Exercise Increases and Browns Muscle Lipid in High-Fat Diet-Fed Mice

Muscle lipid increases with high-fat feeding and diabetes. In trained athletes, increased muscle lipid is not associated with insulin resistance, a phenomenon known as the athlete's paradox. To understand if exercise altered the phenotype of muscle lipid, female C57BL/6 mice fed CTL or high-fat diet (HFD for 6 or 18 weeks) were further divided into sedentary or exercising groups (CTL-E or HFD-E) with voluntary access to running wheels for the last 6 weeks of experiments, running 6 h/night. Diet did not affect running time or distance. HFD mice weighed more than CTL after 18 weeks (p < 0.01). Quadriceps muscle TG was increased in running animals and in sedentary mice fed HFD for 18 weeks (p < 0.05). In exercised animals, markers of fat, Plin1, aP2, FSP27, and Fasn, were increased significantly in HFD groups. Ucp1 and Pgc1a, markers for brown fat, increased with exercise in the setting of high fat feeding. Fndc5, which encodes irisin, and CytC were sensitive to exercise regardless of diet. Plin5 was increased with HFD and unaffected by exercise; the respiratory exchange ratio was 15% lower in the 18-week HFD group compared with CTL (p < 0.001) and 10% lower in 18 weeks HFD-E compared with CTL-E (p < 0.001). Increased Ucp1 and Pgc1a in exercised muscle of running mice suggests that a beige/brown fat phenotype develops, which differs from the fat phenotype that induces insulin resistance in high fat feeding. This suggests that increased muscle lipid may develop a "brown" phenotype in the setting of endurance exercise training, a shift that is further promoted by HFD.

Exercise Regulation of Marrow Fat in the Setting of PPARγ Agonist Treatment in Female C57BL/6 Mice

The contribution of marrow adipose tissue (MAT) to skeletal fragility is poorly understood. Peroxisome proliferator-activated receptor (PPAR)γ agonists, associated with increased fractures in diabetic patients, increase MAT. Here, we asked whether exercise could limit the MAT accrual and increase bone formation in the setting of PPARγ agonist treatment. Eight-week-old female C57BL/6 mice were treated with 20-mg/kg · d rosiglitazone (Rosi) and compared with control (CTL) animals. Exercise groups ran 12 km/d when provided access to running wheels (CTL exercise [CTL-E], Rosi-E). After 6 weeks, femoral MAT (volume of lipid binder osmium) and tibial bone morphology were assessed by microcomputer tomography. Rosi was associated with 40% higher femur MAT volume compared with CTL (P < .0001). Exercise suppressed MAT volume by half in CTL-E mice compared with CTL (P < .01) and 19% in Rosi-E compared with Rosi (P < .0001). Rosi treatment increased fat markers perilipin and fatty acid synthase mRNA by 4-fold (P < .01). Exercise was associated with increased uncoupling protein 1 mRNA expression in both CTL-E and Rosi-E groups (P < .05), suggestive of increased brown fat. Rosi increased cortical porosity (P < .0001) but did not significantly impact trabecular or cortical bone quantity. Importantly, exercise induction of trabecular bone volume was not prevented by Rosi (CTL-E 21% > CTL, P < .05; Rosi-E 26% > Rosi, P < .01). In summary, despite the Rosi induction of MAT extending well into the femoral diaphysis, exercise was able to significantly suppress MAT volume and induce bone formation. Our results suggest that the impact of PPARγ agonists on bone and marrow health can be partially mitigated by exercise.

Acute small intestinal obstruction-an unusual complication of capsule endoscopy

We report a case of endoscopic capsule impaction causing acute small intestinal obstruction in a patient with Crohn's disease (CD), having obscure gastrointestinal bleeding. A 57-year old female presented with features of acute small bowel obstruction 2 days after capsule endoscopy elsewhere for the evaluation of intermittent bleeding per rectum and iron deficiency anemia. Patient underwent an exploratory laparotomy with right hemicolectomy for the diseased ileocecal region which mimicked malignancy. The capsule was found to be impacted in the strictured lumen of the terminal ileum. Post operative histopathological examination revealed it to be Crohn's disease.

