| 61. |
- Nguyen, Tho D. K., et al.
(författare)
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Visualization of Partial Exocytotic Content Release and Chemical Transport into Nanovesicles in Cells
- 2022
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Ingår i: Acs Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:3, s. 4831-4842
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Tidskriftsartikel (refereegranskat)abstract
- For decades, "all-or-none"and "kiss-and-run"were thought to be the only major exocytotic release modes in cell-to-cell communication, while the significance of partial release has not yet been widely recognized and accepted owing to the lack of direct evidence for exocytotic partial release. Correlative imaging with transmission electron microscopy and NanoSIMS imaging and a dual stable isotope labeling approach was used to study the cargo status of vesicles before and after exocytosis; demonstrating a measurable loss of transmitter in individual vesicles following stimulation due to partial release. Model secretory cells were incubated with 13C-labeled l-3,4-dihydroxyphenylalanine, resulting in the loading of 13C-labeled dopamine into their vesicles. A second label, di-N-desethylamiodarone, having the stable isotope 127I, was introduced during stimulation. A significant drop in the level of 13C-labeled dopamine and a reduction in vesicle size, with an increasing level of 127I-, was observed in vesicles of stimulated cells. Colocalization of 13C and 127I- in several vesicles was observed after stimulation. Thus, chemical visualization shows transient opening of vesicles to the exterior of the cell without full release the dopamine cargo. We present a direct calculation for the fraction of neurotransmitter release from combined imaging data. The average vesicular release is 60% of the total catecholamine. An important observation is that extracellular molecules can be introduced to cells during the partial exocytotic release process. This nonendocytic transport process appears to be a general route of entry that might be exploited pharmacologically. © 2022 The Authors. Published by American Chemical Society.
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| 62. |
- Nilsson, Bengt-Olof, et al.
(författare)
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Effects of polyamine synthesis inhibition on polyamines, growth and mechanical properties in hypertrophic rat urinary bladder
- 1998
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Ingår i: Pharmacology and Toxicology. - 1600-0773. ; 82:6, s. 287-294
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Tidskriftsartikel (refereegranskat)abstract
- The polyamines putrescine, spermidine and spermine, are ubiquitous intracellular metabolites associated with growth and protein synthesis. In this study effects of polyamine synthesis inhibition on bladder growth, polyamine levels and mechanical properties were investigated in rat urinary bladder subjected to partial outflow obstruction that causes bladder hypertrophy. The S-adenosyl methionine decarboxylase inhibitor CGP-48664 (5 and 20 mg kg-1) was administered alone or in combination with the ornithine decarboxylase inhibitor DFMO (500 mg kg-1), starting one day before creation of partial outflow obstruction and then daily for 7 days. The bladder muscle level of putrescine was increased 38 times and that of spermine reduced by 4 times while spermidine was unchanged after treatment with CGP-48664 (20 mg kg-1). The increase in putrescine was abolished in animals receiving CGP-48664 in combination with DFMO. Treatment with polyamine synthesis inhibitors could not prevent or reduce the hypertrophy of the bladder as judged by bladder wet weight and protein contents. The effects on polyamine quantities were not associated with changes in Ca(2+)-force relationship or in agonist and electrically stimulated force. In summary, treatment of rats with polyamine synthesis inhibitors resulted in changes in polyamine levels in the growing urinary bladder but did not affect growth or mechanical properties.
