Dynorphin is a specific endogenous ligand of the kappa opioid receptor

In the guinea pig ileum myenteric plexus--longitudinal muscle preparation, dynorphin-(1--13) and the prototypical kappa agonist ethylketocyclazocine had equally poor sensitivity to naloxone antagonism and showed selective cross protection in receptor inactivation experiments with the alkylating antagonist beta-chlornaltrexamine. In binding assays with membranes from guinea pig brain, ethylketocyclazocine and dynorphin-(1--13) amide were more potent in displacing tritium-labeled ethylketocyclazocine than in displacing typical mu and delta opioid receptor ligands. In the two preparations studied, the dynorphin receptor appears to be the same as the kappa opioid receptor.

Dynorphin-(1-13), an extraordinarily potent opioid peptide

We describe the opioid properties of a tridecapeptide, the sequence of which corresponds to the NH2-terminal sequence of dynorphin, a novel porcine pituitary endorphin. It contains [Leu]enkephalin. In the guinea pig ileum longitudinal muscle preparation it is about 700 times more potent than [Leu]enkephalin. Its effects in this tissue are blocked completely by naloxone, but the apparent affinity of naloxone is 1/13th that for blockade of [Leu]enkephalin or normorphine. In the mouse vas deferens, this peptide is 3 times more potent than [Leu]enkephalin. Well-washed rat brain membranes degrade the peptide rapidly, suggesting the presence of a membrane-bound degradative enzyme. The peptide displays considerable immunoreactivity in assays with antisera that have been used for the immunohistochemical localization of [Leu]enkephalin. The remarkable enhancement of the potency of [Leu]enkephalin by the COOH-terminal extension -Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys-OH suggests new interpretations concerning the structure of opiate receptors and the function of the enkephalin pentapeptides.

Dynorphin and vasopressin: common localization in magnocellular neurons

The opioid peptide dynorphin is widely distributed in neuronal tissue of rats. By immunocytochemical methods, it was shown previously that dynorphin-like immunoreactivity is present in the posterior pituitary and the cells of the hypothalamic neurosecretory magnocellular nuclei which also are responsible for the synthesis of oxytocin, vasopressin, and their neurophysins. By using an affinity-purified antiserum to the non-enkephalin part of the dynorphin molecule it has now been demonstrated that dynorphin and vasopressin occur in the same hypothalamic cells of rats, whereas dynorphin and oxytocin occur in separate cells. Homozygous Brattleboro rats (deficient in vasopressin) have magnocellular neurons that contain dynorphin separate from oxytocin. Thus dynorphin and vasopressin, although they occur in the same cells, appear to be under separate genetic control and presumably arise from different precursors.

Stereospecific nicotine receptors on rat brain membranes

A stereospecific binding site for nicotine has been detected on rat brain membranes. Competition studies with cholinergic agonists suggest that this site is a nicotinic cholinergic receptor.

Diabetes mellitus, other medical conditions and familial history of cancer as risk factors for pancreatic cancer

In a population-based case-control study of pancreatic cancer conducted in three areas of the USA, 484 cases and 2099 controls were interviewed to evaluate the aetiologic role of several medical conditions/interventions, including diabetes mellitus, cholecystectomy, ulcer/gastrectomy and allergic states. We also evaluated risk associated with family history of cancer. Our findings support previous studies indicating that diabetes is a risk factor for pancreatic cancer, as well as a possible complication of the tumour. A significant positive trend in risk with increasing years prior to diagnosis of pancreatic cancer was apparent (P-value for test of trend = 0.016), with diabetics diagnosed at least 10 years prior to diagnosis having a significant 50% increased risk. Those treated with insulin had risks similar to those not treated with insulin (odds ratio (OR) = 1.6 and 1.5 respectively), and no trend in risk was associated with increasing duration of insulin treatment. Cholecystectomy also appeared to be a risk factor, as well as a consequence of the malignancy. Subjects with a cholecystectomy at least 20 years prior to the diagnosis of pancreatic cancer experienced a 70% increased risk, which was marginally significant. In contrast, subjects with a history of duodenal or gastric ulcer had little or no elevated risk (OR = 1.2; confidence interval = 0.9-1.6). Those treated by gastrectomy had the same risk as those not receiving surgery, providing little support for the hypothesis that gastrectomy is a risk factor for pancreatic cancer. A significant 40% reduced risk was associated with hay fever, a non-significant 50% decreased risk with allergies to animals, and a non-significant 40% reduced risk with allergies to dust/moulds. These associations, however, may be due to chance since no risk reductions were apparent for asthma or several other types of allergies. In addition, we observed significantly increased risks for subjects reporting a first-degree relative with cancers of the pancreas (OR = 3.2), colon (OR = 1.7) or ovary (OR = 5.3) and non-significantly increased risks for cancers of the endometrium (OR = 1.5) or breast (OR = 1.3). The pattern is consistent with the familial predisposition reported for pancreatic cancer and with the array of tumours associated with hereditary non-polyposis colon cancer.