Correlation of platelet count and acute ST-elevation myocardial infarction

The study was conducted in the Department of cardiology, NICVD Dhaka during the period January 2006 to December 2007 to assess the impact of platelet on ST-elevation myocardial infarction (STEMI). To perform this prospective study 200 patients with STEMI within 72 hours of chest pain of both sexes were randomly selected and were evaluated by clinical history, physical examination and with the help of ECG, Echocardiography and others cardiac risk factors analysis. Heparin therapy before admission, previously documented thrombocytopenia (<140,000/cmm), history of previous or current haemostatic disorder, renal impairment (Creatinine >1.6mg/dl) and history of PCI & CABG were excluded in this study. Patient of Platelet count (PC) ≤200000/cubic millimeter (cmm) in Group I and patient of Group II, platelet counts were PC >200000/cmm. Follow up period was 3 days to 7 days after hospital admission. Primary outcome heart failure (any Killip class) was significantly more in Group II than Group I (40.0% vs. 23.0%; p=0.009). Though the incidence of Killip class I and cardiogenic shock were not significant between these two groups but Killip class II (18.0% vs. 8.0%; p=0.036) and Killip class III (15.0% vs. 6.0%; p=0.037) heart failure were significantly more among the patient with higher platelet counts. In-hospital mortality, one of the primary outcomes of this study, was significantly higher in Group II (13.0%) than Group I (5.0 %) and p value was 0.048. Re-infarction was more in patient with higher platelet counts group (Group II) than patients with lower platelet count (Group I) but statistically was not significant (16.0% vs.11.0%; p=0.300).

Mechanically activated Fyn utilizes mTORC2 to regulate RhoA and adipogenesis in mesenchymal stem cells

Mechanical strain provides an anti-adipogenic, pro-osteogenic stimulus to mesenchymal stem cells (MSC) through generating intracellular signals and via cytoskeletal restructuring. Recently, mTORC2 has been shown to be a novel mechanical target critical for the anti-adipogenic signal leading to preservation of β-catenin. As mechanical activation of mTORC2 requires focal adhesions (FAs), we asked whether proximal signaling involved Src and FAK, which are early responders to integrin-FA engagement. Application of mechanical strain to marrow-derived MSCs was unable to activate mTORC2 when Src family kinases were inhibited. Fyn, but not Src, was specifically required for mechanical activation of mTORC2 and was recruited to FAs after strain. Activation of mTORC2 was further diminished following FAK inhibition, and as FAK phosphorylation (Tyr-397) required Fyn activity, provided evidence of Fyn/FAK cooperativity. Inhibition of Fyn also prevented mechanical activation of RhoA as well as mechanically induced actin stress fiber formation. We thus asked whether RhoA activation by strain was dependent on mTORC2 downstream of Fyn. Inhibition of mTORC2 or its downstream substrate, Akt, both prevented mechanical RhoA activation, indicating that Fyn/FAK affects cytoskeletal structure via mTORC2. We then sought to ascertain whether this Fyn-initiated signal pathway modulated MSC lineage decisions. siRNA knockdown of Fyn, but not Src, led to rapid attainment of adipogenic phenotype with significant increases in adipocyte protein 2, peroxisome proliferator-activated receptor gamma, adiponectin, and perilipin. As such, Fyn expression in mdMSCs contributes to basal cytoskeletal architecture and, when associated with FAs, functions as a proximal mechanical effector for environmental signals that influence MSC lineage allocation.

Bone marrow fat accumulation accelerated by high fat diet is suppressed by exercise

Marrow adipose tissue (MAT), associated with skeletal fragility and hematologic insufficiency, remains poorly understood and difficult to quantify. We tested the response of MAT to high fat diet (HFD) and exercise using a novel volumetric analysis, and compared it to measures of bone quantity. We hypothesized that HFD would increase MAT and diminish bone quantity, while exercise would slow MAT acquisition and promote bone formation. Eight week-old female C57BL/6 mice were fed a regular (RD) or HFD, and exercise groups were provided voluntary access to running wheels (RD-E, HFD-E). Femoral MAT was assessed by μCT (lipid binder osmium) using a semi-automated approach employing rigid co-alignment, regional bone masks and was normalized for total femoral volume (TV) of the bone compartment. MAT was 2.6-fold higher in HFD relative to RD mice. Exercise suppressed MAT in RD-E mice by more than half compared with RD. Running similarly inhibited MAT acquisition in HFD mice. Exercise significantly increased bone quantity in both diet groups. Thus, HFD caused significant accumulation of MAT; importantly running exercise limited MAT acquisition while promoting bone formation during both diets. That MAT is exquisitely responsive to diet and exercise, and its regulation by exercise appears to be inversely proportional to effects on exercise induced bone formation, is relevant for an aging and sedentary population.

