Biomedical subjects

J Walker

Publications and source records attributed to J Walker.

At least 145 records · Page 8Linked to original sources

PubMed1999

The clinical performance of new degree graduates.

Since the transfer of nursing education from hospitals to tertiary institutions, debate regarding the competence of new graduates has continued. To date this issue has not been thoroughly researched. The lack of research related to the competence of degree graduates in New Zealand provided the impetus for this study, which was aimed toward identifying how graduates perceived their clinical performance during their first year of practice. A convenience sample of 30 graduates was surveyed after 3 months and 7 months in practice, using an adapted form of a questionnaire devised by Ryan and Hodson (1992). The results showed that over time, graduates generally required less direction in all areas of clinical competence. After 7 months in practice, the majority of the graduates rated their performance in nursing skills, communication skills, and professionalism at the expected level or above. However, some still required direction with using theory and research in practice, with meeting client's psychosocial needs and with teaching clients. In the leadership competency, after 7 months, most graduates saw themselves functioning at the expected level related to client care and needed less direction in unit management skills. However, many of the unit management skills were rated as 'not applicable' indicating that new graduates are not initially placed in a management role. Implications for nursing education and limitations of the research are discussed.

Clinical Competence↗

PubMed1998

Integrins involved in the adhesion of megakaryocytes to fibronectin and fibrinogen.

We studied integrins involved in the adhesion of resting and activated megakaryocytes (MK) to fibronectin (FN) and fibrinogen (FGN). Guinea pig MK were isolated and in some experiments were activated by thrombin. MK adhering to FN or FGN coated on coverslips were quantitated by a computerized image analysis program. The binding of soluble human FN to MK was detected by Western blotting. Anti-integrin antibodies, disintegrins, and cyclic RGD peptides were used to identify integrins involved in the adhesion of MK to FN or FGN. Resting MK adhered to coverslips with immobilized FN. The adhesion of MK to FN was primarily inhibited by an anti-alpha5 antibody and EMF-10, a distintegrin highly specific for alpha5 beta1. However, the adhesion of MK to FN was not blocked by agents that inhibit alphaIIb beta3, alphav beta3 or alpha4 beta1. A beta1 activating antibody increased the number of MK bound to FN due to the activation of alpha5 beta1. The binding of soluble FN was also primarily inhibited by agents that block alpha5 beta1. Resting MK did not adhere to FGN. However, MK activated by thrombin did adhere to FGN. This binding was mediated by alphaIIb beta3, because binding was inhibited by bitistatin, a disintegrin, and a cyclic RGD peptide that are known to block this integrin. The binding of thrombin-activated MK to FN was mediated by both alpha5 beta1 and alphaIIb beta3 based on the additive effect of agents that inhibit these integrins. The study indicates that resting MK bind to FN but not to FGN and that alpha5 beta1 is the major integrin involved in the binding of MK to FN. Activated MK bind to FGN primarily by alphaIIb beta3. However, the binding of activated MK to FN is due to both alpha5 beta1 and alphaIIb beta3. The demonstration that alpha5 beta1 and that alphaIIb beta3 are involved in MK adhesion indicates that these integrins may have a role in MK maturation and platelet production.

Animals↗

PubMed1998

Sequential source of the M100 exhibits inter-hemispheric asymmetry.

The most prominent auditory evoked field component occurs at about 100 ms latency and is termed the M100. We recorded M100 data from 20 subjects, in both hemispheres. We modeled the generators with a single equivalent current dipole in a 10 ms sliding window from 0 to 245 ms post-stimulus. A residual error curve was plotted, and a search for local minima identified two latencies at about 75 and 100 ms. In the left hemisphere, the early generator was about 6 mm above the later source; in the right hemisphere the early source was about 3 mm above the later, and 11 mm posterior. The M100 is a compound source, and the model may provide additional information in cases with reported laterality differences.

Acoustic Stimulation↗

PubMed1998

Integrins and development: how might these receptors regulate differentiation of the lens.

