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J Tang

Publications and source records attributed to J Tang.

At least 577 records · Page 32Linked to original sources
PubMed1984

Proglumide prevents and curtails acute tolerance to morphine in rats.

The antagonism of the antinociceptive action of morphine elicited by CCK-8-SO4 can be counteracted by proglumide, a CCK antagonist. The addition of morphine (10(-6)M) to the artificial spinal fluid perfusing the subarachnoidal space of rat spinal cord increases the CCK content of the perfusate. Proglumide can potentiate morphine analgesia without changing the half life of morphine. After seven to eight subcutaneous injections of morphine (4 mg/kg) repeated every two hrs there is tolerance to the antinociceptive action of morphine. Proglumide can partially block or reverse this acute tolerance to morphine.

Animals↗
PubMed1984

Depressor and natriuretic activities of several atrial peptides.

Mammalian atria contain peptides that have depressor and natriuretic activities. Four peptides, atriopeptin I to III (AP I to III) and alpha-human atrial natriuretic factor (alpha-hANP), were synthesized and assayed in the urethane-anesthetized rat for cardiovascular changes and natriuretic activities. All four peptides produced depressor responses and natriuresis. The relative activities were: alpha-hANP = AP III greater than AP II greater than AP I. The disappearance of iodinated AP III from plasma was rapid, with an estimated half-life of 2.5 min. Atriopeptin III was degraded by tissue homogenates, the relative activities being: kidney greater than liver greater than lung greater than plasma greater than heart. The HPLC profile of AP III suggested that smaller peptide fragments were formed after incubation with kidney homogenates. The degradation of AP III was inhibited by bestatin, an aminopeptidase inhibitor, and SQ 20881, a carboxypeptidase inhibitor.

Animals↗
PubMed1984

Amino acid sequence of porcine spleen cathepsin D.

The amino acid sequence of porcine spleen cathepsin D heavy chain has been determined and, hence, the complete structure of this enzyme is now known. The sequence of heavy chain was constructed by aligning the structures of peptides generated by cyanogen bromide, trypsin, and endo-proteinase Lys C cleavages. The structure of the light chain has been published previously. The cathepsin D molecule contains 339 amino acid residues in two polypeptide chains: a 97-residue light chain and a 242-residue heavy chain, with a combined Mr of 36,779 (without carbohydrate). There are two carbohydrate units linked to asparagine residues 70 and 192. The disulfide bond arrangement in cathepsin D is probably similar to that of pepsin, because the positions of six half-cystine residues are conserved. The active site aspartyl residues, corresponding to aspartic acid-32 and -215 of pepsin, are located at residues 33 and 224 in the cathepsin D molecule. The amino acid sequence around these aspartyl residues is strongly conserved. Cathepsin D shows a strong homology with other acid proteases. When the sequence of cathepsin D, renin, and pepsin are aligned, 32.7% of the residues are identical. The homology is observed throughout the length of the molecules, indicating that three-dimensional structures of all three molecules are similar.

Amino Acid Sequence↗
PubMed1984

Inhibition of spontaneous and opiate-modified nociception by an endogenous neuropeptide with Phe-Met-Arg-Phe-NH2-like immunoreactivity.

In rats the antinociceptive actions of morphine (injected intraventricularly) or of [Met5]enkephalin-Arg6-Phe7 (YGGFMRF) (injected intrathecally) were attenuated by a pretreatment with 10 microliter of artificial cerebral spinal fluid containing 1 microM captopril/1 microM bestatin/2.5 microM Phe-Met-Arg-Phe-NH2 (FMRF-NH2) given 5 min earlier by the same route. A high molecular weight form of FMRF-NH2 purified from bovine brain attenuated the antinociceptive action of YGGFMRF. IgG, prepared from a specific FMRF-NH2 antiserum, elicited a moderate antinociception reversible by naloxone; in contrast, IgG prepared from control serum failed to change tail-flick latencies. In rats receiving morphine every 2 hr and anti-FMRF-NH2 IgG every 4 hr, the antinociceptive action was still evident after eight successive injections; in rats receiving only morphine, the antinociceptive action had disappeared after six successive injections. Morphine (1 microM) added to the perfusion fluid of the subarachnoidal spaces of rat spinal cord releases FMRF-NH2-like peptides in the perfusate.

