Decline in mitochondrial bioenergetics and shift to ketogenic profile in brain during reproductive senescence

Background

We have previously demonstrated that mitochondrial bioenergetic deficits precede Alzheimer's pathology in the female triple transgenic Alzheimer's (3xTgAD) mouse model. Herein, we sought to determine the impact of reproductive senescence on mitochondrial function in the normal non-transgenic (nonTg) and 3xTgAD female mouse model of AD.

Methods

Both nonTg and 3xTgAD female mice at 3, 6, 9, and 12 months of age were sacrificed and mitochondrial bioenergetic profile as well as oxidative stress markers were analyzed.

Results

In both nonTg and 3xTgAD mice, reproductive senescence paralleled a significant decline in PDH, and Complex IV cytochrome c oxidase activity and mitochondrial respiration. During the reproductive senescence transition, both nonTg and 3xTgAD mice exhibited greater individual variability in bioenergetic parameters suggestive of divergent bioenergetic phenotypes. Following transition through reproductive senescence, enzymes required for long-chain fatty acid (HADHA) and ketone body (SCOT) metabolism were significantly increased and variability in cytochrome c oxidase (Complex IV) collapsed to cluster at a ∼ 40% decline in both the nonTg and 3xTgAD brain which was indicative of alternative fuel generation with concomitant decline in ATP generation.

Conclusions

These data indicate that reproductive senescence in the normal nonTg female brain parallels the shift to ketogenic/fatty acid substrate phenotype with concomitant decline in mitochondrial function and exacerbation of bioenergetic deficits in the 3xTgAD brain.

General significance

These findings provide a plausible mechanism for increased life-time risk of AD in postmenopausal women and suggest an optimal window of opportunity to prevent or delay decline in bioenergetics during reproductive senescence.     

Meta-analysis on association between the ATP-binding cassette transporter A1 gene (ABCA1) and Alzheimer's disease

Purpose

In the past decade, a number of case–control studies have been carried out to investigate the relationship between ABCA1 polymorphisms and Alzheimer's disease (AD). However, these studies have yielded contradictory results. To investigate this inconsistency, a meta-analysis was performed.

Methods

Databases including PubMed, Web of Science, EMBASE and CNKI were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association.

Results

A total of 13 case–control studies, involving 6214 patients and 6034 controls for ABCA1 polymorphisms were included. In a combined analysis, the summary per-allele odds ratio for AD of the 219 K was 1.03 (95% CI: 0.93–1.14, p = 0.56). A meta-analysis of studies on the 883 M and 1587 K variant showed no significant overall association with AD, yielding a per-allele odds ratio of 1.10 (95% CI: 0.96–1.26, p = 0.16), and 1.09 (95% CI: 0.97–1.24, p = 0.16) respectively. Similar results were also found for heterozygous and homozygous. In the subgroup analysis by ethnicity, sample size, APOE status and onset type, no significant associations were found in almost all genetic models.

Conclusions

In summary, there was no significant association detected between ABCA1 R219K, I883M and R1587K polymorphisms and risk for AD.     

Quercetin glucosides promote ischemia-induced angiogenesis,but do not promote tumor growth

Aims

Dietary flavonoid intake shows a significant inverse association with mortality from coronary heart disease, incidence of myocardial infarction and stroke. Quercetin is one of the most common flavonoids in our diet and has several favorable biological activities. Quercetin glucosides, which are enzymatically trans-glycosylated isoquercitrin, have high water-solubility and bioavailability compared with quercetin. Here, we investigated the effects of quercetin glucosides on collateral development in a murine hindlimb ischemia model.

Main methods

We induced hindlimb ischemia in 24- to 32-week-old male C3H/HeJ mice by resecting the right femoral artery. Then, 0.5% carboxymethyl cellulose (control) or quercetin glucosides (100 mg/kg/day) were administered daily by gavage. Blood flow was monitored weekly by laser Doppler imaging.

