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S James

Publications and source records attributed to S James.

At least 91 records · Page 5Linked to original sources
PubMed1991

Atrial and brain natriuretic peptides share binding sites on cultured cells from the rat trachea.

We examined the distribution of binding sites for alpha-atrial natriuretic peptide (125I-ANP1-28) and the recently discovered porcine brain natriuretic peptide (125I-pBNP) on immunocytochemically identified cells in dissociated culture preparations of the rat trachea. Specific binding sites for both 125I-ANP1-28 and 125I-pBNP were evenly distributed over distinct subpopulations of smooth muscle myosin-like immunoreactive muscle cells, fibronectin-like immunoreactive fibroblasts and S-100-like immunoreactive glial cells. Neither keratin-like immunoreactive epithelial cells nor protein gene product 9.5-like immunoreactive paratracheal neurones expressed natriuretic peptide binding sites, although autoradiographically labelled glial cells were seen in close association with both neuronal cell bodies and neurites. The binding of each radiolabelled peptide was abolished by the inclusion of either excess (1 microM) unlabelled rat ANP or excess unlabelled porcine BNP, suggesting that ANP and BNP share binding sites in the trachea. Furthermore, the ring-deleted analogue, Des-[Gln18, Ser19, Gly20, Leu21, Gly22]-ANF4-23-NH2, strongly competed for specific 125I-ANP1-28 and 125I-pBNP binding sites in the tracheal culture; this suggests that virtually all binding sites were of the "clearance" (ANP-C or ANF-R2) receptor subtype.

Animals↗
PubMed1991

Variation in chemosensitivity and the control of dietary selection behaviour in the locust.

Investigations into the behavioural and underlying physiological mechanisms of dietary selection are presented for the locust, Locusta migratoria. Locusts were fed for 4, 8 or 12 h on one of four chemically defined artificial diets: diet PC, which was nutritionally complete; diet P, containing no digestible carbohydrate; diet C, containing no protein; and diet O, which lacked both protein and digestible carbohydrate. Following this pretreatment, the locusts were provided with both the P and the C diet in a choice test. Detailed analyses of selection behaviour indicated that diets lacking a nutrient for which the insect was deficient were either rejected before a meal was initiated, or, if feeding commenced, eaten in meals of only short duration, while those containing the appropriate nutrients were accepted more readily and eaten in longer meals. Electrophysiological studies showed that this behaviour was paralleled by nutrient-specific changes in gustatory responsiveness. Locusts pretreated for 4h on C diet had increased gustatory responsiveness to stimulation with an amino acid mix, but not to sucrose, while insects fed on P diet showed increased responsiveness to stimulation with sucrose, but not to the amino acid mix. This result is consistent with earlier experiments in which levels of blood nutrients were shown to modulate taste responsiveness in the locust.

Analysis of Variance↗
PubMed1991

Endothelial modulation and changes in endothelin pressor activity during hypoxia in the rat isolated perfused superior mesenteric arterial bed.

