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Biomedical subjects

D Grob

Publications and source records attributed to D Grob.

At least 19 recordsLinked to original sources
PubMed1992

Translaminar screw fixation of the lumbar spine.

Lower lumbar spinal fusion was carried out in 72 patients by a technique which involved screw fixation of the facet joints. Stability was achieved and mobilisation was allowed immediately. Radiographs after operation showed bony fusion in 94.5%. Pain was diminished and 76% of the patients would undergo the same treatment again. There were no neurological complications. The technique is useful and safe for the fusion of short segments of the lumbar spine.

Adolescent↗
PubMed1992

Needlestick injury: blood, mononuclear cells, and acquired immunodeficiency syndrome.

INTRODUCTION: Because transmission of HIV to health care workers after needlestick injury has occurred mainly a result of deep insertion of large gauge needles, blood and viable mononuclear cells transferred after needlestick injury were measured. METHODS: Needles of 20 to 27 gauge were filled with HIV-1 seropositive blood and inserted through extracorporeal human skin or parafilm covering physiologic saline solution modified Drabkin's solution, or culture medium, or inserted directly into one of these fluids, to a depth of one third of the needle length (0.5 inch) for 1 second. Volume of blood transferred was measured by both modified Drabkin's method and by chromium 51 labeling of red blood cells. Transfer of viable mononuclear cells was measured by growth in culture medium containing autologous feeder cells. RESULTS: The volume of blood transferred from a needle passed through skin varied from 312 +/- 69 nl from a 20-gauge needle to 14 +/- 4 nl from a 27-gauge needle, as measured by modified Drabkin's technique, and from 404 +/- 80 nl to 12 +/- 3.1 nl, as measured by chromium 51 labeling of red blood cells. The volume of blood transferred from a needle passed through parafilm was twice that transferred through skin. The volume of blood transferred through skin was 40% that transferred directly into fluid not covered by any barrier; blood transferred through parafilm was 80% of that transferred directly. When needles containing blood were inserted into culture medium for 1 second in the absence of a barrier, at least one viable mononuclear cell was almost always transferred to fluid from all gauges of needle tested. Insertion of needles through skin prevented transfer of all viable mononuclear cells from only 3% to 5% of 20- to 23-gauge needles, and from 12% to 32% of 26- and 27-gauge needles. Parafilm was an even less effective barrier than skin. Insertion of needles through parafilm completely prevented transfer of viable mononuclear cells from no 20- to 23-gauge needles and from only 5% to 10% of 26- and 27-gauge needles. CONCLUSION: The volume of blood transferred after needle insertion through skin for 1 second varied with the gauge of the needle and was 30-fold higher from a 20-gauge than from a 27-gauge needle. Variable mononuclear cells were transmitted after insertion through skin from more than 95% of 20- to 23-gauge needles and from 68% to 88% of 26- and 27-gauge needles. Parafilm was less effective than skin in reducing transmission of blood and viable mononuclear cells.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Biomechanical evaluation of four different posterior atlantoaxial fixation techniques.

Four different techniques for posterior atlantoaxial fusion were tested in vitro: 1) wire fixation with one median graft (Gallie type); 2) wire fixation with two bilateral grafts (Brooks type); 3) transarticular screw fixation (Magerl); and, 4) two bilateral posterior clamps (Halifax). The experiment was designed to determine the immediate three-dimensional stability of the spinal construct. Ten fresh human cadaveric specimens were tested intact, injured, and instrumented with each of the fixation techniques. The injury consisted of a severe soft tissue injury model, in which the alar, transverse, and capsular ligaments were transected. The three-dimensional motions of C1 relative to C2 were measured as the specimens were subjected to loads of pure moments in flexion-extension, axial rotation, and lateral bending. Each fixation technique significantly decreased motion in all directions, as compared to the intact and injured spines. We found that the Gallie system generally allowed significantly more rotation in flexion, extension, axial rotation, and lateral bending than the other three fixation techniques. There was generally no significant difference between the amount of rotation with the other three fixation techniques. However, the Magerl technique tended to allow the least rotation. The anteroposterior translation of two points on C1 were about equal for all fixation techniques.

