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Biomedical subjects

V C Traynelis

Publications and source records attributed to V C Traynelis.

At least 37 records · Page 2Linked to original sources
PubMed1997

Increased height in patients with medulloblastomas.

OBJECTIVE: Medulloblastomas demonstrate histological features similar to neuroendocrine tumors. Expression of various receptors for growth factors and production of growth hormones have been identified to occur with medulloblastomas. We studied the preoperative height of patients with medulloblastomas. METHODS: We studied 85 patients (64 children and 21 adults) with medulloblastomas and 42 patients (27 children and 15 adults) with cerebellar astrocytomas who served as a control group. All of the patients had their height and weight documented on standardized growth charts. In addition, age, sex, symptoms, radiographic findings, treatment, and survival were examined. RESULTS: Preoperatively, 22.4% of the patients with medulloblastomas were above the 95% curve in height and 80.0% were above the 50% curve for height. Compared with patients with cerebellar astrocytomas, 7.1% were above the 95% curve for height and 54.8% were above the 50% curve for height. The distribution of patients along the weight curves for both tumor types demonstrated a slight prevalence for lower weights but was not significantly different from the national average. A significant number of patients presenting with medulloblastomas attained increased height, which was disproportionate to the weight loss generally observed with neoplasms. To our knowledge, the disproportionate number of patients with medulloblastomas and increased height has not been reported before. A similar deviation in height distribution from the normal population could not be identified in patients with cerebellar astrocytomas. CONCLUSION: This study suggests that medulloblastomas may be influenced by growth hormone production or may produce growth factors in vivo.

Adolescent↗
PubMed1997

Chymopapain-induced reduction of proinflammatory phospholipase A2 activity and amelioration of neuropathic behavioral changes in an in vivo model of acute sciatica.

The mechanism of action underlying chymopapain (Chymodiactin) chemonucleolysis remains obscure. Radiographic studies suggest that chymopapain does not alter disc fragment size acutely; nonetheless, patients often report symptom resolution within a few days, even hours, of treatment. The authors postulate that, in addition to its chemonucleolytic action, chymopapain may possess antiinflammatory properties. To test this hypothesis, the authors assessed the ability of chymopapain to modulate the activity of the proinflammatory enzyme phospholipase A2 (PLA2) and to ameliorate behavioral changes associated with inflammatory neuropathy in an in vivo model of sciatica. Thirty-nine male Fischer rats were randomly assigned to one of three treatment groups: 1) saline, 2) betamethasone, or 3) chymopapain. All of the rats underwent unilateral sciatic nerve ligation with loose chromic gut suture to induce inflammatory mononeuropathy. The animals were tested for thermal and mechanical hyperalgesia on Days 0 (preoperation), 7 (pretreatment), and 14 (prior to death). Three animals were killed on Day 0 to determine the baseline PLA2 activity within unmanipulated rat sciatic nerves. On Day 7, three animals from each group were killed to assess PLA2 activity prior to treatment. The remainder were given a single infusion of saline, betamethasone (0.3 mg/kg), or chymopapain (100 pKat U) around the inflamed nerve. On Day 14, the remaining animals were killed and their sciatic nerves were removed. The tissue was homogenized and the PLA2 activity was determined using [14C]arachidonate-labeled Escherichia coli phospholipid membrane as a substrate. Lipids were extracted and separated by thin-layer chromatography. All animals developed behavioral changes consistent with inflammatory mononeuropathy 24 to 72 hours postoperatively; these included gait disturbance, flexion deformity, and hyperalgesia of the involved hindlimb. The degree of mechanical and thermal hyperalgesia was comparable between groups at Day 7. By Day 14, the thermal hyperalgesia had resolved; the mechanical hyperalgesia was less evident in the betamethasone- and chymopapain-treated groups than in the saline-treated controls (p = 0.003; saline- vs. chymopapain-treated groups p = 0.004; saline- vs. betamethasone-treated groups p = 0.008). The mean PLA2 activity at baseline (Day 0) was 11.6 +/- 4.9 nmol phospholipid hydrolyzed per minute per milligram of protein. The PLA2 activity at Day 7 was 74.4 +/- 18.2 (ligated side) and 21.2 +/- 11.7 (nonligated side). At Day 14, PLA2 activity was reduced in the chymopapain- (47.8 +/- 12.3) and betamethasone- (39.7 +/- 9.5) treated groups compared with the saline control group (62.3 +/- 11.2), (saline- vs. chymopapain-treated groups p < 0.05; saline- vs. betamethasone-treated groups p < 0.01). The PLA2 activity in nonligated specimens was 18.6 +/- 10.1. These data indicate that chymopapain exhibits antiinflammatory properties in vivo, reducing PLA2 activity and ameliorating mechanical hyperalgesia in this model of inflammatory sciatic neuropathy.

