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Biomedical subjects

H M Lee

Publications and source records attributed to H M Lee.

At least 91 records · Page 5Linked to original sources
PubMed2000

Prostate cancer gene therapy: comparison of adenovirus-mediated expression of interleukin 12 with interleukin 12 plus B7-1 for in situ gene therapy and gene-modified, cell-based vaccines.

We have documented previously that adenovirus-mediated interleukin 12 (IL-12) gene therapy is effective for orthotopic tumor control and suppression of pre-established metastases in a preclinical prostate cancer model (Y. Nasu et al., Gene Ther., 6: 338-349, 1999). In this report, we directly compare the effectiveness of an adenovirus that expresses both IL-12 and the costimulatory molecule B7-1 (AdmIL12/B7) with one that expresses IL-12 alone (AdmIL-12) using the poorly immunogenic RM-9 orthotopic murine model of prostate cancer. We document AdmIL-12/B7-mediated secretion of IL-12 and increased surface expression of B7-1 in infected RM-9 tumor cells. A significant reduction in orthotopic tumor size and increased survival was demonstrated in mice treated with a single orthotopic injection of AdmIL-12/B7 compared with AdmIL-12 or controls. Six of 19 animals treated with AdmIL-12/B7 survived long term with apparent eradication of the primary tumor in contrast to one of 38 animals in the AdmIL-12-treated group. Orthotopic treatment of tumors with both vectors led to an infiltration of both CD4+ and CD8+ immunoreactive cells, with AdmIL-12/B7 treatment having a more prolonged infiltration of CD8+ cells. AdmIL-12/B7 was also more effective than AdmIL-12 or controls at suppression of pre-established metastases. We further developed a vaccine model based on s.c. injection of infected, irradiated RM-9 cells and found that both AdmIL-12 and AdmIL-12/B7 are effective at suppressing the development and growth of challenge orthotopic tumors using this protocol.

Adenoviridae↗
PubMed2000

Ridge preservation of dentition with severe periodontitis.

Severe loss of alveolar bone height and width can occur following the removal of teeth with advanced periodontitis. This compromise of the alveolar bone can limit the options available for achieving an acceptable dental restoration. Two case reports are presented of alveolar ridge augmentation after tooth removal and before implant placement using bone grafting and a biodegradable membrane. The resultant alveolar ridges in both patients were adequate for the placement of dental implants.

Adult↗
PubMed1999

Hypoxia-induced mitochondrial and nuclear DNA damage in the rat brain.

In humans, cerebral hypoxia is a common component of severe brain insults, including trauma, stroke, and perinatal asphyxia. Oxidative stress and free radicals incidental to cerebral hypoxia are implicated in damaging macromolecules, leading to collapse of cellular homeostasis and cell death. Neuronal DNA damage, as a direct measurable event, has not been addressed in cerebral hypoxia. Here, we measured hypoxia-induced damage and repair in nuclear and mitochondrial DNA in rat hippocampus and cortex. Two highly sensitive quantitative polymerase chain reaction (QPCR) assays were used to measure DNA damage. One assay measures the integrity of the entire mitochondrial genome and the other the integrity of nuclear DNA. The latter is a novel assay, developed in our laboratory, which utilizes the high copy number of short interspersed DNA elements (SINEs) residing in introns and untranslated regions of mammalian genes. A unique feature of the SINE-mediated QPCR is its ability to amplify simultaneously long random segments of DNA. Consequently, the SINE assay offers sufficient sensitivity for detecting DNA damage at levels that are compatible with the cellular capacity for DNA repair, and are likely to be consistent with cellular survival and therefore adequate for studying the DNA damage response in the brain. In rats, we found that exposure to an atmosphere of 4% oxygen for 30 min resulted in induction of DNA damage in nuclear and to a greater extent, in mitochondrial DNA. Following a 3-hr recovery period in ambient air, dissimilar repair kinetics for nuclear and mitochondrial DNA were measured.

Animals↗
PubMed1999

Prohormone convertase-1 is essential for conversion of chromogranin A to pancreastatin.

The purpose of this study was to test the hypothesis that the endoprotease, prohormone convertase-1 (PC-1), is involved in the processing of the precursor protein chromogranin A (CGA) to a smaller peptide called pancreastatin (PST). A human pancreatic carcinoid cell line (BON) that expresses PC-1, CGA and PST was stably transfected with antisense PC-1 mRNA. BON cells expressing antisense PC-1 mRNA showed nearly complete abolishment of PC-1 protein (approximately 95% reduction) and an 80% reduction in cell content of PST immunoreactivity (PST-IR) as assessed by high-performance liquid chromatography in combination with measurement of PST-IR. These findings indicate that PC-1 is essential for processing CGA to PST.

