Fiber analysis of human ventral and dorsal roots on the basis of different acetylcholinesterase activity]

Marked differences in the AChE activity of myelinated nerve fibers of ventral and dorsal roots could be established in human post mortem material. After a fixation time of 3 h and a critical incubation period of 24 h, in the mean 96% of the myelinated ventral root but only 4% of dorsal root fibers showed reaction product, detectable by the light microscope. The percentage of stained fibres varies, to some extent, in the different segments. Groups of very thin myelinated fibres within the ventral roots between the segments C-8 and L-3, showing a conspicuous high enzyme activity, are interpreted as pre-ganglionic sympathetic fibres; similar elements in the sacral ventral roots may represent parasympathetic fibres. The method of Karnovsky, applied under conditions established in this study, can be used for analysis of fibre types in a given human peripheral nerve.     

Nucleosome-associated protein kinases in murine erythroleukemia cells.

Chromatin subunits from murine erythroleukemia cells were prepared by a method which releases actively transcribing genes. Two casein kinase activities (CK₁ and CK₂) were isolated from these nucleosomes by gel nitration in 0.5 m NaCl. CK₁ (M_r ~ 200,000) and CK₂ (M_r ~ 35,000) were further purified by phosphocellulose chromatography and characterized with regard to several parameters which may regulate their activity in vivo. CK₁ has an NaCl optimum of 0.14 m, utilizes GTP as phosphate donor ~25% as efficiently as ATP, and phosphorylates a discrete group of high molecular weight nonhistone proteins in the unfractionated chromatin starting material. CK₂ has an NaCl optimum of 0.24 m, cannot utilize GTP, and modifies a different group of nonhistones. Both kinases are inhibited by concentrations of hemin (<50 μm) which efficiently induce globin gene expression in erythroleukemia cells. A histone kinase resolved during the gel filtration step is unaffected by hemin. An investigation of the mode of hemin inhibition reveals that CK₁ and CK₂ interact in different fashions with the inhibitor.     

Single channel gating events in tracer flux experiments I. Theory

Tracer ion flux measurements are a commonly used method for studying ion transport through membranes of cellular systems, where the rate of ion flow is determined by gating processes which control the opening and closing of transmembrane channels. Due to recent advances in the theoretical analysis of tracer flux from or into closed membrane structures (CMS), the mechanism of gating reactions can, in principle, be derived from flux data. A physically well founded analysis is presented for the dependence of the total tracer ion content of a collection of CMS on the gating processes. For functionally uncoupled gating units a mean single channel flux contribution [equation, see text] can be defined, where k is the intrinsic single channel flux coefficient, t the time over which flux is measured, and p(tau,t) is the probability that a given channel was open for a total period tau during t. This quantity reflects the mean time course of the tracer content due to flux through a single channel. Expressions for are derived that explicitly take into account a distribution in the lifetime of open channels. On the basis of the results, kinetic and thermodynamic parameters of multiphasic gating reactions can be determined from the time course of the overall tracer content in a colleciion of CMS.     

Enhanced virulence effect of K1 polysaccharide in neonatal rats challenged withE. coli

Purified K1 polysaccharide enhanced the virulence of non-K1Escherichia coli species when given by orogastric feeding to neonatal rats. Neonatal rats developedE. coli bacteremia when K1 polysaccharide was given concomitantly with non-K1E. coli, whereasE. coli bacteremia did not develop when non-K1E. coli was given alone.E. coli K1 species did cause bacteremia and meningitis when fed to neonatal rats. The mechanism by which k1 polysaccharide enhances virulence can be studied with this model of bacteremia development in neonatal rats.     

Comparison between penicillamine and sulphasalazine in rheumatoid arthritis: Leeds-Birmingham trial.

Sulphasalazine was first formulated by Svartz in the early 1940s, specifically for use as a remission inducing drug in rheumatoid arthritis. After the publication of an unfavourable trial, however, the drug was restricted to patients with ulcerative colitis. In the late 1970s sulphasalazine was re-examined in rheumatoid arthritis and favourable results reported in "open" trials. A double blind controlled trial was therefore conducted comparing enteric coated sulphasalazine and D-penicillamine in patients with active rheumatoid arthritis. A total of 63 patients were recruited in two centres; 31 were treated with sulphasalazine and 32 received penicillamine. After 16 weeks'' treatment both drugs had produced significant improvements in clinical score, pain score measured on a visual analogue scale, grip strength, Ritchie articular index, erythrocyte sedimentation rate, and serum C reactive protein concentration. Nausea was the major side effect in the sulphasalazine treated group. No potentially dangerous effects of sulphasalazine were encountered in contrast with those seen in the penicillamine group. The results suggest that sulphasalazine is an effective and safe drug capable of producing remissions in active rheumatoid arthritis. They also lend confidence to the use of preliminary "open" trials as a means of screening for remission inducing drugs in rheumatoid arthritis.     

Arsenazo I and tetramethylmurexide as optical calcium indicators

Calcium-binding stoichiometry, dissociation equilibrium constants at zero ionic strength (K⁰), and molar extinction difference coefficients (Δ?_λ) at the wavelength λ of the metallochromic indicators arsenazo I (ArsI) and tetramethylmurexide (TMX) were reevaluated with a computerized method based on mass conservation and thermodynamic consistency checks. This new method is shown to provide a more critical assessment of the assumed calcium-dye complexing model than is afforded by the commonly used reciprocal-plot method. The analyses of spectrophotometric Ca titrations confirm that both dyes form only 1:1 complexes in aqueous solution. For TMX, K⁰ = 1.3 × 10^?3m and Δ?₄₈₀ = 1.5 × 10⁴m^?1 cm^?1; for ArsI, K⁰ = 5.8 × 10^?3m and Δ?₅₆₂ = 1.8 × 10⁴m^?1 cm^?1 at pH 7.0 and T = 293°K. The discriminatory power of the analytical method is demonstrated by comparison of these results with those found for a different dye, arsenazo III, which complexes Ca in 1:1, 1:2, and 2:1 forms.