Steel Cage Research Articles

OLFACTORY DISCRIMINATION LEARNING IN THE VIRGINIA OPOSSUM

As in other marsupials, the brain of the Virginia opossum (Didelphis virginiana) has no corpus callosum connecting the cerebral hemispheres, making it suitable for splitbrain experiments of interhemispheric communication (Herring, Mason, Doolittle, & Scarrett, 1966). In previous split-brain experiments done on rats, cats, and monkeys, the sensory modalities of touch and vision were studied. In the opossum, however, neither of these modalities was suitable due to the bilateral cortical representarion of touch stimuli and the inaccessibility of the optic chiasm which must be sectioned in vision srudies (Lende, 1963). T he sensory modality of olfaction was chosen for study because of the accessibility of the olfactory bulbs and the availability of data on techniques of electrophysiological recording from the olfactory bulbs of opossums (Phillips, 1962). To test the practicality of using olfaction to study interhemispheric communication, in the present study we attempted to teach opossums an olfactory discrimination. Method.-Four adult Virginia opossums, one male and three females, were Ss. They were housed individually in 24-in. x 24-in. X 36-in. stainless steel cages with water continuously available. Ss were given pelleted dog food for 1 hr. each day for 3 days prior to the beginning of maze trials. The apparatus was a cross-maze used as a T-maze in this experiment. The start box and goal boxes were 12 in. X 12 in. x 30 in. (inside dimensions) and the choice point connecting these was 12 in. X 12 in. X 12 in. The maze had black plastic walls, a clear plastic top, and a grid floor. The guillotine doors of the maze were electronically controlled from a monitor in a room adjacent to the maze room. The maze room was 8 ft. x 10 fc. x 8 ft. and was dark during the running of Ss, with the exception of light from photocells located 6 in. from the end of each arm of the maze. A 5-in. X 4-in. X 3-in. glass dish was placed in each goal box near the choice point and a 5-in. X 4-in. glass plate was placed at the end of each goal box away from the choice point. The olfactory stimulus was two drops of oil of wintergreen in one of the dishes and one drop in the corresponding plate. The glassware was washed out and a fresh stimulus applied at the beginning of each day's trials. A trial required placing the glassware with the olfactory stimulus randomly in one or the other goal box and allowing S to run from the start box into one of the goal boxes where a photocell switch was activated closing the guillotine doors. On the glass plate in the goal box containing the olfactory stimulus was the reinforcement, an M&M candy which is palatable and easy to use.

Cancer treatment: immunologic and chemotherapeutic interrelationships.

OUR EARLIER WORK documented that surgical reduction of large and well-established transplantable tumors permits noncurative courses of appropriate anticancer agents to completely eradicate the residual remnants of established tumor tissue. 1,2 The probability that these findings were generally applicable was suggested by the variety of agents (6-mercaptopurine, thio-tepa, cyclophosphamide [Cytoxan], 6-aminonicotinamide and puromycin) demonstrated to produce these results, and the multiple types of tumor (RC, Sarcoma 180, Walker 256) employed in 3 strains of mice and in 1 rat tumor. The present communication reports data demonstrating immune mechanisms as responsible for the observed inverse relationship between chemotherapeutic cure and tumor size (that is, the smaller the tumor, the greater the chemotherapeutic cure rate). In addition, chemotherapeutic cure of spontaneous tumors by means of the above experimental design is also reported. Materials and Methods The animals, housed in stainless steel and plastic cages, with ad libitum access to food (standard laboratory

Influence of cage type and dietary zinc oxide upon molybdenum toxicity.

Molybdenum-fed rats housed in galvanized cages gained less weight and had lower hemoglobin levels than similarly fed rats housed in stainless steel cages. Since similar effects were produced in rats housed in stainless steel cages by increasing the zinc in their diets, it was concluded that zinc consumed by chewing on zinc-coated cages was responsible for the abnormalities noted.

Influence of Cage Type and Dietary Zinc Oxide upon Molybdenum Toxicity

Molybdenum-fed rats housed in galvanized cages gained less weight and had lower hemoglobin levels than similarly fed rats housed in stainless steel cages. Since similar effects were produced in rats housed in stainless steel cages by increasing the zinc in their diets, it was concluded that zinc consumed by chewing on zinc-coated cages was responsible for the abnormalities noted.

