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Biomedical subjects

S H Han

Publications and source records attributed to S H Han.

At least 127 records · Page 7Linked to original sources
PubMed1998

[Histopathology of Anopheles gambiae s.l. Giles, 1902 (Diptera, Culicidae) subjected to the larvicidal activity of the aqueous extract of Persea americana Miller, 1768 (Lauraceae)].

Larvae of Anopheles gambiae treated with an aqueous extract of Persea americana suffer important damages of the midgut. The first epithelial cells to be affected are those at the posterior part of the midgut which become hypertrophic after only 30 min. After one hour most of the cells in this part lyse. The cytoplasmic material is then rejected towards the lumen gut, between the peritrophic membrane and the midgut epithelium. Subsequently, an almost total cell degeneration is observed. Cells of gastric caeca and cells at the intermediary and anterior parts of the midgut undergo the same histopathology, albeit after a longer period.

Animals↗
PubMed1998

Airway hyperreactivity modulated by immunotherapy with denatured ovalbumin in ovalbumin-sensitized guinea pigs.

Denatured immunogenic peptides have recently been used successfully to treat autoimmune disease in mice. Their effect on airway response is unclear. In this study, we compared the effect of native ovalbumin (OVA) and denatured ovalbumin (DN-OVA) on airway spasm and hyperreactivity in guinea pigs. The effects of immunotherapy using DN-OVA were also investigated. Airway response to antigen was determined in conscious, nose-breathing guinea pigs. Results showed that animals could be sensitized by repeated exposure to OVA, but not DN-OVA. Following OVA exposure in OVA-sensitized guinea pigs, airway resistance was significantly increased in both early (30 min, 118.8% +/- 34.2%) and late (6 h, 91.1% +/- 30.1%) phases. Tidal volumes were reduced in both early (47.5% +/- 12.0%) and late (43.8% +/- 10.3%) phases. This dual-phase airway spasm could not be induced by DN-OVA. In addition, there was no change in pulmonary function noted after DN-OVA exposure in OVA-sensitized guinea pigs. OVA-induced airway response was modulated by immunotherapy with subcutaneous DN-OVA administration for 3 weeks. OVA-specific IgG was also increased after immunotherapy. However, there was no significant change in pulmonary function after oral administration of DN-OVA in OVA-sensitized guinea pigs. We conclude that OVA, but not DN-OVA, can successfully induce dual-phase airway spasm in guinea pigs. These reactions can be modulated by immunotherapy with subcutaneously administered DN-OVA.

Animals↗
PubMed1998

Transforming growth factor-beta 1 (TGF-beta1) promotes IL-2 mRNA expression through the up-regulation of NF-kappaB, AP-1 and NF-AT in EL4 cells.

Transforming growth factor beta1 (TGF-beta1) has been previously shown to modulate interleukin 2 (IL-2) secretion by activated T-cells. In the present studies, we determined that TGF-beta1 induced IL-2 mRNA expression in the murine T-cell line EL4, in the absence of other stimuli. IL-2 mRNA expression was significantly induced by TGF-beta1 (0.1-1 ng/ml) over a relatively narrow concentration range, which led to the induction of IL-2 secretion. Under identical condition, we examined the effect of TGF-beta1 on the activity of nuclear factor AT (NF-AT), nuclear factor kappaB (NF-kappaB), activator protein-1 (AP-1) and octamer, all of which contribute to the regulation of IL-2 gene expression. Electrophoretic mobility shift assays showed that TGF-beta1 markedly increased NF-AT, NF-kappaB and AP-1 binding to their respective cognate DNA binding sites, whereas octamer binding remained constant, as compared with untreated cells. Employing a reporter gene expression system with p(NF-kappaB)3-CAT, p(NF-AT)3-CAT and p(AP-1)3-CAT, TGF-beta1 treatment of transfected EL4 cells induced a dose-related increase in chloramphenicol acetyltransferase activity that correlated well with the DNA binding profile found in the electrophoretic mobility shift assay studies. These results show that TGF-beta1, in the absence of any additional stimuli, up-regulates the activity of key transcription factors involved in IL-2 gene expression, including NF-AT, NF-kappaB and AP-1, to help promote IL-2 mRNA expression by EL4 cells.

