CaMKII autophosphorylation can occur between holoenzymes without subunit exchange

The dodecameric protein kinase CaMKII is expressed throughout the body. The alpha isoform is responsible for synaptic plasticity and participates in memory through its phosphorylation of synaptic proteins. Its elaborate subunit organization and propensity for autophosphorylation allow it to preserve neuronal plasticity across space and time. The prevailing hypothesis for the spread of CaMKII activity, involving shuffling of subunits between activated and naive holoenzymes, is broadly termed subunit exchange. In contrast to the expectations of previous work, we found little evidence for subunit exchange upon activation, and no effect of restraining subunits to their parent holoenzymes. Rather, mass photometry, crosslinking mass spectrometry, single molecule TIRF microscopy and biochemical assays identify inter-holoenzyme phosphorylation (IHP) as the mechanism for spreading phosphorylation. The transient, activity-dependent formation of groups of holoenzymes is well suited to the speed of neuronal activity. Our results place fundamental limits on the activation mechanism of this kinase.

Deformed wing virus of honey bees is inactivated by cold plasma ionized hydrogen peroxide

Deformed wing virus (DWV) is a widespread pathogen of Apis mellifera honey bees, and is considered a major causative factor for the collapse of infected honey bee colonies. DWV can be horizontally transmitted among bees through various oral routes, including via food sharing and by interactions of bees with viral-contaminated solid hive substrates. Cold plasma ionized hydrogen peroxide (iHP) is used extensively by the food production, processing and medical industries to clean surfaces of microbial contaminants. In this study, we investigated the use of iHP to inactivate DWV particles in situ on a solid substrate. iHP-treated DWV sources were ~105-fold less infectious when injected into naïve honey bee pupae compared to DWV receiving no iHP treatment, matching injected controls containing no DWV. iHP treatment also greatly reduced the incidence of overt DWV infections (i.e., pupae having >109 copies of DWV). The level of DWV inactivation achieved with iHP treatment was higher than other means of viral inactivation such as gamma irradiation, and iHP treatment is likely simpler and safer. Treatment of DWV contaminated hive substrates with iHP, even with honey bees present, may be an effective way to decrease the impacts of DWV infection on honey bees.

Adsorption mechanisms of inositol hexakisphosphate in the presence of phosphate at the amorphous aluminum oxyhydroxide-water interface

Myo-inositol hexakisphosphate (myo-IHP) is one of the most common soil organic phosphorus (P) species in soil. Its retention in soil is often competed by phosphate, making bioavailability of P species difficult. In this study, the adsorption mechanism of myo-IHP at the amorphous aluminum (oxyhydr)oxide (AAH)-water interface was investigated at pH 6.5 in the presence of phosphate using batch adsorption experiments and solution ³¹P NMR spectroscopy. The ratio of [myo-IHP]_i/[phosphate]_i (Ri) was kept 0.33-3 while ligand addition was varied. In the absence of phosphate, myo-IHP forms inner-sphere surface complexes in AAH via P1,3, P2, P4,6, and P5 functional group coordination. When two ligands were simultaneously added, fewer P functional groups of myo-IHP coordinated to AAH and the surface complexes were altered with the coordination of mainly P1,3 and P2 functional groups. When phosphate was pre-adsorbed, myo-IHP adsorption decreased by 8.0-44% compared to the respective simultaneous addition system. P2 or P5 functional group was predominantly coordinated to the AAH surfaces at Ri = 0.33. Myo-IHP pre-adsorption resulted in an increase in the final myo-IHP adsorption compared to that in the simultaneous addition system under the respective Ri values (0.33-3). In this system, P1,3, P2, P4,6, and P5 functional groups were coordinated to form inner-sphere surface complexes regardless of Ri. The study revealed that the functional group specific adsorption mechanism of myo-IHP at the AAH-water interface was affected by addition sequence and Ri of two ligands. The competitive adsorption between organic P and phosphate plays an important role in the fate of P in soils.

