Sulphogalactolipid sulphohydrolase activity of arylsulphatase purified from a marine gastropod Charonia lampas.

Sulphatide, cerebroside 3-sulphate was hydrolyzed at a considerable rate by arylsulphatase (aryl-sulphate sulphohydrolase, EC 3.1.6.1) purified from a marine gastropod, Charonia lampas. However, it was scarcely hydrolyzed by glycosulphatase (sugar-sulphate sulphohydrolase, EC 3.1.6.3) from the same origin. The same was observed with seminolipid, a sulphoglycerogalactolipid. The enzymatic characteristics of both sulphogalactolipid and sulphohydrolase activities of the arylsulphatase were determined as follows. The enzyme activities are stimulated by the addition of sodium taurodeoxycholate and MnCl2. The pH optimum of sulphatide sulphohydrolase activity was pH 5.0, while seminolipid sulphohydrolase activity had maximum activity at pH 5.5. Both of these pH versus activity curves were broad. The Km value was 6.22-10-5 M for both substrates. However, the V values were sulphatide were lower by a factor of one-third than those with seminolipid. These enzyme activities were inhibited by substrates of the arysulphatase, i.e., p-nitrophenyl sulphate, p-nitrocatechol sulphate, ascorbate 2-sulphate and each other sulphogalactolipid, but not by glucose 6-sulphate. Sulphate and phosphate anions inhibited both of the enzyme activities.


Purification and properties of a beta-mannanase from alfalfa seeds.

A beta-mannanase (EC 3.2.1.25) has been purified from germinating Alfalfa seeds by successive chromatography steps; on hydroxyapatite, DEAE-cellulose and ECTEOLA-cellulose. The enzyme preparations were homogeneous as judged by gel electrophoresis. A 5000-fold increase in specific activity (from the crude extract) was obtained. The purified enzyme has a molecular weight of 40 000. Several of its properties were determined: pH optimum 5.2 and optimal temperature of activity 50 degrees C. The hydrolysis of galacto- and gluco-mannans (with various ratio of mannose to galactose and glucose) as well as that of mannooligosaccharides was studied in detail. A prefered point of attack at the third position from the non-reducing end was shown. Comparative results from the hydrolysis of intact galactomannans, of galactomannans previously hydrolysed by galactosidase, suggest that galactose hinders the accessibility of the mannan backbone to the enzyme.


Aminopeptidase II from Bacillus stearothermophilus.

1. The low molecular weight aminopeptidase (aminopeptidase II) from Bacillus stearothermophilus cells grown at 50 degrees C was purified to a homogeneous state. 2. Molecular weight determination by sodium dodecyl sulfate gel electrophoresis resulted in a value of 46 000 for the subunits. A molecular weight of 80 000-100 000 has been reported for the native enzyme. We therefore conclude that aminopeptidase II is a dimeric enzyme. 3. The amino-terminal sequence, the amino acid analysis and the subunit molecular weight of aminopeptidase II show no relationship to the corresponding data of aminopeptidase I. 4. Aminopeptidase II binds two Co2+ per subunit. The dissociation constants of these ions determined by binding studies and by kinetic analysis agree within experimental error.


Relative efficiencies of a soluble and immobilized two-enzyme system of glucose oxidase and catalase.

Dual catalysts of varying glucose oxidase (EC 1.1.3.4) and catalase (EC 1.11.1.6) activities were constructed by immobilization of the enzymes to silanized nickel silica alumina with glutaraldehyde. The amount of product formed and the efficiency of the systems were determined using either of the enzymes to initiate the cyclic reaction. The former depends on the activity of both enzymes in the system while efficiency describes how well the second enzyme in the sequence utilizes the intermediate of the reaction. Efficiency was a function both of the ratio of the two activities and their absolute values. An increase in the activity of the second enzyme of the reaction sequence of a decrease in the activity of the first enzyme increased the efficiency. A higher efficiency was observed with higher absolute activities of the enzymes when the ratios of the enzyme increased the efficiency. A higher efficiency was observed with higher absolute activities of the enzymes when the ratio of the enzymes was constant. Dual catalysts were compared to mixed catalysts (each enzyme immobilized to separate particles) and to soluble, homogeneous systems at equal total activities. In general, the dual catalysts were superior to either of the others. Computer simulations of the reaction rates indicated that all experiments were performed in the lag period of the two-step reaction.


Purification and properties of L-asparaginase B from Acinetobacter calcoaceticus.

L-Asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1) B from Acinetobacter calcoaceticus has been purified by precipitation with streptomycin, chromatography on DEAE-cellulose and CM-cellulose, gel filtration on Agarose and chromatography on phosphocellulose. The molecular weight of the enzyme was found to be 130 000. The enzyme was rather insensitive to pH changes between 7 and 9. The Michaelis constant was 3-10(-3) M. Hg2+, Cu2+, and Ni2+ as well as high ionic strength inhibited the activity of the enzyme, whereas citrate seemed to stimulate the activity. The enzyme catalyzed the deamination of L-glutamine to about the same extent as L-asparagine. The temperature stability of the enzyme is also reported. The enzyme had a weak tumor inhibitory power.


On the structure of the cofactor in the complex formed with thymidylate synthetase, 5,10-methylenetetrahy-drofolate and 5-fluoro-2'-deoxyuridylate.

A study was undertaken to ascertain whether dihydrofolic acid is produced in the complex formed with 5,10-methylenetetrahydrofolate, 5-fluorodeoxyuridylate and thymidylate synthetase, as suggested by ultraviolet difference spectral studies. The complex was formed using the cofactor specifically labeled with tritium at the 6-position. After dissociation by equilibration with unlabeled cofactor, it was demonstrated that the tritium remained exclusively at the 6-position. Had oxidation of the cofactor occurred within the complex to give a methylated enzyme form, tritium should have been transferred to the one-carbon unit of the cofactor. It was also found that the difference spectrum of the ternary complex which resembles that of dihydrofolic acid can also be produced by substituting an analog of the cofactor which is not susceptible to oxidation. The results described here demonstrate that oxidation of the cofactor does not occur in the ternary complex and suggest that the unusual ultraviolet spectrum results from perturbations of a chromophore of the bound cofactor.


Metabolic regulation of beta-glucosidase in the gut content of the snail Achatina achatina.

An energy-dependent polymerization-depolymerization phenomenon in the beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) in the gut contents of the giant African snail Achatina achatina has been observed. The formation of the octamer, tetramer and dimer from the monomer (mol. wt. approx. 41 000) and vice versa are catalysed by proteins in the present gut contents.


[Tryptic hydrolysis extended to the level of aspartyl bonds].

A quantitative modification of free carboxyl groups in peptides and proteins can be obtained, under mild conditions, by reacting them with ethylenediamine in the presence of N-ethyl-N'-(3-dimethylaminopropyl)-Carbodimide. Aminoethylasparagine and aminoethylglutamine side chains are thus generated in place of the corresponding carboxylic ones. The first kind of residue because of its structure closer to that of lysine, is a point of greater potential trypsic cleavage than the second one. The specificity and yields of this enzymatic cleavage reaction and its possible application in sequence studies are discussed.


Nucleic acids-protein interactions. Conformational changes induced by the binding of aromatic amines to polyadenylic acid.

The binding of Tryptamine, Serotonine, Phenylethylamine and Histamine to poly(A) in its single stranded form at pH 7 leads to a decrease of its circular dichroism (C.D) amplitude without any appreciable alteration of the shape of the C.D. spectrum. The magnitude of the effect depends on the size of the aromatic ring and decreases in the order : tryptamine greater than tyramine greater than phenylethylamine greather than histamine. A method is described which allows the calculation of association constants from C.D. data. The C.D. amplitude decreases linearly with concentration of bound molecules. Binding of aromatic amines to poly(A) leads to a change in the proton chemical shifts of both the amine and the poly(A) protons. Quantitative analysis of P.M.R. data demonstrates that the shifts of poly(A) protons are linearly related to the concentration of bound molecules.


[Study by fast kinetics of certain ligand combination and dissociation reactions with bis(maleimidomethyl)ether-hemoglobin (HbBME)].

Bis(N-maleimidomethyl)ether-hemoglobin (HbBME) is a well known derivative of hemoglobin obtained by reaction with bis(N-maleimidomethyl)ether, which forms an intra-chain bond in each of the beta subunit of the protein. Previous cristallographic determinations suggest that this chemical modification exerts an effect on the structure of the COOH-terminal region in the beta chain. As a consequence, the quaternary structure of deoxygenated HbBME is strongly destabilized in favor of the oxy conformation. Kinetic studies including oxygen dissociation and carbon monoxide binding reactions have been performed on HbBME in order to correlate these changes in structure with the reactivity of hemes in the protein. The disappearance of heme-heme interaction in HbBME is expressed in the character of the oxygen dissociation kinetics. With respect of this reaction, we show that the reactivity of alpha chains remains unchanged inside the chemically modified tetramer, whilst that of beta chains is increased. Carbon monoxide binding kinetics show heterogeneity with two well separated phases. The fast phase contributes about 75 per cent of the total absorbance change and has a rate of binding similar to that of fastly reacting hemoglobins. The slow phase show the same rate as in native deoxyhemoglobin. The effects of inositolhexaphospate on the these kinetics have been studied. They consist mainly in the decrease of fast phase which can disappear completely according to the experimental conditions. These experiments suggest that deoxy-HbBME exists in solution as a mixture of two isomers in slow equilibrium. Taking account of previous structural studies, these results are discussed in comparison with an hemoglobin mutant with very similar properties, hemoglobin Bethesda (Tyr 145beta leads to His). The importance of the COOH-terminal region on the functional properties of hemoglobin is once again emphasized.


The parameters of the binding of estradiol and progesterone to their antibodies in presence of rat plasma.

