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Sr ftaxizenall j D, quc^t $\ (y)a^tcX..u / L Ccctmi^cjL. ^ <5^ dE>70^4/X^ t.P &CCA dA^J. pAdphd hi11 tAs. L(Aaa*j l ,. ............TT. Quf , CJUw~t 3^0)^ ^3r.Ch&\tLj . (S S"................................ , DUP050043864 ^Auw"\ Qx^jae*. J V6j3m Cct 8 i>l<nrd \ta$ CecweJpM R'lfVD. JtekwvVv- ^ wft-. hsJ6t..Dap inC|u5^ ouxj. $ A . V> ^vj o xj ** t%%& \ VlcJlt^ in G> dtfvp r., G fcffv^p x s.e, 6Rt. av ?^v DUP050043865 uftVtL. 'i p v <j>v Cy\-<nM> . .7?. ujifu. ?C /v*/Vu aa ^felL^sgy- b If^A, 6u a X OLAtJU^i.- -|L -O, J . (pzoixf P( 4 ".' Ii:rrn 1 QvO^> ^ flo . `Ct^XKvt `*p"*r * " " j IfffsZSlcl 0w &srtNt^y n j u JKm- (^ QtfU&PU X. O-Arput^c , l^wl Vf>V> C^v ^ M.C^^ n^u?^ I^>5 \ ^ grj- CacJJTi Uf^v4 ^l **4 Ach^- . C^/v<y Tj, VtH.pu.*} -VL t o*. U~> \v- \^.k^, /j ,. nait* 1pQirYdb> fft r -5, .0,31| ^>c 0,760^ (sV-- **r < ^ wUH DUP050043866 7l ^ . \ JL /W<K e;* /I MgloijfW/ (\ . ..VU slf^ ^ TV ITIRO C, ^ ft , ,,.t??r.. /^.W0t'Y. ... ,>V-r. .....u* ^vl^wyT/aT^es^ '2E. .. |p<Wfr .**".0.. 44?: ](vV*CiAwJC . A tM. ,,., ,V&. Alt*;VW! . i- l...<U^A ...... . .t ~ o. ftp 4...r ..x 0-H7A...... ...... r. fe. <A (V. <J^r ^ .......... ...jy fu ''evf^u- >. /^> a; cf^Ctiu /-- ^ , DUP050043867 THE EJfEECI OF INORGANIC LEAD UPON THE CONDUCTION / VELOCITY OF THE PERIPHERAL NERVES OF EATS AND DOGS Medical Research Project No. HR-787 Among the insidious effects of inorganic lead upon animal tissue is its action upon peripheral neuromuscular structures. In lead poisoning clinical evidence of neuromuscular involvement may be absent; when present, it may vary from a mild weakness to paralysis of the musculature affected. "Wrist-drop or paralysis of other muscles may be fore-shadowed by gradual weakening or may occur without any premonitory symptoms and generally unpreceded by pain. The parts frequently affected are the extensors of the fingers, thumbs and wrists, but the muscles of the leg or feet are often attacked, sometimes the back, and l in rare forms of poisoning the muscles of the eyes" (10). ' Today lead-exposed workers seldom develop muscular paralysis (1) due to preventive measures against lead absorption; however, any individual with clinical lead poisoning is a potential victim of this paralysis. The site of this deleterious action of lead on the neuromuscular system has not been definitely established (5, 8, 9). There is some evidence that lead may affect the muscle directly by interfering with its metabolism (8). On the other hand, the demonstration of segmental demyelination of nerves obtained from lead-poisoned guinea pigs (5\ is strong evidence that peripheral nerves are primary sites of the action of lead; the subsequent disturbance in the conduc tion of impulses along an injured nerve would account for the paralysis of the affected muscles. Finally, although evidence for this is lacking, lead might act at the motor end-plate, that microscopic area where the nerve fiber terminates in close proximity to the muscle fiber and where, probably by chemical means, the nerve- irpul.se acts to initiate the muscular contraction. At this point, N37513.01 \ DUP050043868 interference with the excitation of the muscle fiber would also result in paralysis. Since most of the available clinical and pathological evidence favors the motor nerve as the prime target of the action of lead on peripheral neuromuscular structures (8), it was decided to try to detect the presence of peripheral nerve damage in animals fed lead acetate, using a physiological technique which could be utilized in the study .of any potentially neurotoxic compound, A physiological method for detecting peripheral nerve damage is the measurement of impulse conduction velocity between two points along a nerve trunk, a' technique undergoing extensive clinical trial. Impulse conduction velocity is decreased in the area of a local compression lesion (12), in many cases of acute polyneuritis (2, 12), which finding may differentiate this condition from acute poliomyelitis (12), and in diabetes mellitus (3, 6, 13, 14, 16, 20). There have been several reports of slowed conduction along the ulnar nerve attributed to industrial poisons. These include 15 patients with occupational lead poisoning without neurological symptoms (l8) and ten women with severe polyneuropathy assoc iated with chronic triorthocresyl phosphate poisoning (17). 