scholarly journals LECITHIN SYNTHESIS, INTRACELLULAR TRANSPORT, AND SECRETION IN RAT LIVER

1969 ◽  
Vol 40 (2) ◽  
pp. 461-483 ◽  
Author(s):  
Olga Stein ◽  
Yechezkiel Stein
Keyword(s):  
Endoplasmic Reticulum ◽  
Liver Cell ◽  
Phosphatidyl Choline ◽  
Intracellular Transport ◽  
Phosphatidyl Ethanolamine ◽  
Specific Activity ◽  
Perfused Liver ◽  
Precursor Pool

Injection of choline-3H into choline-deficient rats resulted in an enhanced incorporation of the label into liver lecithin, as compared to the incorporation of label into liver lecithin of normal rats. The results obtained with the use of different lecithin precursors indicate that in the intact liver cell, both in vivo and in vitro, exchange of choline with phosphatidyl-choline is not significant. The synthesis and secretion of lecithins by the choline-deficient liver compare favorably with the liver of choline-supplemented rats, when both are presented with labeled choline or lysolecithin as lecithin precursors. Radioautography of the choline-deficient liver shows that 5 min after injection of choline-3H the newly synthesized lecithin is found in the endoplasmic reticulum (62%), mitochondria (13%), and at the "cell boundary" (20%). The ratio of the specific activity of microsomal and mitochondrial lecithin, labeled with choline, glycerol, or linoleate, was 1.53 at 5 min after injection, but the ratio of the specific activity of phosphatidyl ethanolamine (PE), labeled with ethanolamine, was 5.3. These results indicate that lecithin and PE are synthesized mainly in the endoplasmic reticulum, and are transferred into mitochondria at different rates. The site of a precursor pool of bile lecithin was studied in the intact rat and in the perfused liver. Following labeling with choline-3H, microsomal lecithin isolated from perfused liver had a specific activity lower than that of bile lecithin, but the specific activity of microsomal linoleyl lecithin was comparable to that of bile lecithin between 30 and 90 min of perfusion. It is proposed that the site of the bile lecithin pool is located in the endoplasmic reticulum and that the pool consists mostly of linoleyl lecithin.

Phosphatidylethanolamine in Liver Mitochondria and Endoplasmic Reticulum; Molecular Species Distribution and Turnover

1975 ◽  
Vol 53 (6) ◽  
pp. 698-705 ◽  
Author(s):  
J. G. Parkes ◽  
W. Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Fatty Acid ◽  
Specific Activity ◽  
Liver Mitochondria ◽  
Relative Activity ◽  
Layer Chromatography ◽  
Kinetics Of ◽  
Fatty Acid Compositions

Phosphatidylethanolamine from mitochondria and microsomes of guinea pig liver was separated by thin-layer chromatography into eight different classes differing in degree of unsaturation. The fatty acid compositions and molar proportions of each class isolated from microsomes were very similar to the corresponding class in mitochondria. In both organelles about half of the total was dienoic species while tetraenes comprised approximately 20%. Stearic acid was the major saturated fatty acid and in each membrane a greater selectivity for stearate over palmitate was found in each sub-class of phosphatidylethanolamine, when compared with the corresponding class of phosphatidylcholine.Following the intraperitoneal injection of [2-3H]glycerol, the labelling of each molecular class of phosphatidylethanolamine showed very similar progressions in microsomes and mitochondria over a 3 h interval. In both organelles the highest relative specific activity was attained by penta-plus hexaenoic classes, while the large dienoic class had the lowest relative activity, which, however, increased with time. Analysis of the dienoic class of phosphatidylethanolamine from whole liver showed it to be constituted by a rapidly turning over palmitoyl–linoleoyl fraction and a slowly labelled stearoyl–linoleoyl fraction, a pattern also exhibited by dienoic phosphatidylcholines.The similarities in profile of molecular classes of phosphatidylethanolamine and in the kinetics of labelling in vivo point to a close metabolic relation between the lipids of both organelles, suggestive of a transfer of different molecular classes at comparable rates from the endoplasmic reticulum, the site of synthesis, to the mitochondria. This is consistent with numerous other studies in vitro that have demonstrated inter-organelle exchange of lipids.

