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At least 19 recordsLinked to original sources
PubMed1991

Ridge detection tactility deficits associated with carpal tunnel syndrome.

A ridge detection threshold task was administered to patients diagnosed as having carpal tunnel syndrome for studying performance in an occupationally relevant functional tactile inspection task. Thresholds were compared with a reference group of subjects not having carpal tunnel syndrome symptoms, performing the same task. The threshold detection task used the method of limits for studying the effects of carpal tunnel syndrome, rate of ridge height changes, ridge gradient, and direction of shearing against the skin on ridge detection thresholds for a repeated measures factorial experimental design. Sixteen carpal tunnel syndrome hands and 30 normal hands were studied. Average ridge detection threshold was 0.08 mm for the normal subjects and increased to 0.20 mm for the carpal tunnel syndrome subjects. No significant age effect was observed. These results suggest that workers having carpal tunnel syndrome may not detect an edge or surface defect in a tactile inspection task unless it was more than twice as high as detected by workers without CTS.

Adult↗
PubMed2004

Moiré interferogram phase extraction: a ridge detection algorithm for continuous wavelet transforms.

We present a procedure using continuous wavelet transforms (CWTs) to extract the phase information from moiré interferograms. The relationship between precise ridge detection of the two-dimensional CWT magnitude map and accurate phase extraction is detailed. A cost function is introduced for the adaptive selection of the ridge, and a computationally inexpensive implementation of the cost function ridge detection algorithm is explored with dynamic programming optimization. The results of the proposed ridge detection algorithm on actual interferograms are illustrated. Moreover, the resulting extracted phase is demonstrated to be smooth and accurate. As a result, the sensitivity of the moiré interferometry method is improved to obtain a pixel-by-pixel in-plane strain distribution map.

Journal Article↗
PubMed1986

Computing the skeleton of coronary arteries in cineangiograms.

In this paper we describe techniques to determine the skeleton of coronary arteries and to measure their medically significant geometric properties (such as boundaries and orientations) in cineangiograms. We use these geometric properties for segmentation, i.e., for separating the image of the arteries from the background. The purpose of this segmentation is to produce a structural description of the arterial tree for high-level processing. Our technique is completely automatic, efficient, and reliable. Our technique starts with the detection of skeleton points from a local ridge detector using density profiles of the arteries. Local orientations of skeleton points are obtained directly from the ridge detection or from local edge directions. Boundaries of the arteries are computed from the density profile along a straight line perpendicular to the skeleton. From this, a sequential and raster-scan tracking procedure is applied to obtain segments of the arteries from two scanning directions. The final segments are generated by merging all the segments.

Algorithms↗
PubMed2025

MIA-Jet: Multi-scale Identification Algorithm of Chromatin Jets.

The mammalian genome is organized into large-scale chromosome territories, compartments, domains, and at the smallest scale, chromatin loops and stripes. The newest element is a chromatin jet, a diffused line perpendicular to the main diagonal in the Hi-C contact map, which was reported in quiescent mammalian lymphocytes supporting a two-sided symmetric cohesin loop extrusion model. A similar structure is observed in Repli-HiC data, where relatively thin and straight chromatin fountains indicate coupling of DNA replication forks. However, the precise biological implications of these jet-like structures are unknown due to the limitations in computational methods. We developed MIA-Jet, a multi-scale ridge detection algorithm that can accurately detect jets of variable lengths, widths, and angles. When tested on Hi-C, Repli-HiC, ChIA-PET, ChIA-Drop, and Micro-C data in mouse, human, roundworm, and zebrafish cells, MIA-Jet outperformed existing methods. In human cells, jets were enriched in cohesin loading sites and early replication initiation zones. Applying MIA-Jet to Hi-C data generated from protein-degraded cells revealed that jets are dependent on cohesin but not YY1, and jet signals are strengthened after depleting WAPL. We envision MIA-Jet to be broadly applicable to any 3D genome mapping data, thereby providing new insights into the functional roles of chromatin jets.

3D genome mapping↗
PubMed2004

Design of steerable filters for feature detection using canny-like criteria.

We propose a general approach for the design of 2D feature detectors from a class of steerable functions based on the optimization of a Canny-like criterion. In contrast with previous computational designs, our approach is truly 2D and provides filters that have closed-form expressions. It also yields operators that have a better orientation selectivity than the classical gradient or Hessian-based detectors. We illustrate the method with the design of operators for edge and ridge detection. We present some experimental results that demonstrate the performance improvement of these new feature detectors. We propose computationally efficient local optimization algorithms for the estimation of feature orientation. We also introduce the notion of shape-adaptable feature detection and use it for the detection of image corners.

