PubMed Health⌕ Search

Biomedical subjects

A Franck

Publications and source records attributed to A Franck.

At least 19 recordsLinked to original sources
PubMed2006

[Aim, content, evaluation and perspectives of surgical training in randomized trials at the Study Centre of the German Surgical Society].

BACKGROUND: Clinical research, especially the management of randomized controlled multicentre trials, is a challenge for surgical investigators. To provide the theoretical background and practical knowledge needed for surgical trials, it is necessary to revise standard training programmes, which focus on pharmacological research. The main differences concern regulatory aspects and content, especially in achieving and maintaining comparability, equal treatment, and outcome assessment using special randomisation techniques and standardised surgical procedures. METHODS: In November 2005, in cooperation with the Coordinating Centre for Clinical Trials in Heidelberg, the Study Centre of the German Surgical Society Study Group (SDGC) hosted a clinical investigation course for surgeons. During 3 days, 24 participants were systematically instructed by 16 lecturers on clinical trials (planning, treatment by protocol, data management, biometrics, ethics, and law), followed by participants' evaluation of the course. RESULTS: On a scale of 1 to 6 (excellent to insufficient, respectively) the mean grades for the course were 1.6 for content, 1.55 for clarity, and 1.55 for learning effect. Partial repetition, lack of work in small groups, and not enough materials to take home were the major criticisms. CONCLUSIONS: The evaluation emphasised the necessity and value of the course. Further courses with continued evaluation are necessary and can be based on the same underlying concept. However, the mere qualification of surgeons as clinical investigators without substantial additional improvements in structural problems and increased financial project support will not fundamentally improve clinical research in Germany.

Attitude of Health Personnel↗
PubMed2006

Concrete floor-bovine claw contact pressures related to floor roughness and deformation of the claw.

The intention of this research was to study the impact of concrete floor surface roughness on a bovine claw model and to assess the deformation of the bovine claw model under load. The pressure distribution between the floor and the claw is the key method in this research. Monitoring foot-to-ground pressure distributions may provide insight into the relation between high local pressures and foot lesions. Concrete floor samples were made with 5 different finishing methods. Their roughness was determined by measuring the heights of the "peaks and the valleys" of the surface with a high-precision laser beam. The smoothest surface was the sample finished with a metal float (surface roughness R(a) = 0.062 mm) and the roughest surface occurred with the heavily sandblasted sample (surface roughness R(a) = 0.488 mm). The roughness of the concrete floor samples was related to the mean and peak contact pressures that can occur in a laboratory test bench between floor and bovine claw. It was found that the claw itself has approximately 2 times more effect on these contact pressures than the surface roughness. Peak pressures found were high enough (up to 111 MPa) to cause damage to the bovine claw sole horn. The strains occurring in the horn wall were measured and related to the floor-finishing method and the load. Strain gauge measurements indicated that it is difficult to predict what kind of deformation of the claw wall will occur at a certain location. Different strains will occur for different floor-finishing methods. The corresponding stresses in the horn wall did not exceed the yield stress (14 and 11 MPa for dorsal and abaxial wall horn, respectively).

Animals↗
PubMed2005

[Guidelines on cardiovascular disease prevention in clinical practice].

These recommandations are largely based on the "European Guidelines on Cardiovascular Disease Prevention in Clinical Practice" proposed by the "Third Joint Task Force of European and other Societies on Cardiovascular Disease Prevention in Clinical Practice". The model used to assess the overall risk was adapted for Belgium. Otherwise, very few things were changed from the Exectutive Summary of the European Guidelines.

Belgium↗
PubMed2005

[Recommendations for the prevention of cardiovascular diseases in clinical practice].

These recommendations are largely based on the Executive Summary of the "European Guidelines on Cardiovascular Disease Prevention in Clinical Practice" proposed by the "Third Joint Task Force of European and other Societies on Cardiovascular Disease Prevention in Clinical Practice". The model used to assess the overall risk was adapted for Belgium. Otherwise, very few things were changed from the Executive Summary of the European Guidelines.

Belgium↗
PubMed2002

Technological functionality of inulin and oligofructose.

