"Primer shot" fractionation with an early treatment break is theoretically superior to consecutive weekday fractionation schemes for early-stage non-small cell lung cancer

PURPOSE

Radiotherapy is traditionally given in equally spaced weekday fractions. We hypothesize that heterogeneous interfraction intervals can increase radiosensitivity via reoxygenation. Through modeling, we investigate whether this minimizes local failures and toxicity for early-stage non-small cell lung cancer (NSCLC).

METHODS

Previously, a tumor dose-response model based on resource competition and cell-cycle-dependent radiosensitivity accurately predicted local failure rates for early-stage NSCLC cohorts. Here, the model mathematically determined non-uniform inter-fraction intervals minimizing local failures at similar normal tissue toxicity risk, i.e., iso-BED3 (iso-NTCP) for fractionation schemes 18Gyx3, 12Gyx4, 10Gyx5, 7.5Gyx8, 5Gyx12, 4Gyx15. Next, we used these optimized schedules to reduce toxicity risk (BED3) while maintaining stable local failures (TCP).

RESULTS

Optimal schedules consistently favored a "primer shot" fraction followed by a 2-week break, allowing tumor reoxygenation. Increasing or decreasing the assumed baseline hypoxia extended or shortened this optimal break by up to one week. Fraction sizes of 7.5 Gy and up required a single primer shot, while smaller fractions needed one or two extra fractions for full reoxygenation. The optimized schedules, versus consecutive weekday fractionation, predicted absolute LF reductions of 4.6%-7.4%, except for the already optimal LF rate seen for 18Gyx3. Primer shot schedules could also reduce BED3 at iso-TCP with the biggest improvements for the shortest schedules (94.6Gy reduction for 18Gyx3).

CONCLUSION

A validated simulation model clearly supports non-standard "primer shot" fractionation, reducing the impact of hypoxia-induced radioresistance. A limitation of this study is that primer-shot fractionation is outside prior clinical experience and therefore will require clinical studies for definitive testing.

Anionic nanoplastic contaminants promote Parkinson's disease-associated α-synuclein aggregation

Recent studies have identified increasing levels of nanoplastic pollution in the environment. Here, we find that anionic nanoplastic contaminants potently precipitate the formation and propagation of α-synuclein protein fibrils through a high-affinity interaction with the amphipathic and non-amyloid component (NAC) domains in α-synuclein. Nanoplastics can internalize in neurons through clathrin-dependent endocytosis, causing a mild lysosomal impairment that slows the degradation of aggregated α-synuclein. In mice, nanoplastics combine with α-synuclein fibrils to exacerbate the spread of α-synuclein pathology across interconnected vulnerable brain regions, including the strong induction of α-synuclein inclusions in dopaminergic neurons in the substantia nigra. These results highlight a potential link for further exploration between nanoplastic pollution and α-synuclein aggregation associated with Parkinson's disease and related dementias.

Anionic Nanoplastic Contaminants Promote Parkinson's Disease-Associated α-Synuclein Aggregation

Recent studies have identified increasing levels of nanoplastic pollution in the environment. Here we find that anionic nanoplastic contaminants potently precipitate the formation and propagation of α-synuclein protein fibrils through a high-affinity interaction with the amphipathic and non-amyloid component (NAC) domains in α-synuclein. Nanoplastics can internalize in neurons through clathrin-dependent endocytosis, causing a mild lysosomal impairment that slows the degradation of aggregated α-synuclein. In mice, nanoplastics combine with α-synuclein fibrils to exacerbate the spread of α-synuclein pathology across interconnected vulnerable brain regions, including the strong induction of α-synuclein inclusions in dopaminergic neurons in the substantia nigra. These results highlight a potential link for further exploration between nanoplastic pollution and α-synuclein aggregation associated with Parkinson's disease and related dementias.

Outcomes of patients with high bleeding risks characteristics presenting with acute coronary syndrome undergoing percutaneous coronary intervention

Background

Patients with high bleeding risk characteristics (HBR) presenting with acute coronary syndrome (ACS) pose a clinical challenge to balance risk for recurrent ischemic events versus incurring bleeding with dual antiplatelet therapy.