Solution 31P NMR Investigation of Inositol Hexakisphosphate Surface Complexes at the Amorphous Aluminum Oxyhydroxide-Water Interface

Phytate (myo-inositol hexakisphosphate, myo-IHP) is one of the most common organic phosphorus (P) species in soils and sediments which can be mineralized to increase the concentration of dissolved phosphate in pore water. Because of its six phosphate functional groups, functional group-specific adsorption mechanisms in reactive soil minerals become important in predicting solubility. In this study, solution ³¹P NMR was used to elucidate the functional group-specific adsorption mechanisms of myo-IHP at the amorphous Al hydroxide (AAH)-water interface at pH 6.5 in conjunction with batch adsorption experiments and Zetasizer measurements. The adsorption maximum of myo-IHP with AAH was ∼312.50 mmol kg^-1, and the charge reversal effects in IHP-reacted AAH particles suggested the presence of inner-sphere surface species. The upfield shifts of various phosphate groups in the NMR spectra further supported the formation of inner-sphere IHP complexes at the AAH-water interface. When the initial myo-IHP/AAH (mol kg^-1) was decreased from 2.5 to 1.25-1.67, P1,3 and P4,6 functional groups were coordinated in addition to P2; P5 became reactive with the ratio being decreased to <0.84, P5. This multifunctional group coordination increased aggregate size. The study showed that the availability of surface sites of adsorbents influenced the functional group-specific myo-IHP adsorption.

Hepatic Perfusion for Diffuse Metastatic Cancer to the Liver: Open and Percutaneous Techniques

The management of patients with diffuse liver metastases remains a significant clinical challenge. In many cancer patients, metastatic disease may be isolated to the liver or the liver may be the dominant site of progressive metastatic cancer. In this setting, progression of disease in the liver generally is the most significant cause of morbidity and mortality.

Prognostic values of baseline, interim and end-of therapy 18F-FDG PET/CT in patients with follicular lymphoma

Purpose

In the present study, we aimed to investigate the role of baseline, interim and end-of treatment positron emission tomography/computed tomography (PET/CT) in assessing the prognosis of follicular lymphoma (FL).

Methods

A total of 84 FL patients were retrospectively analyzed in this study. Baseline (n=59), interim (n=24, after 2–4 cycles) and end-of treatment (n=43) PET/CT images were re-evaluated, and baseline maximum standardized uptake value (SUV_max), total metabolic tumor volume (tMTV) and total lesion glycolysis (TLG) were recorded. Interim (I-PET) and end-of treatment (E-PET) PET/CT responses were interpreted by Deauville five-point scale (D-5PS) and International Harmonization Project criteria (IHP). Survival curves were calculated by Kaplan-Meier curves, and differences between groups were compared by log-rank test.

Results

The 2-year progression-free survival (PFS) of the high- and low-TLG groups was 57.14% and 95.56%, respectively (p=0.0001). The 2-year overall survival (OS) of the high- and low-TLG groups was 62.50% and 100%, respectively (p<0.0001). Multivariate analysis showed that TLG was an independent prognostic factor for PFS (p=0.001, HR=6.577, 95% CI=2.167–19.960) and OS (p=0.030, HR=19.291, 95% CI =2.689–137.947). Besides, Eastern Cooperative Oncology Group (ECOG) was the independent prognostic factor for OS (HR=8.924, 95% CI=1.273–62.559, p=0.028). Interim PET results based on D-5PS or IHP criteria were not significantly correlated with PFS (all p>0.05). However, E-PET results using D-5PS and IHP criteria were statistically significant (p=0.0001 and p=0.006). The D-5PS showed stronger prognostic value compared with IHP criteria. The optimal cutoff value of ΔSUV_max% was 66.95% according to I-PET and 68.97% according to E-PET. However, only the ΔSUV_max% from the baseline to the end-of therapy yielded statistically significant results in the prediction of PFS (p=0.0002).

Conclusion

Our findings indicated that the baseline TLG and E-PET results were significantly associated with prognosis in patients with FL.

