Thermal behaviours in dental Ni-base casting alloys (part 1). Differential thermal analysis.
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Dental Alloys↗
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Differential thermal analysis of dipalmitoylphosphatidylcholine--fatty acid mixtures.
Mixtures of dipalmitoylphosphatidylcholine (DPPC) with palmitic, stearic, and myristic acids and the sodium salts of these acids were analyzed by differential thermal analysis (DTA) over a wide range of lipid compositions, all in excess water. All three fatty acids raise the liquid-crystal phase transition temperature and form sharp-melting complexes, with 1:2 DPPC--fatty acid stoichiometry observed for palmitic and stearic acids and suggested for myristic acid. Phase diagrams of the peritectic type, indicating nonideal mixing, was fitted to the DPPC--palmitic acid and DPPC--stearic acid data. In contrast, DPPC forms nearly ideal mixtures with the putative DPPC--myristic acid complex. At levels of only a few mole percent, both sodium stearate and myristate remove the pretransition and main transition and produce new peaks at approximately 30 and approximately 48 degrees C; the relative areas of the new peaks were unreproducible for the DPPC--myristate system. Sodium palmitate is the least disruptive of any of the sodium soaps or fatty acids; up to 80 mol % palmitate, the transition is lowered 3 degrees C and approximately doubled in width. The pretransition is detectable up to 36 mol %, and the main transition persists up to 88 mol % palmitate. The apparent pK of palmitic acid (12 mol %) in DPPC bilayers was determined to be 10.2 by direct pH measurement of ternary DPPC mixtures with known palmitic acid/sodium palmitate ratios; the intrinsic pK is estimated to be less than or approximately 8.5.
Fatty Acids, Nonesterified↗
Organization of the membrane skeleton in spreading mouse blastomeres. I. Morphological analysis.
Differentiation in the mouse embryo begins at the 8-cell stage when the blastomeres spread against each other in a process called compaction. The spreading behavior of blastomeres on lectin-coated coverslips mimics that of blastomeres in the embryo, and we have utilized this model system to obtain an en face view of the membrane skeleton in the spreading blastomeres. Embryos were cultured on the coverslips for periods ranging from 20 sec to 6 hr, and the cells were disrupted to expose the cytoplasmic face of the adherent membranes and their associated filaments. The "membrane lawn" preparations were fixed, critical point dried, rotary shadowed, and the replicas examined by transmission electron microscopy. Using this technique we found that the plasmalemma of rounded blastomeres is associated with a lacy 3-dimensional filamentous meshwork that is transformed into a thin mat of densely woven filaments when the cells flatten. The overall organization of the membrane skeleton is similar in flattening 2- and 8-cell embryos, but there are significant differences in the time required for spreading to take place, in the means whereby the membrane skeletons are reorganized, and in the extent of maximal flattening. The significance of these observations for the compaction process is discussed.
Animals↗
Compatibility studies between ibuprofen or ketoprofen with cellulose ether polymer mixtures using thermal analysis.
Differential scanning calorimetry (DSC) was used to investigate and detect incompatibilities between drugs such as: ibuprofen (IBU) or ketoprofen (KETO) with cellulose ether derivatives, which are frequently applied on controlled release dosage forms. Binary mixtures concerning methylcellulose (MC25) or hydroxypropylcellulose (HPC) with hydroxypropylmethylcellulose (HPMC) K15M or K100M in different ratios were prepared and evaluated by the appearance, shift, or disappearance of peaks and/or variations in the corresponding DeltaH values. According to the DSC results, binary mixtures between those polymers were found to be compatible, but their mixture with IBU or KETO, promotes a solid-solid interaction mainly with 1:1:1 (w/w) ratio (drug-excipient). However, when the drug:excipient interactions were detected, they were not found to affect the drug bioavailability. DSC was successfully employed to evaluate the compatibility of the drugs with the selected polymers.
Anti-Inflammatory Agents, Non-Steroidal↗
Urodynamic analysis of differential sacral nerve blocks and sacral neurectomy.