Animals↗
PubMed1997

The expression of genes modulating programmed cell death in normal human polymorphonuclear neutrophils.

Normal human polymorphonuclear neutrophils (PMN) have a short life and die in progression via apoptosis. In order to understand the molecular basis of PMN apoptosis, the expression of apoptosis-related (Fas, Fas-ligand, p53, and c-myc) and survival-related (bcl-2) genes was detected by flow cytometry, Western blot and reverse transcription-assisted polymerase chain reaction (RT-PCR). We found that Fas and Fas-ligand (FasL) were expressed on the surface of most of the cells. However, the disappearance of FasL was much faster than Fas after 24 h incubation. p53 and bcl-2 were also expressed in the cytoplasm of most of the cells. In contrast, the expression of c-myc was negligible in PMN. The addition of monoclonal anti-human Fas antibody (25 micrograms/ml) to PMN suspension enhanced whereas anti-FasL antibody (25 micrograms/ml) suppressed PMN apoptosis in 48 h incubation. These results suggest that the activation of Fas pathway induced by Fas-FasL interaction among PMNs is one of the mechanisms for spontaneous PMN apoptosis. Lack of proto-oncoprotein c-myc expression in PMN is responsible for their non-proliferative property and may aggravate the spontaneous apoptosis of the cells.

Animals↗
PubMed1997

Induction of liver-associated transforming growth factor beta 1 (TGF-beta 1) mRNA expression by carbon tetrachloride leads to the inhibition of T helper 2 cell-associated lymphokines.

Acute treatment of B6C3F1 mice with a hepatotoxic dose (500 mg/kg) of carbon tetrachloride (CCl4) produced a marked but transient increase in transforming growth factor beta 1 (TGF-beta 1) mRNA expression in the liver within 24 hr. We have previously shown that an identical dose of CCl4 also produces a marked increase in serum TGF-beta 1 concentrations which peak at 48 hr and produce a marked inhibition of the anti-sRBC IgM antibody forming cell (AFC) response. Similar increases in TGF-beta 1 transcripts scripts in the liver were also induced by an acute hepatotoxic dose (600 mg/kg) of acetaminophen. No increase in TGF-beta 1 mRNA expression was detected in the spleen following treatment with either agent. Direct addition of TGF-beta 1 (0.05-1.0 ng/ml) to naive splenocyte cultures produced a marked and dose-related inhibition of the anti-sRBC IgM AFC response. Under the same conditions, TGF-beta 1 induced a marked decrease in IL-4 and IL-5 mRNA expression in sRBC-sensitized splenocytes. Concomitantly, TGF-beta 1 induced a rapid increase in NF-kappa B/Rel trans-acting factor binding within the first 24 hr post-sRBC sensitization of splenocytes. Conversely, NF-kappa B/Rel binding activity was inhibited on Days 2 through 4 in sRBC-sensitized splenocytes in the presence of TGF-beta 1. The increase in NF-kappa B/Rel binding within 24 hr following sRBC sensitization is consistent with the positive influence TGF-beta 1 exerts on Th1 cytokines such as IL-2 and IFN-gamma. Conversely the decrease in NF-kappa B/Rel binding at the later time period during the AFC response (Days 2-4) coincides with the inhibitory effects TGF-beta 1 exerted on IgM production by B cells.

Acetaminophen↗
PubMed1997

Tamm-Horsfall glycoprotein (THG) is a binder for surface membrane proteins on blood cells and glomerular mesangial cells.

