Biomedical subjects

P Edman

Publications and source records attributed to P Edman.

At least 37 records · Page 2Linked to original sources

PubMed1985

Biodegradable microspheres II: Immune response to a heterologous and an autologous protein entrapped in polyacryl starch microparticles.

Human serum albumin (HSA) and mouse serum albumin were entrapped in biodegradable microparticles of polyacrylstarch. When HSA entrapped in microparticles was injected i.v. in Balb/c mice a dose-dependent immune response was elicited. No detectable response was obtained when mouse serum albumin entrapped in microparticles was given to the mice. Neither was any response detected when free HSA or free HSA in combination with empty microparticles were injected, as measured by indirect plaque-forming cells in the spleen and serum antibody titers. The immune response to entrapped HSA had a long duration and was mainly T-cell-dependent as athymic nude mice (Nu/Nu) only generated a weak immune response upon injection of the particle entrapped antigen.

Animals↗

PubMed1984

Ultrastructural alterations in macrophages after phagocytosis of acrylic microspheres.

The effect of microparticles on the survival of cultured mouse peritoneal macrophages was investigated using doses of 0.01-0.1 mg of lyophilized particles/ml of medium and 5 X 10(5) cells, corresponding to approximately 4000-40,000 particles per cell. The lowest dose did not significantly change the survival time as compared with the controls, while approximately 75% of the cells were lost during the first 48 h on exposure to the highest dose. High doses of particles induce cellular damage. The morphology and stability of the lysosomal apparatus was followed with electron microscopy, acid phosphatase cytochemistry, and acridine orange uptake. Alteration of the lysosomal vacuome was characterized by a greatly enhanced rate of autophagocytosis, the formation of huge secondary lysosomes containing microparticles, and labilization of the vacuome with loss of acidity and a tendency to leak acid phosphatase into the cell sap.

Acid Phosphatase↗

PubMed1984

Characterization of polyacryl starch microparticles as carriers for proteins and drugs.

Biodegradable microparticles of cross-linked starch (maltodextrin) have been designed as carriers of proteins and low molecular weight drugs in vivo. Methods are presented for the synthesis of acryloyl starch and its polymerization to microparticles. Macromolecules were immobilized in the microparticles in high yields, i.e., up to 40% of the dry weight consisted of the immobilized protein. The optimal conditions of immobilization were investigated by varying the concentration of starch (D), the concentration of acryloyl groups (T), and the amount of additional cross-linking agent (C). Exclusion of the cross-linking agent gave maximal immobilization of the macromolecules. Enzyme kinetics, release profiles, surface localization, and heat stability of the immobilized macromolecules are also presented. Micro-particles based on starch with small amounts of acryloyl groups were completely degraded after incubation with amyloglucosidase. The degradation of microparticles in serum and in the target organelle, the lysosome, was investigated in vitro. The polyacrylic starch microspheres (mean diameter, 0.5 micron) constitute an attractive alternative to other drug and enzyme carriers.

Biotransformation↗

PubMed1984

Biodegradable microspheres. I. Duration of action of dextranase entrapped in polyacrylstarch microparticles in vivo.

Dextranase was entrapped in polyacryl starch microspheres of different compositions by emulsion polymerization. After i.v. injection in mice and rats, the particles were removed from the blood circulation by macrophages of the reticuloendothelial system. In these cells, the particles are accumulated in the lysosomes. The degradation of different 14C-labeled microparticles and their entrapped dextranase was followed in an isolated lysosomal fraction in vitro and in liver and spleen after i.v. injection in mice. The duration of entrapped dextranase in vivo was followed directly, i.e., by an enzyme assay, and indirectly by following the decrease of a stored material, [3H]dextran in the liver. The degradation of the entrapped enzyme was dependent on the composition of the particle matrix. More cross-linked spheres could better protect the entrapped enzyme in vitro and in vivo. The half-life of free dextranase in the lysosomal fraction was estimated to be about 4 hr, whereas the duration of entrapped dextranase in the liver was at least 48 hr, as measured with [3H]dextran. Finally, the effect of entrapped and free dextranase on an artificially induced storage disease was studied. The stored [3H]dextran was eliminated completely when dextranase was used in microparticles, whereas free dextranase had no effect in vivo.

Animals↗

PubMed1983

Acrylic microspheres in vivo VI: antitumor effect of microparticles with immobilized L-asparaginase against 6C3HED lymphoma.

