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PubMed1983

Comparison of single- and multiple-trait selected sires--response of heifer growth.

Body weights and linear body measurements were on 386 heifers whose sires were selected according to two criteria: 1) Yield, selection only on milk yield Predicted Difference from daughters' first lactations; 2) Merit, selection on a combination of milk yield Predicted Difference (all daughters), udder type, and percentage of daughters leaving herd in first lactation. No significant differences existed between Yield and Merit heifers for body weights at various ages through first calving or in heart girth or withers height through 18 mo of age. Heifers born to dams first parity were lighter at birth but were not significantly different from other parties of dam for weight, withers height, or heart girth at later ages. Differential selection for milk yield as in this study did not change body weight of heifers.

Aging↗

PubMed2006

Natural selection is not required to explain universal compositional patterns in rRNA secondary structure categories.

We have encountered an unexpected property of rRNA secondary structures that may generalize to all RNAs. Analysis of 8892 ribosomal RNA sequences and structures from a wide range of species revealed unexpected universal compositional trends. First, different categories of rRNA secondary structure (stems, loops, bulges, and junctions) have distinct, characteristic base compositions. Second, the observed patterns of variation are similar among sequences from large and small rRNA subunits and all domains of life, despite extensive evolutionary divergence. Surprisingly, these differences do not seem to be related to selection for different compositions in different structural categories, but rather relate to the overall composition of the molecule: Randomized RNAs with no evolutionary history show the same structure-dependent compositional biases as rRNAs. These compositional trends may improve the accuracy of RNA secondary structure prediction, because they allow us to compare predicted structures against known compositional preferences. They also suggest caution in interpreting differences in the rate of change of the GC content in different parts of the molecule as evidence of differential selection.

Base Composition↗

PubMed1982

Morphine withdrawal in mice selectively bred for differential sensitivity to ethanol.

Mice which have been selectively bred for differences in sensitivity to acute doses of alcohol have also been shown to differ in severity of seizures upon withdrawal from chronic alcohol administration. We investigated the responsiveness of these mice to withdrawal from chronic morphine treatment. Mice were made dependent on morphine via pellet implantation, and withdrawal was precipitated with naloxone challenge. Mice which are less sensitive to the hypnotic effects of ethanol (short sleep: SS) displayed more jumping and wet dog shakes during withdrawal than did the more sensitive long sleep (LS) mice. In addition, the amount of jumping was dependent on the dose of naloxone in both lines. Differences between lines in naloxone precipitated withdrawal may reflect differences in alterations in extrapyramidal dopaminergic activity, but other substrates for the observed differences cannot be discounted. Finally, the observed difference between SS and LS mice in severity of morphine withdrawal parallels the previously reported difference between these lines in seizure severity during withdrawal from alcohol.

Alcoholism↗

PubMed1995

[Vaccination immunology].

Vaccines induce the activation and differentiation of antigen specific-T and B lymphocytes, and the development of humoral and cellular effector mechanisms responsible for the destruction of pathogenic agents. The characteristics of the immune response depend on the nature of the antigen, the route of administration of the vaccine and the genotype of the vaccinated individual. Antigen recognition and B and T lymphocyte interactions take place in secondary lymphoid organs. Antigen-stimulated lymph nodes exhibit dramatic changes involving the lymphoid follicles where major events such as clonal selection, differentiation and maturation of B- and T-cell precursors occur. These events include various cellular and lymphokine signals termed cellular cooperation. Different effector mechanisms participate in antigen elimination.

Antigens↗

PubMed1993

Correlated responses in reproductive and carcass traits to selection for 200-day weight in Landrace pigs.

Correlated responses in reproductive and carcass traits from a line of Landrace pigs selected for increased 200-d weight along with a randomly selected control line were studied in 195 litters (109 select, 86 control) and 285 pigs (132 select, 153 control). Reproductive and maternal traits studied included litter sizes born, born alive, and alive at 21 d and litter weights at birth and at 21 d. Carcass traits studied were carcass length, longissimus area, average backfat thickness, 10th-rib backfat thickness, specific gravity, weights of closely trimmed ham, loin, and shoulder, belly weight, subjective scoring of the longissimus muscle for color and marbling, estimated percentage of muscle, and lean growth. Total weighted cumulative selection differential for 200-d weight over six generations was 88.7 kg. The realized heritability for 200-d weight was .26 +/- .08, and the change in 200-d weight was 4.2 +/- 1.3 kg per generation. None of the regression coefficients for reproductive traits differed significantly from zero. Ham weight, belly weight, marbling score, and lean growth increased by .069 +/- .027 kg, .051 +/- .020 kg, .045 +/- .012 points, and .0042 +/- .0007 kg/d, respectively, per generation. Specific gravity decreased by -.00063 +/- .00023 per generation in response to the selection for 200-d weight. The increase in lean growth in the select line was the result of an increased growth rate and not from an improvement in percentage of lean in carcasses from pigs from the select line.

