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At least 1,693 records · Page 94Linked to original sources
PubMed2004

[Morphogenesis in formative process in vitro from Rehmannia glutinosa].

OBJECTIVE: To study the morphogenesis in formative process of tuberous root in vitro from Rehmannia glutinosa and compare the anatomical shape of tuberous root with nature term R. glutinosa. METHOD: Tuberous roots of different vegetal phase were cut and dyed, then made into paraffin cuts and observed microscope. RESULT AND CONCLUSION: In anatomical shape, nature R. glutinosa and tuberous root were the same, which showed that no structural variation occurred in tuberous root induced process.

Plant Roots↗
PubMedDate not supplied

Evaluating multidisciplinary child abuse and neglect teams: a research agenda.

A review of child welfare research literature reveals used to investigate and intervene in child abuse and neglect cases, the field does not know enough about their structural variations, implementation processes, or effectiveness. Moreover, although articles advocating multidisciplinary teams enumerate their apparent strengths, they lack attention to the teams' possible weaknesses. The article discusses implications for future evaluation studies.

Case Management↗
PubMed2005

[The role of phospholipase D in cellular signaling].

Phospholipase D (PLD) hydrolyzes structural phospholipids of biological membrane to produce phosphatidic acid (PA) and a free-head group. Both of these compounds can participate in signal transduction. Since the activation of PLD involved in many cellular signaling cascades was identified in recent years, knowledge of and interest in PLD have grown greatly, and significant progress has been made toward understanding PLD. This paper reviewed the research progress on gene structure, regulation and cellular function of PLD. PLDs are encoded by a multiple heterogenous gene family. The overall domain structures of plant PLDs are similar, but important differences occur in some of the motifs. The small structural variations underlie distinct regulatory and catalytic properties and cellular function in signaling. PA and other messengers produced by other phospholipase pathways can be interconverted with the action of lipid kinase and phosphatase. PLD is thought to function as an integral part of a network involving other lipid-signaling enzymes and messengers. Some research evidence demonstrated the specificity of PLDs in signal transduction with plant species, cell types, stimuli and cellular processes. Some important questions about PLD study were also raised.

Models, Biological↗
PubMed2006

Comparative analyses of population structure in two subspecies of Nigella degenii: evidence for diversifying selection on pollen-color dimorphisms.

Flower color can be a major determinant of plant fitness, not only because of preferential visitation by pollinators but also because of pleiotropic relationships between the expression of floral pigments and biochemically related compounds that influence vegetative performance variables. Different environments may therefore favor different pigmentation phenotypes. We examined whether spatially varying selection has played a major role in shaping large-scale patterns of differentiation in two subspecies of Nigella degenii (Ranunculaceae), with particular emphasis on pollen color. The two subspecies appear to have been genetically isolated for substantial periods of time and, therefore, provide a "replicated test" for the effect of natural selection. Estimates of population structure based on a suite of floral and vegetative characters were compared with the corresponding data for amplified fragment length polymorphism (AFLP) markers, which were assumed to be selectively neutral. We found low levels of genetic structure within the subspecies using both the AFLP markers (FST < or = 0.05) and quantitative characters (QST < or = 0.15), with no statistically significant differences between the two measures. There is, therefore, no evidence of diversifying selection being important in structuring variation in quantitative characters within each of the two subspecies. In contrast, estimates of differentiation in pollen color (FST > or = 0.10) significantly exceeded the neutral expectations (estimated from AFLP data), suggesting that local adaptation has played a key role in the evolution of this monogenic character.

Analysis of Variance↗
PubMedDate not supplied

[Features of the structure and evolution of complex tandemly organized Bsp-repeats in the fox genome. II. Tissue-specific and recombinant BamHI-dimer sites].

