Application of autoregressive spectral analysis to cepstral estimation of mean scatterer spacing

The problem of estimation of mean scatterer spacing in an object containing regularly spaced structures is addressed. An autoregressive (AR) spectral estimation method is compared with a conventional fast Fourier transform (FFT)-based approach for this task. Regularly spaced structures produce a periodicity in the power spectrum of ultrasonic backscatter. This periodicity is manifested as a peak in the cepstrum. A phantom was constructed for comparison of the two methods. It contained regularly spaced nylon filaments. It also contained randomly positioned glass spheres that produced incoherent backscatter. In an experiment in which this target was interrogated using broadband ultrasound, the AR spectral estimate offered considerable improvement over the FFT when the analysis gate length was on the order of the structural dimension. Advantages included improved resolution, reduction in bias and variance of scatterer spacing estimates, and greater resistance to ringing artifacts. Data were also acquired from human liver in vivo. AR spectral estimates on human data exhibited a decreased dependence on gate length. These results offer promise for enhanced spatial resolution and accuracy in ultrasonic tissue characterization and nondestructive evaluation of materials.     

AHIMA (American Health Information Management Association) executives expand their role in electronic record issues. Interview by Carolyn Dunbar

Four of the top leaders in the American Health Information Management Association met with Computers in Healthcare, detailing their coalition-building efforts to make the computer-based patient record a reality. They reinforce their belief in the eventual reality of the CPR and its security, and call for sanctions and penalties for those who misappropriate or misuse patient records.     

Immunohistochemical diagnosis of typhus rickettsioses using an anti-lipopolysaccharide monoclonal antibody

A monoclonal antibody directed against an epitope on the lipopolysaccharide of typhus-group rickettsiae was developed for the purpose of detecting this heat-stable, proteinase-resistant antigen in formalin-fixed, paraffin-embedded tissues. Rickettsia prowazekii organisms were identified in endothelium and macrophages in sections of the brains of three Egyptian men who died of epidemic louse-borne typhus in Cairo during World War II and in the brain from a recent case of typhus fever acquired in Burundi. R. typhi organisms were identified in endothelial cells from a fatal case of murine typhus and in experimentally infected mice. This approach is applicable not only to the study of archival tissues and experimental animal models but also could be used to establish a timely diagnosis of typhus-group rickettsiosis by immunohistochemical examination of cutaneous biopsies of rash lesions during the acute stage of illness.     

On white coats and professional development: the formal and the hidden curricula

White coat ceremonies are a recent phenomenon in medical education. Selected as a symbol by the Arnold P. Gold Foundation to impress upon medical students the importance of compassion and humility, the white coat has had a long association with all things medical, scientific, and healing. It is also associated with the attributes of purity and goodness traditionally symbolized by the color white. Thus, its selection as the material focus of the white coat ceremony seems natural. This article situates the white coat ceremony as a curricular event and suggests that, in addition to having the meanings cited above, the white coat has other meanings that fall into the realm of the hidden curriculum--it can symbolize caregiving hierarchies and spheres of practice, the social and economic privilege of physicians, and medicine's well-established practices of determining membership in the profession. Finally, this paper suggests several other ceremonies or rituals that may be better than the white coat ceremony for encouraging compassion and humility in medical students.     

Vesicocolonic fistulas in diverticulitis

Diverticulitis is a disease affecting patients in the fifth to sixth decades. The charts of 12 patients with cesicocolonic fistulas secondary to diverticulitis were reviewed. Their presentation was primarily urological with pneumaturia present in 10 of 12 patients and fecaluria present in 5 of 12. The process of fistulization occurs in stages. If the incipient stage can be identified early fistulization can be prevented and the morbidity and mortality rates will be reduced significantly. In older patients with bladder irritation (with or without positive urine cultures) a high degree of suspicion for diverticular disease will ensure an accurate diagnosis earlier. Patients with penumaturia or fecaluria present less of a diagnostic challenge. Cystoscopy is a reliable procedure and we recommend its use in discovering a vesicocolonic fistula. Surgical therapy should be individualized for each patient and good results were obtained with primary resection as well as staged repair.     

Design and synthesis of conformationally constrained cyclophilin inhibitors showing a cyclosporin-A phenotype in C. elegans

Cyclophilin A (CypA) is a member of the immunophilin family of proteins and receptor for the immunosuppressant drug cyclosporin A (CsA). Here we describe the design and synthesis of a new class of small-molecule inhibitors for CypA that are based upon a dimedone template. Electrospray mass spectrometry is utilised as an initial screen to quantify the protein affinity of the ligands. Active inhibitors and fluorescently labelled derivatives are then used as chemical probes for investigating the biological role of cyclophilins in the nematode Caenorhabditis elegans.