Role of nerve growth factor in oxidant homeostasis: glutathione metabolism

Free radicals are generated in the CNS by ongoing oxygen metabolism and biological events associated with injury and inflammation. Increased free radical levels may also persist in some chronic neurological diseases and in the aged. Nerve growth factor (NGF) is a member of the neurotrophin family of proteins that can regulate neuronal development, maintenance, and recovery from injury. NGF protected rat pheochromocytoma PC12 cells, an adrenal chromaffin-like NGF-responsive cell line, from the oxidant stress accompanying hydrogen peroxide treatment by stimulating GSH levels and enzymes in the GSH metabolism cycle and in the GSH/GSH peroxidase antioxidant redox system, a ubiquitous cellular antioxidant system. Specifically, NGF increased gamma-glutamylcysteine synthetase (GCS) activity, the rate-limiting enzyme for GSH synthesis, by 50% after 9 h and GSH levels by 100% after 24 h of treatment. NGF stimulated GSH peroxidase by 30% after 3 days and glucose 6-phosphate dehydrogenase by 50% after 2 days. Treatment with NGF and cycloheximide, or actinomycin D, which inhibit protein and RNA synthesis, respectively, blocked the NGF stimulation of GCS and glucose 6-phosphate dehydrogenase. Increased GSH levels due to NGF treatment were responsible for the significant protection of PC12 cells from hydrogen peroxide-induced stress. Pretreatment of PC12 cells with NGF for 24 h rescued cells from the toxic effects of the extracellular hydrogen peroxide generated by the glucose/glucose oxidase system but did not rescue cells that were subjected to GSH deprivation due to treatment with 10 microM L-buthionine-(S,R)-sulfoximine, an inhibitor of GCS.(ABSTRACT TRUNCATED AT 250 WORDS)

Tunable dual-wavelength continuous-wave diode laser operated at 830 nm

An external grating cavity semiconductor diode laser is made to operate simultaneously at two separately adjustable wavelengths. Lasing is restricted to the vicinity of the solitary laser 6talon resonances.

Tunable external cavity diode laser that incorporates a polarization half-wave plate

The threshold current and specttal properties of a grating tuned external cavity semiconductor laser are improved by utilizing an intracavity half-wave plate to optimize the grating feedback.

Production of hybrid bispecific antibody recognizing human colorectal carcinoma and CD3 antigen

The present study reports on the use of gene transfer by vector DNA in the generation of hybrid hybridoma, the quadroma secreting the hybrid bispecific antibody. A quadroma B72.3neo/OKT3gpt was simply derived from the fusion of two hybridoma cell lines, B72.3 and OKT3, tagged with vector DNA mpSV2neo and mpSV2gpt, respectively, and selected in the media containing both G418 and mycophenolic acid. The hybrid bispecific antibody B72.3/OKT3 was purified from the quadroma ascites by the use of hydroxylapatite column on high-pressure liquid chromatography. This bispecific antibody contained one binding site for the TAG72 antigen on OVCAR3 tumor cells and the other binding site for the CD3 molecule on human T cells. It was able to target human T lymphocytes to significantly lyse the human ovarian cancer cells and may therefore be useful in immunotherapy of cancer.

[The determination and evaluation of the plasma amino acid in respiratory failure]

The measurement of the plasma amino acid was made in 15 patients with chronic respiratory failure and 15 persons of control. The results showed: (1) The plasma acid model changed. Lysine increases and arginine decreases, due to hypothermia. Hypercapnia imbalance of acid and alkali and changes of hepatic dysfunction etc. (2) The prognosis of respiratory failure as well as its severity was judged according to the decreasing extent of arginine and BCAA. The more worse the condition of the disease, the more lowering of the level of arginine and BCAA. (3) The changes of blood gas analysis and hepatic dysfunction may effect on the metabolism of plasma amino acid in some degree. (4) Hypoxemia in infected patients with respiratory failure may cause peripheral deficit of energy. We suggested that patients should be given BCAA and arginine for more energy as anti-infection and oxygen therapy were used.

[Effects of stenosis on blood flow in the coronary artery of dogs]

The effects of stenosis on coronary blood flow (CBF) were studied in 22 open-chest mongrel dogs. A progressive stenosis was produced by a micrometer constrictor on the left circumflex coronary artery. Mean aortic pressure (Pa), distal coronary pressure (Pc) and stenotic segment pressure drop (delta P) were measured. Curve of CBF versus % stenosis showed that CBF was relatively constant with stenosis less than 85%, CBF rapidly decreased with stenosis of 85-95%, and then slowly reduced as stenosis was further increased. The change in CBF versus % stenosis was expressed as follows: CBF = 1.48 X 10(10) theta -27.6 A (where A = % stenosis in lumen area). With progressive coronary artery stenosis (greater than 75%), the change in percent stenosis and Pc showed a negative correlation: Pc = 159.1-1.36A (r = -0.73, P less than 0.01); the change in Pc and CBF showed a positive correlation: Pc = 16.9 + 1.3 CBF (r = 0.74, P less than 0.01).

Structural asymmetry in the CTP-liganded form of aspartate carbamoyltransferase from Escherichia coli

The protein and solvent structure of the CTP-liganded form of aspartate carbamoyltransferase from Escherichia coli yields an R-factor of 0.155 for data to a resolution of 2.6 A. The model has 7353 protein atoms, 945 sites for solvent, and two molecules of CTP. A total of 25 of the 912 residues of the model exist in more than one conformation. The root-mean-square deviation of bond lengths and angles from their ideal values is 0.013 A and 2.1 degrees, respectively. The model reported here reflects a correction in the trace of the regulatory chain. One molecule of CTP binds to each of the two regulatory chains of the asymmetric unit of the crystal. The interactions between the pyrimidine of each CTP molecule and the protein are similar. The 4-amino group of CTP binds to the carbonyl groups of residues 89 (tyrosine) and 12 (isoleucine) of the regulatory chain. The nitrogen of position 3 of the pyrimidine binds to the amide group of residue 12; the 2-keto group binds to lysine 60. The 2'-OH group of the ribose forms hydrogen bonds with lysine 60 and the carbonyl group of residue 9 (valine). The binding of the phosphate groups of CTP to the regulatory chain probably reflects an incomplete association of CTP with the enzyme at pH 5.8. A lattice contact influences the interaction between the triphosphate group of one CTP molecule and the protein. For the other CTP molecule, only lysine 94 binds to the phosphate groups of CTP. Of the two regulatory and two catalytic chains of the asymmetric unit of the crystal, there are only two significant violations of non-crystallographic symmetry. The active site in the vicinity of arginine 54 of one catalytic chain is larger than the active site of its non-crystallographic mate. The "expanded" cavity accommodates four solvent molecules in the vicinity of arginine 54 as opposed to two molecules of water for the "contracted" cavity. Furthermore, arginine 54 in the "expanded" pocket adopts two conformations, either hydrogen-bonding to glutamate 86 or to the phenolic oxygen atom of tyrosine 98; residues 86 and 98 are in a catalytic chain related by 3-fold symmetry to the catalytic chain of arginine 54. In the "contracted" pocket, arginine 54 binds only to glutamate 86.(ABSTRACT TRUNCATED AT 400 WORDS)