Eye-movements and sequential tracking in dyslexic and control children

The efficiency of eye-movements while tracking sequential lights was compared for 15 dyslexic children and 15 controls, matched on age and non-verbal intelligence. Contrary to Pavlidis (1981), no significant differences were found between the two groups on two measures of efficiency. A hierarchical cluster analysis did not demonstrate unique patterns of errors for dyslexics, with the exception of a single female dyslexic.

Effects of dietary magnesium deficiency on thallium-20 1 kinetics and distribution in rat myocardium: concise communication

Kinetics and distribution of TI-201 were studied in myocardium of rats with chronic dietary induced Mg deficiency. Rats were fed the Mg-deficient diet for 30 days and were then injected intravenously with 0.2 mCi of TI-201. Comparable control animals were fed a standard laboratory diet. One-half hour after injection, rats were killed and a segment of myocardium was washed with nonradioactive Krebs solution in a special chamber. Radioactivity in the tissue was recorded continuously for 1 hr. A three-compartment model (extracellular, main intracellular, and subcellular) was found to describe adequately the kinetics of TI-201. In myocardium of Mg-deficient animals, significant changes in values of transport rate constants and compartment sizes for TI-201 indicated a moderate decrease in extracellular compartment and a threefold enlargement in subcellular compartment (presumably mitochondrial) at the expense of the main intracellular compartment, which underwent a marked reduction. Bulk TI-201 uptake in myocardium of Mg-deficient rats was unchanged. The findings are interpreted as being consistent with mitochondrial alterations reported in Mg-deficient animals. Clinical implications are discussed.

Free cytoplasmic calcium concentration and the mitogenic stimulation of lymphocytes

The effects of the lectins concanavalin A, succinylated concanavalin A, and wheat germ agglutinin on the free cytoplasmic Ca2+ concentration in mouse thymocytes were measured using the fluorescent Ca2+ indicator "quin 2" (Tsien, R. Y. (1980) Biochemistry 19, 2396-2404) and compared with the metabolic and mitogenic effects of the lectins on the cells. Within 1 min of adding each ligand, there is a dose-dependent increase in the free cytoplasmic Ca2+ concentration reported by quin 2. This response is selective for Ca2+, but it does not coincide closely with the subsequent mitogenic stimulation at 48 h by concanavalin A or succinyl concanavalin A. The nonmitogenic lectin wheat germ agglutinin also causes an increase in free cytoplasmic Ca2+ concentration and early metabolic stimulation of the cells, but stimulation is self-aborted before DNA synthesis occurs. At the intracellular concentrations of quin 2 required for measurement of the free Ca2+ concentration, the chelator causes early metabolic stimulation of the cells very similar to that produced by concanavalin A and the mitogenic Ca2+ ionophore A23187. Thus, phosphatidylinositol metabolism and lactate production are stimulated in mouse thymocytes and pig lymphocytes within 1 h of loading with quin 2 and significant increases in RNA synthesis occur after 8 h. Quin 2 causes mitogenic stimulation of pig lymphocytes measured as increased [3H]thymidine uptake at 48 h, that is variable but substantial in most experiments (up to 100% of the stimulation by A23187). The chelator itself has no significant activity as a Ca2+ ionophore, but the apparent free Ca2+ concentration in the cells increases both with the concentration of intracellular quin 2 and with the extracellular Ca2+ concentration. These data leave open the possibility that quin 2 itself affects the concentration of free Ca2+ or other cations in the cells.

Some effects of aldosterone on sodium kinetics and distribution in porcine arterial wall

Transport rate constants for Na+ exchanges and relative Na+ compartment distribution in isolated pig carotid wall were determined with the aid of 22Na+ as tracer that was continuously washed out. A three-compartment model consisting of 1) extracellular, 2) intracellular, and 3) subcellular spaces was found to represent adequately the kinetics of 22Na+. It was found that d-aldosterone (0.85 X 10(-6) M) added to the incubating medium for 3 h causes significant changes in two transport rate constants and in the distribution of sodium within different compartments. Total tissue water, nonradioactive sodium (tracee), and potassium are not altered by aldosterone; however, when amounts of Na+ tracee are calculated for each compartment, aldosterone significantly reduces the amount of Na+ in compartment 2. Overall, the results indicate that aldosterone induces a translocation of Na+ into the extracellular space at the expense of the intracellular space. The findings are interpreted in the light of recent reports on the role of altered function of the Na+-K+ pump under aldosterone influence or arterial hypertension.

