kg ,于治疗后 6～ 2 4h剖杀 ,收集雄虫 ,用硫代巴比妥酸 (TBA)比色方法测定其TBA反应物 (TBARs)水平。并取未经药物治疗的合抱虫 ,置于含Art和 /或氯化血红素 (hemin)的培养液内培养 2 4h后 ,作TBARs分析。结果　小鼠体内的血吸虫雄虫经Art作用后 12和 2 4h ,其脂质过氧化物水平均有明显升高。体外 ,Art或hemin单一作用血吸虫 2 4h ,对其TBARs水平无影响 ,但Art(15～ 6 0 μmol/L)与hemin(10～ 5 0 μmol/L)伍用可导致虫体的TBARs水平明显升高。结论Art具有血红素依赖的诱发日本血吸虫脂质过氧化作用。     

吡喹酮衍生物DW-3-15对日本血吸虫PZQ抗性虫体的生物学效应观察北大核心CSCD

目的通过体外观察吡喹酮(PZQ)衍生物DW-3-15对日本血吸虫PZQ抗性虫体的生物学效应,探讨该衍生物作为抗日本血吸虫候选新药的潜在价值。方法单性日本血吸虫尾蚴(70±5条)感染小鼠,21d后,用PZQ的半数有效剂量(ED50,25.98mg/kg)对小鼠进行灌胃给药,每天一次,连续30d,停药21d后,再给予小鼠治疗剂量PZQ(200mg/kg),连续5d,停药2周后肝门静脉灌注收集虫体,置DMEM培养液中培养,分别加入不同浓度PZQ和DW-3-15,作用16h后换新鲜培养液,继续培养72h,每隔24h体视显微镜下观察、记录一次虫体活力和形态变化,评价诱导虫体对PZQ及DW-3-15的敏感性。结果 PZQ和DW-3-15体外作用于未诱导日本血吸虫成虫的临界致死浓度(作用虫体72h活力降低率达90%的最低浓度)分别为14μmol/L和45μmol/L;诱导虫体对PZQ的敏感性较未诱导虫体显著下降,是其临界致死浓度的8倍(112μmol/L),而诱导虫体对DW-3-15的敏感性与未诱导虫体相比没有明显差异,临界致死浓度仍为45μmol/L。结论经诱导的日本血吸虫PZQ抗性虫体对DW-3-15没有交叉抗性;提示DW-3-15抗日本血吸虫的靶点可能与PZQ不同,具有作为抗日本血吸虫候选新药的潜在价值,值得进一步研究。     

钙通道阻滞剂与肌动蛋白解聚/稳定剂对吡喹酮体外杀日本血吸虫作用的效应影响

目的探索吡喹酮(praziquantel,PZQ)对日本血吸虫的药物靶点及作用机制。方法在日本血吸虫单性尾蚴感染昆明小鼠6 w后,采用灌注法经鼠肝门静脉收集日本血吸虫雄性成虫。在DMEM(Dulbecco-modified Mini mum Eagle'Medium)培养液内,将雄性成虫分别与能干扰细胞钙通道功能的各种药理学成分(钙通道阻滞剂及肌动蛋白解聚剂或稳定剂)孵育1h,然后在培养液内加入临界致死剂量的PZQ(14μmol/L)与虫体孵育过夜(16h)。次,无菌生理盐水洗涤虫体3次,更换无药物的新鲜培养液继续培养虫体5d,每天置于体视显微镜下观察并记录。结果d晨上午正常情况下,14μmol/L的PZQ药物体外实验可以杀死大部分日本血吸虫雄性成虫,而与肌动蛋白解聚剂细胞松弛素D(cytochalasin D,CyD)预孵育1h的虫体,能够完全拮抗14μmol/L浓度PZQ的杀虫效应,虫体100%存活;与钙通道阻滞剂(calciumchannel blockers,CCBs)尼群地平和尼非地平预孵育1h的虫体,部分拮抗14μmol/L浓度PZQ的杀虫效应,大约50%虫体存活。结论PZQ作用血吸虫的药物靶点可能与血吸虫的钙通道有关。     