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| 63. |
- Rodriguez, Juan, 1983
(författare)
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Targeting apoptosis-inducing factor as a novel therapeutic strategy for preventing perinatal brain injury
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Perinatal complications such as asphyxia can cause brain injuries that are often associated with subsequent neurological deficits. The mechanisms of perinatal brain injury are not fully understood, but mitochondria play a prominent role, not only due to their central function in metabolism, but also because many proteins with apoptosisrelated functions are located in the mitochondrion. Among these proteins, CHCHD4 and apoptosis-inducing factor (AIF) have already been shown to make important contributions to neuronal cell death upon hypoxia-ischemia (HI), but a better understanding of the mechanisms behind these processes is required for the development of improved treatments. By inducing HI in 9-day-old mice, leading to moderate brain injury, we studied these mechanisms from multiple perspectives. First, we determined the effect of chchd4 haploinsufficiency, and we showed that neonatal mice with this genotype experienced less brain damage due to reduced translocation of AIF and Cytochrome c from the mitochondrion. Second, we characterized the role of a newly discovered AIF isoform (AIF2), which is only expressed in the brain and the functions of which are unknown. By using Aif2 knockout mice, we showed that under physiological conditions there is an increase in Aif1 expression (the ubiquitously expressed isoform) due to a compensatory effect of loss of Aif2 expression. As a result, these mice showed a higher degree of brain damage after HI and were more vulnerable to oxidative stress. Third, we used another transgenic mouse in which Aif was overexpressed by knocking in a proviral insertion of Aif, leading to an increased expression of Aif1 without affecting the expression of Aif2. This mouse also showed a higher degree of brain damage and higher levels of oxidative stress. Finally, we used a peptide designed to block the apoptotic function of AIF. The results in young mice showed that the neuroprotective effect of the peptide was greater in male mice than in female mice. In summary, this PhD project has opened new perspectives in the comprehension of the mechanisms by which CHCHD4 and AIF are crucial proteins for brain damage after HI, and it has showed that AIF is a promising therapeutic target for improving outcome after perinatal brain injury.
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| 64. |
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| 65. |
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| 66. |
- Skovgård, Katrine
(författare)
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Models and biomarkers of motor and neuropsychiatric complications in Parkinson’s disease
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Parkinson's disease (PD) is a neurodegenerative disorder characterised by typicalmotor symptoms that are caused by severe dopamine depletion in the cortico-basalganglia network. Parkinsonian motor symptoms are improved by dopaminergicmedications, the most effective being the dopamine precursor L-DOPA. Thiscompound exerts its motor effects by stimulating dopamine D1 and D2 receptors,whose expression are segregated between the movement-promoting and movement-suppressing pathways of the basal ganglia circuitry. As the disease progresses,treatment with L-DOPA give rise to involuntary movements (dyskinesia), whichlimits its utility. Drugs that directly stimulate dopamine receptors, referred to asdopamine agonists, are commonly used to delay the use of L-DOPA or reduce itsdosage. Although less prone to induce dyskinesia, dopamine agonists have a highliability to induce neuropsychiatric side effects, in particular, impulsive-compulsivebehaviours. However, it remains to be established whether pharmacotherapiescombining L-DOPA and dopamine agonists give rise to specific profiles of motorand non-motor complications.The overarching aim of this thesis is to develop improved experimental modelsto advance translational research on the motor and neuropsychiatric complicationsof PD therapy. Both well-established and new experimental models are used todefine correlations and causal links between regimens of dopaminergic treatment,behavioural changes, and biomarkers of network and cellular dysfunction in thecortico-basal ganglia system.Using in vivo local field potential recordings to study biomarkers of networkdysfunctions, we show that changes in broad-band oscillatory activities of cortico-striatal circuits are correlated to ongoing motions and do not reflect parkinsonian-specific states. Moreover, we demonstrate that dyskinesias induced by D1 receptorstimulation are associated with prominent narrowband cortico-striatal oscillationsin the high gamma range (70-110 Hz). Following treatment with a D2 agonist, thesenarrowband gamma oscillations are less pronounced, whereas this treatment inducesprominent theta oscillations (5-10 Hz) in the deep basal ganglia nuclei. Thus, thecomposition of the dopaminergic therapies might affect these neurophysiologicalbiomarkers and should be considered in future investigations.Next, using a set of pharmacological tools and markers of cellular dysfunctions,we show that adjuvant treatment with D2/3 agonists alters the pattern of dopamine-related neuroplasticity in the basal ganglia compared to L-DOPA monotherapy,despite similar dyskinetic behaviours. The antidyskinetic effects of compounds modulating D1 receptor signalling were stronger in L-DOPA-treated animals, whileNMDA receptor antagonists produced markedly larger effects in the combinedtreatment group. Thus, adjuvant dopamine agonist treatment has a significantimpact on the neuroplasticity and pharmacological response profiles of L-DOPA-induced dyskinesia. In a last study, we show that treatment with a D2/3 agonistinduces compulsive behaviours and impulsive decision-making in both intact andpartially dopamine-depleted rats regardless of L-DOPA coadministration.Taken together, the findings of this thesis shed new light on the maladaptivecellular changes and network dynamics through which dopaminergic pharmacotherapies for PD affects motor behaviours. Moreover, this thesis work reveals the importance of including realistic models of combined therapies in future translational research on L-DOPA-induced dyskinesia.
