Myofibroblasts impair myocardial impulse propagation by heterocellular connexin43 gap-junctional coupling through micropores

Aim: Composite population of myofibroblasts (MFs) within myocardial tissue is known to alter impulse propagation, leading to arrhythmias. However, it remains unclear whether and how MFs alter their propagation patterns when contacting cardiomyocytes (CMs) without complex structural insertions in the myocardium. We attempted to unveil the effects of the one-sided, heterocellular CM-MF connection on the impulse propagation of CM monolayers without the spatial insertion of MFs as an electrical or mechanical obstacle. Methods and results: We evaluated fluo8-based spatiotemporal patterns in impulse propagation of neonatal rat CM monolayers cultured on the microporous membrane having 8-μm diameter pores with co-culture of MFs or CMs on the reverse membrane side (CM-MF model or CM-CM model, respectively). During consecutive pacing at 1 or 2 Hz, the CM monolayers exhibited forward impulse propagation from the pacing site with a slower conduction velocity (θ) and a larger coefficient of directional θ variation in the CM-MF model than that in the CM-CM model in a frequency-dependent manner (2 Hz >1 Hz). The localized placement of an MF cluster on the reverse side resulted in an abrupt segmental depression of the impulse propagation of the upper CM layer, causing a spatiotemporally non-uniform pattern. Dye transfer of the calcein loaded in the upper CM layer to the lower MF layer was attenuated by the gap-junction inhibitor heptanol. Immunocytochemistry identified definitive connexin 43 (Cx43) between the CMs and MFs in the membrane pores. MF-selective Cx43 knockdown in the MF layer improved both the velocity and uniformity of propagation in the CM monolayer. Conclusion: Heterocellular Cx43 gap junction coupling of CMs with MFs alters the spatiotemporal patterns of myocardial impulse propagation, even in the absence of spatially interjacent and mechanosensitive modulations by MFs. Moreover, MFs can promote pro-arrhythmogenic impulse propagation when in face-to-face contact with the myocardium that arises in the healing infarct border zone.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Generation of myocyte agonal Ca2+ waves and contraction bands in perfused rat hearts following irreversible membrane permeabilisation

Although irreversible cardiomyocyte injury provokes intracellular Ca²⁺ ([Ca²⁺]_i) overload, the underlying dynamics of this response and its effects on cellular morphology remain unknown. We therefore visualised rapid-scanning confocal fluo4-[Ca²⁺]_i dynamics and morphology of cardiomyocytes in Langendorff-perfused rat hearts following saponin-membrane permeabilisation. Our data demonstrate that 0.4% saponin-treated myocytes immediately exhibited high-frequency Ca²⁺ waves (131.3 waves/min/cell) with asynchronous, oscillatory contractions having a mean propagation velocity of 117.8 μm/s. These waves slowly decreased in frequency, developed a prolonged decay phase, and disappeared in 10 min resulting in high-static, fluo4-fluorescence intensity. The myocytes showing these waves displayed contraction bands, i.e., band-like actin-fibre aggregates with disruption of sarcomeric α-actinin. The contraction bands were not attenuated by the abolition of Ca²⁺ waves under pretreatment with ryanodine plus thapsigargin, but were partially attenuated by the calpain inhibitor MDL28170, while mechanical arrest of the myocytes by 2,3-butanedione monoxime completely attenuated contraction-band formation. The depletion of adenosine 5'-triphosphate by the mitochondrial electron uncoupler carbonyl cyanide 4-trifluoromethoxy phenylhydrazone also attenuated Ca²⁺ waves and contraction bands. Overall, saponin-induced myocyte [Ca²⁺]_i overload provokes agonal Ca²⁺ waves and contraction bands. Contraction bands are not the direct consequence of the waves but are caused by cross-bridge interactions of the myocytes under calpain-mediated proteolysis.

