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Biomedical subjects

Y Yiangou

Publications and source records attributed to Y Yiangou.

At least 37 records · Page 2Linked to original sources
PubMed1990

Development of neuroendocrine tumors in the gastrointestinal tract of transgenic mice. Heterogeneity of hormone expression.

Expression of hormones in endocrine tumors and derived cell lines of transgenic mice carrying insulin-promoted oncogenes has been investigated by histochemical, immunohistochemical, ultrastructural, and radioimmunologic means. Tumors of the pancreas, small intestine, mesentery, and liver were examined. Insulin-immunoreactive cells were prevalent in pancreatic tumors, with a significant subpopulation of pancreatic polypeptide-immunoreactive elements. Conventional ultrastructural and immunogold analysis identified insulin-storing beta granules in pancreatic tumor cells. In contrast, the largest immunoreactive subpopulation of intestinal tumors expressed secretin (53% of total cells), followed by proglucagon-related peptides (15%), glucose-dependent insulinotropic polypeptide (7%), gastrin (7%), pancreatic polypeptide (2%), neurotensin (2%), and somatostatin (1%). No detectable immunoreactivity for either insulin or serotonin was observed. Electron microscopy and immunogold labeling showed that intestinal tumor cells contained secretin-storing S-type granules. Lymph node and liver tumors contained secretin-immunoreactive cells with ultrastructural features similar to those of intestinal tumors. In addition, high levels of circulating insulinlike and secretinlike immunoreactants were detectable. Analogous hormone profiles were identified in tumor cell lines and culture media. Large T-antigen immunoreactivity was detected in all the nuclei of neoplastic cells, as well as in insulin-immunoreactive elements of non-neoplastic islets and pancreatic ducts and in some secretin-immunoreactive cells of small intestinal mucosa. These data indicate that neuroendocrine tumors arise both in beta cell and S-cell subpopulations of transgenic mice.

Animals↗
PubMed1989

Peptide histidine valine-42 stimulates gastric acid secretion in man.

The effect of peptide histidine valine-42 (PHV-42) on gastric acid secretion was studied in man. PHV-42 was infused into 5 healthy volunteers at a dose of 10 pmol/kg/min. This dose caused a significant stimulation of basal gastric acid and potassium output. There were no significant changes in circulating gastrin throughout the infusion. In 2 subjects with a background of submaximal pentagastrin stimulation, PHV-42 infusion at the same dose did not alter acid secretion in either subject. The previous observation that PHV-42 is found particularly in the stomach and the new finding that it stimulates basal gastric secretion suggest the possibility that PHV-42 could have a role in local control of acid secretion.

Adult↗
PubMed1989

Effects of prepro-vasoactive intestinal polypeptide-derived peptides on net fluid flux in small intestine of anesthetized rats.

Intravenous infusion of low doses of vasoactive intestinal polypeptide, peptide histidine valine-42, and peptide histidine methionine (and the rat equivalent, peptide histidine isoleucine) into anesthetized rats caused a reduction in net absorption of fluid from the small intestine. Larger doses caused a net fluid secretion. At the same nominal infusion rates, peptide histidine valine-42 appeared to be the most potent. In terms of plasma concentrations achieved, however, vasoactive intestinal polypeptide was approximately six times more active than the other two human peptides. If confirmed in humans, these results would suggest that peptide histidine methionine and peptide histidine valine may be as important as vasoactive intestinal polypeptide in causing the watery diarrhea seen in the Verner-Morrison syndrome in which plasma levels of all three peptides are raised.

Absorption↗
PubMed1989

Purification and characterisation of cerebellins from human and porcine cerebellum.

The primary human and porcine structure of the novel neuropeptide cerebellin is unknown. These peptides were, therefore, isolated by a combination of ion-exchange and reverse-phase chromatography using a specific radioimmunoassay against rat cerebellin. The sequences of the peptides were deduced by mass spectrometry (for both human and porcine cerebellins) and gas-phase Edman degradation (for porcine cerebellin). In both species, two molecular forms were identified. In the human, the major form corresponded to the pentadecamer [des-Ser1]-cerebellin (approximately 95% of the total) and the minor form, to the hexadecamer peptide. In the pig, however, both molecular forms were present in approximately equal amounts. The finding that the sequences of human and porcine cerebellin are identical to that of the rat suggests that strong evolutionary pressure has acted to conserve this sequence.