Animals↗
PubMed1984

Action of peptidase inhibitors on methionine5-enkephalin-arginine6-phenylalanine7 (YGGFMRF) and methionine5-enkephalin (YGGFM) metabolism and on electroacupuncture antinociception.

In the spinal cord Met5-enkephalin-Arg6-Phe7 (YGGFMRF) is located in small interneurons of the dorsal and ventral horns. From these storage sites, YGGFMRF can be released by perfusing the subarachnoidal spaces of the spinal cord with artificial spinal fluid containing substance P. In vitro YGGFMRF can be hydrolyzed readily by a dipeptidyl carboxypeptidase. In order to ascertain whether this reaction is physiologically relevant, we measured the content of YGGFMRF and Met5-enkephalin (YGGFM) in subarachnoidal space perfusate in presence and in absence of captopril, bestatin and thiorphan using substance P to activate the release of opioid peptides. Without peptidase inhibitors, the efflux of YGGFMRF and YGGFM was hardly detectable. The addition of captopril to the perfusion medium increased the substance P (10(-7) M)-induced release of YGGFMRF markedly but it increased the efflux of YGGFM to a much smaller extent. When captopril and bestatin were added together the amount of YGGFMRF present in the perfusate was further increased slightly. In contrast, the YGGFM content in the same perfusate was increased greatly by bestatin and only slightly by thiorphan. To characterize the pharmacological profile of these peptidase inhibitors, we compared electroacupuncture antinociception with and without intrathecal injections of captopril and bestatin. This antinociception, as measured by tail-flick latency, was potentiated by the intrathecal injection of captopril and bestatin. These results taken together suggest that YGGFMRF released in the perfusate of the arachnoidal space by substance P is metabolized by both dipeptidyl carboxypeptidase and aminopeptidase.

Acupuncture Therapy↗
PubMed1984

[Atripeptins].

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Amino Acids↗
PubMed1984

Increase of striatal Met5-enkephalin-Arg6-Phe7 (YGGFMRF) content elicited by long-term treatment with haloperidol.

In rats, daily doses of haloperidol repeated for various time periods increase striatal Met5-enkephalin-Arg6-Phe7 (YGGFMRF) immunoreactivity in a time- and dose-dependent manner. This increase occurred also in other dopamine-rich brain areas. After intraventricular captopril (0.5 mg), the accumulation rate of immunoreactive YGGFMRF was greater in haloperidol- than in saline-injected rats. Intraventricular captopril inhibits the YGGFMRF degradation; hence the greater accumulation rate of YGGFMRF caused by captopril in haloperidol-treated rats suggests that this drug increases the YGGFMRF biosynthesis. A slower rate of YGGFMRF release in haloperidol-treated rats can be excluded as a cause for the drug-induced increase in striatal content of this peptide because the release rates of YGGFMRF elicited by K+ were similar in striatal slices of haloperidol- and saline-treated rats. The similarities between the accumulation rate of immunoreactive YGGFMRF and of Met5-enkephalin induced by haloperidol suggest that haloperidol increases the biosynthesis of the specific messenger RNA for preproenkephalin, an opioid peptide precursor, which contains one copy of YGGFMRF and several copies of Met5-enkephalin.

Animals↗
PubMed1984

Ambulatory surgery.

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Ambulatory Surgical Procedures↗
PubMed1983

Met5-enkephalin-arg6-phe7 content of human and rabbit plasma.

