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Trevor Williams

Publications and source records attributed to Trevor Williams.

43 records · Page 3Linked to original sources
PubMed2003

Effect of tinopal LPW on the insecticidal properties and genetic stability of the nucleopolyhedrovirus of Spodoptera exigua (Lepidoptera: Noctuidae).

The influence of an optical brightener, Tinopal LPW, on the activity of a purified genotype of the nucleopolyhedrovirus (SeMNPV) of the beet armyworm, Spodoptera exigua (Hübner), was determined in second to fifth instar (L2-L5) S. exigua. When mixed with viral occlusion bodies (OB) 1% Tinopal LPW significantly reduced the median lethal dose (LD50) of the virus in all instars compared with insects treated with SeMNPV alone. Levels of enhancement, as determined by LD50 values, ranged from 2.6- to 580-fold, depending on the instar. The greatest enhancement occurred on the two later instars, L4 (70-fold) and L5 (580-fold), which show a much higher resistance to SeMNPV infection than earlier instars. The median time to death (MTD) values were not significantly different in any instar among larvae treated with SeMNPV + Tinopal LPW and those treated with SeMNPV alone. Larval development in SeMNPV + Tinopal LPW treated larvae was retarded, in second and fourth instars, compared with controls or larvae treated with SeMNPV alone. The OB yields from SeMNPV treated larvae were almost 1.6-fold greater in second instars (9.3 x 10(6) OBs/larvae), and 1.9-fold greater in fourth instars (1.9 x 10(8) OBs/larvae), than those obtained in larvae treated with SeMNPV + Tinopal LPW. The addition of 1% Tinopal LPW to the virus suspension did not alter the genotypic composition of viral progeny during four successive passages of the virus.

Animals↗
PubMed2002

Addition of inhaled corticosteroids to systemic immunosuppression after lung transplantation: a double-blind, placebo-controlled trial.

BACKGROUND: It is postulated that bronchiolitis obliterans syndrome (BOS) is preceded by airway inflammation that has been described even in stable lung transplant recipients. Airway inflammation is known to be suppressed by inhaled steroids in other chronic inflammatory lung diseases, e.g., asthma and chronic obstructive pulmonary disease. BOS is the major cause of morbidity and mortality after lung transplantation. OBJECTIVE: To examine the effect of inhaled corticosteroids on the development of BOS in lung transplant recipients. METHODS: Thirty patients were recruited and randomized in a double-blind fashion to receive either 750 microg of fluticasone propionate (FP) or an identical-appearing placebo twice daily for 3 months; 20 of this group continued until 2 years posttransplantation. Detailed spirometry was performed regularly throughout the study. RESULTS: In the short-term study no differences were found in any examined parameters. In the long-term component of the study no differences were found in the development of neither BOS nor survival. There were minor differences in bronchoalveolar lavage (BAL) lymphocyte percentages. CONCLUSIONS: FP is ineffective for the prevention of BOS after lung transplantation despite the airway inflammation that characterizes this condition. Inadequate local delivery, timing of the therapy relative to transplantation and inherent steroid resistance of this condition may explain the negative finding of this study.

Administration, Inhalation↗
PubMed2002

Scoring system for estimating age in the foot skeleton.

This study assesses chronological age of immature individuals from the degree of ossification evident in the foot skeleton. We considered all tarsal and ray bones in various combinations to determine the most sensitive indicators of chronological age. Skeletal maturity was rated according to a subjective but simple scoring system applied to radiographs of normal feet of children of known chronological age. Scales for assessing the primary center of ossification, secondary center of ossification, and state of fusion are defined. In general, as expected, females show earlier onset of skeletal maturity than males; in particular, females in our sample are skeletally mature in most elements beginning 48 months prior to the earliest incidence of skeletal maturity in males for the same bones. Females in our sample show a marked tendency toward skeletal maturity of all elements by 150 months of age, while males do not show the same tendency until approximately 200 months of age. In general within each sex, consecutive states of fusion show broad overlap in range of chronological age within each bone. Combining scores from several different bones enables a reasonable estimate of potential age in a test application of the model.

Adolescent↗
PubMed2002

Parasitoid-mediated transmission of an iridescent virus.

