Small particle polyvinyl alcohol embolization of cranial lesions with minimal arteriolar-capillary barriers

Polyvinyl alcohol foam, prepared as small particles measuring 70-150 micron when injected in intracerebral arteries of the rat, adhere to the vascular endothelium, allowing the particles to be captured without necessarily wedging intraluminally. Based on this observation, small particle microembolization was performed in a series of patients who had hypervascular cranial lesions, whose matrices angiographically appeared to have at best minimal arteriolar-capillary barriers. Each case was associated with intracranial dural sinus or cerebral venous drainage. In addition, several lesions had either venous ectasia or venous aneurysms. Symptomatic improvement occurred in all cases without apparent neurologic or pulmonary complications. These examples demonstrate the ability of very small polyvinyl alcohol foam particles to remain within the interstices of vascular lesions that display evidence of only minimal arteriolar-capillary barriers.     

Reconnection of severed nerve axons with polyethylene glycol

Severed medial giant axons in crayfish can be rejoined in vitro with polyethylene glycol (PEG) to produce axoplasmic continuity and through transmission of action potentials. Severed axon-like processes of a mammalian neuroblastoma/glioma cell line seem to be rejoined to the cell body using PEG in tissue culture. Our data suggest that PEG might be used to rejoin severed axons in vivo in various organisms.     

The influence of carrier on 99mTc radiopharmaceuticals.

High specific activity 99mTc-labelled radiopharmaceuticals are required in order to avoid saturating receptor sites and to minimise pharmacologic or toxic effects. The specific activity of 99mTc-pertechnetate is maximised by use shortly after elution from a generator which had been eluted at frequent intervals. Effective specific activity can be maximised by a variety of means. Often is it possible to label a very small amount of precursor with a large amount of 99mTc and use the product without further purification; this is limited by the potency of the ligand and the efficiency of labelling, which in turn is affected by the choice of chelator. A variety of purification techniques have been used, ranging from solvent extraction, solid-phase extraction cartridges, and size-exclusion columns to high-pressure liquid chromatography. Excess unchelated thiol-containing ligands (e.g. N2S2, N3S) can be removed by a thiol-trapping resin. Finally, solid-phase synthesis, in which the precursor is immobilised on a solid support (resin or gold) and only released into solution during chelation of 99mTc, is a promising method. High specific activity will become increasingly important with the next generation of 99mTc radiopharmaceuticals.     

Cerebral perfusion imaging with technetium-99m HMPAO following cerebral trauma. Initial experience

Thirteen patients with cerebral trauma were studied for cerebral perfusion by the use of Tc-99m HMPAO scanning. CT imaging was performed on nine patients. Because of their clinical condition, four patients were scanned only in the planar mode to help establish the diagnosis of brain death. Other indications for study included gunshot wound and blunt or sharp object trauma with or without skull fracture. In all cases, HMPAO scans showed defects with a quality equivalent to or greater than that demonstrated by CT. Our initial results suggest that HMPAO may predict the degree of permanent damage and which patients may develop post-traumatic headache. A diagnosis of brain death can be established without the withdrawal of medical therapy.     

Mitochondrial DNA analysis of hybridization between sympatric white-tailed deer and mule deer in west Texas.

Sympatric populations of white-tailed deer and mule deer (Odocoileus virginianus and Odocoileus hemionus, respectively) on a west Texas ranch share a common mitochondrial DNA restriction map genotype. Phylogenetic analysis indicates that this genotype is more characteristic of O. virginianus than of O. hemionus. The genotype of west Texas deer differs from that of O. virginianus from South Carolina by five mutational events (1.3% sequence divergence), whereas it differs from that of O. hemionus from California by 17 events (5.5% divergence). We suggest that interspecies hybridization has occurred, primarily between mule deer bucks and white-tailed deer does, with preferential absorption of hybrid offspring into the mule deer gene pool. Introgressive hybridization may be involved in ongoing displacement of mule deer by white-tailed deer in west Texas.     

