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PubMed1982

[ACTH, beta-endorphin, lipotropins, and other pro-opiocortin-derived peptides: a new family of hormones (author's transl)].

beta-Endorphin, a pituitary morphino-mimetic peptide, was identified in a culture medium derived from a human corticotropic adenoma. Secretion products from cultured human cells derived from a small-cell carcinoma of the lung were shown to contain a high molecular weight precursor analagous to pro-opiocortin: this molecule is a polypeptide of the order of 28,000 daltons the enzymatic processing of which leads to the coordinated and simultaneous release of different peptide fragments: ACTH, beta- and gamma-lipotropins, beta-endorphin, fragment 16 K and gamma 3-MSH. All these peptides have been identified in human plasma, and pituitary and non-pituitary tumor extracts. Their plasma concentrations vary in a parallel manner, beta-endorphin and a peptide very similar to beta-MSH have been detected in human hypothalamus.

Adenoma↗
PubMed1982

[Ontogenesis of pro-opio-melano-cortin neurons in the rat].

Immunocytochemical study of the pro-opio-melano-cortin neurones in rat fetuses and newborns indicates that: 1) they appear precociously in the mediobasal hypothalamus, as early as day 13 of fetal development, that is to say 3 days before pro-opio-melano-cortin-containing pituitary cells; 2) between day 13 and day 17 they display synchronous changes in their intracellular patterns of immunoreactivity, arguing in favour of their cyclic secreting activity, which precedes the establishing of their projections; 3) beginning with day 18 until birth, the somatal immunoreactivity disappears transitorily; during the same period and the first postnatal days, their immunoreactive fibres extend in various brain regions.

Adrenocorticotropic Hormone↗
PubMed1982

Structural organization of the corticotropin-beta-lipotropin precursor gene.

The human and the bovine corticotropin (ACTH)-beta-lipotropin (LPH) precursor gene have been isolated and characterized. Both genes consist of three exons which are divided by two large introns at exactly the same positions. One of the introns is inserted within the segment transcribed into the 5'-untranslated region of the mRNA, and the other interrupts the protein-coding sequence near the signal peptide region. The largest exon encodes most of the protein sequence which includes the three repeated melanotropin (MSH) peptides and other biologically active peptides such as ACTH and beta-endorphin. Thus, there is no apparent correspondence between the repetitive structure of the precursor protein and the structural organization of its gene. Comparison of the nucleotide sequences of the human and the bovine gene reveals that three regions are highly conserved, i.e., the region extending from the signal peptide to gamma-MSH, the ACTH region and the beta-MSH/beta-endorphin region. This suggests that the peptide(s) in the amino-terminal region, including gamma-MSH, may be of physiological importance, as is the case for ACTH and beta-endorphin. The different biologically active component peptides of the ACTH-beta-LPH precursor, encoded by a single gene, seem to be involved in the defense mechanism of the living organism by acting coordinately in the central nervous system as well as in peripheral tissues. The identification of the mRNA encoding the ACTH-beta-LPH precursor in a human ectopic ACTH-producing tumor is also reported.

Adrenocorticotropic Hormone↗
PubMed1983

A DNA polymorphism in close physical linkage with the proopiomelanocortin gene.

Cellular DNAs from a panel of 20 unrelated individuals were screened for restriction fragment length polymorphisms (RFLP) with a DNA probe containing the first exon of the proopiomelanocortin gene (POMC), which has been assigned to chromosome 2p23-25. Digestion with the restriction endonuclease Sst 1 revealed a high frequency RFLP. The two alleles that were found are fragments of 10- and 15-kilobase (kb) length and are in Hardy-Weinberg equilibrium with frequencies of 72.6% and 27.4%, respectively. Informative families were tested for linkage between POMC/Sst 1 RFLP and other polymorphic markers of chromosome 2. Linkage was excluded to AcP-1 (2p23-25) at 15% recombination, which is still consistent with the chromosomal assignments for these genes. The close physical linkage (10 kb) of the polymorphic locus to the POMC gene makes this RFLP a suitable marker for future linkage studies involving the POMC gene.

Chromosome Mapping↗
PubMed1984

Endorphins and psychiatry: pre-clinical perspectives.

The chemical relationships among the 3 major families of endorphins are summarized, and the CNS distribution and possible circuit functions are discussed. The overlapping distributions of enkephalin and dynorphin pathways is intriguing, and their existence in classical hippocampal pathways has implications for limbic function which are not understood. Functionally the predominant effect of these systems is 'disenabling', in contrast with the 'enabling' effects of monoamines, although specific and reversible excitatory responses in hippocampal pyramidal neurons may have important behavioral implications. The complex theoretical and methodological issues that arise in attempting to establish transmitter correlates of psychiatric disorders defy simplistic hypotheses. Endorphin research, where well established agonists and antagonists are available, illustrates the problems facing other areas of peptide research in conceptualizing a peptide related pathophysiology of the major psychoses. The structural, functional and chemical indices of hypothetical forms of endorphin pathology, and the reliability of various radio-immunoassays used now to quantify known endorphins are discussed. The complex range of behaviors produced in animals by endorphin antagonists continue to make research in this area important to psychiatry.

