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PubMed1993

Perceptual processing of pattern goodness by left and right hemispheres.

Two experiments tested perceptual processing of Garner and Clement's (1963) good and poor five-dot patterns by the left and right hemispheres. Two (good) patterns were from four-member equivalence sets, and the other (poor) pattern was from an eight-member equivalence set. One of the good patterns formed a T shape that could be processed as a linguistic unit. In Experiment 1, 80 right-handed subjects made same-different judgments for lateralized 200-msec paired presentations of these patterns. When both presentations were to the RVF/LH, response latency was faster for the T pattern than for the other two. When both presentations were to the LVF/RH, response latency was faster for the two good patterns than for the poor pattern. When the first pattern was presented to the RVF/LH and the second was presented to the LVF/RH, response latencies were lower for the two good patterns than for the poor pattern. Also, when the first pattern was presented to the LVF/RH and the second was presented to the RVF/LH, response latency was faster for the T pattern than for the other good pattern which was, in turn, faster than for the poor pattern. Experiment 2 used a duration judgment task (Avant & Lyman, 1975) to test effects of pattern goodness on apparent durations of pre- and postmasked 10-msec pattern presentations. With left hemisphere inputs, presentations of good patterns were judged to be longer than presentations of the poor pattern. When each hemisphere compared the T and the other good pattern, presentations of the T pattern were judged to be longer, and the right hemisphere further discriminated among pattern orientations. Presentations of the T pattern to each hemisphere were judged to be longer than presentations of the poor pattern, and both hemispheres discriminated among orientations of both patterns. These results indicate that the two hemispheres can, during perceptual processing, function cooperatively, and that both prerecognition and conscious perceptual operations are guided by task demands.

Adult↗
PubMed1990

[A comparative study on proliferative activity in different histological patterns of adenoid cystic carcinoma--from a viewpoint of nuclear DNA contents].

Adenoid cystic carcinoma generally consists of the following histologic features: tubular, cribriform, trabecular, and solid. To investigate how these histological patterns affect the prognosis of this carcinoma, we determined the proliferative activity of each of the histologic patterns by cytofluorometry. Twenty-six cases of adenoid cystic carcinoma, obtained by surgical resection, were studied. According to predominant histological pattern, they were divided into three groups: seven cases were of cribriform pattern, nine cases of trabecular pattern, and ten cases of solid pattern. The region with each dominant pattern was obtained from biopsy specimen, and the nuclear DNA contents of the tumor cells of the regions were assayed. In four of twenty-six cases, that of the tumor cells of the region with other patterns in the same specimens were also assayed. The results were the following: 1) The mean incidence of over 4.5C-polyploid cells of the region with predominant pattern of each tumor significantly increased in the following order: cribriform pattern and solid pattern. 2) The incidence of over 4.5C-polyploid cells, in comparison of a predominant pattern with other histologic patterns in the same tumor, were calculated. It was higher in solid pattern than in trabecular pattern, and was higher in trabecular pattern than cribriform pattern. 3) Only two of ten cases, had aneuploidy in the region with predominant solid pattern and the other cases had diploid stem line. Judging from the above results, it was concluded that proliferative activity of each pattern increased in the following order: cribriform pattern, trabecular pattern, solid pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Hepatic lipase and lipoprotein lipase are not major determinants of the low density lipoprotein subclass pattern in human subjects with coronary heart disease.

