- Email: [email protected]
A Note on a New, Versatile, Photoelectric Cell Drop Counter*
July 1958
SCIENTIFIC EDITION
The leukocidal concentrations of the disinfectants tested are listed in column 3, and the maximum tested concentration of the compound permitting phagocytosis is likewise indicated. Again it should be pointed out that were determinations made in the ffap between these two values, the leukocidal point would probably shift in certain cases. Column 5 indicates the bactericidal/leukocidal ratio of each of the compounds tested. Theoretically as with all toxicity indexes, the lower the ratio, the safer the compound for routine use as a wound disinfectant. The relatively high value obtained for iodine tincture contrasts sharply. with the lack of cellular toxicity previously reported (13),and the result for Clorox does not bear’out previous reports of high leukocyte sensitivity to chlorine compounds (12). As the results indicate, only gentian violet, Clorox, and Isodine are less toxic to white blood cells than to bacteria, while classic disinfecta n t substances such as phenol and mercuric chloride evidence inordinate leukocide properties. However, the limitations of this and other toxicity studies must be carefully identified. Under practical conditions of disinfection, there is little doubt that phenol is effective, despite its evident cellular toxicity. Moreover, it would appear quite unlikely that the local destruction of phagocytic cells in a wound will long affect the healing process, since for all practical purposes the body’s stipply of leukocytes is unending. I t has even been shown (15) that the presence of mercuric chloride may actually raise rather than lower the ability of phagocytes t o engulf bacteria. Thus, the technique described here is not a substitute for clinical evaluation nor an infallible guide to the selection of nontoxic disinfectants. It is rather to be regarded as a simplified and rapid method for obtaining one small part of the profile of potential disinfectant agents; in
533
the final analysis, it is the entire profile on which the use or non-use of the compxmd tested must be based.
SUMMARY
1. .4 rapid and simplified modification of earlier techniques for the comparison of bactericidal and leukocidal values of wound disinfectants has been described. 2. -‘Under the test conditions, only gentian violet, Clorox, a n d Isodine, of the disinfectants tested, are less toxic to leukocytes than to bacteria. 3. . The limitations on the use and significance of the test procedure have been discussed. REFERENCES (1) Nungester, W. J.. and Kempf, A. H., J . Znfccfious Discuses, 71, 174(1942). (2) Sarber. R. W.. J . Phormocol. E x b f l . Therob.. 75. 27711Q42). ’ (3) Green, T.W., and Birkeland, J. M., 1.Infccfious DisI ~ W F, 74.32119441 . -,_- .- ..,. (4) Salle, A. J.. and Lazarus, A. S . , P r o c . Soc. E x p f l . B i d . Mcd., 32,665(1935). (5) Salle,, A. J.. M a m i e , W. A,, and Schechmeister, I . L.. J . Bocfcrrol., 34, 2670937). (6) Salle, A . J., McOmie, W. A,,, Schechmeister. I . L., and Foord D . C. Proc. Soc. Expfl. Baol. Mcd. 37 694(1938). ( 7 ) Salie A. A p p l . Microbiol. 3 63(1955)’. (8)Birkhaug. K . E., J . A m . M c i . h o c . , 95. 917(1930). (9) Lambert, R. A., and Meyer, J. R., Proc. Soc. E x p f I . Biol. Mcd., 23, 4290926). (10) Bucksbaum, R., and Bloom, W., Proc. SOL. E x p f l . Biol. Mcd., 28,1060(1931). (11) Bronfenhrenner, J., Hershey, A. D., and Doubly, J.. Proc. Soc. Exfill. Biol. Mcd., 38, 210(1938). (12) Nye, N. R.. J . A m . Mcd. Assoc.. 108. 280(1937). (13) Welch, H.. and Hunter, A. C., A m . J . Public H c o l f k , 30,129(1940). (14) Welch, H., Slocum, G. G., and Hunter, A. C., J . Lob. Clin. Mcd., 27,1432(1942). (15) Lambin, S . , and Desvignes, A,, Compf. rend. soc. biol., 146,1920(1952). _
_____
I
~
.
i.
