Perivenous cells

Figure 8.30 Different roles of periportal and perivenous cells in the liver in respect of glutamine metabolism. Glutamine is converted to glucose in periportal cells via gluconeogenesis in perivenous cells, ammonia is taken up, to form glutamine, which is released into the blood. This emphasises the importance of the liver in removing ammonia from the blood, i.e. if possesses two process to ensure that all the ammonia is removed.

This compartmentation of processes in the liver cells occurs with other pathways glycolysis occurs mainly in the perivenous cells whereas gluconeogenesis occurs mainly in the periportal cells (Chapter 6). 

Energy can likewise be generated by means of fructose and ethanol oxidation. The partial pressure of oxygen falls from 13 % (centroacinar) to 6 % (perivenous) due to progressive oxygen consumption. Thus it is here that hypoxic cell damage can most frequently be expected. 

As a rule, 2 mol bicarbonate are required for the synthesis of 1 mol urea. The amount of urea eliminated in the urine is approximately 500 mmol/day (ca. 30 g). Normally, only about 25% of the capacity of the urea cycle are used. It is therefore virtually impossible for hyperammonaemia to be a sequela to isolated NH4+ hyperproduction alone. In patients with liver cirrhosis, the capacity for urea synthesis is reduced by approximately 80%, i. e. there is a considerable decrease in ammonia detoxification in the periportal field, predominantly due to a function loss on the part of the perivenous scavenger cells. 

PER see Prohdn efficiency ratio Perilipirv 383,401 Periportal hepatocytes, 253 Perivenous hepatocytes, 253 Permeability, defined, 119 Pernicious anemia as cancer risk factor. 519 folic acid and, 516 parietal cells and, 83 vitamin Biz deficieiKy and, 434,518-519, 523... 

Cell therapy consists of the parenteral or enteral administration of cells or parts of cell obtained from animal organs and/or tissues from cattle, sheep, pigs, or rabbits. Two different types of cell preparations are in use fresh cells, which are administered in fresh form, and dried cells or so-called sicca cells, which are prepared for later use. The most prevailing risks of cell therapy are local and generalized allergic reactions (fever, nausea, vomiting, urticaria, and anaphylactic shock). Other untoward consequences include fatal and non-fatal encephalomyelitis, polyneuritis, Landry-Guillain-Barre sjmdrome, fatal serum sickness, perivenous leukoencephalitis, and immune-complex vasculitis. 

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