scholarly journals Human Resistance to Plasmodium falciparum Increases during Puberty and Is Predicted by Dehydroepiandrosterone Sulfate Levels

2001 ◽  
Vol 69 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Jonathan D. Kurtis ◽  
Ramadhan Mtalib ◽  
Frederick K. Onyango ◽  
Patrick E. Duffy
Keyword(s):  
Plasmodium Falciparum ◽  
Parasite Density ◽  
Pubertal Development ◽  
Dehydroepiandrosterone Sulfate ◽  
Young Males ◽  
Tanner Staging ◽  
Age Related ◽  
Blood Smears ◽  
Full Immunity ◽  
The Relationship

ABSTRACT Immunity to Plasmodium falciparum develops slowly in areas of endemicity, and this is often ascribed to poorly immunogenic or highly variant parasite antigens. However, among populations newly exposed to malaria, adults acquire immunity more rapidly than children. We examined the relationship between pubertal development and resistance to P. falciparum. During two transmission seasons in western Kenya, we treated the same cohort of young males to eradicate P. falciparum and then obtained blood smears each week for 4 months. We determined pubertal development by Tanner staging and by levels of dehydroepiandrosterone sulfate (DHEAS) and testosterone in plasma. In multivariate and age-stratified analyses, we examined the effect of pubertal development on resistance to malaria. In both seasons (n = 248 and 144 volunteers, respectively), older males were less susceptible than younger males. Age-related decreases in the frequency and density of parasitemia were greatest during puberty (15- to 20-year-olds). DHEAS and testosterone were significant independent predictors of resistance to P. falciparum parasitemia, even after accounting for the effect of age. Fifteen- to 20-year-old males with high DHEAS levels had a 72% lower mean parasite density (P < 0.01) than individuals with low DHEAS levels. Similarly, 21- to 35-year-old males with high DHEAS levels had a 92% lower mean parasite density (P < 0.001) and 48% lower frequency of parasitemia (P < 0.05) than individuals with low DHEAS levels. These data suggest that the long period needed to attain full immunity could be explained as a consequence of host development rather than as the requirement to recognize variant or poorly immunogenic parasite antigens.

scholarly journals High DHEAS Is Associated With Earlier Pubertal Events in Girls But Not in Boys

2017 ◽  
Vol 1 (7) ◽  
pp. 800-808 ◽  
Author(s):  
Ana Pereira ◽  
German Iñiguez ◽  
Camila Corvalan ◽  
Verónica Mericq
Keyword(s):  
Ovarian Function ◽  
Pubertal Development ◽  
Sex Characteristics ◽  
Premature Thelarche ◽  
Logistic Regression Models ◽  
Tanner Staging ◽  
Secondary Sex Characteristics ◽  
Premature Adrenarche ◽  
The Relationship

Context: Premature adrenarche (PA) has been associated with increased metabolic risk. Objective: To describe the risk of precocious thelarche (PT; &lt;8 years), pubarche (PP; girls &lt;8 years, boys &lt;9 years), and gonadarche (PG; &lt;9 years) in children with high dehydroepiandrosterone sulphate (DHEAS [HD]) vs those with normal DHEAS (ND). Setting and Intervention: Longitudinal Chilean cohort (n = 1052, 49.9% girls). Annual clinical examination including secondary sex characteristics by Tanner staging. Logistic regression models were adjusted by age and BMI. Main Outcome: Assess the relationship between DHEAS and premature thelarche, gonadarche, and pubarche in both sexes. Results: At age of DHEAS determination, overweight/obesity was present in 44.3% of boys and 42.9% of girls. Incidences of any precocious event were observed in 17.2% of boys and in 25.4% of girls, presented as 8.7% of PG and 8.5% of PP in boys and as 21.3% of PT and 4.1% of PP in girls. In crude and adjusted models in boys, HD did not increase the risk of earlier pubertal events. Conversely, girls with HD had a 2.6 times greater risk of early thelarche and a three times greater risk of early pubarche compared with girls with ND concentrations. Conclusion: In Chilean adolescents, precocious events of pubertal development were in line with the worldwide secular trend of earlier sexual maturation. HD was only associated with PT and PP in girls. Continuous follow-up of this cohort is a unique opportunity to prospectively address and analyze the interrelationships among HD, early growth, and adiposity as determinants of gonadarche, pubertal rate/sequence progression, and ovarian function.

