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Biomedical subjects

M Wright

Publications and source records attributed to M Wright.

At least 145 records · Page 8Linked to original sources
PubMed1995

A Sindbis virus mRNA polynucleotide vector achieves prolonged and high level heterologous gene expression in vivo.

The direct intramuscular delivery of naked plasmid DNA has been demonstrated to allow expression of encoded heterologous genes in the target myocytes. The method has been employed to elicit immunization based upon delivery of antigen encoding plasmid DNA. For application in the context of achieving anti-tumor immunization against antigenic transforming oncoproteins, delivery of plasmid DNAs encoding these molecules would create significant potential safety hazards. As an alternative to DNA polynucleotide vectors, we explored the utility of mRNA vehicles for inducing foreign gene expression in muscle cells in vivo. Synthetic reporter-gene encoding mRNA transcripts were derived for this analysis. The Sindbis virus vector was also used to derive luciferase mRNA transcripts which possessed self-replication capacity. In these studies, it could be shown that the replicative vector was capable of directing significantly elevated levels of reporter gene expression in myocytes compared to a non-replicative mRNA species. In addition, the replicative species was capable of achieving significantly prolonged levels of in vivo gene expression compared to non-replicative mRNA. Both of these characteristics will make replicative mRNA vectors of utility for polynucleotide-based immunization protocols.

Animals↗
PubMed1995

Characterization of a messenger RNA polynucleotide vaccine vector.

We have constructed mRNA transcripts encoding luciferase and human carcinoembryonic antigen (CEA) which are capped, polyadenylated, and stabilized by human beta-globin 5' and 3' untranslated regions. The mRNA construct encoding human CEA directed CEA expression in mouse fibroblasts in vitro following liposome-mediated transfection. The luciferase encoding mRNA transcripts mediated luciferase expression in vivo following i.m. injection. Based on the demonstration of protein expression in vitro and in vivo, the feasibility of using such a vector as a tumor vaccine was examined. In this pilot study, seven mice received 50 micrograms mRNA transcripts encoding CEA twice weekly for 5 weeks by i.m. injection followed by challenge with syngeneic, CEA-expressing tumor cells. This dose and schedule "primed" an immune response to CEA. Five of seven mRNA-immunized mice demonstrated anti-CEA antibody 3 weeks after tumor challenge whereas control mice had no evidence of antibody response. This strategy might be particularly useful to induce an immune response to a proto-oncogene product or growth factor which poses a risk of inducing malignant transformation consequent to prolonged protein expression.

Animals↗
PubMed1995

Paclitaxel metabolites in human plasma and urine: identification of 6 alpha-hydroxytaxol, 7-epitaxol and taxol hydrolysis products using liquid chromatography/atmospheric-pressure chemical ionization mass spectrometry.

Reversed-phase high-performance liquid chromatography/mass spectrometry (LC/MS), with an atmospheric-pressure chemical ionization (APCI) interface, has been applied to the identification of metabolites and derivatives of paclitaxel (taxol) in plasma and urine of patients treated with this new anticancer drug. Protonated molecules with substantial fragmentation were obtained using this ionization technique. The three ion series observed are characteristic of the intact molecule, the taxane ring, and the side chain at C13. Their analysis gives information about chemical modifications of the taxane structure at different positions of the molecule. Urine and plasma extracts were evaluated using the capacity to perform MS analysis directly on the entire effluent from conventional LC columns. Excellent spectra were obtained with 50 pmol of separated compounds in full scan mode. This technique allowed highly sensitive identification of 6 alpha-hydroxytaxol, the major human biliary metabolite, and of 7-epitaxol in extracts of plasma and urine from patients. Taxol hydrolysis derivatives were observed for the first time in urine 24 hours after the end of the infusion period. Sensitivity could be increased further using single ion monitoring (SIM) mode, once a target derivative was identified. These results demonstrate that LC/MS with an APCI interface is useful for the characterization and pharmacokinetic analysis of taxoids in biological matrices.

Bile↗
PubMed1995

Optimizing the use of cyclosporine in renal transplantation.

