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Biomedical subjects

B C Lee

Publications and source records attributed to B C Lee.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

The effect of PDE5 inhibition on the erectile function in streptozotocin-induced diabetic rats.

The aim of this study was to assess the effect of phosphodiesterase 5 inhibitor, DA-8159, on erectile function throughout the quantitative analysis of vascular endothelial cell, smooth muscle (SM), TGF-beta1 expression in rat corpus cavernosum and measurement of intracavernous pressure (ICP) in diabetic rats. DA-8159 (0, 5, 10, 20 mg/kg) was administered orally once a day to diabetic rats. After 8 weeks, immunohistochemistry and computerized image analysis were performed to quantify the percent area within the Corpora Cavernosa occupied by the endothelial cells, SM cells and fibrotic tissues. ICP/mean arterial pressure (MAP) was also measured by electrostimulation of the cavernous nerve. Diabetic rats showed a significant decrease in the SM and endothelial cell content, and an increase in the TGF-beta1 expression level within the cavernosa areas compared to the normal rats. The mean cavernous SM, endothelial cell content and TGF-beta1 expression level were 9.7+/-0.7, 4.5+/-0.7 and 17.9+/-2.1%, respectively. DA-8159 prevented reduction of SM (12.3+/-0.4% (5 mg/kg), 13.8+/-0.4% (20 mg/kg)) and endothelial cell content (5.6+/-0.5% (5 mg/kg), 6.3+/-0.6% (20 mg/kg)). Immunoreactivity of TGF-beta1 and intracorporal fibrosis were also significantly lower in DA-8159-treated groups (11.8+/-1.2% (5 mg/kg), 9.5+/-1.1% (20 mg/kg)). Electrostimulation of the cavernous nerve induced significant increase in maximum ICP (62.2+/-13.6 mmHg in 10 mg/kg vs 37.5+/-17.5 mmHg in diabetic group) and area under the curve of the ratio of ICP/MAP (8891.09+/-1957 in 10 mg/kg vs 6315.87+/-2272 in diabetic group). These results suggest that subchronic treatment of DA-8159 can prevent the development of erectile dysfunction (ED), and provides a rationale for the use of DA-8159 as treatment of diabetic ED.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMedDate not supplied

Prolonged ictal amnesia with transient focal abnormalities on magnetic resonance imaging.

A previously healthy woman had a prolonged amnestic state caused by complex partial status epilepticus with bilateral mesiotemporal lobe involvement confirmed by EEG with nasopharyngeal electrodes. A magnetic resonance imaging (MRI) scan obtained shortly after recovery from the amnesia showed reversible focal abnormalities consisting of increased signal intensity on T2-weighted scan in the mesiotemporal lobe.

Adult↗
PubMedDate not supplied

New cosmetic agents for skin whitening from Angelica dahurica.

To develop a new whitening agent for cosmetics from natural products, Angelica dahurica was selected for its inhibitory effect on melanogenesis in B16 melanoma cells. From the mechanism study, it was clarified that the ethanolic extracts of this plant showed the suppression of tyrosinase synthesis but no inhibition of tyrosinase activity. In order to find the active constituents from this plant, the ethanol extracts were chromatographed repeatedly with silica gel. Two coumarin compounds were isolated from A. dahurica. Their structures were identified by physicochemical and spectral data such as UV, IR, NMR, and MS. It was shown that the active substance was isoimperatorin (10-[(3-methyl-2-butenyl)oxy]-7H-furo[3,2-g][1] benzopyran-7-one) and imperatorin (9-[(3-methyl-2-butenyl)oxy]-7H-furo[3,2-g][1] benzopyran-7-one). They significantly inhibited tyrosinase synthesis in B16 melanoma cells. To elucidate the action mechanism of the active compounds of A. dahurica, we investigated the changes in the mRNA level of tyrosinase using the RT-PCR technique. As a result, the mRNA level of tyrosinase was markedly reduced by active compounds of A. dahurica. From these results, we suggest that these extracts might be useful as a new whitening agent in cosmetics, but the in vitro findings must be verified in in vivo skin-lightening studies.

Angelica↗
PubMedDate not supplied

Inhibitory effects of antioxidant constituents from Melothria heterophylla on matrix metalloproteinase-1 expression in UVA-irradiated human dermal fibroblasts.

