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Biomedical subjects

W L Hoffman

Publications and source records attributed to W L Hoffman.

At least 19 recordsLinked to original sources
PubMed1997

Cryogen spray cooling during Nd:YAG laser treatment of hemangiomas. A preliminary animal model study.

BACKGROUND: Successful laser treatment of hemangiomas requires selective photothermal destruction of dilated cutaneous vessels without damaging the overlying epidermis. Delivering a short cryogen spurt, on the order of milliseconds, has been shown to result in localized cooling of the superficial skin structures during laser irradiation. OBJECTIVE: The purpose of this study was to examine the effectiveness of cryogen spray cooling (CSC) in protecting superficial tissue structures during continuous Nd:YAG laser irradiation of an in vivo model hemangioma. METHODS: The highly vascularized chicken comb was selected as the animal model for hemangiomas. The Nd:YAG laser irradiation ranged from 2.6 to 35.1 J/mm2. A feedback system utilizing infrared radiometry monitored the comb surface temperature and controlled delivery time of the cryogen spurt. When comb surface temperature during laser irradiation reached 36-42 degrees C, a 30-100 msec cryogen spurt was delivered. Animals were euthanized 1 hour to 21 days following each experiment. Gross and histologic analyses were performed. RESULTS: Nd:YAG laser irradiation resulted in deep (up to 6.1 mm) tissue photocoagulation, while CSC preserved the overlying epidermis and papillary dermis. CONCLUSION: The results demonstrate that CSC is effective in protecting the epidermis and papillary dermis, while achieving deep tissue photocoagulation during Nd:YAG laser irradiation. Further pilot studies in humans appear warranted.

Aerosols↗
PubMed1997

Photodynamic therapy of actinic keratosis with topical 5-aminolevulinic acid. A pilot dose-ranging study.

OBJECTIVE: To examine the safety and efficacy of photodynamic therapy using topical 5-aminolevulinic acid (ALA) and red light to treat actinic keratoses (AKs). DESIGN: Actinic keratoses were treated with topical ALA (concentrations of 0%, 10%, 20%, or 30%) under occlusion for 3 hours. Before photodynamic therapy, sites were examined for fluorescence. Sites were irradiated with an argon pumped dye laser (630 nm) at fluences of 10 to 150 J/cm2. SETTING: Academic medical center. PATIENTS: Forty patients with 6 clinically typical, previously untreated AKs per patient. MAIN OUTCOME MEASURE: Complete resolution and decrease in lesion area of the AK relative to baseline evaluated at weeks 1, 4, 8, and 16. RESULTS: Three hours after ALA administration, lesions showed moderate red fluorescence. Cutaneous phototoxic effects, localized erythema and edema, peaked at 72 hours. Patients experienced mild burning and stinging during light exposure. Eight weeks after a single treatment using 30% ALA, there was total clearing of 91% of lesions on the face and scalp and 45% of lesions, on the trunk and extremities. No significant differences were observed in clinical responses with treatment using 10%, 20%, or 30% ALA. All concentrations of ALA were more effective than treating AKs with vehicle and light. CONCLUSIONS: Topical photodynamic therapy with ALA is an effective treatment of typical AKs. Complete clearing of nonhypertrophic AKs can be achieved with 10%, 20%, or 30% ALA that is easily tolerated by the patient. Lesions on the face and scalp are more effectively treated than lesions on the trunk and extremities. Hypertrophic AKs did not respond effectively.

Administration, Cutaneous↗
PubMed1996

Chicken anti-protein A prevents Staphylococcus aureus protein A from binding to human and rabbit IgG in immunoassays and eliminates most false positive results.

This report demonstrates that chicken anti-protein A can prevent both soluble and surface-bound Staphylococcal protein A from binding to either human or rabbit IgG. In an ELISA assay, chicken anti-protein A prevented > 98% of the soluble protein A from binding to the human IgG-Fc coat. In a blotting assay, chicken anti-protein A prevented the membrane-bound protein A from interacting with the human IgG probe. When intact S. aureus (Cowan I strain) was bound to the surface of a microassay plate, chicken anti-protein A blocked > 98% of the cell wall protein A and permitted the probing of the surface components with human IgG. In another immunoassay, rabbit anti-enterotoxin A IgG was used to measure enterotoxin A concentrations in S. aureus culture medium supernatants after soluble protein A was blocked by chicken anti-protein A. Thus, the binding of chicken anti-protein A to protein A almost completely eliminates false positive results and permits the measurement of specific antibodies or antigens in a variety immunoassays where protein A is present.

