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Biomedical subjects

J van Marle

Publications and source records attributed to J van Marle.

At least 55 records · Page 3Linked to original sources
PubMed1994

Localization and quantification of the insulin-like growth factor-1 receptor in mouse articular cartilage by confocal laser scanning microscopy.

Insulin-like growth factor-1 (IGF-1) is an essential anabolic growth factor in the regulation of cartilage metabolism and exerts its effects by binding to the IGF-1 Type 1 receptor on the chondrocyte membrane. We have localized and quantified in situ IGF-1 receptor expression in intact articular cartilage of normal mice. The IGF-1 receptor was detected immunohistochemically with antibodies to the IGF-1 receptor and visualized with conventional light microscopy and confocal laser scanning microscopy (CLSM). CLSM analysis enabled us to distinguish IGF-1 receptor immunoreactivity on the chondrocyte cell membrane from intracellular staining. We have established two approaches to quantify in confocal images low levels of fluorescence intensity of the immunolocalized IGF-1 receptor at the chondrocyte membrane, i.e., mean pixel measurement and area measurement. The majority of IGF-1 receptor fluorescence intensity was localized on chondrocytes in the middle and deeper zones of cartilage, whereas chondrocytes in the surface zone exhibited negligible fluorescence. The variable distribution of IGF-1 receptor in chondrocytes of articular cartilage suggests that effects of IGF-1 on chondrocytes may be distinctly heterogeneous in the different mouse articular cartilage zones.

Animals↗
PubMed1993

Permanent increase of the GAD67/synaptophysin ratio in rat cerebral cortex nerve endings as a result of hypoxic ischemic encephalopathy sustained in early postnatal life: a confocal laser scanning microscopic study.

The aim of this study was to investigate whether perinatal hypoxia-ischemia preferentially destroys GABAergic nerve endings in rat cerebral cortex tissue which, in its turn, could then account for the reported higher risk of developing epilepsy later in life. To that end rat pups, with an age of 12-13 days postnatally, were unilaterally exposed to hypoxic-ischemic conditions. After a survival period of 2 to 6 months, the animals were sacrificed by perfusion fixation and their brains were used for cutting transversal vibratome and frozen sections. These sections were double-stained with primary antibodies against one of the two GABA synthesizing enzymes, glutamic acid decarboxylase with a mol. wt. of 66,600 (GAD67) and one of the intrinsic membrane proteins of small synaptic vesicles, synaptophysin, followed by fluorophore-conjugated second antibodies. By using the confocal laser scanning microscope, we determined the ratio between the amount of GAD67/synaptophysin immunofluorescence in nerve endings per unit volume of tissue in the hypoxia-damaged neocortex. It turned out that this ratio, contrary to expectations, was significantly higher in the hypoxia-damaged cortical areas than in matched areas on the contralateral side. It appeared, moreover, that this effect was directly proportional to the severity of the incurred damage. The conclusion was drawn that these observations do not support the hypothesis that perinatal hypoxia-ischemia ultimately leads to a preferential loss of GABAergic nerve endings in the damaged neocortex and, as such, to a shortage of inhibition.

Animals↗
PubMed1992

Morphologic changes of extrahepatic bile ducts during obstruction and subsequent decompression by endoprosthesis.

The morphologic changes of the extrahepatic biliary tract during obstruction and the effects of biliary decompression by means of an endoprosthesis on the bile duct wall were studied by light microscopy and scanning electron microscopy. Common hepatic duct biopsy specimens and bile cultures were obtained during surgery from 30 patients with a distal common bile duct obstruction caused by a tumor. Thirteen patients had obstructed bile ducts of 3 weeks' duration (group A). Seventeen patients had had jaundice for a period of 4 weeks and had subsequently undergone preoperative endoscopic biliary stenting for a period of 4 weeks (group B). Three autopsy specimens from patients without hepatobiliary disease served as controls. The results showed that the initial dilatation and thickening of the obstructed ducts in group A were associated with a mild inflammation, a moderate degree of fibrosis, and local epithelial disintegration. The presence of an endoprosthesis, however (group B), induced severe inflammatory changes with considerable fibrosis and ulcerative lesions, resulting in markedly thickened ducts with lumina approximating the diameter of the stent. Three of 13 (24%) bile cultures in group A were positive and 14 of 17 (82%) in group B were positive.

Bile Duct Neoplasms↗
PubMed1989

Presynaptic effects of spider toxins: increase of high affinity uptake in the arthropod peripheral glutamatergic system.

In contrast to the reported effects of polyamines on the high affinity neurotransmitter uptake, two polyamine-like spider toxins significantly increase the high affinity uptake of glutamate as demonstrated with high resolution autoradiography. The effects of both spider toxins were compared to those of a polyamine toxin from the wasp Philanthus triangulum, which is known to inhibit the high affinity glutamate uptake.

