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Biomedical subjects

M Silberstein

Publications and source records attributed to M Silberstein.

At least 19 recordsLinked to original sources
PubMed2006

Online system for faster multipoint linkage analysis via parallel execution on thousands of personal computers.

Computation of LOD scores is a valuable tool for mapping disease-susceptibility genes in the study of Mendelian and complex diseases. However, computation of exact multipoint likelihoods of large inbred pedigrees with extensive missing data is often beyond the capabilities of a single computer. We present a distributed system called "SUPERLINK-ONLINE," for the computation of multipoint LOD scores of large inbred pedigrees. It achieves high performance via the efficient parallelization of the algorithms in SUPERLINK, a state-of-the-art serial program for these tasks, and through the use of the idle cycles of thousands of personal computers. The main algorithmic challenge has been to efficiently split a large task for distributed execution in a highly dynamic, nondedicated running environment. Notably, the system is available online, which allows computationally intensive analyses to be performed with no need for either the installation of software or the maintenance of a complicated distributed environment. As the system was being developed, it was extensively tested by collaborating medical centers worldwide on a variety of real data sets, some of which are presented in this article.

Algorithms↗
PubMed2006

A new look into kicking a football: an investigation of muscle activity using MRI.

The kicking action predominantly used in Australian Rules football is considered to be responsible for many lower limb injuries. The aim of this study was to describe a non-invasive method of identifying the thigh muscles involved in kicking an Australian Rules football, using MRI. Both upper thighs of 10 recreational footballers were examined using a 1.5-T General Electric MRI scanner before and immediately after carrying out a set kicking exercise protocol. The signal intensity (SI) changes in 14 individual muscles were investigated using a standardized region of interest to determine the levels of muscle activity. Significant SI changes were observed in several muscles of the kicking and stance legs among all participants. In the kicking leg, the greatest SI changes were observed in the adductor longus and tensor fascia latae muscles (49.38% (+/-8.95) and 45.47% (+/-7.91), respectively; P < 0.05), whereas in the stance leg, the muscles displaying the highest changes were the semitendinosus and tensor fascia latae muscles (46.48% (+/-9.97) and 33.68% (+/-8.36), respectively; P < 0.05). This study has shown that MRI can be useful for observing the activity of individual muscles in the upper thigh during the kicking motion. This non-invasive approach provides a detailed analysis of anatomy and emphasizes the muscles at high risk of injury.

Adult↗
PubMed1999

Spinal Schmorl's nodes: sagittal sectional imaging and pathological examination.

The presence, location and number of Schmorl's nodes was determined in the thoracolumbar spines of 70 motor vehicle accident victims using radiographic examination of a midline sagittal section and subsequent pathological examinations, including histology. In 28% of spines, a greater number of Schmorl's nodes were identified with radiography, while in 44%, pathological examination revealed a greater number of nodes. The visibility of Schmorl's nodes was enhanced by using a sagittal radiographic approach, and, in contrast to previous work, nodes below 0.5 cm2 were readily detected. The results of the present study offer an additional imaging technique for postmortem analysis of the spine, and support the use of sagittal MR imaging for the evaluation of this condition.

Accidents, Traffic↗
PubMed1998

The pathogenesis of Schmorl's nodes in relation to acute trauma. An autopsy study.

STUDY DESIGN: Seventy thoracolumbar spines from cadavers of individuals killed in motor vehicle accidents were examined pathologically and radiologically, particularly for the occurrence of acute Schmorl's nodes. OBJECTIVES: To document whether Schmorl's nodes occur acutely as a result of trauma. SUMMARY OF BACKGROUND DATA: Theories proposed to explain the pathogenesis of Schmorl's nodes include developmental, degenerative, traumatic, and disease influences. Few studies show a direct causal relation between a traumatic episode and acute Schmorl's node formation. METHODS: Thoracolumbar spines were removed at autopsy, underwent radiography in the anteroposterior and lateral planes, fixed, sagittally cut, and underwent radiography a second time. Pathologic and radiographic examinations were performed. RESULTS: Nine acute Schmorl's nodes were detected, most in association with other acute injuries to the spine. Most acute Schmorl's nodes were present in spines from individuals aged 11-30 years, with a male to female ratio of 9:1, and were localized to the T8-L1 region. Spines from motorcyclists showed the highest percentage of acute Schmorl's nodes. No acute Schmorl's nodes were detected radiologically. CONCLUSION: Schmorl's nodes do occur acutely as the result of a single traumatic episode, and are almost always associated with other acute spinal injury. The frequency and occurrence of acute Schmorl's nodes in motorcyclists suggest that axial loading is an important mechanism. Their predominance in the T8-L1 region suggests that this region is particularly susceptible to stress.

Acute Disease↗
PubMed1995

Fast magnetic resonance imaging in spinal trauma.

In a prospective comparison between fast magnetic resonance imaging (MRI) sequences and conventional spin-echo in a series of 20 patients, gradient-echo imaging was found to be inferior to spin-echo, especially in the visualization of spinal cord oedema, and the use of a rapid spin-echo sequence was limited by inferior visualization of haemorrhage. While the use of a combination of these two fast imaging techniques resulted in equivalent results to conventional spin-echo, the increased imaging time suggests that fast MRI cannot, as yet, replace conventional spin-echo techniques in acute spinal trauma.

Cerebrospinal Fluid↗
PubMed1994

Non-contiguous spinal injury: clinical and imaging features, and postulated mechanism.

