PubMed Health⌕ Search

Biomedical subjects

W H Taylor

Publications and source records attributed to W H Taylor.

At least 73 records · Page 4Linked to original sources
PubMed1979

Action of human pepsins 1,2,3 and 5 on the oxidized B-chain of insulin.

Human pepsins 1 and 2 attack the B-chain of oxidized insulin at pH 1.7 at the same bonds as does human pepsin 3. At pH 3.5, pepsins 1 and 2 attack insulin B-chain at essentially the same bonds as at pH 1.7, but more slowly. For all three enzymes, the first bond to be hydrolysed is Phe(25)-Tyr(26), followed simultaneously by Glu(13)-Ala(14), Leu(15)-Tyr(16) and Tyr(16)-Leu(17). Human pepsin 5, however, attacks Phe(24)-Phe(25) first of all, followed by Leu(15)-Tyr(16) and Tyr(16)-Leu(17). The results suggest that each pepsin has only one active site. Acid hydrolysis indicates that the sites of enzymic cleavage are not bonds with an inherent instability at low pH.

Amino Acid Sequence↗
PubMed1979

Cigarette smoking, chronic peptic ulceration, and pepsin 1 secretion.

The relationship between the secretion of pepsin 1 (the most electronegative of the pepsins), and the smoking habits of 219 patients has been investigated. Significantly more cigarette smokers with peptic ulceration (72.5%) secreted pepsin 1 in greater than trace amounts after pentagastrin or histamine than did non-smokers with ulceration (51.2%). Differences of a similar order were found for men with duodenal ulcer, women with duodenal ulcer, and all patients with gastric ulcer, but the difference was statistically significant only for men with duodenal ulcer. Significantly more patients with peptic ulcer smoking six to 15 cigarettes/day secreted moderate or high concentrations of pepsin 1 than did heavier smokers or non-smokers. There was no significant association between cigarette smoking and pepsin 1 secretion among 74 patients without ulceration. Maximal acid output was not significantly related to smoking in any group studied. The findings add to the increasing body of evidence linking pepsins and pepsin 1 with the pathogenesis of peptic ulceration.

Adult↗
PubMed1979

Pepsin 5 in gastric juice: determination and relationship to the alkali-stable peptic activity.

Pure human pepsins 1 and 3 are inactivated by incubation at pH 7.1-7.3 for 30 minutes, losing 90% or more of activity. Pepsin 5 is alkali-stable, retaining 100% of activity. Mixtures of pure pepsins 1 and/or 3 with pepsin 5 were found to have greater alkali-stable activity than predicted. Two published methods for determining the alkali-stable fraction of the peptic activity of gastric juice gave, respectively, in our hands values of 45.4-80.0% and 27.5-43.9% of the total activity. These values seemed too high to be attributable only to pepsin 5 in gastric juice, as agar gel electrophoresis shows pepsin 3 to have the principal activity. Electrophoretograms of alkaline incubated gastric juice revealed that large amounts of pepsin 3 retained activity as well as pepsin 5, and a proteolytic zone "4" appeared between them. Alkali inactivation thus does not allow the estimation of pepsin 5 individually in gastric juice. Pepstatin, at a final concentration of 100 to 170 pmol/ml, may be used to estimate pepsin 5 in gastric juice and gave values of 18.0 to 27.6% of the total peptic activity. Pepsin 5, in gastric juice and in mixtures of pepsins, appears to protect pepsin 3 from alkaline-inactivation, and to a lesser extent from pepstatin inhibition.

Alkalies↗
PubMed1979

Hereditary aspects of duodenal ulceration: pepsin 1 secretion in relation to ABO blood groups and ABH secretor status.

Pepsin 1, the ulcer-associated pepsin, occurred significantly more frequently in the gastric juice of those patients with duodenal ulcer who did not secrete A, B, or H antigens into gastric juice than in those secreting these antigens. This observation may explain the increased proportion of such non-secretors among patients with duodenal ulceration. In patients with gastric ulcer and non-ulcer dyspepsia, and in a miscellaneous group of patients, there was no association of pepsin 1 secretion with secretor status, suggesting that the association noted in duodenal ulceration is an indirect rather than a direct one. No increase of pepsin 1 occurred in group O patients with peptic ulcer, so that the increased proportion of such patients in peptic ulcer does not arise from differences in pepsin 1 secretion.

ABO Blood-Group System↗
PubMed1979

An improved radioenzymatic assay for histamine in human plasma, whole blood, urine, and gastric juice.

