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Biomedical subjects

R Möller

Publications and source records attributed to R Möller.

At least 19 recordsLinked to original sources
PubMed2005

Peritoneal folds of the rabbit (Oryctolagus cuniculus).

The anatomy of the rabbit is not well known and there is no consensus on the anatomical nomenclature for this species. The objective of this study was to give a complementary description of the peritoneal folds in order to improve the existing knowledge on this species. Eighteen adult rabbits were studied. Ten animals were dissected unfixed and the remaining eight after fixation in formalin. The hepatic ligaments were similar to those of the dog. The transverse mesocolon was absent. The entry to the caudal recess of the omental sac was relatively smaller than that in other domestic species. We consistently found an omental foramen. An amount of fat tissue was almost always found in the proximal mesorchium. The vaginal process was inconstant.

Animals↗
PubMed2004

Android subcutaneous adipose tissue topography in lean and obese women suffering from PCOS: comparison with type 2 diabetic women.

The new optical device, the lipometer, enables the noninvasive, quick, safe, and precise determination of the thickness of subcutaneous adipose tissue (SAT) layers at any given site of the human body. Fifteen anatomically well-defined body sites from neck to calf describe a SAT topography (SAT-Top) like an individual "fingerprint" of a subject. This SAT-Top was examined in 16 women with polycystic ovary syndrome (PCOS) and compared to the body fat distribution of 87 age-matched healthy controls and 20 type-2 diabetic women. SAT-Top differences of these three groups were described and, to render the possibility of visual comparison, the 15-dimensional body fat information was condensed to a two-dimensional factor plot by factor analysis. All PCOS patients had an android body fat distribution with significantly thinner SAT layers on the legs as compared to healthy controls. Moreover, a hierarchical cluster analysis resulted in two distinctly different groups of PCOS women, a lean (PCOSL) and an obese (PCOSO) cluster: compared to healthy women, lean PCOS patients had significantly lower total SAT development, even though height, weight, and body mass index did not deviate significantly. Especially on the legs, their SAT layers were significantly lowered, indicating a more "apple-like" fat distribution type. Obese PCOS women showed a SAT-Top pattern very similar to that of women with type-2 diabetes, although the mean age difference between these groups was more than 30 years. Compared to healthy controls, the SAT-Top of these obese PCOS patients was strongly shifted into the android direction, appearing as "super-apples" with a significantly increased upper trunk obesity to 237.8% and a significantly decreased leg SAT development to 79.8%.

Adipose Tissue↗
PubMed2004

Body fat distribution of overweight females with a history of weight cycling.

Weight cycling may cause a redistribution of body fat to the upper body fat compartments. We investigated the distribution of subcutaneous adipose tissue (SAT) in 30 overweight women with a history of weight-cycling and age-matched controls (167 normal weight and 97 overweight subjects). Measurements of SAT were performed using an optical device, the Lipometer. The SAT topography describes the thicknesses of SAT layers at 15 anatomically well-defined body sites from neck to calf. The overweight women with a history of weight cycling had significantly thicker SAT layers on the upper body compared to the overweight controls, but even thinner SAT layers on their legs than the normal weight women. An android fat pattern was attributed to overweight females and, even more pronounced, to the weight cyclers. The majority of normal weight women showed a gynoid fat pattern. Using stepwise discriminant analysis, 89.0% of all weight cyclers and overweight controls could be classified correctly into the two groups. These findings show the importance of normal weight maintenance as a health-promoting factor.

Adipose Tissue↗
PubMed2003

Subcutaneous adipose tissue pattern in lean and obese women with polycystic ovary syndrome.

