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At least 559 records · Page 31Linked to original sources
PubMed2005

Differential gene expression of insulin receptor isoforms A and B and insulin receptor substrates 1, 2 and 3 in rat tissues: modulation by aging and differentiation in rat adipose tissue.

The insulin receptor (IR) occurs as two alternatively spliced isoforms, IR-A (exon 11-) and IR-B (exon 11+), which exhibit functional differences and are expressed in a tissue-specific manner. The IR substrate (IRS) proteins 1, 2 and 3 also differ in function and tissue distribution. Here we show the differential gene expression of IRs and IRSs in several rat target tissues of insulin action. IR-B is significantly higher than IR-A in epididymal white adipose tissue and adipogenesis induces a shift in the alternatively spliced species of IR from the A to the B isoform. Moreover, since aging in the rat is associated with the development of insulin resistance we looked for alterations of expression of these proteins in adipocytes from old rats. Our results reveal that there is a specific decrease in the expression of the IR-B isoform, as well as both mRNA and protein levels of IR, IRS-1 and IRS-3 being significantly decreased, in epididymal adipose tissue from old compared with adult rats. It is concluded that the down-regulation of early components of the insulin transduction pathway in a primary insulin target tissue could be related to the insulin resistance of aging.

Adipose Tissue↗
PubMed1985

Time dependence of insulin action in muscle and adipose tissue in the rat in vivo. An increasing response in adipose tissue with time.

The relative time dependency of enhancement of glucose metabolism by insulin in individual tissues has not been examined previously in vivo. Using the glucose clamp technique in the rat combined with radiolabeled 2-deoxyglucose (3H or 14C-2DG) administration, we have estimated a glucose metabolic index (Rg') in major insulin-sensitive tissues at two different times (between 40-55 min and 80-95 min) after onset of hyperinsulinemia (insulin levels of approximately 130 mU/L). At the completion of the clamp (125 min), eight different skeletal muscles and three different adipose tissue beds were rapidly removed for estimation of Rg', based on the accumulation of intracellular tracer 2DG-6-phosphate (2DGP). Insulin-stimulated Rg' was 60-70% higher at 80-95 min than at 40-55 min after elevation of insulin levels in all three adipose tissue beds (P less than 0.01). In contrast, insulin-stimulated whole body glucose utilization and Rg' in all skeletal muscles were not significantly different at these two times. The constancy of insulin action in skeletal muscles during the 2-h euglycemic clamp, as determined in these studies, does not support the concept that the glucose clamp represents an integral of many rapidly changing individual tissue responses. In conclusion, while the amount of insulin-stimulated glucose uptake in adipose tissue is low compared with muscle, the fraction increases with duration of insulin elevation. This effect may have significant implications in hyperinsulinemic states.

Adipose Tissue↗
PubMed1997

Counterregulation in peripheral tissues: effect of systemic hypoglycemia on levels of substrates and catecholamines in human skeletal muscle and adipose tissue.

We used microdialysis to distinguish the effects of hyperinsulinemia and hypoglycemia on glucose, gluconeogenic substrate, and catecholamine levels in adipose and muscle extracellular fluid (ECF). Ten lean humans (six males and four females) were studied during baseline and hyperinsulinemic (3 mU x kg-1 x min-1 for 3 h) euglycemia (5.0 mmol/l) and hypoglycemia (2.8 mmol/l). In muscle and adipose, basal ECF glucose was lower (muscle, 3.5 +/- 0.2 mmol/l; adipose tissue, 3.3 +/- 0.2 mmol/l) and lactate was higher (muscle, 2.2 +/- 0.2 mmol/l; adipose, 1.5 +/- 0.3 mmol/l) than respective plasma values (glucose, 4.9 +/- 0.1 mmol/l; lactate, 0.7 +/- 0.1 mmol/l), whereas alanine was higher in muscle ECF (379 +/- 22 micromol/l) than adipose tissue (306 +/- 22 micromol/l) and plasma (273 +/- 33 micromol/l). Plasma catecholamines (unchanged during euglycemia) rose during hypoglycemia with epinephrine, increasing approximately fivefold more than norepinephrine. In contrast, the hypoglycemia-induced increments in muscle dialysate norepinephrine and epinephrine were similar, suggesting local generation of norepinephrine. Compared with euglycemia, hypoglycemia produced a greater increase in lactate and a smaller reduction in alanine in muscle ECF, whereas hypoglycemia caused a greater relative fall in ECF glucose concentrations in muscle (72 +/- 16%) and adipose tissue (69 +/- 9%) than in plasma (42 +/- 3%) (P < 0.05). We conclude that hypoglycemia increases the generation of norepinephrine and gluconeogenic substrates in key target tissues, while increasing the plasma-tissue concentration gradient for glucose. These changes suggest the stimulation of glucose extraction by peripheral tissues, despite systemic counterregulatory hormone release and local sympathetic activation.

