Operational radiologic image archive on digital optical disks

A digital optical disk archive for storage of computed radiographic, computed tomographic, magnetic resonance, ultrasonographic, and digitized film radiographic images was installed. In the system, digital images enter a minicomputer, are temporarily stored on magnetic disks, and are archived onto write-once read-many optical disks at their full resolution. A pictorial index of minified images is maintained for each patient. After 8 months of operation, 49,400 megabytes of images had been retained on 19 optical disks stored, after January 1987, in a mechanical jukebox-style optical disk library. The success rate for archival capture of images during the initial period was 96.6%. The failures were due to overfilling of the magnetic disk, a problem addressed through the addition of a second magnetic disk unit. There were no medium-related image errors during the early period. Problems resulting from the slow speed of optical disk systems were addressed operationally by initiating recall of a patient's archived images from the optical to the faster magnetic disk as soon as the system received a request to acquire a new image. Also, optical disk retrieval times are expected to improve with technologic development.     

Vertebral bone density in children: effect of puberty

To determine changes in bone density during growth, trabecular vertebral density and an index of spinal cortical bone were measured with quantitative computed tomography in 101 children. The children were divided by age into three groups: prepubertal, indeterminate, and pubertal. Compared with prepubertal children, pubertal adolescents had significantly higher trabecular bone density and more compact bone in the spine (P less than .001). After controlling for puberty, vertebral bone density failed to correlate significantly with age, sex, weight, height, surface area, and body mass index. The results indicate that bone density increases markedly during puberty.     

Neuroplasticity and cellular resilience in bipolar disorder

Manji HK, Zhou R, Chen G. Neuroplasticity and cellular resilience in bipolar disorder. Bipolar Disord 2002: 4(Suppl. 1): 56–57. © Blackwell Munksgaard, 2002     

A genome-wide association scan on estrogen receptor-negative breast cancer

Introduction

Breast cancer is a heterogeneous disease and may be characterized on the basis of whether estrogen receptors (ER) are expressed in the tumour cells. ER status of breast cancer is important clinically, and is used both as a prognostic indicator and treatment predictor. In this study, we focused on identifying genetic markers associated with ER-negative breast cancer risk.

Methods

We conducted a genome-wide association analysis of 285,984 single nucleotide polymorphisms (SNPs) genotyped in 617 ER-negative breast cancer cases and 4,583 controls. We also conducted a genome-wide pathway analysis on the discovery dataset using permutation-based tests on pre-defined pathways. The extent of shared polygenic variation between ER-negative and ER-positive breast cancers was assessed by relating risk scores, derived using ER-positive breast cancer samples, to disease state in independent, ER-negative breast cancer cases.

Results

Association with ER-negative breast cancer was not validated for any of the five most strongly associated SNPs followed up in independent studies (1,011 ER-negative breast cancer cases, 7,604 controls). However, an excess of small P-values for SNPs with known regulatory functions in cancer-related pathways was found (global P = 0.052). We found no evidence to suggest that ER-negative breast cancer shares a polygenic basis to disease with ER-positive breast cancer.

Conclusions

ER-negative breast cancer is a distinct breast cancer subtype that merits independent analyses. Given the clinical importance of this phenotype and the likelihood that genetic effect sizes are small, greater sample sizes and further studies are required to understand the etiology of ER-negative breast cancers.     

The influence of flexed-knee gait on the energy cost of walking in children

There is ah understanding that walking with flexed knees contributes to the increased energy cost of walking found in children with neurological conditions. To determine the influence of flexed-knee gait on energy cost of walking in a group of children without neurological abnormality, the gait patterns of 10 normal children were studied using a Vicon system and standard marker set. A telemetric system (Cosmed K2) was then used to measure the oxygen cost of walking of the same children. The tests were repeated restricting the subjects' knee extension bilaterally, using hinged braces, set to 0, 15, 30, and 45° of flexion. Although the braces themselves caused a significant increase in O₂ cost (mL/kg/m) (P<0.05), due to a decrease in walking speed, no further significant increase in oxygen cost was demonstrated regardless of the degree of knee flexion imposed, despite a significant increase in measured hip flexion and ankle dorsiflexion at the 45° of knee flexion setting (P<0.05). We propose that moderate flexed-knee gait does not of itself cause an increase in the energy cost of walking and that other factors present in the physically disabled child are likely to be implicated.