A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors.

Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects. Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave, but owing to lack of observations this is uncertain. Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (±100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT = 4.185×10(12) joules). We show that a widely referenced technique of estimating airburst damage does not reproduce the observations, and that the mathematical relations based on the effects of nuclear weapons--almost always used with this technique--overestimate blast damage. This suggests that earlier damage estimates near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques. This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes.

The correlation between the numbers of some bacteria in human oral cavity and blood neutrophil count.

The correlation between the number of blood polymorphonuclear granulocytes (PMNs) and the counts of oral bacteria in 92 children (33 girls and 59 boys), aged 4-15 was investigated. The groups of children comprised 44 healthy individuals and 48 children suffering from acute lymphoblastic leukaemia who were given intensive antileukaemic chemotherapy. It was found that while the number of PMNs in blood decreased, the counts of Streptococcus spp., Staphylococcus spp., mutans streptococci, Lactobacillus spp., and Actinomyces spp. in the saliva tended to increase. The similar reciprocal correlation between the number of blood PMNs and the counts of these bacteria in the saliva was found in the group of healthy children. We concluded that the blood PMNs, by influencing the number of oral PMNs which control bacteria in this habitat, influence also the number of some groups of bacteria there.

[The presence of staphylococci in the vagina of pregnant women]. / Nosicielstwo gronkowców w pochwie kobiet ciezarnych.

We were investigating the colonisation rate as well as the quantity of staphylococci in the vagina of women with physiological and complicated pregnancy. We have found high frequency of staphylococci (coagulase-negative and/or coagulase-positive). Vaginal carriage rate amount 90%. According to our results neither the presence nor the quantity of these microorganisms were related to the presence or the number of lactobacilli, among them to the hydrogen peroxide producing ones. We have also assumed that neither colonisation nor the quantity of staphylococci have any influence on the course of pregnancy.

[Diseases caused by hantaviruses]. / Choroby wywolywane przez hantawirusy.

Hantaviruses are RNA viruses that belong to the genus Hantavirus, family Bunyaviridae. The main reservoir of hantaviruses are rodents. Humans become infected by inhaling particles of dust contaminated with faeces of rodents, that are found In Europe and Asia hantaviruses named: Hantaan, Seoul and Dobrava-Belgrade causing haemorrhagic fever with renal syndrome (HFRS) are prevalent. Typical clinical picture of HFRS consists of renal insufficiency (primarily anuria and then polyuria with disturbances of water and electrolytic balance), hypotension, shock and disseminated intravascular coagulation and fibrynolisis (DIC). The mild form of this disease caused by Puumala virus is found in Scandinavia. North and South America are the regions where the prevalence of viruses: Sin Nombre, Black Creek Canal, Bayou, and New York causing hantavirus pulmonary syndrome (HPS) has been noted. In the course of this disease non-cardiogenic pulmonary oedema requires immediate hospitalisation at intensive care ward with artificial ventilation. Mortality in HPS due to hypotension, hypoxia and shock ranges up to 40%.

[Staphylococci and enteric rods in the oral cavity of children with acute lymphoblastic leukemia]. / Gronkowce i paleczki jelitowe w jamie ustnej u dzieci z ostra bialaczka limfoblastyczna.

The frequency of isolation and the number of staphylococci and Gram-negative enteric rods in saliva were estimated in a group of 48 children of both sexes, aged 4-15 who were in the course of treatment of acute lymphoblastic leukemia (ALL). The results were compared with the same parameters in a group of 44 healthy children of the same age. Staphylococci (both coagulase-negative and coagulase-positive) were found in the oral cavities of all healthy children and of 91.6% children with ALL. However, the diseased children harbouring staphylococci revealed a significantly higher average number of these bacteria than healthy children; the respective values were 3.59 and 3.02 log CFU/ml of saliva (p = 0.0148). The average number of staphylococci in saliva was in both groups of children in negative correlation with the number of polymorphonuclear granulocytes in blood. Gram-negative enteric rods were present in the oral cavities of 13.6% of healthy children and 33.3% of children with ALL (p = 0.0005), but the counts of these bacteria were comparable. The negative correlation between the number of these bacteria and the number of polymorphonuclear granulocytes in blood was not significant.

[Some factors influencing the number of staphylococci in the mouth and throat of children]. / Niektóre czynniki wplywajace na liczebnosc gronkowców w jamie ustnej i w gardle u dzieci.

