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At least 1,621 records · Page 90Linked to original sources
PubMed1991

Intraocclusal distance between the anterior teeth in intercuspal position.

We recorded intercuspal occlusal contacts using silicone for 20 subjects with complete dentition maintaining their masseter muscle contraction levels at 10 and 30% of maximum EMG activity. A computer-aided video system was used to read the silicone image and translate the intensity of transmitted light to the thickness corresponding to the distance between opposing teeth. The intraocclusal distance was greater in the anterior than in the posterior teeth. The intraocclusal distance in the canines was intermediate between that in the incisors and posterior teeth. Although these tendencies were the same at the 10 and 30% EMG levels, an increase in the EMG level decreased all the distances.

Adult↗
PubMedDate not supplied

[Determination of the distance between spin labels and the paramagnetic center in spin-labeled proteins according to parameters of the saturation curves of the label EPR spectra at 77 degrees K].

A new method of estimation of the distance between spins of the spin-label and paramagnetic center is suggested. Method is based on the quantitative analys of saturation curve of spin-label EPR spectra at 77 degrees K. New approaches have been tested using haemoglobin labeled on SH-groups with various iminoxyl radicals. Values of the distances between labels and haem estimated from the saturation curve parameters and by current methods and values of distances estimated from X-ray data are in good agreement. In the case of rapid spin relaxation of he paramagnetic center, the new method allows one to determine a farther distance. Results of the present work make it possible to investigat by the spin-label technique the structure of haem-containing propeins and the structure of other proteins with known spin relaxation time of paramagnetic center.

Chemical Phenomena↗
PubMed1991

Promoter activity and distance constraints of one versus two Sp1 binding sites.

In the simple adenovirus 2 early 1B (E1B) promoter, moving the single Sp1 transcription factor binding site (GC box) from its wild-type position eight base pairs (bp) from the TATA box to 30 bp upstream is equivalent to its deletion (Wu, L., and Berk, A. (1988) Genes & Dev. 2, 403-411). In more complex promoters, multiple upstream elements regulate transcription over greater distances. To understand these spacing constraints, we placed two GC boxes in phase at various distances from the E1B TATA box. Whereas one GC box at eight bp from TATA increases transcription in vivo 5-fold compared with TATA alone (Wu, L., Rosser, D. S. E., Schmidt, M. C., and Berk, A. (1987) Nature 326, 512-515), two GC boxes increased in vivo transcription 25-30-fold. Transcriptional stimulation by two GC boxes fell off rapidly in vivo at 30 bp from TATA, remained approximately constant through 50 bp, then decreased again at 70 bp. Consequently, two GC boxes have a multiplicative effect at eight bp from TATA and continue to stimulate transcription at a greater distance from TATA than a single Sp1 site. Quantitatively different results were observed for in vitro transcription using a nuclear extract; a more linear fall off with increasing distance from TATA was observed. Separating the two GC boxes progressively decreased transcription. E1A stimulation of these promoters in vivo indicates that Sp1 transcription control is independent of E1A transactivation.

Adenoviridae↗
PubMed1991

Distance between skeletal protein 4.1 and the erythrocyte membrane bilayer measured by resonance energy transfer.

To assess the molecular architecture of the human erythrocyte skeletal protein 4.1:bilayer interface, the distance between a donor sulfhydryl-specific fluorescent probe attached to a region near the glycophorin-binding domain of protein 4.1 and an acceptor lipophilic probe in the exposed leaflet of inside-out vesicles (IOVs) was measured by fluorescence resonance energy transfer. To prevent aggregation and loss of function, protein 4.1 was labeled in situ on the surface of IOVs, purified, and rebound onto fresh IOVs. The labeled protein 4.1 was similar to the native protein in its gel electrophoretic pattern and its binding affinity to stripped-IOVs (Kd 35 +/- 4 nM). Energy transfer was assessed using two donor-acceptor pairs, 5-[2-[(iodoacetyl)amino]ethyl] aminonaphthalene-1-sulfonic acid and 3,3'-ditetradecyloxacarbocyanine perchlorate, or 5-iodoacetamidofluorescein and tetramethylrhodamine phosphatidylethanolamine. Using both donor fluorescence intensity and lifetime quenching measurements, an average distance of 75 +/- 5 A between the probe on the protein and the surface of IOVs was found. In parallel fluorescence resonance energy transfer studies with protein 4.1 and liposomes with a phospholipid composition similar to the inner leaflet of the red cell membrane, a closer distance was found (49 +/- 5 A). Two control experiments validated energy transfer: (a) the spectrum of a mixture of IOVs separately labeled with donor and acceptor was different from the spectrum of the doubly labeled IOVs at identical donor and acceptor concentrations; and (b) no energy transfer was observed following detergent disruption of the geometric relationship between donor and acceptor. Taken together, these observations suggest that membrane-bound protein 4.1 is elongated and that the labeled site is located at a position deep in the 30-kDa N-terminal glycophorin-binding domain of the protein. The data are also consistent with the view that the cytoplasmic tail of glycophorin is interposed between protein 4.1 and the lipids. These experiments represent the first measurement of a distance between a skeletal protein and the lipid bilayer.

