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Biomedical subjects

F Nyberg

Publications and source records attributed to F Nyberg.

At least 217 records · Page 12Linked to original sources
PubMed1988

Cerebrospinal fluid activity of dynorphin-converting enzyme at term pregnancy.

Cerebrospinal fluid activity of a dynorphin-converting enzyme transforming prodynorphin-derived peptides to [Leu]enkephalin-Arg6 was measured in 12 women at term pregnancy before cesarean section and in eight nonpregnant, nonpuerperal controls. In pregnant women, the dynorphin-converting enzyme activity was significantly lower (mean +/- SD 6.8 +/- 3.8 U/L) than in nonpregnant controls (11.7 +/- 2.6 U/L; P less than .01). Furthermore, prodynorphin-derived [Leu]enkephalin-Arg6-containing polypeptides were significantly increased in samples from pregnant women (P less than .05). This indicates that a reduced activity of opioid peptide-degrading enzymes might contribute to an increased resistance to pain at term pregnancy.

Cesarean Section↗
PubMed1987

Characterization of a substance P-Gly12 amidating enzyme in human cerebrospinal fluid.

Enzyme activity capable of converting the glycine-extended substance P precursor, substance P-Gly12, into substance P was purified from human cerebrospinal fluid. The conversion reaction was monitored by radioimmunoassay measurement of substance P formation. The chemical identity of the product was verified by reversed-phase HPLC. The enzyme reaction was stimulated by Cu(II) ion and ascorbic acid and inhibited by the presence of diethyldithiocarbamate. By HPLC molecular sieving, the major enzyme activity appeared as a protein of 26,000 molecular weight.

Chromatography, High Pressure Liquid↗
PubMed1987

Opioid peptides in man--analytical aspects.

The opioid peptides present extraordinary problems for analysis, since they are structurally homologous yet substantially different. Within each of the three systems, proopiomelanocortin, proenkephalin and prodynorphin, a whole set of peptides of successively smaller sizes are generated. The biological relevance of the different peptides is not fully understood. Analytical strategies may either be specifically directed to individual peptide species or to identification of total system output.

Endorphins↗
PubMed1987

Dynorphin A immunoreactivity in human cerebrospinal fluid.

Dynorphin A immunoreactivity in human cerebrospinal fluid has been characterized. Large quantities of the fluid were fractionated by molecular sieving on a Sephadex G-50 column and analyzed by radioimmunoassay. Active fractions were further analyzed by means of HPLC and an enzyme radioimmunoassay procedure for identification of Leu-enkephalin-Arg6 sequences. Several dynorphin A-active components of varying sizes were identified. However, most immunoreactive material derived from species of higher molecular weight (Mr 3000 and 5000) than authentic dynorphin A (Mr 2000). The Leu-enkephalin core was found to reside in both these large structures.

Chromatography, Gel↗
PubMed1987

Isolation of three electrophoretic variants of rat pituitary growth hormone.

A procedure has been developed for the isolation of rat pituitary growth hormone and for the subsequent resolution of the preparation into three variants by preparative electrophoresis. The starting material was whole frozen glands and the process involved homogenization and extraction at pH 6.2, ammonium sulfate fractionation and molecular-sieve chromatography on Sephadex G-100. The separation into charge variants was achieved by zone electrophoresis in agarose suspension at alkaline pH. The purification was monitored by radioimmunoassay and the specific activities were expressed in terms of the rat growth hormone reference preparation (RP-1) supplied by the NIADDK, Bethesda, U.S.A. The three-component preparation and its constituents all had activities in the same range, exceeding the activity of the reference by a factor up to 20 times. Bioassay of the three-component preparation, based on measurement of longitudinal bone growth in hypophysectomized rats gave a potency of 4-5 IU/mg. The reference was the 1st International Standard (bovine) for growth hormone. The yield of the three-component preparation was 3.3 mg per gram pituitary tissue. Different electrophoretic analyses revealed the efficiency of the preparative procedure in separating the variants. The results of the analyses also support the view that difference in electrophoretic behaviour is due to a difference of a single net charge between adjacent variants. In addition, growth hormone was prepared from two side extracts (at pH 7.0 and pH 9.8, respectively), provided by a procedure developed earlier for rat prolactin. The three preparations gave electrophoretic patterns of equal appearance although the relative proportions of the activity peaks differed.

