Comparison Evaluation of the Biological Effects of Sterigmatocystin and Aflatoxin B1 Utilizing SOS-Chromotest and a Novel Zebrafish (Danio rerio) Embryo Microinjection Method

Aflatoxin B1 (AFB1) is a potent mycotoxin and natural carcinogen. The primary producers of AFB1 are Aspergillus flavus and A. parasiticus. Sterigmatocystin (STC), another mycotoxin, shares its biosynthetic pathway with aflatoxins. While there are abundant data on the biological effects of AFB1, STC is not well characterised. According to published data, AFB1 is more harmful to biological systems than STC. It has been suggested that STC is about one-tenth as potent a mutagen as AFB1 as measured by the Ames test. In this research, the biological effects of S9 rat liver homogenate-activated and non-activated STC and AFB1 were compared using two different biomonitoring systems, SOS-Chromotest and a recently developed microinjection zebrafish embryo method. When comparing the treatments, activated STC caused the highest mortality and number of DNA strand breaks across all injected volumes. Based on the E. coli SOS-Chromotest, the two toxins exerted the same genotoxicities. Moreover, according to the newly developed zebrafish microinjection method, STC appeared more toxic than AFB1. The scarce information correlating AFB1 and STC toxicity suggests that AFB1 is a more potent genotoxin than STC. Our findings contradict this assumption and illustrate the need for more complex biomonitoring systems for mycotoxin risk assessment.     

Hand-assisted laparoscopic radical nephrectomy in pregnancy

Purpose

To demonstrate the beneficial results of hand-assisted laparoscopic tumor nephrectomy in pregnancy and to emphasize the proper timing of such surgery for its crucial importance attempting to avoid fatal cancer-related outcomes as a result of late interventions of aggressive tumors.

Methods

A report of a 32-year-old woman with a 61 × 41 mm chromophobe renal cell carcinoma (RCC) successfully treated with laparoscopic transperitoneal hand-assisted nephrectomy during the 20th week of gestation is presented.

Results

The fetus was stable during the intervention; the postoperative period was uneventful; she had a normal vaginal delivery at term and gave birth to a healthy female child. The patient remained tumor-free at her 34-month follow-up.

Conclusion

Although the pure laparoscopic interventions have become recognized in the treatment of RCC over the last decade, these methods have their limitations and dangers as well. The hand-assistance method makes the procedure faster and safer which is especially important during second or third trimester. Renal biopsy may play a specifically important role in predicting the malignant potential of a renal tumor, whereas postponement of this surgery until after delivery, may lead to the mother’s death. To our knowledge, this is the first report on hand-assisted laparoscopic nephrectomy in pregnancy.     

Radiation-induced genomic instability in repair deficient mutants of Chinese hamster cells

Purpose: To determine the role of single (SSB) and double strand break (DSB) repair in the induction and propagation of radiation-induced instability.

Materials and methods: Two defined hamster cell lines with known DNA repair deficiencies in DSB repair (XR-C1) and base excision repair (EM-C11) and the parental wild-type line (CHO-9) were used. The rate of micronucleus formation, apoptosis and survival were measured at 0, 7 and 14 days after X-ray radiation.

Results: An enhanced rate of production of damaged cells was observed in wild type and the repair deficient mutants after irradiation. This was cell type, dose and time-dependent. All cells demonstrated delayed death up to day 14 after irradiation along with an elevated apoptosis frequency. The yield of micronuclei was not significantly increased in the wild-type cells, but was in the mutant cells, over the dose and time range studied. For all three endpoints the increase in damage was most pronounced in the SSB deficient cell line.

Conclusions: SSB and/or oxidized base damage play a major role, rather than DSB, in radiation induced instability.     

Derivation of Power M-Mode Transcranial Doppler Criteria for Angiographic Proven MCA Occlusion

BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.     