Adipose Tissue↗

PubMed1998

Genetics of immunological tolerance: I. Bidirectional selective breeding of mice for oral tolerance.

The polygenic nature of oral tolerance regulation was elucidated by the method of bidirectional selective breeding of mouse strains for tolerance susceptibility (TS) and resistance (TR) starting from a genetically heterogeneous population achieved by the equilibrated intercrossing of eight inbred mouse strains (A/J, DBA/2J, P/J, SWR/J, SJL/J, CBA/J, BALB/cJ and C57BL/6J). Seven days after intragastric administration of 5 mg OVA or BSA, mice were intraperitoneally immunized with 100 microg of the corresponding antigen. The individual antibody titres were measured by haemagglutination. The phenotypes at the highest and lowest extremes were selected for assortative mating, avoiding consanguinity. The second litter of each mating couple was intraperitoneally immunized only to evaluate the immunocompetence of the corresponding generation and to ascertain the non-selection of non-responder mice. A normal distribution of agglutinin titres ranging from 4 to 14 log2 was observed in the F0 population. In the F12 generation, TR and TS strains showed highly significant differences for agglutinin titres (TR=15.06+/-1.80 and TS=8.35+/-2.44), and IgG responses by ELISA. Up to the F12 generation, the mean realized heritability was 0.14+/-0.02. The response to the selection was 0.43 log2 and the selection differential 3.10 log2/generation. A provisional estimation indicated that oral tolerance may be influenced by eight or nine independent loci.

Administration, Oral↗

PubMed1990

Mass selection for increased 70-day weight in a closed line of Landrace pigs.

Mass selection for increased weight at 70 d of age was practiced for six generations in a line of Landrace pigs. It was desired to have the next generation sired by the heaviest nine boars and out of the heaviest 27 gilts. A contemporaneous, randomly selected (by pedigree) control line was maintained in which the next generation was sired by five boars and out of 10 gilts. Inbreeding coefficients were .208 and .214 for the selected and control line litters and .177 and .189 for the selected and control line dams in the sixth generation, respectively. A total of 1,906 pigs was farrowed with 70-d weights collected on 1,267 pigs. These pigs were sired by 88 boars and out of 190 gilts. The generation interval was 13 mo. Six traits were studied: birth, 21-d, 35-d and 70-d weights and preweaning (from birth to 35 d) and postweaning (from 35 to 70 d) daily gains. Direct and correlated responses per generation and per weighted cumulative selection differential (WCSD) were estimated. Total WCSD for 70-d weight was 30.3 kg. This corresponds to a standardized WCSD of 6.11 phenotypic standard deviations. The response per generation for 70-d weight was .65 +/- .29 kg. The realized heritability for 70-d weight was .13 +/- .06. Nearly all the increased weight at 70 d was the result of more rapid growth in the postweaning period, with little difference in growth in the preweaning period; birth, 21-d and 35-d weights and preweaning daily gains remained unchanged by selection for 70-d weight.

Animals↗

PubMed2003

Genetic evaluation of an index of birth weight and yearling weight to improve efficiency of beef production.

