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At least 73 records · Page 4Linked to original sources
PubMed2006

Fetal ocular movements and retinal cell differentiation: analysis employing DNA microarrays.

As developmental biologists we study the role of fetal movements in providing continuity between prenatal and postnatal life. There are two major categories of fetal motility. The first category consists of movements that have an obvious effect on the survival or development of the fetus (e.g., changes of position, sucking and swallowing). The second category consists of fetal movements that anticipate postnatal functions. For example, fetal ocular movements (FOMs) predict postnatal eye function (e.g., motion vision) of the newborn and therefore represent an important indicator of fetal health. However, while the clinical significance of fetal motility is obvious, its biological significance is elusive. We propose to use retina of genetically modified mouse embryos to study the biological role of FOMs in the genesis of cell diversity and organ functional maturation. Our results have already demonstrated the importance of fetal eye motility in the differentiation of cholinergic amacrine cells (CACs) in the retina (Kablar, 2003). Apparently, these cells are sensitive to motion and also responsible for motion vision. In the current report, we suggest employing the unique opportunity provided by the mouse Myf5-/-:MyoD-/- knock-outs that lack skeletal musculature and FOMs, microarray analysis and the follow-up experiments to identify a group of candidate genes that are essential for the molecular regulation of CAC differentiation and in turn for the functional maturation of the visual system towards its ability to perform motion vision. Finally, the molecules identified via this approach may be important in the mechanochemical signal transduction pathways employed during the process of conversion of a mechanical stimulus into an instruction understandable by the developing retinal neurons and glia cells.

Animals↗
PubMed2004

Differential analysis in the time domain of the baroreceptor cardiac reflex sensitivity as a function of sequence length.

Analysis of baroreceptor sensitivity (BRS) in the time domain through the spontaneous sequence method used a measure of BRS based on the average of all sequences detected, without making any distinction in cardiac cycle length. In this article, we study differentially the functioning of the baroreflex as a function of the length of the cardiac sequences (3, 4, 5, or 6 cardiac cycles). One hundred and four students performed three mental stress tasks: mental arithmetic, memory, and visual attention. The results show that (1) as sequence length decreases, the relationships between BRS and indexes of vagal cardiac control increase, (2) the BRS associated with the more short sequences (3 and 4 beats) is the most vulnerable to mental stress, particularly the mental arithmetic task, and (3) BRS increases progressively as sequence length decreases. These results suggest that the nature and functioning of the baroreflex differ as a function of the length of the cardiac sequences.

Adolescent↗
PubMed1996

Single-strand conformational polymorphism analysis differentiates Plasmodium falciparum treatment failures from re-infections.

Paired primary and recrudescent Plasmodium falciparum isolates were collected from treatment failures identified during the course of antimalarial drug studies on the Thai-Cambodian border. Ten paired samples were subjected to PCR-restriction fragment length polymorphism (RFLP) and PCR-single-strand conformational polymorphism (PCR-SSCP) analysis of the MSP-2 gene. PCR-SSCP analysis of paired samples demonstrated that each recrudescent isolate was identical to, or a subpopulation of, its matched primary isolate and was distinct from all unrelated isolates. This method represents a field applicable method to distinguish re-infections from treatment failures when antimalarial drug studies are performed in malaria-endemic areas.

Animals↗
PubMed2003

The shape operator for differential analysis of images.

This work provides a new technique for surface oriented volumetric image analysis. The method makes no assumptions about topology, instead constructing a local neighborhood from image information, such as a segmentation or edge map, to define a surface patch. Neighborhood constructions using extrinsic and intrinsic distances are given. This representation allows one to estimate differential properties directly from the image's Gauss map. We develop a novel technique for this purpose which estimates the shape operator and yields both principal directions and curvatures. Only first derivatives need be estimated, making the method numerically stable. We show the use of these measures for multi-scale classification of image structure by the mean and Gaussian curvatures. Finally, we propose to register image volumes by surface curvature. This is particularly useful when geometry is the only variable. To illustrate this, we register binary segmented data by surface curvature, both rigidly and non-rigidly. A novel variant of Demons registration, extensible for use with differentiable similarity metrics, is also applied for deformable curvature-driven registration of medical images.

