Kettering University

About: Kettering University is a education organization based out in Flint, Michigan, United States. It is known for research contribution in the topics: Cancer & RNA. The organization has 6842 authors who have published 7689 publications receiving 337503 citations. The organization is also known as: GMI Engineering & Management Institute & General Motors Institute.

The nude mouse in cancer research

Abstract: Publisher Summary The nude mouse is considered a marvel as a laboratory animal and in many respects is uniquely qualified for in vivo model studies of human cancer. Most human tumors have been transplanted to nude mice and tumor lines are established with varying degrees of ease. It is noted that the additional immunosuppression of the mice or the use of very young animals can increase tumor growth and malignant expression. Other variables that affect tumor transplantation include the health of the mice, site of injection of the transplant, and specific properties or requirements of the human tumor cells. Hormone-dependent human tumors are grown in nude mice, either in special sites or after hormonal supplement. It is observed that the tumor growth rates differ in nude mice and in cancer patient and this tumor heterogeneity occasionally result in the growth of selected tumor components. These differences do not necessarily demean the human tumor-nude mouse model, but is well in line with the changes occurring with time in the human patient tumors. Many tumor characteristics appear to be stable in the nude mouse, and it has been shown that tumor markers and secretion of certain hormones may be maintained in the xenografts.

Ultrastructure of infection-thread development during the infection of soybean by Rhizobium japonicum.

Abstract: The location and topography of infection sites in soybean (Glycine max (L.) Merr.) root hairs spot-inoculated with Rhizobium japonicum have been studied at the ultrastructural level. Infections commonly developed at sites created when the induced deformation of an emerging root hair caused a portion of the root-hair cell wall to press against an adjacent epidermal cell, entrapping rhizobia within the pocket between the two host cells. Infections were initiated by bacteria which became embedded in the mucigel in the enclosed groove. Infection-thread formation in soybean appears to involve degradation of mucigel material and localized disruption of the outer layer of the folded hair cell wall by one or more entrapped rhizobia. Rhizobia at the site of penetration are separated from the host cytoplasm by the host plasmalemma and by a layer of wall material that appears similar or identical to the normal inner layer of the hair cell wall. Proliferation of the bacteria results in an irregular, wall-bound sac near the site of penetration. Tubular infection threads, bounded by wall material of the same appearance as that surrounding the sac, emerge from the sac to carry rhizobia roughly single-file into the hair cell. Growing regions of the infection sac or thread are surrounded by host cytoplasm with high concentrations of organelles associated with synthesis and deposition of membrane and cell-wall material. The threads follow a highly irregular path toward the base of the hair cell. Threads commonly run along the base of the hair cell for some distance, and may branch and penetrate into subjacent cortical cells at several points in a manner analagous to the initial penetration of the root hair.