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At least 55 records · Page 3Linked to original sources
PubMed1975

Cytophysiological basis of disruptive pigmentary patterns in the leopard frog Rana pipiens. II. Wild type and mutant cell-specific patterns.

A new pattern index, Ip, is introduced and used to compare patterns of wild type, burnsi, and kandiyohi chromatophores in the leopard frog, Rana pipiens. Wild type chromatophores are hyperdispersed over distances within cellular contact, and it is concluded that this hyperdispersion results from contact-mediated negative interactions. The hyperdispersion is less strong in spot cells than interspot, and extends over larger areas in burnsi than in wild type epidermis. Over areas greater than chromatophore size, patterns are either random or clumped. Patterning of kandiyohi melanophores is clumped into aggregates small enough to be within the range of cellular contact, suggesting a lack of contact inhibition among these cells. The possible roles of cellular properties and the extracellular environment in pattern determination are discussed.

Animals↗
PubMed1975

Chromosome banding pattern conservatism in birds and nonhomology of chromosome banding patterns between birds, turtles, snakes and amphibians.

The G-banded karyotypes of 4 species of birds representing the orders Galliformes, Columbiformes and Musophagiformes were compared. Banding pattern homology between orders was limited t 5o 5 major chromosome arms and the Z chromosome. Even in these major chromosome arms pericentric and paracentric inversions produced alteration of the banding pattern sequences. Addition of constitutive heterochromatin was responsible for changes in banding patterns in the Z chromosome. The chromosome banding patterns of an emydid turtle, Terrepene carolina, 5 species of boid snakes of the genera Liasis, Acrantophis, and Sanzinia and the African clawed-frog. Xenopus muelleri, were also compared to the bird chromosome banding patterns. No homology was observed between any of these major groups: bird, snake, turtle, amphibian. However, intergroup homology was apparent. - The data obtained do not support reports of broad interordinal direct homology of the macrochromosomes of birds and refutes the idea of a primitive bird karyotype with 3 pairs of "Agroup' chromosomes and 3 pairs of "B group' chromosomes. - The major mechanisms responsible for chromosome evolution in birds appear to be centric and tandem fusions, paracentric and pericentric inversions, and addition or deletion of heterochromatin.

Animals↗
PubMed1978

Patterns of output firing generated by a many-input neuronal model for different model parameters and patterns of synaptic drive.

A relatively simple neuronal model with a large number of 'synaptic' inputs is described. The model has been extensively studied in order to investigate the influence which patterns of presynaptic firing may have upon the pattern of output firing. The model has been studied in two versions. In one the threshold remained constant, while in the other the threshold was increased following an output firing. This increase in threshold decayed with time and was analogous to the after-hyperpolarization of a real neurone. The effect on the frequency of output firing of changes in the threshold and of the overall input rate were studied in detail. The pattern of output firing was studied for two patterns of input firing. In one, each presynaptic input fired steadily, each at a different rate; in the other, the input firings were randomly distributed in time, being generated by a Poisson process. It was found that, for a given total input rate, the pattern of output firing was markedly more regular when the input processes were regular, even though the mean rate of output firing was not appreciably different for the two different distributions of input firings. It is shown that, with suitable parameters for the model, it is possible to mimic very closely the discharge of tonically discharging motoneurones under different experimental conditions. This suggests that the more general properties of the model may have considerable relevance to the way in which real neurones integrate their synaptic input.

Action Potentials↗
PubMed1992

Phage pattern and antibiotic resistance pattern of coagulase-negative staphylococci obtained from immunocompromised patients.

A total of 152 coagulase-negative staphylococcal strains were isolated from clinical samples of 14 patients hospitalized after bone-marrow transplantation in a specialized hospital ward in Hungary, during an 18-month period between 1987 and 1989. Two species, Staphylococcus epidermidis and Staphylococcus haemolyticus, predominated (each, 45%). Using Pulverer and co-workers' phage set for typing, 68% of the isolates were typable; 16 phage patterns were observed. A characteristic long pattern with phages Ph10/Ph13/Ph15/U4/U15/U16/U20/U33 /U46 appeared only in S. epidermidis, among 5 of 11 colonized patients (8.5% of all strains). Single lysis with phage Ph13 was observed in 7 of the 14 patients (49% of all strains), in species S. capitis, S. epidermidis, S. haemolyticus, S. hominis, and S. warneri. In S. haemolyticus, non-typable strains predominated (66%); this character occurred only in 2% among other species. The strains colonizing the immunocompromised patients differed from each other in phage pattern, antibiotic resistance pattern, and/or slime production. No hospital infection was suggested. On the other hand, high incidence of two well-definable phage patterns raises some relationship between phage receptors or some regulatory systems in phage multiplication and factors responsible for special colonization as common surface properties.