Abstract P502: Abnormal Myocyte Calcium Dynamics And The Resultant Contraction Band Formation Of The Rat Heart Under Irreversible Injury By Membrane Permeabilization

Ca 2+ overload is a cardinal feature of cardiomyocyte injury, and its progression to irreversible state leads to cell death. However, unknowns are the precise spatiotemporal changes in the myocyte Ca 2+ dynamics and the relevant cell morphology of irreversibly injured hearts. On the hypothesis that myocytes exhibit high-frequency Ca 2+ waves and contraction band necrosis in saponin-permeabilized injured heart, we observed changes in the Ca 2+ dynamics and the relevant morphological changes in the subepicardial myocardium of the Fluo4-loaded rat hearts (n = 14) by rapid-scanning confocal microscopy (100 frames/s) under Langendorff perfusion with 0.3 mM Ca 2+ -Tyrode solution including 0.4 % saponin at 30°C. Also performed was confocal imaging of tetramethylrhodamine methyl ester (TMRM) fluorescence of the myocardium. Under quasi-quiescence of the heart after dissection of the SA node, individual myocytes barely exhibited spontaneous Ca 2+ waves, whereas after commencement of saponin perfusion high-frequency (118 ± 9.7 /min/cell, mean ± SEM) Ca 2+ waves (hereafter, “agonal waves”) emerged within 1 min, showing asynchronous, oscillatory contractions in the individual myocytes with a V prop of 124 ± 2.5 μm/s (n = 60). Subsequently, the waves gradually decreased in frequency with concomitant slowing of its decay time course, and eventually, disappeared in 6 min; myocytes exhibited high, static Fluo4-fluorescence intensity. Along with the progression of Ca 2+ overload by saponin, the TMRM fluorescence intensity was discretely lost in individual myocytes. The myocytes showing the agonal waves exhibited contraction bands, i.e., band-like aggregations of the actin fibers. Under mechanical arrest of the heart by 2,3-butanedione monoxime (20 mM), saponin still induced the agonal waves with a frequency of 253 ± 10.6 /cell/min and V prop of 118 ± 2.1 μm/s (n = 60); however, contraction bands were barely seen.In conclusion, irreversible myocyte injury by saponin provoked agonal Ca 2+ waves and oscillatory contractions indicating progressive Ca 2+ overload and the following mitochondrial damage, which may provide deeper insights into understanding the mechanism of contraction band necrosis.

Kidney injury biomarkers after cardiac angiography in children with congenital heart disease

OBJECTIVE

This study aims to investigate the changes in renal function and levels of urinary biomarkers before and after cardiac angiography in children with congenital heart disease (CHD).

SETTING

Children with CHD are at a risk for kidney injury during contrast exposure in cardiac angiography.

OUTCOME MEASURES

We measured urinary protein, albumin, N-acetyl-β-D-glucosaminidase (NAG), β2-microglobulin (BMG), and liver-type fatty acid-binding protein (L-FABP) levels, as well as serum creatinine and cystatin C levels, before and after cardiac angiography in 33 children with CHD.

RESULTS

No significant decrease was noted in either the creatinine-based or cystatin C-based estimated glomerular filtration rate at 24 hours after angiography compared with that before angiography. Urinary protein, NAG, BMG, and L-FABP levels were significantly increased at 24 hours after angiography, all of which returned to baseline levels at more than 7 days after angiography. An increase in urinary level of protein, albumin, NAG, or BMG was mostly associated with increased urinary L-FABP level. An increase in both urinary BMG and L-FABP, but not that in urinary L-FABP alone, was associated with increased levels of urinary protein and NAG, as well as the greater dose of contrast media.

CONCLUSIONS

Transient increases of kidney injury biomarkers following cardiac angiography are not necessarily associated with the impairment of renal function in a short time period; however, the increase in urinary protein, albumin, NAG, or BMG level may indicate greater stresses to the kidneys than the increase in urinary L-FABP alone in children with CHD.

