Biomedical subjects
T Greenwell
Publications and source records attributed to T Greenwell.
Unenhanced helical CT for renal colic--is the radiation dose justifiable?
AIM: The purpose of this study was to define and compare the radiation doses to patients undergoing computed tomography (CT) or intravenous urography (IVU) for the investigation of renal colic. METHODS: The IVU dose was calculated from dose area product measurements for 27 abdominal films (AXR) and a review of 30 IVUs performed to investigate renal colic. The effective dose to a patient undergoing CT was calculated using anthropomorphic model data. Fifty patients underwent CT for the investigation of renal colic over a 6-week period. RESULTS: CT following our protocol confers an average effective dose of 4.7 mSv. An IVU to investigate renal colic used 2.5 AXRs. A 3 film IVU gives an average dose of 1.5 mSv. Forty-two CT examinations were abnormal and the findings are described in the text. CONCLUSION: Although unenhanced CT confers diagnostic advantages and avoids the risks of intravenous contrast medium, this should be considered against the increased radiation dose to the patient which in our institution is over three times that of an IVU.
A mother who wants her son circumcised.
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The clinical utility of measuring free-to-total prostate-specific antigen (PSA) ratio and PSA density in differentiating between benign prostatic hyperplasia and prostate cancer.
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The inhibitory activity of an HIV type 1 peptide correlates with its ability to interact with a leucine zipper structure.
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Propensity for a leucine zipper-like domain of human immunodeficiency virus type 1 gp41 to form oligomers correlates with a role in virus-induced fusion rather than assembly of the glycoprotein complex.
For a number of viruses, oligomerization is a critical component of envelope processing and surface expression. Previously, we reported that a synthetic peptide (DP-107) corresponding to the putative leucine zipper region (aa 553-590) of the transmembrane protein (gp41) of human immunodeficiency virus type 1 (HIV-1) exhibited alpha-helical secondary structure and self-associated as a coiled coil. In view of the tendency of this type of structure to mediate protein association, we speculated that this region of gp41 might play a role in HIV-1 envelope oligomerization. However, later it was shown that mutations which should disrupt the structural elements of this region of gp41 did not affect envelope processing, transport, or surface expression (assembly oligomerization). In this report we compare the effects of amino acid substitutions within this coiled-coil region on structure and function of both viral envelope proteins and the corresponding synthetic peptides. Our results establish a correlation between the destabilizing effects of amino acid substitutions on coiled-coil structure in the peptide model and phenotype of virus entry. These biological and physical biochemical studies do not support a role for the coiled-coil structure in mediating the assembly oligomerization of HIV-1 envelope but do imply that this region of gp41 plays a key role in the sequence of events associated with viral entry. We propose a functional role for the coiled-coil domain of HIV-1 gp41.
A synthetic peptide from HIV-1 gp41 is a potent inhibitor of virus-mediated cell-cell fusion.
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