SOURCES OF ERROR AND THE NO-PREFERENCE OPTION IN DAIRY PRODUCT TESTING

When products are physically identical, consumers will choose a no‐preference option in a paired preference test only about 30% of the time, giving a nonintuitive result. We evaluated the no‐preference false alarm rate in dairy products and the potential sources of error in panelist behavior, including discrimination problems and poor repeatability of judgments. Paired preference tests were conducted with milk (2% versus nonfat or skim), with cottage cheese (4% versus nonfat) and with identical samples. Triangle, dual standard and same/different discrimination tests were also conducted. The no‐preference option was chosen by about 30% of the consumers when samples were identical, and less frequently when samples were different. Discrimination performance, although statistically significant, was poorer than expected with about 30% discriminators (d′ of 1.7) in most tests. Even in the dual standard tests on milk (visually obvious and with references present), performance was only 88% correct (76% discriminators). Repeatability in preference tests was also poorer than expected, with only 56% choosing the same preference option for different samples on repeat trials although the group preferences were stable. Same/different tests indicated that over 50% of the consumers called identical samples different, although this fell short of explaining the 70% average false alarm rate in preferences. Even with apparently discriminable consumer products, accurate discrimination of the samples and repeatability of preferences should not be assumed. Random responding may contribute to error variance and produce nonsensical results such as the expression of choice between identical samples.     

In vivo detection of rabbit atropinesterase

The comparability of an in vivo rapid screening test for the presence of atropinesterase with an in vitro standard colorimetric test was assessed using 410 male and female New Zealand white rabbits. The results from both tests were in agreement in 405 of the 410 (98.8%) rabbits compared. One false negative and four false positive results occurred with the rapid screening test.     

BIOCHEMICAL AND MICROCHEMICAL STUDY OF THE CELL WALLS OF RHIZIDIOMYCES SP.

Fuller , Melvin S. (Brown U., Providence, R. I.) Biochemical and microchemical study of the cell walls of Rhizidiomyces sp. Amer. Jour. Bot. 47(10): 838–842. lllus. 1960.—The presence of chitin in the cell walls of the fungus Rhizidiomyces is demonstrated by qualitative analysis of enzymatic and hydrochloric-acid hydrolysates of partially cleaned cell walls. Qualitative examination of the enzymatic and acid hydrolysates did not, however, serve for the detection of cellulose present in the cell walls of Rhizidiomyces. With microchemical tests, both chitin and cellulose can be detected. These microchemical tests served to indicate the localization of the chitin and cellulose in the cell walls of mature plants before and during zoospore discharge.     

THE PENETRATION OF THE MEMBRANE OF BRAIN MITOCHONDRIA BY ANIONS

The permeability of the membrane of rat brain non-synaptosomal mitochondria, towards inorganic and substrate anions, was assessed by measuring the rate of swelling that occurred when mitochondria were suspended in an iso-osmotic solution of a permeant anion, in the presence of a permeant cation such as NH⁺₄ or K⁺ in the presence or absence of valinomycin. In NH⁺₄-phosphate swelling was higher than it was in KCI or K⁺-phosphate, which showed the prevalence of the mechanism of phosphate transport previously demonstrated in liver mitochondria. The entry of succinate and L-malate seemed to require the presence in the inner mitochondrial membrane of specific carriers. as previously postulated for liver mitochondria, but the rate of swelling of brain mitochondria was lower than that of liver organelles. In K⁺-succinate, in the presence of antimycin, added ATP induced swelling and this was attributable to the simultaneous permeation both of the anion and the cation. Fumarate did not penetrate into brain mitochondria. Practically no swelling was recorded in NH⁺₄ or K⁺-citrate, which indicated that this anion penetrated poorly into the isolated brain mitochondria even in the presence of malate. Swelling occurred in NH⁺₄-L-glutamate in the presence of rotenone, and the entry of this anion seemed to follow a gradient of concentration although the presence of a specific translocator in the inner mitochondrial membrane might be concerned. The entry of glutamate was independent of that of phosphate and N-ethylmaleimide appeared to be a specific inhibitor of this entry. Swelling in K⁺-L-glutamate, in the presence of rotenone, was enhanced by the addition of valinomycin or ATP but in the latter case when osmotic equilibrium was reached swelling was not reversed by oligomycin. In conclusion, the lesser extent of swelling of isolated brain mitochondria compared with liver mitochondria could be attributed to the heterogeneity of the populations of these organelles, each population possessing its own characteristics of membrane permeability. Observations of electron micrographs of brain mitochondria incubated in iso-osmotic substrate anions confirmed the heterogeneous rate of swelling of these particles.     