Controlling joint instability after anterior cruciate ligament transection inhibits transforming growth factor-beta-mediated osteophyte formation

OBJECTIVE

Abnormal joint instability contributes to cartilage damage and osteophyte formation. We investigated whether controlling joint instability inhibited chronic synovial membrane inflammation and delayed osteophyte formation and examined the role of transforming growth factor-beta (TGF-β) signaling in the associated mechanism.

DESIGN

Rats (n = 94) underwent anterior cruciate ligament (ACL) transection. Anterior tibial instability was either controlled (CAM group) or allowed to continue (SHAM group). At 2, 4, and 8 weeks after surgery, radiologic, histopathologic, immunohistochemical, immunofluorescent, and enzyme-linked immunosorbent assay examinations were performed to evaluate osteophyte formation and TGF-β signaling.

RESULTS

Joint instability increased cartilage degeneration score and osteophyte formation, and cell hyperplasia and proliferation and synovial thickening were observed in the synovial membrane. Major findings were increased TGF-β expression and Smad2/3 following TGF-β phosphorylation in synovial membarene, articular cartilage, and the posterior tibial growth plate (TGF-β expression using ELISA: 4 weeks; P = 0.009, 95% CI [260.1-1340.0]) (p-Smad2/3 expression density: 4 weeks; P = 0.024, 95% CI [1.67-18.27], 8 weeks; P = 0.034, 95% CI [1.25-25.34]). However, bone morphogenetic protein (BMP)-2 and Smad1/5/8 levels were not difference between the SHAM model and the CAM model.

CONCLUSIONS

This study showed that the difference between anterior tibial instability caused a change in the expression level of TGF in the posterior tibia and synovial membrane, and the reaction might be consequently involved in osteophyte formation.

Morphological bactericidal fast-acting effects of peracetic acid, a high-level disinfectant, against Staphylococcus aureus and Pseudomonas aeruginosa biofilms in tubing

Background

The bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination. Here, we investigated the bactericidal effect of a high-level disinfectant, peracetic acid (PAA), against Staphylococcus aureus and Pseudomonas aeruginosa biofilm models in vitro.

Methods

S. aureus and P. aeruginosa biofilms were cultured at 35 °C for 7 days with catheter tubes. The following high-level disinfectants (HLDs) were tested: 0.3% PAA, 0.55% ortho-phthalaldehyde (OPA), and 2.0% alkaline-buffered glutaraldehyde (GA). Biofilms were exposed to these agents for 1–60 min and observed after 5 min and 30 min by transmission and scanning electron microscopy. A Student’s t test was performed to compare the exposure time required for bactericidal effectiveness of the disinfectants.

Results

PAA and GA were active within 1 min and 5 min, respectively, against S. aureus and P. aeruginosa biofilms. OPA took longer than 10 min and 30 min to act against S. aureus and P. aeruginosa biofilms, respectively (p < 0.01). Treatment with PAA elicited changes in cell shape after 5 min and structural damage after 30 min.

Conclusions

Amongst the HLDs investigated, PAA elicited the most rapid bactericidal effects against both biofilms. Additionally, treatment with PAA induced morphological alterations in the in vitro biofilm models, suggesting that PAA exerts fast-acting bactericidal effects against biofilms associated with endoscopy-related infections. These findings indicate that the exposure time for bactericidal effectiveness of HLDs for endoscope reprocessing in healthcare settings should be reconsidered.

