Novel SLC30A2 mutations in the pathogenesis of transient neonatal zinc deficiency

Importance

Transient neonatal zinc deficiency (TNZD) occurs in breastfed infants due to abnormally low breast milk zinc levels. Mutations in the solute carrier family 30 member 2 (SLC30A2) gene, which encodes the zinc transporter ZNT2, cause low zinc concentration in breast milk.

Objective

This study aimed to provide further insights into TNZD pathophysiology.

Methods

SLC30A2 sequencing was performed in three unrelated Japanese mothers, whose infants developed TNZD due to low-zinc milk consumption. The effects of the identified mutations were examined using cell-based assays and luciferase reporter analysis.

Results

Novel SLC30A2 mutations were identified in each mother. One harbored a heterozygous missense mutation in the ZNT2 zinc-binding site, which resulted in defective zinc transport. The other two mothers exhibited multiple heterozygous mutations in the SLC30A2 promoter, the first mutations in the SLC30A2 regulatory region reported to date.

Interpretation

This report provides new genetic insights into TNZD pathogenesis in breastfed infants.

Diagnostic Accuracy of Diastolic Fractional Flow Reserve for Functional Evaluation of Coronary Stenosis

Background

In the resting conditions, narrowing the window of coronary pressure measurements from the whole cardiac cycle to diastole improves diagnostic performance of coronary pressure–derived physiological index. However, whether this also applies to the hyperemic conditions has not yet been thoroughly evaluated.

Objectives

The purpose of this study was to assess whether diastolic fractional flow reserve (diastolic FFR) has better diagnostic performance in identifying ischemia-causing coronary lesions than conventional FFR in a prospective, multicenter, and independent core laboratory–based environment.

Methods

In this prospective multicenter registry at 29 Japanese centers, we compared the diagnostic performance of FFR, diastolic FFR, resting distal to aortic coronary pressure (Pd/Pa), and diastolic pressure ratio (dPR) using myocardial perfusion scintigraphy (MPS) as the reference standard in 378 patients with single-vessel coronary disease.

Results

Inducible myocardial ischemia was found on MPS in the relevant myocardial territory of the target vessel in 85 patients (22%). In the receiver-operating curve analyses, diastolic FFR had comparable area under the curve (AUC) compared with FFR (AUC_{diastolic FFR}: 0.66; 95% confidence interval [CI]: 0.58-0.73, vs AUC_FFR: 0.66; 95% CI: 0.58-0.74, P = 0.624). FFR and diastolic FFR showed significantly larger AUCs than resting Pd/Pa (0.62; 95% CI: 0.54-0.70; P = 0.033 and P = 0.046) but did not show significantly larger AUCs than dPR (0.62; 95% CI: 0.55-0.70; P = 0.102 and P = 0.113).

Conclusions

Diastolic FFR showed a similar diagnostic performance to FFR as compared with MPS. This result reaffirms the use of FFR as the most accurate invasive physiological lesion assessment. (Diagnostic accuracy of diastolic fractional flow reserve (d-FFR) for functional evaluation of coronary stenosis; UMIN000015906)

A decrease in tricuspid regurgitation pressure gradient during follow-up in patients with heart failure

Objective

This study aimed to investigate the prognostic impact of the decrease in tricuspid regurgitation pressure gradient (TRPG) at 6-month follow-up in patients after discharge with heart failure (HF).

Background

No previous study has reported the association between TRPG decrease during follow-up and clinical outcomes in HF.

Methods

Among 748 patients with 6-months follow-up echocardiography after discharge from the acute decompensated heart failure in 19 centers in Japan, we analyzed 721 patients with available TRPG data and divided into two groups: the decrease in TRPG group (N=179) and no decrease in TRPG group (N=542). We defined the decrease in TRPG as >10mmHg decrease compared in the initial hospitalization. The primary outcome measure was a composite of all cause deaths and hospitalization due to HF.

Results

The patients in the decrease in TRPG group had a lower prevalence of hypertension, dyslipidemia, atrial fibrillation, and a reduced EF, higher levels of blood albumin and lower levels of sodium than those in no decrease in TRPG group. The median follow-up duration after the follow up echocardiography was 302 (inter quartile range: 206–490), with a 90.9% follow up rate at 6-month. The cumulative 6-month incidence of the primary outcome measure was significantly lower in the decrease in TRPG group than in no decrease in TRPG group (12.2% vs. 18.9%, P=0.0011). After adjusting confounders, the excess risk of the decrease in TRPG relative to no decrease in TRPG for the primary outcome measure remained significant (HR: 0.60, 95% CI 0.34–0.99). There were no significant interactions between the subgroup factors and the effect of the decrease in TRPG for primary outcomes.

