Triglyceride-Glucose Index Predicts Major Adverse Cardiovascular and Cerebrovascular Events in Patients with Atrial Fibrillation.

This study aimed to explore the relationship between the trajectory of the triglyceride-glucose (TyG) index and the occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) in patients with atrial fibrillation (AF).This prospective study included 1979 patients with AF, who were initially selected from the Kailuan study. Patients of AF were split into four groups according to the value of TyG index. The clinical endpoint was MACCE, including myocardial infarction and ischemic stroke. Cox proportional hazard models were employed to examine the hazard ratio (HR) and 95% confidence interval (CI) for MACCE in various trajectory groups.The mean age of all patients with AF was 67.65 ± 11.15 years, and 1752 (88.53%) were male. Over a median follow-up duration of 5.31 years, in total 227 MACCE were recorded. MACCE cumulative incidence in Quartile 4 (26.96%) was significantly higher than those in other quartiles (P = 0.023). Multivariate Cox proportional hazards regression analysis showed that a higher TyG index (Quartile 4) was significantly and positively linked to MACCE in patients with AF (P = 0.023, HR: 2.103; 95% CI: 1.107-3.994).The evaluated TyG index is significantly associated with an increased risk of MACCE in patients with AF.

Patients with Atrial Fibrillation are Unlikely to Benefit from Aspirin Monotherapy.

Background: Aspirin (ASA), the mainstay antiplatelet treatment in patients with cardiovascular disease (CVD), has been received by a considerable number of AF patients. This study sought to examine the association between ASA monotherapy and the risk of major adverse cardiac and cerebrovascular events (MACCE) in patients with atrial fibrillation (AF). Methods: A total of 850 patients with AF were identified from a community-based Kailuan study. All patients were assigned to two groups according to their medicine history: an aspirin therapy group (ASA group) (n = 174), and a non-aspirin therapy group (non-ASA group) (n = 676). The clinical endpoints are MACCE, including myocardial infarction (MI), ischemic stroke (IS), and hemorrhagic stroke (HS). Incidence curves for MACCE were plotted using the Kaplan-Meier method, and the Log rank test was used to assess the differences in incidence rates. The hazard ratios (HR) and 95% confidence intervals (CI) for MACCE were analyzed using Cox proportional-hazards analysis regression models. Results: During the 7.2-year follow-up, 30 MACCE occurred in the ASA group, and 101 in the non-ASA group, with a cumulative incidence of 19.88% vs 17.27%, P = 0.511; 3 cases of MI occurred in the ASA group, and 18 cases in the non-ASA group, with a cumulative incidence of 1.78% vs 2.90%, P = 0.305. Twenty-seven cases of IS occurred in the ASA group, and 84 cases in the non-ASA group, with a cumulative incidence of 1.78% vs 2.90%, P = 0.305. Eight cases of HS occurred in the ASA group, and 13 cases in the non-ASA group, with a cumulative incidence of 5.01% vs 2.34%, P = 0.045. Multivariate regression analysis showed that ASA therapy was not associated with MACCE (HR: 1.130, 95% CI: 0.747-1.710, P = 0.562). In addition, ASA therapy was not associated with IS (HR: 1.309, 95% CI: 0.843-2.034, P = 0.231). However, ASA therapy was significantly associated with HS (HR: 2.563, 95% CI: 1.024-6.418, P = 0.044). Conclusion: ASA monotherapy is not associated with a lower risk of ischemic events, while significantly associated with a higher risk of bleeding events. Patients with AF are unlikely to benefit from aspirin monotherapy.

Association of the triglyceride-glucose index with early-onset atherosclerotic cardiovascular disease events and all-cause mortality: a prospective cohort study.

