Cytogenetic monitoring of farm animals under conditions of environmental pollution.

Cytogenetic examinations were carried out in 13 cattle farms, two herds of horses, one stag farm and 13 pig farms in areas with different levels of environmental contamination. The frequency of aberrant cells per 100 mitoses was 3.67 +/- 1.89 in pigs (n = 260) and 4.16 +/- 2.4 in herbivores (n = 497). This is a significant difference (p < 0.01). Ten times higher frequencies of chromatid exchanges were found in pigs. The examined herds were classified into three groups by the level of environmental contamination (satisfactory, impaired and severely impaired environment). Significant differences in aberrant cell counts were recorded between the groups of herbivorous animals. Significant differences in pigs were recorded only between herds in satisfactory and severely impaired environments. Significantly higher frequencies of aberrant cells were found in farms of herbivorous animals in the industrial area of Pardubice compared with findings in the South Moravian agricultural area (4.7% and 3.1% respectively). The effect of local contamination sources on farm environment was also investigated. A cattle farm located in the vicinity of a large chemical plant was examined five times at 6-month intervals. An autumn examination revealed significantly higher frequencies of aberrant cells compared with the spring examination.     

Ochratoxin A as the cause of spontaneous nephropathy in fattening pigs.

At a number of slaughters nephropathy and high ochratoxin A contents in kidneys have been observed in fattening pigs from two Swedish farms. In one herd the source of contamination was barley grown on the home farm and stored under such conditions that the growth of fungal species (Penicillium verrucosum var. verrucosum) producing ochratoxin A occurred, with the subsequent formation of the toxin. In this case high ochratoxin A levels in fattening pigs were found during a period of about 18 months. In the second herd, where compounded feed was used, it was impossible to locate the source of contamination. It was presumed that a consignment of feed was damaged by rain during storage at the farm. Ochratoxin A was found in fattening pigs from this herd for a period of about 2 months. Ochratoxin A appeared in the kidneys of all investigated pigs. In some animals the livers, whole blood, and plasma were analyzed, too. The livers contained somewhat lower amounts of ochratoxin A than the kidneys, whereas the content in whole blood and plasma, respectively, was 5 and 13 times greater. Kidneys spontaneously contaminated with ochratoxin A, when stored for 10 months at -70 degrees C, showed no systematic decrease in toxin content.     

Constitutive heterochromatin polymorphism and chromosome damage in viral hepatitis

The frequencies of chromosomal aberrations and sister-chromatid exchanges (SCEs) were scored in relation to constitutive heterochromatin in 100 patients with viral hepatitis B, 100 patients with viral hepatitis A and 100 age- and sex-matched normal controls. 23.4%, 15% and 4% of the cells showed chromosomal aberrations in patients with hepatitis B, hepatitis A and normal controls respectively. Non-random involvement of chromosomal aberrations were also noted in chromosome 1 of patients with hepatitis B and A as compared to normal controls. The frequencies of SCEs (mean +/- S.D.) were found to be 10.40 +/- 2.83 in hepatitis B and 8.70 +/- 2.34 in hepatitis A. These values were significantly higher than the SCE frequency (mean +/- S.D.) of 5.88 +/- 2.25 observed in normal controls (P less than 0.001). The intra-chromosomal distribution of SCEs revealed a relatively increased incidence of SCEs in chromosome 1 of patients with hepatitis B and A as compared to normal controls. Analysis of constitutive heterochromatin polymorphism showed chromosome 1 qh+ to be the most frequent variant in patients with hepatitis B and A as compared to normal controls. The increased involvement of C-band variant 1 qh+ in patients with hepatitis B and A as compared to normal controls may indicate that extra heterochromatin offers additional sites for viral integration.     

