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PubMed1992

[Spinal cord tumors and tumors causing spinal cord compression in the aged].

In incipient disorders of gait in old people frequently the possible presence of a benign spinal tumour is not taken into account. The patients are treated for assumed common complaints associated with old age. Thus much valuable time is lost before the only correct approach--surgery--is made. The author describes in her own group of patients early symptoms of spinal compression and supplements data by case-histories. The results of surgery in a group of patients with benign spinal tumours depended on the degree of spinal compression as well as on the duration of this compression. In the group of epidural secondary spinal tumours the results of surgery were not satisfactory.

Aged↗
PubMed2002

Neuroradiologic screening in normal-pressure glaucoma: study results and literature review.

PURPOSE: To determine if there was an increased prevalence of intracranial compressive lesions in patients with clinically diagnosed normal-pressure glaucoma compared with a group of patients with progressive primary open-angle glaucoma. PATIENTS AND METHODS: In a prospective, comparative, observational case series, the authors performed cranial magnetic resonance imaging in patients with consecutively diagnosed normal-pressure glaucoma (n = 62) and progressive primary open-angle glaucoma with controlled intraocular pressures (n = 70). The prevalence of intracranial compressive lesions, demographic data, and clinical characteristics were compared between both groups. RESULTS: Four of the 62 (6.5%) patients with normal-pressure glaucoma had clinically relevant intracranial compressive lesions involving the anterior visual pathway, compared with none of the 70 patients with primary open-angle glaucoma (P = 0.039). CONCLUSIONS: Intracranial compressive lesions are an important diagnostic consideration in the workup of normal-pressure glaucoma.

Adenoma↗
PubMed1987

Personal reflections on the nature of intelligence in humans and machines.

Computers, the human mind, and social systems have common problems of inadequate memory and insufficient data manipulation speed. In each of these domains, information compression techniques have evolved to reduce storage and processing needs. Among the techniques for information compression, coding of information in procedures stands out as exceptionally powerful. Procedural information coding also gives rise to behavior that may be defined as intelligent. It is found in the human mind, in machines and in social systems. Its use in human thought is aided by language development which promotes regular review of abstract procedures. A practical consequence of better understanding of procedural information coding is the possibility of training people to exhibit greater mental capacity, a controversial possibility. This paper explores the impact of data processing resource limitations, data compression and procedural thinking in men and machines.

Artificial Intelligence↗
PubMed1995

Metastatic paraganglioma causing spinal cord compression.

SUMMARY OF BACKGROUND DATA: Paragangliomas are neoplasms that arise from the autonomic nervous system-associated paraganglia. Most often they are benign tumors. However, infrequently they have been reported to metastasize. Involvement of the spine is rare and usually is intradural at the level of the cauda equina. OBJECTIVES: The authors report two cases of metastatic paraganglioma to the spine, both of which resulted in myelopathy from extradural spinal cord compression. Also provided is a review of the literature. CONCLUSIONS: Paragangliomas rarely metastasize to the spine. Management of the two reported patients involved spinal cord decompression followed by spinal stabilization procedures. Long-term ambulatory status was maintained in both patients. Radiation therapy may be an important adjunctive treatment after surgical removal of these tumors.

Adult↗
PubMed2005

Course of spinal solitary osteochondromas.