Inulin and oligofructose are functional food ingredients which offer a unique combination of nutritional properties and important technological benefits. They are found in many vegetables and fruits and can be industrially obtained from chicory roots. In food formulations, inulin and oligofructose may significantly improve organoleptic characteristics. Their incorporation allows upgrading of both taste and mouthfeel in a wide range of food applications. Oligofructose is highly soluble and possesses technological properties that are closely related to those of sugar and glucose syrups. It is often used in combination with high intensity sweeteners. Inulin has a much lower solubility, improves the stability of foams and emulsions and shows exceptional fat-like characteristics when used under the form of a gel in water. Fat and carbohydrate replacement with chicory inulin and oligofructose offers the advantage of not compromising on taste and texture, while delivering nutritionally enhanced products.

Cichorium intybus↗
PubMed2000

Four dimensional bolus tagging imaging of pulsatile flow.

Inversion bolus tagging MR methods were used to provide a graphic depiction of the axial velocity in three spatial dimensions for pulsatile flow through complex geometries. Visualization of the flow field was readily apparent, and a train of tagged boli were depicted providing an immediate overview of the displacement of flowing fluid over the entire pulsatile cycle. Tagging efficiency obtained using adiabatic inversion pulses was improved compared to that with a windowed sinc pulse. Results from phantom experiments on steady flow were correlated with computational fluid dynamic (CFD) simulations. The use of 3D methods reduced spatial partial volume effects, and the displacement of boli in a steady flow experiment correlated well with CFD simulations. The use of adiabatic inversion pulses resulted in sharp edged inversion regions with good retention of longitudinal magnetization. However in order to keep the pulse duration short, of the order of 2-5 ms, a rather large RF amplitude had to be used. The inversion bolus tagging method is useful in visualizing the flow field in multiple levels for pulsatile fluid flowing through complex geometries, and may be useful in fluid dynamic applications.

Blood Flow Velocity↗
PubMed1999

Functional food properties of non-digestible oligosaccharides: a consensus report from the ENDO project (DGXII AIRII-CT94-1095).

This paper results from the final phase of the ENDO project (DGXII AIRII-CT94-1095), a European Commission-funded project on non-digestible oligosaccharides (NDO). All participants in the programme met to perform a consensus exercise on the possible functional food properties of NDO. Topics studied during the project (including a workshop on probiotics and prebiotics) and related aspects, for which considerable evidence has been generated recently, were evaluated on the basis of existing published scientific evidence. There was a general consensus that: (1) there is strong evidence for a prebiotic effect of NDO in human subjects. A prebiotic effect was defined as a food-induced increase in numbers and/or activity predominantly of bifidobacteria and lactic acid bacteria in the human large intestine; (2) there is strong evidence for the impact that NDO have on bowel habit; (3) there is promising evidence that consumption of inulin-type fructans may result in increased Ca absorption in man; (4) there are preliminary indications that inulin-type fructans interact with the functioning of lipid metabolism; (5) there is preliminary evidence in experimental animals of a preventive effect against colon cancer. Human nutrition studies are needed to substantiate these findings. It was concluded that the nutritional properties of NDO may prove to be a key issue in nutritional research in the future.

Animals↗
PubMed1998

Functional food science and gastrointestinal physiology and function.

The gut is an obvious target for the development of functional foods, acting as it does as the interface between diet and the metabolic events which sustain life. The key processes in digestive physiology which can be regulated by modifying diet are satiety, the rate and extent of macronutrient breakdown and absorption from the small bowel, sterol metabolism, the colonic microflora, fermentation, mucosal function and bowel habit, and the gut immune system. The intestinal microflora is the main focus of many current functional foods. Probiotics are foods which contain live bacteria which are beneficial to health whilst prebiotics, such as certain non-digestible oligosaccharides which selectively stimulate the growth of bifidobacteria in the colon, are already on the market. Their claimed benefits are to alleviate lactose maldigestion, increase resistance to invasion by pathogenic species of bacteria in the gut, stimulate the immune system and possibly protect against cancer. There are very few reports of well-designed human intervention studies with prebiotics as yet. Certain probiotic species have been shown to shorten the duration of rotavirus diarrhoea in children but much more work is needed on the mechanism of immunomodulation and of competitive exclusion and microflora modification. The development of functional foods for the gut is in its infancy and will be successful only if more fundamental research is done on digestive physiology, the gut microflora, immune system and mucosal function.

Bacteria↗
PubMed1997

Organically modified aluminosilicate mesostructures from block copolymer phases

Organically modified aluminosilicate mesostructures were synthesized from two metal alkoxides with the use of poly(isoprene-b-ethyleneoxide) block copolymers (PI-b-PEO) as the structure-directing molecules. By increasing the fraction of the inorganic precursors with respect to the polymer, morphologies expected from the phase diagrams of diblock copolymers were obtained. The length scale of the microstructures and the state of alignment were varied using concepts known from the study of block copolymers. These results suggest that the use of higher molecular weight block copolymer mesophases instead of conventional low-molecular weight surfactants may provide a simple, easily controlled pathway for the preparation of various silica-type mesostructures that extends the accessible length scale of these structures by about an order of magnitude.

