Martin Čulen

Designing a Dynamic Dissolution Method: A Review of Instrumental Options and Corresponding Physiology of Stomach and Small Intestine

Development of new pharmaceutical compounds and dosage forms often requires in vitro dissolution testing with the closest similarity to the human gastrointestinal (GI) tract. To create such conditions, one needs a suitable dissolution apparatus and the appropriate data on the human GI physiology. This review discusses technological approaches applicable in biorelevant dissolutions as well as the physiology of stomach and small intestine in both fasted and fed state, that is, volumes of contents, transit times for water/food and various solid oral dosage forms, pH, osmolality, surface tension, buffer capacity, and concentrations of bile salts, phospholipids, enzymes, and Ca(2+) ions. The information is aimed to provide clear suggestions on how these conditions should be set in a dynamic biorelevant dissolution test.

Quantitative assessment of the CD26+ leukemic stem cell compartment in chronic myeloid leukemia: patient-subgroups, prognostic impact, and technical aspects

Little is known about the function and phenotype of leukemic stem cells (LSCs) in chronic myeloid leukemia (CML) or about specific markers that discriminate LSCs from normal hematopoietic stem cells (HSCs). CD26 has recently been described as a specific marker of CML LSCs. In the current study, we investigated this marker in a cohort of 31 unselected CML patients. BCR/ABL1 positivity was analyzed in highly enriched stem cell fractions using fluorescence in situ hybridization (FISH) and reverse transcription PCR (RT-PCR). The proportion of CD26+ LSCs and CD26− HSCs varied considerably among the patients analyzed, and the percentage of CD26+ cells correlated with leukocyte count. The CD26 expression robustly discriminated LSCs from HSCs. This required a strict gating of the stem cell compartment. Thus, in patients with very low LSC or HSC numbers, only the highly sensitive RT-PCR method discriminated between clonal and non-clonal cells, while a robust FISH analysis required larger numbers of cells in both compartments. Finally, our data show that the numbers of CD26+ CML LSCs correlate with responses to treatment with BCR-ABL1 inhibitors.

The Fatigue Behaviour of Filament-Wound Fiberglass/Epoxy Tubes under Cyclic Pressure

An experimental study of the behaviour of multidirectional filament-wound fiberglass/epoxy tubes under cyclic loading is presented. Commercially wound tubes were investigated under a biaxial loading condition. Two series of tests were conducted with the different pressure ratios, R =pmin/pmax= 0.05 and R = 0.3. The results are discussed based on macroscopic and microscopic damage observed. The hysteresis loops are analyzed and fatigue life curves are constructed. The fatigue results for the two R-ratios are reduced into a single life curve with a narrow scatter band, by using an effective stress damage parameter.

Advances in dissolution instrumentation and their practical applications.

Abstract The rising demands on discriminatory and prediction abilities of dissolution methods and the increasing complexity of new drug products are the main driving forces of the progress in this field. The research moves forward as imperfections and shortcomings of classical methods are being described, and where the capabilities of the contemporary methods are insufficient, new methods are being developed. The review discusses these advances with respect to the issues that currently draw the most attention, i.e. correct simulation of hydrodynamics and stress forces, maintenance of sink conditions, study of precipitation, use of biorelevant media and the employment of more physiologically relevant methods in general.

Novel complex mutation in NPM1 gene in patient with acute myeloid leukemia

Somatic heterozygous mutations of the nucleophosmin gene (NPM1) are the most frequent mutations in acute myeloid leukemia (AML) patients. Mutations occur in approximately one-third of all adult patients with AML and in one half of cytogenetically normal AML patients (CN-AML). Mutations are mostly insertions that cluster within exon 11 – at the level of transcript (Ensembl transcript ref ENST00000296930, 1758 base pairs [bp]) it means within exon 12 – at the level of genomic DNA (Ensembl gene ref ENSG00000181163, NCBI Gene ref 4869 related to the Ensembl transcript ref ENST00000517671, 1338 bp). Frame shift mutations of the NPM1 gene cause the elongation of nucleophosmin phosphoprotein and its aberrant cytoplasmic expression.

Development of In Vitro-In Vivo Correlation/Relationship Modeling Approaches for Immediate Release Formulations Using Compartmental Dynamic Dissolution Data from “Golem”: A Novel Apparatus

Different batches of atorvastatin, represented by two immediate release formulation designs, were studied using a novel dynamic dissolution apparatus, simulating stomach and small intestine. A universal dissolution method was employed which simulated the physiology of human gastrointestinal tract, including the precise chyme transit behavior and biorelevant conditions. The multicompartmental dissolution data allowed direct observation and qualitative discrimination of the differences resulting from highly pH dependent dissolution behavior of the tested batches. Further evaluation of results was performed using IVIVC/IVIVR development. While satisfactory correlation could not be achieved using a conventional deconvolution based-model, promising results were obtained through the use of a nonconventional approach exploiting the complex compartmental dissolution data.

