Aldose Reductase as a Key Target in the Prevention and Treatment of Diabetic Retinopathy: A Comprehensive Review

The escalating global prevalence of diabetes mellitus (DM) over the past two decades has led to a persistent high incidence of diabetic retinopathy (DR), necessitating screening for early symptoms and proper treatment. Effective management of DR aims to decrease vision impairment by controlling modifiable risk factors including hypertension, obesity, and dyslipidemia. Moreover, systemic medications and plant-based therapy show promise in advancing DR treatment. One of the key mechanisms related to DR pathogenesis is the polyol pathway, through which aldose reductase (AR) catalyzes the conversion of glucose to sorbitol within various tissues, including the retina, lens, ciliary body and iris. Elevated glucose levels activate AR, leading to osmotic stress, advanced glycation end-product formation, and oxidative damage. This further implies chronic inflammation, vascular permeability, and angiogenesis. Our comprehensive narrative review describes the therapeutic potential of aldose reductase inhibitors in treating DR, where both synthetic and natural inhibitors have been studied in recent decades. Our synthesis aims to guide future research and clinical interventions in DR management.

Evaluating the Role of Breast Ultrasound in Early Detection of Breast Cancer in Low- and Middle-Income Countries: A Comprehensive Narrative Review

Breast cancer, affecting both genders, but mostly females, exhibits shifting demographic patterns, with an increasing incidence in younger age groups. Early identification through mammography, clinical examinations, and breast self-exams enhances treatment efficacy, but challenges persist in low- and medium-income countries due to limited imaging resources. This review assesses the feasibility of employing breast ultrasound as the primary breast cancer screening method, particularly in resource-constrained regions. Following the PRISMA guidelines, this study examines 52 publications from the last five years. Breast ultrasound, distinct from mammography, offers advantages like radiation-free imaging, suitability for repeated screenings, and preference for younger populations. Real-time imaging and dense breast tissue evaluation enhance sensitivity, accessibility, and cost-effectiveness. However, limitations include reduced specificity, operator dependence, and challenges in detecting microcalcifications. Automatic breast ultrasound (ABUS) addresses some issues but faces constraints like potential inaccuracies and limited microcalcification detection. The analysis underscores the need for a comprehensive approach to breast cancer screening, emphasizing international collaboration and addressing limitations, especially in resource-constrained settings. Despite advancements, notably with ABUS, the primary goal is to contribute insights for optimizing breast cancer screening globally, improving outcomes, and mitigating the impact of this debilitating disease.

Differentiating Viral from Bacterial Pneumonia in Children: The Diagnostic Role of Lung Ultrasound-A Prospective Observational Study

This prospective observational study aimed to investigate the utility of lung ultrasound (LUS) in diagnosing and managing pediatric respiratory infections, specifically focusing on viral, bacterial, and SARS-CoV-2 infections. Conducted over a period of 1 year and 8 months, this research involved 85 pediatric patients (showcasing a median age of 14 months) recruited based on specific criteria, including age, confirmed infection through multiplex PCR tests, and willingness to undergo LUS imaging. This study employed a 12-area scoring system for LUS examinations, utilizing the lung ultrasound score (LUSS) to evaluate lung abnormalities. The PCR examination results reveal diverse respiratory pathogens, with SARS-CoV-2, influenza, and bacterial co-infections being prominent among the cases. As an observational study, this study was not registered in the registry. Distinct LUS patterns associated with different pathogens were identified, showcasing the discriminatory potential of LUS in differentiating between viral and bacterial etiologies. Bacterial infections demonstrated more severe lung involvement, evident in significantly higher LUSS values compared with viral cases (p < 0.0001). The specific abnormalities found in bacterial superinfection can be integrated into diagnostic and management protocols for pediatric respiratory infections. Overall, this research contributes valuable insights into optimizing LUS as a diagnostic tool in pediatric pneumonia, facilitating more informed and tailored healthcare decisions.

Stratifying Disease Severity in Pediatric COVID-19: A Correlative Study of Serum Biomarkers and Lung Ultrasound-A Retrospective Observational Dual-Center Study

The COVID-19 pandemic, caused by SARS-CoV-2, has manifested distinct impacts on infants and children. This study delves into the intricate connection between lung ultrasound (LUS) findings and serum biomarkers in neonates and infants with COVID-19. Exploring factors contributing to the mild symptoms in this demographic, including immune responses and pre-existing immunity, the study spans 3 years and 9 months, involving 42 patients. Respiratory and gastrointestinal symptoms predominate, and LUS emerges as a vital, non-irradiating tool for evaluating pulmonary abnormalities. Serum biomarkers like CRP, procalcitonin, and cytokines provide key insights into the pathophysiology. Correlations reveal nuanced links between LUS score and clinical parameters, unveiling associations with hospitalization duration (rho = 0.49), oxygen saturation (rho = -0.88), and inflammatory markers, like ferritin (rho = 0.62), LDH (rho = 0.73), and D-dimer (rho = 0.73) with significance level (p < 0.05). The absence of large consolidations in LUS suggests unique pulmonary characteristics. The novelty of these findings lies in the comprehensive integration of LUS with serum biomarkers to assess and monitor the severity of lung involvement in neonates and infants affected by SARS-CoV-2. This approach offers valuable insights into disease severity, biomarker levels, the duration of hospitalization, and oxygen saturation, providing a multifaceted understanding of COVID-19's impact on this vulnerable population.

