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PubMed1983

Detection of melanomas. Approach with radiolabeled false precursors of melanin synthesis.

Thiouracil is a thiol-containing pyrimidine that is selectively incorporated into cells that synthesize melanin. In an effort to delineate further the specificity and dynamics of uptake, we injected thiouracil labeled with radioactive carbon into S91 melanoma-bearing mice; biopsy specimens were taken of the tumors and organs at various time intervals thereafter. The data showed a substantial uptake of thiouracil by the melanomas, with peak uptake occurring at 24 hours. All other organs examined showed only minor amounts of radioactivity, which probably reflected the presence of thiouracil in the blood perfusing these tissues. Because of its incorporation into melanomas, the use of radioactive thiouracil has potential as a marker for tumor growth, as a diagnostic tracer compound, and as a carrier for chemotherapeutic agents.

Animals↗

PubMed2005

Use of dual isotope tracers in biomedical research.

Biomedical stable isotope studies involve administration of tracer and measurement of isotope enrichment in blood, urine, feces or breath. The aim of the studies is to gather quantitative information about a specific metabolic function. However, the measured isotope enrichment may be affected by other metabolic events than only this function. In this case, a correction is necessary. The best approach is to add a second tracer simultaneously which is known to be metabolised by all interfering metabolic events but not by the function of interest. This dual isotope approach also enables simultaneous measurement of two interrelated functions. A summary of selected applications involving dual isotope tracer studies is presented. The applications deal with energy expenditure (doubly labelled water technique), cholesterol absorption, starch and lactose digestion, fat digestion, bile acid metabolism and the combination of stable and radioactive carbon isotopes in breath testing.

Bile Acids and Salts↗

PubMed2006

Energy integration between the solitary polyps of the clonal coral Lobophyllia corymbosa.

Clonal integration in the coral Lobophyllia corymbosa was studied from two perspectives: transfer of carbon among clonemates and allorecognition. This coral forms colonies in the early post-metamorphic stages. In later ontogeny, the tissues interconnecting polyps die, transforming the colony into a clone of solitary polyps. These polyps continue to live in close proximity but without tissue continuity. Isolated polyps labeled with radioactive carbon in the light showed oriented transfer of assimilates towards adjacent, injured polyps. No significant transfer of carbon was observed towards intact, isogeneic polyps or allogeneic polyps. Grafting of coral tissues resulted in intra-clonal fusion, but only when polyps were previously sectioned. Allogeneic sectioned grafts were always rejected. Intact polyps were unresponsive towards isogeneic and allogeneic counterparts when grafted. Our results show that isolated Lobophyllia polyps not only recognize their clonemates as such, but also help them when necessary, although no tissue continuity exists between them.

Animal Communication↗

PubMedDate not supplied

Prevention by ulinastatin of decreased carbonic anhydrase activity induced by PMN elastase in vitro.

Disturbed carbon dioxide (CO2) elimination in adult respiratory distress syndrome (ARDS) has been considered to result from the dead space created by microthrombosis and vasoconstriction. However, another disturbance factor in CO2 elimination has been reported; the chemical dead space resulting from the inhibition of carbonic anhydrase (CA). This experiment was conducted to quantify the inhibition of CA activity by polymorphonucleocyte (PMN) elastase, which increases in ARDS. Different flasks containing solutions of CA, buffer, elastase, ulinastatin (an elastase antagonist), CA with PMN elastase, and CA with both PMN elastase and ulinastatin were prepared. Each flask was injected with sodium bicarbonate labeled with radioactive carbon (14C) and was shaken for 20 minutes; CA activity in each flask was measured by calculating the decrease in the coefficient (K) of 14C. It was observed that CA activity was inhibited dose-dependently by PMN elastase and that the inhibited activity was recovered by ulinastatin, which can inhibit PMN elastase. These findings indicate that CA activity in vitro could be inhibited by PMN elastase, which increases in ARDS, and suggests that disturbance of CO2 elimination could be reduced by using ulinastatin. It was concluded that ulinastatin could prevent the CA activity induced by PMN elastase in vitro.

Carbonic Anhydrase Inhibitors↗

PubMed1988

Tissue and chain length specificity of the fatty acyl-CoA elongation system in the American cockroach.