Algorithms↗
PubMed2004

Epigenomic changes during leukemia cell differentiation: analysis of histone acetylation and cytosine methylation using CpG island microarrays.

Dysregulation of epigenetic control is an important participant in carcinogenesis. The PML/RAR alpha translocation in acute promyelocytic leukemia (APL) is an example where the resultant fusion protein recruits histone deacetylase complexes to target genes resulting in their inappropriate transcriptional repression. All-trans-retinoic acid (ATRA) acts as a ligand that relieves this repression and produces an epigenetic transcriptional reprogramming of the cancer cell. CpG island microarrays were used to analyze the DNA methylation and histone acetylation state of the human APL cell line NB4 before and after differentiation with ATRA as well as normal peripheral blood mononuclear cells (PBMC). Over 70 CpG islands within 1 kb of transcription start of a known gene are aberrantly methylated in NB4 cells compared with PBMC; however, no changes in cytosine methylation were detected following ATRA-induced differentiation. With respect to histone H4 acetylation, over 100 single-copy CpG islands within 1 kb of transcription start of a known human gene became hyperacetylated following ATRA-induced differentiation. One CpG island was aberrantly methylated in NB4 cells, but became hyperacetylated and was induced following ATRA treatment and was associated with the HoxA1 gene, suggesting it may be a target gene of ATRA in APL. In addition to single-copy sequences, a selective increase in acetylation was detected in satellite DNA when compared with other high-copy sequences, such as Alu or rDNA. In summary, ATRA stimulates complex epigenomic changes during leukemic cell differentiation, and monitoring these changes may help to identify new targets of epigenetic dysfunction.

Acetylation↗
PubMed1982

From three to 3: a differential analysis of skills in transcoding quantities between patients with Broca's and Wernicke's aphasia.

A psycholinguistic investigation into the ability of aphasic patients to transcode integer quantities from written numeral forms into digit strings is reported. Broca's aphasics experienced specific difficulties in handling the grammatical structure underlying word order and also, on the word level, the bound morphemes relative to the root morphemes. Wernicke's aphasics seemed to have lexical troubles reflected by some purely lexical confusions together with serial order disturbances. These findings support the hypothesis of differential preserved/impaired skills according to type of aphasia, but having a high level of generality since they appear in classic linguistic tasks as well as in the domain of numbers.

Adult↗
PubMed1980

Differential analysis of selected prompts and neurological variables in motor assessment of moderately mentally retarded children.

The purpose of this study was to elevate the specificity of gross-motor assessment strategies presently used with moderately mentally retarded children by measuring voluntary motor performance as a function of level of reflex development, level of orthopedic functioning, and type of prompts used in test instructions. After clinically assessing subjects' levels of reflex and orthopedic functioning, we randomly assigned subjects to multisensory-, physical-, modeling-, and verbal-prompt treatment groups. Multisensory prompts and differential use of selected prompts were effective with younger and older children, respectively. A significant interrelationship was found between subjects' levels of reflex development and voluntary motor performance.

Adolescent↗
PubMed2005

The international consensus group for hematology review: suggested criteria for action following automated CBC and WBC differential analysis.

In the half century since the first use of automated analyzers, manual techniques, especially microscopic examination of a stained blood film, have complemented analyzer results to provide a comprehensive hematology report on a patient's blood sample. Over the years, as the capabilities and performance of automated analyzers have improved, the respective roles of the automated analyzer and the complementary procedures have changed. Manual action (most commonly smear review) following automated analyzer results is usually triggered by determining whether the results trigger one of a series of criteria for review of results. There is little uniformity among different laboratories on criteria for action. Recognizing the long-standing need for generally accepted guidelines ("rules") which could be applied to criteria for review of CBC and differential results from automated hematology analyzers, Dr. Berend Houwen invited 20 experts to a meeting in the Spring of 2002 to discuss the issues and determine the most appropriate criteria. At this meeting, 83 rules were developed by consensus agreement. These rules were then tested in 15 laboratories on a total of 13,298 blood samples. After a detailed analysis of the data, the rules were refined and consolidated to produce 41 rules that are presented here. They include rules for first-time samples as well as delta rules for repeat samples within 72 hours from a patient. It is hoped that these rules will be useful to a large number of hematology laboratories worldwide. To facilitate validating these rules in individual laboratories before implementation in routine operation for patient samples, a suggested protocol is attached to this paper.

