Biomedical subjects
Publications and source records attributed to P Gaffney.
This paper concerns users' views on computerised resources. The focus concerns a software tool that could be used to allow safety conscious user manipulation of the combination of these computerised resources. It is of concern to the authors that computerised resources used in healthcare should reflect users' working practices rather than working practices being changed to reflect computerised resources.
The use of lipid-lowering drugs has been shown to have beneficial effects in primary and secondary prevention of cardiovascular disease. Gemfibrozil has shown beneficial effects as a lipid lowering agent; however, some proactivating effects on platelet function in vitro have been described. We have studied in a porcine model of atherosclerosis if gemfibrozil could prevent the early vascular effects of a cholesterol-rich diet without inducing platelet activation and, hence, mural thrombosis. Pigs were fed for 50 days with a diet rich in saturated fat and cholesterol (cho). The longitudinal follow-up study showed that in control animals LDL-cho increased significantly up to 181.9 +/- 34.2 mg/dl or 79% of total-cho, while HDL-cho was reduced to 19% of total-cho. Gemfibrozil, at average therapeutic plasma levels (peak levels of 28 micrograms/ml) [corrected], induced a significant reduction in the relative amount of LDL (P < 0.05) and increased HDL (P < 0.05). The increase in fibrinogen plasma levels observed in the control group due to the dietary intervention (+25%) was prevented in the treated animals (-5%). In treated animals, vascular lesions were significantly less severe, platelet deposition upon exposure of damaged vessel wall was unchanged and the fibrin layer deposited on the damaged vessel wall was significantly reduced over control animal values. This short term pharmacologic lipid lowering intervention has been able to slow down lesion development and to reduce fibrin formation onto lesioned disrupted vascular substrates without increasing platelet mural thrombosis.
BACKGROUND: The activation of protein kinase B (PKB, also known as c-Akt) is stimulated by insulin or growth factors and results from its phosphorylation at Thr308 and Ser473. We recently identified a protein kinase, termed PDK1, that phosphorylates PKB at Thr308 only in the presence of lipid vesicles containing phosphatidylinositol 3,4,5-trisphosphate (Ptdlns(3,4,5)P3) or phosphatidylinositol 3,4-bisphosphate (Ptdlns(3,4)P2). RESULTS: We have cloned and sequenced human PDK1. The 556-residue monomeric enzyme comprises a catalytic domain that is most similar to the PKA, PKB and PKC subfamily of protein kinases and a carboxy-terminal pleckstrin homology (PH) domain. The PDK1 gene is located on human chromosome 16p13.3 and is expressed ubiquitously in human tissues. Human PDK1 is homologous to the Drosophila protein kinase DSTPK61, which has been implicated in the regulation of sex differentiation, oogenesis and spermatogenesis. Expressed PDK1 and DSTPK61 phosphorylated Thr308 of PKB alpha only in the presence of Ptdlns(3,4,5)P3 or Ptdlns(3,4)P2. Overexpression of PDK1 in 293 cells activated PKB alpha and potentiated the IGF1-induced phosphorylation of PKB alpha at Thr308. Experiments in which the PH domains of either PDK1 or PKB alpha were deleted indicated that the binding of Ptdlns(3,4,5)P3 or Ptdlns(3,4)P2 to PKB alpha is required for phosphorylation and activation by PDK1. IGF1 stimulation of 293 cells did not affect the activity or phosphorylation of PDK1. CONCLUSIONS: PDK1 is likely to mediate the activation of PKB by insulin or growth factors. DSTPK61 is a Drosophila homologue of PDK1. The effect of Ptdlns(3,4,5)P3/Ptdlns(3,4)P2 in the activation of PKB alpha is at least partly substrate directed.
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The advanced instrument workstation (AIW) is one of a number of system modules developed in the OpenLabs project, offering advanced services that complement the basic services available from laboratory information systems (LIS) in general. The AIW services relate to instrument interfacing, user interfacing, quality control, calibration verification, patient result validation, local and remote fault diagnosis and maintenance, and external quality assessment (EQA) by external organisations.
