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Biomedical subjects

R Eggers

Publications and source records attributed to R Eggers.

At least 19 recordsLinked to original sources
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↗
PubMed1996

The ossification centre of the talus.

The ossification of the talus was studied in plastinated and histological preparations of normal feet of eight newborn children. Quantitative data on the newborn talus were obtained with the IBAS image analysis system and by point counting methods. In the newborn talus up to 24 percent of the talar anlage already consists of bony tissue. The ossification centre is situated in the neck, which includes the non-articulating surfaces of the talus. Periosteal bone joins the endochondral centre below and, in well-differentiated specimens also above. The basal periosteal collar forms the surfaces of the sinus and canalis tarsi, whereas the cranial bony collar is included in the tibiotalar joint. The histological architecture of these periosteal collars differs. Four arteries contribute to the blood supply of the talar ossification centre.

Bone Development↗
PubMed1996

[Intraluminal expansion of a small intestine segment--animal experiment principles and possible clinical application].

In this study we expanded ileal segments of 8 pigs with an intraluminal expander over a period of 6 to 8 weeks till the volume had reached approximately sixfold of the starting volume. The morphological and morphometrical examinations showed flattened villi with elongated crypts and especially an increase in the thickness of the muscularis. The villi appeared flattened through scanning microscopy as well, but the structure of the microvilli was nearly normal. The proliferative activity in the muscularis, estimated immunohistochemically by a monoclonal antibody against PCNA, showed a threefold increase. So it can be assumed, that the increased thickness of the muscle layer was caused not only by muscle cell hypertrophy but also by hyperplasia. The activity of the alpha-glucosidase, a brush border enzyme, was clearly reduced. The minor cause of this effect was the direct damage of the microvilli from the expander, but the major cause was the exclusion of the ileal segment from the small bowel passage and the resulting lack of nutrients. With our technique it seems possible to create an ileum pouch, a stomach substitute or a urinary bladder substitute.

Animals↗
PubMed1995

Quantitative investigations into the histostructural nature of the human putamen. II. The differentiated topological distribution of certain neuron type arrangements.

Several mathematical procedures have been worked out for describing quantitative arrangements of neurons, and especially subpopulations of neurons, in the human putamen. Visual point field analysis is a newly developed method for the qualitative recognition of the fuzzy clustering of types of neurons. Nearest neighbourhood analysis is an established procedure in stochastic geometry and image analysis. These cluster-analytical methods make possible the determination of local neuron topology. They represent an extension and application of the point pattern analysis (Diggle 1983), and are used here to calculate the statistical significance of certain arrangements of cells. The application of all these methods together revealed an interesting neuronal arrangement: type 1 neurons tend to remain at a certain distance from other type 1 neurons, whereas type 6 neurons lie close together.

Animals↗
PubMed1995

Quantitative investigations into the histostructural nature of the human putamen. I. Staining, cell classification and morphometry.

Combined staining with aldehyde and cresyl violet allows a reliable morphological distinction to be made between seven different types of neurons in the human putamen. We examined the age distribution of nearly 42,000 neurons in 27 normal putamina, using a semiautomatic morphometric procedure on defined tissue blocks. For morphometric evaluation and stereological calculations a section thickness of 20 microns is recommended. We modified routine aldehyde fuchsin cresyl violet combination staining for nervous tissue, since Braak's original method (Braak 1978, 1980) was developed for thick sections. The results show that neuronal density varies with age for the different types of neurons.

Adult↗
PubMed1994

Histopathological features of neuronal intestinal dysplasia of the plexus submucosus in whole mounts revealed by immunohistochemistry for PGP 9.5.

Neuronal intestinal dysplasia (NID) is wellknown, but its definition is a topic of debate. The histopathological diagnosis of NID is based on traditional enzyme-histochemical methods such as the acetylcholinesterase and dehydrogenase reaction on native cryosections. In this study, we have investigated the enteric nervous system in whole mount preparations of resected intestinal segments affected by NID of the plexus submucosus (type B). The plexuses of the tunica mucosa and tunica submucosa were visualized by immunohistochemical methods using a polyclonal antibody to protein gene produce 9.5 (PGP 9.5). PGP 9.5 is a novel general cytoplasmatic marker specific for the nervous system. The morphology of the plexuses is revealed in full, making possible changes easily discernible. Known pathological findings of the NID can be identified and judged more precisely with this method. Numerous enlarged nerve trunks run within the tunica submucosa and tunica mucosa. Hyperplastic ganglia with an unusually high nerve cell number in the tunica submucosa can be demonstrated as well as heterotopic nerve cells in the tunica mucosa.

Adolescent↗
PubMed1994

Eradication of poliomyelitis in South Africa.

