SIRT7: an influence factor in healthy aging and the development of age-dependent myeloid stem-cell disorders

Molecular alterations within the hematopoietic system influence cellular longevity and development of age-related myeloid stem-cell disorders like acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). A reduced SIRT7-expression in aged murine hematopoietic stem cells (HSC) resulted in reduced longevity and increased proliferation. In this study we investigated age-related changes of SIRT7-expression in healthy humans and relevant pathomechanisms in AML and CML. SIRT7-expression in leukocytes of healthy people decreased in an age-dependent manner. Low SIRT7 mRNA levels were also detected in AML and CML patients. With positive treatment response, SIRT7-expression increased, but showed reduction when patients progressed or relapsed. Pharmacologic inhibition of driver mutations in AML (FLT3-ITD) or CML (BCR-ABL) also restored SIRT7 levels in cell lines and patient samples. Furthermore, SIRT7-expression increased with time during PMA-mediated monocyte differentiation of THP-1 cells. SIRT7-overexpression in THP-1 cells resulted in increased expression of differentiation markers. BCR-ABL, FLT3-ITD, and differentiation-associated SIRT7-expression in general were positively regulated by C/EBPα, -β, and -ε binding to two different C/EBP-binding sites within the SIRT7 promoter. SIRT7 is important in human hematopoietic cell aging and longevity. It might act as tumor suppressor and could potentially serve as general biomarker for monitoring treatment response in myeloid stem-cell disorders.

Time-Dependent Perspective for the Intramolecular Couplings of the N–H Stretches of Protonated Tryptophan

Quasi-classical direct dynamics simulations, performed with the B3LYP-D3/cc-pVDZ electronic structure theory, are reported for vibrational relaxation of the three NH stretches of the −NH₃⁺ group of protonated tryptophan (TrpH⁺), excited to the n = 1 local mode states. The intramolecular vibrational energy relaxation (IVR) rates determined for these states, from the simulations, are in good agreement with the experiment. In accordance with the experiment, IVR for the free NH stretch is slowest, with faster IVR for the remaining two NH stretches which have intermolecular couplings with an O atom and a benzenoid ring. For the free NH and the NH coupled to the benzenoid ring, there are beats (i.e., recurrences) in their relaxations versus time. For the free NH stretch, 50% of the population remained in n = 1 when the trajectories were terminated at 0.4 ps. IVR for the free NH stretch is substantially slower than for the CH stretch in benzene. The agreement found in this study between quasi-classical direct dynamics simulations and experiments indicates the possible applicability of this simulation method to larger biological molecules. Because IVR can drive or inhibit reactions, calculations of IVR time scales are of interest, for example, in unimolecular reactions, mode-specific chemistry, and many photochemical processes.

Crane Principle in Plastic Surgery- Experience in Mymensingh Medical College Hospital

The crane principle is a Plastic surgical technique whereby, a pedicled flap can be used as an engineering crane to lift and transport subcutaneous tissue from one area and deposit it in another. The flap can be returned later to its original bed. It takes only one week for the conveyance. Here we present a case of 25 year old female patient with degloving injury of scalp with exposed skull bone was initially managed with transposition flap for coverage of the scalp defect in Mymensingh Medical College Hospital (MMCH), Mymensingh, Bangladesh on 07 December 2017. After 8 months the scalp flap was returned to its original site following the crane principle and the new wound was covered by split-thickness skin graft. The flap survived completely and patient was satisfied.

Genetic diversity and population structure of Culex modestus across Europe: does recent appearance in the United Kingdom reveal a tendency for geographical spread?

In mainland Europe, the mosquito species Culex modestus Ficalbi (1890) is a bridge vector for West Nile virus (WNV) from its natural bird-mosquito cycle to mammals. The present study assessed the genetic diversity of Cx. modestus, as well as related Culex species, using the mitochondrial COI DNA barcoding region and compared this with the population structure across Europe. A haplotype network was mapped to determine genealogical relationships among specimens. The intraspecific genetic diversity within individual Culex species was below 2%, whereas the interspecific genetic divergence varied from 2.99% to 13.74%. In total, 76 haplotypes were identified among 198 sequences. A median-joining network determined from 198 COI sequences identified two major lineages that were separated by at least four mutation steps. A high level of intraspecific genetic diversity was not detected in Cx. modestus in samples submitted from different European populations, which indicates that morphologically identified specimens represent a single species and not a species complex. Therefore, it is deduced that different populations of Cx. modestus will show a similar potential to transmit WNV, lending support to concerns that the population present in southeast England represents a risk of transmission to humans.

