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TECHNIQUES OF VIRUS TYPING
233 This work relates
only
to dead
lungs
under artificial
conditions, and in the living body other factors might come into play. Nevertheless, these experiments have a
"
considerable interest in relation to respiratory physiology and pathology illustrate once
; and, perhaps again the difficulty
more
individual granules is essential, and can be assured by admixture of the starch with either 2% magnesium oxide or 3% magnesium carbonate ; the tissues tolerate " these two dispersal agents equally well. Tanning of the starch with epichlorohydrin renders the starch granules resistant to autoclaving, but does not affect either the tissue tolerance or the absorbability of the starch as long as it is well dispersed in fine particles. Clumps " of powder imbedded in tissue will produce more reaction and will be absorbed more slowly. The Lee et of al. included the by experiments heavy dusting bowel surfaces of animals with the starch powder ; and even with such gross contamination the reaction wasrelatively slight. Infection of the operation area would, however, greatly increase the foreign body reaction, and might produce unabsorbable adhesions. The conclusion is therefore that sterilisable starch approaches the ideal as a glove lubricant ; that it must be combined with a suitable dispersal agent ; and that the surgeon should adopt the simple precautions of washing his gloves just before approaching the operation field and of avoiding spilling deposits of powder through defects in the fingertips of his gloves.
important, they
of applying simple to biological and measurements concepts physical material. In any biological system so many influences interact with each other that it is often almost impossible to separate the effect of one of them for study. To call the lungs elastic, however satisfactory in everyday conversation, is clearly an over-simplification ; and such over-silnplifications can be dangerous.
TECHNIQUES OF VIRUS TYPING THE merits of different animal sera in typing strains of influenza virus have long been disputed. Workers in Australia, Holland, and this country have used mainly ferret sera ; while in the U.S.A. rabbit, fowl, and hamster sera have been preferred. With ferrets and hamsters the serum is taken after the animals have been infected with influenza virus, whereas the other sera The argument has are obtained after immunisation. been more than academic since epidemiological deductions based on results with ferret sera could not have been made with, for example, fowl sera. Hitherto the dispute has been mainly emotional with each laboratory ready to swear by its own results. Now Sampaiohas made a direct comparison between the different sera. He chose four strains of influenza virus ; one was a recently isolated A-prime strain, and the others were, serologically speaking, a brother, a first cousin, and a forty-second cousin. With all the sera tested the distant relative was easily spotted ; but the fine distinctions between the near relations were detected with ferret and hamster sera only. Sampaio’s work would appear to settle the argument-though if hard facts were to settle all arguments this would become a quieter and duller world.
ENZYMES AND TRACHEOTOMY not IT is easy to maintain a clear airway in patients who have respiratory paralysis due to poliomyelitis or who are unconscious during the treatment of meningitis and head injuries. Repeated aspiration of the pharynx and postural drainage are usually effective for the first day or two, but small quantities of material from the pharynx inevitably find their way into the trachea. So long as the antibiotics are fully effective this is of no clinical significance ; but when resistant organisms replace the normal flora of the nose and throat, infection spreadsinto the trachea.
Tracheotomy will prevent this complication, but it will not relieve it once the tracheal infection is established. The trachea and bronchi then become filled with exudate, and, unless free drainage is provided, deaths ABSORBABLE GLOVE POWDER results from a combination of asphyxia and bronchoSOME years ago it became clear that contamination of pneumonia. The exudate is mucoid at first, becomingan operation field by talcum powder from the surgeon’s and then mucoid again as the infection subgloves might give rise to serious after-effects.2 In women purulent sides. After tracheotomy it tends to dry into tenacious " a clean appendicectomy was occasionally followed by masses and crusts because it is exposed to air unmoistened sterility, owing to the reaction of the fallopian tubes to by passage through nose and throat. Crusting can talc granules picked up from the peritoneal cavity. be prevented by providing a fine mist of water probably Experimentally talc applied to the peritoneum gave rise or saline for the patient to breathe, but the exudate is to intraperitoneal adhesions and granulomata. Spilling still sufficiently viscid to reduce the airway. of talc glove powder in more superficial wounds also Enzymes will liquefy the exudate, and encouraginggave rise to non-healing granulomata. These findings clinical results have been reported 1 ; but they must be led surgeons to wash their gloves in a sterile solution chosen carefully, for enzyme action is highly specific. after putting them on, and to discard at once a glove with Three constit-Cients can be responsible for the viscidity any defect that might allow powder to escape. of a tracheal or bronchial exudate : (a) a fibrous gel of Since