Subfractionation of cell populations by partitioning in dextran-poly (ethylene glycol) aqueous phases

Partitioning of cells in dextran-poly(ethylene glycol) aqueous two-phase systems depends on the interaction between the surface properties of the cells and the physical properties of the phases. The latter can be manipulated to a considerable extent by selection of polymer concentrations and ionic composition and concentration. If salts (e.g., phopshate) are used that have an unequal affinity for the two phases, an electrostatic potential difference between the phases results and, at appropriately high polymer concentrations, the partition coefficient of cells is determined predominantly by membrane charge-associated properties. By “balancing” the magnitude of the electrostatic potential difference against that of the interfacial tension (primarily a function of polymer, but also phosphate, concentrations) one can obtain phase systems that give usable partition coefficients for most cell populations (1). In work under way in our laboratory on the effects of different chemical and enzymatic modifications on the relative surface properties of rat red blood cells of different ages, we have now found that certain phase compositions did not resolve such treated cell subpopulations while other phase compositions did. Thus not all charged phase systems in which cell populations as a whole have usable partition coefficients are equally capable of detecting or subfractionating cell subpopulations. It is therefore essential, before drawing conclusions on the nonseqarability of cell subpopulations, to test cell separability in charged phase systems of different compositions if the system initially chosen does not afford a subfractionation.     

Meninigiomas of the Craniocervical Junction – A Distinctive Subgroup of Meningiomas

ObjectiveMeningioma of the cranio-cervical junction is a rare diagnosis and demand a thorough surgical planning as radical excision of these tumors is difficult. In this context recurrence is most likely due to regrowth of residual tumor. The aim of this study was to evaluate the clinical course of patients operated for craniocervical meningioma (CCM) and to investigate the histological features of these tumors and their impact on recurrence rate.MethodsAll patients who were operated for CCM at our institution between 2003 and 2012 were identified. Presenting symptoms, MRI findings, surgical approaches and recurrence rate were reviewed retrospectively using medical charts. Histological features of the included tumors were studied focusing on subtypes and MIB-1 immunoreactivity and compared with MIB-1 immunoreactivity in an age and gender-matched control group of patients with supratentorial meningioma.Results18 patients with CCM with a mean age of 56.2 years and median follow-up of 60 months were included in the study. Sensory or motor deficit was the most frequent presenting symptom followed by neck pain and lower cranial nerve palsy. Simpson grade II resection was achieved in 16 patients and Simpson grade III resection in two patients. Mortality, morbidity and recurrence rates were 16.7%, 5.5% and 5.5%, respectively. According to the WHO-grading all were found to be grade I meningiomas. Histological subtypes included meningotheliomatous (10), transitional (2), fibrillar (2), angiomatous (3) and secretory (1) meningioma. The mean MIB-1 labeling index in the study group was significantly higher than in the control group, (7.2% and 3.6%, respectively), p < 0.05. There was no correlation between MIB-1 levels and tumor recurrence.ConclusionsCCM seems to have a benign character. Despite a significantly higher MIB-1 index, a high rate of recurrence was not observed. Therefore, approaches with high morbidity are not justified. Nevertheless, in view of the challenging approaches with limited access to the lesion, CCM should be considered a distinctive clinical subgroup.     

Effect of Acute Exercise on Prostate Cancer Cell Growth

Physical activity is associated with reduced risk of several cancers, including aggressive prostate cancer. The mechanisms mediating the effects are not yet understood; among the candidates are modifications of endogenous hormone levels. Long-term exercise is known to reduce serum levels of growth stimulating hormones. In contrast, the endocrine effects of acute endurance exercise include increased levels of mitogenic factors such as GH and IGF-1. It can be speculated that the elevation of serum growth factors may be detrimental to prostate cancer progression into malignancy. The incentive of the current study is to evaluate the effect of acute exercise serum on prostate cancer cell growth. We designed an exercise intervention where 10 male individuals performed 60 minutes of bicycle exercise at increasing intensity. Serum samples were obtained before (rest serum) and after completed exercise (exercise serum). The established prostate cancer cell line LNCaP was exposed to exercise or rest serum. Exercise serum from 9 out of 10 individuals had a growth inhibitory effect on LNCaP cells. Incubation with pooled exercise serum resulted in a 31% inhibition of LNCaP growth and pre-incubation before subcutaneous injection into SCID mice caused a delay in tumor formation. Serum analyses indicated two possible candidates for the effect; increased levels of IGFBP-1 and reduced levels of EGF. In conclusion, despite the fear of possible detrimental effects of acute exercise serum on tumor cell growth, we show that even the short-term effects seem to add to the overall beneficial influence of exercise on neoplasia.     

Local climatic adaptation in a widespread microorganism

Exploring the ability of organisms to locally adapt is critical for determining the outcome of rapid climate changes, yet few studies have addressed this question in microorganisms. We investigated the role of a heterogeneous climate on adaptation of North American populations of the wild yeast Saccharomyces paradoxus. We found abundant among-strain variation for fitness components across a range of temperatures, but this variation was only partially explained by climatic variation in the distribution area. Most of fitness variation was explained by the divergence of genetically distinct groups, distributed along a north–south cline, suggesting that these groups have adapted to distinct climatic conditions. Within-group fitness components were correlated with climatic conditions, illustrating that even ubiquitous microorganisms locally adapt and harbour standing genetic variation for climate-related traits. Our results suggest that global climatic changes could lead to adaptation to new conditions within groups, or changes in their geographical distributions.     