THE USE OF GLUCOSE INORGANIC SALTS MEDIA IN THE CLASSIFICATION OF THE COLI-AEROGENES BACTERIA. I. THE METHYL RED AND VOGES-PROSKAUER REACTIONS

SUMMARY: A chemically defined glucose ammonium phosphate medium gave methy red and Voges-Proskauer reactions which were superior to those in glucose peptone phosphate. Optimum condition for both tests require a starting pH of 6·8 and incubation for 3 days at 30°. The medium gave a negative correlation between the two reactions with 34 out of 35 strains that were positive to both tests in the peptone medium. The addition of glutamic acid helped to eliminate doubtful positive M. R. reactions but seemed to suppress acetylmethylcarbinol production by weakly V.-P. positive strains.     

CLEARANCE OF THE POLYAMINES FROM THE PERFUSED CEREBROVENTRICULAR SYSTEM OF THE RABBIT

Abstract— The clearance of the polyamines spermidine and spermine from cerebrospinal fluid was investigated in the rabbit by ventriculocisternal perfusion. Clearance involved both saturable and nonsaturable uptake processes. The saturable component was a high affinity system with an affinity constant of 21 μ m for spermidine and 24 μ m for spermine. The clearance of spermidine was reduced by the presence of spermine and vice-versa. Other polyamine congeners also reduced spermidine and spermine clearance and it is suggested that the two polyamines share the same carrier. Evidence for concentrative uptake of polyamines into choroid plexus is presented and it is suggested that an active system may also transport polyamines into brain tissue. At high perfusion concentrations simple diffusion may also take place.     

THE PRODUCTION OF VOLATILE FATTY ACIDS BY BACTERIA OF THE DYSENTERY GROUP

These studies show: 1. A close agreement exists among all the organisms studied in the total quantity of volatile fatty acids produced and in the ratio of formic to acetic, under aerobic conditions, and in the presence of 1 per cent of glucose. 2. When grown upon peptone alone, with free access of air to the cultures, volatile fatty acids are produced in appreciable quantities, although the reaction of the solution has gone more alkaline as shown by colorimetric pH tests. Formic acid is not found, but in its place we obtain propionic acid. 3. Upon exhaustion of air from the non-sugar medium the bacteria again produce formic acid, and in addition some butyric. This is true for both Shiga and non-Shiga cultures. The reaction is distinctly more acid. 4. The presence of glucose in the medium from which the air has been pumped furnishes a condition which provokes about the same type and degree of fermentation that operates in the glucose medium bathed in air at atmospheric pressure. 5. The enormous quantity of formic acid produced by these bacteria may play a significant part in the digestive disturbances and toxic symptoms accompanying their infection of the human intestinal tract.     

THE EFFECTIVENESS OF COMMON FOODS FOR REDUCTION OF CAPSAICIN BURN1

Capsaicin burn was induced by a one percent solution of Tabasco ^TM sauce in spring water. Four foods, rice, water, butter, and pineapple juice, warmed to 35°C, were used to reduce the burn. A no food treatment was used as a control. Subjects recorded perceived burn intensity by placing slash marks on line scales at set time intervals throughout the tests. Burn was significantly reduced while the foods were in the mouth but increased after the foods were expectorated. The decreased burn may be due to the very presence of a food in the mouth.     

