Detection of diphtheria toxin and its degradation products by using immunoenzyme analysis

An enzyme immunoassay system for the detection of diphtheria toxin and the products of its degradation has been developed on the basis of the enzyme-linked immunosorbent assay. To sensitize the assay plates, bivalent F(ab)2-fragments of purified antidiphtheria antibodies at a concentration of 10.0 micrograms/ml, obtained from the blood serum of hyperimmunized rabbits, have been used. Specific conjugates have been prepared with the use of F(ab)2-fragments of purified antidiphtheria antibodies obtained from the blood serum of hyperimmunized horses. The optimum time and temperature conditions of the assay have been established. The new enzyme immunoassay system permits the detection of diphtheria toxin and the products of its degradation in biological substrates at a concentration of 10.0-5.0 ng/ml.     

Determination of the toxigenicity of Corynebacterium diphtheriae by using paper indicator disks

The method for the determination of the toxigenicity of C. diphtheriae by means of discs impregnated with diphtheria antitoxin is proposed. The discs can be prepared long before use and stored for a year. The determination of toxigenicity with these discs is not inferior in its sensitivity to the routine procedure of the immunoprecipitation test. The disc method decreases the consumption of unavailable diphtheria antitoxin by 10 times, that of culture media by 2-2.5 times: besides, it is less labor consuming.     

A method for determining the toxigenicity of micromycetes]

A method is suggested to determine toxigenicity of microscopic fungi from genera Aspergillus, Penicillium, Fusarium, etc. which contaminate fodder, food products and environment objects. The method is based on the property of micromycetes isolated from fodder, food products and environment objects to produce mycotoxins under optimal conditions of their cultivation on the nutrient media. Their further extraction by the organic solvent, evaporation and emulsification of the extract and its peroral introduction to young female rats cause a disease and death of animals. The suggested method may be used for recognizing and preventing mycotoxicoses of farm animals and poultry.     

The diagnostic effectiveness of an immunoenzyme test system for determining diphtheria toxin antigens in the blood serum in a clinical laboratory trial

The data on the approbation of the diagnostic value of the enzyme immunoassay (EIA) system for the determination of diphtheria toxin in the blood sera of diphtheria patients and persons suspected for diphtheria are presented. The EIA system was prepared on the basis of F(ab)2 fractions of purified antidiphtheria antibodies. 240 serum samples from diphtheria and tonsillitis patients and from healthy persons were studied. Diphtheria toxin was determined in all patients with the toxic form of diphtheria and in 41.3% of patients with its localized forms. Blood was taken mainly of the first week of the disease. In healthy persons the results of EIA were negative. Thus, the trial of the assay system in a clinical laboratory showed its good diagnostic effectiveness. The use of this EIA system in medical practice is believed to be quite promising.     

The immunization of children with combined diphtheria and tetanus vaccine in Sweden

Two groups derived from 97 children three-four months of age were vaccinated with diphtheria and tetanus vaccines containing either a routinely prepared diphtheria toxoid or a more purified preparation. Two injections were given with an interval of one month and a third injection was given one year after the first. Prior to the third injection no child was without protection against diphtheria, i.e. had an antitoxin titre less than 0.01 IU ml-1. After the third injection 95 and 94% of the children vaccinated with the routinely and more purified diphtheria toxoids, respectively, had diphtheria antitoxin titres greater than 1 IU ml-1 (estimated to provide protection for at least ten years). Systemic reactions such as fever and malaise occurred in five children. Local reactions greater than 10 cm were observed in three children and reactions greater than 5 but less than or equal to 10 cm were seen in 14% of the children. The routinely prepared combined diphtheria and tetanus vaccine, DT, produced very good immunity against diphtheria with moderate side effects. The use of a more purified diphtheria toxoid in the combined vaccine produced the same immunity and side effects.     

