人参皂甙与已烯雌酚联用对去卵巢大鼠骨丢失作用的观察

目的探讨人参皂甙单用或与己烯雌酚合用对去卵巢大鼠骨丢失的预防作用.方法 4.5月龄SD雌性大鼠,按体重随机分为正常对照组、去卵巢组、己烯雌酚组、人参皂甙组和人参皂甙与己烯雌酚联用组.采用双侧卵巢摘除术,体内双荧光标记法,胫骨上段硬组织包埋切片,全自动图像分析及松质骨形态计量学软件处理,观察药物对骨形态计量参数的影响.结果去卵巢10 w后骨量丢失和破骨细胞活性、骨形成率及骨转换率增加,子宫重量减轻,子宫内膜厚度变薄,存在显著性差异(P＜0.01或P＜0.05).人参皂甙与己烯雌酚合用能使骨量增加,骨形成增多,骨吸收和骨转换率下降并有显著性差异(P＜0.01或P＜0.05),子宫重量和子宫内膜厚度均下降.结论去卵巢大鼠骨量丢失,骨转换率增高,出现明显的骨质疏松;己烯雌酚(10μg@kg-1@d-1)能抑制骨吸收,也抑制骨形成.与100 mg/kg人参皂甙合用,能增加骨量,增加骨形成,并减轻己烯雌酚导致的子宫重量增加和内膜增厚的危险性,能完全预防去卵巢大鼠的骨丢失.     

强骨宝对去势大鼠骨形态计量学影响的研究

目的 观察强骨宝（黄芪＋司坦唑醇,JGB）对去卵巢大鼠骨质疏松症骨形态计量学参数的影响.方法 取32只Wistar雌性大鼠随机分为4组,行去势手术,制成去卵巢大鼠骨质疏松模型.然后分别灌胃给药生理盐水、己烯雌酚、强骨宝,8 w后处死,取大鼠胫骨上段松质骨和中段皮质骨硬组织包埋、切片,图像分析松质骨、皮质骨形态计量学参数.结果 强骨宝可使去卵巢大鼠松质骨静态参数和动态参数显著增加,吸收参数显著降低;皮质骨面积、骨髓腔面积等静态及内外骨膜骨形成动态参数均无显著变化,内膜面骨吸收参数降低.结论 强骨宝能有效预防去卵巢大鼠骨质疏松症松质骨丢失,亦具有抑制皮质骨内膜骨吸收的作用.     

人参皂甙与己烯雌酚联用对去卵巢大鼠骨丢失作用的观察

目的　探讨人参皂甙单用或与己烯雌酚合用对去卵巢大鼠骨丢失的预防作用。方法　 4.5月龄 SD雌性大鼠 ,按体重随机分为正常对照组、去卵巢组、己烯雌酚组、人参皂甙组和人参皂甙与己烯雌酚联用组。采用双侧卵巢摘除术 ,体内双荧光标记法 ,胫骨上段硬组织包埋切片 ,全自动图像分析及松质骨形态计量学软件处理 ,观察药物对骨形态计量参数的影响。结果　去卵巢 1 0 w后骨量丢失和破骨细胞活性、骨形成率及骨转换率增加 ,子宫重量减轻 ,子宫内膜厚度变薄 ,存在显著性差异 (P<0 .0 1或 P<0 .0 5)。人参皂甙与己烯雌酚合用能使骨量增加 ,骨形成增多 ,骨吸收和骨转换率下降并有显著性差异 (P<0 .0 1或 P<0 .0 5) ,子宫重量和子宫内膜厚度均下降。结论　去卵巢大鼠骨量丢失 ,骨转换率增高 ,出现明显的骨质疏松 ;己烯雌酚 (1 0μg· kg- 1· d- 1 )能抑制骨吸收 ,也抑制骨形成。与 1 0 0 mg/ kg人参皂甙合用 ,能增加骨量 ,增加骨形成 ,并减轻己烯雌酚导致的子宫重量增加和内膜增厚的危险性 ,能完全预防去卵巢大鼠的骨丢失     

