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Biomedical subjects

S Johnson

Publications and source records attributed to S Johnson.

At least 73 records · Page 4Linked to original sources
PubMed2001

Identification and characterization of a novel family of pneumococcal proteins that are protective against sepsis.

Four pneumococcal genes (phtA, phtB, phtD, and phtE) encoding a novel family of homologous proteins (32 to 87% identity) were identified from the Streptococcus pneumoniae genomic sequence. These open reading frames were selected as potential vaccine candidates based upon their possession of hydrophobic leader sequences which presumably target these proteins to the bacterial cell surface. Analysis of the deduced amino acid sequences of these gene products revealed the presence of a histidine triad motif (HxxHxH), termed Pht (pneumococcal histidine triad) that is conserved and repeated several times in each of the four proteins. The four pht genes (phtA, phtB, phtD, and a truncated version of phtE) were expressed in Escherichia coli. A flow cytometry-based assay confirmed that PhtA, PhtB, PhtD and, to a lesser extent, PhtE were detectable on the surface of intact bacteria. Recombinant PhtA, PhtB, and PhtD elicited protection against certain pneumococcal capsular types in a mouse model of systemic disease. These novel pneumococcal antigens may serve as effective vaccines against the most prevalent pneumococcal serotypes.

Amino Acid Sequence↗
PubMed2001

Use of a whole genome approach to identify vaccine molecules affording protection against Streptococcus pneumoniae infection.

Microbial targets for protective humoral immunity are typically surface-localized proteins and contain common sequence motifs related to their secretion or surface binding. Exploiting the whole genome sequence of the human bacterial pathogen Streptococcus pneumoniae, we identified 130 open reading frames encoding proteins with secretion motifs or similarity to predicted virulence factors. Mice were immunized with 108 of these proteins, and 6 conferred protection against disseminated S. pneumoniae infection. Flow cytometry confirmed the surface localization of several of these targets. Each of the six protective antigens showed broad strain distribution and immunogenicity during human infection. Our results validate the use of a genomic approach for the identification of novel microbial targets that elicit a protective immune response. These new antigens may play a role in the development of improved vaccines against S. pneumoniae.

Amino Acid Sequence↗
PubMed2001

Characterization of the secreted MPT53 antigen of Mycobacterium tuberculosis.

MPT53 is a secreted protein of Mycobacterium tuberculosis. Southern transfer and hybridization showed mpt53 to be conserved in the M. tuberculosis complex and to have homology with DNA from Mycobacterium avium and other nontuberculous mycobacteria. However, anti-MPT53 polyclonal antibodies detected no antigen in the culture filtrates of M. avium and other nontuberculous mycobacteria. MPT53 of M. tuberculosis induced strong, tuberculosis-specific antibody responses in guinea pigs but induced no delayed-type hypersensitivity. Involvement in immune responses during human tuberculosis was very modest.

Animals↗
PubMed2001

The acute and sub-chronic effects of levocetirizine, cetirizine, loratadine, promethazine and placebo on cognitive function, psychomotor performance, and weal and flare.

AIM: To compare the central and peripheral H1 inhibitory effects of acute and sub-chronic doses of levocetirizine (L-CTZ), cetirizine (CTZ), loratadine (LOR) and promethazine (PRM) versus placebo, using a battery of psychomotor and cognitive tests together with measures of the weal and flare reaction. PRM was included in the study as a positive internal control to validate the sensitivity of the psychometric test battery to the CNS effects of the various treatments. METHODS: Twenty healthy volunteers (18-50 years) received L-CTZ 5mg, CTZ 10 mg, LOR 10 mg, PRM 30 mg and placebo once daily for four days in a five-way, double-blind, crossover study. For each treatment condition, subjects were assessed using a psychometric test system and a pinprick weal and flare response to 100 mg/ml histamine solution at baseline and at 1, 2, 3 ,4, 6, 8, 10 and 122 hours post-dose on days 1 and 4. The psychometrics comprised critical flicker fusion (CFF), choice reaction time (CRT), a continuous tracking task (CTT) and subjective rating scales for sedation (LARS). On days 2 and 3, subjects took their medication at pre-designated times while out of the unit. RESULTS: The verum (PRM) established the sensitivity of the test battery: a significant overall reduction in CFF thresholds on both days 1 and 4 (p < 0.05); an overall significant increase (impairment) in recognition, motor and total reaction times on day 1 (p < 0.05); a significant impairment of both the tracking accuracy and reaction time aspects of the CTT task on day 1 (p < 0.005) and significantly higher ratings of subjective sedation on day 1 (p < 0.05). L-CTZ, CTZ and LOR were not distinguishable from placebo in any of the objective and subjective tests at any time point on either day 1 or day 4. With regards to the peripheral inhibitory effects, L-CTZ inhibited both the weal and flare reaction, with maximum inhibition (almost 100%) occurring within two hours of drug ingestion. CTZ also showed evidence of potent peripheral inhibition of histamine, whereas PRM, and especially LOR, showed only a weak weal and flare reaction which had completely attenuated at day 4. CONCLUSIONS: In a study where the psychometric assessments were shown to be sensitive to impairment, L-CTZ 5 mg was found following both initial and repeated doses, but also to be demonstrably free from disruptive and sedative effects on objective measures of psychomotor and cognitive function. Similarly, CTZ showed evidence of pronounced antihistaminic activity and significantly reduced weal and flare scores after both acute and repeated doses, again without evidence of cognitive or psychomotor impairment. LOR also was non-sedative but the antihistaminic reaction was demonstrably weak.

