Parallel studies of His-DTrp-Ala-Trp-DPhe-Lys-NH2 and human pancreatic growth hormone-releasing factor-44-NH2 in rat primary pituitary cell monolayer culture

His-DTrp-Ala-Trp-DPhe-Lys-NH2 (GH-RP-6) is a synthetic hexapeptide that specifically releases GH both in vivo and in vitro in pituitary incubates. In this study, for the first time, GH-RP-6 was studied in primary pituitary cell monolayer culture. Parallel studies were performed with human pancreatic GH-releasing factor-44 (hpGRF-44). Culture conditions optimal for GH-RP-6 were not optimal for hpGRF-44. Both peptides released GH in a dose- and time-dependent manner. In this assay system, the ED50 for GH-RP-6 was 9 nM, and the ED50 for hp-GRF-44 was 1.6 nM. Calcium-blocking agents inhibited the GH responses of both peptides as well as basal GH release. Pretreatment with GH-RP-6 decreased the subsequent response to both GH-RP-6 and hpGRF-44. hpGRF-44 down regulated itself but not GH-RP-6. Rat sera potentiated the GH response of hpGRF-44 but not that of GH-RP-6. GH-RP-6 and hpGRF-44 GH responses were additive. These results suggest that GH-RP-6 and hpGRF-44 stimulate GH release via different somatotroph receptors.

Monoclonal antibody (WI-2) reactive against human transformed and leukemic cells

A monoclonal antibody (WI-2) was produced against HL-60 cells. This antibody was IgM Kappa and reacted with human cell lines derived from fibroblasts and from hemopoetic, lymphoid, and neoplastic tissues. It also reacted with lymphocytes transformed by mitogens. WI-2 lacked reactivity against normal human RBC's, mature granulocytes, and T and B lymphocytes. The target antigen for WI-2 had a molecular weight of 43,000 daltons. Specimens from patients with leukemia were tested with WI-2. The number of immature cells was compared with the number of WI-2 reactive cells in the peripheral blood and bone marrow and subjected to linear regression analysis. There was a highly significant (p less than 0.001) correlation between the two parameters. The antibody may be useful in monitoring the progress of the patients and in detecting early relapse in leukemia.

Pleuropulmonary melioidosis in a Cambodian refugee

A 47-year-old Cambodian refugee presented with an acute respiratory illness that featured consolidation of the lower lobe of the left lung and progressive involvement of the adjacent pleura caused by Pseudomonas pseudomallei. Initial difficulty in identifying the organism resulted in an inadequate duration of therapy. Chronic pleural disease followed, and the organism became resistant to many antibiotics during therapy. A diagnosis of pleuropulmonary melioidosis should be entertained and the microbiology laboratory alerted when patients with pneumonia who are from endemic areas are encountered, so that a diagnosis can be made early and the appropriate treatment begun.

The primary structure of the COOH-terminal half of cholera toxin subunit A1 containing the ADP-ribosylation site

The sequence of 96 amino acid residues from the COOH-terminus of the active subunit of cholera toxin, A1, has been determined as (sequence; see text) This is the largest fragment obtained by BrCN cleavage of the subunit A1 (Mr 23,000), and has previously been indicated to contain the active site for the adenylate cyclase-stimulating activity. Unequivocal identification of the COOH-terminal structure was achieved by separation and analysis of the terminal peptide after the specific chemical cleavage at the only cysteine residue in A1 polypeptide. The site of self ADP-ribosylation in the A1 subunit [C. Y. Lai, Q.-C. Xia, and P.T. Salotra (1983) Biochem. Biophys. Res. Commun. 116, 341-348] has now been identified as Arg-50 of this peptide, 46 residues removed from the COOH-terminus. The cysteine that forms disulfide bridge to A2 subunit in the holotoxin is at position 91.