Hypersensitive character of Bloom syndrome B-lymphoblastoid cell lines usable for sensitive carcinogen detection

Various carcinogens were tested with regard to the induction of sister-chromatid exchanges (SCEs) and chromosome aberrations using 3 types of Bloom syndrome (BS) B-lymphoblastoid cell lines (LCLs) (type I with normal frequency of SCEs and normal karyotype; type II with high frequency of SCEs and normal karyotype; type III with high frequency of SCEs and abnormal karyotypes) in the presence and absence of S9 mix. Three types of BS B-LCLs and normal cells showed different responses to the various carcinogens in the level of SCE induction. BS type I cells had the same SCE response as normal cells to carcinogens. Some carcinogens that require metabolic activation (S9 mix) had little effect on type II cells without S9 mix but had high SCE levels with S9 mix. BS type III cells were highly susceptible to both direct and indirect carcinogens with respect to high SCE increase without S9 mix (ca. 140 SCEs/cell), though some carcinogens produced SCEs rated in the medium (ca. 120 SCEs/cell) range, and had a high rate (more than 10%) of centromere spreading (CS), in addition to quadriradials. Therefore BS type III is a unique cell line which can be used to detect carcinogens.     

Cytogenetic analysis of peripheral blood lymphocytes in glass workers occupationally exposed to mineral oils

Chromosome aberration tests were carried out in a group of 31 pressed glass makers operating an automatic line of press-and-blow machines known to release mineral oil mists containing relatively high concentrations of the mutagenic chemicals belonging to a class of polycyclic aromatic hydrocarbons (PAH). The workers were exposed to the mineral oil aerosol levels that did not exceed the Czechoslovak maximum allowable concentration limit of 5 mg . m-1 of air. The tests revealed that the frequency of aberrant cells (% AB.C.) and the value of breaks per cell (B/C) ratio found in mineral oil-exposed workers were increased significantly, accounting for 4.65 +/- 0.29% AB.C. (0.0532 B/C) vs. 1.13 +/- 0.19% AB.C. (0.0113 B/C) seen in matching controls. Also, a higher rate of dicentrics, reciprocal translocations and cells with pulverization was observed in this group of glass workers. These finding are considered as evidence suggesting that these workers might experience an increased risk of genetic injury due to exposure to mineral oil mists.     

Cytogenetical characterization of Chinese hamster ovary X-ray-sensitive mutant cells, xrs 5 and xrs 6. IV. Study of chromosomal aberrations and sister-chromatid exchanges by restriction endonucleases and inhibitors of DNA topoisomerase II

Induction of chromosomal aberrations and sister-chromatid exchanges (SCEs) was studied in wild-type Chinese hamster ovary (CHO-K1) cells and its 2 X-ray-sensitive mutants xrs 5 and xrs 6 (known to be deficient in repair of DNA double-strand breaks (DSBs] by restriction endonucleases (REs) and inhibitors of DNA topoisomerase II known to induce DNA strand breaks. Five different types of REs, namely CfoI, EcoRI, HpaII (which induce cohesive DSBs), HaeIII and AluI (which induce blunt DSBs) were employed. REs that induce blunt-end DNA DSBs were found to be more efficient in inducing chromosomal aberrations than those inducing cohesive breaks. xrs 5 and xrs 6 mutants responded with higher sensitivity (50-100% increase in the frequency of aberrations per aberrant cell) to these REs than wild-type CHO-K1 cells. All these REs were also tested for their ability to induce SCEs. The frequency of SCEs increased in wild-type as well as mutant CHO cells, the induced frequency being about 2-fold higher in xrs mutants than in the wild-type cells. We also studied the effect of inhibitors of DNA topoisomerase II, namely 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) and etoposid (VP 16), at different stages of the cell cycle of these 3 types of cells. Both drugs increased the frequency of chromosomal aberrations in G2 cells. The mutants showed increased sensitivity to m-AMSA and VP 16, xrs 6 cells being 10- and 2-fold more sensitive than wild-type CHO-K1 cells respectively, and xrs 5 responding with 2-fold higher sensitivity than xrs 6 cells. G1 treatment of CHO cells with m-AMSA increased both chromosome- and chromatid-type aberrations, xrs mutants being about 3-fold more sensitive than CHO-K1 cells. The frequency of SCEs increased also after treatment of exponentially growing and S-phase CHO cells with m-AMSA and the higher sensitivity of xrs mutants (2-fold) was evident. The S-phase appeared to be a specific stage which is most prone for the induction of SCEs by m-AMSA. The results indicate that DNA DSBs induced by REs and inhibitors of DNA topoisomerase II correlate closely with induced chromosomal aberrations and SCEs in these cell lines, indicating that DSBs are responsible for the production of these 2 genetic endpoints.     

