Acidic phospholipids are required during solubilization of amino acid transport systems of Lactococcus lactis.

The branched-chain amino acid transport system of Lactococcus lactis was solubilized with n-octyl beta-D-gluco-pyranoside and reconstituted into proteoliposomes. Transport activity was recovered only when solubilization was performed in the presence of acidic phospholipids. Omission of acidic phospholipids during solubilization resulted in an inactive transport protein and the activity could not be restored in the reconstitution step. Similar results have been obtained for the arginine/ornithine exchange protein from Pseudomonas aeruginosa and L. lactis. Functional reconstitution of the transport protein requires the presence of aminophospholipids or glycolipids in the liposomes (Driessen, A.J.M., Zheng, T., In't Veld, G., Op den Kamp, J.A.F. and Konings, W.N. (1988) Biochemistry 27, 865-872). We propose that during the detergent solubilization the acidic phospholipids protect the transport systems against denaturation by preventing delipidation.     

Bringing a probiotic-containing functional food to the market: microbiological, product, regulatory and labeling issues

Properly formulated probiotic-containing foods offer consumers a low risk, low cost dietary component that has the potential to promote health in a variety of ways. Several such products are available commercially, although markets in Japan and Europe are more developed than in the USA. Once healthful attributes of a probiotic product have been identified, there remain microbiological, product, regulatory and labeling issues to be addressed prior to marketing. Microbiological and product issues include safety, effective scale-up for manufacturing, definition of probiotic activity, probiotic stability in the product over the course of product manufacture, shelf-life and consumption, definition of effective dose and target population(s), and development of quality assurance approaches. Examples of probiotic-containing foods are given. Regulatory and labeling issues are complicated because they differ for each country, but are likewise critical because they provide the means for c ommunication of the product benefits to the consumer. The regulatory climate worldwide appears to be one of caution about overstating the benefits of such products but at the same time not preventing corporate commitment to marketing.     

Exploring the behavioral and cognitive phenotype of KBG syndrome

KBG syndrome is a neurodevelopmental disorder, caused by dominant mutations in ANKRD11, that is characterized by developmental delay/intellectual disability, mild craniofacial dysmorphisms, and short stature. Behavior and cognition have hardly been studied, but anecdotal evidence suggests higher frequencies of ADHD‐symptoms and social‐emotional impairments. In this study, the behavioral and cognitive profile of KBG syndrome will be investigated in order to examine if and how cognitive deficits contribute to behavioral difficulties. A total of 18 patients with KBG syndrome and a control group consisting of 17 patients with other genetic disorders with comparable intelligence levels, completed neuropsychological assessment. Age‐appropriate tasks were selected, covering overall intelligence, attention, memory, executive functioning, social cognition and visuoconstruction. Results were compared using Cohen's d effect sizes. As to behavior, fewer difficulties in social functioning and slightly more attentional problems, hyperactivity, oppositional defiant behavior and conduct problems were found in the KBG syndrome group. Regarding cognitive functioning, inspection of the observed differences shows that patients with KBG syndrome showed lower scores on sustained attention, cognitive flexibility, and visuoconstruction. In contrast, the KBG syndrome group demonstrated higher scores on visual memory, social cognition and emotion recognition. The cognitive profile of KBG syndrome in this sample indicates problems in attention and executive functioning that may underlie the behavior profile which primarily comprises impulsive behavior. Contrary to expectations based on previous (case) reports, no deficits were found in social cognitive functioning. These findings are important for counseling purposes, for tailored education planning, and for the development of personalized intervention.     

Immunogold-silver labeling in histology

Immunogold-silver staining is a relatively new technique in light-microscopic immunocytochemistry. It is based on silver enhancement of 1 to 10 nm gold probes immunologically bound to antigenic determinants in tissue sections. The detection efficiency of this third-generation detection technique is compared to that of the peroxidase-based ABC technique in routinely processed, paraffin-embedded, human biopsy material.     

Book reviews

Book reviewed in this article: Morphogenetic Hormones of Arthropods, Volume 1, Part 1. Ed.: A. P. Gupta. Stavenga, D. G. & Hardie, R. C., eds.: Facets of Vision. Harris, K. M. & P. R. Scott (Eds). Crop protection information: an international perspective: proceedings of the International Crop Protection Information Workshop, 1989. C.A.B. International, Wallingford. Aphid-Plant Genotype Interactions. Edited by R. K. Campbell and R. D. Eikenbary.     

An in-vitro meat model for the immediate bactericidal effect of lactic acid decontamination on meat surfaces

An in-vitro model of the lactic acid decontamination (LAD) of meat is described. As LAD is a disinfection rather than a preservation process the model is based on the inactivation kinetics of bacteria in a suspension of pork skin. The model takes account of interfering factors present in nature, such as microbial interactions, leaching of organic material from the meat surfaces and buffering activity.     

Sensitive and specific method for the simultaneous determination of natural and synthetic catecholamines and 3,4-dihydroxyphenylglycol in microdialysis samples

The relatively new technique of microdialysis provides new possibilities for investigating in vivo the functioning of the sympathetic nervous system. The small sample volumes obtained, however, are a great challenge for analytical chemists. We report here a HPLC method for measuring in one run both natural and synthetic catecholamines [dopamine, (nor)epinephrine, -methylnorepinephrine, isoproterenol and epinine] and the intraneuronal metabolite 3,4-dihydroxyphenylglycol in small microdialysis samples after derivatization with the fluorogenic agent 1,2-diphenylethylenediamine. No prior clean-up step is necessary. N-Ethylmaleimide is necessary for preventing an inhibitory action on derivatization occurring in in vivo microdialysis samples. The method can handle large numbers of samples, is sensitive (on-column detection limits 30 to 200 fg) and reproducible (RSD 1 to 7%). Recovery characteristics of the commercial microdialysis probe used (CMA/20) were extensively investigated both in vitro and in vivo at various perfusion rates; for practical purposes a rate of 2 μl/min and sampling at 10-min intervals was found to be workable and to give good and reproducible recoveries (50 to 70%).