Sustained depolarizing potentials in reticulospinal axons during evoked seizure activity in lamprey spinal cord.

1. Intracellular recordings were made from lamprey reticulospinal axons (Müller axons) during seizures evoked by electrical stimulation of the isolated spinal cord in saline containing either 0 Cl or 1 mM picrotoxin. The seizures had tonic and clonic-phases similar to ictal seizures in mammalian brain. 2. During seizures Müller axons were depolarized by 10-15 mV. These seizure-depolarizations were not due to any direct effect of the evoking stimulus on the Müller axons themselves nor were they initiated by an accumulation or extracellular potassium. 3. A decrease in axonal input resistance occurred during a seizure-depolarization. Also, the amplitude of a seizure-depolarization was decreased by depolarizing the axon 5-15 mV with injected current. Further, hyperpolarizing the axon increased the amplitude of the seizure-depolarization, but the growth flattened out beyond 30-40 mV of hyperpolarization. The decrease in input resistance during the seizure-depolarization and the dependence of the response amplitude on axonal membrane potential suggested that the seizure-depolarization was an excitatory synaptic potential. However, the failure of the seizure-depolarization amplitude to continue to grow at membrane potentials greater than 30 mV negative to the resting potential was not consistent with this interpretation. 4. A synaptic conductance change as the cause of the seizure-depolarization was ruled out by setting the axonal membrane potential at different levels with injected current and monitoring the input resistance of the axon before and during seizure-depolarizations. It was found that no change in input resistance occurred during the seizure-depolarization when the axon was hyperpolarized more than approximately 30 mV, the same potential at which the growth in the response amplitude ceased. From analysis of these data and the passive current-voltage properties of Müller axons it is concluded that the seizure-depolarization is not a chemical synaptic potential, but rather the result of the passive injection of depolarizing current into the axons. 5. The source of the depolarizing current which flows into Müller axons during seizures is probably paroxysmal action-potential activity in spinal motoneurons and interneurons, many of which are electrically coupled to Müller axons.


Stimulus-response relations and stability of mechanoreceptor and motor neurons mediating defensive gill-withdrawal reflex in Aplysia.

1. A weak or moderate-intensity tactile stimulus delivered to the siphon skin of Aplysia californica elicits a defensive reflex withdrawal of the gill and siphon into the mantle cavity. The reflex undergoes both short- and long-term habituation and sensitization and has, therefore, been used as a model system to examine various forms of learning. In this paper we describe studies of the response properties of the sensory and motor neurons of the reflex during repeated stimulation at rates that produce habituation. 2. The sensory neurons are slowly adapting mechanoreceptor cells whose frequency of discharge is a monotonic function of controlled-force punctate stimuli delivered to the skin. The majority of the stimulus-response relations could best be described by exponential functions. 3. We examined the stability of the sensory neuron responses in two ways; with punctate stimuli of varying intensity and with water jets of varying intensity. 4. With repeated punctate stimulation at rates which produce habituation in the intact animal the mechanoreceptor discharge showed no decrement. This stability was observed over a 10-fold range of intensities. 5. Weak or moderate intensity water-jet stimuli to the skin also gave stable responses but stronger stimuli caused the mechanoreceptor response to fatigue. 6. We examined the stability of the motor responses by using intracellular depolarizing current pulses to produce repetitive bursts of action potentials in gill motor neurons while monitoring the gill contractions with a strain gauge, photocell, or videotape recorder. The photocell and strain gauge were alternatively used in the same experiment. Gill contractions monitored with the photocell were stable, whereas those monitored by the strain gauge showed decrement. An independent measure of gill contraction, videotape recording, confirmed the results obtained with the photocell and showed that the gill contractions following repeated intracellular depolarization of the motor neurons were stable.


Contribution of individual mechanoreceptor sensory neurons to defensive gill-withdrawal reflex in Aplysia.

1. To evaluate the contribution which mechanoreceptor sensory neurons make to the defensive gill-withdrawal reflex we developed an isolated reflex preparation. We then reduced this isolated reflex to a microcircuit (consisting of a single sensory cell and single motor cell) so as to causally relate the contribution of individual cells to the expression and plastic properties of the behavior. 2. Mechanoreceptor neurons make significant contributions to the amplitude and duration of the complex PSP in the motor neurons. A single spike in a sensory neuron produces an EPSP in the motor neuron which accounts for 7-36% of the complex EPSP produced by weak tactile stimulation of the skin. 3. More than 50% of the synaptic input to the gill motor neurons appears to be monosynaptic. Perfusing the ganglion with solutions of high divalent cations reduced the motor neurons' complex PSP by only 40%. 4. The population response of the mechanoreceptors to a point stimulus can be simulated by repetitively firing a single sensory neuron. Firing a single sensory cell discharges the motor neuron and produces a gill contraction similar to that produced by a natural stimulus. 5. Mechanoreceptors make monosynaptic connections onto gill motor neurons which decrement with repeated stimulation paralleling the decrement of the complex PSP to punctate tactile stimulation of the skin. 6. The results indicate that the known neural elements may quantitatively account for most of the expression of the behavior and its short-term habituation.


Neural transduction in Xenopus laevis lateral line system.

1. The process of neural excitation in hair cell systems was studied in an in vitro preparation of the Xenopus laevis (African clawed toad) lateral line organ. A specially designed stimulus chamber was used to apply accurately controlled pressure, water movement, or electrical stimuli, and to record the neural responses of the two afferent fibers innervating each organ or stitch. The objective of the study was to determine the characteristics of the neural responses to these stimuli, and thus gain insight into the transduction process. 2. A sustained deflection of the hair cell cilia due to a constant flow of water past the capula resulted in a maintained change in the mean firing rate (MFR) of the afferent fibers. The data also demonstrated that the neural response was proportional to the velocity of the water flow and indicated that both deflection and movement of the cilia were the effective physiological stimuli for this hair cell system. 3. The preparations responded to sinusoidal water movements (past the capula) over the entire frequency range of the stimulus chamber, 0.1-130 Hz, and were most sensitive between 10 and 40 Hz. The variation of the MFR and the percent modulation indicated that the average dynamic range of each organ was 23.5 dB. 4. The thresholds, if any, for sustained pressure changes and for sinusoidal pressure variations in the absence of water movements were very high. Due to the limitations of the stimulus chamber it was not possible to generate pressure stimuli of sufficient magnitude to elicit a neural response without also generating suprathreshold water-movement stimuli. Sustained pressures had no detectable effect on the neural response to water-movement stimuli. 5. The preparations were very sensitive to electrical potentials applied across the toad skin on which the hair cells were located. Potentials which made the ciliated surfaces of the hair cells positive with respect to their bases increased the MFR of the fibers, whereas negative potentials decreased it. The responses to sinusoidal electrical stimuli were similar to responses to water-movement stimuli with respect to frequency and dynamic ranges. Thresholds as low as 100 muV peak to peak (p-p) for 16-Hz stimuli were found. 6. The characteristics of the neural responses to electrical stimulation as well as supporting data obtained from the studies of the effects of anoxia on the evoked responses indicate that the electrical stimulus acts on the hair cells or on the synapses, rather than directly on the nerve fibers. This finding suggests that receptor potentials or their associated currents play an important role in the process of neural excitation in hair cell systems.


Intracellular staining reveals different levels of stratification for on- and off-center ganglion cells in cat retina.

1. Ganglion cells in the retina of the cat were stained by intracellular dye injection after recording their responses to photic stimulation. 2. All cells encountered were divided into those giving on-responses and those producing off-responses, and the level of dendritic branching of these two groups was compared. Cells giving off-responses were found to branch high in the inner plexiform layer (IPL), near the amacrine cell bodies (sublamina a); those giving on-responses were found to branch lower in the inner plexiform layer (sublamina b). 3. Dye-injected cells varied widely in morphology and size, having cell bodies ranging in diameter from 8 to 32 micrometer and dendritic fields ranging from 25 to 490 micrometer in diameter; yet the sign of the response of each unit correlated only with the level of dendritic branching. Thus, no other morphological feature except stratification appears to be important in determining the sign of the response of these cells. 4. The stratification of ganglion cells into on- and off-layers parallels the distribution of the axon terminals of the flat and invaginating cone bipolars. Flat cone bipolars are in a position to contact off-center ganglion cells (in sublamina a) and invaginating cone bipolars are in a position to contact on-center ganglion cells (in sublamina b). 5. The rod and cone inputs to some cells were characterized by comparing their responses to deep red and blue rod-matched stimuli over a 2-log unit range starting at dark-adapted threshold. About half the cells appeared to be rod dominated under these conditions, whereas the others appeared to have mixed rod and cone signals. 6. The nature of the rod and cone pathways to ganglion cells is discussed.


Corticopontine cells in area 18 of the cat.

1. Area 18 projects to the rostral pontine nuclei. The visual response properties of rostral pontine cells differ greatly from those that have been reported for area 18 cells. We identified and studied corticopontine cells in area 18 and compared their receptive-field properties to those of other area 18 cells and to pontine visual cells. 2. We first located the visual area in the rostral pons by microelectrode recording and placed stimulating electrodes at the same site. Anti-dromically invaded cells were then recorded in area 18. The antidromic invasion of each cell was verified by orthodromic-antidromic spike collision. 3. Fifty-seven well-isolated corticopontine cells were studied in detail. We also recorded 466 unitary antidromic potentials with a mean invasion latency of 3.5 ms and recorded from 40 additional area 18 units to serve as a comparison group for the corticopontine cells. The comparison group cells were located in the same area in the visual field as the corticopontine cells. 4. The average receptive-field area for corticopontine cells (485 deg2) was much larger than the comparison cells (59 deg2). Forty percent of the corticopontine cells responded preferentially to multiple-spot target. Properly oriented gratings, slits, or edges were the most effective stimuli for the comparison cells. Eighty-two percent of the corticopontine cells showed clear directional preferences to moving-spot stimuli, and downward movements were most commonly preferred. Fifty-five percent of the area 18 comparison cells showed some directional preference, but no particular direction was preferred. The optimal stimulus speeds for corticopontine cells were higher than those for the comparison cells. 5. The response properties of the area 18 corticopontine cells are similar to the response properties of rostral pontine visual cells, except for a somewhat higher selectivity for orientation in the corticopontine cells. 6. We conclude that most response properties of rostral pontine visual cells are already present in a subset of area 18 cortical cells which project to the pons. The corticopontine cells are sensitive to multiple-spot targets moving in particular directions over large portions of the visual field, such properties are consistent with a visuomotor function for the corticopontocerebellar pathway.


