Biomedical subjects

D Grob

Publications and source records attributed to D Grob.

At least 73 records · Page 4Linked to original sources

PubMed1993

Effect of cocaine on leakage of creatine kinase from isolated fast and slow muscles of rat.

Since patients with cocaine overdose were reported to develop rhabdomyolysis involving skeletal muscle damage leading to elevated levels of serum creatine kinase (CK), we determined whether cocaine can directly act on isolated rat skeletal muscles and increase the leakage of CK. In the fast-twitch muscle such as the extensor digitorum longus (EDL), following exposure to normal physiological solution for 1, 2, 3, and 4 hr, the mean leakage of CK was 0.6, 0.7, 0.9, and 1.2 units/mg of muscle respectively. On exposure of EDL to 0.1, 0.5, and 1.0 mM cocaine, there was no significant change in CK leakage. In the slow-twitch muscle such as the soleus, following exposure to normal physiological solution for 1, 2, 3, and 4 hr, the mean leakage of CK was 1.5, 2.2, 2.7, and 3.1 units/mg, which was significantly greater (P < 0.001) than in EDL at each time interval. On exposure of soleus to 0.1 mM cocaine, the CK leakage did not increase significantly, but on exposure to 0.5 mM cocaine, it significantly increased to 2.4, 3.4, 4.4, and 5.7 units/mg, and on exposure to 1.0 mM cocaine, it further increased to 2.7, 4.9, 6.5, and 7.6 units/mg. The CK activity of fresh muscle homogenate was 115.5 units/mg in EDL and 51.9 units/mg in soleus. These results indicate that cocaine can directly act on skeletal muscle and increase the leakage of CK especially from slow-twitch muscle like soleus, but not from fast-twitch muscle like EDL.

Animals↗

PubMed1993

Clinical validation of functional flexion/extension radiographs of the cervical spine.

The aim of this study was to determine the clinical validity of functional flexion/extension radiographs of the cervical spine in a defined patient population. Sixty-four adults with functional disorders of the cervical spine underwent passive flexion/extension radiographic examinations. The radiographs were analyzed using a computer assisted method to calculate segmental motion parameters, such as rotations, translations, and centers of rotation. The patients were separated into three groups based on their specific functional disorders, and their motion parameters were compared with those of a healthy population. The three groups consisted of patients with degenerative changes, those with radicular syndrome, and those with whiplash trauma. Most of the patients displayed trends toward hypomobile segmental motion. This trend is displayed more substantially in the groups with degeneration and radicular syndrome. Hypomobility in segmental rotation was significant at C6-C7 for the degenerative and radicular groups. The trauma group showed trends toward hypermobility in the upper and middle cervical levels, and the locations of the centers of rotation were shifted in the anterior direction when compared with those of the healthy population.

Adult↗

PubMed1993

[External fixator of the cervical spine--a new diagnostic tool].

Soft tissue injuries of the neck may cause severe long-standing pain. The clinical findings are sparse and the identification of the painful segments with conventional diagnostic tools is often impossible. Temporary segmental external fixation for a soft tissue injury of the cervical spine was performed as a diagnostic procedure in 24 patients. The instrumentation was applied according to the established techniques of the insertion of facet screws in the cervical spine. The segments to be instrumented were evaluated by clinical and radiological findings, such as local pain and increased mobility in the functional X-rays. However, none of these findings were convincing enough to proceed directly to fusion for pain relief. Evaluation of external fixation consisted of alternatively fixing different instrumented segments and having the patients rate their pain on a visual analogue pain scale. External fixation of the suspected segments resulted in marked pain relief, which was recorded subjectively by the visual analogue pain scale in 68% of the patients. The pain relief (8.2 points preoperatively--2.6 points postoperatively on average) could be permanently established by successful fusion of these segments in 17 patients. Four of the patients indicated no relief of pain at the follow-up (12.9 months postoperatively). No fusion was performed in 3 patients in whom the diagnostic procedure with external fixation allowed no conclusion about the painful segment. As it is an invasive procedure, external fixation of the cervical spine should be reserved for cases, in which conventional methods have failed to established a clear diagnosis of segmental instability and conservative therapy could not relieve the symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Presence of cross-reactive antibodies to HTLV-1 and absence of antigens in patients with multiple sclerosis.

Antibodies to HTLV-1, as determined by ELISA, were highly elevated in the serum samples of four out of four (100%) patients with TSP, moderately elevated in four out of four (100%) HTLV-1 carriers, slightly elevated in 12 out of 34 (35%) patients with MS, and absent from the serum samples of 34 normal subjects. Western blot analysis showed that the antibodies to HTLV-1 antigens in MS serum were heterogeneous. Cultivation of peripheral blood lymphocytes (PBLs) from patients with MS or normal subjects did not generate HTLV-1 core p19 antigen in the supernatant of culture medium, whereas cultivation of PBLs from patients with TSP and carriers of HTLV-1 generated core p19 antigen after 3 days for up to 28 days of cultivation. HTLV-1 antigens were also expressed on the surface of PBLs in three out of four patients with TSP and in two out of four HTLV-1 carriers on days 14 and 28 of cultivation, as measured by indirect immunofluorescence or alkaline phosphatase staining, but were not found in PBLs of any of 34 patients with MS or 34 normal subjects. The data indicate that although cross-reacting antibodies appear in the serum of some patients with MS, not enough evidence exists to suggest that HTLV-1 antigen is being produced in MS or that HTLV-1 plays a role in the pathogenesis of this disease.

Adult↗

PubMed1993

[Histological changes in the ligamentum flavum in patients with spinal stenosis].

In 21 patients with spinal stenosis the ligamentum flavum was removed, histologically processed and the calcification was measured with an image analyzing computer. Nearly all the ligaments were calcified: on average 0.17%, with a maximum of 3.8%. There was a significant correlation between age and calcification. We compared these findings with those of a group of "normals". There we only found minimal calcification in 3 of 20 segments (0.025%, 0.049%, 0.22%). As these people were on average 85 years of age, this can be looked upon as normal degenerative changes. This illustrates the important role of calcification of the ligamentum flavum for spinal stenosis.

Aged↗

PubMed1993

[Significance of simultaneous fusion and surgical decompression in lumbar spinal stenosis].

In a prospective study 45 patients with clinically relevant spinal stenosis of the lumbar spine were randomized in three groups. Group 1 underwent isolated decompression without fusion, group 2 had decompression and selected fusion, and group 3 underwent fusion of all decompressed segments. Patients with previous surgery of the lumbar spine or obvious instability, such as spondylolisthesis, were excluded from the study. The results were dominated by the relevant clinical improvement in the symptoms of spinal stenosis in all three groups. There were no statistical significant differences in the clinical results between the patients with and without fusion. We conclude that in the absence of obvious segmental instability, no fusion is required for decompressive surgery in degenerative lumbar spinal stenosis.

Aged↗

PubMed1993

[Lumbar spinal stenosis in systemic diseases and in hereditary syndromes].

In the general category of congenital spinal stenosis, there is a group of patients with particular features: patients suffering from a hereditary or systemic disease with congenital narrowing of the spinal canal. Evaluation of their neurological symptoms is influenced by the peculiarities of the underlying disease. The tendency toward paralysis and paraplegia is much higher in those patients. Attention must especially be given to technical details when operating on achondroplastic dwarfs. Early, most extensive surgery is recommended. We report our experience between 1987 and 1992 with operations on 6 cases of stenosis of the lumbar canal with hereditary or systemic disease.

Achondroplasia↗

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↗