The complex structure of the clustered Bsp-repeats in fox genome seems to have evolved throughout a long period of time as a result of multiplication, recombination and divergence events. The sequence of the subrepeat (SR) approximately 245 b.p long is the basic substructure for the hierarchically arranged Bam HI-repeat 1468 b.p. long. The monomer consists of 3 SRs with a 43-59% homology. A dimer is composed of 2 monomers with a 93% homology. Amplification of the Bsp-repeats during evolution seems to have occurred at least twice: first--on the SR ancestral form level, second--on the monomer level. Despite profound divergence, there are still conservative regions in SRs with sequences homologous to known functional sites in eukaryotes. However qualitative and quantitative composition of most functional motifs is stringently individual in every SR. The performed analysis revealed that throughout evolution SRs acquired significant amount of motifs homologous to promoter and enhancer regions in tissue-specific genes and virus regulatory regions. Functional motifs in separate SRs are being differently grouped. Most inducible motifs are located in the III and II subrepeats, putative promoters--in the II one; elements participating both in transcriptional and replicational processes--mainly in the I subrepeat. A few ensembles of functional motifs remotely resemble extended regulatory regions of some tissue-specific genes. The monomers are potentially capable of ensuring diverse aspects of transcriptional regulation. As a whole, motifs of the 3 SRs are potentially capable of regulating the RNA synthesis periodicity with respect to the cellular cycle, activation and repression of genetical material in response to signals from the environment (AP-1, AP-2, AP-4, T-antigen, etc) and temporal ("octamers") etc. Apart from the BamHI-dimer, a few homologues fragments were isolated from fox genome and sequenced. Some of them were rearranged with respect to the BamHI-dimer. Inversion locally alters the composition of motifs and the sequence acquires new functional potential. Thus, the analysis of the emergence and development of Bsp-repeat structural variations allows us to consider repetitive DNA sequences as an ideal material in constructing multiprofile regulatory sequences.

Animals↗
PubMed1991

1-Peptidyl-2-haloacetyl hydrazines as active site directed inhibitors of papain and cathepsin B.

Fifteen 1-peptidyl-2-haloacetyl hydrazines, which can be considered halometanes of azapeptides containing Phe in P2 and alpha-aza-Ala or alpha-aza-Gly in P1, were synthesized and tested as models of cysteine-proteases inhibitors. By use of kinetic methods, they proved to irreversibly inactivate papain and cathepsin B via a reversible enzyme-inhibitor intermediate. Second-order rate constants of inactivation in the range 26-23000 M-1s-1 were observed for papain and 2000-39600 M-1s-1 for cathepsin B. KI for the reversible EI adducts ranged from 230 to 0.16 microM for papain and from 11 to 0.37 microM for cathepsin B. Structure of possible reversible EI complex is proposed and used to discuss the effects of structural variation of the inhibitors on the kinetic parameters of inactivation. Title compounds proved to be selective for cysteine-proteases, since no inhibiting activity could be detected toward trypsin, chymotrypsin and porcine pancreatic elastase at 0.1 mM concentration, after 6 h incubation. Relatively low aspecific alkylating properties were also verified in tests using glutathione as the nucleophile.

Animals↗
PubMed1991

Nodular regenerative hyperplasia of the liver: the importance of combined macroscopic and microscopic findings.

A 40-year-old man with rheumatoid arthritis, splenomegaly and mild thrombocytopenia presented with gross ascites and a history of excess alcohol consumption. Oesophageal varices were documented endoscopically. Alcoholic cirrhosis was suspected and laparoscopy revealed a macronodular liver surface. Liver biopsy disclosed subtle microscopic structural variations which together with the laparoscopic findings were consistent with the diagnosis of nodular regenerative hyperplasia. The importance in diagnosis of macroscopic appearance combined with histological findings is emphasised. Clinically significant portal hypertension may be present at a histologically early stage of this condition.

Adult↗
PubMed1990

Diagnosis and treatment of incomplete rotator cuff tears.

The histopathologic changes leading to rotator cuff rupture are gradual and progressive. Incomplete tears can be observed in the articular or bursal surface. These partial lesions are infrequently demonstrated with arthrography or bursography. Although structural variations in cuff integrity can be demonstrated with ultrasound or magnetic resonance imaging, precise definition of partial tears is difficult. The exact location and extent of incomplete tears can be documented with shoulder arthroscopy. Anterior acromioplasty, either open or arthroscopic, is indicated for the treatment of chronic mechanical impingement refractory to conservative management. When a sizable partial defect is identified at open surgery, the degenerated tissue is excised and the tendon is reattached to bone or repaired with side-to-side suture. Arthroscopic treatment consists of debridement of the torn cuff margins, followed by arthroscopic subacromial decompression (ASD). When the incomplete tear in an active individual involves more than one-half the cuff thickness, arthroscopic and open techniques can be combined. Twenty partial-thickness tears were encountered among 130 patients who had ASD for chronic impingement. Fifteen had a satisfactory result, but five required additional surgery. A system of grading partial-thickness tears based on location, depth, and area is presented in an effort to standardize the observations of various investigators and to permit comparison of the results of arthroscopic treatment.

Humans↗
PubMed1990

Highly polymorphic apolipoprotein A-IV locus in the baboon.

