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Most hyperbaric medicine reports concentrate on the patient and his morbidities. In addition to the well-known indications for hyperbaric oxygen therapy (HBOT), we cannot discount possible side effects. Among medical staff regularly exposed to hyperbaric conditions the best described so far is decompression sickness. A non-invasive and easily available way to assess cognitive functioning involves the use of the critical flicker fusion frequency (CFFF) test. In the current study, the flicker test was performed several times on 21 subjects, both under normobaric and hyperbaric conditions. The test was conducted using the device that flickering was programmed according to the method of limits. While in the hyperbaric chamber, 15 of the participants breathed oxygen to reduce the risk of decompression sickness. Flicker and fusion frequencies differed from each other in both normo- and hyperbaric conditions (p < 0.01). CFFF results were dependent on oxygen breathing during decompression.

Introduction: The phenomenon known as periodic limb movements in sleep (PLMS) has been linked to a change in autonomic nervous system (ANS) activity and its effect on circulatory regulation. Autonomic dysfunction or dysregulation in patients with PLMS has been described in some domains; however, any relationship between heart rate variability (HRV) and PLMS has not been clearly established. HRV analysis is a recognised, non-invasive research method that describes the influence of the ANS on heart rate (HR). The aim of our study was to further investigate the dysregulation of autonomic HR control in patients with PLMS., Material and Methods: We undertook a retrospective analysis of the polysomnographic (PSG), demographic and medical data of five patients with a total number of 1,348 PLMS. We analysed HR, HRV HF, systolic blood pressure (SBP), and diastolic blood pressure (DBP) for 10 heartbeats before the series of PLMS and 10 consecutive heartbeats as beat-to-beat measurements. The presented method of using successive, short, 10 RR interval segments refers to the time-frequency measurement, which is very clear and useful for presenting changes in the calculated parameters over time and thereby illustrating their dynamics. This method allowed us to assess dynamic changes in HRV HF during successive PLMS series. Statistical analysis was performed using IBM SPSS Statistics (v. 28.0.0.0). The Kruskal-Wallis test was performed to find statistically significant changes from baseline., Results: No statistically significant changes in HR, SBP, or DBP were found in our group, although an increase in the value of the HRV HF was noted, suggesting an increase in intracardiac parasympathetic activity during the subsequent series of PLMS., Conclusions: Our study indicates an increase in parasympathetic activity during the appearance of successive PLMS, which, with the simultaneous lack of changes in HR, may suggest an increase in sympathetic activity, and therefore the appearance of so-called 'autonomic co-activation' resulting in the possibility of life-threatening cardiac events., Clinical Implications: Our findings add to the literature information regarding HRV in PLMS, and highlight the need for further studies to elucidate the effects of these conditions on the ANS, and on cardiovascular health.

We first want to thank the authors of the excellent review for their contributions to summarizing the confounders associated with critical flicker fusion frequency (CFFF) [...].

The regular cardiac response to immersion of the face in cold water is reduction in heart rate (HR). The highly individualized and unpredictable course of the cardiodepressive response prompted us to investigate the relationship between the cardiac response to face immersion and the resting HR. The research was conducted with 65 healthy volunteers (37 women and 28 men) with an average age of 21.13 years (20-27 years) and a BMI of 21.49 kg/m 2 (16.60-28.98). The face-immersion test consisted of stopping breathing after maximum inhaling and voluntarily immersing the face in cold water (8-10 °C) for as long as possible. Measurements included determination of minimum, average, and maximum HR at rest and minimum and maximum HR during the cold-water face-immersion test. The results indicate a strong relationship between the cardiodepressive reaction of the immersion of the face and the minimum HR before the test, as well as a relationship between the maximum HR during the test and the maximum HR at rest. The results also indicate a strong influence of neurogenic HR regulation on the described relationships. The parameters of the basal HR can, therefore, be used as prognostic indicators of the course of the cardiac response of the immersion test.

New imaging sequences and biophysical models allow adopting magnetic resonance imaging (MRI) for in vivo myelin mapping in humans. Understanding myelination and remyelination processes in the brain is fundamental from the perspective of proper design of physical exercise and rehabilitation schemes that aim to slow down demyelination in the aging population and to induce remyelination in patients with neurodegenerative diseases. Therefore, in this review we strive to provide a state-of-the art summary of the existing MRI studies in humans focused on the effects of physical activity on myelination/remyelination. We present and discuss four cross-sectional and four longitudinal studies and one case report. Physical activity and an active lifestyle have a beneficial effect on the myelin content in humans. Myelin expansion can be induced in humans throughout the entire lifespan by intensive aerobic exercise. Additional research is needed to determine (1) what exercise intensity (and cognitive novelty, which is embedded in the exercise scheme) is the most beneficial for patients with neurodegenerative diseases, (2) the relationship between cardiorespiratory fitness and myelination, and (3) how exercise-induced myelination affect cognitive abilities., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Kujawa, Marcinkowska, Grzywińska, Waśkow, Romanowski, Szurowska, Winklewski and Szarmach.)

Scuba diving as a recreational activity is becoming increasingly popular. However, the safety of this activity, especially in the out-of-comfort zone, has been discussed worldwide. The latest publications bring conclusions regarding negative effects on cognitive functions. We compare the acute and chronic effects of diving on cognitive functioning depending on the type of dive performed, including recreational, technical and saturation diving. However, the results of research show that acute and chronic effects on cognitive functions can be negative. While acute effects are reversible after the ascent, chronic effects include white matter lesions in magnetic resonance imaging scans. We believe that more investigations should be performed to determine the chronic effects that could be observed after a few months of observations in a group of regular, intense divers. In addition, publications referring to technical divers are very limited, which is disquieting, as this particular group of divers seems to be neglected in research concerning the effects of diving on cognitive functions.

Stroke is a life-threatening condition in which accurate diagnoses and timely treatment are critical for successful neurological recovery. The current acute treatment strategies, particularly non-invasive interventions, are limited, thus urging the need for novel therapeutical targets. Arginine vasopressin (AVP) receptor antagonists are emerging as potential targets to treat edema formation and subsequent elevation in intracranial pressure, both significant causes of mortality in acute stroke. Here, we summarize the current knowledge on the mechanisms leading to AVP hyperexcretion in acute stroke and the subsequent secondary neuropathological responses. Furthermore, we discuss the work supporting the predictive value of measuring copeptin, a surrogate marker of AVP in stroke patients, followed by a review of the experimental evidence suggesting AVP receptor antagonists in stroke therapy. As we highlight throughout the narrative, critical gaps in the literature exist and indicate the need for further research to understand better AVP mechanisms in stroke. Likewise, there are advantages and limitations in using copeptin as a prognostic tool, and the translation of findings from experimental animal models to clinical settings has its challenges. Still, monitoring AVP levels and using AVP receptor antagonists as an add-on therapeutic intervention are potential promises in clinical applications to alleviate stroke neurological consequences.

