Effect of high ambient temperature on physiological responses during incremental exercise in Thoroughbred horses

Several reports have suggested that the risk of exertional heat illness (EHI) in Thoroughbred racehorses increases in high ambient temperatures. Heat dissipation in horses during exercise becomes less efficient when the body temperature and ambient temperature are close. Therefore, we hypothesised that exercise at 40 °C may increase body temperature, oxygen consumption, and cardiac output during incremental exercise tests compared to 20 and 30 °C. Six trained Thoroughbred horses were studied in a randomised, crossover design at three ambient temperatures with a 6-day washout period. Using a 3% inclined treadmill, horses performed incremental exercise tests at 1.7, 3.5, 6, 8, and 10 m/s for 90 s at ambient temperatures of 20, 30, and 40 °C. The effects of ambient temperature at 10 m/s on physiological variables were analysed using mixed models (P<0.05). Pulmonary arterial temperature and rectal temperature at 40 °C were higher than those at 20 °C (P<0.001) and 30 °C (P<0.001). Similarly, oxygen consumption (vs 20 °C, P=0.009; vs 30 °C, P=0.006) and cardiac output (vs 20 °C, P=0.001; vs 30 °C, P=0.001) at 40 °C were higher than those at 20 and 30 °C. Arterial O2 partial pressure, O2 saturation, and pH at 40 °C were lower than those at 20 and 30 °C. Arterial CO2 partial pressure at 40 °C was higher than that at 20 and 30 °C. No differences were observed in arterial-mixed venous O2 concentration difference (P=0.391) and plasma lactate concentration (P=0.134) at different ambient temperatures. These results indicate that exercise at 40 °C causes excessive high body temperature, decreased running economy, and increased cardiac output compared to exercise at 20 and 30 °C. We strongly suggest that trainers and veterinarians should anticipate the occurrence of increased thermal stresses when ambient temperature is extremely high even in dry conditions and prepare to mitigate the risk of EHI from the perspective of equine welfare.

Effect of post-exercise muscle cooling on PGC-1α and VEGF mRNA expression in Thoroughbreds

Besides preventing exertional heat illness, muscle cooling can be a potential strategy to enhance exercise-training induced adaptations. This study aimed to examine the effects of post-exercise cooling on the mRNA expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and vascular endothelial growth factor (VEGF) in Thoroughbred skeletal muscle. Five Thoroughbred horses performed treadmill running until their pulmonary artery temperature reached 42 °C, followed by walking on the treadmill with no additional cooling (CONT) or muscle cooling with a shower using the tap water (26 °C, 0.4 l/s; COOL), for 30 min. Muscle biopsies were obtained before (PRE) and 3 h after exercise (3 Hr-REC) from the gluteus medius muscle. PGC-1α mRNA expression was elevated 3 h after exercise in both the CONT (PRE vs 3 Hr-REC: 1.0±0.1 vs 5.0±0.8, P<0.01) and COOL (PRE vs 3 Hr-REC: 1.1±0.3 vs 6.6±0.9, P<0.01) conditions; however, there was no difference between the two conditions at 3 h after exercise (P=0.17). VEGF mRNA expression was elevated 3 h after exercise in COOL (PRE vs 3 Hr-REC: 1.0±0.2 vs 2.2±0.2, P<0.05) but not in CONT (PRE vs 3 Hr-REC: 1.0±0.1 vs 1.8±0.3, P=0.08). VEGF mRNA expression at 3 h after exercise was significantly negatively correlated with rectal temperature at the end of the 30-min cooling period (r = -0.65, P<0.05). Our results suggest that the decline in body temperature after exercise may lead to greater expression of the key angiogenic gene in Thoroughbred horses.

Comparison of the Japan Society of Clinical Chemistry reference method and CDC method for HDL and LDL cholesterol measurements using fresh sera

Objectives

In 2009, the Japan Society of Clinical Chemistry (JSCC) recommended a reference method for the measurement of serum high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels. This automated method uses cholesterol esterase-cholesterol dehydrogenase to measure cholesterol levels in fractions obtained after ultracentrifugation and dextran sulfate/magnesium chloride precipitation. In the present study, using fresh samples, we compared the LDL-C and HDL-C levels measured using this method with those measured using the traditional Centers for Disease Control and Prevention (CDC)-beta-quantification (BQ) method.

Design

and methods: Using both the JSCC and CDC-BQ methods, LDL-C/HDL-C levels were measured in 47 non-diseased and 126 diseased subjects, whose triglyceride levels were lower than 11.29 ​mmol/L (1000 ​mg/dL).

Results

For LDL-C, the equation of the line representing the correlation between the two methods was y ​= ​0.991x + 0.009 ​mmol/L; r ​= ​0.999; and Sy/x ​= ​0.025 ​mmol/L, where x is the mean LDL-C level measured using the CDC-BQ method. Similarly, for HDL-C, the equation of the line representing the correlation between the two methods was y ​= ​0.988x + 0.041 ​mmol/L, r ​= ​0.999, and Sy/x ​= ​0.019 ​mmol/L, where x is the mean HDL-C level measured using the CDC-BQ method.

Conclusions

The JSCC method agreed with the CDC-BQ method in cases of both non-diseased and diseased subjects, including those with dyslipidemia.

•

Using both the JSCC and BQ methods, LDL-C/HDL-C levels were measured.