A radioenzymatic method suitable for the assay of histamine in human blood, urine, plasma, and gastric juice is described. It differs from earlier methods by use of a histamine methyltransferase preparation from pig brain, of high activity tritiated S-adenosylmethionine, and of a heat precipitation step to reduce the previously noted interference from plasma constituents. The method is simpler than those requiring solvent extraction and concentration of histamine, gives recoveries in the range 80-120%, and so sliminates the need for internal standardisation. The method is sensitive and precise with coefficients of variation for blood, urine, and plasma of 5%, 6%, and 13% respectively. The mean +/- standard deviation for normal human plasma histamine is 5 +/- 4 nmol/l, for whole blood 559 +/- 193 nmol/l, and for urine 229 +/- 128 nmol/24h.

Animals↗
PubMed1978

Ovalbumin digestion by human pepsins 1, 3 and 5.

1. Of the three major human pepsins, pepsin 1 has greater proteolytic activity towards ovalbumin than has pepsin 3. Pepsin 5 has low activity towards this substrate. 2. Proteolytic pH-activity curves show only on pH maximum, about pH 1.4 for pepsin 1, pH 1.4--1.5 for pepsin 3 and pH 1.2--1.4 for pepsin 5. The curve for pepsin 3 has a shoulder between pH 2.4 and 3.4. 3. The rate of digestion of ovalbumin by pepsin 1 is approximately three times slower than are those of bovine haemoglobin or human globin. 4. The results suggest that there may be a physiological advantage in having more than one pepsin.

Electrophoresis, Agar Gel↗
PubMed1978

The preparation and purification of individual human pepsins by using diethylaminoethyl-cellulose.

A procedure was devised for isolating human pepsins 1, 2, 3 and 5 from gastric juice by repetitive column chromatography on DEAE-cellulose. The combined yields in four different experiments varied from 14% to 90% of the total peptic activity of the starting material. The isolated individual pepsins were shown to behave as single homogeneous proteins on agar-gel electrophoresis at pH 5.0 and on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. There is preliminary evidence, requiring further study, of two other pepsins, one migrating between pepsins 1 and 2 and the other a pepsin-3 component associating closely with pepsin 5 on chromatography.

Chromatography, DEAE-Cellulose↗
PubMed1978

The isolation and properties of a non-pepsin proteinase from human gastric mucosa.

1. A non-pepsin proteinase, proteinase 2, was successfully isolated free from pepsinogen (by repetitive chromatography on DEAE- and CM-celluloses) from the gastric mucosa of a patient with a duodenal ulcer and the uninvaded mucosa of a patient with a gastric adenocarcinoma. 2. Proteinases 1a and 1b, found in gastric adenocarcinoma, were not found in the gastic mucosa of these patients. 3. Proteinase 2 was shown to have an asymmetrical broad pH-activity curve with a maximum over the pH range 3.0-3.7. 4. Proteolytic activity of proteinase 2 was inhibited by pepstatin; the concentration of pepstatin giving 50% inhibition is of the order of 3nm. 5. Inhibition of proteolytic activity by carbenoxolone and related triterpenoids indicated that at pH 4.0 proteinase 2 possesses structural characteristics relating it to the pepsins and at pH 7.4 to the pepsinogens. 6. The sites of cleavage of the B-chain of oxidized insulin for proteinase 2 at pH 1.7 and pH 3.5 were shown to be similar to those previously established for human pepsin 3 and for the cathepsin E of rabbit bone marrow. 7. The non-pepsin proteinase 2 (cathepsin) of human gastric mucosa has properties more similar to cathepsin E than to the cathepsins D.

Binding Sites↗
PubMed1978

Three-centre study on urinary hydroxyproline excretion in cancer of the breast.

A study instigated by the British Breast Group and involving 3 centres (Edinburgh, Glasgow and Liverpool) was carried out to compare 3 methods for the estimation of urinary hydroxyproline. No significant difference between the first and the second 24 h urine collection was found for each measure of urinary hydroxyproline, within laboratories and within patient groups. Reliable hydroxyproline studies can, therefore, be performed on one 24 h urine collection. The Grant and Ellis/Goldberg methods gave comparable results and the excretion of hydroxyproline in the urine measured by either of these 2 methods could be used to distinguish cases of breast cancer with osseous involvement (as demonstrated by X-rays) from those without. The Hypronosticon Kit method was found to be unreliable as it has 29.4% false negatives in breast-cancer patients with X-ray demonstrable metastases. The incidence of elevated urinary hydroxyproline excretion in breast-cancer patients with negative X-rays was 11/14 (25%), 5/34 (15%) and 8/43 (19%) for the Ellis/Goldberg, Hypronosticon and Grant methods respectively. No conclusion can be drawn regarding the outcome of this group of patients because of the short period of follow-up.

