Biomedical subjects
Publications and source records attributed to S Kelly.
The anticancer drug etoposide, 1, is prepared in 79% overall yield from readily available 4'-demethyl-4-epipodophyllotoxin, 3, and 4, 6-O-ethylidene-2,3-O-dibenzyl-D-glucose, 4, via a crystallization-induced stereoselective glycosidation reaction followed by catalytic hydrogenation.
Adenosine deaminase (ADA) deficiency results in a combined immunodeficiency brought about by the immunotoxic properties of elevated ADA substrates. Additional non-lymphoid abnormalities are associated with ADA deficiency, however, little is known about how these relate to the metabolic consequences of ADA deficiency. ADA-deficient mice develop a combined immunodeficiency as well as severe pulmonary insufficiency. ADA enzyme therapy was used to examine the relative impact of ADA substrate elevations on these phenotypes. A "low-dose" enzyme therapy protocol prevented the pulmonary phenotype seen in ADA-deficient mice, but did little to improve their immune status. This treatment protocol reduced metabolic disturbances in the circulation and lung, but not in the thymus and spleen. A "high-dose" enzyme therapy protocol resulted in decreased metabolic disturbances in the thymus and spleen and was associated with improvement in immune status. These findings suggest that the pulmonary and immune phenotypes are separable and are related to the severity of metabolic disturbances in these tissues. This model will be useful in examining the efficacy of ADA enzyme therapy and studying the mechanisms underlying the immunodeficiency and pulmonary phenotypes associated with ADA deficiency.
We generated purine nucleoside phosphorylase (PNP)-deficient mice to gain insight into the mechanism of immune deficiency disease associated with PNP deficiency in humans. Similar to the human disease, PNP deficiency in mice causes an immunodeficiency that affects T lymphocytes more severely than B lymphocytes. PNP knockout mice exhibit impaired thymocyte differentiation, reduced mitogenic and allogeneic responses, and decreased numbers of maturing thymocytes and peripheral T cells. T lymphocytes of PNP-deficient mice exhibit increased apoptosis in vivo and higher sensitivity to gamma irradiation in vitro. We propose that the immune deficiency in PNP deficiency is a result of inhibition of mitochondrial DNA repair due to the accumulation of dGTP in the mitochondria. The end result is increased sensitivity of T cells to spontaneous mitochondrial DNA damage, leading to T cell depletion by apoptosis.
The COOH-terminal domain of the NR2D subunit of the NMDA receptor contains proline-rich regions that show striking homology to sequences known to bind to Src homology 3 (SH3) domains. To determine whether the proline-rich region of the NR2D subunit interacts with specific SH3 domains, in vitro SH3 domain binding assays were performed. A proline-rich fragment of the NR2D subunit (2D(866-1064)) bound to the Abl SH3 domain but not to the SH3 domains from Src, Fyn, Grb2, GAP, or phospholipase C-gamma (PLCgamma). Co-immunoprecipitation of NR2D with Abl suggests stable association of NR2D and Abl in transfected cells. The SH3 domain plays an important role in the negative regulation of Abl kinase activity. To determine whether the interaction of NR2D with the Abl SH3 domain alters Abl kinase activity, Abl was expressed alone or with NR2D in 293T cells. Autophosphorylation of Abl was readily observed when Abl was expressed alone. However, co-expression of Abl with 2D(866-1064) or full-length NR2D inhibited autophosphorylation. 2D(866-1064) did not inhibit DeltaSH3 Abl, indicating a requirement for the Abl SH3 domain in the inhibitory effect. Similarly, 2D(866-1064) did not inhibit the catalytic activity of Abl-PP, which contains two point mutations in the SH2-kinase linker domain that release the negative kinase regulation by the SH3 domain. In contrast, the full-length NR2D subunit partially inhibited the autokinase activity of both DeltaSH3 Abl and Abl-PP, suggesting that NR2D and Abl may interact at multiple sites. Taken together, the data in this report provide the first evidence for a novel inhibitory interaction between the NR2D subunit of the NMDA receptor and the Abl tyrosine kinase.
