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Biomedical subjects

Apostolos G Vagenakis

Publications and source records attributed to Apostolos G Vagenakis.

At least 19 recordsLinked to original sources
PubMed2006

Thyroid hormone synthesis and secretion in humans after 80 milligrams of iodine for 15 days and subsequent withdrawal.

CONTEXT: In animals, acute iodine administration results in acute intrathyroidal inhibition of iodinations followed by escape of the inhibition if the excessive iodine intake continues. In humans, the intrathyroidal nonhormonal and hormonal iodine concentration after exposure to large doses of iodine for a relatively long period of time is not known. OBJECTIVE: To determine whether, in human thyroid, administration of large doses of iodine for a relatively long time results in alterations of intrathyroidal hormonal (HI) T4 and T3 and total iodine (TI) content, as well as whether changes in serum concentration of thyroid hormones and TSH would occur after iodine administration or discontinuation. DESIGN: In 33 euthyroid patients with single thyroid nodule or hyperparathyroidism, Lugol solution (80 mg iodine) was administered for 15 d before operation. Groups of six to eight patients underwent operation 0, 5, 10, and 15 d after iodine withdrawal. TI, HI in a sample of thyroid tissue, and serum concentration of T4, T3, and TSH were measured. In 21 normal euthyroid subjects who did not undergo operation, a similar protocol was used and serial blood measurements were taken. MAIN OUTCOME MEASURE: Intrathyroidal TI, HI, and serum thyroid hormone and TSH measurements were the main outcome measure. RESULTS: Intrathyroidal HI content and serum T4 and T3 were unchanged during and after iodine discontinuation. TI was increased during iodine administration and returned to control values 5 d after discontinuation of iodine. The ratio of HI/TI was decreased and returned to control values 15 d after the iodine was discontinued. Serum TSH was increased during iodine administration and returned to control values 10 d after iodine withdrawal. CONCLUSIONS: In humans, administration of iodine for a relatively long period of time was accompanied by increased intrathyroidal TI, but no changes in HI or demonstrable increases of serum T4 and T3 were observed. It is hypothesized that the maintenance of normal intrathyroidal HI is the result of the combined inhibitory effect of iodine on thyroid hormone synthesis and on the release of T4 and T3 from the thyroid.

Humans↗
PubMed2006

Adequacy of saliva 17-hydroxyprogesterone determination using various collection methods.

Steroids determination in saliva offers several advantages. The collection of saliva is a noninvasive, less stressful technique than blood withdrawal and reflects the circulating unbound fractions. The suitability of saliva for 17-hydroxyprogesterone and cortisol determinations has been documented in healthy subjects as well as in diseases like Congenital Adrenal Hyperplasia and Cushing syndrome. The aim of the study was to compare the influence of different collection methods on the results of 17-hydroxyprogesterone measurement in saliva collected by different ways, using commercially available RIAs developed for plasma. 17-hydroxyprogesterone was determined in 64 healthy adult volunteers (30 males, 34 females) in serum (Group SE) and in saliva collected before meals at 8-10 p.m. by directly spitting into a plastic tube (Group SP), using a cotton swab (Group SA) and using a polyester swab Salivette (Group SB). We used a commercially available direct radioimmunoassay without separation technique. The 17-hydroxyprogesterone mean values (ng/ml) were 1.16+/-1.3 (Group SE), 0.056+/-0.046 (Group SP), 0.089+/-0.048 (Group SA) and 0.058+/-0.049 (Group SB). The detection limit was 0.010 ng/ml. The correlations between the values in serum (Group SE) and in saliva were: r=0.77, p<0.05 (Group SP); r=0.62, p<0.05 (Group SA); r=0.70, p<0.05 (Group SB). The saliva values corresponding to the serum cut-off point of 3 ng/ml upper limit of normal values were in ng/ml 0.13 (Group SP), 0.16 (Group SA) and 0.11 (Group SB). In conclusion, 17-hydroxyprogesterone determinations in saliva using commercially available RIAs primarily developed for serum, is a reliable and easy to perform procedure. The three different methods of saliva collection showed 17-hydroxyprogesterone concentrations to have good agreement.