Animals↗
PubMed1987

Respiratory and neuroendocrine responses of piglets to hypoxia during postnatal development.

Breathing response to 12% and 6% O2 in N2 (at isocapnia) was measured in anaesthetized piglets, 1-5 and 19-25 days old, before and after 3 mg kg-1 i.v. naltrexone. The degree of interaction between the anaesthetic and naltrexone was assessed. At the end of each hypoxic trial, arterial blood was sampled for measurements of pH and gas tensions, (Met)enkephalin-Arg6-Phe7, adenosine, noradrenaline and adrenalin. Whereas respiration in older animals was stimulated by hypoxia, young piglets had a biphasic response with a pronounced ventilatory decrease in response to severe hypoxia (6% O2/N2). In young animals there was a greater ventilatory response with naltrexone than without the drug, and the biphasic hypoxic response was ameliorated or reversed by naltrexone. Levels of adrenalin increased and those of encephalin, adenosine and noradrenaline tended to increase during hypoxia in the younger age group. Levels of adenosine showed significant increase when data from both age groups and levels of hypoxia were pooled. Combined with previously reported physiological evidence regarding adenosine in hypoxic depression, we conclude that the present results are compatible with a role of opioid peptides and adenosine in the early postnatal response to hypoxia.

Adenosine↗
PubMed1987

Endorphin activity in cerebrospinal fluid prior to elective cesarean section and in early puerperium.

Opioid activity in cerebrospinal fluid (CSF) was estimated by radioreceptor-assay (RRA) in samples obtained from ten women at term pregnancy and in the early puerperal period. The samples were fractioned on Sephadex G-10 columns and two opioid receptor active fractions, FI and FII, were recovered. Two pools of FII materials from pregnant and puerperal women, respectively, were further analyzed by electrophoresis and the concentrations of opioid activity were measured by radioreceptor assay. There was a significant rise in receptor-assayed FII opioid activity in late pregnancy as well as in the early puerperal period compared to that of healthy, nonpregnant, nonpuerperal females. Pooled FII material obtained before delivery could be separated into two major components tentatively assigned the hexapeptide [Met]enkephalin-Lys6 and the heptapeptide [Met]enkephalin-Arg6-Phe7. These two opioid peptides both have their origin in the [Met]enkephalin precursor, proenkephalin A. In the puerperal period there was predominance of only one of these components.

Adult↗
PubMed1987

Cerebrospinal fluid dynorphin1-17 and beta-endorphin in late pregnancy and six months after delivery. No influence of acupuncture treatment.

Cerebrospinal fluid (CSF) levels of dynorphin A and beta-endorphin were measured by radioimmunoassay in 62 primiparae in term pregnancy before onset of labour. In 50 of these women acupuncture (AP) treatment was given in an antenatal preparation procedure. In 15 of the AP-treated women, CSF samples were further obtained six months after delivery. Median values for dynorphin A were 7.5 pmol/l in AP-treated women and 6.4 pmol/l in non-treated controls. The puerperal median value for dynorphin A was 7.6 pmol/l. Median values for beta-endorphin were 7.1 pmol/l in AP-treated women and 5.7 pmol/l in non-treated controls. The median beta-endorphin value after delivery was 7.3 pmol/l. There was no significant difference in CSF dynorphin A or beta-endorphin levels between the AP-treated women and non-treated controls in late pregnancy. Consequently, the present study does not support the theory of a positive influence on either the dynorphin or the beta-endorphin system by manual AP. Within subject comparisons of dynorphin-A and beta-endorphin failed to indicate any significant trend in samples obtained in late pregnancy and 6 months after delivery, and there was no increased activity in either the dynorphin or the beta-endorphin system in late pregnancy, as reflected by CSF levels.

Acupuncture Therapy↗
PubMed1986

High-performance liquid chromatography and diode-array detection for the identification of peptides containing aromatic amino acids in studies of endorphin-degrading activity in human cerebrospinal fluid.