•

The JSCC method agrees with the BQ method.

•

The JSCC reference method is an accurate, simple, and automatable method.

•

The JSCC method is suitable for quantitative analysis of LDL-C and HDL-C levels.

Changes in muscle activity with exercise-induced fatigue in Thoroughbred horses

Understanding the effects of fatigue can provide guidance for training regimens and injury prevention. We have previously reported that the integrated-electromyogram (iEMG) values of the M. gluteus medius and brachiocephalicus decreased with exercise-induced fatigue, whereas those of the M. longissimus dorsi and infraspinatus were not affected. We hypothesised that exercise-induced fatigue would decrease the activities of the muscles associated with propulsive force but not associated with joint stabilisation. Surface EMG recordings of the forelimb muscles (M. triceps brachii, common digital extensor, ulnaris lateralis), and hindlimb muscles (M. semitendinosus, extensor digitorum longus, extensor digitorum lateralis and flexor digitorum lateralis) were conducted on eight Thoroughbreds. Horses galloped on a treadmill (grade, 3%) at a constant speed (12.6-14.8 m/s) until they could not maintain their position with minimal human encouragement (~5 min). The stride frequency, iEMG for a stride and median frequency during muscle discharge were calculated every 30 s. These parameters were compared between the start and end of the test phase for the leading and trailing limbs. The stride frequency (P<0.01) and iEMG values of the M. semitendinosus in both the leading (P<0.01) and trailing limbs (P<0.05) and those of the M. extensor digitorum longus in the trailing limbs (P<0.05) significantly decreased at the end of the test. No median frequency changes were observed in the assessed muscles. Although muscular fatigue itself was not detected, observed fatigue caused by high-intensity exercise resulted in inability to maintain speed, which was associated with decreased iEMG values in the hip extensor muscles that generate propulsive force. In contrast, almost all muscles that stabilise joints were unaffected by fatigue. One exception was the decreased muscle activity observed in the M. extensor digitorum longus of the trailing limb, which may suggest unstable ground contact. Muscle activity changes with fatigue might be associated with muscle functions.

Effect of lactate administration on exercise-induced PGC-1α mRNA expression in Thoroughbreds

The aim of this study was to examine the effects of lactate administration on the mRNA response of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) to acute exercise in Thoroughbred skeletal muscle. Five Thoroughbred horses performed treadmill running at 90% of maximal oxygen consumption for 2 min on two separate occasions, either after the administration of two litres of a sodium lactate solution (LAC; 500 mmol/l sodium lactate in 0.9% NaCl) or a saline solution as a control (CON; 0.9% NaCl). Lactate administration significantly elevated the peak plasma lactate concentration during exercise (16.0±2.8 mmol/l in LAC vs 10.8±2.2 mmol/l in CON). The increase in PGC-1α mRNA expression after 4 h of recovery from exercise was similar between treatments. However, there was positive correlation between exercise-induced PGC-1α mRNA response at 4 h after exercise and peak plasma lactate concentration during exercise. These results suggest that the exercise intensity-dependent adaptation of PGC-1α may be attributed, at least in part, to an increased lactate concentration.

Impact of sitagliptin combination therapy and hypoglycemia in Japanese patients with type 2 diabetes: a multi-center retrospective observational cohort study

Background

Patients with diabetes are at higher risk of developing polypharmacy because of the high frequency of comorbidities. There have been several reports on the hypoglycemic risk of the combination of hypoglycemic agents and other medications. This study aimed to investigate the hypoglycemic risk of drug-drug interaction between sitagliptin and other oral hypoglycemic agents or antihypertensive agents in Japanese patients with type 2 diabetes.

Methods

From January 2010 to March 2012, a total of 3247 patients were recruited and evaluated at outpatient clinics at Juntendo University Hospital, other satellite hospitals, and private clinics. This study was a sub-analysis of the Sitagliptin Registration Type 2 Diabetes-Juntendo Collaborating Project. Participants were limited to those treated with oral hypoglycemic agents, excluding insulin users, to investigate the association of the first hypoglycemic events with oral hypoglycemic agents or other medications within 6 months after starting sitagliptin. The factors related to the first hypoglycemic event were analyzed using Cox regression analysis.

Results

In total, 2956 patients with a mean age of 65.1 ± 11.3 years were included. A total of 46 hypoglycemic events (1.6%) were observed. One patient had severe hypoglycemia followed by emergency transport to the hospital. Sitagliptin was not associated with hypoglycemia, but its combination with sulfonylurea (hazard ratio: 4.42, 95% confidential interval: 1.36–14.42) or β-blocker (hazard ratio, 3.50, 95% confidential interval: 1.54–7.96) was significantly associated with hypoglycemia.

Conclusions

The drug-drug interactions between sitagliptin and sulfonylurea or β-blocker likely increases the hypoglycemic risk in Japanese patients with type 2 diabetes. Pharmacists should consider potential adverse events from drug-drug interaction in type 2 diabetes with polypharmacy, particularly those who are managed by several doctors or clinics.

