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Biomedical subjects

B Willis

Publications and source records attributed to B Willis.

14 recordsLinked to original sources
PubMed1996

Disease course and late sequelae of Langerhans' cell histiocytosis: 25-year experience at the University of California, San Francisco.

PURPOSE: The purpose of our investigation was to correlate the extent and degree of organ involvement at presentation of Langerhans' cell histiocytosis (LCH) with subsequent disease course, survival, and late sequelae. MATERIALS AND METHODS: The medical records of 71 patients with a pathologic diagnosis of LCH, age 0 to 21 years, who presented between January 1, 1969 and June 30, 1994, were reviewed for organ involvement at diagnosis, treatment, disease course, and late sequelae. Supplementary data were obtained by mailed questionnaire. RESULTS: The median follow-up time from diagnosis for all patients was 8.1 years. Involvement at diagnosis included nine patients with skin-only disease, 22 with monostotic disease, 12 with polyostotic disease, and 28 with multisystem presentation. Treatment was surgery only in 17 and chemotherapy and/or radiotherapy in 54 patients. Recurrences were seen in 35 patients, with the highest rate in the polyostotic group. Ten patients died: seven with the multisystem presentation, two with monostotic disease, and one with skin-only disease. Causes included progressive LCH (n = 6) and late sequelae of either treatment (n = 3) or disease (n = 1). Late sequelae were seen in 64% of 51 patients with more than 3 years of follow-up data. The most common were skeletal defects in 42%, dental problems in 30%, diabetes insipidus in 25%, growth failure in 20%, sex hormone deficiency in 16%, hypothyroidism in 14%, hearing loss in 16%, and other CNS dysfunction in 14%. The overall estimated survival rates at 5, 15, and 20 years are 88%, 88%, and 77%, with an estimated event-free survival rate of only 30% at 15 years. CONCLUSION: Despite the favorable survival, more than half of LCH patients will have further dissemination of disease or late sequelae, including even some patients with single-system disease at diagnosis. Future treatment needs to be designed to prevent disease progression and late sequelae.

Adolescent↗
PubMed1995

Pediatric spinal blastomycosis: case report.

A 5-year-old male patient presented with flank pain, limping, weight loss, and cachexia. Magnetic resonance imaging revealed destructive vertebral changes, an epidural mass, psoas abscesses, and lack of involvement of the disc spaces. Blastomyces dermatitidis was isolated from a needle aspiration specimen. Sparing of the disc spaces, an unusual finding, suggested that the spread of infection was by way of paravertebral structures and surrounding potential spaces. Management was simplified by using gadolinium contrast-enhanced magnetic resonance imaging, which indicated that the epidural mass was mainly solid, thereby obviating abscess drainage.

Amphotericin B↗
PubMed1993

Developments in three-dimensional stereo brightfield microscopy.

We present recent developments of a widefield computer/microscope system and image reconstruction algorithm for producing three-dimensional (3D) increased depth of field images in the form of brightfield stereo pairs of thick specimens. The theoretical principle of this image reconstruction technique is based on Weiner-type inverse filtering. A number of extensions and refinements to our previous work have included further testing of the system with a broader class of specimens and the implementation of several pragmatic refinements important for future 3D microscopy systems. These refinements include histogram modification routines for improving visualization, a preprocessing routine to eliminate edge artifacts due to circular convolution and other effects, stereo viewing angle optimization, a rule of thumb estimate for the axial sampling rate, and incorporation of a variation of the Fast Fourier Transform and filtering operations that significantly reduce computational time. Images of spyrogyra, neonatal rat hippocampal neurons, and cervical/vaginal cell smears are presented to show the utility of these methods for 3D visualization. The primary advantages of these methods are that they operate with an ordinary transmitted light microscope and are inexpensively implemented on a personal computer with reasonable computation time.

Algorithms↗
PubMed1993

Iterative, constrained 3-D image reconstruction of transmitted light bright-field micrographs based on maximum likelihood estimation.

We present several image reconstruction algorithms for generating three-dimensional (3-D) renderings of bright-field micrographs that are founded on maximum likelihood estimation (MLE) theory. The basic principle of the algorithms is in estimating the values of the optical densities of the specimen. A computer simulation and initial experimental testing of a steepest ascent version of the algorithm is presented. The computer simulation demonstrates that the MLE algorithm has an advantage over previously used inverse filtering techniques in that it partially restores the zeroed Fourier components in the well-known missing-cone region. We present 3-D reconstructions from real biological data to show the potential of the algorithm in practical applications.

Algorithms↗