Tiny Lungs, Big Differences: Navigating the Varied COVID-19 Landscape in Neonates vs. Infants via Biomarkers and Lung Ultrasound

Due to their susceptibilities, neonates and infants face unique SARS-CoV-2 challenges. This retrospective study will compare the illness course, symptoms, biomarkers, and lung damage in neonates and infants with SARS-CoV-2 infection from February 2020 to October 2023. This study was conducted at two hospitals in Timisoara, Romania, using real-time multiplex PCR to diagnose and lung ultrasonography (LUS) to assess lung involvement. Neonates had a more severe clinical presentation, an increased immune response, and greater lung involvement. Neonates had more PCR-positive tests (p = 0.0089) and longer hospital stays (p = 0.0002). In neonates, LDH, CRP, and ferritin levels were higher, indicating a stronger inflammatory response. Reduced oxygen saturation in neonates indicates respiratory dysfunction. The symptoms were varied. Infants had fever, cough, and rhinorrhea, while neonates had psychomotor agitation, acute dehydration syndrome, and candidiasis. This study emphasizes individualized care and close monitoring for neonatal SARS-CoV-2 infections. Newborn lung ultrasonography showed different variances and severity levels, emphasizing the need for targeted surveillance and therapy. Newborns have high lung ultrasound scores (LUSS), indicating significant lung involvement. Both groups had initial lung involvement, but understanding these modest differences is crucial to improving care for these vulnerable populations.

Current Trends in Diagnosis and Treatment Approach of Diabetic Retinopathy during Pregnancy: A Narrative Review

Diabetes mellitus during pregnancy and gestational diabetes are major concerns worldwide. These conditions may lead to the development of severe diabetic retinopathy during pregnancy or worsen pre-existing cases. Gestational diabetes also increases the risk of diabetes for both the mother and the fetus in the future. Understanding the prevalence, evaluating risk factors contributing to pathogenesis, and identifying treatment challenges related to diabetic retinopathy in expectant mothers are all of utmost importance. Pregnancy-related physiological changes, including those in metabolism, blood flow, immunity, and hormones, can contribute to the development or worsening of diabetic retinopathy. If left untreated, this condition may eventually result in irreversible vision loss. Treatment options such as laser therapy, intravitreal anti-vascular endothelial growth factor drugs, and intravitreal steroids pose challenges in managing these patients without endangering the developing baby and mother. This narrative review describes the management of diabetic retinopathy during pregnancy, highlights its risk factors, pathophysiology, and diagnostic methods, and offers recommendations based on findings from previous literature.

COVID-19 in Infants and Children under 2 Years-Could Lung Ultrasound Score Be Correlated with Biomarkers and Symptoms?

INTRODUCTION

It is already well known that infants and children infected with COVID-19 develop mild to moderate forms of the disease, with fever and oropharyngeal congestion being the most common symptoms. However, there are instances when patients claim to be experiencing respiratory symptoms. Because of the repeated lung examinations required in these situations, non-irradiating imaging techniques are preferred. This study's objective is to ascertain the value of lung ultrasonography (LUS) in the medical management of these specific cases.

METHODS

Infants and children under two years old with SARS-CoV-2 infection were evaluated using LUS. Patients with other respiratory pathologies were excluded by using specific tests. The LUS score (LUSS) was correlated with biomarkers and clinical findings using the Mann-Whitney U test and Spearman's rank correlation rho.

RESULTS

The LUSS for each patient varied from 1 to 8 points out of a maximum of 36 points. The arithmetic mean was 4.47 ± 2.36 (S.D), while the 95% CI for the arithmetic mean was 3.33 to 5.61. Sparse B-lines were present in all enrolled infants and children (100%), while only 36.84% developed alveolar syndrome (confluent B-lines). The lung changes were correlated with their biomarkers, specifically inflammatory markers. The correlation between LUSS and LDH, D-dimers, and IL-6 was a strongly positive one with rho = 0.55 (p = 0.001, 95% CI 0.13 to 0.80) between the LUSS and D-dimer levels and rho = 0.60 (p = 0.03, 95% CI 0.04 to 0.87) between LUSS and D-dimer levels at symptomatic infants and children (with respiratory involvement).

CONCLUSIONS

Infants and children under the age of two are prone to develop mild forms of COVID-19 disease with a B-line pattern on LUS, although inflammatory markers have elevated blood levels. Despite the small sample, D-dimer levels and O2 saturation were correlated with LUSS in patients with respiratory involvement, while similar results were also found in the entire lot.

