Diminution Of Amplitude Research Articles

Differential involvement of tibialis anterior, gastrocnemius and soleus in muscular dystrophy

In 22 patients suffering from progressive muscular dystrophy (PMD), EMG recordings (measurement of amplitude of volitional action potentials, of the M-wave evoked by supramaximal stimulation of appropriate peripheral nerves and of the H-wave) were obtained from the tibialis anterior, gastrocnemius and soleus muscles in addition to manual examinations of muscular strength. Twelve patients had been diagnosed as suffering from the Duchenne type dystrophy and 10 were classified in the limb-girdle category on the basis of clinical and genetic criteria. Clinical and electromyographic analysis showed that the dystrophic process affected differentially the tibialis anterior, gastrocnemius and soleus. It was possible to demonstrate early electromyographic changes in the tibialis anterior both in the benign limb-girdle type and in the severe Duchenne type of PMD. The electromyographic changes consisted of the characteristic “dystrophic” type of the M-wave and of a diminution in amplitude of the interference pattern and of the M-wave. On the other hand the soleus was well preserved even at a late stage of the disease both in the limb-girdle and Duchenne types. The soleus is eventually involved too in certain very advanced cases of the Duchenne type. When affected, the soleus also shows the characteristic “dystrophic” type of the M-wave, diminution in amplitude of the interference pattern, of the M-wave and of the action potential of tendon jerk, but it continues to produce an H-wave. These findings confirm that the dystrophic process does not affect equally all types of extrafusal muscle fibres. The predominantly tonic soleus is less vulnerable to the dystrophic process than is the mixed tonic and phasic gastrocnemius, while both are less vulnerable than the predominantly phasic tibialis anterior. PMD cannot therefore be defined simply as a degenerative disease of the muscles, but appears to be a selective degenerative disorder affecting only extrafusal muscle fibres; and among these those primarily involved appear to belong to phasic motor units.

Hippocampal responses evoked by stimulation of the prepyriform cortex in the rat

1. 1. Electrophysiological characteristics of the hippocampal response to stimulation of the prepyriform cortex and, in a few cases, to stimulation of the olfactory bulb were investigated in rats with chronically implanted electrodes. Two main types of prepyriform-evoked responses were observed: a diphasic response initially positive in the fascia dentata, and a double monophasic response also positive in the fascia dentata. Transition from one type of response to the other occurred with changes in polarity, intensity and rate of stimulation. 2. 2. Latency of the prepyriform-evoked hippocampal response was 10 msec and maximal amplitude was 1–2 mV in the awake animal. Hippocampal responses were elicited more easily during pentobarbital anesthesia than in the awake rat. Latency and amplitude were increased up to 250% and 800%, respectively, during pentobarbital anesthesia, during post-seizure depression and after tentanization (200/sec for 15 sec) of the prepyriform cortex. A close correlation between behavioral depression; i.e., either behavioral sleep or motor quiescence, and increased latency and amplitude of the hippocampal response was observed during pentobarbital anesthesia and post-seizure depression. 3. 3. After tetanization of the prepyriform cortex 3 phases of amplitude changes in response to 2/sec prepyriform stimulation frequently occurred in the awake and in the anesthetized animal: an initial potentiation reaching a maximum in about 1 min, a period of diminution in amplitude after 2–3 min, during which responses often could not be elicited, and a second potentiation lasting for about 5 min and usually greater than the first potentiation. Latency was increased, never decreased, during the post-tetanic phases in the awake animal. After tetanization during pentobarbital sleep latency was decreased toward values seen in the awake animal.

Effect of varying the gain of a visual display of positional error on some aspects of human tracking performance

The effects of varying the gain of a visual display of positional error by a factor of 4 on performance during a compensatory tracking task with zero input were studied. Measurements were confined to the movements occurring at 4–12 c/s. When the display gain was increased from an initial reference setting to 4 times this level, 9 subjects showed a reduction in error amplitude. Statistical analysis showed that this change was significant beyond the 5% or 1% level in 4 of these 9 subjects. One subject showed a small non-significant increase in error amplitude when the display gain was increased. Frequency analysis showed that the change in amplitude (usually a reduction) occurred throughout the 4–12 c/s range. Of the 9 subjects who showed a reduction in error with a high gain display of position, 5 showed a uniform diminution in amplitude throughout the 4–12 c/s frequency range, and 4 showed a relatively marked degree of attenuation of the peak in the spectrum at 7–10 c/s. The possible nature of the mechanism underlying these effects is discussed.

