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Biomedical subjects

M Wood

Publications and source records attributed to M Wood.

At least 19 recordsLinked to original sources
PubMed2008

Outcome of retinoblastoma in east Africa.

We estimated the proportion of patients reaching a pediatric ophthalmology unit (Comprehensive Community Based Rehabilitation for Tanzania Disability Hospital, CCBRT) or an oncology unit (ORCI) in east Africa and investigated presentation, histology, and treatment outcomes of patients with retinoblastoma. A 5-year retrospective study identified 91 patients, representing approximately 18% of the nationwide total. Mean lag time was 10 months (standard deviation (SD) = 17) and mean follow-up was 8 months (SD = 11, range 0-40, n = 91). Thirty months disease-free survival probability was 0.23 (standard error = 0.07). Outcomes for retinoblastoma in Africa remain poor. The data presented here suggest strategies for improving the outcomes, including encouraging earlier presentation and establishment of multi-disciplinary treatment centers.

Child, Preschool↗
PubMed2006

Ensembl 2007.

The Ensembl (http://www.ensembl.org/) project provides a comprehensive and integrated source of annotation of chordate genome sequences. Over the past year the number of genomes available from Ensembl has increased from 15 to 33, with the addition of sites for the mammalian genomes of elephant, rabbit, armadillo, tenrec, platypus, pig, cat, bush baby, common shrew, microbat and european hedgehog; the fish genomes of stickleback and medaka and the second example of the genomes of the sea squirt (Ciona savignyi) and the mosquito (Aedes aegypti). Some of the major features added during the year include the first complete gene sets for genomes with low-sequence coverage, the introduction of new strain variation data and the introduction of new orthology/paralog annotations based on gene trees.

Animals↗
PubMed2006

High resolution structure of BipD: an invasion protein associated with the type III secretion system of Burkholderia pseudomallei.

Burkoldheria pseudomallei is a Gram-negative bacterium that possesses a protein secretion system similar to those found in Salmonella and Shigella. Recent work has indicated that the protein encoded by the BipD gene of B. pseudomallei is an important secreted virulence factor. BipD is similar in sequence to IpaD from Shigella and SipD from Salmonella and is therefore likely to be a translocator protein in the type-III secretion system of B. pseudomallei. The crystal structure of BipD has been solved at a resolution of 2.1 A revealing the detailed tertiary fold of the molecule. The overall structure is appreciably extended and consists of a bundle of antiparallel alpha-helical segments with two small beta-sheet regions. The longest helices of the molecule form a four-helix bundle and most of the remaining secondary structure elements (three helices and two three-stranded beta-sheets) are formed by the region linking the last two helices of the four-helix bundle. The structure suggests that the biologically active form of the molecule may be a dimer formed by contacts involving the C-terminal alpha-helix, which is the most strongly conserved part of the protein. Comparison of the structure of BipD with immunological and other data for IpaD indicates that the C-terminal alpha-helix is also involved in contacts with other proteins that form the translocon.

Amino Acid Sequence↗
PubMed2006

Crystallization and preliminary X-ray diffraction analysis of BipD, a virulence factor from Burkholderia pseudomallei.

Burkholderia pseudomallei, the causative agent of melioidosis, possesses a protein-secretion apparatus that is similar to those found in Salmonella and Shigella. A major function of these secretion systems is to secrete virulence-associated proteins into target cells of the host organism. The BipD gene of B. pseudomallei encodes a secreted virulence factor that is similar in sequence and most likely functionally analogous to IpaD from Shigella and SipD from Salmonella. Thus, the BipD protein is likely to be a component of a type III protein-secretion system (TTSS) in B. pseudomallei. Proteins in the same class as BipD, such as IpaD and SipD, are thought to act as extracellular chaperones to help the hydrophobic translocator proteins enter the target cell membrane, where they form a pore and might even link the translocon pore with the secretion needle. There is evidence that the translocator proteins also bind an integrin which stimulates actin-mediated insertion of the bacterium into the host-cell membrane. Native BipD has been crystallized in a monoclinic crystal form that diffracts X-rays to 2.5 angstroms resolution. BipD protein which incorporates selenomethionine (SeMet-BipD) has also been expressed and forms crystals which diffract to a higher resolution of 2.1 angstroms.

Bacterial Proteins↗
PubMed2006

Operating conditions for ocular surgery under general anaesthesia: an eccentric problem.