几种药物对体外培养日本血吸虫成虫毒性作用的研究

目的观察金诺芬、顺铂、阿霉素及化合物4N、H、B、O对体外培养日本血吸虫的毒性作用,以及对硫氧还蛋白谷胱甘肽还原酶（TGR）活性的抑制作用。方法取日本血吸虫成虫置于RPMI 1640培养基中,培养30～60 min后,加入不同浓度药物,分别于6、24、48、72 h观察虫体活力、形态改变及死亡情况。随后换无药物的新鲜培养基,观察虫体活力的恢复情况,并计算药物半数致死剂量（LD50）。测定药物处理后的成虫匀浆上清液中日本血吸虫TGR的硫氧还蛋白原酶（TrxR）和谷胱苷肽还原酶（GR）的活性。结果 5μg/ml金诺芬作用24 h、20μg/ml 4N作用72 h、60μg/ml H作用72 h、80μg/ml顺铂作用72 h对日本血吸虫成虫致死率分别为100%、60%、66.7%、100%,LD50值分别为2.56、17.59、54.14μg/ml和52.87μg/ml,其他药物对日本血吸虫无作用。金诺芬、4N、顺铂、H对成虫的毒性作用具有不可逆性;金诺芬、顺铂对日本血吸虫的TGR酶活性有抑制作用,其他药物对TGR无作用。5～30μg/ml金诺芬、20～30μg/ml 4N、70～150μg/ml顺铂及60～150μg/ml H作用24 h均可使虫体形态发生改变。结论金诺芬、顺铂、化合物4N和H对体外培养的日本血吸虫成虫具有杀伤作用,其中金诺芬、顺铂杀伤日本血吸虫成虫的作用可能与其抑制TGR活性有关。     

青蒿琥脂对人卵巢癌细胞株HO8910增殖的影响及机制探讨

目的观察青蒿琥酯(Art)对人卵巢癌细胞株HO8910增殖的影响,并探讨其机制。方法采用MTT法观察不同浓度(5、10、20、40、80μmol/L)Art对HO8910细胞增殖的影响,通过流式细胞仪观察20μmol/LArt对HO8910细胞周期的影响,采用Western blot法检测不同浓度(5、10、20、40、80μmol/L)Art对HO8910细胞Bcl-2、Bax表达的影响。结果随着Art浓度增加及作用时间的延长,H08910细胞增殖抑制率明显升高(P均<0.05),呈一定的时间、剂量依赖性。20μmol/LArt作用HO8910细胞24、36 h后,G_0/G_1期细胞所占比例显著增加(P<0.01);作用36、48 h,Sub G_1细胞所占比例显著增加(P<0.01)。经过不同浓度Art处理48 h后,Bcl-2表达水平显著降低(P<0.01),Bax表达水平升高(P<0.01),并呈一定剂量相关性。结论 Art对卵巢癌HO8910细胞的增殖有抑制作用,该作用可能与其下调Bcl-2及上调Bax蛋白表达有关。     

白藜芦醇对人肾癌细胞增殖和细胞周期的影响

目的探讨白藜芦醇（Res）对人肾癌细胞786-0（以下简称肾癌细胞）增殖和周期的影响。方法分别采用12.5、25、50、100μmol/L的白藜芦醇（Res）作用于肾癌细胞24 h;并设空白对照组。流式细胞仪检测细胞细胞周期。结果各浓度Res对肾癌细胞增殖均具有明显的抑制作用,表现为G1期及G2期细胞比例明显降低,S期比例明显升高,与对照组比较,P均〈0.05。Res 12.5μmol/L与25、50及100μmol/L比较,P均〈0.05;但25μmol/L与50、100μmol/L比较,P〉0.05。12.5μmol/L的Res抑制作用明显,当浓度达到25μmol/L时,抑制作用达最强;而继续升高浓度不能提高抑制作用。结论 Res对人肾癌细胞增殖有抑制作用,且具有剂量依赖性。     

辛伐他汀对血管内皮细胞内皮素-1表达的抑制作用

目的观察羟甲基戊二酰辅酶A（HMG-COA）还原酶抑制剂-辛伐他汀（Simvastatin）对培养的血管内皮细胞表达内皮素-1（ET-1）的影响。方法采用辛伐他汀以不同浓度和不同作用时间对培养的人脐静脉内皮细胞进行干预,并用甲羟戊酸调节辛伐他汀的作用,分别采用半定量逆转录聚合酶链反应（RT-PCR）和酶联免疫吸附试验（ELISA）检测内皮细胞ET-1 mRNA的表达和上清液中ET-1的浓度。结果（1）辛伐他汀以浓度依赖方式抑制内皮细胞ET-1的表达。1μmol/L的辛伐他汀对内皮细胞ET-1 mRNA和ET-1表达没有影响,2.5μmol/L辛伐他汀即表现出抑制作用,5μmol/L及10μmol/L时则更加明显（P〈0.01）;（2）辛伐他汀以时间依赖方式抑制内皮细胞ET-1的表达。与对照组相比,以10μmol/L辛伐他汀干预内皮细胞12h后,内皮细胞ET-1 mRNA和ET-1表达明显减少,24h后继续减低,36h则更加明显（P〈0.01）;（3）100μmol/L甲羟戊酸可以阻止辛伐他汀对血管内皮细胞表达ET-1 mRNA和ET-1的抑制作用。结论辛伐他汀可抑制培养的血管内皮细胞合成和分泌ET-1。     

