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: RNA & Antigen. 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.

Ultrasmall targeted nanoparticles with engineered antibody fragments for imaging detection of HER2-overexpressing breast cancer

Abstract: Controlling the biodistribution of nanoparticles upon intravenous injection is the key to achieving target specificity. One of the impediments in nanoparticle-based tumor targeting is the inability to limit the trafficking of nanoparticles to liver and other organs leading to smaller accumulated amounts in tumor tissues, particularly via passive targeting. Here we overcome both these challenges by designing nanoparticles that combine the specificity of antibodies with favorable particle biodistribution profiles, while not exceeding the threshold for renal filtration as a combined vehicle. To that end, ultrasmall silica nanoparticles are functionalized with anti-human epidermal growth factor receptor 2 (HER2) single-chain variable fragments to exhibit high tumor-targeting efficiency and efficient renal clearance. This ultrasmall targeted nanotheranostics/nanotherapeutic platform has broad utility, both for imaging a variety of tumor tissues by suitably adopting the targeting fragment and as a potentially useful drug delivery vehicle.

Specific recruitment of protein kinase A to the immunoglobulin locus regulates class-switch recombination

Abstract: Immunoglobulin class-switch recombination (CSR) requires activation-induced cytidine deaminase (AID). Deamination of DNA by AID in transcribed switch (S) regions leads to double-stranded breaks in DNA that serve as obligatory CSR intermediates. Here we demonstrate that the catalytic and regulatory subunits of protein kinase A (PKA) were specifically recruited to S regions to promote the localized phosphorylation of AID, which led to binding of replication protein A and subsequent propagation of the CSR cascade. Accordingly, inactivation of PKA resulted in considerable disruption of CSR because of decreased AID phosphorylation and recruitment of replication protein A to S regions. We propose that PKA nucleates the formation of active AID complexes specifically on S regions to generate the high density of DNA lesions required for CSR.

The Ultrastructure of Synchronized Hela Cells

Abstract: Synchronous populations of mitotic HeLa cells were obtained by the controlled agitation method, and a detailed morphological study of the cells in all phases of the cell cycle was undertaken to correlate variations in cell structures to known coexisting biochemical events. Autoradiographic techniques using tritiated thymidine ( 3 H-TdR) were used to detect S cells, and colcemid was added to some G 2 samples to prevent the cells from going into the next cycle, thus preventing contamination with G 1 cells. The approximate duration (in hours) of the 4 phases were as follows: M = 1.4, G 1 = 8-9, S = 7, G 2 = 4, and the generation time ( T ) = 21 ± 2 h. Randomization of the cell populations became apparent in the G 2 phase (contaminated with S and M cells) and was most likely a result of the genetic make-up of the individual (mixoploid) HeLa cells, nutritional factors (serum lots used), temperature shock, and handling effects. Polyribosomes shifted to monomeric ribosomes during late prophase, at which time nucleoli also break down. These changes are correlated with the drop in protein and RNA synthesis reported for mitotic mammalian cells. The Golgi apparatus persisted in a modified form throughout mitosis. The mid-body forms from the anaphase stem-body and may interfere with the separation of daughter cells. Our studies suggest that the mid-body goes to one of the daughter cells where remnants of this structure were seen in early G 1 cells. Large numbers of polyribosomes and the presence of well-developed nucleoli (many attached to the nuclear envelope) characterized G 1 . These structures, which play a major role in protein and RNA synthesis, persist with slight variations throughout interphase. Dense fibrillar nuclear bodies were prominent in late G 1 cells. Centrioles separate during G 1 , and replicate by orthogonal budding during the S phase. Reproducible labelling patterns which reflect the asynchronous multireplicon nature of DNA synthesis in mammalian cells were characteristic of the various stages of the S phase. Granular nuclear bodies, which were prominent in S and G 2 cells, may correspond to the larger species of heterogeneous nuclear RNA found in HeLa cells. G 2 cells were similar in appearance to S cells. As heterochromatin areas increased in late G 2 and prophase, perichromatin granules (of unknown significance) became prominent. Mitochondria behaved as independent cell organelles throughout the cell cycle. Hypertrophied RER, SER, and annulate lamellae, characterized the cytoplasm of colcemidtreated cells. The above changes are indicative of increased metabolic activity, and these structures may function in the production of colcemid-detoxify enzymes in a manner analogous to that of drug-treated hepatocytes, such as those treated with phenobarbital.