Cutaneous receptive field enlargement following skin-grafting in the frog, D. pictus

Misdirected wiping responses occur in Discoglossus pictus frogs when skin-grafted early in larval life. Cutaneous receptive fields (CRF) for various peripheral nerve branches were mapped electrophysiologically in control and skin-grafted frogs. The ventrolateral nerve branch (VL) frequently provided innervation for significant areas of dorsal skin in both control and skin-grafted animals. Although the VL crossed over onto dorsal skin areas in some skin-grafted frogs giving rise to misdirected reflexes, these dorsal extensions frequently failed to include all skin areas from which the maladaptive reflexes could be elicited. It was concluded that misdirected reflexes are mediated via dorsal nerve branches occupying normal mid-dorsal areas of the back.

Receptive fields of cutaneous mechanoceptive neurons in the frog, Discoglossus pictus, following skin transplantation at larval stages

The receptive fields of individual spinal ganglion cells were mapped in frogs in which a large patch of belly skin had been transplanted to the back prior to metamorphosis. Wiping reflexes aimed at the belly could be elicited both from regenerated normal and transplanted belly skin. We concluded that the sensory neurons mediating misdirected responses could not be the same ones as those mediating normal wipes, since unit receptive fields were either on normal or on grafted belly skin, but never both. A proposed mechanism for explaining the origin of cutaneous reflex connections on the basis of selective innervation of peripheral tissues could hereby be discarded.

Effect of cutaneous stimulation on the development of misdirected wiping reflexes in skin-grafted Discoglossus pictus

The frog, Discoglossus pictus, has been studied with respect to wiping reflex behavior developing after skin rotations performed at larval stages. Misdirected wiping reflexes were obtained only from belly skin-grafts placed on the animals' back; back skin-grafts on the belly failed to elicit any misdirected limb movements in this species. We found that misdirected reflexes occurred more readily in 3-week and older animals if not subjected to any previous test experience, than in younger naive frogs. Frogs that had been exposed to daily cutaneous stimulation between 2 to 4 weeks after metamorphosis showed a delayed development of misdirected responses.

Gonococcal ribosomes as skin test antigens. I. Preliminary tests of sensitivity and specificity

Ribosomes isolated from N. gonorrhoeae and N. meningitidis were used as skin test antigens in guinea-pigs which had been previously sensitized with killed Neisseria cells in incomplete Freund adjuvant. Intradermal injection of ribosomes from skin test dose N. gonorrhoeae into the skin of animals sensitized to the homologous organism was characterized by a specificity based upon ribosomal skin test dose 50's (STD50) sensitivity which was at least five-fold greater than that of the animals sensitized to the heterologous organism. The sensitized guinea-pigs had lost their skin-test reactivity within 3 months of the cessation of immunization but regained it immediately on reimmunization. The results of this model system indicate that gonococcal ribosomes may be used as antigens in skin testing or other testing modes in gonorrhoea.

Delayed hypersensitivity reactions provoked by ribosomes from acid-fast bacilli: physical characteristics and immunological aspects of core ribosomal proteins from Mycobacterium smegmatis

Ribosomal subunits from Mycobacterium smegmatis were analyzed by using sedimentation velocity, sedimentation equilibrium, and acrylamide gel electrophoresis experiments. These s(20.w) values for the subunits are 48.7S and 28.1S. The molecular weight of the 49S subunit is about 1.65 x 10(6), and that of the 28S subunit is 7.8 x 10(5). Both subunits contain about 37% protein and 63% ribonucleic acid. A protein-deficient particle having an s(20.w) value of 15.7S contains about 11% protein and 89% ribonucleic acid. Skin tests showed all subunits and proteins to be active as agents in provoking delayed hypersensitivity, but the 16S protein-deficient particle, as well as the proteins derived from it, was more specific than the subunits themselves.

