Biomedical subjects

A Petri

Publications and source records attributed to A Petri.

At least 19 recordsLinked to original sources

PubMed2006

Brownian forces in sheared granular matter.

We present results from a series of experiments on a granular medium sheared in a Couette geometry and show that their statistical properties can be computed in a quantitative way from the assumption that the resultant from the set of forces acting in the system performs a Brownian motion. The same assumption has been utilized, with success, to describe other phenomena, such as the Barkhausen effect in ferromagnets, and so the scheme suggests itself as a more general description of a wider class of driven instabilities.

Journal Article↗

PubMed2006

Ghrelin secretion in preterm neonates progressively increases and is refractory to the inhibitory effect of food intake.

CONTEXT: Ghrelin, a natural GH secretagogue, is mainly characterized by nonendocrine activities such as orexigenic effect and modulation of the endocrine and metabolic response to variations in energy balance. Ghrelin levels have been reported to be negatively associated with insulin secretion, enhanced in anorexia, and reduced in obesity. Ghrelin levels in newborns were shown to be similar to those found in children and adults without any gender-related difference. OBJECTIVE: The aim of this study was to evaluate ghrelin variations in preterm newborns as a function of fasting and feeding. METHODS: To this end, in 31 preterm neonates (13 males and 18 females) categorized as appropriate for gestational age, total ghrelin levels were measured in cord blood and then on the fourth day of life before and after meals. RESULTS: Ghrelin levels in cord blood [(median 25th-75th centile) 184; 122-275 pg/ml] were higher (P < 0.006) than levels measured in the mothers at delivery (167.0; 89-190 pg/ml). In newborns on the fourth day of life, ghrelin levels in fasting conditions (451; 348-649 pg/ml) were higher (P < 0.0004) than those in cord blood. The meal did not at all modify ghrelin levels (476; 302-775 pg/ml), which were unchanged, compared with those in fasting condition. Total ghrelin levels in cord blood were not associated with weight and length; conversely, on the fourth day of life ghrelin levels in newborns were negatively correlated to birth weight as well as the present weight (P = 0.05, r = -0.4). Ghrelin levels were independent of gender, type of delivery, and the kind of feeding regimen. CONCLUSIONS: The secretion of total ghrelin increases from delivery to the fourth day of life when it is refractory to the inhibitory effect of food intake, but it is negatively correlated to body weight.

Body Height↗

PubMed2006

Response of male BUT big 6 turkeys to varying amino acid feeding programs.

Dietary protein is a major cost contributor in turkey nutrition. Therefore, a feeding trial with male BUT Big 6 turkeys to 154 d of age was conducted to examine how live performance and economics are affected when dietary amino acid levels are altered in different phases. Six dietary treatments were run with treatment 1 as the control in which balanced protein levels were according to recommendations during all 6 phases. Treatments 2 through 6 used combinations of balanced protein (based on lysine) that ranged from 90 to 120% of those used in treatment 1. The combinations for the 6 phases of feeding were 120, 120, 120, 120, 90, and 90% for treatment 2; 120, 120, 120, 100, 90, and 90% for treatment 3; 120, 120, 100, 100, 90, and 90% for treatment 4; 120, 120, 120, 120, 100, and 100% for treatment 5; and 90, 90, 90, 100, 100, and 100 for treatment 6. Final BW was highest in treatment 4 and lowest in treatment 2 (P < 0.05), whereas final BW were intermediate and statistically not different in treatments 1, 3, 5, and 6. Breast meat yield was highest in treatment 5 and lowest in treatments 2 and 3 (P < 0.05). Mortality seemed to be reduced in treatment 6 compared with treatments 2, 3, and 5 (P < 0.10). Performance data in combination with economic simulations suggested that the feeding regimens of treatments 4 or 6 might be alternative strategies to treatment 1 to improve overall profitability.

Amino Acids↗

PubMed2006

Responses of male growing broilers to increasing levels of balanced protein offered as coarse mash or pellets of varying quality.