Conclusions

HF patients with the decrease in TRPG at 6-month after discharge had a lower risk of clinical outcome than those without decrease in TRPG.

Funding Acknowledgement

Type of funding source: None

Coronary flow reserve can explain some of FFR and iFR discrepancies. Results from international, multicenter and prospective trial

Background

The trial collected prospective data from physiology measurements of borderline lesions in five Czech, one Japan and one Argentinian cathlabs. The main purposes were to analyze diagnostic agreement between FFR (fractional flow reserve) and iFR (instantaneous wave free ratio) examinations and to find possible explanations for discrepant results.

Methods

FFR and iFR examinations were analyzed using Philips-Volcano console and coronary flow reserve (CFR) was analyzed by using Combomap machine Philips-Volcano. Hyperemia for FFR and CFR measurements was induced by intracoronary administration of adenosine. We used CFR as a truth for comparison between FFR and iFR, because CFR has higher impact on patients prognosis than pressures indices.

Results

Data were collected from February 2016 to June 2019 and the database includes 1.789 examinations from 1.492 patients (282 of them, 15.8%, with ACS). CFR were measured in 343 lesions in 293 patients. (ACS 31.2%). Overall correlation between FFR and iFR is high (R=0.86 p<0.0001). The FFR/iFR discrepancy occurred in 84 measurements (24.5%), more frequently it was FFRp (positive) / iFRn (negative) type of discrepancy (65, 18.9%) compare to FFRn/iFRp (19, 5.5%) one. There was no difference in occurrence of FFR/iFR discrepancy in stable patients and ACS ones (25.1%vs. 22.4%, p=0.59). The CFR correlated better with iFR than with FFR (R=0.56, p<0.0001 vs. R= 0.36, p<0.0001) (see table). In lesions with FFRp/iFRn type of discrepancy we found substantially higher CFR value compared to FFR/iFR agreement group (2.4±0.7 vs. 1.5±0.5, p<0.0001). Unlike to FFRn/iFRp discrepancy, where CFR value was similar with agreement group (1.4±0.1 vs. 1.5±0.1, p=0.25)

Conclusion

The FFR/iFR discrepancy occurred in almost one quarter of examinations. Correlation between CFR and iFR is better than between CFR and FFR. High flow is probably one of the main reason for FFRp/iFRn type of discrepancy.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Czech Health Research Council

A case of Cowden syndrome with a novel mutation in the PTEN gene

Cowden syndrome (CS) is an autosomal dominant inherited disorder characterized by macrocephaly and multiple hamartomas. The responsible gene is PTEN (phosphate and tensin homolog detected on chromosome 10), which negatively regulates cell proliferation and survival. We herein present a 46-year-old woman with the typical clinical features of CS. A DNA sequencing analysis of the coding regions and flanking introns of the PTEN gene revealed a novel heterozygous mutation (c.403A > G, p.Ile135Val) in exon 5 that had not been previously reported in CS. J. Med. Invest. 67 : 200-201, February, 2020.

P1252Diagnostic performance of quantitative flow ratio from coronary angiography versus fractional flow reserve from computed tomography

Background

QFR and FFRCT are recently developed, less-invasive techniques for functional assessment of coronary artery disease.

Objectives

We compared the diagnostic performance between fractional flow reserve derived from computed tomography (FFRCT) and quantitative flow ratio (QFR) derived from coronary angiography, using FFR as the standard reference.

Methods

We measured FFRCT, QFR and FFR in 152 patients (233 vessels) with stable coronary artery disease.

