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PubMed2000

Allelic losses demonstrate monoclonality of multifocal bladder tumors.

The clonality of multifocal bladder tumors has been studied over the years with some controversial results. We have examined 5 patients with 2-11 low-grade superficial multifocal bladder tumors for loss of heterozygosity (LOH) at 87 loci on 9 chromosomes. When LOH was detected at a given marker, the tumors consistently showed deletion of a specific allele, suggesting the monoclonality of the patients' tumors. No allelic imbalancies were detected between heterozygote alleles, and the allelic losses were only slightly biased toward the loss of the shorter alleles as the overall ratio was 0.48 +/- 0.10 (0.50 for nonbiased). We calculated the probabilities for monoclonality using binomial distribution. The use of multiple tumors with multiple microsatellite markers gives high statistical power for the calculation. The combined probabilities for monoclonality varied from 0.984 to (1-4 x 10(-28)). Thus, in most (4/5) cases, the probability for polyclonality was <2 x 10(-16). These results demonstrate that superficial multifocal bladder tumors are most likely of monoclonal origin.

Alleles↗
PubMed2000

Maternal thrombocytopenia at term: a population-based study.

BACKGROUND: Thrombocytopenia is a common problem during pregnancy and often inappropriately managed. This study aimed to assess the prevalence and causes of maternal thrombocytopenia at term with special attention to immune mechanisms of thrombocytopenia and the need for assessing fetal risks. METHODS: We conducted a 1-year population-based surveillance study involving 4,382 fullterm (at least 37 weeks' gestation) women (83.8% of the study population) and their infants from the city of Helsinki. Maternal and cord platelet counts were performed at delivery. Immune studies were performed if maternal platelet counts were less than 100 x 10(9)/l; 95% confidence intervals (CIs) were calculated from the binomial distribution. RESULTS: A total of 317 women (7.3%; 95% CI 6.5, 8.1) had platelet counts of less than 150 x 10(9)/l. Most cases (81%) of maternal thrombocytopenia at term were due to gestational thrombocytopenia, which had no impact on either the mother or the fetus unless associated with some other medical or obstetric disorder. Other causes of thrombocytopenia were preeclampsia (16%) and idiopathic thrombocytopenic purpura (ITP) (3%). There was no association between maternal and fetal platelet counts: of the infants born to thrombocytopenic mothers, 2.1%, had thrombocytopenia in the cord blood, which did not differ significantly from the 2.0% of thrombocytopenic infants born to non-thrombocytopenic mothers. CONCLUSION: Women with gestational thrombocytopenia do not require alteration of their treatment. Fetal blood sampling is not considered necessary when thrombocytopenia is discovered unexpectedly at term.

Adult↗
PubMed2000

The contribution of uniparental disomy to congenital development defects in children born to mothers at advanced childbearing age.

Most instances of maternal uniparental disomy (UPD) start as trisomies and, similar to the latter, show a significant increase of mean maternal age at delivery. To investigate the incidence of UPD in offspring of older mothers, we investigated two groups of patients: 1) 50 patients with unclassified developmental defects born to mothers 35 years or older at delivery were tested for UPD for all autosomes by means of microsatellite marker analysis; 2) The incidence of UPD versus other etiologies in correlation, with maternal age below versus 35 years and above at delivery was studied in patients investigated in our laboratory for maternal UPD 15 (Prader-Willi syndrome, PWS), paternal UPD 15 (Angelman syndrome, AS), and maternal UPD 7 (Silver-Russell syndrome, SRS). In group 1, four patients of 50 showed UPD for an autosome that clarified the etiology of their developmental problems: a 27-year-old woman with growth retardation and early puberty disclosed maternal heterodisomy 14; a 15-year-old girl revealed paternal isodisomy 15; a 6-year-old boy with suspected Smith-Lemli-Opitz syndrome was shown to have maternal heterodisomy 16 with additional mosaic partial trisomy 16(pter-p13); a 16-month-old girl with intrauterine growth retardation and a dysmorphic pattern revealed maternal heterodisomy 7. In group 2 the offspring of older mothers showed a clear increase of UPD compared with the mothers below 35 years at delivery. The binomial distribution gave P-values of 1.9 x 10(-10), 2.6 x 10(-4), and 0.01 for PWS, AS, and SRS, respectively. The correlation between increase of paternal UPD 15 with advanced maternal age might be explained by maternal non-disjunction leading to hypohaploid gamete (nullisomy) for chromosome 15 with subsequent or concomitant duplication of the paternal homologue (paternal isodisomy). The three UPD 15 AS cases with mothers older than 35 years at delivery revealed isodisomy, whereas the three cases from younger mothers showed heterodisomy. This study confirms the hypothesis that uniparental disomy is a not negligible cause of congenital developmental anomalies in children of older mothers.

