Biomedical subjects

Alan Jackson

Publications and source records attributed to Alan Jackson.

40 records · Page 3Linked to original sources

PubMed2002

Development and validation of a lectin-based assay for the quantitation of rat respiratory mucin.

The significance of a mucus hypersecretory phenotype to the pathogenesis of airways disease is controversial, but increasing evidence suggests that it can negatively impact upon patient health status. A critical aspect of developing our understanding of the role of mucus hypersecretion in disease is the development and appropriate use of methods permitting detection and quantitation of mucins in biological samples. However, the unique biophysical and biochemical properties of this class of glycoproteins do not lend themselves to routine quantitation. Individual pure mucins are not commercially available, the reactivity profile of commonly used reagents is generally not well characterized and assay development and validation is rarely covered adequately in the literature. Therefore quantitation of mucin in biological samples relies upon careful histochemical and biochemical characterization and partially purified mucin preparations. The absence of tools considered essential for assay development in other areas means that this characterization process does not generally lead to proof of selective detection of mucin, but rather to a level of confidence that mucin is detected and defined contaminants are not. This chapter provides an example of the process of development and validation of a lectin-based assay for quantitation of mucin in untreated complex biological samples.

Animals↗

PubMedDate not supplied

Intracanalicular optic nerve meningioma: a serious diagnostic pitfall.

We describe six cases of cannalicular optic nerve meningioma in which the diagnosis was missed for more than 1 year after the onset of symptoms. Clinical features led to a misdiagnosis of optic neuritis in all cases. Although atypical clinical progression led to further imaging studies, they did not provide the diagnosis because of inappropriate imaging protocols. Diagnosis was eventually made on the basis of high-spatial-resolution contrast-enhanced MR findings. Radiologists should have a high suspicion for the diagnosis of optic canal meningioma in patients with unexplained visual loss, particularly when visual loss is progressive. Investigation in these cases should include high-spatial-resolution MR imaging of the orbit before and after contrast medium administration, and fat suppression should be used in combination with contrast enhancement whenever possible.

Adult↗

PubMedDate not supplied

Dilatation of the Virchow-Robin space is a sensitive indicator of cerebral microvascular disease: study in elderly patients with dementia.

BACKGROUND AND PURPOSE: Virchow-Robin spaces (VRSs) are CSF spaces that accompany blood vessels as they perforate the brain substance. Dilatation of VRS is associated with microangiopathy. Microvascular disease has a major etiologic and pathogenetic role in dementias. To our knowledge, no investigators have looked at the relationship between dilated VRS on MR imaging and cerebral microvascular disease. The aim of our study was to test the hypothesis that dilatation of VRS is associated with subcortical vascular dementia. METHODS: We recruited 75 patients with Alzheimer's disease (n = 35), ischemic vascular dementia (n = 24), or frontotemporal dementia (n = 16) and 35 healthy volunteers. We assessed deep white matter and periventricular hyperintensities and the severity of VRS dilatation, as scored on MR images. Statistical group comparisons and multiple regression analyses were performed to quantify the relationship between imaging features and diagnoses. RESULTS: White matter lesions were more common in patients with ischemic vascular dementia than in those with Alzheimer's disease or healthy volunteers (P < .01). VRS scores were significantly higher in patients with vascular dementia than in patients with AD (P < .001), patients with FTD (P < .01), or healthy volunteers (P < .001). VRS scores accounted for 29% of the variance in the regression model, and scores for periventricular hyperintensity accounted for 2%. CONCLUSION: VRS dilatation is common in diseases associated with microvascular abnormality and can be used as a diagnostic tool to differentiate vascular dementias from degenerative dementias.

Aged↗

PubMedDate not supplied

Is volume transfer coefficient (K(trans)) related to histologic grade in human gliomas?

PURPOSE: The purpose of this study was to examine the relationship between contrast transfer coefficient [K(trans)] and grade in gliomas. MATERIAL AND METHODS: Median values of K(trans), CBV(T1), and of the 95th percentile (95%) of the distribution (K(trans) [95%] and CBV(T1) [95%]) were calculated in 39 patients with glioma. Group comparisons and post hoc pairwise comparisons were performed. The relationship between variables and grade used Spearman rho and canonical discriminant analysis. The separation of high- from low-grade tumors was separately assessed by using Mann-Whitney U tests and logistic regression. Receiver operator curve analysis was performed for high- and low-grade tumors and grade III and grade IV tumors. RESULTS: There were significant differences between grades for all variables (P < .001). Pairwise comparisons demonstrated significant differences between grades II and III and II and IV for all variables except K(trans), which did not show significance in the grade II and III comparison, and between III and IV for CBV(T1) and CBV(T1) (95%; P < .01). All variables correlated with grade (P < .01). Discriminant analysis showed independent relation between both CBV(T1) and K(trans) (95%) and grade, and the canonical function produced a total correct classification of 74.4% of cases. Logistic regression analysis for low- versus high-grade tumors showed K(trans) (95%) and CBV(T1) to be independent factors (P < .01 and P < .05). CONCLUSION: There are strong independent relationships between both CBV and K(trans) and histologic grade in gliomas. Both measurements show good discriminative power in distinguishing between low- and high-grade tumors with diagnostic sensitivity and specificity >90%.

Adult↗