Mechanistic Computational Modeling of Implantable, Bioresorbable Drug Release Systems

Implantable, bioresorbable drug delivery systems offer an alternative to current drug administration techniques; allowing for patient-tailored drug dosage, while also increasing patient compliance. Mechanistic mathematical modeling allows for the acceleration of the design of the release systems, and for prediction of physical anomalies that are not intuitive and may otherwise elude discovery. This study investigates short-term drug release as a function of water-mediated polymer phase inversion into a solid depot within hours to days, as well as long-term hydrolysis-mediated degradation and erosion of the implant over the next few weeks. Finite difference methods are used to model spatial and temporal changes in polymer phase inversion, solidification, and hydrolysis. Modeling reveals the impact of non-uniform drug distribution, production and transport of H+ ions, and localized polymer degradation on the diffusion of water, drug, and hydrolyzed polymer byproducts. Compared to experimental data, the computational model accurately predicts the drug release during the solidification of implants over days and drug release profiles over weeks from microspheres and implants. This work offers new insight into the impact of various parameters on drug release profiles, and is a new tool to accelerate the design process for release systems to meet a patient specific clinical need.

Transcriptomics of acute myeloid leukaemia core bone marrow biopsies reveals distinct therapy response-specific osteo-mesenchymal profiles

While the bone marrow (BM) microenvironment is significantly remodelled in acute myeloid leukaemia (AML), molecular insight into AML-specific alterations in the microenvironment has been historically limited by the analysis of liquid marrow aspirates rather than core biopsies that contain solid-phase BM stroma. We assessed the effect of anthracycline- and cytarabine-based induction chemotherapy on both haematopoietic and non-haematopoietic cells directly in core BM biopsies using RNA-seq and histological analysis. We compared matched human core BM biopsies at diagnosis and 2 weeks after cytarabine- and anthracycline-based induction therapy in responders (<5% blasts present after treatment) and non-responders (≥5% blasts present after treatment). Our data indicated enrichment in vimentin (VIM), platelet-derived growth factor receptor beta (PDGFRB) and Snail family transcriptional repressor 2 (SNAI2) transcripts in responders, consistent with the reactivation of the mesenchymal population in the BM stroma. Enrichment of osteoblast maturation-related transcripts of biglycan (BGN), osteopontin (SPP1) and osteonectin (SPARC) was observed in non-responders. To the best of our knowledge, this is the first report demonstrating distinct osteogenic and mesenchymal transcriptome profiles specific to AML response to induction chemotherapy assessed directly in core BM biopsies. Detailing treatment response-specific alterations in the BM stroma may inform optimised therapeutic strategies for AML.

Basic Salt Additives Modulate the Acidic Microenvironment Around In Situ Forming Implants

There is a growing number of protein drugs, yet their limited oral bioavailability requires that patients receive frequent, high dose injections. In situ forming implants (ISFIs) for controlled release of biotherapeutics have the potential to greatly reduce the injection frequency and improve patient compliance. However, protein release from ISFIs is a challenge due to their proclivity for instability. Specifically, factors such as the acidic microclimate within ISFIs can lead to protein aggregation and denaturation. Basic salts have been shown in PLGA microparticle and microcylinder formulations to significantly reduce protein instability by neutralizing this acidic environment. The overall objective of the study was to demonstrate that basic salts can be used with an ISFI system to neutralize the implant acidification. To this end, the basic salts MgCO3 and Mg(OH)2 were added to a protein-releasing ISFI and the effect on drug release, pH, implant swelling, implant diffusivity, and implant erosion were evaluated. Either salt added at 3 wt% neutralized the acidic environment surrounding the implants, keeping the pH at 6.64 ± 0.03 (MgCO₃) and 6.46 ± 0.11 (Mg(OH)₂) after 28 day compared to 3.72 ± 0.05 with no salts added. The salts initially increased solution uptake into the implants but delayed implant degradation and erosion. The 3 wt% Mg(OH)₂ formulation also showed slightly improved drug release with a lower burst and increased slope. We showed that salt additives can be an effective way to modulate the pH in the ISFI environment, which can improve protein stability and ultimately improve the capacity of ISFIs for delivering pH-sensitive biomolecules. Such a platform represents a low-cost method of improving overall patient compliance and reducing the overall healthcare burden.

