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At least 73 records · Page 4Linked to original sources
PubMed1996

Segment inertial parameter evaluation in two anthropometric models by application of a dynamic linked segment model.

The estimation of segment inertial parameters (SIPs) is an important source of error in inverse dynamic analysis. In most individual cases SIPs are derived from extrapolation of known SIPs of a certain population through regression equations (proportional models). Another well-known method is the use of mathematical approximation of the shape of human body segments combined with estimations of segment densities (geometric models). In the current study five males and five females performed four different lifting movements in the sagittal plane. A full body linked segment model was applied twice to the same data set, once using a proportional and once using a geometric anthropometric model. As a full body linked segment model is an overdetermined system of equations, four equations could be formed to test the summed effect of SIP errors on the inverse dynamic analysis. The overall performance in terms of coefficients of correlation was better for the geometric model as compared to the proportional model. When a back lifting movement was performed, the equations indicated systematic errors in the proportional model. However, when a leg lifting movement was performed, the equations indicated systematic errors in the geometric model. Therefore, analyzing only one kind of movement does not suffice to draw conclusions with respect to the reliability of an anthropometric model.

Adolescent↗
PubMedDate not supplied

Non-random selection of gene segment 3 and random selection of gene segment 5 observed in reassortants generated in vitro between rotavirus SA11 and RRV.

A total of 154 clones of reassortants between rotavirus RRV and SA11 were isolated in vitro in order to compare the selection modes of each RNA segment in reassortant formation with those in the in vivo experiment (carried out by Gombold and Ramig) using the same parent strains in which the occurrence of non-random selection of gene segments 3 and 5 was observed. In reassortants isolated from a cross RRV x SA11-L2 (66 isolates) and a cross RRV x SA11-S1 (88 isolates), 36 and 57 different genotypes were identified, respectively. Segregation rates of SA11 RNA segments 1, 5, 8, 9 and 11 were significantly different as compared with those previously reported in the in vivo experiment. While RNA segment 3 was preferentially selected from an SA11 parent, the segregation rate of SA11 gene 5 was relatively low in vitro. Thus, the selection mode of rotavirus RNA segments was found to be different between in vivo and in vitro reassortments.

Animals↗
PubMed1993

Motility differences between long-segment and short-segment Barrett's esophagus.

Barrett's esophagus has been described as a motility disorder of the esophagus, but the issue of whether or not the disorder precedes the columnar lining has been debated. Motility records of 70 patients with histologically proven Barrett's esophagus were analyzed. A comparison of the swallow responses was made between those patients who had a limited Barrett's segment (3 to 5 cm, n = 28) as opposed to those patients who had an extensive Barrett's segment (greater than 5 cm, n = 42). Patients with an extensive segment had a significantly lower amplitude (p < 0.01) of esophageal contraction and a significantly longer duration (p < 0.01) of contraction compared with patients with a limited segment. These differences were most marked in the distal esophageal segments. There was a progressive deterioration of esophageal motility with advanced disease.

Adult↗
PubMed1986

Reinnervation of teeth after segmental osteotomy in the cat. The effect of segment repositioning and bone grafting.

The reinnervation of teeth after segmental osteotomy has been investigated using electrophysiological techniques in 6 cats. An osteotomy which divided the entire mandible was carried out bilaterally. The anterior segment was repositioned anteriorly by 5 mm and in 3 animals bone grafts were inserted at the osteotomy sites. A jaw opening reflex could be evoked by stimulation of 9 of the 12 denervated canine teeth by 9 weeks after the osteotomy. 12 weeks after the operation, recordings were made from the denervated teeth, the inferior alveolar nerve central to the osteotomy, and from nerves supplying adjacent tissues. The results were compared with those of previous experiments in which the anterior segment was not repositioned. Regenerating inferior alveolar nerve fibres re-innervated 18 of the 24 teeth denervated by osteotomy without bone grafting and 21 of the 24 teeth denervated by osteotomy with bone grafting. These fibres were few in number and had decreased conduction velocities. Pulpal fibres were also present in the ipsilateral mental and lingual nerves and the contralateral inferior alveolar, mental and lingual nerves. There was very little difference in the reinnervation of the teeth after osteotomy without repositioning the segment, after repositioning the segment without bone grafting or after repositioning with bone grafting.