Abnormalities, Multiple↗
PubMed2001

Characterization of the variability of glutamatergic synaptic responses to presynaptic trains in rat hippocampal pyramidal neurons.

Excitatory postsynaptic currents from CA3 hippocampal neurons, elicited by trains of presynaptic action potentials either in mossy fibres or associative commissural fibres, have been analysed, by using a quantal analysis approach, in order to characterize their variability and the correlation among successive responses. As quantal parameters may change during the train according to the previous release events, correlation within consecutive EPSCs is expected. We tested simple hypotheses on how quantal parameters p and N may change on the basis of correlation detection in EPSCs. The statistical significance of these tests has been evaluated. The tests showed that, although simple binomial distributions can give a good description of synaptic responses at the level of single spikes, only stochastic chains can always account for correlations observed within the train. A systematic model fitting procedure has been developed and applied to extract information on the dynamics of synaptic transmission. As an application of this novel type of analysis, a measure of transmitted information to be associated with synaptic variability, a quantity that allows an estimate of the capability of the synapse to transmit reliable information in time, is proposed. We showed that this transmitted information depends on short-term plasticity and that the change in the type of short-term plasticity from facilitating to depressing obtained by increasing the extracellular calcium concentration results in a change of the related transmitted information.

Action Potentials↗
PubMed2001

Estimation of the average burst size of Phix174 am3, cs70 for use in mutation assays with transgenic mice.

In mutation assays using transgenic mice, with recoverable vectors such as PhiX174 am3, cs70, mutations originate from two sources: (1) in vivo mutations, that is, mutations that were fixed in the mouse, or (2) ex vivo mutations, that is, mutations that were fixed during recovery or plating. When a bacteriophage infects a bacterium, it multiplies and bursts the cell, releasing a number of phages referred to as the burst size. Our method for distinguishing between in vivo mutations and ex vivo mutations estimates the average number of bursts, the denominator of in vivo mutant frequencies, by dividing the total plaque-forming units (PFU) by the average number of phages in a burst. Herein, we outline a probability model relating observed plaque counts to the burst size and present the statistical method used to estimate the burst size. The average size of a single burst from nonrevertant phages was estimated in eight studies under the conditions of our mutation assay. The average burst size was stable across studies at 182.5 plaques per burst (standard error, 14.25). The probability that a burst is a specific size was approximated by a negative binomial distribution, which implies a Poisson-Pascal distribution for the observed plaque counts. The observed plaque counts were adequately fit by this approximation. Environ. Mol. Mutagen. 37:356-360, 2001 Published 2001 Wiley-Liss, Inc.

Animals↗
PubMed1975

Enolase isoenzymes. II. Hybridization studies, developmental and phylogenetic aspects.

1. Hybridization studies have been carried out in vitro using mixtures of partially purified isoenzymes 1 and 3 of rat enolase (2-phospho-D-glycerate hydrolyase, EC 4.1.1.11). Immunological methods were used to demonstrate the formation of the hybrid. 2. Immunological analysis of the elution peaks from QAE-Sephadex chromatography of heart enolase indicates the occurrence in vivo of the hybrid enolase 2. 3. Developmental changes in the proportions of isoenzymes 1, 2 and 3 in heart and skeletal muscle of rat have been studied quantitatively. In both tissues isoenzyme 1 predominates in the foetus, but is partially replaced by 2 and 3 in adult heart and completely by 3 in the adult muscle. 4. Evidence is given of the binomial distribution of the proportions of the three isoenzymes in the developing heart. 5. Phylogenetic studies of the immunological properties of enolases from muscle, liver and heart have been carried out. 6. It is concluded that the three isoenzymes arise from two independent genetic loci and it is suggested that these evolved from a common ancestral gene 200-300 million years ago.