The influence of hepatic lipase (HL) and lipoprotein lipase (LPL) activity on the low density lipoprotein (LDL) subclass pattern was studied in a population of males with coronary heart disease and without severe hypercholesterolemia. LDL subclass patterns, lipases and plasma lipoproteins were determined in 326 patients. In part of the study population, fasting insulin and glucose levels were also determined. The LDL subclass pattern was determined by gradient gel electrophoresis (GGE) and classified according to Austin et al. (J. Am. Med. Assoc. 260 (1988) 1917 (predominantly large LDL = A-pattern, predominantly small LDL = B-pattern). An LDL subclass A-pattern was exhibited by 199 subjects; 108 exhibited a B-pattern. In 19 subjects no distinctive A- or B-pattern was present (A/B-pattern). Hepatic and lipoprotein activities differed significantly between patients with the A- or B-pattern. The median hepatic lipase activity was lower (384 vs. 417 mU/ml, P = 0.006), and the lipoprotein lipase activity higher (122 vs. 101 mU/ml, P = 0.001) in the A-pattern subjects than in the B-pattern subjects. In subjects with the A/B pattern the lipase activities were intermediate between the values in the A- and B-pattern subjects (HL 408 +/- 87 mU/ml, LPL 115 +/- 55 mU/ml). Plasma triglyceride, very low density lipoprotein (VLDL)-triglyceride, intermediate density lipoprotein (IDL)-triglyceride and LDL-triglyceride were higher in the patients with a B-pattern (+84%, +171%, +10% and +16%, respectively). Total plasma cholesterol was not different between A- and B-pattern subjects. VLDL- and IDL-cholesterol were higher in the B-pattern group (+174% and +66%, respectively), while LDL- and HDL-cholesterol were higher in the A-pattern group (+2 and +24%, respectively). In univariate analysis HL, LPL, plasma (and VLDL) triglyceride, HDL-cholesterol and IDL-cholesterol were each significantly associated with the LDL subclass pattern. In multivariate analysis plasma triglyceride (or VLDL-triglyceride) and HDL-cholesterol appeared to be independently associated with the LDL subclass pattern. No additional discriminative value of HL or LPL was found. Similar results were obtained if the patients with or without beta blocker were evaluated separately. An estimate of insulin resistance (EIR), calculated from plasma insulin and glucose in part of the study population (n = 145), was significantly higher in the subjects with a B-pattern than in those with an A-pattern (3.12 vs. 2.00, P < 0.003). EIR correlated positively with plasma triglyceride (P < 0.0001), but not with HL or LPL.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1973

Analysis of perception of complex visual stimulus-patterns.

This paper deals with the analysis of visual perceptions of complex patterns consisting of two simple patterns placed one above the other in one frame (united pattern) or in two separate frames each (divided pattern). The upper pattern consisted of a configuration of lines, the lower one of a configuration of dots. There were one positive pattern which a subject had to recognize in tachistoscopic exposure and a number of negative patterns which a subject had to reject. When the dot component of the positive pattern consisted of two dots situated near its left edge, the subjects committed a great number of errors in recognition of the positive pattern and also the negative patterns with dot-negative components. Errors in recognition of negative patterns with line-negative components were much less numerous. Generally less errors were committed with divided patterns than with united patterns. When in the dot component of the positive pattern the distance between the dots was increased and they were placed symmetrically, the number of errors in recognition of this pattern decreased considerably; errors made in rejecting the negative patterns were, however, the same as in the previous test. Contrary to the previous test, errors with united patterns were less numerous than with divided patterns. The data obtained are discussed with reference to the concept of lateral inhibition between components of the complex unknown patterns. It is postulated that this inhibition can be partially overcome if the components of the complex pattern are easy integrated as is the case with symmetric united patterns.

Analysis of Variance↗
PubMed2000

Histological pattern of mandibular invasion by oral squamous cell carcinoma.

OBJECTIVE: Mandibular invasion by oral squamous cell carcinoma may progress by either an infiltrative or an erosive histological pattern. The infiltrative pattern is marked by nests and cords of tumor cells along an irregular tumor front, and the erosive pattern exhibits a broad, pushing tumor front. The objectives of this study were 1) to define the characteristics associated with each histological pattern of mandibular invasion, 2) to assess the relationship between pattern of invasion and clinical outcome as measured by death with disease and disease presence at last follow-up, and 3) to determine whether the cell cycle markers cyclin D1 and Ki-67 are associated with the histological pattern of invasion or are predictive of outcome. STUDY DESIGN: Retrospective study of 68 patients with mandibular invasion by oral cavity squamous cell carcinoma treated by mandibulectomy. METHODS: The clinical records, pathology reports, and original H&E-stained slides were reviewed for each patient. Immunohistochemical staining of cyclin D1 and Ki-67 was performed on slides cut from the paraffin blocks of these patients' specimens. RESULTS: The parameters found to be significantly associated with the infiltrative pattern of mandibular invasion included higher tumor grade, medullary space invasion, positive bone or soft tissue margins, history of previously failed treatment, and postoperative tumor recurrence. The infiltrative pattern had a positive bone margin rate of 47.6% and a primary site recurrence rate of 52.6%. In contrast, the erosive pattern had a positive bone margin rate of 4.9% and a primary site recurrence rate of 16.7%. The infiltrative pattern of invasion gave a fourfold increased risk of death with disease and disease presence at last follow-up in univariate and multivariate analyses when compared with the erosive pattern of invasion. The 3-year disease-free survival was 30% for the infiltrative pattern and 73% for the erosive pattern. The median disease-free survival was 1.5 years for the infiltrative pattern and 5.5 years for the erosive pattern. There was no correlation between cyclin D1 or Ki-67 staining and invasion pattern or clinical outcome. CONCLUSIONS: The infiltrative pattern of mandibular invasion by oral squamous cell carcinoma is correlated with a significantly worse prognosis when compared with the erosive pattern of invasion. The infiltrative pattern clearly exhibits a more aggressive behavior with an increased likelihood of positive margins, recurrence, death with disease, and shorter disease-free survival. We recommend that pathologists routinely comment on the histological pattern of invasion when reviewing oral squamous cell carcinoma with mandibular invasion.