Hepatic arterial variations detected at multidetector computer tomography angiography in the Romanian population

BACKGROUND

Our purpose was to determine the prevalence of normal hepatic vascularization and variations of the hepatic arteries using multidetector computed tomography (MDCT) angiography. These variants should be known before any surgery of the upper abdomen, the downside being that there aren't many studies on large groups of patients using high-specialized imaging.

MATERIALS AND METHODS

This study was carried out on 4192 patients. We performed MDCT angiography on each one of the patients and had a specialized team observe the images.

RESULTS

Using Michels' classification, the normal anatomy (type I) was present in 3392 (80.91%) cases, while abnormal hepatic arteries were observed in 800 (19.08%) cases. The variations were distributed as follows: type II in 40 (0.95%) cases, type III in 442 (10.54%) cases, type IV in 13 (0.31%) cases, type V in 285 (6.79%) cases, type VI in 12 (0.28%) cases, type VII in 3 (0.07%) cases, type VIII in 108 (2.57%) cases, type IX in 6 (0.14%) cases and type X in one case (0.02%). 170 (4.05%) unclassified cases were observed. Using Hiatt's classification, the variations were: type II in 325 (7.75%) cases, type III in 454 (10.83%) cases, type IV in 124 (2.95%) cases, type V in 6 cases (0.14%) and type VI in 69 (1.64%) cases. 102 (2.43%) unclassified cases were observed.

CONCLUSIONS

We observed well-known variations of the hepatic arterial pattern and also found a large number of rare, unclassified cases.

Could Biparametric MRI Replace Multiparametric MRI in the Management of Prostate Cancer?

Prostate cancer (PCa) is a worldwide epidemiological problem, since it is one of the most prevalent types of neoplasia among men, and the third-leading cause of cancer-related deaths, after lung and colorectal tumors. Unfortunately, the early stages of PCa have a wide range of unspecific symptoms. For these reasons, early diagnosis and accurate evaluation of suspicious lesions are crucial. Multiparametric MRI (mpMRI) is currently the imaging modality of choice for diagnostic screening and local staging of PCa, but also has a leading role in guiding biopsies and in treatment biparametric MRI (bpMRI) could partially replace mpMRI due to its lack of adverse reactions caused by contrast agents, relatively lower costs, and shorter acquisition time. Further, 31 relevant articles regarding the advantages and disadvantages of the aforementioned imaging techniques were scanned. As a result, while bpMRI has comparable accuracy in detecting PCa, its roles in the other steps of PCa management are limited.

Breast Cancer—How Can Imaging Help?

Breast cancer is the most common malignant disease among women, causing death and suffering worldwide. It is known that, for the improvement of the survival rate and the psychological impact it has on patients, early detection is crucial. For this to happen, the imaging techniques should be used at their full potential. We selected and examined 44 articles that had as subject the use of a specific imaging method in breast cancer management (mammography, ultrasound, MRI, ultrasound-guided biopsy, PET-CT). After analyzing their data, we summarized and concluded which are the best ways to use each one of the mentioned techniques for a good outcome. We created a simplified algorithm with easy steps that can be followed by radiologists when facing this type of neoplasia.

Is Lung Ultrasound Helpful in COVID-19 Neonates?-A Systematic Review

Background: The SARS-CoV-2 infection has occurred in neonates, but it is a fact that radiation exposure is not recommended given their age. The aim of this review is to assess the evidence on the utility of lung ultrasound (LUS) in neonates diagnosed with COVID-19. Methods: A systematic literature review was performed so as to find a number of published studies assessing the benefits of lung ultrasound for newborns diagnosed with COVID and, in the end, to make a comparison between LUS and the other two more conventional procedures of chest X-rays or CT exam. The key terms used in the search of several databases were: “lung ultrasound”, “sonography”, “newborn”, “neonate”, and “COVID-19′. Results: In total, 447 studies were eligible for this review, and after removing the duplicates, 123 studies referring to LU were further examined, but only 7 included cases of neonates. These studies were considered for the present research paper. Conclusions: As a non-invasive, easy-to-use, and reliable method for lung lesion detection in neonates with COVID-19, lung ultrasound can be used as a useful diagnosis tool for the evaluation of COVID-19-associated lung lesions. The benefits of this method in this pandemic period are likely to arouse interest in opening new research horizons, with immediate practical applicability.

Updated Incidence of Thyroid Cancer in the North East Region of Romania after 35 Years of Chernobyl Fallout. Is There a Link between?