Integrins transduce both internal signals and signals from the matrix. These interactions between integrins, their extracellular matrix ligands, and their cytoskeletal partners play an important role in the regulation of cellular differentiation. We have shown them to be important in lens cell differentiation. In the lens capsule there is a compartmentalization of matrix components with fibronectin, primarily localized to the anterior capsule, and tenascin in the posterior capsule. Integrins are developmentally regulated in the lens. alpha 5 beta 1 integrin, like fibronectin, is primarily associated with the lens epithelial cells, where together they are likely to be important in regulation of adhesion and proliferation. alpha 6A beta 1, the integrin laminin receptor, is expressed at its highest levels in the equatorial epithelium and the peripheral fiber cells, both migratory populations. Because laminin is uniformly distributed in the lens capsule, such changes in alpha 6A integrin expression are likely critical to the cell's ability to regulate its response to laminin in the matrix. The organization of cytoskeletal molecules associated with the integrin cytoplasmic face also changes with development. In the epithelial regions of the lens, where the initiation of lens cell differentiation occurs, expression of the cytoskeletal proteins involved in cell-substrate interactions, talin, alpha-actinin, and the signaling proteins, are high. In the fiber cell region of the lens, where the cells establish stable cell-cell contacts, vinculin predominates and becomes highly associated with the cytoskeletal fraction. The role of integrins in lens development is not only regulated by changes in the expression of different integrin receptors but is also closely correlated with the expression and organization of the molecules with which they associate.

Animals↗

PubMed1998

The primitive protozoon Trichomonas vaginalis contains two methionine gamma-lyase genes that encode members of the gamma-family of pyridoxal 5'-phosphate-dependent enzymes.

Methionine gamma-lyase, the enzyme that catalyzes the breakdown of methionine by an alpha,gamma-elimination reaction and is a member of the gamma-family of pyridoxal 5'-phosphate-dependent enzymes, is present in high activity in the primitive protozoan parasite Trichomonas vaginalis but is absent from mammals. Two genes, mgl1 and mgl2, encoding methionine gamma-lyase, have now been isolated from T. vaginalis. They are both single copy, encode predicted proteins (MGL1 and MGL2) of 43 kDa, have 69% sequence identity with each other, and show a high degree of sequence identity to methionine gamma-lyase from Pseudomonas putida (44%) and other related pyridoxal 5'-phosphate-dependent enzymes such as human cystathionine gamma-lyase (42%) and Escherichia coli cystathionine beta-lyase (30%). mgl1 and mgl2 have been expressed in E. coli as a fusion with a six-histidine tag and the recombinant proteins (rMGL1 and rMGL2) purified by metal-chelate affinity chromatography. rMGL1 and rMGL2 were found to have high activity toward methionine (10.4 and 0.67 mumol/min/mg of protein, respectively), homocysteine (370 and 128 mumol/min/mg of protein), cysteine (6.02 and 1.06 mumol/min/mg of protein), and O-acetylserine (3.74 and 1.51 mumol/min/mg of protein), but to be inactive toward cystathionine. Site-directed mutagenesis of an active site cysteine (C113G for MGL1 and C116G for MGL2) reduced the activity of the recombinant enzymes toward both methionine and homocysteine by approximately 80% (rMGL1) and 90% (rMGL2). In contrast, the activity of mutated rMGL2 toward cysteine and O-acetylserine was increased (to 214 and 142%, respectively), whereas that of mutated rMGL1 was reduced to 39 and 49%, respectively. These findings demonstrate the importance of this cysteine residue in the alpha,beta-elimination and alpha, gamma-elimination reactions catalyzed by trichomonad methionine gamma-lyase.

Amino Acid Sequence↗

PubMed1998

Summary of workshop findings for antibodies reacting with porcine T-cells and activation antigens: results from the Second International Swine CD Workshop.

After initial evaluation of the 176 new and 19 control monoclonal antibodies (mAb) submitted to the Second International Swine CD Workshop, 57 were assigned to the T-cell/activation marker subgroup. These 57 mAb were further analyzed using flow cytometry on whole blood lymphocytes, splenocytes, Peyer's patch lymphocytes, in vitro cell lines, broncho-alveolar lavage cells, Con A and PHA blasts, fetal cell populations, and by 2-color flow cytometry against mAb to porcine CD2, CD4, and CD8. Finally, the molecular weights of the target antigens were characterized when possible. As a result of these analyses, 23 mAb were distributed into 7 CD clusters. Newly confirmed mAb assignments included: two CD2; one CD4; two CD5; one wCD6; and one wCD25. Three new mAb were found that reacted with wCD8, one of which defined a new epitope, wCD8c. For the first time, mAb against porcine CD3 were identified, including 6 mAb that reacted with three different epitopes. Several new mAb reacted with antigens whose expression varied depending on the activation state of the test cell. These will require further characterization in order to assign a CD number.