We examined the interaction between an invertebrate iridescent virus (IIV) isolated from Spodoptera frugiperda (J.E. Smith) and the solitary ichneumonid endoparasitoid Eiphosoma vitticolle Cresson. In choice tests, parasitoids examined and stung significantly more virus infected than healthy larvae, apparently due to a lack of defense reaction in virus infected hosts. Parasitoid-mediated virus transmission was observed in 100% of the female parasitoids that stung a virus infected host in the laboratory. Each female parasitoid transmitted the virus to an average (+/-SE) of 3.7+/-0.3 larvae immediately after stinging an infected larva. Caged field experiments supported this result; virus transmission to healthy larvae only occurred in cages containing infected hosts (as inoculum) and parasitoids (as vectors). The virus was highly detrimental to parasitoid development because of premature host death and lethal infection of the developing endoparasitoid. Female parasitoids that emerged from virus infected hosts did not transmit the virus to healthy hosts. We suggest that the polyphagous habits of many noctuid parasitoids combined with the catholic host range of most IIVs may represent a mechanism for the transmission of IIVs between different host species in the field.

Animals↗
PubMed2002

Requirement for AP-2alpha in cardiac outflow tract morphogenesis.

Most developing structures that express the transcription factor gene AP-2alpha are compromised in AP-2alpha mutant mouse embryos. Since the cardiac neural crest population is one prominent site of AP-2alpha expression, and because the neural crest is known to be required for normal cardiac morphogenesis, we have investigated the involvement of AP-2alpha in cardiac development. All AP-2alpha-deficient embryos examined had malformations of the outflow tract of the developing heart: most had double outlet right ventricle, and a small fraction had persistent truncus arteriosus. To visualize AP-2alpha-expressing cells during the period of cardiac morphogenesis, we established a new mutant germline allele in which an IRES-lacZ sequence was inserted by homologous recombination into the AP-2alpha locus. Positive expression was observed in the cardiac neural crest population during the E9.5-10.5 period (as well as in other known domains of AP-2alpha expression previously noted by in situ hybridization studies), and was mostly extinguished by E11.5 when the cardiac neural crest has migrated into the outflow tract of the developing heart. Importantly, the distribution of AP-2alpha-expressing cardiac neural crest appeared to be identical in normal and mutant embryos. From this analysis, we propose that the AP-2alpha gene functions within the neural crest lineage, that AP-2alpha is not required for neural crest cell migration, and that normal AP-2alpha gene function is required prior to E11.5. AP-2alpha may be involved in an interaction between neural crest and surrounding tissues in the subpharyngeal region, thereby promoting normal outflow tract morphogenesis.

Animals↗
PubMed2002

Transcription factor AP-2gamma is essential in the extra-embryonic lineages for early postimplantation development.

The members of the AP-2 family of transcription factors play important roles during mammalian development and morphogenesis. AP-2gamma (Tcfap2c - Mouse Genome Informatics) is a retinoic acid-responsive gene implicated in placental development and the progression of human breast cancer. We show that AP-2gamma is present in all cells of preimplantation embryos and becomes restricted to the extra-embryonic lineages at the time of implantation. To study further the biological function of AP-2gamma, we have generated Tcfap2c-deficient mice by gene disruption. The majority of Tcfap2c(-/-) mice failed to survive beyond 8.5 days post coitum (d.p.c.). At 7.5 d.p.c., Tcfap2c(-/-) mutants were typically arrested or retarded in their embryonic development in comparison to controls. Morphological and molecular analyses of mutants revealed that gastrulation could be initiated and that anterior-posterior patterning of the epiblast remained intact. However, the Tcfap2c mutants failed to establish a normal maternal-embryonic interface, and the extra-embryonic tissues were malformed. Moreover, the trophoblast-specific expression of eomesodermin and Cdx2, two genes implicated in FGF-responsive trophoblast stem cell maintenance, was significantly reduced. Chimera studies demonstrated that AP-2gamma plays no major autonomous role in the development of the embryo proper. By contrast, the presence of AP-2gamma in the extra-embryonic membranes is required for normal development of this compartment and also for survival of the mouse embryo.

Animals↗