In the past decade, great technological progress has been made in telemaintenance of mainframe and mini computers. As hardware technology is now available at an acceptable cost, computer aided trouble-shooting can be adapted to laboratory instrumentation in order to significantly improve repair time, avoid instrument downtime by taking advantage of predictive methods, and provide general diagnostic assistance. Depending on the size of the instrument, the telemaintenance facility can be dedicated to a single instrument or alternatively a telemaintenance server can manage multiple distributed small instruments through a Local Area Network. As complex failures can occur, the local diagnosis capabilities may be exceeded and automatic dialing for connection to computerized Remote Maintenance Centers is needed. The main advantages of such a centre, as compared to local diagnosis systems, are the increased access to more information and experience of failures from instrument installations, and consequently the provision of training data updates for Artificial Neural Networks and Knowledge Based Systems in general. When an abnormal situation is detected or anticipated by a diagnosis module, an automatic alert is given to the user, local diagnosis is activated, and for simple solutions, instructions are given to the operator. In the last resort, a human expert can be alerted who, with remote control tools, can attend to the failures. For both local and remote trouble-shooting, the data provided by the instrument and connected workstation is of paramount importance for the efficiency and accuracy of the diagnosis. Equally, the importance of standardization of telemaintenance communication protocols is addressed.
The activity of the human erythrocyte sodium-lithium countertransport (SLC) is stable over long periods in individuals. However, it is becoming increasingly evident that the transport system is susceptible to modulation, both acutely and chronically, by various factors. In this study, the authors observed temporal variation in SLC over a period of 10 h (08.00-18.00 hours) in healthy volunteers. SLC Vmax was maximum (0 center dot 354 +/- 0.051 mmol L-1 cell-1 h-1; mean +/- SE) at 'mid-day' and significantly higher than in the morning (0 center dot 291 +/- 0 center dot 035 mmol L-1 cell, h; P < 0 center dot 010). Its value in the evening (0 center dot 316 +/- 0.042 mmol L-1 cell-1 h-1) was lower than at 'mid-day' (P < 0 center dot 045) but higher than in the morning (P < 0 center dot 037). These changes were not accompanied by any significant change in the affinity of the transporter for external sodium, Km. Changes in SLC Vmax did not correlate with the corresponding ones in either plasma cortisol or aldosterone. However, they correlated well with those in plasma renin activity, the correlation between mid-day and a.m. sets of values (r = 0 center dot 718; P = 0 center dot 019) being better than that between mid-day and p.m. (r = 0 center dot 688; P = 0 center dot 028). The authors conclude that changes in SLC occur during the day, and this need be taken into account in the planning and execution of studies involving determination of the activity of this transport system.
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Hematopoietic stem cells from adult marrow, cord blood, or fetal liver can differentiate into myeloid and lymphoid lineages. Early steps in this differentiation process are not yet fully understood. To correlate surface antigen expression with molecular events occurring during early lymphopoietic differentiation, we examined CD3 gamma, CD3 delta, and CD3 zeta gene expression in adult human CD34+ marrow progenitors and their subsets. Purification by fluorescence-activated cell sorter (FACS) was used to obtain 1) a CD34+ Lin-DR- population known to contain primitive, uncommitted progenitors; 2) CD34+/CD7+/CD2+ and 3) CD34+/CD7+/CD2+ cells expressing receptors associated with natural killer (NK) cell or T cell lineage commitment. We demonstrate that CD34+Lin-DR- cells do not contain CD3 gamma, CD3 delta, or CD3 zeta transcripts, consistent with the primitive uncommitted nature of progenitors in this cell population. Expression of the CD34+/CD7+/CD2- phenotype correlates with the transcription of CD3 zeta but not CD3 gamma or CD3 delta, a pattern of transcription observed in mature blood NK but not T cells. Expression of both CD7 and CD2 on CD34+ cells is associated with not only CD3 zeta gene transcription but also CD3 gamma and CD3 delta, a pattern found in T cells but not mature NK cells. We have identified unique patterns of mRNA transcription in phenotypically distinct lymphoid progenitors found in the marrow. These findings raise the possibility that although primitive NK and T cell progenitors share a common differentiation pathway, divergent NK and T lineage commitment steps may occur very early in lymphopoiesis. Our findings suggest that application of in vitro marrow and thymus culture techniques may be utilized to more fully describe commitment and differentiation of early lymphoid progenitors and define the role of the microenvironment in this process.
OpenLabs has four major objectives: to improve the efficiency and effectiveness of clinical laboratory services by the integration of Knowledge Based Systems (KBSs) with Laboratory Information Systems (LISs) and equipment; to provide and implement standard solutions for Electronic Data Interchange (EDI) between laboratories and other medical systems; to specify a fully Open architecture for an integrated Clinical LIS and demonstrate the integration of various KBS modules on the open architecture platform; and to demonstrate the integration of OpenLabs modules with existing LISs.