OBJECTIVE: To review the existing data on the use of cyclosporine (CsA) in kidney transplantation, particularly with respect to therapeutic drug monitoring. DATA SOURCES: A literature search was conducted of applicable articles related to therapeutic drug monitoring of cyclosporine in renal transplantation. Previous consensus guidelines were examined. Discussions on issues related to this topic convened in Toronto, ON, on June 15-16, 1994. DATA SYNTHESIS: The literature was analyzed to examine patient factors and drug interactions affecting CsA concentrations, the effect of CsA concentrations on patient outcome, current methods of analysis, pharmacodynamic monitoring, and new immunosuppressants. CONCLUSIONS: CsA has improved the success of kidney transplantation, reducing the incidence and severity of acute rejection and improving short-term patient and graft survival. The rate of graft loss after the first year (primarily due to chronic rejection) has remained largely unchanged. Sandimmune Neoral offers promise due to its better bioavailability and limited dependence on bile flow for absorption. Long-term studies are underway to determine its effectiveness and safety. Indications for therapeutic drug monitoring for CsA are provided.

Cyclosporine↗
PubMed1995

Fluorescent and biotinylated analogues of docetaxel: synthesis and biological evaluation.

Six novel docetaxel analogues that possess a N-(7-nitrobenz-2-oxa-1,3-diazo-4-yl)amido-6-caproyl chain in position 7 or 3' (11 and 16a), a N-(7-nitrobenz-2-oxa-1,3-diazo-4-yl)amido-3-propanoyl group at 3' (16b) and a 5'-biotinyl amido-6-caproyl chain in position 7, 10 or 3', respectively, have been synthesized. These compounds exhibit activity against microtubule disassembly similar to that of docetaxel but show discrepant activities on living cells. Although addition of microtubules to 11, 16a and b enhance their fluorescence, no shift of the emission maxima was observed. The fluorescent docetaxel derivatives show a specific labeling of microtubules in living cells, demonstrating that the microtubule cytoskeleton constitutes their main subcellular localization.

Animals↗
PubMed1995

Internal calvarial bone distraction in rabbits with experimental coronal suture immobilization: effects of overdistraction.

This study was designed to assess the effects of overdistraction of an experimentally immobilized coronal suture using an internal appliance on craniofacial growth in rabbits. Fifty-three, 1.5-week-old rabbits were used. Markers were placed on either side of the calvarial sutures. Thirty-nine rabbits had bilateral coronal suture immobilization using methyl methacrylate; 14 rabbits served as normal controls. At 6 weeks of age, the 39 immobilized rabbits were randomly assigned to four groups: (1) immobilized controls (n = 14); (2) suturectomy (n = 6); (3) suturectomy with distraction (n = 9); and (4) suturectomy with overdistraction (n = 10). Lateral head radiographs were taken at 1.5, 6, 12, and 18 weeks of age. Results revealed that, by 18 weeks of age, rabbits with overdistraction exhibited significant compensatory growth abnormalities in the cranial vault, midface, and anterior cranial base compared with the other groups. Results indicate that overdistraction may contribute to craniofacial anomalies through altered growth vectors and compressive tension-stress forces at adjacent sutures and suggest that it may be important to keep "pace" with the growing coronal suture and neurocapsular matrix during distraction to reestablish normal craniofacial morphology.

Animals↗
PubMed1995

Comparative mapping of aflatoxin pathway gene clusters in Aspergillus parasiticus and Aspergillus flavus.

Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. Aflatoxins are synthesized by condensation of acetate units; their synthesis is estimated to involve at least 16 different enzymes. In this study we have shown that at least nine genes involved in the aflatoxin biosynthetic pathway are located within a 60-kb DNA fragment. Four of these genes, nor-1, aflR, ver-1, and omtA (previously named omt-1), have been cloned in A. flavus and A. parasiticus. In addition, five other genes, pksA, uvm8, aad, ord-1, and ord-2 have been recently cloned in A. parasiticus. The pksA, aad, and uvm8 genes exhibit sequence homologies to polyketide synthase, aryl-alcohol dehydrogenase, and fatty acid synthase genes, respectively. The cDNA sequences of ord-1 and ord-2 genes, which may be involved in later steps of aflatoxin biosynthesis, have been determined; the ord-1 gene product exhibits homology to cytochrome P-450-type enzymes. By characterizing the overlapping regions of the DNA inserts in different cosmid and lambda DNA clones, we have determined the order of these aflatoxin pathway genes within this 60-kb DNA region to be pksA, nor-1, uvm8, aflR, aad, ver-1, ord-1, ord-2, and omtA in A. parasiticus and nor-1, aflR, ver-1, ord-1, ord-2, and omtA in A. flavus. The order is related to the order in enzymatic steps required for aflatoxin biosynthesis. The physical distances (in kilobase pairs) and the directions of transcription of these genes have been determined for both aflatoxigenic species.

