Timing of reproductive maturation in rural versus urban Tonga boys, Zambia

Assessing Diet and Nutritional Intake of Rural Children in Zambia Using a Food Frequency Questionnaire

In this survey, to assess the energy and nutrient intake of rural children in Zambia, a semi-quantitative food frequency questionnaire (FFQ) was developed using the direct weighing method for 126 children, and then a dietary survey with 153 children was conducted using the FFQ. The dietary survey revealed that rural children in Zambia are deficient in energy intake compared to international standards. However, the protein intake met the recommended level; most of it came from vegetables. The carbohydrate intake rate was high, while the fat intake rate was relatively low because of a diet that was highly dependent on maize.

Sex differences in adipose development in a hunter-gatherer population

OBJECTIVE

Humans are unusually sexually dimorphic in body composition, with adult females having on average nearly twice the fat mass as males. The development of adipose sex differences has been well characterized for children growing up in food-abundant environments, with less known about cross-cultural variation, particularly in populations without exposure to market foods, mechanized technologies, schooling, vaccination, or other medical interventions.

METHODS

To add to the existing cross-cultural data, we fit multiple growth curves to body composition and anthropometric data to describe adipose development for the Savanna Pumé, South American hunter-gatherers.

RESULTS

(1) Little evidence is found for an adiposity 'rebound' at the end of early childhood among either Savanna Pumé girls or boys. (2) Rather, fat deposition fluctuates during childhood, from age ~4 to ~9 years, with no appreciable accumulation until the onset of puberty, a pattern also observed among Congo Baka hunter-gatherers. (3) Body fat fluctuations are more pronounced for girls than boys. (4) The age of peak skeletal, weight, and adipose gains are staggered to a much greater extent among the Savanna Pumé compared to the National Health and Nutrition Examination Survey (NHANES III) reference, suggesting this is an important developmental strategy in lean populations.

CONCLUSION

Documenting growth patterns under diverse preindustrial energetic conditions provides an important baseline for understanding sex differences in body fat emerging today under food abundance.

Evaluation of the nutritional status of rural children living in Zambia

Background

Growth references (growth charts) are used to assess the nutritional and growth status of children. In developed countries, there are growth charts based on the country’s national surveys. However, many developing countries do not have their own growth references, so they usually use WHO and US CDC references. In such cases, it is known that the growth statuses of the subject are underestimated or overestimated. This study sought to accurately assess the growth status of children by developing a local growth chart for children living in the Southern Province of Zambia.

Methods

Anthropometric measurements were conducted on 1135 children aged 2–19 years in the target area. The height and weight data for each sex and age were smoothed using the LMS method, and a percentile curve of height and weight was developed. Based on the US CDC reference, three indicators of undernutrition (stunting, underweight, and thinness) were calculated to determine the proportion of those who are undernourished (z-score < − 2).

Results

The 50th percentile curve of height and weight in the growth chart of the target population was equivalent to the 5–25th percentile curve of the US reference, and the children of Zambia were both small and of low weight. Conversely, although many subjects are small and of low weight, it was found that there were few poor nutritional statuses as judged by BMI. Through comparison with a previous study in the Southern Province of Zambia, a secular change in the growth of children over 20 years was found. Although there was no significant increase in height and weight in the older age group, there was a significant increase in height and weight at an earlier age. This is thought to be due to an increase in the growth rate of children due to improved socioeconomic conditions, women’s education level, and improvement in health care standards.

Conclusions

The subjects were small and of low weight compared to the US population, but the nutritional status was not poor by BMI. The height and weight at an earlier age increased compared to 20 years ago.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40101-020-00244-8.

Timing of and factors associated with HIV disclosure among perinatally infected children in rural Zambia

OBJECTIVE

This study was conducted to understand the process of disclosure among HIV-infected children receiving care in rural Zambia.

DESIGN

Cross-sectional and longitudinal analyses were conducted within an ongoing clinical cohort study of HIV-infected children receiving care in Macha, Zambia from 2007 to 2016.

METHODS

Children receiving HIV care were enrolled into the cohort study and assessed every 3 months. At each study visit, disclosure status was ascertained through questionnaire. Disclosure was categorized as none (child did not know they were chronically ill), partial (child knew they were chronically ill but not of their HIV infection status), or full (child knew they had HIV infection). Barriers to disclosure, and the timing of and factors associated with disclosure, were evaluated among children 5-15 years of age.

