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PubMed1996

Influence of experimental occlusal discrepancy on masticatory muscle activity during clenching.

The influence of the experimental occlusal discrepancy on masticatory muscle activity was investigated on 12 subjects. Specially designed occlusal interferences were fabricated and various occlusal states were simulated with their aid. Subjects were asked to carry out eccentric clenching efforts and electromyographic activity of the masseter plus the anterior and posterior temporal muscles was measured. When compared with clenching on the unaltered natural dentition, clenching on the experimental interferences resulted in distinct patterns in the jaw elevator muscles, and the most characteristic change was observed when clenching effort was exerted on the experimental non-working side interference. Electromyographic activity in the anterior and posterior temporal muscles was decreased on the working side and increased on the non-working side and originally unilateral activity pattern with clear dominance on the working side was altered to a bilateral pattern, while that of the masseter muscles remained uninfluenced. Resultant bilateral activity in the anterior and posterior temporal muscles is thought to cause a superior movement of the working side condyle and an inferior movement of the non-working side condyle.

Adult↗
PubMed2003

Polyphyletic origin of cultivated rice: based on the interspersion pattern of SINEs.

The wild rice species Oryza rufipogon with wide intraspecific variation is thought to be the progenitor of the cultivated rice species Oryza sativa with two ecotypes, japonica and indica. To determine the origin of cultivated rice, subfamily members of the rice retroposon p-SINE1, which show insertion polymorphism in the O. sativa -O. rufipogon population, were identified and used to "bar code" each of 101 cultivated and wild rice strains based on the presence or absence of the p-SINE1 members at the respective loci. A phylogenetic tree constructed based on the bar codes given to the rice strains showed that O. sativa strains were classified into two groups corresponding to japonica and indica, whereas O. rufipogon strains were in four groups, in which annual O. rufipogon strains formed a single group, differing from the perennial O. rufipogon strains of the other three groups. Japonica strains were closely related to the O. rufipogon perennial strains of one group, and the indica strains were closely related to the O. rufipogon annual strains, indicating that O. sativa has been derived polyphyletically from O. rufipogon. The subfamily members of p-SINE1 constitute a powerful tool for studying the classification and relationship of rice strains, even when one has limited knowledge of morphology, taxonomy, physiology, and biochemistry of rice strains.

Animals↗
PubMed1984

Cytogenetic studies on recipients of allogeneic bone marrow using the sex chromosomes as markers of cellular origin.

In 45 patients whose donor was of unlike sex, the sex chromosomes were used as markers of the cellular origin of myeloid and lymphoid tissues after allogeneic bone marrow transplantation (BMT). Successful engraftment was characterized by the appearance of dividing donor cells in marrow within 2 weeks of grafting and in mitogen stimulated blood cultures by 3 weeks. Leukaemic relapse was identified in eight cases and was associated with different patterns of cellular origin of the myeloid and lymphoid tissues. At the time of relapse the marrow contained either a mixed population of normal donor and leukaemic recipient cells, or only recipient cells. Thus, in this series, leukaemic relapse was not found occurring in donor cells. The importance of defining the origin of cells in interphase as well as in metaphase was demonstrated. In all but one case, the dividing lymphoid population remained of donor origin during relapse.

Adolescent↗
PubMed1998

Hypothetical neural mechanism that may play a role in mental rotation: an attractor neural network model.

We propose an attractor neural network (ANN) model that performs rotation-invariant pattern recognition in such a way that it can account for a neural mechanism being involved in the image transformation accompanying the experience of mental rotation. We compared the performance of our ANN model with the results of the chronometric psychophysical experiments of Cooper and Shepard (Cooper L A and Shepard R N 1973 Visual Information Processing (New York: Academic) pp 204-7) on discrimination of alphanumeric characters presented in various angular departures from their canonical upright position. Comparing the times required for pattern retrieval in its canonical upright position with the reaction times of human subjects, we found agreement in that (i) retrieval times for clockwise and anticlockwise departures of the same angular magnitude (up to 180 degrees) were not different, (ii) retrieval times increased with departure from upright and (iii) increased more sharply as departure from upright approached 180 degrees. The rotation-invariant retrieval of the activity pattern has been accomplished by means of the modified algorithm of Dotsenko (Dotsenko V S 1988 J. Phys. A: Math. Gen. 21 L783-7) proposed for translation-, rotation- and size-invariant pattern recognition, which uses relaxation of neuronal firing thresholds to guide the evolution of the ANN in state space towards the desired memory attractor. The dynamics of neuronal relaxation has been modified for storage and retrieval of low-activity patterns and the original gradient optimization of threshold dynamics has been replaced with optimization by simulated annealing.

