How useful is contrast enhancement after a normal unenhanced computed tomography brain scan?

An audit was performed of contrast use in 400 CT brain scans performed with and without contrast enhancement; all 400 scans were re-read by a second reader who did not know the result of the original reading. From this initial series 184 scans were identified in which the unenhanced series had been read as normal by both observers. Of these 184 studies, only one enhanced scan showed an abnormality, and this lesion is thought to be benign. In conjunction with published literature it is concluded that it is reasonable not to give contrast if there is a low expectation of a lesion being present, and if the unenhanced scan is normal. Protocols are presented for the use of intravenous contrast in CT brain scans.

A review of computerized tomography in blunt abdominal trauma at Christchurch Hospital

A review was undertaken of computerized tomography (CT) of the abdomen, performed between March 1993 and December 1994 for blunt abdominal trauma at Christchurch Hospital. CT findings were correlated with the clinical outcome. The outcome was either recovery from an abdominal point of view with or without laparotomy, or postmortem. A total of 116 CTs were reviewed, of which 76 were abnormal. CT was highly sensitive and specific for a variety of abdominal traumatic lesions. There were 1 false positive and 4 false negatives (only 2 of these significant). There was 1 non-therapeutic laparotomy based on CT findings. There was only 1 case of delayed treatment based on CT results. Three patients had unexplained findings of pneumoperitoneum. Care should be taken when interpreting the presence of free intraperitoneal air on CT scan. The possibility of missed bowel perforation should be considered, especially in the presence of free intra-abdominal fluid and no solid organ injury to account for it. CT scans are useful in the conservative management of solid organ injuries.

Mutagenesis studies of interleukin-8. Identification of a second epitope involved in receptor binding

Interleukin-8 (IL-8) is a dimeric, C-X-C chemokine, produced by a variety of cells and which elicits proinflammatory responses from the neutrophil. As a prelude to drug design, we have investigated the interactions between IL-8 and its receptor by preparing a number of single-site mutants of IL-8 and determining their activity in receptor-binding and functional assays. In order to define the binding surface as precisely as possible, we have used chemical shifts obtained from nuclear magnetic resonance spectroscopy to screen mutant proteins for structural changes which affect regions of the IL-8 surface remote from the site of mutation. In addition to a previously recognized sequence, Glu4-Leu5-Arg6 in the N-terminal peptide, we have identified a second epitope comprising a contiguous group of non-sequential, solvent-exposed, hydrophobic residues, Phe17, Phe2l, Ile22, and Leu43. These two receptor-binding regions are separated by over 20 A in the IL-8 structure and are important both for receptor binding and function. In addition, we have shown through the production of a covalently linked IL-8 dimer, that subunit dissociation is not necessary for biological activity.

Exposure factors and screen-film combinations in temporomandibular joint radiography

Exposure factors and screen-film combinations providing optimal quality are identified for transcranial and transpharyngeal temporomandibular joint views, using conventional intra-oral radiographic equipment without grids. Standardized transcranial and transpharyngeal views, using a fixed whole cadaver head, were performed. Ten readily available screen-film combinations, ranging in nominal speed 20-600, were exposed over 40-100 kV. Films were blindly and independently order ranked by three observers on the basis of sharpness and contrast of cortical outline, trabecular detail, and visualization of adjacent bony structures. Preferred screen-film combinations as a function of kV, preferred kV levels for each screen-film combination, and overall ranking irrespective of kV or screen-film combination, were established. Accepting the use of the lowest radiation dose possible for diagnostically useful radiographs but imposing arbitrarily an upper limit of 20 mGy, it was found that exposures between 50 kV and 70 kV gave the optimal result for both techniques. The amount of scattered radiation in the emergent beam differs greatly between the two techniques. The most favoured combinations for the transpharyngeal technique used screens of fine resolution. Min-r/ortho M screen and film with nominal speed 40 at 60 kV gave 8.0 mGy skin dosage at 0.8 seconds exposure; the same combination at 50 kV was the most favoured, but with skin dosage calculated at 16.7 mGy for 3.0 seconds exposure. For the transcranial technique, medium speed screens providing better differentiation of scattered radiation beams and increased speeds were preferred. Most favoured for image quality was the Lanex Fine/T-Mat G combination at 60 kV giving 17.5 mGy skin radiation dose at 1.75 seconds exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunophenotype of lymphoid cells in positive patch tests of allergic contact dermatitis

The immune phenotype of the infiltrating cells in 13 positive patch tests from 8 cases of contact dermatitis and 1 case of poison ivy was studied. An indirect immunoperoxidase technique was used in conjunction with monoclonal antibodies directed against mature T cells (Leu-1, T11), helper T cells (Leu-3A), suppressor/cytotoxic T cells (Leu-2A), killer and natural killer cells (HNK 1), B cells (B1), Langerhans cells (HLA-DR), and the common acute lymphoblastic leukemia antigen (CALLA), (J5). The majority of infiltrating mononuclear cells were Leu-1+, T11+, Leu-3A+, Leu-2A-, HLA-DR+, T9-, T10-, HNK-, B1-, J5-. Occasional T6+ cells were observed in the epidermis (including spongiotic microvesicles) and also isolated in the dermis and within the dermal mononuclear infiltrates. The phenotype was compared with cutaneous T-cell lymphoma, a disease in which contact allergy and antigenic persistence may play a role.