scholarly journals EVIDENCE FOR THE PARTICIPATION OF THE GOLGI APPARATUS IN THE INTRACELLULAR TRANSPORT OF NASCENT ALBUMIN IN THE LIVER CELL

1970 ◽  
Vol 47 (3) ◽  
pp. 555-567 ◽  
Author(s):  
Hans Glaumann ◽  
Jan L. E. Ericsson
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Liver Cell ◽  
Intracellular Transport ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Parenchymal Liver Cell ◽  
Parenchymal Liver ◽  
Membrane Bound

A comparative biochemical and radioautographic in vivo study was performed to identify the site of synthesis and route of migration of albumin in the parenchymal liver cell after labeling with leucine-14C or leucine-3H via the portal vein. Free cytoplasmic ribosomes, membrane-bound ribosomes, rough- and smooth-surfaced microsomes, and Golgi membranes were isolated. The purity of the Golgi fraction was examined morphologically and biochemically. After administration of leucine-14C, labeled albumin was extracted, and the sequence of transport was followed from one fraction to the other. Approximately 2 min after the intravenous injection, bound ribosomes displayed a maximal rate of leucine-14C incorporation into albumin. 4 min later, a peak was reached for rough microsomes. Corresponding maximal activities for smooth microsomes were recorded at 15 min, and for the Golgi apparatus at ∼20 min. The relative amount of albumin, calculated on a membrane protein basis, was higher in the Golgi fraction than in the microsomes. By radioautography the silver grains were preferentially localized over the rough-surfaced endoplasmic reticulum at the 5 min interval. Apparent activity in the Golgi zone was noted 9 min after the injection; at 15 and 20 min, the majority of the grains were found in this location. Many of the grains associated with the Golgi apparatus were located over Golgi vacuoles containing 300–800 A electron-opaque bodies. It is concluded that albumin is synthesized on bound ribosomes, subsequently is transferred to the cavities of rough-surfaced endoplasmic reticulum, and then undergoes migration to the smooth-surfaced endoplasmic reticulum and the Golgi apparatus. In the latter organelle, albumin can be expected to be segregated together with very low density lipoprotein in vacuoles known to move toward the sinusoidal portion of the cell and release their content to the blood.

scholarly journals THE ABSORPTION OF FAT BY INTESTINE OF GOLDEN HAMSTER IN VITRO

1963 ◽  
Vol 17 (3) ◽  
pp. 597-607 ◽  
Author(s):  
Elliott W. Strauss
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Bile Salts ◽  
Intracellular Transport ◽  
Light And Electron Microscopy ◽  
Lipid Absorption ◽  
Apical Cytoplasm ◽  
Everted Sacs

Everted sacs of intestine from golden hamsters were incubated at 37°C for at least 1 hour in vitro with emulsified lipid after removal of both pancreatic lipase and bile salts. The fine structure of intestinal epithelium is well preserved under these conditions. Absorption of fat by the intestinal mucosa in vitro closely resembles lipid absorption in vivo, as observed by both light and electron microscopy. The physiological significance of these observations is discussed. Tubular elements of the agranular endoplasmic reticulum are often strikingly abundant in the apical cytoplasm of intestinal absorptive cells. These have a role in the intracellular transport of fat since they frequently contain droplets of lipid derived from the incubation medium. The rate of fat accumulation in the epithelium appears to be proportional to the concentration in the medium.

scholarly journals An Endoplasmic Reticulum Protein, p180, Is Highly Expressed in Human Cytomegalovirus-Permissive Cells and Interacts with the Tegument Protein Encoded by UL48

