bluuebunny/crossref_metadata_2025_split huggingface dataset:
The titration of vaccinia virus by the pock counting technique
Authors: Kaplan C. , Belyavin G. 
Published: May 2009

Ninety-seven groups of five-membrane pock counts from 115 titrations of vaccinia virus preparations were examined in an attempt to identify the statistical distribution followed by such counts, and to obtain an estimate of the overall coefficient of variation of the technique.It was found that the distribution of counts was neither Poissonian nor normal, and that the count variances ‘wandered’ so extensively that no valid estimate of the overall coefficient of variation was possible. Nor was it possible to assess the intrinsic reproducibility of the test, although it is empirically a useful one.
Protection of mice by living Vi and O vaccines against death caused bySalmonella paratyphi C
Authors: Archer G. T. L. , Whitby J. L. 
Published: May 2009

In seeking a more satisfactory test than the conventional mouse-protection tests for the assessment of typhoid-paratyphoid vaccines in relation to their O and Vi antigens, it was decided to undertake a series of experiments with vaccines containing the somatic antigens ofSalmonella paratyphi Cand to use this organism to challenge mice thus immunized.Salm. paratyphi Ccontains the same Vi antigen asSalm. typhiand moreover it is capable of giving rise to a true infection in mice in contrast to the acute intoxication which follows a fatal dose ofSalm. typhi.Large doses, of the order of 100 × 106, of this paratyphoid organism injected intraperitoneally into mice resulted in acute intoxication with death in 24–72 hr., similar in every way to the picture with typhoid bacilli, but when the dose was reduced 100-fold or more an infective illness was set up which after an interval of 5–10 days or more, during which the organisms multiply freely in the tissues, terminated fatally. Typhoid bacilli do not produce a true infection in mice.Living vaccines were prepared ofSalm. typhiTy6S (an almost pure Vi strain) andSalm. cholerae-suis(contains the same O-antigen complex asSalm.paratyphi C). These were used separately, and in combination, to immunize different batches of mice by the subcutaneous route against a subsequent intraperitoneal challenge with a Vi-positive culture ofSalm. paratyphi Cat both high- and low-dose levels. The different challenge doses were to assess the relative values of the 0 and Vi components in protecting against intoxication (high dose) and infection (low dose), respectively.Against intoxication pure Vi vaccines were almost as effective as Vi + O vaccines, whereas pure O vaccines gave little or no protection.Against fatal infection the combined Vi + O vaccine offered good protection and the pure O vaccine was but little inferior, whereas the pure Vi vaccine appeared to be without significant effect.Quite small doses ofSalm. paratyphi Cadministered by the intra-gastric route can give rise to a general infection in mice, but in order to obtain consistent results much larger doses were found necessary (about 300 x 106organisms). Mice immunized with the same three vaccines and subsequently challenged by the intragastric route with this large dose showed significant protection throughout. The combined, O + Vi, vaccine did not appear to have any advantage over the pure O vaccine, but both were markedly superior to the pure Vi vaccine. Further experiments on the same lines are however necessary to see if the results obtained in this single experiment are reproducible.The relationship of the above findings to the evaluation of agents employed in man for the prophylaxis of enteric fever and the need for further experimental work of a similar nature are discussed.We wish to thank Dr F. Kauffmann for strains ofSalm. paratyphi C, Lt-Col. T. E. Field, whose results we have freely quoted, and Dr S. Peto for advice on statistical evaluation of our results.
Studies in the variability of pock counts
Authors: Armitage P. 
Published: May 2009