The new optical device, Lipometer, permits the noninvasive, quick, safe, and precise measurement of the thickness of subcutaneous adipose tissue (SAT) layers at any given site of the human body. Fifteen anatomically well-defined body sites from neck to calf describe the SAT topography (SAT-Top) like an individual "fingerprint." SAT-Top was examined in 33 women with polycystic ovary syndrome (PCOS), in 87 age-matched healthy controls and in 20 Type-II diabetic women. SAT-Top differences of these three groups were described, and, based on a hierarchical cluster analysis, two distinctly different groups of PCOS women, a lean (PCOS(L)) and an obese (PCOS(O)) cluster, were found. For visual comparison of the different types of body fat distribution, the 15-dimensional body fat information was condensed to a two-dimensional factor plot by factor analysis. For comparison of the PCOS like body fat distribution with the "healthy" fat pattern, the (previously published) SAT-Top results of 590 healthy women and men (20-70 years old) and 162 healthy girls and boys (7-11 years old) were added to the factor plot. PCOS(O) women showed a SAT-Top pattern very similar to that of women with Type-II diabetes, even though the diabetic women were on average 30 years older. Compared with their healthy controls, SAT-Top of these PCOS(O) patients was strongly skewed into the android direction, providing significantly decreased leg SAT development and significantly higher upper body obesity. Compared with healthy women, PCOS(L) patients had significantly lower total SAT development (even though height, weight, and body mass index did not deviate significantly), showing a slightly lowered amount of body fat in the upper region and a highly significant leg SAT reduction. This type of fat pattern is the same as found in girls and boys before developing their sex specific body fat distribution. We conclude that women with PCOS develop an android SAT-Top, but compared in more detail, we found two typical types of body fat distribution: the "childlike" SAT pattern in lean PCOS patients, and the "diabetic" body fat distribution in obese PCOS women.

Adipose Tissue↗
PubMed2001

DNA monolayer on gold substrates characterized by nanoparticle labeling and scanning force microscopy.

Monolayers of single-stranded DNA on gold substrates were studied by scanning force microscopy. Complementary DNA probes labeled by gold nanoparticles were applied for contrast enhancement. Substrate regions modified with DNA could be visualized in a highly specific manner. The influence of the solution concentration on the surface density of adsorbed nanoparticles could be visualized. Because individual label particles can be easily detected, this labeling technique opens the way for characterization of DNA monolayers with a lateral resolution in the nanometer range.

Base Sequence↗
PubMed2001

Do insects use templates or parameters for landmark navigation?

As an explanation for the landmark navigation abilities of insects, the template hypothesis is currently clearly dominating the parameter hypothesis. In a series of computer simulations, this paper investigates the conspicuous behavior of desert ants in experimental setups with expanded landmark arrays. It is shown that a parameter-based model accounts much better for the data than different template models.

Animals↗
PubMed2001

Orthogonal factor coefficient development of subcutaneous adipose tissue topography (SAT-Top) in girls and boys.

The new optical device Lipometer allows noninvasive, quick, and safe determination of the thickness of subcutaneous adipose tissue (SAT) layers (in mm) at any site of the human body. The specification of 15 evenly distributed body sites enables the precise measurement of subcutaneous body fat distribution, so-called subcutaneous adipose tissue topography (SAT-Top). SAT-Top was measured in 980 children aged 7-19 years. In this paper we describe the degree to which SAT-Top body sites are intercorrelated. We consider whether a meaningful reduction of data is possible using factor analysis, which factors can be extracted, and how SAT-Top data of children can be added to a factor value plot, depicting the essential results of age-dependent subcutaneous fat development. SAT layers situated on the same body area provide correlation coefficients up to +r = 0.91. Two factors are extracted: factor 1, containing all upper body sites (from neck to hip); and factor 2, consisting of all leg body sites. When all 980 children are divided into three age groups in a factor value plot, the first age group (7-11 years) shows almost equal SAT-Top development in boys and girls. Afterwards, for the consecutive age groups 2 (11-15 years) and 3 (15-19 years), the age-dependent subcutaneous fat development of boys and girls progresses into nearly orthogonal directions.

Adipose Tissue↗
PubMed2001

Subcutaneous adipose tissue layers as a stable correlate of leptin in response to short term energy restriction in obese girls.

