Cytochrome P450 in parasitic protozoa and helminths

Cytochrome P450 has been demonstrated in flagellate and sporozoan Protozoa. In Plasmodium there is a correlation between chloroquine resistance and cytochrome P450 mono-oxygenase activity, but there is no evidence that the malarial parasite metabolises chloroquine by an oxidative mechanism. There is no evidence for cytochrome P450 in adult helminths (nematodes and platyhelminths) based on P450 content and mono-oxygenase activity with classical substrates, although low activities may be present in free-living larval stages.     

Association of malaria parasite population structure, HLA, and immunological antagonism

Host-parasite coevolution has been likened to a molecular arms race, with particular parasite genes evolving to evade specific host defenses. Study of the variants of an antigenic epitope of Plasmodium falciparum that induces a cytotoxic T cell response supports this view. In African children with malaria, the variants present are influenced by the presence of a human leukocyte antigen (HLA) type that restricts the immune response to this epitope. The distribution of parasite variants may be further influenced by the ability of cohabiting parasite strains to facilitate each other's survival by down-regulating cellular immune responses, using altered peptide ligand antagonism.     

The population genetic structure of the facultatively sexual parasitic nematode Strongyloides ratti in wild rats

We have investigated the population genetic structure of the parasitic nematode Strongyloides ratti in wild rats. In the UK, S. ratti reproduces predominantly by mitotic parthenogenesis, with sexual forms present at a rate of less than 1%. S. ratti was found to be a prevalent parasite and substantial genetic diversity was detected. Most rats were infected with a genotypic mixture of parasites. A hierarchical analysis of the genetic variation found in S. ratti sampled across Britain and Germany showed that 73.3% was explained by variation between parasites within individual hosts and 25.3% by variation between rats within sample sites. Only a small proportion (1.4%) of the total genetic variation was attributable to genetic subdivision between sample sites, suggesting that there is substantial gene flow between these sites. Most parasites sampled were found to exist in Hardy-Weinberg equilibrium and this population genetic structure is discussed in view of the virtual absence of sexual reproduction.     

Sex differences in the allocation of pay.

Examined the possibility that relative to males, females perceive less of a connection between their work and monetary rewards. In Study 1, 66 females and 60 males (respondents to an advertisement in a student newspaper) determined either their own pay or the pay of another person. Results support the hypothesis in that females paid themselves less than did males and less than other people (males or females) paid females. Results also suggest that Ss were more generous when they paid females. In Study 2, sex differences in self-pay were examined in 80 1st-, 4th-, 7th-, and 10th-grade Ss. Results replicate those of Study 1, in that at every grade level, females paid themselves less than did males. In addition, the extent to which females allocated pay the way their male counterparts did was highly related to the masculinity of their career goals. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The localization and functional significance of arylsulfatases in parasitic sarcosporidian protozoa in the tissue-cyst life cycle phase

Ten patients with perennial allergic rhinitis and 10 healthy subjects were studied to determine most discriminative nasal irrigation fluid marker(s) and to compare samples that were collected at baseline and over a 1-hour period, every 15 minutes. The latter were pooled and designated 1-hour sample. In the nasal irrigation we investigated the following inflammatory cells and soluble mediators: eosinophils, neutrophils, granulocyte-macrophage colony-stimulating factor, interleukin-4, interleukin-6, interleukin-8, ECP, EPX, MPO, leukotriene C4, leukotriene B4, prostaglandin E2, tryptase and fibrinogen. Patients with PAR were then treated for 2 weeks with the topical nasal steroid. The only marker that discriminated patients with perennial allergic rhinitis and healthy subjects was eosinophil count (EO%): correspondingly 14.01 +/- 5.8 and 0.18 +/- 0.09, (M +/- SD). Difference between the studied groups did not depend on the time of irrigation, baseline or 1-hour. EO% was also the only marker of a clinically successful treatment with the nasal steroid, 14.01 +/- 5.8 and 0.87 +/- 0.4, before and after treatment respectively. We conclude that EO% is the most sensitive inflammatory marker of perennial allergic rhinitis, and that baseline nasal irrigation can be used to study nasal mucosal inflammation.     

