[Targeted suppression of miRNA-21 inhibit K562 cells growth through PTEN-PI3K/AKT signaling pathway]

Objective: To investigate the K562 cells biological function and related molecular changes in PTEN-PI3K/AKT signaling pathway of leukemia K562 cells by inhibiting the miRNA-21 expression to explore its pathogenesis of leukemia. Methods: The chemical synthetic miRNA-21 inhibitor was transfered into K562 cells by electrotransfection. RT-PCR was used to detect the miRNA-21 expression changes. Cell proliferation and apoptosis were determined by using MTT and flow cytometry. Western-blot were used to detect the protein expression changes of PTEN, PI3K and p-AKT respectively. Results: The relative expression of miRNA-21 in experimental group was (8.070 ± 5.138)% at 24 hours, which was lower than control groups (P<0.05). The apoptotic rate of (13.370±0.250)% at 24 hours in experimental group was obviously higher than control groups. The cellular proliferation were significantly different at 24 hours. The proliferation inhibition rate was (8.1±0.9)% at 24 hours, which was up to (43.1±2.1)% at 60 hours, but the control groups showed no difference. K562 cell proliferation significantly decreased, while cell apoptosis markedly increased by inhibiting miRNA-21 expression (P<0.01). Western-blot analysis revealed up-regulation of PTEN and down-regulation of PI3K and p-AKT protein expressions after successfully suppressed miRNA-21 expression (P<0.01). Conclusion: Inhibiting miRNA-21 expression in K562 cell could suppress the PI3K/AKT pathway by up-regulation of PTEN expression and promote cell antiproliferative and pro-apoptosis effects.

Validation of a new simple scale to measure symptoms in heart failure from traditional Chinese medicine view: a cross-sectional questionnaire study

Background

Current clinical practices used to functionally classify heart failure (HF) are time-consuming, expensive, or require complex calculations. This study aimed to design an inquiry list from the perspective of traditional Chinese medicine (TCM) that could be used in routine clinical practice to resolve these problems.

Methods

The severity of documented HF in 115 patients was classified according to their performance in maximal exercise tests into New York Heart Association (NYHA) functional classification (FC) II or NYHA FC III. Concomitantly, the patients were assessed using the new TCM inquiry list and two validated quality of life questionnaires, namely, the Short Form 36 (SF-36) generic scale and the Minnesota Living with Heart Failure Questionnaire (MLHFQ). Factor analysis was applied to extract the core factors from the responses to the items in TCM inquiry list; logistic regression analysis was then used to predict the severity of HF according to the extracted factors.

Results

The TCM inquiry list showed moderate levels of correlation with the physical and emotional components of the SF-36 and the MLHFQ, and predicted the functional class of HF patients reliably using logistic regression analysis, with a correct prediction rate with 64.3 %. Factor analysis of the TCM inquiry list extracted five core factors, namely, Qi Depression, Heart Qi Vacuity and Blood Stasis, Heart Blood Vacuity, Dual Qi-Blood Vacuity, and Yang Vacuity, from the list, which aligned with the perspective of TCM as it relates to the pattern of HF. The correct prediction rate rose to 70.4 % when Dual Qi-Blood Vacuity was combined with the MLHFQ. The excessive false-negative rate is a problem associated with the TCM inquiry list.

Conclusions

The TCM inquiry list is a simple scale and similar to patient-reported subjective measures of quality of life in HF, and may help to classify patients into NYHA FC II or NYHA FC III. Factor 4 addresses dizziness, dizzy vision and general weakness, which are critical parameters that distinguish between NYHA FC II and NYHA FC III. Incorporating these three items into the management of HF may help to classify patients from a functional perspective.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1306-7) contains supplementary material, which is available to authorized users.

Estimating systemic fibrosis by combining galectin-3 and ST2 provides powerful risk stratification value for patients after acute decompensated heart failure

BACKGROUND

Two fibrosis biomarkers, galectin-3 (Gal-3) and suppression of tumorigenicity 2 (ST2), provide prognostic value additive to natriuretic peptides and traditional risk factors in patients with heart failure (HF). However, it is to be investigated whether their combined measurement before discharge provides incremental risk stratification for patients after acute HF.