Journal Article↗
PubMed1997

Human uterine smooth muscle exhibits a very low phosphocreatine/ATP ratio as assessed by in vitro and in vivo measurements.

The purpose of the study was to investigate by in vitro and in vivo methods the phosphocreatine (PCr)/ ATP ratio as an expression of the energy metabolic state of human myometrium in comparison with striated skeletal muscle. The contents of PCr and adenylates in biopsies of uterine smooth muscle and m. rectus abdominis from seven term pregnant women were determined in vitro and compared with results obtained in vivo by phosphorus magnetic resonance spectroscopy (31P-MRS) in the uterus and m. gastrocnemius of eight non-pregnant women. The PCr/ATP ratio in the striated skeletal muscle was about three times higher than that of the myometrium. The results of the in vitro biopsy part of the study and the in vivo 31P-MRS part conformed with each other. In the biopsies both PCr and ATP concentrations were significantly lower in the myometrium than in the rectus muscle, but the difference for PCr was more pronounced, accounting for the significantly lower PCr/ATP ratio in the uterine smooth muscle. The energy metabolic pattern of uterine smooth muscle differs from that of striated skeletal muscle regarding the contents of high-energy phosphocompounds and the PCr/ATP ratio. This in vivo finding is the first report on human smooth muscle using 31P-MRS.

Adenosine Diphosphate↗
PubMed1997

Alexithymia in patients with eating disorders: an investigation using a new projective technique.

The concept of alexithymia was scrutinized in a group of female patients with eating disorders: 15 anorectics and 13 bulimics (mean age of 27 yr.), plus a control group of 21 (mean age 38 yr.). Subjects were interviewed and tested. In the main test an ambiguous face was flashed briefly on a screen opposite the viewer who had to describe her impressions. To enhance the ego-involvement, subliminal words (I, I ILL, I WELL) were presented before each exposure. Contrary to expectations the present patients used more emotional words than controls. Instead, they employed alternative strategies to avoid empathizing. The results were interpreted as indicating a pronounced incapacity for emotional understanding.

Adult↗
PubMed1993

A theoretical study of amplitude modulation and time shifting in quantitative MR measurements of motion in brain tissue.

MR imaging pulse sequences can be made sensitive to motion by adding gradients with different strengths at different time intervals. In the well-known phase mapping method, such velocity encoding gradients are used to obtain phase information linear to the velocity of the studied object in the direction of the gradient. When very low velocities are studied, a long duration velocity-encoded gradient is required to obtain sufficient velocity sensitivity. In such cases, variation in the object velocity during the execution of the sequence may hamper the accuracy of the method. In this study, we have made a computer simulation of the performance of a phase mapping method sequence (TE = 46 msec) designed for quantitative studies of motion in brain tissue. Using a Gaussian-shaped velocity input function, the time shifting and the amplitude modulation properties of the sequence was studied for various values of the duration, defined as the full width of tenth of maximum (FWTM), of the input function. The time shift corresponded well to the center of the 180 degrees RF pulse, and the amplitude modulation was seen to decrease with increasing time duration of the velocity input function. Applied on in vivo data, where an approximately gaussian-shaped brain motion velocity pattern was assumed to have a duration of 150 msec, the amplitude modulation of the sequence was estimated to 2%.

Brain↗
PubMed1993

Vascular dementia in the Lundby study. 2. An attempt to identify possible risk factors.

Vascular dementia represents a group of diseases of great medical and social impact. Its etiology is largely unknown but is most likely multifactorial. Factors related to the brain circulation are involved. The aim of the present study was to find out if personality and social background factors might have a clear precipitating or protective value. This study comprises a total population of 2,612 individuals from a geographically delimited area, Lundby, in southern Sweden. In 1957, Hagnell personally examined 99% of the population. A follow-up study of the same individuals, irrespective of domicile, was performed 15 years later. No social background factors proved to be relevant in this study. Personality factors, including psychosomatic reactions, did, however, demonstrate a highly predictive influence on the risk of developing vascular dementia.

Cohort Studies↗
PubMed1993

On the pulsatile nature of intracranial and spinal CSF-circulation demonstrated by MR imaging.

