Germline variants in oculocutaneous albinism genes and predisposition to familial cutaneous melanoma

Approximately 1%–2% of cutaneous melanoma (CM) is classified as strongly familial. We sought to investigate unexplained CM predisposition in families negative for the known susceptibility genes using next‐generation sequencing of affected individuals. Segregation of germline variants of interest within families was assessed by Sanger sequencing. Several heterozygous variants in oculocutaneous albinism (OCA) genes: TYR, OCA2, TYRP1 and SLC45A2, were present in our CM cohort. OCA is a group of autosomal recessive genetic disorders, resulting in pigmentation defects of the eyes, hair and skin. Missense variants classified as pathogenic for OCA were present in multiple families and some fully segregated with CM. The functionally compromised TYR p.T373K variant was present in three unrelated families. In OCA2, known pathogenic variants: p.V443I and p.N489D, were present in three families and one family, respectively. We identified a likely pathogenic SLC45A2 frameshift variant that fully segregated with CM in a family of four cases. Another four‐case family harboured cosegregating variants (p.A24T and p.R153C) of uncertain functional significance in TYRP1. We conclude that rare, heterozygous variants in OCA genes confer moderate risk for CM.     

Mapping changes to vegetation pattern in a restoring wetland: Finding pattern metrics that are consistent across spatial scale and time

Tidal salt marshes in the San Francisco Estuary region display heterogeneous vegetation patterns that influence wetland function and provide adequate habitat for native or endangered wildlife. In addition to analyzing the extent of vegetation, monitoring the dynamics of vegetation pattern within restoring wetlands can offer valuable information about the restoration process. Pattern metrics, derived from classified remotely sensed imagery, have been used to measure composition and configuration of patches and landscapes, but they can be unpredictable across scales, and inconsistent across time. We sought to identify pattern metrics that are consistent across spatial scale and time – and thus robust measures of vegetation and habitat configuration – for a restored tidal marsh in the San Francisco Bay, CA, USA. We used high-resolution (20 cm) remotely sensed color infrared imagery to map vegetation pattern over 2 years, and performed a multi-scale analysis of derived vegetation pattern metrics. We looked at the influence on metrics of changes in grain size through resampling and changes in minimum mapping unit (MMU) through smoothing. We examined composition, complexity, connectivity and heterogeneity metrics, focusing on perennial pickleweed (Sarcocornia pacifica), a dominant marsh plant. At our site, pickleweed patches grew larger, more irregularly shaped, and closely spaced over time, while the overall landscape became more diverse. Of the two scale factors examined, grain size was more consistent than MMU in terms of identifying relative change in composition and configuration of wetland marsh vegetation over time. Most metrics exhibited unstable behavior with larger MMUs. With small MMUs, most metrics were consistent across grain sizes, from fine (e.g. 0.16 m²) to relatively large (e.g. 16 m²) pixel sizes. Scale relationships were more variable at the landcover class level than at the landscape level (across all classes). This information may be useful to applied restoration practitioners, and adds to our general understanding of vegetation change in a restoring marsh.     

Phosphatidylinositol 3-kinase-dependent,MEK- independent proliferation in response to CaR activation

Although ovarian surface epithelial(OSE) cells are responsible for the majority of ovarian tumors, we knowrelatively little about the pathway(s) that is responsible forregulating their proliferation. We found that phosphatidylinositol3-kinase (PI3K) is activated in OSE cells in response to elevatedextracellular calcium, and the PI3K inhibitors wortmannin and LY-294002inhibited extracellular signal-regulated kinase (ERK) activation by~75%, similar to effects of the mitogen-activated protein kinase/ERK kinase inhibitor PD-98059. However, in assays of proliferation, we found that PD-98059 inhibited proliferation by ~50%, whereas wortmannin inhibited >90% of the proliferative response to elevated calcium. Expression of a dominant negative PI3K totally inhibited ERKactivation in response to calcium. These results demonstrate that ERKactivation cannot account for the full proliferative effect of elevatedcalcium in OSE cells and suggest the presence of an ERK-independent,PI3K-dependent component in the proliferative response.

     

Switching the mode of metabolism in the yeast Saccharomyces cerevisiae

The biochemistry of most metabolic pathways is conserved from bacteria to humans, although the control mechanisms are adapted to the needs of each cell type. Oxygen depletion commonly controls the switch from respiration to fermentation. However, Saccharomyces cerevisiae also controls that switch in response to the external glucose level. We have generated an S. cerevisiae strain in which glucose uptake is dependent on a chimeric hexose transporter mediating reduced sugar uptake. This strain shows a fully respiratory metabolism also at high glucose levels as seen for aerobic organisms, and switches to fermentation only when oxygen is lacking. These observations illustrate that manipulating a single step can alter the mode of metabolism. The novel yeast strain is an excellent tool to study the mechanisms underlying glucose-induced signal transduction.     