In an attempt to identify possible mechanisms for remote or non-contiguous spinal injury, clinical records and magnetic resonance (MR) images were analysed in 71 consecutive patients admitted for management of acute cervicothoracic spinal trauma. Seven patients (10%) were identified with clinical or MR evidence of non-contiguous spinal injury, and either more than one neurological level, or a cord lesion remote from the imaging abnormality. Five of these had radiographic and MRI findings suggesting that the second lesion was due to cord stretching, following local tethering at the first level, including three patients with a small extramedullary haematoma at the site of the distant cord lesion. The other two patients had underlying multilevel degenerative spinal canal stenosis, explaining the second cord lesion. Non-contiguous spinal injury is an infrequent manifestation of acute spinal trauma, and, in contrast to most forms of cord injury associated with spinal trauma, which are due to cord compression, this entity may represent the sequel of cord stretching.

Adult↗
PubMed1993

The symptomatic lumbar disc in patients with low-back pain. Magnetic resonance imaging appearances in both a symptomatic and control population.

Magnetic resonance imaging of abnormal lumbar discs in 115 symptomatic patients (184 discs) and 63 symptom-free controls (78 discs) have been compared. All symptomatic patients were proven to have discogenic pain at discography. Discs were classified into patterns 1-6 reflecting the progressive changes of nuclear degeneration as previously described. In the symptomatic patient, the more degenerate the disc the more likely it was responsible for pain (P < 0.001), but there was no statistically significant difference in the distribution of abnormal signal patterns between the two groups studied. A small number of patients in both populations demonstrated high signal from disc protrusions but this also could not be used as a predictor of pain. No abnormal lumbar disc signal pattern could be identified that specifically indicated whether a disc would be painful. Magnetic resonance imaging is accurate in determining nuclear anatomy, but until more suitable techniques become available, discography is still the only method for symptomatic assessment in low-back pain.

Adult↗
PubMed1993

Implications of focal spinal cord lesions following trauma: evaluation with magnetic resonance imaging.

In a series of 15 patients who underwent early and follow up magnetic resonance imaging following spinal cord injury, those with focal spinal cord abnormalities such as cord contusion or haematoma had worse neurological outcomes, and most developed spinal cord cysts, showing as well-defined areas of CSF intensity within the cord on T1 weighted images. Patients with cord oedema initially, had better outcomes, with the development of residual areas of myelomalacia. These observations suggest that patients with focal initial spinal cord abnormalities may have an increased risk of developing posttraumatic spinal cord cysts, which may be associated with the development of delayed neurological deterioration.

Adolescent↗
PubMed1993

Evaluation of the diagnostic accuracy of MR imaging at 0.3 T, based on clinical follow up of 3262 examinations.

The results of 4504 0.3 T magnetic resonance (MR) examinations, of which 3262 had clinical follow up are described. The overall true positive rate of MR imaging was 72%, with a range of 69-100%. While the best results were obtained for evaluation of spinal cord syrinx and normal cerebral examinations, 31% of patients with cerebral demyelination were incorrectly diagnosed. The false positive rate was relatively low (3-5% in most cases), but a significant 17% of patients considered to have normal cerebral examinations were later shown to have pathology. While the true positive rate of magnetic resonance imaging was greater than that of the suspected clinical diagnosis (37% correct), the results of this assessment at 0.3 T are significantly poorer than those previously published at 1.5 T.

Diagnostic Errors↗
PubMed1993

Magnetic resonance imaging of central nervous system haemorrhage.

The variable magnetic resonance imaging appearances of central nervous system haemorrhage, both intra- and extra-axial, are described. These will vary with the type of image contrast (T1 or T2 weighting), the nature of the imaging sequence (spin-echo or gradient-echo) and the time from onset of haemorrhage. Magnetic resonance imaging is a useful technique for imaging haemorrhage in the central nervous system as it yields temporal information about haematoma development, and it is the only non-invasive means of imaging intraspinal haemorrhage. It is, however, limited in the imaging of haematomas within 24 h of onset and in subarachnoid haemorrhage where computed tomography is the investigation of choice.

Central Nervous System Diseases↗
PubMed1993

Fatal Clostridium septicum myonecrosis.

A 20 year old leukaemic patient with neutropaenia secondary to chemotherapy, who developed overwhelming sepsis, myonecrosis, vascular occlusion and necrotizing enterocolitis due to Clostridium septicum infection is described. Plain abdominal radiographs and a computed tomography scan of the abdomen and pelvis showed gas in the retroperitoneal soft tissues. Clostridium septicum septicaemia has a recognized association with malignancy and neutropaenia and has a high mortality if not diagnosed and treated early. Computed tomography scanning of the abdomen, pelvis and head is advised in any patient with a positive C. septicum blood culture.

Acute Disease↗
PubMed1993

Thymic hyperplasia in adults following chemotherapy for malignancy.

BACKGROUND: The accuracy of the assessment of patients with malignant disease and of their response to chemotherapy has been significantly improved with the routine availability of computerized tomography (CT) scanning. CT abnormalities, however, may be non-specific, especially after chemotherapy. Rebound enlargement of the thymus gland after chemotherapy induced atrophy is one cause of an abnormal thoracic CT scan on re-staging. AIMS: This phenomenon has previously been reported mainly in relation to the treatment of lymphoma and germ cell cancers. This paper highlights the occurrence of thymic hyperplasia after chemotherapy in these and other tumour types. METHODS: We discuss five cases including three patients with malignancies other than lymphoma in whom thymus enlargement occurred during or after intensive chemotherapy. RESULTS: Clear identification of the nature of CT abnormalities after chemotherapy, particularly in the mediastinum, is required prior to embarking on further anti-cancer treatments.

Adult↗