Algorithms↗
PubMed2003

Clinical correlates of frontal intermittent rhythmic delta activity in children.

Frontal intermittent rhythmic delta activity is an electrographic pattern of unclear origin. Previously thought to correlate with deep midline and infratentorial pathology, rather, it appears to be associated with encephalopathy states in adults. The significance of frontal intermittent rhythmic delta activity in children has not been studied. We analyzed the electrographic characteristics and clinical associations of pediatric frontal intermittent rhythmic delta activity. This pattern was rarely detected, occurring in 20 of 1500 electroencephalographic (EEG) studies. Patients' ages ranged between 1.5 and 17 years. Most patients were awake and showed no signs of acute encephalopathy when frontal intermittent rhythmic delta activity occurred. Half of the children were cognitively impaired, and half had a history of epilepsy. Epileptiform activity was present in 55% of the EEG recordings. However, frontal intermittent rhythmic delta activity was part of the epileptiform discharge in only a minority of cases. The duration of frontal intermittent rhythmic delta activity bursts was longer in the mentally retarded group. Most patients did not have structural brain pathology. None had deep midline or infratentorial lesions. In conclusion, frontal intermittent rhythmic delta activity is rare in children, is not associated with acute encephalopathy or with deep midline or infratentorial lesions, and tends to occur during wakefulness. The electrographic characteristics of frontal intermittent rhythmic delta activity appear to differ between cognitively normal and mentally retarded children.

Adolescent↗
PubMed2004

Corsifurans A-C, 2-arylbenzofurans of presumed stilbenoid origin from Corsinia coriandrina (Hepaticae).

Chemical investigation of the diethyl ether extract from the liverwort Corsinia coriandrina resulted in the isolation of a new 2-arylbenzofuran compound called corsifuran A. The structure was identified by spectroscopic techniques and confirmed by synthesis. Two minor constituents of similar structure, and two related stilbenoids and a bibenzyl were identified by comparison of the mass spectra and GC retention indices with authentic samples. Due to the similarity in substitution patterns a stilbenoid origin of the corsifurans is proposed.

Benzofurans↗
PubMed2005

A re-examination of the root cortex in wetland flowering plants with respect to aerenchyma.

AIMS: We review literature and present new observations on the differences among three general patterns of aerenchyma origin and their systematic distributions among the flowering plants, and we clarify terminology on root aerenchyma. SCOPE: From our own previous works and some new observations, we have analysed the root cortex in 85 species of 41 families in 21 orders of flowering plants that typically grow in wetlands to determine the characteristic patterns of aerenchyma. FINDINGS: A developmental and structural pattern that we term expansigeny, as manifested by honeycomb aerenchyma, is characteristic of all aquatic basal angiosperms (the Nymphaeales) and basal monocots (the Acorales). Expansigenous aerenchyma develops by expansion of intercellular spaces into lacunae by cell division and cell expansion. Schizogeny and lysigeny, so often characterized in recent reviews as the only patterns of root cortex lacunar formation, are present in most wetland plants, but are clearly not present in the most basal flowering plants. CONCLUSION: We conclude that expansigeny is the basic type of aerenchyma development in roots of flowering plants and that the presence of expansigenous honeycomb aerenchyma in root cortices was fundamental to the success of the earliest flowering plants found in wetland environments.

Climate↗
PubMed1992

Glial cells: possible determinants of neuronal uptake of tritiated proline.

When tritiated proline is injected into various sensory and integrative areas of the brain, it fails to be incorporated into the proteins of neuronal soma located within the injection site. In contrast, such incorporation does occur when [3H]proline is injected into dorsal root ganglia. The basis for this difference is unclear because brain and dorsal root ganglion tissue differ in configurational factors (e.g. synapses, dendrites) as well as in the embryological origin of their respective neuronal and non-neuronal cell populations. To determine if configurational factors might account for [3H]proline's incorporation into somal neuronal proteins in dorsal root ganglia, [3H]proline was injected into autonomic (pelvic and superior cervical) and sensory (dorsal root and nodose) ganglia in the rat. These ganglia differ in synaptic and cellular configurations, but have the same neural origin (neural crest). Virtually all neuronal soma were labeled in autoradiograms of all of these injection sites, suggesting that configurational factors do not account for the labeling of dorsal root ganglion neurons by [3H]proline. To address the issue of embryological origin, cellular labeling patterns after [3H]proline injection into the hypoglossal nucleus, dorsal motor nucleus of the vagus and the ventral horn of spinal cord were compared with those after [3H]proline injections into the adjacent solitary nucleus, gracile nucleus and central cervical nucleus of the spinal cord. The neurons in the former three nuclei (i.e. motoneurons) originate from the neural tube, but their axons are associated primarily with Schwann cells which originate from the neural crest. Although neurons in the latter three regions also originate from the neural tube, their axons are myelinated entirely by neural tube-derived glia (i.e. oligodendrocytes).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Origin of the sinus impulse.

