Conversion of leumorphin (dynorphin B-29) to dynorphin B and dynorphin B-14 by thiol protease activity

Dynorphin B (rimorphin) is formed from leumorphin (dynorphin B-29) by the action of a thiol protease from rat brain membranes, in a single step. This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. We have observed that in addition to dynorphin B, dynorphin B-14 is formed from dynorphin B-29. Among the various protease inhibitors tested, none except p-chloromercuribenzensulfonic acid inhibited the formation of the two products. Both temperature and pH had similar effects on the formation of dynorphin B-14 and dynorphin B. The inhibitory potencies of adrenocorticotropic hormone, peptide E, and dynorphin A were virtually identical for the formation of the two products. These results suggest that the same enzyme may be responsible for the formation of dynorphin B-14 and dynorphin B.

Use of the contrast-enhanced CT enema in the management of penetrating trauma to the flank and back

There have been few innovations in the management of penetrating trauma of the flank and back since that reported by Peck and Berne in 1981. During 1984-1985 our Trauma Service treated 119 patients with injuries in these areas. In 56 patients management was based on the results of the contrast-enhanced CT enema (CECTE), a computerized tomographic technique designed to delineate all of the retroperitoneal viscera by simultaneously opacifying the small bowel, duodenum, colon, GU tract, and major vessels. Specific radiographic findings were present on 44 scans. Twelve scans were negative. Six scans were considered indications for angiography because of the proximity of the identified missile wounds or their hematomas to major vascular structures. One of these arteriograms revealed a renal artery pseudoaneurysm which would otherwise have remained undiagnosed. In 30 cases the penetrating wounds were well delineated by CECTE, and their nature and location were considered appropriate for nonoperative management. None required subsequent exploration. In eight cases CECTE demonstrated that the wounds were located so as to place specific viscera at risk for significant injury, but no definite injury was identified. Five of these patients were successfully managed by further evaluation and close observation, two were explored, and one signed out of the hospital. No scan demonstrated extravasation from a hollow viscus. Overall, 52 of our 56 patients (92%) were successfully managed nonoperatively on the basis of the interpretation of their CECTE findings. CECTE can be useful in the management of stable patients with penetrating trauma to the back and flank by identifying the nature and location of the resulting retroperitoneal injuries.(ABSTRACT TRUNCATED AT 250 WORDS)

The challenge of an aging population. The case of the People's Republic of China

Policymakers and demographers in China are cognizant of the implications of the one-child family policy for the eventual aging of their nation's population and are beginning to incorporate attention to the elderly into the economic and population policies being developed. A major stumbling block to the acceptance of the one-child family policy, especially in rural areas, has been fear about security in old age. As the one-child family becomes widely established, it will become increasingly difficult for the only child to support two elderly parents.

Comparative immuno-removal: a novel method for estimating the concentration of an unknown immunoreactive compound

We describe a method for estimating the molar concentration of an unknown immunoreactive compound. The amount of antibody required to bind half of a standard is compared to the amount required to bind half of an equal number of immunoreactive equivalents of the unknown. We demonstrate the utility of the method using a morphine antibody affinity resin and compounds structurally related to morphine.

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)

Brain chemistry and the addictions

This is a very exciting period for basic discoveries in the field of neuroscience. We can begin to hope for the kinds of understanding that will give us medical insight into the causes and mechanisms of the addictions. Such knowledge may open the way for methods of prevention and treatment by means we can hardly imagine today. Tests for genetic vulnerability to addiction, so that prevention measures can be focused on those who would benefit most? Stimulation of the production of endogenous brain chemicals? Repair of genetic defects in peptide or receptor production? Immunizations? Long-term replacement therapies? Who knows? The next decade or two should see exciting developments leading to practical clinical applications in the field of addiction.

Opioid and other peptides as inhibitors of leumorphin (dynorphin B-29) converting activity

A thiolprotease from rat brain membranes was shown to convert synthetic dynorphin B-29 (Dyn B-29, "leumorphin") to the tridecapeptide dynorphin B (Dyn B, "rimorphin"). This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. The dynorphin converting activity displayed typical Michaelis-Menten kinetics with an apparent Km for the substrate of 0.58 microM. Surprisingly, a synthetic peptide, Dyn B-29-(9-22), which contains the cleavage site, did not inhibit the activity. Dyn A inhibited the activity competitively with an apparent Ki of 3.7 microM. The converting activity was also inhibited by Dyn A-(6-17) but not by Dyn A-(8-17), suggesting a role of Arg6-Arg7 in the inhibition of converting activity. Bovine adrenal medulla Peptide E inhibited the converting activity substantially whereas metorphamide did not, suggesting the importance of COOH-terminal residues in recognition. Beta-Endorphin was an effective inhibitor of converting activity, and [alpha-N-acetyl]beta-endorphin was not, indicating a crucial role of the free NH2-terminus in recognition by the enzyme. ACTH inhibited the activity competitively with an apparent Ki of 39 nM. The converting activity was also inhibited substantially by ACTH-(1-13) but not by alpha-MSH, again indicating a requirement of the free NH2-terminus for recognition. The above results suggest that the converting enzyme recognizes peptides of the three known opioid gene families.

