RESUMO
BACKGROUND: A strong, consistent association between childhood irradiation and subsequent thyroid cancer provides an excellent model for studying radiation carcinogenesis. METHODS: We evaluated gene expression in 63 paired RNA specimens from frozen normal and tumour thyroid tissues with individual iodine-131 (I-131) doses (0.008-8.6 Gy, no unirradiated controls) received from Chernobyl fallout during childhood (Ukrainian-American cohort). Approximately half of these randomly selected samples (32 tumour/normal tissue RNA specimens) were hybridised on 64 whole-genome microarrays (Agilent, 4 × 44 K). Associations between I-131 dose and gene expression were assessed separately in normal and tumour tissues using Kruskal-Wallis and linear trend tests. Of 155 genes significantly associated with I-131 after Bonferroni correction and with ≥2-fold increase per dose category, we selected 95 genes. On the remaining 31 RNA samples these genes were used for validation purposes using qRT-PCR. RESULTS: Expression of eight genes (ABCC3, C1orf9, C6orf62, FGFR1OP2, HEY2, NDOR1, STAT3, and UCP3) in normal tissue and six genes (ANKRD46, CD47, HNRNPH1, NDOR1, SCEL, and SERPINA1) in tumour tissue was significantly associated with I-131. PANTHER/DAVID pathway analyses demonstrated significant over-representation of genes coding for nucleic acid binding in normal and tumour tissues, and for p53, EGF, and FGF signalling pathways in tumour tissue. CONCLUSION: The multistep process of radiation carcinogenesis begins in histologically normal thyroid tissue and may involve dose-dependent gene expression changes.
Assuntos
Acidente Nuclear de Chernobyl , Expressão Gênica/efeitos da radiação , Radioisótopos do Iodo/administração & dosagem , Neoplasias Induzidas por Radiação/etiologia , Neoplasias Induzidas por Radiação/genética , Glândula Tireoide/efeitos da radiação , Neoplasias da Glândula Tireoide/etiologia , Neoplasias da Glândula Tireoide/genética , Adolescente , Adulto , Criança , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Transcriptoma/efeitos da radiação , Adulto JovemRESUMO
Antimony leaching from sulfide ore samples by an experimental consortium of thermoacidophilic microorganisms, including Sulfobacillus, Leptospirillum, and Ferroplasma strains was studied. The ores differed significantly in the content of the major metal sulfides (%): Sb(S), 0.84 to 29.95; Fe(S), 0.47 to 2.5, and As(S), 0.01 to 0.4. Independent on the Sb(S) concentration in the experimental sample, after adaptation to a specific ore and pulp compaction the microorganisms grew actively and leached/oxidized all gold-antimony ores at 39 ± 1 degrees C. The lower was the content of iron and arsenic sulfides, the higher was antimony leaching. For the first time the investigations conducted with the use of X-ray microanalysis research made it possible to conclude that in a natural high-antimony ore Sb inhibits growth of only a part of the cell population and that Ca, Fe, and Sb may compete for the binding centers of the cell.
Assuntos
Antimônio/metabolismo , Bactérias/metabolismo , Ouro/metabolismo , Consórcios Microbianos/fisiologia , Antimônio/química , Bactérias/ultraestrutura , Ouro/química , OxirreduçãoRESUMO
A comparative analysis of the expression of both, RET/PTC1 and RET/PTC3 oncogenes in papillary thyroid carcinomas (PTC) of patients from different age groups was carried out. Those were the following groups: children (mean age - 13 years, mean latency period - 13 years), young adults (mean age - 24 years, mean latency period - 14 years), adults (mean age - 38 years, mean latency period - 22 years). The presence of RET/PTC oncogenes was detected using polymerase chain reaction. In all cases the samples of both tumor and normal thyroid tissue were studied. It was established that induction of both, RET/PTC1 and RET/PTC3 rearrangements was present only in carcinoma samples. In PTCs the percentage of RET/PTC-positive tumors with increasing the age of patients has been decreasing. It should be noted that the part of carcinomas with induction of RET/PTC1 did not change with increasing the age of patients. At the same time the frequency of RET/PTC3 rearrangements with the increasing both the latency period and age of patients, significantly decreased. In conclusion, our data can evidence for the presence of correlation between the age of patients, latency period and induction of RET/PTC3 oncogenes.