BACKGROUND: The association between the triglyceride glucose (TyG) index and the risk of early-onset atherosclerotic cardiovascular disease (ASCVD) events or all-cause mortality in young and middle-aged people is not fully elucidated. METHODS: The present study included 64,489 young and middle-aged people who participated in the 2006 Kailuan Study physical examination. Multivariate Cox proportional hazards models and restricted cubic spline curves were used to assess the association of TyG index with early-onset ASCVD events and all-cause mortality. RESULTS: During a median of 11-year follow-up, 1984 (3.08%) participants experienced at least one ASCVD event and 1,392 (2.16%) participants experienced all-cause death. A higher TyG index was significantly associated with a higher risk of early-onset ASCVD events (HR: 1.61, 95% CI 1.38-1.89) and all-cause mortality (HR: 1.39, 95% CI 1.17-1.65), respectively. For each unit increase in TyG index, the risk of early-onset ASCVD events increased by 20%. In addition, there was a non-linear association between the TyG index and early-onset ASCVD events (P for non-linear < 0.01), and a linear association between TyG index and all-cause mortality (P for non-linear = 0.476). CONCLUSIONS: A higher TyG index is significantly associated with an increased incidence of early-onset ASCVD events and all-cause mortality in a young and middle-aged population from North China.

Triglyceride-glucose index predicts major adverse cardiovascular events in patients with chronic kidney disease.

BACKGROUND AND PURPOSE: Triglyceride-glucose (TyG) index has been regarded as a reliable surrogate marker of insulin resistance for predicting cardiovascular outcomes. The current study aimed to explore the associations between TyG index with major adverse cardiovascular events (MACE) in patients with chronic kidney disease (CKD). METHODS/PATIENTS: 13,517 patients with chronic kidney disease (CKD) from the Kailuan study were included. Patients were divided into quartiles according to the TyG index. The outcomes were MACE, including acute myocardial infarction (AMI) and ischemic stroke (IS). The association between TyG index and the risk of MACE was analyzed by Cox regression models. RESULTS: During 13.87-year follow-up, a total 1356 MACEs occurred. Multivariable Cox proportional-hazards analyses showed that a higher TyG index quartile was associated with an elevated risk of MACE. CONCLUSIONS: TyG index is significantly related to MACE in patients with CKD. TyG index can be regarded as a novel predictor of MACE for patients with CKD.

Lipoprotein(a) as a risk factor for atherosclerotic cardiovascular disease in patients in non-metropolitan areas of Brandenburg, Germany.

Background and aims: In the non-metropolitan region of Brandenburg (Germany), which is characterized by high rates of cardiovascular diseases and underserved medical care, there is a lack of awareness regarding lipoprotein(a) [Lp(a)] as a risk factor. In addition, data from patients with atherosclerotic cardiovascular disease (ASCVD) in diverse regional backgrounds, including the understudied Brandenburg cohort, and various healthcare statuses remain insufficient. Methods: In this WalkByLab study, Lp(a) levels were monitored in a non-metropolitan cohort (n = 850) in Brandenburg, Germany, comprising 533 patients at high cardiovascular risk and 317 healthy controls. Patients underwent a comprehensive angiological screening, which included blood serum analysis, assessment of medical and family history, cardiovascular risk, and disease status, and evaluation of lifestyle and quality of life. All parameters were evaluated with regard to two groups based on Lp(a) levels: low (<50 mg/dl) and high (≥50 mg/dl). Results: Brandenburg patients with cardiovascular diseases showed higher Lp(a) levels than healthy controls (24.2% vs. 14.8%, p = 0.001). Logistic regression analysis with different characteristics revealed that Lp(a) was an independent risk factor significantly associated with ASCVD (OR 2.26, 95% CI 1.32-3.95, p = 0.003). The high-Lp(a) group showed a higher proportion of patients with coronary artery disease, peripheral artery disease, or cerebrovascular disease compared to the low-Lp(a) group (50% vs. 36.8%; 57.7% vs. 45.8%; 17.6% vs. 9.2%; p = 0.004); also, a higher percentage of patients in the high-Lp(a) group had heart failure (72.8% vs. 53.2%, p = 0.014) and myocardial infarction (24.7% vs. 13.9%, p = 0.001). The high-Lp(a) group exhibited higher rates of statins (63.1% vs. 50.4%, p = 0.003), ezetimibe (14.8% vs. 5.5.%, p = 0.001), and beta-blockers (55.7% vs. 40.7%, p = 0.001) use. Lp(a) levels were found to be independent of physical activity or smoking behavior and did not change over time (12 months). Conclusions: Our study highlights the significance of elevated Lp(a) levels in Brandenburg cardiovascular patients and identifies them as an independent risk factor for ASCVD, which has implications for addressing cardiovascular health of non-metropolitan populations.

Leukocyte telomere length and mitochondrial DNA copy number associate with endothelial function in aging-related cardiovascular disease.