Aflatoxins↗
PubMed1995

Evaluation of the Think First head and spinal cord injury prevention program.

OBJECTIVE: Evaluation of the impact of the Think First head and spinal cord injury prevention program on knowledge, attitudes, and behavior of 11-15 year old students toward injury risks and preventive strategies. SETTING: Three junior high and three senior high schools in rural and urban areas of Washington state. METHODS: Questionnaire survey before intervention, two weeks and three months after intervention to assess knowledge, attitude, and self reported behavior change. Observations of students as they left school property to determine bicycle helmet and seat belt use. RESULTS: Little impact on attitudes and no consistent change in knowledge or self reported behaviors. Too few students rode bicycles to accurately assess helmet use; no consistent change in seat belt use. CONCLUSION: The Think First program appears to have little impact on changes in knowledge, self reported behavior, or observed behavior. Other strategies to decrease injuries in adolescents may be more successful.

Accident Prevention↗
PubMed1995

Polar organization of gamma-tubulin in acentriolar mitotic spindles of Drosophila melanogaster cells.

The spindle pole localization of gamma-tubulin was compared in wild type and acentriolar cultured Drosophila cells using polyclonal antibodies specifically raised against the carboxy terminal amino acid sequence of Drosophila gamma-tubulin-1 (-KSEDSRSVTSAGS). During interphase, gamma-tubulin was present in the centrosome of wild type cells and accumulated around this organelle in a cell cycle dependent manner. In contrast, no such structure was observed in acentriolar cells. Wild type mitoses were homogeneously composed of biconical spindles, with two centrosome-associated gamma-tubulin spots at the poles. The mitotic apparatuses observed in the acentriolar cells were heterogeneous; multipolar mitoses, bipolar mitoses with a barrel-shaped spindle and bipolar mitoses with biconical spindles were observed. In acentriolar cells, gamma-tubulin accumulation at mitotic poles was dependent on spindle microtubule integrity. Most acentriolar spindles presented a dispersed gamma-tubulin labeling at the poles. Only well polarized and biconical acentriolar spindles showed a strong gamma-tubulin polar spot. Finally, acentriolar mitotic poles were not organized around true centrosomes. In contrast to wild type cells, in acentriolar cells the Bx63 centrosome-associated antigen was absent and the gamma-tubulin containing material dispersed readily following microtubule disassembly. These observations confirm that gamma-tubulin plays an essential role in the nucleation of microtubules even in the absence of mitotic polar organelles. In addition the data suggest that the mechanisms involved in the bipolarization of wild type and acentriolar mitoses are different, and that centrioles play a role in the spatial organization of the nucleating material containing gamma-tubulin.

Amino Acid Sequence↗
PubMed1995

Practice visits: a pilot study.

OBJECTIVE: The aim of the paper is to report a pilot study of practice visits. METHOD: The study involved 35 psychiatrists as hosts and/or visitors, as well as four non-psychiatrist visitors, with the model and subsequent design changes described. RESULTS: The Quality Assurance Committee's rationale for practice visits is detailed, together with several focal concerns raised by committee members and other Fellows of the College. CONCLUSIONS: Feedback was highly positive, with visitors being generally more positive and enthusiastic than hosts. A follow-up questionnaire indicated ongoing enthusiasm for such an activity and provided evidence of participants making changes to their practices. Identified concerns and some suggested modifications to the pilot study design are noted.

Attitude of Health Personnel↗
PubMed1995

Endocarditis-related cerebral aneurysms: radiologic changes with treatment.