Efficacy of silver-coated poly(ethylene terephthalate) to prevent bacterial attachment and subsequent infection was quantified in vitro, in both batch- and flowing-fluid experiments. Kinetic analysis of batch suspended cell cultures of Staphylococcus epidermidis (SE), at various growth-limiting nutrient concentrations, in the absence of any fabric, indicated a maximum culture growth rate constant micro(max) = 0.78 +/- 0.02 h(-1). Batch experiments for Control fabric samples indicated that SE cultures exhibited about the same suspended cell growth rate (0.72 +/- 0.02 h(-1)) as observed in batch suspended cultures without fabric. Suspended SE cultures in the presence of silver-coated fabric grew at a considerably lower rate, 0.15 +/- 0.01 h(-1), indicating the inhibitory effect of Ag(+2) ion released from the fabric. Growth rates of suspended SE cultures were 5-6 times higher in the fluid phase in contact with the Control fabric compared to cultures exposed to silver-coated fabric. Maximum suspended cell concentrations attained at time = 24 h were 1-2 orders of magnitude higher for Control fabrics vs. silver-coated fabric. In all batch colonization experiments, both live and dead SE bacterial cells accumulate on the surfaces of both silver-coated and Control fabrics. Adherent viable SE cells accumulated to 1-2 orders of magnitude more ( approximately 5 x 10(+8) cells/cm(2)) on Control fabric than SE cells on the silver-coated fabric ( approximately 1.1 x 10(+6) cells/cm(2)), respectively. Between 70-95% SE cells on the Control fabric were viable, while on the silver-coated fabric samples, at 24 h, viable cells were less than 10% of the adherent community (i.e., greater than 90% nonviable cells). In flow cell colonization experiments, SE cells accumulated on Control fabric to a maximum adherent cell concentration of 6 x 10(+7) - 8 x 10(+7) cells/cm(2) by 24 h with the proportion of viable cells remaining relatively constant at 76% throughout an experiment. Both noninvasive microscopic enumeration and destructive assays gave the same results for adherent cell numbers. Using silver-coated fabric, total cells numbers (live + dead) reached a level of approximately 1.1 x 10(+7) - 3.0 x 10(+7) cells/cm(2) after about 6 h and remained constant. However, while the proportion of viable cells initially on the surface was 63-75%, this fraction dropped continuously during each experiment to less than 6% viable cells at 24 h. Regardless of the criteria, the number of viable or nonviable cells attached to silver-coated fabric were significantly lower than on Control fabric.
The 5q- syndrome is a distinct subtype of myelodysplastic syndrome (MDS) characterized by refractory anemia, deletion of the long arm of chromosome 5, del(5q), as the sole cytogenetic abnormality, and a low frequency of transformation to acute leukemia. Using combined immunophenotyping and fluorescence in situ hybridization (FISH), studies were carried out on bone marrow smears of three 5q- syndrome cases to identify the cell lineages carrying the 5q deletion. In all three cases, the granulocytic, monocytic, and erythroid lineages possessed the del(5q) clonal marker, whereas the T-lymphocytes did not. Interestingly, in one case, cells of B-lymphoid lineage also showed the presence of the del(5q). This is the first report to date showing involvement of an acquired 5q deletion associated with MDS in B-cells. This result suggests that in some cases, MDS arises in a multipotent cell with a capacity to differentiate into both myeloid and lymphoid cells.
Quantitative analysis of functional cardiac magnetic resonance (MR) images has been limited by the lack of well-validated, semiautomatic, methods for rapid analysis. We describe the evaluation of a DICOM-compatible PC-based parallel-processing tool, for cardiac magnetic resonance analysis (CAMRA), which supports semiautomatic image mensuration using an active contour model-based algorithm. The CAMRA software was used to analyze data from 12 patients in a multicenter acquisition and analysis trial to compare semiautomatic contour detection with manual planimetry of the left ventricular endocardium from short-axis, breath-held, cine gradient-echo images. There was excellent agreement between the manual and semiautomatic measurements of global left ventricular function, with no significant (P = 0.32) difference in the determination of ejection fraction (-0.9 +/- 3.1% [mean difference +/- 1 standard deviation]). There was no significant interobserver difference in the semiautomatically measured ejection fraction. Additionally, a single observer completed the analysis on data from 30 patients and found no significant (P = 0.05) difference in the determination of ejection fraction (-1.3 +/- 3.5% [mean difference +/- 1 standard deviation]). The CAMRA software demonstrates the capability for the reproducible evaluation of global left ventricular function in cardiac patients, with adequate interobserver reproducibility for use in multicenter trials.
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This paper describes the technique of electropalatography and the development of Linguagraph, which is a user-friendly, clinical instrument, for measurement of tongue/palate contact, during speech. Linguagraph allows objective assessment of tongue function; appropriate targeting of therapy is therefore possible. Visual feedback is also provided, for therapy, and an objective measurement of outcome is easily obtained. Linguagraph was used, for both therapy and assessment, in a clinical trial. Technical aspects of Linguagraph and of the trial results are presented here. These suggest that the instrument will prove useful in the assessment and management of many speech disorders. Full clinical details of the trial are reported elsewhere.
OBJECTIVES: To determine if published figures on the proportion of articles included in systematic reviews and identified in electronic databases are applicable to an example from medical imaging. METHODS: A systematic review was performed. Additionally, sensitivity and precision of a MEDLINE search were compared with values from three published searches, each customized for a specific field. RESULTS: All articles included in the systematic review were in electronic databases. The MEDLINE search had low precision compared with searches in other fields. CONCLUSIONS: In a specific area of medical imaging, electronic databases, including MEDLINE, are reliable sources of articles.
