Biomedical subjects
Publications and source records attributed to P Gaines.
Metallic stents have made an enormous impact on the percutaneous treatment of arterial and venous disease, allowing a range of lesions to be treated using this minimally invasive technique which was not possible previously. This article details the range of stents which are available and how these have revolutionized the treatment of vascular disease.
To facilitate the selection of cell lines expressing transfected genes of interest, a plasmid vector has been constructed that directs the co-expression of heterologous cDNAs and a 3'-positioned cassette encoding a truncated CD4 marker. An encephalomyocarditis virus internal ribosomal entry site (IRES) mediates translational initiation from this 3' cassette, and a cytomegalovirus promoter drives dicistronic transcript expression. To test the utility of this vector, a luciferase reporter gene was inserted, and this construct (pIRES-CD4t-luc) was electrotransfected into myeloid FDCW2 cells. As monitored by flow cytometry and luciferase assays, three rounds of magnetic cells sorting (MACS) yielded > or = 90% CD4t-positive cells with an average density of 17,000 CD4t molecules per cell. In ten clonal sublines analyzed, luciferase expression was uniformly high and stable over a test period of three months. Finally, a comparison of MACS- vs. FACS-based isolation of transfected cells showed two to three rapid rounds of MACS to be somewhat more effective. Thus, pIRES-CD4t should prove useful in the direct and rapid selection of relevant stably or transiently transfected cells.
Erythrocyte development has previously been shown to depend upon the expression of the lineage-restricted trans-acting factor GATA-1. Despite predicted roles for this factor during early development, GATA-1-deficient cells in chimeric mice and embryonic stem cell cultures mature to a late proerythroblast stage and express at least certain genes that normally are thought to be regulated by GATA-1 (including erythroid Krüppel-like factor [EKLF] and the erythropoietin [Epo] receptor). Opportunities to test roles for GATA-1 in erythroid gene activation in these systems therefore are limited. In the present study, in an alternate approach to test the function of GATA-1, GATA-1 has been expressed together with the Epo receptor in myeloid FDCW2 cells and the resulting effects on cytokine-dependent proliferation and erythroid gene expression have been assessed. GATA-1 expression at low levels delayed FDCW2ER cell cycle progression at the G1 phase specifically during Epo-induced mitogenesis. Upon expression of GATA-1 at increased levels, proliferation in response to Epo, interleukin-3 (IL-3), and stem cell factor was attenuated and endogenous GATA-1, EKLF and betamaj-globin gene expression was activated. Friend of GATA-1 (FOG) transcript levels also were enhanced, and ets-1 and c-mpl but not Epo receptor gene expression was induced. Finally, in FDCW2 cells expressing increased levels of GATA-1 and a carboxyl-terminally truncated Epo receptor, Epo (with respect to IL-3 as a control) was shown to markedly promote globin transcript expression. Thus, novel evidence for select hierarchical roles for GATA-1 and Epo in erythroid lineage specification is provided.
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OBJECTIVES: The effect of a plain 48-wire self-expanding flexible stent (Wallstent-Schneider (Europe) AG) on abdominal aortic aneurysms has been studied in a new animal model. METHODS: Aneurysms were created by interposing fusiform segments of glutaraldehyde-tanned bovine internal jugular vein into the infrarenal aortas of 12 Large White pigs. The first six pigs were assessed after 6 weeks by ultrasonography and arteriography; they were then sacrificed for pathological examination. Endovascular placement of the stents, 2 weeks after aneurysm creation, was performed under arteriographic control in the next six pigs. These pigs were assessed by ultrasonography and arteriography 6 weeks after stenting; they were then sacrificed for pathological examination. RESULTS: At 6 weeks the aneurysms in the first group were pulsatile with partial endothelialisation and no mural thrombus. Placement of the stent in the second group was accomplished easily. Stenting resulted in an immediate reduction in wall pulsatility of all aneurysms and thrombosis of the excluded aneurysm sac occurred in three cases. In the other three cases the pulse pressure in the sac was reduced. In all cases there was a significant reduction in maximum aneurysm diameter when measured 6 weeks after stenting. CONCLUSIONS: A pulsatile, non-thrombogenic aortic aneurysm model approaching human dimensions has been successfully developed for the study of endoprostheses prior to their clinical use. Endovascular placement of a plain, multiple-wire Wallstent was associated with reductions in aneurysm pulsatility, pulse pressure within the sac and maximum aneurysm diameter over the study period. Stenting was associated with thrombosis of the excluded aneurysm sac in 50% of cases.