PURPOSE: To describe and examine the observation that eccentric eye positions may develop under certain general anaesthetic conditions and negatively impact upon operating conditions during ocular surgery. METHODS: A case series description with historical review followed by a 2-week prospective observational survey examining the general anaesthetic techniques utilized during ocular surgery and the associated development of an eccentric eye position. RESULTS: A total of 52 cases were studied, of which four developed eccentric eye positions. 50% of patients received effective muscle relaxation. Without muscle relaxants, the incidence of eccentric eye positioning was 18%. CONCLUSIONS: Eccentric ocular positions are likely to occur in light planes of general anaesthesia. In the case of ocular surgery, this phenomenon may create surgical difficulty and increase the risk of complication and patient morbidity. Arguments for the planned use of balanced general anaesthesia with non-depolarizing muscle relaxants are presented.

Anesthesia, General↗
PubMed2005

Fatty acid metabolism in human preimplantation embryos.

BACKGROUND: Little is known of fatty acid metabolism in human embryos. This information would be useful in developing metabolic tests of embryo quality and improving embryo culture media. METHODS: The fatty acid composition of human embryos and their ability to accumulate 13C labelled fatty acids was assessed in relation to the stage of development using gas-chromatography and combustion-isotope-ratio-mass spectrometry. RESULTS: Compared with embryos which did not develop beyond the 4-cell stage, those that did had significantly higher concentrations of the unsaturates, linoleic (12% versus 3%; P=0.02) and oleic (14% versus 7%; P=0.02), and a lower concentration of total saturates (62% versus 77%; P=0.04). There was uptake of both 13C linoleic and palmitic, but the developmental pattern was different for each fatty acid. The net accumulation in pmol/embryo/24h for palmitic was 1 at the 2-cell to <8-cell stage, 4 at the 8-cell-morula stage and negligible at the blastocyst stage. For linoleic, there was little net accumulation at the 2-cell to <8-cell stage, 8 (8-cell-morula stage) and 17 pmol/embryo/24 h (blastocyst stage). CONCLUSION: Preimplantation human embryos actively take up individual fatty acids at different rates at different stages of development. The high unsaturated concentration at the later stages of development may be explained by preferential uptake of linoleic acid.

Biological Transport↗
PubMed2005

Hormonal regulation of hepatic organic anion transporting polypeptides.

Organic anion transporting polypeptides (Oatp) mediate the transport of a wide variety of amphipathic organic substrates. Rat Oatp1b2 and human OATP1B3 are members of a liver-specific subfamily of Oatps/OATPs. We investigated whether prolactin (PRL) and growth hormone (GH) regulated Oatp1b2 and OATP1B3 gene expression via signal transducers and activators of transcription 5 (Stat5). Binding sites for Stat5 transcription factors were located in the promoters of Oatp1b2 and OATP1B3 at -209 to -201 (5'-TTCTGGGAA-3') and -170 to -162 (5'-TTCTGAGAA-3'), respectively. In primary hepatocytes from female and male rats treated with PRL or GH, Oatp1b2 mRNA measured by real-time polymerase chain reaction was significantly induced 2-fold. HepG2 cells were transiently transfected with expression vectors containing Oatp1b2 or OATP1B3 promoter fragments, cDNAs for Stat5a, and the receptors for PRL (PRLR(L)) or GH (GHR), and treated with PRL or GH. PRL and GH induction of Oatp1b2 and OATP1B3 promoter activity required cotransfection of Stat5a and PRLR(L) or GHR. Mutation of the Stat5 binding site in both promoters eliminated hormonal induction. In DNA binding assays, HepG2 cells transfected with cDNAs for Stat5a and PRLR(L) were treated with PRL, and nuclear extracts were probed with a (32)P-labeled oligomer corresponding to -177 to -157 of the OATP1B3 promoter. PRL enhanced the binding of Stat5a to the OATP1B3 promoter and DNA-protein binding was inhibited in competition assays by excess OATP1B3 and Stat5 consensus oligomers but not by mutant Stat5 oligomers. These findings indicate that PRL and GH can regulate Oatp1b2 and OATP1B3 gene expression via the Stat5 signal-transduction pathway.

Animals↗
PubMed2005

Cavernous haemangioma presenting with obstructive hydrocephalus.

With the development of MRI, the natural history of cavernous haemangiomas has been appreciated. This article describes a series of patients with deep cavernous haemangiomas who have presented with acute hydrocephalus. The diagnosis and treatment options are discussed with a review of the literature.

Adult↗
PubMed2005

Primary open-angle glaucoma presentation at a tertiary unit in Africa: intraocular pressure levels and visual status.

