Mathematical Models of the Metabolic System in Health and in Diabetes: GIM, Simulation Software of Meal Glucose�CInsulin Model

Background

A simulation model of the glucose–insulin system in normal life conditions can be very useful in diabetes research, e.g., testing insulin infusion algorithms and decision support systems and assessing glucose sensor performance and patient and student training. A new meal simulation model has been proposed that incorporates state-of-the-art quantitative knowledge on glucose metabolism and its control by insulin at both organ/tissue and whole-body levels. This article presents the interactive simulation software GIM (glucose insulin model), which implements this model.

Methods

The model is implemented in MATLAB, version 7.0.1, and is designed with a windows interface that allows the user to easily simulate a 24-hour daily life of a normal, type 2, or type 1 diabetic subject. A Simulink version is also available. Three meals a day are considered. Both open- and closed-loop controls are available for simulating a type 1 diabetic subject.

Results

Software options are described in detail. Case studies are presented to illustrate the potential of the software, e.g., compare a normal subject vs an insulin-resistant subject or open-loop vs closed-loop insulin infusion in type 1 diabetes treatment.

Conclusions

User-friendly software that implements a state-of-the-art physiological model of the glucose–insulin system during a meal has been presented. The GIM graphical interface makes its use extremely easy for investigators without specific expertise in modeling.     

Scatter correction based on an artificial neural network for99mTc and123I dual-isotope SPECT in myocardial and brain imaging

The aim of this study was to elucidate the clinical usefulness of scatter correction with an artificial neural network (ANN) in 99mTc and 123I dual-isotope SPECT. METHODS: Two algorithms for ANN scatter correction were tested: ANN-10 and ANN-3 employing 10 and 3 energy windows for data acquisition, respectively. Three patients underwent myocardial or brain SPECT with one of the following combinations of radiopharmaceuticals administered: 99mTc-tetrofosmin and 123I-metaiodobenzylguanidine (MIBG), 99mTc-methoxyisobutylisonitrile (MIBI) and 123I-beta-methyl-paraiodophenyl-pentadecanoic acid (BMIPP), or 99mTc-ethyl-cistainate dimmer (ECD) and 123I-iomazenil. The patients were also referred for single-isotope imaging incorporating conventional triple-energy window (TEW) scatter correction. Crosstalk- and scatter-corrected 99mTc- and 123I-SPECT images in dual-isotope acquisition with ANN were compared with those in single-isotope acquisition. RESULTS: The ANN method well separated 123I and 99mTc primary photons. Although ANN-10 yielded images of poor quality, ANN-3 offered comparable image quality with the single-isotope scan without significant increase of acquisition time. CONCLUSION: The proposed method is clinically useful because it provides various combinations of information without anatomical misregistration with one acquisition.     

Biocompatibility of acellular human pericardium

BACKGROUND: Previous studies have shown successful decellularization of human pericardium without affecting the major structural components and strength of the matrix. The aim of this study was to assess the biocompatibility and reseeding potential of the acellular human pericardial scaffold. MATERIALS AND METHODS: Pericardia were treated sequentially with hypotonic buffer, sodium dodecyl sulfate, and a nuclease solution. The presence of cellular attachment factors after decellularization was evaluated using immunohistochemistry. The scaffold was seeded with dermal fibroblasts and cellular attachment to and numbers of cells penetrating were assessed over time. Biocompatibility was also evaluated following subcutaneous implantation into a mouse model for three months. RESULTS: After decellularization, the scaffold stained positively for fibronectin, but collagen IV and laminin staining was reduced. Seeded fibroblasts attached to the mesothelial surface and were visualized in the tissue within a week of seeding. The majority of fibroblasts in the tissue were viable and there was evidence of remodeling of the matrix. Analysis of the explanted tissues from mice showed that fresh/frozen and glutaraldehyde-fixed pericardia were encapsulated with a thick layer of inflammatory cells and fibrous tissue. In contrast, the decellularized scaffold was infiltrated with myofibroblasts, CD34+ cells and macrophages, indicating a healthy repair process. Compared with the glutaraldehyde-fixed tissue, the calcium content of the fresh/frozen and decellularized pericardia was negligible. CONCLUSIONS: The pericardial scaffold was biocompatible in vitro and in the mouse model in vivo.     

