| 1. |
- Belfrage, Per, et al.
(författare)
-
Dispersion of viable pig liver cells with collagenase
- 1975
-
Ingår i: Life Sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 17:8, s. 1219-1225
-
Tidskriftsartikel (refereegranskat)abstract
- Viable suspended hepatocytes were prepared from surgical biopsy specimens of pig and human liver by digestion with collagenase. Initial perfusion of the tissue through cannulated blood vessels with 0.5 mM EGTA followed by 0.2% collagenase gave the best results. 20−870 × 106 cells of which 60–95 % excluded trypan blue were obtained from 5–30 g pig liver pieces, while results with human liver specimens were usually less satisfactory. In some experiments, however, viable cells, as judged by vital stain exclusion and ability to synthesize lipids were obtained in sufficient yield. In the pig hepatocytes glycerolipid synthesis from [3H] glycerol and oxidation and esterification of [14C] oleic acid had the same characteristics as those observed earlier in rat hepatocytes.
|
|
| 2. |
- Björkman, Sven, et al.
(författare)
-
Cerebral uptake of morphine in the pig calculated from arterio-venous plasma concentration gradients: an alternative to tissue microdialysis
- 1995
-
Ingår i: Life Sciences. - 1879-0631 .- 0024-3205. ; 57:25, s. 2335-2345
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to characterize the reversible cerebral uptake of morphine in the pig by measuring the changing arterio-venous plasma concentration gradient over the brain. Seven pigs were anaesthetized by continuous infusions of ketamine and pancuronium and ventilated with oxygen in nitrous oxide. During and after 5-min intravenous infusions of morphine hydrochloride, blood samples were drawn from a central artery and from the internal jugular vein. Concomitantly, cerebral blood flow (CBF) was repeatedly measured as clearance of 133Xe from the brain after intracarotid injection. Plasma concentrations of morphine and, in samples from two animals, morphine glucuronides were assayed by high-performance liquid chromatography. Drug flux (Jnet) from arterial blood to brain was calculated from the arterio-venous plasma concentration gradients, the blood:plasma concentration ratio and CBF. Uptake of morphine from arterial blood to brain was very rapid, with a maximal Jnet typically at 3 min after the beginning of the infusion. The initial cerebral extraction of morphine was close to 50%. When the arterial and jugular venous concentration curves crossed, 1-5 min after the end of the infusion, the initially rapid uptake of morphine changed into a slow and steady release. The cerebral extraction of morphine glucuronides was comparable to that of morphine, however, Jnet was lower due to lower plasma concentrations at time of maximal extraction. The findings demonstrate how the cerebral uptake and release of morphine and its metabolites can be studied with a method that is entirely non-invasive to the brain and permits very flexible sampling. Uptake and release of drug is observed directly and need not be inferred from cerebral concentration curves.
|
|
| 3. |
- Nilsson-Ehle, Peter, et al.
(författare)
-
Specific conditions for enhancement of lipoprotein lipase activity by platelets
- 1975
-
Ingår i: Life Sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 16:11, s. 1703-1709
-
Tidskriftsartikel (refereegranskat)abstract
- Homogenates of human blood platelets, but not of red blood cells, have been found to stimulate lipoprotein lipase activity only when assayed against an emulsified triglyceride substrate sonicated for a short period of time. The degree of stimulation was inversely related to the time of sonication of the substrate. Using chylomicrons as substrate no stimulation of lipoprotein lipase activity by platelet homogenate was seen.
|
|
| 4. |
- Simonsson, Per, et al.
(författare)
-
The 5-hydroxytryptamine stimulated formation of inositol phosphate is inhibited in platelets from alcoholics
- 1988
-
Ingår i: Life Sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 42:4, s. 385-391
-
Tidskriftsartikel (refereegranskat)abstract
- The accumulation of inositol monophosphate (IP1) was measured after stimulation of 5-hydroxytryptamine2 (5-HT2) receptors on platelets from alcoholics and healthy controls. In controls, 5-HT induced a dose-dependent response with an EC50 = 2 x 10(-6) M and a maximal response at 10(-5) M. Ritanserin, a selective 5-HT2 antagonist, markedly reduced the accumulation. The IP1 formation after stimulation by 10(-5) M 5-HT was significantly impaired in platelets from alcoholics as compared to controls. This study indicates that the 5-HT2 receptor function is inhibited in alcoholics. It also illustrates the possibility of using IP1 formation in peripheral cells as a mean of studying receptor function in disease.
|
|
| 5. |
- Calles-Escandon, Jorge, et al.
