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N Robertson

Publications and source records attributed to N Robertson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Experience using radio frequency laptops to access the electronic medical record in exam rooms.

Kaiser Permanente, Northwest, evaluated the use of laptop computers to access our existing comprehensive Electronic Medical Record in exam rooms via a wireless radiofrequency (RF) network. Eleven of 22 clinicians who were offered the laptops successfully adopted their use in the exam room. These clinicians were able to increase their exam room time with the patient by almost 4 minutes (25%), apparently without lengthening their overall work day. Patient response to exam room computing was overwhelmingly positive. The RF network response time was similar to the hardwired network. Problems cited by some laptop users and many of the eleven non-adopters included battery issues, different equipment layout and function, and inadequate training. IT support needs for the RF laptops were two to four times greater than for hardwired desktops. Addressing the reliability and training issues should increase clinician acceptance, making a successful general roll-out for exam room computing more likely.

Computer Communication Networks↗
PubMed1998

Functional characterization of the protease of human endogenous retrovirus, K10: can it complement HIV-1 protease?

To investigate the biochemical properties of the protease encoded by the human endogenous retrovirus, K10 (HERV-K), 213 amino acids of the 3'-end of the HERV-K protease (PR) open reading frame were expressed in Escherichia coli. Autocatalytic cleavage of the expressed polypeptide resulted in an 18.2 kDa protein which was shown to be proteolytically active against a fluorogenic peptide used as a substrate for HIV-1 protease. On the basis of sequence homology and molecular modeling, the 106 N-terminal amino acids of HERV-K PR were predicted to comprise a retroviral protease core domain. An 11.6 kDa protein corresponding to this region was expressed and shown to be a fully functional enzyme. The 11.6 kDa domain of HERV-K PR is unusually stable over a wide pH range, exhibits optimal catalytic activity between pH 4.0 and 5.0, and exists as a dimer at pH 7.0 with a Kd of 50 microM. Like HIV-1 PR, the HERV-K PR core domain is activated by high salt concentrations and processes HIV-1 matrix-capsid polyprotein at the authentic HIV-1 PR recognition site. However, both the 18.2 and 11.6 kDa forms of HERV-K PR were highly resistant to a number of clinically useful HIV-1 PR inhibitors, including ritonavir, indinavir, and saquinavir. This raises the possibility that HERV-K PR may complement HIV-1 PR during infection, and could have implications for protease inhibitor therapy and drug resistance.

Amino Acid Sequence↗
PubMed1998

Indolequinone antitumor agents: reductive activation and elimination from (5-methoxy-1-methyl-4,7-dioxoindol-3-yl)methyl derivatives and hypoxia-selective cytotoxicity in vitro.

A series of indolequinones bearing a variety of leaving groups at the (indol-3-yl)methyl position was synthesized by functionalization of the corresponding 3-(hydroxymethyl)indolequinone, and the resulting compounds were evaluated in vitro as bioreductively activated cytotoxins. The elimination of a range of functional groups-carboxylate, phenol, and thiol-was demonstrated upon reductive activation under both chemical and quantitative radiolytic conditions. Only those compounds which eliminated such groups under both sets of conditions exhibited significant hypoxia selectivity, with anoxic:oxic toxicity ratios in the range 10-200. With the exception of the 3-hydroxymethyl derivative, radiolytic generation of semiquinone radicals and HPLC analysis indicated that efficient elimination of the leaving group occurred following one-electron reduction of the parent compound. The active species in leaving group elimination was predominantly the hydroquinone rather than the semiquinone radical. The resulting iminium derivative acted as an alkylating agent and was efficiently trapped by added thiol following chemical reduction and by either water or 2-propanol following radiolytic reduction. A chain reaction in the radical-initiated reduction of these indolequinones (not seen in a simpler benzoquinone) in the presence of a hydrogen donor (2-propanol) was observed. Compounds that were unsubstituted at C-2 were found to be up to 300 times more potent as cytotoxins than their 2-alkyl-substituted analogues in V79-379A cells, but with lower hypoxic cytotoxicity ratios.

Animals↗
PubMed1998

The genetics of multiple sclerosis: principles, background and updated results of the United Kingdom systematic genome screen.

