BIOSYNTHESIS OF LECITHIN IN. BRAIN AND DEGENERATING NERVE. PARTICIPATION OF CYTIDINE DIPHOSPHATE CHOLINE

1957 ◽  
Vol 35 (1) ◽  
pp. 945-951 ◽  
Author(s):  
R. J. Rossiter ◽  
I. M. McLeod ◽  
K. P. Strickland
Keyword(s):  
Sciatic Nerve ◽  
Metabolic Pathways ◽  
Phosphatidyl Ethanolamine ◽  
Phosphatidyl Serine ◽  
Two Dimensional ◽  
Naturally Occurring ◽  
Hydrolysis Products ◽  
Cytidine Diphosphate

The radioactivity of cytidine diphosphate choline labelled with P32(CMP-P32Ch) was incorporated in vitro into the phosphatides of both hypotonic homogenates of rat brain and mitochondria prepared from isotonic sucrose homogenates. With both preparations the incorporation was increased by addition of D-α,β-diglycerides prepared enzymatically from naturally-occurring lecithins.Hydrolysis of the labelled phosphatides, followed by separation of the hydrolysis products by two-dimensional paper chromatography, indicated that most of the radioactivity was in lecithin (phosphatidyl choline). Only traces of activity were present in phosphatidyl ethanolamine and phosphatidyl serine. There was also some radioactivity in an alkali-stable fraction that was designated 'sphingomyelin'.These findings are consistent with the view that the phosphatides of brain are formed in situ from smaller molecules and that the metabolic pathways for their formation are similar to those postulated by Kennedy and colleagues for the biosynthesis of phosphatides in chicken liver.The radioactivity of CMP-P32Ch also was incorporated into the phosphatides of homogenates of rat sciatic nerve. This incorporation was greater in homogenates prepared from nerves removed 13 days after previous section. It is suggested that these and other increases, found in the in vitro labelling of phosphatides in nerves degenerating after previous section, reported elsewhere, represent an increase in the potentiality of the nerve for remyelination. These increases are associated with the increase in the number of Schwann cells in the nerve.

BIOSYNTHESIS OF LECITHIN IN. BRAIN AND DEGENERATING NERVE. PARTICIPATION OF CYTIDINE DIPHOSPHATE CHOLINE

1957 ◽  
Vol 35 (11) ◽  
pp. 945-951 ◽  
Author(s):  
R. J. Rossiter ◽  
I. M. McLeod ◽  
K. P. Strickland
Keyword(s):  
Sciatic Nerve ◽  
Metabolic Pathways ◽  
Phosphatidyl Ethanolamine ◽  
Phosphatidyl Serine ◽  
Two Dimensional ◽  
Naturally Occurring ◽  
Hydrolysis Products ◽  
Cytidine Diphosphate

The radioactivity of cytidine diphosphate choline labelled with P32(CMP-P32Ch) was incorporated in vitro into the phosphatides of both hypotonic homogenates of rat brain and mitochondria prepared from isotonic sucrose homogenates. With both preparations the incorporation was increased by addition of D-α,β-diglycerides prepared enzymatically from naturally-occurring lecithins.Hydrolysis of the labelled phosphatides, followed by separation of the hydrolysis products by two-dimensional paper chromatography, indicated that most of the radioactivity was in lecithin (phosphatidyl choline). Only traces of activity were present in phosphatidyl ethanolamine and phosphatidyl serine. There was also some radioactivity in an alkali-stable fraction that was designated 'sphingomyelin'.These findings are consistent with the view that the phosphatides of brain are formed in situ from smaller molecules and that the metabolic pathways for their formation are similar to those postulated by Kennedy and colleagues for the biosynthesis of phosphatides in chicken liver.The radioactivity of CMP-P32Ch also was incorporated into the phosphatides of homogenates of rat sciatic nerve. This incorporation was greater in homogenates prepared from nerves removed 13 days after previous section. It is suggested that these and other increases, found in the in vitro labelling of phosphatides in nerves degenerating after previous section, reported elsewhere, represent an increase in the potentiality of the nerve for remyelination. These increases are associated with the increase in the number of Schwann cells in the nerve.

