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Biomedical subjects

M Wright

Publications and source records attributed to M Wright.

At least 109 records · Page 6Linked to original sources
PubMed1998

Effect of acute exercise on plasma homocysteine.

BACKGROUND: The aim this work was to study the effects of acute exercise on plasma homocysteine level. METHODS: Twenty healthy, physically active males aged 24-39 (X = 29) ran on treadmill at an intensity of 70% of their maximal heart for 30 minutes. Blood was taken before, immediately following and 30 minutes following the exercise bout. RESULTS: There was no statistically significant relationship between pre-exercise plasma homocysteine levels and VO2 max (r = -0.05). Plasma homocysteine significantly increased 11.5% from the pre-exercise to 11.6 +/- 3.3 mumol.L-1 immediate post exercise levels. Thirty minutes postexercise plasma homocysteine was still elevated from pre-exercise levels, however the mean of 11.2 +/- 2.9 mumol.L-1 was not statistically different from pre-exercise values. The increase in homocysteine that occurred with 30 minutes of exercise is thought to be the result of hemoconcentration as indicated by changes in plasma albumin. Plasma albumin likewise paralleled the changes observed for homocysteine. Mean pre-exercise plasma albumin values were 42.9 +/- 2.9 g.L-1. Plasma albumin significantly increased 6.9% to 45.8 +/- 2.4 g.L-1 immediately post-exercise. Thirty minutes post exercise plasma albumin was still elevated from pre-exercise levels at 44.8 +/- 5.4 g.L-1. When the homocysteine plasma levels were adjusted for changes in plasma albumin, there was no statistical difference between any of the time points. CONCLUSIONS: It was concluded that acute exercise does not have any effect on plasma homocysteine in young healthy men aged 24-39.

Adult↗
PubMed1997

A novel gene therapy strategy for elimination of prostate carcinoma cells from human bone marrow.

We report a novel means to purge bone marrow of a specific subset of prostate carcinoma cells based on transductional and genetic selectivity. Using both adenovirus-polylysine-DNA complexes and E1A/B-deleted replication-deficient adenoviruses, we have demonstrated a transductional preference of these vectors for the prostate carcinoma cell lines DU 145, LNCaP, and PC-3 over primary human bone marrow cells and the leukemia cell line KG-1. We have also shown a genetic selectivity of an anti-erbB-2 intracellular single-chain antibody (sFv) encoding adenovirus, Ad21, for the erbB-2-positive prostate carcinoma cell lines DU 145 and LNCaP. Delivery of Ad21 resulted in cytotoxicity to the DU 145 and LNCaP, but not PC-3, cell lines and reduced the clonogenic capacity of DU 145 cells cultured alone or mixed with various ratios of irradiated human bone marrow. Finally, quantitative, competitive reverse transcription polymerase chain reaction (QC-RT-PCR) analysis demonstrated that Ad21 could effectively reduce DU 145 and erbB-2-positive primary prostate tumor contamination in bone marrow cultures. Delivery of Ad21 had no effect on the ability of progenitor cells to form colonies. These results suggest that an anti-erbB-2 sFv-encoding adenoviral vector is efficacious for removal of erbB-2-positive prostate carcinoma cells from human bone marrow, and demonstrates a novel method for ex vivo genetic purge of malignant cells from bone marrow for autologous bone marrow transplantation (ABMT) therapy.

Adenoviridae↗
PubMed1997

Protein complexes containing gamma-tubulin are present in mammalian brain microtubule protein preparations.