METHODS

A total of 344 patients with acute HF were analyzed with Gal-3, and ST2 measured. Patients were prospectively followed for 3.7 ± 1.3 years for deaths, and composite events (death/HF-related re-hospitalizations).

RESULTS

The levels of Gal-3 and ST2 were only slightly related (r = 0.20, p < 0.001). The medians of Gal-3 and ST2 were 18 ng/mL and 32.4 ng/mL, respectively. These biomarkers compensated each other and characterized patients with different risk factors. According to the cutoff at median values, patients were separated into four subgroups based on high and low Gal-3 (HG and LG, respectively) and ST2 levels (HS and LS, respectively). Kaplan-Meier survival curves showed that HGHS powerfully identified patients at risk of mortality (Log rank = 21.27, p < 0.001). In multivariable analysis, combined log(Gal-3) and log(ST2) was an in-dependent predictor. For composite events, Kaplan-Meier survival curves showed a lower event- -free survival rate in the HGHS subgroup compared to others (Log rank = 34.62, p < 0.001; HGHS vs. HGLS, Log rank = 4.00, p = 0.045). In multivariable analysis, combined log(Gal-3) and log(ST2) was also an independent predictor.

CONCLUSIONS

Combination of biomarkers involving heterogeneous fibrosis pathways may identify patients with high systemic fibrosis, providing powerful risk stratification value.

Factors Associated With Inadequate Effectiveness of a Multidisciplinary Disease Management Program in Heart Failure Patients Stratified by Galectin 3 Level

OBJECTIVE

This study investigated whether multidisciplinary disease management programs (MDPs) exert the same effects in heart failure (HF) patients across risk levels stratified by galectin-3 (Gal-3) level and what factors are associated with inadequate effectiveness of MDP.

METHODS

We used a longitudinal follow-up design based on a previous randomized trial. A total of 355 stabilized hospitalized HF patients were enrolled. The effects of MDP on death and HF-related rehospitalization were analyzed according to Gal-3 levels.

RESULTS

During the 4-year follow-up, Gal-3 levels predicted mortality and composite events ( p < .001). Multivariable analysis demonstrated the event-lowering effect of MDP (hazard ratio [HR] = 0.49, p = .001 for death and HR = 0.50, p < .001 for composite events). However, the effect of MDP was inadequate for those with high Gal-3 levels (≥17.9 ng/ml), whose 4-year composite event rate was 43% in the MDP arm. Further analysis showed that, in patients with Gal-3 ≥ 17.9 ng/ml, the independent factors associated with a high composite event rate were no MDP, older age, worse New York Heart Association functional class, no angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker use, higher predischarge natriuretic peptide levels, and wider QRS complexes.

CONCLUSIONS

The effectiveness of MDP for HF patients at high risk was inadequate. Our findings identified the characteristics of these MDP nonresponders. Better integration of advanced care plans based on strategies guided by Gal-3 level is needed to improve care quality.

Electricity production from municipal solid waste using microbial fuel cells

The organic content of municipal solid waste has long been an attractive source of renewable energy, mainly as a solid fuel in waste-to-energy plants. This study focuses on the potential to use microbial fuel cells to convert municipal solid waste organics into energy using various operational conditions. The results showed that two-chamber microbial fuel cells with carbon felt and carbon felt allocation had a higher maximal power density (20.12 and 30.47 mW m(-2) for 1.5 and 4 L, respectively) than those of other electrode plate allocations. Most two-chamber microbial fuel cells (1.5 and 4 L) had a higher maximal power density than single-chamber ones with corresponding electrode plate allocations. Municipal solid waste with alkali hydrolysis pre-treatment and K3Fe(CN)6 as an electron acceptor improved the maximal power density to 1817.88 mW m(-2) (~0.49% coulomb efficiency, from 0.05-0.49%). The maximal power density from experiments using individual 1.5 and 4 L two-chamber microbial fuel cells, and serial and parallel connections of 1.5 and 4 L two-chamber microbial fuel cells, was found to be in the order of individual 4 L (30.47 mW m(-2)) > serial connection of 1.5 and 4 L (27.75) > individual 1.5 L (20.12) > parallel connection of 1.5 and 4 L (17.04) two-chamber microbial fuel cells . The power density using municipal solid waste microbial fuel cells was compared with information in the literature and discussed.

