Experimental photoallergic contact dermatitis: a mouse model.

We have induced photoallergic contact dermatitis in mice to 3,3',4',5 tetrachlorosalicylanilide (TCSA), chlorpromazine and 6-methylcoumarin. These compounds are known to produce photoallergic contact dermatitis in humans. The photoallergic contact dermatitis reaction in the mouse is immunologically specific viz.

Usefulness and limitations of various guinea-pig test methods in detecting human skin sensitizers-validation of guinea-pig tests for skin hypersensitivity.

Several guinea-pig predictive test methods were evaluated by comparison of results with those obtained with human predictive tests, using ten compounds that have been used in cosmetics. The method involves the statistical analysis of the frequency with which guinea-pig tests agree with the findings of tests in humans. In addition, the frequencies of false positive and false negative predictive findings are considered and statistically analysed.

The spontaneous loss of contact sensitivity in the mouse does not require B cells.

In the mouse, allergic contact dermatitis to the strong contact allergen dinitrofluorobenzene is maximal 5 to 6 days after sensitization and rapidly fades in the succeeding days. It has been proposed that this loss of T-cell reactivity depends on feedback inhibition by anti-idiotypic antibody of the expression of allergic contact dermatitis. We have examined this question by studying the course of allergic contact dermatitis in mice made B-cell deficient by the chronic administration from birth of a heterologous antibody with specificity for mouse IgM.

Regional lymph node x-radiation suppresses allograft rejection.

We studied the effect of a single dose of x-radiation given to the regional lymph nodes on allograft rejection. Our model was an A-strain tumor, transplanted to C57B1/6, DBA/2, and C57B1/6 x CBA hosts. Irradiation (1,000 rad) of the regional lymph nodes inhibited graft rejection, as judged by increased tumor growth, slower rejection, and, in the case of DBA/2 mice, by fewer regressions; irradiation of the contralateral lymph nodes did not have this effect.

Regulation of contact allergy in the B cell--deficient mouse.

We have examined the obligate role of B cells in the regulation of allergic contact dermatitis. Our model is ACD in mice made B cell deficient by the chronic administration from birth of a goat antisera to mouse IgM. The following ACD phenomena are well demonstrated in these mice: (1) acquisition and expression of ACD, (2) spontaneous waning of ACD soon after sensitization, (3) immunological tolerance induced by pretreatment with either parenteral hapten or haptenated spleen cells, (4) immunopotentiation by means of either cyclophosphamide or the local administration of a suspension of killed C.

Allergic contact dermatitis in the hamster.

Allergic contact dermatitis to strong, low molecular weight contact allergens can regularly be induced in the hamster. By its clinical course, histopathology and susceptibility to intensification with complete Freund's adjuvant, this hypersensitivity appears congruent with the allergic contact dermatitis observed in other experimental animals and the allergic contact dermatitis seen in humans. Further, in the hamster, we find that pretreatment with cyclophosphamide intensifies the acquisition of allergic contact dermatitis to dinitrochlorobenzene and to oxazolone; the target of cyclophosphamide immunopotentiation has been shown in the mouse and guinea pig to be a regulator suppressor cell.

Cyclophosphamide intensifies the acquisition of allergic contact dermatitis in mice rendered B-cell deficient by heterologous anti-IgM antisera.

Treatment with cyclophosphamide (Cy) before contact sensitization regularly intensifies the induced sensitivity. The immunopotentiation is specific and appears due to toxicity for suppressor cells. It has been proposed that the target of Cy immunopotentiation is a suppressor B cell.

Halothane solubility in blood during cardiopulmonary bypass: the effect of haemodilution and hypothermia.

The influence of haemodilution and cooling on the solubility of halothane in blood during cardiopulmonary bypass was studied in six normothermic and six hypothermic patients undergoing open-heart operations. The solubility of halothane in blood was 2.17 at 30 degrees C and 1.

Noninvasive evaluation of cardiovascular effects of preoperative sedation in children.

The cardiovascular effects of two premedication regimes used in paediatric anaesthesia were studied. Eleven patients received rectal methohexitone (22 mg - kg) and 11 patients received intramuscular Innovar (0.03 ml - kg).

Half-body x-ray suppresses the acquisition of delayed-type hypersensitivity in the mouse.

800 R half-body x-ray suppressed the acquisition of allergic contact dermatitis in mice (1) if the x-ray field included the lymph nodes regional to the sensitization site, and (2) when x-ray was given during, but not immediately before, induction of the sensitivity.

Establishment and characterization of human neuroblastoma cell lines.

Three new tissue culture cell lines, CHP-100, CHP-126, and CHP-134, have been established from explant cultures of human neuroblastoma. The cell lines have been characterized with respect to morphology, chromosomes constitution, growth, neural enzyme content, and their ability to grow in nude mice. The cells grow as dense masses comprised of fibroblast-or neuroblast-like cells with small processes.

Invasion and metastasis of a xenogeneic tumor in nude mice.

When aliquots of a malignant hamster tumor were transplanted to nude mice and to hamsters, the tumor showed 1) more rapid growth in the hamster, 2) local invasion and metastasis in both species, and 3) occasional spontaneous regression in the nude mouse.

Allergic contact dermatitis to low molecular weight allergens in the chicken.

We have produced allergic contact dermatitis (ACD) to low molecular weight allergens in the chicken. Sensitization was induced by the application of a high concentration of allergen to a site on the comb previously treated with dimethyl sulfoxide. Challenge, which was made on the wattle with a nonirritating concentration of allergen, resulted in a dermatitis that was grossly and histologically similar to ACD in mammals.

Allergic contact dermatitis in the B-cell deficient chicken.

Allergic contact dermatitis to oxazolone was induced in three chickens rendered B-cell deficient by combined chemical bursectomy with testosterone and cyclophosphamide.

Mycobacterial RNA. A comparison with intact mycobacteria for suppression of murine tumor growth.

Our experimental data imply the following: (1) An RNA-rich fraction isolated from H37Ra, and intact H37Ra, are effective agents for suppression of tumor growth. (2) For suppression of two chemically-induced tumors with both RNA and H37Ra, direct contact with tumor is necessary. This may not be the case with other tumors in different strains of syngeneic mice.

Specific acquired immune unresponsiveness to contact allergens with cyclophosphamide in the mouse.

Treatment with cyclophosphamide (Cy) can modulate the acquisition of allergic contact dermatitis in the mouse. We compared the effect of a single dose of Cy given at different times before or after allergen. Cy one or more days prior to allergen intensified, and Cy several days after allergen inhibited the acquisition of sensitivity.