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Biomedical subjects

S A Harding

Publications and source records attributed to S A Harding.

At least 19 recordsLinked to original sources
PubMed2001

Long-term clinical safety and efficacy of NIROYAL vs. NIR intracoronary stent.

Research in vitro and in animal models suggested that gold electroplating of stents can attenuate neointimal hyperplasia and reduce thrombogenicity. The objective of this study was to evaluate the safety and efficacy of the gold-coated NIROYAL stent in the treatment of stenosed coronary arteries and bypass grafts. We retrospectively studied 181 consecutive patients undergoing deployment of NIR (n = 87) or NIROYAL (n = 94) coronary stents in a single tertiary referral center from July 1997 to December 1998. Mean follow-up duration for the NIR and NIROYAL patient groups were 11.6 and 11.4 (range, 3-12) months, respectively. Stent thrombosis rates were 3/87 (3%) in the NIR and 0/94 (0%) in the NIROYAL group (P = 0.07). The need for target lesion revascularization (TLR) in the NIR patient group was 8/87 (9%) compared to 11/94 (12%) in the NIROYAL patient group (P = 0.6). The overall MACE rates for the NIR and NIROYAL patient groups were 24/87 (28%) and 22/94 (23%), respectively (P = 0.5). The present study, hence, implies equivalence between the stainless steel NIR and the gold-plated NIROYAL stent with no significant difference in immediate and long-term clinical performance profiles.

Angioplasty, Balloon, Coronary↗
PubMed2001

Adjunctive pharmacotherapy for coronary stenting.

The use of coronary stents improves the outcomes of percutaneous coronary intervention (PCI). This has led to a rapid increase in their use. Coronary stenting is not without problems and is complicated by both early ischemic events and late restenosis. The combination of anticoagulation with unfractionated heparin (UFH) and the use of antiplatelet agents including aspirin, thienopyridines, and glycoprotein IIb/IIIa inhibitors has led to a major reduction in early ischemic events after stenting. Low molecular weight heparin (LMWH) and direct thrombin inhibitors have a number of theoretical advantages over UFH. Their role as an adjunct to coronary stenting is still under investigation. Trials of systemic pharmacotherapy aimed at reducing in-stent restenosis have been consistently disappointing. Preliminary results of stents coated with agents that inhibit neointimal proliferation are extremely promising. The results of ongoing phase III trials of these coated stents are eagerly awaited.

Coronary Disease↗
PubMed2001

The use of mechanical devices as adjuncts to intracoronary stenting.

A number of mechanical adjuncts to intracoronary stenting are now available to the interventional cardiologist. These devices have assisted in the development of a safer and more effective stenting practice. Intravascular ultrasound-guided stenting has been shown to reduce the rate of subacute thrombosis and subsequent restenosis. It allows a greater appreciation of lesion structure and severity so that an appropriate intervention strategy can be devised. Debulking techniques may allow the optimal deployment of stents so that restenosis is reduced; however, the results of large randomized studies are still awaited. The use of thrombectomy and distal embolization protection devices is emerging as a safer alternate to stenting alone in difficult patient subsets, such as those with thrombus-laden lesions and degenerated vein grafts. Doppler and pressure wires may be useful in determining optimal stent deployment and predict subsequent patient outcomes. An understanding of the indications and limitations of these devices is of increasing importance to the interventional cardiologist as the coming decade threatens to yield an impressive array of high-tech innovations.

Cardiac Surgical Procedures↗
PubMed2001

The last step of syringyl monolignol biosynthesis in angiosperms is regulated by a novel gene encoding sinapyl alcohol dehydrogenase.

Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) has been thought to mediate the reduction of both coniferaldehyde and sinapaldehyde into guaiacyl and syringyl monolignols in angiosperms. Here, we report the isolation of a novel aspen gene (PtSAD) encoding sinapyl alcohol dehydrogenase (SAD), which is phylogenetically distinct from aspen CAD (PtCAD). Liquid chromatography-mass spectrometry-based enzyme functional analysis and substrate level-controlled enzyme kinetics consistently demonstrated that PtSAD is sinapaldehyde specific and that PtCAD is coniferaldehyde specific. The enzymatic efficiency of PtSAD for sinapaldehyde was approximately 60 times greater than that of PtCAD. These data suggest that in addition to CAD, discrete SAD function is essential to the biosynthesis of syringyl monolignol in angiosperms. In aspen stem primary tissues, PtCAD was immunolocalized exclusively to xylem elements in which only guaiacyl lignin was deposited, whereas PtSAD was abundant in syringyl lignin-enriched phloem fiber cells. In the developing secondary stem xylem, PtCAD was most conspicuous in guaiacyl lignin-enriched vessels, but PtSAD was nearly absent from these elements and was conspicuous in fiber cells. In the context of additional protein immunolocalization and lignin histochemistry, these results suggest that the distinct CAD and SAD functions are linked spatiotemporally to the differential biosynthesis of guaiacyl and syringyl lignins in different cell types. SAD is required for the biosynthesis of syringyl lignin in angiosperms.

Acrolein↗
PubMed1999

Repression of lignin biosynthesis promotes cellulose accumulation and growth in transgenic trees.