Frequent somatic mutations in epigenetic regulators in newly diagnosed chronic myeloid leukemia

Although tyrosine kinase inhibitors (TKIs) have significantly improved the prognosis of chronic myeloid leukemia (CML), the ability of TKIs to eradicate CML remains uncertain and patients must continue TKI therapy for indefinite periods. In this study, we performed whole-exome sequencing to identify somatic mutations in 24 patients with newly diagnosed chronic phase CML who were registered in the JALSG CML212 study. We identified 191 somatic mutations other than the BCR-ABL1 fusion gene (median 8, range 1–17). Age, hemoglobin concentration and white blood cell counts were correlated with the number of mutations. Patients with mutations ⩾6 showed higher rate of achieving major molecular response than those<6 (P=0.0381). Mutations in epigenetic regulator, ASXL1, TET2, TET3, KDM1A and MSH6 were found in 25% of patients. TET2 or TET3, AKT1 and RUNX1 were mutated in one patient each. ASXL1 was mutated within exon 12 in three cases. Mutated genes were significantly enriched with cell signaling and cell division pathways. Furthermore, DNA copy number analysis showed that 2 of 24 patients had uniparental disomy of chromosome 1p or 3q, which disappeared major molecular response was achieved. These mutations may play significant roles in CML pathogenesis in addition to the strong driver mutation BCR-ABL1.

Controlling joint instability delays the degeneration of articular cartilage in a rat model

OBJECTIVE

Joint instability induced by anterior cruciate ligament (ACL) transection is commonly considered as a predisposing factor for osteoarthritis (OA) of the knee; however, the influence of re-stabilization on the protection of articular cartilage is unclear. The aim of this study was to evaluate the effect of joint re-stabilization on articular cartilage using an instability and re-stabilization ACL transection model.

DESIGN

To induce different models of joint instability, our laboratory created a controlled abnormal joint movement (CAJM) group and an anterior cruciate ligament transection group (ACL-T). Seventy-five Wistar male rats were randomly assigned to the CAJM (n = 30), ACL-T (n = 30), or no treatment (INTACT) group (n = 15). Cartilage changes were assessed with soft X-ray analysis, histological and immunohistochemistry analysis, and real-time polymerase chain reaction (PCR) analysis at 2, 4, and 12 weeks.

RESULTS

Joint instability, as indicated by the difference in anterior displacement between the CAJM and ACL-T groups (P < 0.001), and cartilage degeneration, as evaluated according to the Osteoarthritis Research Society International (OARSI) score, were significantly higher in the ACL-T group than the CAJM group at 12 weeks (P < 0.001). Moreover, joint re-stabilization maintained cartilage structure (thickness [P < 0.001], surface roughness [P < 0.001], and glycosaminoglycan stainability [P < 0.001]) and suppressed tumor necrosis factor-alpha (TNF-α) and caspase-3 at 4 weeks after surgery.

CONCLUSION

Re-stabilization of joint instability may suppress inflammatory cytokines, thereby delaying the progression of OA. Joint instability is a substantial contributor to cartilage degeneration.

Low-dose thymoglobulin as second-line treatment for steroid-resistant acute GvHD: an analysis of the JSHCT

A nationwide retrospective study for the clinical outcomes of 99 patients who had received thymoglobulin at a median total dose of 2.5 mg/kg (range, 0.5-18.5 mg/kg) as a second-line treatment for steroid-resistant acute GvHD was conducted. Of the 92 evaluable patients, improvement (complete or partial response) was observed in 55 patients (60%). Multivariate analysis demonstrated that male sex and grade III and IV acute GvHD were associated with a lower improvement rate, whereas thymoglobulin dose (<2.0, 2.0-3.9 and ⩾4.0 mg/kg) was NS. Factors associated with significantly higher nonrelapse mortality included higher patient age (⩾50 years), grade IV acute GvHD, no improvement of GvHD and higher dose of thymoglobulin (hazard ratio, 2.55; 95% confidence interval, 1.34-4.85; P=0.004 for 2.0-3.9 mg/kg group and 1.79; 0.91-3.55; P=0.093 for ⩾4.0 mg/kg group). Higher dose of thymoglobulin was associated with a higher incidence of bacterial infections, CMV antigenemia and any additional infection. Taken together, low-dose thymoglobulin at a median total dose of 2.5 mg/kg provides a comparable response rate to standard-dose thymoglobulin reported previously, and <2.0 mg/kg thymoglobulin is recommended in terms of the balance between efficacy and adverse effects.