STUDY DESIGN: Six spinal solitary osteochondromas. OBJECTIVES: To evaluate the course of spinal cord compression after surgery, and the risk of local recurrence and malignant transformation, based on the present series and cases reported in the literature. SUMMARY OF BACKGROUND DATA: Spinal cord compression by a solitary osteochondroma is rare. Little is known concerning neurologic improvement after decompression of the spinal cord or the risk of recurrence or malignant transformation of spinal solitary osteochondroma, because most of the cases reported are isolated. METHODS: Clinical history, plain radiographs, pathologic features, computed tomographic studies, and magnetic resonance imaging were reviewed. Five patients underwent long-term follow-up physical examination and computed tomography for an average of 6 years (range, 2-12 years) after surgical treatment. The literature was reviewed for solitary osteochondroma with spinal cord compromise, recurrent solitary osteochondroma, or solitary osteochondroma in the process of sarcomatous transformation. RESULTS: In the present study, two of the six patients experienced spinal cord compromise. Neurologic deficits improved after surgery. None of the patients had local recurrence or malignant transformation at follow-up observation. Including these two patients, the authors found 62 cases of solitary osteochondroma with spinal cord compromise in the literature. Overall, three patients died, eight did not improve, and 48 (81%) experienced regression of the neurologic deficit after surgical decompression. Among the 150 cases of solitary osteochondroma the authors found in the literature, there were six cases (4%) of local recurrence and four cases (2.7%) of malignant transformation. CONCLUSIONS: Surgical treatment improves neurologic deficit in more than 80% of cases of spinal cord compromise caused by solitary osteochondroma. The risk of recurrence or sarcomatous transformation justifies clinical and radiologic follow-up review.

Adolescent↗
PubMed1996

Compression of digital coronary angiograms does not affect visual or quantitative assessment of coronary artery stenosis severity.

Digital coronary angiographic techniques are now widely used in many cardiac catheterization laboratories. However, the full potential of digital imaging technology remains to be achieved because of its enormous storage and exchange requirements. Compression of digital imaging data allows a reduction in the volume of data so that storage and transmission are more efficient and cost-effective. Three angiographers reviewed the original and compressed formats of 96 coronary angiographic sequences in a blinded fashion to assess coronary lesion severity. Compression was achieved using the Joint Photographic Experts Group (JPEG) standard, which resulted in a compression ratio of approximately 15:1. The original format was reviewed in a blinded fashion a second time to assess for intraobserver variability of similar formats. Lesion severity was graded in quartiles. Coronary stenosis >50% was considered "significant." In parallel, the reproducibility of quantitative coronary angiographic (QCA) measurements of coronary artery dimensions was also evaluated. For the visual assessment of lesion severity in the compressed versus original formats, kappa=0.52, suggesting moderate agreement. When lesions were assessed as significant versus "insignificant," however, kappa=0.88, suggesting excellent agreement. In the 2 separate readings of the original data formats, kappa=0.44 for assessment of lesion severity by quartiles and kappa=0.72 for lesions assessed as significant versus insignificant. Analysis of the compressed versus original data sets using QCA resulted in an excellent correlation for the measurement of lesion severity (r=0.99). The correlation was equally strong when the original format was analyzed sequentially (r=0.98). Lossy JPEG (15:1) compression is a valid means for reducing storage and exchange requirements of coronary angiographic data. The variability in assessing lesion severity between the original and compressed formats is comparable to the reported variability in visual assessment of lesion severity in sequential analysis of cine film.

Angiography, Digital Subtraction↗
PubMed1986

An algorithm to manage variable-length records for highly portable clinical data base systems.

An algorithm to archive patient data at free size in disk storage is presented. A record, assumed to be a character string such as an ASCII-coded text, is compressed and divided into fixed-length blocks. One block consists of a data field and a pointer field, and the blocks comprising a record are chained with pointers forwardly. A head pointer of each record is sequentially saved on a separate file. The data compression is performed as follows: if the same character code appears more than twice in succession, we count the number of the repetitions and save it with initial two characters. The algorithms for fetching, re-saving, and purging a record are also presented. These were implemented in FORTRAN77 and tested for performance using a practical patient data file. As the algorithm allows highly flexible record manipulation and can easily be implemented in conventional programming languages, it will make a useful tool for constructing a portable data base management system.

Evaluation Studies as Topic↗
PubMed2006

Rate-distortion analysis of motion-compensated rate scalable video.