3h addition, "borderline" slowing was observed in two patients with lead neuropathy and in five with s neuropathy due to the cutaneous absorption of an industrial solvent* (19). Animal esperiments correlate slowed conduction velocity with clinical, and some times histological, evidence of nerve damage: in allergic polyneuritis in guinea pigs (11), in diphtheric polyneuritis in cats (15) and guinea pigs (ll), in s.1 Ifysran diabetes in rats (h) and, with histological confirmation, lead poisoning in guinea pigs (5). In view of the clinical and ejperimental evidence correlating nerve damage with slowed conduction velocity, the use of velocity measurements for detecting peripheral nerve injury is promising. It Was decided, therefore, to measure the * 85$ trichloroethylene, 10$ ethylene dichloride, 5$ tritoluol phosphate. DUP050043869 -3 conduction velocities of excised nerves, available at autopsy, from the rats and dogs in the two-year lead feeding study, MR-787, and in a small group of rats fed a higher level of lead. METHODS In principle, measurement of the Impulse conduction velocity of an excised nerve fiber is straightforward, requiring only the measurement of the time it takes for the impulse to travel from one point of the fiber to another. If the distance between the two points is known, the velocity can be calculated. In practice, one end of the fiber is stimulated by passing an electric current through a short section, 3 to 5 mm, between two electrical contacts, the stimulating electrodes. The minute change in the membrane potential, known as the t action potential, which is associated with the impulse as it travels along the fiber, is detected further along the nerve by another electrical contact, the recording electrode. This action potential is amplified and fed into a suitable recording-device, usually a cathode ray oscilloscope. In the present experiments, a nerve trunk containing many fibers was studied. Adequate "maximal" stimulation of a nerve trunk initiates impulses in all of the fibers; each impulse is conducted along its fiber at a rate characteristic of that fiber, rapidly in some, more slowly in others. The action potentials associated with the successive arrivals of the impulses at the recording electrode cause a sustained, sometimes complex, deflection of the oscilloscope beam called the "compound" action potential. At any selected point of the oscilloscope tracing, the magnitude of the deflection is a function of the number of impulses at the recording electrode at that particular instant. DUP050043870 / * lj< M I. Equipment Figure 1 is a photograph of the equipment used in the experiments. From left to right in the photograph are X) the constant temperature shelter in the right portion of which an electrode set is visible, 2) the tele thermometer, 3) the stimulus isolation unit, 4) the recording unit consist ing of amplifier and oscilloscope, and 5) the Tektronix stimulation unit. A. Electrodes. Two electrode sets, one for dog nerves and a smaller one for rat, were designed by Paul E. Smith, Jr., and idade by Edward F. Fabryka, of the Physics Section. Each set consists of a holder made from l/4-inch Teflon sheet supporting a horizontal row of equally spaced and parallel platinum wires (Figure 2). The first two wires at one end of the row serve as the stimulating electrodes, S, , S2j any two of the other wires may serve as recording electrodes*,!?. (Two are necessary to complete the circuit through the recording device.) B. Stimulator. In the earlier experiments a Grass square wave stimulator. Model S4G was used. It was replaced by a Tektronix unit assembled by Paul E. Smith, Jr.; it consists of a pair of Type l6l pulse generators each driven by a Type 162 wave-form generator. Both stimulators provide a stimulus which can be controlled as to duration, voltage, and frequency of application. The strength of the stimulus applied to a nerve was 4 to 10 volts and its duration was 0.06 to 0.1 mSec (milliseconds), In order to minimize the effect of the stimulus current * In addition