Biomedical subjects

D Han

Publications and source records attributed to D Han.

At least 145 records · Page 8Linked to original sources

PubMed1996

Molecular characterization of Borrelia burgdorferi sensu lato from Slovenia revealing significant differences between tick and human isolates.

One hundred twenty-nine Slovenian isolates of Borrelia burgdorferi sensu lato derived from patients (69 strains) or Ixodes ricinus ticks (60 strains) were characterized. All of the strains were first- or second-passage isolates obtained in 1992 and 1993 from the same endemic region. The techniques used for the molecular analysis of strains included species-specific polymerase chain reaction (PCR) typing, and pulsed-field gel electrophoretic separation of undigested and MluI-digested genomic DNA. Isolates were identified to the species level by large restriction fragment pattern (LRFP) analysis and the results compared with the species-specific PCR result. Fifty-two patient isolates (75%) were typed as Borrelia afzelii (LRFP MLa1), 6 (9%) as Borrelia garinii (LRFPs MLg1-4), and 11 (16%) as Borrelia burgdorferi sensu stricto. The latter included 9 isolates (13%) with a new LRFP that is not typical of Borrelia burgdorferi sensu stricto and for which the designation MLx is suggested. In contrast, only 32 of 60 (53%) tick isolates were typed as Borrelia afzelii, while 20 strains (33%) were typed as Borrelia garinii and 8 strains (13%) as Borrelia burgdorferi sensu stricto. Three new LRFPs were found among the Borrelia garinii (MLg5 and 6) and Borrelia burgdorferi sensu stricto (MLb15) tick isolates. Large restriction fragment pattern analysis identified new groups of Borrelia burgdorferi sensu lato and revealed an apparent difference in the isolation frequency of different species from patients and ticks in the same endemic region.

Animals↗

PubMed1996

MR findings in human fascioliasis.

Fasciola hepatica is a trematode of herbivorous mammals, and man is infected by accidental ingestion of contaminated raw aquatic vegetables or water. There have been many reports on computed tomographic and cholangiographic features of human fascioliasis. However, findings of magnetic resonance (MR) imaging have not been reported. Hepatic fascioliasis produces three types of lesions in MR images arranged in tract-like fashion. The outermost area presents as an iso-signal area in T1WI, with slightly higher signal intensity in T2WI and diffuse enhancement after i.v. contrast. The second type presents as a well defined low signal area in T1WI, not enhanced, and also shows low signal intensity in T2WI. The third type has low signal intensity in T1WI, is not enhanced, and has high signal intensity in T2WI which is similar to fluid-containing inflammatory lesions such as pyogenic abscess. These findings suggest various changes associated with traumatic hepatitis caused by the migration of the worm in the liver. This diverse signal intensity can be a suggestive finding of fascioliasis.

Fascioliasis↗

PubMed1996

Decomposition of alpha-lipoic acid derivatives by photoirradiation-formation of dihydrolipoic acid from alpha-lipoic acid-.

Due to its strained five-membered ring, alpha-lipoic acid (LA) has an absorption band around 330 nm, which is used to quantify its concentration. In order to obtain information for the homolytic rupture of the S-S bond and the formation of dihydrolipoic acid (DHLA), the photochemical reaction of lipoic acid was examined in the presence or absence of ascorbic acid upon exposure to UVA light. The absorption band of alpha-lipoic acid at around 330 nm disappeared by photoirradiation, which corresponds to the rupture of S-S bond of the 1,2-dithiolane ring in lipoic acid. HPLC-Electrochemical Detection (ECD) analysis of lipoic acid showed significant formation of dihydrolipoic acid and other thiols. The formation of thiols from the photoreaction of lipoic acid was also confirmed by the Ellman method. The formation of thiols from lipoic acid was completely time-dependent and the formation of the thiols increased upto 55%. Similar results were obtained in the photochemical reactions of short-chain analogues, bisnor- and tetranor-lipoic acid. On the other hand, beta-lipoic acid was quite stable, no photodecomposition of beta-lipoic acid was observed in the UV region. The formation of thiols including dihydrolipoic acid from lipoic acid can be explained by considering the rupture of S-S bond, which results in the formation of the dithiyl radicals of alpha-lipoic acid. It is proposed that intra- and intermolecular hydrogen abstraction of the dithyl radical produces thiols including dihydrolipoic acid as final products.