Effect of compensatory hypertrophy studied in individual motor units in medial gastrocnemius muscle of the cat.

1. Compensatory hypertrophy of the medial gastrocnemius (MG) muscle was produced by denervating or removing its synergists (i.e., the lateral gastrocnemius, soleus, and plantaris muscles) in adult cats. Following survival times of 14-32 wk, intracellular recording and stimulation techniques were used to study the motor-unit population in MG. The data obtained were compared with results from MG motor units in normal unoperated cats of the same body size and weight. 2. Using criteria employed for normal motor units, the units in hypertrophic MG muscles were readily classified into the same groups (types FF, F(int), FR, and S) as in normal MG. There was no detectable difference in the distribution of motor-unit types after hypertrophy. 3. When compared with a normal motor-unit sample, there was a large increase in mean tetanic tension, but no significant change in twitch tension, for each motor-unit type in the hypertrophied muscles. The most marked increase was found among the fatigue-resistant type S and type FR motor units. There was no alteration of twitch contraction times or fatigue resistance in any unit type after hypertrophy. 4. For each motor-unit type, the mean homonymous (MG) group Ia EPSP amplitude was the same in normal and hypertrophic MG populations. There was, however, a significant increase in the average conduction velocity of MG motor axons in the animals with uncomplicated MG synergist removal and maximal MG hypertrophy. 5. On the basis of histochemical staining, muscle fibers from comparable sections of hypertrophic and contralateral (unoperated) MG muscles were presumptively identified as belonging to FF, FR, or S units. There was no significant difference between hypertrophic and contralateral MG muscles in the percentage of each fiber type, although there was some variability in muscle composition from one cat to another. One muscle pair was studied in detail for fiber cross-sectional area. In this cat, with marked hypertrophy by muscle weight, there was a modest increase in the mean fiber areas of histochemical S and FR muscle fibers, but no evident change in FF fibers, on the hypertrophic side. 6. MG motor units were examined in several cats in which synergist removal resulted in scarring and marked limitation of passive ankle mobility, and no evident weight gain in MG. Motor units of all types in these animals showed a decrease in twitch tension and in mean twitch/tetanus ratios, with little alteration in mean tetanic tensions. 7. The main effect of compensatory hypertrophy under the present conditions was a large increase in tetanic tension output from individual motor units due, at least in part, to an increase in fiber cross-sectional area. There was no evidence indicating any "conversion" of motor units or of their muscle fibers from one type to another.


Effects of monensin on in vivo rumen propionate production and blood glucose kinetics in cattle.

Four rumen-fistulated steers (154 to 253 kg), fed two different diets in succession, were used to determine effects of monensin on rumen propionate production rates and blood glucose kinetics as determined by single-injection isotope-dilution techniques. A high-roughage and a high-grain diet, with and without 150 mg of monensin daily, were fed isoenergetically at 2-hour intervals. Monensin increased rumen propionate pool sizes from 32 to 57 g for the high-roughage diet and from 37 to 66 g for the high-grain diet and increased rumen propionate production rates from 441 to 659 g/day for the high-roughage diet and from 510 to 899 g/day for the high-grain diet. Molar percentages of rumen propionate were increased significantly by monensin in the high-grain diet. Blood glucose pool sizes were not changed significantly by either monensin or isoenergetic diets. Monensin increased irreversible losses of glucose from 582 to 677 g/day for the high-grain diet. Monensin tended to increase glucose total entry rates for both diets and to increase irreversible loss of glucose for the high-roughage diet but the differences were not significant. Thus, increases in glucose kinetics are minor in contrast to major increases of rumen propionate production caused by monensin.


Heat increment associated with dietary protein, fat, carbohydrate and complete diets in salmonids: comparative energetic efficiency.

The heat increment (HI) of feeding, which is the increased heat production following consumption of food by an animal, accounts for as much as 30% of the ingested metabolizable energy (ME) in mammals and birds. The purpose of these experiments was to measure the HI associated with the feeding of a complete diet and purified fat, protein, and carbohydrate to salmonids. Measured amounts were fed and the heat production was measured by direct calorimetry. Increased heat production was observed about 30 minutes after feeding and remained elevated for 1 to 5 hours, depending on the amount and type of material fed. The HI of protein was much lower with fish than with mammals and amounted to less than 5% of the ingested ME. The HI's of carbohydrate and protein were not significantly different from each other but both were higher than fat. The HI, when complete diets were fed, was less than 3% of the ME. The net energy of protein is higher for fish than for birds or mammals. A major part of the superior energetic efficiency of fish is due to the low energy cost of protein metabolism.


Effects of an essential fatty acid deficiency, pair-feeding and level of dietary corn oil on the hypothalamic-pituitary-gonadal axis and other physiological parameters in the male chicken.

Two studies were conducted to observe the effects of an essential fatty acid (EFA) deficiency, added dietary corn oil and pair-feeding on growth, reproduction and other physiological parameters in the mature cockerel. A purified, linoleic acid (LA)-deficient diet (0.01% LA), or additions of 5% (3.01% LA) or 15% (9.04% LA) corn oil, were fed ad libitum from hatching through 24 weeks of age. Reductions in growth, feed consumption, and comb, and testes size, incomplete spermatogenesis, increased tissue eicosatrienoic acid (20: 3 omega 9) and changes in weights of selected internal organs were observed in deficient cockerels. Total pituitary gonadotropic activity was measured by two bioassay procedures and blood luteinizing hormone was measured by radioimmunoassay. By maturity both of these parameters were significantly reduced in deficient chickens. When these chickens were fed diets with 5% or 15% corn oil under pair-feeding or ad libitum conditions from 20 to 24 weeks, the reduced growth, comb and testes size and gonadotropin metabolism appeared to be caused by depressions in appetite and energy intake rather than EFA per se. The degenerate testicular histology of the 20-week old deficient cockerels, while responding fully to the ad libitum intake of the diets containing corn oil, showed only partial rehabilitation of spermatogenesis when diets with either 5% or 15% corn oil were pair-fed. In general, increasing the level of dietary fat from 5% to 15% did not cause many physiological changes.


Effect of excess dietary L-histidine on plasma cholesterol levels in weanling rats.

Supplementation of a closed formula, cereal based stock diet with excess L-histidine at a 5% or 8% level for 4 days reduced growth and induced hepatomegaly and an increase in plasma cholesterole levels in weanling rats. The enlargement of the liver was in part due to glycogen accumulation; plasma glucose concentration was unchanged. Feeding four different amino acids (L-phenylalanine, L-glutamic acid, glycine and L-tryptophan), at levels which caused reduction of growth comparable to the 5% and 8% L-histidine supplementation, did not effect liver weight or plasma cholesterol levels. L-Threonine added, at a 2% level, to the 8% L-histidine diet did not alleviate any of the histidine effects. Rats fed a diet containing 5% urocanic acid, the first metabolite of the histidine degradative pathway, grew at a normal rate but had higher plasma cholesterol levels compared to rats fed stock diet. When rats fed L-histidine-or urocanic acid-supplemented diets were returned to stock diet, a normal growth rate was resumed immediately and plasma cholesterol levels returned to normal within 6 days. These results suggest that L-histidine and/or urocanic acid induce a hypercholesterolemia which disappears several days after the supplementation ceases.


Calcium metabolism, intestinal calcium-binding protein, and bone growth of rats fed high protein diets.

The rat was used as a model for investigating the mechanism by which the consumption of high diets causes calciuria. Using a combined balance and kinetics study, calcium (Ca) metabolism was studied in 56-day old male rats which had been consuming a control (18% casein) or a high protein (36% casein) diet for 2, 14, or 28 days. Urine Ca was significantly increased to 1.7 mg/day and 1.1 mg/day in rats which consumed the high protein diet for 2 or 14 days respectively. After 29 days of consuming the high protein diet, urinary Ca excretion was 0.7 mg/day, the same as that of controls. No other criteria of calcium metabolism were significantly affected by the high protein intakes. Intestinal calcium-binding protein activity was not affected by consumption of the 36% casein diet for 7 days, nor was bone mineralization after consumption of this diet for 32 days. Since the rat excretes a low percentage of dietary Ca via the urinary route, it is not a useful model for studying Ca kinetics in protein-induced calciuria.


Studies on L-ascorbic acid metabolism in rats under chronic toxicity due to organophosphorus insecticides: effects of supplementation of L-ascorbic acid in high doses.

The effects of chronic administration of two organophosphorus insecticides, parathion and malathion on the growth rate, ascorbic acid metabolism and some other nutritional and physiological parameters in rats were studied. Both parathion and malathion toxicity retarded the growth rate of rats. Inhibition of brain acetylcholinesterase was taken as an index of organophosphorus insecticide toxicity. Haemoglobin concentration of blood and organ weights were not affected under the toxic conditions. Parathion and malathion administration stimulated the activity of L-gulonolactone oxidase along with a simultaneous increase in the tissue storage and urinary excretion of vitamin C. The activities of other enzymes of ascorbic acid metabolism, dehydroascorbatase, uronolactonase, and L-gulonate dehydrogenase and decarboxylase were altered under the experimental conditions. Only minor histological changes of the liver and kidney tissues were noted under parathion and malathion toxicities. Excess intake of vitamin C under the toxic conditions was found to be very effective in counteracting the growth retardation and also the alterations produced by parathion and malathion both at the enzymatic and histological levels.


Hepatic cytosolic non selenium-dependent glutathione peroxidase activity: its nature and the effect of selenium deficiency.

