Identification of levomenthol derivatives as potential dipeptidyl peptidase-4 inhibitors: a comparative study with gliptins.

Dipeptidyl peptidase-4 (DPP4) inhibitors are a potent therapeutic treatment for type 2 diabetes mellitus (T2DM). There is a family of compounds used as DPP4 inhibitors (DPP4Is) called gliptins. They bind tightly to DPP4 to form an inactive protein-ligand complex. However, there remains a need to identify novel DPP4Is that are more efficacious and safer due to the increasing prevalence of T2DM and the undesirable side effects of gliptins. To identify potential DPP4Is, we screened over 1800 novel compounds in a comparative study with gliptins. We performed dual-factor molecular docking to assess the binding affinity of the compounds to DPP4 and found four compounds with a higher binding affinity to DPP4 than currently used gliptins. The newly identified compounds interacted with the dyad glutamate (GLU205 and GLU206) and tyrosine (TYR662 and TYR666) residues in DPP4's active site. We performed molecular dynamics simulations to determine the stability of the protein-ligand complexes formed by the compounds and DPP4. Furthermore, we examined the toxicity and pharmacological profile of the compounds. The compounds are drug-like, easy to synthesize, and relatively less toxic than gliptins. Collectively, our results suggest that the novel compounds are potential DPP4Is and should be considered for further studies to develop novel antidiabetics.Communicated by Ramaswamy H. Sarma.

Neonatal necrotizing enterocolitis due to COVID-19. A case report.

Digestive symptoms have been reported in an important proportion of children with COVID-19, and the clinical expression of critical patients with COVID-19 is thought to result from progressive increase of inflammation and an unusual trend of hypercoagulation. We report a newborn received with abdominal distension, green vomiting and imaging suggestive for enterocolitis. He had a close contact with COVID-19 and the PCR for SARS-CoV-2 came back positive. Despite the supportive measures, his condition deteriorated and a surgery was decided. The surgical exploration found an ischemic bowel. The therapeutic measures were ineffective as the child passed away a few hours after surgery despite the resuscitation treatment performed. The confirmed enterocolitis happening within the period of acute infection by SARS-CoV-2, the NEC was likely a manifestation of COVID-19.

Enhancing performance of WDM-RoFSO communication system utilizing dual channel technique for 5G applications.

In this work, the performance of wavelength division multiplexing based radio over free space optics (WDM-RoFSO) communication system is investigated utilizing OptiSystem 0.7 software. Four weather conditions are adopted in this paper, namely, clear, haze, rain and fog with attenuation losses of 0.2 dB/km, 2.3 dB/km, 4.3 dB/km and 8 dB/km, respectively In addition, a high radio frequency of 30 GHz with high bit rate of 160 Gbps is modulated and carried on optical signal for fifth generation (5G) applications. The dual channel technique is employed in order to enhance the performance parameters of proposed WDM-RoFSO communication system. The enhancement in the link range is about; 46.1%, 35%, 29.4% and 25.9% for clear, haze, rain and fog, respectively.

Collection, genotyping and virus elimination of cassava landraces from Tanzania and documentation of farmer knowledge.

Cassava (Manihot esculenta Crantz.) has been a vital staple and food security crop in Tanzania for several centuries, and it is likely that its resilience will play a key role in mitigating livelihood insecurities arising from climate change. The sector is dominated by smallholder farmers growing traditional landrace varieties. A recent surge in virus diseases and awareness in the commercial potential of cassava has prompted a drive to disseminate improved varieties in the country. These factors however also threaten the existence of landraces and associated farmer knowledge. It is important that the landraces are conserved and utilized as the adaptive gene complexes they harbor can drive breeding for improved varieties that meet agro-ecological adaptation as well as farmer and consumer needs, thereby improving adoption rates. Here we report on cassava germplasm collection missions and documentation of farmer knowledge in seven zones of Tanzania. A total of 277 unique landraces are identified through high-density genotyping. The large number of landraces is attributable to a mixed clonal/sexual reproductive system in which the soil seed bank and incorporation of seedlings plays an important role. A striking divergence in genetic relationships between the coastal regions and western regions is evident and explained by (i) independent introductions of cassava into the country, (ii) adaptation to prevailing agro-ecological conditions and (iii) farmer selections according to the intended use or market demands. The main uses of cassava with different product profiles are evident, including fresh consumption, flour production, dual purpose incorporating both these uses and longer-term food security. Each of these products have different trait requirements. Individual landraces were not widely distributed across the country with limited farmer-to-farmer diffusion with implications for seed systems.

