PubMed Health⌕ Search

Biomedical subjects

W Meier-Ruge

Publications and source records attributed to W Meier-Ruge.

At least 37 records · Page 2Linked to original sources
PubMed1989

Fibronectin content of the annulus fibrosus in diabetic and non-diabetic sand rats.

Annulus fibrosus of intervertebral discs from diabetic and non-diabetic sand rats were examined by microspectrophotometry for fibronectin content. This was higher in the diabetic animals both in the dorsal and ventral parts and in the outer and inner lamellae of the annulus. It is suggested that diabetes-related changes in fibronectin are similar to changes in annular collagen observed in species other than sand rats.

Animals↗
PubMed1989

Age-related changes in fibronectin in annulus fibrosus of the sand rat (Psammomys obesus).

Fibronectin stains were carried out and evaluated by microspectrophotometric techniques in annuli fibrosi of vertebral discs of sand rats (Psammomys obesus) of both sexes and two age groups, 13-18 months and over 2 years of age. The distribution of fibronectin in the annulus shows a centripetal gradient from the outer to the inner laminae. Fibronectin was significantly more abundant in the annuli of old than of young animals of corresponding sex. Sex differences were not significant. The dorsal segment contained more fibronectin than the ventral, but the difference was statistically significant only in the aged females. The outer laminae of the annuli appeared consistently higher in fibronectin content than the inner laminae.

Aging↗
PubMed1989

Quantitative morphology of the zinc-iodide-osmium (ZIO) stained synaptic vesicles.

A computer assisted morphometric method has been elaborated to quantify synaptic vesicles evidenced by means of the Zinc-Iodide-Osmium (ZIO) staining procedure in nerve endings of a very discrete area of the cerebellar granular layer: the glomerulus. The following parameters were calculated directly on electron microscopic negatives of 4.67 microns 2 of surface terminal area: number of vesicles per unit area (Na), and per unit volume (Nv), volume density (Vv), average diameter (d) and average volume of the single vesicle (V). Ultrastructural changes taking place at nerve endings also cover synaptic vesicles, thus quantitative studies regarding vesicle population at synaptic regions can be correlated to functional changes occurring in the process of chemical transmission and reflect the plasticity of synaptic junctional zones. Although this histochemical staining method generally is referred to as unspecific, after comparing our data with the available literature reports, we propose that ZIO-positive vesicles could have a physiological significance. These ZIO-positive organelles could take part in the intraterminal homeostatic control of Ca++ ions.

Animals↗
PubMed1988

Aquagenic pruritus. Water-induced activation of acetylcholinesterase.

Four patients with aquagenic pruritus (AP), one patient with polycythemia rubra vera, one patient with cold urticaria, and three normal control volunteers were studied to better understand the pathophysiology of water-induced itching. Punch biopsy specimens were taken before and after water contact; the specimens were immediately frozen, sectioned, and stained histochemically for acetylcholinesterase (AChE) activity. This was localized in the nerve fibers surrounding eccrine sweat glands and was quantified by microspectrophotometry. In AP and polycythemia rubra vera after water exposure a significantly increased AChE activity suggesting acetylcholine release was observed, whereas in the patient with cold urticaria and the controls, a significant decrease was noted. Two related patients with AP had an inherited abnormality of serum cholinesterase, which, however, had no obvious correlation with their particular disease. The proof of AChE activation might support the clinical diagnosis and indicate a hypothetical involvement of eccrine sweat glands in the pathogenesis of AP.

Acetylcholinesterase↗
PubMed1988

Quantitative morphology of synaptic plasticity in the aging brain.

Quantitation of synaptic ultrastructural changes is of great importance in neurobiology, since merely qualitative alterations, if not extreme, are not readily detectable. In the present paper we discuss our previous and present findings on the number (numerical density: Nv), size (average length of the synaptic profiles: L) and surface contact area (surface density: Sv) of the synaptic junctions in aging rodent and human brains. We found that number and size of the synapses are in a close inverse relationship so as to maintain the total surface contact are among the nerve cells constant. These three parameters are closely related to each other, their quantitation may thus represent a reliable index of the morphological aspects of synaptic plasticity, i.e. the modification of ultrastructure occurring at synaptic membranes after transient changes in synaptic activity. During aging, the morphological plasticity of synapses appears to be seriously impaired: the number of synapses and the total surface contact area among the nerve cells are markedly reduced. However, old nerve cells seem to retain the ability to modify their synaptic endings and to partially compensate for the reduced surface density of the contact zones by expanding the average size of the persisting junctions. Our recent studies on synaptic plasticity in human brains from old and demented subjects showed that while the size of the synaptic contacts remains constant, the numerical and surface densities undergo a further decrease in demented brains relative to that in normal aging.

Adult↗
PubMed1986

Effects of hyperinsulinism and of diabetes on proteoglycans of the intervertebral disc in weanling sand rats.

Weanling sand rats (Psammomys obesus) develop hyperinsulinemia or diabetes or both, if fed a standard laboratory diet without a supplement of fiber rich salt bush. The annuli fibrosi of hyperinsulinemic or diabetic animals, which are still hyperinsulinemic, show a slight but statistically significant increase in chondroitin sulfate and a lesser, statistically nonsignificant increase in keratan sulfate. Possible causes of these changes are discussed and the likelihood of a role of hyperinsulinism in their production is pointed out.