Recent work had indicated the presence of a non selenium-dependent glutathione peroxidase activity in rat liver in addition to the selenium-dependent activity. The present study was undertaken to learn whether the glutathione S-transferases are reponsible for the non selenium-dependent glutathione peroxidase activity and to study the effect of selenium deficiency on those enzymes. Glutathione S-transferase B was purified by an established method using carboxymethyl cellulose ion exchange chromatography and studied. It exhibited glutathione peroxidase activity toward cumene hydroperoxide and t-butyl hydroperoxide. A limiting Km of 0.55 mM was determined for cumene hydroperoxide. Sulfobromophthalein was found to be a competitive inhibitor with respect to cumene hydroperoxide of the glutathione peroxidase activity of glutathione S-transferase B. Selenium deficiency caused an increase in glutathione S-transferase activity. These results establish that glutathione S-transferase B contributes to the non selenium-dependent glutathione peroxidase activity in rat liver and show that it increases in selenium deficiency when the selenium-dependent glutathione peroxidase is decreased.


Cyclic changes in the osmolality and electrolyte composition in the gastrointestinal tract of the rock hyrax.

The rock hyrax has been shown to have a very unusual and complex digestive tract. The gastrointestinal tract is comparable to that of the simple and complex stomach of mammals as well as to that of birds. Determinations of osmolality and electrolytes have been made in different sections of the gut of the hyrax. However, with the exception of the elevated potassium levels observed in the cranial stomach, the hyrax poses no unusual osmotic or electrolyte concentrations when compared to man or other mammals. The greater cation concentration and hypertonicity of the cranial stomach was largely accounted for by the elevated potassium load in this gut segment. Sodium and potassium comprised the major cations present throughout the gastrointestinal tract. Chloride was the major anion observed in the foregut; however, the electroneutrality of the mid and hindgut of the hyrax was primarily maintained by the presence of large concentrations of volatile fatty acids produced in these portions of the gut. Volatile fatty acid also accounted for the high anion concentration and hypertonicity of the cranial stomach.


Rumen propionate and blood glucose kinetics in growing cattle fed isoenergetic diets.

The relationship between rumen propionate production and blood glucose kinetics was examined in four rumen-fistulated Holstein steers fed isoenergetic amounts of 80/20 (G) and 30/70 (R) grain/chopped alfalfa hay diets at 2-hour intervals. Single-injection rumen propionate and blood glucose kinetics were determined in consecutive 4-hour periods by using [6-3H]glucose intravenously then [1-14C]propionate intraruminally. Rumen propionate specific activity was determined after isolation and quantitation by high-pressure liquid chromatography. Average rumen propionate production rates and pool sizes were 441 g/day and 32.0 g when diet R was fed but increased to 510 g/day (P less than 0.05) and 36.5 g (P less than 0.10), respectively, when diet G was fed. Propionate production as related to digestible energy (DE) intake, averaged 0.56 mole/Mcal DE for R and 0.64 mole/Mcal DE for G. Rumen propionate turnover times were similar for both diets. Despite differences in propionate availability, there were no significant dietary differences in glucose kinetic parameters. Average glucose pool sizes and irreversible losses were 27.0 g and 585 g/day for R and 27.0 g and 582 g/day for G.


A respiratory survey of cedar mill workers. I. Prevalence of symptoms and pulmonary function abnormalities.

A respiratory-occupational questionnaire and spirometry were used to compare the prevalence of symptoms and pulmonary function abnormalities in 405 workers exposed to red cedar dust and 252 control workers exposed to other wood dusts. Compared with controls, the cedar workers were found to have a significantly higher prevalence of respiratory symptoms, cough, phlegm, wheeze and breathlessness, as well as more rhinitis and conjunctivitis. While, as expected, there was a clear relationship between respiratory symptoms and cigarette smoking, there was also evidence to suggest a synergistic effect between exposure to cedar dust and smoking. There was no difference in the lung function between cedar workers and controls. Sixty-five workers in the control group previously had worked in red cedar mills; they had a higher prevalence of respiratory symptoms than other workers in this group. Red cedar asthma was found in only 1.1% of the cedar workers. This condition usually develops in the early months of exposure, and workers who are affected tend to leave the industry. The probable incidence of red cedar asthma was estimated to be higher, around 4-5%.


Pleuropulmonary disease among asbestos workers in relation to smoking and type of exposure.

The chest roentgenograms of employees aged 40 and over in two asbestos manufacturing plants were read by consensus without knowledge of the plant or smoking habits. Plant A used only chrysotile asbestos throughout its history and Plant B used amosite as well as chrysotile, the amosite being limited to the period 1950-64. The prevalence of pulmonary disease was 25% in Plant A and 33% in Plant B. The prevalence of pleural thickening was 18% in Plant A and 35% in Plant B. Neither age nor work duration were factors in these differences. In Plant A there was no obvious relationship between smoking and pleuropulmonary disease. In Plant B there was a definite relationship of smoking to pulmonary disease and perhaps to pleural thickening. Both type of asbestos and smoking habits appear to be determinants of pleuropulmonary disease in asbestos workers.


Incidence of cardiovascular diseases in the Dutch viscose rayon industry.

An investigation was made into the incidence of cardiovascular diseases in the Dutch viscose rayon industry. The first part of the article discusses a further study, complementary to a pilot study conducted in 1974, into the distribution of cardiovascular cases among the various departments of a rayon plant. No differences in the frequency of cardiovascular cases in departments with and departments without CS2 were observed. The second part deals with a case-control study in which the total number of patients per plant was matched with comparable individuals not suffering from cardiovascular disease. Here, too, it was not possible to demonstrate a significant correlation between CS2 exposure and cardiovascular diseases. The third part describes a cohort study. Three cohorts were formed: (1) a cohort of shift workers exposed to CS2; (2) a cohort of shift workers not exposed to CS2; and, (3) a cohort of non-shift workers not exposed to CS2. With a three-year interval, these cohorts were examined twice for cardiovascular diseases, with reference to a checklist of 39 variables. Again, no significant differences between the cohorts could be shown to exist.


An alternative phototherapy light combination.

Combinations of fluorescent lamps for phototherapy were evaluated in order to select one that maximizes blue light content (400 to 500 nanometers) for most effective photodegradation of bilirubin, maintains acceptable color balance for observing infant skin color, and requires minimal lamp replacement for low maintenance cost. The combination that best achieves these objectives consists of four special blue (Westinghouse F20T12-BB) and four broad spectrum (Verd-A-Ray F20T12-CC) lamps that produce blue radiation in excess of an array of eight conventional blue lamps, a spectrum closely approximating that of natural light, and at least 80% of the original blue radiation after 2,100 hours of use.


Intracellular deoxyribonucleic acid--modifying activity of intermittent phototherapy.

Phototherapy is capable of damaging the genetic material of eukaryotic and prokaryotic cells at fluences considerably less than that received by irradiated infants. It has been suggested that intermittent phototherapy, with varying on-off cycles, may offer theoretical advantages since the total light dosage received by the exposed infant is reduced. The present study was undertaken to determine the effect of intermittent phototherapy on the genetic material of human cells in tissue culture. Intermittent illumination produced more DNA damage than a similar light dosage administered continuously. These results suggest that intermittent phototherapy regimens may prove more deleterious to irradiated infants than continuous phototherapy.


The silent ductus arteriosus.

Preterm infants at risk of developing a patent ductus arteriosus were followed sequentially by physical examination, echocardiographic determinations of the LA/AO ratio, and chest roentgenograms. The results show that a significant number of infants who have no clinical signs or symptoms of a PDA have large left-to-right shunts. The presence of this shunt was suggested by acute increase in left atrial size by ECHO determination and confirmed by retrograde single-film aortography. Clinical signs and symptoms often developed several days after documentation of the left-to-right shunt.


Efficacy and safety of long-term phenobarbital therapy of familial cholestasis.

Two brothers with progressive familial intrahepatic cholestasis were followed during four years of phenobarbital therapy to assess its long-term safety and efficacy. Effects attributable to phenobarbital included sustained relief of pruritus, lowering of serum bilirubin levels, and enhanced hepatic excretion of 131I-rose bengal; serum bile acid levels were only transiently decreased. Two brief interruptions in therapy resulted in symptomatic deterioration. Phenobarbital did not retard growth nor impede the response to vitamin D therapy of concomitant rickets.


HbAlc--an indicator of diabetic control.

Hemoglobin Alc levels were determined on 16 nondiabetic and 115 diabetic subjects. Twelve of the diabetic patients were newly diagnosed and 12 were in the remission phase. The mean percentage of HbAlc in the nondiabetic subjects was 4.33 +/- 0.39 (SE), in those with long-standing diabetes 8.34 +/- 0.23 SE, in newly diagnosed diabetic patients 8.99 +/- 0.50 SE, and in those undergoing partial remission 5.16 +/- 0.18 SE. The mean HbAlc levels of these four groups differed significantly (0.001 less than P less than 0.025). Among the diabetic subjects there was a good correlation between HbAlc level and such measures as fasting blood sugar, urinary sugar, and degree of diabetic control, whereas the correlations between HbAlc and age, sex, or duration of the disease were not significant. The obtained data show that HbAlc measurement can serve as an objective measure of glucose control in diabetic subjects.


Indomethacin in the treatment of idiopathic minimal lesion nephrotic syndrome.

Ten patients with idiopathic minimal lesion nephrotic syndrome were treated with indomethacin. Nine patients received the drug for five weeks and one patient for nine weeks. Indomethacin was administered in a dose of 1 mg/kg/day during the first week and 2 mg/kg/day, thereafter. At the end of the study, nine patients remained edematous and all had a urinary protein excretion greater than 50 mg/kg/day, within the nephrotic range. Indomethacin did not change the course of the disease and its use in the treatment of IMLNS is not advised.


Home management of hyperkinetic children.

Six clinical programs and one controlled, experimental program are described in which parents of hyperkinetic children were trained to alleviate behavior problems in the home. Parents attended educational workshops in which basic general principles of behavior modification were taught. As a result of the training workshops, parents were able to achieve significant reductions in their children's hyperactivity and in the severity of behavioral problems, as well as significant gains in their knowledge of behavior management. All gains were maintained at the time of follow-up assessments. Parent-training workshops are considered to be a useful adjunct to other services provided to the hyperkinetic child and his family.