Sex differences in empathy and related behaviors.

According to the prevailing cultural stereotype as well as various psychological theories, empathy (the vicarious affective response to another person's feelings) is more prevalent in females than in males. A review of the research indicates that females do indeed appear to be more empathic than males. They do not appear to be more adept at assessing another person's affective, cognitive, or spatial perspective, however. There is also evidence to suggest that empathy in females may be part of a prosocial affective orientation that includes the tendency to experience guilt over harming others, but it does not, at least in early childhood, appear to be part of a larger interpersonal sensitivity that includes egocentric concerns about the feelings of others toward the self. It is suggested that females may have greater tendency to imagine themelves in the other's place, whereas males have more of a set toward instrumental ameliorative action. (71 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic epidemiology of parasitic protozoa and other infectious agents: the need for an integrated approach

This paper emphasises the relevance of the concepts and methods of evolutionary genetics for studying the epidemiology of parasitic protozoa and other pathogenic agents. Population genetics and phylogenetic analysis both contribute to identifying the relevant evolutionary and epidemiologically discrete units of research (Discrete typing units = DTUs), that can be equated to distinct phylogenetic lines. It is necessary (i) to establish that a given species represents a reliable DTU; (ii) to see whether a given species is further structured into lower DTUs that correspond to either clonal lineages or to cryptic species, and could exhibit distinct biomedical properties (virulence, resistance to drugs, etc). DTUs at the species and subspecies level can be conveniently identified by specific genetic markers or sets of genetic markers ("tags") for epidemiological follow-up. For any kind of pathogen (protozoa, fungi, bacteria, viruses), DTUs represent the relevant units of research, not only for epidemiology, but also, for other applied researches (clinical study, pathogenicity, vaccine and drug design, immunology, etc). The development of an "integrated genetic epidemiology of infectious diseases", that would explore the respective role of, and the interactions between, the genetic diversity (and its biological consequences) of the pathogen, the host and the vector (in the case of vector-borne diseases) is called for.     

Sex differences in empathy and related capacities.

Reviews the literature on sex differences in empathy (defined as vicarious affective responding to the emotional state of another) and related capacities (affective role taking and decoding of nonverbal cues). The literature is discussed according to method used to assess empathy and affective role taking. Where appropriate, meta-analyses were also computed. In general, sex differences in empathy were found to be a function of the methods used to assess empathy. There was a large sex difference favoring women when the measure of empathy was self-report scales; moderate differences (favoring females) were found for reflexive crying and self-report measures in laboratory situations; and no sex differences were evident when the measure of empathy was either physiological or unobtrusive observations of nonverbal reactions to another's emotional state. Moreover, few sex differences were found for children's affective role taking and decoding abilities. (156 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estimating sequestered parasite population dynamics in cerebral malaria

Clinical investigation of malaria is hampered by the lack of a method for estimating the number of parasites that are sequestered in the tissues, for it is these parasites that are thought to be crucial to the pathogenesis of life-threatening complications such as cerebral malaria. We present a method of estimating this hidden population by using clinical observations of peripheral parasitemia combined with an age-structured mathematical model of the parasite erythrocyte cycle. Applying the model to data from 217 Gambian children undergoing treatment for cerebral malaria we conclude that although artemether clears parasitemia more rapidly than quinine, the clearance of sequestered parasites is similar for the two drugs. The estimated sequestered mass was found to be a more direct predictor of fatal outcome than clinically observed parasitemia. This method allows a sequential analysis of sequestered parasite population dynamics in children suffering from cerebral malaria, and the results offer a possible explanation for why artemether provides less advantage than might have been expected over quinine in reducing mortality despite its rapid effect on circulating parasites.     