Iterative training set refinement enables reactive molecular dynamics via machine learned forces

Machine learning approaches have been successfully employed in many fields of computational chemistry and physics. However, atomistic simulations driven by machine-learned forces are still very challenging. Here we show that reactive self-sputtering from a beryllium surface can be simulated using neural network trained forces with an accuracy that rivals or exceeds other approaches. The key in machine learning from density functional theory calculations is a well-balanced and complete training set of energies and forces. We have implemented a refinement protocol that corrects the low extrapolation capabilities of neural networks by iteratively checking and improving the molecular dynamic simulations. The sputtering yield obtained for incident energies below 100 eV agrees perfectly with results from ab initio molecular dynamics simulations and compares well with earlier calculations based on pair potentials and bond-order potentials. This approach enables simulation times, sizes and statistics similar to what is accessible by conventional force fields and reaching beyond what is possible with direct ab initio molecular dynamics. We observed that a potential fitted to one surface, Be(0001), has to be augmented with training data for another surface, Be(011̄0), in order to be used for both.

Reactive self-sputtering from a Be surface is simulated using neural network trained forces with high accuracy. The key in machine learning from DFT calculations is a well-balanced and complete training set of energies and forces obtained by iterative refinement.

Clusters of betaine with positive and negative ions: Evidence for the betaine tetramer being magic

Betaine (Bet) is a pure zwitterion with an extraordinarily large dipole moment, which allows it to form stable clusters in the gas phase of the form X^±Bet_N, where X^± is a positive or negative ion. We show here that such clusters have a prominent magic number at N = 4 for all X^± ions used in this work. Nevertheless, we observe a marked difference in the fragmentation pattern of anionic and cationic clusters: while cationic clusters fragment by evaporating one betaine monomer at a time, fragmentation of anionic clusters is through fission resulting in the emission of one or several betaine molecules. Theoretical calculations show that charged betaine tetramers have a square like structure with the central ion lying above the cluster plane and explain the difference in fragmentation patterns as a result of the charge distribution within the betaine molecule.

Establishment of a clinically relevant large animal model to assess the healing of metaphyseal bone

Despite the high incidence of metaphyseal bone fractures in patients, the mechanisms underlying the healing processes are poorly understood due to the lack of suitable experimental animal models. Hence, the present study was conducted to establish and characterise a clinically relevant large-animal model for metaphyseal bone healing. Six female adult Merino sheep underwent full wedge-shaped osteotomy at the distal left femur metaphysis. The osteotomy was stabilised internally with a customised anatomical locking titanium plate that allowed immediate post-operative full-weight bearing. Bone healing was evaluated at 12 weeks post-fracture relative to the untouched right femur. Histological and quantitative micro-computed tomography results revealed an increased mineralised bone mass with a rich bone microarchitecture. New trabeculae healed by direct intramembranous ossification, without callus and cartilaginous tissue formation. Stiffness at the cortical and trabecular regions was comparable in both groups. Functional morphological analysis of the osteocyte lacunae revealed regularly arranged spherically shaped lacunae along with the canalicular network. Bone surface biochemical analysis using time-of-flight secondary-ion mass spectrometry showed high and homogeneously distributed levels of calcium and collagenous components. Ultrastructure imaging of the new trabeculae revealed a characteristic parallel arrangement of the collagen fibrils, evenly mineralised by the dense mineral substance. The specialised bone cells were also characterised by their unique structural features. Bone remodelling in the fractured femur was evident in the higher expression levels of prominent bone formation and resorption genes. In conclusion, the novel metaphyseal fracture model is beneficial for studying healing and treatment options for the enhancement of metaphyseal bone defects.