三氧化二砷抑制血小板聚集功能的研究

目的:分析三氧化二砷(ATO)对血小板聚集功能的影响。方法:用不同浓度的ATO(0、0.25、0.5、1、1.5、2、2.5、5和10μmol/L)孵育富血小板血浆(PRP)0、3、15、30、45和60 min,在2 mg/L胶原或2μmol/L腺苷二磷酸(ADP)刺激下,检测血小板聚集功能。结果:在刺激剂为2 mg/L胶原时,ATO(≥5μmol/L)孵育PRP 60 min,可显著抑制血小板聚集,在相应的时间梯度实验中,ATO浓度从5μmol/L上升到10μmol/L,抑制血小板聚集所需要的孵育时间从45 min下降到30 min,ATO对胶原诱导的血小板聚集具有浓度(r=-0.902,P=0.001)和时间(r=-0.964,P=0.002;r=-0.910,P=0.032)依赖性;在刺激剂为2μmol/L ADP时,ATO(≥2μmol/L)孵育PRP 60 min,可显著抑制血小板聚集,在相应的时间梯度实验中,ATO浓度从5μmol/L上升到10μmol/L,抑制血小板聚集所需要的孵育时间从45 min下降到15 min,ATO对ADP诱导的血小板聚集亦具有浓度(r=-0.815,P=0.007)和时间(r=-0.921,P=0.009;r=-0.963,P=0.009)依赖性。结论:低浓度的ATO对血小板聚集功能没有明显的作用,但是高浓度ATO(≥2μmol/L)可抑制血小板的聚集功能,并且该抑制作用具有浓度和时间依赖性。     

三氧化二砷抑制血小板聚集功能的研究

目的:分析三氧化二砷(ATO)对血小板聚集功能的影响。方法:用不同浓度的ATO(0、0.25、0.5、1、1.5、2、2.5、5和10μmol/L)孵育富血小板血浆(PRP)0、3、15、30、45和60 min,在2 mg/L胶原或2μmol/L腺苷二磷酸(ADP)刺激下,检测血小板聚集功能。结果:在刺激剂为2 mg/L胶原时,ATO(≥5μmol/L)孵育PRP 60 min,可显著抑制血小板聚集,在相应的时间梯度实验中,ATO浓度从5μmol/L上升到10μmol/L,抑制血小板聚集所需要的孵育时间从45 min下降到30 min,ATO对胶原诱导的血小板聚集具有浓度(r=-0.902,P=0.001)和时间(r=-0.964,P=0.002;r=-0.910,P=0.032)依赖性;在刺激剂为2μmol/L ADP时,ATO(≥2μmol/L)孵育PRP 60 min,可显著抑制血小板聚集,在相应的时间梯度实验中,ATO浓度从5μmol/L上升到10μmol/L,抑制血小板聚集所需要的孵育时间从45 min下降到15 min,ATO对ADP诱导的血小板聚集亦具有浓度(r=-0.815,P=0.007)和时间(r=-0.921,P=0.009;r=-0.963,P=0.009)依赖性。结论:低浓度的ATO对血小板聚集功能没有明显的作用,但是高浓度ATO(≥2μmol/L)可抑制血小板的聚集功能,并且该抑制作用具有浓度和时间依赖性。     