The presence of gamma-tubulin in microtubule preparations, obtained by disassembly/ assembly cycles at 0degreesC/37degreesC from the brain of several mammals, is demonstrated by immunoblotting with specific antibodies directed against three distinct regions of the protein. In contrast gamma-tubulin was absent from pure tubulin obtained by chromatography on phosphocellulose, but was retained on the column with the other microtubule-associated proteins. A large part of the gamma-tubulin was present in cold stable material remaining after microtubule disassembly at OdegreesC and was partially solubilized using high salt, thus preventing its purification by the usual assembly/disassembly procedure used for alpha/beta-tubulin heterodimers. Brain gamma-tubulin was purified by affinity chromatography with gamma-tubulin antibodies raised against its carboxyl terminal region. Purified gamma-tubulin consisted of at least two polypeptides present in equal quantities and exhibiting a pI of 6.5 and 6.6, respectively. It was associated with the alpha/beta-tubulin heterodimer and with at least five other polypeptides of 75, 105, 130, 195, and 250 kDa. With the exception of the 250 kDa polypeptide, all of these proteins seem to be present in gamma-tubulin complexes isolated from Xenopus eggs. But, in contrast with Xenopus egg complexes, brain complexes exhibited a considerable heterogeneity of their apparent masses and composition in sucrose gradient centrifugation, in agreement with the absence of an homogeneous structure in electron microscopy. Despite this heterogeneity, gamma-tubulin complexes bind quantitatively to microtubule extremities. The possibility to further use mammalian brain gamma-tubulin and some of its associated proteins in biochemical and pharmacological experiments is of interest since brain microtubule protein preparations have been extensively used for studying both microtubule dynamics and the activity of microtubule poisons.

Animals↗
PubMed1997

Transductional efficacy and safety of an intraperitoneally delivered adenovirus encoding an anti-erbB-2 intracellular single-chain antibody for ovarian cancer gene therapy.

We have previously shown that adenoviral-mediated delivery of an anti-erbB-2 intracellular single-chain antibody (sFv) causes specific cytotoxicy in erbB-2-overexpressing ovarian carcinoma cells. Furthermore, intraperitoneal delivery of the anti-erbB-2 sFv enhances survival and reduces tumor burden in a xenograft model of human ovarian carcinoma in SCID mice. These findings have led to an RAC-approved Phase I clinical trial for patients with ovarian cancer. In this report, we show that expression of the anti-erbB-2 sFv could be readily detected in target tumor cells by in situ hybridization methodology. PCR analysis of DNA extracted from various murine tissues demonstrated that the anti-erbB-2 sFv remained localized to the peritoneum. Delivery of the sFv to the non-erbB-2-overexpressing REN mesothelial and Hep G2 hepatocellular carcinoma cell lines was not deleterious to either one, affirming the tumor specificity of this gene therapy strategy. In addition, histopathological analysis of various tissues showed that adenoviral-mediated delivery of the anti-erbB-2 sFv to immunocompetent mice with either primary exposure or previous vector challenge at different doses produced no abnormal changes when compared to untreated animals. These findings suggest that adenoviral-mediated delivery of the anti-erbB-2 sFv in a human context can be effectively assayed, is potentially free of vector-associated toxicity, and retains biologic utility based on tumor specificity.

Adenoviridae↗
PubMed1997

Sexual orientation differences in cerebral asymmetry and in the performance of sexually dimorphic cognitive and motor tasks.

With each of the tasks in the present studies we expected to find the reported sex difference between heterosexual women and heterosexual men and we predicted a sexual orientation effect with the performance of homosexual men being similar to that of heterosexual women and different from that of heterosexual men. Study 1 aimed to replicate earlier findings by recording the performance of a group of homosexual men on a visuospatial task, the Vincent Mechanical Diagrams Test (VMDT), a dot detection divided visual field measure of functional cerebral asymmetry, and on five subtests of the Wechsler Adult Intelligence Scale (WAIS). For each task the profile of scores obtained for the homosexual men was similar to that of heterosexual women in that they scored lower than heterosexual men on the VMDT, they showed less asymmetry, and they recorded a higher Verbal than Performance IQ on the WAIS. In Study 2, a male-biased targeted throwing task favored heterosexual men while, in contrast, on the female-biased Purdue Pegboard single peg condition heterosexual men were outperformed by heterosexual women and homosexual men. On neither of these two tasks did the performances of homosexual men and heterosexual women differ. One task, manual speed, yielded neither sex nor sexual orientation differences. Another, the Purdue Pegboard assemblies condition, revealed a sex difference but no sexual orientation difference. Failure to obtain a sexual orientation difference in the presence of a sex difference suggests that the sexual orientation effect may be restricted to a subset of sexually dimorphic tasks.