to the stimulating electrodes, the small holder has nine recording electrodes spaced every 5 mm; maximum available conduction distance: 4 cm. The large holder has 20 recording electrodes spaced 10 mm apart, maximum conduction distance: l8.5 cm. In addition, the large set has "dummy" wires between electrodes to give added support to the nerve and minimize sagging. DUP050043871 t -5 - upon the oscilloscope beam, an isolation unit, "3" in Figure 1, was placed in the stimulation circuit between the stimulator and the nerve: a Grass SIU 478 A isolation unit with the Grass stimulator and an Argonaut LIT O69 isolation transformer with the Tektronix, C. Recording Equipment, Tektronix units were used. The nerve action potentials were amplified by a differential amplifier, Type 2A63 or Type 3A5 Dual Trace*, and fed into a Type 5&1A Cathode ray oscilloscope. The ,P sweep of the oscilloscope beam was triggered by a mechanism within the stimulator; the speed of the sweep was controlled by a Type 2B67 time base' Which has a range of 1 microsecond to 5 seconds per screen division. The oscilloscope tracing was photographed with a Tektronix C 12 camera unit using Polaroid Type 4.10 black and White land film. Measurements were made directly from the photographs. D. Constant Temperature Shelter. During experiments nerves must remain moist and, in addition, mammalian nerves must be kept at or near body temperature, 37C (98.6F), if conduction velocities are to be equivalent to those in the intact animal. Mammalian nerves are usually mounted within a small protective chamber which is suspended in or abovq, a water bath. In most of the present experiments, however, 16 to 20 nerves had to be tested daily so that a fresh nerve had to he mounted every 10 to 20 minutes and the temperature of even a small protective chamber could not be maintained by a water bath, Therefore a shelter, * Amplification range: Type 2A63: 20 volts to 1 millivolt per screen division. Type 3A3: 10 volts to 0.1 millivolt per screen division. DUP050043872 f -6provided with a continuous and adjustable supply of warm and moist air, was constructed. The shelter* was 36 inches long by 18 inches wide; a sloping roof, 24 l/2 inches high in front and 12 l/2 inches in back, provided drainage for the water which condensed on its inner side. Within, the shelter Was partitioned into a 19 l/2-inch by l8~inch "outer" chamber and a 16 l/2-inch by l8-inch "inner" chamber. The former had a permanent opening in front and was used for mounting the nerves on the electrodes while the latter sheltered the nerves while the action potentials were photographed. A thermistor probe suspended within 4 to 6 cm of the mounted nerve and Connected to a deflection type meter. Tele-Thermometer Model 45, Type TF, permitted a direct reading of the dry bulb temperatore of the inner chamber whenever desired. An ample supply of warm, moist air for the shelter was provided by a constant-temperature room; With the temperature of this room at 43.06*0 (109.5F) dry bulb and 40.28C (104.5F) wet bulb, 87 percent relative humidity; the dry bulb temperature of the inner chamber was maintained at 37.06C 0.4C( 98.7PF 0.72F). II. Nerve Preparations The left hind leg of the animal was obtained from the Pathology Section and the nerve removed: tibialis from the dog and the sciatic with its * 1.' Framework: Equipto Type 5700 hot dip galvanized slotted steel, 1 l/2" x 3" x 0.104". 2. Bach wall which supported the warm air inlets: l/4" Teflon sheet. 3. Other walls, roof, and inner partition: 0,003" Mylar sheeting. DUP050043873 7 tibialis "branch from the rat. During.dissection the nerve was protected against drying by the application of a lactated Ringer's solution* or by a silicone preparation**. The nerves were mounted so that the central end made contact with the stimulating electrodes, the peripheral end (tibialis branch of rat nerves) with the recording electrodes. The rat nerves required five to ten'minutes, the larger dog nerves ten to 15 minutes, to adjust to the environment of the inner chamber as shown by the constancy of the velocity measurement. t t t . The Oscilloscope Tracing and Its Measurement A typical dual tracing***, copied from one obtained on a