Atlanto-Axial Joint↗
PubMed1992

Antibodies against myofibrillar proteins in myasthenia gravis patients.

Antibodies against various myofibrillar proteins were measured by enzyme-linked immunosorbent assay (ELISA) in sera of thirty-one myasthenic patients. The antibody activity expressed as optical absorbance values was higher in 15 (48%) patients for myosin, 10 (32%) patients for tropomyosin, 9 (29%) patients for troponin, 7 (23%) patients for alpha-actinin, and 1 (3%) patient for actin as compared with 95% tolerance limits of eleven normal individuals. Twenty-five (81%) of the patients had one of these antibodies or more. Anti-myosin antibody titer was higher in male patients (0.447 +/- 0.196; mean +/- SD, p less than 0.05) than in female patients (0.316 +/- 0.107), and positively correlated with the age of onset of myasthenia gravis (r = 0.41, p less than 0.05). Anti-tropomyosin antibody titers had an inverse correlation with the age of onset (r = -0.46, p less than 0.01). No significant correlation was found between the antibody activities and other clinical conditions, including the severity and duration of disease, and treatments (systemic treatment with corticosteroids or previous thymectomy). Positive correlations were observed between anti-myosin antibody and anti-troponin antibody titers (r = 0.44, p less than 0.02), and between anti-actin antibody and anti-alpha-actin in antibody titers (r = 0.39, p less than 0.05), but no significant correlation between other pairs of antibodies against myofibrillar proteins was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of alar ligament transection on upper cervical spine rotation.

Fresh human cadaveric specimens of occiput (C0) to C3 were subjected to axial torque. The resulting physiological motions were studied in an unconstrained three-dimensional manner. Effects of sequential transections of the left and right alar ligaments on the relative motions of C0-C1 and C1-C2 were studied. After transection of the left alar ligament, ranges of motion--due to 1.5 Nm torque--increased at both the C0-C1 and C1-C2 joints. Increases were small, on average 1.9 degrees to each side and at each level. Increases due to subsequent cutting of the right alar ligament were, on average, only 0.5 degrees and statistically not significant. In general, neutral zones showed greater increases, e.g., 3.9 degrees to each side at the C1-C2 joint. Comparing right and left axial rotations, after transection of the left alar ligament, showed greater percentage increases for the right, as compared to the left, axial rotation, at both C0-C1 and C1-C2 joints. Functional loss of the alar ligaments indicates a potential for rotatory instability, which, however, must be determined in conjunction with other clinical findings, such as neurological dysfunction, pain, and deformity.

Adult↗
PubMed1991

Bone graft translation of four upper cervical spine fixation techniques in a cadaveric model.

The goal of spinal fixation is to promote bony fusion by restricting motion at the site of the bone graft. Therefore, in order to evaluate the efficiency of various cervical fixation techniques, we determined the translations at the posterior arch of C1 for four C1-C2 posterior techniques: Gallie, Brooks, Magerl, and Halifax. Our model was the cadaveric specimen, with extensive soft tissue injury: transection of the alar, transverse, and capsular ligaments. Under three-dimensional physiological loading, we recorded the motion of C1 relative to C2, and calculated the translations at the surface of the graft in three dimensions, 10 specimens being tested intact, injured, and instrumented with each of the techniques. We assumed that translational laxity or neutral zone was the critical motion parameter and evaluated it, quantified herein as the neutral zone, at seven points at the graft site. The three-dimensional neutral zone translations were analyzed by their axial and shear components. We found that there was no significant difference with the fixation techniques in the average axial translation (Brooks: 1.1 mm; Magerl: 1.3 mm; Gallie: 1.5 mm; and Halifax: 0.5 mm). In shear, the Magerl averaged 1 mm, which was significantly less than the Gallie (2.1 mm). The Brooks (1.6 mm) and Halifax (1 mm) were not different from each other, Magerl, or Gallie. We propose that evaluation by translational laxity (neutral zone) at the graft site is a noteworthy concept in biomechanical analysis.