Apolipoprotein A-IV is found in mesenteric lymph chylomicrons, very low density lipoprotein particles, high density lipoprotein particles, and in the lipoprotein-free fraction of plasma. Apolipoprotein A-IV is polymorphic in a variety of species including human, dog, and horse. Efforts to estimate the impact of apolipoprotein A-IV structural variation on quantitative lipid levels in humans have been limited by the low frequency of the less common alleles. In the baboon, Papio hamadryas anubis, we have found apolipoprotein A-IV to be highly variable at the protein level with five alleles appearing at polymorphic frequency. We have confirmed the autosomal codominant inheritance of these five alleles in pedigreed baboons. The baboon has been shown to be a suitable animal model for the study of atherosclerosis, and the existence of a common, multi-allele apolipoprotein A-IV polymorphism in the baboon may be useful in elucidating the role of apolipoprotein A-IV in lipid metabolism.

Alleles↗
PubMed1987

The M gamma chain of human fetal hemoglobin.

A new gamma chain of human fetal hemoglobin, the M gamma chain, has been detected by high performance liquid chromatography (HPLC). It is characterized by a Leu----Met replacement at position gamma 141; no other structural variations have been found. The M gamma chain has been observed in red cell lysates of subjects with a heterozygosity for one of many types of hereditary persistence of fetal hemoglobin (HPFH), in sickle cell anemia, and in a few cord blood samples. At present, the genetic cause of this newly discovered heterogeneity is not known; an infidelity in translation or the existence of an unrecognized gamma globin gene should be considered.

Amino Acid Sequence↗
PubMed1988

Molecular-genetic evidence for the relationship of Mycobacterium leprae to slow-growing pathogenic mycobacteria.

A total of 1170 nucleotides of the 16S rRNA from Mycobacterium leprae were compared to the homologous regions of M. tuberculosis, M. bovis Vallée, M. avium, M. scrofulaceum, M. phlei, M. fortuitum and one representative each of the genera Corynebacterium, Nocardia, and Rhodococcus. Homology values were calculated and a phylogenetic tree was constructed from the evolutionary distance values. Despite differences in DNA G + C content and genome size, M. leprae is a true member of the slow-growing pathogenic mycobacteria, branching off intermediate to the other members of this subgroup. Slow- and fast-growing mycobacteria are phylogenetically well separated but constitute an individual branch of the actinomycetes proper. Significant structural variation of certain regions of the 16S rRNA may allow construction of M. leprae-specific probes used for rapid identification.

Animals↗
PubMed1989

T-cell clones recognizing MHC products.

A variety of factors may influence the reactivity of T cells with MHC products. In some cases, reactivity is dominantly influenced by one or a limited number of amino acid substitutions in the MHC molecule. Combinatorial epitopes that are dependent upon both alpha and beta chains can also be generated. MHC products, even from distinctive evolutionary backgrounds, may exhibit large regions of shared sequence, explaining patterns of clonal reactivity that would indicate the presence of shared epitopes. In other cases, epitopes may be truly cross reactive in nature, without regions of shared sequence. Indeed a limited number of clones may actually recognize either a class I or a class II MHC product. Finally, there are some patterns of clonal reactivity that cannot be explained by known structural variations. These clones either may recognize mixed class II dimers or may be influenced by peptide fragments presented in the groove of MHC gene products. This latter issue in particular requires a careful reconsideration of the process of allorecognition.

Clone Cells↗
PubMed1989

Functional morphology of the jaw muscles of two species of imperial pigeons, Ducula aenea nicobarica and Ducula badia insignis.

1. The functional morphological study of the jaw muscles of 2 species of Imperial Pigeons, Ducula aenea nicobarica and Ducula badia insignis has revealed that the structural variations of the bill, osteological and connective tissue elements, and muscles of the jaw apparatus may be correlated to functional diversity in the fruit-eating adaptation of these birds. 2. Both the species of Ducula possess moderately long, thick and stout bill with flexion zones inside, elongated orbital process of the quadrate, stout pterygoid, broad palatine and wide mandibular ramus on either side with increased retroarticular space. Such skeletal modifications together with increased orbital space indicate wide attachment-sites for the muscles, aponeuroses, tendons, and ligaments. 3. The morphology of the quadrato-mandibular joints suggests possible 'coupled kinesis' of the upper jaw, along with depression of the lower jaw. However, in a rhynchokinetic upper jaw as possessed by these birds, the kinesis is just moderate. Hence the gape of the mouth is mainly effected by the depression of the lower jaw, rather less so by the protraction of the upper jaw. 4. Among the functional groups of muscles, M. depressor mandibulae, M. adductor mandibulae externus, M. pseudotemporalis profundus, and M. pterygoideus are especially well developed. The various components of these muscles are provided with stiff as well as wide aponeuroses and tendons (much stronger than those observed in Columba), indicating forceful opening and closure of the beaks for plucking off the fruit, grasping it hard and manipulating it with the help of the beaks before swallowing. 5. The fleshy insertion of the outer slip of M. pseudotemporalis profundus extends ventrally over the dorsolateral surface of the mandible much more than it does in Columba. Further, 2 short and stiff aponeuroses at the rostral insertion of the inner slip of the muscle increase the force of adduction on the mandible. 6. M. adductor mandibulae posterior has not only wider origin and insertion, but also greater mass of fibres than that observed in Columba. 7. M. adductor mandibulae externus and M. pterygoideus form muscle-complexes with the predominance of bipinnate and multipinnate arrangements of fibres and with occasional joining fibres between their components. Such arrangements of fibres indicate sustained force-production, rather than faster movements of the jaw apparatus. 8. M. pterygoideus ventralis lateralis has a well developed 'venter externus' slip which has its thick and fleshy insertion on the outer lateral angular and articular mandible.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[Various rhythmologic precursors of terminal arrhythmia in patients with myocardial infarct].