Genetic susceptibility to multiple sclerosis is implicated on the basis of classical family studies and phenotype analyses. The only reproducible legacy from the candidate gene approach has been the discovery of population associations with alleles of the major histocompatibility complex. Systematic genome scanning has since been applied using a panel of anonymous markers to identify areas of linkage in co-affected siblings. Here, we describe the principles of genome screening and update the UK survey of multiple sclerosis. This identified 20 regions of potential interest, but in none was there unequivocal linkage. In theory, attempting to replicate these findings in a second set of sibling pair families is the most appropriate way to distinguish true from false positives, but unfortunately the number of families required to do this reliably is prohibitively large. We used three approaches to increase the definition achieved by the screen: (i) the number of sibling pairs typed in an identified region of potential linkage was extended; (ii) the information extraction was increased in an identified region; and (iii) a search was made for missed regions of potential linkage. Each of these approaches has considerable limitations. A chromosome-by-chromosome account is given to direct future searches. Although an additional marker placed distal to the 'hit' on chromosome 14q increased linkage in this area, and typing extra sibling pairs increased linkage on chromosomes 6p and 17q, evidence for linkage was more commonly reduced and no additional regions of interest were found. A further refinement of the genome screen was undertaken by conditioning for the presence of HLA-DR15. This produced a surprising degree of segregation among the regions of interest, which divided into two distinct groups depending on DR15 sharing: the DR15-sharing cohort comprised loci on chromosomal areas 1p, 17q and X; and the DR15-non-sharing cohort was made up of loci on 1cen, 3p, 7p, 14q and 22q. This result further highlights the genetic complexity of multiple sclerosis. What can now be inferred is that a gene of major effect is excluded from 95% of the genome and one with a moderate role from 65%, whereas genes which make a very small biological contribution cannot be discounted from any region. The available results suggest that multiple sclerosis depends on independent or epistatic effects of several genes each with small individual effects, rather than a very few genes of major biological importance.

Genetic Linkage↗
PubMed1998

Introducing a quality improvement programme to primary healthcare teams.

OBJECTIVES: To evaluate a programme in which quality improvement was facilitated, based on principles of total quality management, in primary healthcare teams, and to determine its feasibility, acceptability, effectiveness, and the duration of its effect. METHOD: Primary healthcare teams in Leicestershire (n = 147) were invited to take part in the facilitated programme. The programme comprised seven team meetings, led by a researcher, plus up to two facilitated meetings of quality improvement subgroups, appointed by each team to consider specific quality issues. OUTCOME MEASURES: To assess the effect and feasibility of the programme on improving the quality of care provided, the individual quality improvement projects undertaken by the teams were documented and opportunities for improvement were noted at each session by the facilitator. The programme's acceptability was assessed with questionnaires issued in the final session to each participant. To assess the long term impact on teams, interviews with team members were conducted 3 years after the programme ended. RESULTS: 10 of the 27 teams that initially expressed interest in the programme agreed to take part, and six started the programme. Of these, five completed their quality improvement projects and used several different quality tools, and three completed all seven sessions of the programme. The programme was assessed as appropriate and acceptable by the participants. Three years later, the changes made during the programme were still in place in three of the six teams. Four teams had decided to undertake the local quality monitoring programme, resourced and supported by the Health Authority. CONCLUSIONS: The facilitated programme was feasible, acceptable, and effective for a few primary healthcare teams. The outcomes of the programme can be sustained. Research is needed on the characteristics of teams likely to be successful in the introduction and maintenance of quality improvement programmes.

Decision Making, Organizational↗
PubMed1998

11Beta-hydroxysteroid dehydrogenase, mineralocorticoid receptor, and thiazide-sensitive Na-Cl cotransporter expression by distal tubules.

Mineralocorticoid hormones regulate salt transport along the distal nephron by binding to intracellular receptors and activating gene transcription. Previous experiments showed that systemic aldosterone infusions stimulate thiazide-sensitive Na and Cl transport by distal convoluted tubule (DCT) cells; this effect could have been direct or secondary to systemic hormonal effects. Aldosterone target tissues express both mineralocorticoid receptors and the metabolic enzyme 11beta-hydroxysteroid dehydrogenase type 2. Mineralocorticoid receptors have been localized to the DCT in some experiments, but not in others. Expression of 11beta-hydroxysteroid dehydrogenase type 2 by DCT cells has not been investigated. The present experiments were designed to test the hypothesis that rat DCT cells are targets of aldosterone action. Patterns of mineralocorticoid receptor, 11beta-hydroxysteroid dehydrogenase, thiazide-sensitive Na-Cl cotransporter, and Na/Ca exchanger expression along the distal tubule were examined. A polyclonal antibody was generated to localize the thiazide-sensitive Na-Cl cotransporter. Thiazide-sensitive Na-Cl cotransporter and 11beta-hydroxysteroid dehydrogenase expression were examined using both in situ hybridization and immunocytochemistry; Na/Ca exchanger and mineralocorticoid receptor expression were examined by immunocytochemistry. The results indicate that 11beta-hydroxysteroid dehydrogenase is expressed by DCT cells, as well as connecting tubule cells and principal cells of the collecting duct; expression levels are low near the junction with the thick ascending limb and rise near the transition to the connecting tubule. Mineralocorticoid receptors are expressed by DCT cells, as well as along the thick ascending limb, connecting tubule, and collecting duct. The results indicate that components of the mineralocorticoid receptor system are expressed by DCT cells, suggesting that these cells are targets of aldosterone action.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1998