Purpose

We seek to determine the incidence and predictors of short and long term ischemic and bleeding outcomes in patients with HBR factors presenting with ACS after percutaneous coronary intervention (PCI).

Method

Consecutive patients over a 1-year period, who underwent PCI for ACS were categorized as having HBR based on: age ≥75, anemia (hemoglobin<110g/L), thrombocytopenia (platelet<100x109/L), renal failure (eGFR<30umol/L) or concurrent use of oral anticoagulation. Primary outcome was major adverse cardiovascular event (MACE) defined as composite of cardiovascular death, myocardial infarction, and stroke at 1 year. Key secondary outcomes include significant bleeding defined as Bleeding Academic Research Consortium (BARC) type 3 or 5, and net adverse cardiovascular event (NACE), as a composite of MACE and significant bleeding.

Results

Of 1351 patients presented with ACS, 389 (28.8%) had at least one HBR criteria. At 1 year, patients with HBR, compared to those without, had increased MACE (11.1% vs 4.2%, p<0.001) and cardiovascular death (5.7% vs 1.7%, p<0.001). Patients with HBR had increased significant bleeding (3.6% vs 2.3%, p=0.011) and NACE (14.4% vs 5.4%, p<0.001). Multivariate analysis showed the presence of HBR and prior history of myocardial infarction were predictors for 1-year MACE (OR 2.67, CI [1.62–4.42], p<0.001 and OR 2.18, CI [1.29–3.70], p=0.004, respectively), whereas the use of second-generation antiplatelet agent was not. Increased MACE and NACE were observed in HBR patients beyond 1 month of DAPT.

Conclusion

Among patients with ACS undergoing PCI, those with HBR had higher risk for both ischemic and bleeding complications. Novel strategies need to be considered for this high-risk group. Current guidelines, recommending 1 year of DAPT for patients with ACS, should be re-evaluated among patients with HBR.

Funding Acknowledgement

Type of funding sources: None. Kaplan-Meier curve for 1 year MACEKaplan-Meier curve for 1 year death

Comparing clinical outcomes following 1 year of dual antiplatelet therapy in patients risk stratified by the PRECISE-DAPT and DAPT scores

Background

Dual antiplatelet therapy (DAPT) is the standard of care following PCI. DAPT reduces ischemic events but increases bleeding risk. Duration of DAPT following PCI remains controversial. Current guidelines recommend duration be individualized based on risk of ischemia and bleeding. Although multiple strategies exist to risk stratify patients, including application of the PRECISE-DAPT and DAPT scores, there is currently no standardized risk assessment protocol.

Purpose

To determine if the PRECISE-DAPT and DAPT scores can identify patients at increased risk of ischemia or bleeding in a cohort prescribed 12 months of DAPT following PCI.

Methods

We calculated the PRECISE-DAPT and DAPT scores for 469 consecutive patients at baseline after PCI. Patients were grouped based on score treatment recommendation; PRECISE-DAPT prolonged or shortened (PRECISE DAPT <25 vs. ≥25) and DAPT prolonged or shortened (DAPT ≥2 vs <2). End points included 1-year rates of major adverse cardiovascular events (MACE) and TIMI major or minor bleeding.

Results

Among 469 patients, mean age was 64.4 (SD 12.2); 102 (21.7%) were women. Index presentation consisted of a STEMI in 207 (44.1%), NSTEMI in 99 (21.1%), and UA in 60 (12.8%). At presentation, 174 (37.1%) were current smokers, 115 (24.5%) had a prior MI, 118 (25.2%) had diabetes, 249 (53.1%) had dyslipidemia and 281 (60.0%) were previously diagnosed as hypertensive. Overall, there was an increase in bleeding and no difference in MACE for patients with a PRECISE-DAPT score ≥25 (13.3% vs. 4.1% P<0.001). No difference in bleeding or MACE was present in patients stratified by the DAPT score.

Conclusion

A PRECISE-DAPT score ≥25 was associated with an increased rate of bleeding and no difference in MACE in patients prescribed 12 months of DAPT. This supports the use of the PRECISE-DAPT as a prospective tool in clinical practice.