Posterior Tibial Artery Perforator Based Propeller Flap for Lower Leg and Ankle Defect Coverage: A Prospective Observational Study

Reconstruction of lower leg and ankle defect with exposed bone or tendon is a challenging task for a Plastic Surgeon. There are various options, among them perforator based propeller flap is a very good option though this is a microsurgical procedure but no need of microvascular anastomosis. This study was designed to see the clinical results of Posterior tibial artery perforator based propeller flap for lower leg and ankle defect coverage. The study was a prospective observational study. It was conducted in the Department of Burn and Plastic Surgery, Mymensingh Medical College Hospital, Mymensingh, Bangladesh from July 2017 to June 2018. Sample size was 9. Sampling was carried out purposively. Postoperative follow up period was up to 6 weeks. Among the 9 cases, 8 flaps completely survived, 1 case developed marginal necrosis which was secondarily healed. There were total 2 complications among 9 cases i.e. transient venous congestion and superficial epidermonecrolysis which were resolved spontaneously. Regarding the cause of the defect, maximum cases were post traumatic wound (66.7%), others were post infective, post malignancy excision and post electric burn wound. Defect size was 2cm×2cm to 7cm×5cm. Maximum dimension of the flap was 19cm×6cm and minimum size was 7cm×3cm. Posterior tibial artery perforator location was 4cm to 9cm from lowest level of medial malleolous (mean 6.2±1.6cm). Rotation of the flap was 145°-180° (mean 163°±1.39°). In all cases donor site was covered with split thickness skin graft. Operation time was 120 minutes to 180 minutes; mean operative time was 143.3±2.38 minutes. After operation hospital stay was 10 days to 21 days, mean 11.44±3.64 days. So, posterior tibial artery perforator based propeller flap for lower leg and ankle defect coverage is a very good option.

Variability in space and time: contrasting fruit distribution patterns in the deceptive orchid Orchis militaris

In angiosperms, a decrease in fruit production towards the apex of individual inflorescences is usually observed. Orchids are thought to be primarily pollination-limited species, and non-uniform pollination could cause this decrease pattern in several species. Fruit production was investigated in relation to flower position and floral display size in Orchis militaris (Orchidaceae), a deceptive species. Over 2 years, eight populations of O. militaris were studied and fruit position along the inflorescence was recorded. Generalised linear models were performed to examine the effect of population, year, flower position and floral display size on fruit production. The dominant pattern was characterised by a higher fruit set in the middle part of the inflorescence (parabolic pattern). A non-directional pattern of fruit production was also detected in some populations. Within a given population, patterns were generally consistent among years. In one of the two study years and in one of the eight populations specifically, the proximal-to-distal decrease in fruit production was dramatic in plants with a large floral display but weak or absent in small displays. Our study demonstrates the intraspecific diversity of fruit distribution patterns in O. militaris. Non-uniform pollination along the inflorescence is likely to be responsible for the parabolic pattern, while irregular visitation could explain the non-directional pattern of fruit production. Pattern variation among years and between populations could arise from spatiotemporal variation in pollinator assemblages. Resource competition effects could explain the interaction effect between display size and flower position.

Fetomaternal Outcome in Eclampsia in Relationship with Gravidity

Eclampsia is a well-recognized major cause of maternal and perinatal morbidity and mortality. Patient's age, occupational status, socioeconomic status, educational status, regular ANC (antenatal care) and gravidity may affect the outcome of mother and foetus. The purpose of this study is to see the fetomaternal outcome in eclampsia in relationship with gravidity. This prospective observational cross-sectional study carried out among the alternate cases of primigravid and multigravid eclamptic patients. Total number of patients was 100 eclamptic patients among them, 50 patients were primigravida and 50 patients were multigravida. The study was conducted in Eclampsia unit of Department of Gynaecology and Obstetrics, Dhaka Medical College Hospital, Dhaka, Bangladesh from 21 November 2011 to 20 May 2012. In this study, it was observed that ARF (acute renal failure) occurred in 6%, of these 4 cases of multigravida and 2 cases of primigravida. Cerebro vascular accident (CVA) was reported in 16 patients and 26% in multigravida and 6% in primigravid patients. HELLP (Haemolysis, Elevated liver enzymes and low platelets) syndrome developed in 25 cases of multigravida and 6 cases of primigravida. Heart failure occurred in 7% cases, out of these 6 cases were multigravida and 1 case was primigravida. Pulmonary edema was observed in 41%, among were 21 cases of multigravida and 20 cases of primigravida. Incidence of DIC (disseminated intravascular coagulation) was noted in 2 cases of multigravida and 1 case of primigravida. PPH (postpartum haemorrhage) occurred in 10 cases of multigravida and 3 cases of primigravid patients. Puerperal psychosis was reported in 8% of multigravida and 4% of primigravida. Total 4% of patients expired, among them 3 cases were multigravida and 1 case was primigravida. Perinatal mortality was 21 cases in multigravida and 8 cases in primigravida. The incidence of live birth, in case of multigravida was 39 cases and primigravida 45 cases. Data were analyzed by paired student's 't' test. There was no statistically significant difference between primi and multigravida in feto-maternal outcome. This study reveals that gravidity does not alter the feto-maternal outcome in eclampsia.

