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R Eggers

Publications and source records attributed to R Eggers.

At least 19 recordsLinked to original sources
PubMed2003

Adsorption kinetics of surfactant mixtures from micellar solutions as studied by maximum bubble pressure technique.

The adsorption kinetics of micellar solutions of anionic/cationic SDS/DATB mixtures with mixing ratios of 10/1 and 10/2, respectively, are studied experimentally by means of the maximum bubble pressure method. For long adsorption times the adsorption of the highly surface-active anionic/cationic complex leads to a decrease of dynamic surface tension in comparison to the single SDS system. However, the situation is the reverse for short adsorption times where the dynamic surface tension is increased by addition of the cationic surfactant, although the overall concentration is increased. This unexpected behavior is explained by partial solubilization of free SDS molecules into micelles formed by SDS/DTAB complexes. With increasing overall concentration, when eventually the CMC of SDS is reached, the anionic/cationic complex itself is solubilized by SDS micelles. Finally, no complex micelles, which for their part can solubilize an excess of SDS molecules, are present. Hence, the dynamic properties of the solution are no longer influenced by the depletion of SDS molecules and the mixture tends to behave like a pure SDS solution.

Journal Article↗
PubMed2002

Effects of short-term treatment with diclofenac-colestyramine on renal function and urinary prostanoid excretion in patients with type-2 diabetes.

OBJECTIVE: To determine the effect of short-term administration of diclofenac-colestyramine on glomerular filtration rate (GFR), renal plasma flow (RPF) and urinary excretion of prostanoids in patients with type-2 diabetes without and with impaired renal function. METHODS: In the randomised, single-blind, placebo-controlled, two-period crossover study, 32 patients with type-2 diabetes (group 1: 16 patients without impaired renal function, creatinine clearance > or =80 ml/min and group 2: 16 patients with impaired renal function, creatinine clearance 30-79 ml/min) received 140 mg diclofenac-colestyramine (corresponding to 75 mg diclofenac sodium) or placebo twice a day on days 1 and 2 and once on day 3 with a wash-out period of 6 days between the two periods. GFR was assessed using both measurement of creatinine clearance and calculation of inulin clearance and RPF was assessed using calculation of para-aminohippurate (PAH) clearance after the short-term administration on day 3. Urinary excretion of prostanoids (PGE(2), PGE-M, 6-keto-PGF(1alpha), 2,3-dinor-6-keto-PGF(1alpha), TxB(2), 2,3-dinor-TxB(2) and 11-dehydro-TxB(2)) were measured before and after drug intake. RESULTS: Comparison with placebo showed no effect of diclofenac-colestyramine on creatinine, inulin or PAH clearance ( P>0.05) in patients with type-2 diabetes either without or with impaired renal function. The differences in creatinine, inulin and PAH clearance between the two groups of patients were not influenced by diclofenac-colestyramine. Urinary excretion of PGE(2), PGE-M, 6-keto-PGF(1alpha), 2,3-dinor-6-keto-PGF(1alpha), TxB(2), 2,3-dinor-TxB(2) ( P=1.89) and 11-dehydro-TxB(2) was significantly reduced by diclofenac-colestyramine. CONCLUSION: These results indicate that proven non-specific cyclooxygenase inhibition by short-term administration of diclofenac-colestyramine did not affect renal haemodynamic function (GFR, RPF) in patients with type-2 diabetes either without or with impaired renal function.

Aged↗
PubMed2002

Intravitreal injection of adeno-associated viral vectors results in the transduction of different types of retinal neurons in neonatal and adult rats: a comparison with lentiviral vectors.

