Total cell kill

Concepts of Growth Fraction and Total Cell Kill... 

In HSCT, very high doses of chemotherapy with or without total-body radiation (TBI) are given in an attempt to potentiate leukemia cell kill. Hematopoiesis is restored by the infusion of stem cells harvested from an HLA-compatible donor, thereby rescuing the patient from the consequences of total aplasia.13 It is the most effective antileukemic therapy currently available. 

Myeloperoxidase is an extremely potent, antimicrobial protein that is present in neutrophils at up to 5% of the total cell protein. Its role in the killing of a wide range of bacteria, fungi, viruses, protozoa and mammalian cells (e.g. tumour cells) is well established from in vitro studies. It also plays an important role in the inactivation of toxins and the activation of latent proteases, as well as in other functions described in section 5.4.1. In view of this apparent central role in neutrophil function during host defence, one would think that any deficiencies in this enzyme would have disastrous consequences on the ability of the host to combat infections. Until the early 1980s, this key role for myeloperoxidase in host protection seemed substantiated by the extremely low incidence of reports of patients with deficiencies of this enzyme. Indeed, up to this time, only 15 cases from 12 families had been reported worldwide. Sometimes these patients were asymptomatic but often suffered Candida infections, particularly if their myeloperoxidase deficiency was also associated with diabetes mellitus. 

One possibility is that there is differential susceptibility to both mutation and killing among the cells. If, for example, there are two populations of cells, the high-dose data reflect the mutation rate of the component more resistant to killing. If these cells are also resistant to mutation, the resistance of the total cell population is underestimated. Another possibility is that there is a mutation-repair mechanism that is turned on at high doses. Deviations from either of these causes can usually be detected by the shape and slope of the curve at high doses for example, linear extrapolation from high-dose... 

Cytotoxicity Study. The cytoxicity study was carried out in order to evaluate the gross toxicity of polyethylene films widi phosphonyl dichloride and potassium phosphonate moieties present on the surface. The behaviour of fibroblasts seeded on these surfaces was compared with their behavior on materials surfaces whose toxicity is known. Polyethylene films coated with methyl cyanoacrylate were used as a positive control because it is well known that methyl cyanoacrylate has an extremely toxic effect on cells (10). The fibroblasts were kill within 24 hours of being placed on the positive control films. Photographs of the fibroblasts seeded on these positive control films are shown in Figure 3, exhibiting total cell death and lysis. 

The goal of sterilization is to kill (or physically remove) 100% of the living microorganisms and their various resistant reproductive spores (mold conidiospores, yeast ascospores, bacterial endospores) as well. This is different from sanitation, which is a production concept, whereby the total cell count is reduced to an acceptably low number (likely zero). Sterilization of laboratory media and equipment may utilize exposure to conditions of high temperature (boiling water), or combined high temperature and pressure (autoclave), toxic chemicals, or physical removal (filtration). 

Eosinophils, which constitute only 1 to 4% of the total number of white blood cells, are only weak phagocytes. These leukocytes are produced in large numbers in individuals with internal parasitic infections. The eosinophils attach to the parasites and secrete substances that kill them, including ... 

Inhalation route via cervical trachea ewes, 3-4 years old exposed to smoke containing high (but unknown) concentrations of acrolein for 20 min killed Within 24 h of exposure, there was total sloughing of cervical tracheal epithelium and a 35% reduction in tracheal basal cells trachea was normal 18-22 days after exposure 13... 

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