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At least 253 records · Page 14Linked to original sources
PubMed1999

An auxin-dependent distal organizer of pattern and polarity in the Arabidopsis root.

Root formation in plants involves the continuous interpretation of positional cues. Physiological studies have linked root formation to auxins. An auxin response element displays a maximum in the Arabidopsis root and we investigate its developmental significance. Auxin response mutants reduce the maximum or its perception, and interfere with distal root patterning. Polar auxin transport mutants affect its localization and distal pattern. Polar auxin transport inhibitors cause dramatic relocalization of the maximum, and associated changes in pattern and polarity. Auxin application and laser ablations correlate root pattern with a maximum adjacent to the vascular bundle. Our data indicate that an auxin maximum at a vascular boundary establishes a distal organizer in the root.

Arabidopsis↗
PubMed1990

Flavonoid Accumulation Is Correlated with Adventitious Roots Formation in Eucalyptus gunnii Hook Micropropagated through Axillary Bud Stimulation.

Eucalyptus gunnii Hook microcuttings, obtained in vitro through axillary bud stimulation, show different rooting responses on the same rooting medium depending on the physiological state induced by cytokinins used in the previous multiplication medium. 6-Furfurylamino purine and 6-(4-hydroxy-3-methylbut-2-enylamino)purine induced a physiological state characterized by high sensitivity of microcuttings to the rooting stimulus exerted by the auxin 3-indolebutyric acid, but N(6)-benzyladenine did not produce the same effect. The former physiological state was characterized by an increased accumulation of two endogenous flavonoids (identified as quercetin glycosides) which may be markers of a well defined physiological state. They could have some direct influence on the rooting processes of the explants cultivated in vitro.

Journal Article↗
PubMed1979

Morphological features of functionally defined neurons in the marginal zone and substantia gelatinosa of the spinal dorsal horn.

Functional characteristics of spinal neurons located in the marginal zone (lamina I) and substantia gelatinosa (lamina II) were compared to their structural features by intrcellularly staining the source of unitary potentials with horseradish peroxidase (HRP) in unanesthetized, spinal cats. The responses of postsynaptic units to graded electrical volleys in intact dorsal roots and to physiological stimulation revealed that the peripheral excitatory input to neurons of the region is dominated by slowly conducting afferent fibers; often, the input to a given element is largely from a particular class of receptors. One type commonly seen received its principal peripheral excitation from low threshold mechanoreceptors with A delta or C afferent fibers. Mechanoreceptive elements often exhibited a marked, prolonged habituation and many were not excited by afferent volleys. Other units were predominantly excited by nociceptors with myelinated or unmyelinated fibers, or by thermoreceptors with unmyelinated fibers. A few units (principally the thermoreceptive) showed substantial ongoing activity which was modulated by sensory stimulation, but most had little or none. The HRP staining revealed neuronal morphology in fine detail. No relationship between neuronal configuration and physiological response was discerned. Soma location was not always linked to afferent input, although the cell bodies of nociceptive and thermoreceptive neurons tended to be in lamina I or outer lamina II (SGo) while those of the innocuous mechanoreceptive meurons tended to be in inner lamina II (SGi). The locus of a neuron's major dendritic arborization was more closely related to the source(s) of peripheral excitation. Cells excited by nociceptors with myelinated fibers had major dendritic projections in the marginal zone. Cells excited by nociceptors or thermoreceptors with unmyelinated fibers had important dendritic branching in the SGo. Innocuous mechanoreceptive neurons had primary dendritic arborization in the SGi when the input derived from unmyelinated fibers, or in the SGi and extending into the outer nucleus proprius (lamina III) when the afferent drive came from A delta fibers. These findings support the concept that laminae I and II constitute a major termination region for thin primary afferent fibers, myelinated fibers from nociceptors ending principally in lamina I and unmyelinated fibers from nociceptors, thermoreceptors, and mechanoreceptros terminating predominantly in lamina II. Substantial integrative and distributive functions can be expected of such an afferent termination zone.

Animals↗
PubMed2002

Calcitonin gene-related peptide immunoreactive sensory DRG neurons innervating the cervical facet joints in rats.