Bacterial Typing Techniques↗
PubMed1985

Mechanisms of pattern generation underlying swimming in Tritonia. IV. Gating of central pattern generator.

Swimming behavior in the marine mollusc Tritonia diomedea is episodic, consisting of a series of alternating dorsal and ventral flexions initiated by a brief sensory stimulus. The swim motor pattern is generated by a network formed of four groups of premotor interneurons: cerebral cell 2 (C2), dorsal swim interneurons (DSIs), and two types of ventral swim interneurons (VSI-A and VSI-B). The initiation and maintenance of swimming depends on the establishment of a long-lasting ramp depolarization in both the premotor, pattern-generating interneurons, and the motor neurons (i.e., flexion neurons). Voltage clamp was used to measure the membrane current responsible for the ramp depolarization. In all cell classes the current had two components: a tonic inward current, which decayed as the swim progressed, and phasic inward current waves, which provided the synaptic drive during each swim burst. The ramp current in the flexion neurons and in C2 was generated largely by activity within the interneuronal pattern-generating network (PGN). The ramp current could be mimicked by driving activity in the pattern-generating interneurons. In VSI-B, the tonic component of the ramp current was independent of activity within the PGN and appeared to be derived from the long-lasting effect of an extrinsic input. The phasic components of the ramp, however, were dependent on PGN activity. The phasic inward current waves were blocked when pattern generation was prevented. In addition, phasic inward currents similar to those occurring during swimming could be produced by driving the C2. The tonic component of the ramp current in a DSI was dependent both on extrinsic inputs and PGN activity. Extrinsic inputs appeared to control the first 10-15 s of the tonic current. At longer times, activity within the DSI population itself maintained the ramp current. When one DSI was driven in a quiescent preparation, all other DSIs were inhibited, yet the DSIs are known to be coupled by monosynaptic, reciprocal excitatory synapses. This effect could be explained by the action of an unidentified inhibitory interneuron (I-neuron), which was excited by DSIs and in turn inhibited all other DSIs. The DSIs were therefore coupled reciprocally by both monosynaptic excitation and polysynaptic inhibition. Activity in C2 switched the DSI-DSI interaction from inhibition to excitation by inhibiting the I-neuron.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1986

Dermatoglyphic patterns and pattern intensities of Callicebus (primates: Cebidae): description and comparison of three species.

The palmar and plantar dermatoglyphic pattern types are described for three species of Callicebus (18 Callicebus moloch, 18 Callicebus torquatus and 7 Callicebus personatus). Mean pattern intensities (API) were calculated for each of seven areas of the palm and nine areas of the sole, and a summed mean total pattern intensity (TPI) for each volar surface. Nonparametric statistical testing showed no significant bilateral asymmetry or sexual dimorphism in pattern intensities. Pattern profiles describing the relative relationships of API values across the left palm and sole are presented. The profiles typical of the genus closely resemble those of Aotus and Saimiri. Significant interspecific differences, particularly in the plantar API values, were detected. The results are discussed with reference to the present taxonomic classification of the species of Callicebus and their postulated evolutionary history.

Animals↗
PubMed1989

[Chewing pattern in posterior crossbite. Classification of chewing pattern in the frontal plane].

Occlusion is one of the most important factors to affect chewing movement. In this study, chewing movements of subjects who have posterior crossbite were recorded to analyze the relationship between chewing pattern and crossbite occlusion. Chewing movements of 22 subjects of posterior crossbite and 5 normals were recorded with Sirognathograph Analysing System II. Subjects were to chew soft gum; on each specified side, both at the posterior crossbite region and at another resion of the side. On the other hand, normal subjects were to chew only on each side. Chewing patterns were classified into several specific ones examined with chisquare test concerning the relationship between chewing pattern and occlusion. From the results we obtained following conclusion. 1. Frequency of normal chewing pattern, posterior crossbite group is lower than normal group. 2. Among the posterior crossbite group, specific patterns are found with highly frequency such as 'Concave Type', 'Crossover I Type', 'Crossover II Type' and 'Reverse Type'. 3. By segmental chewing at the posterior crossbite region, 'Normal Type' and 'Concave Type' are lower and 'Crossover I Type', 'Crossover II Type' and 'Reverse Type' are higher in frequency in comparison with posterior crossbite side voluntary chewing. 4. By segmental chewing at the posterior crossbite resion, 'Normal Type' and 'Concave Type' are lower and 'Crossover I Type', 'Crossover II Type' and 'Reverse Type' are higher in frequency in comparison with segmental chewing at non-crossbite resion.

Humans↗
PubMedDate not supplied

Lung cancer patterns in Switzerland: a search for geographical and occupational patterns.