Adult↗
PubMed1979

Patterns of haemodynamic alteration during left ventricular ischaemia in man. Relation to angiographic extent of coronary artery disease.

Haemodynamic changes produced by rapid atrial pacing (60 patients, 52 of whom developed angina) or in association with spontaneous angina (32 patients) were measured in 92 patients with angiographic coronary artery disease. The extent of coronary artery disease was scored by the jeopardy score system (range 0 to 12). The haemodynamic changes induced by ischaemia occurred in 3 patterns: pattern I, no change in filling pressure or in mean systemic arterial pressure; pattern II, a rise in filling pressure and a rise in mean systemic arterial pressure; pattern III, a rise in filling pressure, but no significant change or a fall in mean systemic arterial pressure. In patients who had a pattern II or a pattern III response to ischaemia, the change in mean systemic arterial pressure was linearly related to the corresponding change in cardiac output. The likelihood of a patient showing a given pattern of ischaemia-induced haemodynamic change was related to the extent of coronary artery disease; of 22 patients with jeopardy scores of 2 or 4, 91% exhibited pattern I, 9% pattern II, and none pattern III; of 39 patients with jeopardy scores of 6 or 8, 40% exhibited pattern I, 22% pattern II, and 38% pattern III; of 31 patients with jeopardy scores of 10 or 12, 12% exhibited pattern I, 10% pattern II, and 78% pattern III (P less than 0.01). Among the 54 patients in whom serial cardiac output determinations were available, a decline of the left ventricular function curve during ischaemia was demonstrable in 8% of those with a pattern I response, in 54% of those with a pattern II response, and in 90% of those with a pattern III response (P less than 0.01). The pattern of response was unrelated to resting angiographic left ventricular ejection fraction, whether ST segments became elevated or depressed, or whether ischaemia was pacing-induced or spontaneous. These results suggest that the haemodynamic response to ischaemia is determined by the fraction of the left ventricle that becomes dysfunctional during ischaemia.

Blood Pressure↗
PubMed1983

Electroretinograms evoked in man by local uniform or patterned stimulation.

