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L S Chan

Publications and source records attributed to L S Chan.

At least 109 records · Page 6Linked to original sources
PubMed1992

Human dermal fibroblast interleukin-1 receptor antagonist (IL-1ra) and interleukin-1 beta (IL-1 beta) mRNA and protein are co-stimulated by phorbol ester: implication for a homeostatic mechanism.

Although the major functions of fibroblasts are to produce extracellular matrix and to maintain a structural framework for organ systems, recent studies have demonstrated that fibroblasts are active participants in inflammatory processes by synthesizing various inflammatory mediators. In this report, we provide evidence that fibroblasts may contribute to the regulation of inflammation by the synthesis of both the intracellular form and the secretory form of interleukin-1 receptor antagonists in conjunction with interleukin-1 beta production. Indirect immunofluorescence microscopy localized interleukin-1 receptor antagonist and interleukin-1 beta proteins primarily in the fibroblast cytoplasm. Polymerase chain reaction amplification of reverse-transcribed mRNA with primers specific for the intracellular form of interleukin-1 receptor antagonist detected cDNA fragments present in both unstimulated and phorbol ester-stimulated fibroblasts, identical in molecular size to that in unstimulated keratinocytes. Amplification with primers specific for the secretory form of interleukin-1 receptor antagonist, however, detected cDNA fragments in phorbol ester-stimulated fibroblasts and phytohemagglutinin-stimulated peripheral mononuclear cells, but not in unstimulated fibroblasts or keratinocytes. The amplified fibroblast cDNA sequences for both intracellular and secretory interleukin-1 receptor antagonists were confirmed by digestion with three restriction endonucleases. By ethidium bromide visualization of amplified cDNA derived from serially diluted total cellular RNA and by Southern blot hybridization analysis of amplified cDNA, we have demonstrated that fibroblast interleukin-1 receptor antagonist mRNA and interleukin-1 beta mRNA were co-stimulated by phorbol ester. Similarly, ELISA demonstrated that fibroblast cytoplasmic interleukin-1 receptor antagonist protein and interleukin-1 beta protein were co-stimulated by phorbol ester. Our data suggests that the intracellular form of interleukin-1 receptor antagonist may be important in maintaining physiologic homeostasis in fibroblasts during interleukin-1 beta induction and release.

Base Sequence↗
PubMed1992

Interleukin-1 receptor antagonist in normal and psoriatic epidermis.

The objective of these studies was to characterize the IL-1 inhibitory activity present in normal and psoriatic epidermis from clinically stable lesions. Fractionation of normal epidermal cytosol on a molecular sizing column failed to reveal the presence of IL-1 inhibitory bioactivity. However, specific ELISAs indicated that both the IL-1 receptor antagonist (IL-1ra) and IL-1 alpha were present in overlapping peaks. Further fractionation of the normal epidermal cytosol by anion exchange chromatography separated these two molecules, revealing the IL-1 inhibitory bioactivity of the IL-1ra molecule. Similar studies on psoriatic epidermal cytosol indicated the presence of IL-1 inhibitory bioactivity and IL-1ra protein. The IL-1 inhibitory bioactivity of both normal and psoriatic cytosol was neutralized by a mAb specific for IL-1ra. The ratio of IL-1ra to IL-1 alpha proteins was significantly increased in involved psoriatic skin compared with normal skin. By Western blot analysis this IL-1ra was approximately 20 kD, slightly larger than monocyte-derived IL-1ra and equivalent to an intracellular variant of IL-1ra expressed by keratinocytes. Polymerase chain reaction indicated the presence of mRNA for both forms of IL-1ra in normal epidermis, with both forms increased in psoriatic-involved skin. Immunofluorescence studies revealed the IL-1ra protein to be concentrated in the stratum granulosum of normal skin and in the basal-midbasal layers of psoriatic epidermis. These results suggest that the balance between intracellular IL-1ra and IL-1 alpha may be an important influence on keratinocyte growth and/or differentiation, as well as on the inflammatory potential of IL-1 in injured skin.