Aspartic Acid Endopeptidases↗
PubMed1999

On-line trace enrichment for the simultaneous determination of microcystins in aqueous samples using high-performance liquid chromatography with diode-array detection.

The need for a rapid, sensitive and reliable analytical method for cyanobacterial toxins, microcystins, has been emphasized by the awareness of toxic cyanobacteria as a human-health risk through drinking water. A new high-performance liquid chromatographic method with column switching was developed for the determination of microcystin-LR, -RR and -YR from water samples without pre-purification. The filtered water sample was passed through a Zorbax CN precolumn at a flow-rate of 3 ml/min for on-line trace enrichment. After valve switching, concentrated analytes were eluted in back-flush mode and separated on a Luna C18 column with a gradient of acetonitrile -20 mM phosphate buffer (pH 2.5). The method showed excellent precision, accuracy and speed with detection limits of 0.02 microgram/ml from 100 ml of surface water. The total analysis time per sample was about 90 min. This method improves reliability, sensitivity and sample throughput, and shortens the analysis time compared to analysis methods using off-line solid-phase extraction.

Chromatography, High Pressure Liquid↗
PubMed1999

A chemically modified nonantimicrobial tetracycline (CMT-8) inhibits gingival matrix metalloproteinases, periodontal breakdown, and extra-oral bone loss in ovariectomized rats.

Estrogen deficiency in the postmenopausal (PM) female is the major cause of osteoporosis and may contribute to increased periodontal disease, including alveolar bone loss, seen in these women. In the current study, an animal model of PM osteoporosis, the OVX adult female rat, was studied to determine: (i) the relationship between periodontal breakdown and skeletal bone loss, and (ii) the effect of CMT-8 on gingival collagenase and bone loss. OVX rats were daily gavaged with CMT-8 (1, 2, or 5 mg/rat) for 28 or 90 days; non-OVX rats and those gavaged with vehicle alone served as controls. Elevated collagenase activity, assessed using [3H-methyl] collagen as substrate in the presence or absence of APMA, was seen in the gingiva of the OVX rats, and CMT-8 therapy suppressed this effect. Western blot revealed a similar pattern for MMP-8 and MMP-13 concentrations. The changes in the gingival collagenase activity paralleled changes in periodontal bone loss, which, in turn, reflected trabecular bone density changes. Preliminary studies on PM humans administered sub-antimicrobial tetracycline as a matrix metalloproteinase inhibitor are under way.

Alveolar Bone Loss↗
PubMed1999

IL-4 induces mucin gene expression and goblet cell metaplasia in vitro and in vivo.

Goblet cell metaplasia and mucus hypersecretion are important features in the pathogenesis of asthma. The cytokine IL-4 has been shown to play a role in animal models of asthma, where it induces Th2 lymphocyte differentiation and B lymphocyte IgE class switch. IL-4 has also been implicated in the differentiation of goblet cells via effects on lymphocytes and eosinophils. In this study we hypothesized that IL-4 induces airway epithelial cell mucin gene expression and mucous glycoconjugate production by direct action on these cells. In vitro, cultured airway epithelial cells (NCI-H292) expressed IL-4R constitutively, and IL-4 (10 ng/ml) induced MUC2 gene expression and mucous glycoconjugate production. In vivo, mouse airway epithelial cells expressed IL-4R constitutively, and IL-4 (250 ng) increased MUC5 gene expression and Alcian blue/periodic acid-Schiff-positive staining at 24 h; IL-4 did not increase inflammatory cell numbers in airway tissue or in bronchoalveolar lavage. TNF-alpha and IL-1beta levels in bronchoalveolar lavage were not increased in response to IL-4 instillation. These results indicate that airway epithelial cells express IL-4R constitutively and that IL-4 directly induces the differentiation of epithelium into mucous glycoconjugate-containing goblet cells.

Animals↗
PubMed1999

Microbore high-performance liquid chromatographic determination of cisapride in rat serum samples using column switching.