AIM: To investigate the presentation of POAG at a tertiary referral hospital in East Africa, including intraocular pressures, visual status and management decisions. METHODS: Retrospective review of first-time presenters with POAG over a 6-month period. RESULTS: Of the 298 patients identified, mean age 57 years (n = 296, range = 14-88, SD = 14), 213 (72%) male, 122 (41%) had normal vision (using WHO better eye acuity criteria: visual impairment < 6/18, blind < 3/60) at presentation, 87 (30%) had visual impairment and 86 (29%) were blind. The mean presenting IOP was 32 mmHg (SD = 11) and 70% of the patients had a cup:disc ratio of 0.8 or worse in the better eye. Longer disease duration (OR = 1.20, 95% CI 1.04-1.39) and higher mean IOP (OR = 1.06, 95% CI 1.02-1.10) were associated with visual impairment or blindness. Intraocular pressure showed a negative linear correlation with presenting logMAR acuity (R(2) = 0.115, SE = 1.30, p < 0.0005). The mean IOP in eyes that had undergone trabeculectomy (19 mmHg, SD = 8, n = 17) was significantly (p < 0.0005) lower than that in eyes that had not (34 mmHg, SD = 12, n = 274). The referral rate for trabeculectomy was 158/275 (57%). Male sex (OR = 2.17, 95% CI 1.0-4.72), higher mean IOP (OR = 1.09, 95% CI 1.05-1.14) and not being blind (OR = 26.47, 95% CI 9.90-70.78) were associated with surgical referral. Of the 158 patients, 76 (48%) accepted surgery. CONCLUSIONS: A high proportion of patients presenting to our unit with POAG are visually impaired or blind and the higher their presenting IOP the poorer their visual acuity. Previous trabeculectomy was associated with lower IOPs and protection from visual impairment and blindness. Further training of clinic staff towards early surgical referral and investigation of gender barriers is required.

Adolescent↗
PubMed2004

Determination of aconitine in body fluids by LC-MS-MS.

A very sensitive and specific method was developed for the determination of aconitine, the main toxic alkaloid from plants of the genus Aconitum L., in biological samples. The method comprised solid-phase extraction using mixed-mode Cs cation exchange columns followed by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Chromatographic separation was achieved with a RP8 column. Detection of aconitine was achieved using electrospray in the positive ionisation mode and quantification was performed using multiple reaction monitoring with m/z 646.4 as precursor ion, i.e. [M+H]+ of aconitine and m/z 586.5, m/z 526.4 and m/z 368.4 as product ions after collision-induced dissociation. The method was fully validated for the analysis of blood samples: the limit of detection and the limit of quantitation were 0.1 ng/g and 0.5 ng/g, respectively. Within the linear calibration range of 0.5-25 ng/g, analytical recovery was 79.9%. In two fatal cases with suspected aconite intoxication, aconitine could be detected in blood samples at concentrations of 10.0 and 12.1 ng/g. In one case, aconitine could also be detected in the stomach content (3 ng/g) and in the other in the urine (180 ng/ml).

Aconitine↗
PubMed2004

Intra-arterial delivery of endostatin gene to brain tumors prolongs survival and alters tumor vessel ultrastructure.

Glioblastoma multiforme (GBM) is an incurable malignant brain tumor, usually fatal within 1 year of diagnosis. Using a syngeneic rat 9L gliosarcoma model, we have developed a novel drug delivery method in which naked plasmid DNA is selectively targeted to brain tumors via intra-arterial injection. Using a plasmid encoding the antiangiogenic endostatin, transgene expression can be detected in tumor cells in vivo, and therapeutic efficacy is observed. Administration of this plasmid resulted in an 80% tumor volume reduction 1 week after treatment and enhanced survival time by up to 47%. Treated tumors exhibited a 40% decrease in the number of tumor vessels; ultrastructural analysis of remaining tumor vessels demonstrated a number of changes including markedly narrowed or collapsed lumens. We conclude that intra-arterial injection of plasmids selectively targets therapeutic genes to CNS neoplasms. This method of gene therapy holds promise for the treatment of these highly malignant brain tumors.

Animals↗
PubMed2003

Ocular transfer of retinal glial cells transduced ex vivo with adenovirus expressing viral IL-10 or CTLA4-Ig inhibits experimental autoimmune uveoretinitis.

Gene transfer using immunomodulatory molecules is a promising tool for in vivo regulation of immune responses. Experimental autoimmune uveitis (EAU), which serves as a model for human ocular inflammation, is induced by systemic immunization with autoantigens, but its expression is restricted to the eye. Previously, we reported protection of rodents against EAU by intravenous or/and periocular injection of vIL-10-expressing adenovirus. Here, the expression of vIL-10 was targeted into the rat Lewis eye, by intravitreal injection of either the free virus or ex vivo transfected retinal Müller glial cells (RMG-vIL-10). As shown using GFP-expressing adenovirus, a longer expression of transgene was observed in the eye after transfer of transfected syngeneic RMG cells than was seen after injection of free virus. Intravitreal injection of RMG-vIL-10 led to significant decrease in ocular pathological manifestations, compared to control RMG cells. This was observed when cells were injected simultaneously with autoantigen, but also after a delayed administration of transfected cells. Finally, injection of RMG cells transfected with adenovirus expressing CTLA4 had a strongly protective effect. In conclusion, inhibition of antigen presentation at the site of expression of the autoimmune disorders represents an attractive alternative to treat ocular inflammation, and the transfer of ex vivo genetically modified cells provides a promising method to target the factor of interest into the eye.

