Biomedical subjects

Christos Hatzis

Publications and source records attributed to Christos Hatzis.

6 recordsLinked to original sources

PubMed2006

Depression and serum adiponectin and adipose omega-3 and omega-6 fatty acids in adolescents.

The purpose of the present study was to investigate for a possible relationship between depression and serum adiponectin and adipose tissue omega-3 and omega-6 PUFA. The sample consisted of 90 healthy adolescent volunteers from the island of Crete. There were 54 girls and 36 boys, aged 13 to 18. The mean age was 15.2 years. Subjects were examined by the Preventive Medicine and Nutrition Clinic of the University of Crete. Depression was assessed through the use of the Beck Depression Inventory (BDI) and the Center for Epidemiologic Studies Depression Scale (CES-D). Fatty acids were determined by gas chromatography in adipose tissue. CES-D correlated with dihomo-gamma linolenic acid (DGLA). Multiple linear regression analyses showed that BDI was negatively associated with eicosapentaenoic acid (EPA), while CES-D was positively associated with DGLA in adipose tissue. Serum adiponectin was not significantly associated with depression. The negative relationship between adipose EPA and depression in adolescents, is in line with findings of previous studies involving adult and elderly subjects, demonstrating negative relations between depression and adipose omega-3 PUFA. This is the first literature report of a relationship between depression and an individual omega-3 fatty acid in adolescents. The inverse relationship between adipose EPA and depression indicates that a low long-term dietary intake of EPA is associated with an increased risk for depression in adolescents.

Adiponectin↗

PubMed2006

Towards understanding of the complex structure of growing yeast populations.

In a growing Saccharomyces cerevisiae population, cell size is finely modulated according to both the chronological and genealogical ages. This generates the complex heterogeneous structure typical of budding yeast populations. In recent years, there has been a growing interest in developing mathematical models capable of faithfully describing population dynamics at the single cell level. A multistaged morphologically structured model has been lately proposed based on the population balance theory. The model was able to describe the dynamics of the generation of a heterogeneous growing yeast population starting from a sub-population of daughter unbudded cells. In this work, which aims at validating the model, the simulated experiment was performed by following the release of a homogeneous population of daughter unbudded cells. A biparametric flow cytometric approach allowed us to analyse the time course joint distribution of DNA and protein contents at the single cell level; this gave insights into the coupling between growth and cell cycle progression that generated the final population structure. The comparison between experimental and simulated size distributions revealed a strong agreement for some unexpected features as well. Therefore, the model can be considered as validated and extendable to more complex situations.

Cell Cycle↗

PubMed2006

Ambient particulate matter exhibits direct inhibitory effects on oxidative stress enzymes.

A primary mechanistic hypothesis by which ambient air particles have a significant negative impact on human health is via the induction of pulmonary inflammatory responses mediated through the generation of reactive oxygen species (ROS). Development of a biosensor for the assessment of particulate ROS activity would be a significant advance in air pollution monitoring. The objective of this study was to evaluate whether air particulates interact directly with protective enzymes involved in oxidative stress responses. We performed enzyme activity assays on four enzymes involved in oxidative stress responses (Cu/Zn superoxide dismutase, Mn superoxide dismutase, glutathione peroxidase, and glutathione reductase) in the presence of particles of varying toxicities and found distinctive inhibition patterns. On the basis of these findings, we suggest a strategy for an enzyme bioassay that could be used to assess the potential of particles to generate ROS-induced responses.

Air Pollutants↗

PubMed2006

Morphologically-structured models of growing budding yeast populations.

It has been well recognized that many key aspects of cell cycle regulation are encoded into the size distributions of growing budding yeast populations due to the tight coupling between cell growth and cell division present in this organism. Several attempts have been made to model the cell size distribution of growing yeast populations in order to obtain insight on the underlying control mechanisms, but most were based on the age structure of asymmetrically dividing populations. Here we propose a new framework that couples a morphologically-structured representation of the population with population balance theory to formulate a dynamic model for the size distribution of growing yeast populations. An advantage of the presented framework is that it allows derivation of simpler models that are directly identifiable from experiments. We show how such models can be derived from the general framework and demonstrate their utility in analyzing yeast population data. Finally, by employing a recently proposed numerical scheme, we proceed to integrate numerically the full distributed model to provide predictions of dynamics of the cell size structure of growing yeast populations.

Cell Cycle↗

PubMed2004

Association of adipose tissue arachidonic acid content with BMI and overweight status in children from Cyprus and Crete.

The relationships between n-3 and n-6 fatty acids in subcutaneous fat, BMI and overweight status were investigated in eighty-eight children from Crete and Cyprus. Overweight status, BMI and serum lipid levels were similar in children at both locations, but Cretan children had higher levels of total MUFA than Cypriot children (62.2 (sd 2.8) v. 52.2 (sd 2.8) % area, respectively, P<0.001) and consequently Cypriot children had higher levels of total saturated, polyunsaturated, trans, n-3 and n-6 fatty acids. Cypriot children had also higher levels of individual n-3 and n-6 fatty acids, specifically linoleic, alpha-linolenic and dihomo-gamma-linolenic acids. The variance of BMI was better explained (38.2 %) by adipose tissue arachidonic acid content than any other n-3 and n-6 fatty acids. Mean levels of arachidonic acid, dihomo-gamma-linolenic acid and docosahexaenoic acid were higher in overweight and obese subjects. All obese subjects fell in the 4th quartile of arachidonic acid levels, whereas 88.9 % of overweight subjects fell in the 3rd and 4th quartile of arachidonic acid. These results indicate positive associations between adipose tissue arachidonic acid and BMI and overweight status. Further research could clarify whether this association is causal.

Adipose Tissue↗

PubMed2002

Health and nutrition education in primary schools of Crete: changes in chronic disease risk factors following a 6-year intervention programme.

The effectiveness of a health and nutrition education programme, in changing certain chronic disease risk factors, was assessed after the 6 years intervention period was completed. The school-based intervention programme was applied to all children registered in the first grade (age 5.5-6.5 years) in 1992 in two counties of Crete, while the children from a third county served as a control group. In order to assess the effectiveness of the intervention, a variety of biological and behavioural parameters were measured before and following completion of the intervention in a randomly selected school-based sample of 602 intervention group (IG) and 444 control group (CG) pupils. At the end of the 6-year period, it was found that biochemical indices generally improved significantly more in the IG compared with the CG (mean change for IG v. CG was -0.27 v. -0.12 mmol/l for total cholesterol (TC); -0.07 v. +0.24 for TC:HDL and -0.13 v. +0.14 for LDL:HDL). Similarly, the changes observed in the anthropometric variables in the two groups were in favour of the IG (+3.68 v. +4.28 kg/m2 for BMI; +2.97 v. +4.47 mm for biceps skinfold). Total energy intake and consumption of total fat and saturated fat increased significantly less in the IG compared with the CG (+747.7 v. 1534.7 kJ (+178.7 v. +366.8 kcal); +5.9 v. +18.8 g and +0.8 v. +5.1 g respectively), while time devoted to leisure time physical activity and cardiovascular run test performance increased significantly more in the IG (+281 v. +174 min/week and +2.5 v. +1.2 stages respectively). The findings of the present study underline the importance of such programmes in health promotion and disease prevention. Although the long-term effects of these programmes can only be assessed by tracking this population through to adolescence and adulthood, these programmes seem to have the potential to lead to a healthier lifestyle and thus a reduction in risk factor levels.

Anthropometry↗