One hundred and fifty consecutive patients presenting with limb-threatening ischaemia were studied prospectively to determine treatment and rehabilitation costs in the first year. Limb salvage was attempted in 104 (69%) patients but failed in 13%. Mortality at 1 year was 27%. The cost of treatment, inpatient stay, occupational therapy, physiotherapy, convalescence, disablement services, home adaptations, home care, district nursing, transportation and outpatient visits were determined for each patient. The patients were classified according to their presentation and initial treatment into five groups (number of patients) whose median management costs (interquartile range) for 12 months were: Gp 1 (23 - Revascularisation for acute ischaemia = 3970 pounds (2984-5511) Gp 2 (29) - Angioplasty for critical ischaemia = 6611 pounds (3630-10,200) Gp 3 (52) - Reconstruction for critical ischaemia = 6766 pounds (4337-9677) Gp 4 (34) - Primary amputation = 10,162 pounds (7894-13,026) Gp 5 (12) - Primary bilateral amputations = 13,848 pounds (11,440-18,056) At 1 year, there was no significant difference in the cost of managing a patient with a critically ischaemic limb by angioplasty or surgical reconstruction. The cost of revascularisation for acute ischaemia was comparatively low because these patients required minimal rehabilitation. The median cost of managing a patient following amputation was almost twice that of successful limb salvage justifying an aggressive revascularisation policy. However, justification of such a policy on economic grounds requires salvage failure episode to be minimised as they increase costs considerably.
Recombinant alphaviruses have been used as vehicles for delivery and expression of heterologous genes in mammalian, avian and insect cell lines. We have used a Sindbis replicon virus (Sinreplac) able to express the E. coli lacZ gene to compare the efficiency of transduction in one insect, six mammalian cell lines and cultured rat dorsal neurons which apparently express beta-galactosidase over a 30-day time period. Results show that different cell lines were transduced with varying degrees of efficiency and that this efficiency could be improved in some cell lines by packaging the replicon with a helper derived from a more neurovirulent strain of Sindbis.
Between 1988 and 1993, 82 patients with a median age (iq range) of 81 (73-87) years underwent thrombo-embolectomy (TE) and thrombolysis for acute lower limb ischaemia at the Royal Hallamshire Hospital, Sheffield. 28 patients (Group 1) underwent TE prior to the introduction of thrombolysis in 1991. TE with intraoperative thrombolysis (IT) as an adjunct was performed in 34 patients (Group 2) and 20 patients (Group 3) were treated using percutaneous thrombolysis (PT) in the first instance. 41 of these patients were in AF at presentation. Although 24 were on digoxin, only 4 were on warfarin. Group 3 patients were younger (p < 0.05; ANOVA) with a longer duration of ischaemia (p < 0.05; ANOVA) and had less limbs suffering a sensorimotor deficit (p = 0.007; chi 2) compared with Groups 1 and 2 which were similar in these respects. Overall mortality was 17%. Successful revascularisation was achieved in 18 (64%), 28 (82%) and 15 (75%) patients in Groups 1, 2 and 3 respectively. 14 of the 15 patients successfully treated initially by PT required further intervention in order to maintain revascularisation. Revascularisation failure was associated with the presence of a sensorimotor deficit but not associated with patient age or duration of ischaemia.
