Experimental Proof for Electrochemical Non-Equilibrium Saturation Currents in Organic Crystals

For the same redox ion, diffusion controlled currents have been compared which were obtained at organic crystals and at a gold electrode. These experiments yield quantitative proof for electrochemical saturation currents in organic crystals with electrolytic contacts. Essential for this result is a modified voltage step method which enables an application of a high voltage simultaneous with the first contact between the crystal surface and the charge injecting electrolyte. The conditions necessary for the occurrence of a saturation current are discussed which also determine the electrochemical nature of this current corresponding to an ideal non-equilibrium between redox system and organic crystal.

Notizen: Zur Beteiligung des Triplettzustandes im Kristall an der sensibilisierten Erzeugung von Defektelektronen in aromatischen Kohlenwasserstoffen

The steady-state spatial distribution has been calculated for triplet excitons generated at the surface of an anthracene crystal. The dependence on the light intensity has been discussed for a hole generation and delayed fluorescence, due to the triplet excitons.

Bronchopneumonia disguising lung metastases of a painless central chondrosarcoma of pubis

Chondrosarcoma is a generally locally malignant chondroid-forming bone tumor with a low potential for distant metastases. A small and completely painless central chondrosarcoma of pubis metastasizing to the lungs in a 63-year-old woman with bronchopneumonia is reported. Here we emphasize the mimicry and low growth of the chondrosarcoma and the easiness with which the diagnosis in completely asymptomatic patients can be missed. Although painless chondrosarcoma metastasizing to lung is rather rare, this tumor should be always included in the differential diagnosis of malignancies in this age category.

[Multiple space-occupying lesions of the liver: a rare differential diagnosis]

The case of a 73-year-old female patient with a known increase in tumor markers is described. The course of this patient shows that a definitive diagnosis can sometimes not be achieved with comprehensive laboratory and imaging investigations alone.

[Interdisciplinary guidelines on diagnosis and treatment for extracerebral amyloidoses--published by the German Society of Amyloid Diseases (www.amyloid.de)]

Within the past 10 years, a new range of knowledge has been achieved in the field of amyloidosis, especially with regard to pathogenesis, diagnosis and therapy. Amyloidosis leads to variable and distinct symptoms and is caused by different underlying conditions. Some amyloidoses are acquired secondary to a chronic condition; others are caused by genetic mutations. Amyloid and amyloidosis occur more frequently than they are perceived. Among the frequent localized forms are the cerebral amyloidosis linked to Alzheimer disease (AD) and the pancreatic amyloidosis linked to diabetes mellitus. Among the most frequent systemic (extracerebral) forms is AL amyloidosis, which often has a poor prognosis and if untreated can rapidly lead to death. Systemic amyloidosis that happen at infancy are mainly AA amyloidosis that can progress to death already at early or at middle adulthood. Amyloidosis can be treated but therapeutic success significantly depends upon early diagnosis and proper classification of the amyloid type. It is mandatory that differential diagnosis demonstrate the presence of amyloid and clearly identify the type of the disease. Development of methods and techniques have contributed to improvements in the diagnosis and treatment. Early diagnosis and proper classification of amyloid is decisive for therapeutic options and upon them depend quality of life and mortality. The therapeutic spectrum is various and includes organ transplantation, chemotherapy, and anti-inflammatory strategies. Gene therapy and biological active substances have to be considered in the near future.

Femtosecond transfer dynamics of photogenerated electrons at a surface resonance of reconstructed InP(100)

Time-dependent two-photon photoemission spectra are used to resolve the femtosecond dynamics of hot electrons at the energetically lowest surface resonance of reconstructed InP(100). Two different cases are studied, where electrons either are lifted into the surface resonance via a direct optical transition or are captured from bulk states. These data are the first of this kind recorded with a time resolution below 70 fs. The microscopic analysis shows that electron-phonon scattering is a major mechanism for electron transfer between surface and bulk states.

