scholarly journals A Systematic Search and Mapping Review of Studies on Intracerebral Microdialysis of Amino Acids, and Systematized Review of Studies on Circadian Rhythms

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Cathalijn H. C. Leenaars ◽  
Jennifer Freymann ◽  
Koen Jakobs ◽  
Julia M. L. Menon ◽  
Thomas J. Van Ee ◽  
...  
Keyword(s):  
Amino Acids ◽  
Circadian Rhythms ◽  
Systematic Search ◽  
Intracerebral Microdialysis ◽  
Systematized Review ◽  
Mapping Review

scholarly journals Intracerebral Microdialysis of Extracellular Amino Acids in the Human Epileptic Focus

1992 ◽  
Vol 12 (5) ◽  
pp. 873-876 ◽  
Author(s):  
Elisabeth Ronne-Engström ◽  
Lars Hillered ◽  
Roland Flink ◽  
BO Spännare ◽  
Urban Ungerstedt ◽  
...  
Keyword(s):  
Amino Acids ◽  
Brain Damage ◽  
Epilepsy Surgery ◽  
Seizure Activity ◽  
Intractable Epilepsy ◽  
The Other ◽  
Epileptic Focus ◽  
Intracerebral Microdialysis ◽  
Focal Seizures

Extracellular levels of aspartate (ASP), glutamate (GLU), serine (SER), asparagine (ASN), glycine (GLY), threonine (THR), arginine (ARG), alanine (ALA), taurine (TAU), tyrosine (TYR), phenylalanine (PHE), isoleucine (ILEU), and leucine (LEU) were monitored by using intracerebral microdialysis in seven patients with medically intractable epilepsy, undergoing epilepsy surgery. In association with focal seizures, dramatic increases of the extracellular ASP, GLU, GLY, and SER concentrations were observed. The other amino acids analyzed, including TAU, showed small changes. The results support the hypothesis that ASP, GLU, GLY, and possibly SER, play an important role in the mechanism of seizure activity and seizure-related brain damage in the human epileptic focus.

scholarly journals Chroniques génomiques

2020 ◽  
Vol 36 (6-7) ◽  
pp. 675-677
Author(s):  
Bertrand Jordan
Keyword(s):  
Amino Acids ◽  
Functional Significance ◽  
Open Reading Frames ◽  
Systematic Search ◽  
Biological Processes ◽  
Coding Sequence ◽  
Small Proteins ◽  
Human Dna ◽  
Small Orfs ◽  
Reading Frames

A systematic search for non-conventional open reading frames in human DNA reveals a large number of small ORFs encoding peptides generally smaller than 100 amino-acids. These ORFs are transcribed and translated into small proteins, which are demonstrated to have functional significance by bulk CRISPR inactivation. Evidence is also found for bicistronic mRNAs including such a small ORF upstream of a canonical coding sequence. These findings add a new facet to our understanding of biological processes.

Neurochemical monitoring using intracerebral microdialysis in patients with subarachnoid hemorrhage

1996 ◽  
Vol 84 (4) ◽  
pp. 606-616 ◽  
Author(s):  
Lennart Persson ◽  
Johann Valtysson ◽  
Per Enblad ◽  
Per-Erik Wärme ◽  
Kristina Cesarini ◽  
...  
Keyword(s):  
Amino Acids ◽  
Subarachnoid Hemorrhage ◽  
Energy Metabolism ◽  
Human Brain ◽  
Excitatory Amino Acids ◽  
Extracellular Fluid ◽  
Brain Energy Metabolism ◽  
Intracerebral Microdialysis ◽  
Brain Energy ◽  
Pyruvate Ratio