Two experiments with 14- to 35-d-old male broilers were performed to investigate the interactions between increasing levels of balanced protein (BP; 9.7, 10.7, 11.7, and 12.7 g of digestible Lys/kg of feed) and physical feed form. In Experiment 1 diets were offered as coarse mash and pellets of either good or poor quality. Good pellet quality was characterized by high durability. In Experiment 2 diets were offered as good quality pellets or coarse mash. However, for the latter particle size, distribution either was kept constant with increasing BP or changed with increasing proportion of soybean meal. Feed intake generally decreased with increasing BP; however, feed intake was highest in good pellets fed to broilers and lowest in mash fed to birds. Although there was only a small response on weight gain in mash-fed birds, feed conversion improved substantially for all feed forms with increasing BP. Particle size distribution did not affect this effect. Highest weight gain was achieved with good pellets; to achieve similar performance with poor pellet quality, higher levels of BP were needed. Carcass evaluation suggested increasing breast meat yield and particularly decreasing fat accretion with increasing BP. Results of both experiments indicate that optimum dietary amino acid levels for growing broilers may vary among different physical feed forms.

Animal Feed↗

PubMed2006

Oral glucose load inhibits circulating ghrelin levels to the same extent in normal and obese children.

OBJECTIVE: The presence of both the GH secretagogue (GHS) receptor and ghrelin in the pancreas indicates an involvement of this hormone in glucose metabolism. Ghrelin secretion is increased by fasting and energy restriction, decreased by food intake, glucose load, insulin and somatostatin in normal adults; however, food intake is not able to inhibit circulating ghrelin levels in children, suggesting that the profile of ghrelin secretion in children is different from that in adults. Moreover, how ghrelin secretion is regulated in childhood as a function of fat mass is still unclear. DESIGN AND SUBJECTS: We studied the effect of oral glucose load (75 g solution orally) on circulating total ghrelin levels in 14 obese children (group A, four boys and 10 girls, aged 9.3 +/- 2.3 years) and 10 lean children (group B, five boys and five girls, aged 9.7 +/- 3.8 years). MEASUREMENTS: In all the sessions, blood samples were collected every 30 min from 0 up to +120 min. GH, insulin and glucose levels were assayed at each time point. RESULTS: Glucose peaks following an oral glucose tolerance test (OGTT) in groups A and B were similar; however, both basal and OGTT-stimulated insulin levels in group A were higher than in group B (P < 0.05). Basal total ghrelin levels in group A (281.3 +/- 29.5 pg/ml) were lower (P < 0.0005) than in group B (563.4 +/- 81.5 pg/ml). In both groups A and B, the OGTT inhibited total ghrelin levels (P < 0.005). In terms of absolute values, total ghrelin levels in group A were lower (P < 0.0005) than those in group B at each time point after glucose load. The percentage nadir in total ghrelin levels recorded in group A (-25% at 90 min) was similar to that recorded in group B (-31% at 120 min). Total ghrelin levels were negatively associated with BMI (r = 0.5, P < 0.005) but not with glucose or insulin levels. CONCLUSION: Ghrelin secretion is reduced in obese children. It is, however, equally sensitive in both obese and lean children to the inhibitory effect of oral glucose load.

Administration, Oral↗

PubMed2006

Role of ghrelin in the regulation of appetite in children.

Ghrelin, the new recently discovered hormone, is a 28 amino-acid acylated peptide predominantly produced by the stomach characterized by a strong GH-releasing activity mediated by the hypothalamic-pituitary GH secretagogues (GHSs) receptors. Ghrelin and GHSs, acting on central and peripheral receptors, exert other actions such as stimulation of ACTH and prolactin secretion, influence on insulin secretion and glucose metabolism, orexigenic effect and modulatory activity on the neuroendocrine and metabolic response to starvation, influence on exocrine gastro-entero-pancreatic functions, cardiovascular activities and modulation of cell proliferation and apoptosis. The wide spectrum of ghrelin action requires further studies to provide critical information on the role of ghrelin and the potential perspectives of its analogues in the clinical practice. This point is of particular interest in the field of pediatric endocrinology and metabolism because the ghrelin story started focusing on GH deficiency and is now extending to aspects that once again are of major relevance such as obesity and eating disorders, regulation of the hypothalamus-pituitary-adrenal and gonadal axis. More studies are needed to evaluate the real impact of ghrelin in different non endocrine processes and the possible use of ghrelin analogues in different diseases condition.

Appetite↗

PubMed2005

Shear stress fluctuations in the granular liquid and solid phases.