scholarly journals Predicting the likelihood and intensity of mosquito infection from sex specific Plasmodium falciparum gametocyte density

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
John Bradley ◽  
Will Stone ◽  
Dari F Da ◽  
Isabelle Morlais ◽  
Alassane Dicko ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Parasite Density ◽  
Malaria Control ◽  
Complex Relationship ◽  
Gametocyte Density ◽  
Feeding Experiments ◽  
Male Parasite ◽  
The Mean ◽  
The Relationship ◽  
Mosquito Infection

Understanding the importance of gametocyte density on human-to-mosquito transmission is of immediate relevance to malaria control. Previous work (Churcher et al., 2013) indicated a complex relationship between gametocyte density and mosquito infection. Here we use data from 148 feeding experiments on naturally infected gametocyte carriers to show that the relationship is much simpler and depends on both female and male parasite density. The proportion of mosquitoes infected is primarily determined by the density of female gametocytes though transmission from low gametocyte densities may be impeded by a lack of male parasites. Improved precision of gametocyte quantification simplifies the shape of the relationship with infection increasing rapidly before plateauing at higher densities. The mean number of oocysts per mosquito rises quickly with gametocyte density but continues to increase across densities examined. The work highlights the importance of measuring both female and male gametocyte density when estimating the human reservoir of infection.

Cognitive Factors Mediate the Relation Between Age and Flight Path Maintenance in General Aviation

2016 ◽  
Vol 6 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Kathleen Van Benthem ◽  
Chris M. Herdman
Keyword(s):  
Cognitive Functioning ◽  
Flight Path ◽  
General Aviation ◽  
Cognitive Factors ◽  
Pilot Performance ◽  
Pilot Error ◽  
Age Related ◽  
And Performance ◽  
Relationship Of ◽  
The Relationship

Abstract. Identifying pilot attributes associated with risk is important, especially in general aviation where pilot error is implicated in most accidents. This research examined the relationship of pilot age, expertise, and cognitive functioning to deviations from an ideal circuit trajectory. In all, 54 pilots, of varying age, flew a Cessna 172 simulator. Cognitive measures were obtained using the CogScreen-AE ( Kay, 1995 ). Older age and lower levels of expertise and cognitive functioning were associated with significantly greater flight path deviations. The relationship between age and performance was fully mediated by a cluster of cognitive factors: speed and working memory, visual attention, and cognitive flexibility. These findings add to the literature showing that age-related changes in cognition may impact pilot performance.

The Association Between Cardio-Ankle Vascular Index and Primary Idiopathic Complete Atrioventricular Block in an Elderly Population

Angiology ◽  
2021 ◽  
pp. 000331972110287
Author(s):  
Turhan Turan ◽  
Faruk Kara ◽  
Selim Kul ◽  
Muhammet Rasit Sayın ◽  
Sinan Sahin ◽  
...  
Keyword(s):  
Arterial Stiffness ◽  
Atrioventricular Block ◽  
Elderly Population ◽  
Complete Atrioventricular Block ◽  
Age Related ◽  
And Gender ◽  
The Relationship ◽  
Block Frequency ◽  
Complete Atrioventricular ◽  
Relevant Factors

The most common cause of complete atrioventricular block (CAVB) is age-related fibrotic degeneration and is referred to as primary idiopathic complete atrioventricular block (iCAVB). This study aims to investigate the relationship between iCAVB and arterial stiffness using the cardio-ankle vascular index (CAVI). In this study, of 205 CAVB patients, 41 patients with iCAVB implanted with a dual-chamber permanent pacemaker and 40 age- and gender-matched controls were studied. Arterial stiffness was assessed by a VaSera VS-1000 CAVI instrument. The CAVI values of patients with iCAVB were significantly higher compared with the controls (9.63 ± 1.42 vs 8.57 ± 1.12, P < .001). Idiopathic complete atrioventricular block frequency was higher among patients with abnormal CAVI values than those with borderline and normal CAVI ( P = .04). In multivariate analysis, only CAVI was an independent predictor of iCAVB after adjusting for other relevant factors (odds ratio, 2.575; 95% CI [1.390-4.770]; P = .003). The present study demonstrated that CAVI, as a marker of arterial stiffness, was increased among elderly patients with iCAVB. Thus, we provide a possible additional mechanism linking easily measured CAVI with iCAVB.