Matrix metalloproteinases (MMPs) are known to play an important role in photoaging by mediating the degradation of extracellular matrix proteins. To develop a new anti-aging agent for cosmetics from natural products, Melothria heterophylla (Lour.) Cogn. was selected for its antioxidant activity and inhibitory effect on expression of MMP-1 in UVA-irradiated human skin fibroblasts. Two compounds (compounds 1 and 2 ) were isolated from an ethyl acetate soluble fraction of the ethanolic extracts; they were identified as 1,2,4,6-tetra-O-galloyl-beta-(D)-glucopyranose (1) and 3,4,5-trihydroxybenzoic acid (2). These compounds were found to scavenge radicals and reactive oxygen species (ROS) and were measured to have SC50 values of 3.9 microM and 13.3 microM against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and values of 4.3 microM and 4.0 microM against superoxide radicals in the xanthine/xanthine oxidase system, respectively. Compounds 1 and 2 showed a dose-dependent inhibitory effect on the expression and activity of MMP-1 in UVA-induced human skin fibroblasts, but no inhibition of MMP-1 mRNA expression. Therefore, we concluded that compounds 1 and 2 significantly inhibited MMP-1 expression at the protein level. Also, these compounds were determined to have a potent antioxidant activity. From these results, we suggest that these compounds might be useful as a new anti-aging agent for photodamaged skin, but the in vitro findings must be verified in in vivo studies.

Antioxidants↗
PubMedDate not supplied

MR recognition of supratentorial tumors.

Eighty patients with intrinsic tumors of the cerebral hemispheres and thalami were studied with a 0.5 T superconducting system and third- or fourth-generation computed tomographic (CT) scanners. Twenty-eight patients had histologically verified gliomas, 34 were presumed to have primary brain tumors on clinical grounds, 13 had metastases, and five were postoperative. Lesions shown on CT were equally well demonstrated on magnetic resonance (MR) imaging; more metastases were seen on MR than on CT images. MR revealed abnormal signals in 10 cases in which CT findings were equivocal. It was not possible to differentiate edema from tumor in many cases using the MR imaging sequences currently available. The histologic types of the tumors could not be determined from the MR appearances.

Brain Neoplasms↗
PubMedDate not supplied

MRI of optic chiasm and optic pathways.

Eight verified lesions of the optic chiasm were examined on 0.5 T magnetic resonance (MR) and GE 9800, 8800 computed tomographic (CT) scanners. Enlargement of the optic chiasm was demonstrated in all cases. There was some change of MR signal compared with brain in all but one case, which had no resemblance to contrast enhancement on CT scans. The signal was specific for hematoma in one case. Abnormal signal, probably signifying tumor spread into the optic radiation, was detected on T2-weighted images in one case. The resolution of MR scans is similar or superior to CT, and sagittal views are most useful in evaluating lesions in this location.

Adolescent↗
PubMedDate not supplied

MRI of the central nervous system in neonates and young children.

Twelve normal neonates and young children, ages 32 weeks gestation to 20 months, and 22 abnormal children up to four years old had MRI scans using a 0.5 T superconducting scanner. A faint signal that was presumed to be myelin was detected in the thalami at 32 weeks; myelination of the occipital lobes was present at full term, and visible throughout the hemispheres by 8 weeks of age. Anatomical locations of congenital lesions were well demonstrated, especially in sagittal views. The signal changes of perinatal abnormalities, such as hemorrhage and hemiatrophy, were often specific. Abnormal position of the spinal cord, spinal lipomas, and other congenital lesions were also well visualized.

Agenesis of Corpus Callosum↗
PubMedDate not supplied

MR of lissencephaly.

Explore the source record for details and available documents.

Cerebral Cortex↗
PubMedDate not supplied

Magnetic resonance imaging of meningiomas.

Twenty-eight patients with 32 meningiomas were studied on a 0.5-T superconductive magnetic resonance (MR) imager. This common, benign treatable tumor was more clearly seen on computed tomography (CT) than MRI in 53% of cases. This is a result of poor contrast between the tumor and the adjacent brain on all spin-echo and inversion-recovery pulse sequences. Those sequences that provide the greatest anatomic detail were best for identifying this low-contrast lesion. Inversion-recovery scans in particular demonstrated the tumor as a discrete hypointense mass (relative to nearby white matter) with excellent visualization of the dural base and white matter buckling indicative of extracerebral mass effect. Other characteristic features include: a hypointense rim because of the venous capsule (66%); mottling due to hypervascularity; a well defined edema collar that demarcates the tumor from adjacent brain; and hyperostosis with thickening of the calvaria and obliteration of its normal landmarks. MRI did not demonstrate tumor calcification but did demonstrate vascular encasement, displacement, and occlusion better than CT and as well as digital venous angiography.

Adult↗
PubMedDate not supplied

MR imaging of brainstem tumors.

Eighteen patients aged 4-72 years old with brainstem tumors were studied using a 0.5 T magnetic resonance (MR) imager and a third- or fourth-generation computed tomographic (CT) scanner. MR imaging showed the brainstem to be enlarged on sagittal views in all cases; exophytic growth was seen in eight. Alterations of signal intensities were shown in most cases on spin-echo sequences using 30 and 90 msec echo times and inversion recovery techniques. It was not possible to distinguish primary from metastatic tumors. The configurations and margins of the areas with abnormal signal did not appear to correlate with the clinical behavior of the tumors. CT was able to recognize brainstem tumor in only 13 of 16 cases. In the two cases of metastases, plain CT scans were normal, but enhancement was seen after administration of contrast material in one. It appears that MR imaging is sensitive in detecting tumor enlargement and abnormal signals and is superior to CT in evaluating brainstem tumors.