Myocardial triglyceride content at 3 T cardiovascular magnetic resonance and left ventricular systolic function: a cross-sectional study in patients hospitalized with acute heart failure

BACKGROUND

Increased myocardial triglyceride (TG) content has been recognized as a risk factor for cardiovascular disease. However, its relation with cardiac function in patients on recovery from acute heart failure (HF) remains unclear. In this cross-sectional study, we sought to investigate the association between myocardial TG content measured on magnetic resonance spectroscopy ((1)H-MRS) and left ventricular (LV) function assessed on cardiovascular magnetic resonance (CMR) in patients who were hospitalized with HF.

METHODS

A total of 50 patients who were discharged after hospitalization for acute HF and 21 age- and sex-matched controls were included in the study. Myocardial TG content and LV parameters (function and mass) were measured on a 3.0 T MR scanner. Fatty acid (FA) and unsaturated fatty acid (UFA) content was normalized against water (W) using the LC-Model algorithm. The patient population was dichotomized according to the left ventricular ejection fraction (LVEF, <50% or ≥ 50%).

RESULTS

H-MRS data were available for 48 patients and 21 controls. Of the 48 patients, 25 had a LVEF <50% (mean, 31.2%), whereas the remaining 23 had a normal LVEF (mean, 60.2%). Myocardial UFA/W ratio was found to differ significantly in patients with low LVEF, normal LVEF, and controls (0.79% vs. 0.21% vs. 0.14%, respectively, p = 0.02). The myocardial UFA/TG ratio was associated with LV mass (r = 0.39, p < 0.001) and modestly related to LV end-diastolic volume (LVEDV; r = 0.24, p = 0.039). We also identified negative correlations of the myocardial FA/TG ratio with both LV mass (r = -0.39, p < 0.001) and LVEDV (r = -0.24, p = 0.039).

CONCLUSIONS

As compared with controls, patients who were discharged after hospitalization for acute HF had increased myocardial UFA content; furthermore, UFA was inversely related with LVEF, LV mass and, to a lesser extent, LVEDV. Our study may stimulate further research on the measure of myocardial UFA content by (1)H-MRS for outcome prediction.

TRIAL REGISTRATION

ClinicalTrial.gov: NCT02378402 . Registered 27/02/2015.

Quantitative trait locus analysis of leaf morphological characters, yield-related traits, and secondary metabolite contents in Eucommia ulmoides

Eucommia ulmoides is cultivated for the production of eucommia rubber and Chinese herbal drugs. Molecular breeding methods, such as marker-assisted selection (MAS), have the potential to improve the efficiency of E. ulmoides breeding. Quantitative trait locus (QTL) analysis was applied to identify marker-trait associations for E. ulmoides using an F1 mapping population of 152 individuals derived from a cross between the wild genotype Xiaoye and the cultivar Qinzhong No. 1. A total of 78 QTLs were identified for 12 leaf traits involving morphology, yield, and secondary metabolites. Phenotypic variance explained by individual QTLs ranged from 10.4 to 53.3%. Fifteen QTL clusters, each harboring loci controlling at least two leaf traits, were detected across nine linkage groups. Co-location of these QTLs may be due to pleiotropy or linkage. Three main QTL regions for secondary metabolites were consistently identified each year. QTL information from this study furthers our understanding of the genetic architecture of these economically important traits and of MAS in E. ulmoides breeding.

Genetic diversity and relationships among Chinese Eucommia ulmoides cultivars revealed by sequence-related amplified polymorphism, amplified fragment length polymorphism, and inter-simple sequence repeat markers

Sequence-related amplified polymorphism (SRAP), amplified fragment length polymorphism (AFLP), and inter-simple sequence repeat (ISSR) markers were used to estimate the genetic diversity and relationships among Eucommia ulmoides cultivars in China. A total of 240, 192, and 150 DNA fragments were detected by 10 SRAP primer combinations, 10 AFLP primer combinations, and 10 ISSR primers, among which 89.2, 65.1, and 88.0% of the fragments were polymorphic, respectively. Cluster analysis revealed that Qinzhong No. 3, Xiaoyeci, Qinzhong No. 1, and Qinzhong No. 2 formed independent clusters. The other 15 cultivars exhibited two clusters. The results of this study will help in the selection of parents for both genome mapping and crossbreeding purposes.