A characteristic feature of the cardiac response to diving is the uncertainty in predicting individual course. The aim of the study was to determine whether resting regulatory heart rate determinants assessed before diving may be predictors of cardiac response in a simulated diving test. The research was conducted with 65 healthy volunteers (37 women and 28 men) with an average age of 21.13 years (20-27 years) and a BMI of 21.49 kg/m 2 (16.60-28.98). The simulated diving test consisted of stopping breathing after maximum inhaling and voluntarily immersing the face in water (8-10 °C) for as long as possible. The measurements included heart rate variability (HRV) analysis before diving and determination of the course of the cardiac response to diving-minimum and maximum heart rate (HR). The results indicate that minimum HR during diving (MIN&#95;div) is dependent on the short-term HRV measures, which proves the strong influence of the parasympathetic system on the MIN&#95;div. The lack of dependence of MIN&#95;div on short-term HRV in women may be associated with differences in neurogenic HR regulation in women and men. In conclusion, cardiac response to simulated diving is strictly dependent on the autonomic regulation of the heart rhythm under resting conditions. The course of the cardiac response to diving and its relationship with resting HRV appears to be gender dependent.

The aim of this review is to summarise current knowledge about flickering light and the underlying processes that occur during its processing in the brain. Despite the growing interest in the topic of flickering light, its clinical applications are still not well understood. Studies using EEG indicate an appearing synchronisation of brain wave frequencies with the frequency of flickering light, and hopefully, it could be used in memory therapy, among other applications. Some researchers have focused on using the flicker test as an indicator of arousal, which may be useful in clinical studies if the background for such a relationship is described. Since flicker testing has a risk of inducing epileptic seizures, however, every effort must be made to avoid high-risk combinations, which include, for example, red-blue light flashing at 15 Hz. Future research should focus on the usage of neuroimaging methods to describe the specific neuropsychological and neurophysiological processes occurring in the brain during the processing of flickering light so that its clinical utility can be preliminarily determined and randomised clinical trials can be initiated to test existing reports.

The arginine vasopressin (AVP), a neurohypophysial hormone, is synthesized within specific sites of the central nervous system and axonally transported to multiple areas, acting as a neurotransmitter/ neuromodulator. In this context, AVP acts primarily through vasopressin receptors A and B and is involved in regulating complex social and cognition behaviors and basic autonomic function. Many earlier studies have shown that AVP as a neuromodulator affects synaptic plasticity. This review updates our current understanding of the underlying molecular mechanisms by which AVP affects synaptic plasticity. Moreover, we discuss AVP modulatory effects on event-related potentials and blood oxygen level-dependent responses in specific brain structures, and AVP effects on the network level oscillatory activity. We aimed at providing an overview of the AVP effects on the brain from the synaptic to the network level., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Thank you very much for your interest and comments [...].

Aim of the Study: The aim of this study was to assess the diagnostic value of diffusion tensor imaging (DTI) in patients with symptoms of cervical myelopathy. Detailed goals included determining the diagnostic effectiveness of quantitative parameters, i.e. fractional anisotropy (FA) and apparent diffusion coefficient (ADC), in the diagnosis of cervical myelopathy, and the correlation between these parameters and clinical symptoms., Clinical Rationale for the Study: The demonstration of an ischaemic focus in the spinal cord by standard magnetic resonance imaging (MRI) methods is associated with already accomplished spinal cord damage, and of course limited treatment options. Therefore, finding a new examination protocol that allows early diagnosis of myelopathic focus, before the onset of full neurological symptoms, has become a priority in the diagnosis and treatment of spine diseases. Such an examination increases the chances of correctly qualifying the patient for conservative vs. surgical treatment., Material and Methods: Between 2013 and 2017, 128 adults with clinical signs of cervical myelopathy were examined, and were divided into four symptomatic subgroups. A control group consisted of 37 healthy volunteers. DTI values were measured at the level of C2/C3, and at the most severe stenosis of the spine., Results: In patients with cervical spondylotic myelopathy (CSM), the ADC values were significantly higher (p < 0.001), and FA values were significantly lower (p < 0.001), than in healthy volunteers at the stenotic level. There were significant differences in DTI parameters between the clinical subgroups (p < 0.001)., Conclusions and Clinical Implications: Changes in DTI parameters indicate a microstructural disorder of the core which is not visible in a structural MRI. FA and ADC values measured at the level of the most severe stenosis of the spinal canal allow the differentiation of patients with myelopathy of varying degrees of clinical severity. Extending standard MRI to include assessment of FA and ADC may be helpful in deciding treatment modalities (conservative vs. surgical) for patients with visible canal stenosis without full neurological symptoms. This may be useful in selecting patients for urgent rehabilitative treatment. This study is a starting point for further research, i.e. an evaluation of the extent of FA and ADC lesion withdrawal after surgical treatment.

Introduction: We hypothesized that, based on magnetic resonance enterography (MRE) and the apparent diffusion coefficient (ADC), measured in the affected parts of the intestine, it is possible to effectively differentiate active and chronic phases of Crohn's disease., Aim: To create a multidimensional diagnostic model for differentiating between the phases of Crohn's disease., Material and Methods: This study included 125 patients - 55 women (aged 19 to 66 years) and 70 men (aged 12 to 67 years) - who underwent MRE and ADC measurement for the first time., Results: The group of potential explanatory variables comprised 11 variables, including the thickness and length of the occupied section, number of lymph nodes, layered bowel wall enhancement, total transitions on fat tissue, and features of restricted diffusion. The final discrimination model was based on 2 variables: ADC (A) and layered bowel wall enhancement (W). Active Crohn's disease was defined as -6.339 + 4.747 × W + 0.008 × A, while chronic Crohn's disease was defined as -11.365 + 2.812 × W + 0.012 × A. Definitive diagnosis was based on histological examination of material collected during ileocolonoscopy in 96 patients, surgery with subsequent histopathological examination in 17 patients, and capsule endoscopy in 12 patients., Conclusions: The predictive model described here could identify the active form of Crohn's disease with a probability of 93.06% and the chronic form with a probability of 75.57%. The use of classic MRE layered bowel wall enhancement and a DWI-based ADC metric eliminates the main shortcomings of both approaches., Competing Interests: The authors declare no conflict of interest., (Copyright © 2022 Termedia.)

Objectives: To evaluate the effect of L-carnitine (LC) in combination with leucine supplementation on muscle strength and muscle hypertrophy in aged women participating in a resistance exercise training (RET) program., Design/setting/participants: Thirty-seven out of sixty (38.3% dropout) healthy women aged 60-75 years (mean 67.6 ± 0.7 years) completed the intervention in one of three groups. One of the supplemented groups received 1 g of L-carnitine-L-tartrate in combination with 3 g of L-leucine per day (LC+L group; n = 12), and the second supplemented group received 4 g of L-leucine per day (L group; n = 13). The control group (CON group; n = 12) received no supplementation., Intervention: All three groups completed the same RET protocol involving exercise sessions twice per week for 24 weeks., Measurements: Before and after the experiment, participants performed isometric and isokinetic muscle strength testing on the Biodex dynamometer. The cross-sectional areas of the major knee extensors and total thigh muscles were assessed using magnetic resonance imaging. Fasting serum levels of insulin-like growth factor-1 (IGF-1), myostatin and decorin, and plasma levels of total carnitine (TC) and trimethylamine-N-oxide (TMAO) levels were measured., Results: The 24-week RET significantly increased muscle strength and muscle volume, but the group and time interactions were not significant for the muscle variables analyzed. Plasma total carnitine increased only in the LC+L group (p = 0.009). LC supplementation also caused a significant increase in plasma TMAO, which was higher after the intervention in the LC+L group than in the L (p &lt; 0.001), and CON (p = 0.005) groups. The intervention did not change plasma TMAO concentration in the L (p = 0.959) and CON (p = 0.866) groups. After the intervention serum decorin level was higher than before in both supplemented groups combined (p = 0.012), still not significantly different to post intervention CON (p = 0.231). No changes in serum IGF-1 and myostatin concentrations and no links between the changes in blood markers and muscle function or muscle volume were observed., Conclusions: LC combined with leucine or leucine alone does not appear to improve the effectiveness of RET.