Adult↗
PubMed1991

Circumferential fusion of the lumbar and lumbosacral spine.

Seventy-four patients with circumferential fusion of the lumbosacral spine have been assessed after a mean follow up of 49.8 months. For the ventral procedure, an anterior interbody fusion with tricortical iliac bone graft was performed. The additional dorsal fusion was according to various techniques with mainly transpedicular internal fixation. Forty-six patients underwent a one-stage operation while 28 underwent the ventral and dorsal procedure in different sittings. The results favour the technique of a combined anterior/posterior approach for fusion of the lumbosacral spine in patients with instability and deformity of all three columns, such as fractures and spondylolisthesis of more than 50%. Optimal stability with satisfactory reduction of the deformity may be achieved. The one-stage operation proved to be superior, with less complications and a shorter hospital stay.

Adolescent↗
PubMed1991

Effect of cocaine on responses of mouse phrenic nerve-diaphragm preparation.

Effects of 5 to 40 microM cocaine on the compound action potential (AP) and tension responses of the mouse phrenic nerve-diaphragm preparation were monitored following nerve and muscle stimulation at 37 degrees C. Cocaine caused concentration dependent reduction in amplitude of the nerve AP, muscle AP, and tension response to a single nerve stimulus, and greater reduction in amplitude of these responses to repetitive nerve stimuli at 100 Hz for 0.5 sec. Cocaine caused similar reduction in the muscle AP and tension responses to direct muscle stimulation in the presence or absence of curare, and markedly reduced the overshoot, total potential, and maximum rate of rise and fall of intracellularly recorded muscle AP, without affecting the resting potential, or the contracture responses evoked by caffeine. These results indicate that cocaine reduces skeletal muscle function by reducing the excitability of muscle and nerve membranes, without significantly affecting neuromuscular transmission, excitation-contraction coupling or contractility.

Action Potentials↗
PubMed1991

Characterization of in vivo-activated T cell clones from peripheral blood of multiple sclerosis patients.

In vivo-activated interleukin-2 responsive T cell clones were generated from peripheral blood (PBL) of multiple sclerosis patients (MS) and normal subjects (N) by limiting dilution analysis. The frequency with which interleukin-2 responsive cells were cloned from PBL was higher in MS than N. CD8 was the predominant phenotype expressed by both MS (85%) and N (89%) clones. Seven clones from four MS patients but none from five N subjects specifically proliferated against myelin basic protein. These studies demonstrate the existence of MBP-reactive T cells in PBL of MS patients.

Antigens, Surface↗
PubMed1991

Peripheral mechanisms of fatigue in muscles of normal and dystrophic mice.

We evaluated the contribution of different processes to fatigue of normal and dystrophic mouse muscles using an in vitro electromyography chamber. Fatigue was induced by repetitive nerve stimulation at 30 Hz for 0.5 s, every 2.5 s until tension decreased by about 50%. We monitored the compound nerve action potential (AP), compound muscle AP, and isometric tension responses to nerve stimulation, and compound muscle AP and tension responses to direct muscle stimulation. In normal mice, about 50% reduction in nerve-evoked tension occurred by 2.4 min in extensor digitorum longus (EDL), 4.8 min in diaphragm, and 9 min in soleus. Analysis of the responses revealed that the fatigue was caused by failure of more than one process in all muscles, and failure of nerve conduction did not contribute to fatigue in any muscle. Failure of neuromuscular transmission, muscle membrane excitation, and excitation-contraction (E-C) coupling and contractility accounted for 55, 45, and 0%, respectively, of the fatigue in EDL, for 21, 74, and 5% of the fatigue in diaphragm, and for 2, 54, and 44% of the fatigue in soleus. In dystrophic mice, while about 50% reduction in nerve-evoked tension occurred by 8.1 min in EDL and 5.6 min in diaphragm, only 29% reduction in tension occurred by 80 min in soleus. Failure of neuromuscular transmission, muscle membrane excitation, E-C coupling and contractility accounted for 22, 63 and 15% of the fatigue in EDL, for 21, 79, and 0% of the fatigue in diaphragm, and for 15, 59, and 26% of the fatigue in soleus. The proportion of slow-twitch oxidative fibers was more than normal in dystrophic EDL, but the same as normal in dystrophic diaphragm and soleus. The slower onset of fatigue was attributable to lesser failure of neuromuscular transmission in dystrophic EDL, and to lesser failure of E-C coupling and contractility in dystrophic soleus.