Absorption of beta-casomorphins from autoperfused lamb and piglet small intestine

1990 ◽  
Vol 259 (3) ◽  
pp. G443-G452 ◽  
Author(s):  
L. C. Read ◽  
A. P. Lord ◽  
V. Brantl ◽  
G. Koch
Keyword(s):  
Small Intestine ◽  
Intestinal Lumen ◽  
Physiological Conditions ◽  
Naturally Occurring ◽  
Gut Epithelium ◽  
Measured Absorption ◽  
Beta Casein ◽  
Kinetics Of

beta-Casomorphins (beta-CMs) derived from milk beta-casein may exert various opiate activities in milk-fed infants. To assess the physiological significance of beta-CMs as a source of circulating opioids in infants, we measured absorption rates of several beta-CMs under near-physiological conditions using in situ autoperfused lamb intestine. The naturally occurring beta-CMs, beta-CM-7 and beta-CM-4-amide, were absorbed readily into blood with no transfer into lymph. Uptake peaked within several minutes of the luminal infusion of peptide but then declined sharply and stopped within a further 10-15 min. The recovery in blood, intestinal contents, and tissue at the end of the 30-min experiment was less than 1% of the infused dose. The low recovery was due to rapid proteolysis based on in vitro studies that demonstrated half-lives of less than 5 min in lamb blood, luminal contents, and lymph. The synthetic dipeptidyl peptidase IV-resistant analogue beta-[D-Ala2]CM- 4-amide was stable during incubation in blood, lymph, or luminal contents and was absorbed into blood at rates that were maximal within several minutes and remained steady for the 30-min period. We conclude that although natural beta-CMs are transferred across the lamb small intestine, rapid degradation within the intestinal lumen, gut epithelium, and blood would prevent entry into the circulation under normal conditions. Val-beta-CM-7, a putative stable precursor, had similar stability and kinetics of absorption to beta-CM-7, results that exclude Val-beta-CM-7 as a stable precursor for delivery of beta-CMs to the circulation. Essentially identical results to those in lambs were obtained in 7-day-old piglets.

METABOLISM OF EHRLICH ASCITES TUMOR IN VITRO: SUBCELLULAR DISTRIBUTION OF PHOSPHOLIPIDS NEWLY FORMED FROM14C-LABELED PRECURSORS

1966 ◽  
Vol 44 (11) ◽  
pp. 1461-1468 ◽  
Author(s):  
V. Donisch ◽  
R. J. Rossiter
Keyword(s):  
Microsomal Fraction ◽  
Phosphatidyl Ethanolamine ◽  
Lipid Fraction ◽  
Specific Radioactivity ◽  
Phosphatidyl Inositol ◽  
Phosphatidyl Serine ◽  
Ethanolamine Phosphatidyl ◽  
Ehrlich Ascites ◽  
Ethanolamine Plasmalogen

When Ehrlich ascites cells were incubated in a suitable medium containing choline-1,2-14C, ethanolamine-1,2-14C, L-serine-14C, or glycerol-1-14C, radioactivity was recovered from the lipid fraction. With choline-1,2-14C, radioactivity was incorporated into the three choline-containing phospholipids, lecithin, choline plasmalogen, and sphingomyelin. Radioactivity from ethanolamine-1,2-14C was incorporated into phosphatidyl ethanolamine, ethanolamine plasmalogen, choline plasmalogen, and lecithin. Radioactivity from L-serine-14C was incorporated into phosphatidyl serine, serine plasmalogen, and phosphatide acid, with lesser amounts into phosphatidyl ethanolamine, lecithin, ethanolamine plasmalogen, choline plasmalogen, and sphingomyelin. Radioactivity from glycerol-1-14C was incorporated into the glycerophosphatides, phosphatidic acid, lecithin, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, and choline plasmalogen. Radioactivity from this precursor was also incorporated into sphingomyelin.In all instances, radioactivity was recovered from the phosphatides in the nuclear, mitochondrial, and microsomal fractions of the tumor. Usually, the specific radioactivity of the phosphatides in the microsomal fraction exceeded that in the other two subcellular fractions.

scholarly journals Identification of a bacteria-produced benzisoxazole with antibiotic activity against multi-drug resistant Acinetobacter baumannii

2021 ◽  
Author(s):  
Robert W. Deering ◽  
Kristen E. Whalen ◽  
Ivan Alvarez ◽  
Kathryn Daffinee ◽  
Maya Beganovic ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Metabolic Pathways ◽  
Pathogenic Bacteria ◽  
Antibacterial Agents ◽  
De Novo ◽  
Drug Resistant ◽  
Antibacterial Effects ◽  
Naturally Occurring ◽  
Molecular Modeling Studies