Funding Acknowledgement

Type of funding source: None

P1933Comparing treatment recommendations for the DAPT and PRECISE-DAPT scores after percutaneous coronary intervention

Background

Dual antiplatelet therapy (DAPT), with aspirin and a P2Y12 inhibitor, is the standard therapy for patients following PCI. Duration of treatment with DAPT has been controversial despite large studies. Current guidelines recommend treatment duration be individualized based on risk of ischemia and bleeding. To facilitate treatment decisions, risk assessment tools, including the DAPT and PRECISE-DAPT scores, have been developed.

Purpose

As components of these scores differ, the variability of recommendation remains unknown. We set to evaluate inter-tool concordance in treatment recommendation in a cohort of patients after PCI.

Methods

Using data from our local PCI registry, we calculated the PRECISE-DAPT at baseline following PCI and the DAPT after 1 year of treatment for 311 consecutive patients with complete data for both scores to be calculated. Based on their DAPT and PRECISE-DAPT scores, patients were grouped into concordant for long-term treatment (DAPT ≥2 and PRECISE-DAPT <25) or concordant for shortened treatment (DAPT <2 and PRECISE- DAPT ≥25). All other patients were considered discordant. We then performed a concordance analysis using Cohen's kappa to measure degree of agreement.

Results

Among the 311 patients, mean age was 63.4 (SD 11.6); 245 (79%) were men, 93 (29.9%) had history of a prior MI, 130 (41.8%) were current smokers, 32 (10.3%) had a history of CHF or LVEF <30%, 82 (26.3%) had diabetes and 196 (63.0%) were previously diagnosed with hypertension. Index event consisted of a STEMI in 101 (32.4%), NSTEMI in 93 (29.9%), unstable angina in 27 (8.7%), stable angina in 67 (21.5%) and the remaining 23 (7.4%) had other indications for PCI. Mean DAPT score was 1.52 (SD 1.37). Mean PRECISE-DAPT was 17.65 (SD 12.73). The DAPT recommended long-term treatment for 162 (52.1%) and shortened treatment for 149 (47.9%). The PRECISE-DAPT recommended long-term treatment for 245 (78.9%) and shortened treatment for 66 (21.2%). The overall proportion of agreement between the two risk scores was 56.6% with a Cohen's kappa index of 0.110 (95% CI, 0.017 to 0.204). See Table.

Concordance Analysis PRECISE-DAPT Score Recommendation Long Term (N=245) Shortened (N=66) DAPT Score Recommendation Long Term (N=162) 136 (43.7%) 26 (8.4%) Concordant for Long Term Treatment Shortened (N=149) 109 (35%) 40 (12.8%) Concordant for Shortened Treatment

Conclusion

Comparison of the DAPT score and the PRECISE-DAPT score showed concordance in treatment recommendation in only 56.6% of patients. Given the poor agreement between these tools, prospective concurrent evaluations and correlation to outcomes will be required in future studies.

The Plastid Terminal Oxidase is a Key Factor Balancing the Redox State of Thylakoid Membrane

Mitochondria possess oxygen-consuming respiratory electron transfer chains (RETCs), and the oxygen-evolving photosynthetic electron transfer chain (PETC) resides in chloroplasts. Evolutionarily mitochondria and chloroplasts are derived from ancient α-proteobacteria and cyanobacteria, respectively. However, cyanobacteria harbor both RETC and PETC on their thylakoid membranes. It is proposed that chloroplasts could possess a RETC on the thylakoid membrane, in addition to PETC. Identification of a plastid terminal oxidase (PTOX) in the chloroplast from the Arabidopsis variegation mutant immutans (im) demonstrated the presence of a RETC in chloroplasts, and the PTOX is the committed oxidase. PTOX is distantly related to the mitochondrial alternative oxidase (AOX), which is responsible for the CN-insensitive alternative RETC. Similar to AOX, an ubiquinol (UQH2) oxidase, PTOX is a plastoquinol (PQH2) oxidase on the chloroplast thylakoid membrane. Lack of PTOX, Arabidopsis im showed a light-dependent variegation phenotype; and mutant plants will not survive the mediocre light intensity during its early development stage. PTOX is very important for carotenoid biosynthesis, since the phytoene desaturation, a key step in the carotenoid biosynthesis, is blocked in the white sectors of Arabidopsis im mutant. PTOX is found to be a stress-related protein in numerous research instances. It is generally believed that PTOX can protect plants from various environmental stresses, especially high light stress. PTOX also plays significant roles in chloroplast development and plant morphogenesis. Global physiological roles played by PTOX could be a direct or indirect consequence of its PQH2 oxidase activity to maintain the PQ pool redox state on the thylakoid membrane. The PTOX-dependent chloroplast RETC (so-called chlororespiration) does not contribute significantly when chloroplast PETC is normally developed and functions well. However, PTOX-mediated RETC could be the major force to regulate the PQ pool redox balance in the darkness, under conditions of stress, in nonphotosynthetic plastids, especially in the early development from proplastids to chloroplasts.