RNA-binding motif protein 47 inhibits Nrf2 activity to suppress tumor growth in lung adenocarcinoma

RNA-binding proteins provide a new layer of posttranscriptional regulation of RNA during cancer progression. We identified RNA-binding motif protein 47 (RBM47) as a target gene of transforming growth factor (TGF)-β in mammary gland epithelial cells (NMuMG cells) that have undergone the epithelial-to-mesenchymal transition. TGF-β repressed RBM47 expression in NMuMG cells and lung cancer cell lines. Expression of RBM47 correlated with good prognosis in patients with lung, breast and gastric cancer. RBM47 suppressed the expression of cell metabolism-related genes, which were the direct targets of nuclear factor erythroid 2-related factor 2 (Nrf2; also known as NFE2L2). RBM47 bound to KEAP1 and Cullin 3 mRNAs, and knockdown of RBM47 inhibited their protein expression, which led to enhanced binding of Nrf2 to target genomic regions. Knockdown of RBM47 also enhanced the expression of some Nrf2 activators, p21/CDKN1A and MafK induced by TGF-β. Both mitochondrial respiration rates and the side population cells in lung cancer cells increased in the absence of RBM47. Our findings, together with the enhanced tumor formation and metastasis of xenografted mice by knockdown of the RBM47 expression, suggested tumor-suppressive roles for RBM47 through the inhibition of Nrf2 activity.

Comparison of the NMIJ and the ARPANSA standards for absorbed dose to water in high-energy photon beams

The authors report the results of an indirect comparison of the standards of absorbed dose to water in high-energy photon beams from a clinical linac and (60)Co radiation beam performed between the National Metrology Institute of Japan (NMIJ) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Three ionisation chambers were calibrated by the NMIJ in April and June 2013 and by the ARPANSA in May 2013. The average ratios of the calibration coefficients for the three ionisation chambers obtained by the NMIJ to those obtained by the ARPANSA were 0.9994, 1.0040 and 1.0045 for 6-, 10- and 15-MV (18 MV at the ARPANSA) high-energy photon beams, respectively. The relative standard uncertainty of the value was 7.2 × 10(-3). The ratio for (60)Co radiation was 0.9986(66), which is consistent with the results published in the key comparison of BIPM.RI(I)-K4.

TGF-β₁-siRNA delivery with nanoparticles inhibits peritoneal fibrosis

Gene therapies may be promising for the treatment of peritoneal fibrosis (PF) in subjects undergoing peritoneal dialysis (PD). However, a method of delivery of treatment genes to the peritoneum is lacking. We attempted to develop an in vivo small interfering RNA (siRNA) delivery system with liposome-based nanoparticles (NPs) to the peritoneum to inhibit PF. Transforming growth factor (TGF)-β1-siRNAs encapsulated in NPs (TGF-β1-siRNAs-NPs) dissolved in PD fluid were injected into the peritoneum of mice with PF three times a week for 2 weeks. TGF-β1-siRNAs-NPs knocked down TGF-β1 expression significantly in the peritoneum and inhibited peritoneal thickening with fibrous changes. TGF-β1-siRNAs-NPs also inhibited the increase of expression of α-smooth muscle actin-positive myofibroblasts. These results suggest that the TGF-β1-siRNA delivery system with NPs described here could be an effective therapeutic option for PF in subjects undergoing PD.