Bronchopleural fistula in a 5- years old child with novel CARMIL 2 mutation: A rare disease and a rare case.

A five year girl had eczema and allergic rhinitis in the past, presented with a history of cough, shortness of breath for the last one month. Her chest -X-ray showed a left side pleural effusion, and a computed tomographic scan (CT) of the chest showed left side hydropneumothorax. Left side 21 Fr drain was inserted. Her clinical condition deteriorated despite antimicrobial therapy, and she required mechanical ventilatory support due to respiratory distress. She also developed a right-sided pneumothorax that was managed by inserting a 21 Fr chest drain. A video-assisted thoracoscopic VATS procedure was done to staple the lung bullae and drain the empyema. Her post-operative chest X-ray showed good lung expansion. Pleural fluid culture report was positive for candida. She was commenced on antifungal microbial therapy. Two days later, she developed again left side pneumothorax, which was again managed by left intercostal drain. We were unable to wean her off from mechanical ventilatory support due to a significant air leak due to bronchopleural fistula. A posterolateral thoracotomy was performed, and the bronchopleural fistula was closed. She was extubated the next day, and intercostal drains were removed on the 4th post-operative day.

Wideband full double-pass serial hybrid fiber amplifier utilizing L-shape configuration.

In this work, a new, to the best of our knowledge, full double-pass serial hybrid fiber amplifier is simulated on OptiSystem 7.0 software. A wideband flat gain spectrum covered both conventional and long communication bandwidth (C+L) from 1530 to 1590 nm, which is approximately 60 nm with high average gain of 23.6 dB; acceptable noise figure of 7 dB is achieved via the L-shape configuration. The main innovative step in the proposed design is decreasing the cascading amplification effect between the combined amplifiers, by making the individual full double-pass for the input signal in each amplifier stage.

Flexural Creep Behavior of High-Density Polyethylene Lumber and Wood Plastic Composite Lumber Made from Thermally Modified Wood.

The use of wood plastic composite lumber as a structural member material in marine applications is challenging due to the tendency of wood plastic composites (WPCs) to creep and absorb water. A novel patent-pending WPC formulation that combines a thermally modified wood flour (as a cellulosic material) and a high strength styrenic copolymer (high impact polystyrene and styrene maleic anhydride) have been developed with advantageous viscoelastic properties (low initial creep compliance and creep rate) compared with the conventional WPCs. In this study, the creep behavior of the WPC and high-density polyethylene (HDPE) lumber in flexure was characterized and compared. Three sample groupings of WPC and HDPE lumber were subjected to three levels of creep stress; 7.5, 15, and 30% of the ultimate flexural strength (Fb) for a duration of 180 days. Because of the relatively low initial creep compliance of the WPC specimens (five times less) compared with the initial creep compliance of HDPE specimens, the creep deformation of HDPE specimens was six times higher than the creep deformation of WPC specimens at the 30% creep stress level. A Power Law model predicted that the strain (3%) to failure in the HDPE lumber would occur in 1.5 years at 30% Fb flexural stress while the predicted strain (1%) failure for the WPC lumber would occur in 150 years. The findings of this study suggest using the WPC lumber in structural application to replace the HDPE lumber in flexure attributable to the low time-dependent deformation when the applied stress value is withing the linear region of the stress-strain relationship.

