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Biomedical subjects

J Wharton

Publications and source records attributed to J Wharton.

125 records · Page 7Linked to original sources
PubMed1980

Enkephalin-, VIP- and substance P-like immunoreactivity in the carotid body.

The carotid body type I cell contains amines and has features, both morphological and cytochemical, which indicate that it may also produce a peptide. Many regulatory peptides are now known to be present in both central and peripheral tissues. In the periphery these neuropeptides occur in both classical endocrine (APUD) cells and the neurones of the autonomic nervous system. We have now investigated the possible presence of neuropeptides in the cat carotid body using both immunocytochemistry and radioimmunoassay. Met- and Leu-enkephalin-like material occurred in considerable quantities in carotid body extracts and enkephalin-like immunoreactivity was localised in type I cells. Both vasoactive intestinal polypeptide (VIP)- and substance P-like immunoreactivity was also present but was localised in nerve fibres distributed throughout the organ. These active neuropeptides are widely distributed in mammalian tissues, forming a diffuse regulatory system which now seems to include the carotid body.

Animals↗
PubMed1980

The differential distribution of vasoactive intestinal polypeptide in the normal human female genital tract.

VIP-like immunoreactive material is present in the female reproductive tract, with a distinct pattern of distribution. The highest concentrations of extractable material and immunoreactive nerve fibres were found in the cervix and vagina. In the cervix these fibres were seen below the surface epithelium and around cervical glands as well as in association with blood vessels and smooth muscle bundles. In the vagina the nerve fibres were most abundant in th superficial regions of the lamina propria. Scattered fibres were also present in the rest of the uterus and in the fallopian tubes. Chromatographic evidence indicates that this VIP-like material is of a similar molecular size to that extracted from other organs. Possible roles for VIP in the regulation of myometrial activity and of cervical and vaginal dilation and secretion are proposed.

Adult↗
PubMed1979

Bombesin-like immunoreactivity in the avian gut and its localisation to a distinct cell type.

The distribution of a bombesin-like immunoreactive peptide in the avian gastro-intestinal tract was analysed by combined radioimmunoassay and immunocytochemistry. Radioimmunoassay of tissue extracts showed that the largest quantities of bombesin-like immunoreactivity were present in the proventriculus (64.5 +/- 6.0 pmol/g) with smaller but still considerable amounts in the gizzard (40.0 +/- 6.0 pmol/g). Immunocytochemically the extractable bombesin-like immunoreactivity was localised in numerous endocrine cells. These, in the proventriculus, were found mainly in the deeper layers of the mucosa. Further study of these cells by the semi-thin/thin technique revealed the presence of characteristic secretory granules. The functional name BN is proposed for this cell type.

Animals↗
PubMed1977

Defective platelet lipid peroxidation in myeloproliferative disorders: a possible defect of prostaglandin synthesis.

Platelet lipid peroxidation induced by the sulphydryl blocking reagent n-ethylmaleimide [NEM] was measured by production of malonyldialdehyde [MDA]. Lipid peroxidation was decreased in five of 10 patients with proven myeloproliferative disease. The low levels of lipid peroxidation correlated well with in vitro and in vivo tests of platelet function and the bleeding and bruising problems. The reduction in lipid peroxidation with NEM may be due to one or more of the following: [i] an aged platelet population; [ii] an abnormal cell line; [iii] a reduction of the cyclo-oxygenase enzyme activity in the platelet prostaglandin synthetic pathway; [iv] a reduction of the substrate for platelet prostaglandin synthesis, Arachidonic acid; and [v] an abnormality of phospholipase A activation.

Blood Platelet Disorders↗
PubMed1976

A method for the estimation of acetanilide, paracetamol and phenacetin in plasma and urine using mass fragmentography.

Phenacetin, paracetamol and acetanilide can be determined in a plasma or urine sample by the use of deuterium labelled analogues. These are produced by reaction of hexadeuterioacetic anhydride with the appropriate aromatic amine. The -NHCOCD3 group is stable to hydrogen exchange below pH 8. The internal standard is added to the plasma or urine after enzymatic hydrolysis of the paracetamol conjugates and an ethyl acetate extract at pH 5 is evaporated under nitrogen and the residue derivatized with N,O-bis-(trimethylsilyl)-acetamide. An aliquot of this solution is injected into a g.c.m.s. system, and one ion characteristic of the material under study and the ion from the deuterium analogue (3 mass units greater) are monitored using a voltage switching technique. In the case of phenacetin, for example, ions at 251 and 254 are monitored. Calibration curves relating different weight ratios of the hydrogen and deuterium compounds to their respective signals from the gas chromatography mass spectrometer are used to calculate the amount of a compound in a particular sample. These methods have been developed to study the oxidation of acetanilide to paracetamol and the de-ethylation of phenacetin to paracetamol. Preliminary results from experiments with phenacetin will be discussed.

