A Cycle of Inflammatory Adipocyte Death and Regeneration in Murine Adipose Tissue

Adipose tissue (AT) expands by a combination of two fundamental cellular mechanisms: hypertrophic growth of existing adipocytes or through generation of new adipocytes, also known as hyperplastic growth. Multiple lines of evidence suggest a limited capacity for hyperplastic growth of AT in adulthood and that adipocyte number is relatively stable, even with fluctuations in AT mass. If the adipocyte number is stable in adulthood, despite well-documented birth and death of adipocytes, then this would suggest that birth may be coupled to death in a regenerative cycle. To test this hypothesis, we examined the dynamics of birth of new fat cells in relationship to adipocyte death by using high-fidelity stable isotope tracer methods in C57Bl6 mice. We discovered birth of new adipocytes at higher frequency in histological proximity to dead adipocytes. In diet-induced obesity, adipogenesis surged after an adipocyte death peak beyond 8 weeks of high-fat feeding. Through transcriptional analyses of AT and fractionated adipocytes, we found that the dominant cell death signals were inflammasome related. Proinflammatory signals were particularly evident in hypertrophied adipocytes or with deletion of a constitutive oxygen sensor and inhibitor of hypoxia-inducible factor, Egln1. We leveraged the potential role for the inflammasome in adipocyte death to test the adipocyte death-birth hypothesis, finding that caspase 1 loss of function attenuated adipocyte death and birth in murine visceral AT. These data collectively point to a regenerative cycle of adipocyte death and birth as a driver of adipogenesis in adult murine AT.

Abstract 313: Nonionic Acid is a Target Metabolite of Diabetic Microvasculopathy

Aim: The purpose of this study is to screen the target metabolites of diabetic microangiopathy in heart by use of whole heart metabolome analysis.

Methods: Diet-induced type 2 diabetic mouse were divided into two groups; control and those treated with diabetic remedy GLP-1 receptor agonist Ex-4 for 5 weeks. Mice were euthanized and analyzed at the age of 16 week-old.

Results: The capillary density of the T2DM was reduced as compared to those non-diabetic counterparts, which was restored by Ex4 treatment. Changes in angiogenic signals detected by immunoblotting analysis revealed that the phosphorylation levels of eNOS and AMPK were elevated by Ex-4, but those Akt remained unchanged. Tube formation assay revealed that Ex-4 increased tube length and branch points in HUVECs. Consistently with the trend that was observed in vivo experiment, AMPK and eNOS phosphorylation levels were enhanced by Ex4 without affecting Akt phosphorylation. To screen the candidate metabolites that is responsible for the diabetic microvasculopathy in GLP-1-dependent fashion, we performed metabolome analysis by using the whole heart of each mouse. The hierarchical cluster analysis revealed that nonanoic acid (NNA) was the only metabolite that increased in type 2 diabetic mice with concomitant decline by Ex-4 treatment. We next examined the impact of nonanoic acid on in vitro angiogenesis and found that NNA suppressed tube length and branch points in HUVECs in a dose-dependent fashion. Interestingly, NNA canceled eNOS and AMPK phosphorylation that was enhanced by Ex4.

Conclusion: GLP-1 ameliorated diabetic microvasculopathy via the AMPK and eNOS axis. NNA is presumably one of the novel anti-angiogenic metabolites that causes diabetic microangiopathy.

Dipeptidyl Peptidase 4 Inhibition Alleviates Shortage of Circulating Glucagon-Like Peptide-1 in Heart Failure and Mitigates Myocardial Remodeling and Apoptosis via the Exchange Protein Directly Activated by Cyclic AMP 1/Ras-Related Protein 1 Axis

BACKGROUND

Ample evidence demonstrates cardiovascular protection by incretin-based therapy using dipeptidyl peptidase 4 inhibitor (DPP4i) and glucagon-like peptide-1 (GLP-1) under either diabetic or nondiabetic condition. Their action on myocardium is mediated by the cyclic AMP (cAMP) signal; however, the pathway remains uncertain. This study was conducted to address the effect of DPP4i/GLP-1/cAMP axis on cardiac dysfunction and remodeling induced by pressure overload (thoracic aortic constriction [TAC]) independently of diabetes mellitus.

METHODS AND RESULTS

DPP4i (alogliptin, 10 mg/kg per day for 4 weeks) prevented TAC-induced contractile dysfunction, remodeling, and apoptosis of myocardium in a GLP-1 receptor antagonist (exendin [9-39])-sensitive fashion. In TAC, circulating level of GLP-1 (in pmol/L; 0.86 ± 0.10 for TAC versus 2.13 ± 0.54 for sham control) unexpectedly declined and so did the myocardial cAMP concentration (in pmol/mg protein; 33.0 ± 1.4 for TAC versus 42.2 ± 1.5 for sham). Alogliptin restored the decline in the GLP-1/cAMP levels observed in TAC, thereby augmented cAMP signaling effectors (protein kinase A [PKA] and exchange protein directly activated by cAMP 1 [EPAC1]). In vitro assay revealed distinct roles of PKA and EPAC1 in cardiac apoptosis. EPAC1 promoted cardiomyocyte survival via concomitant increase in B cell lymphoma-2 (Bcl-2) expression and activation of small G protein Ras-related protein 1 (Rap1) in a cAMP dose-dependent and PKA-independent fashion.

CONCLUSIONS

DPP4i restores cardiac remodeling and apoptosis caused by the pathological decline in circulating GLP-1 in response to pressure overload. EPAC1 is essential for cardiomyocyte survival via the cAMP/Rap1 activation independently of PKA.

