Differences due to collimator blurring in cardiac images with use of circular and elliptic camera orbits.

BACKGROUND: In cardiac imaging systems, an elliptic acquisition orbit about the patient can be used to enhance resolution of single photon emission computed tomography (SPECT) images by minimizing the distance between the object imaged and the rotating detector system. In this study artifacts from images acquired with the standard circular acquisition are compared with those acquired with various elliptic acquisitions. METHODS AND RESULTS: With the use of elliptic camera orbits of different eccentricities, simulated projection data were generated from a slice through the left ventricle (LV). The projection data included a simulation of the degradation due to the depth-dependent response of the collimator. As is common in many clinical systems, SPECT images were reconstructed with the standard filtered backprojection algorithm without correction for the collimator response. When the ratio of the major-to-minor axis of the acquisition arc is changed from 1 (circular) to 1.5 (elliptic), reconstructed SPECT images show an additional loss of counts (about 10%) in the apical region of the LV. The severity of the apical defect is also dependent on the starting angle of the acquisition arc. When the starting angle is changed from 0 degrees (detector parallel to the major axis of the LV) to 60 degrees, the ratio between the minimum count in the apical region and the maximum count in the left ventricular myocardial wall decreases by as much as 20%. CONCLUSIONS: SPECT image artifacts from elliptic acquisitions are significantly more severe than those from circular acquisitions. Because of the significant difference in images reconstructed from circular and elliptic acquisitions, standardized normal files acquired from circular acquisitions should not be used for comparisons with patient data acquired from elliptic acquisitions.

Hybrids monosomal for human chromosome 5 reveal the presence of a spinal muscular atrophy (SMA) carrier with two SMN1 copies on one chromosome.

We have analyzed the survival motor neuron gene (SMN1) dosage in 100 parents of children with homozygous SMN1 deletions. Of these parents, 96 (96%) demonstrated the expected one-copy SMN1 carrier genotype. However, four parents (4%) were observed to have a normal two-copy SMN1 dosage. The presence of two intact SMN1 genes in the parent of an affected child indicates either the occurrence of a de novo mutation event or a situation in which one chromosome has two copies of SMN1, whereas the other is null. We have separated individual chromosomes from two of these parents with two-copy SMN1 dosage by somatic cell hybridization and have employed a modified quantitative dosage assay to provide direct evidence that one parent is a two-copy/ zero-copy SMN1 carrier, whereas the other parent had an affected child as the result of a de novo mutation. These findings are important for assessing the recurrence risk of parents of children with spinal muscular atrophy and for providing accurate family counseling.

A generalized interpolative vector quantization method for jointly optimal quantization, interpolation, and binarization of text images.

This paper presents an approach for the effective combination of interpolation with binarization of gray level text images to reconstruct a high resolution binary image from a lower resolution gray level one. We study two nonlinear interpolative techniques for text image interpolation. These nonlinear interpolation methods map quantized low dimensional 2 x 2 image blocks to higher dimensional 4 x 4 (possibly binary) blocks using a table lookup operation. The first method performs interpolation of text images using context-based, nonlinear, interpolative, vector quantization (NLIVQ). This system has a simple training procedure and has performance (for gray-level high resolution images) that is comparable to our more sophisticated generalized interpolative VQ (GIVQ) approach, which is the second method. In it, we jointly optimize the quantizer and interpolator to find matched codebooks for the low and high resolution images. Then, to obtain the binary codebook that incorporates binarization with interpolation, we introduce a binary constrained optimization method using GIVQ. In order to incorporate the nearest neighbor constraint on the quantizer while minimizing the distortion in the interpolated image, a deterministic-annealing-based optimization technique is applied. With a few interpolation examples, we demonstrate the superior performance of this method over the NLIVQ method (especially for binary outputs) and other standard techniques e.g., bilinear interpolation and pixel replication.

Control of alternative behavioral states by serotonin in Caenorhabditis elegans.