Antioxidants↗

PubMed1996

[Effects of endoscopic sinus surgery and relative factors].

The results of 296 endoscopic sinus surgery (ESS) from Oct. 1991 to May, 1993 were analysed. Pre- and post-operative examinations in this series were as follows: 1. Peripheral blood T lymphocyte subclusters test (100 cases): 2. Immunohistochemical test of nasal polyp (103 cases): 3. Pathologic examination of nasal polyp: 4. CT scan typing (103 cases). Men and women ratio was 2:1 and their ages varied from 7 to 72 years. 107 patients were given general anesthesia and 189 patients local anesthesia. The clinical stages of chronic sinusitis were divided as: 53.7% (N), 29.3% (II), 10.9% (III) and 6.1% (I). The clinical curative rate was 85.7% (126/147 cases), and improving rate was 99.3%. The standard of clinical stage of chronic sinusitis, the relative factors of prognosis with the results of ESS, pathological test, immunohistochemical test and follow-up after ESS were discussed.

CD4-CD8 Ratio↗

PubMed1996

[Investigation of infiltrating lymphocytes and immunoglobulin by immunohistochemical method in cheilitis granulomatosa].

Category and distribution of infiltrating lymphocytes and immunoglobulin in 12 cases with cheilitis granulomatosa (CG) and 4 cases with Melkersson-Rosenthal syndrome (MRS) were investigated. The result was that infiltration of lymphocytes in granulomatous type was more severe than that in interstitial inflammtion type. Infiltrators mainly consisted of T helper lymphocytes and immunoglobulin was IgM. It was considered that local immunoreaction was enhanced suggesting that cyto-immunity was a dominant factor with participation of humoral immunity. The result will be helpful to elucidate the pathogeneses and the function of many immuno-factors in the CG. It helps to understand the clinical manifestations and may be a theoretic reference for seeking immuno-modulation for treatment.

Humans↗

PubMed1996

[The cellular immunologic status of the laryngeal cancer patients].

To observe the cellular immunologic status of the laryngeal cancer patients 70 laryngeal cancer patients were examined with immunohistochemical method. The peripheral blood T lymphocyte subsets were detected and local tumor infiltrative T lymphocytes were observed. The results showed that the cellular immunologic function of laryngeal cancer patients was lower than that of the healthy persons and the function of late staged patients was lower than that of the early staged patients. The pattern of changes of these two observations was of the same trend. The clinical significance of the examinations was discussed.

Adult↗

PubMed1996

[The relationship between human chorionic gonadotrophin and lipoprotein metabolism].

We compared human chorionic gonadotrophin (hCG-beta) with lipids, lipoproteins and apolipoproteins in serum between pre- and postmenopausal women, and observed the changes of levels of hCG-beta in animals suffering from hypertriglyceridemia. The results have shown that the concentration of hCG-beta in postmenopausal women is much higher than that in premenopausal women (P < 0.001). Correspondingly, triglyceride (TG) is elevated (P < 0.05). High density lipoprotein cholesterol (HDL-C) and HDL-C/LDL-C ratio are decreased (P < 0.001, P < 0.01). On the other hand, the tendency of highing hCG-beta level has been found in animal study. The concentration of hCG-beta in male rats suffering form hypertriglyceridemia is higher than that in normal animals (P < 0.05).

Adult↗

PubMed1996

[Treatment outcome of 1,000 cases of endoscopic sinus surgery].

To assess the treatment outcome of endoscopic sinus surgery (ESS), 1,000 patients with chronic sinusitis and nasal polyp treated between November 1991 and January 1995 were included in this study. Among them, 754 patients (64.8%) had previous operations from 1 to 25 times with an average of 3.7. Before ESS, axial and coronal CT scans were obtained (window width: 1,000 HU, window level: +90 HU; section thickness: 2 mm with 12 to 16 sections). Patients with clinical stages from I to IV were 9.9%, 21.0%, 15.0% and 54.1% respectively. Bilateral ESS was performed in 95% patients, septoplasty in 27.6%, middle meatal antrostomy in 78.5%. The clinical cure rate was 84.0%, 557 patients were considered as primary healing, 283 patients delayed healing and 160 patients had persistent inflammation. Complications were noted in 18 patients. Bleeding during ESS varied from 10 to 1,800 ml (average 180 ml). The indications, preoperative evaluation, control of bleeding, prevention of complications and prognosis were discussed in detail. The article indicated that the important factors to increase the cure rate are postoperative follow-up and systematic treatment.