Sensitive assay, based on hydroxy fatty acids from lipopolysaccharide lipid A, for Gram-negative bacteria in sediments

Biochemical measures have provided insight into the biomass and community structure of sedimentary microbiota without the requirement of selection by growth or quantitative removal from the sediment grains. This study used the assay of the hydroxy fatty acids released from the lipid A of the lipopolysaccharide in sediments to provide an estimate of the gram-negative bacteria. The method was sensitive to picomolar amounts of hydroxy fatty acids. The recovery of lipopolysaccharide hydroxy fatty acids from organisms added to sediments was quantitative. The lipids were extracted from the sediments with single-phase chloroform-methanol extraction. The lipid-extraction residue was hydrolyzed in 1 N HCl, and the hydroxy fatty acids of the lipopolysaccharide were recovered in chloroform for analysis by gas-liquid chromatography. This method proved to be about fivefold more sensitive than the classical phenol-water or trichloroacetic acid methods when applied to marine sediments. By examination of the patterns of hydroxy fatty acids, it was also possible to help define the community structure of the sedimentary gram-negative bacteria.

Diffusional and compartmental models for tracer washout records of Na in dog carotid

This paper re-examines studies of Na kinetics in canine carotid arterial wall previously reported by three groups of investigators. The similarities and differences in experimental and analytical approaches for Na arterial wall washout therein are reviewed. Major conclusions are: (1) A three-compartment model in series is adequate for all short and long (after subtracting the small slow exponential) records. (2) Values for the diffusion coefficient, however, varied markedly among the different groups. (3) A continuous sampling method as opposed to an intermittent one measures better the kinetics of a rapidly exchanging ion as Na+. (4) Models based on individual washout records are better than those based on ensemble averaging. Characterization of sets of results in terms of mean values for comparing parameters provides significant potential for distinguishing quantitative features between control and treated sets despite inadequacies in data sampling or model specifications.

Voice analysis of the effects of benzodiazepine tranquillizers

The voice characteristics measured by the Psychological Stress Evaluator (PSE) were investigated in patients taking widely prescribed tranquillizers. It was found that not only was the PSE affected by medication, but that the effects were different for two different benzodiazepines. Implications for the PSE as a psychophysiological measure are discussed.

High-pressure liquid chromatographic determination of amitriptyline and its major metabolites in human whole blood

A sensitive, specific, high-pressure liquid chromatographic method using an internal standard was developed for the determination of amitriptyline and its major metabolites in whole blood. Analysis was carried out on a microparticulate silica column with a mobile phase consisting of acetonitrile-methanol-aqueous ammonium hydroxide (93:7:0.4). Linear calibration curves ranging to 250 ng/ml were obtained for all compounds using UV absorbance detection at 220 nm. The lower limit of detection was 2 ng/ml for amitriptyline and 10-hydroxyamitriptyline, and 6 and 16 ng/ml for nortriptyline and its 10-hydroxylated metabolite, respectively. Human whole blood samples collected after single intravenous and single oral doses can be analyzed using this procedure.

Characteristics of the release of the surface coat protein from bloodstream forms of Trypanosoma brucei

Bloodstream forms of the African trypanosomes undergo antigenic variation in their mammalian host. This process involves removal of the existing variant coat protein and its replacement with another. The mechanism by which the surface coat protein is released to the external supporting medium has been shown to depend in vitro specifically on the presence of calcium ions together with the calcium ionophore. A-23187, and to be inhibited by Zn2+. Release of the surface coat protein was not stimulated by conditions designed to alter the plasma membrane potential or the major ionic gradients across that membrane. Release could be stimulated by inhibiting the energy metabolism of these glycolysing cells with 2-deoxyglucose, which probably prevents the energy-dependent mechanisms that normally keep the cytoplasmic Ca2+ concentration low. These results and the finding that the release process was strongly temperature dependent suggested the possible mediation of some as yet undefined enzymatic reaction.

