Body odor evoked potentials: a new method to study the chemosensory perception of self and non‐self in humans

A new method will be presented which allows the perception of body odors in humans to be studied objectively. The analysis of body odor‐evoked potentials was used to investigate if and how the human brain is able to differentiate self from non‐self body odor for the first time. Six subjects (three females) participated in two experimental sessions. In each session, two body odors (axillary hair) were presented within an olfactory oddball paradigm. One of the odors was collected from the subject and the other from an odor donor of the same sex. In the first session the subjects' attention was distracted to a secondary task (passive paradigm), in the second session the subjects were asked to actively differentiate the odors (active paradigm). For the EEG recordings the odors were presented within a constantly flowing airstream. The results show that the subjects could hardly differentiate the body odors subjectively. However, it could be demonstrated that the central nervous processing of one's own odor was faster than the processing of the chemosensory non‐self signal. Moreover, in the active paradigm, the potentials appeared to be larger when the subjects perceived their own body odor. The conclusion is reached that the measurement of chemosensory event‐related potentials (CSERP) is the method of choice for the investigation of HLA‐associated body odors. This revised version was published online in July 2006 with corrections to the Cover Date.     

The human brain is a detector of chemosensorily transmitted HLA-class I-similarity in same- and opposite-sex relations

Studies on subjective body odour ratings suggest that humans exhibit preferences for human leucocyte antigen (HLA)-dissimilar persons. However, with regard to the extreme polymorphism of the HLA gene loci, the behavioural impact of the proposed HLA-related attracting signals seems to be minimal. Furthermore, the role of HLA-related chemosignals in same- and opposite-sex relations in humans has not been specified so far. Here, we investigate subjective preferences and brain evoked responses to body odours in males and females as a function of HLA similarity between odour donor and smeller. We show that pre-attentive processing of body odours of HLA-similar donors is faster and that late evaluative processing of these chemosignals activates more neuronal resources than the processing of body odours of HLA-dissimilar donors. In same-sex smelling conditions, HLA-associated brain responses show a different local distribution in male (frontal) and female subjects (parietal). The electrophysiological results are supported by significant correlations between the odour ratings and the amplitudes of the brain potentials. We conclude that odours of HLA-similar persons function as important social warning signals in inter- and intrasexual human relations. Such HLA-related chemosignals may contribute to female and male mate choice as well as to male competitive behaviour.     

Lifestyle Intervention Decreases Urine Trimethylamine N‐Oxide Levels in Prepubertal Children with Obesity

Objective

Early lifestyle interventions in children with obesity decrease risk of obesity and metabolic disorders during adulthood. This study aimed to identify metabolic signatures associated with lifestyle intervention in urine samples from prepubertal children with obesity.

Methods

Thirty‐four prepubertal children with obesity were studied before and after a 6‐month lifestyle intervention program, and anthropometric, metabolic, and nutritional variables were collected. A nuclear magnetic resonance approach was applied to obtain the metabolomic profile from urine samples. Partial least squares‐discriminant analysis (PLS‐DA) was used to achieve group classification and variable importance on projection (VIP) for biomarker selection.

Results

The intervention reduced caloric intake by 10% (P < 0.05) and BMI standard deviation score by 0.47 SD (P < 0.001). PLS‐DA identified trimethylamine N‐oxide (TMAO, VIP = 2.21) as the metabolite with the highest discrimination properties between groups. Urine TMAO levels were reduced after the intervention (P < 0.05). TMAO is a biomarker of cardiovascular disease risk and is a product of gut microbiota‐dependent metabolism of certain dietary compounds, including choline. Notably, changes in TMAO levels after the intervention did not correlate to differences in choline intake but were inversely associated with fiber intake (P < 0.05).

Conclusions

These results indicate that lifestyle intervention decreases TMAO levels in children with obesity.

     

Cerebral gigantism: report on two familial cases (author's transl)

Two cases of cerebral gigantism occurring in related boys (cousins of 3rd degree) are discussed. It is difficult to argue from these cases in favour of a precise type of hereditary transmission. The hypothesis of a dominant trait with weak penetrance cannot be excluded. A genetic heterogeneity of the Sotos syndrome is very likely.     

Cloning and expression of the ltf gene of bacteriophage T5.

The unique 5-kilobase BamHI fragment of bacteriophage T5 was cloned into plasmid pBR322. Location of the intact ltf gene on the cloned fragment was demonstrated by complementation of the ltf mutation of phage T5hd-2, identification of a plasmid-coded polypeptide of the same molecular weight as the polypeptide forming the L-shaped tail fibers, which binds to anti-T5 antibodies; and analyses of transposon Tn1000 insertions.     

Location of genes D16, D17, and N4 encoding tail proteins on the physical map of bacteriophage T5

Bacteriophage T5 DNA fragments were cloned into plasmid pBR322. Recombinant plasmids complementing T5 amber mutants were isolated, and used as hybridization probes with T5 DNA in Southern blots. Employing this approach the three T5 genes D16, D17, and N4 were mapped with respect to the physical map of T5, and shown to be located at 74%, 72%, and 82% of the genome, respectively.     

Cloning, sequencing, and recombinational analysis with bacteriophage BF23 of the bacteriophage T5 oad gene encoding the receptor-binding protein.

Binding of bacteriophage T5 to its receptor, the Escherichia coli FhuA protein, is mediated by tail protein pb5. In this article we confirm that pb5 is encoded by the T5 oad gene and describe the isolation, expression, and sequencing of this gene. In order to locate oad precisely, we analyzed recombinants between BF23, a T5-related phage with a different host range, and plasmid clones containing segments of the T5 chromosome. This analysis also showed that oad has little or no homology with hrs, the analogous BF23 gene. We were able to overproduce a protein that comigrates with pb5 after fusing a 2-kb segment containing oad to a phage T7 promoter. This segment contains an open reading frame that can encode a protein of the appropriate size. Its deduced amino acid sequence does not closely resemble that of any other protein in the database. The sequence upstream of the open reading frame shows typical characteristics of a promoter region with two overlapping, divergently orientated promoters.