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Biomedical subjects

W B Lee

Publications and source records attributed to W B Lee.

At least 19 recordsLinked to original sources
PubMed2002

Biodegradation of gaseous benzene with microbial consortium in a biofilter.

The objective of this study was to investigate the biodegradation of gaseous benzene in a biofilter inoculated with benzene-oxidizing microorganisms. The biofilter performance was monitored in terms of benzene removal efficiency and carbon dioxide production. The biofilter was capable of achieving as much as 96% benzene removal efficiency at a residence time of 2 min and an inlet concentration of 220 ppm. During operation with an inlet benzene of 220 ppm, the maximum elimination capacity of the biofilter was 483 g of C6H6 m(-3) day(-1). Under the same conditions, carbon dioxide with a concentration of up to 726 ppm was produced. It was found that carbon dioxide wasproduced at a rate of 608 mg day(-1), which corresponded to a volume of 0.35 l day(-1). Observable features of the microorganisms, meaning microbial activity occurrence in the biofilter, were investigated with the microscopy analysis.

Bacteria↗
PubMed2001

Estrogen attenuates cell death induced by carboxy-terminal fragment of amyloid precursor protein in PC12 through a receptor-dependent pathway.

In the present study, we investigated effects of estrogen on cell death induced by carboxy-terminal fragment of amyloid precursor protein (CT), a candidate causative substance in the pathogenesis of Alzheimer's disease. 17 beta-Estradiol attenuated CT-induced cell death in PC12 cells, whereas 17 alpha-estradiol, nonestrogenic stereoisomer, did not exert any significant protective effect on CT-induced cell death. These results suggest that protective effects of estrogen may be mediated by estrogen receptor (ER) in PC12 cells. To confirm the results, we determined the effects of tamoxifen, an estrogen receptor antagonist. Tamoxifen blocked the protective effects of 17 beta-estradiol, although it did not affect those of 17 alpha-estradiol. Overall, it might be thought that the protective effect of estradiol on CT-induced cell death is achieved by hormonal properties mediated through the estrogen receptor rather than the structural properties as a reducing agent.

Alzheimer Disease↗
PubMed2001

The protective role of HSP90 against 3-hydroxykynurenine-induced neuronal apoptosis.

3-hydroxykynurenine (3HK), an endogenous metabolite of tryptophan in the kynurenine pathway, is a potential neurotoxin in several neurodegenerative disorders. Stabilizing protein structure, heat shock proteins (HSPs) have diverse roles as molecular chaperones to mediate stress tolerance. In the present study, we investigated the possible protective role of HSPs against 3HK induced neuronal cell death. Here we report that 3HK induced in a dose- and time-dependent manner neuronal cell death in neuroblastoma SK-N-SH cells. The cell death showed characteristic apoptotic features such as cell shrinkage, plasma membrane blebbing, chromatin condensation, and nuclear condensation and fragmentation. Furthermore, SK-N-SN cells were protected from 3HK induced cytotoxicity by prior elevation of HSPs expression. Our results show that the protective effect was abolished by HSP90 anti-sense oligonucleotides while not by HSP27 and HSP70 anti-sense oligonucleotides. Also, our result shows that HSP90 effectively inhibits caspases activities leading to the apoptosis. These results suggest that 3HK induces apoptosis in neuroblastoma SK-N-SN cells and that HSP90 is major contributing protein component of protection against 3HK induced apoptosis.

Apoptosis↗
PubMed2001

Acute multifocal placoid pigment epitheliopathy and central nervous system involvement: nine new cases and a review of the literature.

OBJECTIVE: The authors describe nine new cases of acute multifocal placoid pigment epitheliopathy (AMPPE) with associated central nervous system (CNS) involvement and permanent visual sequelae. The study includes a review of the literature and discussion of evaluation, management, and treatment options. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Nine patients were identified with AMPPE and CNS involvement in addition to 22 patients reviewed in the literature. MAIN OUTCOME MEASURES: A review of nine patients with AMPPE and CNS involvement was performed. Charts were reviewed for age, gender, preceding viral prodromes, visual acuity, ophthalmologic examination findings, CNS findings, and treatment. RESULTS: Thirty-one patients (nine new patients) were diagnosed with AMPPE and various degrees of CNS involvement. Ages ranged from 8 to 54 years, with an average of 27 years. Twenty-one males (68%) and 10 females (32%) were identified. Eleven patients (35%) had antecedent viral illnesses. Visual acuity was variable and ranged from 20/20 to count fingers. The spectrum of CNS findings ranged from headaches to sagittal sinus thrombosis. CONCLUSIONS: Acute multifocal placoid pigment epitheliopathy can be associated with CNS abnormalities and permanent visual deficits. Neuroimaging, lumbar puncture, and cerebral angiography analysis provide useful diagnostic tools when CNS involvement is suspected. Intravenous corticosteroids and collaboration with neurovascular colleagues should be considered in these situations. In cases complicated by CNS arteritis, immunosuppressive agents can be a beneficial adjunct to corticosteroids.

