MR compatible positioning device for guiding a focused ultrasound system for the treatment of brain deseases

BACKGROUND

A prototype magnetic resonance imaging (MRI)-compatible positioning device that navigates a high intensity focused ultrasound (HIFU) transducer is presented. The positioning device has three user-controlled degrees of freedom that allow access to brain targets using a lateral coupling approach. The positioning device can be used for the treatment of brain cancer (thermal mode ultrasound) or ischemic stroke (mechanical mode ultrasound).

MATERIALS AND METHODS

The positioning device incorporates only MRI compatible materials such as piezoelectric motors, ABS plastic, brass screws, and brass rack and pinion.

RESULT

The robot has the ability to accurately move the transducer thus creating overlapping lesions in rabbit brain in vivo. The registration and repeatability of the system was evaluated using tissues in vitro and gel phantom and was also tested in vivo in the brain of a rabbit.

CONCLUSION

A simple, cost effective, portable positioning device has been developed which can be used in virtually any clinical MRI scanner since it can be placed on the table of the MRI scanner. This system can be used to treat in the future patients with brain cancer and ischemic stroke.

Cardioprotection by selective SGLT-2 inhibitors in a non-diabetic mouse model of myocardial ischemia/reperfusion injury: a class or a drug effect?

Major clinical trials with sodium glucose co-transporter-2 inhibitors (SGLT-2i) exhibit protective effects against heart failure events, whereas inconsistencies regarding the cardiovascular death outcomes are observed. Therefore, we aimed to compare the selective SGLT-2i empagliflozin (EMPA), dapagliflozin (DAPA) and ertugliflozin (ERTU) in terms of infarct size (IS) reduction and to reveal the cardioprotective mechanism in healthy non-diabetic mice. C57BL/6 mice randomly received vehicle, EMPA (10 mg/kg/day) and DAPA or ERTU orally at the stoichiometrically equivalent dose (SED) for 7 days. 24 h-glucose urinary excretion was determined to verify SGLT-2 inhibition. IS of the region at risk was measured after 30 min ischemia (I), and 120 min reperfusion (R). In a second series, the ischemic myocardium was collected (10th min of R) for shotgun proteomics and evaluation of the cardioprotective signaling. In a third series, we evaluated the oxidative phosphorylation capacity (OXPHOS) and the mitochondrial fatty acid oxidation capacity by measuring the respiratory rates. Finally, Stattic, the STAT-3 inhibitor and wortmannin were administered in both EMPA and DAPA groups to establish causal relationships in the mechanism of protection. EMPA, DAPA and ERTU at the SED led to similar SGLT-2 inhibition as inferred by the significant increase in glucose excretion. EMPA and DAPA but not ERTU reduced IS. EMPA preserved mitochondrial functionality in complex I&II linked oxidative phosphorylation. EMPA and DAPA treatment led to NF-kB, RISK, STAT-3 activation and the downstream apoptosis reduction coinciding with IS reduction. Stattic and wortmannin attenuated the cardioprotection afforded by EMPA and DAPA. Among several upstream mediators, fibroblast growth factor-2 (FGF-2) and caveolin-3 were increased by EMPA and DAPA treatment. ERTU reduced IS only when given at the double dose of the SED (20 mg/kg/day). Short-term EMPA and DAPA, but not ERTU administration at the SED reduce IS in healthy non-diabetic mice. Cardioprotection is not correlated to SGLT-2 inhibition, is STAT-3 and PI3K dependent and associated with increased FGF-2 and Cav-3 expression.

Pteridine and riboflavin patterns during tail regeneration in Triturus species and the effects of chloramphenicol, isoxanthopterin and reserpine

In Triturus cristatus amputation causes the reappearance of larval tetrahydrobiopterin, thus raising the ratios tetrahydrobiopterin/isoxanthopterin and tetrahydrobiopterin/riboflavin from zero to values between 3-5. This increase first occurs in the remaining skin and in the eyes. The increase of both ratios in the regeneration bud, beginning with the 20th day after amputation, coincides with their drop in both other tissues. Chloramphenicol and isoxanthopterin both strongly inhibit the formation of a regeneration bud. They also block the increase of both ratios in the remaining skin and in the rudimental regenerate as well. Reserpine induces regenerative ability in Triturus vulgaris, which normally lacks this. It has a strong melanizing effect and, moreover, it causes an increase of both ratios in the regeneration bud and in the remaining skin.