复方淫羊藿对去卵巢大鼠腰椎松质骨的影响

目的 观察淫羊藿提取物与乙烯雌酚（DES）组成复方淫羊藿对去卵巢大鼠腰椎松质骨的影响。方法 4.5月龄SD雌性大鼠70只，随机分成假手术组、去卵巢组、DES组、淫羊藿提取物组、复方淫羊藿高、中、低剂量组，持续给药90d。大鼠处死后用骨组织形态计量学等方法测量腰椎松质骨的动态参数和静态参数，同时测量子宫内膜厚度。结果 复方淫羊藿3个剂量组的腰椎％TbAr、Tb.Th均高于去卵巢组，而Tb.Sp、Oe.N、BFR／BV均低于去卵巢组。复方淫羊藿商剂量组的作用比单用DES强，而低剂量组的作用与DES相当。复方淫羊藿3个剂量组子宫重量、子宫内膜厚度均高于去卵巢组，但子宫内膜厚度均小予DES组。结论 复方淫羊藿预防去卵巢大鼠腰椎松质骨丢失的作用强于DES，对子宫刺激的作用比DES小。     

何首乌煎剂对去卵巢大鼠骨质丢失的防治作用

目的探讨何首乌煎剂对去卵巢大鼠骨丢失的骨组织形态计量学改变及预防作用。方法大鼠双侧卵巢去除术(OVX)后预防用药90d。骨标本行不脱钙骨制片,骨组织形态计量学测量胫骨近心端松质骨静态和动态参数。结果去卵巢大鼠骨小梁面积百分率(%Tb.Ar)减少(P<0.05),出现高转换型骨质疏松:己烯雌酚可完全对抗去卵巢大鼠的体重增加、骨转换率增高和骨量丢失;何首乌煎剂使去卵巢大鼠的%Tb.Ar增加(P<0.05)、骨吸收减少、骨转换率呈下降趋势,不抑制藕联的骨形成。结论何首乌煎剂对去卵巢大鼠骨丢失有一定的预防作用,且对子宫无明显刺激。     

己烯雌酚对去卵巢大鼠密质骨影响的定量研究

将２７只３月龄ＳＤ雌大白鼠随机分为基础对照组（Ａ）、年龄对照组（Ｂ）、去卵巢组（Ｃ）和去卵巢加己烯雌酚（ＤＥＳ）治疗组（Ｄ）。Ｂ组和Ｃ组用生理盐水５ｍｌ·ｋｇ－１／ｄ．ｉｇ，Ｄ组用浓度为４．５ｍｇ／Ｌ的己烯雌酚按５ｍｌ·ｋｇ－１／ｄ．ｉｇ，每周６次。１２周后，对各组大鼠胫骨中段不脱钙骨片进行骨计量学分析。去卵巢大鼠由于骨吸收大于骨形成，密质骨变薄，骨髓腔扩大，出现高转换型骨质疏松，己烯雌酚能明显抑制去卵巢后的骨高转换，保持密质骨厚度，维持骨量的正常。     