Cloning and pharmacological characterization of a rat kappa opioid receptor

A full-length cDNA was isolated from a rat striatal library by using low-stringency screening with two PCR fragments, one spanning transmembrane domains 3-6 of the mouse delta opioid receptor and the other unidentified but homologous to the mouse delta receptor from rat brain. The novel cDNA had a long open reading frame encoding a protein of 380 residues with 59% identity to the mouse delta receptor and topography consistent with a seven-helix guanine nucleotide-binding protein-coupled receptor. COS-1 cells transfected with the coding region of this clone showed high-affinity binding to kappa opioid receptor-selective ligands such as dynorphin A and U-50,488 and also nonselective opioid ligands such as bremazocine, ethylketocyclazocine, and naloxone. Not bound at all (or bound with low affinity) were dynorphin A-(2-13), enantiomers of naloxone and levophanol [i.e., (+)-naloxone and dextrorphan], and selective mu and delta opioid receptor ligands. Activation of the expressed receptor by kappa receptor agonists led to inhibition of cAMP. Finally, in situ hybridization revealed a mRNA distribution in rat brain that corresponded well to the distribution of binding sites labeled with kappa-selective ligands. These observations indicate that we have cloned a cDNA encoding a rat kappa receptor of the kappa 1 subtype.

Specific receptor for the opioid peptide dynorphin: structure--activity relationships

The structural features responsible for the high potency and opiate receptor specificity of the opioid peptide dynorphin in the guinea pig ileum myenteric plexus were examined. Successive removal of COOH-terminal amino acids from dynorphin-(1--13) demonstrated important contributions of lysine-13, lysine-11, and arginine-7 to the potency. Removal of the NH2-terminal tyrosine abolished the biologic activity. Several other structural modifications were shown to affect potency: substitution of D-alanine for glycine-2 reduced the potencies of dynorphin-(1--13) amide, -(1--11), and -(1--10); and methyl esterification of the COOH terminus enhanced the potencies of dynorphin-(1--12), -(1--10), -(1--9), -(1--8), and -(1--7). Within the dynorphin sequence, lysine-11 and arginine-7 were found to be important for selectivity of interaction with the dynorphin receptor, which is distinguishable from the mu receptor in this tissue.

Sequence and expression of the rat prodynorphin gene

We report here the isolation of a lambda genomic clone that contains the nucleotide sequence coding for the main exon of the rat prodynorphin (proenkephalin B) gene. This exon codes for the majority of the translated region of prodynorphin mRNA including the opioid peptides alpha-neo-endorphin, dynorphin A, and dynorphin B. The entire 3' untranslated region is also contained on the lambda clone. Nucleotide sequence comparison with the main exon of the human prodynorphin gene reveals both structural and sequence homology. RNA blot analysis reveals that prodynorphin transcripts can be seen in numerous regions of the rat brain and in the adrenal gland, spinal cord, testis, and anterior pituitary.

Dynorphin immunocytochemistry in the rat central nervous system

The distribution of dynorphin in the central nervous system was investigated in rats pretreated with relatively high doses (300-400 micrograms) of colchicine administered intracerebroventricularly. To circumvent the problems of antibody cross-reactivity, antisera were generated against different portions as well as the full dynorphin molecule (i.e., residues 1-13, 7-17, or 1-17). For comparison, antisera to [Leu]enkephalin (residues 1-5) were also utilized. Dynorphin was found to be widely distributed throughout the neuraxis. Immunoreactive neuronal perikarya exist in hypothalamic magnocellular nuclei, periaqueductal gray, scattered reticular formation sites, and other brain stem nuclei, as well as in spinal cord. Additionally, dynorphin-positive fibers or terminals occur in the cerebral cortex, olfactory bulb, nucleus accumbens, caudate-putamen, globus pallidus, hypothalamus, substantia nigra, periaqueductal gray, many brain stem sites, and the spinal cord. In many areas studied, dynorphin and enkephalin appeared to form parallel but probably separate anatomical systems. The results suggest that dynorphin occurs in neuronal systems that are immunocytochemically distinct from those containing other opioid peptides.