Antibodies, Monoclonal↗
PubMed1992

Scanning electron microscopy of odontogenic cyst epithelium.

The epithelial lining of 8 odontogenic keratocysts (OKC), 9 radicular (RC) and 3 dentigerous cysts (DC) were examined in SEM in order to study the ultrastructural surface topography of the lumenal surface cells. The orthokeratinized OKC showed a reticular network of intercommunicating microridges surrounding micropits giving a honeycombed appearance to the entire surface. The deep surface of these cells was covered by a complementary array of short stubby microvilli. This pattern was identical to that described for oral epithelium in areas of masticatory mucosa. The parakeratinized OKC showed a complex pattern of microplications (MP) on both upper and deep cell surfaces. The non-keratinized linings of RC and DC revealed a similar MP pattern but of a less complex nature. The MP pattern of cells from para- and non-keratinized cysts was identical to that described for oral epithelial cells from lining mucosa. The surface ultrastructure of ciliated, mucus and brush cells occurring in RC was found to be indistinguishable from that described in the mammalian respiratory tract. The MP pattern forms part of the cellular interdigitation mechanisms in stratified squamous epithelium. Differences in the ultrastructural configuration are related to the type of epithelium in terms of keratinization rather than to protective functions.

Adolescent↗
PubMed1991

Ocular cicatricial pemphigoid occurring as a sequela of Stevens-Johnson syndrome.

Ocular cicatricial pemphigoid is a chronic scarring inflammation of the ocular mucosae that can lead to blindness. Although cicatricial pemphigoid has been classified clinically, histopathologically, and immunopathologically, no definite initiating factor or precipitating factor has been identified. In this report, we describe five cases of ocular cicatricial pemphigoid that developed following an acute episode of severe ocular inflammatory injury secondary to Stevens-Johnson syndrome. The time lag between the onset of Stevens-Johnson syndrome and cicatricial pemphigoid ranged from a few months to 31 years. All five patients had linear immune deposits characteristic of cicatricial pemphigoid along the basement membrane zone of mucosal biopsy specimens as detected by either direct immunofluorescence microscopy or direct immunoperoxidase staining. In two patients whose serum was tested, a Western blot assay taken of keratinocyte antigens that had undergone electrophoresis reacted with the serum and identified a 120-kd epidermal antigen detected by the IgG class antibodies. All five patients were treated with systemic immunosuppressive therapy for cicatricial pemphigoid, and we obtained objective responses. Severe ocular mucosal injury such as that which occurs in Stevens-Johnson syndrome may be a precipitating factor in the development of ocular cicatricial pemphigoid.

Adult↗
PubMed1991

Proliferating cells in psoriatic dermis are comprised primarily of T cells, endothelial cells, and factor XIIIa+ perivascular dendritic cells.