Animals↗
PubMed1989

The venom of Ampulex compressa--effects on behaviour and synaptic transmission of cockroaches.

1. The solitary wasp Ampulex compressa stings a cockroach, Periplaneta americana, twice. 2. The first sting into the ventral thorax results in a transient paralysis. During this paralysis the wasp stings the suboesophageal ganglion, which gradually results in a permanent deactivation. 3. The venom gland is a paired and highly branched organ, with a common ductus venatus. The large lumen is lined with a folded cuticula. No venom reservoir is present. 4. Extract of the venom gland induces a slow contraction of the guinea pig ileum. 5. The agonist present in the venom cannot be identified with a known agonist. 6. Venom gland extract blocks synaptic transmission from the cercal nerve to giant neurons in the sixth abdominal ganglion of the cockroach. 7. The block develops gradually, like the gradual appearance of the effects of the sting into the suboesophageal ganglion on the behaviour of the cockroach.

Animals↗
PubMed1989

Effect of cholesterol nucleation-promoting activity on cholesterol solubilization in model bile.

Human bile contains a factor with cholesterol nucleation-promoting activity that binds to concanavalin A-Sepharose. In this study we have investigated the effect of this activity on the dynamics of lipid solubilization in supersaturated model bile. A concanavalin A binding protein fraction of human bile was mixed with model bile and the effect on the distribution of cholesterol and phospholipid between mixed micelles and phospholipid/cholesterol vesicles was studied by means of density gradient ultracentrifugation. The nucleation-promoting activity containing fraction induced a transfer of cholesterol and phospholipid from the micellar to the vesicular phase. This led to a decrease in the density of the vesicular fraction. We have also studied the effect of promoting activity on the nucleation time of an isolated vesicle fraction. A decrease of the nucleation time of 10.7 +/- 1.3 to 2.3 +/- 0.3 days was observed. In conclusion, a concanavalin A binding protein fraction from human bile stimulated cholesterol nucleation via a double effect; it increased the amount of vesicular cholesterol and phospholipid, and it also directly induced nucleation of cholesterol from the vesicles.

Bile↗
PubMed1988

A scanning electron microscopic study of the common bile duct epithelium in the rabbit during experimental biliary tract obstruction.

Complete biliary obstruction was induced in rabbits by distal ligation of the common bile duct (CBD). The epithelial surface of the CBD was studied with scanning electron microscopy (SEM) at 1-6 days post-ligation. Concomitant biochemical assessments and pressure measurements in the CBD were performed. SEM of non-ligated CBD showed that the epithelium is arranged in folds and clefts, the latter displaying interdigitating cellular processes. At 2 days post-ligation, the epithelial clefts were focally distended showing marked dehiscence of the cellular processes with exposure of the subepithelial connective tissue layer. At 4-6 days post-ligation, extensive defects in the epithelium were observed, frequently with a sharp demarcation between intact epithelium and exposed connective tissue stroma.

Alkaline Phosphatase↗
PubMed1987

Acute acalculous cholecystitis in critically ill patients. Case reports.

Five cases of acute acalculous cholecystitis complicating trauma or an existing major illness are reviewed. This condition differs from classical cholecystitis in many aspects. It is serious and often fatal (3 of our patients died) with multifactorial pathogenesis. Clinical signs and laboratory investigations may be difficult to interpret because of associated conditions. Serial ultrasound examinations in high-risk patients in whom the disease is suspected should lead to earlier diagnosis. Early cholecystectomy is mandatory.

Acute Disease↗
PubMed1986

Dexamethasone reduces the high-affinity binding of hemicholinium-3 to rat phrenic nerve endings in vitro: an autoradiographic study.

Receptor autoradiography has revealed high-affinity binding sites for hemicholinium-3 (HC-3) in the phrenic nerve endings of rat diaphragm. It has been demonstrated that 200 nM dexamethasone (Dex) in vitro reduces the binding of HC-3 to these high-affinity sites. It seems likely that the decrease in inhibitory effects of HC-3 on choline uptake and acetylcholine synthesis in rat diaphragm caused by Dex, should be the result of an interference of Dex with the binding of HC-3 to its high affinity sites.

Animals↗
PubMed1986

Reduction of high affinity glutamate uptake in rat hippocampus by two polyamine-like toxins isolated from the venom of the predatory wasp Philanthus triangulum F.

