Analysis of the mechanism of intensification of fermentation process using yeast cells in a suspension of high-dispersed oxides

The differential microcalorimetry was used to explore an influence of particles of silicon dioxide, and also other high-dispersed oxides (0.05% of masses.) in water suspension of yeast cells on intensification of the process of their fermentation in endogenous metabolic conditions. It was shown that intensification of the processes of the vital activity of yeast microorganisms was observed in the specified interval of the concentration of silicon dioxide hydrosol particles. Mechanisms of interaction between SiO₂ particles and a surface of a cellular organism, as well as interaction between SiO₂ particles and one of metabolism products — carbon dioxide were studied. It was found out, that Al₂O₃, TiO₂ hydrosols also had a stimulating effect, but it is lower compared to that of SiO₂.     

Validation of manometric microrespirometers for measuring oxygen consumption in small arthropods

Scientists have used numerous techniques to measure organismal metabolic rate, including assays of oxygen (O(2)) consumption and carbon dioxide (CO(2)) production. Relatively few studies have directly compared estimates of metabolic rate on the same groups of animals as determined by different assay methods. This study directly compared measures of the metabolic rate of three lines of Drosophila simulans as determined either from direct measures of CO(2) production using infrared gas analysis (IRGA), or from estimates of O(2) consumption based on manometeric techniques. Determinations of metabolic rate of the same cohorts of flies using these two methods produced results that often differed widely. Typically metabolic rate as determined by the manometric method was significantly greater than that determined by CO(2) output. These differences are difficult to explain by simple biotic or abiotic factor(s). Because of the idiosyncratic nature of these differences it is not possible to use a simple factor to convert from metabolic rate measurements done using manometric techniques to those expected from direct measures of CO(2) output or O(2) consumption. Although manometric devices are simple to construct and use, measurements of metabolic rate made with this method can vary significantly from measurements made by directly assaying CO(2) production or O(2) consumption.     

Role of macrophage destruction products in the alveolar phagocytosis reaction]

Peritoneal macrophages (PM) of Wistar rats harvested after the intraperitoneal injection of paraffin oil were destroyed by repeated freezing-thawing. When injected intratracheally to control rats or to those after 4 daily exposured to TiO2 dust, these macrophage destruction products (MDP) caused a significant rise of both the alveolar macrophages (AM) and the neutrophilic leukocytes (NL) counts in the pulmonary washing-outs; the mean NL/AM ratio increased several times as compared to rats injected with normal saline intratracheally. Thus, the response to the inert dust particles plus the exogenous MDP became similar to the one observed after the cytotoxic (for instance silica) particles inhalation. Enhancing the NL contribution to the inhaled particles phagocytosis, the MDP led to a significant decrease of the mean "Dust load" of a single AM, although the total number of the engulfed particles increased. The predominant attraction of granulocytes and particularly of the NL as compared to the peritoneal macrophages was also found in the peritoneal exudates of rats injected with the MDP or silica suspension intraperitoneally, while the alveolar phagocytosis was not influenced. In vitro the MDP was shown to stimulate the NL migration and to facilitate the O2 consumption by PM. A possible role of the MDP as a multipotent controlling factor of phagocytosis response is briefly discussed.     

Preparation and characterization of Pluronic-colloidal silicon dioxide composite particles as liquid crystal precursor

The purpose of this study was to produce spray-dried Pluronic-colloidal silicon dioxide (Aerosil) composite particles as a liquid crystal precursor that would form a liquid crystalline phase upon hydration. A Pluronic-colloidal silicon dioxide dispersion in isopropyl alcohol was spray-dried to obtain composite particles using different concentrations of Aerosil. Polarizing microscopy, gelation, gel melting, and rheological studies were employed to characterize the composite particles. The composite particles obtained were irregular, with concave depression. Gelation was found to decrease with the addition of Aerosil, while gel melting was found to increase with the concentration of Aerosil. Rheological studies showed an increase in elasticity as well as viscosity with an increase in the concentration of Aerosil. Composite particles showed improved gelation and rheological properties. These composite particles and the process by which they were obtained may be useful for designing various drug delivery systems.     