Determination of the cell types proliferating in the dermis of patients with psoriasis should identify those cells experiencing activation or responding to growth factors in the psoriatic dermal milieu. Toward that end, sections of formalin-fixed biopsies obtained from 3H-deoxyuridine (3H-dU)-injected skin of eight psoriatic patients were immunostained, followed by autoradiography. Proliferating dermal cells exhibit silver grains from tritium emissions. The identity of the proliferating cells could then be determined by simultaneous visualization with antibodies specific for various cell types. UCHL1+ (CD45RO+) T cells (recall antigen-reactive helper T-cell subset) constituted 36.6 +/- 3.1% (mean +/- SEM, n = 6) of the proliferating dermal cells in involved skin, whereas Leu 18+ (CD45RA+) T cells (recall antigen naive T-cell subsets) comprised only 8.7 +/- 1.5% (n = 6). The Factor XIIIa+ dermal perivascular dendritic cell subset (24.9 +/- 1.5% of proliferating dermal cells, n = 6) and Factor VIII+ endothelial cells (23.0 +/- 2.3%, n = 6) represented the two other major proliferating populations in lesional psoriatic dermis. Differentiated tissue macrophages, identified by phase microscopy as melanophages or by immunostaining with antibodies to Leu M1 (CD15) or myeloid histiocyte antigen, comprised less than 5% of the proliferating population in either skin type. In addition to calculating the relative proportions of these cells to each other as percent, we also determined the density of cells, in cells/mm2 of tissue. The density of proliferating cells within these populations was increased in involved versus uninvolved skin: UCHL1+, 9.0 +/- 1.7 cells/mm2 versus 1.8 +/- 0.6 cells/mm2, p less than 0.01; Factor XIIIa+, 6.0 +/- 0.7 cells/mm2 versus 1.5 +/- 0.5 cells/mm2, p less than 0.01; Factor VIII+, 5.5 +/- 1.4 cells/mm2 versus 0.0 cells/mm2, p less than 0.05. The presence of preferential active proliferation of a T-cell subset in lesional dermis suggests that activating signals specific for this subset are contained within the psoriatic dermis in vivo. The activation of recall antigen-reactive T cells may be a driving force behind the dendritic cell and endothelial cell proliferation. Alternatively, the selective proliferation and expansion of these two constitutive cell types (Factor XIIIa+ and Factor VIII+) may result in signals that promote activation of UCHL1+ (CD45RO+) T cells.

Cell Division↗
PubMed1991

Concurrent eosinophilic fasciitis and cutaneous T-cell lymphoma. Eosinophilic fasciitis as a paraneoplastic syndrome of T-cell malignant neoplasms?

Eosinophilic fasciitis has been reported to precede hematologic malignant neoplasms such as myelomonocytic leukemia, lymphocytic leukemia, and Hodgkin's lymphoma. In this case study, eosinophilic fasciitis occurred concurrently with cutaneous T-cell lymphoma (mycosis fungoides). The clinical diagnosis of eosinophilic fasciitis was based on painful sclerodermatous lesions on the extremities and trunk without acrosclerosis. There was histologic confirmation with edema and lymphocytic inflammation in the superficial muscular fascia and dermis. Deposition of immune reactants was found in the fascia and dermis. In addition, peripheral eosinophilia and circulating immune complexes were detected. The diagnosis of cutaneous T-cell lymphoma (mycosis fungoides) was based on extensive erythematous cutaneous plaques, dermal and epidermal lymphocytic atypia, loss of pan-T-cell immunologic markers, and a cutaneous lesional T-cell receptor beta-chain rearrangement by Southern blot analysis. Eosinophilic fasciitis may occur as a paraneoplastic syndrome associated with hematologic malignant neoplasms, including mycosis fungoides. Cytokines or lymphokines released by activated immunocytes, either malignant leukocytes or normal leukocytes reacting to malignant cells, may be responsible for the eosinophilia and sclerosis seen in these associated hematologic malignant neoplasms.

Aged↗
PubMed1990

Fluconazole compared with amphotericin B plus flucytosine for cryptococcal meningitis in AIDS. A randomized trial.

OBJECTIVE: To compare the efficacy of fluconazole with amphotericin B plus flucytosine in the treatment of cryptococcal meningitis. DESIGN: Patients were randomly assigned to oral fluconazole, 400 mg/d, for 10 weeks or to amphotericin B, 0.7 mg/kg body weight daily for 1 week, then three times weekly for 9 weeks combined with flucytosine, 150 mg/kg d, in four divided doses. SETTING: Los Angeles County-University of Southern California Medical Center. PATIENTS: Between 15 February and 7 December 1988, 42 patients had evidence of their first episode of cryptococcal meningitis, of whom 21 participated in the trial. All patients enrolled were men with the acquired immunodeficiency syndrome (AIDS) except one woman who was receiving prednisone therapy and was excluded from the final analysis. RESULTS: Of 14 patients with AIDS assigned to fluconazole, 8 (57%; 95% CI, 29% to 82%) failed; none of the 6 patients with AIDS failed who were assigned to amphotericin B plus flucytosine therapy (0%; CI, 0% to 46%) (Fisher exact test, P = 0.04). The mean duration of positive cerebrospinal fluid cultures was 40.6 +/- 5.4 days in patients receiving fluconazole and 15.6 +/- 6.6 days in patients receiving amphotericin B plus flucytosine (Mann-Whitney test, P = 0.02). Overall, 4 patients assigned to fluconazole therapy died whereas no patient assigned to amphotericin B plus flucytosine therapy died (Fisher exact test, P = 0.27). CONCLUSION: Amphotericin B used in combination with flucytosine has superior mycologic and clinical efficacy compared with fluconazole for the treatment of cryptococcal meningitis in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1990

