Lipid microparticles as sustained release system for a GnRH antagonist (Antide).

Lipid microparticles (LMs) as a sustained release system for a gonadotropin release hormone (GnRH) antagonist (Antide) were prepared and evaluated. Antide loaded microparticles (Antide-LMs) were obtained by a cryogenic micronization process starting from two different monoglycerides (glyceryl monobehenate and glyceryl monostearate) and using two different incorporation methods (co-melting and solvent evaporation). Antide-LMs, 2% (w/w) loading, were characterized for drug incorporation by RP-HPLC, particle size by laser diffractometry and surface morphology by scanning electron microscopy. In vitro peptide release and in vitro biological activity were also studied. Serum Antide and testosterone levels, as pharmacodynamic marker, were assessed following subcutaneous administration in rats. Antide-LMs showed a mean diameter of approximately 30 micro m and variable Antide release depending on lipid matrix and incorporation method. In vivo experiments demonstrated that detectable Antide plasma levels were present, in the case of Antide-LMs based on Compritol E ATO obtained by co-melting procedure, for at least 30 days after dosing. Testosterone levels were consistent with prolonged pharmacokinetic profiles. In vitro release of Antide from LMs correlated well with the in vivo release. In conclusion, LMs can sustain the release of Antide for at least 1 month. The levels of the initial 'burst' and the extent of the pharmacodynamic effect can be influenced by the lipid characteristics and by process conditions.

The unusual amino acid triplet Asn-Ile-Cys is a glycosylation consensus site in human alpha-lactalbumin.

Human alpha-lactalbumin has not been described as a glycoprotein, despite the fact that several alpha-lactalbumins of both ruminant and nonruminant species are known to be glycosylated. In all these species the glycosylation site is the 45Asn in the usual triplet 45Asn-Gly/Gln-47Ser. We have found that human alpha-lactalbumin is glycosylated and the glycosylation site has been determined by protein sequencing and mass spectrometry. We report an unusual glycosylation site at 71Asn in the triplet 71Asn-Ile-73Cys, which is conserved in all known alpha-lactalbumins except red-necked wallaby. That a relatively small proportion of the protein is glycosylated (about 1%) may reflect the importance of this region of the protein sequence to the molten globule state of alpha-lactalbumin.

Primary structure of hemocyanin from Palinurus vulgaris.

The primary structure of hemocyanin from the spiny lobster Palinurus vulgaris was determined using a mixture of at least four slightly different subunits. Heterogeneities were observed in 32 (5%) of the positions. The amino acid sequence differs at about 20% of the positions from that of subunit a of Panulirus interruptus hemocyanin.

Pharmacokinetic and Metabolism Study in Healthy Volunteers After Administration of Single Oral Dose of (3)H-alpha-Dihydroergocryptine Mesylate.

This phase I open pharmacokinetic and metabolism study was conducted with six healthy male volunteers who were given 20 mg of (3)H-alpha-dihydroergocryptine in order to evaluate the absorption, plasma time course, and urinary and fecal elimination of total radioactivity. Rapid absorption into the general circulation occurred with an average K(01) of 0.99 plus minus 0.73/h. Peak time(T(max)) was reached in approximately 3 h with an average radioactivity concentration (C(max)) of 8.78 plus minus 5.9 ng eq h/ml. Distribution from the central compartment to the peripheral compartment occurred with a mean rate constant (K(12)) of 0.330 plus minus 0.22/h. Estimations of total clearance (CL) and volume of distribution (Vd) seem strongly affected by the low oral availability (F) of hydrogenated ergots. The rate constant (K(21)) of radioactivity washout from the tissue to the central compartment was 0.250 plus minus 0.130/h. However, plasma radioactivity declined biexponentially with an overall elimination constant (K(10)) of 0.029 to 0.146/h (i.e, half-lives of 23.9--4.75/h). Total radioactivity recovery in urine and feces was good with 82.78 plus minus 6.44% of dose eliminated in feces and 3.01 plus minus 0.65% in urine. The latter concentration was too low to detect metabolites or unchanged drug by radioactivity image scanning. However, the liquid scintillation count of silica gel that had been scraped off the thin layer chromatography (TLC) plates indicated the presence of metabolites in urine. Pharmacodynamically, both supine and standing blood pressure fell significantly within the first 8 h of dosing, yet there were no changes in heart rate. No adverse reactions were reported. In conclusion, the kinetics of (3)H-dihydroergocryptine are very similar to other ergot alkaloids in respect to extensive hepatic metabolism with an elimination half-life of 25 h.