Using an adsorption technique combined with high pressure liquid chromatography and a specific radioimmunoassay, the met5-enkephalin-arg6-phe7 (YGGFMRF) content was measured in human and rabbit plasma. This heptapeptide content was 0.16 +/- 0.03, 0.20 +/- 0.05 pmol/10 ml plasma, for human and rabbit plasma, respectively. The degradation of YGGFMRF injected intravenously (rabbit) or that of the opioid heptapeptide added to rabbit plasma is rapid. The biological half life (T 1/2) of 125I-YGGFMRF in rabbit plasma was about 45 seconds (in vivo) and 1 minute and 8 seconds (in vitro). The metabolic clearance rate of YGGFMRF is slower than that of met5-enkephalin. The YGGFMRF content of rabbit plasma increased following inhibition of dipeptidyl peptidase activity by an intravenous injection of captopril. The presence of met5-enkephalin-arg6-phe7 into circulation indicates that it may have some physiological role, however it is unknown whether circulating YGGFMRF originates from adrenal medulla, intermediate lobe of pituitary or some other site.

Adult↗
PubMed1983

Amino acid sequence of porcine spleen cathepsin D light chain.

The complete amino acid sequence of the light chain of cathepsin D from porcine spleen has been determined. The light chain consists of a single polypeptide chain with 97 amino acid residues. The sequence is: (formula; see text) The molecular weight of the light chain was calculated from this sequence to be 10,548 (without carbohydrates). A single disulfide bond links two half-cystine residues between positions 46 and 53. A cysteine residue is located at position 27. The light chain sequence is extensively homologous to the NH2-terminal sequence of other aspartyl proteases. It shows a 59% identity with the sequence of mouse submaxillary gland renin and a 49% identity with that of porcine pepsin. A single glycosylation site is located at residue 70 of the cathepsin D light chain. This site corresponds to position 67 of pepsin by homology. The active site aspartyl residue, corresponding to Asp-32 of pepsin, is located at residue 33 in the cathepsin D light chain.

Amino Acid Sequence↗
PubMed1983

Met5-enkephalin-arg6-phe7 and its receptor in lung.

The presence of met5-enkephalin-arg6-phe7 (YGGFMRF) and opiate receptors in rat, guinea pig and human lung was investigated with specific and sensitive radio immuno- and radio-receptor assays. 1) High and low molecular weight YGGFMRF-like immunoreactivity were detected in lung extracts using Bio-Gel P-2 column chromatography followed by radioimmunoassay. Using HPLC, we determined that the low molecular weight YGGFMRF-like immunoreactivity is authentic YGGFMRF. 2) The contents of YGGFMRF were 0.68 +/- 0.08, 0.76 +/- 0.12 and 0.63 pmol/mg protein in lung of rat, guinea pig and human, respectively. In the lung of these three species, the content of YGGFMRF is much greater than that of met5-enkephalin. 3) 47 mM KCl released YGGFMRF from rat lung slices in a Ca++ dependent manner. 4) Rat lung membranes were shown to bind [3H]-etorphine in a saturable manner. There are two populations of binding sites with a Kd = 0.6 and 7.1 nM and a Bmax = 7.8 and 28.5 fmol/mg protein, respectively. This binding could be displaced by YGGFMRF with high affinity, the other endogenous opioid peptides were poor displacers. From these results, we infer that YGGFMRF might be a putative neurotransmitter or neuromodulator, its role in the regulation of lung function can now be investigated.

Animals↗
PubMed1983

Oligosaccharide units of lysosomal cathepsin D from porcine spleen. Amino acid sequence and carbohydrate structure of the glycopeptides.

