Preferential repair of N-acetoxy-acetylaminofluorene lesions in the nuclease-hypersensitive region of simian virus 40

We exposed simian virus 40-infected CV-1 monkey cells to the carcinogen N-acetoxy-acetylaminofluorene and monitored the removal of lesions from cellular DNA and from various regions of viral DNA. Exposure to 5.5 microM 3H-labeled carcinogen produced 20-80 adducts per 10(6) bases in cellular DNA in different experiments. The initial adduct concentration in viral DNA was always approximately half that in cellular DNA. At various times after treatment, cellular and viral DNA, and restriction fragments of viral DNA, were purified and examined for adduct density. Independent of the initial adduct concentration three rates of repair were observed. Cellular DNA was repaired at the lowest rate. Viral DNA was repaired about 50% more rapidly than was cellular DNA isolated from the same carcinogen-treated monolayers. Within the viral DNA a 366-base pair region containing the major nuclease-hypersensitive site was repaired at twice the rate of the rest of the viral genome. This region contains regulatory sequences that govern the initiation of DNA replication and viral gene expression. As reported previously this region was initially modified 1.71 +/- 0.20-fold higher than expected from its guanine content. Selective repair diminished the extent of hypermodification of this region by 6.0 +/- 2.1% per hour, partly compensating for the higher initial level of adducts.     

Increased near-ultraviolet induced DNA fragmentation in xeroderma pigmentosum variants.

Immediate fragmentation of parental DNA by near-ultraviolet irradiation at 313 nm was measured in cultured skin fibroblasts from normal individuals, patients with Xeroderma pigmentosum of complementation group A (XPA) and Xeroderma pigmentosum variants (XPV) by the alkaline elution procedure. For a dose of 2.25 KJm^?2 given at O^o fragmentation was comparable in all cell strains. However, fragmentation was strongly increased relative to O^o in XPV but not in normal fibroblasts and the XPA strains when irradiation was carried out at 37^o. From our results it appears that a step in the repair of $\text{parental}$ DNA is abnormal in XPV.     

Daily Rhythms in Blood and Milk Lead Toxicokinetics Following Intravenous Administration of Lead Acetate to Dairy Cows in Winter

The objective was to investigate circadian variations of blood and milk lead toxicokinetics in dairy cows in winter. Twenty lactating Holstein animals were randomly assigned to 4 treatments, corresponding to different hours after onset of light (HALO): 2, 8, 14 and 20. Cows received a single intravenous administration of 2.5 mg/kg lead as lead acetate. Blood and milk samples were taken and analyzed by atomic absorption spectrophotometry. For each toxicokinetic parameter, a one-way analysis of variance was performed to outline the existence of daily variations. Significant differences as a function of HALO were detected in blood for the hybrid constant of elimination (β), half-life of elimination (t_1/2β), area under the curve (AUC) and clearance (Cl) (p &lt; 0.01) and volume of distribution at steady state (V_ss) (p < 0.05). Half-life of elimination was highest when lead acetatae was injected at 2 HALO, and lowest following the 14 HALO administration. Milk data showed significant differences for maximum concentration, AUC and Cl (p &lt; 0.001), volume of distribution and V_ss (p < 0.005). The ratio AUC_milk/ABC_blood was utilized to estimate penetration of lead in milk. It differed significantly along the day (p < 0.01). Blood daily variations could be fitted a circadian rhythms. No circadian rhythms were detected in milk parameters or in the ratio AUC_milk/ABC_blood. It was concluded that blood and milk lead toxicokinetics are distinctly affected by the time of the day.     

Histidine decarboxylase, DOPA decarboxylase, and vesicular monoamine transporter 2 expression in neuroendocrine tumors: immunohistochemical study and gene expression analysis.

