Individual Biological Factors Research Articles

A gender perspective on diet, microbiome, and sex hormone interplay in cardiovascular disease.

A unique interplay between body and environment embeds and reflects host-microbiome interactions that contribute to sex-differential disease susceptibility, symptomatology, and treatment outcomes. These differences derive from individual biological factors, such as sex hormone action, sex-divergent immune processes, X-linked gene dosage effects, and epigenetics, as well as from their interaction across the lifespan. The gut microbiome is increasingly recognized as a moderator of several body systems that are thus impacted by its function and composition. In humans, biological sex components further interact with gender-specific exposures such as dietary preferences, stressors, and life experiences to form a complex whole, requiring innovative methodologies to disentangle. Here, we summarize current knowledge of the interactions among sex hormones, gut microbiota, immune system, and vascular health and their relevance for sex-differential epidemiology of cardiovascular diseases. We outline clinical implications, identify knowledge gaps, and place emphasis on required future studies to address these gaps. In addition, we provide an overview of the caveats associated with conducting cardiovascular research that require consideration of sex/gender differences. While previous work has inspected several of these components separately, here we call attention to further translational utility of a combined perspective from cardiovascular translational research, gender medicine, and microbiome systems biology.

Rumen fermentation parameters and papillae development in Simmental growing bulls with divergent residual feed intake

Residual feed intake (RFI), a widespread index used to measure animal feed efficiency, is influenced by various individual biological factors related to inter-animal variation that need to be assessed. Herein, 30 Simmental bulls, raised under the same farm conditions, were divided on the basis of RFI values into a high efficient group (HE, RFI = − 1.18 ± 0.33 kg DM/d, n = 15) and a low efficient group (LE, RFI = 0.92 ± 0.35 kg DM/d, n = 15). Subsequently, bulls were slaughtered at an average BW of 734 ± 39.4 kg. Their ruminal fermentation traits were analysed immediately after slaughtering and after 24 h of in vitro incubation. Furthermore, ruminal micro-biota composition and ruminal papillae morphology were examined. The LE group exhibited a higher propionate concentration as a percentage of total volatile fatty acids (17.3 vs 16.1%, P = 0.04) in the rumen fluid collected during slaughtering, which was also confirmed after in vitro fermentation (16.6 vs 15.4% respectively for LE and HE, P = 0.01). This phenomenon resulted in a significant alteration in the acetate−to−propionate ratio (A:P) with higher values for the HE group, both after slaughter (4.01 vs 3.66, P = 0.02) and after in vitro incubation (3.78 vs 3.66, P = 0.02). Methane production was similar in both groups either as absolute production (227 vs 218 mL for HE and LE, respectively) or expressed as a percentage of total gas (approximately 22%). Even if significant differences (P < 0.20) in the relative abundance of some bacterial genera were observed for the two RFI groups, no significant variations were observed in the alpha (Shannon index) and beta (Bray–Curtis index) diversity. Considering the papillae morphology, the LE subjects have shown higher length values (6.26 vs 4.90 mm, P < 0.01) while HE subjects have demonstrated higher papillae density (46.4 vs 40.5 n/cm2, P = 0.02). Histo-morphometric analysis did not reveal appreciable modifications in the total papilla thickness, boundaries or surface between the experimental groups. In conclusion, our results contribute to efforts to analyse the factors affecting feed efficiency at the ruminal level. Propionate production, papillae morphology and a few bacterial genera certainly play a role in this regard, although not a decisive one.

Confounding Factors Impacting microRNA Expression in Human Saliva: Methodological and Biological Considerations.