Cytoskeletal Proteins↗
PubMedDate not supplied

Some interrelations between blood pressure parameters and claudication distances.

Sixty males and 2 females with the mean age of 58.1 years ranging from 39 to 80 years with atherosclerotic lesions of the arteries of lower extremities were studied. The claudication distance was subdivided into two segments: the first included the distance up to the onset of pain and the second one when the patients had to stop walking because of the severity of pain. The systemic systolic pressure and the poststenotic ankle pressure over both arteries on both calves by a Doppler ultrasound apparatus were measured and the individual pressure gradients were calculated. It was demonstrated that both claudication intervals were related to the poststenotic pressure as well as to the pressure gradient. The stepwise regression analysis showed a significant relationship between both distances and the lowest value of all ankle pressure measurements over four tibial arteries. The closest correlation (R = 0.98) was recorded between the initial and final claudication distance and it persisted even after the elimination of all pressure parameters.

Blood Pressure↗
PubMed1990

Phospholipases A2: a dendrogram from a distance matrix based on size and hydrophobicity of the residues in their homologous sequences.

A distance matrix was obtained from aligned homologous sequences of 32 phospholipases A2 (EC 3.1.1.4) (24 from Elapid and 5 from Viperid venoms, and 3 from mammals), on the basis of the quantities Dij which are defined from a two-dimensional vector representation of the amino acid residues (dimensions: size and hydrophobicity). These Dij quantities were proposed in a previous paper (Ventura, M. M., (1989), An. Acad. brasil. Ci., 61: 215). A dendrogram was constructed from this distance matrix employing, for cluster analysis, the unweighted pair-group using arithmetic averages. Two groups of phospholipases A2: a) Elapid venom enzymes together with the three mammalian pancreatic enzymes (bovine, equine and porcine), and b) Viper venom enzymes (Crotalus, Trimeresurus and Bitis enzymes) can be well distinguished in the topology of the dendrogram. The Elapid group of enzymes is divided into two subgroups: a) Naja, Hemachatus and Bungarus venom enzymes, and b) Notechis, Laticauda, Enhydrina and Oxyuranus venom enzymes. It is observed that there is a close similarity between the mammalian pancreatic phospholipases A2 and the enzymes from Naja, Hemachatus and Bungarus. These results are similar to those reported by Dufton and Hider (Eur. J. Biochem., 137:545 (1983] which were obtained from the distance matrix based on minimum mutation distance between 25 selected residue positions in the pairwise compared sequences.

Animals↗
PubMed1990

Sampling strategies for distances between DNA sequences.