We report on experimentally observed shear stress fluctuations in both granular solid and fluid states, showing that they are non-Gaussian at low shear rates, reflecting the predominance of correlated structures (force chains) in the solidlike phase, which also exhibit finite rigidity to shear. Peaks in the rigidity and the stress distribution's skewness indicate that a change to the force-bearing mechanism occurs at the transition to fluid behavior, which, it is shown, can be predicted from the behavior of the stress at lower shear rates. In the fluid state stress is Gaussian distributed, suggesting that the central limit theorem holds. The fiber bundle model with random load sharing effectively reproduces the stress distribution at the yield point and also exhibits the exponential stress distribution anticipated from extant work on stress propagation in granular materials.

Journal Article↗

PubMed2005

Increased liver enzymes and hormonal therapies in girls and adolescents with Turner syndrome.

Elevated liver enzymes can be seen relatively frequently in patients with Turner syndrome (TS), while the pathogenesis of this remains unclear. Our epidemiological and prospective study aimed to investigate: a) the natural 2-yr course of liver disease in a selected cohort of young patients with TS, who had been preliminarily recruited on the basis of persistently elevated liver enzymes; b) the role of prolonged hormonal therapies in the etiology of liver dysfunction. From an overall population of 214 TS patients younger than 20 yr, only 19 (8.9%) were recruited, according to the following inclusion criteria: increased serum concentrations of one or more liver enzymes, exceeding the uppermost limit of the respective normal ranges, and persistence of these liver alterations for 6 months after the preliminary assessment. On the basis of the results of this prospective study, we can conclude that: a) the prevalence of liver abnormalities in girls and adolescents with TS is much lower and more strictly related to hormonal therapies than in TS adults; b) both autoimmunity and obesity are not frequently involved in the etiology of TS liver dysfunction; c) liver damage is either mild or moderate and its severity is not conditioned by karyotype; d) its course may be self-limiting; e) its natural history may be characterized in some cases by a slight deterioration of intrahepatic cholestasis, with no negative repercussions on liver synthetic function.

Adolescent↗

PubMed2005

Routine database registration of biological therapy increases the reporting of adverse events twentyfold in clinical practice. First results from the Danish Database (DANBIO).

OBJECTIVE: To present from the Danish Database for Biological Therapies in Rheumatology (DANBIO) the frequencies and types of adverse events as well as risk factors during treatment with biological agents in clinical practice. METHODS: Adverse events during the first 2 years of clinical use of biological agents in Denmark were reported to the nationwide DANBIO and compared to the mandatory reports to the Danish Medicines Agency. RESULTS: Almost 90% of the patients treated with biological agents were registered in the DANBIO, and the database picked up 20 times as many adverse events as the Danish Medicines Agency. Infections and hypersensitivity reactions were the most prevalent adverse events. Age, disease duration, and previous number of disease-modifying anti-rheumatic drugs (DMARDS) were found to be risk factors for bacterial infections. CONCLUSION: A routine-based Danish database for biological therapies covers approximately 90% of patients and improves the reporting of adverse events.

Adult↗

PubMed2004

Particle size investigations of a multistep synthesis of PVA coated superparamagnetic nanoparticles.

Nanoscaled particles showing superparamagnetic behavior have been intensively studied in the past years for various applications. Nevertheless, the lack of well-defined particles remains an important problem. One of the major challenges is still the large-scale synthesis of particles with a narrow size distribution. The aim of this work is to synthesize and characterize ferrofluids throughout a multistep synthesis. The iron oxide nanoparticles are first obtained by classical coprecipitation in water, followed by a thermochemical treatment and centrifugation to obtain well-dispersed primary nanoparticles. Finally polyvinyl alcohol is grafted onto the particles to ensure colloidal stability of the ferrofluid at neutral pH. The different synthesis steps and intermediate and side products are described. A model is proposed for the stabilization mechanism.

Journal Article↗

PubMed2004

Leptin levels as function of age, gender, auxological and hormonal parameters in 202 healthy neonates at birth and during the first month of life.

