A Unifying Organ Model of Pancreatic Insulin Secretion

The secretion of insulin by the pancreas has been the object of much attention over the past several decades. Insulin is known to be secreted by pancreatic β-cells in response to hyperglycemia: its blood concentrations however exhibit both high-frequency (period approx. 10 minutes) and low-frequency oscillations (period approx. 1.5 hours). Furthermore, characteristic insulin secretory response to challenge maneuvers have been described, such as frequency entrainment upon sinusoidal glycemic stimulation; substantial insulin peaks following minimal glucose administration; progressively strengthened insulin secretion response after repeated administration of the same amount of glucose; insulin and glucose characteristic curves after Intra-Venous administration of glucose boli in healthy and pre-diabetic subjects as well as in Type 2 Diabetes Mellitus. Previous modeling of β-cell physiology has been mainly directed to the intracellular chain of events giving rise to single-cell or cell-cluster hormone release oscillations, but the large size, long period and complex morphology of the diverse responses to whole-body glucose stimuli has not yet been coherently explained. Starting with the seminal work of Grodsky it was hypothesized that the population of pancreatic β-cells, possibly functionally aggregated in islets of Langerhans, could be viewed as a set of independent, similar, but not identical controllers (firing units) with distributed functional parameters. The present work shows how a single model based on a population of independent islet controllers can reproduce very closely a diverse array of actually observed experimental results, with the same set of working parameters. The model’s success in reproducing a diverse array of experiments implies that, in order to understand the macroscopic behaviour of the endocrine pancreas in regulating glycemia, there is no need to hypothesize intrapancreatic pacemakers, influences between different islets of Langerhans, glycolitic-induced oscillations or β-cell sensitivity to the rate of change of glycemia.     

Infarction Distribution Pattern in Acute Stroke May Predict the Extent of Leptomeningeal Collaterals

Objective

The aim of this study was to evaluate whether the distribution pattern of early ischemic changes in the initial MRI allows a practical method for estimating leptomeningeal collateralization in acute ischemic stroke (AIS).

Methods

Seventy-four patients with AIS underwent MRI followed by conventional angiogram and mechanical thrombectomy. Diffusion restriction in Diffusion weighted imaging (DWI) and correlated T2-hyperintensity of the infarct were retrospectively analyzed and subdivided in accordance with Alberta Stroke Program Early CT score (ASPECTS). Patients were angiographically graded in collateralization groups according to the method of Higashida, and dichotomized in 2 groups: 29 subjects with collateralization grade 3 or 4 (well-collateralized group) and 45 subjects with grade 1 or 2 (poorly-collateralized group). Individual ASPECTS areas were compared among the groups.

Results

Means for overall DWI-ASPECTS were 6.34 vs. 4.51 (well vs. poorly collateralized groups respectively), and for T2-ASPECTS 9.34 vs 8.96. A significant difference between groups was found for DWI-ASPECTS (p<0.001), but not for T2-ASPECTS (p = 0.088). Regarding the individual areas, only insula, M1-M4 and M6 showed significantly fewer infarctions in the well-collateralized group (p-values <0.001 to 0.015). 89% of patients in the well-collateralized group showed 0–2 infarctions in these six areas (44.8% with 0 infarctions), while 59.9% patients of the poor-collateralized group showed 3–6 infarctions.

Conclusion

Patients with poor leptomeningeal collateralization show more infarcts on the initial MRI, particularly in the ASPECTS areas M1 to M4, M6 and insula. Therefore DWI abnormalities in these areas may be a surrogate marker for poor leptomeningeal collaterals and may be useful for estimation of the collateral status in routine clinical evaluation.     

