The positive response of Ty1 retrotransposition test to carcinogens is due to increased levels of reactive oxygen species generated by the genotoxins

In previous laboratory and environmental studies, the Ty1 short-term test showed positive responses (i.e. induced mobility of the Ty1 retrotransposon) to carcinogenic genotoxins. Here, we provide evidence for a causal relationship between increased level of reactive oxygen species and induction the mobility of the Ty1 retrotransposon. Results obtained in concentration and time-dependent experiments after treatment, the tester cells with carcinogenic genotoxins [benzo(a)pyrene, benzo(a)anthracene, ethylmethanesulfonate, formamide], free bile acids (chenodeoxycholic, lithocholic acids) and metals (arsenic, hexavelant chromium, lead) showed a simultaneous increase in both cellular level of the superoxide anions and Ty1 retrotransposition rates. Treatment with the noncarcinogenic genotoxins [benzo(e)pyrene, benzo(b)anthracen, anthracene], conjugated bile acids (taurodeoxycholic, glycodeoxycholic acids) and metals (zinc, trivalent chromium) did not change significantly superoxide anions level and Ty1 retrotransposition rate. The induction by carcinogens of the Ty1 mobility seems to depend on the accumulation of superoxide anions, since the addition of the scavenger N-acetylcysteine resulted in loss of both increased amount of superoxide anions and induced Ty1 retrotransposition. Increased hydrogen peroxide levels are also involved in the induction of Ty1 retrotransposition rates in response to treatment with carcinogenic genotoxins, as evidenced by disruption of YAP1 gene in the tester cells. It is concluded that the carcinogen-induced high level of reactive oxygen species play a primary and key role in determination the selective response of Ty1 test to carcinogenic genotoxins.     

Pixantrone plus rituximab versus gemcitabine plus rituximab in patients with relapsed aggressive B-cell non-Hodgkin lymphoma not eligible for stem cell transplantation: a phase 3, randomized,multicentre trial (PIX306)

PIX306 was a phase 3, randomised, single-blind, multicentre trial conducted in adult patients with diffuse large B-cell lymphoma (DLBCL) or follicular lymphoma (FL) grade 3 who relapsed after ≥1 rituximab-containing regimen and were not eligible for a stem cell transplant. Patients were randomised 1:1 to pixantrone 50 mg/m² or gemcitabine 1000 mg/m² on days 1, 8 and 15 of a 28-day cycle, combined with rituximab 375 mg/m² on day 1, for up to six cycles. Patients were followed for up to 96 weeks. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), complete response (CR) rate, overall response rate (ORR) and safety. Overall, 312 patients were randomised (median age 73·0 years). The study did not meet its primary endpoint. Median PFS [95% confidence interval (CI)] was 7·3 months (5·2–8·4) with pixantrone + rituximab (PIX + R) and 6·3 months (4·4–8·1) with gemcitabine + rituximab [GEM + R; hazard ratio (HR): 0·85; 95% CI 0·64–1·14; P = 0·28]. Median OS was 13·3 (10·1–19·8) months with PIX + R and 19·6 (12·4–31·9) months with GEM + R (HR: 1·13; 95% CI 0·83–1·53). ORR was 61·9% and 43·9% respectively and CR rate 35·5% and 21·7%. The incidence of adverse events, including cardiac events, was not statistically significant different between PIX + R and GEM + R.     

Differential diagnosis between patent foramen ovale and pulmonary arteriovenous fistula in two patients with previous cryptogenic stroke caused by presumed paradoxical embolism.

Development of improved devices for interventional closure of atrial septal defect and patent foramen ovale increased the number of adult patients who are being referred for transcatheter closure. We report two cases that were scheduled for patent foramen ovale closure because of a right-to-left atrial shunt detected at contrast transesophageal echocardiography in another institution and that were found to have pulmonary arteriovenous fistulas. Embolization of pulmonary arteriovenous fistulas was carried out successfully by transcatheter technique.     