1. We have recorded electroretinograms (e.r.g.s) in normal subjects. Television monitors were used as stimulators. The screens were surrounded by brightly lit white reflecting surfaces to ensure that the responses were developed by defined retinal areas.2. Various types of stimuli were employed. Either (i) a pattern of dark and bright squares was reversed, to evoke a pattern e.r.g. (p.e.r.g.), (ii) the luminance of the uniform screen was abruptly increased and decreased to evoke a focal on-off e.r.g. or (iii) a pattern was made to appear and disappear from a uniform background. In each of these cases, the sequence of changes of luminance at any one point could be made identical. The aim of the experiments was to determine whether the e.r.g. was modified by the spatial organization of the stimulus.3. In other experiments a colour monitor was used so that (i) a red-green flicker, (ii) red-green pattern reversal or (iii) the appearance of a red-green pattern from a yellow background could be used as a stimulus. The responses were caused by the changes in hue, since all the colours were equiluminant.4. With black and white patterns the p.e.r.g. peaks 5 msec later than the focal on-off e.r.g. The largest response is produced by squares of 0.5-1 degrees subtense.5. The ratio of the amplitudes of the p.e.r.g. to the focal on-off response is largest for stimuli confined to the macula and smallest for those projected onto peripheral retina.6. The amplitude of responses to chequerboard reversing patterns increases nearly linearly with contrast up to the maximum contrast available.7. When patterns appear or disappear from a uniform screen, and there is an associated change in the quantity of light entering the eye, recognizable b-waves occur when the average screen luminance increases, independently of whether pattern contrast increases (appearance) or decreases (disappearance).8. When a pattern appears or disappears with no change in luminance, e.r.g.s are evoked at both ;on' and ;off'. The disappearance of the dark parts of the pattern causes the largest logarithmic increase in local retinal illumination. For patterns of square size > 4 degrees the pattern disappearance response is larger than for pattern appearance. As the square size is reduced, the appearance response grows and the disappearance response decreases. The e.r.g.s evoked by the appropriate changes in luminance of a uniform screen are no longer the same as those caused by the appearance and disappearance of the pattern.9. The responses to change of hue are 70% as large as those produced by black and white patterns. The same ratio occurs for pattern and focal on-off e.r.g.s.10. When coloured patterns appear from and disappear to a uniform field, the e.r.g.s. evoked are very similar to those recorded when the appropriate changes of hue occur in a uniform field. This result is quite different to the findings for black and white patterns (see 8 above).11. The results suggest that it is the change in local adaptation caused by the black and white patterns which modifies the e.r.g. and not the presence of contrasting borders.

Color Perception↗
PubMed1999

An in vitro comparison of the effect of number and pattern of positional screws on load resistance.

OBJECTIVE: The purpose of this in vitro investigation was to determine whether the number or pattern of placement of positional screws affected their ability to resist vertical loads resembling mastication. MATERIALS AND METHODS: Standardized bone substitutes were secured with varying numbers of 17.0-mm-long, 2.0-mm outer diameter, self-tapping titanium screws (W. Lorenz Surgical, Jacksonville, FL) in various patterns using a positional screw technique. These patterns included one, two, three, four, and five screws in a linear pattern; two screws in a vertical pattern; three screws in an L-pattern, inverted-L pattern, backward-L pattern, inverted-backward-L pattern, and right and left diagonal pattern; four screws in a box pattern; and five screws in a domino pattern. Five models of each group were fabricated along with a control group. The models were secured in a jig and subjected to vertical loads by an Instron 8511.20 Mechanical Testing Unit (Canton, MA) until failure. Common engineering standards, including yield load, yield displacement, stiffness, maximum load, and displacement at maximum load, were measured, and means and standard deviations were derived and compared for statistical significance with an analysis of variance (ANOVA) and Scheffe multiple comparison test. RESULTS: Screw number and pattern of placement affected the mechanical characteristics in resistance to vertical load. Screw numbers less than three and all linear patterns were the least effective. The three-screw L patterns, as a category, provided greater resistance to vertical loads than either the three-screw linear or three-screw diagonal patterns. The addition of more than three screws in geometric patterns offered no greater benefit than the three-screw L patterns. CONCLUSIONS: In this in vitro study, the three-screw L patterns were the most effective and efficient when using the positional screw technique.

Analysis of Variance↗
PubMed1980

Patterns of factor-VIII related antigen on crossed immunoelectrophoresis and large pore polyacrylamide gel-crossed immunoelectrophoresis in von Willebrand's disease.

Plasma samples from patients with various types of von Willebrand's disease were subdivided into six patterns according to the electrophoretic mobility and shape of VIIIR: Ag on crossed immunoelectrophoresis (CIE): pattern 1 no precipitation are, pattern 2 normal mobility with low arc, arc, pattern 3 intermediate mobility with low arc, pattern 4 faster anodal mobility with low arc, pattern 5 normal mobility with normal are height, pattern 6 faster anodal mobility with normal are height. Of 62 patients, 14 had pattern 1, 6 pattern 2, 16 pattern 3, 12 pattern 4, 9 pattern 5, and 5 pattern 6. Large pore polyacrylamide-agarose gel-crossed immunoelectrophoresis (PAAG-CIE) of crude factor VIII fraction from cryoprecipitate revealed no arcs in patients with pattern 1, three arcs of reduced height in the patients with patterns 2 and 3, four arcs very similar to normal control in patients with pattern 5, and two arcs with fast anodal migration in the patients with patterns 4 and 6. Crude factor VIII fractions from normal cryosupernatant showed one low fast anodally migrating arc corresponding to the fourth arc of normal cryoprecipitate. No peak was seen in patients with pattern 1, and one low fast anodal arc similar to normal control was present in the patients with patterns 2, 3, 4, 5 and 6.