A macromolecule with a molecular weight of 90-100 kDa was purified from normal human pregnancy urine. The molecule was proved to be the Tamm-Horsfall glycoprotein (THG) by Western blot analysis. The macromolecule contains carbohydrate as detected by an enzyme immunoassay. Functionally, the glycoprotein can adhere to and stimulate the thymidine incorporation of human mononuclear cells (MNC) in modest degree via its membranotropic property. In addition to MNC, the protein can also bind to the surface of human polymorphonuclear neutrophils (PMN), red blood cells (RBC) and rat glomerular mesangial cells (RMC). Western blot analysis of various cell lysates with/without proteinase K pretreatment before cell lysis revealed that a 60 kDa and a molecule larger that 94 kDa on the surface of PMN, a 60 kDa protein on MNC and a 32 kDa protein on RBC are the binding molecules for THG. In contrast, many proteins on the surface of RMC could be bound by THG. Immunoprecipitation of membranous iodinated MNC lysates also confirmed that the 60 kDa molecule on MNC is the binding protein for THG. A number of monosaccharide including N-acetylneuraminic acid, N-acetyl-galactosamine, N-acetyl-glucosamine and alpha-methyl-D-mannoside could not inhibit the mitogenic effect of THG on human mononuclear cells. These results suggest that THG is capable of reacting with surface membrane proteins on different cells, but not through the specific carbohydrate-containing lectin-like receptors on the cell surface.

Animals↗
PubMed1997

Using monoclonal antibodies to characterize a sequential epitope on the group I allergen of Bermuda grass pollen.

BACKGROUND: Cyn d 1, the group I allergen of Bermuda grass pollen, had been purified and characterized. METHODS: A sequential B cell epitope on Cyn d 1 was studied with monoclonal antibodies (MoAbs). Cyn d 1 was cleaved by Achromobacter protease I into fragments, and the resulting peptides were fractionated on reversed-phase columns before being reacted with anti-Cyn d 1 MoAbs in a radioimmunoassay. A Cyn d 1 fragment recognized by its MoAb was selected for Edman degradation. A synthetic peptide was constructed according to the determined sequence. RESULTS: The epitope on Cyn d 1 recognized by MoAb 18-53 was found to be conformation independent, since its activity was not changed after sodium periodate, guanidine or urea treatment. The enzyme-cleaved fragment containing this epitope was determined to be DVDKPPFDGMTACGNEPIF which corresponds to the N-terminal 46-64 residues of Cyn d 1. The presence of this sequence in the epitope recognized by MoAb 18-53 was demonstrated by enzyme immunoassay and further confirmed by inhibition of binding enzyme immunoassay with synthetic peptides. Some cross-reactivity with the N-terminal 45-63 residues of Lol p 1 was also found. CONCLUSIONS: The primary structure of a sequential epitope on Cyn d 1 was determined, and its activity was confirmed with peptides synthesized according to the determined sequence.

Allergens↗
PubMed1997

Characterization of the 33-kilodalton major allergen of Penicillium citrinum by using MoAbs and N-terminal amino acid sequencing.

BACKGROUND: The 33 kD component has been identified as a major allergen of Penicillium citrinum, the most prevalent Penicillium species in the Taipei area of Taiwan. OBJECTIVE: This study analyses the isoforms, antigenic cross-reactivity and the N-terminal amino acid sequence of the 33 kD allergen of P. citrinum. METHODS: The composition of isoforms and antigenic cross-reactivity was analysed by SDS-PAGE and 2D-immunoblotting using MoAbs generated. The N-terminal sequence was analysed by using an automatic gas/liquid phase sequencer. RESULTS: Two MoAbs (55A and 34H) against the 33 kD allergen were generated in the present study. In addition to the 33 kD component, MoAb 34H also showed immunoblot reactivity to other components in the crude extract of P. citrinum. Analysed by 2D-immunoblotting, at least six different isoforms of the 33 kD component with pI values ranging from 6.75 to greater than 7.0 were shown to be reactive to both MoAbs and IgE antibodies in serum of an asthmatic patient. Different immunoblot patterns were observed when both MoAbs were reacted with four different strains of P. citrinum used in the present study. Among another six different Penicillium and four different Aspergillus species tested, only an immunoblot reactivity of MoAb 55A to the 33 kD component of P. brevicompactum was observed. In 2D-immunoblotting, components of P. brevicompactum with an MW of about 33 kD and pI values similar to those of the 33 kD component of P. citrinum reacted with MoAb 55A and IgE antibodies in serum of the asthmatic patient. The N-terminal amino acid sequence of the 33 kD component of P. citrinum was determined to be ANVVQSNVP which was identical to the first 9 N-terminal amino acids of a heat-labile alkaline serine proteinase from P. citrinum. CONCLUSION: Results obtained in the present study suggest that the 33 kD major allergen of P. citrinum may be an alkaline serine proteinase.