THE LOCALIZATION OF ENZYME ACTIVITIES IN THE RAT BRAIN

Studies with rat brain illustrate the usefulness of formol-calcium-fixed tissue for studying both enzymatic "chemoarchitectonics" and intracellular organelles. Unembedded frozen sections and polyvinyl alcohol-embedded sections may be used to demonstrate the activities of DPNH-tetrazolium reductase localized in mitochondria and ergastoplasm, TPNH-tetrazolium reductase localized in mitochondria, ATPase (and/or apyrase or ADPase) in cell membranes, and acid phosphatase in lysosomes.¹ Among the observations recorded are: (1) the presence of lysosomes in all cells of the brain; (2) the presence of numerous large lysosomes near the nuclei of capillary endothelial cells; (3) a polarized arrangement of large lysosomes in epithelial cells of the ependyma and choroid plexus; (4) the presence of ATPase activity in the cell membranes of some neurons; (5) the presence of either an apyrase or combination of ATPase and ADPase in the cell membranes of neuroglia and capillaries; (6) the presence of both DPNH- and TPNH-tetrazolium reductase activities in neuroglia; (7) the presence of DPNH- and TPNH-tetrazolium reductase activities in mitochondria and of DPNH-tetrazolium reductase activity in Nissl substance. The possible functional significance of these localizations is briefly discussed, as is their relation to "quantitative histochemistry" data available in the literature.     

THE RATES OF GROWTH OF SOME THERMODURIC BACTERIA IN PURE CULTURE AND THEIR EFFECTS ON TESTS FOR THE KEEPING QUALITY OF MILK

SUMMARY: The growth rates of eleven representative thermoduric bacteria, comprising 3 aerobic spore formers, 3 streptococci, 1 Corynebacterium lacticum and 4 micrococci, have been determined in glucose broth and sterile pasteurized milk at 37·5°, 26° and 15°. The spore formers and streptococci were generally not affected by the presence of inhibitory factors in pasteurized milk. When multiplication of micrococci and C. lacticum occurred in milk this was only after a lag period. One micrococcus showed an unusual series of growth phases in glucose broth at 37·5°, possibly due to the appearance of mutants or to adaptation of the organism to growth at that temperature. This was not observed in pasteurized milk. C. lacticum died off when incubated in glucose broth at 37·5°.
None of the keeping quality tests was more effective than any other in detecting these organisms in milk. The micrococci and C. lacticum had little effect on the keeping quality of pasteurized milk within the period of 'commercial life'. Some of the spore formers and streptococci showed marked differences in the end-points with the clot-on-boiling and the alcohol precipitation tests.     

STRUCTURE AND FUNCTION OF THE ALGAL PYRENOID. I. ULTRASTRUCTURE AND CYTOCHEMISTRY DURING ZOOSPOROGENESIS OF TETRACYSTIS EXCENTRICA1

The fine structure of the pyrenoid in the mature vegetative cell of Tetracystis excentrica Brown and Bold is described. During zoosporogenesis, the pyrenoid undergoes regression, and the ultrastructure of this process is described in detail. The ground substance undergoes dissolution, and reticulate fibrillar structures appear as well as intruding chloroplast thylakoids. Pyrenoid-associated starch plates diminish, and quantities of starch not associated with the pyrenoid are produced. New pyrenoids appear late in the division cycle after all other major organelles associated with the motile cell have been formed. Zoospore pyrenoids develop in thylakoid-free spaces of the chloroplast which are similar to the DNA-containing regions. The new pyrenoid ground substance, which is loosely fibrillar, arises in close proximity to starch grains which may be formed in the stroma. Then the zoospore pyrenoid produces 2 hemispherical starch plates identical to those in the mature vegetative cell. Zoospore pyrenoids lack the 2 convoluted thylakoids between the starch plates and the ground substance characteristic of those in the mature vegetative cell. Instead, the thylakoids are identical to those of the chloroplast at first, and then develop into a convoluted state in the vegetative cell. Cytochemical tests for DNA, RNA, and protein were made for the cytoplasm, nucleus, nucleolus, and pyrenoid. Conclusive evidence is presented for the presence of RNA in the cytoplasm and nucleolus, DNA in the nucleus, and protein in the pyrenoid. The tests did not conclusively demonstrate the presence or absence of DNA and RNA in the pyrenoid; however, they suggested that small amounts of both DNA and RNA may be present.     

