Search PubMed⌕ Search

Biomedical subjects

Y Yiangou

Publications and source records attributed to Y Yiangou.

49 records · Page 3Linked to original sources
PubMed1984

PHI-like immunoreactivity co-locates with the VIP-containing system in human lumbosacral spinal cord.

Using a specific radioimmunoassay and immunocytochemistry, the quantitative regional distribution and localization of PHI-like immunoreactivity was studied in normal postmortem human spinal cord. The levels of PHI-like immunoreactivity were low in the cervical and thoracic region whereas the lumbar and especially sacral regions showed higher levels, with dorsal sacral concentrations exceeding ventral concentrations. Chromatographic analysis by high pressure liquid chromatography revealed that the PHI-like immunoreactivity in human spinal cord elutes slightly earlier than pure porcine PHI, and may correspond to PHM-27, a PHI-27-like peptide found in human preprovasoactive intestinal polypeptide. Immunocytochemical studies show a distinctive distribution of PHI-like immunoreactive fibres and terminals at the lumbosacral segments. The distribution of PHI-like immunoreactivity is thus similar to that of VIP, and unlike a number of other neuropeptides; with VIP, it may mark a system which has a role in the spinal control of urogenital function in man.

Aged↗
PubMed1984

Characterization of peptide histidine isoleucine-like immunoreactivity in the rat, human, guinea-pig and cat gastrointestinal tracts--evidence of species differences.

Peptide histidine isoleucine-like immunoreactivity (PHI-LI) was measured by radioimmunoassay in various mammalian ileal extracts fractionated by gel filtration and high-performance liquid chromatography (HPLC). The PHI-LI in the cat, human, guinea-pig and rat tissues were of similar molecular size, being indistinguishable from the porcine standard by gel filtration on Sephadex G-50 superfine, but significant differences were noted on HPLC. The major PHI-LI peaks of guinea-pig and rat were less retained than cat and human PHI-LI which had a similar retention time to porcine PHI. Human PHI-LI, although being chromatographically similar to porcine PHI, was immunologically different. This variation in molecular properties of PHI-LI suggests that extrapolation of experimental results of different species should be treated with great caution.

Animals↗
PubMed1984

Distribution of peptide histidine isoleucine in the mammalian respiratory tract and some aspects of its pharmacology.

Peptide histidine isoleucine (PHI), a newly discovered neuropeptide, has been detected by RIA and immunocytochemistry in the upper respiratory tracts of the guinea pig, rat, and cat. HPLC of tracheal extracts showed a single peak of PHI immunoreactivity in each species. The immunoreactive PHI peak found in the guinea pig and rat trachea was eluted earlier than the corresponding peak from the cat, which was coeluted with the porcine PHI standard. Immunocytochemistry showed PHI immunoreactivity to be present within ganglion cells and nerve fibers in the respiratory tracts of all three species. The distribution of PHI was similar to that of vasoactive intestinal polypeptide and ganglion cells were found to contain both PHI and vasoactive intestinal polypeptide immunoreactivities. Pure natural porcine PHI induced a dose-dependent relaxation of isolated guinea pig tracheal muscle which was not blocked by antagonists to catecholamines, histamine, 5-hydroxy-tryptamine, and acetylcholine. PHI may thus be one of the local factors in respiratory control.

Animals↗
PubMed1984

Distribution of immunoreactive growth hormone-releasing hormone in the human brain and intestine and its production by tumors.

A recently developed RIA for human pancreatic tumor GH-releasing hormone (hpGRH1-44NH2) was used to investigate its distribution in the human gastrointestinal tract and brain, and to determine the incidence of its production by tumors. GRH-immunoreactivity (GRH-IR) was present in several regions of the human brain, the highest concentration occurring in the hypothalamus, septum, and substantia inominata. In the gastrointestinal tract GRH-IR was present in the upper intestine, where it was confined to the epithelial mucosa. Approximately one third of all tumors examined (35 out of 97) contained significant amounts of GRH-IR. Gel chromatography of brain and intestinal extracts, and of several tumors, revealed the presence of two molecular forms of GRH-IR, one coeluting with the synthetic hpGRH1-44 amide standard (and also hpGRH1-40) and another eluting significantly later. The earlier eluting GRH-IR peak was found to be similar to the synthetic hpGRH1-44 NH2 and hpGRH1-40 on high pressure liquid chromatography analysis.