Acute Disease↗
PubMed1997

Assessment of primary and salvage lateral mass screw insertion torque in a cadaveric model.

This study was performed to determine the insertion torques of three types of lateral mass screws and to explore their relationship to bone mineral density (BMD). The peak insertion torque of primary articular screws was measured, and the holes were then stripped by overtightening. Larger diameter "salvage" screws were placed in the stripped holes, and peak insertion torque was measured. Peak primary screw insertion torque and BMD were positively correlated (r = 0.48, p = 0.00001). The ratio of salvage to primary screw insertion torque varied significantly among the systems (p = 0.0003). The positive correlation between BMD and primary screw peak insertion torque confirms the importance of bone density for satisfactory screw purchase. The large variation in the ratio of salvage to primary screw insertion torque among systems may be due to differences in primary and salvage screw design.

Bone Density↗
PubMed1996

Cervical spine motion with direct laryngoscopy and orotracheal intubation. An in vivo cinefluoroscopic study of subjects without cervical abnormality.

BACKGROUND: Cervical spine kinetics during airway manipulation are poorly understood. This study was undertaken to quantify the extent and distribution of segmental cervical motion produced by direct laryngoscopy and orotracheal intubation in human subjects without cervical abnormality. METHODS: Ten patients without clinical or radiographic evidence of cervical spine abnormality underwent laryngoscopy using a #3 Macintosh blade while under general anesthesia and neuromuscular blockade. Cervical motion was recorded with continuous lateral fluoroscopy. The intubation sequence was divided into distinct stages and the corresponding fluoroscopic images were digitized. Segmental motion, occiput through C5, was calculated for each stage using the digitized data. RESULTS: During exposure and laryngoscope blade insertion, minimal displacement of the skull base and rostral cervical vertebral bodies was observed. Visualization of the larynx created superior rotation of the occiput and C1 in the sagittal plane, and mild inferior rotation of C3-C5. C2 maintained nearneutral posture. This pattern of displacement resulted in extension at each motion segment, with the most significant motion produced at the occipitoatlantal and atlantoaxial joints (mean = 6.8 degrees and 4.7 degrees, respectively). Intubation created slight additional superior rotation at the occiput and C1, without substantial alteration in the posture of C2-C5. After laryngoscope removal, position trended toward baseline at all levels, although exact neutral posture was not regained. CONCLUSIONS: This investigation quantifies the behavior of the normal cervical spine during direct laryngoscopy with a Macintosh blade. With this maneuver, the vast majority of cervical motion is produced at the occipitoatlantal and atlantoaxial joints. The subaxial cervical segments (C2-C5) are displaced only minimally. This study establishes a highly reliable and reproducible method for analyzing cervical motion in real time.

Adult↗
PubMed1996

Biomechanical evaluation of Caspar and Cervical Spine Locking Plate systems in a cadaveric model.

