Biomedical subjects
Publications and source records attributed to G M Miller.
A case of adenomatoid odontogenic tumor in which trauma was apparently a significant causative factor is presented. Consultation with an oral pathologist prevented unnecessary radical surgery.
Sonicated lipid micelles, formed from phospholipids isolated from yolks of fresh hen eggs, were used as a model membrane system for studying the effects of several surfactants on membrane properties. The interactions of the surfactants with the model system were followed through the fluorescence of the hydrophobic probe l-anilino-8-naphthalenesulfonate. The surfactants investigated were polyoxyethylene sorbitan monolaurate (Tween 20), polyoxyethylene thioether (Sterox SK), mono-calcium salt of polymerized aryl alkyl sulfonic acids (Daxad 21), and alkylbenzyl quaternary ammonium halide (AHCO DD 50). All surfactants enhanced fluorescence of the membrane-bound probe, and the degree of this enhancement correlated with the previously established phytotoxicity of these substances. The results indicate that surfactants can produce distinct changes in artificial phospholipid membranes and suggest that this lipid interaction may account for altered membrane permeability characteristics in surfactant-treated plants. The effects are observable for surfactant concentrations as low as 0.0001% (w/v), representing an approximate 10-fold increase in sensitivity for detecting surfactant effects compared with previous results on permeability changes in isolated plant cells.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being "perpendicular to the skin in every plane" (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block. METHODS: Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6-C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient. RESULTS: The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 +/- 6.1 degrees (range, 50-78 degrees). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6-C7 level. CONCLUSIONS: These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block.
A study was undertaken comparing neurological magnetic resonance imaging at high (1.5 T) and mid (0.5 T) field strengths. Twenty-eight patients (20 head and 8 spine) from our routine case load volunteered to undergo two consecutive and identical MR studies on the two systems. The two MR systems were built by the same manufacturer and were equipped with essentially identical hardware and software. Individual patient studies were performed consecutively in adjacent MR suites, and pulse sequence parameters were replicated exactly at the two field strengths. One exception to this rule was that the second echo of the long TR sequence in the head was acquired with a narrow receiver bandwidth on the 0.5 T system. The resulting axial double echo long repetition time (TR) and sagittal short TR head images and sagittal short and double echo long TR spine images were graded by two blinded observers (senior staff neuroradiologists) on two levels. First, the images were graded for image quality, i.e., conspicuousness of artifacts and clarity in depiction of normal and pathologic anatomy. Second, diagnostic accuracy of MR was assessed relative to the clinical-pathologic diagnosis in each case. The image quality of the 1.5 T system was rated superior in both the head and spine for most specific items assessed. This observer preference for 1.5 T images did not, however, translate into greater diagnostic accuracy for the 1.5 T system in the head. Although the 1.5 T system did have a slight advantage in diagnostic accuracy in the spine, a significant difference was not found.
OBJECTIVE: To determine the MR appearance of spinal cord multiple sclerosis (MS) plaques in patients presenting with myelopathy by using a high-field (1.5 T) imager. MATERIALS AND METHODS: We studied 119 patients who underwent high-field (1.5 T) MR studies of the spinal cord for evaluation of myelopathy. All 119 patients were thought to have possible findings of spinal cord MS at the time of the MRI interpretation. RESULTS: Sixty-four plaques were studied in 47 patients with clinically definite MS and adequate quality MRI. Of these patients 68% had a single spinal cord plaque, 19% had two plaques, and 13% had three or more plaques. Sixty-two percent of the plaques occurred in the cervical spinal cord and most frequently involved the posterior (41%) and lateral (25%) aspects of the spinal cord. None of the 64 lesions involved the entire thickness of the spinal cord. The lesion length varied from 2 to 60 mm, with 84% of the lesions < 15 mm in length. The spinal cord diameter was unchanged in 84% of plaques, enlarged at the level of the lesion in 14%, and atrophic in 2%. Just over half (55%) of the plaques enhanced with intravenously administered gadolinium. Of the patients who received synchronous head and spinal cord examinations on the same day, 24% had normal findings on the MR study of the head. Follow-up spinal cord studies were available in nine patients. New lesions developed in two patients, while previously described lesions resolved. In three patients only new lesions developed. In four patients no change occurred in the existing number of cord plaques. CONCLUSION: Spinal cord demyelinating plaques present as well-circumscribed foci of increased T2 signal that asymmetrically involve the spinal cord parenchyma. Knowledge of their usual appearance may prevent unnecessary biopsy. An MR examination of the head may confirm the imaging suggestion of spinal cord demyelinating disease, because up to 76% of patients have abnormal intracranial findings. In the remaining 24% of cases in which the clinical diagnosis is not certain and MR findings in the head are negative, a follow-up spinal cord study is recommended, because these lesions evolve and change over time.
The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.
PURPOSE: To examine the clinical and radiographic findings in a large group of patients having or suspected of having a spinal dural arteriovenous fistula. METHODS: An analysis of 240 spinal angiograms in 132 patients revealed 97 vascular malformations that included 66 spinal dural arteriovenous fistulas. Sixteen patients had 1 or more normal spinal angiograms that were performed for suspected spinal dural arteriovenous fistulas on other imaging studies. The imaging and clinical data were reviewed in all patients who had or were suspected of having a spinal dural arteriovenous fistula and who had a spinal MR (n = 44) and a myelogram (n = 37). RESULTS: Spinal dural arteriovenous fistulas were more common in males (3.4:1) with an average age of 62 years (range, 37 to 81 years). The average time from onset of symptoms to diagnosis was 27 months. Clinical findings included weakness (55%), a progressive clinical course (100%), and a myelopathy on exam (84%). The nidus of the fistula was located between T-6 and T-12 in 61%, in the sacrum in 9%, and intracranially in 8%. In the spinal dural arteriovenous fistula group, vessels were seen on supine myelography in all patients. MR findings in this group included increased T2 signal in the cord (100%), gadolinium enhancement (88%), mass effect (45%), and flow voids (T1, 35%; T2, 45%). The patients in the negative spinal angiogram group were younger (average age, 51 years), had symptoms longer (average time from symptom onset to spinal angiogram, 59 months), and presented with numbness or pain (76%). When compared with the patients with spinal dural arteriovenous fistula, acute or stable deficits were more common (31%), and myelopathy on exam was less common (56%). Although the angiogram-negative patients commonly had vessels on the myelogram (92%), abnormal T2 signal in the cord was unusual (17%). CONCLUSIONS: In the appropriate clinical setting, high T2 signal of the spinal cord is the most sensitive imaging finding in spinal dural arteriovenous fistula. The presence of mass effect and enhancement should not discourage this diagnosis. The likelihood of finding a spinal dural arteriovenous fistula in a patient without T2 signal on MR is low.