Durable memories and efficient neural coding through mnemonic training using the method of loci.

Mnemonic techniques, such as the method of loci, can powerfully boost memory. We compared memory athletes ranked among the world's top 50 in memory sports to mnemonics-naïve controls. In a second study, participants completed a 6-week memory training, working memory training, or no intervention. Behaviorally, memory training enhanced durable, longer-lasting memories. Functional magnetic resonance imaging during encoding and recognition revealed task-based activation decreases in lateral prefrontal, as well as in parahippocampal and retrosplenial cortices in both memory athletes and participants after memory training, partly associated with better performance after 4 months. This was complemented by hippocampal-neocortical coupling during consolidation, which was stronger the more durable memories participants formed. Our findings advance knowledge on how mnemonic training boosts durable memory formation through decreased task-based activation and increased consolidation thereafter. This is in line with conceptual accounts of neural efficiency and highlights a complex interplay of neural processes critical for extraordinary memory.

2D:4D and spatial abilities: From rats to humans.

Variance in spatial abilities are thought to be determined by in utero levels of testosterone and oestrogen, measurable in adults by the length ratio of the 2nd and 4th digit (2D:4D). We confirmed the relationship between 2D:4D and spatial performance using rats in two different tasks (paired-associate task and watermaze) and replicated this in humans. We further clarified anatomical and functional brain correlates of the association between 2D:4D and spatial performance in humans.

Ghrelin modulates encoding-related brain function without enhancing memory formation in humans.

Ghrelin regulates energy homeostasis in various species and enhances memory in rodent models. In humans, the role of ghrelin in cognitive processes has yet to be characterized. Here we show in a double-blind randomized crossover design that acute administration of ghrelin alters encoding-related brain activity, however does not enhance memory formation in humans. Twenty-one healthy young male participants had to memorize food- and non-food-related words presented on a background of a virtual navigational route while undergoing fMRI recordings. After acute ghrelin administration, we observed decreased post-encoding resting state fMRI connectivity between the caudate nucleus and the insula, amygdala, and orbitofrontal cortex. In addition, brain activity related to subsequent memory performance was modulated by ghrelin. On the next day, however, no differences were found in free word recall or cued location-word association recall between conditions; and ghrelin's effects on brain activity or functional connectivity were unrelated to memory performance. Further, ghrelin had no effect on a cognitive test battery comprising tests for working memory, fluid reasoning, creativity, mental speed, and attention. In conclusion, in contrast to studies with animal models, we did not find any evidence for the potential of ghrelin acting as a short-term cognitive enhancer in humans.

Production of ω-hydroxy octanoic acid with Escherichia coli.

The present proof-of-concept study reports the construction of a whole-cell biocatalyst for the de novo production of ω-hydroxy octanoic acid. This was achieved by hijacking the natural fatty acid cycle and subsequent hydroxylation using a specific monooxygenase without the need for the additional feed of alkene-like precursors. For this, we used the model organism Escherichia coli and increased primarily the release of the octanoic acid precursors by overexpressing the plant thioesterase FatB2 from Cuphea hookeriana in a ß-oxidation deficient strain, which lead to the production of 2.32mM (8.38mggcww(-1)) octanoic acid in 24h. In order to produce the corresponding ω-hydroxy derivative, we additionally expressed the engineered self-sufficient monooxygenase fusion protein CYP153AMaq(G307A)-CPRBM3 within the octanoic acid producing strain. With this, we finally produced 234µM (0.95mggcww(-1)) ω-hydroxy octanoic acid in a 20h fed-batch set-up.

Whole-cell microtiter plate screening assay for terminal hydroxylation of fatty acids by P450s.

A readily available galactose oxidase (GOase) variant was used to develop a whole cell screening assay. This endpoint detection system was applied in a proof-of-concept approach by screening a focussed mutant library. This led to the discovery of the thus far most active P450 Marinobacter aquaeolei mutant catalysing the terminal hydroxylation of fatty acids.

The role of rapid eye movement sleep for amygdala-related memory processing.