✓ The authors have developed a method for routine monitoring of disturbances in brain energy metabolism and extracellular levels of excitatory amino acids using intracerebral microdialysis in 10 patients with subarachnoid hemorrhage. Microdialysis was conducted for periods ranging from 6 to 11 days after ictus. Altogether, 16,054 chemical analyses from 1647 dialysate samples were performed. Concentrations of the energy-related substances lactate, pyruvate, glucose, and hypoxanthine were measured, and the lactate/pyruvate ratio was calculated. The excitatory amino acids glutamate and aspartate were measured. The microdialysis data were matched with computerized tomography findings, clinical course, and outcome. The results support the concepts that microdialysis is a promising tool for chemical monitoring of the human brain and that extracellular fluid levels of lactate, lactate/pyruvate ratio, glucose, hypoxanthine, and glutamate are useful markers of disturbances in brain energy metabolism in neurointensive care patients. These results have generated a working hypothesis that the pattern of these extracellular markers may help differentiate between various causes of energy perturbations, such as hypoxia and different degrees of ischemia. The correlation between the dialysate levels of excitatory amino acids and outcome supports the concept of glutamate receptor overactivation in acute human brain injury.

Multiple Interstitial Substances Measured by Microdialysis in Patients with Subarachnoid Hemorrhage

Neurosurgery ◽  
2000 ◽  
Vol 47 (5) ◽  
pp. 1106-1116 ◽  
Author(s):  
Frank Staub ◽  
Rudolf Graf ◽  
Paula Gabel ◽  
Matthias Köchling ◽  
Norfrid Klug ◽  
...  
Keyword(s):  
Amino Acids ◽  
Subarachnoid Hemorrhage ◽  
Brain Damage ◽  
Glasgow Outcome Scale ◽  
Excitatory Amino Acids ◽  
Intracerebral Microdialysis ◽  
Secondary Brain Damage ◽  
Scale Scores ◽  
Poor Outcomes ◽  
Temporal Profiles

Abstract OBJECTIVE Intracerebral microdialysis is a tool to monitor metabolic disturbances in the brains of patients with severe head injuries or subarachnoid hemorrhage (SAH). In the search for putative indicators of primary and secondary brain damage, we measured multiple metabolites in the dialysates of patients with SAH, to elucidate their significance for the outcomes of the patients as well as their temporal profiles of liberation after the insult. METHODS Microdialysis probes were placed, with a ventriculostomy catheter for drainage of cerebrospinal fluid, into a frontal lobe of 10 patients with aneurysmal SAH, for 4.6 ± 0.5 days. Amino acids, metabolites of glycolysis, purines, catecholamines, and nitric oxide oxidation byproducts were measured by high-performance liquid chromatography. Spearman's correlation coefficient and Student's t test were used to compare the levels of the metabolites with the outcomes of the patients, as assessed using the Glasgow Outcome Scale, 3 months after the ictus. RESULTS For patients with unfavorable outcomes (Glasgow Outcome Scale scores of 1–3), which were primarily associated with the development of large infarctions, dialysate levels of excitatory amino acids increased up to 30-fold, those of lactate up to 10-fold, and those of nitrite up to 5-fold, compared with normal levels observed for patients with favorable outcomes (Glasgow Outcome Scale scores of 4 or 5). When average peak concentrations in the dialysates of patients with favorable and unfavorable outcomes were compared, significantly higher levels of excitatory amino acids, taurine, lactate, and nitrite, but not of purines and catecholamines, were observed for those with poor outcomes (P < 0.05). With respect to the temporal profiles of the average metabolite concentrations, the significantly increased levels of amino acids observed for patients with poor outcomes followed a biphasic course, with maximal concentrations on the first and second days or the seventh day after the insult (P < 0.01). CONCLUSION These data confirm the usefulness of excitatory amino acids and lactate as major parameters for neurochemical monitoring for patients threatened by acute cerebral disorders. Other substances, such as taurine and nitrite, were also demonstrated to be potentially predictive. Release of these substances into the extracellular fluid of the brain might be particularly relevant for the development of secondary brain damage after SAH, e.g., infarction or brain swelling.

scholarly journals Extracellular Antioxidants and Amino Acids in the Cortex of the Rat: Monitoring by Microdialysis of Early Ischemic Changes