Animals↗

PubMed1998

Analyses of monoclonal antibodies reacting with porcine CD3: results from the Second International Swine CD Workshop.

Among the 57 monoclonal antibodies (mAb) analyzed within the T-cell group from the Second Swine CD Workshop, six mAb fell within clusters T10 and T11 (No. 088, STH164; No. 148, FY1A3; No. 149, FY2C1; No. 150, FY1H2; No. 151, FY2A11; No. 169, BB23-8E6). The mAb within these two groups gave a similar appearance on flow cytometry and stained all peripheral blood T-cells as defined by CD4 and wCD8 staining. All six mAb precipitated a 24 kDa protein. On the basis of inhibition analyses performed as part of the workshop and from published data, the mAb define at least three epitopes. There is only minimal stimulation of resting peripheral lymphocytes, but four of the mAb produce strong stimulation in the presence of PMA. With the exception of STH164, all have been shown to react with CD3 epsilon-transfected COS cells. The new mAb, therefore, react with three epitopes on porcine CD3 epsilon designated CD3a (BB23-8E6, FY2A11), CD3b (FY1A3, FY2C1), and CD3c (FY1H2). mAb STH164 appears to be reactive with another epitope, however, since its reactivity with CD3 has not been confirmed it is designated as wCD3.

Animals↗

PubMed1998

Analyses of monoclonal antibodies reacting with porcine CD5: results from the Second International Swine CD Workshop.

Among the 57 monoclonal antibodies analyzed within the T-cell group, three mAbs fell within cluster T13 including the CD5a standard b53b7 (No. 174). The two new mAbs 1H6/8 (No. 058) and BB6-9G12 (No. 166) both precipitated 55 and 60 kDa proteins that were of similar molecular weights as the standard. Staining patterns on the various cell types were similar. Both new antibodies inhibited the binding of the CD5a reference mAbs b53b7 to peripheral lymphocytes. These mAbs, therefore both react with the CD5a epitope bringing the number of anti-porcine CD5 mAbs to eight, all of which appear to recognize the same epitope.

Animals↗

PubMed1998

Analyses of monoclonal antibodies reacting with porcine wCD6: results from the Second International Swine CD Workshop.

Among the 57 monoclonal antibodies analyzed within the T-cell group of the Second International Swine CD Workshop, one mAb fell within cluster T14a that included the CD6 standard a38b2 (No. 175). The new mAb MIL8 (No. 082) and a38b2 both precipitated from activated T-cells a 150 kDa monomeric protein. Staining patterns on the various cell types were similar. There was no inhibition of binding of either mAb to peripheral blood T-cells with the opposite mAb. The new mAb, MIL8, reacts with a separate epitope on porcine wCD6.

Animals↗

PubMed1998

Report on the analyses of mAb reactive with porcine CD8 for the second international swine CD workshop.

Based on an analysis of their reactivity with porcine peripheral blood lymphocytes (PBL), only three of the 57 mAbs assigned to the T cell/activation marker group were grouped into cluster T9 along with the two wCD8 workshop standard mAbs 76-2-11 (CD8a) and 11/295/33 (CD8b). Their placement was verified through the use of two-color cytofluorometry which established that all three mAbs (STH101, #090; UCP1H12-2, #139; and PG164A, #051) bind exclusively to CD8+ cells. Moreover, like the CD8 standard mAbs, these three mAbs reacted with two proteins with a MW of 33 and 35 kDa from lymphocyte lysates and were, thus, given the wCD8 designation. Because the mAb STH101 inhibited the binding of mAb 76-2-11 but not of 11/295/33, it was given the wCD8a designation. The reactivity of the other two new mAbs in the T9 cluster with the various subsets of CD8+ lymphocytes were distinct from that of the other members in this cluster including the standards. Although the characteristic porcine CD8 staining pattern consisting of CD8low and CD8high cells was obtained with the mAb UCP1H12-2, a wider gap between the fluorescence intensity of the CD8low and CD8high lymphocytes was observed. In contrast, the mAb PG164A, not only exclusively reacted with CD4-/CD8high lymphocytes, but it also failed to recognize CD4/CD8 double positive lymphocytes. It was concluded that this mAb is specific for a previously unrecognized CD8 epitope, and was, thus, given the wCD8c designation. A very similar reactivity pattern to that of PG164A was observed for two other mAbs (STH106, #094; and SwNL554.1, #009). Although these two mAbs were not originally positioned in the T cell subgroup because of their reactivity and their ability to inhibit the binding of PG164A, they were given the wCD8c designation. Overall, five new wCD8 mAbs were identified. Although the molecular basis for the differences in PBL recognition by these mAbs is not yet understood, they will be important in defining the role of CD8+ lymphocyte subsets in health and disease.

