Search PubMed⌕ Search

Biomedical subjects

D H Lee

Publications and source records attributed to D H Lee.

At least 163 records · Page 9Linked to original sources
PubMed1999

Meningioangiomatosis. A comprehensive analysis of clinical and laboratory features.

Meningioangiomatosis (MA) is a rare, benign, focal lesion of the leptomeninges and underlying cerebral cortex characterized by leptomeningeal and meningovascular proliferation. It may occur sporadically or in association with neurofibromatosis type 2. Previous reports have emphasized histological and imaging features. Data on the management of these patients are sparse, and electrophysiological features of MA lesions have not been published. We assessed the clinical, electrophysiological, histopathological and imaging features as well as the surgical outcome in MA, and compared MA with and without neurofibromatosis. Seven patients with MA at our centre were investigated and their outcome was assessed. A review of the literature is included. MA exhibits a wide range of clinical, imaging, histopathological and electrophysiological features, making the diagnosis difficult. Sporadic MA cases are not associated with neurofibromatosis and the two disorders are genetically distinct. Medically refractory, localization-related epilepsy is the commonest presentation in sporadic cases, but atypical presentations also occur. Unlike sporadic cases, MA with neurofibromatosis is often found incidentally, does not produce seizures, occurs less frequently (ratio of 1:4), and is multifocal. MRI findings in MA correspond to the histological picture. However, the appearance on imaging is non-specific and may suggest cystic atrophy, angioma and tumours. Several abnormalities have been found in close proximity to MA lesions, i.e. meningioma, oligodendroglioma, arteriovenous malformation, encephalocoel and orbital erosion. In spite of histopathological diversity, MA lesions are either predominantly cellular or vascular. Immunohistochemical results are inconsistent among cases, add little to the diagnosis, and do not support a meningeal origin. Electrocorticographic recordings from the surface and within MA lesions revealed a spectrum of electrophysiological expressions. Intrinsic epileptogenicity of MA lesions was documented in some cases. Epileptogenicity was confined to the perilesional cortex in some patients and it was complex (extralesional, multifocal, generalized) in others. Only 43% of our patients became seizure-free postoperatively compared with 68% previously reported, and >70% of our patients and those in the literature continued to require antiepileptic drugs. This is in keeping with the diverse electrophysiology of MA and suggests a less optimistic postoperative outcome than previously recognized.

Adolescent↗
PubMed1999

Prognosis of gastrointestinal smooth-muscle (stromal) tumors: dependence on anatomic site.

Although the significance of various prognostic factors, such as tumor size and mitotic index (MI), has been well established for smooth-muscle tumors of the stomach, the significance of these factors in other sites is less well defined. We studied 1004 patients with gastrointestinal smooth-muscle tumors for whom vital status could be determined. The average MI and tumor size varied significantly among the five major sites examined: esophagus (53 cases), stomach (524 cases), small bowel 252 cases), colon/rectum (108 cases), and omentum/mesentery/peritoneum (67 cases). There was a significant difference in site-specific survival (p = 0.001), with 10-year survival varying between 50% and 70%. Multivariate analysis demonstrated tumor location (p = 0.0320), size (p = 0.0003), MI (p < 0.0001), and patient age (p < 0.0001) to each carry independent prognostic value. The significance of MI was highly site dependent. Separation of survival curves for the stomach, using a threshold for analysis of either 5 or 10 mitotic figures/50 high-power fields, was very good. In contrast, small-bowel tumors showed little separation between survival curves, regardless of whether a threshold of 1, 5, or 10 mitotic figures MF/50 high-power fields was used to distinguish groups. In no site were tumor size and MI alone sufficient to provide an accurate long-term prediction of prognosis. Although tumor location, size, MI, and age have independent value in predicting the prognosis of patients with gastrointestinal smooth-muscle tumors, better methods are still required to accurately predict clinical course.

Adolescent↗
PubMed1999

Infratentorial subdural empyema, pituitary abscess, and septic cavernous sinus thrombophlebitis secondary to paranasal sinusitis: case report.