Thyroid cancer (TC) represents a worldwide problem, the consistent growth of the incidence increment issues about management of risk factors and curative treatment. Updated statistical data are not complete in the North East region of Romania and need to be improved. Therefore, through this study, we aim to renew the existing data on thyroid cancer. We conducted a retrospective study covering a period of 10 years. Data were collected from a hospital information system (InfoWorld) between 2009 and 2019. Patients' age groups were stratified in relation with the age at the moment of the Chernobyl event. A database was obtained (Microsoft Excel) and statistical correlations were applied. In the studied period, 1159 patients were diagnosed: 968 females and 191 males, distributed by region, with the highest addressability in Iasi (529), followed by neighboring counties. Age distribution displayed that most of the thyroid cancers were in the range 4060 years old (50.94%), followed by 60-80 years old (32.41%). Most patients were diagnosed with papillary carcinoma 63.10%, then follicular 14.7%, medullary 6.74% and undifferentiated 1.02%. Romania was in the vicinity of the radioactive cloud at Chernobyl fallout, so we must deliberate whether the increased incidence of thyroid cancer in the age group 40-60 years is associated with radiogenicity (iodine 131) given the fact that over has 35 years and the half-life of other radioisotopes like Caesium-137 and Strontium -90 is completed.

Adalimumab and Infliximab in Crohn's disease - real life data from a national retrospective cohort study

AIM

to compare the efficacy and safety of Adalimumab(ADA) and Infliximab(IFX), in a large Romanian population and to identify predictors of response. Methods We performed a national retrospective cohort study including 265 patients (136 ADA, 129 IFX) between 2008-2014. Binary logistic regression was performed with the statistical program Minitab.

RESULTS

Patients were half women, with a median age of 36, a median disease duration of 2.5 years, 80% received Azathioprine. Mean therapy duration was 20 months in ADA group and 36 months in IFX group. Complete response to Adalimumab respectively Infliximab was recorded in 77%vs.65%, secondary loss of response in 18%vs.28%, statistically comparable. We failed to identify predictors of response. In 79.2%of patients with secondary loss of response to ADA, the dose was escalated, 12.5% were switched to Infliximab. In 70%of patients that lost response to IFX, the dose was increased, 30% were switched to Adalimumab.

CONCLUSIONS

Adalimumab and Infliximab have similar efficacy, with a complete response rate of~70%. In case of secondary loss of response to IFX, the best solution is to switch to ADA, with 83% response rate, while in case of secondary loss of response to ADA, increasing the dose leads to 84 % response rate.

Nutritional risk screening and prevalence of malnutrition on admission to gastroenterology departments: a multicentric study

BACKGROUND AND AIMS

There is little awareness and a lack of data on the prevalence of hospital malnutrition in gastro-enterology departments. Since part of these patients are referred for surgical treatment and poor nutritional status is a known risk factor for perioperative morbidity, we conducted a prospective study aimed to screen for the nutritional risk and assess the prevalence and risk factors of malnutrition in gastro-enterology departments in Romania.

METHODS

We included patients consecutively admitted to 8 gastroenterology units over a period of three months in our study. Nutritional risk was evaluated using NRS 2002. Malnutrition was defined using BMI ( 20 kg m2) or and 10% weight loss in the last six months.

RESULTS

3198 patients were evaluated, 51.6% males and 48.4% females, with the mean age of 54.5 Â+- 14.3 years. Overall percentage of patients at nutritional risk was 17.1%, with the highest risk for patients with advanced liver diseases (49.8%), oncologic (31.3%), inflammatory bowel diseases (20.2%), and pancreatic diseases (18.9%). The overall prevalence of malnutrition was of 20.4%, higher for advanced liver diseases (39.4%), inflammatory bowed diseases (30.6%), oncologic (26.8%) and pancreatic diseases (23%). Independent risk factors for malnutrition were younger age (p 0.0001), female gender (p 0.0001), a higher (A ≥ 3) NRS (p 0.0001), presence of neoplasm (p 0.0001), of advanced liver disease (p=0.0003) and a reduction of 25% of dietary intake (p 0.0001).

CONCLUSIONS

One in five patients admitted to gastroenterology units could benefit from prompt nutritional intervention. Correction of nutritional status is mandatory before any surgical procedure. Emphasis on nutritional evaluation at admission and beginning of nutritional therapy where needed are particularly required in patients with advanced liver diseases, digestive neoplasms, inflammatory bowel diseases and pancreatic diseases.

ABBREVIATIONS

NRS= nutritional risk score, BMI = body mass index, IBD = inflammatory bowel diseases.

Outcome of liver transplantation for hepatocellular carcinoma -- a single center experience

BACKGROUND & AIMS

Liver transplantation (LT) is a promising treatment for patients with liver cirrhosis associated with hepatocellular carcinoma (HCC). The aim of our study was to evaluate our experience regarding the clinical and pathological staging of HCC in patients who underwent LT, as well as recurrence free and overall survival.

METHODS

From January 2006 to December 2011, 38 patients with diagnosis of HCC, underwent LT in our Center. Demographic, clinical, imaging and pathologic information were recorded. A Cox proportional hazards survival analysis was performed in order to identify significant predictors of tumor recurrence and patient's death after LT.

