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At least 1,297 records · Page 72Linked to original sources
PubMed1998

Chemokine receptors in human endothelial cells. Functional expression of CXCR4 and its transcriptional regulation by inflammatory cytokines.

Chemokines play an important role in the regulation of endothelial cell (EC) function, including proliferation, migration and differentiation during angiogenesis, and re-endothelialization after injury. In this study, reverse transcriptase-polymerase chain reaction was used to reveal expression of various CXC and CC chemokine receptors in human umbilical vein EC. Northern analysis showed that CXCR4 was selectively expressed in vascular EC, but not in smooth muscle cells. Compared with other chemokines, stromal cell-derived factor-1alpha (SDF-1alpha), the known CXCR4 ligand, was an efficacious chemoattractant for EC, causing the migration of approximately 40% input cells with an EC50 of 10-20 nM. Of the chemokines tested, only SDF-1alpha induced a rapid, though variable mobilization of intracellular Ca2+ in EC. Experiments with actinomycin D demonstrated that CXCR4 transcripts were short-lived, indicating a rapid mRNA turnover. Interferon-gamma (IFN-gamma) caused a pronounced down-regulation of CXCR4 mRNA in a concentration- and time-dependent manner. In a striking functional correlation, IFN-gamma treatment also attenuated the chemotactic response of EC to SDF-1alpha. IL-1beta, tumor necrosis factor-alpha, and lipopolysaccharide produced a time course-dependent biphasic effect on CXCR4 transcription. Expression of CXCR4 in EC is significant, more so as it and several CC chemokine receptors have been shown to serve as fusion co-receptors along with CD4 during human immunodeficiency virus infection. Taken together, these findings provide evidence of chemokine receptor expression in EC and offer an explanation for the action of chemokines like SDF-1alpha on the vascular endothelium.

Calcium↗
PubMed1991

Developmental expression of HNK-1-reactive antigens in rat cerebral cortex and molecular heterogeneity of sulfoglucuronylneolactotetraosylceramide in CNS versus PNS.

Monoclonal antibody HNK-1 reacts with a carbohydrate epitope present in proteins, proteoglycans, and sulfoglucuronylglycolipids (SGGLs). On high-performance TLC plates, SGGLs of the CNS from several species migrated consistently slower than those from the PNS, a result indicating possible differences in the structures. The structural characteristics of the major SGGL, sulfoglucuronylneolactotetraosylceramide (SGGL-1), from CNS was compared with those of SGGL-1 from PNS. Although the composition, sequence, and linkages of the carbohydrate moiety of the SGGL-1 species were identical, SGGL-1 from CNS contained mainly short-chain fatty acids, 16:0, 18:0, and 18:1, amounting to 85% of the total fatty acids, whereas SGGL-1 from PNS contained large proportions (59%) of long-chain fatty acids (greater than 18:0). These differences in the fatty acid composition accounted for the different migration pattern observed. The developmental expression of SGGLs and HNK-1-reactive proteins was studied in rat cerebral cortex between embryonic day (ED) 15 to adulthood. SGGLs in the rat cortex were maximally expressed around ED 19 and almost completely disappeared by postnatal day (PD) 20. This expression was contrary to their increasing expression in the cerebellum and sciatic nerve with postnatal development. Six to eight protein bands with a molecular mass of greater than 160 kDa were HNK-1 reactive in the rat cerebral cortex at different ages. The major HNK-1 reactivity to the 160-kDa protein band seen in ED 19 to PD 10 cortex decreased and completely disappeared from the adult cortex, whereas several other proteins remained HNK-1 reactive even in the adult. Western blot analyses of the neural cell adhesion molecules (N-CAMs) during development of the rat cortex with a polyclonal anti-N-CAM antibody showed that the major HNK-1-reactive protein bands were not N-CAMs. Between PD 1 and 10, 190-200-kDa N-CAM was the major N-CAM, and between PD 15 to adulthood, 180-kDa N-CAM was the only N-CAM present in the rat cortex.