Alterations of averaged photic evoked potentials in cat visual cortex during repetitive stimulation

1. (1) Photic evoked potentials were studied in 7 cats with implanted electrodes. Variations in intensity of light stimulus due to variations in pupillary diameter were prevented by the use of a contact-occluder technique. The Computer of Average Transients was employed for response definition. 2. (2) Averaged evoked potentials to a brief light flash were analysed into multiple distinct components. A series of 5–8 rapid deflections occurred in the initial 125 msec after the stimulus. These were followed by a series of slower deflections. Components of the response could be identified at latencies as long as 750 msec. 3. (3) Under the conditions of these experiments in which pupillary diameter was controlled, progressive diminution in amplitude or disappearance of the evoked potential, at different frequencies and intensities of repetitive stimulation, was not observed. Consistent changes occurred, however, in the form or organization of various response components during prolonged repetitive stimulation. 4. (4) During prolonged repetitive photic stimulation the following relations to spontaneous changes in level of arousal (as judged by the ECoG) were observed: (a) the mean amplitude of all deflections, exclusive of the initial short latency response, increased during sleep and decreased during arousal; (b) the mean latency of the initial deflection was decreased during arousal. 5. (5) When more distinct periods of arousal (low voltage fast activity) were induced by external stimuli, a decrease in latency and shortened duration of the early multiple deflections was observed. 6. (6) These effects on latency and duration of the various components of the evoked response during arousal, are offered as further evidence for a facilitatory effect of the nonspecific system on transmission in the primary visual pathway.

Transient electromagnetic field propagation through infinite sheets, into spherical shells, and into hollow cylinders

Gaussian electromagnetic field pulses of several durations are propagated through infinite sheets into the interior of hollow cylinders and into the interior of spherical shells. The plates, spheres and cylinders are made of aluminum and contain no slots. The time history of the propagated pulses is computed. Finally, the time sequence of the electric field is calculated in the interior of a cylinder of finite length when connected at its ends by wires to a generator delivering a current pulse of Gaussian shape. The dimensions of the cavities are assumed to be sufficiently small so that resonances are not excited by the highest significant frequency contained in the shortest pulse considered. The numerical study is restricted to thin-walled aluminum shields 1/32 inch, 1/16 inch, 1/8 inch and 1/4 inch thick. The half-amplitude widths of the pulses employed lie in the range 14 \mu sec to 2400 \mu sec. It is shown that the resultant Gaussian pulse electric fields defined on the surface of the plates and cylinders are propagated with little diminution in amplitude. This is understandable due to the requirement that the tangential fields are continuous across the interfaces, and to the fact that skin effect is almost nonexistent at low frequencies. The incident (as contrasted to resultant) field pulse undergoes reflection at the boundary surface. Hence, the attenuation sustained by the incident field is great, since reflection is the chief mechanism of attenuation of fields at low frequencies. Thin spherical shells form effective magnetic shields. The electric field is small in the interior of thin-walled cylinders carrying extremely large transient currents.

ELECTROGRAPHIC AND EVOKED POTENTIAL STUDIES DURING SLEEP IN THE CAT (THE STUDY ON SLEEP, I).