Phosphorus K-edge XANES spectroscopy has probably often underestimated iron oxyhydroxide-bound P in soils

Phosphorus (P) K-edge X-ray absorption near-edge structure (XANES) spectra of orthophosphate (oPO₄) bound to soil Fe^III minerals (e.g. ferrihydrite, goethite) show a pre-edge signal at 2148-2152 eV. It is unknown whether organic P bound to Fe^III oxyhydroxides also show this feature. Otherwise, Fe-bound soil P may be underestimated by P K-edge XANES spectroscopy, because a large portion of Fe oxyhydroxide-bound P in soils is organic P. K-edge XANES spectra were obtained for different organic P compounds present in soils [inositol hexaphosphate (IHP), glucose-6-phosphate (G6P), adenosine triphosphate (ATP)] after sorption to ferrihydrite or goethite and compared with spectra of oPO₄ adsorbed to these minerals. P sorption to ferrihydrite increased in the sequence IHP ≪ G6P < oPO₄ < ATP. P sorption to goethite increased in the sequence G6P < oPO₄ ≪ ATP = IHP. Pre-edge signals in P K-edge XANES spectra of organic P adsorbed to Fe oxyhydroxides were markedly smaller compared with those of oPO₄ adsorbed to these minerals and absent for Fe^III oxyhydroxide-bound ATP as well as goethite-bound IHP. Linear combination fitting (LCF) performed on spectra of IHP, G6P or ATP adsorbed to ferrihydrite or goethite, using only spectra of Fe^III oxyhydroxide-bound oPO₄ as reference compounds for Fe-bound P, erroneously assigned >93% (ferrihydrite) or >41% (goethite) of Fe-bound P to non-Fe-bound P species. Inclusion of Fe^III oxyhydroxide-bound IHP as reference compounds markedly increased the recovery of oxyhydroxide-bound organic P. Thus, Fe-bound soil P has probably often been underestimated by LCF in soil XANES studies where IHP adsorbed to ferrihydrite and to goethite were not included as reference compounds.

FDG-PET/CT at the end of immuno-chemotherapy in follicular lymphoma: the prognostic role of the ratio between target lesion and liver SUVmax (rPET)

AIM

To retrospectively investigate the prognostic role of the ratio between target lesion and liver SUV_max (rPET) in patients with follicular lymphoma (FL) submitted to FDG-PET/CT at the end of immuno-chemotherapy (PI-PET), and to compare rPET with International Harmonization Project criteria (IHP), Deauville Score (5p-DS) and FL International Prognostic Index at diagnosis (FLIPI).

METHODS

Eighty-nine patients with FL undergoing PI-PET were evaluated. The receiver operating characteristic (ROC) approach was applied to identify the optimal cut-point of rPET with respect to 5-years progression free survival (PFS). The prognostic significance of rPET was compared with IHP, DS and FLIPI. Positive predictive value (PPV) and negative predictive value (NPV) were calculated using the presence of adverse events as gold standard.

RESULTS

The ROC analysis for rPET as predictor of progression showed an optimal rPET cut-point of 0.98. Patients with positive values of IHP, DS and rPET had a PFS of 50, 30 and 31%. PPV were of 56, 80 and 80%, NPV of 83, 86 and 88%, respectively. DS and rPET differed only in two patients. FLIPI was not predictive of progression and relapse.

CONCLUSIONS

rPET is a prognostic factor in patients with FL submitted to PI-PET. Although it has a similar prognostic power as DS, it can have methodological advantages over visual analysis. PI-PET with different evaluation systems has a stronger prognostic power than FLIPI at diagnosis, so it could be useful to identify patients with FL at risk for early relapse after immuno-chemotherapy.

IEP, IHP, and Section 504 Primer for New School Nurses

Three types of documents and their frequently used acronyms play a vital role in ensuring that students with disabilities have the planning, services, and accommodations necessary to facilitate attendance and success in the school setting. Federal and state laws, as well as state nurse practice acts, govern the process and eligibility of students for these services. School nurses play a vital role in these processes, and new school nurses benefit from a comparison of the terms along with a historical explanation of the acronyms.

How does hemoglobin generate such diverse functionality of physiological relevance?