17-alpha-Hydroxyprogesterone↗
PubMed2006

Medical students' views of undergraduate Oncology education: A comparative study.

CONTEXT: An ongoing concern of undergraduate medical education regarding oncology has been intensified in Patras Medical School, Greece, aiming at a more comprehensive teaching approach. OBJECTIVE: A second-step research project was conducted to examine medical students' views of their undergraduate education in oncology, six years after the first investigation, and to assess the impact of the changes on the curriculum. METHODS: The same questionnaire used in the previous study was again distributed to 210 different medical students. FINDINGS: Our study revealed that although the quality of education in Oncology has been improved, it has not as yet reached high standards. The improvements over the last six years were mainly attributed to the increased presence of specialized oncology staff and their coordination with other basic and clinical scientists, as well as to the increased focus on research issues. Most of the students suggested putting more emphasis on psychosocial aspects of cancer care and ethical topics. DISCUSSION: Despite the progress made in the curriculum, there is still a need for further improvements in the students' undergraduate education so as to meet current demands. Medical education in Greece still pays lip service to communication and ethical issues while remaining disease-oriented in its approach. Therefore, the target of undergraduate education in Oncology should not only be the provision of updated medical knowledge, but also the development of a proper attitude towards all cancer-related issues.

Consumer Behavior↗
PubMed2006

Thyroid function in humans with morbid obesity.

Morbidly obese subjects may present with abnormal thyroid function tests but the reported data are scarce. Therefore, we studied the thyroid parameters in 144 morbidly obese patients, 110 females and 34 males, to assess the prevalence of hypothyroidism. Eleven percent (11.8%) carried the diagnosis of hypothyroidism and were undergoing levothyroxine (LT4) replacement therapy, 7.7% had newly diagnosed subclinical hypothyroidism, 0.7% had subclinical hyperthyroidism and 7.7% were euthyroid with positive antibodies (anti-thyroid peroxidase antibodies [TPOAb]). From the 144 subjects, we selected a cohort of 78 euthyroid subjects with negative TPOAb, who did not receive LT4 replacement or suppression therapy (the experimental group) and compared them to 77 normal-weight euthyroid subjects, TPOA-negative, matched for age and gender who served as controls. The experimental group had higher serum levels of triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), and thyrotropin (TSH) compared to the control group. Serum TSH concentration was associated with fasting serum insulin levels and insulin resistance but not with serum leptin levels, body mass index (BMI), fat mass, and lean body mass. In conclusion, in morbidly obese individuals, the prevalence of overt and subclinical hypothyroidism was high (19.5%). The morbidly obese subjects have higher levels of T3, FT3, T4, and TSH, probably the result of the reset of their central thyrostat at higher level.

Adult↗
PubMed2005

Statins and transcriptional regulation: the FXR connection.

Farnesoid X receptor (FXR) is a nuclear receptor involved in lipoprotein as well as glucose metabolism. Statins are widely used hypolipidemic agents with many pleiotropic actions. It is known that statins affect other nuclear hormone receptors, but no reports are available on the effect of these drugs on FXR. Employing an animal model (Syrian hamsters), we hereby present evidence to demonstrate that Simvastatin, a broadly prescribed statin, decreases the expression of FXR at both the RNA and protein levels and down-regulates its DNA-binding activity. This novel property may have important implications on the mode statins influence on lipoprotein and carbohydrate homeostasis in the organism.

Administration, Oral↗
PubMed2005

Delayed but normally progressed puberty is more pronounced in artistic compared with rhythmic elite gymnasts due to the intensity of training.