Sucrose malabsorption in children: noninvasive diagnosis by interval breath hydrogen determination.

To assess whether malabsorption of specific sugars is easily detected in a pediatric population by interval measurement of breath hydrogen excretion, hydrogen concentration was determined following administration of oral sucrose to six sucrose-intolerant children with congenital sucrase-isomaltase deficiency and in 16 sucrose-tolerant control subjects. Breath samples were collected by means of a newly  devised nasal prong technique not requiring active patient cooperation and suitable for use in all age groups. Breath hydrogen concentrations obtained by samples collected by this method correlated highly (r = 0.94) with the previously validated modified Haldane-Priestley tube method for sampling alveolar air. Identification of sucrose-intolerant individuals was achieved on the basis of hydrogen excretion: peak values, expressed as parts per million above baseline (deltappm), equalled 114 +/- 63 (mean +/- SD) versus 2.4 +/- 3.6 deltappm in control subjects (P = 0.007). Best discrimination between the groups occurred at 90 minutes postingestion. The findings validate this simple method for collection of expired air and demonstrate that breath hydrogen determination permits the noninvasive detection of sucrose malabsorption in children.


Incompetent lower esophageal sphincter and gastroesophageal reflux in recurrent acute pulmonary disease of infancy and childhood.

Fifteen patients with recurrent acute respiratory symptoms were evaluated for gastroesophageal reflux. All 15 had barium esophagrams. Ten of 15 had acid reflux tests performed and lower esophageal sphincter pressures measured. The data were compared to those in 23 patients with no acid reflux and 23 patients with positive acid reflux but no respiratory symptoms. Ten of ten patients with respiratory symptoms who were evaluated by the acid reflux test had positive results. The remaining five demonstrated GER by barium esophagram. LES pressure measurements in the ten patients were 11.3 +/- 1.5 mm Hg, which was significantly lower than the pressures in the acid reflux-negative group (20.3 +/- 1.3 mm Hg, P less than 0.001) but not different than in the patients with GER but no respiratory symptoms (13.9 +/- 1.5 mm Hg, P greater than 0.05). GER secondary to an incompetent lower esophageal sphincter may be one cause of recurrent acute respiratory disease in infants and children.


Interferon in nasal secretions from infants with viral respiratory tract infections.

Interferon levels in nasal secretions of infants under one year of age, and hospitalized with lower repiratory tract disease, were measured during two respiratory infection seasons. In the first year serial secretions from 50 infants with respiratory syncytial virus infection were examined. Undetectable or low levels of interferon were found in all samples, and mean levels did not fluctuate significantly in relation to disease and recovery. This was in contrast to anti-RSV IgA, which appeared and increased in concentration as virus shedding decreased and stopped. In the second year secretions were obtained from  nine infants with influenza A virus infection as well as from 13 with RSV. All those with influenza developed measurable interferon in secretions (geometric mean titer 138 units/ml), which was acid and heat stable, and trypsin sensitive (type I interferon). RSV infection again stimulated very low levels (geometric mean 5 units/ml). The lack of correlation of interferon concentration with cessation of RSV shedding suggests either that it is not involved in recovery or that low levels are adequate. On the other hand, it appears that the young infant is fully capable of a brisk local interferon response, at least to infection by influenza A.


Measles vaccination after exposure to natural measles.

When an extensive measles epidemic broke out in Turku in late 1975, the availability of a previous study on measles vaccination reactions in 442 children permitted a comparative evaluation to be made on reactions to and the efficacy of measles vaccine (Schwartz strain) administered after exposure to natural measles. In a preliminary study, nine children were vaccinated one to 14 days after exposure to natural measles but before prodromal symptoms appeared. Only one of these nine children developed symptoms and signs comparable to those of the natural disease. In five day-care centers the children were vaccinated when five or more children out of 30 to 40 at each center had measles. In only five of 74 exposed children were the signs and symptoms comparable to those of natural measles. No marked differences in signs and symptoms after the vaccinations were observed between the exposed and nonexposed children. It is concluded that vaccination is safe, can usually prevent measles, even when administered after a prolonged interval following exposure to natural disease, and can usually control an epidemic in progress.


Combined immunodeficiency disease associated with absence of cell-surface HLA-A and -B antigens.

An infant with a family history suggestive of immunodeficiency presented with combined immunodeficiency. No HLA-A and -B antigens were present on lymphocyte and platelet surfaces, but they were found in the serum. HLA-D determinants were present on lymphocytes. In spite of a fetal thymus transplantation, the infant died of infections associated with the immunodeficiency. The thymus and lymphoid organs were present but hypoplastic and contained few lymphocytes at postmortem examination. The finding of an immodeficiency associated with an absence of cell-surface HLA-A and -B antigens may be regarded as the consequence of the lack of cellular histocompatibility antigens on immune development. Alternatively, other membrane components may have also been defective and partly responsible for the observed abnormalities.


Thyroid antibodies in children and adolescents with thyroid disorders.

Thyroid antibodies were determined by three different techniques in the sera of 125 children and adolescents with thyroid disorders and in the sera of 53 short, normal children without thyroid dysfunction. The incidence of antithyroglobulin antibodies in patients with thyroiditis was highest when measured by radioimmunoassay (85%), less than when measured by hemagglutination (24%), and least by antimicrosomal antibodies (7%). No patient who had initially negative serum for RATA subsequently had positive tests during follow-up of five to 24 months, whereas eight of 31 patients with initially negative serum for ATA later developed positive tests. Treatment appeared to have a suppressive effect on RATA, but not on ATA titers, in hypothroid patients with clinical thyroiditis. The incidence of hypothyroidism in the patients with clinical thyroiditis on initial presentation was significant (37%) and suggests that identification of children and adolescents with thyroiditis is important to ensure adequate medical follow-up.


Geometric method for measuring body surface area: a height-weight formula validated in infants, children, and adults.

Estimates of body surface area were made based on measurement of 81 subjects, ranging from premature infants to adults. SA was calculated geometrically for each subject from 34 body measurements, and the values obtained compared with those based on previously published formulas and graphs. The most widely used formula, that of Du Bois and Du Bois, increasingly underestimated SA as values fell below 0.7 m2; the disparity was greatest in the newborn infant (7.96%). Closer agreement was obtained with the equations and nomograms of Body, Brody, Faber and Melcher, and Sendroy and Cecchini, although minor deviations were noted in some age ranges. The formula SA (m2) = weight (kg)0.5378 X height (cm)0.3964 X 0.024265, derived from the measured data by multiple regression analysis, gave a good fit for all values of SA from less than 0.2 m2 to greater than 2.0 m2 (r = 0.998). This formula was used to construct nomograms for estimation of SA in infants, children, and adults from height (length) and weight.


Cardiac catheterization in the neonate. A comparison of three techniques.

This study evaluated three methods of catheter entry for cardiac catheterization in neonates less than one week of age. Eighty-five neonates underwent venous catheterization through the umbilical vein, 77 by saphenous or femoral cutdown, and 31 by femoral percutaneous entry. Of these 194 neonates, 128 also had an aortic catheter introduced via the umbilical artery. Umbilical vein catheterizations took an average of 115 minutes, 30 minutes shorter than either of the other techniques. Fatal complications following catheterization occurred in 10 of the 194 neonates (5%) three of these were related to catheterization technique. Diagnostic cardiac catheterization and balloon atrial septostomy may be performed most quickly by way of the umbilical vessels. Percutaneous entry of the femoral vein in this series carried the lowest complication rate; cutdown entry resulted in the highest complication rate.


Nonoperative management of traumatized spleen in children: how and why.

In the absence of the apleen, overwhelming infection is a real threat. Therefore, there is a trend to try to preserve all spleens. Recognizing this, and realizing that not every damaged spleen must be removed, a nonoperative approach has been advocated and practiced for 35 yr at the Hospital for Sick Children in Toronto. This experience is recorded herein, providing indications and methods of management. The results are considered to be very satisfactory.


Splenic trauma--nonoperative management and long-term follow-up by scintiscan.

1972 TO April, 1977, 28 children with splenic rupture were managed nonoperatively. The diagnosis was confirmed by splenic scintigraphy with 99mTechnetium-sulfide colloid. Those patients whose condition was stable and satisfactory or maintained stable with intravenous fluids or blood transfusions were not operated upon. All patients sustained their ruptured spleens as a result of trauma, except for one spontaneous rupture in a patients with infectious mononucleosis. Emergency laparotomy for deterioration of clinical condition or late complications was never necessary. Splenic scans were repeated in 22 patients to assess resolution. Fourteen patients had minimal residual defects but there were no late complications detected.


Wandering spleen with torsion of pedicle in a child presenting as an intermittently-appearing abdominal mass.

Wandering spleen with torsion of the splenic pedicle is a rare condition with vague clinical manifestations. If this diagnosis is under condiseration, it can be established by angiography or by splenic scan.


Infarction of accessory spleen.

A rare disease that can mimic acute appendicitis is infarction of accessory spleen. It may occur in children and is difficult to diagnose preoperatively. Greater awareness of this entity may show not only that it is associated with other intraabdominal anomalies but also that it is more common in the tropics than elsewhere. Two cases are reported.


Splenic function following experimental dearterialization injury in the suckling rat.

An experimental splenic dearterilization injury was created in 1-wk-old rats to study the effect of vascular trauma on splenic function. Splenic weight significantly decreased 1 wk following injury but returned to control values within a month. Total splenic nuclear activity diminished initially but increased to above control values 1 mo after injury, and finally returned to normal at 2 mo. Survival rate after an intraperitoneal challenge with pneumococcus in groups 1 wk following total splenectomy and partial dearterlization was not significantly different than controls. This study confirmed the clinical impression that vascular injury to the spleen causes only a transient impariment of splenic size and function and provides further incentive to perform splenorrhaphy following splenic trauma.


Alternatives to total splenectomy: two case reports.