5-substituted analogues of 3-hydroxymethyl-5-aziridinyl-1-methyl-2-[1H-indole-4,7-dione]prop-2-en- 1-ol (EO9, NSC 382459) and their regioisomers as hypoxia-selective agents: structure-cytotoxicity in vitro.

A series of regioisomeric analogues of 3-hydroxymethyl-5-aziridinyl-1-methyl-2-[1H-indole-4,7-dione]prop-2-en-1 -ol (EO9, NSC 382459) with the hydroxymethyl and hydroxypropenyl substituents situated at either the 2- or the 3-position of the indole ring were synthesized. The compound lacking the 2-hydroxypropenyl substituent (31) had similar properties to EO9 under both aerobic and hypoxic conditions against V79 cells and was more potent against a human tumour cell line (A549) than EO9. It was reduced by human DT-diaphorase (DTD) at more than double the rate of EO9, thus implicating the importance of the enzyme activation step. Compound 16 (lacking the 3-hydroxymethyl substituent) was a better substrate for human DTD than EO9, yet exhibited lesser toxicity under both aerobic and hypoxic conditions. The toxicity generated by 16 was attributed to the 5-aziridinyl moiety and suggests a greater contribution from the 3-substituent over the 2-substituent. The toxicity of EO9 was attributed to a combination of the aziridinyl group and the leaving group properties of the 3-hydroxymethyl substituent. In general, compounds with a 5-methylaziridinyl moiety, such as EO8, exhibited substantially better hypoxia-selectivity due to much slower reduction by DTD (20-fold), thus reducing aerobic potency. All compounds had similar electron affinities, as indicated by their one-electron reduction potentials.

Aerobiosis↗
PubMed1998

Targeting hypoxia with a new generation of indolequinones.

The indolequinone class of bioreductive alkylating agents has been developed to effectively target the hypoxic cell population of the tumour. The mechanism of activation of these prodrugs relies initially on the reduction of the p-quinonoid moiety utilizing reductive enzymes to form electrophilic sites which can be attacked by DNA to promote cell kill. Minor structural changes of the indole 'nucleus' may result in substantial favourable pharmacological and physiological changes. Investigation of the mode of action of these compounds has resulted in the use of novel indolequinones as 'trigger' molecules that can efficiently release secondary agents into the hypoxic site of action.

Antineoplastic Agents↗
PubMed1996

The Ced-3/interleukin 1beta converting enzyme-like homolog Mch6 and the lamin-cleaving enzyme Mch2alpha are substrates for the apoptotic mediator CPP32.

Recent evidence suggests that CPP32 is an essential component of an aspartate-specific cysteine protease (ASCP) cascade responsible for apoptosis execution in mammalian cells. Activation of CPP32 could lead to activation of other downstream ASCPs, resulting in late morphological changes such as lamin cleavage and DNA fragmentation, observed in cells undergoing apoptosis. Here we describe the identification and cloning of a novel human ASCP named Mch6 from Jurkat T lymphocytes. We demonstrate that the pro-enzymes of Mch6 and the lamin-cleaving enzyme Mch2alpha are substrates for mature CPP32. Site-directed mutagenesis revealed that CPP32 processes pro-Mch6 preferentially at Asp330 to generate two subunits of molecular masses 37 kDa (p37) and 10 kDa (p10). However, CPP32 processes pro-Mch2alpha at three aspartate processing sites (Asp23, Asp179, and Asp193) to produce the large (p18) and small (p11) subunits of the mature Mch2alpha enzyme. The CPP32-processed Mch2alpha is capable of cleaving the VEIDN lamin cleavage site, indicating that CPP32 can, in fact, activate pro-Mch2alpha. Granzyme B at a concentration that allows processing and activation of CPP32 failed to process pro-Mch2alpha. However, incubation of pro-Mch2alpha with granzyme B in the presence of a cellular extract containing pro-CPP32 resulted in activation of pro-CPP32 and subsequent processing of pro-Mch2alpha. Interestingly, granzyme B can also process pro-Mch6 but at a site N-terminal to that cleaved by CPP32. These data suggest that Mch2alpha and Mch6 are downstream proteases activated in CPP32- and granzyme B-mediated apoptosis. This is the first demonstration of a protease cascade involving granzyme B, CPP32, Mch2alpha, and Mch6 and evidence that the lamin-cleaving enzyme Mch2 is a target of mature CPP32.