1992 ◽  
Vol 12 (1) ◽  
pp. 96-102 ◽  
Author(s):  
H. Landolt ◽  
T. W. Lutz ◽  
H. Langemann ◽  
D. Stäuble ◽  
A. Mendelowitsch ◽  
...  
Keyword(s):  
Amino Acids ◽  
Ascorbic Acid ◽  
Uric Acid ◽  
Artery Occlusion ◽  
Left Middle Cerebral Artery ◽  
Sham Operation ◽  
Intracerebral Microdialysis ◽  
Microdialysis Probe ◽  
Cerebral Artery Occlusion ◽  
Ischemic Events

Extracellular concentrations of ascorbic acid, glutathione, cysteine, uric acid, tyrosine, and tryptophan were monitored using intracerebral microdialysis in the left frontoparietal cortex of spontaneous hypertensive rats before, and for 3 h after, either focal ischemia [left middle cerebral artery occlusion (MCAO)] or sham operation. The size of the ischemic area and the position of the microdialysis probe were checked using the enzyme histotopochemical acid phosphatase reaction. The probe was always located in the cortex inside the stained area. Ascorbic acid levels rose immediately after MCAO and remained at about 12-fold for 3 h. There was a transient release of glutathione during 1–1.5 h. Uric acid concentrations were also increased but the differences did not reach significance. The levels of the amino acids tyrosine and tryptophan increased steadily after MCAO. The increases in cysteine were variable but significant. In some experiments, the pH of the dialysate was measured online. The parameters ascorbic acid, glutathione, cysteine, and pH are suitable for the early detection of cortical ischemic events by microdialysis.

A Mapping Review of Physical Activity Recordings Derived From Smartphone Accelerometers

2020 ◽  
Vol 17 (11) ◽  
pp. 1184-1192
Author(s):  
Jarle Stålesen ◽  
Thomas Westergren ◽  
Bjørge Herman Hansen ◽  
Sveinung Berntsen
Keyword(s):  
Physical Activity ◽  
Indirect Calorimetry ◽  
Systematic Search ◽  
Embedded Sensors ◽  
Measurement Properties ◽  
Accuracy Of Measurements ◽  
Mapping Review ◽  
Large Heterogeneity ◽  
Research Grade

Background: Smartphones with embedded sensors, such as accelerometers, are promising tools for assessing physical activity (PA), provided they can produce valid and reliable indices. The authors aimed to summarize studies on the PA measurement properties of smartphone accelerometers compared with research-grade PA monitors or other objective methods across the intensity spectrum, and to report the effects of different smartphone placements on the accuracy of measurements. Methods: A systematic search was conducted on July 1, 2019 in PubMed, Embase, SPORTDiscus, and Scopus, followed by screening. Results: Nine studies were included, showing moderate-to-good agreements between PA indices derived from smartphone accelerometers and research-grade PA monitors and/or indirect calorimetry. Three studies investigated measurement properties across smartphone placements, with small differences. Large heterogeneity across studies hampered further comparisons. Conclusions: Despite moderate-to-good agreements between PA indices derived from smartphone accelerometers and research-grade PA monitors and/or indirect calorimetry, the validity of smartphone monitoring is currently challenged by poor intermonitor reliability between smartphone brands/versions, heterogeneity in protocols used for validation, the sparsity of studies, and the need to address the effects of smartphone placement.

