[Clostridium colitis at a surgical department]. / Problematika klostridiové kolitidy na chirurgickém pracovisti.

INTRODUCTION: The aim of our study was to identify risk factors associated with the development of Clostridium difficile colitis and determining the severity of clostridial colitis in a group of surgical patients. Identification of its predispositions is necessary for preventive interventions and effective treatment. MATERIAL AND METHODS: 51 patients diagnosed with clostridial colitis were included in our study. The inclusion criterion was based on laboratory detection of clostridial toxin in each patient. We analysed age, concomitant malignancy, recent surgical intervention, antibiotic and proton pump inhibitors treatment. The severity of clostridial colitis and its correlation to possible risk factors mentioned above was described and statistically evaluated. Non-parametric Fischer test was used for the statistical evaluation. RESULTS: We confirmed the importance of potential risk factors in the evaluated group of surgical patients with Cl. difficile colitis. The course of the disease was described as serious in 39.2% of patients in the study group. Recurrent attack of colitis was diagnosed in 4 patients, in 2 of them the second recurrence, in 1 patient the third relapse occurred. 2 patients with clostridial colitis evaluated in our group died, but the relation of their death to the clostridial GIT infection was not causal and the primary cause of death in both of them was multiple organ failure caused by serious comorbidities. We did not indicate any surgical intervention and no toxic megacolon developed in our study group. We did not detect any statistical correlation between the described risk factors and the severity of colitis. CONCLUSION: Clostridium difficile colitis needs to be recognised as a serious complication, especially in hospitalised patients. Its increased frequency and severity should not be underestimated. Although we can identify potential risk factors, we cannot exclude some of them completely (e.g. antibiotic and PPI treatment). On the other hand, a rational approach to antibiotic treatment in particular can be helpful in reducing the frequency and severity of clostridium difficile colitis.

Physical fitness in lignite miners.

The purpose of this study was to determine physical fitness level of lignite miners in the Czech Republic. The authors have examined a representative group of 152 active lignite miners by bicycle spiroergometry. The duration of employment in coal mines ranged between 5 and 32 years. The average age was 43.1 +/- 4.7 years. The miners had an average peak oxygen consumption 2.9 +/- 0.5 l.min-1, corresponding to 99.7 +/- 20.4% of the predicted maximal oxygen consumption. Physical fitness of lignite miners was comparable with reference values for healthy men in Czech population. The level of physical fitness did not correlate with the length of exposure to underground work.

Allelism tests of 15 dominant cataract mutations in mice.

Fifteen autosomal dominant mutations that cause cataract of lenses in mice were tested for allelism. The outcrosses of double mutants revealed three allelism groups, consisting of 5, 4 and 2 mutations as well as 4 mutations which segregated independently. The results indicated 7 different cataract loci in the sample of 15 mutations. The biomicroscopic examination of the eyes showed that phenotypically similar as well as very distinct cataract mutations can be alleles of the same gene. Conversely, phenotypically similar mutations were shown to be non-allelic.

Characterization of Scat (suture cataract), a dominant cataract mutation in mice.

The autosomal, dominant mutation Scat (suture-cataract) was found in (101/El x C3H/El)F1-hybrid mice. The severity of the cataract is dependent on the gene dose. The mutation causes an anterior suture opacity in heterozygotes amd microphthalmia with vacuolated lenses in homozygotes. In histological sections of lenses the heterozygotes exhibit a hydropic swelling of lens epithelium, whereas in homozygotes interruption and degeneration of lens fibers as well as clefts and folds of the capsule were observed. The mutation has a complete penetrance and constant expressivity. The body weight of the mutants is not altered; the mutation has no effects on fertility or viability. The lens wet and dry weights are diminished (more pronounced in the homozygotes). The water content of the lens is enhanced only in the homozygous Scat mutants. Biochemically, the lenticular content of water-soluble proteins is decreased in the homozygous Scat mutants. By electrophoresis, in the lenses of homozygous Scat mutants a different pattern of water-soluble proteins could be observed. The lenses of both, heterozygous and homozygous Scat mutants exhibit enhanced Na+,K+-ATPase activity and a decreased ATP concentration. The genetical, morphological or biochemical data suggest that the effect of the Scat mutation is distinct from other described cataract mutations in mice.

Towards an understanding of the nature and fitness of induced mutations in germ cells of mice: homozygous viability and heterozygous fitness effects of induced specific-locus, dominant cataract and enzyme-activity mutations.

A total of 219 specific-locus, 35 dominant cataract and 44 enzyme-activity mutations induced in spermatogonia of mice by radiation or ethylnitrosourea (ENU) treatment were characterized for homozygous viability as well as fitness effects on heterozygous carriers. For all 3 genetic endpoints, the frequency of homozygous lethal mutations was higher in the group of radiation-induced mutations than in the ENU-treatment group. These observations are consistent with the hypothesis that radiation-induced mutations recovered in the mouse are mainly due to small deletions while ENU induces mainly intragenic mutations. The overall fitness of mutant heterozygotes was reduced for the group of radiation-induced specific-locus, dominant cataract and enzyme-activity mutations while the ENU-induced mutations exhibited no reduction in fitness. The fitness reduction of heterozygous carriers for a newly occurring mutation in a population is important in determining the persistence of the mutation in a population, and thus the total number of individuals affected before a mutation is eventually eliminated from the population. For the present results a maximal persistence of 12 generations and a minimal persistence of 3 generations is estimated. These results are consistent with the 6-7-generation persistence time assumed by UNSCEAR (1982) in an estimate of the overall effects of radiation-induced mutations in man.

Mutagenicity testing of vincristine sulfate in germ cells of male mice.