BACKGROUND: Cerebral arteriolar tone is modulated in response to changes in transmural pressure and luminal flow. The effect of flow on the relation between pressure and diameter has not been fully evaluated in these vessels. This study was conducted to investigate this interaction and to determine the role of the endothelium in mediating it. METHODS: Rat pial arterioles from the territory of the posterior cerebral artery were mounted in a perfusion myograph. In some arterioles, the endothelium was removed by air perfusion. Diameters were recorded at pressures from 20 to 200 mmHg in the presence and absence of flow (10 microl/min). The response to flow (0-30 microl/min) was recorded at 60 and 120 mmHg. RESULTS: In the absence of flow, endothelium-intact arterioles demonstrated tone at distending pressures between 40 and 140 mmHg. In the presence of flow, tone did not develop until pressure exceeded 100 mmHg, and the vessels remained active at pressures up to 200 mmHg. Endothelium-denuded arterioles developed tone at the same pressure when perfused as when unperfused, but perfused vessels were able to maintain active tone at higher pressures. At 60 mmHg, flow caused dilation if the endothelium was intact and constriction if it had been removed. At 120 mmHg, flow caused constriction. Endothelium-dependent flow-relaxation was inhibited by N(G)-nitro-L-arginine methyl ester (10(-5) M) and abolished by indomethacin (10(-5) M). CONCLUSION: Flow inhibits the development of pial arteriolar tone at low intraluminal pressures through endothelium-dependent mechanisms. Conversely, perfusion extends the upper limit of the myogenically regulated pressure range through endothelium-independent activation of arteriolar smooth muscle contraction.
During germination of spores of Bacillus species, a novel protease termed GPR initiates the degradation of a group of small acid-soluble spore proteins which protect the dormant spore's DNA from damage. Trypsin digestion of the zymogen of B. megaterium GPR removes approximately 15 kDa from the C-terminal end of the 46 kDa zymogen subunit, leaving a 30 kDa subunit. Single crystals of this truncated form of GPR have been obtained by the vapor-diffusion method using PEG 4000 as a precipitating agent. The crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 67.99, b = 105.34, c = 108.63 A, beta = 95.68 degrees. The cryofrozen crystals diffract X-rays to about 3.3 A using synchrotron radiation.
The objective of this study was to determine whether paternal occupational exposure to chlorophenol fungicides and their dioxin contaminants is associated with childhood cancer in the offspring of sawmill workers. We used data from 23,829 British Columbian sawmill workers employed for at least 1 continuous year between 1950 and 1985 in 11 sawmills that used chlorophenates. Probabilistic linkage of the sawmill worker cohort to the provincial marriage and birth files produced an offspring cohort of 19,674 children born at least 1 year after the initiation of employment in the period 1952-1988. We then linked the offspring cohort to the British Columbia Cancer Registry. We included all malignancies in cases younger than 20 years of age that appeared on the cancer registry between 1969 and 1993. We calculated standardized incidence ratios (SIRs) using the British Columbia population as a reference. A nested case-control analysis assessed the effects of paternal cumulative exposure and windows of exposure on the risk of developing cancer in the offspring. We identified 40 cases of cancer during 259,919 person-years of follow-up. The all-cancer SIR was 1.0 [95% confidence interval (CI), 0.7-1.4]; the SIR for leukemia was 1.0 (CI, 0.5-1.8); and the SIR for brain cancer was 1.3 (CI, 0.6-2.5). The nested case-control analysis showed slightly increased risks in the highest categories of chlorophenol exposure, although none was statistically significant. Our analyses provide little evidence to support a relationship between the risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in British Columbian sawmills.
A computerized monitoring system of senior house officers' evaluations of their education and training has been developed in the West Midlands. Four successive surveys over 2 years show some significant improvements in their education and training.
A highly specific enzyme linked immunosorbent assay (ELISA) for the detection of lactate dehydrogenase-1 (LD-1) has been developed. A competition assay is described with polyclonal antibody to LD-1 passively adsorbed on an ELISA 96-well plate, with non-labelled and labelled LD-1 antigen competing. The LD-1 antigen is conjugated to alkaline phosphatase (ALP) using the one step glutaraldehyde method. A linear range of 10-4000 U/L was obtained, and cross-reactivity was only observed with LD-2. It was possible to eliminate this cross-reactivity by carrying out the final incubation step at 65 degrees C. The developed assay was applied to the analysis of spiked serum and plasma samples and the recoveries obtained were acceptable.