Accumulation and dissipation of positive charges induced on a PMMA build-up cap of an ionisation chamber by (60)Co gamma-ray irradiation

The signal current from an ionisation chamber with a PMMA build-up cap decreases with irradiation time due to electric fields produced by positive charges induced on the cap. In the present study, it was confirmed that the signal current decreases faster for irradiation using narrower (60)Co gamma-ray beams. This is because the number of secondary electrons that are emitted from surrounding materials and penetrate the build-up cap is smaller in a narrower gamma-ray beam, so that fewer positive charges are neutralised. The ionisation chamber was first subjected to continuous gamma-ray irradiation for 24 h, following which it was irradiated with shorter periodic gamma-ray bursts while measuring the current signal. This allowed the coefficients of positive charge accumulation and dissipation to be determined. It was found that the dissipation coefficient has a large constant value during gamma-ray irradiation and decreases asymptotically to a small value after irradiation is stopped. From the coefficients, the minimum signal current was calculated, which is the value when accumulation and dissipation balance each other under continuous irradiation. The time required for the signal current to recover following irradiation was also calculated.

Colonization of chicken flocks by Campylobacter jejuni in multiple farms in Japan

Campylobacter jejuni was monitored in 4 chicken farms during the period 2003 to 2006 to elucidate the mechanisms of transmission. Three farms (1 to 3), located at least 14 km from each other, belonged to an integrated poultry company, which also provided the farms with day-old chicks from several hatcheries as well as chicken feed. Another farm (4), which belonged to a different company, was located 270 m from farm 1. A total of 206 C. jejuni isolates obtained from the 4 farms were classified into 10 flaA-based RFLP types. Identical RFLP types were found in isolates obtained from chickens originating from multiple hatcheries and reared in different chicken houses on individual farms. Flocks were colonized by strains with 1 or 2 RFLP types in each production cycle, sometimes differing between cycles. Identical RFLP types were found in isolates obtained from the environment around the chicken houses. Using multilocus sequence typing, strains with different RFLP types could be distinguished from each other. Identical RFLP and multilocus sequence typing profiles were found in isolates obtained from farms 1 and 4, and from farms 1 and 2. These results suggest that C. jejuni in these farms comes from common sources external to the farms, even if the farms belong to different companies and obtain chicks from different suppliers.

Effects of estrogen and tamoxifen on the MAP kinase cascade in experimental rat breast cancer

The mitogen-activated protein kinase (MAPK) cascade, which includes MAPK, MAP kinase kinase (MAPKK) and Raf-l, is involved in the signal transduction of growth factor receptors. We found that the MAPK and Raf-l proteins are increased in human breast cancer. Activated MAPKK was also observed. We then investigated whether the MAPK cascade is activated when 7,12-dimethylbenz(a) anthracene (DMBA)-induced rat mammary cancer is treated with 17 beta-estradiol (E-2). Ovariectomy suppressed MAPK expression in tumors, and E-2 administration induced the activation of MAPK in ovariectomized rats. We also investigated the effects of tamoxifen (TAM) on proliferation and the MAPK cascade in DMBA-induced rat mammary cancers. Although tumor size was reduced significantly by TAM, the expression of the MAPK and Raf-l proteins did not decrease. Additionally, MAPK and Raf-l protein expression increased in tumors of ovariectomized rats given TAM, despite a reduction in the size of the tumors. These results suggest that the activated MAPK cascade is important in human breast cancer, and is an important mechanism in the estrogen-dependent growth of DMBA-induced rat mammary cancer. TAM shows E-2-antagonistic effects on tumor proliferation, and E-2-agonistic effects on the MAPK cascade.

Neoadjuvant intra-arterial infusion chemotherapy for invasive thymoma

Four patients with stage III or IVa invasive thymoma successfully underwent surgical intervention and radiotherapy following neoadjuvant intra-arterial chemotherapy including 50 mg/m(2) of cisplatin and 20 mg/m(2) of adriamycin. Remarkable reduction rates (60% or more) of the tumor size were obtained without significant side effects. About 4 weeks after neoadjuvant chemotherapy, an extended thymectomy including invaded organs was easily performed with a small amount of intraoperative bleeding. All patients but one are currently alive and disease-free. This method may be a new therapeutic strategy in the management of invasive thymoma.