It was generally accepted that the site of normal impulse origin within the atria was a single static focus within the sinus node. This review will examine how this model of impulse origin came about and has evolved. Early on, conflicting data suggested that the sinus node focus was not static and changed with interventions that changed heart rate, such as vagal stimulation. Furthermore, even with removal of the sinus node, a normal atrial rhythm was generated. High-resolution mapping in humans and dogs showed that the initiation of the impulse was dynamic and could be multicentric, with more than one focus initiating a single beat. Shifts in the site of origin correlated with changes in rate and were consistent with P wave changes routinely observed in the standard ECG. These studies suggested multiple pacemakers were responsible for impulse initiation. However, it was not clear how these widespread pacemakers were coordinated to function synchronously. Recent canine data suggest that the node may be partially insulated from the surrounding atrium, resulting in multicentric origin starting from a single site within the node. What has evolved is a model of impulse origin with a sinus node having discrete exit sites and a dominant pacemaker within the node that can shift to other nodal sites. Complex and changing conduction out of the node, coupled with extranodal pacemakers, which can assume dominance over the node, combine with the autonomic nervous system to control heart rate and the pattern of impulse origin within the atria.

Animals↗
PubMed1979

The development of the hippocampus and dentate gyrus in normal and reeler mice.

The histogenesis, the time of origin and the pattern of migration of the cells in the hippocampus and dentate gyrus, have been studied in normal and reeler mice. The earliest indication of a defect in the reeler hippocampus is seen on the fifteenth embryonic day (E15) which is at least 24 hours after the first indication of a defect in the neocortex. It is not until E18, that the dentate gyrus shows signs of its incipient abnormality. It appears then, that in both the hippocampus and the dentate gyrus the gene defect first manifests itself at the stage at which the definitive cellular layers are assembled. Experiments involving the injection of 3H-thymidine (3H-TdR) at different developmental stages have confirmed that the site and rate of cellular proliferation in the reeler hippocampus and dentate gyrus are normal, as is the initial pattern of cell migration. However, in the reeler dentate gyrus, most postnatal cell proliferation occurs ectopically and in the hippocampus the normal "inside-out" sequence of neurogenesis is reversed, the earliest pyramidal cells generated coming to lie superficially within the stratum pyramidale and the later formed cells being added at progressively deeper levels. There is no discernible gradient in the time of origin of the granule cells in the radial dimension of the reeler dentate gyrus, whereas there is an obvious "outside-in" gradient in the normal animal. The characteristic gradients in cell proliferation seen in the transverse and longitudinal dimensions of the normal dentate gyrus are, however, also evident in the reeler mouse. Taken together, these observations suggest that the reeler gene exerts its effect on neuronal position only in the radial dimension, and does so at a stage of development subsequent to the proliferation and initial migration of the relevant neurons. Timm's sulfide silver preparations indicate that the characteristic staining patterns seen in the dentate gyrus and hippocampus appear at the same time, and mature at the same rate in normal and reeler mice.

Animals↗
PubMed2000

Genetic heterogeneity in Mycobacterium tuberculosis isolates reflected in IS6110 restriction fragment length polymorphism patterns as low-intensity bands.

Mycobacterium tuberculosis isolates with identical IS6110 restriction fragment length polymorphism (RFLP) patterns are considered to originate from the same ancestral strain and thus to reflect ongoing transmission. In this study, we investigated 1,277 IS6110 RFLP patterns for the presence of multiple low-intensity bands (LIBs), which may indicate infections with multiple M. tuberculosis strains. We did not find any multiple LIBs, suggesting that multiple infections are rare in the Netherlands. However, we did observe a few LIBs in 94 patterns (7.4%) and examined the nature of this phenomenon. With single-colony cultures it was found that LIBs mostly represent mixed bacterial populations with slightly different RFLP patterns. Mixtures were expressed in RFLP patterns as LIBs when 10 to 30% of the DNA analyzed originated from a bacterial population with another RFLP pattern. Presumably, a part of the LIBs did not represent mixed bacterial populations, as in some clusters all strains exhibited LIBs in their RFLP patterns. The occurrence of LIBs was associated with increased age in patients. This may reflect either a gradual change of the bacterial population in the human body over time or IS6110-mediated genetic adaptation of M. tuberculosis to changes in the environmental conditions during the dormant state or reactivation thereafter.

