- Email: [email protected]
MONOCULAR OCCLUSION IN DYSLEXIC CHILDREN
728 LISTERIOSIS
SIR,-Your Aug 17 editorial comments that no specific culture medium for Listeria is available. I have found that one of the media used for the isolation of Gardnerella vaginalis acts as a semiselective medium for Listeria-an apposite combination of features for those searching for genital pathogens. The medium is Columbia colistinnalidixic human blood agar plus which, in this laboratory, is routinely incubated in 90% H2 plus 10% CO2 for 48 h. L monocytogenes appears, under these conditions, as small 0-haemolytic colonies about twice the size of those of G vaginalis. When left in air at room temperature for 24-48 h the Listeria colonies enlarge and become white and easily recognisable. When tested in parallel with horse blood agar, there is no inhibition of the growth of Listeria. When mixed with a suspension of faeces (as a gross challenge) Listeria grew well and obviously when incubated anaerobically as above, the medium inhibiting most of the faecal flora. The colonies of Listeria were even more obvious after the plates had been left on the bench at room temperature overnight. This medium therefore offers the advantage of being semiselective for two potential pathogens and the simple routine of leaving plates on the bench at room temperature for 1-2 days after Gardnerella colonies have been subcultured should enable Listeria to be detected. A more detailed report will appear elsewhere.
amphotericin,
Department of Laboratory Medicine, Ruchill Hospital, Glasgow G20 9NB 1. Spiegel CA, bacteria
in
R. J FALLON
Amsel R, Eschenbach D, Schoenknecht F, Holmes KK Anaerobic non-specific vaginitis N Engl J Med 1980; 303: 601-07.
SiR,-Your editorial perpetuates the myth that Dr J. H. H. Pirie
named the genus Listeria for his chief, Sir Spencer Lister.’ In his original report, however, Pirie wrote: "I propose ... the generic name, Listerella, dedicating it in honour of Lord Lister, one of the most distinguished of those connected with bacteriology whose name has not been commemorated in bacteriological nomenclature".2This is an obvious reference to Joseph Lister (1872-1912), father of antiseptic surgery. Later Pirie was obliged to rename the genus Listeria, because "Listerella" had already been used for a genus of mycetozoan.3 Department of Microbiology, University of Melbourne,
R. M. ROBINS-BROWNE
Parkville, Victoria 3052, Australia
EJ, Sierra MF Listeria monocytogenes: Another look at the "Cinderella among pathogenic bacteria" Mt Sinai J Med 1977; 44: 42-59. 2 Pirie JHH A new disease of veld rodents. "Tiger River disease" Publ S Afr Inst Med Res 1927, 3: 163-86 3 Pirie JHH Listeria: Change of name for a genus of bacteria. Nature 1940, 145: 264. 1 Bottone
MONOCULAR OCCLUSION IN DYSLEXIC CHILDREN
reading difficulties is full of about cerebral dominance and eye movement disorders, but the study described by J. Stein and S. Fowler (July 13, p 69) was carefully planned and executed. If the findings are confirmed, the demand for orthoptic services will increase, for reading difficulties are common and cause much anxiety. It is therefore essential to exclude as far as possible other explanations for Stein and Fowler’s results. The main problem in any education intervention experiment is to distinguish between the specific effects of the technique being tested and the more general effects of taking an interest in the child’s progress (the educational equivalent of a placebo response). A child’s reading improves substantially if a parent regularly listens to him reading.’ Even if we accept that "unfixed reference" correlates with poor reading and that a "fixed reference eye" can be achieved by occlusion, another explanation for Stein and Fowler’s results is possible. We are told that the trial was double-blind, but clearly it was not, since the parent and child knew whether or not the spectacles had one opaque lens. It seems likely that parents with a child in the occlusion group would regard the spectacles as SIR,-Published work
unsubstantiated
,
on
hypotheses
"treatment" and would insist that the child should do some reading practice while wearing them, resulting in the progress predicted by the study mentioned previously.1 Conversely, parents whose child was allocated plain spectacles would be less motivated to insist on their use. Two points favour this interpretation. Firstly, 20 children were lost to follow-up. There appeared to be 61 children in the occlusion group, but only 40 in the unoccluded group; were the 20 defaulters all disillusioned parents who had hoped for allocation to the occlusion group? I cannot otherwise account for the discrepancy in the size of the groups. Secondly, the 10 unoccluded children who developed fixed reference did not make significant progress in the first 6 months. This again might suggest that it is not the development of fixed reference itself which led to reading progress, but some associated factor. The delayed improvement in this group is difficult to explain either by Stein and Fowler’s hypothesis or by the alternative suggested here. Conceivably, learning that reference had become fixed might itself have an encouraging placebo effect. This study should be repeated, using a placebo treatment that carries more conviction than plain spectacles, so that this source of bias can be eliminated. Health authorities need this information as soon as possible, so that they can decide whether an expansion in the orthoptist establishment will be needed. Department of Child Health, St George’s Hospital Medical School, London SW17 0RE
D.M.B.HALL
J, Schofield WN, Hewison J. Collaboration between teachers and parents in assisting children’s reading. Br J Educ Psychol 1982; 52: 1-15.
