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L S Chan

Publications and source records attributed to L S Chan.

At least 91 records · Page 5Linked to original sources
PubMed1995

Canine bullous pemphigoid (BP): identification of the 180-kd canine BP antigen by circulating autoantibodies.

Human bullous pemphigoid (BP) is an immune-mediated blistering disease characterized by autoantibodies against BP antigens (230/180 kd), which are constitutive glycoproteins of hemidesmosomes found in basal keratinocytes. Blistering diseases similar to human BP have been reported in dogs. IgG deposits at the basement membrane zone (BMZ) are a common feature of canine BP. Although circulating anti-BMZ IgG autoantibodies have been demonstrated in some cases of canine BP, the specific skin protein targeted by these autoantibodies has not been identified. In this study, we characterized the antigenic target of the autoantibodies in the serum from a 3-year-old castrated male Pit Bull Terrier with BP. Direct immunofluorescence of the patient's skin demonstrated IgG deposits at the dermal-epidermal junction. Indirect immunofluorescence demonstrated autoantibodies in the patient's serum that stained the epidermal roof of salt-split canine skin and left the dermal floor unstained. These serum autoantibodies did not stain normal intact dog skin but labeled intact bovine tongue. Direct immunoelectron microscopy of the dog's skin revealed IgG deposits within the hemidesmosomes of the basal keratinocytes. Western immunoblotting experiments showed that canine keratinocytes express both the 230-kd and 180-kd bullous pemphigoid antigens, and the autoantibodies from the patient's serum recognized the 180-kd bullous pemphigoid antigen in proteins extracted from canine and human keratinocytes. Canine BP has many parallel features with human BP including similar immune deposition of IgG within hemidesmosomes and a hemidesmosome-associated 180-kd glycoprotein target for circulating autoantibodies.

Animals↗
PubMed1995

Woringer-Kolopp disease (localized pagetoid reticulosis) or unilesional mycosis fungoides? An analysis of eight cases with benign disease.

BACKGROUND: The controversial nosology of Woringer-Kolopp disease (localized pagetoid reticulosis, unilesional mycosis fungoides) is being clarified by the systematic immunophenotypic and immunogenetic examination of infiltrating lesional T lymphocytes. The clinical course and immunohistochemical characteristics of eight cases of Woringer-Kolopp disease are described. OBSERVATIONS: Lesions measured 0.8 x 0.5 to 16.0 x 15.0 cm. Histologically, all cases resembled mycosis fungoides-type cutaneous T-cell lymphoma and phenotypic analysis supported their designation as an epidermotropic T-cell process. Phenotypic aberrancy was not noted on immunohistochemical analysis of paraffin-embedded tissue. Three of four patients with available fresh-frozen tissue specimens demonstrated reduced or absent expression of CD7 (Leu-9) and/or Leu-8, while loss of the pan-T-cell markers CD2, CD3, and CD5 was not observed. Only in half these patients was a lesional predominance of CD4+ T-cells revealed. Germline DNA was detected in a lesional skin specimen obtained from one patient tested for T-cell receptor gene rearrangements. After treatment, the observation of disease-free periods ranging from 18 months to 17 years (mean, 5.9 years) reinforces the view that Woringer-Kolopp disease is a focal pathologic event with a favorable prognosis. No patient experienced a local recurrence or distant spread of the disease. CONCLUSION: This and previous studies suggest that Woringer-Kolopp disease is a unique, benign unilesional T-cell lymphoproliferative process with certain histologic and phenotypic similarities to both early epidemotropic mycosis fungoides-type cutaneous T-cell lymphoma and other T-cell lymphoproliferations.

Adult↗
PubMed1994

Identification of the epitopes on human type VII collagen for monoclonal antibodies LH 7.2 and clone I, 185.

Type VII collagen is the major component of anchoring fibrils, structures in human skin that mediate the adherence of the epidermis to the underlying dermis. Dystrophic forms of epidermolysis bullosa, a group of inherited mechanobullous disorders of the skin, are linked to the type VII collagen gene. Several mutations in the recessive form of this inherited disorder have been delineated. In this study, we mapped the epitopes of two commercially available monoclonal antibodies (clone I, 185 and LH 7.2) within the amino-terminal, non-collagenous domain of type VII (anchoring fibril) collagen. The precise localizations of the epitopes for these two monoclonal antibodies which are widely used to diagnose dystrophic epidermolysis bullosa, will be useful for the confirmation of gene mutations at the protein level.

