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Biomedical subjects

M Castillo

Publications and source records attributed to M Castillo.

At least 91 records · Page 5Linked to original sources
PubMed1998

Normal cross-sectional anatomy of the nasopharynx, oropharynx, and oral cavity.

The anatomy of the extracranial head and neck is complex and difficult to understand. In contrast to other regions, the majority of lesions involving the upper aerodigestive tract (pharynx and oral cavity) are either visible on endoscopy or palpable on clinical examination. This article describes the normal cross-sectional computed tomography and magnetic resonance imaging anatomy of the upper aerodigestive tract.

Humans↗
PubMed1998

Usefulness of contrast material in MR of patients with neurofibromatosis type 1.

PURPOSE: Our objective was to determine the usefulness of routine administration of contrast material in brain MR imaging for the evaluation of areas of probable myelin vacuolization and neoplasms in patients with neurofibromatosis type 1 (NF-1). METHODS: We retrospectively reviewed 112 consecutive contrast-enhanced brain MR studies obtained over a period of 7 years in 109 symptomatic and asymptomatic patients compiled from two institutional NF-1 data bases. MR studies were analyzed for areas of probable myelin vacuolization, with attention to degree of enhancement and its impact on lesion detection and characterization. Usefulness of contrast material was graded as 0 = not useful, 1+ = somewhat useful, and 2+ = useful. RESULTS: Of 112 studies, 45% (n = 49) were normal. In the remaining 63 studies, 88 regions of probable myelin vacuolization and 52 tumors were identified. Enhancement was not observed in any regions of probable myelin vacuolization. Enhancement was present in 31% of tumors, and, of these, was found to be useful in 44%, somewhat useful in 12%, and not useful in 44%. For enhancing tumors, contrast agent was useful for lesion detection in 19% and for lesion characterization in 25%. CONCLUSION: Contrast administration is useful in baseline MR studies to maximize tumor detection and characterization, to add confidence to the diagnosis of benign probable myelin vacuolization, and to document stability of neoplasms on follow-up examinations.

Adolescent↗
PubMed1998

Spinal intradural cerebellar ectopia.

An ectopic cerebellum, as in Chiari malformations and ectopic cerebellar dysplastic tissue, is a common finding; however, the presence of an organized ectopic cerebellum is exceedingly rare. We describe the MR imaging, surgical, and histologic appearance of an intraspinal ectopic cerebellum in an infant.

Cerebellum↗
PubMed1998

Proton MR spectroscopy of common brain tumors.

Proton MR spectroscopy allows differentiation of normal tissues from pathologic ones. There is now evidence that this technique may be able to distinguish different histological grades of tumors. The proton MR spectroscopic changes due to treatment of brain tumors is discussed in this article.

Brain Neoplasms↗
PubMed1998

Proton MR spectroscopy in psychiatric and neurodevelopmental childhood disorders: early experience.

Variations in brain morphology are increasingly being found in patients with psychiatric disorders. There is early evidence that some metabolic abnormalities may also be present in these patients. In many patients with psychiatric disorders, the diagnosis is not straight forward and may be confounded by co-morbid processes. Establishing the correct diagnosis is important as it leads to institution of appropriate therapies. Descriptions of the authors early experience using proton MR spectroscopy in the evaluation of children with bipolar affective disorder, attention deficit hyperactivity disorder, neurodevelopmental abnormalities in patients with neurofibromatosis type 1, and the effects of certain types of treatment used for these disorders are discussed.

Attention Deficit Disorder with Hyperactivity↗
PubMed1997

Regulation of mevalonate 5-pyrophosphate decarboxylase in HeLa cells. Inhibition of enzymatic protein synthesis by serum lipoproteins.

