Search PubMed⌕ Search

Biomedical subjects

M Scanlon

Publications and source records attributed to M Scanlon.

51 records · Page 3Linked to original sources
PubMed1987

Magnetic resonance imaging after corpus callosotomy.

Magnetic resonance imaging (MRI) can visualize the extent of corpus callosotomy performed for medically intractable epilepsy not amenable to focal surgery. Five patients underwent complete callosotomy and one an anterior callosotomy, aged 19 to 24 years, 21 to 53 months (prior to scanning). T1 images showed complete absence of the callosal shadow in five cases and visualization of the genu and splenium in the sixth case. T2-weighted pulse sequence spin-echo MRI showed intense image throughout the region of the entire callosum in the two cases with the longest postoperative course. The two middle cases showed intense T2 signal from the splenium, and the two latest showed no increase in T2 signal. We believe the increase in T2 signal in the transected callosum may represent an in vivo example of anisomorphic gliosis. T1 images demonstrate the anatomic extent of transection, while T2 images demonstrate the chemical and pathophysiologic sequence of transection. Thus, MRI is the imaging test of choice to evaluate callosotomy patients.

Adolescent↗
PubMed1980

Diagnosis of viral infections by multicomponent mass spectrometric analysis.

Metabolic profiles of urine extracts of humans with viral infections, as well as of media of virus-infected human tissue cultures, have been analyzed by non-fragmenting mass spectrometry and compared with corresponding controls. The spectra were then subjected to several alternative computerized statistical procedures to detect diagnostic biochemical profiles. Controlled longitudinal studies on fully informed, consenting volunteers who received sandfly fever virus demonstrate the onset of a characteristic metabolic pattern that precedes the onset of symptoms and subsides when the patients overcome the infection. Longitudinal studies of human tissue cultures infected with poliomyelitis virus demonstrate characteristic metabolic patterns within a few hours after infection. Non-fragmenting mass spectrometry may thus provide the clinical laboratory with a sensitive, reliable test for viral infections significantly faster than attainable by current techniques.

Bunyaviridae↗
PubMedDate not supplied

GH responses to growth hormone releasing factor in depression.

The growth hormone (GH), thyrotrophin (TSH) and prolactin response to growth hormone releasing factor (GRF) was investigated in 18 patients suffering from major depression with melancholia and in 18 age- and sex-matched normal controls. There was no significant difference in the GH response to GRF stimulation between the patients and controls and in neither subject group was there a demonstrable TSH or prolactin response to GRF. These findings indicate that the pathophysiology underlying the blunted GH response to pharmacological challenge, demonstrated in other studies, must lie at a suprapituitary level.

Depressive Disorder↗
PubMedDate not supplied

Calcium and hydrogen ion concentrations in the parasitophorous vacuoles of epithelial cells infected with the microsporidian Encephalitozoon hellem.

Microsporidia of the genus Encephalitozoon undergo merogony and sporogony in a parasitophorous vacuole within the host cell. Cultured green monkey kidney cells infected with Encephalitozoon hellem were loaded with the fluorescent dyes fura-2 or BCECF in order to measure intracellular concentrations of calcium and hydrogen ions respectively. Both the parasitophorous vacuole calcium concentration and pH values resembled those of the host cell cytoplasm in infected cells. Calcein entered the parasitophorous vacuole but not other host cell vacuoles or parasite stages within the parasitophorous vacuole. The lack of a pH or calcium concentration gradient across the parasitophorous vacuole membrane and the permeability of this membrane to a large anion such as calcein suggest that the vacuole membrane surrounding E. hellem resembles that surrounding some other intracellular parasites such as Toxoplasma gondii. A potential role is discussed for the parasitophorous vacuole calcium concentration in germination in situ.

Animals↗
PubMedDate not supplied

Infection by microsporidia disrupts the host cell cycle.

