Label-free detection of DNA single-base mismatches using a simple reflectance-based optical technique.

Rapid and quantitative detection of the binding of nucleic acids to surface-immobilized probes remains a challenge in many biomedical applications. We investigated the hybridization of a set of fully complementary and defected 12-base long DNA oligomers by using the Reflective Phantom Interface (RPI), a recently developed multiplexed label-free detection technique. Based on the simple measurement of reflected light intensity, this technology enables to quantify the hybridization directly as it occurs on the surface with a sensitivity of 10 pg mm(-2). We found a strong effect of single-base mismatches and of their location on hybridization kinetics and equilibrium binding. In line with previous studies, we found that DNA-DNA binding is weaker on a surface than in the bulk. Our data indicate that this effect is a consequence of weak nonspecific binding of the probes to the surface.

Design of a rapid, multiplex, one-pot miRNA assay optimized by label-free analysis.

MicroRNAs are widely studied as circulating biomarkers for early stage diagnosis of several diseases. Detection and quantification of miRNAs is currently performed through complex and time consuming procedures. Herein we demonstrate a rapid, multiplex, one-pot detection method based on two-step amplification of the signal measured by Reflective Phantom Interface (RPI) label-free optical biosensor. We achieved sub-pM quantification of different miRNAs in about 1.5 h, through specific capture with surface DNA probes combined to a 35-fold mass amplification by an antibody targeting DNA-RNA hybrids and polyclonal secondary antibody, all performed without washing steps. The assay is the result of a modelling and optimization of the multi-step process that has been made possible by the RPI characterization of each individual interaction involved.

Most Earth-surface calcites precipitate out of isotopic equilibrium.

Oxygen-isotope thermometry played a critical role in the rise of modern geochemistry and remains extensively used in (bio-)geoscience. Its theoretical foundations rest on the assumption that 18O/16O partitioning among water and carbonate minerals primarily reflects thermodynamic equilibrium. However, after decades of research, there is no consensus on the true equilibrium 18O/16O fractionation between calcite and water (18αcc/w). Here, we constrain the equilibrium relations linking temperature, 18αcc/w, and clumped isotopes (Δ47) based on the composition of extremely slow-growing calcites from Devils Hole and Laghetto Basso (Corchia Cave). Equilibrium 18αcc/w values are systematically ~1.5‰ greater than those in biogenic and synthetic calcite traditionally considered to approach oxygen-isotope equilibrium. We further demonstrate that subtle disequilibria also affect Δ47 in biogenic calcite. These observations provide evidence that most Earth-surface calcites fail to achieve isotopic equilibrium, highlighting the need to improve our quantitative understanding of non-equilibrium isotope fractionation effects instead of relying on phenomenological calibrations.

Enhanced climate instability in the North Atlantic and southern Europe during the Last Interglacial.

Considerable ambiguity remains over the extent and nature of millennial/centennial-scale climate instability during the Last Interglacial (LIG). Here we analyse marine and terrestrial proxies from a deep-sea sediment sequence on the Portuguese Margin and combine results with an intensively dated Italian speleothem record and climate-model experiments. The strongest expression of climate variability occurred during the transitions into and out of the LIG. Our records also document a series of multi-centennial intra-interglacial arid events in southern Europe, coherent with cold water-mass expansions in the North Atlantic. The spatial and temporal fingerprints of these changes indicate a reorganization of ocean surface circulation, consistent with low-intensity disruptions of the Atlantic meridional overturning circulation (AMOC). The amplitude of this LIG variability is greater than that observed in Holocene records. Episodic Greenland ice melt and runoff as a result of excess warmth may have contributed to AMOC weakening and increased climate instability throughout the LIG.

Optical and electro-optical derivation of the pretransitional behavior of orientational and shear viscosities in the isotropic phase of liquid crystals.

