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Biomedical subjects

A N Lin

Publications and source records attributed to A N Lin.

At least 37 records · Page 2Linked to original sources
PubMed1992

Lack of efficacy of phenytoin in recessive dystrophic epidermolysis bullosa. Epidermolysis Bullosa Study Group.

BACKGROUND: Recessive dystrophic epidermolysis bullosa is an uncommon, severely disabling, heritable disorder characterized by abnormal fragility of the skin. Open trials have suggested that phenytoin is an effective treatment, and this therapy is now widely used. METHODS: To determine the efficacy of phenytoin in the treatment of recessive dystrophic epidermolysis bullosa, we performed a randomized, double-blind, placebo-controlled, crossover trial in 36 patients. Each treatment was given for five to seven months, separated by a two-month period. We measured the total number of blisters and erosions on the entire body, the size of three plaques containing blisters and erosions, and the number of blisters and erosions in the three plaques at the beginning and end of each treatment period in each patient. RESULTS: Twenty-two patients completed both courses of therapy, seven patients completed one course, and seven patients withdrew before completing a single course. There was no significant difference in disease activity between phenytoin treatment and placebo treatment, as measured by changes in the number of blisters and erosions on the entire body (7 percent decrease vs. 6 percent increase), in the area of three designated plaques (0.4 percent decrease vs. 0.2 percent increase), or in the number of blisters and erosions in the designated plaques (12 percent decrease vs. 31 percent increase). CONCLUSIONS: Phenytoin is not an effective treatment for patients with recessive dystrophic epidermolysis bullosa.

Adolescent↗
PubMed1992

Gastrointestinal manifestations of epidermolysis bullosa. A study of 101 patients.

One hundred one patients with EB were evaluated by a combination of prospective and retrospective review, and analyzed regarding the nature, incidence, and prevalence of their gastrointestinal (GI) manifestations. Involvement of the GI tract is a well-known extracutaneous manifestation of dystrophic EB, but it also occurred in more than one-half and one-third, respectively, of those with junctional and simplex EB. Most of the serious consequences, such as esophageal strictures and microstomia, occurred in recessive dystrophic EB but were also seen, although infrequently, in the junctional and simplex forms. The majority of patients with dysphagia had an esophageal stricture, and the cervical esophagus was the most common location. The onset of dysphagia generally occurred in the first decade of life, in patients much younger than previously recognized. Diagnostic endoscopy did not reveal lesions which could not have been detected radiographically. Lower GI complaints were common, especially constipation and perianal blistering, and affected all types of EB. These complaints contributed substantially to management problems but they did not correlate with colonic pathology and appeared to reflect anal or perianal disease.

Adolescent↗
PubMed1992

Junctional epidermolysis bullosa of the larynx. Report of a case and literature review.

Epidermolysis bullosa (EB) is a group of rare inherited disorders in which minor trauma causes blister formation in the skin and mucosa, including the esophagus. Morbidity varies with the type of disease and ranges from occasional trivial skin blisters to death in infancy. Laryngeal involvement presenting as hoarseness and respiratory distress has been reported in nine patients, five of whom had junctional EB. We present the sixth case of junctional EB with laryngeal involvement, and offer guidelines for otolaryngologists and anesthesiologists caring for these fragile patients.

Child, Preschool↗
PubMed1991

Junctional epidermolysis bullosa keratinocytes in culture display adhesive, structural, and functional abnormalities.

An unusual, elongated, refractile cell morphology was observed in keratinocytes cultured from three patients with non-lethalis forms of junctional epidermolysis bullosa (JEB). To determine whether these changes might be related to altered cell adhesion, keratinocyte strains established from one patient were examined for adhesive, structural, and functional characteristics. JEB keratinocytes expressed keratin tonofilaments, as determined by staining with AE1 monoclonal antibodies and direct observation of tonofilaments by electron microscopy. JEB keratinocytes showed diminished cell-substratum adhesions, judged by interference reflection microscopy. Areas of diminished cell-substratum adhesion corresponded to F-actin-rich cell adhesions (focal adhesions) and not to cellular areas that abundantly express hemidesmosomal antigens. Analysis of cell-substratum adhesion by electron microscopy revealed extensive areas of cell-substratum separation in JEB keratinocytes that were not present in normal keratinocytes maintained in serum-free medium. Normal keratinocytes displayed numerous regions of focal contact between the ventral plasma membrane and the culture substratum, but these structures were not seen in JEB keratinocytes. Bundled actin filaments (stress fibers) were greatly diminished in expected regions of cell-substratum adhesion in JEB keratinocytes and, instead, displayed disorganized individual filaments. The growth rate of JEB keratinocytes was quite slow in culture, with a population doubling time of 2.7 d versus 1.5 d for normal keratinocytes under identical conditions. JEB keratinocytes also displayed a reduced ability to aggregate into colonies upon exposure to medium with increased extracellular calcium. JEB keratinocytes thus display adhesive, structural, and functional abnormalities that suggest this cell type may be central to the pathogenesis of junctional epidermolysis bullosa. Study of affected keratinocytes could be important to characterize associated molecular pathologies.