The relationship between the count of polymorphonuclear granulocytes in blood and also between the percentage of oral and pharyngeal streptococci showing antagonistic activity on the indicator strain Staphylococcus aureus 209P and the number of staphylococci in the oral cavity and pharynx were investigated. The study comprised 92 children, of both sexes, aged 4-15; among them there were 48 children with the decreased number of circulating polymorphonuclear granulocytes due to the treatment of acute lymphoblastic leukaemia (ALL). A statistically significant negative correlation between the number of polymorphonuclear granulocytes in blood and the count of oral and pharyngeal staphylococci (both coagulase-negative and coagulase-positive) in children with ALL as well as in healthy children was revealed. The Pearsons linear correlation coefficients between these parameters were r = -0.364 (p < 0.001) and r = -0.313 (p = 0.019) for the oral cavity and for the pharynx, respectively. The streptococci showing antagonistic activity had only some influence on the count of staphylococci in the oral cavity. The Pearson's linear correlation coefficient between this number and the count of staphylococci in 1 ml of saliva was r = -0.382 (p < 0.001).

[Antagonistic properties of bacterial flora in the mouth and throat of children]. / Antagonistyczne wlasciwosci flory bakteryjnej jamy ustnej i gardla u dzieci.

The research concerned the antagonistic activity of oral and pharyngeal bacterial flora in 44 children, of both sexes, aged 4-15. These properties were estimated basing upon in vitro inhibition of the growth of the standard indicator strains Staphylococcus aureus 209P and Escherichia coli K-12. Bacteria, both aerobic as well as anaerobic, inhibiting the growth of S. aureus 209P were found in every sample. The median percentages of bacteria showing these properties were not significantly different in both environments and they ranged from 25% to 33%. The antagonistic activity of oral and pharyngeal bacterial flora against the indicator strain E. coli K-12 was significantly lower when compared with the activity against the staphylococcal strain.

[Production of glycocalyx by coagulase negative staphylococci isolated from the oral cavity]. / Wytwarzanie glikokaliksu przez gronkowce koagulazo-ujemne izolowane z jamy ustnej.

The study was aimed at determination whether and how frequently coagulase-negative staphylococci persisting in human oral cavity possess the same feature. The material consisted of 255 strains of coagulase-negative staphylococci isolated from oral cavity of persons of both sexes and in differing age. Glycocalyx production by these strains was tested quantitatively by a colorimetric method. Glycocalyx was produced by 222 out of 225 tested strains (87.1%). For individual genera this frequency was following: epidermidis 164/186, hominis 14/14, warneri 12/13, saprophyticus 7/8, auricularis 4/5, haemolyticus 1/4, simulans 4/4, caseolyticus 2/2, xylosus 0/1 and for unidentified 14/18. Majority of tested strains produced only slight amounts of the glycocalyx. Only 46 out of the -20.7% of active strains (18.0% of all tested strains) produced large amount of glycocalyx. Among these strains, 37 belonged to the genus epidermidis, 6 to hominis and one each to warneri, simulans and auricularis. There was no correlation between amount of glycocalyx produced by individual strains and their number in the oral cavity. These results indicate that production of glycocalyx is a common feature of coagulase-negative staphylococci belonging to different genera and may appear with different intensity. Oral cavity may be a source of strains producing large amounts of glycocalyx and thus potentially pathogenic.

[Influence of antagonistic flora on quantity of staphylococci in the oral cavity]. / Wplyw flory antagonistycznej na liczebnosc gronkowców w jamie ustnej.

The study was aimed at establishment, whether in oral cavity co-inhabit bacteria demonstrating antagonistic properties against staphylococci and whether this phenomenon may influence the size of staphylococcal population in this environment. Two locations of bacteria in oral cavity were investigated--saliva and tooth plaque. It was found that total quantity of staphylococci (both coagulase-positive and/or coagulase-negative) in saliva decreases with the age of investigated persons. Mean values amount respectively for children to 3.5 +/- 1.0 log CFU/ml and for adults to 2.9 +/- 0.7 log CFU/ml. This is statistically different (p = 0.0003). Amount of staphylococci in tooth plaques remains generally at the same level and amount to 1.4 +/- 0.6 log CFU/ml. In each tested sample of saliva and tooth plaque, presence of bacteria antagonistic to isolated from a given sample staphylococci, was detected. Among 2-4 year children and in adults, percentages of antagonistic bacteria against coagulase-positive staphylococci were higher than against coagulase-negative strains. Among children aged 5-6 and 11-13 years opposite proportions were found. Statistic analysis confirmed existence of negative correlations, both linear and ranking, between quantity of antagonistic bacteria and amounts of coagulase-positive and coagulase-negative staphylococci in the same tested samples of saliva and tooth plaque. These results suggest that antagonism between bacterial flora of oral cavity and staphylococci, is presenting one of factors limiting the quantity of staphylococci in this environment.