RESULTS

At study entry, the prevalence of full disclosure increased with age, from 2.1 to 76.2% among children 5-6 and 13-15 years of age, respectively. Reasons provided by caregivers for not disclosing the child's status included they felt the child was too young, they were afraid to, or they did not know how to tell the child. During follow-up, the median age at full disclosure was 9.0 years. Among children with full disclosure, 89.5% first had partial disclosure at a median age of 7.4 years. Factors associated with disclosure included being female, sharing responsibility for taking their own medication, and low weight-for-age z-score.

CONCLUSION

Given the complexity of the disclosure process and potential for health benefits, interventions and protocols are needed to support caregivers through the disclosure process.

Testosterone is positively and estradiol negatively associated with mucosal immunity in Amazonian adolescents

OBJECTIVES

A core assumption of life history theory and the immunocompetence handicap hypothesis (ICHH) is that testosterone (T) upregulates energetic investment in mating effort at the expense of immunity. This tenet, along with observed positive relationships between estrogens and immunity, may contribute to the higher observed morbidity and mortality of males. In the present study, we examine the association between sex steroid hormones and mucosal immunity as well as sex differences in immunity in a rural Amazonian population of immune-challenged Bolivian adolescents.

METHODS

Salivary steroid hormones (T [males only] and estradiol [E₂ , females only]), Tsimane-specific age-standardized BMI z-scores, and salivary mucosal immunity (sIgA, secretory IgA) were measured in 89 adolescent males and females.

RESULTS

Males had significantly higher sIgA levels than females, which may be due to the observed immune-endocrine associations found in the present study. Controlling for age and phenotypic condition, higher T significantly predicted higher sIgA; whereas higher E₂ was associated with lower sIgA in females.

CONCLUSIONS

Results stood in contrast to common interpretations of the ICHH, that is, that T should be inversely associated with immunity. Findings from the present study support the notion that the endocrine system likely affects immunity in a regulatory fashion, upregulating certain aspects of immunity while downregulating others. An important remaining question is the adaptive reason(s) for sex differences in endocrine-mediated immuno-redistribution.

Voice Mutation During Adolescence in Mangalore, India: Implications for the Assessment and Management of Mutational Voice Disorders

BACKGROUND

The knowledge of vocal mutation is important for speech pathologists in the diagnosis and management of individuals with mutational voice disorders. However, data on vocal mutation in the Indian population are scarce and hence the present study was planned to investigate the age of attainment of vocal mutation in boys and girls from Mangalore, India, in the age range of 8-18 years.

METHODS

A total of 600 participants in the age range of 8-18 years were divided into 10 groups with a 1-year interval. Sustained phonation /a/ and a narration were recorded. Two-way analysis of variance was used to obtain significant difference between the means across age and gender for the fundamental frequency and formant frequency measures.

RESULTS

There was significant main effect of groups for fundamental frequency measure in boys, with post hoc tests revealing statistically significant differences from 14 years of age onward. However, the cutoff criteria of 140 Hz in boys and 240 Hz in girls were attained only by 16 years of age in boys and 15 years in girls, indicating that 16 and 15 years as the ages of onset of vocal mutation in boys and girls, respectively. Results also revealed that first formant frequency undergoes changes from 13 years onward. However, F2 changes from 16 years of age, with no significance observed in F3.

CONCLUSION

The results of the present study are useful in the assessment and management of individuals with mutational voice disorders.

Anthropometric Measurements, Serum Reproductive Hormonal Levels and Sexual Development among Boys in the Rural Western Cape, South Africa