The antitumor effect of immobilized L-asparaginase was tested against lymphoid leukemia in mice with concomitant scanning of the L-asparagine level in serum. L-Asparaginase was immobilized in microspheres of polyacrylamide or polyacryldextran. These particles were used in C3H mice bearing the L-asparagine-dependent lymphoma (6C3HED). The tumor was maintained as an ascites tumor, 1 X 10(6) cells were injected intraperitoneally and on day 4 after inoculation, L-asparaginase was injected intramuscularly or intraperitoneally in microparticles. After injection of 5.0 IU ip of L-asparaginase in microparticles, partial remission was induced, generally, however, the cancer relapsed and killed the mice within 2-3 weeks. To obtain complete regression, it was necessary to inject 20 IU of L-asparaginase in microparticles intraperitoneally. The best therapeutic effect was obtained when the particles were administered intramuscularly. After injection of 5 IU the survival time was prolonged, but complete regression was not achieved. The best effect was obtained when the particles were given intramuscularly in two small doses (2.5 IU) at a 3-day interval. Such treatment induced complete regression; 10 out of 12 treated mice were completely cured and lived for several months. It is concluded that the L-asparagine level in serum has to be depressed to less than 20% of the normal level for at least 6-7 days to obtain complete regression of the tumor.

Acrylates↗

PubMed1983

Acrylic microspheres in vivo VII: morphological studies on mice and cultured macrophages.

Intravenously injected microparticles of polyacrylamide were cleared from the circulatory system in mice predominantly in liver, spleen, and bone marrow in mice by macrophages belonging to the reticuloendothelial system. In these cells, particles were found in dilated secondary lysosomes. The lysosomotropic character of the particles was further demonstrated using cultured peritoneal mouse macrophages. Histological changes of the liver, spleen, and bone marrow detectable by light and electron microscopy could only be seen after administration of massive doses of microparticles corresponding to 160 mg/kg body weight. In such cases, a medium-coarse vacuolization of liver parenchymal cells could be seen 1-2 days after particle administration. After 3-5 days, degeneration and necrotic cellular alteration occurred in the liver, spleen, and bone marrow. One week after particle administration, regeneration started under formation of granulomas which replaced the necrotic areas. The tissues later became normalized (after 2-3 weeks), but small granulomas remained for several weeks. The damage was parallelled by changes in the liver and spleen weights. Electron microscopy of the liver revealed that the initiated vacuolization of the parenchymal cells was due to mitochondrial swelling with rupture of the mitochondrial cristae.

Acrylates↗

PubMed1983

Acrylic microspheres in vivo VIII: distribution and elimination of polyacryldextran particles in mice.

The disposition of different 14C-labeled, biodegradable polyacryldextran microparticles after intravenous injection has been studied in the mouse. The particles were rapidly cleared from the circulatory system by the reticuloendothelial system. They were predominantly (60-80%) found in the liver and spleen and to some extent in the bone marrow. Large particle aggregates were found in the lungs 6 hr postinjection. After redistribution, the particles were eliminated from the organs with an apparent t 1/2 of 12-30 weeks, depending on the composition of the particles. Highly cross-linked particles with 2% acrylic groups (DTC = 11-2-75) had a half-life similar to that of polyacrylamide particles (TC = 8-25). The metabolism rate was also correlated with the degradation in vitro with isolated rat lysosomes. After intravenous injection of small 14C-labeled polyacrylamide particles (0.2-0.5 micron), significant amounts of radioactivity were detected in the bile and gallbladder.

Acrylic Resins↗

PubMed1983

Acrylic microspheres in vivo IX: Blood elimination kinetics and organ distribution of microparticles with different surface characteristics.

The elimination of microparticles from blood after intravenous injection is dependent on the surface characteristics of the particles. The half-life in blood increases from 44 to 84 min after modification of surface-localized human serum albumin with polyethylene glycol. Irrespective of the surface properties, particles are localized in the reticuloendothelial system, mainly in the liver and spleen. In preimmunized mice, the distribution of particles is somewhat altered, i.e., the liver and lung uptake is significantly higher in preimmunized animals than in untreated animals. The rate of phagocytosis of particles with different surface characteristics has also been studied in vitro with isolated mouse peritoneal macrophages. This technique gives a good correlation with the in vivo results; thus particles with a short half-life in mice are rapidly phagocytosed by the macrophages in vitro.

Acrylamides↗

PubMed1983

Determination of the degree of derivatization of acryloylated polysaccharides by Fourier transform proton NMR spectroscopy.

