This paper reconsiders the role of mitochondria in aging and in Parkinson's Disease (PD). The most important risk factor for PD is aging. Alterations in mitochondrial activity are typical of aging. ...Mitochondrial aging is characterized by decreased oxidative phosphorylation, proteasome activity decrease, altered autophagy, and mitochondrial dysfunction. Beyond declined oxidative phosphorylation, mitochondrial dysfunction consists of a decline of beta-oxidation as well as of the Krebs cycle. Not inherited mitochondrial DNA (mtDNA) mutations are acquired over time and parallel the decrease in oxidative phosphorylation. Many of these mitochondrial alterations are also found in the PD brain specifically in the substantia nigra (SN). mtDNA deletions and development of respiratory chain deficiency in SN neurons of aged individuals as well as of individuals with PD converge towards a shared pathway, which leads to neuronal dysfunction and death. Finally, several nuclear genes that are mutated in hereditary PD are usually implicated in mitochondrial functioning to a various extent and their mutation may cause mitochondrial impairment. In conclusion, a tight link exists between mitochondria, aging, and PD.
Temperature plays a fundamental role for the proper functioning of the brain. However, there are only fragmentary data on brain temperature (T(br)) and its regulation under different physiological ...conditions.
We studied T(br) in the visual cortex of 20 normal subjects serially with a wide temporal window under different states including rest, activation and recovery by a visual stimulation-Magnetic Resonance Spectroscopy Thermometry combined approach. We also studied T(br) in a control region, the centrum semiovale, under the same conditions.
Visual cortex mean baseline T(br) was higher than mean body temperature (37.38 vs 36.60, P<0.001). During activation Tbr remained unchanged at first and then showed a small decrease (-0.20 C°) around the baseline value. After the end of activation T(br) increased consistently (+0.60 C°) and then returned to baseline values after some minutes. Centrum semiovale T(br) remained unchanged through rest, visual stimulation and recovery.
These findings have several implications, among them that neuronal firing itself is not a major source of heat release in the brain and that there is an aftermath of brain activation that lasts minutes before returning to baseline conditions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Parkinson's disease (PD) is associated with brain mitochondrial dysfunction. High-energy phosphates (HEPs), which rely on mitochondrial functioning, may be considered potential biomarkers for PD. ...Phosphorus magnetic resonance spectroscopy (
P-MRS) is a suitable tool to explore in vivo cerebral energetics. We considered 10
P-MRS studies in order to highlight the main findings about brain energetic compounds in patients affected by idiopathic PD and genetic PD. The studies investigated several brain areas such as frontal lobes, occipital lobes, temporoparietal cortex, visual cortex, midbrain, and basal ganglia. Resting-state studies reported contrasting results showing decreased as well as normal or increased HEPs levels in PD patients. Functional studies revealed abnormal PCr + βATP levels in PD subjects during the recovery phase and abnormal values at rest, during activation and recovery in one PD subject with PINK1 gene mutation suggesting that mitochondrial machinery is more impaired in PD patients with PINK1 gene mutation. PD is characterized by energetics impairment both in idiopathic PD as well as in genetic PD, suggesting that mitochondrial dysfunction underlies the disease. Studies are still sparse and sometimes contrasting, maybe due to different methodological approaches. Further studies are needed to better assess the role of mitochondria in the PD development.
The maintenance of a stable temperature is of the utmost importance for the proper functioning of the brain. Brain temperature is tightly linked to mitochondrial energetics. Although Parkinson's ...disease is characterized by mitochondrial dysfunction, no data are available on brain temperature. We measured the temperature in the visual cortex and in the centrum semiovale at rest by proton magnetic resonance spectroscopy in patients with Parkinson's disease and in age-matched and sex-matched control participants. We report evidence of increased temperature in the visual cortex and, to a minor extent, in the centrum semiovale of patients with Parkinson's disease. The increase in brain temperature is best explained by an energy loss along the oxidative phosphorylation/respiratory chain.
Purpose: To develop a method for the non‐invasive detection and quantification of eyelid movements during spontaneous blinking.