Relationship between the culture medium and the fatty acid composition of diphtheria and non-pathogenic corynebacteria]

The gasochromatic method was applied to the study of the cellular fatty acids composition in diphtheria and nonpathogenic corynebacteria (diphtheroids and psendo diptheria bacillus). Marked differences in the content of unsaturated fatty acids were revealed in them. Thus, palmito leic acid served the preponderant unsaturated fatty acid in Corynebacteria diphtheriae, and unsaturated fatty acids with 18 carbon atoms (octadeconoic and linoleic)--in nonpathogenic corynebacteria. The mentioned changes permit use this sign as differential. When grown on Loeffler's medium all the corynebacteria under study had a similar fatty acid composition characterized by the prevalence of unsaturated fatty acids with 18 carbon atoms. On the basis of studying the fatty acid spectrum of the nutrient media used it is supposed that one of the factors determining the revealed dependence of the corynebacterial fatty acid composition on the culture medium was the fatty acid composition of the latter.     

Rickettsia conorii and prowazekii plaque study in a chick fibroblast cell culture]

The results of the study of plaques formed by R. conorii (strain M 1) and R. prowazeki (strain E and erythromycin-resistant strain E) in chick fibroblast cell culture are presented. In this study the tissue monolayer was inoculated with rickettsiae suspended in various media, and media of different composition were used in the nutrient cover and for cell cultivation. The maximum plaque formation was observed under the following conditions: the monolayer of chick fibroblasts (seeding density was not less than 375,000 cells per 1 sq. cm) was grown in medium 199 with 5-10% of fresh fetal or calf serum and inoculated with rickettsiae suspended in heart-brain infusion; the nutrient cover was prepared on the basis of Seakem agarose (USA) and contained medium 199 (without antibiotics) and 10% of fresh fetal or calf serum. In these conditions R. conorii formed plaques 2 mm in diameter, the first plaques being observed on day 6, and most of them on days 7-9; the both strains of R. prowazeki formed plaques 1 mm in diameter, the first plaques being observed on days 8-9, and most of them on days 10-13.     

Nutrition in the life cycle assessment of foods—function or impact?

Purpose

This work provides an unambiguous conceptual framework for inclusion of nutrition in Life Cycle Assessments (LCAs) of food that enables the distinction between two different roles of nutrition, namely serving as the basis of food comparisons via the functional unit and as an impact pathway that links food ingestion with human health effects.

Methods

We compare how nutritional aspects have been considered in the functional unit of published LCAs of food with the procedural requirements for ensuring comparability of the functional units. We consider the relevance of nutrient profiling models for assessing food- and diet-related health damages and benefits in the context of LCAs of food. We finally recommend a method that will enable a systematic, comparative, and holistic assessment of the marginal health effect of food products on human health.

Results and discussion

Satiety is proposed as a central attribute for comparisons of food products, while weighted measures of nutrient content are suggested to be largely misplaced as part of the functional unit. In contrast, nutritional measures have a large role to play in assessing the human health impacts of the marginal ingestion of specific food products. Such measures should enable a direct quantification of human health effect and benefits and should take advantage of robust epidemiological evidence.

Conclusions

Nutritional measures enter into both the functional unit in the form of satiety measures and into the calculation of impacts in the form of the marginal influence of the specific food item on the human health impact of the overall diet. To enhance the differentiation of health impacts at the level of individual food items, it is recommended to combine the nutrient balance indicator with the DALY Nutritional Index (DANI) in each specific dietary context.

     

Minimal Medium Recovery of Thermally Injured Salmonella senftenberg 4969

Exposure of Salmonella senftenberg 4969 to sublethal heating in phosphate buffer, pH 7·0, at 52· produced thermally injured cells characterized by their relative inability to form colonies on trypticase soy yeast extract agar compared to minimal medium (M9) agar. During subsequent incubation at 37· in liquid media, more injured cells were capable of repair in M9 than in nutrient media used for pre-enrichment purposes. M9 was superior to lactose broth as a liquid holding medium to restore the ability of injured cells to grow on both rich and selective agar media. The addition of food products produced a more favourable environment for the repair of thermally injured cells in M9 rather than lactose broth. Pre-enrichment in M9 was 100 times more effective than using lactose broth as the preliminary step in the detection of S. senftenberg in laboratory pasteurized liquid egg albumen.     

Double-antibody solid-phase enzyme immunoassay for the detection of staphylococcal enterotoxin A.

