Biology subjects

Flegr, J.

Publications and source records attributed to Flegr, J..

12 recordsLinked to original sources

bioRxiv2018

Perinatal outcomes, maternal age, parity and fetal sex - searching for the \"optimal\" maternal age

BackgroundMaternal age, parity and fetal sex are each known to affect obstetric and birth outcomes. The objective of the present study was to investigate the influence of the combination of maternal age, parity and fetal sex on outcomes of pregnancies._The aim of the study was to analyze the influence of maternal age on perinatal outcomes in both primiparous and multiparous women with different fetal sex.\n\nMethodsThe cross-sectional study was performed on data from 11,780 women, who have given birth at the General University Hospital in Prague, Czech Republic between 2008-2012.\n\nResultsMaternal age significantly (P<0.01) influenced pregnancy weight gain, duration of pregnancy, birth weight and birth length. Primiparous women with female newborns aged [≤]19 had higher rates of preterm delivery than comparable women 20-39 (P=0.012). Similarly, women with male newborns aged [≥]40 had higher rates of preterm delivery than comparable women 20-39 (P=0.003). Women aged [≤]24 expressed higher rates of low birth weight than women aged >24 (P<0.001), regardless of parity and fetal sex. The older ([≥]35) primiparous women with male newborns expressed a higher incidence of macrosomia (P=0.021) compared to other groups of women. The probability of caesarean delivery increased with age (P<0.001) and it was significantly affected by the parity and sex of the newborn with higher rates of caesarean section in primiparous women as well as in mothers carrying male fetuses.\n\nConclusionsOur results indicate that \"optimal\" maternal age without obstetrics and birth complications is 25-34 years, older age is associated with increased complications with a male fetus, especially in primiparous women. Our data suggests that not just the age of women, but the combination of age, parity, and fetal sex should be taken into consideration during assessment of health risks of pregnancy.

epidemiology↗

bioRxiv2018

Differences in cognitive functions between cytomegalovirus-infected and cytomegalovirus-free university students: a case-control study

Cytomegalovirus (CMV) is the herpetic virus, which infects 45-100% people worldwide. Many reports suggest that CMV could impair cognitive functions of infected subjects. Here we searched for indices of effects of CMV on infected subjects' intelligence and knowledge. The Intelligence Structure Test I S T 2000 R was used to compare IQ of 148 CMV infected and 135 CMV free university students. Infected students expressed higher intelligence. Paradoxically, their IQ decreased with decreasing concentration of anti CMV antibodies, which can be used, statistically, as a proxy of the time passed from the moment of infection in young subjects when the age of subjects is statistically controlled. The paradox of seemingly higher intelligence of CMV infected subjects could be explained by the presence of the subpopulation of about 5-10 % CMV positive individuals in the population of "CMV negative students". These false negative subjects had probably not only the oldest infections and therefore the lowest concentration of anamnestic antibodies, but also the lowest intelligence among the infected students. Prevalence of CMV infection in all countries is very high, approaching sometimes 90 %. Therefore, the total impact of CMV on human intelligence may be large.

neuroscience↗

bioRxiv2018

Depressiveness and Neuroticism in Bartonella Seropositive and Seronegative Subjects - Preregistered Case-Controls Study

Several recent studies have demonstrated the association of cat-related injuries with major depression and with depressiveness in the general population. It was suggested that cat-scratch disease, the infection with the bacterium Bartonella henselae, can be responsible for the observed association. However, no direct evidence for the role of the Bartonella infection in this association has been published until now. In this preregistered case-controls study performed on 250 healthy subjects tested earlier for the presence of anti-Toxoplasma IgG antibodies, we searched for the positive association between presence of anamnestic anti-Bartonella IgG antibodies and depressiveness measured with Beck II inventory, depression subscale of neuroticism measured with N-70 questionnaire, and self-reported health problems. We found that that Bartonella-seropositivity was positively correlated with Beck depression only in Toxoplasma-seronegative men and negatively correlated with health in Toxoplasma-seronegative women. Bartonella seropositivity expressed protective effects against Toxoplasma seropositivity-associated increased neuroticism in men while Toxoplasma-seropositivity expressed protective effects against Bartonella seropositivity-associated health problems in women. A comparison of the patterns of association of mental and physical health problems with Bartonella seropositivity and with reported cat-related injury suggests that different factor, possibly infection with different pathogen transmitted by cat related-injuries than the Bartonella henselae, is responsible for the observed association of cat related-injuries with depressiveness and major depression. The existence of complex interactions between Bartonella seropositivity, Toxoplasma seropositivity, and sex also suggest that the effect of symbionts on the host's phenotype must by always studied in the context of other infections, and separately for men and women.

