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Biomedical subjects

A Petri

Publications and source records attributed to A Petri.

At least 19 recordsLinked to original sources
PubMed2002

Microscopic two-dimensional lattice model of dimer granular compaction with friction.

We study by Monte Carlo simulation the compaction dynamics of hard dimers in two dimensions under the action of gravity, subjected to vertical and horizontal shaking, considering also the case in which a friction force acts for horizontal displacements of the dimers. These forces are modeled by introducing effective probabilities for all kinds of moves of the particles. We analyze the dynamics for different values of the time tau during which the shaking is applied to the system and for different intensities of the forces. It turns out that the density evolution in time follows a stretched exponential behavior if tau is not very large, while a power law tail develops for larger values of tau. Moreover, in the absence of friction, a critical value tau(*) exists, which signals the crossover between two different regimes: for tau tau(*) it reaches logarithmically a maximal saturation value. Such behavior smears out when a finite friction force is present. In this situation the dynamics is slower and lower asymptotic densities are attained. In particular, for significant friction forces, the final density decreases linearly with the friction coefficient. We also compare the frictionless single tap dynamics to the sequential tapping dynamics, observing in the latter case an inverse logarithmic behavior of the density evolution, as found in the experiments.

Journal Article↗
PubMed2002

Pyogenic liver abscess -- 20 years' experience. Comparison of results of treatment in two periods.

BACKGROUND AND AIMS: Our aim is to give an audit of our experience over the past two decades in the form of a retrospective study. PATIENTS/METHODS: In two equal periods between 01.01.1982 and 31.03.2001, 56 patients (37 males and 19 females) with pyogenic liver abscess were treated. Image-guided percutaneous drainage was performed in 22.2%/20.6% of the patients; the remainder were treated with open drainage with or without biliary tract reconstruction and liver resection. For antibiotic perfusion of the liver an umbilical vein cannula was inserted in 40.7%/24.1%. Microbiological findings, types of therapy, complications and mortality, etiology, patient characteristics, symptoms, and laboratory data were investigated. The results in the two groups were compared and analyzed statistically. RESULTS: The most common cause of abscess, biliary disease, was seen more often in the second period. Solitary liver abscesses were more frequent. The only characteristic biochemical finding was an elevated alkaline phosphatase level. There were more positive cultures in the second period (70.4%/79.3%), and the number of Escherichia coli or Enterobacter aerogenes infections also increased. In the first period the mortality was 18.5%, whereas in the second no patients were lost. CONCLUSION: We suggest the importance of individualized therapy based on an early and exact diagnosis. The first treatment step should be image-guided drainage, but under well-defined circumstances open drainage can also be performed with good results.

Adult↗
PubMed2002

Stretched exponential relaxation in a diffusive lattice model.

We studied the single dimer dynamics in a lattice diffusive model as a function of particle density in the high densification regime. The mean square displacement is found to be subdiffusive both in one and two dimensions. The spatial dependence of the self-part of the van Hove correlation function displays as a function of r a single peak and signals a dramatic slow down of the system for high density. The self-intermediate scattering function is fitted to the Kohlrausch-Williams-Watts law. The exponent beta extracted from the fits is density independent while the relaxation time tau follows a scaling law with an exponent 2.5.

Journal Article↗
PubMed2002

Circulating ghrelin levels as function of gender, pubertal status and adiposity in childhood.

Ghrelin, a natural GH secretagogue, exerts remarkable endocrine and non-endocrine 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 to insulin secretion, enhanced in anorexia and reduced in obesity. Ghrelin levels in childhood have never been evaluated. We measured morning ghrelin levels after overnight fasting in 29 healthy lean children (NC) and in 36 obese children (OBC). The results were compared with those recorded twice in 3 different sessions in healthy lean adults (NA). In NA ghrelin levels showed good within-subject reproducibility without gender-related differences. Ghrelin levels in NC [(median; 25 degrees -75 degrees centile): 426.0; 183.0-618.0 pg/ml] were similar to those in NA (380.5; 257.7-551.7 pg/ml). Ghrelin levels in OBC (229.5; 162.5-339.5 pg/ml) were lower (p<0.03) than in NC (426.0; 183.0-618.0 pg/ml). Both in NC and in OBC, ghrelin levels were independent of gender and pubertal status. In all children, ghrelin levels were negatively associated (p<0.05) to weight excess (r=-0.24), insulin (r=-0.28) and IGF-I (r=-0.4) levels. In conclusion, these findings demonstrate that morning ghrelin levels after overnight fasting show good within-subject reproducibility, and are similar in both sexes and do not vary from childhood to adulthood. In childhood, circulating ghrelin levels are reduced in obese subjects being negatively correlated to overweight and insulin secretion.