Allergens↗
PubMed1997

Molecular cloning and expression of a Penicillium citrinum allergen with sequence homology and antigenic crossreactivity to a hsp 70 human heat shock protein.

BACKGROUND: Penicillium citrinum has been identified as the most prevalent airborne Penicillium species in the Taipei area. However, detailed studies on allergens of this ubiquitous Penicillium species are still lacking. OBJECTIVE: For the characterization of allergens of this prevalent Penicillium species, molecular cloning and expression of the allergen genes of P. citrinum were performed in the present study. METHODS: Molecular cloning of the allergen genes was performed by using a lambda Uni-Zap XR cDNA library of P. citrinum and serum from an asthmatic patient. The cloned cDNA was excised from the phage vector as a recombinant pBluescript phagemid and sequenced. The cDNA of the IgE-binding clone was expressed as fusion protein with the glutathione-S-transferase. The corresponding natural allergen was analysed by absorption immunoblotting using monoclonal antibody and serum from asthmatic patient. The frequency of IgE-binding to the allergen cloned was analysed by dot immunoassay using recombinant allergen and by immunoblotting using the whole extract of P. citrinum. RESULTS: In the screening of cDNA library of P. citrinum using serum from an asthmatic patient, IgE-binding cDNA clones designated SC4 and XL were obtained. The 5'-truncated, 0.7-kb and 1.7-kb cDNA inserts of clones SC4 and XL contained open reading frames of 163 and 503 amino acids, respectively. On alignment, the deduced amino acid sequences showed that 97 (60%) of the 163 amino acids and 376 (75%) of the 503 amino acids were identical to the corresponding amino acid sequence of the human heat shock protein in the hsp70 family. Both recombinant SC4 and XL showed positive SDS-PAGE-immunoblot reactivity to a monoclonal antibody MA3-006 against the human hsp 70 protein. For characterization of the corresponding natural allergen, immunoblotting reactivities of MA3-006 and IgE antibodies to the 70 kDa component of P. citrinum have been shown to be disappeared after absorption of these antibodies with the recombinant SC4 protein. Sera from 14 (41%) of 34 Penicillium-allergic patients showed IgE-binding to the recombinant XL protein and the 70 kDa component in the extract of P. citrinum. CONCLUSION: Results obtained suggest that hsp 70 is an allergen of P. citrinum and that clones SC4 and XL contain partial cDNAs of this allergen gene.

Allergens↗
PubMed1997

Effect of iron depletion on long-term response to interferon-alpha in patients with chronic hepatitis C who previously did not respond to interferon therapy.