Background: The aim of the study was to investigate the effect of mild cerebral hypoxia on haemoglobin oxygenation (HbO 2 ), cerebrospinal fluid dynamics and cardiovascular physiology. To achieve this goal, four signals were recorded simultaneously: blood pressure, heart rate / electrocardiogram, HbO 2  from right hemisphere and changes of subarachnoid space (SAS) width from left hemisphere. Signals were registered from 30 healthy, young participants (2 females and 28 males, body mass index = 24.5 ± 2.3 kg/m 2 , age 30.8 ± 13.4 years)., Results: We analysed the recorded signals using wavelet transform and phase coherence. We demonstrated for the first time that in healthy subjects exposed to mild poikilokapnic hypoxia there were increases in very low frequency HbO 2 oscillations (< 0.052 Hz) in prefrontal cortex. Additionally, SAS fluctuation diminished in the whole frequency range which could be explained by brain oedema., Conclusions: Consequently the study provides insight into mechanisms governing brain response to a mild hypoxic challenge. Our study supports the notion that HbO 2 and SAS width monitoring might be beneficial for patients with acute lung disease., (© 2021. The Author(s).)

This review presents the current knowledge of the usage of critical flicker fusion frequency (CFF) in human and animal model studies. CFF has a wide application in different fields, especially as an indicator of cortical arousal and visual processing. In medicine, CFF may be helpful for diagnostic purposes, for example in epilepsy or minimal hepatic encephalopathy. Given the environmental studies and a limited number of other methods, it is applicable in diving and hyperbaric medicine. Current research also shows the relationship between CFF and other electrophysiological methods, such as electroencephalography. The human eye can detect flicker at 50-90 Hz but reports are showing the possibility to distinguish between steady and modulated light up to 500 Hz. Future research with the use of CFF is needed to better understand its utility and application.

The precise mechanisms connecting the cardiovascular system and the cerebrospinal fluid (CSF) are not well understood in detail. This paper investigates the couplings between the cardiac and respiratory components, as extracted from blood pressure (BP) signals and oscillations of the subarachnoid space width (SAS), collected during slow ventilation and ventilation against inspiration resistance. The experiment was performed on a group of 20 healthy volunteers (12 females and 8 males; BMI=22.1±3.2 kg/m2; age 25.3±7.9 years). We analysed the recorded signals with a wavelet transform. For the first time, a method based on dynamical Bayesian inference was used to detect the effective phase connectivity and the underlying coupling functions between the SAS and BP signals. There are several new findings. Slow breathing with or without resistance increases the strength of the coupling between the respiratory and cardiac components of both measured signals. We also observed increases in the strength of the coupling between the respiratory component of the BP and the cardiac component of the SAS and vice versa. Slow breathing synchronises the SAS oscillations, between the brain hemispheres. It also diminishes the similarity of the coupling between all analysed pairs of oscillators, while inspiratory resistance partially reverses this phenomenon. BP-SAS and SAS-BP interactions may reflect changes in the overall biomechanical characteristics of the brain.

The aim of the study was to compare simultaneously recorded a NIR-T/BSS and NIRS signals from healthy volunteers. NIR-T/BSS is a device which give an ability to non-invasively detect and monitor changes in the subarachnoid space width (SAS). Experiments were performed on a group of 30 healthy volunteers (28 males and 2 females, age 30.8 ± 13.4 years, BMI = 24.5 ± 2.3 kg/m 2 ). We analysed recorded signals using analysis methods based on wavelet transform (WT) for the wide frequency range from 0.0095 to 2 Hz. Despite the fact that both devices use a similar radiation source both signals are distinct from each other. We found statistically significant differences for WT amplitude spectra between both signals. Additionally, we showed different relationships of both signals to blood pressure. Collectively, based on the present findings and those of previous studies, we can conclude that the combination of NIR-T/BSS or NIRS signals and time-frequency analysis opens new frontiers in science, and give possibility to understand and diagnosis of various neurodegenerative and ageing related diseases to improve diagnostic procedures and patient prognosis.

A high-fat diet (HFD) induces changes in gut microbiota leading to activation of pro-inflammatory pathways, and obesity, as a consequence of overnutrition, exacerbates inflammation, a known risk factor not only for cancer. However, experimental data showed that the composition of dietary fat has a greater impact on the pathogenesis of cancer than the total fat content in isocaloric diets. Similarly, human studies did not prove that a decrease in total fat intake is an effective strategy to combat cancer. Saturated fat has long been considered as harmful, but the current consensus is that moderate intake of saturated fatty acids (SFAs), including palmitic acid (PA), does not pose a health risk within a balanced diet. In regard to monounsaturated fat, plant sources are recommended. The consumption of plant monounsaturated fatty acids (MUFAs), particularly from olive oil, has been associated with lower cancer risk. Similarly, the replacement of animal MUFAs with plant MUFAs decreased cancer mortality. The impact of polyunsaturated fatty acids (PUFAs) on cancer risk depends on the ratio between ω-6 and ω-3 PUFAs. In vivo data showed stimulatory effects of ω-6 PUFAs on tumour growth while ω-3 PUFAs were protective, but the results of human studies were not as promising as indicated in preclinical reports. As for trans FAs (TFAs), experimental data mostly showed opposite effects of industrially produced and natural TFAs, with the latter being protective against cancer progression, but human data are mixed, and no clear conclusion can be made. Further studies are warranted to establish the role of FAs in the control of cell growth in order to find an effective strategy for cancer prevention/treatment.

l-carnitine supplementation has been used for cardiovascular health protection for a long time. Recently, trimethylamine-N-oxide (TMAO), which is an end product of l-carnitine metabolism via the activity of microbiota, has been identified as a cardiovascular disease (CVD) biomarker. The aim of this study was to assess the effect of 6 months of l-carnitine supplementation in a group of aged women engaged in a regular physical training. Platelet mitochondrial DNA methylation, an emerging and innovative biomarker, lipid profile and TMAO levels have been measured. TMAO increased after l-carnitine supplementation (before 344.3 ± 129.8 ng/mL vs. after 2216.8 ± 1869.0 ng/mL; n = 9; paired t-test, p = 0.02). No significant effects on TMAO were exerted by training alone ( n = 9) or by l-leucine supplementation ( n = 12). TMAO levels after 6 months of l-carnitine supplementation were associated with higher low-density lipoprotein-cholesterol (LDL-c) (Spearman Rho = 0.518, p = 0.003) and total cholesterol (TC) (Spearman Rho = 0.407, p = 0.026) levels. l-carnitine supplementation increased D-loop methylation in platelets (+6.63%; paired t-test, p = 0.005). D-loop methylation was not directly correlated to the TMAO augmentation observed in the supplemented group, but its increase inversely correlated with TC (Pearson coefficient = -0.529, p = 0.029) and LDL-c (Pearson coefficient = -0.439, p = 0.048). This evidence supports the hypothesis that the correlation between l-carnitine, TMAO and atherosclerosis might be more complex than already postulated, and the alteration of mitochondrial DNA (mtDNA) methylation in platelets could be involved in the pathogenesis of this multifactorial disease.

