Sensometric calibration of sensory characteristics of commercially available milk products with instrumental data.

Seven brands of commercial milk and related products that are available in the Japanese market were investigated. Quantitative descriptive analysis was used to describe 12 sensory properties of the samples, and the position of each sample was displayed by principal component analysis. The sensory descriptors of the samples were correlated with various analytical data by partial least squares regression analysis. Aroma descriptors were correlated with the headspace gas chromatography-mass spectrometry profile. Descriptors of flavor, mouthfeel, and aftertaste were correlated with the results of the physicochemical analysis. Many of the volatile compounds that contributed to aroma attributes, according to the partial least squares loading plot, were in agreement with the influence of volatile compounds shown by previous studies. Lactulose and furosine, as indicators of heating, and viscosity were parameters that influenced flavor, mouthfeel, and aftertaste. In addition, overall aftertaste was significantly related to fat content.

Influence of whipping temperature on the whipping properties and rheological characteristics of whipped cream.

The effects of whipping temperature (5 to 15 degrees C) on the whipping (whipping time and overrun) and rheological properties of whipped cream were studied. Fat globule aggregation (aggregation ratio of fat globules and serum viscosity) and air bubble factors (overrun, diameter, and surface area) were measured to investigate the mechanism of whipping. Whipping time, overrun, and bubble diameters decreased with increasing temperature, with the exception of bubble size at 15 degrees C. The aggregation ratio of fat globules tended to increase with increasing temperature. Changes in hardness and bubble size during storage were relatively small at higher temperatures (12.5 and 15 degrees C). Changes in overrun during storage were relatively small in the middle temperature range (7.5 to 12.5 degrees C). From the results, the temperature range of 7.5 to 12.5 degrees C is recommended for making whipped creams with a good texture, and a specific temperature should be decided when taking into account the preferred overrun. The correlation between the whipped cream strain hardness and serum viscosity was high (R(2)=0.906) and persisted throughout the temperature range tested (5 to 15 degrees C). A similar result was obtained at a different whipping speed (140 rpm). The multiple regression analysis in the range of 5 to 12.5 degrees C indicated a high correlation (R(2)=0.946) in which a dependent variable was the storage modulus of whipped cream and independent variables were bubble surface area and serum viscosity. Therefore, fat aggregation and air bubble properties are important factors in the development of cream hardness. The results of this study suggest that whipping temperature influences fat globule aggregation and the properties of air bubbles in whipped cream, which alters its rheological properties.

Inhibition by amines indicates involvement of nitrogen dioxide in autocatalytic oxidation of oxyhemoglobin by nitrite.

Oxidation of oxyhemoglobin by nitrite is characterized by a lag period followed by an autocatalytic phase. The oxidation can be inhibited by the addition of morpholine, piperidine, triethanolamine or triethylamine (6 mM each). These amines are known to react with nitrogen dioxide to yield nitrosamine. Unexpectedly, aniline or aminopyrine (120 microM each) markedly inhibited the oxidation. These compounds, but not the other amines given above, inhibited the peroxide compound formation from methemoglobin and hydrogen peroxide. The results establish that, during the oxidation, the peroxide compound is generated and converts nitrite into nitrogen dioxide by its peroxidatic activity, resulting in an autocatalytic phase.

Discrimination of consonance and dissonance in Java sparrows.

Six adult Java sparrows were trained to discriminate between consonant and dissonant sounds consisting of three tones. In the consonance group, the perching response was reinforced when consonance was presented, but not when dissonance was presented. Both groups were given an inversion test, in which the first inversion of the chord was used as a stimulus. Four of six birds learned the discrimination and were given two tests. In the first test, novel consonances and novel dissonances were presented. All birds maintained the discrimination. When inverted consonances and dissonances were presented in the second test, the discriminative behavior was not well demonstrated. When novel dissonances consisting of tones with different intervals were presented in the third test, birds trained to perch for dissonance performed well, whereas those trained to perch for consonance did not. In summary, Java sparrows were able to discriminate between consonances and dissonances and demonstrated generalization to new combinations, they do not discriminate the same consonances and dissonances.

The interaction between nitrogen oxides and hemoglobin and endothelium-derived relaxing factor.

Among nitrogen oxides, NO and NO2 are free radicals and show a variety of biological effects. NO2 is a strongly oxidizing toxicant, although NO, not oxidizing as NO2, is toxic in that it interacts with hemoglobin to form nitrosyl- and methemoglobin. Nitrosylhemoglobin shows a characteristic electron spin resonance (ESR) signal due to an odd electron localized on the nitrogen atom of NO and reacts with oxygen to yield nitrate and methemoglobin, which is rapidly reduced by methemoglobin reductase in red cells. NO was found to inhibit the reductase activity. Part of NO inhaled in the body is oxidized by oxygen to NO2, which easily dissolves in water and converts to nitrite and nitrate. The nitrite oxidizes oxyhemoglobin autocatalytically after a lag. The mechanism of the oxidation, particularly the involvement of superoxide, was controversial. The stoichiometry of the reaction has now been established using nitrate ion electrode and a methemoglobin free radical was detected by ESR during the oxidation. Complete inhibition of the autocatalysis by aniline or aminopyrine suggests that the radical catalyzes conversion of nitrite to NO2, which oxidizes oxyhemoglobin. Recently NO was shown to be one of endothelium-derived relaxing factors and the relaxation induced by the factor was inhibited by hemoglobin and potentiated by superoxide dismutase.