There is growing interest in saliva microRNAs (miRNAs) as non-invasive biomarkers for human disease. Such an approach requires understanding how differences in experimental design affect miRNA expression. Variations in technical methodologies, coupled with inter-individual variability may reduce study reproducibility and generalizability. Another barrier facing salivary miRNA biomarker research is a lack of recognized “control miRNAs”. In one of the largest studies of human salivary miRNA to date (922 healthy individuals), we utilized 1225 saliva samples to quantify variability in miRNA expression resulting from aligner selection (Bowtie1 vs. Bowtie2), saliva collection method (expectorated vs. swabbed), RNA stabilizer (presence vs. absence), and individual biological factors (sex, age, body mass index, exercise, caloric intake). Differential expression analyses revealed that absence of RNA stabilizer introduced the greatest variability, followed by differences in methods of collection and aligner. Biological factors generally affected a smaller number of miRNAs. We also reported coefficients of variations for 643 miRNAs consistently present in saliva, highlighting several salivary miRNAs to serve as reference genes. Thus, the results of this analysis can be used by researchers to optimize parameters of salivary miRNA measurement, exclude miRNAs confounded by numerous biologic factors, and identify appropriate miRNA controls.

The Potential of Systems Thinking in Tackling The Wicked Problem of Childhood Obesity in the Philippines

Obesity among children and adolescents in the Philippines has been on the rise over the last decade, and has been further exacerbated by the COVID-19 pandemic. Addressing the ‘wicked problem’ of obesity necessitates an approach that considers the complexity of multiple, interdependent factors at play in the obesogenic system. In current literature, there is a lack of system models that map out obesity systems in the Philippine context. Through a series of workshops involving three middle-income Southeast Asian countries, systems thinking principles and tools were applied to unpack a specific issue related to non-communicable diseases. A cross-sector, multidisciplinary team from the Philippines developed a causal loop diagram to map several contributing factors to childhood obesity in the country, such as individual biological factors, physical inactivity, child’s eating patterns, family lifestyle factors, food retail and advertisement, health literacy, and cultural influences. This exercise aimed to identify potential points of intervention and determine necessary data requirements to run the model. The article notes several limitations as well as recommendations for further improving the obesity system model. Experience from the workshop demonstrates the growing utility of systems thinking to approach complex public health problems and guide policymaking.

Individual Susceptibility to Dental Caries: The Vipeholm Study.

The evidence for a genetic component to dental caries is in comparison much less explored in the literature than the other classically described components of the disease: microbiota and diet. Diet can be said to have been conclusively linked to the etiology of dental caries by the results of the Vipeholm study, which did not deal with any microbial aspect of the disease. What is much less emphasized is that these same results provided one of the most robust lines of evidence that exist in support of a genetic component to dental caries. The results of the study showed great variability, with some study participants showing a dramatic increase in the establishment of new carious lesions under conditions that did not affect the majority of the other subjects. Similarly, highly cariogenic conditions due to a diet rich in sugars did not cause an increase in new carious lesions in other participants. The best explanation for these variable results is the existence of individual biological factors (genetic variation) modulating the disease. This chapter also comments on the ethical controversy surrounding the study and the need for finally intervening on the effects of sugars in oral health.

Multidimensional predictors of antidepressant responses: Integrating mitochondrial, genetic, metabolic and environmental factors with clinical outcomes

Major depressive disorder (MDD) is a primary psychiatric illness worldwide; there is a dearth of new mechanistic models for the development of better therapeutic strategies. Although we continue to discover individual biological factors, a major challenge is the identification of integrated, multidimensional traits underlying the complex heterogeneity of depression and treatment outcomes. Here, we set out to ascertain the emergence of the novel mitochondrial mediator of epigenetic function acetyl-L-carnitine (LAC) in relation to previously described individual predictors of antidepressant responses to the insulin-sensitizing agent pioglitazone. Herein, we report that i) subjects with MDD and shorter leukocyte telomere length (LTL) show decreased levels of LAC, increased BMI, and a history of specific types of childhood trauma; and that ii) these multidimensional factors spanning mitochondrial metabolism, cellular aging, metabolic function, and childhood trauma provide more detailed signatures to predict longitudinal changes in depression severity in response to pioglitazone than individual factors. The findings of multidimensional signatures involved in the pathophysiology of depression and their role in predicting treatment outcomes provide a starting point for the development of a mechanistic framework linking biological networks and environmental factors to clinical outcomes in pursuit of personalized medicine strategies to effectively treat MDD.

