Acid-adaptive mechanisms of gastric Helicobacter

1998 ◽  
pp. 133-147
Author(s):  
D. Scott ◽  
D. Weeks ◽  
M. Rektorschek ◽  
G. Sachs ◽  
K. Melchers
Keyword(s):  
2007 ◽  
Vol 43 ◽  
pp. 105-120 ◽  
Author(s):  
Michael L. Paffett ◽  
Benjimen R. Walker

Several molecular and cellular adaptive mechanisms to hypoxia exist within the vasculature. Many of these processes involve oxygen sensing which is transduced into mediators of vasoconstriction in the pulmonary circulation and vasodilation in the systemic circulation. A variety of oxygen-responsive pathways, such as HIF (hypoxia-inducible factor)-1 and HOs (haem oxygenases), contribute to the overall adaptive process during hypoxia and are currently an area of intense research. Generation of ROS (reactive oxygen species) may also differentially regulate vascular tone in these circulations. Potential candidates underlying the divergent responses between the systemic and pulmonary circulations may include Nox (NADPH oxidase)-derived ROS and mitochondrial-derived ROS. In addition to alterations in ROS production governing vascular tone in the hypoxic setting, other vascular adaptations are likely to be involved. HPV (hypoxic pulmonary vasoconstriction) and CH (chronic hypoxia)-induced alterations in cellular proliferation, ionic conductances and changes in the contractile apparatus sensitivity to calcium, all occur as adaptive processes within the vasculature.


2018 ◽  
Vol 319 (10) ◽  
pp. 15-19 ◽  
Author(s):  
A.V. Miftakhutdinov ◽  
◽  
E.M. Amineva ◽  
N.M. Kolobkova ◽  
D.M. Kolobkov ◽  
...  

Author(s):  
А.Б. Салтыков ◽  
С.В. Грачев

Редукционистский подход в медицине рассматривает живые системы в качестве закрытых (замкнутых) образований, функции которых полностью детерминированы свойствами соответствующих материальных компонентов. Каждое нарушение функции объясняется предшествующими изменениями структур, реализующих эту функцию. Из этого следует, что любая патология структурно-функциональна по своей сути, а понятие «функциональные заболевания» - принципиально ошибочно из-за искажения причинно-следственных отношений. По мере прогресса медицины ожидается открытие собственно первичных структурных маркеров «функциональных» заболеваний, что будет иметь решающее значение для их ранней диагностики и патогенетического лечения (ориентированного прежде всего, на устранение первичного звена расстройств). Вместе с тем, в медицине существует более общий холистический (функционально ориентированный) подход, формирующий иной стереотип клинического мышления. В этих рамках любая патология объясняется недостаточностью адаптивных функций организма в изменившихся условиях существования. Обычно сложный характер функциональных взаимодействий делает невозможным их описание на основе текущих характеристик материальных компонентов системы, особенно при воздействии на организм внешних патогенных факторов. Именно внешние воздействия способны инициировать первичный дефицит адаптивных механизмов с заведомо вторичными структурными изменениями, что позволяет перестать рассматривать «функциональные болезни» как принципиально ошибочное понятие. Первичный дефицит функций наиболее нагляден при информационной патологии, идеальная природа которой не сводится к соответствующим материальным носителям. Все это ставит под сомнение возможность обнаружения собственно первичных структурных маркеров некоторых заболеваний, особенно если в их основе лежит информационная патология (невроз, нервная анорексия, психическая аменорея, морская болезнь, некоторые формы фантомных болей и др.). Reductionist approach in medicine considers living systems as closed (closed) formations whose functions are completely determined by the properties of the corresponding material components. Each disturbance of the function is explained by previous changes in the structures that realize this function. From this it follows that any pathology is structurally functional in its essence, and the concept of «functional diseases» is fundamentally erroneous because of the distortion of cause-effect relationships. As medicine progresses, the actual primary structural markers of «functional» diseases are expected to be discovered, which will be crucial for their early diagnosis and pathogenetic treatment (primarily aimed at eliminating the primary link of disorders). At the same time, in medicine there is a more general holistic (functionally oriented) approach, forming a different stereotype of clinical thinking. Within this framework, any pathology is due to the lack of adaptive functions of the organism in the changed conditions of existence. Usually the complex nature of functional interactions makes it impossible to describe them on the basis of the current characteristics of the material components of the system, especially when external pathogenic factors influence the organism. It is external actions that can initiate a primary deficit of adaptive mechanisms with known secondary structural changes, which allows us to stop treating «functional diseases» as a fundamentally wrong concept. The primary deficit of functions is most evident in information pathology, the ideal nature of which is not reduced to the corresponding material carriers. All this calls into question the possibility of detecting the primary structural markers of certain diseases, especially if they are based on information pathology (neurosis, anorexia nervosa, mental amenorrhea, seasickness, some forms of phantom pains, etc.).