Replication-deficient viral vectors encoding the marker gene green fluorescent protein (GFP) were injected into the vitreous of newborn, juvenile (P14), and adult rats. We tested two different types of modified virus: adeno-associated viral-2-GFP (AAV-GFP) and lentiviral-GFP vectors (LV-GFP). The extent of retinal cell transduction in different-aged animals was compared 7, 21, and 70 days after eye injections. At all postinjection times, LV-GFP transduction was mostly limited to pigment epithelium and cells in sclera and choroid. In contrast, transduction of large numbers of neural retinal cells was seen 21 and 70 days after AAV-GFP injections. AAV-GFP predominantly transduced neurons, although GFP-positive Müller cells were seen. All neuronal classes were labeled, but the extent of transduction for a given class varied depending on injection age. After P0 injections about 50% of transduced cells were photoreceptors and 30-40% were amacrine or bipolar cells. After adult injections 60-70% of transduced cells were retinal ganglion cells. In adults many GFP-positive retinal axons were traced through the optic nerve/tract and terminal arbors were visualized in central targets.

Adenoviridae↗
PubMed2002

Oligoneuronal hypoganglionosis in patients with idiopathic slow-transit constipation.

PURPOSE: Several alterations of the enteric nervous system have been described as an underlying neuropathologic correlate in patients with idiopathic slow-transit constipation. To obtain comprehensive data on the structural components of the intramural nerve plexus, the colonic enteric nervous system was investigated in patients with slow-transit constipation and compared with controls by means of a quantitative morphometric analysis. METHODS: Resected specimens were obtained from ten patients with slow-transit constipation and ten controls (nonobstructive neoplasias) and processed for immunohistochemistry with the neuronal marker Protein Gene Product 9.5. The morphometric analysis was performed separately for the myenteric plexus and submucous plexus compartments and included the quantification of ganglia, neurons, glial cells, and nerve fibers. RESULTS: In patients with slow-transit constipation, the total ganglionic area and neuronal number per intestinal length as well as the mean neuron count per ganglion were significantly decreased within the myenteric plexus and external submucous plexus. The ratio of glial cells to neurons was significantly increased in myenteric ganglia but not in submucous ganglia. On statistical analysis, the histopathologic criteria (submucous giant ganglia and hypertrophic nerve fibers) of intestinal neuronal dysplasia previously described in patients with slow-transit constipation were not completely fulfilled. CONCLUSION: The colonic motor dysfunction in slow-transit constipation is associated with quantitative alterations of the enteric nervous system. The underlying defect is characterized morphologically by oligoneuronal hypoganglionosis. Because the neuropathologic alterations primarily affect the myenteric plexus and external submucous plexus, superficial submucous biopsies are not suitable to detect these innervational disorders.

Adult↗
PubMed2002

Expression of neural cell adhesion molecule (NCAM) in the peripheral nerve fibers demonstrated by postembedding immunogold method on ultrathin sections. A preliminary study.

The neural cell adhesion molecule, NCAM, is thought to be necessary for the interaction between neurons, axons and glial cells, axons and target structures, and for myelination. The NCAM localization in the peripheral nerves has been less well studied. The data have shown significant differences. In this study, the distribution of the NCAM immunoreactivity in the sciatic nerves of 10- and 15-day-old Wistar rats was examined on ultrathin sections by the immunogold postembedding method. The sections were immunotested with a polyclonal antibody (Santa Cruz Biotechnology) that recognizes rat NCAM. The antibody was visualized with donkey anti-goat IgG, conjugated to 6 nm colloidal gold. NCAM immuno-like activity was found on axoplasmic profiles of myelinated and nonmyelinated axons, at non-assembled myelin lamellae, and at axo-glial junctions of the paranodes. The compact myelin and the Schwann cell cytoplasm were immunonegative. The presence of some NCAM immunoactivity on the level of the noncompact myelin membranes, deprived of the major myelin protein Po, might be associated with the mechanism of their maintenance.

Aging↗
PubMed2001

DNA microarrays based on noncovalent oligonucleotide attachment and hybridization in two dimensions.