There exist two markedly different instrumentation systems for the anterior cervical spine: the Cervical Spine Locking Plate (CSLP) system, which uses unicortical screws with a locking hub mechanism for attachment, and the Caspar Trapezial Plate System, which is secured with unlocked bicortical screws. The biomechanical stability of these two systems was evaluated in a cadaveric model of complete C5-6 instability. The immediate stability was determined in six loading modalities: flexion, extension, right and left lateral bending, and right and left axial rotation. Biomechanical stability was reassessed following fatigue with 5000 cycles of flexion-extension, and finally, the spines were loaded in flexion until the instrumentation failed. The Caspar system stabilized significantly in flexion before (p < 0.05) but not after fatigue, and it stabilized significantly in extension before (p < 0.01) and after fatigue (p < 0.01). The CSLP system stabilized significantly in flexion before (p < 0.01) but not after fatigue, and it did not stabilize in extension before or after fatigue. The moment needed to produce failure in flexion did not differ substantially between the two plating systems. The discrepancy in the biomechanical stability of these two systems may be due to differences in bone screw fixation.

Adult↗
PubMed1995

Assessment of unicortical and bicortical fixation in a quasistatic cadaveric model. Role of bone mineral density and screw torque.

STUDY DESIGN: The stabilizing potential of the Caspar Trapezial Osteosynthetic Plate was studied using unicortical and bicortical screw placement in cadaveric cervical spines. OBJECTIVE: To determine if Caspar plates secured with unicortical screws provide the same degree of stability as those anchored with unlocked bicortical screws. SUMMARY OF BACKGROUND DATA: Previous work has demonstrated that bicortical cervical vertebral screws are superior to unicortical screws in terms of pullout strength and decreased wobble. However, these two methods of plate fixation have not been directly compared in a clinically relevant cadaveric model. METHODS: The immediate and post-fatigue stabilizing potential of Caspar plates secured with unicortical or bicortical screws was assessed using a model of complete segmental instability. RESULTS: Unicortical screw placement resulted in inadequate stabilization in half of the cervical specimens. CONCLUSIONS: Our results suggest that, for the Caspar screw, bicortical fixation provides greater flexion-extension stability.

Biomechanical Phenomena↗
PubMed1995

Perioperative management and surgical outcome of the acromegalic patient with sleep apnea.

Sleep apnea is a rare complicating factor of acromegaly associated with a high risk of perioperative airway compromise and unclear response to transsphenoidal resection of the underlying pituitary tumor. We reviewed four acromegalic patients with sleep apnea and documented postoperative objective and subjective improvement of their sleep disorders. The pathogenesis of this disorder and safe perioperative airway management are discussed.

Acromegaly↗
PubMed1995

Cytotoxicity of cis-parinaric acid in cultured malignant gliomas.

The cytotoxic effects of cis-parinaric acid, a plant-derived 18-carbon polyunsaturated fatty acid, were assessed in vitro on normal and neoplastic glia. After being incubated for 24 hours in the presence of 12 mumol/L cis-parinaric acid, 36B10 glioma cultures demonstrated nearly 90% toxicity (unpaired Student's t test, P < 0.001). Similar results were obtained after the exposure of C6 rat glioma cultures, A172 human glioma cultures, and U-937 human monocytic leukemia cultures to cis-parinaric acid. In contrast, fetal rat astrocytes incubated with 12 mumol/L cis-parinaric acid demonstrated no significant toxicity (3% reduction, P = 0.12); fetal rat astrocytes showed only 20% toxicity after exposure to 40 mumol/L cis-parinaric acid (P = 0.001). The cytotoxic effects of cis-parinaric acid were antagonized with the addition of equimolar concentrations of alpha-tocopherol. Enzyme immunoassay of treated 36B10 glioma supernatant fluid for 8-isoprostane (a known oxidative metabolite) demonstrated a 10-fold increase of 8-isoprostane over 24 hours (123.0 +/- 10.3 versus 10.0 +/- 0.7 pg/ml for control, P < 0.001). These studies indicate that cis-parinaric acid may be significantly cytotoxic to malignant glioma cells in concentrations that spare normal astrocytes and that the mechanism of cytotoxicity is related to an oxidative process. The selective cytotoxic effect of cis-parinaric acid we describe represents the first step in the development of new chemotherapeutic agents for gliomas; these new agents act by preferentially enhancing lipid peroxidation in neoplastic cells.

Animals↗
PubMed1995

Spinal epidural hematoma following coronary thrombolysis with tissue plasminogen activator. Report of two cases.

