PubMed Health⌕ Search

Biomedical subjects

B F Johnson

Publications and source records attributed to B F Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1979

A comparison of the effects of labetalol, bendrofluazide and their combination in hypertension.

1 Bendrofluazide (10 mg/day) or labetalol (300 mg and 600 mg/day) produced significant reductions in lying, standing, and post-exercise blood pressure in ten hypertensives. 2 Active treatments were approximately equivalent in anti-hypertensive effect. However, comparing lying and standing determinations, labetalol (600 mg/day) produced significantly greater additional postural falls in systolic blood pressure than during placebo or bendrofluazide treatment. 3 Systolic blood pressure rose after exercise during placebo or bendrofluazide treatment. However, on labetalol, mean changes in systolic blood pressure after exercise were negative and significantly different from those seen on placebo. 4 Greater reductions in lying and post-exercise systolic blood pressure were produced by combination treatment than by either individual drug. Additional postural and exercise-related falls in systolic blood pressure tended to be smaller with combination treatment than during treatment with labetalol alone. 5 Labetalol significantly reduced lying, standing, or post-exercise heart rate by comparison with placebo or bendrofluazide. 6 Labetalol significantly reduced lying, standing, or post-exercise heart rate by comparison with placebo or bendrofluazide. 6 Labetalol moderately reduced plasma renin activity, whereas bendrofluazide caused marked elevation. The effect of bendrofluazide predominated during combination treatment.

Adult↗
PubMed1978

The comparative bioavailability of Lanoxin tablets and Lanoxicaps with and without sorbitol.

(1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P less than 0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P less than 0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P less than 0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.

Adult↗
PubMed1978

Effect of a standard breakfast on digoxin absorption in normal subjects.

The influence of food on absorption of digoxin was studied in 6 healthy volunteers who received 1.0 mg digoxin as 4 tablets of Lanoxin either after an overnight fast, immediately after a standard breakfast, or 90 min after a standard breakfast. There was no significant difference between the three regimens in terms of area under the plasma concentration-time curve for 79 hr or in the 10-day cumulative urinary excretion. The mean peak plasma concentration was higher (p less than 0.05) when digoxin was given fasting (4.2 +/- 0.46 ng/ml) than immediately after food (2.8 +/- 0.24 ng/ml). The mean peak plasma concentration when digoxin was administered 90 min after food (3.3 +/- 0.30 ng/ml) was intermediate but not significantly different from either of the other mean peak concentrations. The results demonstrate that ingestion of food decreases rate but not extent of absorption of concurrently administered digoxin.

Adult↗
PubMed1978

The influence of digoxin particle size on absorption of digoxin and the effect of propantheline and metoclopramide.

1 The influence of particle size on absorption of digoxin was studied in ten healthy volunteers who received 0.5 mg digoxin as two standard Lanoxin tablets, or tablets containing micronized digoxin or large particle size digoxin. Tablets were given 30 min after 15 mg propantheline, 10 mg metoclopramine or a placebo tablet, and following an overnight fast. 2 The overall mean cumulative 4 day urinary excretion of digoxin was significantly lower (P less than 0.01) after large particle size digoxin than after standard or micronized digoxin. Mean cumulative urinary excretion following large particle size digoxin was reduced when administered after metoclopramide and increased after propantheline, the difference between these two treatments being significant (P less than 0.05). There was a significantly lower (P less than 0.05) overall mean cumulative excretion following standard by comparison with micronized digoxin. However, by comparison with placebo, neither metoclopramide nor propantheline significantly altered mean cumulative excretion after standard or micronized digoxin. Propantheline and metoclopramide affect absorption of digoxin from formulations of large particle size and slow dissolution rate only.

Adult↗
PubMed1978

Influence of soft gelatin on digoxin absorption.