赛格列酮能抑制血管紧张素Ⅱ诱导的人内皮细胞表面粘附分子上调

目的研究赛格列酮对血管紧张素Ⅱ诱导人脐静脉内皮细胞表达细胞间粘附分子1和血管细胞粘附分子1上调的影响。方法以不同浓度的赛格列酮(0.1μmol/L、1μmol/L1、0μmol/L和100μmol/L)预处理人脐静脉内皮细胞24 h,再与10-7mmol/L血管紧张素Ⅱ共孵育12 h。通过半定量逆转录聚合酶链反应和Western Blot分别检测细胞间粘附分子1和血管细胞粘附分子1 mRNA和蛋白表达的情况。结果与血管紧张素Ⅱ组相比,0.1μmol/L和1μmol/L赛格列酮预处理24 h组对血管紧张素Ⅱ诱导人脐静脉内皮细胞表达细胞间粘附分子1 mRNA上调无抑制作用(1.107±0.091比1.104±0.081和1.062±0.051,P>0.05),而10μmol/L和100μmol/L组则有明显的抑制作用(0.814±0.016和0.766±0.026,P<0.01和P<0.001);细胞间粘附分子1蛋白表达分别下调52.9%和55.5%(P<0.01和P<0.001)。而不同浓度的赛格列酮(0.1μmol/L、1μmol/L、10μmol/L和100μmol/L)使血管细胞粘附分子mRNA表达分别下调14.2%、19.5%、45.1%和60.7%(0.1μmol/L时P<0.01,余P<0.001);蛋白表达分别下调17.8%、33.8%、54.5%和58.9%(0.1μmol/L时P<0.01,余P<0.001)。结论赛格列酮抑制血管紧张素Ⅱ上调人脐静脉内皮细胞表达血管细胞粘附分子1,并呈浓度依赖效应;但对细胞间粘附分子1无论是mRNA还是蛋白水平,在低浓度(0.1μmol/L和1μmol/L)时无抑制作用,在较高浓度(10μmol/L和100μmol/L)可有较明显的抑制作用。     

胰岛素瘤的解剖分布特点分析

目的胰岛素瘤是最常见的胰腺神经内分泌肿瘤，因其临床表现多样，导致诊断困难。影像学诊断尤其是超声内镜(EUS)在胰岛素瘤的诊断中起着重要作用，拥有较高的敏感性和特异性。本研究拟通过明确胰岛素瘤的解剖分布特点，以期有助于提高影像学的诊断准确率和降低漏诊率，尤其是在教育和培训实践中对于EUS的学习者更具有指导价值。 方法回顾性分析解放军总医院第一医学中心病案资料数据库1993年1月至2019年11月经外科手术、病理确诊为胰岛素瘤的患者的临床资料，检索方法采取搜索术后病理诊断为"胰岛素瘤"的病例，通过查阅病例的方法，提取出胰岛素瘤的大小和解剖分布等数据，进一步分析其特点。 结果共检索到确诊为胰岛素瘤的患者116例，其中，男45例、女71例，年龄13～76岁，平均年龄(44.4±14.85)岁。胰岛素瘤单发110例(94.8%)、多发6例(5.2%)。位置分布：头颈部46例(39.7%)，单发45例、多发1例；体尾部68例(58.6%)，单发65例、多发3例；全胰腺多发2例(1.7%)。病变大小特点：最大径0.4～3.4 cm，平均大小(1.53±0.58)cm。≤1 cm 29例、>1 cm而≤1.5 cm41例、>1.5 cm而≤2.0 cm28例，≤3 cm 15例，>3 cm 3例。年龄与肿瘤的大小相关，≤44岁患者肿瘤平均大小为(1.36±0.51)cm、>44岁患者肿瘤平均大小为(1.70±0.60)cm，P<0.05。头颈部的肿瘤大于体尾部的肿瘤，头颈部肿瘤平均大小(1.66±0.63)cm，体尾部(1.42±0.52)cm，P<0.05。 结论胰岛素瘤在胰腺体尾部较头颈部更好发；绝大多数单发，但可以全胰腺多发；多数小于1.5 cm，肿瘤的大小与患者年龄和肿瘤的解剖分布相关。     

