A preliminary investigation into the microscopic depassivation of passive titanium implant materials in vitro

A sensitive electrochemical technique has been used to examine the passive state of titanium-based materials in Ringer's physiological solution. At ambient temperature, the alloy Ti-6Al-4V shows transient microscopic breakdown of the passive state induced by the presence of chloride ions, and enhanced by increased acidity. These breakdown events involve highly localized depassivation of the passive surface followed by repassivation. Under similar experimental conditions no breakdown of passive titanium was detected.     

Adhesion, growth and differentiation of human bone marrow stromal cells on non-porous calcium carbonate and plastic substrata: effects of dexamethasone and 1,25dihydroxyvitamin D3

Bone marrow contains stromal fibroblastic stem cells which have the potential to differentiate into bone-forming cells. Therefore addition of bone marrow to porous bone substitutes such as coral or coralline hydroxyapatite may be expected to enhance bone ingrowth into these implants. This study was designed to evaluate the possibility of growing human bone marrow stromal fibroblastic cells (HBMC) on a calcium carbonate substrate. For this purpose, HBMC were cultured for 20 days on plastic or calcium carbonate and cell adhesion, growth, and differentiation were studied. It was concluded that calcium carbonate is a highly compatible material for the growth of HBMC. Cells were capable of adhesion within 30 min and were spread within 24 h on this material. However, plating efficiency was decreased in comparison to plastic. Population doubling times (PDT) showed that they were similar when the cells were grown on plastic or calcium carbonate as substratum (PDT=4, 5.5 days). Early protein synthesis included collagen I, collagen III, osteopontin and bone sialoprotein. To induce differentiation of HBMC on plastic and calcium carbonate the influence of dexamethasone (Dex) and 1,25dihydroxyvitamin D3 (1,25(OH)₂D₃) on alkaline phosphatase (ALP) expression was studied. Basic ALP activity was similar when cells were grown on plastic or calcium carbonate. However, Dex and 1,25(OH)₂D₃ increased ALP activity of HBMC which could be driven best towards osteogenesis in the presence of Dex and 1,25(OH)₂D₃.     

RF excitation of a flowing gas CO2 waveguide laser

Investigation of an RF excited CO₂ waveguide laser in flowing gas operation is reported. Power extraction of 0.8 W/cm with an efficiency of 10.3% has been achieved. Using W.W. Rigrod's analysis (1965), values of the small-signal gain α₀ and saturation parameter I_s have been determined for different excitation levels and for different pressures of the amplifying medium. The parameters α₀ and I_s, have been determined as 0.6%/cm and 10.4 kW/cm ², respectively, at 125 torr and 100 W/cm³ RF loading power. These values are close to those reported for sealed-off RF CO₂ waveguide lasers with xenon added to the gas mixture     

Primary biliary cirrhosis: symptoms, laboratory data and diagnosis

The most frequent and important symptoms in primary biliary cirrhosis (PBC) are pruritus and jaundice. In the majority, jaundice appears within one half to two years of onset of pruritus. Xanthoma, bone change and sicca syndrome are often observed. The recent increase in number of asymptomatic PBC is the result of progagation of medical examination. In the biochemical tests, elevation of the biliary enzymes, such as ALP and gamma-GTP, is characteristic, as well as, a high level of serum IgM. Serum bilirubin values are gradually raised along with the clinical course of the disease. Positive antimitochondrial antibody (AMA) is the most valuable immunological finding for the diagnosis of PBC. Anti-pyruvate dehydrogenase complex E2 component E2 has the same significance as AMA. Diagnostic criteria si shown in this paper.     

Impaired stereoacuity due to a lesion in the left pulvinar

A right-handed patient with a haematoma in the left pulvinar showed impaired stereoacuity. In contrast with previous reports, he did not show peripheral visual extinction or prolonged reaction times for targets on the side contralateral to the lesion.     

Cytotoxicity versus antibacterial activity of some antiseptics in vitro

The relationship between endometriosis and infertility is observed frequently. Patients with both conditions require a conservative approach to their management. Since hormonal therapy is one of those approaches, we sought to compare the efficacy of Danazol and Gestrinone in 80 infertile patients (48 and 32, respectively). Therapy lasted 6 months in both treatment groups, and all patients studied had laboratory tests performed and were clinically evaluated and classified through laparoscopy before and after therapy. The improvement of symptoms and favorable follow-up were similar with both treatments. The reestablishment of menstrual patterns and fertility were also nearly alike in both groups. However, Gestrinone was associated with fewer secondary effects and is easier to administer than Danazol. We conclude that Gestrinone is a useful medication in the management of the infertile patient with endometriosis.     

Diagnostics and monitoring of complex production processes using measurement of vibration-acoustic signals

A vibration-acoustic method for diagnostics and monitoring of production processes such as cutting metals makes it possible compared with other methods to reduce the requirement for measuring equipment and it provides a computer representation of the results observed. The set of equipment suggested has low cost and it exhibits considerable flexibility compared with existing equipment. __________ Translated from Izmeritel’naya Tekhnika, No. 7, pp. 30–34, July, 2006.