Actins↗
PubMed1990

Parasite-induced processes for adenosine permeation in mouse erythrocytes infected with the malarial parasite Plasmodium yoelii.

In mouse erythrocytes harbouring the malarial parasite Plasmodium yoelii, three processes contributed to inward fluxes of adenosine, one of which is attributed to the native nucleoside transporter, because of the inhibitory effects of nitrobenzylthioinosine (NBMPR). New (parasite-induced) permeation processes of low NBMPR-sensitivity were (i) saturable fluxes with preference for the D enantiomer (D-Ado) and (ii) apparently unsaturable fluxes that proceeded by a channel-like route without enantiomeric selectivity. Parasite-induced fluxes of L- and D-Ado were similarly inhibited by furosemide [IC50 (concn. causing half-maximal inhibition) 15-17 microM], whereas D-Ado fluxes in uninfected erythrocytes were 10-fold less sensitive.

Adenosine↗
PubMed1990

Phosphorylation by protein kinase C inactivates an inositol 1,4,5-trisphosphate 3-kinase purified from human platelets.

An inositol 1,4,5-trisphosphate 3-kinase purified from human platelets contains two major components, 53 and 36 kDa polypeptides. Each polypeptide expresses Ca2+/calmodulin-dependent enzymatic activity and is phosphorylated by an unidentified protein kinase in the enzyme preparation. The 36-kDa polypeptide may be further phosphorylated on serine residues by protein kinase C to a stoichiometry of 0.8 mole phosphate per mole of protein. Phosphorylation of the 36-kDa component is correlated with inhibition of the kinase activity; the inhibitory effect is dependent upon Ca2+ and phosphatidylserine/diolein and may be blocked by a selective peptide inhibitor of protein kinase C. Phosphorylation by protein kinase C decreases the Vmax of the enzyme from 160 to 28 nmol/mg/min; the Km (0.76 microM) is not altered. These data suggest that protein kinase C may negatively regulate inositol 1,4,5-trisphosphate 3-kinase activity in the human platelet.

Amino Acid Sequence↗
PubMed1990

Mupirocin-resistant Staphylococcus aureus after long-term treatment of patients with epidermolysis bullosa.

In a long-term, open study, 47 patients with epidermolysis bullosa were treated with topical 2% mupirocin (Bactroban) ointment to decrease bacterial infection and promote wound healing. This antibiotic is effective against gram-positive but not gram-negative organisms. No significant adverse effects were noted, although some patients have been treated for more than 4 years. We sought evidence in this patient population for the appearance of bacterial strains with decreased sensitivity to mupirocin. In five patients cultures from nonhealing wounds revealed Staphylococcus aureus resistance to mupirocin. Four of these patients were given oral antibiotics to which S. aureus was sensitive; they improved clinically, and cultures of their wounds became negative for pathogens.

Adult↗
PubMed1989

Nonmelanoma skin cancers in the elderly.

This article discusses the relationship between aging and development of nonmelanoma skin cancer. Possible age-related risk factors for development of such cancers are cumulative exposure to ultraviolet irradiation from the sun, decreased DNA repair capacity, decreased immunosurveillance, reduced melanocyte density, and altered dermal matrix. Clinical features of basal-cell carcinoma, squamous-cell carcinoma, and keratoacanthoma are discussed.

Aged↗
PubMed1988

Sulfur revisited.

Sulfur is a time-honored therapeutic agent useful in a variety of dermatologic disorders. Its keratolytic action is due to formation of hydrogen sulfide through a reaction that depends upon direct interaction between sulfur particles and keratinocytes. The smaller the particle size, the greater the degree of such interaction and the greater the therapeutic efficacy. When applied topically, sulfur induces various histologic changes, including hyperkeratosis, acanthosis, and dilatation of dermal vasculature. One study showed that sulfur was comedogenic when applied onto human and rabbit skin, findings that were not reproduced in other studies. About 1% of topically applied sulfur is systemically absorbed. Adverse effects from topically applied sulfur are uncommon and are mainly limited to the skin. In infants, however, fatal outcome after extensive application has been reported.

Acne Vulgaris↗
PubMed1988

Wound healing and epidermolysis bullosa.