Mania occurring during systemic lupus erythematosus relapse and its amelioration on clinical and neuroimaging follow-up

Psychiatric manifestations of systemic lupus erythematosus (SLE) that are commonly preceded by organic syndromes include confusional states, anxiety disorder, cognitive dysfunction, mood disorder and psychosis. A 35-year-old woman was admitted to hospital with a relapse of SLE. Laboratory data were exacerbated, with some physical symptoms, and her primary psychiatric symptom was mania. The symptoms were reduced by treatment with prednisolone, methylprednisolone and aripiprazole. Magnetic resonance imaging and single-photon emission computed tomography (SPECT) using 123I-IMP was then performed and analyzed with three-dimensional stereotactic surface projection. This case emphasizes that SLE can commence with organic syndromes and relapse with predominantly psychiatric symptoms, and that the treatment efficacy may be confirmed using a follow-up of SPECT.

Abstract 178: Exercise Augments Cardiac Akt Activity And Reverses Aging-related Systolic Dysfunction

Purpose: Aging is one of the primary factors causing left-ventricular (LV) remodeling and susceptibility to heart failure (HF). Clinical evidences demonstrate a sustained exercise (EX) ameliorates HF; however, the molecular mechanism underlying the aging-related LV remodeling remains uncertain and few data have demonstrated whether EX may be beneficial for the aging-related LV remodeling and contractility. Because preclinical studies indicate the pivotal role of protein kinase Akt in aging, we thus hypothesized whether EX may exert benefits on HF induced by aging in which Akt may play an essential role.

Methods: Male aged (40 w/o) and young (14 w/o) C57BL6 mice were subjected to the EX (45-min running (10~20m/s, 5-degree) on treadmill every second day for 15 weeks; agedC57EX and agedC57CON). To elucidate the role of Akt in aging heart, age- and gender-matched Akt knockout mice were also enrolled.

Results: Aging impairs both systolic and diastolic function without any changes in cardiac geometry. The systolic dysfunction of agedC57 reversed by EX with concomitant Akt activation; however, its diastolic dysfunction remained unaffected. EX enhanced cardiac Akt activity independently of aging. Aged AktKO exhibited systolic dysfunction to the more severe extent, which was reversed by EX.

Conclusions: Our study demonstrates that #1 Akt is essential for adaptive cardiac contractility both to EX and aging. #2 Aging promotes diastolic dysfunction independently of Akt axis.

Abstract 146: Biphasic Effect Of Cyclic Amp Axis On Cardiomyocyte Survival

Background: Persistent cardiac hypertrophy in response to pathological stimuli is results in maladaptive myocardial remodeling and cell death. Clinical evidence revealed that one of the most significantly beneficial medications for targeting heart failure with pathologic myocardial hypertrophy is beta1-adrenergic receptor (β1R) blockers. The molecular pathway of β1R is mediated by the second messenger cyclic AMP (cAMP). However, there are some debate regarding the role of cAMP in myocardial survival. We hypothesized whether there may be threshold concentration of cAMP in cell susceptibility to cardiomyocyte cell death.

Methods: Male 14-week-old C57BL6 mice were subjected to the surgery of thoracic aortic constriction (TAC) to induce pressure overload. Changes in apoptosis were evaluated in each heart section and in vitro culture of neonatal cardiomyocytes using TUNEL. To elucidate the concentration-dependent distinct effect of cAMP on myocardial cell death, we tested the different concentration of cell-permeable cAMP (8-br-cAMP) at low (60 μM) and high concentration (6 mM), and receptor-mediated cAMP-stimulators (Ex4; exendin-4, ISO; isoproterenol).

Results: In vitro analysis revealed that the high-cAMP and ISO exhibited marked increase in TUNEL-positivity (15.46%±3.09% for high-cAMP versus 6.71%±0.33% for ISO), which was reversed by Rp-cAMP (1.80%±0.17% and 2.05%±0.25%, respectively). Unexpectedly, the 8-p-Methoxyphenylthon-2-O-methyl-cAMP (pMe-cAMP, 50 μM), the specific activator of another cAMP-sensitive target Epac, reversed the high-cAMP-induced cell death even at a less extent compared to that observed by PKA-inhibitor Rp-cAMP (3.73%±0.70%). Serum depletion induced 3.22±0.24% of TUNEL-positive cell count of NRVM, which was reversed by pMe-cAMP, (50 μM) and Ex4 (1.74±0.18%, n=6, P<0.01), which was insensitive to PKA inhibition by Rp-cAMP (100 μM).

TAC increased myocardial apoptosis. TAC-CON heart exhibited 1.66-fold decrease in cardiac cAMP concentration compared to sham-CON. Ex4 ameliorated the TAC-induced cardiac dysfunction and apoptosis by increase in cAMP.

Conclusions: The cAMP-related cell death was mediated by PKA activation, which were reversed by Epac activation.

Abstract 205: Mitochondrial Sirt3 Is Upregulated By Glucagon-like Peptide-1 Receptor Activation And Contributes To Reversal Of Cardiac Mitochondrial Remodeling Induced By Type 2 Diabetes

RATIONALE: Sirtuin 3 (SIRT3) is a mitochondrial protein deacetylase that maintains basal ATP yield and its expression level is increased by fasting, exercise, and some NAD+ intermediates. We recently reported that the glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 (Ex-4) ameliorated cardiac mitochondrial remodeling in diabetic cardiomyopathy via increase in cardiac cyclic AMP (AJP2013). Because changes in cyclic AMP level is regulated by adenylyl cyclase which is one of the downstream target of Ex-4, we hypothesized that SIRT3 may involve in the Ex-4-mediated myocardial reverse remodeling of mitochondria in diabetic mice.

METHODS: Type 2 diabetic Mice (16-week old male) were allocated into experimental groups as follows: Ex-4 (24 nmole/kg/day, subcutaneously administrated by osmotic pump for 40 days, DIO/Ex-4) and vehicle control (DIO/CON). Heart samples and cultured rat neonatal cardiomyocytes were subjected to mitochondrial fractionation using density gradient.