Serotonin has been implicated in the regulation of a wide range of brain functions involving alternative behavioral states, including the control of mood, aggression, sex, and sleep. Here, we report that in the nematode Caenorhabditis elegans, serotonin controls a switch between two distinct, on/off states of egg-laying behavior. Through quantitative analysis of the temporal pattern of egg-laying events, we determined that egg laying can be modeled as a novel random process, in which animals fluctuate between discrete behavioral states: an active state, during which eggs are laid in clusters, and an inactive state, during which eggs are retained. Single-cell ablation experiments indicate that two pairs of motor neurons, HSNL/HSNR and VC4/VC5, can induce the active phase by releasing serotonin. These neurons also release acetylcholine, which appears to trigger individual egg-laying events within the active phase. Genetic experiments suggest that determination of the behavioral states observed for C. elegans egg laying may be mediated through protein kinase C-dependent (PKC-dependent) modulation of voltage-gated calcium channels.

Nonexpansive pyramid for image coding using a nonlinear filterbank.

A nonexpansive pyramidal decomposition is proposed for low-complexity image coding. The image is decomposed through a nonlinear filterbank into low- and highpass signals and the recursion of the filterbank over the lowpass signal generates a pyramid resembling that of the octave wavelet transform. The structure itself guarantees perfect reconstruction and we have chosen nonlinear filters for performance reasons. The transformed samples are grouped into square blocks and used to replace the discrete cosine transform (DCT) in the Joint Photographic Expert Group (JPEG) coder. The proposed coder has some advantages over the DCT-based JPEG: computation is greatly reduced, image edges are better encoded, blocking is eliminated, and it allows lossless coding.

Human T-lymphocyte serine proteases (granzymes) 1, 2, and 3 mediated DNA fragmentation in susceptible target cells.

We reported the characterization of three serine proteases (granzymes 1, 2, and 3) from human cytotoxic T lymphocytes. In this study, human granzymes 1, 2, and 3 were purified from the cytoplasmic granules of lymphokine activated killer (LAK) cells by gel filtration and cation exchange chromatography. Human perforin was purified by phenyl superose and heparin-agarose chromatography. Each purified granzyme was used with purified perforin to study DNA fragmentation in target cells of both human and murine origin. As measured by agarose gel electrophoresis and [125I]dUrd assay, the granzymes induced oligonucleosomal DNA fragmentation and [125I]dUrd release respectively from various target cells. Murine target cells were generally more susceptible to nuclear DNA release than were human targets. Both enzyme activity and nuclear DNA breakdown were significantly inhibited by 3,4-dichloroisocoumarin (DCI) or by heat inactivation of each granzyme. Perforin alone or granzyme alone failed to fragment nuclear DNA in various target cells. We conclude that human granzymes are an important family of effector molecules that with perforin induce DNA fragmentation in susceptible target cells.

Detection of perforin in human peritoneal fluid T-lymphocytes.

OBJECTIVE: Perforin is a specific marker of functionally active cytotoxic T-lymphocytes (CTLs) and natural killer (NK) cells. The purpose of this study was to detect perforin-positive lymphocytes in ascites secondary to various gynecologic malignancies and nonneoplastic conditions. STUDY DESIGN: Fifty-three unselected peritoneal fluid specimens submitted for cytopathologic diagnosis were used. A monoclonal antibody to human perforin was used to examine its expression in mononuclear cells from ascites specimens using a standard immunoperoxidase technique. RESULTS: Strong perforin expression by 15-30% of mononuclear cells was detected in 10 of the 13 patients with severe alcoholic hepatitis, 3 of the 5 patients with chronic active hepatitis without cirrhosis and 1 patient with an autoimmune disorder of unknown etiology. The lymphocytes showed variable positivity for T cell markers (CD2, CD4, CD8 and CD56). Perforin was not detected in ascites specimens obtained from patients with such nonneoplastic disorders as cirrhosis or end stage renal or cardiac failure. Similarly, ascites specimens from patients with various gynecologic malignancies were negative for perforin-positive lymphocytes. CONCLUSION: The detection of cytotoxic lymphocytes in peritoneal fluid obtained from patients with liver injury may have implications for the pathogenesis of this disease.

Template matching based on a grayscale hit-or-miss transform.