Histidine decarboxylase (HDC) and vesicular monoamine transporter 2 (v-MAT2) are involved in the biosynthesis and storage of histamine. DOPA decarboxylase (DDC) is involved in the biosynthesis of a variety of amines and shares a high degree of homology with HDC. HDC and v-MAT2 immunoreactivities (IR) have recently been detected in well-differentiated neuroendocrine tumors (WDNETs) and poorly differentiated neuroendocrine carcinomas (PDNECs) of various sites and have been proposed as general endocrine markers. We evaluated HDC and v-MAT2 IR in a series of 117 WDNETs and PDNECs from different sites. Western blotting analysis was performed to verify the specificity of anti-DDC and anti-HDC antibodies. Real-time RT-PCR was performed using specific probes for HDC and DDC on 42 cases, examined also for DDC IR. HDC and v-MAT2 IR were observed in the majority of WDNETs and PDNECs of all sites and HDC-IR cases were always also DDC-IR. In contrast, high levels of HDC mRNA were detected only in the gastroenteropancreatic WDNETs, which did not show increased DDC mRNA levels. On the other hand, bronchial carcinoids and lung PDNECs showed high DDC mRNA levels, but nearly undetectable HDC mRNA levels. Western blotting analysis showed a cross-reaction between anti-HDC and anti-DDC antibodies. HDC should not be considered as a general endocrine marker and HDC IR in bronchial carcinoids and PDNECs of the lung can probably be attributed to a cross-reaction with DDC.     

Signal processing methods for information enhancement in atrial fibrillation: Spectral analysis and non-linear parameters

Recently, the research efforts in the context of electrocardiographical recording during atrial fibrillation (AF) has been directed to broaden the understandings on the electrophysiological and structural remodelling occurring during the arrhythmia and on characterizing the different types of AF. Following this line, both surface ECG and endocardial electrograms have been thoroughly studied and a series of linear and non-linear parameters were computed either directly on the electrograms or on the derived activation series.

In this paper, we reviewed some signal processing methods used to characterize surface ECG and endocardial electrograms during AF, focusing on spectral and non-linear analysis. In particular, parametric and non-parametric methods for spectral analysis of the residual ECG, i.e. atrial waves obtained from surface ECG after removing ventricular activity, and endocardial recordings are described. The different purposes of spectral analysis (exploring autonomic functions, analysis of spontaneous AF behaviour and predicting therapeutic effects) are illustrated with some examples. In addition, we described some more recent non-linear methods applied to AF, assessing the organization of atrial signals as well as ventricular response in AF. In particular, methods derived from embedding time series and based on entropy computation are illustrated and exemplified.     

Identification and functional expression of a second human beta-galactoside alpha2,6-sialyltransferase, ST6Gal II.

BLAST analysis of the human and mouse genome sequence databases using the sequence of the human CMP-sialic acid:beta-galactoside alpha-2,6-sialyltransferase cDNA (hST6Gal I, EC2.4.99.1) as a probe allowed us to identify a putative sialyltransferase gene on chromosome 2. The sequence of the corresponding cDNA was also found as an expressed sequence tag of human brain. This gene contained a 1590 bp open reading frame divided in five exons and the deduced amino-acid sequence didn't correspond to any sialyltransferase already known in other species. Multiple sequence alignment and subsequent phylogenic analysis showed that this new enzyme belonged to the ST6Gal subfamily and shared 48% identity with hST6Gal-I. Consequently, we named this new sialyltransferase ST6Gal II. A construction in pFlag vector transfected in COS-7 cells gave raise to a soluble active form of ST6Gal II. Enzymatic assays indicate that the best acceptor substrate of ST6Gal II was the free disaccharide Galbeta1-4GlcNAc structure whereas ST6Gal I preferred Galbeta1-4GlcNAc-R disaccharide sequence linked to a protein. The alpha2,6-linkage was confirmed by the increase of Sambucus nigra agglutinin-lectin binding to the cell surface of CHO transfected with the cDNA encoding ST6Gal II and by specific sialidases treatment. In addition, the ST6Gal II gene showed a very tissue specific pattern of expression because it was found essentially in brain whereas ST6Gal I gene is ubiquitously expressed.     

Impacts of the 2014–2017 global bleaching event on a protected remote atoll in the Western Indian Ocean

Coral Reefs - The third global bleaching event caused prolonged elevated sea surface temperatures from 2014 to 2017 that heavily impacted coral reefs worldwide. This study determines changes in...