Cytokine gene polymorphisms in endemic pemphigus foliaceus: a possible role for IL6 variants

Endemic pemphigus foliaceus (EPF) is a complex autoimmune disease characterized by the presence of antibodies against desmoglein 1, which lead to the loss of adhesion among keratinocytes (acantholysis). Variants of HLA class II genes have been the only genetic factors found to modulate susceptibility to EPF. This study aims at investigating the influence of cytokine genetic variants in the pathogenesis of EPF, since they may affect the expression levels of these immunomodulatory molecules. The sample included 168 patients and 189 controls and was comprised of mostly Caucasoids and Mulattos. The approach consisted of a case-control association study and the alleles were identified by mismatched PCR-RFLP. No associations were found with variants of IL1A, IL1B, IL1RN, IL4R and IL10. There was a weak negative association with the haplotype -1082G -592C (OR=0.49) of the IL10 gene in Mulattos. In regard to polymorphism -590 of the IL4 gene, a positive association with the T/T genotype (OR=2.71) and a negative association with the C variant (OR=0.37) were found. Associations with IL6 -174 variants suggest that the C/C genotype has a protective effect (OR=0.13) while carriers of the G allele are more susceptible (OR=7.66) to EPF.     

Dynamic light scattering and fluorescence study of the interaction between double-stranded DNA and poly(amido amine) dendrimers

The interaction between a cationic poly(amido amine) (PAMAM) dendrimer of generation 4 and double-stranded salmon sperm DNA in 10 mM NaBr solution has been investigated using dynamic light scattering (DLS) and steady-state fluorescence spectroscopy. The structural parameters of the formed aggregates as well as the complex formation process were studied in dilute solutions. When DNA is mixed with PAMAM dendrimers, it undergoes a transition from a semiflexible coil to a more compact conformation due to the electrostatic interaction present between the cationic dendrimer and the anionic polyelectrolyte. The DLS results reveal that one salmon sperm DNA molecule forms a discrete aggregate in dilute solution with several PAMAM dendrimers with a mean apparent hydrodynamic radius of 50 nm. These discrete complexes coexist with free DNA at low molar ratios of dendrimer to DNA, which shows that cooperativity is present in the complex formation. The formation of the complexes was confirmed by agarose gel electrophoresis measurements. DNA in the complexes was also found to be significantly more protected against DNase catalyzed digestion compared to free DNA. The number of dendrimers per DNA chain in the complexes was found to be approximately 35 as determined by steady-state fluorescence spectroscopy.     

Flux of sterol intermediates in a yeast strain deleted of the lanosterol C-14 demethylase Erg11p

Lanosterol C-14 demethylase Erg11p of the yeast Saccharomyces cerevisiae catalyzes the enzymatic step following formation of lanosterol by the lanosterol synthase Erg7p in lipid particles (LP). Localization experiments employing microscopic inspection and cell fractionation revealed that Erg11p in contrast to Erg7p is associated with the endoplasmic reticulum (ER). An erg11Delta mutation in erg3Delta background, which is required to circumvent lethality of the erg11 defect, did not only change the sterol pattern but also the sterol distribution within the cell. Whereas in wild type the plasma membrane was highly enriched in ergosterol and LP harbored large amounts of sterol precursors in the form of steryl esters, sterol intermediates were more or less evenly distributed among organelles of erg11Delta erg3Delta. This distribution is not result of the erg3Delta background, because in the erg3Delta strain the major intermediate formed, ergosta-7,22-dienol, is also highly enriched in the plasma membrane similar to ergosterol in wild type. These results indicate that (i) exit of lanosterol from LP occurs independently of functional Erg11p, (ii) random supply of sterol intermediates to all organelles of erg11Delta erg3Delta appears to compensate for the lack of ergosterol in this mutant, and (iii) preferential sorting of ergosterol in wild type, but also of ergosta-7,22-dienol in erg3Delta, supplies sterol to the plasma membrane.     

Predictors of post-stroke body temperature elevation

Background

Growing evidence indicates that elevated body temperature after stroke is associated with unfavorable outcome. The aim of the current study was to investigate which factors predict temperature elevation within 48 h of stroke onset. Specifically, we hypothesized that temperature elevation would be associated with stroke symptom severity and that hemorrhagic stroke would cause a more pronounced temperature increase compared to ischemic stroke.

Methods

The medical records of 400 stroke patients were retrospectively reviewed. Multiple linear regression analysis was used to determine which factors were associated with elevated body temperature.

Results

Several factors were significantly associated with peak body temperature (the highest recorded body temperature) within 48 h of stroke onset: stroke severity measured by the National Institutes of Health Stroke Scale (NIHSS) (regression coefficient; (RC) 0.022), female gender (RC 0.157), tympanic/non-rectal temperature reading (RC ?0.265), swallowing difficulties (RC 0.335), intubation (RC 0.470), antipyretic treatment (RC 0.563), and C-reactive protein?>?50 or signs of infection at admission (RC 0.298). Contrary to our expectations, patients with intracerebral hemorrhage did not have higher peak body temperatures than patients with ischemic stroke.

Conclusions

In conclusion, temperature elevation within the first 48 h of stroke onset is common, can be partially predicted using information at admission and is strongly associated with stroke severity. The strong association with stroke severity may, at least partly, explain the previously described association between post-stroke temperature elevation and unfavorable outcome.