Methods of Assessment and Clinical Relevance of QT Dynamics

The dependence on heart rate of the QT interval has been investigated for many years and several mathematical formulae have been proposed to describe the QT interval/heart rate (or QT interval/RR interval) relationship. While the most popular is Bazett’s formula, it overcorrects the QT interval at high heart rates and under-corrects it at slow heart rates. This formulae and many others similar ones, do not accurately describe the natural behaviour of the QT interval. The QT interval/RR interval relationship is generally described as QT dynamics. In recent years, several methods of its assessment have been proposed, the most popular of which is linear regression. An increased steepness of the linear QT/RR slope correlates with the risk of arrhythmic death following myocardial infarction. It has also been demonstrated that the QT interval adapts to heart rate changes with a delay (QT hysteresis) and that QT dynamics parameters vary over time. New methods of QT dynamics assessment that take into account these phenomena have been proposed. Using these methods, changes in QT dynamics have been observed in patients with advanced heart failure, and during morning hours in patients with ischemic heart disease and history of cardiac arrest. The assessment of QT dynamics is a new and promising tool for identifying patients at increased risk of arrhythmic events and for studying the effect of drugs on ventricular repolarisation

Methods of Assessment and Clinical Relevance of QT Dynamics

The dependence on heart rate of the QT interval has been investigated for many years and several mathematical formulae have been proposed to describe the QT interval/heart rate (or QT interval/RR interval) relationship. While the most popular is Bazett’s formula, it overcorrects the QT interval at high heart rates and under-corrects it at slow heart rates. This formulae and many others similar ones, do not accurately describe the natural behaviour of the QT interval. The QT interval/RR interval relationship is generally described as QT dynamics. In recent years, several methods of its assessment have been proposed, the most popular of which is linear regression. An increased steepness of the linear QT/RR slope correlates with the risk of arrhythmic death following myocardial infarction. It has also been demonstrated that the QT interval adapts to heart rate changes with a delay (QT hysteresis) and that QT dynamics parameters vary over time. New methods of QT dynamics assessment that take into account these phenomena have been proposed. Using these methods, changes in QT dynamics have been observed in patients with advanced heart failure, and during morning hours in patients with ischemic heart disease and history of cardiac arrest. The assessment of QT dynamics is a new and promising tool for identifying patients at increased risk of arrhythmic events and for studying the effect of drugs on ventricular repolarisation

Long-term Survival in a Child with Malignant Insulinoma After Liver Transplantation

Insulinoma is one of the pancreatic neuroendocrine tumors (PanNET) and is exceptionally rare in children. The tumor leads to severe hypoglycemia caused by excessive insulin release. We report a pediatric patient with malignant insulinoma who underwent liver transplantation (LT) due to liver metastases of the insulinoma. A 13-year-old girl presented with symptoms of hypoglycemia due to hyperinsulinism. On computed tomography (CT), a polycystic lesion in the head of the pancreas and enlarged lymph nodes were revealed. A modified Whipple's operation was performed, and histological examination confirmed PanNET. CT also showed an enlarged liver with numerous metastases. Allogeneic LT was carried out successfully. Positron emission tomography-CT using 68Ga-DOTA-labeled somatostatin analogs (SSAs) at the age of 22 years confirmed complete metabolic remission. The patient currently remains under immunosuppressive and anti-proliferative treatment. Multiple surgical interventions, LT combined with SSAs, and immunosuppressive medication proved effective in this case of metastatic malignant insulinoma

Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation

Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2–10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2–6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

Association between intestinal and antioxidant barriers in children with cancer

Objective: Reactive oxygen species (ROS) play a role in cancerogenesis processing and damage tissues. Furthermore, oncological treatment may impair proper function of the gut barrier. The aim of this study was to measure intestinal permeability in children in clinical remission for solid tumours and to search for a possible relationship between free radicals and the intestinal barrier. No such investigation in children has been reported so far. Research Methods and Procedures: The prospective study consisted of 19 paediatric patients with cancer after completion of chemotherapy. 32 healthy children from the outpatients clinics were recruited for measurement of intestinal permeability and antioxidant barrier as a control group. Intestinal permeability was assessed by measurement of urinary lactulose and mannitol after oral challenge. Antioxidant enzymes: superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in erythrocytes were assessed. Ischemia modified albumin (IMA) concentration was measured in serum. Results: Cancer patients excreted less mannitol and more lactulose versus controls. The ratio of lactulose to mannitol was significantly higher in oncological children vs control (mean 0.188 and 0.0453, respectively, p=0.0006,). Significantly higher IMA level in the oncological group vs control was noted (mean 123.8 and 87.3 U/ml, respectively, p=0.0037). No correlation between intestinal permeability and oxidative stress barrier was found. Conclusions: Our data shows that intestinal barrier is damaged in paediatric cancer patients after chemotherapy. IMA is believed to play a protective role in the defence against tissue damage. No correlation was found between these two barriers

Verteporfin, photofrin II, and merocyanine 540 as PDT photosensitizers against melanoma cells

The efficiency of photodynamic effect (PDE) for Photofrin II (PfII), Verteporfin, and Merocyanine 540 (MC540) was compared against neoplastic cells. Triplet state lifetimes and singlet molecular oxygen quantum yields were correlated with biological effect. PfII triplet lifetime was two times longer than that of Verteporfin, however, its singlet molecular oxygen quantum yield was two times lower in comparison with Verteporfin. High singlet molecular oxygen quantum yield of Verteporfin resulted in high biological efficacy. To achieve 50% mortality of cells four times lower light dose and five times lower concentration of Verteporfin were applied in comparison with PfII. The same level of cell damage was reached using 10 times higher light dose and two times higher concentration of MC540 in comparison with PfII. Our results confirm that singlet molecular oxygen based mechanism, prevalent for Verteporfin and PfII, was highly effective against melanoma cells. Verteporfin can be used at small doses with high cellular damage efficiency