Because lignin limits the use of wood for fiber, chemical, and energy production, strategies for its downregulation are of considerable interest. We have produced transgenic aspen (Populus tremuloides Michx.) trees in which expression of a lignin biosynthetic pathway gene Pt4CL1 encoding 4-coumarate:coenzyme A ligase (4CL) has been downregulated by antisense inhibition. Trees with suppressed Pt4CL1 expression exhibited up to a 45% reduction of lignin, but this was compensated for by a 15% increase in cellulose. As a result, the total lignin-cellulose mass remained essentially unchanged. Leaf, root, and stem growth were substantially enhanced, and structural integrity was maintained both at the cellular and whole-plant levels in the transgenic lines. Our results indicate that lignin and cellulose deposition could be regulated in a compensatory fashion, which may contribute to metabolic flexibility and a growth advantage to sustain the long-term structural integrity of woody perennials.

Cellulose↗
PubMed1999

Effect of maternal ambulation on labour with low-dose combined spinal-epidural analgesia.

Two hundred and twenty-nine nulliparous women who requested regional analgesia during labour were given a combined spinal-epidural block. They were randomly allocated to stay in bed or spend at least 20 min of every hour out of bed. There was no significant difference in duration of labour, analgesia requirements, mode of delivery or condition of the baby between the groups. Ambulation appeared to be safe for the mother and baby. Maternal satisfaction with the low-dose combined spinal-epidural was high in both groups.

Adult↗
PubMed1997

Transgenic tobacco expressing a foreign calmodulin gene shows an enhanced production of active oxygen species.

A strategy for elucidating specific molecular targets of calcium and calmodulin in plant defense responses has been developed. We have used a dominant-acting calmodulin mutant (VU-3, Lys to Arg115) to investigate the oxidative burst and nicotinamide co-enzyme fluxes after various stimuli (cellulase, harpin, incompatible bacteria, osmotic and mechanical) that elicit plant defense responses in transgenic tobacco cell cultures. VU-3 calmodulin differs from endogenous plant calmodulin in that it cannot be methylated post-translationally, and as a result it hyperactivates calmodulin-dependent NAD kinase. Cells expressing VU-3 calmodulin exhibited a stronger active oxygen burst that occurred more rapidly than in normal control cells challenged with the same stimuli. Increases in NADPH level were also greater in VU-3 cells and coincided both in timing and magnitude with development of the active oxygen species (AOS) burst. These data show that calmodulin is a target of calcium fluxes in response to elicitor or environmental stress, and provide the first evidence that plant NAD kinase may be a downstream target which potentiates AOS production by altering NAD(H)/NADP(H) homeostasis.

Calcium↗
PubMed1997

Use of heparinase modified thrombelastography in liver transplantation.

Severe coagulopathies can occur during liver transplantation, particularly after reperfusion of the grafted liver. Heparin release has been proposed as one of the factors contributing to this coagulopathy. We have analysed the thrombelastograph (TEG) traces of 55 patients after reperfusion using native and heparinase-treated samples. In almost all cases an abnormal native TEG was improved in vitro by heparinase, demonstrating the presence of heparin or a heparin-like substance. The heparinase-modified TEG allowed assessment of the underlying coagulation status, providing a rational guide to blood component replacement or treatment of fibrinolysis.

Blood Coagulation Disorders↗
PubMed1994

Meningitis after combined spinal-extradural anaesthesia in obstetrics.

We report two cases of meningitis which developed after combined spinal-extradural procedures for obstetric analgesia. The first case was thought to be caused by aseptic or chemical meningitis and the second was a case of bacterial meningitis in a patient who also received an extradural blood patch. It is important that meningitis is considered as a differential diagnosis in patients who present with headache after spinal anaesthesia and that antibiotic therapy is selected to cover unusual organisms.

Adult↗
PubMed1981

Orbital tuberculosis.

A 37-year-old man had epistaxis, headache, intermittent swelling of the periorbital region, proptosis, epiphora, and chronic sinusitis. X-ray films showed marked erosion of the midline facial bones, total opacification of both maxillary sinuses, and clouding of the sphenoid and left ethmoid sinuses. He also had a cutaneous-maxillary sinus fistula and a purulent discharge. A histopathologic examination disclosed areas of acute and chronic inflammation with occasional noncaseating granulomas. Biopsy specimens and postoperative sputum cultures grew Mycobacterium tuberculosis, although the patient had no obvious signs of systemic disease. Because tuberculosis of the orbit is rare in developed countries, it is often overlooked in the diagnosis of granulomatous inflammation of the orbit. This can lead to exacerbation of the disease by corticosteroid treatment.

Adult↗
PubMed1981

Radiation dermatitis: a case report.

A unique form of vasculitis occurring six months after radiation therapy for postoperative breast cancer is described herein. This rare, unexplainable reaction is a very unusual occurrence.

Aged↗
PubMed1980

Detection of circulating antigen in experimental Candida albicans endocarditis by an enzyme-linked immunosorbent assay.

A double-antibody sandwich enzyme-linked immunosorbent assay was developed for the detection of circulating Candida albicans antigen during the course of experimental C. albicans endocarditis. The enzyme-linked immunosorbent assay was positive in 75% of rabbits with polyethylene catheter-induced experimental aortic valve C. albicans endocarditis but was negative in all controls, including catheterized animals that received intravenous Candida or catheterized but uninfected animals, and in rabbits with experimental fungal or bacterial endocarditis of other etiologies. The enzyme-linked immunosorbent assay was much more sensitive than blood culturing or fever determinations in experimental C. albicans endocarditis. This assay is more sensitive than currently available serological techniques, is highly specific, and deserves further study in the diagnosis of invasive, disseminated C. albicans infections, including endocarditis.

Animals↗