Short oligonucleotide probes have been linked to a solid support by simple electrostatic adsorption onto a positively charged surface film. Attachment was obtained by microfluidic application of unmodified oligonucleotides in distilled water onto amino-silanized glass. It has been demonstrated that an extremely stable monolayer of oligonucleotide is obtained by this method, at a density of about 10(11) molecules/mm(2), which approaches the limit expected for a two-dimensional closest-packed array. Application of oligonucleotide by adsorption is followed by capping with acetic anhydride in the vapor phase, and then capping with succinic anhydride in solution to form a surface with weak negative charge. The capping method has been successfully employed for microarray fabrication and for the analysis of single nucleotide polymorphisms in the k-ras gene. The data reveal that, subsequent to capping, the adsorptive association of oligonucleotide to the surface yields a probe layer which is capable of single nucleotide base mismatch discrimination and high apparent binding affinity.

Acetic Anhydrides↗
PubMed2001

Immunohistochemical localization of the neural cell adhesion molecule in the rat sciatic nerve.

The neural cell adhesion molecule (NCAM) has been widely studied in the early embryonal development of the nervous system. The data about NCAM distribution in the peripheral nerves during postnatal life are scant and some controversial. In the present study, the NCAM localization in the sciatic nerves of 15-day-old Wistar rats has been studied. Semi-thin sections of the nerves were immunotested with a polyclonal antibody (Santa Cruz Biotechnology) that recognizes rat NCAM. The antibody was visualized with donkey anti-goat IgG, conjugated to 12 nm colloidal gold, and silver amplification. In the myelinated nerve fibres, the immunoreactivity was associated with the axons, mainly with their plasma membrane, which was unstained in the nodes of Ranvier. The myelin sheaths and the myelinating Schwann cells were negative. The extracellular matrix and the bundles of non-myelinated nerve fibres were immunopositive.

Animals↗
PubMed2001

N- and R-cadherins expression in the rat sciatic nerve demonstrated by postembedding immunogold method on semi-thin sections.

The calcium-dependent adhesion molecules N- and R-cadherins take part in the morphogenesis of the nervous system. The data about their localization in the peripheral nerves postnatum are limited and somewhat controversial. In the present study, a new methodological approach to the immunohistochemical cadherin detection has been applied. The sciatic nerves of 10-day-old rats were immunotested on semi-thin Epon sections by anti-N- and R-cadherins polyclonal antibody and visualized by IgG conjugated to colloidal gold and silver amplification. In the myelinated nerve fibers, an immuno-like activity was associated with the axoplasm and axolemma, the surface of the myelinating Schwann cells and their extracellular matrix. The units of nonmyelinated fibres and their associated glial cells were also intensely immunostained. The myelin sheaths and the glial cytoplasm were immunonegative. The significance of the localization is discussed in regard to the possible role of N- and R-cadherins in the anatomical and functional compartmentation of peripheral nerves.

Animals↗
PubMed2000

Automatic image analysis of the postnatal growth of axons and myelin sheaths in the tibial and peroneal nerves of the rabbit.

The numerous morphometric studies on the myelinated fibers in the peripheral nerves have presented varying results. Only a few studies deal with the peripheral nerves from rabbits. In this work, a morphometric study was carried out on the tibial and peroneal nerves of new-born, 10-, 15-, 20-, 30-, 60-, 90- and 240-day-old rabbits. The bilateral proximal segments of both nerves were investigated. Negatives of semi-thin cross sections were used for myelinated fiber morphometric analysis, carried out by an OLYMPUS Video image analyser. Two morphometric parameters, the average axon diameter (AD) (the average length of Feret's diameters) and the specific width of the myelin sheaths (SWMS) (specifying the total width of the myelin sheath), were evaluated for every age group. In the tibial and peroneal nerves a bimodal distribution of the average AD appeared on the 20th day, and of the SWMS on the 10th day postnatum. A tight correlation was obtained when comparing mean AD (mAD) and mean SWMS (mSWMS) in new-born and 240-day-old rabbits. From birth to adulthood the mAD increased in both nerves by about 270% and the mSWMS by about 280%. The mAD/mSWMS ratio in both new-born and 8-month-old rabbits was found to be 4 in the tibial and 5 in the peroneal nerves. According to the available data, an approach to the measurement of AD as an average length of Feret's diameters and the measurement of the myelin thickness as a SWMS has not yet been employed. An extension of this methodological approach could help to understand the growth and myelinization of peripheral nerve fibers.