Urodynamic analysis in 17 patients after long-acting anaesthetic root blocks of S2-S4 has shown that it is possible to increase bladder capacity and reduce uninhibited contractions without significant adverse effects on sphincter function. Satisfactory voiding dynamics are observed after blocks. This has provided a physiological rationale for selective sacral neurectomy in eight patients. Initial improvement after operation has been noted in seven cases.
Anesthesia, Conduction↗
Calcitonin gene-related peptide containing sensory neurons innervating tooth pulp and buccal mucosa of the rat: an immunohistochemical analysis.
Differential peptidergic innervation of the rat buccal mucosa and incisor tooth pulp was demonstrated by experimental immunohistochemistry. In the buccal mucosa, calcitonin gene-related peptide (CGRP)-like immunoreactive (IR) nerve fibres were observed in both the epithelium and submucosal layer. Most of these fibres were also immunoreactive to substance P (SP). On the other hand, SP-IR fibres were less numerous than CGRP-IR fibres in the incisor tooth pulp. Fast blue (FB) was applied to the buccal mucosa and the incisor pulp chamber. Small (less than 20 microns) FB-labelled CGRP-IR neurons were more numerous in the buccal mucosa group, while medium to large neurons (20-50 microns) predominated in the incisor pulp. Following neonatal capsaicin treatment, CGRP- and SP-containing fibres in the buccal mucosa almost totally disappeared, but many CGRP-IR fibres remained in the incisor tooth pulp. The findings suggest that these two oral tissues are innervated by different subgroups of CGRP-IR neurons in the trigeminal ganglia.
Animals↗
Analysis of differential messenger RNA expression between bovine blastocysts produced in different culture systems: implications for blastocyst quality.
Using reverse transcriptase-amplified fragment length polymorphism (RT-AFLP) analysis of differential mRNA expression and semiquantitative reverse transcriptase-polymerase chain reaction, we compared mRNA expression in bovine blastocysts from 4 sources, known to differ in quality in terms of their ability to withstand cryopreservation: 1) in vitro culture in synthetic oviduct fluid of in vitro-matured (IVM)/in vitro fertilized (IVF) zygotes; 2) in vitro culture in TCM-199 supplemented with granulosa cells (coculture) of IVM/IVF zygotes; 3) in vivo culture in the ewe oviduct of IVM/IVF zygotes; or 4) superovulation, artificial insemination, and nonsurgical embryo recovery. Total mRNA was isolated from pools of blastocysts and reverse transcription was performed. Triplicate reactions from each sample were displayed, and only consistent banding variations were recorded. Using AFLP-differential display assay, we found that cDNA banding patterns are highly conserved between the 4 groups of blastocysts studied; however, there was a difference of 7% in bands either missing or expressed across the groups. Fifty bands were reamplified, and a sequence comparison search revealed similarity of 14 isolated fragments to ribosomal and mitochondrial genes, 16 matched to described cDNA, and 20 corresponded to unknown sequences that may represent novel genes. The study of 7 differentially expressed mRNAs known to be involved in developmental process in the embryo suggests roles for apoptosis, oxidative stress, gap junctions, and differentiation in the determination of embryo quality. The aberrant transcription patterns detected in in vitro-produced bovine embryos compared with those produced in vivo may explain their reduced quality in terms of viability after cryopreservation.
Animals↗
Use of restriction fragment length polymorphism analysis to differentiate strains of psychrophilic and psychrotropic clostridia associated with blown pack' spoilage of vacuum-packed meats.