Results

QFR was highly correlated with FFR (r=0.78, p<0.001), while FFRCT was moderately correlated with FFR (r=0.63, p<0.001). Both QFR and FFRCT showed good agreements with FFR, presenting small values of mean difference and root-mean-squared deviation (FFR -QFR: 0.02±0.09 and FFR -FFRCT: 0.03±0.11). The AUC of QFR was significantly greater than that of 3D-QCA-derived %DS (0.93 vs. 0.78; difference: 0.15; 95% CI: 0.09 to 0.20; p<0.001). The AUC of FFRCTwas significantly greater than that of CCTA-derived %DS (0.82 vs. 0.70; difference: 0.12; 95% CI: 0.05 to 0.19; p<0.001). The AUC of QFR was significantly greater than that of FFRCT (0.93 vs. 0.82; difference: 0.11; 95% CI: 0.05 to 0.16; p<0.001). The sensitivity, specificity, positive predictive value, and negative predictive valueof QFR ≤0.80 for predicting FFR ≤0.80 were 90%, 82%, 81%, and 90%, respectively. Those of FFRCT ≤0.80 for predicting FFR ≤0.80 were 82%, 70%, 70%, and 82%, respectively. The diagnostic accuracy of QFR ≤0.80 for predicting FFR ≤0.80 was 85% [95% confidence interval: 81% to 89%], while that of FFRCT≤0.80 for predicting FFR ≤0.80was 76% [95% confidence interval: 70% to 80%].

Figure 1. Comparison of FFR ≤0.80 predictors

Conclusions

Both QFR and FFRCTpossessed the ability to accurately evaluate the functional severity of coronary stenosis.

6108Efficacy of the PCSK9 inhibitor for lipid-rich coronary plaque reduction: a near-infrared spectroscopy analysis

Background

Recently, some studies have highlighted proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors produce incremental low-density lipoprotein cholesterol (LDL-C) lowering effect. However, it is unknown whether the lipid composition of plaque changes is associated with serum LDL-C reduction due to PCSK9 inhibitors administration.

Purpose

The purpose of this study was to determine the effects of PCSK9 inhibitor (PCSK9i) on coronary plaque component in patients with a history of coronary artery disease (CAD) assessed by near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS).

Methods

A total of 67 non-culprit coronary segments were identified in 34 patients. These lesions were analyzed utilizing NIRS-IVUS at baseline and follow-up coronary angiography (CAG). The subjects were divided into two groups according to lipid-lowering treatment; administration of PCSK9i group (PCSK9i: 19 segments, 9 patients) and traditional statin treatment group (Control: 48 segments, 25 patients). The change of lipid-rich plaque distribution between baseline and follow-up NIRS-IVUS was defined as the change of maximal lipid core burden index (LCBI) score for each of the 4-mm longitudinal segments (maxLCBI4mm).

Results

Mean duration from baseline to follow-up CAG was 239.4±52.4 days in the PCSK9i group and 341.0±84.1 days in the Control group (p<0.001). Despite the higher total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in the PCSK9i group at baseline (206.6±40.9 mg/dl vs. 168.5±37.1 mg/dl, 131.5±35.4 mg/dl vs. 100.0±29.5 mg/dl; respectively, p<0.001 for both), the PCSK9i group was significantly lower TC and LDL-C at the follow-up (111.5±23.5 mg/dl vs. 157.4±27.8 mg/dl, 40.8±15.7 mg/dl vs. 86.2±19.6 mg/dl; respectively, p<0.001 for both). Furthermore, the PCSK9i group induced greater regression of maxLCBI4mm than that of Control group (99.6±156.6 vs. 27.9±118.0, p=0.046) (Figure).

Figure 1

Conclusion

Compared with traditional statin therapy, PCSK9i treatment resulted in a greater decrease in lipid component in non-culprit coronary plaques. Therefore, PCSK9i may be useful option in preventing from adverse coronary events for the patients with CAD.

P974Efficacy of plaque debulking for bifurcated or ostial lesion by directional coronary atherectomy before 2nd generation drug eluting stent (PERFECT2)

Objectives

We sought to evaluate the efficacy of plaque debulking by directional coronary atherectomy (DCA) before 2nd generation drug-eluting stent (DES) implantation for bifurcated coronary lesions.

Background

Percutaneous coronary intervention (PCI) for bifurcated lesions still remains complex and challenging in terms of restenosis or stent thrombosis regardless of whether simple or complex stenting used.

Methods

Patients with bifurcated lesions were enrolled in this prospective multicenter registry. Pre-2nd generation DES plaque debulking with a novel DCA was conducted. All patients were scheduled to perform a follow up (9–12 months) angiography (coronary angiography or coronary computed tomography). The primary end point was the target vessel failure (TVF) at follow-up. Secondary end points were procedure-related events and major adverse cardiac events at 1 year.

Results

A total of 77 patients with bifurcated lesions were enrolled. PCI with DCA was performed successfully in all without any major procedure-related event and only 1 case needed complex stenting. TVF rate at 9–12 months follow up was 3.9% (3 of 77) and those were all associated with revascularization of the target vessel. Restenosis was only observed at ostial of main-branch in 3cases. No death, no coronary artery bypass grafting, and no myocardial infarction were reported in the patients within the first year.

