Nuclear fragmentation and DNA degradation during programmed cell death in petals of morning glory (Ipomoea nil)

We studied DNA degradation and nuclear fragmentation during programmed cell death (PCD) in petals of Ipomoea nil (L.) Roth flowers. The DNA degradation, as observed on agarose gels, showed a large increase. Using DAPI, which stains DNA, and flow cytometry for DAPI fluorescence, we found that the number of DNA masses per petal at least doubled. This indicated chromatin fragmentation, either inside or outside the nucleus. Staining with the cationic lipophilic fluoroprobe DiOC6 indicated that each DNA mass had an external membrane. Fluorescence microscopy of the nuclei and DNA masses revealed an initial decrease in diameter together with chromatin condensation. The diameters of these condensed nuclei were about 70% of original. Two populations of nuclear diameter, one with an average diameter about half of the other, were observed at initial stages of nuclear fragmentation. The diameter of the DNA masses then gradually decreased further. The smallest observed DNA masses had a diameter less than 10% of that of the original nucleus. Cycloheximide treatment arrested the cytometrically determined changes in DNA fluorescence, indicating protein synthesis requirement. Ethylene inhibitors (AVG and 1-MCP) had no effect on the cytometrically determined DNA changes, suggesting that these processes are not controlled by endogenous ethylene

Immunocytochemical expression of p16 INK4A and Ki-67 in cytologically negative and equivocal pap smears positive for oncogenic human papillomavirus

This study was designed to analyze the cross-sectional comparison of the p16 INK4A and Ki-67 immunocytochemical expression in negative and equivocal (atyp-ical squamous cells of undetermined significance (ASC-US)) liquid-based cytology (LBC) samples testing positive for high-risk human papillomavirus (HPV) types with HC2 assay or polymerase-chain reaction (PCR). A series of 199 consecutive LBC speci-mens derived from the same number of women participating in the ongoing Latin American Screening Study at Leonor Mendes de Barros Hospital, São Paulo, were analyzed using immunocytochemistry for expression of p16 INK4A and Ki-67 in negative and equivocal LBC samples testing positive for high-risk HPV types with hybrid capture II test (HC2) or PCR. All patients with at least one test positive (cytology, PCR, and/or HC2) were followed each 6 months for 3 years. The follow-up procedure consisted of visual examination, colposcopic inspection, cytology, and HC2 assay. Among the neg-ative cytologic samples, 101 were HPV-positive and 55 HPV-negative. Of the HPV-pos-itive group, 59 of 101 cases (58.4%) were positive for both p16 and Ki67 immunostaining, and 17 of 101 (16.8%) were negative for both. The proportion of Ki-67-positivity increased almost in parallel with the increasing grade of p16-positivity (p = 0.0001 for linear trend). In the HPV-negative group, both markers were negative in 41 of 55 cases (74.5%), and no statistical relationship was observed between the two markers (Pearson, p = 0.595). HPV-positive ASC-US samples demonstrated a simulta-neous positive immunoreaction for p16 and Ki67 in 11 of 16 cases (68.7%), whereas 3 (18.7%) were concurrently negative. The relationship between the two markers was of borderline significance (Pearson, p = 0.053), but no linear relationship was found be-tween the graded p16 and Ki-67 expression (p = 0.065 for linear trend). In the HPV-negative ASC-US group, there was no statistical association between the graded p16 and Ki-67 positivity (Pearson, p = 0.281). After 36 months of follow-up of the ASC-US patients, 6 women still displayed ASC-US smear, of which 4 of 6 were HPV-positive and expressed both p16 and Ki-67 markers. Two of 43 ASC-US smears had high-grade squamous intraepithelial lesions diagnosed (4.6%), and 1 had low-grade squamous intraepithelial lesion (2.3%). All of those were positive for HPV, p16 and Ki-67. Patients with ASC-US diagnosis and positive high-risk HPV status and positive for p16 INK4A Ki67 should be carefully observed to exclude occurrence of a squamous intraepithelial lesion. The combination of these two markers can be a useful implement for manage-ment of women with equivocal cytology.European Commission (EC) - INCO-DEV Programme - Project #ICA4-CT-2001-10013

Prognostic significance of microvessel density and other variables in Japanese and British patients with primary invasive breast cancer

The purpose of this study is to investigate the associations of microvessel density (MVD) and other pathological variables with survival, and whether they accounted for survival differences between Japanese and British patients. One hundred seventy-three Japanese and 184 British patients were included in the study. British patients were significantly older (56.3±11.4 years vs 52.5±12.9 years; P<0.01) and had smaller tumours (2.2±1.3 vs 2.7±1.8 cm; P<0.01), which were more frequently oestrogen receptor positive (78.8 vs 57.2%, P<0.01), had more grade III tumours (29.9 vs 21.4%, P=0.04) and more infiltrating lobular carcinomas (13.6 vs 4.0%, P<0.01) and a higher MVD compared with Japanese patients (57.9±19.8 vs 53.2±18.6; P=0.01). However, no difference in the prevalence of lymph-node metastasis was found between them (39.1 vs 37.5%, P=0.75). Younger British patients (age <50 years) had the highest MVD compared with Japanese and older British patients (P<0.01). Japanese patients were proportionately more likely to receive chemotherapy than endocrine therapy (P<0.01). British patients had a significantly worse relapse-free survival and overall survival compared with Japanese patients, after statistical adjustment for variables (hazard ratio=2.1, 2.4, P<0.01, P<0.01, respectively), especially, in T2 stage, low MVD and older subgroup (HR: 3.6, 5.0; 3.1, 3.3; 3.2, 3.9, respectively), but only in ER negative cases (P=0.04, P=0.01, respectively). The present study shows that MVD contributes to the Japanese–British disparity in breast cancer. However, the MVD variability did not explain the survival differences between Japanese and British patients

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong