Climatic and topographic changes since the Miocene influenced the diversification and biogeography of the tent tortoise (Psammobates tentorius) species complex in Southern Africa

Background: Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotspots in the world, the Succulent Karoo and Cape Floristic Region. The highly diverged P. tentorius represents an excellent model species for exploring biogeographic and radiation patterns of reptiles in Southern Africa. Results: We investigated genetic structure and radiation patterns against temporal and spatial dimensions since the Miocene in the Psammobates tentorius species complex, using multiple types of DNA markers and niche modelling analyses. Cladogenesis in P. tentorius started in the late Miocene (11.63–5.33 Ma) when populations dispersed from north to south to form two geographically isolated groups. The northern group diverged into a clade north of the Orange River (OR), followed by the splitting of the group south of the OR into a western and an interior clade. The latter divergence corresponded to the intensifcation of the cold Benguela current, which caused western aridifcation and rainfall seasonality. In the south, tectonic uplift and subsequent exhumation, together with climatic fuctuations seemed responsible for radiations among the four southern clades since the late Miocene. We found that each clade occurred in a habitat shaped by diferent climatic parameters, and that the niches difered substantially among the clades of the northern group but were similar among clades of the southern group. Conclusion: Climatic shifts, and biome and geographic changes were possibly the three major driving forces shaping cladogenesis and genetic structure in Southern African tortoise species. Our results revealed that the cladogenesis of the P. tentorius species complex was probably shaped by environmental cooling, biome shifts and topographic uplift in Southern Africa since the late Miocene. The Last Glacial Maximum (LGM) may have impacted the distribution of P. tentorius substantially. We found the taxonomic diversify of the P. tentorius species complex to be highest in the Greater Cape Floristic Region. All seven clades discovered warrant conservation attention, particularly Ptt-B–Ptr, Ptt-A and Pv-

Posthypoxic encephalopathy in patients after cardiac surgery: etiological, pathogenetic, and clinical aspects (a literature review)

Post-hypoxic encephalopathy is a brain damage manifested by neurological, neuropsychiatric, and mental disorders, which is caused by a reduction in cerebral blood flow and by a resultant effect of an episode of hypoxia of various etiology and duration. This complication is most characteristic of patients who have undergone cardiac surgery in view of the high prevalence and severity of clinical manifestations, worse quality of life, the longer length of hospital stay, and the higher cost of treatment and rehabilitation. To determine the individual management tactics for such patients, combining both successful surgical treatment, by reducing perioperative stress, and prevention of cerebral complications, it is necessary to analyze the patterns of their development. The role of pathophysiological risk factors, including preoperative, perioperative and postoperative ones, for posthypoxic encephalopathy, is considered. Its preoperative risk factors include age, gender, concomitant diseases, education level, and cognitive functions before surgery, cardiac morphofunctional changes, and depressive disorders. There are surgery-related (type and duration of anesthesia, operating-suite temperatures, and hyperglycemia) and postoperative (pain syndrome after surgical intervention, sleep disorders, and the environment) risk factors. Emphasis is placed on the technical characteristics of on-pump operations, among which there are cerebral hypoperfusion, microembolism, non-pulsatile flow, and duration of extracorporeal circulation. Classifications of cerebral complications are presented. Different types of brain dysfunction are analyzed to assess their incidence rates, clinical features, and dynamics in the postoperative period

Posthypoxic encephalopathy in patients undergoing coronary artery bypass surgery: clinical, neuropsychological, and neuroimaging aspects

Posthypoxic encephalopathy is a frequent complication after coronary artery bypass surgery (CABG), which includes stroke, early postoperative delirium, and postoperative cognitive dysfunction (PCD). The more pronounced prevalence and severity of the latter during surgery using extracorporeal circulation are currently being discussed.Objective: to analyze various types of cerebral dysfunction in patients undergoing CABG and to determine the role of perioperative factors in its development.Patients and methods. The investigation enrolled 53 patients who had undergone elective CABG for coronary heart disease. Group 1 included 20 patients who had undergone beating-heart surgery; Group 2 comprised 33 patients, in whom CABG had been performed using extracorporeal circulation (ECC). Neuropsychological testing and brain magnetic resonance imaging (MRI) (structural and functional techniques) were carried out.Results and discussion. Posthypoxic encephalopathy was diagnosed in 10 and 67% of patients in Group 1 and 2, respectively (p=0.05); these were precisely all the three types of brain dysfunction which were observed in Group 2 patients. Factors, such as over 70 years of age; median level of education; smoking; body mass index >30 kg/m2 ; ejection fraction <50%; class III effort angina; >210-min surgery duration; >55-min aortic ligation; and >115-min ECC, showed a statistically significant association with the onset of PCD (p<0.05). In Group 2, MRI revealed a weaker positive functional relationship of the medial prefrontal cortex with the posterior cingulate gyrus (<0.005); 18% of patients were found to have acute ischemic zones.Conclusion. Surgical myocardial revascularization using ECC is associated with a greater likelihood of PCD than beating-heart CABG. The factors that favored the development of PCD, such as increased age, low preoperative cognitive status, smoking, and long-term use of ECC, were identified when applying ECC

Взаимосвязь между вирусом SARS-COV-2 и аутоиммунными неврологическими заболеваниями

Since the onset of the SARS-CoV-2 infection, there has been an increase in the number of reports of patients who have experienced the development of autoimmune neurological disorders. It is assumed that such an increase in the incidence rate may occur due to an abnormal immune-mediated response of the body to the pathogenic impact of SARS-CoV-2. This article discusses the possibility of the influence of SARS-CoV-2 on the onset and exacerbation of the course of autoimmune neurological disorders, possible pathogenetic factors and mechanisms, and analyzes the features of the clinical picture and therapy. The article includes foreign and Russian scientific data and clinical observations of cases of Guillain-Barré syndrome, multiple sclerosis, acute disseminated encephalomyelitis, myasthenia gravis and other autoimmune diseases that have changed their typical course on the background of COVID-19.С начала массового распространения инфекции, вызванной вирусом SARS-CoV-2, возросло количество сообщений об увеличении частоты аутоиммунных неврологических расстройств. Предполагается, что подобное повышение уровня заболеваемости может возникать вследствие аномального иммуноопосредованного ответа организма на патогенное воздействие SARS-CoV-2. В данной статье рассматривается возможность влияния вируса SARS-CoV-2 на возникновение и обострение течения аутоиммунных неврологических расстройств, обсуждаются возможные патогенетические факторы и механизмы, анализируются особенности клинической картины и терапии. Представлены зарубежные и российские научные данные, клинические наблюдения случаев синдрома Гийена – Барре, рассеянного склероза, острого диссеминированного энцефаломиелита, миастении и других аутоиммунных заболеваний, возникших или изменивших свое типичное течение на фоне COVID-19