Motion‐compensated b‐tensor encoding for in vivo cardiac diffusion‐weighted imaging

Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.     

Screening for antibacterial activity in 72 species of wood-colonizing fungi by the Vibrio fisheri bioluminescence method

Resistance of pathogenic bacteria to antibiotics leads scientists to discover new antibacterial drugs. Ninety samples of wood-colonizing fungi were cultivated on agar plates, and their extracts tested for antibacterial activity using the Vibrio fischeri bioluminescence test. Two fungi species, Serpula lacrymans and Nectria vilior, were found to be a potential new source of thermostable antibiotics. Vibrio fischeri bioluminescence test was found to be a useful method for antibacterial activity screening from the samples of natural origin.     

Genotyping of spotted tick fever rickettsiae, detected in Russia and Kazakhstan

R. slovaca was first detected in the ticks D. marginatus gathered in the Stavropol Territory and the Voronezh Region (European Russia). The recently discovered rickettsial genotype DnS14 was first found in the ticks D. silvarum from Buryatia and D. niveus from the Karaganda Region (Central Kazakhstan). The rickettsial genotype RpA4 was most common in the ticks of the genus Dermacentor in Russia and Central Kazakhstan. An analysis of the spread of rickettsias of the STF group shows their close ecological relation to definite types of Ixodes. The rickettsias R. slovaca and RpA4 co-exist in the ticks D. marginatus and D. reticulatus (the western part of a Dermacentor area in Eurasia) and DnS14 and R. sibirica do in D. nuttalli and D. silvarum (the eastern part of the area). D. marginatus and D. reticulatus in the areas characterized by the most specific saturation of a Dermacentor area (the south of West Siberia) are carriers and reservoir of R. sibirica. The rickettsial genotype DnS28 may be now considered to be environmentally associated with one species of ticks--D. nuttalli. At least 6 genotypes of STF rickettsias--R. sibirica, R. astrahan fever (R. conorii), R. slovaca, RpA4, DnS14, DnS28--has been currently identified in Russia and Kazakhstan.     

A lethal course of hypertrophic cardiomyopathy in Noonan syndrome due to a novel germline mutation in the KRAS gene: case study

Noonan syndrome is a relatively common and heterogeneous genetic disorder, including congenital heart defect in more than half of the cases. If the defect is not large, life expectancy is normal. Here we report on a case of an infant with Noonan syndrome and rapidly progressive hypertrophic cardiomyopathy with lethal outcome, in whom we identified a novel mutation in the KRAS gene. This heterozygous unclassified missense variant in exon 3: c.179G>T (p.Gly60Val) might be associated with a lethal form of Noonan syndrome. The malignant clinical course of the disease and the lethal outcome in an infant only a few months old might be connected to RAS-mitogen-activated protein kinase pathway hyperactivation, consequently promoting cell growth and proliferation, leading to rapidly progressive hypertrophic cardiomyopathy. Further biochemical and functional studies are needed to confirm this hypothesis.Noonan syndrome (NS; http://www.omim.org/entry/163950?search=163950&highlight=163950) is a relatively common genetic disorder with an incidence of 1 per 1000-2500 live births (1). Clinically it is a very heterogeneous disorder, predominantly characterized by dysmorphic facial features, congenital heart defect (CHD), post-natal short stature, webbed neck, chest deformity, cryptorchidism in men, lymphatic dysplasia, variable bleeding disorders, and intellectual disability. CHD is present in 50 to 80% of affected individuals and it is also very heterogeneous (2). Most commonly found are pulmonary valve stenosis with or without dysplastic pulmonary valve and hypertrophic cardiomyopathy. Providing the CHD is not large, life expectancy is in the normal range (3). NS and CHD are regularly connected with germline KRAS mutations. We describe a patient with NS and rapidly progressive hypertrophic cardiomyopathy with lethal outcome, in whom we identified a novel mutation in the KRAS gene.     

Arteriosclerosis of the right gastro-omental artery]

The right gastroepiploic artery is most frequently used for direct myocardial revascularization. In this connection, its histological study was performed to reveal the atherosclerosis incidence in persons from different age groups who had apparent signs of coronary atherosclerosis. Twenty one arteries taken from adult cadavers at the age of 35-85 years were examined. The arteries with normal were 28.6%, those with Degree I alterations were 52.4%, those with Degree II alterations were 19%. Degrees III and IV alterations were not detected. Morphological studies indicated that hemodynamically significant right gastroepiploic artery lesions were found in 19% of cases, mainly in subjects above 60 years. The artery may be used in coronary surgery as a shunt with a good prognosis of its performance.     

Comparative study of dimephosphon and xidiphone efficacy in steroid-induced osteoporosis in rats

The efficacy of dimephosphon in comparison with xydiphone was studied in rats with an osteoporosis model induced by prednisolone administration at a daily dose of 50 mg/kg over a period of 14 days. The prednisolone treatment led to an increase in the content of oxyproline (a marker of bone resorption), calcium, and inorganic phosphates in the urine. Dimephosphon (monophosphate) decreased the levels of oxyproline, calcium, and inorganic phosphate in the urine. Xydiphone (biphosphonate) equally reduced the oxyproline excretion and the calcium level in urine, while rather insignificantly affecting the phosphaturia. Dimephosphon normalized the blood calcium level, while xydiphone decreased this parameter. An additional advantage of dimephosphon over xydiphone was manifested by normalization of the body weight of test rats and the total blood protein level.