Key findings

Recovery of blood flow to the ischemic leg was significantly enhanced by quercetin glucosides (blood flow ratio at 4 weeks: control, 0.57 ± 0.11; quercetin glucosides, 0.95 ± 0.10, p < 0.05). Furthermore, anti-CD31 immunostaining revealed that quercetin glucosides increased capillary density in the ischemic muscle (control, 200 ± 24/mm²; quercetin glucosides, 364 ± 41/mm², p < 0.01). Quercetin glucosides did not promote tumor growth. The beneficial effect of quercetin glucosides was abrogated in eNOS-deficient mice.

Significance

These results suggest that quercetin glucosides may have therapeutic potential to promote angiogenesis in ischemic tissue.     

Impaired cardiac mitochondrial function and contractile reserve following an acute exposure to environmental particulate matter

Background

It has been suggested that mitochondrial function plays a central role in cardiovascular diseases associated with particulate matter inhalation. The aim of this study was to evaluate this hypothesis, with focus on cardiac O₂ and energetic metabolism, and its impact over cardiac contractility.

Methods

Swiss mice were intranasally instilled with either residual oil fly ash (ROFA) (1.0 mg/kg body weight) or saline solution. After 1, 3 or 5 h of exposure, O₂ consumption was evaluated in heart tissue samples. Mitochondrial respiration, respiratory chain complexes activity, membrane potential and ATP content and production rate were assessed in isolated mitochondria. Cardiac contractile reserve was evaluated according to the Langendorff technique.

Results

Three hours after ROFA exposure, tissue O₂ consumption was significantly decreased by 35% (from 1180 ± 70 to 760 ± 60 ng-at O/min g tissue), as well as mitochondrial rest (state 4) and active (state 3) respiration, by 30 and 24%, respectively (control state 4: 88 ± 5 ng-at O/min mg protein; state 3: 240 ± 20 ng-at O/min mg protein). These findings were associated with decreased complex II activity, mitochondrial depolarization and deficient ATP production. Even though basal contractility was not modified (control: 75 ± 5 mm Hg), isolated perfused hearts failed to properly respond to isoproterenol in ROFA-exposed mice. Tissue O₂ consumption rates positively correlated with cardiac contractile state in controls (r² = 0.8271), but not in treated mice (r² = 0.1396).

General Significance

The present results show an impaired mitochondrial function associated with deficient cardiac contractility, which could represent an early cardiovascular alteration after the exposure to environmental particulate matter.     

Características antropométricas,funcionales y de fuerza explosiva de mujeres mayores de 50 años físicamente activas de la ciudad de Bogotá, Colombia

Objective

To analyze the relationship between different test measuring explosive strength and functionality of active women participating in a leisure sport program in order to describe the caracteristics of health status and look for tools for diagnosing and monitoring degenerative process.

Methods

This study was conducted on 102 women physically active and without risk factors. Anthropometric, functional independence and explosive strength tests were applied.

Results

Mean age 60.08±5.35 years; body mass index: 26.81±3.91; percentage of fat: 52.45±4.75; percentage of muscle mass: 37.24±6.77; tests of functional independence: maximum speed (30 meters): 9.39±1.92 s; speed-agility (30 meters): 12.93±1.59 s, and dynamic balance (6 meters): 21.9±8.01 s. Explosive Strength (Bosco test): Squat Jump: 12.23±3.05 cm, Countermovement Jump: 13.18±3.04 cm and Countermovement Jump Arm swing: 14.80±4.01 cm.

Conclusion

The statistical relationships found between body composition, explosive strength and functionality tests, are important tools for diagnosing and monitoring, and could improve the intervention models on the elderly.     

Leptin-mediated inflammatory signaling crucially links visceral fat inflammation to obesity-associated β-cell dysfunction

Aim

This study aimed to examine the causal relationship between adipokines released from visceral fat and pancreatic β-cell dysfunction in the state of obesity inflammation.