PURPOSE: To document the response of mycotic aneurysms to antibiotic therapy and correlate these findings with patient outcome. METHODS: Clinical findings, CT studies, and serial cerebral angiograms of patients with endocarditis related aneurysms seen over 10 years were retrospectively reviewed. RESULTS: In 14 patients infective endocarditis was diagnosed. The patients presented with subarachnoid haemorrhage (4 patients), stroke (9 patients), and seizure (1 patient). CT findings were intracerebral hematoma (5 patients), infarcts (4 patients), subarachnoid hemorrhage (4 patients), and aneurysms (2 patients). On angiography, 10 (71%) patients had single aneurysms, and 4 (29%) patients had multiple aneurysms. Eighteen aneurysms were detected, of which 6 (33%) were centrally located, and 12 (66%) were located peripherally. The most common site was the peripheral middle cerebral artery (56%). Serial angiography during antibiotic treatment demonstrated complete resolution of 6 aneurysms (33%), with 12 aneurysms remaining after 6 weeks of treatment. Of the latter, there was no change in size in 6 aneurysms (33%), a decrease in size in 3 aneurysms (17%) and an increase in size in 3 aneurysms (17%). No new aneurysms appeared. Surgery was performed on 10 patients with residual aneurysms, 11 aneurysms being excised or clipped. After 6 weeks' treatment, there was complete recovery in 7 (50%) patients, permanent neurologic deficits in 6 patients, and death from aneurysm rebleed in 1 patient. CONCLUSION: Follow-up angiography is recommended in all patients with mycotic aneurysms to assess response to antibiotic therapy, to detect new aneurysms, and to identify those aneurysms with no response or with enlargement.

Adolescent↗
PubMed1995

Teleform scannable data entry: an efficient method to update a community-based medical record? Community care coordination network Database Group.

Community-based multi-disciplinary care of chronically ill individuals frequently requires the efforts of several agencies and organizations. The Community Care Coordination Network (CCCN) is an effort to establish a community-based clinical database and electronic communication system to facilitate the exchange of pertinent patient data among primary care, community-based and hospital-based providers. In developing a primary care based electronic record, a method is needed to update records from the field or remote sites and agencies and yet maintain data quality. Scannable data entry with fixed fields, optical character recognition and verification was compared to traditional keyboard data entry to determine the relative efficiency of each method in updating the CCCN database.

Chronic Disease↗
PubMed1994

Taxol metabolism by human liver microsomes: identification of cytochrome P450 isozymes involved in its biotransformation.

The biotransformation of taxol by human liver was investigated in vitro with microsomes isolated from adult and developing human tissues. In vitro, no metabolism was detected with kidney microsomes, whereas two metabolites were generated by liver microsomes. The most prominent metabolite, termed M5, corresponded to an hydroxylation at the C6 position on the taxane ring, while the other metabolite, termed M4, corresponded to an hydroxylation at the para-position on the phenyl ring at the C3'-position of the C13 side chain. These two taxol derivatives have been shown to be the major metabolites recovered in bile from a patient infused with taxol. Several approaches have been used to identify the cytochrome P450 (CYP) isozymes involved in these reactions. No positive correlation was observed between the in vitro synthesis of these two metabolites, suggesting that two cytochrome P450 isozymes could be involved, although they could not be distinguished by their apparent affinities (Km approximately 15 microM). The formation of metabolite M4 was substantially reduced both by antibody directed against CYP3A and by the addition of CYP3A substrates such as orphenadrine, erythromycin, troleandomycin, and testosterone. Conversely, the formation of metabolite M5 remained unaffected by antibodies against CYP3A and by CYP3A substrates but was sensitive to diazepam inhibition, a preferential substrate of CYP2C. Correlation between CYP2C content or diazepam demethylation and the synthesis of metabolite M5 was highly positive. The formation of metabolite M4 developed during the early postnatal period. In contrast, the synthesis of metabolite M5 rose only after 3 months of age. These data clearly implicate CYP3A in the formation of metabolite M4 and CYP2C in the synthesis of metabolite M5. Microsomes from patients treated with barbiturates and benzodiazepines increased the formation of metabolite M4 to the level of metabolite M5, demonstrating that drug interactions could modify the human metabolism of taxol.

Age Factors↗