neuroscience↗

bioRxiv2018

Lower performance of Toxoplasma-infected, Rh-negative subjects in the weight holding and hand-grip tests

Toxoplasma, a protozoan parasite of cats, infects many species of intermediate and paratenic hosts, including about one-third of humans worldwide. After a short phase of acute infection, the tissue cysts containing slowly dividing bradyzoites are formed in various organs and toxoplasmosis proceeds spontaneously in its latent form. In immunocompetent subjects, latent toxoplasmosis was considered asymptomatic. However, dozens of studies performed on animals and humans in the past twenty years have shown that it is accompanied by a broad spectrum of specific behavioural, physiological and even morphological changes. In human hosts, the changes often go in the opposite direction in men and women, and are mostly weaker or non-existent in Rh-positive subjects. Here, we searched for the indices of lower endurance of the infected subjects by examining the performance of nearly five hundred university students tested for toxoplasmosis and Rh phenotype in two tests, a weight holding test and a grip test. The results confirmed the existence of a negative association of latent toxoplasmosis with the performance of students, especially Rh-negative men, in these tests. Surprisingly, but in an accordance with some already published data, Toxoplasma-infected, Rh-positive subjects expressed a higher, rather than lower, performance in our endurance tests. Therefore, the results only partly support the hypothesis for the lower endurance of Toxoplasma infected subjects as the performance of Rh-positive subjects (representing majority of population) correlated positively with the Toxoplasma infection.

pathology↗

bioRxiv2017

Toxoplasmosis, but not borreliosis, is associated with psychiatric disorders: A cross-sectional survey on 46 thousand of subjects

Infection by the parasite Toxoplasma, which affects about 33% of world population, is associated with increased risk of several mental health disorders, the most strongly with schizophrenia. It is unknown whether toxoplasmosis really plays a substantial role in the etiopathogenesis of these disorders and whether schizophrenia is associated with this infection the most strongly, or whether this association has just been the most intensively studied for historical reasons. We used the data from 3,440 and 7,800 subjects tested for toxoplasmosis and borreliosis, respectively, who took part in an internet survey, for searching in the associations of these infections with 22 mental health disorders and other indices of impaired mental health. The typical symptom associated with toxoplasmosis was anxiety, and the typical toxoplasmosis-associated disorders were autism (OR=4.86), schizophrenia (OR=3.34), attention deficit hyperactivity disorder (OR=3.02), Asperger syndrome (OR=2.49), antisocial personality disorder (OR=1.81), OCD (OR=1.69), and anxiety disorder (OR=1.57). Borreliosis was associated only with symptoms of depression and with major depression (OR=1.65). The negative effects of borreliosis were detectable only in the Toxoplasma-infected subjects. Toxoplasmosis could play a substantial role in the etiopathogenesis of mental health disorders and its association with schizophrenia is the second strongest association, after autism.

neuroscience↗

bioRxiv2017

Effects of latent toxoplasmosis on olfactory functions of men and women

The prevalence of toxoplasmosis is higher in schizophrenics than in the general population. It has been suggested that certain symptoms of schizophrenia, including changes in olfactory functions, are in fact symptoms of toxoplasmosis that can be easily detected in schizophrenics only due to the increased prevalence of toxoplasmosis in this population. Schizophrenics have impaired identification of odors and lower sensitivity of odor detection. Here we searched for differences in olfactory functions between 62 infected and 61 noninfected non-schizophrenic subjects. The infected men scored better in the standard odor-identification test. The infected women rated all smells as more intensive while the infected men rated nearly all smells as less intensive. Infected women rated the pleasantness of the smell of undiluted cat urine as higher than the non-infected women and the opposite was true for the men (the opposite direction shifts in men and women were described earlier for highly diluted cat urine). Toxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli. Our results suggest that latent toxoplasmosis is associated with changes in the olfactory functions in humans; however, the observed changes differ from those observed in schizophrenics.\n\nKey findingsO_LIInfected men but not women show better odor identification ability than the non-infected controls.\nC_LIO_LIThe infected women rated all smells as more and men as less intensive than the controls.\nC_LIO_LIThe infected women rated smell of cat urine as more and men as less pleasurable than the controls.\nC_LIO_LIToxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli.\nC_LIO_LIWe found no new evidence for the toxoplasmosis hypothesis of schizophrenia.\nC_LI

