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At least 775 records · Page 43Linked to original sources
PubMed2002

Functional analysis of gallbladder using three-dimensional ultrasound: preliminary results.

In evaluating gallbladder function, the clinical feasibility of three-dimensional (3-D) ultrasound (US) using volumetric acquisition was assessed in 30 patients: 18 patients with gallstones and 12 healthy volunteers. 3-D ultrasonography was performed in each patient before and after a fat-meal test. The ejection fraction of the gallbladder from two volumes measured by computer-aided analysis was calculated. There were significant differences in the gallbladder ejection fractions among the diseased and control groups (p < 0.0001). Compared with the results of oral cholecystograms, the ejection fraction of the gallbladder using 3-D volumetry and the grade of oral cholecystography showed good correlation in predicting the gallbladder dysfunction (gamma = 0.71, p = 0.002). Even in cases failing oral cholecystography, the gallbladder ejection fraction using 3-D US was calculated without any difficulty. Conclusively, volumetric acquisition of 3-D US enables us to evaluate gallbladder function and provides a reliable diagnostic yield superior to oral cholecystography.

Adult↗
PubMed2001

In vivo morphometry and functional analysis of human articular cartilage with quantitative magnetic resonance imaging--from image to data, from data to theory.

Analyses of form-function relationships and disease processes in human articular cartilage necessitate in vivo assessment of cartilage morphology and deformational behavior. MR imaging and advanced digital post-processing techniques have opened novel possibilities for quantitative analysis of cartilage morphology, structure, and function in health and disease. This article reviews work on three-dimensional post-processing of MR image data of articular cartilage, summarizing studies on the accuracy and precision of quantitative analyses in human joints. It presents normative values on cartilage volume, thickness, and joint surface areas in the human knee, and describes the correlation between different joints and joint surfaces as well as their association with gender, body dimensions, and age. The article summarizes ongoing work on functional adaptation of articular cartilage to mechanical loading, analyses of in situ cartilage deformation in intact joints in vivo and in vitro, and the quantitative evaluation of cartilage tissue loss in osteoarthritis. We describe evolving techniques for assessment of the structural/biochemical composition of articular cartilage, and discuss future perspectives of quantitative cartilage imaging in the context of joint mechanics, mechano-adaptation, epidemiology, and osteoarthritis research. Specifically, we show that fat-suppressed gradient echo sequences permit valid analysis of cartilage morphology, both in healthy and severely osteoarthritic joints, as well as highly reproducible measurements (CV%=1 to 3% in the knee, and 2 to 10% in the ankle). Relatively small differences in cartilage morphology exist between both limbs of the same person (approximately 5%), but large differences between individuals (CV% approximately 20%). Men display only slightly thicker cartilage then women (approximately 10%), but significantly larger joint surface areas (approximately 25%), even when accounting for differences in body weight and height. Weight and height represent relatively poor predictors of cartilage thickness (r2 <15%), but muscle cross section areas display more promising correlations (r2 >40%). The level of physical exercise (sportive activity) does not account for interindividual differences in cartilage thickness. The thickness appears to decrease slightly in the elderly--in particular in women, even in the absence of osteoarthritic cartilage lesions. Strenuous physical exercises (e.g., knee bends) cause a 6% patellar cartilage deformation in young individuals, but significantly less deformation in elderly men and women (<3%). The time required for full recovery after exercise (fluid flow back into the matrix) is relatively long (approximately 90 min). Static in situ compression of femoropatellar cartilage with 150% body weight produces large deformations after 4 h (approximately 30% volume change), but only very little deformation during the first minutes of loading. Quantitative analyses of magnetization transfer and proton density hold promise for biochemical evaluation of articular cartilage, and are shown to be related to the deformational behavior of the cartilage. Application of these techniques to larger cohorts of patients in epidemiological and clinical studies will establish the role of quantitative cartilage imaging not only in basic research on form-function relationships of articular cartilage, but also in clinical research and management of osteoarthritis.

Cartilage, Articular↗
PubMed2002

[Function analysis of a wheat phosphate transporter in yeast mutant].