1. Tizard
VITAMIN K DEFICIENCY IN THE NEWBORN
SiR,—Measurement of prothrombin percursor proteins induced by vitamin K absence (PIVKA II) using Dr Motohara and colleagues’ new sensitive method! offers a promising tool for the evaluation of vitamin K deficiency in the newborn. Their data (Aug 3, p 242), however, raise questions about the specificity of the test and the design of the study. PIVKA II was detected in 19.607o of the cord blood samples of babies randomised to vitamin K prophylaxis. Despite a huge dose of 5 mg vitamin K2 administered orally PIVKA II persisted in 11 .4% of the babies on day 5, remaining in the same range as in cord blood. These data suggest that oral vitamin K2 is ineffective in nearly 60% of babies, despite the well-known low neonatal vitamin K requirement. Motohara standardised his method! on adult and infant plasma, without comparing his test with conventional
PIVKA II assays. The method’s specificity for vitamin-Kdeficiency induced changes of the prothrombin molecule in the neonatal period has yet to be established. Motohara et al provide only a vague description on the infants’ feeding ("mostly breastfed"). However, the onset of feeding and the kind of milk significantly influence the incidence of hypoprothrombinaemia in babies.2,3 A similar effect on the detection rate of PIVKA II can be anticipated, though it has not been reported so far. We have used crossed immunoelectrophoresis to detect PIVKA II 4 and have modified the assay for plasma in the newborn. were unable to detect PIVKA Using this method we, like II in 40 cord blood samples. When we applied this method to plasma from 191 consecutive babies on the 5th and 6th day of life, who had not received vitamin K prophylaxis, we detected PIVKA II more frequently in those on breast feeding alone (88/162) or with formula (6/15) than in those on formula only (1/14). Since lactation takes some time to become established, most babies who were breastfed exclusively had their first milk feeds later (not before the third day of life in some) than those who received formula. The high detection rate of PIVKA II in babies receiving maternal milk and formula was unsuspected in our previous study3where all babies were given supplementary formula with the first feed if lactation was insufficient to meet the baby’s demand. Supplementary formula in babies with PIVKA II, however, had not been introduced before the 3rd day of life, when it became evident that the mother’s milk production was insufficient. A baby’s vitamin K supply depends on the vitamin K content of the milk and on the amount of milk given. The vitamin K content of
others,capillary ,6
SIR,-Your Aug 17 editorial comments that no specific culture medium for Listeria is available. I have found that one of the media used for the isolation of Gardnerella vaginalis acts as a semiselective medium for Listeria-an apposite combination of features for those searching for genital pathogens. The medium is Columbia colistinnalidixic human blood agar plus which, in this laboratory, is routinely incubated in 90% H2 plus 10% CO2 for 48 h. L monocytogenes appears, under these conditions, as small 0-haemolytic colonies about twice the size of those of G vaginalis. When left in air at room temperature for 24-48 h the Listeria colonies enlarge and become white and easily recognisable. When tested in parallel with horse blood agar, there is no inhibition of the growth of Listeria. When mixed with a suspension of faeces (as a gross challenge) Listeria grew well and obviously when incubated anaerobically as above, the medium inhibiting most of the faecal flora. The colonies of Listeria were even more obvious after the plates had been left on the bench at room temperature overnight. This medium therefore offers the advantage of being semiselective for two potential pathogens and the simple routine of leaving plates on the bench at room temperature for 1-2 days after Gardnerella colonies have been subcultured should enable Listeria to be detected. A more detailed report will appear elsewhere.
amphotericin,
Department of Laboratory Medicine, Ruchill Hospital, Glasgow G20 9NB 1. Spiegel CA, bacteria
in
R. J FALLON
Amsel R, Eschenbach D, Schoenknecht F, Holmes KK Anaerobic non-specific vaginitis N Engl J Med 1980; 303: 601-07.