Adipose Tissue↗
PubMed1983

Influence of dietary lead and calcium on tissue lead accumulation and depletion, lead metabolism and tissue mineral composition in sheep.

Two experiments were conducted to study the metabolism and tissue accumulation and depletion of dietary Pb in sheep. In Exp. 1, a feeding trial, 33 wethers, 56 kg initially, were assigned randomly to two dietary treatments: .25% Ca plus 1,000 ppm Pb or .50% Ca plus 1,000 ppm Pb. Supplemental Ca and Pb were supplied as reagent grade calcium carbonate or reagent grade lead acetate. The experiment was divided into two phases of 75 and 180 d; during the first phase, diets contained 1,000 ppm supplemental Pb and during the second phase, diets contained 3 ppm Pb. Calcium level remained constant within treatments throughout both phases. Sheep were slaughtered at various intervals during both phases and tissue samples taken. Lead increased in all tissues during the accumulation period and decreased during the depletion period; however, kidney was the only tissue in which Pb concentration declined to control values by 180 d. Dietary Ca reduced (P less than .05) the concentration of Pb deposited in liver, but not in other tissues. Interactions of dietary Ca and Pb on tissue concentration of various minerals occurred. In Exp. 2, a balance trial, 27 wethers, 53 kg initially, were allotted randomly to four treatments in a 2 X 2 factorial arrangement. Diets contained either 0 or 1,000 ppm supplemental Pb as reagent grade lead acetate and .25 or .50% total Ca with supplemental Ca from calcium carbonate. Increasing dietary Pb increased (P less than .05) percentage of Pb retained and increased (P less than .01) whole blood Pb concentration (1.0 vs 1.42 micrograms/ml).

Animals↗
PubMed1994

Formation of healing tissue and angiogenesis in repair of connective tissue stimulated by epidermal growth factor.

Epidermal growth factor (EGF) has been shown to stimulate connective tissue repair in the perforated mesentery of rats. The aim of the present investigation was to study the effect of EGF on the formation of healing tissue and angiogenesis in such repair. After laparotomy standardised perforations were made in the centre of the mesenteric "windows" with a scalpel. The rats were given intraperitoneal injections of either 10 micrograms EGF dissolved in phosphate-buffered saline (PBS), or PBS alone, twice daily for four consecutive days beginning on the day of operation. In the first experiment, healing tissue formation and angiogenesis was quantified morphometrically in perpendicularly cut mesenteric windows on days 1 to 10 after operation. Treatment with EGF caused the formation of significantly more healing tissue on days 2 to 7, but no stimulation of angiogenesis. In the second experiment, angiogenesis was quantified morphometrically on days 14 and 21. Mesenteric windows were spread out on objective slides after the capillary bed had been visualised by perfusion of carbon ink. Perforation caused a significant increase of microvascular density in the centre of the mesenteric windows on days 14 and 21. Treatment with EGF did not stimulate angiogenesis at any observation point. In conclusion, treatment with EGF significantly increased the formation of healing tissue in connective tissue repair in the perforated mesentery of rats, but did not affect angiogenesis.

Animals↗
PubMed2000

Racemization and isomerization of type I collagen C-telopeptides in human bone and soft tissues: assessment of tissue turnover.