Abatacept↗
PubMed2003

Development of a rapid and sensitive method for the quantitation of amphetamines in human plasma and oral fluid by LC-MS-MS.

Target analysis of amphetamines in biological samples is of great importance for clinical and forensic toxicologists alike. At present, most laboratories analyze such samples by gas chromatography-mass spectrometry. However, this procedure is labor-intensive and time-consuming, particularly as a preliminary extraction and derivatization are usually unavoidable. Here we describe the development of an alternative method. Amphetamines were isolated from human plasma and oral fluid using a simple methanol precipitation step and subsequently analyzed using reversed-phase liquid chromatography-tandem mass spectrometry. Quantitation of the drugs was performed using multiple reaction monitoring. The developed method, which requires only 50 microL of biological sample, has a total analysis time of less than 20 min (including sample preparation) and enables the simultaneous quantitation of 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, amphetamine, methamphetamine, and ephedrine in a single chromatographic run. Limits of detection of 2 microg/L or better were obtained. The method has been validated and subsequently applied to the analysis of plasma and oral fluid samples collected from current drug users.

3,4-Methylenedioxyamphetamine↗
PubMed2003

Development of a rapid and sensitive method for the quantitation of benzodiazepines in Calliphora vicina larvae and puparia by LC-MS-MS.

Liquid chromatography-tandem mass spectrometry (LC-MS-MS) is emerging as the tool of choice for rapid analysis and the detection of biologically active compounds in complex mixtures. We describe the development of a sensitive method for the simultaneous quantitation of 10 benzodiazepines in Calliphora vicina (Diptera: Calliphoridae) larvae and puparia. The use of larvae for toxicological analyses offers some technical advantages over putrefied tissue. Four sample pretreatment methods for isolating the benzodiazepines out of larvae were evaluated. A simple homogenization, followed by acetonitrile precipitation yielded the highest recoveries. Puparia were pulverized and extracted by ultrasonification in methanol. All extracts were subsequently analyzed using reversed-phase LC-MS-MS. Larvae and puparia calibrators containing benzodiazepines at concentrations ranging from 25 to 750 pg/mg and 50 to 500 pg/mg, respectively, were prepared and analyzed. The method was demonstrated to be linear over the ranges investigated. Limits of detection were from 1.88 to 5.13 pg/mg larva and from 6.28 to 19.03 pg/mg puparium. The developed method was applied to the determination of nordiazepam and its metabolite oxazepam in larvae and puparia of the Calliphora vicina fly that had been reared on artificial foodstuff (beef heart) spiked with 1 microg/g nordiazepam. The larvae were harvested at day 5 for analysis of drug content. The method was sufficiently sensitive to allow the detection of nordiazepam and oxazepam in a single larva or puparium.

Animals↗
PubMed2003

Sex-based differences in serum cardiac troponin I, a specific marker for myocardial injury, after cardiac surgery.

BACKGROUND: Prevalence and causes of sex-based differences in morbidity and mortality secondary to cardiovascular disease remain controversial. Cardiac troponin I (cTnI) is a sensitive and specific marker for myocardial injury. Serial cTnI measurements have been used to identify perioperative myocardial cell injury. OBJECTIVE: To determine whether sex influences the extent of myocardial injury during cardiac surgery, we measured perioperative cTnI in male and female patients. DESIGN: A total of 17 male and 17 female patients were prospectively studied in an age- and case-matched manner. Arterial cTnI were obtained preinduction, 30 mins after the application of the aortic cross-clamp, at arrival to the intensive care unit, and on postoperative day 1. SETTING: Tertiary cardiac surgery center at a major teaching hospital. RESULTS: There was no difference between men and women in body mass index (kg/m2), duration of cardiopulmonary bypass, and aortic cross-clamp times. Preoperative cTnI measurements were similar in men (0.24 +/- 0.15 ng/mL) and women (0.25 +/- 0.13 ng/mL, mean +/- sem). The maximum serum cTnI occurred on postoperative day 1 in all patients, and it was 3-fold higher in men (18.5 +/- 5.7 ng/mL) compared with women (6.4 +/- 1.0 ng/mL). CONCLUSIONS: Men had markedly higher serum cTnI compared with women, although they were case matched with respect to age and cardiac risk factors. Our results may suggest there may be sex-related differences in the myocardial response to ischemia and reperfusion injury or intrinsic differences between the male and female myocardium.

Aged↗