Adult↗
PubMed1997

EWS/FLI1-induced manic fringe renders NIH 3T3 cells tumorigenic.

EWS/FLI1, a fusion gene found in Ewing's sarcoma, encodes a transcriptional regulator and promotes cellular transformation by modulating the transcription of specific target genes. We have found that EWS/FLI1 and structurally related fusion proteins upregulate manic fringe (MFNG), a recently described member of the Fringe gene family instrumental in somatic development. MFNG is also expressed in human tumour-derived cell lines expressing EWS/FLI1. Overexpression of MFNG in NIH 3T3 cells renders them tumorigenic in mice with severe combined immunodeficiency disease (SCID). These data demonstrate that part of the oncogenic effect of EWS/FLI1 is to transcriptionally deregulate a member of a family of morphogenic genes.

3T3 Cells↗
PubMed1997

An intracellular anti-erbB-2 single-chain antibody is specifically cytotoxic to human breast carcinoma cells overexpressing erbB-2.

We previously demonstrated that delivery of a gene encoding an anti-erbB-2 intracellular single-chain antibody (sFv) resulted in down-regulation of cell surface erbB-2 levels and induction of apoptosis in erbB-2 overexpressing ovarian cancer cells. Based upon these findings, we hypothesized that human breast carcinomas overexpressing erbB-2 would be similarly affected by this genetic intervention. We evaluated the phenotypic effects resulting from intracellular expression of the anti-erbB-2 sFv on the human breast cancer cell lines MDA-MB-361, SK-BR-3, BT-474, MCF-7 and MDA-MB-231. Recombinant adenoviruses encoding either a reporter gene (AdCMVLacZ) or the endoplasmic reticulum (ER) directed anti-erbB-2 sFv (Ad21) were delivered to various breast cancer cell lines. Cell viability was determined by a proliferation assay and fluorescent microscopy allowed visualization of apoptotic cells. An erbB-2 ELISA quantified the endogenous erbB-2 levels of each cell line. The anti-erbB-2 sFv-encoding-adenovirus, Ad21, but not the beta-galactosidase encoding adenovirus, AdCMVLacZ, was cytotoxic to > 95% of the tumor cells in the MDA-MB-361 and SK-BR-3 lines, and > 60% of the tumor cells in the BT-474 line. In marked contrast, the MCF-7 and MDA-MB-231 cell lines showed no change in the rate of cell proliferation following this treatment. The cytotoxic effects generated in the first three lines were a consequence of the induction of apoptosis by the anti-erbB-2 sFv. An ELISA specific for erbB-2 showed that the breast cancer cell lines most susceptible to the anti-erbB-2 sFv, MDA-MB-361, SK-BR-3 and BT-474, overexpressed the erbB-2 protein while the cell lines demonstrating no response to the anti-erbB-2 sFv, MCF-7 and MDA-MB-231, expressed the lowest levels of erbB-2. These results demonstrate that targeted killing of erbB-2 overexpressing cells via intracellular knockout can be accomplished in the context of breast carcinoma. Furthermore, erbB-2 levels in breast tumor cells may be predictive of their sensitivity to sFv-mediated killing. The ability to accomplish selective cytotoxicity of breast cancer cell lines overexpressing the erbB-2 tumor marker should allow for derivation of clinical gene therapy strategies for breast cancer utilizing this approach.

Adenoviridae↗
PubMed1997

Heterogeneity in intensive care units: fact or fiction?

Reports and guidelines concerning intensive care practice have been issued recently. However, the introduction of such centrally issued recommendations may be difficult because of marked heterogeneity between intensive care units. This study examined the facilities (number of beds, consultant sessions, nursing establishment), annual workload (number and types of patients admitted) and outcome (intensive care unit mortality) in the (old) Anglia Region. There were significant differences in the distribution of patients' ages, severities of illness, diagnoses, durations of admission and outcomes. Such heterogeneity may make multicentre trials more difficult to conduct and create problems when uniform measures designed to improve intensive care services are being planned.