RESULTS: Cardiac cyclic AMP concentration and phosphorylation of CREB were elevated in DIO-ex4, suggesting successful administration of Ex-4. Electron microscopic analysis revealed that Ex-4 reversed destroyed cristae structure and defragmented mitochondria of DIO/CON heart. The ratio of expression levels of Mitofusin-1 (Mfn1) and mitofusin-2 (Mfn2) was consistently suppressed by Ex-4 treatment, suggesting normalization of mitochondrial morphology. Of note, DIO-CON exhibited marked decrease in cardiac SIRT3 level compared to lean/nondiabetic counterpart, which was reversed by exendin-4 treatment. Pharmacological production of intracellular cAMP levels (Isoprotelenol (10 microM) and 8-bromo-cyclic AMP (1 mM)) increased SIRT3 mRNA in cultured primary cardiomyocytes. The AMP-activated protein kinase (AMPK) inhibitition blocked the increase in SIRT3 mRNA, indicating that the SIRT3 expression was regulated by AMPK-dependent manner.

CONCLUSIONS: Our results indicate that Ex-4 reversed abnormal suppression of SIRT3 in mitochondria via activating the PKA/AMPK-dependent pathway.

Neurotransmitters, psychotropic drugs and microglia: clinical implications for psychiatry

Psychiatric disorders have long and dominantly been regarded to be induced by disturbances of neuronal networks including synapses and neurotransmitters. Thus, the effects of psychotropic drugs such as antipsychotics and antidepressants have been understood to modulate synaptic regulation via receptors and transporters of neurotransmitters such as dopamine and serotonin. Recently, microglia, immunological/inflammatory cells in the brain, have been indicated to have positive links to psychiatric disorders. Positron emission tomography (PET) imaging and postmortem studies have revealed microglial activation in the brain of neuropsychiatric disorders such as schizophrenia, depression and autism. Animal models of neuropsychiatric disorders have revealed the underlying microglial pathologies. In addition, various psychotropic drugs have been suggested to have direct effects on microglia. Until now, the relationship between microglia, neurotransmitters and psychiatric disorders has not been well understood. Therefore, in this review, at first, we summarize recent findings of interaction between microglia and neurotransmitters such as dopamine, serotonin, norepinephrine, acetylcholine and glutamate. Next, we introduce up-to-date knowledge of the effects of psychotropic drugs such as antipsychotics, antidepressants and antiepileptics on microglial modulation. Finally, we propose the possibility that modulating microglia may be a key target in the treatment of various psychiatric disorders. Further investigations and clinical trials should be conducted to clarify this perspective, using animal in vivo studies and imaging studies with human subjects.

Abstract 204: Loss Of Akt Caused Aging-induced Cardiac Systolic Dysfunction But Is Independent From Comorbid Diastolic Dysfunction In Aging

PURPOSE: Aging is one of the primary factors causing cardiac dysfunction. Diastolic dysfunction (DD) is primary characteristics for aging-induced heart failure. Clinical evidences demonstrate a sustained exercise (EX) ameliorates DD; however, it remains unclear whether EX may ameliorate the aging-related DD and the underlying molecular mechanism. We thus evaluated whether EX may ameliorate cardiac dysfunction in aging and the role of Akt in the EX-induced effects on aging heart.

Methods: Male senescence-accelerated (SAM) mice (P10) and its aging-resistant control (R1) were allocated to exercise [EX; 60-min running on treadmill every single day for 6 months (P10-EX and R1-EX)] and exercise-free control groups (P10-ctl and R1-ctl). Age-matched C57BL6 mice were subjected to the same EX protocol (C57-EX and C57-ctl) to compare any influence of genetic background. To elucidate the role of Akt in aging-induced changes in heart, analysis of aged Akt knockout mice (AktKO) were conducted.

Results: At baseline, cardiac geometry of R1 strain revealed normal, whereas P10 strain exhibited reduced LV wall thickness and DD. The s-LVF of both strains was preserved. After EX, the body and heart weight of R1 mice were increased (BW; +6.7% and HW; +3.5% versus R1-ctl); however, EX had no influence on BW and HW of P10. EX promoted LV hypertrophy in R1, which was absent in P10-EX. The d-LVF of R1-EX was impaired but their s-LVF was unchanged. In contrast, s-LVF of P10-EX turned impaired [EF(%) 68.9±1.5 vs 74.3±1.2 for P10-ctl], whereas the underlying DD of P10 was unaffected by EX. In C57-EX, cardiac function exhibited the similar trends observed in R1-EX. Cardiac Akt activity of R1-EX and C57-EX were enhanced compared to controls, which was diminished in P10-EX. Aged AktKO exhibited impaired s-LVF [EF(%)61.3±1.0], nonetheless their DD remained unchanged [E/A=2.5±0.3, Dct (msec)= 35.0±2.4].

Conclusions: Our study demonstrates that #1 Akt is essential for adaptive response of LV hypertrophy to EX, #2 aging impairs Akt signaling in heart, leading to systolic dysfunction, and #3 Akt is independent from modulation of cardiac DD induced by aging. Clinical implications are drawn that the benefit of EX on DD may be irrelevant to the aged population.

Abstract 146: Glucagon-like Peptide-1 Receptor Activation Promotes Dual Benefits For Reversing Microvasculopathy And Mitochondrial Damage In Diabetic Heart

PURPOSE: Glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (Ex4) is a remedy for type 2 diabetes mellitus (T2DM). Ex4 ameliorates cardiac dysfunction in preclinical and clinical settings. However, it remains unclear whether the impact of Ex4 on cardiac remodeling in diabetic cardiomyopathy (DMC), of which primary characteristics are microvasculopathy and mitochondrial damage.

