Agonist-induced state of the delta-opioid receptor that discriminates between opioid peptides and opiate alkaloids

We report a novel agonist-induced change in delta-opioid receptor binding properties in NG108-15 cells. Pretreatment of these cells with opioid agonists substantially diminishes the binding of peptide agonists and a peptide antagonist to opioid receptors in intact cells or membrane preparations. However, similar agonist-induced changes in the binding of opiate alkaloid agonists and antagonists were not detected. The change in opioid peptide binding occurs rapidly at 37 degrees (t1/2 approximately 10 min) but is not induced by agonist treatment at 4 degrees. Because of its lability at 37 degrees, the binding change is only detected when equilibrium binding assays are performed at 4 degrees. Both alkaloid and peptide agonists induce the binding change in a dose-dependent manner, with an ED50 for etorphine of approximately 10 nM. The induction of the binding change is completely blocked by the opiate antagonist naloxone. Stimulation of muscarinic receptors (which, like opioid receptors, inhibit adenylate cyclase in these cells) does not induce or block the binding change. These data reveal the operation of a homologous regulation mechanism that rapidly diminishes the interaction of delta-subtype opioid receptors with peptide ligands but does not detectably change the interaction of receptors with alkaloid ligands.

The measurement of silicon in a lung phantom--a comparison of two nuclear reactions for in vivo activation analysis

The amount of silica in the human lung may be estimated by measurement of silicon using in vivo neutron activation analysis. A pulsed, fast neutron beam, produced with a 2 MV Van de Graaff generator using the 2H + 2H reaction, was used to irradiate a Si-doped chest phantom in order to determine minimum detection limits (MDL). Two 'in-beam' nuclear reactions on Si were studied; prompt fast neutron inelastic scatter 28Si (n,n' gamma)28Si reaction was measured during the beam burst and the slow neutron prompt capture reaction was measured between the fast neutron bursts. Although the latter reaction appeared less favourable due to neutron cross section and measurement efficiency considerations, it yielded an MDL of 1.8 g compared with 2.3 g for the 28Si(n,n' gamma)28Si reaction. A comparison was made with a 252Cf neutron irradiation system where a Si MDL of 6.3 g was obtained using the slow neutron capture reaction. The Van de Graaff system permits 'exposed' Si lung burdens to be measured but not normal levels. Improved measurement sensitivity may be achieved by reduction of high counting-rate losses and high background radiation.

Cloning of a delta opioid receptor by functional expression

Opiate drugs have potent analgesic and addictive properties. These drugs interact with receptors that also mediate the response to endogenous opioid peptide ligands. However, the receptors for opioids have eluded definitive molecular characterization. By transient expression in COS cells and screening with an iodinated analog of the opioid peptide enkephalin, a complementary DNA clone encoding a functional delta opioid receptor has been identified. The sequence shows homology to G protein-coupled receptors, in particular the receptors for somatostatin, angiotensin, and interleukin-8.

Multicenter evaluation of the novel ABN Western blot (immunoblot) system in comparison with an enzyme-linked immunosorbent assay and a different Western blot

A new, modular Western blot (immunoblot) system for human immunodeficiency virus (HIV) antibodies (ABN WesPage; Wellcome) was compared with enzyme immunoassays (Wellcome, Behringwerke, and Abbott) and with a U.S. Food and Drug Administration (FDA)-licensed Western blot (DuPont) in a multicenter study. A total of 649 serum samples from HIV patients at different stages of the disease, as well as from high-risk patients, from patients with conditions unrelated to AIDS, and from healthy blood donors, were used in the evaluation along with nine seroconversion panels. For evaluation of Western blot reactivity, both Centers for Disease Control (CDC) and FDA criteria were used. With the DuPont Western blot as the reference assay, the overall sensitivity and specificity of the ABN WesPage were 100 and 99.1%, respectively, when indeterminate results were not taken into account and when both tests were interpreted in accordance with CDC criteria. The DuPont Western blot detected significantly more antibodies to pol and gag gene products than the ABN WesPage. The ABN WesPage showed a higher positive rate of detection of viral envelope band gp160. When both Western blots were interpreted in accordance with CDC criteria, the ABN WesPage and the DuPont Western blot yielded 9.3 and 10.4% indeterminate results, respectively. When the DuPont Western blot was interpreted in accordance with the manufacturer's instructions (FDA criteria), 25.7% of the samples tested were regarded as indeterminate. The choice of interpretation criteria is of paramount importance for the evaluation of HIV Western blot patterns.