About half of patients with chronic hepatitis C treated with interferon will not have a biochemical or virological response. Several studies suggested that increased hepatic iron content may negatively influence the response to interferon. We conducted this prospective trial to evaluate the effect of iron depletion on the response to a repeat course of interferon in 20 chronic hepatitis C patients who previously had not responded to interferon. The patients underwent 500-ml phlebotomies every 2 weeks until iron deficiency was achieved. Patients were then started on a 6-month course of interferon alfa-2b (3 million units, t.i.w.). These patients required a mean of 6.0 (range, 1-14) phlebotomies to become iron deficient. ALT levels decreased in 18 of 20 patients and became normal in 4 patients. Mean ALT levels decreased from 154.2 to 87.9 U/L (p = 0.0006). At the end of 24 wk of interferon therapy, ALT levels were normal in 11 patients, 3 of whom had undetectable HCV RNA in the serum. One additional patient with abnormal ALT had undetectable HCV RNA. After 6 months of follow-up, one of the HCV RNA negative patients relapsed with reappearance of HCV RNA and elevation of ALT. In summary, 15% of chronic hepatitis C patients who previously failed interferon now had a sustained response to interferon therapy that was preceded by iron depletion.

Adult↗
PubMed1996

Morphological, biochemical, and genetic support for an apolipoprotein E effect on microtubular metabolism.

There are two distinct viewpoints on the association of the inheritance of apolipoprotein E (APOE) alleles and the age of onset distribution of Alzheimer's disease (AD): genetic and phenotypic expression. There have been multiple corroborations of the APOE-epsilon 4 association with Alzheimer's disease in populations around the world in clinic based studies as well as emerging epidemiological studies. The genetic data do not imply mechanism of pathogenesis. The phenotypic expression of AD has been based in theories based on amyloid plaques or neurofibrillary tangles. ApoE protein interacts with both beta-amyloid and tau in an isoform-specific manner. The interaction with tau had been thought to be an in vitro artifact, since apoE had not been previously localized to the neuronal cytoplasm. Immuno-EM studies have localized apoE in neuronal cytoplasm. ApoE3 interacts with both tau and MAP2c at the microtubule binding repeat domain under conditions in which apoE4 is less tightly bound. These data further support a hypothesis that apoE3 (and apoE2) protect the microtubule binding domain of tau from binding to itself to form paired helical filaments and neurofibrillary tangles, while protecting the site for microtubule stabilizing interactions with beta-tubulin. These data are supported by recent data from APOE knock-out mice demonstrating dendritic alterations leading to synaptic simplification similar to that observed in AD.

Age of Onset↗
PubMed1996

Thiamine administration during chronic alcohol intake in pregnant and lactating rats: effects on the offspring neurobehavioural development.

A number of mechanisms may be involved in the pathogenesis of thiamine deficiency in the alcoholic. Among these mechanisms are inadequate dietary intake of thiamine, impaired intestinal transport of the vitamin and decreased conversion of thiamine to the active coenzyme. The present study was undertaken to further investigate the mechanism by which alcohol can interfere with thiamine deficiency in the brain. Thus, the neurobehavioural development of rat pups (E) nursed by 12% ethanol/water-drinking mothers, or pups (E-T) nursed by mothers drinking 12% ethanol/water + thiamine hydrochloride mixture, was monitored from the 1st to 45th postnatal days. Appropriate pair-fed saccharose (S) and ad libitum controls (C) were assessed. Histological studies were performed at the age of 45 days on the hippocampal CA3 pyramidal neurons of the offspring from each treatment. Exposing rat pups to ethanol during pregnancy and lactation showed a significant impairment of neurobehavioural development, more cornered pyramidal cells in the hippocampal field CA3, reduced cell number and cell size. The results point out long-lasting effects of maternal alcohol exposure in the offspring. Both functional and structural studies showed that neurotoxic effects of developmental alcohol exposure were not reversed by thiamine administration. However, adverse effects of undernutrition following developmental alcohol exposure were suppressed by thiamine administration. From this work, we suggest that inadequate dietary intake of thiamine and impaired intestinal transport of the vitamin are not critical mechanisms leading to thiamine deficiency in chronic alcoholism. The most prevalent mechanism contributing to ethanol-induced thiamine deficiency in chronic alcoholics would be the alteration of thiamine metabolism, and particularly the reduction of the vitamin conversion to its metabolically active form TPP (thiamine pyrophosphate).

Animals↗
PubMed1996

A clinical study of the natural remodeling of burst fractures of the lumbar spine.