Methods and Results: Diet-induced T2DM (DIO) mice and age- and gender-matched lean control mice were allocated into EX4 (24 nmole/kg/day for 40 days; DIO-Ex4 and LEAN-Ex4) and vehicle groups (DIO-veh and LEAN-veh). We first confirmed the GLP-1R expression in every single chamber of mouse heart by immunoblotting and PCR. Ex4 treatment ameliorated both systemic and cardiac insulin resistance without affecting body weight in DIO. Cardiac capillary density of DIO-veh was reduced compared to those LEAN-veh, which were reversed by Ex4 treatment. Tube formation assay and immunoblot analysis using culture endothelial cells revealed that Ex4 directly enhanced in vitro angiogenesis in a PKA/eNOS-dependent fashion. Systolic and diastolic left-ventricular (LV) dysfunctions observed in DIO-veh were restored by Ex4 with decline in LV wall thickening. Myocardial fibrosis detected using sirius-red staining and tissue oxidative stress detected by a fluorescence indicator DHE were attenuated in DIO-Ex4. Of note, analyses using transmission electron microscopy and a fluorescence indicator for damaged mitochondria (mitotracker red) revealed that Ex4 treatment reversed cardiac mitochondrial remodeling and increased healthy mitochondria. Ex4 treatment modulated cardiac oxidative stress balance by upregulating antioxidative molecules (SOD, thioredoxin, glutathione peroxidase) and reduction of NOX4 level; whereas it had no influence on NOX2 level.

Conclusions: Ex4 enhances cardiac angiogenesis via GLP-1R-mediated activation of PKA/eNOS axis and accelerates reverses remodeling of myocardial mitochondria, at least in part, via its facilitating effects on antioxidative defense.

Abstract 147: Glucagon-like Peptide-1 Receptor Activation Reverses Cardiac Mitochondrial Remodeling In Advanced Type 2 Diabetes Via Suppression Of Nox4

PURPOSE: Damaged cardiac mitochondria are one of the critical features of diabetic cardiomyopathy. We indeed demonstrated that diet-induced type 2 diabetes mellitus (T2DM) exhibited cardiac mitochondria remodeling, which were reversed by glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (Ex4) (submitted as another abstract to BCVS 2013); however, it remains unclear whether the mitochondrial remodeling induced by diabetes may be reversible even at an advanced disease stage and Ex4 may be strong enough to exhibit the cardioprotective effects on such a progressive T2DM.

Methods and Results: Genetic T2DM model (KKAy mice of which casual blood glucose levels is more than 30 mmol/L) were allocated into exendin-4 (Ex4, 24 nmole/kg/day for 40 days; KK-Ex4) and vehicle groups (KK-v). In KK-v, their systolic left-ventricular (LV) function was normal range, whereas they exhibited diastolic LV dysfunction and myocardial hypertrophy, which were ameliorated by Ex4. Myocardial fibrosis and cardiac steatosis (detected by Oil-red-O-staining and anti-ceramide antibody) were reduced in KK-ex4. Transmission electron microscopy revealed that Ex-4 normalized cardiac mitochondrial remodeling in terms of morphology, size, and number observed in KK-v. Ex4 attenuated mitochondrial damage which was detected by its specific dye mitotracker-red and alternatively monitored by mitofusin (Mfn)1/Mfn2 ratio. DHE staining revealed that Ex-4 reduced cardiac oxidative stress observed in KK-v. Ex4 modulated cardiac oxidative stress balance by reduction of NOX4 level; whereas it had no influence on NOX2 level and antioxidative molecules (SOD, thioredoxin, glutathione peroxidase), contrarily to those cases observed in diet-induced T2DM heart.

Conclusions: Mitochondrial remodeling induced by T2DM was found to be reversible even at an advanced disease stage and Ex4 was strong enough to exhibit the cardioprotective effects on such a progressive T2DM by attenuating cardiac oxidative stress, at least in part, by suppression of NOX4.

Glucagon-like peptide-1 receptor activation reverses cardiac remodeling via normalizing cardiac steatosis and oxidative stress in type 2 diabetes

Glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (Ex-4) is a remedy for type 2 diabetes mellitus (T2DM). Ex-4 ameliorates cardiac dysfunction induced by myocardial infarction in preclinical and clinical settings. However, it remains unclear whether Ex-4 may modulate diabetic cardiomyopathy. We tested the impact of Ex-4 on two types of diabetic cardiomyopathy models, genetic (KK) and acquired T2DM induced by high-fat diet [diet-induced obesity (DIO)], to clarify whether Ex-4 may combat independently of etiology. Each type of mice was divided into Ex-4 (24 nmol·kg(-1)·day(-1) for 40 days; KK-ex4 and DIO-ex4) and vehicle (KK-v and DIO-v) groups. Ex-4 ameliorated systemic and cardiac insulin resistance and dyslipidemia in both T2DM models. T2DM mice exhibited systolic (DIO-v) and diastolic (DIO-v and KK-v) left ventricular dysfunctions, which were restored by Ex-4 with reduction in left ventricular hypertrophy. DIO-v and KK-v exhibited increased myocardial fibrosis and steatosis (lipid accumulation), in which were observed cardiac mitochondrial remodeling and enhanced mitochondrial oxidative damage. Ex-4 treatment reversed these cardiac remodeling and oxidative stress. Cytokine array revealed that Ex-4-sensitive inflammatory cytokines were ICAM-1 and macrophage colony-stimulating factor. Ex-4 ameliorated myocardial oxidative stress via suppression of NADPH oxidase 4 with concomitant elevation of antioxidants (SOD-1 and glutathione peroxidase). In conclusion, GLP-1R agonism reverses cardiac remodeling and dysfunction observed in T2DM via normalizing imbalance of lipid metabolism and related inflammation/oxidative stress.

