The effect of pH and nitrite concentration on the antimicrobial impact of celery juice concentrate compared with conventional sodium nitrite on Listeria monocytogenes.

The objectives of this study were to evaluate the impact of pH and nitrite from celery juice concentrate (CJ) on the growth of Listeria monocytogenes in broth and on ham slices, and to evaluate the impact of pH and nitrite from CJ on quality attributes of the ham. The pH of both broth and ham were increased by the addition of CJ. The CJ was less effective than conventional nitrite at 100 mg/kg nitrite in broth, but in ham, the CJ treatments at both 100 and 200 mg/kg resulted in growth of L. monocytogenes (p>0.05) similar to that of the conventional nitrite at the same concentrations. Reducing the pH of CJ before addition to the ham had greater impact on L. monocytogenes growth at 200 mg/kg nitrite than at 100 mg/kg. Celery juice concentrate may increase meat product pH which could have implications for the antimicrobial impact of nitrite in some products.

Dual skin tests with Mycobacterium avium sensitin and PPD to detect misdiagnosis of latent tuberculosis infection.

BACKGROUND: A positive tuberculin skin test (TST) may indicate cross-reacting immunity to non-tuberculous mycobacteria (NTM) and not latent tuberculosis infection (LTBI). OBJECTIVES: To assess misclassification of LTBI, as assessed by skin testing with Mycobacterium avium sensitin (MaS), and to determine how this misclassification affects the analysis of risk factors for LTBI. METHODS: In a population-based survey, participants underwent skin testing with M. tuberculosis purified protein derivative (PPD) and MaS. A PPD-dominant skin test was a reaction that was ≥ 3 mm larger than the MaS reaction; a MaS-dominant skin test was a reaction that was ≥ 3 mm larger than the PPD reaction. RESULTS: Of 447 randomly selected persons, 135 (30%) had a positive PPD test. Of these, 21 (16%) were MaS- dominant, and were therefore attributable to NTM and misclassified as LTBI. PPD reactions of 5-14 mm were more likely to be misclassified than those ≥ 15 mm (OR = 5.0, 95%CI 1.9-13.2). Adjusting for misclassification had only a small impact on the analysis of risk factors for LTBI. CONCLUSIONS: A substantial number of individuals who are diagnosed with LTBI are actually sensitized to NTM. Using dual skin testing would reduce misdiagnosis and prevent unnecessary treatment.

Combustion front dynamics in the combustion synthesis of refractory metal carbides and di-borides using time-resolved X-ray diffraction.

A compact diffraction-reaction chamber, using a 2-inch photodiode array detector, has been employed to investigate the chemical dynamics at the combustion front of a selected series of refractory metal carbides and di-borides from their constituent element reactants as well as binary products from B4C as a reactant. These systems are denoted as (i) M + C --> MC; (ii) M + 2B --> MB2; and (iii) 3M + B4C --> 2MB2 + MC, where M = Ti, Zr, Nb, Hf or Ta. Time-resolved X-ray diffraction using intense synchrotron radiation at frame rates up to 10 frames s(-1) (or 100 ms frame(-1)) was employed. The combustion reactions were found to complete within 200-400 ms. In contrast to the Ta + C --> TaC combustion system studied earlier, in which a discernible intermediate sub-carbide phase was first formed, reacted further and disappeared to yield the final TaC product, no intermediate sub-carbide or sub-boride was detected in the current systems. Combustion for the Ti, Zr and Hf systems involved a liquid phase, in which the adiabatic temperatures Tad are well above the melting points of the respective reactant metals and have a typical combustion front velocity of 5-6 mm s(-1). The Nb and Ta systems have lower Tad, involving no liquid phase. These are truly solid combustion systems and have a lower combustion front velocity of 1-2 mm s(-1). The current study opens up a new avenue to chemical dynamics and macrokinetic investigations of high-temperature solid-state reactions.

A new, simple, nonradioactive, nontoxic in vitro assay to monitor corneal endothelial cell viability.

