Assessment of permissible levels of radionuclides in soil for different types of land-use.

Permissible levels of radionuclides in soil were estimated for different human dose criteria. A variety of land-use scenarios, which could lead to human exposure, was considered and all reasonably likely human exposure pathways were analyzed. The obtained estimates are potentially useful for supporting the decision-making process on the possible use or remediation of contaminated territories.

[X-ray manifestations of maxillary cavitary masses].

The paper deals with the X-ray manifestations of different maxillary pathological processes accompanied by the cavitary symptom. Analysis of X-ray films of different types in 250 patients has indicated that the nature of cavitary mass can be determined in many cases.

Mathematical simulation of dose-effect relationships for fish eggs exposed chronically to ionizing radiation.

A mathematical model which simulates the observed dose-effect relationships for fish eggs exposed to chronic irradiation is presented. The model assumes that the exposed fish eggs may exist in one of the following states: normally developing, reversibly damaged, and lethally damaged. Reversible damages may be recovered by repairing mechanisms which are spent for the repairing processes. The model was applied to describe the observed differences in effects of chronic exposure for quickly (2 weeks) and slowly (up to 20 weeks) developing fish eggs. Calculations were performed for dose rates of chronic irradiation ranging from 10 to 300 mGy/day. Two types of radiation effects were considered-the effect on eggs survival (percentage of survived eggs at time t), and the depletion of the repairing pool (in percentage of its maximal value). The model predictions have been compared with the experimental data from the EPIC database. This comparison showed that the model adequately describes the radiation effects in fish eggs of different species, within a wide range of chronic radiation exposures.

[Distribution of lysotypes and study of antibiotic sensitivity of Shigella flexneri 2 isolated in Iran]. / Répartition des lysotypes et étude de la sensibilité aux antibiotiques des Shigella flexneri 2 isolées en Iran

152 strains of Shigella flexneri 2 isolated from the stools of patients having sporadic bacillary dysenteria have been studied for their phage types as well as for the presence of transferable resistance factor. The distribution of the phage types has shown a high predominance of lysotype 12 (67%). Proportion of Shigella flexneri 2 strains resistant to one or several antibiotics has been highest in the years 1968 and 1973. The most frequent transferable resistance pattern was found to be (Tc, Cm, Sm, Su) and the most successful transfer method was the celophane technique. Resistance loss varied according to the resistance pattern of the strains. Total loss of the resistance to Tc, Cm, Sm, Su occurred in 0,2-2 % only. Very often strains resistant to Tc, Cm, Sm, Su lost their resistance factor to Tc and Cm keeping the resistance factors for Su, Sm.

Relation between Salmonella typhimurium biotypes and drug resistance, Teheran, Iran (1962-1973).

According to the procedure of Cordano (1971), the identification of biotypes of 118 strains of Salmonella typhimurium isolated from stools or rectal swabs of patients with sporadic cases of diarrhoea on the Central Plateau during the period 1962-1973 revealed that: From 118 S. typhimurium, 65 (55-1%) were biotype "d", 50 (42-4%) were "a" and three (2-5%) were "b". The predominant biotype was "d", followed by the "a" biotype, and "b" was rarely encountered. Biotype "d" has existed since 1965, and after that date has increased. Biotype "a" existed from the beginning of the study, but has decreased during the period 1962-1973. Sensitivity tests were performed according to Bauer (1966). Biotypes "d" and "a" showed a high degree of resistance to tetracycline, chloramphenicol, streptomycin, triple-sulfa, ampicillin, furazolidone, kanamycin, neomycin, paromomycin, cephalothin and co-trimoxazole. All isolated biotypes "d" were multiple drug-resistant, while some of the strains of biotype "a" were resistant and some sensitive. All three biotypes "b" were sensitive to all drugs examined. Resistance to drugs for biotypes "d" and "a" increased with time. The predominant pattern of resistance for all biotypes was found to be resistance to eight drugs: tetracycline, chloramphenicol, streptomycin, triple-sulfa, ampicillin, kanamycin, neomycin and paromomycin (Tc, Cm, Sm, Su, Am, K, N, Par). Considering the relationship between resistance pattern and biotypes, the predominant pattern in biotype "d" was resistance to eight drugs (Tc, Cm, Sm, Su, Am, K, N, Par) (47-7%), and in biotype "a" was resistance to nine drugs, tetracycline, chloramphenicol, streptomycin, triple-sulfa, ampicillin, furazolidone, kanamycin, neomycin, paromomycin (Tc, Cm, Sm, Su, Am, Fx, K, N, Par) (28%).

Transfer of drug resistance factor in Shigella sonnei isolated in Iran.

The pattern of drug resistance and incidence of R-factors were studied in Shigella sonnei strains isolated in Iran. Eighty-nine out of 172 strains (51.7%) were resistant to one or more drugs and multiple drug resistance was more common than single drug resistance. The most predominant pattern of resistance observed was (Tc, Cm, Sm, Su). By mixed cultivation, 85.7% of Shigella sonnei resistant strains isolated on the Central Plateau and 100% of the strains from the caspian littoral transferred at least a part of their resistance pattern to sensitive E. coli K12 F- (gamma). In this experiment, 67.1% of our resistant and 17% of our sensitive strains had colicinogenic properties. No such difference could be observed between R+ and sensitive strains isolated in the Caspian littoral.