Antigens↗
PubMed2000

Precise spatiotemporal repeating patterns in monkey primary and supplementary motor areas occur at chance levels.

Precise spatiotemporal patterns in neural discharge are a possible mechanism for information encoding in the brain. Previous studies have found that such patterns repeat and appear to relate to key behavioral events. Whether these patterns occur above chance levels remains controversial. To address this question, we have made simultaneous recordings from between two and nine neurons in the primary motor cortex and supplementary motor area of three monkeys while they performed a precision grip task. Out of a total of 67 neurons, 46 were antidromically identified as pyramidal tract neurons. Sections of recordings 60 s long were searched for patterns involving three or more spikes that repeated at least twice. The allowed jitter for pattern repetition was 3 ms, and the pattern length was limited to 192 ms. In all 11 recordings analyzed, large numbers of repeating patterns were found. To assess the expected chance level of patterns, "surrogate" datasets were generated. These had the same moment-by-moment modulation in firing rate as the experimental spike trains, and matched their interspike interval distribution, but did not preserve the precise timing of individual spikes. The number of repeating patterns in 10 randomly generated surrogates was used to form 99% confidence limits on the repeating pattern count expected by chance. There was close agreement between these confidence limits and the number of patterns seen in the experimental data. Analysis of high complexity patterns was carried out in four long recordings (mean duration 23.2 min, mean number of neurons simultaneously recorded 7.5). This analysis logged only patterns composed of a larger number (7-11) of spikes. The number of patterns seen in the surrogate datasets showed a small but significant excess over those seen in the original experimental data; this is discussed in the context of surrogate generation. The occurrence of repeating patterns in the experimental data were strongly associated with particular phases of the precision grip task; however, a similar task dependence was seen for the surrogate data. When a repeating pattern was used as a template to find inexact matches, in which up to half of the component spikes could be missing, similar numbers of matches were found in experimental and surrogate data, and the time of occurrence of such matches showed the same task dependence. We conclude that the existence of precise repeating patterns in our data are not due to cortical mechanisms that favor this form of coding, since as many, if not more, patterns are produced by spike trains constructed only to modulate their firing rate in the same way as the experimental data, and to match the interspike interval histograms. The task dependence of pattern occurrence is explicable as an artifact of the modulation of neural firing rate. The consequences for theories of temporal coding in the cortex are discussed.

Action Potentials↗
PubMed2002

Identification of scanned and static tactile patterns.

Most of the studies in which the interactions between target and nontarget spatial patterns have been examined have tested patterns that are generated statically. Static patterns are those in which all the elements of the pattern are presented at the same time and at a fixed location on the skin; however, most tactile information comes to the skin by means of patterns' being scanned across the surface of the skin. In the present study, the interactions between target and nontarget patterns were measured for patterns generated in both the static and the scanned modes. Nontarget patterns often interfere with the perception of target patterns. Using patterns generated in the static mode, previous studies have identified two factors that produce interference in pattern identification: response competition and masking. Masking, in turn, appears to be the result of temporal integration of the target and nontarget patterns, as well as the displacement of target features. In the present study, these factors were examined for patterns generated in both static and scanned modes. Regardless of the mode in which the patterns were generated, similar functions were obtained relating identification performance to the temporal separation between the target and the nontarget patterns. Although statically generated patterns are more easily identified than scanned patterns, particularly at brief durations, mechanisms such as response competition, temporal integration, and the displacement of target features appear to be factors that affect scanned patterns to nearly the same degree as static patterns.

Adult↗
PubMed1985

Perception of symmetry in infancy: the salience of vertical symmetry and the perception of pattern wholes.