Amino Acid Sequence↗
PubMed2003

Preferential locomotion of leukemic cells towards laminin isoforms 8 and 10.

To identify the laminin isoforms of the basement membranes that could be implicated in the extravasation process of neoplastic lymphocytes, a number of purified laminins and one native renal laminin complex were comparatively investigated for their ability to promote migration of neoplastic lymphocytes in vitro. The identity/composition of a human placental laminin complex was asserted by combining immunochemical assays, sequence determination of tryptic peptides, and ultrastructural analysis to be composed predominantly of laminin-10 in which the coiled-coil C-terminal regions and the G globular domain of the alpha5 chain were preserved intact despite the enzymatic treatment used for its isolation. Lymphoma and leukemic cell lines failed to migrate towards laminin-4, -9, -11, moved poorly in response to laminin-1, -2/4, -5 and the renal laminin complex, but markedly locomoted towards the subendothelial laminin-8 and -10. The motility-promoting interaction with these latter laminins was interchangeably mediated by the alpha3beta1 and alpha6beta1 integrins. Lymphocyte locomotion on laminins assayed in the presence of cytokines was either reduced or enhanced suggesting that local cytokine milieu could further influence motility response.

B-Lymphocytes↗
PubMed2006

Sugar antennae for guidance signals: syndecans and glypicans integrate directional cues for navigating neurons.

Attractive and repulsive signals guide migrating nerve cells in all directions when the nervous system starts to form. The neurons extend thin processes, axons, that connect over wide distances with other brain cells to form a complicated neuronal network. One of the most fascinating questions in neuroscience is how the correct wiring of billions of nerve cells in our brain is controlled. Several protein families are known to serve as guidance cues for navigating neurons and axons. Nevertheless, the combinatorial potential of these proteins seems to be insufficient to sculpt the entire neuronal network and the appropriate formation of connections. Recently, heparan sulfate proteoglycans (HSPGs), which are present on the cell surface of neurons and in the extracellular matrix through which neurons and axons migrate, have been found to play a role in regulating cell migration and axon guidance. Intriguingly, the large number of distinct modifications that can be put onto the sugar side chains of these PGs would in principle allow for an enormous diversity of HSPGs, which could help in regulating the vast number of guidance choices taken by individual neurons. In this review, we will focus on the role of the cell surface HSPGs syndecan and glypican and specific HS modifications in promoting neuronal migration, axon guidance, and synapse formation.

Animals↗
PubMed2000

Role of lysophosphatidic acid and rho in glioma cell motility.

We have studied the effects of the bioactive phospholipid lysophosphatidic acid (LPA) on cell lines derived from highly invasive human glioblastoma multiforme (GBM). Using transwell migration assays, we show that LPA stimulates both chemokinetic and chemotactic migration of glioma cells. Blood brain barrier breakdown and leakage of serum components that most likely include LPA are common features of GBM. Therefore, the effects of LPA on glioma cell motility are intriguing given the fact that, in vivo, GBM cells often migrate great distances from the main tumor, rendering successful therapy extremely difficult. We show here that LPA initiates a variety of signaling cascades in glioma cells. LPA-enhanced transwell migration was sensitive to pertussis toxin (PTX) treatment suggesting an important role for G(i) subtype of G proteins. LPA also stimulated Ca(2+) fluctuations and activation of extracellular signal-regulated kinases (ERKS) 1 and 2, although blocking either pathway had little effect on glioma cell migration. Exposure of glioma cells to LPA resulted in phosphorylation of the regulatory light chain (RLC) of myosin II and the formation of stress fibers and focal adhesions. These effects were blocked by Y-27632, an inhibitor of Rho-activated ROCK kinases. Time-lapse video microscopy revealed that Y-27632-treatment caused cells to assume long thin morphologies that suggested deficiencies in the contractile apparatus. Furthermore, many cells exhibited a conspicuous extension of processes when Rho/ROCK kinase cascades were inhibited. The above results suggest that LPA/Rho signaling cascades play important roles in glioma cell motility and that exposure of tumor cells to LPA in vivo may contribute to their invasive phenotype.