1. The isolated superior mesenteric arterial bed of the rat, perfused with Krebs-Henseleit solution containing 10 microM indomethacin, was used to study the effects of reducing dissolved O2 tension on the pressor responses to endothelin-1, endothelin-3 and sarafotoxin S6b. The modulation of these responses by the endothelium was investigated by removing the intima with the detergent CHAPS and, for endothelin-1, by inhibiting nitric oxide production with N omega-nitro-L-arginine methyl ester (L-NAME). Comparison was made with the effects of lowering O2 tension on the pressor responses to noradrenaline and 5-hydroxytryptamine. 2. Lowering the perfusate O2 tension from 551 +/- 2 mmHg to 14.0 +/- 0.5 mmHg did not change the ED50 for endothelin-1 but its maximal responses (Rmax) were increased by 2.1 and 2.7 fold, respectively, in the presence and absence of endothelium. The Rmax values for endothelin-3 were also greater in hypoxia either in the presence (by 2.3 fold) or absence of the endothelium (by 1.6 times) but those for sarafotoxin S6b were only enhanced significantly by hypoxia in the absence of the intima. hypoxia reduced the potencies of endothelin-3 and sarafotoxin S6b whether or not endothelium was present. 3. Endothelial destruction, whether in hypoxic or oxygenated conditions, increased the Rmax values for endothelin-1 and endothelin-3; at both O2 tensions those for endothelin-3 increased more than those for endothelin-1. The ED50 for endothelin-1 was unchanged by destroying the endothelium but endothelin-3 was less potent in the absence of an endothelium than in its presence. Removal of the endothelium did not change the R.ax for sarafotoxin S6b but increased its potency in both hypoxic and oxygenated tissues. 4. In hypoxia, and in the presence of both the endothelium and 100 microM L-NAME, the Rmax for endothelin-1 was 1.6 times greater than that in hypoxia in the absence of L-NAME. Co-infusion of 100 microM L-arginine, but not of 100 mircoM D-arginine, with 100 microM L-NAME reversed this effect. The presence of L-NAME decreased the potency of endothelin-1. 5. Destroying the endothelium did not affect the Rmax for noradrenaline in either oxygenated conditions or hypoxia. Changing 02 tension when the endothelium was intact had no effect on the Rmax but it was 11% greater in oxygenated, than in hypoxic, endothelium denuded preparations. Endothelial destruction decreased the potency of noradrenaline in hypoxia but increased it in oxygenated tissues. In hypoxia, L-NAME had no effect on the ED50 relative to control preparations with endothelium but the Rmax was 30% greater. 6. 5-Hydroxytryptamine gave very small pressor responses in the presence of endothelium in both oxygenated and hypoxic tissues but the Rmax was 1.7 times greater in hypoxia. L-NAME increased the R,,x by 9.8 times in oxygenated preparations and 6.3 fold in hypoxia. The ED5o values were the same in all conditions. 7. It is concluded that, although hypoxia generally increased the R.. for the endothelin/sarafotoxin peptides, the changes could not be explained by a simple increase in receptor number since hypoxia decreased the potency of endothelin-3 and sarafotoxin S6b. Thus alterations in receptor binding or activation properties, or both, also occurred. The changes associated with hypoxia were not common to all vasoconstrictor agonists since, in the absence of endothelial function, hypoxia did not affect the Rmax values for either noradrenaline or 5-hydroxytryptamine. Also, the pressor responses to the peptides and both the amines can be modulated by the endothelium in hypoxia as well as in oxygenated conditions.

Animals↗
PubMed1991

Obesity Stereotypes Among Physicians, Medical and College Students, Bariatric Surgery Patients and Families.

Cultural indoctrination throughout childhood largely defines adult value systems including stereotypic attitudes towards the obese. It is possible that medical education may alter physicians' earlier stereotypes of obesity. 156 subjects, comprising sex distinct adult groups, morbidly obese persons, their family members and significant others. college undergraduates, medical students, medical and surgical residents, and medical school faculty, were surveyed with a questionnaire. It required that each of 32 bipolar adjectives describing obese persons be answered on a -0 to 9-point scale. The adjectives were selected to provide a sweeping array of attributes used commonly to note differences among people (e.g. intelligent-unintelligent, happy-sad, complex-simple) with low values corresponding to the first, usually more favorable, adjective of each pair. Discriminant analysis identified only 5 of 32 adjective pairs (16%) as useful (p < 0.05) in isolating the respondent groups. Although it reached statistical significance, the magnitudes of these differences were not very substantive with reference to a 9-point scale. We conclude that obesity appears to carry a burdensome degree of societal prejudice, as reflected by negative stereotypes, which is largely unaffected by undergraduate or postgraduate medical education.

Journal Article↗
PubMed1990

Colocalization of peptides and a catecholamine-synthesizing enzyme in intramural neurones of the newborn guinea-pig urinary bladder in culture.

The patterns of colocalization of somatostatin (SOM), neuropeptide Y (NPY) and the catecholamine-synthesizing enzyme, dopamine beta-hydroxylase (DBH), were examined in intramural neurones in dissociated cell culture preparations from the detrusor muscle of the urinary bladder of the newborn guinea-pig using an elution-restaining immunocytochemical technique. Large numbers of the intramural neurones contained NPY-like (70-85% of the total neuronal population) and SOM-like (60-75%) immunoreactivities, in contrast to a small population (1-6%) of neurones containing immunoreactivity to DBH. Some neurones were immunoreactive to NPY (15-20%) and SOM (5-10%) alone, while 55-70% of the total neuronal population showed immunoreactivity to both NPY and SOM. NPY-like immunoreactive neuronal cell bodies that did not contain SOM were predominantly binucleate, whereas neuronal cell bodies immunoreactive to SOM alone were mainly mononucleate. Although not seen in every culture preparation, neuronal cell bodies containing both NPY-like and DBH-like immunoreactivities were also observed (less than 5% of the total neuronal population), and most, if not all, of these neuronal cell bodies were binucleate. SOM-like and DBH-like immunoreactivities were not seen in the same neuronal cell body throughout this study. These results show that intramural bladder neurones can be divided into distinct subpopulations based upon the coexistence of specific peptides and enzymes, and the possibility that they sustain local integrative and modulatory roles in bladder function is discussed.

Animals↗
PubMed1990

Autoradiographic visualization of muscarinic receptors on rat paratracheal neurons in dissociated cell culture.