Four experiments were conducted to assess converging aspects of 4-month-old infants' perception of symmetry in visual patterns. Experiments 1 and 2 manipulated the structure and orientation of comparable patterns in order to evaluate the specialty of vertical symmetry. Infants showed no preference among vertically symmetrical, vertically repeated, and obliquely symmetrical patterns, but they processed vertically symmetrical patterns more efficiently than either vertically repeated patterns or obliquely symmetrical patterns. Experiment 3 manipulated the spatial separation of pattern components in order to determine the ability of young infants to integrate and coalesce information in visual patterns that is distributed in space. Infants processed vertically symmetrical patterns whose components were contiguous or nearly contiguous about the vertical axis (0 to 2.5 degrees separations) more efficiently than discontiguous patterns (5 and 10 degrees separations). Thus, extreme spatial separation about the vertical meridian caused infants to lose the advantage for vertical symmetry, and by inference their holistic perception of the visual pattern. Experiment 4 manipulated the organization of individual components of a vertical pattern in order to examine further infants' sensitivity to perceptual organization and synthesis of pattern form. Infants discriminated vertically symmetrical patterns from asymmetrical patterns with a vertical organization, thereby demonstrating sensitivity to the symmetrical organization of the pattern above their perception of components in the pattern. The results of these four experiments together corroborate and extend previous findings that vertical symmetry has a special status in early perceptual development and that infants can perceive pattern wholes.

Female↗
PubMed1986

[Glaucoma perimetry--optimization of test point patterns with an information index].

An experimental clinical study on 274 glaucomatous eyes was performed to investigate extensively the relation between test point patterns and information in glaucoma. We used the Humphrey Field Analyzer 620 and a special high-density pattern of 165 points containing all classic patterns of threshold perimetry (31, 32, 61). By deleting points the classic patterns, as well as other patterns, were deduced and compared. Using objective criteria, we measured the frequency of scotoma detection, modification, and refinement that occurred with pattern condensation in different areas. The average gain of information by new points, expressed by an information index, showed an exponential decrease with increasing spatial resolution. Also, the information index decreased toward the periphery for the same step. Optimal patterns, which have an equilibrated information index in all areas, should be denser in the center and coarser at the periphery. Two of these, a 3 degrees-4.2 degrees-6 degrees pattern (called "30-S") and a 4.2 degrees-6 degrees-8.5 degrees pattern ("half 30-S") were compared to the classic patterns and appeared to be superior, best demonstrable in the detection rate: each of the classic patterns (31, 32) missed 15% of the early glaucomatous defects, the adequate central condensed pattern only half of this. In the combination the classic patterns still missed 2.5% of the early defects; the corresponding central condensed pattern missed none. Moreover, these central condensed patterns have fewer points, so that test time is shorter. Changing to these patterns during follow-up is no problem, because this new family of test patterns is deduced from the classic patterns and corresponds in the majority of test locations.

Glaucoma↗
PubMed1997

Echocardiographic assessment of patent ductus arteriosus shunt flow pattern in premature infants.

AIMS: To identify the patent ductus arteriosus (PDA) shunt flow pattern using Doppler echocardiography; and to assess whether it could be used to predict the development of clinically significant PDA. METHODS: Premature infants weighing under 1500 g, who required mechanical ventilation, and in whom daily echocardiography could be performed from day 1 until the ductus closed, and on day 7 to confirm closure, were studied. The PDA shunt flow was identified from four Doppler patterns, and the closed pattern of a closed duct was also presented. Clinically significant PDA was diagnosed when there was colour Doppler echocardiographic evidence of left to right ductal shunt associated with at least two of the following clinical signs: heart murmur (systolic or continuous); persistent tachycardia (heart rate > 160/min); hyperactive precordial pulsation; bounding pulses; and radiographic evidence of cardiomegaly or pulmonary congestion. RESULTS: Of 68 infants enrolled into this study, clinically significant PDA developed in 31. The most recordable sequence of transition change of shunt flow pattern for clinically significant PDA was: pulmonary hypertension pattern, to growing pattern, to pulsatile pattern, to closing pattern, to closed pattern. And that for non-clinically significant PDA was: pulmonary hypertension pattern, to closing pattern, to closed pattern. The growing and the pulsatile patterns were mostly documented in infants with clinically significant PDA. The first documented growing pattern to predict clinically significant PDA gave a sensitivity of 64.5% and a specificity of 81.1%; the first documented pulsatile pattern gave a sensitivity of 93.5% and a specificity of 100%. CONCLUSION: Doppler echocardiographic assessment of PDA shunt flow pattern during the first 4 days of life is useful for predicting the development of clinically significant PDA in premature infants. At that stage, the closing or closed Doppler pattern indicates that infants are not at risk of developing clinically significant PDA; the growing or pulsatile Doppler pattern indicates a continuing risk of developing clinically significant PDA.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1983