Evidence of bird dropping masquerading by a spider to avoid predators

Masquerading comes at various costs and benefits. The principal benefit being the avoidance of predators. The orb-web spider Cyclosa ginnaga has a silver body and adds a white discoid-shaped silk decoration to its web. The size, shape and colour of C. ginnaga's body resemble, when viewed by the human eye against its decoration, a bird dropping. We therefore hypothesized that their body colouration might combine with its web decoration to form a bird dropping masquerade to protect it from predators. We measured the spectral reflectance of: (i) the spider's body, (ii) the web decoration, and (iii) bird droppings, in the field against a natural background and found that the colour of the spider bodies and decorations were indistinguishable from each other and from bird droppings when viewed by hymentopteran predators. We monitored the predatory attacks on C. ginnaga when the spider's body and/or its decorations were blackened and found that predator attack probabilities were greater when only the decorations were blackened. Accordingly, we concluded that C. ginnaga's decoration and body colouration forms a bird dropping masquerade, which reduces its probability of predation.

Plasma P-selectin predicts long-term cardiovascular events in hospitalized patients with suspected coronary artery disease and preserved left ventricular function: a 10-year follow-up study

BACKGROUND

A variety of biomarkers have been investigated on their values to predict cardiovascular outcomes, such as high-sensitivity C-reactive protein (hs-CRP), fibrinogen, troponin-I (TnI), and soluble P-selectin (sP-sel). By a design of head-to-head comparison, this study sought to figure out the long-term prognostic values of these parameters in patients hospitalized with suspected coronary artery disease.

METHODS

A total of 170 patients hospitalized with suspected coronary artery disease were enrolled and followed up for an average of 10 years. sP-sel, hs-CRP, TnI, and fibrinogen levels were measured. During the follow-up period, cardiac events were recorded including cardiac death, non-fatal myocardial infarction, and acute coronary syndromes with hospitalization.

RESULTS

For all 170 patients, with a median follow-up time of 9.86 ± 3.87 years, no parameter was able to significantly predict the occurrence of cardiac events. In subgroup analysis, an sP-sel of ≥ 63.5 ng/ml significantly predicted the development of all composite cardiac events only in patients with a left ventricular ejection fraction > 50% (n = 94, p = 0.04). However, the levels of hs-CRP, TnI, and fibrinogen did not have significant predictive values. Multivariate analysis also demonstrated the independent predictive value of sP-sel on all cardiac events (hazard ratio = 5.82, p = 0.02). All parameters, including sP-sel, could not demonstrate prognostic values in patients with a left ventricular ejection fraction ≤ 50% (n = 76).

CONCLUSIONS

In this 10-year long-term follow-up study, sP-sel was demonstrated to have prognostic values in predicting the cardiac events in patients with preserved left ventricular systolic function.

Efficacy of telbivudine on interruption of hepatitis B virus vertical transmission: a meta-analysis

BACKGROUND AND OBJECTIVES

Hepatitis B virus (HBV) infection is one of the most common infections in the world. Vertical transmission is the main reason for the continued endemic infection rates, at least in Asia. This study aimed to investigate the efficacy of telbivudine on mother-to-child transmission (MTCT) interruption.

METHODS

Studies up to April 2012 were collected by searching Pubmed, EMBASE, the Cochrane Library, EBM Review, WangFang Database and China National Knowledge Infrastructure. Serum hepatitis B surface antigen (HBsAg) and HBV DNA in newborns and infants, maternal HBV DNA negative conversion and alanine trans.aminase (ALT) normalization and adverse events were analyzed.

RESULTS

Seven clinical trials involving 644 pregnant women were included in this meta-analysis. Telbivudine resulted in lower HBsAg and HBV DNA seroprevalence in newborns and infants. When maternal viral load prior to delivery was higher than 103copies/mL, HBsAg or HBV DNA positivity had no statistical difference.

CONCLUSIONS

Telbivudine treatment has efficacy and safety on MTCT interruption during late pregnancy. In addition, we demonstrated benefit of telbivudine for mothers in terms of HBV DNA negative conversion and ALT normalization. Telbivudine treatment at the end of pregnancy should be considered in women with high viral load.