Surgical decompression and fixation are considered by many to be the preferred treatment for burst fractures of the lumbar spine, regardless of neurologic deficit. For 6 patients with burst fracture of the lumbar spine but without neurologic deficit, computed tomography scans revealed >50% encroachment of the spinal canal. All 6 patients were treated conservatively, and during the followup period (range, 6-49 months), the narrowing of the spinal canal decreased progressively because of resorption of the fragments and natural remodeling. The presence of a neurologic deficit should be the primary indication for surgery in patients with a burst fracture of the lumbar spine.

Adult↗
PubMed1996

Menstrual and reproductive factors related to the risk of breast cancer in Korea. Ovarian hormone effect on breast cancer.

To support the ovarian hormone hypothesis in the etiology of breast cancer, a hospital-based case-control study with community controls was conducted to evaluate the relationship of intervals among menstrual and reproductive events to the risk of breast cancer in Korea. The cases were 190 breast cancer patients, who had been histologically diagnosed at Seoul National University Hospital from Jan. 1, 1993 to Jun. 30, 1994. Included were cancer-free women, who had undertaken the Gynecological examination at the same hospital (n=190). Women recruited for a survey of diabetes prevalence in Yonchon County, adjacent to Seoul City, were taken as a community control group (n=190). Information on menstrual and reproductive factors with other life-styles was collected through a direct interview by the well-trained interviewers. The adjusted odds ratios and the 95% confidence intervals were based on the unconditional logistic regression model. Likelihood ratio test for trend was applied for the ordinal variables. Early age at menarche, late age at natural menopause, late age at first full term pregnancy, and fewer number of full term pregnancies are independently associated with the high risk of breast cancer in Korea. Moreover, the interval between the age at menarche and the age at natural menopause of community controls (29.9+/-6.15 years) was significantly shortened compared to breast cancer cases (34.9+/-4.42 years). Particularly noteworthy was that intervals between the age at menarche and the age at first full term pregnancy of both control groups (9.0+/-3.72 years for hospital controls; 7.2+/-4.04 years for community controls) were significantly shortened compared to breast cancer cases (11.0+/-4.51 years). These findings support the hypothesis that the longer exposure to ovarian hormones during the reproductive years, the higher the risk of breast cancer.

Adult↗
PubMed1996

Allergenic components in three different species of Penicillium: crossreactivity among major allergens.

BACKGROUND: Penicillium species have been considered as important causative agents of extrinsic bronchial asthma. However, little is known about the allergens of these ubiquitous airborne fungal species. OBJECTIVE: This study compares the allergenic profiles and allergenic crossreactivity among allergens of three prevalent airborne Penicillium species. METHODS: IgE-binding Penicillium components were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-immunoblotting using sera from 67 asthmatic patients. The presence of allergenic crossreactivity was analysed by immunoblot inhibition. RESULTS: Among the 67 serum samples tested, 15, 14 and 11 samples showed IgE reactivity to components of P. citrinum, P. notatum and P. brevicompactum, respectively. All 15 P. citrinum-positive serum samples showed IgE-binding to a 33 kDa extract component of this species. Thirteen (93%) of the 14 P. notatum-positive serum samples and 10 (91%) of the 11 P. brevicompactum-positive sera also showed IgE reactivity to components with a molecular weight of about 33 kDa in individual Penicillium species. All of the 10 P. brevicompactum 33 kDa component-positive serum samples showed IgE reactivity to the 33 kDa components of the other two Penicillium species tested. Dose-dependent inhibition of IgE-binding to these major allergens was observed when the positive serum sample was absorbed with different amounts of individual allergenic extract as well as with different amounts of extracts prepared from the other two Penicillium species. CONCLUSION: Although different allergenic profiles were observed in the three different Penicillium species tested, results showed that there was an IgE crossreactivity among the 33 kDa group major allergens of P. citrinum, P. notatum and P. brevicompactum.

Allergens↗