Figure1

Conclusion

DCA before 2nd generation DES implantation can possibly avoid complex stenting and provide a good mid-term outcome in patients with bifurcated lesions.

Acknowledgement/Funding

None

P2787Gender differences in acute type B aortic dissection

Background

The incidence of aortic dissection has been reported to be lower in women; however, women have a poor prognosis. Also, the incidence of false lumen thrombosis has been reported to be different between Europe, the United States, and Japan. We aimed to determine gender differences in long-term prognosis of acute type B aortic dissection.

Methods

We retrospectively reviewed 220 consecutive patients hospitalized for acute type B aortic dissection between January 2012 to December 2017. After exclusion criteria of unknown onset time, >14 days after the onset, in-hospital death, and aortic events requiring additional treatment during hospitalization were applied, 186 patients were analyzed by gender: 133 men and 53 women. The patient background, treatment method, prognosis, and outcome were compared and examined.

Results

Both the proportions of smoking history and patients receiving oxygen therapy during hospitalization were significantly higher in men (59% vs. 22%, p<0.01; 91% vs. 72%, p<0.01, respectively), whereas that of classical aortic dissection was similar between men and women (41% vs. 32%, p=0.36). The avoidance rate of a composite of all deaths and aortic events 2 years after discharge was similar (hazard ratio, 0.99; 95% confidence interval, 0.52 to 1.59; p=0.966).(Picture1)

Picture 1

Conclusion

The long-term prognosis of acute type B aortic dissection treated by medical therapy during hospitalization was equivalent in men and women despite gender differences in several background factors.

Post-occlusional hyperemia for fractional flow reserve assessment and pull-back curve analysis

Balloon occlusion is a potential method for inducing hyperemia to measure post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR). The objective of this study was to determine the clinical usefulness of post-occlusional hyperemia. FFRs measured using post-occlusional hyperemia caused by 30 (FFR_occl30) and 60 s (FFR_occl60) of balloon occlusion after PCI were compared in 60 lesions from 60 patients. The duration of hyperemia was also measured. There was a strong correlation between FFR_occl30 and FFR_occl60 (r = 0.969, p < 0.01). The duration of hyperemia was significantly longer with FFR_occl60 than with FFR_occl30 (68 ± 23 vs. 37 ± 15 s, p < 0.01). The time required for pullback curve analysis was around 45 s. However, in 7 (12%) cases, the duration of hyperemia with FFR_occl60 was < 45 s, which was not enough for pull-back curve analysis. To predict the duration of hyperemia with FFR_occl60 ≥ 45 s, the receiver operating characteristic curve analysis revealed a cut-off value of 25 s of hyperemia with FFR_occl30. FFR_occl30 is sufficient for diagnostic purposes. FFR_occl60 is suitable for pull-back curve analysis in select cases based on predictions made using the duration of hyperemia with FFR_occl30.

Angiogram based fractional flow reserve in patients with dual/triple vessel coronary artery disease

OBJECTIVE

To assess the performance of angiography derived Fractional Flow Reserve (FFRangio) in multivessel disease (MVD) patients undergoing angiography.

BACKGROUND

FFR is the reference standard for physiologic assessment of coronary stenosis and guidance of revascularization, especially in patients with MVD, yet it remains grossly underutilized. The non-wire based FFRangio performs well in non-MVD patients, but its accuracy in MVD is unknown.

METHODS

A prospective clinical study was conducted at Gifu Heart Centre, Japan. Patients underwent physiologic assessment of all relevant coronary lesions using wire-based FFR (wbFFR) and FFRangio. Primary outcome was diagnostic performance (sensitivity, specificity, accuracy) for FFRangio with wbFFR as reference. Other outcomes were the correlation between wbFFR/FFRangio, time required for wbFFR/FFRangio measurements, and the effect of wbFFR/FFRangio on the reclassification of coronary disease severity.

RESULTS

Fifty patients (118 lesions in total) were included. Mean age was 72 ± 9 years, 72% were male, 36% had triple vessel disease and the average SYNTAX score was 13. The mean measurement of wbFFR and FFRangio were 0.83 ± 0.12 and 0.81 ± 0.11, respectively. Accuracy, sensitivity and specificity for FFRangio were 92.3% (95% CI 79.1-98.4%), 92.4% (95% CI 84.3-97.2%) and 92.4% (95% CI 87.4-97.3%), respectively. Pearson's r between wbFFR and FFRangio was 0.83. FFRangio measurement was faster than wbFFR (9.6 ± 3.4 vs. 15.0 ± 8.9 min, p < 0.001).