Assuntos
Neoplasias/genética , Isoformas de Proteínas/genética , Proteínas Proto-Oncogênicas c-ret/genética , Adolescente , Adulto , Fatores Etários , Carcinoma , Carcinoma Papilar , Causalidade , Acidente Nuclear de Chernobyl , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Neoplasias/epidemiologia , Neoplasias/metabolismo , Neoplasias/patologia , Reação em Cadeia da Polimerase , Isoformas de Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-ret/metabolismo , Câncer Papilífero da Tireoide , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/patologia , Microambiente Tumoral , Ucrânia , Adulto JovemRESUMO
Five cultures of moderately thermophilic spore-forming acidophilic chemolithotrophic bacteria were isolated from the zones of spontaneous heating of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ores in an operating open pit (strains B1, B2, B3, OFO, and SSO). Analysis of the chromosomal DNA structure revealed differences between these cultures at the strain level (apart from B3 and SSO, which had identical restriction profiles). All the strains had a similar G + C DNA molar content (47.4-48.3%). The level of DNA reassociation was 85 to 95%. The similarity between the DNA of the type strain Sulfobacillus sibiricus N1 isolated from arsenopyrite ore concentrate and that of these strains (83-93%) indicates that they belong to the same species. The strains had similar values of pH and temperature optimal for growth on ferrous iron (1.6-2.0 and 45-55 degrees C, respectively). They were mixotrophs; Fe(II), S0, and sulfide minerals along with organic compounds were used as energy sources and electron donors. However, the kinetic parameters of growth and substrate oxidation varied from strain to strain. Genetic variety of the strains from diverse ecosystems and environments is possibly the result of the different rates of microevolution processes.
Assuntos
Bacillus/fisiologia , Bacillus/classificação , Bacillus/isolamento & purificação , Composição de Bases , Biodiversidade , DNA Bacteriano/genética , Compostos Ferrosos/metabolismo , Sedimentos Geológicos/microbiologia , Concentração de Íons de Hidrogênio , Compostos Orgânicos/metabolismo , Oxirredução , Sulfatos/metabolismo , Enxofre/metabolismo , TemperaturaRESUMO
The phenotypic characteristics of the species Sulfobacillus thermotolerans Kr1(T), as dependent on the cultivation conditions, are described in detail. High growth rates (0.22-0.30 h(-1)) and high oxidative activity were recorded under optimum mixotrophic conditions at 40 degrees C on medium with inorganic (Fe(II), S(0), or pyrite-arsenopyrite concentrate) and organic (glucose and/or yeast extract) substrates. In cells grown under optimum conditions on medium with iron, hemes a, b, and, most probably, c were present, indicating the presence of the corresponding cytochromes. Peculiar extended structures in the form of cylindrical cords, never observed previously, were revealed; a mucous matrix, likely of polysaccharide nature, occurred around the cells. In the cells of sulfobacilli grown litho-, organo-, and mixotrophically at 40 degrees C, the enzymes of the three main pathways of carbon utilization and some enzymes of the TCA cycle were revealed. The enzyme activity was maximum under mixotrophic growth conditions. The growth rate in the regions of limiting temperatures (55 degrees C and 12-14 degrees C) decreased two- and tenfold, respectively; no activity of 6-phosphogluconate dehydrogenase, one of the key enzymes of the oxidative pentose phosphate pathway, could be revealed; and a decrease in the activity of almost all enzymes of glucose metabolism and of the TCA cycle was observed. The rate of 14CO2 fixation by cells under auto-, mixo-, and heterotrophic conditions constituted 31.8, 23.3, and 10.3 nmol/(h mg protein), respectively. The activities of RuBP carboxylase (it peaked during lithotrophic growth) and of carboxylases of heterotrophic carbon dioxide fixation were recorded. The physiological and biochemical peculiarities of the thermotolerant sulfobacillus are compared versus moderately thermophilic sulfobacilli.