Anti-Inflammatory properties of antipsychotics via microglia modulations: are antipsychotics a 'fire extinguisher' in the brain of schizophrenia?

Schizophrenia is one of the most severe psychiatric diseases noted for its chronic and often debilitating processes; affecting approximately 1% of the world's population, while its etiology and therapeutic strategies still remain elusive. In the 1950s, the discovery of antipsychotic effects of haloperidol and chlorpromazine shifted the paradigm of schizophrenia. These drugs proved to be antagonists of dopamine D2 receptor (D2R), thus dopamine system dysfunction came to be hypothesized in the pathophysiology of schizophrenia, and D2R antagonism against dopamine neurons has been considered as the primary therapeutic target for schizophrenia. In addition, abnormalities of glutamatergic neurons have been indicated in the pathophysiology of schizophrenia. On the other hand, recent neuroimaging studies have shown that not only dementia but also schizophrenic patients have a significant volume reduction of some specific regions in the brain, which indicates that schizophrenia may involve some neurodegenerative process. Microglia, major sources of various inflammatory cytokines and free radicals such as superoxide and nitric oxide (NO) in the CNS, play a crucial role in a variety of neurodegenerative diseases such as dementia. Recent postmortem and positron emission computed tomography (PET) studies have indicated that activated microglia may be present in schizophrenic patients. Recent in vitro studies have suggested the anti-inflammatory effects of antipsychotics on microglial activation. In this article, we review the anti-inflammatory effects of antipsychotics on microglia, and propose a novel therapeutic hypothesis of schizophrenia from the perspective of microglial modulation.

Atorvastatin prevents ischemic limb loss in type 2 diabetes: role of p53

AIM

Diabetic peripheral artery disease (PAD) is prone to be aggressive and recent reports have demonstrated that p53 accumulation may be responsible for impaired wound healing in diabetes. Statins has been demonstrated to facilitate p53 degradation by activating its specific ubiquitin ligase, MDM2. The aim of this study was to determine whether atorvastatin (ATR) improves the outcome of diabetic PAD through MDM2-mediated reduction of p53.

METHODS

Male KK/Ay mice (9 weeks old) were treated with ATR (2 mg/kg/day p.o.) or vehicle for 2 weeks and subjected to ischemic hindlimb operation to generate a diabetic PAD model. Incidences of amputation and changes of p53/MDM2 signaling in each ischemic limb were assessed 2 weeks after the operation (at 13 weeks of age). Effects of ATR on the insulin resistance of age-matched (13-week-old) and unoperated KK/Ay mice were assessed by the glucose tolerance test, circulating adiponectin concentration, and changes in insulin signaling (IRS-1/Akt phosphorylation).

RESULTS

In intact KK/Ay, ATR treatment mitigated insulin resistance without affecting cholesterol levels. All diabetic PAD models exhibited autoamputation (100%); however, ATR treatment partially restored the limb loss (41.7%). The p53 expression level in the ischemic limb of ATR-treated KK/Ay was significantly decreased and MDM2 phosphorylation level was markedly increased in tandem with the activation of Akt. Hypoxia mimetic iron chelator deferroxamine promoted p53 accumulation in H9c2 myoblast cells by suppressing the Akt/MDM2 pathway, which was restored by ATR.

CONCLUSIONS

ATR was found to restore ischemic limb loss in diabetes by augmenting p53 degradation through direct activation of the Akt/MDM2 pathway in skeletal muscle.

Simultaneous measurement of arterial transit time, arterial blood volume, and cerebral blood flow using arterial spin-labeling in patients with Alzheimer disease

BACKGROUND AND PURPOSE

Cerebral hemodynamics abnormality in Alzheimer disease (AD) is not fully understood. Our aim was to determine whether regional hypoperfusion due to AD is associated with abnormalities in regional arterial blood volume (rABV) and regional arterial transit time (rATT) as measured by quantitative arterial spin-labeling (ASL) with multiple-delay time sampling.

MATERIALS AND METHODS

Nineteen patients with AD (9 men and 10 women; mean age, 74.5 +/- 8.6 years) and 22 cognitively healthy control subjects (11 men and 11 women; mean age, 72.8 +/- 6.8 years) were studied by using a quantitative ASL method with multiple-delay time sampling. From the ASL data, maps of regional cerebral blood flow (rCBF), rABV, and rATT were generated. A region of hypoperfusion due to AD was determined by statistical parametric mapping (SPM) analysis. Mean rCBF, rABV, and rATT values within the hypoperfused region were compared between the AD and control groups.

RESULTS

Despite the significantly lower rCBF (P = .0004) in patients with AD (27.8 +/- 7.1 mL/100 g/min) in comparison with control subjects (36.7 +/- 6.3 mL/100 g/min), no significant difference in rATT was observed between the control (0.48 +/- 0.09 seconds) and AD (0.47 +/- 0.10 seconds) groups. Mean rABV was lower in the AD group (0.22 +/- 0.10%) than in the control group (0.27 +/- 0.12%), though the difference did not reach the level of statistical significance.

CONCLUSIONS

Our results revealed that regional hypoperfusion in AD is not associated with rATT prolongation, suggesting that the mechanism of hypoperfusion is distinct from that in cerebrovascular diseases.

