Conformation of Replicated Segments of Chromosome Fibres in Human S-phase Nucleus

Recent statistical analysis of the folding of G0/G1 chromosomes using fluorescence in situ hybridization (FISH) allowed development of a random walk/giant loop model of chromosome structure. According to this model there are two levels of organization of G0/G1 chromosome fibres. On the first level, the fibres are arranged in giant loops several Mbp in size, and within each loop the fibres are randomly folded. On the second level, the loop attachment sites form a chromosome backbone that also shows random folding. Newly replicated segments of mammalian chromosomes may be directly visualized at high resolution in S-phase nuclei using immunofluorescent methods and appear as worm-like fibres. In our earlier study, we analysed conformation of the fibres in human cells blocked for 16 h at the G1/S boundary with 5- fluorodeoxyuridine (FdU) and then released into S-phase by the addition of a DNA prec ursor. However, long treatment of cells with FdU induces very short replicons and may promote apoptosis. In this study we analysed conformation of the fibres in normally proliferating human cells that had not been blocked with FdU for a long time. It has been found that replicated chromosome fibres visualized just after 2 h of incubation of the cells with a non-radioactively labelled DNA precursor behave as flexible polymer chains without major constraints, and that their local conformation in the range of several microns of their contour length may be considered as random. Confocal analysis of human X chromosomes visualized in HeLa cells using FISH with a specific painting probe shows that in S-phase the chromosomes occupy distinct nuclear territories and their apparent size does not differ from that in non-S-phase cells. This observation indicates that the second level of chromosome organization also exists in S-phase chromosomes. It appears, theref ore, that the random walk/giant loop model developed earlier for G0/G1 chromosomes is also valid for S-phase chromosomes.     

The structure of human S-phase chromosome fibres

Recentin situ hybridization studies suggested that within the range of 0.1–1.0 Mb, human interphase chromosomes follow a random walk model (i.e. they behave as flexible polymers without major constraints). However, chromosome structure may differ in the G1, S, and G2 phases, and phase-specific constraints may be masked if the chromosome analysis does not discriminate between the phases. Therefore, using confocal microscopy, we examined the structure of S-phase chromosomes labelled with 5-iododeoxyuridine after prolonged treatment with 5-fluorodeoxyuridine. In the S-phase, labelled 0.32 µ chromosome fibres mostly appear as semi-circles with an average diameter of 0.83 ±0.03 µ. These semi-circles are joined together to form different 3D structures, and two semicircles frequently adopt s- or-like conformations involving about 2.5 µ of the chromosome contour length (L). Morphometric analysis of the S-phase fibres suggests that our data fit both the random flexible polymer model and also a model in which two constrained semi-circles are attached to each other by a flexible joint, thus eliminating constraints at long distances (L more than 2 µ).     

Toxoplasma gondii: bystander or cofactor in rheumatoid arthritis

Parasitic infections may induce variable immunomodulatory effects and control of autoimmune disease. Toxoplasma gondii (T. gondii) is a ubiquitous intracellular protozoan that was recently associated with autoimmunity. This study was undertaken to investigate the seroprevalence and clinical correlation of anti-T. gondii antibodies in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We evaluated sera from European patients with RA (n = 125) and SLE (n = 164) for the prevalence of anti-T. gondii IgG antibodies (ATXAb), as well as other common infections such as Cytomegalovirus, Epstein-Barr, and Rubella virus. The rates of seropositivity were determined utilizing the LIAISON chemiluminescent immunoassays (DiaSorin, Italy). Our results showed a higher seroprevalence of ATXAb in RA patients, as compared with SLE patients [63 vs. 36 %, respectively (p = 0.01)]. The rates of seropositivity of IgG against other infectious agents were comparable between RA and SLE patients. ATXAb-seropositivity was associated with older age of RA patients, although it did not correlate with RA disease activity and other manifestations of the disease. In conclusion, our data suggest a possible link between exposure to T. gondii infection and RA.     