Postsplenectomy sepsis is a serious problem with high morbidity and high mortality. Surgical alternatives to total splenectomy are being sought. This paper describes two cases where, after splenectomy, some splenic tissue was either reimplanted or was left in situ and remains functional.


An attempt to separate xiphopagus twins sharing a common heart, liver, and duodenum.

An attempt was made to separate 7-wk-old conjoined twins. It proved unsuccessful because of extensive cardiac malformations in the shared heart. Details of operation and postmortem findings are described.


Pancreatitis in childhood.

Thirty cases of pancreatitis in children are reviewed. Diagnosis is based on the clinical findings of pancreatic inflammation, laboratory confirmation with elevated serum and/or urinary amylase values, and in some cases surgical or postmortem tissue substantiation. Four major classes of pancreatitis are defined in children: (1) traumatic; (2) systemic-disease associated; (3) drug-induced, caused by drug therapy for various life-threatening diseases, and (4) chronic pancreatitis, with or without an anatomic abnormality. If cases of traumatic pancreatitis are excluded, females outnumber males 5 to 1. A high index of suspicion is necessary to make the diagnosis, and this is very important if the mortality for pancreatitis in children is to be lowered. Awareness and consistent early aggressive intervention should increase the salvage rate.


The role of gastrin in congenital hypertrophic pyloric stenosis.

A study was designed and carried out to determine if the canine model of hypertrophic pyloric stenosis is applicable to other species and to demonstrate the transplacental passage of gastrin. Results of the study show that (1) pentagastrin does not induce hypertrophic pyloric stenosis in the rabbit; (2) human gastrin does not cross the canine placenta, and (3) gastrin has no documented and little inferred role in the etiology of CHPS.


Stage IVS neuroblastoma.

This is a review of the findings in 10 cases of stage IVS neuroblastoma, that have been observed in the First Surgical Department of Hokkaido University Hospital. The patients under the age of 1 yr in stage IVS neuroblastoma have a favorable prognosis; the survival rate was 70%. The regressions were histologically confirmed as maturation of the neuroblastoma cells to ganglioma cells. The lymphocyte counts and T-cell function were well maintained in the surviving patients but both were markedly reduced in the patients who later died. The treatment should be conservative so that immune mechanisms are not inhibited and should be withheld until respiratory failure or progressive signs toward stage IV are identified.


Appendicitis in infancy.

One percent (40 infants) of all the children treated for acute appendicitis at Our Lady's Hospital for Sick Children presented during the first 2 yr of life. Nineteen of the 40 children had an appendix mass at the time of the diagnosis. Conservative management of the appendix mass followed by delayed elective appendectomy is a safe and effective method of treatment.


Intestinal obstruction from appendiceal abscess in a newborn infant.

Perforated appendix in the newborn period is rare, its symptoms are occult and its outcome is disastrous. Associated mechanical small bowel obstruction as part of the clinical picture is rare indeed. We have treated a premature infant who presented with prolonged intermittent vomiting. Factors contributing to difficulty in diagnosis and to eventual succussful management are discussed.


Neonatal appendicitis: ischemic infarction in incarcerated inguinal hernia.

A premature 12-day-old infant with ischemic infarction of the appendix due to hernial incarceration is presented. Literature review (1901-1975) of 106 cases of acute appendicitis in the first 30 days of life permitted tabulation of some clinical aspects in 94 cases. Overt manifestations mandating surgical intervention and isolation of the inflammatory process in the inguinoscrotal region are important factors responsible for the significantly better prognosis for neonatal hernial versus intraabdominal appendicitis.


Acute appendicitis located in a scrotal hernia of a premature infant.

A premature infant is presented with acute appendicitis in a scrotal hernia causing localization of the inflammatory signs to the scrotum, and relatively early operation.


Hepatic mesenchymal hamartoma causing heart failure in the neonate.

This is the first report of an hepatic mesenchymal hamartoma causing congestive heart failure in an infant. These benign tumors usually present as a bulky abdominal mass but rarely can present with congestive failure when the angiomatous component is prominent.


A triple duplication of the alimentary tract.

Duplications of the alimentary tract occur infrequently, and are usually isolated anomalies. In the infant described below, a complex clinical picture was the result of three distinct duplication in widely separated portions of the alimentary tract (esophagus, duodenum, ileum). Details of the clinical course and technical management of an extremely long ileal duplication form the basis for this report.


Actinomycotic bowel and ureteral obstruction in a patient with Hodgkin's disease.

This is a case report of a patient who presented with colonic and ureteral obstruction 4 yr following diagnosis and abdominal-pelvic radiation therapy of stage IIA Hodgkin's disease. Biopsy of a pelvic mass revealed actinomycosis.


Torsion of the normal uterine adnexa in premenarchal girls.

Two cases are reported of torsion of the normal uterine adnexa in premenarchal girls. In one patient, aged 3 yr, both the ovary and fallopian tube had undergone torsion. The second patient, aged 11 yr, had sustained torsion of the fallopian tube alone. This is the first reported case of torsion of the fallopian tube occurring without torsion of the ovary in a patient in this age group. The mechanisms of torsion of normal uterine adnexa are described and the operative management is discussed.


Friendship, proximity, and self-disclosure.

Patterns of self-disclosure were explored by means of a questionnaire administered to pairs of roommates and hallmates (non-roommates living on the same floor) in freshman dormitories. It was predicted and found that friendship was more highly related to self-disclosure in intimate than in non-intimate topic areas, whereas proximity was more highly related to disclosure in non-intimate than in intimate areas. It was also found that friendship and intimate disclosure were more highly related among women than among men. These findings emphasize the interplay of personal, role-related, and environmental factors which underlie patterns of friendship and self-disclosure. They also point to the importance of viewing self-disclosure in differentiated terms, rather than as single monolithic entity. Other findings of both substantive and methodological interest are reported. For example, there was a strong tendency for respondents to overemphasize the degree to which their patterns of giving and receiving personal information were symmetrical. There was also a tendency for respondents to report giving more disclosure than they received in non-intimate areas, but not in intimate areas.


Objective self-awareness and individuation: an empirical link.

An experiment was conducted to determine whether the phenomenal experiences associated with the states of objective and subjective self-awareness are those which typically are associated with the states of individuation and deindividuation. In order to test this hypothesis, 20 male and 20 female matched pairs of subjects completed 15 self-descriptive statements on a Who Am I questionnaire under conditions of experimentally manipulated self-awareness (high vs. low). The obtained responses were then coded on 21 dimensions of self-conception, including several suggested by Gordon (1968). Converging result from a number of different measures indicated that increased objective self-awareness led to a more individuated conception of self. More specifically, objective self-awareness appeared to increase responding on dimensions which reflect individuation but to decrease responding on dimensions which reflect deindividuation suggested that this effect held strongly for low self-monitoring subjects. The self-descriptions of high self-monitoring subjects, however, appeared to be relatively unaffected by situationally induced self-awareness.


Direct and vicarious censure in the control of interracial aggression.

An experimental explored the relative effectiveness of two strategies for controlling interracial aggression: observing other individuals censured for aggression and potential direct censure of the aggressor himself. Subjects were provided with an opportunity to agress under conditions designed to maximize or reduce each type of censure. A principal components analysis of the data revealed two orthogonal variates: direct aggression and indirect aggression. It was found that both observed censure and potential direct censure were effective in modifying directly aggressive responses. However, these forms of censure interacted in their effect on indirect aggression, such that observed censure was effective in reducing indirect aggression only under conditions of potential direct censure.


Who cares about ecology? Personality and sex differences in environmental concern.

This study was designed to identify personality factors that underlie concern for ecological-environmental problems. High and low environmental-concern individuals were given the California Psychological Inventory and were found to differ significantly on many subscales. A factor analysis of the CPI data produced four factors which closely paralleled previous CPI research findings. In conjunction with this analysis, four factorially derived scores were obtained for each individual. Comparison of high and low environmental-concern individual's factorially derived scores showed high environmental-concern persons as having stronger value orientation, person orientation, and ethical-conscientiousness, but not differing from low environmental-concern individuals in terms of independence of thought or action. Further, high environmental-concern females were found to be significantly more extraverted, "leader-types" than low environmental-concern females; while the opposite relation was obtained for males. Thus, it appears that men and women become involved with the environmental movement for different reasons, Finally, additional implications of the involvement of basic psychological individual differences in determining ecological-environmental concern were discussed.


Physical/verbal aggression: sex differences in style.

Two studies exploring the use of physical/verbal aggression are reported, the first using women and the second using men as subjects. Both studies allowed subjects to choose between and control the intensity of two response modes: verbal aggression (insults) and physical aggression (electric shock). Aggressive style was investigated over two levels of arousal, sex of experimenter, and sex of provocateur-victim. Results indicated that women aggressed discriminatively in the verbal mode as a function of their arousal, while men were capable of aggressing discriminatively in both the verbal and physical modes. Men who had been disagreed with and punished by a female victim-provocateur in the presence of a male experimenter or by a male victim in the presence of a male experimenter demonstrated high levels of physical aggression compared to the other groups.


Effects of personality and situational variation in locus of control on cheating: determinants of the "congruence effect".

Thirty-two male and 32 female introductory psychology students were given the opportunity to falsely report success (i.e., to cheat) on a series of objectively unsolvable achievement tasks. Consistent with previous evidence, a Personality X Situational Locus of Control interaction effect, accounting for 24% of the variance, was found whereby persons classified as having generalized internal locus of control beliefs (internals) cheated more when the task was described as requiring skill while those with external control beliefs (externals) cheated more when chance presumably determined performance outcomes. Differing rates of task persistence, postperformance belief and affect ratings. and stated reasons for cheating (or not) were consistent with both affective and cognitive theories in explaining the cheating to conform to their status on the internal stable dimension of ability, externals were concerned with maintaining a belief in their status as fortunate individuals, also conceived as an internal stable attributional determinant. No sex differences in cheating or persistence behavior were found.


Depression and causal attributions for success and failure.

