X-ray Ptychography Imaging of Human Chromosomes After Low-dose Irradiation.

Studies of the structural and functional role of chromosomes in cytogenetics have spanned more than 10 decades. In this work, we take advantage of the coherent X-rays available at the latest synchrotron sources to extract the individual masses of all 46 chromosomes of metaphase human B and T cells using hard X-ray ptychography. We have produced 'X-ray karyotypes' of both heavy metal-stained and unstained spreads to determine the gain or loss of genetic material upon low-level X-ray irradiation doses due to radiation damage. The experiments were performed at the I-13 beamline, Diamond Light Source, Didcot, UK, using the phase-sensitive X-ray ptychography method.

Quantitative phase measurements of human cell nuclei using X-ray ptychography.

The human cell nucleus serves as an important organelle holding the genetic blueprint for life. In this work, X-ray ptychography was applied to assess the masses of human cell nuclei using its unique phase shift information. Measurements were carried out at the I13-1 beamline at the Diamond Light Source that has extremely large transverse coherence properties. The ptychographic diffractive imaging approach allowed imaging of large structures that gave quantitative measurements of the phase shift in 2D projections. In this paper a modified ptychography algorithm that improves the quality of the reconstruction for weak scattering samples is presented. The application of this approach to calculate the mass of several human nuclei is also demonstrated.

Ultra-Structural Imaging Provides 3D Organization of 46 Chromosomes of a Human Lymphocyte Prophase Nucleus.

Three dimensional (3D) ultra-structural imaging is an important tool for unraveling the organizational structure of individual chromosomes at various stages of the cell cycle. Performing hitherto uninvestigated ultra-structural analysis of the human genome at prophase, we used serial block-face scanning electron microscopy (SBFSEM) to understand chromosomal architectural organization within 3D nuclear space. Acquired images allowed us to segment, reconstruct, and extract quantitative 3D structural information about the prophase nucleus and the preserved, intact individual chromosomes within it. Our data demonstrate that each chromosome can be identified with its homolog and classified into respective cytogenetic groups. Thereby, we present the first 3D karyotype built from the compact axial structure seen on the core of all prophase chromosomes. The chromosomes display parallel-aligned sister chromatids with familiar chromosome morphologies with no crossovers. Furthermore, the spatial positions of all 46 chromosomes revealed a pattern showing a gene density-based correlation and a neighborhood map of individual chromosomes based on their relative spatial positioning. A comprehensive picture of 3D chromosomal organization at the nanometer level in a single human lymphocyte cell is presented.

Use of 3D imaging for providing insights into high-order structure of mitotic chromosomes.

The high-order structure of metaphase chromosomes remains still under investigation, especially the 30-nm structure that is still controversial. Advanced 3D imaging has provided useful information for our understanding of this detailed structure. It is evident that new technologies together with improved sample preparations and image analyses should be adequately combined. This mini review highlights 3D imaging used for chromosome analysis so far with future imaging directions also highlighted.

Azithromycin susceptibility testing for Salmonella enterica isolates: discordances in results using MIC gradient strips.

BACKGROUND: Azithromycin resistance is emerging in typhoidal Salmonella. Confirmation of azithromycin MIC is the most frequent antibiotic susceptibility request made to the Gastrointestinal Bacteria Reference Unit (GBRU) laboratory in England by local diagnostic laboratories. OBJECTIVES: (i) Determine concordance between local diagnostic and reference laboratory estimations of azithromycin MIC by gradient strip in Salmonella enterica serovars Typhi and Paratyphi. (ii) Consider causes of variation. METHODS: Isolates from patients with enteric fever attending a central London hospital between May 2011 and April 2019 were tested for azithromycin susceptibility using gradient strips, according to EUCAST methodology. Matched local diagnostic and reference laboratory estimations of azithromycin and ciprofloxacin (as a comparator) MICs were included; concordance in estimations was examined. RESULTS: Local diagnostic laboratory readings overestimated azithromycin MIC values compared with the reference laboratory, resulting in poor concordance in susceptibility/resistance attribution (concordant susceptibility interpretation in 8/19, κ = 0). In contrast, ciprofloxacin MIC estimation demonstrated superior concordance (concordant susceptibility interpretation in 16/17, κ = 0.85). None of the isolates was resistant to azithromycin at the reference laboratory and no known genes associated with azithromycin resistance were detected in any isolate using WGS. CONCLUSIONS: Overestimation of azithromycin resistance is likely to be due to difficulty in interpreting the point of intersection of the 'trailing edge' with the gradient strip, used to determine MIC. We advise local diagnostic laboratories to review their experience and consider adopting a 'second reader' system to mitigate this.