A standard for absorbed dose rate to water in a 60Co field using a graphite calorimeter at the National Metrology Institute of Japan

A primary standard for the absorbed dose rate to water in a ⁶⁰Co radiation field has been newly established at the National Metrology Institute of Japan. This primary standard combines the calorimetric measurements using a graphite calorimeter with the ionometric measurements using a thick-walled graphite cavity ionisation chamber. The calorimeter is operated in the constant temperature mode using AC Wheatstone bridges. The absorbed dose rate to water was determined to be 12 mGy s⁻¹ at a point of 1 m from the radiation source and at a water depth of 5 g cm⁻². The uncertainty on the calibration coefficient in terms of the absorbed dose to water of an ionisation chamber using this standard was estimated to be 0.39 % (k=1).

Limited sampling strategies to estimate the area under the concentration-time curve. Biases and a proposed more accurate method

BACKGROUND

Over 100 limited sampling strategies (LSSs) have been proposed to reduce the number of blood samples necessary to estimate the area under the concentration-time curve (AUC). The conditions under which these strategies succeed or fail remain to be clarified.

OBJECTIVES

We investigated the accuracy of existing LSSs both theoretically and numerically by Monte Carlo simulation. We also proposed two new methods for more accurate AUC estimations.

METHODS

We evaluated the following existing methods theoretically: i) nonlinear curve fitting algorithm (NLF), ii) the trapezium rule with exponential curve approximation (TZE), and iii) multiple linear regression (MLR). Taking busulfan (BU) as a test drug, we generated a set of theoretical concentration-time curves based on the identified distribution of pharmacokinetic parameters of BU and re-evaluated the existing LSSs using these virtual validation profiles. Based on the evaluation results, we improved the TZE so that unrealistic parameter values were not used. We also proposed a new estimation method in which the most likely curve was selected from a set of pre-generated theoretical concentration-time curves.

RESULTS

Our evaluation, based on clinical profiles and a virtual validation set, revealed: i) NLF sometimes overestimated the absorption rate constant Ka, ii) TZE overestimated AUC over 280% when Ka is small, and iii) MLR underestimated AUC over 30% when the elimination rate constant Ke is small. These results were consistent with our mathematical evaluations for these methods. In contrast, our two new methods had little bias and good precision.

CONCLUSIONS

Our investigation revealed that existing LSSs induce different but specific biases in the estimation of AUC. Our two new LSSs, a modified TZE and one using model concentration-time curves, provided accurate and precise estimations of AUC.

Detection of titanium dioxide particles on frozen tissue sections using synchrotron radiation X-ray fluorescence analysis

Recent studies into the in vivo absorption and biological influence of particulate matter, especially nanomaterials (NMs), have raised worldwide concerns over their safety. However, it is often technically difficult to conduct these studies because NMs are too small to be observed by optical microscopy. Here, we attempted to establish a new method to visually detect NMs on tissue samples. Specifically, we have analyzed titanium dioxide particles with a diameter of 5 microm, which are widely used in cosmetics, using frozen tissue sections by synchrotron radiation X-ray fluorescence analysis.

Effect of radiation-induced charge accumulation on build-up cap on the signal current from an ionisation chamber

The signal current from a thimble ionisation chamber with a build-up cap made of an insulator decreases by about 0.41 % after being irradiated for 17 h at an air kerma rate of 41 Gy h(-1) by a collimated (60)Co gamma-ray beam in air. In contrast, the signal current remains constant when the thimble ionisation chamber is irradiated in a water phantom. During irradiation, positive charge is considered to accumulate near the outer surface of the build-up cap where electron equilibrium is not achieved. Secondary electrons travelling in the build-up cap and the chamber wall toward the ionisation volume are decelerated by the electric field generated by the positive charge. Consequently, the signal current decreases with increasing charge accumulation because some secondary electrons are prevented from entering the ionisation volume. In the water phantom, electron equilibrium is established in and around the ionisation chamber and charge does not accumulate. To confirm this hypothesis, the signal current was measured for an ionisation chamber in air with a build-up cap wrapped with Al foil and covered with PMMA tubes. Electron equilibrium was established over the build-up cap because the tubes were thicker than the secondary electron range. The signal current decreased with increasing positive voltage applied to the Al foil. It was estimated from the results that positive charges equivalent to a voltage of over 6 kV applied to the Al foil accumulated during irradiation. The signal current was also measured for an ionisation chamber with a metal build-up cap and for an ionisation chamber with a wall and build-up cap made of conductive plastic.