The present study investigated the effects of depression on causal attributions for success and failure. Specifically, female university students were separated into depressed and nondepressed groups on the basis of Costello--Comrey Depression Scale scores, and then received either 20%, 55%, or 80% reinforcement on a word association task. Following the task, attributions were made for outcome using the four factors of effort, ability, task difficulty, and luck. In accord with predictions generated from a self-serving biases hypothesis, nondepressives made internal (ability, effort) attributions for a successful outcome (80% reinforcement) and external attributions (luck, task difficulty) for a failure outcome (20% reinforcement). As predicted from consideration of the self-blame component of depression, the attributions made by depressives for a failure outcome were personal or internal. Contrary to expectations, depressives also made internal attributions for a successful outcome. The findings for depressives were discussed in relation to the recently revised learned helplessness model of depression, which incorporates causal attributions. For nondepressives, the findings were considered in terms of the self-serving biases hypothesis.


The bogus pipeline as lie detector: two validity studies.

The validity of the bogus pipeline procedure for eliciting truthful responses from subjects in social psychological experiments was tested in two studies. Subjects were illegitimately informed about how to perform well on an experimental test, were tested, and then were asked whether they had possessed this prior information. As compared to subjects responding to pencil-and-paper questions or face-to-face questionning by the experimenter, those in a bogus pipeline condition confessed more often.


Modeling processes in the acquisition of fears: vicarious electrodermal conditioning to fear-relevant stimuli.

Fear-relevant (snakes, spiders, and rats) and fear-irrelevant (flowers, mushrooms, and berries) pictures were compared as conditioned and instigating stimuli in a vicarious classical conditioning paradigm with skin conductance responses as the dependent variable. A female confederate model and subject watched the pictures side by side. A female stimulus presentations, the experimenter interrupted to investigate alleged overreactions of the model to one of the stimulus classes. The model then vividly described a phobia for this object, which was to serve as a vicarious instigating stimulus. The experiment continued for a few conditioning trials, and then the experimenter announced that the disturbing stimulus would be omitted before the second part of the experiment. There was no effect of stimulus content on vicariously instigated responses, although significant overall instigation was observed. However, the responses to the stimulus that was paired with the model's phobic stimulus, that is, the vicariously conditioned responses, failed to extinguish during the second part of the experiment when it was fear-relevant but extinguished immediately when it was fear-irrelevant.


Ambient temperature and the occurrence of collective violence: the "long, hot summer" revisited.

Archival data pertaining to 102 instances of serious collective violence were examined in order to study the relationship between ambient temperature and the occurrence of such events. Results indicated that the frequency of collective violence and ambient temperature were curvilinearly related. Specifically, ambient temperature was directly associated with the frequency of collective violence through the mid-80s (degrees Fahrenheit). Beyond this point, however, further increments in temperature were associated with a decreasing incidence of such events. Additional findings indicated that ambient temperature increased significantly during the 7 days preceding the outbreak of collective violence, remained stable during its occurrence, but then decreased significantly in the 3 days following its termination. Possible implications of these findings, as well as their relationship to the results of previous laboratory studies, are discussed.


Drug choice as a self-handicapping strategy in response to noncontingent success.

In two closely related experiments, college student subjects were instructed to choose between a drug that allegedly interfered with performance and a drug that allegedly enhanced performance. This choice was the main dependent measure of the experiment. The drug choice intervened between work on soluble or insoluble problems and a promised retest on similar problems. In Experiment 1, all subjects received success feedback after their initial problem-solving attempts, thus creating one condition in which the success appeared to be accidental (noncontingent on performance) and one in which the success appeared to be contingent on appropriate knowledge. Males in the noncontingent-success condition were alone in preferring the performance-inhibiting drug, presumably because they wished to externalize probable failure on the retest. The predicted effect, however, did not hold for female subjects. Experiment 2 replicated the unique preference shown by males after noncontingent success and showed the critical importance of success feedback.


Characteristics and tachyphylaxis of gastrin-stimulated gastric acid secretion in the cat.

1. The characteristics of gastrin-stimulated gastric acid secretion were investigated in conscious cats fitted with chronic cannulated gastric fistulae, with particular reference to tachyphylaxis. 2. There is a significant postive correlation between the peak acid secretion in response to pentagastrin 8 microgram kg-1 hr-1 and body weight. Male cats secret significantly greater amounts of acid in response to pentagastrin than females. The difference is lessened, but not eliminated, by expressing the acid out put in terms of body weight. 3. Pentagastrin stimulates a dose-dependent increase in acid secretion in the range 0.5-32 microgram kg-1 hr-1 when the response to each dose is assayed on separate occasions. Pentagastrin 64 microgram kg-1 hr-1 does not produce a further increase in acid secretion. The acid response to pentagastrin 1-16 microgram kg-1 hr-1 assayed on a single occasion by a continuous infusion method shows a dose-response relationship up to 8 microgram kg-1 hr-1 when it reaches a plateau of secretion. There is no difference between the two methods of assaying the gastric acid stimulating activity using doses of pentagastrin up to 8 microgram kg-1 hr-1. 4 The acid secretion in response to pentagastrin 8 microgram kg-1 hr-1 reaches a maximum after 45 min of stimulation and thereafter shows tachyphylaxis. Over a period of 5 hr there are at least two phases of tachyphylaxis distinguishable. During the period 0.75--2.5 hr of stimulation there is a fast phase of tachyphylaxis (-32.0 muequivH+kg-1 15 min-1). This is followed by a slow phase of tachyphylaxis (-9.4 muequivH+kg-1 15 min-1) up to 5 hr of stimulation. 5. The absolute rate of the fast phase of tachyphylaxis of acid secretion (muequivH+kg-1 15 min-1) increases with increasing doses of pentagastrin, but rates of tachyphylaxis are similar when expressed as a percentage of the peak acid response to the particular dose of pentagastrin (5.1--7.8% 15 min-1). Synthetic human gastrin-17, the synthetic C-terminal decapeptide of human gastrin and the C-terminal tetrapeptide of gastrin have comparable rates of tachyphylaxis. The possible receptor models for the tachyphylaxis of gastrin-stimulated acid secretion are discussed.


Uptake and binding of calcium by axoplasm isolated from giant axons of Loligo and Myxicola.

1. Axoplasm isolated from giant axons of the squid Loligo and of the polychaete worm Myxicola continues to bind Ca and maintain an ionized Ca concentration close to 0.1 microgram which is similar to that seen in intact axons. 2. Injection of Ca into isolated axoplasm only produces a transient rise in ionized Ca showing that axoplasm can buffer a Ca challenge. 3. In order to characterize the Ca-binding systems isolated axoplasm was placed in small dialysis tubes and exposed to a variety of artificial axoplasms containing 45Ca. 4. In the presence of ATP, orthophosphate and succinate, Ca uptake appreciable and after 4 hr exposure of Loligo axoplasm to 0.1 microgram-Ca, approximately 100 mumole Ca/kg axoplasm was bound. Binding could be divided operationally into two distinct processes, one that requires ATP or succinate togeth with orthophosphate and is blocked by cyanide and oligomyocin, and one that is unaffected by these reagents. 5. Energy-dependent binding has a large capacity, but a rather low affinity for Ca, being half-maximal between 20 and 60 microgram-Ca. In Loligo, its properties closely parallel those of a crude mitochondrial preparation isolated from axoplasm; but there are some interesting differences in Myxicola. Energy-independent binding is half-maximal at ionized Ca concentrations between 80 and 160 nM but is readily saturated and has a capacity of 6-60 mumole/kg axoplasm. 6. Ca binding by Loligo is greatest in media containing roughly physiological concentrations of K and is reduced by isosmotic replacement of K by Na. This effect seems to be confined to the energy-dependent, presumed mitochondrial, component of binding. 7. Ca binding by Loligo axoplasm is reduced by both La and Mn ions.


Blocking of the squid axon potassium channel by external caesium ions.

1. The blocking by external Cs of inward tail currents though the K channel of the squid giant axon, as seen by the effect of Cs on the 'instantaneous' I-V curve is described. 2. Block onset is complete within 50--100 musec of a step in voltage. The block produces a negative slope region in the inward current quadrants of the I-V plots. 3. The experiments were performed in the presence of external concentrations of 240 mM-K and 0-200 mM-Cs, with the external ionic strength maintained by substituting Tris or Na for the Cs. Essentially the same results were obtained with either Tris or Na as the substitute ion. 4. The concentration of Cs required to block 50% of the K channels at zero transmembrane voltage, in intact axons, was estimated to be approximately 1 M. 5. The slope of the dose-response curve is steeper than expected for a blocking reaction with 1:1 stoichiometry when membrane voltage is in the neighbourhood of 100 mV. 6. With Cs concentrations greater than or approximately 50 mM, the voltage dependence of the block is too steep to be accounted for by the binding of a single Cs ion per channel within the membrane electric field. 7. In perfused axons, the block occurred at less negative internal voltage when internal K concentration was reduced. 8. These observations are qualitatively consistent with a multisite channel showing single file properties.


Glutamate sensitivity and distribution of receptors along normal and denervated locust muscle fibres.

1. Factors influencing the glutamate sensitivity of extrajunctional regions of innervated and denervated locust muscle fibres have been investigated. Properties of the two types of extrajunctional glutamate receptors, D- and H-receptors, have been studied in regions of high and low sensitivity. 2. The low level of extrajunctional sensitivity which is normally present in innervated fibres was 20-30 times higher at the muscle-tendon junction than at other sites; increased sensitivity extended about 20-40 micron from the tendon. After denervation or localized damage the entire extrajunctional sensitivity was increased approximately 100 times above control levels. 3. Applying L-glutamate (which activates D- and H-receptors) and DL-ibotenate (which activates H-receptors) from multibarrelled micropipettes showed that increased extrajunctional sensitivity resulted from an increase in D-receptors while H-receptors were apparently unchanged. 4. Coulomb dose vs. response relationships for the action of glutamate on D-receptors were similar when obtained at the muscle-tendon junction and nerve-muscle junction of innervated fibres or at extrajunctional regions in denervated fibres. 5. Time course of onset and percentage desensitization of D- and H-receptors in innervated fibres were similar. The percentage desensitization of D-receptors in extrajunctional regions of high sensitivity was greatly reduced. 6. It is suggested that D- and H-receptors are independent and that the trigger for increased receptor sensitivity acts specifically on D-receptors. In all respects so far studied, the D-receptors resemble extrajunctional ACh-receptors in vertebrate muscle.


