Altered functional connectivity in common resting-state networks in patients with major depressive disorder: A resting-state functional connectivity study.

The neural correlates of major depressive disorder (MDD) remain disputed. In the absence of reliable biological markers, the dysfunction and interaction of neural networks have been proposed as pathophysiological neural mechanisms in depression. Here, we examined the functional connectivity (FC) of brain networks. 51 healthy volunteers (mean age 33.57 ± 7.80) and 55 individuals diagnosed with MDD (mean age 33.89 ± 11.00) participated by performing a resting-state (rs) fMRI scan. Seed to voxel FC analyses were performed. Compared to healthy control (HC), MDD patients showed higher connectivity between the hippocampus and the anterior cingulate cortex (ACC) and lower connectivity between the insula and the ACC. The MDD group displayed lower connectivity between the inferior parietal lobule (IPL) and the superior frontal gyrus (SFG). The current data replicate previous findings regarding the cortico-limbic network (hippocampus - ACC connection) and the salience network (insula - ACC connection) and provide novel insight into altered rsFC in MDD, in particular involving the hippocampus - ACC and the insula - ACC connection. Furthermore, altered connectivity between the IPL and SFG indicates that the processing in higher cognitive processes such as attention and working memory is affected in MDD. These data further support dysfunctional neuronal networks as an interesting pathophysiological marker in depression.

[Visual analysis for an early detection of diabetic neuropathy]. / Visuelle Analyse zur Früherkennung einer diabetischen Neuropathie.

Diabetic neuropathy is the most common long-term complication of diabetes mellitus. It comes along with significant nerve dysfunction, which is not reversible. Hence, it is essential to detect nerve fibre abnormalities as early as possible. In this paper, we investigate markers describing degradation of corneal nerves. We apply statistical computations and visual analysis to identify those variables of two clinical studies that separate DN patients from a control group. In this way, the diagnosis of DN patients is supported. The visual analysis is based on different representations visualizing both the statistical results and the gathered multi-variate data. The user can interactively manipulate the views, or select data that will be shown by further displays. In this way, the understanding of the data and its classification is supported. Ambiguous categorisations can be identified and grouped into a so-called "fuzzy group". For this group, further investigations are needed to decide about diabetic neuropathy.

[Large-scale imaging of corneal nerve fibres by guided eye movements]. / Großflächige Abbildung kornealer Nervenfasern durch geführte Augenbewegungen.

BACKGROUND: The high resolution of corneal confocal microscopy (CCM) allows in vivo imaging of the corneal sub-basal nerve plexus (SNP). The field of view of a single CCM image (0.16 mm²) is not sufficient for the reliable morphometric characterisation of the SNP. Therefore we are developing a highly automated mosaicking technique for large-area imaging of the SNP using CCM image sequences. METHODS: In order to acquire an image sequence of a larger area of the SNP, the view direction of the patient is guided by a computer-controlled moving fixation target on a display in front of the non-examined eye. The CCM image sequence is recorded with 30 fps. An online calculated mosaic image allows the medical operator to observe the acquisition process and assess the quality and size of the resulting image during the CCM recording process. Remaining image artefacts are corrected in an automated post-processing step. RESULTS: Using a first prototype system and an appropriate fixation target trajectory, a mean growth of the covered SNP area of 0.18 mm²/s could be achieved. CONCLUSION: Using the presented technology, large-area images of the SNP can be generated. The technology is characterized by a high degree of automation and short examination times.

[Quantitative analysis of corneal subbasal nerve plexus with in vivo confocal laser scanning microscopy]. / Quantitative Analyse des subbasalen Nervenplexus der Kornea mittels in vivo konfokaler Laser-Scanning-Mikroskopie.

BACKGROUND: An analysis of the corneal subbasal nerve plexus (SNP) allows an evaluation of the peripheral neuropathy in cases of degenerative diseases. In order to study the SNP structures quantitatively the automatically calculated morphological and topological parameters are required. METHODS: In vivo confocal laser scanning microscopy (Heidelberg Retina Tomograph II/Rostock Cornea Module) was performed in healthy volunteers as well as patients with severe diabetic neuropathy. An adapted image processing algorithm was used to preprocess, segment and evaluate quantitatively the nerve fibers of the SNP. Data sets were analysed statistically. RESULTS: The developed algorithm allows an automated detection of SNP structures. Furthermore, it allows the collection of data based on morphological and topological parameters. The main parameters that show significant differences between healthy cornea and cases of diabetic neuropathy are nerve fibre density and length, number of branching, tortuosity and number of terminal and crossing points. All parameters of the measurements can be used isolated, combined or weighted for quantification of the SNP networks. CONCLUSION: The presented fully automated preprocessing eliminates a large number of motion-induced artefacts. The quality of the resulting pictures allows an automated quantification using characteristic measurements. This represents an in vivo, non-invasive technology analysing degenerative changes of SNP especially in the course of diabetes mellitus.

Studies on water transport through the sweet cherry fruit surface: II. Conductance of the cuticle in relation to fruit development.