Urinary excretion of the type I collagen C-telopeptide (CTx) has been shown to be a sensitive index of the rate of bone resorption. The human type I collagen sequence A(1209)HDGGR(1214) of CTx can undergo racemization of the aspartic acid residue Asp(1211) and isomerization of the bond between this residue and Gly(1212). These spontaneous non-enzymic chemical reactions takes place in vivo in bone, and the degree of racemization and isomerization of CTx molecules may be an index of the biological age and the remodelling of bone. The aim of the present study was to investigate the degree of racemization and isomerization of type I collagen in human connective soft tissues, in order to estimate the rate of collagen turnover in adult tissues and compare it with that of bone. We also performed a systematic evaluation of the pyridinium cross-link content in adult human tissues. Using antibodies raised against the different CTx forms, we found that bone and dermis are the tissues that show most racemization and isomerization. The type I collagen of arteries, lung, intestine, kidney, skeletal muscle and heart shows significantly less racemization and isomerization than that of bone, suggesting that these soft tissues have a faster turnover than bone. We also found that pyridinoline and, to a lesser degree, deoxypyridinoline are distributed throughout the different tissues investigated. Because bone type I collagen is characterized by a high degree of both racemization/isomerization and deoxypyridinoline cross-linking, the concomitant assessment of these two post-translational modifications is likely to result in a highly specific marker of bone resorption.

Aged↗
PubMed2003

Hepatocyte growth factor receptor, matrix metalloproteinase-11, tissue inhibitor of metalloproteinase-1, and fibronectin are up-regulated in papillary thyroid carcinoma: a cDNA and tissue microarray study.

PURPOSE: To screen and validate the global gene expression in papillary thyroid carcinoma (PTC) using cDNA expression arrays and immunohistochemistry on tumor tissue microarrays in an attempt to find genes that may be of importance in the molecular pathogenesis and malignant progression of PTC. EXPERIMENTAL DESIGN: Eighteen PTC tissue specimens were compared with three morphologically normal thyroid specimens by applying Atlas Human Cancer 1.2 Array membranes printed with cDNAs of 1176 human genes involved in cancer. Results for selected genes were confirmed by reverse transcription-PCR. Protein expression of selected genes was further studied using a tissue microarray consisting of 107 PTCs and compared with histologically normal thyroid tissue samples. RESULTS: By cDNA arrays, two genes [c-MET and matrix metalloproteinase (MMP)-11] were expressed only in tumor tissue, where they were present in >50% of cases. Ten genes [macrophage inhibitory cytokine-1, CGD, fibronectin (FN), hypoxia-inducible factor 1, Fc-epsilon-receptor gamma-chain, lactate dehydrogenase A, HLA-DBP1, AH receptor, tissue inhibitor of metalloproteinase (TIMP-1), and glycyl-tRNA-synthetase] were found to be up-regulated >2-fold in 40-100% of cancers, whereas 9 genes (GADD153, polykystic kidney disease-1, CYR61, DPC4, HBA1, gravin, DLG3, protein tyrosine phosphatase sigma, and heterochromatin protein 1 homologue-alpha) were down-regulated to <50% of their normal levels in 40-94% of cases. Conventional reverse transcription-PCR gave consistent results with the cDNA array findings for all four genes selected to be studied (c-MET, FN, TIMP-1, and GADD153). Immunohistochemistry for three selected proteins, FN, MMP-11, and TIMP-1, showed positive staining in 81, 87, and 68% of the tumor samples, respectively. CONCLUSIONS: Several novel and previously undetected tumor promoting/inhibiting genes may be of importance in the molecular pathogenesis and malignant progression of PTC. Transcription of these genes may result in overexpression of proteins, such as c-MET, MMP-11, TIMP-1, and FN, which may contribute to the pathogenesis of PTC.

Carcinoma, Papillary↗
PubMed2003

Degeneration of bioprosthetic heart valve cusp and wall tissues is initiated during tissue preparation: an ultrastructural study.