Focal stimulation of the mossy fibers releases endogenous dynorphins that bind kappa 1-opioid receptors in guinea pig hippocampus

Physiological release of endogenous opioids in guinea pig hippocampal slices was detected in an in vitro competition binding assay using [3H]U69,593, a kappa 1-selective radioligand. Veratridine-induced opioid release caused a decrease in [3H]U69,593 binding that was blocked by either tetrodotoxin addition or the removal of calcium from the incubation buffer. Focal electrical stimulation of opioid peptide-containing afferent pathways resulted in a decrease in [3H]U69,593 binding, whereas stimulation of a major afferent lacking endogenous opioid immunoreactivity had no effect. The addition of 6-cyano-7-nitroquinoxaline-2,3-dione blocked the reduction in [3H]U69,593 binding caused by perforant path stimulation, but not the reduction caused by mossy fiber stimulation, suggesting that the primary source of endogenous kappa ligands was likely to be the dentate granule cells. Antisera against dynorphin A(1-8) or dynorphin B peptides inhibited the effects of mossy fiber stimulation in the [3H]U69,593 displacement assay. Antisera against other prodynorphin- and proenkephalin-derived opioid peptides had no effect. As shown by receptor autoradiography, the distribution of kappa 1 binding sites was limited to the molecular layer of the dentate gyrus and the presubiculum region of temporal hippocampal slices. These results indicate that prodynorphin-derived opioids released under physiological conditions from the mossy fibers act at kappa 1 receptors in the guinea pig dentate gyrus.

Postmortem changes in rat brain extracellular opioid peptides revealed by microdialysis

Microdialysis combined with a solid-phase radioimmunoassay was used to monitor changes in extracellular opioid peptide levels in the rat globus pallidus/ventral pallidum as a result of terminal brain ischemia. Ischemia was induced by anesthetic overdose or by severance of blood vessels supplying the brain. In control animals the recovered immunoreactivity increased an average of 13-fold in the 30-min sample following anesthetic overdose. Perfusion of a calcium-free, 10 mM EGTA-containing medium through the dialysis probe significantly attenuated the amplitude of this response, with the average increase being only threefold. Shorter sampling intervals (5 min) indicated that release of opioid peptide material into the extracellular environment occurs within the first 5 min of ischemia resulting from severance of the blood supply to the brain. HPLC analysis identified the majority of the postmortem-induced immunoreactive material as Met- and Leu-enkephalin.

Isolation and characterization of opioid peptides from rabbit cerebellum

The rabbit cerebellum has been shown to contain significant quantities of opioid receptors consisting of both mu- and kappa-subtypes. To determine the nature of the endogenous opioid ligands in this tissue, extracts from rabbit cerebellum were separated by various chromatography techniques and fractions were assayed initially for opioid peptides with a radioimmunoassay capable of detecting all peptides with an amino-terminal Tyr-Gly-Gly-Phe sequence. This sequence is common to all mammalian opioid peptides and is critical for recognition by all known opioid receptors. Each of the three immunoreactive opioid peptide peaks detected was purified to homogeneity and subjected to amino acid composition and sequence analysis. One peak was analyzed further by mass spectrometry. This identified the major opioid peptides in the cerebellum as [Met5]enkephalin, [Leu5]enkephalin, and heptapeptide [Met5]enkephalyl-Arg6-Phe7. The comprehensiveness of this initial detection scheme in identifying biologically active opioid peptides was substantiated through subsequent analysis. Using specific radioimmunoassays for representative opioid peptides of the three opioid systems currently known, no other peptides of either the proenkephalin, proopiomelanocortin, or prodynorphin series were detected in any appreciable amounts. Collectively, these results are consistent with the position that rabbit cerebellar opioids are derived from proenkephalin. However, given that no appreciable quantities of either [Met5]enkephalyl-Arg6-Arg7-Val8-NH2 (metorphamide) or [Met5]enkephalyl-Arg6-Gly7-Leu8 were detected suggests that rabbit proenkephalin may have a slightly altered sequence and/or is differentially processed relative to other mammalian species studied.

Description of a home follow-up program for childbearing families

Over the years, nurses have identified the need for home follow-up of postpartum families after discharge from the hospital. In the current health-care environment, the need for follow-up care is greater than ever. This article reviews the rationale for a follow-up program and describes a model, in existence since 1987, that makes postpartum follow-up an integral part of the total nursing care that childbearing families receive from the institution. The purpose, objectives, components, organization, documentation, funding, and evaluation of the program are described.