AIMS: We studied the relationship of subcutaneous adipose tissue layers (SAT-layers) measured at 15 specified body sites with leptin before and after a weight loss program for three weeks. SUBJECTS AND METHODS: In 70 obese girls, SAT-layers were measured by means of the optical device, lipometer. Fat mass (FM) was estimated by means of bioelectrical impedance. RESULTS: At the beginning of the study, all estimates of adiposity, insulin, and SAT-layers from the upper body (from 1-neck to 6-lateral chest) were correlated to leptin at a P-value of<0.0001. Percentage FM together with SAT-layer 4-upper back and insulin explained 75% of the variation in leptin (P<0.0001). After three weeks, estimates of adiposity and leptin were reduced (all P<0.0001). Most SAT-layers were reduced, but SAT-layers 8-lower abdomen and 9-lower back were significantly increased. Changes in leptin were best explained by initial leptin, but percentage change (Delta) in insulin, Delta SAT-layer 1-neck, and Delta SAT-layer 3-biceps contributed to the Delta leptin (adj. r(2)=0.47, P<0.0001). In the weight-reduced state, circulating leptin was best explained by three SAT-layers and insulin (adj. r(2)=0.67, P<0.0001). DISCUSSION: The results suggest that Delta changes in leptin are attributable to changes in the endocrine state and subcutaneous fat, and SAT-layers may serve as a stable correlate of leptin in the weight-reduced state.

Adipose Tissue↗
PubMed2001

Interrelationship between estimates of adiposity and body fat distribution with metabolic and hemostatic parameters in obese children.

Adiposity in childhood is often associated with metabolic abnormalities and accompanied by a dysregulation of the coagulation and fibrinolytic systems. We studied the interrelationship of metabolic and hemostatic parameters and explored their relationship with measures of adiposity and fat distribution in obese children. In 34 obese boys (mean age, 11.7 years) and 57 obese girls (12.1 years), blood samples were determined for insulin, glucose, triglycerides, fibrinogen, plasminogen activator inhibitor-1 (PAI-1), and tissue-type plasminogen activator-antigen (tPA-Ag). Body composition was assessed by means of impedance. Waist (Wc) and hip circumference were measured. The thickness of subcutaneous adipose tissue-layers (SAT-layers) was measured at 15 different body sites (from 1-neck to 15-calf) by means of the optical device, Lipometer. Overall subcutaneous fatness (SAT) was calculated and SAT-distribution was estimated by means of factor analysis. Significant correlations were found between different measures of adiposity and Wc with metabolic parameters. Fibrinogen was mainly associated with upper body subcutaneous fatness (factor 1) in boys. In girls, hemostatic parameters were associated with nearly all measures of adiposity and also with factor 1 and SAT. Regression analysis showed that factor 1 together with PAI-1 (both P <.0001) contribute to fibrinogen (adjusted [adj], R(2) =.30). PAI-1 together with trigylcerides (both P <.0001) and age (P <.04) were main determinants for tPA-Ag (adj, R(2) =.41). tPA-Ag (P <.0001) together with glucose (P <.001, negative slope), fibrinogen (P <.001, negative slope), and percentage fat mass (%FM) (P <.01) contributed to PAI-1 (adj, R(2) =.54). These results favor the concept of an interrelationship between metabolic and hemostatic parameters resulting from increased adiposity, perhaps influenced by pubertal development of children. Although upper body subcutaneous fatness was found to be a main correlate of metabolic and hemostatic parameters, it remains to be investigated whether this type of subcutaneous fat distribution is involved in the expression of metabolic and hemostatic risk factors and participates in the dysregulation of the hemostatic system in the state of childhood obesity.

Adipose Tissue↗
PubMed2001

Relationship between subcutaneous fatness and leptin in male athletes.

PURPOSE: Circulating leptin is low in trained subjects and closely related to body fat content. However, data are scarce as to whether differences exist in the relationship between different estimates of adiposity, metabolic parameters, and leptin in endurance- and resistance-trained male athletes. We investigated this relationship with special emphasis on subcutaneous fatness and its distribution. METHODS: 20 endurance (ET) and 17 resistance (RT) athletes recruited from different kind of sports were studied. Fat-free mass (FFM) was estimated by means of impedance and fat mass (FM) was calculated. Subcutaneous fat (SAT) and its distribution was measured by means of the optical device Lipometer at 15 body sites (SAT-layers; from 1-neck to 15-calf) on the right side of the body. Fifteen SAT-layers were summed to calculate SAT. Blood samples were obtained for determination for leptin, insulin, and glucose. Insulin resistance was calculated through the fasting insulin resistance index (FIRI; [insulin x glucose/25]). RESULTS: RT-athletes had a greater body mass and body fat content than ET-athletes, but no differences were found for leptin and metabolic parameters. In all athletes, estimates of adiposity were correlated to leptin. However, in ET-athletes FM (P < 0.05), FFM (P < 0.05), and SAT (P < 0.001) but not metabolic parameters were correlated to leptin. In RT-athletes, SAT (P < 0.0001), metabolic parameters (all P < 0.05), but not FM and FFM were in significant relationship with leptin. Stepwise regression revealed SAT as the main determinant for the variation in leptin in all athletes (adj. R(2 )= 0.52, P < 0.0001). CONCLUSION: The results suggest that estimates of adiposity and metabolic parameters are associated with leptin in a sport-specific manner. Whereas leptin might be regulated by overall subcutaneous fatness in athletes, our study does not imply a main influence of fat patterning on leptin in this group of trained subjects.

