Continuous positive airway pressure increases CSF flow and glymphatic transport.

Respiration can positively influence cerebrospinal fluid (CSF) flow in the brain, yet its effects on central nervous system (CNS) fluid homeostasis, including waste clearance function via glymphatic and meningeal lymphatic systems, remain unclear. Here, we investigated the effect of supporting respiratory function via continuous positive airway pressure (CPAP) on glymphatic-lymphatic function in spontaneously breathing anesthetized rodents. To do this, we used a systems approach combining engineering, MRI, computational fluid dynamics analysis, and physiological testing. We first designed a nasal CPAP device for use in the rat and demonstrated that it functioned similarly to clinical devices, as evidenced by its ability to open the upper airway, augment end-expiratory lung volume, and improve arterial oxygenation. We further showed that CPAP increased CSF flow speed at the skull base and augmented glymphatic transport regionally. The CPAP-induced augmented CSF flow speed was associated with an increase in intracranial pressure (ICP), including the ICP waveform pulse amplitude. We suggest that the augmented pulse amplitude with CPAP underlies the increase in CSF bulk flow and glymphatic transport. Our results provide insights into the functional crosstalk at the pulmonary-CSF interface and suggest that CPAP might have therapeutic benefit for sustaining glymphatic-lymphatic function.

Exogenous methyl jasmonate modulates antioxidant activities and delays pericarp browning in litchi.

Pericarp browning (PB) is a serious problem in harvested litchi and drastically affects consumer acceptability and marketability. Postharvest PB and subsequent decay in fruit are linked to reactive oxygen species (ROS) accumulation in tissues. Antioxidants neutralize or scavenge ROS and maintain the shelf-life of fruit, especially in non-climacteric ones such as litchi. This work was aimed to assess the effect of vacuum infiltrated methyl jasmonate (MeJA; 1 and 2 mM) on the quality of harvested litchi fruit (cv. Purbi) during ambient storage (28 °C, RH 70-75%). The exogenous MeJA infiltration (2 mM) significantly retained quality attributes of litchi fruit as evident by lowered PB, weight loss, disease occurrence, quinone, and ROS (H2O2 and O2 -) accumulation. Moreover, MeJA infiltrated fruit suppressed the activity of polyphenol oxidase and peroxidase resulting in higher anthocyanin, phenolics, antioxidant potential, phenylalanine ammonia lyase activity as well as membrane integrity throughout the storage. Control fruit showed an early quality deterioration marked by prominent PB and other biochemical degradative changes. Thus, exogenous MeJA infiltration (2 mM) could be suggested to increase the shelf life of litchi by four days under ambient conditions.

Choroid plexus tissue perfusion and blood to CSF barrier function in rats measured with continuous arterial spin labeling.

The choroid plexus (ChP) of the cerebral ventricles is a source of cerebrospinal fluid (CSF) production and also plays a key role in immune surveillance at the level of blood-to-CSF-barrier (BCSFB). In this study, we quantify ChP blood perfusion and BCSFB mediated water exchange from arterial blood into ventricular CSF using non-invasive continuous arterial spin labelling magnetic resonance imaging (CASL-MRI). Systemic administration of anti-diuretic hormone (vasopressin) was used to validate BCSFB water flow as a metric of choroidal CSF secretory function. To further investigate the coupling between ChP blood perfusion and BCSFB water flow, we characterized the effects of two anesthetic regimens known to have large-scale differential effects on cerebral blood flow. For quantification of ChP blood perfusion a multi-compartment perfusion model was employed, and we discovered that partial volume correction improved measurement accuracy. Vasopressin significantly reduced both ChP blood perfusion and BCSFB water flow. ChP blood perfusion was significantly higher with pure isoflurane anesthesia (2-2.5%) when compared to a balanced anesthesia with dexmedetomidine and low-dose isoflurane (1.0 %), and significant correlation between ChP blood perfusion and BCSFB water flow was observed, however there was no significant difference in BCSFB water flow. In summary, here we introduce a non-invasive, robust, and spatially resolved in vivo imaging platform to quantify ChP blood perfusion as well as BCSFB water flow which can be applied to study coupling of these two key parameters in future clinical translational studies.

Disparate volumetric fluid shifts across cerebral tissue compartments with two different anesthetics.

BACKGROUND: Large differences in glymphatic system transport-similar in magnitude to those of the sleep/wake cycle-have been observed during anesthesia with dexmedetomidine supplemented with low dose isoflurane (DEXM-I) in comparison to isoflurane (ISO). However, the biophysical and bioenergetic tissue status underlying glymphatic transport differences between anesthetics remains undefined. To further understand biophysical characteristics underlying these differences we investigated volume status across cerebral tissue compartments, water diffusivity, and T2* values in rats anesthetized with DEXM-I in comparison to ISO. METHODS: Using a crossover study design, a group of 12 Sprague Dawley female rats underwent repetitive magnetic resonance imaging (MRI) under ISO and DEXM-I. Physiological parameters were continuously measured. MRI included a proton density weighted (PDW) scan to investigate cerebrospinal fluid (CSF) and parenchymal volumetric changes, a multigradient echo scan (MGE) to calculate T2* maps as a measure of 'bioenergetics', and a diffusion scan to quantify the apparent diffusion coefficient (ADC). RESULTS: The heart rate was lower with DEXM-I in comparison to ISO, but all other physiological variables were similar across scans and groups. The PDW images revealed a 1% parenchymal volume increase with ISO compared to DEXM-I comprising multiple focal tissue areas scattered across the forebrain. In contrast, with DEXM-I the CSF compartment was enlarged by ~ 6% in comparison to ISO at the level of the basal cisterns and peri-arterial conduits which are main CSF influx routes for glymphatic transport. The T2* maps showed brain-wide increases in T2* in ISO compared to DEXM-I rats. Diffusion-weighted images yielded no significant differences in ADCs across the two anesthesia groups. CONCLUSIONS: We demonstrated CSF volume expansion with DEXM-I (in comparison to ISO) and parenchymal (GM) expansion with ISO (in comparison to DEXM-I), which may explain the differences in glymphatic transport. The T2* changes in ISO are suggestive of an increased bioenergetic state associated with excess cellular firing/bursting when compared to DEXM-I.