The absolute values of the O2-affinities (P50, Klow, and Khigh) of hemoglobin (Hb) are regulated neither by changes in the static T-/R-quaternary and associated tertiary structures nor the ligation states. They are pre-determined and regulated by the extrinsic environmental factors such as pH, buffers, and heterotropic effectors. The effect and role of O2 on Hb are reversibly to drive the structural allosteric equilibrium between the T(deoxy)- and R(oxy)-Hb toward R(oxy)-Hb (the structural allostery). R(oxy)-Hb has a higher O2-affinity (Khigh) relative to that (Klow) of the T(deoxy)-Hb (Khigh>Klow) under any fixed environmental conditions. The apparent O2-affinity of Hb is high, as the globin matrix interferes with the dissociation process of O2, forcing the dissociated O2 geminately to re-bind to the heme Fe. This artificially increases [oxy-Hb] and concomitantly decreases [deoxy-Hb], leading to the apparent increases of the O2-affinity of Hb. The effector-linked high-frequency thermal fluctuations of the globin matrix act as a gating mechanism to modulate such physical, energetic, and kinetic barriers to enhance the dissociation process of O2, resulted in increases in [deoxy-Hb] and concomitant decrease in [oxy-Hb], leading to apparent reductions of the O2-affinity of Hb (the entropic allostery). The heme in Hb is simply a low-affinity O2-trap, the coordination structure of which is not altered by static T-/R-quaternary and associated tertiary structural changes of Hb. Thus, heterotrophic effectors are the signal molecule, which acts as a functional link between these two allosteries and generates the diverse functionality of Hb of physiological relevance. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.

Oxygen binding to partially nitrosylated hemoglobin

Reactions of nitric oxide (NO) with hemoglobin (Hb) are important elements in protection against nitrosative damage. NO in the vasculature is depleted by the oxidative reaction with oxy Hb or by binding to deoxy Hb to generate partially nitrosylated Hb (Hb-NO). Many aspects of the formation and persistence of Hb-NO are yet to be clarified. In this study, we used a combination of EPR and visible absorption spectroscopy to investigate the interactions of partially nitrosylated Hb with O2. Partially nitrosylated Hb samples had predominantly hexacoordinate NO-heme geometry and resisted oxidation when exposed to O2 in the absence of anionic allosteric effectors. Faster oxidation occurred in the presence of 2,3-diphosphoglycerate (DPG) or inositol hexaphosphate (IHP), where the NO-heme derivatives had higher levels of pentacoordinate heme geometry. The anion-dependence of the NO-heme geometry also affected O2 binding equilibria. O2-binding curves of partially nitrosylated Hb in the absence of anions were left-shifted at low saturations, indicating destabilization of the low O2 affinity T-state of the Hb by increasing percentages of NO-heme, much as occurs with increasing levels of CO-heme. Samples containing IHP showed small decreases in O2 affinity, indicating shifts toward the low-affinity T-state and formation of inert α-NO/β-met tetramers. Most remarkably, O2-equilibria in the presence of the physiological effector DPG were essentially unchanged by up to 30% NO-heme in the samples. As will be discussed, under physiological conditions the interactions of Hb with NO provide protection against nitrosative damage without impairing O2 transport by Hb's unoccupied heme sites. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.

Tertiary and quaternary effects in the allosteric regulation of animal hemoglobins

In the last decade, protein allostery has experienced a major resurgence, boosted by the extension of the concept to systems of increasing complexity and by its exploitation for the development of drugs. Expansion of the field into new directions has not diminished the key role of hemoglobin as a test molecule for theory and experimental validation of allosteric models. Indeed, the diffusion of hemoglobins in all kingdoms of life and the variety of functions and of quaternary assemblies based on a common tertiary fold indicate that this superfamily of proteins is ideally suited for investigating the physical and molecular basis of allostery and firmly maintains its role as a main player in the field. This review is an attempt to briefly recollect common and different strategies adopted by metazoan hemoglobins, from monomeric molecules to giant complexes, exploiting homotropic and heterotropic allostery to increase their functional dynamic range. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.