Adult↗
PubMed2002

[Secular trend of puberty].

The aim of our study was to evaluate the age of the onset of pubertal characteristics in a population of Northern Italy and to compare our data with the pubertal staging scale defined by Tanner in 1976. These observations may help us to verify if even in Italy there is a positive secular change in sexual maturation, as has been observed in many European countries. We studied 3510 children (1868 males and 1642 females) aged 6-15 years, born between 1983 and 1996. In every subject sexual maturity was evaluated according to Tanner stages. We calculated the percentile distribution for ages of attainment of B2 and PH2 stages for females and G2, PH2 and testicular volume = or >4 ml (VT4) for males. In females the percentile values for B2 were: 3rd=8.1, 50th=10.5, and 97th=12.6 years. In males the percentile values for G2 and VT4 were: 3rd=8.8 and 9.1 years respectively, 50th=11 years, and 97th=13.4 and 13.3 years respectively. 3rd, 50th, and 97th centiles for pubic hair stage 2 were 8.1, 10.6 and 12.6 years for females and 8.8, 11.2 and 13.4 years for males. For all stages an earlier pubertal development was seen in comparison with Tanner data. One hundred-twenty-five girls had already reached menarche. Median (interquartile range) age at menarche was 11.9 (11.4-12.4) years showing a decrease compared with Tanner values. Our data clearly demonstrate a positive secular trend in pubertal development and point out the need of having updated references values of the timing of sexual maturation for the whole Italian population.

Adolescent↗
PubMed2001

Biochemical and antioxidant changes in plasma and erythrocytes of pentathlon horses before and after exercise.

Physical exercise in the horse induces a series of normal physiological and biochemical adaptations. Increasing metabolism and oxygen uptake may induce oxidative stress in various organs. The aim of this study was to examine exercise-induced changes in some plasma and RBC biochemical and antioxidant variables in pentathlon horses. Blood samples were taken from 14 horses before, immediately after, and 24 hours after competing in two 1-minute runs of intense exercise over jumps. The peak intensity periods were preceded by a 20-minute warm-up and separated by a 20-minute break. The following plasma biochemical analytes were determined: total protein, uric acid, and lactate concentrations, and lactate dehydrogenase (LDH) and creatine kinase (CK) activities. Total antioxidant status (TAS) and the ferric reducing ability of plasma (FRAP) also were measured. Thiobarbituric acid-reactive substances (TBARS), reduced glutathione (GSH), and total protein concentrations, and glutathione peroxidase (GSHPx) and superoxide dismutase (SOD) activities were determined in RBC hemolysates. Significantly increased concentrations of total protein, lactate, and FRAP, and increased activities of CK and LDH were observed immediately postexercise compared with pre-exercise samples (P<0.05). All results returned to approximately initial values after 24 hours of rest. RBC GSH and TBARS concentrations did not change immediately after exercise, but decreased after 24 hours of rest (P<0.05). Plasma uric acid and FRAP values were positively correlated in a linear model (r = 0.78). In summary, the type of exercise applied in this study, which can be considered quite usual for pentathlon horses, caused detectable biochemical and lipid peroxidative changes in plasma and RBCs. FRAP and TAS values changed in opposite directions, indicating that when antioxidant capacity is assessed using different methods, highly different results may be obtained.

Journal Article↗
PubMed2000

Lipoma of the liver: a differential-diagnostic problem.

BACKGROUND AND AIMS: Lipomatous tumors of the liver are extremely rare; most of them are found incidentally at autopsy. Appropriate methods of the diagnosis of these lesions are ultrasonography (US), computed tomography (CT) and biopsy. CASE REPORT: The case of a 65-year-old man who had undergone an upper-rectum resection because of exulcerated adenocarcinoma of the rectum is described. Six months later, routine control examination revealed a solid tumor in the left lobe of the liver. The tumor was not demonstrated by either sonography or CT before the operation. Repeated US, CT scan and fine-needle biopsy could not exclude the possibility of a metastatic tumor secondary to previous malignancy. The lesion was removed by wedge resection and was proven to be a lipoma. CONCLUSION: Despite adequate preoperative examination (CT, biopsy and US), an anamnestic adenocarcinoma of the rectum can lead to inappropriate therapy. The inadequate result of our therapeutic policy can be explained by the extremely rare incidence of lipoma of the liver.