Zirconium-titanium-phosphate nanoparticles: Triton X-100 based size modification, characterization and application in radiochemical separation

Zirconium-titanium-phosphate nanoparticles (ZTP) of different sizes were synthesized using tritron X-100 (polyethylene glycol-p-isooctylphenyl ether) surfactant. The materials were characterized by FTIR and powdered X-ray diffraction (XRD). The structural and morphological details of the material were obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM study was followed by energy dispersive spectroscopic analysis (EDS) for elemental analysis of the sample. The important peaks of the XRD spectra were analyzed to determine the probable composition of the material. The particle sizes were determined by dynamic light scattering (DLS) method. Ion exchange capacity was measured for different metal ions with sizes of the ZTP nanoparticles and size-dependent ion exchange property of the material was investigated thoroughly. The nanomaterial of the smallest size of around 5 nm was employed to separate carrier-free 137mBa from 137Cs in column chromatographic technique using 1.0 M HNO3 as eluting agent at pH = 5.

mTORC2 regulates mechanically induced cytoskeletal reorganization and lineage selection in marrow-derived mesenchymal stem cells

The cell cytoskeleton interprets and responds to physical cues from the microenvironment. Applying mechanical force to mesenchymal stem cells induces formation of a stiffer cytoskeleton, which biases against adipogenic differentiation and toward osteoblastogenesis. mTORC2, the mTOR complex defined by its binding partner rictor, is implicated in resting cytoskeletal architecture and is activated by mechanical force. We asked if mTORC2 played a role in mechanical adaptation of the cytoskeleton. We found that during bi-axial strain-induced cytoskeletal restructuring, mTORC2 and Akt colocalize with newly assembled focal adhesions (FA). Disrupting the function of mTORC2, or that of its downstream substrate Akt, prevented mechanically induced F-actin stress fiber development. mTORC2 becomes associated with vinculin during strain, and knockdown of vinculin prevents mTORC2 activation. In contrast, mTORC2 is not recruited to the FA complex during its activation by insulin, nor does insulin alter cytoskeletal structure. Further, when rictor was knocked down, the ability of mesenchymal stem cells (MSC) to enter the osteoblastic lineage was reduced, and when cultured in adipogenic medium, rictor-deficient MSC showed accelerated adipogenesis. This indicated that cytoskeletal remodeling promotes osteogenesis over adipogenesis. In sum, our data show that mTORC2 is involved in stem cell responses to biophysical stimuli, regulating both signaling and cytoskeletal reorganization. As such, mechanical activation of mTORC2 signaling participates in mesenchymal stem cell lineage selection, preventing adipogenesis by preserving β-catenin and stimulating osteogenesis by generating a stiffer cytoskeleton.

Behcet disease and pregnancy

PURPOSE

Behcet disease (BD) is a multisystemic vaculitis commonly diagnosed in reproductive years. The authors aimed to investigate the relationship between BD and pregnancy outcomes.

MATERIALS AND METHODS

In this multicenter retrospective survey study, the authors compared the pregnancy outcomes of BD patients with the healthy controls.

RESULTS

A total of 298 pregnancies of 94 patients with BD and 219 pregnancies of 95 healthy controls were evaluated. The mean birth weight of all babies of women with BD and the control group were 3,214 grams and 3,351 grams, respectively (p = 0.028). The miscarriage rates were also higher in the BD group. The com- plication rates of pregnancy with hypertension, preeclampsia, preterm labour in the study group and the control group were 12.8% and 11.6%, respectively (p = 0.489).

CONCLUSION

The current study demonstrated that BD patients delivered smaller babies and they have higher miscarriage rates when compared to the healthy controls which might be due to the vasculitis of the placenta.

Mechanical input restrains PPARγ2 expression and action to preserve mesenchymal stem cell multipotentiality