Hyperferritinemia is Associated with Serologic Antiphospholipid Syndrome in SLE Patients

Ferritin may play a direct role on the immune system. We sought to determine if elevated levels of ferritin in lupus patients correlate with disease activity and organ involvement in a large cohort. Ferritin levels (gender and age adjusted) were assessed in 274 lupus serum samples utilizing the LIASON Ferritin automated immunoassay method. Significant disease activity was determined if European Consensus Lupus Activity Index (ECLAM)?>?2 or Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)?>?4. Utilizing an EXCEL database, we compared elevated ferritin levels to manifestations grouped by organ involvement, serology, and previous therapy. The patients were predominantly female (89%), median age was 37 years old, and disease duration was 10.6?±?7.7 years. Hyperferritinemia was found in 18.6% of SLE patients. Compared to subjects with normal ferritin levels, a significantly greater proportion of patients with hyperferritinemia had thrombocytopenia (15.4% vs. 33.3%, p?=?0.003) and lupus anticoagulant (11.3% vs. 29.0%, p?=?0.01). Additionally, compared to normoferritinemic subjects, hyperferritinemic subjects had significantly higher total aCL (99.7?±?369 vs. 30.9?±?17.3 GPI, p?=?0.02) and aCL IgM antibody levels (75.3?±?357.4 vs. 9.3?±?10.3 GPI, p?=?0.02), and marginally lower aCL IgG antibody levels (9.2?±?4.9 vs. 9.7?±?3.9 GPI, p?=?0.096). While the ECLAM score significantly correlated with hyperferritinemia (p?=?0.04), the SLEDAI score was marginally associated with hyperferritinemia (p?=?0.1). Serositis was marginally associated with hyperferritinemia, but not with other manifestations. An association with serologic APS was encountered. Hyperferritinemia was associated with thrombocytopenia, lupus anticoagulant, and anti-cardiolipin antibodies suggest that it may be an early marker for secondary antiphospholipid syndrome in SLE patients.     

Low birth weight in newborns to women employed in jobs with frequent exposure to organic solvents

The effects of occupational exposure to organic solvents in pregnancy on foetal growth are still unclear. Our aim was to study whether live newborns to women employed in paid jobs with frequent exposure had a different risk of being born with low birth weight (LBW), compared to those of women in jobs without such exposure. The study population was all singleton newborns delivered in the industrial township of Mon?egorsk (N?=?26,415). Information about occupation and characteristics of the mothers and babies was obtained from the local population-based birth register, and registered job function was used to classify exposure. We observed an elevated risk of LBW among live, singleton newborns in the exposed group (adjusted odds ratio: 1.68 [95% CI: 1.18–2.41]), which predominantly consisted of painters. The adjusted odds of LBW in the exposed group were also higher among term-born neonates. In addition, a lower mean birth weight was observed among the exposed.     

Instability of chromosome 6 microsatellite repeats in human cervical tumors carrying papillomavirus sequences

Loss of heterozygosity (LOH) in chromosome 6 in human squamous cervical carcinomas was analyzed in the long and short arms of the chromosome using 3 pairs of primers each. In all cases, normal adjacent tissue was used as control. Among 51 cases analyzed, we identified LOH or microsatellite instability in 23% using primer D6S291 (located at position 6p21.3) and in 11% using primers D6S308 (6q16.3–6q27) and D6S270 (6q22.3–6q23.2). On the contrary, no significant LOH or genomic instabilities were detected with primers D6S306 (6p22.3–6p21.2), D6S299 (6p22.3–6p21.3) and D6S287 (6q21–6q23.3). Our results thus suggest the existence of instable loci at 3 regions of chromosome 6. Whether these loci contain putative tumor-suppressor genes or genes involved in cell cycle control remains unknown. © 1996 Wiley-Liss, Inc.     

