Oxygen Carriers (“Blood Substitutes”)Raison d'Etre, Chemistry, and Some Physiology Blut ist ein ganz besondrer Saft1

Excessive activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor has been implicated in the sequence of neurochemical events that results in irreversible neuronal damage in cerebral ischemia. The effects of the NMDA antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) upon the amount of ischemic brain damage has been assessed quantitatively in the lightly anesthetized rat. Focal cerebral ischemia was produced by the permanent occlusion of one middle cerebral artery (MCA), and the animals were killed 3 hours after the arterial occlusion. MK-801 (0.5 mg/kg) was administered intravenously either 30 minutes prior to MCA occlusion or 30 minutes after the induction of ischemia. Pretreatment with MK-801 reduced the volume of ischemic damage both in the cerebral cortex (by 38% compared with untreated rats with MCA occlusion; p less than 0.01) and in the caudate nucleus (by 18% compared with controls; p less than 0.05). Treatment with MK-801, initiated 30 minutes after MCA occlusion, reduced the volume of ischemic damage in the cerebral cortex (by 52% compared with controls; p less than 0.01). The volume of ischemic damage in the caudate nucleus was minimally influenced by MK-801 treatment initiated after MCA occlusion. The antiischemic effects of MK-801 were readily demonstrable despite the hypotension that MK-801 induced in rats anesthetized with halothane (0.5%), nitrous oxide (70%), and oxygen (30%). The potency of MK-801 in reducing ischemic brain damage, even when administered after the induction of ischemia, highlights the potential use of NMDA receptor antagonists for the treatment of focal cerebral ischemia in humans.

The glutamate antagonist MK-801 reduces focal ischemic brain damage in the rat.

▪ Abstract The recent rapid increase in interest in tomographic imaging of small animals and of human (and large animal) organ biopsies is driven largely by drug discovery, cancer detection/monitoring, phenotype identification and/or characterization, and development of disease detection methods and monitoring efficacies of drugs in disease treatment. In biomedical applications, micro-computed tomography (CT) scanners can function as scaled-down (i.e., mini) clinical CT scanners that provide a three-dimensional (3-D) image of most, if not the entire, torso of a mouse at image resolution (50–100 μm) scaled proportional to that of a human CT image. Micro-CT scanners, on the other hand, image specimens the size of intact rodent organs at spatial resolutions from cellular (20 μm) down to subcellular dimensions (e.g., 1 μm) and fill the resolution-hiatus between microscope imaging, which resolves individual cells in thin sections of tissue, and mini-CT imaging of intact volumes.

Micro-computed tomography - Current status and developments

The effects of the glutamate N-methyl-D aspartate (NMDA) receptor antagonist, MK-801, upon ischemic brain damage has been examined in anesthetized cats. Focal cerebral ischemia was produced by permanent occlusion of one middle cerebral artery and the animals were killed 6 h later. The amount of early ischemic damage was assessed in coronal sections at 16 predetermined stereotactic planes. Pretreatment with MK-801 (5 mg/kg, i.v.), 30 min before occlusion of the middle cerebral artery significantly reduced the volume of ischemic damage (from 32.7 ± 4.0% of the cerebral hemisphere in vehicle-treated cats to 16.2 ± 4.5% in MK-801-treated cats). NMDA receptor antagonists that penetrate the blood-brain barrier, such as MK-801, merit further study as protective agents against ischemic brain damage.

https://journals.sagepub.com/doi/pdf/10.1038/jcbfm.1988.18

Protective effect of the glutamate antagonist, MK-801 in focal cerebral ischemia in the cat.

Despite the resounding clinical success in cancer treatment of antibodies that block the interaction of PD1 with its ligand PDL11, the mechanisms involved remain unknown. A major limitation to understanding the origin and fate of T cells in tumour immunity is the lack of quantitative information on the distribution of individual clonotypes of T cells in patients with cancer. Here, by performing deep single-cell sequencing of RNA and T cell receptors in patients with different types of cancer, we survey the profiles of various populations of T cells and T cell receptors in tumours, normal adjacent tissue, and peripheral blood. We find clear evidence of clonotypic expansion of effector-like T cells not only within the tumour but also in normal adjacent tissue. Patients with gene signatures of such clonotypic expansion respond best to anti-PDL1 therapy. Notably, expanded clonotypes found in the tumour and normal adjacent tissue can also typically be detected in peripheral blood, which suggests a convenient approach to patient identification. Analyses of our data together with several external datasets suggest that intratumoural T cells, especially in responsive patients, are replenished with fresh, non-exhausted replacement cells from sites outside the tumour, suggesting continued activity of the cancer immunity cycle in these patients, the acceleration of which may be associated with clinical response. Large-scale single-cell sequencing of RNA and T cell receptors in samples from patients with cancer shows clonotypic expansion of effector-like T cells not only in tumour tissue but also in normal adjacent tissues and peripheral blood, which associates with clinical response to cancer immunotherapy.