Real-World Data on the Incidence of Macrovascular Complications in Japanese Patients with Type 2 Diabetes: The Sitagliptin Registration Type 2 Diabetes-Juntendo Collaborating Project

INTRODUCTION

Type 2 diabetes is associated with vascular complications that deteriorate the quality of life and decrease the life expectancy of individuals. We previously reported the efficacy of sitagliptin for glucose control in patients with type 2 diabetes in the Sitagliptin Registration Type 2 Diabetes-Juntendo Collaborating Project (SPIRITS-J). Through the results of the SPIRITS-J study, we expected that optimal comprehensive management of type 2 diabetes according to current clinical practice guidelines in addition to achieving individualized glycemic goals would reduce macrovascular complications and all-cause mortality in Japan. The aim of this study was to evaluate this hypothesis.

METHODS

We investigated the clinical outcomes prospectively in the extended SPIRITS-J study and compared these to previous Japanese cohort studies in the era before widespread use of guidelines. The primary clinical outcome was a composite of myocardial infarction (MI), stroke, and all-cause mortality.

RESULTS

Mean duration of follow-up was 3.5 ± 1.3 years. The crude incidence of the primary outcome per 1000 person-years was 13.9 (non-fatal MI 1.44, non-fatal stroke 4.22, all-cause mortality 8.79 per 1000 person-years, respectively). It is noteworthy that the incidence of MI in the SPIRITS-J study was very much lower than that in a previous Japanese cohort study. In multivariate analysis, both the history of coronary artery disease and low-density lipoprotein cholesterol (LDL-C) were independently associated with incidence of primary clinical outcome.

CONCLUSION

The extended SPIRITS-J study demonstrated that optimal comprehensive management in patients with type 2 diabetes according to the recent practice guidelines has succeeded in preventing macrovascular complications in Japan. This study suggests that more intensive LDL-C-lowering therapy is important for further prevention of macrovascular complications even in Japanese patients with type 2 diabetes (UMIN 000004121).

The Goal of Achieving Atherosclerotic Plaque Regression with Lipid-Lowering Therapy: Insights from IVUS Trials

Enormous effort has been put into the prevention of atherosclerosis through risk modification, especially with lipid-lowering therapies. Regression, that is, the reversal of the atherosclerosis process, has long been a goal of atherosclerosis research among basic and clinical investigators. Intravascular ultrasound (IVUS) was developed in the 1990s as an intracoronary imaging technique to observe the details of the vessel walls and to measure the vessel lumen and plaque area with high reproducibility. Compared with the coronary angiogram, IVUS provides far more detailed information on the vessel wall. In this article, we review lipid-lowering trials that have used IVUS and discuss the current understanding of the effectiveness of aggressive lipid-lowering therapy, which inhibits atherosclerotic progression and induces regression and plaque stabilization.

Efficacy and safety of sitagliptin in Japanese patients with type 2 diabetes

BACKGROUND

The aim of this study was to investigate the clinical efficacy and safety of sitagliptin in Japanese patients with type 2 diabetes.

METHODS

A total of 3,247 subjects treated with sitagliptin were retrospectively recruited. Glucose parameters were collected at baseline, and 1, 3 and 6 months after initiation of sitagliptin. In addition, we explored factors that can be used to predict sitagliptin-induced reduction in HbA1c using linear mixed effect model. Factors associated with hypoglycemic events were examined by logistic analyses.

RESULTS

We analyzed the available data of 3,201 subjects (1,287 females). Treatment of sitagliptin significantly reduced HbA1c level from 7.44±1.20% at baseline to 6.73±0.99% at 6 months (P < 0.0001). Linear mixed effect model analyses demonstrated that reduction of HbA1c was associated with higher baseline HbA1c level, younger age, lower BMI and sitagliptin monotherapy. During this study, 82 cases of hypoglycemia were recorded. Logistic analyses indicated that hypoglycemic events were more frequent in female patients, and patients with low BMI, long history of type 2 diabetes, high HbA1c and on combination therapy experienced. Other adverse events were rare and mild.

CONCLUSIONS

Sitagliptin is effective for diabetic management and generally well tolerated in Japanese patients with type 2 diabetes. This trial was registered with UMIN (no. 000004121).

Albumin concentration determined by the modified bromocresol purple method is superior to that by the bromocresol green method for assessing nutritional status in malnourished patients with inflammation

BACKGROUND

The controlling nutritional status (CONUT) score (CS), a simple score for assessing nutritional status, is calculated using laboratory data, including serum albumin concentration. Although dye-binding assays such as the bromocresol green (BCG) and modified bromocresol purple (mBCP) methods are widely used for albumin measurement, acute-phase proteins interfere with the BCG method.

OBJECTIVE

We aimed to determine whether the choice of albumin assay affects assessment of nutritional status using CONUT scores (CSs).

DESIGN

We measured serum albumin concentrations by the BCG (ALBBCG) and mBCP (ALBmBCP) methods in 44 malnourished inpatients, 27 of whom underwent nutritional intervention, and compared them to 30 age-matched healthy volunteers. In treated patients, CSs were calculated by ALBBCG (CS-BCG) and ALBmBCP (CS-mBCP).

RESULTS

C-reactive protein (CRP) concentrations were positively correlated with the difference between ALBBCG and ALBmBCP in malnourished inpatients (r = 0.59, p < 0.001). CS-BCG was always lower than CS-mBCP (lower CS indicates superior nutritional status) in treated patients with persistently high CRP levels. However, in patients whose CRP decreased gradually, this difference diminished over the clinical course. CS-BCG and CS-mBCP were similar throughout their courses in patients with normal CRP concentrations. Adding haptoglobin to the human albumin solutions increased ALBBCG in a dose-dependent manner.