PURPOSE: This study was designed to determine whether Alamar blue could be used to evaluate corneal endothelial cell viability in vitro. METHODS: Alamar blue incorporates a proprietary redox indicator that changes color in response to metabolic activity. Primary rabbit endothelial cells were subcultured on 96-well plates at densities ranging from 1,250 to 40,000 cells per well. After 12 hours' incubation, Alamar blue was added to each well and absorbance measured hourly from 1 to 9 hours. Sodium azide-killed cells were used as a control. Alamar blue conversion was also compared with [3H]-thymidine incorporation in the presence or the absence of mitomycin C. RESULTS: Alamar blue reduction demonstrated endothelial cell viability at all cell concentrations compared with that in killed-cell controls. The reduction varied proportionately with cell number and time, showing clearly significant differences. Conversely, [3H]-thymidine uptake demonstrated minimal DNA synthesis and little or no ability to distinguish cell number or viahility. CONCLUSIONS: Alamar blue reduction measures endothelial cell viability and can readily differentiate cell concentrations. It demonstrates several advantages over [3H]-thymidine: It can assay nonproliferating endothelial cell metabolism, it allows rapid assessment of large numbers of samples, it can differentiate endothelial cell concentrations, it is nontoxic, it is nonradioactive and allows for simple disposal, it is less costly, and it allows for continuous monitoring of endothelial cell metabolism and viability.

Specificity for activase is changed by a Pro-89 to Arg substitution in the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase.

Tobacco activase does not markedly facilitate the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1. 39) from non-Solanaceae species, including the green alga Chlamydomonas reinhardtii. To examine the basis of this specificity, we focused on two exposed residues in the large subunit of Rubisco that are unique to the Solanaceae proteins. By employing in vitro mutagenesis and chloroplast transformation, P89R and K356Q substitutions were separately made in the Chlamydomonas enzyme to change these residues to those present in tobacco. Both mutants were indistinguishable from the wild type when grown with minimal medium in the light and contained wild-type levels of holoenzyme. Purified Rubisco was assessed for facilitated activation by spinach and tobacco activase. Both wild-type and K356Q Rubisco were similar in that spinach activase was much more effective than tobacco activase. In contrast, P89R Rubisco was not activated by spinach activase but was well activated by tobacco activase. Thus, the relative specificities of the spinach and tobacco activases for Chlamydomonas Rubisco were switched by changing a single residue at position 89. This result provides evidence for a site on the Rubisco holoenzyme that interacts directly with Rubisco activase.

Mechanistic insights provided by deletion of a flexible loop at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase.

To evaluate the functions of flexible loop 6 at the active site of Rhodospirillum rubrum D-ribulose-1,5-bisphosphate carboxylase/oxygenase, the loop was truncated by cassette mutagenesis, whereby seven residues of the twelve-residue loop were excised and replaced by two glycyl residues. The purified loop-deletion mutant was totally devoid of carboxylase activity, but retained substantial catalytic competency in the enolization of ribulose bisphosphate (the initial step in the overall carboxylase pathway) and in normal processing of the six-carbon carboxylated intermediate (the terminal steps in the overall carboxylase pathway). Hence, catalytic impairment resides predominantly at the stage of carboxylation of the initial enediol(ate), a conclusion compatible with mechanistic deductions derived from crystallographic analyses. A critical role of loop 6 in the stabilization of the transition state for carboxylation is reinforced by the findings that the loop-deletion mutant displays preferentially compromised affinity for an analogue of the carboxylated intermediate relative to ribulose bisphosphate and that the mutant converts the substrate to a dicarbonyl compound as a consequence of beta-elimination of phosphate from the initial enediol(ate).

Effect of monensin and monensin and tylosin combination on feed intake variation of feedlot steers.

A trial involving four commercial feedlots and an individual feeding trial evaluated the effect of monensin and monensin/tylosin on intake variation and deaths from digestive disorders. Four commercial feedlots in Texas and Colorado fed 2,904 yearling crossbred steers (340 kg) high-grain diets containing approximately 82% grain, 8% silage and alfalfa hay, 4% fat, and 6% supplement (DM basis). Steers were allotted randomly to one of three monensin/tylosin levels: 1) no monensin or tylosin (control); 2) 22 mg/kg of monensin and 11 mg/kg of tylosin; or 3) 33 mg/kg of monensin and 11 mg/kg of tylosin. Monensin/tylosin reduced DMI (P < .05) and improved ADG (P < .05) and feed efficiency (P < .01). Intake variation associated with dry matter offered per pen was not different among treatments. In the individual feeding trial, feeding 27 mg/kg of monensin reduced (P < .10) DMI variation during grain adaptation and during d 57 to 70 and d 97 to 110 compared with the control (no monensin) diet. The magnitude of intake variance was 5 to 10 times greater with individually fed steers than with steers fed in the commercial feedlot pens. When the DMI of the individually fed steers were averaged and treated as a pen of steers, DMI variance was reduced drastically and was not different between treatments. We interpret these data to indicate that monensin and monensin/tylosin reduce feed intake variation among individual steers within a pen of steers. Pen means mask individual animal variation to the point that it is difficult to detect treatment differences.

