Rapid, non-invasive, in vivo measurement of tissue mechanical properties using gravitational loading and a nonlinear virtual fields method.

Measuring the mechanical properties of soft tissues in vivo is important in biomechanics and for diagnosis and staging of diseases, but challenging because it is difficult to control the boundary conditions. We present a novel, non-invasive method for measuring tissue properties using gravitational loading. MRI images of an organ in different positions are registered to measure tissue displacements due to gravitational forces in different positions. Considering equilibrium between stresses and gravity, we established a nonlinear virtual fields method to identify the tissue properties. The method was applied to the human brain as a proof of concept, using an Ogden model. Sensitivity analysis showed that the bulk modulus could be identified accurately while the shear modulus was identified with greater uncertainty; the strains were too small to identify the strain stiffening exponent. The measured properties agreed well with published in vitro data. The technique offers very promising perspectives, allowing the non-invasive measurement of otherwise inaccessible tissues and providing new information such as the bulk modulus under static loading, which has never previously been measured in vivo.

Atmospheric pollution, soil nutrients and climate effects on Mucoromycota arbuscular mycorrhizal fungi.

Fine root endophyte mycorrhizal fungi in the Endogonales (Mucoromycota arbuscular mycorrhizal fungi, M-AMF) are now recognized as at least as important globally as Glomeromycota AMF (G-AMF), yet little is known about the environmental factors which influence M-AMF diversity and colonization, partly because they typically only co-colonize plants with G-AMF. Wild populations of Lycopodiella inundata predominantly form mycorrhizas with M-AMF and therefore allow focussed study of M-AMF environmental drivers. Using microscopic examination and DNA sequencing we measured M-AMF colonization and diversity over three consecutive seasons and modelled interactions between these response variables and environmental data. Significant relationships were found between M-AMF colonization and soil S, P, C:N ratio, electrical conductivity, and the previously overlooked micronutrient Mn. Estimated N deposition was negatively related to M-AMF colonization. Thirty-nine Endogonales Operational Taxonomic Units (OTUs) were identified in L. inundata roots, a greater diversity than previously recognized in this plant. Endogonales OTU richness correlated negatively with soil C:N while community composition was mostly influenced by soil P. This study provides first evidence that M-AMF have distinct ecological preferences in response to edaphic variables also related to air pollution. Future studies require site-level atmospheric pollution monitoring to guide critical load policy for mycorrhizal fungi in heathlands and grasslands.

[MANAGEMENT ASPECTS OF PROFESSIONAL SAFETY OF MEDICAL PERSONNEL IN BUDGETARY HEALTH OF RUSSIA].

The study examines the issues of assessing the impact on occupational safety of public health workers of psycho-emotional factors associated with the provision of medical services and the socio-economic and industrial conditions of their work. As the analysis conducted by the authors on the basis of foreign sources showed, this problem is characteristic not only for Russia, but also for most medical institutions in other countries. It should be noted that these problems were especially aggravated during the coronavirus pandemic, when it was necessary to work in conditions of increased risk of infection, in excess of the established time norm, etc. Moreover, the tools to overcome professional burnout and improve occupational safety are providing medical institutions with the required personnel in sufficient quantities to solve the tasks, providing diagnostic and medical equipment, as well as protective equipment. It is very important that evidence-based labor standards are implemented, as they have not been reviewed in most cases since Soviet times. At the same time, ensuring decent work indicators, especially wages, is very important.

Tension-free hernioplasty: technical remarks and personal experience.

The authors report their experience with 463 tension free hernioplasty procedures for inguinal and femoral hernias. The surgical technique included the insertion of both a polypropylene plug and a polypropylene mesh, and was carried out mostly in local anesthesia (84.2%) using bupivacaine 0.25% for ileoinguinal and ileohypogastric blockage and mepivacaine 0.5% for local infiltration. There was no major intraoperative complication; local postoperative complications were rare (10%) and easily managed; postoperative pain was frequently observed (66%), though mild and transient; resumption of working activity occurred within a month in 96.6% of cases; there were only 3 post-operative recurrences (respectively, at 1, 6 and 12 months). The authors conclude that the tension free hernioplasty is a simple, rapid, low-cost and effective technique, easily performed under local anesthesia.

The use of the hCG stimulation test in the endocrine evaluation of cryptorchidism.

OBJECTIVE: To review retrospectively the value of the human chorionic gonadotrophin (hCG) test in the evaluation of prepubertal boys with bilateral impalpable testes. SUBJECTS AND METHODS: The study comprised 31 boys investigated between 1974 and 1990 at the Hospital for Sick Children, London. All boys had an hCG test consisting of three intramuscular injections of hCG on successive days at a daily dose dependent on their age (< 1 year old, 500 units; 1-10 years, 1000 units; > 10 years, 1500 units). Blood samples were taken before the first dose and 24 h after the last dose and the level of plasma testosterone assessed and expressed as a pre/post ratio. RESULTS: Eight boys had no response to hCG, due to anorchia. One boy had no response to hCG but had bilateral atrophic intra-abdominal testes. Twenty-two boys responded to hCG and had testes whose size was related to the degree of testosterone elevation after this stimulatory test. The hCG test therefore had a positive predictive value of 89% and a negative predictive value of 100%. There was a quantitative difference in testosterone response between 14 boys who had bilateral intra-abdominal testes of 'normal' volume (median pre/post ratio, 11.4) and nine boys who had an otherwise reduced volume of testes (dysplastic or unilateral intra-abdominal) (median pre/post ratio of 4; P = 0.02). CONCLUSION: The hCG test is a valid indicator of the presence of functioning testicular tissue. It is predictive of anorchia and a good response to hCG suggests the presence of testes sufficiently large for orchidopexy.

Endoscopic reappraisal of the morphology of congenital obstruction of the posterior urethra.

Congenital obstruction of the posterior urethra was first systematically classified by Young in 1919. Since then, no-one has seriously challenged the presence of both Type I and Type III "valves", although the presence of Type II lesions has often been disputed. A review of Young's papers and more recent anatomical studies, together with endoscopic findings in our own patients, indicates that most congenital posterior urethral obstructions are anatomically similar. Consequently, Young's classification now seems redundant.