Main methods

Adipose tissue and adipocyte conditioned medium were obtained from epididymal fat of B6 mice on regular or high fat diet for 16 weeks. The latter were classified into two groups: overweight (OW, 40 ± 2 g) and obese (OB, 50 ± 2 g). Isolated mouse islets and NIT-1 cells were used to evaluate β-cell function.

Key findings

Fasting glucose, leptin, and interleukin-6 levels were increased in OW mice and were further elevated in OB mice. Adipocyte size and number of adipose macrophage infiltrations showed a similar trend. The augmentation of homeostasis model assessment of insulin resistance, islet hyperplasia and macrophage infiltration was noted only in OB mice_. The stimulation index was lower, but reactive oxygen species production was higher in islets isolated from OB mice than from controls. In epididymal fat conditioned medium, the increases in leptin, IL-6 and TNF-α production in OW mice were further elevated in OB mice except TNF-α. Adipose tissue conditioned medium suppressed the stimulation index of islets isolated from B6 mice but not from db/db mice. The suppressive effect was also reversed by co-treatment with N-acetylcysteine or NS-398 (a selective cyclooxygenase-2 inhibitor).

Significance

A markedly elevated leptin production from inflamed visceral fat could deteriorate β-cell function via leptin receptor-mediated oxidative stress and cyclooxygenase-2 activation in the development of obesity.     

IDH1 mutations is prognostic marker for primary glioblastoma multiforme but MGMT hypermethylation is not prognostic for primary glioblastoma multiforme

Purpose

To establish the frequency of IDH1 mutations and MGMT methylation in primary glioblastomas.

Experimental design

We screened primary glioblastoma multiforme (GBM) in a population-based study for IDH1 mutations and MGMT methylation and correlated them with clinical data.

Results

IDH1 mutations were detected in 5 of 40 primary glioblastomas (12,5%). Primary GBM patients carrying IDH1 mutations were significantly younger, mean age of 41 ± 5.06 years, than patients with wild-type IDH1, mean age of 57 ± 2,29 years, p = 0.011. The mean survival time of all GBM patients with and without IDH1 mutations was 19 months (5 cases) and 16 months (35 cases), respectively (p > 0,05). MGMT methylation was detected in 13 of the 40 patients (32,5%). MGMT-promoter methylation did not correlate with overall survival (OS; p > 0,05).

Conclusion

In summary, our study is the first study to investigate the IDH1 mutation status and MGMT methylation in primary GBMs in Turkish population and confirmed IDH1 mutation as a genetic marker for also primary GBMs. Our data are still insufficient for definite ascertainment; and our preliminary results suggest: IDH1 status shows an association with younger age and there is a lack of association between IDH1 mutation and survival time. Furthermore MGMT promoter methylation had no prognostic value and lower frequency in primary glioblastomas.     

Efecto de un programa de ejercicios fisioterapéuticos sobre el desempeño físico en adultos mayores institucionalizados

Objective

To evaluate changes in physical performance in institutionalized older adults through a program of physiotherapy exercises.

Materials and methods

A quasi-experimental study was conducted on adults over 60 years-old, institutionalized in Lima, Peru. The exercise program was implemented in 45 minutes sessions included warming-up, muscle strengthening exercises, balance, gait training and cooling phase, three times a week for 12 weeks. Physical performance was measured with the Short Physical Performance Battery (SPPB) one week before and after the intervention. It included 45 participants, of whom 16 did not attend any of the sessions and was used as a control group.

Results

The mean age was 77.6 ± 7.1 years, and 62.2% were women. The mean baseline SPPB was 7.0 ± 1.6 in the intervention group, and 6.9 ± 1.9 in the control group (P=.90). A change of 2.6 ± 1.8 was observed in the SPPB of the intervention group versus -1.4 ± 2.0 in the control group (P<.001).

Conclusions

The development of a physiotherapy exercise program for institutionalized elderly increases physical performance, which could be implemented in care centers for elderly.     

