Proclination-induced changes in the labial cortical bone thickness of lower incisors.

OBJECTIVES: We sought to objectivize the overall alveolar bone thickness changes in lower incisors after orthodontic intervention. BACKGROUND: The effect of orthodontic treatment on the cortical bone, specifically the clinical implications of proclination-induced change, have long been a matter of dispute. METHODS: Cone-beam computed tomographs of 58 patients were obtained before and after treatment and labial cortical bone thickness and overall alveolus width were measured in sagittal sections in the distance of 3, 6, 9 and 12 mm apically from the cemento-enamel junction. RESULTS: A statistically significant decrease of the cortical bone thickness in all four incisors was found at the levels 3, 6 and 9 mm (p 0.05). Moreover, no correlation was found between bone thickness change and extent of the incisor movement. CONCLUSION: Our results point to a marked cortical bone loss after proclination of lower incisors, furnishing a sound basis for caution in treatment planning due to the considerable risk of alveolar defect development, especially in patients with low initial bone thickness (Tab. 6, Fig. 2, Ref. 25).

The involvement of phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and MYPT1 isoform expression in NO/cGMP mediated differential vasoregulation of cerebral arteries compared to systemic arteries.

AIM: Constitutive release of NO blunts intrinsic and stimulated contractile activity in cerebral arteries (CA). Here, we explored whether phosphorylation and expression levels of the PKG-sensitive, leucine zipper positive (LZ+ ) splice variants of the regulatory subunit of myosin phosphatase (MYPT1) are involved and whether its expression is associated with higher cGMP sensitivity. METHODS: Vascular contractility was investigated by wire myography. Phosphorylation of MYPT1 was determined by Western blotting. RESULTS: Constitutive phosphorylation of MYPT1-T696 and T853 was lower and that of S695 and S668 was higher in cerebral arteries from the circulus arteriosus (CA-w) than in femoral arteries (FA), while total MYPT1 expression was not different. In CA-w but not in FA, L-NAME lowered phosphorylation of S695/S668 and increased phosphorylation of T696/T853 and of MLC20 -S19, plus basal tone. The increase in basal tone was attenuated in CA-w and basilar arteries (BA) from heterozygous MYPT1-T696A/+ mice. Compared to FA, expression of the LZ+ -isoform was ~2-fold higher in CA-w coincident with a higher sensitivity to DEA-NONOate, cinaciguat and Y27632 in BA and 8-Br-cGMP (1 µmol/L) in pre-constricted (pCa 6.1) α-toxin permeabilized CAs. In contrast, 6-Bnz-cAMP (10 µmol/L) relaxed BA and FA similarly by ~80%. CONCLUSION: Our results indicate that (i) regulation of the intrinsic contractile activity in CA involves phosphorylation of MYPT1 at T696 and S695/S668, (ii) the higher NO/cGMP/PKG sensitivity of CAs can be ascribed to the higher expression level of the LZ+ -MYPT1 isoform and (iii) relaxation by cAMP/PKA pathway is less dependent on the expression level of the LZ+ splice variants of MYPT1.

Electromyographic activity of the respiratory muscles in hyperbaric conditions.

Divers are known to have difficulty breathing in conditions of increased respiratory gas density. This report presents results obtained from electromyographic studies of the inspiratory muscles in conditions imitating a pressure chamber using neon and helium. Electromyographic investigations of the respiratory muscles allows the roles of these muscles in the respiratory act to be assessed and the present study is an attempt to demonstrate the possible neurophysiological mechanisms of respiratory difficulty in high-pressure conditions.

Electromyographic investigations of tremor in aquanauts during simulated immersions.

Electromyographic investigations of tremor in aquanauts under the conditions of stimulated immersions are presented in this paper. The investigations were carried out before the aquanauts entered a barochamber, at specific pressure levels in the barochamber, under the conditions of decompression, and following emergence from the barochamber. The observed manifestations of the tremor under the conditions of increased pressure of trimix exhibited characteristics of parkinsonian tremor.