Wound healing is reviewed in the context of the unique problems of the chronic ulcerating skin lesions associated with epidermolysis bullosa. Management approaches, including treatment of erosions with epidermal autografts, are considered.

Adolescent↗
PubMed1987

Location of the redox-active thiols of ribonucleotide reductase: sequence similarity between the Escherichia coli and Lactobacillus leichmannii enzymes.

The redox-active thiols of Escherichia coli ribonucleoside diphosphate reductase and of Lactobacillus leichmannii ribonucleoside triphosphate reductase have been located by a procedure involving (1) prereduction of enzyme with dithiothreitol, (2) specific oxidation of the redox-active thiols by treatment with substrate in the absence of exogenous reductant, (3) alkylation of other thiols with iodoacetamide, and (4) reduction of the disulfides with dithiothreitol and alkylation with [1-14C]iodoacetamide. The dithiothreitol-reduced E. coli B1 subunit is able to convert 3 equiv of CDP to dCDP and is labeled with 5.4 equiv of 14C. Sequencing of tryptic peptides shows that 2.8 equiv of 14C is on cysteines-752 and -757 at the C-terminus of B1, while 1.0-1.5 equiv of 14C is on cysteines-222 and -227. It thus appears that two sets of redox-active dithiols are involved in substrate reduction. The L. leichmannii reductase is able to convert 1.1 equiv of CTP to dCTP and is labeled with 2.1 equiv of 14C. Sequencing of tryptic peptides shows that 1.4 equiv of 14C is located on the two cysteines of C-E-G-G-A-C-P-I-K. This peptide shows remarkable and unexpected similarity to the thiol-containing region of the C-terminal peptide of E. coli B1, C-E-S-G-A-C-K-I.

Alkylation↗
PubMed1987

Treatment of junctional epidermolysis bullosa with epidermal autografts.

We have successfully treated chronic facial erosions in three boys with junctional epidermolysis bullosa. In each patient, keratinocytes were harvested from the roof of suction blisters created on clinically uninvolved skin. They were grown in tissue culture on collagen sponges and grafted onto facial erosions that were previously treated with 2% mupirocin ointment. This experimental antibiotic ointment has proved efficacy in eradicating cutaneous pathogens such as Staphylococcus aureus from chronic wounds. In two patients, complete reepithelialization was achieved over 7 and 10 months, respectively, and partial reepithelialization occurred in another patient in whom treatment is ongoing. Epidermal autografts are a promising means for improving function and appearance in eroded skin caused by junctional epidermolysis bullosa.

Adolescent↗
PubMed1987

Abnormalities of plasma and erythrocyte essential fatty acid composition in epidermolysis bullosa: influence of treatment with diphenylhydantoin.

The fatty acid composition of plasma and erythrocyte phospholipids was determined in children with various subtypes of epidermolysis bullosa (EB) and in their parents. Patients with recessive dystrophic, dominant dystrophic, simplex, or junctional forms of EB had a higher percentage composition of arachidonic acid in plasma and/or erythrocyte phospholipids compared to age-matched controls. Epidermolysis bullosa patients treated with diphenylhydantoin had lower levels of arachidonic acid in plasma and erythrocyte phospholipids than did untreated EB patients. Parents of children with the recessive dystrophic or junctional EB subtypes had higher linoleic and arachidonic acids in plasma and erythrocyte phospholipids than did controls. Plasma and erythrocyte total lipids were within the normal range in children with EB. Plasma zinc was also normal but plasma copper was elevated in children with recessive dystrophic EB. We conclude that higher arachidonic acid in plasma and erythrocytes may be related to the pathology of EB.

Adult↗
PubMed1986

Skin cancer in the elderly.

This article discusses the relation between aging and development of nonmelanoma skin cancer. Possible age-related risk factors for development of such cancers are cumulative exposure to ultraviolet irradiation from the sun, decreased DNA repair capacity, decreased immunosurveillance, reduced melanocyte density, and altered dermal matrix. Clinical features of basal-cell carcinoma, squamous-cell carcinoma, and keratoacanthoma are discussed.

Aged↗
PubMed1986

Familial lichen planus.

We observed the simultaneous occurrence of generalized lichen planus in a woman and her mother. Both patients improved after therapy with topical steroid and salicylic acid ointment. Of the eighty-one cases of familial lichen planus previously reported, the vast majority (89 percent) occurred in blood relatives. The intervals of onset between familial cases were long, ranging from six weeks to thirty years (mean 73.4 months). These observations suggest that familial lichen planus may result from genetic predisposition, rather than from an infectious cause.

Adult↗
PubMed1985

Tar revisited.

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Animals↗