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Biomedical subjects

M Rehahn

Publications and source records attributed to M Rehahn.

13 recordsLinked to original sources
PubMed2002

The distribution of counterions around synthetic rod-like polyelectrolytes in solution: a study by small-angle X-ray scattering and by anomalous small-angle X-ray scattering.

An investigation of the radial distribution of the counterions of a synthetic rodlike polyelectrolyte in aqueous solution is presented. The cationic polyelectrolyte used here has a poly(p-phenylene) backbone. For typical molecular weights the macroion comprises approximately one persistence length (ca. 20 nm) and effects of finite stiffness may be disregarded. Each repeating unit bears four charges which leads to a charge parameter of xi = 6.65. The distribution of the iodide counterions around this highly charged macroion is studied by small-angle X-ray scattering (SAXS) in dilute aqueous solution. These investigations are supplemented by measurements using anomalous small-angle X-ray scattering (ASAXS) that furnishes additional information about the contrast of the macroion. Data taken at high scattering angles give indication for contributions caused by the longitudinal fluctuations of the counterions. After correction for this effect the experimental results are compared to intensities calculated by use of the Poisson-Boltzmann (PB)-cell model. It is found that the PB-cell model describes the corrected data at intermediate and high scattering angles. Deviations at low scattering angle are attributed to the mutual interaction of the rod-like polyelectrolyte that can be described in terms of an effective structure factor. Data taken at lowest scattering angles point to a weak attraction between the rod-like macroions.

Journal Article↗
PubMed1988

Survival of lung cancer in East London: a prospective survey.

Five hundred men and 76 women all under the care of one physician at the London Chest Hospital were diagnosed as having bronchogenic carcinoma and admitted to a prospective survey between May 1966 and April 1978. The survey was completed in December 1984 when all but 19 of the 500 men had died. None was lost to follow up. The longest period of surveillance was 18 years 7 months, the shortest 6 years 8 months. The five-year survival of the group of 500 men was 7.6% (38), and 22% (32) for the 145 patients who had had resections. Of the 78 patients (63 men, 15 women) who had small cell carcinoma, only one survived 3 years; the others died in under 2 years, giving a median survival of 5 months. The median survival of the 21 untreated cases in this group of small cell carcinoma was 2 months.

Adult↗
PubMed1984

Effects of prednisolone in chronic airflow limitation.

A double-blind, randomised, placebo-controlled, crossover trial of prednisolone (40 mg daily for 14 days) was carried out in 43 patients with chronic airflow limitation (mean age 60 years, mean FEV1 1.02 litres, FEV1/FVC ratio 43.7%). Several subjective and objective variables for response were measured. Significant improvements occurred with prednisolone in most variables measured, but improvements also occurred with placebo in some variables. The improvements with prednisolone in general wellbeing, 12 min walk distance, peak expiratory flow, FEV1, and relaxed vital capacity were significantly greater than those with placebo. Clinical assessment and assessment of atopic status did not reveal any feature of major predictive value for steroid responsiveness. A proportion of patients with chronic airflow limitation do improve on oral corticosteroids and the continued use of such trials in clinical practice is justified, though a placebo period should be included, and several variables for response should be measured.

Adult↗
PubMed1984

Comparison between the effects of inhaled isoprenaline and fenoterol on plasma cyclic AMP and heart rate in normal subjects.

The time course of changes in plasma cyclic AMP, heart rate and bronchial tone after inhalation of fenoterol or isoprenaline from a dose-metered aerosol are reported in a group of normal subjects. After isoprenaline, plasma cyclic AMP increased rapidly reaching a peak by 10 min and returned to basal levels within 60 min. A rapid, transient rise in heart rate occurred that was maximal by 5 min and returned to a basal level by 45 min. After fenoterol, the changes in cyclic AMP and heart rate were of much longer duration. The rise in plasma cyclic AMP was slower in onset and of greater magnitude than for isoprenaline, reaching a peak by 20 min and remaining above basal level for more than 6 h. The maximum increase in heart rate after fenoterol was less than that observed with isoprenaline but an elevated rate persisted for 4 h after inhalation of fenoterol. Fenoterol is known to have a longer duration of action as a bronchodilator in comparison with isoprenaline. The prolonged rise in plasma cyclic AMP in normal subjects given inhaled fenoterol may reflect this long duration of action. The concomitant rise in heart rate, however, suggests that the duration of plasma cyclic AMP response may in part be due to the systemic effect of the fraction of inhaled fenoterol known to be absorbed via the buccal and intestinal routes.

Absorption↗
PubMed1984

Psychological changes and improvement in chronic airflow limitation after corticosteroid treatment.