Data on growth and sexual maturation among boys from the rural Western Cape in South Africa is limited. A cross-sectional study of 269 school boys was conducted testing for serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, sex hormone binding globulin (SHBG) and estradiol (E2); height, weight and body mass index (BMI); sexual maturity (using Tanner Stages) and a questionnaire (demographic and medical history). The median age at pubertal onset (Tanner Stage 2) and Tanner Stage 5 was 11.6 and 14.7 years, respectively. The median testicular volume was 5.5 mL at Tanner Stage 2 increasing from 2.5 mL at Tanner Stage 1 to 14.7 mL at Tanner Stage 5. Height and weight measurements were <25th & 50th percentile references at Tanner Stages 1–3. Controlling for confounders, serum FSH and LH increased (p < 0.05) from Tanner Stage 1 to 4 (by 4.1 and 3 mL respectively), and serum testosterone and estradiol increased after Tanner Stage 2 (by 12.7 nmol/L and 59.5 pmol/L respectively). These results indicate some delays in pubertal development of boys in the rural Western Cape when compared to boys from other settings possibly due to nutritional, socio-economic and environmental exposures. Changes in serum hormone levels were consistent with other populations. Initiatives to improve nutrition amongst Western Cape rural communities are recommended.

Trends in mortality from septicaemia and pneumonia with economic development: an age-period-cohort analysis

Background

Hong Kong population has experienced drastic changes in its economic development in the 1940s. Taking advantage of Hong Kong’s unique demographic and socioeconomic history, characterized by massive, punctuated migration waves from Southern China, and recent, rapid transition from a pre-industrialized society to the first ethnic Chinese community reaching “first world” status over the last 60 years (i.e., in two or three generations), we examined the longitudinal trends in infection related mortality including septicemia compared to trends in non-bacterial pneumonia to generate hypotheses for further testing in other recently transitioned economies and to provide generalized aetiological insights on how economic transition affects infection-related mortality.

Methods

We used deaths from septicemia and pneumonia not specified as bacterial, and population figures in Hong Kong from 1976–2005. We fitted age-period-cohort models to decompose septicemia and non-bacterial pneumonia mortality rates into age, period and cohort effects.

Results

Septicaemia-related deaths increased exponentially with age, with a downturn by period. The birth cohort curves had downward inflections in both sexes in the 1940s, with a steeper deceleration for women. Non-bacterial pneumonia-related deaths also increased exponentially with age, but the birth cohort patterns showed no downturns for those born in the 1940s.

Conclusion

The observed changes appeared to suggest that better early life conditions may enable better development of adaptive immunity, thus enhancing immunity against bacterial infections, with greater benefits for women than men. Given the interaction between the immune system and the gonadotropic axis, these observations are compatible with the hypothesis that upregulation of the gonadotropic axis underlies some of the changes in disease patterns with economic development.

Demographic differences in self-report pubertal status among rural adolescents in the US

BACKGROUND

While sex and racial/ethnic differences in pubertal development have been noted, most of this research has been in urban areas.

AIM

The purpose of this study is to examine demographic differences in pubertal status among a school-based sample of US rural adolescents aged 11-17 (n = 6425).

METHODS

Pubertal status was measured using the Pubertal Development Scale (PDS), a self-report scale of secondary sexual characteristics. This study compared pubertal status means by age, sex and race/ethnicity.

RESULTS

At all ages, females had a higher mean pubertal status than males. Most racial/ethnic differences were between White and Black youth. Between the ages of 11 and 13, Black youth reported more advanced development than White youth. However, contrary to research with urban samples, this pattern of development reversed in later adolescence and the reversal was more prominent among males than females. Although there were no differences in pubertal status between White and Latino males, White females had higher mean levels of development than Latino females.

CONCLUSION

Demographic patterns were both consistent with and different from previous research with urban adolescents, suggesting the need for comparison of demographic patterns of pubertal development in samples that include youth from urban and rural areas.

A secular trend toward earlier male sexual maturity: evidence from shifting ages of male young adult mortality

This paper shows new evidence of a steady long-term decline in age of male sexual maturity since at least the mid-eighteenth century. A method for measuring the timing of male maturity is developed based on the age at which male young adult mortality accelerates. The method is applied to mortality data from Sweden, Denmark, Norway, the United Kingdom, and Italy. The secular trend toward earlier male sexual maturity parallels the trend toward earlier menarche for females, suggesting that common environmental cues influence the speed of both males' and females' sexual maturation.