Sustained degradation of hyaluronic acid using an in situ forming implant

In pancreatic cancer, excessive hyaluronic acid (HA) in the tumor microenvironment creates a viscous stroma, which reduces systemic drug transport into the tumor and correlates with poor patient prognosis. HA can be degraded through both enzymatic and nonenzymatic methods to improve mass transport properties. Here, we use an in situ forming implant to provide sustained degradation of HA directly at a local, targeted site. We formulated and characterized an implant capable of sustained release of hyaluronidase (HAase) using 15 kDa poly(lactic-co-glycolic) acid and bovine testicular HAase. The implant releases bioactive HAase to degrade the HA through enzymatic hydrolysis at early timepoints. In the first 24 h, 17.9% of the HAase is released, which can reduce the viscosity of a 10 mg/mL HA solution by 94.1% and deplete the HA content within primary human pancreatic tumor samples and ex vivo murine tumors. At later timepoints, as lower quantities of HAase are released (51.4% released in total over 21 d), the degradation of HA is supplemented by the acidic by-products that accumulate as a result of implant degradation. Acidic conditions degrade HA through nonenzymatic methods. This formulation has potential as an intratumoral injection to allow sustained degradation of HA at the pancreatic tumor site.

Quality Improvement Within a Mental Health Setting: Alcohol Detoxification

Aims We describe a clinical audit on alcohol detoxification, using NICE guidelines as a comparable standard. NICE guidelines recommend completing a thorough alcohol history, documentation of a physical examination including screening for Wernicke's encephalopathy, monitoring of vital signs and liver investigations. Breath alcohol level and standardised assessment of withdrawal should be completed in addition to documentation of chlordiazepoxide and thiamine prescriptions. The reported mental health service completed the first cycle of the audit as part of a large-scale, international audit on alcohol detoxification by the Prescribing Observatory for Mental Health, UK (POMH-UK). Two additional audit cycles were completed within the service to ensure continuous quality improvement and clinical effectiveness. Methods Retrospective chart reviews were performed for admissions within pre-defined 6-month periods. Inclusion criteria: ICD-10 F10 diagnosis; prescription of alcohol detoxification schedule. Results This mental health service demonstrated greater compliance with the NICE standards in comparison to other services in the POMH-UK audit. The second-cycle audit showed increased compliance in most areas compared to the initial results. The third-cycle audit focused on two specific areas that required improvement to optimise quality improvement - Breath Alcohol Level and Clinical Institute of Withdrawal Assessment, documentation of which improved from 79% to 85% and 39% to 91% respectively in the final audit cycle. Conclusion The results of this audit indicate that adherence to defined clinical standards within this mental health service exceeds that of the benchmark POMH-UK data. The effectiveness of electronic patient records in improving adherence to set clinical standards, specifically in relation to documentation of clinical parameters is evident. The report also confirms continued improved results with each audit cycle within the service.

External Beam Radiotherapy in Western Africa: 1969-2019

AIMS

We describe the absolute and per capita numbers of megavoltage radiotherapy machines (MVMs) in Western Africa from 1969 to 2019.

MATERIALS AND METHODS

Western Africa was defined in accordance with the United Nations' delineation and inclusive of 16 countries. A literature search for publications detailing the number of cobalt-60 machines (COs) and linear accelerators (LINACs) in radiotherapy centres was carried out. Population data from the World Bank Group and crude cancer rates from the International Agency for Research on Cancer were used to calculate ratios of million persons per MVM and MVMs per 1000 cancer cases.

RESULTS

The numbers of MVMs in Western Africa in 1969, 1979, 1989, 1999 and 2009 were zero, two, three, six and nine, respectively. In 2019 there were 22 MVMs distributed across Ghana (five), Côte d'Ivoire (two), Mali (one), Mauritania (two), Nigeria (nine) and Senegal (three). Nine countries (56.3%) had no history of external beam radiotherapy (EBRT). The largest increase in absolute EBRT capacity occurred from 2017 to 2019, during which 13 MVMs were commissioned. The largest decrease in EBRT capacity occurred from 2015 to 2017, during which four LINACs and three COs were rendered non-operational. The ratio of million persons per MVM improved from 67.0 in 1979 to 17.8 in 2019. As of 2019, there was 0.09 MVM per 1000 cancer cases.

CONCLUSIONS

Western African nations have experienced an increase in the absolute number of MVMs and per capita radiotherapy capacity during the last 50 years, especially in the last decade. As non-functional LINACs contributed to a temporary decline in the EBRT infrastructure, dual use of CO/LINAC technologies may act to promote the availability of EBRT treatment in centres with capacity for multiple MVMs.

The Practice of Paediatric Radiation Oncology in Low- and Middle-income Countries: Outcomes of an International Atomic Energy Agency Study

AIMS

Childhood cancer survival is suboptimal in most low- and middle-income countries (LMICs). Radiotherapy plays a significant role in the standard care of many patients. To assess the current status of paediatric radiotherapy, the International Atomic Energy Agency (IAEA) undertook a global survey and a review of practice in eight leading treatment centres in middle-income countries (MICs) under Coordinated Research Project E3.30.31; 'Paediatric radiation oncology practice in low and middle income countries: a patterns-of-care study by the International Atomic Energy Agency.'