this danger was brought to light there has been a mucoprotein during the early and the late stages of an sustained search for an absorbable substitute for talc infection ; (b) fibres of deoxyribonucleoprotein when the as a glove lubricant ; and corn starch has been widely infection is fully established and the exudate purulent ; used.3 Lee and his colleagues4 at Cincinnati suggest and (c) fibrin, which is particularly prominent in diphthat the feeling of security with such powders has theria. Simple cytochemical tests are available for the resulted in some carelessness on the part of surgeons. identification of these constituents ; the enzyme should Being convinced that they now have a " fool-proof be selected accordingly and administered as an aerosol. powder, they no longer observe the precautions they A satisfactory fibrinolysin is available commercially, but once did against wound and peritoneal contamination. and specific mucinases are not. deoxyribonuclease pure Is this lack of caution justified ?2 Lee and his co-workers from ox pancreas is very Crystalline deoxyribonuclease have carried out a series of experiments, similar to those effective in liquefying purulent exudates,2 but the which proved the dangers of talc. From these they streptococcal nuclease accompanying streptokinase is conclude that under ideal conditions starch powder is concentrated for this purpose. Lyophirarely absorbed without ill effect. Nevertheless, until it is lised sufficiently acts rapidly on mucus in solucrystalline trypsin absorbed it is a foreign body and produces a foreign-body but on tion,3 only slowly mucoprotein gel. Until more reaction in the tissues. The intensity, duration, and and mucinases and deoxyribonucleases . specific pure reversibility of this reaction is influenced by many become available commercially, lyophilised crystalline variables. Complete dispersal of the powder into trypsin is probably the best enzyme to use. "
"
1. Sampaio, A. A. C. Bull. World Hlth Org. 1952, 6, 467. 2. See Lancet, 1947, ii, 430. 3. See Graham, J. D. P., Jenkins, M. E. Ibid, 1952, i, 590. 4. Lee. C. M. jun., Collins, W. T., Largen, T. L. Surg. Gynec. Obstet. 1952. 95, 725.
1. Steigman, A. J., Scott, C. H. J. Amer. med. Ass. 1952, 150, 1403. 2. Armstrong, J. B., White, J. C. Lancet, 1950, ii, 739. 3. Limber, C. R., Reiser, H. G., Roettig, L. C., Curtis, G. M. J. Amer. med. Ass. 1952. 149, 816.
only
to dead
lungs
under artificial
conditions, and in the living body other factors might come into play. Nevertheless, these experiments have a
"
considerable interest in relation to respiratory physiology and pathology illustrate once
; and, perhaps again the difficulty
more
individual granules is essential, and can be assured by admixture of the starch with either 2% magnesium oxide or 3% magnesium carbonate ; the tissues tolerate " these two dispersal agents equally well. Tanning of the starch with epichlorohydrin renders the starch granules resistant to autoclaving, but does not affect either the tissue tolerance or the absorbability of the starch as long as it is well dispersed in fine particles. Clumps " of powder imbedded in tissue will produce more reaction and will be absorbed more slowly. The Lee et of al. included the by experiments heavy dusting bowel surfaces of animals with the starch powder ; and even with such gross contamination the reaction wasrelatively slight. Infection of the operation area would, however, greatly increase the foreign body reaction, and might produce unabsorbable adhesions. The conclusion is therefore that sterilisable starch approaches the ideal as a glove lubricant ; that it must be combined with a suitable dispersal agent ; and that the surgeon should adopt the simple precautions of washing his gloves just before approaching the operation field and of avoiding spilling deposits of powder through defects in the fingertips of his gloves.
important, they
of applying simple to biological and measurements concepts physical material. In any biological system so many influences interact with each other that it is often almost impossible to separate the effect of one of them for study. To call the lungs elastic, however satisfactory in everyday conversation, is clearly an over-simplification ; and such over-silnplifications can be dangerous.
TECHNIQUES OF VIRUS TYPING THE merits of different animal sera in typing strains of influenza virus have long been disputed. Workers in Australia, Holland, and this country have used mainly ferret sera ; while in the U.S.A. rabbit, fowl, and hamster sera have been preferred. With ferrets and hamsters the serum is taken after the animals have been infected with influenza virus, whereas the other sera The argument has are obtained after immunisation. been more than academic since epidemiological deductions based on results with ferret sera could not have been made with, for example, fowl sera. Hitherto the dispute has been mainly emotional with each laboratory ready to swear by its own results. Now Sampaiohas made a direct comparison between the different sera. He chose four strains of influenza virus ; one was a recently isolated A-prime strain, and the others were, serologically speaking, a brother, a first cousin, and a forty-second cousin. With all the sera tested the distant relative was easily spotted ; but the fine distinctions between the near relations were detected with ferret and hamster sera only. Sampaio’s work would appear to settle the argument-though if hard facts were to settle all arguments this would become a quieter and duller world.