Cell Movement↗
PubMed2001

Separation of double-stranded DNA fragments by capillary electrophoresis in interpenetrating networks of polyacrylamide and polyvinylpyrrolidone.

Mixtures of two polymers with totally different chemical structures, polyacrylamide and polyvinylpyrrolidone (PVP) have been successfully used for double-stranded DNA separation. By polymerization of acrylamide in a matrix of PVP solution, the incompatibility of these two polymers was suppressed. Laser light scattering (LLS) studies showed that highly entangled interpenetrating networks were formed in the solution. Further systematic investigation showed that double-stranded DNA separation was very good in these interpenetrating networks. With a concentration combination of as low as 2% w/v PVP (weight-average molecular mass Mr = 1 x 10(6) g/mol) + 1% w/v polyacrylamide (Mr = 4 x 10(5) g/mol), the 22 fragments in pBR322/HaeIII DNA, including the doublet of 123/124 bp, have been successfully separated within 6.5 min. Under the same separation conditions, similar resolution could only be achieved by using polyacrylamide (Mr = 4 x 10(5) g/mol) with concentrations higher than 6% w/v and could not be achieved by using only PVP (Mr = 1 x 10(6) g/mol) with a concentration as high as 15% w/v. It is noted that the interpenetrating network formed by 2% PVP and 1% polyacrylamide has a very low viscosity and can dynamically coat the inner wall of a fused-silica capillary. The separation reached an efficiency of more than 10(7) theoretical plate numbers/m and a reproducibility of less than 1% relative standard deviation of migration time in a total of seven runs. The interpenetrating network could stabilize polymer chain entanglements. Consequently, the separation speed was increased while retaining resolution.

Acrylic Resins↗
PubMed1995

Molecular cloning of tyrosine kinases in the early Xenopus embryo: identification of Eck-related genes expressed in cranial neural crest cells of the second (hyoid) arch.

Growth factors and their receptors play an important role in controlling cellular proliferation, migration, and differentiation during vertebrate embryogenesis. We have used the reverse transcription-polymerase chain reaction to survey the repertoire of receptor tyrosine kinases (TK) expressed during early embryogenesis of Xenopus laevis. Twelve distinct Xenopus TK cDNA classes were identified among a total of 352 cDNAs screened. A single TK cDNA class has been described previously and encodes the fibroblast growth factor receptor FGFR-A1. The remaining 11 TK cDNA classes appear to encode novel genes of the FGFR, platelet-derived growth factor receptor (PDGFR), Eph, Csk, Tyk2, and Klg subfamilies. By RNase protection assays, Xenopus TK mRNAs are rare transcripts (< 10(7) mRNA molecules/embryo), and are usually found to be expressed also maternally in the embryo. Most Xenopus TK genes examined by whole-mount in situ hybridization were expressed widely in tissues derived from multiple germ layers. Two Eck-related genes, however, were found to be restricted in their expression to neural crest of the second (hyoid) arch. Our findings are consistent with the proposed function of TKs in the regulation of specification and differentiation of embryonic tissues.

Amino Acid Sequence↗
PubMed2002

Migration of CX3CR1-positive T cells producing type 1 cytokines and cytotoxic molecules into the synovium of patients with rheumatoid arthritis.

