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Differential effects of nicotinic acid in subjects with different LDL subclass patterns.

Twenty-six subjects (20 male, 6 female) at high risk for CAD events were treated with moderate doses of nicotinic acid to investigate whether there was a differential lipoprotein response in patients with different LDL subclass patterns. Subjects were selected to have either pattern A (predominance of large LDL, peak particle diameter greater than 262 A, n = 9) or pattern B (predominance of small LDL, peak particle diameter less than 255 A, n = 17) as assessed by 2-16% gradient gel electrophoresis of plasma. Nicotinic acid dose was similar in pattern A (2111 +/- 651 mg/day) and pattern B subjects (1875 +/- 698 mg/day). Total cholesterol and LDL cholesterol decreased by similar amounts in pattern A (-41 +/- 26 mg/dl and -37 +/- 18 mg/dl) and pattern B (-51 +/- 44 mg/dl and -44 +/- 45 mg/dl) subjects. Triglycerides tended to be reduced more in pattern B subjects (-100 +/- 175 mg/dl) compared to pattern A subjects (-23 +/- 34 mg/dl) although this difference was not statistically significant (P = 0.08 for triglycerides log transformed). HDL cholesterol increased significantly more in the pattern B group (11.9 +/- 14.2 mg/dl) compared to pattern A subjects (0.7 +/- 8.5 mg/dl), (P less than 0.04). Similarly, LDL particle diameter increased significantly more in the pattern B subjects (9.8 +/- 6.9 A) compared to the pattern A subjects (3.6 +/- 3.0 A), (P less than 0.02). All pattern B subjects who achieved a plasma triglyceride less than 140 mg/dl converted to pattern A.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol↗

Prognostic significance of an interface pattern of central fibrosis and tumor cells in peripheral adenocarcinoma of the lung.

Fifty-nine surgically resected pulmonary adenocarcinomas were histologically classified into four types (A, B, C, and D) according to the pattern of invasion, ie, the extent of invasive tumor cell growth in the interface zone between alveoli replaced by cancer cells and the central region of fibrosis (so-called "scar"). In pattern A cancer cells proliferate along the alveolar walls without forming a frankly invasive lesion. In pattern B invasive lesions occupy less than 30% and in pattern C more than 30% of the fibrosing area. Pattern D refers to invasion of the bronchial lumen by cancer cells. The 59 tumors included 14 of pattern A, 12 of pattern B, 16 of pattern C, and 17 of pattern D. The 5-year survival rate for patients with pattern A tumors was 100%, and the rates for patients with pattern B, C, and D tumors were 64.2%, 30.0%, and 11.8%, respectively. Each difference between pairs of survival curves was statistically significant (P < .05). We found a correlation between the pattern of invasion and other prognostic factors. However, even in the cases evaluated as favorable by other prognostic factors (stage I, tumor less than 35 mm in diameter, negative for lymph node metastases, well-differentiated histology, negative for subpleural invasion, negative for vascular invasion) the survival curves became steeper going from pattern A to patterns B, C, and D. We conclude that the pattern of invasion is correlated with the prognosis of surgically treated patients. Our study may provide new histological criteria for the prognostic evaluation of pulmonary adenocarcinoma.

Adenocarcinoma↗

Stroke pattern and handrim biomechanics for level and uphill wheelchair propulsion at self-selected speeds.