Aging↗
PubMed1975

Proportions with extraneous variance: two dependent samples.

Data which appear to be binomial proportions sometimes exhibit heterogeneity which results in greater variation than would be exhibited under the binomial distribution. Previous work by the author (Kleinman [1973]) in which estimates of the heterogeneity variances are obtained and used in weighting is extended to the case of comparing means in two dependent samples. The resulting empirical weighting estimates are asymptotically equivalent to exact least squares estimates and Monte Carlo studies for sample size 10 indicate high efficiency relative to exact least squares estimates.

Analysis of Variance↗
PubMedDate not supplied

Sampling grain shipments to detect genetically modified seed.

Using the binomial distribution, the effect of sample size on the variability among sample test results when sampling a lot with 1.0% genetically modified (GM) or biotech seed was evaluated. The coefficient of variation, cv, among 500-seed sample test results taken from a lot with truly 1.0% was computed to be 44.5%. Increasing sample size to 1000 seeds reduced the cv among sample test results to 31.5%. The effects of sample size and accept/reject limits on the buyer's risk (bad lots accepted) and the seller's risk (good lots rejected) was also evaluated assuming a tolerance of 1.0% GM seed. Increasing sample size decreases both the buyer's and seller's risks at the same time. Using an accept/reject limit below the regulatory tolerance decreases the buyer's risk, but increases the seller's risk. Using an accept/reject limit above the regulatory tolerance decreases the seller's risk but increases the buyer's risk.

Analysis of Variance↗
PubMedDate not supplied

[The parasite capacity of the host population].