Adipose Tissue↗
PubMed2001

Effects of weight loss on leptin, sex hormones, and measures of adiposity in obese children.

Adipose tissue influences steroid conversion by paracrine and autocrine mechanisms. Leptin is secreted by adipocytes and influenced by sex hormones and adiposity. Short-term weight loss in the treatment of childhood obesity reduces leptin and adipose tissue. We therefore asked, Do alterations in sex hormones occur owing to weight loss? and can these alterations be explained by changes in fat mass or sc fat and are alterations in sex hormones directly related to the fall in leptin? Twenty obese boys and 40 obese girls were studied before and after 3 wk of low-calorie diet and physical activity. The weight loss program significantly lowered fat mass, abdominal fat distribution, sc fat (all p < 0.0001), leptin, insulin, and estradiol (all p < 0.0001) but not testosterone. Changes in leptin were related to changes in body mass and to changes in fat mass in boys. In girls, changes in leptin were related to changes in sc fatness and also to changes in insulin. In boys, the reduction in sc fat was positively correlated to changes in testosterone (r = 0.54; p < 0.01) and inversely related to the fall in estradiol (r = -0.41; p < 0.05). In girls, changes in testosterone (r = 0.33; p < 0.05) and in estradiol (r = 0.40; p < 0.01) were related to changes in insulin. Stepwise regression showed that initial leptin was the best determinant for the fall in leptin (adjusted R2 = 0.87; p < 0.0001). The results show that alterations in sex hormones are related to changes in certain fat depots in boys whereas in girls changes in insulin might participate in changes in sex hormones. A greater fall in leptin owing to short-term weight loss is not associated with greater alterations in sex hormones and initial leptin is the best determinant to explain the variability in changes in leptin. The possibility of sex differences in changes in sex hormones secondary to the reduction in fatness warrants further study.

Adipose Tissue↗
PubMed2000

DNA probes on chip surfaces studied by scanning force microscopy using specific binding of colloidal gold.

Single-stranded DNA was covalently bound on chip surfaces using two different silanization procedures. The resulting surfaces were characterized by fluorescence and scanning force microscopy using sequence-complementary DNA molecules with labels. Colloidal gold (30 nm) was used as the topographic label. Scanning force microscopy revealed the individual labels on the surface and their distribution. Steps of silane layers or DNA-modified surfaces prepared using an elastomeric mask provided internal controls for comparison of modified with unmodified surfaces.

Base Sequence↗
PubMed2000

Differences of subcutaneous adipose tissue topography in type-2 diabetic (NIDDM) women and healthy controls.

Women suffering from type-2 diabetes mellitus (non-insulin-dependent diabetes mellitus [NIDDM]) have more total body fat and upper body obesity compared with healthy controls. However, the standard measurement methods have disadvantages such as radiological burden, lack of precision, or high time consumption. A new optical device, the Lipometer, enables the noninvasive, quick, and save determination of the thickness of subcutaneous adipose tissue layers at any given site of the human body. The specification of 15 evenly distributed body sites allows the precise measurement of subcutaneous body fat distribution, so-called subcutaneous adipose tissue topography (SAT-Top). SAT-Tops of 20 women with clinically proven NIDDM and 122 healthy controls matched by age group were measured. In this paper, we describe the precise SAT-Top differences of these two groups and present the multidimensional SAT-Top information condensed in a two-dimensional factor plot and in a response plot of an artificial neural network. NIDDM women provide significantly lower leg SAT-Top and significantly higher upper trunk SAT-Top development ("apple"-type) compared with their healthy controls.