[Antagonism between oral cavity streptococci and staphylococci]. / Antagonizm miedzy paciorkowcami jamy ustnej a gronkowcami.

The subject of this study was investigation of quantitative relations between streptococci, lactic acid bacilli and actinomycetes and staphylococci present in the oral cavity. It was found that in each tested sample of saliva streptococci are present which inhibit growth of an indicator strain Staphylococcus aureus 209P. Percentage of such streptococci varies from 11.1% to 100% (mean value 52.9 +/- 19.7%). There is a negative correlation between number of streptococci and staphylococci in samples of saliva delivered from the same oral cavity. Pearson's linear correlation coefficient was r = -0.7962 (p < 0.0001), and Spearman's correlation rank was rs = -0.7667 (p < 0.0001). Lactic acid bacilli were inhibiting growth of staphylococci only in conditions in which there were not neutralized by organic acids produced by these microorganisms. Actinomycetes had no influence at all on growth of these microorganisms. These results suggest that streptococci are responsible for antagonistic properties of oral cavity bacterial flora in relation to staphylococci. Numbers of streptococci conditions size of staphylococcal population in this environment. Staphylococci practically exert no antagonistic activity against cohabiting with them streptococci.

[Influence of antagonistic bacteria on quantity of staphylococci in the oral cavity]. / Wplyw bakterii antagonistycznych na liczebnosc gronkowców w jamie ustnej.

The study was aimed at establishment whether antagonistic influence between physiological oral cavity bacterial flora and staphylococci do exist and whether they influence on quantity of staphylococci in oral cavity environment. In samples of saliva taken from group of 11-13 year old children and a group of adults of both sexes, determinations were performed regarding total number of bacteria, number and percentage of bacteria inhibiting in vitro growth of standard indicator strain Staphylococcus aureus Oxford 209P and total number and percentage of staphylococci (together coagulase-positive and/or coagulase-negative). It was found that in each saliva sample bacteria inhibiting the indicator strain are present and their mean percentage is significantly higher in children than in adults and amounts respectively 47.1 +/- 28.5 and 35.0 +/- 20.3 (p = 0.0316). Higher percentage of antagonistic bacteria in children is associated with lower percentage of staphylococci in bacterial flora of saliva. Statistical analysis has confirmed existence of negative correlation, both linear and ranking, between the number of antagonistic bacteria and percentage of staphylococci in the saliva. This correlation is more strongly expressed and significant in children than in adults and linear correlation coefficient of Pearson amounts respectively to r = 0.7521 (p < 0.0005) and r = 0.3325 (p < 0.05). These results indicate that antagonistic bacterial flora is a significant factor limiting quantity of staphylococcal population in human oral cavity, especially in children.

[Quantitative changes of bacterial flora from the oral cavity and throat in children with acute lymphoblastic leukemia]. / Zmiany ilosciowe flory bakteryjnej jamy ustnej i gardla u dzieci z ostra bialaczka limfoblastyczna.

Quantitative investigations were carried on aerobic and anaerobic bacterial flora of oral cavity and throat in 44 children in the age of 5-10 years with acute lymphoblastic leukemia, intensively treated with cytostatics, and in 23 healthy children which served as a control group. Samples of saliva from leukemic children revealed significantly higher than in control group--presence of aerobic bacteria, particularly streptococci and enterococci. Material from throat was differing only in regard to staphylococci. Moreover, in children with leukemia, Gram-negative rods were present, which was not the case in the control group.

[Elastolytic activity of staphylococci isolated from human oral cavity]. / Elastolityczna aktywnosc gronkowców jamy ustnej czlowieka.

Elastolytic activity of 292 strains of staphylococci isolated from saliva samples obtained from children and adults was examined. It was found that 41% of coagulase-positive and 57.1% of coagulase-negative staphylococci were able to produce elastase. The difference in production frequency in relation to the ability to produce coagulase was statistically significant (p less than 0.01). Among coagulase-negative strains in addition to S. epidermidis, S. hominis, S. saprophyticus, S. haemolyticus, S. simulans, S. capitis, S. warneri and several unidentified strains were able to produce elastase.