Adult↗
PubMed1978

Effect of cyclo-alkyl lactamimides upon human pepsins and pepsinogens.

1. Eight cyclo-alkyl lactamimides have been investigated for potential inhibitory action upon the pepsins and pepsinogens. 2. Human pepsins 1, 3 and 5 and swine pepsin were inhibited only slightly. 2. Human and swine pepsinogens were inactivated progressively by lactamimides as the number of methylene groups in the nitrogen-containing ring increased. The most potent inactivator studied was N-(cis-2-phenylcyclopentyl)-azacyclotridecan-2-imine hydrochloride. 4. Substitution of benzyl and tertiary butyl groups in the N-containing ring increased the pepsinogen-inactivating property of the cyclo-alkyl lactamimides. 5. N-(cis-2-Phenylcyclopentyl)azacyclotridecan-2-imine hydrochloride may be of potential importance as a therapeutic agent in peptic ulcer, and modifications to the molecule which might increase its pepsinogen-inactivating ability are suggested.

Humans↗
PubMed1978

Effect of calcitonin treatment on osteoclast counts in Paget's disease of bone.

Histological and biochemical changes during calcitonin treatment have been studied in 15 patients with Paget's disease of bone. For each patient, osteoclast counts were made by the same observer on serial needle biopsies of diseased bone from the posterosuperior iliac spine. Serial estimations were also made of the serum alkaline phosphatase and urinary hydroxyproline excretion. A total of 66 biopsies was examined (ranging from two to seven per patient). Osteoclast populations and the biochemical measurements were log normally distributed. During calcitonin treatment there was a statistically significant decrease in: (1) the total osteoclast count per square millimetre; (2) the number per square millimetre of osteoclasts in resorption cavities on the trabecular surface; (3) the relative proportion of osteoclasts sited in resorption cavities compared with total osteoclasts; (4) the serum alkaline phosphatase level; (5) 24-hour urinary hydroxyproline excretion. On stopping treatment there was a statistically significant increase in all of these histological and biochemical values except that the proportion of osteoclasts in resorption cavities remained low. The trabecular cement line pattern remained abnormal during and after treatment in all biopsies examined, and complete suppression of osteoclast activity was not observed. One of the patients developed a Paget's osteosarcoma while on calcitonin therapy.

Aged↗
PubMed1977

Pseudohypoparathyroidism. Variable manifestations within a family.

A wide variety of clinical and biochemical manifestations have been reported in association with pseudohypoparathyroidism and associated disorders. This is illustrated by a family study in which the affected members show widely differing characteristics.

Child, Preschool↗
PubMed1976

Purification of properties of dihydroorotase, a zinc-containing metalloenzyme in Clostridium oroticum.

Dihydroorotase +4,5-L-dihydro-orotate amidohydrolase [EC 3.5.2.3]), which catalyzes the reversible cyclization of N-carbamyl-L-aspartate to L-dihydroorotate, has been purified from orotate-grown Clostridium oroticum. The enzyme is homogeneous when subjected to polyacrylamide gel electrophoresis and is stable at pH 7.6 in 0.3 M NaCl containing 10 muM ZnSO4. The enzyme has a molecular weight of approximately 110,000. Sodium dodecyl sulfate gel electrophoresis, using three different buffer systems, indicated the enzyme is composed of two subunits, each having a molecular weight of 55,000. Dihydroorotase is shown by atomic absorption spectroscopy to be a zinc-containing metalloenzyme with 4 g-atoms of zinc per 110,000 g of protein. The pH optima for the conversion of N-carbamyl-L-aspartate to L-dihydroorotate and for L-dihydroorotate to N-carbamyl-L-aspartate are pH 6.0 and 8.2, respectively. The Km values for N-carbamyl-L-aspartate and for L-dihydroorotate are 0.13 and 0.07 mM, respectively. Inhibitor studies indicate that zinc may be involved in the catalytic activity of the enzyme.

Amidohydrolases↗
PubMed1976

Histamine levels in plasma, blood, and urine in severe asthma, and the effect of corticosteroid treatment.

Plasma, whole blood, and urinary histamine levels have been determined in 64 normal subjects, in 10 patients with severe asthma, and in 10 control patients with other illnesses. The mean whole blood levels did not differ between the three groups. The mean plasma level in the asthmatics was significantly greater than that of the normal subjects but not of the control patients. The urinary histamine output was lower in the control patients than in the normal subjects but in the asthmatics did not differ from that of the normals. Corticosteroid therapy caused a marked fall, often to barely detectable levels, of the whole blood histamine concentration of the asthmatic patients and restored the plasma levels to normal but did not affect urinary histamine levels.

Adult↗