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PubMed2006

[Study of color blood image segmentation based on two-stage-improved FCM algorithm].

This paper introduces a new method for color blood cell image segmentation based on FCM algorithm. By transforming the original blood microscopic image to indexed image, and by doing the colormap, a fuzzy apparoach to obviating the direct clustering of image pixel values, the quantity of data processing and analysis is enormously compressed. In accordance to the inherent features of color blood cell image, the segmentation process is divided into two stages. (1)confirming the number of clusters and initial cluster centers; (2) altering the distance measuring method by the distance weighting matrix in order to improve the clustering veracity. In this way, the problem of difficult convergence of FCM algorithm is solved, the iteration time of iterative convergence is reduced, the execution time of algarithm is decreased, and the correct segmentation of the components of color blood cell image is implemented.

Algorithms↗
PubMed2006

Design variables for mechanical properties of bone tissue scaffolds.

The reconstruction of segmental defect in long bone is a clinical challenge. Multiple surgeries are typically required to restore the structure and function of the affected defect site. In order to overcome this defect a biodegradable bone tissue engineering scaffold is used. This scaffold acts as a carrier of proteins and growth factors, while also supporting the load that the bone would normally sustain, until the natural bone can regenerate in its place. Work was done to optimize an existing solid free-form scaffold design. The goal of the optimization was to increase the porosity of the scaffold while maintaining the strength of a previously-tested prototype design. With this in mind, eight new designs were created. These designs were drawn using CAD software and then through the use of finite element analysis the theoretical ultimate compressive strength of each design was obtained. Each scaffold design was constructed by casting a thermal-curable poly(propylene fumarate)/tricalcium phosphate (PPF/TCP) suspension into wax molds fabricated on inkjet printing rapid prototyping machine. The constructs were then experimentally tested by applying a uniaxial compressive load. The theoretical and experimental values of ultimate compressive strength and specific strength of each design were compared. Theoretically, the best scaffold design produced from this work improved upon the current design by increasing the porosity by 46% and also increasing the ultimate compressive strength by 27%. The experimental data was found to match the theoretical strength in four designs, but deviate from the theoretical strength in five designs. The reasons for the deviations and their relation to the rapid prototyping manufacturing technique were discussed. The results of this work show that it is possible to increase the porosity and strength of a bone tissue engineering scaffold through simple iterations in architectural design.

Biocompatible Materials↗
PubMed1989

[A modified unit for detecting sleep apnea].

A comprehensive diagnostic work-up of patients with a suspected sleep apnea syndrome must include conventional polysomnographic monitoring during the night. On account of the considerable staff and technical requirement, however, this definitive diagnostic measure is not suitable for use as a screening programme. For this reason we undertook to develop a device for the computer-aided recording of sleep apnea. The heart of the unit is a 65816 microprocessor with an address capacity of 16 Mbytes. The oro-nasal airflow is recorded with the aid of thermistors, and, after digital filtering, the respiratory rate is continuously recorded on the basis of this signal. Continuous recording of the heart rate and oxygen saturation, is also effected, the recorded data being stored in the microprocessor. On conclusion of the data acquisition phase, evaluation and a compressed display is shown on any conventional personal computer. Our preliminary experience reveals that the algorithm employed is extremely reliable for the detection of respiration rate and apnea, even in the presence of unfavourable signal forms. Clinically relevant deviations from manual evaluation do not occur. As was to be expected, processing of the signals for heart rate and oxygen saturation presented no problems.

Humans↗
PubMed1989

[Quantitative evaluation of bone mineral contents of hand bone using CR technique].

We evaluated the clinical applicability of a matrix compression technique on computed radiography (CR) data for quantitative measurements of bone mineral content of hand bones. Similar results were obtained compared to those obtained by the conventional microdensitometry (MD) technique. This CR technique which uses imaging plates should take the place of the normal MD technique due to the fact that it provides for the reduction of exposure dosage.

Absorptiometry, Photon↗
PubMed1989

Sound and vibration transmission in tissues.