50 Long-term Motility of Semen Following Breeding Soundness Exams for Yearling Beef Bulls

Abstract To find an in vitro predictor of in vivoM/em&amp;gt; semen motility prompted this study. Our objective was to evaluate semen motility for an 8-hour period immediately following a breeding soundness exam. Ejaculates from 52 Angus and 56 Charolais bulls were evaluated. Motility, morphology, scrotal circumference and pH of ejaculate were evaluated at the time of collection. Ejaculates were then extended using a one to one ratio and incubated in a water bath held at 37 degrees Celsius and evaluated hourly. Motility was evaluated hourly for 8 hours, or until motility of the sample reached zero. Data were analyzed for breed and hourly effects using the GLIMMIX procedure of SAS. There was statistical evidence for difference (P &amp;lt; 0.0001) between breeds for motility over time. Angus ejaculates had higher pH values than Charolais ejaculates showing an association between breed and pH (6.82 vs 6.76, respectively). Primary spermatozoa abnormalities were greater (P &amp;lt; 0.0001) for Angus bulls compared to Charolais bulls (13.33% vs. 10.91%, respectively). Scrotal circumference between breeds tended to be different (P &amp;lt; 0.07), with Charolais bulls having a larger scrotal circumference compared to Angus bulls (38.29 vs. 38.03 centimeters, respectively). There was no difference (P &amp;gt; 0.05) between breeds for secondary abnormalities. There was a significant interaction (P &amp;lt; 0.01) between breed and time of motility measurement. Angus bull’s motility decreased drastically until hour 4, it then had a more gradual decrease until hour 8. Charolais bulls had a more gradual decrease in the percentage of motile sperm over time. In conclusion, there was evidence for difference between breeds for pH, primary spermatozoa abnormalities, and long-term motility, and a scrotal tendency. Understanding the effects of breed and individual biological factors may help producers adjust BSE expectations and lead to future research in long term semen motility.

Highly variable rate of orthodontic tooth movement measured by a novel 3D method correlates with gingival inflammation

ObjectivesIndividual orthodontic treatment duration is hard to predict. Individual biological factors are amongst factors influencing individual rate of orthodontically induced tooth movement (OTM). The study aim is to determine the rate of OTM by a novel 3D method and investigate parameters that may predict the rate of tooth movement.Materials and methodsIn this prospective cohort study, rate of OTM was determined from 90 three-dimensional intra-oral scans in 15 patients (aged 12–15) undergoing orthodontic treatment. For each patient, intra-oral scans were taken every week for up to 6 weeks (T0–T5). The teeth were segmented from the scans and the scans were superimposed on the palatal rugae. The rate of OTM was calculated for each tooth. Other parameters were gingival inflammation, contact-point displacement and the biological markers, matrix metalloproteinases (MMP), MMP-9 and MMP-2 in gingival crevicular fluid (GCF).ResultsOur study showed a high variation in the rate of OTM, varying from 0.15 to 1.24 mm/week. Teeth in the anterior segment tended to move more compared with the posterior segment. The contact point displacement and gingival inflammation varied greatly amongst the patients. The MMPs measured did not correlate with tooth movement. However, the gingival inflammation index showed a significant correlation with OTM. Future studies should include other biological markers related to bone-remodeling.ConclusionThis novel and efficient 3D method is suitable for measuring OTM and showed large individual variation in rate of OTM.Clinical relevancePatients show different rates of OTM. The rate of OTM in an individual patient can provide guidance in timing of follow-up appointments.