Adolescent↗

PubMed1996

[Endoscopic CO2 laser treatment for the decannulation difficulty after vertical laryngectomy].

Sixteen patients with the decannulation difficulty after vertical laryngectomy were treated by endoscopic CO2 laser. The rate of decannulation was 87.5% (14/16). The curative effect was stable after 1-3 years. The causes of the decannulation difficulty included the over growth of granulation tissue, scar formation and bulky of the muscle flap. The result showed that endoscopic CO2 laser is an effective modality in the treatment of the decannulation difficulty after vertical laryngectomy.

Adult↗

PubMed1995

Age-related enhancement of tumor necrosis factor (TNF) production in mice.

We investigated age-related changes in the production of TNF at the cellular level using immunocompetent peritoneal and spleen cells from C3H/He mice of various ages. The density of cultured peritoneal macrophages and spleen cells required for TNF production was at least 5 x 10(5) cells/dish. The optimal concentration of OK-432 for 24-h culture of peritoneal macrophages (1 x 10(6) cells) and spleen cells (1 x 10(7) cells) was 0.5 and 0.1 KE/ml, respectively. Among peritoneal cells, adherent macrophages were the major TNF-producing cells, whilst nonadherent T or B cells alone did not produce TNF after stimulation with OK-432. In the case of spleen cells, T or B cells were involved in the production of TNF when cultured with a few adherent cells in the presence of OK-432. However, T or B cells alone failed to produce TNF. Production of TNF by peritoneal macrophages from both male and female mice increased significantly with aging. In contrast, although TNF production by spleen cells tended to increase with aging, no significant change was noted. The total number of peritoneal and spleen cells, respectively increased up to about 18 months after birth with B cells being principally responsible for this age-related increase. We previously reported that systemic production of TNF increases with aging. The present study of TNF production at the cellular level in mice indicated (1) that TNF production per macrophage increased with aging, and (2) that the number of T and B cells involved in the production of TNF in the presence of macrophages also increased at least up to middle age.

Aging↗

PubMed1995

Reduction and transport of lipoic acid by human erythrocytes.

Reduction of exogenous lipoic acid to dihydrolipoate is known to occur in several mammalian cells and tissues. Dihydrolipoate is a potent radical scavenger, and may provide significant antioxidant protection. Because lipoic acid appears in the bloodstream after oral administration, we have examined the reduction of exogenous lipoate by human erythrocytes. Normal human erythrocytes reduced lipoate to dihydrolipoate only in the presence of glucose; deoxyglucose did not substitute for glucose, indicating that the reduction of lipoate requires glucose metabolism. Furthermore, the reduction was shown to be NADPH dependent. Erythrocytes isolated from a human subject with a genetic deficiency of glucose-6-phosphate dehydrogenase (and, therefore, deficient in the formation of NADPH) did not reduce lipoate. Dehydroepiandrosterone, a specific inhibitor of glucose-6-phosphate dehydrogenase, inhibited lipoate reduction. Our findings imply that some of the reduction of exogenous lipoic acid is catalysed by glutathione reductase, a flavoprotein dehydrogenase; mitomycin C, an inhibitor of FAD-dependent reductases, inhibited lipoate reduction by erythrocytes, and glutathione reductase purified from human erythrocytes was observed to reduce lipoic acid in a cell-free system. We further explored these findings with erythrocyte ghosts and liposomes. Our results indicate that a transport system exists for alpha-lipoic acid and dihydrolipoate; resealed erythrocyte ghosts, containing trapped lipoamide dehydrogenase and pyridine nucleotides, reduced externally added lipoate. By contrast, liposomes prepared with enzyme and pyridine nucleotides did not catalyze reduction of lipoate. This work indicates that uptake of exogenous lipoate and reduction to dihydrolipoate by normal human erythrocytes may contribute to oxidant protection in the human bloodstream.

Biological Transport↗

PubMed1995

Distinction between binding of [3H]triamcinolone acetonide to a ligand binding domain on the glucocorticoid receptor complex in cytosol fractions of brain and liver from the rat with intact adrenals.