SummaryIn order to study the neural mechanism underlying the physiological sleep of the cat, especially of the stage of sleep characterized by an electrographic pattern similar to those of the arousal stage and also by disappearance of the postural muscle tone, the spontaneous electrograms of the brain as well as the evoked potentials induced by stimulation of peripheral and central nervous structures were studied in different stages of sleep by using chronically implanted cats.(1) Physiological sleep of the cat was divided into 4 stages: A (arousal), S1 (sleep with 6 to 14 c/sec. spindle burst in the neocortical electrogram), S2 (sleep with spindle burst and high voltage slow activity in the neocortical electrogram) and Sa (sleep with electrographic features similar to those of the arousal stage) stages.(2) It was difficult to differentiate between the low voltage fast activity in the neocortical electrograms during the Sa stage and those during the arousal stage.(3) The hippocampal rhythmic activity was of higher frequency during the Sa stage than in the arousal stage. The frequency became particularly high during the period of the rapid eye movements in the Sa stage.(4) During the Sa stage, spindle burst of 10 to 14 c/sec. activity was frequently observed in the caudal pontine and bulbar reticular formation with or without concomitant spindle burst in the neocortical electrogram. Spindles of 6 to 10 c/sec. were seen less frequently.(5) Evoked potentials in the specific systems induced by direct electric stimulation of the brain decreased amplitude during the S1 and S2 stages with slow background activity and showed the amplitude equal to or higher than the arousal level during the Sa stage. The enhancement of the evoked potential appeared more remarkably when low frequency repetitive stimulation was used. The amplitude of the evoked potential was particularly large during the period of the rapid eye movements in the Sa stage.(6) Evoked potentials in the non‐specific thalamocortical system such as the recruiting response were enhanced in the S1 and S2 stages and suppressed during the Sa stage of sleep.(7) Some components of the evoked potential in the mesencephalic reticular formation showed diminution of amplitude in the S1 and S2 stages and enhancement in the Sa stage, while those in the caudal pontine and bulbar level showed marked suppression during the Sa stage.(8) It was suggested that the Sa stage of sleep might be due to the inhibitory process in the lower brain stem. The hypothesis was presented that during the Sa stage, the structures lying above the mesencephalon was in the state of overactivation due to release from the ascending inhibitory (EEG synchronizing) mechanism of the lower brain stem.

The unsteady motion of an infinite oscillating cylinder in an incompressible Newtonian fluid at rest

The motion of an incompressible, Newtonian fluid inside a hollow cylinder and also outside the cylinder is examined when the cylinder is impulsively started from rest and oscillated sinusoidally. The solutions are given in terms of an amplitude diminution and change of phase angle with distance from the cylinder wall.

Electrophysiological studies on the intestinal intrinsic reflex.

1. Two kinds of the intestinal intrinsic reflexes were investigated by recording the electrical activities of the denervated small intestine in the dog anesthetized with morphine and urethan. The electrical activities were recorded in most cases by means of the microelectrode inserted into the muscular coats and occasionally by an agar-agar-AgCl electrode.2. When the mucosa is stimulated mechanically or chemically, the rate of the positive slow potentials and the number of the spike potentials superimposed on them increase above the stimulated spot, while below the stimulated spot the former increases slightly in rate, being accompanied by a diminution in amplitude, and the latter diminishes in number or disappears completely.3. When the intestinal muscle is stimulated mechanically or chemically, both above and below the stimulated spot all the spike potentials disappear and the slow potentials decrease in amplitude, being accompanied by increase in rate.

Dependence of the inotropic action of strophanthin on frequency and the post-extrasystolic potentiation.

1. Inotropic action of g-strophanthin (1∶4,000.000), its dependence on stimulation frequency, and changes of two main factors determining the contractile force in relation to activity rate, „restitution” and „potentiation” effects, have been examined in isolated left auricles of guinea pig and rat. 2. Evolution and extent of the positively inotropic effect of strophanthin in guinea pig auricles vary with the frequency of stimulation (fig. 1). The inotropic effect is inversely proportional to the initial basal amplitude, greatest at the rate of 30 p. min., and smallest at 120 p. min., its evolution being slowest at the low rate, and fastest at the high rate of activity. 3. The diminution of contraction amplitude (both actual and proportional) after a shortening of the interval is smaller after strophanthin than before (fig. 2 and 3). The restitution effect thus is conspicuously augmented by the glycoside. 4. The actual change in potentiation is small (fig. 2), its relative value decreases with strophanthin, owing to the increase in basal amplitude (fig. 3). 5. In the guinea pig right atria the rate of spontaneous activity as well as the amplitude of contractions increase after strophanthin. Both changes, however, are not parallel (fig. 4). All effects of strophanthin in guinea pig auricles are reversible. 6. In the rat atria all effects of strophanthin (1∶4,000.000) in identical experimental conditions are very small in opposite sense than in the guinea pig and mostly irreversible. The rat heart muscle with a very low faculty of potentiation has a singular position, and with regard to its contractility, cannot be considered as representative of the mammalian myocardium. 7. Experimental analysis of the remarkably regular variations of the myocardial mechanical response in their relationships to stimulation frequency, provides a common basis for interpreting a number of known facts, and seems promising as a new approach in the investigations of pharmacological inotropic effects.

