Search results for "PNI"
showing 10 items of 159 documents
TISSUE OXYGENATION AND TISSUE METABOLISM IN THE BRAIN CORTEX DURING PRONOUNCED ARTERIAL HYPOCAPNIA
1981
Publisher Summary This chapter describes the tissue oxygenation and tissue metabolism in the brain cortex during pronounced arterial hypocapnia. Acute arterial hypocapnia induced by hyperventilation leads to typical reactions in the circulation and the metabolism of the brain tissue. With a lowering of arterial CO2 tension, the cerebro-vascular resistance (CVR) increases resulting in a decrease of cerebral blood flow. The changes in CVR are a consequence of decreasing hydrogen ion and potassium ion concentrations in the perivascular space of the brain arterioles. The corresponding changes in the brain metabolism are characterized by elevated concentrations of lactate and pyruvate and an inc…
Human corticotropin-releasing hormone and thyrotropin-releasing hormone modulate the hypercapnic ventilatory response in humans
1996
Human corticotropin-releasing hormone (hCRH) and thyrotropin-releasing hormone (TRH) are known to stimulate ventilation after i.v. administration in humans. In a placebo-controlled, single-blind study we aimed to clarify if both peptides act by altering central chemosensitivity. Two subsequent CO2-rebreathing tests were performed in healthy young volunteers. During the first test 0.9% NaCl was given i.v.; during the second test 200 micrograms of hCRH (n = 12) or 400 micrograms of TRH (n = 6) was administered i.v. Nine subjects received 0.9% NaCl i.v. during both rebreathing manoeuvres. The CO2-response curves for the two tests were compared within the same subject. In the hCRH group a marke…
Effects of severe arterial hypocapnia on regional blood flow regulation, tissuePO2 and metabolism in the brain cortex of cats
1981
The effect of a stepwise decrease in PaCO2 from 3.9-1.6 kPa on rCBF, rCMRO2, tissue PO2 and concentrations of glucose, lactate, pyruvate, ATP, ADP, AMP and phosphocreatine in the brain cortex was studied in cats lightly anaesthetized with sodium pentobarbital. 1. Moderate lowering of PaCO2 to 2.5 kPa induced in all animals a homogeneous decrease of rCBF in corresponding areas of the right and left hemisphere. Mean rCBF fell from 129.2 to 103.1 ml X 100 g-1 X min-1, while rCMRO2 remained unchanged (12.7-12.9 ml X 100 g-1 X min-1). The tissue PO2 frequency histograms showed a shift to lower values without indicating the presence of brain tissue hypoxia. 2. Severe arterial hypocapnia (PaCO2 = …
The effects of arterial CO2 on the injured brain: Two faces of the same coin
2021
Serum levels of carbon dioxide (CO2) closely regulate cerebral blood flow (CBF) and actively participate in different aspects of brain physiology such as hemodynamics, oxygenation, and metabolism. Fluctuations in the partial pressure of arterial CO2 (PaCO2) modify the aforementioned variables, and at the same time influence physiologic parameters in organs such as the lungs, heart, kidneys, and the gastrointestinal tract. In general, during acute brain injury (ABI), maintaining normal PaCO2 is the target to be achieved. Both hypercapnia and hypocapnia may comprise secondary insults and should be avoided during ABI. The risks of hypocapnia mostly outweigh the potential benefits. Therefore, i…
Vasomotor reactivity in dementia of alzheimer type
1994
The objective of this study was to examine the cerebral blood flow and the vasomotor function of CO2-responsive intracerebral vessels in Alzheimer's disease. Patients met DSM-III-R criteria for dementia of Alzheimer type and had neither symptoms nor signs of cardiovascular or cerebrovascular disease. Blood flow velocities in both middle cerebral arteries (MCA) were recorded using transcranial Doppler sonography during hypercapnia, normocapnia and hypocapnia. Several psychometric tests were performed. Patients' age, disease duration and severity of dementia did not correlate with vasomotor reactivity. Exploratory analysis revealed that mean flow velocities under hypercapnia correlated with s…
Is a Mask That Covers the Mouth and Nose Free from Undesirable Side Effects in Everyday Use and Free of Potential Hazards?
2021
International journal of environmental research and public health : IJERPH 18(8), 4344 (2021). doi:10.3390/ijerph18084344
2019
Since little is known concerning the psychological, cognitive, and neurophysiological factors that are involved in and important for phases of prolonged breath-holding (pBH) in freedivers, the present study uses electroencephalography (EEG) to investigate event-related neurocognitive markers during pBH of experienced freedivers that regularly train pBH. The purpose was to determine whether the well-known neurophysiological modulations elicited by hypoxic and hypercapnic conditions can also be detected during pBH induced hypoxic hypercapnia. Ten experienced free-divers (all male, aged 35.10 ± 7.89 years) were asked to hold their breath twice for 4 min per instance. During the first pBH, a ch…
Krāpšanas gadījumu atklāšana un prevencija mobilo sakaru tīklos
2015
Mobilo sakaru operatori krāpniecības dēļ ik gadu zaudē ievērojamus līdzekļus, tāpēc tiek meklēti ar vien efektīvāki līdzekļi zaudējumu mazināšanai. Šobrīd ikdienas praksē ir zināmi vairāki krāpšanas veidi, katram no tiem tiek pielietotas dažādas metodes, lai tos atklātu un novērstu. Tomēr ar katru dienu parādās arī jauni paņēmieni, kuri apiet jau esošās aizsardzības metodes un pieņemtos likumus. Maģistra darbā tiek apskatīta teorētiskā puse, kas sevī ietver iepazīšanos ar mobilo sakaru vispārīgajiem darbības principiem un operatoru darbības specifiku. Tālāk detalizētāki tiek veikta vairāku šobrīd zināmo krāpniecības veidu analīze, apskatot gan esošos atklāšanas paņēmienus, gan ieskicējot ie…
Na tropach tajemniczego M.K
2017
The article titled Artists and Philistines, published in 1897 in the “Kurier Niedzielny”, a moderated weekly with a compromising orientation (publisher: Maria Chełmońska, editors: Ludomir Grendyszyński), is an example of a voice about artist-society relationship typical of the end of the century. The author takes an indirect position: he criticizes both the anti-art social climate and the artists themselves, who wrongly accuse a society solidly fulfilling its duties of being “philistine”. The peculiarities of the script, the cryptic code and the ambiguous attitude of the journalist, as well as a number of clues in literary and artistic life, constitute a set of data that hypothetically prop…
Tapaustutkimus venäläisestä DPNI-äärioikeistoliikkeestä yhteiskunnallisen kontekstin tuotteena ja kansallisen identiteetin rakentajana
2009
Tämä pro gradu-tutkielma on tapaustutkimus venäläisestä äärioikeistoliikkeestä, joka tunnetaan nimellä DPNI – Laittoman maahanmuuton vastainen liike. Tutkimuksella on kaksi tavoitetta. Ensinnäkin olen pyrkinyt rakentamaan liikkeestä yksityiskohtaista ja syvällistä yleiskuvaa vuodesta 2005 vuoden 2009 kevääseen ulottuvalta ajanjaksolta. Vaikka kyse on yksittäisen liikkeen tutkimisesta, työni rakentaa osaltaan myös esimerkinomaista kuvausta laajemmasta ilmiöstä; rasismin ja äärioikeistolaisuuden esiintymisestä Venäjällä ja niiden kytkeytymisestä identiteettipolitiikkaan. Toisena tavoitteena onkin ollut analysoida DPNI:n verkkosivujen tekstejä siitä näkökulmasta, miten ja millaista kansallista…