Animals↗
PubMed2000

Topologic distribution of different types of neurons in the human putamen.

OBJECTIVE: To test the assumption that the various types of neuron in the human putamen appear to be randomly distributed and to quantify the way in which they are arranged, stochastic geometry, multivariate analysis and the interactive evaluation technique were employed. STUDY DESIGN: Twenty-seven human putamina without demonstrable signs of neurologic change were dissected out, fixed in 4% formalin and embedded in paraffin. The 20-micron paraffin sections were stained in an aldehyde-fuchsin and cresyl-violet solution, which makes it possible to distinguish between seven different neuron populations in the putamen. The gravity centers, size and form factors of these neurons were determined morphometrically under a light microscope. The data obtained were used to calculate the spatial distribution of the neurons by interactive and structure analytical methods. RESULTS: Visual point field analysis revealed an irregular arrangement of the different types of neurons. Point process analysis detected a significant hard core process of type 1 and a cluster process of type 6 neurons. With nearest neighborhood analysis, significant differences were found between certain populations of neurons and Poisson processes. Comparison of the results of multivariate cluster analysis with the investigator-dependent results of visual point field analysis showed clear differences. CONCLUSION: By means of structure analytical methods, the arrangement of different populations of neurons can be demonstrated. Some neuronal distributions are detectable only by using one of these techniques. The question of random or nonrandom distribution of the neurons in the human putamen can now be answered definitively: arrangement of the different populations of neurons is structured.

Adult↗
PubMed1999

Flat-bed scanning as a tool for quantitative neuroimaging.

The aim of this study was to compare three different imaging techniques which are used to provide data on the laminar structure of the human cerebral cortex. Region V1 of Brodmann's area 17 stained with cresyl violet was investigated, and a conventional semi-automatic morphometric evaluation, the videomicroscropic procedure and a new transparent flat-bed scanning technique were compared. The results of each digitizing method were converted into normalized profiles which allow the laminae in the striate cortex to be displayed. It was found that major laminar patterns can be detected by the scanning technique, but that subsidiary laminations are more clearly displayed by morphometry and videomicroscopy. For magnifications up to x 400 a high resolution transparent flat-bed scanner may be used in place of the videomicroscopy technique.

Aged↗
PubMed1999

[Disorders of intestinal innervation as a possible cause for chronic constipation].

The gastrointestinal tract contains the largest amount of nerve cells apart from the central nervous system constituting together with glial cells the enteric nervous system (ENS). The morphology of the ENS is characterized by intramurally located ganglionated and non-ganglionated plexus of different structure. The diversity of neurotransmitters synthesized by the different nerve cell types as well as the complex neuronal circuits establish the basis for the mediation of a coordinated intestinal motility. Subsequently abnormalities of the ENS may cause severe constipation. The most acknowledged intestinal innervation disorder represents aganglionosis (Hirschsprung's disease) characterized by the absence of intramural nerve cells and the hypertrophy of nerve fiber bundles within the affected intestinal segment. Non-aganglionic intestinal innervation disorders include intestinal neuronal dysplasia (IND), hypoganglionosis and heterotopic ganglia. The pathogenesis of intestinal neuronal malformations is mainly attributed to development disorders of the ENS, in part caused by genetic defects. Furthermore, the ENS can sustain damage during the postnatal period by ischemic, inflammatory, autoimmunological processes or neurotoxic agents. The histopathological diagnosis of intestinal innervation disorders is achieved by enzyme- and immunohistochemical methods. The examination of the ENS can be carried out on mucosal, deep submucosal or full-thickness biopsies using serial transverse sections as well as on intestinal whole-mount preparations allowing a three-dimensional demonstration and assessment of the intramural plexus. Structural abnormalities of the myenteric and submucosal plexus and an abnormal content of neurotransmitters have been considered to be responsible for primary chronic constipation. However, until now no unified pathophysiological concept has been established due to the partly contradictory findings. Therefore, an important goal in patients with chronic constipation should be a detailed quantitative and qualitative assessment of the underlying neurohistopathology. The correlation of these data with functional parameters of intestinal motility may represent an useful tool for the differential diagnostic and therapeutic considerations.

