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At least 811 records · Page 45Linked to original sources

PubMed1989

Blood clotting factor IX BM Nagoya. Substitution of arginine 180 by tryptophan and its activation by alpha-chymotrypsin and rat mast cell chymase.

Factor IX BM Nagoya (IX Nagoya) is a natural mutant of factor IX responsible for severe hemophilia B. A patient with this mutant is characterized by a markedly prolonged ox brain prothrombin time. IX Nagoya was purified from the patient's plasma by immunoaffinity chromatography with an anti-factor IX monoclonal antibody column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that treatment of IX Nagoya with factor XIa/Ca2+ resulted in cleavage only at the Arg145-Ala146 bond. Reversed-phase high performance liquid chromatography of a trypsin digest of IX Nagoya showed an aberrant peptide, which was further digested with proteinase Asp-N. Primary structure analysis of one of the Asp-N peptides revealed that Arg180 is replaced by Trp. An essentially complete (99%) amino acid sequence of IX Nagoya was obtained by sequencing fragments derived from a lysyl endopeptidase digest in which no other substitutions in the catalytic triad or substrate binding site were found. We also found that IX Nagoya is activated by alpha-chymotrypsin or rat mast cell chymase by monitoring the rate of factor X activation using a fluorogenic peptide substrate in the presence of factor VIII, phospholipids, and Ca2+. These results indicate that the substitution of Arg180 by Trp impairs the cleavage by factor XIa required for activation of this zymogen and that the substitution causes hemophilia BM.

Amino Acid Sequence↗

PubMed1985

Conformational studies of two histamine H2-receptor antagonistic phenylformamidines: mifentidine and its guanidinothiazole analogue DA 4643.

Two histamine H2-receptor antagonists of the phenylformamidine type, mifentidine (N-isopropyl-N'-(4-1H-imidazol-4-yl-phenyl) formamidine dihydrochloride; I) and DA 4643 (N-methyl-N'-(3-(2-guanidinothiazol-4-yl)-phenyl) formamidine dihydrochloride; II), have been investigated by experimental physico-chemical studies and theoretical conformational analysis. PKa determinations on the two molecules I and II show that these substances exist at physiological pH (7.4) predominantly as their monoprotonated forms at the formamidine moiety. Semiempirical quantum mechanical (MNDO, CNDO/2) and molecular mechanics (MMPI) calculations show a preference of the nearly planar conformations for I and of different low energy rotamers for II. The energy of these conformers is a function of two important torsion angles, one around the bond joining the imidazole, or the guanidinothiazole, and the phenyl ring and the other around the bond joining the phenyl ring and the formamidinium cation. When the distances between crucial parts present in I and II are considered, it results that the relatively higher flexibility of II allows accommodation of amidine pairs present in the latter at a distance similar to that found for correspondent pairs in the conformationally more restricted I. Conformational aspects of I and II are discussed with reference to a recently described conformation of cimetidine determined by X-ray method. A hypothesis of binding of H2-receptor antagonists of the phenylformamidine type is advanced with reference to electrostatic potential maps calculated for crucial part structures of I, II and cimetidine. The present work supports the hypothesis that both mifentidine and DA 4643 interact with the histamine H2-receptor at the same site, utilizing in the binding process the same, or closely similar, receptor structural features.

Chemical Phenomena↗

PubMed1985

Multidirectional tomography in otospongiosis.

Eight clinical situations are best examined by polytomography, namely, ossicular chain disruption, malleus fixation, assessing the extent of footplate fixation, delineating cochlear otospongiosis, postoperative studies of unsuccessful cases, developing an anatomic map preoperatively with particular reference to the intratympanic course of the facial nerve, ruling in or out the rare closure of the round window by otospongiosis, and differentiation of the congenital footplate fixation from true otospongiosis. We discuss each of these situations briefly.

Cochlea↗

PubMed1983

The architecture of the animal fatty acid synthetase. I. Proteolytic dissection and peptide mapping.