Use of a three-dimensional microarray system for detection of levofloxacin resistance and the mec A gene in Staphylococcus aureus

We evaluated a novel three-dimensional microarray (Pam Chip microarray) system to detect the presence of levofloxacin-related resistance mutations and the mec A gene. The results were compared to those obtained for 27 Staphylococcus aureus isolates by conventional DNA sequencing or PCR methods. Hybridization and fluorescence detection were performed using an FD 10 system designed for Pam Chip microarray under conditions optimized for each target/probe on the array. In dilution series analysis using multiplex PCR samples, the sensitivity of the microarray was about 10 times greater than that of conventional PCR methods. A high level of data reproducibility was also confirmed in those analyses. Various point mutations in quinolone resistance-determining regions detected by our system corresponded perfectly to the results obtained by conventional DNA sequencing. The results of the mec A gene detection using our system also corresponded to the PCR method; that is, signal/band was detected in all isolates of methicillin-resistant S. aureus, and no signal/band was detected in any isolate of methicillin-susceptible S. aureus. In conclusion, our novel three-dimensional microarray system provided rapid, specific, easy, and reproducible results for the simultaneous detection of levofloxacin resistance and the mec A gene in S. aureus.

Rapid detection of fluoroquinolone resistance by isothermal chimeric primer-initiated amplification of nucleic acids from clinical isolates of Neisseria gonorrhoeae

To ensure a complete response to fluoroquinolone therapy against Neisseria gonorrhoeae infections, rapid susceptibility determinations are required. We assessed a new approach, an isothermal chimeric primer-initiated amplification of nucleic acids (ICAN)/hybrid-chromatography method to detect rapidly fluoroquinolone resistance in N. gonorrhoeae. Comparison of the amplification results with fluoroquinolone minimum inhibitory concentrations (MICs), which were determined by an agar dilution method, showed that the new method accurately determined fluoroquinolone resistance in all ciprofloxacin- and/or gatifloxacin-resistant isolates, but agreed with results based on MICs in only 6 of 8 (75.0%) ciprofloxacin-susceptible and 7 of 12 (58.3%) gatifloxacin-susceptible isolates. Our results suggest that this method can rapidly and reliably detect point mutations in the gyrA gene as well as fluoroquinolone resistance in resistant isolates of N. gonorrhoeae.

Release of exotoxin A, peptidoglycan and endotoxin after exposure of clinical Pseudomonas aeruginosa isolates to carbapenems in vitro

BACKGROUND

Production of several cell-associated components and extracellular enzymes can play important roles in the pathogenesis of Pseudomonas aeruginosa infections.

METHODS

We characterized the time course of morphological changes, production of exotoxin A (ETA) and release of peptidoglycan (PG) and endotoxin (ET) in clinical P. aeruginosa isolates after exposure to carbapenems including imipenem, panipenem, meropenem and biapenem at 0.5, 2, 8 and 32 microg/ml.

RESULTS

The amount of ETA in the supernatant of bacterial cultures exposed to carbapenems correlated with the number of viable cells, independently of morphological changes. Formation of ovoid cells and rapid cell lysis induced by carbapenems above the minimal inhibitory concentrations (MICs) decreased ETA production and ET release, while filamentation and prolonged cell lysis increased ETA production and/or ET release. Neither the number of viable cells nor bacterial morphology was related to the amount of PG released throughout the 6-hour observation period.

CONCLUSION

Exposure to concentrations of carbapenems above the MIC resulted in rapid cell lysis of P. aeruginosa and decreased ETA levels and ET release, while filamentation and prolonged cell lysis induced by exposure to sub-MICs of carbapenems were associated with increased ETA production and/or greater ET release.

Tyrosinase induction and inactivation in normal cultured human melanocytes by endothelin-1

Since endothelin was found to be expressed in epithelial cells as well as in vascular endothelial cells, the functional regulation of melanocytes with endothelin has been actively investigated. In particular, it has been suggested that endothelin may influence pigmentation and depigmentation, which are mediated by melanocytes. In the present study, we investigated the regulation of melanocyte function and tyrosinase expression by endothelin from the point of view of tyrosinase protein expression and enzyme activity. The influence of endothelins on melanocyte function was assessed. Melanocytes showed a dose-dependent increase in cell proliferation with the addition of endothelin-1. When the confluence of melanocytes was cultured with endothelin-1 for 72 h, tyrosinase activity in melanocytes was significantly and dose-dependently decreased. In contrast, there was no significant change with endothelin-3. However, tyrosinase protein expression of melanocytes was significantly and dose-dependently increased by endothelin-1, but endothelin-3 had no effect. Both the suppression of enzyme activity and the enhanced protein expression were regulated by the ETA receptor antagonist, BQ123. In view of these observations, we conclude that endothelin-1-induced tyrosinase is mediated by ETA receptors. However, the reason for the decrease in the specific activity of tyrosinase remains unknown, and our results suggest that another mechanism underlying the activation of tyrosinase is present in addition to the inductive action of endothelin-1 on tyrosinase.

Detection of mutations in quinolone resistance-determining regions in levofloxacin- and methicillin-resistant Staphylococcus aureus: effects of the mutations on fluoroquinolone MICs

The minimum inhibitory concentrations (MICs) of 18 antibiotics were determined for 66 clinical isolates of staphylococci. Genotypes, mutations in the quinolone resistance-determining regions (QRDRs), and effect of efflux were determined in the 18 levofloxacin-resistant isolates, for which the MICs of levofloxacin were high (> or =8 microg/ml). The increased levofloxacin resistance mainly resulted from some combinations of mutations in the QRDRs, although NorA-mediated efflux may play a minor role in resistance. A combination of mutations in GrlA (Ser80Phe), GrlB (Pro451Ser), and GyrA (Ser84Leu) was found in 4 methicillin-resistant Staphylococcus aureus (MRSA) isolates that were unrelated genotypically. The mutations in grlA QRDR varied in the isolates classified as being in an identical pulsed-field gel electrophoresis (PFGE) group, although the grlB, gyrA, and gyrB QRDRs were the same. These results suggest that the patterns of amino acid mutations in the QRDRs can provide distinct epidemiologic information from PFGE genotypes in fluoroquinolone-resistant MRSA. A combination of at least three mutations in GrlA, GrlB, and/or GyrA is required to increase the MICs of fluoroquinolones, although all of the levofloxacin-resistant MRSA retained the MICs of sitafloxacin in the range of 1 to 2 microg/ml.

