Comparative efficacy of various routes of administration of thymopentin (TP-5) with consideration of degradative mechanisms

Thymopoietin (originally termed TP-5 and now called thymopentin) is a synthetic pentapeptide that can reproduce the biological activity of the 49 amino acid thymic hormone thymopoietin. The efficacy of various routes of administration of thymopentin was studied in mice and guinea pigs using an electromyographic assay as an end point to determine biological activity. In mice, the threshold dose necessary for a significant response when compared to controls was 0.03 mg/kg (mpk) for i.v. (intravenous) injection and 0.3 mpk for both i.p. (intraperitoneal) and s.c. (subcutaneous) injection. For the guinea pig, 0.03 mpk produced a significant response when compared to controls when injected either i.v. or s.c.; 0.3 mpk was required for a significant response for i.n. (intranasal) administration and 0.6 mpk for i.p. injection. When saline or plasma was injected, it produced no change in the electromyographic response. In plasma the pentapeptide is rapidly degraded by proteolytic enzymes. Treatment of plasma with specific enzyme inhibitors followed by incubation with thymopentin or thymopoietin confirmed that serine protease and aminopeptidase M-like enzymes are responsible for the rapid inactivation of thymopentin in plasma, as measured by the electromyographic response.     

The estradiol-stimulated lipoprotein receptor of rat liver. A binding site that membrane mediates the uptake of rat lipoproteins containing apoproteins B and E

Hepatic catabolism of lipoproteins containing apolipoproteins B or E is enhanced in rats treated with pharmacologic doses of 17 alpha-ethinyl estradiol. Liver membranes prepared from these rats exhibit an increased number of receptor sites that bind 125I-labeled human low density lipoproteins (LDL) in vitro. In the present studies, this estradiol-stimulated hepatic receptor was shown to recognize the following rat lipoproteins: LDL, very low density lipoproteins obtained from liver perfusates (hepatic VLDL), and VLDL-remnants prepared by intravenous injection of hepatic VLDL into functionally eviscerated rats. The receptor also recognized synthetic lamellar complexes of lecithin and rat apoprotein E as well as canine high density lipoproteins containing apoprotein E (apo E-HDLc). It did not recognize human HDL or rat HDL deficient in apoprotein E. Much smaller amounts of this high affinity binding site were also found on liver membranes from untreated rats, the number of such sites increasing more than 10-fold after the animals were treated with estradiol. Each of the rat lipoproteins recognized by this receptor was taken up more rapidly by perfused livers from estrogen-treated rats. In addition, enrichment of hepatic VLDL with C-apoproteins lowered the ability of these lipoproteins to bind to the estradiol-stimulated receptor and diminished their rate of uptake by the perfused liver of estrogen-treated rats, just as it did in normal rats. The current data indicate that under the influence of pharmacologic doses of estradiol the liver of the rat contains increased amounts of a functional lipoprotein receptor that binds lipoproteins containing apoproteins B and E. This hepatic lipoprotein receptor appears to mediate the uptake and degradation of lipoproteins by the normal liver as well as the liver of estradiol-treated rats. The hepatic receptor bears a close functional resemblance to the LDL receptor previously characterized on extrahepatic cells.     

Functional effects of thymopoietin32-36 (TP5) on cytotoxic lymphocyte precursor units (CLP-U). I. Enhancement of splenic CLP-U in vitro and in vivo after suboptimal antigenic stimulation

Cytotoxic lymphocyte precursor units (CLP-U) were enumerated in the spleens of C57BL/6 mice 3 days after i.p. injections of synthetic thymopoietin32-36 (TP5). One hundred to 1000 ng TP5/mouse potentiated splenic CLP-U, this effect being detectable only after suboptimal allogeneic sensitization (with 1.2 x 10(5) mitomycin-C treated DBA cells). This elevation of CLP-U persisted in the injected mice for at least 14 days. Control peptide did not affect CLP-U. In vitro incubation of 0.01 to 0.1 ng/ml of TP5 with normal C57BL/6 spleen cells also enhanced CLP-U after suboptimal allogeneic stimulation; high concentrations of TP5 caused suppression of CLP-U and this was detectable with optimal sensitization conditions. Thus TP5, in vitro and in vivo, appears to regulate immune responsiveness and this regulation varies with TP5 dosage and with the immune stimulus.     

