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Biomedical subjects

B C Lee

Publications and source records attributed to B C Lee.

At least 73 records · Page 4Linked to original sources
PubMed2000

Inhibitory mechanism of aloe single component (alprogen) on mediator release in guinea pig lung mast cells activated with specific antigen-antibody reactions.

We previously reported that the glycoprotein extracted from aloe strongly inhibited the mediator releases caused by the activation of guinea pig lung mast cells. Therefore, this study aimed to purify a single component that has an antiallergic effect from crude aloe extract and then to assess the effects of aloe single component (alprogen) on the mechanism of mediator releases caused by the mast cell activation. We purified aloe extracts by using various columns. We also purified mast cells from guinea pig lung tissues by using enzyme digestion, rough and discontinuous density Percoll gradient. Mast cells were sensitized with IgG(1) (anti-ovalbumin) and challenged with ovalbumin. Histamine was assayed by using a fluorometric analyzer and leukotrienes by radioimmunoassay. [Ca(2+)](i) level was analyzed by using a confocal laser scanning microscope. Protein kinase activity was determined by the protein phosphorylated with [gamma-(32)P]ATP. The phospholipase D activity was assessed by the labeled phosphatidylalcohol. The amount of mass 1,2-diacylglycerol (DAG) was measured by the [(3)H]DAG produced when prelabeled with [(3)H]myristic acid. Phospholipase A(2) activity was determined by measuring the lyso-phosphatidylcholine released from the labeled phospholipids. Alprogen significantly decreased histamine and leukotriene releases and blocked completely Ca(2+) influx during mast cell activation. The protein kinase C and phospholipase D activities were decreased by alprogen in dose-dependent manner. Alprogen inhibited mass DAG formation and the phospholipase A(2) activity during mast cell activation. The data suggest that alprogen purified from aloe inhibits multiple signals as well as blocking Ca(2+) influx caused by mast cells activated with specific antigen-antibody reactions and that then the inhibition of histamine and leukotriene release follows.

Aloe↗
PubMed1999

Patency and limb salvage for polytetrafluoroethylene bypasses with vein interposition cuffs.

Polytetrafluoroethelene (PTFE) is often utilized in patients with limb-threatening ischemia requiring infrainguinal revascularization in the absence of autologous saphenous vein. To increase long-term patency of PTFE grafts, vein interposition cuffs have been recommended as adjunctive procedures. The purpose of this study was to assess the efficacy of vein interposition cuffs on the long-term patency and limb salvage of patients requiring prosthetic bypass grafts for limb-threatening ischemia. Prosthetic bypass grafts with vein interposition cuffs (PTFE/VC) were performed on 56 limbs in 55 patients (32 men, 23 women; mean age of 67 years) from October 1993 to January 1998. Grafts were prospectively evaluated every 3 months for the first 12 months and biannually thereafter with duplex ultrasonography. PTFE/VC and PTFE bypasses at the popliteal level appear to have comparable patencies. However, PTFE/VC appear to offer an improved patency and limb salvage for infrapopliteal bypasses in patients with critical limb ischemia. When infrapopliteal revascularization is required in the absence of autologous saphenous vein, we recommend the use of PTFE with vein interposition cuffs.

Aged↗
PubMed1999

Effectiveness of rotor off fraction in allogeneic murine bone marrow transplantation with complete disparity of major histocompatibility.