For the determination of cisapride from serum samples, an automated microbore high-performance liquid chromatographic method with column switching has been developed. After serum samples (100 microl) were directly injected onto a Capcell Pak MF Ph-1 pre-column (10 x 4 mm I.D.), the deproteinization and concentration were carried out by acetonitrile-phosphate buffer (20 mM, pH 7.0) (2:8, v/v) at valve position A. At 2.6 min, the valve was switched to position B and the concentrated analytes were transferred from MF Ph-1 pre-column to a C18 intermediate column (35x2 mm I.D.) using washing solvent. By valve switching to position A at 4.3 min, the analytes were separated on a Capcell Pak C18 UG 120 column (250 x 1.5 mm I.D.) with acetonitrile-phosphate buffer (20 mM, pH 7.0) (5:5, v/v) at a flow-rate of 0.1 ml/min. Total analysis time per sample was 18 min. The linearity of response was good (r=0.999) over the concentration range of 5-200 ng/ml. The within-day and day-to-day precision (CV) and inaccuracy were less than 3.7% and 3.8%, respectively. The mean recovery was 96.5+/-2.4% with the detection limit of 2 ng/ml.

Animals↗
PubMed1999

Epidermal growth factor system regulates mucin production in airways.

Goblet-cell hyperplasia is a critical pathological feature in hypersecretory diseases of airways. However, the underlying mechanisms are unknown, and no effective therapy exists. Here we show that stimulation of epidermal growth factor receptors (EGF-R) by its ligands, EGF and transforming growth factor alpha (TGFalpha), causes MUC5AC expression in airway epithelial cells both in in vitro and in vivo. We found that a MUC5AC-inducing epithelial cell line, NCI-H292, expresses EGF-R constitutively; EGF-R gene expression was stimulated further by tumor necrosis factor alpha (TNFalpha). EGF-R ligands increased the expression of MUC5AC at both gene and protein levels, and this effect was potentiated by TNFalpha. Selective EGF-R tyrosine kinase inhibitors blocked MUC5AC expression induced by EGF-R ligands. Pathogen-free rats expressed little EGF-R protein in airway epithelial cells; intratracheal instillation of TNFalpha induced EGF-R in airway epithelial cells, and subsequent instillation of EGF-R ligands increased the number of goblet cells, Alcian blue-periodic acid-Schiff staining (reflecting mucous glycoconjugates), and MUC5AC gene expression, whereas TNFalpha, EGF, or TGFalpha alone was without effect. In sensitized rats, three intratracheal instillations of ovalbumin resulted in EGF-R expression and goblet-cell production in airway epithelium. Pretreatment with EGF-R tyrosine kinase inhibitor, BIBX1522, prevented goblet-cell production both in rats stimulated by TNFalpha-EGF-R ligands and in an asthma model. These findings suggest potential roles for inhibitors of the EGF-R cascade in hypersecretory diseases of airways.

Animals↗
PubMed1999

Neurologic injury and recovery in patients with burst fracture of the thoracolumbar spine.

STUDY DESIGN: A retrospective study of factors affecting neural deficits and recovery in burst fracture of the thoracolumbar spine with an evaluation of the computed tomography scans and Frankel grades of 148 consecutive cases. OBJECTIVES: To evaluate the relation between the degree of traumatic canal impingement and neurologic improvement. SUMMARY OF BACKGROUND DATA: Previous studies on this subject have been reported, but the results have varied. METHODS: From 1986 to 1993, 148 consecutive cases of burst fracture of the thoracolumbar spine were evaluated by studying the following: 1) the cross-sectional area of the spinal canal by computed tomography scans, 2) damage to the posterior element of injured vertebra by computed tomography scans, 3) the neurologic deficits and improvement by Frankel grade. RESULTS: The average percentage of canal compromise was higher in the patients with neurologic deficit (52%) than in the patients with no neurologic deficit (35%). The degree of neurologic impairment was higher in the group with disruption of the posterior elements (62.9%) than in the group with intact posterior elements (29.8%). The degree of neural improvement was greater in the group with disruption of the posterior elements (60.7%) than in the group with no disruption of the posterior elements (25%). These differences were statistically significant (P < 0.05). CONCLUSION: The disruption of posterior elements indicated a more significant neurologically injured status on first examination; in those cases, however, the presence of disrupted posterior elements indicated a high possibility of neurologic recovery.

Adult↗
PubMed1999

Induction of Bax protein and degradation of lamin A during p53-dependent apoptosis induced by chemotherapeutic agents in human cancer cell lines.

In this study, subcellular fractionation analysis was performed to investigate the intracellular localization of Bax protein. We demonstrated that Bax protein is localized primarily in the nuclear and heavy membrane fractions. The expression of Bax protein in the nuclear membrane was induced in wild-type p53 human cancer cells (COLO 205 and Hep G2) by a wide variety of cancer chemotherapeutic agents in order to scrutinize further the biologic function of the Bax protein in the nuclear membrane. We found that lamin A and poly-(ADP ribose) polymerase (PARP) protein degradation coincided when the Bax protein level was elevated in the nuclear membrane of cells affected by drug stimuli. By using anti-sense oligodeoxynucleotides specific to human Bax mRNA, we further demonstrated that inhibition of Bax expression could specifically block lamin A but not PARP cleavage in apoptotic cancer cells.