The CGC population is a stabilized composite of 1/2 Red Angus, 1/4 Charolais, and 1/4 Tarentaise germplasm. The objectives of this research were to estimate genetic parameters for weight traits of CGC and to evaluate genetic responses resulting from selection based on the following index: I = 365-d weight 3.2(birth weight). Phenotypes evaluated were birth weight (n = 5,083), 200-d weight (n = 4,902), 365-d weight (n = 4,626), and the index. In addition, there were 1,433 cows with at least one recorded weight, and 4,375 total observations of cow weight collected at the time their calves were weaned. In 1989, a randomly selected control line and a line selected for greater values of the index were established. Average generation intervals were 3.16 +/- 0.04 and 3.90 +/- 0.08 yr in the index and control lines, respectively. The index selection line (n = 950) accumulated approximately 212 kg more selection differential than the control line over three generations (n = 912). Heritability estimates for direct effects were 0.32 +/- 0.04, 0.49 +/- 0.05, 0.49 +/- 0.05, 0.30 +/- 0.04, and 0.70 +/- 0.04 for the index, birth weight, 365-d weight, 200-d weight, and cow weight, respectively. Heritability estimates for maternal effects were 0.05 +/- 0.02, 0.11 +/- 0.03, 0.04 +/- 0.02, and 0.19 +/- 0.04 for the index, birth weight, 365-d weight, and 200-d weight, respectively. In the control line, direct genetic changes for the index and its components were small. For the index selection line, direct genetic changes for the index, birth weight, 365-d weight, 200-d weight, and cow weight were 6.0 +/- 0.3, 0.45 +/- 0.09, 7.74 +/- 0.55, 3.42 +/- 0.25, and 6.3 +/- 0.9 kg/generation, respectively. Maternal genetic changes were generally small for both the control and index selection lines. Thus, selection for the index produced positive correlated responses for direct genetic effects on BW traits at all ages, with only minor effects on maternal genetic effects. Results demonstrate that despite a genetic antagonism that compromises selection response for decreased birth weight and increased postnatal growth, favorable genetic responses can be achieved with the selection index used in this study.

Animals↗

PubMed2025

Biomarker-Based Nomogram to Predict Neoadjuvant Chemotherapy Response in Muscle-Invasive Bladder Cancer.

Background/Objectives: The aim of this study was to identify response prediction and prognostic biomarkers in muscle-invasive bladder cancer (MIBC) patients undergoing neoadjuvant chemotherapy (NAC). Methods: A retrospective multicentre study including 191 patients with MIBC who received NAC previous to radical cystectomy (RC) between 1996 and 2013. Gene expression patterns were analysed in 34 samples from transurethral resection of the bladder (TURB) using Illumina microarrays. The expression levels of 45 selected differentially expressed genes between responders and non-responders to NAC were validated by quantitative PCR in an independent cohort of 157 patients. Regression analysis was used to identify predictors of downstaging and relapse. A nomogram for predicting downstaging and relapse-including clinicopathological and gene expression variables-was developed. Results: The expression levels of 1352 transcripts differed between responders and non-responders to NAC. A nomogram based on the most predictive clinical variables (age, Tis (in situ), gender, history of NMIBC, and lymphadenopathy) and genes selected following the Akaike information criterion (AIC) (CBTB16, CHMP6, DDX54, CASP8, LOR, and PLEC) was then created. In addition, a three-gene expression prognostic model to predict tumour relapse was generated. This model was able to discriminate between two groups of patients with a significantly different probability of tumour relapse (HR: 2.11; CI: 1.16-3.83, p = 0.01). Conclusions: Our nomogram based on gene expression and clinical data is a useful tool to predict downstaging and tumour relapse after NAC in MIBC patients. Further validation is warranted.

bladder cancer↗

PubMed1981

Functional opiate receptors in the guinea-pig ileum: their differentiation by means of selective tolerance development.

A differentiation of multiple opiate receptors in the electrically stimulated longitudinal muscle-myenteric plexus preparation of the guinea-pig ileum is described employing the technique of tolerance development of selective opiate receptors. Apparently, mu- and kappa-opiate receptors are clearly differentiated in this tissue, since highly tolerant mu-receptors (80-fold) coexist with kappa-receptors of almost normal sensitivity and vice versa. Attempts to demonstrate delta-receptors failed, as there was complete cross-tolerance between mu- and delta-agonists. It is proposed that delta-agonists bring about their action via mu-receptors in this preparation. Although mu- and kappa-receptors have been demonstrated, neither of them appear to represent a uniform population.

Animals↗

PubMed1983

Use of repeated matings to estimate environmental and genetic trends and effects of relaxing selection in a selected strain of Leghorn chickens.