Chronic Disease↗
PubMed1998

Dermal microvasculature and tissue selective thinning techniques (ultrasound and water-jet) of short-time expanded skin in dogs.

Certain reconstructive procedures, like auricular reconstructions, require thin and well-vascularized skin. The aims of this study were to analyze if the increased survival of expanded skin flaps was due to morphologic changes of the dermis, if thinning of short-time expanded skin was possible without harm to the microcirculation and if tissue selective cutting methods could be used to resect subcutaneous fat without damaging its vessels. Eighty-two 200-ml expanders were implanted into the trunk regions of 26 beagles and filled immediately with sterile saline. In the first series of experiments, the expansion was terminated after intervals of 0.5-5 weeks and dermal vessels were analyzed morphometrically. In the second series the expanded flaps were raised after 2 weeks and thinned solely surgically or with the additional use of an ultrasonic knife or with cutting by water jet. In contrast to sham flaps, the expanded skin showed only very few areas of necrosis and these were located superficially in most cases. The relative volume of the dermal vessels and their quantity showed a significant increase after the expansion. Additionally, the subcutaneous tissue could be thinned down to 0.4 mm with the water-jet-cutter. Findings demonstrated that the method used could create a well-vascularized skin flap of minimal thickness that could be very helpful for special reconstructive procedures.

Adipose Tissue↗
PubMed1998

High contrast and homogeneous staining of paraffin sections of whole human brains for three dimensional ultrahigh resolution image analysis.

The gallocyanin chromalum stain belongs to the classical DNA-RNA staining techniques in histochemistry. It has some important features for successful object orientated image analysis of whole sections of the human brain. To obtain reproducible staining results with these large sections, the method of Einarson was adapted to image analytical requirements. We discuss staining in a warm staining solution, pH adjustment, and optimal stain composition. The embedding procedure for whole human brains is considered as well.

Brain↗
PubMed1997

[Imaging of laser thermokeratoplasty lesions by optical low coherence tomography and polarization microscopy after Sirius Red staining].

BACKGROUND: Information on the extent and degree of the thermal effect produced is of great importance for control of the laser dosage in laser thermokeratoplasty (LTK) and for postoperative follow-up. We investigated on acute LTK effects which information images obtained by optical low coherence tomography (OCT) offer compared to those obtained by polarization microscopy. METHODS: Porcine eyes were irradiated through a 400 microns quartz fiber using light from a laser diode emitting up to 300 mW at a wavelength of 1.86 microns. Thermal lesions of varying strength were scanned using an experimental OCT device with about 25 microns lateral and 20 microns axial resolution. Histologic evaluation of the scanned areas was done by polarization microscopy after Sirlus-Red staining, and similar lesions were also analyzed by TEM. RESULTS: Both methods differentiated three damage zones a transition zone, a zone of moderate coagulation, and a central zone of strong coagulation. In the transition zone, increased birefringence was seen in polarization microscopy, which correlated with increased light scattering seen in the OCT images. In the moderately coagulated zone, a decrease in birefringence was associated with an even stronger increase of the OCT signal. In the central zone, a loss of the fibrillar tissue structure was observed, which led to a complete loss of birefringence and a strong reduction of the OCT signal. CONCLUSIONS: Although OCT does not provide the detailed information on thermal changes of tissue seen by the histologic method, it offers information on the extent and degree of tissue changes without preparation artifacts and provides a non-invasive method of immediate and follow-up control of LTK lesions. A quantitative analysis of changes in corneal thickness and curvature is much simpler than by a slit lamp. Time-resolved measurements of corneal light scattering may be used for on-line control of the laser-light dosage during LTK.