Pattern-evoked responses and luminance-evoked responses in the human electroretinogram.

Electrical potentials were recorded from the cornea of the human eye in response to the onset and offset of square-wave stripe patterns varying in spatial frequency, luminance and contrast. Under high retinal illumination (50119 photopic td) the response to pattern onset was a positive wave (pattern-onset wave) followed by a negative after-potential. As long as the pattern was presented, a steady potential of positive polarity (plateau potential) was observed. The response to pattern offset was a biphasic negative-positive wave followed by a negative after-potential. A comparison between wave forms obtained with pattern onset-offset stimuli and luminance increase-decrease stimuli suggests: (a) the pattern-onset wave is the result of an interaction between a luminance-increase and a luminance-decrease response; (b) the plateau potential is mainly an additive superposition of two receptor processes originating from retinal areas that receive increases and decreases in local luminance; (c) the negative-positive potential is an a-wave and a b-wave originating from retinal areas that receive increases in local luminance. The amplitude of the pattern-onset wave was greatest at a spatial frequency around 3-4 c/deg. This behaviour was closely correlated with contrast sensitivity determined psychophysically by previous investigators. Therefore, the pattern-onset wave seems to be a pattern-evoked response. The amplitude of the b-wave following pattern offset showed a monotonic decrease with increasing spatial frequency. It is mainly a luminance-evoked response. Under low retinal illumination (457 photopic td) the pattern-onset wave and the b-wave at pattern offset were smaller. However, the pattern-onset wave had its maximum amplitude at a lower spatial frequency. When increases or decreases in space-average luminance were combined with pattern onset or offset, transitions between pattern- and luminance-evoked responses could be observed. The results suggest that a decrease in local luminance is the essential stimulus for evoking a pattern-related response while increases in local light intensity generate luminance-evoked responses.

Cornea↗
PubMed1995

Binary patterning of polar and nonpolar amino acids in the sequences and structures of native proteins.

Protein sequences can be represented as binary patterns of polar ([symbol: see text]) and nonpolar ([symbol: see text]) amino acids. These binary sequence patterns are categorized into two classes: Class A patterns match the structural repeat of an idealized amphiphilic alpha-helix (3.6 residues per turn), and class B patterns match the structural repeat of an idealized amphiphilic beta-strand (2 residues per turn). The difference between these two classes of sequence patterns has led to a strategy for de novo protein design based on binary patterning of polar and nonpolar amino acids. Here we ask whether similar binary patterning is incorporated in the sequences and structures of natural proteins. Analysis of the Protein Data Bank demonstrates the following. (1) Class A sequence patterns occur considerably more frequently in the sequences of natural proteins that would be expected at random, but class B patterns occur less often than expected. (2) Each pattern is found predominantly in the secondary structure expected from the binary strategy for protein design. Thus, class A patterns are found more frequently in alpha-helices than in beta-strands, and class B patterns are found more frequently in beta-strands than in alpha-helices. (3) Among the alpha-helices of natural proteins, the most commonly used binary patterns are indeed the class A patterns. (4) Among all beta-strands in the database, the most commonly used binary patterns are not the expected class B patterns. (5) However, for solvent-exposed beta-strands, the correlation is striking: All beta-strands in the database that contain the class B patterns are exposed to solvent.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1998

Different patterns of technetium-99m sestamibi uptake in multiple myeloma.