Effects of membrane potential and temperature on the excitatory post-synaptic current in the crayfish muscle.

1. Effects of membrane potential and temperature on the excitatory post-synaptic current (e.p.s.c.) were studied in the voltage-clamped crayfish muscle. E.p.c. was recorded either by measuring the feedback current through an intracellular wire electrode or by focal recording with an extracellular micro-electrode. 2. The amplitude of the e.p.s.c. obtained by the voltage clamp method varied almost linearly with membrane potential between -100 mV and +70 mV, whilst the reversal potential was +23.8 +/- 3.9 mV (S.E. of mean). 3. The declining phase of the extracellular e.p.s.c. was slightly prolonged by depolarization and shortened by hyperpolarization. Potential dependence of the decay time constant was expressed by tau = a exp (AV), with a = 2.78 msec and A = 0.0037 mV-1. 4. The decay time constant had a Q10 of 2.3 and the growth time had a Q10 of 1.5. 5. The voltage dependence of the decay phase of the e.p.s. was the reverse of that found in frog end-plate. It is concluded that the voltage dependence of the time course is not related either to the charge of ions which carry the synaptic current or to the charge of the transmitter.


Adaptive rundown of excitatory post-synaptic potentials at synapses between hair cells and eight nerve fibres in the goldfish.

1. The excitatory post-synaptic potentials (e.p.s.p.s.) evoked by sound stimuli were recorded intracellularly from large afferent eight nerve fibres in the sacculus of the goldfish (S1 fibres). The fish were anaesthetized with MS-222 and spike potentials were suppressed with locally applied tetrodotoxin. 2. The e.p.s.p.s. successively evoked in response to each wound wave showed a marked rundown in size, while no reduction was observed in the microphonic potentials. The amplitude of successive e.p.s.p.s was reduced keeping approximately a fixed ratio to the preceding ones, suggesting that the rundown is attributable to a depletion of transmitter quanta from the release sites. 3. The rate of rundown of successive e.p.s.p.s, however, remained almost unchanged when the intensity of the stimulus sound was changed. It was also observed that, even after the e.p.s.p.s had been completely adapted to a continuous sound, a vigorous discharge of new e.p.s.p.s was observed when the intensity of the sound was increased. 4. These findings seem to indicate that it is the size of the readily available store and not the release fraction that is changed by a change in the sound intensity. 5. The saccular macula was superfused with solutions different in Ca and Mg ion concentrations. High Ca ion concentration brought about an increase in the size of the readily available store as well as the release fraction. 6. Mechanisms underlying these observations were discussed in terms of the quantal release mechanism as well as the morphology of the release sites.


New properties of rabbit retinal ganglion cells.

1. Receptive fields of centre surround cells in the rabbit retina were investigated. There is a clear distinction between cells with sluggish responses, low spontaneous activity and slow conduction velocity (centre surround sluggish cells) and cells with brisk responses, higher spontaneous activity and faster conduction velocity (X and Y cells). The sluggish cells can be divided into sustained and transient types. X and Y cells can be distinguished from each other by their responses to a moving linear grating, a large rapidly moving object and whether or not there is a response to the alternation of certain stimuli. Some times the response to a rotating radial grating, the rate of spontaneous activity, and whether or not the response to spots and annuli was sustained or transient could also be used to distinguish these two types. The antidromic latency from electrical stimulation of the optic chiasm and the periphery effect did not distinguish X from Y. 2. Eleven colour coded units were investigated. They all gave on responses to blue light in the centre of their receptive field and off responses to green light in the periphery of their receptive field. The blue pigment had a spectral sensitivity peaking at about 465 nm. The other pigment peaked near 500 nm, like the rods but gave a response at high mesopic and probably photopic levels. In some cases there was evidence for excitatory input from the green receptors to the centre of the receptive field. All the colour coded cells had rapidly conducting axons and were on centre X cells by all criteria. 3. Eighty-five cells various types other than colour coded were tested for their thresholds at 420 nm and 590 nm. In all cases the results were explained by a pigment peaking close to 500 nm, even at high mesopic and low photopic levels, which suggests the existence of cones with a cyan pigment in them. 4. Conduction latency from stimulation at the optic chiasm was measured for cells with centre surround receptive fields and cells with more complex receptive fields. Both 'on-off' and 'on' directionally sensitive cells have short conduction latencies, overlapping X and Y cells. Orientation selective cells and local edge detectors have long conduction latencies, overlapping centre surround sluggish cells. The sample of uniformity detectors was too small to characterize...


Effects of picrotoxin and strychnine on rabbit retinal ganglion cells: lateral interactions for cells with more complex receptive fields.

1. The effects of picrotoxin and strychnine were tested on the receptive fields of direction sensitive cells, orientation sensitive cells, local edge detectors, uniformity detectors and large field units in the rabbit retina. 2. Picrotoxin eliminated the direction specificity and size specificity of 'on-off' and 'on' directionally sensitive cells for both black and white objects. Picrotoxin also made 'on' directionally sensitive cells responsive to faster velocities. 3. Picrotoxin eliminated the orientation specificity of orientation sensitive cells, and changed the bar-flank arrangement of the receptive field into a centre surround arrangement. Thus, the orientation specificity is due to inhibitory rather than excitatory mechanisms. 4. Picrotoxin altered the speed sensitivity of large field units so that they responded to slow speeds as well as fast ones, like centre surround Y cells. 5. Strychnine abolished the size specificity of local edge detectors and changed their speed specificity so that they responded to faster speeds. 6. Picrotoxin changed a uniformity detector into a sustained on centre cell. 7. Strychnine did not effect the direction specificity of directionally sensitive cells, the orientation specificity of orientation sensitive cells, or the speed specificity of large field units. Picrotoxin did not affect the size specificity of local edge detectors. 8. Picrotoxin and strychnine usually had opposing effects on the transient responses of these units to spots and annuli. In general picrotoxin prolonged and enhanced these responses at both on and off, and strychnine shortened them. 9. The effect of these drugs for every type of ganglion cell with complex receptive field properties was to make the receptive field more simple. The orientation selective cells, large field cells, 'on' direction selective cells and uniformity detectors seem to be centre surround cells with special properties that are abolished by these drugs. The 'on-off' direction selective cells and local edge detectors still on-off receptive fields, but in each case one of the drugs abolished the feature that was the basis for the cell's name.


Effects of picrotoxin and strychnine on rabbit retinal ganglion cells: changes in centre surround receptive fields.

1. The effects of picrotoxin and strychnine on the centre surround types of ganglion cell (X, Y, sluggish sustained and sluggish transient with on or off centres, and colour coded) were studied in the rabbit retina. 2. Picrotoxin changed the centre surround balance in favour of the centre for Y cells and sluggish transient cells but not for X cells or sluggish sustained cells. 3. Inhibition by a moving radial grating was abolished by picrotoxin for off centre Y cells, but not for on centre Y cells. 4. Picrotoxin abolished the surround response for six on centre sustained cells. These were hybrid cells with conduction velocities and receptive field properties characteristic of more than one of the X, Y and sluggish categories. The surround was not abolished by picrotoxin for any of the cells which fell in the standard X, Y and sluggish categories. 5. Strychnine did not affect the centre surround balance substantially in any of the cells tested. Strychnine did effect the transients: in general strychnine shortened or abolished them, while picrotoxin made them larger.


Effects of diethylstilboestrol and ovarian steroids on the contractile responses and calcium movements in rat uterine smooth muscle.

1. The synthetic oestrogen diethylstilboestrol had a potent inhibitory effect on the mechanical responses of the rat uterus. The spontaneous contractions were reduced in amplitude by 2 microgram and were completely abolished by 20 microgram diethylstilboestrol. The amplitude of contractions induced by acetylcholine (ACh) was also considerably reduced in the presence of 20 microgram of the compound. 2. Oestradiol (oestradiol-17 beta) had a weaker, and progesterone a negligible, effect on the spontaneous contractions. 3. In the depolarized (induced by high potassium) uterus, the log concentration response curve for contraction induced by Ca was sigmoidal and reached its maximum at about 1 mM-Ca. These responses to Ca were greatly depressed by oestradiol and progesterone and were again completely abolished by diethylstilboestrol. All three compounds were also able to induce a relatively rapid relaxation in preparations contracted by Ca. 4. Inhibition of the ACh contraction in the depolarized uterus by diethylstilboestrol, oestradiol and progesterone had the characteristic of blocking the second, and relatively slow, phase of the contraction without influencing the first rapid response. A similar pattern of inhibition was observed in the presence of D-600 or EGTA. 5. The lanthanum method gave only an approximate measure of cellular Ca in the rat uterus, since La failed to block 45Ca efflux and was unable effectively to displace extracellular 45Ca. 6. Diethylstilboestrol reduced the influx of 45Ca both in normal and depolarizing media but did not affect 45Ca efflux. 7. These results indicate that oestrogens and progesterone are able to decrease Ca entry into the uterine cells, which probably accounts for their inhibitory effect on the contractile activity. The mechanism by which these agents induce relaxation of a contracted uterus also seems to depend on the inhibition of Ca influx.


Long-term potentiation and depression of synaptic responses in the rat hippocampus: localization and frequency dependency.

