Antimicrobial and cytotoxic naphthoquinones from microbial origin: An updated review

Naphthoquinones (NQs) are small molecules bearing two carbonyl groups. They have been the subject of much research due to their significant biological activities such as antiproliferative, antimicrobial, anti-inflammatory, antioxidant, and antimalarial effects. NQs are produced mainly by bacteria, fungi and higher plants. Among them, microorganisms are a treasure of NQs with diverse skeletons and pharmacological properties. The purpose of the present study is to provide a comprehensive update on the structural diversity and biological activities of 91 microbial naphthoquinones isolated from 2015 to 2022, with a special focus on antimicrobial and cytotoxic activities. During this period, potent cytotoxic NQs such as naphthablin B (46) and hygrocin C (30) against HeLa (IC50=0.23 µg/ml) and MDA-MB-431 (IC50=0.5 µg/ml) cell lines was reported, respectively. In addition, rubromycin CA1 (39), exhibited strong antibacterial activity against Staphylococcus aureus (MIC of 0.2 µg/ml). As importance bioactive compounds, NQs may open new horizon for treatment of cancer and drug resistant bacteria. As such, it is hoped that this review article may stimulates further research into the isolation of further NQs from microbial, and other sources as well as the screening of such compounds for biological activity and beneficial uses.

Circulating levels of metabolic biomarkers of site-specific and sex-specific arterial calcification in the multi-cohort BBMRI setting

Background/Introduction

Increasing evidence shows that greater arterial calcification leads to an elevated risk of atherosclerotic cardiovascular disease. Risk factors and prognosis of arterial calcification seems to vary per site and between women and men. However, the underlying biological mechanisms of site-specific calcification and the associated sex differences are largely unknown. Within the BBMRI framework, we performed a multi-cohort study on the associations of the circulating levels of metabolic biomarkers with arterial calcification at various sites among women and men.

Purpose

To examine the associations of the circulating levels of metabolic biomarkers with coronary artery (CAC), aortic arch (AAC) and the aortic valve (AVC) calcifications among women and men.

Methods

We included a total of 1,114 participants from the population-based Rotterdam Study and 390 from the Leiden Longevity Study. Study populations were comparable concerning study characteristics. Blood samples were used to determine a wide range of plasma metabolic biomarkers by proton nuclear magnetic resonance (NMR). Participants underwent non-contrast computed tomography to quantify the volume of CAC, AAC, and AVC. Linear regression modelling adjusted for relevant covariates was used to assess the associations of 166 metabolic biomarkers with CAC, AAC, and AVC. Correction for multiple testing was based on 33 independent metabolic biomarkers (p-value 0.05/33 = 1.5 x 10–3).

Results

Mean (standard deviation - SD) age was 69.5 (6.8) and 780 (52.0%) of the study population were women. One SD increase in concentration of a1-acid glycoprotein, was associated with a 0.10 SD (standard error (SE) = 0.03) increase in AAC (p-value = 9.5x10–4) in the overall population (Figure 1). When we stratified our analyses based on sex, this association was mainly driven by men [beta (SE) per SD: 0.12 (0.05), p-value = 0.007]. Moreover, an SD increase in acetate was associated with a 0.14 SD (SE = 0.04) decrease in CAC (p-value 1.7x10–4) in women but not in men [beta (SE) per SD: −0.04 (0.03), p-value = 0.22] (Figure 1).

Conclusion(s)

Higher levels of circulating glycoproteins were associated with increased AAC in men. Moreover, lower levels of circulating acetate were associated with increased CAC in women. These results provide evidence for location-specific differences and sex-specific effects in the underlying biological mechanisms of atherosclerosis. Our findings carry the potential to contribute to the early detection of individuals at increased risk for developing atherosclerotic cardiovascular disease and to a better understanding of disease etiology.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was performed within the framework of the BBMRI Metabolomics Consortium funded by BBMRI-NL, a research infrastructure financed by the Dutch government through Netherlands Organisation for Scientific Research (NWO) (Grant Nos. 184.021.007 and 184033111). MK was supported by VENI grant (91616079) from The Netherlands Organization for Health Research and Development (ZonMw).

Association of SRD5A2 gene mutations with risk of hypospadias in the Iranian population

BACKGROUND

Hypospadias is one of the most common forms of congenital malformation of the male external genitalia worldwide. The ratio in the Iranian population is one in 250 live male births. The conversion of testosterone to dihydrotestosterone (DHT) in the presence of steroid 5α-reductase 2, which is encoded by SRD5A2 gene, plays an important role in the normal development of the male reproductive system.

METHODS

We examined whether SRD5A2 gene mutations (V89L and A49T polymorphisms) are associated with the risk of hypospadias in the Iranian population. We performed exons sequencing for SRD5A2 gene in 109 hypospadias patients.