The rat C5/6 facet joint is innervated multisegmentally from the C3 to the T3 dorsal root ganglia. Sensory fibers from the C3, C4, and C7-T3 dorsal root ganglia were reported to be innervated nonsegmentally through the paravertebral sympathetic trunks, while those from the C5 and C6 dorsal root ganglia were reported to segmentally innervate the C5/6 facet joint. The presence of calcitonin gene-related peptide-immunoreactive nerve fibers has been proved in the facet joints, but their ratios have not been studied. Fluoro-gold-labeled neurons innervating the C5/6 facet joint were distributed throughout the dorsal root ganglia from the C3 to T3 levels. Of the fluoro-gold-labeled neurons, the ratios of calcitonin gene-related peptide-immunoreactive C3, C4, C45 C6, C7, C8, T1, T2, and T3 dorsal root ganglion neurons were 30%, 22%, 43%, 47%, 21%, 19%, 25%, 36%, and 40%, respectively. The ratios of calcitonin gene-related peptide-immunoreactive neurons in the C5 and C6 dorsal root ganglia were significantly higher than those in the C3, C4, C7, and C8 dorsal root ganglia. In the physiological condition in rats, the neurons of the C5 and C6 dorsal root ganglia may have a more significant role in pain sensation of the facets than other dorsal root ganglion neurons.

Animals↗
PubMed1987

Auditory evoked potentials to continuous amplitude-modulated sounds: can they be described by linear models?

The responses from the round window of the cochlea and the surface of the cochlear nucleus to continuous tones and noise that were amplitude-modulated with pseudorandom noise were studied. The responses were averaged with the averager locked to the periodicity of the pseudorandom noise, and the cross-correlation between the averaged responses and one period of the pseudorandom noise was computed. The degrees of non-linearities in the responses were estimated by comparing the response of a linear model that had this cross-correlogram as its impulse response and the physiological response. The root mean square (RMS) value of the histograms increases as a function of the stimulus intensity and reaches a peak at 40-60 dB above threshold, above which intensity it decreases. The non-linear component of the response increases monotonically with sound intensity in the range from threshold to 60-70 dB above threshold. The pseudorandom noise was of the inverse-repeat type, and when even-order non-linearities were canceled by subtracting the latter half of the responses to one period of the pseudorandom noise from the first half a much closer agreement with the model responses was obtained, indicating that the non-linearities were mainly of even order. It was concluded that the non-linearities of the responses may have been caused by an unequal response to increases and decreases in stimulus intensity.

Acoustic Stimulation↗
PubMed1989

Utilization of sweet potatoes in controlled ecological life support systems (CELSS).

A number of studies have selected the sweet potato as a potentially important crop for CELSS. Most hydroponic studies of sweet potatoes have been short term (<80 days). Full term (90 to 150 days) studies of sweet potatoes in hydroponic systems were needed to understand the physiology of storage root enlargement and to evaluate sweet potato production potential for CELSS. Early and late maturing sweet potato varieties were crown in hydroponic systems of different types--static with periodic replacement, flowing with and without recirculation, aggregate, and non-aggregate. In a flowing system with recirculation designed at Tuskegee University using the nutrient film technique (NFT), storage root yields as high as 1790 g were produced with an edible growth rate of up to 66 g m-2 d-1 and a harvest index as high as 89% under greenhouse conditions. Preliminary experiments indicated high yields can be obtained in controlled environmental chambers. Significant cultivar differences were found in all systems studied. Nutritive composition of storage roots and foliage were similar to field-grown plants. The results indicate great potential for sweet potato in CELSS.

Biomass↗
PubMed2005

Characterization of lucidin formation in Rubia tinctorum L.

In order to approach lucidin formation (a strong mutagen or a carcinogen) from a physiological standpoint, hairy roots of Rubia tinctorum L. were established by a transformation of Agrobacterium rhizogenes strain 15834 and cultured in a liquid woody plant medium without plant hormones. The anthraquinone pigment composition of the intact hairy roots was essentially the same as that of the intact non-transformed (normal) roots, in which lucidin O-beta-D-primeveroside (LuP) was one of the major pigments. Lucidin was scarcely detected in the intact hairy roots, but was a main pigment after the squash treatment. The crude protein extract of intact hairy roots exhibited LuP-glycosidase activity (an activity converting LuP to lucidin). This activity was also detected in the roots of the normal plants at a high level, but slightly in the stems and not in the leaves. Methyl jasmonate enhanced the LuP production and LuP-glycosidase activity in the hairy roots. On the other hand, ethephon or salicylic acid had either no effect or rather an inhibitory effect on them. After partial purification of LuP glycosidase, the resultant active fraction producing a major band with an apparent Mr of 68 kDa exhibited the substrate specificity for both aglycon and sugar-moiety. The sugar released from LuP by this fraction was neither D-glucose nor D-xylose and was hydrolyzed into them. These results suggest that LuP specific beta-primeverosidase (EC 3.2.1.149) exists in the roots of R. tinctorum and is involved in the systematic defense system.