An international effort is now underway to obtain the DNA sequence for the entire human genome (Watson and Jordan, 1989, Genomics 5, 654-656; Barnhart, 1989, Genomics 5, 657-660). This Human Genome Initiative will generate sequence data from several species other than humans, and will result in several copies per species of at least some regions of the genome. Although the project has generated much interest, it is but one aspect of the widespread effort to generate DNA sequence data. Published sequences are collected in common databases, and release 63 of GenBank in March 1990 contained 40,127,752 bases from 33,337 reported sequences (News from GenBank 3; Mountain View, California: Intelligenetics, Inc., 1990). Large though this database is, it is only about 1% of the number of bases in the human genome. Interpretations of data of such magnitude are going to require the collaborative efforts of biometricians and molecular biologists, and an aim of this paper is to show that there is also a role for readers of this journal in the design of surveys of DNA sequences. Discussion here will center on the use of sequence data in evolutionary studies, where some region of DNA is sequenced in several different species. The object is to infer the evolutionary history of that particular region, or of the species themselves. Statistical issues in the very important studies on sequences to locate and characterize regions responsible for human diseases will not be addressed here. We will discuss appropriate ways of measuring distances between DNA sequences and of predicting the sampling properties of the distances. There are procedures for inferring evolutionary histories for a set of elements that depend on a matrix of distances between each pair of elements, and the precision of resulting trees must be influenced by the precision of the distances. We will show that account needs to be taken of two sampling processes--the sampling of sequences by the investigator ("statistical sampling"), and the sampling of genetic material involved in the formation of offspring from a parental population ("genetic sampling").

Analysis of Variance↗
PubMed1990

Measurement of skin-to-kidney distance in children: implications for quantitative renography.

Variation in skin-to-kidney center distance has been shown to have a significant influence on quantification of renal function with the gamma camera. Several techniques to compensate for this variability have been proposed in adults, yet it has been suggested that depth correction is not necessary for quantitative renography in children. Skin-to-kidney center distances were measured from computed tomograms in 53 supine pediatric patients. Nearly 40% of the kidneys examined varied more than 1 cm from the average renal depth, and 8% deviated more than 2 cm. Right kidney depth differed from left kidney depth by more than 1 cm in less than 10% of the patients. Measurements were in agreement with regression equations based on lateral scintigraphy in children, but were consistently underestimated by nomograms developed for skin-to-kidney center distance in adults. Failure to recognize interindividual variability in skin-to-kidney center distance can introduce significant errors in quantitative pediatric renography.

Body Constitution↗
PubMed1987

Ketanserin in intermittent claudication: effect on walking distance, blood pressure, and cardiovascular complications.

In a 7-center Scandinavian double-blind placebo-controlled study of 179 patients with intermittent claudication, the effect of the serotonin antagonist ketanserin was evaluated on walking distance, brachial and ankle blood pressure, and symptoms. For all centers together, pain-free walking distance was significantly increased after 6 months with both ketanserin (+65%; 71 patients) and placebo (+42%; 78 patients), with no significant difference. However, there was large variability among centers. Classification of "responders" (doubling of walking distance) and patients who deteriorated (decrease of walking distance or dropout for inefficacy) showed significantly more patients responding and significantly fewer patients deteriorating with ketanserin than with placebo. Systemic blood pressure was significantly decreased by ketanserin in hypertensive, but not normotensive, patients, while ankle pressure was unaffected. The incidence and nature of side effects were equal with ketanserin and placebo, but there were more side effects causing dropout in the ketanserin group. An unexpected and possibly important observation was the occurrence of six serious cardiovascular events (myocardial infarction, cerebrovascular complications, and development of rest pain) in the placebo group but none in ketanserin-treated patients. Moreover, there were four additional similar complications in the placebo run-in period. Ketanserin appears to be beneficial in a subgroup of patients with intermittent claudication. A fortuitous finding of this study is that ketanserin might possess a protective effect against thrombovascular complications in patients with intermittent claudication.

Adult↗
PubMed1989

Changes of walking distance in patients with intermittent claudication during six months intensive physical training.

Patients with intermittent claudication were treated with six months intensive physical training. They were instructed to walk with a speed of 6 km/h until they got complaints and then to rest for some time. This sequence was repeated until men below 65 years had walked 2 km. Men above the age of 65 years and women had to walk 1.5 km. This training session was performed 3 times a day. Every two months the claudication distances in a corridor and on a treadmill were measured. Out of 95 patients 65 completed the training. In 38 patients (59%) there was no substantial change in walking distance. Fourteen patients (22%) doubled their walking distance, seven (11%) could walk more than 1000 m, but their complaints remained. Six (9%) could walk more than 1000 m without claudication pain. Most patients gained their result during the last 2 months of the program. After the training 48% of the patients were satisfied with their walking distance.