Phosphorus is a major nutrient acquired by plants and phosphorus availability is considered one of the major growth-limiting factors for plants in many natural ecosystems. For a better understanding of the function of the wheat phosphorus transporter gene named TaPT2, we did Southern blot analysis and studied its function with complementation test in yeast mutant strain MB192. Southern blot indicated that TaPT2 gene is a low-copy member and has several different members in wheat genome. In the function complementation study, TaPT2 has a similar function as PHO84 which is the phosphate transporter in yeast Saccharomyces cerevisiae. Both TaPT2 and PHO84 are able to complement the PHO84 mutant phenotype of yeast strain MB192 which lacks the phosphate transporter activity. Therefor, this assessment presents evidence that TaPT2 gene plays an important role in Pi acquisition.

Blotting, Southern↗
PubMed2002

Structure-function analysis of NADE: identification of regions that mediate nerve growth factor-induced apoptosis.

Nerve growth factor (NGF) can induce apoptosis in neural cells via activation of the low affinity neurotrophin receptor p75NTR. NADE (p75NTR-associated cell death executor) is a p75NTR-associated protein that mediates apoptosis in response to NGF by interacting with the death domain of p75NTR in 293T, PC12, and nnr5 cells (Mukai, J., Hachiya, T., Shoji-Hoshino, S., Kimura, M. T., Nadano, D., Suvanto, P., Hanaoka, T., Li, Y., Irie, S., Greene, L. A., and Sato, T. A. (2000) J. Biol. Chem. 275, 17566-17570). We performed extensive mutational analysis on NADE, to better characterize its structural and functional features. Truncation of a minimal region, including amino acid residues 41-71 of NADE, was found to be sufficient to induce apoptosis. The designated regulatory region includes the C-terminal amino acid residues (72-112) and is essential for NGF-dependent regulation of NADE-induced apoptosis. Furthermore, the mutants with amino acid substitutions in the leucine-rich nuclear export signal (NES) sequence (residues 90-100) abolished the export of NADE from the nucleus to the cytoplasm. Mutation of the NES also abolished self-association of NADE, its interaction with p75NTR, and NGF-dependent apoptosis. Expression of a fragment of NADE (amino acid residues 81-124) blocked NGF-induced apoptosis in oligodendrocytes, suggesting that this region has a dominant negative effect on NGF/p75NTR-induced apoptosis. These studies identify distinct regions of NADE that are involved in regulating specific functions involved in p75NTR signal transduction.

Adenoviridae↗
PubMed2003

Functional analysis of nsP3 phosphoprotein mutants of Sindbis virus.

Alphavirus nsP3 phosphoprotein is essential for virus replication and functions initially within polyprotein P123 or P23 components of the short-lived minus-strand replicase, and upon polyprotein cleavage, mature nsP3 likely functions also in plus-strand synthesis. We report the identification of a second nsP3 mutant from among the A complementation group of Sindbis virus (SIN) heat-resistant strain, ts RNA-negative mutants. The ts138 mutant possessed a change of G4303 to C, predicting an Ala68-to-Gly alteration that altered a conserved His-Ala-Val tripeptide in the ancient (pre-eukaryotic), "X" or histone 2A phosphoesterase-like macrodomain that in SIN encompasses nsP3 residues 1 to 161 and whose role is unknown. We undertook comparative analysis of three nsP3 N-terminal region mutants and observed (i) that nsP3 and nsP2 functioned initially as a single unit as deduced from complementation analysis and in agreement with our previous studies, (ii) that the degree of phosphorylation varied among the nsP3 mutants, and (iii) that reduced phosphorylation of nsP3 correlated with reduced minus-strand synthesis. The most striking phenotype was exhibited by ts4 (Ala268 to Val), which after shift to 40 degrees C made significantly underphosphorylated P23/nsP3 and lost selectively the ability to make minus strands. After shift to 40 degrees C, mutant ts7 (Phe312 to Ser) made phosphorylated P23/nsP3 and minus strands but failed to increase plus-strand synthesis. Macrodomain mutant ts138 was intermediate, making at 40 degrees C partially phosphorylated P23/nsP3 and reduced amounts of minus strands. The mutants were able to assemble their nsPs at 40 degrees C into complexes that were membrane associated. Our analyses argue that P23/P123 phosphorylation is affected by macrodomain and Ala268 region sequences and in turn affects the efficient transcription of the alphavirus genome.