Dextran, glycogen, hydroxyethyl starch, and maltodextrin were derivatized with acrylic acid glycidyl ester at alkaline pH. The degree of derivatization was determined by water-elimination Fourier transform nuclear magnetic resonance (NMR) and compared with a bromination method. The signals from the anomeric protons of the glucose residues were used as an internal standard and the degree of derivatization was obtained from the relation between the integrated signals from the acrylic and anomeric protons. The NMR technique is shown to be more precise and convenient for the determination of acryloyl groups than the bromination method used.

Acrylates↗

PubMed1983

Induced autophagocytosis in macrophages. Origin of the segregating membranes.

Cultured mouse peritoneal macrophages were exposed for 48 h to a large and toxic dose of polyacrylamide microspheres (previously designed for use as a lysosomotropic carrier for the intracellular delivery of enzymes and other macromolecules). This treatment induced autophagocytosis in the macrophages, which contained abundant autophagic vacuoles at 24 h post exposure. Transmission electron microscopical studies including enzyme cytochemistry showed that the segregating membranes in autophagosome formation consisted of flattened, smooth-surfaced vacuoles with a granular matrix in which reaction product indicating acid phosphatase activity could be demonstrated. The autophagic vacuole formation was apparently effected by wrapping of a portion of the cytoplasm in a sheet formed by flattening and fusion of multiple small vacuoles with acid phosphatase activity in their matrices. The conclusion is drawn that the segregating membranes are derived from lysosomes or GERL structures in this particular system of induced autophagocytosis.

Acrylic Resins↗

PubMed1983

Use of immobilized L-asparaginase in acrylic microparticles in an extracorporeal hollow-fiber dialyzer.

L-asparaginase was immobilized under aseptic conditions in spherical microparticles of polyacrylamide. To avoid direct contact between blood and enzyme, we have applied the immobilized L-asparaginase in microparticles on the outer surface of the capillary fibers of a hemofilter. The hemofilters were very efficient in the transformation of L-asparagine to L-aspartic acid, both in vitro and in vivo. L-Asparagine in buffer (50 microM in 5 liters) was converted to L-aspartic acid within 60 min after circulation through a hemofilter containing 2000 I.U. of L-asparaginase. Circulating L-asparagine in healthy sheep (about 40-50 microM was reduced to low levels after 2 to 3 hr of perfusion with a unit containing 2000 I.U. of L-asparaginase. The reduction persisted for 3 to 4 hr after terminated treatment. Repeated, extracorporeal treatments in sheep showed that the L-asparagine decrease induced an increased resynthesis of L-asparagine, probably due to the action of the L-asparagine synthetase.

Acrylic Resins↗

PubMed1982

Treatment of artificially induced storage disease with lysosomotropic microparticles.

An artificial storage disease has been induced in mice by intravenously injecting 14C-labelled crosslinked dextran. The dextran was essentially taken up in the spleen and liver by cells belonging to the reticuloendothelial system and stored there in the lysosomes. Soluble dextranase, when given intravenously, had no effect on the stored dextran as judged by the radioactivity content of the tissues. However, when the dextranase was immobilized in microparticles of polyacryldextran and injected intravenously, the clearance of the radiolabelled dextran was significantly catalyzed. The lysosomotropic microparticles carried the enzyme to the lysosomes, where the microparticles were destroyed by the dextranase, which thereafter digested the stored 14C-dextran. The results illustrate the use of "self-destroying" microparticles as a lysosome-directed carrier of enzymes.

Acrylic Resins↗

PubMed1982

Acrylic microspheres in vivo V: Immunological properties of immobilized asparaginase in microparticles.

L-Asparaginase was immobilized in microparticles of polyacrylamide. Such particles were then injected by intramuscular/subcutaneous, intraperitoneal, or intravenous routes into mice to investigate the immunological consequences of the immobilization. Entrapment of L-asparaginase in microparticles did not prevent the formation of antibodies in intensively treated animals. Intraperitoneal and intravenous injections of particles produced significantly higher antibody levels than soluble L-asparaginase. Antigen administered intramuscularly/subcutaneously in microparticles elicited, however, a weak immune response. Dependent on the route of administration, the particles may thus function as an adjuvant. A modified Arthus reaction in the foot pads of immunized mice indicated that antigenicity decreased when L-asparaginase was immobilized in microparticles. Injection of free L-asparaginase, intramuscularly/subcutaneously (2 x 20 IU) in the preimmunized mice produced no effects on the serum level of L-asparagine, whereas intramuscular/subcutaneous injection of L-asparaginase in microparticles produced a depression of the serum concentration. It is concluded that the intramuscular/subcutaneous injection of L-asparaginase in microparticles is the choice route of administration with respect to duration and the immunological reaction.