Animals↗
PubMed1997

Histologic analysis of thermal effects of laser thermokeratoplasty and corneal ablation using Sirius-red polarization microscopy.

PURPOSE: To evaluate how well several histologic techniques differentiate degrees of thermally induced changes in corneal tissue after laser thermokeratoplasty (LTK) or corneal ablation. SETTING: Medical Laser Center Lübeck, Germany. METHODS: Corneas of freshly enucleated porcine eyes were treated with a continuous wave laser diode (1.86 microns) and a pulsed chromium-thulium-holmium: YAG laser (2.1 microns) to produce LTK lesions or ablated with a Q-switched and a free-running chromium-erbium: YSGG laser (2.70 microns), a free-running erbium: YAG laser (2.94 microns), and an argon-fluoride excimer laser (193 nm). The lesions were evaluated by light microscopy (LM) (hematoxylin and eosin, Azan, van Gieson's, and Masson-Goldner's trichrome stains), transmission electron microscopy (TEM), and polarization microscopy after Sirius-red staining. Sirius-red, a strongly elongated, birefringent molecule binding parallel to collagen molecules, was used to enhance corneal birefringence. RESULTS: With routine LM, it was difficult to discriminate the degrees of thermal alterations in LTK lesions. Combined Sirius-red staining and polarization microscopy distinguished between a strongly coagulated central zone and the transition zone to normal tissue. Sirius-red uptake was increased in both zones, reflecting the availability of new binding sites. The central zone appeared darker under polarization than normal collagen because of a loss of birefringence. Intrinsic birefringence was greatly reduced; however, form birefringence partly remained as long as some collagen fibrils were intact. In the center of very strong lesions, where the collagen was hyalinized, birefringence was completely lost because of the complete disintegration of the fibrillar structure, which was visible under TEM. The transition zone toward normal cornea showed increased birefringence because the natural birefringence was largely preserved and enhanced by the increased Sirius-red uptake. Mechanical stretching between neighboring LTK lesions was manifested by increased birefringence. CONCLUSION: Sirius red offered an improved and simple histologic method for analyzing thermal collagen changes. It may contribute to a better understanding of the working mechanisms of LTK and improve analysis of thermal effects in corneal ablation.

Animals↗
PubMed1997

Systematic investigations of the contrast results of histochemical stainings of neurons and glial cells in the human brain by means of image analysis.

The investigation of neurohistological specimens by image analysis has become an important tool in morphological neuroscience. The problems which arise during the processing of these images are non-trivial, especially if a pattern recognition of cells in the imaged tissue is intended. One of the major problems faced concerns the segmentation of structures of interest, whether cells or other histologic structures. The segmentation problem is often the result of an inappropriate staining procedure. For serious image analysis to be performed, the material under investigation must be optimally prepared. Spatially complex patterns, e.g. fuzzy-like neighbouring neurons, are easy to recognize for humans. But the integrative and associative performance of current artificial neuronal network schemes is too low to achieve the same recognition quality as humans do. Therefore, a general analysis of staining characteristics was performed, especially with respect to those stains which are relevant to object segmentation. Although most image analytical investigations of tissues are based on stained samples, a study of this type has not been previously conducted. Of the stains and procedures evaluated, the gallocyanin chrome alum combination staining provided the best stain contrast. Furthermore, this staining method shows sufficient constancy within different parts of the human brain. Even the fine nuclear textures are differentiable and can be used for further pattern recognition procedures.

Adult↗