CONTEXT: Elite gymnasts are subjected to intense training, which may alter pubertal development. OBJECTIVE: The objective of the investigation was to study the impact of gymnastics on pubertal development in rhythmic (RGs) and artistic gymnasts (AGs). DESIGN: Evaluation of somatometric parameters, pubertal stage, and intensity of training in the competition field were studied. SETTING: The study was conducted at European and world championships of years 1997-2004. SUBJECTS: Subjects included 433 elite RGs and 427 AGs, aged 11-23 yr. INTERVENTION: There were no interventions. MAIN OUTCOME MEASURES: Mean chronological and bone ages of each pubertal stage and their relation to the intensity of training were measured. RESULTS: AGs and RGs showed a delay in skeletal maturation (Delta age-bone age, 2.13 and 1.28, respectively; P < 0.001). AGs were subjected to higher levels of physical training. Thelarche occurred at 12.9 yr for RGs and 13.2 yr for AGs (P = 0.003) and pubarche at 12.5 and 12.9 yr, respectively (P = 0.002). Puberty was delayed but normally progressed. AGs entered each pubertal stage later than RGs. The delay was influenced by the amount of energy output. Menarcheal age was 14.6 yr for RGs and 14.9 yr for AGs. Menarche was influenced in AGs by bone age (b = 0.333; t = 2.521; P = 0.020), pubarche (b = 0.322; t = 2.401; P = 0.026), and body fat (b = -0.458; t = -3.412; P = 0.003) and in RGs by bone age (b = 0.378; t = 3.689; P < 0.001) and pubarche (b = 0.525; t = 6.017; P < 0.001). CONCLUSION: In RGs and AGs, pubertal development was shifted to a later age, maintaining a normal rate of progression, which followed the bone age. AGs, who were exposed to a greater and more sustained energy output than RGs, presented a more pronounced delay in both skeletal maturation and pubertal development.

Adolescent↗
PubMed2004

Growth and skeletal maturation in male and female artistic gymnasts.

We studied 262 athletes who were 13-23 yr old. There were 93 male and 169 female artistic gymnasts (AG). This study is unique in character, because all variables were measured on the field of competition (24th European Championship). Male AG had a higher height SD score than female (P < 0.001), with a higher reported target height SD score (P < 0.001), a higher predicted final height (P = 0.007), a lower Delta height - target height (P < 0.001), a less delayed bone age (P < 0.001), a greater body mass index (BMI) (P < 0.001), a lower mean body fat (P<0.001), and an older age of onset of training (P < 0.001). In a subgroup of athletes who had reached final height, male AG had a higher weight SD score than female (t = 4.322, P < 0.001), with a higher reported target height SD score (t = 18.9, P<0.001), but a greater Delta final height-target height (t= 6.641, P < 0.001). Height SD score was positively correlated to reported target height SD score (P = 0.009 and P = 0.006, respectively) and to weight SD (P < 1 and P < 0.001, respectively) for both male and female AG, as well as to BMI for female AG (P<0.001), and negatively to Delta age - bone age (P < 0.001 and P = 0.003, respectively) and to predicted height SD score (P = 0.001 and P < 0.001, respectively). Using multiple regression analysis, height SD score was positively correlated to predicted height SD score for both male (P < 0.001) and female (P = 0.005) AG, as well as to weight SD score (P < 0.001) for female AG and negatively to BMI (P < 0.001) for female AG and to Delta age - bone age (P < 0.001) for male AG. In conclusion, a deterioration of growth in AG was observed. For both sexes, genetic predisposition to final height, although altered, was not disrupted.

Adolescent↗
PubMed2004

The influence of intensive physical exercise on bone acquisition in adolescent elite female and male artistic gymnasts.

Physical exercise enhances bone acquisition during adolescence. The aim of the study was to evaluate the influence of intensive physical exercise on bone acquisition in adolescent elite artistic gymnasts. The study included 262 athletes (93 males and 169 females, aged 13-23 yr) participating in the 24th European Championship held in Greece. Bone age compared with chronological age was delayed by 2 yr for females (n = 120) and 1 yr for males (n = 68). For both sexes, the growth chart of bone mineral density (BMD) followed a normal pattern when estimated according to bone age rather than chronological age. For females, BMD was positively correlated with bone age, chronological age, height, body weight, body mass index, body fat, lean body mass, and with age of onset of training, and negatively with duration of exercise and intensity of training (P values range from <0.05 to <0.0001). Multiple regression analysis revealed that age of onset of training was the major parameter attenuating the effect of exercise on BMD (P < 0.001). The latter was related to the stage of puberty (P < 0.05). For males, BMD was correlated positively with bone age, height, body weight, and lean body mass (P values range from <0.01 to 0.0001). Multiple regression analysis revealed that the more powerful factor influencing BMD was weight (P < 0.01). In conclusion, bone acquisition in adolescents under intensive physical training follows the normal pattern only when estimated according to bone age. The age of onset, the duration, and the intensity of exercise attenuate the bone acquisition, at least in female artistic gymnasts.