Influence of asphyxia on membrane potential level and action potentials of spinal motoand interneurons.

AbstractKolmodin, G. M. and C. R. Skoglund. Influence of asphyxia on membrane potential level and action potentials of spinal moto‐ and interneurons. Acta physiol. scand. 1959. 45. 1–18. — Asphyxial changes in spinal moto‐ and interneurons of decapitate cats were studied by means of intracellular microelectrodes. In both types of neurons the first change in membrane potential was usually observed after about 30 sec in the form of a depolarization of 5–10 mV which after some 30 sec was followed by a phase of more rapidly developing depolarization of larger amplitude; during recovery a phase of increased polarization may be observed. Interneurons showed signs of being more resistant to asphyxia than moto‐neurons. The spib potential underwent a. successive diminution in amplitude, at first owing to the decrease in membrane potential value, later also due to a change in spike peak level. During the later stage of asphyxia a decrease of both the rate of rise of the ascending and the rate of decay of the descending spike phases could be demonstrated. Rhythmical interneuron discharges showed periods of increased and decreased frequency before final blocking.

The electroencephalogram in pernicious anaemia and subacute combined degeneration of the cord

Eighty cases of pernicious anaemia in relapse, of which 24 had subacute combined degeneration of the cord (one with optic atrophy), 41 mild neurological involvement and 15 none, have been studied by means of the EEG. Seven cases showed mild organic reactions and in all of these the pre-treatment record was abnormal. The pre-treatment record was also abnormal in 60 per cent of the remaining patients who showed no significant mental abnormality. In some cases abnormality was severe (delta activity, generalised, paroxysmal or focal), in some slight (slight or moderate excess of theta activity), but the degree of abnormality bore no relationship to the severity of the anaemia, the age of the patient or the degree of neurological involvement. Ten cases of anaemia of miscellaneous type were also studied before treatment; although in 3 of these the haemoglobin level was less than 40 per cent, only in one case did the EEG show a significant abnormality and this patient had severe hypertension and atherosclerosis. Seventy-six of the cases of pernicious anaemia were re-examined after treatment with vitamin B 12. In 14 of the 29 cases which gave normal records before treatment there was a significant increase in mean frequency of the alpha rhythm and diminution in overall amplitude. Forty-two of the remaining 47 cases in which the initial record was abnormal s showed a satisfactory clinical response to treatment and in 31 (74 per cent) the EEG returned to normal, so that 60 of the 76 cases (79 per cent) eventually gave normal records. Improvement in the record began as a rule 7–10 days after the beginning of treatment and was often complete within a month, although some cases showed further improvement after intervals varying from 3–16 months. In the other 11 cases (26 per cent) who responded, persisting abnormalities consisted of a slight excess of generalised theta activity, a finding which in some could possibly be accounted for by age or constitution. Another 50 cases of pernicious anaemia (including 37 with subacute combined degeneration of the cord, 8 with mild neurological involvement and one with optic atrophy) were first studied after treatment had been in progress for between 3 months and 8 years (average 18 months). Excluding 5 cases showing epileptic discharges, 38 (84 per cent) of the other 45 patients had normal records; the remaining 7 cases (16 per cent) were restudied and in all EEG showed further improvement 5 months to 3 years after the beginning of treatment. The final total of normal records was 42 (93 per cent). Eight (6 per cent) of the 130 cases of pernicious anaemia studied gave records showing epileptic discharges (usually temporal spikes or sharp waves) and of these 4 (3 per cent) gave a personal or family history of fits or faints. It is suggested that the EEG changes in pernicious anaemia are due not to the anaemia but to a specific defect in cerebral metabolism, presumably related to the deficiency state responsible for the anaemia. Though not as sensitive as studies of cerebral metabolism by the blood flow method, the EEG is a useful tool in the investigation of these cases and reveals that maximum improvement may be delayed for up to 3 years after treatment has begun. The possible relationship of the EEG changes to alterations in glucose and pyruvate metabolism is discussed.