Automation↗
PubMed2005

Scaling up a microbore separation for semipreparative analysis: differential recoveries of radiolabeled amino acids.

Application of a high-sensitivity microbore system designed to separate and quantify nonderivatized amino acids by anion exchange chromatography and amperometric detection for determination of amino acid-specific activities in biological samples requires high capacity to recover sufficient labeled material for adequate count statistics. Scale up from a low (25-1000 pmol) to a high (500-15,000 pmol) working range was achieved by use of a thick working electrode gasket to reduce sensitivity and eliminate peak splitting and tailing and by modification of the wash procedure to eliminate carryover. Analysis of recoveries of labeled amino acids revealed that specific amino acids are either selectively retained on the column or partially degraded during analysis and that assessment of purities of labeled compounds and metabolic labeling patterns requires careful analysis of recoveries of labeled compounds in the appropriate eluate fraction.

Amino Acids↗
PubMed2004

Proteome analysis differentiates between two highly homologues germin-like proteins in Arabidopsis thaliana ecotypes Col-0 and Ws-2.

A proteome approach based on 2-D gel electrophoresis (2-DE) was used to compare the protein patterns of the Arabidopsis ecotypes Col-0 and Ws-2. In leaf extracts a pair of protein spots were found to be diagnostic for each of the lines. Both pairs of spots were identified as closely related germin-like proteins differing in only one amino acid by using peptide mass finger printing of tryptic digests and by gaining additional data from post-source decay spectra in the MALDI-TOF analysis. Western blot analysis after separation of protein extracts by 2-DE confirmed results from Coomassie blue-stained gels and revealed additional immunoreactive spots for both ecotypes most likely representing dimers of the spots first identified. Western blot analysis and mass spectrometrical identification of the corresponding weakly stained protein in Coomassie blue-stained gels of the ecotype Col-0 also demonstrated for the first time the occurrence of AtGER3 protein in root extracts. Our results demonstrate the capacity of proteome analysis to analyse and distinguish closely related members of large protein families.

Amino Acid Sequence↗
PubMed1984

Relationship between cell surface asparagine-linked glycoproteins and myoblast differentiation. Analysis of wheat germ agglutinin-resistant mutants.

Alterations in the oligosaccharides of complex surface glycoproteins have been studied in wild-type rat skeletal myoblasts (L6-9/1) and two wheat germ agglutinin resistant mutants, selected for either high level of resistance (WGARI) or low level of resistance (WGARII). All three lines possessed high mannose oligosaccharides of the structure Man(n)GlcNAc, where n = 6, 7, or 8. L6-9/1 had complex oligosaccharides of the type (+/- NeuNAc alpha 2-3Gal beta GlcNAc beta)n-Man3GlcNAc(+/- Fuc)GlcNAc where n = 3 or 4, in addition to small amounts of biantennary and higher order structures. WGARII, the mutant with low resistance to wheat germ agglutinin, possessed similar complex oligosaccharides except that they had undergone some base-sensitive modification which rendered them resistant to Clostridium perfringens sialidase. WGARI, mutant of high resistance to wheat germ agglutinin, possessed complex oligosaccharides of the type (GlcNAc beta)nMan3GlcNAc(+/- Fuc)GlcNAc, with n = 2, 3, or 4. Since the WGARI mutants were unaltered in differentiation, it is concluded that the terminal sialic acid and galactose residues on the protein-bound oligosaccharides are not required for differentiation.

Animals↗
PubMedDate not supplied

Differential analysis of behavior and diazepam-induced alterations in C57BL/6N and BALB/c mice using the modified hole board test.