[Hereditary amyloidoses associated with transthyretin mutations]

Hereditary amyloidoses form a clinically and genetically heterogeneous group of autosomal-dominantly inherited diseases characterized by the ubiquitous extracellular deposit of fibrillary aggregated proteins. Main components of these unsolvable deposits are physiologic proteins that became amyloidogenic through genetically determined conformation changes resulting in an increase in beta-sheet structures. In the vast majority of cases, the offending protein is variant transthyretin (TTR), of which over 80 mutations are known. Among these, substitution of valine by methionine in position 30 (TTR-Met30) is the most commonly encountered. In typical cases, TTR amyloidoses present with polyneuropathy, carpal tunnel syndrome, autonomic insufficiency, cardiomyopathy, and gastrointestinal features, occasionally accompanied by vitreous opacities and renal insufficiency. Rarely, involvement of the leptomeningeal or meningovascular structures dominates the clinical picture. The clinical expression is highly variable, with many atypical manifestations. Asymptomatic mutations have recently been identified. The age of onset varies greatly between early adulthood and old age. Late-onset atypical manifestations and occurrence of asymptomatic carriers render identification of affected family members difficult despite autosomal-dominant inheritance. Orthotopic liver transplantation (OLT) is the only effective therapy available today. This OLT stops progression of the disease, which is otherwise invariably fatal, by removal of the main production site of the amyloidogenic protein. However, cardiac involvement may progress after OLT for unknown reasons. The indication for OLT and its success depend on the grade of cardiovascular and autonomic dysfunction at the time of surgery, age, comorbidity, and type of mutation. Alternative treatment modalities with drugs stabilizing the native tetrameric conformation of TTR, inhibiting fibril formation or breaking beta-sheet structures, are currently being intensively studied.

Transthyretin-associated neuropathic amyloidosis. Pathogenesis and treatment

Hereditary amyloidoses form a clinically and genetically heterogeneous group of autosomal dominantly inherited diseases characterized by the deposit of insoluble protein fibrils in the extracellular matrix. They typically present with polyneuropathy, carpal tunnel syndrome, autonomic insufficiency, and cardiomyopathy and gastrointestinal features, occasionally accompanied by vitreous opacities and renal insufficiency. Other phenotypes are characterized by nephropathy, gastric ulcers, cranial nerve dysfunction, and corneal lattice dystrophy. Rarely, involvement of the leptomeningeal or cerebral structures dominates the clinical picture. The age at onset is as early as 17 and as late as 78 years. The basic constituents of amyloid fibers are physiologic proteins that have become amyloidogenic through genetically determined conformation changes. Mutated transthyretin (TTR), formerly termed prealbumin, is the most frequent offender in hereditary amyloidosis. Orthotopic liver transplantation (OLT) stops the progression of the disease, which is otherwise invariably fatal, by removing the main production site of amyloidogenic protein. The indications for OLT and its success depend on the grade of cardiovascular and autonomic dysfunction at the time of surgery, age, comorbidity, and type of mutation. Alternative treatment modalities with drugs stabilizing the native tetrameric conformation of TTR and inhibiting fibril formation are currently being studied.

Ameliorating effects of RU 47213, a novel oral and long-lasting cholinomimetic agent, on working memory impairments in rats

The anti-amnesic effects of RU 47213 [1-(4-chlorophenoxycarbonyl)-1,2,5, 6-tetrahydropyridine-3-carboxaldehyde-O-methyloxime], a prodrug with oral and long-lasting cholinergic activity, were evaluated on working memory impairments, using tasks of unequal levels of difficulty involving the same reinforcement and motivation in rats: a spatial-based task in a radial maze and a delayed reinforced alternation task in a T-maze. Tetrahydroaminoacridine (THA; tacrine), a cholinesterase inhibitor was used as a reference. Groups of rats were trained in an automated radial maze or T-maze until they had attained an asymptotic level of performance. On test days, memory impairment was produced by administration of scopolamine (0.1 mg/kg s.c.) 15 min prior to testing. Both THA (1.3, and 5 mg/kg) and RU 47213 (0.2, 0.5, 1, and 2 mg/kg) given prior to testing markedly reduced or suppressed the scopolamine induced working memory deficits in both tasks. This activity was evidenced by either a significant decrease in the number of errors or an increase in the number of correct responses. These results show that RU 47213 possesses the capacity to reduce memory deficits induced by an impairment of cholinergic transmission in the rat.