OBJECTIVE AND IMPORTANCE: Infratentorial empyema, pituitary abscess, and septic cavernous sinus thrombophlebitis are all rare and potentially lethal conditions. The occurrence of all three in a single patient has not previously been described. We present such a case occurring in a young, otherwise healthy man. CLINICAL PRESENTATION: A 26-year-old man with a remote history of sinusitis developed rapidly progressive headache, fever, right eye pain, swelling, proptosis, and visual impairment. Magnetic resonance imaging demonstrated diffuse pansinusitis, including sphenoid sinusitis, and extension of inflammation and infection into the adjacent cavernous sinuses, pituitary gland, and posterior fossa. INTERVENTION: Urgent drainage of the ethmoid and maxillary sinuses was performed; pus was not identified. The patient continued to deteriorate clinically with worsening of visual acuity. Computed tomography of the head performed the next day revealed worsening hydrocephalus and an enlarging posterior fossa subdural empyema. Urgent ventricular drainage and evacuation of the empyema was performed, and subsequently, the patient's clinical course improved. The microbiology results revealed alpha hemolytic streptococcus and coagulase-negative staphylococcus species. The patient survived but during the follow-up period had a blind right eye and pituitary insufficiency. CONCLUSION: Paranasal sinusitis can have devastating intracranial sequelae. Involvement of the adjacent pituitary gland and cavernous sinuses can result in serious neurological morbidity or mortality, and retrograde spread of infection through the basal venous system can result in subdural or parenchymal brain involvement. A high index of suspicion and aggressive medical and surgical treatment are crucial for patient survival, but the morbidity rate remains high. Our patient survived but lost anterior pituitary function and vision in his right eye.

Abscess↗
PubMed1999

Amycolatopsis thermoflava sp. nov., a novel soil actinomycete from Hainan Island, China.

A soil isolate, which had been assigned to the genus Nocardia, was shown to have properties consistent with its classification in the genus Amycolatopsis. An almost complete nucleotide sequence of the 16S rDNA of the strain was determined following cloning and sequencing of the amplified gene. The sequence was aligned with those available for members of the family Pseudonocardiaceae and related taxa and phylogenetic trees were inferred using three tree-making algorithms. The organism consistently formed a distinct monophyletic clade with the type strain of Amycolatopsis methanolica, but DNA-DNA relatedness data showed that the two strains belonged to distinct genomic species. The organism was also distinguished from the type strains of all validly described species of Amycolatopsis using a battery of phenotypic properties. The genotypic and phenotypic data show that the strain merits recognition as a new species of the genus Amycolatopsis. The name proposed for the new species is Amycolatopsis thermoflava sp. nov. The type strain is IFO 14333T.

Actinomycetales↗
PubMed1999

Receptor subtype mediating the adrenergic sensitivity of pain behavior and ectopic discharges in neuropathic Lewis rats.

Receptor subtype mediating the adrenergic sensitivity of pain behavior and ectopic discharges in neuropathic Lewis rats. We attempted to identify the subtype of alpha-adrenergic receptor (alpha-AR) that is responsible for the sympathetic (adrenergic) dependency of neuropathic pain in the segmental spinal injury (SSI) model in the Lewis strain of rat. This model was chosen because our previous study showed that pain behaviors in this condition are particularly sensitive to systemic injection of phentolamine (PTL), a general alpha-AR blocker. We examined the effects of specific alpha1- and alpha2-AR blockers on 1) behavioral signs of mechanical allodynia, 2) ectopic discharges recorded in the in vivo condition, and 3) ectopic discharges recorded in an in vitro setup. One week after tight ligation of the L5 and L6 spinal nerves, mechanical thresholds of the paw for foot withdrawals were drastically lowered; we interpreted this change as a sign of mechanical allodynia. Signs of mechanical allodynia were significantly relieved by a systemic injection of PTL (a mixed alpha1- and alpha2-AR antagonist) or terazosin (TRZ, an alpha1-AR antagonist) but not by various alpha2-AR antagonists (idazoxan, rauwolscine, or yohimbine), suggesting that the alpha1-AR is in part the mediator of the signs of mechanical allodynia. Ongoing ectopic discharges were recorded from injured afferents in fascicles of the L5 dorsal root of the neuropathic rat with an in vivo recording setup. Ongoing discharge rate was significantly reduced after intraperitoneal injection of PTL or TRZ but not by idazoxan. In addition, by using an in vitro recording setup, spontaneous activity was recorded from teased dorsal root fibers in a segment in which the spinal nerve was previously ligated. Application of epinephrine to the perfusion bath enhanced ongoing discharges. This evoked activity was blocked by pretreatment with TRZ but not with idazoxan. This study demonstrated that both behavioral signs of mechanical allodynia and ectopic discharges of injured afferents in the Lewis neuropathic rat are in part mediated by mechanisms involving alpha1-ARs. These results suggest that the sympathetic dependency of neuropathic pain in the Lewis strain of the rat is mediated by the alpha1 subtype of AR.