Cytological characterization of Chinese hamster ovary X-ray-sensitive mutant cells, xrs 5 and xrs 6. II. Induction of sister-chromatid exchanges and chromosomal aberrations by X-rays and UV-irradiation and their modulation by inhibitors of poly(ADP-ribose) synthetase and alpha-polymerase

The cell killing and induction of sister-chromatid exchanges (SCEs) by X-rays and short-wave ultraviolet (UV) irradiation in combination with inhibitors of DNA repair, 3-aminobenzamide (3AB), cytosine arabinoside (ara-C) or aphidicolin (APC) were studied in wild-type CHO-K1 and two X-ray-sensitive mutants, xrs 5 and xrs 6 cells. The spontaneous frequency of SCEs was similar in the mutants and the wild-type CHO-K1 cells (8.4-10.3 SCEs/cell). Though X-rays are known to be poor inducers of SCEs, a dose-dependent increase in the frequency of SCEs in xrs 6 cells (doubling at 150 rad) was found in comparison to a small increase in xrs 5 and no increase in wild-type CHO-K1 cells. 3AB, an inhibitor of poly(ADP-ribose) synthetase increased the spontaneous frequency of SCEs in all the cell types. 3AB did not potentiate the X-ray-induced frequency of SCEs in any of the cell lines. Ara-C, an inhibitor of DNA polymerase alpha, increased the frequency of SCEs in all the cell lines. In combined treatment with X-rays, ara-C had no synergistic effect in xrs 5 and xrs 6 cells, but the frequency of SCEs increased in X-irradiated wild-type CHO-K1 cells post-treated with ara-C. For the induced frequency of SCEs, CHO-K1 cells treated with X-rays plus ara-C behaved like xrs 6 cells treated with X-rays alone, suggesting a possible defect in DNA base damage repair in xrs 6 cells, in addition to the known defective repair of DNA double-strand breaks (DSBs). Survival experiments revealed higher sensitivity of xrs 5 and xrs 6 mutant cells to the cell killing effect of X-rays in S-phase when compared to wild-type CHO-K1 cells. The mutants responded with lesser sensitivity to cell killing effect of ara-C and APC than CHO-K1 cells, the relative sensitivity to ara-C or APC being CHO-K1 greater than xrs 5 greater than xrs 6 cells. When X-irradiation was coupled with ara-C, the results obtained for survival were similar to those of the SCE test, i.e., unlike wild-type CHO-K1, no synergistic effect was observed in xrs 5 or xrs 6 cells. After UV-irradiation, the frequency of SCEs increased similarly in wild-type CHO-K1 and xrs 6 cells, but xrs 5 cells responded with lower frequency of SCEs.(ABSTRACT TRUNCATED AT 400 WORDS)     

Spontaneous and induced sister chromatid exchanges in the blood lymphocytes of healthy persons and of xeroderma pigmentosum patients exposed to the inhibitors of DNA repair and replication caffeine, 3-methoxybenzamide and novobiocin