Generally speaking, rate scalable video systems today are evaluated operationally, meaning that the algorithm is implemented and the rate-distortion performance is evaluated for an example set of inputs. However, in these cases it is difficult to separate the artifacts caused by the compression algorithm and data set with general trends associated with scalability. In this paper, we derive and evaluate theoretical rate-distortion performance bounds for both layered and continuously rate scalable video compression algorithms which use a single motion-compensated prediction (MCP) loop. These bounds are derived using rate-distortion theory based on an optimum mean-square error (MSE) quantizer, and are thus applicable to all methods of intraframe encoding which use MSE as a distortion measure. By specifying translatory motion and using an approximation of the predicted error frame power spectral density, it is possible to derive parametric versions of the rate-distortion functions which are based solely on the input power spectral density and the accuracy of the motion-compensated prediction. The theory is applicable to systems which allow prediction drift, such as the data-partitioning and SNR-scalability schemes in MPEG-2, as well as those with zero prediction drift such as fine granularity scalability MPEG-4. For systems which allow prediction drift we show that optimum motion compensation is a sufficient condition for stability of the decoding system.

Algorithms↗
PubMed2002

Pressure-induced structural changes in liquid SiO2 from Ab initio simulations.

First-principles molecular dynamics simulations at constant pressure have been used to investigate the mechanisms of compression of liquid SiO2. Liquid SiO2 is found to become denser than quartz at a pressure of about 6 GPa, in agreement with extrapolations of lower pressure experimental data. The high compressibility of the liquid is traced to medium-range changes in the topology of the atomic network. These changes consist in an increase of network connectivity caused by the pressure-induced appearance of coordination defects.

Journal Article↗
PubMed1987

Data acquisition system for maximum-likelihood analysis of electron microscopic autoradiographs.

EMAMAP is a program for the data acquisition phase of maximum-likelihood analysis of electron microscope autoradiographs. This program is written in C and has been implemented on a Masscomp MC-500 which supports a graphics processor and a digitizing tablet. The image analysis is automated at a low level: the program operator outlines the edges of the structures of interest using the digitizing tablet, while contiguous regions formed by closed contours are automatically filled by the software. The resulting image is compressed for efficient storage by a quadtree encoding technique for which data compression ratios of greater than 25:1 have been achieved. In practical terms, this implies that the data from a typical experiment of 50 autoradiographs could be stored on a single floppy disk. The system is currently in use for acquiring actual biological experimental data.

Autoradiography↗
PubMed2005

Structure and biomechanical properties of the trachea of the striped dolphin Stenella coeruleoalba: evidence for evolutionary adaptations to diving.

This study analyzes the structure and mechanical properties of the trachea of the striped dolphin Stenella coeruleoalba, one of the most common cetacean species. The cetacean trachea is made up of closed or semiclosed cartilaginous rings without a paries membranaceus. Our results indicate that the inner lining of the trachea contains erectile tissue in which several venous lacunae permeate the mucosa. We also observed and described the presence of peripheral neurons containing nitric oxide along the rim of the venous lacunae. Data obtained from compression and tensile tests and comparison with the pig and goat tracheas indicate a higher stiffness and a different, higher breaking point for the dolphin trachea. On the whole, our data suggest that the trachea of the striped dolphin possesses structural properties that allow rapid filling with blood, possibly in relation to dive activities, and also allow modifications due to increased pressure and immediate return to the original shape without risks of permanent bending or rupture, as would happen in a terrestrial mammal. As the organ undergoes intense pressure difference during descent to optimal foraging depth and subsequent rapid ascent to surface, especially in deep dives of hundreds of meters, the specific structural and biomechanical peculiarities of the trachea of the striped dolphin may represent an evolutionary adaptation to life in the water and to diving.

Animals↗
PubMed2006

Posterior spinal cord compression: outcome and results.

STUDY DESIGN: Prospective, comparative study of neurologic outcome in patients with posterior extradural cord compression. OBJECTIVE: To compare the results of surgical decompression in patients presenting with neurologic deficit due to posterior element tuberculosis with those due to other causes. SUMMARY OF BACKGROUND DATA: Posterior cord compression is a relatively uncommon entity with not much literature published on it. METHODS: Over a period of 5 years, 14 patients with extradural posterior cord compression with neurologic deficit were divided into two etiologic groups: 9 patients had Koch's and 5 had other pathologies. All these cases were surgically decompressed posteriorly and the results compared. RESULTS: While results of surgery in patients with Koch's were good, with 7 of the 9 patients showing full recovery, outcome in patients with compression due to other causes (tumor/pyogenic infection) was not very satisfactory even after adequate mechanical decompression, with 3 of the 5 cases remaining paraplegic even after surgery. CONCLUSION: Posterior cord compression due to nontuberculous causes frequently mimics the picture of Koch's both clinically and radiologically. Prognosis of surgical decompression is good in tuberculous compression but not in other cases.