Over the years, rapid eye movement (REM) sleep has been associated with general memory consolidation, specific consolidation of perceptual, procedural, emotional and fear memories, brain maturation and preparation of waking consciousness. More recently, some of these associations (e.g., general and procedural memory consolidation) have been shown to be unlikely, while others (e.g., brain maturation and consciousness) remain inconclusive. In this review, we argue that both behavioral and neurophysiological evidence supports a role of REM sleep for amygdala-related memory processing: the amygdala-hippocampus-medial prefrontal cortex network involved in emotional processing, fear memory and valence consolidation shows strongest activity during REM sleep, in contrast to the hippocampus-medial prefrontal cortex only network which is more active during non-REM sleep. However, more research is needed to fully understand the mechanisms.

Enzyme engineering in the context of novel pathways and products.

In recent years, enzyme engineering was used to fine-tune a diverse set of proteins to realize new biosynthetic pathways and gain access to novel products. However, enzymes in nature do not always meet the required demands in terms of activity, selectivity and stability. In these cases enzyme engineering has been used to improve the enzyme properties, which facilitated the development of tailor-made functional biocatalysts, even beyond their natural capabilities. Examples can be found in the three main areas of chemical biotechnology: single-step biocatalysis, metabolic engineering and enzymatic cascades. In this review we highlight recently published work in all of these three fields and emphasize the main trends and differences.

[Mild whole body hyperthermia in combination with inpatient multimodal oriented pain therapy: evaluation in patients with chronic unspecific lumbar back pain]. / Milde Ganzkörperhyperthermie in Kombination mit stationärer multimodal orientierter Schmerztherapie: Evaluation bei Patienten mit chronischem unspezifischem lumbalem Rückenschmerz.

PURPOSE: A randomized controlled clinical trial was implemented to evaluate the effectiveness of combined mild hyperthermia therapy (body core temperature 38.4 °C) and multimodal inpatient rehabilitation for patients suffering from chronic low back pain when compared to multimodal pain therapy alone. PATIENTS AND METHODS: A total of 88 patients were randomly assigned to the combined or single therapeutic schemes according to a block randomization scheme. According to the trial inclusion criteria all patients suffered from chronic low back pain and showed morphological degeneration. All patients underwent a 12-day inpatient multimodal pain therapy, which was complemented with a 6-session schedule of mild hyperthermia therapy for the intervention group (1 h at 38.6 °C). On admission and 3 months after treatment the study patients were asked to complete an interview assessment with the Oswestry low back pain disability questionnaire (Oswestry disability index). The change in the Oswestry disability index total score (%) 3 months after versus before therapy was defined as the primary clinical endpoint of the investigation. The patients in the control group and in the intervention group had a median age of 50 years. In the intervention group 70 % of the patients were female and 55 % reported having half to full time employment compared to 55 % and 43 % in the control group, respectively. RESULTS: On admission the control patients reported a median Oswestry disability index of 64 % and on recall the same of 64 %. The intervention group showed median Oswestry disability index estimates of 60 % and 66 %, respectively. The changes in the overall Oswestry disability index after 3 months differed significantly with an estimated 6 % for the intervention group versus 0 % for the control group (Wilcoxon p = 0.050). CONCLUSION: When combined with a multimodal inpatient lower back pain functional therapy in patients showing morphological degeneration, the mild hyperthermia therapy demonstrated statistically significant, although not clinically relevant benefits in comparison to the multimodal treatment alone. However, regarding the moderate overall patient-related benefits as measured in terms of the Oswestry disability index, the benefit of the underlying multimodal therapy concept implementation must be critically discussed irrespective of its combination with mild hyperthermia therapy.