The frequency of sister chromatid exchanges (SCEs), both spontaneous and induced by UV-light, X-rays, mitomycin C and ethylmetansulphonate (EMS), has been investigated in cultured human peripheral blood lymphocytes. Besides, frequency of spontaneous and induced SCEs was studied under the action of the inhibitors of topoisomerase II, polymerase poly(ADP-ribose), and DNA repair, i. e. novobiocin, 3-metoxybenzamide, and caffeine, respectively. It is shown that the base-line SCEs in lymphocytes of the patient with xeroderma pigmentosum II (XP2LE) is dramatically higher compared to that in normal and pigmented xerodermoid cells (XP3LE). The above inhibitors of DNA synthesis and repair enhance the rate of spontaneous SCEs in normal, XP2LE and XP3LE cells. UV-, X-ray and chemical mutagens induced an increased frequency of SCEs in these cells. Simultaneous treatment with mutagenes and inhibitors of DNA synthesis and DNA repair enhanced the rate of SCEs in lymphocytes of healthy donors and in the XP3LE patient. The frequency of the XP2LE cells. Novobiocin, 3-MBA and caffeine significantly decreased the frequency of SCEs in mitomycin C- and EMS-treated XP2LE lymphocyte, which nevertheless was much higher than that in normal cells treated with the same agents.     

Cytogenetic studies on blood lymphocytes from patients with Schistosoma mansoni

Chromosomal aberrations and sister chromatid exchange (SCE) frequencies were studied in peripheral blood lymphocytes from 10 patients with Schistosoma mansoni prior to initiation of chemotherapy. The mean frequencies of chromatid and chromosome breaks for the patients were 1.80 and 2.30%, respectively, which were significantly higher (P less than 0.01) than the means 0.35 and 0.30%, scored for 20 healthy controls. Significant increase in the mean frequency of SCEs in the patients (9.1 +/- 0.5 SCE/cell) was noticeable when compared with the controls (6.2 +/- 0.1 SCEs/cell). Reductions in the lymphocyte divisions and replications in the patients were also observed. These results indicate that infection with S. mansoni could have in vivo mutagenic effects on human chromosomes.     

The numbers and distribution of buffalo in the Ruwenzori National Park*, Uganda

The buffalo (Syncerus coffer (Sparrman)) in the Ruwenzori National Park, Uganda were censused by means of aerial survey. Details of earlier censuses of buffalo from the air are given. Herds were located by flying along flight lines 1–6 km apart at a height of 300 m above ground. Buffalo in small herds and in bachelor groups containing less than thirty animals were counted individually but most herds were photographed and the number of buffalo counted from the prints. Two full photographic counts were made in November 1968 and December 1969 and subsequently, counts of herds only were made four times a year during each wet and dry season. The total numbers of buffalo were estimated from the herd counts on the basis of the mean herd size and percentage of bachelors recorded earlier. A total of 17 835 buffalo, comprising 16 749 in 165 herds and 1086 bachelor bulls, was recorded in 1968 and 18 040 buffalo made up of 17 141 in 162 herds and 899 bachelors were counted in 1969. The mean herd size was 101-5 in 1968 and 105-8 in 1969 with bachelors representing 6-1% and 5-0% of the totals in 1968 and 1969 respectively. The mean size of the bachelor groups was 4–7 and 3-3 in 1968 and 1969 respectively. The density of the buffalo was the same each year at twelve animals per sq. km. If only the preferred habitat is considered, the density becomes thirty-eight buffalo per sq. km. The mean areas occupied by a single herd were 9-4 and 9-6 sq. km in 1968 and 1969 respectively. The mean area of preferred habitat used by one herd was 2–9 sq. km each year. It is concluded that herd counts are not a satisfactory method for assessing the total buffalo population although they have value as indices, provided the same observer is used. However, they do suggest in the present work that there is a slight but definite seasonal movement of buffalo into forested areas or towards permanent water during the dry season.     