Acute Disease↗
PubMed2001

Airbags and bilateral eye injury: five case reports and a review of the literature.

We report five cases of bilateral eye injuries from airbag deployment in motor vehicle crashes and review the world's literature on ocular injuries associated with airbags. The cases in the literature were identified by cross-referencing Medline searches from airbags and ocular injuries. Additional cases were identified after review of references from each article in the search. An additional 89 cases from the literature were identified and are included for discussion. Patients were treated individually in a noncontrolled, nonrandomized fashion according to the nature of each injury with regular follow-up examinations in clinic. Of the 94 cases studied, 24 (27%) were bilateral eye injuries, and 15 (16%) patients were wearing spectacles at the time of the accident. The most common injuries included corneal abrasions, eyelid trauma, and hyphemas. Outcomes ranged from complete resolution of symptoms and return of normal visual acuity to primary enucleation. This report describes the wide spectrum of eye injuries that may occur after airbag deployment. We suggest a management plan for the evaluation and treatment of the ocular complications of airbag-related trauma.

Accidents, Traffic↗
PubMed2001

Complex sclerosing lesion: the lesion is complex, the management is straightforward.

BACKGROUND: Complex sclerosing lesion (CSL) and its smaller counterpart, the radial scar (RS), are frequently seen pathological entities. They are clinically asymptomatic and, prior to the implementation of mammographic screening, were most commonly found incidentally during pathological examination of other biopsied lesions. Complex sclerosing lesions are being detected regularly on mammograms due to widespread screening; many of their features resemble those of malignancy. Management varies and has been controversial. METHODS: Twenty-three cases of CSL detected during the first prevalent round of screening at BreastScreen Western Sydney (from February 1993 until June 1995) are presented and reviewed. Assessment was by a combination of radiological, clinical and cytological work-up prior to surgical biopsy. In addition, 126 spiculated carcinomas detected in the same period were reviewed and compared. RESULTS: Fourteen RS/CSL (62%) had lucent centres and nine (38%) had a central mass; three had been diagnosed provisionally as RS/CSL. Spicule lengths ranged from 25 to 90 mm; central masses ranged from 5 to 50 mm; and mass:spicule length ratio ranged from 1.2:1 to 1:10. Calcification (benign or indeterminate) was present in six cases (29%). No RS/CSL contained 'suspicious' calcifications, whereas 120 of 126 carcinomas (95%) had a central mass and six (5%) had a lucent centre (spicule lengths: 10-90 mm; central mass: 5-40 mm; and mass:spicule length ratio: 1.1:1-1:10). Twenty-one spiculated carcinomas (17%) contained microcalcifications (14 benign or indeterminate; seven suspicious). Provisional radiological diagnosis (PRD) after mammogram, with or without ultrasound, for histologically confirmed RS/CSL, was RS/CSL in 18 cases (78%), carcinoma in four cases (17%) and equivocal in one case (5%). For eight (6.5%) spiculate carcinomas the PRD was RS/CSL prior to histological diagnosis. The RS/CSL were detected with equal frequency in right and left breasts, and 22 (96%) lesions occurred in the upper breast. Seven RS/CSL (31%) and 83 spiculated carcinomas (65%) had been described as 'palpable' but most were subtle. Twelve fine-needle aspiration biopsies were performed (six 'palpable' lesions (no radiological guidance); four with ultrasound guidance and two with stereotactic guidance), and five (62.5%) of eight adequate lesions were reported as benign, two (25%) were reported as atypical, and one (12.5%) was reported as suspicious. CONCLUSIONS: Definitive mammographic and sonographic differentiation of RS/CSL and stellate-type carcinoma is impossible. For screen-detected lesions that may be RS/CSL, the appropriate surgical procedure is a small but adequate biopsy using guidewire or other localization methods with optimal cosmetic incision.