The presence of near one hour ultradian cardiac rhythm was revealed on the ECG of 24 patients with acute myocardial infarction during 24-hour Holter monitoring. A classification of the phases of near one hour rhythm was developed according to the first coefficient value of autocorrelation of cardiac rhythm function. Special attention was attracted to the critical phase indicating high probability of the development of terminal arrhythmia and the threatening phase preceding it. Peculiarities of the variational structure of cardiac rhythm in the threatening phase and physical prerequisites of its origination are discussed.

Heart Arrest↗
PubMed1987

Thermal properties of chemically modified cytochrome c.

Differential scanning calorimetry was used as a probe to follow structural disturbances in cytochrome c with electrostatic modification. At 51.7% maleylation, the Td decreased 14.1 degrees C; however, relatively stable delta H values reflected minor structural variations. With 77.5 and 96.4% modification, a significant decrease in delta H was more indicative of major conformational change. On this basis, a critical labelling point was considered. Extensive maleylation (96.4%) did not result in complete cytochrome denaturation. In general, assessment of cytochrome thermal parameters by DSC provided a conformational perspective for the influence of specific electrostatic parameters on molecular integrity.

Animals↗
PubMed1986

Two dimensional gel analysis of HLA-DR2 associated HLA-D clusters.

Five cell lines with different cellular HLA-D specificities associated with HLA-DR2, i.e. Dw2, Dw12, MN2, DB9 and D2J, displayed structural variation in the products of the DR and DQ loci. Analyses of immunoprecipitated DR molecules from HLA-D homozygous B-lymphoblastoid cell lines by two dimensional polyacrylamide gel electrophoresis showed variable patterns with one set of DR beta chains. Another set of DR beta chain products, however, was homogeneous in all cell lines studied. In addition, analyses of DQ molecules showed extremely variant DQ beta chains, and slightly variant DQ alpha chains.

B-Lymphocytes↗
PubMed1988

The teichoic acids of actinomycetes.

The discovery of teichoic acids in the cell walls of a number of actinomycetes suggests that these polymers are widespread in the order Actinomycetales. Structural variations in the teichoic acids are described and their possible physiological functions are discussed.

Actinomyces↗
PubMed1986

A discontinuous small subunit ribosomal RNA in Tetrahymena pyriformis mitochondria.

We show here that in the mitochondria of Tetrahymena pyriformis, the small subunit (SSU) rRNA is discontinuous, being comprised of two separate components which we term "alpha" (a novel low molecular weight RNA, approximately equal to 200 nucleotides long) and "beta" (a previously described 14 S RNA). The SSU alpha rRNA has been sequenced in its entirety; it represents the immediate 5'-terminal domain of conventional SSU rRNA. The sequences at the ends of the SSU beta rRNA have also been determined; they show that this molecule corresponds to the 3'-terminal 7/8 of conventional SSU rRNA. A 2.5-kilobase pair XbaI restriction fragment of T. pyriformis mitochondrial DNA which contains the SSU alpha and SSU beta rRNA genes was cloned and its complete nucleotide sequence was determined. This revealed that the genes encoding the two segments of SSU rRNA are separated by a 54-base pair (A + T)-rich spacer. The alpha and beta sequences can be fitted to a generalized secondary structure model for eubacterial 16 S rRNA, with the two RNA species associating through long range interactions to form base-paired regions characteristic of SSU rRNA. In this model, the spacer is situated in a region of pronounced primary and secondary structural variation among SSU rRNAs. The significance of these findings with respect to rRNA biosynthesis and processing and the possible evolutionary relationship between spacers and variable regions in rRNA genes is discussed.

Animals↗