Transfer of paraphenylenediamine delayed-type hypersensitivity: a comparative investigation in the guinea pig, using arteriovenous cross-transfusion and parabiosis.

Arteriovenous cross-transfusion and parabiosis were used to study transfer of paraphenylenediamine (PPDA) hypersensitivity in guinea pigs. Nine out of 10 transfusion experiments were successful, resulting in definite positive test reactions in the recipient animals, and the remaining experiment was evaluated as possibly positive. Six out of 10 parabiosis experiments were successful, a further 2 were negative and the remaining 2 were evaluated as possibly positive. The mean test reactions in the recipients were stronger in the transfusion experiments than in the parabiosis experiments (0.001 less than P less than 0.01 for 0.5% PPDA). In control experiments, where the "donors" were nonsensitized guinea pigs negative test reactions were obtained. It was concluded that the transfusion technique was the most reliable of the 2 methods, when studying transfer of PPDA hypersensitivity.

Sterile cutaneous pustules: a manifestation of primary irritancy? Identification of contact pustulogens.

An animal model (the rabbit) was used to define which of 8 chemicals caused pustule formation on topical application. Large occlusive chambers (diameter 12 mm), petrolatum as the vehicle and wrapping contributed to efficient occlusion and pustulation. Sodium lauryl sulfate and mecuric chloride gave reproducible results and clear dose-responses indicating that this pustulation is an expression of primary irritancy. Ammonium fluoride pustulation was not reproducible; croton oil pustules were more difficult to evaluate due to simultaneous erythema and edema. Sodium arsentate, nickel sulfate and potassium iodide pustules developed at sites where the skin barriers had been damaged by a stab injury. Benzalkonium chloride caused yellow staining and edema but not pustules. Because of lack of epidemiologic data, we do not know how frequently similar findings occur in man.

Apparent absence of local response to bone screws in guinea pigs with contact sensitivity.

Guinea pigs sensitized to nickel, cobalt, or chromium were used to study if impaired fixation occurred as a result of allergy against metal implants in bone. Screws made from stainless-steel (ASTM F55, F138-139) or cobalt chromium (ASTM F75-76) were inserted in the right and left proximal tibiae, and the mechanical strength of the fixation to the bone was evaluated after 4 months. In addition, we studied the histology on decalcified sections of the implant bone interface from the distal femur where the same type of screws had been inserted. To see if changes in bone density occurred in the proximal tibia as a result of allergy, the amount of ash was determined. Although the animals maintained their contact sensitivity throughout the experimental period, there were no differences between allergic and control animals for any of the parameters studied. All screws were well fixed in the tibia at the end of the experiment, and histologically we did not find any significant differences between allergic and control animals by qualitative examination. The experiment supports our earlier results from a 6-week experiment and indicates that contact allergy may be unimportant for the fate of orthopedic implants.

Structure-activity relationship as a tool in contact allergy risk assessment.

About 3000 substances are known to cause contact allergy (type IV allergy). The possibility of predicting the sensitizing capacity of a substance by examining its chemical structure is discussed on the basis of the authors' own experience and of literature data. Since other factors also influence the allergenic activity of a compound, indications based on chemical considerations must be confirmed experimentally in animals because no in vitro methods yet exist.

Nickel chloride or nickel sulfate? Irritation from patch-test preparations as assessed by laser Doppler flowmetry.

To obtain an optimal test preparation for diagnosing nickel contact sensitivity, one can vary the nickel salt, vehicle and concentration, length of exposure, patches, and tape. Nickel chloride has been suggested as an alternative to nickel sulfate in the standard tray. However, a sensitive and noninvasive method of recording skin blood flow (laser Doppler flowmetry) showed in healthy subjects that the chloride was more irritating to the skin than the sulfate when petrolatum was used as vehicle. The naked eye could not discern this difference.

Is the skin affected by work at visual display terminals?