Antibodies, Monoclonal↗
PubMed1994

A novel 105-kDa lamina lucida autoantigen: association with bullous pemphigoid.

Several cases have been reported of patients with immunemediated subepidermal blistering disorders whose autoantibodies react to antigens present on both the dermal and epidermal side of 1 M NaCl-split skin. In this report, we identify, localize, and characterize the basement membrane zone antigen corresponding to the dermal staining in a patient whose serum stains both the dermal and epidermal side of 1 M NaCl-split skin. This patient's serum contains autoantibodies directed against a 105-kilodalton(kDa) dermal antigen and the 230-kDa epidermal (bullous pemphigoid) antigen. This novel 105-kDa protein was previously identified as the sole antigen in another patient with a unique bullous disease whose autoantibodies were directed against only the dermal side of 1 M NaCl-split skin. This 105-kDa antigen was identical by one- and two-dimensional immunoblot analysis in these two patients. By immunoblot analysis, autoantibodies from our patient labeled a 105-kDa protein within various extracts of human skin basement membrane. Immunoblot analyses using epitope-selected autoantibodies directed against the 105-kDa protein demonstrated that this antigen is independent and distinct from other known basement membrane antigens. The 105-kDa antigen is an extracellular matrix component of the basement membrane, which is synthesized and secreted by both keratinocytes and fibroblasts. Identical electrophoretic migration of cellular and secreted forms of the protein suggested there is no major post-translational modification of the protein. Immunomapping of normal human skin fractured through the dermal-epidermal junction by incubation in 1 M NaCl or by suction blistering demonstrated that the location of the 105-kDa antigen within the basement membrane zone is between the bullous pemphigoid antigens and two other lamina lucida components, laminin and nicein. These data demonstrate clearly that a subepidermal autoimmune bullous disease may have autoantibodies directed against two distinct components of the dermal-epidermal junction.

Aged↗
PubMed1994

High frequency of HLA-DQB1*0301 allele in patients with pure ocular cicatricial pemphigoid.

Two factors, is classification and its immunogenetics, may have contributed to an incomplete understanding of the pathogenic mechanism in the disease group commonly termed 'cicatricial pemphigoid'. We have previously demonstrated that pure ocular cicatricial pemphigoid (OCP) is a unique clinical and immunopathological entity. In an effort to better define the immunogenetic characteristics for patients with pure OCP, we performed HLA typing for the class II MHC gene HLA-DQB1*0301 allele, by amplifying genomic DNA extracted from patients with polymerase chain reaction, followed by hybridization with a sequence-specific oligonucleotide probe on dot-blotted and Southern-blotted amplified DNA samples. Ninety percent (9/10) of patients with pure OCP had the DQB1*0301 allele, in contrast to 52% (17/33) of normal individuals who had the DQB1*0301 allele. The high frequency of the HLA-DQB1*0301 allele in patients with pure OCP may point to a distinct immunogenetic pattern and possibly a distinct pathomechanism for the disease.

Alleles↗
PubMed1994

A novel immune-mediated subepidermal bullous dermatosis characterized by IgG autoantibodies to a lower lamina lucida component.

BACKGROUND: Immune-mediated subepidermal bullous dermatoses characterized by in vivo-bound linear IgG deposition at the cutaneous basement membrane zone include bullous pemphigoid, ocular cicatricial pemphigoid, anti-bullous pemphigoid antigen mucosal pemphigoid, anti-epiligrim mucosal pemphigoid, epidermolysis bullosa acquisita, and the bullous eruption of systemic lupus erythematosus. In this article, we describe a novel IgG-mediated bullous dermatosis. OBSERVATIONS: Clinically, a unique nonscarring dermatosis was characterized by the sudden onset of extensive bullae and erosions on mucous membrane and skin, resembling toxic epidermal necrolysis or pemphigus vulgaris. Histologically, the patient's skin lesion demonstrated neutrophilic papillary dermal infiltration and subepidermal blister formation, resembling dermatitis herpetiformis. Immunopathologically, there was linear IgG and C3 deposition at the skin basement membrane zone. The patient responded well to prednisone and azathioprine immunosuppression and has achieved a lasting remission without further therapy. Further immunologic investigations revealed that this unique dermatosis is distinct from all other known IgG-mediated subepidermal bullous dermatoses. CONCLUSIONS: This novel deep lamina lucida pemphigoid can be distinctly termed anti-p105 pemphigoid on the basis of antigenic specificity of the autoantibodies. Although this novel dermatosis resembles toxic epidermal necrolysis clinically, prudent use of diagnostic immunofluorescence studies can clearly delineate its immunologic nature. Prompt recognition of this unique dermatosis and timely initiation of appropriate immunosuppressive therapy could be life-saving for those patients suffering from this dermatosis.