Green Manure and Overlapped Rhizosphere Effects on Pb Chemical Forms in Soil and Plant Uptake in Maize/Canola Intercrop Systems: A Rhizobox Study

To investigate the effects of single and mixed cultures of maize and canola, green manure addition, and distance from the rhizosphere on chemical forms of soil lead (Pb) and its uptake by plants, a greenhouse experiment was conducted using rhizobox systems. After plant harvest, the soils from different parts of the rhizoboxes were sampled and analyzed for dissolved organic carbon (DOC) concentrations and pH values. A sequential extraction procedure was also carried out to differentiate the chemical forms of Pb in the soil samples. Results showed that root activity significantly affected soil DOC concentration, pH and Pb chemical forms, while the effects generally ceased from the rhizosphere through the bulk soil. The pH value increased and DOC concentration decreased with distance from the roots. Green manure addition enhanced DOC concentration and exchangeable, carbonate-associated, and organic matter-bound Pb fractions. Green manure addition reduced the Pb concentration and uptake of maize but increased those of canola. The concentration of Pb in the roots of maize and canola was increased in intercropping compared with monocropping systems. The conclusion is that chemistry and bioavailability of soil Pb are interactively influenced by overlapped rhizospheres as compared to individual rhizospheres, use of green manure, and distance from the root surfaces.     

Methane, a gas produced by enteric bacteria, slows intestinal transit and augments small intestinal contractile activity

The presence of methane on lactulose breath test among irritable bowel syndrome (IBS) subjects is highly associated with the constipation-predominant form. Therefore, we set out to determine whether methane gas can alter small intestinal motor function. In dogs, small intestinal fistulae were created to permit measurement of intestinal transit. Using a radiolabel, we evaluated transit during infusion of room air and subsequently methane. In this model, small intestinal infusion of methane produced a slowing of transit in all dogs by an average of 59%. In a second experiment, guinea pig ileum was pinned into an organ bath for the study of contractile activity in response to brush strokes applied to the mucosa. The force of contraction was measured both orad and aborad to the stimulus. The experiment was repeated while the bath was gassed with methane. Contractile activities orad and aborad to the stimulus were significantly augmented by methane compared with room air (P < 0.05). In a third experiment, humans with IBS who had undergone a small bowel motility study were compared such that subjects who produced methane on lactulose breath test were compared with those producing hydrogen. The motility index was significantly higher in methane-producing IBS patients (1,851 +/- 861) compared with hydrogen producers (1,199 +/- 301) (P < 0.05). Therefore, methane, a gaseous by-product of intestinal bacteria, slows small intestinal transit and appears to do so by augmenting small bowel contractile activity.     

Tumor cell-derived exosomes: A message in a bottle

Exosomes constitute the newest mode of intercellular communication, transmitting information between cells. This exchange of molecular information is facilitated by their unique composition which is enriched with enzymes, structural proteins, adhesion molecules, lipid rafts and RNAs. Following the discovery that cancer cells secrete excessive amounts of exosomes compared to normal cells, it became evident that i) these vesicles can be used as diagnostic markers; ii) their active secretion has functional implications, albeit unknown whether they are tumor promoting or suppressing. Notably, the interplay via the exchange of exosomes between cancer cells and between cancer cells and the tumor stroma may promote the transfer of oncogenes (e.g. β-catenin, CEA, HER2, Melan-A/Mart-1 and LMP-1) and onco-microRNAs (e.g. let7, miR1, miR15, miR16 and miR375) from one cell to another, leading to the reprogramming of the recipient cells. The molecular composition and functional role of tumor cell-derived exosomes in tumorigenesis, metastasis and response to therapy are slowly decrypted and the latest findings as well as potential therapeutic strategies are discussed in this review.     

Plant virus infection modifies plant pigment and manipulates the host preference behavior of an insect vector

Insect-borne plant viruses may modify the phenotype of their host plants and thus influence the responses of insect vectors. When a plant virus modifies host preference behavior of a vector, it can be expected to influence the rate of virus transmission. In this study, we examined the effect of Maize Iranian mosaic virus (MIMV) infection on host preference behavior of the nymphs and adults of its vector, the small brown planthopper, Laodelphax striatellus Fallén (Hemiptera: Delphacidae), feeding on barley plants (Hordeum vulgare L., Poaceae). We found that both viruliferous nymphs and adults significantly preferred healthy plants, whereas non-viruliferous planthoppers preferred virus-infected barley. Further investigations revealed significant reductions in the chlorophyll and carotenoid contents of infected barley leaves. Based on these results, a possible association between insect host preferences and the pigment contents of the plants was observed. In summary, we suggest that host preference of L. striatellus could be affected by the propagative plant virus, possibly through association of this modification with some phenotypic traits of infected plants. These effects may have a critical impact on MIMV transmission rate, with significant implications for the development of virus epidemics.