Застосування рівняння Віганда–Снайдера до термодинамічної інтерпретації високоеластичної деформації гладеньких м'язів шлунка

Iз застосуванням рiвняння Вiганда–Снайдера здiйснено термодинамiчний аналiз високоеластичної деформацiї (Δl) кiльцевих гладеньких м’язiв антрального вiддiлу шлунка щурiв. Показано, що малi (Δl/l0 ≈ 20%) розтягування гладеньком’язових смужок шлунка щурiв (дiапазон температур 22–48 °С) не супроводжуються змiнами у впорядкованостi тензометричної системи (ΔS = 0). Такий самий феномен маємо i у випадку значних розтягувань (Δl/l0 ≈ 50%), але у бiльш вузькому дiапазонi температур: понад 30 °С i менше 40 °С. При великих розтягуваннях гладеньком’язових смужок шлунка (Δl/l0 ≈ 50%) як при вiдносно низьких (22–30 °С), так i при вiдносно високих (понад 37 °С) температурах мають мiсце iстотнi структурнi змiни в тензометричнiй системi. За цих умов спостерiгається iнверсiя знаку ентропiйних ефектiв: ΔS > 0 при T 37 °С. Обговорюється зв’язок мiж виявленими термодинамiчними ефектами i фiзiологiчними механiзмами регуляцiї функцiонування травного тракту.Применение уравнения Виганда–Снайдера проведен термодинамический анализ высокоэластичной деформации кольцевых гладких мышц антрального отдела желудка крыс. Показано, что малые (Δl/l0 ≈ 20%) растягивания гладкомышечных полосок желудка крыс (диапазон температур 22–48 °С) не сопровождаются изменениями в упорядоченности тензометрической системы (ΔS = 0). Такой же феномен наблюдается и при значительных растягиваниях (Δl/l0 ≈ 50%), но в более узком диапазоне температур: выше 30 °С и ниже 40 °С. При больших растяжениях гладкомышечных полосок желудка (Δl/l0 ≈ 50%) как при относительно низких (22–30 °С), так и при относительно высоких (выше 37 °С) температурах имеют место существенные структурные изменения в тензометрической системе. В этих условиях наблюдается инверсия знака энтропийных эффектов: ΔS > 0 при T 37 °С. Обсуждается связь между выявленными термодинамическими эффектами и физиологическими механизмами регуляции функционирования пищеварительного тракта.With using the Wiegand–Snyder equation, the thermodynamic analysis of a viscoelastic deformation of circular smooth muscle strips of rat’s stomach (antral part) is performed. It is shown that a small (Δl/l0 ≈ 20%) stretch of rat stomach smooth muscle strips (temperature range 22–48 °С) is not accompanied by changes in the ordering of the tensometric system (ΔS = 0). The same phenomenon is observed with a considerable stretching (Δl/l0 ≈ 50%), but in a narrower tempera- ture range: above 30 °C and below 40 °C. For large strains, gastric smooth muscle strips (Δl/l0 ≈ 50%) at relatively low (22–30 °C) and at relatively high (above 37 °C) temperatures undergo substantial structural changes in the ordering of the tensometric system. Under these conditions, there is the inversion of the sign of entropy effects: ΔS > 0 at temperatures below 31 °C and ΔS < 0 at temperatures above 37 °C. The relation between the identified thermodynamic effects and the physiological mechanisms of regulation of the functioning of the digestive tract is discussed

Еще об одном русском ключевом концепте

В статье показаны основные составляющие русского концепта "разлука", который, судя по встречаемости имени "разлука" в текстах русской культуры, является одним из ключевых. Показывается, что этот концепт связан с другими ключевыми русскими концептами - "дом", "свобода". Основная мысль статьи - содержание этого концепта подверглось значительным социокультурным модификациям.У статті показано основні складові російского концепта "розлука", який, судячи по вживанню імені "розлука" в текстах російскої культури, є одним з ключовіх. Показується, що цей концепт пов'язаний з іншими ключовіми російскими концептами " будинок", "свобода". Основна думка статті - зміст цього концепта зазнав значних социокультурних модифікацій.In article basic components of Russian concept "separation" ("parting") are analysed. An author considers this concept to be one of key Russian concepts according to usage of word "razluka" in Russian culture texts. Interdependence of concept "separation" and other Russian key concepts such as "home", "freedom" is shown. A main author's idea is that value of this concept was being a subject of considerable sociocultural modifications