Glymphatic Cerebrospinal Fluid and Solute Transport Quantified by MRI and PET Imaging.

Over the past decade there has been an enormous progress in our understanding of fluid and solute transport in the central nervous system (CNS). This is due to a number of factors, including important developments in whole brain imaging technology and computational fluid dynamics analysis employed for the elucidation of glymphatic transport function in the live animal and human brain. In this paper, we review the technical aspects of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in combination with administration of Gd-based tracers into the cerebrospinal fluid (CSF) for tracking glymphatic solute and fluid transport in the CNS as well as lymphatic drainage. Used in conjunction with advanced computational processing methods including optimal mass transport analysis, one gains new insights into the biophysical forces governing solute transport in the CNS which leads to intriguing new research directions. Considering drainage pathways, we review the novel T1 mapping technique for quantifying glymphatic transport and cervical lymph node drainage concurrently in the same subject. We provide an overview of knowledge gleaned from DCE-MRI studies of glymphatic transport and meningeal lymphatic drainage. Finally, we introduce positron emission tomography (PET) and CSF administration of radiotracers as an alternative method to explore other pharmacokinetic aspects of CSF transport into brain parenchyma as well as efflux pathways.

Role of maturity stages and modified-atmosphere packaging on the quality attributes of cornelian cherry fruits (Cornus mas L.) throughout shelf life.

BACKGROUND: A study was conducted to determine the effects of modified-atmosphere packaging (MAP) treatments on fruit quality attributes and bioactive compounds of cornelian cherry fruits (Cornus mas L.) harvested at two different maturity stages - maturity (M): M-1, skin red color <10%; M-2, skin red color >90% - throughout the shelf life. Fruits were stored at 0 ± 0.5 °C and 90 ± 5% relative humidity (RH) for 30 days, and then kept at 22 ± 0.5 °C and 80 ± 5% RH over 3 days for shelf life. RESULTS: In the measurements performed at harvest, MS-2 fruits had significantly greater respiration rate, soluble solids content, acidity, anthocyanin, flavonoids, and phenolics and significantly lower ethylene productions, firmness, L* , chroma, and hue angle values than MS-1 fruits. In the last measurement period, MAP-treated fruits had significantly greater firmness, total flavonoids, and total phenolics and significantly lower respiration rates, ethylene productions, and decay rates than the untreated fruits. While color parameters of MS-2 fruits were significantly lower than the color values of MS-1 fruits, they had greater vitamin C and anthocyanin contents. CONCLUSION: It was concluded that the cornelian cherry fruits harvested at MS-2 stage of maturity and preserved in MAP better maintained quality attributes throughout their shelf life. © 2018 Society of Chemical Industry.

Effect of pre-harvest methyl jasmonate treatments on ethylene production, water-soluble phenolic compounds and fruit quality of Japanese plums.

BACKGROUND: The effects of pre-harvest methyl jasmonate (MJ) treatments on ethylene production, respiration rate, bioactive compounds and physico-chemical parameters of plum fruits (Prunus salicina Lindell cv. 'Fortune' and 'Friar') were investigated. Whole trees were sprayed once with an aqueous solution containing MJ (0, 1120 and 2240 mg L(-1)) 2 weeks before the anticipated commercial harvest for each cultivar. RESULTS: In both plum cultivars, 1120 mg L(-1) MJ significantly increased hue angle of fruits. The fruit mass and geometric mean diameter were lower in MJ treatments while flesh firmness was higher, except at initial harvest date. Soluble solids concentration increased and titratable acidity decreased with MJ treatments. MJ-treated fruits exhibited higher levels of ethylene production and respiration rate. MJ was more effective in increasing water-soluble antioxidant activity, water-soluble phenolics and individual phenolics. Chlorogenic acid, caffeic acid, rutin, ferulic acid, naringenin and kaempferol contents significantly increased with 2240 mg L(-1) MJ. CONCLUSIONS: This study revealed that pre-harvest MJ treatments were effective in delaying softening of late-harvested fruits and increasing bioactive compounds of plum fruits.

The effects of pre-harvest application of aminoethoxyvinylglycine on the bioactive compounds and fruit quality of 'Fortune' plum variety during cold storage.

The effects of pre-harvest aminoethoxyvinylglycine treatments on fruit quality parameters and bioactive compounds of 'Fortune' plum during cold storage were investigated. Two different aminoethoxyvinylglycine doses were applied to plum trees two weeks prior to the estimated harvest date, and harvested fruit samples were kept in cold storage at 0 (°)C temperature and with 90 ± 5% relative humidity for 4 weeks. Lightness (L*) and hue angle values decreased in all treatments during cold storage. Weight loss (%) was significantly decreased (p < 0.05) with 100 mg/L aminoethoxyvinylglycine treatment at the end of the storage. Fruit firmness at the end of the storage was significantly increased with aminoethoxyvinylglycine treatments. Total phenolics and total antioxidant activity were increased with aminoethoxyvinylglycine treatments till the 21st day of storage and decreased by the 28th day. Total phenolics and total antioxidant activity were significantly decreased (p < 0.05) with the 200 mg/L aminoethoxyvinylglycine treatment at the end of storage. Rutin was significantly decreased with 100 mg/L aminoethoxyvinylglycine treatment at the end of cold storage.