Adult↗
PubMed1983

Ontogeny of PHI in the rat brain.

The regional distribution of immunoreactive PHI (IR-PHI) was investigated in rat brain between postcoitum (pc) and day 60 postpartum (pp). IR-PHI was undetectable in all regions of the foetal brain, and only very small amounts were found at day 7 pp. However, there was a dramatic increase thereafter reaching a peak at day 20 pp (e.g. in the hippocampus there was a 12-fold increase in the PHI concentration). Highest concentrations were found in the cortex (40 +/- 5 pmol/g) and hippocampus (35 +/- 8 pmol/g), with lower concentrations in the diencephalon (11 +/- 4 pmol/g) and mesencephalon (10 +/- 3 pmol/g). The brainstem and cerebellum contained very low amounts of IR-PHI. Permeation analysis of brain extracts, on Sephadex G50-superfine, indicated the presence of one major form of IR-PHI which eluted in a similar position to pure intestinal porcine PHI and human intestinal PHI.

Animals↗
PubMed1983

The presence of peptide histidine-isoleucine in human, dog, guinea-pig and rat pancreas.

Peptide histidine isoleucine-like immunoreactivity has been detected in the pancreas of man (10.3 +/- 2.6 pmol/g), dog (6.5 +/- 1.1 pmol/g), guinea-pig (5.8 +/- 0.9 pmol/g) and rat (0.7 +/- 0.1 pmol/g) using a specific radioimmunoassay. Chromatographic analysis of the pancreatic extracts by high performance liquid chromatography indicated that both guinea-pig and rat have a molecular form of the immunoreactivity which is distinct from the porcine intestinal peptide histidine-isoleucine.

Animals↗
PubMed1983

Radioimmunoassay and intramural distribution of PHI-IR in human intestine.

The objective of this study was to develop a radioimmunoassay for PHI and use this to assess its intramural distribution in the human intestine. The antibody was harvested following immunization with porcine PHI conjugated to bovine serum albumin by glutaraldehyde, and the iodinated PHI tracer was prepared by the Iodo-gen method. The assay system showed no cross-reaction with other members of the glucagon-secretin family of peptides and was sensitive to changes of PHI of 2 fmol/tube (95% confidence). High concentrations of immunoreactive PHI were found in the human intestine, exclusively localized in the nonendocrine gut layers, suggesting a possible neuroendocrinological or neurotransmitter role for PHI.

Chromatography↗
PubMed1983

Peptide histidine isoleucine (PHI). A secretagogue in porcine intestine.

PHI (peptide histidine isoleucine) is a recently identified porcine peptide, present in large quantities in the intestine, which has sequence homologies with VIP, an established intestinal secretagogue, and with secretin, glucagon, and GIP. The effects of PHI on jejunal, ileal, and colonic fluid and electrolyte transport were studied in the pig. PHI appears to be an intestinal secretagogue inducing a reversible net secretion of fluid and electrolytes in jejunum and ileum and less marked effects in the colon.

Animals↗
PubMed1982

PHI stimulates intestinal fluid secretion.

Regulatory peptides are likely to have a role in the control of net intestinal fluid transport. PHI is a peptide recently isolated from porcine duodenum which has been shown to have sequence homologies with other peptides of the glucagon-secretin family. We have studied the effect of intravenous infusion of synthetic PHI on net intestinal fluid transport in the rat small intestine. During PHI infection net absorption was reduced in the duodenum and jejunum and net secretion was observed in the ileum. Thus synthetic PHI appears to be capable of strongly stimulating intestinal secretion in the rat.

Animals↗
PubMedDate not supplied

Effects of prepro-vasoactive intestinal peptide-derived peptides on the murine immune response.