RESULTS

Eighteen patients (47.4%) in our study group were within Milan criteria. The mean follow-up was 22 months and the recurrence rate of HCC after LT was 13.2%. The 1, 3- year recurrence free survival rates were 85%, 74.3% respectively. The 1 and 3-year overall survival rates were 83.5% and 63.6% respectively. No significant predictor for HCC recurrence was identified in our study group by survival analysis, taking into account 13 different variables. As independent predictors of patient'ss death after LT for HCC however, the presence of diabetes mellitus (p=0.001), presence of more than 3 HCC nodules (p=0.03) and tumor recurrence after LT (p=0.03) were identified by multivariate Cox proportional hazards survival analysis.

CONCLUSION

In our cohort HCC recurrence rate after LT was 13.2%. Diabetes mellitus, presence of more than 3 HCC nodules and HCC recurrence were significant predictors of poor overall survival after LT.

Abstract 2221: Enhanced SH3:linker interaction allosterically sensitizes Abl kinases to small molecule inhibitors

Bcr-Abl is the oncogenic protein-tyrosine kinase responsible for the pathogenesis of chronic myelogenous leukemia (CML). Clinical management of CML has been revolutionized by imatinib, a selective ATP-competitive inhibitor of Bcr-Abl kinase activity. Imatinib selectivity is due in part to its ability to recognize and stabilize the inactive conformation of the kinase domain. This conformation is stabilized by intramolecular binding of the SH3 domain to the

SH2-kinase linker, which in turn packs against the back of the kinase domain. Imatinib resistance can be caused by point mutations that either affect drug binding directly (e.g., through mutation of the gatekeeper position, Thr315) or that allosterically disturb the downregulated kinase domain conformation (e.g., through mutation or phosphorylation of the SH3 domain). These observations suggest that strengthening the regulatory SH3:linker interaction present in

Bcr-Abl may stabilize a downregulated kinase domain conformation, thus sensitizing the kinase domain to inhibitor action. To explore this possibility, we created a series of modified c-Abl and Bcr-Abl proteins with enhanced

SH3-linker interactions. By systematically increasing the proline content of the linker, we identified high-affinity linkers that stabilized intramolecular

SH3 binding without disturbing the overall regulation of the kinase core.

Enhanced SH3:linker interaction completely reversed c-Abl core activation by a

C-lobe myristate binding pocket mutation, and substantially reduced activation by mutations in the ATP binding site (T315I) as well as the SH2:C-lobe interface (Y158D). Remarkably, enhanced SH3:linker interaction dramatically sensitized Bcr-Abl not only to imatinib but also to the myristic acid binding pocket inhibitor, GNF-2. These effects were observed in the context of both wild-type and imatinib-resistant forms of Bcr-Abl. Hydrogen exchange mass spectrometry of recombinant Abl core proteins with high-affinity linkers revealed dynamic coupling between the SH3:linker interface, the GNF-2 binding site in the C-lobe myristate binding pocket, and the active site.

Taken together, these studies provide strong evidence that regulatory

SH3:linker interaction is retained in the context of Bcr-Abl, and supports the idea that small molecules enhancing natural regulatory interaction at the

SH3:linker interface may have utility as chemical sensitizers of Bcr-Abl drug action in the kinase domain.

Citation Format: Shoghag B. Panjarian, Roxana Iacob, Chen Shugui, Thomas Wales, John R. Engen, Thomas E. Smithgall. Enhanced SH3:linker interaction allosterically sensitizes Abl kinases to small molecule inhibitors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2221. doi:10.1158/1538-7445.AM2013-2221

Abstract 5599: Allosteric regulation of Abl and Bcr-Abl kinases by enhanced SH3:linker interaction