Amino Acid Sequence↗
PubMed1988

Isolation and characterisation of GLP-1 7-36 amide from rat intestine. Elevated levels in diabetic rats.

Glucagon-like peptide-1 (GLP-1) was purified to homogeneity by HPLC and anion-exchange chromatography. A molecular mass of 3297.4 Da was obtained by FAB mass spectrometry which corresponded exactly to GLP-1 7-36 NH2, providing evidence that amidation occurs at an arginine residue during the post-translational processing of GLP-1. The distribution of GLP-1 7-36 NH2-like immunoreactivity (GLP-1 7-36 NH2 IR) was determined in the rat gastrointestinal tract. Highest concentrations were found in terminal ileum and colon. Streptozocin-induced diabetic rats, who showed a significant increase in food intake, had a significant increase of GLP-1 7-36 NH2 IR in the colon.

Animals↗
PubMed1988

Peptide histidine methionine (PHM) increases ileostomy output.

The human vasoactive intestinal peptide (VIP) gene also encodes peptides histidine methionine (PHM) which has substantial sequence homology with VIP. Both are present in nerve fibers in the human ileum and circulate in greatly increased concentrations in patients with the watery diarrhoea syndrome. We have infused PHM (23 pmol/kg/min) into 5 patients with ileostomies to determine the effect of PHM on human ileal output. Plasma PHM levels rose from 22 +/- 6 to 6013 +/- 874 pM (mean +/- S.E.M.) during PHM infusions and ileal output rose from 16 +/- 3 to 177 +/- 27 g/30 min (P less than 0.0001). PHM infusions also produced a significant fall in the percentage of solid material and a rise in the concentration of chloride in the ileal effluent. Mean plasma PHM concentrations during PHM infusions were equal to the highest levels seen in patients with the watery diarrhoea syndrome, so PHM may contribute to diarrhoea in this condition. Neuronal PHM may exert physiological control over ileal transport of water and electrolytes.

Chlorides↗
PubMed1988

Effect of peptide histidine valine on cardiovascular and respiratory function in normal subjects.

Non-adrenergic inhibitory nerves may have an important role in regulating airway calibre. A recently discovered peptide, peptide histidine valine, is a potent relaxer of airway smooth muscle in vitro and has been proposed as a possible neurotransmitter in this tissue. The cardiovascular and respiratory effects of graded infusions of this peptide (2.5-10 pmol kg-1 min-1) have been examined in six normal subjects in a placebo controlled, randomised double blind study. The mean (SEM) peak plasma concentration of peptide histidine valine during the highest infusion rate was 2392 (170) pmol/l, representing a 29 fold increase above the basal concentration. This was accompanied by flushing, a significant increase in heart rate of 28 (3.7) beats/min and skin temperature of 1.8 degrees (0.16 degrees) C, but no effect on systolic or diastolic blood pressure. Despite these high plasma concentrations of the peptide and the substantial tachycardia and increase in skin blood flow, there was no change in partial expiratory flow at 40% of vital capacity (Vp40) or in the airway response to inhaled histamine (geometric PD40 9.37 and 9.73 mumol during saline and peptide histidine valine infusion respectively). Although these findings provide no support for a physiological role of peptide histidine valine in controlling airway function in healthy subjects, important effects of locally released peptides in the vasoactive intestinal peptide family cannot be excluded.

Adult↗
PubMed1988

Infusion of prepro-VIP derived peptides in man: effect on secretion of prolactin.

Infusion of the three human prepro-VIP derived peptides [vasoactive intestinal peptide (VIP), peptide histidine methionine (PHM) and the newly discovered peptide histidine valine (PHV-42)] at a constant nominal rate of 5 pmol/kg/min in 6 healthy volunteers for 60 min resulted in plateau plasma levels of 56,475 and 1,052 pmol/l, respectively. Although these values were above those found in the circulation under physiological conditions, only VIP caused a significant rise of prolactin (PRL) during, and postinfusion. Circulating luteinizing hormone and cortisol concentrations remained unchanged. As peptide histidine isoleucine, the porcine equivalent of PHM, has been postulated to be a potent hypophyseal portal pituitary PRL-releasing factor in the rat, we suggest that in man, VIP is more active than either PHM or PHV-42, and is likely to be a better candidate.

Adult↗
PubMed1987

Isolation, characterization, and pharmacological actions of peptide histidine valine 42, a novel prepro-vasoactive intestinal peptide-derived peptide.