中药复方护骨胶囊对去卵巢大鼠骨骼结构和骨重建状态的影响

目的观察护骨胶囊(Hugu capsules,HG)对去卵巢大鼠骨结构和骨重建状态的影响。方法 3月龄SPF级雌性SD大鼠60只采用数字表法随机分为假手术组,去卵巢组,仙灵骨葆胶囊组和护骨胶囊低、中、高剂量组(Sham、OVX、Pos、HG-L、HG-M和HG-H)。大鼠切除卵巢后,隔天开始给药,连续灌胃3个月,处死前进行两次荧光标记。取大鼠胫骨上段(proximal tibia,PTM)与中段(tibia shaft,TX)进行骨形态计量学分析。结果与Sham组比较:OVX组松质骨的骨小梁面积百分率(percent trabecular bone area,Tb.Ar)和骨小梁数量(trabecular number,Tb.N)分别降低66.68%和65.01%,骨小梁分离度(trabecular seperation,Tb.Sp)增加276.97%。单位骨小梁周长成骨细胞数(osteoblast number/unit trabecular perimeter,Ob.N)和成骨细胞周长百分率(percent osteoblast perimeter,Ob.Pm)分别增加357.53%和468.27%,单位骨小梁周长破骨细胞数(osteoclast number/unit trabecular perimeter,Oc.N)和破骨细胞周长百分率(percent osteoclast perimeter,Oc.Pm)分别增加213.95%和216.67%,骨形成率-体积(bone formation rate/volume,BFR/BV)增加39.12%,骨形成率-组织(bone formation rate/tissue,BFR/TV)降低55.56%,提示松质骨骨质疏松造模成功。皮质骨没有变化;与OVX组比:HG组大鼠松质骨的Tb.Ar、Tb.N和骨小梁宽度(trabecular width,Tb.Wi)增加,Tb.Sp、Oc.N、Oc.Pm降低,荧光周长百分率(percent fluorescence perimeter,L.Pm)、骨形成率-周长(bone formation rate/bone surface,BFR/BS)、BFR/BV和骨形成率-组织(bone formation rate/tissue,BFR/TV)增加。HG组大鼠皮质骨的T.Ar、Ct.Ar、骨外膜荧光标记周长百分率(percent periosteal fluorescence perimeter,P-L.Pm)和骨外膜骨形成率(periosteal bone formation rate/bone surface,P-BFR/BS)均增加。说明HG能增加松质骨骨量,改善骨结构,促进骨形成,抑制骨吸收,且增加皮质骨骨量,促进皮质骨骨外膜骨形成;与Pos组相比:HG-H组的松质骨Tb.N增加23.80%,Tb.Sp降低22.71%,HG-L和HG-M组的L.Pm、BFR/BS、BFR/BV和BFR/TV显著升高。在皮质骨方面,HG-L和HG-M组的P-L.Pm分别升高234.99%和182.58%,HG-L组的P-BFR/BS增加229.13%。结论 HG增加去卵巢大鼠的骨量,改善骨组织结构。HG具有促进6月龄OVX骨高转换大鼠骨形成的作用,在此年龄段促进骨形成方面效果可能优于Pos。为临床应用HG提供了良好的实验依据。     

去卵巢大鼠不同时期皮质骨与松质骨变化的显微CT观察

目的 应用显微CT观察去卵巢大鼠胫骨近端皮质骨与松质骨骨密度和骨微结构差异. 方法40只7月龄SD大鼠,随机分为去卵巢(OVX)组和假手术(SHAM)组,每组20只,于手术后第3周及第15周处死.处死后剥离左侧胫骨,行显微CT三维扫描,扫描完成后选取距生长板远端2.5 mm、层厚0.4 mm骨组织为皮质骨感兴趣区域,选取距生长板远端0.7 mm、层厚1.2 mm骨组织为松质骨感兴趣区域行三维重建.获取二维最大密度投射图像及三维结构图像,并对感兴趣区的皮质骨和松质骨进行定量分析. 结果 3周时,OVX和SHAM组大鼠皮质骨面积分别为(0.43±0.13)、(0.31±0.06)mm2;骨髓腔面积(10.31±1.98)、(8.44±1.25)mm2,截面总面积(10.74±2.05)、(8.75±1.26)mm2,截面惯性矩(4.10±0.73)、(3.49±0.37)mm4,两组比较差异有统计学意义(均为P＜0.05).第15周时,除OVX组皮质骨平均厚度低于SHAM组外(P＜0.05),其余各参数两组比较差异无统计学意义.15周OVX组大鼠左侧胫骨骨丢失敏感区域内皮质骨平均厚度和皮质骨面积较3周OVX组大鼠下降(P＜0.05).SHAM组15周大鼠骨内径周长、骨外径周长和截面惯性矩增大,与3周比较,差异有统计学意义(P＜0.05).3周时,OVX和SHAM组体积骨密度分别为(288.2±48.2)mg/mm3和(408.4±51.6)mg/mm3、组织骨密度(604.5±45.3)mg/mm3和(686.7±40.0)mg/mm3、骨体积分数(25.1±5.1)%和(33.6±4.1)%、骨小梁数量(6.04±2.94)个/mm和(9.85±2.83)个/mm,两组比较差异有统计学意义(均为P＜0.05),结构模型指数(分别为3.11±0.36)和2.58±0.36),小梁间隔为(0.37±0.22)mm和(0.14±0.10)mm,明显高于SHAM组(P＜0.05).第15周时,OVX组体积骨密度、骨体积分数、骨小梁数量、结构模型指数和骨小梁间隔改变与SHAM组比较,差异有统计学意义(均为P＜0.05),但组织骨密度差别消失.OVX组大鼠15周较3周组织骨密度增加、骨小梁厚度增厚、骨小梁数量减少和骨小梁间隔增宽(P＜0.05). 结论 大鼠去卵巢后,胫骨近端皮质骨与松质骨具有不同的骨量丢失方式和不同的微结构改变.早期松质骨骨密度明显下降,骨微结构发生退变;皮质骨厚度减少,其微结构改变则先于骨密度的下降,骨量在去卵巢后15周变化不大.     