animal behavior and cognition↗

bioRxiv2017

Stability-based sorting: The forgotten process behind (not only) biological evolution

Natural selection is considered to be the main process that drives biological evolution. It requires selected entities to originate dependent upon one another by the means of reproduction or copying, and for the progeny to inherit the qualities of their ancestors. However, natural selection is a manifestation of a more general persistence principle, whose temporal consequences we propose to name \"stability-based sorting\" (SBS). Sorting based on static stability, i.e., SBS in its strict sense and usual conception, favours characters that increase the persistence of their holders and act on all material and immaterial entities. Sorted entities could originate independently from each other, are not required to propagate and need not exhibit heredity. Natural selection is a specific form of SBS--sorting based on dynamic stability. It requires some form of heredity and is based on competition for the largest difference between the speed of generating its own copies and their expiration. SBS in its strict sense and selection thus have markedly different evolutionary consequences that are stressed in this paper. In contrast to selection, which is opportunistic, SBS is able to accumulate even momentarily detrimental characters that are advantageous for the long-term persistence of sorted entities. However, it lacks the amplification effect based on the preferential propagation of holders of advantageous characters. Thus, it works slower than selection and normally is unable to create complex adaptations. From a long-term perspective, SBS is a decisive force in evolution--especially macroevolution. SBS offers a new explanation for numerous evolutionary phenomena, including broad distribution and persistence of sexuality, altruistic behaviour, horizontal gene transfer, patterns of evolutionary stasis, planetary homeostasis, increasing ecosystem resistance to disturbances, and the universal decline of disparity in the evolution of metazoan lineages. SBS acts on all levels in all biotic and abiotic systems. It could be the only truly universal evolutionary process, and an explanatory framework based on SBS could provide new insight into the evolution of complex abiotic and biotic systems.

evolutionary biology↗

bioRxiv2017

The mismeasure of (obese) man - body mass index is an inadequate indicator of body condition

The body mass index (BMI), recommended also by the World Health Organization, is currently used as the leading body condition indicator in clinical and epidemiological studies and has become popular among the general public. Here we provide evidence of a systematic bias in BMI, showing that BMI is dependent on body height. As a result, shorter persons have a greater chance of being classified as underweight, while taller persons as overweight, even if they have identical nutritional status. Use of BMI should be thus abandoned in diagnosis as well as in clinical and experimental studies.

physiology↗

bioRxiv2017

General Environmental Heterogeneity As The Explanation Of Sexuality? Comparative Study Shows That Ancient Asexual Taxa Are Associated With Both Biotically And Abiotically Homogeneous Environments

Ecological theories of sexual reproduction assume that sexuality is advantageous in certain conditions, for example, in biotically or abiotically more heterogeneous environments. Such theories thus could be tested by comparative studies. However, the published results of these studies are rather unconvincing. Here we present the results of a new comparative study based solely on the ancient asexual clades. The association with biotically or abiotically homogeneous environments in these asexual clades was compared with the same association in their sister, or closely related, sexual clades. Using the conservative definition of ancient asexuals (i.e. age > 1 million years), we found six pairs for which relevant ecological data are available. The difference between the homogeneity type of environment associated with the sexual and asexual species was then compared in an exact binomial test. Based on available literature, the results showed that the vast majority of ancient asexual clades tend to be associated with biotically or abiotically, biotically, and abiotically more homogeneous environments than their sexual controls. In the exploratory part of the study, we found that the ancient asexuals often have durable resting stages, enabling life in subjectively homogeneous environments, live in the absence of intense biotic interactions, and are very often sedentary, inhabiting benthos and soil. The consequences of these findings for the ecological theories of sexual reproduction are discussed.

