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Biomedical subjects

B D Harrison

Publications and source records attributed to B D Harrison.

At least 73 records · Page 4Linked to original sources
PubMed1989

Prediction of microbial aetiology at admission to hospital for pneumonia from the presenting clinical features. British Thoracic Society Pneumonia Research Subcommittee.

The selection of initial antimicrobial treatment in a patient with community acquired pneumonia is an important clinical decision. Because this decision is usually made before the results of specific microbiological tests are available, we attempted to determine how well the presenting clinical features would allow prediction of microbial aetiology in 441 adults admitted to hospital with pneumonia. Five of 90 variable available on admission were selected for inclusion in a multivariate discriminant function analysis because of their strong association with one or more of the major aetiological subsets (Mycoplasma pneumoniae, Streptococcus pneumoniae, "other," and undetermined). These variables were age, number of days ill before admission, presence or absence of bloody sputum and of lobar infiltration on chest radiograph, and white blood cell count. The microbial aetiology was correctly predicted by this discriminant function analysis in only 42% of cases, which gives a quantitative estimate of the degree of difficulty encountered in determining the microbial aetiology at the time of admission for pneumonia. When a similar discriminant function analysis was applied to the third of patients in whom the microbial aetiology was never determined, most of these cases were predicted to be due to Streptococcus pneumoniae.

Adolescent↗
PubMed1988

Molecular variation in vector-borne plant viruses: epidemiological significance.

Patterns of variation are examined in four groups of plant viruses, with special reference to their particle proteins and to changes in vector transmissibility and specificity. In the nepoviruses and potyviruses, non-circulative transmission, by nematodes and aphids respectively, seems dependent on structural features on the surface of the virus particles. The N-terminal part of the particle protein may play the key role in potyviruses. Similarly in the luteoviruses, and possibly in the geminiviruses, specificity of circulative transmission by aphids, whiteflies and leafhoppers is linked to the antigenic specificity of the virus particles. Among naturally occurring isolates of the same virus, variation seems often to be discontinuous, and is predominantly of two sorts. Minor variations, characterized by loss of an epitope or substitutions of a few amino acids, can be associated with loss of transmissibility in luteoviruses and potyviruses, or have no effect. Major variations are associated with differences in vector specificity and seem likely to involve radical genetic changes that have evolved over long periods. The adaptation of virus particle proteins for transmission by vectors probably results in conservation of the genes that encode them, and in greater conservation of some parts of these genes than of others.

Amino Acid Sequence↗
PubMed1988

Lymphocytic interstitial pneumonitis in association with Sjogren's syndrome.

We describe a patient with Sjogren's syndrome who developed what appeared to be fibrosing alveolitis. Transbronchial lung biopsy indicated lymphocytic interstitial pneumonitis (LIP), rather than fibrosing alveolitis, which was treated successfully with steroids. Both conditions are well recognized in association with Sjogren's syndrome and the distinction is important in view of the good response to therapy of LIP.

Diagnosis, Differential↗
PubMed1986

Need for intravenous hydrocortisone in addition to oral prednisolone in patients admitted to hospital with severe asthma without ventilatory failure.

52 severely ill asthmatic patients requiring acute admission to hospital entered a double-blind placebo-controlled trial to determine whether intravenous hydrocortisone given in addition to high-dose oral prednisolone and standard bronchodilator therapy accelerated recovery. Patients who had been given parenteral steroids before admission, by comparison with those who had not received such treatment, had been deteriorating for a shorter period before admission, had received more injected or nebulised bronchodilator therapy, and had higher admission peak flows. As judged by peak flow measurements 24 h after admission, parenteral steroids had no effect on the outcome, irrespective of whether they were given before or after (ie, intravenous hydrocortisone) admission. There is no evidence for the continued use of intravenous hydrocortisone in addition to oral prednisolone and bronchodilator therapy in patients admitted to hospital with severe asthma without ventilatory failure.

Acute Disease↗
PubMed1986

The clinical spectrum and diagnosis of Mycoplasma pneumoniae infection.