1. The consequences of repetitive activation of excitatory synaptic inputs to the CA1 pyramidal cells of rat hippocampus have been studied using in vitro techniques. 2. Single stimulation trains of 100 pulses at rates of 5-100/sec resulted in potentiation of population spike amplitudes lasting the duration of a 5 min test period in thirty-four out of thirty-five cases. Trains of 100 pulses delivered at 1/sec resulted in depression of the stimulated pathway in ten out of twelve experiments. 3. Responses to test stimulation of other excitatory inputs to the same cell population were depressed following conditioning trains at frequencies in the range 1-100/sec. Depression was seen both in the population spike amplitude (reflecting synchronous cell discharge) as well as the extracellularly recorded population e.p.s.p., and appeared to be maximal at lower frequencies. 4. Trains of antidromic stimulation of the CA1 cell population produced subsequent decreases in synaptically evoked responses, indicating that repetitive firing of pyramidal neurones or interneurones do not cause potentiation, but may be involved in heterosynaptic depression. 5. The results suggest that potentiation and heterosynaptic depression arise from different mechanisms, and that potentiation is confined to the set of terminals activated by a conditioning train, whereas the depression is generalized to the whole neurone.


Inhibition of baroreceptor and chemoreceptor reflexes on heart rate by afferents from the lungs.

1. Brief stimuli were delivered to the carotid baroreceptors or chemoreceptors in dogs anaesthetized with chloralose and paralysed with D-turbocurarine. Baroreceptor stimulation was achieved by forceful retrograde injection of 2-5 ml or air-equilibrated saline into the external carotid artery after first clamping the common carotid artery. Chemoreceptor stimulation was achieved by rapid retrograde injections of 0.2-0.5 ml of warmed CO2-equilibrated saline into the external carotid artery. Observations were made during periods of temporary cessation of artificial ventilation. 2. When the volume of the lungs was not changing, prompt decreases in heart rate  were evoked by chemoreceptor or baroreceptor stimuli except when these were delivered during the inspiratory phase of breathing (as judged from the records of phrenic nerve activity). 3. No changes in heart rate were evoked when these stimuli were timed to occur during expansion of the lungs in response to a rapid increase in intratracheal pressure (6-10 mmHg in 1-2 sec). Decreases in heart rate were evoked when the stimuli occurred during slower inflations of the lungs. 4. Both stimuli regained their effectiveness on heart rate with time after inflations of the lung when the lungs were held inflated. Both stimuli evoked large decreases in heart rate when delivered during deflations of the lung. 5. The effects of lung inflation on the effectiveness of both cardiodepressor reflexes were abolished by surgical denervation of the lungs.


Reflex bradycardia occurring in response to diving, nasopharyngeal stimulation and ocular pressure, and its modification by respiration and swallowing.

1. Digital pressure applied to the eyes evokes reflex bradycardia in human subjects and anaesthetized dogs. The bradycardia is most pronounced when breathing stops. 2. In the dog oculo-cardiac reflex bradycardia is mediated by vegal stimulation and by sympathetic withdrawal. 3. Oculo-cardiac reflex bradycardia in the dog is reduced by central neural inspiratory activity and by the excitation of pulmonary afferents by inflation of the lungs. In human subjects it is reduced when inspiratory efforts are made against a closed glottis. 4. Nasopharyngeal stimulation with water evokes reflex bradycardia in the anaesthetized dog. This bradycardia is reduced by central neural inspiratory activity and by the excitation of pulmonary afferents by inflation of the lungs. 5. Bradycardia occurs in normal human subjects during immersion of the face in water ('diving'). This bradycardia is reduced when inspiratory efforts are made against a closed glottis. 6. Swallowing evokes transient tachycardia in human subjects. During diving or the application of ocular pressure, swallowing reduces the reflex bradycardia which these evoke.


Renin substrate in plasma of unanaesthetized pregnant ewes and their foetal lambs.

1. In unanaesthetized preparations 6-14 days after catheterization, the concentration of renin substrate (AI 212 +/- 20 ng/ml. S.E. of mean) in the plasma of foetal lambs during the last third of gestation was significantly less than that of paired samples of maternal plasma (AI 350 +/- 27 ng/ml.). 2. During the first 5 days following catheterization the concentration of renin substrate in maternal plasma was lower than subsequently but was raised if the uterus contained a nephrectomized foetus. 3. The concentration of renin substrate in the plasma of intact foetal lambs without nephrectomized twins varied little in the post-catheterization period and later; the concentration of substrate in nephrectomized foetal lambs averaged threefold that of intact lambs and a similar concentration of substrate was found in intact twins of such lambs in the immediate post-catheterization period. 4. It is suggested that the ratio of foetal/maternal plasma renin activity understates their relative enzyme activity since foetal substrate concentration is so considerably less than maternal.


Drinking and haemodynamic changes induced in the dog by intracranial injection of components of the renin-angiotensin system.

1. Intracranial injections of the individual components of the renin-angiotensin system caused drinking in water-replete dogs. 2. Angiotensin II was the most reliable, potent and rapidly acting intracranial dipsogen and elicited drinking in the absence of peripheral circulatory changes. After the highest dose of angiotensin II (10(-9) mole) five dogs drank a mean amount of 380.0 +/- 88.6 ml. For the other components, the order of dipsogenic effectiveness was angiotensin I, synthetic renin substrate, and angiotensin III. 3. Isotonic saline, bradykinin (10(-10) mole), eledosin-hexapeptide (10(-10) mole), oxytocin (10(-10) mole) and prostaglandin F2alpha (1-200 X 10(-12) mole) were ineffective. 4. Intracranial renin (10 m-u.) produced a mean intake of 445 +/- 152 ml. of water in eight dogs. 5. Dog renin substrate and synthetic renin substrate, injected intracranially in a dose of 10(-10) mole, produced similar intakes of water but these amounts were very much less than the volume drunk in response to the same dose of angiotensin II. 6. None of the components injected into dipsogenically responsive sites in the brain caused changes in blood pressure, although the act of drinking itself produced a small rise. 7. Angiotensin II at the highest dose produced drinking when injected into the subfornical organ, preoptic region, anterior hypothalamus, lateral ventricle, third ventricle, ventral hippocampus and mid-line thalamus. Negative sites were found in the caudate nucleus, fourth ventricle, mid-brain, posterior thalamus, dorsal hippocampus, lateral hypothalamus and posterior hypothalamus. 8. After the lowest dose of intracranial angiotensin II (10(-12) mole) only the preoptic region and subfornical orgal were responsive. These two sites were equally sensitive in terms of latency and amounts drunk at all doses injected. 9. Angiotensin did not necessarily have to reach a cerebral ventricle in order to cause drinking. 10. The dog resembles the rat in its responsiveness to the dipsogenic action of intracranial angiotensin II. The regions of the brain from which drinking can be elicited are more widespread than has been claimed by some in the rat.


Systemic angiotensin-induced drinking in the dog: a physiological phenomenon.

1. Intravenous infusion of the individual components of the renin-angiotensin system caused drinking in dogs in water balance. 2. Angiotensin II was the most potent and rapidly acting peptide inducing drinking. The minimum effective rate of infusion was between 8.3 and 16.6 X 10(-12) mole kg-1 min-1 which yield blood levels of angiotensin II that fell well within physiological limits for the dog and were mildly pressor. Angiotensin I and synthetic renin substrate caused less drinking than angiotensin II, and angiotensin III was the least effective dipsogen. 3. Renin caused significant drinking when infused I.V. at a rate of 0.5 u. min-1 for 15 min. Drinking was slower in onset and continued for longer than after other components of the renin-angiotensin system. 4. Within the dose range 1875-15,000 X 10(-12) mole of angiotensin II the amount of water drunk depended more on the rate of infusion than on the duration of the infusion. 5. During an I.V. infusion of angiotensin II lasting 2 hr, the rate of drinking was greatest during the first 15 min. After this declined progressively. 6. A delay of 1 hr after the start of an intravenous infusion of angiotensin II before access to water was allowed, did not significantly reduce the amount of water drunk. Nor did infusion of isotonic saline for 105 min reduce drinking in response to a subsequent infusion of angiotensin II. However, a preload of dilute milk approximately equal in volume to the amount of water normally drunk in response to I.V. angiotensin II significantly reduced drinking. Therefore the dog stopped drinking during long-term infusions of angiotensin II owing to the action of satiety mechanisms and not to tachyphylaxis or fatigue. 7. Intracarotid infusion of angiotensin II, angiotensin I, synthetic renin substrate and angiotensin III, at 40 X 10(-12) mole min-1 also caused drinking. Intakes of water were similar to the intakes after I.V. infusion at six times the arterial rate, except that angiotensin I was relatively less effective by intracarotid infusion than by I.V. infusion. 8. Renin, infused at 0.5 u. min-1 for 15 min, was much less effective by intracarotid infusion than by intravenous. 9. These results are compatible with a role for circulating angiotensin II in the thirst of hypovolaemia or moderate extracellular dehydration.


The sacral parasympathetic reflex pathway regulating colonic motility and defaecation in the cat.

1. The sacral parasympathetic outflow to the large intestine of the cat was studied by monitoring simultaneously intestinal motility and the efferent firing in postganglionic fibres on the serosal surface of the mid-distal colon. 2. Increases in efferent firing were noted during the occurrence of spontaneous propulsive activity (tonic pressure waves) or segmental contractions (slow rhythmic pressure waves). The neural discharge was not altered by transection of the lumbar sympathetic innervation to the colon but was blocked by interruption of the sacral parasympathetic outflow. 3. Electrical stimulation of pelvic nerve afferents arising in the colon or distension of the colon or rectum evoked reflex increases in efferent firing and sustained propulsive contractions that were associated with defaecation. Both responses were abolished by transection of the pelvic nerves or sacral dorsal roots. 4. Electrical stimulation of colonic afferent fibres also evoked synchronous reflex discharges in colonic efferents at latencies ranging from 180 to 300 msec. The discharges were enhanced during propulsive contractions, abolished by transection of the pelvic nerves but not altered by transection of the lumbar sympathetic nerves. 5. Sacral reflexes were present in cats with intact spinal cord and in chronic spinal animals (transection at T10-T12). The reflexes recovered within minutes to several hours after acute transection of the spinal cord. 6. Electrophysiological measurements indicated that the sacral reflexes to the large intestine were mediated by non-myelinated afferent and preganglionic efferent fibres. The central delay for the reflex was estimated to be 45-60 msec. 7. It is concluded that the sacral parasympathetic reflexes to the large intestine are mediated via a spinal pathway and have an essential role in the initiation of propulsive activity during defaecation.