Negative intrathoracic pressure (nITP) is generated by the respiratory muscles during inspiration to overcome inspiratory resistance, thus enabling lung ventilation. Recently developed noninvasive techniques have made it possible to assess the effects of nITP in real time in several physiological aspects such as systemic blood pressure (BP), intracranial pressure (ICP), and cerebral blood flow (CBF). It has been shown that nITP from 0 to -20 cmH 2 O elevates BP and diminishes ICP, which facilitates brain perfusion. The effects of nITP from -20 to -40 cmH 2 O on BP, ICP, and CBF remain largely unrecognized, yet even nITP at -40 cmH 2 O may facilitate CBF by diminishing ICP. Importantly, nITP from -20 to -40 cmH 2 O has been documented in adults in commonly encountered obstructive sleep apnea, which justifies research in this area. Recent revelations about interactions between ICP and BP have opened up new fields of research in physiological regulation and the pathophysiology of common diseases, such as hypertension, brain injury, and respiratory disorders. A better understanding of these interactions may translate directly into new therapies in various fields of clinical medicine.

The aim of the study was to assess cardiac and respiratory blood pressure (BP) and subarachnoid space (SAS) width oscillations during the resting state for slow and fast breathing and breathing against inspiratory resistance. Experiments were performed on a group of 20 healthy volunteers (8 males and 12 females; age 25.3 ± 7.9 years; BMI = 22.1 ± 3.2 kg/m 2 ). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography. SAS signals were recorded using an SAS monitor. Oxyhaemoglobin saturation (SaO 2 ) and end-tidal CO 2 (EtCO 2 ) were measured using a medical monitoring system. Procedure 1 consisted of breathing spontaneously and at controlled rates of 6 breaths/minute and 6 breaths/minute with inspiratory resistance for 10 minutes. Procedure 2 consisted of breathing spontaneously and at controlled rates of 6, 12 and 18 breaths/minute for 5 minutes. Wavelet analysis with the Morlet mother wavelet was applied for delineation of BP and SAS signals cardiac and respiratory components. Slow breathing diminishes amplitude of cardiac BP and SAS oscillations. The overall increase in BP and SAS oscillations during slow breathing is driven by the respiratory component. Drop in cardiac component of BP amplitude evoked by slow-breathing may be perceived as a cardiovascular protective mechanism to avoid target organ damage. Further studies are warranted to assess long-term effects of slow breathing.

Objectives: We tested the hypothesis that computed tomography (CT) perfusion markers of cerebral microcirculation would improve 36 months after internal carotid artery stenting for symptomatic carotid stenosis while results obtained 6-8 weeks after the stenting procedure would yield a predictive value., Methods: We recruited consecutive eligible patients with >70% symptomatic carotid stenosis with a complete circle of Willis and normal vertebral arteries to the observational cohort study. We detected changes in the cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) and permeability surface area-product (PS) before and after carotid stenting. We have also compared the absolute differences in the ipsilateral and contralateral CT perfusion markers before and after stenting. The search for regression models of "36 months after stenting" results was based on a stepwise analysis with bidirectional elimination method., Results: A total of 34 patients completed the 36 months follow-up (15 females, mean age of 69.68±S.D. 7.61 years). At 36 months after stenting, the absolute values for CT perfusion markers had improved: CBF (ipsilateral: +7.76%, contralateral: +0.95%); CBV (ipsilateral: +5.13%, contralateral: +3.00%); MTT (ipsilateral: -12.90%; contralateral: -5.63%); TTP (ipsilateral: -2.10%, contralateral: -4.73%) and PS (ipsilateral: -35.21%, contralateral: -35.45%). MTT assessed 6-8 weeks after stenting predicted the MTT value 36 months after stenting (ipsilateral: R2=0.867, contralateral R2=0.688)., Conclusions: We have demonstrated improvements in CT perfusion markers of cerebral microcirculation health that persist for at least 3 years after carotid artery stenting in symptomatic patients. MTT assessed 6-8 weeks after stenting yields a predictive value.

In this narrative review, a theoretical framework on the crosstalk between physical exercise and blood-brain barrier (BBB) permeability is presented. We discuss the influence of physical activity on the factors affecting BBB permeability such as systemic inflammation, the brain renin-angiotensin and noradrenergic systems, central autonomic function and the kynurenine pathway. The positive role of exercise in multiple sclerosis and Alzheimer's disease is described. Finally, the potential role of conditioning as well as the effect of exercise on BBB tight junctions is outlined. There is a body of evidence that regular physical exercise diminishes BBB permeability as it reinforces antioxidative capacity, reduces oxidative stress and has anti-inflammatory effects. It improves endothelial function and might increase the density of brain capillaries. Thus, physical training can be emphasised as a component of prevention programs developed for patients to minimise the risk of the onset of neuroinflammatory diseases as well as an augmentation of existing treatment. Unfortunately, despite a sound theoretical background, it remains unclear as to whether exercise training is effective in modulating BBB permeability in several specific diseases. Further research is needed as the impact of exercise is yet to be fully elucidated.

The use of the diffusion tensor imaging (DTI) is rapidly growing in the neuroimaging field. Nevertheless, rigorously performed quantitative validation of DTI pathologic metrics remains very limited owing to the difficulty in co-registering quantitative histology findings with magnetic resonance imaging. The aim of this review is to summarize the existing state-of-the-art knowledge with respect to axial (λ ║ ) and radial (λ ┴ ) diffusivity as DTI markers of axonal and myelin damage, respectively. First, we provide technical background for DTI and briefly discuss the specific organization of white matter in bundles of axonal fibers running in parallel; this is the natural target for imaging based on diffusion anisotropy. Second, we discuss the four seminal studies that paved the way for considering axial (λ ║ ) and radial (λ ┴ ) diffusivity as potential in vivo surrogate markers of axonal and myelin damage, respectively. Then, we present difficulties in interpreting axial (λ ║ ) and radial (λ ┴ ) diffusivity in clinical conditions associated with inflammation, edema, and white matter fiber crossing. Finally, future directions are highlighted. In summary, DTI can reveal strategic information with respect to white matter tracts, disconnection mechanisms, and related symptoms. Axial (λ ║ ) and radial (λ ┴ ) diffusivity seem to provide quite consistent information in healthy subjects, and in pathological conditions with limited edema and inflammatory changes. DTI remains one of the most promising non-invasive diagnostic tools in medicine.