Background: We investigated the association between leukocyte telomere length, mitochondrial DNA copy number, and endothelial function in patients with aging-related cardiovascular disease (CVD). Methods: In total 430 patients with CVD and healthy persons were enrolled in the current study. Peripheral blood was drawn by routine venipuncture procedure. Plasma and peripheral blood mononuclear cells (PBMCs) were collected. Cell-free genomic DNA (cfDNA) and leukocytic genomic DNA (leuDNA) were extracted from plasma and PBMCs, respectively. Relative telomere length (TL) and mitochondrial DNA copy number (mtDNA-CN) were analyzed using quantitative polymerase chain reaction. Endothelial function was evaluated by measuring flow-mediated dilation (FMD). The correlation between TL of cfDNA (cf-TL), mtDNA-CN of cfDNA (cf-mtDNA), TL of leuDNA (leu-TL), mtDNA-CN of leuDNA (leu-mtDNA), age, and FMD were analyzed based on Spearman's rank correlation. The association between cf-TL, cf-mtDNA, leu-TL, leu-mtDNA, age, gender, and FMD were explored using multiple linear regression analysis. Results: cf-TL positively correlated with cf-mtDNA (r = 0.1834, P = 0.0273), and leu-TL positively correlated with leu-mtDNA (r = 0.1244, P = 0.0109). In addition, both leu-TL (r = 0.1489, P = 0.0022) and leu-mtDNA (r = 0.1929, P < 0.0001) positively correlated with FMD. In a multiple linear regression analysis model, both leu-TL (ß = 0.229, P = 0.002) and leu-mtDNA (ß = 0.198, P = 0.008) were positively associated with FMD. In contrast, age was inversely associated with FMD (ß = -0.426, P < 0.0001). Conclusion: TL positively correlates mtDNA-CN in both cfDNA and leuDNA. leu-TL and leu-mtDNA can be regarded as novel biomarkers of endothelial dysfunction.

Atrial fibrillation increases the risk of new-onset myocardial infarction amongst working-age population: a propensity-matched study.

OBJECTIVE: The aim of this study was to investigate the association between atrial fibrillation (AF) and new-onset myocardial infarction (MI) among a working-age population in an industrial city of North China. METHODS: In total 77,670 participants aged under 60 years were selected for this cohort study. Participants were divided into an AF group (n = 121) and a non-AF group (n = 74,565) based on their medical histories. Thereafter, 121 participants from the AF group were propensity-matched with 363 participants from the non-AF group. All participants were followed up from June 2006 to December 2020; new-onset MI was regarded as the endpoint of this study. Multivariate Cox proportional hazards regression analysis models were designed to analyze the correlation between AF and new-onset MI. RESULTS: During the 14-year follow-up, eight cases of new-onset MI were documented in the AF group, while five cases were documented in the non-AF group. The cumulative incidence of new-onset MI in the AF group (7.40%) was markedly higher than in the non-AF group (1.41%; p < 0.001). Atrial fibrillation was associated with an increased risk of new-onset MI in both univariate analysis (hazard ratio: 5.202, 95% confidence interval [CI]: 1.700-15.913) and multivariable-adjusted analysis (hazard ratio: 5.335, 95% CI: 1.683-16.910). CONCLUSION: Atrial fibrillation increased the risk of new-onset MI amongst working-age individuals in an industrial city of North China.

Autophagy-related genes analysis reveals potential biomarkers for prediction of the impaired walking capacity of peripheral arterial disease.

