Synaptic-dependent developmental dysconnectivity in 22q11.2 deletion syndrome.

Chromosome 22q11.2 deletion is among the strongest known genetic risk factors for neuropsychiatric disorders, including autism and schizophrenia. Brain imaging studies have reported disrupted large-scale functional connectivity in people with 22q11 deletion syndrome (22q11DS). However, the significance and biological determinants of these functional alterations remain unclear. Here, we use a cross-species design to investigate the developmental trajectory and neural underpinnings of brain dysconnectivity in 22q11DS. We find that LgDel mice, an established mouse model of 22q11DS, exhibit age-specific patterns of functional MRI (fMRI) dysconnectivity, with widespread fMRI hyper-connectivity in juvenile mice reverting to focal hippocampal hypoconnectivity over puberty. These fMRI connectivity alterations are mirrored by co-occurring developmental alterations in dendritic spine density, and are both transiently normalized by developmental GSK3ß inhibition, suggesting a synaptic origin for this phenomenon. Notably, analogous hyper- to hypoconnectivity reconfiguration occurs also in human 22q11DS, where it affects hippocampal and cortical regions spatially enriched for synaptic genes that interact with GSK3ß, and autism-relevant transcripts. Functional dysconnectivity in somatomotor components of this network is predictive of age-dependent social alterations in 22q11.2 deletion carriers. Taken together, these findings suggest that synaptic-related mechanisms underlie developmentally mediated functional dysconnectivity in 22q11DS.

Social modulation of on-screen looking behaviour.

While passive social information (e.g. pictures of people) routinely draws one's eyes, our willingness to look at live others is more nuanced. People tend not to stare at strangers and will modify their gaze behaviour to avoid sending undesirable social signals; yet they often continue to monitor others covertly "out of the corner of their eyes." What this means for looks that are being made near to live others is unknown. Will the eyes be drawn towards the other person, or pushed away? We evaluate changes in two elements of gaze control: image-independent principles guiding how people look (e.g. biases to make eye movements along the cardinal directions) and image-dependent principles guiding what people look at (e.g. a preference for meaningful content within a scene). Participants were asked to freely view semantically unstructured (fractals) and semantically structured (rotated landscape) images, half of which were located in the space near to a live other. We found that eye movements were horizontally displaced away from a visible other starting at 1032 ms after stimulus onset when fractals but not landscapes were viewed. We suggest that the avoidance of looking towards live others extends to the near space around them, at least in the absence of semantically meaningful gaze targets.

Clinical predictors and microbiology of ventilator-associated pneumonia in the intensive care unit: a retrospective analysis in six Italian hospitals.

The purpose of this study was to assess the main clinical predictors and microbiological features of ventilator-associated pneumonia (VAP) in the Intensive Care Unit (ICU) environment. This work is a retrospective analysis over one year from September 2010 to September 2011. Patients' risk factors, causes of admission, comorbidities and respiratory specimens collected in six Italian ICUs were reviewed. Incidence and case fatality rate of VAP were evaluated. After stratification for VAP development, univariate and multivariate analyses were performed to assess the impact of patients' conditions on the onset of this infection. A total of 1,647 ICU patients (pts) were considered. Overall, 115 patients (6.9 %) experienced at least one episode of VAP. The incidence rate for VAP was 5.82/1,000 pts-days, with a case fatality rate of 44.3 %. Multivariate analysis showed that admission for neurological disorders (aIRR 4.12, CI 1.24-13.68, p = 0.02) and emergency referral to ICU from other hospitals (aIRR 2.11, CI 1.03-4.31, p = 0.04) were associated with higher risk of VAP, whereas a tendency to a higher risk of infection was detected for admission due to respiratory disease, cardiac disease, trauma and for having obesity or renal failure. A total of 372 microbiological isolates from respiratory specimens were collected in VAP patients. The most common species were Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa, showing high resistance rates to carbapenems. Neurological disorders and emergency referral at the admission into the ICU are significantly associated with the onset of VAP. A high incidence of multi-drug resistant Gram- species was detected in the respiratory specimens.

The regional distribution of adenosine-regulating enzymes in the left and right ventricle walls of control and hypertrophic heart.

The transmural distribution of the adenosine-generating enzyme 5'-nucleotidase (5'N) and of the adenosine-degrading enzymes adenosine deaminase (ADA), AMP deaminase (AMP-D) and adenosine kinase (Ado-K) were determined across the walls of left and right ventricles of control and hypertrophic rat hearts. The enzyme distribution across the left ventricle wall (but not across the right wall) of normal hearts was not uniform: 5'N activity shows its highest levels in the subepicardial and in the subendocardial regions, whereas all the other enzyme activities show their lowest levels. A similar pattern of transmural distribution was also detected in other mammalian species (ox and pig). In the experimental cardiac hypertrophy, caused by two different types of chronic cardiac overload, the levels and the profiles of transmural distribution of 5'N and ADA enzyme activities may significantly change across the rat left ventricle wall.