Low awareness and use of post-exposure prophylaxis among adolescents and young adults in South Africa: implications for the prevention of new HIV infections.

The vulnerability of adolescents and young adults in South Africa to HIV and sexual violence is well documented. Post-exposure prophylaxis (PEP) is available for victims of sexual abuse in the country but awareness of this measure is required to maximise its HIV-prevention benefits. This study examined levels of PEP awareness and its correlates and the uptake of PEP among 772 students (16-24 years) in a South African university using stratified random sampling. Overall, we included more females (477) than males (295), reflecting the male-female ratio at the university. Adjusted and unadjusted logistic regression models were used to determine correlates of PEP awareness, which was low (24.1%), particularly among those who experienced sexual violence in the past year (19.8%) compared those who had not (24.8%). Only 2.6% of participants had used PEP, while 7.5% had seen it, and 14.6% knew where to get it. In the adjusted model, adequate family support (AOR: 2.22; CI: 1.54-3.20) and prior HIV testing (AOR: 2.65; CI: 1.59-4.42) were associated with a higher likelihood of PEP awareness. The study concluded that awareness of PEP was low in the study setting and especially among those who need it. Social marketing of PEP is needed in the study settings to realise the maximum benefits of PEP in preventing new HIV infections.

Comparative slaughter performance and carcass quality of three Ethiopian fat-tailed hair sheep breeds supplemented with two levels of concentrate.

A study was conducted to compare carcass and noncarcass yield, carcass composition, conformation, and fat depot partitioning of three Ethiopian fat-tailed hair sheep breeds (Blackhead Ogaden (BHO), Horro, and Washera) under two concentrate supplement levels (CSL). Sixteen sheep from each genotype (8 sheep per concentrate level), a total of 48, were used in a 3 × 2 factorial arrangement (3 breeds and 2 CSL). The two CSL were 1% (L1) and 1.75% (L2) body weight. Animals were about a year of age at the start of the experiment and all were slaughtered after 90 days of fattening. Dressing percentage per SBW was in the orders of Horro > BHO = Washera (P < 0.001). Total edible noncarcass component yield per EBW (TENCCY/EBW) of Horro breed (21%) was heavier (P < 0.0001) by about 2.8% than that from BHO and Washera sheep. Blackhead Ogaden sheep had significantly (P < 0.05) higher fat percentage and fat to bone ratio, while lower lean to fat ratio than Horro and Washera sheep. The fat partitioning results showed that carcass depot is the major fat depot in BHO and Horro sheep, whereas carcass fat and tail fat in Washera sheep had comparable value. The highest (P < 0.0001) carcass compactness index (CCI) value was obtained in Horro sheep, while the value for Washera was the lowest coupled with leg compactness index; as a result, Washera sheep had poor carcass conformation. Sheep supplemented with L2 had heavier HCW and CCW (P < 0.0001), wider RMA, and dressed better (P < 0.001) than L1-fed sheep. Carcass fat per CCW, carcass fat per total body fat (TBF), TYEP per SBW, and CCI values of the L2 diet-fed group were 2.7, 1.8, 1.2%, and 13.2 g/cm, respectively, higher (P < 0.05) than L1-supplemented sheep. The result highlights that Horro and Washera have closely comparable carcass composition, indicating the two breeds were at a similar stage of physiological maturity, while BHO appeared to be an early maturing sheep, suggesting a need for different feeding management for BHO to harvest lean meat. In conclusion, there existed a significant breed variation in most parameters considered in this study, which can be an opportunity to select breeds for various use and production objectives.

Photoinduced Domain Pattern Transformation in Ferroelectric-Dielectric Superlattices.

The nanodomain pattern in ferroelectric-dielectric superlattices transforms to a uniform polarization state under above-band-gap optical excitation. X-ray scattering reveals a disappearance of domain diffuse scattering and an expansion of the lattice. The reappearance of the domain pattern occurs over a period of seconds at room temperature, suggesting a transformation mechanism in which charge carriers in long-lived trap states screen the depolarization field. A Landau-Ginzburg-Devonshire model predicts changes in lattice parameter and a critical carrier concentration for the transformation.

Thermal Fluctuations of Ferroelectric Nanodomains in a Ferroelectric-Dielectric PbTiO_{3}/SrTiO_{3} Superlattice.