Autoantibodies↗
PubMed1993

Immune-mediated subepithelial blistering diseases of mucous membranes. Pure ocular cicatricial pemphigoid is a unique clinical and immunopathological entity distinct from bullous pemphigoid and other subsets identified by antigenic specificity of autoantibodies.

BACKGROUND AND DESIGN: There is much confusion in the clinical classification of immune-mediated subepithelial blistering diseases of mucous membranes. We conducted a 6-year comprehensive study to better classify this heterogeneous disease group. Indirect immunofluorescence was performed on a salt-split-skin substrate to detect circulating antibasement membrane antibodies (n = 47). Serologic reactivity against cultured keratinocyte antigens was examined by immunoblots (n = 38) and immunoprecipitation (n = 15). The results were correlated with the clinical features and direct immunofluorescence data of the entire patient group (n = 87) without preassignment of clinical diagnoses. chi 2 Statistical analyses compared these results with those of the classic bullous pemphigoid group (n = 36). RESULTS: When compared with the bullous pemphigoid patients, a subset of patients with combined oral mucosal and skin lesions demonstrated marked similarity in direct and indirect immunofluorescence findings and in serologic reactivity to bullous pemphigoid antigens. By contrast, a subset of patients with only ocular lesions exhibited significantly lower in vivo deposits of IgG and C3, higher deposits of fibrin, virtual absence of circulating antibodies, and negative serologic reactivity to bullous pemphigoid antigens. CONCLUSIONS: Ocular patients without skin or mouth lesions, in particular those with negative indirect immunofluorescence, should be distinctively classified as ocular cicatricial pemphigoid, a unique clinical and immunopathologic entity. Patients with mucous membrane involvement who also demonstrate skin lesions and antibodies to the root of salt-split-skin substrate should be classified as anti-BP Ag mucosal pemphigoid, even though they may exhibit severe oral and/or ocular diseases. The remaining mucous membrane patients are heterogeneous. Some can be classified on the basis of autoantibodies to other basement membrane determinants, or if serum autoantibody negative, on the basis of clinical features (ie, pure oral mucosal pemphigoid or overlapping mucosal involvement).

Autoantibodies↗
PubMed1993

How much information is lost during processing? A case study of pediatric emergency department records.

This is a retrospective study determining the completeness and accuracy of processed information of emergency department (ED) records of a busy urban children's hospital. The method of study was based on comparing computer processed information with that in the patient's medical chart. A total of 457 ED visits from April 5 to April 25 of 1992 were audited. Accuracy was found to differ with the type of data element and the setting. Among admissions, admitting diagnoses coding had the highest error rate (53.1%), followed by age (33.2%), admitting time (31.0%), and admitting ward (12.5%). Among discharges, time in had the highest error rate (76.0%), followed by area where seen (56.9%), physician name (48.4%), time out (37.8%), age (33.3%), mode of arrival (26.2%), diagnosis (20.1%), patient's condition (17.3%), and triage level (10.7%). Despite advances in computerized information systems, error rates of processed information remain unacceptably high. Future information systems should be interactive, recording rather than processing information flows between the provider and the patient.

Child↗
PubMed1993

Pemphigoid vegetans represents a bullous pemphigoid variant. Patient's IgG autoantibodies identify the major bullous pemphigoid antigen.

Pemphigoid vegetans is a rare disease; only four cases have been reported. The relationship of pemphigoid vegetans to bullous pemphigoid is not completely defined. We describe a case in a 77-year-old woman who had multiple well-circumscribed, erythematous, erosive, and vegetating plaques in the axillae and inframammary areas and in the neck. Microscopic examination revealed epidermal hyperplasia, dermoepidermal junctional separation, and prominent dermal eosinophilia. In the perilesional skin IgG was deposited linearly at the basement membrane zone. In addition, our patient's IgG autoantibodies, primarily the IgG4 subclass, reacted with the epidermal side of salt-split normal human skin and with the 230 kd major bullous pemphigoid antigen. We conclude that pemphigoid vegetans is best classified as a bullous pemphigoid variant.