BACKGROUND AND AIM OF THE STUDY: Chronic tissue degeneration is a major factor in the failure of porcine bioprosthetic heart valves. Stabilization with glutaraldehyde (GA) has become the standard in preparation of bioprosthetic heart valves, but there is increasing evidence that GA does not effectively stabilize all tissue structures, specifically glycosaminoglycans (GAGs). The study aim was to establish the status of GAGs in bioprosthetic heart valves and to ascertain whether degeneration of the extracellular matrix (ECM) is initiated during preparation of porcine tissues for use as bioprosthetic heart valves. METHODS: Stentless porcine bioprosthetic heart valves were prepared by tissue harvesting, 24 h of storage in cold saline, and 14 days' fixation in buffered 0.6% GA. Tissue samples obtained from fresh and fixed aortic cusps and wall conduit were analyzed for ECM integrity and GAG localization by transmission electron microscopy combined with toluidine blue staining. RESULTS: Major degenerative changes occurred in the ECM ultrastructure of both porcine cusp and wall during tissue preparation for use as bioprosthetic heart valves. Modifications in the aortic cusp included loss of GAGs from the interfibrillary space and from the surface of the collagen fibers. In the aortic wall, GAGs were lost from the interfibrillary space and from the surface of collagen fibers. In addition, the surface of wall elastic fibers exhibited marked paucity of GAGs and elastin-associated microfibrils. CONCLUSION: The typical steps involved in the preparation of porcine aortic bioprosthetic heart valves induce, or cannot fully prevent, degeneration of some components of the ECM. Controlling the extent of this pre-implantation deterioration will open new gateways for improvement of the quality and durability of future cardiovascular bioprostheses.

Animals↗
PubMed1992

Tissue distribution of human minor histocompatibility antigens. Ubiquitous versus restricted tissue distribution indicates heterogeneity among human cytotoxic T lymphocyte-defined non-MHC antigens.

We determined the tissue distribution of 7 human minor histocompatibility (H) Ag. Each of these Ag is defined by one or more MHC class I-restricted CTL clones, previously generated from PBL primed against minor H Ag by HLA-identical bone marrow transplantation (BMT). CTL-mediated lysis of tissue-derived cells and cultured cell lines was used as an in vitro assay for minor H Ag expression of several human tissues. The Ag HA-3 (HLA-A1-restricted), HA-4 (HLA-A2 restricted), HA-6 and HA-7 (HLA-B7 restricted), and the male-specific Ag H-Y (HLA-A2 and B7 restricted) were found to be expressed on cells of all tissues tested. In contrast, the HLA-A2-restricted Ag HA-1 and HA-2 were demonstrated on PHA-blasts, EBV-BLCL, purified T cells, B cells, monocytes, and immature thymocytes, but could not be demonstrated on skin-derived cultured fibroblasts, keratinocytes, melanocytes, cultured epithelial cells of kidney proximal tubili, and umbilical cord vein-derived endothelial cells. Incubation of the latter cell lines with rIFN-gamma, rTNF-alpha, and/or rIL-1 alpha, in concentrations shown to maximally increase their susceptibility to lysis by allo-MHC class I CTL, did not induce recognition by HA-1- and HA-2-specific CTL in vitro. These results indicate an ubiquitous tissue expression of the minor H Ag HA-3, -4, -6, -7 and H-Y in contrast to a to the hemopoietic cell lineage-restricted expression for HA-1 and HA-2. The heterogeneity in tissue expression of T cell-defined, class I-restricted non-MHC Ag implies that they might be derived from intracellular proteins with either an ubiquitous or a more specialized cell type-specific function.

Cytotoxicity, Immunologic↗
PubMed2004

Postextraction tissue management: a soft tissue punch technique.

The aim of this prospective clinical study was to analyze graft-enhanced soft tissue healing during the initial phases after tooth extraction. Twenty patients in need of tooth extraction (incisors, canines, and premolars) and implant replacement were included. In patients with multiple extractions, one tooth was randomly selected for treatment. After administration of antibiotics, the selected tooth was gently removed. The socket was completely filled with deproteinized bovine bone mineral integrated in a 10% collagen matrix to fill out the space of the alveolus and support the soft tissue. A biopsy punch with a diameter corresponding to the socket orifice was chosen to harvest a free gingival graft of 2- to 3-mm thickness from the palate. The punched graft was carefully sutured to the deepithelialized soft tissue margins of the socket. One week after graft insertion, 64.3% of the mean graft area was fully integrated, 35.6% was fibrinoid, and 0.1% showed necrotic parts. Three and 6 weeks postsurgery, the mean integrated graft surface increased to 92.3% and 99.7%, respectively. After 6 weeks, a mean of 0.3% of the surface in four grafts showed incomplete wound closure, and no fibrin or necrosis was present. Colorimetry of the graft and adjacent tissue revealed a mean color match of deltaE = 2.91, lower than the critical threshold of 3.7 for intraoral visibility of different colors. This soft tissue punch technique led to successful biologic and esthetic integration of the transplanted graft into the local host tissues.