Sex differences in reward allocation: Subjects, partners, and tasks.

Numerous studies have shown that males tend to allocate a reward equitably, whereas females will divide the same reward equally. This result has been attributed to a fundamental difference in the preferred social orientations of the sexes. Two studies (156 female and 143 male undergraduates) hypothesized and found that this difference may be due to the use of masculine sex-linked tasks in prior research. In both studies, males allocated equitably and females equally with same-sex partners on a masculine task. On a sex-appropriate task, both sexes allocated equitably. Questionnaire measures suggested that this effect stemmed from differences in how male and female Ss evaluated their performance, depending on whether the task was congruent or incongruent. It was also found that both sexes allocated more generously to an opposite-sex partner than a same-sex partner regardless of task type or success/failure. These findings are interpreted in terms of the implications of viewing sex differences as situation-specific rather than general. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in children's reward allocation under competitive and cooperative instructional sets.

Using 136 5th and 6th graders, it was observed that males, but not females, gave fewer rewards to a hypothetical competitor presented as being more productive than themselves than they gave to themselves when they were described as the more productive opponent. No sex differences in allocation behavior were found under conditions of cooperation. It is concluded that gender differences in judgments of what constitutes a fair distribution of rewards are well established by age 11 yrs, even under hypothetical conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separation and characterization of two related giardiaviruses in the parasitic protozoan Giardia lamblia

Giardiavirus encapsidates a 6.2-kb double-stranded (ds) RNA within a capsid that consists of a major 100-kDa capsid protein (p100) and a minor 190-kDa protein (p190). In this study, two nonhomologous 6.2-kb ds RNAs cohabiting in Giardia lamblia trophozoites were found to be separately encapsidated into two distinct virions, one (designated GLV[p100]) whose capsid consists of p100 and p190, and the other (designated GLV[p95]) whose capsid consists of a 95-kDa protein (p95) and a minor p190-equivalent protein. Both types of virions were enriched in the membranous fraction of a lysate from virus-infected G. lamblia cells. Separation of these virions was achieved by CsCl gradient centrifugation following osmotic rupture of the viral particles. By these treatments, the 6.2-kb ds RNA was removed from GLV[p100] whereas that in GLV[p95] remained unchanged, and the two 6.2-kb ds RNAs that had been purified by this protocol displayed differential hybridization properties to viral cDNA probes. Western blotting and peptide mapping experiments show that p100 and p95 were closely related proteins, but each had distinct amino acid sequences. Virus purification and pulse-chase experiments show that GLV[p100] was selectively secreted into the medium whereas GLV[p95] remained within the trophozoites of G. lamblia toward the late phase of cell growth. Secretion of GLV[p100] was not inhibited by Brefeldin A. These findings demonstrate the cohabitation of multiple Giardiavirus species in G. lamblia.     

Sex differences in schizotypal personality in a nonclinical population.

This study tests the hypothesis that normal women will score higher on the more "positive" features of schizotypal personality and normal men will score higher on more "negative" schizotypal features. Two samples (n?=?393, 394) were administered the Schizotypal Personality Questionnaire, which contains subscales corresponding to the 9 schizotypal personality traits outlined in the Diagnostic and Statistical Manual of Mental Disorders-III—Revised (DSM-III—R). Women scored significantly higher on the positive subscales of Ideas of Reference and Odd Beliefs/Magical Thinking, and men scored significantly higher on the negative subscales of No Close Friends and Constricted Affect. These findings replicated from one sample to another. These results are broadly consistent with previous findings on schizotypal personality and schizophrenia. It is hypothesized that sex differences in schizophrenic symptomatology may in part reflect an exaggeration of normal sex difference in the general population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Host movement and the genetic structure of populations of parasitic nematodes

