Calf thymus lymphocytes

Thymic factors are naturally occurring substances that promote T-lymphocyte differentiation and differentiation of early stem cells into prothymocytes. Each of the available preparations (e.g., thymic humoral factor, thymosin fraction 5, and thymodulin) are mixtures of several polypeptides isolated from a calf thymus extract. 

Acetaldehyde caused DNA strand breaks and cross-links in human lymphocytes in vitro without metabolic activation, but not in human bronchial epithelial cells and in human leukocytes. It has been shown to bind covalently to deoxynucleotides in vitro to form DNA-protein cross-links in rat nasal mucosa. Acetaldehyde-DNA adducts have been found in vitro in calf thymus DNA, in 2 -dcoxyguanosinc-3 -monophosphatc and in liver from mice treated with ethanol (Fang Vaca, 1995). Abnormal sperm morphology or spennocyte micronuclei were not observed in mice treated with an intraperitoneal injection of acetaldehyde. 

The pulmonary oedema produced in rats by dehydromonocrotaline has been studied by electron microscopy. Tritiated dehydroretronecine has been used in studies of the binding of this metabolite to macromolecules. Studies in vivo with rhesus monkeys revealed preferential binding of dehydroretronedne to the protein of gastric mucosa. Much less radioactivity was found associated with RNA and DNA. Binding in vitro to calf thymus DNA and bovine serum albumin took place most readily under acidic conditions. Tritiated dehydroheliotridine has been used to study the preferential depression of satellite DNA synthesis by this metabolite in cultured sheep lymphocytes and ovine kidney cells. The mechanism of the antimitotic action of lasiocarpine and dehydroheliotridine has been investigated in... 

Thymosin, Cell free, lymphocytopoietic hormone and biologically active thymic factor, comprising a family of acidic, heat-stable polypeptides, that plays an important part in the development of T-cells (thymus-dependent lymphocytes) and immunological functions in animals and man. Extraction from calf thymus and partial purification A. L. Goldstein er al. Proc. Nat Acad. Scl USA 56, 1010 (1966). Purification and characterization of thymosins and isotn of one of the active components, thymosin /ruction 5 eidem, ibid. 69, 1800 (1972). Improved isoln and properties J. A. Hooper et al. Ann. N.Y. Acad. Scl 249, ]25 (1975). 

All the multiple forms of calf intestinal adenosine deaminase as well as those of calf thymus, calf thymocytes, and human erythrocytes and lymphocytes are inactivated by this reagent. ... 

The usual source of TDTase is the calf thymus gland. It contains 5-10 mg of TDTase per kg of fresh tissue. The enzyme is also found at high levels (100—200 U/10 cells) in certain leukemic lymphocytes (e.g., human leukemia Molt-4 and mouse thymoma PI 798) and at a detectable level in bone marrow. TDTase activity is not found in prokaryotes nor in unicellular eukaryotes. 

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