Quantification of water resource utilization efficiency as the main driver of plant diversity in the water-limited ecosystems

Identifying the drivers of species richness is a crucial for biodiversity conservation and community ecology. In this paper, the maximum utilization efficiency of water resources available to community is determined as the assembly law in an ecologically stable community with limited water resources. A plant community diversity model that incorporates water potential impedance is established, and the optimization model of community biodiversity structure was obtained based on water niche is also derived. It is shown that this optimization model can theoretically derive a species-area function similar to the traditional island biogeography curve, and it can also verify the predicted values of the species-area relationship experimentally and validated by long-term observations of plant diversity survey data. According to the model analyses, the total number of individuals (N) and the number of species (S) are determined by the combination of the water resources factors (the total quantity of available water resources in the growth season), the individual biological factors (the water consumption per unit mass of species in unit time), the complementary factors of inter- and intra-species water niche (the difference in water potential depending on the water use efficiency of the community), and plant community function factors (the total productivity of plant community). And as the area of plant communities increases, the heterogeneity of the water environment has increased. By adaptation and coevolution, more species are able to go through environmental and biological filtration, becoming community species that can utilize more available water resources at different spatial scales. Changes in water resources resulted in the community maximizing the utilization efficiency of water resources by adjusting the number and abundance of species. The main driving force for the increasing number of species is the full utilization of available water resources.

Associations of early-life growth with health using an allostatic load score in young, urban African adults: Birth to Twenty Plus Cohort.

Growth in early life is associated with various individual health outcomes in adulthood, but limited research has been done on associations with a more comprehensive measure of health. Combining information from multiple biological systems, allostatic load (AL) provides such a quantitative measure of overall physiological health. We used longitudinal data from the Birth to Twenty Plus cohort in South Africa to calculate an AL score at age 22 years and examined associations with birth weight and linear growth and weight gain from age 0 to 2 years and 2 to 5 years, as attenuated by trajectories of body mass index and pubertal development in later childhood and adolescence. Differences in total AL score between males and females were small, though levels of individual biological factors contributing to AL differed by sex. Increased weight gain from age 2 to 5 years among males was associated with an increased risk of high AL, but no other early-life measures were associated with AL. Increased adiposity through childhood and adolescence in females was associated with higher AL in early adulthood. These results illustrate that patterns of early-life growth are not consistently associated with higher AL. While more research is needed to link AL in young adulthood to later health outcomes, these results also suggest increased adiposity during childhood and adolescence represents a potential early sign of later physiological risk.

Biobehavioral Aspects of Health and Aging Among People of Mexican Origin

There is a growing interest in developing a deeper level of understanding of the complex phenomena that make up the aging process. Efforts to pursue questions using a multivariate and ecologically valid approaches that include biological and behavioral factors have led to significant advances in our knowledge. This special issue presents a collection of papers that represent this "biobehavioral" perspective. Little is known concerning the biobehavioral aspects of Hispanic health and there is a dearth of systematic study of how individual biological factors interact with the environmental and cultural factors to affect health outcomes among the swiftly growing older population of Mexican origin, a subgroup of older minorities that exhibits unique morbidity and mortality patterns. The group of papers here represents important contributions to understanding the health consequences in later life for individuals of Mexican descent and addresses several areas of interest including but not limited to diabetes, cognitive impairment, metabolic syndrome, frailty, socio-economic status and contextual factors that impact health. The papers presented here use interesting and useful transdisciplinary approaches that increase our knowledge of health processes in older people of Mexican descent. This special issue also provides excellent examples of the critical linkages between biological variables broadly defined and traditional social stratification, social inequalities, and social justice and the ways in which they interact. The papers taken together suggest that the processes involved in aging and health are complex, particularly in people of Mexican descent, and requires the understanding of mechanisms at multiple causes and levels of analysis.

Respiratory Effects of Opioids in Perioperative Medicine

Opioids are widely used to treat acute and chronic pain as well as respiratory distress. There is great variability in opioid-induced side effects due to individual biological factors, patient co-morbidities and drug interactions. Normal respiratory rhythm generation is decreased primarily via inhibititory effects within the pre-Bötzinger complex. Central chemosensitivity to hypercapnia and hypoxia are blunted by opioids at the levels of the retrotrapezoid nucleus, medullary raphe nucles and nucleus tractus solitarius. Opioids also decrease central drive to both respiratory pump muscles and the upper airway dilator muscles. Opioid-induced respiratory depression can be reversed by naloxone, and recent data suggest that 5-HT4(a) agonists and ampakines are effective to reverse some of the opioid-induced respiratory depressant effects. The potentially fatal side effects of respiratory depression within the acute peri-operative setting necessitates effective monitoring of respiratory function in all patients receiving opioid therapy. Each institution needs to develop an optimal organization structure locally to define appropriate methods for avoiding medication errors, titrating opioids to target effect, and monitoring for respiratory side effects.