Leptin signals to the brain energy stores and balance while integrating neuroendocrine functions. Leptin levels in adults are higher in females than in males, while a gender-related difference in newborns is controversial. To clarify this point, in 202 healthy neonates we measured dynamic changes in leptin levels over the first month of life and looked for correlation between leptin levels and auxological and hormonal parameters. Cord leptin concentration in females was higher (p < 0.001) than in males. IGF-I, IGF-II, insulin, testosterone and 17beta-estradiol levels were similar in both sexes while insulin-like growth factor binding protein 3 (IGF-BP3) levels in females were slightly higher than in males. Leptin levels were positively associated to body weight, gestational age, IGF-BP3 levels, insulin levels and maternal body mass index (BMI) at time of delivery. In a subset of subjects (no. = 65), in comparison with cord levels, serum leptin levels were decreased on the 5th day of life (p < 0.0001) and then increased at 1 month (p < 0.0001). Positive association between leptin and weight was lost on the 5th day of life but present again at 1 month. In conclusion, our findings in a large population of neonates definitely show that leptin levels at birth are functions of gender, body weight and gestational age but not of length, cranial circumference, IGF-I and IGF-II levels. These findings, coupled with weight-independent prompt decrease after birth followed by weight-dependent increase at one month of life, suggest that leptin secretion in neonates as well as in adults mainly signals the nutritional state to the brain.

Adult↗

PubMed2004

[Surgical treatment of acquired, benign esophago-respiratory fistulas].

BACKGROUND: Acquired, benign esophago-respiratory fistula occurs as a rare complication of different disorders. STUDY DESIGN: Over a period of 30 years, 37 patients with acquired, benign esophago-respiratory fistulas were treated at the authors' institutions. 35 of the 37 patients were operated upon. Acute operation involved primary repair of the trachea and esophagus, or intubation of the gullet and/or gastrostomy. Elective operations were performed on 13 patients. RESULTS: Complications were observed in 14 patients. There were 4 cases with anastomotic leakage (all of them on the neck). Direct closure was carried out in 2 patients; the remaining 2 cases healed spontaneously. None of the 4 patients died. Seven of the 37 patients died (18.9%). This seems acceptable in view of the severity of the cases and the extension of the operations. CONCLUSIONS: 1. The causes of a majority of the esophago-respiratory fistulas in this material are connected with the complications of corrosive injury and peptic stricture of the esophagus. 2. The well-known fact that most of these fistulas occur in the right chest is confirmed. 3. Gastrostomy and/or intubation of the gullet seems to be the best solution for this lesion in the acute cases and in severely ill patients. 4. In elective cases, reconstruction is suggested, if possible in one step.

Adult↗

PubMed2004

Plasma TNF binding capacity profiles during treatment with etanercept in rheumatoid arthritis.

BACKGROUND: Etanercept (Enbrel) induces a rapid and sustained decline in disease activity in the majority of patients with refractory rheumatoid arthritis (RA). In these patients neutralization of TNFalpha and lymphotoxin (LT), previously termed TNFbeta is mediated by etanercept itself, as well as by naturally occurring soluble TNF receptors. However, the clinical response to treatment with etanercept may vary. Previously, pharmacokinetic studies have focused on the molar concentrations of etanercept, but very little is known about the kinetics of bioactive etanercept in patients treated with etanercept. The purpose of this study was to evaluate kinetics, including inter- and intraindividual variations of the total TNF binding capacity, in RA patients who were on a standard treatment schedule with etanercept. METHODS: Plasma samples were collected daily from 16 RA patients who were in the steady-state phase during treatment with etanercept 25 mg subcutaneous once (n = 2) or twice (n = 14) weekly. The inflammatory activity, including Health Assessment Questionnaire (HAQ) score, numbers of painful and swollen joints, and ESR, was assessed at inclusion; CRP was measured on a daily basis. The samples were incubated with human recombinant LT to a concentration of 1000 pg/mL and the levels of detectable LT were measured by ELISA specific for free LT. The LT binding capacity (LTBC) was expressed in arbitrary units (AU) as the percentage value of bound LT to added LT. RESULTS: The median LTBC values measured during the treatment schedule from Day 1 (before the injection) to Day 4 (before the next injection) were 47 AU. The LTBC values in each individual patient generally remained fairly stable through the treatment schedule, and there were no significant differences in LTBC levels in samples obtained on a daily basis during the treatment schedule. However, a pronounced variation between the patients was noticed with LTBC values ranging from 10-82 AU (coefficient of variation=38%). No significant association was found between LTBC levels and clinical measures of disease activity, including HAQ and numbers of swollen or painful joints. However, among patients with high LTBC levels (> or =65 AU), elevated levels of ESR and CRP were less frequent (0%) compared with patients who had lower LTBC levels, in which the frequencies of elevated ESR and CRP were 53% and 37%, respectively. Soluble TNF receptor 1 (sTNFR1) remained stable between the injections and correlated with the number of swollen joints, but did not correlate with LTBC values. CONCLUSION: LTBC levels appeared stable in each individual RA patient who was on the standard treatment schedule with weekly injections of etanercept, but the inter-individual variations were considerable.