Analysis of the effects of nitric oxide and oxygen on nitric oxide production by macrophages

The interactions between NO and O(2) in activated macrophages were analysed by incorporating previous cell culture and enzyme kinetic results into a novel reaction-diffusion model for plate cultures. The kinetic factors considered were: (i) the effect of O(2) on NO production by inducible NO synthase (iNOS); (ii) the effect of NO on NO synthesis by iNOS; (iii) the effect of NO on respiratory and other O(2) consumption; and (iv) the effects of NO and O(2) on NO consumption by a possible NO dioxygenase (NOD). Published data obtained by varying the liquid depth in macrophage cultures provided a revealing test of the model, because varying the depth should perturb both the O(2) and the NO concentrations at the level of the cells. The model predicted that the rate of NO(2)(-) production should be nearly constant, and that the net rate of NO production should decline sharply with increases in liquid depth, in excellent agreement with the experimental findings. In further agreement with available results for macrophage cultures, the model predicted that net NO synthesis should be more sensitive to liquid depth than to the O(2) concentration in the headspace. The main reason for the decrease in NO production with increasing liquid depth was the modulation of NO synthesis by NO, with O(2) availability playing only a minor role. The model suggests that it is the ability of iNOS to consume NO, as well as to synthesize it, that creates very sensitive feedback control, setting an upper bound on the NO concentration of approximately 1 microM. The effect of NO consumption by other possible pathways (e.g., NOD) would be similar to that of iNOS, in that it would help limit net NO production. The O(2) utilized during enzymatic NO consumption is predicted to make the O(2) demands of activated macrophages much larger than those of unactivated ones (where iNOS is absent); this remains to be tested experimentally.     

Indirect estimation of cell mass and substrate concentration using a computer-coupled mass spectrometer

On-line estimation of cell mass and substrate concentration based on exhaust gas analysis was developed. The O₂, CO₂, H₂O, and N₂ contents at the inlet and outlet of fermentor, analyzed by a computer-coupled quadrupole mass spectrometer, were used to calculate the oxygen uptake rate and carbon dioxide evolution rate, and these rates were further used to evaluate cell mass and substrate concentration in a recombinant Escherichia coli fermentation. Cell mass, glucose concentration, specific growth rate, and specific consumption rate of glucose were well estimated by this method; the oxygen uptake rate gave more accurate estimates for these state variables than did the carbon dioxide evolution rate.     

Formation of active forms of oxygen by rat peritoneal macrophages under the effect of cytotoxic dust]

The velocity of superoxide radicals (O2) production by rat peritoneal macrophages, phagocyting the dust particles (quartz and crocidolite-asbestos was measured by using the method of cytochrome c reduction. Generation of hydroxyl radicals (HO) by cells and intensity of lipid peroxidation in the membranes of phagocytes were also investigated. It was found, that under the action of quartz the cells form mainly O2, and under the action of crocidolite--O2 and HO(.). The differences observed were caused by catalytic properties of the surface of asbestos fiber, where the reaction of HO. formation from O2 takes place. The quartz particles increased the concentration of malondialdehyde in macrophages by 53% as compared with control; and lipid peroxidation intensity in the presence of crocidolite-asbestos fibers increased fourfold. The role of hydroxyl radicals in initiating of lipid peroxidation, cytotoxicity and mutagenicity of asbestos is discussed.     

Solubility of nickel oxide particles in various solutions and rat alveolar macrophages

The solubility of five types of commercial nickel oxide particles was determined in different types of solutions, including distilled water, physiological saline, buffered saline, and tissue-culture medium, in order to estimate their solubility in the human respiratory tract. In addition, we examined the solubility of the two types of particles that were the most and least soluble particles of the above five types of nickel oxide, in rat alveolar macrophages cultured in vitro. The solubility of the nickel oxide particles in these solutions varied remarkably with their types, suggesting that, even though they are called as “nickel oxide,” their solubilities are different among the manufacturer and the product lot. Their solubilities were also influenced by the types of solution and the existence of carbon dioxide in the atmosphere. The solubility of nickel oxide particles in the alveolar macrophages was significantly larger than that observed in the culture medium without macrophages, but smaller than that observed in the distilled water. These results suggest that the actual solubility of nickel oxide particles in the respiratory tract may be difficult to estimate by the conventional solubility analysis method using distilled water, and that the enhancement of particle dissolution by the alveolar macrophages and the depression of particle solubility by the coexisting salt and carbon dioxide should be taken into consideration for the accurate estimation.     