The primary structure and biological activity of a novel prepro-vasoactive intestinal peptide (prepro-VIP)-derived peptide has been determined from an adrenal pheochromocytoma. The peptide was purified sufficiently for characterization by fast atom bombardment mapping after cation-exchange and reverse-phase fast protein liquid chromatography. The sequence of this novel peptide corresponds exactly to prepro-VIP-81-122 and has been designated peptide histidine valine 42 (PHV-42). Synthetic PHV-42 reduced both the force and frequency of spontaneous contractions of isolated rat uterus and was at least 12 times more potent than peptide histidine methionine (prepro-VIP-81-107), and over a hundred times more potent than noradrenaline. PHV-42 was also more potent than peptide histidine methionine in relaxing smooth muscle preparations of rat stomach and guinea pig trachea, but was approximately 4-fold less potent in reducing blood pressure than VIP. PHV-42 thus forms a separate subsystem in the VIP family of peptides and may be the most biologically active product of prepro-VIP in certain tissues such as the uterus and trachea.

Adrenal Gland Neoplasms↗
PubMed1987

Peptide histidine-methionine immunoreactivity in plasma and tissue from patients with vasoactive intestinal peptide-secreting tumors and watery diarrhea syndrome.

The presence of peptide histidine-methionine (PHM)-like peptides has been determined in plasma and tumor specimens from patients with vasoactive intestinal peptide (VIP)-secreting tumors and the watery diarrhea syndrome. All patients had strikingly elevated plasma concentrations of PHM immunoreactivity (median, 1800; range, 500-6800 pmol/liter; n = 12), which were higher than those of VIP (median, 235; range, 50-580 pmol/liter). In patients with other endocrine and nonendocrine pancreatic tumors, plasma PHM concentrations were not significantly different from normal (median, 20; range, 5-60 pmol/liter; n = 28). Plasma samples from patients with diarrhea due to other illnesses also had PHM concentrations that were not significantly different from normal (median, 40; range, 10-80 pmol/liter; n = 23). The gel chromatographic profiles of plasma and tumor extracts from patients with VIP-secreting tumors revealed the presence of at least two molecular forms that reacted with an antiserum directed to the N-terminus of PHM (SY1). The later peak (Kav, 0.50-0.53) corresponded in position to synthetic PHM and also reacted with the PHM-specific antiserum (SY2). The earlier peak (Kav, 0.30-0.37), not reactive with antiserum SY2, corresponded to a large molecular form of PHM-like immunoreactivity previously identified as the predominant form in normal human stomach and plasma, though not in the rest of the intestinal tract. The neuroendocrine nature of the tumors was confirmed by the demonstration of immunostaining with a battery of antisera to neuroendocrine markers. Immunocytochemistry revealed the presence of both VIP and PHM in tumor cells. The presence of high circulating concentrations of PHM-like immunoreactivity in patients with VIP-secreting tumors, as measured with a PHM N-terminus-directed antiserum, SY1, suggests that use of this type of antiserum may provide valuable information in the diagnosis of such tumors. The contribution of the PHM-like peptides to the features of this syndrome is not known.

Adenoma, Islet Cell↗
PubMed1986

Characterization of a novel prepro VIP derived peptide.

A newly identified, large molecular weight form of peptide histidine methionine (PHM), has been found not only where it was first revealed, in the stomach, but also in high concentrations in the nasal mucosa and urogenital system, though not in the central nervous system, intestine and lung. An antibody to the spacer peptide sequence prepro-VIP 111-122, lying between PHM and VIP, also reacts directly with the large molecular form of PHM. It is suggested that the post-translational processing of prepro-VIP differs between tissues and in some, cleavage may not occur at the C-terminal end of PHM. The biological significance of this is currently unclear.

Amino Acid Sequence↗
PubMed1986

A VIP/PHI-containing pathway links urinary bladder and sacral spinal cord.