Myocardial kinetics and organ distribution of thallium-201 in two different age groups of rats

Effects of aging were investigated on kinetics and distribution of 201 thallium (201TI) in isolated myocardial tissue and other organs of rats after injection in vivo of this radionuclide. Older rats showed a trend toward lesser organ uptake, but this was statistically significant only in kidneys, fat, and fur. Experimental outflow curves for 201TI from isolated myocardial wall segments revealed a sustained higher level of 201TI in the older rats throughout the outflow. Further analysis of the washout kinetics with a three-compartment model (extracellular, intracellular, and subcellular) showed a significant reduction of extracellular compartment and increase of subcellular compartment in older rats. The extracellular to overall intracellular ratio also decreased significantly in the older rats. The changes found for 201TI in extracellular and subcellular myocardial compartments in older rats at rest are also similar to those seen in myocardium of young rats after exercise. It is concluded that, although aging has effects on distribution of 201TI in myocardium, such effects are not likely to impair the quality of myocardial scintigraphy in older patient

Myocardial K kinetics in rats on Mg-deficient diet

Kinetics and distribution of K were studied in myocardiuum of chronic Mg-deficient rats. The experimental design was as follows. Rats were fed either Mg-deficient or control diet for 30 days. They were then injected with 0.2 mCi of K-43. One half hour after injection they were killed and a segment of myocardium was washed with nonradioactive Krebs solution in a special chamber. Radioactivity remaining in the tissue was recorded continuously for 1 hour. A three-compartment model (extracellular, main intracellular, and subcellular) was used; transport rate constants (kij) and relative compartment sizes (qj) were determined. In myocardium of Mg-deficient rats the kij's and q's indicated greatly reduced intracellular accumulation of K but a large accumulation of K within the subcellular compartment probably mitochondrial. There was also some enlargement of the extracellular compartment. The extracellular to overall intracellular ratio for K increased 46% in Mg-deficient myocardium. The hypothesis that dietary Mg deficiency affects Na-K pump function is discussed.

Effects of oil and gas well-drilling fluids on the biomass and community structure of microbiota that colonize sands in running seawater

Well-drilling fluid and a number of the known components (barite, clay, Aldacide, Surflo, and Dowicide, were tested for effects on the biomass and community structure of the microbiota that colonize marine sands exposed for eight weeks to running ambient seawater. Shading the microbiota from light depressed the microflora without a significant effect on the biomass, while well-drilling fluids layered on the surface or mixed with the sand significantly increased a component of the bacteria and the microfauna as reflected in changes in the fatty acid composition. There were some shading effects from the surface layering of well-drilling fluids as reflected in the fatty acids from the microflora when compared to the sands mixed with well-drilling fluids. Barite had essentially no effect on the biomass or community structure while clays increased nearly all of the biomass indicators for the bacteria as well as the microfauna; the clay overlay mirrors the effect of the drilling fluids. Aldacide shifted the bacterial composition, depressing the proportions of microbes containing the cyclopropane fatty acids and the anaerobic pathways of desaturation. Concentrations of 1 and 15 microgram/L increased the bacterial biomass as reflected in the total lipid (16:0) and extractable lipid phosphate coupled with a decrease in the total microeukaryotes. Surflo increased the biomass and shifted the bacterial community structure at concentrations between 4 and 800 microgram/L. The lowest level also stimulated the microfauna. Dowicide at 100 microgram/L increased the bacteria forming cis-vaccenic acid and the microfauna similar to low concentrations of Surflo.

Synthesis and metabolic clearance of 1,25-dihydroxyvitamin D as determinants of serum concentrations: a comparison of two methods

We evaluated endogenous renal 1,25-dihydroxyvitamin D (1,25-OH)2D) synthesis by compartmental analysis of the plasma disappearance of injected [3H]1,25-dihydroxyvitamin D3 in 11 subjects with serum 1,25-(OH)2D concentrations varying from 9-154 pM (normal, 89 +/- 25 pM). Estimated renal synthesis ranged from 2-180 pmol/kg . day. Serum 1,25-(OH)2D concentrations in these subjects best fit a log function of renal synthesis: serum 1,25-(OH)2D, pM = -13 + 74 log renal 1,25-(OH)2D production, picomoles per kg/day (r = 0.91). We also evaluated serum 1,25-(OH)2D concentrations in 6 healthy subjects who had been given 0.6, 1.2, or 1.8 nmol calcitriol every 6 h during a period 6--12 days after hormone administration was begun. Steady serum 1,25-(OH)2D concentrations 2, 4, and 6 h after the last calcitriol dose were achieved in proportion to log dose: serum 1,25-(OH)2D, pM = -12 + 103 log 1,25-dihydroxyvitamin D3 dose, picomoles per kg/day (r = 0.94). Estimated 1,25-(OH)2D production rates using these two methods and assuming a normal serum 1,25-(OH)2D concentration of 89 pM range from 10--24 pmol/kg . day or, for a 70-kg subject, 0.6--1.7 nmol/day or 0.25--0.7 microgram/day. Metabolic clearance of 1,25-(OH)2D appears to be accelerated when production rates are increased.