Cluster Analysis↗
PubMed2005

Arteries in the posterior cervical triangle in man.

Due to frequent changes in the anatomical nomenclature of the arteries in the posterior cervical triangle (lateral cervical region), anatomical and surgical papers relating to these topics are sometimes difficult to understand and are hard to compare. These changes, coupled with improper knowledge of the gross anatomy and nomenclature of the arteries in the posterior cervical triangle, have presented difficulties in musculocutaneous flap planning, especially in plastic and reconstructive surgery. As an illustration of this concern, the term, transverse cervical artery (A. transversa colli [cervicis]), and its associated branches, have been used frequently over the past several decades with different meanings. In an effort to address this nomenclature challenge and to offer a rational basis for arguing specific name changes, a total of 498 neck-halves were investigated in Graz, Innsbruck, and Munich. Lateral neck dissections were carried out to expose the subclavian artery and those branches destined for the posterior cervical triangle, specifically, the superficial cervical artery, the dorsal scapular artery, and the suprascapular artery. The course of these arteries and details of their origins and branching patterns were documented. Several arose either as direct branches or from trunks. The convention used in labeling trunks was similar to that described for other trunk formations in the body (e.g., linguo-facial trunk). Four trunks were observed and named according to the branches that arose from each. A cervico-dorsal trunk gave origin to the superficial cervical and dorsal scapular arteries, and was found in 30% of cases. A cervico-scapular trunk gave rise to the superficial cervical and suprascapular arteries in 22% of cases, and a dorso-scapular trunk provided origins for the dorsal scapular and suprascapular arteries in 4% of cases. A cervico-dorso-scapular trunk gave origin to the superficial cervical artery, the dorsal scapular artery, and the suprascapular artery, and was found in 24% of cases. Each of these trunks, in turn, arose from either the subclavian artery or from the thyrocervical trunk. This labeling convention necessitated omitting the term, transverse cervical artery, because this term has become inherently imprecise and variously used over the years. This study describes a simple, uniform, and rational basis for standardizing the nomenclature of the arteries in the posterior cervical triangle.

Aged↗
PubMed2006

Gastrointestinal stromal tumours: experience with multislice CT.

PURPOSE: The aim of this study was to evaluate the possibilities of multislice computed tomography (MSCT) in the identification and characterisation of gastrointestinal stromal tumours (GISTs). MATERIALS AND METHODS: MSCT images of 27 patients affected by GIST were analysed. MSCT scans were performed before and after contrast medium injection, and bowel distension was obtained with the administration of water, air or a diluted Gastrografin solution. Images were evaluated for presence and site of the tumour, origin and growth pattern relative to the bowel wall, density, relationship with adjacent structures and evidence of lymph nodes and metastases. RESULTS: GISTs were located in the stomach in 18/27 patients, in the small bowel in seven, in the oesophagus in one and in the rectum in one. Tumour size ranged from 1.5 cm to 21 cm. An extramucosal origin was definitely established in 23/27 cases. In 15/27 cases, the lesions exhibited extramural growth, and in 17/27 cases, they were homogeneous after contrast medium injection. The borders were regular in 17 cases. Hepatic metastases were detected in 5/27 cases, and lymphadenomegaly was found in one case only. CONCLUSIONS: Nowadays, MSCT can be considered an essential tool for the diagnosis of GISTs, as it enables one to detect the disease, define its relationships and search for possible metastases.

Adult↗
PubMed1984

Intrinsic factor secretion from isolated gastric mucosal cells of rat and man--two different patterns of secretagogue control.

Intrinsic Factor (IF) secretion was studied using isolated gastric mucosal cells from rat and man. In the rat, IF was localized to the chief cells and its secretion responded most efficaciously to carbachol. DbcAMP and hexoprenaline were less powerful, whereas histamine and pentagastrin lacked any effect. In man, IF secretion derived from the parietal cells and was increasingly enhanced by hexoprenaline, pentagastrin, carbachol, histamine and dbcAMP. In both species, IF secretion differs with respect to its cellular origin and the pattern of secretagogue control: IF release from rat chief cells is due to muscarinic receptor excitation, whereas IF release from human parietal cells responds predominantly to histamine-H2-receptor activation and seems to be mediated by the cAMP system.