Effects of RU 52583, an alpha 2-antagonist, on memory in rats with excitotoxic damage to the septal area

The anti-amnesic action of RU 52583, an alpha 2-adrenergic receptor antagonist, was evaluated through performance of spatial tasks in a radial maze by rats with N-methyl-D-aspartic acid (NMDA) lesion of the medial septal (MS) nuclei. Memory performance of lesioned or sham-operated rats was evaluated by measuring reference memory as long-term maintenance of an acquired performance and working memory or memory for recent events. The lesion: a produced significant impairments of the animals' memory performance, b) significantly reduced the sodium-dependent high-affinity choline uptake in the hippocampal formation, and c) deeply disrupted cholinergic hippocampal theta waves. Oral administration of RU 52583 at 1 and 2 mg/kg (tested doses: 1-5 mg/kg) prior to performance of the task markedly reduced memory impairments, whereas idazoxan, another alpha 2-adrenergic receptor antagonist, had no effect at tested doses (2-5 mg/kg). Cholinergic drugs--arecoline at 0.1 and 1 mg/kg (tested doses: 0.05-1 mg/kg) and physostigmine at 0.02 and 0.1 mg/kg (tested doses: 1, 2, and 5 mg/kg)-administered intraperitoneally showed a tendency to alleviate memory deficits. The present results show that the alpha 2-adrenergic antagonist RU 52583 possesses cognition-enhancing properties in rats with damage to the septohippocampal system.

[Epithelioid leiomyosarcoma of the stomach with hemorrhagic ascites]

In two men (69 and 65 years old) a gastric epithelioid leiomyosarcoma more than 25 cm in diameter first manifested itself by an increase in abdominal girth and ascites. In case 1, a cylindrical mass was palpable in the abdomen increasing in size over two years. Sonography and computed tomography showed a large cystic tumour which could not be related to any one organ. Cytology of the ascites fluid did not reveal any tumour cells. At operation a pedunculated tumour, 29 x 20 x 9 cm, was found, originating from the stomach. Six litres of ascites fluid were aspirated. There were no detectable abdominal metastases. The patient died nearly 4 years later after the tumour had been resected, three further laparotomies had to be performed because of extensive metastases to peritoneum and liver from the leiomyosarcoma. In case 2, no abdominal mass was palpable, but the patient's girth had increased over the last year. Sonography revealed a cystic tumour, about 30 cm in diameter. Examination of haemorrhagic ascites fluid (700 ml) did not show any tumour cells. The tumour, originating from the stomach wall, was excised (no metastases were seen). The patient remains symptom-free after 35 months.

The Roman strains of rats as a psychogenetic tool for pharmacological investigation of working memory: example with RU 41656

This study examined the effects of RU 41656, a dopaminergic D2 agonist, on the differential working memory performances and on the differential activities of the neurochemical systems of the Roman high (RHA) and Roman low (RLA) avoidance strains of rats. Compared with RLA, RHA performed worse in three tests of working memory (spontaneous alternation, radial maze and object recognition) and had higher levels of exploratory locomotor activity. Hippocampal and frontal cortex choline acetyltransferase (ChAT) activities were lower in RHA. Frontal cortex DA and DOPAC levels, hippocampal and striatal 5-HT and NA levels were higher in RHA. RU 41656 induced a significant improvement in working memory performance of RHA, whereas in RLA it had no effect. It decreased exploratory locomotor activity in both strains. ChAT activity in hippocampus was not affected by RU 41656 in either strain, whereas in frontal cortex it was increased in RHA but not in RLA. Hippocampal NA levels were decreased by RU 41656 in RHA but not in RLA. These results confirm previous data concerning the promnesic effect of RU 41656 and extend the finding that the Roman strains are a psychogenetic model for the behavioural, neurochemical and psychopharmacological study of the working memory in rats.