Cytological characterization of repair-deficient CHO cell line 43-3B. I. Induction of chromosomal aberrations and sister-chromatid exchanges by UV and its modulation with 3-aminobenzamide

The induction of chromosomal aberrations and sister-chromatid exchanges (SCEs) by short-wave ultraviolet (UV) and X-irradiation was studied in Chinese hamster ovary (CHO) wild-type (WT) cells and one of its UV-hypersensitive mutants, 43-3B. The results indicate that CHO 43-3B show high levels of spontaneously occurring chromosomal aberrations and SCEs; these levels are, respectively, approximately 4 and 1.7 times those found in WT CHO. Treatment with UV produced a considerable delay in the cell-cycle progression of the mutant cells compared to the WT cells. Doses of UV that had no effect on WT cells, significantly induced chromosomal alterations in the mutant in a dose-dependent manner. An approximately 5-fold increase in the induced frequencies of SCEs was obtained in 43-3B cells after UV treatment. No synergistic effect was observed with UV irradiation and the inhibitor of poly(ADP-ribose) synthetase, 3-aminobenzamide (3AB), in either cell type. The frequency of SCEs in the mutant cell lines was lower than would be expected if the effects of UV and the inhibitor were additive. X-Ray alone in G1 and in combination with 3AB in G2 did not induce increased frequencies of chromosomal aberrations in mutant cells in comparison to the WT cells.     

Culling intervals and culling risks in four stages of the reproductive life of first service and reserviced female pigs in commercial herds

The objectives of this study were to measure culling intervals and culling risks in the four stages of the reproductive life of female pigs and to compare culling intervals between the number of services and between herd groups, based on herd productivity. We also compared survival patterns of females pigs between these herd groups. Our data set included lifetime records of 52,792 females born between 2001 and 2004 in 101 commercial herds. Two herd groups were selected on the basis of the upper 25th percentile of pigs weaned per mated female per 5 yr between 2002 and 2006, namely the high-performing herds, and ordinary herds. Culled females were also allocated into four groups based on the stages of their reproductive life when culled: unmated gilts, mated gilts, unmated sows, and mated sows. Culling intervals in unmated gilts and mated gilts were defined as the number of days from birth to culling and from first mating to culling, respectively. Culling intervals in unmated sows and mated sows were the number of days from weaning to culling. The number of services was categorized into two groups: first service and reservice groups. Multilevel linear mixed-effects models and survival analysis were performed. Culling intervals (±SEM) in unmated gilts, mated gilts, unmated sows, and mated sows were 302.9 ± 1.16, 98.4 ± 0.92, 14.3 ± 0.12, and 89.6 ± 0.42 d, respectively. Culling risks in the four groups were 5.6%, 7.1%, 58.0%, and 29.3%, respectively. In unmated gilts, mated gilts, and mated sows, the culling intervals in the high-performing herds were 43.0, 18.9, and 16.0 d shorter than those in ordinary herds, respectively (P < 0.05), but no difference was found between the herd groups for the culling interval of unmated sows. For mated sows in the reservice group, culling intervals of high-performing herds were ≥13.7 d shorter than those of the ordinary herds (P < 0.05), but for mated sows in the first service group, there was no difference in the culling interval between the herd groups. The culling hazard from 8 wk postweaning for mated sows in high-performing herds increased more rapidly than that in ordinary herds. In conclusion, to reduce culling intervals and improve herd productivity, we recommend implementing a strict culling policy for mated gilts and mated sows, especially reserviced females.     

Chromosomal aberrations and sister chromatid exchanges in individuals exposed to arsenic through drinking water in West Bengal,India