Adult↗
PubMed2005

[Experimental study on constructing muscle tissue in rabbits with tissue engineering methods].

OBJECTIVE: To explore the possibility of constructing tissue engineering muscles by combining allogeneic myoblasts with small intestinal submucosa (SIS) in rabbits. METHODS: A large number of purified myoblasts were obtained with multi-procedure digestion and repeated attachment method from skeletal muscles taken from extremities of immature rabbits which were born 7 days ago. The myoblasts were labeled with BrdU, and then combined with SIS to construct tissue engineering muscles. This kind of tissue engineering muscles were grafted into the gastrocnemius muscle defect (1.5 cm in length, 1.0 cm in width) of fifteen rabbits as the experimental group. The SIS was grafted into the same position in the control group. The rabbits were sacrificed 4, 6, 8 weeks after operation. The tissue engineering muscles were evaluated by macroscopic, histological and immunohistochemical observations, and by quantitative analysis of local immunocyte in the grafting site. RESULTS: Allogeneic myoblasts with SIS were combined perfectly in vitro. The SIS was connected tightly to surrounding skeletal muscles and inflammation response was obvious 4 weeks after grafting. The SIS began to break down and inflammation response became slight 6 and 8 weeks after operation. Compared with that of 8th week, the quantitative analysis of local immunocyte in 4th and 6th week in both experimental and control group has significance (P<0.05). Newly formed muscle tissues were found around SIS in the experimental group in 4th, 6th, and 8th week. Expression of BrdU and myosin immunohistochemical staining were positive in the experimental group and negative in the control group. CONCLUSION: Tissue engineering muscles of rabbits which are constructed by combining allogeneic myoblasts with SIS can survive and proliferate.

Animals↗
PubMedDate not supplied

Potential error in the measurement of tissue to blood distribution coefficients in physiological pharmacokinetic modeling. Residual tissue blood. I. Theoretical considerations.

Physiological pharmacokinetic models require the determination of tissue to blood distribution coefficients. A theoretical model has been developed and the resulting equations indicate that under certain conditions it is necessary to correct for the presence of drug in the residual blood remaining in the tissue. The potential error in ignoring this residual blood is expressed mathematically in terms of several important factors that include the anatomical features of the tissue (volume fractions of the blood, interstitial fluid, and cellular space) as well as the physicochemical properties of the drug (extent of binding in the blood and tissues). These theoretical considerations and resulting simulations have been applied to experimental literature data for several compounds (methotrexate, digoxin, and biperiden). We conclude that correction for the residual blood is necessary when the values of tissue to blood distribution coefficients are very small or large (relative to one) and when the volume fraction of the blood in tissue is substantial.

Animals↗
PubMed1989

Selective cellular expression of tissue factor in human tissues. Implications for disorders of hemostasis and thrombosis.

Tissue factor (TF), the primary cellular initiator of the coagulation protease cascade, is implicated in having important roles in hemostasis, thrombogenesis, inflammation, and the cellular immune response, although the cytologic distribution of TF in tissues has yet to be described. This study used epitope-defined monoclonal antibodies to human tissue factor for immunohistochemical localization of TF in normal human tissues. TF was selectively expressed in tissues and was associated with cells rather than extracellular matrix. It was anatomically sequestered from blood, being undetectable in endothelium and peripheral blood cells. TF was present in vascular adventitia, organ capsules, epidermis, and mucosal epithelium. Most dermal and submucosal fibroblasts were negative. Except for alveolar macrophages and possibly dendritic cells of some lymphoid follicles, tissue macrophages did not express TF; (expression was demonstrable in LPS stimulated monocytes). Cerebral cortex, renal glomeruli, and cardiac myocytes were additional sites of prominent TF expression. Based on the cellular distribution of TF, it is hypothesized that intravascular initiation of coagulation requires induced expression by intravascular cells, and that the normal distribution of TF represents a hemostatic "envelope" ready to activate coagulation when vascular integrity is disrupted.