Antineoplastic Agents↗
PubMed1999

Volatility of propoxur from different surface materials commonly found in homes.

The purpose of this study was to determine the volatilization rates of propoxur from different surface materials commonly found in homes, and to conduct field measurements under ventilated and non-ventilated conditions. Since it is known that temperature, humidity and constant air flow most significantly affect volatility, various surface materials were sprayed using a constant amount of propoxur under the controlled conditions of an exposure chamber. Acetonitrile was used to desorb both XAD-2 resin that collected airborne propoxur and surface materials containing propoxur residue. HPLC was used to analyze propoxur concentrations. Based on multiple regression models, temperature most significantly affected volatility, followed by humidity. Volatilization rates of propoxur were highest from quartz surfaces and lowest from glass. Interaction was most readily found on glass surfaces based on humidity-air flow and humidity-temperature factors. In field applications, propoxur was sprayed in a room under two conditions with ventilation and without in order to measure the concentrations of propoxur in the air and on a quartz surface. Findings showed both airborne and settled concentrations peaked after a half hour then decreased under both conditions, both more sharply in the ventilated room. Under both conditions, no propoxur was detected on the quartz surface after three and a half hours but airborne concentrations remained detectable after thirty-three and one half hours. We conclude that to maintain good air quality, ventilation is important and special care must be taken when spraying insecticides on different surfaces.

Air Pollution, Indoor↗
PubMed1999

Subjective visual experience during extracapsular cataract extraction and intraocular lens implantation under retrobulbar anaesthesia.

PURPOSE: To investigate the subjective visual experience of patients during cataract surgery under retrobulbar anaesthesia. METHODS: One hundred cataract patients who underwent routine extracapsular cataract extraction and intraocular lens implantation under retrobulbar anaesthesia were interviewed by the authors on the same day after their operation regarding their visual experience in the operated eye during surgery. RESULTS: Forty-three men and 57 women were included in the study. Their mean age was 68.4 years (range 40-87 years). Their pre-operative best corrected visual acuity ranged from 6/12 to perception of light. Eighty-four eyes had no other ocular pathology apart from cataract. Twenty patients reported no light perception during the surgery. The rest reported that they could see light (80 patients), one or more colours (56 patients), movements (39 patients), flashes (36 patients), instruments (16 patients) and/or the surgeon's fingers or hands (10 patients). The colours seen included red (29 patients), yellow (29 patients), green (12 patients), blue (11 patients) and orange (2 patients). Fifteen patients saw a spectrum of colours similar to that of the rainbow. Forty-four patients reported that the brightness of light changed during the operation. Five patients found their visual experience frightening. There was no correlation between those who found the experience frightening and the sex or age of patient, presence of coexisting ocular pathology, duration of operation, whether the operation was the first or second cataract operation in the patient, or the type of visual sensation experienced. CONCLUSION: Many patients undergoing cataract surgery under retrobulbar anaesthesia experience a variety of visual sensations that may be frightening in a small proportion of cases.

Adult↗
PubMed1999

Adenovirus-mediated interleukin-12 gene therapy for prostate cancer: suppression of orthotopic tumor growth and pre-established lung metastases in an orthotopic model.

Interleukin-12 (IL-12) can elicit potent antitumoral effects that involve the recruitment of specific immune effector cells. We investigated the efficacy of a single injection of a recombinant adenovirus expressing murine IL-12 (AdmIL-12) directly into orthotopic mouse prostate carcinomas generated from a poorly immunogenic cell line (RM-9) derived from the mouse prostate reconstitution system. Significant growth suppression (> 50% reduction of tumor weight) and increased mean survival time (23.4 to 28.9 days) were observed compared with controls. Suppression of pre-established lung metastases was also observed following the injection of AdmIL-12 into the orthotopic tumor. Cytolytic natural killer cell activity was markedly enhanced 1-2 days after virus injection. Immunohistochemical analysis showed significantly elevated intratumoral infiltration of CD4+ and CD8+ T cells 7 days after virus injection. However, splenocyte-derived cytotoxic T lymphocytes were not detected during the 14 days following treatment. Increased numbers of nitric oxide synthase-positive macrophages were seen in the AdmIL-12 treated group 7 days following injection. Systemic inhibition of natural killer cells with antiasialo-GM1 serum led to increased numbers of lung metastases in AdmIL-12-treated orthotopic tumors but did not affect local tumor growth. In this model system the antitumor effects of a single injection of adenovirus-mediated IL-12 appears to be based to a large extent on the activation of nitric oxide synthase in macrophages and possibly T cell activities, whereas the relatively early cytolytic activity of natural killer cells are largely but not exclusively responsible for the antimetastatic effects.