(−)Epigallocatechin-3-gallate inhibits the spontaneous firing of rat locus coeruleus neuron

(−)Epigallocatechin-3-gallate (EGCG), a tea catechin, has been known to cause many biological actions, such as anxiolytic and hypotensive effects in behavioral studies. However, to date, few reports investigate its neuronal modulation. In this study, intracellular recording was used to test the neuronal modulation of different catechins on locus coeruleus (LC) neuron, which has been demonstrated to be affected by cardiovascular function regulation and stressful events. Several catechins (1–1000 μM) were tested, including: (−)catechin (C), (−)catechingallate (CG), (−)epicatechin (EC), (−)epicatechin-3-gallate (ECG), (−)epigallocatechin (EGC) and EGCG. The results showed that catechins EC, ECG, EGC and EGCG could inhibit the spontaneous firing of the LC neurons; furthermore, these catechins show potency and efficacy in the order of EGCG > ECG > EC ≈ EGC. Among the tested catechins, EGCG was the most potent in inhibiting LC's spontaneous firing with IC₅₀ of 20.5 μM. This caused us to further examine the EGCG's desensitization and tolerance properties. When continuously administering EGCG at 1–300 μM for 20 min, no acute desensitization appeared. However, repeated applications of 300 μM EGCG at 5 min each time showed different results. The second and third applications induced less responses compared to that of the first application, suggesting a development of tolerance towards EGCG in inhibiting LC neuronal activity. Our data suggest that EGCG can inhibit LC neuron's spontaneous firing in a dose-dependent manner, with developed tolerance only when high concentration of EGCG is repeatedly applied.     

热压-盐析法制备骨组织工程支架的工艺及性能表征**☆

背景：热压-盐析法制备聚合物组织工程支架,设备简单,成型快速,力学强度较高,但是适当的支架成型条件及材料组分对支架的性能尤为重要。 目的：观察热压-盐析法制备聚乳酸/聚己内酯/纳米羟基磷灰石复合组织工程支架中温度、时间、压力以及羟基磷灰石的加入对支架性能的影响。 设计、时间及地点：复合材料性能测试,对比观察实验,于2008-09/2009-05在同济大学材料科学与工程学院纳米与生物高分子材料研究所完成。 材料：聚乳酸、聚己内酯、羟基磷灰石均为实验室合成。 方法：采用液相共沉淀法制备纳米羟基磷灰石,借助溶剂将聚乳酸、聚己内酯、纳米羟基磷灰石和致孔剂进行共混,去除溶剂后在一定温度、压力、时间下进行热压制得聚乳酸/聚己内酯/纳米羟基磷灰石复合组织工程支架。 主要观察指标：①X射线衍射分析、透射电镜观察羟基磷灰石的相结构、形状和尺寸。②扫描电镜观察复合多孔支架的形貌。③通过表面接触角观察不同材料的亲水性。④不同热压时间、温度、压力对支架孔隙率及抗压强度的影响。⑤不同含量羟基磷灰石对支架抗压强度的影响。 结果：热压-盐析法制备的聚乳酸/聚己内酯/纳米羟基磷灰石复合组织工程支架具有连通开孔的多孔结构,孔径多分布在300~340 µm,支架的表面无结皮现象,孔隙率和抗压强度均满足骨支架的应用要求;纳米羟基磷灰石的加入提高了支架的抗压强度,但支架亲水性随其质量分数的升高而下降,纳米羟基磷灰石质量分数为4%时支架的综合性能相对较好;热压温度、时间、压力对支架的性能影响较大,支架的综合性能在热压温度65 ℃、热压压力7 MPa、热压时间3 min条件时相对较好。 结论：热压-盐析法构建的骨组织工程支架孔径、孔隙率和抗压强度均满足应用要求;热压温度、时间、压力对支架的性能影响较大;纳米羟基磷灰石的加入提高了支架的抗压强度,但对支架亲水性有影响。 关键词：多孔支架;骨组织工程;热压-盐析法;纳米羟基磷灰石;支架性能     