Evaluation of five hepatitis C virus screening tests and two supplemental assays: performance when testing sera from sexually transmitted diseases clinic attendees in the USA

The performances of five screening tests (recombinant peptide-based first and second generation tests from Abbott and Ortho, and a synthetic peptide-based test from Biochem Immunosystems) and two supplemental tests: recombinant peptide- based, Abbott neutralization test and Chiron second generation recombinant immunoblot assay (RIBA 2), were evaluated for their ability to detect hepatitis C virus (HCV) antibodies in a population of 276 individuals attending a sexually transmitted diseases (STD) clinic in the USA. Although the five screening tests produced a variable number (35-62) of repeatedly reactive samples, only 13% (36/276) were classified as true positives by the supplemental tests. Thirty-four of the 36 were reactive by all screening tests and 32 of the true positives were reactive by both supplemental tests, while 2 did not neutralize but were reactive in the RIBA 2 test. Of the remaining 2 of the true positives which were discordant by several of the screening assays, 1 was confirmed by both supplemental assays but the other required a chemiluminescent enhancement technique to show positivity in RIBA 2. The sensitivities of the first and second generation Abbott and Ortho tests ranged from 97% to 100% and that of the Biochem test was 94%. The specificities of these tests ranged from 89.2% to 99.6%. The second generation Ortho test presented 9.4% (26/276) false positives. The use of second generation Ortho as a screening test would lead to an excessive number of confirmatory false positives. the positive predictive values of the screening tests ranged from 58.1% to 97.1%. Although the synthetic peptide based Biochem test exhibited the best overall indices, the presence of 2 false negative results would prevent its use as a singular screening test. Nevertheless its high specificity may lend itself to be used as a second screening test before confirmatory testing with RIBA 2.     

我国沿海拟虎鲸骨骼研究

本文对我国沿海所捕获的拟虎鲸骨骼系统,进行了较全面的研究和测量,并对其骨骼特点及形态、功能方面也做了些探讨。     

THE EFFECT OF OPTIC TENTACLE REMOVAL ON THE TRANSMITTER CONTENT OF THE GIANT SEROTONIN CELL OF HELIX ASPERSA

Abstract— There is a giant serotonin-containing neuron in each metacerebral ganglion of the snail Helix pumntia. Much of the amine is localized in small granular vesicles (COTTRELL and OBSORNE, 1970) and evidence for serotonin having a transmitter role in each giant neuron is very strong (COTTRBLL, 1970a, b). It is shown that the content of serotonin in each giant neuron is reduced by ablation of the optic tentacle. Maximum depletion of amine (about 70 per cent) was observed at 6–8 days after the operation. Unilateral depletion followed removal of only one tentacle. To examine the observations more closely, electrophysiological experiments were also made to determine any neuronal connection between the tentacles and the serotonin-containing neurons. No evidence was found for the presence of an axon from either giant neuron in the nerves leading to the tentacles. Stimulation of the nerves supplying the tentacles caused both depolarization and spike firing, and hyperpolarization and inhibition of the giant neurons. It is possible that the depletion of serotonin following ablation of the optic tentacles results from an interruption of the nerve fibres mediating in one or both of the observed types of input.     

八株芽孢杆菌菌株的分类及固氮活性的测定

从8个省市的不同土壤分离了200个菌株,筛选出8株（JR₁,JR₂,JR₅,ZZ₃,ZZ₁₂,ZZ₁₆,M₁,K₄）能在无氮培养基上生长良好的典型的芽抱杆菌,其中6株（JR₁,JR₂,JR₄和ZZ₃,ZZ₁₂,ZZ     

Diffprot - software for non-parametric statistical analysis of differential proteomics data

Mass spectrometry-based global proteomics experiments generate large sets of data that can be converted into useful information only with an appropriate statistical approach. We present Diffprot - a software tool for statistical analysis of MS-derived quantitative data. With implemented resampling-based statistical test and local variance estimate, Diffprot allows to draw significant results from small scale experiments and effectively eliminates false positive results. To demonstrate the advantages of this software, we performed two spike-in tests with complex biological matrices, one label-free and one based on iTRAQ quantification; in addition, we performed an iTRAQ experiment on bacterial samples. In the spike-in tests, protein ratios were estimated and were in good agreement with theoretical values; statistical significance was assigned to spiked proteins and single or no false positive results were obtained with Diffprot. We compared the performance of Diffprot with other statistical tests - widely used t-test and non-parametric Wilcoxon test. In contrast to Diffprot, both generated many false positive hits in the spike-in experiment. This proved the superiority of the resampling-based method in terms of specificity, making Diffprot a rational choice for small scale high-throughput experiments, when the need to control the false positive rate is particularly pressing.     

