Pressure-induced phase transitions in L-alanine, revisited.

The effect of pressure on L-alanine has been studied by X-ray powder diffraction (up to 12.3 GPa), single-crystal X-ray diffraction, Raman spectroscopy and optical microscopy (up to approximately 6 GPa). No structural phase transitions have been observed. At approximately 2 GPa the cell parameters a and b become accidentally equal to each other, but without a change in space-group symmetry. Neither of two transitions reported by others (to a tetragonal phase at approximately 2 GPa and to a monoclinic phase at approximately 9 GPa) was observed. The changes in cell parameters were continuous up to the highest measured pressures and the cells remained orthorhombic. Some important changes in the intermolecular interactions occur, which also manifest themselves in the Raman spectra. Two new orthorhombic phases could be crystallized from a MeOH/EtOH/H(2)O pressure-transmitting mixture in the pressure range 0.8-4.7 GPa, but only if the sample was kept at these pressures for at least 1-2 d. The new phases converted back to L-alanine on decompression. Judging from the Raman spectra and cell parameters, the new phases are most probably not L-alanine but its solvates.

New type of phase transformation in gas hydrate forming system at high pressures. Some experimental and computational investigations of clathrate hydrates formed in the SF6-H2O system.

In this work, we present a new, previously unknown type of structure transformation in the high-pressure gas hydrates, which is related to the existence of two different isostructural phases of the sulfur hexafluoride clathrate hydrates. Each of these phases has its own stability field on the phase diagram. The difference between these hydrates consists of partial filling of small D cages by SF(6) molecules in the high-pressure phase; at 900 MPa, about half of small cages are occupied. Our calculations indicate that the increase of population of small cavities is improbable, therefore, at any pressure value, a part of the cavities remains vacant and the packing density is relatively low. This fact allowed us to suppose the existence of the upper pressure limit of hydrate formation in this system; the experimental results obtained confirm this assumption.

[A new mode of brachial plexus block].

This paper describes a new method of brachial plexus block via subclavian access. The method minimizes the risk of pneumothorax, impairments of nerves and vessels and does not require the use of an electrical stimulator. In addition, it prevents catheter migration during continuous analgesia.

[Kidney autotransplantation in children]. / Autotransplantatsiia pochek u detei.

A total of 4 renal autotransplantations were performed in children in the hospital. The indications for the surgery were ureteric injury (n = 2) and megaloureter associated with distal ureteric stenosis (n = 2). In all cases, autotransplantation was conducted into the ipsilateral iliac fossa after perfusion cooling of the kidney for an average of 28 min. No postoperative complications were observed. There was a complete recovery of renal function in all cases.

[Kidney autotransplantation in ureter injuries and diseases children]. / Autotransplantatsiia pochek pri povrezhdeniiakh i zabolevaniiakh mochetochnika v detskom vozraste.

Six operations for kidney autotransplantation into the ipsilateral iliac fossa were conducted on children aged from 2 to 14 years. In 2 children the operation was performed for a posttraumatic defect in the ureter of a considerable length. Severe neuromuscular dysplasia of the ureter in maintained function of the kidney was the indication for operating on 4 children. No complications occurred in 5 operations. One transplanted kidney had to be removed because of renal artery thrombosis resulting from damage inflicted to the endothelium during washing of the kidney. Operation for autotransplantation of the kidney is a permissible alternative of the traditional methods of replacement or plastics in long posttraumatic strictures and congenital developmental anomalies of the ureter.

[Use of suspended catheters (stents) during surgery of hydronephrosis in children]. / Primenenie podvesnykh kateterov (stentov) pri operatsiiakh po povodu gidronefroza u detei.

The application of hanging catheters (stents) in operations for hydronephrosis in children has considerable advantages over classical (open) methods of drainage. Bacteriological investigations of analyses of urea performed in open and closed closed systems of drainage have shown less incidence of infection of the upper urinary tracts with intrahospital gram-negative flora after operation on patients operated upon with using stents, which gave less amount of postoperative complications.

[Autoimmune nature of spermatogenesis disorders in varicocele models in rats]. / Ob autoimmunnoi prirode narusheniia spermatogeneza pri modelirovanii varikotsele na krysakh.

Partial decrease of venous drainage from the left testis in male rats induced development of destructive changes in the seminiferous epithelium at the site of operation and in the contralateral organ. Spermatogenesis disturbances in the rat testes (focal desquamation of seminiferous epithelium, disorganization and degeneration of germ cells, devastation of seminiferous tubules) resembles the lesion in men with varicocele. These data permit to consider the results of present experiment as varicocele modelling. Disturbance of permeability and of the fine blood-testis barrier structure in both testes was observed in experimental rats; the picture of morphological changes was similar to that of autoimmune orchitis; lymphocytes sensitized to spermatozoa antigens were revealed in the lymphoid organs of experimental rats. The results obtained permit to suggest the involvement of immunological mechanisms in the development of pathological changes in the testes affected with varicocele.