dog nerve, is shown in Figure 3 The sweep of the oscilloscope beam is from left to rightj 1 its speed 0.2 mSee per division of the screen. The lower response was recorded by an electrode 2.48 cm distal to the stimulating electrodes, the upper by an electrode 2 cm farther along the nerve. The following discussion applies to either response. The first small upward deflection, A, lasting 0.1 mSec is due to the stimulus current and is called the stimulus or shock artifact. Since this current is conducted by the nerve as by a wire so that its arrival at the recording electrode is essentially instantaneous with its application to the nerve, it indicates the time of stimulation in the tracing. After a short delay, * Cutter's for injection. ** 360 medical fluid, viscosity grade 50 cstks. Supplied through the courtesy of the Medical Products Division, Dow-Corning Corporation. *** (Stained with Type 3A3 amplifier which "splits" the beam so that the response to a single stimulus can be recorded from two points along the nerve during a single sweep of the oscilloscope beam. DUP050043874 0.25 mSec in the lower tracing and 0.44 mSec in the upper, there is a large diphasic deflection which is the compound action potential. The two measurements made by Elias son (4) were adopted; the time from the start of the stimulus artifact l) to the beginning of the upstroke of the action potential, the "inflection" 1, Figure 5* caused by the arrival of the most rapidly conducted impulses at the recording electrode, and 2) to the point of maximum deflection, the '^peak" 2, Figure 5, due to the later arrival of * the impulses over. the largest number of similar fibers. These measurements provide the data for the calculation of "inflection" velocity and "peak" velocity, respectively. IV. Animals Studied -l L- `r ' " " ,r-'''i A total of 262 rat and 55 dog nerves were tested. The dogs were electrocuted; the 224 rats of the 2-year feeding study were killed by being chloroformed. The other 58 rats comprised a special high lead dosage group killed by decapitation in order to determine whether chloroform had a signifi cant effect on conduction velocity. Table I gives the groupings of the gniwfliH according to lead dosage level and duration of treatment. j RESULTS I, Validity of Observed Conduction Velocities I. A. ' Sciatic-Tibialis Nerves from Rats. The average conduction | velocities with their standard deviations from the mean are given for each treatment group in Table I. | 1. Nerves from decapitated rats. The nerves from the various groups of decapitated rats had inflection velocities which I. averaged from 6? to 73 m/sec (meters per second). These values I It j 4; } :t :* V. r I DUP050043875 -9- overlap those of 71 and 74 ra/sec reported by Eliasson for nerves obtained from normal and starved decapitated rats (4). However, the averages for the peak velocity ranged from 4l to 45 m/sec, distinctly below his values of 53 and 55 m/sec. 2, Nerves from rats killed by chloroform. When comparisons are limited to the values for equal conduction distances, the nerves from the chloroformed rats of the 18-month treatment groups had higher, and those from the 24-month groups had lower conduction velocities than the nerves from the decapitated animals. Although the average values do not support the expecta tion that chloroform would depress conduction velocity, the larger standard deviations obtained for the measurements made on the ' \ nerves from the chloroformed rats indicate that these prepara tions are not as satisfactory as those obtained from the decapitated animals. B, Tibialis Nerves from Dogs. Unfortunately, technical difficulties with stimulation prevented/satisfactory recording of the action potentials of the nerves from the four male dogs of Group I, and three other dogs were killed before the scheduled autopsy date. However, the data obtained on all of the other nerves are given in Table II. Nerves from the male dogs had inflection velocities ranging from 85 to 105 m/sec and peak velocities ranging from h-8 to 58 m/sec. The corresponding values for the nerves from the females were, respectively, 84 to 102 m/sec and 47 to 56 m/sec. These velocities are within the range for mammalian