OBJECTIVE: Rheumatoid arthritis (RA) is characterized by chronic inflammation of multiple joints. Large numbers of T cells, which produce type 1 cytokines, infiltrate into RA synovium. Chemokines and chemokine receptors are considered to contribute to the T cell infiltration. In this study, we examined the role of CX3CL1/fractalkine and its receptor CX3C chemokine receptor 1 (CX3CR1) in the T cell migration into RA synovium. METHODS: Using flow cytometry, immunohistochemistry, and reverse transcription-polymerase chain reaction, we analyzed CX3CR1 expression by peripheral blood and synovial T cells, and CX3CL1 expression in synovium from patients with RA. Cytokine and cytotoxic molecule expression by CX3CR1-positive T cells was analyzed by flow cytometry. RESULTS: CX3CR1 expression by peripheral CD4+ and CD8+ T cells was up-regulated in RA patients. The peripheral CD4+ and CD8+ T cells expressing CX3CR1 predominantly produced interferon-gamma and tumor necrosis factor alpha, and expressed cytotoxic molecules such as granzyme A and perforin. Furthermore, CX3CR1+,CD3+ T cells infiltrated into RA synovium. CX3CL1, the unique ligand of CX3CR1, was expressed by endothelial cells and synoviocytes in RA synovium, but not in osteoarthritis synovium. CONCLUSION: Our findings suggest that the interactions of CX3CL1 and CX3CR1 might contribute to the accumulation of CX3CR1+ T cells expressing type 1 cytokines and possessing cytotoxic granules in RA synovium.

Arthritis, Rheumatoid↗
PubMed2002

Effects of local interactions and local migration on stability.

Mathematical models can help to resolve the longstanding question of whether more diverse communities are more stable. Here, I focus on how local dispersal and local interactions--hallmarks of spatial communities--affect stability in a spatially implicit model with demographic stochasticity. The results are based on a novel way to analyze moment equations. The main conclusion is that the type and strength of density-dependent factors, such as fecundity and competition, determine whether local dispersal and local interactions increase or decrease stability. Local dispersal has a stabilizing effect when fecundity is high, interspecific competition is either low or high, and the number of species is small. Effects of local migration on stability are amplified when space is explicit.

Animal Migration↗
PubMed1995

Isomyosin patterns of single type IIB, IID and IIA fibres from rabbit skeletal muscle.

The present study demonstrates for the first time isomyosin patterns of the three fast-twitch fibre types IIB, IID/X, and IIA. Single muscle fibres were dissected from freeze-dried fibre bundles of rabbit adductor magnus, extensor digitorum longus, and psoas muscles. Pure fibre types, expressing only one myosin heavy chain isoform (MHCIIb, MHCIId/x, MHCIIa), were delineated by electrophoresis of fibre fragments under denaturing conditions. Pieces of the same fibres were then subjected to electrophoresis under non-denaturing conditions. A three-band pattern of fast isomyosins, representing the LC3f homodimer (FM1), the LC1f/LC3f heterodimer (FM2), and the LC1f homodimer (FM3), was detected in each of the three pure fibre types. Therefore, three isomyosins, different in their light chain complement, coexist in each pure fibre. The relative mobilities of the three bands, migrating in the order FM1 > FM2 > FM3, were the same in the three fibre types. The absolute electrophoretic mobilities of the MHCIIb-, MHCIId- and MHCIIa-based isomyosin triplets differed in the order MHCIIb triplets > MHCIId triplets > MHCIIa triplets. The proportions of FM1, FM2, and FM3 varied in type IIB, IID, and IIA fibres. FM2 was the dominant isomyosin in all three fibre types, but fibre type-related differences existed in the FM1 to FM3 ratio. This ratio was lowest in IIA fibres and highest in IIB fibres which agrees with our previous observations that the LC3f/(LC1f + LC3f) fraction is lowest in type IIA and highest in type IIB fibres.

Animals↗
PubMed1991

Fatal hyperammonemia resulting from a C-to-T mutation at a MspI site of the ornithine transcarbamylase gene.