CONCLUSIONS

The choice of albumin assay affected the assessment of nutritional status using CSs in patients with inflammation. We recommend that the modified BCP assay be used to assess nutritional status, particularly in patients with inflammation.

Gossypol inhibits aromatase activity in cultured porcine granulosa cells

The present study investigated whether gossypol inhibited aromatase activity in cultured porcine granulosa cells. Aromatase activity was assayed by measuring (3)H-H(2)O released from [1beta-(3)H]-androstenedione. First, immature porcine granulosa cells were cultured with various doses of follicle stimulating hormone (FSH, 1 to 1000 ng/ml) for 1 to 5 d to determine optimal culture conditions for aromatase activity assay. Second, porcine granulosa cells were cultured with or without FSH in the presence or absence of gossypol. Gossypol, at 4 muM, significantly inhibited FSH-induced aromatase activity while showing no effect on basal aromatase activity. Gossypol did not inhibit cell proliferation during cell culture. These results suggest that gossypol inhibits aromatase activity by interfering with FSH induction of aromatase in cultured porcine granulosa cells.

Clinical significance of the measurements of urinary liver-type fatty acid binding protein levels in patients with acute coronary syndrome

BACKGROUND

Recently, much attention has been focused on cardio-renal interaction. Urinary liver-type fatty acid binding protein (U-L-FABP), which is produced in the proximal tubule by renal hypoxia and oxidative stress, has been identified as a useful marker for diagnosis of acute kidney disease and a predictor of future events in chronic kidney disease. However, the clinical significance of U-L-FABP measurements in patients with acute coronary syndrome (ACS) has not been completely evaluated.

METHODS AND RESULTS

This study included 50 consecutive patients with ACS [37 with acute myocardial infarction (AMI) and 13 with unstable angina pectoris (UAP)] and 47 subjects without coronary artery disease (control group). U-L-FABP levels, urinary albumin (U-Alb), and other serum parameters were measured at admission and at 24 h after percutaneous coronary intervention.

RESULTS

U-L-FABP levels in patients with AMI were significantly higher (p=0.0019), than in control subjects, while patients with UAP did not exhibit such an increase. U-L-FABP levels at admission were positively correlated with brain natriuretic protein levels (p=0.001) and duration of hospitalization (p=0.025). At follow-up angiography, patients with restenosis had significantly higher U-L-FABP (p=0.047) and U-Alb levels (p<0.0001) than those without restenosis. After a median follow-up of 42 months, U-L-FABP levels at second measurement in patients with major adverse cardiocerebrovascular events (MACCEs) were significantly higher than those in patients without MACCEs (p=0.028). After adjusting for confounding factors, high U-L-FABP levels at second measurement were found to be independent factors for MACCEs (p=0.019).

CONCLUSIONS

These data suggest that patients with ACS, especially those with AMI, have high U-L-FABP levels, and that U-L-FABP measurements may be useful in identifying high-risk patients for future cardiovascular events after ACS.

Non-high-density lipoprotein cholesterol is a practical predictor of long-term cardiac death after coronary artery bypass grafting

BACKGROUND

Recent studies have demonstrated that non-high-density lipoprotein cholesterol (non-HDL-C) can predict the risk of cardiovascular events among general population without coronary heart disease (CHD). However, few studies have investigated the predictive value of non-HDL-C for long-term prognosis in patients with CHD. The purpose of this study was to investigate whether non-HDL-C can predict long-term cardiovascular events in patients with CHD who underwent coronary artery bypass grafting (CABG).

METHODS

We enrolled 1074 consecutive patients who underwent CABG at Juntendo University Hospital between 1984 and 1994, and obtained mortality data through 2000. We divided the patients into 2 groups by the median non-HDL-C level at baseline (180 mg/dL) and used Kaplan-Meier method with log-rank test for survival analyses. Cox proportional-hazard regression model was used to calculate the relative risk (RR) of cardiac death.

RESULTS

The mean follow-up period was 10.6±3.5 years. The survival rate of cardiac death was significantly lower in the high non-HDL-C group than that in the low non-HDL-C group (log-rank test; p=0.006). Furthermore, in proportional regression analysis adjusted for conventional coronary risk factors, metabolic syndrome, statin treatment, and use of artery bypass graft, the increased levels of non-HDL-C were significant and independent predictor of cardiac death beyond other lipid parameters (RR1.22; by 10 mg/dL non-HDL-C increasing, 95% confidence interval 1.03-1.44; p<0.05).

CONCLUSIONS

The increased levels of non-HDL-C were significantly associated with an increased risk of cardiac death. Baseline non-HDL-C levels may be a practical predictor of long-term cardiac death in patients with CHD after CABG.

Comparison of net anaerobic energy utilisation estimated by plasma lactate accumulation rate and accumulated oxygen deficit in Thoroughbred horses

REASONS FOR PERFORMING STUDY

Accumulated O(2) deficit (AOD) and plasma lactate accumulation rate (PLAR) are alternative methods for estimating net anaerobic energy utilisation (NAEU) in exercising horses. How they compare or their accuracy is unknown.

OBJECTIVES

We hypothesised net anaerobic energy utilisation calculated by PLAR (NAUE(PLAR)) is equivalent to NAUE estimated by AOD (NAUE(AOD)).

