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Biomedical subjects

Y C Lu

Publications and source records attributed to Y C Lu.

At least 19 recordsLinked to original sources
PubMed1992

Cutaneous angiocentric T-cell lymphoma associated with Epstein-Barr virus.

BACKGROUND: Two unusual cases of cutaneous angiocentric T-cell lymphoma were found to be associated with Epstein-Barr virus infection. OBJECTIVE: The objective was to study the clinical course and the response of the disease to conventional chemotherapy. METHODS: Histologic specimens from both patients were studied. Clonal proliferation was assessed by Southern blot hybridization. RESULTS: The disease in both patients was rapidly progressive and responded poorly to aggressive treatment. Biopsy specimens showed infiltration of atypical lymphoid cells with angiocentricity and angiodestruction, which probably resulted in the observed tissue necrosis. Clonal proliferation of Epstein-Barr virus DNA was detected in tissue from primary skin lesions and disseminated nasal lesions. CONCLUSION: Epstein-Barr virus-associated angiocentric T-cell lymphoma in our patients was characterized by an aggressive course and resistance to conventional chemotherapy. A search for Epstein-Barr virus and the human T-lymphotropic virus should be performed in patients with atypical features of cutaneous T-cell lymphoma.

Adult↗
PubMed1992

Biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions.

The present study was designed to investigate biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions. A three-dimensional finite element model of the upper central incisor was developed to analyze tooth displacements and stress distributions in the periodontal ligament. Lingual horizontal and apical vertical forces of 100 gf were applied at a point on the labial surface of the crown and at three different points on the lingual surface of the crown. Tooth displacements and stress distributions from the forces applied at the lingual points were compared with those from the labial force loading. The following results were obtained. 1. Lingual horizontal force produced almost similar patterns of tooth displacements and stress distributions, irrespective of labial and lingual application points of the orthodontic forces. 2. Apical vertical force applied at the lingual points produced more uniform tooth displacements and stress distributions than labial application of the force, although the force applied at the lingual point close to the cervix generated different patterns from those with the remaining lingual force loadings. The present results suggest an important role of the positional relation of force application points to the center of resistance. It is shown that lingual force application may produce more optimal tooth movement in terms of more uniform patterns of tooth displacements and subsequent stress distributions in the PDL.

Biomechanical Phenomena↗
PubMed1992

[A complete denture rebasing method in two appointments].

During rebase of the complete dentures, the denture bases are used as the trays for making border molding and final impression. Both open--mouth and closed-mouth impression methods are certainly expected to change the relationship between acrylic teeth and denture base after impression procedures. The upper denture usually shifts forward and downward, as a result, the occlusal relationship and esthetics are both damaged. The purpose of this article was to introduce an effective method for rebasing complete dentures. Through utilizing (1) the interridge distance, (2) the distance between the upper edentulous ridge and the occlusal surface of the lower acrylic teeth, and (3) the interocclusal records obtained immediately after each impression, the displacement of denture base can be corrected accurately. In addition, the original occlusion and esthetics are able to be preserved.

Denture Rebasing↗
PubMed1991

The NF kappa B independent cis-acting sequences in HIV-1 LTR responsive to T-cell activation.

The rate of transcription initiation directed by the long terminal repeat (LTR) of HIV-1 increases in response to mitogenic stimuli of T cells. Here we show that the response of the HIV-1 LTR may be governed by two independent sequences located 5' to the site of transcription initiation sequences that bind either NFAT-1 or NF kappa B. The rate of LTR-directed gene expression increased in response to treatment with either a phorbol ester or tumor necrosis factor alpha if either the NFAT-1 or NF kappa B binding sites were deleted, but failed to respond to these mitogenic stimuli if both sequences were absent. The HIV-1 mutant virus containing both NF kappa B and NFAT-1 deletion was able to replicate although at a much decreased growth rate, while the deletion of NFAT-1 alone increased the viral growth rate in Jurkat cells. Neither deletion of NF kappa B nor deletion of NFAT-1 decreased activation of viral replication by phorbol ester.

Cell Line↗
PubMed1990

Identification of cis-acting repressive sequences within the negative regulatory element of human immunodeficiency virus type 1.

The negative regulatory element of human immunodeficiency virus type 1 is a 260-nucleotide-long sequence that decreases the rate of RNA transcription initiation specified by the long terminal repeat. This region has the potential to bind several cellular transcription factors. Here it is shown that sequences which recognize the NFAT-1 and USF cellular transcription factors contribute to this negative regulatory effect. The sequences within the negative regulatory element which resemble the AP-1 site and the URS do not negatively regulate human immunodeficiency virus long terminal repeat transcription initiation.

Base Sequence↗
PubMed1990

Growth and characterization of normal human keratinocytes in F12 serum-free medium.