Dual determination of extracellular cholecystokinin and neurotensin fragments in rat forebrain: microdialysis combined with a sequential multiple antigen radioimmunoassay

Microdialysis was combined with a highly sensitive sequential multiple antigen radioimmunoassay to simultaneously measure extracellular cholecystokinin and neurotensin fragments from discrete regions of the rat brain in vivo. The assay was conducted in 96-well plates and provided a limit of detection for both peptides of 0.1 fmol. Dialysis membranes composed of polyacrylonitrile, Cuprophan and polycarbonate were evaluated in vitro using both radiolabelled peptides and radioimmunoassay. Polycarbonate probes were implanted in the posterior medial nucleus accumbens-septum, medial caudate nucleus or medial prefrontal cortex of halothane-N2O-anaesthetized rats. Cholecystokinin immunoreactivity levels were generally above the assay detection limits (0.1-0.7 fmol) in 30-min samples from all three regions under basal conditions. Recovered basal amounts of neurotensin immunoreactivity were detectable in the nucleus accumbens-septum in approximately 50% of experiments (0.1-0.2 fmol) but were not measured in the caudate nucleus or prefrontal cortex. In the nucleus accumbens-septum, a 10-min pulse of 200 mM K(+)-containing artificial cerebrospinal fluid in the perfusion medium during a 30-min sampling period increased the recovered cholecystokinin and neurotensin immunoreactivity to 9.7 fmol +/- 1.9 S.E.M. and 5.8 +/- 1.6 S.E.M., respectively. A second stimulation following a 2.5-h interval produced similar elevations with S2:S1 ratios of 0.62 +/- 0.07 and 0.68 +/- 0.07 for cholecystokinin and neurotensin, respectively. In a separate series of experiments the second stimulation of both peptides was prevented by perfusion of a 10 mM EGTA-containing medium. Similar results were obtained in the caudate nucleus for cholecystokinin, but K(+)-induced elevations in neurotensin immunoreactivity were much smaller (0.5 fmol) in this brain region and calcium dependency was not established. Sequential K+ stimulations at 50, 100 and 200 mM produced progressively greater increases in recovered cholecystokinin and neurotensin immunoreactivity from the nucleus accumbens-septum and of cholecystokinin immunoreactivity from the prefrontal cortex. No neurotensin immunoreactivity was detected in the prefrontal cortex following K+ stimulation. Large post mortem increases in the recovered amounts of cholecystokinin and neurotensin immunoreactivity were observed. This effect was significantly attenuated by EGTA although there was a large calcium-independent component of the cholecystokinin immunoreactivity. On reverse-phase high-performance liquid chromatography the major cholecystokinin-immunoreactive peak co-eluted with sulphated cholecystokinin octapeptide. Neurotensin-immunoreactive material co-eluted with neurotensin (1-13), neurotensin (1-12), neurotensin (1-11), neurotensin (1-10) and neurotensin (1-8). These results further demonstrate the potential of microdialysis for studying neuropeptide release and metabolism in vivo when combined with sufficiently sensitive assay procedures.

Regulation of both preproenkephalin mRNA and its derived opioids by haloperidol--a method for measurement of peptides and mRNA in the same tissue extract

The goal of this study was to delineate the effects of dopamine antagonists on the regulation of preproenkephalin mRNA and opioid peptides in the rat brain. We have developed a method whereby both mRNA and peptides can be efficiently measured in the same tissue extract, thus reducing the effects of intraspecies variation, differences in dissection and the number of animals required for statistical significance. A sub-chronic dose of haloperidol (3 mg/kg given i.p. in 100 microliters DMSO daily for 5 days) produced a 1.8-fold increase (P less than 0.001) in striatal preproenkephalin mRNA levels when compared to animals injected with vehicle dimethyl sulfoxide (DMSO) employing the same schedule. Total opioid peptides as measured by a radioimmunoassay directed to the N-terminus of enkephalins and endorphins were elevated 1.6 fold (P less than 0.001) in the rat striatum. However in other brain regions examined no increases were observed either in preproenkephalin mRNA or the tissue levels of opioid peptides. Analysis of the opioid-like immunoreactive peptides by reverse-phase HPLC analysis showed no dramatic changes in the ratios of the various opioid peptides between haloperidol and vehicle injected animals. Naive animals showed no statistical differences in opioid peptide levels compared to the haloperidol treated animals. There was a statistically significant decrease (30%) in the opioid peptide content of the animals injected with vehicle daily for 5 days when compared with the animals merely sacrificed, or those given acute injections (either with haloperidol or vehicle) the day of sacrifice.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo measurements of cadmium and lead in occupationally-exposed workers and an urban population

This paper reports the preliminary findings of a survey of lead and cadmium body burdens in a nonoccupationally exposed population in Swansea, Wales, using the techniques of in vivo neutron activation and X-ray fluorescence analysis. Some measurements on an occupationally cadmium-exposed group are also included. The results confirm the association between cadmium and smoking and bone lead and age. The in vivo measurements demonstrate a degree of comparability with other data, which supports the further detailed analysis of the relationships between body burden and exposure, on the one hand, and possible health effects on the other.

Measurements of total body calcium by prompt-gamma neutron activation analysis using a 252Cf source

A clinical neutron activation instrument has been developed for in vivo elemental analysis. Utilizing the prompt-capture gamma ray technique, simultaneous total body (TB) measurements of primarily Ca, but also Cl, N, C, and H are routinely performed. This paper describes a technique for the measurement of TBCa (g) that relies on the use of TBCl as an internal standard. The method has been tested with four anthropomorphic phantoms covering a range of body habitus. The mean discrepancy between the measured and known Ca contents was 3.6%. The technique has been applied to two patient groups, and encouraging results were obtained.