IL-1 activity is reduced in psoriatic skin. Decreased IL-1 alpha and increased nonfunctional IL-1 beta.

IL-1 may influence or be influenced by a number of abnormalities present in psoriasis; including keratinocyte proliferation, eicosanoid production, fibroblast activation, endothelial cell adhesiveness, T cell infiltration and activation, cyclic nucleotide metabolism, and transmembrane signal transduction mechanisms. We assessed IL-1 regulation in normal, uninvolved, and involved skin of psoriatic patients using immunofluorescence microscopy, a sensitive ELISA method to quantitate immunoreactive IL-1 beta and IL-1 alpha protein levels, the thymocyte proliferation costimulation assay, costimulation of the LBRM.33 IL-1-sensitive cell line, and Northern blotting of cellular RNA to quantitate IL-1 alpha and beta mRNA. IL-1 beta was easily detectable by immunofluorescence microscopy and found to be localized predominantly in epidermal keratinocytes, whereas IL-1 alpha was not detectable with this method. Immunoreactive IL-1 beta was found to be elevated in cytosolic extracts derived from involved psoriatic keratomes relative to keratomes of normal skin. The elevated IL-1 beta protein was accompanied by elevated levels of IL-1 beta mRNA in psoriatic skin relative to normal skin. In contrast, immunoreactive IL-1 alpha levels were markedly reduced in lesional psoriatic skin. In functional assays using both the thymocyte proliferation assay and the LBRM.33 cell line, IL-1 activity from psoriatic involved skin keratomes was markedly reduced relative to that of uninvolved psoriatic keratomes and normal skin. All activity of both normal and psoriatic skin was attributable to IL-1 alpha. The elevated IL-1 beta immunoreactive protein present in psoriatic skin was found to be functionally inactive in these assays. The inactivity of the IL-1 beta was not due to an artifact of the cytosolic method of preparation because IL-1 beta released by psoriatic skin into the media was also nonfunctional. This was in keeping with the demonstration that the IL-1 beta was nonfunctional despite existing as a processed molecule. Taken together, these data demonstrate uncoordinated regulation of IL-1 alpha and Il-1 beta in psoriasis. The profound and complex changes in this system suggest IL-1 dysregulation may be integrally involved in the inflammatory, biochemical, and proliferative processes involved in the pathophysiology of psoriasis.

Biological Assay↗
PubMed1990

Cicatricial pemphigoid. Identification of two distinct sets of epidermal antigens by IgA and IgG class circulating autoantibodies.

A patient with severe cicatricial pemphigoid demonstrated both in vivo bound and circulating anti-basement membrane zone antibodies of the IgA and IgG classes. Complement component 3 (C3) was also deposited in the basement membrane zone of lesional skin as well as in normal-appearing buccal mucosa of the patient. However, C1q was absent, while granular deposits of two factors of the alternative complement activating pathway, properdin and properdin factor B, were present only in the basement membrane zone of lesional skin, but not in normal buccal mucosa. Deposition of alternative complement pathway reactants in the lesion suggests that complement activation by IgA was associated with lesion development. Western blot analysis of the patient's serum on electrophoresed cultured keratinocyte antigens identified two distinct sets of epidermal antigens. While IgG bound antigens of 230, 205, 140, and 90 kd, the patient's IgA antibodies bound a distinct set of antigens, 180 and 130 kd. The potential pathogenic role of IgA in cicatricial pemphigoid is discussed.

