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Biomedical subjects

D Crooks

Publications and source records attributed to D Crooks.

18 recordsLinked to original sources
PubMed2001

Aneurysmal bone cyst of the sphenoid sinus.

Aneurysmal bone cysts of the sphenoid sinus are very rare, with only six cases described in the literature. We present a case of an aneurysmal bone cyst of the sphenoid sinus with associated fibrous dysplasia in which the radiological findings had some features of a mucocoele. We discuss the differences in pathogenesis, clinical presentation and radiological appearances between these two lesions, and propose a simple drainage procedure as an effective modality of treatment.

Adult↗
PubMed2001

Malignant eccrine poroma with spinal and cerebrospinal fluid metastases: case report.

OBJECTIVE AND IMPORTANCE: A rare case of metastasizing malignant eccrine poroma (porocarcinoma) is described. This case is unique because metastasis resulted in hydrocephalus in the cerebrospinal fluid and spinal cord compression in the lumbar spine. CLINICAL PRESENTATION: A 57-year-old man presented with acute confusion, lower limb weakness, and urinary concerns. Investigation revealed acute hydrocephalus and extradural cord compression of the lumbar spine. INTERVENTION: The acute hydrocephalous was treated with a ventriculoperitoneal shunt. The spinal cord and conus were decompressed by laminectomy and supplemented with pedicular screw fixation. CONCLUSION: The case reported here is the first with metastases from a malignant eccrine poroma causing spinal cord compression and acute hydrocephalus. Our observation is compared with a review of the literature.

Acrospiroma↗
PubMed2001

Self-directed learning: faculty and student perceptions.

This article reports the results of a qualitative study that explored faculty and student perceptions of self-directed learning (SDL) and investigated factors that facilitate or impede it. This study was conducted at McMaster University with faculty and students in a 4-year undergraduate nursing program. Data were collected from 47 faculty and 17 students by means of focus groups that were audiotaped and transcribed. Content analysis was conducted to identify common themes in faculty and student transcripts. The themes that emerged provide insight into the educational strategy of self-directed learning and can be summarized by the following major points: (1) commitment to SDL requires students and faculty to understand the value of empowering learners to take increased responsibility for decisions related to learning; (2) students engaged in self-directed learning undergo a transformation that begins with negative feelings (i.e., confusion, frustration, and dissatisfaction) and ends with confidence and skills for lifelong learning; and (3) faculty development is important to ensure high levels of competency in facilitating self-directed learning.

Attitude↗
PubMed2000

Combined proton MR spectroscopy and dynamic contrast enhanced MR imaging of human intracranial tumours in vivo.

A study was undertaken to determine if the vascular characteristics measured by dynamic contrast-enhanced magnetic resonance imaging (primarily permeability surface area product and extracellular-extravascular tissue volume fraction) would be beneficial in explaining the inter-lesion metabolic heterogeneity displayed by human intracranial tumours. Magnetic resonance spectroscopy was carried out using a single-voxel STEAM sequence and dynamic imaging was carried out using a combination of pre-contrast proton density-weighted FSPGR images (to remove the influence of native tissue T1), bolus injection of Gd-DTPA and subsequent T1-weighted FSPGR dynamic imaging. A two-compartment pharmacokinetic model was employed to determine vascular characteristics. Results obtained from 12 meningiomas suggest a possible correlation between the level of lipids/macromolecules and permeability surface area product, although the confounding issue of extra-voxel contamination arising from lipids in the scalp and skull marrow cannot be ruled out in the more superficial lesions. Results obtained from 11 gliomas (four low and seven high grade) demonstrate that permeability surface area product is not specific for the range of vascular characteristics and metabolite profiles observed in gliomas and is therefore unable to explain metabolic heterogeneity in these lesions.

Brain Neoplasms↗
PubMed2000

E3-13.7 integral membrane proteins encoded by human adenoviruses alter epidermal growth factor receptor trafficking by interacting directly with receptors in early endosomes.

Animal cell viruses provide valuable model systems for studying many normal cellular processes, including membrane protein sorting. The focus of this study is an integral membrane protein encoded by the E3 transcription region of human adenoviruses called E3-13.7, which diverts recycling EGF receptors to lysosomes without increasing the rate of receptor internalization or intrinsic receptor tyrosine kinase activity. Although E3-13.7 can be found on the plasma membrane when it is overexpressed, its effect on EGF receptor trafficking suggests that the plasma membrane is not its primary site of action. Using cell fractionation and immunocytochemical experimental approaches, we now report that the viral protein is located predominantly in early endosomes and limiting membranes of endosome-to-lysosome transport intermediates called multivesicular endosomes. We also demonstrate that E3-13.7 physically associates with EGF receptors undergoing E3-13.7-mediated down-regulation in early endosomes. Receptor-viral protein complexes then dissociate, and EGF receptors proceed to lysosomes, where they are degraded, while E3-13.7 is retained in endosomes. We conclude that E3-13.7 is a resident early endocytic protein independent of EGF receptor expression, because it has identical intracellular localization in mouse cells lacking endogenous receptors and cells expressing a human cytomegalovirus-driven receptor cDNA. Finally, we demonstrate that EGF receptor residues 675-697 are required for E3-13.7-mediated down-regulation. Interestingly, this sequence includes a known EGF receptor leucine-based lysosomal sorting signal used during ligand-induced trafficking, which is also conserved in the viral protein. E3-13.7, therefore, provides a novel model system for determining the molecular basis of selective membrane protein transport in the endocytic pathway. Our studies also suggest new paradigms for understanding EGF receptor sorting in endosomes and adenovirus pathogenesis.

