Efficient Dielectrophoretic Patterning of Embryonic Stem Cells in Energy Landscapes Defined by Hydrogel Geometries

In this study, we have developed an integrated microfluidic platform for actively patterning mammalian cells, where poly(ethylene glycol) (PEG) hydrogels play two important roles as a non-fouling layer and a dielectric structure. The developed system has an embedded array of PEG microwells fabricated on a planar indium tin oxide (ITO) electrode. Due to its dielectric properties, the PEG microwells define electrical energy landscapes, effectively forming positive dielectrophoresis (DEP) traps in a low-conductivity environment. Distribution of DEP forces on a model cell was first estimated by computationally solving quasi-electrostatic Maxwell’s equations, followed by an experimental demonstration of cell and particle patterning without an external flow. Furthermore, efficient patterning of mouse embryonic stem (mES) cells was successfully achieved in combination with an external flow. With a seeding density of 10⁷ cells/mL and a flow rate of 3 μL/min, trapping of cells in the microwells was completed in tens of seconds after initiation of the DEP operation. Captured cells subsequently formed viable and homogeneous monolayer patterns. This simple approach could provide an efficient strategy for fabricating various cell microarrays for applications such as cell-based biosensors, drug discovery, and cell microenvironment studies.     

A Novel Heterophilic Antibody Interaction Involves IgG4

IgG4 has been implicated in a diverse set of complex pathologies – e.g. autoimmune pancreatitis (AIP), idiopathic membranous nephropathy – and carries unique features including lack of activation of the classical complement pathway and a dynamic Fab‐arm exchange. We recently showed that the rheumatoid factor (RF)‐like activity of IgG4 is achieved through a hitherto unknown, Fc–Fc (and not Fab–Fc as is the case in classical RF; CRF) interaction; hence the name, novel RF (NRF). Here, we further explore the resemblance/difference between CRF and NRF. As heterophilic interactions of human IgM RF (CRF) are well known, we checked whether this is the case for IgG4. Human IgG4 showed variable reactivity to animal IgGs: reacting intensely with rabbit and mouse IgGs, but weakly with others. The binding to rabbit IgG was not through the Fab (as in CRF) but via the Fc piece, as was recently shown for human IgG (NRF). This binding correlates with the IgG4 concentration per se and could therefore be of diagnostic usage and incidentally explain some observed interferences in biological assays. In conclusion, here is defined a novel heterophilic antibody interaction and is established the universality of the unique Fc–Fc binding, both involving IgG4.     

Triple non-invasive diagnostic test for exclusion of common bile ducts stones before laparoscopic cholecystectomy

AIM： To evaluate the impact of a preoperative ＂triple non-invasive diagnostic test＂ for diagnosis and/or exclusion of common bile duct stones. METHODS： All patients with symptomatic gallstone disease, operated on by laparoscopic cholecystectomy from March 2004 to March 2006 were studied retrospectively. Two hundred patients were included and reviewed by using a triple diagnostic test including： patient＇s medical history, routine liver function tests and routine ultrasonography. All patients were followed up 2-24 mo after surgery to evaluate the impact of triple diagnostic test. RESULTS： Twenty-five patients were identified to have common bile duct stones. Lack of history of stones, negative laboratory tests and normal ultrasonography alone was proven to exclude common bile duct stones in some patients. However, a combination of these three components （triple diagnostic）, was proven to be the most statistically significant test to exclude common bile duct stones in patients with gallstone disease. CONCLUSION： Using a combination of routinely used diagnostic components as triple diagnostic modality would increase the diagnostic accuracy of common bile duct stones preoperatively. This triple non-invasive test is recommended for excluding common bile duct stones and to identify patients in need for other investigations.     

