James M. Bowen

Pre- and postreinforcement delay with a small number of acquisition trials

Three groups of rats were given 5 acquisition and 13 extinction trials in a straight alley. Group treatments were: (1) immediate reward (R), (2) 20 sec. delay in goal box followed by reward (D-R), (3) immediate reward followed by 20 sec. nonreinforcement confinement in the goal box (R-D). Groups D-R and R-D were not reliably different but both were more resistant to extinction that Group R. There were no significant differences in acquisition. The data may be explained by a sequential analysis.

A quantitative immunobinding radioimmunoassay for antigens attached to nitrocellulose paper

An immunobinding assay is described that tests antigens attached to nitrocellulose paper against antisera contained in microtiter plates. In comparison to a conventional microtiter plate radioimmunoassay, the nitrocellulose paper radioimmunoassay is clearly superior in both antigen attachment and antibody binding. Studies using bovine serum albumin and human IgG demonstrated superior antigen attachment extending from 5-fold in a physiological solution, to 50-fold in 50% fetal calf serum, to over 1000-fold in detergent solutions. With titrations using a rabbit anti-human IgG serum, the antibody binding in the nitrocellulose paper radioimmunoassay averaged over 5 times the binding in the microtiter plate radioimmunoassay. The nitrocellulose paper radioimmunoassay was also modified to quantitate human IgG. With this assay, 15 pg of human IgG inhibited the antibody binding by 50%. The nitrocellulose paper radioimmunoassay is easy to perform, and, since it combines the antigen-binding properties of the nitrocellulose paper with the convenience of assaying samples microtiter plates, this assay should prove useful for investigating the many antigens that attach to nitrocellulose paper.

Virus-Like Particles in a Case of Human Prostate Carcinoma

Two morphologically different types of intracisternal virus-like particles were observed electron microscopically in a biopsy specimen of human prostate cancer. Particles of one type were 150-200 nm in diameter and contained either an electron-dense core or two concentric inner layers. Particles of the other type were smaller, 80-100 nm in diameter, and appeared mostly in filamentous or chainlike formation. Both types of particles and budding were observed in endoplasmic cavities of epithelial tumor cells. The particles had ultrastructural characteristics that suggested a viral nature but were different from the known type B, type C, or type H (hamster type R) virus particles. This was the first election microscopic observation in prostate cancer of virus-like particles similar to those previously reported in a case of human breast carcinoma.

Virus-augmented delayed hypersensitivity skin tests in gynecological malignancies

SummaryCultured human tumor cells of various histologic origins were infected with PR8/A/34 influenza virus. Nonviable crude membrane extracts were derived from the infected and uninfected cells. The extracts were coded and tested for their ability to produce delayed hypersensitivity skin reactions (DHSR) in allogeneic patients with squamous uterine cervical carcinoma, epithelial ovarian carcinoma, and malignant melanoma. Augmented antigen sensitivity to the virus-modified extracts compared with virus alone or to the unmodified extracts was observed in all patient groups. There was insufficient specificity to delineate a response by individual tumor type and related tumor extract, but some of the observed responses suggested tumor or organ site associations. Cervical carcinoma patients reacted more frequently to the virus-modified cervix extract, which also produced a high frequency of response in patients with ovarian carcinoma and melanoma. Ovarian carcinoma patients demonstrated increased sensitivity to both virus-modified ovarian carcinoma extracts, although 14 of 21 patients also showed responsiveness to one of the unmodified ovarian extracts. Malignant melanoma patients showed increased sensitivity to all virus-modified extracts except one of two derived from the ovarian carcinoma, and demonstrated a significantly augmented response to the virus-modified melanoma extract when the response to this extract was compared with that in ovarian carcinoma patients.The augmented reactions appear to be due to an association of the PR8 virus and as yet undetermined cellular components rather than to the virus alone. The possible involvement of tumor-associated determinants and the clinical significance of this phenomenon require further investigation.

