Colonic perforation at CT colonography in a patient without known colonic disease.
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Aged↗
Biomedical subjects
David Hough
Publications and source records attributed to David Hough.
An rxr/usp homolog from the parasitic nematode, Dirofilaria immitis.
Filarial parasites are responsible for several serious human diseases with symptoms such as lymphoedema, elephantiasis, and blindness. An understanding of how these parasites pass through developmental checkpoints may suggest potential targets for intervention. A useful model system for the study of the human parasites is the closely related nematode Dirofilaria immitis, the causative agent of dog heartworm disease. In D. immitis, molting from the third to the fourth larval stage can be induced in vitro by the insect molting hormone, 20-hydroxyecdysone, suggesting that this, or some related steroid, may play a similar role in the development of D. immitis. The holoreceptor of 20-hydroxyecdysone consists of two nuclear receptors (NRs) ecdysone receptor (EcR) and ultraspiracle (USP), USP being the insect orthologue of the vertebrate RXR. We have identified a D. immitis rxr/usp, Di-rxr-1 (NR2B4). Di-RXR-1 can bind in vitro to EcR and DHR38, both known insect USP partners. Like, USP, it activates transcription in Drosophila Schneider S2 cells in a 20-hydroxyecdysone-dependent manner, via its interaction with the endogenous EcR protein. By Northern blot analysis, Di-rxr-1 mRNA is detected in adult females, but not in males. This is the first characterization of a nematode rxr/usp.
Amino Acid Sequence↗
Amplitude effects on electrocochleography outcomes.
OBJECTIVE: Electrocochleography measures in humans were examined to determine factors affecting results. STUDY DESIGN: Retrospective study. METHODS: Analysis was performed on data from 479 patients seen from 1998 to 2002 who underwent electrocochleography with a tympanic membrane electrode. Measures from click evoked electrocochleography (the summating potential to action potential ratio [SP/AP]) were compared with tone evoked electrocochleography (the SP amplitude). RESULTS: Findings indicate a strong correlation between click and tone measures if the AP from click measures was over 1 microV (P <.001), but no significant correlation between these measures if the AP was under 1 microV. Results were also analyzed with respect to patient hearing sensitivity and final diagnosis. CONCLUSION: Tympanic membrane electrocochleography is more efficacious when the AP from click stimulation is over 1 microV.
Adolescent↗
Effects of 5,6-dimethylxanthenone-4-acetic acid on human tumor microcirculation assessed by dynamic contrast-enhanced magnetic resonance imaging.
PURPOSE: 5,6-Dimethylxanthenone-4-acetic acid (DMXAA) causes vascular shutdown in preclinical models. Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) studies were performed in the phase I trials to examine changes related to blood flow and permeability in tumor and muscle. PATIENTS AND METHODS: Sixteen patients treated with DMXAA from 500 to 4,900 mg/m(2) had DCE-MRI examinations before and after treatment. The maximum gradient, the maximum enhancement, and the area under the signal-intensity-time curve (AUC) over the first 90 seconds were calculated for each pixel in regions of interest (ROIs) in muscle and tumor, and the median value for each ROI was obtained. Changes after treatment were compared with 95% limits of agreement for an individual and for groups using data from our reproducibility study. RESULTS: Nine of 16 patients had significant reductions in AUC 24 hours after the first dose of DMXAA, and eight of 11 patients had reductions of up to 66% in AUC 24 hours after the last dose. Mean reductions in gradient, enhancement, and AUC were 25%, 18%, and 31%, respectively, 24 hours after the last dose, significantly greater than the 95% limits of change for a group of 11 patients. Enhancement and AUC in muscle 24 hours after the first dose were significantly reduced, but no significant changes were seen 24 hours after the last dose. CONCLUSION: DMXAA significantly reduces DCE-MRI parameters related to tumor blood flow, over a wide dose range, consistent with the reported tumor vascular targeting activity. Further clinical evaluation of DMXAA is warranted.
Adult↗