Adolescent↗
PubMed2004

Kallmann's syndrome and schizophrenia.

OBJECTIVE: Kallmann's Syndrome is a heritable disorder characterized by the association of hypogonadotropic hypogonadism and anosmia or hyposmia. A common pathogenesis for KS and schizophrenia had been proposed based on shared pathologies of these two disorders, although no such clinical associations have ever been reported. METHOD: We report a 35 year old man with schizophrenia and Kallmann's Syndrome. The patient presented with signs and symptoms of hypogonadism, severe hyposmia and normal endocrine functions of the anterior pituitary. Hyposmia has been attributed to the absence of the olfactory bulbs and tracts and atrophy of the olfactory gyri, but normal olfactory mucosa. The patient presented with paranoid schizophrenia with persecutory delusions, auditory hallucinations, thought disorder, depersonalization, and gradual but marked global deterioration. RESULTS: Psychiatric evaluation revealed an entirely different psychopathological and personality profile between the patient and the six other Kallmann patients studied. Cycle sequencing analysis revealed a normal sequence of all 14 exons of the KAL gene. In conclusion, based on the presented case, Kallmann's Syndrome and schizophrenia represent a rare clinical association rather than a syndrome with a common pathogenesis, which if present should be confined to the olfactory dysfunction.

Adult↗
PubMed2003

Functional significance of the thyrotropin receptor germline polymorphism D727E.

In a toxic thyroid adenoma we identified a novel somatic mutation that constitutively activates the thyrotropin receptor (TSHR). Two heterozygous point mutations at adjacent nucleotides led to a substitution of alanine with asparagine at codon 593 (A593N) in the fifth transmembrane helix of TSHR. This somatic mutation resided on the same TSHR allele with the germline polymorphism D727E. The functional characteristics of the single TSHR mutants A593N and D727E and of the double mutant A593N/D727E were studied in transiently transfected COS-7 cells. The TSHR mutants A593N and A593N/D727E constitutively activated the cAMP cascade, whereas the D727E mutant did not differ from the wild-type TSHR. Surprisingly, the double mutant's specific constitutive activity was 2.3-fold lower than the A593N mutant. Thus, the polymorphism significantly ameliorates G(alphas) protein activation in the presence of the gain-of-function mutation A593N, although it is functionally inert in the context of the wild-type TSHR.

Adenoma↗
PubMed2003

The alpha2B adrenergic receptor deletion/insertion polymorphism in morbid obesity.

The sympathetic nervous system participates in the regulation of the basal metabolic rate (BMR) and in the manifestation of the obesity-related metabolic syndrome. A deletion/insertion germline polymorphism of the alpha(2B) adrenergic receptor that is associated with reduced agonist-promoted desensitization has been linked to low BMR in obese subjects and to a predisposition to gain weight. This study investigated an association of the alpha(2B) polymorphism with the BMR and metabolic syndrome-related parameters of morbidly obese patients. Genotype frequencies were similar in patients and in a control group. The patients' BMR, adjusted for fat-free mass, fat mass, sex and age, did not differ between alpha(2B) genotypes. The polymorphism was also not associated with the patients' BMI, systolic and diastolic blood pressure, resting heart rate, total and HDL cholesterol, triglycerides, fasting glucose and uric acid levels. These findings do not support a major functional significance of the alpha(2B) adrenergic receptor polymorphism in the present sample of morbidly obese subjects.

Adolescent↗
PubMed2003

Effect of recombinant human erythropoietin on quality of life in cancer patients receiving chemotherapy: results of a randomized, controlled trial.