Abnormal cerebrospinal fluid (CSF) pulsatility has been implicated in patients suffering from various diseases, including multiple sclerosis and hypertension. CSF pulsatility results in subarachnoid space (SAS) width changes, which can be measured with near-infrared transillumination backscattering sounding (NIR-T/BSS). The aim of this study was to combine NIR-T/BSS and wavelet analysis methods to characterise the dynamics of the SAS width within a wide range of frequencies from 0.005 to 2 Hz, with low frequencies studied in detail for the first time. From recordings in the resting state, we also demonstrate the relationships between SAS width in both hemispheres of the brain, and investigate how the SAS width dynamics is related to the blood pressure (BP). These investigations also revealed influences of age and SAS correlation on the dynamics of SAS width and its similarity with the BP. Combination of NIR-T/BSS and time-frequency analysis may open up new frontiers in the understanding and diagnosis of various neurodegenerative and ageing related diseases to improve diagnostic procedures and patient prognosis.

The aim of this study was to assess regional perfusion at baseline and regional cerebrovascular resistance (CVR) to delayed acetazolamide challenge in subjects with chronic carotid artery stenosis. Sixteen patients (ten males) aged 70.94±7.71 with carotid artery stenosis ≥ 90% on the ipsilateral side and ≤ 50% on the contralateral side were enrolled into the study. In all patients, two computed tomography perfusion examinations were carried out; the first was performed before acetazolamide administration and the second 60 minutes after injection. The differences between mean values were examined by paired two-sample t-test and alternative nonparametric Wilcoxon's test. Normality assumption was examined using W Shapiro-Wilk test. The lowest resting-state cerebral blood flow (CBF) was observed in white matter (ipsilateral side: 18.4±6.2; contralateral side: 19.3±6.6) and brainstem (ipsilateral side: 27.8±8.5; contralateral side: 29.1±10.8). Grey matter (cerebral cortex) resting state CBF was below the normal value for subjects of this age: frontal lobe - ipsilateral side: 30.4±7.0, contralateral side: 33.7±7.1; parietal lobe - ipsilateral side: 36.4±11.3, contralateral side: 42.7±9.9; temporal lobe - ipsilateral side: 32.5±8.6, contralateral side: 39.4±10.8; occipital lobe - ipsilateral side: 24.0±6.0, contralateral side: 26.4±6.6). The highest resting state CBF was observed in the insula (ipsilateral side: 49.2±17.4; contralateral side: 55.3±18.4). A relatively high resting state CBF was also recorded in the thalamus (ipsilateral side: 39.7±16.9; contralateral side: 41.7±14.1) and cerebellum (ipsilateral side: 41.4±12.2; contralateral side: 38.1±11.3). The highest CVR was observed in temporal lobe cortex (ipsilateral side: +27.1%; contralateral side: +26.1%) and cerebellum (ipsilateral side: +27.0%; contralateral side: +34.6%). The lowest CVR was recorded in brain stem (ipsilateral side: +20.2%; contralateral side: +22.2%) and white matter (ipsilateral side: +18.1%; contralateral side: +18.3%). All CBF values were provided in milliliters of blood per minute per 100 g of brain tissue (ml/100g/min). Resting state circulation in subjects with carotid artery stenosis is low in all analysed structures with the exception of insula and cerebellum. Acetazolamide challenge yields relatively uniform response in both hemispheres in the investigated population. Grey matter is more reactive to acetazolamide challenge than white matter or brainstem.

Aims: The aim of the study was to examine the effects of melatonin impact on changes in haematological profile, biomarkers of oxidative stress (dienes conjugates, malondialdehyde (MDA), oxidatively modified protein levels, total antioxidant capacity and antioxidant enzyme activity) in liver, muscle, kidney and erythrocytes, and glycated haemoglobin (HBA1c) in mice during acute ethanol stress., Methods: Assays were carried out in quadruplicate: control, melatonin (10 mg/kg, 10 days), acute ethanol stress (0.75 g/kg/day, 10 days) and acute ethanol stress plus melatonin groups., Results: Acute ethanol stress caused a significant increase in the total number of white blood cells (WBC), especially neutrophils in the blood, and HBA1c levels vs. control mice. The correlation between lipid peroxidation and the glycated haemoglobin level was shown (r = 0.93, P = 0.007). Ethanol reduced the antioxidant capacity by increasing reactive oxygen species (ROS) production and the level of oxidatively modified protein content, diene conjugates and MDA. Melatonin administration in animals during acute ethanol stress reduced antioxidant stress biomarkers, WBC, HBA1c levels and ROS production., Conclusions: Melatonin had protective effects on liver, kidney and muscle tissues by preventing the intensive lipid peroxidation processes in initial (diene conjugation production) and late stages (MDA level), and significantly reduced the level of aldehyde and ketone protein derivatives. Furthermore, melatonin restored elevated WBC count and HBA1c level and diminished ROS production., Short Summary: Ethanol reduces antioxidant capacity and leads to exaggerated reactive oxygen species production and consequent increases in oxidatively modified proteins. Melatonin exerts protective effects by preventing the intensive lipid peroxidation processes. Melatonin significantly reduces the level of aldehyde and ketone protein derivatives, restores glycated haemoglobin level and white blood cell count., (© The Author 2017. Medical Council on Alcohol and Oxford University Press. All rights reserved.)

Background and Objective: Respiration is known to affect cerebrospinal fluid (CSF) movement. We hypothesised that increased inspiratory resistance would affect the dynamic relationship between blood pressure (BP) changes and subarachnoid space width (SAS) oscillations., Methods: Experiments were performed in a group of 20 healthy volunteers undergoing controlled intermittent Mueller Manoeuvres (the key characteristic of the procedure is that a studied person is subjected to a controlled, increased inspiratory resistance which results in marked potentiation of the intrathoracic negative pressure). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography; oxyhaemoglobin saturation with an ear-clip sensor; end-tidal CO2 with a gas analyser; cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a new method i.e. near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the BP and SAS oscillations coupling., Results: Initiating Mueller manoeuvres evoked cardiac SAS component decline (-17.8%, P<0.001), systolic BP, diastolic BP and HR increase (+6.3%, P<0.001; 6.7%, P<0.001 and +2.3%, P<0.05, respectively). By the end of Mueller manoeuvres, cardiac SAS component and HR did not change (+2.3% and 0.0%, respectively; both not statistically significant), but systolic and diastolic BP was elevated (+12.6% and +8.9%, respectively; both P<0.001). With reference to baseline values there was an evident decrease in wavelet coherence between BP and SAS oscillations at cardiac frequency in the first half of the Mueller manoeuvres (-32.3%, P<0.05 for left hemisphere and -46.0%, P<0.01 for right hemisphere) which was followed by subsequent normalization at end of the procedure (+3.1% for left hemisphere and +23.1% for right hemisphere; both not statistically significant)., Conclusions: Increased inspiratory resistance is associated with swings in the cardiac contribution to the dynamic relationship between BP and SAS oscillations. Impaired cardiac performance reported in Mueller manoeuvres may influence the pattern of cerebrospinal fluid pulsatility.