一种四环素严紧控制的真核表达系统

目的构建一种严紧调控的表达系统,用于在真核细胞内表达外源性兴趣基因。方法融合四环素诱导元件、人工细菌染色体(BAC)以及Gateway技术,建立了一种新的表达体系。并且将该体系进行了测试。结果兴趣基因编码的β-catenin-ERα融合蛋白经荧光素酶活性检测和Western杂交分析,其表达被四环素或强力霉素严紧控制,在表达载体pE11-IGR-β-catenin-ERα中,EGFP的表达量恒定,可以作为流式细胞术有效的筛选标记。结论该系统可以作为一种有效的工具,用于在真核细胞中表达外源性兴趣基因,并且实现严紧的表达调控。     

永久性心脏起搏器植入77例临床分析

目的观察77例永久心脏起搏器植入的疗效及并发症。方法对77例永久心脏起搏器植入患者进行随访观察,对术中疗效及术后各种并发症进行分析。结果所有手术均成功完成,起搏模式：植入单腔起搏47例,房室双腔起搏28例,单腔心室埋藏式心脏复律除颤器1例,心脏再同步化起搏1例。术后囊袋血肿3例,电极脱位2例,起搏器囊袋渍破1例,起搏器综合征7例。结论采取相关措施,加强起搏器术后随访工作,可以减少并发症的发生。     

肋骨肋软骨折高频超声诊断价值

目的探讨超声诊断肋骨肋软骨折的价值。方法回顾性分析61例经高频超声诊断的肋骨肋软骨折,所有肋骨折病例超声检查前均经X线拍片检查,但仅2例显示出明显的骨折征象。结果 61例患者共查出肋骨折66处,肋软骨折13处。结论高频超声能清晰显示肋软骨折的部位、形态,并能动态观察骨折愈合的过程,是诊断肋骨肋软骨折的首选检查方法。     

纳米羟基磷灰石/壳聚糖支架材料复合大鼠成骨细胞培养的实验研究

目的 将纳米羟磷灰石/壳聚糖(nHA/CS)支架材料与大鼠的成骨细胞在体外复合培养,研究其生物相容性,以期在骨组织工程支架材料的选择方面提供依据.方法 原代培养大鼠成骨细胞,倒置显微镜作细胞形态学观察,碱性磷酸酶(ALP)染色和茜素红钙染色对细胞进行鉴定.将第三代细胞与nHA/CS材料体外复合培养,采用MTT比色法和...     

PRP对纳米HA/PLGA复合支架上鼠骨骼肌卫星细胞增殖和成骨活性的影响

目的:研究富血小板血浆(platelet-rich plasma,PRP)对纳米羟基磷灰石(nano-hydroxyapatite,nHA)/聚乳酸乙醇酸(poly lactic acid-co-glycolic acid,PLGA)(nHA/PLGA)支架上SD大鼠骨骼肌卫星细胞(muscle satellite cells,MSCs)黏附、增殖和成骨活性的影响。方法:将体外培养、扩增的鼠MSCs与同一供体来源的PRP混合,滴加到nHA/PLGA支架上,形成MSCs/PRP/nHA/PLGA复合物(实验组),继续在体外培养,以MSCs/nHA/PLGA复合物作为对照组。通过扫描电镜观察MSCs在支架上黏附、生长和增殖情况;水溶性四氮唑法(WST-1)法测定MSCs增殖情况;碘化丙啶(PI)与钙黄绿素-AM(Calcein-AM)检测MSCs的荧光活性;组织化学方法检测培养液中碱性磷酸酶(alkaline phosphatase,ALP)活性和骨钙素(osteocalcin,OC)含量;RT-PCR检测骨桥蛋白(osteopontin,OPN)mRNA的表达。结果:扫描电镜观察显示,实验组大量MSCs黏附在支架表面及其洞壁上,并大量增殖和分泌骨基质,而对照组复合材料表面细胞附着较少;WST-1测定实验组吸光度值明显大于对照组(P<0.05);PI荧光染色二组的死细胞数量均较少;实验组ALP活性和OC含量均较对照组增高明显(P<0.05);RT-PCR结果显示OPN在实验组中表达明显增强。结论:PRP促进了nHA/PLGA支架上鼠MSCs黏附、增殖和成骨分化。