Vincristine sulfate (VCR) affects the fertilization ability of all germ-cell stages in male mice. The reduced fertilization ability leads to a pseudo-dominant-lethal effect and sterile matings. The frequency of these effects is dose-dependent. The frequency of specific-locus mutations was not increased by VCR in male mice following 2 mg/kg bw treatment.

Dominant cataract and recessive specific-locus mutations detected in offspring of procarbazine-treated male mice.

The induction of dominant cataract mutations by procarbazine was studied concomitantly with the induction of specific-locus mutations in treated male mice. The most effective dose in the specific-locus test, 600 mg/kg of procarbazine, and a fractionated dose of 5 X 200 mg/kg were used. The frequencies of dominant cataract mutations were higher, but not significantly different from the historical control. The ratio between the number of recovered specific-locus and dominant cataract mutations was in accordance with that found in our experiments with gamma-rays (Ehling et al., 1982; Kratochvilova, 1981) or in experiments with ethylnitrosourea (Favor, 1986). A total of 3 dominant cataract mutations were recovered in the offspring of procarbazine-treated spermatogonial stem cells. Two mutations had complete penetrance while the third exhibited a reduced penetrance of approximately 70%. The viability and fertility of the heterozygotes of all 3 mutations were not affected. Only 1 mutation was shown to be viable as a homozygote.

Induction of gene mutations in mice: the multiple endpoint approach.

The multiple endpoint mammalian mutagenesis approach developed in our institute screens in the same animal for recessive specific-locus alleles at 7 loci, approximately 30 loci coding for dominant-cataract mutations, 23 loci controlling protein-charge changes and 12 loci for enzyme-activity alterations. Experiments to screen for the approximately 70 loci in the same offspring of treated male mice were performed with ethylnitrosourea (ENU), procarbazine and X-ray exposure. Mutations were recovered for each genetic endpoint in all treatment groups where a sufficient number of offspring was scored. ENU treatment is highly effective in inducing mutations to all genetic endpoints. The mutations were confirmed by breeding tests. The mutation rates to specific-locus and enzyme-activity alleles were both higher than the mutation rates to either dominant-cataract or protein-charge alleles. The advantages and possibilities of the multiple endpoint approach are discussed in detail.

Genetical and biochemical studies of a dominant cataract mutant in mice.

A spontaneous mutation causing a nuclear opacity of the lens of the eye was detected among (101 X C3H) F1 hybrid mice. The nuclear opacity, provisional gene symbol Nop, is inherited as a single autosomal dominant gene. Penetrance on the genetic background of the 101-strain is complete. Heterozygotes and homozygotes are viable and fertile. The amount of protein after centrifugation at 3000 g is reduced in the cataractous lens. After isoelectric focusing a band at pH 8.5 in the protein pattern is missing. The glutathione redox-state of the cataractous lens is also affected. The amount of oxidized glutathione relative to the total amount of glutathione is increased from 2.7 to 7.8% in the Nop/ + mutant (P less than 0.01). Enzyme activities connected with the glutathione redox-cycle (glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase) are not affected. The activities of some glycolytic enzymes, phosphoglycerate kinase, glyceraldehyde-phosphate dehydrogenase, phosphoglyceromutase and triosephosphate isomerase are reduced (P less than 0.05). However, the concentration of ATP in the cataractous lens is unchanged.

Dominant cataract mutations and specific-locus mutations in mice induced by radiation or ethylnitrosourea.

In a combined experiment, dominant cataract mutations and specific-locus mutations were scored in the same offspring. In radiation experiments, a total of 15 dominant cataract and 38 specific-locus mutations was scored in 29396 offspring. In experiments with ethylnitrosourea (ENU), a total of 12 dominant cataracts and 54 specific-locus mutations was observed in 12712 offspring. The control frequency for dominant cataracts was 0 in 9954 offspring and for specific-locus mutations 11 in 169955 offspring. The ratio of radiation-induced recessive visible to dominant mutations was about 2.5:1. The difference was even more pronounced for ENU-induced mutations. The ratio of recessive visibles to dominant cataracts for chemically induced mutations in spermatogonia was about 5.4:1. The two characteristic features of radiation-induced specific-locus mutations--the augmenting effect of dose fractionation and the quantitative differences in the mutation rates between spermatogonial and post-spermatogonial stages--can also be demonstrated for the induction of dominant cataracts. The dominant cataract mutations recovered can be categorized into 7 phenotypic classes: total opacity, nuclear and zonular cataract, nuclear cataract, anterior pyramidal cataract, anterior polar cataract, anterior capsular cataract, and vacuolated lens. The largest class of mutations, a total of 11, affected the anterior polar region, while the number of total opacities in both experiments was 5. The only noteworthy difference observed between the radiation- and ENU-induced mutations recovered was that, of the 2 radiation-induced total lens opacities, both were associated with an iris anomaly and microphthalmia whereas the ENU-induced total opacities were not.

Dominant cataract mutations detected in offspring of gamma-irradiated male mice.

The technique of biomicroscopic eye examination followed by breeding tests provides a new method for detection of dominant mutations in mice. A total of 11 cataract mutations were found among 17,436 offspring of irradiated male mice. No cataract mutations were observed in 8,174 offspring from the control group. All mutations were phenotypically different. Of the 11 cataract mutations, 3 were semilethal in heterozygous condition, 7 were lethal in homozygous condition, and one presumed mutant was sterile. Seven mutations had complete penetrance whereas penetrance of three mutations was reduced. The rate of dominant mutations affecting an organ system in mice is of main importance for the quantification of the overall genetic damage due to dominant mutations in man.