BACKGROUND: The role of autophagy and autophagy-related genes in peripheral arterial disease (PAD) remains unknown and may be of diagnostic and prognostic value. The aim of this study is to investigate the relationship between autophagy and PAD, and identify potential diagnostic or prognostic biomarkers for medical practice. METHODS: Differentially expressed autophagy-related genes in PAD were explored from GSE57691 and validated in our WalkByLab registry participants by quantitative real-time polymerase chain reaction (qRT-PCR). The level of autophagy in peripheral blood mononuclear cells (PBMCs) of WalkByLab participants was assessed by analyzing autophagic marker proteins (beclin-1, P62, LC3B). Single sample gene set enrichment analysis (ssGSEA) was used to evaluate the immune microenvironment within the artery wall of PAD patients and healthy persons. Chemokine antibody array and enzyme-linked immunosorbent assay were used to assess the chemokines in participants' plasma. Treadmill testing with Gardner protocol was used to evaluate participants' walking capacity. Pain-free walking distance, maximum walking distance, and walking time were recorded. Finally, a nomogram model based on logistic regression was built to predict impaired walking performance. RESULTS: A total of 20 relevant autophagy-related genes were identified, and these genes were confirmed to be expressed at low levels in our PAD participants. Western blotting demonstrated that the expression of autophagic marker proteins beclin-1 and LC3BII were significantly reduced in PAD patients' PBMCs. ssGSEA revealed that most of the autophagy-related genes were strongly correlated with immune function, with the largest number of associated genes showing interaction between cytokine-and-cytokine receptors (CCR). In this context, the chemokines growth-related oncogene (GRO) and neutrophil activating protein2 (NAP2) are highly expressed in the plasma of WalkByLab PAD patients and were significantly negatively correlated with the walking distance assessed by Gardner treadmill testing. Finally, the plasma NAP2 level (AUC: 0.743) and derived nomogram model (AUC: 0.860) has a strong predictive potential to identify a poor walking capacity. CONCLUSIONS: Overall, these data highlight both the important role of autophagy and autophagy-related genes in PAD and link them to vascular inflammation (expression of chemokines). In particular, chemokine NAP2 emerged as a novel biomarker that can be used to predict the impaired walking capacity in PAD patients.

Atrial fibrillation is an independent risk factor for new-onset myocardial infarction: a prospective study.

BACKGROUND: Atrial fibrillation (AF) and myocardial infarction (MI) share common cardiovascular risk factors, therefore coexistence of AF and MI is very common, in addition, both AF and MI aggravate and exacerbate each other through multiple pathological processes. The aim of this study is to investigate whether AF increases the risk of new-onset MI. METHODS: In total 171,086 participants from an industrial city in North China were selected and enrolled in this prospective cohort study, participants were divided into the AF group or the non-AF group according to their medical history. 1542 participants from the AF group were propensity-matched with 4626 participants from the non-AF group. All the participants were followed up every 2 years from June 2006 to December 2020, the median follow-up was 14.25 years and the endpoint of this study was new-onset MI. The association between AF and new-onset MI was analysed by using both univariate and multivariate Cox proportional hazards regression analysis. RESULTS: New-onset MI was documented in 56 cases from the AF group and 98 cases from the non-AF group, respectively, the cumulative incidence of new-onset MI in the AF group (3.73%) was significantly higher than that in the non-AF group (2.23%) (p < 0.01). In a univariate analysis, AF was associated with an increased risk of new-onset MI (hazard ratio: 1.73, 95% confidence interval: 1.24-2.40), in two multivariable-adjusted analyses, AF was still associated with an increased risk of new-onset MI (hazard ratio: 1.78, 95% confidence interval, 1.28-2.47). CONCLUSIONS: AF is an independent risk factor for new-onset MI in an industrial population of North China.

The effect of prophylactic balloon occlusion in patients with placenta accreta spectrum: a Bayesian network meta-analysis.