Ferroelectric-dielectric superlattices consisting of alternating layers of ferroelectric PbTiO_{3} and dielectric SrTiO_{3} exhibit a disordered striped nanodomain pattern, with characteristic length scales of 6 nm for the domain periodicity and 30 nm for the in-plane coherence of the domain pattern. Spatial disorder in the domain pattern gives rise to coherent hard x-ray scattering patterns exhibiting intensity speckles. We show here using variable-temperature Bragg-geometry x-ray photon correlation spectroscopy that x-ray scattering patterns from the disordered domains exhibit a continuous temporal decorrelation due to spontaneous domain fluctuations. The temporal decorrelation can be described using a compressed exponential function, consistent with what has been observed in other systems with arrested dynamics. The fluctuation speeds up at higher temperatures and the thermal activation energy estimated from the Arrhenius model is 0.35±0.21 eV. The magnitude of the energy barrier implies that the complicated energy landscape of the domain structures is induced by pinning mechanisms and domain patterns fluctuate via the generation and annihilation of topological defects similar to soft materials such as block copolymers.

Nuclear incorporation of iron during the eukaryotic cell cycle.

Scanning X-ray fluorescence microscopy has been used to probe the distribution of S, P and Fe within cell nuclei. Nuclei, which may have originated at different phases of the cell cycle, are found to show very different levels of Fe present with a strongly inhomogeneous distribution. P and S signals, presumably from DNA and associated nucleosomes, are high and relatively uniform across all the nuclei; these agree with X-ray phase contrast projection microscopy images of the same samples. Possible reasons for the Fe incorporation are discussed.

Integrated view of genome structure and sequence of a single DNA molecule in a nanofluidic device.

We show how a bird's-eye view of genomic structure can be obtained at ∼1-kb resolution from long (∼2 Mb) DNA molecules extracted from whole chromosomes in a nanofluidic laboratory-on-a-chip. We use an improved single-molecule denaturation mapping approach to detect repetitive elements and known as well as unique structural variation. Following its mapping, a molecule of interest was rescued from the chip; amplified and localized to a chromosome by FISH; and interrogated down to 1-bp resolution with a commercial sequencer, thereby reconciling haplotype-phased chromosome substructure with sequence.

Choice of antihypertensive medications among physicians and its impact on blood pressure control among Nigerians living with hypertension.

Background: Hypertension, if untreated or uncontrolled, leads to damage of vital organs such as the brain, heart and the kidneys among others. These complications have been shown to be severer in black Africans. Benefit of treatment has been repeatedly demonstrated by many studies. Therefore, many guidelines have been produced by relevant bodies in different countries in order to assist physicians in making the right choices for blood pressure (BP) control. Most of these bodies produce the guidelines based on the peculiarities of hypertension in their respective population. Several reports have shown how different hypertension is, in black Africans, still there is no published unified guideline for its treatment in this population. Methods: This was a survey of known hypertensives who were on follow up visit. Their prescriptions were assessed for drug name, class and number. Their blood pressures at that visit were also recorded. Prevalence of single therapy and combination therapy were determined. Compliance with the AHA recommended 2 ­ drug combination was determined. The percentage of BP control as well as the prescribed drugs in each group were also obtained. Results: Those on single agents were 13% out of which 52% were controlled. 87% were on various combination of 2 or more drugs of whom 41.9% of those on 2 drugs and 21.1% of those on more than 2 drugs had controlled BP. BP control in those on 2 drugs was better than in those with > 2 drugs, (p=0.0027). ACEI were the commonest used drug either as single agent (55.9%) or as 2 ­ drug combination as seen in 54.8% of the subjects on 2 ­ drug combination. 13 different 2 ­ drug combinations were identified with the best control in ARB + Diuretic, ACEI + Diuretic and CCB + Diuretic. The least control was observed in the ACEI + CCB group. Compliance with AHA recommendation was good but still 7.7% were under unacceptable group while another 7.7% were unclassified. Conclusion: ACE-Is are becoming the drugs of choice both as monotherapy and as combination therapy. Despite good compliance to AHA recommendation on drug combination, overall control is still a problem which calls for a revisit of these recommendations in Africans.

Karyotyping human chromosomes by optical and X-ray ptychography methods.

Sorting and identifying chromosomes, a process known as karyotyping, is widely used to detect changes in chromosome shapes and gene positions. In a karyotype the chromosomes are identified by their size and therefore this process can be performed by measuring macroscopic structural variables. Chromosomes contain a specific number of basepairs that linearly correlate with their size; therefore, it is possible to perform a karyotype on chromosomes using their mass as an identifying factor. Here, we obtain the first images, to our knowledge, of chromosomes using the novel imaging method of ptychography. We can use the images to measure the mass of chromosomes and perform a partial karyotype from the results. We also obtain high spatial resolution using this technique with synchrotron source x-rays.

Determinants and Magnitude of Neonatal Sepsis at Hiwot Fana Comprehensive Specialized University Hospital, in Eastern Ethiopia: A Cross-Sectional Study.

