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Multiple clustered dermatofibroma (MCD) is a rare tumour which usually appears during the first and second decades of life. We report a man in whom the MCD was congenital, although during the first few years of his second decade it extended to involve a broad zone on the left hip, gluteal region and upper thigh.
PURPOSE: To characterize the epileptogenic zone in neocortical epilepsy (NE) by using magnetoencephalography (MEG). METHODS: We defined and compared locations of single and multiple clusters of equivalent current dipoles (ECDs) for interictal spikes with MRI findings, ictal-onset zones (IOZs) from subdural electroencephalography (SDEEG), resected areas, and postsurgical outcomes of 20 patients who underwent cortical resection for medically intractable NE. RESULTS: Fourteen patients had single clusters; six had multiple clusters. Overlap of clusters and IOZs defined group A (nine patients), in which a single cluster coincided with the IOZ; group B1 (four patients), in which a single cluster was within or partially overlapped the IOZ; group B2 (five patients), in which multiple-cluster sections overlapped IOZs; group C (two patients; one single; one multiple), in which no overlap was seen. More single clusters (nine of 14) than multiple clusters (none of six) coincided with the IOZ (p = 0.014). More patients with single clusters (10 of 14) than patients with multiple clusters (one of six) had seizure-free outcomes (p = 0.049). Eight of nine patients in group A, versus three of 11 in groups B1, B2, and C, achieved seizure-free outcomes (p = 0.0098). Correlations between MRI findings and postsurgical outcomes were not statistically significant; eight of 13 patients with single lesions, one of four with no lesions, and two of three with multifocal lesions had seizure-free outcomes. CONCLUSIONS: In neocortical epilepsy, MEG ECD clusters correlated with SDEEG IOZs. Single clusters indicated discrete epileptogenic zones that required complete resection for seizure-free outcome. Multiple clusters necessitated that the multiple or extensive epileptogenic zones be completely identified and delineated by SDEEG.
Multiple clustered dermatofibromas constitute an uncommon entity, of which we have collected seven cases in the literature. We observed the case of a 4-year-old girl, who had dermatofibromas confluent in a central plaque of fibrous aspect, located in the lumbar region. The immunohistochemical study showed positive staining for Factor XIIIa antibody, confirming its origin in the dermal dendrocyte.
A 37 year-old man developed, over 20 years, multiple clustered dermatofibromas on the left thigh. Three similar cases have been described previously and the benign course of this lesion has been referred to. Analysis of collagen amino acids revealed a sharp increase of hydroxylysine on the fibrous central zone, suggesting an abnormal accumulation of type IV collagen.
We explore the idea of evidence accumulation (EAC) for combining the results of multiple clusterings. First, a clustering ensemble--a set of object partitions, is produced. Given a data set (n objects or patterns in d dimensions), different ways of producing data partitions are: 1) applying different clustering algorithms and 2) applying the same clustering algorithm with different values of parameters or initializations. Further, combinations of different data representations (feature spaces) and clustering algorithms can also provide a multitude of significantly different data partitionings. We propose a simple framework for extracting a consistent clustering, given the various partitions in a clustering ensemble. According to the EAC concept, each partition is viewed as an independent evidence of data organization, individual data partitions being combined, based on a voting mechanism, to generate a new n x n, similarity matrix between the n patterns. The final data partition of the n patterns is obtained by applying a hierarchical agglomerative clustering algorithm on this matrix. We have developed a theoretical framework for the analysis of the proposed clustering combination strategy and its evaluation, based on the concept of mutual information between data partitions. Stability of the results is evaluated using bootstrapping techniques. A detailed discussion of an evidence accumulation-based clustering algorithm, using a split and merge strategy based on the K-means clustering algorithm, is presented. Experimental results of the proposed method on several synthetic and real data sets are compared with other combination strategies, and with individual clustering results produced by well-known clustering algorithms.
BACKGROUND: Although patients with one to two dermatofibromas are common, cases of "multiple" dermatofibromas (more than 15 lesions) are rare and may occur in the context of altered or normal immune function. Patients with multiple dermatofibromas clustered in one anatomic area, by contrast, are strikingly rare. OBJECTIVE: The aim of our study was to present an additional case of multiple, clustered dermatofibroma (MCDF) and to summarize the literature concerning this entity. METHODS: We performed a MEDLINE (1960-2001) database search using keywords "dermatofibroma" AND "clustered" OR "agminated" OR "grouped." RESULTS: Five case reports were identified using this search strategy. These cases demonstrated substantial similarity in clinical features and behavior, specifically, the presence of pruritic symptoms, no clear inciting incident, an early active growth phase followed by stabilization, predilection for the lower extremity, and no report of sarcomatous transformation. CONCLUSION: Despite an active early growth phase, MCDF appears to follow a benign clinical course, with no report of sarcomatous transformation at up to 20 years followup.
