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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly(DL-lactic acid) [DL-PLA] microcapsules containing phenobarbitone (PB) were prepared using a w/o emulsion-evaporation method. DL-PLA of three different molecular weights, 20,200, 13,300 and 5,200 were used to prepare microcapsules of nominal core: polymer (C:P) ratios of 1 : 2, 1 : 2.5, 1 : 3 and 1 : 4. The release of PB was investigated in aqueous buffer of pH 2, pH 7 and pH 9 at 37 degrees C and found to follow a square root of time dependent release mechanism. The first order and zero order release mechanisms were disproved by the lower correlation coefficient of the release data as compared to that of the t1/2 mechanism. These microcapsules showed an initial burst phase release followed by a lag phase, during which time little PB was released. This lag time was affected by the polymer molecular weight and pH of the buffer. The polymer matrix was hydrated during the lag phase and a steady state release occurred. The steady state release rate per unit specific surface area (Kh2/SSA) was found to increase exponentially with the increase in core loading of the microcapsules. However the extent of normalized release rate reduced linearly with the increase in polymer molecular weight at any particular core loading (e.g. 20 per cent or 30 per cent). Increases in the normalized steady state release rate with an increase in buffer pH could be correlated to PB solubility in the dissolution medium. PB release from these microcapsules was diffusion controlled. However, swelling and erosion also contributed to the release process.
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PMID:Microencapsulation using poly(DL-lactic acid). III: Effect of polymer molecular weight on the release kinetics. 238 38

Poly (DL-lactic acid) [DL-PLA] microcapsules containing phenobarbitone were prepared using a W/O emulsion method. Microcapsules of nominal C : P ratio, 1 : 2 and 1 : 3 using three different molecular weight polymers, 20,500, 13,300 and 5,200 were investigated to study the effect of storage conditions on the microcapsule properties. All microcapsules were stored under desiccated condition at temperatures of 4 degrees, 20 degrees and 37 degrees C for six months. Storage temperatures of 4 degrees and 20 degrees C did not cause appreciable changes in the release rate after storage. Microcapsules stored at 37 degrees C showed an annealing effect, causing shrinkage of microcapsules, and lowering of the release rate after storage for six months. The microcapsules prepared from low molecular weight DL-PLA fused completely whilst stored at 37 degrees C and the other two high molecular DL-PLA also showed some aggregation. There were insignificant variations in the mean microcapsule diameter during storage. The phenobarbitone content of the microcapsules was also unchanged.
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PMID:Microencapsulation using poly(DL-lactic acid). IV: Effect of storage on the microcapsule characteristics. 238 39

Four sub-lines (strain A, C, D, E) were isolated from a human lung giant cell carcinoma cell line (PLA-801) by the single cell cloning technique. The incidence of spontaneous metastasis was higher in strain D, moderate in strains A, E and lower in strain C after they were inoculated subcutaneously into the nude mice. The lung and lymph-nodes were the major target organs of metastasis. Morphological studies (light microscope, electron microscope and immunohistochemistry) showed that the cytoplasm of metastatic tumor cells was rich in microfilament and positive for Vimentin. The results strongly support the theory on tumor cell heterogenicity. In addition, these clones, especially strains D and C, could be an ideal model for the study of tumor metastasis.
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PMID:[Spontaneous metastasis of clonal cell subpopulations of human lung giant cell carcinoma after subcutaneous inoculation in nude mice]. 255 Jan 96