Animals↗
PubMed1996

Staphylococcus aureus nasal carriage in rheumatoid arthritis: antibody response to toxic shock syndrome toxin-1.

OBJECTIVE: To determine the prevalence of Staphylococcus aureus nasal carriage and to compare antibody responses to two superantigens, staphylococcal toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxin A (SEA), in rheumatoid arthritis patients and normal subjects. METHODS: 88 rheumatoid arthritis patients and 110 control subjects were cultured for nasal carriage of S aureus; 62 isolates were bacteriophage typed. Twenty five patients and 11 spouses were tested for antibodies to TSST-1, SEA, and sonicate extracts of Bacteroides fragilis and Escherichia coli; 19 patients were HLA-DR typed. RESULTS: 50% of patients and 33% of normal subjects were S aureus carriers. Bacteriophage typing of isolates suggested significant differences between strains isolated from the two groups. Patients showed higher IgG (P = 0.0025) and IgA (P = 0.0372) antibody levels to TSST-1 than normal spouses and these responses were not related to rheumatoid factor titres or HLA-DR type. CONCLUSION: When compared to normals, rheumatoid arthritis patients more often carry S aureus in their nasal vestibule, carry a distinct subpopulation of S aureus strains, and have higher average antibody levels to TSST-1.

Adult↗
PubMed1993

Antibodies bound to nitrocellulose in acidic buffers retain biological activity.

This report compares the binding of proteins to nitrocellulose membranes in acidic buffers (pH 2 and 3) with binding in neutral buffer (pH 7). Initially, similar amounts of antibodies and other proteins bound to the nitrocellulose membrane in both acidic and neutral buffers. However, the susceptibility of individual proteins to displacement (stripping) from the membrane by the milk blocking agent depended on the pH of the buffer used to bind the proteins to the membrane. Most proteins that bound to nitrocellulose in acidic buffers were relatively resistant to milk-stripping compared to proteins bound in pH 7 buffer. Acid-binding of proteins to nitrocellulose also decreased the amount of protein that was stripped from the nitrocellulose membrane when Tween 20 was included in the washing buffer. After correcting for the amount of antibody remaining on the membrane after the milk block, it was found that acid-bound antibodies were unchanged in biological activity when compared with the same antibodies bound at neutral pH. These results suggest that acid-binding of proteins could increase the sensitivity of nitrocellulose membrane assays that use milk and/or Tween 20.

Animals↗
PubMed1992

Characterization of immune complex components by dot blot analysis.

A method is described for the characterization of immune complex components by dot blot analysis. After isolation by chromatographic techniques and precipitation with polyethylene glycol, immune complexes were dissociated in 0.1 M phosphate (pH 2) and bound to a nitrocellulose membrane in a dot blot unit. Biotinylated probes were then used to identify the following immune complex components: specific antigens, biologically active antibodies, antibody isotypes, antibody subclasses, antibody idiotypes, and rheumatoid factors. This nonradioactive procedure takes less than 2 h to perform and has been used to analyze immune complexes isolated from sera (rabbit and human) and synovial fluid (human).

Acids↗
PubMed1992

Microanatomic clonality of gamma delta T cells in human leishmaniasis lesions.

T cells bearing gamma delta Ag receptors accumulate in the lesions of patients with localized American cutaneous leishmaniasis (LCL), and are thought to be involved in immunity to the parasite. To obtain clues as to the nature of the Ag recognized by these cells, we analyzed the diversity of the TCR delta-chain in LCL lesions. Using mAb against variable (V) encoded determinants with immunoperoxidase, both V delta 1 and V delta 2 subpopulations were identified in the dermal granulomas. However, within the epidermis of LCL lesions, the majority of the gamma delta T cells were V delta 1 positive. PCR analysis of lesion-derived DNA using oligonucleotide primers for V and junctional (J) gene segments revealed preferential usage of J delta 1 in lesions compared with the peripheral blood of these patients. Nucleotide sequence analysis of the V-J junction indicated limited diversity of gamma delta T cells within specific microanatomic regions. In addition, use of a single diversity (D) gene segment, D delta 3, in V delta 2 cells in lesions was observed, as opposed to multiple D delta gene segment usage in the blood of the same individuals. The distribution, gene segment usage and clonality of gamma delta T cells in lesions of leishmaniasis was remarkably similar to that observed in leprosy. Therefore, gamma delta T cells responding to infection may recognize a limited set of nominal Ag, perhaps common to distinct pathogens and/or those expressed by the host. Our findings are most consistent with a model in which specific gamma delta T cells are clonally selected by these Ag in lesions and undergo oligoclonal expansion within a microanatomic region.