Counterflow centrifugal elutriation (CCE) has been a highly efficient physical method for separating T cells from bone marrow (BM) without impairing cell function and yield. To investigate the usefulness of CCE, the hematopoietic potential as well as the level of T cell contamination in rotor-off (R/O) fraction of BM was studied using a murine bone marrow transplantation (BMT) model [C3H/He (H-2k)-->BALB/C (H-2d)]. The total recovery of cells after CCE procedure was 71.4%. Morphologically, R/O fraction contained abundant mononuclear cells and a few lymphocytes. The numbers of colony forming unit for granulocyte/monocyte (CFU-GM), Sca-1+ cells, and T cells were compared among four fractions of CCE (fractions at flow rate of 17, 25, 28 mL/min, and R/O fraction). The number of CFU-GM per 10(5) nucleated cells in each fraction were significantly higher in R/O fraction (331.3 +/- 34.4) compared to unfractionated marrow (UM) (21.1 +/- 1.3) and fraction of 17 mL/min (FR 17) (23.7 +/- 2.2 ) (chi2 = 0.0044). Neither fraction of 25 mL/min (FR 25) nor fraction of 28 mL/min (FR 28) contained CFU-GM colonies. The concentration of Sca-1+ cells in R/O fraction was significantly higher (1.96-fold) than UM (p < 0.05), and 80.0 +/- 10.1% of Sca-1+ cells in UM were recovered in R/O fraction; 88.1% of Thy-1.2+ T cells were eliminated in R/O fraction (p < 0.05). Mice receiving UM after lethal irradiation (875cGy) suffered from severe graft-versus-host disease (GVHD) and all five died within 7 days after BMT procedure (Group A). Of interest, mice receiving mixture of R/O fraction with lymphocyte-rich fraction (FR 25 plus FR 28) to equalize T cell number as UM, developed severe GVHD and four out of five died (probability of survival; 20%) (Group B). Mice receiving R/O fraction had mild GVHD and four out of five survived for at least 90 days (probability of survival; 80%) (Group C). In group C, probability of survival (p = 0.0006) was higher, and severity of GVHD (p = 0.0043) and progression rate of GVHD (p = 0.02) was lower. In conclusion, the elutriated R/O fraction cells of BM have the advantages of stable engraftment and tolerable GVHD in murine allogeneic BMT with complete major histocompatibility disparity. This could be directly applicable to patients with high risk of GVHD and graft failure in upcoming clinical trials.

Animals↗
PubMed1999

Carotid restenosis: operative and endovascular management.

PURPOSE: Surgical management of carotid restenosis (CR) after carotid endarterectomy (CEA) has been associated with a higher perioperative complication rate than that of primary CEA. We recently used carotid angioplasty-stenting (CAS) as an alternative to operative management in patients who had undergone CEA within three years, and we retrospectively compared these results with those of operative management of CR and the overall results of CEA. METHODS: CEA was performed on 1065 adult patients (58% symptomatic, 42% asymptomatic), 62% of whom were men (n = 660) and 38% of whom were women (n = 405), from 1989 to 1997. Before our initiation of a program of CAS, 16 operative procedures (1.9% of CEAs) were performed for CR in 14 adult patients (7 women and 7 men). During the last 20 months, CAS was used in the management of 17 CRs (16 patients; 9 women and 7 men). RESULTS: The 30-day stroke morbidity-death rate for all CEAs (n = 1065) was 1.4%; 11 strokes (1. 0%) occurred (4 major strokes with disability and 7 strokes with minor or no disability), and 4 deaths (0.4%) occurred (2 deaths caused by myocardial infarction, 1 caused by intracranial hemorrhage, and 1 caused by stroke). Operative management of CR (n = 16) included patch angioplasty in 12 cases (autologous vein patches in 10 cases and synthetic patches in 2 cases), whereas interposition grafting was used in 4 cases (saphenous vein in 3 instances and synthetic [polytetrafluoroethylene] in one case). No strokes or deaths were observed. One recurrent laryngeal nerve palsy occurred (6.2%). Among the 16 patients undergoing 17 CAS procedures, the technical procedures were accomplished in all patients. No strokes or deaths occurred. No recurrent restenoses (50% or greater) have been identified within or adjacent to the CAS procedures. CONCLUSION: CR caused by myointimal hyperplasia can be managed by operative techniques or CAS with comparable periprocedural complications. Although long-term follow-up will be required to determine the incidence of recurrent restenosis, CAS may become the preferred procedure in these cases. A randomized clinical trial ultimately will be necessary to determine the role of CAS, as compared with that of operative management.

Aged↗
PubMed1999

Visual recovery after a year of craniopharyngioma-related amaurosis: report of a nine-year-old child and a review of pathophysiologic mechanisms.