Blood Cells↗
PubMed1989

Tissue expanders in soft tissue reconstruction.

In order to reconstruct soft tissue defects, plastic and reconstructive surgeons have developed various means that range from the simplest skin grafts to the most complex transfer of microvascular free flaps, but there are no other more than tissue expansion can achieve good results in both aesthetic and functional aspects. From Oct. 1986 to Oct. 1988, tissue expansion was used in seven male and six female patients aged from 11 to 40 years, with a mean of 25. They were divided into 3 groups according to the location of defects: head and neck, 6 cases; trunk, 2 cases; and extremity, 5 cases. Seven cases had successful results and 6 cases failed: one due to infection, one due to leakage of bag and another 4 due to expander extrusion. We know that tissue expansion is a relatively new technique. It expands the healthy tissue immediately adjacent to the defects and provides tissue with near perfect color match, texture, sensation and hair distribution for reconstruction. Although high risk of failure was noted (6 in 13 cases), it still deserves trying for its reasonable aesthetic and functional results.

Adolescent↗
PubMed1980

Metabolic studies of N-bases of phospholipids and long chain bases of sphingolipids in two-weeks-old mouse brain tissue in comparison with one-month-old mouse visceral tissues.

After intraperitoneal administration of 15N-labeled serine, ethanolamine and choline to young mice showing active myelination, the incorporation of 15N-atom into N-bases of phospholipids and long chain bases of sphingolipids in brain tissue was particularly investigated in comparison with those in visceral tissues of adult mouse. After intraperitoneal injection of DL-[15N]-serine into mice, it was found that the 15N-atom was obviously incorporated into phosphatidylserine, phosphatidylethanolamine, ethanolamine-plasmalogen and long chain bases of cerebroside, sphingomyelin and gangliosides, but not significantly into phosphatidylcholine. The apparent maximum rates of the incorporation were also calculated. After administration of [15N]-ethanolamine, the 15N-atom was predominantly incorporated into phosphatidylethanolamine and next into ethanolamine-plasmalogen, but also not significantly into phosphatidylcholine. After administration of [15N]-choline chloride, the 15N-atom was incorporated into phosphatidylcholine and sphingomyelin, but not into other phospholipids and sphingolipids. These results suggested that serine, ethanolamine and choline are available for the biosynthesis of the N-bases of phospholipids in the brain tissue of young mouse and that serine is also utilized for the biosynthesis of long chain bases of sphingolipids. However, neither biosynthesis of choline from ethanolamine nor of phosphatidylcholine from phosphatidylethanolamine by methylation seemed to take place even in the brain tissue of young mouse, while the decarboxylation of phosphatidylserine into phosphatidylethanolamine was obviously observed. The decarboxylation rate of phosphatidylserine into phosphatidylethanolamine in the brain tissue of young mouse seemed to be approximately at the same level with the other tissues like liver, lung spleen and kidney of adult mouse.

Aging↗
PubMed1993

Tissue-specific and hormonally controlled alternative promoters regulate aromatase cytochrome P450 gene expression in human adipose tissue.

Estrogen biosynthesis is catalyzed by a microsomal enzyme, aromatase cytochrome P450 (P450arom; the product of the CYP19 gene). The human CYP19 gene comprises nine coding exons, II-X. Additionally, tissue-specific expression is determined by the use of tissue-specific promoters, which give rise to P450arom transcripts with unique 5'-noncoding sequences. In placenta, P450arom transcripts contain one of two 5'-untranslated exons, I.1 or I.2, while ovarian transcripts instead contain sequence consistent with the use of a promoter, PII, which is proximal to the start of translation. To characterize transcripts present in adipose tissue and adipose stromal cells (ASC) in culture, cDNA libraries were constructed by the RACE (rapid amplification of cDNA ends) procedure. Four P450arom transcripts with unique 5' termini were identified, leading to the characterization of two unique 5'-untranslated exons of the CYP19 gene, I.3 and I.4. Whereas I.3-specific sequence is expressed in adipose tissue as well as in ACS maintained under all culture conditions, I.4-specific sequence is apparently present only in breast adipose tissue, and ACS stimulated with glucocorticoids. On the other hand, PII-specific sequence is present only in cells stimulated with cAMP analogues and is absent from cells stimulated with glucocorticoids. We conclude that CYP19 gene expression in human adipose tissue likely utilizes two novel promoters and, furthermore, that alternative promoter usage in cultured ASC is a function of the hormonal environment in which the cells are maintained.