The influence of mutational status and biological characteristics of acute myeloid leukemia on xenotransplantation outcomes in NOD SCID gamma mice

PurposeThis study aimed at analyzing the association of gene mutations and other acute myeloid leukemia (AML) characteristics with engraftment outcomes in immunodeficient mice and to select the engraftment outcomes that best reflect patient survival.MethodsMutations in 19 genes as well as leukemia- and patient-related characteristics were analyzed for a group of 47 de novo AML samples with respect to three engraftment outcomes: engraftment ability, engraftment intensity (percentage of hCD45+ cells) and engraftment latency. Leukemia-related characteristics were additionally analyzed in an extended group of 68 samples that included the 47 de novo samples, and additional 21 samples from refractory and relapsed cases. Engraftment outcomes were compared with overall and event-free survival of the patients.ResultsFor the 47 de novo samples, no single mutation influenced engraftment, whereas the NPM1mut/DNMT3Amut co-mutation was associated with higher engraftment ability. NPM1mut/FLT3-ITDneg had lower engraftment intensity. Among leukemia-related characteristics, a complex karyotype was associated with higher engraftment intensity. Among patient-related characteristics, higher cytogenetic risk was associated with higher engraftment intensity, and failure to achieve clinical remission was associated with shorter engraftment latency. In the extended group of 68 samples, white blood count was associated with higher engraftment ability, and the presence of a complex karyotype was associated with higher engraftment intensity. Association with patient overall survival was seen only for engraftment intensity.ConclusionsThe engraftment of AML was influenced by mutation-interactions and other AML characteristics, rather than by single mutated genes, and engraftment intensity best reflected clinical penetrance of AML.

Cor Triatriatum and Unusual Pulmonary Venous Drainage

We illustrate the case of a 2-year-old girl presenting with failure to thrive, dyspnea, and systolic murmur. Echocardiography established the diagnosis of cor triatriatum sinistrum with moderate obstruction (arrow) between the upper and lower parts of the divided left atrium with a mean Doppler gradient of 5 mmHg (Figure 1; red line = membrane, yellow line = interatrial septum). A partial anomalous pulmonary venous drainage of the left upper pulmonary vein to the innominate vein via a dilated vertical vein was also observed. Due to unclear pulmonary venous drainage of all pulmonary veins, the patient underwent coronary computed tomography angiography examination, which confirmed cor triatriatum sinistrum and pulmonary venous drainage of the left upper pulmonary vein to the dilated innominate vein. A surprising finding was the presence of a connection (*) between the anomalous drained left upper pulmonary vein and the left atrium (Figure 2). The patient underwent surgical correction (membrane excision and ligation of the vertical vein). Cor triatriatum sinistrum is an uncommon congenital cardiac anomaly accounting for 0.1% of all congenital cardiac defects, in which the left atrium is divided by an abnormal septum. The anomaly may be associated with other congenital cardiac lesions in up to 50% of affected individuals, such as tetralogy of Fallot, ventricular septal defects, and pulmonary anomalous venous drainage. Most patients are asymptomatic and the clinical manifestation are proportional to the degree of obstruction to pulmonary flow through the membrane, depending on the size of the fenestration. Rev Esp Cardiol. 2018;71(5):391

Optimization of Dissolution Compartments in a Biorelevant Dissolution Apparatus Golem v2, Supported by Multivariate Analysis

Biorelevant dissolution instruments represent an important tool for pharmaceutical research and development. These instruments are designed to simulate the dissolution of drug formulations in conditions most closely mimicking the gastrointestinal tract. In this work, we focused on the optimization of dissolution compartments/vessels for an updated version of the biorelevant dissolution apparatus—Golem v2. We designed eight compartments of uniform size but different inner geometry. The dissolution performance of the compartments was tested using immediate release caffeine tablets and evaluated by standard statistical methods and principal component analysis. Based on two phases of dissolution testing (using 250 and 100 mL of dissolution medium), we selected two compartment types yielding the highest measurement reproducibility. We also confirmed a statistically ssignificant effect of agitation rate and dissolution volume on the extent of drug dissolved and measurement reproducibility.

New Drugs in the Treatment of Acute Myeloid Leukemia in the Elderly

BACKGROUND At the time of diagnosis, most patients with acute myeloid leukemia are older than 65 years of age. Treatment of this group of patients is challenging because they become less tolerant to aggressive chemotherapy with increasing age. Less than one-third of elderly patients are considered eligible for intensive treatment; nevertheless, the survival analysis for this population remains poor. Due to numerous comorbidities and an overall deteriorating condition, most elderly patients with acute myeloid leukemia receive only palliative or best supportive care, which are associated with a high mortality rate. New therapeutic approaches are expected to improve the overall survival and quality of life of this group of patients. These promising treatments include cell kinase inhibitors, cytotoxic agents, monoclonal antibodies, and epigenetic therapy including hypomethylating agents and inhibitors of isocitrate dehydrogenase and histone deacetylase. In monotherapy, these new drugs show lower levels of toxicity than those commonly used in chemotherapy; however, they do not lead to a better long-lasting treatment response. To enhance therapeutic efficacy, combinations of the above-mentioned treatments are often used, and, during clinical trials, combinations with standard cytostatics are also common. The promising results of these studies show that even low-toxicity therapies can lead to a better overall treatment response and to longer overall survival. AIM This article provides a brief overview of new drugs that are evaluated for their mechanism of effect, efficacy and toxicity in therapy of patients suffering from acute myeloid leukemia.Key words: acute myeloid leukemia - elderly - FLT3 inhibitors - epigenetic therapy - monoclonal antibodies The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 4. 11. 2016Accepted: 13. 12. 2016.