Amino Acid Sequence↗
PubMed1996

Sequence of mitochondrial DNA in patients with multiple sclerosis.

The excess female transmission of multiple sclerosis (MS) and the observation of an MS-like illness in patients with Leber's hereditary optic neuropathy who carry a mitochondrial DNA mutation may indicate that mitochondrial genes contribute to the genetic susceptibility to MS. We sequenced the protein- and RNA-coding sequences of 9 patients with MS who had a family history of MS consistent with maternal transmission. Four base-pair (bp) changes of particular interest were identified. Those at bp 4216 and 4917 may play a role in the etiology of Leber's hereditary optic neuropathy. Two others, at bp 11447 and 14766, were found in all MS patients sequenced. Restriction enzyme analysis used to screen 175 unrelated MS patients and 233 healthy control subjects showed that each of these changes was present in MS patients at a similar frequency to control subjects. The 4216 and 4917 changes were at a higher frequency in north European control subjects than previously documented. We conclude that variation in mitochondrial DNA is unlikely to contribute to susceptibility to MS. The etiology of the overlap between Leber's hereditary optic neuropathy and MS remains unexplained.

Cytochromes↗
PubMed1996

A genome screen in multiple sclerosis reveals susceptibility loci on chromosome 6p21 and 17q22.

The population prevalence of multiple sclerosis is 0.1%; however, the risk of the disease in the siblings of affected individuals is very much higher at 3-5%. The importance of genetic factors in accounting for this increased risk is confirmed by the results of twin and adoption studies. Despite the evidence for a strong genetic effect, a weak major histocompatibility complex (MHC) association is the only consistently observed feature in the genetics of multiple sclerosis. Other candidates have been proposed, including genes encoding the immunoglobulin heavy chain, T cell receptor beta chain and APOC2, but none has yet been confirmed. Evidence for linkage and association to the myelin basic protein gene has been reported in a genetically isolated Finnish population, but it has not been possible to reproduce these results in other populations. We used a two-stage approach to search the human genome for the genes causing susceptibility to multiple sclerosis. Two principal regions of linkage are identified, chromosomes 17q22 and 6p21 (MHC). Our results are compatible with genetic models involving epistatic interaction between these and several additional genes.

Chromosome Mapping↗
PubMed1996

Multiple sclerosis in south Cambridgeshire: incidence and prevalence based on a district register.

STUDY OBJECTIVE: To establish an updated prevalence and incidence figure for multiple sclerosis on 1 July 1993, to determine the fate of the 374 patients prevalent in 1990, and to establish the origin of incident patients. DESIGN: Case ascertainment was from several sources including departmental records, local branches of the Multiple Sclerosis Society, general practitioners, nursing homes, and residential facilities for the disabled. Data collection was by personal interview using a standardised questionnaire and by retrospective analysis of departmental case notes. A prospective incidence register of newly diagnosed patents was maintained from 1990. SETTING: The Cambridge Health District of East Anglia covering 340,910 hectares in area and a population of 290,700. PATIENTS: Altogether 441 patients prevalent on 1 July 1993 were identified, of whom 328 were contacted so that clinical data could be collected. Seventy patients (16%) either declined to take part or access was denied by their general practitioner; 8 (2%) had died; and 35 (8%) were too ill or failed to respond to several requests for contact. MAIN RESULTS: A comprehensive re-evaluation of the south Cambridgeshire multiple sclerosis register revealed a prevalence of 441/290,700 population (152/10(5)) for all disease classifications on 1 July 1993. This represented an increase of 18% from 1990 and was a result of 138 additions and 71 deletions from the original list of 374 patients. The sex ratio of prevalent patients was 2.6 F:M, the mean age at disease onset was 31.7 years, and the mean age was 49 years. Mortality for 1990-93 was 3.3/10(5)/year and prospective maintenance of an incidence register recorded 96 new diagnoses for all classifications of multiple sclerosis over the five year period 1990-94 (6.6/10(5)/year). CONCLUSIONS: The increase in prevalence mainly resulted from improved case ascertainment identifying a further 58 patients who had been prevalent in 1990. Comparisons with other serial studies within the United Kingdom show similarities in proportional increase with successive studies indicating that serial survey may in part account for the observed latitudinal gradient within the United Kingdom. However, the observed prevalence (152/10(5)) in this second survey still falls short of the figure estimated from incidence and mortality data (186/10(5)).