Pathogenesis of carcinoma of the papilla of Vater

Most adenomas and carcinomas of the small intestine and extrahepatic bile ducts arise in the region of the papilla of Vater. In familial adenomatous polyposis (FAP) it is the main location for carcinomas after proctocolectomy. In many cases symptoms due to stenosis lead to diagnosis at an early tumor stage. In about 80%, curative intended resection is possible. Operability is the most relevant prognostic factor. Most ampullary carcinomas resp. carcinomas of the papilla of Vater develop from adenomatous or flat dysplastic precursor lesions. They can be sited in the ampulloduodenal part of the papilla of Vater, which is lined by intestinal mucosa. They also can develop in deeper parts of the ampulla, which are lined by pancreaticobiliary duct mucosa. Intestinal-type adenocarcinoma and pancreaticobiliary-type adenocarcinoma represent the main histological types of ampullary carcinoma. Furthermore, there exist unusual types and undifferentiated carcinomas. Many carcinomas of intestinal type express the immunohistochemical marker profile of intestinal mucosa (keratin 7?, keratin 20+, MUC2+). Carcinomas of pancreaticobiliary type usually show the immunohistochemical profile of pancreaticobiliary duct mucosa (keratin 7+, keratin 20?, MUC2?). Even poorly differentiated carcinomas, as well as unusual histological types, may conserve the marker profile of the mucosa they developed from. These findings underline the concept of histogenetically different carcinomas of the papilla of Vater which develop either from intestinal- or from pancreaticobiliary-type mucosa of the papilla of Vater. Molecular alterations in ampullary carcinomas are similar to those of colorectal as well as pancreatic carcinomas, although they appear at different frequencies. In future studies, molecular alterations in ampullary carcinomas should be correlated closely with the different histologic tumor types. Consequently, the histologic classification should reflect the histogenesis of ampullary tumors from the two different types of papillary mucosa.     

Demonstration of the mechanism of action of biguanides

Summary Palmitic acid oxidation in rat diaphragm homogenate is depressed by biguanide concentrations that are still incapable of inhibiting oxidative phosphorylation. Glucose oxidation is not directly effected by the same biguanide concentrations: however, the inhibitory effect of palmitic acid on glucose oxidation is partly removed by biguanides. Inhibition of fatty acid oxidation, which accounts for most of the metabolic effects caused by these drugs, can be regarded as the fundamental mechanism of action of biguanides. There is some evidence suggesting that these drugs might interact with carnitine, thus preventing long-chain fatty acids from being transported across the mitochondrial membrane to the site of oxidation. Traduzione a cura degli AA.     

Lack of correlation of degree of villous atrophy with severity of clinical presentation of coeliac disease

BACKGROUND AND AIM: Both the clinical presentation and the degree of mucosal damage in coeliac disease vary greatly. In view of conflicting information as to whether the mode of presentation correlates with the degree of villous atrophy, we reviewed a large cohort of patients with coeliac disease. PATIENTS AND METHODS: We correlated mode of presentation (classical, diarrhoea predominant or atypical/silent) with histology of duodenal biopsies and examined their trends over time. RESULTS: The cohort consisted of 499 adults, mean age 44.1 years, 68% females. The majority had silent coeliac disease (56%) and total villous atrophy (65%). There was no correlation of mode of presentation with the degree of villous atrophy (p=0.25). Sixty-eight percent of females and 58% of males had a severe villous atrophy (p=0.052). There was a significant trend over time for a greater proportion of patients presenting as atypical/silent coeliac disease and having partial villous atrophy, though the majority still had total villous atrophy. CONCLUSIONS: Among our patients the degree of villous atrophy in duodenal biopsies did not correlate with the mode of presentation, indicating that factors other than the degree of villous atrophy must account for diarrhoea in coeliac disease.     

血吸虫童虫生长发育及其机制的研究进展

血吸虫童虫是宿主免疫系统攻击的重要靶标,包括皮肤型、肺型和肝门型童虫。宿主分子对童虫生长发育具有重要作用。童虫生长发育机制包括免疫调节、信号转导、性别发育及凋亡等。肌动蛋白、组织蛋白酶、烯醇化酶和葡萄糖基转移酶等分子为血吸虫童虫生长发育的重要分子。本文对血吸虫童虫生长发育及其机制的研究进展做一综述。     

氯硝柳胺悬浮剂的毒性评价

目的评价氯硝柳胺悬浮剂的毒性，为现场大规模应用灭螺提供依据。方法按照中华人民共和国国家标准GB 15670-1995《农药登记毒理学试验方法》和鱼类毒性试验方法进行。结果经口、经皮肤的LDso雌、雄性大鼠均>5 000 mg/kg，经呼吸道的LCso雌、雄性大鼠均>5 000mg/m3，该药经口、经皮肤、经呼吸道毒性均属微毒类药物；兔眼用药后，观察期内无不良反应，对眼无刺激性；皮肤用药后对皮肤无刺激性。与氯硝柳胺原药、氯硝柳胺乙醇胺盐原药和氯硝柳胺乙醇胺盐可湿性粉剂相比，氯硝柳胺悬浮剂对鱼急性毒性最低。结论氯硝柳胺悬浮剂属微毒类药物，对鱼的毒性低于其乙醇胺盐可湿性粉剂，适合于现场应用。     

