A tissue levels

The free component of plasma cortisol is biologically active and is filtered and excreted in the urine, where it can be measured. It would appear that urinary free cortisol estimations may give a more accurate picture of glucocorticoid activity at a tissue level than most other measurements. 

At the early stage of the development of the heart-on-a-chip, a PDMS microfluidic network was combined with planar electrode array to measure the extracellular potential from individual adult cardiomyocytes [54]. Another microfluidic device with an array of electrodes was developed to electrically measure the metabolic profile of cardiomyocytes and optically measure cell contractility [55]. Grosberg et al. first introduced a tissue level heart-on-a-chip to measure the contractility of neonatal cardiac muscle tissue [52]. In the design, eight muscular thin films (MTF) were fabricated on a chip. A layer of poly(N-isopropylacrylamide) (PIPAAm) dissolved at below 35 °C is spin-coated on top of a glass slide (Fig. 5A). Subsequently, a PDMS layer was coated on top of the PIPAAM layer. The PDMS layer was used to seed neonatal rat ventricular cardiomyocytes. The substrate seeded with cells is placed in the bath and the film layers were manually cut to fabricate an array of two opposite rows of four rectangular film layers of MTFs. The MTFs are peeled off after PIPAAm is dissolved as a solution when kept below 35 °C. Finally, electrodes are placed on the top and the bottom of MTFs. 

Histopathology Subdiscipline of histology that focuses on development of disease at a tissue level. It uses biopsies to diagnose and evaluate disease progression. 

On the contrary in more severe conditions of iodine deficiency, a failure of these adaptative mechanisms frequently occurs. This failure is evidenced by the biological demonstration of hypothyroidism (10). Experimental studies have confirmed that low serum T4 and high TSH serum concentrations observed in severely iodine deficient rats indicate overt hypothyroidism at a tissue level, in spite of normal serum T3 levels (12). 

Dihydroxyvitamin (283) is the endogenous ligand for the vitamin receptor (VDR). It modulates genomic function in a tissue and developmentaHy specific manner and affects ceU proliferation, differentiation, and mineral homeostasis (74). Vitamin mobilizes calcium from the bone to maintain plasma Ca " levels. Vitamin and VDR are present in the CNS where they may play a role in regulating Ca " homeostasis. Vitamin D has potent immunomodulatory activity in vivo. 

In humans, thiamine is both actively and passively absorbed to a limited level in the intestines, is transported as the free vitamin, is then taken up in actively metabolizing tissues, and is converted to the phosphate esters via ubiquitous thiamine kinases. During thiamine deficiency all tissues stores are readily mobilhed. Because depletion of thiamine levels in erythrocytes parallels that of other tissues, erythrocyte thiamine levels ate used to quantitate severity of the deficiency. As deficiency progresses, thiamine becomes indetectable in the urine, the primary excretory route for this vitamin and its metaboHtes. Six major metaboHtes, of more than 20 total, have been characterized from human urine, including thiamine fragments (7,8), and the corresponding carboxyHc acids (1,37,38). 

At a cellular level, the activation of mAChRs leads to a wide spectrum of biochemical and electrophysiological responses [1, 5]. The precise pattern of responses that can be observed does not only depend on the nature of the activated G proteins (receptor subtypes) but also on which specific components of different signaling cascades (e.g. effector enzymes or ion channels) are actually expressed in the studied cell type or tissue. The observed effects can be caused by direct interactions of the activated G protein(s) with effector enzymes or ion channels or may be mediated by second messengers (Ca2+, DP3, etc.) generated upon mAChR stimulation. 

The process whereby cellular and tissue levels of one or more cytochrome P450 enzymes are increased in response to treatment of cells, or a whole organism,... 

Perifascicular capillaries are closer to aggregates of antibody-secreting cells (B-lymphocytes) situated in perimysial connective tissue and therefore are most severely affected by antibody-dependent cytotoxic reactions. Immune-complex deposition occurs at a higher level in the vascular tree (i.e., at arteriolar level) and this may cause fluctuations in perfusion pressure. Perifascicular capillaries are most distal from the head of vascular pressure and therefore most likely to suffer from periodic anoxia. 

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