Exercise-generated signals are pro-osteogenic and anti-adipogenic within the marrow. In vitro studies indicate that mechanical signals directly block adipogenic differentiation through activation of β-catenin and by limiting PPARγ2 expression. Whether mechanically generated β-catenin can inhibit adipogenesis during PPARγ transactivation is unknown. We evaluated the ability of mechanical signals to limit adipogenesis in marrow derived mesenchymal stem cells (mdMSC) distal to activation of PPARγ. First, we established that mdMSC attained an adipogenic phenotype within 2-4 days in the presence of rosiglitazone (1-25 μM) and that β-catenin activation via GSK3β inhibition interfered with this process. Similarly, mechanical strain (3600 cycles, 2% strain daily) inhibited adipogenesis at 3 days, preventing rosiglitazone-induced PPARγ upregulation as well as aP2 and adiponectin protein expression. To assess whether a reduction in PPARγ expression was necessary for anti-adipogenic action, PPARγ2 was overexpressed: both mechanical strain and GSK3β inhibition prevented expression of aP2 and adiponectin proteins despite abundant PPARγ2 and its ligand. To understand the fate of single cells experiencing mechanical strain we generated mdMSC from aP2-GFP reporter expressing mice. Rosiglitazone treatment for 3 days induced GFP expression in more than 80% of cells. Sorting by GFP expression revealed that the highest 20% of aP2-GFP expressing cells was responsible for the majority of adipogenic protein expression. This highly expressing GFP fraction had a reduced ability to respond to an osteogenic stimulus: BMP-2 treatment increased osterix by 12-fold in contrast to the 42-fold increase in osterix expression that resulted from BMP-2 treatment of the bottom 75% of GFP expressing cells. This suggested that highly expressing aP2-GFP cells represented more terminally differentiated adipocytes, with reduced multipotentiality. Application of mechanical strain to aP2-GFP mdMSC treated with rosiglitazone caused a two-fold decrease in the size of the upper cell fraction, suggesting that mechanical strain preserved MSC in a multipotent state. Our data show that mechanical strain restricts adipogenesis both by limiting PPARγ2 expression and by preventing PPARγ action, protecting the potential of MSC to enter other lineages.

Mechanical strain downregulates C/EBPβ in MSC and decreases endoplasmic reticulum stress

Exercise prevents marrow mesenchymal stem cell (MSC) adipogenesis, reversing trends that accompany aging and osteoporosis. Mechanical input, the in-vitro analogue to exercise, limits PPARγ expression and adipogenesis in MSC. We considered whether C/EBPβ might be mechanoresponsive as it is upstream to PPARγ, and also is known to upregulate endoplasmic reticulum (ER) stress. MSC (C3H10T1/2 pluripotent cells as well as mouse marrow-derived MSC) were cultured in adipogenic media and a daily mechanical strain regimen was applied. We demonstrate herein that mechanical strain represses C/EBPβ mRNA (0.6-fold ±0.07, p<0.05) and protein (0.4-fold ±0.1, p<0.01) in MSC. SiRNA silencing of β-catenin prevented mechanical repression of C/EBPβ. C/EBPβ overexpression did not override strain's inhibition of adipogenesis, which suggests that mechanical control of C/EBPβ is not the primary site at which adipogenesis is regulated. Mechanical inhibition of C/EBPβ, however, might be critical for further processes that regulate MSC health. Indeed, overexpression of C/EBPβ in MSC induced ER stress evidenced by a dose-dependent increase in the pro-apoptotic CHOP (protein 4-fold ±0.5, p<0.05) and a threshold reduction in the chaperone BiP (protein 0.6-fold ±0.1, p = 0.2; mRNA 0.3-fold ±0.1, p<0.01). ChIP-seq demonstrated a significant association between C/EBPβ and both CHOP and BiP genes. The strain regimen, in addition to decreasing C/EBPβ mRNA (0.5-fold ±0.09, p<0.05), expanded ER capacity as measured by an increase in BiP mRNA (2-fold ±0.2, p<0.05) and protein. Finally, ER stress induced by tunicamycin was ameliorated by mechanical strain as demonstrated by decreased C/EBPβ, increased BiP and decreased CHOP protein expression. Thus, C/EBPβ is a mechanically responsive transcription factor and its repression should counter increases in marrow fat as well as improve skeletal resistance to ER stress.

Thyroid hormone status in apparently healthy elderly persons

Thyroid disorders are frequent in elderly population and difficult to recognize because of their atypical presentation, and the absence of classic signs and symptoms. Nonspecific symptoms, even in the absence of thyroid dysfunction, are common in this age group, including fatigue, anorexia, weight loss, failure to rehabilitate, and difficult to concentrate. Symptoms of aging can be confused easily with hypothyroidism. The interpretation of thyroid function tests is also cumbersome in aged individuals because of the difficulty in differentiating physiologic age-associated changes from alterations secondary to acute or chronic non-thyroidal illness. In the present study, a total 100 subjects were included. Subjects were divided into two groups: Group I - Control (n=50) and Group II - Case (n=50). Fifty apparently healthy young adults were taken as control (Group I) and 50 apparently healthy elderly subjects were included in case (Group II). Group I was subdivided into two groups- Group IA: young male (n=25) and Group IB: young female (n=25). Group II was also subdivided into two groups - Group IIA: elderly male (n=25) and Group IIB: elderly female (n=25). All the subjects were selected from the local community of Mymensingh Sadar, Mymensingh Medical College, Mymensingh and Community Based Medical College, Bangladesh, Mymensingh. In the present study, the difference of mean serum T3 concentration between Group I (control) and Group II (elderly subjects) was not found to be significant (p>0.05). Significant difference in serum TSH concentration between Group IA and Group IIA was to be found (p<0.001). The difference of mean serum T4 concentration between Group IB and Group IIB was not found significant (p>0.05). Significant difference in mean serum TSH concentration between Group IB and Group IIB was to be found (p<0.001).

