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Biomedical subjects

B D Harrison

Publications and source records attributed to B D Harrison.

At least 55 records · Page 3Linked to original sources
PubMed1993

Serological relationships and epitope profiles of isolates of okra leaf curl geminivirus from Africa and the Middle East.

A panel of seven murine monoclonal antibodies (mAbs) was raised against particles of okra leaf curl virus (OLCV), a whitefly-transmitted geminivirus which is prevalent in West Africa. The mAbs detected at least six distinguishable epitopes, two continuous and four discontinuous. In tests with these mAbs, relatively little antigenic variation was found among 24 OLCV isolates from Burkina Faso, Chad, Ghana, Ivory Coast, Nigeria, Oman and Saudi Arabia, each virus isolate reacting with at least five of them. However, on the basis of their reactions with 17 mAbs raised against particles of a group A isolate of African cassava mosaic virus (ACMV), the OLCV isolates could be assigned to two groups, which have geographical distributions that overlap in West Africa. A network of antigenic relationships was revealed by reactions between the OLCV mAbs and other whitefly-transmitted geminiviruses from six plant species in 12 countries. OLCV shared the most epitopes with tobacco leaf curl (African isolates) virus, ACMV, Indian cassava mosaic virus and bean golden mosaic virus. Selected OLCV mAbs are suitable for routine detection of OLCV, and a panel of three mAbs can be used to identify it.

Africa, Western↗
PubMed1993

Nucleotide sequence evidence for the occurrence of three distinct whitefly-transmitted geminiviruses in cassava.

The complete nucleotide sequence of the DNA of Indian cassava mosaic virus (ICMV) and a key part of that of a group B isolate of African cassava mosaic virus from Malawi (ACMV-M) were determined and compared at the nucleotide and encoded amino acid levels with the published sequences of an ACMV group A isolate (ACMV-K) and other whitefly-transmitted gemini-viruses (WTGs). The DNA of ICMV consists of two circular single-stranded molecules, DNA-A [2815 nucleotides (nt)] and DNA-B (2645 nt), which differ substantially in sequence from the genome components of ACMV-K (DNA-A 70%, DNA-B 47% sequence identity) and other WTGs. ICMV DNA-A contains eight open reading frames (ORFs) encoding proteins of > 100 amino acid residues, of which four ORFs (one genome sense, three complementary sense) are comparable to those of other WTGs. DNA-B contains one ORF in each sense, as in other WTGs. None of the putative viral proteins are more similar in amino acid sequence to the proteins of ACMV-K than to those of another WTG. The coat protein of ACMV-M is more like that of tomato yellow leaf curl virus from Sardinia (86% sequence identity) than those of ICMV or ACMV-K. The intergenic regions of ACMV-K, ACMV-M and ICMV DNAs differ in size, and largely in sequence, except for two 30 to 40 nt sequences which are also conserved in other WTGs and can form stem-loop structures. The intergenic region of ICMV DNA contains three copies of a 41 nt sequence, and that of ACMV-M DNA contains an imperfect repeat of a 34 nt sequence which resembles the repeated sequence in ICMV DNA. The differences between ACMV-K, ACMV-M and ICMV are considered great enough to justify their separation as isolates of three distinct WTGs: African cassava mosaic virus, East African cassava mosaic virus and Indian cassava mosaic virus.

Amino Acid Sequence↗
PubMed1993

Signal for potyvirus-dependent aphid transmission of potato aucuba mosaic virus and the effect of its transfer to potato virus X.

A British isolate of potato aucuba mosaic potexvirus (PAMV) was transmitted by aphids (Myzus persicae) which had fed previously on a source of potato Y potyvirus (PVY). Nucleotide sequence analysis of the PAMV coat protein gene indicated that amino acid residues 14 to 16 from the N terminus of the coat protein have the sequence DAG, which is also found in the coat proteins of potyviruses and is required for their aphid transmissibility. A recombinant virus isolate (TXPA7) was produced in which a segment of the coat protein gene of PAMV encoding the 40 N-terminal amino acids was inserted in the genome of potato X potexvirus (PVX) in place of the segment encoding the 28 N-terminal amino acids of PVX coat protein. This isolate, and a second similar recombinant (TXPA5) in which the DAG motif was changed to YTS, were mechanically transmissible to intact plants, in which they caused slightly milder symptoms than PVX. Particles of TXPA7 reacted in immunosorbent electron microscopy with PVX- and PAMV-specific antibodies and so were antigenically distinguishable from PAMV and PVX particles, which reacted only with their homologous antibody, and from TXPA5 particles, which reacted only with the PVX antibody. Recombinant TXPA7 was transmitted by aphids that had already fed on a source of PVY whereas TXPA5 and PVX were not. TXPA7 was not transmitted by aphids that had not fed on a PVY source. It is concluded that (i) the potyvirus-dependent aphid transmissibility of PAMV results from possession of a domain which includes the DAG motif and is located near the N terminus of the virus coat protein, and (ii) potyvirus-dependent aphid transmissibility can be conferred on PVX, a non-aphid-borne potexvirus, by substituting this domain for the N-terminal part of its coat protein.