Adult↗
PubMed1985

Distances between the functional sites of the (Ca2+ + Mg2+)-ATPase of sarcoplasmic reticulum.

Luminescence energy transfer measurements have been used to determine the distances between the two high affinity Ca2+ binding-transport sites of the (Ca2+ + Mg2+)-ATPase of skeletal muscle sarcoplasmic reticulum. The lanthanide Tb3+ situated at one high affinity Ca2+ site was used as the transfer donor, and acceptors at the other Ca2+ site were the lanthanides Nd3+, Pr3+, Ho3+, or Er3+. Terbium bound to the enzyme was excited directly with a pulsed dye laser. Analysis of the changes in the terbium luminescence lifetime due to the presence of the acceptor indicates that the distance between the Ca2+ sites is 10.7 A. The distance between the Ca2+ sites and the nucleotide-binding catalytic site was determined using Tb3+ at the Ca2+ sites and either trinitrophenyl nucleotides (TNP-N) or fluorescein 5-isothiocyanate (FITC) in the catalytic site as energy acceptors. The R0 values for the Tb-acceptor pairs are approximately 30 and approximately 40 A for TNP-N and FITC, respectively. The distance between Tb3+ at the Ca2+ sites and TNP-ATP at the nucleotide site is approximately 35 A and that between the Ca2+ sites and the FITC labeling site is approximately 47 A. Considerations of the molecular dimensions of the ATPase polypeptide indicate that while the two Ca2+ sites are close to each other, the Ca2+ sites and the nucleotide site are quite remote in the three-dimensional structure of the enzyme.

Animals↗
PubMed1988

[Medico-genetic study of the population of Kostroma Province. VI. The parameters of isolation by distance in the populations of the Bui and Shar'ya Districts of Kostroma Province].

A model of isolation by distance proposed by Malécot and developed by Morton is applied to the data on marriage distances collected in two regions of Kostroma Province. There is good agreement between the estimates of local inbreeding when using the isonymy method and the model of isolation by distance. Interpopulation kinship approaches 0 at the distance 700 km. The mean coefficient of kinship for parents in the families with autosomal-recessive pathology is 20 times higher than mean coefficient of kinship in the population.

Consanguinity↗
PubMed1988

The validity generalization of distance run tests.

The validity generalization model was used to examine the generalizability of the validity of distance run tests as measures of cardiorespiratory function. A literature search was conducted to identify studies in which distance run test scores were correlated with VO2 max scores obtained from a stress test on a treadmill. The data base was limited to runs of at least one mile or 9 min and the VO2 max scores expressed as mL.kg-1.min-1. The concurrent validity of distance run tests was not shown to be generalizable across all situations. When the data were analyzed by gender, the validity of distance run tests was more generalizable for women than for men. In the analysis of test scores for boys and girls, the validities appeared to be generalizable, although the results should be interpreted with caution owing to small samples sizes.

Adolescent↗
PubMed1988

[Interorbital distance in the skull of the newborn infant].

Authors have measured interorbital radiological distance in 45 newborns (26 males and 19 females), with a gestational age of 37.644 +/- 3.682 weeks (mean +/- SD), with a range of 25 to 42 weeks. The values obtained were 15.538 +/- 2.437 millimeters (mean +/- SD) for males and 15.894 +/- 1.943 mm (mean +/- SD) for females. The interorbital distance has a positive correlation with gestational age, weight, bizygomatic distance and minimal frontal width. Interorbital distance is closely correlated to the minimal frontal width in males.

Birth Weight↗
PubMed1986

Fluorescence studies of chicken liver fatty acid synthase. Segmental flexibility and distance measurements.

