Accurate measures of changes in regional lung air volumes from chest x-rays of small animals.

Objective. To develop a robust technique for calculating regional volume changes within the lung from x-ray radiograph sequences captured during ventilation, without the use of computed tomography (CT).Approach. This technique is based on the change in transmitted x-ray intensity that occurs for each lung region as air displaces the attenuating lung tissue.Main results. Lung air volumes calculated from x-ray intensity changes showed a strong correlation (R2= 0.98) against the true volumes, measured from high-resolution CT. This correlation enables us to accurately convert projected intensity data into relative changes in lung air volume. We have applied this technique to measure changes in regional lung volumes from x-ray image sequences of mechanically ventilated, recently-deceased newborn rabbits, without the use of CT.Significance. This method is suitable for biomedical research studies,enabling quantitative regional measurement of relative lung air volumes at high temporal resolution, and shows great potential for future clinical application.

Hydrodynamic effects on animal cells grown in microcarrier cultures. Reprinted from Biotechnology and Bioengineering, Vol. 29, Issue 1, Pages 130-141 (1987).

Hydrodynamic phenomena in microcarrier cultures are investigated with regard to the development of improved reactor designs for large-scale operations. New concepts and theoretical models that describe new data as well as previously published data are presented.

Exchange transfusion of whole blood in the treatment of cerebral malaria.

A case of cerebral malaria in a young British traveller, successfully treated by exchange transfusion of whole blood, is reported and the literature regarding the use of this technique in P. falciparum malaria is briefly reviewed.

Use of a radiometric technique for rapid sensitivity testing of mycobacteria in Scotland: the first year's experience.

We report the first year's experience of the use of a radiometric technique for sensitivity testing of mycobacterial isolates in Scotland. The techniques (using the Bactec 460 instrument) was much quicker than conventional methods (for example the mean time to obtain results for 60 strains of M.tuberculosis was 14.4 days, compared with 44.9 days for conventional methods). There was good agreement between results obtained by the two methods. Preliminary results also indicated the value of the radiometric technique for rapid isolation of mycobacteria from clinical samples (mean of 10.6 days with the radiometric technique compared with 26.7 days using egg media) although for optimal recovery, both techniques should be used in parallel.

Identification of Branhamella catarrhalis in 2.5 min with an indoxyl butyrate strip test.

Branhamella catarrhalis, an occasional cause of human respiratory infections, unlike most other members of the family Neisseriaceae, produces a butyrate esterase. This is capable of breaking the ester linkage between butyryl groups and carrier molecules. B. caviae and B. ovis, which are rarely encountered in pathological specimens, also produce butyrate esterase. This property can be used as a rapid test in the identification of B. catarrhalis. The recently reported rapid test for butyrate esterase relies on the release of methylumbelliferate, which can be detected only by using UV light after 5 min of incubation. In the rapid test described here, indoxyl is liberated from indoxyl butyrate by butyrate esterase and spontaneously forms indigo in the presence of oxygen. B. catarrhalis can be distinguished from other oxidase-positive, gram-negative cocci after 2.5 min by inoculating the organism onto a filter paper strip containing this compound.

Growth and death in overagitated microcarrier cell cultures.

The effects of hydrodynamic forces on cell growth are investigated for animal cells growing on microcarriers. A reduction in net growth was observed with high levels of agitation. DNA measurements indicated that the reduction in net growth was due entirely to cell death, from hydrodynamic forces. No inhibition or enhancement of cell replication appeared to occur with high levels of agitation.

Viscous reduction of turbulent damage in animal cell culture.

Animal cells are exposed to turbulent fluid flow in many cell culture processes. If the turbulence in the flow is sufficiently strong, the cells will be damaged or killed by fluid-mechanical forces. Through an increase in viscosity, the turbulence can be damped and the hydro-dynamic damage can be reduced. In this article, new experimental results are presented which illustrate the protective effect of thickening agents. The results follow the prediction of a model based on Kolmogorov's theory of universal equilibrium in turbulent flow fields.

Pneumonia due to Branhamella catarrhalis.

In 12 of 451 patients diagnosed as having pneumonia in a single hospital over 18 months the causative organism appeared to be Branhamella catarrhalis.

Effects of microcarrier concentration in animal cell culture.

Results are presented which show how the microcarrier concentration affects the hydrodynamic environment in animal cell bioreactors. At low levels of agitation, no physical effects of microcarrier concentration were found. However, cell growth was strongly influenced by cell concentration. At high levels of agitation, a strong detrimental effect of microcarrier concentration was found. A new mechanism of hydrodynamic damage was identified which is second order in microcarrier concentration. The identification of this mechanism adds to the fundamental understanding of hydrodynamic phenomena in microcarrier bioreactors.

Imipenem-cilastatin in the treatment of respiratory infections in patients with chronic airways obstruction.