Wet corn distillers byproducts compared with dried corn distillers grains with solubles as a source of protein and energy for ruminants.

Five trials investigated the feeding value of wet and dried corn distillers byproducts as a source of protein and energy for growing and finishing cattle and investigated the effect of heat damage on the feeding value of dried distillers byproducts. In a calf growth trial, no differences in rate of gain or protein efficiency were observed among calves fed wet distillers byproducts (wet distillers grains + thin stillage; WDB) or one of three composites of dried distillers grain + solubles (DDGS) having a low, medium, or high concentration of ADIN. A finishing trial compared the energy value of dry-rolled corn (DRC) with WDB or the three DDGS composites, fed at 40% of the diet DM replacing DRC. Cattle consuming WDB or DDGS gained faster (P < .05) and more efficiently (P < .05) than cattle fed DRC. Although gains were similar, cattle fed WDB consumed less feed (P < .10) and were more efficient (P < .10) than cattle fed DDGS. Level of ADIN in DDGS did not affect efficiency of gain (P > .10). In a lamb finishing trial, the addition of 5 or 10% ethanol did not affect (P > .10) daily gain, DMI, or feed efficiency. In two metabolism trials with steers, grain byproducts (wet distillers grains, dry distillers grains plus solubles, wet corn gluten feed, dry corn gluten feed, hominy feed) and DRC had similar effects on ruminal pH and total VFA. Feeding thin stillage or condensed solubles reduced (P < .10) ruminal pH and tended to reduce acetate:propionate. Wet corn distillers byproducts, fed at 40% of the diet DM, contain more NEg than did DRC and drying WDB reduces its NEg content. Acid detergent insoluble N is a poor indicator of protein and energy value in distillers grains.

Feeding value of wet distillers byproducts for finishing ruminants.

Yearling and calf finishing trials (replicated over 2 yr) evaluated the feeding value of wet distillers byproducts (wet distillers grains and thin stillage). An additional trial estimated the amount of thin stillage bypassing the rumen when consumed by drinking. Yearlings were 5, 10, and 20% more efficient (linear, P < .01; quadratic, P = .05), whereas calves were 2, 6, and 14% more efficient (linear, P < .01) when fed 5.2, 12.6, and 40.0% (DM basis) wet distillers byproducts, respectively, compared with cattle fed a 79% dry-rolled corn diet. Cattle fed 5.2 or 12.6% wet distillers byproducts, or the dry-rolled corn diet, received similar amounts of protein (crude or metabolizable), which exceeded the metabolizable protein requirement of all cattle. Therefore, differences in efficiency were attributed to differences in energy utilization of the diets. Wet distillers byproducts fed at 5.2, 12.6 and 40.0% contributed 80, 62, and 47% more net energy for gain than corn when fed to yearlings and 17, 33, and 29% more net energy for gain than corn when fed to calves, respectively. Wet distillers byproducts averaged 169% the energy value of corn (2.53 Mcal of NEg/kg) when fed to yearlings and 128% the energy value of corn (1.96 Mcal of NEg/kg) when fed to calves. The increased energy values cannot be explained by increased digestibility, but they may be due to a combination of factors (reduced acidosis, increased energy utilization, yeast end products, etc.) that increase the net energy content of distillers byproducts. Approximately 50% of the thin stillage consumed by drinking bypassed ruminal fermentation.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy value of hominy feed for finishing ruminants.