大鼠肾性骨病模型皮质骨骨量及结构的变化

目的:观察腺嘌呤联合高磷饮食建立的肾性骨病模型大鼠的皮质骨骨量和骨结构的形态学变化,并探讨其骨矿代谢情况及机制。方法:3月龄雄性SD大鼠24只,随机分为腺嘌呤模型组(M组,1~4周予含腺嘌呤的高磷饮食,5~6周高磷饮食饲养)和高磷饮食对照组(C组,高磷饮食饲养6周);皮下注射钙黄绿素进行体内双荧光标记,处死大鼠后取左侧胫骨中段不脱钙包埋制备骨标本,骨组织形态计量学分析骨量和骨结构变化情况。结米:静态参数显示:与C组相比,M组骨组织总面积明显变小、皮质骨面积百分比和皮质骨厚度显著降低,骨髓腔面积百分比明显增大;胫骨皮质上出现侵蚀小孔。动态参数显示:与C组相比,M组骨外膜面荧光标记周长百分比无显著变化,但骨矿化沉积率、骨形成率明显增加;骨内膜面荧光标记周长百分比、骨矿化沉积率明显提高,骨形成率和骨吸收周长百分数明显增加。结论:腺嘌呤作用下高磷饮食大鼠胫骨皮质骨的骨外膜、内膜的骨形成和吸收活跃;皮质骨内外膜骨量丢失,说明骨吸收大于骨形成、骨偶联失衡而导致皮质厚度减少,处于明显的骨高转化代谢状态。     

中等强度跑台运动对去卵巢大鼠骨量和相关血清性激素水平的影响

目的 观察中等强度跑台运动对去卵巢大鼠骨量和相关血清性激素水平的影响,探讨其预防绝经后骨质疏松发生的作用机制.方法 40只未经产雌性SD大鼠,按体重随机分为假手术、去卵巢静止、去卵巢运动和雌激素4组.去卵巢运动组每周进行4次45 min、速度18 m/min,坡度5°的跑台训练;雌激素组每周颈部皮下注射3次17β-雌二醇,每次50 μg/kg体重.结束后,称量腹腔内脂肪和子宫重量;测定血清雌激素(E_2)、孕酮(P_4) 和睾酮(T)含量;检测右侧游离股骨和胫骨的骨密度(BMD)和骨矿物(BMC) 含量.结果 中等强度跑台运动能显著增加去卵巢大鼠股骨近端、中段和远端以及胫骨近端的BMC、BMD以及血清E_2水平,显著降低去卵巢大鼠腹腔内脂肪重量以及血清P4和T水平.结论 中等强度跑台运动抗去卵巢大鼠骨量下降的效应至少部分可能与其对血清性激素水平的调节有关.     

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.