Sound pressure levels measured inside a body must account for the acoustic impedance of the medium in order to obtain information on acoustic intensity. However, there is some uncertainty about the acoustic signals that reach and stimulate the fetal ear. Large wavelengths of frequencies in tissue in the human audible range suggest that the fetal ear will be in the near field of signals transmitted across the air/tissue interface or from an electrolarynx vibrator over a large portion of the frequency range. There are numerous physical mechanisms which effect high-frequency signals in transmission. Vibrational shear waves generated by electrolarynx activation on the skin will influence the fetal sound environment. Further research is required to fully understand the significance of measured signals when both compression and shear waves are present. Data in the frequency domain could be misconstrued, unless peculiarities of some acoustical measuring systems are understood.

Acoustics↗
PubMed1985

Supine position in labor and associated fetal heart rate changes.

Presented is an investigation of the relationship of fetal heart rate (FHR) deceleration and position of the patient in labor. In a group of 902 laboring patients, 126 (14%) demonstrated late decelerations. Of the 126, 24 (19%) patients demonstrated late decelerations in the supine position only. These occurred during uterine contractions and were associated with reduced femoral arterial blood pressure and amplitude of the capillary pulse of the big toe. A drop in capillary blood pH of the fetal scalp could also be demonstrated. These effects reproducibly appeared and disappeared when supine and lateral positions were alternated. These data would suggest that maternal aortic compression by the pregnant uterus plays a role in the etiology of fetal stress as expressed by changes in fetal heart rate and acid base balance. This effect can be evaluated and monitored simply by recording the pulse pressure of the big toe and femoral arterial pressure. These atraumatic procedures can be applied to any patient.

Aorta, Abdominal↗
PubMed2003

Prolonged spinal loading induces matrix metalloproteinase-2 activation in intervertebral discs.

STUDY DESIGN: An established in vivo mouse model of compression-induced disc degeneration was used to investigate the effects of load on matrix catabolism. OBJECTIVES: To determine whether matrix metalloproteinase-2 expression in discs is modulated by mechanical load and to characterize the regulation of matrix metalloproteinase-2 activity. SUMMARY OF BACKGROUND DATA: We have previously shown that static compression of discs elicits changes in tissue architecture consistent with those seen with degeneration. Evidence in the literature demonstrates the existence of matrix metalloproteinases in both healthy and pathologic discs and suggests that mechanical load may influence matrix metalloproteinase expression and activity. METHODS: Static compression was applied to mouse coccygeal discs in vivo for 1, 4, or 7 days, with adjacent discs serving as sham control. An activity assay was used to measure concentrations of active and total matrix metalloproteinase-2, and changes in matrix metalloproteinase-2 gene expression relative to beta-actin were assessed by reverse transcriptase-polymerase chain reaction. RESULTS: Although no change was seen relative to sham after 1 day of load, the proportion of total matrix metalloproteinase-2 that was active increased after 4 days. This elevation was sustained through 7 days of compression, with no significant differences in total matrix metalloproteinase-2 concentrations among discs throughout the range of time points examined. Semiquantitative reverse transcriptase-polymerase chain reaction demonstrated no significant changes in matrix metalloproteinase-2 gene expression at 1 day or 4 days. CONCLUSIONS: In this model, regulation of matrix metalloproteinase-2 activity occurs primarily through enhanced molecular activation of the proenzyme rather than through elevated gene expression or translation. Our results suggest that matrix metalloproteinase-2 may have a role in load-induced changes in disc architecture.

Animals↗
PubMed2006

Multiscale fragile watermarking based on the Gaussian mixture model.

In this paper, a new multiscale fragile watermarking scheme based on the Gaussian mixture model (GMM) is presented. First, a GMM is developed to describe the statistical characteristics of images in the wavelet domain and an expectation-maximization algorithm is employed to identify GMM model parameters. With wavelet multiscale subspaces being divided into watermarking blocks, the GMM model parameters of different watermarking blocks are adjusted to form certain relationships, which are employed for the presented new fragile watermarking scheme for authentication. An optimal watermark embedding method is developed to achieve minimum watermarking distortion. A secret embedding key is designed to securely embed the fragile watermarks so that the new method is robust to counterfeiting, even when the malicious attackers are fully aware of the watermark embedding algorithm. It is shown that the presented new method can securely embed a message bit stream, such as personal signatures or copyright logos, into a host image as fragile watermarks. Compared with conventional fragile watermark techniques, this new statistical model based method modifies only a small amount of image data such that the distortion on the host image is imperceptible. Meanwhile, with the embedded message bits spreading over the entire image area through the statistical model, the new method can detect and localize image tampering. Besides, the new multiscale implementation of fragile watermarks based on the presented method can help distinguish some normal image operations such as JPEG compression from malicious image attacks and, thus, can be used for semi-fragile watermarking.