Cholesterol in sarcoplasmic reticulum and the physiological significance of membrane fluidity

Vesicles of sarcoplasmic reticulum from rabbit muscle can be loaded with cholesterol to at least 20 mol% with respect to endogenous sarcoplasmic-reticulum phospholipid without effect on the ATPase activity at 32 degrees C. This applies both to sarcoplasmic-reticulum vesicles in which the ATPase activity is stably coupled to Ca2+ accumulation, and to sarcoplasmic-reticulum vesicles in which the sarcoplasmic-reticulum ATPase is activated severalfold by fully uncoupling the enzyme from net Ca2+ accumulation. Since the incorporation of cholesterol causes a large decrease in fluidity of sarcoplasmic-reticulum phospholipid bilayer, these results for sarcoplasmic reticulum raise the more general question of whether bilayer fluidity is important in modulating the function of membrane proteins under physiological conditions as is widely assumed, or whether the function of membrane proteins may be effectively buffered under normal operating conditions against changes in bilayer fluidity due to extraneous agents.

Effects of exercise on kinetics and distribution of K-43 and Tl-201 in isolated myocardium: concise communication

Kinetics and distribution of K-43 and Tl-201 were studied in isolated myocardial tissue from rats to assess the effects of exercise. The experimental design was as follows. Rats in some groups were forced to swim for 2 hr; immediately after swimming, they were injected with 0.2 mCi of 43KCl or 201TlCl; at 0.5 or 3 hr after injection they were killed and a myocardial segment was obtained and subjected to washouts with nonradioactive Krebs fluid in a special chamber. The radioactivity remaining in the tissue was recorded continuously for 1 hr. In control groups ("rested") the exercise was omitted. Altogether there were four groups of ten animals each for both K-43 and Tl-201. A three-compartment model (extracellular, main intracellular, and subcellular) was used; transport rate constants and relative compartment sizes were determined. The most striking finding was the unchangeability of K-43 parameters with regard to experimental condition (rest compared with exercise) and sampling time (0.5 compared with 3 hr after radionuclide injection). On the other hand, Tl-201 parameters were modified by exercise and sampling time. Notable differences between K-43 and Tl-201 kinetics were found. The hypothesis that alterations at the cellular level may affect regional myocardial distribution of a radionuclide is discussed.

Effect of Silicate Grain Shape, Structure, and Location on the Biomass and Community Structure of Colonizing Marine Microbiota

Microbiota colonizing silica grains of the same size and water pore space, but with a different microtopography, showed differences in biomass and community structure after 8 weeks of exposure to running seawater. The absence of surface cracks and crevices resulted in a marked diminution of the total microbial biomass measured as lipid phosphate and total extractable palmitic acid. With increasing smoothness of the sand grain surface, examination of the community structure showed a marked decrease in procaryotes and algal microeucaryotes, with a relative increase in microeucaryotic grazers. A comparison of the colonizing sediment incubated in running seawater or at 32 m on the sea floor with a sediment core showed a decreased bacterial biomass with a different community structure and a decreased total microeucaryotic population of both grazers and algae. The quantitative differences in microbial biomass and community structure between the microcosms and the actual benthic population in the core were determined.

Transbilayer distribution of lipids in a population of sarcoplasmic-reticulum vesicles sealed with their cytoplasmic side outwards

A population of sarcoplasmic-reticulum vesicles, all of which were sealed with their cytoplasmic side outwards, was obtained by density-gradient centrifugation after loading the vesicles with calcium oxalate. The calcium oxalate could subsequently be removed from the vesicles by the reverse action of the calcium-transport system. Measurements of the catalysed exchange of the phosphatidylcholine in the sarcoplasmic-reticulum cytoplasmic monolayer with an exogenous phosphatidylcholine pool suggested that phosphatidylcholine is symmetrically distributed across the sarcoplasmic-reticulum membrane. A similar result was obtained for phosphatidylethanolamine when sarcoplasmic-reticulum lipids were labelled with trinitrobenzenesulphonic acid. Further catalysed lipid-exchange reactions showed that the transverse movement of phosphatidylcholine across the membrane was exceedingly slow (t 1/2 greater than 15 days).