Animals↗

PubMed1998

The expression of histone genes during Drosophila melanogaster oogenesis.

A genomic fragment was cloned from a DNA library constructed from a Drosophila enhancer trap line in which reporter gene expression was observed at the anterior-most tip of the ovaries and testes. This genomic clone was identified as the L-repeat of the Drosophila melanogaster histone gene cluster. Northern blotting and in situ hybridisation to RNA in tissues with individual cDNAs and PCR-generated probes for each histone confirmed that gene expression was greatest at the anterior portion of each ovariole, in the germarium, and was also elevated in a few individual nurse cells and somatic follicle cells within the egg chamber during early developmental stages. Histone H1 and each of the core histones had a similar expression pattern which was correlated to cell division. Maternal stores of histone transcripts were also transported to the mature oocyte from the nurse cells at a later stage of oogenesis (stage 10), when virtually all the nurse cells contained high levels of histone transcripts. The results are consistent with expression of the somatic histone gene cluster during oogenesis as a co-ordinate unit. There does not seem to be a reduced level of somatic type H1 in the germ-line, as is observed in some other species. The relationship between the P[lacZ] expression pattern in the germarium and the overall expression of the histone cluster suggests there are specific regulatory elements for germ-line expression.

Animals↗

PubMed1998

Malaria in a changing world: an Australian perspective.

Three elements must be present for endemic malaria: infected humans, susceptible mosquitoes and a suitable climate. All three occur in parts of Australia and yet this country has always been a region of marginal malaria endemicity. With the exception of a large epidemic in Cairns during the Second World War, most outbreaks have occurred in small, isolated populations of the Northern Territory. The last epidemic was at the Roper River Mission in the Northern Territory in 1962. Since Australia was declared to be free of endemic malaria in 1983, only sporadic cases of local transmission have occurred. There have been suggestions that future climate change may increase the range of the major vector in Australia, Anopheles farauti, and consequently lead to the re-establishment of endemic malaria. This possibility is discussed in relation to experiences in this and other regions. It is stressed that climate change in only one component in a complex epidemiological setting, and that other aspects such as human activity are probably more important.

Animals↗

PubMed1998

Protection from primary infection and establishment of latency by vaccination with a herpes simplex virus type 1 recombinant deficient in the virion host shutoff (vhs) function.

A herpes simplex virus type 1 (HSV-1) recombinant virus deficient in the virion host shutoff (vhs) function was assessed for its ability to function as a live-attenuated vaccine. Protection of mice from wild-type challenge infection and the establishment and reactivation of HSV-1 latency was measured in a mouse ocular model. Challenge virus replication in corneas and trigeminal ganglia was significantly reduced for vaccinated mice. Consistent with these findings, the vaccinated groups showed no clinical signs during acute infection and high levels of virus-specific IgG and neutralizing antibodies were induced. The establishment of and reactivation from latency in trigeminal ganglia from the vaccinated group were also significantly reduced relative to controls. These data suggest that vhs deletion mutants may have significant utility as live-attenuated HSV-1 vaccines.

Animals↗

PubMed1998

Postexposure vaccination with a virion host shutoff defective mutant reduces UV-B radiation-induced ocular herpes simplex virus shedding in mice.

A herpes simplex virus type 1 (HSV-1) recombinant (UL41NHB) deficient in the virion host shutoff (vhs) function was tested as a therapeutic vaccine in an ultraviolet (UV) light-induced mouse ocular reactivation model. Mice were infected with HSV-1 via the cornea. Following the establishment of latency by HSV-1 the mice were subsequently vaccinated intraperitoneally with one dose of UL41NHB or with uninfected cell extract. Mice were subsequently UV-irradiated to induce viral reactivation and during the 7 days post-UV irradiation, numbers of mice shedding virus were reduced from 13/23 (57%) to 3/25 (12%), and numbers of virus-positive eye swabs were reduced from 40/161 (25%) to 6/175 (3%) by the vaccine (P < 0.001). These data suggest that deletion of vhs may be a useful strategy in the development of attenuated therapeutic HSV vaccines.