OBJECTIVES: To investigate the natural stroke patterns of wheelchair users pushing on a level surface, to determine if users adapt their stroke patterns for pushing uphill, and to assess whether there are biomechanic advantages to one or more of the stroke patterns. DESIGN: Case series. SETTING: Biomechanics laboratory. PARTICIPANTS: Twenty-six manual wheelchair users with a spinal cord injury. INTERVENTION: Subjects pushed their own wheelchairs at self-selected speeds on a research treadmill set to level, 3 degrees , and 6 degrees grades. Stroke patterns were measured using a motion capture system. Handrim biomechanics were measured using an instrumented wheel. MAIN OUTCOME MEASURES: Stroke patterns were classified for both level and uphill propulsion according to 1 of 4 common classifications: arcing, semi-circular, single-looping (SLOP), and double-looping (DLOP). Biomechanic outcomes of speed, peak handrim force, cadence, and push angle were all compared across stroke classifications using an analysis of variance. RESULTS: Only 3 of the 4 stroke patterns were observed. None of the subjects used the semi-circular pattern. For level propulsion, the stroke patterns were fairly balanced between arcing (42%), SLOP (31%), and DLOP (27%). Subjects tended to change their stroke pattern for pushing uphill, with 73% of the subjects choosing the arcing pattern by the 6 degrees grade. No statistically significant differences were found in handrim biomechanics or subject characteristics across stroke pattern groups. CONCLUSIONS: Wheelchair users likely adapt their stroke pattern to accommodate their propulsion environment. Based on the large percentage of subjects who adopted the arcing pattern for pushing uphill, there may be benefits to the arcing pattern for pushing uphill. In light of this and other recent work, it is recommended that clinicians not instruct users to utilize a single stroke pattern in their everyday propulsion environments.

Acceleration↗

Hepatic vein flow pattern in children: assesment with Doppler sonography.

BACKGROUND: Aim of this study is to establish normal hepatic vein flow pattern and effect of age, sex, activity and feeding status on the hepatic flow pattern in normal Turkish children less than 15 years of ages and also to compare our values with the previously reported studies. METHOD: Hepatic vein flow patterns were evaluated in 150 children (83 male, 67 female) without any cardiac, pulmonary and liver disease by using Doppler sonography. Blood flow patterns were compared with age, sex, activity, and feeding status of the children. RESULTS: Only 44% of the children had triphasic flow pattern in all hepatic veins. Monophasic flow pattern was the most common flow pattern in children less then 1 year of age. Triphasic flow pattern increase after 1 year of age. Although most of the children older than 1 year of age had triphasic flow pattern, there is some variation in the flow patterns of the hepatic veins in the same subject. Triphasic hepatic flow pattern is most commonly seen in the left hepatic vein and least commonly seen in the right hepatic vein. There was no significant difference between male and girl, children who were agitated or calm and fasting or not fasting in respect to triphasic flow pattern. CONCLUSION: Liver stiffening is not only the reason for abnormal hepatic flow pattern and some other physiologic factors may also lead to mono and/or diphasic flow pattern in the children. Absence of triphasic flow pattern must not be accepted as a liver pathology in children especially younger than 1 year of age.

Adolescent↗

Two sinusoidal heart rate patterns in fetal lambs undergoing extracorporeal membrane oxygenation.

OBJECTIVES: The study analyzed the phase relationship between fetal heart rate and arterial blood pressure fluctuation during sinusoidal heart rate patterns in fetal lambs. STUDY DESIGN: Thirty-two fetal lambs were placed on extracorporeal membrane oxygenation after cesarean delivery at ages ranging between 113 and 133 days' gestation. Sinusoidal heart rate patterns persisting for >10 minutes were analyzed. The relationships between the sinusoidal heart rate cycles and the arterial blood pressure cycles were quantitatively expressed in degrees by timing the zenith and the nadir of each and assigning a phase-angle index (with 0 [360] and 180 degrees being synchronized and reciprocal, respectively). Simultaneous blood samples were taken from the 4 different sites of the fetal circulation for blood gas and acid-base analysis when the sinusoidal heart rate pattern appeared. Regional cerebral blood flow was determined by means of the colored microsphere technique in 8 fetuses with sinusoidal patterns and 7 control fetuses. RESULTS: Sinusoidal heart rate patterns were observed in 13 (40.6%) of the 32 fetal lambs. Two types of fetal heart rate and arterial blood pressure relationship could be recognized during sinusoidal pattern, the reciprocal type (n = 7) and the synchronized type (n = 9). A reciprocal type of sinusoidal pattern preceded a synchronized type pattern in 3 lambs that showed sinusoidal patterns at different stages of the experiment. The reciprocal type was associated with a higher baseline heart rate and amplitude of the sinusoidal heart rate pattern than was the synchronized type. The synchronized type was associated with a lower pH and base excess than was the reciprocal type. The cerebral blood flow in the medulla oblongata was significantly lower during the synchronized type pattern than during the reciprocal type pattern. CONCLUSION: There are 2 types of sinusoidal heart rate pattern. A synchronized type sinusoidal heart rate pattern may indicate more advanced fetal compromise than is associated with a reciprocal type pattern.