BACKGROUND: The probability of visual recovery in tumor-related optic neuropathy usually correlates with the severity and duration of optic pathway compromise. Recovery of visual acuity to normal levels is unexpected after profound loss of vision extending for a period of weeks and months. METHODS: A 9-year-old girl who had neurosurgical resection of a craniopharyngioma compressing the optic chiasm and optic tract was followed up serially with neuroimaging and clinical examinations over a 6-year period. RESULTS: Within 3 months of the diagnosis of craniopharyngioma, the girl's vision was reduced to no-light-perception blindness when she viewed with the more involved eye. The blindness correlated with an amaurotic (i.e., >3.6 log unit) relative afferent pupillary defect and an absence of any response when tested with visual field perimetry. After more than a year of total blindness and cessation of all neurosurgical and radiation therapy, visual acuity recovered to a normal level (20/25), the afferent pupillary defect improved, and sensitivity in a portion of the temporal hemivisual field was restored. In the follow-up that has extended for 5 years from the time of recovery, stability of the restored vision has been documented. CONCLUSION: Children who have tumor-related loss of vision due to damage to the anterior visual pathways may be capable of recovery after intervals of blindness that would be considered irreversible in adults. The mechanism of the recovery in our patient may have been decompression-related restoration of axoplasmic flow, followed by gradual remyelination of visual fibers, which allowed reorganization of connections to the lateral geniculate nucleus to optimize synaptic transmission.

Blindness↗
PubMed1999

Impaired maximum microvascular hyperaemia in patients with MODY 3 (hepatocyte nuclear factor-1alpha gene mutations).

AIMS: Functional abnormalities of blood flow and capillary pressure may be involved in the pathogenesis of diabetic microangiopathy. Important differences in microvascular behaviour are observed between Type 1 and Type 2 diabetes mellitus, raising the possibility that the pathogenesis of microangiopathy may differ between these. MODY3 patients have hyperglycaemia as a result of genetic defect of beta-cell function rather than increased insulin resistance and are susceptible to microvascular complications and offer an opportunity to examine microvascular behaviour in this setting. METHODS: The maximum microvascular hyperaemic response to local heating of the skin was studied in 12 MODY3 patients and age and sex-matched control subjects using laser Doppler fluximetry. RESULTS: Maximum hyperaemia was reduced in MODY3 patients (median 1.17 (range 0.88-1.92)V vs. 1.70 (1.07-2.19)V normal control subjects; P=0.03) and thus was negatively associated with duration of diabetes (r(s)=-0.79; P = 0.002). CONCLUSIONS: The results suggest that the duration of diabetes is a determinant of impaired microvascular hyperaemia in MODY3 patients. The pattern of vasodilatory impairment is similar to that observed in Type 1 diabetes mellitus and differs from that seen in Type 2 diabetes. This provides support for the concept that beta cell dysfunction and insulin resistance may have differing effects on microvascular behaviour.

Adult↗
PubMed1999

In vitro maturation and in vitro fertilization of bovine oocytes cultured in a chemically defined, protein-free medium: effects of carbohydrates and amino acids.