Water conductance of the cuticular membrane (CM) of sweet cherry (Prunus avium L. cv. Sam) fruit during stages II and III (31-78 days after full bloom, DAFB) was investigated by gravimetrically monitoring water loss through segments of the exocarp. Segments were mounted in stainless-steel diffusion cells, filled with 0.5 ml of deionized water and incubated for 8 h at 25 +/- 2 degrees C over dry silica. Conductance was calculated by dividing the amount of water transpired per unit surface area and time by the difference in water vapor concentration across the segment (23.07 g m(-3) at 25 degrees C). Fruit mass and fruit surface area increased 4.9- and 2.8-fold between 31 and 78 DAFB, respectively. However, CM mass per unit area decreased from 3.9 to 1.5 g m(-2) and percentage of total wax content remained constant at about 31%. Stomatal density decreased from 0.8 to 0.2 mm(-2) (31-78 DAFB). Total conductance of the CM on the fruit cheek (gtot.) remained constant during stage II of development (approx. 1.38 x 10(-4) m s(-1) from 31 to 37 DAFB), increased to 1.73 x 10(-4) m s(-1) during early stage III of fruit growth (43-64 DAFB) then decreased to 0.95 x 10(-4) m s(-1) at maturity (78 DAFB). Partitioning gtot. into cuticular (gcut.) and stomatal conductance (gsto.) revealed that the relative contribution of gcut. to gtot. increased linearly from 30% to 87% of gtot. between 31 and 78 DAFB. respectively. On a whole-fruit basis, g,tot. and gcut. consistently increased up to 64 DAFB, and decreased thereafter. A significant negative linear relationship was obtained between gcut. and CM thickness, but not between the permeability coefficient (p) and CM thickness. Further, p was positively related to strain rate, suggesting that strain associated with expansion of the fruit surface increased p.

Studies on water transport through the sweet cherry fruit surface: characterizing conductance of the cuticular membrane using pericarp segments.

Water conductance of the cuticular membrane (CM) of mature sweet cherry fruit (Prunus avium L. cv. Sam) was investigated by monitoring water loss from segments of the outer pericarp excised from the cheek of the fruit. Segments consisted of epidermis, hypodermis and several cell layers of the mesocarp. Segments were mounted in stainless-steel diffusion cells with the mesocarp surface in contact with water, while the outer cuticular surface was exposed to dry silica (22 +/- 1 degrees C). Conductance was calculated by dividing the amount of water transpired per unit area and time by the difference in water vapour concentration across the segment. Conductance values had a log normal distribution with a median of 1.15 x 10(-4) m s(-1) (n=357). Transpiration increased linearly with time. Conductance remained constant and was not affected by metabolic inhibitors (1 mM NaN3 or 0.1 mM carbonylcyanide m-chlorophenylhydrazone) or thickness of segments (range 0.8-2.8 mm). Storing fruit (up to 42 d, 1 degrees C) used as a source of segments had no consistent effect on conductance. Conductance of the CM increased from cheek (1.16 +/- 0.10 x 10(-4) m s(-1)) to ventral suture (1.32 +/- 0.07 x 10(-4) m s(-1)) and to stylar end (2.53 +/- 0.17 x 10(-4) m s(-1)). There was a positive relationship (r2=0.066**; n=108) between conductance and stomatal density. From this relationship the cuticular conductance of a hypothetical astomatous CM was estimated to be 0.97 +/- 0.09 x 10(-4) m s(-1). Removal of epicuticular wax by stripping with cellulose acetate or extracting epicuticular plus cuticular wax by dipping in CHCl3/methanol increased conductance 3.6- and 48.6-fold, respectively. Water fluxes increased with increasing temperature (range 10-39 degrees C) and energies of activation, calculated for the temperature range from 10 to 30 degrees C, were 64.8 +/- 5.8 and 22.2 +/- 5.0 kJ mol(-1) for flux and vapour-concentration-based conductance, respectively.

Human pancreatic secretion and intestinal motility: effects of ileal nutrient perfusion.

To study the effects of intraileal nutrients on human pancreatic secretion and gastrointestinal motility, nine healthy subjects were intubated with an oroileal multilumen tube for ileal perfusion, duodenal juice aspiration, and intestinal motility recording. The duodenum was perfused continuously with essential amino acids to induce submaximal stimulation of pancreatic enzyme secretion and fed motility pattern. Additional ileal perfusion with carbohydrate at quantities similar to those observed under physiological late postprandial conditions or fat at isocaloric loads significantly decreased pancreatic enzyme outputs by greater than 80% (P less than 0.001) compared with saline. Ileal carbohydrate or fat induced a duodenal motor activity front that migrated distally and was followed by reduced motility. In summary, ileal delivery of small quantities of nutrient markedly decreased endogenously stimulated pancreatic enzyme secretion in humans. This was associated with specific changes in fed intestinal motility that converted to patterns characteristic of the interdigestive state. Our findings suggest that the distal small intestine may participate in the late postprandial regulation of gastrointestinal function in humans.