In a F12 medium supplemented with epidermal growth factor (20 ng/ml), insulin (5 micrograms/ml), transferrin (5 micrograms/ml), hydrocortisone (1 microM), cholera toxin (40 ng/ml), endothelial cell growth supplement (15 ng/ml) and retinoic acid (1 x 10(-7) M) on Vitrogen coated culture dishes, normal adult and newborn human foreskin keratinocytes were cultured for 4- and 2-time with population doublings (PD) accumulated as 8 and 12, respectively. The cells grown in this medium possessed a basaloid, undifferentiated and hyperproliferating nature, with a population doubling time of about 24 hours at early passage. Between the 1st and 2nd subcultures, cell proliferation was the most active. Delaying the time of first subculture lowered the rate of cell proliferation. The keratin of the cultured cells was studied by immunoblotting and revealed the presence of permanent keratin markers of the human skin (AE1 50 kDa and AE3 58kDa) as well as a relatively high intensity of a proliferating marker (AE1 48 kDa) and a relatively low intensity of a differentiation marker (AE3 67 kDa).

Adult↗
PubMed1989

Lipid peroxides, glutathione peroxidase, prostacyclin and cell cycle stages in normal and atherosclerotic Japanese quail arteries.

We have previously shown a negative correlation between lipid peroxide levels and prostacyclin synthesis in plasma and artery of the atherosclerotic rabbit. Here we compare the arterial lipid peroxide content, glutathione peroxidase activity, and prostacyclin and thromboxane production in response to exogenous arachidonic acid stimulation, and the cell cycle stages in normal and atherogenic diet-fed quail. Lipid peroxides were higher in arteries of the atherosclerotic quail, while glutathione peroxidase activity and prostacyclin and thromboxane production were lower than that in the control quail. The smooth muscle cell cycle distribution which was determined by flow cytometry according to DNA content showed that more than 14% of atherosclerotic arteries were mitotically active (in S + G2 + M phase), while less than 10% of control cells were active. These results suggest that there is a close relationship between lipid peroxide content, prostacyclin production and cell proliferation of the arterial wall in experimental atherosclerotic quail.

Animals↗
PubMed1989

Effect of hyperlipidemic serum on lipid peroxidation, synthesis of prostacyclin and thromboxane by cultured endothelial cells: protective effect of antioxidants.

An increased lipid peroxides and a decreased production of prostacyclin have been shown in advanced atherosclerotic lesions and plasma. Our purpose was to determine whether the similar findings could be observed in cultured endothelial cells, and whether antioxidants could protect the cell against peroxide injury. In these experiments we have used bovine aortic endothelial cells in culture to address the issue of hyperlipidemia-induced arterial damage. Results of the present study showed that different concentration of hyperlipidemic sera from atherogenic rabbits induced a time- and dose-dependent alteration in the production of prostacyclin and levels of lipid peroxides in endothelial cells. Endothelial cells incubated with hyperlipidemic serum increased prostacyclin generation significantly during the initial stages and then continuously decreased. When endothelial cells were incubated for 36 h, TXA2 generation was also impaired and at the same time the cellular lipid peroxides content increased. There was a positive correlation between the concentration of hyperlipidemic serum and lipid peroxides and an inverse correlation with prostacyclin synthesis. The medium supplemented with antioxidant selenium or vitamin E showed a significant decrease in lipid peroxides and an increase in prostacyclin synthesis. These results suggest that both hyperlipidemic serum and lipid peroxides injury endothelial cells and inactivate prostacyclin synthetase, resulting in a decrease of prostacyclin production, while antioxidants have a protective effect. We conclude that the increase in lipid peroxides in association with hyperlipidemia results in alteration of prostacyclin synthesis that may play an important role in the pathogenesis of atherosclerosis.

Animals↗
PubMed1989

Functional role of human immunodeficiency virus type 1 vpu.

To investigate the role of vpu in the replication and cytopathicity of human immunodeficiency virus type 1 (HIV-1), infectious proviruses were constructed that were isogenic except for the ability to produce the protein product of vpu. The vpu-encoded protein is shown to decrease the rate of syncytium formation and cell killing in infected CD4+ human T cells, to increase greatly the export of virus particles from infected cells, and to reduce the rate of accumulation of cell-associated viral proteins. The vpu protein complements in trans the defect in a vpu- HIV-1 provirus but does not affect the simian immunodeficiency virus, which lacks vpu. These observations suggest that vpu may contribute to the AIDS epidemic by increasing the transmission efficiency of the virus.

Base Sequence↗
PubMed1989

Antibodies to CD4 in individuals infected with human immunodeficiency virus type 1.

