Selective effects of aniracetam across receptor types and forms of synaptic facilitation in hippocampus.

Aniracetam reversibly increased synaptic responses mediated by the AMPA but not the NMDA subclass of glutamate receptors in hippocampus and was considerably more potent than structurally similar nootropics. The drug had greater effects on field excitatory postsynaptic potentials (EPSPs) in the dentate gyrus and CA1 region than it did in the CA3 region, suggesting that it differentiates between variants of the AMPA receptor. Ligand binding to glutamate receptors in synaptosomal membrane fractions was minimally changed by aniracetam. Finally, the percent facilitation produced by aniracetam in the CA1 region was not reduced by any of three treatments (4-aminopyridine, changes in extracellular calcium concentrations, paired-pulse stimulation) that affect release but, in accord with a previous report, was substantially decreased by long-term potentiation. These results support the conclusion that aniracetam selectively increases the conductance of a subgroup of synaptic AMPA receptors in hippocampus and suggest that receptor changes underlie the expression of long-term potentiation.     

Biomechanical aspects of mandibular growth

The subject of this study was to analyse how functional parameters of stomatognathic systems are influenced by growth. For this purpose, two cephalometric radiographs of 65 patients with class-II-relation treated with functional appliances were superimposed on the occlusal plane. The two patient groups consisted of 32 open bite and 33 deep bite cases. The direction of the condylar growth significantly differed for both cases. Nevertheless the hypothesis could be confirmed that the original functional structure was hardly affected by growth.     

Colour doppler flow imaging of the carotid arteries

Summary 53 patients with carotid artery atherosclerosis were examined by colour Doppler flow imaging. These results were compared with real time duplex sonography and continuous wave Doppler sonography. In 48 low degree stenoses (<50%) the B-mode showed 36 smooth and 12 ulcerated plaque surfaces. In 24 high degree stenoses (>50%) 10 plaques were smooth and 14 ulcerated. In the low degree stenoses, which exhibited smooth surfaces in B-mode examination, colour flow Doppler showed nine additional cases with turbulences in the area of the stenotic site. This indicates that plaque ulcerations in low degree stenoses are underestimated. In contrast, in nearly all cases with high degree stenoses marked turbulences could be demonstrated by colour Doppler flow imaging independent of the B-mode showing regular or ulcerated plaque surfaces. Additionally, the duplex ultrasound diagnosed a carotid artery occlusion in 11 cases, but the colour coded Doppler was able to assess a remaining blood flow in two out of these 11 cases. Our results suggest that the colour Doppler flow imaging as a noninvasive technique is an advantage in diagnosing plaque ulcerations and it is more precise in diagnosing carotid occlusions than duplex-sonography is.     

Do different ethnic groups need different sun protection?

Background: In the present study, the transmission of sunlight trough the human skin barrier into the living tissue was investigated in the spectral region between 280 and 700 nm.
Methods: The experiments were performed with a fiber-based spectrometer on sliced skin obtained from volunteers with different skin types. One fiber was positioned directly on the skin surface and the second one underneath the skin samples. The distribution of the sunlight under the epidermis was determined.
Results: Significant differences were found in the absorption properties of the different skin types, which were mainly determined by the variations in melanin concentration and distribution. It was found that sunscreens for specific ethnic groups need different combinations of UV filters, if a balanced relation between ultraviolet B (UVB) and ultraviolet A (UVA) protection is to be obtained. On the other hand, it could be demonstrated that the human skin is also well protected against visible and near-infrared light by melanin.
Conclusions: The higher the skin type category, the better the protection in the visible part of the spectrum of the sun. This stimulates the hot discussion at the present time, as to whether sunscreens should also contain protection compounds in the visible and near-infrared parts of the spectrum.     

Serial evaluation of left ventricular function by radionuclide ventriculography at rest and during exercise after orthotopic heart transplantation

Discrepant results have previously been reported concerning long-term left ventricular function in the human transplanted heart as assessed by radionuclide ventriculography. In this study, radionuclide ventriculograms were obtained at rest and during exercise in 19 patients <6 months, 7–12 months, 13–24 months and >24 months after transplantation. Ejection fraction decreased significantly from <6 months to 13–24 months after transplantation (rest: 69.1%±9.7% to 56.7%±8.3%, P<0.05; exercise: 70.4%±11.3% to 59%±8%, P<0.05). Heart rate increased significantly during exercise after >2 years (90.2±10.5 beats/min to 103.5±15 beats/min, P<0.05) but not within 6 months after transplantation (98.5±12.8 beats/min to 99.07±15.8 beats/min). Left ventricular end-diastolic volume remained unchanged. Peak filling rate at rest decreased significantly from 4.2±0.96 edv/s <6 months after transplantation to 3.3±0.66 edv/s (P<0.05) 13–24 months and 3.3±0.64 edv/s (P<0.05)>24 months after cardiac transplantation. Exercise peak filing rate did not change significantly. It is concluded that radionuclide ventriculography demonstrates a decrease in systolic left ventricular function in the long-term course after cardiac transplantation. A significant increase in exercise peak heart rate may be due to autonomic reinnervation. Differences in the literature concerning left ventricular function may be due to different observation intervals following cardiac transplantation.     

In-vitro growth patterns of bone marrow erythroid progenitors from patients with post-renal transplant erythrocytosis

Background: Erythrocytosis is relatively common after renal transplantation and is associated with a higher risk of thromboembolism. Its aetiology is unclear and there is still debate about the most frequently suggested causes. The culture in vitro of erythroid progenitors is regarded as a useful tool for the differential diagnosis of patients with unclear erythrocytosis. We studied the growth in vitro of bone marrow erythroid progenitor from renal transplant patients with erythrocytosis and controls without erythrocytosis. Subjects and methods: Thirteen renal transplant patients with erythrocytosis and 12 normocythaemic renal transplant controls were studied. The clinical characteristics of these patients were evaluated and serum erythropoietin (Epo) and ferritin levels were determined. Bone marrow erythroid progenitors were cultured both with and without the addition of Epo to the medium. Results: Samples from six polycythaemic patients and seven controls did not grow spontaneously in the absence of exogenous Epo. Three cases of post-transplant erythrocytosis and five controls produced CFU-E, but not BFU-3. A few CFU-E and BFU-E grew spontaneously in samples from four polycythaemic patients but not in samples from the controls. Addition of 1 unit per millilitre Epo caused similar increases in the number of colonies in both polycythaemic patients and controls. Of the nine patients eligible for follow-up, all four with spontaneous growth of BFU-E had transient erythrocytosis and four of the five patients with no spontaneous growth or spontaneous growth of CFU-E only had persistent erythrocytosis requiring treatment with ACE inhibitors. Conclusions: Pathophysiology of post-transplant erythrocytes is heterogenous. In one-third of the patients, there was unexpected, spontaneous and transient growth of BFU-E which was not predictive of permanent erythrocytosis. The results of stem-cell studies suggest that in these cases erythrocytosis may be caused by defective regulation of erythroid progenitor proliferation, possibly due to particular cellular interactions or the effect of cyclosporin on erythropoiesis.