Corticosteroids may produce mood changes. This could account for improvement in patients with chronic airflow limitation following trials of oral corticosteroid treatment as mood elevation might improve performance in objective measurements. This proposition was tested in 21 patients with chronic airflow limitation, who underwent detailed psychological assessment during a randomised controlled double blind crossover trial of the effect of prednisolone 40 mg daily compared with that of a placebo. Self rating visual analogue scales for various qualities of mood were completed before the study and after each phase in addition to depression and psychological symptom questionnaires. After treatment with the placebo, patients showed increases in cheerfulness (p less than 0.01) and sociability (p less than 0.01) and a decrease in depression (p less than 0.01). After treatment with prednisolone there were increases in cheerfulness (p less than 0.01), optimism (p less than 0.01), activity (p less than 0.05), and sociability (p less than 0.02) and there was a decrease in depression (p less than 0.01). When placebo and prednisolone values were compared, however, there were no significant differences. Some patients showed improvements (greater than 20%) in peak expiratory flow, FEV1 or forced vital capacity (FVC) after prednisolone, but nearly all had improvements in at least one psychological test. There were no detectable associations between changes in objective measurements and changes in psychological test ratings. This study suggests that in patients with chronic obstructive lung disease significant psychological changes are no more likely to follow treatment with a corticosteroid than treatment with a placebo and that physiological improvement after corticosteroid treatment is not tied to psychological changes.

Aged↗
PubMed1983

Are "pink puffers" more breathless than "blue bloaters"?

Breathlessness, disability, and exercise tolerance were assessed in 26 patients with severe chronic airflow limitation (forced expiratory volume in one second (FEV1) less than or equal to 1 litre) divided into two groups--15 patients who were normocapnic (pressure of arterial carbon dioxide (Paco2) less than 5.5 kPa (less than 41.4 mm Hg)), and 11 patients who were hypercapnic (Paco2 greater than 6 kPa (greater than than 45.1 mm Hg)). The two groups were well matched for spirometric values (FEV1 0.59 1 and 0.62 1, respectively). All of the hypercapnic patients could improve blood gas tensions towards normal by hyperventilation. There were no significant differences in visual analogue scores of breathlessness during treadmill exercise, disability (oxygen-cost diagram, dyspnoea grade), or exercise tolerance (six-minute walk, maximal consumption of oxygen during bicycle ergometry, distance walked to exhaustion in progressive treadmill test). The findings show that the "fight" to maintain normal blood gas tensions in the face of severe airflow limitation does not have an appreciable cost in terms of disability.

Carbon Dioxide↗
PubMed1981

Critical analysis of endomyocardial biopsies from patients suspected of having cardiomyopathy. II: Comparison of histology and clinical/haemodynamic information.

Endomyocardial biopsies showing histological evidence of "ordinary" hypertrophy or changes compatible with congestive cardiomyopathy (COCM) were obtained from 125 patients. Statistical analysis compared histological/morphometric data with clinical/haemodynamic findings such as ejection fraction, left ventricular end-diastolic pressure, and length of history. Patients were grouped either according to the histological description or the clinical diagnosis. Comparison of the morphological description with the final clinical diagnosis was also undertaken. Follow-up of the patients was between two and 66 months. The results of the statistical analyses showed no correlation between quantitative, morphological assessment and either clinical information, that is length of history and subsequent course, or the haemodynamic variables. In 86 per cent of cases a rough agreement between the morphological description and the clinical diagnosis was obtained, but no specific pattern permitting a morphological diagnosis of COCM was established. The findings suggest that pronounced topographic variation in biopsy material exists and that, therefore, the severity of COCM or its prognosis cannot be assessed from histological changes.

Adolescent↗
PubMed1979

Work-related respiratory disease in employees leaving an electronics factory.

Examination of the records of employees leaving an electronics factory over three-and-a-half years showed that a significantly greater proportion left the shop floor (where soldering took place) because of ill health than left the stores and office areas. This difference was largely due to work-related respiratory disease in those whose job was soldering. Shop floor workers leaving for health reasons also had increased sickness certification due to respiratory illness compared to stores and office workers. These findings suggest that work-related respiratory illness is a significant cause of morbidity and loss of employment in solderers working at the factory and that this has been a longstanding problem with its onset before the first recorded cases of occupational asthma caused by solder flux containing colophony.

Adolescent↗
PubMed1979

Late deaths after resection for bronchial carcinoma.

1267 patients who underwent surgical treatment for bronchial carcinoma during the period 1949--70 have been studied. 304 underwent thoracotomy without further resection; 88% died within 12 months; the maximum survival was 56 months. Of the remaining 963 patients, 869 late deaths are recorded, and the causes of these have been studied. The 5-year actuarial survival rate was 25.9%; the 10-year rate 15.3%; the 15-year rate 9.3%; and the 20-year rate 3.9%. 610 of the 869 deaths were due to bronchial carcinoma; 79 were due to respiratory disease; 57 to coronary disease; and 23 to other neoplasms. The percentage of total deaths due to bronchial carcinoma declined with the passage of time. It was 86.5% during the first year; 79.2% during the next 4 years; 53.7% from 5 to 10 years; and 39.3% over 10 years. The second commonest cause of death was respiratory disease, which tended to be related to the extent of resection. Compared with a population of the same age and sex structure, suffering the death rates of England and Wales during the period involved, these patients show a massive excess of deaths from bronchial carcinoma and a smaller excess from respiratory disease; and a considerable shortfall from coronary disease, other carcinomas, and all other causes. A more favourable probability of survival was linked with lobectomy, squamous cell type and the younger age group. A less favourable probability was linked with pneumonectomy, adenocarcinoma and older age-groups. There was no significant difference due to sex. After the first 2 years, with their heavy death rate, the chances of surviving to 10 years improved by about 15% each year.

Adult↗