The lower level of natural anti-thomsen-friedenreich antigen (TFA) agglutinins in sera of patients with gastric cancer related to ABO(H) blood-group phenotype

The TFA is a tumorassociated, bloodgrouprelated glycosidic precursor structure [Gal(β^1-3)GalNAc]. Its expression in carcinomas is accompanied by a decrease of natural TFA antibodies in serum. The relationship between the ABO(H)-bloodgroup phenotype and natural anti-TFA immune response in patients with gastric cancer was studied. The level of TFA agglutinins in the sera of patients with gastric cancer and of healthy controls was examined by the hemagglutination of neuraminidasetreated bloodgroup-O donor erythrocytes. Individuals were classified as weak or strong TFA responders. They were also classified by ABO(H)-bloodgroup status, age, cancer stage, tumor morphology and level of isohemagglutinins. The proportion of weak TFA responders (WR) in cancer patients was 33, 50, 50 and 20% (for O, A, B and AB blood groups respectively), as compared with 11.7, 14.5, 13.9 and 26.1% for bloodgrouprelated controls. The difference between cancer patients and controls was significant for all blood groups except group AB. Further analysis showed agedependence in bloodgroup-O and -B controls, with a high level of WR in the older group. Bloodgroup-A cancer patients had the greatest and uniform suppression of the level of TFA agglutinins, irrespective of age, cancer stage or tumor morphology, and lower levels of anti-B isohemagglutinins. © 1995 Wiley-Liss, Inc.     

Lifestyle and perceived health in subjects with chronic bronchitis or emphysema: a cross-sectional study

Background  

The study aim was to compare lifestyle behaviors, body mass index (BMI) and perceived health in subjects with and without chronic bronchitis or emphysema, and to explore if these comparisons differed between demographic subgroups.     

Evaluation of magnesium in serum and urine in patients with pulmonary diseases

We evaluated magnesium (Mg) in serum and 24-hour urine in patients with acute and chronic pulmonary diseases. Mg was determined in 114 patients, 56 with acute pulmonary diseases (group I) and 58 patients with acute exacerbation of chronic obstructive pulmonary disease (group II), at the start (To) and at the end of hospital treatment (T1). In group I, in period To, there were disturbances of Mg in serum in 14 patients (25%) which decreased in period T1 and persisted in 4 patients (7.1%) (p < 0.05). In group II the distribution of normal, decreased and increased Mg in serum was similar in periods To and T1 (p > 0.05). Hypomagnesemia was found in 9 patients (16.1%) in group I at the start of treatment (To), with accompanying increased Mg in 24-hour urine in only 4 patients (7.2%). Extrarenal elimination of Mg or transcellular distribution was a possibility. In group II in period To there was a proportional ratio between hypomagnesemia (12-20.7% patients) and increased concentration of Mg in 24-hour urine (20 - 34.5% patients) probably due to renal loss. Simultaneous determination and follow-up of Mg in serum and in 24-hour urine can give information about electrolyte disturbances in acute and chronic pulmonary diseases.     

Membrane fluorescent probes for the demonstration of lymphocyte population heterogeneity. I. T and B lymphocytes of mice and rats

Non-fixed lymphocytes of rats and mice were stained with the membrane fluorescent probe, 3-methoxybenzanthrone. The probe is capable of binding preferentially with lymphocyte membranes and fluoresces in the green spectral region. Microfluorometry of single cells showed that lymphocytes differ in all lymphoid organs and these may be a 3–10-fold variation in fluorescence intensity. Lymphocytes can be divided into two groups according to fluorescence intensity: ‘bright’ and ‘dim’. The proportions of ‘bright’ and ‘dim’ cells were determined in rats and mice for various lymphoid organs in the normal state, after thymectomy and cyclophosphamide treatment, and also after lymphocyte separation on a nylon wool column.In all cases the proportion of bright lymphoctes corresponded to the B-cell content, and the proportion of dim lymphocytes corresponded to the content of T-cells.