Biopsy, Needle↗
PubMed2001

C-terminal fragment of amyloid precursor protein induces astrocytosis.

One of the pathophysiological features of Alzheimer's disease is astrocytosis around senile plaques. Reactive astrocytes may produce proinflammatory mediators, nitric oxide, and subsequent reactive oxygen intermediates such as peroxynitrites. In the present study, we investigated the possible role of the C-terminal fragment of amyloid precursor protein (CT-APP), which is another constituent of amyloid senile plaque and an abnormal product of APP metabolism, as an inducer of astrocytosis. We report that 100 nM recombinant C-terminal 105 amino acid fragment (CT105) of APP induced astrocytosis morphologically and immunologically. CT105 exposure resulted in activation of mitogen-activated protein kinase (MAPK) pathways as well as transcription factor NF-kappaB. Pretreatment with PD098059 and/or SB203580 decreased nitric oxide (NO) production and nuclear factor-kappa B (NF-kappaB) activation. But inhibitors of NF-kappaB activation did not affect MAPKs activation whereas they abolished NO production and attenuated astrocytosis. Furthermore, conditioned media derived from CT105-treated astrocytes enhanced neurotoxicity and pretreatment with NO and peroxynitrite scavengers attenuated its toxicity. These suggest that CT-APP may participate in Alzheimer's pathogenesis through MAPKs- and NF-kappaB-dependent astrocytosis and iNOS induction.

Amyloid beta-Protein Precursor↗
PubMed2001

Use of a guide device to place pedicle screws in the thoracic spine: a cadaveric study. Technical note.

In this cadaveric study, the safety and accuracy of a specially designed guide device for the placement of thoracic pedicle screws was investigated in a normal anatomical situation. Five embalmed human cadaveric thoracic spines (T1-12) were used for the study of transpedicular screw placement in the thoracic spine. Overall 120 screws were placed at all thoracic levels. The screws were inserted bilaterally in the thoracic pedicles by using a specially designed guide device. No radiographs or other imaging studies were obtained. Following screw placement, computerized tomography scans were performed to evaluate the accuracy of the pedicle screw positioning. Seven (5.8%) of the screws penetrated the pedicle wall or the vertebral body (VB) cortex. Two screws (1.7%) penetrated the medial wall of the pedicle. Two screws (1.7%) penetrated the lateral wall of the pedicle, and one screw (0.8%) penetrated the lateral wall of the pedicle and the anterior VB cortex simultaneously. Two screws (1.7%) penetrated the anterior VB cortex. Compared with the results of other studies, the findings here indicate that using this device to guide the placement of thoracic pedicle screws can significantly reduce the incidence of pedicle penetration, particularly in the medial wall.

Bone Screws↗
PubMed2001

Differential inhibition and inactivation of human CYP1 enzymes by trans-resveratrol: evidence for mechanism-based inactivation of CYP1A2.

trans-Resveratrol (3,5,4'-trihydroxy-trans-stilbene) has been reported to confer chemoprotection against 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenicity in a murine model. A potential mechanism for this effect by trans-resveratrol is inhibition of DMBA-bioactivating cytochrome P450 (CYP) enzymes such as CYP1B1, CYP1A1, and CYP1A2. In the present study, we examined in detail the in vitro inhibitory effects of trans-resveratrol on these three human CYP enzymes. trans-Resveratrol decreased 7-ethoxyresorufin O-dealkylation activity catalyzed by human recombinant CYP1B1, CYP1A1, and CYP1A2 in a concentration-dependent manner and by a mixed type of inhibition. This direct inhibition was enzyme-selective, as judged by the differences in the apparent K(i) values (0.8 +/- 0.1 microM, 1.2 +/- 0.1 microM, and 15.5 +/- 1.1 microM for CYP1B1, CYP1A1, and CYP1A2, respectively). Preincubating recombinant CYP1A2 or human liver microsomes with trans-resveratrol and NADPH prior to the initiation of substrate oxidation resulted in a time- and concentration-dependent decrease in catalytic activity. The inactivation of liver microsomal CYP1A2 by trans-resveratrol required NADPH, was not reversible by dialysis, and was not affected by the trapping agents glutathione, N-acetylcysteine, catalase, or superoxide dismutase, but was attenuated by a CYP1A2 substrate, imipramine. Analysis of a panel of individual human liver microsomes showed intersample differences in the response to the in vitro inactivation by trans-resveratrol. In contrast to CYP1A2, CYP1B1 was not subject to inactivation by this compound and the reduction in CYP1A1 activity was time- but not concentration-dependent. In summary, trans-resveratrol differentially inhibited human CYP1 enzymes and this occurred by two distinct mechanisms: direct inhibition (mainly CYP1B1 and CYP1A1) and mechanism-based inactivation (CYP1A2).