2002 ◽  
Vol 76 (5) ◽  
pp. 2350-2362 ◽  
Author(s):  
K. Ogawa-Goto ◽  
S. Irie ◽  
A. Omori ◽  
Y. Miura ◽  
H. Katano ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Human Cytomegalovirus ◽  
Intracellular Transport ◽  
Late Phase ◽  
Terminal Region ◽  
Electron Microscopic ◽  
Replication Process ◽  
Overlay Assay

ABSTRACT We have used a virus overlay assay to detect cellular proteins associated with human cytomegalovirus (HCMV) particles. The radiolabeled HCMV particles specifically bound to two host proteins with molecular sizes of 150 and 180 kDa. By a micro-amino-acid sequencing technique, the 180-kDa protein was identified as a human homologue of the ES130/p180 ribosome receptor (p180), which is an integral endoplasmic reticulum (ER) membrane protein possessing a very unique tandem repeat domain at its N-terminal region. The virus overlay assay using truncated p180 polypeptides revealed that HCMV binding to human p180 occurred through the N-terminal region. In HCMV-permissive cells the high level of expression of the human p180 protein was clearly observed regardless of cell type. Furthermore, we showed that p180 binds to the UL48 gene product, which is one of the predominant tegument proteins of HCMV and which is considered to be tightly associated with the capsid. The interaction between the two proteins was assumed to be specific and was observed both in vitro and in vivo. During the late phase of infection, the unique relocation of human p180 was observed, that is, to the juxtanuclear region, which appeared to be in the vicinity of the area where naked virions were frequently observed in an electron-microscopic study. Thus our data suggest that p180 interacts with the HCMV tegument, at least through pUL48, during the HCMV replication process. We discuss the possible role of the interaction between p180 and pUL48 in the intracellular transport of HCMV virions.

Soluble Thrombomodulin Purified from Human Urine Exhibits a Potent Anticoagulant Effect In Vitro and In Vivo

1995 ◽  
Vol 73 (05) ◽  
pp. 805-811 ◽  
Author(s):  
Yasuo Takahashi ◽  
Yoshitaka Hosaka ◽  
Hiromi Niina ◽  
Katsuaki Nagasawa ◽  
Masaaki Naotsuka ◽  
...  
Keyword(s):  
Human Urine ◽  
Specific Activity ◽  
Anticoagulant Activity ◽  
Rabbit Lung ◽  
Soluble Thrombomodulin ◽  
Molecular Weights ◽  
Dose Dependent Fashion ◽  
Dose Dependent

SummaryWe examined the anticoagulant activity of two major molecules of soluble thrombomodulin purified from human urine. The apparent molecular weights of these urinary thrombomodulins (UTMs) were 72,000 and 79,000, respectively. Both UTMs showed more potent cofactor activity for protein C activation [specific activity >5,000 thrombomodulin units (TMU)/mg] than human placental thrombomodulin (2,180 TMU/mg) and rabbit lung thrombomodulin (1,980 TMU/mg). The UTMs prolonged thrombin-induced fibrinogen clotting time (>1 TMU/ml), APTT (>5 TMU/ml), TT (>5 TMU/ml) and PT (>40 TMU/ml) in a dose-dependent fashion. These effects appeared in the concentration range of soluble thrombomodulins present in human plasma and urine. In the rat DIC model induced by thromboplastin, administration of UTMs by infusion (300-3,000 TMU/kg) restored the hematological abnormalities derived from DIC in a dose-dependent fashion. These results demonstrate that UTMs exhibit potent anticoagulant and antithrombotic activities, and could play a physiologically important role in microcirculation.