The vertebrate fatty acid synthetase complex consists of two, apparently identical, subunits which contain seven catalytic centers and an acyl carrier site. As a prelude to studying the functional organization of this system, a comprehensive proteolytic analysis of the chicken fatty acid synthetase subunit has been carried out. Of 24 proteases tested, seven (chymotrypsin, elastase, trypsin, Myxobacter protease, subtilisins A and B, and kallikrein) were found to be capable of inflicting specific cleavages in the native enzyme. The proteolytic profiles were analyzed with respect to both the kinetics and the size of the fragments generated. The relationships between the various fragments were further delineated by combinatorial digestions. All of the data points to the fact that the subunits are indeed identical. The cleavage patterns indicate that the fatty acid synthetase subunit is primarily arranged into three major domains of Mr 127,000, 107,000, and 33,000, since these fragments are commonly produced by most of the proteases. The latter peptides may be further subdivided and mapped by the action of individual enzymes into a number of distinct regions: the 127,000 domain into fragments of Mr 60,000, 45,000, and 23,000; the 107,000 domain into fragments of Mr 14,000, 56,000, 21,000, and 15,000; all aligned accordingly. This proteolytic map serves as a reference for the controlled dissection of the fatty acid synthetase complex, thereby allowing determination of the location of functional centers within the parent polypeptide.

Animals↗

PubMed1995

[Establishment of signal-averaged electrocardiographic system and system specific criteria].

Signal-averaging of high resolution electrocardiographic data to identify ventricular late potentials, associated with ventricular tachycardia, has emerged as a useful technique for risk stratification following myocardial infarction. Multiple lead system, filters and criteria have been used in clinical trials. As variations in data analysis are introduced, it is important to assess the impact of the final results and to ensure that criteria for normalcy, appropriate for these variation, are developed if needed. This study compares the results produced by four systems and one system with a different filter used for determination of late potential parameters in the time domain. It is concluded that varying technique and filters significant changes in the values used to identify late potentials on high-resolution electrocardiographic records. These change may have clinical impact. When using this technique in a clinical situation, parameters values, appropriate for the device, and its components should be developed, if needed.

Arrhythmias, Cardiac↗

PubMed1994

Genetic and stress-mediated influence on Aujeszky's disease virus induced interferon-alpha production in porcine leukocytes.

The ability to produce interferon-alpha (IFN-alpha) in vitro was measured in blood from 200 F2-crosses between European wild boar and Swedish Yorkshire pigs, originating from a reference pedigree for gene mapping. A total of 200 pigs of 44 litters, descendent from 4 boars and 22 sows, were stressed by transportation together with non-littermates for 5 h. Blood samples were collected from each individual twice, i.e. immediately before transportation and the day after transportation. IFN-alpha production was induced in whole blood cultures by a monolayer of fixed, Aujeszky's disease virus infected, porcine kidney cells. In general, the amount of IFN-alpha produced was significantly lower (p = 0.02) the day after transportation, although the ability to produce IFN-alpha showed a large individual variation (p < 0.001). However, both the levels of IFN-alpha produced and the decrease after transportation varied between the four parental offspring groups. Also, indications of single genes with significant effects on the ability to produce IFN-alpha were found. These results confirm a genetic influence on the ability to produce IFN-alpha. In addition, stress, such as transportation and mixing, may decrease the level of IFN-alpha produced.

Animals↗

PubMed1994

Ambiguity resolution while mapping free text to the UMLS Metathesaurus.

We propose a method for resolving ambiguities encountered when mapping free text to the UMLS Metathesaurus. Much of the research in medical informatics involves the manipulation of free text. The Metathesaurus contains extensive information which supports solutions to problems encountered while processing such text. After discussing the process of mapping free text to the Metathesaurus and describing the ambiguities which are often the result of such mapping, we provide examples of rules designed to eliminate mapping ambiguities. These rules refer to the context in which the ambiguity occurs and crucially depend on semantic types obtained from the Metathesaurus. We have conducted a preliminary test of the methodology and the results obtained indicate that the rules successfully resolve ambiguity around 80% of the time.