The 4'-phosphopantetheine of chicken liver fatty acid synthase was specifically labeled with the fluorescent substrate analog coenzyme A 6-[7-nitrobenz-2-oxa-1,3-diazol-4-yl]aminohexanoate at low salt concentrations. A serine at the active site of the thioesterase was specifically labeled with the fluorescent compounds 6-[7-nitrobenz-2-oxa-1,3-diazol-4-yl]aminopentylmethylphosphono fluoridate and/or pyrenebutyl methylphosphonofluoridate. Dynamic anisotropy measurements indicate the thioesterase has considerable segmental flexibility, whereas the fluorescent labeled 4'-phosphopantetheine does not display detectable local or segmental flexibility. Fluorescence resonance energy transfer measurements indicate that the distance between the fluorescent label at the end of the 4'-phosphopantetheine and NADPH bound to the beta-ketoacyl reductase or enoyl reductase site on the same polypeptide chain is essentially the same, approximately 38 A. The two types of reductases were distinguished by specifically blocking enoyl reductase with pyridoxal 5'-phosphate. No significant energy transfer occurs between sites on different polypeptide chains so that the distances must be greater than 55 A. The distance between the serine on the thioesterase and the 4'-phosphopantetheine on the same polypeptide is 48 A; again no interpolypeptide chain energy transfer was observed. The distance between the serines of the two thioesterases within a fatty acid synthase molecule is greater than 56 A. The monomeric enzyme obtained at 1 degree C does not have beta-ketoacyl synthase and reductase activities. Also fluorescent titrations indicate NADPH is not bound to beta-ketoacyl reductase in monomeric enzyme. The addition of potassium phosphate to the monomers at 1 degree C rapidly dimerizes the enzyme and restores the beta-ketoacyl reductase activity. The beta-ketoacyl synthase activity is slowly restored when the dimer is raised to room temperature. The results obtained suggest that relatively large conformational changes may be part of the catalytic cycle.

3-Oxoacyl-(Acyl-Carrier-Protein) Reductase↗
PubMed1987

The effects of distance and season on the use of boreholes in northeastern Imo State, Nigeria.

A study was conducted in a rural area of northeastern Imo State to examine the effect of distance and season on the use of boreholes, provided at a borehole-to-population ratio of 1 to 440. The type of water source used by households varied according to season. In the water-scarce dry season, 98% of households used borehole water: 64% as their sole source, a further 26% as their main source, and 8% as a secondary source. The use of borehole water as the main source was little influenced by distance until the household-to-borehole distance reached approximately 2 km. The situation was different in the wet season when the availability of water sources was much greater. In this season, rainwater was the main water source for 64% of households. Borehole water was the main source for only 31% of households. In the rainy season, the use of borehole water as the main source showed a significant decrease with increasing household-to-borehole distance. The provision of one borehole for 400-500 people was associated with a high rate of use as the main water source only in the dry season. However, the use of boreholes as either a main or alternative source was high in both seasons and it is possible that those households that used boreholes as an alternative source used the water for drinking.(ABSTRACT TRUNCATED AT 250 WORDS)

Health Promotion↗
PubMed1985

Relationships among three Muslim and one Hindu endogamous groups of Madhya Pradesh. I. Genetic distance analysis.

Genetic distances have been estimated among three Muslim groups, the Sunni, Shia and the Bohra, and a Hindu group, the Brahman, from five districts of the centrally located state of Madhya Pradesh in India. The distances are based on five genetic systems, the ABO, MN and Rh blood groups. PIC taste sensitivity and colour blindness. None of the 6 distances among the 4 groups was statistically significant. However, cluster analysis showed that Sunni and Shia form a very close cluster which is successively joined by Brahman and Bohra, the latter having comparatively large distances from all the other groups.

Alleles↗
PubMedDate not supplied

[Estimation of the distance between the iron-sulfur cluster of Fe-protein and the nearest iron-sulfur cluster of Mo-Fe-protein of nitrogenase on the basis of the inductive-resonance theory of energy transfer].

The distance between fluorescein mercuric acetate (FMA), attached to the HS-group of Fe- and Mo-Fe-protein, and the nearest iron-sulphur cluster (ISC) was determined. For Fe-protein the distance was 18--20 A and for Mo-Fe-protein 12--14 A. The distance between Fe-protein FMA and the nearest Mo-protein ISC determined by complementation of the labelled Fe-protein and native Mo-Fe-protein was 14--16 A. The distance between MO-OFe-protein ISC and complement Fe-protein ISC was 18--20 A. A te-protein ISC permitted to suppose that the electron was transfered from Fe-protein ISC to Mo-Fe-protein ISC by the contact of the ISC or with the help of ATP molecule.

Binding Sites↗