Peripheral T cell expansion predicts tumour infiltration and clinical response

Global hemispheric ischemia was produced in cats by bilateral carotid ligation and bleeding to a mean arterial pressure of 30 +/- 2 (SE) mm Hg. Total electrocerebral silence, as determined by computer-based power analysis, was obtained and maintained for 15 minutes. After this severe cerebral ischemic episode, the heparinized blood was reinfused and the carotid clamps were removed. After the cerebral ischemia, the ventriculosubarachnoid space was perfused with an oxygenated fluorocarbon nutrient solution (OFNS) or modified Elliott's B solution (ES) (control perfusion). The OFNS perfusate contained 400 to 640 mm Hg pO2 (produced by means of a bubble oxygenator pump system) as well as electrolytes, glucose, and amino acids, all of which are known to be important in cerebral metabolism. Flow rates of the perfusion were maintained at either 3 or 6 ml/minute and intracranial pressures were never permitted to exceed 10 mm Hg. During passage through the ventriculosubarachnoid space, oxygen, carbon dioxide, and electrolytes were exchanged between the brain and the OFNS perfusate. In addition, the OFNS perfusate was capable of picking up pCO2, lactate, and pyruvate. This produced a significant return of electrocerebral activity (P less than 0.01) and oxidative metabolism (P less than 0.01), as evidenced by a decline in the lactate/pyruvate ratio in the OFNS-treated cats, but not in nonperfused animals or those perfused with ES. In this study the ventriculosubarachnoid system served as an alternate vascular tree and enabled the perfusate to accomplish many of the functions of blood. Substantial penetration of the perfusate products into the brain occurred, enabling oxidative metabolism, removal of waste products, and electrocerebral activity to be reestablished.

Severe cerebral ischemia treatment by ventriculosubarachnoid perfusion with an oxygenated fluorocarbon emulsion.

Focal cerebral ischemia: reduction in size of infarcts by ventriculo-subarachnoid perfusion with fluorocarbon emulsion.

Effects of organochlorine insecticides on the toxicity and in vitro plasma detoxication of paraoxon.

A decreased rate of biliary excretion of radioactive metabolites of 3,4-benzopyrene was observed in rats given a single dose of nicotine. Prior treatment of rats with nicotine decreased benzopyrene hydroxylase activity in homogenates of liver, lung, and small intestine. The addition of nicotine to incubated tissues also decreased benzopyrene hydroxylase activity. These findings show that nicotine inhibits the metabolism of 3,4-benzopyrene in vivo and in vitro.

https://science.sciencemag.org/content/sci/184/4141/1081.full.pdf

Nicotine Inhibition of the Metabolism of 3,4-Benzopyrene, a Carcinogen in Tobacco Smoke

Trifluralin, a widely used herbicide, added to the diet before the p.o. administration of benzo( a )pyrene (BP) and fed continuously, significantly inhibited the induction of lung and forestomach tumors in female A/J mice. Dietary intake of trifluralin before the administration of BP resulted in a significant increase in glutathione in lung and forestomach but not in liver and glandular stomach. Trifluralin treatment also inhibited the binding of [3H]BP to liver and lung DNA, as well as to protein in the liver. Under these conditions, the protection against BP-induced lung tumors and perhaps forestomach tumors may be due to an elevation of tissue glutathione, resulting in a decreased binding of reactive metabolites of BP to macromolecules at these sites. The results indicate that trifluralin has a “blocking” effect in its inhibition of BP-induced tumors.

Our studies show that trifluralin also inhibits chemical carcinogenesis in lung and forestomach when started in the diet 1 day after the administration of BP and fed continuously thereafter. In the case of lung, although maximum inhibition of tumors occurred when trifluralin was started 1 day after BP, there was significant protection at all time intervals (0 to 7 days) against lung tumors. The finding that trifluralin protects against BP tumorigenesis when started in the diet after the administration of the carcinogen clearly demonstrates that trifluralin also has a “suppressive” effect against BP-induced tumors.

Anthony J. Triolo

Papers

Severe cerebral ischemia treatment by ventriculosubarachnoid perfusion with an oxygenated fluorocarbon emulsion.

Focal cerebral ischemia: reduction in size of infarcts by ventriculo-subarachnoid perfusion with fluorocarbon emulsion.

Effects of organochlorine insecticides on the toxicity and in vitro plasma detoxication of paraoxon.

Nicotine Inhibition of the Metabolism of 3,4-Benzopyrene, a Carcinogen in Tobacco Smoke

Protective effects of trifluralin on benzo(a)pyrene-induced tumors in A/J mice.