Adult↗

PubMed2004

Circulating ghrelin levels in the newborn are positively associated with gestational age.

OBJECTIVE: Ghrelin exerts potent GH-releasing activity and stimulates food intake. Circulating ghrelin levels are increased in anorexia and cachexia, reduced in obesity and restored by weight recovery. Newborns are characterized by GH hypersecretion associated with low IGF-I levels reflecting peripheral GH resistance. STUDY DESIGN: The aim of our study was to measure cord ghrelin levels in 117 newborns appropriate for gestational age, born either at term or preterm. RESULTS: Ghrelin levels in cord blood (median; 25th-75th centile: 327.6; 206.0-413.0 pg/ml) were higher (P < 0.0001) than those in maternal blood at delivery (133.0; 89.0-173.7 pg/ml), without gender differences. A positive correlation between ghrelin levels in mothers and newborns (r = 0.26, P < 0.01) was observed. Ghrelin levels in newborns born at term (399.0; 229.0-438.0 pg/ml) were remarkably higher (P < 0.0001) than those in born preterm (208.0; 144.5-278.9 pg/ml). A clear positive association was present between ghrelin levels and gestational age. No association between ghrelin and GH, IGF-I, insulin, glucose and leptin levels were found. CONCLUSIONS: Cord ghrelin levels show clear gestational age-related dependency. The lack of any direct relationship between ghrelin and anthropometric or biochemical parameters in adequate for gestational age newborns does not support the hypothesis that ghrelin has major role in foetal GH secretion and growth.

Adult↗

PubMed2004

Ghrelin gene polymorphisms and ghrelin, insulin, IGF-I, leptin and anthropometric data in children and adolescents.

BACKGROUND: Previous investigations on the ghrelin gene reported three common polymorphisms (Arg51Gln, Leu72Met, and Gln90Leu), but their role in overweight and obese individuals remains to be clarified. OBJECTIVE: To ascertain whether these genetic variants could influence ghrelin secretion and play a part in predisposing to earlier onset of obesity or in modulating the overweight phenotype in childhood. DESIGN AND METHODS: Mutational analysis of the entire ghrelin gene and total and acylated plasma determinations were performed in 81 obese or overweight children and adolescents (46 were obese and 35 overweight: Ob/Ow). We also recruited 168 normal-weight healthy controls (72 young adults and 96 children) for mutational or plasma ghrelin analysis. RESULTS: Median total and acylated plasma ghrelin concentrations were significantly lower in Ob/Ow individuals than in controls (175 pg/ml compared with 345 pg/ml, P<0.0001, and 95 pg/ml compared with 114 pg/ml, P<0.0001, respectively). The ghrelin gene variants showed similar allele frequencies in the Ob/Ow individuals and in controls; in the former, they were not associated with any change in total and acylated circulating ghrelin concentrations or anthropometric data. The Leu72Met status was associated with a positive family history for obesity (75% for Leu72Met compared with 39% for Leu72Leu, P=0.03) and with a greater percentage of newborns born 'large for gestational age' (33% for Leu72Met compared with 5% for Leu72Leu, P=0.03), but in the control group it was related to a lower mean body mass index z-score (-0.03 for Leu72Met and -0.47 for Leu72Leu, P=0.04). CONCLUSION: Our present findings do not support the hypothesis that the ghrelin gene polymorphisms have a relevant impact in the secretion of total and acylated ghrelin.

Adolescent↗

PubMed2003

Analysis of the therapeutic efficacy of different doses of budesonide in patients with active Crohn's ileocolitis depending on disease activity and localization.