OBJECTIVES: Placenta accreta spectrum (PAS) can induce severe life-threatening obstetric hemorrhage. Herein, we conducted a Bayesian network meta-analysis of previous studies to evaluate the relative benefits of different prophylactic balloon occlusion (PBO) procedures. METHODS: PubMed, Embase, Cochrane Library, and Web of Science were searched from inception to July 2021. Blood loss volume, blood transfusion volume, and hysterectomy rate were regarded as the primary endpoints. The data were pooled using a Bayesian network and traditional pairwise meta-analysis. RESULTS: Fifty-nine articles with a total sample size of 5150 patients were included. Compared with no PBO (non-PBO) intervention, PBO of the abdominal aorta (PBOAA, mean difference(MD) - 1.02, 95% credible interval (CrI) - 1.4 to - 0.67), common iliac artery (PBOCIA, MD - 0.84; 95%CrI - 1.36 to - 0.06) and internal iliac artery (PBOIIA, MD - 0.42; 95%CrI - 0.72 to - 0.13) significantly lowered blood loss volume, with PBOAA being more effective than PBOIIA (MD - 0.60; 95%CrI - 1.05 to - 0.17). PBOAA and PBOIIA also significantly decreased blood loss volume (MD - 2.33; 95%CrI - 3.74 to - 0.94, MD - 1.57; 95%CrI - 2.77 to - 0.47 respectively) and hysterectomy rate (OR 0.31; 95%CrI 0.16 to 0.54, OR 0.53; 95%CrI 0.29 to 0.92 respectively). PBOAA has the highest probability of being more effective in reducing the blood loss volume, blood transfusion volume, and hysterectomy rate. CONCLUSIONS: Performing PBOAA, PBOCIA, or PBOIIA in PAS patients is an effective way to minimize blood loss volume, while PBOAA and PBOIIA also reduce blood transfusion volume and hysterectomy rate. PBOAA is a notably more effective strategy to reduce blood loss volume than PBOIIA. KEY POINTS: • PBOAA, PBOCIA, and PBOIIA procedures can significantly reduce the blood loss volume compared to non-PBO intervention in PAS patients, of which PBOAA was more effective than the PBOIIA procedure. • PBOAA and PBOIIA could significantly reduce the blood transfusion volume and hysterectomy rate in contrast to the non-PBO intervention in patients with PAS. • According to our statistical treatment ranking, PBOAA was statistically superior in reducing blood transfusion volume, blood transfusion volume, and hysterectomy rate than other PBO procedures.

Angiotensin receptor-neprilysin inhibitor improves coronary collateral perfusion.

Background: We investigated the pleiotropic effects of an angiotensin receptor-neprilysin inhibitor (ARNi) on collateral-dependent myocardial perfusion in a rat model of coronary arteriogenesis, and performed comprehensive analyses to uncover the underlying molecular mechanisms. Methods: A rat model of coronary arteriogenesis was established by implanting an inflatable occluder on the left anterior descending coronary artery followed by a 7-day repetitive occlusion procedure (ROP). Coronary collateral perfusion was measured by using a myocardial particle infusion technique. The putative ARNi-induced pro-arteriogenic effects were further investigated and compared with an angiotensin-converting enzyme inhibitor (ACEi). Expression of the membrane receptors and key enzymes in the natriuretic peptide system (NPS), renin-angiotensin-aldosterone system (RAAS) and kallikrein-kinin system (KKS) were analyzed by quantitative polymerase chain reaction (qPCR) and immunoblot assay, respectively. Protein levels of pro-arteriogenic cytokines were measured by enzyme-linked immunosorbent assay, and mitochondrial DNA copy number was assessed by qPCR due to their roles in arteriogenesis. Furthermore, murine heart endothelial cells (MHEC5-T) were treated with a neprilysin inhibitor (NEPi) alone, or in combination with bradykinin receptor antagonists. MHEC5-T proliferation was analyzed by colorimetric assay. Results: The in vivo study showed that ARNis markedly improved coronary collateral perfusion, regulated the gene expression of KKS, and increased the concentrations of relevant pro-arteriogenic cytokines. The in vitro study demonstrated that NEPis significantly promoted MHEC5-T proliferation, which was diminished by bradykinin receptor antagonists. Conclusion: ARNis improve coronary collateral perfusion and exert pro-arteriogenic effects via the bradykinin receptor signaling pathway.

Angiotensin-converting enzyme inhibitors stimulate cerebral arteriogenesis.

AIM: Arteriogenesis constitutes the most efficient endogenous rescue mechanism in cases of cerebral ischaemia. The aim of this work was to investigate whether angiotensin-converting enzyme inhibitors (ACEi) stimulates, and angiotensin II receptor type 1 blockers (ARB) inhibits cerebral collateral growth by applying a three-vessel occlusion (3-VO) model in rat. METHODS: Cerebral collateral growth was measured post 3-VO (1) by assessing blood flow using the cerebrovascular reserve capacity (CVRC) technique, and (2) by assessing vessel diameters in the posterior cerebral artery (PCA) via the evaluation of latex angiographies. A stimulatory effect on arteriogenesis was investigated for ACEi administration ± bradykinin receptor 1 (B1R) and 2 (B2R) blockers, and an inhibitory effect was analysed for ARB administration. Results were validated by immunohistochemical analysis and mechanistic data were collected by human umbilical vein endothelial cell (HUVEC) viability or scratch assay and monocyte (THP-1) migration assay. RESULTS: An inhibitory effect of ARB on arteriogenesis could not be demonstrated. However, collateral growth measurements demonstrated a significantly increased CVRC and PCA diameters in the ACEi group. ACEi stimulates cell viability and migration, which could be partially reduced by additional administration of bradykinin receptor 1 inhibitor (B1Ri). ACEi inhibits the degradation of pro-arteriogenic bradykinin derivatives, but combined ACEi + B1Ri + B1Ri (BRB) treatment did not reverse the stimulatory effect. Yet, co-administration of ACEi + BRB enhances arteriogenesis and cell migration. CONCLUSION: We demonstrate a potent stimulatory effect of ACEi on cerebral arteriogenesis in rats, presumable via B1R. However, results imply a pleiotropic and compensatory effect of ACEi on bradykinin receptor-stimulated arteriogenesis.

