The Development and Application of a Cost-Effective Cervical Spine Phantom for Use in Fluoroscopically Guided Lateral C1-C2 Spinal Puncture Training.

BACKGROUND AND PURPOSE: Lateral C1-C2 spinal punctures are uncommon procedures performed by radiologists for access to CSF and contrast injection when a lumbar approach is contraindicated and an alternate method of access becomes necessary. There are limited opportunities to learn and practice the technique. We aimed to develop and assess the efficacy of a low-cost, reusable cervical spine phantom for training in fluoroscopically guided lateral C1-C2 spinal puncture. MATERIALS AND METHODS: The phantom was constructed with a cervical spine model, an outer tube representing the thecal sac, an inner balloon representing the spinal cord, and polyalginate to replicate soft tissue. The total cost of materials was approximately US $70. Workshops were led by neuroradiology faculty experienced in the procedure using the model under fluoroscopy. Survey questions were assessed on a 5-point Likert scale. Participants were given pre- and postsurveys assessing comfort, confidence, and knowledge of steps. RESULTS: Twenty-one trainees underwent training sessions. There was significant improvement in comfort level (Δ: 2.00, SD: 1.00, P value < .001); confidence (Δ: 1.52 points, SD: 0.87, P value < .001); and knowledge (Δ: 2.19, SD: 0.93, P value < .001). Eighty-one percent of participants found the model "very helpful" (5/5 on Likert scale), and all participants were "very likely" to recommend this workshop to others. CONCLUSIONS: This cervical phantom model is affordable and replicable and demonstrates training utility to prepare residents for performing lateral C1-C2 spinal puncture. This is a rare procedure, so the use of a phantom model before patient encounters is invaluable to resident education and training.

A dynamic micro-CT scanner based on a carbon nanotube field emission x-ray source.

Current commercial micro-CT scanners have the capability of imaging objects ex vivo with high spatial resolution, but performing in vivo micro-CT on free-breathing small animals is still challenging because their physiological motions are non-periodic and much faster than those of humans. In this paper, we present a prototype physiologically gated micro-computed tomography (micro-CT) scanner based on a carbon nanotube field emission micro-focus x-ray source. The novel x-ray source allows x-ray pulses and imaging sequences to be readily synchronized and gated to non-periodic physiological signals from small animals. The system performance is evaluated using phantoms and sacrificed and anesthetized mice. Prospective respiratory-gated micro-CT images of anesthetized free-breathing mice were collected using this scanner at 50 ms temporal resolution and 6.2 lp mm(-1) at 10% system MTF. The high spatial and temporal resolutions of the micro-CT scanner make it well suited for high-resolution imaging of free-breathing small animals.

Quantitative measurements of cerebral metabolic rate of oxygen utilization using MRI: a volunteer study.

Quantitative estimates of cerebral metabolic rate of oxygen utilization using magnetic resonance imaging can have profound implications for the understanding of brain metabolic activity as well as the investigation of cerebrovascular disease. In this study, five normal volunteers were studied. All images were acquired on a Siemens 1.5 T scanner (Siemens Medical Systems Inc, Erlangen, Germany). Cerebral blood flow (CBF) was obtained in vivo with a dynamic imaging approach and the acquired images were post-processed with the singular value decomposition method (SVD). In addition, a multi-echo gradient echo/spin echo sequence was employed to provide MR estimates of oxygen extraction fraction (MR_OEF) in vivo. Subsequently, an absolute measure of MR cerebral metabolic rate of oxygen utilization (MR_CMRO(2)) was obtained in all subjects by taking the product of CBF and MR_OEF. A mean MR_CMRO(2) of 28.94 +/- 3.26 ml/min/100 g and 12.57 +/- 3.11 ml/min/100 g was obtained for gray matter and white matter, respectively, suggesting that the gray matter utilizes more oxygen than white matter under normal physiological conditions. These results yield a gray matter to white matter CMRO(2) ratio of 2.37 +/- 0.37, which is comparable to the reported values in the literature. More studies are needed to further improve on the accuracy as well as shortening the required data acquisition time so that the proposed approaches can be utilized in a routine clinical setting.

Soluble electroluminescent poly(phenylene vinylene)s with balanced electron- and hole injections.