A variety of test procedures are used in preclinical research on behavioral pharmacology and to dissociate behavioral differences or pharmacologically induced behavioral alterations several independent tests are usually performed. In the present study we introduce a modified hole board procedure for mice which allows us to investigate a variety of behavioral parameters such as anxiety, risk assessment, exploration, locomotion, food-intake inhibition, novelty seeking, and arousal by using only one test. The modified hole board was established by investigating the behavior of two inbred mouse strains, C57BL/6 and BALB. Significant differences in terms of locomotor activity, general exploration, and other parameters were found. Moreover, strain-specific exploration strategies could be detected in the modified hole board. Further, the test was validated by investigating the effects of diazepam as standard anxiolytic on the behavior in both mouse strains. Acute administration of diazepam (1 and 3 mg/kg) induced strong sedative effects in a dose-dependent manner in C57BL/6 mice. In BALB mice, the lower dosage of diazepam showed an activating and anxiolytic action while the 3 mg dosage revealed a slight sedative but still anxiolytic effect in these animals. Taken together, the results demonstrate that the modified hole board enables to differentially investigate behavioral phenotypes and also pharmacologically-induced behavioral alterations in mice. Therefore, this new strategy allows to reduce the number of experimental animals and the time needed, thus, representing an effective screening-tool for behavioral investigations.

Animals↗
PubMed2004

Differential analysis of CD4+ Th memory clones with identical T-cell receptor (TCR)-alphabeta rearrangement (non-transgenic), but distinct lymphokine phenotype, reveals diverse and novel gene expression.

This study describes a subtractive hybridization analysis to identify differences in gene expression between sibling Th memory clones, elicited by virus infection and expressing identical T-cell receptor (TCR)-alphabeta rearrangements but distinct lymphokine phenotype: clone Bpp9 secretes interleukin (IL)-4, IL-5 and IL-10; clone Bpp19 secretes interferon (IFN)-gamma, low levels of IL-4, and IL-5 on TCR ligation. cDNA sequencing of difference products (DP) identified both novel and known regulatory (DNA: RNA-binding) or signalling proteins (kinases: phosphatases). Of the 10 novel genes identified, three were putative membrane proteins, one a predicted nuclear protein containing a PEST sequence motif, one a predicted transporter fragment and one contained a zinc-finger motif. One of the membrane proteins was found only in RNA from the activated IFN-gamma-producing clone, i.e. not in other tissues. In addition, a high frequency of granzyme A, B, C and G transcripts (for clone Bpp9) or transcripts for CD94 and NKG2A (for clone Bpp19) were expressed differentially, together with transcripts that mapped to, so far, unassigned regions of the mouse genome that may be further novel genes. The transcriptional profiles presented here may therefore include candidate regulators of Th diversity and effector function.

Animals↗
PubMed1990

Differential analysis of the frequency-dependent effects of class 1 antiarrhythmic drugs according to periodical ligand binding: implications for antiarrhythmic and proarrhythmic efficacy.

The frequency-dependent block of cardiac sodium channels by class 1 antiarrhythmic drugs can be described by a periodical ligand binding process between drug molecules and channel binding sites. This predicts a linear relation between onset-rate constant of frequency-dependent block and diastolic interval as well as saturation of block with high stimulation rates. From both relationships, the binding kinetics (time constant, tau on) and saturation level of block (bdinf) can be estimated. This is exemplified for the frequency-dependent block (reduction of the maximal upstroke velocity of action potentials) induced by prajmaline (10(-6) M). In the same way, the frequency-dependent effects of 11 other class 1 drugs reported in the literature were analyzed and compared with each other. When the drugs are ranked with respect to their binding kinetics (tau on), there is a close relationship to the subclasses (1a, 1b, 1c), with 1b drugs exhibiting the fastest and 1c drugs the slowest kinetics. However, differences also exist in the saturation behavior of frequency-dependent block even within the same subclasses (1a and 1c). Thus, the class 1 drugs can also be subdivided in three other groups exhibiting clearly separated bands of block-frequency relations, with half-maximal saturation occurring at different stimulation rates. Our findings may have differential implications for the antiarrhythmic and proarrhythmic efficacy of class 1 drugs.

Animals↗