Author(s):  
U. Khompodoeva ◽  
R. Ivanov

The results of researches on the peculiarities of metabolism in the body of horses of Yakut breed in the winter and spring periods under the environments of Central Yakutia have been presented in the article. Physiological experiments on the digestibility of the main nutrients of the feed have been carried out in the winter (February) and spring (April) periods under the environments of the physiological yard in the Yakutsk Scientific and Research Institute of Agriculture named after M. G. Safronov with using the classical method. Five mares and five geldings of Yakut breed have been selected for researches. The average live weight of mares was 378–410 kg, geldings 394–403 kg. The experimental animals had average fatness. It has been found a higher intake of energy and the main nutrients of hay as a mono feed in winter compared to the spring period. At the same time pregnant mares in winter have been consumed 103,8±3,12 MJ of metabolic energy per head/day, which was 27,3 % significantly higher than in the spring period – 75,4±2,18 MJ (P ≥ 0,999). Geldings have been consumed in the experiment 67,70±2,85 MJ, which was by 43,7 % higher than in the spring period – 38,05 ± 4,40 MJ of metabolic energy per head/day (P ≥ 0,999). Experimental animals have been housed in stalls; there was no energy expenditure for movement, so the amount of energy consumed in winter indicates the production of heat in the animal’s body. Pregnant mares per 100 kg of live weight have consumed 31,5±4,11 MJ of metabolic energy or 33,3 % more than in the spring period – 21,0±1,98 MJ; geldings have consumed 27,69±1,12, which was 41,78 % significantly higher than in the spring – 16,12 ± 0,75 MJ (P ≥ 0,999). The high intake of metabolic energy into the body of Yakut horses in winter is explained by the manifestation of adaptive mechanisms that affect the effective metabolism for survival, adapted to frequent changes in weather conditions and sharp temperature changes. The established differences in the biochemical parameters of blood serum of horses of Yakut breed are associated with changes in the consumption and digestibility of basic nutrients and energy, depending on the ambient temperature.


2015 ◽  
Vol 22 (2) ◽  
pp. 149-163 ◽  
Author(s):  
Maria Macedo ◽  
Caio de Oliveira ◽  
Poliene Costa ◽  
Elaine Castelhano ◽  
Marcio Silva-Filho

2019 ◽  
Vol 374 (1785) ◽  
pp. 20190277 ◽  
Author(s):  
Edgar T. Walters

Chronic pain is considered maladaptive by clinicians because it provides no apparent protective or recuperative benefits. Similarly, evolutionary speculations have assumed that chronic pain represents maladaptive or evolutionarily neutral dysregulation of acute pain mechanisms. By contrast, the present hypothesis proposes that chronic pain can be driven by mechanisms that evolved to reduce increased vulnerability to attack from predators and aggressive conspecifics, which often target prey showing physical impairment after severe injury. Ongoing pain and anxiety persisting long after severe injury continue to enhance vigilance and behavioural caution, decreasing the heightened vulnerability to attack that results from motor impairment and disfigurement, thereby increasing survival and reproduction (fitness). This hypothesis is supported by evidence of animals surviving and reproducing after traumatic amputations, and by complex specializations that enable primary nociceptors to detect local and systemic signs of injury and inflammation, and to maintain low-frequency discharge that can promote ongoing pain indefinitely. Ongoing activity in nociceptors involves intricate electrophysiological and anatomical specializations, including inducible alterations in the expression of ion channels and receptors that produce persistent hyperexcitability and hypersensitivity to chemical signals of injury. Clinically maladaptive chronic pain may sometimes result from the recruitment of this powerful evolutionary adaptation to severe bodily injury. This article is part of the Theo Murphy meeting issue ‘Evolution of mechanisms and behaviour important for pain’.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Talora L. Martin ◽  
Jordan Murray ◽  
Kiran Garg ◽  
Charles Gallagher ◽  
Aasef G. Shaikh ◽  
...  