Pharmacokinetics of recombinant human luteinizing hormone after intravenous, intramuscular, and subcutaneous administration in monkeys and comparison with intravenous administration of pituitary human luteinizing hormone.

To assess the pharmacokinetics of recombinant human LH (rhLH) in monkeys, we measured serum LH levels after single iv injection and after single and repeated doses by the im or sc route. A single iv bolus of 400 IU/kg rhLH or pituitary hLH (phLH) in six cynomolgus monkeys resulted in parallel concentration-time curves. The initial and terminal half-lives of rhLH (0.8 and 11 h) were comparable to those of phLH (0.6 and 10 h). The serum levels of phLH were consistently higher due to the fact that the immunological dose of phLH was higher. Administration of increasing iv doses of rhLH (10, 63, and 400 IU/kg) to six monkeys showed that the pharmacokinetics are linear over this dose range. The total clearance for the two higher doses was 0.03 L/h.kg. Systemic bioavailability was 50% after a single sc injection of 400 IU/kg and 61% after a single im injection of the same dose. The peak concentration (180 IU/L) after im injection was reached after 2.7 h. This was higher and sooner than after sc injection (110 IU/L after 5.3 h). The terminal half-life by both routes was similar to that seen after iv injection (11 h). Daily sc or im administration of 63 IU/kg for 7 days confirmed these findings. There was no accumulation of rhLH. Some monkeys developed antibodies, especially after repeated administration. They were excluded from the analysis. No significant local or systemic adverse events occurred.

Isolation of a new ligand-carrying casein fragment from bovine mammary gland microsomes.

Whilst looking for components involved in retinol metabolism in secreting mammary gland cells, a 12 kDa protein was isolated. This protein had bound a ligand with characteristics of retinol. N-Terminal sequencing and amino acid analysis showed that this protein is highly homologous with an alpha-s1-casein fragment. No ligand was found for beta-lactoglobulin, previously thought to be involved in retinol metabolism.

Human milk components cross-reacting with antibodies against bovine beta-lactoglobulin.

The human whey components cross-reacting with antibodies raised against bovine and/or equine beta-lactoglobulin were screened systematically. The milk of six women on a normal diet was collected within 72 h of confinement and whey components were fractionated by high-speed size exclusion chromatography and reversed-phase techniques. The fractions which were immunoreactive in double diffusion experiments with antisera anti-bovine and/or equine beta-lactoglobulin were subsequently purified by native PAGE and then electroblotted on Pro-blott membrane (Western blotting). Pro-blot membranes were stained in parallel with Coomassie and by immunostaining using antibodies against bovine and/or equine beta-lactoglobulin as first antibody solution. The immunoreactive bands were cut out from the membrane and N-terminally sequenced; all the immunoreactive components were clearly identified as human beta-casein or its (mainly tryptic) fragments. The strong antigenic similarity between human beta-casein and beta-lactoglobulin (bovine and equine) might be of immunological importance; it could mean that breast-fed neonates risk being sensitized to beta-lactoglobulin irrespective of the presence of cow's milk in the mother's diet.

Primary structure of hemocyanin subunit c from Panulirus interruptus.