In the present study the possible dual effects of adenosine as substrate and adenosine receptor agonist in rat granulosa cells, cumulus-oocyte complexes, luteal cells and ovarian membranes are discussed. Adenosine is an indispensable compound in cell energy metabolism, as precursor to cofactors, second messenger and nucleic acids. Adenosine is also an agonist to adenosine receptors. The adenosine receptor can either inhibit (A1) or stimulate (A2) adenylate cyclase. Alternatively, in some cells adenosine receptor activation is linked to other cellular events like inhibition of Ca2+ fluxes. Adenosine is taken up by isolated preovulatory granulosa and luteal cells from pregnant mare serum gonadotropin-treated immature rats, but follicle stimulating hormone (FSH) decreases the uptake by granulosa cells. Adenosine, but not the non-metabolizable adenosine analogs 5'-(N-ethyl)carboxamide-adenosine (NECA), 2-chloro-adenosine (2-Clado), N6-(R-phenyl-isopropyl)-adenosine (R-PLA) and N6-(S-phenyl-isopropyl)-adenosine (S-PLA), increase granulosa cell ATP levels. FSH and luteinizing hormone (LH) decrease granulosa cell ATP levels in the presence or absence of adenosine. It has previously been shown that FSH and LH decrease oxygen consumption by cumulus-oocyte complexes and increase their lactate production. These effects have been suggested to be due to a competition of cofactors (e.g. ADP) common to glycolysis and the respiratory chain. The fact that adenosine reverse the gonadotropin-induced effects on oxygen consumption and lactate production support this theory. Adenosine and its analogs increase cAMP accumulation in luteal and granulosa cells only in the presence of gonadotropins, and this effect is antagonized by the adenosine receptor antagonist 8-phenyl-theophylline (8-PHT). Furthermore, adenylate cyclase is stimulated by adenosine analogs in membranes from non-luteinized and luteinized ovarian membranes and in luteal cell homogenates. The effect of NECA is antagonized by 8-PHT. In the membranes, the rank order of potency was NECA greater than 2-Clado greater than R-PLA greater than S-PLA, suggesting adenosine A2 receptors. In summary, it is suggested that adenosine can act both as a substrate to intracellular metabolism and as an adenosine A2 receptor agonist in granulosa and luteal cells. A paracrine short loop positive feedback model is proposed where extracellular adenosine, derived from a gonadotropin-induced extracellular increase in cAMP and a decrease in cellular ATP, enhances gonadotropin stimulation in granulosa and luteal cells.
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PMID:Adenosine as substrate and receptor agonist in the ovary. 255

Microcapsules were prepared using a poly (L-lactic acid) (L = PLA), mol. wt. 43,200, by an emulsification and solvent evaporation technique. Phenobarbitone (PB) was used as a reference drug, (core to polymer ratio, 1:1). Both the o/w and w/o emulsion system were investigated in order to study microcapsule properties affected by the preparative technique. In the o/w system, dichloromethane (DCM) was used to dissolve L = PLA and PB and the resulting solution was dispersed in 1 per cent aqueous gelatin solution. Subsequent evaporation of the DCM resulted in the formation of microcapsules. PB was found to be poorly encapsulated within microcapsules from this o/w system. PB content in the microcapsules was found to improve using PB saturated aqueous gelatin solution as the continuum. In the w/o system, acetonitrile (AN) was used as a solvent for L-PLA and PB and light liquid paraffin (LLP), containing 2 per cent w/w Span 40, as the continuous phase. PB loading in the microcapsules was found to be very high from this w/o system. Microcapsules from the o/w system were very small compared to microcapsules obtained from the w/o system. The morphology of the microcapsules and the surface properties were found to be affected distinctly by the two techniques. Microcapsules from the o/w system showed a smooth and less porous surface, whereas a highly porous surface containing embedded PB crystals was found in the microcapsules from the w/o system.
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PMID:Microencapsulation using poly(L-lactic acid). I: Microcapsule properties affected by the preparative technique. 258 39

Examination of 107 patients that had undergone radical correction of tetralogy of Fallot using computer monitoring and mathematical modelling of circulation showed that right-ventricular failure was characterized by reduced cardiac output, high central venous pressure at relatively low left-ventricular pressures, high PV-PLA gradient at low pumping function of the right ventricle. An increase in the volume load in right-ventricular failure may lead to suppressed pumping function of the right heart. Thus, infusion therapy should be administered in relation to the PV-PLA gradient and its changes with increased adrenomimetic doses. Replacing assisted ventilation by spontaneous breathing should be accomplished in these patients using the technique of intermittent forced lung ventilation which is most optimal.
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PMID:[Principles of the diagnosis and intensive therapy of right ventricular insufficiency in patients following radical correction of Fallot's tetralogy]. 259 92