Neuropeptide processing by single-step cleavage: conversion of leumorphin (dynorphin B-29) to dynorphin B

Dynorphin B (rimorphin) is formed from dynorphin B-29 (leumorphin) by the action of a thiol protease from rat brain membranes. This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. In isotope dilution experiments we find that the radioactivity from radiolabelled dynorphin B-29, which appears in dynorphin B during incubation with the enzyme preparation, is not diminished by addition of a high concentration of dynorphin B-Arg14. Moreover, in pulse-chase experiments, radioactivity that appeared in dynorphin B-Arg14 did not decrease, nor did the radioactivity in dynorphin B increase, after chasing with a high concentration of non-radioactive dynorphin B-29. These results indicate that although some dynorphin B-Arg14 is formed by the impure enzyme preparation, it is not an intermediate in the conversion of dynorphin B-29 to dynorphin B. Thus the formation of dynorphin B does not involve the action of a trypsin-like enzyme followed by removal of arginine-14 by a carboxypeptidase B-like enzyme. It appears that a single enzyme converts dynorphin B-29 to dynorphin B in a single step.

Morphine and other opiates from beef brain and adrenal

We describe nonpeptide opioids found in extracts of beef hypothalamus and adrenal, which are recognized by antisera raised against morphine. Four have been purified to homogeneity. One is morphine. The structures of the other three have not been determined yet. None of them are derived from morphine or normorphine after extraction from the tissues. It is not known whether the opiates described here are of endogenous or exogenous origin.

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.

A monoclonal antibody specific for a dynorphin precursor

Murine monoclonal antibodies were produced against dynorphin-32 (D32), a naturally occurring opioid peptide containing the sequence of dynorphin A (Dyn A) at its amino terminus, followed by Lys-Arg, then by the sequence of dynorphin B (Dyn B). Initial characterization using an enzyme-linked immunosorbent assay revealed that one clone (17.M) recognized D32 but not Dyn A or Dyn B. A solid-phase radioimmunoassay using 125I-labeled antibody 17.M was developed and showed a maximum sensitivity of 45 fmol for synthetic D32. Dyn B crossreacted only 0.05%; Dyn A and other related opioid peptides crossreacted less than 0.001%. Immunoreactive D32 was detected in extracts of rat brain and anterior pituitary but not neurointermediate lobe of pituitary. The unique specificity of monoclonal antibody 17.M should make it useful in investigations of the differential localization and release of Dyn A and Dyn B and the precursor D32.

A linkage analysis of the Gm locus and multiple sclerosis

We conducted linkage analyses of immunoglobulin G heavy chain marker (Gm) phenotypes and multiple sclerosis (MS) in 30 families, each having at least two first-degree relatives with definite/probable MS. These families yielded positive evidence for linkage to human leukocyte antigen (HLA) loci in previous analyses. In the present analysis, however, the results for Gm were negative. Most lod scores were negative, particularly at the smaller recombination values (theta). We explored the possibility of heterogeneity by subgrouping our data on the basis of specific HLA types (A3, B7) and Gm types (Gm1, Gm1,2) within the pedigrees. The results were again negative with no substantial differences in estimates of theta between subgroups.

Antinociception and paralysis induced by intrathecal dynorphin A

Intrathecal administration of dynorphin A in rats produced dose-dependent antinociceptive effects in the tail-flick test to radiant heat and on a limb-flexion test to pressure. The potency of dynorphin A as an analgesic agent on the tail-flick test was dependent upon the duration of cannula implantation. When a short-term procedure was used (drug injected 1 day after catheter implantation) dynorphin A was approximately equipotent to morphine, whereas in animals with long-term implants (drug injected 7 or more days after catheter implantation) dynorphin A was an order of magnitude less potent than morphine. [D-Ala2,D-Leu5]enkephalin was the most potent opioid tested, and in the tail-flick test (long-term procedure) it was about 2 orders of magnitude more potent than dynorphin A and 7 times more potent than morphine. [Leu]enkephalin had no detectable antinociceptive effects. Low doses of naloxone (1 and 2 mg/kg s.c.) completely blocked the antinociceptive effects of morphine and [D-Ala2,D-Leu5]enkephalin, but neither low nor high (40 mg/kg s.c.) doses clearly blocked the antinociceptive effects of dynorphin A. Thus, dynorphin A has an antinociceptive action at the level of the spinal cord, and mu opioid receptors do not mediate these effects. In addition, high doses of dynorphin A (20 nmol or greater) produced long-lasting hindlimb paralysis, which suggests that dynorphin peptides may play a role in motor function in the spinal cord. This paralytic action of dynorphin A was not antagonized by naloxone in doses up to 32 mg/kg s.c.