The binding of estradiol and progesterone to the corresponding antibodies has been studied in system containing : a) antibody and hormone or b) antibody, hormone and rat plasma. In sytem a) the apparent association constant and the concentration of the antibody have been determined and the optimal conditions of a standard antibody-assay have been elaborated. In system b) the specific binding of hormone to antibody in presence of rat plasma has been measured, and the value of the "Operational Association Constant", Kop, has been calculated. Kop has the dimensions of an apparent association constant : it defines the ratio hormone bound/unbound to antibody, as a function of hormone concentration in system b). Based upon these experiments, the extent of hormone-binding to antibody injected to rats can be predicted. When antibody and hormone concentrations are measured in the plasma, the concentrations of hormone bound to antibody can be calculated.


[Multiplicity of the molecular forms of acetylcholinesterase and thermal acclimatization in Carassius auratus].

Multiple forms of acetylcholinesterase have been studied in Goldfish adapted to 15 degrees C and 25 degrees C. Three forms of enzyme (sedimenting at 18S, 12S and 5S) could be distinguished by sucrose gradient centrifugation. Their molecular and enzymatic properties did not vary with environmental temperature. It was noted that the relative proportion of the three forms differed between brain and muscle extracts, the 18S forms predominating in muscle (about 75 per cent) the 12S forms being more abundant in  the brain, suggesting a physiological differentiation between these forms. The latter form varied from 48 per cent to 70 per cent in Goldfish adapted to 15 degrees and 25 degrees C respectively. The relative efficiency of saline buffer solubilization for each form also depended on the tissue used and in all cases decreased with rising environmental temperature. These two facts are taken to reflect interactions between acetylcholinesterase and membrane that depend on the nature of the membrane and probably involve the aliphatic chains of its phospholipids. The greater case of solubilization found in the low temperature adapted fish may be a function of the increased fluidity of the cellular membranes formed at lower temperatures.


Changes in the sedimentation properties of acetycholinesterase during neuroblastoma differentiation.

The adrenergic mouse neuroblastoma clone NIE 115 contains two species of AChE which sediment at 4S and 11S. These two species are found both in logarithmic growing phase cells (round neuroblast morphology) and in cells which have undergone morphological differentiation due to the elimination of serum. The 4S form is predominant in the growing cells (70 per cent) whereas the 11S form is more abundant (55 per cent to 65 per cent) in the cells with neurites. When protein synthesis is inhibited by cycloheximide, there is an increase states : we postulate that the 11S species is formed by a conversion of the 4S species. When cell division is blocked by sodium butyrate, there is an increase in AChE activity but no modification in the proportion of 4S/11S species as compared to the cells in growing phase. We were unable to associate temporally the increase in the 11S species with neurite outgrowth ; when cells were allowed to retract their neurites and were subsequently maintained in a GROWING state for 10 to 15 days, the 11s species still predominates. Although the presence of the 11S molecule cannot always be correlated with the state of morphological differentiation, the shift in sedimentation coefficient of AChE form 4S to 11S might eventually constitute a reference in the study of biochemical events leading to terminal differentiation in this system.


[Fractionation of ciguatoxic lipid extracts in alkaline medium].

A modification of the extraction procedure for obtaining ciguatoxic substances from the tissues of various poisonous reef fish has been developed. Rapid alkali treatment of the residue obtained at an early stage is efficient in separating the ciguatoxic fraction from toxic impurities which interfere with pharmacological tests. It is thus possibles to carry out a more precise dosage of the material separated in this way. Alkali treatment does not affect either the physiological activity in cats and mice of the ciguatoxic substances nor their behaviour in a preparative thin layer chromatography in a benzene-butanol system.


Amplitude of pupillary contraction as a function of intensity of illumination in schizophrenia.

When the amplitude of pupillary contraction of normal, healthy adults was binocularly recorded as a function of increasing intensity of light-stimulation, a linear relationship was found between the amplitude and log intensity. Schizophrenic patients deviated significantly from this systematic response pattern in two ways. One group of patients (35%) manifested the same pupillomotor threshold as the normals, however, as the intensity of light was systematically increased mean amplitude and rate of pupillary contraction fell below that evidenced by normals. Another group of patients (65%) were distinguished by an abnormal pupillomotor threshold, specifically requiring an increase of one log intensity unit for the elicitation of a recordable pupillary contraction. Moreover, as the light intensity increased, the mean amplitude of contraction was significantly attenuated at all intensities below that of the normals and of the schizophrenics who manifested a normal pupillomotor threshold. In addition, it was found that the average diameter of the dark-adapted pupil was smaller in both groups of patients as compared to the healthy adults, although there was no difference between the patient groups on the variable. As pupillary reactivity to stress in normals is characterized by an increase in the diameter of the dark-adapted pupil representing increased sympathetic outflow and by a reciprocal increase in the diameter of the light-adapted pupil representing increased supranuclear inhibition, the results of the study do not support the assertion that schizophrenics are hyperaroused. It is suggested schizophrenia may be considered a tonic autonomic dysfunctional state of mock-arousal characterized by either abnormally high levels of central supranuclear inhibition or by defective sympathetic outflow, or both.


Regional serotonin levels in brain: a comparison of depressive suicides and alcoholic suicides with controls.

The levels of 5-hydroxytryptamine have been measured in 33 areas of the human brain and these levels compared in depressed suicides, in alcoholic suicides, and in controls. The values obtained for control brains ranged from 5.3 mumole 5-HT/kg wet weight in substantia nigra to 0.4 mumole 5-HT/kg wet weight in frontal gray. No significant differences were found among diagnostic groups in any of the areas studied.


Current density in bilateral and unilateral ECT.

This paper describes a method of computer simulation which will enable the researcher to test, on the theoretical level, the effects of a wide variety of electrode placements, currents, tissue resistivities, and volumetric differences on the distribution of current within the brain. It is based on a nonhomogenous, threesphere model of the head and is capable of expansion to account for known inhomogenities within the brain. It should prove a useful research tool for a wide variety of purposes.


Bipolar manic-depressives and unipolar depressives distinguished by tests of lateral asymmetry.

Tests of lateral asymmetry in hand preference and superiority in thumb opposition rotation (opposing the thumb's pulp surface to that of the little finger) have been applied to bipolar and unipolar affective patients in an attempt to evaluate the effectiveness of these tests in differentiating the bipolar and unipolar patient populations. Two comparison samples were also tested: nonpsychotic central nervous system (CNS) disease patients, and normal controls. The normals divided almost evenly into pure dominance (e.g., right-handed, and superior right thumb opposition) and cross-dominance (e.g., right-handed, but superior left thumb opposition). All but one of the CNS disease patients were cross-dominant; the bipolars were predominantly pure dominant; while the unipolars, in contrast to the pure dominant bipolars, were in the majority cross-dominant. This result is consistent with the view that there are two types of affective disorder, bipolar manic-depressive and unipolar depressive illness.


Criterion level and instructional effects in the voluntary control of heart rate.

Two experiments are reported. In experiment 1 the effects of different punishment criteria on the acquisition of voluntary control of heart rate was studied in three groups of 10 subjects. Punishment criterion was manipulated so that the 10, 30 and 50% most extreme interbeat intervals in the opposite direction from the desired heart rate change were punished. Subjects received four training sessions, two directed at increasing heart rate, and two at decreasing. Substantial bidirectional heart rate changes were obtained very early in training. Some weak evidence of criterion effects was obtained. In a supplementary experiment modelled on experiment 1, the instructions plus feedback used in experiment 1 were compared with instructions alone. Feedback did not aid heart rate control. In both experiments there was evidence of skeletal involvement in the heart rate change.


Dishabituation of the electrodermal orienting response following decay of sensitization.

This study tested one of the basic propositions of dual-process theory (Groves and Thompson, 1970) that 'dishabituation' results from an independent, superimposed process of excitation and not from disruption of the habituation process as proposed by Sokolov (1963). Skin conductance level (SCL) was employed as a measure of sensitization. On the basis of dual-process theory, it was hypothesized that if sensitization produced by the 'dishabituating' stimulus has decayed prior to re-presentation of the habituating stimulus, skin conductance response (SCR) amplitude to the habituating stimulus will not differ from that displayed by a control group which did not receive presentation of the 'dishabituating' stimulus. In experiment 1 (N = 10), subjects received 13 presentations of a 1000 Hz, 70 dB tone of 3 sec duration with interstimulus intervals of 40, 50 and 60 sec. Between trials 11 and 12, there was one presentation of a dishabituating (light) stimulus. Analysis of SCL indicated that an interval of 50 sec between trials 12 and 13 was sufficient to allow sensitization to decline to the pre-light level. The experimental conditions in experiment 2 (N = 32) were the same as in experiment 1 except that only half the subjects received presentation of the dishabituating stimulus. The results indicated that although there were no group differences in SCR amplitude on trials 1-11, experimental subjects displayed significantly larger responses on trial 13 than did control subjects. These results suggest that interpolation of a different stimulus in an habituation series does, in fact, disrupt the habituation process.


Effects of stimulus information and stimulus duration on amplitude and habituation of the electrodermal orienting response.

This study was designed to investigate the effects of stimulus information and stimulus duration on the skin conductance response (SCR) component of the orienting response (OR). Three levels of stimulus information were combined with two levels of stimulus duration in a 3 X 2 independent groups factorial design (N = 90). On the basis of Sokolov's (1966) theory, it was hypothesized that: (a) high information stimuli would elicit larger initial SCR'S than would stimuli of low information, (B) high-information stimuli would evoke more SCRs throughout a habituation series than would low-information stimuli, and (c) high-information stimuli would require more presentations to reach a habituation criterion than would stimuli of low information. It was also hypothesized that (d) long-duration stimuli would require fewer presentations to reach a habituation criterion and result in a faster rate of habituation than would stimuli of short duration. The stimuli consisted of black and white chequered patterns containing 12, 26 or 60 bits of information. Stimulus duration was either 0.5 or 4.5 sec, and each subject received 20 presentations at randomly ordered intervals of 20, 25, 30 and 35 sec. The results provided support for hypotheses (b), (c) and (d), but not for hypothesis (a). These results support the view that OR habituation can be conceptualized as a process of information extraction.


Relationship between SCR, heart rate and information processing.

