Voxel model of a rabbit: assessment of absorbed doses in organs after CT examination performed by two different protocols.

The objective of this work was to assess absorbed doses in organs and tissues of a rabbit, following computed tomography (CT) examinations, using a dedicated 3D voxel model. Absorbed doses in relevant organs were calculated using the MCNP5 Monte Carlo software. Calculations were perfomed for two standard CT protocols, using tube voltages of 110 kVp and 130 kVp. Absorbed doses were calculated in 11 organs and tissues, i.e., skin, bones, brain, muscles, heart, lungs, liver, spleen, kidney, testicles, and fat tissue. The doses ranged from 15.3 to 28.3 mGy, and from 40.2 to 74.3 mGy, in the two investigated protocols. The organs that received the highest dose were bones and kidneys. In contrast, brain and spleen were organs that received the smallest doses. Doses in organs which are stretched along the body did not change significantly with distance. On the other hand, doses in organs which are localized in the body showed maximums and minimums. Using the voxel model, it is possible to calculate the dose distribution in the rabbit's body after CT scans, and study the potential biological effects of CT doses in certain organs. The voxel model presented in this work can be used to calculated doses in all radiation experiments in which rabbits are used as experimental animals.

Simulation of H p (10) and effective dose received by the medical staff in interventional radiology procedures.

Interventional radiology and cardiology are widespread employed techniques for diagnosis and treatment of several pathologies because they avoid the majority of the side-effects associated with surgical treatments, but are known to increase the radiation exposure to patient and operators. In recent years many studies treated the exposure of the operators performing cardiological procedures. The aim of this work is to study the exposure condition of the medical staff in some selected interventional radiology procedures. The Monte Carlo simulations have been employed with anthropomorphic mathematical phantoms reproducing the irradiation scenario of the medical staff with two operators and the patient. A personal dosemeter, put on apron, was modelled for comparison with measurements performed in hospitals, done with electronic dosemeters, in a reduced number of interventional radiology practices. Within the limits associated to the use of numerical anthropomorphic models to mimic a complex interventional procedure, the personal dose equivalent, H p (10), was evaluated and normalised to the simulated Kerma-Area Product, KAP, value, indeed the effective dose has been calculated. The H p (10)/KAPvalue of the first operator is about 10 µSv/Gy.cm2, when ceiling shielding is not used. This value is calculated on the trunk and it varies of +/-30% moving the dosemeter to the waist or to the neck. The effective dose, normalised to the KAP value, varies between 0.03 and 0.4 µSv/Gy.cm2. Considering all the unavoidable approximation of this kind of investigations, the comparisons with hospital measurement and literature data showed a good agreement allowing to use of the present results for dosimetric characterisation of interventional radiology procedures.

Conventional sunscreen application does not lead to sufficient body coverage.

OBJECTIVE: This study aimed to assess sunscreen application habits and relative body coverage after single whole body application. METHODS: Fifty-two healthy volunteers were asked to use the test product once, following their usual sunscreen application routine. Standardized UV photographs, which were evaluated by Image Analysis, were conducted before and immediately after product application to evaluate relative body coverage. In addition to these procedures, the volunteers completed an online self-assessment questionnaire to assess sunscreen usage habits. RESULTS: After product application, the front side showed significantly less non-covered skin (4.35%) than the backside (17.27%) (P = 0.0000). Females showed overall significantly less non-covered skin (8.98%) than males (13.16%) (P = 0.0381). On the backside, females showed significantly less non-covered skin (13.57%) (P = 0.0045) than males (21.94%), while on the front side, this difference between females (4.14%) and males (4.53%) was not significant. CONCLUSION: In most cases, the usual sunscreen application routine does not provide complete body coverage even though an extra light sunscreen with good absorption properties was used. On average, 11% of the body surface was not covered by sunscreen at all. Therefore, appropriate consumer education is required to improve sunscreen application and to warrant effective sun protection.

Do interictal microembolic signals play a role in higher cortical dysfunction during migraine aura?