(författare)
-
The membrane-associated 40 KD fatty acid binding protein(Berk's protein), a putative fatty acid transporter is present in human skeletal muscle
- 1995
-
Ingår i: Life Sciences. - : Elsevier. - 0024-3205 .- 1879-0631. ; 58:1, s. 19-28
-
Tidskriftsartikel (refereegranskat)abstract
- Muscle tissue (1.1 +/- 0.1 grams) was obtained from seven healthy individuals (3 males, 4 females) using an open incision approach before and after ingestion of either 75 grams of dextrose (N=5) or water (N=2). Purified sarcolemmal membranes from the muscle were prepared using a sucrose step gradient. A polyclonal antibody raised against the purified (99%) rat hepatocyte 40 KD membrane fatty acid binding protein (mFABP-L) was used to probe for this putative transporter in the muscle membranes using Western blot. A single band at the 40 KD MW band was identified which reacted antigenically with the proteinpurified from rat livers. These response of Berk's protein 60-75 minutes after dextrose ingestion (or water) was erratic and no specific trend could be identified. Our data demonstrate that the 40 KD mFABP-L originally isolated from rat liver is also present in human skeletal muscle membrane. This protein may be involved in transport of fatty acids across the membrane of skeletal muscle, however its physiological role in human fatty acidmetabolism remains to be established.
|
|
| 6. |
- Martensson, L.G.E., et al.
(författare)
-
Is Ca2+ the second messenger in the response to melatonin in cuckoo wrasse melanophores?
- 2000
-
Ingår i: Life Sciences. - 0024-3205 .- 1879-0631. ; 66:11, s. 1003-1010
-
Tidskriftsartikel (refereegranskat)abstract
- Pigment aggregation in melanophores of Labrus ossifagus is controlled by an a2-adrenoceptor and is somehow modulated by melatonin. The signal transduction mechanisms seem to involve both an attenuation of cAMP and an increase in intracellular Ca2+, inhibiting protein kinase A or activating a phosphatase, respectively. These effects result in dephosphorylation, which in turn induces aggregation. Various a2-adrenoceptor agonists attenuate cAMP levels or increase the concentration of intracellular Ca2+. Noradrenaline, for example, lowers cAMP but does not affect the calcium signal whereas B-HT 920, an a2-adrenoceptor specific agonist, does not induce a cAMP decrease but does appear to induce an increase in intracellular Ca2+. This later inference is drawn from experiments with BAPTA/AM, an intracellular calcium chelator, which counteracts the aggregation induced by B-HT 920. Interestingly, the very potent a2-adrenoceptor agonist medetomidine apparently activates both signal transduction pathways, which could explain its high efficacy in producing aggregation. Melatonin itself does not cause pigment aggregation, but it potentiates noradrenaline-induced aggregation. It has been suggested that melatonin receptors and a2- adrenoceptors follow the same signal transduction pathway, i.e. an attenuation of cAMP. In our experiments, melatonin did not reduce cAMP levels, instead it appears to increase Ca2+ concentration, since melatonin- potentiated aggregation was inhibited by BAPTA/AM. Thus, aggregation amplified by melatonin is probably not mediated by a further decrease in cAMP, but by the same signal transduction mechanism as B-HT 920, i.e. an increase in Ca2+. This further strengthens the suggestion that melatonin and B-HT 920 bind to the same site, but it is unclear if that particular site is on the melatonin receptor or the a2-adrenoceptor.
|
|
| 7. |
- Åkerman, Karl E. O., et al.