L-364,373 fails to activate the slow delayed rectifier K+ current in canine ventricular cardiomyocytes

Activators of the slow delayed rectifier K⁺ current (I_Ks) are promising tools to suppress ventricular arrhythmias originating from prolongation of action potentials. A recently synthesized compound, L-364,373, was shown to activate I_Ks in ventricular cells isolated from guinea pigs and rabbits. Due to the interspecies differences known to exist in the properties of the delayed rectifier K⁺ currents, the effect of L-364,373 on I_Ks was studied and compared with that of another I_Ks activator mefenamic acid in canine ventricular myocytes. Mefenamic acid (100 μM) significantly increased the amplitude of the fully activated I_Ks current, as well as the I_Ks current tails, by shifting the voltage dependence of its activation towards negative voltages and increased the time constant for deactivation. In contrast, L-364,373, up to concentrations of 3 μM, failed to augment I_Ks at any membrane potential studied, but slightly increased the time constant of deactivation. It is concluded that human studies are required to evaluate the therapeutically beneficial effects of I_Ks activators. Rodent cardiac tissues are not suitable for this purpose.     

New methods for the diagnosis of acute pulmonary embolism

INTRODUCTION: Pulmonary embolism is a high mortality cardiovascular disease, which is difficult to diagnose even today. AIM AND METHOD: In this study the symptoms and the results of diagnostic methods were analysed in 81 patients with acute pulmonary embolism, admitted during a one-year period to Kaposi Mór County Hospital. The patient records were examined with special emphasis on the diagnostic value of novel methods such as D-dimer assay and chest computed tomography scanning along with the routine techniques used in the management of pulmonary embolism. RESULTS: In all patients ECG, in 88% of the cases chest X-ray, in 57% blood gas analysis and in 53% D-dimer assay results were evaluated. 14.8% of the patients died during hospitalisation. The following diagnostic imaging procedures were undertaken: in 80.2% of the cases lung scan, in 59.3% echocardiography and in 8.7% of the cases spiral computed tomography scan were prepared. In 12.3% of all cases thrombolysis proved necessary. The results were compared with data from International Cooperative Pulmonary Embolism Registry Study, which analyses 2454 patient cases. CONCLUSION: It is foreseen that the increasing use of echocardiography, lower limb ultrasound and highly informative spiral computed tomography scanning as an additional means in pulmonary embolism diagnostics may in some cases spare the use of pulmonary scintigraphy.     

Gene therapy in pancreatic cancer

Pancreatic cancer is the fifth cause of cancer death in the developed world. It is a highly malignant disease, characterised by aggressive local spread and early locoregional and hepatic metastasis. Surgery offers the only prospect of long-term survival, but the resectability ratio is very low at the time of diagnosis. Conventional chemo- and radiotherapy are relatively ineffective, that is why development of newer therapeutic alternatives are encouraged. Gene therapy came into the limelight of interest. Authors discuss the fundamental scientific principle and clinical experience in connection with gene therapy of pancreatic cancer. Different targets include antisense strategies, gene-replacement, gene-directed prodrug activation therapy, promoter gene strategies, as well as oncolytic viruses.     

Aging and exercise affect the level of protein acetylation and SIRT1 activity in cerebellum of male rats

Aging is associated with a gradual decline in cognitive and motor functions, the result of complex biochemical processes including pre- and posttranslational modifications of proteins. Sirtuins are NAD⁺ dependent protein deacetylases. These enzymes modulate the aging process by lysine deacetylation, which alters the activity and stability of proteins. Exercise can increase mean life-span and improve quality of life. Data from our laboratories revealed that 4 weeks of treadmill running improves performance in the Morris Maze test for young (4 months, old) but not old (30 months, old) male rats, and the exercise could not prevent the age-associated loss in muscle strength assessed by a gripping test. The positive correlation between protein acetylation and the gripping test suggests that the age-dependent decrease in relative activity of SIRT1 in the cerebellum impairs motor function. Similarly to the acetylation level of total proteins, the acetylation of ά -tubulin is also increased with aging, while the effect of exercise training was not found to be significant. Moreover, the protein content of nicotinamide phosphoribosyltransferase, one of the key enzymes of NAD biosynthesis, decreased in the young exercise group. These data suggest that aging results in decreased specific activity of SIRT1 in cerebellum, which could lead to increased acetylation of protein residues, including ά-tubulin, that interfere with motor function.