We report a new route for the design of efficient soluble electroluminescent PPV-based copolymers bearing electron-deficient oxadiazole (OXD) moieties on side chains. The introduction of OXD through a long alkylene spacer with PPV backbone provides a molecular dispersion of OXD in the film; both the side chain OXD and the main chain PPV do retain their own electron-transport and emissive properties, respectively. The use of phenylene vinylene derivatives with asymmetric and branched substituents and a long spacer provides solubility for ease of device fabrication as well as amorphous structure to allow a well-mixing of OXD groups with the main chains. By properly adjusting the OXD content through copolymerization, we can tailor the chemical structure of electroluminescent material to give a balance of hole- and electron injections for various metal cathodes, such that the quantum efficiency is significantly improved and the turn-on voltage is reduced for the devices with aluminum and calcium. For the device with calcium fabricated in open air, a maximum brightness of 15000 cd/m(2) at 15 V/100 nm and a maximum luminance efficiency of 2.27 cd/A can be obtained, respectively, about 30 times brighter and 9.4 times more efficient than those with the corresponding homopolymer, poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV). The use of physical blends to simulate the copolymers provides no significant improvement, since phase-separation structures appear, causing an inefficient utilization of OXD and sometimes voltage-dependent emission spectra. The present route permits a fabrication of single layer PLED with high brightness, high efficiency, and low turn-on voltage.

Contrast-enhanced B-mode US angiography in the assessment of experimental in vivo and in vitro atherosclerotic disease.

RATIONALE AND OBJECTIVES: This study was performed to (a) test the hypothesis that filling the arterial lumen with echoes at B-mode ultrasound (US) enables the assessment of wall and luminal abnormalities and (b) compare contrast material-enhanced B-mode US with color and power Doppler US angiography. MATERIALS AND METHODS: Atherosclerotic lesions were created in 14 rabbit aortas and imaged with color Doppler and B-mode US before and after the intravenous administration of 0.3 mL of AF0150, a US contrast agent. In addition, four replicas of diseased human carotid arteries were immersed in a tissue-mimicking phantom and imaged with B-mode and color and power Doppler US before and after the administration of 1 mL of AF0150 per liter of porcine blood. Radiopaque plastic casts of the rabbit aortas and contact radiographs of the plastic replicas served as standards. RESULTS: Although color and power Doppler US allowed immediate localization of the lumen, precise estimation of stenoses and reliable visualization of surface irregularities were not possible. After AF0150 administration, angiogram-like images of the lumen were created with B-mode US, allowing rapid assessment of the entire vessel lumen and wall. Consequently, luminal stenoses were more accurately measured than with unenhanced B-mode US (r2 = 0.94, P < .0001 vs r2 = 0.21, P = .25) or Doppler (r2 = 0.42, P < .03). In addition, plaques and ulcerations were visible only with contrast-enhanced B-mode US. CONCLUSION: Microbubbles fill the arterial lumen with echoes at B-mode US, creating an angiogram-like image. The ability to visualize the inner and outer surfaces of the vascular wall improved the evaluation of luminal and wall abnormalities.

Functional voiding disorders in women.

From July 1986 to Dec 1987, 78 women complaining of frequency, urgency, dysuria and suprapubic discomfort were evaluated at our clinic. Their ages ranged from 20 to 68 (mean age: 38.2). The patients who were noted to have evidence of pyuria, neurological or gynecological abnormalities were excluded from the study. Urodynamic examinations including uroflowmetry, cystometry (CMG), urethral pressure profiles (UPP) and electromyography (EMG) of the external urethral sphincter were performed. The results revealed low flow rates in 56 patients (71.8%), non-relaxation of the external sphincter during voiding in 55 patients (70.5%), unstable bladder in 6 patients (7.7%) and a high maximal urethral closure pressure (MUCP) (greater than 80 cmH2O) in 44 patients (56.4%). The average volume of the cystometric capacity (250 +/- 86 ml) was decreased. The association between the low flow rate, non-relaxation of the external sphincter and a high MUCP was statistically significant. Urethral hypersensitivity has been recognized as being the major cause of these symptoms.

Induction of epidermal and hepatic ornithine decarboxylase by a Prudhoe Bay crude oil.

Application of a Prudhoe Bay crude oil (PBCO) to the backs of mice caused a rapid induction of epidermal ornithine decarboxylase (ODC). A maximum induction of over 60-fold was seen at 6 hr after application of 50 microliters of PBCO. Concurrently, epidermal putrescine levels were elevated 4.7-fold over controls. Intraperitoneal administration of PBCO led to a 15-20-fold increase in hepatic ODC activity but to a 45% decrease in the renal enzyme activity. Maximum induction of ODC was seen at 12 hr following the administration of 4 ml/kg body wt of PBCO. Hepatic putrescine levels were elevated 34-fold over controls. Pretreatment of mice with the protein synthesis inhibitor cycloheximide abolished both epidermal and hepatic ODC induction.

Toxicity of petroleum crude oils and their effect on xenobiotic metabolizing enzyme activities in the chicken embryo in ovo.