INTRODUCTION: The aim of this study was to evaluate the prevalence and clinical impact of interictal microembolic signals (MES) in patients suffering from migraine with higher cortical dysfunction (HCD), such as language and memory impairment, during an aura. PATIENTS AND METHODS: This study was carried out on 34 migraineurs with language and memory impairment during aura (HCD group), 31 migraineurs with only visual or visual and somatosensory symptoms during aura (Control group I), and 34 healthy controls (Control group II). We used a Doppler instrument to detect microemboli. Demographic data, disease features and the detection of MES between these groups, as well as the predictors of HCD during the aura, were analyzed. RESULTS: The duration of aura was longer and the frequency of aura was higher among patients with language and memory impairment during aura compared to Control group I. MES was detected in 29.4% patients from the HCD group, which was significantly higher compared to 3.2% in Control group I and 5.9% in Control group II. Regarding the absence or presence of MES, demographic and aura features were not different in the HCD subgroups. A longer duration of aura, the presence of somatosensory symptoms during the aura and the presence of interictal MES were independent predictors of HCD during the aura. CONCLUSION: The present findings indicate that HCD and MES are related in patients with migraine with aura. Further research is needed to better understand the exact pathophysiological mechanism.

Interaction with gravitropism, reversibility and lateral movements of phototropically stimulated potato shoots.

Phototropic (PT) and gravitropic (GT) bending are the two major tropic movements that determine the spatial position of potato shoots. We studied PT bending of potato plantlets grown under long-day photoperiods in several prearranged position setups providing different interactions with the GT response. Starting with the standard PT stimulation setup composed of unilateral irradiation of vertically positioned shoots, experiments were also done in antagonistic and synergistic setups and in treatments with horizontal displacement of the light source. In the standard setup, PT bending suppressed the GT bending, which could occur only if the PT stimulation was cancelled. The antagonistic position, with phototropism and gravitropism attempting to bend shoots in opposite directions, showed phototropism and gravitropism as independent bending events with the outcome varying throughout the day reflecting diurnal changes in the competence of individual tropic components. Whilst gravitropism was constant, phototropism had a marked daily fluctuation of its magnitude with a prominent morning maximum starting an hour after the dawn in the growth room and lasting for the next 6 h. When phototropism and gravitropism were aligned in a synergistic position, stimulating shoot bending in the same direction, there was little quantitative addition of their individual effects. The long period of morning PT bending maximum enabled multiple PT bending events to be conducted in succession, each one preceded by a separate lag phase. Studies of secondary PT events showed that potato plantlets can follow and adjust their shoot position in response to both vertical and horizontal movements of a light source. PT bending was reversible, since the 180° horizontal change of a blue light (BL) source position resulted in reversal of bending direction after a 20-min-long lag phase.

Obesity dilemma in the global burden of cardiovascular diseases.

AIM: Obesity is a well-known risk factor in the cardiovascular disease continuum. However, its clinical effects are multimodal, perplexed and non-unanimously understood. Our aim was to assess the prevalence and effects of obesity on the cardiometabolic risk factors and systolic function of left ventricle ejection fraction (LVEF) in patients scheduled for cardiovascular rehabilitation. METHODS: A cohort of 302 consecutive patients recently treated for ischaemic or valvular heart disease was matched according to the existence of obesity, defined with body mass index (BMI ≥ 30 kg/m(2) ; n = 90 vs. 212), and the advanced grade of obesity (BMI ≥ 35 kg/m(2) ; n = 19 vs. 283). Nutritional risk screening was performed using the standardised NRS-2002 tool. RESULTS: The mean age of patients was 62.4 ± 11.2 (range 23-86) years; there were more men than women 244 (80.8%) : 58 (19.2%). Group of obese conveyed higher prevalence of ischaemic heart disease than non-obese (OR = 2.69; 95% CI: 1.01-7.20; p = 0.048); while the difference was insignificant for the advanced grade of obesity (n = 17; 89.5%) vs. controls (n = 233; 82.3%; p > 0.05). There was no significant difference in prevalence of other comorbidities (diabetes, glucose intolerance, hypercholesterolaemia, chronic renal and chronic obstructive pulmonary disease) between studied groups (p > 0.05). Utilisation of lipid-lowering drugs was of similar range between the studied groups (p > 0.05), respectively. LVEF (%) was 50.5 ± 8.2 vs. 50.7 ± 7.7 (p > 0.05) and 50.6 ± 7.8 vs. 49.6 ± 10.9 (p > 0.05; Rho = 0.001; p > 0.05), respectively. CONCLUSION: In studied set of patients, BMI positively correlated with left ventricle dimension and thickness. No significant connection of obesity was found with the prevalence of chronic comorbidities, increased nutritional risk, laboratory diagnostics or systolic function of left ventricle. Existence of obesity paradox in clinical practice was in part reaffirmed with our study.