Amino Acid Sequence↗
PubMed2002

Engineered fetal cartilage: structural and functional analysis in vitro.

BACKGROUND/PURPOSE: This study was aimed at characterizing the structure and function of engineered fetal cartilage in vitro. METHODS: Chondrocytes from ovine specimens of fetal elastic, fetal hyaline, and adult elastic cartilage were expanded in culture and their growth rates determined. Cells were seeded onto synthetic scaffolds, which were then maintained in a bioreactor. Matrix deposition was determined by specific staining and quantitative assays for glycosaminoglycans (GAG), type II collagen (CII), and elastin, as well as compared with native tissue. Statistical analysis was by analysis of variance (ANOVA) and Students' t test, with significance set at P less than.01. RESULTS: Fetal elastic chondrocytes grew significantly faster than all other cell types. All fetal constructs resembled hyaline cartilage, regardless of the cell source. There were significantly higher levels of GAG and CII in fetal versus adult constructs, but no significant difference between fetal constructs from different sources. Unlike their adult counterparts, fetal constructs had GAG and CII levels similar to native tissues. CONCLUSIONS: Fetal chondrocytes can be rapidly expanded in culture. Compared with adult constructs, matrix deposition is enhanced in engineered fetal cartilage, which closely resembles native tissue, regardless of the cell source. Engineered fetal cartilage may be a preferable option during surgical reconstruction of select congenital anomalies.

Analysis of Variance↗
PubMed2006

Morphologic and functional analysis of sperm and testes in Aquaporin 7 knockout mice.

OBJECTIVE: To investigate the functional and morphologic role of Aquaporin 7 (AQP7) in testis and sperm. DESIGN: Experimental laboratory study. SETTING: University and research institute units. ANIMAL(S): AQP7 knockout mice (C57BL/6J background). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Morphologic analysis of testis and epididymis, daily sperm production, sperm motility, in vitro fertilization. RESULT(S): There was no difference in the morphology of the testes and epididymis between AQP7 knockout and wild-type mice. The AQP7 knockout male mice and wild-type male mice had similar numbers of offspring. Analysis of the daily sperm production and motility of AQP7 knockout mice did not show any abnormalities. Similarly, the rate of in vitro fertilization using sperm from AQP7 knockout mice was not different from wild-type mice. CONCLUSION(S): Male AQP7 knockout mice were not sterile, and their sperm did not show any morphologic and functional abnormalities.

Animals↗
PubMed1998

Functional analysis of Tpr: identification of nuclear pore complex association and nuclear localization domains and a role in mRNA export.

Tpr is a 270-kD coiled-coil protein localized to intranuclear filaments of the nuclear pore complex (NPC). The mechanism by which Tpr contributes to the structure and function of the nuclear pore is currently unknown. To gain insight into Tpr function, we expressed the full-length protein and several subdomains in mammalian cell lines and examined their effects on nuclear pore function. Through this analysis, we identified an NH2-terminal domain that was sufficient for association with the nucleoplasmic aspect of the NPC. In addition, we unexpectedly found that the acidic COOH terminus was efficiently transported into the nuclear interior, an event that was apparently mediated by a putative nuclear localization sequence. Ectopic expression of the full-length Tpr caused a dramatic accumulation of poly(A)+ RNA within the nucleus. Similar results were observed with domains that localized to the NPC and the nuclear interior. In contrast, expression of these proteins did not appear to affect nuclear import. These data are consistent with a model in which Tpr is tethered to intranuclear filaments of the NPC by its coiled coil domain leaving the acidic COOH terminus free to interact with soluble transport factors and mediate export of macromolecules from the nucleus.

Animals↗
PubMed2002

Structural and functional analysis of aldolase B mutants related to hereditary fructose intolerance.