APACHE↗
PubMed1997

Comparison of the efficacy of diclofenac and betamethasone following strabismus surgery.

AIMS: To compare the relative antiinflammatory potency and safety of topical diclofenac-gentamicin with betamethasone-neomycin following strabismus surgery. METHODS: A single centre, single observer, prospective, randomised, and double masked clinical trial of 25 children undergoing bilateral symmetrical horizontal strabismus surgery was carried out. One eye received diclofenac-gentamicin and the contralateral eye received betamethasone-neomycin; both treatments were instilled four times a day for 4 weeks postoperatively. Ocular inflammation was assessed at 1 and 4 weeks postoperatively, objectively by comparison with a photographic chart and subjectively by questionnaire. RESULTS: There was no statistically significant difference in the rate of resolution of the inflammatory response between each group at both visits. CONCLUSION: Diclofenac appears to be as effective as betamethasone in controlling postoperative inflammation following strabismus surgery and may offer a safer alternative to the use of topical steroids.

Anti-Bacterial Agents↗
PubMed1997

Strategies for antenatal detection of Down's syndrome.

AIM: To predict the effect of maternal serum screening and fetal echocardiography on the birth prevalence of Down's syndrome. METHODS: The outcome of all Down's syndrome pregnancies in the Northern Health Region between 1985 and 1991 was retrospectively ascertained. The number and outcome of all Down's syndrome pregnancies were used to define a theoretical population which would exist in the absence of screening. Published reports were used to predict the effects of screening strategies. RESULTS: Down's syndrome was identified in 412 pregnancies of which 315 (76%) resulted in live birth. A theoretical population with no antenatal screening would be expected to produce 31 stillbirths and 381 (92%) live births affected by Down's syndrome. In the same population a programme of maternal serum screening and fetal echocardiography would lead to 155 and 14 terminations, respectively, and when combined, would reduce affected live births to 229 (56%). CONCLUSIONS: Even if maternal serum screening and fetal echocardiography achieve their predicted potential, around half of all pregnancies affected by Down's syndrome will result in live born babies.

Adult↗
PubMed1997

Biotransformation of taxoids by human cytochromes P450: structure-activity relationship.

The metabolism of paclitaxel and docetaxel by human liver microsomes was investigated in vitro. The main metabolite of paclitaxel formed in vitro was the 6 alpha-hydroxypaclitaxel: its formation largely exceeded the formation of other metabolites hydroxylated on the lateral chain by rat liver microsomes and initially characterized in rat bile. In contrast, in vitro studied showed that the initial metabolite of docetaxel resulted from the hydroxylation of the tert-butyl of the lateral chain at C13 and that the same metabolites were formed in human and animal models. Comparison of individual CYP protein content of human microsomes and catalytic activities with taxoid biotransformation, showed that 2 distinct isoforms were assigned to the 6 alpha-hydroxylation (CYP2C) and to the hydroxylation of the lateral chain (CYP3A4). Chemical and immunological inhibitions confirmed these assumptions. The effect of antineoplastic drugs potentially associated with taxoids during chemotherapy has been tested in vitro on paclitaxel and docetaxel biotransformations. In the therapeutic range, vincristine, vinblastine, doxorubicine and cisplatin elicited a moderate or no inhibition of paclitaxel and docetaxel metabolism, as well as cimetidine, ranitidine and diphenylhydramine used to prevent major side effects associated with taxoid therapy. In patients given barbiturates, the hydroxylation on the lateral chain of paclitaxel and docetaxel was markedly stimulated and resulted from the induction of CYP3A isoforms. These results clearly demonstrated that the biotransformation of paclitaxel and docetaxel by human liver microsomes was supported by 2 distinct CYP proteins and that drug interactions could modify the therapeutic efficiency of taxoids during chemotherapy.

Animals↗
PubMed1996

The gene for the Ellis-van Creveld syndrome is located on chromosome 4p16.