Bcr-Abl is the oncogenic protein-tyrosine kinase responsible for the pathogenesis of chronic myelogenous leukemia (CML). Clinical management of CML has been revolutionized by imatinib, a selective ATP-competitive inhibitor of Bcr-Abl kinase activity. Despite the clinical success of imatinib in the chronic stage of CML, it is less effective in advanced disease due to the emergence of drug resistance often caused by point mutations in the Bcr-Abl kinase domain. Recently, we demonstrated that introduction of the “gatekeeper” resistance mutation T315I into a recombinant c-Abl “core” protein enhanced basal kinase activity. Imatinib selectivity is achieved in part by binding and stabilizing the unique inactive conformation of the Abl kinase domain. This conformation is stabilized allosterically by intramolecular binding of the SH3 domain to the SH2-kinase linker, which in turn docks against the back of the kinase domain. The goal of this project, therefore, was to determine whether kinase activation induced by T315I, as well as a mutation in a recently described allosteric inhibitor binding site in the kinase domain C-lobe (A356N mutant), could be overcome by enhancing the SH3:linker interaction. For these experiments, we engineered nine High Affinity Linker (HAL) variants of Abl in which SH3:linker interaction was tightened through sequential addition of proline residues to the linker. Enhanced SH3:linker interaction was confirmed by analysis of SH3 dynamics using hydrogen-deuterium exchange mass spectrometry. Using cell based assays, we identified Abl-HAL core proteins that remain locked in an inactive conformation. To determine the impact of the HAL sequences on activating mutations in the kinase domain, the strongest HAL sequence was combined with the T315I and A356N mutations. Remarkably, the HAL substitution completely reversed Abl core activation by the A356N mutation, and partially reversed the effect of T315I. We next introduced the HAL sequence into p210 Bcr-Abl coding region (wild-type and T315I), and expressed these forms of Bcr-Abl along with matched controls in the human myeloid cell line, TF-1. The Bcr-Abl HAL mutants transformed TF-1 cells to a cytokine-independent phenotype as effectively as wild-type Bcr-Abl but were much more sensitive to induction of apoptosis by the allosteric inhibitor, GNF-2. Furthermore, TF-1 cells transformed with Bcr-Abl-HAL bearing a wild-type kinase domain also showed greater sensitivity to imatinib and the related inhibitor nilotinib, suggesting that enhanced SH3:linker interaction structures the kinase domain in a favorable conformation for drug action. Our results provide new evidence that SH3:linker interaction not only has a strong allosteric effect on the regulation of the c-Abl kinase core, but also on Bcr-Abl sensitivity to both ATP-competitive and allosteric inhibitors as well.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5599. doi:1538-7445.AM2012-5599

Abstract B75: Allosteric regulation of Abl and Bcr-Abl kinases by enhanced SH3:linker interaction

Bcr-Abl is the oncogenic protein-tyrosine kinase responsible for the pathogenesis of chronic myelogenous leukemia (CML). Clinical management of CML has been revolutionized by imatinib, a selective ATP-competitive inhibitor of Bcr-Abl kinase activity. Despite the clinical success of imatinib in the chronic stage of CML, it is less effective in advanced disease due to the emergence of drug resistance often caused by point mutations in the Bcr-Abl kinase domain. Recently, we demonstrated that introduction of the “gatekeeper” resistance mutation T315I into a recombinant c-Abl “core” protein (consisting of the myristoylated N-Cap, SH3, SH2 and kinase domains) enhanced basal kinase activity. Imatinib selectivity is achieved in part by binding and stabilizing the unique inactive conformation of the Abl kinase domain. This conformation is stabilized allosterically by intramolecular binding of the SH3 domain to the SH2-kinase linker, which in turn docks against the back of the kinase domain. The goal of this project, therefore, was to determine whether kinase activation induced by T315I, as well as a mutation in a recently described allosteric inhibitor binding site in the kinase domain C-lobe (A356N mutant), could be overcome by enhancing the SH3:linker interaction. For these experiments, we engineered ten recombinant High Affinity Linker (HAL) proteins based on the c-Abl regulatory region (SH3-SH2-Linker) in which SH3:linker interaction was tightened through sequential addition of proline residues to the linker. Enhanced SH3:linker interaction was confirmed by analysis of SH3 dynamics using hydrogen-deuterium exchange mass spectrometry. We then incorporated the HAL coding sequences into the c-Abl core, and assessed kinase activation following transfection of 293T cells. Immunoblot analysis with autophosphorylation site-specific antibodies showed that five of the Abl-HAL core proteins remained inactive, suggesting that linker proline substitution did not alter the downregulated conformation. To determine the impact of the HAL sequences on activating mutations in the kinase domain, the strongest HAL sequence was combined with the T315I and A356N mutations. Remarkably, the HAL substitution completely reversed Abl core activation by the A356N mutation, and partially reversed the effect of T315I. We next introduced the HAL sequence into p210 Bcr-Abl coding region (wild-type and T315I), and expressed these forms of Bcr-Abl along with matched controls in the human myeloid leukemia cell line, TF-1. The Bcr-Abl HAL mutants transformed TF-1 cells to a cytokine-independent phenotype as effectively as wild-type Bcr-Abl but were much more sensitive to induction of apoptosis by the allosteric inhibitor, GNF-2. Furthermore, TF-1 cells transformed with Bcr-Abl-HAL bearing a wild-type kinase domain also showed greater sensitivity to imatinib and the related inhibitor nilotinib, suggesting that enhanced SH3:linker interaction structures the kinase domain in a favorable conformation for drug action. Our results provide new evidence that SH3:linker interaction not only has a strong allosteric effect on the regulation of the c-Abl kinase core, but also on Bcr-Abl sensitivity to both ATP-competitive and allosteric inhibitors as well.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B75.