Proteinic prorenin-releasing-stimulator (PRS) in the rat submandibular gland.

The release of prorenin as well as renin from rat renal slices was confirmed by a rat prorenin-prosegment ELISA system and an assay system for determining the renin activity. A significant increase of the prorenin release was found by adding rat submandibular gland extract to the slice medium, indicating the existence of a prorenin-releasing stimulator (PRS) in the extract. The pI and molecular mass of PRS were 8.5-8.7 and 28-30 kDa, respectively. The PRS was completely inactivated by boiling or a proteinase treatment.

Induction of S100A4 gene expression inhibits in vitro invasiveness of human squamous cell carcinoma, KOSC-3 cells.

S100A4 is considered functionally involved in metastasis and invasiveness of rodent and human mammary tumors. We screened the expression of S100A4 in human squamous cell carcinoma cell lines, and found 2 cell lines which were highly invasive, but did not express any noticeable extent of S100A4. To examine whether the expression of S100A4 regulated invasiveness of squamous cell carcinoma, we transfected S100A4 cDNA into KOCS-3 and HSC-4 squamous cell carcinoma cells. The transfectants from KOSC-3 cells expressing sense S100A4 decreased invasiveness by 80% compared with cells of the wild type or those with the vector only.

Induction of SOS functions in Escherichia coli and biosynthesis of nitrosamine in rabbits by nitrogen dioxide.

Nitrogen dioxide induced SOS functions in Salmonella typhimurium and Escherichia coli K-12 and was mutagenic in Escherichia coli WP2. When a rabbit was administered aminopyrine intravenously and administered nitrogen dioxide by inhalation, N-nitrosodimethylamine was detected in its blood. Analysis was conducted with 15N-nitrosodimethylamine as an internal standard by a combination of capillary gas chromatography and mass spectrometry. Accompanying administration of cystamine increased the blood concentration of N-nitrosodimethylamine in the rabbit, suggesting inhibition of its metabolism. Concurrent sulfur trioxide inhalation increased N-nitrosodimethylamine formation in the rabbit.

Decrease of nitrate biosynthesis in scorbutic mutant rats unable to synthesize ascorbic acid.

The effect of ascorbic acid deficiency on the urinary excretion of nitrate was investigated using a mutant strain of rats (osteogenic disorder syndrome rats; ODS rats) unable to synthesize ascorbic acid. The amount of urinary nitrate excreted by ODS rats with or without ascorbic acid supplementation were measured before and after the intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS). Urinary nitrate excretion increased markedly after LPS injection. Urinary nitrate excretion by ODS rats not supplied with ascorbic acid was significantly less than that of those supplied with ascorbic acid both before and after LPS injection. These results show that ascorbic acid enhances both LPS-stimulated and constitutive nitrate production in vivo.

Induction of umuC gene expression by nitrogen dioxide in Salmonella typhimurium.

Gaseous nitrogen dioxide (NO2) was found to induce umuC gene expression in Salmonella typhimurium carrying the umuC-lacZ fusion plasmid. The induction level of the umu operon responsible for inducible mutagenesis was measured by the level of beta-galactosidase in the cell, encoded by the fusion gene. NO2 gas was bubbled into bacterial suspensions at 10, 30 and 90 microliters/l for 30 min at a flow rate of 100 ml/min. Expression of the umuC gene varied with the concentration, flow rate and bubbling time of the NO2 gas. Although NO2 gas induces SOS functions, mutagenesis due to it was not detectable in Salmonella typhimurium TA100 and TA102. Nitric oxide gas (NO) did not induce any umuC gene expression.

Induction of SOS functions by nitrogen dioxide in Escherichia coli with different DNA-repair capacities.

The effect of gaseous nitrogen dioxide (NO2) on cytotoxicity, induction of synthesis of UmuC and RecA proteins, and mutagenesis was studied in Escherichia coli strains with different capacities of DNA repair. Gaseous NO2 (90, 180 microliter/l) killed Escherichia coli. The recA mutant was most sensitive, the lexA mutant moderately sensitive, and the uvrA mutant and the wild-type the least sensitive. When 90 microliter/l NO2 gas was bubbled into bacterial suspensions for 30 min at a flow rate of 100 ml/min, the induction of umuC gene expression increased in the wild-type strain. NO2 also induced the recA gene expression in the wild-type strain. The synthesis of neither RecA nor UmuC proteins was induced in the recA and lexA mutants. We further investigated the NO2 mutagenesis in the cells treated with bubbling of NO2 gas. NO2 caused mutation to Trp+ of WP2.