Mevalonate 5-pyrophosphate decarboxylase (EC 4.1.1.33) has been considered as a secondary site of regulation of cholesterogenesis. Because of this, we have studied the regulation of decarboxylase in HeLa cells by serum lipoproteins in the cell culture medium. A first group of experiments was performed with cells grown in Eagle's medium with 10% foetal calf serum. The specific activity of decarboxylase was increased when whole foetal calf serum was replaced with lipoprotein-poor serum. This increase was clearly reduced in the presence of cycloheximide. Addition of serum lipoproteins to a medium containing lipoprotein-poor serum led to a clear decrease in the decarboxylase activity. An identical decrease was observed after the addition of lipoproteins alone or in combination with cycloheximide. These results suggest for the first time that the effect of serum lipoproteins on decarboxylase activity should be a decrease in the rate of enzymatic protein synthesis, and corroborate the important role of reactions other than those catalysed by 3-hydroxy-3-methylglutaryl-CoA reductase in the regulation of cholesterogenesis.

Blood Proteins↗
PubMed1997

Enhancement of paclitaxel activity against hormone-refractory prostate cancer cells in vitro and in vivo by quinacrine.

Cytoplasmic phospholipase A2 (PLA2) is known to be phosphorylated and activated by MAP kinase (Lin et al 1993, Cell 72: 269-278), an important downstream component of signal transduction, whereas paclitaxel has been shown to inhibit isoprenylation of ras proteins (Danesi et al 1995, Mol Pharmacol 47: 1106-1111). Given that quinacrine (Q), a PLA2 inhibitor, and paclitaxel (P) might act at different sites in the cell signalling pathway, our aim was to test whether they were synergistic in combination against prostate cancer cells. Cell viability of PC-3, PC-3M and DU145 cells in 96 - well plates was assessed 96 h after drugs were added concurrently. Using Chou analysis, we demonstrated synergy for the combination against all three cell lines. Further, synergy was present under both conservative (mutually non-exclusive) and non-conservative (mutually exclusive) models. Studies in the nude mouse xenograft model support the finding of synergy in vitro. In DU145-bearing mice, Q (50 mg kg(-1)) and P (0.5 mg kg(-1)) given daily for 12 consecutive days, either concurrently or sequentially, was more effective than either drug alone, at twice the dose intensity. In an enzyme-linked immunosorbent (ELISA) apoptosis assay, arachidonic acid was able to partially reverse Q- and P-induced apoptosis, suggesting PLA2 pathway involvement. Finally, the combination of lovastatin, another inhibitor of ras isoprenylation, and quinacrine had synergistic inhibitory effects on the growth of PC-3 cells in vitro, suggesting that the combination of these two classes of compounds might serve as an attractive therapeutic approach for prostate cancer.

Animals↗
PubMed1997

Papillary endolymphatic sac tumors: CT, MR imaging, and angiographic findings in 20 patients.

PURPOSE: To determine the computed tomographic (CT), magnetic resonance (MR) imaging, and angiographic findings of papillary endolymphatic sac tumors. MATERIALS AND METHODS: Clinical and imaging studies in 20 patients (aged 17-65 years) with histopathologically proved papillary endolymphatic sac tumors were retrospectively reviewed. Patients underwent CT (n = 18), MR imaging (n = 15), or angiography (n = 12). CT scans were evaluated for bone erosion and calcification; MR images, for signal intensity, enhancement patterns, and flow voids; and angiograms, for tumoral blood supply. RESULTS: All tumors were destructive and contained calcifications centered in the retrolabyrinthine region at CT. The MR imaging appearance varied with lesion size; 12 of 15 tumors showed increased signal intensity at T1-weighted imaging. The high-signal-intensity area was circumferential in lesions 3 cm or smaller and was scattered throughout the lesion in advanced tumors. Only tumors larger than 2 cm had flow voids. The blood supply arose predominantly from the external carotid artery. Large tumors had additional supply from the internal carotid and posterior circulation. CONCLUSION: Papillary endolymphatic sac tumors are destructive, hypervascular lesions that arise from the temporal bone retrolabyrinthine region. Increased signal intensity at unenhanced T1-weighted MR imaging is common and may help distinguish these lesions from more common, aggressive temporal bone tumors.

Adenocarcinoma↗
PubMed1997

Comparison of CT and MR features with clinical outcome in patients with Rocky Mountain spotted fever.