Failure of the blood-brain barrier (BBB) is a critical event in the development and progression of diseases such as acute ischemic stroke, chronic ischemia or small vessels disease that affect the central nervous system. It is not known whether BBB breakdown in subjects with chronic carotid artery stenosis can be restrained with postoperative recovery of cerebral perfusion. The aim of the study was to assess the short-term effect of internal carotid artery stenting on basic perfusion parameters and permeability surface area-product (PS) in such a population. Forty subjects (23 males) with stenosis of >70% within a single internal carotid artery and neurological symptoms who underwent a carotid artery stenting procedure were investigated. Differences in the following computed tomography perfusion (CTP) parameters were compared before and after surgery: global cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) and PS. PS acquired by CTP is used to measure the permeability of the BBB to contrast material. In all baseline cases, the CBF and CBV values were low, while MTT and TTP were high on both the ipsi- and contralateral sides compared to reference values. PS was approximately twice the normal value. CBF was higher (+6.14%), while MTT was lower (-9.34%) on the contralateral than on the ipsilateral side. All perfusion parameters improved after stenting on both the ipsilateral (CBF +22.66%; CBV +18.98%; MTT -16.09%, TTP -7.62%) and contralateral (CBF +22.27%, CBV +19.72%, MTT -14.65%, TTP -7.46%) sides. PS decreased by almost half: ipsilateral -48.11%, contralateral -45.19%. The decline in BBB permeability was symmetrical on the ipsi- and contralateral sides to the stenosis. Augmented BBB permeability can be controlled by surgical intervention in humans.

Background: Acute hypoxia exerts strong effects on the cardiovascular system. Heart-generated pulsatile cerebrospinal fluid motion is recognised as a key factor ensuring brain homeostasis. We aimed to assess changes in heart-generated coupling between blood pressure (BP) and subarachnoid space width (SAS) oscillations during hypoxic exposure., Methods: Twenty participants were subjected to a controlled decrease in oxygen saturation (SaO2 = 80%) for five minutes. BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography, oxyhaemoglobin saturation with an ear-clip sensor, end-tidal CO2 with a gas analyser, and cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a recently-developed method called near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the relationship between BP and SAS oscillations., Results: Gradual increases in systolic, diastolic BP and HR were observed immediately after the initiation of hypoxic challenge (at fifth minute +20.1%, +10.2%, +16.5% vs. baseline, respectively; all P<0.01), whereas SAS remained intact (P = NS). Concurrently, the CBFV was stable throughout the procedure, with the only increase observed in the last two minutes of deoxygenation (at the fifth minute +6.8% vs. baseline, P<0.05). The cardiac contribution to the relationship between BP and SAS oscillations diminished immediately after exposure to hypoxia (at the fifth minute, right hemisphere -27.7% and left hemisphere -26.3% vs. baseline; both P<0.05). Wavelet phase coherence did not change throughout the experiment (P = NS)., Conclusions: Cerebral haemodynamics seem to be relatively stable during short exposure to normobaric hypoxia. Hypoxia attenuates heart-generated BP SAS coupling.

Background: The evidence accumulates that the response to acetazolamide test is delayed on the ipsilateral side to stenosis. However, the effect of acetazolamide beyond 30 min after acetazolamide administration remains unknown. The aim of this study was to assess the diameters of anterior cerebral arteries (ACAs), middle cerebral arteries (MCAs) and posterior cerebral arteries (PCAs) before and 60 min after the acetazolamide test., Materials and Methods: Seventeen patients with carotid artery stenosis ≥ 90% on the ipsilateral side and ≤ 50% on the contralateral side were enrolled into the study. Diagnosis was based on ultrasonography examination and was confirmed using digital subtractive angiography. In all patients, two computed tomography angiography examinations were carried out; the first was performed before the acetazolamide administration, while the second one was carried out 60 min after injections., Results: In response to the acetazolamide test: PCA diameter diminished in both ipsi- and contra-lateral side to stenosis (from 1.31 to 1.24 mm and from 1.23 to 1.15 mm, respectively), ACA and MCA decreased in the contralateral side to the stenosis (from 1.33 to 1.26 mm and from 2.75 to 2.66 mm, respectively), ACA and MCA increased in the ipsilateral side to the stenosis (from 1.29 to 1.46 mm and from 2.77 to 2.96 mm, respectively). All changes were statistically significant., Conclusions: There were significant differences in reactivity to acetazolamide challenge between the internal carotid artery (ICA) and vertebrobasilar circulation in patients suffering from chronic carotid artery stenosis. Within the ICA territory, ACA and MCA responses vary in the affected and not affected side.

Background: The aim of this study was to analyse the morphometry of the intracranial segment of the vertebral artery in the context of clinical usefulness. The results were compared with published data available in full-text archived medical journals., Materials and Methods: More than 100 digital subtraction angiography (DSA) and 3-dimensional (3D) angio-computed tomography (CT) examinations were used to measure the following parameters: the whole and partial length of V4 in characteristic anatomical points, the diameter in three places (on the level of foramen magnum, in point of exit to the posterior inferior cerebellar artery, and in the vertebro-basilar junction), the angle of connection to the vertebral arteries, and all anatomical variations including fenestration, duplication, dolichoectasia or absent artery., Results: The left V4 section was predominant over the right artery, which is manifested by length, width, cases of ectasia and fewer cases of hypoplasia. The incidences of V4 ectasia were identified more often than those documented in the accessible literature, and they were found in the natural location of formation of saccular aneurysms., Conclusions: The presented knowledge of anatomical variation and abnormali-ties of vertebral circulation can improve the accuracy and "safety" of the surgical procedures in this region, help to determine the range of surgical approach and avoid associated complications. The radiological examinations using 3D CT, DSA reveal unlimited observation of anatomical structures in contrast to studies based on cadavers, and can complement the morphometry in anatomical preparations.

Objective: Evaluation of the biomechanical interaction between meniscus and cartilage in medial compartment knee osteoarthritis., Methods: The finite element method was used to simulate knee joint contact mechanics. Three knee models were created on the basis of knee geometry from the Open Knee project. We reduced the thickness of medial cartilages in the intact knee model by approximately 50% to obtain a medial knee osteoarthritis (OA) model. Two variants of medial knee OA model with congruent and incongruent contact surfaces were analysed to investigate the influence of congruency. A nonlinear static analysis for one compressive load case was performed. The focus of the study was the influence of cartilage degeneration on meniscal extrusion and the values of the contact forces and contact areas., Results: In the model with incongruent contact surfaces, we observed maximal compressive stress on the tibial plateau. In this model, the value of medial meniscus external shift was 95.3% greater, while the contact area between the tibial cartilage and medial meniscus was 50% lower than in the congruent contact surfaces model. After the non-uniform reduction of cartilage thickness, the medial meniscus carried only 48.4% of load in the medial compartment in comparison to 71.2% in the healthy knee model., Conclusions: We have shown that the change in articular cartilage geometry may significantly reduce the role of meniscus in load transmission and the contact area between the meniscus and cartilage. Additionally, medial knee OA may increase the risk of meniscal extrusion in the medial compartment of the knee joint., Competing Interests: The authors have declared that no competing interests exist.