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The olfactory and visual systems of Drosophila have similar developmental origins: both derived from the eye-antennal imaginal disc. Moreover, there are commonalities in the cellular, molecular, and genetic underpinnings of their development. For example, the developmental program of both systems entails cell death, which depends upon the irregular chiasm C-roughest gene, and both systems require the lozenge gene for normal pattern formation. The rdgB (retinal degeneration B) gene is required not only for the maintenance and physiology of the visual system, but also for olfactory physiology. This gene has been shown by others to encode a phosphatidylinositol transfer protein; it is expressed both in visual and olfactory organs. The norpA gene, which encodes a phospholipase C, is also required both for phototransduction and for odorant response in one olfactory organ. Thus some genes are required in both systems; in addition, at least one olfactory gene that is apparently not expressed in the visual system may have a visual system counterpart. These and other similarities are considered in terms of the evolutionary relationship between the two systems. We conclude that analysis of the visual system is likely to provide insight into the development and function of the olfactory system, and vice versa.
Four genes expressed in the olfactory system of Drosophila melanogaster have been identified by subtractive hybridization. Two of these genes, OS-E and OS-F, are related to genes encoding moth pheromone-binding proteins. The OS-E and OS-F genes are tightly linked and are expressed in a subregion of the antenna (the primary olfactory organ). A protein sequence analysis suggests the possibility that pheromone-binding proteins are members of a larger class of proteins, extending beyond the olfactory system. The predicted product of a third gene, OS-D, shares features common to vertebrate odorant-binding proteins, but has a primary structure unlike odorant-binding proteins. The fourth gene, OS-C, encodes a novel 13-kDa protein that contains a putative nuclear import sequence and an acid-rich region. The expression patterns of these genes differ within the antenna; their transcript distributions support the notion of specialized roles for different olfactory sensilla. The functions of the OS gene products have not been demonstrated; however, the potential identification of pheromone-binding proteins in Drosophila, a species with well characterized genetics, may offer a means of analyzing the function of these molecules that is not available in other systems.
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This study investigated the effect of intravascular high intensity, low frequency catheter-delivered ultrasound on vasomotor behaviour in vivo. Catheter-delivered therapeutic ultrasound induces endothelium-independent vasodilation in vitro. To study this effect in vivo we analysed the angiograms of canine coronaries and human femoropopliteal arteries before and after ultrasound exposure. Vasomotor behaviour was studied using a computer edge detection program. We analysed the angiograms of: (1) eight canine left coronary arteries before and after ultrasound; (2) eight canine left coronaries only subjected to serial angiograms, and three canine left coronary arteries of two dogs after passing the unactivated ultrasound probe down the coronary artery infusing saline at a rate of 10-20 ml.min-1, which served as controls, and (3) eight angiographically normal human arterial sites proximal to occlusions in eight femoropopliteal arteries of patients undergoing ultrasound angioplasty for peripheral vascular disease. Vessel diameter of canine coronaries after ultrasound exposure increased from 2.3 +/- 0.3 mm to 2.8 +/- 0.3 mm (21 +/- 2.3%) (P < 0.01). There was no change in vascular diameter in controls after multiple angiograms (2.4 +/- 0.3 mm vs 2.5 +/- 0.2 mm (4.2 +/- 0.2%) (P = ns). Average vessel diameter after passage of the unactivated probe with saline infusion decreased in the left anterior descending coronary artery from 3.66 mm to 3.13 mm, and in the left circumflex coronary artery from 2.88 mm to 2.62 mm. Vessel diameter in human femoropopliteal arteries increased from 3.2 +/- 0.2 mm to 3.6 +/- 0.5 mm or by 14.3 +/- 2.9% respectively (P < 0.01) after exposure to ultrasound energy.