The pretransitional equilibrium properties of isotropic liquids in the proximity of the isotropic-nematic phase transition are well known and successfully modeled. Much less is known about the dynamic behavior, and in particular about the pretransitional viscosity. In this work we combine two techniques [dynamic light scattering (DLS) and electric birefringence spectroscopy (EBS)] offering complementary insights into both static and dynamic pretransitional behavior of the homologous nCB family (n-alkyl cyanobiphenyl). EBS explores the single molecule flipping dynamics retarded by a paranematic potential barrier and enables extracting the associated transport coefficient, which is found to be of Arrhenius type in the whole temperature range explored. DLS reflects the collective dynamics of correlated domains and depends on the viscous damping of the orientational order. Such a viscosity displays Arrhenius behavior only sufficiently far from the transition temperature, with deviations growing as a power law of the appropriate reduced temperature with exponents around 0.1.

Heterosexual transmission of the human immunodeficiency virus: a seroepidemiological study.

The transmission of the human immunodeficiency virus (HIV) was studied in 647 subjects who presented no apparent risk factors for the infection other than having had promiscuous heterosexual relations, heterosexual relations with people with an elevated risk of infection, or heterosexual relations with people infected by human immunodeficiency virus. Thirty subjects were found to be seropositive for anti-human immunodeficiency virus antibodies. The elevated risk factors included being the habitual partner of a person at risk of infection or of a person who was infected by human immunodeficiency virus, or being the partner of a patient with acquired immunodeficiency syndrome. The transmission of the virus was verified in 13 of 284 subjects (4.57%) who had had heterosexual intercourse three or more times with persons at risk and in 16 of 101 subjects (15.84%) who had had heterosexual intercourse three or more times with persons who were seropositive for human immunodeficiency virus antibodies. No significant correlation between human immunodeficiency virus infection and a history of sexually transmitted infections, nor between human immunodeficiency virus infection and female subjects was found. These data suggest that the epidemic of acquired immunodeficiency syndrome can also spread through heterosexual relations, even if the possibility of becoming infected in this way seems at the moment limited to particular risk behaviors.

Primary hepatic actinomycosis.

A case of primary hepatic actinomycosis is reported. Multiple liver abscesses were diagnosed in a febrile 60-year-old-man by means of non-invasive techniques such as ultrasonography, CT and radioisotope scans. The aetiology was confirmed by the unusual finding of Actinomyces israelii in anaerobic blood cultures. Other sites were not involved. Early penicillin therapy enabled surgery to be avoided.

[Tuberculous lymphadenitis. Apropos of a non-typical histological picture]. / Linfoadenite tubercolare. A proposito di un quadro istologico non tipico.

The case is presented of a young Somali with acute lymphadenitis. Whereas histological examination indicated abscessing granulomatous lymphadenitis, bacteriological studies revealed the presence of M. tuberculosis in the pus taken from the lymph node. Hence the aetiological diagnosis contradicted the morphological picture.

Stable isotope analysis of archaeological oak charcoal from eastern Anatolia as a marker of mid-Holocene climate change.

Comparison between modern trees and archaeological charred wood is an under-explored method to study climate change, which may help to infer past environmental changes. The stable carbon content of deciduous oak charcoals was analysed for five periods covering more than a 1000 years (3350-2000 BC) at the site of Arslantepe, Turkey, together with modern deciduous oak specimens from five rare arboreal patches still present in the area (17-64 km from the site). In studies of past climate change it is difficult to distinguish human-induced changes from independent variations, such as the impact of past populations on the landscape and their relationship with climate changes in the mid-Holocene. Archaeology can evaluate climate signals preserved in fossil plants in light of past human life. This paper will contribute to understanding environmental changes that can be attributed to climate variation and those linked to human activities. We compared (13) C/(12) C of modern and fossil oaks in order to correlate the (13) C-content to environmental features of Arslantepe, both today and between 3350 and 2000 BC. At present, this area is semi-arid. The results show important similarities to palaeoenvironmental records for the rest of the Near East. The climate trend can be divided in three main phases: instability phase from ca. 3200 to 2900 BC; a phase of relative stability (until 2350 BC); and a final increase in aridity. The comparison of Δ(13) C values between fossil and modern plants shows that present climate is more arid than that between the end of the fourth and the whole third millennium BC.

Evidence for obliquity forcing of glacial Termination II.

