The pleiotropic effects of the glutamate dehydrogenase (GDH) pathway in Saccharomyces cerevisiae.

Ammonium assimilation is linked to fundamental cellular processes that include the synthesis of non-essential amino acids like glutamate and glutamine. In Saccharomyces cerevisiae glutamate can be synthesized from α-ketoglutarate and ammonium through the action of NADP-dependent glutamate dehydrogenases Gdh1 and Gdh3. Gdh1 and Gdh3 are evolutionarily adapted isoforms and cover the anabolic role of the GDH-pathway. Here, we review the role and function of the GDH pathway in glutamate metabolism and we discuss the additional contributions of the pathway in chromatin regulation, nitrogen catabolite repression, ROS-mediated apoptosis, iron deficiency and sphingolipid-dependent actin cytoskeleton modulation in S.cerevisiae. The pleiotropic effects of GDH pathway in yeast biology highlight the importance of glutamate homeostasis in vital cellular processes and reveal new features for conserved enzymes that were primarily characterized for their metabolic capacity. These newly described features constitute insights that can be utilized for challenges regarding genetic engineering of glutamate homeostasis and maintenance of redox balances, biosynthesis of important metabolites and production of organic substrates. We also conclude that the discussed  pleiotropic features intersect with basic metabolism and set a new background for further glutamate-dependent applied research of biotechnological interest.

Primary omental torsion in a 9 year old girl: a case report.

Primary torsion of the omentus is an extremely unusual cause of acute abdomen in the pediatric population. This condition occurs from twist of the pedicle of the omental apron around its longer axis, leading to edema, ischaemia and necrosis. Here we present a rare case of a 9 year old girl referred by her general practitioner due to severe right lower quadrant abdominal pain with a presumed diagnosis of acute appendiceal inflammation. Surgical operation disclosed primary omental torsion. The infarcted segment was resected and the girl's clinical recovery was uneventful without any complication. The condition may mimic a variety of other causes of acute abdominal symptoms. In this case report, a presumed diagnosis of acute appendicitis urgently induced the decision of a surgical approach. Physicians involved in the acute pediatric care have to include this rare condition in the differential diagnosis of acute onset right-sided abdominal pain.

Assessing children's diet quality in Crete based on Healthy Eating Index: the Children Study.

BACKGROUND: This study aimed to assess children's diet quality in Crete and the potential role of several socio-demographic factors related to it. METHODS: Between October 2005 and March 2006, 481 primary school children were recruited from Crete. Dietary intake data was obtained using a combination of techniques comprising a 24 h recall and 3 food diaries. The Healthy Eating Index (HEI) was calculated summing the individual scores (0-10) assigned to 10 index components. RESULTS: The majority of participants (84.5%) had diet that 'needs improvement' (HEI score: 51-80). Twelve percent of participants had 'poor diet' and only 3.5% of schoolchildren had 'good diet' (HEI score >80). The overall mean of the HEI score was 60.5. The mean values of the HEI components score ranged between 2.8 (that is, the HEI component that measures vegetables intake) and 9.9 (that is, component that expresses the variety of consumed foods). Low mean values were found in the total fat and saturated fat components (3.7 and 3.4, respectively). Moreover, the HEI score was strongly associated with dietary macronutrients and micronutrients intake. CONCLUSION: On the basis of the HEI score, the vast majority of children were found to have a diet that 'needs improvement'. This indicates the increased necessity of drawing and implementing nutrition education programs targeting both children and their families and aiming to increase vegetables and fruits intake and reduce fat intake.

Familial Mediterranean Fever in Crete: a genetic and structural biological approach in a population of 'intermediate risk'.

Familial Mediterranean Fever (FMF) is an autosomal, recessively inherited disease, characterized by recurrent and short attacks of fever with serosal inflammation that are caused by mutations in MEFV gene that encodes pyrin protein. To date, more than 70 disease-associated mutations have been identified, almost all of them representing missense nucleotide changes. FMF is very common among patients with Mediterranean ancestry, although the exact prevalence is not yet known, Greeks are considered to be at 'intermediate risk'. In the present study, we studied FMF patients in natives of Crete, a population sharing a common genetic and cultural background. The spectrum of MEFV gene mutations in 71 patients as well as 158 healthy controls was studied by performing a molecular analysis focused on the 12 most frequent FMF-associated mutations. We found that 59 of 71 (83.1%) FMF patients had at least one MEFV mutation, five patients were homozygotes and 54 heterozygotes for FMF-associated mutations. No mutations were detected in 12 patients (16.9%). As in high-risk populations, common MEFV mutations were found in Cretan FMF patients, with the M694V being the most penetrant. M694V and M694I mutations were associated with severe phenotypes, with many patients presenting with uncommon clinical manifestations such as erysipelas-like erythema or renal disturbances. Of interest, 20 (37%) of our heterozygous FMF patients presented with a severe phenotype. Population genetics analysis showed an FMF carrier frequency in healthy Cretan population of approximately 6% (1:17) and places Cretans closer to the Western rather than Eastern populations of the Mediterranean basin. Finally, we constructed a three-dimensional model showing the interaction of the PRYSPRY domain of pyrin with caspase-1 onto which we mapped MEFV mutations, classified according to disease severity. In this model, the 'flexible loops' of caspase-1 appear to have no access to some positions that have been previously associated with mild disease, suggesting that alternative pathogenic pathways leading to FMF need to be explored.