The estimation of parasitic pressure on the host populations is frequently required in parasitological investigations. The empirical values of prevalence of infection are used for this, however the latter one as an estimation of parasitic pressure on the host population is insufficient. For example, the same prevalence of infection can be insignificant for the population with high reproductive potential and excessive for the population with the low reproductive potential. Therefore the development of methods of an estimation of the parasitic pressure on the population, which take into account the features the host population, is necessary. Appropriate parameters are to be independent on view of the researcher, have a clear biological sense and be based on easily available characteristics. The methods of estimation of parasitic pressure on the host at the organism level are based on various individual viability parameters: longevity, resistance to difficult environment etc. The natural development of this approach for population level is the analysis of viability parameters of groups, namely, the changing of extinction probability of host population under the influence of parasites. Obviously, some critical values of prevalence of infection should exist; above theme the host population dies out. Therefore the heaviest prevalence of infection, at which the probability of host population size decreases during the some period is less than probability of that increases or preserves, can serve as an indicator of permissible parasitic pressure on the host population. For its designation the term "parasite capacity of the host population" is proposed. The real parasitic pressure on the host population should be estimated on the comparison with its parasite capacity. Parasite capacity of the host population is the heaviest possible prevalence of infection, at which, with the generation number T approaching infinity, there exists at least one initial population size ni(0) for which the probability of size decrease through T generations is less than the probability of its increase. [formula: see text] The estimation of the probabilities of host population size changes is necessary for the parasite capacity determination. The classical methods for the estimation of extinction probability of population are unsuitable in this case, as these methods require the knowledge of population growth rates and their variances for all possible population sizes. Thus, the development methods of estimate of extinction probability of population, based on the using of available parameters (sex ratio, fecundity, mortality, prevalence of infection PI) is necessary. The population size change can be considered as the Markov process. The probabilities of all changes of population size for a generation in this case are described by a matrix of transition probabilities of Markov process (pi) with dimensions Nmax x Nmax (maximum population size). The probabilities of all possible size changes for T generations can be calculated as pi T. Analyzing the behaviour matrix of transition at various prevalence of infection, it is possible to determine the parasite capacity of the host population. In constructing of the matrix of transition probabilities, should to be taken into account the features the host population and the influence of parasites on its reproductive potential. The set of the possible population size at a generation corresponds to each initial population size. The transition probabilities for the possible population sizes at a generation can be approximated to the binomial distribution. The possible population sizes at a generation nj(t + 1) can be calculated as sums of the number of survived parents N1 and posterities N2; their probabilities--as P(N1) x P(N2). The probabilities of equal sums N1 + N2 and nj(t + 1) > or = Nmax are added. The number of survived parents N1 may range from 0 to (1-PI) x ni(t). The survival probabilities can be estimated for each N1 as [formula: see text] The number of survived posterities N2 may range from 0 to N2max (the maximum number of posterities). N2max is [formula: see text] and the survival probabilities for each N2, is defined as [formula: see text] where [formula: see text], ni(t) is the initial population size (including of males and infected specimens of host), PI is the prevalence of infection, Q1 is the survival probabilities of parents, Pfemales is the frequency of females in the host population, K is the number of posterities per a female, and Q2 is the survival probabilities of posterities. When constructing matrix of transition probabilities of Markov process (pi), the procedure outlined above should be repeated for all possible initial population size. Matrix of transition probabilities for T generations is defined as pi T. This matrix (pi T) embodies all possible transition probabilities from the initial population sizes to the final population sizes and contains a wealth of information by itself. From the practical point of view, however, the plots of the probability of population size decrease are more suitable for analysis. They can be received by summing the probabilities within of lines of matrix from 0 to ni--1 (ni--the population size, which corresponds to the line of the matrix). Offered parameter has the number of advantages. Firstly, it is independent on a view of researcher. Secondly, it has a clear biological sense--this is a limit of prevalence, which is safe for host population. Thirdly, only available parameters are used in the calculation of parasite capacity: population size, sex ratio, fecundity, mortality. Lastly, with the availability of modern computers calculations do not make large labour. Drawbacks of this parameter: 1. The assumption that prevalence of infection, mortality, fecundity and sex ratio are constant in time (the situations are possible when the variability of this parameters can not be neglected); 2. The term "maximum population size" has no clear biological sense; 3. Objective restrictions exist for applications of this mathematical approach for populations with size, which exceeds 1000 specimens (huge quantity of computing operations--order Nmax 3*(T-1), work with very low probabilities). The further evolution of the proposed approach will allow to transfer from the probabilities of size changes of individual populations to be probabilities of size changes of population systems under the influence of parasites. This approach can be used at the epidemiology and in the conservation biology.

Animals↗
PubMed2002

Excessive daytime sleepiness in Campo Grande general population, Brazil.

The prevalence of excessive daytime sleepiness (EDS) in general population was determined by means of 408 home interviews of adults, in a representative sample of Campo Grande city, Brazil. The random sample was stratified by sex, age and economic social status. EDS was considered in those with indexes 11 or more in the Epworth Sleepiness Scale. Statistics used chi-square, Fisher and Pearson tests; and inferences based on binomial distribution parameters; the significance level was 5% and confidence interval (CI) was 95%. The prevalence of EDS was 18.9% of the general population ( SD=1.9%; CI 15.1% to 22.7%). No significant association was found between EDS and the use of hypnotics, nor with insomnia, body mass index, sex, age, years of schooling, economic social status, marital status, occupation and the use of alternative means to improve sleep. When the sample was separated according to sex, only the male group showed significant association between EDS and actual insomnia (p=0.005).

Adolescent↗
PubMed2002

Insomnia and hypnotic use in Campo Grande general population, Brazil.