Animals↗

An approach to construct simplified measures of dietary patterns from exploratory factor analysis.

Exploratory factor analysis might work well in elucidating the major dietary patterns prevailing in specific study populations. However, patterns extracted in one study population and their associations with disease risk cannot be reproduced with this data-specific method in other study populations. To construct less population-dependent pattern variables of similar content as original exploratory patterns, we proposed to derive so-called simplified pattern variables. They represent the sum of the unweighted standardised food variables which loaded high at the pattern of interest. Data from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study suggest that these simplified pattern variables might adequately approximate factor analysis-based dietary patterns. A simplified pattern variable based on the six highest loading food variables showed a correlation >0.95 with the originally derived factor score, which consisted of forty-seven food variables. Moreover, simplified pattern variables might adequately approximate patterns across different study populations. A simplified pattern variable showed similar factor loadings, ranging from 0.34 to 0.52, as well as similar associations with nutrient intake as a 'western' pattern originally reported from an US study population. These simplified pattern variables can subsequently be used to study pattern associations with disease risk, especially in multi-centre studies. It is therefore an approach that might overcome one of the most frequently claimed limitations of factor analyses applied in epidemiology: their non-comparable risk estimates.

Diet↗

Long-term stability of food patterns identified by use of factor analysis among Swedish women.

Limited data exist on the reproducibility of food patterns measured by factor analysis as well as on the use of stability of patterns over time. Our primary objective was to explore the long-term stability of food patterns derived by confirmatory factor analysis among 33,840 women participating in the Swedish Mammography Cohort. Our secondary objective was to compare factor solutions from confirmatory factor analysis with those derived by use of exploratory factor analysis. Diet was assessed by a food frequency questionnaire in 1987 and 1997, and food patterns were derived by the use of exploratory and confirmatory factor analysis. We observed four major food patterns (Healthy, Western/Swedish, Alcohol, and Sweets) at both time points. Correlations between confirmed food patterns in 1987 and 1997 were 0.37 for the Healthy pattern, 0.27 for the Western/Swedish pattern, 0.54 for the Alcohol pattern, and 0.44 for the Sweets pattern (P < 0.0001 for all associations). Patterns derived by the use of exploratory factor analysis were strongly associated with those derived by the use of confirmatory factor analysis (r >/= 0.90, P < 0.0001, for all associations). The patterns derived in this study were similar to those derived in other studies, indicating reproducibility of food patterns across populations. Our study suggests that food patterns measured by the use of confirmatory factor analysis are reproducible over time, and weaker correlations observed may reflect natural changes in eating behavior, the food supply, and/or perceptions of what is considered healthy. Testing whether patterns measured over a long time period can be used in analytic studies is the next step in assessing the validity of this method.

Alcohol Drinking↗

Nailfold videocapillaroscopic patterns and serum autoantibodies in systemic sclerosis.