Opioid receptor reserve in normal and morphine-tolerant guinea pig ileum myenteric plexus

We have measured the opioid receptor reserve in the guinea pig ileum myenteric plexus by means of the site-directed alkylating agent, beta-chlornaltrexamine. Treatment of the tissue with low (less than 10 nM) concentrations of beta-chlornaltrexamine caused a parallel shift of the log concentration-response curves for both normorphine and dynorphin A-(1-13). Analysis of the resulting curves indicated that the Kd values were 1.5 +/- 0.5 X 10(-6) and 10 +/- 4 X 10(-9), respectively. Using the naloxone Ke to distinguish between the mu and kappa receptors in this tissue, we found that the receptor selectivities of normorphine and dynorphin A-(1-13) were unchanged after a maximum parallel shift, thus demonstrating that there are both spare mu and spare kappa receptors present. The spare-receptor fraction for both receptor types was about 90%. In morphine-tolerant preparations (chronic pellet implantation), there was an apparent reduction in the fraction of spare mu receptors without any change in the apparent affinity of normorphine. Reduction in the spare receptor fraction does not necessarily imply reduction in the number of binding sites. We suggest that this reduction in receptor reserve is the basis of opioid tolerance, since the agonist concentration needed to produce a given effect is expected to increase as the receptor reserve decreases.

Nicotine self-administration in rats

Female Wistar rats were allowed to self-administer nicotine solutions through indwelling jugular vein cannulae for 23 h per day for periods from three to five weeks. Two response levers were available to the rats; responding on one lever, designated the active lever, produced an immediate infusion of nicotine solution or saline. A second lever for which responding had no programmed consequences was introduced as a control for the locomotor stimulant action of low doses of nicotine. Baseline lever response rates were determined over a period of one week, in which active lever responding produced an infusion of saline. Rats were then allowed access to varying doses of nicotine or saline for a further two or three weeks. Response rates on the active lever increased significantly in rats with access to nicotine at a dose of 30 micrograms kg-1 per response. However, control lever response rates were also significantly elevated. The role of nicotine-induced locomotor stimulation in the self-administration behaviour was further evaluated in a dose-reduction experiment, in which the dose of nicotine available to rats responding for 30 micrograms kg-1 per response was reduced to 3 micrograms kg-1 per response. This resulted in a significant differential increase in active lever responding relative to control lever responding. The results suggest that nicotine is positively reinforcing in rats which had not previously been deprived of food or water or received prior drug treatment, but also indicate that nicotine induced locomotor stimulation may contribute to the observed increases in lever response rates when rats self-administer nicotine.

Naltrexone treatment of heroin addiction: one-year follow-up

Pre-treatment characteristics and post-treatment outcome measures were compared for 40 patients who began naltrexone maintenance and 77 who did not after a 6-month period of temporary maintenance on L-alpha-acetylmethadol (methadyl acetate LAAM). Patients who chose to begin naltrexone were younger, had fewer incarcerations and fewer months incarcerated prior to LAAM treatment, had fewer opiate-free months following previous treatments, and were more likely to be of Caucasian ethnicity. One year later, significantly more patients who had received any naltrexone than those who had not were no longer in any treatment program and were opiate-free. We found no significant correlations between total duration of naltrexone-treatment and post-treatment outcome variables such as heroin use, arrests, incarcerations or enrollment in a treatment program.