Effects of Heparin Oligosaccharides with High Affinity for Antithrombin III in Experimental Venous Thrombosis

1982 ◽  
Vol 47 (03) ◽  
pp. 244-248 ◽  
Author(s):  
D P Thomas ◽  
Rosemary E Merton ◽  
T W Barrowcliffe ◽  
L Thunberg ◽  
U Lindahl
Keyword(s):  
Antithrombin Iii ◽  
Specific Activity ◽  
High Specific Activity ◽  
Factor Xa ◽  
Blood Levels ◽  
Thrombin Time ◽  
High Affinity ◽  
Very High

SummaryThe in vitro and in vivo characteristics of two oligosaccharide heparin fragments have been compared to those of unfractionated mucosal heparin. A decasaccharide fragment had essentially no activity by APTT or calcium thrombin time assays in vitro, but possessed very high specific activity by anti-Factor Xa assays. When injected into rabbits at doses of up to 80 ¼g/kg, this fragment was relatively ineffective in impairing stasis thrombosis despite producing high blood levels by anti-Xa assays. A 16-18 monosaccharide fragment had even higher specific activity (almost 2000 iu/mg) by chromogenic substrate anti-Xa assay, with minimal activity by APTT. When injected in vivo, this fragment gave low blood levels by APTT, very high anti-Xa levels, and was more effective in preventing thrombosis than the decasaccharide fragment. However, in comparison with unfractionated heparin, the 16-18 monosaccharide fragment was only partially effective in preventing thrombosis, despite producing much higher blood levels by anti-Xa assays.It is concluded that the high-affinity binding of a heparin fragment to antithrombin III does not by itself impair venous thrombogenesis, and that the anti-Factor Xa activity of heparin is only a partial expression of its therapeutic potential.

scholarly journals A novel PET tracer 18F-deoxy-thiamine: synthesis, metabolic kinetics, and evaluation on cerebral thiamine metabolism status

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Changpeng Wang ◽  
Siwei Zhang ◽  
Yuefei Zou ◽  
Hongzhao Ma ◽  
Donglang Jiang ◽  
...  
Keyword(s):  
High Performance ◽  
Specific Activity ◽  
High Accumulation ◽  
Metabolic Kinetics ◽  
Thiamine Metabolism ◽  
Pet Tracer ◽  
The Status ◽  
The Brain

Abstract Background Some neuropsychological diseases are associated with abnormal thiamine metabolism, including Korsakoff–Wernicke syndrome and Alzheimer’s disease. However, in vivo detection of the status of brain thiamine metabolism is still unavailable and needs to be developed. Methods A novel PET tracer of 18F-deoxy-thiamine was synthesized using an automated module via a two-step route. The main quality control parameters, such as specific activity and radiochemical purity, were evaluated by high-performance liquid chromatography (HPLC). Radiochemical concentration was determined by radioactivity calibrator. Metabolic kinetics and the level of 18F-deoxy-thiamine in brains of mice and marmosets were studied by micro-positron emission tomography/computed tomography (PET/CT). In vivo stability, renal excretion rate, and biodistribution of 18F-deoxy-thiamine in the mice were assayed using HPLC and γ-counter, respectively. Also, the correlation between the retention of cerebral 18F-deoxy-thiamine in 60 min after injection as represented by the area under the curve (AUC) and blood thiamine levels was investigated. Results The 18F-deoxy-thiamine was stable both in vitro and in vivo. The uptake and clearance of 18F-deoxy-thiamine were quick in the mice. It reached the max standard uptake value (SUVmax) of 4.61 ± 0.53 in the liver within 1 min, 18.67 ± 7.04 in the kidney within half a minute. The SUV dropped to 0.72 ± 0.05 and 0.77 ± 0.35 after 60 min of injection in the liver and kidney, respectively. After injection, kidney, liver, and pancreas exhibited high accumulation level of 18F-deoxy-thiamine, while brain, muscle, fat, and gonad showed low accumulation concentration, consistent with previous reports on thiamine distribution in mice. Within 90 min after injection, the level of 18F-deoxy-thiamine in the brain of C57BL/6 mice with thiamine deficiency (TD) was 1.9 times higher than that in control mice, and was 3.1 times higher in ICR mice with TD than that in control mice. The AUC of the tracer in the brain of marmosets within 60 min was 29.33 ± 5.15 and negatively correlated with blood thiamine diphosphate levels (r = − 0.985, p = 0.015). Conclusion The 18F-deoxy-thiamine meets the requirements for ideal PET tracer for in vivo detecting the status of cerebral thiamine metabolism.