Microliter quantities of a Prudhoe Bay crude oil (PBCO) applied to the shell of fertile chick eggs during various stages of development induced cytochrome P-450 levels and mixed-function oxidase activities within the liver of the embryo. PBCO (5 microliter) applied on Day 11 of incubation was found to maximally induce within 24 hr embryo hepatic cytochrome P-450 levels (fourfold), naphthalene hydroxylase (sixfold), benzo[a]pyrene 3-hydroxylase (14-fold), and 7-ethoxyresorufin O-deethylase (24-fold). Glutathione S-transferase was not induced. Crude oils are known to be highly toxic to avian embryos, especially during the early stages of development. The LD50 of PBCO and Hibernia crude oil applied to the egg shell on Day 8 of incubation was found to be 1.3 and 2.2 microliter, respectively. Mixed-function oxidase-dependent metabolism of crude oil components may be required for toxicity since administration of 20 micrograms of disulfiram in dioxane 1 hr prior to application of 1.3 microliter of PBCO reduced embryo mortality from 60 to 20%.

Biochemical and functional disturbances in red blood cells of herring gulls ingesting Prudhoe Bay crude oil.

Heinz body hemolytic anemia developed in Herring Gull (Larus argentatus) nestlings given oral doses of 10 ml of Prudhoe Bay crude oil per kilogram of body weight per day for 5 days. Associated disturbances in red blood cells were increased amounts of reduced glutathione (GSH), peroxidation of membrane lipids, an increase in membrane permeability, and a decrease in the oxygen-carrying capacity of cyanomethemoglobin-convertible hemoglobin. Among groups of gulls given different cumulative doses of oil over a 6-day period, significant covariance with dose and dependence on dose was demonstrated for packed cell volume, hemoglobin, and red cell GSH. Rapid defecation of oil by gulls indicated that the effective dose was substantially less than the administered dose. Pronounced damage to red cells occurred in some birds administered oil for only 2 days. These data imply that the toxic effects of ingested oil may contribute significantly to the morbidity and mortality of oil-contaminated birds.

Effects of ingestion of hibernia and Prudhoe Bay crude oils on hepatic and renal mixed function oxidase in nestling herring gulls (Larus argentatus).

Oral administration of Prudhoe Bay crude or Hibernia crude to nestling herring gulls increased the hepatic cytochrome P-450 content 4-fold. Concomitantly, there was an increase in various mixed-function oxidase and phase II enzyme activities. 7-Ethoxyresorufin O-deethylase was elevated 19-fold, benzo(a)pyrene 3-hydroxylase 6-fold, aniline hydroxylase 3-fold, and aminopyrine N-demethylase and uridine diphosphate glucuronyl transferase 2-fold. There was no change in reduced glutathione S-transferase activity. Renal mixed-function oxidase activities were also elevated. Herring gull livers contained very low levels of DT-diaphorase activity which was inducible 3- to 5-fold by oil administration.

Structural studies on the O-antigen of Aeromonas salmonicida.

Lipopolysaccharide from a strain of Aeromonas salmonicida salmonicida was isolated from cells by the aqueous phenol method in 2.3% yield (based on dry weight of bacteria). Hydrolysis of the lipopolysaccharide in 1% acetic acid afforded O-polysaccharide (19% by weight), core-oligosaccharide (12.2%) and lipid A (44.6%). Analysis indicated that 3-deoxy-D-manno-2-octulosonic acid was absent from the lipopolysaccharide and that no low-molecular-weight compounds were released by the mild hydrolysis. The O-polysaccharide had the monosaccharide composition of rhamnose, glucose and N-acetylmannosamine in molar ratio of 1.0:1.58:0.83. 75% of the N-acetylmannosamine residues were substituted at position 4 by O-acetyl groups. Hydrolysis of the methylated polysaccharide proved to be both difficult and dependent on the method of hydrolysis chosen, in all cases a partially methylated disaccharide of rhamnose and N-acetylmannosamine was identified in the hydrolysate. Methylation analysis, periodate oxidation and proton magnetic resonance analysis were used to confirm the structure of the repeating unit as: (formula; see text).

Chondroitinase-producing bacteria in natural habitats.

A search was undertaken for bacteria which degrade chondroitin sulfate in nature and to find bacteria with a usefully high rate of chondroitinase (ChSase) productivity. First, 253 ChSase-producing bacteria were obtained from aquatic and land environments in Japan by aerobic and anaerobic screening methods. Identification according to Bergey's Manual of Determinative Bacteriology or Bain and Shewan (1968) permitted assignment of the majority of the isolates to seven genera, Aeromonas, Vibrio, Flavobacterium, Beneckea, Proteus, Micrococcus, and Arthrobacter. Next, ChSase productivities of all the isolates were compared with those of two established ChSase-producing stock strains, Proteus vulgaris NCTC 4636 and Flavobacterium heparinum ATCC 13125. As a result, special attention was given to production by a strain of Aeromonas sp. of large quantities of extracellular ChSase-AC. None of the isolates from the current study displayed significant ChSase-ABC productivity. Finally, ChSase-AC was prepared from the culture fluid of the Aeromonas strain by fractional precipitation with ammonium sulfate, chromatography on phospho-cellulose and diethylaminoethyl-cellulose, and gel filtration on Sephadex G-200. It was concluded that the Aeromonas strain may represent a profitable source of the enzyme ChSase-AC.