RESULTS

We identified two new mutations in the subgroups of affected cases: including a substitution of the nucleotide T > A in the codon 73 [c.219T > A (p.Leu73_Ser74insHisPro)] and an insertion of an extra A nucleotide in the codon 77 [c.229insA* (p.Gly77*)]. Additionally, we performed PCR-RFLP for the two identified polymorphisms and revealed that V89L [OR = 5.8, 95% CI (3.8-8.8), p value < 0.001] and A49T [OR = 10.16, 95% CI (3.94-26.25), p value < 0.001] are significantly associated with hypospadias occurrence in patients. Our haplotype analysis further indicated that the Leu-Ala haplotype increases risk of hypospadias; conversely, the Val-Ala haplotype decreases the risk of hypospadias in the studied patients.

CONCLUSIONS

This study demonstrates that polymorphisms in the SRD5A2 gene could be considered as a risk factor for hypospadias disease emergence.

Preparation and characterization of a novel highly hydrophilic and antifouling polysulfone/nanoporous TiO2 nanocomposite membrane

In this research, novel ultrafiltration nanocomposite membranes were prepared by incorporating self-synthesized nanoporous titanium dioxide (NTiO2) nanoparticles into polysulfone. The surface of the nanoparticle was treated with a silane-based modifier to improve its distribution in the host polymer. Atomic-force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, transmission electron microscopy, energy-dispersive x-ray spectroscopy, porosity and contact angle tests were conducted to characterize the properties of the particles as well as the fabricated nanocomposite membranes. The effects of the nanoparticle incorporation were evaluated by conducting ultrafiltration experiments. It was reported that the membrane pure water flux was increased with increasing NTiO2 loading owing to the high porosity of the nanoparticles embedded and/or formation of enlarged pores upon addition of them. The antifouling capacity of the membranes was also tested by ultrafiltration of bovine serum albumin fouling solution. It was found that both water flux and antifouling capacity tended to reach desired level if the NTiO2 added was at optimized loading.

Solvothermal synthesis of nanoporous TiO2: the impact on thin-film composite membranes for engineered osmosis application

In the current study, the impact of self-synthesized nanoporous titanium oxide (NT) on the morphology, performance and fouling of a polyamide (PA) thin-film composite (TFC) membrane was investigated when the membrane was applied for engineering osmosis (EO). The nanoporous structure and the spindle-like shape of NT were revealed through transmission electron microscopy (TEM), while the AATPS modification of NT was verified by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The results of x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) confirmed the presence of modified NT (mNT) in the PA dense active layer of the TFC membrane. The outgrowth of the 'leaf-like' structure, upon mNT loading, at the surface of the PA layer was observed by field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The TFC membrane prepared with 0.05 wt% mNT loading in the organic phase showed the water flux of 26.4 l m(-2) h(-1) when tested in the forward osmosis (FO) mode using 0.5M and 10 mM NaCl solution as the draw and feed solution, respectively. Moreover, the TFC-mNT membrane also demonstrated an intensified antifouling property against organic foulant during FO application and it was possible to retrieve the initial water flux almost completely with a simple water-rinsing process.

The effect of maternal hypothyroidism on cardiac function and tolerance to ischemia-reperfusion injury in offspring male and female rats

PURPOSE

Accumulating evidence indicates that intrauterine evolution disturbance can contribute to myocardial ischemia reperfusion (IR) injury; in addition, thyroid hormones (THs) have a crucial role in the development of different systems during fetal life. The aim of this study was to determine the effect of TH deficiency during fetal life on tolerance of isolated heart to ischemia during adulthood in both genders.

METHODS

Hypothyroidism was induced in pregnant Wistar rats by administrating 0.025 % 6-propyl-2-thiouracil in drinking water throughout pregnancy. Offspring of rats with maternal hypothyroidism (MH) and control groups were tested in adulthood. Isolated hearts were perfused with Langendorff setup and exposed to 30 min of ischemia, followed by 45 min of reperfusion. Baseline values of the left ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), heart rate (HR), and peak rates of positive and negative changes in left ventricular pressure (±dp/dt) were recorded.

RESULTS

In the MH groups the baseline levels of LVDP (male: 23 %, female: 33 %), HR (male: 31 %, female: 26 %), and ±dp/dt were significantly (p < 0.01) lower, compared to controls. After ischemia, hearts from male rats with MH had less tolerance to IR injury as assessed in terms of reductions in recovery of hemodynamic parameters compared to controls, while in female rats there were no significant differences between MH and controls.

CONCLUSIONS

MH decreases hemodynamic parameters in the heart of both male and female offspring in adulthood; in addition, hearts of male rats with MH show less tolerance to ischemia, compared to those of females.

Synthesis and characterization of novel thin film nanocomposite reverse osmosis membranes with improved organic fouling properties for water desalination

Incorporation of HNTs into PA layer improved not only the structural and separation characteristics of composite membrane but also its antifouling properties.