METHODS

Six Thoroughbred horses ran at identical supramaximal speeds (118% aerobic capacity) until exhaustion for 2 runs while breathing normoxic (NO, 21% O(2)) or hyperoxic (HO, 26% O(2)) gas. Jugular blood was sampled at 15 s intervals to measure plasma lactate concentration. Horses also ran at incremental submaximal speeds from 1.7-11.0 m/s to determine the linear relationship between speed and O(2) consumption to estimate O(2) demand for AOD calculations.

RESULTS

Maximum O(2) consumption of horses increased 11.6 ± 2.3% in HO and NAEU(PLAR) and NAUE(AOD) decreased 38.5 ± 8.0% and 46.2 ± 17.7%, respectively. The NAEU(PLAR) in NO was 114.5 ± 27.4 mlO(2) (STPD) equivalent/kg bwt contributing 23.5 ± 3.7% to total energy turnover and in HO was 70.9 ± 19.8 mlO(2) (STPD) equivalent/kg bwt contributing 14.6 ± 3.8% to total energy turnover. The NAUE(AOD) in NO was 88.6 ± 24.3 mlO(2) (STPD) equivalent/kg bwt contributing 19.9 ± 2.1% to total energy turnover and in HO was 56.2 ± 19.1 mlO(2) (STPD) equivalent/kg bwt contributing 10.9 ± 4.3% to total energy turnover. Overall, NAEU(AOD) was systematically biased -23.5 ± 16.8 mlO(2) (STPD) equivalent/kg bwt below NAEU(PLAR). Total energy demand estimated by PLAR was 11.1 ± 5.4% greater than that estimated by AOD and was higher in every horse.

CONCLUSIONS

The NAUE(PLAR) estimates average 40.0 ± 29.6% higher than NAUE(AOD) and are highly correlated (r(2) = 0.734), indicating both indices are sensitive to similar changes in NAEU. Accuracy of the estimates remains to be determined. Multiple considerations suggest NAUE(AOD) may underestimate total energy cost during high-speed galloping, thus biasing low the AOD estimate of NAEU.

Effects of three warm-up regimens of equal distance on VO2 kinetics during supramaximal exercise in Thoroughbred horses

REASONS FOR PERFORMING STUDY

Several studies have indicated that even low-intensity warm-up increases O(2) transport kinetics and that high-intensity warm-up may not be needed in horses. However, conventional warm-up exercise for Thoroughbred races is more intense than those utilised in previous studies of equine warm-up responses.

OBJECTIVES

To test the hypothesis that warm-up exercise at different intensities alters the kinetics and total contribution of aerobic power to total metabolic power in subsequent supramaximal (sprint) exercise in Thoroughbred horses.

METHODS

Nine well-trained Thoroughbreds ran until fatigue at 115% of maximal oxygen consumption (VO2max) 10 min after warming-up under each of 3 protocols of equal running distance: 400 s at 30% VO2max (LoWU), 200 s at 60% VO2max (MoWU) and 120 s at 100% VO2max (HiWU). Variables measured during exercise were rates of O(2) and CO(2) consumption/production (VO2,VO2), respiratory exchange ratio (RER), heart rate, blood lactate concentration and accumulation rate and blood gas variables.

RESULTS

VO2 was significantly higher in HiWU than in LoWU at the onset of the sprint exercise and HR was significantly higher in HiWU than in LoWU throughout the sprint. Accumulation of blood lactate, RER, P(a)CO(2) and PvCO2 in the first 60 s were significantly lower in HiWU than in LoWU and MoWU. There were no significant differences in stroke volume, run time or arterial-mixed venous O(2) concentration.

CONCLUSIONS

These results suggest HiWU accelerates kinetics and reduces reliance on net anaerobic power compared with LoWU at the onset of the subsequent sprint.

Impact of diabetes on muscle mass, muscle strength, and exercise tolerance in patients after coronary artery bypass grafting

BACKGROUND

The impact of diabetes mellitus (DM) on muscle mass, muscle strength, and exercise tolerance in patients who had undergone coronary artery bypass grafting (CABG) has not been fully elucidated.

METHODS

We enrolled 329 consecutive patients who received cardiac rehabilitation (CR) after CABG (DM group, n=178; non-DM group, n=151) and measured lean body weight, mid-upper arm muscle area (MAMA), and handgrip power (HGP) at the beginning of CR. We also performed an isokinetic strength test of the knee extensor (Ext) and flexor (Flex) muscles and a cardiopulmonary exercise testing at the same time.

RESULTS

No significant differences in risk factors, including age, gender, number of diseased vessels, or ejection fraction were observed between the 2 groups. The levels of Ext muscle strength, peak oxygen uptake, and anaerobic threshold were significantly lower in the DM group than in the non-DM group (all p<0.05). Both peak oxygen uptake and MAMA correlated with Ext and Flex muscle strength as well as HGP (all p<0.005). The MAMA, HGP, and Ext muscle strength were lower in patients who received insulin therapy than in those who did not. Interestingly, fasting glucose levels significantly and negatively correlated with Ext muscle strength.

CONCLUSIONS

These data suggest that DM patients had a lower muscle strength and exercise tolerance than non-DM patients. Moreover, a high glucose level may affect these deteriorations in DM patients after CABG.