Anthraquinones↗
PubMed1995

Time, magic, and gynecology: contemporary Israeli practice.

This paper describes the way in which a simple device, the pregnancy wheel, has been used by the medical profession to impose a new way of measuring and experiencing pregnancy. The change involves counting in weeks instead of counting in months and it is gradually replacing a commonsensical method that had deep physiological and cultural roots. In contrast, the medical methodology of counting forty weeks is more complicated and lacks direct connections to the events of pregnancy. In the encounter between the doctor and the pregnant woman the pregnancy wheel has a variety of uses, among them determinations of the age and estimated size of the fetus. It plays an additiional role, however, in the medicalization of pregnancy by providing the doctor with privileged information. It also influences modes of thinking through the way in which it deals with the question of the beginning of pregnancy, a question that has clear moral implications.

Female↗
PubMed2005

Articulatory complexity, ambient frequency, and functional load as predictors of consonant development in children.

The notion of a universal pattern of phonological development, rooted in basic physiological constraints, is controversial, with some researchers arguing for a strong environmental (ambient language) influence on phonological development or an interaction of both physiological constraints and ambient language effects. This research examines the relative value of articulatory complexity, ambient frequency, and functional load as predictors of consonant development in children. Three languages are investigated: Cantonese, American English, and Dutch. Regression analyses revealed that functional load accounted for 55% of the variance in age of emergence of consonants in 7 English-speaking children (8-25 months), while frequency of consonants in the ambient language accounted for 63% of the variance in age of emergence of consonants in 51 Cantonese-speaking children (15-30 months). Articulatory complexity accounted for 40% of the accuracy of production of consonants in 40 English-speaking children (25 months), and frequency accounted for 43% of the variance in accuracy of production of consonants in 5 Dutch-speaking children (24 months). Given cross-linguistic differences, further research is required.

Child Language↗
PubMed2003

Identification of glycosylphosphatidylinositol-anchored proteins in Arabidopsis. A proteomic and genomic analysis.

In a recent bioinformatic analysis, we predicted the presence of multiple families of cell surface glycosylphosphatidylinositol (GPI)-anchored proteins (GAPs) in Arabidopsis (G.H.H. Borner, D.J. Sherrier, T.J. Stevens, I.T. Arkin, P. Dupree [2002] Plant Physiol 129: 486-499). A number of publications have since demonstrated the importance of predicted GAPs in diverse physiological processes including root development, cell wall integrity, and adhesion. However, direct experimental evidence for their GPI anchoring is mostly lacking. Here, we present the first, to our knowledge, large-scale proteomic identification of plant GAPs. Triton X-114 phase partitioning and sensitivity to phosphatidylinositol-specific phospholipase C were used to prepare GAP-rich fractions from Arabidopsis callus cells. Two-dimensional fluorescence difference gel electrophoresis and one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the existence of a large number of phospholipase C-sensitive Arabidopsis proteins. Using liquid chromatography-tandem mass spectrometry, 30 GAPs were identified, including six beta-1,3 glucanases, five phytocyanins, four fasciclin-like arabinogalactan proteins, four receptor-like proteins, two Hedgehog-interacting-like proteins, two putative glycerophosphodiesterases, a lipid transfer-like protein, a COBRA-like protein, SKU5, and SKS1. These results validate our previous bioinformatic analysis of the Arabidopsis protein database. Using the confirmed GAPs from the proteomic analysis to train the search algorithm, as well as improved genomic annotation, an updated in silico screen yielded 64 new candidates, raising the total to 248 predicted GAPs in Arabidopsis.

Arabidopsis↗
PubMed1992

Somal membrane properties of physiologically identified sensory neurons in the rat: effects of nerve growth factor.