Basiliximab with delayed introduction of calcineurin inhibitors as a renal-sparing protocol following liver transplantation in children with renal impairment

Renal impairment is frequently compromised in patients with end-stage liver disease and is associated with increased long-term mortality post-LT. In contrast to CNI, basiliximab is an immunosuppressive agent with minimal nephrotoxic potential. This study reviews the experience of a single pediatric liver transplant center's renal-sparing approach with the use of basiliximab and MMF to compensate for delayed entry of CNI in children with renal impairment at the time of organ availability. There were no differences in renal function between pediatric patients with and without pre-LT renal impairment within the first year (cGFR: 135 mL/min/1.73 m2 vs. 144 mL/min/1.73 m2 ; p = 0.56) or at 5-8 yr following LT, (129 mL/min/1.73 m2 vs. 130 mL/min/1.73 m2 ; p = 0.97). In addition, there was no difference in ACR rates (50% vs. 43%, p = 0.62) between patients in the basiliximab group and those patients receiving standard CNI and steroid strategies. The utilization of a renal-sparing approach with basiliximab alongside delayed entry and lower early target trough levels of CNI in children with renal impairment at the time of LT is safe and maintains excellent long-term kidney function.

An environmental epigenetic study of ADRB2 5'-UTR methylation and childhood asthma severity

BACKGROUND

Beta-2 adrenergic receptor (ADRB2) is the primary target of both short- and long-acting beta-agonist asthma medications. ADRB2 5'-UTR methylation changes in blood have the potential to act as a surrogate biomarker of responsiveness to beta-agonist treatment and childhood asthma severity.

OBJECTIVE

To study the association between ADRB2 5'-UTR methylation, NO (2) exposure and childhood asthma severity.

METHODS

We compared ADRB2 5'-UTR methylation levels in blood between 60 children with mild asthma and 122 children with severe asthma using methylation-specific PCR. We also investigated potential joint effects between NO (2) exposure and ADRB2 5'-UTR methylation.

RESULTS

We found a significant association between intermediate (OR: 4.11, 95% CI: 1.58-10.73) and high levels (OR: 7.63, 95% CI: 3.02-19.26) of ADRB2 methylation and severe childhood asthma. In addition, we found a significant association between indoor exposure to NO (2) , an air pollutant and known asthmogen, and severe asthma among children exhibiting high ADRB2 methylation (OR: 4.59, 95% CI: 1.03-20.55) but no association among children exhibiting low levels of ADRB2 methylation (OR: 0.35, 95% CI: 0.01-14.13).

CONCLUSIONS AND CLINICAL RELEVANCE

These findings support the potential use of ADRB2 5'-UTR methylation as a biomarker of both asthma severity and risk for NO (2) -associated asthma exacerbations in children, and present the first evidence of an epigenetic link between an important environmental exposure and childhood asthma severity.

Electro-acupuncture-mediated gene transfer

Gene transfer is one of the key techniques in gene therapy application. Unfortunately, it seems that by now, there still exists no approach with simplicity, easiness, efficiency and safety. A novel method for gene delivery, electro-acupuncture needle-mediated gene transfer which combined the Chinese traditional acupuncture with modem gene introduction, was developed. With acupuncture needle carrying exogenous gene into muscle after direct electronic stimuli, efficient gene delivery was achieved.