Adipose Tissue↗
PubMed1993

Improved tissue corrosion of vascular casts: a quantitative filtration method used to compare tissue corrosion in various concentrations of sodium and potassium hydroxide.

In this study, we compare weights of filter retained material (11 microns particle retention) after solubilization and filtration of unfixed, un-perfused tissue (fat, liver and trachea) in sodium and potassium hydroxide (1%, 5%, 10% and 20% weight/volume, w/v) at 8, 24 and 48 hour time points at 45 degrees C. Three detergents [1% Triton-X-100 (volume/volume, v/v), 1% 7X (v/v), 1% Terg-A-Zyme (w/v)] used in combination with hydroxide were evaluated for use in solubilizing fat. Additionally, vascular casts from mouse kidneys were corroded to test the practical effectiveness of corroding solutions on resin infused tissue. Five percent KOH for eight hours proved to be the most effective concentration and time required to corrode fatty tissue. Liver tissue was corroded most rapidly in 1% to 5% NaOH or in 1% to 20% KOH. Corrosion of trachea tissue showed that 5, 10 and 20% hydroxide (NaOH or KOH) are equally effective after 8 hours of corrosion. Use of detergents improved solubilization of fat when combined with 2%, 3% or 5% NaOH. However, fatty tissue was solubilized more rapidly without the use of detergents in 1% NaOH. Scanning electron microscopy of vascular casts shows that corrosion in 1% NaOH appears equally as effective as corrosion in 15% KOH.

Adipose Tissue↗
PubMed1994

Perinatal hypothyroidism impairs the normal transition of GLUT4 and GLUT1 glucose transporters from fetal to neonatal levels in heart and brown adipose tissue. Evidence for tissue-specific regulation of GLUT4 expression by thyroid hormone.

GLUT1 and GLUT4 glucose transporter expression is highly regulated in muscle and adipose tissue during perinatal life. Here we have investigated the role of thyroid hormones in the regulation of GLUT4 induction and GLUT1 repression associated to neonatal development. Perinatal hypothyroidism markedly impaired GLUT4 protein induction in heart. This effect was heart specific, and a greater expression of GLUT4 was detected in brown adipose tissue from neonatal hypothyroid rats compared with controls. These changes in GLUT4 protein expression were not detected in brown adipose tissue or heart when hypothyroidism was induced in adult rats. These results indicate that GLUT4 induction during perinatal life is highly sensitive to thyroid hormones in both heart and adipose tissue. Perinatal hypothyroidism was characterized by decreased cardiac GLUT4 mRNA concentrations. T3 injection caused a marked increase in cardiac levels of GLUT4 mRNA in hypothyroid neonates. Thus, in 13-day-old hypothyroid rats, GLUT4 mRNA levels increased 3-fold 1 h after T3 injection. Under these conditions, retinoic acid also caused a rapid increase in cardiac GLUT4 mRNA levels from hypothyroid neonates. In addition, cardiac levels of GLUT4 protein markedly increased in fetuses and in neonates 24 h after T3 injection. These findings suggest that a direct effect of thyroid hormones is the promotion of cardiac GLUT4 gene expression. GLUT1 protein expression was markedly enhanced in brown adipose tissue and heart during neonatal hypothyroidism as well as in hypothyroidism induced in adult rats. This was concomitant to greater levels of GLUT1 mRNA in hearts from hypothyroid neonates. Immunofluorescence analysis indicated that cardiomyocytes from hypothyroid pups contained an enhanced level of GLUT1 protein. Furthermore, T3 injection caused a decrease in cardiac levels of GLUT1 mRNA in hypothyroid neonates. These results indicate that thyroid hormone manipulation leads to inverse regulation of GLUT1 and GLUT4 glucose transporter gene expression in the neonatal heart. We conclude that thyroid hormones play a pivotal role controlling the transition of glucose transporter carriers from fetal to neonatal levels in heart and brown adipose tissue.

Adipose Tissue, Brown↗