Adolescent↗
PubMed1995

Audit in general practice: factors influencing participation.

OBJECTIVE: To identify the factors influencing participation in a single topic audit initiated by a medical audit advisory group. DESIGN: Interview and questionnaire survey of general practitioners who had been invited to take part in an audit of vitamin B-12. SETTING: All 147 general practices in Leicestershire. MAIN OUTCOME MEASURES: Aspects of structure, attitude, and behaviour that influenced participation or non-participation. RESULTS: 75 practices completed the audit, 49 withdrew after initial agreement, and 23 refused to take part at the outset. Participants were more likely than those who refused to view the advisory group as useful or a threat and to have positive thoughts about audit but less likely to have previously undertaken audit entailing implementation of change. Participants were more likely than those who withdrew to have positive thoughts about audit and to have discussed whether to take part within the practice but were less likely to view the advisory group as useful. The most common reason given for withdrawal was lack of time. CONCLUSIONS: Participation was influenced by attitudes towards audit in general and the advisory group in particular and by aspects of behaviour such as communication within the practice. Practical support and resources may help some practices undertake audit, but advisory groups must also deal with attitudes and unsatisfactory communication in practice teams.

Anemia, Pernicious↗
PubMed1995

Susceptibility to multiple sclerosis and the immunoglobulin heavy chain variable region.

A haplotype marker consisting of three biallelic restriction fragment length polymorphism (RFLP) loci from the VH-2 variable gene family was examined in 124 families with sibling pairs concordant for multiple sclerosis, 178 unrelated patients and 159 unaffected controls to investigate the role of the immunoglobulin heavy chain gene cluster in susceptibility to multiple sclerosis. Evidence for linkage was assessed using the affected sibling pair method of identity by descent, modified to allow for haplotype sharing on a probabilistic basis in families where haplotypes could not be assigned with certainty. The estimated probabilities of affected siblings sharing 0, 1 or 2 haplotypes were Z0 = 0.20, Z1 = 0.45, Z2 = 0.35. This deviation from the expected sharing probabilities of Z0 = 0.25, Z1 = 0.5, Z2 = 0.25 provides evidence for weak linkage (P < 0.05; equivalent to a lod score of 0.84); however, no significant allelic or haplotypic association was observed. Linkage without a population association suggests that a gene encoded on 14q confers susceptibility to multiple sclerosis, although this is not any of the existing VH-2 polymorphisms.

Alleles↗
PubMed1995

Sequence of the human homologue of a mitochondrially encoded murine transplantation antigen in patients with multiple sclerosis.

There is some evidence that mitochondrial genes may contribute to susceptibility to multiple sclerosis (MS), and a mitochondrial DNA-encoded peptide, the N-terminal portion of NADH-dehydrogenase subunit 1, acts as a transplantation antigen in mice. We have analysed the DNA sequence of the corresponding region of human mitochondrial DNA in 87 patients with MS, 10 with Leber's hereditary optic neuropathy in association with an MS-like illness, and 31 control subjects. This sequence appears to be highly conserved. Only three base pair changes were identified, each being found once only in one control and two patients, and these are likely to be harmless polymorphisms. There is thus no evidence that polymorphism in this region contributes to genetic susceptibility in MS.

Animals↗
PubMed1995

Multiple sclerosis and the HLA-D region: linkage and association studies.

Inheritance patterns of multiple sclerosis (MS) in multiplex families suggest a complex aetiology involving environmental and genetically determined components. The association between the HLA class II DR15, DQ6, Dw2 haplotype and MS has been well documented in patients with ancestral origins in Northern Europe. Conversely, linkage analysis of this region in multiplex families, derived from a population base, has generated negative results. Thus, given the Dw2 specificity association, evidence implicating this locus in disease susceptibility appears contradictory. We have collected and determined the HLA-DR and -DQ haplotypes of 115 sibling pairs with multiple sclerosis, and confirm a significant association with the Dw2-associated haplotype, both in index cases and their affected siblings compared with controls. However, using a sibling pair linkage analysis that restricts haplotype sharing probabilities to defined genetic models, we have not observed linkage of this region to susceptibility in MS. We discuss the basis for association and linkage and conclude that the DR15, DQ6, Dw2 haplotype does represent a susceptibility locus but its contribution to the pathogenesis is small; although it may interact epistatically with other susceptibility genes, this haplotype is not necessary for disease expression.

Adult↗