The elongation of fatty acyl-CoAs, reactions involved in hydrocarbon biosynthesis, was examined in the cockroach, Periplaneta americana. Products were analyzed by radio-HPLC and radio-GLC. The majority of the elongation activity was observed in microsomes prepared from abdominal epidermal tissue. Linoleoyl-CoA (18:2-CoA) was elongated most efficiently followed by stearoyl-CoA (18:0-CoA), linolenoyl-CoA (18:3-CoA; n-3) and oleoyl-CoA (18:1-CoA). The products of 18:2-CoA elongation included all even numbered acyl groups up to 28 carbons, and the products of 18:0-CoA included all even numbered acyl groups to 26 carbons. The 18:3-CoA was elongated only to 20 and 22 carbons. Radioactivity from both 18:2-CoA (5.4%) and 18:0-CoA (1.2%) was recovered in the hydrocarbon fraction. Analysis of this hydrocarbon fraction showed that the radio-activity from 18:2-CoA was present in (Z,Z)-6,9-heptacosadiene and that the radioactivity from 18:0-CoA was present in n-pentacosane. These data demonstrate for the first time in an in vitro insect system that the fatty acid elongation reactions are coupled with the conversion of the elongated product to hydrocarbon. Thus, each of the expected intermediates in the conversion of 18:0 and 18:2 to 25 and 27 carbon hydrocarbons, respectively, was observed, and the results demonstrate high tissue, substrate, and product specificity.

Acyl Coenzyme A↗

PubMedDate not supplied

Photosynthesis: a short history of some modern experimental approaches.

This paper presents a personal interpretation of a chapter of plant physiology beginning from the early 1930s to the early 1940s, when plant physiologists tried to find the missing link between the two (dark and light) phases of photosynthesis. As initially inferred by Richard Willstätter and Arthur Stoll in the 1910s, and then stated by Robert Emerson and William Arnold in 1932, the most accredited theory proposed that carbon dioxide must combine with chlorophyll in the dark. Successive light flashes activated the complex chlorophyll-carbon dioxide with oxygen evolution, and carbon dioxide was reduced to formaldehyde and successively polymerised into hexose. Arthur Stool in 1932 and Cornelius v. Niel in 1935 gave the first stroke to this theory suggesting that carbon dioxide must be reduced and assimilated by means of a process of water oxidation. Robert Hill showed the existence of an indissoluble link between the light phase, water oxidation and possibly oxygen evolution. Two physicists, Sam Ruben and Martin Kamen proposed the assembly of photosynthesis into a unitary process occurring as a sequence of several steps in the first 1940s. By utilising for the first time radioactive carbon (11C), they elaborated a new theory according to which carbon dioxide reduction was a repeated "cyclic" mechanism. This "heretical" view abolished the old, but still considered, theory of formaldehyde. Hill, Ruben and Kamen were able to exploit at best the possibility offered by a very advanced technology, thus confirming once again that ideas stand upon the powerful legs of technology.

Botany↗

PubMed1984

Amino acids labelled with 11C as indicator of the effect of dietary treatment of hyperammonaemia.

Short-lived radioactive carbon, 11C, (T 1/2 = 20 min) was incorporated into an essential amino acid [11C-methyl] -L-methionine, to form a true biological amino acid tracer with external detectability. This was tested in a study of the physiological tracer dynamics in a hyperammonaemic patient before and after a change in the dietary treatment. The protein intake was unchanged between the two investigations but the energy intake was increased from 53 to 63 kcal/kg BW/day. The tracer radioactivity was given per os. In the second investigation a relative decrease of radioactivity in the low molecular weight fraction of blood plasma was seen. Also the external measurements indicated a higher hepatic retention of radioactivity in the second investigation but no increased excretion of tracer. This may reflect an increased ability of the liver to utilize the incoming methionine from the vena porta. The hyperammonaemia remained over the second investigation but seven months later the ammonia content in the blood was almost normalized and the patient had also gained 3 kg in weight. The correlation between changes in tracer dynamics and changes in therapeutical effect of the diet is not further verified in this experiment but the investigation indicates the value of further studies in this topic using 11C-labelled amino acids also including the use of the newly introduced positron tomographic technique. It may be possible to develop this type of nuclide technique further to achieve a clinically useful method of optimizing therapeutic regiments in this type of metabolic disease.