BACKGROUND: Microvascular lesions are a predominant feature in systemic sclerosis (SSc) and seem to play a central pathogenetic role. Recently, we graded scleroderma microangiopathy by nailfold videocapillaroscopy (NVC) into three NVC patterns (early, active and late). The aim of the present study was to confirm, in a larger number of SSc patients, the presence of three patterns of microvascular damage, and to detect any possible relationship between these patterns and both specific serum autoantibodies and the subsets of cutaneous involvement. METHODS: Two hundred and forty-one consecutive patients (227 women and 14 men) affected by SSc were recruited. One hundred and forty-eight patients were affected by limited cutaneous SSc (lSSc) and 93 patients by diffuse cutaneous SSc (dSSc). The ages at onset of Raynaud's phenomenon (RP) and SSc, the durations of RP and SSc, ANA and antitopoisomerase I (anti-Scl70) and anticentromere (ACA) antibodies were investigated in all patients. The SSc patients were subdivided on the basis of the NVC pattern into three groups. RESULTS: A statistically significant correlation was found between the NVC patterns and the durations of both RP and SSc (P<0.001). Enlarged and giant capillaries, together with haemorrhages, constituted the earliest NVC finding in SSc (early NVC pattern). These abnormalities were mostly expressed in the active NVC pattern. Loss of capillaries, ramified capillaries and vascular architectural disorganization were increased in the late NVC pattern. Age and the duration of both RP and SSc were lower in 24 patients complaining of RP alone. Anti-Scl70 antibodies were statistically less frequent in the early vs both the active and the late NVC pattern, whereas no significant correlation was found between the presence of anti-Scl70 antibodies and the duration of either RP or SSc. ACA positivity was more frequent in patients with longer RP duration. Patients with lSSc had shorter SSc duration and showed the early or active NVC pattern more frequently. Conversely, patients with dSSc showed longer disease duration and mostly showed the late NVC pattern. CONCLUSIONS: NVC is an appropriate tool for differential diagnosis between primary and secondary RP through the clear recognition of the early NVC scleroderma pattern. This study confirms, in a large number of SSc patients, the existence of three distinct NVC patterns that might reflect the evolution of SSc microangiopathy. The presence of anti-Scl70 antibodies seems be related to earlier expression of the active and late NVC patterns of SSc microvascular damage. The presence of ACA seems to be related to delayed expression of the late NVC pattern.

Adult↗

Predictors of Gleason pattern 4/5 prostate cancer on prostatectomy specimens: can high grade tumor be predicted preoperatively?

PURPOSE: Radical prostatectomy provides excellent cancer control in men with clinically localized prostate carcinoma. However, to our knowledge preoperative parameters for distinguishing indolent from clinically significant cancer are not well characterized. In fact, recent evidence suggests that the percent of Gleason pattern 4/5 carcinoma in the complete radical prostatectomy specimen is one of the strongest predictors of prostate cancer progression and a valid measure of cancer severity. However, it is unclear whether preoperative parameters, including biopsy Gleason pattern 4/5 carcinoma, may predict radical prostatectomy Gleason pattern 4/5 disease and, thereby, distinguish indolent from clinically significant cancer. MATERIALS AND METHODS: We prospectively obtained 101 consecutive radical prostatectomy specimens and processed them in whole mount fashion. In addition to total tumor volume, we determined tumor volume for each Gleason pattern. Biopsy tumor area was measured in a similar fashion. Univariate and multivariate analyses were performed to identify preoperative clinical and pathology parameters for predicting Gleason pattern 4/5 carcinoma on prostatectomy specimens. RESULTS: Biopsy Gleason score 7 or greater, Gleason pattern 4/5 carcinoma, perineural invasion and biopsy tumor area had statistically significant associations for identifying Gleason pattern 4/5 carcinoma on prostatectomy specimens. Logistic regression models for predicting any or greater than 10% Gleason pattern 4/5 carcinoma on prostatectomy specimens revealed that an area of pattern 4/5 disease of greater than 0.01 cm.2 on biopsy was the best single predictor with odds ratios of 15.0 (95% confidence interval 3.3 to 69.0, p = 0.0005) and 3.9 (95% confidence interval 1. 4 to 10.9, p = 0.009), respectively. For predicting any pattern 4/5 carcinoma on prostatectomy specimens a biopsy area of pattern 4/5 disease of greater than 0.01 cm.2 had only 38% sensitivity but 96% specificity. Similarly for predicting significant pattern 4/5 disease on prostatectomy specimens, defined as 10% or greater pattern 4/5, sensitivity and specificity for a biopsy area of greater than 0.01 cm.2 were 34% and 88%, respectively. Therefore, due to high false-negative rates these models had limited predictive value on an individual basis. CONCLUSIONS: Biopsy parameters such as Gleason pattern 4/5 carcinoma may provide adequate specificity for predicting clinically significant cancer, as defined by high grade Gleason patterns in the corresponding radical prostatectomy specimen. However, the accuracy of these parameters for predicting indolent cancer is limited by a prohibitive rate of false-negative findings.

