Search PubMed⌕ Search

Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 577 records · Page 32Linked to original sources
PubMed1992

Identification of an abundant monkey epididymal transcript encoding a homologue of human CAMPATH-1 antigen precursor.

A number of cDNA clones encoding a small (0.5-0.6 kb) transcript have been isolated from a monkey (Macaca fascicularis) epididymal cDNA library. DNA sequence analysis indicates that this abundant epididymal transcript is homologous to the human CAMPATH-1 (CDw52) antigen precursor, a GPI-anchored membrane glycoprotein previously described on lymphocytes and monocytes.

Amino Acid Sequence↗
PubMed1992

Crystal and molecular structure of a DNA fragment containing a 2-aminoadenine modification: the relationship between conformation, packing, and hydration in Z-DNA hexamers.

The crystal and molecular structure of d(CGUA'CG)2 (where A' is 2-aminoadenine) has been determined and refined to an R factor of 13.8% for data 8.0-1.3 A. The structure is very similar to the original Z-DNA structures with the sequence d(CGCGCG)2 [Gessner, R. V., Frederick, C. A., Quigley, G. J., Rich, A., & Wang, A. H.-J. (1989) J. Biol. Chem. 264, 7921] and shows that the substitution of 2-aminoadenine-uracil base pairs in the two central steps is consistent with Z-DNA formation. In addition, we show how waters mediating intermolecular interactions may help to explain the ZI-ZII conformational pattern found in many Z-DNA structures.

2-Aminopurine↗
PubMed1992

A mammalian epididymal protein with remarkable sequence similarity to snake venom haemorrhagic peptides.

Following spermatogenesis in the testis, mammalian spermatozoa pass into the epididymis, where they undergo changes which confer on them forward motility and the ability to recognize and penetrate the egg. Many of these maturation events involve androgen-regulated epididymal proteins which become associated with the sperm membrane, and/or effect changes to integral sperm membrane proteins. Here we report the sequence of an 89 kDa androgen-regulated protein from rat (Rattus norvegicus) and monkey (Macaca fascicularis) epididymis that is synthesized exclusively in the caput region and is localized on the apical surface of its principal epithelial cells. This protein shows remarkable similarity to a variety of proteases and disintegrins found in snake venoms and is similar to, but distinct from, the guinea-pig sperm surface PH-30 alpha/beta complex recently implicated in sperm-egg recognition and fusion.

ADAM Proteins↗
PubMed1992

Endothelin regulation of neuropeptide release from nerve endings of the posterior pituitary.

We have investigated the role of endothelin (ET) in the stimulus-secretion coupling mechanism in the posterior pituitary. We report that isolated nerve endings contain immunoreactive endothelin, the level of which is regulated by homeostatic mechanisms involved in control of water balance. ET-1 and ET-3 potentiate vasopressin release induced by depolarization through interaction with specific receptors of the ETA subtype and this response is antagonized by sarafotoxin S6b. The second messenger for this effect, however, remains unknown since the potentiation of depolarization-induced vasopressin release occurs in the absence of an increase in cellular calcium.

Animals↗
PubMed1992

Azimuthal processing in the posterior auditory thalamus of cats.

The responses to free-field acoustic stimuli of 157 units in the auditory thalamus of anesthetized cats were studied in relation to the localization of pure tone stimuli in the azimuthal plane. Units were classified as 'directional' if their firing rates at sound levels in excess of 20 dB above threshold varied by more than 50% as a function of azimuth. Sixty-five % of the units in the nucleus of the brachium of the inferior colliculus and 30% in the ventral division of the medial geniculate body were found to be directional, suggesting different processing channels for sound localization between colliculus and cortex.

Acoustic Stimulation↗
PubMed1992

Genetic evidence for an androgen-regulated epididymal secretory glutathione peroxidase whose transcript does not contain a selenocysteine codon.

