Receptive field structure of area 19 as compared to area 17 of the cat

A total of 139 cells from area 19 along with a comparison sample of 172 cells from area 17 were classified using a system proposed by Orban and Kennedy, following Henry and consisting of 4 basic cell ‘families’, namely S,C,A and B, each having an end-stopped member: HS, HC, HA and HB. The two basic parameters separating the 4 families are firstly spatial overlap of ON and OFF subregions and secondly receptive field (RF) width. Spatial overlap was studied quantitatively in a number of these cells using multiple presentations of stationary slits or moving light and dark edges. RF width was determined quantitatively using bars moving at different velocities across the RF.It was found that cells with spatially nonoverlapping and overlapping subregions are present in both areas. S and HS cells, which shows similarities with simple cells, were encountered in area 19 but they constituted only 18% of the population as opposed to 55% in area 17. C and HC cells, reminiscent of complex cells, were about as common in area 19 as in area 17. In both areas C cells were the only group which consistently discharged equally well or better in response to diffuse light turned on and off than when presented with light bars. A and B families formed a minority in both areas. Area 19 contained a larger proportion of nonoriented and undriveable units, as well as a special category of cells preferring stimuli with a width larger than the length (‘rectangle cells’).RF width was generally larger in area 19 than in area 17 and its distribution in area 19 showed distinct peaks. In the part of area 19 subserving central vision these peaks appeared with a periodicity of 0.8°, suggesting that cells in this zone are supplied by one or more rows of a uniform set of afferents having a RF cetner diameter of about 0.8°. The identification of this population as W-relay cells is supported by the long latencies found in cells from this part of area 19.It is concluded that the basic principles underlying the structure of the RF are similar in both areas 19 and 17.     

Replantation of the hallux by microsurgical techniques

Summary In this report three cases of successful hallux replantation are presented. The indications for this type or surgery are discussed on the basis of the functional results of these replantations. In our opinion, corrective surgery is indicated in all cases of traumatic hallux and/or multiple-toe amputations.

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Zusammenfassung Es wird über drei erfolgreiche Großzehenreplantationen berichtet. Anhand der funktionellen Ergebnisse wird die Operationsindikation zu diesen Replantationen diskutiert. Nach unserer Auffassung besteht bei Großzehen- and Mehrzehenamputationen eine absolute Operationsindikation.

     

Microsatellite GT polymorphism in intron 2 of human Toll-like receptor (TLR) 2 gene and susceptibility to periodontitis

As pattern recognition receptor, Toll-like receptor (TLR) 2 is a signal molecule essential for the cellular response to Porphyromonas gingivalis. A recently described guanine-thymine (GT) repeat microsatellite polymorphism of the human TLR2 gene leads to impaired promotor activity. A total of 380 patients with chronic periodontitis and 590 unrelated healthy control individuals of Caucasian descent were genotyped for the GT repeat microsatellite polymorphism of the TLR2 gene. The mutations were identified with polymerase chain reaction followed by sizing of GT repeat length. The number of GT repeats ranged from 13 to 29 in both study groups. There was no significant difference between periodontitis patients and healthy controls regarding the frequency of GT repeats (p = 0.365). Subclassification of alleles into three subclasses (S allele, M allele, and L allele) revealed no significant association (p = 0.810). Moreover, also the comparison of the summarized prevalence of S and L alleles (high promotor activity) with that of the M allele (low promotor activity) was not significantly different among study groups (p = 0.377). The susceptibility to chronic peridontitis was not associated with the functional effective GT repeat microsatellite polymorphism in the human TLR2 gene.     

Purinergic P2X7 receptors regulate secretion of interleukin-1 receptor antagonist and beta cell function and survival

Aims/hypothesis  In obesity, beta cells activate compensatory mechanisms to adapt to the higher insulin demand. Interleukin-1 receptor antagonist (IL-1Ra) prevents obesity-induced hyperglycaemia and is a potent target for the treatment of diabetes, but the mechanisms of its secretion and regulation in obesity are unknown. In the present study, we hypothesise the regulation of IL-1Ra secretion by purinergic P2X₇ receptors in islets. Methods  Production and regulation of P2X₇ were studied in pancreatic sections from lean and obese diabetic patients, non-diabetic controls and in isolated islets. IL-1Ra, IL-1β and insulin secretion, glucose tolerance and beta cell mass were studied in P2x7 (also known as P2Rx7)-knockout mice. Results  P2X₇ levels were elevated in beta cells of obese patients, but downregulated in patients with type 2 diabetes mellitus. Elevated glucose and non-esterified fatty acids rapidly activated P2X₇ and IL-1Ra secretion in human islets, and this was inhibited by P2X₇ blockade. In line with our results in vitro, P2x7-knockout mice had a lower capacity to secrete IL-1Ra. They exhibited severe and rapid hyperglycaemia, glucose intolerance and impaired beta cell function in response to a high-fat/high-sucrose diet, were unable to compensate by increasing their beta cell mass in response to the diet and showed increased beta cell apoptosis. Conclusions/interpretation  Our study shows a tight correlation of P2X₇ activation, IL-1Ra secretion and regulation of beta cell mass and function. The increase in P2X₇ production is one mechanism that may explain how beta cells compensate by adapting to the higher insulin demand. Disturbances within that system may result in the progression of diabetes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