Binding of [3H]triamcinolone acetonide (TA) was examined to evaluate possible differences in biochemical and pharmacological profiles of a ligand binding domain on the naive glucocorticoid (GC) receptor complex between cytosol fractions of brain and liver obtained from the rat with intact adrenals. Unlabeled TA was 3-times less potent in displacing [3H]TA binding at equilibrium in the presence of Na2MoO4 at 2 degrees C in brain than in liver, while dexamethasone was more than 15-times more potent in displacing brain binding than liver binding. Both progesterone and aldosterone caused more than 20-times more potent displacement of [3H]TA binding in brain than in liver. However, zinc ions were effective in similarly inhibiting binding at equilibrium via lowering the affinity without affecting the density. In contrast to these experiments done at 2 degrees C, the addition of Na2MoO4 potentiated binding in brain and liver in a transient manner at 30 degrees C. Prolongation of incubation period from 30 min to 5 h induced a rightward shift of concentration-response curves of Na2MoO4 for [3H]TA binding at 30 degrees C in brain and liver in an irreversible fashion. The potentiation by Na2MoO4 was prevented by the addition of leupeptin but not 5 other protease inhibitors in brain cytosol fractions. Ion exchange chromatography revealed that elution profiles were entirely different from each other for [3H]TA binding between brain and liver cytosol fractions. These results suggest that GC receptors may respond to a variety of signals mediated by different steroid hormones through broader pharmacological spectrum of the ligand binding domain in brain than in liver.

Adrenal Glands↗

PubMed1995

Elucidation of antioxidant activity of alpha-lipoic acid toward hydroxyl radical.

The photosensitive organic hydroperoxide, NP-III, which produces hydroxyl radicals on illumination by UVA light, was used to examine the antioxidant activity of alpha-lipoic acid and its derivatives toward hydroxyl radical. Apolipoprotein (apo-B) of human low density lipoprotein (LDL) and bovine serum alubumin (BSA) were irradiated with UVA in the presence of NP-III and alpha-lipoic acid. The oxidation of BSA and the apo-B protein of LDL by NP-III was completely suppressed by alpha-lipoic acid. ESR studies using dimethylpyrroline oxide (DMPO) as a spin trapping reagent also revealed that in the presence of alpha-lipoic acid, the DMPO-OH adduct produced from the irradiation of NP-III and DMPO completely disappeared. DMPO-OH quenching experiments were performed in the presence or absence of desferoxamine but no change in the signal intensity was found. Hence, the quenching activity of alpha-lipoic acid is not due to its chelating activity toward transition metals (ferrous ions). The results lead us to conclude that alpha-lipoic acid is an efficient hydroxyl radical quencher owing to the disulfide bond in the dithiolane ring.

Antioxidants↗

PubMed1995

Alpha-lipoic acid increases intracellular glutathione in a human T-lymphocyte Jurkat cell line.

The addition of exogenous alpha-lipoic acid to cellular medium causes a rapid increase of intracellular unbound thiols in Jurkat cells, a human T-lymphocyte cell line. The rise of cellular thiols is a result of the cellular uptake and reduction of lipoic acid to dihydrolipoic acid and a rise in intracellular glutathione. Although the level of dihydrolipoic acid is 100-fold lower than glutathione, the cellular concentration of dihydrolipoic acid might be responsible for the modulation of total cellular thiol levels. Rises in glutathione correlate with the levels of intracellular dihydrolipoic acid (p < .01). This increase in glutathione is not the result of expression of new proteins like gamma-glutamylcysteine synthetase, since the rise in glutathione was not inhibited by cycloheximide, a protein synthesis inhibitor. Lipoic acid administration is therefore a potential therapeutic agent in an array of diseases with glutathione anomalies including HIV infection.

Cell Line↗

PubMed1995

Induction of protein oxidation in human low density lipoprotein by the photosensitive organic hydroperoxide, N,N'-bis(2-hydroxyperoxy-2-methoxyethyl)-1,4,5,8-naphthalene-tetra-carb oxylic- diimide.