Pteridine and riboflavin in tumor tissue and the effect of chloramphenicol and isoxanthopterin

Human squamous cell carcinoma has elevated levels of tetrahydrobiopterin. As the level of riboflavin is low, the ratio tetrahydrobiopterin/riboflavin shows values of 5 - 8.3. In contrast, in differentiated tissues with high metabolic activity but low mitotic rate, like submaxillary glands, elevated levels of tetrahydrobiopterin are accompanied by high content of riboflavin. Thus the ratio tetrahydrobiopterin/riboflavin in kept as low as about 0.5. Chloramphenicol and, in particular, isoxanthopterin reduce tumor growth in rats and prevent tetrahydrobiopterin accumulation as well.

WeakMeSH: Leveraging provenance information for weakly supervised classification of biomedical articles with emerging MeSH descriptors

Medical Subject Headings (MeSH) is a hierarchically structured thesaurus created by the National Library of Medicine of USA. Each year the vocabulary gets revised, bringing forth different types of changes. Those of particular interest are the ones that introduce new descriptors in the vocabulary either brand new or those who come up as a product of a complex change. These new descriptors often lack ground truth articles and rendering learning models that require supervision not applicable. Furthermore, this problem is characterized by its multi label nature and the fine-grained character of the descriptors that play the role of classes, requiring expert supervision and a lot of human resources. In this work, we alleviate these issues through retrieving insights from provenance information about those descriptors present in MeSH to create a weakly labeled train set for them. At the same time, we make use of a similarity mechanism to further filter the weak labels obtained through the descriptor information mentioned earlier. Our method, called WeakMeSH, was applied on a large-scale subset of the BioASQ 2018 data set consisting of 900 thousand biomedical articles. The performance of our method was evaluated on BioASQ 2020 against several other approaches that had given competitive results in similar problems in the past, or apply alternative transformations against the proposed one, as well as some variants that showcase the importance of each different component of our proposed approach. Finally, an analysis was performed on the different MeSH descriptors each year to assess the applicability of our method on the thesaurus.

Cardiac ischemia/reperfusion increases cardiomyocyte KLF5 in pigs and mice that aggravates tissue injury and remodeling

AIMS

Activation of the transcriptional factor Krüppel-like factor 5 (KLF5) is detrimental to chronic heart failure. We explored the involvement of KLF5 in myocardial ischemia/reperfusion injury.

METHODS AND RESULTS

Yorkshire pigs underwent 75΄ of ischemia, followed by 3h or 24h of reperfusion. C57BL/6J mice underwent 30΄ of ischemia, followed by 10', 2h, 12h, 24h, or 4 weeks of reperfusion. Hearts and isolated cardiomyocytes were analyzed for gene expression. We assessed cardiac function, infarct size (IS), oxidative stress, and fibrosis in mice subjected to pharmacologic or genetic KLF5 inhibition, as well as pharmacologic inhibition of NADPH oxidases or Glucose Transporter (GLUT)1 and GLUT4. Bulk RNA sequencing, untargeted 1H-NMR metabolomics and LC-MS lipidomics were performed. Isolated primary murine cardiomyocytes were infected with recombinant adenovirus expressing KLF5. During reperfusion, cardiοmyocyte KLF5 expression was increased in porcine and murine hearts. Pharmacologic or cardiomyocyte-specific genetic inhibition of KLF5 reduced IS and improved cardiac function in mice. Importantly, acute KLF5 inhibition during early reperfusion suppressed fibrosis and preserved systolic cardiac function 4 weeks post-ischemia/reperfusion. This improvement was associated with lower NOX4 expression, less oxidative stress, and suppressed inflammation and cell apoptosis. Pharmacologic inhibition of NOX4 conferred the same benefit. Metabolomic analysis indicated that KLF5 inhibition lowered glucose-derived metabolites (UDP-Glucose and Lactate) at early reperfusion. Accordingly, cardiac GLUT1 and GLUT4 levels were increased with ischemia/reperfusion, which was reverted by KLF5 inhibition. Pharmacologic inhibition of both GLUT1/4 reduced IS. Finally, myocardial KLF5 overexpression increased GLUT1 mRNA levels and mouse mortality.