Nerve fibres containing VIP and the co-produced PHI are found in the dorsal horn and autonomic centres of the sacral spinal cord and in pelvic organs. We have investigated the origin of these nerve fibres and a possible peptide-containing pathway linking pelvic viscera with the spinal cord of the cat and rat using neurochemical and neurosurgical procedures, retrograde tracing and immunocytochemistry. Cell bodies were located in the dorsal root ganglia (after colchicine injection), pelvic ganglia and bladder wall. Capsaicin treatment induced a loss of VIP/PHI from the dorsal horn. Retrograde tracing from the bladder revealed True Blue labelled cells in the dorsal root ganglia (L6, S1), parasympathetic nuclei and pelvic ganglia. Labelled cells were sequentially immunostained for VIP/PHI which were numerous in pelvic ganglia and scattered and weak in dorsal root ganglia. Pelvic nerve section induced a decrease of VIP/PHI immunoreactivity from the spinal cord and no change or a minimal increase in immunoreactive nerve fibers of the bladder. Thus pelvic visceral afferents with cell bodies in the dorsal root ganglia are a significant source of VIP/PHI-containing fibres in the sacral dorsal horn.

Afferent Pathways↗
PubMed1985

Molecular forms of peptide histidine isoleucine-like immunoreactivity in the gastrointestinal tract. Nonequimolar levels of peptide histidine isoleucine and vasoactive intestinal peptide in the stomach explained by the presence of a big peptide histidine isoleucine-like molecule.

Regional specific antibodies and chromatography were used to analyze the distributions and molecular forms of peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP) in the porcine intestine. Both peptides were present along the entire length of the intestine, the highest concentrations occurring in the colon. Concentrations of PHI immunoreactivity, measured with three different antisera, and VIP immunoreactivity were approximately equal in all parts of the gastrointestinal tract except in the stomach. In the stomach, the concentration of PHI immunoreactivity, measured with the N-terminally directed antibody R8403, although equal to the corresponding VIP concentration, was two to four times higher than the PHI immunoreactivity detected with the two C-terminally directed PHI antisera T33 and T41. Chromatographic analysis on Sephadex G-50 superfine of gastric extracts revealed only one VIP immunoreactive peak that eluted in the same position as the porcine VIP standard, at Kav 0.53. A PHI immunoreactive peak was also detected with the C-terminally directed PHI antisera in the same position as porcine PHI standard. However, with the N-terminally directed PHI antiserum R8403, an additional PHI immunoreactive peak was detected in gastric extracts constituting the predominant form present, and this peak eluted earlier at Kav 0.37. The PHI immunoreactive material that eluted earlier was present in the rest of the intestine in only small amounts. As VIP and PHI are believed to be derived from a common precursor, it is suggested that in the stomach the posttranslational enzymic processing of the precursor is different from that in the other parts of the intestine.

Animals↗
PubMed1985

Peptide histidine methionine (PHM) and the human male genitalia.

Peptide histidine methionine-like immunoreactivity (PHM-IR) has been demonstrated to be present in the human penis both by radioimmunoassay and immunohistochemistry with particularly high levels in the corpus cavernosum and vas deferens. In the cavernosa, PHM-IR has been localised entirely, in nerves around arteries. High performance liquid chromatography indicated that this PHM-IR co-eluted with synthetic PHM but not porcine PHI. The presence of PHM-IR in the penis suggests that this neuropeptide may play a functional role in penile function.

Fluorescent Antibody Technique↗
PubMed1984

PHI-like immunoreactivity in the gallbladder and in vitro effect of porcine PHI on smooth muscle of the gallbladder.

The occurrence and distribution of PHI-like immunoreactivity in the guinea pig gallbladder has been analysed by radioimmunoassay and immunocytochemistry. Chromatography of gallbladder extracts by gel permeation and high-performance liquid chromatography revealed that guinea pig PHI-like immunoreactivity is of a similar size to that of porcine PHI but may differ in its amino acid sequence. Immunocytochemistry showed PHI-immunoreactivity to be localised to nerves found predominantly in the ganglionated plexus and the mucosal plexus of the gallbladder. Pure natural porcine PHI induced a dose-dependent relaxation of the isolated guinea pig gallbladder muscle which was not blocked by antagonists to acetylcholine, catecholamines, histamine, and 5-hydroxytryptamine. PHI may thus be one of the local factors involved in controlling gallbladder function.

Animals↗
PubMed1984

Comparative distribution of vasoactive intestinal polypeptide (VIP), substance P and PHI in the enteric sphincters of the cat.

In the feline gastrointestinal tract, the neuropeptides, substance P, VIP and PHI were investigated by specific radioimmunoassays and immunocytochemistry. The concentrations of all 3 peptides and the level of peptidergic innervation were significantly less in the anal sphincter than elsewhere, whereas no significant differences were seen between other sphincter and non-sphincter regions.

Anal Canal↗