Assuntos
Bactérias Gram-Positivas Formadoras de Endosporo/fisiologia , Bactérias Gram-Positivas Formadoras de Endosporo/ultraestrutura , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Meios de Cultura , Bactérias Gram-Positivas Formadoras de Endosporo/química , Heme/análise , Oxirredução , Espectrofotometria , TemperaturaRESUMO
The dynamics of the ATP pool in the aerobic spore-forming acidothermophilic mixotrophic bacteria Sulfobacillus thermotolerans Kr1T and Alicyclobacillus tolerans K1T were studied in the course of their chemolithoheterotrophic, chemoorganoheterotrophic, and chemolithoautotrophic growth. It was established that, during mixotrophic growth, the maximum ATP concentrations in the cells of S. thermotolerans Kr1 and A. tolerans K1 were 3.8 and 0.6 nmol/mg protein, respectively. The ATP concentrations in sulfobacilli and alicyclobacilli during organotrophic growth were 2.2 and 3.1 nmol/mg protein, respectively. In the cells of the obligately heterotrophic bacterium Alicyclobacillus cycloheptanicus 4006T, the maximum ATP concentration was several times higher and reached 12.3 nmol/mg protein. During lithotrophic growth, the maximum values of the ATP concentration in the cells of S. thermotolerans Kr1 and A. tolerans K1 were 0.3 and <0.1 nmol/mg protein, respectively; in the cells of the autotrophic bacterium Acidithiobacillus ferrooxidans TFBk, the ATP content was about 60-300 times higher (17.0 nmol/mg protein). It is concluded that low ATP content is among the possible causes of growth cessation of S. thermotolerans Kr1 and A. tolerans K1 under auto- and heterotrophic conditions after several culture transfers.
Assuntos
Trifosfato de Adenosina/metabolismo , Bacilos Gram-Positivos Formadores de Endosporo/metabolismo , Trifosfato de Adenosina/análise , Meios de Cultura , Citoplasma/metabolismo , Bacilos Gram-Positivos Formadores de Endosporo/crescimento & desenvolvimento , Medições LuminescentesRESUMO
We conducted a comparative study of the effects of alpha-amino-gamma-butyrolactone, the common structural element of extracellular microbial regulators of the homoserine lactone (HSL) group, and of 4-n-hexylresorcinol, an autoregulator of the alkylhydroxybenzene (AHB) group, on the growth and development of gram-positive and gram-negative bacteria. We revealed non-species-specific effects of HSL and AHB and characterized their concentration dependencies. The addition of 10(-5)-10(-3) M HSL or 10(-5)-10(-4) M AHB during the exponential growth phase of the cultures grown on balanced media resulted in cell division arrest and accelerated the transition to the stationary phase that culminated in endospore formation in Bacillus cereus, Alicyclobacillus tolerans, and Sulfobacillus thermosulfidooxidans. When bacilli grew under the cultivation conditions that resulted in a low-zero spore percentage, 10(-4)-10(-3) M HSL cancelled the inhibition of spore formation. In the gram-negative bacteria Pseudomonas aurantiaca and Azotobacter vinelandii, AHB at concentrations of 10(-4) to (1.5-2.5) 10(-4) M induced the formation of dormant cells. Studies with the actinobacterium Streptomyces avermitilis revealed that the HSL effect varied depending on the age of the test cultures. The addition of 10(-4) M HSL during the lag phase of a submerged streptomycete culture accelerated its transition to the stationary phase and induced the formation of endospores, the dormant cells that are regarded as alternatives to exospores (conidia). If HSL (3.64 and 4.55 mg per 1cm2 disc) was locally added to a surface S. avermitilis culture, the growing mycelium formed rings that differed in their density, in the extent of the development of aerial mycelium, and in the presence/absence of exospores. Ring-shaped growth of streptomycete mycelia was also induced by 0.075-0.75 mg of AHB; however, unlike HSL, AHB repressed exospore formation. The data on non-species-specific effects of HSL and AHB suggest that they may perform regulatory functions on the microbial community level.