1. The relationship has been examined between the variance and the mean of pock counts made by a number of different workers.2. In all cases the variance was considerably greater than that expected if the distributions were of the Poisson form. Recent work of Westwoodet al.(1957) suggests that variation approaching the Poisson expectation can be achieved by appropriate technical measures.3. With one exception, there appeared to be a linear relationship between the logarithm of the variance and the logarithm of the mean. The slope of this line varied from one laboratory to another, but not, apparently, from one occasion to another in any one laboratory.4. The hypothesis that for any set of egg membranes the expectations of the pock counts bear constant ratios to each other, irrespective of the virus density, was untenable: the observed variances increase less rapidly with high counts than would have been expected on this theory.5. Statistical methods are proposed for comparing and combining sets of counts at different dilutions. If Poisson variability were achieved, simpler methods would be available.I am much indebted to Dr L. Collier, Prof. A. W. Downie, Dr C. Kaplan and Dr F. O. McCallum for permission to use their unpublished data; to Dr J. C. N. Westwood for discussing with me his (then) unpublished work; to Miss Irene Allen for computing assistance; and to Mrs G. M. Young for the preparation of the diagrams.
Streptococcal infections among children in a residential home: II. Potential sources of infection for individuals
Authors: Holmes Margaret C. , Williams R. E. O. , Bloom C. V. , Hirch Ann , Lermit Ann , Woods Eileen 
Published: May 2009

1. For each case of streptococcal illness—sore throat, otitis, or other respiratory tract illness—observed in a 30-month study in a large children's home an attempt was made to enumerate the infected contacts from whom the infection might have been derived.2. Of 459 illnesses, 10·5% seemed to be relapses of a previous illness, and in 10·0% the child was known to have been carrying streptococci for more than 7 days before sickening, so that the causal relation of the streptococcus is in doubt.3. Of the 365 other illnesses, 31·5% could be attributed with varying degrees of confidence to infection from one specified carrier, 36·8% could have been derived from one or more recognized contacts although there was not sufficient evidence to specify one in particular. For 17·5% no infected contacts were recognized, but infection with the particular streptococcus was known to be present in the community; and for 9·3% there were no contacts and the streptococcus was not known to be present in the Village.4. Of the ninety-four illnesses for which the source could be specified as one particular carrier, 66% were derived from heavy nasal, 19% from light nasal, and 15% from throat carriers. Persons incubating a streptococcal illness and healthy carriers were each responsible for 31% of the illnesses and convalescent carriers for 38%.5. It seemed that at least 50% of all illnesses could have been contracted from contacts within the cottage; the proportion due to school infection was much more difficult to estimate but was at least 12%.
Determination of bacterial air pollution in various premises
Authors: Cvjetanović B. 
Published: May 2009

A simple method, applicable in routine work, for simultaneous air sampling of total bacteria, on serum agar, and Str. salivarius and Bact. coli on specific media, is described.Simultaneous air sampling including, in addition to detection of total bacteria, Str. salivarius and Bact. coli as indicators of buccal and faecal air-borne bacteria, respectively, reveals the kind and source of air-borne pollution much better than the simple total bacterial count.The air in various medical and public institutions was examined; the results are presented and discussed. The air pollution of the premises examined was relatively high, especially in the operating theatres. The air of infants' wards was found to be heavily polluted with Bact. coli as a result of poor nursing technique and this might have had bearing on the epidemic of infant diarrhoea.
Ringtail in new-born Norway rats. A study of the effect of environmental temperature and humidity on incidence
Authors: Totton Michael 
Published: May 2009

Ringtail in infant rats is shown to depend on humidity over a wide temperature range. It is not due to infection or diet, but probably to chronic cooling by evaporation, convection and conduction.Rats should either be bred in cages with solid floors, or else be given environmental conditions resembling those in the natural nest, which keep the young at a low saturation deficit during the early post-natal period.I am glad to express my thanks to M. Potter, Senior Animal Technician, for his invaluable aid in keeping the records of the experimental programmes, and to G. Dimmock for his help in building and maintaining apparatus. I am also grateful to the University of London for the loan of a Cambridge portable potentiometer.
Comparison of the infectivity of influenza Viruses in two host Systems: the Allantois of infect Eggs and Surviving Allantois-on-Shell
Authors: Groth S. Fazekas de St , White D. O. 
Published: May 2009