OBJECTIVES: This paper investigates changes in the psychosocial and physical work conditions of the sawmill industry in British Columbia, Canada, over the past 35 years. METHODS: Shifts in work conditions were examined within the context of historical changes in sawmill labor demography and job taxonomy as the industry was both downsized and restructured, largely in response to an economic recession in the early 1980s. RESULTS AND CONCLUSIONS: Downsizing eliminated approximately 60% of the work force and 1/4 of sawmill job titles. Although all the job categories in restructured sawmills showed increased levels of control, the gradient in control across job categories was steeper in 1997 than in 1965; this change may have important health implications particularly for the unskilled workers in the restructured mills.
BACKGROUND: Intravascular ultrasound (IVUS) is the generic name for any ultrasound technology used in vivo within the blood vessels. More specifically, intracoronary ultrasound enables imaging of the coronary arteries from within the lumen. This review concentrates on the role of intracoronary ultrasound as an adjunct to interventional cardiology. OBJECTIVES: (1) To identify the literature on IVUS for guiding coronary interventions, and to synthesise evidence about outcomes compared with outcomes when IVUS guidance has not been used. (2) To use this evidence, together with other information about costs and outcomes, to model the cost effectiveness of IVUS guidance. (3) To synthesise the evidence on the reproducibility of measurements of cross-sectional area made using IVUS. METHODS DATA SOURCES: (1) Electronic searches of MEDLINE, EMBASE, Science Citation Index, Index to Scientific and Technical Proceedings, Engineering Compendex, Engineering Page One, Cochrane Library, Inside (British Library), 1990-98. (2) Contacting experts and centres of expertise, 1990-99. (3) Internet search, 1990-99. METHODS STUDY SELECTION: Studies of IVUS-guided coronary interventions performed on humans were included in the review. Non-English language studies were also included when they covered IVUS-guided stenting or angioplasty. Control evidence regarding outcomes without IVUS guidance was sought only from randomised controlled trials (RCTs). Studies investigating the reproducibility of measurements of cross-sectional area were included only if the results were expressed in terms of the mean and standard deviation of paired differences. METHODS DATA EXTRACTION: Checklists that covered study details, patient characteristics and results were completed independently by three reviewers. Consensus was reached on any disagreements. Local data were gathered on the costs of IVUS-guided stenting. METHODS DATA SYNTHESIS: Overall event rates were calculated by pooling patient results from the included studies. A decision-analytic model was used to combine information from the literature with cost estimates, in order to predict cost-effectiveness in terms of cost per restenosis event avoided by the use of IVUS guidance. The analysis was performed from the perspective of the healthcare provider. Sensitivity analysis was undertaken. A simple extrapolation was made to long-term outcome so that cost-utility (using quality-adjusted life years (QALYs)) could be estimated. The minimum detectable change in cross-sectional area was estimated from the reproducibility results. RESULTS: Only one study on IVUS-guided angioplasty satisfied the inclusion criteria, and there were no studies on IVUS-guided atherectomy or other IVUS-guided interventions that satisfied the inclusion criteria. Of the 15 articles on IVUS-guided stenting that satisfied the inclusion criteria, seven presented data on outcomes at 6 months post-intervention. The angiographic restenosis rate was 16 +/- 1%. This compared with 24 +/- 2% derived from five articles on stenting without IVUS guidance. Data for follow-up periods longer than 6 months were presented in only two studies. Data from a total of five studies were included in the decision-analytic model. The cost per restenosis event avoided was 1545 pound sterling. After extrapolation to long-term outcome, the calculated cost per QALY was 6438 pound sterling. The baseline QALY gain was only 0.03 years. Sensitivity analysis resulted in large differences between the best- and worst-case scenarios, for example, from a saving of 5000 pound sterling to a cost of 24,000 pound sterling restenosis event avoided. The smallest changes in cross-sectional area that could be measured were 1.6 mm2 by a single observer and 1.9 mm2 by different observers. CONCLUSIONS: Implications for healthcare: The evidence available is too weak for there to be any reliable implications for clinical practice. (ABSTRACT TRUNCATED)
There is accumulating evidence that apolipoprotein E (apoE) plays a role in regulating the response to and outcome following brain injury. The present study compared the histological outcome and recovery following an episode of global ischaemia in apoE-deficient mice and wild-type littermates (12-week-old males, n = 8 per group). Transient global ischaemia was induced for a period of 17 min and the animals were allowed to recover for 72 h. Transient global ischaemia induced selective neuronal degeneration in several brain regions in wild-type mice. There was statistically significant increased ischaemic neuronal damage in apoE-deficient mice compared with wild-type mice in six of the seven regions examined (hippocampal regions CA1, CA3/CA4 and dentate gyrus; thalamus; cortex and caudate nucleus; P < 0.05). The data substantiate a role for apoE in modifying the response of the CNS to acute injury.