The amino acid sequence of the hemocyanin subunit c from the spiny lobster, Panulirus interruptus, has been determined. The elucidation was mainly based on three digests, with CNBr, trypsin and endoproteinase Glu-C, respectively. Additional evidence was obtained by sequencing of peptides from an endoproteinase Lys-C digest. Subunit c is a polypeptide with 661 amino acid residues and with a carbohydrate group attached to residue 476 in the third domain. No heterogeneity was observed. The degree of identity with subunit a is 59%. Some differences with subunit a are an N-terminal extension of six residues, a one-residue C-terminal extension, and a three-residue deletion. Furthermore, carbohydrate attachment is in a different position, as are most half-cystine residues. Limited trypsinolysis resulted in cleavage at the same site as in subunits a and b.

Crystallization properties and structure of Panulirus interruptus haemocyanin.

Electron-microscopic studies revealed that two types of subunits of Panulirus interruptus haemocyanin crystallize in different ways. Homohexamers of subunit a give close-packed two-dimensional crystals whereas homohexamers of subunit c form open two-dimensional arrays. We applied computer-image analysis to these arrays and studied the differences in crystallization properties by combining the electron-microscopic data with amino acid sequence information and the X-ray diffraction model of subunit a.

The amino-acid sequence of pancreatic ribonuclease from the mole rat Spalax ehrenbergi, chromosomal species 2n = 60.

The amino-acid sequence of pancreatic ribonuclease from the chromosomal species of Spalax ehrenbergi with karyotype 2n = 60 was determined. From the comparison of the sequence with other mammalian sequences we found that Spalax diverged from the myomorph rodent branch before the divergence of the Muridae and the Cricetidae. All myomorph rodent sequences evolved faster than those of other mammals, an effect being most pronounced for the rat sequence. Spalax ribonuclease shares several amino-acid residues with other myomorph rodent species. These are not or only rarely observed outside this rodent suborder. However, there are 6 amino-acid replacements not observed earlier in pancreatic ribonucleases, and 2 other replacements and an insertion of one residue in the variable loop 15-24 are only observed in the enzyme from turtle pancreas.

The relationship between N-terminal sequences and immunological characterization of crustacean hemocyanins.

1. N-terminal amino acid sequences of seven crustacean hemocyanin subunits were determined and compared together with a number of known N-terminal sequences. 2. Within crustacean infraorders, relationships of subunits were established. Relationships based on N-terminal sequences were compared with a classification based on immunological characterization.

Partial amino acid sequence of a hemocyanin subunit from Palinurus vulgaris.

1. Hemocyanin from the spiny lobster Palinurus vulgaris was separated into two fractions, which were designated as subunits a and b. 2. 55% of the amino acid sequence of subunit b has been determined. A comparison with Panulirus interruptus hemocyanins shows 78% sequence identity with subunit a and 56% with subunit c. It has carbohydrate attached to domain one. Two half-cystines have been substituted, indicating that it probably possesses only one disulfide bridge. Heterogeneity has been observed in seven out of 380 positions determined so far. 3. Subunit a is almost identical with subunit b. In contrast to Panulirus interruptus and Panulirus japonicus, Palinurus vulgaris hemocyanin contains no c-type subunit. 4. A position in the tentative evolutionary tree of arthropod hemocyanins based on sequence differences has been assigned to Palinurus vulgaris subunit b.

Origin of the duplicated ribonuclease gene in guinea-pig: comparison of the amino acid sequences with those of two close relatives: capybara and cuis ribonuclease.

The amino acid sequences of the pancreatic ribonuclease from capybara (Hydrochoerus hydrochaeris) and cuis (Galea musteloides) were determined. Both species belong to the same superfamily of the hystricomorph rodents as the guinea-pig. In guinea-pig pancreas two ribonucleases are present as a result of a recent gene duplication, but in capybara and cuis pancreas only one single ribonuclease has been found. A most parsimonious tree of ribonucleases indicates that the gene duplication leading to both guinea-pig ribonucleases occurred before the divergence of guinea-pig from capybara and cuis. This would mean that changes in expression of the ribonuclease genes have occurred in these taxa. Cuis and capybara ribonuclease have no Asn-X-Ser/Thr sequences and are carbohydrate-free proteins. Capybara ribonuclease has leucine at position 114, a position occupied by proline in the cis-configuration in bovine pancreatic ribonuclease.