Adenoviridae↗
PubMed1999

The global nitrogen regulator NtcA regulates transcription of the signal transducer PII (GlnB) and influences its phosphorylation level in response to nitrogen and carbon supplies in the Cyanobacterium synechococcus sp. strain PCC 7942.

The PII protein is encoded by a unique glnB gene in Synechococcus sp. strain PCC 7942. Its expression has been analyzed in the wild type and in NtcA-null mutant cells grown under different conditions of nitrogen and carbon supply. RNA-DNA hybridization experiments revealed the presence of one transcript species 680 nucleotides long, whatever the nutrient conditions tested. A second transcript species, 620 nucleotides long, absent in the NtcA null mutant, was observed in wild-type cells that were nitrogen starved for 2 h under both high and low CO2 and in the presence of nitrate under a high CO2 concentration. Primer extension analysis indicated that the two transcript species are generated from two tandem promoters, a sigma70 Escherichia coli-type promoter and an NtcA-dependent promoter, located 120 and 53 nucleotides, respectively, from the glnB initiation codon. The NtcA-dependent promoter is up-regulated under the conditions mentioned above, while the sigma70 E. coli-type promoter displays constitutive levels of transcripts in the NtcA null mutant and slightly different levels in the wild-type cells, depending on the nitrogen and carbon supplies. In general, a good correlation between the amounts of the two transcript species and that of the PII protein was observed, as revealed by immunodetection with specific antibodies. The phosphorylation level of PII in the wild type is inversely correlated with nitrogen availability and directly correlated with higher CO2 concentration. This regulation is correspondingly less stringent in the NtcA null mutant cells. In contrast, the dephosphorylation of PII is NtcA independent.

Bacterial Proteins↗
PubMed1999

Vogt-Koyanagi-Harada disease: extensive vitiligo with prodromal generalized erythroderma.

The occurrence of vitiligo with prodromal erythema in Vogt-Koyanagi-Harada (VKH) disease is rarely observed. We describe a 68-year-old Chinese woman who developed extensive vitiligo 6 months after the onset of a generalized erythroderma and 12 months after the onset of acute bilateral uveitis. She also had a 4-year history of psoriatic plaques on the trunk which resolved completely without recurrence 15 months after the onset of erythroderma. The extensive cutaneous inflammation prior to the onset of vitiligo in our patient with VKH disease has not been reported before and strongly suggests an immunologic etiology for VKH disease.

Aged↗
PubMed1999

Stimulatory actions of insulin-like growth factor-I and transforming growth factor-alpha on intestinal neurotensin and peptide YY.

Proliferation of the gastrointestinal mucosa is stimulated by the growth factors, insulin-like growth factor-I (IGF-I) and transforming growth factor-alpha (TGF-alpha), or the closely related epidermal growth factor (EGF), as well as the gastrointestinal hormones, gastrin, neurotensin (NT), and peptide YY (PYY). The stimulatory actions of these growth factors or gastrointestinal hormones on the gastrointestinal mucosa may be direct or mediated in part by gastrointestinal peptides or the growth factors, respectively. The purpose of these studies therefore was to examine the effects of IGF-I and TGF-alpha on stomach gastrin and intestinal NT and PYY gene expression [i.e. messenger RNA (mRNA), peptide levels] and secretion. Mice were given recombinant human IGF-I (3, 6 mg/kg BW/day x 14 days). Transgenic mice with the rat TGF-alpha gene linked to a metallothionein promoter were used as a model of chronic TGF-alpha excess. IGF-I and TGF-alpha did not affect gastrin gene expression. Steady-state intestinal NT and PYY mRNA and peptide levels were elevated in a dose-related manner by IGF. TGF-alpha also increased intestinal expression of NT and PYY peptide, but not mRNA levels. Basal serum levels of PYY were elevated by IGF-I and TGF-alpha. IGF-I and TGF-alpha did not increase intestinal chromogranin A (CGA) gene expression, a marker of endocrine cells, or the density of PYY-containing cells in the colon, indicating that the elevations in intestinal gut peptide gene expression by IGF-I and TGF-alpha are not due simply to an increased number of enteroendocrine cells. IV infusion of EGF also stimulated release of PYY in the dog. Together, these findings indicate that IGF-I and TGF-alpha may cause secretion of gut hormones and exert a major upregulatory influence on the regulation of intestinal peptide hormone homeostasis.

Animals↗