Exposure of clinical MRSA heterogeneous strains to ß-lactams redirects metabolism to optimize energy production through the TCA cycle.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as one of the most important pathogens both in health care and community-onset infections. The prerequisite for methicillin resistance is mecA, which encodes a ß-lactam-insensitive penicillin binding protein PBP2a. A characteristic of MRSA strains from hospital and community associated infections is their heterogeneous expression of resistance to ß-lactam (HeR) in which only a small portion (≤ 0.1%) of the population expresses resistance to oxacillin (OXA) ≥ 10 µg/ml, while in other isolates, most of the population expresses resistance to a high level (homotypic resistance, HoR). The mechanism associated with heterogeneous expression requires both increase expression of mecA and a mutational event that involved the triggering of a ß-lactam-mediated SOS response and related lexA and recA genes. In the present study we investigated the cellular physiology of HeR-MRSA strains during the process of ß-lactam-mediated HeR/HoR selection at sub-inhibitory concentrations by using a combinatorial approach of microarray analyses and global biochemical profiling employing gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) to investigate changes in metabolic pathways and the metabolome associated with ß-lactam-mediated HeR/HoR selection in clinically relevant heterogeneous MRSA. We found unique features present in the oxacillin-selected SA13011-HoR derivative when compared to the corresponding SA13011-HeR parental strain that included significant increases in tricarboxyl citric acid (TCA) cycle intermediates and a concomitant decrease in fermentative pathways. Inactivation of the TCA cycle enzyme cis-aconitase gene in the SA13011-HeR strain abolished ß-lactam-mediated HeR/HoR selection demonstrating the significance of altered TCA cycle activity during the HeR/HoR selection. These results provide evidence of both the metabolic cost and the adaptation that HeR-MRSA clinical strains undergo when exposed to ß-lactam pressure, indicating that the energy production is redirected to supply the cell wall synthesis/metabolism, which in turn contributes to the survival response in the presence of ß-lactam antibiotics.

Synthesis of 9-oxononanoic acid, a precursor for biopolymers.

Polymers based on renewable resources have become increasingly important. The natural functionalization of fats and oils enables an easy access to interesting monomeric building blocks, which in turn transform the derivative biopolymers into high-performance materials. Unfortunately, interesting building blocks of medium-chain length are difficult to obtain by traditional chemical means. Herein, a biotechnological pathway is established that could provide an environmentally suitable and sustainable alternative. A multiple enzyme two-step one-pot process efficiently catalyzed by a coupled 9S-lipoxygenase (St-LOX1, Solanum tuberosum) and 9/13-hydroperoxide lyase (Cm-9/13HPL, Cucumis melo) cascade reaction is proposed as a potential route for the conversion of linoleic acid into 9-oxononanoic acid, which is a precursor for biopolymers. Lipoxygenase catalyzes the insertion of oxygen into linoleic acid through a radical mechanism to give 9S-hydroperoxy-octadecadienoic acid (9S-HPODE) as a cascade intermediate, which is subsequently cleaved by the action of Cm-9/13HPL. This one-pot process afforded a yield of 73 % combined with high selectivity. The best reaction performance was achieved when lipoxygenase and hydroperoxide lyase were applied in a successive rather than a simultaneous manner. Green leaf volatiles, which are desired flavor and fragrance products, are formed as by-products in this reaction cascade. Furthermore, we have investigated the enantioselectivity of 9/13-HPLs, which exhibited a strong preference for 9S-HPODE over 9R-HPODE.

Targeting of PBP1 by ß-lactams determines recA/SOS response activation in heterogeneous MRSA clinical strains.

The SOS response, a conserved regulatory network in bacteria that is induced in response to DNA damage, has been shown to be associated with the emergence of resistance to antibiotics. Previously, we demonstrated that heterogeneous (HeR) MRSA strains, when exposed to sub-inhibitory concentrations of oxacillin, were able to express a homogeneous high level of resistance (HoR). Moreover, we showed that oxacillin appeared to be the triggering factor of a ß-lactam-mediated SOS response through lexA/recA regulators, responsible for an increased mutation rate and selection of a HoR derivative. In this work, we demonstrated, by selectively exposing to ß-lactam and non-ß-lactam cell wall inhibitors, that PBP1 plays a critical role in SOS-mediated recA activation and HeR-HoR selection. Functional analysis of PBP1 using an inducible PBP1-specific antisense construct showed that PBP1 depletion abolished both ß-lactam-induced recA expression/activation and increased mutation rates during HeR/HoR selection. Furthermore, based on the observation that HeR/HoR selection is accompanied by compensatory increases in the expression of PBP1,-2, -2a, and -4, our study provides evidence that a combination of agents simultaneously targeting PBP1 and either PBP2 or PBP2a showed both in-vitro and in-vivo efficacy, thereby representing a therapeutic option for the treatment of highly resistant HoR-MRSA strains. The information gathered from these studies contributes to our understanding of ß-lactam-mediated HeR/HoR selection and provides new insights, based on ß-lactam synergistic combinations, that mitigate drug resistance for the treatment of MRSA infections.