CONCLUSIONS

Ischemia/reperfusion increases cardiomyocyte KLF5 expression in pigs and mice. This constitutes a central element of myocardial injury pathophysiology and is associated with stimulation of GLUT1 and GLUT4 expression, activation of NOX4, oxidative stress, inflammation and apoptosis. Acute KLF5 inhibition during reperfusion constitutes a novel therapeutic approach against myocardial ischemia/reperfusion injury.

Empagliflozin rescues primary murine cardiac fibroblasts, but not cardiomyocytes, from hypoxia-reoxygenation injury through STAT3-mediated cascades

Introduction

Empagliflozin (EMPA) is a selective sodium glucose co-transporter 2 inhibitor (SGLT2i) and an established drug against type 2 diabetes mellitus. Cardiovascular clinical outcome trials on EMPA have shown a reduced mortality rate related to major cardiovascular events, but the precise mechanism of action remains elusive. We have previously proved that chronic EMPA administration reduces infarct size in an in vivo murine model of ischemia / reperfusion injury, irrespective of the diabetic status. The cardioprotective effect of EMPA was attributed to the increase of Signal Transducer and Activator of Transcription 3 (STAT3) phosphorylation.

Purpose

In this study we aimed to decipher the cell specific effects of EMPA on primary adult ventricular murine cardiomyocytes (pAVMCs) and primary murine cardiac fibroblasts (pMCFs), subjected to hypoxia/reoxygenation (HYP/REO) and to 1) investigate the effect of EMPA on cell death, and 2) reveal the mechanism of cardioprotection.

Methods

PAVMCs and pMCFs were isolated from adult C57BL/6 murine hearts (n=4–6) and were incubated with EMPA (500nM–100nM) for 24 hours. Cells were then subjected to 3 hours of HYP (99% N2), followed by 1 hour of REO. STATTIC, a selective STAT3 inhibitor was used (500nM–1μM) to determine the contribution of STAT3 on the observed effect. MTT assay was performed at the end of REO to determine cell viability. To unravel the mechanism of cardioprotection, the experimental protocol was repeated, and the cells were either stained with dihydroethidium (DHE) dye to determine relative oxidative stress changes or were harvested for isolation of total protein content. We focused on STAT3 and Akt kinase as key mediators of the cardioprotective survivor activating factor enhancement (SAFE) and the reperfusion injury salvage kinase (RISK) pathways. We also investigated the expression of Cardiotrophin-1 (CT-1), as a potential upstream mediator of STAT3 phosphorylation.

Results

The evaluation of cell death revealed that pMCFs viability was significantly increased upon EMPA treatment. Added to this, STATTIC co-treatment with EMPA blunted the protective effect on pMCFs, which indicates that EMPA's protection is STAT3-mediated. Oxidative stress remained unaltered by the treatments. Investigation of the molecular pathways that are responsible for the increased viability of pMCFs revealed that EMPA treatment induces an increased phosphorylation of STAT3 and an increase in CT-1 expression, which are both reversed by STATTIC. Akt phosphorylation and expression remained unchanged by EMPA treatment. Notably, the effect of EMPA on pAVMCs' viability was negligible.

Conclusion(s)

EMPA does not protect pAVMCs, from HYP/REO injury. EMPA rescues the pMCFs in a STAT-3 dependent manner which indicates that EMPA's cardioprotective effect is cell specific and implicates the SAFE pathway.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Boehringer Ingelheim International GmbHGrant title: “Investigation of the distinct effects of Empagliflozin on different cell populations of the healthy myocardium”

Comparative study on the cardioprotective effects against ischemia/reperfusion injury of the selective SGLT2 inhibitors, empagliflozin, dapagliflozin and ertugliflozin in non-diabetic mice

Background/Introduction

The sodium glucose co-transporter 2 selective inhibitors (SGLT2i) empagliflozin (EMPA), dapagliflozin (DAPA) and ertugliflozin (ERTU) are established drugs against type 2 diabetes mellitus (T2DM). However, the clinical outcomes among them differ; EMPA and DAPA treatment significantly reduced the frequency of cardiovascular events, while ERTU did not reach this endpoint. Thus, the comparative cardioprotective properties and further mechanistic insights for each SGLT2i should be elucidated.