Characterization and localization of atriopeptin in rat atrium

An antiserum specific for atriopeptin was used to characterize and localize atriopeptin-like immunoreactive material in rat atrium by radioimmunoassay and immunohistochemical techniques. The antiserum recognizes atriopeptin I, atriopeptin III, and alpha-human atrial natriuretic polypeptide, but does not recognize met-enkephalin, cholecystokinin, dynorphin A, bradykinin, substance P, or beta-endorphin. A high content of atriopeptin was found in crude extracts of rat atria, as compared to ventricles, and the atriopeptin-like immunoreactive material was found to be located exclusively in granules within atrial cardiocytes. Fractionation of the immunoreactive material by gel filtration and reverse-phase HPLC revealed the presence of multiple atriopeptins.

Depressor and natriuretic activities of several atrial peptides

Mammalian atria contain peptides that have depressor and natriuretic activities. Four peptides, atriopeptin I to III (AP I to III) and alpha-human atrial natriuretic factor (alpha-hANP), were synthesized and assayed in the urethane-anesthetized rat for cardiovascular changes and natriuretic activities. All four peptides produced depressor responses and natriuresis. The relative activities were: alpha-hANP = AP III greater than AP II greater than AP I. The disappearance of iodinated AP III from plasma was rapid, with an estimated half-life of 2.5 min. Atriopeptin III was degraded by tissue homogenates, the relative activities being: kidney greater than liver greater than lung greater than plasma greater than heart. The HPLC profile of AP III suggested that smaller peptide fragments were formed after incubation with kidney homogenates. The degradation of AP III was inhibited by bestatin, an aminopeptidase inhibitor, and SQ 20881, a carboxypeptidase inhibitor.

Mouse monoclonal antibody (WI-MN-1) against malignant melanoma

A mouse monoclonal antibody, WI-MN-1, was raised against G-361 melanoma cell line. Reactivity of this antibody was characterized by indirect immunofluorescence against 22 cell lines and normal and neoplastic human tissues. Positive reactions were seen against three melanoma cell lines (G-361, HT-144, and MeWo). It also reacted against an epidermoid carcinoma cell line (Hep-2) and amnion cells (WISH). The antibody failed to react against cell lines derived from granulocytic leukemias, lymphocytic leukemias, Burkitt's lymphoma, carcinoma of the lung, carcinoma of the cervix, carcinoma of the colon, carcinoma of the breast, astrocytoma, and a human monocytoid cell line. Mouse melanoma and mouse fibroblast cell lines were also nonreactive. Similarly, there was no reaction against human peripheral blood, bone marrow, spleen, lymph node, thymus, breast, lung, stomach, heart, brain, kidney, liver, skin, or testis. The antibody was also tested by indirect immunofluorescence against 17 samples of metastatic malignant melanoma which were removed from 13 patients. WI-MN-1 gave positive reaction against 16 of these specimens, and it reacted with the cryostat section in the immunoperoxidase test, delineating neoplastic melanoma from the normal brain tissue. The antibody precipitated Mr 105,000 and 38,000 antigens from biosynthetically labeled G-361 cells. It was suggested that WI-MN-1 was a useful addition to the panel of monoclonal antibodies against melanoma-associated antigens.

Platelet associated IgG in uremia

Platelet-associated IgG (PAIgG) levels, a useful adjunct for the evaluation of patients with immunologic mediated thrombocytopenia, were obtained in 36 patients with end stage renal disease undergoing maintenance hemodialysis. Twenty-five of the 36 had elevated PAIgG. Nine of the 36 were thrombocytopenic and only 3 of the 9 had elevated PAIgG. Fifteen patients in the group admitted to recent substance abuse. All but one had elevated PAIgG and only one patient was thrombocytopenic. In contrast to patients with idiopathic immune thrombocytopenic purpura (ITP), a direct relationship was not found between PAIgG and total platelet protein (TPP) in the uremic group. It can be concluded that PAIgG values in patients with uremia are difficult to interpret since elevated PAIgG values are found in the majority of uremic patients with normal platelets counts.