The clinical, radiographic and microbiological data of 47 patients with Mycoplasma pneumoniae infection admitted to three Norfolk hospitals during a 20-month period between 1982 and 1983 have been reviewed. Thirty-nine presented with pneumonia and eight with non-pulmonary infection. The M. pneumoniae specific IgM test was positive in 42 of 45 patients tested (89 per cent); in 39 the levels were diagnostic on admission. Cold agglutinins were detected in 27 (57 per cent) and a fourfold rise in complement fixation titre was demonstrated in 13 (29 per cent). Sputum culture was positive in 12 (26 per cent). The extrapulmonary manifestations observed were haemolytic anaemia (17 per cent), Stevens Johnson syndrome (4.1 per cent), neurological abnormalities (4.1 per cent), arthritis (2.1 per cent), hepatitis (2.1 per cent) and pericarditis (2.1 per cent). One patient with multilobe pneumonia, pericardial effusion and haemolytic anaemia died. Six patients presented with a history of illness longer than a month; in three the clinical and radiographic picture suggested chronic disease (pulmonary tuberculosis, lymphoma and unresolving pneumonia). There were no distinctive clinical or radiographic features of M. pneumoniae infection. Diagnosis, therefore, relies on serological tests of which the most useful is the rapid, specific IgM test, positive in 86 per cent of the admission sera.

Adolescent↗
PubMed1985

Usefulness and limitations of the species concept for plant viruses.

Continuing concerns among virologists are what range of isolates is covered by one virus name and whether such names relate to categories broadly equivalent to biological species of higher organisms. In the potyviruses, tobamoviruses, and probably other groups of plant viruses with monopartite RNA genomes, exchange of genetic information among isolates is not known to occur; our ability to delineate separate viruses apparently depends on the extent to which biological fitness involves several correlated changes in the genomes of variant clones. Although some such correlated changes are found where viruses infect different plant families, intergrading forms occur in many instances where the host ranges of variants overlap. In plant viruses with multipartite RNA or DNA genomes, the extent of gene pools can be assessed from the ability of isolates to form pseudo-recombinants by reassortment of their genome parts. In the nepoviruses, clusters of virus strains sharing a gene pool resemble, but seem more sharply delimited than, the clusters based on nucleotide sequence homology or serological specificity. In the tobraviruses gene pools do not coincide with serological groupings, and in the geminiviruses biologically very distinct entities have much genome homology and are closely related serologically. The biological species concept seems inappropriate or impractical for many plant viruses, and a more flexible and pragmatic approach to assigning virus isolates to nameable categories is advocated.

Cloning, Molecular↗
PubMed1984

Percutaneous Trucut lung biopsy in the diagnosis of localised pulmonary lesions.

In a prospective evaluation of percutaneous Trucut needle biopsy for localised intrathoracic lesions in 89 patients histological specimens were obtained in 81. Malignancy was diagnosed in 66 cases. Subsequently definitive histological reports were available in 18 of these patients with complete concordance of malignant cell type. Sixteen patients had non-malignant histological appearances, which were later confirmed objectively in six. In three patients there was no follow up information, but in the remainder the clinical course was entirely consistent with the histological appearances of the biopsy specimens. Adequate specimens were obtained from only two of the five lesions less than 2 cm in diameter. Lesions deeper than 8 cm from the site of biopsy were associated with significantly more haemorrhagic complications than more superficial lesions. Comparison with other series indicates that Trucut needle biopsy which produces histological specimens has greater diagnostic accuracy than cytological techniques for both malignant and non-malignant localised lesions. It is concluded that this technique has a definite place in the investigation of this common problem in carefully selected patients provided that strict attention is paid to the details of the technique.

Adult↗
PubMed1982

Assessment of steroid responsiveness in patients with chronic airflow obstruction.

A simple steroid trial was conducted to assess whether 31 patients with chronic airflow obstruction would benefit from oral steroid therapy. Peak expiratory flow (PEF), forced expired volume in 1 s (FEV1), and ratio of FEV1, to forced vital capacity (FVC) were monitored during a 6-month period (when patients were on maximum bronchodilator therapy), after 2 weeks on placebo and after 2 weeks on prednisolone 30 mg daily. Patients also measured that PEF at home thrice daily. None had a significant degree of steroid reversible airflow obstruction. The preliminary observation period (of at least 3 months) is important to prevent an improvement being attributed to steroids, when it has in fact occurred spontaneously or is the result of bronchodilator therapy or cessation of smoking.