Selective fimbria and thalamic lesions differentially impair forms of working memory in rats

Several series of experiments were designed to compare the effects of selective lesions of the fimbria or of thalamic nuclei on three different tasks involving working memory in rats: object recognition, place recognition, and the radial arm maze test. The main effects of fimbria lesions were as follows: they produced deficits in the radial maze; object recognition was spared or even facilitated, whereas place recognition was impaired. Electrolytic lesions of either centromedian-parafascicularis (CM-Pf) or dorsomedialis (DM) nuclei produced highly significant deficits in the radial maze test but spared object and place recognition. Ibotenate lesions of the CM-Pf had no effect on any test, which means that the critical structure in the effects of the electrolytic lesions of the CM-Pf was the fasciculus retroflexus (FR). These data may contribute two main points to animal models of hippocampal and thalamic amnesia: (1) different forms of working memory in rats might have different neural bases and (2) the FR may be involved in learning and memory processes.

Contribution of the Roman strains of rats to the elaboration of animal models of memory

Performances of male rats of the Roman High (RHA)- and Roman Low (RLA)-Avoidance strains were compared along four essential dimensions: working memory, reference memory, spontaneous locomotion and avoidance conditioning. Performances of RLA and RHA rats were significantly different for each dimension. As constantly reported, RHA rats were by far superior to RLA in avoidance conditioning. They had also higher levels of locomotor activity. On the opposite, RLA performed better than RHA in an appetitive working memory task, the delayed reinforced alternation, and were also superior in an appetitive reference memory task, the 5-unit linear maze. These results confirm the fact that RLA rats may acquire positively reinforced learning more rapidly than RHA rats and that the differences in active avoidance behavior between the two strains depend more on differential freezing behavior than on learning or memory capacities. Beyond the problem of the characterization of the Roman strains, these data might give indications on the relationships between behavioral tests widely used in rats, and on their use as memory models.

Roman strains as a psychogenetic model for the study of working memory: behavioral and biochemical data

Performances of male rats of the Roman High- (RHA), Roman Control- (RCA) and Roman Low- (RLA) Avoidance strains were compared in two working memory tests, a spatial one, the radial maze, and a nonspatial one, an object recognition test. The same rats were subjected to measures of emotional reactivity and of different forms of motor activity and finally to measures of cholinergic and aminergic activities in the hippocampus, frontal cortex and striatum. Compared to RHA, RLA performed better in the two working memory tests, displayed "anxiety" and had also lower levels of exploratory locomotor activity. Hippocampal ChAT activity was higher in RLA than in RHA. Levels of DA and DOPAC in the striatum were higher in RLA compared to RHA, whereas in the frontal cortex they were lower. For most of these measures, RCA were intermediate between RLA and RHA. These results confirm and extend the finding that the Roman strains are not only a genetic model for two-way avoidance conditioning but also for working memory.

Effects of transient cerebral ischemia on the hippocampal dentate theta (theta) profile in the acute rat: a study 4-5 months following recirculation

This study mainly describes the long-term effects of 20 min of cerebral ischemia on the profile of the presumed cholinergic theta rhythm in the rat dorsal hippocampal formation during ether anesthesia and injection of the muscarinic agonist agent arecoline. The experimental data were collected 4-5 months after ischemia. They show that ischemia results in a statistically significant reduction in both superficial and deep theta recorded from the CA1 area of the hippocampus and the dentate gyrus, respectively. Amplitude reduction is similar for both rhythms and co-varies positively with the extent of CA1 stratum pyramidale damage which, from light microscope observation, appeared to be the major neuroanatomical consequence of ischemic insult in the dorsal hippocampal formation. The medial septal nucleus-diagonal band of Broca complex involved in theta generation did not suffer visible anatomical damage. Moreover, no significant alteration in the spatial distribution and the density of hippocampal dentate acetylcholinesterase reaction product was seen in ischemic animals. These histological data were statistically confirmed by computerized image analysis. Finally, this is the first investigation to show that transient interruption of cerebral blood flow results in a long-lasting alteration of theta rhythm which is probably the major aspect of the basic activity of the hippocampal formation. Thus, the present findings obtained in the acute rat at 4-5 months postischemia confirm and extend, in most respects, our previous results collected in the chronic animal 2-29 days following 4-vessel occlusion. Possible significance of these findings for the hypothesis of the dependent generation sites of superficial and deep thetas in the hippocampus assumed to be crucial in learning and memory, is discussed.