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Biomedical subjects

F Cooke

Publications and source records attributed to F Cooke.

At least 19 recordsLinked to original sources
PubMed1999

CD34+-selected peripheral blood progenitor cell transplantation in patients with multiple myeloma: tumour cell contamination and outcome.

Thirty-six patients with multiple myeloma (23 PR1, nine PR2, four stable disease) were entered into a pilot study evaluating the use of CD34+-selected peripheral blood progenitor cell transplantation (PBPCT) following high-dose melphalan alone or high-dose melphalan and total body irradiation. Peripheral blood progenitor cells (PBPCs) were mobilized with cyclophosphamide and granulocyte colony stimulating factor (G-CSF). CD34+ selection using the Cellpro Ceprate-SC system was performed in 22 cases with an adequate yield in 20. 10 patients failed to mobilize sufficient cells to permit selection and in four cases selection was not performed for other reasons. 16 patients therefore received unselected PBPC. Tumour cell contamination was evaluated by IgH gene fingerprinting (fpPCR). Harvested PBPC were fpPCR positive in 13/20 CD34+-selected cases and remained positive after selection in seven. Harvested PBPC were studied in 9/16 patients receiving unselected cells; fpPCR was positive in five and negative in four. There was no difference in event-free survival (EFS) between the CD34+-selected group and the unselected group (median 21 and 26 months, respectively, P=ns). The CD34+-selection process therefore reduced contamination but did not eliminate it completely, and in this small non-randomized study there was no apparent clinical benefit of CD34+ selection.

Adult↗
PubMed1999

Phenotypic and molecular analysis of six human cell lines derived from patients with plasma cell dyscrasia.

Cell lines RPMI 8226, JJN3, U266 B1, NCI-H929 (all EBV-) and ARH77 and HS-Sultan (both EBV+) have been extensively characterized in this study. EBV- lines expressed the phenotype (CD138-, CD19+, CD20+) whereas EBV+ were (CD138+, CD19-, CD20-). CD56 expression was restricted to EBV- cell lines, with the exception of U266 B1, whereas PCA-1 was strongly expressed on five of the six cell lines. Only EBV+ cell lines bound peanut-agglutinin (PNA). However, all cell lines bound the lectin Jacalin that binds the same receptor as PNA, irrespective of the receptors sialylation status. By RT-PCR and direct sequencing of their IgH V/D/J domains, ARH77 was demonstrated to use the germline sequence VH4-34/dm1/JH6b, whereas no arrangement was demonstrated for RPMI 8226, suggesting IgH gene deletion or mutation. HLA class I and II antigens were detected using HLA typing on all cell lines warranting their use as suitable targets for HLA-restricted cytotoxic T cells. By sensitive RT-PCR, mRNA for IL-6, IL-6R and TNFbeta was found expressed in all cell lines. IL-1 mRNA expression was predominantly associated with the EBV+ phenotype. Although mRNA for IL-3 and GM-CSF was never detected, transcripts for c-kit ligand and, more commonly, its receptor were. Likewise GM-CSF, M-CSF and erythropoietin mRNA transcripts were detected in the majority of cell lines.

Base Sequence↗
PubMed1998

Moult speed predicts pairing success in male harlequin ducks.

The bright plumage of male ducks in sexually dichromatic species is thought to have evolved through intense sexual selection. This study examined the relationship between the timing and speed of moult into this bright plumage and subsequent mating success of male harlequin ducks, Histrionicus histrionicus. Males that moulted relatively slowly had a lower chance of establishing a pair bond than others. The timing of moult was unrelated to whether a male obtained a mate. Moult speed and timing were not correlated within individual males, but were significantly repeatable in individual males over 2 years. Moult speed probably reflects the condition of males, whereas timing of moult is more likely to be related to the distance to an individual's breeding area, which determines the timing of arrival to the moulting grounds. In waterfowl species that have been studied, males usually form dominance hierarchies before pairing and females tend to choose dominant males. We suggest that male harlequin ducks that moult slowly are poor-quality individuals, which are relegated to subordinate status and are unlikely to attract a mate the following autumn. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

A methodology for sampling and accessing homeless individuals in Melbourne, 1995-96.