Purpose

We have previously proved that chronic EMPA administration reduces infarct size (IS), independently of the presence of T2DM in vivo. We aimed to 1) investigate the comparative cardioprotective effect of EMPA, DAPA and ERTU in terms of IS reduction upon short term administration and 2) reveal the mechanisms of cardioprotection in non-diabetic mice.

Methods

Adult C57BL/6 mice were randomized into four groups and orally received EMPA (10mg/kg/day), DAPA (9.0mg/kg/day), ERTU (9.7mg/kg/day) or vehicle (5% DMSO in water for injection) for 7 days. The doses of DAPA and ERTU were stoichiometrically equivalent to EMPA's dose that we have previously used as clinically relevant. On the 8th day, mice were subjected to 30' ischemia (I), following by 2h reperfusion (R) and IS was measured. Body weight and fasting blood glucose levels were determined at baseline and at the end of the treatment. Then, we sought to unveil the mechanistic differences among those drugs which are responsible for the observed cardioprotection. Additional mice were randomized into the four groups and were treated for 7 days, as described above. On the 8th day, mice were subjected to 30'I/10'R and the ischemic myocardium was collected. We focused on the cardioprotective signaling of SAFE and RISK pathways and we evaluated the phosphorylation and expression of STAT3, PI3K, Akt and eNOS. Also, we examined the gene expression levels of IL-6 and TGF-β as possible mediators of the SAFE pathway.

Results

Short term oral administration of EMPA and DAPA reduced myocardial IS (19.6%±2.6 EMPA, 18.0%±3.3 DAPA vs. 35.3%±1.7 Control, p<0.01). On the contrary, administration of ERTU did not reduce IS (30.3%±3.1 ERTU, p=NS). Body weight and glucose levels remained unchanged. Phosphorylation of STAT3(Y705) was increased at the 10th min of R in EMPA and DAPA groups, while was not altered by ERTU. Phosphorylation and expression of PI3K, Akt and eNOS did not differ among groups, indicating that the cardioprotective mechanism is independent of RISK pathway. Real time PCR analysis revealed that il-6 mRNA levels were not affected by the treatments. Notably, we observed increased mRNA levels of tgf-β in both EMPA and DAPA groups, which indicates that cardioprotection is mediated through STAT3/TGF-β crosstalk.

Conclusion(s)

Short-term EMPA and DAPA, but not ERTU treatment for 7 days reduces IS in healthy, non-diabetic mice through STAT3/TGF-β mediated pathways.

Funding Acknowledgement

Type of funding sources: None.

Automated Category and Trend Analysis of Scientific Articles on Ophthalmology Using Large Language Models: Development and Usability Study

BACKGROUND

In this paper, we present an automated method for article classification, leveraging the power of large language models (LLMs).

OBJECTIVE

The aim of this study is to evaluate the applicability of various LLMs based on textual content of scientific ophthalmology papers.

METHODS

We developed a model based on natural language processing techniques, including advanced LLMs, to process and analyze the textual content of scientific papers. Specifically, we used zero-shot learning LLMs and compared Bidirectional and Auto-Regressive Transformers (BART) and its variants with Bidirectional Encoder Representations from Transformers (BERT) and its variants, such as distilBERT, SciBERT, PubmedBERT, and BioBERT. To evaluate the LLMs, we compiled a data set (retinal diseases [RenD] ) of 1000 ocular disease-related articles, which were expertly annotated by a panel of 6 specialists into 19 distinct categories. In addition to the classification of articles, we also performed analysis on different classified groups to find the patterns and trends in the field.

RESULTS

The classification results demonstrate the effectiveness of LLMs in categorizing a large number of ophthalmology papers without human intervention. The model achieved a mean accuracy of 0.86 and a mean F1-score of 0.85 based on the RenD data set.