Ornithine transcarbamylase (OTC) deficiency is the most common inborn error of the urea cycle in humans and is responsible for lethal neonatal hyperammonemia in males. Partial OTC deficiency also occurs in females and can be responsible for life-threatening hyperammonemic comas in heterozygotes. The cosegregation of the trait with a 5.8-kb abnormal MspI fragment in an affected family led us to hypothesize that this unexpected migration pattern was related to the mutation event in this particular family. Using polymerase chain reaction amplification of the specific mRNA derived from a post-mortem biopsy of the liver, we found that the MspI site located in the seventh exon of the gene was abolished and we finally identified a C-to-T transition at codon 225 of the cDNA, changing a proline to a leucine in the protein. Subsequent digestion of amplified exon 7 using the restriction enzyme MspI allowed direct screening for the mutant genotype during the next pregnancy. The present study supports the view that direct detection of the mutant genotype using either Southern blotting or digestion of amplified exons of the gene can contribute to genetic counselling in noninformative families. Finally, since MspI digestions are routinely performed for restriction fragment length polymorphism-based family studies in OTC deficiency, we suggest that the possible presence of the 5.8-kb abnormal fragment should be investigated on Southern blots of affected individuals.

Amino Acid Metabolism, Inborn Errors↗
PubMed2001

An original approach in the diagnosis of early breast cancer: use of the same radiopharmaceutical for both non-palpable lesions and sentinel node localisation.

A modern approach to the surgical treatment of early breast carcinoma requires intraoperative localisation of non-palpable lesions and assessment of the lymph node status. Localisation of breast lesions can be achieved by intratumoural injection of a small amount of radiotracer and intraoperative use of a gamma probe (i.e. radioguided occult lesion localisation, or ROLL). Assessment of the lymph node status is possible by means of the sentinel node approach. To date, two different radiopharmaceuticals have been used for localisation of tumour and sentinel node. We now propose the use of a single nanocolloidal tracer (Nanocoll, with a particle size of less than 80 nm) which is labelled with technetium-99m for simultaneous performance of ROLL and sentinel node identification. The aim of this study was to evaluate the feasibility of this approach, which should be easier and more practical than the dual-tracer injection method. We have employed this new technique in 73 patients with non-palpable, cytologically diagnosed breast cancer and non-palpable axillary lymph nodes. In all patients the radiocolloid, in a total volume of 0.3-0.4 cc, was injected under sonographic or stereotactic guidance. Half of the dose was injected intratumourally and half superficially, but very close to the tumour. Because of the slow lymphatic flow in the breast, Nanocoll must be injected some time before surgery in order to enable adequate migration to the axilla. We injected colloid in the afternoon before surgery (16-23 h before the start of the operation, with an average interval of 18 h). An average dose of 130 MBq (range 110-150) was injected in order to have about 10 MBq of radioactivity when surgery commenced. Lymphoscintigraphy was performed after 15-19 h, with an average interval of 17 h. The procedure was always successful in permitting the localisation of occult breast lesions. Lesions were always localised at the first attempt, and were always contained within the surgical margins. Histological examination revealed all 73 resected lesions to be malignant: there were 64 cases of infiltrating carcinoma and nine of intraductal carcinoma. All breast lesions were therefore confirmed to be early breast cancer. We achieved sentinel node localisation in 71 out of 73, either at scintigraphy or with the intraoperative probe; in two patients, radiopharmaceutical migration was absent. Lymphoscintigraphy showed only axillary drainage in 52 cases, only internal mammary chain (IMC) drainage in nine cases, and combined axillary and IMC drainage in eight cases. In two cases, lymphoscintigraphy suggested the sentinel node was located inside the same breast (intramammary lymph node). All the visualised sentinel nodes were biopsied except for four that were localised in the IMC. Histological examination of the nodes showed metastases in 20 cases: in 15 cases there were micrometastases, and in five, macrometastases. In conclusion, this study has demonstrated the feasibility of the proposed procedure. Simultaneous performance of ROLL and sentinel node localisation using a single tracer represents a useful and practicable choice in the management of early breast cancer.