Aryl Hydrocarbon Hydroxylases↗
PubMed2000

Identification of a putative DEAD-box RNA helicase and a zinc-finger protein in Candida albicans by functional complementation of the S. cerevisiae rok1 mutation.

We identified two novel genes, CHR1 and CSR1, of the fungal pathogen Candida albicans, by functional complementation of the Saccharomyces cerevisiae rok1 mutation. The Rok1 protein is a member of the DEAD protein family of ATP-dependent RNA helicases. ROK1 is required for cell cycle progression and also for rRNA processing. The CHR1 gene product of 578 amino acids is highly homologous to the Rok1 protein (54% identity) and is considered to be a putative DEAD-box RNA helicase. We predict that the CSR1 gene encodes a 73 kDa protein of 612 amino acids with five zinc-finger motifs at the C-terminal region. CHR1 or CSR1 on a high-copy number plasmid showed a slow-growth phenotype in a condition where the ROK1 expression is turned on from the GAL1 promoter. This result is consistent with the lethality caused by the ROK1 overexpression. We conclude that CHR1 encodes a functional homologue of Rok1 protein and CSR1 is a heterologous suppressor of the rok1 mutation.

Amino Acid Sequence↗
PubMed2000

Trans-resveratrol modulates the catalytic activity and mRNA expression of the procarcinogen-activating human cytochrome P450 1B1.

The present study was performed to determine if trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene) modulates the catalytic activity and gene expression of cytochrome P450 1B1 (CYP1B1). In vitro, trans-resveratrol decreased human recombinant CYP1B1-catalyzed 7-ethoxyresorufin O-dealkylation activity, with an IC50 value of 1.4 +/- 0.2 microM (mean +/- SEM). Enzyme kinetic analysis indicated that trans-resveratrol inhibited CYP1B1 enzyme activity by a mixed-type inhibition and the apparent Ki was 0.75 +/- 0.06 microM. To determine if trans-resveratrol modulates constitutive CYP1B1 gene expression, cultured MCF-7 human breast carcinoma cells were treated with trans-resveratrol. As indicated by RT-PCR analysis, treatment of MCF-7 cells with 10 microM trans-resveratrol decreased relative CYP1B1 mRNA levels after 5 h, but not after 1.5 or 3 h, of exposure. trans-Resveratrol treatment at 5, 7.5, 10, or 20 microM for 5 h produced a concentration-dependent decrease in CYP1B1 mRNA levels. The extent of suppression was approximately 50% at 20 microM concentration. The suppressive effect was not a consequence of a toxic response to the compound as assessed by a cell proliferation assay. Overall, our novel finding that trans-resveratrol inhibits the catalytic activity and suppresses the constitutive gene expression of CYP1B1 leads to the possibility that this nutraceutical confers protection against toxicity and carcinogenicity induced by compounds that undergo CYP1B1-catalyzed bioactivation.

Anticarcinogenic Agents↗
PubMed2000

Creating world-class supply chains.

This article will share knowledge in two areas: The elements of world-class supply chains and the linking processes from customers' customers to suppliers' suppliers and the management approaches needed to engage the people and the organization in an effective implementation process to achieve world-class status.

Commerce↗
PubMed1999

Optic nerve edema as a consequence of respiratory disease.

The authors describe a patient with bilateral papilledema, visual field abnormalities, poorly reactive pupils, meningeal enhancement on cranial MRI, and diffuse brain parenchymal hypervascularity. The opening pressure at the time of lumbar puncture was normal, and results of other CSF studies were normal. All abnormalities resolved with home oxygen therapy.

Diagnosis, Differential↗
PubMed1999

Emperipolesis of erythroblasts within Kupffer cells during hepatic hemopoiesis in human fetus.