CONCLUSIONS

In patients with MVD, FFRangio shows good correlation and excellent diagnostic performance compared to wbFFR, and measuring FFRangio is faster than wbFFR. These results highlight the potential clinical benefits of utilizing FFRangio among patients with MVD.

Cardiac gene therapy in large animals: bridge from bench to bedside

Several clinical trials are evaluating gene transfer as a therapeutic approach to treat cardiac diseases. Although it has just started on the path to clinical application, recent advances in gene delivery technologies with increasing knowledge of underlying mechanisms raise great expectations for the cardiac gene therapy. Although in vivo experiments using small animals provide the therapeutic potential of gene transfer, there exist many fundamental differences between the small animal and the human hearts. Before applying the therapy to clinical patients, large animal studies are a prerequisite to validate the efficacy in an animal model more relevant to the human heart. Several key factors including vector type, injected dose, delivery method and targeted cardiac disease are all important factors that determine the therapeutic efficacy. Selecting the most optimal combination of these factors is essential for successful gene therapy. In addition to the efficacy, safety profiles need to be addressed as well. In this regard, large animal studies are best suited for comprehensive evaluation at the preclinical stages of therapeutic development to ensure safe and effective gene transfer. As the cardiac gene therapy expands its potential, large animal studies will become more important to bridge the bench side knowledge to the clinical arena.

Photocatalytic degradation of p-nitrophenol by zinc oxide particles

The degradation of p-nitrophenol (PNP) by ZnO particles has been studied. With increasing PNP loading the degradation rate decreased. The mineralization of PNP was rather slow compared with the degradation. With a decrease in particle diameter or an increase in surface area, the degradation rate significantly increased. The degradation capability with solar irradiation was found to be superior to UV light irradiation. It was found that 30 mg L(-1) of PNP was completely degraded by solar light with the accumulated UV light of around 23 kJ L(-1) at ZnO dosage of 5 g L(-1). The degradation PNP by ZnO with UV light or solar light was faster than that by TiO(2).

Decolorization and mineralization of Oolong tea polyphenols in colored soft drink wastewater by photo Fenton reaction

The decolorization and the mineralization of the colored soft drink wastewater including Oolong tea polyphenols by the photo Fenton reaction have been investigated. The decolorization of the colored soft drink wastewater including Oolong tea polyphenols by the photo Fenton reaction could be divided into 3 phases. Just after H2O2 was added to the solution, the color of the solution immediately increased from absorbance of 0.247 to 0.711 at the wavelength of 400 nm, which was defined as the 1st phase. Subsequently the significant decolorization by the photo Fenton reaction occurred at the 2nd phase. Finally, complete decolorization (the color attributed to the color of Fe3+) could be achieved in 180 min at the 3rd phase. The instantaneous and considerable color increase at the 1st phase could be attributed to the formation of intermediate colored compounds like quinones and soluble iron complexes produced by the Fenton reaction. About 95% mineralization of model colored soft drink wastewater with 229 mg L(-1) initial TOC concentration was achieved after 165 min.

Oxygen transfer in slurry bioreactors

The oxygen transfer in bioreactors with slurries having a yield stress was investigated. The volumetric mass transfer coefficients in a 40-L bubble column with simulated fermentation broths, the Theological properties of which were represented by the Casson model, were measured. Experimental data were compared with a theoretical correlation developed on the basis of a combination of Higbie's penetration theory and Kolmogoroff's theory of isotropic turbulence. Comparisons between the proposed correlation and data for the simulated broths show good agreement. The mass transfer data for actual mycelial fermentation broths reported previously by the authors were re-examined. Their Theological data was correlated by the Bingham plastic model. The oxygen transfer rate data in the mycelial fermentation broths fit the predictions of the proposed theoretical correlation.