Apport de deux techniques d’analyse automatisées des examens [F] FDG TEP dans la discrimination des patients déments frontotemporaux et malades d’Alzheimer

Introduction

In younger patients, the in vivo clinical diagnosis of Alzheimer's disease (AD) and of the frontotemporal type (FTD) may be cumbersome. The gold standard diagnostic proof is currently still based upon pathology examination. It is crucial to find reliable techniques to make an accurate in vivo diagnosis and to differentiate the etiology of the dementia.

Patients and method

Twenty-four patients bearing clinically diagnosed AD (n = 16) and FTD (n = 8) underwent [¹⁸F] FDG-PET/CT brain scan. Four nuclear medicine physicians with varying expertise in neuroimaging read each scan according to: visual analysis; automated analysis computed by BRASS^® Hermes^® software; automated analysis computed by Cortex ID^® General Electric^® software. Interpretation aimed at assessing the global scan aspect, the cerebral metabolism per hemisphere (in five relevant regions) and the diagnostic degree of confidence. Diagnostic interpretations derived from visual and automated analyses were compared to clinical diagnosis. Inter-observer agreement and Kappa scores were calculated.

Results

Kappa analyses showed a gain in diagnostic accuracy for a nonexpert physician, a gain in diagnostic confidence with Cortex ID^® and a gain in interobserver diagnostic agreement with BRASS^®.

Conclusion

Using automated software such as Cortex ID^® or BRASS^® helps standardizing the interpretation of [¹⁸F] FDG distribution pattern in AD or FTD.     

Combinatorial anticancer effects of curcumin and 5-fluorouracil loaded thiolated chitosan nanoparticles towards colon cancer treatment

Background

Evaluation of the combinatorial anticancer effects of curcumin/5-fluorouracil loaded thiolated chitosan nanoparticles (CRC-TCS-NPs/5-FU-TCS-NPs) on colon cancer cells and the analysis of pharmacokinetics and biodistribution of CRC-TCS-NPs/5-FU-TCS-NPs in a mouse model.

Methods

CRC-TCS-NPs/5-FU-TCS-NPs were developed by ionic cross-linking. The in vitro combinatorial anticancer effect of the nanomedicine was proven by different assays. Further the pharmacokinetics and biodistribution analyses were performed in Swiss Albino mouse using HPLC.

Results

The 5-FU-TCS-NPs (size: 150 ± 40 nm, zeta potential: + 48.2 ± 5 mV) and CRC-TCS-NPs (size: 150 ± 20 nm, zeta potential: + 35.7 ± 3 mV) were proven to be compatible with blood. The in vitro drug release studies at pH 4.5 and 7.4 showed a sustained release profile over a period of 4 days, where both the systems exhibited a higher release in acidic pH. The in vitro combinatorial anticancer effects in colon cancer (HT29) cells using MTT, live/dead, mitochondrial membrane potential and cell cycle analysis measurements confirmed the enhanced anticancer effects (2.5 to 3 fold). The pharmacokinetic studies confirmed the improved plasma concentrations of 5-FU and CRC up to 72 h, unlike bare CRC and 5-FU.

Conclusions

To conclude, the combination of 5-FU-TCS-NPs and CRC-TCS-NPs showed enhanced anticancer effects on colon cancer cells in vitro and improved the bioavailability of the drugs in vivo.

General significance

The enhanced anticancer effects of combinatorial nanomedicine are advantageous in terms of reduction in the dosage of 5-FU, thereby improving the chemotherapeutic efficacy and patient compliance of colorectal cancer cases.     

Apolipoprotein M promotes mobilization of cellular cholesterol in vivo

Objective

The HDL associated apolipoprotein M (apoM) protects against experimental atherosclerosis but the mechanism is unknown. ApoM increases preβ-HDL formation. We explored whether plasma apoM affects mobilization of cholesterol from peripheral cells in mice.