scholarly journals Dehydrodiisoeugenol inhibits colorectal cancer growth by endoplasmic reticulum stress-induced autophagic pathways

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Changhong Li ◽  
Kui Zhang ◽  
Guangzhao Pan ◽  
Haoyan Ji ◽  
Chongyang Li ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Endoplasmic Reticulum ◽  
Cell Growth ◽  
Er Stress ◽  
Cancer Cells ◽  
Tumor Xenograft ◽  
Anticancer Activities ◽  
Colorectal Cancer Cells

Abstract Background Dehydrodiisoeugenol (DEH), a novel lignan component extracted from nutmeg, which is the seed of Myristica fragrans Houtt, displays noticeable anti-inflammatory and anti-allergic effects in digestive system diseases. However, the mechanism of its anticancer activity in gastrointestinal cancer remains to be investigated. Methods In this study, the anticancer effect of DEH on human colorectal cancer and its underlying mechanism were evaluated. Assays including MTT, EdU, Plate clone formation, Soft agar, Flow cytometry, Electron microscopy, Immunofluorescence and Western blotting were used in vitro. The CDX and PDX tumor xenograft models were used in vivo. Results Our findings indicated that treatment with DEH arrested the cell cycle of colorectal cancer cells at the G1/S phase, leading to significant inhibition in cell growth. Moreover, DEH induced strong cellular autophagy, which could be inhibited through autophagic inhibitors, with a rction in the DEH-induced inhibition of cell growth in colorectal cancer cells. Further analysis indicated that DEH also induced endoplasmic reticulum (ER) stress and subsequently stimulated autophagy through the activation of PERK/eIF2α and IRE1α/XBP-1 s/CHOP pathways. Knockdown of PERK or IRE1α significantly decreased DEH-induced autophagy and retrieved cell viability in cells treated with DEH. Furthermore, DEH also exhibited significant anticancer activities in the CDX- and PDX-models. Conclusions Collectively, our studies strongly suggest that DEH might be a potential anticancer agent against colorectal cancer by activating ER stress-induced inhibition of autophagy.

scholarly journals Assessment of Acid Phosphatase Production by In vitro Cultures of Atropa acuminata

2016 ◽  
Vol 26 (1) ◽  
pp. 15-23
Author(s):  
Saima Khan ◽  
Meenu Katoch ◽  
Sharada Mallubhotla ◽  
Suphla Gupta ◽  
Manju Sambyal ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Growth Period ◽  
Callus Cultures ◽  
Shoot Cultures ◽  
Crude Enzyme Extract ◽  
Atropa Acuminata

The potential of various culture lines of Atropa acuminata were investigated for resourcing acid phosphatase (ACP) (3.1.3.2). Crude enzyme extract comprised of a mixture of four isoforms, distinguishable by polyacrylamide gel electrophoresis (PAGE) with molecular weight ranging from 39 to 215 kDa. In vitro regenerated proliferative shoots, callus and roots showed higher specific activity (2.49, 3.41, 2.91 U/mg protein, respectively) as compared to in vivo grown plants (0.71 U/mg protein). ACP activity in root cultures increased progressively up to 4.6 U/mg during the entire growth period (2 ? 24 weeks), whereas in case of shoot cultures, the specific activity escalated to 2.49 U/mg at 8 weeks, which then declined subsequently (1.95 U/mg). Similarly, callus cultures initially showed a higher phosphohydrolytic activity (3.41 U/mg protein) until 8 weeks by which period, it decreased with the passage of growth period. The present studies reveal an alternate system for resourcing of ACP from Atropa acuminata.Plant Tissue Cult. & Biotech. 26(1): 15-23, 2016 (June)

Sign in / Sign up

Export Citation Format

Share Document