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVES: The purpose of this study was to present follow-up data as well as short-term results on a larger clinical series of patients undergoing ultrasound angioplasty. BACKGROUND: Previous pilot studies have demonstrated the feasibility of peripheral arterial ultrasound angioplasty. METHODS: We performed percutaneous ultrasound angioplasty on 50 arterial lesions in 45 patients. Our ultrasound ablation system had a frequency of 19.5 kHz. A fixed-wire probe with 2- or 3-mm ball tips and a 3-mm over-the-wire probe were used to treat 40 femoral, 7 popliteal and 3 tibioperoneal lesions. Seventeen (34%) of the lesions were calcific. Thirty (86%) of 35 occluded segments, 0.5 to 28 cm long (mean 6.2 +/- 5.7), were recanalized. RESULTS: In the 45 patent arteries, the stenosis decreased from 94 +/- 10% to 55 +/- 23% after ultrasound angioplasty and to 12 +/- 8% after balloon angioplasty. Mechanical arterial dissections (n = 4) and perforations (n = 4) without clinical consequence occurred only with the fixed non-over-the-wire probes. No evidence of embolism or vasospasm was detected; in fact, vasodilation occurred. There were no clinical manifestations of acute reocclusion. At 24 h, ankle-brachial indexes increased by 0.23 +/- 0.21 (range -0.27 to 0.72). Six- to 12-month clinical and ankle-brachial index follow-up data for 35 patients treated with ultrasound and adjunctive balloon angioplasty were indicative of restenosis in 7 patients (20%). CONCLUSIONS: Our findings indicate that percutaneous peripheral ultrasound angioplasty 1) is useful for recanalization of fibrous, calcific and thrombotic arterial occlusions; 2) reduces arterial stenoses; and 3) has clinical and ankle-brachial index data indicative of a restenosis rate of 20% at 6 to 12 months in a small cohort of patients. A larger randomized series of patients will need to be studied to assess the impact of ultrasound ablation on restenosis.
Intraarterial thrombolytic therapy is being increasingly used in the treatment of acute limb ischaemia. When strokes occur during thrombolytic therapy treatment is usually stopped because of the suspicion of cerebral haemorrhage. If the stroke is not haemorrhagic then stopping the treatment jeopardizes the ischaemic limb. If the stroke is proven to be non-haemorrhagic on computed tomography (CT) then the thrombolytic therapy should be recommenced. We present three case histories of patients who suffered a stroke during thrombolytic therapy over a 30-month period, in whom CT confirmed non-haemorrhagic stroke and we suggest that managing the ischaemic limb with anticoagulant and thrombolytic therapy can be safe in the early period following the stroke. We also discuss the probable aetiology of the strokes and whether cardiac echocardiography should be performed in these patients.
Drosophila uses different olfactory organs at different developmental stages. The larval and adult olfactory organs are morphologically dissimilar and have different developmental origins: the antenno-maxillary complex (AMC), which houses the larval olfactory organ, is histolyzed during metamorphosis; the third antennal segment--the principal adult olfactory organ--derives from an imaginal disc. A screen for genes expressed in both larval and adult olfactory organs, but in relatively few other tissues, has been carried out. Seven enhancer trap lines showing reporter gene expression in both the larval AMC and in certain subsets of the adult antenna are described. The antennal staining pattern of one line shows a striking change over the first few days of adult life, with a time course comparable to that of the development of sexual maturity. A pronounced sexual dimorphism in antennal staining pattern is seen in another line. Some staining patterns resemble the patterns of certain classes of antennal sensilla; others show expression restricted to only a small number of cells. Some lines also show expression associated with other chemosensory organs at either the larval or adult stage, including the maxillary palps, labellum, and anterior wing margin. One line, which also shows staining in the male reproductive tract, is male sterile. The significance of these results is considered in terms of (1) the molecular organization of the olfactory system; (2) the recruitment of olfactory genes for use in two developmental contexts; (3) the sharing of genes among different sensory modalities; (4) the role of olfaction in sexual behavior; and (5) posteclosional changes in the olfactory system.