Animals↗
PubMed1983

Methods for evaluating response to treatment in adult acute leukemia.

The criteria for evaluating response to treatment for patients with adult acute leukemia are objective, quantitative, and effective. The first objective of treatment is to achieve a complete clinical and hematological remission, since in the absence of such response the disease has a rapidly progressive and inevitably fatal outcome. Logistic regression analysis and the generation of models for predicting the probability of response for each patient have proven to be extremely useful techniques for evaluating new candidates for front-line treatment in acute leukemia. In prospective tests, such modeling procedures have proven to predict accurately for response. It is evident that this methodology will be highly effective for selecting treatment for individual patients and for detecting improved treatments for patients who respond poorly to conventional treatment. For patients who achieve complete remission, the duration of that remission can also be evaluated by logistic regression analysis. Variables which predict for duration of remission have proven to be different from those variables which predict for probability of response. In addition, variables which predict for prolonged remission--that is, beyond 2 and 3 years--have proven to be different from variables which predict for relapse in the first year of remission. Therefore, the models which estimate risk of relapse per unit of time at risk should prove most valuable for evaluating not only the choice of treatments to be used during remission, but the duration of treatment and the strategy of treatment, that is, whether intensive treatment or low-dose intermittent treatment should be chosen. Finally, the demonstration that a significant fraction of the patients in complete remission will have long term disease-free and treatment-free survival makes the identification of such patients even more important. Evaluation of innovative higher-risk strategies for treatment of the patient in remission should be offered primarily to patients who have a low probability of having already been cured with conventional treatment. Thus, the rapid evolution of effective treatment for adult acute leukemia over the last 15 years has necessitated the development of more precise and more effective methods for evaluating the effects of those treatments on patients with this disease.

Acute Disease↗
PubMed1983

[Computer bank of amino acid sequences of protein hormones. Comparative analysis of the sequences in pro-opio-melanocortin, proenkephalin and prodynorphin: detection of phorphin--the 4th repeating peptide in prodynorphin].

Using a BESM-6 computer, a computer system for accumulation and comparative analysis of amino acid sequences (AS) of protein-peptide hormones and their precursors (the so-called computer bank of protein hormone AS) was developed. A Fortran-based program designed for construction of correspondence schemes of AS and their local similarity profiles was elaborated. In combination with the previous programs this system allows a rapid inclusion of the newly deciphered sequences into the corresponding homologous groups, thus complementing the correspondence scheme and specifying the evolution profiles. A comparative analysis of AS in proopiomelanocortin (POMC), proenkephalin (PENK) and prodynorphin (PDIN) revealed evolutionary-conservative and variable sites. The conservative sites of AS are active centers of the hormones. The leu-enkephalin analog, phorphin, the fourth repeating peptide of this precursor, was detected in prodynorphin, which, similar to beta-neo-endorphin, dynorphin and rimorphin may possess a biological activity. The similarity of the effector sites of the melanotropin sequence from POMC to the met-enkephalin sequence from PENK and leu-enkephalin sequence from PDIN as well as to gastrin and cholecystokinin was established. This may suggest that the hormone-receptor complexes in target organs of these hormones are also similar.

Amino Acid Sequence↗
PubMed1993

Natriuretic properties of melanocyte-stimulating hormones.

Proopiomelanocortin (POMC) is a protein that contains the amino acid sequences of numerous peptide hormones, including the melanocyte-stimulating hormones (MSH). MSH peptides of alpha, beta, and gamma primary structure are present in plasma, and all exhibit natriuretic activity. Intravenous infusion of alpha or beta-MSH leads to a time- and dose-dependent natriuresis, whereas gamma-MSH is reported to be natriuretic at low doses but antinatriuretic at high doses. The natriuretic activity of MSH peptides occurs without change in arterial pressure or renal hemodynamics, suggesting a possible direct tubular inhibition of sodium reabsorption. Intravenously infused gamma-MSH is associated with an increase in the plasma concentration of atrial natriuretic peptide. In addition, gamma-MSH also has a direct intrarenal natriuretic action that is dependent on the renal nerves. In rats, gamma-MSH-related peptides are involved in the reflex control of sodium excretion in situations such as the natriuresis that occurs (a) from the remaining kidney after acute unilateral nephrectomy, (b) from the contralateral kidney shortly after unilateral ureteral pressure elevation, and (c) after unilateral carotid artery traction. POMC-derived peptides (including MSH) are modulated in response to salt loading, and alterations in POMC metabolism and plasma peptide concentrations have been observed in genetically hypertensive rats and during the development of adrenal regeneration hypertension. In addition, plasma gamma-MSH levels are elevated in patients with severe congestive heart failure, and in primary hyperaldosteronism. These observations suggest a possible involvement of MSH-related peptides in sodium homeostasis as well as in certain forms of hypertension.