fibers as listed by Grundfest (7). Because the number of dogs per group is small and since the F test for difference in velocity due DUP050043876 10 to sex* was insignificant, the .data from both sexes were used for calculation of the standard deviations for each treatment group. These standard deviations, ranging from 1.1 to 6.0 m/sec for inflection velocity and from 1.3 to 2.8 m/sec for peak velocity, are comparable to those obtained for the measurements made on nerves from the decapitated rats. This indicates that the preparations from electrocuted animals may be as satisfactory for conduction'velocity studies as those from decapitated animals. II. The Effect of lead Comparison of the conduction velocities of the nerves from the lead-fed animals with the values obtained for their respective controls does not reveal a decrease in velocity due to lead. This conclusion is substantiated by the results of the F test for effect of treatment** which was applied to all of the data obtained at each sacrifice, Table III. With the exception of a significant effect on the inflection velocity of the nerves from the dogs, 0.01 < P < 0.05, lead had no effect on conduction velocity, . This effect of lead on inflection velocity is limited to the nerves obtained from the male dogs (Table III) and consists of a successive increase in velocity as the dosage increases from 10 to 100 ppm. At the dosage level of 500 ppm (Group V), the inflection velocity is reduced. This velocity increase is significant at the 5 percent level whether or not the data from Group V are included in the calculation of F. Other possible causes of this effect have been excluded: preparation time, order in which nerves were tested, and shelter , _ Variance due to Sex f " Variance within Group p _ Variance due to Treatment ' ~ Variance within Group DUP050043877 - 11 - temperatures. Examination of the velocity averages for the nerves from the rats of the 2-year feeding study which were sacrificed at 18 months shows the presence of a similar trend following an initial slowing; however, the trend in this case is statistically insignificant even when the data from the control groups (Groups I and la) are omitted from the calculation of F (Table III), DISCUSSION The values obtained for impulse conduction velocity in these- experiments indicate that such measurements are both practical and valid when made on the type of preparation available at autopsy with the possible exception of those from the animals killed with chloroform. 1. Rats Killed with Chloroform V\ The nerve preparations from these animals might be considered unsatis factory because of the difference in the average velocity values obtained for the nerves from the 18- and 24-month treatment groups and because of the within group variability. However, factors other than the chloroform may account for these discrepancies, such as the 6-month difference in age between two groups and/or an unexplained technical difficulty Which results in an apparent decrease in conduction time when the shelter humidity is very high. A. A decrease in conduction velocity with increasing age has been reported for the nerves from human subjects (5, 13, l4, 16); such a physiological decrease may account for the slower average velocities of the nerves from the older rats. The within group variability might be the result of differences in the amount of fiber deterioration DUP050043878 - 12 - and/or in the amount of damage inflicted by the separation of the nerves from the dense layers of fat in which they were characteris tically embedded, especially in the 24-month animals. B, The technical difficulty is associated with high shelter humidity; it is prominent when the relative humidity is- 90 per cent and higher. It results in an apparent decrease in conduction time* and calcula tion of an erroneously high conduction velocity. As the nerves from the l8~month rats were kept moist with Ringer 's solution** during the dissection, a higher shelter humidity was required to prevent drying than was needed for the silicone-protected nerves from the 24-month animals. The higher velocities of the nerves from the younger rats may he due in part to this technical error. II. The Effect of