Kinetics of acute hepatitis B virus infection in humans

Using patient data from a unique single source outbreak of hepatitis B virus (HBV) infection, we have characterized the kinetics of acute HBV infection by monitoring viral turnover in the serum during the late incubation and clinical phases of the disease in humans. HBV replicates rapidly with minimally estimated doubling times ranging between 2.2 and 5.8 d (mean 3.7 ± 1.5 d). After a peak viral load in serum of nearly 1010 HBV DNA copies/ml is attained, clearance of HBV DNA follows a two or three phase decay pattern with an initial rapid decline characterized by mean half-life (t1/2) of 3.7 ± 1.2 d, similar to the t1/2 observed in the noncytolytic clearance of covalently closed circular DNA for other hepadnaviruses. The final phase of virion clearance occurs at a variable rate (t1/2 of 4.8 to 284 d) and may relate to the rate of loss of infected hepatocytes. Free virus has a mean t1/2 of at most 1.2 ± 0.6 d. We estimate a peak HBV production rate of at least 1013 virions/day and a maximum production rate of an infected hepatocyte of 200–1,000 virions/day, on average. At this peak rate of virion production we estimate that every possible single and most double mutations would be created each day

Autoimmune pancreatitis/IgG4-associated cholangitis and primary sclerosing cholangitis – Overlapping or separate diseases?

Autoimmune pancreatitis is a recently described fibroinflammatory disease which is characterised by raised serum levels of IgG4 (in >70% of cases), and an IgG4-positive lymphoplasmacytic tissue infiltrate. A favourable and rapid clinical response to oral steroid therapy is often seen. Biliary involvement is common, and the term IgG4-associated cholangitis has recently been coined. The cholangiographic appearances of IgG4-associated cholangitis and primary sclerosing cholangitis can be difficult to differentiate. Moreover, raised levels of serum IgG4 have been recently found in 9% of patients with primary sclerosing cholangitis (a much higher frequency than for other gastrointestinal diseases), and those with raised levels appear to progress more rapidly to liver failure. Here we review the similarities and differences between the biliary disease in autoimmune pancreatitis and primary sclerosing cholangitis, and address the issue of disease overlap. Improvements in understanding the relationship between these conditions might lead to an enhanced understanding of the aetiopathogenesis, and improved treatment of both conditions

Reef response to sea-level and environmental changes during the last deglaciation: Integrated Ocean Drilling Program Expedition 310, Tahiti Sea Level

The last deglaciation is characterized by a rapid sea-level rise and coeval abrupt environmental changes. The Barbados coral reef record suggests that this period has been punctuated by two brief intervals of accelerated melting (meltwater pulses, MWP), occurring at 14.08-13.61 ka and 11.4-11.1 ka (calendar years before present), that are superimposed on a smooth and continuous rise of sea level. Although their timing, magnitude, and even existence have been debated, those catastrophic sea-level rises are thought to have induced distinct reef drowning events. The reef response to sea-level and environmental changes during the last deglacial sea-level rise at Tahiti is reconstructed based on a chronological, sedimentological, and paleobiological study of cores drilled through the relict reef features on the modern forereef slopes during the Integrated Ocean Drilling Program Expedition 310, complemented by results on previous cores drilled through the Papeete reef. Reefs accreted continuously between 16 and 10 ka, mostly through aggradational processes, at growth rates averaging 10 mm yr-1. No cessation of reef growth, even temporary, has been evidenced during this period at Tahiti. Changes in the composition of coralgal assemblages coincide with abrupt variations in reef growth rates and characterize the response of the upward-growing reef pile to nonmonotonous sea-level rise and coeval environmental changes. The sea-level jump during MWP 1A, 16 ± 2 m of magnitude in ~350 yr, induced the retrogradation of shallow-water coral assemblages, gradual deepening, and incipient reef drowning. The Tahiti reef record does not support the occurrence of an abrupt reef drowning event coinciding with a sea-level pulse of ~15 m, and implies an apparent rise of 40 mm yr-1 during the time interval corresponding to MWP 1B at Barbados. © 2012 Geological Society of America