scholarly journals Plasma angiopoietin-2 is associated with age-related deficits in cognitive sub-scales in Ugandan children following severe malaria

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Benson J. Ouma ◽  
Paul Bangirana ◽  
John M. Ssenkusu ◽  
Dibyadyuti Datta ◽  
Robert O. Opoka ◽  
...  
Keyword(s):  
Severe Malaria ◽  
Parental Education ◽  
Preschool Education ◽  
Kidney Injury ◽  
Malaria Episode ◽  
Enzyme Linked Immunosorbent Assay ◽  
Testing Time ◽  
Age Related ◽  
Angiopoietin 2 ◽  
The Relationship

Abstract Background Elevated angiopoietin-2 (Angpt-2) concentrations are associated with worse overall neurocognitive function in severe malaria survivors, but the specific domains affected have not been elucidated. Methods Ugandan children with severe malaria underwent neurocognitive evaluation a week after hospital discharge and at 6, 12 and 24 months follow-up. The relationship between Angpt-2 concentrations and age-adjusted, cognitive sub-scale z-scores over time were evaluated using linear mixed effects models, adjusting for disease severity (coma, acute kidney injury, number of seizures in hospital) and sociodemographic factors (age, gender, height-for-age z-score, socio-economic status, enrichment in the home environment, parental education, and any preschool education of the child). The Mullen Scales of Early Learning was used in children < 5 years and the Kaufman Assessment Battery for Children 2nd edition was used in children ≥ 5 years of age. Angpt-2 levels were measured on admission plasma samples by enzyme-linked immunosorbent assay. Adjustment for multiple comparisons was conducted using the Benjamini–Hochberg Procedure of False Discovery Rate. Results Increased admission Angpt-2 concentration was associated with worse outcomes in all domains (fine and gross motor, visual reception, receptive and expressive language) in children < 5 years of age at the time of severe malaria episode, and worse simultaneous processing and learning in children < 5 years of age at the time of severe malaria who were tested when ≥ 5 years of age. No association was seen between Angpt-2 levels and cognitive outcomes in children ≥ 5 years at the time of severe malaria episode, but numbers of children and testing time points were lower for children ≥ 5 years at the time of severe malaria episode. Conclusion Elevated Angpt-2 concentration in children with severe malaria is associated with worse outcomes in multiple neurocognitive domains. The relationship between Angpt-2 and worse cognition is evident in children < 5 years of age at the time of severe malaria presentation and in selected domains in older years.

The relationship between the age of Schistosoma mansoni cercariae and their ability to penetrate and infect the mammalian host

Parasitology ◽  
1983 ◽  
Vol 87 (3) ◽  
pp. 481-492 ◽  
Author(s):  
J. Ruth Lawson ◽  
R. A. Wilson
Keyword(s):  
Schistosoma Mansoni ◽  
Stratum Corneum ◽  
Mass Mortality ◽  
Mammalian Host ◽  
Energy Reserves ◽  
Age Related ◽  
Abdominal Route ◽  
Relationship Of ◽  
The Relationship ◽  
Related Mortality

SummaryThe ability of the cercariae of Schistosoma mansoni to penetrate the tails of mice was shown to remain constant throughout their lives. However, their capacity to establish themselves and then reach maturity decreased as they aged. The abdominal route of penetration produced consistently higher maturation rates than the tail route. Significantly different maturation rates were obtained by modifying the standard tail infection technique. Evidence is presented that age-related mortality of schisto-somula occurs within 24 h of penetration and may be associated with the exhaustion of energy reserves during the penetration of the stratum corneum. The relationship of this age-related mortality to ‘mass mortality’ is discussed.

scholarly journals Leptin and Aging: Correlation with Endocrine Changes in Male and Female Healthy Adult Populations of Different Body Weights