Improved control of bulky prostate carcinoma with sequential estrogen and radiation therapy

Patients with bulky prostate cancer have usually been treated by palliative measures because the likelihood of tumor control with definitive irradiation has been low and the development of distant metastases high. The addition of estrogen to irradiation has not been shown to be of value. However, we believe the method of estrogen administration may have been the cause for the apparent lack of benefit. Estrogen had been started either concurrent with irradiation or had been used for palliation and was given for long and unscheduled time periods prior to irradiation. We have used estrogen for two months prior to and concurrent with irradiation. We postulated that in those patients with estrogen responsive cancer, the reduced tumor burden prior to irradiation could enhance tumor control and survival. Between 1975 and 1980, 25 patients with bulky prostate cancer received sequential estrogen and irradiation, 12 patients irradiation alone and six patients irradiation after having become refractory to long-term estrogen use. One patient was lost to follow-up. Eighteen of 25 (72%) treated by sequential estrogen and irradiation, 14/17 (82%) with estrogen responsive cancer and 4/8 (50%) with estrogen resistant cancer had a complete tumor response. Six of 11 (55%) patients treated by irradiation alone and 2/6 (33%) treated by irradiation for estrogen refractory cancer had a complete tumor response. Disease-free survival was observed in 13/25 (52%) treated by sequential estrogen and irradiation, and 8/17 patients (47%) with irradiation. It is also possible the improved survival in the estrogen responsive group was a direct result of improved local control. Persistent local disease can act as a source for distant metastases. Distant metastases was observed in 15% of patients when the primary tumor was controlled and 30% when there was persistent or recurrent local disease. Also, progressive local disease can be an important cause of death. This was most evident in our patients with estrogen refractory cancer. Almost all patients in this group had progressive local disease that caused serious urinary bleeding and urinary infection that were considered the major cause of death. Our results suggest bulky prostate cancer should be aggressively treated when first diagnosed. The value of adjunct estrogen is unproven. Our results with the use of estrogen prior to and concurrent with irradiation is encouraging. Estrogen may shrink the cancer and allow for a more favorable geometry for external irradiation. Tumor control and survival may be thereby improved.(ABSTRACT TRUNCATED AT 400 WORDS)

Site-directed alkylation of multiple opioid receptors. I. Binding selectivity

We report a method for measuring and expressing the binding selectivity of ligands for mu, delta, and kappa opioid binding sites. We used radioligands that are partially selective for these sites in combination with membrane preparations enriched in each site. Enrichment was obtained by treatment of membranes with the alkylating agent beta-chlornaltrexamine in the presence of appropriate protecting ligands, sufentanil for mu sites, [D-Ala2, D-Leu5] enkephalin for delta sites, and dynorphin A for kappa sites. After enrichment for mu receptors, [3H] dihydromorphine bound to a single type of site as judged by the slope of competition binding curves. After enrichment for delta or kappa receptors, binding sites for [3H] [D-Ala2, D-Leu5]enkephalin and [3H]ethylketocyclazocine, respectively, were still not homogeneous. There were residual mu sites in delta-enriched membranes but we found no evidence for residual mu or delta sites in kappa-enriched membranes. We used this method to identify ligands that are highly selective for each of the three types of sites: Tyr-D-Ala-Gly-(Me)Phe-Gly-ol, sufentanil, and morphiceptin for mu sites; (D- Pen2 , D- Pen5 ]enkephalin and [D- Pen2 ,L- Pen5 ]enkephalin for delta sites; and tifluadom and U50 ,488 for kappa sites.

Site-directed alkylation of multiple opioid receptors. II. Pharmacological selectivity

A site-directed alkylating agent was used to inactivate one or more types of opioid receptor in two bioassay preparations in the presence of type-selective ligands as protectors of other opioid receptor types. Since the pharmacological potency of an agonist is decreased when the receptor type through which it acts has been inactivated, the method can be used to characterize the pharmacological selectivity of opioid agonists. All of the smaller opioid products of the enkephalin gene were found to be delta-selective in the mouse vas deferens, but BAM-12P, BAM- 22P , and Peptide E were not. In the same tissue, beta c-endorphin was not mu-selective, but in the guinea pig ileum preparation it evidently combined with mu and kappa receptors. The presence of functional epsilon receptors, however, could not be ruled out. The approach described here is applicable to any pharmacologically active receptors of which there are multiple types, and for which site-directed alkylating agents and type-selective protector ligands are available.

Analgesia induced by intrathecal injection of dynorphin B in the rat

A dose-dependent analgesic effect of intrathecally injected dynorphin B was observed in rats using the tail flick as nociceptive test. Intrathecal injection of 20 nmol of dynorphin B increased the tail flick latency by 90 +/- 23%, an effect that lasted about 90 min. For the same degree of analgesia, dynorphin B was 50% more potent than morphine on a molar basis. The analgesic effect of this dose of dynorphin B was partially blocked by 10 mg/kg, but not by 1 mg/kg, of subcutaneous naloxone, showing a relative resistance to naloxone reversal as compared with morphine analgesia. The analgesia produced by dynorphin B was unchanged in morphine-tolerant rats but was significantly decreased in rats tolerant to ethylketazocine. These results suggest that dynorphin B produces its potent analgesic effect by activation of kappa rather than mu opioid receptors in the rat spinal cord.