Response from index selection for egg production traits in a Leghorn strain over 7 years was partitioned into estimates of total (delta T), temporary (delta R), and net genetic (delta G) response, by producing progeny from selected (A) and unselected (D) first year breeders and from second year breeders (B) and first year full-sisters of previous years A breeders (C). In A, B, C, and D populations, average yearly number of full-sib families was 121, 47, 37, and about 50 and of birds with complete records was 824, 287, 258, and 298. Restricting A to repeated B families added positive bias in delta G for viability, age at first egg, and rate of lay. Estimates of delta G and delta R from B and C populations were similar. Yearly environmental change (delta E) was over three times the phenotypic change (delta P) for egg numbers, emphasizing necessity for intra-year estimates of delta G and delta R. Temporary response (delta R) approached or exceeded total response (delta T) for mortality and accounted for 40% of delta T for rate of lay and 60% for economic index, suggesting adverse maternal environmental effects from relaxing selection (D). Net yearly genetic change (delta G) was 1.5% for rate of lay, $.18 per bird, and in desired direction for most traits. Estimated net yearly response for rate of lay exceeded that predicted from .64 sigma male and .92 sigma female index selection differentials and sire-component genetic parameters (.6%) but agreed ($.16) for economic index. Efficiency and bias for the repeat-mating design are handicapped by mortality and health-related maternal effects.

Animals↗

PubMed1998

Selection bias in occupational sperm studies.

Participation rates in sperm studies are typically 25-50%, and therefore it is a matter of concern whether the men who provide semen samples truly reflect the parent population. The authors analyzed data from three Danish occupational sperm studies and evaluated the relation between age and occurrence of subfertility to participation and provision of semen samples. Age and subfertility were found to be rather strong determinants of participation. Willingness to provide semen samples was greater among men aged <40 years (odds ratio (OR) = 1.8, 95% confidence interval (CI) 1.3-2.6) and among men who had experienced an infertile period (OR = 1.7, 95% CI 1.3-2.1). Furthermore, the effect of infertility was modified by occupational exposure status, thus resulting in a tendency to differential selection and possibly biased risk estimates. In a cross-sectional study, the authors recommend that priority be given to a high participation rate and that data on the basic variables be collected from the entire study population, so that it is possible to make a nonresponder analysis and evaluate bias. Such an analysis can be carried out by means of questions enquiring about infertility, genital disorders, and earlier seminal examinations. Although the longitudinal study design is without many of the limitations of the cross-sectional study, a longitudinal study is usually not feasible.

Adolescent↗

PubMed1993

Heredity of muscle fibre composition estimated from a selection experiment in rats.

The extent to which muscle fibre composition was determined by the genes transmitted from parents was estimated by using successive selections of rats. A foundation population (G0) was established to carry out the selections; it consisted of 100 albino rats which were randomly chosen from heterogeneous stock. The heterogeneous stock was produced by random-mating of three strains, Wistar-Imamichi, Fischer 344 and Donryu. Successive selection for a high percentage of slow twitch fibres (% ST) was made from G0 to the fourth generation (G4). The mean values of % ST changed from 50.0% in G0 to 55.6% in G4. The mean value in G4 was significantly higher than that in G0. The realized heritability in G0-G4 was calculated from the regression of selection response on the cumulated selection differential. The regression coefficient was 0.17 (SEM 0.04). The realized heritability was significantly different from 0 at the 0.05 level. We concluded that in rats about 17% of the variation of muscle fibre composition was determined by the genes transmitted from parents.

Animals↗

PubMed2003

Ring-expanded ("fat") nucleoside and nucleotide analogues exhibit potent in vitro activity against flaviviridae NTPases/helicases, including those of the West Nile virus, hepatitis C virus, and Japanese encephalitis virus.

A series of ring-expanded ("fat") heterocycles, nucleoside and nucleotide analogues (RENs) containing the imidazo[4,5-e][1,3]diazepine ring system (9, 14, 15, 18, 24-26, 28, 31, and 33) and imidazo[4,5-e][1,2,4]triazepine ring systems (30b, 30c, 32, and 34), have been synthesized as potential inhibitors of NTPases/helicases of Flaviviridae, including the West Nile virus (WNV), hepatitis C virus (HCV), and Japanese encephalitis virus (JEV). An amino-terminal truncated form of human enzyme Suv3(delta1-159) was also included in the study so as to assess the selectivity of RENs against the viral enzymes. The analogues of RENs included structural variations at position 1 of the heterocyclic base and contained changes in both the type of sugar moieties (ribo, 2'-deoxyribo, and acyclic sugars) and the mode of attachment (alpha versus beta anomeric configuration) of those sugars to the heterocyclic base. The target RENs were biochemically screened separately against the helicase and ATPase activities of the viral NTPases/helicases. A number of RENs inhibited the viral helicase activity with IC50 values that ranged in micromolar concentrations and exhibited differential selectivity between the viral enzymes. In view of the observed tight complex between some nucleosides and RNA and/or DNA substrates of a helicase, the mechanism of action of RENs might involve their interaction with the appropriate substrate through binding to the major or minor groove of the double helix. The REN-5'-triphosphates, on the other hand, did not influence the above unwinding reaction, but instead exerted the inhibitory effect on the ATPase activity of the enzymes. The activity was found to be highly dependent upon the low concentration levels of the substrate ATP. At concentrations >500 microM of RENs and the ATP concentrations >10 times the Km value of the enzyme, a significant activation of NTPase activity was observed. This activating effect underwent further dramatic enhancement (>1000%) by further increases in ATP concentration in the reaction mixture. A tentative mechanistic model has been proposed to explain the observed results, which includes an additional allosteric binding site on the viral NTPases/helicases that can be occupied by nucleoside/nucleotide-type molecules such as RENs.