Animals↗

PubMed1998

Maximising the world wide web for high quality educational and clinical support to health and medical professionals in rural areas.

Attracting and retaining medical and allied health professionals to rural and remote regions is a perennial problem, world-wide. It is exacerbated by the associated problem of providing high quality, cost-effective educational and clinical support to health professionals and trainees located in such areas. The world wide web is being used as a tool to address these twin problems to provide a means of communication, interaction and educational and clinical support to geographically dispersed and isolated pools of users. An interactive electronic notice board has been developed as a clinical problems' discussion forum to act as a venue for critical debate about clinical issues and to provide a searchable archive of information to assist in the management of clinical problems. A description of the forum will demonstrate the potential of the world wide web as a learning and a clinical support tool.

Australia↗

PubMed1998

Epidemiological characterization of methicillin-resistant Staphylococcus aureus isolated in the North West of England by protein A (spa) and coagulase (coa) gene polymorphisms.

In a comparative study, isolates of methicillin-resistant Staphylococcus aureus (MRSA) with known pulsed-field gel electrophoresis (PFGE) and bacteriophage type were analysed by polymerase chain reaction (PCR) and restriction fragment length polymorphisms (RFLP) for additional discriminatory subtyping information. PFGE was previously performed using standardized, commercially available kits and pre-programmed software. Isolates were examined for coagulase (coa) and protein A (spa) gene polymorphisms following PCR amplification of the coa hypervariable and spa repeat regions. Coa gene RFLPs produced a total of 38 distinct combined patterns after digestion with HaeIII and AluI and identified the predominant epidemic (EMRSA) types 15 and 16. A unique HaeIII restriction site was identified by RFLP and sequence analysis in the coa gene for EMRSA 15 but not EMRSA 16. The spa gene PCR yielded a total of 14 different profiles ranging from 3-18 repeats with the 2 predominant EMRSA types falling into 2 distinct groups. PCR detection of coa and spa polymorphisms offer a rapid preliminary strain identification and discriminatory subtyping information for surveillance of MRSA.

Bacteriophage Typing↗

PubMed1998

Predictors of psychological distress in chronic pain patients.

The purpose of this study was to identify sources of psychological distress in patients attending pain clinics. Patients attending two pain clinics in the UK completed a self-report assessment questionnaire which included a 12-item, 5-point semantic differential measure of psychological well-being/distress, together with a range of single-item measures of pain and psychosocial factors measured using 5-point verbal report scales. Multiple regression analysis identified that 60% of the variance associated with psychological distress was explained by a combination of fears about the future, regrets about the past, age (younger people were more distressed), practical help (more help was associated with more distress), feeling unoccupied and personal relationship problems. These results support previous findings which have suggested that a significant proportion of the emotional disturbance in chronic pain patients is associated with psychosocial factors which are either secondary to, or concurrent with, the pain. The method described provides a simple and quick method of assessment which may be used by nurses in clinical settings to identify sources of psychological distress in patients with chronic pain and opportunities for therapeutic intervention.

Adaptation, Psychological↗

PubMed1998

Patient perceptions of hospital care: building confidence, faith and trust.

AIM: The aim of this study was to understand how people evaluate and make sense of their experience of hospital care. METHOD: Narrative interviews were conducted with 18 patients between 4-6 weeks after an episode of inpatient care or day surgery. Participants were deliberately sampled from a population who participated in a hospital-wide audit which took place during 1 week in June 1995. Sampling criteria ensured a mix of age, gender, type of, and reason for, admission. The interviews were audiotaped, transcribed and analysed using grounded theory. FINDINGS: Three categories: 'feeling informed', 'valued as an individual', and 'at home' contributed to a core category: 'building confidence, faith and trust'. Notably, confidence and trust were determined as much by observations of the care given to other people, as the care the participants themselves had received. CONCLUSIONS: More attention needs to be given to understanding the complex social and reflective process which underpin patient judgements about quality of care.

Adult↗