Adult↗
PubMed2001

Effect of patient education on adherence to drug treatment for rheumatoid arthritis: a randomised controlled trial.

OBJECTIVE: To determine whether a patient education programme (PE) would improve rates of adherence to a slow acting antirheumatic drug and to assess any subsequent effect on patient outcome. METHODS: A randomly controlled study comprising 100 patients with rheumatoid arthritis (49 control CG; 51 experimental EG) requiring D-penicillamine (DPA). The same practitioner saw patients on seven occasions, for the same length of time. The EG received 7 x 30 minute one to one sessions of PE, while the CG received standard management. The primary measure of adherence was a pharmacological marker (phenobarbitone) encapsulated with the DPA assayed at monthly intervals for six months. Plasma viscosity (PV), C reactive protein, articular index, morning stiffness, and pain score were used to assess outcome. RESULTS: 454 blood samples were collected and assayed and the pharmacological marker showed the EG to be significantly more adherent on more occasions than the CG (p<0.05). Patterns of adherence over time showed that at 12 weeks 86% (38/44) of those in the EG compared with 64% (29/45) of the CG remained adherent (p=0.01). These trends continued and by the end of the study 85% (29/34) of the EG compared with 55% (23/42) of the CG were taking their DPA as prescribed. Fifteen patients (12 from the EG) experienced side effects requiring study withdrawal and 14 patients requested study withdrawal (two from the EG). On study entry patients in the CG had significantly higher levels of PV than the EG and this remained so throughout the research. However, on completion, the health status of patients in both groups had improved significantly (p<0.01). CONCLUSIONS: PE significantly increased adherence to DPA and its effects persisted over a period of six months. No additional clinical benefit was detected in the EG in comparison with the CG.

Adult↗
PubMed2001

Using cognitive work analysis to design clinical displays.

In today's ICUs clinicians routinely integrate huge numbers of discrete data points to arrive at a coherent picture of their patients' status. Often the clinician must obtain those data elements from many devices, which makes the problem more difficult. Because presenting data visually amplifies cognition by capitalizing on well-known human perceptual capabilities, it is not surprising that a growing body of research is directed at the effective presentation of visual information in clinical displays. However, developing clinical displays that effectively support clinicians' integration and understanding of many discrete data elements in complex, high technology work domains such as ICUs remains elusive. It may be that traditional analysis and design methods simply are inadequate for this kind of complex environment. Vicente has described a new methodology, called "cognitive work analysis" (CWA), which is targeted at the analysis of complex work domains. The analysis differs from traditional analytic methods in significant ways, particularly in its primary focus on analysis of the work domain, but also in its prescription for explicitly collecting information at five levels (the work domain, diagnostic and treatment tasks, diagnostic strategies, socio-organizational, and clinician skills) that place constraints on the ultimate display design. In this model, the order of data collection is also crucial. Because the work domain constraints tend to be the most permanent, they are likely to have the most impact on design, and so analysis starts there. As the analysis proceeds through the subsequent levels, additional design constraints are identified. We recently used CWA to analyze the information needs for interactive graphical displays that will integrate and represent data in structures that help clinicians visualize a patient's physiological status. We found that the analysis was an effective way to identify information needs at multiple levels. Based on our experience, CWA is a generic methodology that is highly applicable to medical informatics.