According to some reports, mainly from Norway and Sweden, visual display terminal work is suspected of causing skin rashes. In three different studies, we have tried to elucidate the question, and the results indicate that there might be a relation between VDT work and aggravation of some common skin diseases such as rosacea, seborrheic and atopic dermatitis, and acne. Whether this depends on physical, chemical, or psychological factors is still unknown.

Free radicals as potential mediators of metal-allergy: Ni2+- and Co2+-mediated free radical generation.

The generation of free radicals by Ni(2+) and Co(2+) was studied at physiological pH in H(2)O(2)-containing solutions in the absence and presence of various radical-mediating ligands and in human peripheral blood mononuclear cell (PBMC) cultures. With ESR spectroscopy, free radical species were identified and quantitated by spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Co(2+) generated hydroxyl radicals from H(2)O(2) in PBS solutions containing glutathione (GSH) or histidine (His). Omission of GSH or His from the reaction mixture significantly reduced the ESR-signal, indicating the importance of metal-chelation in free radical generation. Carnosine did not significantly enhance the reactivity of Co(2+) toward H(2)O(2), whereas cysteine (Cys) and N-acetylcysteine (NAC) suppressed free radical generation. Under identical reaction conditions, Ni(2+) was markedly less reactive toward H(2)O(2) in comparison with Co(2+). GSH, His, Cys and NAC did not enhance free radical generation of Ni(2+) from H(2)O(2). However, in the presence of carnosine weak but significantly enhanced ESR intensities were found. Incubation of PBMC cultures from healthy subjects with Co(2+) (10-50 microM) yielded the DMPO-.OH adduct, suggesting Co(2+)-mediated hydroxyl radical generation. In contrast, incubation of PBMC cultures with Ni(2+) (10-50 microM) did not produce a detectable ESR-signal. Ascorbic acid efficiently inhibited Co(2+)-mediated free radical generation in PBS solutions and PBMC cultures. The observed difference in free radical generating capacity between Ni(2+) and Co(2+) is of interest with respect to the absence of cross-reactivity between the two metal-ions in experimental allergic contact dermatitis.

Erythema-inducing effects of solvents following epicutaneous administration to man--studied by laser Doppler flowmetry.

Skin exposure to solvents can cause erythema, edema, scaling, and, eventually, irritant contact dermatitis. The irritant potential of chemicals is usually assessed by visual scoring, but in recent years a more objective measuring technique, laser Doppler flowmetry (LDF), has been introduced for the assessment of erythema. The method is noninvasive and allows continuous recording. In the present study 11 solvents were applied for 5 min or less to the volar forearms of a man and the kinetics of the response is shown. For seven solvents (dimethyl sulfoxide, trichloroethylene, n-hexane, carbon tetrachloride, toluene, 1,1,1-trichloroethane, 1,1,2-trichloroethane) an increase was found over the pretreatment values, whereas four solvents (methyl ethyl ketone, ethanol, propylene glycol, distilled water) did not influence blood flow. The findings are discussed in relation to the macroscopic picture (whitening and erythema) and in relation to previous studies of the edema-inducing effects of the same solvents on man and experimental animals. It is concluded that LDF is well worth trying in cases of marginal irritancy and for predictive testing, since it seems to be more sensitive and reliable than the naked eye.

Comparative percutaneous toxicity of ten industrial solvents in the guinea pig.

This report is part of a study on skin pathology, blood levels and percutaneous toxicity after the epicutaneous administration of solvents. The method used for the study of percutaneous toxicity differentiated between different types of solvents, and between different applied volumes of the same solvent. Five solvents caused some mortalities (in declining order: 2-chloroethanol, 1,1,2-trichloroethane, ethyleneglycolmonobutylether, carbontetrachloride, and dimethylformamide). Four solvents--benzene, toluene, 1,1,1-trichloroethane, and trichloroethylene--did not cause mortality, but a statisically significant effect on weight gain was observed. For n-hexane the weight gain did not differ (P greater than 0.2) from that of the control animals exposed to distilled water. For comparison, the same amounts of the solvents were injected intraperitoneally. There was a fairly good agreement between intraperitoneal and percutaneous toxicity, but slight deviations were observed for carbontetrachloride and dimethylformamide.