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| 67. |
- Vieira, João
(författare)
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Profiling Plasma Metabolite Alterations in Diet-Induced Obesity and Diabetes Using NMR Metabolomics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diets rich in saturated fat and sedentary lifestyles markedly contribute to obesity and metabolic syndrome-related diseases, including type 2 diabetes mellitus (T2D). Metabolite profiling plays a pivotal role in understanding these metabolic diseases. This thesis comprises insights from four distinct studies to illuminate metabolic imbalances induced by diet-induced obesity (DIO), covering topics related to the duration of dietary regimens, potential benefits of dietary interventions on the brain and metabolism, and the impact of underlying T2D on post-stroke recovery. Using a combination of proton nuclear magnetic resonance (1H-NMR) spectroscopy and mass spectrometry (MS), study I initially demonstrated the superiority of the combined approach in characterizing the effects of DIO on plasma metabolites. The robustness of this method was further validated in a human cohort, underscoring its translational potential in unravelling metabolic imbalances. In study II, female mice exposed to high-fat diet (HFD) exhibited brain metabolism alterations and memory deficits, which were mitigated by taurine and N-acetylcysteine (NAC) supplementation. These supplements not only ameliorated HFD-induced memory impairment but also elicited distinct effects on metabolic alterations within the hippocampus. Systemically, 1H-NMR metabolomics data in study III revealed that NAC and taurine treatments impacted plasma metabolites. Ultimately, as explored in study IV using 1H-NMR metabolomics, unique metabolite changes in male mice with T2D following transient middle cerebral artery occlusion were reported. Specifically, metabolite changes that link T2D to poor neurological outcomes after stroke were observed. In summary, this thesis underscores the significance of metabolite profiling in elucidating the complexities of metabolic diseases, memory impairment, and post-stroke recovery in DIO mouse models. It also emphasizes the translational character of such findings to human pathophysiology.
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| 68. |
- Zhu, Changlian, 1964, et al.
(författare)
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X chromosome-linked inhibitor of apoptosis protein reduces oxidative stress after cerebral irradiation or hypoxia-ischemia through up-regulation of mitochondrial antioxidants.
- 2007
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Ingår i: The European journal of neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 26:12, s. 3402-10
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that X chromosome-linked inhibitor of apoptosis protein (XIAP) counteracts oxidative stress in two essentially different disease-related models of brain injury, hypoxia-ischemia and irradiation, as judged by lower expression of nitrotyrosine (5-fold) and 4-hydroxy-2-nonenal (10-fold) in XIAP-overexpressing compared with wild-type mice. XIAP overexpression induced up-regulation of at least three antioxidants residing in mitochondria, superoxide dismutase 2, thioredoxin 2 and lysine oxoglutarate reductase. Cytochrome c release from mitochondria was reduced in XIAP-overexpressing mice. Hence, in addition to blocking caspases, XIAP can regulate reactive oxygen species in the brain, at least partly through up-regulation of mitochondrial antioxidants. XIAP-induced prevention of oxidative stress was not secondary to tissue protection because although XIAP overexpression provides tissue protection after hypoxia-ischemia, it does not prevent tissue loss after irradiation. This is a previously unknown role of XIAP and may provide the basis for development of novel protective strategies for both acute and chronic neurodegenerative diseases, where oxidative stress is an integral component of the injury mechanisms involved.
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| 69. |
- Österman, Å, et al.