Adrenergic alpha-Agonists↗
PubMed1999

Molecular analysis of a tryptophan-2-monooxygenase gene (IaaM) of Agrobacterium vitis.

Tryptophan-2-monooxygenase genes occur in a number of bacteria and encode the conversion of tryptophan to the plant hormone precursor indole-3-acetamide. The role of these genes in the plant-bacteria interaction is often unclear. However, their function as a virulence determinant is established for Pseudomonas savastanoi and Agrobacterium tumefaciens. Some members of the Agrobacteria, such as Agrobacterium vitis have a limited host range. We have characterized the tryptophan-2-monooxygenase (iaaM) gene of A. vitis strain AG162 and show it is different from other A. vitis strains and related to iaaM of A. rhizogenes. The sequence of AG162 iaaM was deposited in the Genbank database under the accession number AF142716.

Amino Acid Sequence↗
PubMed1999

Axenic cultivation and characterization of Giardia lamblia isolated from humans in Korea.

Inoculating of human fecal cysts to suckling Mongolian gerbils, two Giardia lamblia isolates, K1 and K2, were established as axenic cultures. Using this in vitro culture, both isolates were characterized as a "medium-rate grower" upon its growth pattern. These two Giardia isolates were grouped by using two genetic analysis. With genetic analysis of SSU-rDNA sequences, both K1 and K2 were found as members of Hopkins' group 1, despite some nucleotide differences noticed in K2 (5 differences/292 bases). The other genetic study used PCR-RFLP of the tim (triose phosphate isomerase) gene. Both of K1 and K2 were found to belong to Nash's group 2. Our results suggest that Nash's group 2 can not be a separate group, but a part of Hopkins' group 1.

Animals↗
PubMed1999

The loss of expression of transforming growth factor-beta receptors correlates with the histopathologic tumor grade in bladder transitional cell carcinoma patients.

Transforming growth factor-beta (TGF-beta), a pleiotropic growth factor, is a potent inhibitor of cellular proliferation in cells of epithelial origin. Recently, it has been suggested that a loss of sensitivity to TGF-beta through a loss of expression of TGF-beta receptors T beta R-I and T beta R-II--is associated with tumor initiation and progression. Therefore, to investigate the relationship between TGF-beta receptors expression and carcinogenesis of bladder TCC, this study examined the expression of T beta R-I and T beta R-II in 46 bladder TCC patients using immunohistochemistry. Since histopathological grade is a widely accepted marker of prognosis, the results were compared in relation to the three grades of bladder TCC. The results demonstrated that the loss of TGF-beta receptors expression is associated with increasing histopathological grades of bladder TCC. Specifically, both T beta R-I and T beta R-II were readily detected in all 10 normal bladder mucosa specimens. Likewise, all 6 specimens of grade I TCC samples expressed high levels of both TGF-beta receptors. However, among grade II TCC samples, T beta R-I and T beta R-II were detected in 78% and 89%, respectively: among grade III TCC samples, T beta R-I and T beta R-II were detected in 45% and 41%, respectively. These results suggested that loss of sensitivity to TGF-beta may play a role in the progression of TCC from low to high grade disease.

Adult↗
PubMed1999

Identification of IgE-reacting Clonorchis sinensis antigens.

Clonorchis sinensis is a liver fluke and it is the most prevalent human parasite in Korea at present. The parasite infection induces immune responses, characteristically an increased production of parasite-specific IgE in the host. Major IgE-reacting C. sinensis antigens in infected humans have been protein bands with MWs of 15, 28, 37, 45, 51, 56, 62, 66, 74, 97 and 160 KD identified by immunoblot analysis. Individual variations of the IgE binding pattern to C. sinensis antigens have also been documented. Using immune BALB/c mouse sera, IgE-reacting protein bands have been visualized with MWs of 28, 74, 86, 160 and several > 200 KD. One of the most strongly reacted C. sinensis antigenic proteins with a molecular weight of 28 KD was purified by gel filtration and preparative electrophoresis. Using a monoclonal antibody produced against the antigenic protein, the protein was localized in the parasite's intestine, and also found to be contained in excretory-secretory antigens.

Animals↗
PubMed1999

The role of radiotherapy in the treatment of aggressive fibromatosis.