Prevalence and independent predictors of insulin resistance in children from Crete, Greece: the Children Study.

BACKGROUND: It has been proposed that insulin resistance (IR) is associated with the development of Type 2 diabetes mellitus and cardiovascular disease. The aim of this study is to determine the prevalence of IR in Greek schoolchildren and to investigate factors associated with IR. METHODS: Between October 2005 and March 2006, 522 children were recruited from Crete. Physical activity and dietary habits, anthropometric and biochemical characteristics, as well as medical history of pupils' parents were recorded. IR was estimated using the homeostasis model assessment (HOMA-IR), fasting glucose-to-insulin ratio (FGIR) and quantitative insulin sensitivity check index (QUICKI). Multiple linear regression was used to determine independent predictors for IR. RESULTS: Fasting insulin levels and HOMA-IR scores were higher in obese children and girls compared with their normal-weight peers (P < 0.001). Moreover, the former had lower values in FGIR and QUICKI indices compared with the latter, indicating that obese children and girls are more insulin resistant compared with their counterparts (P < 0.001). The prevalence of IR was 9.2% (2.9% in normal-weight, 10.5% in overweight and 31.0% in obese children), using as a threshold HOMA-IR > 2.10 97.5th percentile of normal-weight participants). Multiple linear regression revealed that central adiposity, female gender and intake of simple carbohydrates is associated positively with HOMA-IR values, even after controlling for many other factors. CONCLUSION: These findings demonstrate that girls and obese children, particularly those with central adiposity, are at high risk of developing IR. Therefore, these groups should be targets of Type 2 diabetes mellitus and cardiovascular disease preventive interventions.

The second cysteine-rich domain of Mac1p is a potent transactivator that modulates DNA binding efficiency and functionality of the protein.

Mac1p is a Saccharomyces cerevisiae DNA binding transcription factor that activates genes involved in copper uptake. A copper-induced N-C-terminal intramolecular interaction and copper-independent homodimerization affect its function. Here, we present a functional analysis of Mac1p deletion derivatives that attributes new roles to the second cysteine-rich (REPII) domain of the protein. This domain exhibits the copper-responsive potent transactivation function when assayed independently and, in the context of the entire protein, modulates the efficiency of Mac1p binding to DNA. The efficiency of binding to both copper-response promoter elements can determine the in vivo functionality of Mac1p independent of homodimerization.

The yeast Fre1p/Fre2p cupric reductases facilitate copper uptake and are regulated by the copper-modulated Mac1p activator.

Fre1p and Fre2p are ferric reductases which account for the total plasma membrane associated activity, a prerequisite for iron uptake, in Saccharomyces cerevisiae. The two genes are transcriptionally induced by iron depletion. In this communication, we provide evidence that Fre2p has also cupric reductase activity, as has been previously shown for Fre1p (Hassett, R., and Kosman, D.J. (1995) J. Biol. Chem. 270, 128-134). Both Fre1p and Fre2p enzymes are functionally significant for copper uptake, as monitored by the accumulation of the copper-regulated CUP1 and CTR1 mRNAs in fre1Delta, fre2Delta, and fre1Deltafre2Delta mutant strains. However, only Fre1p activity is induced by copper depletion, even in the presence of iron. This differential copper-dependent regulation of Fre1p and Fre2p is exerted at the transcriptional level of the two genes. We have shown that Mac1p, known to affect the basal levels of FRE1 gene expression (Jungmann, J., Reins, H.-A., Lee, J., Romeo, A., Hassett, R., Kosman, D., and Jentsch, S. (1993) EMBO J. 12, 5051-5056), accounts for both the copper-dependent induction of FRE1 and down-regulation of FRE2 gene. Finally, Mac1p transcriptional activation function is itself modulated by the availability of copper.