Adipose Tissue↗
PubMed2000

Artificial neural networks compared to factor analysis for low-dimensional classification of high-dimensional body fat topography data of healthy and diabetic subjects.

Subcutaneous adipose tissue thickness was measured in 590 healthy subjects at 15 specific body sites by means of the new optical device, lipometer, providing a high-dimensional and partly highly intercorrelated set of data, which had been analyzed by factor analysis previously. N-2-N back-propagation neural networks are able to perform low-dimensional display of high-dimensional data as a special application. We report about the performance of such a 15-2-15 network and compare its results with the output of factor analysis. As test data for verification, measurement values on women with proven diabetes mellitus type II (NIDDM) are used. Surprisingly our 15-2-15 neural network is able to reproduce the classification pattern resulting from factor analysis very precisely. After extracting the network weights the classification of new subjects is even more simple with the neural network as compared with factor analysis. In addition, the network weights are able to cluster highly correlated body sites nicely to different groups, corresponding to different regions of the human body. Thus, the analysis of these weights provides additional information about the structure of the data. Therefore, N-2-N networks seem to be a good alternative method for analyzing high-dimensional data with strong intercorrelation.

Adipose Tissue↗
PubMed2000

Insect visual homing strategies in a robot with analog processing.

The visual homing abilities of insects can be explained by the snapshot hypothesis. It asserts that an animal is guided to a previously visited location by comparing the current view with a snapshot taken at that location. The average landmark vector (ALV) model is a parsimonious navigation model based on the snapshot hypothesis. According to this model, the target location is unambiguously characterized by a signature vector extracted from the snapshot image. This article provides threefold support for the ALV model by synthetic modeling. First, it was shown that a mobile robot using the ALV model returns to the target location with only small position errors. Second, the behavior of the robot resembled the behavior of bees in some experiments. And third, the ALV model was implemented on the robot in analog hardware. This adds validity to the ALV model, since analog electronic circuits share a number of information-processing principles with biological nervous systems; the analog implementation therefore provides suggestions for how visual homing abilities might be implemented in the insect's brain.

Animals↗
PubMed2000

Artificial neural networks as a method to improve the precision of subcutaneous adipose tissue thickness measurements by means of the optical device LIPOMETER.

The LIPOMETER is an optical device for measuring the thickness of a subcutaneous adipose tissue layer. It illuminates the interesting layer, measures the backscattered light signals and from these, it computes absolute values of subcutaneous adipose tissue layer thickness (in mm). Previously, these light pattern values were fitted by nonlinear regression analysis to absolute values provided by computed tomography. Nonlinear regression analysis might provide slight limitations for our problem: a selected curve type cannot be changed afterwards during the application of the measurement device. Artificial neural networks yield a more flexible approach to this fitting problem and might be able to refine the fitting results. In the present paper we compare nonlinear regression analysis with the behaviour of different architectures of multilayer feed forward neural networks trained by error back propagation. Specifically, we are interested whether neural networks are able to yield a better fit of the LIPOMETER light patterns to absolute subcutaneous adipose tissue layer thicknesses than the nonlinear regression techniques. Different architectures of these networks are able to surpass the best result of regression analysis in training and test, providing higher correlation coefficients, regression lines with absolute values obtained from computed tomography closer to the line of identity, decreased sums of absolute and squared deviations, and higher measurement agreement.

Adult↗
PubMed2000

Increased withdrawal volume per deposit for pre-operative autologous blood donation in adolescents.

OBJECTIVES: This study was undertaken to assess the feasibility, tolerance, haemodynamic and haematologic effects of an aggressive phlebotomy schedule for autologous blood donation (ABD) in adolescents undergoing major orthopaedic surgery. METHODS: Twenty adolescents were studied prospectively; 10 patients in group A donated 20% of the circulating blood volume on 2 occasions, whereas 10 patients in group B donated 10% on 4 occasions. RESULTS: The amount of blood donated, subjective tolerance, cardiovascular changes during the procedure and pre-operative haemoglobin level did not differ between the study groups (group A 111+/-16 vs. group B 106+/-10 g/l). The increase in erythropoietin was greater and occurred sooner in group A than in group B. CONCLUSION: In adolescents ABD is feasible with a reduced number of appointments as they demonstrate tolerance to phlebotomies with a volume which is double the standard per deposit.

Adolescent↗