A methemoglobin-dependent and plasma-stimulated experimental model of oxidative hemolysis

Incubation of human red blood cells with ter-butyl hydroperoxide (tBHP) causes depletion of GSH and the production of highly reactive oxygen derivatives, notably hydroxyl (OH^?) radicals, followed by lysis of the cells. These effects are related to the formation of methemoglobin (MetHb), which catalyzes the homolytic cleavage of tBHP to form OH^? radicals. Lysis of red blood cells is the result of lipid peroxidation of membrane components and formation of protein aggregates and is enhanced if the tBHP-treated cells are resuspended in autologous plasma or serum. The tBHP-treated cells provide a useful model for analysis of the sequence of events in oxidative hemolysis.     

Cytochrome P-450 from mitochondria of bovine adrenal cortex Comparison of cholesterol side-chain cleavage P-450 with steroid 11β-hydroxylation P-450 and immunochemical cross-reactivity between adrenal mitochondrial and liver microsomal cytochromes P-450

Adrenocortical mitochondrial cytochrome P?450 specific to the cholesterol side-chain cleavage (desmolase) reaction differs from that for the 11β-hydroxylation reaction of deoxycorticosterone. The former cytochrome appears to be more loosely bound to the inner membrane than the latter. Upon ageing at 0°C or by aerobic treatment with ferrous ions, the desmolase P-450 was more stable than the 11β-hydroxylase P-450. By utilizing artificial hydroxylating agents such as cumene hydroperoxide, H₂O₂, and sodium periodate, the hydroxylation reaction of deoxycorticosterone to corticosterone in the absence of NADPH was observed to a comparable extent with the reaction in the presence of adrenodoxin reductase, adrenodoxin and NADPH. However, the hydroxylation reaction of cholesterol to pregnenolone was not supported by these artificial agents.Immunochemical cross-reactivity of bovine adrenal desmolase P-450 with rabbit liver microsomal P-450_LM4 was also investigated. We found a weak but significant cross-reactivity between the adrenal mitochondrial P-450 and liver microsomal P-450_LM4, indicating to some extent a homology between adrenal and liver cytochromes P-450.     

Targeting protein kinases benefits cancer immunotherapy

Small-molecule kinase inhibitors have been well established and successfully developed in the last decades for cancer target therapies. However, intrinsic or acquired drug resistance is becoming the major barrier for their clinical application. With the development of immunotherapies, in particular the discovery of immune checkpoint inhibitors (ICIs), the combination of ICIs with other therapies have recently been extensively explored, among which combination of ICIs with kinase inhibitors achieves promising clinical outcome in a plethora of cancer types. Here we comprehensively summarize the potent roles of protein kinases in modulating immune checkpoints both in tumor and immune cells, and reshaping tumor immune microenvironments by evoking innate immune response and neoantigen generation or presentation. Moreover, the clinical trial and approval of combined administration of kinase inhibitors with ICIs are collected, highlighting the precise strategies to benefit cancer immune therapies.     

Biochemical evidence for chemical and/or topographic differences in the lipoperoxidative processes induced by CCl4 and iron

Isolated rat hepatocytes, treated with CCl4 or ADP-Fe3+ complex show an enhanced lipid peroxidation and a decreased glucose 6-phosphatase activity. Lipid peroxidation is much more stimulated by ADP-Fe3+ or Fe3+ than by CCl4, when the metal and the haloalkane are used at a similar concentration. Increasing rates of lipid peroxidation in the different experimental conditions do not correlate with the degree of glucose 6-phosphatase inactivation, which is produced by CCl4 and not by a similar amount of ferric iron. In the case of iron, its intracellular concentration must be higher to give the enzyme inactivation exerted by CCl4. Higher intracellular levels of iron are reached when the metal is added to the cell suspension together with ADP. Under these conditions there is inactivation of glucose 6-phosphatase. Possible mechanisms accounting for a different enzyme sensitivity to iron and CCl4 are discussed.