Tuning the photophysical features of self-assembling photoactive polypeptides for light-harvesting

The LH1 complex is the major light-harvesting antenna of purple photosynthetic bacteria. Its role is to capture photons, and then store them and transfer the excitation energy to the photosynthetic reaction center. The structure of LH1 is modular and it cooperatively self-assembles from the subunits composed of short transmembrane polypeptides that reversibly bind the photoactive cofactors: bacteriochlorophyll and carotenoid. LH1 assembly, the intra-complex interactions and the light-harvesting features of LH1 can be controlled in micellar media by varying the surfactant concentration and by adding carotenoid and/or a co-solvent. By exploiting this approach, we can manipulate the size of the assembly, the intensity of light absorption, and the energy and lifetime of its first excited singlet state. For instance, via the introduction of Ni-substituted bacteriochlorophyll into LH1, the lifetime of this electronic state of the antenna can be shortened by almost three orders of magnitude. On the other hand, via the exchange of carotenoid, light absorption in the visible range can be tuned. These results show how in a relatively simple self-assembling pigment-polypeptide system a sophisticated functional tuning can be achieved and thus they provide guidelines for the construction of bio-inspired photoactive nanodevices

Dopaminergic Regulation of Circadian Food Anticipatory Activity Rhythms in the Rat

Circadian activity rhythms are jointly controlled by a master pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) and by food-entrainable circadian oscillators (FEOs) located elsewhere. The SCN mediates synchrony to daily light-dark cycles, whereas FEOs generate activity rhythms synchronized with regular daily mealtimes. The location of FEOs generating food anticipation rhythms, and the pathways that entrain these FEOs, remain to be clarified. To gain insight into entrainment pathways, we developed a protocol for measuring phase shifts of anticipatory activity rhythms in response to pharmacological probes. We used this protocol to examine a role for dopamine signaling in the timing of circadian food anticipation. To generate a stable food anticipation rhythm, rats were fed 3h/day beginning 6-h after lights-on or in constant light for at least 3 weeks. Rats then received the D2 agonist quinpirole (1 mg/kg IP) alone or after pretreatment with the dopamine synthesis inhibitor α-methylparatyrosine (AMPT). By comparison with vehicle injections, quinpirole administered 1-h before lights-off (19h before mealtime) induced a phase delay of activity onset prior to the next meal. Delay shifts were larger in rats pretreated with AMPT, and smaller following quinpirole administered 4-h after lights-on. A significant shift was not observed in response to the D1 agonist SKF81297. These results provide evidence that signaling at D2 receptors is involved in phase control of FEOs responsible for circadian food anticipatory rhythms in rats

Dopant Concentration Induced Optical Changes in Ca, Eu-α-Sialon

The phosphor powders of Ca(m/2)–xEuxSi12–(m+n)Alm+nOnN16–n (m = 1.6, n = 0.8, x in the range of 0–0.08) were synthesized by means of a solid state reaction in flowing nitrogen in a carbon resistant furnace and the influence of Eu concentration on the crystal structure and photoluminescent properties was thoroughly studied. The optical properties of selected α-sialon:Eu2+ samples at temperatures in the range of 10 to 500 K and pressures up to 240 kbar are presented. The crystal lattice parameters were affected by doping with europium and some increase of the unit cell volume was observed up to 6 mol % of Eu. The higher concentration of europium led to subtle changes in the overall structure of the produced sialon phosphors. It was shown that the chemical composition of Ca, Eu-α-sialon phosphor was slightly different from the designed one and the phosphor powders were contaminated by AlN. The phosphor particle surface showed significant europium and oxygen enrichment with Eu3+ but below the thin surface layer Eu2+ was dominant and higher nitrogen content was observed. After examination of absorption, excitation, and emission spectra it was found that the emission peak position shifted toward longer wavelengths with rising Eu2+ concentration from 565 nm (0.1 mol % Eu2+) to 585 nm (10 mol % Eu2+). The quantum yield of the phosphors reached the maximum at a rather low concentration of 4 mol % of Eu. Excitation spectra depend on the monitored wavelength which is typical for multisite Eu2+. The existence of many Eu2+ sites in the sample was supported by the dependence of the decay time on the monitored wavelength