The effect of bilayer thickness on the activity of (Na+ + K+)-ATPase

The activities of purified (Na+ + K+)-ATPase supported by a series of phosphatidylcholines with monounsaturated (cis-9) fatty acyl chains (di(n : 1) phosphatidylcholine) varying in length from n = 12 to n = 23 were determined by the lipid titration technique. The ATPase activity at 20 degrees C decreased from 2.9 to 0.1 mumol/min per mg protein as n was decreased from 16 to 12 and decreased from 2.9 to 1.0 mumol/min per mg protein as n was increased from 20 to 23. In further experiments, the di(n : 1) phosphatidylcholine-ATPase complexes were treated with increasing proportions of n-decane, which has been shown previously to increase the thickness of black lipid membranes. n-Decane caused a large increase (greater than 20-fold) in activity of the short-chain complexes (n = 12,13); for n = 14--18, the ATPase activity first increased and subsequently decreased as the proportion of decane was increased, and for n = 20 or 23 decane caused a progressive decrease in activity with increasing concentration. These effects confirm qualitatively that a major factor determining the activity in each bilayer is its thickness. This behaviour closely parallels that of the (Ca2+ + Mg2+)-ATPase of sarcoplasmic reticulum [1] and suggests that a major class of trans-membrane transport proteins may have a similar dependence on bilayer thickness.

Differences between 201Tl and 43K tissue distribution in rested and exercises rats

A comparison is made of relative organ-to-plasma uptake of 43K and 201Tl in rats at rest and after exercise (two hour swimming). Organs were obtained 0.5 or 3 hrs after radionuclide injection. Thus, there were four groups each for 43K and 201 Tl. For 201Tl the triad kidneys-heart-adrenals was very consistent throughout the four experimental situations in showing the highest uptake, whereas for 43K adrenals-heart-liver predominated at 0.5 hrs and thymus-liver at 3 hrs. The ratio 201Tl/43K in myocardium was always greater than unity in all four experimental situations. The heart-to-lung and heart-to-liver uptake ratios were lower in all cases for 43K vs. 201Tl. One of the most important findings was that exercise always determined an increase of these ratios for 201Tl, but it had an unfavorable effect on the 43K heart/lung ratio and no definite effect on the 43K heart/liver ratio. Our findings are analyzed in the light of previous publications. It is concluded that these two ions have biologically important different characteristics and that excessive and seemingly unjustified emphasis has been made on their physiological similarity.

Organ-to-plasma uptake ratio of T1-201 in rats injected at rest or after strenuous exercise. An attempt to interpret the so-called redistribution of myocardial T1-201

A comparison is made of relative organ-to-plasma T1-201 uptake in rats at rest and after exercise (2 h swimming). Organs were obtained 1/2 or 3 h after T1-201 injection. Under the four experimental conditions, the largest uptake was found in kidneys, heart and adrenal glands. The post-exercise to rest ratio of myocardial uptake is in agreement with clinical data reported in the literature. Two extensive tissues, skeletal muscle and fat, showed a remarkable increase of T1-201 uptake at 3 h as compared to 1/2 h in both rested and post-exercised animals. During the same time interval there was a temporal "washout" of T1-201 from heart (both at rest and after exercise) and kidney (after exercise only). The findings do not support the view of a delayed myocardial uptake phase of T1-201 during which T1-201 would be reintroduced into the blood from other body organs.

Partition of thallium-201 in isolated myocardial tissue of rats previously injected at rest or after exercise

The kinetics and distribution of TI-201 in isolated myocardial tissue of rats injected i.v. with this radionuclide are compared at rest and after exercise (2 hr of forced swimming). At 1/2 and 3 hr after injection, a myocardial segment was obtained and subjected to continuous washout with the radioactivity remaining in the tissue recorded each 10 sec for 1 hr. Altogether there were four groups of ten animals each. A three-compartment model (extracellular, main intracellular, and subcellular) was found to describe adequately the kinetics of TI-201. In the groups studied 1/2 hr after TI-201 injection the most dramatic effect of exercise was a translocation of TI-201 into the subcellular compartment. The change was also present but less marked in samples from exercised rats obtained 3 hr after TI-201 injection, which suggests a transition to the resting stage. The findings suggest the possibility of structural subcellular differences in myocardial uptake for TI-201 in clinical images visualized after exercise and at rest.