Monoclonal antibody against myeloid leukemia cell line (KG-1)

A murine monoclonal antibody (WI-5) was produced against a myeloid leukemia cell line (KG-1). The antibody was immunoglobulin G3K. It reacted only against KG-1 cells and failed to react against 33 other cell lines representing fibroblasts, solid tumors, and cells of myeloid and lymphatic origin. It also showed no reaction against normal red blood cells, granulocytes, platelets, monocytes, and T- and B-lymphocytes. Similarly, there was no reaction against lymphocytes transformed by mitogens. Peripheral blood and bone marrow samples from acute granulocytic and acute lymphocytic leukemia, chronic granulocytic leukemia, chronic granulocytic leukemia in blastic crisis, and chronic lymphocytic leukemia failed to react with WI-5. It was suggested that WI-5 detected a unique antigen on KG-1 cells.

Immunoreactive dynorphin-(1-8) and corticotropin- releasing factor in subpopulation of hypothalamic neurons

Immunoreactive corticotropin-releasing factor (CRF) and dynorphin-(I-8) were visualized in rat hypothalamus by immunohistofluorescence with specific antibodies. In brains from colchicine-treated, adrenalectomized rats, neuronal perikarya with immunoreactive CRF were observed in the paraventricular nucleus of the hypothalamus. The CRF occurred together with the dynorphin-(1-8). However, the CRF immunoreactivity occurred only in a subpopulation of the dynorphin-(1-8) immunoreactive cells. These findings suggest that there may be a functional interrelationship of CRF with dynorphin-related opioid peptides and provide further evidence that neurons may contain more than one bioactive substance.

Investigations of the possible functions for glycosylation in the high mobility group proteins. Evidence for a role in nuclear matrix association

Techniques are described for selectively removing the carbohydrate moieties from the high mobility group (HMG) 14 and 17 proteins of Friend erythroleukemia and calf thymocyte cells without causing degradation of these nonhistone proteins. Investigations were therefore undertaken to investigate the possible significance of this secondary biochemical modification by comparing the activity of the HMGs with and without their glycosyl side chains in various functional assays of the proteins. For example, these HMGs have been found to be equally effective in the partial inhibition of the histone deacetylase enzymes of mammalian cell nuclei whether or not they contain covalently bound carbohydrate residues. We also investigated the possibility that the glycosyl modifications might be involved in the reported ability of these HMGs to specifically cause reconstitution of the DNase I-sensitive structure of "active" genes in salt-depleted chromatin. Unexpectedly, in experiments with both the active beta-globin gene of Friend cells and the total complement of active genes in these same mouse cells (which can be preferentially labeled by nuclear nick translation) we have been unable, using purified HMG 14 and 17 preparations, to reconstitute the active DNase I structure of genes in salt-depleted chromatin preparations. Therefore, the possible role, if any, played by HMG glycosylation in such reconstitution experiments remains unknown. However, in the course of these experiments we did find that HMG 14 and 17 proteins covalently linked to carbohydrate side chains bind preferentially to the nuclear protein matrix of mammalian cells. Furthermore, this association appears to be mediated through the glycosyl side chains since enzymatic removal of these modifications from the HMGs greatly reduced their binding to the nuclear matrix. Since numerous workers have implicated the nuclear matrix as the site of both RNA transcription and DNA replication in eukaryotic cells, the finding of HMG association with this nuclear structure may have significance for our understanding of the overall architectural organization of the active domains of chromatin in cells.

Monoclonal antibody against a unique antigen on human acute promyelocytic leukemia cell line (HL-60)

An IgM kappa monoclonal antibody (WI-1) reacted against HL-60 cells in indirect immunofluorescence and microcytotoxicity tests. It failed to react against 19 other cell lines representing acute myelogenous leukemia, chronic myelogenous leukemia, lymphocytic leukemias, multiple myeloma, Burkitt's lymphoma, monocytoid cells and virus induced lymphoid cell lines. Normal peripheral blood nucleated cells and bone marrow cells derived from acute granulocytic leukemia, chronic granulocytic leukemia, acute lymphocytic leukemia, and chronic lymphocytic leukemia also failed to react with WI-1. Normal peripheral blood lymphocytes, transferred with mitogens, showed no reaction against the antibody. There was some decrease in the reactivity of the cells, against WI-1, following maturation with dimethyl sulfoxide. However, a large percentage of the cells remained positive after maturation. WI-1 reacted specifically against an antigen on the HL-60 cells which had a molecular weight of about 42,000 dalton. Peripheral blood cells from one patient with acute promyelocytic leukemia failed to react with the antibody. It is possible that acute promyelocytic leukemia is an antigenically heterogeneous disease. A large population of acute promyelocytic leukemia patients needs to be tested to see if the specific antigen on HL-60 cells, detected by WI-1, is demonstrable in other patients with acute promyelocytic leukemia.