(författare)
-
Voltage gated calcium channels potentiate muscarinic receptor-mediated calcium responses in SH-SY5Y human neuroblastoma cells
- 1997
-
Ingår i: Life Sciences. - 0024-3205 .- 1879-0631. ; 60:13-14, s. 1189-
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Muscarinic receptor-mediated Ca2+ elevations were investigated using the fura-2 method and image analysis. Typical responses consisted of an initial fast and transient phase followed by a sustained phase. Removal of external Ca2+ did not affect the magnitude of the initial phase of the signal whereas the sustained phase was abolished. Hence they may mainly consist of a release from intracellular stores and an influx, respectively. Depolarization of the cells with 30 mM KCl in the presence of external Ca2+ caused a small elevation of [Ca2+]i. In these conditions a considerable potentiation of the fast phase of muscarinic Ca2+ response was seen. The potentiation was dependent on the extracellular Ca2+ as it was abolished in the presence of antagonists of voltage-gated Ca2+ channels or by removal of external Ca2+ prior to KCl. Removal of external Ca2+ after the KCl-induced increase in [Ca2+]i partially inhibited the potentiation. If Ca2+ was readded together with the muscarinic stimulation a maximum potentiation was seen. The results suggest that the muscarinic response is potentiated by a Ca2+-mediated priming of both a fast and transient receptor associated Ca2+ influx pathway and release from the intracellular stores.
|
|
| 8. |
- Abohalaka, Reshed, et al.
(författare)
-
Endocannabinoid metabolism inhibition ameliorates ovalbumin-induced allergic airway inflammation and hyperreactivity in Guinea pigs.
- 2022
-
Ingår i: Life sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 306
-
Tidskriftsartikel (refereegranskat)abstract
- Endocannabinoids are biologically active cannabinoid-related substances endogenously synthesized in many mammalian tissues. Mainly two enzymes carry out their degradation; Fatty Acid Amide Hydrolase (FAAH) and Monoacylglycerol Lipase (MAGL). Endocannabinoids are shown to affect the modulation of inflammatory processes and airway responsiveness. In the present study, we investigated the effects of FAAH and MAGL inhibitor treatments in experimental allergic airway inflammation in guinea pigs.Guinea pigs were sensitized and challenged by ovalbumin to induce an allergic asthma model. Then, the effects of FAAH inhibitor URB597, MAGL inhibitor JZL184, and dual (FAAH/MAGL) inhibitor JZL195 on airway inflammation and hyperreactivity were evaluated.Ovalbumin challenge increased airway reactivity, IgE in serum, IL-4, and IL-13, and the percentage of eosinophils in bronchoalveolar lavage (BAL). In addition, inhibition of FAAH or MAGL enzymes leads to an increase in endocannabinoid levels. The selective inhibition of the FAAH enzyme prevented inflammation indicators such as cytokine production and inflammatory cell infiltration but had a negligible effect on airway hyperreactivity. However, the inhibition of the MAGL enzyme or dual inhibition of both FAAH and MAGL enzymes tent to moderate both pulmonary inflammation and airway hyperreactivity.We have previously demonstrated that modulation of endocannabinoid levels in the airways by FAAH or MAGL inhibition can be useful in preventing acute lung inflammation. The results of the present study further suggest that FAAH and MAGL inhibitor treatment can also be a promising strategy for bronchial hyperreactivity and airway inflammation in allergic asthma.
|
|
| 9. |
|
|
| 10. |
- Akbari, Ali, et al.
(författare)
-
Free and hydrogel encapsulated exosome-based therapies in regenerative medicine.
- 2020
-
Ingår i: Life sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 249
-
Tidskriftsartikel (refereegranskat)abstract
- Over the last few decades, mesenchymal stem cells-derived exosomes (MSCs-Ex) have attracted a lot of attention as a therapeutic tool in regenerative medicine. Exosomes are extracellular vehicles (EVs) that play important roles in cell-cell communication through various processes such as stress response, senescence, angiogenesis, and cell differentiation. Success in the field of regenerative medicine sparked exploration of the potential use of exosomes as key therapeutic effectors of MSCs to promote tissue regeneration. Various approaches including direct injection, intravenous injection, intraperitoneal injection, oral administration, and hydrogel-based encapsulation have been exploited to deliver exosomes to target tissues in different disease models. Despite significant advances in exosome therapy, it is unclear which approach is more effective for administering exosomes. Herein, we critically review the emerging progress in the applications of exosomes in the form of free or association with hydrogels as therapeutic agents for applications in regenerative medicine.
|
|