Animals↗
PubMed1978

Amino acid sequences of alpha-helical segments from S-carbosymethylkerateine-A. Complete sequence of a type-I segment.

The amino acid sequence of a type-I helical segment from the low-sulphur protein (S-carboxymethylkerateine-A) of wool was determined by combining automatic and manual-sequencing data. Whereas in the type-II helical segment most of the cationic groups occur in pairs, 11 of the 22 anionic residues in the sequence of the type-I segment were situated next to a second anionic residue. This suggests possible interactions between type-I and type-II helical segments in alpha-keratin. As observed with the sequence of a type-II helical segment a model constructed on 3.6 residues per turn of helix shows a line of hydrophobic residues along the helix, thereby supporting the physicochemical evidence that the molecule is predominantly helical and forms part of a coiled-coil structure. Examination of the sequence data by predictive methods indicates the possibilty of extensive sections of alpha-helix interspersed with discontinuities. The molecule contains a number of regions with peptide sequences identical with those found by other workers after enzymic digestion of fractions from oxidized wool.

Amides↗
PubMed1991

Ambisense segment 3 of rice stripe virus: the first instance of a virus containing two ambisense segments.

The complete nucleotide sequence of rice stripe virus (RSV) segment 3 shows that it has two open reading frames, one in the viral-complementary sequence, which codes for the nucleocapsid protein, and the other in the viral-sense sequence. The non-coding region between the ambisense genes in RSV segment 3 contains several U and A tracts, as do the ambisense S segments of phleboviruses and uukuviruses. As we have previously shown that RSV segment 4 has an ambisense nature, this is the first instance of a virus containing two ambisense segments.

Amino Acid Sequence↗
PubMed1993

Segment durations and accent as cues to word segmentation in Dutch.

This paper investigates the relative contributions of accentuation and of durational word boundary cues to listeners' perceived word segmentation in Dutch. A listening experiment is reported, in which 36 two-word phrases with an ambiguous word boundary were used as stimuli. Four groups of 20 subjects each had to make a forced binary choice between the two contrastive boundary positions. Accent position on either the first or second word was varied between stimulus phrases. In both contrastive realizations of each ambiguous phrase, two durational boundary cues were manipulated, viz. duration of the pivotal consonant and rise time of the postboundary vowel. Results show that durational word boundary markers are perceptually relevant for subjects' perceived word segmentation, but only if the manipulated segment is realized as word-initial. Second, accuracy in perceived word segmentation is higher if the second word (following the ambiguous boundary position) is accented. The latter result is probably due to the higher acoustic and perceptual salience of durational as well as spectral boundary cues, which occur in initial position in the second word. Hence, the contribution of accent to word segmentation may be partly due to its "enhancing" effect on phonetic word boundary markers.

Humans↗
PubMed1991

Interactions between fused, a segment-polarity gene in Drosophila, and other segmentation genes.

Fused (fu) is a segment polarity gene whose product is maternally required in the posterior part of each segment. To define further the role of fused and determine how it interacts with other segmentation genes, we examined the phenotypes obtained by combining fused with mutations of pair rule, homeotic and other segment polarity loci. When it was possible, we also looked at the distribution of corresponding proteins in fused mutant embryos. We observed that fused-naked (fu;nkd) double mutant embryos display a phenotypic suppression of simple mutant phenotypes: both naked cuticle and denticle belts, which would normally have been deleted by one of the two mutants alone, were restored. In fused mutant embryos, engrailed (en) and wingless (wg) expression was normal until germ band extension, but partially and completely disappeared respectively during germ band retraction. In the fu;nkd double mutant embryo, en was expressed as in nkd mutant at germ band extension, but later this expression was restricted and became normal at germ band retraction. On the contrary, wg expression disappeared as in fu simple mutant embryos. We conclude that the requirements for fused, naked and wingless activities for normal segmental patterning are not absolute, and propose mechanisms by which these genes interact to specify anterior and posterior cell fates.

Animals↗
PubMed1991

Chemical synthesis of human beta-endorphin(1-27) analogs by peptide segment coupling. Leucine and glycine residues bearing thiocarboxyl functions as junctions for peptide segment coupling.