CONCLUSIONS

The proposed framework achieves notable improvements in both accuracy and efficiency. Its application in the domain of ophthalmology showcases its potential for knowledge organization and retrieval. We performed a trend analysis that enables researchers and clinicians to easily categorize and retrieve relevant papers, saving time and effort in literature review and information gathering as well as identification of emerging scientific trends within different disciplines. Moreover, the extendibility of the model to other scientific fields broadens its impact in facilitating research and trend analysis across diverse disciplines.

A qualitative exploration of the barriers and facilitators to the implementation of the alcohol assertive outreach model

Alcohol use disorder has adverse implications for individuals' health, utilisation of healthcare services, and societal costs. There are a group of individuals who frequently attend hospital for alcohol-related issues, have complex co-morbid needs, and experience barriers to engaging with specialised alcohol treatment services. To support these individuals and reduce healthcare system costs, Alcohol Assertive Outreach Treatment (AAOT) has been recommended. However, AAOT is not routinely used in the UK. Understanding the determinants of the implementation of AAOT can increase its utilisation and effectiveness. This study therefore employed the Consolidated Framework for Implementation Research (CFIR) framework to highlight barriers and facilitators to the successful and sustainable implementation of AAOT. Semi-structured interviews were conducted with twenty AAOT team staff members (team managers and outreach workers) from two North West England AAOT teams. Twenty-eight stakeholders (clinicians, commissioners, policy makers and academics across England) were also interviewed, who were considered to be key contributors to AAOT implementation, both within and external to North West England. Framework analysis based on the CFIR was conducted, whilst allowing for inductive coding where appropriate. Overall, participants recognised AAOT as acceptable and beneficial. Three main themes were identified: organisational and individual level factors, including team culture and staff characteristics; systemic partnerships and interagency communication; and an adaptable model driven by research and evaluation. Each theme relates to various CFIR domains and constructs which were perceived to influence the implementation of AAOT. Readers are encouraged to consider the findings in the development and implementation of AAOT teams, new or existing.

Endothelial Protection by Sodium-Glucose Cotransporter 2 Inhibitors: A Literature Review of In Vitro and In Vivo Studies

Endothelial dysfunction often precedes the development of cardiovascular diseases, including heart failure. The cardioprotective benefits of sodium-glucose cotransporter 2 inhibitors (SGLT2is) could be explained by their favorable impact on the endothelium. In this review, we summarize the current knowledge on the direct in vitro effects of SGLT2is on endothelial cells, as well as the systematic observations in preclinical models. Four putative mechanisms are explored: oxidative stress, nitric oxide (NO)-mediated pathways, inflammation, and endothelial cell survival and proliferation. Both in vitro and in vivo studies suggest that SGLT2is share a class effect on attenuating reactive oxygen species (ROS) and on enhancing the NO bioavailability by increasing endothelial nitric oxide synthase activity and by reducing NO scavenging by ROS. Moreover, SGLT2is significantly suppress inflammation by preventing endothelial expression of adhesion receptors and pro-inflammatory chemokines in vivo, indicating another class effect for endothelial protection. However, in vitro studies have not consistently shown regulation of adhesion molecule expression by SGLT2is. While SGLT2is improve endothelial cell survival under cell death-inducing stimuli, their impact on angiogenesis remains uncertain. Further experimental studies are required to accurately determine the interplay among these mechanisms in various cardiovascular complications, including heart failure and acute myocardial infarction.

The role of glucose in cardiac physiology and pathophysiology

PURPOSE OF REVIEW

Heart failure is one of the major causes of death worldwide and continues to increase despite therapeutics and pharmacology advances. Fatty acids and glucose are used as ATP-producing fuels in heart to meet its energy demands. However, dysregulation of metabolites' use plays a pivotal role in cardiac diseases. How glucose becomes toxic or drives cardiac dysfunction is incompletely understood. In the present review, we summarize the recent findings on cardiac cellular and molecular events that are driven by glucose during pathologic conditions and potential therapeutic strategies to tackle hyperglycemia-mediated cardiac dysfunction.