Development of validated disease activity and damage indices for the juvenile idiopathic inflammatory myopathies. II. The Childhood Myositis Assessment Scale (CMAS): a quantitative tool for the evaluation of muscle function. The Juvenile Dermatomyositis Disease Activity Collaborative Study Group.

OBJECTIVE: To develop, validate, and determine the measurement characteristics of a quantitative tool for assessing the severity of muscle involvement in children with idiopathic inflammatory myopathies. METHODS: The Childhood Myositis Assessment Scale (CMAS) was developed from 2 existing observational functional assessment tools to assess muscle function in the areas of strength and endurance across a wide range of ability and ages. The 14 ordinal items included were chosen to assess primarily axial and proximal muscle groups and are ranked with standard performance and scoring methods. Following the development of the CMAS, a training video and written instructions were developed and reviewed by the physicians participating in this study. Subsequently, utilizing a randomized block design, 12 physicians independently scored 10 children (9 with dermatomyositis, 1 with polymyositis; ages 4-15 years) twice in one day (morning and afternoon) on the CMAS. A pediatric physical therapist performed quantitative manual muscle strength testing (MMT) twice on each child (morning and afternoon), including the neck, trunk, and proximal and distal extremity muscle groups. RESULTS: The CMAS has a potential range of 0-51, with higher scores indicating greater muscle strength and endurance. The observed mean for the 10 patients was 36.4 (median 44, SD 14.1, observed range 5-51). The total score for the CMAS correlated with the physician's global assessment (by visual analog scale) of disease activity, the MMT score, serum creatine kinase level, and the Juvenile Arthritis Functional Assessment Report score. The score on the CMAS was not correlated with patient age. Interrater reliability (Kendall's coefficient of concordance) ranged from 0.77 to 1.0 for individual items (all P < 0.001), and overall, it was 0.95 (P < 0.001). Intrarater reliability for the individual physicians was measured by correlation of the CMAS scores for each patient on 2 separate evaluations and ranged from 0.97 to 0.99, with an overall correlation for all physicians of 0.98 (all P < 0.001). CONCLUSION: The CMAS demonstrated an acceptable range of observed scores, excellent convergent validity, and excellent inter- and intrarater reliability. The CMAS is validated to quantitatively assess muscle function in the areas of strength and endurance in children with idiopathic inflammatory myopathies. It can be used in routine clinical care as well as therapeutic trials.     

Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room

Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR.It is critical to commence imaging as quickly as possible after exercise to capture exercise-induced cardiac wall motion abnormalities. We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table. We optimized the treadmill exercise CMR protocol in 20 healthy volunteers and successfully imaged cardiac function and myocardial perfusion at peak stress, followed by viability imaging at rest. Imaging commenced an average of 30 seconds after maximal exercise. Real-time cine of seven slices with no breath-hold and no ECG-gating was completed within 45 seconds of exercise, immediately followed by stress perfusion imaging of three short-axis slices which showed an average time to peak enhancement within 57 seconds of exercise. We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress. This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.     

Creutzfeldt--Jakob Disease in Recipients of Human Growth Hormone in the United Kingdom: A Clinical and Radiographic Study

In the past 3 years there have been five further cases, in additionto one case reported in 1985, of Creutzfeldt-Jakob disease inrecipients of human growth hormone in the United Kingdom. Theclinical findings of two of these cases are described, demonstratinga typical presentation with a predominantly cerebellar syndromeat onset which is not commonly a presenting feature of sporadicCreutzfeldt-Jakob disease. In one case a ^99mTc hexamethylpropylenaminesingle photon emission tomographic scan showed marked impairmentof tracer uptake in the basal ganglia and cerebral cortex ata time when the clinical picture was predominantly cerebellar.This technique may be useful in early diagnosis. In the othercase post mortem examination of the brain showed prominent amyloiddeposition in the cerebellum, which has not been described previouslyin pituitary-hormone related Creutzfeldt-Jakob disease. Thepreviously published cases of growth hormone-related Creutzfeldt-Jakobdisease are reviewed and reasons for the particular clinicalpattern seen are discussed.