evolutionary biology↗

bioRxiv2017

Physical And Mental Health Status In Toxoplasma-Infected Women Before And Three Years After They Learn About Their Infection: The Role Of Rh Factor

Latent toxoplasmosis is known to be associated with specific changes in animal and human behavior and human personality. Many toxoplasmosis-associated shifts, such as an extroversion-introversion shift or a trust -suspicion shift, go in opposite directions in men and women. The stress coping hypothesis suggests that such behavioral effects of toxoplasmosis are side effects of chronic stress caused by lifelong parasitosis and associated health disorders. Several studies have searched for, and typically found, indices of impaired health in infected subjects. However, subjects were always aware of their toxoplasmosis status, which could influence obtained data and cause false-positive results of the studies. Here we searched for differences in physical and mental health status among 39 Toxoplasma-infected and 40 Toxoplasma-free female university students who completed identical questionnaires (N-70, and anamnestic questionnaire), before and 3 years after they were informed of their toxoplasmosis status. Our results showed that infected women showed indices of poorer health status, not only after, but also before they were informed of their infection. In accordance with previously published data, these indices were more numerous and stronger in Rh-negative than in Rh-positive women. Present results suggest that observed indices of poorer health and symptoms of chronic stress in Toxoplasma-infected subjects are real. Due to its high (30%) prevalence, toxoplasmosis could represent an important factor for public health.

neuroscience↗

bioRxiv2017

On The Advantages Of Evolutionary Passivity In Fluctuating Environments: Could Sex Be The Preadaptation For The Stability-Based Sorting?

The ability of organisms to adaptively respond to environmental changes (evolvability) is usually considered to be an important advantage in interspecific competition. It has been suggested, however, that evolvability could be a double-edged sword that could present a serious handicap in fluctuating environments. The authors of this counterintuitive idea have published only verbal models to support their claims.\n\nHere we present the results of individual-based stochastic modelling of competition between two asexual species differing only by their evolvability. They show that, in changeable environments, less evolvable species could outperform their more evolvable competitors in a broad area of a parameter space, regardless of whether the conditions fluctuated periodically or aperiodically. Highly evolvable species prospered better nearly all the time; however, they sustained a higher probability of extinction during rare events of the rapid transient change of conditions.\n\nOur results offer an explanation of why sexually reproducing species, with their reduced capacity to respond adaptively to local or temporal environmental changes, prevail in most eukaryotic taxa in nearly all biotopes on the surface of Earth. These species may suffer several important disadvantages in direct competitive battles with asexual species; however, they might win in changeable environments in the more important sorting-according-to-stability war.

evolutionary biology↗

bioRxiv2017

Health Status By Gender, Hair Color, And Eye Color: Red-Haired Women Are The Most Divergent

BackgroundRed hair is associated with pain sensitivity, and more so in women than in men. Hair redness may thus interact with a female-specific factor. We tested this hypothesis on a large sample of Czech and Slovak respondents. They were asked about the natural redness and darkness of their hair, their natural eye color, their physical and mental health (24 categories), and other personal attributes (height, weight, number of children, lifelong number of sexual partners, frequency of smoking).\n\nResultsWe found that red-haired women did worse than other women in ten health categories and better in only three. In particular, they were more prone to colorectal, cervical, uterine, and ovarian cancer. Cancer risk increased steadily with increasing hair redness except for the reddest shade. Red-haired men showed a balanced pattern of health effects, doing better than other men in three categories and worse in three. Number of children was the only category where both male and female redheads did better than other respondents. We also confirmed earlier findings that red hair is naturally more frequent in women than in men.\n\nConclusionRed-haired women had higher fecundity and sexual attractiveness, but this selective advantage seems offset by worse health outcomes and therefore lower viability. The resulting equilibrium between these two counterbalancing forces might explain why red hair has remained less common than other hair and eye colors. Of the new hair and eye colors, red hair diverges the most from the ancestral state of black hair and brown eyes. It is the most sexually dimorphic variant, not only in population frequency but also in health outcomes. This sexual dimorphism seems to have resulted from a selection pressure that acted primarily on early European women and which led to a general and apparently rapid diversification of hair and eye colors.

evolutionary biology↗