Diode-array UV detection has been adapted for analysis of opioid peptides and their metabolic fragments differing in aromatic amino acid content. In combination with high-performance liquid chromatography, the technique allowed a direct and rapid discrimination between peptides containing phenylalanine, tryptophan and tyrosine, or a combination of these residues. Enkephalin fragments with either tyrosine or phenylalanine, or both, were identified after digestion of the pentapeptide with proteolytic activity recovered from human cerebrospinal fluid. The N-terminal tyrosine-containing fragment of dynorphin A was identified after hydrolysis of the peptide by a cerebrospinal fluid endopeptidase. The study was extended to the analysis of some non-opioid peptides. The Tyr1 analogue of delta-sleep-inducing peptide was easily distinguished from the authentic compound with a tryptophan at the N-terminus. Results indicated that the technique was useful for discriminating between dipeptides differing in aromatic residues that were unresolved by high-performance liquid chromatography.

Amino Acids↗
PubMed1986

Enkephalin-containing polypeptides in human cerebrospinal fluid.

The chemical nature of peptides in human CSF with the enkephalin core sequence from proenkephalin A and proenkephalin B, was investigated. Direct measurements with radioimmunoassay (RIA) were run on enkephalin, enkephalin hexapeptides, dynorphin A, dynorphin A1-8 and dynorphin B. The hexapeptides occurred in about 3 times higher concentration than the corresponding enkephalins. The only dynorphin RIA which gave positive results was the one for dynorphin A. However, most dynorphin A immunoactive material showed higher apparent molecular weight (MW; 3 and 5 kdalton) than the standard (2 kdalton). To identify and quantitate every possible proenkephalin derived peptide with the enkephalin sequence, chromatographic fractions were treated with trypsin. The products, Leu-enkephalin-Arg6 (from proenkephalin B) and Met-enkephalin-Lys6/Arg6 (from proenkephalin A) were measured by specific RIAs and identified by HPLC. In the higher (greater than 5 kdalton) MW interval, there was about 10-fold higher yield of Met-enkephalyl than Leu-enkephalyl hexapeptides. In the intermediate 1-3 kdalton MW interval, most activity derived from proenkephalin B. Finally, from the low MW region, there was about 5 times more proenkephalin A peptides. The main dynorphin A peak at 5 kdalton was transferred to a major Leu-enkephalin-Arg6 peak by trypsin degradation. The data indicate the presence of a whole family of peptides from the two proenkephalin genes in human CSF. Precursors to the peptides supposed to be the active members in the proenkephalin families occur in relatively high concentrations and may provide good markers for activity in these peptide systems.

Chromatography, Gel↗
PubMed1986

Assay and biochemical characterization of a dynorphin converting enzyme in human cerebrospinal fluid.

An endopeptidase hydrolyzing dynorphins A and B and alpha-neo-endorphin at the Arg6-Arg7 or Arg6-Lys7 bonds, was partially purified from human cerebrospinal fluid and further characterized by various biochemical techniques including HPLC gel permeation (UltroPac TSK G3000SW) and ion exchange (TSK DEAE-3SW) chromatography. A procedure for quantitative analysis of the enzyme in individual CSF samples is also described. The activity in lumbar CSF of women in late pregnancy was significantly lower than that in control samples.

Amino Acid Sequence↗
PubMed1986

[Met]enkephalin-Arg6-Phe7 in human CSE--increased levels in late pregnancy.

The opioid heptapeptide, [Met]enkephalin-Arg6-Phe7 was measured in CSF of women at term pregnancy and during the luteal phase by RIA. Levels turned out to be significantly increased in pregnant women. These results are in agreement with an earlier paper in which we reported increased levels of receptorassayed opioid peptides deriving from proenkephalin A in CSF of women in term pregnancy compared to levels in nonpregnant, nonpuerperal women.

Chromatography, High Pressure Liquid↗
PubMed1985

Endopeptidase in human cerebrospinal fluid which cleaves proenkephalin B opioid peptides at consecutive basic amino acids.

An endopeptidase releasing the common N-terminal hexapeptide, (Leu)-enkephalin-Arg6, from dynorphins A and B, and alpha-neoendorphin was purified from human cerebrospinal fluid. Purification involved ion-exchange chromatography (DEAE-Sepharose CL-6B), hydrophobic interaction chromatography (phenyl-Sepharose CL-4B) and molecular sieving (Sephadex G-100). The enzyme showed molecular heterogeneity. A major fraction had an apparent molecular weight of about 40,000. It had an optimum activity in the pH range of 6-8. The conversion of dynorphin A was not affected by EDTA or iodoacetate but strongly reduced in the presence of phenylmethyl-sulphonyl fluoride, suggesting the enzyme is a serine protease.

Amino Acids↗