Abscess↗
PubMed1996

Increased resistance to acute compression injury in chronically compressed spinal nerve roots. An experimental study.

STUDY DESIGN: Nerve conduction velocity was studied in the dog cauda equina subjected to chronic and, 1 week later, additional acute compression. OBJECTIVES: To model the situation of spinal stenosis by first inducing a controlled, chronic compression injury and then to add compression at various pressure levels to the already compressed cauda equina. SUMMARY OF BACKGROUND DATA: Previous models on nerve root and cauda equina compression have analyzed the effects of compression only on noninjured nerves. Clinically, the nerves that are compressed in spinal stenosis already are exposed to chronic compression. METHODS: The cauda equine in the lumbar spine of 10 dogs was first compressed by inflating a plastic balloon, which was placed in the spinal canal, to 10 mm Hg with a viscous substance or leaving it noninflated for control. After 1 week, a second plastic balloon, which was welded together with the first balloon, which had been located in the spinal canal for 1 week, was inflated to 50 or 100 mm Hg for 2 hours with 1.5 hour of recovery, and changes in the nerve conduction velocity were analyzed. Before inflation, baseline data, reflecting the effects of the chronic compression per se, were obtained. RESULTS: After 1 week, the nerve conduction velocity was significantly lower in the compressed cauda equina than in the control series, as an effect of the chronic compression. Additional compression demonstrated that the chronically compressed cauda equina was less susceptible to the compression-induced effects at 100 mm Hg compression. CONCLUSIONS: The data of the present study indicate that chronically compressed nerve roots acquire a tolerance to acute compression, which may indicate that there has been adaptation processes present in the compressed nerve tissue.

Acute Disease↗
PubMed2005

A nonlinear biphasic viscohyperelastic model for articular cartilage.

Experiments on articular cartilage have shown nonlinear stress-strain curves under finite deformations as well as intrinsic viscous effects of the solid phase. The aim of this study was to propose a nonlinear biphasic viscohyperelastic model that combines the intrinsic viscous effects of the proteoglycan matrix with a nonlinear hyperelastic constitutive equation. The proposed equation satisfies objectivity and reduces for uniaxial loading to a solid type viscous model in which the actions of the springs are represented by the hyperelastic function proposed by Holmes and Mow [1990. J. Biomechanics 23, 1145-1156.]. Results of the model, that were efficiently implemented in an updated Lagrangian algorithm, were compared with experimental infinitesimal data reported by DiSilverstro and Suh [2001. J. Biomechanics 34, 519-525.] and showed acceptable fitting for the axial force (R(2)=0.991) and lateral displacement (R(2)=0.914) curves in unconfined compression as well as a good fitting of the axial indentation force curve (R(2)=0.982). In addition, the model showed an excellent fitting of finite-deformation confined compression stress relaxation data reported by Ateshian et al. [1997. J. Biomechanics 30, 1157-1164.] and Huang et al. [2005. J. Biomechanics 38, 799-809.] (R(2)=0.993 and R(2)=0.995, respectively). The constitutive equation may be used to represent the mechanical behavior of the proteoglycan matrix in a fiber reinforced model of articular cartilage.

Animals↗
PubMed2006

Cochlear implant speech processor placement and compression effects on sound sensitivity and interaural level difference.

The purpose of this investigation was to determine the impact of commonly recommended cochlear implant (CI) speech processor placements on microphone output both with and without single channel front-end compression. The impact of this compression use on interaural level difference (ILD) magnitude was also evaluated for the ear-level position. Finally, pilot localization data collected with and without single channel front-end compression was collected on seven bilateral cochlear implant recipients. The results revealed that differences in signal audibility due to clinical placement of CI speech processors in ear, shoulder, and collar positions can at least partially be offset through the use of front-end compression. These data also revealed that compression impacted ILD cues. Preliminary data indicated that some bilaterally implanted subjects were able to take advantage of the enhanced ILD cues when compression was turned off, while other bilaterally implanted subjects did not localize better in the compression-off condition.

