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At least 325 records · Page 18Linked to original sources
PubMed1990

Antibiotic SB22484: a novel complex of the aurodox group. II. Structure elucidation of the four factors.

SB22484, active against Neisseriae gonorrhoeae and Neisseriae meningitidis, is a complex of four factors, designed 1 through 4, which from two pairs of isomers, 1 and 3, and 2 and 4. Factors 1 and 3 account for 65% of the complex, factor 3 being the predominant one. On the basis of the existing and implemented correlations between structure and physico-chemical characteristics (UV and IR spectroscopies, ionization properties, MS as FAB and as negative and positive CI, 1H NMR spectroscopy as 2D COSY and NOESY) in the aurodox field, the complete structures were assigned. Factor 3 can be described as N-[7-[5(R)-[7-[1,2-dihydro-4-hydroxy-1H-2-oxo-3-pyridinyl]-6-methyl- 7-oxo-1(E),3(E),5(E)-heptatrienyl]tetrahydro-3(S),4(R)-dihydrox yfuran-2 (S)-yl]-6(S)-methoxy-5,7(R)-dimethyl-2(E),4(E)-heptadienyl]-alpha (S)-methyl-5(S)-methyltetrahydro-2(S),4(S or R)-dihydroxy-6(S)-[1(E), 3(Z)-pentadienyl]-2H-pyran-2-acetamide. Factor 1 is an epimer of factor 3 with the opposite configuration at the anomeric center. Factors 2 and 4 have an ethyl group instead of the methyl group alpha to the acetamide moiety and are in the same stereochemical relationship as the pair 1 and 3.

Acid-Base Equilibrium↗
PubMed2000

Persistent effects of a structured psychiatric intervention on breast cancer patients' emotions.

The aim of the present study was to investigate persistence of the clinical effectiveness of a 5-weekly structured group intervention program for Japanese breast cancer patients. Each program is a series of five 90-min sessions, which include psycho-education, problem-solving, psychological support, relaxation training, and guided imagery. Fifty-seven patients with breast cancer participated in the program and the 47 who completed were analyzed. The results of the Profile of Mood States (POMS) scores were compared before, just after, and 6 months after the intervention. According to the change in POMS scores, the clinical effectiveness of a structured group intervention program persisted for 6 months for the patients who had no psychiatric diagnoses at entry. By contrast, this 5-weekly intervention program did not show persistent effects for patients who had a psychiatric diagnosis at entry. Therefore, additional intervention would be needed for patients with psychiatric diagnosis at entry.

Adjustment Disorders↗
PubMed1983

Head group and structure specific interactions of enkephalins and dynorphin with liposomes: investigation by hydrophobic photolabeling.

The interaction of the opioid enkephalins and endorphins with lipid bilayers is largely unknown. Such interactions might, however, be important for understanding the molecular mechanisms of biological action. We have therefore studied the interaction of several enkephalins and of dynorphin-(1-13)-tridecapeptide (dynorphin1-13) with model membrane systems, using the extremely hydrophobic photolabel of J. Brunner and G. Semenza, (Biochemistry 20, 7174-7182 (1981)) 3-trifluoromethyl-3-(m[125I]iodophenyl)diazirine. By observing several limitations of the method, it was possible to characterize hydrophobic interactions of opioid peptides with liposomes prepared from egg yolk phosphatidylcholine (PC) plus dipalmitoylphosphatidic acid (PA), from brain phosphatidylserine (PS) alone, and from brain cerebroside sulfate (CS) alone, Dynorphine1-13 exhibited strong hydrophobic interactions through its N-terminal "message" segment which were potentiated by the "address" that itself remained in the aqueous phase. This behavior was consistent with the reported pharmacological potentiation. The enkephalins were generally weakly labeled in the PC/PA and PS systems. However, in the CS systems the preferentially mu agonists were labeled very strongly whereas the preferentially delta agonists were labeled more weakly yet. The kappa agonist, dynorphin1-13, was strongly, but more equally labeled in the three systems. Thus, there was a head group specificity that, in our series of compounds, correlated with opiate receptor sub-type specificity. The results were consistent with the behavior of the mu agonist, morphine.

Amino Acid Sequence↗
PubMed1993

Treatment of hospitalized patients with complicated skin and skin structure infections: double-blind, randomized, multicenter study of piperacillin-tazobactam versus ticarcillin-clavulanate. The Piperacillin/Tazobactam Skin and Skin Structure Study Group.