Background: Meniscus extrusion is a serious and relatively frequent clinical problem. For this reason the role of different risk factors for this pathology is still the subject of debate. The goal of this study was to verify the results of previous theoretical work, based on the mathematical models, regarding a relationship between the cross-section shape of the meniscus and the risk of its extrusion., Materials and Methods: Knee MRI examination was performed in 77 subjects (43 men and 34 women), mean age 34.99 years (range: 18-49 years), complaining of knee pain. Patients with osteoarthritic changes (grade 3 and 4 to Kellgren classification), varus or valgus deformity and past injuries of the knee were excluded from the study. A 3-Tesla MR device was used to study the relationship between the shape of the lateral meniscus (using slope angle, meniscus-cartilage height and meniscus-bone angle) and the risk of extrusion., Results: Analysis revealed that with values of slope angle and meniscus-bone angle increasing by one degree, the risk of meniscus extrusion raises by 1.157 and 1.078 respectively. Also, an increase in meniscus-cartilage height by 1 mm significantly elevates the risk of extrusion. At the same time it was demonstrated that for meniscus-bone angle values over 42 degrees and slope angle over 37 degrees the risk of extrusion increases significantly., Conclusions: This was the first study to demonstrate a tight correlation between slope angle, meniscus-bone angle and meniscus-cartilage height values in the assessment of the risk of lateral meniscus extrusion. Insertion of the above parameters to the radiological assessment of the knee joint allows identification of patients characterized by an elevated risk of development of this pathology.

Introduction: Using a novel method called near-infrared transillumination backscattering sounding (NIR-T/BSS) that allows for the non-invasive measurement of pial artery pulsation (cc-TQ) and subarachnoid width (sas-TQ) in humans, we assessed the influence of sympathetic activation on the cardiac and respiratory contribution to blood pressure (BP) cc-TQ oscillations in healthy subjects., Methods: The pial artery and subarachnoid width response to handgrip (HGT) and cold test (CT) were studied in 20 healthy subjects. The cc-TQ and sas-TQ were measured using NIR-T/BSS; cerebral blood flow velocity (CBFV) was measured using Doppler ultrasound of the left internal carotid artery; heart rate (HR) and beat-to-beat mean BP were recorded using a continuous finger-pulse photoplethysmography; respiratory rate (RR), minute ventilation (MV), end-tidal CO2 (EtCO2) and end-tidal O2 (EtO2) were measured using a metabolic and spirometry module of the medical monitoring system. Wavelet transform analysis was used to assess the relationship between BP and cc-TQ oscillations., Results: HGT evoked an increase in BP (+15.9%; P<0.001), HR (14.7; P<0.001), SaO2 (+0.5; P<0.001) EtO2 (+2.1; P<0.05) RR (+9.2%; P = 0.05) and MV (+15.5%; P<0.001), while sas-TQ was diminished (-8.12%; P<0.001), and a clear trend toward cc-TQ decline was observed (-11.0%; NS). CBFV (+2.9%; NS) and EtCO2 (-0.7; NS) did not change during HGT. CT evoked an increase in BP (+7.4%; P<0.001), sas-TQ (+3.5%; P<0.05) and SaO2(+0.3%; P<0.05). HR (+2.3%; NS), CBFV (+2.0%; NS), EtO2 (-0.7%; NS) and EtCO2 (+0.9%; NS) remained unchanged. A trend toward decreased cc-TQ was observed (-5.1%; NS). The sas-TQ response was biphasic with elevation during the first 40 seconds (+8.8% vs. baseline; P<0.001) and subsequent decline (+4.1% vs. baseline; P<0.05). No change with respect to wavelet coherence and wavelet phase coherence was found between the BP and cc-TQ oscillations., Conclusions: Short sympathetic activation does not affect the cardiac and respiratory contribution to the relationship between BP-cc-TQ oscillations. HGT and CT display divergent effects on the width of the subarachnoid space, an indirect marker of changes in intracranial pressure.

Purpose: The aim of the study was to assess changes in subarachnoid space width (sas-TQ), the marker of intracranial pressure (ICP), pial artery pulsation (cc-TQ) and cardiac contribution to blood pressure (BP), cerebral blood flow velocity (CBFV) and cc-TQ oscillations throughout the maximal breath hold in elite apnoea divers. Non-invasive assessment of sas-TQ and cc-TQ became possible due to recently developed method based on infrared radiation, called near-infrared transillumination/backscattering sounding (NIR-T/BSS)., Methods: The experimental group consisted of seven breath-hold divers (six men). During testing, each participant performed a single maximal end-inspiratory breath hold. Apnoea consisted of the easy-going and struggle phases (characterised by involuntary breathing movements (IBMs)). Heart rate (HR) was determined using a standard ECG. BP was assessed using the photoplethysmography method. SaO2 was monitored continuously with pulse oximetry. A pneumatic chest belt was used to register thoracic and abdominal movements. Cerebral blood flow velocity (CBFV) was estimated by a 2-MHz transcranial Doppler ultrasonic probe. sas-TQ and cc-TQ were measured using NIR-T/BSS. Wavelet transform analysis was performed to assess cardiac contribution to BP, CBFV and cc-TQ oscillations., Results: Mean BP and CBFV increased compared to baseline at the end of the easy phase and were further augmented by IBMs. cc-TQ increased compared to baseline at the end of the easy phase and remained stable during the IBMs. HR did not change significantly throughout the apnoea, although a trend toward a decrease during the easy phase and recovery during the IBMs was visible. Amplitudes of BP, CBFV and cc-TQ were augmented. sas-TQ and SaO2 decreased at the easy phase of apnoea and further decreased during the IBMs., Conclusions: Apnoea increases intracranial pressure and pial artery pulsation. Pial artery pulsation seems to be stabilised by the IBMs. Cardiac contribution to BP, CBFV and cc-TQ oscillations does not change throughout the apnoea.

Inflammation of forebrain and hindbrain nuclei controlling the sympathetic nervous system (SNS) outflow from the brain to the periphery represents an emerging concept of the pathogenesis of neurogenic hypertension. Angiotensin II (Ang-II) and prorenin were shown to increase production of reactive oxygen species and pro-inflammatory cytokines (interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α)) while simultaneously decreasing production of interleukin-10 (IL-10) in the paraventricular nucleus of the hypothalamus and the rostral ventral lateral medulla. Peripheral chronic inflammation and Ang-II activity seem to share a common central mechanism contributing to an increase in sympathetic neurogenic vasomotor tone and entailing neurogenic hypertension. Both hypertension and obesity facilitate the penetration of peripheral immune cells in the brain parenchyma. We suggest that renin-angiotensin-driven hypertension encompasses feedback and feedforward mechanisms in the development of neurogenic hypertension while low-intensity, chronic peripheral inflammation of any origin may serve as a model of a feedforward mechanism in this condition.

The immune system response and inflammation play a key role in brain injury during and after a stroke. The acute immune response is responsible for secondary brain tissue damage immediately after the stroke, followed by immunosuppression due to sympathetic nervous system activation. The latter increases risk of infection complications, such as pneumonia. The pneumonia-related inflammatory state can release a bystander autoimmune response against central nervous system antigens, thereby initiating a vicious circle. The aim of this review is to summarize the relationship between ischemic stroke, sympathetic nervous system activation and pulmonary infection.