Small dense LDL cholesterol is a robust therapeutic marker of statin treatment in patients with acute coronary syndrome and metabolic syndrome

BACKGROUND

Small dense low-density lipoprotein (sd-LDL) is an atherogenic LDL subfraction and often increased in metabolic syndrome (MetS). This study aimed to determine whether sd-LDL cholesterol (sd-LDL-C) is a therapeutic marker of statin treatment in patients with acute coronary syndrome (ACS) and MetS.

METHODS

We examined 71 patients with ACS and 50 non-ACS subjects with normal coronary arteries (controls). The patients with ACS were treated with life-style modifications (n=36) or those plus 20mg atorvastatin daily (n=35) for 6 months. We measured sd-LDL-C by a novel detergent-based homogenous assay and calculated buoyant LDL-C (b-LDL-C).

RESULTS

The patients with ACS had higher sd-LDL-C than did the controls (30±14 vs. 22±8 mg/dl, p<0.001). Furthermore, sd-LDL-C was higher in the patients with ACS and MetS (n=31) than in those without MetS (n=40) (35±17 vs. 27±11 mg/dl, p<0.05). Atorvastatin reduced LDL-C and sd-LDL-C by 31% (102±23 to 70±28 mg/dl, p<0.0001) and 24% (29±15 to 22±13 mg/dl, p<0.01). The reduction in sd-LDL-C by atorvastatin was 5.5-fold greater in the patients with ACS and MetS than in those without MetS (p<0.001). Contrary, that in b-LDL-C was similar between the groups.

CONCLUSIONS

sd-LDL-C is a superior therapeutic marker of statin treatment in patients with ACS and MetS.

Profiles of inflammatory markers and lipoprotein subclasses in patients undergoing continuous ambulatory peritoneal dialysis

BACKGROUND

Patients undergoing continuous ambulatory peritoneal dialysis (CAPD) often have inflammation and dyslipidemia that accelerate to atherosclerosis. This study aimed to evaluate chronic inflammation and dyslipidemia in CAPD patients.

METHODS

We measured inflammatory markers and lipoprotein subclasses in 20 CAPD patients (12 men and 8 women, aged 59.5 ± 9.9 y) and 20 gender-matched controls. Lipoproteins were separated by high-performance liquid chromatography (HPLC) using an anion-exchange column.

RESULTS

High-sensitivity C-reactive protein and serum amyloid A protein (SAA) were higher among CAPD patients vs. controls (1.6 ± 2.2 vs. 0.8 ± 1.2 mg/l, p<0.05; 11.9 ± 12.8 vs. 4.5 ± 2.4 mg/l). HPLC analysis revealed that chylomicron, VLDL, and IDL cholesterol levels were higher among CAPD vs. controls. In contrast, HDL cholesterol was lower among CAPD patients vs. controls. In the subgroup analysis, SAA levels were significantly lower among patients receiving CAPD for >3 y than among controls. However, IDL cholesterol was consistently higher among CAPD patients vs. controls.

CONCLUSIONS

CAPD patients have chronic inflammation and dyslipidemia. IDL cholesterol is the only lipoprotein subclass that is consistently elevated regardless of CAPD duration. More attention should be paid to dyslipidemia in the management of the CAPD patients.

Utilisation of the time constant calculated from heart rate recovery after exercise for evaluation of autonomic activity in horses

REASONS FOR PERFORMING STUDY

Heart rate (HR) recovery immediately after exercise is controlled by autonomic functions and the time constant (T) calculated from HR recovery is thought to be an index of parasympathetic activity in man.

OBJECTIVES

To investigate whether it is possible to evaluate autonomic function using the time constant in horses.

METHODS

Five Thoroughbred horses were subjected to a standard exercise test. Following pre-medication with saline, atropine and/or propranolol, the horses ran for 2.5 min at a speed of 8 m/sec at a 10% incline and T was calculated from HR after the exercise. Secondly, 7 Thoroughbred horses were then trained for 11 weeks and T and maximal oxygen uptake (VO2max) measured at intervals of 1 or 2 weeks. In 6 horses, T with atropine pre-medication was also measured before and after the whole training period. Furthermore, the HR variability at rest was evaluated by power spectral analysis at intervals of 3 or 4 weeks.

RESULTS

Time constant was increased by atropine and/or propranolol pre-medication, decreased with the progress of training and inversely correlated with VO2max during training (r = 0.43, P<0.005). Parasympathetic blockade significantly decreased T only after and not before, the training; however, T was lower in post training than in pretraining, irrespective of parasympathetic blockade. On the other hand, parasympathetic activity at rest was attenuated and sympathetic activity became predominant following the training.

CONCLUSION

Heart rate recovery is affected by sympathetic withdrawal and parasympathetic reactivation in horses and suggests that physical training hastened HR recovery by improving the parasympathetic function after exercise with aerobic capacity. However, the effects of other factors need to be considered because the training effect appeared on T even under parasympathetic blockade. The parasympathetic activity at rest is in contrast to that after exercise, suggesting that T does not reflect parasympathetic activity at rest.

POTENTIAL RELEVANCE

If demonstrated how HR recovery is controlled after exercise, its analysis will be important in the evaluation of physical fitness in horses.

Effect of amino acid and glucose administration following exercise on the turnover of muscle protein in the hindlimb femoral region of Thoroughbreds

REASONS FOR PERFORMING STUDY

In man, muscle protein synthesis is accelerated by administering amino acids (AA) and glucose (Glu), because increased availability of amino acids and increased insulin secretion, is known to have a protein anabolic effect. However, in the horse, the effect on muscle hypertrophy of such nutrition management following exercise is unknown.