Technetium-99m 2-methoxyisobutylisonitrile (99mTc-MIBI) has been proposed as a potential tracer in patients with multiple myeloma (MM). The aims of this study were to evaluate the incidence of various patterns of diffuse 99mTc-MIBI uptake in patients with MM, to assess their relationship with clinical status and stage of disease, and to try to clarify the meaning of the diffuse bone marrow uptake of 99mTc-MIBI. Thirty-nine consecutive patients with MM were studied. Twenty-nine of these patients had active disease (13 in stage I, ten in stage II, and six in stage III) and ten were in remission after chemotherapy. Anterior and posterior whole-body scans were obtained 10 min after i.v. injection of 555 MBq of 99mTc-MIBI. The scans were classified as showing: pattern N, when only physiological uptake was present; pattern D, when diffuse bone marrow uptake was observed; pattern F, when areas of focal uptake of the radiotracer were evident; or pattern D+F, when both D and F patterns were observed. Diffuse bone marrow uptake was scored according to extension and intensity. Seven of the 39 patients (18%) showed pattern N, 18 (46%) pattern D, 2 (5%) pattern F, and 12 (31%) pattern D+F. Of the 32 patients with a positive 99mTc-MIBI scan (i.e. showing pattern D, F or D+F), 29 (91%) had active disease. Only three patients in remission showed pattern D, but with a very low bone marrow uptake score. Both extension and intensity of diffuse bone marrow uptake correlated with the amount of the monoclonal component and the percentage of bone marrow plasma cells. The distribution of the 99mTc-MIBI uptake patterns differed among patients in different stages of disease. Using as criteria for advanced stage the presence of either focal uptake (pattern F or D+F) or pattern D with a high score, high (90%) diagnostic accuracy was obtained. In conclusion, the patterns of 99mTc-MIBI uptake in patients with MM are related to both the clinical status and the stage of disease. The presence of focal uptake or of intense diffuse bone marrow uptake suggests that the patient has active and advanced stage disease, while a negative scan in a patient with MM clearly indicates remission.

Antibodies, Monoclonal↗
PubMed2003

Zebrafish puma mutant decouples pigment pattern and somatic metamorphosis.

The genetic and developmental bases for trait expression and variation in adults are largely unknown. One system in which genes and cell behaviors underlying adult traits can be elucidated is the larval-to-adult transformation of zebrafish, Danio rerio. Metamorphosis in this and many other teleost fishes resembles amphibian metamorphosis, as a variety of larval traits (e.g., fins, skin, digestive tract, sensory systems) are remodeled in a coordinated manner to generate the adult form. Among these traits is the pigment pattern, which comprises several neural crest-derived pigment cell classes, including black melanophores, yellow xanthophores, and iridescent iridophores. D. rerio embryos and early larvae exhibit a relatively simple pattern of melanophore stripes, but this pattern is transformed during metamorphosis into the more complex pattern of the adult, consisting of alternating dark (melanophore, iridophore) and light (xanthophore, iridophore) horizontal stripes. While it is clear that some pigment cells differentiate de novo during pigment pattern metamorphosis, the extent to which larval and adult pigment patterns are developmentally independent has not been known. In this study, we show that a subset of embryonic/early larval melanophores persists into adult stages in wild-type fish; thus, larval and adult pigment patterns are not completely independent in this species. We also analyze puma mutant zebrafish, derived from a forward genetic screen to isolate mutations affecting postembryonic development. In puma mutants, a wild-type embryonic/early larval pigment pattern forms, but supernumerary early larval melanophores persist in ectopic locations through juvenile and adult stages. We then show that, although puma mutants undergo a somatic metamorphosis at the same time as wild-type fish, metamorphic melanophores that normally appear during these stages are absent. The puma mutation thus decouples metamorphosis of the pigment pattern from the metamorphosis of many other traits. Nevertheless, puma mutants ultimately recover large numbers of melanophores and exhibit extensive pattern regulation during juvenile development, when the wild-type pigment pattern already would be completed. Finally, we demonstrate that the puma mutant is both temperature-sensitive and growth-sensitive: extremely severe pigment pattern defects result at a high temperature, a high growth rate, or both; whereas a wild-type pigment pattern can be rescued at a low temperature and a low growth rate. Taken together, these results provide new insights into zebrafish pigment pattern metamorphosis and the capacity for pattern regulation when normal patterning mechanisms go awry.

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