Assuntos
4-Butirolactona/análogos & derivados , Anti-Infecciosos Locais/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Hexilresorcinol/farmacologia , 4-Butirolactona/farmacologia , Divisão Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Bactérias Gram-Negativas/crescimento & desenvolvimento , Bactérias Gram-Positivas/crescimento & desenvolvimento , Especificidade da EspécieRESUMO
CONTEXT: Due to the Chornobyl accident, millions were exposed to radioactive isotopes of iodine and some received appreciable iodine 131 (131I) doses. A subsequent increase in thyroid cancer has been largely attributed to this exposure, but evidence concerning autoimmune thyroiditis (AIT) remains inconclusive. OBJECTIVE: The objective of the study was to quantify risk of AIT after 131I exposure. DESIGN/SETTING/PARTICIPANTS: Baseline data were collected from the first screening cycle (1998-2000) of a large cohort of radiation-exposed individuals (n = 12,240), residents of contaminated, iodine-deficient territories of Ukraine. Study individuals were under the age of 18 yr on April 26, 1986, and had thyroid radioactivity measurements made shortly after the accident. OUTCOMES: AIT was defined a priori based on various combinations of elevated antibodies to thyroid peroxidase (ATPO), TSH, and clinical findings; elevated ATPO were considered to be an indicator of thyroid autoimmunity. RESULTS: No significant association was found between 131I thyroid dose estimates and AIT, but prevalence of elevated ATPO demonstrated a modest, significant association with 131I that was well described by several concave models. This relationship was apparent in individuals with moderately elevated ATPO and euthyroid, thyroid disease-free individuals. CONCLUSIONS: Twelve to 14 yr after the Chornobyl accident, no radiation-related increase in prevalence of AIT was found in a large cohort study, the first in which 131I thyroid doses were estimated using individual radioactivity measurements. However, a dose-response relationship with ATPO prevalence raises the possibility that clinically important changes may occur over time. Thus, further follow-up and analysis of prospective data in this cohort are necessary.
Assuntos
Carcinoma/epidemiologia , Acidente Nuclear de Chernobyl , Radioisótopos do Iodo/efeitos adversos , Neoplasias Induzidas por Radiação/epidemiologia , Doenças da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologia , Tireoidite Autoimune/epidemiologia , Adolescente , Autoanticorpos/sangue , Autoantígenos/imunologia , Criança , Pré-Escolar , Estudos de Coortes , Estudos Transversais , Feminino , Humanos , Lactente , Recém-Nascido , Iodeto Peroxidase/imunologia , Proteínas de Ligação ao Ferro/imunologia , Masculino , Programas de Rastreamento/métodos , Doses de Radiação , Ucrânia/epidemiologiaRESUMO
Our objective is to assess the regional and temporal dependences of the baseline cases contributing to thyroid cancer incidence among those exposed in childhood or during adolescence in Belarus and Ukraine after the Chernobyl accident. Data are analysed for Kyiv and Sevastopol City and the 25 oblasts (regions) in Ukraine, and for Minsk and Gomel City and the 6 oblasts in Belarus. Average thyroid doses due to the Chernobyl accident were assessed for every birth year in the period from 1968 to 1985. Case data pertain to people who underwent surgical removal of thyroid cancers during the period 1986 to 2001 and who were allocated to their place of residence at the time of the accident. The 35 oblasts/cities were subdivided into an upper, middle and lower group of baseline thyroid cancer incidence. Poisson regressions were performed to estimate age, time and gender dependences of the baseline incidence rates in the three groups. The majority of oblasts/cities with high average doses and the majority of Belarusian oblasts/cities belong to the upper group of baseline thyroid cancer incidence. The baseline in the upper group is estimated to be larger than in the middle group by a factor of 2.3, and by a factor of 4.0 when compared to the lower group. The baseline incidence increases with age and with time since exposure. Estimated baseline incidence rates were found to increase from 1988 to 1999 by factors of three and two for the upper and the two lower groups respectively. The estimated thyroid cancer incidence rates in Belarus and Ukraine, and their dependences on gender and age, are consistent with observed rates found in the larger cancer registries of other countries. In conclusion, the baseline cases are found to contribute about 70% to the thyroid cancer incidence in Ukraine, and about 40% to the incidence in Belarus.
