Dentist phobia

This study analyzes so-called hopeless gaggers, i.e., patients in whom dental treatment and wearing of a prosthesis produced a retching or vomiting reaction, in order to investigate the sources and properties of this pathologic reaction. In 35 patients, an anamnestic inquiry, a determination of the reflexogenic zone, a recording of the peripheral pattern of the pathologic reflex, and extinction training were performed. A group of six normal persons served as a comparison group. It was shown that patients, in comparison with normals, had an enlarged receptive field, were sensitive to a broader population of stimuli, and showed precursors and aftereffects of the retching-vomiting not found in normals. This pathologic reaction was the symptom of different psychopathologic processes, such as specific fear, repugnance-fear-based disturbances, diffuse anxiety, goal-directed behavior, depressive states and, at least in one case, visceral pathology. The various patients differed with respect to properties of the reaction as well as in the sensitivity to the extinction procedure. It is discussed that different integrative nervous processes play a role in the origin and development of the syndrome: activation of unconditional reflexes, activation of classic and instrumental conditional reflexes, activation of such reflexes by an increase of the reactivity level of specific and unspecific structures of the brain, generalization of stimuli, etc.     

Cytoplasmic juxtamembrane region of the insulin receptor: a critical role in ATP binding, endogenous substrate phosphorylation, and insulin-stimulated bioeffects in CHO cells.

We have expressed in CHO cells a mutant receptor (IR delta 960) from which 12 amino acids in the juxtamembrane region (A954-D965), including Tyr960, have been deleted. The mutant receptor bound insulin normally but exhibited an increased Km for ATP during autophosphorylation. Upon prolonged incubation in vitro, or at high ATP concentrations such as those observed in vivo, autophosphorylation of IR delta 960 was similar to wild type, and the in vitro phosphotransferase activity of the autophosphorylated IR delta 960 was normal. These results suggest that the deletion did not cause a nonspecific structural disruption of the catalytic domain of IR delta 960. In vivo autophosphorylation of the IR delta 960 receptor was reduced by 30% after 2 min of insulin stimulation and was similar to the wild-type receptor after 30 min of insulin stimulation. However, the mutant receptor was defective in insulin-stimulated tyrosyl phosphorylation of the endogenous substrate pp185. In addition, IR delta 960 was deficient in mediating insulin stimulation of glycogen and DNA synthesis. Thus, autophosphorylation of the insulin receptor is necessary but not sufficient for signal transmission. These data extend the hypothesis that the cytoplasmic juxtamembrane region of the insulin receptor is important for its interactions with ATP, intracellular substrates, and other proteins and is broadly necessary for biological signal transmission.     

Revealing Key Interactions in a Metabolic Network: Model of Primary Phosphate Transport in Bacteria

One of the main problems of metabolic engineering is to determine the genetically controlled limiting links of a metabolic network. We have built a model of the primary transport of inorganic phosphates (P _i ), analyzed the P _i metabolic network in Gram-negative bacteria, and determined the factors controlling the phosphate exchange. The model explains why the P _i primary transport is not observed at the release stage. The nonlinearity of primary transport and the differences in its parameters in the membrane and within the cell give rise to transport asymmetry, i.e., the P _i release rate is low as compared with the uptake rate, and is small at the background of secondary transport. Discussed is a general scheme of coordination between primary and secondary transport, which are interconnected through the substrate–product relation.     

In-vitro formation of a collagenous matrix upon previously diseased and experimentally treated cemental root surfaces

Summary A diseased and mechanically treated surface of root cementum is known, clinically, to favor periodontal regeneration. The present investigation was undertaken to test whether previously diseased and experimentally treated root surfaces can support the in-vitro formation of a new collagenous matrix. Three teeth extracted for advanced periodontitis were treated first with 5% sodium hypochlorite for 2 h to remove all organic material from the root surface. After the healthy, apical one third of the root was cut off, the roots were scaled with moderate pressure to remove visible calculus. Non-demineralized root discs were cut and placed on a co-culture of periodontal ligament- and alveolar bone-derived cells. After 7 weeks in culture, either one of two matrix types was found along the root surface. The most frequent matrix consisted of clusters of cells layered within densely aggregated collagen fibrils. The other, less frequent matrix consisted of loosely arranged collagen fibrils adjacent to the cemental surface. The findings support the notion that, in vitro, a collagenous matrix is formed in contact to diseased and experimentally treated root surfaces. However, the smooth, non-demineralized and scaled cemental surface does not appear to be a suitable substrate for interdigitation with newly produced collagen fibrils.     

Nouvelles observations sur Goniolina hexagona d’Orbigny Algue Dasycladale du Kimméridgien

During a restudy of the type material of Goniolina hexagona d’Orbigny (Kimmeridgian of Charente-Maritime Department, France), reproductive organs of choristosporate type were discovered. This observation induces us to assign Goniolina to the tribe Bornetelleae L. and J. Morellet.