Two phospholipases were found in the venom of Bungarus fasciatus, one in fraction III, the other in fraction X of the chromatographic separation. A neutral PLA2(III) purified from fraction III was subjected to amino acid sequencing by means of an automated sequenator applied to the intact RCM-PLA2 (III) and the individual peptides obtained from HPLC separation of the three types of enzymatic peptides. PLA(III) was shown to consist of 118 amino acid residues with 14 half-cystines. It is 65% homologous to the basic PLA2 obtained from fraction X.
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PMID:Amino acid sequence of a neutral phospholipase A2 (III) in the venom of Bungarus fasciatus. 259 63

Biodegradable pellets intended for either parenteral or oral use were successfully prepared from low molecular weight poly(DL-lactide) (low MW PLA, MW' = 2000) or a relatively high molecular weight poly(L-lactide) (L-PLA, MW = 215,000) sample by a simple direct compression technique without the use of heat or organic solvents. The energy imparted during the compression step caused fusion of the low MW PLA particles. Pellets prepared from low MW PLA swelled considerably before eroding in pH 7.4 buffer, but acted as an enteric matrix in 0.1 M HCl. This was attributed to the high carboxyl endgroup:polymer chain ratio which increased with a decrease in molecular weight. Interactions between salts of basic drugs (quinidine sulfate or propranolol hydrochloride) and the polymeric carboxyl endgroups caused retardation in the drug release from low MW PLA pellets. The drug release from L-PLA pellets was independent of the pH of the dissolution media and drug-polymer interactions were absent. The drug release could be increased by admixing sodium chloride prior to compression, or reduced by dipping the pellets into methylene chloride for a short period of time.
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PMID:Evaluation of biodegradable poly(lactide) pellets prepared by direct compression. 260 Jul 86

1. The major phospholipase A2 (PLA-DE4) of the venom of Trimeresurus purpureomaculatus (shore pit viper) has been purified to electrophoretic homogeneity. 2. The isoelectric point of the purified enzyme was determined to be 4.20, and the mol. wt was 31,700 as estimated by Sephadex G-75 gel filtration chromatography; and 14,000 as estimated by SDS-polyacrylamide gel electrophoresis. The purified enzyme hydrolyzed phosphatidylcholine (PC) faster than phosphatidylethanolamine (PE), whereas phosphatidylserine (PS) was not hydrolyzed at all (PC greater than PE greater than PS =0). However, in reaction system consisted of mixtures of PC and PS, phosphatidylserine was effectively hydrolyzed by the enzyme. 4. The phospholipase A2 exhibited edema-forming activity but not hemolytic, hemorrhagic or anticoagulant activities. It was not lethal to mice at a dosage of 10 micrograms/g by i.v. route.
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PMID:Isolation and characterization of the major phospholipase A2 from the venom of Trimeresurus purpureomaculatus (shore pit viper). 261 28

In a prospective clinical trial, 85 patients with acute pancreatitis, including 50 with acute interstitial-edematous pancreatitis and 35 with necrotizing pancreatitis, were recruited. Serum pancreatic immunoreactive phospholipase A2 (IR-PLA2), serum phospholipase A catalytic activity (CA-PLA), and serum phospholipase A2 catalytic activity (CA-PLA2) were determined daily between day 1 and day 10 after the onset of the disease. The serum course of IR-PLA2 values for patients with acute interstitial-edematous pancreatitis was comparable to that for patients with necrotizing pancreatitis. In contrast, the determination of CA-PLA and of CA-PLA2 specific activity in the serum revealed a high differentiation between patients with interstitial edematous and those with necrotizing pancreatitis. The overall accuracy for differentiating patients with necrotizing pancreatitis from those with the interstitial-edematous type was 79% for CA-PLA and 77% for CA-PLA2 (cut-off level: CA-PLA, 15 U/L, day 1-5; CA-PLA2, 3.5 U/L, day 1-5). Patients with pancreatitis-associated pulmonary complications showed significantly higher CA-PLA and CA-PLA2 values in the serum. This study demonstrates the role of serum catalytic phospholipase A2 in human acute pancreatitis where the development of pancreatic necrosis and pulmonary failure is concerned.
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PMID:Role of phospholipase A2 in human acute pancreatitis. 268 22


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