An autoradiographic method was used to determine the distribution of muscarinic receptors on cells cultured from the trachealis muscle of 12-13-day-old rats. Cells identified in these culture preparations included neurones, fibroblasts, smooth muscle, and glial and epithelial cells. The cultured cells were incubated with the specific, irreversible ligand [3H]propylbenzylylcholine mustard, and the autoradiographs generated showed that most, if not all, of the paratracheal neurones observed in these cultures were specifically labelled. Both the neuronal cell body and associated neurites were evenly labelled over their entire surface. Neither the pattern nor the density of neuronal labelling appeared to be influenced by close association with other cultured cell types. Autoradiographic grains for muscarinic receptors also appeared to be uniformly distributed over smooth muscle cells and epithelial cell groups in culture. In contrast, no specific labelling was associated with cultured fibroblasts, glial cells and other non-neuronal supporting cells. The precise localization of muscarinic receptors on different cell types in culture may prove to be useful knowledge in the design of an effective and specific antimuscarinic bronchodilator.

Animals↗
PubMed1990

Autoradiographic localization of specific atrial natriuretic peptide binding sites on immunocytochemically identified cells in cultures from rat and guinea-pig hearts.

Dissociated cell culture preparations from rat and guinea-pig atria and interatrial septum, and from rat ventricles were studied using a combined autoradiographic and immunocytochemical approach. Alpha-atrial natriuretic peptide (125I-ANP1-128) bindings sites were confined to subpopulations of identified non-neuronal cells in each type of culture preparation, and had distinct patterns of labelling. The density of ANP1-28 binding sites was substantially greater in guinea-pig cultures than in rat cultures and was least in rat ventricular cultures. ANP1-28-labelled subpopulations of S-100-like immunoreactive glial cells were only seen in guinea-pig cultures. Von Willebrand factor (vWF)-like immunoreactive endothelial cells and vWF-negative endothelioid cells expressed ANP1-28 binding sites in both the guinea-pig and rat atrial cultures, but were unlabelled in rat ventricular cultures. In contrast, labelled subpopulations of fibronectin-like immunoreactive fibroblasts were present in all of the three types of culture preparation studied. ANP-like immunoreactive myocytes were present in both atrial and ventricular cultures. These cells did not, however, express ANP1-28 binding sites.

Animals↗
PubMed1990

Visualisation of specific binding sites for atrial natriuretic peptide on non-neuronal cells of cultured rat sympathetic ganglia.

The distribution of atrial natriuretic peptide binding sites on cells in dissociated culture preparations of neonatal rat superior cervical ganglia and in explant cultures of rat thoracic sympathetic chain ganglia has been studied. The autoradiographic visualisation of atrial natriuretic peptide binding sites has been combined with the use of specific immunocytochemical markers for glial cells (antiserum to S-100 protein), fibroblasts (antiserum to fibronectin) and neurones (antiserum to protein gene product 9.5) in order to achieve unambiguous identification of the cell types in culture. Specific binding sites for rat 125I-atrial natriuretic peptide(1-28) were observed over subpopulations of fibronectin-like-immunoreactive fibroblasts and S-100-like-immunoreactive glia in the dissociated superior cervical ganglion cultures. However, only a subpopulation of fibronectin-like-immunoreactive fibroblasts possessed atrial natriuretic peptide binding sites in the explant culture preparations. No atrial natriuretic peptide-like-immunoreactive cells were present in either culture. The distribution of autoradiographic grains over individual cell surfaces in culture was uniform, but there were distinct differences in the density of labelling of single cells of the same type. This apparent variation in the number of binding sites on glial cells and fibroblasts in culture did not seem to be related to the morphology of the cells or the surrounding cell types. No sympathetic neurones were labelled with autoradiographic grains in either the dissociated or explant culture preparations. However, the presence of atrial natriuretic peptide binding sites on non-neuronal cells of sympathetic ganglia in culture may be linked to the relationship between atrial natriuretic peptide and the sympathetic nervous system.

Animals↗
PubMed1990

Localization of a locus for Charcot-Marie-Tooth neuropathy type Ia (CMT1A) to chromosome 17.

Phenotypic data for 71 genetic markers for members of five Caucasian kindreds were tested for linkage with the autosomal dominant mutations causing Charcot-Marie-Tooth (hereditary motor sensory) neuropathy type I, characterized by markedly reduced nerve conduction velocities. Lod score analysis gave no evidence of linkage to the closely linked chromosome 1 loci SPTA1-FY-F5-AT3 and APOA2. In contrast, these mutations were found to map closely (zeta = 10.828, theta = 0.0) to D17S58, an anonymous segment of DNA from 17p11.2-p11.1, and thus define the CMT1A locus. Segregation information data for an inferred recombinant offspring indicated that the CMT1A locus is probably proximal to MYH2, the locus encoding adult skeletal muscle myosin heavy polypeptide 2, which maps to 17p13. Analysis of the lod scores on a per kindred basis gave no evidence of genetic heterogeneity.