Amino Acid Metabolism, Inborn Errors↗

PubMed1979

[Autoradiographic determinations of carbon-14-labeled monomers and residual monomers in the tissues of Wistar rats after implantation of cold-polymerizing polymethyl methacrylate (bone cement) (author's transl)].

Self-setting acrylics, named bone cement, are taken for the reconstruction of bone defects, for the fixation of endothesis and fractures. A disadvantage of these rapid-cure acrylic compounds is the toxicity of its monomer. Infraredspectrographic measurements showed an absolute content of 12,3 per cent monomer in an acrylic-resin-compound-implant. In order to perseive the incorporation of the diffused monomer after implantation of bone cement in rats, the monomer were marked with 14C (radioactive carbon). The autoradiographic examination revealed the excretion of the marked monomer in the urine and an accumulation in kidney, liver and lungs. The results were demonstrated.

Acrylic Resins↗

PubMed1975

Effect of hydrofluoric acid on glucose metabolism of the mouse studied by whole-body autoradiography.

Distribution of radioactive carbon from [U-14C]glucose in the mouse poisoned by hydrofluoric acid has been studied by whole-body autoradiography. Under normal conditions, the highest autoradiographic density was found in the Harder's gland, palatine gland, sublingual gland, large intestinal mucosa, and many regions of the central nervous system 30 minutes after intraperitoneal injection of [U-14C]glucose. On the other hand, after hydrofluoric acid poisoning, it was found that (1) the radioactivity of brain was unchanged throughout all the poisoning; (2) the liver, renal cortex, lung, and blood showed an increase in radioactivity at 180 minutes of poisoning; (3) the abdominal cavity showed a tendency to residual radioactivity with the poisoning; (4) by contrast, Harder's gland, the palatine gland, sublingual gland, and large intestinal mucosa showed a decrease in radioactivity at 180 minutes of poisoning.

Acids↗

PubMed1993

Incorporation of carbon atoms from glucose into the food mutagens MeIQx and 4,8-DiMeIQx using 14C-labelled glucose in a model system.

Mixtures of creatinine, glucose and threonine with the addition of a small amount, 250 microCi, of [U-14C]glucose, [1-14C]glucose or [6-14C]glucose were heated at 180 degrees C for 30 min in an aqueous model system. The mixtures were purified and analysed using HPLC, scintillation and Ames tests. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were detected as the main radioactive mutagens. The amount of MeIQx and 4,8-DiMeIQx produced from threonine was estimated at 18 and 60 nmol/mmol glucose respectively. Radioactive carbon atoms originating from glucose were also shown to be incorporated into 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx). The specific activity was calculated to be 0.6, 0.3 and 0.1-0.3 mCi/mmol for MeIQx, 4,8-DiMeIQx and IQx respectively for all three labelled forms of glucose. By the incorporation of carbon atoms originating from glucose into the imidazoquinoxaline mutagens it was clearly demonstrated that glucose is a precursor in the formation of these food mutagens.

Carbon↗

PubMed1977

Relations between Light Level, Sucrose Concentration, and Translocation of Carbon 11 in Zea mays Leaves.

The mechanism of carbon transport in Zea mays leaves was investigated using carbon 11 which is a short lived (half-life 20.4 min) positronemitting isotope. The gamma radiation produced on annihilation allows in vivo or nondestructive measurement of the isotope and the short half-life allows many measurements of translocation to be made on the same leaf within the same day.Carbon 11 produced by the (10)B (d,n)(11)C nuclear reaction was converted to (11)CO(2), fed to a leaf as a short pulse, and assimilated during photosynthesis. The progress of the radioactive pulse along the leaf in the phloem was monitored in several positions simultaneously with counters. The counters were NaI crystals with photomultipliers and the output was amplified, passed to single channel analyzers, and the counts accumulated for 20 seconds every 30 seconds. Corrections were made for the half-life and background radiation by computer, and the results were displayed on a high speed plotter. Information derived from the corrected data included the speed of translocation, the shape of the radioactive carbon pulse, and the influence of light and distance along the leaf on these parameters. The plants were kept under controlled environment conditions during all measurements.A speed was derived from the time displacement of the midpoint of the front of the pulse, measured at two positions along the leaf. This was an apparent mean speed of translocation because it averaged a variation in speed with distance, variation in speed between or within sieve tubes, and it averaged the mean speed of all of the particles in the pulse.A wide range of speeds of translocation from 0.25 to 11 cm min(-1) was observed but most of the variability was due to the variation in light available to the leaf. For example, the speed of translocation was proportional to the light level on either the whole plant or individual leaf. Shading of the leaf established that the light effect was not localized in either the feeding area or in the portion of the leaf on which the measurements were made. It was proposed that the speed was dependent on the proportion of the leaf in the light upstream from the last counter. The speed of translocation was relatively independent of the stage of growth of the plant, age of the leaf, and the time during the diurnal light cycle.Data obtained on the level of the reducing sugars, starch, and sucrose in the leaf were related to the speed of translocation. A biphasic relationship between speed and sucrose concentration in the leaf was established and the high speeds measured during experiments only occurred when sucrose concentrations in the leaf exceeded 8% of the dry weight.The shape of the pulse loaded into and translocated in the phloem was estimated from the half-width of the pulse. The half-width was primarily determined by loading phenomena which resulted in an increase in the half-width from 2 minutes when fed to the leaf to more than 40 minutes in the phloem. In many examples, the pulse continued to broaden with distance along the leaf from the fed region. The half-width was independent of the speed but highly dependent on the light level.