Variations in the intensity of high-latitude Northern Hemisphere summer insolation, driven largely by precession of the equinoxes, are widely thought to control the timing of Late Pleistocene glacial terminations. However, recently it has been suggested that changes in Earth's obliquity may be a more important mechanism. We present a new speleothem-based North Atlantic marine chronology that shows that the penultimate glacial termination (Termination II) commenced 141,000 +/- 2500 years before the present, too early to be explained by Northern Hemisphere summer insolation but consistent with changes in Earth's obliquity. Our record reveals that Terminations I and II are separated by three obliquity cycles and that they started at near-identical obliquity phases.

Liquid crystal alignment on a chiral surface: interfacial interaction with sheared DNA films.

We explore the alignment of various achiral liquid crystals on films of aligned double-stranded helical DNA. In all cases and both for the nematic and smectic A phases, we find a distinctly chiral interfacial structure, with the mean orientation of the liquid crystal in contact with the DNA-treated surfaces chirally rotated through a substantial angle with respect to the mean DNA orientation. This rotation originates in the chirality of double-stranded DNA and depends on the liquid crystal molecular structure. We discuss the role of dipolar and hydrophobic coupling in determining the observed orientation.

Amebic pleuro-pericarditis.

Author's report a case of visceral amebiasis in a 26 year old woman, clinically characterized by pericarditis, without any other symptoms related to organs usually interested in such disease. It was possible to reach an etiological diagnosis by indirect hemagglutination assay. The successful treatment with metronidazole confirmed the etiology "ex adjuvantibus".

[On a case of autochthonous amebiasis]. / Su un caso di amebiasi autoctona.

Amoebiasis is usually acquired in countries where the disease is endemic. A case is presented of hepatic infection acquired indigenously. The Authors emphasized the importance of amoebic hepatic abscess as potential cause for delay in diagnosis.

Behavior of antibody profile against hepatitis C virus in patients on maintenance hemodialysis.

The prevalence of anti-hepatitis C virus (HCV) in dialysis setting is still a nonstandard datum. In particular, it is not known of the phenomenon is stable or increasing or decreasing, even in a given geographical area. We studied the behavior of anti-HCV prevalence during a 12-month follow-up in 415 hemodialysis patients treated at a single institution and belonging to a limited geographical area with standard HCV endemic. Point prevalence of anti-HCV has shown a tendency to growth linked in part of the incidence of infection, in part to new positivities in patients already on dialysis treatment. More than 50% of the new HCV-positive patients, had no history of classical parenteral transmission of the virus. These findings suggest that HCV infection is a phenomenon on the increase in dialysis units and that dialysis treatment emerges as an independent risk factor in contracting infection.

[Description of a case of type E botulism in Italy]. / Descrizione di un caso di botulismo di tipo E in Italia.

The authors report the first documented italian case of type E botulism. The initial symptoms were typical permitting prompt diagnosis; the symptoms became severe and the patient had to be moved to intensive care. Biological tests on guinea-pigs showed the presence of type E botulin toxin in the tuna (stored in oil) which the patient had eaten 24 hours prior to admission. This tuna had been caught near the mediterranean coast of Spain several months earlier and canned at home. The authors emphasize that, even though this fish was imported, there is a danger that this intoxication could, in the future, be more widely observed.

Detection of serum HIV-Ag related to the major core protein (p24) in persons at risk for AIDS.

A commercial enzyme immunoassay was utilized for the detection of the human immunodeficiency virus antigen (p24) in serum samples from persons at risk for AIDS. The test demonstrated sensitivity to 20 pg/ml of serum antigen. The results obtained showed 14.63% of the subjects (Ss) with persistent generalized lymphadenopathy or asymptomatic Ss, and 69.23% of the Ss with AIDS related complex (ARC) or AIDS to be positive for HIV-Ag. In addition, there were no false-positives in the control serum samples collected from seronegative individual. The close correlation observed between HIV-Ag presence and advanced stages of the disease, stresses the diagnostic importance of this viral marker and its usefulness in the follow-up of Ss with HIV infection.