Reference and meat strains of psychrophilic and psychrotrophic clostridia were differentiated using restriction fragment length polymorphism (RFLP) analysis of genomic DNA (DNA-RFLP) and the polymerase chain reaction-amplified 16S rDNA gene (PCR-RFLP). Groupings obtained with PCR-RFLP were confirmed with 16S rDNA gene sequencing. DNA-RFLP resolved 19 of the 22 meat strains into 11 groups. Three meat strains were untypable using this method. All reference strains representing different genotypic species could be distinguished by the restriction patterns of 16S rDNA genes. With PCR-RFLP, the 22 meat strains produced eight distinct genotypes. 16S rDNA gene sequencing confirmed that each genotype was represented by a distinct sequence. PCR-RFLP restriction patterns of 15 meat strains matched those of one of two of the seven reference strains used. Seven meat strains whose RFLP restriction patterns of 16S rDNA genes differed from those of any reference strains probably represent four previously undescribed species. Although RFLP analysis of the amplified 16S rDNA gene allowed differentiation of psychrophilic and psychrotrophic clostridia at the genotypic species level and below, comparison of PCR-RFLP patterns and 16S rDNA sequences of unknown clostridial isolates with patterns and sequences of reference strains may not effect ready identification of these micro-organisms. The results of this study will be useful in diagnosis of the cause of premature spoilage of chilled vacuum-packed meats and in tracing spoilage-causing clostridia to their source(s) in the abattoir.
Clostridium↗
Pressure study on thermal transitions of oleic acid polymorphs by high-pressure differential thermal analysis.
Transition temperatures for oleic acid polymorphs (alpha, beta and gamma) and the melt were measured under various pressures up to 200 MPa by means of high-pressure differential thermal analysis. The pressure dependences of the transition temperatures were analyzed by applying the Clapeyron equation, and the volume changes associated with the phase transitions were estimated as follows; delta V gamma-alpha = 5.9 cm3/mol, delta V alpha-melt = 29.2 cm3/mol and delta V beta-melt = 41.1 cm3/mol. The volume changes for the gamma-alpha and alpha-melt transitions were discussed in relation to the crystal structures of the alpha and gamma modifications. The experiments showed that the beta modification, whose structural data are lacking, is the most dense. This correlates with the fact that the beta form is thermodynamically most stable among the three modifications of oleic acid.
Alkanes↗
[Diagnosis of swine dysentery and spirochaetal diarrhea. 2. Effort of macrorestriction analysis for differentiation of intestinal Serpulina relative to determination by culture-biochemical markers following species classification].
Genotypic differentiation by means of macrorestriction fragment profile analysis using Mlul restriction enzyme was carried out differentiating 41 Serpulina field strains from swine (38), dog (2) and a rat as well as ten type and reference strains into 40 electrophoretic types. A dendrogram was created using the average linkage between groups method. At a level of 50% similarity the patterns could be divided into six groups that roughly corresponded to the results yielded by cultural and biochemical methods formerly (FELTRUP et al. 1999). Five of these clusters corresponded to the five known porcine Serpulina species, one cluster contained the S. pilosicoli isolates from dog and rat included in this study. Interestingly all nine investigated indole negative, strongly haemolytic isolates were clustered together in one group with the S. hyodysenteriae strains, so that incidence of indole negative variants of S. hyodysenteriae was confirmed. Because of being grouped together with two S. intermedia isolates, the suitability of B 256 as S. innocens type strain is--in accord to investigations carried out by PETTERSSON et al (1996)--called in question.
Animals↗
RT-PCR heteroduplex analysis permits differentiation of transgene and host gene expression in a transgenic animal model.
In transgenic animal models, the conservation of DNA sequences between the transgene and the host wild-type gene can complicate the evaluation of the expression of each gene. The potential for gene silencing may complicate matters further. Here we report the use of RT-PCR heteroduplex analysis to differentiate the expression of a transgene and its homologous wild-type, even when these genes are very similar in their respective DNA sequences. We designed RT-PCR primers to amplify identically sized 243-bp fragments within the DNA binding domain of the p53 gene from both human and mouse mRNA samples. Ten samples from human p53 (273H) transgenic mice and 10 samples from wild-type controls were tested. Heteroduplex bands were formed in all transgenic samples but were absent from all wild-type samples. In addition, RT-PCR heteroduplex analysis was able in one sample to differentiate a silenced transgene from its wild-type allele, without the assistance of sequencing or labeling. In summary, the RT-PCR heteroduplex analysis is easy to use and has the ability to screen a large number of samples in a short time. The RT-PCR heteroduplex analysis is especially useful for the detection of expression when a transgene and the host homologous endogenous allele are too conserved in sequence to design species-specific RT-PCR primers.
