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The manipulation of stimulus significance, by instructions from the experimenter, may be taken as an example of verbal conditioning. Consideration of such a mechanism suggested that personality effects previously found in conditioning studies should be apparent in instructional manipulations of significance in a study of the orienting response (OR) to words. Because of recent changes in dimensioning of the personality structure, some of the items originally used to define Eysenck's extraversion (E) dimension are now used to assess the new dimension of psychoticism (P), suggesting that at least some of the established effects of E upon conditioning may be associated now with P. Hence the P scale was focused on in this study. Words differing on the evaluative dimension of the semantic differential were presented in three blocks, the first under indifferent instructions, the second under instructions to rate the words for their affective impact, and the third under indifferent instructions again. These blocks correspond to baseline, conditioning, and extinction conditions respectively. Electrodermal activity indicated enhanced conditioning, together with greater carry-over effects in the extinction phase, for low-P compared with high-P subjects. The results indicate the importance of personality effects in studies of stimulus significance and illustrate the value of the verbal conditioning mechanism in this area of the OR field. They also suggest the need to re-examine previously obtained E-effects in conditioning studies in light of changing personality tests.

A 50-cm fillet flap permitted above-knee amputation in lieu of hip disarticulation in a 20-year-old woman who had sustained severe injuries in a motorcycle accident. Although the flap was unusually long, the principles followed were the same as those for posterior flaps used in below-knee amputations and fillet flaps of the digits. The flap allowed preservation of maximal length in the residual limb and fully sensible skin coverage, both of which facilitated prosthetic usage.

The kinetic mechanism of yeast inorganic pyrophosphatase (PPase) was examined by carrying out initial velocity studies. Ca2+ and Rh(H2O)4(methylenediphosphonate) (Rh(H2O)4PCP) were used as dead-end inhibitors to study the order of binding of Cr(H2O)4PP to the substrate site and Mg2+ to the "low affinity" activator site on the enzyme. Competitive inhibition was observed for Ca2+ vs Mg2+ (Kis = 0.93 +/- 0.03 mM), for Rh(H2O)4PCP vs Cr(H2O)4PP (Kis = 0.25 +/- 0.07 mM), and for RH(H2O)4PCP vs Mg2+ (Kis = 0.38 +/- 0.03 mM). Uncompetitive inhibition was observed for Ca2+ vs Cr(H2O)4PP (Kii = 0.49 +/- 0.01). On the basis of these results a rapid equilibrium ordered mechanism in which Cr(H2O)4PP binding precedes Mg2+ ion binding is proposed. The inert substrate analog, Mg(imidodiphosphate) (MgPNP) was shown to induce Mg2+ inhibition of the PPase-catalyzed hydrolysis of MgPP. The Mg2+ inhibition observed was competitive vs MgPP and partial. These results suggest that Mg2+/MgPNP release from the enzyme occurs in preferred rather than strict order and that the Mg2+/MgPP-binding steps are at steady state. Zn2+, Co2+, and Mn2+ (but not Mg2+) displayed activator inhibition of the PPase-catalyzed hydrolysis of PPi (this study) and of Cr(H2O)4PP (W.B. Knight, S. Fitts, and D. Dunaway-Mariano, (1981) Biochemistry 20, 4079). These findings suggest that cofactor release from the low affinity cofactor site on the enzyme must precede product release and that Zn2+, Mn2+, and Co2+ (but not Mg2+) have high affinities for the cofactor sites on both the PPase.M.MPP and PPase.M.M(P)2 complexes. The role of the metal cofactor in determining PPase substrate specificity was briefly explored by testing the ability of the Mg2+ complex of tripolyphosphate (PPPi) (a substrate for the Zn2+-activated enzyme but not the Mg2+-activated enzyme) to induce Mg2+ inhibition of PPase-catalyzed hydrolysis of MgPP. MgPPP was shown to be as effective as MgPNP in inducing competitive Mg2+ inhibition (vs MgPP). This result suggests that the low affinity Mg2+ cofactor-binding site present in the enzyme-MgPP complex is maintained in the enzyme-MgPPP complex. Thus, failure of Mg2+ to bind to the enzyme-MgPPP complex was ruled out as a possible explanation for the failure of the Mg2+-activated enzyme to catalyze the hydrolysis of MgPPP.

In recent years, psychophysiologists have increasingly used the peripheral pulse as a more convenient source of cardiac information than the electrocardiogram. We explored some of the measurement problems associated with this choice by comparing estimates, produced by both data sources, of the cardiac response evoked by innocuous visual stimuli. The most important difference is that pulse transit time results in the immediately-prestimulus beat of a significant proportion of pulse-derived responses being mislabelled as the following beat, shifting the entire apparent response by one beat. This reduces correlations between the data streams, and has implications for the adequate measurement of evoked cardiac responses.