Acetaminophen↗
PubMedDate not supplied

Simultaneous visualization of neuropeptide and acetylcholinesterase nerve subpopulations in the perivascular plexus.

A simple method combining indirect immunofluorescence and histochemical techniques was developed in order to demonstrate the presence of both neuropeptide immunoreactivity and acetylcholinesterase activity in the same whole-mount preparation. It was found that the two methods can be combined without interfering with one another and may be viewed and photographed simultaneously. The guinea pig basilar artery was chosen as a model tissue. While vasoactive intestinal polypeptide immunoreactivity and acetylcholinesterase activity were found to occur in the same perivascular nerve fibres, tyrosine hydroxylase, neuropeptide tyrosine and calcitonin gene-related peptide immunoreactivity were present in distinct nerve subpopulations. It is possible using this double staining procedure, to analyse the interrelationship of putative cholinergic nerves with other components of the autonomic and sensory nervous system.

Acetylcholinesterase↗
PubMedDate not supplied

Radioimmunoassay of alpha rat atrial natriuretic peptide.

Specific antibodies to alpha 1-28 atrial natriuretic peptide have been raised and used for radioimmunoassay of tissue extracts and for light and electron microscopic immunocytochemistry. The radioimmunoassay has been used to quantitate ANP-immunoreactivity in normal rat heart and hypothalamus and immunocytochemistry to demonstrate its localisation in specific tissue structures. Gel chromatography and high pressure liquid chromatography confirm that the majority of ANP-like immunoreactivity in the atria exists as high molecular weight forms. Rat hypothalamus contains immunoreactive ANP; the concentration per gram of tissue being 2-4 thousand fold less than that of the cardiac atria. The supraoptic region of the hypothalamus did not have a significantly different concentration of ANP-like immunoreactivity from the hypothalamic region as a whole. Immunocytochemical staining with ANP antiserum revealed the cardiac ANP-immunoreactivity to be concentrated around the nuclear poles within the cytoplasm of atrial muscle cells. Electron microscopic study of atrial cells stained with the immunogold technique confirmed the localisation of the ANP immunoreactivity to electron-dense secretory granules. The highest density of regional immunoreactive staining was in the subepicardial area, the lowest in the interatrial septum. The finding that the highest quantities of ANP immunoreactivity occur in areas subjected to the greatest distensional forces supports the hypothesis that atrial stretch is a stimulus to the release of this peptide from cells.

Animals↗
PubMedDate not supplied

Co-localization of neuropeptide tyrosine (NPY) and its C-terminal flanking peptide (C-PON).

Neuropeptide tyrosine (NPY) is one of the most abundant and widespread peptides in the mammalian nervous system. Recent isolation and sequencing of the DNA encoding NPY has predicted the existence of a 97 amino acid precursor peptide. Proteolytic processing of this precursor could yield three separate peptide products, an N-terminal signal peptide, neuropeptide tyrosine and a 30 amino acid C-terminal flanking peptide (C-PON). Here, we present evidence that the predicted C-flanking peptide of NPY is widely distributed in both the central and peripheral nervous systems of several mammalian species including man, and has an identical distribution to NPY. It was also demonstrated, using correlative light microscopic immunostaining on serial sections and double electron microscopic immunocytochemistry, that C-PON and NPY immunoreactivities are co-localized in neuronal cell bodies of the brain cortex, sympathetic ganglion cells, norepinephrine-containing granules of the adrenal medulla and in human pheochromocytoma tumor cells.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Substance P-like immunoreactive nerves in mammalian lung.

Substance P-like immunoreactivity was located in nerves in the lungs of guinea pig, rat, mouse and neonatal pigs. These nerves were regularly observed in association with both airways and blood vessels in all region of the lung. They appeared to be more numerous in the guinea pig than in the other mammals studied and differences in distribution were observed. The finding of substance P-like immunoreactive nerves in the lung suggests the presence of another regulatory system within the mammalian lung.

Animals↗