Abstract 5475: Wnt pathway pharmacogenetics in lung cancer patients treated with platinum regimens

Abstract Background: The Wnt/β-catenin signaling is important in the development and progression of non-small cell lung cancer (NSCLC). Expression of Wnt pathway components was common in resected NSCLC and was associated with poor prognosis. Moreover, Wnt pathway expression in NSCLC cell lines correlated with increased cell growth and resistance to therapy. The host genotype may modulate the effect of individual biological factors on treatment and clinical outcome. Hence, we assessed Wnt pathway pharmacogenetics in patients with advanced NSCLC receiving platinum-based therapy. Method: Peripheral blood mononuclear cells (PBMCs) were collected from 598 inoperable stage III-IV NSCLC patients receiving platinum regimens. Genomic DNA was extracted from PBMCs and stored at -80o C. Illumina's Infinium iSelect HD Custom Genotyping BeadChip (Illumina, San Diego, CA) standard 3 day protocol was used to assess 441 host SNPs in 50 candidate Wnt pathway genes. BeadStudio software was used to autocall genotypes. SNPs with a call rate &amp;lt;95% were excluded from further analysis. Cox's proportional hazards model was used to estimate Hazard Ratios (HRs), with adjustment for age, sex, ethnicity, smoking status, clinical stage, performance status and therapy modality. The most common genotype served as the reference group. To correct for the effect of multiple comparisons, q values (a false discovery rate [FDR] adjusted P-value) were calculated by a method implemented in the R package. SNPs with q&amp;lt;0.10 were then used in the assessments of the combined effects of unfavorable genotypes. Survival tree analysis was performed to assess higher-order gene-gene interactions, Results: Survival correlated with 57 SNPs from 21 genes. After correcting for multiple comparisons, five SNPs remained significant in multivariate analysis, including the AXIN2 SNPs rs11868547 (Hazard Ratio [HR] for variant vs. reference SNP =0.77 [95% CI, 0.66-0.89], p=0.0006) and rs4541111 (HR=0.77 [0.68-0.91], p&amp;lt;0.002), as well as rs12819505 (Wnt-5B, HR=1.58 [1.19-2.09], p&amp;lt;0.002), rs4413407 (CXXC4, HR=1.28 [1.10-1.50], p&amp;lt;0.002), and rs10878232 (WIF-1, HR=1.36 [1.12-1.66], p&amp;lt;0.003). Cumulative analysis of these SNPs showed the joint effects of unfavorable genotypes on patient survival. Survival tree analysis based on four of these SNPs revealed higher order gene-gene interactions and classified patients into two groups of low and high death risk, with median survival time of 17.3 and 11.3 months respectively (log rank p&amp;lt; 5 × 10−8). Conclusions: Wnt pathway SNPs were significantly associated with survival of NSCLC patients treated with platinum-based chemotherapy. This supports published data suggesting that the Wnt pathway plays an important role in affecting clinical outcome for NSCLC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5475. doi:10.1158/1538-7445.AM2011-5475

A prospective study of the psychobehavioral factors responsible for a change from non-patient irritable bowel syndrome to IBS patient status