Arsenic contamination in groundwater has become a worldwide problem. Currently an unprecedented number of people in West Bengal, India and Bangladesh are exposed to the ubiquitous toxicant via drinking water in exposure levels far exceeding the maximum recommended limit laid down by WHO. This arsenic epidemic has devastated nine districts of West Bengal encompassing an area of 38,865 km(2) leading to various clinical manifestations of chronic arsenicosis. We conducted a human bio-monitoring study using chromosomal aberrations (CA) and sister chromatid exchanges (SCE) as end points to explore the cytogenetic effects of chronic arsenic toxicity in the population of North 24 Parganas, one of the arsenic affected districts in West Bengal. Study participants included 59 individuals residing in this district where the mean level (+/-S.E.) of arsenic in drinking water (microg/l) was 211.70+/-15.28. As age matched controls with similar socio-economic status we selected 36 healthy, asymptomatic individuals residing in two unaffected districts--Midnapur and Howrah where the mean arsenic content of water (microg/l) was 6.35+/-0.45. Exposure was assessed by standardized questionnaires and by detecting the levels of arsenic in drinking water, nails, hair and urine samples. In the exposed group the mean arsenic concentrations in nails (microg/g), hair (microg/g) and urine (microg/l) samples were 9.04+/-0.78, 5.63+/-0.38 and 140.52+/-8.82, respectively, which were significantly high (P<0.01) compared to the corresponding control values of 0.44+/-0.03, 0.30+/-0.02 and 5.91+/-0.49, respectively. Elevated mean values (P<0.01) of the percentage of aberrant cells (8.08%) and SCEs per cell (7.26) were also observed in the exposed individuals in comparison to controls (1.96% and 5.95, respectively). The enhanced rates of CAs and SCEs among the residents of North 24 Parganas are indicative of the cytogenetic damage due to long term exposure to arsenic through consumption of contaminated water.     

Indirect mutagen assay in human lymphocyte in the presence of a metabolic activation system

Chromosome aberrations in cultured human lymphocytes were examined after exposures to various concentrations (from 1 X 10(-6) to 1 X 10(-3) mol X l-1) of cyclophosphamide (CP) in the presence or absence of a metabolic activation system (S9 mix). With metabolic activation, increases in the frequency of aberrant cells (AB. C.) produced by CP were significant and dose-dependent. At a concentration of 5 X 10(-4) mol X l-1, activated CP induced 29% AB. C. versus 6% AB. C. detected after exposures to CP without metabolic activation. The freshly prepared S9 mix did not virtually differ in its activation potency from the S9 mix stored for 3 weeks at -20 degrees C. CP preincubated for 100 min with S9 mix caused little or no increase in AB. C. frequency above the control level.     

Chromosomal abnormalities in soft coal open-cast mining workers

Chromosome aberration tests on cultured peripheral blood lymphocytes were carried out in two groups of open-cast mining workers engaged in stripping operations (Group I) and digging operations (Group II), in a group of coal cleaning plant workers used as a positive control, and in a group of nonexposed subjects serving as matching controls. Peripheral blood samples in group I and group II miners were collected in March and June of 1984, the antimutagenic potential of long-term prophylactic vitamin administrations (1 g of ascorbic acid given daily for a period of 3 months and 100 mg of vitamin A a day for two 5-day cycles) initiated after the first blood sampling was tested in group II miners. The frequency of aberrant cells (% AB.C.) found in the cultured lymphocytes of group I miners was increased at both times of measurement (2.41% AB.C. and 2.29% AB.C.), in group II miners given the vitamin prophylaxis it dropped significantly (P greater than 0.01) from the initial 3.16% AB.C. in March to 1.77% AB.C. in June, and in the group of coal cleaning plant workers (1.30% AB.C.) it was more or less equal to that of matching controls (1.21% AB.C.). Implicitly, coal dust alone can hardly be made responsible for the rise in % AB.C. It appears that the increase in frequency of chromosome aberrations observed in soft coal open-cast mining workers rather reflects an increased risk of genetic injury due to exposure to ever-present fumes and fire hazards that may give rise to the mutagenic chemicals belonging to a class of polycyclic aromatic hydrocarbons. The antimutagenic effect of ascorbic acid prophylaxis was characterized by a significant drop in % AB.C. and a speed-up of the lymphocyte cell cycle expressed as the proliferating rate index (PRI) whose value rose from the original 1.41 to 1.69, thus reaching the PRI value of matching controls (1.63).     