Timing of gangrene tissue debridement after autologous bone marrow cell implantation in patients with superficial femoral arterial occlusion: preliminary experiences

AIM

Although implantation of bone marrow mononuclear cells (BMI) was shown to improve outcomes in patients with severe peripheral arterial occlusive disease (PAOD), little experience has been reported in patients with an arterial occlusion level above the knee, ischemic gangrene, and high cardiovascular risk. This study sought to investigate the timing of gangrene tissue debridement and the safety of BMI in these patients.

METHODS

Six "no-option" PAOD patients were enrolled with an arterial occlusion level above the knee, ischemic gangrene, and 3 systemic diseases related to a high cardiovascular risk. The ischemic status was evaluated by measuring the ankle-brachial index (ABI), transcutaneous oxygen pressure (TcPO2), and wound healing after BMI.

RESULTS

All patients safely underwent the procedures with intravenous general anesthesia by titrating propofol. Major lower extremity amputation, minor debridement amputation, and debridement surgery were performed in 2 (33.3%), 1 (16.7%), and 2 (33.3%) patients, respectively, 3.1 2.8 months after BMI. Compared to the amputation group (N=3), the salvage group (N=3) had a significantly higher baseline ABI (P=0.02) and a shorter distance between the gangrene site and arterial occlusion site (P=0.01). In the 3 patients who underwent debridement, ABI and TcPO2 significantly improved 1 month after BMI, and gangrenous tissues were debrided 3.8 ± 3.6 (range, 1~8) months after BMI with complete healing within 1 month.

CONCLUSION

Autologous BMI therapy is safe in patients at high cardiovascular risk with an arterial occlusion level above the knee and ischemic gangrene. Effective predictors of BMI include the baseline ABI and distance to the ischemia. Gangrene tissue should be debrided at least 1 month after BMI.

Edema index-guided disease management improves 6-month outcomes of patients with acute heart failure

The efficacy of heart failure (HF) management programs is compromised by the challenge of early identification of patients at imminent risk. Segmental multifrequency bioelectrical impedance analysis can generate an "edema index" (EI) as a surrogate for the body fluid status. In this study, we tested whether integration of EI-guided management improved the 6-month outcomes of HF patients under multidisciplinary care. In total, 159 patients with acute HF were randomized into control, case management (CM), and EI-guided CM (EI) groups (n = 53 in each group). In the EI group, a management algorithm was designed based on the measured EI. The analyzed endpoints included HF-related and all cause-related events during the 6-month follow-up period. In the 6 months, there were 11 (6.9%) deaths, 19 (11.9%) HF-related rehospitalizations, and 45 (28.3%) all-cause-related rehospitalizations. Compared to the control (26.4%) and CM groups (15.1%), the EI group had a lower rate of HF-related death and rehospitalization (3.8%, P = 0.004). Multivariate analysis revealed that EI-guided management was an independent predictor of a lower HF-related event rate (hazard ratio = 0.15, 95%CI = 0.03~0.66, P = 0.012). Patients with a higher pre-discharge EI were older, had lower blood albumin and hemoglobin levels, and had a higher functional class and incidences of diabetes mellitus and chronic kidney disease. An increase in the pre-discharge EI by 0.001 increased the HF-related event rate by 6% (P = 0.002). Use of EI-guided management lowered this risk (P = 0.03). In conclusion, an EI-based HF management program demonstrated an event-lowering effect superior to traditional nurse-led multidisciplinary care in 6 months after an acute HF episode.