Algorithms↗
PubMed2005

An observational study of bispectral index monitoring for out of hospital cardiac arrest.

Cerebral resuscitation is the most important goal of advanced life support. Currently, there are no objective monitoring methods available to gauge the effectiveness of advanced life support on cerebral resuscitation. We assessed the utility of bispectral index (BIS) monitoring during cardiopulmonary resuscitation as a marker of cerebral resuscitation. Twenty one patients with out of hospital cardiac arrest had a BIS monitor applied during the resuscitation, in addition to standard advanced life support. The BIS monitor was also applied to a cadaver to assess the role of artefact. Illustrative data are presented, outlining the process of evaluation undertaken. A major component of the BIS tracing during external chest compressions appears to be due to movement artefact. Our pilot data indicate that with current technology, BIS monitoring is not a clinically reliable marker of the efficacy of external chest compressions.

Adult↗
PubMed2003

Coding of cognitive magnitude: compressed scaling of numerical information in the primate prefrontal cortex.

Whether cognitive representations are better conceived as language-based, symbolic representations or perceptually related, analog representations is a subject of debate. If cognitive processes parallel perceptual processes, then fundamental psychophysical laws should hold for each. To test this, we analyzed both behavioral and neuronal representations of numerosity in the prefrontal cortex of rhesus monkeys. The data were best described by a nonlinearly compressed scaling of numerical information, as postulated by the Weber-Fechner law or Stevens' law for psychophysical/sensory magnitudes. This nonlinear compression was observed on the neural level during the acquisition phase of the task and maintained through the memory phase with no further compression. These results suggest that certain cognitive and perceptual/sensory representations share the same fundamental mechanisms and neural coding schemes.

Action Potentials↗
PubMed2005

Cervical spondylotic myelopathy: 10 years of prospective outcome analysis of anterior decompression and fusion.

BACKGROUND: Fifty-one patients with cervical spondylotic myelopathy (CSM) treated by anterior cervical corpectomy with fusion (ACWF) at our institution were included in a study during a period of 10 years to evaluate neurological, anatomical, and functional outcomes including satisfaction levels. METHODS: We have completed a prospective evaluation of 39 patients with spondylotic myelopathy submitted to ACWF during the period of 1989-2000. The data were analyzed for age, duration of symptoms, severity of preoperative neurological deficit, and single-level or multilevel compressive status looking for possible association with prognostic surrogate data and clinical outcome that were evaluated with the Nurick score and a survey of level of satisfaction. RESULTS: Of the 51 patients, 39 fullfilled the intended follow-up being 28 men (71.8%) and 11 women (28.2%). The average age was 63.5 years. Duration of symptoms ranged from 1 to 240 months (mean, 38.1 months). The mean preoperative Nurick scale score was 2.97; the mean postoperative score was 2.1. The most frequently involved vertebral body was C5 (71.7%). The follow-up period was longer than 18 months for all patients. Postoperative nonneurological complications occurred in 8 patients (15.6%). The mortality rate was 1.9% (n = 1). Postoperative results showed improvement in 25 patients (64.1%), no change in 13 (33.3%), and worsening in 1 (2.6%). The correlation coefficient of preoperative and postoperative Nurick scores was 0.733 (R(2) = 0.53). Of the 39 patients, 31 answered the questionnaire for quality of life-19 (61.2%) were very satisfied, 6 were satisfied (19.35%), and 6 were not satisfied (19.35%). CONCLUSION: Most patients (80.6%) were very satisfied or satisfied with the outcome and would decide again for the surgery (87%) if the results were previously known. Anterior cervical corpectomy with fusion was a reliable and rewarding procedure for CSM, with functional improvement in most patients. Excellent long-term outcome results in cervical fusion can be achieved without the use of hardware instrumentation.