Cerebrospinal fluid (CSF) flow was studied in 24 healthy volunteers using gated MR phase imaging. The subarachnoid space (SAS) was divided into 5 compartments depending on the magnitude of the pulsatile CSF flows: a high velocity compartment in the area of the brain stem and spinal cord, 2 slow ones at the upper and lower extremes of the SAS, and finally 2 intermediate velocity compartments in between. The main pulsatile spinal flow channel had a meandering pattern. The extraventricular CSF-circulation can be explained by pulsatile CSF flow without the necessity of assuming existence of a net flow. A successive time offset during the cardiac cycle has been found in the fronto-occipital direction of the interplay between the arterial expansion, brain expansion, volume changes of the CSF spaces and of the veins. It is proposed to name this time offset the intracranial "volume wave" (VoW).

Adult↗
PubMed1993

Target delineation in radiosurgery for cerebral arteriovenous malformations. Assessment of the value of stereotaxic MR imaging and MR angiography.

A study of 6 selected arteriovenous malformation (AVM) patients was performed to investigate the feasibility of delineating an AVM on MR images and to compare the AVM volume outlined on different images. Conventional stereotaxic angiograms, stereotaxic MR images and MR angiograms using several different pulse sequences were obtained prior to radiosurgery. Treatment plans were made from the conventional stereotaxic angiograms. These plans were then transferred to a separate dose planning computer which displayed the MR images with the superimposed isodose lines. The radiated volumes of AVM and brain tissue were measured from these MR images. Last, an assessment was made of the radiation volume needed for an appropriate treatment of the AVM if the treatment plan was made from the MR images rather than from the conventional stereotaxic angiogram. It was possible to delineate medium and large size AVM nidi on stereotaxic MR images based on an integration of information obtained from various pulse sequences. The estimated volumes of the AVM nidi were found to be larger on the conventional stereotaxic angiograms than on the stereotaxic MR images. Consequently, a dose plan based on a conventional stereotaxic angiogram would result in a higher integral dose to the brain with the same target dose. By using reliable MR information it is expected that the volume of brain exposed to radiation could be decreased and the adverse effects of stereotactic radiosurgery for AVM thereby minimized.

Adult↗
PubMed1992

Pulsatile brain movement and associated hydrodynamics studied by magnetic resonance phase imaging. The Monro-Kellie doctrine revisited.

Brain tissue movements were studied in axial, sagittal and coronal planes in 15 healthy volunteers, using a gated spin echo MRI sequence. All movements had characteristics different from those of perfusion and diffusion. The highest velocities occurred during systole in the basal ganglia (maximum 1.0 mm/s) and brain stem (maximum 1.5 mm/s). The movements were directed caudally, medially and posteriorly in the basal ganglia, and caudally-anteriorly in the pons. Caudad and anterior motion increased towards the foramen magnum and towards the midline. The resultant movement occurred in a funnel-shaped fashion as if the brain were pulled by the spinal cord. This may be explained by venting of brain and cerebrospinal fluid (CSF) through the tentorial notch and foramen magnum. The intracranial volume is assumed to be always constant by the Monro-Kellie doctrine. The intracranial dynamics can be viewed as an interplay between the spatial requirements of four main components: arterial blood, capillary blood (brain volume), venous blood and CSF. These components could be characterized, and the expansion of the arteries and the brain differentiated, by applying the Monro-Kellie doctrine to every moment of the cardiac cycle. The arterial expansion causes a re-moulding of the brain that enables its piston-like action. The arterial expansion creates the prerequisites for the expansion of the brain by venting CSF to the spinal canal. The expansion of the brain is, in turn, responsible for compression of the ventricular system and hence for the intraventricular flow of CSF.

Adult↗
PubMed1992

Senile dementia of the Alzheimer type in the Lundby Study. II. An attempt to identify possible risk factors.

In recent years research on senile dementia of the Alzheimer type (SDAT) has made progress within the field of pathology and to a certain extent in that of heredity. Within epidemiology, the search for risk factors is intensifying but the findings are still inconclusive. The present study of possible risk factors concentrates on environmental and personality factors. The total population of 2612 persons from a geographically delimited area, Lundby, two neighbouring parishes in southern Sweden, was examined in 1957 by one psychiatrist (Hagnell). A follow-up study of the same population, irrespective of domicile, was performed 15 years later, in 1972. Various precipitating as well as protective personality background factors were found to be significant for the outcome of SDAT, but no environmental factors appeared to be statistically significant in this cohort.

Aged↗