ENZYMES AND TRACHEOTOMY not IT is easy to maintain a clear airway in patients who have respiratory paralysis due to poliomyelitis or who are unconscious during the treatment of meningitis and head injuries. Repeated aspiration of the pharynx and postural drainage are usually effective for the first day or two, but small quantities of material from the pharynx inevitably find their way into the trachea. So long as the antibiotics are fully effective this is of no clinical significance ; but when resistant organisms replace the normal flora of the nose and throat, infection spreadsinto the trachea.
Tracheotomy will prevent this complication, but it will not relieve it once the tracheal infection is established. The trachea and bronchi then become filled with exudate, and, unless free drainage is provided, deaths ABSORBABLE GLOVE POWDER results from a combination of asphyxia and bronchoSOME years ago it became clear that contamination of pneumonia. The exudate is mucoid at first, becomingan operation field by talcum powder from the surgeon’s and then mucoid again as the infection subgloves might give rise to serious after-effects.2 In women purulent sides. After tracheotomy it tends to dry into tenacious " a clean appendicectomy was occasionally followed by masses and crusts because it is exposed to air unmoistened sterility, owing to the reaction of the fallopian tubes to by passage through nose and throat. Crusting can talc granules picked up from the peritoneal cavity. be prevented by providing a fine mist of water probably Experimentally talc applied to the peritoneum gave rise or saline for the patient to breathe, but the exudate is to intraperitoneal adhesions and granulomata. Spilling still sufficiently viscid to reduce the airway. of talc glove powder in more superficial wounds also Enzymes will liquefy the exudate, and encouraginggave rise to non-healing granulomata. These findings clinical results have been reported 1 ; but they must be led surgeons to wash their gloves in a sterile solution chosen carefully, for enzyme action is highly specific. after putting them on, and to discard at once a glove with Three constit-Cients can be responsible for the viscidity any defect that might allow powder to escape. of a tracheal or bronchial exudate : (a) a fibrous gel of Since this danger was brought to light there has been a mucoprotein during the early and the late stages of an sustained search for an absorbable substitute for talc infection ; (b) fibres of deoxyribonucleoprotein when the as a glove lubricant ; and corn starch has been widely infection is fully established and the exudate purulent ; used.3 Lee and his colleagues4 at Cincinnati suggest and (c) fibrin, which is particularly prominent in diphthat the feeling of security with such powders has theria. Simple cytochemical tests are available for the resulted in some carelessness on the part of surgeons. identification of these constituents ; the enzyme should Being convinced that they now have a " fool-proof be selected accordingly and administered as an aerosol. powder, they no longer observe the precautions they A satisfactory fibrinolysin is available commercially, but once did against wound and peritoneal contamination. and specific mucinases are not. deoxyribonuclease pure Is this lack of caution justified ?2 Lee and his co-workers from ox pancreas is very Crystalline deoxyribonuclease have carried out a series of experiments, similar to those effective in liquefying purulent exudates,2 but the which proved the dangers of talc. From these they streptococcal nuclease accompanying streptokinase is conclude that under ideal conditions starch powder is concentrated for this purpose. Lyophirarely absorbed without ill effect. Nevertheless, until it is lised sufficiently acts rapidly on mucus in solucrystalline trypsin absorbed it is a foreign body and produces a foreign-body but on tion,3 only slowly mucoprotein gel. Until more reaction in the tissues. The intensity, duration, and and mucinases and deoxyribonucleases . specific pure reversibility of this reaction is influenced by many become available commercially, lyophilised crystalline variables. Complete dispersal of the powder into trypsin is probably the best enzyme to use. "
"
1. Sampaio, A. A. C. Bull. World Hlth Org. 1952, 6, 467. 2. See Lancet, 1947, ii, 430. 3. See Graham, J. D. P., Jenkins, M. E. Ibid, 1952, i, 590. 4. Lee. C. M. jun., Collins, W. T., Largen, T. L. Surg. Gynec. Obstet. 1952. 95, 725.
1. Steigman, A. J., Scott, C. H. J. Amer. med. Ass. 1952, 150, 1403. 2. Armstrong, J. B., White, J. C. Lancet, 1950, ii, 739. 3. Limber, C. R., Reiser, H. G., Roettig, L. C., Curtis, G. M. J. Amer. med. Ass. 1952. 149, 816.