Adult↗
PubMed1995

[Color Doppler-guided compression of pseudoaneurysms after arterial puncture. Early and late results].

Sixteen pseudoaneurysms occurred after 1796 femoral arterial punctures for diagnostic coronary angiography and/or angioplasty, performed between 1. 1. 1993 and 25. 3. 1994. One additional patient with pseudoaneurysm had undergone a femoral arterial puncture at another hospital. Primary colour Doppler-directed compression of the pseudoaneurysm (15-minute compression followed by 10-minute compressions, as needed) was successful in 16 patients. There was one recurrence, after five days, which was successfully and lastingly treated by another compression. Primary thrombosing by compression of the pseudoaneurysm failed in only one patient, but after spontaneous thrombosis achieved by a compression bandage no flow was demonstrable on the following day. Clinical examination and/or colour Doppler sonography was performed on all patients a mean of 84 days (5 days to 6 months) after successful treatment: no recurrence was recorded. There were no significant early or late complications. These data indicate that colour Doppler-monitored compression of femoral-artery pseudoaneurysm can be considered the treatment of choice, with few exceptions, for this not rare complication of arterial catheterization.

Aneurysm, False↗
PubMed1998

The effect of 10 : 1 compression and soft copy interpretation on the chest radiographs of premature neonates with reference to their possible application in teleradiology.

The aim of the study was to assess the potential application of teleradiology in the neonatal intensive care unit (NICU) by ascertaining whether any decrease in conspicuity of anatomic detail or interventional devices in the chest radiographs of premature infants is caused by picture archiving and communication system (PACS)-based soft copy interpretation of 10 : 1 compressed images. One hundred digital chest radiographs of low-birthweight infants were obtained in the NICU using a storage phosphor system. Laser-printed images were interpreted and the data set for each radiograph was then irreversibly compressed by a 10 : 1 ratio. Four radiologists with extensive PACS experience used a five-point grading system to score laser-printed hard copy images for the visibility of six parameters of anatomic landmarks and interventional devices in the chest. Compressed soft copy images displayed on 2K PACS workstation were subsequently scored using the same approach. Statistical manipulation demonstrated no loss of anatomic detail in five of the six parameters scored, with minimal difference in one landmark, the retrocardiac lung assessment. While further study is required to assess the clinical impact of the variance noted when evaluating lung parameters, the preservation or improvement of information in the remaining parameters following irreversible compression and soft copy interpretation is promising for the potential use of teleradiology in this population.

Data Interpretation, Statistical↗
PubMed1983

[Vertebral osteonecrosis. Apropos of 4 cases with slow spinal cord compression in 1 case].

The authors report on four cases of aseptic osteonecrosis of the vertebral body in adults (VON). Among these, one patient, in whom histological data were available, presented with a slow spinal cord compression syndrome (SSCCS). This complication is uncommon since only one other similar case has been reported so far (4). VON thus remains an underestimated etiology of SSCCS by non-tumoral compression fracture of the vertebral body. Diagnosis is based on the roentgenograms which evidence osteocondensation with "gaseous dissection" of the vertebral body, the latter being considered as pathognomonic of this disease. The etiopathogeny is still unknown. Treatment is purely symptomatic and the course has always been favorable.

Aged↗
PubMed1974

Inert gas narcosis, the high pressure neurological syndrome, and the critical volume hypothesis.

The hypothesis that general anesthesia or pressure-induced convulsions occur when a hydrophobic region is expanded or compressed, respectively, by critical amounts is consistent with recent data obtained with mice. Calculations show that anesthesia occurs at an expansion of 1.1 percent and convulsions at a compression of 0.85 percent, the latter site of action being more compressible.

Anesthesia, General↗
PubMed2001

Brain-stem compression in vertebrobasilar dolichoectasia. A multimodal electrophysiological study.