Two components of the venom of the predatory wasp Philanthus triangulum F. significantly reduce--to a greater or less extent--the high affinity uptake of glutamate in rat hippocampus. A concentration of 10 microM delta-PTX caused a reduction of 74%, while the other component, beta-PTX, at the same concentration, caused a reduction of 18%. Hence the effect of delta-PTX on high affinity glutamate uptake in the hippocampus is comparable with its effect on high affinity glutamate uptake in insect neuromuscular junctions. Contrary to our previous findings that beta-PTX has no effect on high affinity glutamate uptake in insect glutamatergic terminal axons, however, beta-PTX significantly reduces high affinity glutamate uptake in the hippocampus, albeit less effectively than delta-PTX.

Animals↗
PubMed1986

Presynaptic, high-affinity glutamate uptake in excitatory neuromuscular junctions of the retractor unguis muscle of the locust: determination of the Km value using high resolution autoradiography.

Using high resolution autoradiography the Km of the presynaptic, Na+-dependent and aspartate inhibited, high affinity glutamate uptake in insect neuromuscular junctions was determined. The values found (approx. 15 microM) did not differ for the glia and terminal axons. This Km value agrees with those values determined by classical biochemical techniques for presynaptic high affinity uptake systems in insect neuromuscular junctions and glutamatergic central nervous systems.

Animals↗
PubMed1986

Computerized pattern recognition used for grain counting in high resolution autoradiographs with low grain densities.

Using a video-image system coupled to a minicomputer with commercial image handling software, autoradiographic grains displayed in dark-field are counted with a fast (ca. 3.5 min for 120,000 microns 2) and reliable (false scores less than 5%) grain-recognizing FORTRAN program executed in the users memory. The grain counts are printed in a raster of adjustable size overlying a bright-field image, so that the counts can be related directly to the underlying histological structures.

Autoradiography↗
PubMed1985

Selectivity of the uptake of glutamate and GABA in two morphologically distinct insect neuromuscular synapses.

The common inhibitor (CI) and slow excitor tibiae (SETi) innervated slow muscles 135cd of the locust Schistocerca gregaria were incubated under high-affinity uptake conditions either in [3H]GABA or in [3H]glutamate. [3H]GABA is accumulated in the glia of the nerve endings of the CI as well as the SETi; however, it is accumulated only in the terminal axons of the CI, not in the terminal axons of the SETi. The grain densities above the glia and above the CI terminal axons are approximately 2 grains/micron2. After incubation in [3H]glutamate the grain densities above the CI terminal axons and the SETi terminal axons are approximately 4 grains/micron2; the grain densities above the glia of both types of nerve endings are approximately 17 grains/micron2. The relatively high labeling (3 grains/micron2) of the muscles after incubation in the presence of glutamate is ascribed to the high metabolic requirements of slow muscles. The conclusion is drawn that a high-affinity uptake system for GABA is present in the CI terminal axons and in the glia of both the CI and SETi nerve endings. However, while the glutamate uptake in the CI and SETi nerve endings of the slow 135cd is comparable to the high-affinity uptake of glutamate in the fast excitor tibiae (FETi) nerve endings of the fast retractor unguis muscle, a high-affinity uptake of glutamate was only demonstrated in the glia of both types of nerve endings. A high-affinity uptake in the terminal axons of the CI and SETi may be masked by an extensively low-affinity uptake of glutamate by the muscles.

Animals↗
PubMed1985

Dexamethasone affects radioactive choline uptake in rat diaphragm nerve endings and not in muscle fibres.

The initial rate of radioactive choline (Ch) uptake in the endplate-rich area (EPA) of both stimulated and unstimulated hemidiaphragms is significantly increased by 0.2 microM dexamethasone (Dex) in the presence of 10 microM Ch. In autoradiographs, the mean grain densities above the muscle fibres are not altered by Dex. The mean grain densities above the nerve endings are significantly increased in the presence of Dex in stimulated tissue, and slightly but not significantly increased in unstimulated tissue. There is a positive correlation between the initial rate of Ch uptake in the EPA and the amount of isotope in the nerve terminals, in the absence and presence of Dex. Without correcting for the large amount of diffusion which occurs, the ratio of the grain densities above the nerve terminals to that above the muscle fibres in the presence of Dex is 2.12 in stimulated tissue, and 1.40 in unstimulated tissue. The ratio in the stimulated tissue is significantly greater than the control ratio in the absence of Dex (1.66). Therefore, Dex affects radioactive Ch uptake in nerve endings and not in muscle fibres in the rat diaphragm. The stimulation-induced increase in the uptake of isotope into the nerve endings is abolished in a Na+-depleted medium, and in the absence of Ca2+. Dex has no effect on this abolition. We conclude that relatively low concentrations of Dex affect Ch transport in rat diaphragm nerve endings by a mechanism as yet to be defined.

Animals↗