Multiexponential and multicompartmental approaches for analysis of tracer washout data from animal

A comparison is made between multiexponential and multicompartmental analyses of tracer washout data from biological tissues. Various analytical and computer methods are used to explore the relations between kinetic parameters of three-compartment models and parameters of three-exponential functions fitted to typical observed tracer washout records and also to examine relations between kinetic parameters of the same three-compartment models determined analytically and numerically. It is concluded that exponential factors and coefficients cannot always be equated respectively with conpartmental transport rate constants or compartment sizes. Sufficient analytical and computer methodologies exist so that selection of meaningful biological models should not be hampered by a lack of appropriate solution procedures.

Introductory remarks regarding facial plastic and reconstructive surgery

Some of the components of the author's training program at UCLA and in his actual practice in San Diego are compared, the type of surgical cases completed in training and in practice are examined, and the community acceptance of the author's definition of an otolaryngologist is commented on. Some of the conclusions regarding residency programs may be different from those of other specialists. The author's perspective is as a clinical assistant professor one year out of residency with an acute interest in the preparation for actual practice.

Experience with the Ribeiro reduction mammaplasty technique

The advantages and disadvantages of the Ribeiro reduction mammaplasty are cited. It is a very good technique when used with the described modifications in properly selected patients.

Sodium distribution in mesenteric arterial wall of rats with hypertension induced by drinking saline

1. Hypertension was induced in rats by substituting 2% (w/v) sodium chloride solution for drinking water. Sodium distribution in isolated mesenteric arterial wall was studied with the aid of 22Na, which was continuously washed out. Data were analysed by digital computer simulation without recourse to ancillary chemical measurements of extracellular space.

2. A three-compartment model consisting of (i) extracellular, (ii) intracellular and (iii) subcellular space was found to represent adequately the kinetics of 22Na. Transport rate constants were chosen as primary parameters describing intercompartmental sodium exchanges; the ratio of extra- to intra-cellular sodium compartments was calculated.

3. Results show the following significant changes in mesenteric arterial wall of salt-loaded hypertensive rats: (i) slowed sodium turnover; (ii) a decrease of the transport rate constant, which is presumed to reflect sodium movements from the intra- to the extra-cellular compartment; (iii) an increase of the transport rate constant, presumed to reflect sodium movements from the extra- to the intra-cellular compartment; (iv) a diminution of the extra- to intra-cellular compartment ratio for sodium.

4. The results suggest net movement of sodium into the cells; this change may be relevant to smooth muscle contraction and hence to the pathogenesis of blood pressure elevation in this model.

Factors influencing plasma concentrations of ethosuximide

The relation between steady-state plasma ethosuximide level and drug dose was studied in 46 patients. In this population, plasma drug levels were proportional to drug dose, expressed on a body weight basis. Age did not alter this relationship, but plasma levels increased more rapidly, relative to dose, in females than in males. Intake of methylphenobarbitone, but not intake of certain other anticonvulsants (phenytoin, phenobarbitone, primidone and carbamazepine) altered the relationship between plasma ethosuximide level and ethosuximide dose. In individual patients, successive dose increments of equal size produced progressively greater increases in steady-state plasma ethosuximide levels. This phenomenon has obvious therapeutic implications.

The comparative bioavailability of carbamazepine in 100 mg and 200 mg tablets

1. The bioavailabilities of carbamazepine in 100 mg and 200 mg tablets have been compared in a cross-over study of six subjects after two 600 mg doses of the drug, the different preparations being taken at 3 week intervals. 2. Areas under the plasma level curves, absorption rate constants and times to achieve peak plasma levels showed little difference between the two preparations. These findings suggest similar rates and extents of bioavailability of carbamazepine in the two preparations. 3. Calculated mean absorption and elimination parameters for carbamazepine were as follows: kabs = 0.1081 h-1, (s.d. = 0.0289); Tmax = 23.39 h, (s.d. = 8.66); k = 0.0191 h-1, (s.d. = 0.0033); VD = 0.989 1/kg, (s.d. = 0.159); and clearance = 0.0185 1/kg h, (s.d. = 0.0015).

Degenerate perturbations of protein structure as the mechanism of anaesthetic action

The interaction of the n-alkanols with lipid bilayers and excitable membranes shows that there is no simple correlation between conduction block and any of the perturbations of bilayer structure currently proposed as unitary mechanisms of local anaesthetic action. We propose instead that the n-alkanols act by direct interaction with target proteins to cause perturbations which depend directly on the precise structure of the alcohol.