Aggressive fibromatosis is a rare benign soft tissue tumor that is difficult to cure because of its infiltrative nature and high tendency to recur locally. The authors retrospectively analyzed 20 patients with histologically-confirmed fibromatosis. All patients underwent surgery with a wide or marginal margin. Five (25%) cases with histologically-negative margins had recurred. External beam radiotherapy was administered to patients whose margins were positive or who had local recurrence. However, out of concern for safety, radiotherapy was not given to two babies and a reproductive-aged woman. The average dose was 5,020 cGy. During the follow-up (mean 32.6 months), all the patients undergoing radiotherapy showed no evidence of local recurrence. A wide local excision has traditionally been the treatment of choice. However, postoperative radiotherapy could be an effective measure for preventing local recurrence in patients with a histologically-positive surgical margin and recurrence independent of any signs of relapse.

Adolescent↗
PubMed1999

Gastric malignant stromal tumor with long stalk impacted into duodenum.

Most GIST have traditionally been classified as submucosal origin by upper gastrointestinal series (UGIS) or endoscopy. However, we experienced a gastrointestinal mesenchymal origin tumor expressed by polypoid mass with a long stalk. The gastric outlet was obstructed by the polypoid mass on the duodenum. The microscopic findings of the resected mass showed a stromal cell component by immunohistochemical stain. We experienced gastric stromal tumor found as a polypoid mass with long stalk which was easily detected by endoscopy. It would not have been suspected as a stromal tumor as a result of endoscopic findings only.

Aged↗
PubMed1999

Preclinical evaluation of prototype products.

Preclinical evaluation of medical devices (prototype products) offers the opportunity to investigate and study the intended use of device materials. Preclinical evaluation programs are designed to determine the efficacy, safety, and biocompatibility of biomaterials, prostheses, and medical devices. The purpose of safety testing is to determine if a material presents potential harm to the human; it evaluates the interaction of the material with the in vivo environment and determines the effect of the host on the implant. Preclinical evaluation is the determination of the ability of the prototype product to perform with appropriate host response in a specific application, considered from the perspective of human clinical use. Therefore, preclinical data should include materials science and engineering, biology, biochemistry, medicine, host reactions and their evaluation, the testing of biomaterials, and the degradation of materials in a biological environment.

Animals↗
PubMed1999

Tepoxalin enhances the activity of an antioxidant, pyrrolidine dithiocarbamate, in attenuating tumor necrosis factor alpha-induced apoptosis in WEHI 164 cells.

The nuclear transcription factor-kappaB (NF-kappaB) and free radicals are known to be involved in apoptosis. We studied the effects of a series of di-aryl-substituted pyrazole NF-kappaB inhibitors including tepoxalin on tumor necrosis factor alpha (TNFalpha)-induced apoptosis in murine fibrosarcoma WEHI 164 cells. We found that potent inhibitors of NF-kappaB were also effective in attenuating apoptosis. WEHI 164 cells that had been dually treated with tepoxalin and the antioxidant pyrrolidine dithiocarbamate (PDTC) were significantly protected from TNFalpha-induced killing. To study the role of free radicals in mediating TNFalpha-induced apoptosis, stable WEHI 164 cells overexpressing Bcl-2, an antioxidant protein, were generated. These cells were protected from TNFalpha-induced apoptosis and neither tepoxalin nor PDTC provided further significant protection. These results suggest that Bcl-2, PDTC, and tepoxalin may attenuate apoptosis in this system by affecting the same signaling pathway or converging pathways. Because tepoxalin suppresses the release of free radicals, PDTC scavenges free radicals and Bcl-2 is an antioxidant protein, free radicals are among the key mediators of this TNF-induced killing event. Tepoxalin and antioxidants may be useful in developing new therapeutics for treating neurodegenerative diseases, autoimmune deficiency syndrome, and ischemia-reperfusion injuries.

Animals↗
PubMed1999

Inhibition of activation of nuclear factor kappaB is responsible for inhibition of inducible nitric oxide synthase expression by higenamine, an active component of aconite root.