Abstracting and Indexing↗

PubMed1993

A fluorescence in situ hybridization map of human chromosome 21 consisting of 30 genetic and physical markers on the chromosome: localization of 137 additional YAC and cosmid clones with respect to this map.

A fluorescence in situ hybridization (FISH) map of human chromosome 21 was compiled using yeast artificial chromosome (YAC) DNA probes that encode 28 markers physically and/or genetically mapped on the chromosome. Probes that recognize the centromere and rDNA repeat sequences in the p arm were also placed as reference markers on the FISH map. For each probe, the location of the fluorescence hybridization signal was measured on metaphase chromosomes with respect to fractional chromosome length (FL) from p-ter. The location of the markers was established with a standard error of +/- 1.9 Mb using from 9 to 63 FL measurements for each probe. The relative order and separation of the markers as determined by FISH are shown to correspond well to those of other maps of the chromosome. Fifty-one additional YAC and 86 cosmid clones were also localized by FISH with respect to the 30 markers on the chromosome. The cosmids, chosen at random from a flow-sorter chromosome 21 cosmid library, show some biases in chromosome distribution.

Chromosome Mapping↗

PubMed1971

Localization of a portion of the ribosomal RNA genes in Escherichia coli.

About one-half of the genes coding for ribosomal RNA in Escherichia coli have been localized by the use of F-merogenotes. These cistrons have been positioned between 74 and 77 min on the E. coli map described by Taylor and Trotter. The episomal DNA carrying these genes was enriched by chromatography. The map position is discussed with reference to previous localization attempts.

Centrifugation, Density Gradient↗

PubMed2002

Supervisor tolerance-responsiveness to substance abuse and workplace prevention training: use of a cognitive mapping tool.

Supervisor tolerance-responsiveness, referring to the attitudes and behaviors associated with either ignoring or taking proactive steps with troubled employees, was investigated in two studies. The studies were conducted to help examine, understand and improve supervisor responsiveness to employee substance abuse. Study 1 examined supervisor response to and tolerance of coworker substance use and ways of interfacing with the Employee Assistance Program (EAP) in two workplaces (n = 244 and 107). These surveys suggested that engaging supervisors in a dialogue about tolerance might improve their willingness to use the EAP. Study 2 was a randomized control field experiment that assessed a team-oriented training. This training adopted a cognitive mapping technique to help improve supervisor responsiveness. Supervisors receiving this training (n = 29) were more likely to improve on several dimensions of responsiveness (e.g. likely to contact the EAP) than were supervisors who received a more didactic, informational training (n = 23) or a no-training control group (n = 17). Trained supervisors also showed increases in their own help-seeking behavior. Procedures and maps from the mapping activity (two-stage conversational mapping) are described. Overall, results indicate that while supervisor tolerance of coworker substance use inhibits EAP utilization, it may be possible to address this tolerance using team-oriented prevention training in the work-site.

Adult↗

PubMed2001

Dispersion of atrial repolarization in patients with paroxysmal atrial fibrillation.

UNLABELLED: To study the role of the dispersion of atrial repolarization (DAR) in the genesis of atrial fibrillation (AF), monophasic action potentials (MAP) were recorded simultaneously from a catheter at the high lateral right atrium (HLRA) and a catheter moving around the high, middle and low lateral right atrium (RA) the high, anterior and posterior septal RA and the RA appendage in 15 patients with paroxysmal AF and 15 patients with atrioventricular nodal re-entry tachycardia (AVNRT) or concealed Wolff-Parkinson-White syndrome (WPW) without history of AF. After recordings during sinus rhythm (SR), MAPs were recorded during programmed stimulation (PS) via the HLRA catheter at a drive cycle length (CL) of 500 ms. Thus, MAPs were recorded simultaneously from 2 sites at a time and sequentially from 4 to 12 sites during SR, drive pacing and PS. Taking the MAP at the HLRA as reference, the dispersion of repolarization time (dispersion of RT) and its two components, the dispersions of activation time (dispersion of AT) and MAP duration (dispersion of MAP duration) among the 4 to 12 sites were calculated and taken as parameters of DAR. RESULTS: During SR and PS, the maximal dispersion of RT was significantly greater in AF than in control patients, 113+/-49 ms vs 50+/-28 ms (P<0.001) and 114+/-56 vs 70+/-43 ms (P<0.05) respectively. The increased dispersion of RT in the AF group was caused by increases in both dispersion of MAP duration and dispersion of AT. CONCLUSION: During SR and PS, DAR increased in patients with paroxysmal AF due to increases in dispersion of MAP duration and dispersion of AT, which suggests the involvement of both repolarization and conduction disturbances in the development of paroxysmal AF.