Animals↗
PubMed1993

A novel endogenous sodium-pump inhibitor in pig urine: purification and comparison with the inhibitor purified from bovine adrenal glands.

To clarify the chemical nature and pathophysiological significance of an endogenous, specific Na-pump inhibitor, extracts of various tissues have been examined. The activities were extracted by an Amberlite XAD-2 adsorbent and fractionated by high-performance liquid chromatography (HPLC) on an ODS column. Among many tissues and fractions tested, the extract of pig urine has been found to contain a large amount of 86Rb uptake inhibitory activities. The strongest inhibitory activity for 86Rb influx into erythrocytes also exhibited a cross-reactivity with anti-ouabain antibodies. This activity has been purified to homogeneity using five steps of reverse-phase HPLC. Although most of the dose-response curves for this purified Na-pump inhibitor, designated as uroxin, in the various assay systems paralleled those of ouabain and the inhibitor purified from bovine adrenal glands (designated as adrexin C), the cross-reactivity curve with anti-ouabain antibodies did not. The retention time of uroxin on an ODS HPLC column was also different from that of digoxin, ouabain, or adrexin C. 1H nuclear magnetic resonance spectroscopic study suggests that uroxin is a novel Na-pump inhibitor that is structurally different from any of the known cardiotonic steroids or the substances previously reported to exhibit Na-pump inhibitory activity. Thus, uroxin may be a new type of endogenous regulator for the Na pump.

Adrenal Glands↗
PubMed1995

Effects of voluntary ethanol ingestion on the POMC gene expression in the rat pituitary and on the plasma beta-endorphin content.

Studies investigating the influence of chronic ethanol treatment on the beta-endorphin content and the proopiomelanocortin (POMC) gene expression in the rat pituitary revealed contradictory results. Because of this we decided to start a more complex study to investigate the effects of isolation stress, chronic ethanol treatment and voluntary ethanol consumption on the POMC mRNA level in the rat pituitary. The immediately prepared total RNA from rat pituitaries was used in hybridization experiments (Northern- and Dot-blots). The results suggest a correlation between the POMC gene expression and the different fashions of 'living conditions' tested. So the POMC gene expression in long-term alcohol-treated animals was decreased supporting the theory of beta-endorphin deficiency in alcoholism. More interestingly, data obtained from the group of voluntary ethanol consumption suggest an inverse correlation between total ethanol ingestion and POMC gene expression. This indicates the importance of the method of ethanol administration. Consistent with a decreased POMC gene expression in the pituitary during chronic ethanol treatment are previous studies showing a decrease in the plasma beta-endorphin content in such situations. Surprisingly, in the present study the plasma beta-endorphin levels measured by radioimmunoassay were only slightly decreased in chronically ethanol-treated rats. This may be due to dysregulatory effects of ethanol on post-translational processing, degradation and/or release of beta-endorphin.

Alcohol Drinking↗
PubMed1994

Opioid peptides in the pituitary: a hormone, a paracrine modulator and a peptide in search of a function.

Endogenous opioid peptides derived from all three opioid precursors have been isolated from the pituitary of mammalian species. While beta-endorphin of the anterior lobe was soon shown to be secreted into the circulation as a hormone, the dynorphins and the enkephalins were found to occur in relative small quantities too low for export and effects in the periphery. With respect to the prodynorphin family in the neural lobe convincing evidence has been accumulated for a role of dynorphin A(1-8) in the local control of the release of the hormone oxytocin. The function of the enkephalins in the anterior and neural lobes, in spite of many efforts with in situ hybridization, immunocytochemistry, receptor autoradiography and receptor binding and bioassays, is still elusive. Research should be directed into the role of enkephalins in different physiological states, developmental stages and in non-mammalian vertebrate species.

Animals↗
PubMed1994

[The clinical significance serum N-POMC level in lung cancer patients].

Serum N-POMC level of 103 cases of lung cancer were measured in our hospital. The results were as follows: The lung cancer group, 50.5%, of patienst has an N-PONC level above the normal upper limit. The percentages of the N-POMC levels above the normal limit in lung cancers, such as: squamous-cell carcinoma, adenocarcinoma, SCLC and undifferentiated carcinoma were 52.2%, 50.0%, 47.3% and 57.1%, respectively. There was no statistically significant difference of N-POMC levels among these kinds of lung cancers, Eleven of 18 cases of SCLC patients in stage IIIb or IV, and 3 of 9 cases of SCLC patients in stage IIIa had N-POMC levels above the upper normal limit. Could serum N-POMC be one of the indexes for assisting the diagnosis and prognosis of lung cancer needs further investigation. Cases with carcinoid, thymoma and neurofibroma had higher N-POMC levels too. Six patients had Cushing syndrome.

Adenocarcinoma↗