This study was designed to investigate the relationship between the amount of information processing in concept learning (CL) and autonomic physiological activity as measured by skin conductance response (SCR). Heart rate (HR) was also measured. Two conceptual rules were used: a conjunctive and an inclusive disjunctive concept. The results indicated that the SCR rose with increasing amount of information processing at the feedback during CL. Furthermore, it was shown that SCR increased with increasing difficulty of the conceptual rule. HR appeared not to vary with amount of information processing, nor with type of concept. In the conjunctive series, however, there was a significant difference between HR at stimulus presentation and HR at feedback.


Psychophysical judgment: electro-cortical and heart rate correlates of accuracy and uncertainty.

The relationship between perceptual accuracy and physiological response amplitude was investigated in an auditory pitch discrimination experiment. Confidence ratings were obtained from all subjects following each trial. The stimulus set consisted of three tones of different frequencies spaced in a manner to provide both easy and difficult discriminations. Heart rate, EEG and vertical eye movement were recorded throughout the experiment. The results of the experiment indicated that the largest evoked cardiac rate response was elicited by the stimulus which produced the fewest errors in judgment; larger auditory evoked potentials, particularly the late positive component (P300), were associated with the 'easy' stimulus; greater cortical negativity was associated with the difficult stimuli. Eye activity was found to covary with judgmental accuracy; cortical slow wave activity was particularly sensitive to the confidence, or 'uncertainty' parameter. A 'decision tree' model was hypothesized to describe the processing mechanism involved in solving the discrimination problem.


Attention effects on auditory evoked potentials to infrequent events.

In two experiments, evoked potentials (EPs) were obtained for three levels of attention, defined by instructions to press a button to, listen to or ignore an infrequent event. In experiment 1, a regular train of standard tone pips was occasionally and randomly interrupted by a tone of different pitch (pitch change) or by the omission of a tone (gap). At the vertex (Cz) a late positive peak (P3) to the infrequent event became larger and later with increased attention, while the earlier negative peak (N1) became later but not larger. In experiment 2, EPs to pitch changes were recorded from Cz, frontal (Fz) and parietal (Pz) locations. All effects obtained in experiment 1 were replicated. The distribution of P3 was different during the different attention conditions.


Advances in percutaneous electrode systems.

In the past eight years, developing a percutaneous electrode system has advanced to a successful, yet simple, method to transmit electrical signals, overcoming the serious problems of excessive mechanical irritation at the skin interface. Experience with over 50-74% in the clinical applications of 1) chronic pain relief; 2) contracture correction; and 3) sensory feedback.


The mechanical behavior of LTI carbon dental implants.

LTI pyrolytic carbon blade-type dental implants consisting of a graphite substrate and an LTI pyrolytic carbon coating have a strength that increases with the coating thickness. For implants having a coating thickness of about 0.03 in., average fracture loads of about 1500 lb and 230 lb were obtained in axial compressive loading and eccentric loading (e.g., axial compressive loading plus a bending moment), respectively. Depending on the type of loading, the maximum stresses in the graphite substrate were calculated to be very close to its compressive or tensile fracture strength. Also studied was the effect of a variety of defects on the overall strength of the implants.


Dental amalgam stabilization by selective interfacial amalgamation.

The purpose of this investigation was to explore the feasibility of enhancing the electrochemical stability of dental amalgam restorations by a process of "selective interfacial amalgamation." If dental amalgam restorations can be selectively alloyed at the tooth-amalgam interface, to a minor thickness as compared with the dimensions of the bulk amalgam, so as to present a more electrochemically stable phase than psi2 to the oral environment, corrosion will be reduced and desirable qualities of existing amalgams can be utilized. It was found that selective interfacial amalgamation was indeed possible and that it could be readily accomplished using a silver suspension as a cavity liner. By then placing a conventional silver-tin amalgam according to ordinary dental techniques, mercury expressed during hand condensing reacted with the silver in the liner resulting in the formation of an integral amalgam restoration with the more noble psi1 phase adjacent to tooth structure. In vitro corrosion tests of samples so prepared exhibited corrosion resistance far superior to unlined control samples.


Blood compatibility of silicone rubber chemically coated with cross-linked albumin.

A new method is reported for chemically coating cross-linked albumin onto silicone rubber in an attempt to improve the blood compatibility of the material. Promising results were obtained in an evaluation using both vena cava and renal embolus antithrombogenicity tests ondogs. Coated silicone rubber rings induced much less renal emboli than uncoated ones after one week implantation.


Effect of electrical stimulation on the interfacial tensile strength and amount of bone formation.

The effect of electrical stimulation upon the direct tensile strength of the interface union between porous calcium aluminate implants and bone plus the amount of bone formation were investigated in the femurs of rabbits. The study indicates there is an increased tensile strength of the interface in proportion to the amount of bone formation into the pores and the amount of electrical stimulation used "in vivo."


Characterization of drug iontophoresis with a fast microassay technique.

The iontophoretic release of drugs from micropipettes into free (Ringer's) solution was described using an ion-selective microelectrode assay method. This characterization, with a temporal resolution of 20 ms, showed that the equilibrium rate of drug transport was not linearly proportional to release current; the departure from linearity was increased by backing current and the result was demonstrated with analytically derived drug release functions. The general relation between the drug transport rate and release current was independent of the specific drug or pipette resistance; no functional relation was observed that might quantitatively predict this dependence without prior use of the assay. The diffusion coefficients at 25 degrees C in frog Ringer's of the drugs used in this study, all neuromuscular agonists, were determined: all values X 10(6) cm2/s; acetylcholine 6.11 +/- 0.30; carbamylcholine 7.44 +/- 0.34; 3-(m-hydroxyphenyl) prophyltrimethyl ammonium 5.79 +/- 0.13.


Analysis of discharges recorded simultaneously from pairs of auditory nerve fibers.

Spike trains were recorded simultaneously from pairs of auditory nerve fibres in anesthetized cats. Tests for correlation between spike trains were developed for spontaneous activity and for discharge patterns resulting from single-tone stimuli. The application of these tests to the recordings indicates that the responses of auditory nerve fibers to a tone and to silence can be described as statistically independent point processes. This result implies that the initiation of spikes in these fibers is governed by localized processes specific for each fiber.


Digital simulation of associated and nonassociated liquid membrane electrochemical properties.

The method and results of a digital simulation of electrochemical properties for associated and nonassociated liquid ion-exchange membranes are presented. It is assumed that the membranes is ideally permselective, sites are completely trapped, electroneutrality holds everywhere in the membrane, and the bathing solutions contain no more than two counterions, of which one is completely dissociated in the membrane. Electrochemical properties are simulated for the single counterion case and in the interference region. Concentration profiles, potentiometric responses, transient potential responses to activity steps, and current-voltage curves are given and the effects of ion-pairing and species mobilities are studied. It is found that ion-pairing increases the potentiometric selectivity toward the complexing ion over the noncomplexing ion. Transient responses to an ion activity step are shown to depend in a complex way on the ion-pair formation constant and the various mobilities. Current-voltage curves are simulated for varying degrees of ion-pairing and qualitative agreement is found with previous theoretical treatments, as well as quantitative agreement in those cases where closed-form expressions are known.


Slow sodium inactivation in Myxicola axons. Evidence for a second inactive state.

Sodium inactivation and reactivation have been examined in voltage-clamped Myxicola axons after long-lasting membrane depolarizations produced either directly by changes in holding potential or indirectly by elevation of external K+ concentration. The results suggest the existence of a second inactivated state of the sodium channel with associated voltage-dependent rate constants at least two orders of magnitude lower than those of the fast inactivation process commonly examined. No specific influence of external [K+] on slow Na+ inactivation could be detected.


Model for the chemotactic response of a bacterial population.

We present a mathematical model for the motion of a bacterial population in prescribed attractant or repellent gradients. The model is suggested by the observations of Mesibov et al. (1973, J. Gen. Physiol. 62:203) and Brown and Berg (1974, Proc. Natl. Acad. Sci. U.S.A. 71:1388) who found that the sensitivity of the chemotactic response depends on the concentration of attractant. Predictions of the theory are in general agreement with the experiments of Dahlquist et al. (1972, Nat. New Biol. 236:120) and of Mesibov et al. on populations of motile bacteria in fixed attractant gradients. Additional tests of the model are proposed.


Radiation damage in tripalmitin layers studied by means of infrared spectroscopy and electron microscopy.

Structural deteriorations in biomembranes, as inevitably induced while structural information is gathered by electron optical methods, were evaluated by infrared spectroscopy. Tripalmitin model membranes were irradiated with 100 keV-electrons in an electron microscope. The intensity decay of group vibrations over the dose reveals the sequence of damage in the polar and nonpolar part of the molecule. The C-C backbone, being the most important structural feature, shows a significant latency effect up to 0.6 e-/A2 and is completely disordered by 3 e-/A2, corresponding to about three inelastic processes per molecule.


Physical characteristics of mouse sperm nuclei.

The nuclei of epididymal sperm, isolated from C57BL/6J and CBA/J inbred mice by their resistance to trypsin digestion, retain the shape differences of the intact sperm head. Various physical characteristics of these nuclei were measured and compared. The measurement of the projected dimensions of nuclei showed that the CBA nuclei are 13.5% longer than C57BL/6 nuclei (8.64 +/- 0.02 mum compared with 7.61 +/- 0.02 mum), 0.8% narrower (3.51 +/- 0.01 vs. 3.54 +/-0.01 mum) with 6.8% more area (22.34 +/- 0.10 vs. 20.91 +/- 0.09 mum2). However, the volumes of the nuclei as based on reconstructing calibrated electronmicrographs of serial sections of the nuclei indicated that CBA are about 7% smaller than C57BL/6 nuclei (3.72 +/- 0.08 vs. 4.01 +/- 0.03 mum3). The buoyant density of the CBA nuclei is 1.435 +/- 0.002 g/cm3 compared with 1.433 +/- 0.002 g/cm3 for the C57BL/6 nuclei as determined on linear CsCl and Renografin-76 density gradients and confirmed by a technique utilizing physiological tonicities. Therefore, the average mass of the CBA nuclei is less than that of the C57BL/6 nuclei (5.34 +/- 0.12 vs. 5.75 +/- 0.05 pg). The sedimentation velocities at unit gravity of nuclei from 11 inbred strains differ over a range of more than 6% with CBA nuclei sedimenting about 2.0% more slowly than C57BL/6 nuclei. We show that for these nuclei the sedimentation velocity can be related to their buoyant density, volume and a sedimentation shape factor. Within the errors of our measurements of these various characteristics, it was found that C57BL/6 and CBA nuclei have similar sedimentation shape factors. Therefore, the difference in sedimentation velocity between these nuclei appears to be primarily a result of differences in volume. The possible applications of these techniques to the physical separation of sperm are evaluated in the discussion.