Background: Neonatal sepsis is a serious blood bacterial infection in neonates at the age of equal to or less than 28 days of life, and it's still the major significant cause of death and long-term morbidity in developing countries. Objective: This study aimed to assess the prevalence and related factors with neonatal sepsis among newborns admitted to the neonatal intensive care unit at Hiwot Fana Comprehensive Specialized University Hospital, Harar, Ethiopia. Methods: An institutional-based retrospective cross-sectional study design was conducted among 386 neonates admitted to Neonatal Intensive Care Unit from September 2017 to August 2019. A systematic random sampling method was used. Data were analyzed using SPSS V.26. Descriptive summary statistics were done. Bivariate regression and multivariate analysis were computed. Variables with P-value <.05 were declared as having a statistically significant association. Result: The prevalence of neonatal sepsis was 53.1%. Among the total neonates who had sepsis, 67.8% had early neonatal sepsis. Among neonatal factors, preterm neonates (AOR: 8.1, 95%CI: 2.1, 31.2), birth asphyxia (AOR: 4.7, 95%CI: 1.6, 13.6); and among maternal factors, urban residence (AOR: 0.26, 95%CI: 0.1, 0.5), antenatal care attendance (AOR: 0.32, 95%CI: 0.2, 0.6), spontaneous vaginal delivery (AOR: 0.047, 95%CI: 0.01, 0.2), and maternal antibiotic use (AOR: 0.39; 95%CI: 0.2, 0.8) were found to have significant association with neonatal sepsis. Conclusion: Overall, the magnitude of neonatal sepsis was high. Provision of neonatal and obstetrics care as per standard during prenatal, intranatal, and postnatal periods is needed. Training of health professionals on infection prevention and safe delivery practice should be provided.

A Path of Novelty from Nanoparticles to Nanobots: Theragnostic Approach for Targeting Cancer Therapy.

Pharmaceutical development of cancer therapeutics is a dynamic area of research. Even after decades of intensive work, cancer continues to be a dreadful disease with an ever-increasing global incidence. The progress of nanotechnology in cancer research has overcome inherent limitations in conventional cancer chemotherapy and fulfilled the need for target-specific drug carriers. Nanotechnology uses the altered patho-physiological microenvironment of malignant cells and offers various advantages like improved solubility, reduced toxicity, prolonged drug circulation with controlled release, circumventing multidrug resistance, and enhanced biodistribution. Early cancer detection has a crucial role in selecting the best drug regime, thus, diagnosis and therapeutics go hand in hand. Furthermore, nanobots are an amazing possibility and promising innovation with numerous significant applications, particularly in fighting cancer and cleaning out blood vessels. Nanobots are tiny robots, ranging in size from 1 to 100 nm. Moreover, the nanobots would work similarly to white blood cells, watching the bloodstream and searching for indications of distress. This review articulates the evolution of various organic and inorganic nanoparticles and nanobots used as therapeutics, along with their pros and cons. It also highlights the shift in diagnostics from conventional methods to more advanced techniques. This rapidly growing domain is providing more space for engineering desired nanoparticles that can show miraculous results in therapeutic and diagnostic trials.

Surface Modification Strategies for Chrysin-Loaded Iron Oxide Nanoparticles to Boost Their Anti-Tumor Efficacy in Human Colon Carcinoma Cells.

Enhancing nanoparticles' anti-cancer capabilities as drug carriers requires the careful adjustment of formulation parameters, including loading efficiency, drug/carrier ratio, and synthesis method. Small adjustments to these parameters can significantly influence the drug-loading efficiency of nanoparticles. Our study explored how chitosan and polyethylene glycol (PEG) coatings affect the structural properties, drug-loading efficiency, and anti-cancer efficacy of Fe3O4 nanoparticles (NPs). The loading efficiency of the NPs was determined using FTIR spectrometry and XRD. The quantity of chrysin incorporated into the coated NPs was examined using UV-Vis spectrometry. The effect of the NPs on cell viability and apoptosis was determined by employing the HCT 116 human colon carcinoma cell line. We showed that a two-fold increase in drug concentration did not impact the loading efficiency of Fe3O4 NPs coated with PEG. However, there was a 33 Å difference in the crystallite sizes obtained from chitosan-coated Fe3O4 NPs and drug concentrations of 1:0.5 and 1:2, resulting in decreased system stability. In conclusion, PEG coating exhibited a higher loading efficiency of Fe3O4 NPs compared to chitosan, resulting in enhanced anti-tumor effects. Furthermore, variations in the loaded amount of chrysin did not impact the crystallinity of PEG-coated NPs, emphasizing the stability and regularity of the system.