BackgroundTo investigate non-patient irritable bowel syndrome (IBS) change to IBS and to determine factors predictive of the onset of IBS, individual biological factors, psychological factors, behavioral factors, and environmental factors were examined.MethodsThe subjects were 105 non-patient IBS (male = 59, female = 46, average age:21.49 ± 2.37), including 68 of the diarrhea-predominant type and 37 of the constipation-predominant type selected from 1,409 university and technical college students by use of a questionnaire based on the Rome II diagnostic criteria. The subjects were followed for three years, and various characteristics and IBS symptoms were serially observed (12 times). The IBS incidence rate was calculated.ResultsDuring the three years, 37 non-patient IBS (35.24%) changed to IBS: 28 diarrhea-predominant type and 9 constipation-predominant type. All IBS symptoms disappeared in 26 non-patient IBS subjects (24.76%). According to quantification method II (discriminant analysis), seven factors (stressor, two kinds of stress coping styles, cognitive appraisal, eating habits, sleeping time, and psychologically abuse) were adopted as a predictive model for IBS incidence and were confirmed as predictive of IBS.ConclusionThe results of this research show that non-patient IBS is a changeable state that can change into IBS or persons without symptoms. Most of the non-patient IBS subjects who became asymptomatic had had symptoms for six months or less. Furthermore, the longer a non-patient IBS subject had symptoms, the higher the risk of a change to IBS became. The findings suggest the usefulness of identifying and approaching non-patient IBS as early as possible to prevent the onset of IBS. It must be noted that the persons surveyed in the present study had only the diarrhea-predominant and constipation-predominant types. Therefore, the findings of the present study are limited only these two types. Further study including the mixed type is needed.

Tuberculosis, Vulnerability, and Access to Quality Care

AS WITH MOST INFECTIOUS DISEASES TUBERCULOSIS (TB) is not randomly distributed; it thrives in specific groups and under specific conditions in association with identified and unidentified factors that confer vulnerability to the disease. Available information on the association between TB and the many known conditions and circumstances that influence vulnerability to the disease has been reviewed recently and is summarized in the BOX. These conditions and circumstances mainly include 3 broad categories of factors: individual biological factors (eg immunodeficiency states) social and economic circumstances (eg crowding poverty poor nutrition) and environmental and institutional factors (eg silica dust poor ventilation). (excerpt)

A method for evaluating the effects of biological factors on fish target strength

Abstract Understanding the relationship between fish biology and target strength potentially improves the accuracy of acoustic assessments. The effects of individual biological factors (e.g., length, tilt, and depth) on backscatter amplitude have been examined, but the relative contribution of each factor has not been quantified. Dimensionless ratios, which facilitate comparison of disparate quantities, were used to evaluate the effects of individual biological factors on echo intensities. Ratios from 25 adult walleye pollock (Theragra chalcogramma) were calculated using a Kirchhoff-ray-mode, backscatter model parameterized for each fish. This comparative approach can be used to identify the influence of biological factors on backscatter intensity and is potentially a tool for improving accuracy when converting acoustic size to fish length.

Complex analysis of lung cancer and stomach cancer risk factors

BACKGROUND: We conducted a multifactorial cancer epidemiology case-control study to assess effects of a complex of factors on high cancer morbidity of population of an industrial town in the central part of Russia. The study was carried out in the town of Tula, one of the oldest industrial centers of Russia with a high occupational and industrial load on the population and a high cancer incidence rate exceeding the Russian average rates by 38.4% in men and 89.9% in women. METHODS: We examined 200 lung cancer cases, 206 stomach cancer cases, and 213 controls, all residents of Tula. On each of the 619 study participants we collected personal data, which allowed characterization of cases and controls by a complex of 29 features reflecting well-known lung and stomach cancer risk factors. Mathematical processing was performed using the technique of multifactorial analysis based on mathematical pattern recognition methods. All tasks were solved in the package of applied programs of pattern recognition KVAZAR. RESULTS: The results of the multifactorial analysis of epidemiological data collected showed that the contribution of smoking in the development of stomach cancer in Tula was 7%, alcohol abuse 4%, occupational exposure to carcinogens 12% a complex of individual biological factors 28%, environmental factors 22% radiation factors 5%, nutrition habits 10%, and other factors 12%. The contribution of smoking in lung cancer mortality was 27%, alcohol abuse 4% occupational exposure to carcinogens 14%, a complex of individual biological factors 32%, environmental factors 9%, radiation factors 7%, and other factors 7%. CONCLUSION: The results of the epidemiological study carried out on the basis of methods of a multifactorial analysis in the city of Tula Russia, showed the effectiveness of such an approach to solving complicated epidemiological tasks. The suggested method allows one to assess a complex effect of different factors on oncologic morbidity in an industrial town and the prediction of effectiveness of various cancer preventive measures facilitates the choice of the most effective complex of preventive actions on the certain territory and at low cost.