Acoustic Stimulation↗
PubMed2001

Compact storage of medical images with patient information.

Digital watermarking is a technique of hiding specific identification data for copyright authentication. This technique is adapted here for interleaving patient information with medical images to reduce storage and transmission overheads. The text data are encrypted before interleaving with images to ensure greater security. The graphical signals are compressed and subsequently interleaved with the image. Differential pulse-code-modulation and adaptive-delta-modulation techniques are employed for data compression, and encryption and results are tabulated for a specific example.

Computer Security↗
PubMed1996

Rehabilitative functional outcome of patients with neoplastic spinal cord compressions.

OBJECTIVE: To examine functional outcome and descriptive data of individuals with neoplastic spinal cord compression admitted to a rehabilitation unit. DESIGN: A 5-year review of consecutive patients admitted to a spinal cord injury rehabilitation unit with a diagnosis of neoplastic spinal cord compression. SETTING: A tertiary university medical center. PATIENTS: Thirty-two consecutive patients with neoplastic spinal cord compression who met standard rehabilitation admission criteria and had a prognosis of no less than 3 months' survival. MAIN OUTCOME MEASURES: Functional data, including length of stay, functional outcomes (utilizing Functional Independent Measurement scores in mobility and self-care), bladder management, and disposition. RESULTS: Lung (28%) and prostate (17%) were the most common tumor types, and upper thoracic (40%) was the most common level of spinal cord involvement. Functional Independent Measure improvements were found in all areas, with significant improvements (paired t test, p < .005) noted in the areas of upper and lower extremity dressing, grooming, toilet and tub transfers, wheelchair use and transfers, ambulation, and stair climbing. Average length of rehabilitation stay was 27 days, and 84% of the patients were discharged to home. Seventy-five percent of the 20 responders to a follow-up survey had maintained or improved their discharge functional abilities at 3 months after discharge. CONCLUSIONS: These data suggest that in individuals with spinal cord compression caused by neoplastic invasion, functional improvements in mobility and self-care can be achieved and maintained for at least 3 months after discharge.

Activities of Daily Living↗
PubMed2025

Evaluation of sequencing reads at scale using rdeval.

MOTIVATION: Large sequencing datasets are being produced and deposited into public archives at unprecedented rates. The availability of tools that can reliably and efficiently generate and store sequencing read summary statistics has become critical. RESULTS: As part of the effort by the Vertebrate Genomes Project (VGP) to generate high-quality reference genomes at scale, we sought to address the community's need for efficient sequence data evaluation by developing rdeval, a standalone tool to quickly compute and interactively display sequencing read metrics. Rdeval can either run on the fly or store key sequence data metrics in tiny read 'snapshot' files. Statistics can then be efficiently recalled from snapshots for additional processing. Rdeval can convert fa*[.gz] files to and from other popular formats including BAM and CRAM for better compression. Overall, while CRAM achieves the best compression, the gain compared to BAM is marginal, and BAM achieves the best compromise between data compression and access speed. Rdeval also generates a detailed visual report with multiple data analytics that can be exported in various formats. We showcase rdeval's functionalities using long-read data from different sequencing platforms and species, including human. For PacBio long-read sequencing, our analysis shows dramatic improvements in both read length and quality over time, as well as the benefit of increased coverage for genome assembly, though the magnitude varies by taxa. AVAILABILITY AND IMPLEMENTATION: Rdeval is implemented in C++ for data processing and in R for data visualization. Precompiled releases (Linux, MacOS, Windows) and commented source code for rdeval are available under MIT license at https://github.com/vgl-hub/rdeval. Documentation is available on ReadTheDocs (https://rdeval-documentation.readthedocs.io). Rdeval is also available in Bioconda and in Galaxy (https://usegalaxy.org). An automated test workflow ensures the consistency of software updates.

Software↗