Preconditioning with oxygen attenuates rat renal ischemia-reperfusion injury

BACKGROUND: Short time pretreatment with oxygen is reported to be protective against subsequent ischemia-reperfusion (IR) injury of heart and spinal cord in some animal models. The purpose of this study was to investigate the effects of pre-exposure to hyperoxic environment on rat renal IR injury for the first time. MATERIALS AND METHODS: The effects of 1 h/d pretreatment with oxygen (>or=95%) for 5 days on a right nephrectomized rat model of renal IR injury was investigated by comparing creatinine clearance, fractional excretion of sodium, plasma creatinine, blood urea nitrogen, and histological injury scores among three groups: IR (40 min ischemia-24 h reperfusion), sham (no IR), and hyperoxia (5 days intermittent pretreatment with oxygen + IR). RESULTS: Intermittent pretreatment with oxygen resulted in significant improvement of creatine clearance and fractional excretion of sodium (P 相似文献   

The effects of fructo-oligosaccharides in combination with soy protein on bone in osteopenic ovariectomized rats

OBJECTIVE: The intestinal microflora is important in rendering soy isoflavones bioavailable by facilitating their conversion to equol. Hence, substances that can modulate the intestinal microflora could affect the bioavailability of isoflavones. In this study, we examined the effects of fructo-oligosaccharides (FOS), a prebiotic, on enhancing the effects of soy isoflavones on bone in ovariectomized osteopenic female rats. DESIGN: Sixty-three 9-month-old female Sprague-Dawley rats were either sham-operated (Sham; one group) or ovariectomized (Ovx; four groups) and were fed a control diet for 3 months to induce bone loss. After bone loss was confirmed via dual-energy x-ray absorptiometry, rats were placed on dietary treatment for 4 months. The Sham and one Ovx group received a control diet, and the remaining Ovx groups received either a soy protein-based diet (Soy), a FOS-supplemented diet (FOS), or a soy protein-based and FOS-supplemented diet (Soy+FOS). Before the termination of the study, whole-body bone mineral density (BMD) and bone mineral content (BMC) were assessed under anesthesia. Immediately after euthanasia, bone specimens were collected for the assessments of BMD, BMC, and biomechanical and microarchitectural properties. RESULTS: Whole-body BMD values were significantly higher in FOS and Soy+FOS groups compared with Ovx controls. The tibial BMC increased by 10%, 6%, and 4% in Soy, FOS, and Soy+FOS groups, respectively, compared to the Ovx control group. FOS and FOS+Soy treatments had the most pronounced effects in enhancing lumbar BMC and BMD. The FOS+Soy combination effectively improved tibial microarchitectural properties by enhancing trabecular number and lowering trabecular separation compared with Ovx controls. The effects of dietary treatments on lumbar microarchitectural properties were minimal and biomechanical properties of the femur were not affected by any of the dietary treatments. CONCLUSION: Our findings suggest that, although incorporation of either soy or FOS in the diet of Ovx rats can improve BMD of the whole body, tibiae, and lumbar vertebrae, their combination had no any additive effects. However, in terms of microarchitecture, the combination of soy and FOS had a greater effect in reversing the loss of certain microarchitectural parameters such as tibial trabecular number, separation, and thickness.     

Genetics of type 2 diabetes mellitus and obesity--a review

Type 2 diabetes (T2D) and obesity are recognized as conditions of growing biomedical importance to societies worldwide. Despite this, lack of understanding concerning the processes which normally serve to maintain weight and to regulate glucose concentrations, and ignorance about the mechanisms by which these homeostatic processes fail, remains a significant obstacle to the development of improved tools for management and prevention. There has been a long-standing belief that the identification of the specific genes influencing development of these conditions has the potential to reveal these fundamental processes, thereby providing vital clues to support clinical advances. Furthermore, there has been the hope that this information will translate into the capacity to deliver more 'personalized' medical care, whereby management can be tailored in accordance with an appreciation of individual molecular pathogenesis. As this review indicates, these developments are already a reality for selected monogenic forms of diabetes and obesity. Recent advances in the identification of genes underlying multifactorial forms of these conditions will accelerate efforts to effect similar clinical translation across the full spectrum of disease.     