ß-Lactams increase the antibacterial activity of daptomycin against clinical methicillin-resistant Staphylococcus aureus strains and prevent selection of daptomycin-resistant derivatives.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged to be one of the most important pathogens both in health care and in community-onset infections. Daptomycin (DAP) is a cyclic anionic lipopeptide recommended for treatment of skin infections, bacteremia, and right-sided endocarditis caused by MRSA. Resistance to DAP (DAP(r)) has been reported in MRSA and is mostly accompanied by a parallel decrease in oxacillin resistance, a process known as the "seesaw effect." Our study provides evidence that the seesaw effect applies to other ß-lactams and carbapenems of clinical use, including nafcillin (NAF), cefotaxime (CTX), amoxicillin-clavulanic (AMC), and imipenem (IMP), in heterogeneous DAP(r) MRSA strains but not in MRSA strains expressing homogeneous ß-lactam resistance. The antibacterial efficacy of DAP in combination with ß-lactams was evaluated in isogenic DAP-susceptible (DAP(s))/Dap(r) MRSA strains originally obtained from patients that failed DAP monotherapy. Both in vitro (MIC, synergy-kill curve) and in vivo (wax worm model) approaches were used. In these models, DAP and a ß-lactam proved to be highly synergistic against both heterogeneous and homogeneous clinical DAP(r) MRSA strains. Mechanistically, ß-lactams induced a reduction in the cell net positive surface charge, reverting the increased repulsion provoked by DAP alone, an effect that may favor the binding of DAP to the cell surface. The ease of in vitro mutant selection was observed when DAP(s) MRSA strains were exposed to DAP. Importantly, the combination of DAP and a ß-lactam prevented the selection of DAP(r) variants. In summary, our data show that the DAP-ß-lactam combination may significantly enhance both the in vitro and in vivo efficacy of anti-MRSA therapeutic options against DAP(r) MRSA infections and represent an option in preventing DAP(r) selection in persistent or refractory MRSA infections.

VraSR two-component regulatory system contributes to mprF-mediated decreased susceptibility to daptomycin in in vivo-selected clinical strains of methicillin-resistant Staphylococcus aureus.

Daptomycin (DAP) is a new class of cyclic lipopeptide antibiotic highly active against methicillin-resistant Staphylococcus aureus (MRSA) infections. Proposed mechanisms involve disruption of the functional integrity of the bacterial membrane in a Ca-dependent manner. In the present work, we investigated the molecular basis of DAP resistance in a group of isogenic MRSA clinical strains obtained from patients with S. aureus infections after treatment with DAP. Different point mutations were found in the mprF gene in DAP-resistant (DR) strains. Investigation of the mprF L826F mutation in DR strains was accomplished by inactivation and transcomplementation of either full-length wild-type or mutated mprF in DAP-susceptible (DS) strains, revealing that they were mechanistically linked to the DR phenotype. However, our data suggested that mprF was not the only factor determining the resistance to DAP. Differential gene expression analysis showed upregulation of the two-component regulatory system vraSR. Inactivation of vraSR resulted in increased DAP susceptibility, while complementation of vraSR mutant strains restored DAP resistance to levels comparable to those observed in the corresponding DR wild-type strain. Electron microscopy analysis showed a thicker cell wall in DR CB5012 than DS CB5011, an effect that was related to the impact of vraSR and mprF mutations in the cell wall. Moreover, overexpression of vraSR in DS strains resulted in both increased resistance to DAP and decreased resistance to oxacillin, similar to the phenotype observed in DR strains. These results support the suggestion that, in addition to mutations in mprF, vraSR contributes to DAP resistance in the present group of clinical strains.

Fate of mutation rate depends on agr locus expression during oxacillin-mediated heterogeneous-homogeneous selection in methicillin-resistant Staphylococcus aureus clinical strains.