Mechanochemical solubilization of silicon dioxide with polyphenol compounds of plant origin

Mechanochemical interaction of an amorphous silicon dioxide with catechins of plant origin was used for silicon dioxide solubilization at neutral pH. Mechanism of polyphenol interaction with silicon dioxide was suggested based on investigation of kinetics of solubilization of ‘silicon dioxide-catechol’ model system that included an interaction of hydroxyl groups on the surface of silica with polyphenols, formation of surface complexes, and solubilization of these complexes. Mechanochemical treatment of catechol—natural catechin of plant origin—with amorphous silicon dioxide resulted in an increase of the solubilization rate due to chelate complex formation.     

Interleukin 1 production and accessory cell function of rat alveolar macrophages exposed to mineral dust particles

Immunostimulatory effects of respirable mineral dust particles on alveolar macrophages (AM) and T lymphocytes were tested in vitro. When rat AM were incubated with fibrogenic silica and asbestos particles, a significant interleukin 1 (IL-1) activity was generated into the culture supernatants, whereas neither AM alone nor AM incubated with non-fibrogenic titanium dioxide (TiO2) particles, however, produced a detectable amount of IL-1. Interleukin 2 (IL-2) activity, as tested with IL-2-dependent CTLL-2 assays, was not detectable from all of these cultures. It was also revealed that concanavalin A-induced proliferation of T lymphocytes was enhanced in autologous AM and nylon wool-passed spleen cell co-cultures incubated only with fibrogenic particles, but not with non-fibrogenic particles. Higher IL-1 activity was detected only from co-cultures exposed to fibrogenic particles, whereas IL-2 activity was almost similar among these co-cultures. These results indicate the differences in immunostimulatory effects on pulmonary macrophages and T lymphocytes among a variety of mineral dust particles.     

Transmembrane potential variations accompanying the PMA-triggered O-2 and H2O2 release by mouse peritoneal macrophages

Stimulation by PMA of Streptococci-elicited macrophages induced a transient membrane depolarization preceding the onset of detectable O-2 production. Mice-resident peritoneal macrophages were unresponsive to PMA for both activities. The PMA-triggered membrane depolarization seemed to be independent from O-2 production because inhibition of membrane depolarization by EGTA had no effect on rates of O-2 or H2O2 release and rate of antimycin A insensitive O2 uptake by Streptococci-elicited macrophages. The portion of O2 uptake recovered as O-2 was found to be 1/3. The rate of O-2 release was twice the rate of H2O2 production (1.1 nmol H2O2.min-1 X 10(6) macrophages-1).     

Molecular basis of macrophage activation. Expression of the low potential cytochrome b and its reduction upon cell stimulation in activated macrophages

The expression of the novel b-type cytochrome, which is part of the superoxide anion (O2-)-generating system in phagocytes, has been investigated in population of mouse peritoneal macrophages heterogeneous in their capability to produce O2-). Reduced minus oxidized difference spectra of intact cells showed the appearance of a b-type cytochrome with major peaks in the alpha region at 558 to 559 nm and in the gamma region at 426 to 428 nm. Resident peritoneal macrophages, as well as thioglycollate broth-elicited and Corynebacterium Parvum-activated macrophages and neutrophils expressed about 50 pmol cytochrome b/10(7) cells. In intact macrophages and neutrophils, Na-dithionite reduced greater than 75% of the cytochrome b measurable in disrupted cells. No correlation was found between capability to produce O2-) by different population of macrophages and their content of cytochrome b. When stimulated in strictly anaerobic conditions with phorbol myristic acetate, macrophages activated in vivo by i.p. injection of Corynebacterium Parvum reduced approximately 40% of their total cytochrome b. In resident peritoneal macrophages that produced five times lower amounts of O2-, cytochrome b reduction was instead undetectable. Potentiometric properties of cytochrome b was investigated in macrophage subcellular particles. Both resident and Corynebacterium Parvum-activated macrophages revealed the presence of b chromophores with very low potentials of -255 and -244 mV, respectively, whose content was not different in the two populations. These results show that resident and activated macrophages express the same amount of cytochrome b, but upon stimulation with PMA, activated macrophages recruit a higher number of cytochrome b molecules in parallel with an enhanced production of O2-.     