Notes A Note on a New, Versatile, Photoelectric Cell Drop Counter* By RICHARD F. CHILDS and ALBERT L. PICCHIONI
T
for an efficient, inexpensive, drop counter is frequently encountered in the laboratory. Although many instruments designed to count drops have been reported, the majority of them when used are limited with respect to such factors as rate HE NEED
* Received January 14, 1958, from the College of Pharmacy, University of Arizona, Tucson. Presented at the Section on Pharmacy, A.A.A.S., Indianapolis meeting, December, 1957.
of falling drops, viscosity, and electrolyte content of the fluid. The photoelectric cell counter, such as that employed with chromatographic fraction collectors, does not possess these limitations; however, commercially available productions are expensive. In addition, it has been the experience of one of the authors that some of these counters require considerable adjustment before and during use in order t o
534
JOURNAL OF THE
AMERICANPHARMACEUTICAL ASSOCIATION Vol. XLVII, No. 7
insure that the drops fall directly into the light beam impinging on the photocell. Through the use of a n inexpensive, miniature, transistor photodiode, and a new principle for activating this photocell, a n economical, highly efficient drop counter has been produced. The instrument consists of two separate units-the “Sensor” and “Recorder.” As illustrated in Fig. 1, the former is comprised of a cadmium sulfide photodiode, a glass dropper tube, and oblique and frontal light sources consisting of %volt flashlight bulbs each of which is coated in such a manner as t o form a small slit yielding a narrow beam of light. The oblique light beam is directed at a 60” angle t o strike beneath the photocell. When the parallel light source is used, the light beam is intentionally made to strike the small photodiode window. The Recorder unit
8CNSOR UNIT
R-1 of the Recorder unit. The starter anode (grid) of VT-1 in the Recorder unit obtains its voltage from a voltage divider comprised of R-2, the photodiode, and R-4. When the window of thc photodiode is dark, the resistance of the voltage divider is high and the starter anode voltage too low to allow VT-1 to draw plate current. When light strikes the window, however, the resistance of the photodiode drops, thereby increasing the voltage across R-4. A t this time VT-1 conducts plate current through the springloaded relay counter. Occasionally, it is necessary to count drops of an opaque liquid. In such cases, the frontal light source is selected by adjusting SW-2 of the recorder unit. An opaque drop falling from the glass tube interrupts the light beam directed into the window of the photodiode causing a marked light intensity differential which activates the cell.
RECORDER
TRANSFORYER THOROARSON
FRONTAL LlQYT
SENSOR UNIT
Fig. 1.-Sketch illustrating relationship of elements of the Sensor unit on the left and schematic diagram for the complete photoelectric cell drop counter, including the Sensor and Recorder units, on the right.
consists essentially of a R.C.A. No. 5823 cold cathode thyratron tube (VT-1) and a Mercury 110 volt a.-c. relay counter, which has been modified by attaching a Walsaco No. 7400F dial drive spring to the ratchet arm t o facilitate operation of the counter directly from the plate current of VT-1. By referring to Fig. 1, the principle of operation of both units of the drop counter can be explained. When a transparent or translucent liquid drops from the glass tube in the Sensor unit, light rays from the oblique light beam pass through each drop and are refracted. The result is a magnified bright circle of light which sweeps the small photodiode window. This sharp contrast of lighting is very effective for activating the cell. The optimum oblique light intensity for a given liquid is calibrated by adjusting
A desirable feature of this instrument is the close proximity and permanent positioning of the components of the Sensor unit (Fig. 1). Such a n arrangement obviates the need for repeated adjustments before and during use of the drop counter. The Sensor unit is also designed so that the drops may be collected in a graduate for volume measurements if desired. Further, the instrument is applicable for measuring fluid inflow, since the drops passing through the Sensor unit are neither mechanically damaged nor chemically contaminated. The drop counter is capable of accurately recording drops of liquids at rates varying from 0 to 700 per minute. The authors have found the instrument very satisfactory for determining the rate of perfusate flow in such studies as coronary perfusion of the Langendorff heart preparation.