Reconstituted low density lipoprotein: A vehicle for the delivery of hydrophobic fluorescent probes to cells

Previous studies have shown that the cholesteryl ester core of plasma low density lipoprotein (LDL) can be extracted with heptane and replaced with a variety of hydrophobic molecules. In the present report we use this reconstitution technique to incorporate two fluorescent probes, 3-pyrenemethyl-23, 24-dinor-5-cholen-22-oate-3β-yl oleate (PMCA oleate) and dioleyl fluorescein, into heptane-extracted LDL. Both fluorescent lipoprotein preparations were shown to be useful probes for visualizing the receptor-mediated endocytosis of LDL in cultured human fibroblasts. When normal fibroblasts were incubated at 37°C with either of the fluorescent LDL preparations, fluorescent granules accumulated in the perinuclear region of the cell. In contrast, fibroblasts from patients with the homozygous form of familial hypercholesterolemia (FH) that lack functional LDL receptors did not accumulate visible fluorescent granules when incubated with the fluorescent reconstituted LDL. A fluorescence-activated cell sorter was used to quantify the fluorescence intensity of individual cells that had been incubated with LDL reconstituted with dioleyl fluorescein. With this technique a population of normal fibroblasts could be distinguished from a population of FH fibroblasts. The current studies demonstrate the feasibility of using fluorescent reconstituted LDL in conjunction with the cell sorter to isolate mutant cells lacking functional LDL receptors.     

Karyotype analysis of Meloidogyne hapla by 3-D reconstruction of synaptonemal complexes from electron microscopy of serial sections

Meloidogyne hapla Race A (meiotic, n=17) females have 17 synaptonemal complexes (SC). The karyotype length is constant throughout pachytene, although nuclear volume increases as pachytene progresses. Each SC has at least one region in which two pairs of lateral elements run parallel to each other for a distance of 1–2 m, thus forming a double SC (dSC). Decondensed chromatin regions (DCR) occur along some SCs and represent 5% of the length of the karyotype. The DCRs may be the location of the sex-determining chromatin. Spermatocytes from males of the same meiotic parthenogenetic race (A) have SCs and cylindrical granular complexes (CGC) while males and females from a mitotic (3n=45) parthenogenetic race (B) lack such structures. The CGCs may contribute precursors necessary for the formation of SCs.     

A peptide-like substance from pituitary that acts like morphine. I. Isolation.

A method is described for extraction from bovine pituitary glands of a substance that shows several properties characteristic of opiates. The material inhibits the twitch tension of the electrically stimulated guinea pig longitudinal muscle-myenteric plexus preparation and of the electrically stimulated mouse vas deferens. This inhibition is reversed and blocked by the opiate antagonist naloxone. The extract also inhibits binding of the opiate agonist etorphine and the opiate antagonist naloxone to stereospecific binding sites in synaptic membranes of guinea pig brain. The inhibition of naloxone binding is decreased by Na⁺ in the manner characteristic of opiate agonists. The physiologic role of the pituitary opioid remains to be investigated.     

A peptide-like substance from pituitary that acts like morphine. 2. Purification and properties.

We have demonstrated the existence of a peptide-like opioid in bovine and porcine pituitary, and determined some of its properties. It is an opioid agonist on the guinea pig myenteric plexus-longitudinal muscle preparation, and on the mouse vas deferens, and it binds to opiate receptors in homogenates of guinea pig brain. Its physiologic role and its possible presence in hypothalamic or other brain regions remain to be determined.     

Do disorders of movement cause movement disorders and dementia?

Neurons require long-distance microtubule-based transport systems to ferry vital cellular cargoes and signals between cell bodies and axonal or dendritic terminals. Considerable progress has been made on developing a molecular understanding of these processes and how they are integrated into normal neuronal functions. Recent work also suggests that these transport systems may fail early in the pathogenesis of a number of neurodegenerative diseases.