How young is "too young"? Comparative perspectives on adolescent sexual, marital, and reproductive transitions

This study puts forth three criteria for assessing the extent to which the timing of sexual, marital, and reproductive transitions among male and female adolescents could be considered "too young": (1) the physiological maturation of the body; (2) the cognitive capacity for making safe, informed, and voluntary decisions; and (3) institutionalized concepts of "old enough" for consent to sexual intercourse and marriage as reflected in legal frameworks and international standards. Expansion of the age grouping of adolescence is proposed, from the customary 15-19 into three age categories--early adolescence (ages 10-14, or 10-11 and 12-14), middle adolescence (15-17), and late adolescence (18-19)--to better capture the age-specific variations in the trajectories of male and female sexual, marital, and reproductive events. An application of the three adolescent development criteria to the timing of transitions observed in Demographic and Health Surveys in 64 developing countries leads to the conclusion that boys and girls aged 14 and younger are universally "too young" to make safe and consensual transitions; that 15-17-year-olds may or may not be too young, depending on their circumstances; and that 18-year-olds are generally "old enough." Policies and programs should focus on capacity building and the creation of an enabling environment for making safe and voluntary transitions among all age groups, but particularly among 10-14-year-olds, whose sexual and reproductive health and rights are so clearly at stake.

Does economic development contribute to sex differences in ischaemic heart disease mortality? Hong Kong as a natural experiment using a case-control study

BACKGROUND

The male excess risk of premature ischemic heart disease (IHD) mortality may be partially due to an unknown macro-environmental influence associated with economic development. We examined whether excess male risk of IHD mortality was higher with birth in an economically developed environment.

METHODS

We used multivariable logistic regression in a population-based case-control study of all adult deaths in Hong Kong Chinese in 1998 to compare sex differences in IHD mortality (1,189 deaths in men, 1,035 deaths in women and 20,842 controls) between Hong Kong residents born in economically developed Hong Kong or in contemporaneously undeveloped Guangdong province in China.

RESULTS

Younger (35-64 years) native-born Hong Kong men had a higher risk of IHD death than such women (odds ratio 2.91, 95% confidence interval 1.66 to 5.13), adjusted for age, socio-economic status and lifestyle. There was no such sex difference in Hong Kong residents who had migrated from Guangdong. There were no sex differences in pneumonia deaths by birth place.

CONCLUSION

Most of these people migrated as young adults; we speculate that environmentally mediated differences in pubertal maturation (when the male disadvantage in lipids and fat patterning emerges) may contribute to excess male premature IHD mortality in developed environments.

Growth environment and sex differences in lipids, body shape and diabetes risk

Background

Sex differences in lipids and body shape, but not diabetes, increase at puberty. Hong Kong Chinese are mainly first or second generation migrants from China, who have shared an economically developed environment for years, but grew up in very different environments in Hong Kong or contemporaneously undeveloped Guangdong, China. We assessed if environment during growth had sex-specific associations with lipids and body shape, but not diabetes.

Methodology and Principal Findings

We used multivariable regression in a population-based cross-sectional study, undertaken from 1994 to 1996, of 2537 Hong Kong Chinese residents aged 25 to 74 years with clinical measurements of ischaemic heart disease (IHD) risk, including HDL-cholesterol, ApoB, diabetes and obesity. Waist-hip ratio was higher (mean difference 0.01, 95% CI 0.001 to 0.02) in men, who had grown up in an economically developed rather than undeveloped environment, as was apolipoprotein B (0.05 g/L, 95% CI 0.001 to 0.10), adjusted for age, socio-economic status and lifestyle. In contrast, the same comparison was associated in women with lower waist-hip ratio (−0.01, 95% CI −0.001 to −0.02) and higher HDL-cholesterol (0.05 mmol/L, 95% CI 0.0004 to 0.10). The associations in men and women were significantly different (p-values<0.001). There were no such differences for diabetes.

Conclusions

Growth in a developed environment with improved nutrition may promote higher sex-steroids at puberty producing an atherogenic lipid profile and male fat pattern in men but the opposite in women, with tracking of increased male IHD risk into adult life.

Cross-cultural Comparison of Learning in Human Hunting : Implications for Life History Evolution

This paper is a cross-cultural examination of the development of hunting skills and the implications for the debate on the role of learning in the evolution of human life history patterns. While life history theory has proven to be a powerful tool for understanding the evolution of the human life course, other schools, such as cultural transmission and social learning theory, also provide theoretical insights. These disparate theories are reviewed, and alternative and exclusive predictions are identified. This study of cross-cultural regularities in how children learn hunting skills, based on the ethnographic literature on traditional hunters, complements existing empirical work and highlights future areas for investigation.