Simple descriptive methods (geographical correlation, variance and covariance analysis; gradients of mortality by quantiles; proportionate ratio methods) have been used to characterize the distribution patterns of lung cancer in Switzerland since 1969: Geographical patterns. In males, the temporo-spatial distribution of lung cancer mortality indicates that male smoking became prevalent earlier in the conurbations than in the countryside. The culturolinguistic gap between the German and French/Italian-speaking parts is mirrored by higher lung cancer rates in the latter. For female lung cancer the urban-rural gradient overshadows differences between the linguistic regions. Occupational patterns. The consistency of occupationally associated lung cancer risks within Switzerland is remarkable, even in small occupational groups with only a few deaths, and parallels the patterns known from international statistics. An analysis of lung cancer incidence within the Zurich cancer registry by histological types reveals the same consistent patterns with high risks in blue-collar trades.

Adolescent↗
PubMed1985

Independent development of homologous pattern elements in the wing patterns of butterflies.

Rank correlation analyses demonstrate that the degree of color pattern development in each wing cell of Cercyonis pegala (Satyridae) and Smyrna blomfildia (Nymphalidae) is either weakly or not at all correlated with that in other wing cells. There is much greater individual variability in pattern development in different wing cells than there is in homologous wing cells on opposite wings. This finding indicates that differences in pattern development in adjacent wing cells are not due to developmental noise, but are programmed, and that pattern development in each wing cell is in large measure independent of that in other wing cells.

Animals↗
PubMed1989

Respiratory patterns associated with swallowing: Part 1. The normal adult pattern and changes with age.

Simple, non-invasive equipment was designed to record respiratory patterns associated with swallowing food or drink in young and elderly healthy adults, to compare with neurologically impaired patients who complained of dysphagia. The timing of the entry of the test drink from a spoon into the mouth, the swallow event and respiration were recorded electronically and were presented in chart form. The equipment proved to be easy to use and the results were consistent. All 33 subjects showed a well-defined respiratory pattern, with individual minor variations, but different from the pattern of their resting respiration. The direction of respiration during spoon contact was consistent for each individual and the pharyngeal stage of swallowing was almost always followed by a large expiration. Thus the resting respiration is not simply arrested during swallowing, but is substituted by a different, well-controlled pattern.

Adult↗
PubMed1988

Pattern ERGs and VEP topography evoked by lateral eccentric pattern reversal stimulation.

In ten healthy subjects we recorded simultaneously pattern-ERGs and multichannel VEPs evoked by checkerboard reversal stimuli presented in the center, and at three different locations on the nasal and temporal retina. In the near periphery significantly larger pattern-ERG amplitudes were found for the nasal retina. Farther out in the periphery this effect reversed, and stimuli presented to the temporal retina yielded larger pattern-ERG amplitudes. Component latencies showed also differences with larger latencies for nasal than temporal retinal stimuli in the near periphery. In addition, pattern-ERG amplitudes increased with check size while peak latencies decreased. Retinal stimulus location had a significant influence on the VEP topography reflected by potential distributions lateralized over occipital scalp areas contralateral to the hemiretina stimulated. There were no differences between VEP activity evoked by nasal or temporal retinal stimuli. The results relate to differences in local retinal organization reflected by the distribution of photoreceptors and other neural elements across the retina as well as to functional differences in visual information processing between different retinal areas.

Adult↗
PubMed1992

[Linearity and nonlinearity of pattern ERG and pattern VECP].

To investigate the linearity and nonlinearity of both pattern electroretinogram (P-ERG) and pattern visually evoked cortical potential (P-VECP), a checkerboard pattern was presented to normal subjects with the reversal rate of transient and steady-state condition. Using a personal computer (BASIC) system, we made simulated waves (linear model) at 3 to 15 rev/s stimuli summated from an original wave evoked at 1 rev/s stimulation. Both simulated P-ERGs and P-VECPs were found to be different from the original ones, and the nonlinear component, which was interpreted as the difference between the original and simulated waves, was thought to increase with the increment of pattern reversal rate. However the 2 nd harmonic component of the original wave drastically decreased at above 7.5 rev/s stimulation. Thus, it is concluded that the nonlinearity of both P-ERG and P-VECP does not correlate with those 2 nd harmonic components.

Adult↗
PubMed1991

The "ladder light chain" or "pseudo-oligoclonal" pattern in urinary immunofixation electrophoresis (IFE) studies: a distinctive IFE pattern and an explanatory hypothesis relating it to free polyclonal light chains.