OBJECTIVES

To determine the effect of AA and Glu administration following exercise on muscle protein turnover in horses. We hypothesise that administration of AA and Glu after exercise effects muscle hypertrophy in horses, as already shown in man and other animals.

METHODS

Measurements of the rate of synthesis (Rs) and rate of degradation (Rd) of muscle protein in the hindlimb femoral region of thoroughbred horses were conducted using the isotope dilution method to assess the differences between the artery and iliac vein. Six adult Thoroughbreds received a continuous infusion of L-[ring-2H5]- phenylalanine during the study, the stable period for plasma isotope concentrations (60 min), resting periods (60 min), treadmill exercise (15 min) and recovery period (240 min). All horses were given 4 solutions (saline [Cont], 10% AA [10-AA], 10% Glu [10-Glu] and a mixture with 10% AA and 10% Glu [10-Mix]) over 120 min after exercise, and the Rs and Rd of muscle protein in the hindlimb measured.

RESULTS

The average Rs during the 75-120 min following administration of 10-Mix was significantly greater than for the other solutions (P<0.05). The second most effective solution was 10-AA, and there was no change in Rs after 10-Glu.

CONCLUSIONS

Administration of AA following exercise accelerated Rs in the hindlimb femoral region, and this effect was enhanced when combined with glucose, because of increasing insulin secretion or a decreased requirement for AA for energy.

POTENTIAL RELEVANCE

Further studies are required regarding the effect on muscle hypertrophy of supplementing amino acids and glucose in the feed of exercising horses.

Statin therapy reduces inflammatory markers in hypercholesterolemic patients with high baseline levels

AIM

Hypercholesterolemic patients with inflammation are at high risk for cardiovascular events. Statins exert anti-inflammatory action independent of their cholesterol-lowering action. This study sought to clarify whether statin therapy reduces inflammatory markers in hypercholesterolemic patients and to determine factors that predict the reduction in these markers.

METHODS

Fasting concentrations of lipoproteins and inflammatory markers were measured in 54 hypercholesterolemic patients, and age- and gender-matched healthy volunteers. Carotid atherosclerosis was determined by ultrasonography. Blood samples were also analyzed in hypercholesterolemic patients after 4 weeks of statin therapy.

RESULTS

The high-sensitivity C-reactive protein (hs-CRP) and serum amyloid A (SAA) protein concentrations did not differ between the two groups. Statin therapy reduced the median hs-CRP and SAA concentrations in hypercholesterolemic patients from 0.75 to 0.60 mg/L (p=0.05), and from 3.95 to 3.20 microg/mL (p=0.20), respectively. These reductions were significant for both markers, but only in subgroups with high baseline concentrations. Statins exhibited different results for hs-CRP and SAA in the presence of carotid atherosclerosis.

CONCLUSIONS

Statin therapy reduces inflammatory markers in hypercholesterolemic patients, and this anti-inflammatory action is limited to patients whose inflammatory markers are elevated at baseline.

Single administration of alpha-glucosidase inhibitors on endothelial function and incretin secretion in diabetic patients with coronary artery disease - Juntendo University trial: effects of miglitol on endothelial vascular reactivity in type 2 diabetic patients with coronary heart disease (J-MACH) -

BACKGROUND

Post-prandial hyperglycemia, hyperlipidemia, and endothelial dysfunction play an important role in the pathogenesis of atherosclerosis. Improvement in post-prandial hyperglycemia on alpha-glucosidase inhibitors (alpha-GIs) is associated with a risk reduction of cardiovascular diseases, but the post-prandial effects of alpha-GIs on endothelial function and incretin secretion in type 2 diabetic patients with coronary artery disease (CAD) remain unclear.

METHODS AND RESULTS

The post-prandial effects of a single administration of miglitol and voglibose on endothelial function and changing levels of glucose, insulin, lipids, glucagon-like peptide (GLP)-1, and gastric inhibitory polypeptide (GIP) were compared after a standard meal loading in 11 diabetic patients with CAD, using a placebo-controlled cross-over design. The changing levels of glucose, insulin and triglycerides at 60 min were significantly lower in the miglitol group than in the voglibose and placebo groups (all P<0.01). GLP-1 levels were significantly higher at 120 min (P<0.05) and GIP levels were significantly lower at 30 min and 60 min (P<0.05) in the miglitol group compared to other treatments. The reactive hyperemia duration at 120 min was significantly maintained in the miglitol group compared to the other groups.

CONCLUSIONS

A single administration of miglitol significantly improved post-prandial glucose/lipid metabolism, incretin secretion, and endothelial dysfunction in diabetic patients with CAD, suggesting that miglitol may be a useful anti-atherogenic agent (UMIN000002264).

Polyunsaturated fatty acid levels of serum and red blood cells in apparently healthy Japanese subjects living in an urban area

AIM

We assessed levels of polyunsaturated fatty acid (PUFA) in serum and red blood cells (RBCs) among groups stratified by generation and its clinical significance in Japanese subjects living in an urban area.