Aged↗
PubMed1993

Identification and partial characterization of a novel 105-kDalton lower lamina lucida autoantigen associated with a novel immune-mediated subepidermal blistering disease.

Certain skin basement membrane components, such as bullous pemphigoid antigens and epidermolysis bullosa acquisita antigen, were discovered as a result of an autoimmune reaction. In this report, we describe a unique lamina lucida determinant associated with a novel immune-mediated subepidermal bullous dermatosis. This unique bullous dermatosis resembled severe toxic epidermal necrolysis clinically. The histologic findings resemble dermatitis herpetiformis. Direct immunofluorescence microscopy detected linear immunoglobulin G (IgG) and C3 deposition at the cutaneous basement membrane zone of lesional and perilesional skin. Direct and indirect immunoelectron microscopy localized the IgG deposits to the lowest portion of the lamina lucida. The patient's autoantibodies, belonging to the IgG1 subclass, labeled basement membrane zone of normal intact human skin, oral mucosa, and conjunctiva, and localized to the dermal side of salt-split normal adult and neonatal human skin, but failed to react with human fetal skin up to 142 gestational days. The patient's autoantibodies failed to react with bullous pemphigoid antigens or epidermolysis bullosa acquisita antigen (type VII collagen) by immunoblotting. Instead, the patient's autoantibodies unequivocally labeled a 105-kilodalton (kD) protein in cellular extracts and conditioned media of human cultured keratinocytes and dermal fibroblasts. The titer of the patient's antibody against the cutaneous basement membrane zone and the intensity of the antibody reactivity against the 105-kD protein paralleled the patient's disease activity. Thus, this 105-kD lower lamina lucida protein represents a novel autoantigen and this patient's disease represents a novel autoantigen and this patient's disease represents a deep lamina lucida pemphigoid, distinguishable from all other known autoimmune bullous dermatoses.

Autoantigens↗
PubMed1992

Birth prevalence of Down syndrome in a predominantly Latino population: a 15-year study.

The birth prevalence of Down syndrome (DS), although decreasing in parts of the world, is not known in many specific subpopulations. The rate of DS for live births was determined for a 15-year period (1974-1988) at the Los Angeles County-University of Southern California Medical Center, which is a large public hospital serving a predominantly Latino population. DS was ascertained primarily by clinical monitoring of newborn infants. The overall rate of DS was 1.60/1,000 live births and had minimal fluctuation throughout the 15 years. The rate of DS for Latino births was 1.69/1,000 live births, 1.67 when adjusted for maternal age, and 1.75 when corrected for prenatal diagnosis. The high rate of DS in the Latino population was associated with advanced maternal ages and increased maternal-age specific rates for DS, especially in the age ranges of 30 to 34 and 40 to 44 years, when compared with other studies.

Adolescent↗
PubMed1992

Elective induction versus spontaneous labor: a retrospective study of complications and outcome.

OBJECTIVE: This retrospective study was undertaken to identify whether electively induced labor places the mother or her fetus at increased risk as compared with her spontaneous labor cohort. STUDY DESIGN: This study compares the labor, delivery, and fetal outcome of 253 parturients in which labor was electively induced with 253 matched controls who began labor spontaneously. All patients were delivered at Huntington Memorial Hospital in Pasadena, California, during the calendar year 1990. The patients were between 37 and 41 weeks' gestation and had no medical or obstetric conditions necessitating induction. The cases and controls were matched for age group, parity, gestational age, and delivering obstetrician. RESULTS: Epidural anesthesia was used in 83.8% of patients in the induction group versus 55.7% in the spontaneous group. Patients with labor induced had a shorter first stage of labor. Meconium staining was found significantly more often in the spontaneous group than in the induced group (16.2% vs 6.7%). This contributed to a greater rate of neonatal consultations in the spontaneous labor group. Although cesarean section rates between the two groups were similar, nulliparous patients in the induction group with an estimated Bishop score of less than or equal to 5 had a 50% cesarean section rate. Iatrogenic prematurity was not encountered. No differences existed between the two groups with respect to intrapartum maternal complications, fetal complications, or postpartum complications. CONCLUSIONS: When compared with spontaneous labor, elective induction of labor at term does not appear to pose an increased risk to the mother or her fetus in a carefully selected patient population. However, elective induction of labor in a nulliparous patient with an unfavorable cervix should be discouraged.

Cohort Studies↗