Determination of copolymerization parameters in steady state

In the proposed method copolymerization is carried out in an agradient flow reactor where a steady state is established. For the homogenous radical process the following copolymerization equation holds where r₁ and r₂ are the reactivity ratios; a₀, b₀ and a, b are the feed (with index) and steady mole ratios of monomers to an internal standard. Experimentally the relative substance quantities in the reaction system can be measured with the help of gas-chromatography. It is possible to calculate statistically the most probable values for r₁ and r₂ as parameters of the linear form of the above equation. As an example the reaction of styrene and methyl methacrylate in toluene initiated by benzoyl peroxides at 100°C was used. The results are r₁ =0,582±0,044 and r₂ =0,530±0,004; they agree well with literature values.     

Uptake of DNA by fragile mutants of Saccharomyces cerevisiae

Summary When Saccharomyces cerevisiae SY15 rho° mutant cells grown in media stabilized with 10% sorbitol were suspended in 2% sorbitol solutions, 60–70% of the population did not lyse and became permeable to native high molecular weight DNA. Maximal incorporation of DNA to DNase resistant state was measured after 60 min of incubation in presence of 5 g/ml DNA and 10 mM CaCl₂. These results suggest that the fragile mutants might be tested as hosts for transformation of whole yeast cells.     

Capacity flow method for determination of propagation and termination rate constants in radical polymerization

The possibility of determination of the propagation and termination rate constants k_p and k_t, resp., as well as their ratios k_p/k_t and k_p/k in homogeneous radical polymerization is shown using the capacity flow method. A theoretical analysis is carried out and relatively simple equations are introduced. The essential point is that the life time of the growing polymer chain is obtained graphically from the residence time of the reactants in the reactor vessel, which is a given quantity. As an experimental example the polymerization of methyl methacrylate initiated by benzoyl peroxide in benzene is investigated in a flow reactor with perfect mixing at 80°C. It is characteristic that the process can be followed by means usually applied for studying slow reactions. The degree of conversion is measured turbidimetrically and gravimetrically, whereas the initiation rate is analysed iodometrically. Thus, through a numerical linear approximation by the method of least squares k_p/k_t = (2,28±0,45)·10^?5, k_p/k = (1,50±0,22). 10^?1 are found from the experimental data, and hence k^p = (9,95±0,83)·10² l mol^?1 s^?1 and k_t = (4,36±0,49)·10⁷ l mol^?1 s^?1 are obtained.     

Endovascular repair of dissecting thoracic aortic aneurysm in a patient with Turner syndrome.

PURPOSE: To report a rare case of dissecting thoracic aortic aneurysm in a young patient with Turner syndrome owing to complete or partial monosomy of the X chromosome. CASE REPORT: A 22-year-old patient with Turner syndrome presented with a 2-month history of voice loss and dysphagia. Multislice computed tomography (MSCT) disclosed a large (53x75-mm) aneurysm with focal dissection affecting the distal part of the aortic arch and the proximal descending aorta, partially involving the left subclavian artery. A TAG endoprosthesis was implanted without complications. MSCT scans at 3 and 6 months after the procedure showed good position and patency of the stent-graft, with total exclusion and shrinkage of the aneurysm. After 1 year of follow-up, she is doing well, without voice disturbances or dysphagia. CONCLUSION: Although cardiovascular malformations are common in patients with Turner syndrome, dissecting thoracic aortic aneurysm is unusual. Stent-graft repair would appear to be feasible in this situation, but long-term implantation in young patients has not been explored.     

Plasma cyclic 3',5'-adenosine monophosphate in patients with elevated pulmonary pressure due to left-to-right shunt

Background

Increased pulmonary blood flow in patients with left-to-right shunt has been shown to be associated with alterations in prostacyclin-synthesis. There are limited data with respect to the plasma cAMP in patients with elevated pulmonary artery pressure due to left-to-right shunt. We hypothesized that plasma cAMP might be influenced by pulmonary blood flow or pressure in patients with left-to-right shunt.