It is shown that the assay for infectivity in bits of allantois-on-shell, which has been standardized on the BEL strain, is optimal also for nine representative strains of influenza virus tested.On the average, the sensitivity of the technique is the same as of orthodox allantoic infectivity tests; its precision is always higher. The relative sensitivity of the two tests varies from strain to strain, the log tray/egg differences being SW (+0.88), MEL (+0.51), CAM (+0.31), PR8 (0.28), WSE (+0.25), HUT (−0.02), BEL (−0.22), FMI (−0.35), LEE (−0.47), BON (−1.02). This gradient is the same for fully infective and incomplete forms of influenza virus.The tray/egg gradient of susceptibility is negatively correlated with the variation in host resistance.The differences in susceptibility are not due to any effect of the plastic trays, to thermal inactivation of the virus, to differences in adsorption or viropexis in the two test systems or to the effect of allantoic fluid on the virus particle. The critical step has been shown to occur during the intracellular stage of multiplication.
The detection of cholera vibrios in Calcutta waters: the River Hooghly and canals
Authors: Abou-Gareeb A. H. 
Published: May 2009

1. Before undertaking a bacteriological survey of the waters of the Hooghly River and the associated canals a detailed epidemiological study over the past 20 years of cholera, as it affected the individual administrative wards of Calcutta, was undertaken. Sampling points were selected in accordance with the results of this study. Samples of water from the various points were collected at intervals extending from December 1958 to August 1959 in 2½–5 l. amounts. The whole sample in each case was filtered through special filter pads. The pads were first cultured in an enrichment medium from which plate cultures were subsequently made for colony isolation, serological and biochemical examination.2. The sampling points on the canals were all adjacent to areas where the local endemicity was judged to be high; other points were by bathing ghats, etc. A total of eighty-nine samples covering all the sampling points were examined and Vibrio cholerae were isolated from twelve of these samples, eight of which came from twenty-six samples collected from two sampling points on the Chetla and Circular Canals, respectively.3. The positive isolations were spread fairly evenly over the whole period of the study which covered both epidemic and non-epidemic periods including the monsoon. Although the incidence of cholera in Calcutta may fall to a low level during non-epidemic periods cases continue to occur throughout the year and the relationship of the maintenance of the infection in the city to the continuous potential infectivity of the open natural waters of Calcutta is discussed.
Heat labile and heat stable factors and antibodies in normal and immune sera against T-system bacteriophages
Authors: Çetin Enver Tall 
Published: May 2009

1. Heat labile and heat stable inactivating factors against T-system phages are present in normal guinea-pig and rabbit sera. These may be antibodies.2. Sera of guinea-pigs immunized with phages T2, T3and T4contain heat labile and heat stable antibodies.3. The heat labile activity is absorbed from guinea-pig serum by phage more readily than the heat stable activity.4. Dilution of the sera reduces the heat labile activity more than the heat stable activity.5. Complement has no effect on the inactivation or neutralization of phages T2, T3and T4by normal or immune guinea-pig sera.
Some properties of fluoracetamide as a rodenticide
Authors: Bentley E. W. , Greaves J. H. 
Published: May 2009

1. The average lethal dose of fluoracetamide for wild R. norvegicus was found to be 13 mg./kg. of body weight and the LD95, about 43 mg./kg.2. Wild rats offered bait contatining 0·5, 1 and 2% fluoracetamide, after a period of conditioning, seemed to find it palatable and, on the average, ingested the equivalent of 18–100 LD50's. Warning symptoms appeared in about an hour or longer and included short convulsive spasms.3. The speed of onset of warning symptoms leading to cessation of feeding was studied in albino rats dosed with the equivalent of 2 LD50's of sodium fluoracetate, zinc phosphide or fluoracetamide. Feeding ceased soonest in the case of sodium fluroacetate. Zinc phosphide gave very variable results, but it is thought that if wild rats had been used, feeding would have stopped nearly as soon as with sodium fluoracetate.4. It is considered that field trials to compare the efficiency of 1% flouracetamide and 2·5% zinc phosphide, both with ‘prebaiting’, would be well justified.5. Fluoracetamide at 2% may also prove to be a good alternative to 0·25% sodium fluoracetate as a ‘direct’ poison for controlling rats in sewers.We are indebted to Miss Y. Larthe and Miss E. J. Taylor who took part in the bioassay and in one of the experiments with the marked rats.
Observations on leptospiral antibodies occurring in pig sera
Authors: Davies M. Elizabeth 
Published: May 2009