PURPOSE: To compare neuroimaging findings and clinical features in patients with Rocky Mountain spotted fever and to determine the impact of imaging studies in the treatment of these patients. MATERIALS: We reviewed the brain CT scans (n = 44), MR images (n = 6), or both (n = 4), and one MR spinal study in 34 patients with Rocky Mountain spotted fever, proved by definitive serologic criteria. Records were reviewed with attention to clinical symptoms and therapeutic modifications based on neuroimaging; outcomes were compared with imaging findings. RESULTS: Abnormalities, consisting of infarctions, cerebral edema, meningeal enhancement, and prominent perivascular spaces, were found on four of 44 CT scans and on four of six MR studies. The spinal MR study showed abnormal enhancement of the lower spinal cord and cauda equina. Nonspecific clinical symptoms were present in all patients in whom neuroimaging findings were abnormal and in 80% of patients whose CT and/or MR findings were normal. After treatment, return to baseline clinical status was documented in 67% of patients with abnormal imaging findings and in 93% with normal findings. Death occurred in 17% of patients with abnormal neuroimaging results and in none of those with normal results. CONCLUSIONS: Abnormalities on neuroimaging studies were not common in patients with Rocky Mountain spotted fever. When present, they were subtle. Symptoms at presentation and unfavorable outcomes were more prevalent when CT or MR findings were abnormal. Abnormalities identified on neuroimaging studies did not alter clinical treatment in any patient.

Adolescent↗
PubMed1997

Imaging findings in patients with clinical anophthalmos.

PURPOSE: To review the intracranial and facial imaging features in children with congenital anophthalmos. METHODS: We retrospectively studied eight children with anophthalmos with respect to intraorbital, intracranial, and craniofacial anomalies (six had CT examinations, including the face, orbits, and brain, and four had MR imaging, including the orbits and brain). RESULTS: Three patients had primary bilateral anophthalmos on CT (n = 1) and MR (n = 3) studies. In these patients, MR images showed hypoplasia of the optic chiasm and posterior visual pathways (n = 3), agenesis (n = 1) or dysgenesis of the corpus callosum (n = 2), and a mass in the tuber cinereum region (n = 1). One patient had incontinentia pigmenti. Five patients had unilateral anophthalmos on CT (n = 5) and MR (n = 1) studies. One of these patients had a contralateral congenital cystic eye and one had contralateral severe microphthalmia and absent optic chiasm. All had craniofacial anomalies that consisted of midline facial clefts (n = 2) and concomitant hemifacial hypoplasia (n = 2). One had a craniosynostosis. All five had normal-appearing brains. CONCLUSION: Patients with bilateral anophthalmos represent a distinct group from those with unilateral anophthalmos. In our patients, bilateral anophthalmos was associated with absence of the optic chiasm, diminished size of the posterior optic pathways, and agenesis or dysgenesis of the corpus callosum. Patients with unilateral anophthalmos had severe craniofacial anomalies. Imaging of the face is helpful in patients with unilateral anophthalmos.

Agenesis of Corpus Callosum↗
PubMed1997

Choristomas of the seventh and eighth cranial nerves.

Choristomas, masses of normal tissues in aberrant locations, contain smooth muscle fibers and fibrous tissues. We describe the MR imaging features of two choristomas located in the internal auditory canals and arising from the facial and vestibulocochlear nerves. Both lesions enhanced with contrast material. In one case, enhancement was seen in the geniculate ganglion and greater superficial petrosal nerve. In the other, a medial component enhanced less than the lateral component did.

Adult↗
PubMed1997

Postmortem MR imaging of the brains of patients with AIDS.

Forty-two postmortem formalin-fixed brains of known patients with AIDS were examined with T2-weighted MR imaging before brain cutting. The gross and microscopic brain findings were correlated with the T2 signal changes in the postmortem MR imaging. The brains included examples of progressive multifocal leukoencephalopathy with involvement of the central brain and cerebellum. The authors also encountered the coexistence of progressive multifocal leukoencephalopathy and HIV encephalitis, and the T2 signal changes for each were compared. The T2 signal changes of leptomeningeal and perivascular space cryptococcal infection and CMV ependymitis are documented. Several expressions of primary cerebral lymphoma, including large nodules, choroid plexus infiltration, and diffuse microscopic sites of tumor also are assessed.

AIDS-Related Opportunistic Infections↗