BACKGROUND: Basal cell carcinoma (BCC) patients demonstrate considerable phenotypic diversity. The basis of this heterogeneity is poorly understood. We have shown that presentational phenotypes are associated with BCC numbers. Thus, patients with a cluster of new BCC at any presentation comprise a subgroup, termed MPP, that is at increased risk of developing numerous lesions. Patients with more than one cluster (multiple cluster MPP) are at particular risk. PROCEDURE: We determined in a cohort of BCC cases, whether: (i) tumor accrual was altered after clustering; and (ii) multiple cluster MPP is associated with characteristics linked with sensitivity to UV or, GSTT1, GSTM1, GSTM3, GSTP1, MC1R, CYP2D6, TNF-alpha, and VDR genotypes previously associated with BCC presentational phenotypes. RESULTS: (i) After clustering BCC accrual increased; and (ii) exposure to UV in single and multiple cluster MPP cases were similar. In multiple cluster cases, mean age at first presentation with a single tumor occurred earlier and, the frequencies of CYP2D6 EM (94.4%) and GSTT1 null (41.2%) were significantly greater (P = 0.028 and P = 0.004) than in single cluster cases (67.1 and 14.3%). The odds ratios for these associations with the multiple cluster MPP were large; 15.5 and 7.39, respectively. CONCLUSIONS: The finding of clusters of new, primary BCC is a critical event that is followed by markedly increased accrual of further tumors. Clustering occurs at a relatively late age and may be associated with a failure in immune surveillance. We propose the MPP is not the consequence of excessive UV exposure but reflects the presence of a distinct BCC subgroup defined by a combination of risk genes.
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Metallostars are complexes in which a single branching site bears a number of metallated arms. Although they are related to metallodendrimers, they have the advantage of being capable of extending in an unlimited sense; in contrast to metallodendrimers, steric interactions decrease with increasing generation number. In this paper a series of polyalkyne stars with four and six arms, based upon a single tetrahedral carbon core and a benzene core, respectively, are reported and their reactions with [Co2(CO)8] to give metallostars that contain multiple [C2Co2(CO)6] motifs are described.
The visual system commonly has to estimate the relative location of a textured region but the stimulus features used to perform that task are yet to be determined. The use of centroid, midpoint and peak activity cues would all be reasonable. In the current experiment an attempt was made to assess the relative efficacy of these three cues. The observers were required to indicate whether a cloud of either 3, 10 or 100 elements was located to the left or right of an imaginary line formed between two reference elements. Performance was compared to that expected from the use of the three cues. It was concluded that the cue used varied as the characteristics of the cloud changed and therefore that the visual system is not restricted to the use of a single cue type when localizing object clusters.
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The nucleotide and inferred amino acid sequence of three globin VIIB genes from the midge, Chironomus thummi thummi have been determined. These three genes are intronless, like all previously reported Chironomid globin genes. Transcription of globin genes VIIB-4, VIIB-5 (and/or VIIB-6) and VIIB-7 was demonstrated by S1 nuclease protection analysis. Comparison of actual and inferred globin VIIB amino acid sequences reveals that (i) most of the amino acid substitutions are conservative in nature, and (ii) none of the substitutions are expected to interfere with the ability of the globins to bind haem. Nucleotide sequence comparisons suggest that gene duplications and partial gene corrections (conversions) have occurred recently in the globin VIIB subfamily locus.