Algorithms↗
PubMed2006

Blind multiridge detection for automatic nondestructive testing using ultrasonic signals.

Ultrasonic imaging has been a significant means for nondestructive testing (NDT). Recently the NDT techniques via the ultrasonic instrumentation have shown the striking capability of the quality control for the material fabrication industry. To the best of our knowledge, all existing signal processing methods require either the a priori information of the ultrasonic signature signals or the manual segmentation operation to achieve the reliable parameters that characterize the corresponding mechanical properties. In this paper, we first provide a general mathematical model for the ultrasonic signals collected by the pulse-echo sensors, then design a totally blind novel signal processing NDT technique relying on neither a priori signal information nor any manual effort. Based on the automatic selection of optimal frame sizes using a proposed new criterion in our scheme, the signature signal can be blindly extracted for further robust multiridge detection. The detected ridge information can be used to estimate the transmission and attenuation coefficients associated with any arbitrary material sample for the fabrication quality control.

Journal Article↗
PubMed1998

In vivo high resolution 3D-QCT of the human forearm.

In vivo examinations of bone microarchitecture have become available recently through high resolution computed tomography (3D-QCT) and magnetic resonance imaging. The spatial resolution of the resulting images, however, is not sufficient to depict individual trabeculae in their true shape. Nevertheless, structural indices such as relative bone volume, trabecular number, mean thickness and mean separation can be extracted with the help of a ridge detection algorithm. Precision of the procedure is of the order of 1%, accuracy is ascertained using a micro-CT based calibration. In this work we report first results of time serial examinations. Eighteen healthy postmenopausal women (no HRT) were measured at months 0, 6, and 12, and the temporal changes were analyzed. Examination site was the distal radius. The above mentioned structural indices, the average densities and the thickness of the cortical shell were determined. Of the 18 women 6 showed no significant bone loss of any kind, 5 lost primarily cancellous bone, 4 lost primarily cortical bone, and 3 had a substantial loss of cortical as well as cancellous bone. We conclude that even in a homogenous group such as postmenopausal women, there are considerable differences in the reason why bone is weakened and that high resolution 3D-QCT allows to differentiate between various types of bone loss.

Bone Density↗
PubMed1997

Direct visualization of collagen-bound proteoglycans by tapping-mode atomic force microscopy.

Most studies on the interaction of collagen with proteoglycans, two universal components of connective tissues, use technical approaches which substantially modify the shape and size of the proteoglycans themselves. In the present study unfixed, untreated collagen fibrils from rat tail tendon were dehydrated and observed by tapping-mode atomic force microscopy. The surface of collagen fibrils immediately reveals a periodic alternation of gap and overlap zones. A thin, transverse ridge decorates the gap zone, while other filamentous structures run on the fibril surface, either parallel or perpendicular to the fibril axis. These surface structures are much enhanced by Cupromeronic Blue preincubation, while pretreatment with chondroitinase ABC removes them completely, leaving barely detectable transverse ridges. The ridge and filaments are likely to represent, respectively, the core protein and the glycosaminoglycan side chains of proteoglycans, displayed with a far better resolution than with conventional histochemical or immunohistochemical techniques. Our data suggest that proteoglycan molecules are capable of different, multiple interactions with the collagen fibril surface as well as with each other.

Animals↗
PubMed1979

Recovery of sensibility after suture of digital nerves.

A group of 49 patients with 74 injured digital nerves was studied more than 5 years following epineurial nerve suture. Three tests of return of sensibility were used: von Frey plastic filaments, a modified Weber two-point discrimination device, and a dynamic test--the plastic ridge. The correlation between two-point discrimination and tactilegnosis in the range of 8 to 12 mm was poor. The plastic ridge device detects the presence or absence of tactilegnosis in patients in the intermediate range of two-point discrimination between 8 and 12 mm. Of the factors studied, the patient's age at the time of nerve suture was found to be directly related to the return of sensibility by both two-point discrimination and ridge criteria.

Adolescent↗
PubMed1991

Early changes in the forestomach of rats, mice and hamsters exposed to dietary propionic and butyric acid.

Groups of five male and five female rats, mice and hamsters were fed diet containing 4% propionic or butyric acid for 7 days. Evidence of damage and cellular proliferation in the epithelium of the forestomach and limiting ridge was detected in all three species. Changes were particularly marked in animals fed butyric acid diet and rats appeared to be the most sensitive species. It is postulated that tumours of the forestomach reported in rats after long-term feeding of propionic acid diet may be a consequence of continued damage and repair, and that butyric acid, which occurs naturally in foods at concentrations up to 5%, would be at least as potent as propionic acid if similarly tested.