Methods and results

ApoM-enriched HDL from apoM-transgenic mice increased the in vitro efflux of ³H-cholesterol from macrophages by 24 ± 3% (p < 0.05) as compared with HDL from wild type (WT) mice, thus confirming previous findings. However, apoM-free HDL was not poorer than that of WT HDL to mobilize ³H-cholesterol. ³H-cholesterol-labeled foam cells were implanted in the peritoneal cavity of apoM^−/−, WT and apoM-transgenic mice to assess the mobilization of cholesterol from foam cells in vivo and subsequent excretion into feces. The results showed a statistically non-significant trend towards increased mobilization of cellular cholesterol to plasma with increasing plasma apoM. However, the apoM-genotype did not affect the excretion of ³H-cholesterol in feces. Nevertheless, when apoM^−/−, apoM-transgenic and WT mice received a constant intravenous infusion of ¹³C₂-cholesterol/intralipid for 5 h, the rate of enrichment of blood free cholesterol with free ¹³C₂-cholesterol was significantly lower (consistent with an increase in flux of unlabeled free cholesterol into the plasma) in the apoM-transgenic (3.0 ± 0.9‰/h) as compared to WT (5.7 ± 0.9‰/h, p < 0.05) and apoM^−/− (6.5 ± 0.6‰/h, p < 0.01) mice.

Conclusion

The present data indicate that the plasma apoM levels modulate the ability of plasma to mobilize cellular cholesterol, whereas apoM has no major effect on the excretion of cholesterol into feces.     

Remodeling of white adipose tissue metabolism by physical training prevents insulin resistance

Aim

This study sought to determine the role of white adipose tissue (WAT) metabolism in the prevention of insulin resistance (IR) by physical training (PT).

Main methods

Male C57BL/6 J mice were assigned into groups CHOW-SED (chow diet, sedentary; n = 15), CHOW-TR (chow diet, trained; n = 18), CAF-SED (cafeteria diet, sedentary; n = 15) and CAF-TR (cafeteria diet, trained; n = 18). PT consisted of running sessions of 60 min at 60% of maximal speed conducted five days per week for eight weeks.

Key findings

PT prevented body weight and fat mass accretion in trained groups and prevented hyperglycemia, hyperinsulinemia, glucose intolerance and IR in the CAF-TR. The CAF-SED group presented higher leptin and free fatty acid and lower adiponectin serum levels compared with other groups. Lipolytic activity (in mmol/10⁶ adipose cells) stimulated by isoproterenol increased in CHOW-TR (16347 ± 3005), CAF-SED (18110 ± 3788) and CAF-TR (15837 ± 2845) compared with CHOW-SED (8377 ± 2284). The CAF-SED group reduced FAS activity compared with CHOW-SED and CHOW-TR, reduced citrate synthase activity and increased DGAT2 content compared with other groups. Both trained groups reduced G6PDH activity and increased the expression of p-AMPK (Thr172) compared with sedentary groups. CAF-SED group had lower levels of AMPK, p-AMPK (Thr172), ACC and p-ACC (Ser79) compared with other groups.

Significance

The prevention of IR by PT is mediated by adaptations in WAT metabolism by improving lipolysis, preventing an increase in enzymes responsible for fatty acid esterification and by activating enzymes that improve fat oxidation instead of fat storage.     

Unphosphorylated calponin enhances the binding force of unphosphorylated myosin to actin

Background

Smooth muscle has the distinctive ability to maintain force for long periods of time and at low energy costs. While it is generally agreed that this property, called the latch-state, is due to the dephosphorylation of myosin while attached to actin, dephosphorylated-detached myosin can also attach to actin and may contribute to force maintenance. Thus, we investigated the role of calponin in regulating and enhancing the binding force of unphosphorylated tonic muscle myosin to actin.

Methods

To measure the effect of calponin on the binding of unphosphorylated myosin to actin, we used the laser trap assay to quantify the average force of unbinding (F_unb) in the absence and presence of calponin or phosphorylated calponin.