Adenocarcinoma↗
PubMed2000

Comparison of the vasorelaxing effect of cromakalim and the new inodilator, levosimendan, in human isolated portal vein.

In the present study the vasorelaxing capacity of cromakalim, an ATP-sensitive potassium-channel (KATP channel) activator, and that of levosimendan, a new positive inotropic and vasodilating drug with calcium sensitizing and potassium-channel-activating properties, were compared in human isolated portal vein. Based on the 50% effective concentrations (EC50), levosimendan was found to be about 16-fold more potent (EC50 = 0.281+/-0.03 microM) as a relaxing agent than cromakalim (EC50 = 4.53+/-0.12 microM) in noradrenaline-precontracted portal venous preparations. Glibenclamide, the known inhibitor of KATP channels, was able to prevent the cromakalim-induced venodilation completely. Glibenclamide (15 microM) decreased the quasi-maximal effect of levosimendan (at 1.27 microm by about 60%) and also the effects of those submicromolar concentrations of the inodilator (at 0.1 microM by 23%, at 0.3 microM by 27% and at 0.7 microM by 19%, on average) which were therapeutically effective in preliminary human studies. These findings indicate that, in the human portal vein, both cromakalim and levosimendan are powerful vasorelaxants and that a considerable part of the relaxing effect induced by levosimendan is of cromakalim type.

Adolescent↗
PubMed2000

Primary mono-layer cell cultures as model system for studying of environmental toxic agents: organochlorine compounds.

Organic pollution of water and soil has various harmful effects on biological systems (1). Chlorine substituted benzol compounds are one these xenobiotic substances, which are toxic to the environment (2). They can also accumulate in plant and animal tissues (3), which provides ample reason to study the effects of sublethal doses of chloro-benzols on various cell cultures. In this study the toxic effects of chloro-benzols were investigated on avian fibroblast and mammalian hepatocyte cultures. The fibroblast cultures were prepared from eggs preadapted to chloro-benzol during a fourteen-day-long incubation period. The Wistar rat hepatocyte monolayer cultures were exposed to a direct treatment of 1,2,4-tri-chloro-benzol (0.01 microgram/ml-1 microgram/ml) for 3 hours. Following the treatment with chloro-benzol, the viability of the cells was measured, together with lactic dehydrogenase activity, in both kinds of cultures. The effect of tri-chloro-benzol treatment on chicken eggs was not significant. The cells of chicken embryos were not damaged after the 1,2,4-tri-chloro-benzol treatment. The hepatocyte cultures showed the toxic effects of 1,2,4-tri-chloro-benzol after the direct and acute treatment. The cell viability decreased and the LDH activity increased significantly. These results show that the primary cell cultures are suitable for studying the effects of organochlorine compounds.

Animals↗
PubMed1999

Catalytic asymmetric dihydroxylation of alkenes induced by polymeric chiral ligands

Chiral monomers, bearing different quinidine derivatives, were copolymerized with achiral monomers, producing insoluble copolymers which were used for the dihydroxylation of styrene as standard substrate. The structure of the polymeric insoluble support was found to be of great importance in determining the handling, efficiency, and enantioselectivity of the catalyst. The comparison with a soluble model compound showed that the insoluble polymer-bound ligand approach is very promising for both small- and large-scale synthesis of optically active vicinal diols. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗
PubMed1999

Gene therapy for lung cancer.

In the pre-clinical research into the development of gene therapy for cancer, different strategies have evolved and shown promising results in the laboratory. However, most of these strategies will need further refinement to obtain clinical success. This is partly due to the lack of suitable vector systems which specifically can deliver the therapeutic gene to the target cells, and ensure expression of the therapeutic gene. In this review we will give an introduction to different strategies used in cancer gene therapy for neoplasms of the lung, and focus on how to target gene delivery to disseminated lung cancer cells. Tumor specific gene expression can be accomplished at different levels. One way to accomplish targeted gene delivery is by coupling of receptor specific ligands to the vector. Specific gene delivery to cells expressing the target receptor will occur by receptor mediated endocytosis of the vector. Further restriction of gene expression to cancer cells can be accomplished by utilizing promoters predominantly active in tumors. When gene therapy is targeted at different levels, efficient gene delivery to disseminated cancer cells by systemic vector administration will be an attractive future prospect.