OBJECTIVE: To evaluate the effects of mechanical compression of the brain-stem in patients with vertebrobasilar dolichoectasia (VBD). METHODS: In the framework of a prospective, observational study that collected clinical and laboratory data in patients with VBD, we studied 20 patients with compression of the brain-stem due to ectatic, tortuous basilar or vertebral arteries. Patients with cerebral lesions other than small lacunae in the white matter of the cerebral hemispheres were excluded from the study. Patients underwent vestibular and auditory function testing, including brain-stem auditory evoked potentials (BAEPs), blink reflex (BR), somatosensory evoked potentials (SEPs), and motor evoked potentials (MEPs). RESULTS: Almost all of the patients complained of auditory or vestibular symptoms and none had symptoms or signs of impairment of long tracts or the facial and trigeminal nerves. The most consistent findings were BR abnormalities with prolongation of ipsilateral R1 latency in cases of compression of the pons (10/16) and prolongation of the R2 and R2c latencies with compression of the medulla oblongata (5/15). Subclinical impairment of corticospinal pathways was found in 13 out of 25 instances of compression, and this was more frequent with compression of the pons. Abnormal BAEPs or SEPs were less frequently encountered, and only in cases with compression of the pons. CONCLUSIONS: Neurovascular compression of the brain-stem, even with severe distortion, is seldom associated with overt clinical signs, whereas subclinical dysfunctions are relatively frequent. The central pathways of the BR and the corticospinal pathways are more susceptible to compression than acoustic and sensory pathways. BR, MEP and BAEP data provide a functional evaluation of the brain-stem and some cranial nerves, which is lacking in imaging studies. Functional investigations may be useful in the long-term management of these patients, since VBD may be progressive and surgical correction may be required at some stage.

Adult↗
PubMed1996

Osteochondroma of the upper cervical spine. A case report.

STUDY DESIGN: A report of a patient with osteochondroma of the upper cervical spine causing radiculopathy. OBJECTIVES: The surgical treatment of this patient involved the complete removal of tumor and compression of neural structures. SUMMARY OF BACKGROUND DATA: Osteochondromas affect mostly the long bones. Involvement of spine by solitary osteochondromas is rare condition. The present report represents a case of spinal osteochondroma causing neurologic symptoms. METHODS: Cervical osteochondromas, best evaluated with routine magnetic resonance imaging and noncontrast computed tomography scans, rarely contribute to cervical nerve root compression. RESULTS: The patient's symptoms gradually resolved after gross total tumor removal. CONCLUSIONS: Symptomatic spinal osteochondromas are rare occurrences in an individual surgeon's experience. Computed tomography or magnetic resonance imaging are the imaging procedures of choice. In the majority of patients with myelopathy or radiculopathy, surgery results in complete relief of symptoms as demonstrated in this case.

Adult↗
PubMed2005

A worldwide review of the uses of the uterine compression suture techniques as alternative to hysterectomy in the management of severe post-partum haemorrhage.

Postpartum haemorrhage (PPH) is a worldwide problem. The historical background dates back to William Smelley's in the seventeenth century in his famous treaty of the theory and practice of midwifery in 1752. Changes in clinical factors and surgical expertise compel the modern day midwife and obstetrician to be vigilant in identifying risk factors and apply appropriate solution early. The recent confidential enquiry into maternal death (why mothers die (2000-2002)) identifies areas of substandard care. The rising caesarean section rate adds to the rising incidence of PPH. The reduction in junior doctor's hours may limit the pool of experienced obstetric surgeons available to manage severe PPH competently. There can be major complications following radical surgery for PPH. These include loss of fertility, other morbidity and even maternal death. The invention of the B-Lynch surgical technique for the conservative management of PPH was first performed and reported by a consultant obstetrician and gynaecological surgeon in Milton Keynes NHS Trust publishing the first series of cases in BJOG 1997. This has made a significant impact on the conservative surgical management of massive PPH. There are now over 1300 successful applications of this technique worldwide (CB-Lynch personal communication). Other similar or modified techniques such as Cho's Square Suture and Haymen's modification of the B-Lynch Suture Technique have been introduced adding to more available methods of conservative surgery. The current list of publications of successful application of the B-Lynch compression technique is encouraging and more outcome data can be reported by a letter or e-mail to enquiries@cblynch.com. Obstetricians and midwives both in developed and underdeveloped countries should seek training and attend fire drills in PPH control to avoid maternal morbidity and death. There should be special concentration on effective conservative surgery such as uterine compression techniques to avoid major morbidity and loss of fertility.

Female↗

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