ON THE PLACEMENT OF APRON DOSEMETERS AND DOSE ASSESSMENT IN INTERVENTIONAL CARDIOLOGY PROCEDURES: PRELIMINARY RESULTS.

Personnel involved in interventional practices are likely to be exposed to higher radiation doses than other workers in the medical field. Personnel monitoring and radiation protection measures play a crucial role in keeping these doses below the limits. EURADOS (European Radiation Dosimetry Group) Working Group 12 performed a series of investigations showing how the complexity of the scattered field reaching the operators can influence the doses to the operators. The present work was aimed at determining the possible effects on the registered doses of the scattered field and the actual position of a dosemeter on apron. This study has been performed through Monte Carlo simulations and it was validated through measurements. It does not claim to identify the 'best' position for the dosemeter, but to assess the variability of its response, showing how a variability of the order of +/- 30% to 40 should be taken into account.

Diet-induced gene expression of isolated pancreatic islets from a polygenic mouse model of the metabolic syndrome.

AIMS/HYPOTHESIS: Numerous new genes have recently been identified in genome-wide association studies for type 2 diabetes. Most are highly expressed in beta cells and presumably play important roles in their function. However, these genes account for only a small proportion of total risk and there are likely to be additional candidate genes not detected by current methodology. We therefore investigated islets from the polygenic New Zealand mouse (NZL) model of diet-induced beta cell dysfunction to identify novel genes and pathways that may play a role in the pathogenesis of diabetes. METHODS: NZL mice were fed a diabetogenic high-fat diet (HF) or a diabetes-protective carbohydrate-free HF diet (CHF). Pancreatic islets were isolated by laser capture microdissection (LCM) and subjected to genome-wide transcriptome analyses. RESULTS: In the prediabetic state, 2,109 islet transcripts were differentially regulated (>1.5-fold) between HF and CHF diets. Of the genes identified, 39 (e.g. Cacna1d, Chd2, Clip2, Igf2bp2, Dach1, Tspan8) correlated with data from the Diabetes Genetics Initiative and Wellcome Trust Case Control Consortium genome-wide scans for type 2 diabetes, thus validating our approach. HF diet induced early changes in gene expression associated with increased cell-cycle progression, proliferation and differentiation of islet cells, and oxidative stress (e.g. Cdkn1b, Tmem27, Pax6, Cat, Prdx4 and Txnip). In addition, pathway analysis identified oxidative phosphorylation as the predominant gene-set that was significantly upregulated in response to the diabetogenic HF diet. CONCLUSIONS/INTERPRETATION: We demonstrated that LCM of pancreatic islet cells in combination with transcriptional profiling can be successfully used to identify novel candidate genes for diabetes. Our data strongly implicate glucose-induced oxidative stress in disease progression.

MCNPX CALCULATIONS OF SPECIFIC ABSORBED FRACTIONS IN SOME ORGANS OF THE HUMAN BODY DUE TO APPLICATION OF 133Xe, 99mTc and 81mKr RADIONUCLIDES.

Monte Carlo simulations were performed to evaluate treatment doses with wide spread used radionuclides 133Xe, 99mTc and 81mKr. These different radionuclides are used in perfusion or ventilation examinations in nuclear medicine and as indicators for cardiovascular and pulmonary diseases. The objective of this work was to estimate the specific absorbed fractions in surrounding organs and tissues, when these radionuclides are incorporated in the lungs. For this purpose a voxel thorax model has been developed and compared with the ORNL phantom. All calculations and simulations were performed by means of the MCNP5/X code.

The association between early menopause and risk of ischaemic heart disease: influence of Hormone Therapy.