SiR,-Your editorial perpetuates the myth that Dr J. H. H. Pirie
named the genus Listeria for his chief, Sir Spencer Lister.’ In his original report, however, Pirie wrote: "I propose ... the generic name, Listerella, dedicating it in honour of Lord Lister, one of the most distinguished of those connected with bacteriology whose name has not been commemorated in bacteriological nomenclature".2This is an obvious reference to Joseph Lister (1872-1912), father of antiseptic surgery. Later Pirie was obliged to rename the genus Listeria, because "Listerella" had already been used for a genus of mycetozoan.3 Department of Microbiology, University of Melbourne,
R. M. ROBINS-BROWNE
Parkville, Victoria 3052, Australia
EJ, Sierra MF Listeria monocytogenes: Another look at the "Cinderella among pathogenic bacteria" Mt Sinai J Med 1977; 44: 42-59. 2 Pirie JHH A new disease of veld rodents. "Tiger River disease" Publ S Afr Inst Med Res 1927, 3: 163-86 3 Pirie JHH Listeria: Change of name for a genus of bacteria. Nature 1940, 145: 264. 1 Bottone
MONOCULAR OCCLUSION IN DYSLEXIC CHILDREN
reading difficulties is full of about cerebral dominance and eye movement disorders, but the study described by J. Stein and S. Fowler (July 13, p 69) was carefully planned and executed. If the findings are confirmed, the demand for orthoptic services will increase, for reading difficulties are common and cause much anxiety. It is therefore essential to exclude as far as possible other explanations for Stein and Fowler’s results. The main problem in any education intervention experiment is to distinguish between the specific effects of the technique being tested and the more general effects of taking an interest in the child’s progress (the educational equivalent of a placebo response). A child’s reading improves substantially if a parent regularly listens to him reading.’ Even if we accept that "unfixed reference" correlates with poor reading and that a "fixed reference eye" can be achieved by occlusion, another explanation for Stein and Fowler’s results is possible. We are told that the trial was double-blind, but clearly it was not, since the parent and child knew whether or not the spectacles had one opaque lens. It seems likely that parents with a child in the occlusion group would regard the spectacles as SIR,-Published work
unsubstantiated
,
on
hypotheses
"treatment" and would insist that the child should do some reading practice while wearing them, resulting in the progress predicted by the study mentioned previously.1 Conversely, parents whose child was allocated plain spectacles would be less motivated to insist on their use. Two points favour this interpretation. Firstly, 20 children were lost to follow-up. There appeared to be 61 children in the occlusion group, but only 40 in the unoccluded group; were the 20 defaulters all disillusioned parents who had hoped for allocation to the occlusion group? I cannot otherwise account for the discrepancy in the size of the groups. Secondly, the 10 unoccluded children who developed fixed reference did not make significant progress in the first 6 months. This again might suggest that it is not the development of fixed reference itself which led to reading progress, but some associated factor. The delayed improvement in this group is difficult to explain either by Stein and Fowler’s hypothesis or by the alternative suggested here. Conceivably, learning that reference had become fixed might itself have an encouraging placebo effect. This study should be repeated, using a placebo treatment that carries more conviction than plain spectacles, so that this source of bias can be eliminated. Health authorities need this information as soon as possible, so that they can decide whether an expansion in the orthoptist establishment will be needed. Department of Child Health, St George’s Hospital Medical School, London SW17 0RE
D.M.B.HALL
J, Schofield WN, Hewison J. Collaboration between teachers and parents in assisting children’s reading. Br J Educ Psychol 1982; 52: 1-15.
1. Tizard
VITAMIN K DEFICIENCY IN THE NEWBORN
SiR,—Measurement of prothrombin percursor proteins induced by vitamin K absence (PIVKA II) using Dr Motohara and colleagues’ new sensitive method! offers a promising tool for the evaluation of vitamin K deficiency in the newborn. Their data (Aug 3, p 242), however, raise questions about the specificity of the test and the design of the study. PIVKA II was detected in 19.607o of the cord blood samples of babies randomised to vitamin K prophylaxis. Despite a huge dose of 5 mg vitamin K2 administered orally PIVKA II persisted in 11 .4% of the babies on day 5, remaining in the same range as in cord blood. These data suggest that oral vitamin K2 is ineffective in nearly 60% of babies, despite the well-known low neonatal vitamin K requirement. Motohara standardised his method! on adult and infant plasma, without comparing his test with conventional
PIVKA II assays. The method’s specificity for vitamin-Kdeficiency induced changes of the prothrombin molecule in the neonatal period has yet to be established. Motohara et al provide only a vague description on the infants’ feeding ("mostly breastfed"). However, the onset of feeding and the kind of milk significantly influence the incidence of hypoprothrombinaemia in babies.2,3 A similar effect on the detection rate of PIVKA II can be anticipated, though it has not been reported so far. We have used crossed immunoelectrophoresis to detect PIVKA II 4 and have modified the assay for plasma in the newborn. were unable to detect PIVKA Using this method we, like II in 40 cord blood samples. When we applied this method to plasma from 191 consecutive babies on the 5th and 6th day of life, who had not received vitamin K prophylaxis, we detected PIVKA II more frequently in those on breast feeding alone (88/162) or with formula (6/15) than in those on formula only (1/14). Since lactation takes some time to become established, most babies who were breastfed exclusively had their first milk feeds later (not before the third day of life in some) than those who received formula. The high detection rate of PIVKA II in babies receiving maternal milk and formula was unsuspected in our previous study3where all babies were given supplementary formula with the first feed if lactation was insufficient to meet the baby’s demand. Supplementary formula in babies with PIVKA II, however, had not been introduced before the 3rd day of life, when it became evident that the mother’s milk production was insufficient. A baby’s vitamin K supply depends on the vitamin K content of the milk and on the amount of milk given. The vitamin K content of
others,capillary ,6