The biosynthetic reaction pathway leading to the natural product, 2-aminoethylphosphonate in Tetrahymena pyriformis has been elucidated. Incubation of [32P]PEP and [14C]PEP with T.pyriformis cellular homogenate fortified with Mg2+ and alanine/pyridoxal phosphate, yielded 2-aminoethylphosphonate as the minor reaction product (2-5% yield) and phosphoglycerate and pyruvate plus orthophosphate as the major products. Inclusion of thiamine pyrophosphate in the reaction mixture increased the yield of 2-aminoethylphosphonate by a factor of 10. Incubation of phosphonoacetaldehyde or phosphonopyruvate in the cellular homogenate also provided 2-aminoethylphosphonate. The cellular homogenate catalyzed the transformation of phosphonoacetaldehyde to 2-aminoethylphosphonate in an ca. 80% yield. However, the maximum yield of 2-aminoethylphosphonic acid obtained by use of phosphonopyruvate was only 15%. The major reaction pathways induced by treatment of phosphonopyruvate with the cellular extract involved its competitive conversion to PEP and pyruvate plus orthophosphate.

Dermatoglyphic comparisons were made among 32 autistic children aged from 4-10 to 18-11; sex-, age-, and IQ-matched retarded children; and sex- and age-matched normal children. Significant differences were found between the autistic and normal children for distribution of dermal patterns and ridge line disruption, but no significant differences were found for the total mean ridge counts or mean ridge count rankings. Apart from the right hand of the autistic children, there were no unusual scores for digital dispersion ratios. Autistic and retarded children differed only in their distribution of dermal patterns, with the autistic children apparently intermediate between retarded and normal groups. These results indicate that conclusions of unique congenital disturbance in the etiology of autism inferred from different dermatoglyphics may be premature, and that dermatoglyphics may be ineffective in delineating autistic children from other atypical populations.

In the assessment of the child with flat feet a sound knowledge of arch and subtalar biomechanics, epidemiology, and etiology is important. The occurrence and natural history of flat feet are presented, and treatment modalities that have withstood the test of time are discussed.

Evidence for the increasing recognition of maturational lag in addition to intellectual impairment, associated with the syndrome of early-onset psychosis, is presented to indicate that developmental variables play a central role in the behavioral profile of autistic children. The failure of research to give methodological consideration to control of these variables is discussed, and implications for the interpretation of results from experimental studies are outlined. It is suggested that the distinction between controlling not only for mental age but also for chronological age to facilitate the delineation of specific deficits in this syndrome.

Phasic changes in respiratory period, electrodermal activity (EDA), the evoked cardiac response (ECR), and the vasoconstrictive peripheral pulse amplitude response (PPAR), were examined in matched groups of autistic, retarded, and normal children, using repeated presentation of simple visual and auditory stimuli. Analysis as a function of group membership and age indicated that respiratory pause and EDA showed habituation in the retarded and normal groups, but not in the autistic group, with no age effects in any group. PPAR and ECR showed no habituation in any group, but within-group age differences, and a higher mean response level for the autistic subjects. The autistic children did not display the diminution of response level with increased age that was characteristic of both the control groups. These effects were obtained across both modalities. Results could not be attributed to between-group tonic cardiac arousal differences, and were interpreted as further indications of diminished sensitivity to reductions in stimulus novelty, as well as developmental delay, in early-onset psychosis.

Barry and O'Gorman (1987) employed a response-averaging technique to investigate the electrodermal orienting response (OR) to stimulus omission. We obtained reliable evidence of increased response latency to stimulus omission, supporting an explanation of the missing-stimulus effect in terms of Maltzman's voluntary OR. Wilson's (1989) commentary on our article addresses both methodological and theoretical aspects. This response first examines his methodological difficulties, and provides simulation exercises which serve as a validation of our procedure. We then examine Wilson's theoretical points. His alternative theoretical explanation of the missing-stimulus effect, in terms of a systematic bias in the time-keeper of the stimulus-comparator process, is shown to be untenable. His remaining problem, concerning what he terms "assessment of stimulus significance", appears to have arisen through misinterpretation of our theory. A clarification of our theoretical position indicates the internal consistency of our use of "significance" and "voluntary OR".

This study examined the use of the P scale of the Eysenck Personality Questionnaire as a pencil and paper estimate of level of affect lability. Groups of subjects differing on the P scale were presented with emotive and non-emotive words. High P (low affect) subjects appeared inhibited in their emotional rating of all words, and displayed a restricted range in their reporting of this rating. Further, the electrodermal activity elicited by these words differed between the groups, with high P subjects again appearing relatively inhibited. These results support the validity of the P scale as a measure of affect lability and have implications for a recent hypothesis of impaired functioning of the reticular activating system in early-onset psychosis. The results may also be interpreted to support the role of significance in elicitation of the orienting response.