Mitochondrial DNA (mtDNA) sequence data were used to compare the population genetic structures of five species of parasitic nematodes from three different hosts: Ostertagia ostertagi and Haemonchus placei from cattle, H. contortus and Teladorsagia circumcincta from sheep, and Mazamastrongylus odocoilei from white-tailed deer. The parasites of sheep and cattle showed a pattern consistent with high gene flow among populations. The parasite of deer showed a pattern of substantial population subdivision and isolation by distance. It appears that host movement is an important determinant of population genetic structure in these nematodes. High gene flow in the parasites of livestock also indicates great opportunity for the spread of rare alleles that confer resistance to anthelmintic drugs. All species, including the parasite of deer, had unusually high within-population diversities (averages of 0.019-0.027 substitutions per site between pairs of individuals from the same population). Large effective population sizes (Ne), perhaps in combination with rapid mtDNA evolution, appear to be the most likely explanation for these high within-population diversities.     

Anemia and malaria in a Yanomami Amerindian population from the southern Venezuelan Amazon

OBJECTIVE: To review experience with 20 women treated for sciatic hernia between 1993 and 1997. METHODS: Patients with chronic pelvic pain and sciatic hernias, identified retrospectively from chart review, were seen during a 46-month period that covered the surgical experience at our institution and included approximately 1100 cases. The median length of follow-up was 13 months (range 3-36). RESULTS: Sciatic hernia was diagnosed in 20 white women with chronic pelvic pain and was treated using laparoscopy. In 14 cases the hernias were right sided, in five they were left sided, and in one they were bilateral. All sciatic hernias contained the ipsilateral ovary alone or with its fallopian tube. All 20 patients reported symptomatic relief at follow-up. CONCLUSION: Sciatic hernia is a cause of chronic pelvic pain and should be considered in the differential diagnosis.     

Sex differences in personality structure at age 14.

Although much work has been published on differences between the sexes in Western countries on tests of abilities, interests, and personality traits, little attention has been paid to comparing the organization or structuring of psychological variables among males and females. 198 male and 189 female Canadian 8th graders were given a battery of tests (e.g., the Safran Student's Interest Inventory and the Embedded Figures Test). Results indicate that the ability factors in the 2 sexes were closely similar, although their relations to age, artistic and scientific interests, social attitudes, personality tendencies, and other variables often differed markedly. For example, large sex differences in the psychological significance of field independence and of divergent thinking, and the organization of career and other interests indicate that mixed-sex studies should be discouraged. (French summary) (28 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The urbanization and demographic structure of population

Analyzes the effects of urbanization on the demographic structure of population. An increase in the degree of urbanization was found to be paralleled by an increase of the age qualification and of the migration activity of the population. The national composition of the population does not depend on urbanization.     

Sex ratio adjustment in relation to paternal attractiveness in a wild bird population

When the relative fitness of sons and daughters differs, sex-allocation theory predicts that it would be adaptive for individuals to adjust their investment in different sexes of offspring. Sex ratio adjustment by females in response to the sexual attractiveness of their mate would be an example of this. In vertebrates the existence of this form of sex ratio adjustment is controversial and may be confounded with sex-biased mortality, particularly in sexually size-dimorphic species. Here we use PCR amplification of a conserved W-chromosome-linked gene to show that the sex ratio within broods of a natural population of sexually size-monomorphic collared flycatchers Ficedula albicollis is related to the size of their father's forehead patch, a heritable secondary sexual character implicated in female choice. Experimental manipulations of paternal investment, which influence the size of his character in future breeding attempts, result in corresponding changes in the sex ratio of offspring born to males in those breeding attempts. In contrast, manipulations of maternal investment have no effect on future sex ratios, and there is no relationship between variables predicting the reproductive value of the brood and nestling sex ratio. Analysis of recruitment of offspring reveals similar patterns of sex ratio bias. The results suggest that female collared flycatchers be able to adjust the sex ratio of eggs ovulated in response to the phenotype of their mate. This finding is most consistent with "genetic quality" models of sexual selection.