Adenocarcinoma↗

Microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks.

A microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks due to on-ramps, merge bottlenecks (a reduction of highway lanes), and off-ramps is presented. The basic postulate of three-phase traffic theory is used, which claims that homogeneous (in space and time) model solutions (steady states) of synchronized flow cover a two dimensional region in the flow-density plane [B. S. Kerner, Phys. Rev. Lett. 81, 3797 (1998); Trans. Res. Rec. 1678, 160 (1999)]. Phase transitions leading to diverse congested patterns, pattern evolution, and pattern nonlinear features have been found. Diagrams of congested patterns, i.e., regions of the pattern emergence dependent on traffic demand, have been derived. Diverse effects of metastability with respect to the pattern formation have been found. The microscopic theory allows us to explain the main empirical pattern features at on-ramps and off-ramps which have recently been found [B. S. Kerner, Phys. Rev. E 65, 046138 (2002)]. (i) Rather than moving jams, synchronized flow first occurs at bottlenecks if the flow rate is slowly increasing. Wide moving jams can spontaneously occur only in synchronized flow. (ii) General patterns (GP) and synchronized flow patterns (SP) can spontaneously emerge at the bottlenecks. There can be the widening SP (WSP), the moving SP (MSP), and the localized SP. (iii) At on-ramps cases of "weak" and "strong" congestion should be distinguished. In contrast to weak congestion, under strong congestion the flow rate in synchronized flow in GP reaches a limit flow rate, the frequency of the moving jam emergence reaches a maximum, i.e., the GP characteristics under strong congestion do not depend on traffic demand. (iv) At the off-ramp GP with weak congestion occur. (v) A study of the pattern formation on a highway with two bottlenecks shows that diverse expanded patterns can occur, which cover both bottlenecks. SP first emerged at the downstream bottleneck can be caught at the upstream bottleneck (the catch effect). MSP, WSP, or wide moving jams first emerged at the downstream bottleneck induce diverse patterns at the upstream bottleneck. The onset of congestion at the upstream bottleneck can lead to an intensification of congestion at the downstream bottleneck. This causes a change in the pattern type and/or the pattern features.

Journal Article↗

Reassessment of the PAS patterns in uveal melanoma.

BACKGROUND: Previous work has highlighted the prognostic importance of patterns of periodic acid Schiff (PAS) staining (the Folberg patterns) in uveal melanoma. These patterns have been ascribed to blood vessels but the patterns are different from those seen with other staining techniques for blood vessels. It has recently been shown that microvessel density is the dominant prognostic factor in uveal melanoma. This study reinvestigates the nature and significance of the PAS patterns. METHODS: The PAS patterns were compared with the patterns seen with conventional connective tissue stains and with the patterns seen in sections stained for the presence of blood vessels (by immunohistochemistry for factor VIII related antigen). The PAS patterns were determined on a panel of 117 cases of uveal melanoma. The prognostic significance of each of these patterns was determined and, as more than one pattern can exist in a tumour, principal components analysis was performed to determine the number of underlying factors. RESULTS: Comparison of the PAS patterns with other stains demonstrates that they are based on connective tissue including fibrovascular tissue. Five of the nine PAS patterns carried prognostic significance on univariate analysis. Principal components analysis suggested that these patterns represented three underlying factors, which were tentatively identified as representing disordered growth (factor 1), emergence of rapidly growing subclones (factor 2), and section orientation (factor 3). CONCLUSIONS: The PAS patterns are based on fibrovascular tissue and can be ascribed to three underlying factors. The first two of these factors carried prognostic significance and the first (disordered growth) retained independent prognostic significance in a multivariate Cox model which included microvessel density and tumour size.

Biomarkers, Tumor↗

Effect of early exposure to patterned sound on unit activity in rat inferior colliculus.