Two cases of spinal epidural hematoma following intravenous administration of recombinant tissue-type plasminogen activator are presented. Both patients received thrombolytic therapy for acute myocardial infarction; back pain and progressive neurological dysfunction ensued, secondary to spinal cord compression caused by epidural hematoma. Both individuals underwent emergency surgery for decompression and hematoma evacuation, resulting in improvement in neurological function. The current status of thrombolytic therapy is reviewed, with emphasis on complications of therapy that require neurosurgical intervention.

Aged↗
PubMed1995

Biomechanical analysis of bone mineral density, insertion technique, screw torque, and holding strength of anterior cervical plate screws.

The bone mineral density (BMD) of 99 cadaveric cervical vertebral bodies (C3-7) was determined using dual x-ray absorptiometry. The vertebral bodies were randomly assigned to receive either a unicortical (51 bodies) or bicortical (48 bodies) Caspar cervical plating screw. The initial insertion torque was measured using a digital electronic torque wrench, and the force required to withdraw the screw from the vertebral body was determined. The mean BMD for the total group of 99 was 0.787 +/- 0.154 g/cm2, the mean insertion torque was 0.367 +/- 0.243 newton-meters, and the mean pullout force was 210.4 +/- 158.1 newtons. A significant correlation was noted between BMD and torque (p < 0.0001, r = 0.42), BMD and pullout force (p < 0.0001, r = 0.54), and torque and pullout force (p < 0.0001, r = 0.88). Although the BMD of the unicortical and biocortical groups was equivalent (p = 0.92), the insertion torque and pullout force differed significantly (p = 0.02 and p = 0.008, respectively) for the unicortical and bicortical groups. A holding index for each screw and insertion technique was defined as the product of the BMD and insertion torque. The calculated holding index and resultant pullout force were significantly correlated for both techniques of screw insertion (r = 0.92), and a significant difference in holding index was observed with unicortical versus bicortical screw placement (p = 0.04). The determination of BMD and measurement of insertion torque to create a unique holding index provides an assessment of bone-screw interaction and holding strength of the screw, both of which impact on the resultant stability of cervical instrumentation. As the number of cervical plating systems increases, the determination of a holding index for various screws and insertion techniques may assist in the comparison of cervical instrumentation.

Absorptiometry, Photon↗
PubMed1994

Plasma osmolality and brain water content in a rat glioma model.

Little is known about how intravenous fluids influence peritumoral edema formation. This experiment was designed to determine, in a rat glioma model, whether changes in plasma osmolality alter water content, as assessed by specific gravity (SpGr), in normal and neoplastic cerebral tissue. Cells cultured from an ethylnitrosourea-induced rat glioma were stereotactically implanted into the right striatum of Fischer 344 rats. A tumor growth interval of 21 days was allowed. In a second experiment, rats underwent a 60-second cortical freeze injury followed by 24 hours' recovery. In both experiments, rats were assigned to one of three groups: hypotonic (100 ml/kg of 0.2 mol/L NaCl in H2O, intraperitoneally; resultant plasma osmolality approximately 268 mOsm/kg); isotonic (no treatment; plasma osmolality approximately 298 mOsm/kg); or hypertonic (10 ml/kg of 1.0 mol/L NaCl in H2O, intraperitoneally; plasma osmolality approximately 342 mOsm/kg). Thirty minutes after fluid injection, regional SpGr was determined using a kerosene-bromobenzene gradient. In subsets of rats, the tissue morphology and blood-brain barrier permeability of Evans blue dye were assessed. Tissue within the freeze lesion was stained by Evans blue dye with sharp demarcation. Evans blue dye did not stain gliomatous tissue, and central necrosis was not histologically evident. In isotonic rats, glioma SpGr was reduced (1.0411 +/- 0.0012 g/ml) relative to the contralateral striatum (1.0437 +/- 0.0008 g/ml; P < 0.001). Despite this, a strong linear relation was observed for SpGr and plasma osmolality in both neoplastic and normal tissue. Within the freeze lesion in isotonic rats, SpGr was severely reduced (1.0335 +/- 0.0008 g/ml; P < 0.0001) compared with contralateral frontal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Herniated thoracic disks: treatment and outcome.