Mechanically induced focal adhesion assembly amplifies anti-adipogenic pathways in mesenchymal stem cells

The fate of pluripotent mesenchymal stem cells (MSC) is determined through integration of chemical, spatial, and physical signals. The suppression of MSC adipogenesis by mechanical stimuli, which requires Akt-induced inhibition of glycogen synthase kinase 3β (GSK3β) with β-catenin activation, can be enhanced by repetitive dosing within a single day. Here, we demonstrate that reapplication of cyclic strain within a 24-hour period leads to amplification of both Akt activation and its subsequent inhibition of GSK3β, such that total cycle number can be reduced while still inhibiting adipogenesis. Amplification of Akt signaling is facilitated by a dynamic restructuring of the cell in response to mechanical signals, as evidenced by a transient increase in focal adhesion (FA) number and increased RhoA activity. Preventing FA assembly or development of tension blocks activation of Akt by mechanical signals, but not by insulin. This indicates that the FA infrastructure is essential to the physical, but not necessarily the chemical, sensitivity, and responsiveness of the cell. Exploiting the transient nature of cytoskeletal remodeling may represent a process to enhance cell responsiveness to mechanical input and ultimately define the fate of MSCs with a minimal input.

Threshold estimation based on a p-value framework in dose-response and regression settings

We use p-values to identify the threshold level at which a regression function leaves its baseline value, a problem motivated by applications in toxicological and pharmacological dose-response studies and environmental statistics. We study the problem in two sampling settings: one where multiple responses can be obtained at a number of different covariate levels, and the other the standard regression setting involving limited number of response values at each covariate. Our procedure involves testing the hypothesis that the regression function is at its baseline at each covariate value and then computing the potentially approximate p-value of the test. An estimate of the threshold is obtained by fitting a piecewise constant function with a single jump discontinuity, known as a stump, to these observed p-values, as they behave in markedly different ways on the two sides of the threshold. The estimate is shown to be consistent and its finite sample properties are studied through simulations. Our approach is computationally simple and extends to the estimation of the baseline value of the regression function, heteroscedastic errors and to time series. It is illustrated on some real data applications.

Mechanical regulation of glycogen synthase kinase 3β (GSK3β) in mesenchymal stem cells is dependent on Akt protein serine 473 phosphorylation via mTORC2 protein

Mechanical signals can inactivate glycogen synthase kinase 3β (GSK3β), resulting in stabilization of β-catenin. This signaling cascade is necessary for the inhibition of adipogenesis in mesenchymal stem cells (MSC) that is produced by a daily strain regimen. We investigated whether Akt is the mechanically activated kinase responsible for phosphorylation and inactivation of GSK3β in MSC. Mechanical strain (2% magnitude, 0.17 Hz) induced phosphorylation of Akt at Ser-473 and Thr-308 in parallel with phosphorylation of GSK3β at Ser-9. Inhibiting Akt (Akt1/2 kinase inhibitor treatment or Akt knockdown) prevented strain-induced phosphorylation of GSK3β at Ser-9. Inhibition of PI3K prevented Thr-308 phosphorylation, but strain-induced Ser-473 phosphorylation was measurable and induced phosphorylation of GSK3β, suggesting that Ser-473 phosphorylation is sufficient for the downstream mechanoresponse. As Rictor/mTORC2 (mammalian target of rapamycin complex 2) is known to transduce phosphorylation of Akt at Ser-473 by insulin, we investigated whether it contributes to strain-induced Ser-473 phosphorylation. Phosphorylation of Ser-473 by both mechanical and insulin treatment in MSC was prevented by the mTOR inhibitor KU0063794. When mTORC2 was blocked, mechanical GSK3β inactivation was prevented, whereas insulin inhibition of GSK3β was still measured in the absence of Ser-473 phosphorylation, presumably through phosphorylation of Akt at Thr-308. In sum, mechanical input initiates a signaling cascade that is uniquely dependent on mTORC2 activation and phosphorylation of Akt at Ser-473, an effect sufficient to cause inactivation of GSK3β. Thus, mechanical regulation of GSK3β downstream of Akt is dependent on phosphorylation of Akt at Ser-473 in a manner distinct from that of growth factors. As such, Akt reveals itself to be a pleiotropic signaling molecule whose downstream targets are differentially regulated depending upon the nature of the activating input.