Adenosine Triphosphatases↗

PubMed1985

Targeted selection experiments and enzyme polymorphism: negative evidence for octanoate selection at the G6PD locus in Drosophila melanogaster.

Published studies have reported significant selection with respect to the G6pd locus for Drosophila melanogaster reared on Na-octanoate food. We have reexamined the selective effects of Na-octanoate on egg to adult viability with respect to the G6pd polymorphism using specially constructed X chromosomes. Four experiments were carried out using different 6Pgd backgrounds in two recombinant sets of chromosomes segregating for the G6pd locus but constructed so as to minimize variation over most of the X chromosome. In addition, two measures of viability were used, and the size of the experiments and their associated degrees of freedom are approximately double those reported in the former studies. Our results find no evidence for differential selection on G6pd genotypes (males and females) by Na-octanoate and, therefore, do not corroborate the positive results of selection reported by other investigators. The reasons for our different results are discussed.

Animals↗

PubMed2004

[2-DE profiling and differential analysis of human bronchial epithelial tissues in different stages of carcinogenesis].

BACKGROUND & OBJECTIVE: The carcinogenesis of bronchial epithelial cells is a complex multiple-stage process involving multiple genes, but its mechanism remains unclear. Studying this process with proteomic approaches may identify carcinogenesis-associated proteins, which are important for elucidating carcinogenic mechanism of human lung squamous carcinoma. This study was designed to optimize the protein preparation methods for bronchial epithelial tissues, to establish two-dimensional gel electrophoresis profiles of human bronchial epithelial tissues from different stages in carcinogenic process, and to perform differential analysis and provide a basis for identifying carcinogenesis-associated proteins of lung squamous carcinoma. METHODS: After obtaining samples of the normal, metaplasia, dysplasia, carcinoma tissues of human bronchial epithelia, modified deoxycholate- trichloroaetic acid (DOC-TCA) precipitation was used to extract and purify the total proteins of bronchial epithelial samples. Immobilized pH gradient two-dimensional polyacrylamide gel electrophoresis (2-DE) was used to separate the total proteins of the samples. After silver staining, ImageMaster 2-DE image analysis software was applied to analyze 2-DE images. Some selected differential protein spots were identified by peptide mass fingerprint (PMF) based on matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and database search. RESULTS: The total proteins extracted with the method described here were used to perform 2-DE. 2-DE patterns with high resolution and reproducibility from different stages were obtained. The average spots for normal epithelium, metaplasia, dysplasia and invasive carcinoma were 1189.50+/-39.89, 1227.00+/-37.90, 1273.00+/-43.31, and 1326.00+/-66.63, respectively. The test was repeated, which showed that there were average 1216 +/- 75 spots among 3 gels of the same metaplasia tissues and 1082 +/- 67 spots were matched. The average matching rate was 89.3% and protein spots in 3 gels had good reproducibility. The average position deviation of matched spots in different gels was 0.865+/- 0.247 mm in IEF direction, and 0.971+/- 0.104 mm in SDS-PAGE direction. The 2D images of 32 samples were compared, which showed a significant difference of the number of average protein spots among the four groups (P< 0.05). The average differential spots between the low and advanced stages were 31.50 +/- 7.67, 41.00 +/- 9.07, and 56.00 +/- 8.96, respectively. Twenty-three protein spots chosen randomly from dysplasia and invasive carcinoma groups were identified by PMF, some of which were involved in the cell proliferation, differentiation, cycle regulation, signal transduction and tumor occurrence. CONCLUSIONS: (1) Improved DOC-TCA precipitation is a preferable method for protein preparation from bronchial epithelial tissues. (2) We established well-resolved, reproducible 2-DE profiles of human bronchial epithelial tissue in different stages of carcinogenesis. Some differentially expressed-proteins may be related to carcinogenesis of bronchial epithelia. These results provide a fundamental basis for further study of carcinogenic mechanism of lung squamous cancer and screening its specific marker.