Boar culling and mortality in commercial swine breeding herds

The objectives of this study were to measure culling rate and mortality rate of boars; to compare boar life day (BLD: days from birth date to removal date), boar herd life day (BHLD: days from herd entry date to removal date) and herd entry age of boars between high-performing herds and ordinary herds (herd groups); to examine herd measurements for BLD, BHLD and boar age at herd entry; and to observe removal patterns and survival curves for boars by herd groups. This study used 2474 records of individual boars born in 108 herds from 2000 to 2003. Two herd groups were formed on the basis of the upper 25th percentile of pigs weaned per mated female per year (2001-2005). Mixed-effects models and survival analysis were performed. Means of BLD and BHLD (±S.E.M.) were 984 ± 9.5 and 781 ± 8.4 d, respectively. Annualized culling rate and mortality rate were 0.411 and 0.035 boars per 365 BHLD, respectively. Boars in high-performing herds had 51 higher BLD and 62 higher BHLD than those in ordinary herds (P < 0.01). High-performing herds had 32 d lower entry ages than ordinary herds (P < 0.01). Herd measurements such as herd mortality and herd size were not associated with both BLD and BHLD. The hazards in survival analysis were associated with herd groups (P < 0.05). Measurements in the present study provide benchmarks for boar removal in commercial herds.     

Porcine reproductive and respiratory syndrome virus (PRRSV) in GB pig herds: farm characteristics associated with heterogeneity in seroprevalence

Background

The between- and within-herd variability of porcine reproductive and respiratory syndrome virus (PRRSV) antibodies were investigated in a cross-sectional study of 103 British pig herds conducted 2003–2004. Fifty pigs from each farm were tested for anti-PRRSV antibodies using ELISA. A binomial logistic model was used to investigate management risks for farms with and without pigs with PRRSV antibodies and multilevel statistical models were used to investigate variability in pigs' log ELISA IRPC (relative index × 100) in positive herds.

Results

Thirty-five herds (34.0%) were seronegative, 41 (39.8%) were seropositive and 27 (26.2%) were vaccinated. Herds were more likely to be seronegative if they had < 250 sows (OR 3.86 (95% CI 1.46, 10.19)) and if the nearest pig herd was ≥ 2 miles away (OR 3.42 (95% CI 1.29, 9.12)). The mean log IRPC in seropositive herds was 3.02 (range, 0.83 – 5.58). Sixteen seropositive herds had only seropositive adult pigs. In these herds, pigs had -0.06 (95% CI -0.10, -0.01) lower log IRPC for every mile increase in distance to the nearest pig unit, and -0.56 (95% CI -1.02, -0.10) lower log IRPC when quarantine facilities were present. For 25 herds with seropositive young stock and adults, lower log IRPC were associated with isolating purchased stock for ≥ 6 days (coefficient -0.46, 95% CI -0.81, -0.11), requesting ≥ 48 hours 'pig-free time' from humans (coefficient -0.44, 95% CI -0.79, -0.10) and purchasing gilts (coefficient -0.61, 95% CI -0.92, -0.29).

Conclusion

These patterns are consistent with PRRSV failing to persist indefinitely on some infected farms, with fadeout more likely in smaller herds with little/no reintroduction of infectious stock. Persistence of infection may be associated with large herds in pig-dense regions with repeated reintroduction.

     

Differential sensitivity of peripheral blood lymphocytes of untreated leprosy patients to mitomycin C

The effects of a bifunctional alkylating agent mitomycin C (MMC), an effective inducer of chromosome aberrations and sister-chromatid exchanges (SCEs), have been studied in untreated leprosy patients. This was done to study the mutagen sensitivity of the leprosy patients. The frequency of chromosomal aberrations induced by MMC (conc. 0.01 microgram/ml) was 2.5% in controls, 3.6% in paucibacillary (PB), and 6.8% in multibacillary (MB) patients. The difference in the frequency of MMC-induced chromosome aberrations between the 3 groups studied was highly significant (p less than 0.01). Cultures grown with MMC showed the frequency of SCEs/cell to be 12.70 +/- 1.19 in controls, 19.97 +/- 3.51 in PB, and 29.66 +/- 5.92 in MB patients. The differences in the frequency of MMC-induced SCEs between the 3 groups were found to be highly significant (p less than 0.01). The enhanced frequencies of spontaneous and MMC-induced chromosome aberrations and SCEs observed in PB and MB patients indicate a clear differential mutagen sensitivity between PB and MB patients who are known to have different immunological status and thereby differ in the severity of the disease.     

