Electropermeabilization of endocytotic vesicles in B16 F1 mouse melanoma cells

It has been reported previously that electric pulses of sufficiently high voltage and short duration can permeabilize the membranes of various organelles inside living cells. In this article, we describe electropermeabilization of endocytotic vesicles in B16 F1 mouse melanoma cells. The cells were exposed to short, high-voltage electric pulses (from 1 to 20 pulses, 60 ns, 50 kV/cm, repetition frequency 1 kHz). We observed that 10 and 20 such pulses induced permeabilization of membranes of endocytotic vesicles, detected by release of lucifer yellow from the vesicles into the cytosol. Simultaneously, we detected uptake of propidium iodide through plasma membrane in the same cells. With higher number of pulses permeabilization of the membranes of endocytotic vesicles by pulses of given parameters is accompanied by permeabilization of plasma membrane. However, with lower number of pulses only permeabilization of the plasma membrane was detected.     

Overexpression of vascular endothelial growth factor-B in mouse heart alters cardiac lipid metabolism and induces myocardial hypertrophy

Vascular endothelial growth factor (VEGF)-B is poorly angiogenic but prominently expressed in metabolically highly active tissues, including the heart. We produced mice expressing a cardiac-specific VEGF-B transgene via the alpha-myosin heavy chain promoter. Surprisingly, the hearts of the VEGF-B transgenic mice showed concentric cardiac hypertrophy without significant changes in heart function. The cardiac hypertrophy was attributable to an increased size of the cardiomyocytes. Blood capillary size was increased, whereas the number of blood vessels per cell nucleus remained unchanged. Despite the cardiac hypertrophy, the transgenic mice had lower heart rate and blood pressure than their littermates, and they responded similarly to angiotensin II-induced hypertension, confirming that the hypertrophy does not compromise heart function. Interestingly, the isolated transgenic hearts had less cardiomyocyte damage after ischemia. Significantly increased ceramide and decreased triglyceride levels were found in the transgenic hearts. This was associated with structural changes and eventual lysis of mitochondria, resulting in accumulation of intracellular vacuoles in cardiomyocytes and increased death of the transgenic mice, apparently because of mitochondrial lipotoxicity in the heart. These results suggest that VEGF-B regulates lipid metabolism, an unexpected function for an angiogenic growth factor.     

Effect of selective and nonselective β-blockers on resting energy production rate and total body substrate utilization in chronic heart failure

Background: In chronic heart failure (CHF) β-blockers reduce myocardial oxygen consumption and improve myocardial efficiency by shifting myocardial substrate utilization from increased free fatty acid oxidation to increased glucose oxidation. The effect of selective and nonselective β-blockers on total body resting energy production rate (EPR) and substrate utilization is not known. Methods: Twenty-six noncachectic patients with moderately severe heart failure (New York Heart Association class II or III, left ventricular ejection fraction < 0.40) were treated with carvedilol (37.5 ± 13.5 mg/12 h) or bisoprolol (5.4 ± 3.0 mg/d) for 6 months. Indirect calorimetry was performed before and after 6 months of treatment. Results: Resting EPR was decreased in carvedilol (5.021 ± 0.803 to 4.552 ± 0.615 kJ/min, P < .001) and bisoprolol group (5.230 ± 0.828 to 4.978 ± 0.640 kJ/min, P < .05; nonsignificant difference between groups). Lipid oxidation rate decreased in carvedilol and remained unchanged in bisoprolol group (2.4 ± 1.4 to 1.5 ± 0.9 mg m²/kg min versus 2.7 ± 1.1 to 2.5 ± 1.1 mg m²/kg min, P < .05). Glucose oxidation rate was increased only in carvedilol (2.6 ± 1.4 to 4.4 ± 1.6 mg m²/kg min, P < .05), but did not change in bisoprolol group. Conclusions: Both selective and nonselective β-blockers reduce total body resting EPR in noncachectic CHF patients. Carvedilol compared to bisoprolol shifts total body substrate utilization from lipid to glucose oxidation.     

Role of sex in post-transplant diabetes mellitus development: Are men and women equal?

Introduction

Sex differences are defined as biology-linked differences between women and men that occur through the sex chromosomes and their effects on organ systems.