Salmonella-typhimurium-specific difference in rate of intracellular killing by resident peritoneal macrophages from salmonella-resistant CBA and salmonella-susceptible C57BL/10 mice

The aim of the present study was to determine whether the difference between the rate of intracellular killing of Salmonella typhimurium by macrophages of salmonella-resistant CBA and salmonella-susceptible C57BL/10 mice also holds for other salmonellae and other bacteria species. After in vivo phagocytosis, the initial rate of in vitro intracellular killing of S. typhimurium phagetype 505, S. typhimurium phagetype 510, and S. typhimurium M206 by macrophages of CBA mice amounted always to approximately 1.7 times the value found for macrophages of C57BL/10 mice (p less than 0.001), indicating that the difference in killing efficiency between CBA and C57BL/10 macrophages holds for various strains of S. typhimurium. However, some other salmonella species, i.e., S. dublin and S. heidelberg, as well as E. coli 054 and 02K1+, Listeria monocytogenes EGD and L347, and Staphylococcus aureus were killed equally efficiently by macrophages of both mouse strains. These findings indicate that the difference between the rates of intracellular killing by macrophages of salmonella-resistant CBA and salmonella-susceptible C57BL/10 does not hold for several other bacteria species and thus might be specific for S. typhimurium. Subsequent experiments showed that the in vivo proliferation of S. typhimurium 510 in the first 2 days after i.v. injection was 2.0-fold to 3.0-fold higher in the spleens and livers of C57BL/10 mice than in those of CBA mice, whereas the in vivo proliferation of S. dublin and S. heidelberg was between 1.0-fold to 1.4-fold higher in the C57BL/10 mice. These findings suggest that the differences between the rate of in vitro intracellular killing of salmonella by CBA and C57BL/10 macrophages are reflected in differences in the rate of in vivo proliferation of these microorganisms in CBA and C57BL/10 mice. To gain insight into the involvement of the oxidative metabolism of CBA and C57BL/10 macrophages in the difference in the rate of intracellular killing of S. typhimurium, the O2 consumption and H2O2 release by resident peritoneal macrophages was determined. The amplitudes of the respiratory burst and the release of H2O2 was identical in macrophages of the two mouse strains after triggering by either preopsonized heat-killed S. typhimurium or phorbol myristic acetate. These findings indicate that the mouse species-associated difference in the intracellular killing of S. typhimurium is not caused by a difference in the oxidative metabolism of CBA and C57BL/10 macrophages.     

Growth-related changes of oxygen consumption rates of tumor cells grown in vitro and in vivo

Growth-related changes of oxygen consumption rates of tumor cells, grown in vitro or in vivo, were investigated. For in vitro investigations, L929 and DS-carcinosarcoma cells were cultured in artificial media. For in vivo studies, DS-carcinosarcoma cells were implanted into the abdominal cavity of Sprague-Dawley rats (ascites tumor, containing malignant cells, leukocytes, lymphocytes, and macrophages). Oxygen uptake was measured photometrically. Parameters of the extracellular medium judged to possibly influence the respiratory activity of tumor cells were monitored at different growth stages (glucose, lactate, and amino acid levels, oxygen and carbon dioxide partial pressures, and pH values). The results obtained clearly show that the oxygen uptake of tumor cells grown in vitro decreased as quiescence developed. In contrast, the respiratory activity of in vivo DS-carcinosarcoma ascites cells increased as tumor growth reached plateau phase. The differences observed cannot be attributed solely to changes of the environmental conditions monitored. It is likely that an increased respiration rate of activated host cells might profoundly contribute to the elevation of the respiratory capacity of DS-carcinosarcoma ascites tumors grown in vivo. These data provide evidence that solid tumors in vivo can increase their O2 uptake at an enhanced O2 availability not only due to an enlarged tumor volume with adequate O2 supply but also due to an elevation of the respiratory activity of different cell populations within a tumor.     