A total of 849 samples of pig sera were tested for antibodies to L. canicola, L. icterohaemorrhagiae, L. pomona, L. ballum, L. sejroe, L. grippotyphosa, L. hyos (mitis Johnson), and L. bataviae. Positive results were obtained in 57 samples to all but the last three serotypes.I wish to thank Mr J. Norval of Edinburgh and Mr W. R. P. Hildebrand of Belfast for supplying the sera and Dr A. Wilson Taylor for his interest and supervision.I am greatly indebted to the late Dr J. C. Broom of the Wellcome Laboratories of Tropical Medicine for the supply of leptospira.
Heredity, infection and chemoprophylaxis in rheumatic carditis: an epidemiological study of a communal settlement
Authors: Davies A. Michael , Lazarov Eliahu 
Published: May 2009

1. Children and their parents in a communal settlement (kibbutz) were followed for 14 months with special regard to the influences of streptococcal carrier rate, streptococcal infections, chemotherapy and heredity on the pattern of rheumatic heart disease.2. Children with proven or probable heart disease showed the same streptococcal carrier rates as controls in spite of continued chemoprophylaxis with oral penicillin.3. A single injection of penicillin, given to all kibbutz members on the same occasion, reduced the streptococcal carrier and infection rates to zero and maintained a marked drop for 3 months. Thereafter, the rates rose to higher levels than before. Courses of sulphamethoxypyridazine (‘Lederkyn’) given first to the total population and then to children only, caused only temporary interruption in the attack rate.4. The prevalence of rheumatic heart disease in children of parents themselves affected was 2½ times greater than in controls exposed to the same environmental risks.5. Affected children were more susceptible to streptococcal infections than controls with identical exposure.Grateful thanks are due to Miss Pearl Weiskopf, B.Sc., for the statistical analysis. Without the close collaboration of Dr J. Yauluss, Nurses Tova and Ziva and the members of Kibbutz S this study would have been impossible. Thanks are also due to Lederle Laboratories Department of Cynamid International and their Israeli agent, Dr L. Goldshmidt, for the gift of ‘Lederkyn’, and to Mrs Rachel Kosh for help beyond the call of her secretarial duties.
Detection of bacterial antigens by means of sensitized guinea-pig ileum
Authors: Buckland F. E. 
Published: May 2009

Using a Dale organ bath and the ileum of passively sensitized guinea-pigs a specific sensitive reaction with as little as 1 μg./ml. of disintegrated whole cultures of various bacteria and 0·01 μg./ml. of purifiedSh. dysenteriaeandS. typhimuriumpolysaccharides was obtained.More detailed study showed that 1 μg./ml. ofSh. dysenteriaedegraded polysaccharide derived from the O antigen could be detected with consistency. Lower concentrations gave irregular results.My thanks are due to the David Bruce Laboratory for supplying the antisera and the bacterial suspensions, to Prof. W. T. J. Morgan of the Lister Institute of Preventive Medicine for the antibody nitrogen determinations, to Dr D. A. L. Davies of the Microbiological Research Establishment, Porton, for the antigen preparations and to Corporals G. Willis and P. Brown, R.A.F., for much careful work in day to day experiments.
The growth and death of wound bacteria in serum, exudate and slough
Authors: Colebrook Leonard , Lowbury E. J. L. , Hurst L. 
Published: May 2009