Assuntos
Acidente Nuclear de Chernobyl , Neoplasias Induzidas por Radiação/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologia , Adolescente , Criança , Feminino , Humanos , Incidência , Masculino , Centrais Elétricas , Doses de Radiação , Sistema de Registros , República de Belarus/epidemiologia , Ucrânia/epidemiologiaRESUMO
The purpose of the present study was to analyze the thyroid cancer incidence risk after the Chernobyl accident and its degree of dependence on time and age. Data were analyzed for 1034 settlements in Ukraine and Belarus, in which more than 10 measurements of the (131)I content in human thyroids had been performed in May/June 1986. Thyroid doses due to the Chernobyl accident were assessed for the birth years 1968-1985 and related to thyroid cancers that were surgically removed during the period 1990-2001. The central estimate for the linear coefficient of the EAR dose response was 2.66 (95% CI: 2.19; 3.13) cases per 10(4) PY-Gy; for the quadratic coefficient, it was -0.145 (95% CI: -0.171; -0.119) cases per 10(4) PY-Gy(2). The EAR was found to be higher for females than for males by a factor of 1.4. It decreased with age at exposure and increased with age attained. The central estimate for the linear coefficient of the ERR dose response was 18.9 (95% CI: 11.1; 26.7) Gy(-1); for the quadratic coefficient, it was -1.03 (95% CI: -1.46; -0.60) Gy(-2). The ERR was found to be smaller for females than for males by a factor of 3.8 and decreased strongly with age at exposure. Both EAR and ERR were higher in the Belarusian settlements than in the Ukrainian settlements. In contrast to ERR, EAR increases with time after exposure. At the end of the observation period, excess risk estimates were found to be close to those observed in a major pooled analysis of seven studies of childhood thyroid cancer after external exposures.
Assuntos
Poluentes Radioativos do Ar/toxicidade , Acidente Nuclear de Chernobyl , Exposição Ambiental/análise , Neoplasias Induzidas por Radiação/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologia , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Carga Corporal (Radioterapia) , Criança , Pré-Escolar , Estudos de Coortes , Relação Dose-Resposta à Radiação , Feminino , Humanos , Incidência , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Centrais Elétricas , Prevalência , Doses de Radiação , Monitoramento de Radiação/métodos , Liberação Nociva de Radioativos , Sistema de Registros , República de Belarus/epidemiologia , Estudos Retrospectivos , Medição de Risco/métodos , Fatores de Risco , Distribuição por Sexo , Fatores de Tempo , Ucrânia/epidemiologiaRESUMO
In both medullary carcinoma and papillary carcinoma of the thyroid, altered expression of the RET gene is implicated in tumorigenesis. Recent studies suggest that loss of heterozygosity (LOH) at the G691S SNP may be associated with tumors from patients with a history of radiation exposure. We investigated LOH for three RET SNPs (G691S, S904S, and L769L) in tumor and normal tissue from 46 patients from Ukraine and Belarus who were exposed to radioactive fallout following the Chernobyl nuclear accident and were operated for papillary thyroid carcinoma between 1995 and 2000. Normal tissue from 28 patients was heterozygous for at least one SNP; DNA from the corresponding tumor samples was also heterozygous, indicating that no LOH had taken place. To assess SNP frequencies in a radiation-associated thyroid cancer cohort, we investigated a further 68 unpaired post-Chernobyl samples. For G691S, there was considerable deviation from Hardy-Weinberg equilibrium; more detailed analysis showed that this was linked to age at onset of disease. Among younger patients, the distribution of genotypes conformed to Hardy-Weinberg equilibrium; among older patients, we observed marked deviation (p = 0.0072), with significant over-representation of the rare S allele relative to the younger groups (Fisher's exact, p = 0.0233). This suggests that SNPs in the RET oncogene may play a role in sporadic papillary thyroid carcinoma.