Lead * Since all of the nerves obtained during the same sacrifice were treated as nearly alike as possible, comparison of the velocities of the nerves from the treated animals with the values obtained for the controls killed during the same sacrifice is valid. The absence of a significant lead effect on the rat nerves supports the observations of Dr. Fullerton who found that, in comparison with nerves from guinea pigs and rabbits, rat nerves are resistant to the toxic action of lead (5), No report on the action of lead on the peripheral nerves of dogs was located in the literature. At the time of autopsy, the male dogs had * Details under technical difficulties, ** Use of the silicone preparation began after the sacrifice of the l8-month rats. DUP050043879 - 13 - significantly higher blood lead concentrations than the females (p < 0.005); this difference in blood lead concentrations correlates with the demonstra tion of a significant lead effect only for the nerves from the male dogs. At the time of sacrifice, all of the dogs appeared healthy and showed no clinical signs of peripheral neuropathy. Ill, Technical Difficulties For comparative purposes technical difficulties which cause variable results can be mostly eliminated or controlled, A. The high humidity of the inner chamber causes a marked tendency for the action potential to move towards, and eventually fuse with, the stimulus artifact as the stimulator voltage is increased. This apparent shortening of the interval between stimulation and response % results in the calculation of falsely high conduction velocities and the magnitude of the error (velocity increase) increases with the voltage used to stimulate the nerve. This error can be minimized by 1) using the silicone preparation so that a lower humidity suffices, 2) stimulating the nerves with the same stimulator voltage which must be supramaximal for all, 3) wiping the electrode holder before mounting each nerve, and 4) using a long conduction distance. B. The effect of conduction distance per se observable in the data of the six-month group of the special study rats. Table I, can be eliminated if conduction distance is standardized. DUP050043880 .1 - Ik C. Conduction time between two recording electrodes. Theoretically, because excitation time is excluded, measurement of the time it takes for impulses to travel the distance between two recording electrodes, rather than between stimulating and recording electrodes, should provide a more exact determination of conduction velocity. However, measurements of the intervals between the inflections, or between the peaks, of the action potentials obtained from two recording electrodes during a single sweep of the oscilloscope beam (Figure 3) provided velocity values which were so variable that this method of measurement 1ms been abandoned temporarily, D. Other causes of variability. Variables which, in these experiments, i could not be correlated with conduction velocities included l) the dry bulb temperature of the inner chamber which had a maximum variation of 1.1C (l.98F) and 2) surprisingly, the time which elapsed, 19 to b? minutes*, between the death of the animal (chloroformed rats; from start of chloroform administration) and the placing of its nerve in the inner chamber. It is possible that the minimum delay between death and mounting, 19 minutes, is longer than some critical interval after which further delay has little additional effect, , CONCLUSIONS 1. Measurement of the impulse conduction velocities of excised nerves obtained from animals at the time of autopsy may provide physiological evidence of the presence of peripheral nerve damage due to the action of toxic compounds. * Special high lead dosage rats: this interval was shorter, ranging from 11 l/2 to 19 minutes. DUP050043881 -15- 2. Inorganic lead, as lead acetate, administered to rats in concentrations as high as 50 ppm daily for two years and in a concentration of 5000 ppm for 13 months had no significant effect on the impulse conduction velocity of the seiatic- tibialis nerves. In concentrations to 500 ppm for two years, lead had a significant effect (0.01 < p < 0.05) on the inflection velocity of the tibialis nerves of the male