The purpose of this study was to assess whether the administration of recombinant human erythropoietin (rHuEPO) would correct anemia and improve the quality of life (QOL) in cancer patients receiving chemotherapy. One hundred twenty-two patients with hemoglobin </=11.0 g/dl were randomized to receive rHuEPO 10,000 U three times weekly (n = 61) or no additional treatment (n = 61). Response was assessed by measuring changes in hemoglobin level and QOL. QOL was evaluated before each cycle of chemotherapy at baseline, Week 4, and Week 12 using two separate self-report questionnaires. The analyses indicated that the rHuEPO-treated patients experienced significantly less fatigue (P < 0.05) than their control group counterparts, and reported significantly higher scores on energy level (P < 0.05), ability to perform daily activities (P < 0.01), and overall QOL (P< 0.05). The overall change in hemoglobin level was significantly greater in the rHuEPO group than in the control group (1.7 g/dl versus 0.3 g/dl, P < 0.001). rHuEPO effectively corrects anemia and significantly improves QOL in patients with solid tumors receiving chemotherapy.

Adult↗
PubMed2003

Prognostic significance of coronary artery calcium in asymptomatic subjects with usual cardiovascular risk.

BACKGROUND: Coronary calcium detected noninvasively is an attractive way to diagnose atherosclerosis before the development of symptoms. This study examines the prognostic value of coronary calcium in asymptomatic subjects with usual cardiovascular risk. METHODS AND RESULTS: In 425 asymptomatic subjects, 229 men (aged 45.1 +/- 14 years) and 196 women (aged 42.7 +/- 13 years), coronary calcium presence was studied by digital cinefluoroscopy. The majority (76%) had no or at most one risk factor. Subjects were followed up for 58.4 +/- 12.7 months for cardiac events. Coronary calcium was present in 76 of 425 (17.9%) subjects. Cardiac events were observed in 21 subjects: 2 cardiac deaths, 7 acute myocardial infarctions, 3 coronary artery bypass grafts, 3 coronary angioplasty procedures, 3 events of unstable angina, and 10 events of stable angina pectoris. Survival curve analysis showed significant differences in all the studied end points between subjects with and those without calcium. Coronary calcium was an independent predictor of all events (3.6-fold increase, P <.008), cardiac death/myocardial infarction/revascularization (13.9-fold increase, P <.02), and stable angina (7.4-fold increase, P <.007). However, calcium did not independently predict cardiac death/myocardial infarction or acute coronary syndromes. CONCLUSIONS: Coronary calcium in asymptomatic subjects with usual cardiovascular risk adds significant incremental information to risk factors information for the development of symptomatic coronary artery disease.

Adult↗
PubMed2003

Hyperthyrotropinemia during iodide administration in normal children and in children born with neonatal transient hypothyroidism.

The aim of the present study was to examine the effects of chronic iodide administration in pharmacological doses on thyroid function in children with a history of transient congenital hypothyroidism (TCH). We hypothesized that such children may carry a previously undisclosed intrinsic intrathyroidal defect, rendering them susceptible to TCH. We administered for this 60-65 mg iodide daily for 60 d in 13 individuals with TCH (group A), 8 of their siblings (group B), 8 healthy controls (group C), and 11 normal adults (group D). Thyroid function was evaluated by measuring serum T(3), T(4), free T(3), free T(4), TSH, and thyroglobulin concentrations and autoantibodies against thyroid peroxidase and thyroglobulin at baseline at 15, 30, and 60 d during iodide administration, and 2 months after iodide withdrawal. Hyperthyrotropinemia greater than 4.2 mU/liter but not higher than 10 mU/liter with normal thyroid hormone concentrations was observed in one of the TCH group and in two of the group B siblings. During iodide administration, hyperthyrotropinemia was observed in 8 of 13 (62%) adolescents in group A, 4 of 7 (57%) in group B, and 6 of 8 (75%) in group C. None of the 11 adults (group D) developed hyperthyrotropinemia during iodide administration. Serum T(4) and free T(4) concentrations were decreased in all groups when compared with baseline values. The magnitude of the decrease of serum T(4) was identical in all groups (0.7-0.8 microg/dl). Thyroid enlargement was observed in all subjects and was more pronounced in children. There were no cases of subclinical and/or overt hyperthyroidism. After iodine withdrawal, serum TSH decreased in all groups and returned to baseline levels, as well as the thyroid volume. In conclusion, the hypothalamic-pituitary-thyroid axis of adolescents with TCH responds to pharmacological doses of iodide similarly to that observed in normal children. The hyperthyrotropinemia observed in the adolescents exposed to iodides may reflect incipient transient hypothyroidism or simply a brisk TSH response to a small serum T(4) decrease. Whatever the mechanism, chronic use of excessive quantities of iodide should be avoided until the end of puberty.