Vibrational Predissociation Spectroscopy of Cold Protonated Tryptophan with Different Messenger Tags

Vibrational spectra of protonated tryptophan were recorded by predissociation of H₂ messenger tags using cryogenic ion traps. We explore the issue of messenger induced spectral changes by solvating TrpH⁺(H₂) _n with n = 1-5 to obtain single photon vibrational spectra of TrpH⁺ and of its partly deuterated isotopomer in the spectral region of 800-4400 cm^-1. Depending on the number of messenger molecules, the spectra of several conformational isomers associated with multiple H₂ binding locations along with two natural conformations of TrpH⁺ were found using the two photon MS³IR² conformational hole burning method. Most probable messenger positions were established by comparison with predictions from DFT calculations on various candidate structures. Mechanical anharmonicity effects associated with the charged amino group were modeled by Born-Oppenheimer ab initio molecular dynamics. The spectra of TrpH⁺(H₂O) _m=1,2, recorded by infrared multiphoton dissociation (IRMPD), reveal broad features in the NH stretching region of the NH₃⁺ group, indicating strong hydrogen bonding in acceptor-donor configuration with the benzene ring for the first water molecule, while the second water appears to attach to a less strongly perturbing site, yielding unique transitions associated with the free OH stretching fundamentals. We discuss the structural deformations induced by the water molecules and compare our results to recent experiments on similar hydrated cationic systems.

Uptake and accommodation of water clusters by adamantane clusters in helium droplets: interplay between magic number clusters

We report an experimental study of water clusters as guests in interactions with clusters of adamantane (Ad) as hosts that occur in doped helium droplets at extremely low temperatures. Separate experiments with pure water as dopant showed ready formation of a distribution of water clusters (H2O)mH+ that peaks at m = 11 and extends beyond m = 100 with local maxima at m = 4, 11, 21, 28 and 30 with (H2O)21H+ being the most anomalous and showing the greatest stability with respect to clusters immediately adjacent in water content. When adamantane is also added as a dopant, extensive hydration is seen in the formation of water/adamantane clusters, (H2O)mAdn+; magic number clusters (H2O)21Adn+ are seen for all the adamantane clusters. Other magic numbers for water clusters attached to adamantane, (H2O)mAdn+, are as for pristine protonated water, with m = 28 and m = 30. The icosahedral shell closure of pure adamantane at n = 13 and 19 appears to be preserved with (H2O)21 replacing one adamantane. (H2O)21Ad12+ and (H2O)21Ad18+ stand out in intensity and demonstrate the interplay of magic number water clusters with magic number adamantane clusters, observed perhaps for the first time in gas-phase cluster chemistry. There was no clear evidence for the formation of clathrate hydrates in which adamantane is trapped within structured water.

Highly Stable [C60AuC60]+/- Dumbbells

Ionic complexes between gold and C₆₀ have been observed for the first time. Cations and anions of the type [Au(C₆₀)₂]^+/- are shown to have particular stability. Calculations suggest that these ions adopt a C₆₀-Au-C₆₀ sandwich-like (dumbbell) structure, which is reminiscent of [XAuX]^+/- ions previously observed for much smaller ligands. The [Au(C₆₀)₂]^+/- ions can be regarded as Au(I) complexes, regardless of whether the net charge is positive or negative, but in both cases, the charge transfer between the Au and C₆₀ is incomplete, most likely because of a covalent contribution to the Au-C₆₀ binding. The C₆₀-Au-C₆₀ dumbbell structure represents a new architecture in fullerene chemistry that might be replicable in synthetic nanostructures.