A simple double-antibody enzyme immunoassay that uses a microtechnique was developed for detecting staphylococcal enterotoxin A in food products. Sample preparation can be completed in less than 15 min. Assay sensitivity ranges from 0.4 ng (20-h test time) to 3.2 ng (1- to 3-h test time) of toxin per ml of prepared sample. Separation and detection of enterotoxin from spiked food products ranged between 72 and 98% of the amount added.     

Der schmale Grat zwischen Prävention und Placebo: Nahrungsergänzungsmittel

Consumers expect vitamin and mineral supplements to protect them against diseases. In Germany the legal basis of food supplements is the national food law, therefore any advertising regarding diseases is forbidden. Since there exist no definition and no legal basis for the product group by now, there are many products with illegal advertisement and without any health effect in the market. Furthermore the differentiation from other product categories, especially drugs, is difficult. Food supplements can help to meet the needs for critical nutrients and are able to ameliorate the supply of health protecting substances. This is especially important for risk groups with higher nutrient requirements or low energy intake. The bioavailability of substances from supplements is mostly better than from food. Therefore dosages should correspond to those taken by normal food consumption. It is the pragmatic way to use food supplements in order to prevent inadequate nutrient intake especially in risk groups.     

Double-antibody solid-phase enzyme immunoassay for the detection of staphylococcal enterotoxin A.

A simple double-antibody enzyme immunoassay that uses a microtechnique was developed for detecting staphylococcal enterotoxin A in food products. Sample preparation can be completed in less than 15 min. Assay sensitivity ranges from 0.4 ng (20-h test time) to 3.2 ng (1- to 3-h test time) of toxin per ml of prepared sample. Separation and detection of enterotoxin from spiked food products ranged between 72 and 98% of the amount added.     

Cultivation of Pseudomonas aeruginosa in media with chlorella fermentative hydrolysate as nutrient base

The specific features of the growth of P. aeruginosa in media prepared with the use of Chlorella fermentative hydrolysate as nutrient basis were studied. The accumulation of microbial biomass was shown to depend on increased content of amino nitrogen in the media, while the effectiveness of the pyocyanin formation was linked with decreased content of amino nitrogen and a rise in the amount of sodium chloride.     

Postconsumption Sewage Treatment in Environmental Systems Analysis of Foods

Food in general has a high nutrient content, which essentially passes through the human organism and ends up in the sewage system. This high nutrient content in sewage, however, is rarely included in environmental systems analyses of food products or production systems. At the same time, several studies on sewage systems have shown the significance of plant nutrients in sewage system outlets. This means that important environmental effects may be neglected in environmental systems studies of food.
We present a method for including emissions that occur after food consumption in environmental systems analyses of foods. The method uses easily accessible input data to calculate the postconsumption emissions caused by certain food products.
The method was tested by completing the results for eutrophication from seven life-cycle assessments (LCAs) on food products with the corresponding emissions caused by outlets from a sewage plant. The results showed that postconsumption eutrophication was a significant part of the products' total life-cycle impact, ranging from 5.5% (beef) to 86% (apples).
The conclusion is that including postconsumption emissions is important for studies aiming at mapping a product's life cycle to find the most environmentally relevant parts, as well as for eco-labeling purposes. If the purpose of the study is decision support, the postconsumption phase should be included where the decision affects this part of the system, otherwise not. When products are compared, postconsumption emissions should be included if their nutrient contents differ.     

Comparison of Brilliant Green Agar and Hektoen Enteric Agar Media in the Isolation of Salmonellae from Food Products

Brilliant Green (BG) agar and Hektoen enteric (HE) agar media were compared for their efficiency in isolating salmonellae from various food products. Of the 11,226 food specimens examined, 1,662 (or 14.9%) yielded salmonellae. Of this number, 1,475 (88.7%) were recovered from BG agar and 1,315 (79.1%) were recovered from HE agar media. The results indicate that BG agar is more effective in isolating salmonellae from food products. A smaller subsidiary study showed HE agar to be more selective than BG agar. Four hundred ten specimens yielded 92 nonlactose-fermenting isolants other than salmonellae on BG agar and only 11 such isolants on HE agar.     