This study was conducted to examine the effects of carbohydrates and amino acids on the maturation and fertilization of bovine oocytes. To evaluate the effect of each treatment without any unpredictable interference, oocytes were cultured in a simply defined medium (modified Tyrode's medium; mT) without the addition of hormones and proteins. In Experiment 1, oocyte maturation to the metaphase-II stage was significantly (P<0.0001) enhanced after the addition of glucose (5.6 mM), lactate (10 mM) and/or pyruvate (0.5 mM) to mT (37-74%) than after no addition (0%). In mT supplemented with glucose, the addition of 19 essential and non-essential amino acids (aa; 0, 0.01, 0.1, 1, 5 or 10%) did not further improve in vitro maturation (Experiment 2) or in vitro fertilization (Experiment 3) of oocytes. However, more (P<0.05) pronuclear formation after in vitro-insemination was found in oocytes matured in mT with 1% aa and glucose than in oocytes matured in mT with glucose alone (56% vs. 35%). Penetration of spermatozoa into the ooplasm was initiated at 3 h after insemination and pronuclear formation from 8 h (Experiment 4). When cultured inseminated oocytes were examined up to 192 h post insemination, a significant (P<0.05) increase in the number of 2-cell (18 v. 38%) and 8-cell embryos, (7 v. 20%) and morulae (0 v. 8%) was found after the addition of 1% aa to mT with glucose than after no addition (Experiment 5). A limited number of oocytes matured in mT with aa and glucose developed to the blastocyst stage (6%). These results indicate that exogenous carbohydrates and amino acids are prerequisites for the maturation and fertilization of bovine oocytes in vitro. Glucose alone promotes the nuclear maturation of oocytes, whereas amino acids aid the pronuclear formation of fertilized oocytes.

Amino Acids↗
PubMed1999

Hemispheric language dominance in children demonstrated by functional magnetic resonance imaging.

The objective of this study was to demonstrate hemispheric language dominance in normal children. Fifteen normal children were evaluated with functional magnetic resonance imaging (MRI) using an age-related silent word spelling paradigm. The data were analyzed with the cross-correlation method, and lateralization indices were calculated in language regions as determined by Talairach coordinates. Activation foci were detected in the left inferior frontal area and were strongly lateralized, with language lateralization indices of 0.74 +/- 0.21 (age 7-12 years, nine subjects), and 0.79 +/- 0.18 (13-18 years, six subjects). The indices were similar to those for adults (0.83 +/- 0.21, four subjects). Our study established that language is strongly lateralized to the left hemisphere in children as young as 7 years of age.

Adolescent↗
PubMed1999

Hemiballismus-hemichorea in older diabetic women: a clinical syndrome with MRI correlation.

Eight older women from two different continents, all with nonketotic hyperglycemia, presented with hemiballismus-hemichorea (HB-HC) and high signal intensity in the contralateral striatum on T1-weighted MRI scans. Correction of underlying hyperglycemia and supportive care resulted in resolution within days to weeks. This characteristic clinicoradiologic picture suggests a clinical syndrome with benign outcome.

Aged↗
PubMed1999

Echoplanar diffusion-weighted imaging in neonates and infants with suspected hypoxic-ischemic injury: correlation with patient outcome.

OBJECTIVE: Our objective was to examine the effectiveness of echoplanar diffusion-weighted (DW) imaging in detecting CNS ischemia in neonates and infants and to determine how well the imaging findings using this technique correlate with short-term neurologic deficit. MATERIALS AND METHODS: Echoplanar DW images, turbo T2-weighted images, and fluid-attenuated inversion recovery (FLAIR) sequences were obtained in a clinically defined cohort of 26 consecutive neonates and infants with suspected hypoxic-ischemic injury. Echoplanar DW imaging was performed with the diffusion gradient in the slice-select direction: b value, 1200 sec/mm2; matrix, 128 x 128, interpolated to 256 x 256. Four scans (4 sec per scan) were obtained and averaged to optimize the signal-to-noise ratio. Most patients were not sedated (n = 19). Abnormalities seen on DW imaging were correlated with clinical findings at short-term follow-up and compared with findings on FLAIR and turbo T2-weighted images. RESULTS: Short-term clinical follow-up showed neurologic deficit in 10 (83%) of 12 patients with DW images with abnormal findings, and no neurologic sequelae in 12 (86%) of 14 patients with DW images with normal findings. Echoplanar DW images revealed a greater extent of and a larger number of abnormalities compared with FLAIR or turbo T2-weighted images in 11 (92%) of 12 patients with DW images with abnormal findings. CONCLUSION: Echoplanar DW imaging reveals abnormalities poorly depicted on turbo T2-weighted and FLAIR images in neonates and infants with clinically suspected hypoxic-ischemic injury. DW imaging may be able to identify which patients are likely to develop at least short-term neurologic deficits and may afford the best early evaluation of short-term neurologic prognosis in these patients.