Results

F_unb from F-actin alone (0.12 ± 0.01 pN; mean ± SE) was significantly increased in the presence of calponin (0.20 ± 0.02 pN). This enhancement was lost when calponin was phosphorylated (0.12 ± 0.01 pN). To further verify that this enhancement of F_unb was due to the cross-linking of actin to myosin by calponin, we repeated the measurements at high ionic strength. Indeed, the F_unb obtained at a [KCl] of 25 mM (0.21 ± 0.02 pN; mean ± SE) was significantly decreased at a [KCl] of 150 mM, (0.13 ± 0.01 pN).

Conclusions

This study provides direct molecular level-evidence that calponin enhances the binding force of unphosphorylated myosin to actin by cross-linking them and that this is reversed upon calponin phosphorylation. Thus, calponin might play an important role in the latch-state.

General significance

This study suggests a new mechanism that likely contributes to the latch-state, a fundamental and important property of smooth muscle that remains unresolved.     

Increased renal semicarbazide-sensitive amine oxidase activity and methylglyoxal levels in aristolochic acid-induced nephrotoxicity

Aims

Aristolochic acid (AA) nephrotoxicity is related to accumulation of methylglyoxal (MGO) and N^ε-(carboxymethyl)lysine (CML) in the mouse kidney. We studied the activity of renal semicarbazide-sensitive amine oxidase (SSAO), a key enzyme involved in MGO generation, in AA-treated mice, and investigated nephroprotective effects produced by metformin, a MGO scavenger.

Methods

Mice were orally administered water or metformin for 15 days (12 or 24 mg kg^− 1 day^− 1), and injected AA (5 mg kg^− 1 day^− 1) intraperitoneally for 8 days starting on day 8. Renal function was studied, and histopathological examination, determination of renal SSAO activity, and measurement of MGO levels were performed.

Key findings

Compared to control mice, AA-injected mice showed significant renal damage and approximately 2.7-fold greater renal SSAO activity (p < 0.05). Further, compared to control treatment, administration of 12 mg/kg metformin inhibited formation of renal lesions, and significantly decreased renal MGO levels (37.33 ± 9.78 vs. 5.89 ± 2.64 μg/mg of protein, respectively, p < 0.01). In the AA-treated mice, metformin also inhibited the accumulation of CML in renal tubules, but did not affect SSAO activity.

Significance

This study is the first to show elevated renal SSAO activity in AA-treated mice, which could be involved in MGO accumulation. Moreover, MGO scavenging by metformin reduces AA nephrotoxicity. These findings suggest that reducing MGO accumulation produces nephroprotection, revealing new therapeutic strategies for the management. SSAO is a key enzyme involved in MGO generation, and consequently, inhibition of renal SSAO activity is worth investigating in AA nephrotoxicity and other renal pathologies further.     

Clinical value of plasma pentraxin 3 levels for predicting cardiac troponin elevation after percutaneous coronary intervention

Aims

Post-procedural myocardial necrosis manifested by elevated cardiac troponin T (cTnT) often complicates percutaneous coronary intervention (PCI). Plasma pentraxin 3 (PTX3) levels are increased in patients with arterial inflammation and especially unstable angina pectoris (UAP). This study tested whether plasma PTX3 levels can predict post-PCI cTnT elevation.

Main methods

We evaluated 94 consecutive patients with AP and normal pre-PCI cTnT levels who underwent PCI. Pre-PCI virtual histology-intravascular ultrasound was performed to assess culprit plaque composition. Plasma PTX3 and serum hs-CRP levels were measured pre-PCI. Patients were divided into 2 groups according to presence (Group I, n = 34) or absence (Group II, n = 60) of post-PCI cTnT elevation > 3 × the upper limit of normal at 24 h after PCI.