Purpose: The purpose of the study was to assess the responses of pial artery pulsation (cc-TQ) and subarachnoid width (sas-TQ) to acetazolamide challenge in patients with chronic carotid artery stenosis and relate these responses to changes in peak systolic velocity (PSV), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak response (TTP)., Methods: Fifteen patients with carotid artery stenosis ≥ 90% on the ipsilateral side and <50% on the contralateral side were enrolled into the study. PSV was assessed using colour-coded duplex sonography, CBF, CBV, MTT and TTP with perfusion computed tomography, cc-TQ and sas-TQ with near-infrared transillumination/backscattering sounding (NIR-T/BSS)., Results: Based on the ipsilateral/contralateral cc-TQ ratio after acetazolamide challenge two groups of patients were distinguished: the first group with a ratio ≥ 1 and the second with a ratio <1. In the second group increases in CBF and CBV after the acetazolamide test were significantly higher in both hemispheres (ipsilateral: +33.0% ± 8.1% vs. +15.3% ± 4.4% and +26.3% ± 6.6% vs. +14.3% ± 5.1%; contralateral: +26.8% ± 7.0% vs. +17.6% ± 5.6% and +20.0% ± 7.3% vs. +10.0% ± 3.7%, respectively), cc-TQ was significantly higher only on the ipsilateral side (+37.3% ± 9.3% vs. +26.6% ± 8.6%) and the decrease in sas-TQ was less pronounced on the ipsilateral side (-0.7% ± 1.5% vs. -10.2% ± 1.5%), in comparison with the first group. The changes in sas-TQ following the acetazolamide test were consistent with the changes in TTP., Conclusions: The ipsilateral/contralateral cc-TQ ratio following acetazolamide challenge may be used to distinguish patient groups characterized by different haemodynamic parameters. Further research on a larger group of patients is warranted.

Purpose: The purpose of the study was to: (1) evaluate the subarachnoid space (SAS) width and pial artery pulsation in both hemispheres, and (2) directly compare magnetic resonance imaging (MRI) to near-infrared transillumination/backscattering sounding (NIR-T/BSS) measurements of SAS width changes in healthy volunteers., Methods: The study was performed on three separate groups of volunteers, consisting in total of 62 subjects (33 women and 29 men) aged from 16 to 39 years. SAS width was assessed by MRI and NIR-T/BSS, and pial artery pulsation by NIR-T/BSS., Results: In NIR-T/BSS, the right frontal SAS was 9.1% wider than the left (p<0.01). The SAS was wider in men (p<0.01), while the pial artery pulsation was higher in women (p<0.01). Correlation and regression analysis of SAS width changes between the back- and abdominal-lying positions measured with MRI and NIRT-B/SS demonstrated high interdependence between both methods (r = 0.81, p<0.001)., Conclusions: NIR-T/BSS and MRI were comparable and gave equivalent modalities for the SAS width change measurements. The SAS width and pial artery pulsation results obtained with NIR-T/BSS are consistent with the MRI data in the literature related to sexual dimorphism and morphological asymmetries between the hemispheres. NIR-T/BSS is a potentially cheap and easy-to-use method for early screening in patients with brain tumours, increased intracranial pressures and other abnormalities. Further studies in patients with intracranial pathologies are warranted.

Purpose: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1) pial artery pulsation (cc-TQ); (2) cerebral blood flow velocity (CBFV); (3) peripheral blood pressure; and (4) possible relations between mentioned parameters., Methods: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ) were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS), CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO(2) was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT) and swayed to the back (initial) position., Results: In the first group (n = 10) during BOPT, sas-TQ and pulse pressure (PP) decreased (-17.6% and -17.9%, respectively) and CBFV increased (+35.0%), while cc-TQ did not change (+1.91%). In the second group, in the initial position (n = 22) cc-TQ and CBFV increased (106.6% and 20.1%, respectively), while sas-TQ and PP decreases were not statistically significant (-15.5% and -9.0%, respectively). End-tidal CO(2) remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = -0.74)., Conclusions: Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral disease.

The aim of this study was to assess the influence of the handgrip test (HGT) on: (1) pial artery pulsation (cc-TQ), (2) subarachnoid space (SAS) width (sas-TQ) and (3) the relationship between peripheral blood pressure (BP), heart rate (HR), cerebral blood flow velocity (CBFV), resistive index (RI), cc-TQ and sas-TQ. The study was performed on 29 healthy volunteers (11 men and 18 women) with a mean age of 29.3 ± SE 4.0. HGT was performed in the sitting position at 30% of maximal voluntary contraction. cc-TQ and sas-TQ were registered using near-infrared transillumination/backscattering sounding (NIR-T/BSS); BP and heart rate (HR) were measured using a Finapres monitor. CBFV and RI were recorded using a transcranial Doppler. A significant reduction in cc-TQ (-34.3%, P<0.0001) and sas-TQ (-12.9%, P<0.001) were observed, while mean arterial pressure and HR increased (+34.8%, P<0.0001 and +7.9%, P<0.0001, respectively). There was no significant change in CBFV (+1.0 percent) while RI increased (+12.0 percent, P<0.05). Correlation and regression analysis did not reveal any interdependencies between the investigated variables. HGT evoked a significant increase in pial artery resistance, with a simultaneous decrease in the width of the SAS. A decrease in pial artery compliance should be seen as protective mechanism against acute BP elevation, most likely mediated by sympathetic activation. NIR-T/BSS recordings allowed for non-invasive assessments of changes in pial artery compliance, and were consistent with data from the literature and physiological knowledge.

The objective was to assess changes in the width of the subarachnoid space (SAS) and amplitude of cerebrovascular pulsation (CVP) during acute elevation of intracranial pressure (ICP) using Near Infrared Transillumination/Back Scattering Sounding (NIR-T/BSS). Changes in the width of the SAS and amplitude of CVP were observed in rabbits during experimental ICP elevation induced by: (1) quick injections of saline into the subdural space of the spinal cord, and (2) distension of a surgical catheter balloon placed intracranially in the subdural space. The amplitude of CVP was also assessed during acute elevation of blood pressure in the intracranial portion of the internal carotid artery (ICA) induced by adrenaline. Each of the injections of saline caused a transient rise in the width of the SAS and amplitude of CVP. The amplitude of the increase in CVP was dependent on changes in blood pressure in the ICA (r=-0.82, P<0.01). Distension of the intracranial balloon resulted in elimination of the respiratory oscillations in the CVP and increased its systolic-diastolic amplitude. An increase in the amplitude of CVP was evoked by adrenaline without an increase in the carotid blood flow. We demonstrated that during elevation of ICP the amplitude of CVP depends on blood pressure rather than on blood flow in large cerebral vessels. Elimination of the respiratory oscillations by a minute ("sub-critical") ICP increase may be used as an early indicator of rising ICP. The direction of changes recorded using NIR-T/BSS was consistent with changes recorded using tensometric transducers.