BACKGROUND AND AIMS: The nonsystemic steroid budesonide has been used to treat active ileocecal and ileocolonic Crohn's disease (CD). This study investigated the optimal budesonide dose using a pH-dependent release formulation. The goal of treatment was the remission of CD (CDAI <150) within 6 weeks of treatment. PATIENTS AND METHODS: The study was of randomized, double-blind, dose-finding design. Patients with active CD ileocolitis without steroid pretreatment were treated with 3x2 mg ( n=39), 3x3 mg ( n=33), or 3x6 mg ( n=32) oral pH-modified released budesonide daily. RESULTS: The remission rates after 6 weeks were 36% with 3x2 mg, 55% with 3x3 mg, and 66% with 3x6 mg. Significantly more patients were in remission while treated with 3x6 mg than with 3x2 mg budesonide/day. Subgroup analyses revealed that patients with high disease activity (CDAI >/= 300) or ileocolonic disease with disease manifestation distal to the transverse colon responded better to the highest budesonide dose. CONCLUSION: Oral pH-modified released budesonide shows a dose-dependent effectiveness in patients with active ileocolonic CD. In the majority of patients 9 mg budesonide per day is sufficient. However, in patients with highly active disease or ileal disease with distal colonic manifestation higher doses of budesonide could increase the therapeutic response

Adult↗

PubMed2003

Circulating ghrelin levels in newborns are not associated to gender, body weight and hormonal parameters but depend on the type of delivery.

Ghrelin, a new gastric-derived hormone, probably plays a major role in managing energy balance and the neuroendocrine response to starvation. Information about the age-related variation in ghrelin secretion is scanty. We measured circulating ghrelin levels in 93 full term newborns adequate for gestational age, in 39 normal children and in 19 lean healthy adults. Our findings demonstrate that ghrelin levels are independent of age and gender from birth to adulthood. Interestingly, ghrelin secretion at birth is not associated to body weight and hormonal parameters such as GH, insulin and leptin levels. On the other hand, ghrelin levels seem dependent on the type of delivery, being lower in newborns after caesarean section with respect to those after normal delivery.

Adult↗

PubMed2003

In vitro detection of (S)-naproxen and ibuprofen binding to plaques in the Alzheimer's brain using the positron emission tomography molecular imaging probe 2-(1-[6-[(2-[(18)F]fluoroethyl)(methyl)amino]-2-naphthyl]ethylidene)malononitrile.

Epidemiological studies have suggested that the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) reduces the relative risk of Alzheimer's disease (AD). The possible neuroprotection by NSAIDs in AD is generally attributed to anti-inflammatory activity. An additional mode of drug action may involve anti-aggregation of beta-amyloid (Abeta) peptides by commonly used NSAIDs. We utilized in vitro competition assays, autoradiography, and fluorescence microscopy with AD brain specimens to demonstrate concentration-dependent decreases in the binding of the in vivo molecular imaging probe, 2-(1-[6-[(2-[(18)F]fluoroethyl)(methyl)amino]-2-naphthyl]ethylidene)malononitrile ([(18)F]FDDNP), against (S)-naproxen and (R)- and (S)-ibuprofen (but not diclofenac) to Abeta fibrils and ex vivo Abeta senile plaques. Conversely, in vitro amyloid dyes Congo Red and Thioflavine T were demonstrated in the same experiments not to bind to the FDDNP binding site. FDDNP and the NSAIDs that share the same binding site also exhibit anti-aggregation effects on Abeta peptides, suggesting that the shared binding site on Abeta fibrils and plaques may be a site of anti-aggregation drug action. Our results indicate for the first time the binding of select NSAIDs to plaques, specifically to the binding site of the molecular imaging probe [(18)F]FDDNP. Our understanding of the molecular requirements of FDDNP binding may help in the optimization of the Abeta anti-aggregation potency of experimental drugs. [(18)F]FDDNP has been used to image plaques in vivo with positron emission tomography (PET), and investigations into the influence of Abeta anti-aggregation on the risk-reduction effects of NSAIDs on AD could utilize [(18)F]FDDNP and PET in determining the occupancy rate of NSAIDs and experimental drugs in plaques in the living brain of AD patients.

Aged↗