Resistance of mice to infection with Friend disease virus after subcutaneous injection of Friend virus and Friend spleen cells

Swiss mice injected subcutaneously with suspensions of spleen cells or an extract of spleens from mice infected with Friend virus develop resistance to subsequent intravenous inoculation of Friend virus. A single injection of either Friend virus or Friend cells induces resistance. Immunized mice display resistance when challenged 6 months after immunization and survive for at least 20 weeks after infection. Neutralization tests indicate that serum, but not lymphoid cells of resistant animals, can neutralize Friend virus. In vitro neutralization tests indicate that residence of virus within the peritoneal cavity of immune mice for 1 h sharply reduces the infective titer of the virus.

Ribosomes of acid-fast bacilli: immunogenicity, serology, and in vitro correlates of delayed hypersensitivity

Ribosomal fractions obtained from Mycobacterium bovis (BCG) and M. smegmatis (strain butyricum) were studied to determine their antigenicity, their ability to stimulate the production of soluble mediators of delayed hypersensitivity (in vitro correlates) by sensitized peritoneal exudate cells, and the antigenic relations of ribosomal antigens of BCG to BCG protoplasm and H37Rv culture filtrates. The crude ribosomes and the 50-30S ribosomal subunit pool obtained from each of the organisms induced both delayed and immediate hypersensitivity when injected in incomplete Freund adjuvant into rabbits, and skin reactions could be elicited in sensitized rabbits with those antigens. The crude ribosomes and 50-30S ribosomal subunit pool of M. smegmatis stimulated lymphocytes of guinea pigs sensitized with viable organisms to produce macrophage migration inhibition factor. Comparable ribosomal fractions from BCG bacilli caused lymphocytes of guinea pigs sensitized with viable M. bovis (BCG) to produce skin reactive factor. Immunoelectrophoretic studies showed that H37Rv culture filtrate, protoplasm, crude ribosomes, and 50-30S ribosomal subunits of BCG contain multiple precipitinogens and that many of these were shared between the different antigen systems. Comparative electrophoresis revealed that BCG protoplasm and H37Rv culture filtrate shared a major portion of their components with each other and relatively few with ribosomal systems. The ribosomal systems shared the major portion of their components with each other and relatively few with the other antigen systems.

Herpesvirus hominis type 2 infections in rabbits: effect of prior immunization with attenuated Mycobacterium bovis (BCG) cells

Angora, New Zealand, and Dutch-belted rabbits were tested for their susceptibility to graded doses of Herpesvirus hominis type 2 administered by vaginal instillation, intracorneal injection, and scarification of the cornea. Central nervous system involvement and death occurred after infection by the various routes employed. Prior immunization of Dutch-belted and New Zealand rabbits with viable Mycobacterium bovis (BCG) cells injected intravenously provided protection against subsequent infections with type 2 virus.

Delayed hypersensitivity reactions provoked by ribosomes from acid-fast bacilli. I. Ribosomal isolation, characterization, delayed hypersensitivity, and specificity

Ribosomes and ribosomal subunits of Mycobacterium bovis (strain BCG) and M. smegmatis have been isolated and employed as skin test antigens in guinea pigs sensitized with homologous or heterologous organisms. Ribosomes and ribosomal subunits were found to be potent antigens for skin test purposes, and the 30S subunits were found to be more specific and active than the 50S subunits.

Neuronal specification of cutaneous nerves through connections with skin grafts in the frog

Skin grafts were rotated 180 degrees in frog tadpoles. After metamorphosis, cutaneous reflexes were tested, and the receptive fields of cutaneous nerves were mapped electrophysiologically. Accurately localized limb movements were elicited by mechanical stimulation of normal skin, or of dorsal skin reimplanted on the back after 180-degree rotation. Reflexes misdirected to the original site of the stimulated skin were elicited from dorsoventrally inverted grafts, but not from anteroposteriorly inverted grafts. In most cases, the local nerves supplied the grafts, and each nerve entered the skin within its own receptive field. This observation eliminated the possibility that misdirected reflexes were due to selective regrowth of cutaneous nerves. We concluded that cutaneous nerves formed central synaptic associations which were specified by their new terminal connections with grafted skin.