The insomnia prevalence in general population was determined by means of 408 home interviews of adults, in a representative sample of Campo Grande city, Brazil. The random sample was stratified by sex, age and economic social status. Insomnia subtypes evaluated were the disorders of sleep initiation (DSI), sleep maintenance (DSM) and early awakening (DEA). A structured questionnaire was used with the consent from the interviewed subjects. Statistics used chi-square, and Fisher tests; and inferences based on binomial distribution parameters; the significance level was 5% and confidence interval (CI) was 95%. The general prevalence of insomnia was 19.1% (sd=2.0%), mostly women (p=0.0015), and people of less years of schooling (p=0.0317), subtype DSI (14.2%, p=0.0043), and chronic (p=0.7022). Hypnotic drugs were used by 6.9%(sd=1.3%) in the last month. Use in the last 2 years, 70.3% mostly insomniacs (p<0.0001), women (p=0.0372) and people over 30 years of age (p=0.0536).

Adult↗
PubMed2003

Behavioral contagion in an experimental motion environment.

BACKGROUND: It is generally understood that whole-body movement up and down can produce motion sickness. A standard reference, published in this journal in 1974, found that a frequency of 6 cycles per minute was most productive of motion sickness. The 1974 study used a vertical oscillator carrying two subjects at a time. The investigators were, of course, aware that the sight, sound, or smell of another person being ill might itself contribute to sickness. Accordingly, the two subjects were located in completely separate compartments, each soundproofed and with its own independent air-conditioning system. The sessions were scheduled to last 2 h. However, if a subject "pre-terminated" (became ill or requested removal), the oscillator was stopped while the subject debarked. METHODS: The present study is a secondary analysis of data elements not reported in the original study, namely, the frequency of pairs in which 0, 1, or 2 subjects pre-terminated. If knowing that the other subject had pre-terminated had no effect on whether the remaining subject pre-terminated, then the pairs in which 0, 1, or 2 subjects pre-terminated should be distributed binomially. RESULTS: Independent pre-termination of the two subjects in a pair was rejected (p < 0.001). The likelihood that a subject would pre-terminate increased strongly when the subject's partner pre-terminated. This effect was twice as large when the motions of the oscillator were severe as when they were less severe. CONCLUSIONS: Pre-termination by one subject legitimized pre-termination by example, and thereby increased the risk that the remaining subject would also pre-terminate (behavioral contagion).

Humans↗
PubMed1978

Bioassay of cupferron for possible carcinogenicity (CAS No. 135-20-6).

A bioassay of cupferron for possible carcinogenicity was conducted using Fischer 344 rats and B6C3F1 mice. Cupferron was administered in the feed, at either of two concentrations, to groups of 49 or 50 male and 50 female animals of each species. The time-weighted average high and low dietary concentrations of cupferron were, respectively, 0.30 and 0.15 percent for male and female rats, and 0.4 and 0.2 percent for male and female mice. After a 78-week period of compound administration, observation of the rats continued for an additional period of up to 28 weeks and observation of the mice continued for an additional period of up to 18 weeks. For each species, 50 animals of each sex were placed on test as controls and fed only the basal diet. Among both sexes of rats and mice there was a significant positive association between the dose of cupferron administered and mortality; however, in all groups of animals sufficient numbers survived long enough to establish the carcinogenicity of this compound. There were significant positive associations between the concentrations of cupferron administered to male and female rats and the incidences of: squamous-cell carcinomas of the forestomach, hepatocellular carcinomas and neoplastic nodules, and hemangiosarcomas. When a binomial distribution and a spontaneous incidence rate corresponding to the appropriate historical control incidence were assumed, the incidences of auditory sebaceous gland neoplasms in female rats and female mice were significant. There were significant positive associations between the concentrations administered and the incidences of hepatocellular carcinomas in female mice, the incidences of hemangiosarcomas in both sexes of mice, and the incidence of Harderian gland adenomas in both sexes of mice. Under the conditions of this bioassay cupferron was carcinogenic in Fischer 344 rats, causing hemangiosarcomas, hepatocellular carcinomas, and squamous-cell carcinomas of the forestomach in males and females as well as carcinomas of the auditory sebaceous gland in females. The chemical was also carcinogenic in B6C3F1 mice, causing hemangiosarcomas in males and hepatocellular carcinomas, carcinomas of the auditory sebaceous gland, a combination of hemangiosarcomas and hemangiomas, and adenomas of the Harderian gland in females.