dogs. This effect consisted of a progressive increase in inflection velocity as the dosage of lead increased from 10 to 100 ppm, rather than the decrease which would be expected if lead were exhibiting an inhibitory effect. ACKNOWLEDGMENTS Special acknowledgment and appreciation for their co-operation and help are due to: Br. G. J. Stopps, who suggested the problem and gave valuable advice, P, E, Smith, Jr., who designed the electrode sets, assembled the Tektronix stimulating and recording units, and gave considerable time to eliminating technical difficulties, E. F. Fabryka, who made the electrode sets and assisted with the electronic equipment. * C. J. Michaels, Jr,, who acted as photographer in several experiments, Georgina M. Binder, who acted as co-ordinator with events in the autopsy room, noted the crucial times during each sacrifice, and assisted .1 with the. calculations. .. The personnel in the autopsy room, especially Mary Ann Eubin and A, Stenholm, who provided the amputated hind legs from which the nerves were excised. MEM/jtd 9/IO/7I DUP050043882 REFERENCES 1. Browning, Ethel, Toxicity of Industrial Metals, p, 157; London. Butterworths. I9&L " ^' 2. Cerra, D. and Johnson, E. W. Motor Nerve Conduction Velocity in "Idiopathic" Polyneuritis, Archives of Physical Medicine and Rehabilitation 42: 159-163, 1961, "~ 3. Downie, A. W. and Newell, D. J. Sensory Nerve Conduction in Patients with Diabetes Mellitus and Controls. Neurology 3d: 876-882, 1961. 4. Eliasson, S, G. Nerve Conduction Changes in Experimental Diabetes. Journal of Clinical Investigation 2353-2358, 1964. 5. - Fullerton, Pamela M. Chronic Peripheral Neuropathy Produced by Lead Poisoning in Guinea Pigs. Journal of Neuropathology & Experimental Neurology 25: - 214-236, 1966. i . ~* 6. Gi.3J.iatt, R, W. and Willison, R. G. Peripheral Nerve Conduction in Diabetic Neuropathy. Journal of Neurosurgery & Psychiatry 25_: 11-18, 1962. 7. Grundfest, H, Bioelectric Potentials. Annual Reviews of Physiology 2: 213-242, 1940. 8. Harvey, S. C. in Pharmacological Basis of therapeutics, Edition 3; L. S. Goodman and A, Gilman, editors. New York, MacMillan, 1965. 9. Hughes, James P. in Pharmacology in Medicine; Victor A, Drill, editor. New York, McGraw-Hill, 1954. 10. Hutton, R M. Lead Poisoning. Provincial Board of Health of Ontario, Toronto, C. W. James, 1923* H. Kaeser, H. F. and Lambert, E. H. Nerve Function Studies in Experimental C Polyneuritis, pp. 29-35 in Progress In Electromyography ^ edited by P. Pinelli, F. Buchthal and F. Thidbaut, ,<s Electroencephalography and Clinical Neurophysiology, Supplement 22; New York, Elsevier, 1962. ** 12. Lambert, E. H. Diagnostic Value of Electrical Stimulation of Motor Nerves. Ibid, pages 9-16. 13. Lawrence, D. G. and Locke, S. Motor Nerve Conduction Velocity in Diabetes. Archives of Neurology 5.: 483-489, 1961. DUP050043883 ill.. Mayer, R. F. Nerve Conduction Studies in Man, Neurology 13.: 1021-1030, 1963, 15. McDonald, W. I. The Effects of Experimental Demyelination on Conduction in Peripheral Nerve. A Histological and Electro* physiological Study. II. Electrcphys iological Observa tions. Brain 86: 501-524, 1963. 16. Mulder, D. W., Lambert, E. H., Bastron, J. A, and Sprague, R. <3. The Neuropathies Associated with Diabetes Mellitus. A Clinical and Electromyographic Study of 103 Dhselected Diabetic Patients. Neurology 11: 275-284, 196I; 17. Sala, E. The Motor Nerve Conduction Velocity in Polyneuropathy due to Chronic Triorthocresyl phosphate Poisoning, in Progress in Electromyography, pp, 29-35 5 Electroencephalography and Clinical Neurophysiology, Supplement 22; New York, Elsevier, 1962. 18. Sessa, T., Ferrari, E. and P'Amato, C. C. Velocita di Conduzione Nervosa nei Saturnii. ' ___ Folia Medica 48: 658-668, 1965. .4 19. Simpson, J. A. Conduction Velocity of Peripheral Nerves in Human Metabolic Disorders, in Progress in Electromyography, pp. 36-435 Electroencephalography and Clinical Neurophysiology, Supplement 22; New York, Elsevier, 1962. 20. Skillman, T. 0., Johnson, E. W., Hamwi, G. J. and Driskill, H. J. Motor Nerve Conduction Velocity in Diabetes Mellitus. Diabetes 10: 46-51, 1961. DUP050043884 f Group * No. Lead, ppm. Added to Food t abl e I IMPULSE CONDUCTION VELOCITY Conduction Distance CMS N ` Average Conduction Velocity S.D.