Administration, Oral↗
PubMed1997

Posterior deviation of left ventricular outflow tract septal components without ventricular septal defect.

OBJECTIVE: To describe 11 patients with narrowing of the left ventricular outflow tract caused by angular posterior deviation of both the outlet septum and the upper part of trabecular septum, which was diagnosed by cross sectional echocardiography in all and confirmed by angiocardiography in seven. RESULTS: Four patients had a subaortic systolic pressure gradient ranging from 23 to 70 mm Hg by Doppler echocardiography; cardiac catheterisation showed a significant (60 and 104 mm Hg) systolic pressure gradient in two. In four cases aortic regurgitation and two tricuspid pouches were shown by Doppler echocardiography, angiocardiography, or both. Four cases had a ridge at the angulation point on echocardiographic examination. Three patients were operated on for systolic pressure gradients of the left ventricular outflow tract and one for severe aortic regurgitation. There was proliferation of collagen-rich fibrous tissue in the subendocardial region on histopathological examination of the myectomy material. A ventricular septal defect had been diagnosed previously by contrast echocardiography in one patient; thus ventricular septal defects may close spontaneously over a period of time including fetal life. A subaortic ridge was detected in one patient at follow up. CONCLUSIONS: Deviation of the outlet and trabecular septa should be considered as a cause of ventricular outflow tract obstruction even when no ventricular septal defect is present.

Adolescent↗
PubMed1999

Nomogram of the fetal alveolar ridge: a possible screening tool for the detection of primary cleft palate.

OBJECTIVE: The objective of this study was to obtain a nomogram of the fetal alveolar ridge development, as a basis for the diagnosis of primary cleft palate. DESIGN: A cross-sectional study of 323 normal pregnant women of 14-32 weeks' gestation. Several biometric measurements were obtained throughout pregnancy, including the width of the fetal alveolar ridge. RESULTS: A nomogram of the width of the fetal alveolar ridge during 14-32 weeks' gestation is presented. A linear growth function was observed between alveolar ridge width and gestational age, biparietal diameter, head circumference, femoral length and humeral length. The alveolar ridge width in all eight cases of cleft palate was above two standard deviations and the 90th centile of our nomogram. CONCLUSION: We provide a nomogram of the growth of the fetal alveolar ridge between 14 and 32 weeks' gestation. This will aid the detection of primary cleft palate during routine prenatal sonography.

Alveolar Process↗
PubMed1997

Parallel expression of Sox9 and Col2a1 in cells undergoing chondrogenesis.

To assess the role of the transcription factor Sox9 in cartilage formation we have compared the expression pattern of Sox9 and Col2a1 at various stages of mouse embryonic development. Expression of Col2a1 colocalized with expression of Sox9 in all chondroprogenitor cells. In the sclerotomal compartment of somites the onset of Sox9 expression preceded that of Col2a1. A perfect correlation was also seen between high levels of Sox9 expression and high levels of Col2a1 expression in chondrocytic cells. However, no Sox9 expression was detected in hypertrophic chondrocytes; only low levels of Col2a1 RNA were found in the upper hypertrophic zone. Coexpression of Sox9 and Col2a1 was also seen in the notochord. At E11.5 Sox9 expression in the brain and spinal neural tube was more widespread than that of Col2a1 although at E14.5 Sox9 and Col2a1 transcripts were colocalized in discrete areas of the brain. Distinct differences between Sox9 and Col2a1 expression were observed in the otic vesicle at E11.5. At E8.5, expression of Sox9 but not of Col2a1 was seen in the dorsal tips of the neural folds and after neural tube closure also in presumptive crest cells emigrating from the dorsal pole of the neural tube. No Col2a1 expression was detected in gonadal ridges in which high levels of Sox9 expression were detected. Together with our previous results showing that the chondrocyte-specific enhancer element of the Col2a1 gene is a direct target for Sox9, these results suggest that Sox9 plays a major role in expression of Col2a1. The correlation between high expression levels of Sox9 and high expression levels of Col2a1 in chondrocytes suggests the hypothesis that high levels of Sox9 are needed for full expression of the chondrocyte phenotype; lower levels of Sox9 such as in neuronal tissues which are also associated with lower expression levels of Col2a1 would be compatible with other cell specifications.

Animals↗
PubMed1993

Ultraviolet luminescence from latent fingerprints.

Illumination of latent fingerprints on white paper using 266-nm radiation from a Nd:YAG laser and photographic detection of their ultraviolet fluorescence, produces images with good ridge detail. The detection rate was 69% in a survey of fingerprints from 34 people compared with only 23% using an argon-ion laser at 514 nm. Prolonged exposure to UV light decreased the inherent UV fluorescence intensity but no adverse effects were observed on subsequent treatment with 1,8-diazafluoren-9-one or ninhydrin.

