PubMed Health⌕ Search

Biomedical subjects

U Rinne

Publications and source records attributed to U Rinne.

8 recordsLinked to original sources
PubMed1990

Striatal kinetics of [11C]-(+)-nomifensine and 6-[18F]fluoro-L-dopa in Parkinson's disease measured with positron emission tomography.

The kinetics in brain of the dopamine reuptake blocking agent [11C]-(+)-nomifensine and the L-dopa analogue 6-[18F]fluoro-L-dopa were compared in 3 patients with idiopathic Parkinson's disease and age-matched healthy volunteers using positron emission tomography. Regional uptake was analyzed and quantified according to a 3-compartment model. Retention of both tracers in striatal regions of the parkinsonian patients were reduced compared with the healthy volunteers mainly in the putamen, while the caudate nucleus was only mildly affected. The reductions were considerably less than the decrease previously reported postmortem for striatal dopamine content in the basal ganglia of patients with Parkinson's disease. A fairly constant ratio between 6-[18F]fluoro-L-dopa utilization and [11C]-(+)-nomifensine binding in the caudate nucleus and the putamen were found in both groups unrelated to the size of the estimated parameters. This indicates that a limiting factor for the utilization of exogenous levodopa in Parkinson's disease may be a reduced transport capacity for the amino acid into the dopaminergic terminals.

Adult↗
PubMed1990

CQA 206-291: a novel dopamine agonist in the treatment of Parkinson's disease.

The antiparkinsonian efficacy and tolerability of CQA 206-291, a novel ergoline derivative with potent dopamine agonist properties, were studied during 2 months of treatment in 72 parkinsonian patients. In 36 de novo patients (patients who have not previously been treated with levodopa or dopamine agonists), CQA 206-291 was studied in an open design, while in 36 levodopa-treated patients, CQA 206-291 was studied in a randomized, double-blind, parallel-group, placebo-controlled design. CQA 206-291 induced in both groups a significant antiparkinsonian effect with an effective dose range of 5-30 mg/day. The spectrum of adverse events was similar to what is commonly observed with dopamine agonists. Further studies are required to assess the putative therapeutic advantages of CQA 206-291 when compared to other antiparkinsonian drugs.

Aged↗
PubMed1981

Termination of cortical afferents on identified neurons in the caudate nucleus of the cat. A combined Golgi-EM degeneration study.

A combined Golgi/electron microscopic technique was used to investigate tne fine structure and synaptology of Golgi-stained spiny neurons in the caudate nucleus of the cat. In order to study the termination sites of cortical afferents on Golgi-stained spiny neurons, cortical fibres were caused to degenerate by making extensive cortical lesions 3 days prior to fixation of the animals. When examined in the electron microscope, perikarya of labelled spiny neurons have a round nucleus, a few mitochondria and microtubules, and a poorly developed Golgi apparatus and rough endoplasmic reticulum. Only rarely are axo-somatic contacts seen. Labelled dendrites exhibit a moderate number of microtubules and sometimes elongated mitochondria. Numerous labelled spines are seen in the vicinity of their parent dendrites. They are contacted by smaller type I and type III boutons and larger type IV boutons (Hassler et al. 1978). Large boutons filled with clear round vesicles establish symmetric contacts with labelled dendritic shafts. Degenerating boutons of cortical afferents are seen in contact with spines and, more rarely, with dendritic shafts of Golgi-stained spiny neurons. All degenerating boutons synapsing with labelled structures are found some distance from the cell body. No contacts of degenerating cortical boutons with the soma or with stem dendrites of Golgi-stained spiny neurons are found.

Afferent Pathways↗
PubMed1981

Large dense-core vesicle exocytosis and membrane recycling in the mossy fibre synapses of the rabbit hippocampus during epileptiform seizures.

The ultrastructure of the hippocampal mossy fibre layer was studied in ultrathin sections and freeze-fracture preparations of rabbits under deep Nembutal anaesthesia, after recovery from ether anaesthesia, and 40 min after a single injection of methoxypyridoxine, that is, during the second generalized seizure discharge. The giant mossy fibre boutons contain two types of vesicles: evenly distributed, small round clear vesicles (50 nm) and a few scattered large dense-core vesicles (100 nm). In rare instances fusion of dense-core vesicles with the presynaptic membrane was observed. No differences in the morphology of the mossy fibre synapses were found between anaesthetized and unanaesthetized animals. During epileptiform seizures, however, the size and shape of clear and dense-core vesicles varied greatly. The active synaptic zones were covered with large, core-containing omega profiles or bumps and indentations. Only dense-core vesicles seem to undergo exocytosis. A fusion of clear vesicles with presynaptic membrane was not observed. Various explanations for the fact that only dense-core vesicles seem to undergo exocytosis are discussed. The hypothesis is put forward that in the mossy fibre bouton two morphologically and functionally distinct populations of synaptic vesicles exist and that only one of them undergoes visible irreversible exocytosis, whereas the majority, that is, the small vesicles discharge their transmitter by reversible fusion. After MP injection features of membrane retrieval were also prominent. Frequently, at the borders of the active synaptic zones coated membrane convolutes of both pre- and postsynaptic membranes had invaded the terminals as well as the postsynaptic spine. Thus, in contrast to electrical stimulation, the self-sustained seizures allows energy-expensive processes such as extensive membrane internalization to take place during the interictal pauses.

Animals↗
PubMed1978

Selective degeneration of two out of the nine types of synapses in cat caudate nucleus after cortical lesions.

In the cat caudate nucleus the same nine types of synapses are found as in putamen and fundus striati. The three parts of the striatum in the strict sense do not differ in the morphological differentiation of synapse types but only in their quantitative distribution. One-third of all synapses in the caudate nucleus are axo-spinous type IV synapses with a curved and divided asymmetric contact. This strongly suggests that the caudate nucleus interneuronal apparatus is dominated by centre-median input, in contrast to the putamen which is controlled by the cortico-striatal input to its internuncial cells and by its strong intrastriatal feedback mechanism. Extensive destruction of the convexity of the cortex and the medial cortex in one hemisphere results in dark degeneration of a large proportion of two of the nine types of caudate synapses: a) the axo-dendritic type VII synapses exciting the large spiny caudate neurons and b) the axo-spinous type III synapses making contact with the small spiny neurons of the interneuronal cell apparatus.

Animals↗
PubMed1977

Calcium-induced displacement of membrane-associated particles upon aggregation of chromaffin granules.

Isolated chromaffin granules incubated in 10 millimolar calcium chloride aggregated, forming contact sites with a pentalaminar membrane structure. These circular attachment sites were free of membrane-associated particles, which accumulated at the periphery. Incubation in 20 millimolar ethylenediaminetetraacetic acid reversed these changes, which are regarded as initial events in the membrane fusion reaction.

Adrenal Medulla↗