METHODS

We enrolled 200 apparently healthy Japanese (126 males, mean age: 50.3+/-9.2 years) living in an urban area. Levels of PUFA, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and dihomo-gamma-linolenic acid (DGLA) in serum and RBCs were measured for each generation (G1 <35y, G2 35y-<45y, G3 45y-<55y, G4 55y-<65y, G5>or=65y).

RESULTS

No significant differences in EPA, DHA, AA, or EPA/AA were observed between males and females. After dividing into generations, stepwise increases in EPA and DHA, but not DGLA or AA, were observed in serum (all p<0.0001). EPA/AA ratios were stepwisely increased in serum (mean: G1:0.26, G2:0.29, G3:0.43, G4:0.58, G5:0.68, p<0.0001) and RBCs (mean: G1:0.10, G2:0.09, G3:0.15, G4:0.20, G5:0.23, p<0.0001). Positive correlations of EPA (r=0.83), DHA (r=0.55), DGLA (r=0.54), AA (r=0.29), and EPA/AA (r=0.91) were demonstrated between serum and RBCs. In addition, a significant positive correlation between EPA/AA ratios and insulin sensitivity as well as a negative correlation between those ratios and insulin resistance were observed in subjects with metabolic syndrome.

CONCLUSION

Low levels of EPA/AA, which were associated with insulin resistance, were demonstrated in young Japanese adults living in an urban area.

Effects of phase III cardiac rehabilitation on mortality and cardiovascular events in elderly patients with stable coronary artery disease

BACKGROUND

Cardiac rehabilitation (CR) has numerous benefits, including reduction of mortality and cardiovascular events, in patients with coronary artery disease (CAD). However, the long-term effect of phase III CR in elderly patients with stable CAD is still unknown.

METHODS AND RESULTS

The 111 elderly male CAD patients (>or=65 years), including 37 subjects participating in supervised CR for 6 months and 74 age-matched controls, were analyzed. The patients were followed for up to 3,500 days, until the occurrence of death or 1 of the following major adverse cardiovascular events (MACE): cardiovascular death, acute coronary syndrome, refractory angina requiring revascularization, admission for congestive heart failure, or stroke. All-cause mortality tended to be lower in the CR group than in the Control group (14% vs 28%, P=0.081). The MACE incidence was significantly lower in the CR group than in the Control group (30% vs 62%, P=0.001). Multivariate Cox proportional hazard analysis showed that the MACE incidence was significantly lower in the CR group than in the Control group [adjusted hazard ratio 0.43 (95% confidence interval 0.20-0.91), P=0.027].

CONCLUSIONS

Phase III CR has the beneficial effect of reducing cardiovascular events even in elderly patients with stable CAD.

Circadian change of serum concentration of small dense LDL-cholesterol in type 2 diabetic patients

BACKGROUND

Type 2 diabetic patients have a higher risk of atherosclerosis than non-diabetic subjects. This difference may be attributable to increased levels of small dense low-density lipoprotein-cholesterol (sLDL-C) in diabetic patients. As the sLDL-C concentration is elevated in hypertriglyceridemia, which is exaggerated postprandially, we examined whether the sLDL-C level increases postprandially in type 2 diabetes.

METHODS

We obtained 7 blood samples (30min before and 2h after each meal, and at midnight) from 15 patients with diabetes and ten normal controls. Following the precipitation of very low-density lipoprotein and large buoyant LDL (bLDL) with heparin-Mg(2+), the sLDL-C concentration was determined as the cholesterol concentration by a homogeneous assay.

RESULTS

The fasting sLDL-C concentration was 60.3% higher in the diabetic patients than in the controls (1.01+/-0.21 vs. 0.63+/-0.21mmol/l, p<0.001). The sLDL-C concentrations in both groups were highest in the fasting state, decreased after breakfast, and remained low until midnight. The maximal reduction in the absolute sLDL-C concentration was 56.5% greater in the diabetic patients than in the controls (0.36+/-0.13 vs. 0.23+/-0.16mmol/l, p<0.05). Thus, the sLDL-C/bLDL-cholesterol (bLDL-C) ratio was reduced with increases in bLDL-C.

CONCLUSIONS

The sLDL-C concentration decreases postprandially in diabetes. This absolute reduction in sLDL-C may contribute to an acceleration of atherosclerosis in diabetic patients.

Effects of cardiac rehabilitation in patients with metabolic syndrome after coronary artery bypass grafting

BACKGROUND

Cardiac rehabilitation (CR) has numerous beneficial effects, including the modification of coronary risk factors and improvement of the prognosis, in patients with coronary artery disease (CAD). Limited data are available regarding the effects of CR on the physical status and risk factors in patients with metabolic syndrome (MetS) after coronary artery bypass grafting (CABG).

METHODS AND RESULTS

We enrolled 32 patients with MetS after CABG, who participated in a supervised CR program for 6 months. Metabolic parameters, blood chemistry, exercise tolerance, and muscle strength of the thigh were measured before and after CR. After CR: (1) the body mass index, waist circumference, and fat weight significantly decreased; (2) peak V O(2) and anaerobic threshold were significantly increased; (3) isokinetic peak torques of knee extensor and flexor muscles significantly increased; (4) metabolic scoring defined by the number of the modified Adult Treatment Panel criteria of the US National Cholesterol Education Program was significantly improved; (5) serum concentration of high-sensitivity C-reactive protein also significantly decreased.

CONCLUSIONS

These results suggest that CR might be useful for patients with MetS after CABG.