Studies on the functions and fiber connections of the amygdaloid nuclei and periamygdaloid cortex experiment on the respiratory movements. II.

SummaryThrough stimulation of the lateral amygdaloid nucleus (M of Völsch) we could produce remarkable changes upon respiratory movements, namely, diminution of amplitude and increase in the rate of respiration. The stimulation of the intermediate or medial nucleus of amygdala proper (T or T of Völsch, basal amygdaloid nucleus of Fox) may not bring about changes upon the respiratory movements; if effective, it is typified in the increase in the rate and amplitude of respiration, as it was previously recognized through stimulation of the periamygdaloid cortex. The motion of the diaphragm stands still at the moment of stimulation, regardless as to whether it stands in expiratory or in inspiratory position. The histological observation of the lungs revealed that changes such as hemorrhage, congestion, emphysematous and edematous change, were ext: aordinarily severe in the stimulated side, except in a few instances where much severe damage was shown in the contralateral side.

STUDIES OX THE FUNCTIONS AND FIRER CON‐NECTIONS OF THE AMYGDALOID NUCLEI AND PERIAMYGDALOID CORTEX. EXPERIMENT ON THE RESPIRATORY MOVEMEIVTTS (I).

SummaryThrough electrical stimulation of a delimited part of the amygdaloid nuclei remarkable change in respiratory movements was recognized in the cat and rabbit. The change is typified in diminution of amplitude and increase in the rate of respiration. Sometimes apnoea was seen at the beginning of stimulation. Experiments ascertained that these phenomena resulted by merit of the neuronal transmission through stria terminalis upon the respiratory cent‐r in hypothalamus. By dissections of the stimulated animals it was found that the lung exhibited in all cases many flecks of hemorrhage. In general, change was more pronounced in the stimulated side of the lung than in the opposite side. Through injection of aqueous solution of sodium glutaminate we could obtain also a peculiar change in respiratory movements, dissection showing unusually severe damage in the lung.

Forced crying and laughing; treatment with atropine and atropine-like agents.

IN THE course of pharmacologic therapy of a patient who exhibited Parkinsonian phenomena associated with forced crying and laughing, it was observed, as a result of medication, that, together with the diminution in tremor amplitude, there was a definite decrease in the frequency and intensity of the paroxysmal episodes of crying and laughing. On the basis of this observation, a series of nine patients showing the phenomenon of forced crying and laughing were given atropine or atropine-like drugs to determine whether these medicaments might be an effective means for the control or modification of this patterned motor discharge. The nine patients who exhibited episodic uncontrolled laughing and/or crying were systematically studied before and after the administration of scopolamine hydrobromide U. S. P. (orally) or atropine sulfate (subcutaneously) in doses of 1/150 to 1/100 grain (0.4 to 0.6 mg.) three times a day. In certain cases the patients were placed under

Electroencephalographic changes associated with experimental temporary focal cerebral anemia