Animals↗
[Differential thermal analysis of the organic fraction of bone].
Thermal decomposition analysis of Bovine femur bone has been carried out by means of a Micro Differential Thermal Analyser. The analysis of both thermograms and amino acid compositions has revealed the complexity of collagen degradation mechanisms.
Amino Acids↗
Microarray analysis of differential gene expression in lead-exposed astrocytes.
The toxic metal lead is a widespread environmental health hazard that can adversely affect human health. In an effort to better understand the cellular and molecular consequences of lead exposure, we have employed cDNA microarrays to analyze the effects of acute lead exposure on large-scale gene expression patterns in immortalized rat astrocytes. Our studies identified many genes previously reported to be differentially regulated by lead exposure. Additionally, we have identified novel putative targets of lead-mediated toxicity, including members of the family of calcium/phospholipid binding annexins, the angiogenesis-inducing thrombospondins, collagens, and tRNA synthetases. We demonstrate the ability to distinguish lead-exposed samples from control or sodium samples solely on the basis of large-scale gene expression patterns using two complementary clustering methods. We have confirmed the altered expression of candidate genes and their encoded proteins by RT-PCR and Western blotting, respectively. Finally, we show that the calcium-dependent phospholipid binding protein annexin A5, initially identified as a differentially regulated gene by our microarray analysis, is directly bound and activated by nanomolar concentrations of lead. We conclude that microarray technology is an effective tool for the identification of lead-induced patterns of gene expression and molecular targets of lead.
Amino Acyl-tRNA Synthetases↗
Down modulation of fibronectin messenger RNA in metastasizing rat prostatic cancer cells revealed by differential hybridization analysis.
To identify genes whose expression is down modulated in the process of metastasis, gene expression was analyzed in cell lines derived from Dunning R-3327 rat prostatic tumor sublines. A complementary DNA (cDNA) library from the anaplastic nonmetastasizing subline AT-1 was used for a differential hybridization analysis, using probes derived from mRNAs of the AT-1 and the metastasizing MAT-LyLu subline. In this way 14 cDNA clones were isolated representing 6 differentially expressed genes. The expression levels in a panel of tumor sublines measured with these cDNA clones were tested for correlation with the anaplastic non-metastasizing phenotype. One cDNA clone, designated pSE-1, whose expression was high in all tested sublines with that phenotype, appeared to represent the gene for fibronectin. To further investigate the down modulation of this gene, we studied its expression in AT-2 (anaplastic, nonmetastasizing tumor) and lines derived therefrom that exhibited a high metastatic potential after transfection with the v-Ha-ras oncogene. In the genetically manipulated metastasizing tumor sublines, fibronectin mRNA levels were approximately 4- to 8-fold lowered compared to the nonmetastasizing parental AT-2 line.
Animals↗
Analysis of differentially expressed genes in human hepatocellular carcinoma using suppression subtractive hybridization.
The genetic basis of hepatocellular carcinoma (HCC) has not yet been fully understood. Although various methods have been developed to detect differentially expressed genes in malignant diseases, efficient analysis from clinical specimens is generally difficult to perform due to the requirement of a large amount of samples. In the present study, we analysed differentially expressed genes with a small amount of human HCC samples using suppression subtractive hybridization (SSH). Total RNA were obtained from the hepatitis C virus-associated HCC and adjacent non-HCC liver tissues. cDNA was synthesized using modified RT-PCR, and then tester cDNA was ligated with 2 different kinds of adaptors and hybridized with an excess amount of driver cDNA. Tester specific cDNA was obtained by suppression PCR and the final PCR product was subcloned and sequenced. We identified 7 known genes (focal adhesion kinase, deleted in colon cancer, guanine binding inhibitory protein alpha, glutamine synthetase, ornithine aminotransferase, M130, and pepsinogen C) and 2 previously unknown genes as being overexpressed in HCC, and 1 gene (decorin) as suppressed in HCC. Quantitative analysis of gene expression using quantitative RT-PCR demonstrated the differential expression of these genes in the original and other HCC samples. These findings demonstrated that it is possible to identify the previously unknown, differential gene expression from a small amount of clinical samples. Information about such alterations in gene expression could be useful for elucidating the genetic events in HCC pathogenesis, developing the new diagnostic markers, or determining novel therapeutic targets.
