Demonstration of safety of probiotics -- a review

Probiotics are commonly defined as viable microorganisms (bacteria or yeasts) that exhibit a beneficial effect on the health of the host when they are ingested. They are used in foods, especially in fermented dairy products, but also in pharmaceutical preparations. The development of new probiotic strains aims at more active beneficial organisms. In the case of novel microorganisms and modified organisms the question of their safety and the risk to benefit ratio have to be assessed. Lactic acid bacteria (LAB) in foods have a long history of safe use. Members of the genera Lactococcus and Lactobacillus are most commonly given generally-recognised-as-safe (GRAS) status whilst members of the genera Streptococcus and Enterococcus and some other genera of LAB contain some opportunistic pathogens. Lactic acid bacteria are intrinsically resistant to many antibiotics. In many cases resistances are not, however, transmissible, and the species are also sensitive to many clinically used antibiotics even in the case of a lactic acid bacteria- associated opportunistic infection. Therefore no particular safety concern is associated with intrinsic type of resistance. Plasmid-associated antibiotic resistance, which occasionally occurs, is another matter because of the possibility of the resistance spreading to other, more harmful species and genera. The transmissible enterococcal resistance against glycopeptide antibiotics (vancomycin and teicoplanin) is particularly noteworthy, as vancomycin is one of the last effective antibiotics left in the treatment of certain multidrug-resistant pathogens. New species and more specific strains of probiotic bacteria are constantly identified. Prior to incorporating new strains into products their efficacy should be carefully assessed, and a case by case evaluation as to whether they share the safety status of traditional food-grade organisms should be made. The current documentation of adverse effects in the literature is reviewed. Future recommendations for the safety of already existing and new probiotics will be given.     

LENGTH OF WORK-WEEK IN THE USA IN THE FUTURE

There is a growing concern in die labor sector to reduce stresses in the work place and the associated strains and adverse effects on health which result from newer forms of tasks that workers are increasingly called upon to perform. One approach to reducing stresses is to reduce the work-week (fewer hours per week). Social expectation of longer vacations and leisure time, demographic changes, and changes in the nature of die work and attitudes towards work also support this trend. The objective of this position paper is to consider the implication of such a move and the feasibility of this approach. Specifically, we consider the effects of a shorter work-week on productivity and economy and discuss the various patterns of shorter work-week. Finally, we present our position on die pattern of the shorter work-week in the United States in the future.     

A kinetic study of the metathesis of propene on a rhenium-aluminium catalyst

Based on integral kinetic measurements and in accordance with the results of previous investigations, two mechanistic initial rate expressions based on different reaction mechanisms have been found to be statistically equivalent. Applying the Boudart criteria in a test for the physical significance of the parameter estimates, only one of the suggested expressions is significant and the corresponding reaction mechanism is, therefore, considered adequate.     

Current-switching half adder

A new current-switching half adder is described; rise and fall times of about 3 ns have been obtained.     

Liver injury in abdominal trauma. Review of the literature and personal observations

The association of infantile diarrhoea with the occurrence of Candida species and their different morphological cell forms (pseudohyphae and/or blastospores) in faeces was studied in children of 0-15 months in a developing community (Lahore, Pakistan) where malnutrition is prevalent. Stool samples from 119 patients admitted to the Diarrhoea Treatment Unit, Department of Pediatrics, King Edward Medical College, and 46 healthy children were investigated for yeasts, bacteria, viruses and parasites. Salmonella and enteropathogenic Escherichia coli were seen in 13 (11%) each of the cases while Candida was the most frequent micro-organism, grown in cultures from 38 (32%) of the diarrhoea cases. C. tropicalis dominated (19%) over C. albicans (6%) and C. parapsilosis (3%). However, in a great number of cases (23, equals 19%), Candida did not grow in cultures but blastospores and/or pseudohyphae were seen on microscopical examination. Other Candida species and yeasts were relatively more common in the control group. Candida albicans, C. tropicalis and C. parapsilosis were the only identified agents in 23 of the cases (19%). The characteristic clinical findings in children with Candida as the only identified pathogen were malnutrition (69%), age less than 8 months (90%), and microscopically identified pseudohyphae in faecal smears (71%).     

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Two detoxification mechanisms working in the marine diatom Thalassiosira weissflogii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl₂ concentrations. T. weissflogii cells responded by synthesizing metal-binding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and γ-glutamylcysteine (γ-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that glutathione could also be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and γ-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg° and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P < 0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.     

Structure and degree of polymerisation of fructooligosaccharides present in roots and leaves of Stevia rebaudiana (Bert.) Bertoni

Fructooligosaccharides have been isolated from roots and leaves of Stevia rebaudiana, by hot aqueous extraction, followed by precipitation with ethanol. Their structure has been determined using methylation and NMR analysis, MALDI-TOF, and ESI-MS. Fructooligosaccharides contained almost exclusively (2→1)-linked β-fructofuranosyl, with terminal α-glucopyranosyl and β-fructofuranosyl units. MALDI-TOF and ESI-MS analyses showed the wide range of degree of polymerisation (DP) present in various extracts. From roots and leaves, three different fractions gave profiles of homologous series, with DPs ranging up to 17 with MALDI-TOF and 19 using ESI-MS. These inulin-type fructooligosaccharides were the major component of extracts from S. rebaudiana roots and significant components from the leaves.     

Deriving Efficient Porous Heteroatom‐Doped Carbon Electrocatalysts for Hydrazine Oxidation from Transition Metal Ions‐Coordinated Casein

In this work, the synthesis of high‐performance, metal ion‐imprinted, mesoporous carbon electrocatalysts for hydrazine oxidation reaction (HzOR) using casein or a family of phosphoproteins derived from cow's milk as a precursor is shown. The synthesis is made possible by mixing trace amounts of non‐noble metal ions (Fe³⁺ or Co²⁺) with casein and then producing different metal ions‐functionalized casein intermediates, which upon carbonization, followed by acid treatment, lead to metal ion‐imprinted catalytically active sites on the materials. The materials effectively electrocatalyze HzOR with low overpotentials at neutral pH and exhibit among the highest electrocatalytic performances ever reported for carbon catalysts. Their catalytic activities are also better than the corresponding control material, synthesized by carbonization of pure casein and other materials previously reported for HzOR. This work demonstrates a novel synthetic route that transforms an inexpensive protein to highly active carbon‐based electrocatalysts by modifying its surfaces with trace amounts of non‐noble metals. The types of metal ions employed in the synthesis are found to dictate the electrocatalytic activities of the materials. Notably, Fe³⁺ is found to be more effective than Co²⁺ in helping the conversion of casein into more electrocatalytically active carbon materials for HzOR.