The Impact of Technology

Technology is only a crutch for meaningful composition today. ULRICH FRANZEN The central problem which faces us is that we now design buildings in a cultural situation literally without precedent in human history. The architect is confronted with a totally new order of problems. He might draw a little consolation from this fact. It often seems to him that life is difficult; I think it is difficult, more difficult than it ever was before for architects. The impact of modern industrial technology upon contemporary architecture can be easily traced at every level theory, practice, finished product. The effect is most clear and most poignant at the theoretical level. Nineteenth-century technology set in motion among architects a whole train of speculation as to its significance, its probable course of development and the possible responses of architecture to it. This speculation spread in steadily widening circles, involving all the theoreticians of the past century and a half. Greenough, Pugin, Ruskin, Viollet-le-Duc; Sullivan, Wright and Geoffrey Scott; Le-Corbusier, Gropius and Mumford: all these men were activated by the shock waves of the impact of technology. Nor have these speculations ceased. On the contrary, the implications of technology for architecture are, in many ways, more ominous and obscure today than they were a hundred years ago. These successive waves of speculation are also revealed with great clarity in the architecture of the period. Each has left its deposit and these the historians can trace as easily as the geologist reads his core or the archaeologist his trench. It is a stratigraphy of unparalleled confusion. For though technology, by its sheer mastery of external nature, has made possible unprecedented advances in architecture it has, by the same ironic token, made possible more bad architecture than the world has ever seen before. And this, I think, is our central problem; that for every great building technology has given us, it has given us five million so much worse than was ever possible before that it is not even funny. Architecture unlike the fine arts is at once the prince and the prisoner of the kingdom of necessity. It can never escape the iron laws of physics: indeed its greatest examples are precisely those in which these laws have been most scrupulously observed. The majesty of such constructions as Hadrian's Villa or Chartres Cathedral springs from the most exact and elegant knowledge of the limits and potentials of masonry vaulting. Acceptance, not defiance, of the laws of statics was the basis of all pre-industrial architecture. Because modern technology has so extended man's power over external nature, modern architects have often acted as though these iron laws had been repealed. The result, for perhaps the first time in all history, was bad architecture ugly to look at, unsatisfactory in use. One of today's basic assumptions is that architecture, thanks to moder technology, has made great advances in the past century. In many respects, of course, this is true. But the implication is that these advances have been steady and continuous and that we stand now at some pinnacle of accomplishment. Unfortunately for our complacency, this is not the case. The great germinal structures of the past hundred years are not evenly distributed throughout its span; on the contrary, they fall in clusters, and rather closer to the beginning of the period than to its end. If, for the sake of brevity, we simplify the historical record, then we may take Joseph Paxton's Crystal Palace (1851) as marking the opening of an era. Here was the first western structure which clearly demonstrated the arrival of a new period. It not only used the materials of the new technology iron and glass but it used them in an explicitly novel way, purged of all reliance on historically determined form. It is a moot question whether we have advanced a jot or a tittle past Joseph Paxton's accomplishment of 110 years ago. We do not find this new architectural idiom immediately adopted by the West. On the contrary, four or five decades elapse before we find a statement of equal clarity and vigor in Sullivan's use of steel and glass in the multi-story Schlesinger Building of 1899; here was a perfect understanding not only of steel cage construction but, even more important, of the esthetic expression of its essen8

Studies of time-dose relationships: the effect of fractionation.

A recent review of the literature on time-dose relationships (1) suggested the possibility of improving the results of radiation therapy in certain circumstances by optimum timing of the individual treatments in a series. This particular aspect of the time factor is based on the theory that there are radiosensitive and radioresistant periods during the overall time of treatment, occurring as a result of temporary arrest of mitosis by irradiation. Since cells are most sensitive during mitosis, this period of arrest is a radioresistant period and radiation given during this time would be relatively ineffective; if irradiation were delayed until resumption of mitosis, it would fall into a radiosensitive period and produce a correspondingly greater effect. This theory was explored by Koller and Smithers (3) in a clinical experiment in which they took serial biopsies of six skin carcinomas during the treatment course and adjusted their treatment accordingly; that is, if they found no or few cells in mitosis they delayed treatment, but if they found many cells in mitosis they gave a treatment. In this way they were able to obtain good results with lower doses than they had used with daily treatment. Since this procedure is not practical in routine radiotherapy, it was decided to test the possibility of finding a predetermined fractionation plan which would fit a sufficient number of tumor-bearing individuals so that a better response for the group as a whole would be obtained. This had been tried for three types of tumors by Sambrook and co-workers (9) and it was their impression that responses differed, but with only 9 patients definite conclusions were difficult. The tumor chosen for this study is the spontaneous mammary adenocarcinoma of C3H mice. The mice were obtained from the Roscoe B. Jackson Memorial Laboratory, Bar Harbor, Maine, and later, when it was unable to supply sufficient numbers, from the Cumberland View Farms in Tennessee. No differences were observed between the two groups. The mice were kept in stainless steel cages containing cedar shavings. They were fed Purina Laboratory Chow and had free access to water at all times. They were usually kept about ten days after arrival to become accustomed to their new enviromnent before treatment was begun, but in a few instances mice with larger tumors were treated four days after arrival. In order to minimize “cage effects” (8), equal numbers of mice from groups being compared were kept in the same cage. An attempt was made to have the tumors of as nearly the same size as possible. The mice were identified by cage number, location of tumor, and sometimes by clipping the hair from one leg. Treatment plans were assigned by selecting a mouse, shuffling the record cards, and choosing a card at random. Several means of immobilizing the mice for treatment were tried and a method was devised which proved practical.