A methodology for sampling homeless populations in inner Melbourne was developed to study their health status and prevalence of tuberculosis. This paper describes the design, development and implementation of the project. The results of health status and tuberculosis analysis are published elsewhere. Involvement and interaction with local service providers and agencies to homeless people was central to the project throughout. A definitional construct of homelessness was developed, drawn from local and overseas literature and contemporary local experience. The study's aim was to obtain a representative sample of homeless individuals in various levels of accommodation and a convenience sample of those who were unaccommodated (streets and parks). A comprehensive sampling frame of accommodation options was constructed from available databases, and systematic sampling applied to produce a sample of 396 beds, from which 284 participants were enrolled. Convenience sampling of unaccommodated homeless individuals produced 100 participants. All agreed to undergo a comprehensive questionnaire, blood and Mantoux testing, the latter being completed successfully in 94%. Commonsense, cultural sensitivity and a non-threatening approach were critical to the success of the project and the security of the field workers. The methods described attempt to address recognised difficulties of sampling from homeless populations and should be reproducible both in the future and elsewhere. Potential for selection bias remains the main threat to validity, which the described methodology combined with adequate resources should help to address.

Health Surveys↗
PubMed1997

The G beta gamma sensitivity of a PI3K is dependent upon a tightly associated adaptor, p101.

Two highly similar, PtdIns(4,5)P2-selective, G beta gamma-activated PI3Ks were purified from pig neutrophil cytosol. Both were heterodimers, were composed of a 101 kDa protein and either a 120 kDa or a 117 kDa catalytic subunit, and were activated greater than 100-fold by G beta gammas. Peptide sequence-based oligonucleotide probes were used to clone cDNAs for the p120 and p101 species. The cDNA of p120 is highly related to p110 gamma, while the cDNA of p101 is not substantially related to anything in current databases. The proteins were expressed in and purified from insect and mammalian cells. They bound tightly to one another, both in vivo and in vitro, and in so doing, p101 amplified the effect of G beta gammas on the PI3K activity of p120 from less than 2-fold to greater than 100-fold.

Amino Acid Sequence↗
PubMed1996

A heterotrimeric GTPase-regulated isoform of PI3K and the regulation of its potential effectors.

We have purified two forms of phosphoinositide 3-kinase (PI3K) that are activated by heterotrimeric G-protein beta gamma-subunits. These novel isoforms of PI3K are structurally distinct to those forms of PI3K which have already been cloned. They are both heterodimers made up of a p120 and a p101 and a p117 and a p101 protein. The p101 species in both heterodimers are identical and show no substantial homology with any other proteins or DNA sequences. The p117 and p120 are highly related. The p101 and p120 species have been cloned from a pig neutrophil mRNA library. The p120 has similarities with other known PI3K catalytic subunits. They may be responsible for conferring cells with the capacity to produce phosphatidylinositol (3,4,5)-trisphosphate in response to activation of G-protein-coupled receptors. Activation of both the monomeric G-protein rac and PI3K(s) have been implicated in receptor-stimulated membrane-ruffling. We have observed that agonist-stimulated guanine nucleotide exchange on rac can be inhibited by a variety of PI3K inhibitors. This suggests PI3K may lie upstream of rac in receptor-driven pathways regulating cell movement.

Enzyme Activation↗
PubMed1996

Initiation and maintenance of NGF-stimulated neurite outgrowth requires activation of a phosphoinositide 3-kinase.

Application of nerve growth factor (NGF) to PC12 cells stimulates a programme of physiological changes leading to the development of a sympathetic neuron like phenotype, one aspect of which is the development of a neuronal morphology characterised by the outgrowth of neuritic processes. We have investigated the role of phosphoinositide 3-kinase in NGF-stimulated morphological differentiation through two approaches: firstly, preincubation with wortmannin, a reputedly specific inhibitor of phosphoinositide kinases, completely inhibited initial morphological responses to NGF, the formation of actin filament rich microspikes and subsequent neurite outgrowth. This correlated with wortmannin inhibition of NGF-stimulated phosphatidylinositol(3,4,5)trisphosphate (PtdInsP3) and phosphatidylinositol(3,4)bisphosphate (PtdIns(3,4)P2) production and with inhibition of NGF-stimulated phosphoinositide 3-kinase activity in anti-phosphotyrosine immunoprecipitates. Secondly, the overexpression of a mutant p85 regulatory subunit of the phosphoinositide 3-kinase, which cannot interact with the catalytic p110 subunit, also substantially inhibited the initiation of NGF-stimulated neurite outgrowth. In addition, we found that wortmannin caused a rapid collapse of more mature neurites formed following several days exposure of PC12 cells to NGF. These results indicate that NGF-stimulated neurite outgrowth requires the activity of a tyrosine kinase regulated PI3-kinase and suggest that the primary product of this enzyme, PtdInsP3, is a necessary second messenger for the cytoskeletal and membrane reorganization events which occur during neuronal differentiation.

Androstadienes↗
PubMed1996

Medical students in general practice: how do patients feel?