Bronchi↗

PubMed2005

Genetic evaluation of the ratio of calf weaning weight to cow weight.

The phenotypic ratio of a calf's weaning weight to its dam's weight is thought to be an indicator of efficiency of the cow. Thus, the objectives of this research were to 1) estimate genetic parameters for the ratio of 200-d calf weight to mature-equivalent cow weight at weaning, its components, and other growth traits; and 2) evaluate responses to selection based on the ratio. Phenotypes evaluated were the ratio (100 kg/ kg; n = 4,184), birth weight (kg; n = 5,083), 200-d weight (kg; n = 4,902), 365-d weight (kg; n = 4,626), and mature-equivalent cow weight at weaning (kg; n = 4,375). In 1989, a randomly selected and mated control line and a line selected for greater values of the ratio were established. Average generation intervals were 3.39 +/- 0.05 and 3.90 +/- 0.08 yr in the ratio selected line and control line, respectively. The ratio selection line (n = 895) accumulated approximately 4.7 SD more selection differential than the control line (n = 912) over 2.5 generations. Data were analyzed with a multiple-trait Gibbs sampler for animal models to make Bayesian inferences. Heritability estimates (posterior mean +/- SD) for direct effects were 0.20 +/- 0.03, 0.46 +/- 0.04, 0.48 +/- 0.03, 0.58 +/- 0.04, and 0.76 +/- 0.02 for ratio, birth weight, 200-d weight, 365-d weight, and cow weight, respectively. Estimates for heritability of maternal effects were 0.58 +/- 0.05, 0.10 +/- 0.02, 0.13 +/- 0.02, and 0.10 +/- 0.02 for ratio, birth weight, 200-d weight, 365-d weight, respectively. Significant response to selection was limited to maternal effects: 1.32 +/- 0.38 ratio units per generation. As the ratio was a trait of the calf, estimated maternal genetic effects on the ratio contained both genetic effects due to dams that environmentally affected progeny performance and direct effects on the reciprocal of cow weight. In the control line, genetic trends in direct and maternal 200-d weight were -1.28 +/- 0.91 and 0.62 +/- 0.92 kg/generation, respectively, and the genetic trend in direct effects on cow weight was -5.72 +/- 2.80 kg/ generation. In the selection line, genetic trends in direct and maternal 200-d weight were 1.43 +/- 0.79 and 2.90 +/- 0.80 kg/generation and the genetic trend in cow weight was -2.79 +/- 2.43 kg/generation. Significant correlated responses were observed in direct effects on birth weight and maternal effects on 365-d weight. Results contraindicate use of the ratio of calf weaning weight to cow weight as a selection criterion.

Animal Husbandry↗

PubMed2003

[Out-of-laboratory control screening of growth mediums used by sanitary service laboratories for isolation of pathogenic enteric bacteria from fecal specimens].

The aim of the study was to test the selective-differential plating mediums used for isolation of Salmonella and Shigella for routine stool specimens examination for epidemiological and sanitary purpose. Three plates of any such medium used in the laboratories in 37 Sanitary Service Stations in Poland were obtained. The specimens of Mac Conkey Lactose Bile Salt Agar and SS Agar were obtained from all laboratories, Hektoen Enteric medium from 8 and EosinMethylene Blue Agar from only one laboratory. The desiccated substrates of these mediums originated from 11 manufactures. The mediums were inoculated by "drops" method. The five control strains of selected taxons were chosen from National Institute of Hygiene strains collection. The quality of growth was evaluated by comparison with the growth on two control mediums: the general outlook of bacterial colonies, size and number of cfu/ml was taken under consideration. It was found that the results were satisfying for Hektoen medium, Levine and all but two Mac Conkey's medium specimens. The results of growth on SS medium were much worse: only on 10 specimens out of 39 checked supported properly the growth of all the five control strains. On 18 specimens the growth appeared after 48 hours of incubation and the size of colonies was too small to be isolated. On 11 there was no growth on 1, 2 or 3 control strains. The need of systematic extra-laboratory control of plating mediums used for examination stool specimen was shown.

Bacteriological Techniques↗