The optimal surgical approach for thoracic disk herniation is controversial, and long-term follow-up is poorly documented. We retrospectively reviewed the records of 31 patients who underwent surgery for herniated thoracic disks at our institution during a 17-year period (1975-1992). Two patients had multiple disk herniations; 16 of 33 herniated disks occurred at or below the T10-11 level. There were three surgical approaches to diskectomy: laminectomy in four patients, transpedicular surgery in 12, and costotransversectomy in 15. Weakness resolved postsurgery in nine of 18 patients. One patient transiently deteriorated neurologically after a laminectomy, three had wound infections, and two required second operations for their herniated disks. Postsurgery half the patients with symptoms continued to have pain or weakness.

Adult↗
PubMed1993

Cerebral blood flow in a rat glioma model during halothane anesthesia.

Little is known about the influence of infiltrating gliomas on the responsivity of the cerebral circulation to anesthetic agents. Therefore we designed a study to address this issue. Male Fischer 344 rats were assigned to two tumor groups and one sham group. In the two tumor groups, glioma cells were stereotactically injected into the right striatum; animals in the sham group were injected with sterile culture medium only. Either 12 or 16 days after injection, the rats were anesthetized with 1 MAC halothane in 40% O2/balance N2. Local and remote regional cerebral blood flow was then determined using 14C-iodoantipyrine autoradiography. Physiologic values (PaCO2, PaO2, pHa, mean arterial pressure, and rectal temperature) were similar for both tumor and sham groups. Tumor volume was relatively small (cross-sectional diameter = 2-3 mm), and there was no evidence of midline shift in coronal tissue sections. Blood flow within the tumor was substantially reduced relative to adjacent structures (e.g., tumor = 88 +/- 10 ml/100 g/min; adjacent caudate = 161 +/- 23 ml/100 g/min). There were no significant differences between the tumor and sham groups for regional blood flow values in histologically normal tissue in either the injected or contralateral hemispheres. We conclude that this model of brain neoplasia shows no evidence of either local or remote changes in the cerebrovascular responsibility of normal tissue to volatile anesthesia.

Anesthesia, Inhalation↗
PubMed1993

Biomechanical comparison of anterior Caspar plate and three-level posterior fixation techniques in a human cadaveric model.

Traumatic cervical spine injuries have been successfully stabilized with plates applied to the anterior vertebral bodies. Previous biomechanical studies suggest, however, that these devices may not provide adequate stability if the posterior ligaments are disrupted. To study this problem, the authors simulated a C-5 teardrop fracture with posterior ligamentous instability in human cadaveric spines. This model was used to compare the immediate biomechanical stability of anterior cervical plating, from C-4 to C-6, to that provided by a posterior wiring construct over the same levels. Stability was tested in six modes of motion: flexion, extension, right and left lateral bending, and right and left axial rotation. The injured/plate-stabilized spines were more stable than the intact specimens in all modes of testing. The injured/posterior-wired specimens were more stable than the intact spines in axial rotation and flexion. They were not as stable as the intact specimens in the lateral bending or extension testing modes. The data were normalized with respect to the motion of the uninjured spine and compared using repeated measures of analysis of variance, the results of which indicate that anterior plating provides significantly more stability in extension and lateral bending than does posterior wiring. The plate was more stable than the posterior construct in flexion loading; however, the difference was not statistically significant. The two constructs provide similar stability in axial rotation. This study provides biomechanical support for the continued use of bicortical anterior plate fixation in the setting of traumatic cervical spine instability.

Biomechanical Phenomena↗
PubMed1993

Cervical spine injury in an air-bag-equipped vehicle.

We describe a patient who suffered an upper cervical spine fracture despite wearing a seat belt and deployment of an air bag system. All individuals treating trauma victims should be aware that a potentially life-threatening injury can occur despite proper use of optimal available restraints.

Accidents, Traffic↗