Adenylyl Cyclases↗
PubMed1975

An on-line transformation of EEG scalp potentials into orthogonal source derivations.

A new type of EEG derivation has been investigated. This derivation, constituting a practical implementation of the Laplace operator, detects source activity as it appears at the surface level of the scalp. It is realized in the 10-20 system of electrode placement basically as an analogue superposition of four bipolar derivations, forming a star-like configuration around each electrode. Visual estimation of the topographical origins of a pattern, is thus replaced by a more efficient on-line process, which derives the source activity at the position of each individual electrode. Practical correlation tests have shown that the separation of adjacent derivations is improved by a factor of between two and four, compared to the corresponding bipolar and common reference derivations. Any feature of local origin will therefore have a correspondingly increased signal-to-noise ratio prior to the stage of visual or automatic interpretation. As a consequence of the partition of the scalp field into 19 source zreas, instead of utilizing an arbitrary number of potential differences, one fixed montage with 19 recorder channels is sufficient to present the total surface activity, within the limits of resolution of the electrode system.

Data Display↗
PubMed1994

A practical approach to lifestyle change counselling in primary care.

Many contemporary medical conditions have been found to be the consequence of lifestyle choices. These adverse habit patterns have their origin in the individuals family and/or natural social network. Primary care practitioners frequently interact with their patients for the purpose of helping them resolve medical problems by clarifying issues or presenting different options. In lifestyle related conditions, the initiation and maintenance of possible behaviour changes is usually the optimal resolution. How people intentionally change well-established behaviour patterns is still not well understood, and most clinicians are not confident in their ability to help patients alter adverse behaviours. Several studies provide support for a 'stage-matched framework' of behaviour change that integrates readiness for change with intervention processes from various theoretical models. This article provides a brief overview of the current thinking with respect to self-initiated and professionally facilitated behaviour change, and then describes a generic five-step approach to individualized lifestyle counselling for use in primary care clinical settings.

Counseling↗
PubMed1996

Intermediate filaments in the nervous system: implications in cancer.

In this review, we describe the different intermediate filament (IF) proteins, their assembly into IFs, the functions of IFs and their relation to disease with a particular emphasis on the intermediate filaments expressed in the nervous system. In the mammalian nervous system, seven intermediate filament proteins are known to be expressed in neurons or neuroblasts. These include the three neurofilament triplet proteins, which are present in both central and peripheral neurons; alpha-internexin, which is the first neuronal intermediate filament protein expressed in the developing mammalian nervous system and present primarily in CNS neurons in the adult nervous system; peripherin, which is most abundant in the PNS; vimentin, which is expressed in neuronal progenitor cells along with nestin, as well as in a few adult neurons. In contrast to these neuron-specific IF proteins, the glial fibrillary acidic protein (GFAP) is glial specific and expressed in mature astrocytes. Vimentin and nestin are also expressed in glial progenitor cells and vimentin is expressed along with GFAP in some mature astrocytes. As a whole, the expression of IF proteins is tissue specific and developmentally regulated. As a result, IF proteins are good markers for determining the cell origin and differentiation status of tumor cells. For example, peripherin is expressed in neuroblastomas, GFAP in astrocytomas and neurofilaments in tumors of neuronal origin. However, tumor cells may express IF patterns which are irrelevant to their cell origin. Therefore, one has to be very careful in using IF patterns as sole indicators of cell origin and differentiation status of tumors.

Animals↗
PubMed2005

Smell intensity monitoring using metal oxide semiconductor odor sensors during intravenous olfaction test.

The intravenous olfaction test using prosultiamine (PST) solution is simple to perform and has been used clinically in Japan. We monitored intranasal intensity of smell continuously in real time under various conditions of administration using metal oxide semiconductor odor sensors and established an optimal PST injection procedure. In this study, we found that 1) although there was fluctuation in the pattern of intensity of increase in smell in the PST original solution test, the pattern of increase in intranasal smell intensity could be stabilized by prolonging the injection time to 40 s and 2) dilution of PST with physiological saline was effective in preventing angialgia during intravenous injection. It appears that PST administration is best performed by adding 10 ml of saline to 10 mg (2 ml) of PST and injecting the resulting 12-ml solution (6x dilution) and that the best respiratory cycle for testing is once in every 2 s.

Adult↗