Changes in the proteome of Salmonella enterica serovar Thompson as stress adaptation to sublethal concentrations of thymol

Thymol is a natural biocide and component of some essential oils from herbs. Its inhibitory effect on the growth of different microorganisms is well documented. The precise targets of the antibacterial action of thymol is not yet been fully established, the action seems to take place in different ways. The strain Salmonella enterica serovar Thompson MCV1 was grown in the presence of a sublethal concentration (0.01%) of thymol. The proteins extracted from treated and untreated cells were subjected to 2‐D PAGE, followed by in‐gel spot digestion and subsequent MALDI‐TOF analysis. The analysis of gels showed many proteins that were either upregulated or downregulated by the presence of thymol, with significant changes in proteins belonging to different functional classes. In particular, the thioredoxin‐1 was not expressed in the treated cells, indicating that its absence could be a consequence of the stress caused by the presence of thymol. On the other hand, different chaperon proteins were upregulated or de novo synthesis such as GroEL and DnaK, key proteins in the protection mechanism toward thermal stress. Outer membrane proteins were upregulated in treated cells; indeed the bacterial envelope stress response is trigged by the accumulation of misfolded outer membrane proteins. Moreover, the thymol seems to impair the citrate metabolic pathway, as well as many enzymes involved in the synthesis of ATP. Definitely, thymol plays a role in altering very different pathways of cell metabolism.     

Hydroxyapatite affinity chromatography for the highly selective enrichment of mono‐ and multi‐phosphorylated peptides in phosphoproteome analysis

The most challenging analytical task facing phosphoproteome determination requires the isolation of phosphorylated peptides from the myriad of unphosphorylated species. In the past, several strategies for phosphopeptide isolation have been proposed in combination with subsequent mass spectrometric investigations. Among these techniques, immobilized metal affinity chromatography and titanium dioxide have been recognized as the most effective. Here, we present an alternative method for the enrichment of phosphopeptides based on hydroxyapatite (HAP) chromatography. By taking advantage of the strong interaction of HAP with phosphate and calcium ions, we developed an efficient method for the selective separation and fractionation of phosphorylated peptides. The effectiveness and efficiency of recovery for this procedure was assayed using tryptic digests of standard phosphorylated protein mixtures. Based on the higher affinity of multi‐phosphorylated peptides for HAP surfaces, the introduction of a phosphate buffer gradient for stepwise peptide elution resulted in the separation of mono‐, di‐, tri‐, and multi‐phosphorylated peptides. Thus, we demonstrated that this technique is highly selective and independent of the degree of peptide phosphorylation.     

Cats and Dogs Down the Tree: The Tempo and Mode of Evolution in the Lower Carnassial of Fossil and Living Carnivora

Teeth are usually considered the primer to understand mammalian evolution. Their morphology is the result of the complex interplay between adaptation to food processing and somewhat fixed developmental programs. We analyse the morphometry of the first lower molar (m1 = lower carnassial) in 199 carnivore species (64 extant and 135 extinct) in order to clarify the tempo and mode of evolution of two different and possibly related traits, tooth size and tooth angular height. We applied a set of comparative methods and produced disparity through time plots by using four alternative phylogenetic trees. Three of them include fossil species, and were used in order to estimate what an effect the inclusion of fossil species has on the patterns we found for extant species. Our analyses on living species show that m1 size exhibits a weak phylogenetic signal, and that its variance occurs more within than among clades. The opposite applies to m1 angular height, which evolved in an adaptive radiation-like fashion, showing very strong phylogenetic signal and great among-clade variation. These results are thoroughly confirmed after the inclusion of fossil data. Major differences in m1 shape in Carnivora were clearly established early in their evolutionary history, probably as a result of rapid morphospace occupation after the clade radiation. Successive variation in tooth size allowed species to avoid potential overlap in feeding morphologies as a mechanism to limit interspecific competitive interaction within subclades.     

Sites in the AAV5 capsid tolerant to deletions and tandem duplications

Gene therapy vectors based on adeno-associated virus (AAV) have shown much promise in clinical trials for the treatment of a variety of diseases. However, the ability to manipulate and engineer the viral surface for enhanced efficiency is necessary to overcome such barriers as pre-existing immunity and transduction of non-target cells that currently limit AAV applications. Although single amino acid changes and peptide insertions at select sites have been explored previously, the tolerance of AAV to small deletions and tandem duplications of sequence has not been globally addressed. Here, we have generated a large, diverse library of >10⁵ members containing deletions and tandem duplications throughout the viral capsid of AAV5. Four unique mutants were identified that maintain the ability to form viral particles, with one showing improved transduction on both 293T and BEAS-2B cells. This approach may find potential use for the generation of novel variants with improved and altered properties or in the identification of sites that are tolerant to insertions of targeting ligands.     