Solubilization of excess sludge in activated sludge process using the solar photo-Fenton reaction

The solubilization of excess sludge by the solar photo-Fenton reaction has been investigated for the reduction of excess sludge in the activated sludge process. The solubilization kinetics depended on the dosages of the Fenton reagents, Fe and H(2)O(2). Increases of initial Fe and H(2)O(2) concentrations in their ranges studied in this work continuously enhanced the sludge solubilization. Cell lysis by the photo-Fenton reaction caused the increase in dissolved chemical oxygen demand (COD) in the first step of sludge solubilization. The further oxidative decomposition of the discharged organic compounds by the photo-Fenton reaction led to the decrease in the dissolved COD as the second step of sludge solubilization. The increase of dissolved COD in the first step of sludge solubilization and the consumption of H(2)O(2) could be described by the pseudo-zero order kinetics based on the accumulated light energy. About 40% reduction of mixed-liquor suspended solids (MLSS) by the solar photo-Fenton reaction was found. It was found that solar light used as a light energy source instead of costly and hazardous artificial UV light was very effective. The dissolved COD for solar photo-Fenton reaction increased faster and by 1.5 times as compared with that by artificial UV light.

Innovative water treatment system coupled with energy production using photo-Fenton reaction

The treatment of colored effluent coupled with energy production using a modified photo-Fenton process has been examined. Fe and carbon plates were employed as an anode and cathode, respectively. In acidic solution, Fe plates would corrode, which leads to elute ferrous ion from Fe plates into the solution and to yield hydrogen gas at the cathode and to generate an electric energy. The eluted ferrous ion could be used for the photo-Fenton reaction. As a result, decolorization of colored effluent and production of electricity and hydrogen could be carried out simultaneously and effectively. It was found that the Orange II concentration in the colored effluent flow decreased up to 84.2% of inlet concentration at 0.8 of relative position in the liquid flow path of continuous photo-reactor. In our proposed system, the energy production, such as an electric power and a hydrogen gas, can be generated at the same time as the decolorization of colored effluent. The produced electric power was 16.5 Wh kg(-1)-Fe(reacted). The produced hydrogen gas was estimated as 13 g-H(2) kg(-1)-Fe(reacted).

Three catheter-based strategies for cardiac delivery of therapeutic gelatin microspheres

Gelatin hydrogel microspheres (GHMs) have been reported as novel non-viral vectors for gene or protein delivery (GHM therapy). However, the components of an effective catheter-based delivery strategy for GHM therapy are unknown. We evaluated the effectiveness of three catheter-based strategies for cardiac GHM therapy: (1) antegrade injection (AI) via coronary arteries; (2) retrograde injection (RI) via coronary veins; and (3) direct myocardial injection (DI) via the coronary sinus. AI distributed microspheres homogeneously throughout the target area with 73+/-11% retention. RI scattered microspheres non-homogenously with 22+/-8% retention. DI distributed microspheres in the needle-advanced area with 47+/-14% retention. However, despite high efficiency, AI did not show biological effects of inducing angiogenesis from basic fibroblast growth factor bound to GHMs. Furthermore, focal micro-infarctions, owing to micro-embolism of aggregated GHMs into small coronary arterioles, were detected in the AI group. Conversely, only RI and DI groups displayed increased coronary flow reserve. DI groups also demonstrated increased capillary density. These results suggest that RI and DI are effective for cardiac GHM therapy, while AI appears inappropriate owing to the risk of focal infarctions.

Aerobic composting of waste activated sludge: kinetic analysis for microbiological reaction and oxygen consumption

In order to examine the optimal design and operating parameters, kinetics for microbiological reaction and oxygen consumption in composting of waste activated sludge were quantitatively examined. A series of experiments was conducted to discuss the optimal operating parameters for aerobic composting of waste activated sludge obtained from Kawagoe City Wastewater Treatment Plant (Saitama, Japan) using 4 and 20 L laboratory scale bioreactors. Aeration rate, compositions of compost mixture and height of compost pile were investigated as main design and operating parameters. The optimal aerobic composting of waste activated sludge was found at the aeration rate of 2.0 L/min/kg (initial composting mixture dry weight). A compost pile up to 0.5 m could be operated effectively. A simple model for composting of waste activated sludge in a composting reactor was developed by assuming that a solid phase of compost mixture is well mixed and the kinetics for microbiological reaction is represented by a Monod-type equation. The model predictions could fit the experimental data for decomposition of waste activated sludge with an average deviation of 2.14%. Oxygen consumption during composting was also examined using a simplified model in which the oxygen consumption was represented by a Monod-type equation and the axial distribution of oxygen concentration in the composting pile was described by a plug-flow model. The predictions could satisfactorily simulate the experiment results for the average maximum oxygen consumption rate during aerobic composting with an average deviation of 7.4%.