1 The influence of encapsulation in soft gelatin on the absorption of digoxin from a solvent mixture of polyethylene glycol 400 90% W/W, ethanol 6% W/W, propylene glycol 3% W/W and water 1% W/W was studied in eight healthy volunteers. 2 Each volunteer received 0.6 mg digoxin as solution alone, as three intact capsules containing digoxin solution, as three capsules containing digoxin solution sectioned in half and as three capsules containing digoxin solution dissolved in water prior to administration. 3 There was no significant difference between the four treatments in terms of area under the plasma concentration--time curves for 7 h, peak plasma concentrations, time to peak or in the cumulative urinary excretion for 6 days. 4 It is suggested that a constituent of the solvent rather than the presence of or encapsulation within soft gelatin may be the determining factor in enhanced absorption of digoxin from soft gelatin capsules as compared to aqueous solution or tablets of rapid dissolution rate.

Adult↗
PubMed1977

Genetic mapping of the lexC-113 mutation.

A mutation, previously designated lex-113 and suspected to be situated in the lexA locus, has been positioned by transductional studies to a unique site on the chromosome of E. coli B separate from the lexA102 and uvrA155 mutations. The order of genes in this chromosomal region was demonstrated to be malB-lexA-uvrA-lex-113. The allele designation lexC-113 is suggested for this mutation in a new gene functional in the regulation of inducible lex+ - and rec+-dependent SOS activities.

Chromosome Mapping↗
PubMed1977

The comparability of dosage regimens of Lanoxin tablets and Lanoxicaps.

1 Twice daily administration of 0.25 mg digoxin tablets (Lanoxin) or of 0.2 mg digoxin in solution in soft gelatin capsules (Lanoxicaps) produced similar mean steady state plasma digoxin concentrations in ten healthy volunteers. Respective values were 1.07 +/- 0.075 and 0.95 +/- 0.048 ng ml-1. 2 During continued administration, peak plasma concentrations occurred earlier after capsules with a tendency to higher peak levels. However, area under curve determinations over 7 h were similar. 3 Approximately 10% less digoxin was recovered in urine collected in a 12 h dosage interval during the lower dosage administration of capsules. Mean percentage urinary recovery of administered dose was 57% for tablets and 65% for capsules. 4 The enhanced bioavailability of Lanoxicaps was associated with reduced between-subject variability in plasma concentration. 5 Lanoxicaps (0.2 mg) should be approximately equivalent in effect to digoxin tablets (0.25 mg) currently available in the United Kingdom, though improved consistency would be anticipated.

Adult↗
PubMed1977

Transient changes in plasma digoxin concentration and the development of cardiotoxicity.

1. Eight dogs were given two infusions of digoxin 0.1 mg/kg, one over 9 min and the other one over 90 min in a randomized sequence, allowing at least 12 days between each experiment. 2. Digoxin plasma profiles reflected the rate of digoxin infusion, the peak concentration of drug attained at the end of each infusion being considerably higher but more transient after the 9 min than after the 90 min transfusion. 3. Digoxin reduced the amount of acetylstrophanthidin required to produce electrocardiographic evidence of cardiotoxicity. This increase in cardiac sensitivity at 150 and at 360 min after the start of the digoxin infusion was independent of rate of infusion. 4. These results suggest that the development of cardiotoxicity is dependent upon the quantity of digoxin delivered into the systemic circulation regardless of the plasma concentration. 5. By inference, cardiotoxicity is related solely to the amount and not the rate of absorption from a given dose of digoxin.

Animals↗
PubMed1977

Volume-related mitochondrial deoxyribonucleic acid synthesis in zygotes and vegetative cells of Saccharomyces cerevisiae.

The synthesis of mitochondrial deoxyribonucleic acid (DNA) in Saccharomyces cerevisiae cells has been examined during conjugation, in preconjugal conditions, and in control cultures that were not exposed to obverse diffusible sex factors. The ratios of mitochondrial to nuclear DNA varied from about 0.1 in control cells, to about 0.3 in alpha cells exposed for 180 min to cell-free culture medium from a cells, and to about 0.4 in conjugating cells 150 min after mixing. The enhanced levels of mitochondrial DNA during preconjugal and conjugal conditions seem correlated with enhanced cell volumes. Likewise, amounts of mitochondrial DNA in vegetative cells were found to be correlated with cytoplasmic volumes.

Conjugation, Genetic↗
PubMed1977

Initial care of hypertensive patients. Influence of different types of clinical records.