Animals↗
PubMed1999

The impact of gender, puberty and body mass on reference values for urinary growth hormone (GH) excretion in normally growing non-obese and obese children.

OBJECTIVE: There is a lack of normal reference data on urinary GH (u-GH) excretion in children. We have investigated the impact of age, gender, pubertal development and body mass on reference values for u-GH excretion in normally growing non-obese and obese children. STUDY DESIGN: u-GH levels were evaluated in 1153 healthy normal children (aged 5-14) and in 684 obese children (body mass index, BMI: > 75th). u-GH levels (ng/8 h) were determined by ELISA as the mean value of three consecutive first morning voidings. RESULTS: Reference values (5-95th centile) for u-GH excretion in obese and non-obese children of both sexes are reported. In normal prepubertal children median u-GH levels were relatively stable and superimposable in the two sexes; subsequently, u-GH levels increased, reaching a peak value at 13 years in both sexes. Significant increments (P < 0.0001) in u-GH levels were shown at B2 for females and at G3 for males. A slight decline was evident at 14 years. In obese children, median u-GH concentrations were significantly lower than those recorded in normal children of prepubertal age and at all stages of puberty (except in females at B2), in spite of their comparable normal height. u-GH levels significantly increased at puberty also in obese children, although the pubertal rise was significantly (P < 0.001) lower (1.7-fold in both sexes) than that observed in normal children (2.5-fold in boys and 2.3-fold in girls). A multiple regression analysis showed that both chronological age (beta: 0.20), BMI (beta: - 0.11), gender (beta: - 0.04) and pubertal stage (beta: 0.25) contributed significantly to the physiological variation in u-GH levels (multiple R: 0.44, P < 0.00001). CONCLUSIONS: This study provides reference values for u-GH in normally growing non-obese and obese children, analysing the impact of gender, puberty and body mass on this parameter. In agreement with previous studies, which demonstrate blunted GH-responses to provocative stimuli and reduced nocturnal GH concentration, obese children have significantly lower u-GH levels than age-matched normal weight children, both before and during puberty.

Adolescent↗
PubMed1999

[Some aspects of drinking water fluoridation].

Increased fluoride concentration in different ecological systems results from cool combustion and fluoridation of water in the public supply system. In Wrocław, water has been fluoridated for thirty years to achieve the concentration of 1 mg F per litre for dental caries protection. Over that time the concentration of fluoride ion has not been surveyed in serum or urine of the Wrocław population. The prevention of dental caries using fluoride-containing tooth paste as well as fluoride tables and gels is strongly recommended.

Cariostatic Agents↗
PubMed1997

[The long-term prognosis of patients with acute chest pain of various origins].

A total of 204 patients with acute chest pain, but without myocardial infarction (non-AMI) were included. In 56 a definite diagnosis was obtained within 24-48 hours of admission. The remaining 148 patients underwent a comprehensive examination program. Ischaemic heart disease (IHD) was diagnosed in 64 patients, 81 had gastro-oesophageal disorders, 58 chest wall disorders, nine pericarditis, five pulmonary embolism, four pneumonia/pleuritis, three pulmonary cancer, two dissecting aortic aneurysm, one aortic stenosis and one herpes zoster. During 33 months of follow-up, 31 of the 64 patients with IHD had a cardiac event (cardiac deaths, non-fatal AMI, bypass surgery or PTCA) whereas only three events occurred among the 140 patients without IHD (p < 0.00001). However, the frequency of readmissions and of recurrent episodes of chest pain were similar in the three major diagnostic groups (NS). It is concluded that the high risk subset of a non-AMI population can be identified by means of non-invasive cardiac examination. The remainder who have other diagnoses are at low risk. However, the morbidity is high with frequent readmissions and recurrent episodes of chest pain, and the need for development of strategies with regard to diagnosis and treatment of these patients is emphasized.

Acute Disease↗