MULTIPLE LABORATORY EVALUATION OF THE REITER PROTEIN COMPLEMENT FIXATION METHOD

Duplicate Reiter protein complement fixation tests were carried out on different days at the UCLA laboratory on 636 specimens entailing diagnostic problems. Results were in agreement in 94.2 per cent of cases.A comparison of the results obtained with the first RPCF test carried out on 639 diagnostic problem specimens submitted to four Los Angeles laboratories showed disagreement ranging from 10 to 13 per cent.Agreement between RPCF and TPI results in each of the four laboratories ranged from 81.2 to 82.7 per cent.A greater correlation was obtained between RPCF and TPI results than between TPI and STS or RPCF and STS.In the presence of nonreactive RPCF tests, from 5.6 to 7.1 per cent of the specimens tested in each laboratory were reactive to VDRL and TPI tests. Nonreactive VDRL and reactive TPI results ranged from 7.2 to 8.3 per cent of the specimens tested.In the presence of reactive TPI and RPCF results, 5.5 to 6.4 per cent of the specimens tested in each laboratory showed nonreactive VDRL tests.Twenty-nine or 4.6 per cent of 625 specimens tested showed nonreactive VDRL, reactive cardiolipin Kolmer and reactive TPI tests.Of the weakly reactive RPCF, VDRL or cardiolipin Kolmer tests, a higher percentage of the RPCF results gave reactive TPI tests than did either the VDRL or cardiolipin Kolmer procedures.The number of specimens showing discrepant RPCF results upon being retested in the four laboratories ranged from 33 to 68. Reactive TPI tests on those specimens ranged from 30.3 per cent to 54.4 per cent.     

A STUDY OF THE EFFECT OF MILDEW INFECTION ON THE REACTION OF WHEAT VARIETIES TO BROWN RUST

The effect of the presence of Erysiphe graminis tritici on the reactions of each of five wheats, Malakoff, Democrat, Mediterranean, Hussar and Webster, to Puccinia triticina was studied. Under normal environmental conditions, mildew increased the susceptibility to rust of Malakoff and Democrat, though not, except in isolated instances, that of Mediterranean or Hussar. High light intensities enhanced the effect of mildew on the reaction of Democrat to P. triticina. The susceptibility of Webster to rust was unaffected or decreased by the presence of mildew.
In all varieties there was a decided tendency for rust and mildew to develop on different parts of the leaf, and when a leaf was heavily mildewed the development of P. triticina was sometimes almost entirely inhibited. The reason for this is obscure, since spores of P. triticina and E. g. tritici germinate well in each others presence, and cytological studies revealed several cases of the presence of both mildew and rust haustoria in a single living host cell. Anatomical investigations also showed that the effect of mildew on rust infection was confined to rust pustules within 1 mm. of mildew colonies.
The results obtained are in accordance with Gassner's theory that susceptibility to rust is due to the presence of certain specific proteins in the host leaf.     

THE MICROBIOLOGICAL EXAMINATION OF BUTTER

SUMMARY: Butter made on farms and at creameries was examined microbiologically within 24 hr of production. The overall care exercised in the manufacture of the butter was reflected in the results obtained with the various tests used. Colony counts of psychrophiles, coli-aerogenes organisms, and yeasts and moulds were the most useful and economical tests for providing information on the standard of hygiene during manufacture, and they gave some indication of the potential keeping quality of the butter. The following satisfactory levels are recommended for creamery butter: psychrophiles <10³/g, coli-aerogenes organisms <10/g and yeasts and moulds <50/g.     

A SIMPLIFIED METHOD FOR THE URINARY EXCRETION TEST OF ABSORPTION OF COBALT 60 LABELLED VITAMIN B12

It is possible to do both radioiodine uptake studies and urinary excretion tests for absorption of Cobalt 60 vitamin B₁₂ with the same basic equipment. If a spectrometer is used and the samples properly prepared, the latter procedure can be performed quickly, accurately and with a minimum of laboratory equipment. This is a distinct advantage to a small laboratory with limited facilities, and should help to make both of these useful tests available for clinical use.