Journal Article↗
PubMed1978

Bioassay of phenazopyridine hydrochloride for possible carcinogenicity.

A bioassay of phenazopyridine hydrochloride for possible carcinogenicity was conducted by administering the test chemical in feed to Fischer 344 rats and B6C3F1 mice. Groups of 35 rats and 35 mice of each sex were administered phenazopyridine hydrochloride at one of the following doses, either 3,700 or 7,500 ppm for rats and either 600 or 1,200 ppm for mice. The rats were administered the chemical for 78 weeks, then observed for 26 or 27 additional weeks; the mice were administered the chemical for 80 weeks, then observed for 25-27 additional weeks. Matched controls consisted of 15 untreated rats and 15 untreated mice of each sex. All surviving rats were killed at 104 or 105 weeks, all surviving mice at 105-107 weeks. Mean body weights of the dosed rats and mice of each sex were consistently lower than those of corresponding control animals, and the depressions in mean body weight were dose related. Mortality in the groups of rats and mice did not, however, show dose-related trends, and sufficient numbers of animals of both dosed and control groups were at risk for the development of late-appearing tumors. In male rats, adenomas or adenocarcinomas of the large intestine (colon or rectum) occurred at incidences having a significant dose-related trend (P=0.015). The direct comparison of the incidences in each of the dosed groups with that in the control group was not significant (controls 0/14, low-dose 4/34, high-dose 8/35). In the females, 3/33 low-dose and 5/32 high-dose animals, but no control animals, had this tumor. In addition, sarcomas were observed in the colon of one low-dose male and one high-dose female. The laboratory historical records showed no incidence of adenomas or adenocarcinomas of the large intestine in 260 females and only one adenomatous polyp in 260 males. Assuming a spontaneous incidence of 1/261 (0.038%) and a binomial distribution of such tumors, the occurrence seen in the male and female high-dose groups are both significantly (P<0.001) different from the expected value. Thus, these tumors are considered to be related to administration of the test chemical. In female mice, the combined incidence of hepatocellular adenomas and carcinomas showed a significant dose-related trend (P=0.002), and the incidence in the high-dose group was significant (P=0.003) when compared with that in the control group (controls 2/15, low-dose 11/34, high-dose 19/32). The incidence of hepatocellular carcinomas, considered alone, also was significant in female mice, showing a dose-related trend (P=0.010) and a P value of 0.039 for the comparison of the high-dose group with the control group. In the males, the combined incidence of hepatocellular adenomas and carcinomas was not significant. It is concluded that under the conditions of this bioassay, phenazopyridine hydrochloride was carcinogenic in Fischer 344 rats, inducing adenocarcinomas of the colon in both males and females. Although phenazopyridine hydrochloride was not carcinogenic in male B6C3F1 mice, the chemical was carcinogenic in females, inducing hepatocellular adenomas and carcinomas.

Journal Article↗
PubMedDate not supplied

[The long-term follow-up of 1000 patients with a valve replacement by the prosthesis of the Instituto Nacional de Cardiología Ignacio Chávez].

The long-term follow-up of patients with bioprosthetic valves manufactured at the Instituto Nacional de Cardiología Ignacio Chávez is presented. From February 1983 to May 1990, 1068 patients were operated and 1252 valves were replaced. Eighty two percent had rheumatic heart disease with one or more injured valves. In 17% it was a replacement of a failing valve. Seventy three percent of the patients had a low or medium-low socioeconomical status. There were 176 perioperative deaths in the first month after the operation and 150 patients were lost to follow-up. The rest (740) are the subject of this report. Mortality associated with valve related complications had a probability of 0.74 +/- 0.05, it had a significative increase after month 70th, with a 88% survival at that time. The functional class in the whole group improved 90%, with confidence limits for binomial distribution between 85 and 97%. There was also a significant reduction in heart enlargement. There were 161 prosthesis dysfunctions due to valve calcification or rupture, 50 were replaced. Twenty-three patients had hemolysis, and 19 infective endocarditis. There were 6.5% with systemic embolism in spite that only one half of those in which there was an indication, different of the valve replacement, received anticoagulant medication. The use of this prosthesis is on economical and medical satisfactory solution for the problem of a great number of our population of patients.