The attachment of human immunodeficiency virus type 1 (HIV-1) to target cells is mediated by a specific interaction between the viral envelope glycoprotein (gp120) and the CD4 receptor. Here we report that approximately 10% of HIV-1-infected individuals produce antibodies that recognize the extracellular portion of the CD4 molecule. Carboxyl-terminal deletions of CD4 that do not affect HIV-1 gp120 binding eliminate recognition of CD4 by patient antisera. In contrast, mutations in the amino-terminal domain of CD4 that attenuate HIV-1 gp120 binding do not diminish CD4 recognition by patient antisera. These results suggest that HIV-1 infection can generate antibodies directed against a region of the viral receptor distinct from the virus-binding domain.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Biological effect of qigong waiqi--a preliminary report of the anti-injurious effect of waiqi on ozone toxicity].

This paper deals with the anti-injurious effect of Qigong Waiqi on ozone toxicity. NIH male mice were randomly divided into three groups, O3 group, mice kept in 0.9 ppm O3 in a special room 12 hours/day for 12 days; Qigong group received Waiqi from a Qigong master for 30 minutes every morning in addition to what O3 group was treated; and a normal group for control. After 12 successive days, all the animals were decapitated and autopsy performed. Tissues taken from lung, liver, spleen and thymus were prepared for biochemical assay and microscopic examination. It was found that MDA content of lung and liver of O3 group was much higher than those of the control group and Qigong group. On the contrary, GSH-Px activity was significantly (P less than 0.001) lower than those of the control and Qigong groups. Both the MDA content and GSH-Px activity between the latter two groups were not significantly different. Microscopic examination revealed severe interstitial pneumonia with marked edema of lung and prominent leucocytic infiltration in liver of O3 group mice, but only slight changes were seen in Qigong group, so the differences were significant. The two immune organs of mice in O3 group were reduced in size and weight. Microscopic examination of immune organs of O3 group revealed thinner T lymphocyte population in cortex of thymus and periarterial sheath of spleen than those of Qigong group.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollution↗
PubMed1989

The skin manifestation of acute graft-versus-host disease: clinical and pathological analysis.

We report 11 cases of acute graft-versus-host disease (GVHD); 10 occurred after bone marrow transplantation (BMT) and one following transfusion of nonirradiated whole blood in a patient with severe combined immunodeficiency (SCID). According to the Seattle Classification, 5 cases were of Grade III, 2 Grade II, and 4 Grade I. The skin rash developed between the 6th to 47th day (22 +/- 12 day) after transplantation or transfusion, and was usually manifested initially as erythematous macules or papules in the neck or upper chest. The rash resolved in scaling or became purpuric, pigmented or erythrodermic in severe cases. The grading of skin pathology correlated well with clinical severity of GVHD. Four of the five who had advanced GVHD (Grade III) died. In all 4 cases but one (the SCID case), the skin pathology showed extensive basal vacuolization and multiple dyskeratotic cells. None of the others with mild or focal basal vacuolization and few dyskeratotic cells progressed into advanced GVHD. Three of the 5 cases with advanced GVHD received an underdose of cyclosporin A. These results suggest that severe GVHD carries a poor prognosis and an adequate dose of cyclosporin A is important in alleviating the severity of GVHD and reducing the mortality. The sero-virologic study performed during the skin rash period was negative, suggesting that the skin rash following BMT is mainly caused by GVHD and always precedes intestinal or hepatic manifestations.

Adolescent↗
PubMed1978

Serum immunoglobulin levels and tissue antibodies in psoriasis.

Serum samples from psoriatic patients were subjected to quantitation of serum IgA, IgG and IgM levels and screening of tissue autoantibodies including ANA, GPA, MTA and SMA. Serum IgA was found to be significantly elevated and incidences of ANA and GPA were also increased. Their significance and possible mechanism were discussed.

Adolescent↗
PubMed1978

Clinical studies on sporotrichosis in Taiwan.

A total of 59 cases, who visited the Dermatological Clinic of National Taiwan University Hospital in the past 27 years, was proved to be Sporotrichosis. The diagnostic criteria were the suggestive clinical pictures with any one of the following points: (1) positive fungal culture with characteristic colonies of Sporotrichum schenckii, (2) good therapeutic response to potassium iodide, (3) demonstration of fungal elements in the suggested pathological tissues or (4) demonstration of fungal elements in pus or tissue using direct immunofluorescence. All the informations concerning the clinical pictures and epidemiological points of view of these 59 patients were analysed. The chief cutaneous lesions were composed of nodules, ulcers or infiltrated plaques in linear arrangement on the exposed areas especially arms, legs or face. Thirty eight cases were male and 21 female. It affected peoples of the age between 4 to 70 years old, and their occupations were mainly outside workers such as agriculturist, worker, etc. Most of the affected people lived in the suburban areas of Taipei city such as Taoyuan and Taipei county. Serological tests such as precipitation, complement fixation and hemagglutination tests were performed in 12 cases, yet no reliable results were got.

Adolescent↗