The relationship between the aggregational state of the amyloid-beta peptides and free radical generation by the peptides

In the present study, we investigated whether or not the amyloid-beta protein (Abeta) peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of Abeta and Abeta-induced cytotoxicity. The present results demonstrated a four-line spectrum in the presence of both Abeta40 and Abeta42 with Ntert-butyl-alpha-phenylnitrone (PBN), but not in the presence of PBN alone in phosphate-buffered saline (PBS). The fact that the four-line spectrum obtained for the Abeta/PBN in PBS was completely abolished in the presence of the iron-chelating agent Desferal demonstrated the observed four-line spectrum to be iron-dependent. The present study also revealed that either Abeta40 or Abeta42 with PBN in phosphate buffer (PB) did not produce any definite four-line spectrum. Both a thioflavine-T (Th-T) fluorometric assay and circular dichroism (CD) spectroscopy showed the amyloid fibril formation of Abeta in PBS to be much higher than that of Abeta in PB. Moreover, Abeta-induced cytotoxicity assays showed Abeta incubated in PBS to be more cytotoxic than that incubated in PB. These results thus suggest that Abeta-associated free radical generation is strongly influenced by the aggregational state of the peptides.

The relationship between Abeta-associated free radical generation and Abeta fibril formation revealed by negative stain electron microscopy and thioflavine-T fluorometric assay

In the present study, we investigated whether or not the Abeta peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also observing the Abeta fibril formation by negative stain electron microscopy. The present results demonstrated a four-line spectrum in the presence of Abeta(1-40) with N-tert-butyl-alpha-phenylnitrone (PBN) but not in the presence of PBN alone in phosphate-buffered saline. Negative stain electron microscopy has shown that Abeta peptides after 96 h of incubation showed more amyloid-like fibrils than those after 72 h of incubation while the four-line spectrum obtained by ESR spectroscopy attained a maximum intensity after 72 h of incubation and thereafter its intensity immediately decreased during the 4-day incubation period. These results were also supported by a thioflavine-T (Th-T) fluorometric assay. In conclusion, the present results suggest that Abeta-associated free radical generation is correlated with Abeta fibril formation while its generation is only observed transiently during the process of Abeta fibril formation.

Inhibition of A beta fibril formation and A beta-induced cytotoxicity by senile plaque-associated proteins

A beta neurotoxicity is generally believed to require A beta fibril formation. The prevention of A beta fibril formation thus seems to be a promising strategy for the treatment of AD. Recent studies have shown senile plaque-associated proteins such as laminin to have an inhibitory effect on both A beta40 and A beta42 fibril formation in vitro. In the present study, we thus investigated whether or not midkine (MK) and alpha2-macroglobulin (alpha2M), both of which are also senile plaque-associated proteins like laminin, affect A beta fibril formation and A beta-induced cytotoxicity. The present study demonstrated that both MK and alpha2M inhibit both A beta fibril formation and A beta-induced cytotoxicity in PC12 cells. The confirmation of the present results based on in vivo experiments is called for in future studies to clarify whether or not senile plaque-associated proteins such as MK and alpha2M can be a model for therapeutic agents in the treatment of AD.

An IKLLI-containing peptide derived from the laminin alpha1 chain mediating heparin-binding, cell adhesion, neurite outgrowth and proliferation, represents a binding site for integrin alpha3beta1 and heparan sulphate proteoglycan

We synthesized and characterized several peptides containing the IKLLI sequence in the alpha1 chain of laminin-1. The IKLLI-containing peptides, such as LA4 (CSRNLSEIKLLISRARK), LA5 (EIKLLIS) and LA5L (SEIKLLIS), were found to mediate heparin binding and cell adhesion, while also promoting neurite outgrowth in PC12 cells. Furthermore, peptides LA4 and LA5 also mediated proliferation. However, a scrambled peptide, LA5S (ILEKSLI), did not show any of these activities. Anti-LA4 antibodies inhibited laminin- and LA5-mediated cell adhesion and neurite outgrowth, and anti-(integrin alpha3) and anti-(integrin beta1) antibodies inhibited LA5-mediated cell adhesion and neurite outgrowth. Heparin and heparan sulphate inhibited LA5-mediated heparin binding and PC12 cell adhesion in a dose- dependent manner. The IC50 for inhibition of heparin binding and cell adhesion was observed with 9 microM and 8 microM heparin/heparan sulphate respectively. Furthermore, heparan sulphate proteoglycan also inhibited LA5-mediated PC12 cell adhesion with an IC50 of 100 micrograms/ml. However, chondroitin sulphate (dermatan sulphate) did not inhibit cell adhesion. These data suggest that an IKLLI-containing peptide derived from the laminin alpha1 chain may be an active site of laminin and that its cell adhesion may thus interact with both integrin alpha3beta1 and cell- surface heparan sulphate proteoglycan.

Laminin inhibits both Abeta40 and Abeta42 fibril formation but does not affect Abeta40 or Abeta42-induced cytotoxicity in PC12 cells

Laminin has recently been reported to inhibit both Abeta40 and Abeta42 fibril formation in vitro. Laminin was thus suggested to be an effective therapeutic agent for Alzheimer's disease. However, some recent reports have shown that Abeta fibril formation may not necessarily be linked to the development of Abeta neurotoxicity. In the present study, we thus investigated whether or not laminin affects Abeta40 and Abeta42-induced neurotoxicity. The findings of the present study by using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) dye reduction test showed laminin not to have an inhibitory effect on Abeta40 or Abeta42-induced cytotoxicity in PC12 cells while Abeta fibril formation was inhibited under the conditions used in the present study. The findings of the present study therefore do not support the hypothesis that Abeta fibril formation is absolutely required for the development of Abeta cytotoxicity.