Amino Acid Sequence↗
Differential thermal analysis of aluminum hydroxide gel.
The development of order during the aging of aluminum hydroxide gel prepared by the reaction of aluminum chloride and ammonium hydroxide to a final pH of 7.0 can be monitored by differential thermal analysis. The loss of acid reactivity upon aging is accompanied by an increase in the temperature and intensity of the dehydroxylation endotherm and an accompanying decrease in the intensity of the water of hydration endotherm. With continued aging, the thermogram develops the characteristics of a crystalline aluminum hydroxide.
Aluminum Hydroxide↗
Differential proteome analysis of replicative senescence in rat embryo fibroblasts.
Normal somatic cells undergo a finite number of divisions and then cease dividing whereas cancer cells are able to proliferate indefinitely. To identify the underlying mechanisms that limit the mitotic potential, a two-dimensional differential proteome analysis of replicative senescence in serially passaged rat embryo fibroblasts was undertaken. Triplicate independent two-dimensional gels containing over 1200 spots each were run, curated, and analyzed. This revealed 49 spots whose expression was altered more than 2-fold. Of these, 42 spots yielded positive protein identification by mass spectrometry comprising a variety of cytoskeletal, heat shock, and metabolic proteins, as well as proteins involved in trafficking, differentiation, and protein synthesis, turnover, and modification. These included gelsolin, a candidate tumor suppressor for breast cancer, and alpha-glucosidase II, a member of the family of glucosidases that includes klotho; a defect in klotho expression in mice results in a syndrome that resembles human aging. Changes in expression of TUC-1, -2, -4, and -4 beta, members of the TUC family critical for neuronal differentiation, were also identified. Some of the identified changes were also shown to occur in two other models of senescence, premature senescence of REF52 cells and replicative senescence of mouse embryo fibroblasts. The majority of these candidate proteins were unrecognized previously in replicative senescence. They are now implicated in a new role.
Animals↗
Homocysteine-respondent genes in vascular endothelial cells identified by differential display analysis. GRP78/BiP and novel genes.
An elevated blood level of homocysteine is associated with arteriosclerosis and thrombosis. The mechanisms by which homocysteine may promote vascular diseases have not been elucidated yet. In the present study, we have applied a modified nonradioactive differential display analysis to evaluate changes in gene expression induced by homocysteine treatment of cultured human umbilical vein endothelial cells (HUVEC). We identified six up-regulated and one down-regulated genes. One up-regulated gene was GRP78/BiP, a stress protein, suggesting that misfolded proteins would accumulate in the endoplasmic reticulum because of redox potential changes caused by homocysteine. Another up-regulated gene encoded a bifunctional enzyme with activities of methylenetetrahydrofolate dehydrogenase and methenyltetrahydrofolate cyclohydrolase, which is involved in a homocysteine metabolism. A third up-regulated gene encoded activating transcription factor 4, and a fourth was a gene whose function is not identified yet. The remaining three were novel genes. We isolated a full-length cDNA of one of the up-regulated genes from a HUVEC library. It encoded a novel protein with 394 amino acids, which was termed reducing agents and tunicamycin-responsive protein (RTP). Northern blot analysis revealed that RTP gene expression was induced in HUVEC after 4 h incubation with homocysteine. RTP mRNA was also observed in unstimulated cells and induced by not only homocysteine but also 2-mercaptoethanol and tunicamycin. The mRNA was ubiquitously expressed in human tissues. These observations indicate that homocysteine can alter the expressivity of multiple genes, including a stress protein and several novel genes. These responses may contribute to atherogenesis.
Amino Acid Sequence↗