Amino Acid Sequence↗
PubMed1993

A district confidential enquiry into deaths due to asthma.

BACKGROUND: The aim was to establish a continuing district based confidential enquiry into deaths from asthma. METHODS: A confidential enquiry was conducted in an English health district. Subjects comprised 24 residents of the Norwich health district aged between 16 and 65 years who had died between 1988 and 1991 with asthma as the principal cause of death. RESULTS: Twenty one of the patients (88%) died away from hospital. Overall the routine asthma management was appropriate in all respects in only four patients. In five cases the drug treatment was considered inappropriate, in 10 cases (42%) there was no written evidence that the patient had received advice and education, and only six cases had a written management plan. In 17 patients (71%) the fatal attack of asthma developed rapidly (in under three hours). The medical care during the final attack was found to have been inappropriate in six cases. Seventeen cases (71%) had psychological or social factors that were considered to have been of potential importance. CONCLUSIONS: This study has shown the feasibility of organising a confidential enquiry into asthma deaths within a health district. The distinguishing features of such an enquiry are that it is continuing, that the quality of care given to those patients who died is compared against a recognised standard, and that there is a structured system for feeding back the conclusions of the enquiry to the local medical community.

Asthma↗
PubMed1993

Audit in acute severe asthma--who benefits?

This paper reviews published audit activity for a single common condition (asthma). Has this effort brought about better care for the patient? The result of this audit of audits reveals that specialists do follow the guidelines on the management of acute asthma with good results, but that general physicians, in whose care perforce many acute episodes are managed, do not seem to be aware of the published good practice guidelines.

Acute Disease↗
PubMed1992

A criterion based audit of inpatient asthma care. Closing the feedback loop.

We have assessed the care of patients admitted to a specialist respiratory medical ward acutely ill with asthma, using a criterion based audit derived from a standard management protocol already in use in our hospitals. The audit was first performed from 01.01.90 to 31.08.90; after implementing certain changes, the audit was repeated from 1.12.90 to 31.1.91. Special attention was paid in each audit review to pre-admission measures, inpatient management and pre-discharge and follow-up management. During both audit periods, of a total of 78 patients, 74 patients gave a reason for the worsening of their asthma; 59 had had PEF measured and 58 had received systemic steroids before admission; 77 patients had full objective assessment of severity on admission; 76 patients were discharged on oral steroids; 62 had PEF meters for home monitoring; and 65 of the 68 patients who lived in our district were seen again within six weeks as outpatients in the chest clinic. However, only 30/55 (54%) had PEF variability of 20% or less (our criterion for appropriateness of discharge, in the first audit period) and only 32/55 had a written check on their inhaler technique in the first audit period. By relaxing our PEF criterion for discharge (in line with national guidelines), by introducing a stamp for recording that inhaler technique had been checked, and with encouragement and exhortation from senior staff, we improved our performance of meeting the set standards to 17 of 23 (74%) patients for PEF variability and to 22 of 23 (96%) patients for written check on inhaler technique in the second audit period.(ABSTRACT TRUNCATED AT 250 WORDS)

Aftercare↗
PubMed1991

Audit in respiratory disease.

Respiratory medical audit is discussed in terms of Structure, Process and Outcome with a description of the audit Feedback Loop of monitoring, assessment, improvement followed by further monitoring and assessment. Methods of monitoring include sentinel case, criterion-based, small group comparison, surveys and peer review. There are professional, social and pragmatic reasons for audit which is the responsibility of the provider professionals and requires adequate resources.

Humans↗
PubMed1991

Airflow limitation in sarcoidosis--a study of pulmonary function in 107 patients with newly diagnosed disease.

One hundred and seven patients with sarcoidosis attended for pulmonary function testing within 2 weeks of diagnosis. In four Stage 0, 42 Stage I, 32 Stage II, 26 Stage III and three Stage IV patients physiological abnormalities increased with increasing stage. The commonest abnormality, airflow limitation, occurred in 61 patients; a low transfer factor occurred in 29; a restrictive defect, the least common abnormality, occurred in seven. Fifty-nine patients and 30 of those with evidence of airways obstruction never smoked. None of the 52 patients with airflow limitation tested after bronchodilator inhalation demonstrated significant reversibility. All patients with obstruction had evidence of small airways narrowing. The majority had an FEV1/FVC ratio below 75%. Fourteen patients also had a low peak expiratory flow indicative of large airway narrowing. Airflow limitation occurs in all stages of sarcoidosis and should always be looked for in patients with sarcoidosis who have respiratory symptoms.

