Elemental composition and water content of myelinated axons and glial cells in rat central nervous system

The distribution of elements (e.g. Na, Cl, K) and water in CNS cells is unknown. Therefore, electron probe X-ray microanalysis (EPMA) was used to measure water content and concentrations (mmol/kg dry or wet weight) of Na, Mg, P, S, Cl, K and Ca in morphological compartments of myelinated axons and glial cells from rat optic nerve and cervical spinal cord white matter. Axons in both CNS regions exhibited similar water content ( 90%), and relatively high concentrations (wet and dry weight) of K with low Na and Ca levels. The K content of axons was related to diameter, i.e. small axons in spinal cord and optic nerve had significantly less (25–50%) K than larger diameter axons from the same CNS region. The elemental composition of spinal cord mitochondria was similar to corresponding axoplasm, whereas the water content (75%) of these organelles was substantially lower than that of axoplasm. In glial cell cytoplasm of both CNS areas, P and K (wet and dry weight) were the most abundant elements and water content was approximately 75%. CNS myelin had predominantly high P levels and the lowest water content (33–55%) of any compartment measured. The results of this study demonstrate that each morphological compartment of CNS axons and glia exhibits a characteristic elemental composition and water content which might be related to the structure and function of that neuronal region.     

Inherited Neurodegenerative Disorders Caused by CAG/Polyglutamine Tract Expansions: Symposium Introduction

At the beginning of this decade, the American Association of Neurology decided that the 1990's should be labelled "the decade of the brain" for expected advances in our understanding of neurological disorders and neuroscience. By the end of this decade, clinicians and researchers who work in the field of inherited neurological disorders might well remember the 1990's as "the decade of the trinucleotide repeat". At the time of writing this introduction, eleven inherited neurological disorders have been found to be caused by expansions of trinucleotide repeats, and a twelfth trinucleotide repeat expansion mutation has been identified (6), although the gene containing this mutant triplet repeat has not been cloned to our knowledge (Table 1).     

Allergic contact sensitizing chemicals as environmental carcinogens.

Chemicals that were bioassayed by the National Toxicology Program (NTP) and that also produce allergic dermatitis (ACD) in humans were evaluated for their tumorigenic characteristics. The impetus for the study was that most contact sensitizers, i.e., those that produce ACD, and genotoxic carcinogens are chemically similar in that they are electrophilic, thereby producing adducts on macromolecules including protein and DNA. This similarity in chemical behavior suggests that many contact sensitizers might be environmental carcinogens. All of the published NTP bioassays by early 1996 that had both genotoxicity and carcinogenicity studies were included in this analysis. The NTP chemicals had been chosen for bioassay without regard to their ability to produce ACD. Of the 209 chemicals that were bioassayed, there were 36 (17%) that were known to be human contact sensitizers; about half of these were positive on tumor bioassays. The contact sensitizers differed from the NTP sample as a whole by having a proportionately larger number of nongenotoxic chemicals by the Ames Salmonella assay, presumably because more of them were selected on the basis of widespread usage rather than structural resemblance to known carcinogens. Compared to the nongenotoxic chemicals, the genotoxics were stronger carcinogens in that they had a higher incidence of positive tumor bioassays, with twice the number of organs in which tumors were induced. The nongenotoxic chemicals had a preference for tumor induction in parenchymal tissues in contrast to epithelial tissues. The contact sensitizers showed essentially the same characteristics as the whole NTP sample when stratified according to genotoxicity. Judging by the chemicals that were chosen primarily for their widespread use rather than for their structural resemblance to carcinogens, the addition of a test for contact sensitization to the Ames test as a screening tool would increase the tumorigenic detection efficiency by about 40% because of the nongenotoxic tumorigens. A ballpark estimate suggests that there could be several thousand contact sensitizers for humans in commercial use that are rodent tumorigens.     