1. Young rats were exposed to one of two patterns of sounds for 5 h daily during the first 4 mo of life. The up pattern consisted of a tone swept from 6 to 9 kHz in 1 s alternated with a 1-s noise burst. The down pattern differed in that the sweeps were from 9 to 6 kHz. 2. A pattern evoked more spikes, on the average, from units in the inferior colliculus of rats exposed to that pattern than from units in animals exposed to the other pattern. 3. The exposure effect was most pronounced in the unit responses to the noise-burst segment within a pattern suggesting a long-lasting, malleable influence of the tone sweep which defined the pattern. Responses to pattern noise components were less for both exposed groups than for the unexposed controls, suggesting that inhibitory mechanisms were responsible for the pattern discrimination evident in the responses of the exposed unit population. 4. Unit responses in unexposed rats were somewhat more selective for the down pattern so that the resulting shift in response selectivity was relatively more apparent for exposure to the up pattern. 5. While control and down-exposed units generally responded more to both the tone sweep and noise burst in one pattern, a large proportion of the up-exposed unit population continued to favor the down over the up-swept tone, but responded more to the up-pattern noise bursts. This suggests that the unit responses to the noise bursts did not simply reflect prolonged responses to the tone sweeps. 6. No similar effects were seen for units from mothers similarly exposed to the same patterns.

Acoustic Stimulation↗

Fictive motor patterns in chronic spinal cats.

1. Fictive motor patterns were recorded in hind leg nerves of 10 adult chronic spinal cats (spinalized at T13). Four of these animals had been trained to step with their hind legs on a treadmill (late-spinal animals), whereas the remainder received no training and were examined a short time after spinalization (early-spinal animals). 2. A fictive pattern resembling the locomotor pattern for stepping was evoked in all animals in response to stimulation of the skin of the perineal region. (2-[2,6-Dichloroaniline]-2-imidazoline) hydrochloride (Clonidine) at doses ranging from 100 to 500 micrograms/kg iv facilitated the production of this pattern, particularly in early-spinal animals. 3. The fictive locomotor pattern in late-spinal animals was more complex than that occurring in early-spinal animals. In the latter the pattern consisted of an alternation of activity in flexor and extensor nerves, and changing leg position did not qualitatively alter the pattern, whereas in late-spinal animals the relative durations of the bursts in different flexors were usually not the same, and the pattern of flexor activity was dependent on leg position. 4. Moving the legs from extension to flexion progressively decreased the duration of flexor bursts, increased the cycle period, and decreased the ease with which the pattern could be evoked in both early- and late-spinal animals. 5. 1-beta-3,4-Dihydroxyphenylalanine (DOPA)/Isonocotinic acid 2-[(2-benzylcarbamoyl)ethyl]hydrazide (Nialamide) treatment following Clonidine in early-spinal animals increased the complexity of flexor burst activity. This, and other observations, indicates that DOPA and Clonidine do not have strictly identical actions on the locomotor pattern generator. 6. Stimulation of the paws in late-spinal animals produced two patterns of activity distinctly different from the locomotor pattern. of activity distinctly different from the locomotor pattern. One was a short sequence of high-frequency rhythmic activity (at approximately 8 c/s) in response to gently stimulating one paw with a water jet, and the other was a slow rhythm in flexor nerves in response to squeezing the paw. 7. The main conclusion of this investigation is that three distinctly different fictive motor patterns can be generated in chronic spinal cats depending on the method and site of stimulation. These patterns correspond to three different behaviors (locomotion, paw shake, and rhythmic leg flexion) that can be elicited in behaving chronic spinal cats in response to the same stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

[Daily life patterns associated with 18-months changes of disability among frail elderly living at home].

