Current usage of nonionic contrast

All physicians who had billed Pennsylvania Blue Shield for at least three intravenous contrast studies during 1989 were surveyed on their use of nonionic versus ionic contrast. This surveyed group represents a diversity of hospital sizes, practice types, and group sizes. Of the 383 physician groups surveyed, responses were obtained from 285. The majority of the responding groups were radiologists (94.0%). Nonionic contrast is utilized in 41.3% of all intravenous studies. Radiologists use nonionic contrast in a much greater proportion than nonradiologists (P < 0.0001), with 17.6% of radiologists utilizing nonionic contrast in all of their patients. Conversely, 75% of nonradiologists utilize ionic contrast in all of their patients. For all physician groups surveyed, 40.3% utilize nonionic for at least 50%, while 27.6% use nonionics for more than 75% of their patients. The routine use of steroid premedication prior to the injection of ionic contrast is not a common practice. The increased utilization of nonionic contrast found in this survey may reflect the cross-section of physicians and practice types surveyed or may represent changing practice patterns among physicians utilizing contrast material.     

Photodynamic therapy of normal rat arteries after photosensitisation using disulphonated aluminium phthalocyanine and 5-aminolaevulinic acid.

Photodynamic therapy of cancer exposes adjacent arteries to the risk of injury and the possibility of haemorrhage and thrombosis. The nature of photodynamic injury to normal arteries has not been satisfactorily defined, and the ability of arteries to recover with time is unclear. To clarify these issues, we have investigated the effects of PDT on rat femoral arteries, using a second-generation photosensitiser, disulphonated aluminium phthalocyanine, and a new method of photosensitisation, using endogenous synthesis of protoporphyrin IX following systemic administration of 5-aminolaevulinic acid (ALA). Pharmacokinetic studies of sensitiser fluorescence were carried out to determine peak levels of sensitiser. Subsequently photodynamic therapy at times corresponding to maximal fluorescence was performed using two light doses, 100 and 250 J cm-2. The nature of injury sustained and recovery over a 6 month period was investigated. Three days following PDT, all vessels treated showed complete loss of endothelium, with death of all medial smooth muscle cells, leaving an acellular flaccid artery wall. No vascular occlusion, haemorrhage or thrombosis was found. A striking feature was the lack of inflammatory response in the vessel wall at any time studied. Re-endothelialisation occurred in all vessels by 2 weeks. The phthalocyanine group showed repopulation of the media with smooth muscle cells to be almost complete by 3 months. However, the ALA group failed to redevelop a muscular wall and remained dilated at 6 months. Luminal cross-sectional area of the ALA-treated group was significantly greater than both control and phthalocyanine groups at 6 months. All vessels remained patent. This study indicates that arteries exposed to PDT are not at risk of catastrophic haemorrhage or occlusion, a finding that is of significance for both the local treatment of tumours and the use of PDT as an intraoperative adjunct to surgery for the ablation of microscopic residual malignant disease.     

Image-directed percutaneous biopsies with a biopsy gun

Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.     

Comparison of DNA- and RNA-based methods for detection of truncating BRCA1 mutations

A number of methods are used for mutational analysis of BRCA1, a large multi-exon gene. A comparison was made of five methods to detect mutations generating premature stop codons that are predicted to result in synthesis of a truncated protein in BRCA1. These included four DNA-based methods: two-dimensional gene scanning (TDGS), denaturing high performance liquid chromatography (DHPLC), enzymatic mutation detection (EMD), and single strand conformation polymorphism analysis (SSCP) and an RNA/DNA-based protein truncation test (PTT) with and without complementary 5' sequencing. DNA and RNA samples isolated from 21 coded lymphoblastoid cell line samples were tested. These specimens had previously been analyzed by direct automated DNA sequencing, considered to be the optimum method for mutation detection. The set of 21 cell lines included 14 samples with 13 unique frameshift or nonsense mutations, three samples with two unique splice site mutations, and four samples without deleterious mutations. The present study focused on the detection of protein-truncating mutations, those that have been reported most often to be disease-causing alterations that segregate with cancer in families. PTT with complementary 5' sequencing correctly identified all 15 deleterious mutations. Not surprisingly, the DNA-based techniques did not detect a deletion of exon 22. EMD and DHPLC identified all of the mutations with the exception of the exon 22 deletion. Two mutations were initially missed by TDGS, but could be detected after slight changes in the test design, and five truncating mutations were missed by SSCP. It will continue to be important to use complementary methods for mutational analysis.