Benjamin Y. Klein

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A growing body of evidence now supports the isolation of microorganisms from ancient materials. However, questions about the stringency of extraction methods and the genetic relatedness of isolated organisms to their closest living relatives continue to challenge the authenticity of these ancient life forms. Previous studies have successfully isolated a(More)
During growth on n-alkanes, the marine bacterium Marinobacter hydrocarbonoclasticus SP17 formed a biofilm at the alkane-water interface. We showed that hexadecane degradation was correlated with biofilm development and that alkane uptake is localized in the biofilm but not in the bulk medium. Biofilms were observed in cultures on metabolizable n-alkanes(More)
Bone marrow stromal cells contain colony forming cells with the potential to differentiate into osteoprogenitor (OPC) cells. OPC-stimulation medium, containing dexamethasone, ascorbate, and beta-glycerophosphate is widely used to recruit OPCs in culture. Cultures were incubated 24 h with rhodamine 123 (Rho), on different days, to examine the effect of the(More)
We present a model for isolating human cell culture derived from biopsies obtained during orthopedic surgery. Four donor groups were defined by gender and age: pre- and postmenopausal women (<50 and >55 years, respectively), and younger (30-55 years) and older (>60 years) men. Bone-derived cells were identified as osteoblasts by major osteoblastic(More)
The ability of Levamisole to decrease mineralization in skeletal tissue is usually related to its effect on alkaline phosphatase (ALP). However, Levamisole is also suspected to diminish mineralization by an additional mechanism which is unrelated to the ALP control of apatite crystal growth. To delineate the time in differentiation during which Levamisole(More)
Bone marrow stromal cells give rise to osteoprogenitor cell (OPC) colonies, with characteristic mineralized bone nodules in vitro. During differentiation, OPCs in the culture are surrounded by heterogeneous populations of various cell lineages and by different OPC differentiation stages. In the present study, attempts were made to increase the homogeneity(More)
Hexadecane assimilation by Marinobacter hydrocarbonoclasticus SP17 occurs through the formation of a biofilm at the alkane-water interface. In this study we focused on the interactions of cells with the alkane-water interface occurring during initiation of biofilm development. The behavior of cells at the interface was apprehended by investigating(More)
The act of chondrocyte preparation for primary, enchondral, mineralization is associated with a decline in mitochondrial respiration toward the end of the proliferative zone and the hypertrophic zone in the growth plate. Dexamethasone (Dex)-stimulated cultures of rat marrow stroma constitute a differentiation model simulating, in its energy metabolism,(More)
The inability of spontaneous and some laboratory-induced tumors to stimulate the immune system has continuously raised the question of the validity of using immunological maneuvers in order to control tumor growth. In this project we suggest that a tumor which is nonimmunogenic still has an immunogenic potential that can be revealed and used in order to(More)