Administration, Oral↗
PubMed1982

The use of the 12 minute walking test in assessing the effect of oral steroid therapy in patients with chronic airways obstruction.

The reproducibility of the 12 minute walking distance (12 MD) was assessed in ten men with chronic airways obstruction, and the 12 MD was used, together with spirometry, transfer factor and three subjective assessments of breathlessness to evaluate the effects on respiratory function of prednisone 30 mg daily given orally in double-blind placebo-controlled fashion for two weeks. Like others, we found the 12 MD reproducible on a single day with a mean variation of 3.1%. Tests performed two weeks apart showed greater variability ranging from 0.2% to 30.9%, (mean 9.1%). During placebo and prednisone therapy the 12 MD and assessments of breathlessness correlated significantly with each other and with TLCO, but not with spirometry. Following steroid therapy there was a significant increase in mean TLCO but no significant change in 12 MD, spirometry or subjective assessments. Changes in 12 MD and TLCO correlated significantly with each other and with changes in subjective assessments. Changes in FEV1 correlated with changes in breathlessness, and also with variability in FEV1 while receiving placebo. Individuals with the greatest changes in 12 MD and FEV1 were those with the greatest variability on placebo. The variability of the 12 MD and FEV1 should be measured in individuals before using these tests to assess response to steroid therapy.

Aged↗
PubMed1982

Genome reconstitution and nucleic acid hybridization as methods of identifying particle-deficient isolates of tobacco rattle virus in potato plants with stem-mottle disease.

NM isolates of tobacco rattle virus (TRV) are perpetuated by the larger genome nucleic acid (RNA-1) but do not produce nucleoprotein particles; their identification therefore presents special problems. Assays of the infectivity of nucleic acid extracts, and of previously frozen sap, suggested that such isolates occur in potato plants with stem-mottle disease. These isolates were identified by two tests. In the first, TRV nucleoprotein particles were produced in plants inoculated with a mixture of nucleic acid from diseased potato leaves and non-infective RNA-2 of an authentic culture of TRV, showing that the TRV genome had been reconstituted. In the second test, TRV RNA was identified in nucleic acid from diseased potato leaves by hybridization to 3H-labelled DNA complementary in nucleotide sequence to RNA-1 of the PRN strain of TRV. This cDNA test consistently identified TRV in stem-mottle affected potato plants grown in the glasshouse or in field crops. Although particle-producing isolates of TRV have been reported in potato, stem-mottle disease is apparently usually caused by infection with NM isolates.

DNA↗
PubMed1982

Recovery of hypothalamo-pituitary-adrenal function in asthmatics whose oral steroids have been stopped or reduced.

Hypothalamo-pituitary--adrenal (HPA) function was studied using tetracosactrin and insulin hypoglycemia tests in eleven asthmatic patients who were receiving or had taken oral steroids. The patients had been on prednisone, 5--20 mg/day for 2--17 years. As the dose was reduced they used beclomethasone inhalation, up to 800 micrograms/day. Seven insulin hypoglycemia tests were performed when the patients had been off oral steroids for 15--37 months. Plasma cortisol responses were normal in all seven, three had subnormal responses of ACTH. In five patients serial tetracosactrin and insulin hypoglycaemia tests were performed during reduction of steroid dose. Two patterns of recovery of HPA function were observed. In one, both hypothalamo--pituitary and adrenal function seemed to return simultaneously, in the other normal response to tetracosactrin appeared before that to insulin hypoglycaemia. One patient had normal ACTH and cortisol responses to the stress of a vasovagal attack, but failed to respond to subsequent hypoglycaemia. We conclude that a normal response to tetracosactrin does not indicate recovery of the HPA axis after stopping prolonged oral steroid therapy for asthma, and that patients should continue to carry steroid therapy cards for at least 5 years after such treatment has been discontinued.

Adrenocorticotropic Hormone↗