Six strains of Str. pyogenes and four strains of Staph. aureus were found to grow well from large or small inocula in fresh human serum; four strains of E. coli failed to grow from large inocula and were killed when the inocula were small. Ps. pyocyanea, Proteus and Str. viridans sometimes grew and sometimes failed to grow in fresh serum.In serum which had been treated with trypsin or heated at 56° C. for 1 hr. the Gram-negative bacilli grew readily, and growth was still better in serum which had been heated and then trypsinized. Heating at 56° C. and treatment with proteolytic enzymes were shown to destroy complement and to inactivate the bactericidal activity of fresh serum against a Shigella highly sensitive to the properdin system. It is suggested that these changes might be enough to explain the conversion of serum by proteolytic enzymes into a suitable medium for the growth of coliform bacilli. This change might be brought about by bacterial or leucocytic enzymes. Fibrinolytic serum from a cadaver was found to retain at least a part of its complement and bactericidal activity.Strains of E. coli, Ps. pyocyanea, Proteus, Staph. aureus and Str. pyogenes were tested for growth in burn slough suspension and blister fluid. In slough suspension all strains grew well, but the Gram-negative bacilli grew rather more vigorously than the Gram-positive cocci. In blister fluid E. coli was killed and other strains grew.These findings are discussed in relation to wound sepsis.
Zone electrophoresis of poliovirus partially inactivated by formaldehyde
Authors: Polson A. , Hampton J. W. F. , Deeks D. 
Published: May 2009

It was shown in this work that the electrophoretic mobility of the MEF1 strain of poliovirus was increased approximately 25% after interrupted inactivation with formaldehyde. This is in accordance with past observations on the behaviour of formaldehyde-treated proteins. The residual live virus had the same mobility as the ‘killed’ virus, thus indicating that the surfaces of all the virus particles have been affected to the same degree by the inactivating agent.Gel precipitin tests performed on the different samples obtained by zone electro-phoresis showed, in addition to the main antigen, the presence of a small amount of a second component of slightly higher mobility, and, as it occurs in the main fraction and the sample thereafter it probably has a slightly higher mobility than the main component.The antigenic properties of the different fractions as shown by the production of antibodies in guinea-pigs correspond with the presence of precipitating antigen in the samples in the region of highest antigen concentration. The faint antigenicities of the fractions obtained from the regions higher up in the zone electrophoresis column are due to small amounts of virus antigen similar to that found in the column on electrophoresis of untreated MEF1 virus, bearing in mind that the inactivated virus was concentrated approximately 2000 times for zone electrophoresis.
The sterilization of surgical rubber gloves and plastic tubing by means of ionizing radiation
Authors: Oliver R. , Tomlinson A. H. 
Published: May 2009

Threads were infected with the spores of four species of bacteria and put inside rubber gloves which were sealed into plastic bags and irradiated with electrons or gamma rays. A dose of 1·5 Mrad. killed approximately 99·99% of the spores of each species and a dose of 2·5 Mrad. appeared to give an adequate margin of safety for sterilization. Spores were similarly killed inside plastic tubing and within the lumen of hypodermic needles.The tensile strength of the gloves decreased with increasing doses of radiation so that the rough, solution-dipped gloves tested were significantly weaker after 8·0 Mrad., but the smooth gloves tested still complied with the British Standard after 30 Mrad. When vacuum-packed before irradiation, rough gloves were still satisfactory after 16 Mrad., and smooth gloves were apparently unaffected by 30 Mrad.; they could, therefore, be sterilized six and twelve times, respectively.Radiation gives dependable sterilization of rubber gloves, and the use of a sealed plastic package obviates subsequent contamination. The possibility of using disposable radiation-sterilized gloves is discussed, the use of a plastic radiation indicator suggested and the practical applications of radiation sterilization in the hospital considered.
Brucellosis in dairy herds—some applications of the milk ring test
Authors: Ferguson G. S. , Robertson A. 
Published: May 2009

1. It has been shown that cows infected with brucellosis of the udder can usually be detected by an application of a modified milk ring test, based on the finding that milks from infected cows, in addition to showing a high bulk MRT titre also show considerable quarter variations. The effects of adult vaccination with strain 19 vaccine on the MRT are reported; low bulk titres with uniformity between quarters, except at the beginning and end of lactation and immediately following vaccinations, were observed, thus making differentiation between vaccinated and infected cows possible.2. In a survey of raw milk samples from three areas in southern Scotland, 3·5, 5·3 and 9·0% of samples were shown to be infected with Br. abortus.