UNLABELLED: Randomised clinical trials find no protection against development of ischaemic heart disease by use of Hormone Therapy (HT) after the age of 50 years. Observational studies suggest that early menopause is a risk factor for ischaemic heart disease. Yet, a clinical very relevant question is whether HT reduces this risk associated with early menopause. OBJECTIVE: To analyse whether early menopause based on various causes are independent risk factors for ischaemic heart disease, and to investigate whether the risks are modified by use of HT. METHODS: In a prospective cohort study questionnaires were mailed to Danish female nurses above 44 years of age in 1993. Information on menopause, use of HT and lifestyle was obtained. In total 19,898 (86%) nurses fulfilled the questionnaire, among them 10.533 were postmenopausal with definable menopausal age, free of previous ischaemic heart disease, stroke or cancer. Through individual linkage to national register incident cases of ischaemic heart disease were identified until end of 1998. RESULTS: Menopause below both age 40 and 45 was associated with an increased risk of ischaemic heart disease, seeming most pronounced for women who had an early ovariectomy but also among spontaneous menopausal women. Generally HT did not reduce the risk except for the early-ovariectomised women, where no increased risk of ischaemic heart disease for HT users was found. CONCLUSION: We found an increased risk of ischaemic heart disease associated with early removal of the ovaries that might be reduced with HT. The present study need confirmation from other studies but suggests that early ovariectomised women could benefit from HT.

Interactive visualization of 3D fields and images on inexpensive workstations using VRML.

The visualization of volumetric medical images and static or time-dependent vector fields is performed on personal computers over the Web using an interactive 3D interface based on VRML and Java. The VRML client obtains field information and the surface models of examined objects from a server accessible over the Internet. Various virtual tools enable radiologists and referring physicians to visualize and manipulate complex data sets using a simple interface on low-cost computers.

[Epidemiology of Crohn's disease in the Rijeka-Istra region]. / Epidemiologija Crohnove bolesti na Rijecko-Istarskom podrucju.

The incidence and prevalence of Crohn's disease in Rijeka and Istra, the western part of Croatia with 575,000 inhabitants, were investigated for the period 1973-1994. A total of 197 patients were diagnosed. This gave an annual incidence of 0.34/10(5) in 1973 and 3.47/10(5) in 1994. These data suggest that incidence of Crohn's disease in our region is similar to that reported in northern Europe. The most frequent age groups affected were 15-25 and 50-60 years old. 54% of the patients were younger than 30 years. The small bowel was involved in 49.7% of the patients, the large bowel in 23.3%, and both small and large bowel in 25.8%. At the time of diagnosis 85.8% of patients had abdominal pain, 84.2% diarrhea, 71.6% significant weight loss. All forms of intestinal and extraintestinal complications were observed. Surgery was required in 25.5% patients. No patient developed a malignancy of the gastrointestinal tract. One patient had a cancer of uterus and one a cancer of vulva. The diagnosis was based on clinical features in combination with endoscopic and radiologic findings, and in most patients it was also supplemented by histologic examination. The mean interval from the symptom onset to diagnosis was 1.9 years. The positive family history among relatives was found. In Crohn's disease there was no dose-response relation between smoking and disease. The relationship should be further explored because of the potential for other therapeutic approaches in this disease.

Effects of different growing systems and fertiliser rates on attractiveness of maize crop to beetles of Diabrotica virgifera virgifera LeConte and larvae dammage.

Monitoring of plant lodging, yield reaction due to root injures caused by western corn rootworm larvae (WCR) (Diabroticia virgifera virgifera Le Conte) and adults abundance with yellow Multigard and Pherocone AM and pheromone Csalomon traps, were performed in three field trials. First one with 4 variants of maize growing system; maize continuous cropping, two crop rotation (wheat-maize, soybean-maize) and three crop rotation (wheat-soybean-maize), set up in 1985. Second one with 54 variants, both conducted in Zemun Polje. A large scale trial with three rates of NPK mineral fertilizers; (NPK 0 kg/ha, 170 kg/ha and 270 kg/ha with two type of N applied in side dressing (N 0 kg/ha, 50 kg/ha and 80 kg/ha) was set up in Crepaja in 1997, 1998 and 1999. Each variant of fertilizers had two combinations; one treated with insecticide and another one untreated check. Feeding on root system of WCR larvae, in the variants with insecticide application, resulted in plant lodging that ranged in average from 2.1% in 1997, to 61.6% in 1999, while in variant without insecticide application, root damage resulted in plant lodging from 19.5% in 1997, to 56.6% in 1999. Increasing of the nitrogen rates in the variants without application of insecticide tended to raise the percentage of plant lodging Yield reaction on nitrogen application was positive in 1997, first year and 1998, second year of maize monoculture, while in 1999 was negative. Larval injury affected maize yield in the higher extend in extremely dry year 2000, when yield index was 0.37 comparing 2.86 t/ha in maize monoculture to 7.66 t/ha in three crop rotation, 0.54 (2.86: 5.28 maize monoculture: wheat-maize) and 0.55 (2.86: 5.22 maize monoculture: soybean-maize). Adult abundance monitored with yellow sticky and pheromone traps indicate that maize in three crop rotation has the smallest attraction to the migratory WCR beetles. The choice of three crop rotation seems to be the most promising choice for maize growing, which will result with the lowest risk of plant lodging and yield decrease.