Hereditary fructose intolerance (HFI) is a recessively inherited disorder of carbohydrate metabolism caused by impaired function of human liver aldolase (B isoform). 25 enzyme-impairing mutations have been identified in the aldolase B gene. We have studied the HFI-related mutant recombinant proteins W147R, A149P, A174D, L256P, N334K and delta6ex6 in relation to aldolase B function and structure using kinetic assays and molecular graphics analysis. We found that these mutations affect aldolase B function by decreasing substrate affinity, maximal velocity and/or enzyme stability. Finally, the functional and structural analyses of the non-natural mutant Q354E provide insight into the catalytic role of Arg(303), whose natural mutants are associated to HFI.

Arginine↗
PubMed1980

Functional analysis of vision in patients after retinal detachment repair.

A number of tests of vision were performed in patients after surgical repair of retinal detachment. The major tests performed were Snellen visual acuity, interferometric acuity, Stiles-Crawford function, and increment-threshold analysis. In two patients it was possible to evaluate all functions preoperatively. Althrough the sample it modest (ten eyes in nine patients), trends in visual recovery are identified and discussed.

Adaptation, Ocular↗
PubMed2004

Identification and functional analysis of the Drosophila gene loco.

In contrast to vertebrates, the fruit fly Drosophila melanogaster contains only a small number of regulator of G-protein signaling (RGS) domain genes. This article reviews current knowledge on these genes. Although the fruit fly is particularly amenable to genetic analysis and manipulation, not much is known about the functions and mechanisms of action. The best-studied RGS gene in Drosophila is loco, a member of the D/R12 subfamily. The four different protein isoforms all contain RGS, GoLoco, and RBD domains. This article describes the identification and functional analyses of loco in the Drosophila system and discusses some mechanistic models that may underlie loco function.

Amino Acid Sequence↗
PubMed2000

Functional analysis of the domain organization of Trypanosoma brucei RNase HI.

The structure-function relationship of Trypanosoma brucei RNase HI was investigated by evaluating the abilities of truncated forms of the enzyme to convert RNase H substrate to product. Our studies identify a 42-amino-acid noncanonical RNase HI spacer domain essential for function. We also show that the enzyme's nuclear localization domain is not required for RNase H activity but functions as an RNA binding domain which modulates the enzyme's Mn(2+)-dependent activity. These findings show that the enzyme's RNA binding/nuclear targeting and RNase H activities are organized into discrete N- and C-terminal domains with boundaries established by its spacer domain. This is the first report of the unusual structure to function relationship of a protozoal RNase H. This relationship may be conserved in other eukaryotic RNases H suggesting that criteria preserving their structure and function may be important to their roles in nucleic acid metabolism.

Amino Acid Sequence↗
PubMed1994

Synthetic oligoribonucleotides carrying site-specific modifications for RNA structure-function analysis.

Synthetic oligoribonucleotides have become increasingly valuable in studies of RNA structure and function. A range of nucleotide analogues is available which carry modifications in the base, sugar or phosphate moieties. Such analogues have been incorporated into synthetic RNA structures to eliminate or alter individual functional groups in the RNA which potentially can take part in hydrogen-bonding or other non-covalent interactions. Comparisons of the properties of the modified RNAs with unmodified RNA models allow conclusions to be drawn concerning the importance or otherwise of specific functional groups within the RNA. These methods have been applied to studies of RNA interactions with proteins, RNA catalysis and RNA structure.

Base Sequence↗
PubMed1998

Structure-function analysis of cell adhesion by neural (N-) cadherin.

To investigate the possible biological function of the lateral "strand dimer" observed in crystal structures of a D1 domain extracellular fragment from N-cadherin, we have undertaken site-directed mutagenesis studies of this molecule. Mutation of most residues important in the strand dimer interface abolish the ability of N-cadherin to mediate cell adhesion. Mutation of an analogous central residue (Trp-2) in E-cadherin also abrogates the adhesive capacity of that molecule. We also determined the crystal structure of a Ca2+-complexed two-domain fragment from N-cadherin. This structure, like its E-cadherin counterpart, does not adopt the strand dimer conformation. This suggests the possibility that classical cadherins might stably exist in both dimeric and monomeric forms. Data from several laboratories imply that lateral dimerization or clustering of cadherins may increase their adhesivity. We suggest the possibility that the strand dimer may play a role in this activation.