[Gly8]beta hEP(1-27)NH2 and [L-Leu8]beta hEP(1-27)NH2, two analogs of human beta-endorphin, were synthesized by both all-stepwise solid phase synthesis and peptide segment coupling. For the peptide segment coupling method, two thiocarboxyl peptides. Msc-[Gly8]beta hEP(1-8)SH and Msc-[L-Leu8]beta hEP(1-8)SH, were synthesized by standard solid phase method on 4-[alpha-(Boc-Gly-S)benzyl]phenoxyacetamidomethy-resin and 4-[alpha-(Boc-L-Leu-S)benzyl]phenoxyacetamidomethy-resin. These two thiocarboxyl peptides were coupled to H-[Lys(Cit)9,19,24]-beta hEP(9-27)NH2. [Gly8]beta hEP(1-27)NH2 and [L-Leu8]beta hEP(1-27)NH2 were obtained after removal of Msc groups and citraconyl groups from products of the segment coupling reaction. The yields of both [Gly8]beta hEP(1-27)NH2 and [L-Leu8]beta hEP(1-27)NH2 in the segment coupling reaction were approximately 18%. Less than 1% of racemization of Leu-8 occurred during coupling of Msc-[L-Leu8]beta hEP(1-8)SH to H-[Lys(Cit)9,19,24]-beta hEP(9-27)NH2. Results of amino acid composition analysis, analysis by reverse phase high pressure liquid chromatography and receptor binding activity assays of the analogs showed that peptide analogs prepared by segment coupling method and those prepared by all-stepwise solid phase synthesis were identical. Results of receptor binding activity assays suggested that the molecular charge properties of beta-endorphin(1-27) and its analogs influenced the receptor binding activity.

Amino Acid Sequence↗
PubMed1995

Interposition of 'wide' cycloperistaltic segments into isolated segments of jejunum--influence on fluid perfusion.

Two isolated jejunal segments (Thiry-Vella (T-V) loops) were created in 7 dogs. One contained a 'wide' cycloperistaltic (C-P) segment while the other, acting as a control, did not. The C-P segment had the same diameter as the jejunum. Fluid perfusion experiments showed that there were no changes in the volume of output, absorption and pooling of the fluid in the T-V loops containing the 'wide' C-P segment. This was in contrast with significant changes shown in earlier experiments using 'narrow' C-P segments.

Animals↗
PubMed1991

Effect of soft segment chemistry on the biostability of segmented polyurethanes. I. In vitro oxidation.

A series of segmented polyurethanes (SPUs) containing various polyol soft segments was prepared and their resistance to oxidative degradation was investigated after aging in AgNO3 solution. The SPU with the polyether soft segment showed a large reduction in mechanical strength after exposure to the oxidative environment. Surface cracking was often observed for these specimens. XPS measurements revealed that scission of the ether linkage occurs upon oxidation. The oxidative resistance of SPUs containing aliphatic hydrocarbon soft segments was significantly improved over the poly(tetramethylene oxide) (PTMO) based polyurethane.

Calorimetry, Differential Scanning↗
PubMed1988

Ultrastructure of the kidney of a South American caecilian, Typhlonectes compressicaudus (Amphibia, Gymnophiona). I. Renal corpuscle, neck segment, proximal tubule and intermediate segment.

The ultrastructure of the renal corpuscle, the neck segment, the proximal tubule and the intermediate segment of the kidney of a South American caecilian, Typhlonectes compressicaudus (Amphibia, Gymnophiona) was examined by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and freeze-fracture technique. The glomerular filter apparatus consists of the podocyte epithelium, a distinct basement membrane, a subendothelial space and the capillary endothelium. Emanating from the podocyte cell body, several long primary processes encircle neighboring capillaries. The short slender foot processes originating from the primary processes interdigitate with those from other primary processes, thereby forming the meandering filtration slit. Thick bundles of microfilaments are found in the primary processes, but absent in the foot processes. The basement membrane consists of a lamina rara externa and a rather thin lamina densa (50 nm thickness). The wide subendothelial space contains abundant microfibrils, a few collagen fibrils and many thin processes of mesangial cells. The endothelium is flat and fenestrated (compared to mammals displaying relatively few fenestrations); some of the fenestrations are bridged by a diaphragm. The glomerular mesangium is made up of the mesangial cells and a prominent mesangial matrix containing microfibrils and collagen fibrils. The cells of the neck and intermediate segments display numerous cilia with their microtubules arranged in the typical 9 + 2 pattern. The basal bodies of the cilia are attached to thick filaments with a clear crossbanding pattern of 65 nm periodicity. The proximal tubule is composed of cells typical for this segment (PT cells) and light cells lacking a brush border (bald-headed cells). The PT cells measure 10-25 micron in height and 15-30 micron in width and do not interdigitate at their lateral borders with each other. Their basolateral cell membrane is amplified by many folds projecting into lateral intercellular spaces and into basal recesses. The brush border is scarce and composed of loosely arranged short microvilli.