An international campaign under the leadership of the World Health Organisation is underway to eradicate polio from the world by the year 2000. South Africa may already be free of polio. However, to ensure eradication we need to move from a polio control programme to a polio eradication programme. This necessitates the institution of a surveillance programme for acute flaccid paralysis (AFP) and improvement of the delivery of polio vaccine. All children with AFP (including those with suspected Guillain-Barré syndrome) should be investigated with stool culture to exclude polio. Primary care services need strengthening so that oral polio vaccine coverage greater than 90% is achieved in all regions by all authorities. Outbreak response activities need to be developed. Consideration needs to be given to national immunisation days and mopping-up activities.

Child↗
PubMed1993

Evaluation of the 13CO2 kinetics in humans after oral application of sodium bicarbonate as a model for breath testing.

The kinetics of 13CO2 have been investigated following oral administration at five doses between 12.5 and 100 mg of 13C labelled sodium bicarbonate to 10 healthy subjects in a randomized study. Sodium bicarbonate in this study served as a model compound for carbon dioxide/bicarbonate generated in breath tests. Exhalation of 13CO2 into breath was monitored by stable isotope ratio mass spectrometry. The kinetics of 13CO2 were characterized by an apparent terminal elimination half-life of 1 h and a mean recovery of 0.630 of the dose administered. The kinetics were not dose-dependent. These results were in agreement with the findings reported previously after i.v. application of sodium bicarbonate.

Administration, Oral↗
PubMed1990

Triple staining of brain tissue for neuronal classification.

The described triple staining (PAP, aldehydefuchsin, and cresyl violet) enables the distinction of different neuronal types with regard to their content of neurotransmitters or neuropeptides and their lipofuscin pigmentation respectively. The use of filters improves the contrast of immunohistochemical and lipofuscin staining, and facilitates the differentiation of neurons under the microscope. An additional important point is the advantage that perikaria can be measured in the usual morphometric manner.

Brain↗
PubMed1989

Is there a correlation between morphological and cytogenetic findings in placental tissue from early missed abortions?

A retrospective study of 200 missed abortions was performed to determine whether morphological criteria alone are sufficient to ascertain a chromosomal aetiology. Placental changes were classified into five morphological and four morphometric groups, according to the severity of alterations, and were then correlated with the cytogenetic data. The rate of chromosome anomalies was approximately 50% and was thus not significantly different within the groups II-V, but it was 80% in group I, which covered the most severe placental alterations, namely the partial hydatidiform moles. There was a high incidence of triploidies in group I, trisomies with obligatory early lethality in groups II and III, and X-monosomies in group III. Our findings do not support previous evidence regarding the specificity of certain villous alterations in association with chromosome aberrations. Indeed, they indicate that the placental villi may react similarly to chromosomal and non-chromosomal disturbances and that placental morphology depends on the severity and the temporal onset of the underlying disorder rather than on its type. With respect to chorionic villus samplings (CVS), this would mean that an abnormal villous structure may be suggestive for a chromosome anomaly but does not exclude a normal karyotype.

Abortion, Missed↗
PubMed1988

Increased systemic availability of albendazole when taken with a fatty meal.

We have studied the systemic availability of oral albendazole in 6 patients with echinococcosis either fasting or with breakfast. Albendazole sulphoxide, the pharmacologically active principle, was assayed by HPLC. Mean plasma concentrations and AUCs were 4.5 times higher when albendazole was given with breakfast than when administered in the fasting state. We conclude that therapy of echinococcosis with albendazole requires the drug to be taken with meals and that administration on an empty stomach might be more appropriate when intraluminal effects are desired, e.g. for intestinal parasites.

Adult↗
PubMed1988

Steady-state extrarenal sorbitol clearance as a measure of hepatic plasma flow.

Hepatic plasma flow was assessed with sorbitol (hepatic extraction = 0.96) at steady state. After infusion of 50 mg/min for 3 h, total and renal sorbitol clearances were calculated, and the extrarenal clearance was obtained by taking the difference between the two. In normal volunteers, the mean (+/- SD) extrarenal sorbitol clearance was 10.6 +/- 2.1 ml/min.kg. In patients with various liver diseases, it was correlated more closely to the fractional clearance of indocyanine green (r = 0.83, n = 57) than the galactose elimination capacity (r = 0.66, n = 55). Hepatic vein catheterization showed that the hepatic extraction of sorbitol was always much higher than the extraction of indocyanine green; there was no evidence for extrahepatic, extrarenal sorbitol elimination. On the basis of these findings, sorbitol is kinetically superior to indocyanine green and, although the noninvasively determined extrarenal sorbitol clearance at steady state may not be equal to total hepatic plasma flow, it may at least be regarded as a measure of parenchymal liver plasma flow.

Adult↗