Ellis-van Creveld syndrome (EVC) is an autosomal recessive disorder characterized by disproportionate dwarfism, polydactyly, and congenital heart disease. This rare disorder is found with increased frequency among the Old Order Amish community in Lancaster County, Pennsylvania. We have used linkage analysis to localize the gene responsible for the EVC phenotype in nine interrelated Amish pedigrees and three unrelated families from Mexico, Ecuador, and Brazil. We now report the linkage for the Ellis-van Creveld syndrome gene to markers on the distal short arm of human chromosome 4, with Zmax = 6.91 at theta = 0.02 for marker HOX7, in a region proximal to the FGFR3 gene responsible for the achondroplasia phenotype.

Brazil↗
PubMed1996

Metabolism of docetaxel by human cytochromes P450: interactions with paclitaxel and other antineoplastic drugs.

The metabolism of docetaxel by human liver microsomes was investigated in vitro and compared with that of paclitaxel. A main docetaxel metabolite was generated by human liver microsomes in the presence of NADPH: retention time in high pressure liquid chromatography and its ion fragmentation in mass spectrometry were identical to those of the authentic derivative hydroxylated at the butyl group of the C13 side chain. Kinetic measurements and chemical and immunological inhibitions demonstrated that CYP3A was implicated in the hydroxylation of docetaxel: Km (2 microM) and Vm values of docetaxel for human liver microsomes were comparable to those calculated for the formation of metabolite p-hydroxy-phenyl C3' paclitaxel (M4). Docetaxel hydroxylation correlated only with the CYP3A content of microsomes and with CYP3A-dependent 6 beta-hydroxylation of testosterone and 16-hydroxylation of dehydroepiandrosterone. The formation of hydroxydocetaxel was strongly reduced by CYP3A inhibitors such as ketoconazole, midazolam, erythromycin, testosterone, orphenadrine, and troleandomycin, whereas quinidine (CYP2D6), hexobarbital, tolbutamide, and mephenytoin (CYP2C) had no or little effect. The hydroxylation of docetaxel exhibited a highly positive correlation with the formation of metabolite M4 of paclitaxel (r = 0.929, P < 0.0001, n = 12), but not with its 6-hydroxylation (r = 0.48, P > 0.15). Docetaxel abolished the hydroxylation of paclitaxel metabolite M4, but was totally inactive on its 6 alpha-hydroxylation. Conversely, paclitaxel reduced significantly the hydroxylation of docetaxel. We examined in vitro the possible interaction among docetaxel, paclitaxel, and drugs which could be associated during chemotherapy. Cisplatin, verapamil, doxorubicin, vinblastine, and vincristine at concentrations usually recommended did not markedly modify taxoid metabolism. Ranitidine and diphenylhydramine had no effect, but 100 microM cimetidine partially inhibited the formation of 6 alpha-hydroxypaclitaxel. Pretreatment of patients with barbiturates strikingly stimulated docetaxel hydroxylation, whereas no acceleration of docetaxel hydroxylation was noticed in a patient receiving steroids.

Antineoplastic Agents, Phytogenic↗
PubMed1996

Maternal cell contamination in uncultured amniotic fluid.

The presence of maternal cells in uncultured amniotic fluid may result in error in the interpretation of prenatal tests such as direct DNA analysis and rapid aneuploidy detection by fluorescence in situ hybridization (FISH). Using simultaneous dual colour X and Y FISH, we assessed maternal cell contamination in uncultured amniotic fluids from 500 women carrying male fetuses. The presence of maternal cells was correlated with the amount of blood present in the amniotic fluid as defined by visual examination of the cell pellet after centrifugation. The overall rate of maternal cell contamination in uncultured amniotic fluid as identified using X and Y-specific probes was 21.4 per cent, compared with 0.2 per cent in cultured fluid. Sixteen per cent of slightly bloody and 55 per cent of moderately bloody uncultured fluids had at least 20 per cent maternal cells and were classified as uninformative according to our protocol for rapid aneuploidy detection. Maternal and fetal cells could not be distinguished based on morphological characteristics alone.

Amniotic Fluid↗