Effects of higenamine on nitric oxide (NO) production and inducible NO synthase (iNOS) mRNA expression (RAW 264.7 cells), on vascular reactivity in vitro and in vivo (rats), and on survival rates (mice) and serum nitrite/nitrate levels (rats) were investigated by using last lipopolysaccharide (LPS) plus interferon (IFN)-gamma. Higenamine concentration-dependently inhibited NO production and inducible NO synthase mRNA in RAW 264.7 cells, in which the IC(50) was 53 microM. Higenamine (10 mg/kg i.p.) administered 90 min before LPS (5 mg/kg i.v.) prevented not only LPS-induced hypotension but also pressor response to norepinephrine (1 microgram/kg) in rats. Incubation of thoracic aorta with LPS (300 ng/ml) for 8 h in vitro resulted in suppression of the vasoconstrictor effects to phenylephrine, which was prevented by coincubation with higenamine. The survival rate to endotoxin in mice was significantly (P <.01) increased by the presence of higenamine in the LPS-treated group up to 48 h. Serum nitrite/nitrate levels were significantly (P <.05) reduced by higenamine in LPS-treated rats. Finally, higenamine inhibited the activation of nuclear factor kappaB in RAW 264.7 cells due to LPS + IFN-gamma by mobility shift assays. Taken together, these data strongly suggest that higenamine inhibits iNOS expression by inhibiting nuclear factor kappaB activation by LPS + IFN-gamma, which may be beneficial in inflammatory diseases in which enhanced formation of NO is the main causative factor. Furthermore, due to positive inotropic action, higenamine may be more effective in a condition where myocardial contractility is likely to depress, such as in septic shock and/or endotoxin-induced inflammatory disorders.

Aconitum↗
PubMed1999

Decreased expression of transforming growth factor beta receptor type I is associated with poor prognosis in bladder transitional cell carcinoma patients.

Transforming growth factor (TGF) beta, a potent growth inhibitor of proliferation in most cells, usually exerts its effects through an interaction with membrane receptors, type I (TbetaR-I) and type II (TbetaR-II). In the present study, the expression of TGF-beta receptors was correlated with tumor grade, pathological stage, and probability of progression and survival in patients with bladder transitional cell carcinoma (TCC). To this end, immunohistochemistry was carried out in specimens obtained from 59 patients who underwent either radical cystectomy or transurethral resection of bladder tumor. Among these patients, 18 (30.5 %) had loss of TbetaR-I expression, whereas 27 (44.0%) had loss of TbetaR-II expression. There was a correlation between the loss of expression of TbetaR-I and TbetaR-II and the tumor grade (P = 0.041 and P = 0.026, respectively). In addition, both pathological and lymph node status also were associated with the loss of TbetaR-I and TbetaR-II expression (P = 0.025 and P = 0.004, respectively). Interestingly though, only the loss of expression of TbetaR-I was associated with an increased probability of tumor progression and a decreased probability of survival (P = 0.0046 and P = 0.0022, respectively). These results suggest that the status of TbetaR-I expression may be a potential prognostic marker in patients with bladder TCC.

Activin Receptors, Type I↗
PubMed1998

Differential accumulation of transcripts for ACC synthase and ACC oxidase homologs in etiolated mung bean hypocotyls in response to various stimuli.

Ethylene can be produced by a variety of developmental and environmental factors such as ripening, the plant hormone auxin, and mechanical wounding via a biosynthetic pathway including AdoMet synthase, ACC synthase, and ACC oxidase steps. ACC synthase and ACC oxidase are known to be encoded by multigene families, and are believed to be differentially expressed in response to various stimuli. In mung bean, ACC synthase is encoded by 7 genes, ACS1, ACS2 ACS3, ACS4, ACS5, ACS6, and ACS7, and ACC oxidase by 2 genes, ACO1 and ACO2. In this study, was have investigated differential accumulation of transcripts for ACC synthase and ACC oxidase homologs in etiolated mung bean hypocotyls under various conditions by the semiquantitative RT-PCR method. Primers which can specifically bind and amplify each cDNAs of ACS1, ACS2, ACS3, ACS4, ACS5, ACS6, ACS7, and ACO1, and ACO2 were designed and used to monitor the responses to various stimuli. Transcripts of ACO1 and ACO2 were accumulated constitutively in the hypocotyl segments even without andy treatment. After cold treatment on intact plant, transcripts of ACS5, ACS6, and ACS7 were accumulated in the hypocotyl segments. We also found the excision of hypocotyl segments and incubation in a buffer solution, a typical way of chemical treatments to hypocotyl segments, lowered the level of ACO2 transcripts with little change of the level of ACO1 transcripts. In response to incubation with IAA (0.1 mM) of excised hypocotyl segments, transcripts of ACS1, ACS6, and ACS7 were accumulated and the level of ACO2 transcripts was increased. Transcripts of ACS1, ACS2, ACS3, ACS5, ACS6 and ACS7 were induced by incubation with OGA (50 micrograms/ml), while the transcripts of ACS4 were accumulated and the level of ACO2 transcripts was increased by incubation with 1 mM LiCl. Our results strongly suggest that all seven ACC synthase genes and two ACC oxidase genes must be active and each gene is differentially regulated by a different subset of the inducing factors.

Adjuvants, Immunologic↗