* Inflection; m/Sec. Peak: m/sec. Males Females Males Females RATS OF SPECIAL STUDY; KILLED BY DECAPITATION 6-Months Treatment. Silicon Oil Used. I II i+ii 0 ' 5000 13-Months Treatment. I II" i+n 0 5000 2.47 K2.97 2.47 K2-97 2.47 2.97 Silicon Oil Used. U 2.96 1/2.96 2.96 9 10 ~19 9 10 19 7 014.9 ' 7015.1 6713.9 7 6913.2 " 6914.4 7014,0 7314,8 7015,0 -- 7115.0 4110.7 441-1.5 4111.6 4411.8 4111.3 4411,7 4512.3 4413.2 44d;28 --( fik. cRa ATS OF 2-YEAR FEEDING STUDY KILLED BY CHLOROFORM 18-Months Treatment. Ringer's Solution Used. ,, 1 IA II III IV V i-V 0 2.5 6c? 6? '7917.3 7816.8 0 2.5 6c? 6? 7617.5 7714.3 10 2.5 6c? 6? 7119.8 71114,0 50 2,5 6c? 6? 8014,7 7 418,4 100 2.5 6c? 6? 8119,7 7617.4 500 2.5 6c? 6? 7717.6 7815.5 2.5 72 7618 .3 r k? & jC - 4613.6 4512,1 4311.1 4412.7 4316.4 4413.9 4H6.0 4413.4 4713.8 4411.8 4211.7 4412.6 4413 .6 24-Months Treatment. Silicon Oil Used. i IA II III IV** v*** i-v 0 2.97 12c? 16$ 65113.7 6515,3 0 2.97 13c? 12? 6715.8 6316.0 10 2.97 13c? 16? 6517.3 6414.3 50 - 2.97 12c? 16? 6514,6 6414.8 100 2,97 12-13c? 17? 6413,9 6419.0 500 2.97 0c? 12? 6314.9 2.97 151-152 646 ,8 { (' < 3714.9 3814.1 3815.6 3615.5 3813.6 3813.1 3614.4 3915.1 3714.8 3714.2 3714.1 3714.4 * S.D. - Standard deviation from the mean. ** In one photograph inflection velocity could not be determined. *** Group V males sacrificed early. DUP050043885 Male Dogs Avg. Female Dogs Avg. Males + Females Avg. S J>. t /Male Dogs Avg. Female Dogs Avg. Males + Females Avg. S.D.t TABLE II IMPULSE CONDUCTION VELOCITIES: DOG NERVES* TREATMENT GROUP AND LEAD ADDED TO DIET IS" ^ I II III . IV ' 0 10 ppm 50 ppm 1QQ ppm V 500 ppm V ;-s 7*o<+ 'T "93 87 92 93 91.2 INFLECTION VELOCITY: METERS PER SECOND 83 .87 UV .92} * 86.5^ ,v 84) / > 88/7 89.5 102 98 92 89 r 95.2 99 99 105 93 99.0 92 ...... 91 89 102 93.5 ... 85 .....^ 93 93 92 90.8 90 92 93 91.7 ' 91 92 91.5 // 91.2 +2.9 -53 51 54 52 52.5 88.0 +5.0 94.4 +5.5 94.9 +6..0 PEAK VELOCITY: METERS PER SECOND 50 52 . 50 51 50.8 58. 50 52 50 52,5 57 52 53 51 53.2 48 47 52 56 50.8 54 53 50 52 52.2 50 55 54 52 52.8 91.6 +1.1 48 53 52 51.0 50 53 51.5 52.5 +1.3 50.8 +2.8 52.4 +2,7 53.0 +2.3 51.2 +2.2 * Kept moist with Ringer's solution during dissection. TekWmiJ'^ f S.D, - Standard Deviation.. Uo v ^, /i1*4i DUP050043886 g TEST FOR EFFECT OF TREATMENT 00 vD 00 d\ co in CM H d o oo in vO ON CO CM 9- rH O H co in o> co c m on Mi* c m r>* o n c m co rs m <n cn rH o dodo * o d) co to co -H UP u0) 0 4J** SP5 <4 < pO HrH co u P rH ,<j- 44 55 pM CO K 00 H H CM ~H HH 41 r~i <t <1* <* Sf co m o\ m N CM In ti *H o HI vp <j- co9 Mi9- 41 41 r- si* co o m n co CM rH O VO IN vp !>, vp ^ 9-99999 CM CM CM CM CM CM -H 41 41 -H -H -H CM N CM CM N CM m m in in in in 4c # VO CM CO M3 CM CM: On <i* O'* O<tj vp sti P mS9f 9CO C0j vO lOj OOP CO -H a) > * to M fcO 44 p <tf O O rH H rH P< > M p P* co M o) 44 do p *H p -p d oP d 4J Td to o d -h oQ o oo 9 st tn 41 41 41 ON o rH NO IN. 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Constant Temperature Shelter With Stimulating and Recording Equipment. 1) Constant Temperature Shelter 2) Telethermometer ' , 3) Stimulus Isolation Unit 4) Recording Unit: amplifier and oscilloscope 5) Tektronix Stimulation Unit DUP050043888 ci ul DUP050043889 FIGURE 2. Large Electrode Set S2: stimulating electrodes R: recording electrodes The connection between S2 and the nearest recording electrode, R, is a ground connection. DUP050043890 DUP050043891 I FIGURE 3. . Tracing, from photograph, of compound action potentials recorded on oscilloscope screen. Lower Tracing: action potentials recorded as impulses arrive at recording electrode 2.48 cm. from stimulating electrode, S2. Upper Tracing: action potentials recorded as these same impulses arrive at the recording electrode 4.48 cm. from 8 . A: Stimulus Artifact 1 Is Time Interval between stimulation of nerve at S2 and the arrival of the most rapidly conducted impulses at the recording electrode 2.48 cm. from S?, the "inflection". 2: Time Interval between stimulation of nerve at S2 and the arrival of impulses over the largest number of similar nerves at the same recording electrode, the "peak". DUP050043892 DUP050043893