Monte Carlo calculations of lung dose in ORNL phantom for boron neutron capture therapy.

Monte Carlo simulations were performed to evaluate dose for possible treatment of cancers by boron neutron capture therapy (BNCT). The computational model of male Oak Ridge National Laboratory (ORNL) phantom was used to simulate tumours in the lung. Calculations have been performed by means of the MCNP5/X code. In this simulation, two opposite neutron beams were considered, in order to obtain uniform neutron flux distribution inside the lung. The obtained results indicate that the lung cancer could be treated by BNCT under the assumptions of calculations.

Detecting the phase transition in thylakoid membranes of maize inbred lines by means of delayed fluorescence.

In this paper the changes on growth, photosynthesis and water relations were tested by non-invasive fluorescence method. The applications of this method allow to determine some functional properties of prestigious maize inbred lines with erect top leaves. So the temperature dependency of delayed fluorescence intensity maximum of ZPPL 16 is observed at higher temperatures than for ZPPZ 62. This fact correlates with low values of phase transition of activation energy Ea in thylakoid membrane and accompanied by a decrease of the angle and area of the leaf, as well as with the content and the rate of water release from the seed. It seems reasonable to assume that, DF can be applied in breeding and maize hybrid seed production for the estimation of prestigious maize inbred lines and their resistance adaptability to increased and high temperatures, as well as, to drought.

The significance of the ultrasound diagnostics in evaluation of the emboligenic pathogenesis of transient ischemic attacks.

The objective of this study was to examine the possibilities of ultrasound diagnostics in the evaluation of emboligenic pathogenesis of transient ischemic attacks (TIAs) and the frequency of specific origins of embolism. A total of 150 adult patients with TIA and 50 control patients, were examined by neurosonologic, echocardiographic and venous ultrasound examination. Emboligenic pathogenesis of TIA was established in 36.6% of patients. Microembolic signals were detected in 22.7% of the whole group, and 61.8% in emboligenic TIA subgroup. Artery-to-artery embolism from ulcerated plaque of the carotid arteries was found in 12.6% of patients, from the aortic arch atheroma in 3.3% and cardioembolism in 12.6% (atrial fibrillation 7.3%, atrial septal aneurysm 2%, mitral valve prolapse 2%, mechanical heart valve 0.7%, left atrium thrombus 0.7%). Paradoxic embolism with the patent foramen ovale was established in 6% of patients, and with the pulmonary right-to-left shunt in 2%. Correlation with controls showed significantly higher frequency of the ulcerated carotid plaque and frequency of microembolic signals in the TIA group (p < 0.05). The patients with potential sources of embolism had a greater risk of developing TIA than those without these sources.

Vascular risk factors in Alzheimer's disease - preliminary report.