Animals↗
PubMed1991

Flexion, extension, and lateral bending of the upper cervical spine in response to alar ligament transections.

The purpose of this in vitro experimental study was to determine the role of alar ligaments in providing flexion, extension, and lateral bending stability to the upper cervical spine. Ten fresh human cadaver specimens occiput-C3 were studied in a complete unconstrained and three-dimensional manner, first intact and then after sequential cutting of the left and right alar ligaments. At the C0-C1 joint, there were increases in flexion motion with sequential cutting of the alar ligaments but none in extension. For the same joint, cutting of the left alar ligament resulted in a significant increase in neutral zone in right lateral bending but not in left lateral bending, whereas there were no significant increases in the ranges of motion. At the C1-C2 joint, there were significant increases both in flexion and extension due to cutting of the left alar ligament, but subsequent cutting of the right alar ligament resulted in a small increase for flexion only. At this joint, right lateral bending increased due to cutting of the left alar ligament, but the same was not true for the left lateral bending. Subsequent cutting of the right alar ligament resulted in significant increases for both the right and left lateral bending.

Adult↗
PubMed1991

Functional radiographic diagnosis of the lumbar spine. Flexion-extension and lateral bending.

Several attempts have been made to measure the segmental range of motion in the lumbar spine during flexion-extension with the purpose of gathering additional data for the diagnosis of instability. The previous studies were performed in vitro or in vivo during active motion. The aim of this study was to obtain normal values of passively performed segmental motions. Forty-one healthy adults were examined by means of functional radiographs during flexion-extension and lateral bending. A graphic construction method and a computer-assisted method were used to measure rotations. Comparing with recent in vivo studies, the values obtained for normal angles of rotation were predominately larger. This might be due to the passive examination used in the study. The graphic construction method and computer-assisted method techniques are equally reliable, but the computer-assisted method method yields other important kinematic data, such as translations. It is proposed that passive motion be applied during functional examination of patients with suspected instabilities. However, the large variation of rotational values between individuals in the normal population may limit the clinical usefulness of functional lumbar analysis using this parameter. Future studies should explore the clinical relevance of determining altered segmental mobility in low-back pain patients.

Adult↗
PubMed1991

Clinical validation of functional flexion-extension roentgenograms of the lumbar spine.

The purpose of this study was to determine the clinical validity of functional flexion-extension roentgenograms of the lumbar spine in a defined patient population. One hundred and one adults with low-back pain or functional disorders underwent passive functional flexion-extension examinations. Their roentgenograms were analyzed using a computer-assisted method to determine segmental motion parameters such as rotation and translation of the lumbar vertebrae. The patient population was broken down into five groups with similar pathologies or physical conditions, and their motion parameters compared to a normal population and to each other. It was found that all of the patient groups exhibited significantly hypomobile motion, spread equally among all levels, in comparison to the normal population, except for the group of high-performance athletes, who had significant hypermobility. The uniform spread of hypomobility limits the ability to distinguish with any confidence between the four pathologic groups by their motion. Thus, we believe that the analysis of the segmental motion of the lumbar spine using passive flexion-extension roentgenograms does not aid in differentiating the underlying pathologic condition of patients with low-back pain, and that no useful information can be derived form this procedure, especially in relation to the need for surgical intervention.