Animal Feed↗
PubMed1979

Accelerated ageing or selective neuronal loss as an important cause of dementia?

Extensive biochemical analysis of whole temporal lobe from cases of dementia and controls suggests that Alzheimer's disease is a primary degenerative nerve-cell disorder and not the result of accelerated ageing. There is selective loss of neocortical cholinergic neurones. Transmitter systems apart from the cholinergic system appears to be affected, but to a lesser extent, and there are no significant changes in the caudate nucleus. The change in cholinergic neurones has been confirmed in biopsy samples.

Aged↗
PubMed1979

Micropreparation techniques in quantitative histochemistry - density gradient centrifugation, manual microdissection and laser microbeam preparation of tissue.

Each quantitative histochemical problem needs its specific method for tissue preparation. In this connection two of the most important preparation methods, density gradient centrifugation and microdissection of freeze-dried tissue slices, are described. Density gradient centrifugation is a very effective procedure for preparative separation of cell particles such as cell nuclei. The details of the preparation of glial and neuronal cell nuclei are described. The in vitro phosphorylation of histone in the chromatin in relation to age is given as a practical example of the quantitative histochemical application to a preparation of cell nuclei. Other techniques of tissue preparation are the manual tissue microdissection according to Lowry and the Laser microbeam preparation. Advantages and disadvantages of both methods are compared. It is shown, that the introduction of Laser microbeam dissection technique, as alternative to manual microdissection, add new dimensions to Lowry's ultramicrochemical methods. One has greater freedom in the choice of the sample size and the number of samples dissected from the same slice. Furthermore, the need for a well-trained person for the preparation is eliminated. The preparation is also considerably less time consuming and easier to perform than the manual free hand preparation. Two quantitative histochemical methods used for the investigation of microdissected tissue samples are described: the gas-chromatography-massfragmentography (GC/MS)-method for determination of transmitters and its metabolites as well as the enzymatic cycling technique of Lowry. The GC/MS-method is explained with an example of noradrenaline and dopamine determination. The enzymatic cycling technique is demonstrated in combination with the Oil-Well-Technique for determination of the NADP-cycle.

Cell Fractionation↗
PubMed1978

Quantitative studies in the cerebral cortex of aging humans.

The capillary network of the human cerebral cortex was morphometrically investigated in a young, aged and aged hypertonic group. In the aging cortex, augmented values of capillary diameter and volume are accompanied by smaller distances between capillaries and an extended length per unit cortex volume. An increased capillary diameter of the aged hypertonic group is probably due to a high blood pressure. The regulating influence of the surrounding astroglia and the extracellular fluid on capillaries seems to lack. In comparison to normotonic brains, higher distances between capillaries and a decreased capillary length were measured.

Adult↗
PubMed1978

Effect of carotid ligation on cerebral tissue oxygenation in aging rat.

In order to test the ability of aged animals to compensate a cerebrovascular insufficiency, common carotid ligation was performed on young (12 months) and aged (30 months) rats. By using gold microelectrodes, the pO2 distribution in the cerebral cortex was registered for 1 h following the occlusion of the carotid arteries. It could be shown that, while the young group was able to compensate the reduction in arterial blood supply, the cortical pO2 distribution in the group of aged rats shifted towards a hypoxic profile. These results provide further evidence of the limited adaptability to functional demands with increasing age.

Aging↗
PubMed1978

Incorporation, after single and repeated application of radioactive labelled DH-ergot alkaloids in different organs of the cat, with special reference to the brain.

1 h after intravenous administration, 3H-DH-ergot alkaloids showed maximal uptake in the range of 10(-5)M in various visceral organs, and of 10(-7)M in most parts of the CNS of the cat. The clearance function in both groups of tissues was logarithmical linear, the slope of the straight line for the parts of the CNS being considerably flatter. Repeated administration of these drugs demonstrated a higher retention in the CNS than in the other organs. The single-dose level in the CNS is reinforced and, in contrast to liver and lung, maintained for at least 24 h.

Animals↗
PubMed1978

[Stereological investigation in the cerebral cortex of aging subjects (author's transl)].

Involving cortical regions, capillaries of the human cerebrum of two 19 and 27 years old men, a 69 years old woman and a 72 years old man were stereologically investigated by optical-electronic image-analysis. The cortical capillary net work was demonstrated by the alkaline phosphatase activity. Each cortex region comprised a determination of the stereological parameters diameter, projected area, specific surface area, capillary distances in linear direction of TV-lines and total length per unit cortex volume. A comparison between different cortex regions revealed a good correlation between increased values of the diameter and the projected area, a decreased specific surface area and diminished capillary distances, which entail a shortened distance of oxygen diffusion through the cortical tissue. During aging a diminished capillary surface area, which results from increased values of diameter and projected area is compensated by shortened capillary distances. Presumably an augmented capillary length is due to a condensation of the capillary net per unit cortex tissue. The behaviour of the registered stereological parameters seems to be an accommodation of the capillary net in the human cerebrum to metabolic and circulatory changes during aging.

Adult↗