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Biomedical subjects

J Richardson

Publications and source records attributed to J Richardson.

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

Complementary therapies: what is the evidence for their use?

Complementary therapies are being increasingly used by patients and health-care professionals, but often with little awareness of the evidence for their use. The Internet offers a valuable and easy-to-use resource for assessing a growing amount of published information. Nurses need to be aware of a treatment's effectiveness and warn patients of potential risks or unprofessional claims.

Complementary Therapies↗
PubMed2000

Zinc plays a key role in human and bacterial GTP cyclohydrolase I.

The crystal structure of recombinant human GTP cyclohydrolase I was solved by Patterson search methods by using the coordinates of the Escherichia coli enzyme as a model. The human as well as bacterial enzyme were shown to contain an essential zinc ion coordinated to a His side chain and two thiol groups in each active site of the homodecameric enzymes that had escaped detection during earlier studies of the E. coli enzyme. The zinc ion is proposed to generate a hydroxyl nucleophile for attack of imidazole ring carbon atom eight of the substrate, GTP. It may also be involved in the hydrolytic release of formate from the intermediate, 2-amino-5-formylamino-6-ribosylamino-4(3H)-pyrimidinone 5'-triphosphate, and in the consecutive Amadori rearrangement of the ribosyl moiety.

Amino Acid Sequence↗
PubMed2000

Pneumocystis carinii mutations are associated with duration of sulfa or sulfone prophylaxis exposure in AIDS patients.

This study was conducted to determine whether Pneumocystis carinii dyhydropteroate synthase (DHPS) gene mutations in AIDS patients with P. carinii pneumonia (PCP) are affected by duration of sulfa or sulfone prophylaxis and influence response to sulfa or sulfone therapy. The P. carinii DHPS genes from 97 AIDS patients with PCP between 1991 and 1999 from 4 medical centers were amplified, using polymerase chain reaction (PCR), and sequenced. Mutations were observed in 76% of isolates from patients exposed to sulfa or sulfone prophylaxis compared with 23% of isolates from patients not exposed (P=.001). Duration of prophylaxis increased the risk of mutations (relative risk [RR] for each exposure month, 1.06; P=.02). Twenty-eight percent of patients with mutations failed sulfa or sulfone treatment; mutations increased the risk of sulfa or sulfone treatment failure (RR, 2.1; P=0.01). Thus, an increased duration of sulfa or sulfone prophylaxis increases the chance of developing a P. carinii mutation. The majority of patients with mutations respond to sulfa or sulfone therapy.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Localisation and characterisation of ovine immunglobulin within the sheep scab mite, Psoroptes ovis.

Ovine IgG was detected in homogenates of repeatedly washed Psoroptes ovis. Some of the immunoglobulin in the homogenates was fragmented although the host IgG present in mite washings was largely intact. The host immunoglobulin was immuno-localised to the surface or cytoplasm of the gut cells of feeding stages of freshly harvested P. ovis examined by cryosectioning. A similar distribution of rabbit IgG was detected in P. cuniculi. The IgG demonstrated in the mite gut represented partially digested as well as intact immunoglobulin. The presence of intact host immunoglobulin suggests that P. ovis may be susceptible to vaccination by the gut antigen approach, a method used successfully for blood-feeding ectoparasites like Boophilus microplus.

Animals↗
PubMed2000

Are amplitude and duration of anticipatory postural adjustments identically scaled to focal movement parameters in humans?

Anticipatory postural adjustments (APA), are known to precede the onset of voluntary movement. The aim of this study was to determine whether APA amplitude and duration are programmed identically according to the voluntary movement parameters. Subjects performed shoulder flexions at maximal and sub-maximal velocities, with and without an additional inertial load. APA amplitude and duration were plotted against kinetic energy and work of the forthcoming voluntary limb movement and showed a significant linear relation. When APA duration was plotted against mechanical work, two distinct APA duration values corresponded to a given value of work depending on the weight of the load, but this was not the case for APA amplitude. It is suggested that the APA amplitude and duration are scaled according to the same movement parameters, but not in the same way, APA duration being additionally sensitive to the postural effect which results from an additional weight.

Adult↗
PubMed2000

Societal value, the person trade-off, and the dilemma of whose values to measure for cost-effectiveness analysis.