Chemical monitoring of neurosurgical intensive care patients using intracerebral microdialysis

1992 ◽  
Vol 76 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Lennart Persson ◽  
Lars Hillered
Keyword(s):  
Amino Acids ◽  
Intensive Care ◽  
Extracellular Fluid ◽  
Therapeutic Interventions ◽  
Intracerebral Microdialysis ◽  
Content Type ◽  
Clinical Events ◽  
Neurosurgical Patients ◽  
Neurosurgical Intensive Care

✓ The authors have used intracerebral microdialysis to develop a method for routine monitoring of disturbances in brain energy metabolism in patients in the neurosurgical intensive care unit. Microdialysis was conducted for periods ranging from 2.3 to 8.3 days in four patients (three with severe head injuries and one with severe subarachnoid hemorrhage). Altogether, 4447 chemical analyses from 587 dialysis samples were carried out. Concentrations of the energy-related metabolites lactate, pyruvate, and hypoxanthine were measured, and the lactate:pyruvate ratio was calculated. In addition, the amino acids glutamate, aspartate, taurine, glutamine, asparagine, and glycine were measured in one patient. The microdialysis data were matched with various clinical events, including intracranial hypertension and therapeutic interventions such as initiation or withdrawal of barbiturates and cerebrospinal fluid drainage. The present study shows that microdialysis can be used for long-term measurement of extracellular fluid (ECF) energy-related metabolites and amino acids in the frontal cortex of neurosurgical patients in a clinical setting. Fluctuations of the measured ECF energy-related substances corresponded to various clinical events presumably involving hypoxia/ischemia. The authors found a 25-fold increase in ECF glutamate, aspartate, and taurine under conditions of energy perturbation, as indicated by high levels of the lactate:pyruvate ratio, lactate, and hypoxanthine. The use of long-term intracerebral microdialysis in patients opens a new field of clinical research, with many possibilities for improving insight into intracranial dynamics in acute cerebral conditions.

scholarly journals Dynamics of Extracellular Metabolites in the Striatum after Middle Cerebral Artery Occlusion in the Rat Monitored by Intracerebral Microdialysis

1989 ◽  
Vol 9 (5) ◽  
pp. 607-616 ◽  
Author(s):  
L. Hillered ◽  
A. Hallström ◽  
S. Segersvärd ◽  
L. Persson ◽  
U. Ungerstedt
Keyword(s):  
Amino Acids ◽  
Cerebral Ischemia ◽  
Middle Cerebral Artery ◽  
Middle Cerebral Artery Occlusion ◽  
Cerebral Artery ◽  
Focal Cerebral Ischemia ◽  
Artery Occlusion ◽  
Intracerebral Microdialysis ◽  
Dopamine Metabolites ◽  
Cerebral Artery Occlusion

The aim of this study was to measure changes in the extracellular fluid (ECF) concentration of lactate, pyruvate, purines, amino acids, dopamine, and dopamine metabolites in the striatum of rats subjected to focal cerebral ischemia, using intracerebral microdialysis as the sampling technique. Microdialysis probes were inserted into the lateral part of the caudate-putamen bilaterally 2 h before the experiment. Ischemia was induced by permanent middle cerebral artery occlusion (MCAO) on the left side. Microdialysis samples were analyzed by high performance liquid chromatography. Following MCAO, the concentration of lactate, adenosine, inosine, and hypoxanthine rose markedly in the ECF on the occluded side, while there was no significant change in pyruvate. These changes were accompanied by dramatically elevated levels of aspartate, glutamate, taurine, γ-aminobutyric acid, and dopamine. There was also a marked increase in alanine/tyrosine, while minor or no changes occurred with other amino acids. Concomitantly, the ECF level of the dopamine metabolites 3,4–dihydroxyphenylacetate and homovanillic acid decreased. There was no significant increase in any of the metabolites measured on the right, nonoccluded side. In relation to the concept of excitotoxicity in brain ischemia, it is concluded that during the acute stage of focal cerebral ischemia, the ECF is flooded with both potentially harmful (e.g., aspartate, glutamate, and DA) and protective (e.g., taurine, GABA, and adenosine) agents. The relative importance of these events for the development of cell death in the ischemic penumbra needs to be elucidated. In addition, lactate, inosine, and hypoxanthine, measured in the ECF by intracerebral microdialysis, may prove to have diagnostic and/or prognostic value in neurometabolic monitoring of the ischemic brain.

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