Cytosolic acetyl-CoA synthetase (AceCS1) activates acetate to supply the cells with acetyl-CoA for lipid synthesis. The cDNA for the mammalian AceCS1 has been isolated recently, and the mRNA was shown to be negatively regulated by sterols in cultured cells. In the current study, we describe the molecular mechanisms directing the sterol-regulated expression of murine AceCS1 by cloning and functional studies of the 5'-flanking region of the AceCS1 gene. An AceCS1 promoter-reporter gene (approximately 2.1 kilobase pairs) was negatively regulated when sterols were added to the medium of cultured cells, and the promoter was markedly induced by co-transfection of a plasmid that expresses the transcriptionally active nuclear form of either sterol regulatory element-binding protein (SREBP)-1a or -2 in HepG2 cells. Sequence analysis suggested that the AceCS1 promoter contains an E-box, two putative CCAAT-boxes, eight sterol regulatory element (SRE) motifs, and six GC-boxes. Gel shift assays demonstrated that all eight SRE motifs bound purified SREBP-1a in vitro with similar affinity. Luciferase reporter gene assays revealed that sterol regulation was critically dependent on three closely spaced SRE motifs and an adjacent GC-box. However, mutation of two putative upstream CCAAT-boxes did not affect SREBP dependent activation. Electrophoretic mobility "supershift" analyses confirmed that both Sp1 and Sp3 bound to the critical GC-box. In addition, transfection studies in Drosophila SL2 cells demonstrated that SREBP synergistically activated the AceCS1 promoter along with Sp1 or Sp3 but not with nuclear factor-Y.
Drosophila melanogaster 125I-5S RNA was annealed to salivary gland preparations of 6 species in the virilis group of Drosophila. Two patterns of annealing were found. D. virilis, D. montana and D. borealis showed three 5S gene clusters on chromosome 5; Sd-f and Wc-j were strongly labeled, but Xa-e was weakly labeled. D. montana and D. borealis have a greater percentage of their total 5S cistroms at S d-f than does D. virilis. D. americana americana, D. americana texana and D. novamexicana showed 2 sites labeled; no label was seen at Sd-f while Wc-j was weakly labeled and Xa-e was strongly labeled, the reciprocal of the previous pattern in the W-X region. Hybrids between D. a americana and D. virilis showed no difference in chromosome banding at the sites of the 5S clusters despite their pattern difference. D. a texana X D. virilis, on the other hand, did show a difference in staining the Xa-e region. These patterns fall squarely into the biosystematic groupings deduced by many previous workers.
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This study was aimed at dissecting the cellular mechanisms that underly the growth of actively expanding human goiter nodules. Thirty-two nodules from different patients, all removed because of steady recent growth, were serially sectioned and screened for 1) histomorphological signs of cell proliferation and 2) in situ expression of the immunohistochemically stained p21ras protooncogene product. Bovine, porcine, and rat thyroid glands (the latter from both T4- and perchlorate-treated animals) were used as controls. In normal glands, only a few follicular cells contain substantial amounts of stainable p21ras. Some of these cells are unusually large, but do not proliferate. In contrast, all goiter nodules contain areas where the epithelial cells are morphologically grossly altered and heavily loaded with p21ras. Cells of this type are mostly clustered in large cohorts coating whole follicles or entire groups of follicles. Only a small fraction of these activated cells actually proliferates at any one point in time. Actively replicating cells are scattered in tiny foci all over the nodules. The earliest proliferating buds are solid, but soon begin to generate microfollicles that enlarge by adding new cells to the follicular epithelium. Regionally heterogeneous p21ras content in morphologically identical cells suggests that growth occurs in bursts and waves. We conclude that goiter nodules grow by episodic proliferation of heterogeneous cohorts of epithelial cells from which new follicles are generated. Only a tiny fraction of all goiter cells proliferate at any one point in time. The molecular mechanisms governing these growth processes are unknown.
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Rapid and accurate discrimination of single units from extracellular recordings is a fundamental process for the analysis and interpretation of electrophysiological recordings. We present an algorithm that performs detection, characterization, discrimination, and analysis of action potentials from extracellular recording sessions. The program was entirely written in LabVIEW (National Instruments), and requires no external hardware devices or a priori information about action potential shapes. Waveform events are detected by scanning the digital record for voltages that exceed a user-adjustable trigger. Detected events are characterized to determine nine different time and voltage levels for each event. Various algebraic combinations of these waveform features are used as axis choices for 2-D Cartesian plots of events. The user selects axis choices that generate distinct clusters. Multiple clusters may be defined as action potentials by manually generating boundaries of arbitrary shape. Events defined as action potentials are validated by visual inspection of overlain waveforms. Stimulus-response relationships may be identified by selecting any recorded channel for comparison to continuous and average cycle histograms of binned unit data. The algorithm includes novel aspects of feature analysis and acquisition, including higher acquisition rates for electrophysiological data compared to other channels. The program confirms that electrophysiological data may be discriminated with high-speed and efficiency using algebraic combinations of waveform features derived from high-speed digital records.