AbstractWe evaluated the effects of strabismus repair on fixational eye movements (FEMs) and stereopsis recovery in patients with fusion maldevelopment nystagmus (FMN) and patients without nystagmus. Twenty-one patients with strabismus, twelve with FMN and nine without nystagmus, were tested before and after strabismus repair. Eye-movements were recorded during a gaze-holding task under monocular viewing conditions. Fast (fixational saccades and quick phases of nystagmus) and slow (inter-saccadic drifts and slow phases of nystagmus) FEMs and bivariate contour ellipse area (BCEA) were analyzed in the viewing and non-viewing eye. Strabismus repair improved the angle of strabismus in subjects with and without FMN, however patients without nystagmus were more likely to have improvement in stereoacuity. The fixational saccade amplitudes and intersaccadic drift velocities in both eyes decreased after strabismus repair in subjects without nystagmus. The slow phase velocities were higher in patients with FMN compared to inter-saccadic drifts in patients without nystagmus. There was no change in the BCEA after surgery in either group. In patients without nystagmus, the improvement of the binocular function (stereopsis), as well as decreased fixational saccade amplitude and intersaccadic drift velocity, could be due, at least partially, to central adaptive mechanisms rendered possible by surgical realignment of the eyes. The absence of improvement in patients with FMN post strabismus repair likely suggests the lack of such adaptive mechanisms in patients with early onset infantile strabismus. Assessment of fixation eye movement characteristics can be a useful tool to predict functional improvement post strabismus repair.


PROTOPLASMA ◽  
2021 ◽  
Author(s):  
Cynthia Medwed ◽  
Andreas Holzinger ◽  
Stefanie Hofer ◽  
Anja Hartmann ◽  
Dirk Michalik ◽  
...  

AbstractSingle-celled green algae within the Trebouxiophyceae (Chlorophyta) are typical components of terrestrial habitats, which often exhibit harsh environmental conditions for these microorganisms. This study provides a detailed overview of the ecophysiological, biochemical, and ultrastructural traits of an alga living on tree bark. The alga was isolated from a cypress tree in the Botanical Garden of Innsbruck (Austria) and identified by morphology and molecular phylogeny as Diplosphaera chodatii. Transmission electron microscopy after high-pressure freezing (HPF) showed an excellent preservation of the ultrastructure. The cell wall was bilayered with a smooth inner layer and an outer layer of polysaccharides with a fuzzy hair-like appearance that could possibly act as cell-cell adhesion mechanism and hence as a structural precursor supporting biofilm formation together with the mucilage observed occasionally. The photosynthetic-irradiance curves of D. chodatii indicated low light requirements without photoinhibition at high photon flux densities (1580 μmol photons m−2 s−1) supported by growth rate measurements. D. chodatii showed a high desiccation tolerance, as 85% of its initial value was recovered after controlled desiccation at a relative humidity of ~10%. The alga contained the low molecular weight carbohydrates sucrose and sorbitol, which probably act as protective compounds against desiccation. In addition, a new but chemically not elucidated mycosporine-like amino acid was detected with a molecular mass of 332 g mol−1 and an absorption maximum of 324 nm. The presented data provide various traits which contribute to a better understanding of the adaptive mechanisms of D. chodatii to terrestrial habitats.


2021 ◽  
Vol 35 (3) ◽  
pp. 284-302
Author(s):  
Ilijana Babic ◽  
Dominic Sellers ◽  
Paul L Else ◽  
Jessica Nealon ◽  
Ashleigh L Osborne ◽  
...  

Background: Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist that prevents metabolic side effects of the antipsychotic drugs (APDs) olanzapine and clozapine through unknown mechanisms. Aim: This study aimed to investigate the effect of chronic APD and liraglutide co-treatment on key neural and peripheral metabolic signals, and acute liraglutide co-treatment on clozapine-induced hyperglycaemia. Methods: In study 1, rats were administered olanzapine (2 mg/kg), clozapine (12 mg/kg), liraglutide (0.2 mg/kg), olanzapine + liraglutide co-treatment, clozapine + liraglutide co-treatment or vehicle for six weeks. Feeding efficiency was examined weekly. Examination of brain tissue (dorsal vagal complex (DVC) and mediobasal hypothalamus (MBH)), plasma metabolic hormones and peripheral (liver and kidney) cellular metabolism and oxidative stress was conducted. In study 2, rats were administered a single dose of clozapine (12 mg/kg), liraglutide (0.4 mg/kg), clozapine + liraglutide co-treatment or vehicle. Glucose tolerance and plasma hormone levels were assessed. Results: Liraglutide co-treatment prevented the time-dependent increase in feeding efficiency caused by olanzapine, which plateaued by six weeks. There was no effect of chronic treatment on melanocortinergic, GABAergic, glutamatergic or endocannabionoid markers in the MBH or DVC. Peripheral hormones and cellular metabolic markers were unaltered by chronic APD treatment. Acute liraglutide co-treatment was unable to prevent clozapine-induced hyperglycaemia, but it did alter catecholamine levels. Conclusion: The unexpected lack of change to central and peripheral markers following chronic treatment, despite the presence of weight gain, may reflect adaptive mechanisms. Further studies examining alterations across different time points are required to continue to elucidate the mechanisms underlying the benefits of liraglutide on APD-induced metabolic side effects.


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