Aged↗
PubMed1998

A common point mutation in the tyrosine hydroxylase gene in autosomal recessive L-DOPA-responsive dystonia in the Dutch population.

This report concerns one new mutation in the tyrosine hydroxylase (TH) gene in three patients originating from three unrelated Dutch families with autosomal recessive L-DOPA-responsive dystonia (DRD). In this study, all exons of the TH gene were amplified by the polymerase chain reaction and subjected to analyses by single-strand conformation polymorphism. An aberrant migration pattern was observed for exon 6 of the TH gene in all patients. Direct sequencing of the coding region of exon 6 revealed the presence of one novel missense mutation. An a698g transition resulted in the substitution of the evolutionary conserved arginine 233 by a histidine (R233H). All patients were homozygous for the mutation. This new mutation in the TH gene was confirmed by restriction enzyme analysis with the restriction enzyme HhaI. Thus, a high proportion of defective TH alleles may be R233H in The Netherlands.

Chromosomes, Human, Pair 11↗
PubMed2003

Role of epidermal growth factor and epidermal growth factor receptor on hemidesmosome complex formation and integrin subunit beta4.

Epidermal growth factor (EGF) stimulates integrin beta4 expression and synthesis in corneal epithelium through ligand binding to the EGF receptor, receptor dimerization and activation of the intracellular domain. We hypothesized that inhibition of EGF receptor messenger RNA (mRNA) would block integrin beta4 expression, which is induced by EGF. We also tested the hypothesis that EGF would cause the degradation of hemidesmosomes in control and injured corneal organ cultures. Primary rabbit corneal epithelial cell cultures or corneas were cultured in keratinocyte medium in the presence or absence of an antisense 20-mer phosphorothioate oligonucleotide complementary to the initiation codon region of EGF receptor mRNA. Cells were also cultured in the presence or absence of EGF. Sense and scrambled oligonucleotides similarly modified were used as controls. The concentration of EGF receptor mRNA was semiquantitatively determined by reverse transcriptase/polymerase chain reaction (RT-PCR). We found that transfection did inhibit EGFR expression and migration of epithelial cells and also demonstrated that EGFR mediated expression of integrin beta4 mRNA. Injury induced a decrease in hemidesmosomes that was enhanced with EGF but was not caused by the presence of growth factor in unwounded tissue. These results indicate that injury causes the activation of EGFR but that EGF alone is not responsible for the degradation of hemidesmosomes and that other growth factors play a role in the complex repair of wounds in an avascular tissue.

Animals↗
PubMed2004

Activation of hepatocyte growth factor in monkey stomach following gastric mucosal injury.

BACKGROUND: Hepatocyte growth factor (HGF) is involved in the proliferation and migration of various types of epithelial cells. HGF is produced as a single-chain precursor (pro-HGF) and functions after activation by HGF activator (HGFA). In this study, we aimed to examine the activation of pro-HGF to mature HGF and the expressions of HGF-related molecules, such as HGFA and HGFA inhibitor type 1 (HAI-1), in a monkey model of gastric mucosal injury. METHODS: Gastric mucosal injury was induced in Japanese monkeys by administration of HCl using nasal-gastric tubes. HGF activation was evaluated by Western blotting and enzyme-linked immunosorbent assay (ELISA), and the expression of HGF, HGFA, HAI-1, and c-Met were examined by Northern blotting and immunohistochemistry. RESULTS: Pro-HGF, but not mature HGF, was detected in normal gastric mucosa. When gastric mucosal injuries were induced, the expression of HGF significantly increased, and immunostaining of HGF was detected in fibroblasts in the gastric mucosa. In addition, conversion to mature HGF was observed in the injured gastric tissues, and mature HGF continued to increase for 48 h. HGFA was stably expressed in monkey livers, regardless of HCl administration. HAI-1 expression was detected in normal gastric mucosa, and its levels decreased after the induction of gastric mucosal injury. CONCLUSIONS: These results indicate that pro-HGF is stored in normal gastric tissues, and suggest that its conversion to mature HGF, associated with HGFA and HAI-1, is important for the repair of gastric mucosal injury.