Comparison of the distribution of dynorphin systems and enkephalin systems in brain

A study of the anatomical distribution of the endogenous opioid dynorphin in rat brain showed that the peptide is localized in a widespread system with multiple cell groups and projections. This network is revealed by the use of multiple antiserums against dynorphin and can be distinguished from the system containing methionine-enkephalin and leucine-enkephalin, which is mapped by the use of antiserums against the enkephalins and biosynthetically related peptides in the adrenal. It thus appears that the brain contains at least three separate opioid neuronal networks: an enkephalin family with components similar to those found in the adrenal, a beta-endorphin family, and a dynorphin family.

Forced expiratory flows and volumes in infants. Normative data and lung growth

Forced expiratory flows (FEF) can be measured in infants from lung volumes initiated near total lung capacity. In order to establish reference values and to evaluate lung growth, we obtained measurements in 155 healthy subjects between 3 and 149 wk of age. Forced vital capacity (FVC) was highly correlated with body length; however, after accounting for length, age was also significant. When subjects were divided at the median age (40 wk) younger compared with older subjects had a significantly larger slope for length (3.7 versus 2.8; p = 0.002). The flow parameters (FEF(50), FEF(75), FEF(85), and FEF(25-75)) were highly correlated with length, and those infants whose mothers smoked had lower flows. For FEF(75), male subjects had lower flows than female subjects. The relationship between FEF and volume was assessed using FEV(0.5)/FVC, which decreased with increasing length. Smaller subjects emptied their lung volume proportionately faster. We conclude that our study provides reference values for this age group and demonstrates that smoke-exposed infants and male subjects have decreased FEF. In addition, our findings indicate that lung volume increases most rapidly during the first year of life and that airways are large relative to lung volume very early in life.

ZONE BEHAVIOR OF ENZYMES : ILLUSTRATED BY THE EFFECT OF DISSOCIATION CONSTANT AND DILUTION ON THE SYSTEM CHOLINESTERASE-PHYSOSTIGMINE

1. The kinetics of the reversible combination of one enzyme center with one molecule of a substrate or inhibitor is treated as a true bimolecular instead of a pseudomonomolecular reaction. The general equations describing such a reaction are presented and analyzed algebraically and graphically. 2. A new term, "specific concentration," is introduced to denote the concentration of reactants in units equal to the dissociation constant. Its use makes the kinetic equations universally applicable to all reversible systems of the given type. 3. It is shown that such a system exhibits three "zones" of behavior. Each zone is characterized and shown to exhibit significant differences in the function relating the concentrations of the components of the system at equilibrium. The zone boundaries are rigorously defined in terms of the specific enzyme concentration, for the mathematical error tolerable with a given experimental accuracy; and approximate boundaries for practical use are proposed. 4. The classical treatment of enzyme kinetics is shown to be a limiting case valid only for low specific enzyme concentrations (zone A) and to be inapplicable in a number of systems whose dissociation constants are very small or whose molar enzyme concentrations are very great, and in which, therefore, the specific enzyme concentrations are large. See Table I for a summary of zone differences. 5. In an enzyme system containing substrate or inhibitor, dilution before determination of reaction velocities is shown to be a crucial operation, entailing large changes in the fraction of enzyme in the form of a complex. The changes in fractional activity or inhibition with dilution are shown to be a function of specific enzyme concentration, the dilution factor, and the fraction of enzyme initially in the form of complex. Equations are given permitting the calculation of the state of the system at any concentration. The errors introduced into physiological work by failure to take the dilution effect into account are pointed out. 6. Experimental data are presented showing that the system composed of serum cholinesterase and physostigmine behaves as predicted by the dilution effect equations. 7. Two other conclusions of practical pharmacological importance are drawn from the theory of zone behavior: (a) The finding that a biological response is a linear function of the dose of a drug does not necessarily mean that the reaction is irreversible, but only that if reversible, the reactant with which the drug combines has a high specific concentration. (b) If a tissue enzyme has a high specific concentration, all reversible inhibitors will be equally potent in combining with it, regardless of their relative potency in dilute systems; provided only that their dissociation constants are within certain broad limits. 8. It is shown how the type of analysis here applied to bimolecular reactions can be applied in toto to systems of the type E + nX ⇋ EX_n, where n molecules of substrate or inhibitor unite with one enzyme center. The zone boundaries and the magnitude of the dilution effect change with n, but the general characteristics of the zones are the same for all values of n. 9. Since the analysis is based only on mass law assumptions, it is applicable to any system that is formally analogous to the one here treated.