Journal Article↗

PubMed2004

Productivity and growth of a natural population of the smallest free-living eukaryote under nitrogen deficiency and sufficiency.

The influence of dissolved inorganic nitrogen (DIN) enrichments on cell-normalized carbon uptake rate, chlorophyll a content, and apparent cell size of a picoeukaryote (<1 microm) ( Ostreococcus tauri, the smallest eukaryotic cell) from a natural summer phytoplanktonic assemblage (<200 microm) in a northern Mediterranean Lagoon (Thau Lagoon) was studied in 20-L enclosures in June 1995. The natural planktonic community was incubated in situ for 24 h with initial ammonium and nitrate enrichments and compared to a control without enrichment. O. tauri cell-normalized productivity was estimated from the combination of flow cytometric (FCM) enumeration and 2-h (radioactive) carbonate incorporation measured on post-incubation size fractions (<1microm). No difference between the effects of the two DIN sources of enrichment on the studied biological parameters was measured during this experiment. Growth of natural O. tauri was perturbed by the low DIN availability in the control with drastic changes in cell productivity, chlorophyll content, and cell cycle (from the variations in apparent cell size) as compared to the DIN sufficiency conditions. On the other hand, a very high specific growth rate for natural O. tauri, up to 8 day(-1) under DIN enrichments, has been estimated from production and abundance data obtained during this experiment. This supports values measured in culture and suggests that the yearly high contribution of picophytoplankton to the total primary production in Thau Lagoon is likely to be due to their high growth rate rather than the previously suggested lack of grazing pressure.

Carbon↗

PubMed1988

Sequential intrahepatic metabolic effects of enteric galactose alimentation in newborn rats.

We determined metabolic responses after enteric galactose alimentation in 5- to 7-day-old newborn rats fasted for 24 h. The glycemic response was attenuated after enteric galactose feeding compared with the response after enteric glucose-fed rat pups. 14C radioactivity in blood from galactose-fed pups was reduced as counts in blood galactose were lower than counts in blood glucose in glucose-fed pups. Nonetheless within 15 min, [14C] from galactose appeared in blood glucose suggesting rapid conversion of galactose to glucose. The plasma insulin response was also attenuated after galactose feeding compared with the insulin response after enteric glucose. Hepatic glycogen content increased rapidly after enteric galactose feeding and was higher than after glucose feeding at 60, 120, and 180 min. Significant glycogen synthesis after oral glucose was delayed and occurred at 240 min. Carbon radioactivity in glycogen was higher in galactose fed pups between 15 and 360 min of the study. Serial determination of hepatic metabolites revealed an increase of galactose-1-phosphate levels after oral galactose at 240 and 300 min and a transient decline of ATP at 15 min. Other hepatic metabolites did not demonstrate significant differences between the two groups. These data suggest that hepatic glycogen synthesis is more rapid and occurs sooner after galactose than after glucose alimentation in previously fasted newborn rats. Galactose may enter a more direct pathway for neonatal hepatic glycogen synthesis. The relatively delayed entry of glucose label into hepatic glycogen and the delay of net glycogen synthesis after oral glucose suggest that glucose entry is not direct and may require further metabolism before incorporation into glycogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Main routes of plasma lactate carbon disposal in the midgestation fetal lamb.