Animals↗
PubMed1994

Oxygenation of polyunsaturated fatty acids by cytochrome P450 monooxygenases.

Polyunsaturated fatty acids can be oxygenated by P450 in different ways--by epoxidation, by hydroxylation of the omega-side chain, by allylic and bis-allylic hydroxylation and by hydroxylation with double bond migration. Major organs for these oxygenations are the liver and the kidney. P450 is an ubiquitous enzyme. It is therefore not surprising that some of these reactions have been found in other organs and tissues. Many observations indicate that P450 oxygenates arachidonic acid in vivo in man and in experimental animals. This is hardly surprising. omega-Oxidation was discovered in vivo 60 years ago. It was more unexpected that biological activities have been associated with many of the P450 metabolites of arachidonic acid, at least in pharmacological doses. Epoxygenase metabolites of arachidonic acid have attracted the largest interest. In their critical review on epoxygenase metabolism of arachidonic acid in 1989, Fitzpatrick and Murphy pointed out some major differences between the PGH synthase, the lipoxygenase and the P450 pathways of arachidonic acid metabolism. Their main points are still valid and have only to be modified slightly in the light of recent results. First, lipoxygenases show a marked regiospecificity and stereospecificity, while many P450 seem to lack this specificity. There are, however, P450 isozymes which catalyse stereospecific epoxidations or hydroxylations. Many hydroxylases and at least some epoxygenases also show regiospecificity, i.e. oxygenate only one double bond or one specific carbon of the fatty acid substrate. In addition, preference for arachidonic acid and eicosapentaenoic acid may occur in the sense that other fatty acids are oxygenated with less regiospecificity. A more important difference is that prostaglandins and leukotrienes affect specific and well characterised receptors in cell membranes, while receptors for epoxides of arachidonic acid or other P450 metabolites have not been characterised. Nevertheless, epoxides of arachidonic acid have been found to induce a large number of different pharmacological effects. In some systems, effects have been noted at pm concentrations which might conceivably be in the physiological concentration range of these epoxides, e.g. after release from phospholipids by phospholipase A2. An intriguing possibility is that the effects of [Ca]i on different ion channels might possibly explain their biological actions. In situations when pharmacological doses are used, metabolism to epoxyprostanoids or other interactions with PGH synthase could also be of importance. Finally, one report on a specific receptor for 14R,15S-EpETrE in mononuclear cell membranes has just been published.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Morphological changes of poly(ethylene terephthalate) on multiple steam sterilization.

Poly(ethylene terephthalate) (PET) was steam sterilized by autoclaving for 15, 30 and 60 min. The thermal properties, T m, delta-H and percent crystallinity were determined using differential scanning calorimetry. Molecular weight distribution was determined using gel permeation liquid chromatography. Crystallinity of PET was also monitored by infrared spectrophotometry. The analyses indicate that that chain scission and cyclization reactions take place in PET, forming cyclic oligomers, that can migrate to the polymer surface and which may affect long term performance of PET.

Calorimetry, Differential Scanning↗
PubMed1993

Fatty acid and lipid composition in vitro and in vivo of rat epidermis.

1. Fatty acid and lipid compositions of cultured rat keratinocytes were compared with those of intact epidermis prepared from newborn and adult rats. 2. The uniqueness of the lipid profile of cultured cell manifested itself in the accumulation of a novel lipid which co-migrated with monoalkyldiacylglyceride on thin-layer chromatography. 3. Concentration of the branched-chain fatty acid was specifically high in the cholesterol ester fraction of the intact cell, and was decreased by cultivation under submerged conditions.

Aging↗