Induction of sister-chromatid exchanges by N-nitrosocimetidine in cultured human lymphocytes and its inhibition by chemical compounds.

The effect of nitrosocimetidine (NC) on the frequency of sister-chromatid exchanges (SCEs) in human lymphocytes has been studied. The frequency of SCEs induced by a 1-h exposure to 2.6 X 10(-4) M NC was 4-fold greater than that in the solvent control. A 72-h exposure to NC had a similar dose-related effect. We also examined the effect of the sulfhydryl compounds cysteine, cysteamine, cystamine and glutathione, the reducing agent dithionite, and vitamins C and E on the NC-induced SCEs. None of these compounds induced SCEs. Cysteine, cysteamine, and cystamine significantly reduced the number of NC-induced SCEs, and the others did not.

Color analysis method for studying oxygen transport in hemoglobin solutions using an image-input and -processing system.

A method for quantitative analysis of hemoglobin color to estimate the oxygen saturation was developed. The method uses an image-input and -processing system composed of a 3-tube video camera and a digital image analyzer. Using the system connected to a microscope, facilitated diffusion of oxygen in hemoglobin solutions was observed and analyzed in a position-sensitive way. The results confirmed its applicability to this study and gave information about the diffusion mechanism expressed by the empirical formula J = kY, where J is the flux of oxygen, Y is the oxygen saturation of hemoglobin, and k is a constant.

Facilitated transport of oxygen through hemoglobin solutions.

A method for quantitative analysis of hemoglobin color to estimate the oxygen saturation was developed. The method uses an image-input and -processing system composed of a 3-tube video camera and a digital image analyzer. When the system is connected to a microscope, the facilitated diffusion of oxygen in hemoglobin solutions can be observed and analyzed in a position-sensitive manner. The results led to a new transport model expressed as: J = k'CY/d, where J is the oxygen flux, C is the hemoglobin concentration, Y is the oxygen saturation of hemoglobin, d is the distance between the entrance of oxygen and the diffusion front, and k' is a constant.

Measurement of nitrosodimethylamine by capillary gas chromatography-mass spectrometry with the 15N-labelled compound as an internal standard.

Artifactual formation of N-nitrosodimethylamine during the extraction procedure from aminopyrine and nitrite was examined. The use of the basic pH condition was the most effective in preventing artifactual formation. Sulfamic acid or ascorbic acid was partially effective in preventing artifactual formation. Since significant losses of volatile N-nitrosodimethylamine occur during the extraction and concentration steps, we analyzed N-nitrosodimethylamine by combined gas chromatography mass spectrometry with 15N-nitrosodimethylamine as an internal standard. The use of a fused silica capillary column enabled us to obtain a fine separation of the chromatogram. This methodology was applied to our model experiment, which was performed to locate the formation of N-nitrosodimethylamine when a rabbit was exposed to NO2 after the administration of aminopyrine. SO3 inhaled together with NO2 was found to increase the nitrosation.

A dynamic dialysis method for studying protein-ligand binding using chromatographic theory.

A new dynamic dialysis method has been developed for studying protein-ligand binding phenomena. The method depends on analysis of the elution pattern of ligand in a single dialyzing process where the ligand concentration in the sample compartment changes greatly with time. The dialyzer is composed of a long, narrow chamber (the sample compartment) between two sheets of semipermeable membrane and two outside chambers (the sink compartment) connected as a single path. Eluting buffer flows in the sink compartment to exchange the ligand with the solution in the sample compartment. Therefore, the ligand concentration gradient in the sink compartment is in the longitudinal direction. The mathematical expressions to analyze the experimental data were derived from a modified theory of chromatography. Examination of the binding of sulfanilamide to bovine serum albumin using this method shows that these equations are valid for use in studying protein-ligand binding.

Marked nitrosation by stimulation with lipopolysaccharide in ascorbic acid-deficient rats.

Marked formation of N-nitrosothioproline (N-nitrosothiazolidine-4-carboxylic acid) by stimulation with Escherichia coli lipopolysaccharide (LPS) was demonstrated in ascorbic acid-deficient mutant rats (osteogenic disorder syndrome rats; ODS rats) unable to synthesize ascorbic acid. The amounts of urinary nitrate and N-nitrosothioproline excretion after thioproline administration was measured in ODS rats with and without ascorbic acid supplement before and after the injection of LPS. LPS caused marked increase of urinary nitrate excretion in both groups. Urinary N-nitrosothioproline excretion increased 6-fold after LPS injection in ODS rats not supplied with ascorbic acid, but supplement with ascorbic acid markedly decreased the excretion of N-nitrosothioproline.