Chest infections with organisms resistant to conventional antibiotics are common in patients with chronic lung disease. We have studied the use of imipenem in 40 (28 M 12 F) patients admitted for treatment of chest infections. Patients were treated with imipenem 0.5 g four times daily by intravenous infusion for 6.3 +/- 1.6 (S.D.) days. Forty-six respiratory pathogens were cultured from 36 patients including 18 Haemophilus influenzae, 6 H. parainfluenzae, 6 Streptococcus pneumoniae, 8 Pseudomonas aeruginosa, and 6 Branhamella catarrhalis. Forty-three of the 46 isolates were sensitive to imipenem, 28 to ampicillin, 33 to tetracycline and 35 to cotrimoxazole. Thirty-eight of the 40 patients improved clinically, and 34 of the 36 patients with positive sputum culture had no pathogens in their sputum after treatment. Twenty patients developed minor phlebitis at the infusion site but there were few other side effects. Imipenem may prove useful in the treatment of chest infections, particularly when the organism is resistant to conventional antibiotics.

Characterisation of Branhamella catarrhalis and differentiation from Neisseria species in a diagnostic laboratory.

To distinguish Branhamella catarrhalis from Neisseria species a study of 140 strains was made on simple laboratory media, with particular reference to deoxyribonuclease (DNase) production, superoxol reaction, and growth characteristics. All 97 clinical isolates of B catarrhalis (58 of which were beta-lactamase positive) and eight strains of B catarrhalis from the National Collection of Type Cultures were DNase positive and superoxol positive. None grew on modified New York City medium, modified Thayer Martin medium, MacConkey agar, crystal violet blood agar, nor under anaerobic conditions. Of the 16 different non-pathogenic Neisseria species tested, all were DNase negative, eight (50%) were superoxol reaction negative, and 13 (81%) grew on crystal violet blood agar. Using simple laboratory media, DNase, and superoxol tests, it was possible to identify B catarrhalis and to distingish it from pathogenic and non-pathogenic Neisseria species.

Hydrodynamic effects on animal cells grown in microcarrier cultures.

Hydrodynamic phenomena in microcarrier cultures are investigated with regard to the development of improved reactor designs for large-scale operations. New concepts and theoretical models that describe new data as well as previously published data are presented.

Lack of immunoglobulin A1 protease production by Branhamella catarrhalis.

Clinical isolates of Branhamella catarrhalis from the sputum of 20 patients with acute bronchopulmonary infection were examined for synthesis of immunoglobulin A1 protease by immunoelectrophoresis. Ten strains produced beta-lactamase, and 10 were beta-lactamase negative. None of the strains demonstrated immunoglobulin A1 protease activity despite the fact that three different culture media were used.

Increase in bronchopulmonary infection due to branhamella catarrhalis.

In a six month prospective study during the winter Branhamella catarrhalis was isolated from the sputum of 63 patients with symptoms of bronchopulmonary infection: 49 isolates were in pure culture and 14 were with another pathogen, Haemophilus influenzae being the commonest (found with 10 of the 14 B catarrhalis isolates). Of 36 patients infected in the community, 26 required admission to hospital. The remaining 27 patients were infected while in hospital. Forty four of the 63 isolates produced beta lactamase; 26 of these had been acquired in the community. As a result 29 patients were treated inappropriately with ampicillin and did not respond to this treatment. beta Lactamase produced by B catarrhalis may also protect other pathogens normally susceptible to beta lactam antibiotics. Most patients had chronic lung diseases or lung cancer, but three otherwise healthy patients who did not smoke developed bronchitis. B catarrhalis contributed to the death of five patients. A survey of the antibiotic prescribing habits of the referring general practitioners together with the sensitivity results of B catarrhalis suggest that changes in antibiotic prescribing habits in the community may be responsible for the increase in B catarrhalis infection.

The incidence and antibiotic susceptibility of Branhamella catarrhalis in respiratory infections.

The incidence of Branhamella catarrhalis in respiratory infections at City Hospital, Edinburgh from January 1981 to April 1984 is described. Beginning in January 1982 there was an increased incidence associated with a high proportion of beta-lactamase-producing strains. The number of these strains increased: from January 1981 to April 1983, 61% of strains produced beta-lactamase, and 83% produced beta-lactamase from January to April 1984. 53% of patients were infected in hospital. Environmental studies showed that 7% of staff and 8% of patients were carriers; there was also circumstantial evidence of ward and patient-to-patient infection. The antimicrobial susceptibility of 54 clinical strains was tested: all strains were resistant to trimethoprim but were susceptible to clavulanic acid plus amoxycillin, chloramphenicol, erythromycin, co-trimoxazole, cefotaxime and cefuroxime. beta-Lactamase-negative strains were uniformly susceptible to penicillin and ampicillin.