Effect of ACEI and ARB treatment on nitric oxide-dependent endothelial function.

Background: Angiotensin-converting-enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB) are widely used as a first-line therapy for the treatment of cardiovascular disease. Here, ACEI modulate the bradykinin receptor (BDKRB1 and BDKRB2) system and NO-dependent endothelial function, thus determining cardiovascular health and regenerative arteriogenesis. The current study aims at evaluating nitric oxide-dependent endothelial function, and gene expression of bradykinin receptors in peripheral blood mononuclear cells (PBMC) from patients with ACEI or ARB treatment. Patients and methods: The WalkByLab has been established to screen cardiovascular patients for peripheral artery disease and coronary artery disease. In total 177 patients from WalkByLab with heterogenous disease and risk status were randomly selected, divided according to their medication history into the following groups: 1. ACEI group, 2. ARB group or 3. non-ACE/ARB group. Total plasma nitrite/nitrate (NO) levels were measured, endothelial function was evaluated by assessing flow meditated dilation (FMD). PBMC were isolated from peripheral whole blood, and gene expression (qRT-PCR) of bradykinin receptors and angiotensin converting enzyme were assessed. Results: Plasma total NO concentration in the ACEI group (24.66±16.28, µmol/l) was increased as compared to the ARB group (18.57±11.58, µmol/l, P=0.0046) and non-ACE/ARB group (16.83±8.64, µmol/l, P=0.0127) in patients between 40 to 90 years of age. However, FMD values (%) in the ACEI group (7.07±2.40, %) were similar as compared to the ARB (6.35±2.13, %) and non-ACE/ARB group (6.51±2.15, %), but significantly negatively correlated with age. Interestingly, BDKRB1 mRNA level was significantly higher and BDKRB2 mRNA level lower in the ACEI group (BDKRB1 3.88-fold±1.05, BDKRB2 0.22-fold±0.04) as compared to the non-ACE/ARB group (BDKRB1 1.00-fold±0.39, P<0.0001, BDKRB2 1.00-fold±0.45, P=0.0136). Conclusions: ACEI treatment enhances total nitrite/nitrate concentration, furthermore, upregulates BDKRB1 in PBMC, but downregulates BDKRB2 mRNA expression. FMD is a strong determinant of vascular aging and is sensitive to underlying heterogenous cardiovascular diseases.

Influences of Pretreatment of Carbon on Performance of Carbon Supported Pd Nanocatalyst for Nitrobenzene Hydrogenation.

We in this study prepared carbon supported Pd (Pd/C) nanocatalyst using pretreated carbon by different concentrations of hydrochloric acid, nitric acid, tartaric acid and hydrogen peroxide, respectively. The nanocatalyst was used for hydrogenation of nitrobenzene. The catalytic activity and microstructure of Pd/C catalyst were characterized by High Performance Liquid Chromatography (HPLC), scanning electron microscope (SEM), High power transmission electron microscopy (HTEM) and X-ray Diffraction (XRD). Results showed that the order of catalytic activity was as follows: Pd/C (C4H6O6) < Pd/C (HCI) < Pd/C (HNO3) < Pd/C (H2O2). The values for specific surface area, pore size and pore volume all decreased after pretreatment by HCl and HNO3, and presented a slight increase after pretreatment with H2O2. The dispersion performance of particles in Pd/C catalysts obtained with 25% hydrogen peroxide pretreatment was better and these particles' mean size was 8.0 nm. Pd crystallization degree for catalysts was lower after hydrogen peroxide pretreatment, and the crystalline grains were smaller.