The Nambour Skin Cancer and Actinic Eye Disease Prevention Trial (the Nambour Trial) is a field trial conducted in an unselected adult population in Australia. Using a randomized 2 x 2 factorial design, the principal aim is to evaluate whether regular use of high-protection sunscreen and/or dietary supplementation with beta-carotene (30 mg daily) can alter the incidence rates of basal cell carcinomas and squamous cell carcinomas of the skin over a minimum follow-up time of 4.5 years. Changes in the incidence of solar keratoses and actinic eye disease and the rate of photoaging after intervention will also be investigated. In 1992, 1626 participants between the ages of 25 and 75 years were enrolled, all of whom had been randomly selected from residents of the southeastern Queensland township of Nambour for an earlier skin cancer prevalence survey. This paper describes the background to the trial and its design, with respect to evaluation of effects on actinic skin disease, and documents the baseline characteristics of participants recruited into the Nambour Trial.
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Posthaemorrhagic ventricular dilatation (PHVD) is thought to be due to clots from intraventricular haemorrhage obstructing cerebrospinal fluid pathways involved in reabsorption. Over 60% of infants with progressive PHVD have gone on to require surgical shunt placement. Previous treatments all have major problems. The object of this pilot study was to achieve enough fibrinolysis to restore pathways of cerebrospinal fluid reabsorption and so avoid shunt surgery. Nine preterm infants with progressive PHVD were treated with intraventricular infusion of streptokinase for 12-72 hours. All the infants survived and surgical shunting was required in only one case. A 200% increase in fibrinolytic activity was demonstrated in both ventricular and spinal fluid during streptokinase treatment. There were no cases of infection. Minor rebleeding occurred in one case and was not a serious problem. This represents the first direct therapeutic approach to the pathology of PHVD.
We have employed fast atom bombardment mass spectrometry (FAB-MS) to screen the N-linked oligosaccharides of Bowes melanoma tissue plasminogen activator (mt-PA), and recombinant t-PAs produced by Chinese hamster ovary cells (rt-PA) and by a gene-enriched melanoma cell line (rmt-PA). These studies have confirmed the published structures for rt-PA, but are not in agreement with some of the structures reported for mt-PA. In the latter glycoprotein we have identified a novel structure as the major oligosaccharide attached to Asn-184 and Asn-448. This is a biantennary oligosaccharide consisting of a fucosylated trimannosyl core to which are attached two GalNAc(1----4)GlcNAc antennae, one of which carries a sialic acid linked at the 6-position of the GalNAc. Minor constituents are sialylated on both or neither antennae. The sialylated GalNAc moiety is unique in N-linked glycoproteins. The majority of complex structures in rmt-PA contain N-acetyllactosamine moieties at both the Asn-184 and Asn-448 sites with the novel oligosaccharide occurring as a minor component at the Asn-184 site. This study demonstrates the power of mass spectrometric strategies based on high-field two-sector FAB-MS for structure elucidations of natural and recombinant glycoproteins.
Concentrations of cross linked fibrin degradation products were measured in the cerebrospinal fluid from five 'normal' preterm infants (median 102 ng/ml), four preterm infants with intraventricular haemorrhage (median 315 ng/ml), and five infants with progressive post-haemorrhagic ventricular dilatation (median 1000 ng/ml). Serial samples of cerebrospinal fluid from one infant showed a peak concentration two weeks after the haemorrhage.
The plasminogen activator in parotid saliva has recently been characterized as a tissue-type plasminogen activator (t-PA). In this study stimulated parotid saliva from 21 healthy volunteers was analysed for (a) t-PA activity using the fibrin plate assay or a bioimmunoassay coupled to the plasmin-specific chromogenic substrate S-2251, (b) t-PA antigen using an enzyme-linked immunospecific assay and (c) activity of the specific fast-acting plasminogen activator inhibitor (t-PA inhibitor) assayed by its inhibitory effect on one-chain t-PA added to the samples. In parotid saliva the median t-PA activity was 0.2 IU ml-1 (normal range 0.05-0.35 IU ml-1), but activity of free t-PA could not be demonstrated by bioimmunoassay in any sample. The mean antigen concentration of t-PA was 2.2 IU ml-1 in the 10 samples with levels above the detection limit (0.5 IU ml-1). High activity of t-PA inhibitor was demonstrated in all parotid salivas, and the mean inhibitory effect on t-PA was 13.2 IU t-PA quenched per millilitre. This study thus demonstrates a fibrinolytic system in parotid saliva characterized by high t-PA inhibitor activity and relatively low concentration of inactive, probably complex-bound, t-PA which is activated in the presence of fibrin.