A new analysis for membrane noise. The integral spectrum.

A new method of random data analysis has been developed with special implications for membrane noise. The integral spectrometer uses overlapping broad-band filters of simple design, whose bandwidth increases linearly with center frequency. A random two-state process, which has a Lorentzian-shaped spectral density, results in an integral spectrum whose maximum value occurs at the mean frequency of the events, and which is symmetric about that frequency on a semilog plot. 1/f noise is flat and does not distort the symmetry on the frequency axis. The integral spectrum exchanges resolution on the frequency axis for accuracy in the amplitude. The expected statistical error in amplitude has been calculated for three types of membrane noise assuming finite data. The integral spectrum compares favorably with conventional spectral densities and may be a reasonable alternative for random data analysis.


On the primary quantum yields in the bacteriorhodopsin photocycle.

Pulsed Nd laser experiments in suspensions of the purple membrane of Halobacterium halobium are carried out at room temperature. At sufficiently high laser intensities, a photostationary mixture of bacteriorhodopsin (BR) and its red-shifted (batho) photoproduct (K) is obtained. The spectra of the first three intermediates in the photocycle are reported. The data yield a value of phi1/phi2=0.40 +/- 0.05 for the ratio of the quantum yields of the forward (phi1) and reverse (phi2) processes, setting an upper limit of approximately 0.4 for the quantum efficiency of the cycle at room temperature. This method is generally available for the determination of phi2 in the case of a photoequilibrium: A in equilibrium B, where B is a short-lived transient and phi1 is known from low intensity measurements. Its potential application is of importance for the study of the photophysics of visual pigments at physiological temperatures.


Photoconductivity in bone and tendon.

Ultraviolet light can be used to stimulate electrical current flow in bone and tendon. This stimulated photocurrent is directional. In tendon the photocurrent parallel to the fibrils is greater than the photocurrent perpendicular to the fibrils. In bone, the longitudinal photocurrent is less than the transverse photocurrent.


Inhibition of DNA replication by ultraviolet light.

DNA replication in ultraviolet-irradiated HeLa cells was studied by two different techniques: measurements of the kinetics of semiconservative DNA synthesis, and DNA fiber autoradiography. In examining the kinetics of semiconservative DNA synthesis, density label was used to avoid measuring the incorporation due to repair replication. The extent of inhibition varied with time. After doses of less than 10J/m2 the rate was initially depressed but later showed some recovery. After higher doses, a constant, low rate of synthesis was seen for at least the initial 6 h. An analysis of these data indicated that the inhibition of DNA synthesis could be explained by replication forks halting at pyrimidine dimers. DNA fiber autoradiography was used to further characterize replication after ultraviolet irradiation. The average length of labeled segments in irradiated cells increased in the time immediately after irradiation, and then leveled off. This is the predicted pattern if DNA synthesis in each replicon continued at its previous rate until a lesion is reached, and then halted. The frequency of lesions that block synthesis is approximately the same as the frequency of pyrimidine dimers.


Red blood cell shapes as explained on the basis of curvature elasticity.

Assuming that the shape of red blood cells is controlled by the curvature elasticity of the surrounding membrane, we fit theoretical shapes to the contours Evans and co-workers determined by interference microscopy. Very good agreement is obtained for disc shapes. The fit is not so good for less common shapes, which may result from Evans' parametric representation and from the interference of shear elasticity.


A model for the stimulation of taste receptor cells by salt.

A taste cell mucosal surface is regarded as a planar region containing bound anionic sites and openings to ionic channels. It is assumed that the bulk aqueous properties of the exterior phase are not continuous with the surface but terminate at a plane near the surface. The region between the (Stern) plane and the membrane is regarded as having a lower dielectric constant than bulk water. This fact admits the possibility of ion pair formation between fixed sites and mobile cations. Mobile ion pairs entering the region may also bind to a fixed anionic site. Thus, it is assumed that mobile cations and ion pairs are potential determining species at the surface. Binding cations neutralizes surface charges, whereas binding mobile ion pairs does not. This competition accounts for the observed anion effect on stimulation of tast receptors by sodium salts. The potential profile is constructed by superimposing the phase boundary potentials with an ionic diffusion potential across the membrane. The model accounts for the anion effect on receptor potential, pH effects, the reversal of polarity when cells are treated with FeCl3, and the so-called "water reponse," depolarization of the taste cell upon dilution of the stimulant solution below a critical lower limit. The proposed model does not require both bound cationic and anionic receptors, and further suggests that limited access to a Stern-like region continuous with membrane channels may generally serve to control transport of ions.


Rate of DNA chain elongation in ultraviolet light-irradiated mammalian cells as estimated by a bromodeoxyuridine photolysis method.

Using a new method, we show that, when the DNA chain elongation rate is measured for short time periods, ultraviolet light does not decrease this rate. The method is based on the photolysis of bromouracil-containing DNA by 313 nm light and alkaline sucrose gradients.


A comment on Martin's relation.

In the limit of slowly varying synaptic conductance changes, a quantity proportional to the quantal content of a synaptic potential is provided by Martin's formula: 1/(VO/Vp-1), where Vp is the peak amplitude of the synaptic potential and Vo is the synaptic equilibrium potential. If the synaptic conductance change is not slowly varying on the time scale of the postsynaptic cell's membrane time constant, Martin's formula overestimates the effects of nonlinear summation and provides an upper limit for the actual quantal content. In the limit of rapidly varying synaptic conductance changes the quantity ln(1/[1-Vp/Vo]) is proportional to the quantal content. This formula underestimates the effects of nonlinear summation and gives a lower limit for the quantal content for cases in which the synaptic conductance is not rapidly varying. These two formulas used together provide upper and lower bounds to the correction for nonlinear summation of postsynaptic potentials.


Piezoelectric and related properties of hydrated collagen.

Two piezoelectric constants (polarization per unit stress, d=d'-id'', and polarization per unit strain, e=e'-ie''), the elastic constant, and dielectric constant are determined for oriented collagen at different hydration levels at 10 Hz from -150 to 50 degrees C. With no hydration (approximately 0% H2O), d' increases slightly with higher temperatures, while e' decreases slightly. Near 11 wt% H2O, both d' and e' increase then decrease around 0 degrees C, and is probably caused by an increase of the dielectric constant and the ionic conductivity in the nonpiezoelectric phase. Hydration greater than 25 wt%, d' and e' decrease above -50 degrees C which is considered to be due to a greater ionic conductivity surrounding the piezoelectric phase.


Numerical inversion of the Perrin equations for rotational and translational diffusion constants by iterative techniques.

An iterative numerical technique is presented which allows the semiaxes for prolate and oblate ellipsoids to be determined from the Perrin equations for rotational and translational diffusion constants. The use of this inversion technique is illustrated by application to the proteins: lysozyme, bovine serum albumin, human transferrin, and bovine rhodopsin solubilized in digitonin.


Electron transport in xanthine oxidase. A model for other biological electron transport chains.

Part of the catalytic function of xanthine oxidase (XO) involves the transfer of two electrons from a substrate to a molybdenum ion on the enzyme followed by equilibration of these electrons among other electron resting sites on the enzyme. The electrons are removed from the enzyme at a flavin by oxygen to form hydrogen peroxide. This paper considers mechanisms which allow the electrons to equilibrate between the different resting sites on the enzyme. The mechanisms are chosen to be consistent with known properties of the enzyme (relative reduction potentials, electron transfer rates, and the estimated separation of these resting sites). Tunneling appears to be a good candidate to account for most of the electron transport. It is shown that the XO electron transport system is similar in many respects to sections of mitochondrial electron transport chains and can serve as a nice model for parts of these more complicated biological electron transport systems.


Squid giant axons. A model for the neuron soma?

Insertion of electrically floating wires along the axis of a squid giant axon produces an apparent increase in diameter in the region where the wire surface has been treated to give it a low resistance. The shape of action potentials propagating into this region depend upon the surface resistance (and the length) of the wire. As this segment's internal resistance is lowered by reducing the wire's surface resistance, the following characteristic sequence of changes in the action potential is seen at the transition region: (a) the duration increases; (b) two peaks develop, the first one generated in the normal axon region and the second one generated later in the axial wire region, and; (c) blockage occurs (for a very low resistance wire). Action potentials recorded at the membrane region near the tip of the axial wire in (b) resemble those recorded at the initial segment of neurons upon antidromic invasions. Squid axon action potentials propagated from a normal region into that containing the low resistance wire also resemble antidromic invasions recorded in neuron somas. Hyperpolarizing current pulses applied through the wire act as if the wire surface resistance was momentarily reduced. For example, the two components of the action potential recorded at the axial wire membrane region noted in (b) can be sequentially blocked by the application of increasing hyperpolarizing current through the wire. Similar effects are seen when hyperpolarizing currents are injected into motoneuron somas. It is concluded that the geometrical properties of the junction of a neuron axon with its soma may be in themselves sufficient to determine the shape of the action potentials usually recorded by microelectrodes.


Differentiation of channel models by noise analysis.

Differentiation of membrane channel models based on fluctuation (or noise) analysis is discussed. The theory is particularly useful in distinguishing a single-conductance model (Hodgkin-Huxley formalism) from a multiconductance model. When applied to the frog node of Ranvier, it seems likely that the potassium channels of the membrane may have multiconductance states.