BACKGROUND: The General Medical Council has recommended that medical students should gain more experience in general practice. AIM: The study set out to determine patients' reactions to the presence of medical students in general practice consultations. METHOD: Patients attending a random sample of general practice surgeries completed a questionnaire following consultation with and without a medical student present in six general practices in the Oxford area. RESULTS: The questionnaires were completed by 278 patients. Only eight (3%) of all respondents had negative responses to the presence of a medical student. Of those completing questionnaires following a teaching consultation, 107 (56%) felt positively about the presence of students, compared with 36 (41%) who had attended a nonteaching surgery. Only three patients (1%) felt the quality of the consultation to be impaired by the presence of a student, while 48 patients (17%) felt there to be some improvement. The majority felt that the sex of the student was unimportant, but significantly more female than male patients (17% versus 5%) felt that it made a difference. CONCLUSION: Only a small proportion of patients object to the presence of a medical student in general practice consultations. A significant minority said that the presence of a student improves the consultation.

Attitude to Health↗
PubMed1994

Activation of phosphoinositide 3-kinase is required for PDGF-stimulated membrane ruffling.

BACKGROUND: There is substantial evidence that phosphoinositide 3-kinase (PI 3-kinase) is a critical component of signalling pathways used by the cell-surface receptors for a variety of mammalian growth factors and other hormones. The physiological product of this enzyme is a highly polar membrane lipid called phosphatidylinositol (3,4,5)-trisphosphate This lipid has been postulated to act as a second-messenger in cells but its putative targets are still unknown. RESULTS: A particular rearrangement of actin filaments, which results in membrane ruffling, is elicited by the activation of PDGF beta-receptors expressed in cultured porcine aortic endothelial cells. We have found that this consequence of PDGF beta-receptor activation is inhibited by three independent manipulations of PI 3-kinase activity: firstly, by the deletion of tyrosine residues in the PDGF beta-receptor to which PI 3-kinase binds; secondly, by the overexpression of a mutant 85 kD PI 3-kinase regulatory subunit to which the catalytic kinase subunit cannot bind; and thirdly, by the addition of the fungal metabolite wortmannin, which is a potent inhibitor of the catalytic activity of PI 3-kinase. CONCLUSIONS: These results argue strongly that phosphatidylinositol (3,4,5)-trisphosphate synthesis is required for growth-factor-stimulated membrane ruffling in porcine aortic endothelial cells, and suggest that synthesis of this lipid may be part of a signalling pathway leading to direct or indirect activation of the small GTP-binding protein Rac.

Androstadienes↗
PubMed1993

Characterization of metal ion-induced [3H]inositol hexakisphosphate binding to rat cerebellar membranes.

The binding of [3H]inositol hexakisphosphate ([3H] InsP6) to rat cerebellar membranes has been characterized with the objective of establishing the role, if any, of a membrane protein receptor. In the presence of EDTA, we have previously identified an InsP6-binding site with a capacity of approximately 20 pmol/mg protein (Hawkins, P. T., Reynolds, D. J. M., Poyner, D. R., and Hanley, M. R. (1990) Biochem. Biophys. Res. Commun. 167, 819-827). However, in the presence of 1 mM Mg2+, the capacity of [3H]InsP6 binding to membranes was increased approximately 9-fold. This enhancing effect of Mg2+ was reversed by addition of 10 microM of several cation chelators, suggesting that the increased binding required trace quantities of other metal cations. This is supported by experiments where it was possible to saturate binding by addition of excess membranes, despite not significantly depleting radioligand, pointing to removal of some other factor. Removal of endogenous cations from the binding assay by pretreatment with chelex resin also prevents the Mg(2+)-induced potentiation. Consideration of the specificity of the chelators able to abolish this potentiation suggested involvement of Fe3+ or Al3+. Both these ions (but not several others) were able to increase [3H]InsP6 binding to chelex-pretreated membranes at concentrations of 1 microM. It is possible to demonstrate synergy between Fe3+ and Mg2+ under these conditions. We propose that [3H]InsP6 may interact with membranes through non-protein recognition, possibly via phospholipids, in a manner dependent upon trace metals. The implications of this for InsP6 biology are considered.

Animals↗
PubMed1993

Plastics processing: statistics, current practices, and evaluation.

The health care industry uses a huge quantity of plastic materials each year. Much of the machinery currently used, or supplied, for plastics processing is unsuitable for use in a clean environment. In this article, the author outlines the reasons for the current situation and urges companies to re-examine their plastic-processing methods, whether performed in-house or subcontracted out. Some of the factors that should be considered when evaluating plastics-processing equipment are outlined to assist companies in remaining competitive and complying with impending EC regulations on clean room standards for manufacturing areas.

Environment, Controlled↗
PubMed1991

Treatment of the unstable intertrochanteric fracture. Effect of the placement of the screw, its angle of insertion, and osteotomy.

