Structure of poly d(AI).poly d(CT) in two different packing arrangements

X-ray diffraction analysis of poly d(AI).poly d(CT) in oriented and polycrystalline fibers has revealed the DNA structure to be a 10-fold, right-handed, antiparallel, Watson-Crick base paired double helix in two distinct packing arrangements corresponding to one and two helices, respectively, in the unit cell. The helix pitch is 32.1 A and 32.4 A in the two cases, almost 1.5 A shorter than in classical B-DNA. The resulting B'-DNA geometry, described in terms of a tetranucleotide repeat which is conformationally similar to B-DNA, has its minor groove closely shut and major groove correspondingly widened, thus striking a sharp morphological contrast to B-DNA. According to difference electron density maps, a spine of hydration along the minor groove connects both strands and provides structural stability; ordered sodium ions and water molecules are actively involved in bridging the phosphate groups of neighboring helices. The crystallographic R-values for these two allomorphs are 0.26 and 0.20, respectively, for data up to 3.0 A resolution.     

Determining the cost of a clinical intervention through the use of shadow pricing

This article reviews the scientific literature in several areas important to the delivery of palliative care: multicultural issues, education, comprehensive outcome measures and ethics. Most of the research can be classified as fundamental rather than intervention research according to the Cancer Control Framework of the National Cancer Institute of Canada. Desired outcomes of interventions are most often defined from the health care professional's perspective but need to be defined from the patient's perspective. In areas such as multicultural issues and the effect of the volunteer on the patient, there is almost no research. The complexity of studying the best way to deliver palliative care would benefit from the input of colleagues who have experience addressing these issues in other patient populations.     

Primary chemotherapy for stage 2 testis cancer

To evaluate the efficacy and toxicity of primary chemotherapy in patients with stage 2 (retroperitoneal lymph node metastases) testis cancer, 20 consecutive patients referred to Groote Schuur Hospital between September 1992 and March 1994 were reviewed. There were 10 patients with non-bulky non-seminomatous germ cell tumour (NSGCT), 5 with bulky NSGCT and 5 with bulky seminoma. The treatment regimen consisted initially of 4 cycles of cisplatin, etoposide and bleomycin. Patients with NSGCT and a residual mass after chemotherapy subsequently underwent retroperitoneal lymph node dissection (RPLND) and those with seminoma underwent a low dose of irradiation to the mass. In 7 (70%) of the 10 patients with non-bulky NSGCT, there was a complete response to chemotherapy and 3 patients underwent limited RPLND. One patient relapsed at follow-up but remains clear of disease after salvage therapy. The survival rate is 100% at a median follow-up of 60 months (range 12-143 months). In 5 patients with bulky NSGCT there was no complete response to chemotherapy. Three have undergone limited RPLND. The survival rate is 52% at a median follow-up of 130 months (range 108-152 months). In 5 patients with bulky seminomas, the survival rate is 100% at a median follow-up of 55 months (range 29-92 months). Toxicity has been modest except for 1 patient who died postoperatively in the early part of the study. Four patients have fathered children after treatment. We conclude that primary chemotherapy is the treatment of choice for patients with stage 2 testis cancer.     

Continued development of the Nimbus/University of Pittsburgh (UOP) axial flow left ventricular assist system

Nimbus and the University of Pittsburgh (UOP) have continued the development of a totally implanted axial flow blood pump under the National Institutes of Health (NIH) Innovative Ventricular Assist System (IVAS) program. This 62 cc device has an overall length of 84 mm and an outer diameter of 34.5 mm. The inner diameter of the blood pump is 12 mm. It is being designed to be a totally implanted permanent device. A key achievement during the past year was the completion of the Model 2 pump design. Ten of these pumps have been fabricated and are being used to conduct in vitro and in vivo experiments to evaluate the performance of different materials and hydraulic components. Efforts for optimizing the closed loop speed control have continued using mathematical modeling, computer simulations, and in vitro and in vivo testing. New hydraulic blade designs have been tested using computational fluid dynamics (CFD) and flow visualization. A second generation motor was designed with improved efficiency. To support the new motor, a new motor controller fabricated as a surface mount PC board has been completed. The program is now operating under a formal QA system.     

Magnetic resonance imaging scanning in the diagnosis of zone II flexor tendon rupture

This study was undertaken to determine the usefulness of magnetic resonance imaging (MRI) in the diagnosis of flexor tendon rupture in patients who had prior surgery. Magnetic resonance imaging scans were performed on 11 digits (16 tendons) with the clinical diagnosis of flexor tendon rupture. Clinical suspicion correlated with MRI and surgical findings. Clinical examination yielded a 60% accuracy in diagnosis. MRI differentiated rupture from adhesions with a 100% accuracy rate. The MRI scan is a valuable tool in diagnosing tendon ruptures and may help reduce the incidence of unnecessary tendon explorations.     

International surveillance of bloodstream infections due to Candida species: frequency of occurrence and antifungal susceptibilities of isolates collected in 1997 in the United States, Canada, and South America for the SENTRY Program. The SENTRY Participant Group

An international program of surveillance of bloodstream infections (BSIs) in the United States, Canada, and South America between January and December 1997 detected 306 episodes of candidemia in 34 medical centers (22 in the United States, 6 in Canada, and 6 in South America). Eighty percent of the BSIs were nosocomial and 50% occurred in patients hospitalized in an intensive care unit. Overall, 53.3% of the BSIs were due to Candida albicans, 15.7% were due to C. parapsilosis, 15.0% were due to C. glabrata, 7.8% were due to C. tropicalis, 2.0% were due to C. krusei, 0.7% were due to C. guilliermondii, and 5.8% were due to Candida spp. However, the distribution of species varied markedly by country. In the United States, 43.8% of BSIs were due to non-C. albicans species. C. glabrata was the most common non-C. albicans species in the United States. The proportion of non-C. albicans BSIs was slightly higher in Canada (47.5%), where C. parapsilosis, not C. glabrata, was the most common non-C. albicans species. C. albicans accounted for 40.5% of all BSIs in South America, followed by C. parapsilosis (38.1%) and C. tropicalis (11.9%). Only one BSI due to C. glabrata was observed in South American hospitals. Among the different species of Candida, resistance to fluconazole (MIC, > or = 64 microg/ml) and itraconazole (MIC, > or = 1.0 microg/ml) was observed with C. glabrata and C. krusei and was observed more rarely among other species. Isolates of C. albicans, C. parapsilosis, C. tropicalis, and C. guilliermondii were all highly susceptible to both fluconazole (99.4 to 100% susceptibility) and itraconazole (95.8 to 100% susceptibility). In contrast, 8.7% of C. glabrata isolates (MIC at which 90% of isolates are inhibited [MIC90], 32 microg/ml) and 100% of C. krusei isolates were resistant to fluconazole, and 36.9% of C. glabrata isolates (MIC90, 2.0 microg/ml) and 66.6% of C. krusei isolates were resistant to itraconazole. Within each species there were no geographic differences in susceptibility to fluconazole or itraconazole.     

Sequential transfer of free flap to two defects

This case report describes the use of a single lateral arm flap sequentially transferred to two defects in a bilateral hand injury. We believe this is a novel approach in reconstructing defects in bilateral hands when a staged reconstruction is planned.