124例耐多药结核分枝杆菌基因突变特征分析

目的对临床分离的耐多药结核分枝杆菌相关基因的突变特征进行分析。方法对124例耐多药结核分枝杆菌以及50株敏感株的耐药相关基因(包括异烟肼inh A、kat G、oxyR-ahp C间隔区以及利福平rpo B)进行序列测定,分析其基因突变情况。结果异烟肼耐药inh A基因突变率为14.5%;kat G基因突变率为70.2%(87/124),主要位于315位;oxyR-ahp C间隔区突变率为15.3%;inh A、kat G两种基因同时突变率75.0%,三种基因同时突变率为89.5%。利福平rpo B基因突变的检出率高达95.2%,突变主要发生在531、526、516位点。结论我省耐多药菌异烟肼耐药相关基因最常见突变为kat G 315、inh A C-T(-15)、axyR-ahp C间隔区(-10)C-T,利福平为rpo B531、526、516。结合MDR-TB耐药相关基因的特征分析,可以建立一种快速、准确、特异的适合于我省的检测结核菌耐多药性的新方法。     

Assessment of quality of life of parents of children with juvenile chronic arthritis

The aim of the study was to assess the quality of life (QOL) and the psychological status of parents of children with juvenile chronic arthritis (JCA). The QOL, anxiety and depression of the parents of 28 children with JCA were evaluated and compared to those of the parents of 28 healthy children. Mothers of JCA children and mothers of healthy children reported similar QOL. The reported anxiety and depression levels were similar for mothers and fathers in both groups. The parents of children with pauciarticular-type JCA reported lower QOL and higher levels of anxiety and depression than the parents of children with other types, namely polyarticular and systemic JCA. These findings may be explained by the fact that the pauciarticular patients had shorter disease duration and were less frequently seen in the outpatient clinic. The QOL of mothers of children with JCA was found to be slightly impaired in the group of children with pauciarticular JCA. Future larger studies are needed to confirm these results, as the number of subjects in the three groups was rather low. Received: 26 September 2001 / Accepted: 8 February 2002     

Numerical Simulation of the Effect of Rate of Change of Glucose on Measurement Error of Continuous Glucose Monitors

Background

A 5-day in-patient study designed to assess the accuracy of the FreeStyle Navigator® Continuous Glucose Monitoring System revealed that the level of accuracy of the continuous sensor measurements was dependent on the rate of glucose change. When the absolute rate of change was less than 1 mg•dl⁻¹•min⁻¹ (75% of the time), the median absolute relative difference (ARD) was 8.5%, with 85% of all points falling within the A zone of the Clarke error grid. When the absolute rate of change was greater than 2 mg•dl⁻¹•min⁻¹ (8% of the time), the median ARD was 17.5%, with 59% of all points falling within the Clarke A zone.

Method

Numerical simulations were performed to investigate effects of the rate of change of glucose on sensor measurement error. This approach enabled physiologically relevant distributions of glucose values to be reordered to explore the effect of different glucose rate-of-change distributions on apparent sensor accuracy.

Results

The physiological lag between blood and interstitial fluid glucose levels is sufficient to account for the observed difference in sensor accuracy between periods of stable glucose and periods of rapidly changing glucose.

Conclusions

The role of physiological lag on the apparent decrease in sensor accuracy at high glucose rates of change has implications for clinical study design, regulatory review of continuous glucose sensors, and development of performance standards for this new technology. This work demonstrates the difficulty in comparing accuracy measures between different clinical studies and highlights the need for studies to include both relevant glucose distributions and relevant glucose rate-of-change distributions.     

Study of constancy of hydrogen-consuming flora of human colon

The constancy of the hydrogen consuming flora of the human colon was studied in 15 healthy subjects via two measurements obtained 18 to 36 months apart. Hydrogen disappearance rate and the major products of H₂-consuming bacteria, methane and sulfide, were measured during incubation of fecal homogenates with excess hydrogen and sulfate. In 11/15, the hydrogen consumption rate and the predominant hydrogen-consuming pathway (methanogenesis, sulfate reduction, or neither) remained constant. However, major shifts in these pathways were observed in four subjects, with two losing and two gaining the ability to produce methane. Methanogenesis was associated with the highest hydrogen consumption rate. This study demonstrates that clinically unrecognizable, major alterations of the colonic flora occur in healthy subjects. Understanding of the factors responsible for these alterations might allow for therapeutic manipulation of the colonic flora.Supported in part by the Department of Veterans Affairs and NIDDKD RO1 DK 13309-25.