Methods: Spontaneous eyelid movements were monitored using an ...optoelectronic motion analyzer with passive markers in a younger group aged 20–30 years (13 men, 12 women) and in an older group over 50 years (10 men and nine women). Blink rate, eyelid displacement as a percentage of maximum excursion, and maximum eyelid velocity in closing and opening were calculated.
Results: Spontaneous blink rate was significantly larger in women than in men (19 vs 11 blinks per minute); older women blinked more frequently than younger women. On average, young men closed the eyes completely (or almost completely) 44% of times, whereas the eyelid closure of young and older women was more frequently between 51 and 75% of the maximum excursion. Older men rarely closed completely and showed a similar frequency of blinks with up to 25%, 50% and 75% of maximum excursion. During eyelid closure and opening, the maximum velocity reduced with age: older subjects moved their eyelids approximately 80–70% slower than younger subjects. In all subjects, closing was performed 40–47% faster than opening; women moved faster than men. Eyelid displacement was greater in young than in older subjects.
Conclusions: The method used in this study allowed the non‐invasive detection of eyelid movements during spontaneous blinking, providing a set of descriptive and kinematic data. The method could also be used to assess blink characteristics in patients with movement disorders, without invasive or time‐consuming procedures.
Posterior Cortical Atrophy (PCA) is a neurodegenerative disease characterized by a progressive decline in selective cognitive functions anatomically referred to occipital, parietal and temporal brain ...regions, whose diagnosis is rather challenging for clinicians. The aim of this study was to assess, using quantitative Magnetic Resonance Imaging techniques, the pattern of regional grey matter loss and metabolism in individuals with PCA to improve pathophysiological comprehension and diagnostic confidence.
We enrolled 5 patients with PCA and 5 matched controls who all underwent magnetic resonance imaging (MRI) and spectroscopy (MRS). Patients also underwent neuropsychological and cerebrospinal fluid (CSF) assessments. MRI data were used for unbiased assessment of regional grey matter loss in PCA patients compared to controls. MRS data were obtained from a set of brain regions, including the occipital lobe and the centrum semiovale bilaterally, and the posterior and anterior cingulate.
VBM analysis documented the presence of focal brain atrophy in the occipital lobes and in the posterior parietal and temporal lobes bilaterally but more pronounced on the right hemisphere. MRS revealed, in the occipital lobes and in the posterior cingulate cortex of PCA patients, reduced levels of N-Acetyl Aspartate (NAA, a marker of neurodegeneration) and increased levels of Myo-Inositol (Ins, a glial marker), with no hemispheric lateralization.
The bilateral but asymmetric pattern of regional grey matter loss is consistent with patients' clinical and neuropsychological features and with previous literature. The MRS findings reveal different stages of neurodegeneration (neuronal loss; gliosis), which coexist and likely precede the occurrence of brain tissue loss, and might represent early biomarkers. In conclusion, this study indicates the potential usefulness of a multi-parametric MRI approach for an early diagnosis and staging of patients with PCA.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In vivo brain metabolomics in Parkinson's disease is still in its infancy. This chapter will review brain metabolomics in the human brain as studied noninvasively by magnetic resonance spectroscopy. ...Although preliminary, the results shed some light on the pathophysiology of Parkinson's disease.
Objective The objective of the study was to determine the feasibility of detecting fetal brain lactate, a marker of fetal metabolic acidemia, using a noninvasive technique, proton magnetic resonance ...spectroscopy (1 H MRS), in intrauterine growth-restricted (IUGR) fetuses. Study Design In vivo human fetal brain lactate detection was determined by1 H MRS in 5 fetuses with IUGR. Oxygenation and acid-base balance data were obtained at birth. Results1 H MRS analysis showed the presence of a lactate peak in the brain of the most severely affected IUGR fetus, with abnormal umbilical artery Doppler and fetal heart rate tracing. This finding was consistent with the low oxygen content and high lactic acid concentration observed in umbilical blood obtained at delivery. Conclusion1 H MRS allows the noninvasive detection of cerebral lactate in IUGR fetuses. Lactate detected by1 H MRS may represent a possible marker of in utero cerebral injury or underperfusion.
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