BACKGROUND: The vascular risk factors are associated with an increased risk for vascular cognitive decline (VCD), but also with Alzheimer disease (AD). OBJECTIVE: To investigate vascular risk factors in relation to AD and VCD, with a non-invasive neurosonological methods in a clinical settings. RESULTS: A total of 296 patients with AD and 237 patients with VCD were included in the study. Hypertension, hyperlipidemia, diabetes mellitus, stroke, and white matter changes (p<0.001) were significantly more prevalent in VCD, although they were also present in AD patients. No statistically significant differences were obtained between groups regarding coronary disease, atrial fibrillation, average degree of carotid artery stenosis and carotid intima-media thickness (cITM). However, the patients with AD had carotid artery stenosis ">50%" (p=0.007) and present plaques (p<0.001) more frequently compared to vascular group. The significant associations between robust cognitive measure and vascular factors, diabetes mellitus, carotid stenosis, cITM, and type of plaques were identified only in VCD, but not in AD group. CONCLUSIONS: The vascular risk factors were more prevalent in VCD group, although they were also present in AD. With few treatment options available in AD, it may be important not to neglect the vascular risk factors.

Identification of the global transcriptomic response of the hypothalamic arcuate nucleus to fasting and leptin.

Leptin plays a major role in coordinating the integrated response of the brain to changes in nutritional state. Leptin receptor expressing neurones within the arcuate nucleus (ARC) of the hypothalamus sense circulating leptin and densely innervate other regions of the hypothalamus, including the paraventricular nucleus (PVN). In the ARC, leptin is known to alter the expression of genes with important roles in the control of energy balance, and the aim of the present study was to obtain a more comprehensive picture of the action of leptin in these nuclei. Mice were ad libitum fed, or fasted for 48 h when receiving either sham or i.p. leptin treatment. We used laser capture microdissection and microarrays to identify leptin-regulated transcripts within the ARC. Expression of 639 genes are increased and 452 decreased within the fasted ARC. Leptin regulates 15% and 20% of these genes, respectively. In addition to expected changes in Pomc, Agrp, Npy and Cart, pathway analysis indicated that leptin regulated other genes concerned with energy homeostasis and endocrine function. As previously reported for the PVN, leptin also altered the expression of genes involved in nervous system development and synaptic function. However, aside from a small number of such genes (e.g. Gap43), leptin influenced the expression of different sets of neuronal developmental genes in the ARC and PVN. In conclusion, the present study identifies a set of genes that are regulated, at least in part, by leptin in the ARC, highlighting these as candidates for possible roles in leptin action and resistance.

The effects of neurokinin B upon gonadotrophin release in male rodents.

Growing evidence suggests the tachykinin neurokinin B (NKB) may modulate gonadotrophin secretion and play a role in sex-steroid feedback within the reproductive axis. NKB signalling has recently been identified as being necessary for normal human reproductive function, although the precise mechanisms underpinning this role remain to be established. We have used rodents to explore further the role of NKB within the reproductive axis. In particular, we have studied its interactions with kisspeptin, a neuropeptide essential for reproductive function in rodent and human with close anatomical links to NKB within the hypothalamus. Intraperitoneal administration of NKB (50 nmol) to male mice had no effect on circulating luteinsing hormone (LH) levels and, although i.p. kisspeptin (15 nmol) increased LH five-fold, co-administration of NKB and kisspeptin was indistinguishable from kisspeptin alone. Intracerebroventricular administration of NKB (10 nmol) to male mice also had no effect on LH levels, with 1 nmol kisspeptin i.c.v. significantly increasing LH compared to control (0.37 +/- 0.18 versus 5.11 +/- 0.28 ng/ml, respectively). Interestingly, i.c.v. co-administration of NKB and kisspeptin caused a significant increase in LH concentrations compared to kisspeptin alone (8.96 +/- 1.82 versus 5.11 +/- 0.28 ng/ml respectively). We used hypothalamic explants from rats to assess the effect of NKB on gonadotrpohin-releasing hormone (GnRH) secretion ex vivo. Doses of NKB up to 1000 nm failed to stimulate GnRH secretion, whereas 100 nm kisspeptin robustly increased GnRH secretion. Of note, co-administration of NKB with kisspeptin abrogated the effect of kisspeptin, producing no GnRH release above basal state. Finally, we analysed the expression of Tac2/Tacr3 (genes encoding NKB and NK3R, respectively) within the arcuate nucleus in different nutritional states. After a 48-h fast, the expression of both Tac2 and Tacr3 showed a significant increase, in contrast to levels of Kiss1 and Kiss1r mRNA, which remained unchanged. In male rodent models, NKB and kisspeptin have different effects upon gonadotrophin release and appear to interact in a complex manner.