Work with video display terminals among office employees. V. Dermatologic factors.

According to some reports, mainly from Norway, work with a video display terminal (VDT) has been suspected to cause skin rashes. In conjunction with an epidemiologic study of some 550 office employees, 74 persons, who complained of skin symptoms, were examined by occupational dermatologists. The objective was to see whether the findings from earlier reports could be confirmed, whether any type of rash could be suspected to depend on VDT work, and whether positive findings might be explained by means of physical data. Many different diagnoses were made, but no case demonstrated the clinical picture described among VDT operators from Norway. Subjects with seborrheic dermatitis, acne, and rosacea were overrepresented in the exposed group. Whether this occurrence was due to physical factors, psychological factors, or pure chance is still unclear. This study and observations from our clinic imply that a relationship might exist between VDT work and aggravation of seborrheic dermatitis, acne, and rosacea and probably poikiloderma of Civatte.

The morphology of chromium allergic skin reactions at electron microscopic resolution: studies in man and guinea pig.

Previous studies on clinical patch test reactions have been expanded to short-term studies in humans hypersensitive to chromium. Preliminary results are discussed in relation to experiments in normal and sensitized guinea pigs.

Immunoglobulin E, atopy, and nickel allergy.

Statements in the literature as to whether a relation exists between atopy and nickel allergy are contradictory. I have attempted to make the diagnosis of the two states more stringent by using immunoglobulin E (IgE) determinations and serial dilution tests with nickel sulfate. The IgE determinations proved to be of less value in cases of pure eczema, and nonspecific (?) increases were sometimes observed. The incidence of family atopy was higher in other reports, but the clinical significance of this was unclear. Serial dilution tests gave important information, and a warning is issued against uncritical acceptance of a test reaction with 5.0% nickel sulfate in a patient with suspected atopy.

Skin pathology following epicutaneous exposure to seven organic solvents.

1,1,1,-Trichloroethane, benzene, trichloroethylene, tetrachloroethylene, dibromoethane, 1,2-dichloroethane, and 1,1,2,2-tetrachloroethane were applied to the skin of guinea-pigs for histopathological studies. Biopsies taken at different times of exposure showed the presence of karyopyknosis for all solvents tested; 1,1,1-trichloroethane, benzene, trichloroethylene, and tetrachloroethylene showed karyolysis; 1,1,1-trichloroethane, benzene, trichloroethylene, tetrachloroethylene, and dichloroethane induced spongiosis. All solvents, except 1,1,2,2-tetrachloroethane, produced junctional separation. Pseudoeosinophilic infiltration occurred for all solvents, except for 1,2-dichloroethane. The results are discussed in terms of occupational hazards and in relation to parallel studies on blood uptake and systemic toxicity at epicutaneous administration.

The value and limitations of protective gloves in medical health service: part II.

The value of protective gloves in the health care environment is well known. However, these gloves are not perfect. Some are permeable to microorganisms and various chemicals, and/or result in side effects for health care professionals. Gloves that offer the greatest protection and least side effects are highly desirable. Protection against microorganisms and protection against chemicals used in health care are described in Part II of this three-part series.

The value and limitations of protective gloves in medical health service: Part I.

The value of protective gloves in the health care environment is well known. However, these gloves are not perfect. Some are permeable to microorganisms and various chemicals, and/or result in side effects for health care professionals. Gloves that offer the greatest protection and least side effects are highly desirable. Field of application rules and regulations, materials and manufacturing, and test methods of protective gloves are described in Part I of this three part series.

The value and limitations of protective gloves in medical health service: Part III.

The value of protective gloves in the health care environment is well known. However, these gloves are not perfect. Some are permeable to microorganisms and various chemicals, and/or result in side effects for health care professionals. Gloves that offer the greatest protection and least side effects are highly desirable. Limitations of glove use due to side effects, and glove selection and therapeutic alternatives are described in Part III of this three-part series.