Methods

Plasma cAMP from venous blood was measured in 122 healthy controls aged 8.3 (0.2 - 14.9) years (median [range]) and in 130 patients with left-to-right shunt aged 1.4 (0.1 - 19.1) years by radioimmunoassay.

Results

Plasma cAMP in controls and in patients was similar and decreased with age. Healthy infants (n = 42) showed higher plasma cAMP (46 [27-112] nmol/l) than children > 6 years of age (n = 40, 39 [19-73] nmol/l; P < 0.001).

Conclusions

These values should be taken into consideration when reporting plasma values for cAMP in patients with congenital heart disease. The values for healthy children obtained in this study should allow a better interpretation of plasma cAMP levels in various disease conditions such as chronic renal failure, liver chirrhosis, hyperthyreosis, or children with intellectual disability.     

Antioxidant defense mechanisms in the lung toxicity of tri-n-butyl phosphate

Pneumotoxic effects of the tri-n-butyl phosphate (TBP) are investigated on rats using biological markers in bronchoalveolar lavage fluid (BALF) and studying key antioxidant enzymes in lung homogenate. Each animal from the experimental group received intratracheally 5 μl TBP (20% v/v in n-dodecane). Six rats from the control and treated groups are sacrificed on post-treatment days 1, 3, 7, 14, and 28. The lactate dehydrogenase activity, the total protein content and the total cell number in BALF are increased mainly on day 1 after the treatment. The activities of superoxide dismutase and catalase are decreased to day 7 and those of glutathione peroxidase and glutathione reductase on day 1 only. The malondialdehyde content is elevated to day 14. It is concluded that TBP causes moderate toxic injury of the lung parenchyma. The depression of the key antioxidant enzymes and the elevated lipid peroxidation are probably important mechanisms of the lung damage. Am. J. Ind. Med. 33:11–15, 1998. © 1998 Wiley-Liss, Inc.     

Associations of serum sclerostin with bone mineral density,markers of bone metabolism and thalassaemia characteristics in adult patients with transfusion-dependent beta-thalassaemia

Abstract

Aim of the study: To assess serum sclerostin in transfusion-dependent beta-thalassaemia patients versus healthy controls and to examine its associations with bone mineral density, bone metabolism markers and beta thalassaemia alterations.

Material and methods: Sixty-two transfusion-dependent beta-thalassaemia (TDßT) patients and 30 healthy controls were evaluated for serum sclerostin, osteocalcin, beta-cross laps, osteoprotegerin and serum level of receptor activator of nuclear factor kappa-Β ligand (sRANKL). Bone mineral density was measured at the lumbar spine and femoral neck. Thalassaemia characteristics were collected from the patients’ medical records.

Results: A significantly higher sclerostin level (median 565.50?pmol/L) was observed in the transfusion-dependent beta-thalassaemia patients vs. the healthy controls (median 48.65?pmol/L, p?<?.001). Sclerostin showed significant associations with the Z-scores at the lumbar spine and femoral neck, osteocalcin, beta-cross laps, osteoprotegerin, sRANKL, pretransfusion haemoglobin, liver iron concentration and female gonadal state. Significantly higher levels of sclerostin were observed in splenectomized TDßT patients and in those with fragility fractures. Age, sex, body mass index, disease severity, serum ferritin, cardiac T2* and male gonadal state did not show significant associations with sclerostin.

Conclusion: Sclerostin may play a role in the bone pathophysiology of beta-thalassaemia patients and could serve as a marker of severe osteoporosis.

• KEY MЕSSAGES

• Serum sclerostin is more than 10-fold higher in adult patients with transfusion-dependent beta-thalassaemia compared to healthy controls.

• Serum sclerostin is negatively associated with bone mineral density and the bone synthesis markers and positively with the bone resorption indices.

• Serum sclerostin is significantly associated with pre-transfusion haemoglobin, liver iron concentration, splenectomy status and fragility fracture events in adult patients with transfusion-dependent beta-thalassaemia.

• Serum sclerostin could serve as a marker of severe osteoporosis in beta-thalassaemia patients.