Animals↗

PubMed1981

Prolongation of effect of asparaginase by implantation in polyacrylamide in rats.

Asparaginase was immobilized in spherical polyacrylamide microparticles, which were inserted in polyacrylamide gel for implantation in rats. Intraperitoneal implantation of this gel depressed systemic L-asparagine for the same duration as was achieved with microparticles, i.e., 8-10 days. The duration of the effect was prolonged up to about 25 days when the gel with the enzyme was implanted subcutaneously on the back of the rat. In both cases, a collagenous capsule formed around the gel, eventually preventing contact with the circulation. The effect of a second implantation was of the same magnitude as the first one.

Acrylic Resins↗

PubMed1980

Immobilization of proteins in microspheres of biodegradable polyacryldextran.

Macromolecules were immobilized by an emulsion polymerization technique in biodegradable microspheres of polyacryldextran, prepared by copolymerizing bisacrylamide with acryldextran. Such particles can be characterized by D-T-C expressions, where D denotes the concentration of derivatized dextran, T is the total concentration of acrylic compounds in the monomeric solution, and C denotes the fraction of cross-linker. In microparticles based on dextran T40 with a D-T-C of 11-1-75, the yield of immobilized protein was greater than in polyacrylamide particles. The properties of the immobilized proteins, e.g., Km and Vmax, were retained. The heat stability of the proteins was improved so that 5--10% of carbonic anhydrase still was active after 30 min at 100 degrees. However, the leakage of proteins from the polyacryldextran particles was greater than from polyacrylamide particles.

Acrylic Resins↗

PubMed1979

Acrylic microspheres in vivo. I. Distribution and elimination of polyacrylamide microparticles after intravenous and intraperitoneal injection in mouse and rat.

Microspheres of 14C-labeled highly cross-linked polyacrylamide (mean diameter 0.25-0.30 micron) have been prepared by emulsion polymerization. The label was introduced in the polymer via the cross-linking monomer. N,N'-[14C]methylenebisacrylamide. The microparticles were used to follow qualitatively and quantitatively the distribution and the fate of polyacrylamide in mouse and rat after i.v. and i.p. injection. The polyacrylamide particles are rapidly cleared from the circulation (t 1/2 in rat approximately 40 min) by macrophages of the reticuloendothelial system. They are mainly (about 80%) found in the liver and spleen both after i.v. and i.p. injection (4.1 mg given totally to mice weighing 20-25 g). They can also be detected early (1 hr after i.v. injection) in the bone marrow, and particle aggregates are also initially found in the lungs, although no respiratory problems were noted. After about 16 weeks, the radioactivity rapidly decreases in the liver and spleen, with t 1/2 10 to 14 weeks and 15 to 24 weeks, respectively, depending on the route of administration. Radioactivity in the gut and gut walls detected 2 months after injection suggests that the polyacrylamide is slowly metabolized. No toxic effects-apart from transient hepatospleenomegaly-were detected in mice 45 weeks after they were given a total of 9.8 mg of polyacrylamide.

Acrylamides↗

PubMed1979

Acrylic microspheres in vivo. II. The effect in rat of L-asparaginase given in microparticles of polyacrylamide.

L-Asparaginase was immobilized in spherical microparticles of polyacrylamide. Particles of three different sizes, mean diameter 0.34, 18 and 36 micron, respectively, were used. The Michaelis constant Km, for L-asparaginase, immobilized in small particles (0.34 micron), is virtually the same as in solution. L-Asparaginase in microparticles was also more stable than free enzyme after storage for 140 days at +4 and +37 degrees C. After an i.v. injection of 200 I.U./kg into rat, the plasma L-asparagine fell to very low values (less than 10 nmol/ml), but was normalized again after 4 to 5 days with both the native and immobilized enzymes. After an i.p. injection of 1000 I.U./kg into rats, the microparticles containing L-asparaginase lowered the plasma L-asparagine level for a substantially longer period of time than L-asparaginase in free solution. Normal L-asparagine level was thus reached on day 14 after the injection with immobilized enzyme. However, L-asparaginase activity was still present in the abdominal lymph nodes after this period of time.

Acrylamides↗

PubMed1976

Abnormal behaviour of proline in the isothiocyanate degradation.

It has been observed that proline residues often initiate overlaps during sequenator analysis. The cause has been shown to be an abnormally slow cleavage reaction. The kinetics of the cleavage reaction has been studied and found to obey pseudo-first-order kinetics. There are considerable differences in reaction rates depending on the position of proline in the sequence, as demonstrated for the four prolines in the N-terminal section of the H2B histone from chicken.

Amino Acid Sequence↗