The state in which cells can inhabit other cells without damage is known as emperipolesis. Emperipolesis has been found in various physiological and pathological conditions. We performed a study of emperipolesis of erythroblasts within Kupffer cells in the human fetal liver. We found that Kupffer cells, identified by CD68 immunolabeling, contained 4-8 erythroblasts in a hypertrophic cytoplasm on light microscopy. Emperipoletic erythroblasts were present in various maturation stages from proerythroblast to reticulocyte. By electron microscopy, we found that erythroblasts occupied membrane-bound vacuoles that were separated from each other by thin partitions of Kupffer cell cytoplasm. Neither emperipoletic erythroblasts nor their Kupffer cell hosts showed evidence of damage. Emperipoletic cells in mitosis were found, which suggests the capacity for the proliferation of erythroblasts within Kupffer cells. Some Kupffer cells were seen to contain both emperipoletic cells and phagosomes, without evidence of interaction. Erythroblasts and other hemopoietic cells were also found to be closely associated with the sinusoidal surface of Kupffer cells. However, intercellular junctions, if present, were inconspicuous. On occasion, Kupffer cells engorged with erythroblasts nearly occluded the sinusoidal lumen. Our results demonstrate that emperipolesis of erythroblasts within Kupffer cells occurs in human fetal hepatic hemopoiesis. We suggest that emperipolesis may be one of the mechanisms that support the maturation of erythroblasts in the fetal liver.

Antigens, CD↗
PubMed1999

Ophthalmoplegic migraine with unusual features.

We report the details of a patient with an unusual form of ophthalmoplegic migraine resulting in permanent vertical misalignment of the affected eye. The presentation, history, and ophthalmologic examination are reported as well as disease course and follow-up complications. We review the literature on ophthalmoplegic migraine with discussion regarding typical presentation, methods of diagnosis, and other diseases which may cause diagnostic confusion. In light of current case reports on ophthalmoplegic migraine, this is the first documented example with a permanent deficit.

Adult↗
PubMed1998

Characterization and intracellular localization of the Rok1 protein involved in yeast cell division.

The ROK1 gene is essential for the cell cycle progression in Saccharomyces cerevisiae. ROK1 has been predicted to encode an ATP-dependent RNA helicase of the DEAD-box family. We have analyzed the ROK1 gene expression both at the protein and RNA levels. Polyclonal antibodies were raised against trpE::rok1 hybrid proteins and were affinity purified by using lacZ::rok1 hybrid proteins. Western blot experiments using anti-Rok1 antibodies revealed a single protein band of 64 kDa which is an expected size from the Rok1 amino acid sequence. Indirect immuno-fluorescence showed that the Rok1 protein is localized predominantly to the cytoplasm of the vegetatively growing cells. We have detected immunocross-reactive homologs of Rok1p in Candida albicans and Drosophila melanogaster.

Animals↗
PubMed1998

Microangiopathy of the brain, retina, and cochlea (Susac syndrome). A report of five cases and a review of the literature.

OBJECTIVE: This study reports five new cases of microangiopathy of the brain, retina, and cochlea (Susac syndrome) and reviews the world's literature. DESIGN: Five cases were systematically studied by the authors. The cases in the literature were identified through Medline searches for Susac syndrome; microangiopathy of the brain, retina, or ear; and cross-referencing the indexes of each retrieved article. PARTICIPANTS: The number of new patients studied in this report was five. An additional 41 patients were culled from the literature. INTERVENTION: Patients were treated with corticosteroids, antineoplastic agents, and other methods in a noncontrolled, nonrandomized fashion. MAIN OUTCOME MEASURES: With respect to therapeutic intervention, the main clinical outcome measures were return of vision, improvement of neurologic and psychiatric manifestations, and recovery of auditory function. Alterations of abnormalities observed by cranial magnetic resonance imaging also were monitored. RESULTS: Of 46 identified patients, 39 were women. The mean age of the patients was 30 years. Forty-one patients (89%) had arterial occlusions, which were bilateral in 60%. Thirty-one patients (67%) reported hearing loss. Twenty patients (44%) had a global encephalopathy, but other neurologic manifestations were common. The mean duration of the illness was 46.7 months. CONCLUSION: This rare syndrome is more common than previously thought, has a strong female preponderance, and often can be identified at an early stage with a careful history and physical examination. Magnetic resonance imaging of the brain often shows lesions suggestive of multiple sclerosis. Fluorescein angiography may show arteriolar wall hyperfluorescence. Early treatment with corticosteroids often is, although not invariably, associated with a good prognosis. The disease appears to be self-limited in most patients.

Adult↗