Amino Acid Sequence↗
PubMed1991

Binding of antibodies and other proteins to nitrocellulose in acidic, basic, and chaotropic buffers.

This report compares the binding of proteins to nitrocellulose membranes in acidic buffers (pH 2 and 3) with binding in neutral buffer (pH 7), basic buffers (pH 12 and 13), 8 M urea (pH 2, 3, and 7), and 6 M guanidine hydrochloride (pH unadjusted). Initially, similar amounts of antibodies and other proteins bound to the nitrocellulose membrane in all of these buffers and solvents. However, the susceptibility of individual proteins to displacement (stripping) from the membrane by the milk blocking agent depended on both the pH and the type of buffer or solvent used to bind the proteins to the membrane. Most proteins that were bound to nitrocellulose in acidic buffers were relatively resistant to milk stripping compared to proteins bound in pH 7 buffer. After correction for the amount of antibody remaining on the membrane after the milk block, it was found that acid-bound antibodies were unchanged in biological activity when compared with the same antibodies bound at neutral pH. These results suggest that acid binding of proteins could increase the sensitivity of nitrocellulose membrane assays using a milk block.

Animals↗
PubMed1991

The role of infections in the rheumatic diseases: molecular mimicry between bacterial and human stress proteins?

Infections can cause or exacerbate the rheumatic diseases in several ways, including immune cross-reactivity between bacterial heat shock proteins and similar proteins in normal human tissues. This may lead to autoimmunity in rheumatoid arthritis and systemic lupus. In addition, increased activation of the gene regulating the synthesis of a heat shock protein has been found in scleroderma fibroblasts. As an infection-induced model for other rheumatic diseases, rheumatic fever (RF), with its well-established link to prior group A streptococcal infection, will be revisited. The lessons learned from RF and other rheumatic diseases directly linked to infection will be applied to ankylosing spondylitis, rheumatoid arthritis, Sjogren's syndrome and polymyositis, for which a mounting body of circumstantial evidence suggests a probable infectious cause. The interplay of genetic susceptibility and infection with particular organisms and the implications of this new information for present and future therapy of the rheumatic diseases will also be presented.

Antigens, Bacterial↗
PubMed1990

Characterization of immune complexes by isoelectric focusing in agarose gels.

A method is described for the characterization of immune complexes on thin-layer agarose isoelectric focusing (IEF) gels. This method involves dissociating immune complexes and then maintaining this dissociation during IEF in agarose gels containing 9 M urea. After IEF, the immune complex components can be quantitatively transferred to nitrocellulose in less than 15 min, and a variety of immunostaining procedures can be used to probe these blotted components. No loss of biological activity was detected in any of the blotted components.

Animals↗
PubMed1990

Synthesis of specific IgG idiotypes by rheumatoid synovium.

Synovial tissue samples from 6 patients with rheumatoid arthritis were cultured, and the IgG antibodies isolated from the synovial culture supernatants were used to immunize rabbits to make 6 antiidiotypic (anti-Id) antibody preparations. After extensive adsorption, the rabbit anti-Id were tested in a solid-phase enzyme-linked immunosorbent assay (ELISA). Each anti-Id reacted predominantly with the immunizing synovial IgG and showed almost no reactivity with either pooled normal human serum IgG or with IgG from 50 normal donors. When identical amounts of matched rheumatoid arthritis serum IgG and synovial culture supernatant IgG were probed simultaneously with the corresponding rabbit anti-Id in an ELISA, 3 of 6 pairs demonstrated an increased concentration of specific idiotypes in the synovial culture supernatant IgG. Furthermore, when these 6 matched samples were subsequently analyzed by isoelectric focusing, individual IgG antibodies in 5 of 6 synovial IgG samples revealed enhanced reactivity with the corresponding rabbit anti-Id preparations, when compared with matched serum IgG. This increased synovial concentration of specific idiotypes detected by both the ELISA and isoelectric focusing was compatible with enhanced synovial tissue synthesis of the antibodies involved. These specific Id/anti-Id reactivities were not blocked by excess normal human Fc, Fab, or F(ab')2 fragments, indicating a lack of association of the stimulating synovial antibodies with rheumatoid factors or antibodies against other IgG fragments (pepsin agglutinators).