The amino acid sequences near the glycosylation sites and the oligosaccharide structures have been determined for the lysosomal protease cathepsin D from porcine spleen. Cathepsin D light and heavy chains were separately digested with proteases and the glycopeptides were purified. A single sequence was constructed from the amino acid sequence of the light chain glycopeptides which is: Tyr-Asn-Ser-Gly-Lys-Ser-Ser-Thr-Tyr-Val-Lys-Asn(CH2O)-Gly-Thr-Thr-Phe. A single glycopeptide sequence was also obtained for the heavy chain: Lys-Gly-Ser-Leu-Asp-Tyr-His-Asn(CH2O)-Val-Thr-Arg-Lys-Ala-Tyr. The light chain sequence is homologous with the sequence of porcine pepsin from residues 56 to 71. The heavy chain sequence is homologous with the pepsin sequence from residues 176 to 189. Thus, the 2 oligosaccharide-linked asparagines in cathepsin D correspond to residues 67 and 183 in pepsin and other homologous aspartyl proteases. These positions are located on the surface of the crystal structures of aspartyl proteases. Five oligosaccharides linked to Asn-67 were separated and their structures determined with proton NMR. Four major oligosaccharides are structural variants from the high mannose-type having 3, 5, 6, and 7 mannoses, respectively. A minor structure contained a third GlcNAc. Three oligosaccharide structures were found linked to Asn-183. Two major oligosaccharides are of the high mannose-type each with 5 mannose residues. One of the two contains a fucose linked to a GlcNAc. A third, very minor oligosaccharide contains galactose.

Amino Acid Sequence↗
PubMed1983

The effect of peptidase inhibitors on the release of Met5-Enk-Arg6-Phe7 (YGGFMRF) and Met5-enkephalin (YGGFM) from spinal cord induced by substance P in vivo.

Using a preparation for the perfusion of the subarachnoidal spaces of the spinal cord of rats it was found that substance P can stimulate the release of YGGFMRF and YGGFM. We have studied the effect of several peptidase inhibitors (captopril, bestatin, thiorphan) on the recovery of YGGFMRF and YGGFM released from spinal cord by substance P. The recovery of released YGGFMRF was increased by adding captopril to the perfusion medium. A combination of captopril and bestatin in the perfusion medium further increases this YGGFMRF recovery. Intrathecal injection of captopril and bestatin also potentiated the analgesic effect of YGGFMRF and electroacupuncture. These results suggest that substance P may act as a "releaser" of enkephalins in spinal cord and that the dipeptidyl carboxypeptidase and aminopeptidase may be important in the degradation of YGGFMRF in vivo.

Animals↗
PubMed1983

Substance P stimulates the release of Met5-enkephalin-Arg6-Phe7 and Met5-enkephalin from rat spinal cord.

Substance P (10(-6) M) injected in the fluid perfusing the subarachnoidal spaces of the spinal cord can release met5-enkephalin (YGGFM) and met5-enkephalin-Arg6-Phe7 (YGGFMRF) from spinal cord. This effect is Ca2+ dependent and can be blocked by the substance P antagonist, D-pro2, -D Trp7,9-substance P. The release of YGGFM and YGGFMRF was not observed when substance P was replaced by substance P1-9. These results suggest that substance P receptors are involved in triggering the release of enkephalins.

Animals↗
PubMed1983

Characterization and location of Met5-enkephalin-arg6-phe7 stored in various rat brain regions.

A specific antiserum against met5-enkephalin-arg6-phe7 was raised and used to study the distribution and characterization of met5-enkephalin-arg6-phe7-like immunoreactive material in rat brains by radioimmunoassay and immunohistochemical procedures. The antiserum appears to be directed to the COOH-terminus of the peptide, as it fails to cross-react with met5-enkephalin, met5-enkephalin-arg6, met5-enkephalin-arg6-arg7, met6-enkephalin-lys6, and leu-enkephalin. However, it cross-reacts with phe-met-arg-phe by about 10% and with phe-met-arg-phe-NH2 to an insignificant degree. The highest content of met5-enkephalin-arg6-phe7 was found in the striatum, which contains a dense network of immunoreactive varicose fibers and terminals, as well as immunoreactive cell bodies. The met5-enkephalin-arg6-phe7 in striatum can be released in a Ca2+-dependent manner by a depolarizing concentration of KCl, raising the possibility of a neuroregulatory role for met5-enkephalin-arg6-phe7. Characterization of the immunoreactive material by gel filtration and high pressure liquid chromatography revealed the presence of multiple forms of immunoreactive material in some brain regions.

Animals↗