Anomalous potential response and (Na+ + K+)-ATPase in in vitro frog gastric mucosa

In general, increasing K+ on the nutrient side decreases the transmucosal PD (nutrient becomes more negative) but after bathing the mucosa in zero K+ media for about 30 min, or longer, elevation of K+ on the nutrient side increases the PD, an anomalous effect. In Cl- media, increasing nutrient K+ from zero to 4 mM produces an increase in PD (an anomalous response) of 3.1 and 5.3 mV in 2 and 5 min, respectively. Ouabain (10(-3) M) to the nutrient side abolished the anomalous response as did removal of Na+ (choline for Na+) from bathing media. In SO4(2-) media (SO4(2-) for Cl-), a significant anomalous PD response was observed when K+ on the nutrient side was increased from zero to 1, 2 or 3 mM but not to higher K+ concentrations. In this case, ouabain also abolished the anomalous response. It is postulated, on the basis of the effects of ouabain and the use of choline media, that an electrogenic (Na+ + K+)-ATPase pump is present on the nutrient-facing membrane in which more Na+ than K+ are transported per cycle.     

Specific characteristics of composition of synthetic nutrient media for cultivation of Hemophilus influenzae type b from the standpoint of bacterial metabolism

In many countries vaccination against Haemophilus influenzae of type b (Hib) has permitted the liquidation of severe generalized forms of infections caused by these bacteria. The vaccine is obtained on the basis of Hib capsular polysaccharide. To obtain pure capsular polysaccharide, Hib should be cultivated on synthetic nutrient media. The present review deals with the data substantiating the advantages of using synthetic nutrient media for the cultivation of these bacteria with a view to obtaining pure capsular polysaccharide.     

Food Web Assembly at the Landscape Scale: Using Stable Isotopes to Reveal Changes in Trophic Structure During Succession

Food webs are increasingly evaluated at the landscape scale, accounting for spatial interactions involving different nutrient and energy channels. Also, while long viewed as static, food webs are increasingly seen as dynamic entities that assemble during vegetation succession. The next necessary step is, therefore, to link nutrient flows between ecosystems to local food web assembly processes. In this study, we used a 100-year salt marsh succession in which we investigated the long-term changes in food web organization, especially focusing on the balance between internal versus external nutrient sources. We found that during food web assembly, the importance of internal (terrestrial) nutrient cycling increases at the expense of external (marine) inputs. This change from external to internal nutrient cycling is associated with strong shifts in the basis of energy channels within the food web. In early succession, detritivores are mostly fuelled by marine inputs whereas in later succession they thrive on locally produced plant litter, with consequences for their carnivores. We conclude that this 100 years of food web assembly proceeds by gradual decoupling of terrestrial nutrient cycling from the marine environment, and by associated rearrangements in the herbivore and detritivore energy channels. Food web assembly thus interacts with nutrient and energy flows across ecosystem boundaries.     

Taurine and zoo felids: considerations of dietary and biological tissue concentrations

Taurine (TAU) is an essential amino acid required in the diets of Felidae at concentrations ranging between 0.04 and 0.2% on a dry matter (DM) basis (in purified, highly digestible diets, and canned diets, respectively). Although the domestic cat seems to be an appropriate physiologic model for zoo felids, it is sometimes difficult to assess TAU status in zoo feeding programs owing to scattered information on feed ingredient TAU content as well as a lack of normal ranges for assessment of TAU in biological tissues. Knowing that TAU is required in the formulation of hand‐rearing diets for exotic felids, the TAU content of 38 ingredients or products used in zoo carnivore feeding or hand‐rearing programs was summarized, including 21 new feedstuffs for which TAU data were previously lacking. The kitten milk replacer contained a lower than expected value for TAU. Commercially prepared frozen or canned meat products, seafood products, whole rodent prey, and most strained meat jarred baby foods contained adequate TAU; chunk meats, and some specific types of jarred baby food meats were considerably lower in TAU content (≤0.10% DM) than other foodstuffs. TAU concentrations in plasma and whole blood of eight spp. of zoo felids sampled opportunistically fell within reference ranges for domestic cats (80–120 and 300–600 nmol/ml in plasma and whole blood, respectively). Plasma concentrations are a useful measure of dietary impact, whereas whole blood concentrations seem to reflect tissue storage of this nutrient. Zoo Biol 26:517–531, 2007. © 2007 Wiley‐Liss, Inc.