SCIENTIFIC EDITION
The leukocidal concentrations of the disinfectants tested are listed in column 3, and the maximum tested concentration of the compound permitting phagocytosis is likewise indicated. Again it should be pointed out that were determinations made in the ffap between these two values, the leukocidal point would probably shift in certain cases. Column 5 indicates the bactericidal/leukocidal ratio of each of the compounds tested. Theoretically as with all toxicity indexes, the lower the ratio, the safer the compound for routine use as a wound disinfectant. The relatively high value obtained for iodine tincture contrasts sharply. with the lack of cellular toxicity previously reported (13),and the result for Clorox does not bear’out previous reports of high leukocyte sensitivity to chlorine compounds (12). As the results indicate, only gentian violet, Clorox, and Isodine are less toxic to white blood cells than to bacteria, while classic disinfecta n t substances such as phenol and mercuric chloride evidence inordinate leukocide properties. However, the limitations of this and other toxicity studies must be carefully identified. Under practical conditions of disinfection, there is little doubt that phenol is effective, despite its evident cellular toxicity. Moreover, it would appear quite unlikely that the local destruction of phagocytic cells in a wound will long affect the healing process, since for all practical purposes the body’s stipply of leukocytes is unending. I t has even been shown (15) that the presence of mercuric chloride may actually raise rather than lower the ability of phagocytes t o engulf bacteria. Thus, the technique described here is not a substitute for clinical evaluation nor an infallible guide to the selection of nontoxic disinfectants. It is rather to be regarded as a simplified and rapid method for obtaining one small part of the profile of potential disinfectant agents; in
533
the final analysis, it is the entire profile on which the use or non-use of the compxmd tested must be based.
SUMMARY
1. .4 rapid and simplified modification of earlier techniques for the comparison of bactericidal and leukocidal values of wound disinfectants has been described. 2. -‘Under the test conditions, only gentian violet, Clorox, a n d Isodine, of the disinfectants tested, are less toxic to leukocytes than to bacteria. 3. . The limitations on the use and significance of the test procedure have been discussed. REFERENCES (1) Nungester, W. J.. and Kempf, A. H., J . Znfccfious Discuses, 71, 174(1942). (2) Sarber. R. W.. J . Phormocol. E x b f l . Therob.. 75. 27711Q42). ’ (3) Green, T.W., and Birkeland, J. M., 1.Infccfious DisI ~ W F, 74.32119441 . -,_- .- ..,. (4) Salle, A. J.. and Lazarus, A. S . , P r o c . Soc. E x p f l . B i d . Mcd., 32,665(1935). (5) Salle,, A. J.. M a m i e , W. A,, and Schechmeister, I . L.. J . Bocfcrrol., 34, 2670937). (6) Salle, A . J., McOmie, W. A,,, Schechmeister. I . L., and Foord D . C. Proc. Soc. Expfl. Baol. Mcd. 37 694(1938). ( 7 ) Salie A. A p p l . Microbiol. 3 63(1955)’. (8)Birkhaug. K . E., J . A m . M c i . h o c . , 95. 917(1930). (9) Lambert, R. A., and Meyer, J. R., Proc. Soc. E x p f I . Biol. Mcd., 23, 4290926). (10) Bucksbaum, R., and Bloom, W., Proc. SOL. E x p f l . Biol. Mcd., 28,1060(1931). (11) Bronfenhrenner, J., Hershey, A. D., and Doubly, J.. Proc. Soc. Exfill. Biol. Mcd., 38, 210(1938). (12) Nye, N. R.. J . A m . Mcd. Assoc.. 108. 280(1937). (13) Welch, H.. and Hunter, A. C., A m . J . Public H c o l f k , 30,129(1940). (14) Welch, H., Slocum, G. G., and Hunter, A. C., J . Lob. Clin. Mcd., 27,1432(1942). (15) Lambin, S . , and Desvignes, A,, Compf. rend. soc. biol., 146,1920(1952). _
_____
I
~
.
i.