Brain↗
PubMed1999

The effects of peripheral leukocytes on the hippocampal neuronal changes in transient global ischemia and unilateral cerebral hemispheric infarction.

The participation of activated leukocytes and subsequent production of chemical mediators has been well accepted in the pathophysiology of hypoxic-ischemic injury. This study was performed to see the effects of leukocytes on hippocampal neuronal damage in transient global ischemia induced by 10-min occlusion of bilateral common carotid arteries (CCAs) with reperfusion for various times, and in complete unilateral ischemia induced by 24-hr ligation of left CCA. Leukopenia was induced by intraperitoneal injection of cyclophosphamide for 4 days. The results showed that hippocampal neuronal damages were worse at 6-hr reperfusion in leukopenic experimental group than in the control group. In comparison, 24-hr and 3-day reperfusion leukopenic groups showed less numbers of damaged neurons and milder changes. The 5-day reperfusion group showed inconsistent changes. Unilateral CCA occlusion showed extensive infarction in 83.3% of gerbils in the control group, compared to 25% of gerbils in the experimental group (p<0.05). These results strongly suggest that the number of peripheral leukocytes were closely related to the development of delayed neuronal damage of hippocampus in transient global ischemia and the incidence of infarction induced by 24-hr unilateral CCA ligation.

Animals↗
PubMed1999

Carcinoma of the axillary breast.

Axillary breast is one of the varieties of polymastia which is characterized by the presence of more than 2 breasts. It may cause symptoms during pregnancy, lactation, or in the premenopausal period. Unless there are obvious symptoms of lactation or the assistance of further imaging studies such as mammography and breast ultrasound, the diagnosis is often confused with subcutaneous lipoma. The incidence of axillary breast cancer is low but it should be investigated and treated properly in view of another breast cancer in the embryonic milk-line. In this paper we reviewed 4 cases of axillary breast cancer and documented some articles regarding aberrant breast and carcinoma arising from it. It is suggested that subcutaneous nodules of uncertain origin around the periphery of the breast should be viewed with suspicion and treated properly.

Adenocarcinoma, Mucinous↗
PubMed1999

MR high-resolution blood oxygenation level-dependent venography of occult (low-flow) vascular lesions.

A new technique for detecting vascular malformations, high-resolution BOLD venography (HRBV), is described. This technique relies on the BOLD principle for detecting deoxygenated blood in low-flow malformations. HRBV images are acquired using a modified 3D gradient-echo with voxel volumes of 0.5 x 0.5 x 2 mm3. The magnitude data are masked with the phase images to enhance visibility of the venous structures and are displayed using the minimum intensity projection. Preliminary results for 10 patients show that HRBV is more sensitive in detecting cavernomas than is T2-weighted imaging, and lesions that are presumed to be telangiectasias are detected only with this technique.

Brain↗
PubMed1998

High-resolution venography of the brain using magnetic resonance imaging.

The purpose of this study was to evaluate a non-flow related magnetic resonance imaging method to visualize small veins independent of arteries in the human brain. A long TE, high-resolution 3D gradient echo MR acquisition was used to highlight venous information. The method is based on the paramagnetic property of deoxyhemoglobin and the resulting phase difference between veins and brain parenchyma at long echo times. The MR magnitude images were masked with a phase mask filter to enhance small structure visibility. Venous information down to sub-pixel vessel diameters of several hundred microns is visible. Venous data are displayed in an angiographic manner using a minimum intensity projection algorithm. Both superficial veins and deep white matter veins are visible. The method has been successfully applied in volunteers. Preliminary results in patients with cerebral arteriovenous malformations indicate its potential in clinical applications. The proposed method is easy to implement and does not require administration of a contrast agent or application of specially designed rf pulses to highlight the veins. Rather it exploits the intrinsic magnetic properties (BOLD-effect) and the prolonged T2* of venous blood. The method may be of diagnostic potential in the assessment of arteriovenous malformations or other vascular venous lesions.

Adolescent↗