1. 1. The right middle cerebral artery was occluded in 19 monkeys, in 9 animals permanently and in 10 animals for periods varying from 10 to 50 min. During each procedure a continuous cortical electrogram was made, and scalp records were obtained at intervals post-operatively. 2. 2. A decrease in electrical potential occurred within 1 min. following occlusion, in all but four animals. This decrease was not proportional to the size of the infarct which subsequently developed. 3. 3. In 9 of the 10 animals with temporary occlusion, some restoration of potential occurred within 30 min. following the termination of occlusion. In 5 of these the potential returned to the pre-operative level in this period. 4. 4. In about two-thirds of the post-operative scalp records there was a persistent diminution of amplitude over the region of the infarct or over the entire right hemisphere. 5. 5. Slow waves, appearing in only two animals during operation, were consistently present post-operatively in about one-half of the animals. 6. 6. Abnormal rhythmic patterns appeared in two-thirds of the animals, but clinical seizures were observed in only three, whose middle cerebral arteries were occluded for 40 min., 40 min. and 30 min. respectively. In each instance these seizures involved the contralateral arm and face. 7. 7. Epileptiform activity appeared in the EEG from the contralateral as well as the ipsilateral side in 3 animals.

Aeolotrophy and Seismology

THE mathematical problem of the seismological implications of aeolotrophy in continental structure has been discussed by Robert Stoneley (Mon. Not. Roy. Astro Soc., Geophysical Supplement, 5, No. 8, 343 ; 1949). He finds that for near earthquakes, erronemous values of the focal depth and thickness of layer might be found from the observations if the continental material had been thought to be isotropic. Further, for a transversely isotropic continent, SH waves would travel with a different velocity from that of S V, and the law of variation of velocity with direction would be different. With body waves, the sharp distinction into compressional and distortional waves would not hold, and an explosion would generate an S wave as well as a P wave ; an apparent difference in the instant of generation of P and S might arise. Stoneley has also proved that waves of the Rayleigh type can be propagated over the surface of a transversely isotropic body in which the axis of circular symmetry is normal to the free surface, supposed plane ; in such waves the diminution of amplitude with depth is shown to be different from that in an isotropic body, so that the amplitudes of the surface waves generated by a source at a given depth will be different from that which they would be in an isotropic medium. Love waves can be propagated as in isotropic media. Byerly noted a possible double refraction effect on the crust of the earth for waves from the earthquake of July 6, 1934 (Butt. Seism. Soc. Amer., 28, 12 ; 1938). Miss I. Lehmann may also have noted a similar effect (Pub. Bur. Cent. Seism. Int., A, No. 12, 109 ; 1935).

THE SEISMOLOGICAL IMPLICATIONS OF AEOLOTROPY IN CONTINENTAL STRUCTURE

The seismological consequences of a departure from isotropy in the surface layers of the Earth are discussed. It is noted that erroneous values of the focal depth and the thickness of the layers might be found in near earthquakes. For a transversely isotropic continent it is shown that SH waves would travel with a different velocity from that of SV, and that the law of variation of velocity with direction is different. With body waves the sharp distinction into compressional and distortional waves does not hold, and an explosion would generate an S wave as well as a P wave; an apparent difference in the instant of generation of P and S might arise. It is proved that waves of the Rayleigh type can be propagated over the surface of a transversely isotropic body in which the axis of circular symmetry is normal to the free surface, supposed plane; in such waves the diminution of amplitude with depth is different from that in an isotropic body, so that the amplitudes of the surface waves generated by a source at a given depth will be different from what they would be in an isotropic medium. Love waves can be propagated as in isotropic media.