Charcot-Marie-Tooth Disease↗
PubMed1990

Anxiety and unrealistic optimism.

Substantial evidence suggest that people tend to be unrealistically optimistic that positive events will happen to them and that negative events will not. However, recent research indicates that under certain conditions they may be unrealistically pessimistic. Variations in the levels of optimism and pessimism experienced towards events are generally given cognitive explanations. A relation between optimism and pessimism and anxiety, a variable related to emotion as well as cognition, was investigated in the present study. An inverse correlation was found between how anxious female students in England felt about certain negative events and how unrealistically optimistic they were about the occurrence of those events. It was concluded that the degree of anxiety experienced toward a negative event may affect the level of unrealistic optimism or pessimism toward it.

Adaptation, Psychological↗
PubMed1990

Both A1 and A2a purine receptors regulate striatal acetylcholine release.

The receptors responsible for the adenosine-mediated control of acetylcholine release from immunoaffinity-purified rat striatal cholinergic nerve terminals have been characterized. The relative affinities of three analogues for the inhibitory receptor were (R)-phenylisopropyladenosine greater than cyclohexyladenosine greater than N-ethylcarboxamidoadenosine (NECA), with binding being dependent of the presence of Mg2+ and inhibited by 5'-guanylylimidodiphosphate [Gpp(NH)p] and adenosine receptor antagonists. Adenosine A1 receptor agonists inhibited forskolin-stimulated cholinergic adenylate cyclase activity, with an IC50 of 0.5 nM for (R)-phenylisopropyladenosine and 500 nM for (S)-phenylisopropyladenosine. A1 agonists inhibited acetylcholine release at concentrations approximately 10% of those required to inhibit the cholinergic adenylate cyclase. High concentrations (1 microM) of adenosine A1 agonists were less effective in inhibiting both adenylate cyclase and acetylcholine release, due to the presence of a lower affinity stimulatory A2 receptor. Blockade of the A1 receptor with 8-cyclopentyl-1,3-dipropylxanthine revealed a half-maximal stimulation by NECA of the adenylate cyclase at 10 nM, and of acetylcholine release at approximately 100 nM. NECA-stimulated adenylate cyclase activity copurified with choline acetyltransferase in the preparation of the cholinergic nerve terminals, suggesting that the striatal A2 receptor is localized to cholinergic neurones. The possible role of feedback inhibitory and stimulatory receptors on cholinergic nerve terminals is discussed.

Acetylcholine↗
PubMed1990

Sodium-23 nuclear magnetic resonance imaging of the rabbit kidney in vivo.

The mechanism by which the mammalian kidney generates a concentration gradient of sodium from cortex to papilla is still not entirely understood. Studies of how the kidney as an organ generates this gradient have been hampered by the lack of a noninvasive method for monitoring the intrarenal sodium distribution. Herein, we demonstrate the value of sodium-23 nuclear magnetic resonance (23Na-NMR) imaging to nondestructively assess the intrarenal sodium distribution. 23Na-NMR images were obtained from a surgically exposed kidney preparation that showed the two-dimensional distribution of sodium in the rabbit kidney. In the antidiuretic kidney this gradient resulted in papillary sodium concentrations that were approximately threefold higher than cortical values. Serial 23Na-NMR images obtained during saline infusion demonstrated the kinetics by which the sodium gradient increases with diuresis. The half-time for 23Na washout of the medulla of the kidney was approximately 6 min with this protocol. In addition, a three-dimensional data set of the sodium distribution of the kidney was obtained with voxel dimensions of 1.5 mm3 by use of a three-dimensional 23Na-NMR imaging technique. Without surgical exposure, 23Na-NMR images of the rabbit kidney were collected under completely noninvasive conditions by use of a surface coil. The 23Na-NMR signal from the kidney was easily detected; however, to obtain images of comparable signal-to-noise ratio to the surgically exposed kidney, spatial and temporal resolution were significantly reduced.

Animals↗
PubMed1990

Membranoproliferative glomerulonephritis in a fifteen-month-old boy.

A 15-month-old boy presented with hypertension, edema, heavy proteinuria, gross hematuria and renal insufficiency. A renal biopsy was consistent with classical membranoproliferative glomerulonephritis type I. Although usually thought of as a disease in older children and young adults, membranoproliferative glomerulonephritis can occur as early as the second year of life.

Basement Membrane↗