Epididymal glutathione peroxidase (GPX) has been suggested as a major factor in combating loss of fertility of spermatozoa due to lipid peroxidation. We report here the isolation and sequence of putative GPX cDNAs from rat (Rattus rattus) and cynomolgus-monkey (Macaca fascicularis) epididymis, which exhibit marked sequence identity with known GPXs. In both species the cDNAs encode predicted preproteins containing 221 amino acid residues. Unlike other characterized GPX sequences, epididymal GPX mRNA does not contain a selenocysteine codon (UGA). However, sequence comparison and molecular-modelling studies suggest a high degree of structural conservation between epididymal and other GPXs. Transcripts corresponding to epididymal GPX are not detected in a variety of other tissues (liver, spleen, kidney and testis) and appear to be androgen-regulated in the epididymis.

Amino Acid Sequence↗
PubMed1992

Metabolism of nitroglycerin by smooth muscle cells. Involvement of glutathione and glutathione S-transferase.

Metabolism of nitroglycerin (GTN) in the vascular smooth muscle is required for the drug to be effective in the treatment of angina pectoris and congestive heart failure. The usefulness of GTN is limited by the development of tolerance to the drug. The metabolism of GTN was studied in its target tissue, vascular smooth muscle. Inorganic nitrite was produced by cultured smooth muscle cells when GTN was added to the culture dish. Nitrite production increased with increasing GTN concentration and with incubation time. The enzymatic nature of GTN metabolism to nitrite was assessed by enzyme inhibition studies. Indocyanine green, a non-substrate inhibitor of glutathione S-transferase, inhibited GTN metabolism by smooth muscle cells. Cellular glutathione is also involved in GTN metabolism by the smooth muscle cell. Pretreatment with phorone, a glutathione S-transferase substrate, depleted cellular glutathione and decreased nitrite production from GTN. Pretreatment with buthionine sulfoximine, inhibitor of gamma-glutamylcysteine synthetase, decreased intracellular glutathione and caused decreased GTN metabolism in smooth muscle cells. Removal of cysteine from the smooth muscle cell incubation medium in combination with buthionine sulfoximine pretreatment decreased GTN metabolism to a lower level than buthionine sulfoximine pretreatment alone. This study shows that glutathione S-transferase and glutathione are involved in GTN metabolism by cultured smooth muscle cells.

Animals↗
PubMed1992

Irritable bowel syndrome in the general population.

OBJECTIVE: To determine the prevalence of symptoms compatible with a clinical diagnosis of irritable bowel syndrome in the general population. DESIGN: Validated postal questionnaire sent to 2280 subjects randomly selected in 10 year age bands from the lists of eight general practitioners. The Manning criteria were used to define irritable bowel syndrome. SETTING: Urban population in Southampton and mixed urban-rural population in Andover, Hampshire. RESULTS: A response of 71% yielded 1620 questionnaires for analysis, of which 412 (25%) reported more than six episodes of abdominal pain in the preceding year, with 350 (22%) reporting symptoms consistent with the diagnosis of irritable bowel syndrome. The male: female ratio was 1:1.38. More subjects with irritable bowel syndrome had constipation and diarrhoea and 35% with the syndrome reported rectal bleeding compared with an overall prevalence of 20%. Other symptoms and conditions including heartburn, dyspepsia, flushing, palpitations, migraine, and urinary symptoms were significantly more common in the group with irritable bowel syndrome. Abdominal pain in childhood was more common in the subjects with irritable bowel syndrome (12%) than without (3%). One third of the group with irritable bowel syndrome had sought medical advice during the study period (male:female ratio 1:1.21); consultation behaviour was influenced by age and the presence of associated symptoms, varied considerably among patients registered with different general practitioners, and was poorly correlated with symptom severity. CONCLUSION: Symptoms consistent with a diagnosis of irritable bowel syndrome are present in almost one quarter of the general population and tend to be associated with a number of other complaints and conditions, some of which may reflect smooth muscle dysfunction.

Adult↗