Intact tissue cellular studies

CELLULAR STUDIES IN INTACT TISSUE 8.2.1 Whole-Animal Studies... 

Nonpulsatile optical spectroscopy has been used for more than half a century for noninvasive medical assessment, such as in the use of multiwavelength tissue analysis for oximetry and skin reflectance measurement for bilirubin assessment in jaundiced neonates. These early applications have found some limited use, but with modest impact. Recent investigations into new nonpulsatile spectroscopy methods for assessment of deep-tissue oxygenation (e.g., cerebral oxygen monitoring), for evaluation of respiratory status at the cellular level, and for the detection of other critical analytes, such as glucose, may yet prove more fruitful. The former applications have led to spectroscopic studies of cytochromes in tissues, and the latter has led to considerable work into new approaches in near-infrared analysis of intact tissues. 

Cell-surface and intracellular j8-(l -> 4)-D-glucan synthase activities have been measured in connection with studies of the stage and direction of cell growth in Pisum sativum. An examination of membrane preparations of hormone-treated epicotyls of P. sativum has indicated that cellulose synthases in the Golgi and endoplasmic reticulum are not themselves loci for cellulose synthesis in vivo, but represent enzymes in transit to sites of action at the wall-protoplast interface, where they appear to operate only if the integrity of the cellular or nization is maintained. The initial rate of transfer of D-glucose from UDP-D-P C]glucose approached the observed rate of deposition in vivo of cellulose in intact tissues. 

Ad. 4. Alteration of anatomical features. Finally, several studies have attempted to manipulate the macroscopic features of muscle/meat tissue in order to verify or disprove the intra-/extra-cellular model. Efforts have been made to disrupt cell membranes by glycerination and DMSO treatment in order to make assessment of the potential role of membranes possible.30,40,41 All these studies showed unaltered relaxation behaviour upon membrane disintegration, which suggests that intact cell membranes in themselves are not necessary for a non-mono-exponential relaxation. Irrelevance of membranes... 

The parenchymatous liver cells (hepatocytes) hold a key position in the overall metabolism of iron (57, 58, 59, 60), and since functionally intact liver mitochondria can be conveniently prepared at high yield, these mitochondria have been most extensively studied so far. The iron transporting system discussed above for liver mitochondria is present also in mitochondria from other tissues and animal species (Table III). Quantitatively, erythroid cells of the bone marrow play the most important role in the overall metabolism of iron (61), and it was therefore not unexpected to find that the energized uptake of iron by isolated reticulocyte mitochondria exceeds that of mitochondria isolated from, for example, liver, kidney, and heart (Table IV). Thus, a relationship appears to exist between the rate and extent of heme protein turnover in mitochondria isolated from different tissues and their energized iron accumulation (30). Thus, it is evident that cellular differentiation is expressed at the mitochondrial level by modulation of the activity of essential functions related to iron transport and heme biosynthesis. 

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