Parenting and Family Support in Japan for 6- to 8-year-old Children Weighing under 1000 Grams at Birth

The purpose of this study was to explore the variables related to paternal involvement in the caregiving of 6- to 8-year-old extremely low-birthweight (ELBW) children, specifically, sociodemographic factors related to the family or individual biological factors related to ELBW. Thirty-three children with a mean birthweight of 845.5 grams and a mean gestational age of 27.4 weeks participated in this research. Approximately 29% of their fathers were classified by the mothers as nonco-operative in overall child care. The paternal involvement in caregiving was related to the sociodemographic variables of the family; the co-operative fathers were proportionally more often from families where the child had no older female sibling(s) and/or grandparent(s), whereas the nonco-operative fathers were proportionally more often from families where the child had older female sibling(s) and/or grandparent(s). The individual perinatal risk variables and IQ, and the paternal variables (age, socioeconomic status) were not related to the paternal co-operativeness. Our sample mothers seemed to have raised their children in more difficult parenting and economic situations, and to have received proportionally more support from grandparent(s) than did typical Japanese mothers. The children's relationships with peers differed between the paternal co-operative and nonco-operative groups; there were proportionally more children from the nonco-operative group who preferred to play alone than to play with peer(s) at the ages of 3-5 years. Thus, scarce paternal involvement in the process of caregiving appeared to influence the children's sociability.

The Influence of Individual Factors on the Absorption of Vibration Energy in the Hand and Arm

The detrimental effects of vibrating hand-held tools upon humans have been known for a long time, and determination of the absorption of vibration energy into the operator's hand and arm could be an alternative method of risk assessment. The energy absorption in the hand and arm during exposure to random vibration has been measured in 84 subjects. A special handle was used during the measurements. The influence of various experimental conditions, such as vibration level (3–12 m/s2), vibration direction (Xh, Yh, Zh), and grip force (25–75 N) as well as individual biological factors were studied. The results show that energy absorption is influenced by exposure directions and levels as well as grip forces. Furthermore, the results show that individual biological differences between subjects, for instance age, hand volume and hand thickness, have a significant influence on the amount of absorbed energy.

II. Representative view for the others

Identifying the drivers of species richness is a crucial for biodiversity conservation and community ecology. In this paper, the maximum utilization efficiency of water resources available to community is determined as the assembly law in an ecologically stable community with limited water resources. A plant community diversity model that incorporates water potential impedance is established, and the optimization model of community biodiversity structure was obtained based on water niche is also derived. It is shown that this optimization model can theoretically derive a species-area function similar to the traditional island biogeography curve, and it can also verify the predicted values of the species-area relationship experimentally and validated by long-term observations of plant diversity survey data. According to the model analyses, the total number of individuals (N) and the number of species (S) are determined by the combination of the water resources factors (the total quantity of available water resources in the growth season), the individual biological factors (the water consumption per unit mass of species in unit time), the complementary factors of inter- and intra-species water niche (the difference in water potential depending on the water use efficiency of the community), and plant community function factors (the total productivity of plant community). And as the area of plant communities increases, the heterogeneity of the water environment has increased. By adaptation and coevolution, more species are able to go through environmental and biological filtration, becoming community species that can utilize more available water resources at different spatial scales. Changes in water resources resulted in the community maximizing the utilization efficiency of water resources by adjusting the number and abundance of species. The main driving force for the increasing number of species is the full utilization of available water resources.