1. Potentials across the mucosal and serosal membranes of the epithelial cells of rat jejunum together with transmural potentials were recorded using everted sac preparations.2. Ionic changes in either mucosal or serosal fluids affect mucosal or serosal membrane potentials respectively with comparable changes in the transmural potential. The contralateral membrane potential is relatively unaffected.3. Replacement of mucosal sodium chloride by potassium chloride or lithium chloride had little effect on potentials, but its replacement by mannitol or Tris chloride increased the negativity of the mucosal potential, giving linear relationships against log(10)[Na](m) with slopes of 41.4 and 30.7 mV respectively for tenfold change in [Na](m).4. At constant [Na](m), potassium or lithium increased the mucosal potential by 25.7 and 19.8 mV respectively for tenfold concentration changes.5. Qualitatively similar changes occurred in the serosal potential when the ionic composition of the serosal fluid was varied.6. Mucosal potential changes in response to modifications of the ionic composition of the mucosal fluid were the same in the presence and absence of galactose.7. Sodium and potassium diffusion potentials largely determine both the mucosal and serosal membrane potentials. For the mucosal membrane, P(K):P(Na) is 1.26:1, and is probably higher for the serosal membrane. Chloride makes no significant contribution to membrane potentials.8. Potentials generated by the electrogenic sodium pump are superimposed on diffusion potentials across the serosal membrane.

1. The transfer of propionate by sacs of rat everted intestine has been investigated in relation to a number of physico-chemical factors which affect movement of weak electrolytes.2. Neither the observed movement nor the distribution of propionate can be accounted for by the theory of non-ionic diffusion or by modifications of it, such as the microclimate hypothesis or partial permeability to ions.3. It is not possible to account for the observed propionate movement by the electrical potential across the gut or by solvent drag.4. The most satisfactory explanation for the observations is a transfer process in the gut for volatile fatty acids, and some features of this are discussed.

1. When mono-, di- and triacetins are incubated with sacs of rat everted intestine, they enter the epithelial cells and are hydrolysed to free glycerol and acetic acid.2. The rate-limiting step in the process is the entry of glyceride into the epithelial cell.3. The three acetins enter the epithelial cell at the same rate, and the mechanism of this remains unknown.4. The acetate released appears in higher concentrations on the serosal side, and the relation of this to the mechanism for transfer of volatile fatty acids is discussed.5. It is not necessary to postulate a special mechanism for entry of volatile fatty acids into the cell.

1. The nature of Na transfer across rat jejunum was studied by measuring the Na and fluid transfers and the electrical potential in the presence of galactose, mannose and glucose.2. Galactose, actively transferred but not metabolized, caused an increase in the potential but no change in Na transfer or tissue resistance.3. Mannose, not actively transferred but metabolized, caused a large increase in Na and fluid transfer without affecting the potential or tissue resistance. Similar results were obtained with glucose in the presence of phlorrhizin.4. Galactose in the presence of mannose increased fluid and Na transfer to the level found with glucose, which is both actively transferred and metabolized.5. These results are consistent with the view that there are two Na pumps associated with hexoses in rat jejunum, both moving Na towards the serosal side. One is an electrogenic pump, stimulated by hexose transfer, and which results in a rise in potential, and the other is a neutral pump which is stimulated by hexose metabolism and which does not affect the potential.

1. A study has been made of the effect of Na replacement in the incubation media on the hexose-dependent potential and the capacity of sacs of rat intestine to transfer fluid and galactose.2. Replacement of NaCl with mannitol or Tris Cl had little effect on the hexose-dependent potential, while replacement with LiCl and KCl had an inhibitory effect on the potential.3. Replacement with KCl, LiCl, mannitol and Tris Cl all reduced the capacity to transfer fluid and galactose, but the effects of Li and K replacement were greater than mannitol or Tris replacement.4. There is not a fixed relation between the magnitude of the potential and the amount of galactose transferred.

1. Stripped sacs of rat jejunum in which the outer muscle layers had been removed were found to maintain substantial transport and electrical activities.2. Mucosal and serosal membrane potentials of epithelial cells of normal and stripped everted sacs of rat jejunum were recorded in vitro together with the transmural potential difference.3. The cell interior was negative relative to both serosal and mucosal fluids, the transmural potential being the sum of the two membrane potentials.4. Changes in the transmural potentials in the presence of actively transferred hexoses and amino acids were entirely due to variations in the serosal potential, the mucosal potential being unchanged.5. Serosal and transmural potential increases on the addition of galactose were consistent with Michaelis-Menten kinetics, giving apparent K(m) values of 14.9 and 14.1 mM respectively.6. Phlorrhizin, ouabain, 2,4-dinitrophenol and sodium fluoroacetate inhibited serosal potential changes in the presence of galactose.7. Osmotic potentials resulting from transmural osmotic gradients originated from the serosal layers of the tissue.8. The results are consistent with the concept of a serosally located, electrogenic sodium pump which is stimulated by actively transferred hexoses and amino acids. The sodium-dependent entry mechanism at the mucosal membrane is non-electrogenic.