In vitro potentiation of the activity of synthetic ovine corticotropin-releasing factor by arginine vasopressin

The ability of arginine vasopressin (AVP) to potentiate the actions of synthetic ovine corticotropin-releasing factor (CRF) was examined using anterior pituitary fragments. Marked potentiation of ACTH release was observed upon incubating the fragments with a combination of 2 nM AVP and 1 nM CRF. Potentiation of CRF-induced ACTH release was also observed when the fragments were incubated with a combination of 1 nM AVP and 0.5 nM CRF. These results suggest that AVP may play a role in the release of ACTH from the adenohypophysis.

Immunocytochemical localization of CRF in the ovine hypothalamus

A population of neuronal cell bodies and their fiber pathways have been elucidated within the ovine hypothalamus. The immunoreactive neurons were located in the anterior and dorsal hypothalamus interspersed throughout the paraventricular nucleus. These perikarya were only observed when an antiserum that was generated against the C-terminal of CRF was employed. A dense fiber projection traversed the medial-basal hypothalamus and ended within the palisade-contact zone of the median eminence and neural stem. Fibers were revealed by antisera generated against both the N-terminal and the C-terminal of CRF. Antisera pre-absorbed with synthetic CRF failed to yield immunoreactivity.

Structure and organization of tRNA, rRNA, and protein genes in neurospora crassa mitochondria

Our studies on Neurospora crassa mitochondria have included sequence analysis of tRNAs, mapping and cloning of the tRNA, rRNA, and protein genes and the DNA sequence analysis of these genes. Results from tRNA sequence analyses explain how the mitochondrial protein synthesizing system can function with a much smaller number of tRNAs than other systems. Mapping studies have shown that the two rRNA genes and almost all of the tRNA genes are clustered onto a third of the mitochondrial genome. The two rRNA genes and all of the tRNA genes are coded for by the same DNA strand. DNA sequence analysis has provided several interesting results. Twenty-four tRNA genes have been identified. Highly conserved GC rich palindromic sequences flank tRNA genes. The intervening sequence within the large rRNA gene has a long open reading frame capable of coding for a protein 426 amino acids long. The gene for cytochrome oxidase subunit 3 has been localized within the tRNA-rRNA gene cluster and has been sequenced. This gene is also flanked by the highly conserved GC rich palindromic DNA sequences.

A synthetic peptide capable of eliciting antibodies that neutralize human chorionic gonadotropin

Antisera generated to the human chorionic gonadotropin beta-subunit (hCGbeta) have been shown not only to neutralize the biologic activity of hCG but also to cross-react with human luteinizing hormone (hLH). In an attempt to reduce such cross-reactivity, a peptide fragment analogous to the amino acid sequence of the carboxylterminal 45 residues (101-145) of the hCGbeta-subunit with alpha-aminobutyric acid substituting for cysteine at position 110 was synthesized and tested for ability to produce antibodies interacting with hCG. Antisera were generated in rabbits to a conjugate of this peptide with tetanus toxoid emulsified with Freund's complete adjuvant. Antibody titers and specificity were assessed by the double-antibody technique. The results show that the antisera to the synthetic hCGbeta fragment bound 125I-labeled hCG and did not cross-react with hLH in the radioimmunoassay system. Most importantly, the antisera effectively neutralized the biologic activity of hCG as determined by the rat uterine weight assay.