Algorithms↗
PubMed2001

Genetic predisposition and pathogenetic mechanisms of interstitial lung diseases of unknown origin.

Understanding of the cellular and cytokine interactions associated with inflammation and fibrosis in interstitial lung diseases (ILDs) has increased substantially during the past few years. Presently, many agents are known to have the ability to induce ILDs, although only a small percentage of exposed individuals will develop the disease. In addition, the majority of ILDs are of unknown origin and many are labelled "idiopathic". Therefore, host susceptibility, genetic factors and, possibly, environmental cofactors may be important for the clinical expression of ILDs. The present review reports evidence of the genetic predisposition to develop ILDs of unknown origin, more specifically sarcoidosis, idiopathic pulmonary fibrosis (IPF), lymphangioleio-myomatosis and ILDs, in systemic sclerosis. For instance, for sarcoidosis and IPF several histocompatibility antigens have been associated with the development and/or the clinical presentation of the disease. Furthermore, there are also several types of ILD that are associated with inherited disorders, of which the tuberous sclerosis complex is only one example. This clearly indicates that pulmonary fibrosis can be influenced by genetic factors. Familial occurrence of sarcoidosis and IPF is also well known, although the exact modes of inheritance are debatable. Several studies have shown that extrinsic factors, such as single or multiple fibrosing agents, probably contribute to the development of clinical ILDs of unknown origin. It is probable that some of these studies deal with patients who do not have classical IPF, as recently defined by the American Thoracic Society (ATS)/European Respiratory Society (ERS) consensus. Therefore, the true role of these extrinsic factors in the development of IPF, or even sarcoidosis, remains speculative. With the help of animal studies and, more specifically, by using knock-out mice, it may be possible in the near future to unravel at least some of the genes that are responsible for the increased susceptibility of the development of interstitial lung diseases.

Animals↗
PubMed2001

Evaluating the UMLS as a source of lexical knowledge for medical language processing.

Medical language processing (MLP) systems rely on specialized lexicons in order to recognize, classify, and normalize medical terminology, and the performance of an MLP system is dependent on the coverage and quality of such lexicons. However, the acquisition of lexical knowledge is expensive and time-consuming. The UMLS is a comprehensive resource that can be used to acquire lexical knowledge needed for medical language processing. This paper describes methods that use these resources to automatically create lexical entries and generate two lexicons. The first lexicon was created primarily using the UMLS, whereas the second was created by supplementing the lexicon of an existing MLP system called MedLEE with entries based on the UMLS. We subsequently carried out a study, which is the primary focus of this paper, using MedLEE with each of the two lexicons and also the current MedLEE lexicon to measure performance. Overall accuracy, sensitivity, and specificity using the lexicon primarily based on the UMLS were.86,.60, and.96 respectively. Those measures using the MedLEE lexicon alone were.93,.81, and.93, which was significantly better except for specificity; performance using the supplemental lexicon was exactly the same as performance using solely the MedLEE lexicon.

Natural Language Processing↗
PubMed2001

Data collection and IT.

Nurses must ensure that the data they routinely collect on their nursing activities is helping to improve patient care and is not just a paper--or electronic--exercise.

Data Collection↗
PubMed2001

Direct action.

Explore the source record for details and available documents.

Counseling↗
PubMed2001

Support network.

Explore the source record for details and available documents.

Algorithms↗
PubMed2001

Planning for practice.

The national information strategy for the NHS was published three years ago. What progress has been made on turning it into operational reality across the country?

Diffusion of Innovation↗
PubMed2000

Sequence and analysis of chromosome 5 of the plant Arabidopsis thaliana.

The genome of the model plant Arabidopsis thaliana has been sequenced by an international collaboration, The Arabidopsis Genome Initiative. Here we report the complete sequence of chromosome 5. This chromosome is 26 megabases long; it is the second largest Arabidopsis chromosome and represents 21% of the sequenced regions of the genome. The sequence of chromosomes 2 and 4 have been reported previously and that of chromosomes 1 and 3, together with an analysis of the complete genome sequence, are reported in this issue. Analysis of the sequence of chromosome 5 yields further insights into centromere structure and the sequence determinants of heterochromatin condensation. The 5,874 genes encoded on chromosome 5 reveal several new functions in plants, and the patterns of gene organization provide insights into the mechanisms and extent of genome evolution in plants.

Animals↗