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J Wester

Publications and source records attributed to J Wester.

9 recordsLinked to original sources
PubMed1989

Local cerebral glucose uptake in anatomically defined structures of freely moving rats.

Two limitations of the classical [14C]2-deoxyglucose (DG) method are the severe stress to which the restrained animals are exposed, and the difficulties with the anatomical analysis of the autoradiograms. The present study describes modifications which circumvent these limitations. Firstly, rats are provided with two chronic indwelling cannulas to allow blood sampling under unrestrained conditions. Absence of stress is demonstrated by low plasma corticosterone levels in the cannulated rats at the start of the experiment. The second modification concerns the image analysis system. The image of the autoradiogram is superimposed on the image of the identical histologically stained section in order to improve the accuracy of the structure identification. This approach enables the operator to delineate the anatomical brain structure in the histologically stained section and quantify the glucose uptake in the autoradiogram generated from this section. The reproducibility of the present quantitative measuring system is illustrated by glucose uptake measurements in different laminar zones of the various fields in the dorsal hippocampal formation. It is concluded that the present technical improvements of the classically applied [14C]2-deoxyglucose technique provide favourable conditions for the quantitative study on cerebral glucose uptake in normally behaving animals.

Animals↗
PubMed1979

Morphology of the hemostatic plug in human skin wounds: transformation of the plug.

The transformation of hemostatic plugs in human skin wounds was studied in vivo after bleeding had stopped. Standardized bleeding time incisions were made on the dorsal side of the forearm of four normal male volunteers. The wounds were excised by punch biopsy 10 minutes, 30 minutes, or 2 hours after they had been made and studied by light and electron microscopy. The wounds were filled with red blood cells, and a network of fibrin strands was found in the wound, particularly near transected vessels. Polymorphonuclear leukocytes were encountered within transected vessels and at 2 hours also in the wounds and in concentric rings around the vessels up to 0.5 mm. from the wound. On top of the wounds a superficial scab, consisting of red blood cells and presumably air-dried proteins, had formed. Hemostatic plugs were found at the ends of transected blood vessels. At 10 minutes the plugs consisted of largely degranulated platelets which showed strong interdigitation. Fibrin was still absent from the center of the plugs. At 30 minutes the platelets became less densely packed, and small fibrin fibers were deposited between the platelets in large peripheral areas of the plugs. At 2 hours some of the platelets had assumed rounded shapes with few interdigitations and larger spaces between them. Areas in the plug with platelets that had lost their integrity alternated with areas where platelets still had their cytoplasmic matrix and were interdigitated. Fibrin fibers were especially demonstrable between the degenerated platelet vesicles. This occurred everywhere in small hemostatic plugs and in the periphery of larger plugs. In one individual it was also observed in the center of large hemostatic plugs. In the other individuals fibrin was present centrally as amorphous dark staining material which was fibrillar in tangential sections.

Adult↗
PubMed1978

Evaluation of platelet tests for measurement of cell integrity.

Various tests were evaluated for their capacity to differentiate between platelet suspensions with different degrees of cell damage. Those suspensions were prepared by simultaneous isolation of platelets from the same platelet-rich plasma (PRP) using the following procedures: 1. centrifugation at 4 degrees C with EDTA 2. gel filtration in Tangen's buffer 3. gel filtration in Ca2+-free Tyrode's soltuion 4. gel filtration in Ca2+-free Tyrode followed by dehydration against polyethylene glycol 20,000 and 5. albumin density gradient centrifugation. In these suspensions and in the original PRP the following parameters were studied: 1. morphology; 2. aggregability upon ADP addition; 3. platelet factor 3 availability; 4. uptake of 14C-serotonin and 3H-adenine; 5. metabolism of 3H-adenine and adenylate energy charge; 6. endogenous total ATP, ADP and serotonin and 7. lactate dehydrogenase (LDH) activity. Quantitation of pseudopod formation in the light or electron microscope and log dose response studies for ADP-induced aggregation proved to be the most sensitive and reproducible of the tests studied. Additional information could be obtained from measurement of the 3H-label in the ATP and hypoxanthine-inosine fractions and calculation of the adenylate energy charge. Determination of platelet factor 3 availability or uptake studies of 14C-serotonin and 3H-adenine were less suitable for discriminating between cell suspensions. Data for total ATP and serotonin concentrations and LDH activity differed between the cell suspensions but instead of detecting various degrees of cell damage they reflected alterations in platelet population caused by the isolation procedures.

Adenine↗
PubMed1978

Morphology of the early hemostasis in human skin wounds: influence of acetylsalicylic acid.