Reproductive maturation, somatic growth and testosterone among Zimbabwe boys

BACKGROUND

Little is known about the role of energetic status in the timing of puberty among males across populations.

AIM

To determine the relationship of testosterone production and bioavailability to energetic status and somatic growth in a sub-Saharan population.

SUBJECTS AND METHODS

Anthropometric measures, secondary sexual characteristics, blood spot and salivary samples were obtained from 441 Zimbabwe school boys, aged 12-18, from four high schools in the Harare area.

RESULTS

Salivary and blood testosterone both showed their first significant increase between 14 and 15 years of age. Both salivary and blood testosterone were positively related to subscapular, but not triceps skinfold, when controlled for Tanner genital stage and age. Controlled for Tanner genital stage and age, salivary, but not blood testosterone was related to suprailiac skinfolds. Blood testosterone, but not salivary testosterone, showed a significant relationship with Tanner genital stage, controlled for age and suprailic skinfolds. Blood and salivary testosterone showed similar relationships with height and arm muscle plus bone area.

CONCLUSION

These results provide support for the hypothesis that energetic status, especially abdominal fat plays a role in bioavailable testosterone during male puberty. However, they fail to demonstrate a clear effect of bioavailable testosterone on somatic growth.

Pubertal timing, hormones, and body composition among adolescent Turkana males

The Turkana, like other East African pastoral groups, are known for their tall adult stature, achieved despite a blunted growth spurt during adolescence and continued growth into the early 20s. To investigate the hormonal mechanisms associated with the pattern of slow and continued adolescent growth, we collected data on hormonal status, height, weight, and trunk skinfolds and ethnographic self-reports of testicular maturation in a cross-sectional sample of 35 nomadic and 37 settled Turkana males aged 14-24. Hormonal determinations included testosterone (T), sex hormone-binding globulin (SHBG), and dehydroepiandrosterone (DHEA) in blood, in addition to urinary DHEA. Self-reports of testicular maturation showed no difference between settled and nomadic subpopulations. However, nomadic boys exhibited significantly higher levels of T, DHEA, and SHBG. Of all the hormones, only SHBG showed a significant relationship with age. Multiple regression models show blood T and SHBG to be significant independent predictors of achieved height as well as weight, controlling for age. Our results suggest that onset of puberty is substantially delayed among Turkana males, and that bioavailable T is related to growth in stature during adolescence. We suggest that SHBG acts to mediate the effects of energy availability on adolescent growth in this energetically limited population. Our findings may also have implications for understanding adolescent growth among Homo erectus.

Timing of pubertal maturation and the onset of sexual behavior among Zimbabwe school boys

The relationship between reproductive maturation and the onset of sexual behavior in boys across cultures is unclear. To explore the relative timing of pubertal events and their relationship to the onset of sexual behavior, we used data collected from 442 Zimbabwe school boys aged 12-18 years. Measures of reproductive maturation included self-reported spontaneous nocturnal emission, secondary sexual characteristics, and salivary testosterone. Behavioral measures included age at first sexual fantasies, non-coital sexual behavior, and coitus. Sigmoid interpolation curve techniques indicated a median age of first erection at 10.75 +/- 0.11 years, first sexual fantasy at 12.66 +/- 0.03 years, first spontaneous nocturnal emission at 13.02 +/- 0.03 years, and adult levels of blood testosterone at 17.2 +/- 0.7 years. First reported spontaneous nocturnal emission was significantly related to all measures of sexual behavior. Multiple regression models indicated that first reported spontaneous nocturnal emission was a stronger predictor of sexual behavior than variation in secondary sexual characteristics. In addition, testosterone was a significant predictor of sexual fantasies and intercourse, independent of first reported spontaneous nocturnal emission. These results confirm earlier findings in other populations that self-reported spontaneous nocturnal emissions can be used as a marker of pubertal timing among adolescent boys. They also suggest that variation in testosterone plays a role in the onset of sexual behavior among boys, beyond its relationship to developmental timing. The behavioral mechanisms represented by the significant effects of testosterone reported here remain to be investigated.