Assuntos
Carcinoma Papilar/genética , Perda de Heterozigosidade , Neoplasias Induzidas por Radiação/genética , Proteínas Oncogênicas/genética , Polimorfismo de Nucleotídeo Único , Receptores Proteína Tirosina Quinases/genética , Neoplasias da Glândula Tireoide/genética , Adolescente , Adulto , Idoso , Acidente Nuclear de Chernobyl , Criança , Estudos de Coortes , Frequência do Gene , Ligação Genética , Humanos , Pessoa de Meia-Idade , Proteínas Proto-Oncogênicas c-ret , Cinza Radioativa/efeitos adversos , República de Belarus , UcrâniaRESUMO
The rate of childhood thyroid cancer incidence observed in northern Ukraine during the period 1986-1998 is described as a function of time-since-exposure, age-at-exposure, and sex. Conclusions are drawn for the excess absolute risk per dose: after a minimal latency period of about three years it shows a linear increase with time-since-exposure for at least nine years. It is roughly constant in age-at-exposure, up to 15 years. For girls exposed very young it is about a factor 2 larger than for boys. For children exposed at age 16-18 this ratio increases to about 5. The thyroids of young children are not more sensitive to radiation dose than those of older ones in absolute risk in northern Ukraine in the currently used data set. As the background is increasing with age, a constant absolute risk gives a decreasing relative risk.
Assuntos
Neoplasias Induzidas por Radiação/epidemiologia , Reatores Nucleares , Centrais Elétricas , Liberação Nociva de Radioativos , Neoplasias da Glândula Tireoide/epidemiologia , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Masculino , Risco , Fatores de Tempo , Ucrânia/epidemiologiaRESUMO
The moderately thermophilic acidophilic bacterium Sulfobacillus thermosulfidooxidans subsp. asporogenes strain 41 is capable of utilizing sulfides of gold-arsenic concentrate and elemental sulfur as a source of energy. The growth in the presence of S0 under auto- or mixotrophic conditions was less stable compared with the media containing iron monoxide. The enzymes involved in oxidation of sulfur inorganic compounds--thiosulfate-oxidizing enzyme, tetrathionate hydrolase, rhodonase, adenylyl sulfate reductase, sulfite oxidase, and sulfur oxygenase--were discovered in the cells of Sulfobacillus grown in the mineral medium containing 0.02% yeast extract and either sulfur or iron monoxide and thiosulfate. Cell-free extracts of the cultures grown in the medium with sulfur under auto- or mixotrophic conditions displayed activity of the key enzyme of the Calvin cycle--ribulose bisphosphate carboxylase--and several other enzymes involved in heterotrophic fixation of carbonic acid. Activities of carboxylases depended on the composition of cultivation media.
Assuntos
Ribulose-Bifosfato Carboxilase/metabolismo , Enxofre/metabolismo , Thiobacillus/crescimento & desenvolvimento , Meios de Cultura , Compostos Férricos/metabolismo , Oxirredução , Óxidos/metabolismo , Compostos de Enxofre/metabolismo , Thiobacillus/metabolismo , Tiossulfatos/metabolismoRESUMO
Sulfur oxygenase, sulfite oxidase, adenylyl sulfate reductase, rhodanase, sulfur:Fe(III) oxidoreductase, and sulfite:Fe(III) oxidoreductase were found in cells of aerobic thermoacidophilic bacteria Sulfobacillus sibiricus strains N1 and SSO. Enzyme activity was revealed in cells grown on the medium with elemental sulfur or in the presence of various sulfide elements and concentrates of sulfide ores. The activity of sulfur-metabolizing enzymes depended little on the degree of aeration during bacterial growth.
Assuntos
Bactérias/enzimologia , Enzimas/metabolismo , Enxofre/metabolismo , Meios de CulturaRESUMO
The thermoacidophilic iron-oxidizing chemolithotroph Sulfobacillus sibiricus N1T is characterized by steady growth and amplified cell yield when grown in vigorously aerated medium containing Fe2+, glucose, and yeast extract as energy sources. In this case, carbon dioxide, glucose, and yeast extract are used as carbon sources. Glucose is assimilated through the fructose-bisphosphate pathway and the pentose-phosphate pathway. Glyoxylate bypass does not function in S. sibiricus, and the tricarboxylic acid cycle is disrupted at the level of 2-oxoglutarate dehydrogenase. The presence of ribulose-bisphosphate carboxylase indicates that carbon dioxide fixation proceeds through the Calvin cycle. The activity of ribulose-bisphosphate carboxylase is highest in autotrophically grown cells. The cells also contain pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase.