MATERIALS AND METHODS

A survey of paediatric radiotherapy practices was distributed to 189 centres worldwide. Eight leading radiotherapy centres in MICs treating a significant number of children were selected and developed a database of individual patients treated in their centres comprising 46 variables related to radiotherapy technique.

RESULTS

Data were received from 134 radiotherapy centres in 42 countries. The percentage of children treated with curative intent fell sequentially from high-income countries (HICs; 82%) to low-income countries (53%). Increasing deficiencies were identified in diagnostic imaging, radiation staff numbers, radiotherapy technology and supportive care. More than 92.3% of centres in HICs practice multidisciplinary tumour board decision making, whereas only 65.5% of centres in LMICs use this process. Clinical guidelines were used in most centres. Practice in the eight specialist centres in MICs approximated more closely to that in HICs, but only 52% of patients were treated according to national/international protocols whereas institution-based protocols were used in 41%.

CONCLUSIONS

Quality levels in paediatric radiotherapy differ among countries but also between centres within countries. In many LMICs, resources are scarce, coordination with paediatric oncology is poor or non-existent and access to supportive care is limited. Multidisciplinary treatment planning enhances care and development may represent an area where external partners can help. Commitment to the use of protocols is evident, but current international guidelines may lack relevance; the development of resources that reflect the capacity and needs of LMICs is required. In some LMICs, there are already leading centres experienced in paediatric radiotherapy where patient care approximates to that in HICs. These centres have the potential to drive improvements in service, training, mentorship and research in their regions and ultimately to improve the care and outcomes for paediatric cancer patients.

Transglutaminase-2 facilitates extracellular vesicle-mediated establishment of the metastatic niche

The ability of breast cancer cells to interconvert between epithelial and mesenchymal states contributes to their metastatic potential. As opposed to cell autonomous effects, the impact of epithelial–mesenchymal plasticity (EMP) on primary and metastatic tumor microenvironments remains poorly characterized. Herein we utilize global gene expression analyses to characterize a metastatic model of EMP as compared to their non-metastatic counterparts. Using this approach, we demonstrate that upregulation of the extracellular matrix crosslinking enzyme tissue transglutaminase-2 (TG2) is part of a novel gene signature that only emerges in metastatic cells that have undergone induction and reversion of epithelial–mesenchymal transition (EMT). Consistent with our model system, patient survival is diminished when primary tumors demonstrate enhanced levels of TG2 in conjunction with its substrate, fibronectin. Targeted depletion of TG2 inhibits metastasis, while overexpression of TG2 is sufficient to enhance this process. In addition to being present within cells, we demonstrate a robust increase in the amount of TG2 and crosslinked fibronectin present within extracellular vesicle (EV) fractions derived from metastatic breast cancer cells. Confocal microscopy of these EVs suggests that FN undergoes fibrillogenesis on their surface via a TG2 and Tensin1-dependent process. Upon in vivo administration, the ability of tumor-derived EVs to induce metastatic niche formation and enhance subsequent pulmonary tumor growth requires the presence and activity of TG2. Finally, we develop a novel 3D model of the metastatic niche to demonstrate that conditioning of pulmonary fibroblasts via pretreatment with tumor-derived EVs promotes subsequent growth of breast cancer cells in a TG2-dependent fashion. Overall, our studies illustrate a novel mechanism through which EMP contributes to metastatic niche development and distant metastasis via tumor-derived EVs containing aberrant levels of TG2 and fibrillar FN.

3M™ Petrifilm™ Staph Express Count Plate Method for the Enumeration of Staphylococcus aureus in Selected Types of Meat, Seafood, and Poultry: Collaborative Study

The 3M™ Petrifilm™ Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Four foods—cooked, diced chicken; cured ham; smoked salmon; and pepperoni—were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 4 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

Characterizing pediatric inpatient sleep duration and disruptions

OBJECTIVE

To contextualize inpatient sleep duration and disruptions in a general pediatric hospital ward by comparing in-hospital and at-home sleep durations to recommended guidelines and to objectively measure nighttime room entries.

METHODS

Caregivers of patients four weeks - 18 years of age reported patient sleep duration and disruptions in anonymous surveys. Average at-home and in-hospital sleep durations were compared to National Sleep Foundation recommendations. Objective nighttime traffic was evaluated as the average number of room entries between 11:00pm and 7:00am using GOJO brand hand-hygiene room entry data.