Synthesis of Specific Transformation-Associated Proteins (TAPs) in Two Rat Cell Lines is Closely Related to the Expression of the v-mos Gene Product of Moloney Murine Sarcoma Virus (Mo-MSV)

The 6M2 cell line was established by transformation of normal rat kidney cells with the ts110 mutant of Moloney murine sarcoma virus (Mo-MSV). P85gag-mos was found to be the only known viral-transforming protein in this cell system. Previously, we described the detection in 6M2 cells of rat-specific transformation-associated proteins (TAPs) using a monoclonal antibody (MC). In this study, we used MC to investigate further the expression of TAPs at different temperatures and the time course of turn-on and shut-off of TAPs upon temperature shifting. It was found that TAPs were expressed at 24, 28 and 33 degrees C, but not at 37 and 39 degrees C. In experiments of temperature shifting, TAPs reappeared in about 6 h in 6M2 cells after the temperature was shifted from 39 to 33 degrees C, following closely the reappearance of P85gag-mos. The data in this communication support the notion that TAPs might be activated by the v-mos gene product during the process of transformation.

Occurrence of the partial reinforcement extinction effect after only one NRNR sequence of trials

Evidence is presented which demonstrates that the partial reinforcement extinction effect occurs reliably after only one NRNR sequence of trials which is preceded by a series of continuously rewarded trials.

Discrimination learning as a function of internal stimuli

Twenty-four rats received irregular 50% partial reinforcement. Half the intertrial intervals were 15 sec. and half were 5 min. For 12 Ss, consideration of both the goal event of the previous trial and length of the intertrial interval allowed reliable prediction of the goal event on the ensuing trial. The remaining 12 Ss constituted a control group. The experimental Ss ran significantly faster on reinforced than nonreinforced trials at both short and long intertrial intervals, though discrimination was poor at the longer interval.

Effect of post-reward confinement on choice behavior

Twenty rats learned a position preference in a Tmaze. The Ss were then matched and divided into two groups. Group C received two free and two forced choices daily so that each S entered both sides equally often and received 10 sec. reward regardless of the side entered. Group PRS received the same treatment except that if a S chose the side opposite to which it had been trained, it received a 30 sec. goal box confinement following the reward. On free choice trials, Group C chose the side opposite to which it had been trained significantly more times than Group PRC.

Rat transformation-associated proteins (TAP) induced by Moloney murine sarcoma virus interact with specific receptors on normal rat kidney cells

In this report, data are presented to show that transformation-associated proteins (TAP) secreted from the transformed 6M2 cells have mitogenic activities in the stimulation of DNA synthesis and proliferation of normal rat kidney (NRK-2) cells and of nonpermissively grown 6M2 cells. TAP also bound specifically to NRK-2 cells with a binding dissociation constant (Kd) of 1.4 pM. Approximately 2 X 10(5) binding sites per cell were found. Therefore, TAP may represent a set of virally-induced growth stimulatory factors.

Immune chromatography: a quantitative radioimmunological assay

Immune chromatography, a radioimmunological binding assay, employs paper chromatography to separate immune complexes from free antigen and antibodies. During chromatography free antigen and antibodies become distributed throughout the paper, while immune complexes remain near the bottoms of the strips. The chromatographic differences can be made quantitative by using either iodinated antigens or antibodies. Under these conditions nanogram quantities of antigen can be detected or antibodies in sera diluted several 1000-fold. The immune chromatography assay can also be performed as an indirect assay, since the paper strips are cut from nitrocellulose paper. In this case the immune components are absorbed by the paper during chromatography. Antigen is then detected with an iodinated second antibody. The indirect immune chromatography assay is particularly useful for identifying different sera that react with the same antigen. Reaction with the first serum before chromatography reduces the amount of antigen available to the second serum following chromatography. In addition to characterizing the immune chromatography procedure, we discuss the possible applications of chromatography assays for the quantitation of other types of molecular binding interactions.