The turnover rates of plasma lactate, normalized for O2 consumption rate, are higher in the fetus than in the adult. This occurs despite very low rates of fetal gluconeogenesis which preclude the recycling of lactate carbon into glucose. In an effort to establish the main routes of disposal of fetal plasma lactate, 12 midgestation ovine fetuses (age 74 +/- 1 days) were infused intravenously at constant rate with L-[U-14C]lactate for a 4-hour period. At the end of the infusion, the amounts of 14C retained by the fetus and by the placenta, and the distribution of the retained 14C in free and protein-bound amino acids and in lipids were measured. Of the total 14C infused, 17.0 +/- 1.4% was recovered in the placenta, 4.0 +/- 0.3% in the fetal liver, and 15.0 +/- 0.8% in the extrahepatic fetal tissues. Of the retained radioactive carbon, 45-57% was recovered in the free and protein-bound amino acid fractions and 11-17% in the lipid fractions. Approximately 90% of the 14C in the free amino acid fractions was present as glutamate/glutamine, serine, glycine, and alanine carbon. In conjunction with data on fetal CO2 production from lactate carbon, these results demonstrate that the main routes of fetal lactate disposal are oxidation and synthesis of nonessential amino acids and lipids.

Amino Acids↗

PubMed1975

Regulation of carbohydrate metabolism in lymphoid tissue. Quantitative aspects of [U-14C]glucose oxidation by rat spleen slices.

When washed spleen slices from fed rats are incubated with 3 mm-[U-14C]glucose, the rate of glucose utilization (46.2 mumol/h per g dry wt.) is sufficient to account, theoretically, for 80% of the O2 consumption. Measurement of net lactate production, however, and the fate of the radioactive carbon, indicates that the contribution of glucose to the respiratory fuel of the tissue is only 25-30% whereas 60-70% of the glucose utilized is converted into lactate. At saturating glucose concentrations (above 5 mm) its contribution to the respiratory fuel of the slice is increased to a maximum value of 34-39%. Only 2% of the glucose utilized is metabolized via the oxidative steps of the pentose phosphate pathway. Starvation for 72 h marginally increases both the rate of glucose utilization (by 21%) and its net contribution to the respiratory fuel (by 29%). Insulin, glucagon, adrenaline and adenosine 3':5'-cyclic monophosphate have no significant effect on either the rate of glucose utilization or on the pattern of radioactive isotope distribution. The uptake of glucose is increased by only 20%, whereas the production of lactate doubles when slices are incubated under anaerobic conditions. In assessing the suitability of spleen slices for metabolic studies, the only serious major perturbation, compared with the freeze-clamped organ, is an elevated mitochondrial [NAD+]/[NADH] ratio (connected with increased endogenous NH3 production) that is partially restored to normal values on incubation with glucose. Equal proportions of erythrocytes and leucocytes are found in the washed spleen slice. Metabolic contributions of the constituent cell populations in the washed slice are calculated and it is concluded that lymphocytes account for the major part of the glycolytic metabolism (80-90%), whereas the contribution of erythrocytes is insignificant.

Adenosine Diphosphate↗

PubMed1990

Utilization of labeled thymidine in DNA synthesis: studies for PET.

Carbon-111-thymidine and positron emission tomography (PET) have the potential for noninvasively measuring DNA synthesis in tumors and tissues. In order to validate this potential, one needs to construct accurate biochemical models that reflect the metabolism of thymidine, including its uptake and degradation as well as its incorporation into DNA. Our studies employed thymidine labeled in the methyl position using 11C, 14C, and 3H. Studies with rapidly proliferating tissues of mice demonstrated that most of the activity, 60 min after injection of labeled thymidine, was present in DNA, with smaller amounts found in metabolites. Studies in dogs, however, reveal that more activity was present in metabolites, rather than in the DNA of tumors and spleen tissue. HPLC analysis of canine blood after the injection of thymidine revealed rapid conversion of thymidine to thymine and other metabolites. We have found significant differences in the metabolism of [3H]thymidine versus thymidine labeled with radioactive carbon. These differences, which were not found when comparing 14C and 11C, indicate that [3H]thymidine is not an appropriate standard for comparison with PET studies employing [11C] thymidine. To accurately interpret images of [11C]thymidine as representations of DNA synthesis we are developing kinetic models that take into account the metabolism of thymidine and the contribution of degradation products to the 11C images.