A possible two-photon effect in vitro using a focused laser beam.

A probable two-photon effect is described as a result of focusing an intense pulsed laser beam onto chromosomes of living cells. The effect was suggested after the derivation of a two-photon action spectrum and the demonstration of a lack of reciprocity.


Pulse wave transmission times in central aorta and peripheral arteries in normal children.

Pulse wave transmission times and pulse wave velocities in central aorta and peripheral arteries were measured in a group of 85 healthy children and adolescents between the ages of 1 and 21 years. A new external plethysmograph is described which gives reliable tracings of external pulsations. A method is given to calculate real pulse wave transmission time from the aortic valves to the groin.


Vascular contraction: effect of age and extracellular calcium.

Contractile responses to norepinephrine, serotonin and potassium chloride were determined in vitro for aortas from rats 1, 2, 3 and 12 months of age. Responses were measured under conditions of optimum length (3 cm) and resting tension (1 g). Aortic response to a maximum concentration of norepinephrine was greatest for vessels from 3-month-old rats. For all three agonists, aortas from 12-month-old rats contracted less than aortas from 2-month-old rats. The role of calcium in aortic contraction also varied with age. For rats 1-2 months of age, serotonin and potassium chloride-induced contractions were highly dependent on extracellular calcium, while norepinephrine-induced contraction showed only a slight dependence on extracellular calcium. In 12-month-old rats, all agonists were dependent on extracellular calcium for contraction. For serotonin and norepinephrine, the ability of muscle to contract in calcium-free media was decreased with age. Although the mechanism for such an altered dependence of aortic contraction on calcium has not been established, it is proposed that the utilization of extracellular calcium for contraction is not only agonist- but also age-dependent.


Intrinsic prostaglandin release. A mediator of anoxia-induced relaxation in an isolated coronary artery preparation.

Isolated coronary artery strips of the bovine heart in vitro relax in response to decreased bath oxygen tensions (from 515 mm Hg to 112, 53, and 38 mm Hg). In addition, the rate of intrinsic formation and release of prostaglandin is considerably increased under conditions of decreased PO2. The vascular relaxations under reduced PO2 are attenuated and the elevations in prostaglandin output blocked by prostaglandin synthesis inhibitors. It appears that alterations in the output of a PGE with vasodilator activity, probably E1, is a significant factor regulating the compensatory changes in tone of the coronary arteries in response to anoxic conditions.


Vasodilator effect of thrombins prepared from normal or deficient human or canine plasmas.

Thrombins prepared from plasmas deficient in various clotting factors are capable of inducing vasodilator response to the hindlimb of the dog and this response proved to be similar to that produced by thrombins prepared from normal plasmas. Thus the vascular effect of thrombin is not mediated by any other clotting factor which might be present in small amounts in the thrombin preparations. Thrombin prepared from canine normal plasma exerted a more potent vasodilator response, indicating a species specificity for the vascular response to thrombin. Since the vasodilating effect of thrombin is not mediated by (i) a nervous mechanism, (ii) any known vasodilating substance or (iii) any other clotting factor, it is concluded that the thrombin moiety possesses vasodilating properties.


Effect of hexachlorobenzene on some growth parameters of Chlorella pyrenoidosa.

Chlorella pyrenoidosa was incubated with HCB (0.001-10.0 ppm) in a "light-thermostat" at 30 degrees C for 46 h with continuous light (4000 Lux) and aeration. HCB decreased growth as deduced from measurements of chlorophyll content, dry matter, carbohydrate content, and total nitrogen. Incubation with HCB for three months in Erlenmeyer-flasks resulted in an increase of chlorophyll over control value in cultures receiving 0.1 and 1.0 ppm HCB. After transfer of the cultures from Erlenmeyer-flasks to growth conditions of a "light-thermostat", growth of the algae was greatly enhanced by all HCB concentrations studied; a concentration of 0.1 ppm being most effective.


The short-term toxicity of some feed additives to different freshwater organisms.

The short-term toxicity (EC50 respectively LC50 after 2 or 4 days) of 13 feed additives was determined to 4 freshwater organisms of different trophical levels: Chlorella pyrenoidosa, Daphnia magna, Lebistes reticulatus and Salmo gairdneri. The most toxic (LC(EC)50 less than 1 mg/1) were robenidine (to all tested organisms) and stenorol (to Daphnia); moderately toxic (1 less than LC(EC)50 less than 10 mg/1) was pyrimethamine. Amprolium, ethopabate, furazolidone and zoalene proved to be little toxic (LC(EC)50 greater than 10 mg/1); whereas buquinolate, carbadox, clopidol, decoquinate, grofas and sulfaquinoxaline were under the experimental conditions not toxic for the tested organisms.


Determination of lead in human lungs by direct flameless atomic absorption analysis of small tissue samples.

The direct-atomization technique of flameless atomic absorption spectroscopy has shown to be a useful and accurate method when applied to determination of the concentration of lead in human lung tissue. The analytical results are highly reproducible and agree with those obtained by the conventional flame atomic absorption technique.


Selected list of books and journals for a small dental library.

This subject list of 109 dental books and 20 dental journals is intended to help the dental book committee and the librarian of a small health sciences library achieve a balanced collection of dental books and journals. Cost of books totals $2,180.00, that of journals is $571,00, making a total of $2,751.00. Cost of starred books totals $927.30, that of starred journals is $109.50, making a total of $1,036.80.


New library buildings. Part VII. The Health Sciences Library of the University of Virginia.

This article describes the new Health Sciences Library at the University of Virginia Medical Center in Charlottesville, Virginia. The library was under construction for about two years and opened in August 1975. It comprises an area of 66,250 sq. ft. gross, almost 44,000 sq. ft. net, and provides space for approximately 190,000 volumes, 500 readers, and a staff of 35. The cost of construction was $2,350,000, plus approximately $400,000 for furnishings and equipment. A portion of the library is located on a bridge spanning a four-lane highway. Special features include a 6,000 net sq. ft. audiovisual information center, Elecompack (TM) motorized shelves for little-used materials, and a closed-circuit television surveillance system.


Evaluation of a clinical medical librarianship program at a university Health Sciences Library.

An evaluation of the clinical medical librarianship program at the University of Washington Health Sciences Library was undertaken to determine the benefits of the program to patient care and to the education of the recipients of the service. Results of a questionnaire reflected overwhelming acceptance  of the clinical medical librarianship program. Guidelines for the establishment of a limited clinical medical librarianship program are described. A statistical cost analysis of the program is included.


Effects of binding policy and other factors on the availability of journal issues.

Random samples of journal issues, derived from a test set of 106 biomedical journal titles, were checked against the shelves of the Woodward Biomedical Library under circulating and noncirculating conditions. As well as circulation, binding procedures and duplication of sets were seen to affect availability. Indications are that the practice of binding journals upon completion of the volume may remove them from use at a time of peak demand. The usefulness of second sets of journals appeared to decline rapidly within a few years after publication. A change from circulating to noncirculating conditions may have increased availability certain journals by discouraging use.


The reorganization of a monographic reference collection.

Reference monographs in the Health Sciences Library of the College of Medicine and Dentistry of New Jersey were reorganized recently according to form, in order to enable both librarians and patrons to utilize these materials more efficiently. This reorganization reflects the unique characteristics of reference books as differentiated from the regular monographic collection, since reference materials are frequently consulted for quick "look-ups." A reference category scheme was developed and implemented, based on observations of and comparisons with reference collections of eight medical libraries in the New York metropolitan area. The reorganization enhances the retrievability of materials from this collection.


TWX and interlibrary loans; one library's experience.

Vanderbilt Medical Center Library (VMCL) first installed TWX in 1966, thus joining the teletypewriter exchange (TWX) network. Eight years later (1974), VMCL removed its TWX terminal, mainly as an economy measure. It is the opinion of the author that the benefits derived from using TWX for interlibrary loan do not warrant the cost of the service. VMCL looks forward to a new approach.


Biomedical periodicals in Nigerian Medical Libraries: the medical librarian's dilemma.

The Nigerian medical librarian has an uphill task in his effort to satisfy the journal needs of users of his library. His problems stem from difficulties in the selection and acquisition of journals, delay in postal services, budgetary and other administrative controls, and the changing nature of medical education and health-care services in Nigeria. The librarian's attempts to solve these problems include increased subscriptions to journals and use of interlibrary loans, but the absence of union lists of holdings of other libraries, the heavy cost of photocopying services, and poor postal facilities present another dimension to his problems. Eventually his best solution seems to lie in the establishment of a national center for "least used" journals to serve as a source stock for the country's medical libraries.


NLM Medical Library Resource Improvement Grant Program: an evaluation.

The Extramural Programs, NLM, undertook a staff study to evaluate the Medical Library Resource Improvement Grant Program in order to determine impact on hospital library development and to assess factors significant to regional medical library (RML) network development. Initiated in fiscal year 1971, the improvement grant program provides one-year, one-time grant awards of a maximum of $3,000 to assist in establishing a basic collection of books, journals, and other health science information resources for community hospitals and comparable health facilities. Applicants who received grant awards were compared to applicants who did not receive awards and to nonapplicants, using nine dependent variables, four independent variables, and responses to an RML questionnaire. Results show that the applicants who received awards outperformed the other groups, and that the improvement grant program has been successful in stimulating library development. As a result of this study, the improvement grant program will be modified to support consortium arrangements as well as individual institutions, and to extend the period of grant support to two years. Future grant support will be a maximum of $4,000 in the first year, and up to $3,000 with a provision of $1,000 in matching funds from the grantee in the second year.


The fate of isolated segments of flexor tendons within the digital sheath--a study in synovial nutrition.

A study has been made of the fate of isolated, devascularised segments of profundus tendon replaced within the synovial flexor sheaths in the front paws of adult rabbits. In all the experiments the segments were found to have survived as viable "loose bodies" and no adhesions developed. Active remodelling processes occurred over the cut ends of the segments and degenerative changes were confined to the most deeply lying tissue. The experiments confirm the existence of a synovial fluid pathway of nutrition, concerned, it is suggested, with nourishing the more superficial layers of the tendon.