(författare)
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Effects of 2,3-butanedione monoxime on activation of contraction and crossbridge kinetics in intact and chemically skinned smooth muscle fibres from guinea pig taenia coli
- 1993
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Ingår i: Journal of Muscle Research and Cell Motility. - 0142-4319. ; 14:2, s. 186-194
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Tidskriftsartikel (refereegranskat)abstract
- The effects of 2,3-butanedione monoxime (BDM) were studied in smooth muscle fibres from guinea pig taenia coli. In intact muscle, active force during contractions induced by high-K+ was inhibited by about 10% in 1 mM BDM and by approximately 70% in 10 mM BDM. Intracellular [Ca2+] during contraction, measured with the fura-2 technique, was reduced in the presence of BDM. The reduction in force and [Ca2+] in the presence of 1 and 10 mM BDM could be reproduced by reduction in extracellular Ca2+, suggesting that BDM influences the Ca2+ entry or release. In skinned muscle preparations, BDM decreased the Ca2+ sensitivity of active force. This change could be explained by a decreased level of myosin light chain phosphorylation. In fibres maximally activated by thiophosphorylation, the effect of BDM on force occurred at higher concentrations; 10 mM gave no reduction of force and 60 mM 15% reduction. The maximal shortening velocity (Vmax) and force were unaffected by 30 mM BDM in thiophosphorylated muscle and decreased almost in parallel in Ca(2+)-activated contractions. The present results suggest that BDM inhibits myosin light chain phosphorylation, directly decreases force generation at the crossbridge level and inhibits the Ca2+ translocation in smooth muscle. The effect on force in skinned fibres is observed at higher BDM concentrations than those reported to be required for inhibition of force in striated muscle. The inhibition of force in intact smooth muscle could be explained by an influence on Ca2+ translocation.
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| 70. |
- Asghar, Afshan, et al.
(författare)
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"Ficus johannis Boiss. leaves ethanolic extract ameliorate streptozotocin-induced diabetes in rats by upregulating the expressions of GCK, GLUT4, and IGF and downregulating G6P"
- 2023
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Ingår i: Environmental Science and Pollution Research. - : Springer Nature. - 0944-1344 .- 1614-7499. ; 30:17, s. 49108-49124
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Tidskriftsartikel (refereegranskat)abstract
- The leaves of Ficus johannis Boiss (F. johannis), commonly known as Fig tree, Anjir, and Teen, are used by the folk medicinal practitioners in Iran for controlling hyperglycemia in diabetic patients. This study investigated the pharmacological basis for antidiabetic effect of the ethanolic extract of F. johannis leaves using in vitro and in vivo experimental models. Qualitative screening of phytochemicals, estimation of total phenolic and flavonoid contents, and in vitro antioxidant and α-amylase inhibition assays were performed. Moreover, the High-performance liquid chromatography (HPLC) quantification, acute toxicity, glucose tolerance, and in vivo antidiabetic effect along with the evaluation of gene expressions involved in diabetes mellitus were carried out. Significant quantities of phenolic (71.208 ± 2.89 mgg−1 GAE) and flavonoid (26.38 ± 3.53 mgg−1 QE) were present. Inhibitory concentration (IC50) of the plant extract exhibited an excellent in vitro antioxidant (IC50 = 33.81 µg/mL) and α-amylase (IC50 = 12.18 µg/mL) inhibitory potential. The HPLC analysis confirmed the gallic acid (257.79 mgg−1) as main constituent of the extract followed by kaempferol (22.86 mgg−1), myricetin (0.16 mgg−1), and quercetin (3.22 mgg−1). Ethanolic extract displayed glucose tolerance in normo-glycemic rats. Streptozotocin-induced hyperglycemia declined dose dependently in the extract treated rats with improvement in lipid profile and liver and renal function biomarkers. The F. johannis-treated groups showed an increase in mRNA expressions of glucose transporter 4 (GLUT-4), glucokinase, insulin growth like factor 1 and peroxisomal proliferator activating receptor gamma in pancreas. However, the Glucose-6-phosphatase was downregulated. Present study suggests that the ethanolic extract of F. johannis leaves demonstrates a good anti-diabetic profile by improving insulin sensitivity, GLUT-4 translocation, and carbohydrate metabolism while inhibiting lipogenesis.
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