Animals↗
PubMed1980

Separation and functional analysis of subpopulations of T cells in the bone marrow of the mouse.

Functional capacities of T-cells precursors have been evaluated by cell culture experiments after fractionation of bone marrow cells from normal and nude mice by 1 g velocity sedimentation. The results indicate that the T-cell precursors in the bone marrow are cycling cells, that T-cell precursors in the bone marrow of nude mice have more limited potentials than those of normal mice, and that both Thy-1.2-positive and Thy-1.2-negative precursors are stimulated by T-cell activators.

Animals↗
PubMed1997

Structural and functional analysis of small arteries from young spontaneously hypertensive rats.

We studied structural and functional changes of small muscular arteries from the mesenteric vascular bed of young spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) using a new morphometric protocol involving the use of confocal microscopy and a pressurized artery system. At 3 and 4 weeks of age, systolic pressure of SHR and WKY was similar; however, significant structural changes in the mesenteric vasculature were already present in SHR. Arteries fixed under pressure in vitro from SHR had a larger medial volume and increased number of smooth muscle cell layers but similar lumen size compared with arteries from WKY in maximally relaxed conditions. Functional studies showed that SHR arteries contracted more in response to stimulation by KCl and norepinephrine, resulting in a significantly smaller lumen size in these vessels than in those from WKY. SHR arteries precontracted with KCl were also able to maintain a smaller lumen diameter than WKY arteries when challenged with increasing pressure levels. No difference in the sensitivity of response of these arteries to norepinephrine stimulation was found. At 3 and 4 weeks of age, mesenteric arteries from some SHR and WKY were not responsive to periarterial nerve stimulation, and the number of responders was higher in the WKY than SHR. However, a greater degree of contraction was found in SHR arteries responding to field stimulation at 4 weeks than in WKY arteries. We conclude that there is a temporal difference in the rate of functional maturation of the innervation in SHR arteries compared with WKY arteries. Structural changes of the small muscular arteries, caused by an increase in the medial volume, and increased number of smooth muscle cell layers are primary changes that contribute to the development of hypertension in the SHR because these changes are present at the age when blood pressure is similar in SHR and WKY.

Animals↗
PubMed2003

Functional analysis and treatment of verbal perseverations displayed by an adult with autism.

The function of perseverative speech for an adult man who had been diagnosed with autism and mental retardation was examined. Results showed that verbal perseverations were maintained by social attention. An intervention consisting of differential reinforcement of appropriate verbal responses and extinction of perseverative verbal responding was effective in decreasing verbal perseverations.

Adult↗
PubMed2003

A direct transposon insertion tool for modification and functional analysis of viral genomes.

Advances in DNA transposition technology have recently generated efficient tools for various types of functional genetic analyses. We demonstrate here the power of the bacteriophage Mu-derived in vitro DNA transposition system for modification and functional characterization of a complete bacterial virus genome. The linear double-stranded DNA genome of Escherichia coli bacteriophage PRD1 was studied by insertion mutagenesis with reporter mini-Mu transposons that were integrated in vitro into isolated genomic DNA. After introduction into bacterial cells by electroporation, recombinant transposon-containing virus clones were identified by autoradiography or visual blue-white screening employing alpha-complementation of E. coli beta-galactosidase. Additionally, a modified transposon with engineered NotI sites at both ends was used to introduce novel restriction sites into the phage genome. Analysis of the transposon integration sites in the genomes of viable recombinant phage generated a functional map, collectively indicating genes and genomic regions essential and nonessential for virus propagation. Moreover, promoterless transposons defined the direction of transcription within several insert-tolerant genomic regions. These strategies for the analysis of viral genomes are of a general nature and therefore may be applied to functional genomics studies in all prokaryotic and eukaryotic cell viruses.

Amino Acid Sequence↗