RECENT FINDINGS

Several studies have emerged recently, demonstrating that excessive glucose utilization has been correlated with impairment of cellular metabolic homeostasis primarily driven by mitochondrial dysfunction and damage, oxidative stress, and abnormal redox signaling. This disturbance is associated with cardiac remodeling, hypertrophy, and systolic and diastolic dysfunction. Both human and animal heart failure studies, report that glucose is a preferable fuel at the expense of fatty acid oxidation during ischemia and hypertrophy, but the opposite happens in diabetic hearts, which warrants further investigation.

SUMMARY

A better understanding of glucose metabolism and its fate during distinct types of heart disease will contribute to developing novel therapeutic options for the prevention and treatment of heart failure.

Cardioprotection by selective SGLT2 inhibitors in a non-diabetic mouse model of myocardial ischemia/reperfusion injury: a class or a drug effect?

Background

Empagliflozin (EMPA), Dapagliflozin (DAPA) and Ertugliflozin (ERTU) are selective sodium glucose co-transporter 2 inhibitors (SGLT2i) acting against type 2 diabetes mellitus.

Purpose

Due to differences in clinical trial outcomes, we aimed to 1) compare the cardioprotective effects of selective SGLT2i in terms of infarct size (IS) reduction and 2) reveal the mechanism of cardioprotection in non-diabetic mice.

Methods

C57BL/6 mice were randomized and orally received EMPA (10mg/kg/day), DAPA (9.0mg/kg/day), ERTU (9.7mg/kg/day) or vehicle for 7 days. IS was measured after 30' ischemia (I), and 120' reperfusion (R). EMPA, DAPA and ERTU were given at equivalent stoichiometrically doses (ESD). Body weight and fasting blood glucose (FBG) levels were determined at baseline and at the end of the treatment. On the 7th day, mice were housed in metabolic cages for 24 hours. Urine volume (UV), food and water uptake and 24h-glucose levels were determined to examine the extend of SGLT-2 inhibition by the drugs. In a second series, the ischemic myocardium was taken (10'R), shotgun proteomics were performed and several cardioprotective pathways were evaluated. In a third series, the dominant pathways were evaluated through molecular analyses and mitochondrial functionality. The causal relationships in the mechanism of protection, was established by inhibiting the concomitant cardioprotective pathways. Static, the specific STAT-3 inhibitor and wortmannin (a PI3K inhibitor) were administered and IS was measured upon 30'I/120' R.

Results

EMPA and DAPA but not ERTU reduced IS at this dose. Body weight and FBG levels were not affected by the treatments. EMPA, DAPA and ERTU lead to significant increase in UV and urinary glucose levels compared to the control group independently of the water and food intake. There was no significant difference in the parameters among the different SGLT-2i indicating that the chosen doses are sufficient to produce the same pharmacological SGLT-2 inhibition in mice. Proteomics revealed mitochondrial metabolism and NF-kB signaling as significant. Only EMPA preserved mitochondrial functionality in complex I & II linked oxidative phosphorylation. NF-kB, RISK and STAT-3 activation and the downstream reduction in apoptosis were evident in EMPA and DAPA groups coinciding with IS reduction. Static and wortmannin significantly attenuated IS reduction both in EMPA and DAPA groups indicating that STAT-3 and PI3K activation are the leading mechanisms of cardioprotection. Among several upstream mediators, fibroblast growth factor 2 (FGF-2) and caveolin-3 were increased in EMPA and DAPA groups.

Conclusions

Short term EMPA, DAPA and ERTU at the chosen ESD inhibit SGLT-2i in a similar extent but only EMPA and DAPA reduce IS. Our study reveals drug specific effects on cardioprotection against I/R injury. Cardioprotection afforded by EMPA and DAPA are STAT-3 and PI3K dependent and associated with increased FGF-2 and Cav-3 expression.

Funding Acknowledgement

Type of funding sources: None.

Empagliflozin in Acute Myocardial Infarction Reduces No-Reflow and Preserves Cardiac Function by Preventing Endothelial Damage

Empagliflozin treatment before acute myocardial infarction mainly targets the endothelial cell transcriptome. Empagliflozin treatment before and after myocardial infarction decreased no reflow and microvascular injury, leading to reduced infiltration of inflammatory cells, reduced infarct size, and improved cardiac function in mice. In diabetic patients receiving empagliflozin after myocardial infarction, perfused boundary region, flow-mediated dilation, and global longitudinal strain were improved.