Effects of spiked metals on the MSW anaerobic digestion

This study aimed to investigate the effects of eight metals on the anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) in bioreactors. Anaerobic bioreactors containing 200 mL MSW mixed completely with 200 m L sludge seeding. Ca and K (0, 1000, 2000 and 6,000 mg L(-1)) and Cr, Ni, Zn, Co, Mo and W (0, 5, 50 and 100 mg  L(-1)) of various dose were added to anaerobic bioreactors to examine their anaerobic digestion performance. Results showed that except K and Zn, Ca (~728 to ~1,461 mg  L(-1)), Cr (~0.0022 to ~0.0212 mg  L(-1)), Ni (~0.801 to ~5.362 mg  L(-1)), Co (~0.148 to ~0.580 mg  L(-1)), Mo (~0.044 to ~52.94 mg  L(-1)) and W (~0.658 to ~40.39 mg  L(-1)) had the potential to enhance the biogas production. On the other hand, except Mo and W, inhibitory concentrations IC(50) of Ca, K, Cr, Ni, Zn and Co were found to be ~3252, ~2097, ~0.124, ~7.239, ~0.482, ~8.625 mg  L(-1), respectively. Eight spiked metals showed that they were adsorbed by MSW to a different extent resulting in different liquid metals levels and potential stimulation and inhibition on MSW anaerobic digestion. These results were discussed and compared to results from literature.

Aerobic interval training improves oxygen uptake efficiency by enhancing cerebral and muscular hemodynamics in patients with heart failure

BACKGROUND

Abnormal ventilatory/hemodynamic responses to exercise contribute to functional impairment in patients with heart failure (HF). This study investigates how interval and continuous exercise regimens influence functional capacity by modulating ventilatory efficiency and hemodynamic function in HF patients.

METHODS

Forty-five HF patients were randomized to perform either aerobic interval training (AIT; 3-minute intervals at 40% and 80% VO(2peak)) or moderate continuous training (MCT; sustained 60% VO()for 30 min/day, 3 days/week for 12 weeks, or to a control group that received general healthcare (GHC). A noninvasive bio-reactance device was adopted to measure cardiac hemodynamics, whereas a near-infrared spectroscopy was employed to assess perfusion/O2 extraction in frontal cerebral lobe (∆[THb]FC/∆[HHb]FC) and vastus lateralis (∆[THb]VL/∆[HHb]VL), respectively.

RESULTS

Following the 12-week intervention, the AIT group exhibited higher oxygen uptake efficiency slope (OUES) and lower VE-VCO2 slope than the MCT and GHC groups. Furthermore, AIT, but not MCT, boosted cardiac output (CO) and increased ∆[THb]FC, ∆[THb]VL, and ∆[HHb]VL during exercise. In multivariate analyses, CO was the dominant predictor of VO(2peak). ∆[THb]FC and ∆[THb]VL, which modulated the correlation between CO and OUES, were significantly correlated with OUES. Simultaneously, ∆[THb]VL was the only factor significantly associated with VE-VCO2 slope. Additionally, AIT reduced plasma brain natriuretic peptide, myeloperoxidase, and interleukin-6 levels and increased the Short Form-36 physical/mental component scores and decreased the Minnesota Living with Heart Failure questionnaire score.

CONCLUSIONS

AIT effectively improves oxygen uptake efficiency by enhancing cerebral/muscular hemodynamics and suppresses oxidative stress/inflammation associated with cardiac dysfunction, and also promotes generic/disease-specific qualities of life in patients with HF.

Study of Z Boson Production in PbPb Collisions at √S(NN)=2.76 TeV

A search for Z bosons in the μ(+)μ(-) decay channel has been performed in PbPb collisions at √S(NN)=2.76  TeV with the CMS detector at the LHC, in a 7.2 μb(-1) data sample. The number of opposite-sign muon pairs observed in the 60-120 GeV/c(2) invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of [33.8±5.5(stat)±4.4(syst)]×10(-8), in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.

Measurement of dijet angular distributions and search for quark compositeness in pp collisions at √s = 7 TeV

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at √s = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 pb⁻¹. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Λ⁺ = 5.6 TeV (Λ⁻ = 6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level.

Search for pair production of second-generation scalar leptoquarks in pp collisions at √s = 7 TeV

A search for pair production of second-generation scalar leptoquarks in the final state with two muons and two jets is performed using proton-proton collision data at √s = 7 TeV collected by the CMS detector at the LHC. The data sample used corresponds to an integrated luminosity of 34 pb⁻¹. The number of observed events is in good agreement with the predictions from the standard model processes. An upper limit is set on the second-generation leptoquark cross section times β² as a function of the leptoquark mass, and leptoquarks with masses below 394 GeV are excluded at a 95% confidence level for β = 1, where β is the leptoquark branching fraction into a muon and a quark. These limits are the most stringent to date.