Adolescent↗
PubMed2003

Autonomously functioning thyroid nodules in a former iodine-deficient area commonly harbor gain-of-function mutations in the thyrotropin signaling pathway.

BACKGROUND: Somatic activating mutations of the thyrotropin (thyroid-stimulating hormone (TSH)) receptor (TSHR) and G(alphas) protein have been detected in solitary toxic adenomas and toxic multinodular goiters, but their role in the pathogenesis of autonomous nodules is debated. The frequency of mutations is highly variable among populations and is inversely proportional to iodine intake. DESIGN AND PATIENTS: We screened 28 clinically and histologically heterogeneous autonomous nodules from 24 Greek patients for the presence of TSHR and G(alphas) mutations. RESULTS: By direct sequencing of genomic DNA, we detected 11 somatic heterozygous gain-of-function mutations in TSHR and one in G(alphas). Forty-three percent (12 of 28) of all nodules and 57% (four of seven) of solitary toxic adenomas harbored an activating mutation. Typical adenomas and hyperplastic nodules did not differ in mutation frequency. Substitutions I568T and T632I were detected in both histological types of nodules. CONCLUSIONS: Our findings indicate that activating somatic mutations in the TSH signaling pathway are frequent in autonomous nodules in Greece. This may be due to earlier exposure of the population to iodine deficiency, which was corrected in Greece only over the past two decades. Gain-of-function mutations are shared by nodules with varying histological and clinical presentations. Thus, they may represent a common molecular mechanism underlying the pathogenesis of non-autoimmune thyroid autonomy.

Adenoma↗
PubMed2003

Restoration of euglycemia and normal acute insulin response to glucose in obese subjects with type 2 diabetes following bariatric surgery.

Insulin resistance and loss of glucose-stimulated acute insulin response (AIR) are the two major and earliest defects in the course of type 2 diabetes. We investigated whether weight loss after bariatric surgery in patients with morbid obesity and type 2 diabetes could restore euglycemia and normal AIR to an intravenous glucose tolerance test (IVGTT). We studied 25 morbidly obese patients-12 with type 2 diabetes, 5 with impaired glucose tolerance, and 8 with normal glucose tolerance (NGT)-before and after a biliopancreatic diversion (BPD) with Roux-en-Y gastric bypass (RYGBP). Twelve individuals with normal BMI served as control subjects. Twelve months after surgery, in the diabetes group, BMI decreased from 53.2 +/- 2.0 to 29.2 +/- 1.7 kg/m(2), fasting glucose decreased from 9.5 +/- 0.83 to 4.5 +/- 0.13 mmol/l, and fasting insulin decreased from 168.4 +/- 25.9 to 37.7 +/- 4.4 pmol/l (mean +/- SE; P < 0.001). AIR, the mean of insulin concentration at 2, 3, and 5 min over basal in the IVGTT, increased by 770 and 935% at 3 and 12 months after surgery, respectively (from 24.0 +/- 22.7 to 209 +/- 43.4 and 248 +/- 33.1 pmol/l, respectively; P < 0,001). Conversely, in the NGT group, the AIR decreased by 40.5% (from 660 +/- 60 to 393 +/- 93 pmol/l; P = 0.027) 12 months after surgery. BPD with RYGBP performed in morbidly obese patients with type 2 diabetes leads to significant weight loss, euglycemia, and normal insulin sensitivity; but most importantly, it restores a normal beta-cell AIR to glucose and a normal relationship of AIR to insulin sensitivity. This is the first study to demonstrate that the lost glucose-induced AIR in patients with type 2 diabetes of mild or moderate severity is a reversible abnormality.

Adult↗