Possible genetic damage in the Czech nuclear power plant workers

The aim of our study was to identify occupational risk of irradiation exposure in the Czech nuclear power plant workers. We analyzed levels of chromosomal aberrations, a well-known biomarker of early biological effects and a predictor of cancer risk. We applied the conventional method of cytogenetic analysis and fluorescence in situ hybridization (FISH, whole chromosome painting for chromosomes 1 and 4, combined with a pancentromeric probe) to three groups: 123 subjects in the Temelin nuclear power plant (2 years in use), 114 subjects in the Dukovany nuclear power plant (20 years in use), and 53 matched controls from Ceske Budejovice. Nuclear power plant workers were divided into two groups: subjects with admittance into the monitored zone, and others. Following factors were also analyzed: GSTM1, GSTT1, GSTP1, XPD, XRCC1, hOGG1, p53, MTHFR, and MS gene polymorphisms, levels of vitamins A, C, E, and folate in plasma, and level of cotinine in urine. Long-term exposure to ionizing radiation in the monitored zone was 0.47+/-1.50 mSv (miliSievert) in the Temelin nuclear power plant and 5.74+/-9.57 mSv in the Dukovany nuclear power plant. Using the conventional cytogenetic analysis, we observed 1.90+/-0.95 and 1.82+/-1.19% AB.C. (percent of aberrant cells) in the Temelin nuclear power plant, and 2.39+/-1.01 and 2.33+/-1.04% AB.C. in the Dukovany nuclear power plant, for monitored zone workers and others, respectively. In the control group, we found 2.25+/-0.82% AB.C. Genomic frequency of translocations F(G)/100 measured by FISH was 1.89+/-1.40 and 2.01+/-1.68 in the Temelin nuclear power plant, and 2.48+/-1.93 and 2.14+/-1.62 in the Dukovany nuclear power plant for monitored zone workers and others, respectively. In the control group, F(G)/100 was 1.83+/-1.19. Following factors were identified as potential confounders by the conventional cytogenetic analysis: XPD-6, by the FISH: age, GSTP1 and p53Bst genotypes, long-term use of medication, alcohol consumption, and smoking. No association between the dose of irradiation and the level of chromosomal aberrations in any nuclear power plant was detected either by the conventional cytogenetic analysis or by FISH.     

Postpartum Reproductive Performance in Dairy Cows in Relation to Phosphorus Status

The levels of inorganic phosphorus in blood samples from two cow populations were related to reproductive performance. Group I comprised 305 dairy cows from 17 herds with normal fertility. The herds were visited every 2–4 weeks. Blood samples were collected from animals between 4 weeks prior to expected calving and subsequent confirmed pregnancy. The individual mean plasma phosphorus level in samples collected from 0–90 days after calving in cows which conceived following insemination (n = 262) was related to reproductive performance. Group II comprised cows from 47 herds with reproductive problems. The herds were visited once during the indoor season for blood sampling. Mean herd serum phosphorus levels were related to herd reproductive performance registered during a period from 6 months before to 9 months after the time of blood sampling. Overall mean herd phosphorus levels were 1.51 ± 0.08 mmol/1 plasma (±SD) (Group I) and 1.77 ± 0.16 mmol/1 serum (±SD) (Group II). In Group I (indivu-dual cows), the coefficient of correlation between phosphorus levels and elapsed time from calving to pregnancy was low (r = 0.10, p<0.1). In Group II (herds) significant correlations were observed between the fertility status index (FS), the average number of days from calving to last insemination and phosphorus levels (rs = 0.32, P <0.05 and rs p <0.05, respectively). The mean herd phosphorus levels were within normal limits in both groups. Although increased phosphorus levels were associated with lower fertility in both groups, the amount of the total fertility variation which could be explained by phosphorus levels was small.