Electroencephalographical Changes during Mental Efforts

Summary Now, to summarize the above statements, in case of mental work such as mental arithmetics the α-wave of -the brain tends to diminish its amplitude in one: hand arid to increase it:; frequency in the other hand. The mode and grade of reaction do not differ thereby from those of sensory stimulation. I However, there is a slight difference in the blockin:; time and the suppression course in both, which indicates a n aspect o f the mode of the human rnental work. Also it has been proved that the: change in the α-wave at mental arithmetics is not altogether based on the accompanying optical factor. No particular variation of the α-wave suppression was percc3ived at mental work in the different portion of tic. skull. By analysing the amplitude distribution curve a simple increase in excitability in the brain cortex was perceived during mental activity. As is stated in the introduction and as the. experment of Lontlmr*d, EidtoiA and Lenizox tells, the increase in the cerebral blood flow is perceived during mental work. Accordingly, the phenomenon of diminution of the amplitude and increase of the frequency in the brain wave tied up with increase of the brain blood flow may be looked upon as indicating one aspect of the brain activity during mental work. In this case whether the increase of tile brain blood flow causes the change in the α-wave or, in reverse, the changed tone of the nerve cell effecting changes in the α-wave. causes secondarily the acceleration of the brain blood flow remains still undecided. However, the fact that even though the brain blood flow is passively increased by aderenalin injection no remarkable change was perceived in the lT-wave, offers basis to the supposition that the change of the α-wave is primary. Only, existence of the distinct α-wave difference between sensory activity and purely mental activity is not yet ascertained. Concerning the brain blood flow there is Gerard s30 report where a simple optic stimulus is sufficient to cause a n increase in the blood flow in a part of the opticalarea, which speaks for the. supposition that increase of the blood flow can occur accompanying both sensory as well as mental activities. Also in case of the α-wave the diminution of amplitude and the increase of frequency occur both at sensory and mental activities, whereby there is noticable among them certain difference in the time course and a few other moments. Lastly the thesis that the diminution of the α-wave amplitude is primarily caused through excitement of nerve cell may appear to be less founded or rather contradicting, t d clarify which point Jasper's30) energy theory may serve helping understanding to some extent.

The influence of hook-worm infection on the heart muscle—an experimental investigation

1. The influence of hook-worm infection on the heart muscle is investigated by perfusing isolated frog hearts with different concentrations of blood sera of patients suffering from Ankylostomiasis. 2. It is observed that in concentrations of 1 in 106 and 1 in 105 the sera produce a diminution of the Amplitude of the beats indicating the presence of a toxic factor in the sera. 3. The toxic effect disappears in a few cases after iron therapy and disappears completely or is considerably diminished after anthelmintic treatment. 4. It is concluded subject to further experimentation that some factor yet to be isolated is present in the blood serum in Ankylostomiasis which exercises a toxic effect on the cardiac muscle and on the blood-forming organs.

A phonocardiographic study of the heart sounds in acute coronary occlusion

A phonocardiographic analysis employing microphones of different frequency filtering and transmission range was made of the heart sounds in seventy-eight cases of acute coronary occlusion and in 100 normal control subjects. The results were correlated with the clinical findings. The first heart sound was absolutely diminished in amplitude in 24 per cent and relatively to the second sound in 54 per cent of the patients with acute coronary occlusion. This diminution in amplitude affected the central group of high-frequency vibrations and was attributed to the change in the physical character of the infarcted left ventricle and possibly, in the first few days of illness, to the lowered intraventricular pressure following acute myocardial infarction. Occasionally the second sound at the apex is increased to an absolute as well as a relative value. An auricular sound was present in 83 per cent of cases of coronary occlusion compared to 38 per cent in normal subjects. In one-third of the cases of coronary occlusion the auricular sound was accentuated and formed presystolic gallop rhythm. This never occurred in normal subjects. Accentuation of the auricular sound was probably the result of the increased intra-auricular pressure following ventricular infarction. It was practically always associated with heart failure. A third sound occurred in 47 per cent of the cases of coronary occlusion as compared to 12 per cent in normal subjects. The high incidence in the former was attributed to the decreased tonus of the infarcted ventricular muscle. In 9 per cent of the cases the third sound appeared accentuated and produced protodiastolic gallop rhythm. Heart failure was invariably associated with it. Superimposition of the auricular and third sounds of normal or accentuated amplitude occurred in 6 per cent of cases, forming summation gallop. This type of gallop rhythm was also associated with heart failure. Clinical heart failure was present in 63 per cent of the cases of coronary occlusion. It occurred predominantly in those who presented a first sound of diminished amplitude (88 per cent) and gallop rhythm (95 per cent). It was much less common in those with an unimpaired first sound (33 per cent). This emphasizes not only the close relationship between impaired heart sounds and heart failure but also the serious import of a diminished first heart sound and gallop rhythm. Gallop rhythm may be present before signs of heart failure are apparent. The impairment of the first heart sound following coronary occlusion is often permanent and may be the only persistent sign following recovery. It thus may be of diagnostic significance.