AbstractThe emergence of multi-drug resistant pathogenic bacteria represents a serious and growing threat to national healthcare systems. Most pressing is an immediate need for the development of novel antibacterial agents to treat Gram-negative multi-drug resistant infections, including the opportunistic, hospital-derived pathogen, Acinetobacter baumannii. Herein we report a naturally occurring 1,2-benzisoxazole with minimum inhibitory concentrations as low as 6.25 μg ml−1 against clinical strains of multi-drug resistant A. baumannii and investigate its possible mechanisms of action. This molecule represents a new chemotype for antibacterial agents against A. baumannii and is easily accessed in two steps via de novo synthesis. In vitro testing of structural analogs suggest that the natural compound may already be optimized for activity against this pathogen. Our results demonstrate that supplementation of 4-hydroxybenzoate in minimal media was able to reverse 1,2-benzisoxazole’s antibacterial effects in A. baumannii. A search of metabolic pathways involving 4-hydroxybenzoate coupled with molecular modeling studies implicates two enzymes, chorismate pyruvate-lyase and 4-hydroxybenzoate octaprenyltransferase, as promising leads for the target of 3,6-dihydroxy-1,2-benzisoxazole.

scholarly journals Tripropeptin C Blocks the Lipid Cycle of Cell Wall Biosynthesis by Complex Formation with Undecaprenyl Pyrophosphate

2011 ◽  
Vol 55 (8) ◽  
pp. 3821-3828 ◽  
Author(s):  
Hideki Hashizume ◽  
Ryuichi Sawa ◽  
Shigeko Harada ◽  
Masayuki Igarashi ◽  
Hayamitsu Adachi ◽  
...  
Keyword(s):  
Enzymatic Reaction ◽  
Direct Interaction ◽  
Chromatography Analysis ◽  
Peptidoglycan Synthesis ◽  
Naturally Occurring ◽  
Vancomycin Resistant ◽  
Layer Chromatography ◽  
Related Compounds

ABSTRACTTripropeptin C (TPPC) is a naturally occurring cyclic lipodepsipeptide antibiotic produced by aLysobactersp. TPPC exhibits potent antibacterial activity against methicillin-resistantStaphylococcus aureus(MRSA), vancomycin-resistant enterococci (VRE), and penicillin-resistantStreptococcus pneumoniae. This antibiotic also inhibits the incorporation ofN-acetylglucosamine into the peptidoglycan ofS. aureusat a 50% inhibitory concentration (IC50) of 0.7 μM, which is proportional to its MIC (0.87 μM; equivalent to 1.0 μg/ml). Treatment of exponential-phaseS. aureuscells with TPPC resulted in accumulation of UDP-MurNAc-pentapeptide in the cytoplasm. The antimicrobial activity of TPPC was weakened by the addition of prenyl pyrophosphates but not by prenyl phosphates, UDP-linked sugars, or the pentapeptide of peptidoglycan. The direct interaction between TPPC and undecaprenyl pyrophosphate (C55-PP) was observed by mass spectrometry and thin-layer chromatography analysis, indicating that TPPC can potentially inhibit C55-PP phosphatase activity, which plays a crucial role in the lipid cycle of peptidoglycan synthesis. As expected, TPPC inhibits this enzymatic reaction at an IC50of 0.03 to 0.1 μMin vitro, as does bacitracin. From the analysis of accumulation of lipid carrier-related compounds, TPPC was found to cause the accumulation of C55-PPin situ, leading to the accumulation of a glycine-containing lipid intermediate. This suggested that the TPPC/C55-PP complex also inhibits the transglycosylation step or flippase activity, adding to the inhibition of C55-PP dephosphorylation. This mode of action is different from that of currently available drugs such as vancomycin, daptomycin, and bacitracin.

scholarly journals Sickled erythrocytes accelerate clotting in vitro: an effect of abnormal membrane lipid asymmetry

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 398-401 ◽  
Author(s):  
D Chiu ◽  
B Lubin ◽  
B Roelofsen ◽  
LL van Deenen
Keyword(s):  
Phosphatidyl Ethanolamine ◽  
Phospholipid Composition ◽  
Coagulation Factors ◽  
Phosphatidyl Serine ◽  
Membrane Lipid ◽  
Clotting Time ◽  
Blood Coagulation Factors ◽  
Intact Cells ◽  
Lipid Asymmetry