Carbohydrate modifications of the high mobility group proteins

This paper reports the results of numerous biochemical analyses which indicate that the "high mobility group" proteins (HMGs) of mouse and bovine cells are bona fide glycoproteins and can, in addition, be modified by poly(ADP-ribose) addition in vitro. The sugars N-acetylglucosamine, mannose, galactose, glucose, fucose, and one unknown sugar (possibly xylose) have been identified in purified preparations of HMGs 14 and 17. Furthermore, the fucose-specific lectin Ulex europeus agglutinin I bound both to the isolated HMGs and to monomer nucleosomes containing HMGs released from "active chromatin" by micrococcal nuclease digestion. Selective alkaline borohydride reductive cleavages of the HMGs suggested that the oligosaccharide prosthetic groups are primarily bound to these proteins by N-glycosidic linkages. The unexpected finding that the HMGs contain covalently bound complex carbohydrate moieties allows for a potentially great amount of variability and specificity in these proteins that may have important biological implications.

Human platelet-derived growth factor. Purification and resolution into two active protein fractions

Human platelets secrete a factor that stimulates cultured human cells to initiate DNA synthesis and to divide. This human platelet-derived growth factor (PDGF) has been purified congruent to 100,000-fold into two equally active homogeneous fractions, PDGF I (Mr congruent to 31,000) and PDGF II (Mr congruent to 28,000). The amino acid compositions of each are similar, highly basic, and show 18 half-cystine residues. Both PDGF I and II are glycoproteins, but differ in their carbohydrate compositions. The data suggest that PDGF II may be a proteolytic cleavage product of PDGF I but do not rule out that the proteins may be separate but very similar gene products. Purified PDGF is active in stimulating DNA synthesis at 0.2 ng/ml.

Platelet factor 4 is chemotactic for neutrophils and monocytes

Platelet factor 4 is shown to be a chemotactic protein for human polymorphonuclear leukocytes and monocytes at concentrations found in human serum and reached locally in injured tissue. The maximum chemotactic response to platelet factor 4 nearly equals that achieved with saturating concentrations of the chemotactic activity derived from the fifth component of human complement, C5. Cells desensitized to C5 chemotactic activity retain chemotactic responsiveness to platelet factor 4. Serum contains inhibitory capacity against the chemotactic activity associated with platelet factor 4. Our results suggest that the local release of platelet factor 4 may be an important stimulus attracting inflammatory cells to sites of blood vessel injury.

In vivo and in vitro release of ACTH by synthetic CRF

The 41-residue corticotropin releasing factor (CRF) was synthesized by the solid phase method. The synthetic CRF and arginine vasopressin (AVP) were examined for ACTH releasing activity and effects on the release of 5 other pituitary hormones in vivo and in vitro. Injection of the CRF into pharmacologically blocked rats increased plasma corticosterone levels in a dose-related manner. The minimum effective dose was 1.6 x 10(-12) mol/100 g body weight. CRF also significantly stimulated release of ACTH-like immunoreactivity in a dose-related manner from rat pituitary quarters beginning at a concentration of 10(-9) M. AVP, a peptide known to have CRF activity, exhibited slightly lower corticotropin releasing activity than the CRF at equimolar dose levels. Secretion of other pituitary hormones was not appreciably altered by either the CRF or AVP.

Design, synthesis, and biological activity of peptides which release growth hormone in vitro

Experimental observations showed that the analogs [D-Trp2]- and [D-Phe2]methionine enkephalin amide were weakly active in releasing GH from rat pituitary in vitro. These observations were used to design more active GH-releasing factors. Conformational energy calculations were carried out, and energetically favored conformations of these polypeptides were found. Structural similarities as well as structural differences between active and inactive analogs were examined, and new sequences were predicted. Progressively more active analogs were designed, then synthesized, and tested. This cycle of steps was repeated, each time using structural and chemical concepts as design guides, until a series of very active analogs resulted. The most active analog to date, Tyr-D-Trp-Ala-Trp-D-Phe-NH2, was shown to release GH in vitro at 10-30 ng/ml medium, which is approximately 10(3) times more active than the two starting enkephalin-based analogs. From the structure-activity data, a mechanism for binding at the receptors is formulated, and a comparison is made between the structural relationships of the GH-releasing peptide analogs and the GH inhibitor, somatostatin.