The use of nomegestrol acetate in rapid preparation of endometrium before operative hysteroscopy in pre-menopausal women

The presence of a thin endometrium has an important role in allowing the best conditions for hysteroscopic surgery. Here, we explored the efficacy of a 14-day administration of nomegestrol acetate, a progestogen with high progestogen potency effects, in rapid endometrial preparation to operative hysteroscopy.A total of 86 fertile women selected for operative hysteroscopy received for 14 days either 5 mg day⁻¹ of nomegestrol acetate (n = 43; group A) or 4 mg day⁻¹ of folic acid (n = 43; group B), starting on day 1 of the subsequent menstrual cycle. Before treatments on days 12-14 of the menstrual cycle, all patients underwent endometrial thickness measurement; ultrasonography of the ovaries to measure the appearance of a dominant follicle; diagnostic hysteroscopy with endometrial biopsy; plasma estradiol (E2), progesterone (P), luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels measurements. On the day of surgery, patients repeated endometrial and ovarian ultrasonography and, E2, P, LH and FSH measurement.At enrolment, endometrial thickness, mean follicular diameter and E2, P, LH and FSH concentrations did not differ between groups. At the time of operative hysteroscopy (i.e., after 14 days’ treatment) group A, but not group B, showed significant (all P < 0.001) reduction of endometrial thickness, mean diameter of dominant follicle, E2, P and LH concentrations. Endometrial preparation was judged more effective in group A than B, since the endometrial mucosa in all of the women of group A appeared to be very thin, hypotrophic, regular and pale. In conclusion, administration of nomegestrol acetate was effective in reducing endometrial thickness, also acting on the hypothalamus-pituitary-ovarian axis, thus allowing highly favourable operative hysteroscopic conditions.     

The tissue banking in cancer and stem cell research

The Sapio Award was established in 1999 by the Sapio Group along with several Italian universities and research centers to recognize Italian scientists who have made a major contribution to the discovery or development of novel technologies in the fields of biotechnology, social and health services, nonotechnology and biosecurity in agricultural production and scientific distribution. The 2006 edition of the award meeting centered around the issues of tissue banks and biorepositories and translational medicine. The organizing committee divided this edition into a pre-meeting held in Milan on October 18, 2006 and a master meeting on October 19, 2006, held at the ISS in Rome. A summary of these meetings is given.     

Speciation of phytate ion in aqueous solution. Protonation constants and copper(II) interactions in NaNO3aq at different ionic strengths

The acid base behavior of phytate has been studied (at t=25 degrees C by potentiometry, ISE-H+ glass electrode) in NaNO3aq at different ionic strengths (0.1 < or = I/mol L(-1) < or = 1.0). The interactions with copper(II) were investigated in the same experimental conditions in different metal to ligand (Phy) ratios (1:1 < or = Cu2+ :Phy < or = 4:1), by using both ISE-H+ and ISE-Cu2+ electrodes. Phytate acid base behavior in sodium nitrate is very similar to that in sodium chloride, previously investigated. In the experimental conditions adopted, the formation of three CuiHjPhy(12-2i-j)- species is observed: the mononuclear CuH4Phy6- and CuH5Phy5-, and the dinuclear Cu2H5Phy3-. Analysis of complex formation constants at different ionic strengths reveals that both ISE-H+ and ISE-Cu2+ electrodes gave, within the experimental error, analogous values. Dependence of complex formation constants on ionic strength was modeled by EDH (Extended Debye-Hückel) and SIT (Specific ion Interaction Theory) equations. The sequestering ability of phytate toward copper(II) has been evaluated by the calculation of pL50 (the total ligand concentration, as -log CL, able to bind 50% of metal cation), an empirical parameter already proposed for an objective "quantification" of this ability. A thorough analysis of literature data on phytate-copper(II) complexes has been performed.