1. Intracellular recordings were made in situ from physiologically identified dorsal root ganglion (DRG) cells in untreated rats aged 5-8 wk and in rats treated from birth to 5 wk of age with nerve growth factor (NGF) or antisera against NGF (anti-NGF). 2. As demonstrated in cats, the shape of the somal action potential (AP) of DRG cells of normal rats is correlated with peripheral receptor type. Cells that innervate high-threshold mechanoreceptors (HTMRs) and thus respond to noxious stimulation of skin or deep tissue in the periphery have long-duration APs characterized by an inflection on the falling limb of the spike. Cells that innervate low-threshold mechanoreceptors (LTMRs) have briefer APs that lack the inflection. Somal APs of neurons supplying HTMRs tend to be larger in amplitude, have slower peak rates of rise, and on average have longer afterhyperpolarizations than those innervating LTMRs. 3. It was also found that the somal APs of HTMRs were not blocked by 200 microM tetrodotoxin (TTX) applied directly to the surface of the ganglion. In contrast, those of LTMRs were rapidly and irreversibly blocked. Despite the difference in the sensitivity of the soma, axonal conduction in both types of cells was abolished by TTX. 4. Chronic treatment with NGF resulted in an increase in duration of the falling limb of the spike compared with untreated control animals or animals treated with preimmune rabbit serum. This was true only in cells that had long duration APs to begin with, i.e., HTMRs. LTMRs were unaffected by the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed2001

[Mid-term results of stentless bioprosthesis for aortic valve replacement. Experience in a series of 97 patients].

Stentless bioprostheses have been described as valve substitutes of interest for aortic valvular replacement. We studied 97 consecutive patients with a mean age of 72.2 years (40-84) who underwent aortic valvular replacement with 80 Toronto SPV and 17 Freestyle prostheses. Operative mortality was 6.2. With a mean follow-up of 19 +/- 10 months (1-46), 87.2% of the surviving 86 patients underwent an echocardiography performed by the same operator. Mean gradient was 10.9 +/- 3.6 mmHg (4.2-22.6) and effective orifice area was 1.8 +/- 0.5 cm2 (0.8-3.0) for the 75 controlled stentless valves. The best haemodynamic data were obtained with the 25 mm diameter prostheses. One asymptomatic partial dehiscence was observed during monitoring. None of the 15 detected aortic leaks was significant. We observed a significant reduction of the ventricular mass in 41 patients who had undergone pre- and postoperative evaluation (p < 0.0014). Overall survival was 86.8 +/- 4.4% at 2 years. Stentless bioprostheses offered satisfactory haemodynamic results in our series. They however require an implantation technique learning curve as well as a thorough knowledge of the aortic root anatomy and physiology.

Adult↗
PubMedDate not supplied

[Results of treatment of milk teeth pulp by modified formocresol method].

The purpose of the study was evaluation of the results of treatment of molar pulp diseases by the formocresol method from the standpoint of the development of inflammatory complications in periapical tissues, disturbances of physiological resorption of roots, disturbances of mineralization of crowns of homologous permanent teeth. For the treatment milk molars were qualified with the diagnosis of grade II pulpopathy in children aged from 3 to 9 years. The treatment was done using formocresol by a modified method of pulp amputation according to Buckley after previous devitalization with parapaste. The status of 143 teeth was examined again 1 to 4 years after completion of treatment. The proportion of positive results after one year was 94%, after two years it was 90%, after three years 87% and after four years 80%. The cause of premature loss of most teeth was root resorption acceleration by 18-24 months. No harmful action of formocresol on the buds of permanent teeth was noted.

Child↗
PubMedDate not supplied

Histological observations of teeth and peridental tissues in cleidocranial dysplasia imply increased activity of odontogenic epithelium and abnormal bone remodeling.