Opioid activity of a peptide, beta-lipotropin-(61-91), derived from beta-lipotropin

The pituitary peptide beta-lipotropin displays essentially no opoid activity in a preparation of guinea pig ileum or in the opiate receptor binding assay. However, a fragment, beta-lipotropin-(61-91), with the enkephalin sequence (Tyr-Gly-Gly-Phe-Met) at its NH2-terminus, has typical opioid effects in these two assays.

Porcine pituitary dynorphin: complete amino acid sequence of the biologically active heptadecapeptide

The full primary structure of the very potent opioid peptide dynorphin, from porcine pituitary, has been determined. It is (H)Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys-Trp-Asp-Asn-Gln(OH). The synthetic peptide with this sequence behaves identically to natural dynorphin in a number of ways, and it has the same potency in the guinea pig ileum myenteric plexus--longitudinal muscle bioassay. The potency is accounted for by the first 13 residues.

Early open reduction and internal fixation of the disrupted pelvic ring

Early open reduction and internal fixation (ORIF) of extremity fractures in patients with multiple injuries has been demonstrated to be safe, improve survival, and decrease the incidence of respiratory failure. Complications leading to abandonment of planned operative fixation and death in several patients with pelvic fractures led us to initiate a policy of early ORIF of the disrupted pelvic ring. Early ORIF of the pelvis was performed in 15 multiply injured patients between May 1984 and August 1985. Patients ranged in age from 13 to 79 years, their Hospital Trauma Index-ISS scores ranged from 14 to 68, and number of preoperative transfusions ranged from 0 to 42. Types of fractures were A-P compression, two, lateral compression, one, vertical shear, seven, complex, two, and acetabulum with ring disruption, three. All patients were resuscitated, transported in pneumatic antishock garments, and evaluated by abdominal and pelvic CT scan (in two patients following celiotomy). Preoperative angiograms to assess retroperitoneal hemorrhage in eight patients resulted in identification and control of significant bleeding in five. The mean time from injury to pelvic stabilization was 38 hours. Seven patients underwent ORIF within the first 24 hours. In most cases simultaneous anterior and posterior internal fixation was performed with the patient in the lateral decubitus position. Excluding associated procedures, operative time averaged 5.1 hours. Intra-operative transfusions averaged 4 units (range, 0-11). Rigid fixation was achieved in all patients. Most patients were out of bed by the third postoperative day. No patient developed respiratory failure. Two patients developed wound infections. Modification of our technique has avoided this complication in the latter part of this series.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereospecific and nonspecific interactions of the morphine congener levorphanol in subcellular fractions of mouse brain

A METHOD IS DESCRIBED FOR ANALYZING THE ASSOCIATION OF THE OPIATE NARCOTIC LEVORPHANOL WITH BRAIN TISSUE INTO THREE COMPONENTS: nonsaturable, saturable nonspecific, and saturable stereospecific. The method may be of general applicability for the study of the interaction of drugs with body tissues. In mouse brain the stereospecific binding of levorphanol represents only 2% of the total association of drug with tissue, and it was found only in certain membrane fractions. The material responsible for the stereospecific binding might be the opiate receptor.

Endorphins: naloxone fails to alter experimental pain or mood in humans

In 30 human subjects, experimental pain was produced by either ischemia or cold-water immersion. In a double-blind procedure, intravenous doses of up to 10 milligrams of naloxone hydrochloride in saline were indistinguishable from similarly administered saline alone. There were no effects on subjective pain ratings, finger plethysmograph recordings, or responses to mood-state questionnaires. These laboratory procedures do not activate any functionally significant pain-attenuating or mood-altering effect of endorphins.