We compared the efficacy and safety of two beta-lactam-beta-lactamase inhibitor combinations, namely, piperacillin-tazobactam and ticarcillin-clavulanate, in the treatment of complicated bacterial infections of skin that required hospitalization. The study was a randomized, double-blind, comparative trial involving 20 centers. The infections were classified as (i) cellulitis with drainage, (ii) cutaneous abscess, (iii) diabetic or ischemic foot infection, and (iv) infected wounds and ulcers with drainage. The clinical response rates were comparable for the two treatment regimens (61% of the patients were cured with piperacillin-tazobactam and ticarcillin-clavulanate and improvement was seen in 15 and 16% of patients treated with piperacillin-tazobactam and ticarcillin-clavulanate, respectively). Both regimens were found to be safe and well tolerated. These data support the use of piperacillin-tazobactam for initial empiric therapy of hospitalized patients with complicated skin and skin structure infections.

Bacteroides Infections↗
PubMed2005

Small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) studies of amide phospholipids.

Varying chemically the structure of phospholipids in the region between hydrophobic and hydrophilic segments is expected to have a strong influence on the interaction with water and the phase behavior. This is studied in this work with the motivation to investigate these lipids as potential inhibitors of phospholipase A2. Thus the amide phospholipids L-ether-amide-PC (1-O-hexadecyl-2-N-palmitoyl-2-amino-2-deoxy-sn-glycero-3-phosphocholine), L-ester-amide-PC (1-palmitoyl-2-N-palmitoyl-2-amino-2-deoxy-sn-glycero-3-phosphocholine) and L-ether-amide-PE (1-O-hexadecyl-2-N-palmitoyl-2-deoxy-sn-glycero-3-phosphoethanolamine) have been synthesized and characterized. The phase behavior and thermal transitions in buffer dispersions are examined by a combination of high-sensitivity differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) experiments between 10 and 80 degrees C at pH 8.9. The onset temperatures determined from DSC measurements agree well with the starting temperatures of changes in the repeat distance obtained by SAXS measurements. The phases observed are lamellar both below and above the main phase transition. The phase transition temperatures and enthalpies depend strongly on the substitutions in sn-1 position and head group structure. The lamellar repeat distance in gel and liquid-crystalline phases increases with increasing temperature for L-ester-amide-PC and L-ether-amide-PC, whereas the temperature dependence is opposite for the L-ether-amide-PE. The observed behavior is discussed and compared with that of DPPC and DPPE, indicating the strong dependence of hydration and phase behavior on head group structure.

Amides↗
PubMed2002

Permutation-validated principal components analysis of microarray data.

BACKGROUND: In microarray data analysis, the comparison of gene-expression profiles with respect to different conditions and the selection of biologically interesting genes are crucial tasks. Multivariate statistical methods have been applied to analyze these large datasets. Less work has been published concerning the assessment of the reliability of gene-selection procedures. Here we describe a method to assess reliability in multivariate microarray data analysis using permutation-validated principal components analysis (PCA). The approach is designed for microarray data with a group structure. RESULTS: We used PCA to detect the major sources of variance underlying the hybridization conditions followed by gene selection based on PCA-derived and permutation-based test statistics. We validated our method by applying it to well characterized yeast cell-cycle data and to two datasets from our laboratory. We could describe the major sources of variance, select informative genes and visualize the relationship of genes and arrays. We observed differences in the level of the explained variance and the interpretability of the selected genes. CONCLUSIONS: Combining data visualization and permutation-based gene selection, permutation-validated PCA enables one to illustrate gene-expression variance between several conditions and to select genes by taking into account the relationship of between-group to within-group variance of genes. The method can be used to extract the leading sources of variance from microarray data, to visualize relationships between genes and hybridizations and to select informative genes in a statistically reliable manner. This selection accounts for the level of reproducibility of replicates or group structure as well as gene-specific scatter. Visualization of the data can support a straightforward biological interpretation.

Animals↗
PubMed1977

The common marmoset (Callithrix jacchus jacchus) as a model for ethological research.

The uses and advantages of the common marmoset (Callithrix jacchus jacchus) as an animal model for ethological research were examined. It was found that this species had advantages over Old World primates for work on social behavior as a nearer approximation to the group structure occurring in natural conditions could be obtained in the laboratory. The small size of the common marmoset also made it easier to handle and cheaper to maintain. The adult female gave birth at five-month intervals and usually reared twin offspring. This, and the short generation time, made it an ideal model for mother-infant behavioral studies. The common marmoset was also shown to be a useful model for studies of social play, especially for categorizing the changes in playful behavior with age, and the relationship of the patterns seen in play to other behaviors. It was also suggested that it may be an ideal model for experimental studies of play. Other suggested uses included studies of the relationship of food supply and feeding habits to territory size and group structure, and of the advantages to elder offspring of helping to rear younger siblings. As a result of these observations the common marmoset was considered to have great potential as a model for ethological research, both in its natural habitat and in the laboratory.

Aggression↗
PubMed1979

Validity of medical staff judgments in establishing quality assurance priorities.