Papillitis and vasculitis of the arteria spinalis anterior as complications of hepatitis C reinfection after liver transplantation

It is well known that hepatitis C virus (HCV)-related chronic liver disease may be associated with various immunological disorders including mixed cryoglobulinemia, which is accompanied by cutaneous vasculitis, arthralgias, membranoproliferative glomerulonephritis, and neuropathy in association with cryoprecipitable immune complexes in serum. We describe here the first case of central nervous system HCV infection with evidence of the virus in the cerebrospinal fluid in association with cryoglobulinemia in a patient who developed recurrent episodes of papillitis and vasculitis of the arteria spinalis anterior after liver transplantation. Received: 3 September 1996 Received after revision: 13 November 1996 Accepted: 6 December 1996     

Tensile strength of plate osteosynthesis. Comparative biomechanical study of the original autocompression plate and a functional modification using the ZESPOL principle

In order to overcome the problems of stress protection and pressure atrophy of bone, which are associated with the traditional plating technique, in Poland a modified type of plating, ZESPOL has been, developed. In this procedure, the plate is not screwed onto the surface of the bone, but is fixed above the bone by special platform screw bolts in a comblike construction. This paper describes an experimental biomechanical investigation, using cadaver tibia, which compares the stability of the ZESPOL principle with that of the traditionally applied autocompression plate (ACP). In order to make the system biomechanically comparable, instead of the original ZESPOL plates, which are different in dimension, an ACP was used that was specially adapted to fit the ZESPOL criteria. Compared to the ACP, the bending stability of the ZESPOL osteosynthesis was found to be significantly less. When the same stress was applied, the total bending capacity of the ZESPOL system was found to be between 9% and 1348% higher, depending on the position of the plate and the direction of the force applied. In addition, the gap of the osteotomy site was between 6% and 923% greater with the ZESPOL system. Deformation of the bone adjacent to the osteotomy site was more closely approximate to intact bone with ACP than with ZESPOL plate. Our evaluations show that the ZESPOL system has less bending stability than ACP, without having the advantage of a more physiological bone-bending curve. However, the stability of the new system can be regarded as being overall sufficient.     

Treatment of iatrogenic biliary obstruction by balloon dilatation of a biliary jejunal fistula

Biliary obstruction and multiple hepatic abscesses occurred in a patient after ligation of a segmental branch of the right hepatic duct. The patient was successfully managed by transhepatic biliary drainage and balloon dilatation of an internal fistula that developed between the ligated duct and a Roux limb of jejunum. Internal biliary fistulas may be dilated using interventioanl radiologic techniques to permit nonobstructed bile flow. Implications for the nonsurgical treatment' of biliary strictures are discussed.     

Pectus excavatum defect on liver-spleen scintigraphy

A 58-year-old man with a pectus excavatum demonstrated a photon-deficient defect within the left lobe of the liver on liver-spleen scintigraphy using Tc-99m SCOL. Computed tomography of the liver clearly revealed the abnormal defect seen on the liver-spleen scan to be due to the pectus excavatum. This case confirms the impression that these skeletal aberrations may cause false-positive hepatic defects.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense     

The in vitro elution characteristics of vancomycin and tobramycin from calcium sulfate beads

The purpose of this study was to determine the elution characteristics of vancomycin and tobramycin when mixed with calcium sulfate to form antibiotic beads. Calcium sulfate was combined with vancomycin and tobramycin separately to form 2 types of antibiotic beads, which were packaged and labeled separately. The packaged calcium sulfate beads with vancomycin and tobramycin were then gas sterilized. The beads were placed in phosphate-buffered saline and kept at 36 degrees C for 6 weeks. Two separate series of assays were run simultaneously for both types of beads. In one assay, a bead containing vancomycin was placed in a fresh vial of phosphate buffered saline after each assay. The same was done with beads containing tobramycin. In the second series of assays, 9 vials of phosphate buffered saline each containing 1 vancomycin bead and 9 vials of phosphate buffered saline each containing 1 tobramycin bead was arranged. The phosphate-buffered saline was then assayed at predetermined times for both the vancomycin bead series and the tobramycin bead series. The amount of vancomycin and tobramycin assayed nearly equaled the calculated amount of antibiotic per bead measured before bead construction. Also, the elution of antibiotic from the calcium sulfate was complete within 72 hours. In conclusion, the construction and gas sterilization of calcium sulfate beads containing vancomycin and tobramycin does not destroy vancomycin and tobramycin. Also, the complete elution of available vancomycin and tobramycin in calcium sulfate beads occurs within 72 hours.