Amphibians↗
PubMed1995

Spurious ST segment depression by automated ST segment analysis.

Perioperative myocardial ischemia has been shown to be predictive of adverse cardiac outcome [1]. One method of detecting intraoperative myocardial ischemia is automated ST segment monitoring [2]. The rationale behind automated ST monitoring is that the clinician will be promptly alerted to ischemic changes in the ECG. This may lead to earlier intervention and, perhaps, improved outcome [3]. We describe a case in which automated ST segment monitoring falsely signaled the presence of intraoperative ST segment depression. This event emphasizes the importance of confirming the validity of ST segment changes before instituting therapy.

Aged↗
PubMed1982

Evaluation of normal variations in S-T segment patterns by body surface isopotential mapping: S-T segment elevation in absence of heart disease.

S-T segment elevation is commonly observed in the electrocardiogram of normal persons. To study the possible origins of such patterns, 45 normal volunteers were examined. Electrocardiographic potentials were registered from 150 torso electrodes and processed to construct isopotential maps at 2 ms intervals throughout the QRS-T interval. The maximal potentials recorded from any of the 150 electrodes were 198 +/- 76.4 and 272.1 +/- 84.2 microV at instants 40 and 80 ms into the S-T segment, respectively. Maximal voltages recorded by the six standard precordial V leads at these respective time points were 109.7 +/- 57.0 and 163.6 +/- 66.9 microV. Torso maximal potentials were significantly stronger than were those sensed by V leads; the two were significantly correlated but predictability was limited. The duration of overlap between the onset of ventricular recovery and the end of the excitation was determined from isopotential maps and ranged rom 4 to 16 ms. There was no significant correlation (p greater than 0.05) between these values and either torso or V lead potentials at either 40 or 80 ms into S-T segment. These data suggest that (1) standard precordial leads do not accurately predict maximal torso potentials during the S-T segment, and (2) the degree of overlap between repolarization and depolarization is not a major determinant of precordial voltage. Hence, the rationale for use of the term "early repolarization" to describe this clinical condition is not substantiated.

Adolescent↗
PubMed1985

Visual conspicuity of a moving dot, horizontal line segment or vertical line segment.

The effect of varying the retinal eccentricity of a moving target on its conspicuity were explored for targets whose shape, orientation, size and luminance were the same as the stationary background elements. The target was a dot, horizontal line segment, or vertical line segment. The main results were: (1) conspicuity increased monotically as a function of velocity for all of the cases. (2) The rate of the increase of conspicuity slowed down at around a velocity between 0.6 and 0.8 deg/sec (break in slope). (3) For individual subjects, the size of conspicuity area for a dot was not so different from that for a horizontal line segment, but it was very different from that for a vertical line segment. (4) The position of the break in slope shifted upward or downward from one another but not laterally. The results indicate that the conspicuity was not due to the sum of the outputs in movingness analyzing system (MAS, Transient-channel) and displacement analyzing system (DAS, Sustained-channel), but due to one of them according to velocity of the moving element.

Fixation, Ocular↗
PubMed1993

Putative full-length clones of the genomic DNA segments of subterranean clover stunt virus and identification of the segment coding for the viral coat protein.