Cartilage formation from free perichondrial grafts: an experimental study in rabbits.

To study whether free-grafted perichondrium would produce new cartilage, perichondrium taken from the rabbits' ears was transplanted to the subcutaneous tissues of the groin and the back, to the muscles of the back, to the areolar tissue in the neck, and to the parenchyma of the liver. A clot of blood was placed in close contact with the perichondrium at randomly selected recipient sites. Wherever the perichondrium was grafted in the presence of clotted blood new cartilage was produced, irrespective of age and weight of the rabbit. When blood was withheld, little or no cartilage formed. New formation of cartilage began in the first week after transplantation and the cartilage was mature within 7 weeks.


Peripheral effects of fenfluramine.

1 The peripheral cardiovascular effects of the centrally acting anorexigenic agent, fenfluramine hydrochloride, have been investigated in the rat. 2 After intravenous administration of fenfluramine, an immediate hypotensive response, followed by a reflex rise in blood pressure was recorded. This was followed by a prolonged fall in blood pressure which frequently failed to return to pre-drug levels. 3 The antagonists, propranolol and atropine, failed to inhibit this hypotensive effect of fenfluramine. 4 The effects of 5 mg/kg fenfluramine for 1h on the blood pressure responses to the sympathomimetic amines, tyramine, methoxamine and metaraminol were studied. 5 The responses to the indirectly acting tyramine were reduced by 50% following fenfluramine, while those to the directly acting methoxamine remained unaffected by the drug. Responses to metaraminol, an amine with both direct and indirect actions, were also unaffected to a significant degree by fenfluramine. 6 Studies on rat isolated vas deferens again showed that responses to tyramine are greatly reduced following fenfluramine. 7 In addition fenfluramine itself produced spontaneous contractions of the vas deferens. These contractions were blocked by the alpha-adrenoceptor blocking agents phentolamine and thymoxamine. 8 It is suggested that fenfluramine exerts an effect at the adrenergic nerve terminal, either by displacing noradrenaline stores or by inhibition of the amine uptake process.


Analysis of the effects of p-methoxy-phenylethylamine on spinal cord neurones.

1 Para-methoxyphenylethylamine (PMPEA) was applied microiontophoretically onto interneurones and motoneurones in the spinal cords of acute spinal cats anaesthetized with alpha-chloralose. Its effects were compared with those of noradrenaline (NA) and 5-hydroxytryptamine (5-HT). 2 PMPEA had effects on interneurones which were similar to those of NA and/or 5-HT; its action was predominantly depressant, and it rarely affected interneurones which could not be influenced by NA or 5-HT. 3 The actions of PMPEA on interneurones excited by electrical stimulation of leg nerves showed that the population of interneurones influenced by the drug coincides with the population affected by NA and 5-HT and by intravenously administered PMPEA. 4 Renshaw cells, which are depolarized by intravenous PMPEA, were hyperpolarized by micoiontophoretically applied PMPEA. 5 Alpha motoneurones, which are depolarized by intravenous PMPEA, were hyperpolarized by micoiontophoretically applied PMPEA. Antidromic firing of the cells could be blocked by PMPEA. 6 The differences between the effects of intravenous infusion and the iontophoretic application of PMPEA upon motoneurones is most easily explained by inhibition of interneurones and a concomitant disinhibition of motoneurones. A similar mechanism may also account for the different effects seen with intravenous and iontophoretic application of PMPEA on Renshaw cells.


Compounds designed to fit a site of known structure in human haemoglobin.

1 The three-dimensional coordinates of the atoms in human haemoglobin are known, and there is a specific site in the deoxygenated form of the protein at which 2,3-diphosphoglycerate (DPG) interacts. 2 Molecular models of this site have been constructed and used to design compounds which should bind to the deoxy conformation and stabilize it. These compounds should therby promote oxygen liberation, as does DPG. 3The compounds so designed were found to promote oxygen liberation. Their relative potencies, as assessed by sigmoidal dose-response curves, are in the predicted sequence.


Nature of histamine receptors in the emetic chemoreceptor trigger zone.

1 The protective effects of the intracerebroventicular (i.c.v.) administration of the H1-receptor antagonist, mepyramine and the H2-receptor antagonists, burimamide and metiamide on centrally induced histamine-emesis were studied in unanaesthetized dogs. 2 The PD50 values of intraventricular mepyramine, burimamide and metiamide against the 100% emetic dose of histamine (3.0 mg i.c.v.) were found to be approximately 200 mug, 20 mug and 20 mug respectively. 3 Although burimamide (i.c.v. or i.v.) afforded protection against histamine-induced emesis, there was no protection against intravenous apomorphine-or oral copper sulphate-induced emesis. 4 The results suggest that both H1- and H2-histamine receptors in the emetic chemoreceptor trigger zone of the area postrema are concerned in histamine-induced emesis.


Effects of several inhalation anaesthetics on the kinetics of postsynaptic conductance changes in mouse diaphragm.

1 Miniature endplate currents were recorded with extracellular electrodes in mouse diaphragms in order to measure the kinetics of the conductance change produced by acetylcholine. Miniature endplate potentials (m.e.p.ps) were recorded intracellularly in the same fibres in which the currents were being recoreded. 2 The general anaesthetics, ether, halothane, chloroform and enflurane at low (anaesthetic) concentrations increased the rate of decay of miniature endplate currents (m.e.p.cs) and reduced the amplitude of m.e.p.ps in this way. 3 At high concentrations the anaesthetics caused a reduction in the amplitude of both m.e.p.cs and m.e.p.ps, and a decrease in the rate of decay of the currents. With halothane and enflurane the decay of some currents became biphasic, with a prolonged tail. 4 It was proposed that the increased rate of decay of the conductance caused by the four agents at anaesthetic concentrations is due to an increase in the fluidity of the subsynaptic membrane. Prolongation of the currents at higher concentrations may be caused by an increase in membrane dielectric constant. 5 The effectiveness of the four anaesthetics in producing a 30% decrease in the time constant of decay of m.e.p.cs was shown to be related to their oil/water partition coefficients and followed closely the relationship between anaesthetic potency and oil/water partition coefficient. It is suggested therefore that the four anaesthetics may produce anaesthesia by changing the kinetics of postsynaptic conductance changes at synapses, perphaps by increasing membrane fluidity.


Ontogenesis of enzyme systems deaminating different monoamines.

1 A detailed investigation into the postnatal development of the activity of the enzyme monoamine oxidase (MAO) in the rat and domestic pig was carried out. 2 MAO activity was measured in littermate male rats aged between 3 and 122 days belonging to six breeding colonies. The tissues studied were three brain regions in which monoamines may play a role in neuronal transmission (septum, hypothalamus, corpus striatum) and, for comparison, in the cerebellum. Liver, heart and adrenal glands were the peripheral organs studied. The following substrates were used to measure MAO activity in each tissue homogenate: kynuramine, tyramine, dopamine, tryptamine and 5-hydroxytryptamine (5-HT). 3 MAO activity towards kynuramine, tyramine and dopamine increased after birth in all brain regions and also in the liver, to reach maximal values between days 40 and 80. In the heart and the adrenal glands enzyme activity remained low up to 30-40 days and then increased steeply. This was the case in all litters examined. 4 All tissues deaminated more tyramine than dopamine. In the liver, the ratio of the quantities of tyramine deaminated/dopamine deaminated was approx. 2 at all ages. In the homogenates of whole brains (including or excluding the hypothalamus and striatum) this ratio was also 2 at all ages. In contrast in the isolated striatum and hypothalamus it was first much higher and reached a value of 2 only at an age of about 20 days. This may indicate an independent development of a dopamine and a tyramine deaminating enzyme system in discrete brain regions. It was suggested, that the low ability to deaminate dopamine in discrete brain regions may be due to the local presence of an enzyme inhibitor which becomes too diluted to be active in homogenates of whole brain. 5 Deamination of tryptamine in the striatum decreased between day 5 and 20 in 3 out of 4 colonies tested. There was a large fall in the deamination of 5-HT in all tissues of one group of rats, but in another 4 groups the tissues of the 5 day old rats deaminated smaller amounts of 5-HT than those of the older rats. 6 Purified hypothalamic mitochondria from 40 day old rats deaminated more tyramine and dopamine but not tryptamine per mg protein than those from 5 day old rats. 7 In the domestic pig there was a significant rise in the values in hippocampal MAO activity towards dopamine and tyramine from the foetus (55 day gestation) to the 1 week old piglet. A further steady rise up to week 6 was indicated, but this rise was not statistically significant. The difference between rat and pig probably reflected the much higher degree of maturity of the latter at birth. 8 In the hippocampus of the pig the ratio between the amount of tyramine deaminated/dopamine deaminated decreased from greater than 10 (foetus) to 4.8 in the 6 week old pig and 2 in the adult.


Comparative effects of propranolol and practolol in the early stages of experimental canine myocardial infarction.

1 The effects of propranolol and practolol, at equivalent myocardial beta-adrenoceptor blocking doses, (as assessed by the degree of shift of isoprenaline dose-response curves) were investigated in anaesthetized greyhounds before and after acute coronary artery ligation. 2 When administered intravenously to the intact close-chest dog, propranolol (0.1 mg/kg) and practolol (0.5 mg/kg) caused similar decreases in heart rate, left ventricular dP/dt max, myocardial blood flow and cardiac output. Only propranolol increased peripheral vascular resistance. 3 When administered 2-3h after acute coronary artery ligation, propranolol (0.1 mg/kg) significantly decreased blood flow in both normally perfused and ischaemic regions of the heart. There was also electrocardiographic evidence of further deterioration after propranolol; two out of seven animals died following this treatment. 4 Practolol (0.5 mg/kg) when administered after coronary artery ligation also decreased normal myocardial blood flow but flow in the ischaemic area remained unchanged. Evidence was obtained from electrocardiographic, myocardial temperature, myocardial O2 consumption and lactate measurements that the administration of practolol, in contrast to propranolol, benefited the ischaemic myocardium. 5 Analysis of the results suggests that this beneficial action of practolol may be related to at least two mechanisms. Firstly the ability of practolol to increase the period during diastole when perfusion of the subendocardium is possible, without decreasing the transventricular pressure during this period. Secondly that practolol does not unmask alpha-adrenoceptor vasoconstriction in the ischaemic region.