We have developed a new molecular probe, N,N'-bis(2-hydroxyperoxy-2-methyoxyethyl)-1,4,5,8-naphthalen e-tetra-carboxylic- diimide (NP-III), that specifically generates hydroxyl radical upon irradiation with longer wavelength ultraviolet light (UVA). Hydroxyl radicals are generated only upon irradiation, thus NP-III is a new controllable hydroxyl radical source. Apolipoprotein (apo-B) of human low density lipoprotein (LDL), and bovine serum alubumin (BSA), were irradiated with UVA in the presence of NP-III and their oxidation was evaluated by two independent methods: assay of protein carbonyl groups and gel electrophoresis. NP-III oxidized apo-B and BSA in a time- and concentration-dependent manner. The results demonstrate that NP-III is a controllable, precise, and potentially tagetable source of hydroxyl radicals with which to induce protein oxidation.

Darkness↗

PubMed1995

Non random activation of endogenous interleukin-2, (IL-2), IL-2 receptor alpha and IL-2 receptor beta genes after transfection of mouse fibroblasts with a cDNA for the alpha chain of the human IL-2 receptor.

Mouse fibroblasts do not ordinarily express components for the interleukin-2 receptor (IL-2R alpha, beta, and gamma). An analysis of these cells by reverse transcription followed by polymerase chain reaction, however, indicates the presence of transcripts specific for the IL-2R beta and gamma genes. Transfection of the cDNA for the alpha chain of the human IL-2R into LTK- mouse fibroblast cell line (L3 cells) leads, in long-term cultures, to the formation of transcripts of endogenous mouse IL-2, IL-2R alpha and beta genes, as detected by Northern blotting. Based upon the results of the binding of 125I-labeled IL-2 to the transfected cells, three IL-2-binding proteins of 55 kDa, 65 kDa and 75 kDa were expressed by the transfected cells. The 65-kDa and 75-kDa proteins bound IL-2 in the presence of monoclonal antibodies for the IL-2R alpha chain. These polypeptides assembled to form high-affinity IL-2R, as shown by Scatchard binding analyses. The receptors were functionally active, since the expression of H-2k major histocompatibility complex antigens on the surface membranes of L3 cells was enhanced by exposing the cells to IL-2. Activation of the IL-2 gene was also observed in long-term cultures of L alpha beta cells, another LTK- transfectant expressing the human IL-2R alpha chain. This type of gene activation was not observed in LTK- fibroblasts transfected with cDNA for human IL-2 or IL-2R beta genes. In L3 and L alpha beta cells, transcription of the endogenous IL-2 gene was suppressed by cyclosporin A and enhanced by cycloheximide. These data may have implications for gene therapy of cancer cells.

Animals↗

PubMed1995

Analysis of reduced and oxidized lipoic acid in biological samples by high-performance liquid chromatography.

Using HPLC with electrochemical detection at a dual Hg/Au electrode, both reduced and oxidized lipoic acid can be measured in biological samples after addition of lipoic acid. The method does not detect bound lipoic acid, which must be liberated by strong acid or base hydrolysis. The detection limit for this HPLC method is 0.01 nmol of dihydrolipoate and 0.05 nmol of lipoate. Baseline separation of lipoate and dihydrolipoate is achieved on a 10 cm octadecyl column. The analysis is rapid (8 min/sample) and uses a single HPLC pump with isocratic mobile phase. The method has been adapted to study cellular and whole animal reduction of lipoate, membrane transport of lipoate and dihydrolipoate, and subcellular enzymes that reduce lipoate.

Cell Line↗

PubMed1995

Potentiation by calcium ions of [3H]MK-801 binding to an ion channel associated with the N-methyl-D-aspartate receptor complex in rat brain.

In vitro addition of Ca2+ ions was effective in almost doubling binding of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne (MK-801) before equilibrium to an ion channel associated with an N-methyl-D-aspartate (NMDA)-sensitive subclass of brain excitatory amino acid receptors. The addition of inhibitors for phospholipase (PLase) A2 markedly reduced binding in the absence of added Ca2+ ions, while Ca2+ ions restored the reduction to the level found in the absence of the inhibitors. Pretreatment with PLases A2 and C but not D was effective in potentiating [3H]MK-801 binding in a biphasic manner at a concentration range of 5 mU/ml-10 U/ml. Moreover, PLases A2 and C at low concentrations not only suppressed the abilities of 3 different agonists to potentiate [3H]MK-801 binding before equilibrium, but also reduced that of Ca2+ ions. These results suggest that Ca2+ ions may potentiate [3H]MK-801 binding to the NMDA channel highly permeable to Ca2+ ions through a mechanism common to that underlying potentiation by exogenous PLase A2 and/or C.

2-Amino-5-phosphonovalerate↗