Midday Meals Do Not Impair Mouse Memory

Nocturnal mice fed in the middle of the light period exhibit food anticipatory rhythms of behavior and physiology under control of food-entrainable circadian clocks in the brain and body. This is presumed to be adaptive by aligning behavior and physiology with predictable mealtimes. This assumption is challenged by a report that daytime feeding schedules impair cognitive processes important for survival, including object memory and contextual fear conditioning assessed at two times of day. To further evaluate these effects, mice were restricted to a 6 h daily meal in the middle of the light or dark period and object memory was tested at four times of day. Object memory was not impaired by daytime feeding, and did not exhibit circadian variation in either group. To determine whether impairment might depend on methodology, experimental procedures used previously to detect impairment were followed. Daytime feeding induced food anticipatory rhythms and shifted hippocampal clock genes, but again did not impair object memory. Spontaneous alternation and contextual fear conditioning were also not impaired. Hippocampal memory function appears more robust to time of day and daytime feeding schedules than previously reported; day-fed mice can remember what they have seen, where they have been, and where it is dangerous

Management of melanoma metastases in the brain

The basic principle for the diagnosis of melanoma metastases in the brain should be the management of multidisciplinary teams including at least a neurosurgeon, radiotherapist and clinical oncologist experienced in the treatment of melanoma and melanoma metastases in the CNS. Detection of brain lesions is associated with poor prognosis; metastases in the brain are the cause of death in 20–50% patients, and symptomatic tumours are a direct cause of death in about 90% patients. Treatment of melanoma with CNS metastases may include local management and/or systemic and symptomatic treat­ment. In the last 5 years, 10 new advanced melanoma drugs have been registered in Europe. Two-drug therapy anti-PD-1 and anti-CTLA-4 (nivolumab with ipilimumab) is the treatment of choice for asymptomatic melanoma metastases in the brain, while in the presence of BRAF mutations and asymptomatic metastases systemic treatment with BRAFi and MEKi may be the first-choice treatment

Postępowanie w przerzutach czerniaka do mózgowia

Czerniak stanowi trzeci po raku piersi i płuca nowotwór złośliwy pod względem częstości występowania przerzutów do mózgowia. Aktualnie coraz częściej przerzuty do mózgowia diagnozuje się na etapie bezobjawowym, w badaniach obrazowych wykonywanych w ramach kontroli lub kwalifikacji chorego do leczenia systemowego. Leczenie chorych na czerniaka z przerzutami do mózgowia stanowi jedno z największych wyzwań w opiece nad chorym na czerniaka w stadium zaawansowanym. Celem niniejszego opracowania jest przedstawienie wielospecjalistycznych wskazówek co do postępowania diagnostyczno-terapeutycznego w tej grupie chorych. Leczenie chorych na czerniaka z przerzutami do mózgowia obejmuje w zależności od sytuacji klinicznej leczenie miejscowe i/lub leczenie systemowe oraz leczenie objawowe. Decyzje terapeutyczne powinny być podejmowane w zespołach, w skład których powinni wchodzić co najmniej onkolog kliniczny, neurochirurg i radioterapeuta

Foetal macrosomia — incidence, determinants and neonatal outcomes: 10-years retrospective review, 2010–2019

Objectives: Prevalence of macrosomia differs worldwide according to studied population and has been variable over last few decades. The objective of the study was to determine the trends in incidence and clinical characteristics of infants with macrosomia born in two diverse Polish neonatal centres from 2010–2019. Material and methods: Trends in the incidence of macrosomia, maternal age, delivery mode and neonatal complications were analysed over a 10 year period based on birth medical records. Results: The total number of 43 165 term neonates were analysed with macrosomia incidence of 16.63% (n = 7179). The prevalence of macrosomia was stable from 2010–2019 irrespectively of referentiality and geographical area. Mean maternal age increased over the decade with higher age of mothers of macrosomic neonates. Recognizability of gestation diabetes among pregnant women increased from 9.61% in 2010 to 15.27% in 2019 and it was comparable in mothers of macrosomic infants. The percentage of caesarean sections was higher in macrosomic neonates and gradually increased over last decade. The highest percentage of birth injuries was observed in the first grade of macrosomia (4000–4499 g). The number of neonatal complications including lower Apgar score, respiratory and cardiology symptoms correlated with severity of macrosomia, with highest morbidity in children above 5000 g. Conclusions: The prevalence of macrosomia in the studied cohort remained invariable over the last decade. Macrosomia is associated with an increased rate of caesarean sections, higher maternal age and increased neonatal morbidity. A higher macrosomia grade is related to a worse neonatal outcome. Further studies on other risk factors of macrosomia are needed