Key findings

Plasma PTX3 (4.06 ± 2.05 ng/ml vs 2.17 ± 1.02 ng/ml, p < 0.001), serum hs-CRP levels (0.25 ± 0.03 vs 0.16 ± 0.03 mg/dl, p = 0.048), plaque burden (80.9 ± 5.3 vs 75.4 ± 10.6%, p = 0.047), presence of positive remodeling (59 vs 25%, p = 0.034), and percent necrotic core area (19.0 ± 7.4 vs 14.0 ± 5.9%, p = 0.046) were significantly higher in Group I than in Group II. Receiver-operating characteristic curve analysis showed that with a best cut-off value of 2.83 ng/ml, plasma PTX3 level (AUC 0.823) predicted post-PCI cardiac TnT elevation better than did serum hs-CRP level (AUC 0.618). Multiple logistic regression analysis showed that plasma PTX3 level was the most independent predictor of post-PCI cardiac cTnT elevation (OR: 2.65; 95% CI: 1.56–10.1; p = 0.003).

Significance

Plasma PTX3 level may be a useful marker for predicting post-PCI cardiac cTnT elevation, which is associated with inflammatory status of culprit lesions.     

The role of caldesmon and its phosphorylation by ERK on the binding force of unphosphorylated myosin to actin

Background

Studies conducted at the whole muscle level have shown that smooth muscle can maintain tension with low Adenosine triphosphate (ATP) consumption. Whereas it is generally accepted that this property (latch-state) is a consequence of the dephosphorylation of myosin during its attachment to actin, free dephosphorylated myosin can also bind to actin and contribute to force maintenance. We investigated the role of caldesmon (CaD) in regulating the binding force of unphosphorylated tonic smooth muscle myosin to actin.

Methods

To measure the effect of CaD on the binding of unphosphorylated myosin to actin (in the presence of ATP), we used a single beam laser trap assay to quantify the average unbinding force (F_unb) in the absence or presence of caldesmon, extracellular signal-regulated kinase (ERK)-phosphorylated CaD, or CaD plus tropomyosin.

Results

F_unb from unregulated actin (0.10 ± 0.01 pN) was significantly increased in the presence of CaD (0.17 ± 0.02 pN), tropomyosin (0.17 ± 0.02 pN) or both regulatory proteins (0.18 ± 0.02 pN). ERK phosphorylation of CaD significantly reduced the F_unb (0.06 ± 0.01 pN). Inspection of the traces of the F_unb as a function of time suggests that ERK phosphorylation of CaD decreases the binding force of myosin to actin or accelerates its detachment.

Conclusions

CaD enhances the binding force of unphosphorylated myosin to actin potentially contributing to the latch-state. ERK phosphorylation of CaD decreases this binding force to very low levels.

General significance

This study suggests a mechanism that likely contributes to the latch-state and that explains the muscle relaxation from the latch-state.     

Myocardial interstitial serotonin and its major metabolite, 5-hydroxyindole acetic acid levels determined by microdialysis technique in rat heart

Aims

The aim of this study was to elucidate myocardial interstitial serotonin (5-HT) kinetics in the heart, including 5-HT reuptake and enzymatic degradation to 5-hydroxyindole acetic acid (5-HIAA) via monoamine oxidase (MAO).

Main methods

Using microdialysis technique in anesthetized rats, we simultaneously monitored myocardial interstitial levels of 5-HT and its major metabolite, 5-HIAA, in the left ventricle and examined the effects of local administration of a MAO inhibitor, pargyline, or a 5-HT uptake inhibitor, fluoxetine.

Key findings

Pargyline increased dialysate 5-HT concentration from 1.8 ± 0.3 at baseline to 3.9 ± 0.5 nM but decreased dialysate 5-HIAA concentration from 20.7 ± 1.0 at baseline to 15.8 ± 1.4 nM at 60–80 min of administration. Fluoxetine increased dialysate 5-HT concentration from 1.9 ± 0.4 at baseline to 6.5 ± 0.9 nM at 60–80 min of administration, but did not change dialysate 5-HIAA concentration. Local administration of ADP (100 mM) increased dialysate 5-HT and 5-HIAA concentrations. Pargyline did not affect ADP-induced increase in dialysate 5-HT concentration but suppressed ADP-induced increase in dialysate 5-HIAA concentration during 60 min of ADP administration. Fluoxetine increased dialysate 5-HT concentration at 40–60 min of ADP administration, but did not affect ADP-induced increase in dialysate 5-HIAA concentration.