3T3 Cells↗
PubMed1999

Student and faculty learning styles in a Canadian and a Chilean self-directed, problem-based nursing program.

A descriptive comparative study was conducted to identify and compare/contrast the learning styles of nursing faculty and entry-level students in 2 self-directed (SDL), problem-based (PBL) nursing programs. The Kolb LSI-1985 was administered to 94 first-year generic students, 63 post-R.N. students, and 22 faculty members in a Canadian university nursing program. A Spanish translation was completed by 37 incoming nursing students and 13 faculty members in a Chilean university. One-way ANOVA analysis of group mean scores showed significant differences among the 4 student groups in the active experimentation learning mode. Post hoc tests confirmed that Chilean students are less likely to be active learners than their teachers or Canadian students, a finding of significance in preparing students to assume self-direction of their learning. Canadian faculty had higher abstract conceptualization scores than Chilean faculty, which has implications for faculty development of educator roles for SDL/PBL.

Adult↗
PubMed1994

Prediction of disease-free survival after therapy in Wilms' tumor using nuclear morphometric techniques.

The outlook for children with Wilms' tumor has markedly improved with the use of multimodal therapy, and survival currently exceed 85%. Current trends have been to use less intense therapy for children whose tumors have favorable histology (FH). By decreasing the amount of therapy given to patients whose conditions have an excellent chance of responding, the need for accurate criteria to separate high-risk and low-risk groups becomes imperative. Nuclear morphometric techniques have been developed and extensively tested in the author's laboratory. Preliminary studies of FH Wilms' tumors demonstrated the applicability of this technique. Herein, the authors present a retrospective study of 108 patients with FH tumors, with a mean follow-up period of 1,994 +/- 107 days (66 months) for those whose tumors did respond to therapy, and 686 +/- 61 days (23 months) for those whose tumors did not respond. The univariate predictors were age (P = .02), the skewness of nuclear roundness factor (SNRF) (P = .009), and the mean of the lower five values for nuclear ellipticity, measured by the feret diameter method (L5EFD) (P = .01). A multivariate analysis combining all three variables better separated the two groups (P = .00016). A probability function curve was constructed to predict poor prognosis. Kaplan-Meier actuarial survival analysis was used to predict disease-free survival as clinical progression, and separated the two groups (P = .0004, Wilcoxon-Gehan statistic). These results suggest that nuclear morphometry is useful in the initial assessment of patients with Wilms' tumor.

Adolescent↗
PubMed1993

The use of nuclear morphometry to predict prognosis in pediatric urologic malignancies: a review.

Wilms tumor, the most common pediatric urologic malignancy, and genitourinary rhabdomyosarcoma, the most common soft tissue sarcoma of childhood, represent two of the most commonly diagnosed pediatric urologic malignancies. The introduction and use of multimodal therapy (surgery, radiation, and chemotherapy) by the National Wilms Tumor Study (NWTS) and the Intergroup Rhabdomyosarcoma Study (IRS) groups have greatly improved the survival among children with these malignancies. Present survival rates for Wilms tumor exceed 85% and for rhabdomyosarcoma survival rates are approaching 80% as well. For Wilms tumor, current treatment trends suggest less intense therapy for those children with favorable histology tumors who are considered at relatively low risk for tumor recurrence. Likewise, the significant morbidity associated with the present therapy regimens for rhabdomyosarcomas has prompted investigators to search for individualized management schemes for children with a high probability of responding. The need for accurate criteria to separate these high and low risk groups becomes imperative. In this review we present our work using nuclear morphometry, as a prognostic indicator, to retrospectively predict response to therapy for children with Wilms tumors and genitourinary rhabdomyosarcomas.

Adolescent↗
PubMed1991

Psychosocial adjustment in women with breast cancer.

There is a plethora of studies investigating psychosocial adjustment in women with breast cancer, its correlates, clinical course, and prognosis. These studies have been conducted with varying degrees of methodologic rigor. An assessment has been made of the quality of this existing evidence to identify from the best evidence the factors which predict the adjustment status of women with breast cancer. Studies have been reviewed, using methodologic standards for the critical appraisal of studies on prognosis, developed by Sackett and colleagues in the Department of Clinical Epidemiology and Biostatistics at McMaster University (Hamilton, Ontario, Canada). Few of the studies investigating psychosocial adjustment of women with breast cancer meet all of the criteria for reviewing studies of clinical course and prognosis. This review focuses the direction and methodologic rigor required in future investigations. In particular, studies are needed that employ prospective designs and that deliberately measure or control for the extraneous prognostic variables that may affect adjustment. Future investigations need to incorporate adequate precision in measurement so that measures of the psychosocial variables are objective, reliable, and valid.

Adaptation, Psychological↗
PubMedDate not supplied

B cell non-Hodgkin cerebral lymphoma associated with an anaplastic oligodendroglioma.

Primary central nervous system lymphomas and anaplastic oligodendrogliomas are not uncommon; however, no association between the 2 has been documented to date. We describe a unique case, whereby a patient presenting with seizures and slight impairment of higher functions, underwent frontal lobectomy for a mass lesion. The histology revealed dual pathology of anaplastic oligodendroglioma and B cell non-Hodgkin lymphoma. Postoperatively, the patient received whole brain radiotherapy. The patient remained well after 18 months of follow-up with no radiological progression of a known tumor residuum.

Brain Neoplasms↗