Academies and Institutes↗
PubMed2003

[Discovery of analogous balanced translocation syndrome and its clinical genetics research].

OBJECTIVE: To find out the clinical genetic law of relation between a group of special chromosomal structural abnormality including bit Y, inv(9), S+, No. 1, 9, 16 chromosomal qh+/-, and the balanced translocation. METHODS: By means of binomial distribution method, 980 cases were analyzed for balanced chromosome translocation, big Y, inv(9), S+ and qh+/-, and according to the clinical features the 980 cases were divided into 4 groups: spontaneous abortion, abnormal sexual development, labouring disease and disabled or diseased condition of the patient. RESULTS: In these 980 cases of balanced translocation, big Y, inv(9), S+ and qh+/-, the chief clinical features caused by the various different conditions have a high similarity (P > 0.20-0.50). CONCLUSION: The big Y, inv(9), S+, and qh+/- leading to the occurrence of the chief clinical features belong to the analogous balanced translocation syndrome. This fact indicates that in the process of sexual reproduction, the minute unequivalent exchange in the molecular level of gamete is possible to have genetic effect in the descendants, and may cause a corresponding clinical feature, present the abnormal sex differentiation, in varying degrees, and influence the abnormal phenotype or the health of individuals.

Abortion, Habitual↗
PubMedDate not supplied

[The characteristics of the ixodid tick-vertebrate animal parasitic system].

The parasitic system ixodid tick (parasite)--vertebrate animal (host) is relatively stable in space and time. Equilibrium state in the system is maintained at the low levels of the hosts' infection and moderate intensity of their immunity. Parasite sensitizes the host's organism at the stage of feeding on antigens of its saliva and the host develops different degrees of resistance preventing the subsequent individuals of ticks from normal feeding. Antitick immunity is species specific. Its intensity is defined by the species belonging of the parasite and host, intensity and intervals between infections, availability of "anti-immune mechanisms" in tick and by many other factors, which are realized at the feeding stage. Regulation of the number of ticks, depending on their abundance in the host's population, is attained due to the oversparse, close to negative binomial distribution on hosts. This mechanism functions on the principle of feedback, so that at the excessive number of the parasite some individuals in the host's population, which are especially subjected to infection, do not cope with parasitic burden and die. However, ticks, which failed to finish their feeding and represent a disproportionately great part of the whole parasite's population, die together with them and the parasitic system quickly restores its stability. In anthropocoenoses and ecosystems at different stages of anthropogenic transformation mutual regulation mechanisms of the parasite and host number break down. As a consequence, extremely high rises in the number of ticks and epizootics of agricultural animals associated with them can occur.

Animals↗
PubMed2003

Nodular fasciitis: clinical characteristics and preoperative diagnosis.

BACKGROUND AND PURPOSE: Because of its rapid growth, hypercellularity, and brisk mitotic rate, nodular fasciitis (NF) is probably the most common benign mesenchymal tumor that is misdiagnosed as a sarcoma, often leading to unnecessary and overly aggressive therapy. METHODS: This retrospective study evaluated the characteristics of 92 well-documented cases of NF treated from 1988 to 2001. Gender, age, location, size, and clinical symptoms were analyzed, as was the accuracy of preoperative diagnosis. RESULTS: Females were predominant (male-to-female ratio, 1:1.71; p = 0.006, binomial distribution). Accurate preoperative diagnosis was made in only 14.1%, but this rate improved in recent years (p = 0.034, chi-squared test for trend). The pathologic subtype of NF did not correlate with the duration of the lesion. CONCLUSIONS: Clinicians should include NF in the differential diagnosis of rapidly growing subcutaneous tumors and not rush to overly aggressive therapy.

Adolescent↗