Cleidocranial dysplasia (CCD) is a heritable generalized bone dysplasia presenting with a variety of dental abnormalities. To delineate morphological features of the dental tissues, we have analyzed histologically the structure of teeth and peridental tissues obtained from four CCD patients. Dentin appeared regular, except when formed in response to caries, physiological attrition or root resorption. Both acellular and cellular cementum were present in deciduous teeth, whereas in permanent teeth, cellular cementum was virtually lacking and acellular cementum was partially hyperplastic. Enamel pearls were seen in the furcations of one deciduous and one permanent molar. The roots of most deciduous teeth were resorbed only to a slight extent. Morphologically, supernumerary teeth resembled their normal counterparts. Denticles as well as epithelial cell clusters were occasionally present in the root pulps of deciduous teeth. In the peridental tissues, epithelium was locally abundant, and the cytokeratin profile confirmed its odontogenic origin. While the organization pattern of the alveolar bone matrix related to unshed deciduous teeth and unerupted permanent teeth varied, woven bone was abundant. Both formative and resorption surfaces were seen. Also, reversal lines were prominent, suggesting that the bone had, in fact, undergone remodeling. While no direct association between the aberrant bone morphology and the multifarious histological abnormalities of dental tissues can be established, the local abundance of odontogenic epithelium in peridental tissues of developing/unerupted as well as fully developed teeth may be causally related to the formation of excess acellular cementum, enamel pearls and supernumerary teeth.

Adolescent↗
PubMedDate not supplied

Three-dimensional coupled fluid-structure simulation of pericardial bioprosthetic aortic valve function.

A computational, three-dimensional coupled fluid-structure dynamics model was developed for a generic pericardial aortic valve in a rigid aortic root graft with physiologic sinuses. Valve geometry was based on that of the natural valve. Blood flow was modeled as pulsatile, laminar, Newtonian, incompressible flow. The structural model accounted for material and geometric nonlinearities and also simulated leaflet coaptation. A body fitted grid was used to subdivide the flow domain into computational finite volume cells. Shell finite elements were used to discretize the leaflet volume. A finite volume computational fluid dynamics code and finite element structure dynamics code were used to solve the flow and structure equations, respectively. The fluid flow and structural equations were coupled using an implicit "influence coefficient" technique. Physiologic ventricular and aortic pressure waveforms were prescribed as the flow boundary conditions. The aortic flow field, valve structural configuration, and leaflet stresses were computed at 2 msec intervals. Model predictions on aortic flow and transient variation in valve orifice area were in close agreement with corresponding experimental in vitro data. These findings suggest that the computer model has potential for being a powerful design tool for bioprosthetic aortic valves.

Algorithms↗
PubMed2004

Analysis of receptive fields revealed by in vivo patch-clamp recordings from dorsal horn neurons and in situ intracellular recordings from dorsal root ganglion neurons.

It has been thought that spinal dorsal horn neurons receive convergent inputs from not only somatosensory but also visceral pathways. For instance, the referred pain is presumed to be due to the convergence of sensory inputs from cardiac and shoulder receptive fields. However, precise investigation has not been made from dorsal horn neurons yet, because of difficulty in studying the pathways from those regions by means of conventional electrophysiology. The purpose of this study is to clarify the convergent inputs to single dorsal horn neurons from wide receptive fields using an in vivo patch-clamp recording technique from the superficial spinal dorsal horn and an intracellular recording from dorsal root ganglion neurons that keep physiological connections with the peripheral sites. Identified dorsal root ganglion neurons received an input from a quite small area, about 1 x 1 mm in width of the skin. In contrast, substantia gelatinosa neurons in the spinal cord received inputs from an unexpectedly wide area of the skin. Previous extracellular recordings have, however, revealed that substantia gelatinosa neurons have small receptive field. This discrepancy is probably due mainly to an availability of the in vivo patch-clamp method to analyze sub-threshold synaptic responses. In contrast, the extracellular recording technique allows us to analyze predominantly the firing frequency of neurons. Thus, the in vivo patch-clamp recordings from dorsal horn neurons and the intracellular recordings from DRG neurons will be useful for well understanding the sensory processing in the spinal cord.

Animals↗
PubMed2004

Short on phosphate: plant surveillance and countermeasures.

Metabolism depends on inorganic phosphate (P(i)) as reactant, allosteric effector and regulatory moiety in covalent protein modification. To cope with P(i) shortage (a common situation in many ecosystems), plants activate a set of adaptive responses to enhance P(i) recycling and acquisition by reprogramming metabolism and restructuring root system architecture. The physiology of P(i) starvation responses has become well understood, and so current research focuses on the initial molecular events that sense, transmit and integrate information about external and internal P(i) status. Recent studies have provided evidence for P(i) as a signaling molecule and initial insight into the coordination of P(i) deficiency responses at the cellular and molecular level.

Adaptation, Physiological↗