The purpose of this study was to investigate daily life patterns associated with changes of disability over 18-months among frail elderly living at home. Subjects were 50 frail elderly living at home who were interviewed at baseline, in July-September 1995. By detailed time budgets among them, five life patterns were classified. Lying-rest life pattern, Sitting-rest life pattern, Hobby life pattern, Walking life pattern, and Houseworking life pattern. Activities of daily living (ADL) measured by Extended ADL Index consisted of 8 items of Barthel Index and 4 items of TMIG Index of Competence. Information for follow-up were obtained from home health nurses or mail-questionnaires February-March in 1997. The results were as follows: All samples were able to be followed. Seven people died within the 18 months follow-up. Overall change of score on ADL was not seen between baseline and follow-up study. ADL improvement was seen in 45.0% and 43.7% had declines. Daily life patterns were not correlated with changes in ADL score. However, analysis of decline in ability to perform each activities, relative associations (not statistically significant) were found for changes in function and daily life patterns. Lying-rest life pattern and Sitting-rest life pattern elderly were more likely to decline in ADL than Walking life pattern and HouseworKing life pattern elderly. Hobby life pattern elderly only declined in walking. These findings support previous studies showing that disability of home frail elderly could be improved. Daily life pattern among them would be a helpful predictor of changes in specific physical performance over years.

Activities of Daily Living↗

Discrimination of coloured patterns by honeybees through chromatic and achromatic cues.

We investigated pattern discrimination by worker honeybees, Apis mellifera, focusing on the roles of spectral cues and the angular size of patterns. Free-flying bees were trained to discriminate concentric patterns in a Y-maze. The rewarded pattern could be composed of either a cyan and a yellow colour, which presented both different chromatic and achromatic L-receptor contrast, or an orange and a blue colour, which presented different chromatic cues, but the same L-receptor contrast. The non-rewarded alternative was either a single-coloured disc with the colour of the central disc or the surrounding ring of the pattern, a checkerboard pattern with non-resolvable squares, the reversed pattern, or the elements of the training pattern (disc or ring alone). Bees resolved and learned both colour elements in the rewarded patterns and their spatial properties. When the patterns subtended large visual angles, this discrimination used chromatic cues only. Patterns with yellow or orange central discs were generalised toward the yellow and orange colours, respectively. When the patterns subtended a visual angle close to the detection limit and L-receptor contrast was mediating discrimination, pattern perception was reduced: bees perceived only the pattern element with higher contrast.

Animals↗

Primate striate and prestriate cortical neurons during discrimination. II. separable temporal codes for color and pattern.

1. In the previous paper we reported our analysis of the responses of neurons in cortical areas V1, V2, and V4 to a set of stimuli that consisted of all 36 combinations of six colors and six patterns. Neurons in all three cortical areas simultaneously encoded information about both the color and pattern of the stimulus in the number and temporal distribution of spikes in their responses. To account for this ability, we propose that a neuron's response consists of separable temporal codes representing the color and pattern of the stimulus that are multiplexed together. 2. We used nonlinear regression to fit the model parameters to the data. We used the responses to 30 of the 36 stimuli as a training set to estimate the parameters of the model and the responses to the remaining 6 stimuli as a test set. After training, the model fitted the responses to stimuli in the training sets very well and predicted the responses to stimuli in the test sets. Thus neuronal responses to colored patterns contain separate temporal codes representing color and pattern. 3. After establishing the model parameters, we obtained the waveforms that represented each neuron's temporal codes for the six colors and six patterns of our stimulus set. We then proceeded with a series of analyses to determine whether these waveforms were viable candidates for neuronal codes. Cluster analysis revealed that there were only a few different classes of waveforms representing each color and pattern, and there were many neurons in each class. Further, neurons that used similar waveforms to represent one color or pattern also tended to use similar waveforms to represent other colors or patterns. The waveforms representing five of the six colors and three of the six patterns were similar in the two monkeys used in this study. 4. We compared the shapes of the code waveforms across cortical areas and found no differences among areas in the shapes of the waveforms representing four of the six colors. In contrast, we found that there were differences among areas in the shapes of the waveforms representing all six patterns. These results suggest that messages about color are encoded at an early level and are then propagated upward, but that messages about pattern are altered in each successive cortical area. 5. Our results offer a neurophysiological explanation for the psychophysical evidence that color and form are processed by different channels. We propose that the psychophysical channels for color and pattern arise from the separability of the temporal codes for color and pattern in the responses of single neurons. This hypothesis implies that psychophysical channels correspond to classes of temporal codes rather than to classes of neurons.