Aged↗
PubMed1990

Oral cyclosporine for the treatment of alopecia areata. A clinical and immunohistochemical analysis.

Cyclosporine inhibits the activation of helper T cells that may be pathogenic in alopecia areata. Therefore we treated six patients with alopecia areata (five men, one woman) with oral cyclosporine, 6 mg/kg/day for 12 weeks. Three patients had alopecia universalis, one had alopecia totalis, and two had patchy alopecia areata of the scalp. Hair regrowth in the scalp of all patients occurred within the second and fourth weeks of therapy, followed by hair regrowth of the face and chest (in the male patients), pubic area, extremities, and axillae. Overall, the site of best response was the scalp. Cosmetically acceptable terminal hair regrowth on the scalp occurred in three of six patients. Significant hair loss, however, occurred in all patients within 3 months of discontinuation of cyclosporine treatment. Clinical response correlated with changes in immune cell infiltration of the hair follicles. The number of leukocytes per hair follicle was quantified in transverse scalp biopsy sections stained with a panel of monoclonal antibodies. The degree of terminal hair regrowth correlated significantly with decreases in follicular epithelial human lymphocyte antigen-DR and intercellular adhesion molecule-1 expression, T cells, helper/inducer (CD4) T cells, suppressor/cytotoxic (CD8) T cells and Langerhans cells (CD1+DR+) from the hair follicles during cyclosporine therapy. A significant decrease in the CD4/CD8 ratio occurred early in the course of treatment and was maintained throughout the therapy. This decrease suggests that cyclosporine not only cleared immune cells from the hair follicles but also altered the balance of regulatory lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1990

Oral manifestations of linear IgA disease.

A case of linear IgA disease with prominent oral lesions is presented. Oral manifestations in linear IgA disease have been reported as minor clinical presentations. In our patient the oral manifestations predominated and were the only clinical manifestations for 5 years before the skin lesions appeared. Linear IgA disease should be included in the differential diagnosis of bullous dermatoses with oral lesions.

Aged↗
PubMed1990

Koebnerization as a cutaneous manifestation of immune complex-mediated vasculitis.

Two unusual examples of the cutaneous manifestations of vasculitis are presented. In both cases lesions occurred on previously traumatized skin and on normal skin of the dependent areas. Lesional skin biopsy specimens obtained from the koebnerized sites and from the other dependent sites revealed evidence of vascular injury in both patients. A diagnosis of leukocytoclastic vasculitis was made in one patient and pityriasis lichenoides et varioliformis acuta in the other. Direct immunofluorescence microscopy of lesional skin specimens from both patients demonstrated dermal vascular immune deposits. Raji cell assay detected a significant elevation of circulating immune complexes in the serum of both patients. Neither koebnerizing leukocytoclastic vasculitis nor koebnerizing pityriasis lichenoides et varioliformis acuta has been reported previously.

Adult↗
PubMed1990

Effects of cyclosporine on immunologic mechanisms in psoriasis.

A major impetus for further investigation of cellular immunologic mechanisms in psoriasis has been the discovery that cyclosporine, a potent immunosuppressive, is highly effective in the treatment of psoriasis. Cyclosporine has significant inhibitory effects on the ability of T cells to become activated. However, a direct activity of this drug on human keratinocyte signal transduction or growth has been difficult to demonstrate at relevant concentrations. Nevertheless, treatment of psoriasis or of 12-O-tetradecanoyl phorbol-13-acetate-treated murine skin with cyclosporine does reverse many epidermal abnormalities that are common to these two systems. This suggests that the compound exerts an indirect effect on epidermal keratinocytes in vivo, perhaps through immunocyte inhibition. During treatment of psoriasis patients, cyclosporine therapy resulted in selective changes in the numbers and functions of certain antigen-presenting cell subsets (which were distinct from Langerhans cells) and T-cell subsets. These changes were accompanied by indirect evidence of decreased T-cell lymphokine release. Lesional activity of cyclosporine-treated psoriasis patients was closely correlated with the degree of T-cell activation caused by antigen-presenting cells. Cyclosporine inhibition of lymphokine or cytokine release may result in decreased recruitment of non-Langerhans antigen-presenting cells into the epidermis and thus decreased immunoreactivity in the lesion.