Subterranean clover stunt disease is an economically important aphid-borne virus disease affecting certain pasture and grain legumes in Australia. The virus associated with the disease, subterranean clover stunt virus (SCSV), was previously found to be representative of a new type of single-stranded DNA virus. Analysis of the virion DNA and restriction mapping of double-stranded cDNA synthesized from virion DNA suggested that SCSV has a segmented genome composed of 3 or 4 different species of circular ssDNA each of about 850-880 nucleotides. To further investigate the complexity of the SCSV genome, we have isolated the replicative form DNA from infected pea and from it prepared putative full-length clones representing the SCSV genome segments. Analysis of these clones by restriction mapping indicated that clones representing at least 4 distinct genomic segments were obtained. This method is thus suitable for generating an extensive genomic library of novel ssDNA viruses containing multiple genome segments such as SCSV and banana bunchy top virus. The N-terminal amino acid sequence and amino acid composition of the coat protein of SCSV were determined. Comparison of the amino acid sequence with partial DNA sequence data, and the distinctly different restriction maps obtained for the full-length clones suggested that only one of these clones contained the coat protein gene. The results confirmed that SCSV has a functionally divided genome composed of several distinct ssDNA circles each of about 1 kb.

Amino Acid Sequence↗
PubMed1996

Multiple DNA and protein sequence alignment based on segment-to-segment comparison.

In this paper, a new way to think about, and to construct, pairwise as well as multiple alignments of DNA and protein sequences is proposed. Rather than forcing alignments to either align single residues or to introduce gaps by defining an alignment as a path running right from the source up to the sink in the associated dot-matrix diagram, we propose to consider alignments as consistent equivalence relations defined on the set of all positions occurring in all sequences under consideration. We also propose constructing alignments from whole segments exhibiting highly significant overall similarity rather than by aligning individual residues. Consequently, we present an alignment algorithm that (i) is based on segment-to-segment comparison instead of the commonly used residue-to-residue comparison and which (ii) avoids the well-known difficulties concerning the choice of appropriate gap penalties: gaps are not treated explicity, but remain as those parts of the sequences that do not belong to any of the aligned segments. Finally, we discuss the application of our algorithm to two test examples and compare it with commonly used alignment methods. As a first example, we aligned a set of 11 DNA sequences coding for functional helix-loop-helix proteins. Though the sequences show only low overall similarity, our program correctly aligned all of the 11 functional sites, which was a unique result among the methods tested. As a by-product, the reading frames of the sequences were identified. Next, we aligned a set of ribonuclease H proteins and compared our results with alignments produced by other programs as reported by McClure et al. [McClure, M. A., Vasi, T. K. & Fitch, W. M. (1994) Mol. Biol. Evol. 11, 571-592]. Our program was one of the best scoring programs. However, in contrast to other methods, our protein alignments are independent of user-defined parameters.

Algorithms↗
PubMed1996

Neutrophil nuclear segmentation in mild cobalamin deficiency: relation to metabolic tests of cobalamin status and observations on ethnic differences in neutrophil segmentation.

Neutrophil hypersegmentation is considered the most sensitive peripheral blood cell marker of cobalamin deficiency. However, its diagnostic value in the mild deficiency states that accompany most low cobalamin levels and its relation to metabolic test of cobalamin status are unknown. The authors compared neutrophil lobe averages and percent neutrophils with 5 or more lobes (%5+ lobes) in 169 subjects with their mean corpuscular volume (MCV) and serum cobalamin, methylmalonic acid (MMA), homocysteine, and folate levels and, in 65 cases, with the deoxyuridine suppression test (dUST). Only 9 subjects had hypersegmentation by lobe average and 20 subjects by %5+ lobes. They were not more often cobalamin-deficient than subjects without hypersegmentation. Moreover, only one of 34 subjects with dUST results diagnostic for cobalamin deficiency had neutrophil hypersegmentation. Both indices of neutrophil segmentation in the 169 subjects correlated significantly with homocysteine levels. They also showed weak inverse correlation with cobalamin levels, but did not correlate with MMA, folate, or MCV values. Cobalamin therapy for 6 months did not significantly change neutrophil lobe averages in 35 subjects with mild deficiency, compared with 8 nondeficient controls, and only marginally improved the %5+ lobes. A surprising, incidental observation was that blacks had significantly greater neutrophil segmentation by both criteria than did whites and others. This difference was unrelated to cobalamin or folate status. Our results indicate that dUST abnormalities precede all morphologic changes of deficiency, including hypersegmentation. Although a tendency exists for neutrophil segmentation to increase very slightly as some serum values, especially homocysteine, start to worsen in mild cobalamin deficiency, the metabolic changes precede overt hypersegmentation. Neutrophil nuclear segmentation is insufficiently sensitive in relation to metabolic evidence of deficiency to be used as a clinical tool in the diagnosis of mild cobalamin deficiency.

Asian People↗