Abstract B165: Abl kinase myristate-site inhibitor, mechanism and application

We recently reported a new class of allosteric inhibitors, exemplified by GNF-2, that selectively inhibit the proliferation of Bcr-Abl dependent cells. Here we demonstrate, using selection for resistant Bcr-Abl clones, site-directed mutagenesis, affinity chromatography, and steady-state kinetics, that GNF-2 inhibits Bcr-Abl kinase activity by binding to the Abl myristate binding pocket and stabilizes the auto-inhibited conformation. We demonstrate that the 2-hydroxyethyl amide analog of GNF-2, GNF-5, in combination with ATP-competitive inhibitors such as nilotinib and dasatinib can overcome the T315I “gatekeeper” mutant of Bcr-Abl which is resistant to all clinically approved Bcr-Abl inhibitors. These studies demonstrate that targeting of the Abl myristate binding site can provide an important pharmacological means to overcome mutations that cause resistance to ATP-competitive inhibitors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B165.

MELD exceptions and new predictive score of death on long waiting lists for liver transplantation

BACKGROUND

Cirrhosis related complications, considered MELD exceptions, proved to add prognostic value to the MELD score in predicting waiting list mortality.

AIM

To identify the predictive value for death on a long waiting list (WL) for the complications of liver disease.

METHODS

During 2004-2007, 372 consecutive adult patients were listed for liver transplantation (LT). To identify the potential predictors of patient death, univariate and multivariate Cox's proportional hazards regression model was used.

RESULTS

In the univariate survival analysis the following variables were significant: spontaneous bacterial peritonitis, refractory ascites, hyponatremia, hepatic encephalopathy, hepatorenal syndrome, initial and current MELD score, initial and current Child-Pugh score. The independent predictors of death on our WL were: refractory ascites (p=0.002) and hepatorenal syndrome (p=0.002). Based on a logistic regression analysis a new score has been developed: Score = 1/(1+ exp(-(-4.38 + 1.34 x Refractory ascites + 0.9 x Hepatorenal syndrome + 0.15 x Current MELD). The c-statistic for the new score for prediction of death on the WL was 0.85 compared to 0.80 for current MELD score.

CONCLUSION

Refractory ascites and hepatorenal syndrome should add valuable points to the current MELD in order to better prioritize for LT patients included on long WL.

ABBREVIATIONS

Liver transplantation (LT), Model for End-Stage Liver Disease (MELD), waiting list (WL), United Network for Organ Sharing (UNOS), standard deviation (SD), receiver operating characteristic (ROC), hepatitis B virus (HBV), hepatocellular carcinoma (HCC), positive predictive value (PPV), negative predictive value (NPV), Child-Turcotte-Pugh (CTP), hepatic venous pressure gradient (HVPG).

Functional and structural characterization of factor Xa dimer in solution

Previous studies showed that binding of water-soluble phosphatidylserine (C6PS) to bovine factor Xa (FXa) leads to Ca2+-dependent dimerization in solution. We report the effects of Ca2+, C6PS, and dimerization on the activity and structure of human and bovine FXa. Both human and bovine dimers are 10(6)- to 10(7)-fold less active toward prothrombin than the monomer, with the decrease being attributed mainly to a substantial decrease in k(cat). Dimerization appears not to block the active site, since amidolytic activity toward a synthetic substrate is largely unaffected. Circular dichroism reveals a substantial change in tertiary or quaternary structure with a concomitant decrease in alpha-helix upon dimerization. Mass spectrometry identifies a lysine (K(270)) in the catalytic domain that appears to be buried at the dimer interface and is part of a synthetic peptide sequence reported to interfere with factor Va (FVa) binding. C6PS binding exposes K(351) (part of a reported FVa binding region), K(242) (adjacent to the catalytic triad), and K(420) (part of a substrate exosite). We interpret our results to mean that C6PS-induced dimerization produces substantial conformational changes or domain rearrangements such that structural data on PS-activated FXa is required to understand the structure of the FXa dimer or the FXa-FVa complex.

Stem cells therapies for gastrointestinal and liver diseases

Stem cells therapies represent a new field of biomedical science which could provide in the future the cure for diseases until now incurable. The present paper reviews current knowledge on key biological properties of stem cells with focus on hepatic and gastrointestinal stem cells and current applications of stem cells therapies in gastrointestinal and liver diseases. Potential clinical applications for stem cells therapies have been suggested from animal model trials in acute liver failure, inherited metabolic liver disease and endstage liver disease (cirrhosis). Hematopoietic autologous stem cells transplantation has already been successfully performed in patients with severe inflammatory bowel disease or patients with refractory celiac disease with aberrant T cells. Future stem cells therapies for gastrointestinal postoperative or Crohn's disease fistulas are currently under investigation. More research is needed for perfecting stem cells harvesting protocols from different sources, in vitro expansion and differentiation protocols which can be used in phase II and III clinical trials.