The in vivo formation of hemostatic plugs was studied in humans in skin wounds made using the template bleeding procedure of Mielke (34). The wounds were excised by punch biopsy 10 seconds, 30 seconds, 2 minutes, and 3 minutes after they were made. The wounds were V-shaped and approximately 0.4 mm. deep. Within 30 seconds small hemostatic plugs were observed at the end of transected vessels. The plugs grew in size in the subsequent minutes and became impermeable. The platelets degranulated and formed pseudopods which became strongly interdigitated. The platelets at the periphery of the plugs showed discontinuities of the membranes. Cytoplasmic matrix and cell organelles had disappeared in many of these peripheral cells. Small fibrin fibers were already found at 30 seconds, mostly along the margins of the wounds and also at the periphery of the hemostatic plugs. Fibrin was absent from the center of the plugs and from the lumen of transected vessels. When part of a plug was extending into the vessel lumen, the platelets inside the vessel were less degranulated and less interdigitated than the rest of the plug. The effect of acetysalicylic acid (ASA) was studied in wounds before and 2.5 hours after ingestion of 2 gm. of ASA. Wounds were excised by punch biopsy 3 or 10 minutes after they had been made. Platelets in ASA were less degranulated, had fewer pseudopods, and showed less interdigitation than platelets in control plugs. Ballooning and fibrin deposition were similar in control and ASA plugs. Pronounced differences between control and ASA plugs were observed in a subject who exhibited a considerably prolonged bleeding time after ASA. The ASA plugs were very large; many plugs had fused and in addition numerous small platelet clumps, most likely fragments from the plugs, were found in the superficial scab of the wound. It is postulated that ASA plugs are less stable due to decreased interdigitation. This allows more disruption of the plugs and rebleeding. Consequently, more platelets are needed and longer time is required for hemostasis to occur.

Adult↗
PubMed1977

ADP-induced refractory state of platelets in vitro. II. Functional and ultra studies on gel filtered platelets.

Gelfiltered platelets (GFP) in calcium free Tyrode solution containing albumin, glucose and adenosine deaminase were preincubated with 1 micronM 14C-ADP or 0.15 M NaCl (control) at 37 degrees C. The breakdown of extracellular 14C-ADP was markedly inhibited in this medium. No aggregation took place without fibrinogen, but the platelets underwent a disc to sphere transformation with development of refactoriness towards ADP. Presence of 2 mM CaCl2 in the incubation medium did not prevent refractoriness as reported earlier with washed rabbit platelets. When the ADP degrading enzyme, apyrase, was added at 30 min of incubation a partial recovery of the aggregability was observed. Electron microscopic studies showed that the partial restoration of the aggregation response, due to ADP degradation by apyrase, was accompanied by a return of discoidal morphology of the platelets. The ultrastructural studies showed further that spherical form with large number of pseudopods is not by itself a necessary or sufficient indication of platelets in a refractory state. However, the results indicated that spherical platelets are more vulnerable to external factors. It was concluded that refractoriness was mainly caused by a direct effect on the platelets by ADP itself, but the studies also suggested that deteriorating, irreversible, intracellular changes may take place when platelets are in spherical shape. An artificial medium, mechanical stress, incubation at 37 degrees C are factors that probably speed up these changes.

Adenine↗
PubMed1977

The hemostatic plug.

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Adenosine Diphosphate↗
PubMed1976

Preparation of concentrated platelet suspensions by dehydration against polyethyleneglycol 20,000.

Gel filtered platelet suspensions were concentrated by repeated dehydration against polyethyleneglycol 20,000 followed by dialysis against slightly hypotonic buffer. This method increased the platelet concentration 2-3 times with a recovery of 80-100%. The final cell suspension closely resembled the original platelet rich plasma as tested by a number of platelet tests.

Adenosine Diphosphate↗
PubMedDate not supplied

Cholinergic innervation and topographical organization of muscarinic binding sites in rat brain: a comparative autoradiographic study.

Employing [3H]hemicholinium-3 ([3H]HC), [3H]pirenzepine([3H]PZ) and [3H]quinuclidinyl benzilate ([3H]QNB), autoradiographic binding studies were performed to identify and quantitate the localization of high-affinity choline carriers, M1-subtype of muscarinic binding sites and a mixed population of M1- and M2-subtypes of muscarinic binding sites, respectively, in 38 anatomically defined areas of rat brain. Labelling of adjacent brain sections with [3H]HC, [3H]PZ and [3H]QNB revealed different topographical binding patterns. [3H]HC binding, which is supposed to reflect cholinergic innervation, was dense in the nucleus accumbens, olfactory tubercle, caudate putamen, basolateral amygdaloid nucleus and the interpeduncular nucleus. Moderate but heterogeneous binding was found in thalamic, hypothalamic, hippocampal and cortical areas. Maximal [3H]PZ binding was observed in the nucleus accumbens, olfactory tubercle and in discrete substructures of the hippocampus, e.g. CA1 and dentate gyrus. Binding to other hippocampal and cortical areas was intermediate, whilst minor binding was found in thalamic, hypothalamic and brain stem areas. The binding of [3H]QNB was more evenly distributed over the brain as compared to that of [3H]PZ. [3H]QNB clearly exceeded the binding of [3H]PZ in the thalamus, hypothalamus and brain stem. A relationship was found between the topography patterns of the [3H]PZ and [3H]QNB binding sites. However, some brain areas showed preference for one of the two ligands, pointing to a distinct localization of M1- and M2-subtypes of muscarinic binding sites. Although M1 sites appeared to predominate in the basal ganglia, hippocampus and cortex, some heterogeneity was observed indicative of the minor occurrence of M2 sites within these structures. There was no relationship between the density of the presumed cholinergic innervation and the binding capacity of either of the muscarinic sites in the various brain areas. However, a relationship was found between M2-selectivity and [3H]HC binding, pointing to a possible presynaptic localization of the M2-sites. In addition, it is suggested that distinct cholinergic cell groups might project their fibres to brain areas containing particular subsets of postsynaptic muscarinic binding sites.

Animals↗