The initial record of history and clinical findings has been studied in 278 patients attending three hypertension clinics. Half of these were randomly allocated to standard case notes and the other half to a special structured questionnaire record. The investigations carried out in a total of 521 patients with raised arterial pressures were examined. The records derived from the structured questionnaire were much more complete than the standard case notes but the difference was less obvious for a positive record than a negative one. None of the investigations was carried out in all patients, even though it was the policy of the clinics that most of them should be. A possible aetiological diagnosis was made in 28 patients and, at the time of writing, 3 patients had benefited from a surgical operation carried out as a result of investigation. These results raise the question of the quality of the initial care of hypertensive patients and suggest that the structured questionnaires might lead to an improvement. It remains to be established whether all the information collected does influence the outcome in patients with hypertension.

Humans↗
PubMed1977

The transient anti-hypertensive effect of phentolamine in patients receiving beta-blocker treatment.

In seven hypertensives receiving beta-blocker drugs, and additional reduction in standing blood pressure occurred between 60 and 90 minutes after 40 mg phentolamine by mouth. The occurrence of the postural hypotensive effect was delayed in relation to the reported time of peak plasma concentration of unchanged phentolamine. Supine blood pressure and heart rate were unaffected. Phentolamine has no clinically useful anti-hypertensive effect in conjunction with beta-blockers in patients with essential hypertension.

Adult↗
PubMed1977

Fusion and erosion of cell walls during confugation in the fussion yeast (Schizosaccharomyces pombe).

Conjugation in Schizosaccharomyces pombe was studied by transmission electron microscopy. Mural and nuclear events were scored from induction, the initial event, to meiosis I, the start of sporulation. These morphogenic markers were separately identifiable as flocculation, copulation, conjugation-tube formation, cross-wall formation, cross-wall erosion, conjugation-tube expansion, cytoplasmic fusion, de-differentiation of site of union, nuclear migration and karyogamy. The following were identified as new structural elements: sex hairs, which presumably mediate hydrogen bonding between cells during flocculation; crimp at the site of union; dark patch, which presumably serves as a leak-proof seal at the time of cross-wall erosion; suture, an electron-dense seam formed by the union of a copulant pair; and small electron-dense particles close to the site of wall erosion. No special structures on the cell wall could be identified as indicative of specific sites for potential copulatory activity. The discontinuity of the 2 cell walls at the site of union became so de-differentiated after fusion and erosion that it was no longer possible to pinpoint the site of union.

Ascomycota↗
PubMed1976

Randomised controlled trial of computer-held medical records in hypertensive patients.

A total of 278 hypertensive patients in three clinics were randomly allocated to have their medical records held in a computer system (136) or on standard hospital notes (142). For the computer system the doctor completed a structured input form, and the information on symptoms, physical findings, and diagnoses was more complete than that in the standard notes. This resulted in certain symptoms and risk factors being recognised more often when the computer system was used. The hypertension clinics' routines were not disrupted by the introduction of a computer-held system, and follow-up consultation times were not affected by the type of records kept, although the first consultation took eight minutes longer when computer documents were completed. The patients remained in the trial for one year and clinical management was assessed from blood pressure control, drop-out rates, and the frequency of performing investigations. These estimates of management showed no significant difference between the two groups, but the attempt to tailor the computer system to help management made the system acceptable to the doctors using it. The computer system continues to be used and is providing data for research into hypertension.

Computers↗
PubMed1976

A completely absorbed oral preparation of digoxin.

Digoxin absorption was studied in healthy volunteers by determination of peak plasma concentrations, areas under plasma concentration curves, and urinary excretion after single-dose administration. By comparison with an aqueous solution, increased rate and extent of absorption occurred from experimental soft gelatin formulations of digoxin in solution. Enhanced bioavailability of the capsules was not affected by altered volume of contained solvent. Digoxin was considerably better absorbed from capsules than from tablets of moderately high dissolution rate. Mean percentage intestinal absorption was 75% from tablet and 97% from capsules. Reduced between-subject variability accompanied the enhanced absorption from capsules.

Administration, Oral↗