A645G (Lys216Glu) polymorphism of the bactericidal/permeability-increasing protein gene in periodontal disease

Bactericidal/permeability-increasing protein (BPI) is a member of the pattern recognition receptors of the innate immune system and recognizes lipopolysaccharides (LPS), a bacterial component belonging to the pathogen-associated molecular patterns (PAMPs). BPI mediates the neutralization of LPS and increases the phagocytosis and cytotoxicity against bacteria. Recently, the functionally effective polymorphism A645G resulting in the amino acid alteration Lys216Glu has been described. The aim of the study was to investigate the association of the A645G polymorphism with chronic periodontal disease. The study population comprised 123 patients with periodontal disease (36 with mild, 52 with moderate and 35 with severe periodontitis) and 122 healthy, unrelated control individuals. Genotyping of the BPI gene polymorphism A645G (Lys216Glu) was performed by polymerase chain reaction and restriction fragment length polymorphism analysis. Statistical analysis was carried out employing the chi(2) test with Yates correction. Genotype and allele frequencies of the polymorphism tested herein showed no significant differences between periodontal disease as compared to the control group. The frequencies of the G allele were 52.4% in patients with periodontal disease and 49.2% in the control individuals (P = 0.528). Moreover, no significant associations could be detected after stratification for disease severity and according to gender. The present study does not give evidence for the contribution of the BPI gene to the genetic background of chronic periodontal disease.     

Cytotoxic and genotoxic effects of resin monomers in human salivary gland tissue and lymphocytes as assessed by the single cell microgel electrophoresis (Comet) assay

Malignant tumors of the three major pairs and the numerous minor salivary glands in humans are rare, and little is known about their various etiologies. Considering the fact that resin monomers from dental restorative materials are released into the saliva and diffuse into the tooth pulp or gingiva, mucosa, and salivary glands, this may potentially contribute to tumorigenesis. Resin monomers may also be reabsorbed and reach the circulating blood as well. Whereas the cytotoxic potential of some components has been clearly documented, data on genotoxicity in human target cells require further investigation. In the present study, genotoxic and cytotoxic effects of three common methacrylates are investigated in human samples of salivary glands and peripheral lymphocytes. The Comet assay was used to quantify DNA single strand breaks, alkali labile and incomplete excision repair sites in salivary gland probes and lymphocytes of 10 volunteers. The xenobiotics investigated were triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and 2-hydroxyethylmethacrylate (HEMA), with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) as controls. DNA migration was analyzed using the tail moment according to Olive (OTM). Cytotoxicity was monitored using trypan blue staining. With TEGDMA concentrations at 10(-5)m (10(-3)m), UDMA at 10(-7)m (10(-7)m), and HEMA at 10(-3)m (10(-5)m) significant enhancements of DNA migration were achieved in tissue cells (lymphocytes) as compared to the negative controls. At higher concentrations of up to 2.5x10(-2)m, induced DNA migration was expressed by OTM at 10.7 for TEGDMA in tissue cells (8.7 in lymphocytes), 10.5 for UDMA (6.4), and 9.7 for HEMA (6.1). The viability of the cell systems was not affected as concerns the threshold level for the assay of 75% viable cells except for the highest concentration tested for TEGDMA and UDMA in tissue cells. At higher concentration levels, all tested substances induced significant enhancement of DNA migration in the Comet assay as a possible sign for genotoxic effects in human salivary glands and lymphocytes. These data add to the results of prior studies in human peripheral lymphocytes and give evidence of a possible risk factor for tumor initiation in human salivary glands.     

Ambiguity in Eric Kandel's neuroscientific basis of psychiatry

The philosophical principles underlying the work of Eric Kandel are investigated on the basis of his innovative paper entitled 'A new intellectual framework for psychiatry' (Kandel 1998). A careful analysis of the concepts involved reveals some ambiguity in Kandel's proposition in the mind-body debate. On the one hand Kandel uses formulations that are compatible with (classical) psychophysical identity theories; on the other hand he expresses views that actually have more in common with non-eliminative physicalism (or epiphenomenalism). In addition, he weakens his position by using misleading metaphors an analogies. This can lead to what is known as the 'mereological fallacy'. The final part of the article examines what this ambiguity tells us about Kandel's views on psychotherapy and the social justification for psychiatry. Kandel's approach can lead to a pointless narrowing down of the psychiatrist's normative role and to an over-restrictive attitude to psychotherapy.