Evaluation of DNA damage in white blood cells of healthy human volunteers using the alkaline comet assay and the chromosome aberration test

The present study was undertaken to contribute to the characterization of the degree of variability in baseline damage in white blood cells from control population, and to investigate how this variability is associated with external and internal factors. Altogether 170 healthy volunteers, randomly selected from the general population of the Republic of Croatia, participated in the study. Two sensitive tests: the alkaline comet assay and the chromosome aberration test were applied to study the background levels of DNA damage in their white blood cells. The results point to inter-individual differences, indicating different genome sensitivity. As revealed by both assays, the background levels of DNA damage were mostly influenced by smoking habit as well as medical exposure (especially to diagnostic X-rays). Sex and age of subjects did not significantly influence the values of DNA damage recorded in the white blood cells. Although higher levels of DNA damage were recorded in blood samples collected during winter and autumn, they were mostly influenced by medicinal exposure and smoking habit. Statistical evaluation of the data confirmed that a positive correlation exists between DNA migration and the number of long-tailed nuclei found with the comet assay and the total number of chromosome aberrations. The data obtained can serve as control values in forthcoming biomonitoring studies.     

Ribosomal protein S6 gene haploinsufficiency is associated with activation of a p53-dependent checkpoint during gastrulation

Nascent ribosome biogenesis is required during cell growth. To gain insight into the importance of this process during mouse oogenesis and embryonic development, we deleted one allele of the ribosomal protein S6 gene in growing oocytes and generated S6-heterozygous embryos. Oogenesis and embryonic development until embryonic day 5.5 (E5.5) were normal. However, inhibition of entry into M phase of the cell cycle and apoptosis became evident post-E5.5 and led to perigastrulation lethality. Genetic inactivation of p53 bypassed this checkpoint and prolonged development until E12.5, when the embryos died, showing decreased expression of D-type cyclins, diminished fetal liver erythropoiesis, and placental defects. Thus, a p53-dependent checkpoint is activated during gastrulation in response to ribosome insufficiency to prevent improper execution of the developmental program.     

Dietary habits and folate status in women of childbearing age in Croatia

Folic acid and folates have an important role in prevention of neural tube defect that appears in the first weeks of pregnancy, when women are still not aware of their pregnancy, especially when pregnancy is not planned. Since ensuring sufficient quantities of folates and folic acid in this period is essential, dietary habits of childbearing age women are very important. In line with that the intake of folates and folic acid in nutrition of women age group 20-30 years is examined, as well as the frequency of consumption of foodstuffs rich in vitamins and folic acid supplements. Values of folates in serum are presented, dependent on their nutritional habits. Obtained results indicate that in spite of inadequate intake of folates and folic acid from foodstuffs, clinical deficit is not recorded, which is the result of frequent consumption of dietary supplements. In accordance with these dietary habits, differences in the folates status of examinees were observed.     

Prevalence of moderate and severe depression among Croatian patients infected with human immunodeficiency virus

The aim of the study was to assess the prevalence of depression among Croatian patients infected with human immunodeficiency virus (HIV) and to make a comparison with patients with other acute and chronic infectious diseases. We assessed the depressive disorder using the Beck Depression Inventory questionnaire (BDI), without clinical confirmation. The BDI scores were examined in 80 HIV-infected persons and compared to 80 persons with chronic viral hepatitis and 78 with acute infectious diarrhea. All examinees were treated as outpatients at the University Hospital for Infectious Diseases in Zagreb in March and April of 2003. Prevalence of moderate and severe depression among HIV-infected was 16/80 (20%) with a 95% confidence interval 11% to 29%. Male patients with HIV or chronic viral hepatitis had a significantly higher BDI scores than males with acute infectious diarrhea (p = 0.017, Kruskall-Wallis, d.f. 2). Female patients with HIV infection tended to have a lower BDI score than females with chronic viral hepatitis or acute infectious diarrhea (p = 0.087, Kruskall-Wallis, d.f. 2). Prevalence of moderate and severe depression among Croatian HIV-positive patients is higher than the upper estimate for general population. Croatian males with chronic infectious disease have higher rate of depression than those with acute infectious disease.     