Changes in pulmonary gas exchange during resistive loading that do not cause a sense of shortness of breath

It is known that hypoxic hypometabolism occurs as a result of reduced delivery of oxygen to tissues. We have shown earlier that this response may be observed during latent hypoxia, when blood oxygen saturation (SpO₂) is reduced to 95%. There is a hypothesis that the body can prevent a disturbance of the balance between oxygen delivery and consumption by developing a protective response to reduce oxygen demand. To test the hypothesis, a study was carried out under normal oxygenation conditions, in which a weak additional resistance of 0.4 cm H₂O L^?1 s was used as a trigger. The study sample comprised 14 healthy subjects of both sexes. Gas exchange parameters under normal and combined resistive loading conditions were studied. It was found that the respiratory rate was reduced by 8%, and the tidal volume was increased by 12%. At the same time, oxygen consumption and carbon dioxide production were significantly decreased by 9 and 10%, respectively. These findings suggest that a decrease in the rates of oxygen consumption and carbon dioxide production is a nonspecific protective response to prevent the disturbance of the balance between oxygen delivery and consumption.     

Macrophages as a major source of oxygen radicals in the hyperoxic newborn rat lung

The lungs of newborn rats exposed to 60% O(2) for 14 d were found to have a greatly increased cyanide-insensitive O(2) consumption, reflecting increased reactive oxygen species (ROS) formation. Exposure of the lung to hyperoxia is known to increase the production of ROS by mitochondria. We hypothesized that macrophages may also be a major contributor to this increase. Newborn rat pups were exposed to either air or 60% O(2) for 14 d and received either intraperitoneal gadolinium chloride (GdCl(3)) to abrogate macrophage influx, or inert vehicle. Lung homogenates were equilibrated in either 21% or 100% O(2) and total and cyanide-insensitive O(2) consumption, as well as nitric oxide accumulation were measured polarographically. Citrate synthase, a marker of mitochondrial mass, and nitrotyrosine, a marker of peroxynitrite formation, were quantified by Western blot. In addition to increased macrophage numbers, the lungs of 60% O(2)-exposed animals had greatly increased cyanide-insensitive O(2) consumption (p <.05 compared to air controls) and immunoreactive nitrotyrosine (p <.05), which were all completely abrogated by treatment with GdCl(3). Exposure to 60% O(2) for 14 d had no effect on peroxynitrite-independent nitric oxide release or mitochondrial mass. We conclude that increased ROS in the lungs of newborn rats exposed to 60% O(2) for 14 d was likely to be caused, in significant part, by the presence of increased numbers of macrophages.     

Adsorption of lipoproteins onto mineral dust surfaces: a possible factor in the pathogenesis of particle-induced pulmonary fibrosis?

We compare the adsorption behavior of high density lipoproteins (HDL) and low density lipoproteins (LDL) on "fibrogenic" and "nonfibrogenic" mineral dusts. The adsorption tests with bovine lipoprotein concentrate and human serum produced the following results: 1) All seven examined fibrogenic dusts (SiO2 DQ12, SiO2 F600, silica, graphite, TiC, kaolin, talc) adsorbed significantly more high density lipoproteins (HDL), than the five examined nonfibrogenic (inert) dusts (TiO2, SnO2, Al2O3, Fe2O3, Fe3O4). This different behavior was particularly conspicuous in the presence of competing adsorbates (serum proteins). 2) In contrast, the adsorption of LDL did not correlate with the fibrogenicity of the mineral dusts. 3) The known silicosis-protective substance polyvinylpyridine-N-oxide inhibits the HDL adsorption of alpha-quartz. These results indicate that the adsorption of HDL could have a causal relationship with the triggering of a fibrotic reaction. The adsorption on the surface of fibrogenic dust particles provides an exceptional opportunity for the intake of HDL by macrophages. During the phagocytosis of the inhaled dust particles, the HDL adsorbed on the surface of the particles could be taken up by macrophages regardless of the receptor. There the HDL particles and/or compounds associated with them, such as lecithin-cholesterol-acyltransferase, could stimulate the macrophages to release fibrogenic mediators by some yet unknown mechanism.     