I previously reported the occurrence of a pattern of multiple, equally spaced, low-concentration light chain bands in urine in immunofixation electrophoresis (IFE) studies (Clin Chem 1990;36:1526-7). Although the pattern varies somewhat among patients with regard to the number of bands, light chain type, and concentration, it is relatively invariant with regard to the location and spacing of three prominent kappa bands. The regular spacing of these urinary light chain bands imparts a "ladder rung" or "pseudo-oligoclonal" appearance. High-resolution, two-dimensional electrophoresis of these urine specimens reveals a regularly spaced, isomassic, restricted zonal distribution in the light chain region. These findings may be explained as the results of expression of superfamilies of related, polyclonal, free light chains, which co-migrate because of the limited variety of amino acid substitutions allowed by recombination constraints on light chain genes. This urinary IFE phenomenon is called the ladder light chain (LLC) pattern or pseudo-oligoclonal free light chain pattern to avoid implications of origin from specific clonal proliferation.

Bence Jones Protein↗
PubMed1990

Relationship of early intrapartum fetal heart rate patterns to subsequent patterns and fetal outcome.

This study evaluated subsequent fetal heart rate (FHR) patterns and fetal outcome in laboring women with normal or abnormal initial FHR patterns. Four hundred term gravidas presenting in the latent phase of labor were studied. Ninety (22.5%) exhibited abnormalities on the initial tracing, with the majority of those abnormalities (58.9%) including mild variable decelerations, either alone or in combination with other abnormalities. An analysis of the outcome for those patients revealed a significant increase in cesarean delivery for fetal distress and depressed one-minute Apgar scores when compared to patients with initially normal tracings. Analysis of subsequent FHR patterns in that group showed a significant increase in the incidence of atypical variable declerations and bradycardia. Patients with more than one abnormality on the initial FHR tracing showed a greater incidence of loss of variability, loss of reactivity and bradycardia on subsequent FHR tracings. Likewise, pregnancy outcome for this group was remarkable for an increased risk of meconium staining, cesarean delivery for fetal distress and depressed one-minute Apgar scores. An abnormal initial FHR tracing seems to be associated with the subsequent development of ominous FHR patterns and increased fetal morbidity, particularly when more than one abnormality is present on the initial tracing.

Apgar Score↗
PubMed1989

Abnormality of the pattern electroretinogram and pattern visual evoked cortical response in esotropic cats.

In six 3-week-old kittens, the tendon of the lateral rectus muscle of one eye was sectioned under anaesthesia in order to induce an esotropic (nasally-directed) squint. At maturity, the pattern electroretinogram (PERG) and pattern visual evoked response (PVER) were recorded under anaesthesia to phase-reversal at 1.67 Hz of a 0.5c/deg square wave grating pattern of 75% contrast. Refraction was determined by retinoscopy and confirmed by recording the PERG for different trial lenses. The amplitude and time-to-peak of the PERG and PVER were compared between operated and unoperated eyes, and with the responses of one normal and two sham-operated cats. With stimulation of the operated eye, the amplitude of the PVER was consistently reduced by 50% compared with the non-operated eye, confirming that the cats had become amblyopic as a result of the squint. While the appreciable inter-eye variations in the amplitude of the PERG of the normal and sham-operated cats precluded identification of a change in the esotropic cats, there was a consistent prolongation of the time-to-peak of the PERG by 50% with stimulation of the operated eye. This result is consistent with a retinal component to strabismic amblyopia.

Amblyopia↗
PubMed1987

Effect of pattern luminance profile on the pattern ERG in man and pigeon.

Pattern electroretinograms (PERGs) have been recorded in man and pigeon using phase reversing patterns. Studies were made in both species of the effect of grating spatial frequency, grating profile (sine or square) or the size of the squares of a checkerboard on the amplitude of the responses. The results obtained in the two species were similar. In general, the ratio of the amplitudes of the sine wave:square wave responses is that predicted by the Fourier fundamentals of the pattern, and is thus not determined by changes in local luminance or contrast as it is normally defined. Checks however gave larger responses than sine or square wave profile bars matched to the Fourier fundamental on the diagonal. The results are not explicable in terms of any single stimulus parameter and suggest that the PERG generator has a degree of center/surround organisation similar to retinal ganglion cells. It is however argued that, because of the known physiological properties, generators cannot be unequivocally localised by varying the stimulus or comparing retinal, cortical and perceptual response dynamics.

Animals↗
PubMed1988

Representing and defining patterns by graphs: applications to sol-gel patterns and to cytoskeleton.

The problems of interdisciplinary interests--applying methods of graph theory to sol-gel patterns and to cytoskeleton--are discussed. The importance of sol-gel transition phenomena in living cells and the possibility of periodic sol-gel transition phenomena are briefly reviewed. Representing patterns by graphs and using graph probabilistic representation for calculating structure-property relationships are discussed and applied to sol-gel transition patterns.

Biometry↗