Space asymmetry directs preferential sperm entry in the absence of polarity in the mouse oocyte

Knowledge about the mechanism that establishes embryonic polarity is fundamental in understanding mammalian development. In re-addressing several controversial claims, we recently proposed a model in which mouse embryonic polarity is not specified until the blastocyst stage. Before fertilization, the fully differentiated oocyte has been characterized as “polarized,” and we indeed observed that the sperm preferentially enters the polar body half. Here we show that preferential sperm entry is not due to an intrinsic polarity of the oocyte, since fertilization takes place uniformly when the zona pellucida is removed. We suggest that the term “asymmetry” denotes morphological differences, whereas “polarity” in addition implies developmental consequences. Thus, the mouse oocyte can be considered “asymmetric” but “non-polarized.” The penetration through the zona pellucida is also random, and a significant proportion of sperm binds to the oocyte membrane at a point distant from the zona penetration site. Time-lapse recordings confirmed that sperm swim around the perivitelline space before fertilization. Experimental enlargement of the perivitelline space in the non-polar body half increased the regional probability of fertilization. Based on these experiments, we propose a model in which the space asymmetry exerted by the first polar body and the zona pellucida directs sperm entry preferentially to the polar body half, with no need for oocyte polarity.     

Frequency of ventricular premature beats and ventricular tachycardia in STEMI treated with fibrinolytics

To determine in acute myocardial infarction with an ST elevation (STEMI) treated with fibrinolytics frequency of ventricular premature beats (VPBs) and ventricular tachycardia (VT) according to the damaged area and residual cardiac function. With anterolateral infarction with ejection fraction (EF) < 45%, incidence of VPBs < 10/h was statistically significantly reduced (p < 0.001) while incidence of VPBs > or = 10/h as well as VPBs in a pair and VT was increased (p < 0.001). With anteroseptal infarction with EF < 45%, incidence of VPBs < 10/h was statistically reduced (p = 0.06) and incidence of VPBs > 10/h, VPBs in a pair and VT was increased (p = 0.06). With inferior and inferoposterior infarction with EF < 45%, incidence of VPBs < 10/h was reduced and incidence of VPBs > or = 10/h, VPBs in a pair and VT was increased. However, such difference was not statistically significant. Along with reduced residual cardiac function, one can also expect increase in frequency of VPBs and VT in all forms of STEMI regardless the area of damage. Such frequency is significant with all forms of anterior infarction, that is to say, slightly more with anterolateral infarction in relation to anteroseptal one. However, with inferior and inferoposterior infarction this frequency of VPBs i VT is not significant.     

Lost in transition--the Island of Susak (1951-2001)

The isolated population of the Island of Susak was thoroughly studied by a multidisciplinary team of the Croatian Academy of Sciences and Arts in early 1950's. Recently, a team of scientists revisited the island. This paper describes the main characteristics of the transition process during which a massive exodus occurred with 90% of the island's population migrating to New Jersey, USA. We summarise the differences in lifestyle, economy, social structure and sense of identity between the historic (1950's) and contemporary (2001) Susak population. We applied contemporary methods (analysis of microsatellite DNA polymorphisms) to investigate local myths about extreme levels of inbreeding and genetic homogeneity among the Susak islanders. Analysis of short-tandem-repeat (STR) loci showed that Susak displayed characteristics of a small homogeneous breeding isolate. The average heterozygosity was found to be low compared to outbred populations. The signature of a recent severe bottleneck could be detected. Analysis of 8 markers located on Xq13-21 in 71 individuals suggested extensive level of linkage disequilibrium (LD). A migrant study was designed to investigate the effects of large environmental changes (Susak vs. USA) and inbreeding (Susak vs. Croatian general population) on some biologically important quantitative traits, such as blood pressure and serum lipids. The results confirmed the positive correlation between inbreeding level and blood pressure that has been reported in the literature on several occasions. The last remnants of this traditional island community will soon be lost forever.     