Confocal laser endomicroscopy and ultrasound endoscopy during the same endoscopic session for diagnosis and staging of gastric neoplastic lesions

INTRODUCTION

Confocal LASER endomicroscopy (CLE) is a newly developed endoscopic technique which allows subsurface in vivo histological assessment during ongoing endoscopy and targeted biopsies. Ultrasound endoscopy (EUS) is a useful tool in staging upper GI malignant lesions. We describe for the first time the use of both techniques during the same endoscopic session, in a pilot study, in order to increase the diagnostic yield of histological assessment and provide the staging of the gastric neoplastic lesions thus decreasing the time to therapeutic decision.

AIMS & METHODS

CLE has been performed with the Pentax EG-3870CIK confocal endomicroscope after a 5 ml intravenous 10% fluorescein injection; EUS has been performed subsequently, during the same endoscopic Propofol sedation session, using a standard radial EUS-scope.

RESULTS

Eleven patients have been investigated, 4 females, 7 males, mean age 59.7 +/- 12.3 years. The indication of CLE/EUS exploration was the presence of a gastric polypoid lesion in 37% of cases, atypical gastric ulcer in 27% of patients, gastric lymphoma 18%, suspicion of gastric cancer recurrence after resection 9% and infiltrating type gastric cancer 9%. Histological assessment after targeted biopsy has established the diagnosis of gastric adenocarcinoma in 55% of cases, gastric lymphoma in 18% of cases, gastric adenoma, gastric GIST and gastric foveolar hyperplasia in 9% of cases respectively. CLE has allowed targeted biopsies in 81.8% of cases. In 2 patients - one case with suspected recurrent gastric cancer after surgery and one case of gastric lymphoma, CLE has indicated normal gastric mucosa. The EUS evaluation has shown TO lesion in two cases, T1 in 3 cases, T2 in 3 cases, T3 in one case. The EUS evaluation showed in one gastric lymphoma patient a lesion interesting the mucosa and submucosa with regional adenopathy and a submucosal lesion with regional adenopathy in the other gastric lymphoma case. The therapeutic decision was surgery in 73% of cases, chemotherapy and follow-up in 18% of cases and follow-up in 9% of cases. No complications were registered during the CLE/EUS explorations.

CONCLUSION

CLE and EUS can be successfully associated during the same endoscopic session, for upper GI neoplastic lesions allowing targeted biopsies for histological assessment and disease staging for optimal therapeutic decision.

Successful induction of tolerance to infliximab in patients with Crohn's disease and prior severe infusion reactions

AIM

To appraise the tolerance and efficacy of an induction of tolerance protocol to infliximab permitting the re-administration of the drug to patients with Crohn's disease having had infusion reactions requiring suspension of treatment.

METHODS

Fourteen patients were included in the induction of tolerance protocol. Each infusion of infliximab (5 mg/kg) was divided into 11 escalating 15 min increments over a 3-h time period. The induction of tolerance procedure was repeated for subsequent infusions.

RESULTS

Ten patients (71.4%) received all the three infusions for the induction treatment. Nine (64.3%) had a significant response and six (48.8%) still benefited from infliximab infusions. Seven patients (50%) achieved a complete remission, after a mean of 2.5 (two to three) infusions. Four patients (28.6%) had no response and the protocol was stopped. Three patients (21.4%) experienced mild immediate hypersensitivity reactions, which were controlled, two patients (14.2%) experienced severe immediate hypersensitivity reactions, leading to interruption of the treatment and one patient developed a delayed hypersensitivity reaction.

CONCLUSION

Our induction of tolerance protocol allows some patients who have experienced severe or repetitive infusion reactions to infliximab to be safely retreated with the drug in a hospitalized setting, with a clinical response achieved in a majority of these patients.

Predictors of death on the waiting list for liver transplantation characterized by a long waiting time

The number of patients dying while on the liver transplantation (LT) waiting list (WL) has continued to increase in recent years as a result of severe shortage of organs. Therefore, it is important to evaluate the existing models that predict death on the WL and to determine the independent predictors of death. The study cohort comprised 152 adult patients listed for LT in our centre over a period of 2 years (January 2001 to January 2003). The 12-month survival rate has been calculated by Kaplan-Meier method. The survival analysis performed by Cox proportional hazard model has evaluated the three parameters which compose the model for end-stage liver disease (MELD) score. Forty-four patients (28.9%) died while listed for LT. The survival rate was 92% at 3 months, 80% at 6 months and 69% at 12 months. Median survival was not reached. MELD score was found to be an excellent predictor of death at 12 months on our WL--c-statistic (area under curve) 0.84. In our survival analysis, only international normalized (prothrombin) ratio (INR) and serum creatinine were identified as an independent predictors of death (P < 0.0001). A new simplified version of the MELD score, which does not include serum bilirubin, is proposed and its c-statistic as predictor for death on the WL at 12 months is 0.86, as good as the original MELD score, when evaluated on our list. There is a fourfold increase in mortality on our WL for LT between 3 and 12 months after the inclusion. A simplified version of the MELD score, using only serum creatinine and INR might be taken into account when predicting 12 months mortality on WL with longer waiting time, but it has to be confirmed by other prospective studies.