Significance

Simultaneous monitoring of myocardial interstitial 5-HT and 5-HIAA levels provides valuable information on 5-HT kinetics including reuptake and enzymatic degradation by MAO, which play a role in the regulation of myocardial interstitial 5-HT levels at baseline and when 5-HT levels are elevated.     

Is there any association of apolipoprotein E gene polymorphism with obesity status and lipid profiles? Tehran Lipid and Glucose Study (TLGS)

Aims

Considering the key role played by the apolipoprotein E (Apo E) gene in the regulation of lipid metabolism and obesity, the current study has evaluate the association between abdominal obesity and Apo E gene polymorphism in a population of Tehran.

Materials and methods

A cross-sectional study was performed on 345 men and 498 women, aged 19–86 years, selected from among participants of the Tehran Lipid and Glucose Study. The RFLP-PCR technique was employed to investigate polymorphism in the gene fragments. Based on the national survey of risk factors for non-communicable diseases of Iran, waist circumference (WC) cut off was set at 89 cm for men and 91 cm for women. The risk effect of obesity related variables and lipid profiles in two groups of WC were examined by logistic regression. For body mass index (BMI), waist to hip ratio (WHR), high-density lipoprotein-cholesterol (HDL-C), triglyceride (TG), fasting blood sugar (FBS), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and blood pressure (BP), the standard risk cut-offs were applied.

Results

Frequencies of E2, E3, and E4 alleles were 9.7, 73, and 14.6%, respectively. The presence of the E3 allele was significantly associated with higher TG level in subjects with high WC, while, the presence of E4 allele decreased the plasma HDL-C (E2:52.1 ± 13.1 vs., E3:48.9 ± 11.2 vs., E4:44.6 ± 10.6 mg/dl, p < 0.05), HDL-C2 (E2:20.4 ± 9.2 vs., E3:19.1 ± 8.8 vs., E4:16.3 ± 7.9 mg/dl, p < 0.05), and HDL-C3 (E2:32.1 ± 7.4 vs., E3:30.3 ± 6.2 vs., E4:28.3 ± 6.1 mg/dl, p < 0.05) in normal WC subjects. The presence of the E3 carrier increased the risk of having higher plasma TG, compared with the E2 carrier (95% CI OR = 1.91, 1.02–3.57; p = 0.04).

Conclusion

According to the results of this study, the E3 carrier, caused an approximately 90% increase in the levels of TG in the group with abdominal obesity.     

The AMPK-SIRT signaling network regulates glucose tolerance under calorie restriction conditions

Aims

SIRT1 and AMP-activated protein kinase (AMPK) share common activators, actions and target molecules. Previous studies have suggested that a putative SIRT1-AMPK regulatory network could act as the prime initial sensor for calorie restriction-induced adaptations in skeletal muscle—the major site of insulin-stimulated glucose disposal. Our study aimed to investigate whether a feedback loop exists between AMPK and SIRT1 in skeletal muscle and how this may be involved glucose tolerance.

Main methods

To investigate this, we used skeletal muscle-specific AMPKα1/2 knockout mice (AMPKα1/2^−/−) fed ad libitum (AL) or a 30% calorie restricted (CR) diet and L6 rat myoblasts incubated with SIRT1 inhibitor (EX527).

Key findings

CR-AMPKα1/2^−/− displayed impaired glucose tolerance (*p < 0.05), in association with down-regulated SIRT1 and PGC-1α expression (< 300% vs. CR-WT, ^±±p < 0.01). Moreover, AMPK activity was decreased following SIRT1 inhibition in L6 cells (~ 0.5-fold vs. control, *p < 0.05).

Significance

This study demonstrates that skeletal muscle-specific AMPK deficiency impairs the beneficial effects of CR on glucose tolerance and that these effects may be dependent on reduced SIRT1 levels.