RESULTS

Among 246 patients, patients slept less in the hospital than at home with newborn and infant cohorts experiencing 7- and 4-h sleep deficits respectively (Newborn: 787 ± 318 min at home vs. 354 ± 211 min in hospital, p < 0.001; Infants: 703 ± 203 min at home vs. 412 ± 152 min in hospital, p < 0.01). Newborn children also experienced >2 h sleep deficits at home when compared to NSF recommendations (Newborns: 787 ± 318 min at home vs. 930 min recommended, p < 0.05). Objective nighttime traffic measures revealed that hospitalized children experienced 7.3 room entries/night (7.3 ± 0.25 entries). Nighttime traffic was significantly correlated with caregiver-reported nighttime awakenings (Spearman Rank Correlation Coefficient: 0.83, p < 0.001).

CONCLUSION

Hospitalization is a missed opportunity to improve sleep both in the hospital and at home.

Productivity and profitability of forage options for beef production in the subtropics of northern Australia

This study measured forage biomass production, diet quality, cattle liveweight gain, and economic performance of six forage types at 21 sites across 12 commercial beef cattle properties in the Fitzroy River catchment of Queensland during 2011–2014 (28 annual datasets in total). The forages were annual forage crops (oats (Avena sativa), sorghum (Sorghum spp.) and lablab (Lablab purpureus)), sown perennial legume-grass pastures (leucaena-grass (Leucaena leucocephala spp. glabrata + perennial, tropical grass (C4) species) and butterfly pea-grass (Clitoria ternatea + perennial, C4, grass species)), and perennial, C4, grass pastures. The sown forages resulted in 1.2–2.6 times the annual cattle liveweight gain per ha than perennial grass pastures. Annual cattle liveweight gain per ha, forage establishment and management costs, and cattle price margin (sale price less purchase price, $/kg liveweight) all influenced gross margin, however, none was an overriding factor. The average gross margins ($/ha.annum) calculated using contractor rates, ranked from highest to lowest, were: leucaena-grass pastures, 181; butterfly pea-grass pastures, 140; oats, 102; perennial grass, 96; sorghum, 24; and lablab, 18. It was concluded that the tendency towards greater average gross margins for perennial legume-grass pastures than for annual forage crops or perennial grass pastures was the result of the combined effects of lower average forage costs and high cattle productivity.

Subcortical neural synchrony and absolute thresholds predict frequency discrimination independently

The neural mechanisms of pitch coding have been debated for more than a century. The two main mechanisms are coding based on the profiles of neural firing rates across auditory nerve fibers with different characteristic frequencies (place-rate coding), and coding based on the phase-locked temporal pattern of neural firing (temporal coding). Phase locking precision can be partly assessed by recording the frequency-following response (FFR), a scalp-recorded electrophysiological response that reflects synchronous activity in subcortical neurons. Although features of the FFR have been widely used as indices of pitch coding acuity, only a handful of studies have directly investigated the relation between the FFR and behavioral pitch judgments. Furthermore, the contribution of degraded neural synchrony (as indexed by the FFR) to the pitch perception impairments of older listeners and those with hearing loss is not well known. Here, the relation between the FFR and pure-tone frequency discrimination was investigated in listeners with a wide range of ages and absolute thresholds, to assess the respective contributions of subcortical neural synchrony and other age-related and hearing loss-related mechanisms to frequency discrimination performance. FFR measures of neural synchrony and absolute thresholds independently contributed to frequency discrimination performance. Age alone, i.e., once the effect of subcortical neural synchrony measures or absolute thresholds had been partialed out, did not contribute to frequency discrimination. Overall, the results suggest that frequency discrimination of pure tones may depend both on phase locking precision and on separate mechanisms affected in hearing loss.

IDH mutation analysis in gliomas as a diagnostic and prognostic biomarker

INTRODUCTION

There is a high rate of IDH1/2 mutations in low grade gliomas and in high grade gliomas deriving from them. IDH analysis of gliomas is a novel method of classification and an independent prognostic marker. We compared antibody and sequencing methods for the detection of IDH mutations.

METHOD

88 samples from 74 patients were identified. For immunohistochemistry: sections were stained with anti-IDH1R132H antibody. For sequencing: DNA was extracted from fresh, frozen tissue.

RESULTS

28% (20/71) of cases were positive for the R132H IDH1 mutation by antibody. An IDH1 mutation was detected by molecular genetics in 37% (21/57) of cases and no IDH2 mutations were detected. 24% (5/21) had rare IDH1 mutations not detected by immunohistochemistry. Where sufficient tissue was available, immunohistochemistry and DNA analysis were fully concordant for the p.Arg132His mutation. Both Grade II gliomas and anaplastic astrocytomas showed a statistically different distribution of IDH1 mutation load compared to GBMs (p < 0.0001; p = 0.0021 respectively).

CONCLUSION

A rationalised combined approach involving R132H antibody testing and sequencing of negative cases would be ideal for the detection of IDH1 mutations--antibody testing is cheaper than sequencing but sequencing demonstrates rare IDH1 mutations not detected by immunohistochemistry.