Animals↗

Pattern of FHIT gene expression in normal and leukaemic cells.

Chromosomal aberrations and inactivation of tumour suppressor genes are frequent in acute leukaemia. To determine whether the FHIT gene is involved in the development of leukaemia, we examined the FHIT transcript in 65 leukaemia cell lines, 5 fresh acute leukaemia patients at diagnosis and in complete remission, normal peripheral blood lymphocytes obtained from 14 healthy volunteers and Epstein-Barr (EB) virus transformed 5 B-cell lines (EB-lines), using nested reverse transcription-polymerase chain reaction and direct sequencing. The transcripts were classified into 4 patterns: pattern I revealed the normal transcripts only, pattern II the altered transcripts in addition to the normal transcripts, pattern III the altered transcripts without the normal transcripts and pattern IV an absence of normal and altered FHIT transcripts. Nineteen cell lines were classified as pattern I, 32 as pattern II, 2 as pattern III and 12 as pattern IV. The frequency of loss of FHIT expression (pattern III or IV) varied in each type of leukaemia cell line; the order ranked from the highest incidence was acute myeloid leukaemia (AML), T-cell acute lymphoblastic leukaemia (T-ALL), B-precursor ALL, B-ALL, and chronic myeloid leukaemia (CML). No genomic rearrangement was found in any samples examined. All of 5 patients showed same pattern II FHIT transcripts at 2 different stages of the disease. All normal peripheral blood lymphocytes and EB-lines were classified as pattern I or II. Our results suggested that patterns III and IV of FHIT transcripts might be associated with the development of a subset of leukaemia, while pattern II which has so far been reported as an aberrant transcript in varieties of malignant tumours might not be associated with leukaemogenesis.

Acid Anhydride Hydrolases↗

Neural control of a cyclic postural behavior in the crayfish, Procambarus clarkii: the pattern-initiating interneurons.

As part of its repertoire of defensive behaviors, the crayfish, Procambarus clarkii, may respond to mildly threatening tactile or visual stimuli from the front of its body by walking backwards. During this behavior, the abdomen undergoes complex cyclical movements involving flexion and extension of the postural musculature which cause the tail to alternately contact and withdraw from the substrate. Intracellular neuropil recordings and dye injections were used to search for the interneurons responsible for initiating this postural motor pattern in the crayfish abdomen. Several diverse morphological types of interganglionic pattern-initiating (PI) interneurons were found. Each interneuron, when driven intracellularly, was capable of eliciting the same motor program, in its entirety, throughout the abdominal nerve cord. During pattern generation, PI interneurons exhibited a burst of spikes preceding the motor output. Silencing single PI interneurons with hyperpolarizing current during pattern generation failed to affect the motor program, indicating a redundancy of pattern-initiating function. The observations of extensive dye-coupling with other parallel axons, consistent dye-coupling with other identified cells in the pattern-initiating system, and the presence of multiple spike amplitudes in the bursts suggested electrotonic coupling among the PI interneurons. An additional group of interganglionic interneurons, the partial pattern-initiating (PPI) interneurons, were found to comprise a significant subset of the pattern-initiating system. As with the PI cells, the PPI interneurons exhibited a complex burst of spikes just preceding the patterned motor program. However, the PPI interneurons were only capable of eliciting an incomplete, though recognizable, postural motor pattern. Silencing any PPI interneuron during pattern generation caused a deficit in the motor pattern, indicating either an absence or lesser degree of functional redundancy within the PPI interneuron population compared to that occurring within the PI interneuron group. We conclude that a large number of PI interneurons are presynaptic to a relatively small group of PPI interneurons which, in turn, conduct pattern-initiating signals to the ganglionic oscillators. Our results indicate that pattern-initiation is accomplished through a command system involving multiple command elements organized in a coordinated interganglionic network.

Animals↗