The validation of a structured group judgment procedure to establish priorities for quality assurance activities was undertaken in six medical institutions in the United States. Validation focused on the extent to which health improvement could be documented by outcome-based projects focusing on priority topics. Predictive (criterion-related) validity was sought by analyzing five successively more stringent levels of evidence: 1) feasibility of implementing a quality assessment project within the topic areas selected by the prioity procedure; 2) accuracy of identifying health deficiencies or strengths; 3) verification of establishing correctable causes of health deficiencies; 4) capability of effecting significant improvement of health deficiencies; and 5) credibility of evidence that improvement achieved is directly attributable to corrective actions taken. Within the limits of generalizability, predictive validity was documented at every level of analysis. It is recommended that the structured group judgment process used in this study be more thoroughly evaluated and considered for quality assurance planning purposes.

Decision Making↗
PubMed1994

Non-congruent relationships between variation in emm gene sequences and the population genetic structure of group A streptococci.

To examine the molecular population genetics of the M protein family of Streptococcus pyogenes (group A Streptococcus), the 5' regions of polymerase chain reaction-amplified emm products from 79 M serotypes were sequenced and the phylogeny was compared to estimates of overall genetic relationships among strains determined by multilocus enzyme electrophoresis. Although the 5' emm sequences from several strains designated as distinct M types were identical or almost identical, the overall pattern is characterized by very extensive variation. The composition of distinct emm sequence clusters generally parallels the ability of strains to express serum opacity factor and in some cases historical associations of certain M types with acute rheumatic fever, but not with M types classified as nephritogenic. For many strains there is a lack of congruency between variation in 5' emm sequences and estimates of overall chromosomal relationships, which is undoubtedly due to horizontal transfer and recombination of emm sequences. The results of these studies provide insights into the nature and extent of emm sequence variation and describe how this variation 'maps' onto the population genetic structure of extant S. pyogenes lineages. The complexity of emm sequence and streptococcal cell lineage relationships revealed by this analysis has significant implications for understanding evolutionary events generating strain diversity and the epidemiology of S. pyogenes diseases.

Amino Acid Sequence↗
PubMed2000

Molecular characterisation of two structurally distinct groups of human homers, generated by extensive alternative splicing.

Homer proteins bind specifically to the C termini of the metabotropic glutamate receptor mGluR1alpha/a and mGluR5, play a role in their targeting and modulate their synaptic properties. We have discovered that extensive alternative splicing generates a family of 17 Homer proteins. These fall into two distinct groups of 12 "long" Homers, which all have a coiled-coil domain at their C termini, and five "short" Homers, which lack such a domain. All Homers contain the N-terminal sequence responsible for their binding to mGluR1alpha/a receptors and can be co-localised with the recombinantly expressed mGluR1alpha/a protein in HEK-293 cells. The existence of the long and the short variants of each of the Homer-1, Homer-2 and Homer-3 proteins reflects the fundamental principles of Homer functions.

Alternative Splicing↗
PubMed1995

A comparison of neutron diffraction and molecular dynamics structures: hydroxyl group and water molecule orientations in trypsin.

A comparison is presented of experimentally observed hydroxyl and water hydrogen atoms in trypsin determined from neutron density maps with the results of a 140 ps molecular dynamics simulation. Experimental determination of hydrogen and deuterium atom positions in molecules as large as proteins is a unique capability of neutron diffraction. The comparison addresses the degree to which a standard force-field approach can adequately describe the local electrostatic and van der Waals forces that determine the orientations of these hydrogen atoms. The molecular dynamics simulation, based on the all-atom AMBER force-field, allowed free rotation of all hydroxyl groups and movement of water molecules making up a bath surrounding the protein. The neutron densities, derived from 2.1 A 2H2O-H2O difference Fourier maps, provide a database of 27 well-ordered hydroxyl hydrogen atoms. Virtually all of the simulated hydroxyl orientations are within a standard deviation of the experimentally observed positions, including several examples in which both the simulation and the neutron density indicate that a hydroxyl group is shifted from a "standard" rotamer. For the most highly ordered water molecules, the hydrogen distributions calculated from the trajectory were in good agreement with neutron density; simulated water molecules that displayed multiple hydrogen-bonding networks had correspondingly broadened neutron density profiles. This comparison was facilitated by development of a method to construct a pseudo 2 A density map based on the hydrogen atom distributions from the simulation. This method is particularly useful for statically disordered water molecules, in which the average location assigned from a trajectory may represent a site of relatively low occupancy. The degree of disorder of internal water molecules is shown to result primarily from the electrostatic environment surrounding that water molecule as opposed to the cavity size available to the molecule.

Crystallography, X-Ray↗
PubMed1990

A comparison study of antidepressants and structured intensive group psychotherapy in the treatment of bulimia nervosa.