The prevalence of distal junctional kyphosis following posterior instrumentation and arthrodesis for adolescent idiopathic scoliosis

Distal junctional kyphosis (DJK) is a radiographic finding in patients that undergo spinal instrumentation and fusion, since there is an abrupt transition between fixed and mobile spinal segments.The true incidence of DJK is variable in literature and seems that has a multifactorial etiology. A consecutive series of 130 patients (mean age 15.6 years) with adolescent idiopathic scoliosis who underwent posterior spinal fusion and instrumentation were evaluated by analyzing coronal and sagittal angulation and balance measurements from standing radiographs obtained pre-operatively, within 6 weeks post-operation, at two years postoperative and at the latest follow-up. There was 35 male and 95 female. The mean time of follow-up was 36 months. The incidence of DJK at latest follow-up was 6.9% (9 patients). In DJK group, distal junctional angle from pre-operative of -12.5° lordosis (-30 to 0) reached to -5.5° (P=0.015) at 6 weeks postoperation and to -1.4° (-20 to 12°) (P=0.000) at 2 years follow-up,with mean of 12.1° kyphotic change (10-20°). In non DJK group, distal junctional angle from pre-operative angle of -7.5° reached -8.1° at 2 years follow-up (P=0.43). The mean age of DJK group at surgery was 17 years and for non-DJK group was 15.4 years (P=0.022). Distal junctional kyphosis was less common in this study than previous reports and stabilized after two years. The magnitude of coronal cobb angles or multiplicity of coronal curves had no effect in developing DJK that may be prevented by incorporation of the first lordotic disc into the fusion construct.     

Possible involvement of PPAR-gamma receptor and nitric oxide pathway in the anticonvulsant effect of acute pioglitazone on pentylenetetrazole-induced seizures in mice

Besides the receptor-mediated effects of pioglitazone, the involvement of nitric oxide (NO) has been previously demonstrated in some pioglitazone-induced central and peripheral effects. In the present study, the effects of acutely administered pioglitazone on pentylenetetrazole (PTZ)-induced seizures and involvement of NO were evaluated in mice. To determine the threshold for clonic seizures, PTZ was administered intravenously. A single dose of pioglitazone (10, 20, 40 and 80 mg/kg, p.o.) was administered either 2 or 4h prior to induction of seizures. For determination of possible role of peroxisome proliferator activated receptor gamma (PPAR-γ) and nitric oxide pathway in this effect, the effects of a PPAR-γ antagonist, GW9662 (2 mg/kg); a non-specific nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME; 0.3, 1, 3, and 10 mg/kg); a specific iNOS inhibitor, aminoguanidine (100mg/kg, i.p.) or a nitric oxide precursor, L-arginine (30, 60, 100 and 200mg/kg, i.p.); each administered 15 min prior to pioglitazone, were investigated on the anticonvulsant effect of this drug. Administration of pioglitazone (40 and 80 mg/kg) increased the threshold of PTZ-induced seizure in a dose-dependent, and time-dependent manner. GW9662 reversed the anticonvulsant effect of pioglitazone (40 mg/kg). Acute administration of L-NAME (1, 3 and 10mg/kg) inhibited the anticonvulsant effect of pioglitazone (40 mg/kg), the same result was detected with aminoguanidine (100mg/kg); whereas L-arginine, in the noneffective dose (100mg/kg), potentiated the seizure threshold when co-administered with a subeffective dose of pioglitazone (20mg/kg). CONCLUSION: The present study demonstrates the anticonvulsant effect of acute pioglitazone on PTZ-induced seizures in mice. This effect was reversed by PPAR-γ antagonist, and both a specific- and a non-specific nitric oxide synthase inhibitors, and augmented by nitric oxide precursor, L-arginine. These results support that the anticonvulsant effect of pioglitazone is mediated through PPAR-γ receptor-mediated pathway and also, at least partly, through the nitric oxide pathway.