Abstract A membrane lipid abnormality induced by sickling and found as a permanent alteration in the irreversibly sickled cell (ISC) is the rearrangement of phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) from the inner to the exterior side of the lipid bilayer. Since PS can provide a catalytic surface for the binding of blood coagulation factors and thus can exhibit procoagulant activity, we investigated the influence of oxy and deoxy reversibly sickled cells (RSC) ass well as ISC on clotting in vitro. Red blood cells (RBC), as the source of phospholipid, were added to platelet-poor citrated plasma containing Russell's viper venom (RVV) and clotting time was measured after recalcification. The clotting time after addition of normal RBC and oxy- RSC was similar to the saline blank (100 sec). In contrast, both oxy- ISC and deoxy completely sickled RSC shortened clotting time by 30%. Using liposomes prepared with identical phospholipid composition to the outer lipid leaflet of either normal RBC, RSC or ISC clotting times similar to those with intact cells were achieved. Since the liposomes did not contain protein, accentuation of clotting appears to be related to abnormal phospholipid organization, in particular to the abnormal exposure to aminophospholipids on the outer surface of the membrane. This abnormality may contribute to the pathogenesis of the vaso- occlusive episode in sickle cell anemia.

scholarly journals Sickled erythrocytes accelerate clotting in vitro: an effect of abnormal membrane lipid asymmetry

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 398-401 ◽  
Author(s):  
D Chiu ◽  
B Lubin ◽  
B Roelofsen ◽  
LL van Deenen
Keyword(s):  
Phosphatidyl Ethanolamine ◽  
Phospholipid Composition ◽  
Coagulation Factors ◽  
Phosphatidyl Serine ◽  
Membrane Lipid ◽  
Clotting Time ◽  
Blood Coagulation Factors ◽  
Intact Cells ◽  
Lipid Asymmetry

A membrane lipid abnormality induced by sickling and found as a permanent alteration in the irreversibly sickled cell (ISC) is the rearrangement of phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) from the inner to the exterior side of the lipid bilayer. Since PS can provide a catalytic surface for the binding of blood coagulation factors and thus can exhibit procoagulant activity, we investigated the influence of oxy and deoxy reversibly sickled cells (RSC) ass well as ISC on clotting in vitro. Red blood cells (RBC), as the source of phospholipid, were added to platelet-poor citrated plasma containing Russell's viper venom (RVV) and clotting time was measured after recalcification. The clotting time after addition of normal RBC and oxy- RSC was similar to the saline blank (100 sec). In contrast, both oxy- ISC and deoxy completely sickled RSC shortened clotting time by 30%. Using liposomes prepared with identical phospholipid composition to the outer lipid leaflet of either normal RBC, RSC or ISC clotting times similar to those with intact cells were achieved. Since the liposomes did not contain protein, accentuation of clotting appears to be related to abnormal phospholipid organization, in particular to the abnormal exposure to aminophospholipids on the outer surface of the membrane. This abnormality may contribute to the pathogenesis of the vaso- occlusive episode in sickle cell anemia.

Activity of Synthetic Phospholipids in Blood Coagulation

1965 ◽  
Vol 13 (01) ◽  
pp. 194-217 ◽  
Author(s):  
F. J. M Daemen ◽  
C van Arkel ◽  
H Ch. Hart ◽  
C van der Drift ◽  
L. L. M van Deenen
Keyword(s):  
Blood Coagulation ◽  
Phosphatidyl Ethanolamine ◽  
Phosphatidyl Serine ◽  
Maximum Activity ◽  
Fatty Acid Constituent ◽  
Coagulant Activity ◽  
Negative Surface ◽  
High Concentrations ◽  
Poly Unsaturated Fatty Acid

Summary1. An investigation was made into the activity of synthetic phospholipids on blood coagulation in vitro, utilizing synthetic substances including phosphatidyl ethanolamine and phosphatidyl serine containing a poly-unsaturated fatty acid constituent.2. Applying a one-stage recalcification test, phosphatidyl serine was found to act at high concentrations as anticoagulant. No clot-promoting activity was observed after addition of individual phospholipids. However, several combinations of phospholipids, e.g. phosphatidyl ethanolamine with phosphatidyl serine or certain mixtures of lecithin with phosphatidylserine, shortened the clotting time.3. In the thromboplastin generation test phosphatidyl ethanolamine exhibited some acceleratory activity without being able, however, to replace crude brain cephalin completely. However, optimal coagulant activity was produced by mixtures of synthetic phospholipids viz, phosphatidyl ethanolamine with phosphatidyl serine, phosphatidic acid or (isolated) cardiolipin and by certain combinations of lecithin and phosphatidyl serine.4. In both assay systems the maximum activity of each phospholipid combination was found to be related within certain limits to the ratio of both compounds. It is concluded that the coagulant activity of phospholipids in vitro is not to be attributed to a certain type of phospholipid or a defined mixture. The results obtained with the synthetic compounds appear to support the view that a particular negative surface charge of the phospholipid micelles is a prerequisite for maximal clot-promoting activity of phospholipids.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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