Light transmittance and polymerization kinetics of amorphous calcium phosphate composites

Clinical Oral Investigations - This study investigated light transmittance and polymerization kinetics of experimental remineralizing composite materials based on amorphous calcium phosphate (ACP),...     

The Waist Width of Skis Influences the Kinematics of the Knee Joint in Alpine Skiing

Recently alpine skis with a wider waist width, which medially shifts the contact between the ski edge and the snow while turning, have appeared on the market. The aim of this study was to determine the knee joint kinematics during turning while using skis of different waist widths (65mm, 88mm, 110mm). Six highly skilled skiers performed ten turns on a predefined course (similar to a giant slalom course). The relation of femur and tibia in the sagital, frontal and coronal planes was captured by using an inertial motion capture suit, and Global Navigation Satellite System was used to determine the skiers’ trajectories. With respect of the outer ski the knee joint flexion, internal rotation and abduction significantly decreased with the increase of the ski waist width for the greatest part of the ski turn. The greatest abduction with the narrow ski and the greatest external rotation (lowest internal rotation) with the wide ski are probably the reflection of two different strategies of coping the biomechanical requirements in the ski turn. These changes in knee kinematics were most probably due to an active adaptation of the skier to the changed biomechanical conditions using wider skis. The results indicated that using skis with large waist widths on hard, frozen surfaces could bring the knee joint unfavorably closer to the end of the range of motion in transversal and frontal planes as well as potentially increasing the risk of degenerative knee injuries.

Key points

• The change in the skis’ waist width caused a change in the knee joint movement strategies, which had a tendency to adapt the skier to different biomechanical conditions.
• The use of wider skis or, in particular, skis with a large waist width, on a hard or frozen surface, could unfavourably bring the knee joint closer to the end of range of motion in transversal and frontal planes as well as may potentially increase the risk of degenerative knee injuries.
• The overall results of the abduction and internal rotation in respect to turn radii and ground reaction forces indicated that the knee joint movements are likely one of the key points in alpine skiing techniques. However, the skiing equipment used can still significantly influence the movement strategy.

Key words: Abduction, inertial sensor, rotation, ski turn, three-dimensional joint movements     

A case of interstitial pneumonitis in a patient with ulcerative colitis treated with azathioprine

The early hypersensitivity reaction and late bone marrow depression are well-known side-effects of azathioprine, whereas interstitial pneumonia is a rare complication. A 40-year old male patient had been treated with azathioprine in consequence of extensive ulcerative colitis for 10 years. He then complained of 7 d of fever, cough and catarrhal signs, without symptoms of active colitis. Opportunistic infections were ruled out. The chest X-ray, CT and lung biopsy demonstrated the presence of interstitial inflammation. Azathioprine therapy was discontinued as a potential source of the pulmonary infiltrate. In response to steroid therapy, and intensive care, the pulmonary infiltrate gradually decreased within 4 wk. Three months later, his ulcerative colitis relapsed, and ileo-anal pouch surgery was performed. In cases of atypical pneumonia, without a proven infection, azathioprine-associated interstitial pneumonitis may be present, which heals after withdrawal of the drug.     

The uncertainty in burn prediction as a result of variable skin parameters: An experimental evaluation of burn-protective outfits

The reliable prediction of burns, resulting from exposure to elevated levels of heat, received early interest in physiology and later on in various branches of applied research and engineering. In this paper we address the problem of estimating the extent of skin burns in the context of a quantitative assessment of protective garments from the statistical point of view. We rely on the experimental platform built around the thermal mannequin equipped with an array of thermal sensors. The dressed mannequin is first exposed to the flash fire, in order to determine the incident heat flux on the mannequin’s surface. This information is then used in a heat-transfer model of the skin, the result of which is an estimate of the degree of injury that would occur to a human exposed to the same flame conditions. The methods used so far, employed a deterministic skin model defined with the nominal thermal and geometrical parameters. However, skin properties differ from human to human and from one location on the body to another; this results in different configurations of the areas affected by injuries. In this paper we apply a Monte-Carlo approach to estimate the dispersion of the burns over a broad population of humans. The results obtained from experimental data records indicate that the variations in the dermis are the most decisive for increased dispersions at the estimated second- and third-degree burn areas.