Adult↗
PubMed1991

Magnetic stimulation of motor cortex and motor roots for painless evaluation of central and proximal peripheral motor pathways. Normal values and clinical application in disorders of the lumbar spine.

Magnetic stimulation of the motor cortex, motor roots, and proximal nerve trunks was performed in 46 healthy adults and in 73 consecutive patients with disorders of the lumbar spine. In combination with neurography and F-wave recordings, the fractionated stimulation of the motor pathways allowed calculation of conduction times of the pyramidal tract fibers, of the motor roots (ie, caudal fibers), and of the motor fibers of the lumbosacral plexus. Normal values for motor conduction times to the quadriceps, anterior tibial, and extensor digitorum brevis muscles were established. Patients had clinical and radiologic diagnoses of spinal stenosis (n = 43) and nerve root compression syndromes (n = 30). Motor conduction times to lower limb muscles were significantly delayed (above mean normal value +/- 2 x SD) in 65% of the patients with spinal stenosis and 50% of the patients with nerve root compression syndromes. Conduction slowing could be localized within the motor root and caudal fiber segment of the motor pathways in 80% of the patients in whom F-waves could be recorded. This method can be used to verify, quantify, and locate lesions of the motor pathways in conditions such as compression of the spinal cord, the caudal fibers (spinal stenosis), or the motor root passing through the intervertebral canal.

Adult↗
PubMed1991

Transections of the C1-C2 joint capsular ligaments in the cadaveric spine.

The purpose of this study was to examine the mechanical function of the C1-C2 capsular ligaments. Physiologic torques of up to 1.5 Nm were applied to human fresh cadaveric specimens (C0-C1-C2-C3) in three dimensions, and the three-dimensional motion of C1 relative to C2 was recorded. Two groups of cadaveric specimens were used to study the effect of two different sequential ligamentous transections. In the first group (n = 4), the transection of the left capsular ligament was followed by transection of the right capsular ligament. In the second group (n = 10), the transection of the left capsular ligament was preceded by transection of the left and right alar and transverse ligaments. The greatest changes in motion occurred in axial rotation to the side opposite the transection. In the first group, left capsular transections resulted in a significant increase in axial rotation range of motion to the right of 1 degree. After the right capsular ligament was transected, there was a further significant increase of 1.8 degrees to the left and 1.0 degree to the right. Lateral bending to the left also increased significantly by 1.5 degrees after both ligaments were cut. In the second group, with the nonfunctional alar and transverse ligaments, transection of the left capsular ligament resulted in greater increases in range of motion: 3.3 degrees to the right and 1.3 degrees to the left. Lateral bending to the right also increased significantly by 4.2 degrees.

Cadaver↗
PubMed1991

Atlanto-axial fusion with transarticular screw fixation.

We reviewed 161 patients, from four centres in Switzerland, who had undergone posterior fusion of the upper cervical spine with transarticular screw fixation of the atlanto-axial joints. They were followed up for a mean 24.6 months. The vertebral artery and the medulla escaped injury and only 5.9% of the complications were directly related to the screws. The rate of pseudarthrosis was 0.6%.

Adolescent↗
PubMed1991

Posterior occipitocervical fusion. A preliminary report of a new technique.

A new technique for occipitocervical fusion is described. The fixation of the upper cervical spine with plates and screws avoids the possible disadvantages of the commonly used wiring technique. By the establishment of a rigid fixation between the occiput and upper cervical spine with a combination of plates and screws, especially with transarticular atlantoaxial screw fixation, reliable, multidirectional, and immediate stability is achieved. The clinical picture and analysis of 14 patients with a variety of pathologies of the upper cervical spine is presented. The satisfactory outcome and solid bony fusion in all 14 patients and the absence of severe complications encourages the continued use of this technique of occipitocervical fusion.

Arthritis, Rheumatoid↗