Methicillin-resistant Staphylococcus aureus (MRSA) strains are characterized by a heterogeneous expression of resistance. We have previously shown in clinical oxacillin-susceptible, mecA-positive MRSA strains that selection from a very heterogeneous (HeR) to highly homogeneous (HoR) resistant phenotype was mediated by acquisition of mutations through an oxacillin-induced SOS response. In the present study, we used a spotted DNA microarray to evaluate differential gene expression during HeR-HoR selection and found increased expression of the agr two-component regulatory system. We hypothesized that increased expression of agr represents a mechanistically relevant component of this process. We demonstrated that inactivation of agr during the HeR-HoR selection process results in a significant increase in mutation rate; these effects were reversed by complementing the agr mutant. Furthermore, we found that extemporal ectopic expression of agr and, more specifically, RNAII in agr-null mutant HeR cells suppressed mutation frequency and the capacity of these cells to undergo the HeR-HoR selection. These findings sustain the concept that increased expression of agr during HeR-HoR selection plays a critical role in regulating the ß-lactam-induced increased mutation rate in very heterogeneous MRSA strains. Moreover, they indicate that a temporally controlled increase in agr expression is required to tightly modulate SOS-mediated mutation rates, which then allows for full expression of oxacillin homogeneous resistance in very heterogeneous clinical MRSA strains.

Risk factors for mortality-morbidity after emergency-urgent colorectal surgery.

BACKGROUND: The aim of this study was to assess the risk factors associated with mortality and morbidity following emergency or urgent colorectal surgery. MATERIALS AND METHODS: All data regarding the 462 patients who underwent emergency colonic resection in our institution between November 2002 and December 2007 were prospectively entered into a computerized database. RESULTS: The median age of patients was 73 (range 17-98) years. The most common indications for surgery were: 171 adenocarcinomas (37%), 129 complicated diverticulitis (28%), and 35 colonic ischemia (7.5%). Overall mortality and morbidity rates were 14% and 36%, respectively. In multivariate analysis, the only parameter significantly associated with postoperative mortality was blood loss >500 cm(3) (odds ratio (OR) = 3.33, 95% confidence interval (CI) 1.63-6.82, p = 0.001). There were three parameters which correlated with postoperative morbidity: ASA score > or =3 (OR = 2.9, 95% CI 1.9-4.5, p < 0.001), colonic ischemia (OR = 3.4, 95% CI 1.4-7.7, p = 0.006), and stoma creation (OR = 2.2, 95% CI 1.4-3.4, p = 0.0003). CONCLUSIONS: The main risk factors for postoperative morbidity and mortality following emergency colorectal surgery are related to: (1) patients' ASA score, (2) colonic ischemia, and (3) perioperative bleeding. These variables should be considered in the elaboration of future scoring systems to predict outcome of emergency colorectal surgery.

Dysembryoplastic neuroepithelial micro-tumor in a 75-year-old patient with long-standing epilepsy.

Dysembryoplastic neuroepithelial tumors (DNT) are rare, cortically located neoplasma associated with intractable partial complex seizures. This entity was first described by Daumas-Duport et al. [1988], who also coined the term DNT. In that report, at the time of operation, the patients' ages ranged from 3 to 30 years and the duration of symptoms ranged from 2 to 18 years. In contrast, we observed a histologically comparable tumor in a 75-year-old female with a 60 year epilepsy history. Autopsy revealed an 8 mm large tumor in the right hippocampus. In view of the extremely prolonged course of the patient's symptoms and the complete lack of excessive cell proliferation, the differentiation of a genuine tumor versus a hamartoma remains equivocal.

Antiimmunoglobulins of rheumatoid factor (RF) type in prediction of melanoma patients.

It was found out the titer of antiimmunoglobulins of the rheumatoid factor (RF) type in the sera of melanoma patients can be used in prediction of the development of the patients' status. High titers of antiimmunoglobulins of the RF type, determined by the latex-fixation test (LFT), indicate an unfavorable prognosis in patients with clinical manifestation of uncontrollable recurrence appearing from 1.5 to 2 years after occurrence of the LFT titer.