Notes A Note on a New, Versatile, Photoelectric Cell Drop Counter* By RICHARD F. CHILDS and ALBERT L. PICCHIONI
T
for an efficient, inexpensive, drop counter is frequently encountered in the laboratory. Although many instruments designed to count drops have been reported, the majority of them when used are limited with respect to such factors as rate HE NEED
* Received January 14, 1958, from the College of Pharmacy, University of Arizona, Tucson. Presented at the Section on Pharmacy, A.A.A.S., Indianapolis meeting, December, 1957.
of falling drops, viscosity, and electrolyte content of the fluid. The photoelectric cell counter, such as that employed with chromatographic fraction collectors, does not possess these limitations; however, commercially available productions are expensive. In addition, it has been the experience of one of the authors that some of these counters require considerable adjustment before and during use in order t o
534
JOURNAL OF THE
AMERICANPHARMACEUTICAL ASSOCIATION Vol. XLVII, No. 7
insure that the drops fall directly into the light beam impinging on the photocell. Through the use of a n inexpensive, miniature, transistor photodiode, and a new principle for activating this photocell, a n economical, highly efficient drop counter has been produced. The instrument consists of two separate units-the “Sensor” and “Recorder.” As illustrated in Fig. 1, the former is comprised of a cadmium sulfide photodiode, a glass dropper tube, and oblique and frontal light sources consisting of %volt flashlight bulbs each of which is coated in such a manner as t o form a small slit yielding a narrow beam of light. The oblique light beam is directed at a 60” angle t o strike beneath the photocell. When the parallel light source is used, the light beam is intentionally made to strike the small photodiode window. The Recorder unit
8CNSOR UNIT
R-1 of the Recorder unit. The starter anode (grid) of VT-1 in the Recorder unit obtains its voltage from a voltage divider comprised of R-2, the photodiode, and R-4. When the window of thc photodiode is dark, the resistance of the voltage divider is high and the starter anode voltage too low to allow VT-1 to draw plate current. When light strikes the window, however, the resistance of the photodiode drops, thereby increasing the voltage across R-4. A t this time VT-1 conducts plate current through the springloaded relay counter. Occasionally, it is necessary to count drops of an opaque liquid. In such cases, the frontal light source is selected by adjusting SW-2 of the recorder unit. An opaque drop falling from the glass tube interrupts the light beam directed into the window of the photodiode causing a marked light intensity differential which activates the cell.
RECORDER
TRANSFORYER THOROARSON
FRONTAL LlQYT
SENSOR UNIT
Fig. 1.-Sketch illustrating relationship of elements of the Sensor unit on the left and schematic diagram for the complete photoelectric cell drop counter, including the Sensor and Recorder units, on the right.
consists essentially of a R.C.A. No. 5823 cold cathode thyratron tube (VT-1) and a Mercury 110 volt a.-c. relay counter, which has been modified by attaching a Walsaco No. 7400F dial drive spring to the ratchet arm t o facilitate operation of the counter directly from the plate current of VT-1. By referring to Fig. 1, the principle of operation of both units of the drop counter can be explained. When a transparent or translucent liquid drops from the glass tube in the Sensor unit, light rays from the oblique light beam pass through each drop and are refracted. The result is a magnified bright circle of light which sweeps the small photodiode window. This sharp contrast of lighting is very effective for activating the cell. The optimum oblique light intensity for a given liquid is calibrated by adjusting
A desirable feature of this instrument is the close proximity and permanent positioning of the components of the Sensor unit (Fig. 1). Such a n arrangement obviates the need for repeated adjustments before and during use of the drop counter. The Sensor unit is also designed so that the drops may be collected in a graduate for volume measurements if desired. Further, the instrument is applicable for measuring fluid inflow, since the drops passing through the Sensor unit are neither mechanically damaged nor chemically contaminated. The drop counter is capable of accurately recording drops of liquids at rates varying from 0 to 700 per minute. The authors have found the instrument very satisfactory for determining the rate of perfusate flow in such studies as coronary perfusion of the Langendorff heart preparation.