Tissue parenchyma

Figure 19.1 Physiological pharmacokinetic model for evaluating in vivo disposition of a macromolecular drug. (A) A multi-compartment model in which every tissue compartment is connected with the plasma pool by blood flow. (B) Tissue uptake of a drug from vascular space to tissue parenchyma.

Plants are predominantly composed of parenchyma and woody tissues. Parenchyma cells dominate the green tissues in leaves and are composed of a protein-rich protoplast surrounded by a cellulose wall. Woody plant cells dominate all support (sclerenchyma) and transport (xylem and phloem) stmctures in a plant. They are composed of several layers (middle lamella, primary wall, secondary wall, and tertiary wall) with varying proportions of cellulose, hemicellulose, and lignin (Fengel and Wegener, 1984). 

In addition to the identification of seeds, nuts, fruits, and tree species, the investigation of charred plant remains has recently advanced to the other tissue. In particular, SEM [Scanning Electron Microscope] studies have been able to identify charred parenchymous tissues. Parenchyma is the most common plant tissue and makes up the bulk of the primary plant body, including the leaves, flowers, roots, the pulp of fruits, and the pith of stems in woody plants. The thin-walled parenchyma cells have large empty spaces and distinctive intercellular areas (Fig. 5.3). 

Parenchymous tissues Parenchyma is plant storage tissue, commonly found in roots,... 

Patients with hypertension may develop damage to either the renal tissue (parenchyma) or the renal arteries. Chronic kidney disease presents initially as microalbuminuria (30-299 mg albumin in a 24-hour urine collection) that can progress to macroalbuminuria and overt kidney failure. The rate of kidney function deterioration is accelerated when both hypertension and diabetes are present. Once patients have an estimated glomerular filtration rate (GFR) of less than 60 mL/m per minute or macroalbuminuria, they have chronic kidney disease, and the risk of cardiovascular disease and progression to severe chronic kidney disease increases. Strict BP control to a goal of less than 130/80 mm Hg can slow the decline in kidney function. This strict control often requires two or more antihypertensive agents. 

The adaptation of tissue blood flow to local metabolic requirements is a dramatic example of the control of smooth muscle contraction by metabolic factors. The exact mechanisms involved are still not known with certainty, and in particular it is not clear how much is due to a direct response of the vascular smooth muscle to its chemical environment and how much is due to "vasodilator metabolites" released from the tissue parenchyma (Sparks, 1980). The possibility that structures other than smooth muscle cells, notably the endothelium, act as oxygen sensors is a further area for investigation. The emphasis here will be on studies relating the metabolic supply of smooth muscle and its contractile activity. 

The majority of the fluid that is filtered from the microcirculation into the interstitial space is carried out of the tissue via the lymphatic network. This unidirectional transport system originates with a set of blind channels in distal regions of the microcirculation. It carries a variety of interstitial molecules, proteins, metabolites, colloids, and even cells along channels deeply embedded in the tissue parenchyma toward a set of sequential lymph nodes and eventually back into the venous system via the right and left thoracic ducts. The lymphatics are the pathways for immune surveillance by the lymphocytes and thus, they are one of the important pathways of the immune system [Wei et al, 2003]. 

FIGURE 2.6 Dynamic susceptibility contrast imaging. Axial images of the brain are acquired repeatedly, in this case every 1.5 seconds. As a bolus of intravenously injected contrast material enters the brain, first arteries, then brain parenchyma, and finally veins demonstrate a transient loss of signal intensity. In this acute stroke patient, hypoperfusion of the left middle cerebral artery territory results in delayed arrival of the contrast bolus and prolonged stasis of contrast within the tissue. 

The neurointerventionalist should limit the number of microcatheter injections performed during the exam, as there is growing evidence that this may increase the chances of hemorrhagic transformation of the infarcted tissue. Direct injection of contrast into stagnant vessels, which contains injured glial cells and thus breakdown of the blood-brain barrier, allows for contrast extravasation. Contrast is readily visualized on the immediate post-thrombolysis CT as an area of high attenuation in the parenchyma. In some instances, MRI with susceptibility-weighted sequences may be useful to differentiate contrast extravasation from Such a distinction... 

Pectins from different tissue zones, namely epidermis, the outer parenchyma, the parenchyma of the Ccirpels zone, the carpels and the core line, were isolated firom alcohol-insoluble solids (AIS. In both zones of parenchyma, the cell-wall material represented about 80% of the total cell-wall material from the whole fruit. The pectins from the outer parenchyma accounted for 70% of the total. However, there was no change in galacturonic acid concentration. The enzymatic solubilisation of tissues or AIS was higher in the parenchyma zones than in the others. Nevertheless, the depolymerisation of the soluble pectins from parenchyma zones with an endopolygacturonase required the action of pectin methylesterase. The depoiymerisation of pectins from the other zones, however, did not. 

In apple processing, enzymatic treatment of the crushed fruit leads to a lower degree of degradation of the peel and the core than the rest of the fruit. Figure 1 shows the separate tissue zones in diagrammatic form. Their anatomic origins are different the epidermis and outer parenchyma zones are tissues derived from the fusion of the calyx, corolla and stamens of the flower the inner zones correspond to tissue derived from ovaries and carpels. The characterisation of the cell-wall material, especially pectins, from the different zones of the fruit may provide additional information on the possibility of finding uses for the discarded fractions. 

The outer parenchyma (B) is the major tissue zone of the fruit, corresponding to more than 80 % of dry matter and the edible zones (B and C) contained 80 % of the cell-wall material (Fig.2). 

The first assumption had been that there were two mechanisms involved in the degradation process. (Fig. 3) TTie first one was very fast (rate constant kj) affecting the peripheric part of the parenchyma (Mj) where most of the enzyme was initialy adsorbed. The second mechanism was slow (rate constant k2) for it affected the deeper zone of the tissue (M2) where the enzyme amount was low. 

Parenchyma The essential and distinctive cells or tissue of an organ (as distinguished from its supporting framework). 

The presence of blood in the brain parenchyma causes damage to surrounding tissue through a mass effect and the neurotoxicity of blood components and their degradation products. Compression of tissue surrounding hematomas may lead to secondary ischemia. Much of the early mortality of hemorrhagic stroke is due to an abrupt increase in intracranial pressure that can lead to herniation and death. 

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