We created unstable intertrochanteric fractures with a large posteromedial defect in eighteen pairs of fresh-frozen femora from cadavera, and used the femora to evaluate the stability of six combinations of treatment with sliding compression screws and sideplates. The variables that were tested were high (150-degree) angle plates compared with low (130-degree) angle plates, the position of the lag-screw in the femoral head and neck (in the center of the head as seen on both anteroposterior and lateral roentgenograms compared with posteroinferiorly), and whether or not medial cortical contact had been re-established with a limited osteotomy of the greater trochanter. The femora were loaded to the point of failure. The mode of failure, maximum load to failure, and bending rigidity of each method of fixation were measured. Of the six types of treatment, the use of a 150-degree-angle plate, position of the lag-screw in the center of the head as seen on both anteroposterior and lateral roentgenograms, and osteotomy of the greater trochanter resulted in the highest mean load to failure and the greatest rigidity. Over-all, re-establishment of medial cortical contact by means of an osteotomy of the greater trochanter significantly improved the mean load to failure and the rigidity of the fixation. The higher-angle plate, although more difficult to insert, increased the mean load to failure but had no effect on rigidity. The position of the lag-screw (in the center of the head as seen on both anteroposterior and lateral roentgenograms or posteroinferiorly) had no bearing on the mean load to failure, but it significantly affected the mode of failure.

Biomechanical Phenomena↗
PubMed1990

Seasonal changes in gonadal steroids of a monogamous versus a polyandrous shorebird.

We examined the relationship between circulating levels of gonadal steroids (testosterone, progesterone, and estradiol) and breeding behavior in semipalmated sandpipers (Calidris pusilla) and red-necked phalaropes (Phalaropus lobatus) breeding sympatrically at La Pérouse Bay, 40 km east of Churchill, Manitoba. Semipalmated sandpipers are territorial and monogamous. Both parents incubate equally. Red-necked phalaropes are nonterritorial and polyandrous. Only male phalaropes care for eggs and young. Gonadal steroid hormone profiles were not reversed in the sex-role-reversed species. There was little difference in testosterone profiles between males of the territorial and nonterritorial species.

Animals↗
PubMed1990

A prospective randomised controlled trial of antimicrobial prophylaxis in hydrocephalus shunt surgery.

Despite attempts to reduce their incidence, shunt infections remain a major complication of the treatment of hydrocephalus. Various forms of antimicrobial prophylaxis are in use, but no controlled, statistically valid trial has been conducted to assess their efficacy. Such a trial was therefore carried out and its design is described here. After a 1-year retrospective and prospective study by members of the United Kingdom Hydrocephalus Group to establish feasibility and infection rates, a statistical study showed that at least 712 patients would be required. Six centres were enrolled to fulfil these requirements, and ethical committee approval was obtained at each. The chosen prophylactic regimen was 10 mg vancomycin administered into the ventricular system during surgery. Adults and children undergoing insertion or revision of ventriculoperitoneal shunts were included unless they were receiving therapeutic antimicrobials. Randomisation was by computer-generated numbers. Controls received the antimicrobial regimen, if any, currently used in that centre, the only difference between the two groups being intraventricular vancomycin in the test group. Diagnosis of shunt infection included accepted clinical and microbiological criteria reinforced by measurement of serum C-reactive protein levels. Follow-up was for at least six months. After 2.5 years only 158 patients had been enrolled in the trial, 80 controls and 78 tests. There were 5 preventable infections in the control group and 2 in the test group. In view of the small total the planned statistical analysis was not possible. Therefore, while no problems were encountered with toxicity, the trial failed to enroll enough patients to answer the question of efficacy of antimicrobial prophylaxis in shunt surgery and the reasons for this are discussed.

Cerebrospinal Fluid Shunts↗
PubMed1977

Isoenzyme status and genetic variability of serum esterases in the lesser snow goose, Anser caerulescens caerulescens.

A maximum of 22 bands comprising four esterase subgroups--acetylesterase, carboxylesterase, cholinesterase, and acetylcholinesterase--were detected following electrophoresis of lesser snow goose sera on polyacrylamide gels. A minimum of seven structural genes was surmised to be involved in the biosynthesis of these enzymes following physiochemical characterizations. The genetic variability of these loci was calculated to be 1.25% average heterozygosity, while 14.3% of the loci were polymorphic. These estimates of genetic variability were substantially lower than those reported for other vertebrate species. The low degree of genetic variability found in snow goose serum esterases coupled with the extensive protein multiplicity observed may possibly reflect an adaptive strategy based on "biochemical plasticity" rather than genic heterozygosity for this species. The nature of evolutionary forces acting upon multiple enzyme systems such as esterases is discussed. The concept of "conditional neutrality" is introduced and defined within this context.

Animals↗