Assuntos
Bacillus/enzimologia , Carbono/metabolismo , Carboxiliases/metabolismo , Bacillus/crescimento & desenvolvimento , Dióxido de Carbono/metabolismo , Ciclo do Ácido Cítrico , Meios de Cultura , Compostos Ferrosos , Frutose-Bifosfatase/metabolismo , Glucose , Via de Pentose Fosfato , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Fosfoenolpiruvato Carboxiquinase (GTP)/metabolismo , Piruvato Carboxilase/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismoRESUMO
In 66 patients carcinoma was formed on background of euthyroid multinodal goiter (MNG). There was established, that the malignant tumours in patients with euthyroid MNG in principal are the papillare thyroid carcinoma of a small size, do not invade the capsula of thyroid gland, that testifying relatively favourable course of the disease.
Assuntos
Carcinoma/complicações , Bócio Nodular/complicações , Neoplasias da Glândula Tireoide/complicações , Neoplasias da Glândula Tireoide/patologia , Feminino , Humanos , MasculinoRESUMO
The possibility of controlling endospore formation by changing cultivation conditions was for the first time shown in acidophilic chemolithotrophic bacteria Sulfobacillus thermosulfidooxidans type strain 1269 and the thermotolerant strain K1 formerly described as "S. thermosulfidooxidans subsp. thermotolerans". Suppression of sporulation occurred when these strains were cultured in Manning's liquid medium with yeast extract. This medium was optimized by gradually reducing the concentrations of ferrous iron salts (the source of energy), phosphorous, nitrogen, and yeast extract and simultaneously increasing the concentrations of calcium, magnesium, and manganese (the elements important for sporogenesis) to attain higher yields of endospores by strains 1269 and K1. As a result, a new medium A was proposed, in which the life cycle of the strains studied culminated in sporulation at a level of 45 and 60%, respectively, of the total cell number. In a series of additional tests, the growth temperature and medium pH were adjusted to obtain the maximum yield of endospores. The optimal ranges found were 40-50 degrees C and pH 1.8-2.2 for strain 1269 and 35-40 degrees C and pH 2.5-2.7 for strain K1. An even higher yield of endospores, amounting to 55 and 75% for strains 1269 and K1, respectively, was obtained when the above growth conditions were combined (growth on medium A at optimal temperatures and pH). Our results suggest a new approach to optimizing sporulation by acidophilic chemolithotrophs, which consists in limiting the energy and nutrient sources and using temperature and pH values within the tolerance bounds of these cultures but outside their growth of optimum ranges.
Assuntos
Bactérias Gram-Positivas Formadoras de Endosporo/fisiologia , Cálcio , Meios de Cultura , Concentração de Íons de Hidrogênio , Magnésio , Manganês , Esporos Bacterianos/crescimento & desenvolvimento , TemperaturaRESUMO
To determine enzymatic activities in the thermotolerant strain K1 (formerly "Sulfobacillus thermosulfidooxidans subsp. thermotolerans"), it was grown in a mineral medium with (1) thiosulfate and Fe2+ or pyrite (autotrophic conditions), (2) Fe2+, thiosulfate, and yeast extract or glucose (mixotrophic conditions), and (3) yeast extract (heterotrophic conditions). Cells grown mixo-, hetero-, and autotrophically were found to contain enzymes of the tricarboxylic acid (TCA) cycle, as well as malate synthase, an enzyme of the glyoxylate cycle. Cells grown organotrophically in a medium with yeast extract exhibited the activity of the key enzymes of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. An increased content of carbon dioxide (up to 5 vol%) in the auto- and mixotrophic media enhanced the activity of the enzymes involved in the terminal reactions of the TCA cycle and the enzymes of the pentose phosphate pathway. Carbon dioxide was fixed in the Calvin cycle. The highest activity of ribulose bisphosphate carboxylase was detected in cells grown autotrophically at the atmospheric content of CO2 in the air used for aeration of the growth medium. The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase decreased with the increasing content of CO2 in the medium.