This paper introduces a class of rank-order-based template matching criteria that are multiplier-free and independent of the dc variations of the image. The core component of these criteria is a grayscale morphological hit-or-miss transform (GHMT). Experimental results show that the GHMT features sharp and robust indications in the presence of Gaussian noise. The idea of the GHMT is used to develop more general forms of matching criteria that are robust to both Gaussian and impulsive noises.

Scientific bases of human-machine communication by voice.

The scientific bases for human-machine communication by voice are in the fields of psychology, linguistics, acoustics, signal processing, computer science, and integrated circuit technology. The purpose of this paper is to highlight the basic scientific and technological issues in human-machine communication by voice and to point out areas of future research opportunity. The discussion is organized around the following major issues in implementing human-machine voice communication systems: (i) hardware/software implementation of the system, (ii) speech synthesis for voice output, (iii) speech recognition and understanding for voice input, and (iv) usability factors related to how humans interact with machines.

Rapid detection of Serpulina hyodysenteriae in diagnostic specimens by PCR.

A PCR assay for the detection of Serpulina hyodysenteriae in diagnostic specimens was developed on the basis of sequence analysis of a recombinant clone designated pRED3C6. Clone pRED3C6, which contained a 2.3-kb DNA fragment unique to S. hyodysenteriae, was identified by screening a plasmid library of S. hyodysenteriae isolate B204 genomic DNA in Escherichia coli by colony immunoblot with the mouse monoclonal antibody 10G6/G10, which was produced against cell-free supernatant antigens from the same isolate. Southern blot analysis of HindIII-digested genomic DNA of S. hyodysenteriae serotypes 1 through 7 and of four weakly beta-hemolytic intestinal spirochetes, including Serpulina innocens, with the 2.3-kb DNA fragment of pRED3C6 indicated that the cloned sequence was present exclusively in the seven serotypes of S. hyodysenteriae. An oligonucleotide primer pair for PCR amplification of a 1.55-kb fragment and an internal oligonucleotide probe were designed and synthesized on the basis of sequence analysis of the 2.3-kb DNA fragment of pRED3C6. Purified genomic DNAs from reference isolates of S. hyodysenteriae serotypes 1 through 9, S. innocens, weakly beta-hemolytic intestinal spirochetes belonging to genotypic groups distinct from those of reference Serpulina spp., other cultivable reference isolates of the order Spirochaetales, and enteric bacteria including Escherichia coli, Salmonella spp., Campylobacter spp., and Bacteroides vulgatus were amplified with the oligonucleotide primer pair in a hot-start PCR. The 1.55-kb products were obtained only in the presence of genomic DNA from each of the nine serotypes of S. hyodysenteriae. The specificity of the 1.55-kb products for S. hyodysenteriae was confirmed on the basis of production of a restriction endonuclease pattern of the PCR products identical to the predicted restriction map analysis of pRED3C6 and positive hybridization signal with the S. hyodysenteriae-specific internal oligonucleotide probe. By using total DNA obtained from normal swine feces inoculated with decreasing concentrations of S. hyodysenteriae cells, the sensitivity of the PCR assay was calculated to be between 1 and 10 organisms per 0.1 g of feces. The PCR assay was 1,000 times more sensitive than conventional culture of dysenteric feces on selective medium. There was complete agreement between the results of PCR assays and anaerobic culture on selective agar medium with diagnostic specimen (n = 9) obtained from six farms on which there were cases with clinical signs suggestive of swine dysentery. Detection of S. hyodysenteriae by PCR amplification of DNA has great potential for rapid identification of S. hyodysenteriae in diagnostic specimens.

Characterization of normal human cells by pyrolysis gas chromatography mass spectrometry.

Differentiation of normal human cells has been accomplished by pyrolysis gas chromatography mass spectrometry. Normal cells from human kidney, spleen, liver and brain tissues have been pyrolyzed and the products chromatographically separated and characterized by mass spectrometry. Molecular pyrolysis products giving rise to the characteristic pyro-mass chromatograms include, but are not limited to, alkenes, alkanes, nitriles and various ring compounds. Single ion mass chromatograms as well as multiple ion mass chromatograms have been used to explore the characteristic differences between various tissue materials. A dynamic computer methodology for comparing pyro-mass chromatograms has been developed for use in automatic identification and classification of the human cellular material.