2000 ◽  
Vol 85 (5) ◽  
pp. 1954-1962 ◽  
Author(s):  
Andrea M. Isidori ◽  
Felice Strollo ◽  
Michele Morè ◽  
Massimiliano Caprio ◽  
Antonio Aversa ◽  
...  
Keyword(s):  
Plasma Levels ◽  
Linear Regression Analysis ◽  
Age Groups ◽  
Dehydroepiandrosterone Sulfate ◽  
Multiple Linear Regression Analysis ◽  
Multiple Regression Model ◽  
Sex Hormone Binding Globulin ◽  
Obese Women ◽  
Age Related ◽  
Plasma Leptin

Abstract Aging is associated with changes in plasma levels of several hormones. There are conflicting reports on whether circulating leptin levels change during aging, the possible explanation for which is that alterations in adiposity and body mass index (BMI) also occur. In this study we measured plasma leptin and other hormonal parameters known to influence leptin in 150 men and 320 women of a wide age (18–77 yr) and BMI (18.5–61.1 kg/m2) range. Subjects of each gender were separated into 2 groups of similar BMI, i.e. nonobese (BMI, &lt;30) and obese (BMI, &gt;30), and treated separately. Statistical analysis was performed, treating each group of subjects as a whole population or divided into age groups (&lt;30, 30–50, and &gt;50 yr). BMI-adjusted leptin levels were progressively lower with increasing age in women, with a consistent fall after menopause (−21%; P &lt; 0.001); in men, leptin levels also tended to be lower in subjects more than 50 yr of age, but the reduction was not significant. Multiple linear regression analysis, performed on subjects treated either as a whole population or divided into obese and nonobese, showed that in both genders BMI and age were independent contributors of leptin levels, and there was an inverse relationship between leptin and age in both obese (standardized coefficient β = −0.25 in women and −0.23 in men; P &lt; 0.01) and nonobese (−0.22 in women and −0.20 in men; P &lt; 0.05) subjects. The correlation of leptin and age with plasma levels of sex and thyroid hormones, GH, insulin-like growth factor I, PRL, and insulin was also evaluated. The variables that correlated with leptin were included in a multiple regression model that included BMI and age. Testosterone in men (−0.43 in nonobese and −0.19 in obese; P &lt; 0.05) and estradiol in women (0.22 in nonobese and 0.24 in obese; P &lt; 0.05) were important contributors to leptin levels; also, dehydroepiandrosterone sulfate in obese women (−0.16) and sex hormone-binding globulin in obese subjects of both genders (0.15 in women and 0.19 in men) were significant determinants in the model. However, none of the hormonal parameters abolished the negative correlation between leptin and age or the gender difference in leptin levels. In conclusion, our data show that in adult humans of different body weight, serum leptin gradually declines during aging; leptin reduction is higher in women than in men, but it is independent from BMI and other age-related endocrine changes.

Spatial memory in Canadian and Indian young and older adults: the effects of age, culture and cultural orientation

2021 ◽  
Author(s):  
Khushi Patel
Keyword(s):  
Older Adults ◽  
Spatial Memory ◽  
Cultural Orientation ◽  
Strategy Use ◽  
Age Related ◽  
Cultural Research ◽  
Cross Cultural Research ◽  
Context Specific ◽  
Performance Gains ◽  
The Relationship

Cross-cultural research suggests that individualistic Americans have a tendency to process focal objects; in contrast, collectivist Asians have a tendency to bind objects and context (Park & Huang, 2010). However, little is known whether the reported cultural differences are moderated by cultural orientation. In light of these results and the well-reported age-related decline in binding abilities, the current study examined cultural and age differences in cultural orientation, spatial memory and strategy use with young and older Canadian and Indian adults. There was little difference between Canadian and Indian participants’ cultural orientation. While cultural orientation did not moderate the relationship between culture and spatial memory, spatial memory and strategy use differed as a function of age. The use of context-specific strategies resulted in performance gains in older adults, however overall older adults had poor spatial memory, with Indian older adults scoring significantly lower than Canadian older adults on the courtyard task.

Sign in / Sign up

Export Citation Format

Share Document