Adult↗
PubMed1991

Nuclear location of the 16K non-structural protein of tobacco rattle virus.

An antiserum, elicited by a synthetic peptide coupled to bovine serum albumin, reacted specifically with the non-structural 16K protein of tobacco rattle virus. The protein was detected in extracts of systemically infected Nicotiana clevelandii leaves, but only in those made with the aid of SDS, urea and 2-mercaptoethanol. Immunogold labelling of ultrathin sections showed that the protein was mainly associated with nuclei, but was also present in the cytoplasm. These observations suggest that the 16K protein binds to macromolecular components of infected cells, especially in nuclei, but do not clarify its function.

Amino Acid Sequence↗
PubMed1990

The outcome of community acquired pneumonia treated on the intensive care unit.

Eighteen patients with community acquired pneumonia required intensive care for severe or progressive hypoxaemia, rising arterial carbon dioxide tension or respiratory arrest, and 17 received intermittent positive pressure ventilation. Thirteen survived to leave hospital and 12 are long term survivors. Ventilation was started within 4 days of admission in all cases and was continued for up to 34 days; six patients required ventilation for over 3 weeks. The most common medical complication was renal failure. The most common iatrogenic complication was pneumothorax. We believe that all the hypoxic patients would have died from their hypoxia had it not been corrected. We estimated that up to 5% of patients admitted with community acquired pneumonia need intensive care. This study demonstrates the effectiveness of such care, which is multidisciplinary, demanding, and may need to be prolonged.

Carbon Dioxide↗
PubMed1990

Bronchoscopic and bronchographic findings in 12 patients with sarcoidosis and severe or progressive airways obstruction.

Twelve patients (8 men), aged 33-67 (mean 49) years, with histologically proved sarcoidosis underwent bronchoscopy. All had symptoms, signs (wheeze in 11, high pitched inspiratory "squeaks" in six, stridor in three), and physiological abnormalities characteristic of severe or worsening airways obstruction. Eleven patients also underwent bronchography. At the time of bronchoscopy four patients had stage II, one stage III, and seven stage IV sarcoidosis. All patients had a peak expiratory flow (PEF) of 70% predicted or less and a maximum expiratory flow at 50% (MEF50) and 25% (MEF25) of vital capacity below 35% predicted. The ratio of their forced expiratory volume in one second to forced vital capacity (FEV1/FVC) ranged from 37% to 65%. Fibreoptic bronchoscopy showed single or multiple areas of segmental bronchial stenoses in 10 patients, two of whom had stenotic webs. Bronchography showed that the sites and severity of stenoses were more widespread than suspected from the bronchoscopic findings. Five of the 11 patients undergoing bronchography had bronchiectasis, which was restricted to the upper lobes in three and a lower lobe in one and affected both upper and lower lobes in one patient. The bronchiectasis had not been suspected or diagnosed from the chest radiography or the bronchoscopy.

Adult↗
PubMed1990

An attempt to determine the optimal duration of hospital stay following a severe attack of asthma.

The optimal duration of hospital stay following admission for acute severe asthma is difficult to determine. An asthmatic is at particularly high risk of sudden death in the 6-12 weeks after admission, and too early hospital discharge may add to this risk. Thirty patients hospitalised for severe asthma recorded peak flows thrice daily for 8 weeks following discharge. Peak flow charts were reviewed at monthly intervals, and dips were divided into 'minor' (peak flow less than 75% of the patient's best), 'major' (less than 50%) and 'catastrophic' (less than 30%). Fourteen of the 30 patients had major dips (including 4 who had catastrophic dips as well). Four of these 14 patients were readmitted with acute severe asthma during the 8 weeks follow-up period; in contrast, none of the 16 patients without major dips required readmission. The only in-hospital factor that correlated with and was predictive of (p less than 0.001) multiple major dips post-discharge was the peak flow variability in the 24 hours before discharge, defined as [(highest-lowest peak flow)/highest] x 100. Thirteen of the 14 patients with major dips had pre-discharge peak flow variation greater than 20% compared with only 2 of the 16 without major dips. We believe it is unwise to discharge asthmatics from hospital until the diurnal variation in their peak flow is below 20%. Discharging them before this target is reached puts them at increased risk of further severe attacks of asthma requiring re-hospitalisation.

Acute Disease↗