Arthritis, Rheumatoid↗
PubMed1989

Rehydratable agarose gels: application to isoelectric focusing in 9 molar urea.

A method is described for the preparation of rehydratable agarose gels, with specific application to the direct incorporation of 9 M urea and carrier ampholytes into rehydratable agarose gels for use in isoelectric focusing. After drying the agarose gel containing an uncharged linear polyacrylamide, one gel volume of a 9 M urea-carrier ampholyte solution is absorbed directly into the gel in 60 min, eliminating equilibration or dialysis of the gel in larger volumes of the 9 M urea-carrier ampholyte solution. Proteins with a molecular mass of 970,000 Da can be separated by isoelectric focusing in these rehydratable gels. The focused proteins can then be quantitatively transferred to nitrocellulose in less than 10 min, and any immunostaining procedure can be used to probe the blotted proteins. These agarose gels are easy to make, they rehydrate rapidly and they can be used in applications other than isoelectric focusing.

Acrylic Resins↗
PubMed1989

Inhibition of the streptavidin-biotin interaction by milk.

Nonfat dried milk is routinely used as a blocking agent and diluent in immunoassays. However, the data presented in this paper demonstrate that milk contains an inhibitor of the biotin-streptavidin interaction. It is recommended that milk be dialyzed or used at lower concentrations when it is employed as a diluent of streptavidin.

Animals↗
PubMed1988

Site-specific immobilization of antibodies by their oligosaccharide moieties to new hydrazide derivatized solid supports.

This report describes a new method for immobilization of antibodies to solid supports. Antibodies are bound to the solid supports by covalent bonds between aldehydes generated on the carbohydrate side chains of the antibody and hydrazide groups on the solid support. The hydrazone bonds that are formed are stable at least from pH 2-10, permitting the acid elution of antigens from the affinity column. Over 25 mg of affinity-purified rabbit IgG binds per ml of solid support, with most of the bound antibodies retaining biological activity. Advantages of this new affinity support over existing technology are discussed along with procedures for the preparation and use of affinity columns containing monoclonal or polyclonal antibodies.

Animals↗
PubMed1987

Site-directed immobilization of glycoproteins on hydrazide-containing solid supports.

Methods are described for the preparation and use of solid supports containing hydrazide functions for the immobilization of glycoproteins specifically through the oligosaccharide moieties. The solid supports are prepared from commercial "active ester" agarose by reaction with hydrazine hydrate. Glycoproteins are oxidized with sodium periodate, resulting in the production of aldehydes on the oligosaccharide moieties. Oxidized glycoprotein is then reacted with the hydrazide-derivatized solid support to produce stable hydrazone linkages. Data are presented for the optimization of binding of oxidized glycoprotein to hydrazide-derivatized agarose. Agarose hydrazide/glycoprotein gels were shown to be stable from pH 3 to 10 and activity studies using immobilized avidin show that this method of immobilization results in an increased "specific activity" of bound protein when compared with standard methods of immobilization.

Chromatography, Affinity↗
PubMed1986

Tween 20 removes antibodies and other proteins from nitrocellulose.

It has generally been assumed that the binding of most proteins to nitrocellulose is stable in the non-ionic detergent Tween 20. However, the following paper demonstrates that in immunoassays where antibodies or other proteins are bound directly to the nitrocellulose, 0.05% Tween 20 may dissociate these proteins from the membrane. The degree of dissociation appears to be dependent on the individual protein studied. Some antibodies and other proteins bind tightly to nitrocellulose and dissociation of these proteins by Tween 20 is barely detectable. In contrast, other proteins are nearly completely stripped from the nitrocellulose by the same detergent. Therefore, unless it is known from control experiments what proteins will or will not be dissociated from nitrocellulose by Tween 20, the routine use of Tween 20 in the development of Western blots, native blots and dot-blots should be discontinued.

Animals↗