Action Potentials↗

PubMed2003

Stress/strain/life revisited. Quantification by blood pressure chronomics: benetensive, transtensive or maletensive chrono-vasculo-neuro-immuno-modulation.

We propose to initiate the automatic self-assessment of wear and tear as "stress and strain" by the time structures of blood pressure (BP) and heart rate (HR), in order to arrive eventually at an individualized timely and timed routine of life and to early preventive intervention as soon as needed. The routine may involve physiological scheduling of physical and mental activities and meals, and if need be of non-drug or drug treatment for stress amplification, e.g., by exercise, and/or strain (not stress) relief by relaxation. In so doing, we recognize the circulation as a pillar and marker of preventive and active neuroimmunomodulation (NIM), suggesting that some concerns of a vasculo- and broader NIM can be quantified by transdisciplinary chronobiology using its cartography--chronomics--of time structures, i.e., chronomes, from chronos = time and nomos = rule. Thus, we are introducing the chronomics of BP, HR and of other variables in the historical context of pioneers who were indispensable to experimental medicine. We build upon their contributions, but we must point out when, in the past, by necessity rather than choice, the giants provided rationalizing truisms that are no substitute for systematic serial data collection and appropriate computer analysis. A time-unspecified spotcheck as a baseline is much better than no measurement, but very often it is not enough, and it is always insufficient when an estimate of variability constitutes the information needed. For dynamic cycles, there are only reference cycles as a routine, although when maps are available, single timed spotchecks can be invaluable. With reference to their historical context, here we rely only upon data which necessity, rather than philosophy, compels us to collect.

Activities of Daily Living↗

PubMed1995

Physical and genetic map of the Lactococcus lactis subsp. cremoris MG1363 chromosome: comparison with that of Lactococcus lactis subsp. lactis IL 1403 reveals a large genome inversion.

A physical and genetic map of the chromosome of the Lactococcus lactis subsp. cremoris reference strain MG1363 was established. The physical map was constructed for NotI, ApaI, and SmaI enzymes by using a strategy that combines creation of new rare restriction sites by the random-integration vector pRL1 and ordering of restriction fragments by indirect end-labeling experiments. The MG1363 chromosome appeared to be circular and 2,560 kb long. Seventy-seven chromosomal markers were located on the physical map by hybridization experiments. Integration via homologous recombination of pRC1-derived plasmids allowed a more precise location of some lactococcal genes and determination of their orientation on the chromosome. The MG1363 chromosome contains six rRNA operons; five are clustered within 15% of the chromosome and transcribed in the same direction. Comparison of the L. lactis subsp. cremoris MG1363 physical map with those of the two L. lactis subsp. lactis strains IL1403 and DL11 revealed a high degree of restriction polymorphism. At the genetic organization level, despite an overall conservation of gene organization, strain MG1363 presents a large inversion of half of the genome in the region containing the rRNA operons.

Bacteriophages↗

PubMed1996

Mixed quantum mechanical/molecular mechanical simulations of chemical reactions in solution and in enzymes by the classical trajectory mapping approach.