A three-dimensional reconstruction of metastatic adenocarcinoma in lymph node

Lymph nodes are a common site of metastatic cancer. The ability to view the three-dimensional configuration of complex biological structures, rendered in solid model form, might help to further elucidate the pathophysiology of metastatic disease. This paper presents a method for three-dimensional reconstruction from serial sections of a lymph node containing metastatic adenocarcinoma. The reconstruction and subsequent animation were carried out using the P3D graphics software (developed at the Pittsburgh Supercomputing Center) and rendered by the Dore high-speed renderer on an Ardent Titan graphics workstation. As different views of the model were produced, they were recorded a frame at a time on U-matic video tape. A three-dimensional solid-modeled object portrays metastatic, neoplastic elements within a lymph node.

Determination of total body calcium by prompt gamma neutron activation analysis: absolute in vivo measurements

Sequential TBCa measurements using the prompt gamma ray technique are firmly established and a number of patient groups are under investigation. A technique has been proposed for the absolute measurement of TBCa based upon the use of TBCl as an internal standard. Further work is needed to establish the validity of the method, but the initial results are encouraging.

Calibration and evaluation of a 252Cf-based neutron activation analysis instrument for the determination of nitrogen in vivo

A novel clinical instrument for multi-element in vivo neutron activation analysis has been recently constructed in Swansea. The instrument is intended primarily for prompt gamma measurement of total and partial body calcium, total body nitrogen and partial body cadmium. For the measurement of nitrogen the subject is scanned both prone and supine across a vertical collimated neutron beam from a 4 GBq 252Cf source. Two shielded Nal(TI) detectors, each of volume 2760 cm3, are placed above the subject on the opposite side to that irradiated. The prompt gamma ray spectrum contains prominent peaks from hydrogen, nitrogen, chlorine and carbon. The optimisation, calibration and evaluation of the instrument for the measurement of nitrogen, by the reaction 14N(n, gamma)15N, is described. The calibration corrects the ratio of nitrogen-to-hydrogen counts measured from the subject for background gamma rays and the effects of body habitus. Body hydrogen is use as as internal standard. Repeated measurements of a homogeneous anthropomorphic phantom indicate that the ratio of nitrogen-to-hydrogen counts may be determined by a coefficient of variation of 1.6% for a neutron dose equivalent incident on the phantom of 0.45 mSv (QF = 10). The accuracy of the calibration was assessed by measuring three anthropomorphic phantoms (weight range: 41.4-110 kg) containing simulated skeletons and the major organs of the body. For these phantoms the mean discrepancy of the measured to the known nitrogen content was +4.9%. The simultaneous measurement of chlorine and carbon is discussed.

Developmental expression of proenkephalin mRNA and peptides in rat striatum

The development of proenkephalin (PE) gene expression in the rat striatum was examined at the mRNA and peptide levels. Immunocytochemistry was performed with antisera generated to the PE-specific peptide product Met-enkephalin-Arg-Gly-Leu (MERGL). The distribution of immunostaining was compared with the distribution of PE mRNA, determined by in situ hybridization with an oligonucleotide probe. PE mRNA first appeared at E16 in the caudal ventrolateral striatum, followed at E17-18 by the appearance of MERGL immunoreactivity in a similar distribution. The anatomical gradients of PE gene expression were similar to the pattern of histogenesis of striatal neurons, suggesting that the timing of PE gene expression is related to the time of neuronal withdrawal from the mitotic cycle. The relation of the development of PE gene expression to the known patterns of striatal histogenesis, neurochemical compartmentalization and dopaminergic innervation is discussed.

Mass spectrometric charting of bovine posterior/intermediate pituitary peptides

The feasibility for charting neuropeptides in neuroendocrine tissues on the basis of the universal property and inherent specificity of their molecular weights was explored. As a model, a comprehensive MS analysis of extractable peptides from bovine posterior/intermediate pituitary was performed. Two suitable MS techniques--namely, plasma-desorption time-of-flight and fast atom bombardment MS--were evaluated, and each method could identify more than 20 peptides, including N-terminally acetylated and C-terminally amidated species. In toto these peptides account for almost the entire lengths of propressophysin, prooxyphysin, and proopiomelanocortin. Some of the experimentally determined molecular weights did not match any known peptides. Three of these species were identified as acidic joining peptide (4-24) [proopiomelanocortin(83-103)], C-terminal glycopeptide(22-39) [propressophysin(130-147)], and glycosylated C-terminal glycopeptide(1-19) [propressophysin(109-127)] by conventional sequence analysis.