In a previous paper, it was argued that Societal Value measurement through person trade-off (PTO) elicitation offers a way to include the values of both general public and patients into cost-effectiveness analysis (CEA). It was said that patients' values could be used to estimate the effect that various health care dimensions have on health-related utility and that public values could be used to estimate the Societal Value of these changes in utility. However, this previous proposal still creates opportunities for the public to misvalue the benefit of health care interventions because of bias or misunderstanding about what the health-related utility really is of various illnesses or disabilities. A procedure that combines patient and public values into CEA to partially correct for this bias is suggested in this paper. In addition, it is pointed out that, although Societal Value measurement offers a role for distinctly public preferences in CEA, it still does not answer the question of whose utilities ought to be included in CEA.

Cost-Benefit Analysis↗
PubMed2000

Definition of polymorphic residues on killer Ig-like receptor proteins which contribute to the HLA-C binding site.

Killer cell immunoglobulin-like receptors (KIR) bind HLA class I proteins in an allele- and locus-specific manner. This report describes the use of transfectants expressing recombinant chimeric proteins, comprising the extracellular portions of KIR molecules and the transmembrane and cytoplasmic tails of CD3-zeta, to create an in vitro system in which signaling is readily measured and that preserves the specificity of the KIR / HLA-C interaction. The identity of the amino acid residues on the KIR molecule important for binding to the HLA protein is not well understood; although some KIR2D residues involved in HLA-C recognition have been identified, their relative importance and whether other amino acids contribute to binding was unclear. This novel system was used to study, by site-directed mutagenesis, the role of various amino acids in KIR binding to HLA-C ligand. The data presented here show that while multiple polymorphic residues contribute to the HLA-C binding site on KIR proteins, two clusters of polymorphic residues define the group allotype specificity of HLA-C binding to a KIR2D molecule.

Animals↗
PubMed2000

Do anticipatory postural adjustments occurring in different segments of the postural chain follow the same organisational rule for different task movement velocities, independently of the inertial load value?

Dynamic phenomena, termed anticipatory postural adjustments (APA), are known to precede the onset of voluntary movement. Their anticipatory nature confers a particular status on APAs: as they cannot be triggered reflexly by afferent signals induced by a voluntary movement, it can be asked whether the APA parameters are centrally programmed as a function of some task movement parameters or are only the peripheral consequence of control variables. To this end the present study aims to determine whether the APAs occurring at the different sites of the postural chain yield the same accelerometric patterns and follow the same organisational rules when the task movement velocity changes, independently of the inertial load value. Subjects performed unilateral shoulder flexions at maximal and submaximal velocities, with (IUF) and without (OUF) an additional inertial load. Accelerometers were attached to the wrist and trunk, and on both sides of the body at shank, thigh, hip and shoulder. The results show that: 1) there was evidence of anticipatory acceleration in all segments of the postural chain; 2) each acceleration profile for the anticipatory phase was maintained over different focal movement velocities whether there was an additional load or not; 3) there were significant linear relationships between the amplitude of each segmental anticipatory acceleration and the square of the task movement velocity, the slope of which differs as a function of the inertial load; 4) there were close intersegmental correlations between these anticipatory accelerations which did not depend on the inertial load. In addition the correlation between the lower limbs and the opposite side of the body was positive, suggesting a diagonal postural pattern. A comparison of the present kinematic data with the corresponding EMG data reported in the literature argues in favour of a centrally determined kinematic pattern. It is proposed that the diagonal postural pattern between postural segments be considered as one of the order rules which could simplify the control process of asymmetrical movement. The anticipatory kinematics of each of the body segments would be calibrated with the velocity and the inertial load and scaled to the other segments to counteract the perturbing effect of the asymmetrical focal movement on body balance.

Acceleration↗
PubMed2000

Skin characteristics and risk of superficial spreading and nodular melanoma (United States).