We present a practical hybrid quantum mechanical/molecular mechanical approach to study chemical reactions in solution and in enzymes. In this method, referred to as the "Classical Trajectory Mapping" method, trajectories are calculated on the classical potential surfaces and, by using the classical surfaces as a reference state for the actual quantum mechanical ground state potential, the free energy profile of the chemical reaction is obtained by the free energy perturbation technique. This method was applied to proton-transfer reactions both in aqueous solution and in papain. The encouraging results indicate the applicability of our method to chemical reactions in the condensed phase and the biological systems.

Calorimetry↗

PubMed1995

FISH mapping of 22 novel X chromosome cosmids and the isolation of a novel microsatellite on proximal Xp.

Twenty-two X-linked cosmid clones have been localised by fluorescence in situ hybridisation (FISH). Twelve map to the long arm of the X chromosome and 10 to the short arm. Seven of the latter cosmids and an additional one were mapped by two colour FISH relative to reference markers DXS7 and DXS426 in proximal Xp. Finer localisation of one of the cosmids, namely HX43 was achieved by isolation of a microsatellite followed by genetic mapping with respect to reference markers in the region.

Base Sequence↗

PubMed1988

Mapping of event-related desynchronization and type of derivation.

Event-related desynchronization (ERD) is a term describing alpha band amplitude changes in response to an event (stimulus presentation, self-paced movement, etc.). ERD mapping is a brain-imaging technique used to display the topographical pattern and time course of alpha power changes. Multi-lead EEG data referred to one ear were recorded during voluntary finger movements. From these data, transverse bipolar, source and common average reference derivations and the laplacian operator were calculated, and ERD maps are computed. The ERD is enhanced and best localized with the laplacian operator method, or with source derivations. ERD maps with ear reference required cautious interpretation.

Alpha Rhythm↗

PubMed1991

Use of high coverage reference libraries of Drosophila melanogaster for relational data analysis. A step towards mapping and sequencing of the genome.

Three differently made, primary Drosophila cosmid libraries of 16-fold genome coverage have been generated. Also, a jumping library has been created by a new method that takes advantage of methylation differences between genomic DNA and vector. Thirdly, two cDNA libraries have been picked. All these libraries have been arrayed on high-density in situ filters, each containing 9216 clones. As a reference system, such filters are distributed and identified clones are provided. Single-copy probes have identified on average 1.4 cosmids per genome equivalent. Together with cytogenetically mapped yeast artificial chromosomes, the libraries are also being used for physically mapping the genome, mainly by oligonucleotide fingerprinting and pool hybridizations. cDNA clones are further examined by a partial sequencing analysis by oligomer hybridization.

Animals↗

PubMed1995

Usefulness of omp1 restriction mapping for avian Chlamydia psittaci isolate differentiation.

Sixty-five avian Chlamydia psittaci isolates collected worldwide, including 27 previously characterized reference strains, were analysed by restriction mapping of the major outer membrane protein gene (omp1) obtained after DNA amplification by PCR. They were compared to 2 ruminant isolates, a feline pneumonitis and a guinea pig inclusion conjunctivitis (GPIC) isolate. According to their omp1 restriction patterns, avian strains were heterogeneous in that they exhibited 6 and 4 distinct patterns using AluI and MboII restriction enzymes, respectively, thus defining 7 groups. However, 84% of the studied strains belonged to groups 1 to 4, which share a specific fragment triplet of 411, 282 and 102 base pairs in their AluI digestion patterns. Comparisons with serological classifications showed a strict correlation and allowed further intraserovar differentiation. Furthermore, this classification based upon a single gene (omp1) roughly correlated with the data obtained by RFLP of native DNA and DNA/DNA hybridization studies. There was no host or geographic specificity in the pattern exhibited by these strains. The ruminant, feline pneumonitis and GPIC C. psittaci isolates were clearly distinguished from each other and the avian strains. Moreover, this method was clearly able to identify dubiously designated strains as well as mixtures of isolates within a single sample. In conclusion, this PCR approach based upon omp1 restriction mapping enables the differentiation of avian C. psittaci isolates and can be proposed as a taxonomic and epidemiologic tool.

Animals↗