Effects of ambient air particles on nitric oxide production in macrophage cell lines

We assessed the in vitro toxicity of various particles on three murine macrophage cell lines, (J774A.1, WR19M.1, RAW264.7). The cells were exposed to aqueous suspensions (0-100 microg/30 mm2 well) of urban particulate matter (SRM-1648, SRM-1649, EHC-93), fine particulate matter (PM2.5), titanium dioxide (SRM-154b), and respirable cristobalite (SRM-1879) for 2 h and were then stimulated with lipopolysaccharide (LPS, 100 ng/ml) and recombinant interferon-gamma (IFN, 100 U/ml). After overnight incubation with the particles and LPS/IFN, nitric oxide production was estimated from culture supernatant nitrite. Cell viability was determined by monitoring the rate of AlamarBlue reduction. The dose-effect relationships for nitrite and viability were modeled as a power function (Fold change = [Dose+1]beta), where beta represents the slope of the dose-response curve. Potency was defined as the rate of change in nitrite production corrected for cell viability (beta(POTENCY) = beta(NITRITE) - beta(VIABILITY)). Overall, the urban particles decreased nitric oxide production (beta(POTENCY) < 0), while exposure of the cells to fine particulate matter or cristobalite increased the production of nitric oxide (beta(POTENCY) > 0). Titanium dioxide (TiO2) was essentially inactive (beta(POTENCY) approximately to 0). The decrease in nitric oxide production seen in cells exposed to the urban particles was directly correlated to a decrease in the expression of inducible nitric oxide (iNOS) as determined by Western blot analysis. The results indicate that particles are modulators of nitric oxide production in murine macrophages and may directly disrupt expression of iNOS during concomitant pathogen exposure. Pathways leading to enhanced NO production causing cell injury, and to decreased NO release resulting in lower bacterial clearance, may both be relevant to the health effects of ambient particles.     

Gas Exchange of Algae: IV. Reliability of Chlorella pyrenoidosa

A single culture of Chlorella pyrenoidosa (700 ml) was grown continuously under uniform environmental conditions for a period of 11 months. During this time, the culture remained uncontaminated and its oxygen production, carbon dioxide consumption, and photosynthetic quotient (PQ = CO(2)/O(2)) were monitored on a 24-hr basis. The gas exchange characteristics of the alga were found to be extremely reliable; the average oxygen production was 1.21 +/- 0.03 ml per min, the carbon dioxide consumption was 1.09 +/- 0.03 ml per min, and the PQ was 0.90 +/- 0.01 when changes in both lamp intensity and instrument accuracy were taken into consideration. Such long-term dependability in the production of oxygen, consumption of carbon dioxide, and maintenance of a uniform PQ warrants the use of C. pyrenoidosa in a regenerative life support system for space travel.     

Metabolic consequences of reduced frequency breathing during submaximal exercise at moderate altitude

The intention of this study was to determine the metabolic consequences of reduced frequency breathing (RFB) at total lung capacity (TLC) in competitive cyclists during submaximal exercise at moderate altitude (1520 m; barometric pressure, PB = 84.6 kPa; 635 mm Hg). Nine trained males performed an RFB exercise test (10 breaths.min-1) and a normal breathing exercise test at 75-85% of the ventilatory threshold intensity for 6 min on separate days. RFB exercise induced significant (P less than 0.05) decreases in ventilation (VE), carbon dioxide production (VCO2), respiratory exchange ratio (RER), ventilatory equivalent for O2 consumption (VE/VO2), arterial O2 saturation and increases in heart rate and venous lactate concentration, while maintaining a similar O2 consumption (VO2). During recovery from RFB exercise (spontaneous breathing) a significant (P less than 0.05) decreases in blood pH was detected along with increases in VE, VO2, VCO2, RER, and venous partial pressure of carbon dioxide. The results indicate that voluntary hypoventilation at TLC, during submaximal cycling exercise at moderate altitude, elicits systemic hypercapnia, arterial hypoxemia, tissue hypoxia and acidosis. These data suggest that RFB exercise at moderate altitude causes an increase in energy production from glycolytic pathways above that which occurs with normal breathing.