The influence of risperidone on cognitive functions in schizophrenia

Introduction of the antipsychotics of the second generation (SGA) into the therapy of schizophrenia roused expectations that, finally, the cognitive dysfunction in schizophrenia could be eliminated by psychopharmacological therapy. The purpose of the study was to verify the effect of atypical antipsychotic risperidone on cognitive functions in schizophrenic patients. The study was carried out upon 48 male schizophrenic patients aged 21-47 years who were switched from the antipsychotics of the first generation (FGA) to the antipsychotic risperidone, due to intolerance, during the treatment. Intelligence, abstract and concrete thinking and mental speed, attention, and short-term non-verbal memory prior to the switch, one month after the switch, and three months after the switch to risperidone, were evaluated. One month after the switch the number of subjects with severe impairment of intellectual abilities decreased significantly from 62% to 15% and after three months the number was even lower-8%. The impairment of concrete and abstract thinking and mental speed also showed the same tendencies of decrease. The improvement of the cognitive functioning after the switch from the antipsychotics of the first generation to the antipsychotic risperidone is explained by removal of the antipsychotics of the first generation from the therapy and the consequential disinhibition of secondary cognitive impairments and by decreased average dose of anticholinergic and decreased number of patients who need anticholinergic therapy beside risperidone. The possibility of clear pro-cognitive effect of risperidone is suggested and its verification is proposed with strict control of other factors that improve cognitive functioning of schizophrenic patients during the treatment.     

Cardiovascular risk factors in a small urban community in central Croatia

The aim of this study was to determine in Karlovac (southern part of central Croatia) the most important risk factors for coronary heart diseases in men and women according to age < or = 59 and > or = 60 on the basis of their prevalence in 558 non-coronary patients and 442 symptomatic coronary patients. In younger male coronary patients (< or = 59 years of age) in relation to the control study, the statistically significant more frequent risk factors were hypercholesterolemia (p < 0.001), smoking (p < 0.01) and diabetes (p < 0.01). In older male patients (> or = 60 years of age) there was no statistically significant difference in a single risk factor. In younger female coronary patients, the statistically significant more frequent risk factors were hypercholesterolemia (p < 0.001) and diabetes (p < 0.001) and in older female patients diabetes (p < 0.05). This population sample showed higher prevalence of cardiovascular risk factors in younger coronary patients. The most frequent risk factors were diabetes, hypercholesterolemia and smoking. The difference is slighter in older coronary patients where it is diabetes, which is the most important for women.     

Lethality of bypass polymerases in Escherichia coli cells with a defective clamp loader complex of DNA polymerase III

Escherichia coli DNA polymerase III (Pol III) is one of the best studied replicative DNA polymerases. Here we report the properties of an E. coli mutant that lacks one of the subunits of the Pol III clamp loader complex, Psi (psi), as a result of the complete inactivation of the holD gene. We show that, in this mutant, chronic induction of the SOS response in a RecFOR-dependent way leads to lethality at high temperature. The SOS-induced proteins that are lethal in the holD mutant are the specialized DNA polymerases Pol II and Pol IV, combined with the division inhibitor SfiA. Prevention of SOS induction or inactivation of Pol II, Pol IV and SfiA encoding genes allows growth of the holD mutant, although at a reduced rate compared to a wild-type cell. In contrast, the SOS-induced Pol V DNA polymerase does not participate to the lethality of the holD mutant. We conclude that: (i) Psi is essential for efficient replication of the E. coli chromosome; (ii) SOS-induction of specialized DNA polymerases can be lethal in cells in which the replicative polymerase is defective, and (iii) specialized DNA polymerases differ in respect to their access to inactivated replication forks.