Nonlinear analysis of anesthesia dynamics by Fractal Scaling Exponent

The depth of anesthesia estimation has been one of the most research interests in the field of EEG signal processing in recent decades. In this paper we present a new methodology to quantify the depth of anesthesia by quantifying the dynamic fluctuation of the EEG signal. Extraction of useful information about the nonlinear dynamic of the brain during anesthesia has been proposed with the optimum Fractal Scaling Exponent. This optimum solution is based on the best box sizes in the Detrended Fluctuation Analysis (DFA) algorithm which have meaningful changes at different depth of anesthesia. The Fractal Scaling Exponent (FSE) Index as a new criterion has been proposed. The experimental results confirm that our new Index can clearly discriminate between aware to moderate and deep anesthesia levels. Moreover, it significantly reduces the computational complexity and results in a faster reaction to the transients in patients' consciousness levels in relations with the other algorithms.

Dimensional characterization of anesthesia dynamic in reconstructed embedding space

The depth of anesthesia quantification has been one of the most research interests in the field of EEG signal processing and nonlinear dynamical analysis has emerged as a novel method for the study of complex systems in the past few decades. In this investigation we use the concept of nonlinear time series analysis techniques to reconstruct the attractor of anesthesia from EEG signal which have been obtained from different hypnotic states during surgery to give a characterization of the dimensional complexity of EEG by Correlation Dimension estimation. The dimension of the anesthesia strange attractor can be thought of as a measure of the degrees of freedom or the ;complexity' of the dynamics at different hypnotic levels. The results imply that for awaked state the correlation dimension is high, On the other hand, for light, moderate and deep hypnotic states these values decrease respectively; which means for anesthetized situation we expect lower correlation dimension.

Optimization of MPEG-2 SNR scaleable codecs

It is shown how the signal-to-noise (SNR) scaleable coder can benefit from optimizing quantified discrete cosine transform (DCT) coefficients, in a rate-distortion context, in order to reduce bit-rate overheads. The technique is based on adjusting the quantized coefficients rather than dropping them, since the former gives finer control over rate-distortion trade-offs. The widely used Lagrangian optimization technique is then applied to arrive at the optimally adjusted coefficients block. We show that such an optimization is very efficient for the second layer, but has little effect on the base layer.

A successive approximation vector quantizer for wavelet transform image coding

A coding method for wavelet coefficients of images using vector quantization, called successive approximation vector quantization (SA-W-VQ) is proposed. In this method, each vector is coded by a series of vectors of decreasing magnitudes until a certain distortion level is reached. The successive approximation using vectors is analyzed, and conditions for convergence are derived. It is shown that lattice codebooks are an efficient tool for meeting these conditions without the need for very large codebooks. Regular lattices offer the extra advantage of fast encoding algorithms. In SA-W-VQ, distortion equalization of the wavelet coefficients can be achieved together with high compression ratio and precise bit-rate control. The performance of SA-W-VQ for still image coding is compared against some of the most successful image coding systems reported in the literature. The comparison shows that SA-W-VQ performs remarkably well at several bit rates and in various test images.

On the performance of linear phase wavelet transforms in low bit-rate image coding

The behavior of linear phase wavelet transforms in low bit-rate image coding is investigated. The influence of certain characteristics of these transforms such as regularity, number of vanishing moments, filter length, coding gain, frequency selectivity, and the shape of the wavelets on the coding performance is analyzed. The wavelet transforms performance is assessed based on a first-order Markov source and on the image quality, using subjective tests. More than 20 wavelet transforms of a test image were coded with a product code lattice quantizer with the image quality rated by different viewers. The results show that, as long as the wavelet transforms perform reasonably well, features like regularity and number of vanishing moments do not have any important impact on final image quality. The influence of the coding gain by itself is also small. On the other hand, the shape of the synthesis wavelet, which determines the visibility of coding errors on reconstructed images, is very important. Analysis of the data obtained strongly suggests that the design of good wavelet transforms for low bit-rate image coding should take into account chiefly the shape of the synthesis wavelet and, to a lesser extent, the coding.

Layered image coding using the DCT pyramid

A block-based subband image coder that exploits the ability to perform decimation in the discrete cosine transform (DCT) domain to effect a pyramidal data structure is described. The proposed "DCT pyramid" has a distinct feature of improved image rendition properties without the associated blocking artifacts at low bit-rates.

Modeling and subjective assessment of cell discard in ATM video

Measurements of subjective picture impairment as a function of network loading in a simulated ATM network are reported. The simulation indicated that cells tend to be discarded in bursts, the frequency and severity of which can be related to the loading by a threshold model. The effect of the discards on broadcast-style video, coded using a single-layer H.261-type method, was found to be a function of scene content and movement at the instant of occurrence. If the visibility of cell discards is maintained at or below threshold in worst-case scenes, the study indicated that network loadings around 55% for a multiplex of 16 video sources and around 70% for a multiplex of 48 video sources are achievable.