Adolescent↗
PubMedDate not supplied

MR imaging of the craniocervical junction.

Craniocervical junctions in 35 abnormal and 10 normal subjects were studied with a 0.5 T superconducting magnetic resonance imaging system. Sagittal spin echo with 30 msec echo times and 500 msec repetition times constituted the most informative imaging plane and sequence. The anterior aspect of the foramen magnum was well delineated; the posterior margin was less constant in appearance. Compression and distortion of the medulla and upper cervical cord by bony and extramedullary lesions were seen easily. Intramedullary cysts were differentiated from solid tumors, but ventricular communication was evaluated less successfully because of partial-volume effect of the sections. Cerebellar ectopias were detected in some asymptomatic patients.

Arachnoid↗
PubMedDate not supplied

MR imaging of cerebral vascular malformations.

Fifteen vascular malformations, including six supratentorial arteriovenous malformations (AVMs), three venous malformations, and six brainstem vascular malformations, were examined on 0.5 T magnetic resonance (MR) and GE 9800 and 8800 computed tomographic (CT) scanners. All the malformations were shown by MR, and the arterial and venous drainage of AVMs was precisely delineated. Hematoma was always differentiated from calcification by MR signal characteristics. Increased signal in the brain parenchyma was often seen adjacent to AVMs. The signal of blood within venous malformations altered with spin-echo techniques using various repetition times and was distinguished from rapidly flowing blood in AVMs that lacked signal in all imaging sequences. Brainstem malformations were seldom demonstrated by angiography. Hemorrhage was common and was invariably associated with multiple areas of absent signal that may have represented abnormal vessels. These appearances are distinct from those of intrinsic tumors and are probably pathognomonic of brainstem vascular malformations.

Brain↗
PubMedDate not supplied

Quantification of gray/white matter in neonates and adults.

Quantitation of gray/white matter is important in evaluation of cerebral blood flow, atrophy, and development of the brain. First-order statistical analysis of neonatal computed tomographic (CT) images revealed that there was only a 6 Hounsfield unit (H) difference between gray and white matter compared with the observed 3 H for the standard deviation over the field of a skull water phantom. Scene segmentation methods based on first-order statistics proved unsuccessful in separating gray and white matter. A new regional clustering algorithm based on local textural properties was developed for separation of these structures.

Adult↗
PubMedDate not supplied

Digital intravenous cerebral angiography in neonates.

Digital intravenous cerebral angiography was performed in 13 neonates. Injections were made either centrally into the right atrium or peripherally into a distal vein. Seven infants suffered from anoxia, one infant had clinical brain death, another had focal infarcts, and two had intracranial hemorrhage. One infant had an intracranial tumor and another had a neck tumor. Venous sinus thrombosis was seen in five of the seven anoxic infants. A total absence of intracranial arterial circulation was demonstrated in the clinically brain-dead infant. Vascularity and venous involvement by neoplasm were excellently delineated by this technique.

Brain Diseases↗
PubMedDate not supplied

CT of acquired immunodeficiency syndrome.

Thirty patients with acquired immunodeficiency syndrome were examined by computed tomography. In addition to systemic disease, these patients had a variety of neurologic symptoms and signs. Cerebral toxoplasmosis (six cases) was generally manifested by ring-enhancing lesions with surrounding decreased attenuation. Lymphoma (one case) exhibited a solid enhancing nodule, and progressive multifocal leukoencephalopathy (two cases) showed periventricular decreased attenuation. Atrophy (15 cases) was very common and invariably indicated a poor prognosis; the autopsy examinations of the latter cases showed degeneration of gray and white matter with features similar to cytomegalic inclusion encephalitis and subacute sclerosing encephalopathy of measles.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Plain and metrizamide CT of lumbar disk disease: comparison with myelography.

Computed tomography with and without administration of intrathecal contrast material was evaluated in 100 patients with suspected lumbar disk disease. Metrizamide computed tomography was performed in 75 patients and plain computed tomography was performed in 25. Metrizamide computed tomography was more accurate than plain computed tomography. It also disclosed many lesions not shown by metrizamide myelography at the lumbosacral level. Very few lesions were revealed by myelography that were not seen by metrizamide computed tomography. The small amount of intrathecal metrizamide needed for scanning has practically no side effects. Experience in 12 patients indicates that the procedure may be performed safely on an outpatient basis. This study suggests that computed tomography should be given serious consideration as the primary definitive radiographic examination of suspected lumbar disk disease.

Humans↗