Identification of a heparin binding site and the biological activities of the laminin alpha1 chain carboxy-terminal globular domain

The carboxy-terminal globular domain (G-domain) of the laminin alpha1 chain has been shown to promote heparin binding, cell adhesion, and neurite outgrowth. In this study, we defined the potential sequences originating from the G-domain of laminin alpha1 chain which possess these functional activities. A series of peptides were synthesized from the G-domain, termed LG peptides (LG-1 to LG-6) and were tested for their various biological activities. In the direct [3H] heparin binding assays, LG-6 (residues 2,335-2,348: KDFLSIELVRGRVK) mediated high levels of [3H]heparin binding, and this peptide also directly promoted cell adhesion and spreading, including B16F10, M2, HT1080, and PC12 cells. The peptide LG-6 also promoted the neurite outgrowth of PC12 cells, mouse granule cells, and chick telencephalic cells. An anti-peptide LG-6 antibody inhibited laminin-1 and peptide LG-6-mediated cell adhesion and neurite outgrowth. Furthermore, an anti-integrin alpha2 antibody also inhibited the cell adhesion activity. These results suggest that peptide LG-6 plays a functional role as a heparin binding site in the G-domain of the laminin alpha1 chain, and this sequence was thus concluded to play a crucial role in regulating cell adhesion and spreading and neurite out-growth which is related to integrin alpha2.

The inhibitory effect of laminin 1 and synthetic peptides deduced from the sequence in the laminin alpha1 chain on Abeta40 fibril formation in vitro

We investigated whether or not laminin 1 and the two different synthetic peptides deduced from the sequence in the laminin alphal chain, both of which mediate cell attachment and neurite outgrowth in PC12 cells, have an effect on Abeta40 fibril formation in vitro. A thioflavine-T fluorometric assay showed a synthetic peptide containing the YFQRYLI sequence from the laminin alpha1 chain to inhibit Abeta40 fibril formation while the inhibitory effect of this peptide was found to be somewhat less than that of intact laminin 1. These results were confirmed by electron microscopic observations using negative staining. The findings of the present study suggested that the synthetic peptide derived from the laminin alpha1 chain may thus be an effective therapeutic agent for either preventing or slowing down the progression of amyloidogenesis in Alzheimer's disease.

Laminin inhibits A beta 40 fibril formation promoted by apolipoprotein E4 in vitro

The aggregation of soluble A beta into insoluble amyloid fibrils is believed to be an important step in the pathogenesis of Alzheimer's disease (AD) and the prevention of this process therefore seems to be a promising strategy for the treatment of AD. Both apolipoprotein E(apoE) and laminin are known to play important roles in the regeneration of the central nervous system and both are known to accumulate in the senile plaques of the AD brains. In the present study, we therefore investigated whether or not laminin has any effect on A beta 40 fibril formation promoted by apoE4 in vitro. A thioflavine-T fluorometric assay and electron microscopic observations using negative staining together demonstrated that laminin inhibits A beta 40 fibril formation in vitro while it also inhibits A beta 40 fibril formation promoted by apoE4. These results suggested that either laminin or its derivatives may thus be effective as therapeutic agents for AD.

Laminin inhibits Abeta42 fibril formation in vitro

In the present study, we investigated whether or not laminin inhibits Abeta42 fibril formation in the same manner as Abeta40. Both a thioflavine-T fluorometric assay and electron microscopy by negative staining demonstrated laminin to have a concentration-dependent inhibitory effect on Abeta42 fibril formation. The amyloid fibril formation was inhibited approximately by 70% due to the presence of 1.0 mg/ml laminin co-incubated with 1. 0 mg/ml Abeta42 peptide (molar ratio; Abeta42 peptide:laminin=200:1). These results thus suggested that laminin or its derivatives may be effective as therapeutic agents to either prevent or slow down the progression of amyloidogenesis in Alzheimer's disease.

The number of noradrenergic and adrenergic neurons in the brain stem does not change with age in male Sprague-Dawley rats

We examined whether or not the number of noradrenergic and adrenergic neurons changes with age, using peroxidase antiperoxidase (PAP) immunohistochemistry with specific antisera against tyrosine hydroxylase (TH) and phenylethanolamine-N-methyltransferase (PNMT). TH- and PNMT-immunoreactive neurons were counted in every noradrenergic and adrenergic neuron group of young (3-month-old) and old (24-month-old) rats. The differences in the counted number of TH- and PNMT-immunoreactive neurons did not reach statistical significance between the young and old rats.

Effect of dietary vitamin E on lipofuscin accumulation with age in the rat brain

We investigated the effect of dietary vitamin E on lipofuscin accumulation with age in the hippocampus, the inferior olive and the cerebellum of young (3-5 months old) middle-aged (12-14 months old) and old (24-26 months old) male Sprague-Dawley rats. The rats were fed either a vitamin E-deficient diet, vitamin E-supplemented diet or a control diet after reaching four weeks old. We employed both quantitative light microscopy using semithin sections and qualitative fluorescence microscopy for the analysis of lipofuscin accumulation with age. The concentrations of alpha-tocopherol were measured simultaneously in both the plasma and the three brain regions investigated. The effect of vitamin E deficiency was statistically significant only in the inferior olive of young rats and in all the three brain regions of middle-aged rats. The effect of vitamin E supplementation was statistically significant in all three brain regions of middle-aged rats. There was no statistically significant effect of vitamin E deficiency or supplementation on lipofuscin accumulation with age as compared with the control rats in all three brain regions of old rats. It was thus revealed that dietary vitamin E clearly had a significant effect on lipofuscin accumulation with age in the rat brain up until middle age, and that the same effect became indistinct in the latter half of their life.