Identification of separate receptors for adenosine and adenosine 5'-triphosphate in causing relaxations of the isolated taenia of the guinea-pig caecum.

1 The mechanisms by which adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP) and adenosine relax the taenia caecum preparation of the guineapig have been studied. ATP and ADP produced similar effects which were qualitatively different from those of AMP and adenosine. 2 2-2'Pyridylisatogen tosylate (PIT: 50 muM for 30 min) blocked the effects of ATP and ADP, but exhibited weak activity against AMP and failed to antagonize the effects of adenosine. The action of PIT was unaffected by the inclusion of dipyridamole (2muM) in the bathing fluid. 3 There was a significant correlation between the sensitivity of individual preparations to ATP or ADP and the blocking potency of PIT. 4 The presence of adenosine in the bathing fluid (2 mM for greater than 30 min) desensitized the taenia to subsequent applications of adenosine. The effects of ATP were increased by this procedure. 5 The results indicate that ATP and adenosine relax the taenia by different mechanisms.


Problems in the interpretation of cognitive abnormalities in schizophrenia.

This study compared matched groups of patients with acute schizophrenia and with depression on three tests used in the assessment of schizophrenic thinking disorder. Most measures derived from these tests significantly differentiated the groups; however, within the schizophrenic group there were no significant correlations between scores on the three tests. Further data were available from a choice reaction-time card-sorting task, from which estimates of distractability, stimulus decision time, response decision time, and movement time, were obtained. Only one significant relation was found between these measures and scores on the clinical tests. The possible confounding effects of intelligence and responsiveness are discussed. It is argued that more direct measures of the latter are preferable to interpreting tests of thinking disorder in terms of information processing deficits.


The relationships between obsessional personality, obsessions in depression, and symptoms of depression.

The relationships between obsessional personality, obsessions in depression, and symptoms of depression were investigated by means of a retrospective study of case notes and item sheets. One hundred and sixty-eight cases of depression, aged 20 to 29 years, were rated for obsessional personality as defined by Ingram (1961). The presence of previous obsessions, of obsessions in depression and of eight symptoms of depression was assessed from the item sheets. Obsessional personality was found to be significantly associated only with a decreased frequency of objective apathy, although it seemed to act to reduce the anxiety experienced by those with obsessions, in depression. Obsessions in depression were associated with rapid changes of mood, anxiety, agitation and overactivity and with a relative absence of retardation.


Seasonal variation in the incidence of mania.

The seasonal variation of admissions to hospital with a diagnosis of mania (296.1) in England and Wales was examined. The results indicated that for females there was a significant seasonal trend, the peak being in August-September, while for males there was no significant seasonal pattern. The possible reasons for these findings are discussed.


The season of birth of siblings of psychiatric patients.

The season of birth of the siblings of psychiatric patients was studied to test the hypothesis that an unusual seasonal pattern of maternal conception is the cause of the excess of births in the early months of the year which has been found in national studies of psychotic patients. Information on the month of birth of the siblings was obtained from interviews with psychiatric in-patients born in Britain. The quarterly distribution of births of 670 mentally well siblings of psychotic patients (schizophrenia and manic-depression) was significantly different from that of 1,513 siblings of other psychiatric patients and also from that of all births in England and Wales. The results lend qualified support to the hypothesis, but they were not clear-cut and there was some evidence that the information on birth dates was biased.


The nature of bodily symptoms.

Psychiatric descriptions of bodily symptoms have usually been derived from narrowly restricted clinical experience. It is argued that it is more useful to review evidence from all medical settings and occurrence, nature, disability and presentation are here discussed. Syndromes of hypochondriacal reactions appear to be extreme and uncommon manifestations of a universal potential.


A comparison of two psychiatric screening tests.

A comparison is made between the General Health Questionnaire (GHQ) and the Symptom Checklist (SCL) as psychiatric screening tests in community-based research projects. Both are shown to correlate equally well with independent clinical assessment, and the differences between them mainly reside in the form of their response scales. The GHQ works best as a screening test, since it has fewer false positives associated with its use, but it may miss those with long-standing disorders. The SCL tends not to miss long-standing disorders and furnishes diagnostic sub-scales if these are required. Both tests function better with men than with women and with whites than with blacks, but neither is affected by social class or age of the respondent. The study revealed high correlations between the symptoms of anxiety and depression, and indicated some possible differences between the symptom clusters seen in whites and in blacks.


The Clifton Assessment Schedule - further validation of a psychogeriatric assessment schedule.

This paper is concerned with the further evaluation of the Clifton Assessment Schedule (CAS), a brief psychogeriatric assessment procedure, providing a cross-validation study on a second sample of acute elderly psychiatric admissions. Additionally, further work is reported on its use with a psychogeriatric population resident within the hospital. The results suggest the usefulness of the CAS across a broad range of psychogeriatric patients, providing significant differentiation between groups receiving varying degrees of care and with differing outcome expectations.


Towards a family approach in a psychiatric day hospital.

In a day hosptial all staff members must be able to make rapid decisions, even when they cannot refer to their seniors. It is difficult to develop this capability in a teaching day hospital where the staff and student groups are constantly changing. It has, however, been facilitated by regular staff discussions with a visiting psychotherapist. In these staff groups, the study of role attributions and dynamics characteristic of families has diminished the interference caused by 'family' type dynamics in daily professional interaction. The paper describes the effect of such discussion in stimulating the adoption of a treatment approach which takes the family situation into account. This family approach is distinguished from family therapy, and its advantages are discussed.


Patients have been let out of wards; why not nurses too?

Tradition retains the practice of attaching mental nurses to wards rather than to groups of patients, even though the wards are increasingly empty as patients come to lead more active lives in hospital. A system is described which enables nurses to relate more fully to the people in their care instead of having to confine their activities to the place in which only a part of the care is provided. This system involves all ward nurses in leaving their wards empty in 'working hours', being relieved of the care of their intercurrently ill patients and undertaking in exchange the complete day care of their fitter patients in both wards and workplaces. The consequences of these changes are attractive to many nurses and helpful to many patients.


Acquired sensory control of satiation in man.

Lean male and female subjects who had been taking their meals as usual were given a 100 ml drink of starch immediately before a sandwich lunch. In the training phase,65 per cent starch was given before lunches which included a yoghurt-based dessert of one flavour and 5 per cent starch was given before another flavour. Subjects who initially ate lunches of similar size following the two drinks began after several pairings to take larger lunches following dilute starch than following concentrated starch. In extinction tests, identical 35 per cent starch drinks were given before lunches including desserts of either flavour. Lunches including the flavour hitherto paired with dilute starch remained larger than lunches including the other flavour, at least initially in extinction. Some of the difference in intake occurred in the dessert itself. None was attributable to differences in the early stage of the lunches. These results extend to man recent demonstrations that the satisfying power of a foodstuff is in part acquired by association of its sensory characteristics with some consequence of ingesting the nutrients which are consistently taken with or in that food. This consequence may be rapid intestinal absorption of glucose during or shortly after sensory input. The nature of the intake-suppressing response remains to be determined.


Effects of novelty and oddity on visual selective attention.

Effects of novelty and of oddity on selective attention was investigated through tachistoscopic recognition. When a pre-exposure field consisted of dots of one colour, letters of a different colour were more likely to be identified than letters of the same colour. In displays of 10 letters, two letters differing in colour from the remainder were more likely to be identified. Tachistoscopic exposure precluded determination of responses by eye movements, and there were controls for chromatic adaptation and other factors that might have biased the results.


Conditioning afterimages: a procedure minimizing the extinction effect of normal test trials.

Six subjects were trained on a conditioning schedule of ten trials a day for 25 days: a further 18 CS-US pairings were presented on 4 subsequent days. The tone employed as the CS was put on 30 sec before the presentation of a briefly illuminated visual target (the US) and maintained until terminated by the subject when his afterimages disappeared. This procedure allowed continuous monitoring of the evolution of the conditioned response (conditioned afterimages): directly for CRs with a latency of less than 30 sec which could occur on every training trial before the US was presented; indirectly from the changes in the duration of afterimagery following the presentation of the US. As every trial yielded some evidence about the evolution of the CR, unreinforced test trials were not necessary after every block of training trials so minimizing the extinction effect attributable to the presentation of an unreinforced CS. In the course of the experiment the mean duration of afterimagery increased almost fivefold with one subject showing a tenfold increase. Five of the subjects experienced visual images in response to the tone alone and were judged to be conditioned. The data are discussed in relation to the evolving levels of conditioning identified by Bzhalava (1958, 1965).


Reproduction of Kohs-type figures by Ghanaian children: orientation errors revisited.

First, a relationship was postulated between the experienced difficulty of patterns and the amount of disorientation of their reproductions. Secondly, while the major determinants of gross orientation errors among Africans seem to have been established, this in itself fails to explain why Europeans are little affected by them. It was proposed that the underlying factor might be the development of the concept of horizontality, which reduces dependence on the perceptual pull of the prevailing spatial framework. These notions were tested with 44 Ghanaian schoolboys aged between 10 and 16. The first relationship was clearly confirmed. As for the second, there was some association between horizontality and rotation errors, but it failed to account for a major part of the variance. Ex post facto exploration of the data strongly suggests that degree of psychological differentiation is likely to be the key factor influencing rotation error.


The number and kind of invariant personality (Q) factors: a partial replication of Eysenck and Eysenck.