OBJECTIVE: To assess the risk for melanoma associated with moles and pigmentary characteristics. METHODS: Representative melanoma cases (773) among non-Hispanic white residents under age 65 occurring between 1 June 1978 and I December 1983 in Los Angeles County were compared to controls (752) matched to cases by age, sex, race and neighborhood of residence. Factors considered include hair, eye, and skin color; numbers of freckles and moles; and propensity to burn and tan obtained during an in-person interview. RESULTS: Five hundred and fifty-one cases were classified as superficial spreading melanoma (SSM) and 110 as nodular melanoma (NM). For SSM, the important risk determinants were hair and skin color, freckling, and mole prevalence. Light skin and more freckles were found to be more highly associated with SSM for younger compared to older subjects, whereas the associations between SSM and both hair color and moles remained independent of age. NM showed patterns of risk similar to SSM with the exception of skin color. NM showed no evidence of increasing risk with lighter skin, as compared to the strong association seen for SSM. CONCLUSION: Hair and skin color, freckling and, especially, numbers and size of moles are important determinants of melanoma risk.

Adult↗
PubMed2000

Strategic use of familiarity in display-based problem solving.

The authors report 4 experiments that investigated the role of recognition memory and plausibility in a display-based problem-solving task (computer menu search). It was found that both the familiarity of options and their plausibility played a role in determining choices when the correct options could not be recollected. The use of familiarity was adaptive: Participants relied less on familiarity when it was a less valid guide to correct choices. The implications of these findings for theories of problem solving and learning are discussed.

Adolescent↗
PubMed2000

A comparison of agonist-specific coupling of cloned human alpha(2)-adrenoceptor subtypes.

The agonist-specific coupling properties of the three cloned human alpha(2)-adrenoceptor subtypes have been compared, when expressed at similar levels in Chinese hamster ovary (CHO) cell lines, using noradrenaline and (+/-)-meta-octopamine as agonists. Noradrenaline can couple the receptor to both the inhibition and stimulation of forskolin-stimulated cyclic AMP production in all three receptor subtypes, with the relative strength of the coupling to the pathways varying for each of the receptor subtypes. meta-Octopamine selectively couples the alpha(2A)-adrenoceptor only to the inhibition of forskolin-stimulated cyclic AMP production. However, meta-octopamine couples the alpha(2B)- and alpha(2C)-adrenoceptors to both the inhibition and stimulation of forskolin-stimulated cyclic AMP production. The relative potency of meta-octopamine to noradrenaline varies between the different alpha(2)-adrenoceptor subtypes. The effects of meta-octopamine are around two orders of magnitude less potent than those of noradrenaline on both the alpha(2A)- and alpha(2B)-adrenoceptor subtypes. In contrast, in the case of the alpha(2C)-adrenoceptor, meta-octopamine is only one order of magnitude less potent than noradrenaline in the stimulation of forskolin-stimulated cyclic AMP production and, in addition, is equipotent with noradrenaline in the inhibition of forskolin-stimulated cyclic AMP production and has an increased maximal response. This raises the possibility that meta-octopamine may have physiologically important actions via alpha(2C)-adrenoceptors in vivo. The results show that the modulation of cyclic AMP production occurs in both a subtype- and agonist-specific manner for alpha(2A)-adrenoceptors and in a subtype specific manner for alpha(2B)- and alpha(2C)-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed2000

The use of randomized control trials in complementary therapies: exploring the issues.

The current popularity of complementary therapies presents an interesting challenge to nurses and midwives. If they are to deliver such therapies themselves, or support patients in choosing appropriate therapies they will need to consider the professional and legal issues, in particular those regarding safety. Evidence for the effectiveness for complementary therapies is also a requirement in order that their integration into nursing practice can be justified. Purchasers are currently hampered by the lack of credible evidence for effectiveness and until that evidence is provided, access to such therapies through the National Health Service (NHS) will remain limited. The form that evidence should take has led to a lively debate about possible methodological approaches. There appears to be a clash between the medical profession and those working in the field of complementary therapy research, with the medical establishment advocating randomized control trials (RCTs). This contrasts with the view held by some advocates of complementary therapies that the RCT approach is reductionist and not applicable to such approaches. The pivot of the debate on the methodological approaches for evaluating complementary therapies is the contrast of two apparently different and diverse world-views, and the assertion that methods developed in one world-view are not transferable to the other. There is also some confusion within the field of complementary therapy over the applicability of RCTs to therapies such as acupuncture, and the mistaken assumption that trials which include a control group, are also required to be double-blind. This paper is based on the need for good quality evidence of effectiveness in complementary therapy. It will set out the concerns associated with the use of RCTs within complementary therapy, together with the benefits and limitations of this approach. The paper will go on to review research options and propose some suggestions for future methodological approaches.

Complementary Therapies↗