Microsporidia of the genus Encephalitozoon infect mammalian cells and have become a source of morbidity and mortality in immunocompromised humans. Encephalitozoon microsporidia develop and mature within parasitophorous vacuoles, enlarging the vacuole over time until it eventually occupies most of the cytoplasm of the host cell. The ability of the host cell to accommodate such a large burden for several days suggests that the parasite subverts normal host cell processes to ensure optimal environmental conditions for its growth and development. Since this environment would be threatened if cell division of the host cell occurred, we have formulated the hypothesis that infection with Encephalitozoon microsporidia induces an arrest in the cell cycle of the host cell. In support of this hypothesis, we have found that mitotic index and DNA duplication are reduced in infected cells as compared to uninfected cells. The number of host cell nuclei in S phase is increased. The levels of cyclin D1 and the percentage of cells in G1 are reduced; however, the levels of cyclin B1 are elevated even though the percentage of cells in G2/M is decreased. These results suggest that host cells infected with Encephalitozoon microsporidia are blocked at multiple points in the cell cycle.

Animals↗
PubMedDate not supplied

Binswanger's disease: some neuropsychological considerations.

The literature regarding Binswanger's disease is reviewed. Emphasis is placed on reviewing the neuropsychological literature related to Binswanger's disease. In addition, a retrospective analysis was carried out among four groups of subjects (N = 61) who were divided according to the presence or absence of dementia and deep white-matter alterations. A main effect for deep white-matter alterations was found for almost all measures of diastolic and systolic blood pressure. Among the two nondemented groups there was an effect of deep white matter alteration on neuropsychological functioning. Subjects with deep white matter changes performed worse on tests of immediate and delayed recall of a prose passage. Among the two demented groups there were no differences on any of the neuropsychological measures, although subjects with deep white matter alterations exhibited a higher incidence of focal neurologic signs and stroke. We conclude that Binswanger's disease is probably more prevalent than currently appreciated. Also, among clinically nondemented individuals periventricular white-matter alterations may be associated with subtle but definable neuropsychological deficits, and these individuals may be at risk for developing a dementing illness.

Aged↗
PubMedDate not supplied

Expression of thyrotropin-releasing hormone messenger RNA in human pituitary adenomas with follicle-stimulating hormone immunoreactivity.

OBJECTIVE: To assess the correlation between thyrotropin-releasing hormone (TRH) messenger RNA (mRNA) and the immunoreactive type of human pituitary adenomas. METHODS: Twenty-eight patients (14 to 73 years old) who had pituitary adenomas (18 nonfunctioning adenomas, 8 growth hormone-secreting adenomas, and 2 prolactinomas) underwent surgical treatment. Pituitaries removed at autopsy from four patients without evidence of pituitary disease were used as controls. Fragments of pituitary adenomas were processed for TRH mRNA by in situ hybridization (radioactive and nonradioactive) and for TRH peptide and anterior pituitary hormones (b-thyrotropin, b-follicle-stimulating hormone [FSH], bluteinizing hormone [LH], prolactin, and growth hormone) by immunohistochemistry with use of the avidinbiotin technique. Quantitative immunohistochemical studies were performed by using image analysis software. The signal was considered positive when more than 5% of the cells were stained. RESULTS: Cells expressing TRH mRNA were detected in 22 of 28 pituitary adenomas--15 of 18 nonfunctioning pituitary adenomas, 5 of 8 growth hormone-secreting adenomas, and both prolactinomas. TRH peptide was revealed in only 10 adenomas, all expressing TRH mRNA as well. All but one nonfunctioning adenoma expressing TRH mRNA in more than 5% of the cells were b-FSH immunoreactive (15 of 16 cases; P<0.005, c 2 test), whereas only 6 of 16 nonfunctioning adenomas exhibited both b-thyrotropin and TRH mRNA and only 5 of 16 were positive for both b-LH and TRH mRNA. CONCLUSION: These results confirm previous data demonstrating the presence of TRH mRNA and TRH peptide in human pituitary tumor cells. We further showed that the presence of TRH mRNA is significantly correlated with FSH immunoreactive gonadotropinomas. The release of FSH after an intravenous TRH test only in gonadotropinomas, together with local production of TRH, suggests a role for TRH in pathogenesis.

Journal Article↗