A study by Eysenck & Eysenck (1969) investigated the invariance across sex of factors derived from the Eysenck, Cattell and Guilford personality inventories. They found only neuroticism and extraversion invariant. The present study was designed as a partial replication of their study, but employed simpler, common-sense methods that gave the more moderate sized factors a chance to demonstrate the extent of their invariance across sex. Four invariant factors were found: the first two, neuroticism and sociability, were large and demonstrated almost complete invariance across sex; the third and fourth factors were moderate-sized and showed less, but substantial invariance across sex. They were called 'sensitivity v. practicality' and 'group-centred morality v. self-centred independence'.


The specificity of schizophrenic thought disorder: a replication and extension of previous findings.

Eight thought-disordered schizophrenics, eight non-thought-disordered schizophrenics and eight normal subjects each completed four repertory grids, formed by combinations of two types of construct, psychological and physical, and two types of element, photographs and known people. The finding of McPherson & Buckley (1970) that thought-disordered schizophrenics are relatively less disordered when using physical constructs than when using psychological constructs was replicated. Further, this specificity of schizophrenic thought disorder was extended from grids employing photographs of strangers to grids employing known people, thus disconfirming an explanation of schizophrenic grid performance (Williams, 1971) in terms of 'cue insensitivity'.


Choice reaction times in depressive states.

An experiment was performed in which two components of response latency, decision time (DT) and movement time (MT), were measured in two relatively homogeneous samples of neurotic and psychotic depressive patients, together with a normal control group. It was found that whereas both DT and MT were significantly longer in the depressive samples than in the control sample, only DT was significantly longer in the psychotic than in the neurotic depressive sample. Thus while both DT and MT were elevated among the depressive samples relative to the control sample, only DT was further sensitive to clinical variations within the depressive state. DT was found to increase directly with depressive severity among an undifferentiated sample of acute depressives, which on further analysis proved to hold for the neurotic depressive sample only. MT was found to increase directly with age among the psychotic depressive sample. No other age influences were found on response latencies of depressive patients. These results are discussed in terms of a postulated impairment of the central information-processing mechanisms, as an explanation of psychomotor slowing among depressive patients.


The measurement of expressed emotion in the families of psychiatric patients.

In a series of studies of the influence of family life on the course of an established schizophrenic illness, it has been shown that the level of emotion expressed by relatives shortly after a schizophrenic patient is admitted to hospital is strongly associated with symptomatic relapse during the nine months following discharge (Brown et al., 1962, 1972). This paper states the case for an abbreviated version of the primary research instrument used in these studies, the Camberwell Family Interview Schedule. In the 1972 study the single most important measure contributing to the overall expressed emotion index proved to be the number of critical remarks made about the patient by the relative when interviewed alone. An analysis of 15 tape-recorded interviews from this study showed that the majority of critical comments were produced within the first hour and there was virtually no relationship between total number of critical comments and length of interview (r = 0.08). This analysis supported the use of a shortened interview in which the areas most likely to produce any criticism were given priority in the sequence of questioning. This abbreviated version has been used successfully in a replication and extension of the 1972 study. A group of 37 schizophrenic patients is being compared with a group of 31 depressed neurotic patients. Patterns of emotional response of these patients' relatives are discussed.


A further attempt to cross-validate the grid test of schizophrenic thought disorder.

A retrospective investigation to assess the validity of the Grid Test of Schizophrenic Thought Disorder (Bannister & Fransella, 1966, 1967) is reported. Analysis of the data revealed that, while there is some evidence to support the validity of the test, it failed to discriminate between clinically assessed thought-disordered and non-thought-disordered patients at an acceptable level of significance, and that the rate of misclassification was too high to justify the use of the test in the assessment of an individual case. The results are compared with the findings of other published studies, and weaknesses in methodology, due to the retrospective nature of the study, are also discussed.


Attention and information processing in schizophrenia.

The performance of 20 acute schizophrenics and 10 depressives, matched for age, verbal intelligence, and pre-morbid functioning, was assessed on a choice reaction-time card-sorting task. Stimulus and response uncertainty were varied independently, and there were two main conditions, distraction and no distraction. The schizophrenics were slower than the depressives over all the functions examined in the study. Schizophrenics were significantly more affected by increases in response uncertainty than the depressives. Although there was a tendency for the schizophrenic group to be more affected by distraction and by increasing stimulus uncertainty, these differences were not significant. There was no significant interaction between the effects of stimulus and response uncertainty, nor between the effects of distraction and stimulus uncertainty. The effects of distraction increased with increasing response uncertainty. The results are discussed in relation to two models of information processing, suggested by Broadbent (1971) and by Sternberg (1969). Such models allow a more detailed examination of the cognitive abnormalities found in schizophrenia.


Bone disease in long-term haemodialysis: the association of radiological with histological abnormalities.

The radiological findings in the skeletal surveys of 70 patients receiving long-term haemodialysis for chronic renal failure have been correlated with histological findings in a specimen obtained by biopsy of the iliac crest. Many significant associations were found, and the ones presented are those thought to be most useful in the interpretation of the radiological abnormalities. The main conclusions are that fractures and severe medullary rarefaction appear to be most commonly the result of osteomalacia; subperiosteal erosions are associated with the more severe grades of osteitis fibrosa; cortical striations and sclerosis are associated with an increased amount of osteoid, and sclerosis is diagnosed more frequently by radiological means than by iliac-crest biopsy.


Loss of renal tissue in the elderly.

Eighty-eight kidneys obtained at necropsy from normotensive subjects aged over 50 years were examined histologically and by post-mortem pyelography and angiography. Moderate or severe scarring was present in 50%. Its distribution and the absence of calyceal deformity make pyelonephritic scarrig unlikely. Its extent was related to the severity of change in the renal vessels, but not to age. On pyelograms, scarring was difficult to distinguish from fetal lobation. Kidneys with the most severe histological changes in the vessels tended to show the most marked angiographic distortion, though in general the two techniques examine different parts of the renal vascular bed. Total renal area and "cortical" area, measured from the angiograms, were not significantly correlated with age, thouth both tended to be smaller in older subjects. These dimensions, particularly cortical area, were significantly correlated with vascular changes, being smallest when vessels were most markedly affected. Results suggest that the loss of renal tissue which occurs in the elderly, particularly selective loss of cortex, is more closely related to events in the renal vasculature than to age itself.


Septal lines in pure right heart failure.

Two adult patients are described with pure right heart failure and chronically elevated systemic venous pressure. Neither patient had evidence of pulmonary venous hypertension, but both had septal lines. This unusual finding may be the result of impaired centripetal lymph flow in the lungs due to obstruction of the drainage of the thoracic duct by raised systemic venous pressure.


The absorbed dose to bone marrow in the treatment of polycythaemia by 32P.

This paper reports the determination of absorbed dose to bone marrow in the treatment of polycythaemia by 32P, based on the measurement of activities in bone and marrow biopsies taken at various times from 1 to 27 days after injection of the radionuclide. Activities were measured in the cortex, trabeculation and marrow of biopsies taken from the iliac crest, and slso in sternal marrow. The biological  half-life of 32P in marrow from the iliac crest was found to be  nine days; that derived for sternal marrow was lower, but the difference was not statistically significant; the value for trabecular bone was 27 days. The biological half life for 32P in the body, as measured by whole-body counting, was 39 days. Calculations of the dose-rate to trabecular marrow have been made by a method based on that of Whitwell and Spiers (1971), but modified to allow for the presence of32P in the marrow as well as in trabecular bone. The dose-rates follow a single exponetial decay with a half-life of 6.7 days. The intergrated dose including that during the first day is 24 rad per mCi injected.


Bowel gas--a cause of elevated dose in radiotherapy.

The presence of gas in bowel could lead to higher than expected doses being given in the radiotherapy of abdominal and pelvic tumors. Radiation detectors were placed in the uterus and vagina of ten patients with caricnoma of cervix, and the actual dose compared with that expected when anterior fields of treatment were employed. Elvations greater than 10% were obtained in six, and severe postradiation morbidity subsequently occured in two of the three showing the highest readings.


Prediction of human spleen size by computer analysis of splenic scintigrams.

A method of assessing spleen size from splenic scintigraphs obtained using autologous heat damaged 99Tcm labelled red cells is described. The method depends on a "computed volume" estimate. The method has a correlation coefficient of 989 with the exsanguinated weight ofthe spleen after splenectomy and has been shown to have an accuracysuperior to methods previously described.


Gallium-67 imaging to localize urinary-tract infections.

To differeniate upper from lower-tract urinary infections, 73 patients were imaged with 67Ga citrate. Renal uptake of the radioisotope occurred in pyelonephritis (documented in 47 patients by ureteral cathieterization, bladder washout, or  histology) with an accuracy of 86%. There were 15% false-positives and 13% false-negatives. 67Ga may prove to be a clinically valuable test in the diagnosis of pyelonephritis. Results are promptly available 24 hours after injection, and it is non-invasive test that can safely be repeated to follow recurrent infections.


Some in vivo effects of pi mesons in mice.

The effect of 70 MeV pi mesons was studied to determine the effectivness of such beams aginst normal tissues in vivo. The end points included thymic weight loss, oocyte and bone marrow CFU-S survival and the induction of macroscopid lens opacities. The results indicate that pi mesons are not signifacantly more effective for these end-points than more conventional radiation sources such as 60Co gama rays, 220 kVp X rays, and 14 MeV X rays and electrons. Nor was there any detectable difference in RBE between the peak and plateau regions of the pi meson beam. The significance of these findings is discussed in relation of the the published pi meson RBE values of between 1 therefore 4 and 5 therefore 0.


Response of HeLa cells to irradiation with pi- mesons.

HeLa cell suspensions were irradiated at various depths of Perspex in a beam of 70 MeV pi- mesons. The dose-rate in the Bragg peak varied between 40 rad hour-1 and 150 rad hour-1. The cells were assayed in vitro for loss of reproductive integrity. The results for irradiation in the peak indicated an RBE of about 2-1 when compared to the response obtained using 60Co gamma-rays at comparable dose-rates. At dose-rates of 100-150 rad hour-1, the RBE peak-to-plateau was about 1-4, while at lower dose-rates, the RBE peak-to-plateau was about 1.