Three trials were conducted to evaluate the energy value of hominy feed in finishing diets for ruminants. Hominy feed contained 56.9% starch, 25.2% NDF, 11.1% CP, and 5.3% fat (DM basis). In all trials, hominy feed replaced dry-rolled corn. As the level of hominy feed or ground corn increased in a lamb digestion trial, DM digestibility decreased (P < .01); however, starch digestibility increased (P = .09). Hominy feed and ground corn interacted (linear, P = .08) with respect to NDF digestibility. As the level of ground corn increased, NDF digestibility decreased (linear, P = .10). In a finishing trial, yearling heifers were fed either hominy feed with or without fat added to hominy feed at 0, 13.3 (.67% added fat), 26.7 (1.33% added fat), and 40.0% (2.0% added fat) of diet DM. Fat addition did not interact with hominy feed level. Heifers fed 13.3 or 26.7% hominy feed or hominy feed + fat consumed more DM (P = .10) than heifers fed the 0 or 40.0% diets; however, gain and feed efficiency were similar. In a second finishing trial, steers fed 40% (diet DM) hominy feed consumed more (P = .05) DM, but daily gain and feed efficiency were similar to those of cattle fed dry-rolled corn. Steers fed all-concentrate diets were more efficient (P < .01) than cattle fed 7.5% forage. Results indicated that expeller-extracted hominy feed contained 1.35 Mcal of NEg/kg, or 87% of the energy of corn, when included at levels up to 40% of cattle finishing diets, despite its containing 20% less starch than corn.

Time-Resolved X-ray Diffraction Study of Solid Combustion Reactions.

Real-time synchrotron diffraction has been used to monitor the phase transformations of highly exothermic, fast self-propagating solid combustion reactions on a subsecond time scale down to 100 milliseconds and in some instances to 10 milliseconds. Three systems were investigated: Ti + C --> TiC; Ti + C + xNi --> TiC + Ni-Ti alloy; and Al + Ni --> AlNi. In all three reactions, the first step was the melting of the metal reactants. Formation of TiC in the first two reactions was completed within 400 milliseconds of the melting of the Ti metal, indicating that the formation of TiC took place during the passage of the combustion wave front. In the Al + Ni reaction, however, passage of the wave front was followed by the appearance and disappearance of at least one intermediate in the afterburn region. The final AlNi was formed some 5 seconds later and exhibited a delayed appearance of the (210) reflection, which tends to support a phase transformation from a disordered AlNi phase at high temperature to an ordered CsCl structure some 20 seconds later. This new experimental approach can be used to study the chemical dynamics of high-temperature solid-state phenomena and to provide the needed database to test various models for solid combustion.

Patterns of labor absorption by occupation in the Dominican Republic.

"The purpose of this article is to describe and analyze patterns of labor absorption by occupation in the Dominican Republic using national population census data." The author develops a measure that facilitates the identification of patterns of labor absorption into various occupations. The results, based on data for the period 1970-1981, show sharp differentials by sex and zone. It is found that the service sector is absorbing more workers but that agriculture is not, even in rural areas.

Sexual criminality and hypnotizability.

Thirty-three sexual offenders, 18 of whom had been convicted of rape, nine of pedophilia, and six of incest, were studied. Two thirds of the subjects had histories of "spontaneous self-hypnotic" experiences (dissociations); seven of these were DSM-III multiples and six were probable multiples. This group had very high hypnotizability scores. The other one third without histories of "spontaneous self-hypnosis" had normal scores. It was concluded that spontaneous self-hypnosis contributed to the perpetration of the crimes in many of these cases, although other factors also directed the antisocial behaviors.

Auditory hallucinations and schizophrenia.

Forty-five patients with auditory hallucinations were studied. Sixty per cent proved to be excellent hypnotic subjects with multiple personalities. These latter patients received 11 different diagnoses by clinicians, predominantly those related to schizophrenia or an affective illness. Because patients with multiple personalities frequently have hallucinations, delusions, paranoid ideas and bizarre behaviors, they may be misdiagnosed as some form of schizophrenia.

Seasonal variations in apparent photosynthesis among plant stands of different soybean cultivars.

The CO2- and H2O-exchange rates between soybean canopies and the atmosphere were measured in three mobile chambers (4 m(3)). Each chamber stopped at 8 or 9 plots (3.1-m(2) ground area) every 25 min. Diurnal and seasonal CO2-exchange rates (CER) of 13 soybean (Glycine max (L.) Merr.) cultivars are summarized here. The oldest two cultivars, released in 1927 and 1932, had the lowest CER values. The CER usually decreased in the afternoon (23.4 vs 27.8 µmol CO2 m(-2) s(-1) at 1.6 mmol photons m(-2) s(-1)), except shortly after rainfall. During a drought, these reductions occurred earlier in the day and were more pronounced. We present evidence for a nonstomatal component of the CO2 flux-reaction system causing CER reductions during a water stress. Daytime CER values were not correlated with temperature (24-34° C), but nighttime values were (15-25° C, r=0.85,* n=41).