Cyclosporins↗
PubMed1990

Determining nursing retention strategy in a large public teaching hospital.

In 1988, the Los Angeles County University of Southern California Medical Center (LAC USC) surveyed 1,102 RNs (75% of its total RN population) to determine factors critical to nursing retention. The Nursing Retention Survey required participants to rank 46 retention factors related to compensation benefits, work environment, amount and type of work, work relationships, availability of support services, management practices, and opportunities for professional growth. This article reports survey responses for the ten most significant and ten least significant retention factors. Survey findings, which guided LAC USC in designing nursing retention strategies, show that RNs who stated that they would leave their jobs were consistently less satisfied with all the top-ranking important elements than those who would stay.

Attitude of Health Personnel↗
PubMed1990

Use of the MANTRELS score in childhood appendicitis: a prospective study of 187 children with abdominal pain.

We report an evaluation of the MANTRELS clinical score in predicting appendicitis in a prospectively studied pediatric population presenting with abdominal pain. One hundred eighty-nine independent episodes from 187 children 2 to 17 years old were studied. For the groups as a whole and for the individual groups less than 16 years old, the score failed to satisfactorily discriminate those with appendicitis from those without. Had the MANTRELS score been used to determine observation and laparotomy in our patients, 21 additional patients would have been unnecessarily hospitalized, and 16 would have been subjected to unnecessary laparotomies. One patient would have received appropriate intervention earlier. In the 40 children 16 and 17 years old, the MANTRELS score adequately distinguished the two groups. A seven-variable discriminant function, derived from stepwise discriminant analysis, performed slightly better but showed essentially the same findings as the MANTRELS score. We believe the MANTRELS score failed to predict appendicitis in younger children because it does not contain variables that allow for separation of appendicitis from the numerous other conditions mimicking it in the pediatric population. The clinician remains the best judge of the acute abdomen in the pediatric age group.

Abdominal Pain↗
PubMed1990

An incentive program to increase revenue in a public hospital.

Using financial reward systems to enhance revenue generation or promote cost savings has been more difficult in public than in private hospitals. The program at the Los Angeles County-University of Southern California Medical Center has demonstrated, however, that it can be done.

Cost Control↗
PubMed1990

UM4D4+ (CDw60) T cells are compartmentalized into psoriatic skin and release lymphokines that induce a keratinocyte phenotype expressed in psoriatic lesions.

UM4D4 (CDw60), the surface molecule of a novel antigen-independent T-cell activation pathway, was found to be highly expressed on lesional psoriatic T cells. To examine whether UM4D4 represents a T-cell activation pathway for psoriatic T cells, a T-cell line was initiated from an acute skin lesion and cloned by limiting dilution. Clonality was verified by analysis of T-cell receptor gene rearrangement. All T-cell clones tested, whether CD4+2H4+CD8-, CD4+2H4-CD8-, or CD4-CD8+CD11b-, expressed UM4D4 and were activated by the monoclonal antibody anti-UM4D4. Lesional psoriatic T-cell clones were heterogeneous in the degree of anti-UM4D4-induced proliferation and in their production of IL-2 and gamma-interferon. Lymphokines released by anti-UM4D4 activation were capable of inducing ICAM-1 and HLA-DR expression on cultured normal keratinocytes. Thus, the high expression of UM4D4 on T-cells in psoriatic skin provides an alternative mechanism for T-cell activation that may be operative in the psoriatic lesional milieu. Indeed, activation of lesional T-cells through the UM4D4 molecule resulted in release of lymphokines that directly induced keratinocytes to express a phenotype displayed in psoriatic skin lesions.

Antigens, CD↗