Aging↗
PubMed1996

A receptor tyrosine kinase, Sky, and its ligand Gas 6 are expressed in gonads and support primordial germ cell growth or survival in culture.

Although a number of growth factors and their receptors are involved in the proliferation and differentiation of primordial germ cells (PGCs), the only factor that has been shown to be active in vivo is Steel factor, a ligand for c-Kit. To identify new growth factor receptors that may be required for PGCs function in vivo, we used an reverse transcription-polymerase chain reaction-based strategy to screen for protein kinase genes expressed in PGC-derived embryonic germ cells. We report here that one such gene encoding the receptor tyrosine kinase, Sky, is expressed in both PGCs and their supporting cells in male genital ridges after 11.5 dpc. Interestingly, Sky expression was not detected in female genital ridges, although transcripts were detected in supporting cells in the developing ovary at later stages. Gas 6, a ligand for Sky, was also expressed in interstitial cells which surround Sky positive cells in genital ridges, and, in addition, it supported PGC growth or survival in culture. After birth, Sky expression in testis was restricted to Sertoli cells, and Gas 6 was detected around peritubular cells and Leydig cells. These results suggest that Gas 6-Sky signaling plays a role in PGC growth, sexual differentiation, and Sertoli cell functions in vivo. Sky expression in Sertoli cells diminished by 3 weeks of age, when haploid germ cells first appear. On the other hand, the expression in Sertoli cells was markedly upregulated in the testis of germ cell-deficient W/Wv and jsd/jsd mice. The results suggest that signals from differentiated germ cells suppress Sky gene expression in Sertoli cells. High-resolution chromosomal mapping of Sky is also reported.

Animals↗
PubMed1984

Avian feather development: relationships between morphogenesis and keratinization.

Morphogenesis and expression of the alpha and beta keratin polypeptides are controlled by epidermal-dermal interactions during development of avian skin derivatives. We have examined the relationship between morphogenesis of the embryonic feather and expression of the feather alpha and beta keratins by routine histology, indirect-immunofluorescence, and SDS-PAGE. Initially beta keratins are expressed only in the feather sheath. Following barb ridge morphogenesis beta keratins can be detected in the barb ridge, coincident with the differentiation of barb ridge cells into eight distinct morphological types. Beta keratinization occurs in gradients; from feather apex to base, and from periphery of the barb ridge to the interior. The onset of beta keratinization in the barb ridges is paralleled by an increase in the major feather beta keratin polypeptides, as detected by SDS-PAGE. The alpha keratins are present in both the periderm and feather sheath at early stages of feather development, but become greatly reduced after hatching, when the down feather emerges from the sheath.

Animals↗
PubMed2002

Conservation of the function of DMRT1 regulatory sequences in mammalian sex differentiation.

Among genes involved in sex determination and differentiation, DMRT1 is the only one characterized to date containing a domain (the DM domain) that is conserved between phyla. To study DMRT1 transcriptional regulation within mammalian phyla, we generated transgenic mice that express green fluorescent protein (GFP) or Cre-recombinase (Cre) under the control of 2.6 kb of pig DMRT1 5' flanking sequences (pDMRT1p-GFP and pDMRT1p-Cre, respectively). Within the pDMRT1p-GFP positive mice, GFP expression was observed in the XY genital ridge by embryonic day 11.5 (e11.5) and remained detectable during testis embryonic development to birth. GFP expression was restricted within testis cords as soon as cords were detectable. No fluorescence was observed in developing ovaries, although more sensitive RT-PCR analysis revealed transgene expression in embryonic ovaries from e13.5 to e15.5. RT-PCR performed on fluorescent activated cell sorter (FACS)-purified GFP cells from e14.5, e17.5, and e19.5 developing testis showed that GFP expression was restricted to cells expressing the endogenous mouse Dmrt1. GFP cells also expressed Mis and Oct4, showing that the transgene is expressed in both Sertoli cell and germ cell compartments. In postnatal testis, transgene expression was detectable by GFP fluorescence from P0 to P21 in mice heterozygous for the transgene and through adulthood in mice homozygous for the transgene. In pDMRT1p-Cre positive mice, Cre expression was detected within the genital ridges of both XY and XX embryos. We conclude that DMRT1 regulatory mechanisms during sexual differentiation are functionally conserved across mammalian evolution. The transgenic mouse lines described should provide useful marker systems for studies involving Dmrt1 gene expression during sex differentiation.

5' Flanking Region↗