A prospective dose-finding trial using a modified continual reassessment method for optimization of fludarabine plus melphalan conditioning for marrow transplantation from unrelated donors in patients with hematopoietic malignancies

BACKGROUND

Because of the less graft-facilitating effect by bone marrow (BM), we need to assess a dosage of conditioning more accurately particularly in combination with reduced-intensity conditioning. Thus we examined that modified continual reassessment method (mCRM) is applicable for deciding appropriate conditioning of allogeneic BM transplantation.

PATIENTS AND METHODS

The conditioning regimen consisted of i.v. fludarabine (125 mg/m2) plus an examination dose of i.v. melphalan. The primary endpoint was a donor-type T-cell chimerism at day 28 with successful engraftment defined as >90% donor cells. Five patients per dose level were planned to be accrued and chimerism data were used to determine the next dose.

RESULTS

Seventeen patients were enrolled at doses between 130 and 160 mg/m2. The dose was changed from 160 to 130 mg/m(2) (second level) after five full-donor chimerisms. With one patient of 0% chimera in the second level, the dose was increased to 135 mg/m2 (third level). Following five full-donor chimerisms in the third level, the study was complete as projected.

CONCLUSIONS

mCRM was shown to be a relevant method for dose-finding of conditioning regimen. The melphalan dose of 135 mg/m2 was determined as the recommended phase II dose to induce initial full-donor chimerism.

Effect of tube voltage on image quality in 64-section multidetector 3D CT angiography: Evaluation with a vascular phantom with superimposed bone skull structures

BACKGROUND AND PURPOSE

Optimal tube voltage and tube current settings are not well established. The purpose of our study was to investigate the image quality on 3D CT angiograms of the brain at various kilovoltage settings by evaluating the depiction of simulated intracranial lesions by using a vascular phantom.

MATERIALS AND METHODS

An anthropomorphic vascular phantom with superimposed bone skull structures was designed to simulate various intracranial aneurysms with aneurysmal blebs. We performed CT angiography by using a 64-detector row CT scanner for various effective tube currents with 4 tube voltages of 80, 100, 120, and 135 kV(p). Simulated aneurysm enhancement and image noise were quantified; SNR and CNR were calculated. The depiction of the simulated aneurysms and blebs on 3D CT angiograms obtained with the volume-rendering technique was subjectively assessed. The effective dose was calculated on the basis of a CTDIw. The results of several protocols were compared by using the Student t test.

RESULTS

At identical doses levels (CTDIw), the mean SNR and CNR at 100 kV(p) were significantly higher than those at 80, 120, and 135 kV(p); and the mean qualitative image score at 100 kV(p) was significantly superior to those at 80 and 135 kV(p).

CONCLUSIONS

Our phantom study suggests that the tube voltage of 100 kV(p) is desirable for cerebral 3D CT angiograms, and the higher or lower kilovoltage settings may result in the degradation in diagnostic image quality.

Reduction of the radiation dose for multidetector row CT angiography of cerebral aneurysms using an edge-preserving adaptive filter: a vascular phantom study

To determine how much the radiation dose can be reduced in multidetector row CTA using a QDS, we performed CTA at various exposure settings using a vascular phantom simulating various aneurysms with superimposed bone skull structures, and postprocessed the image data with QDS. Our results demonstrated that the radiation dose of CTA can be reduced by at least 25% and the image quality for visualizing aneurysms can be preserved by applying the QDS.