Isoenzymes of phosphoglucomutase from human red blood cells: isolation and kinetic properties.

A procedure has been developed for the purification of phosphoglucomutase from human red cell (phenotype PGM1 a1 or a3) lysates. It yields homogeneous isoenzyme preparations of the products ("primary" and "secondary") of the two PGM1 and PGM2 loci with distinctive pI (from 6.07 to 5.29). There are substantial differences between PGM1 and PGM2 isoenzymes, having single polypeptide chains of 58,500 and 69,000 Mr respectively and showing different thermostability. The kinetic properties of all the isoenzymes for the phosphoglucomutase reaction are essentially the same (apart from the specific activity of 1089-1263 units/mg for PGM1 forms vs 37-42 units/mg for PGM2 forms), but there are striking differences in substrate specificity. In fact the products of PGM1 locus are "true" phosphoglucomutases, being specific to mutate glucose monophosphates, whereas the PGM2 forms also display phosphoribomutase and glucose 1,6-bisphosphate synthetic activities. Some kinetic properties of these "side activities" are also reported.

Phosphorylase-mediated mobilization of the amino group of adenine in Bacillus cereus.

Mobilization of the ribose moiety of purine nucleosides as well as of the amino group of adenine may be realized in Bacillus cereus by the concerted action of three enzymes: adenosine phosphorylase, adenosine deaminase, and purine nucleoside phosphorylase. In this pathway, ribose-1-phosphate and inorganic phosphate act catalytically, being continuously regenerated by purine nucleoside phosphorylase and adenosine phosphorylase, respectively. As a result of such a metabolic pathway, adenine is quantitatively converted into hypoxanthine, thus overcoming the lack of adenase in B. cereus.

Radioenzymatic determination of adenosine.

Adenosine has been measured at the nanomolar level by an enzymatic radioactive assay. The nucleoside is converted into [U-14C]ribose-labeled inosine via the following reactions: adenosine + H2O----adenine + ribose (adenosine nucleosidase); adenine + [U-14C]ribose 1-phosphate in equilibrium with T[U-14C]ribose-adenosine + Pi (adenosine phosphorylase); [U-14C]ribose-adenosine + H2O----[U-14C]ribose-inosine + NH3 (adenosine deaminase). The radioactivity of inosine, separated by thin-layer chromatography, is a measure of the adenosine initially present.

Studies on IMP degradation and ribose 1-phosphate utilization in human erythrocytes.

1. Intact human red cells do not attack exogenous IMP. The nucleotide is readily broken down by the soluble erythrocyte fraction to inosine, hypoxanthine and ribose 1-phosphate, with a pH optimum of approx. 6.2. 2. Ribose 1-phosphate can be actively reutilized, in the presence of ATP and hypoxanthine, to give IMP, at pH 7.4. The velocity of the IMP salvage synthesis dramatically increases at more alkaline pH values. 3. The two curves relating the velocities of IMP breakdown and of IMP synthesis as a function of hydrogen ion concentration intersect at pH 7.4. 4. The observations might be relevant in the process of purine transport by red cells.

In situ stability of uridylyl removing-uridylyltransferase of Escherichia coli.

The difference in sensitivity of UR/UT toward Lubrol WX permeabilization treatment of stationary phase E. coli cells is not uniquely related to nitrogen availability during cellular growth. The sensitivity of UR/UT to detergent treatment appears to be related to differences in the balance between fermentative and oxidative glucose metabolism. The possible occurrence of a third cycle in the glutamine synthetase regulatory cascade mechanism is considered.

In vitro 5-phosphoribosyl 1-pyrophosphate-independent salvage biosynthesis of ribo- and deoxyriboadenine nucleotides in Bacillus cereus.

The pools of free ribose 1-phosphate and deoxyribose 1-phosphate have been measured in Bacillus cereus. It is shown that crude extracts of the same organism can actively utilize the sugar phosphates to convert adenine to ATP and deoxyATP, via a 'salvage' pathway, involving adenine ribosylation (or deoxyribosylation), followed by multiple phosphorylation steps. The biosynthetic pathway operates even in the presence of excess P(i') thus showing that purine nucleoside phosphorylases may function in vivo, contrary to what is generally assumed, as anabolic rather than catabolic enzymes.

Growth conditions and inactivation of the uridylylation cycle of the glutamine synthetase regulatory system in permeabilized cells of E. coli.

The specific inactivation of the uridylylation cycle of glutamine synthetase regulatory system occurring when E. coliW grown with limited nitrogen supply is subjected to permeabilization by Lubrol WX, is not strictly related to the nitrogen starvation at cell harvesting. Evidences indicating that the sensitivity of uridylylremoving-uridylyltransferase enzyme complex to detergent treatment is affected by both rate of growth and cellular yield of the culture, are presented.