Polymorphisms and haplotypes in the bovine neuropeptide Y, growth hormone receptor, ghrelin, insulin-like growth factor 2, and uncoupling proteins 2 and 3 genes and their associations with measures of growth, performance, feed efficiency, and carcass merit in beef cattle1

Genes that regulate metabolism and energy partitioning have the potential to influence economically important traits in farm animals, as do polymorphisms within these genes. In the current study, SNP in the bovine neuropeptide Y (NPY), growth hormone receptor (GHR), ghrelin (GHRL), uncoupling proteins 2 and 3 (UCP2 and UCP3), IGF2, corticotrophin-releasing hormone (CRH), cocaine and amphetamine regulated transcript (CART), melanocortin-4 receptor (MC4R), proopiomelanocortin (POMC), and GH genes were evaluated for associations with growth, feed efficiency, and carcass merit in beef steers. In total, 24 SNP were evaluated for associations with these traits and haplotypes were constructed within each gene when 2 or more SNP showed significant associations. An A/G SNP located in intron 4 of the GHR gene had the largest effects on BW of the animals (dominance effect P < 0.01) and feed efficiency (allele substitution effect P < 0.05). Another A/G SNP located in the promoter region of GHR had similar effects but the haplotypes of these 2 SNP reduced the effects of the SNP located in intron 4. Three SNP in the NPY gene showed associations to marbling (P < 0.001) as well as with ADG, BW, and feed conversion ratio (FCR; P < 0.05). The combination of these 3 SNP into haplotypes generally improved the association or had a similar scale of association as each single SNP. Only 1 SNP in UCP3, an A/G SNP in intron 3, was associated with ADG (P = 0.025), partial efficiency of growth, and FCR (P < 0.01). Three SNP in UCP2 gene were in almost complete linkage disequilibrium and showed associations with lean meat yield, yield grade, DMI, and BW (P < 0.05). Haplo-types between the SNP in UCP3 and UCP2 generally reduced the associations seen individually in each SNP. An A/G SNP in the GHRL gene tended to show effects on residual feed intake, FCR, and partial efficiency of growth (P < 0.10). The IGF2 SNP most strongly affected LM area (P < 0.01), back fat, ADG, and FCR (P < 0.05). The SNP in the CART, MC4R, POMC, GH, and CRH genes did not show associations at P < 0.05 with any of the traits. Although most of the SNP that showed associations do not cause amino acid changes, these SNP could be linked to other yet to be detected causative mutations or nearby QTL. It will be very important to verify these results in other cattle populations.

Global gene expression patterns spanning 3T3-L1 preadipocyte differentiation

Adipogenesis is of significant relevance from an agricultural perspective. Traits such as subcutaneous fat thickness, marbling and waste fat are of substantial economic importance in animal production. In order to discover more about the genetic basis of this process, a study was undertaken to examine the changes that occur daily in global gene expression as 3T3-L1 cells differentiate from preadipocyte to adipocyte. Duplicate RNA samples were collected daily during the differentiation process and probed with the Affymetrix U74Av2 GeneChip® microarray to allow the time-course analysis of the gene expression profile in these differentiating cells. Self-organizing maps (SOM) clustering was performed to extract patterns of expression over the course of the experiment (day 0 to day 6). The clustering generated nine distinct expression patterns containing between 74 and 420 genes/ESTs. Functional clusters and important chronological changes in the expression of key genes and gene groups were identified. The pattern of expression observed for many genes not only confirmed what has been shown previously for the early stages of differentiation, but also expanded this pattern to cover the whole differentiation process thus giving a very comprehensive overview of patterns and changes in gene expression over the time course of adipocyte differentiation. Key words: Adipocyte differentiation, gene expression, SOM clustering

A comparative map of bovine chromosome 19 based on a combination of mapping on a bacterial artificial chromosome scaffold map, a whole genome radiation hybrid panel and the human draft sequence

We have constructed a medium density physical map of bovine chromosome 19 using a combination of mapping loci on both a bovine bacterial artificial chromosome (BAC) scaffold map and a whole genome radiation hybrid (WGRH) panel. The resulting map contains 70 loci spanning the length of bovine chromosome 19. Three contiguous groups of BACs were identified on the basis of multiple loci mapping to individual BAC clones. Bovine chromosome 19 was found in this study to be comprised almost entirely from regions of human chromosome 17, with a small region putatively assigned to human chromosome 10. Fourteen breakpoints between the bovine and human chromosomes were detected, with a possibility of five more based on ordering of the WGRH map.