Animals↗

PubMed1997

Carbon monoxide contributes to the cytokine-induced inhibition of surfactant synthesis by human type II pneumocytes.

BACKGROUND: An increase in cyclic guanosine 3',5'-monophosphate (cGMP) due to nitric oxide generation is known to participate in the mediation of the tumor necrosis factor alpha (TNF-alpha) effect in type II cells. Because guanylyl cyclase can be activated also by carbon monoxide (CO), in this study we examined the ability of human type II pneumocytes to produce CO in the presence of cytokines and the relative contribution of this molecule to the TNF-alpha and interleukin 1 effects. DESIGN: Type II pneumocytes were isolated from cadaveric multiple-organ donors by enzymatic digestion, adherence separation of macrophages, and gradient purification. After preculture for 24 hours, cells were cultured for 24 hours in the presence or absence of TNF-alpha, interleukin 1, sodium nitroprusside, N(omega)-nitro-1-arginine, CO, hemin, zinc-protoporphyrin type IX, deferoxamine mesylate, S-adenosyl-L-methionine, alpha-tocopherol, methylene blue (a guanylyl cyclase inhibitor), 8-bromine-cGMP, and combinations of these reagents. Both CO (picomole per microgram of protein) and nitric oxide release to the medium and the cGMP (picomole per microgram of protein) content of the cells were measured. In a different set of experiments, D-glucose labeled with radioactive carbon (14C) was added to the medium, and the labeling of several lipid fractions was determined (picomole per microgram of protein). RESULTS: D-[14C]glucose incorporation into phosphatidylcholine, the main surfactant component, was selectively inhibited in the presence of cytokines, CO, sodium nitroprusside, or 8-bromine-cGMP. The inhibitory effect of TNF-alpha was partially reversed by N(omega)-nitro-L-arginine, deferoxamine, or alpha-tocopherol and totally reversed by methylene blue. Tumor necrosis factor alpha induced an increase in cGMP cell content and in the CO and nitric oxide release to the medium. Hemin increased CO and cGMP production and decreased phosphatidylcholine synthesis. Zinc-protoporphyrin type IX, an inhibitor of heme oxygenase, and all 3 antioxidants, which inhibited CO production, also antagonized the TNF-alpha effect on cGMP and phosphatidylcholine synthesis. CONCLUSIONS: Intracellular cGMP increase due to an endogenous generation of both CO and nitric oxide mediates the cytokine-induced inhibition of surfactant synthesis by type II pneumocytes. Both lipid peroxidation and heme oxygenase activity are sources for the observed CO production.

Adolescent↗

PubMed1964

Life and space.

The studies dealing with the detection of life on planets and in space will have two periods. The first period will be associated with the application of automatical devices, which will detect living creatures, whereas the second, more late, period will be concerned with the investigations provided by man himself. In these studies one should proceed from the idea of life on the Earth, and, consequently, look for living creatures containing no water, no carbon dioxide, etc. only after obtaining negative results in searching for creatures similar to those living on the Earth. The whole course of "chemical evolution" on the Earth proves the necessity of the detection on other planets of heterotrophic microorganisms at first, and only afterwards to look for specialized forms, i.e. chemo- and photoautotrophs. It is usually underestimated that as a result of adaptation to certain ecological conditions existing on planets living creatures may appear, which will distinctly differ in their biological properties from terrestrial forms. At present there is no faultless investigation which is able to prove to existence of cosmobionts in meteorites. The appropriate experiments convince us that soil bacteria. may penetrate into the central parts of meteorites, which have been lying in the ground. Samplings at high altitudes with the aid of aerostats or the rockets are difficult to provide because of the possibility of pollution of samples by terrestrial microbes. It is therefore necessary to elaborate special devices and new methods for sampling. The most perfect instrument for the detection of microorganisms will be a device, which will record the multiplication rate of microbes in the liquid media simultaneously by means of different methods: manometry, nephelometry, potentiometry and the determination of radioactive carbon dioxide which is extracted during the breakdown of organic substances.

Atmosphere↗