Previous research on the treatment of outpatients with bulimia nervosa has focused on two treatment strategies: (1) drug therapy, primarily using tricyclic antidepressants, and (2) psychotherapy, often employing behavioral and cognitive behavioral techniques. We report here the short-term treatment outcome of a 12-week comparison trial of bulimic outpatients who were randomly assigned to one of four treatment cells: (1) imipramine hydrochloride treatment, (2) placebo treatment, (3) imipramine treatment combined with intensive group psychotherapy, and (4) placebo treatment combined with intensive group psychotherapy. All three active treatment cells resulted in significant reductions in target-eating behaviors and in a significant improvement in mood relative to placebo treatment. However, the results also suggested that the amount of improvement obtained with the intensive group psychotherapy component was superior to that obtained with antidepressant treatment alone. The addition of antidepressant treatment to the intensive group psychotherapy component did not significantly improve outcome over intensive group psychotherapy combined with placebo treatment in terms of eating behavior, but did result in more improvement in the symptoms of depression and anxiety.

Adolescent↗
PubMed1999

Population structure and group composition of western lowland gorillas in north-western Republic of Congo.

Population studies are an essential part of conservation actions. Under exceptional observation conditions we studied a western lowland gorilla population visiting the Maya salt-clearing (north of the Parc national d'Odzala, P.N.O., Congo) over an 8 month period; 36 groups and 18 solitary individuals (a total of 420 individuals) have been identified visiting the clearing, which suggests a high gorilla density in the region. Ninety-six percent of the gorillas entered the clearing in groups. One-male groups had a mean size of 11.2. Ninety percent of solitary individuals were silver-back males. Compared with other populations of both lowland gorillas and mountain gorillas, the Maya population had the highest immature rate and the highest number of infants per female. Ecological correlates that could explain the attractiveness of the Maya clearing are discussed. The present status and the renewal rate of the Maya population indicate the need for further studies and confirm the importance of developing eco-tourism in this region as part of the sustainable park management activities developed by the ECOFAC programme (European Union). The results also provide arguments to support the proposal for extending the P.N.O. to include this region, which is rich in salt-clearings and attracts many other key-species of mammal such as forest elephants.

Animals↗
PubMed2000

Porphyrins and metalloporphyrins: versatile circular dichroic reporter groups for structural studies.

During the last few years, porphyrins and metalloporphyrins have attracted widespread attention as chromophores for studies in circular dichroism (CD), an indispensable chiroptical tool for monitoring chiral interactions. This review summarizes the multifaceted properties of porphyrins and metalloporphyrins, powerful CD chromophores that are characterized by their intense and red-shifted Soret band, propensity to undergo pi-pi stacking, facile incorporation of metals, and ease in varying solubility. Such attributes make porphyrins one of the most attractive and sensitive chromophores used in CD studies. They offer possibilities for studying the stereochemistry of chiral porphyrin assemblies, large organic molecules, biopolymers, and compounds available in miniscule quantities. The tendency of porphyrins to undergo pi-pi stacking and zinc porphyrins to coordinate with amines enable the CD exciton chirality method to be extended to configurational assignments of flexible compounds containing only one stereogenic center. Various artificial porphyrin receptors have been synthesized for the recognition of biologically important chiral guests such as carbohydrates, amino acids, and their derivatives. The induced CD of the host porphyrin Soret band reflects the identity of guests and binding modes of host/guest complexation with high sensitivity.

Circular Dichroism↗
PubMed2006

Oligoethylene chains terminated by ferrocenyl end groups: synthesis, structural properties, and two-dimensional self-assembly on surfaces.

A series of unsaturated long-chain-bridged diferrocenes Fc-(CH2)n-CH=CH-(CH2)n-Fc (4 a-e) was synthesized by means of olefin metathesis. Subsequent catalytic hydrogenation furnished the saturated alpha,omega-bis-ferrrocenyl oligoethylene products Fc-(CH2)m-Fc (5). Members of both series formed highly ordered laminar structures at the highly oriented pyrolytic graphite (HOPG) solid/liquid interface or on the Ag(110) surface, which were characterized by STM. Details of the structural features of these ordered physisorbed surface assemblies of 4 and 5 were analyzed by comparison with DFT calculations on model systems and with the characteristic packing modes of these systems in the crystal.

Journal Article↗
PubMed1995

Sequence and putative secondary structure of group I introns in the nuclear-encoded ribosomal RNA genes of the fungus Hymenoscyphus ericae.

Two putative group I introns in the nuclear ribosomal RNA genes of Hymenoscyphus ericae are described. One is in the small subunit gene about 30 nucleotides upstream of the 3' end of the gene at a site common to several other group I introns. The other is in the large subunit gene approx. 930 bp downstream of the 5' end of the gene. This is the only report of an intron at this location.

Ascomycota↗