We have studied the effects of prepro-vasoactive intestinal polypeptide-derived peptides on lectin-induced lymphocyte proliferation and natural killer cell (NK) activity in cells from murine spleen, mesenteric lymph nodes, Peyer's patches, thymus and peripheral blood mononuclear lymphocytes (PBL). These peptides (vasoactive intestinal peptide (VIP), peptide histidine methionine (PHM-27) and peptide histidine valine (PHV-42)) showed differential effects in their immune response in a dose- and tissue-dependent manner. All peptides significantly decreased DNA synthesis in spleen (range: 45-30%), lymph nodes (range: 30-0%), Peyer's patches (range: 30-4%) and PBL (range: 30-16%). In these tissues there was no significant difference in their potency. In the thymus, however, PHM-27 (range: 27-15%) was significantly more potent (p less than 0.001) in inhibiting DNA synthesis than either VIP (range: 6-0%) or PHV-42 (range: 20-8%). The modulatory effects on NK activity by these peptides also showed an inhibitory effect. The order of potency was: VIP (range: 40-27%), PHV-42 (range: 22-11%) and PHM-27 (range: 20-8%). The presence of VIP inhibitor [( D-p-chloro-Phe6,Leu17]-VIP) at 10(-8) M in both functional assays caused a significant antagonism of the effects of VIP but not PHM-27 or PHV-42. Our results suggest the existence on lymphocytes of different receptors for prepro-VIP-derived peptides, and that they may be considered as important immunoregulatory molecules. Their mechanism of interaction, however, is not clearly understood.

Animals↗
PubMedDate not supplied

The distributions of PHI and VIP in porcine gut and their co-localisation to a proportion of intrinsic ganglion cells.

VIP and PHI share sequence homology and certain biological actions. Immunocytochemistry and radioimmunoassay were used to see if the two peptides also have similar distributions in the gut of the pig. PHI-immunoreactive fibres were found, like those containing VIP, in all layers of the bowel wall but in lesser numbers. Unlike VIP-immunoreactive nerves, however, which are ubiquitous in the gastrointestinal tract, PHI-containing neurons were numerous in all areas except the fundus, where only few fibres and no ganglion cells were found to be reactive to PHI antibodies. PHI and VIP immunoreactive materials were also quantified by specific radioimmunoassay of tissue extracts. The concentrations of PHI and VIP were similar in all regions of the gut, except in the fundus where the quantities of VIP-immunoreactivity far exceeded those of PHI. The presence of both VIP- and PHI-immunoreactivities in ganglion cells of the sub-mucous plexus allowed investigation of the co-localisation of the peptides. Serial sections through ganglion cells revealed that a major proportion contain both PHI- and VIP-immunoreactivity. Some cells contained VIP alone, or VIP and weak, equivocal immunostaining of PHI, and a sub-population contained no peptide-immunoreactivity. The presence of both VIP- and PHI-immunoreactivities in the same ganglion cell supports the recent reports of the isolation and characterisation, using genetic technology, of their common precursor molecule. The finding of VIP and not PHI in the fundic region suggests the differential expression of the two peptides.

Animals↗
PubMedDate not supplied

The regional distribution of NPY-, PHM-, and VIP-containing nerves in the human female genital tract.

The regional distributions of neuropeptide Y (NPY), peptide histidine-methionine (PHM), and vasoactive intestinal polypeptide (VIP) immunoreactivities in the human female genital tract have been estimated by specific radioimmunoassays, and their molecular forms determined by chromatography. The localisation and distribution of these three peptides was carried out by immunocytochemistry. The vagina and cervix contain high concentrations of NPY- and VIP-immunoreactive nerves, mainly localised around the vascular and nonvascular smooth muscle. VIP-containing nerves were, in addition, seen beneath the cervical and, in particular, the vaginal epithelium. A comparatively high level of immunoreactive NPY is found in the fallopian tube, mainly around the circular muscle coat. There is evidence that VIP is a neurotransmitter in the female genital tract, and these results suggest a similar role for NPY and PHM.

Adult↗