Structural Performance of HDPE and WPC Lumber Components Used in Aquacultural Geodesic Spherical Cages.

Based on previous research, a novel wood-plastic composite (WPC) lumber has shown potential to replace high-density polyethylene (HDPE) lumber in the construction of aquacultural geodesic spherical cage structures. Six HDPE and six WPC assemblies, which are representative of typical full-size cage dimensions, were fabricated by bolting pairs of triangular panel components made with connected struts. Half of the panel assemblies had a plastic-coated steel wire mesh to simulate the actual restraint in field applications of the cages. The objective of the research was to characterize the structural performance of the panel assemblies under compressive loading. To determine the critical buckling load for the panel assemblies made from WPC and HDPE struts with and without wire mesh, Southwell's method was implemented. A two-dimensional (2D) linear finite element analysis model was developed to determine axial forces in the struts of the panel assembly for the applied load and boundary conditions. This model was used to determine strut compressive forces corresponding to the Southwell's method buckling load and the experimental failure load. It was found that the wire mesh increased the load capacity of both HDPE and WPC panel assemblies by a factor of two. The typical failure mode of the panels made from HDPE lumber struts, with and without wire mesh, was buckling of the struts, whereas the failure mode of the WPC panels, with and without wire mesh, was fracture at the notched section corresponding to the location of the bolts. The load capacity of the panel assemblies made from WPC lumber struts was three times and 2.5 times higher than the load capacity of the panel assemblies made from HDPE lumber struts with and without wire mesh, respectively.

A new method for assessment of sediment-associated contamination risks using multivariate statistical approach.

This paper presents the assimilation of heavy metal concentration data from sequential extraction method (SEM) with metal toxicity factors to develop and propose two new sediment quality indices modified hazard quotient (mHQ) and ecological contamination index (ECI), to predict the potential ecological risks associated with sediment contamination. Chemical speciation data of five heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and lead (Pb) from five coastal aquatic ecosystems of the Equatorial Atlantic Ocean were used in the assessment of the degree of heavy metal contamination. Evaluation based on ECI indicated that sediments of most aquatic ecosystems were considerably to highly contaminated. The results showed that the proposed indices are reliable, precise, and in good agreement with similar existing indices used for evaluating the severity of sediment-associated contamination by heavy metals. The principal component analysis (PCA) and factor analysis indicated that heavy metals in the benthic sediments were mostly from anthropogenic sources. •New indices - modified hazard quotient (mHQ) and ecological contamination index (ECI) - were developed for predicting sediment-associated risk adverse effects.•Newly proposed indices agree closely with the existing pollution indices.•Pollution indices reveal significant anthropogenic contamination by Cd and Pb.

Quantitation of multiple mycotoxins and cyanogenic glucosides in cassava samples from Tanzania and Rwanda by an LC-MS/MS-based multi-toxin method.

A multi-mycotoxin method based on liquid chromatography/tandem mass spectrometry (LC-MS/MS) was used for a mycotoxin survey in 627 samples of processed cassava collected from different districts across Tanzania and Rwanda after the method performance for this matrix had been determined. Matrix effects as well as extraction efficiencies were found to be similar to most other previously investigated matrices with the exception of distinct matrix effects in the negative ionisation mode for early eluting compounds. Limits of detection were far below the regulatory limits set in the European Union for other types of commodities. Relative standard deviations were generally lower than 10% as determined by replicates spiked on two concentration levels. The sample-to-sample variation of the apparent recoveries was determined for 15 individually spiked samples during three different analytical sequences. The related standard deviation was found to be lower than 15% for most of the investigated compounds, thus confirming the applicability of the method for quantitative analysis. The occurrence of regulated mycotoxins was lower than 10% (with the exception of zearalenone) and the related limits were exceeded only in few samples, which suggests that cassava is a comparatively safe commodity as regards mycotoxins. The most prevalent fungal metabolites were emodin, kojic acid, beauvericin, tryptophol, 3-nitropropionic acid, equisetin, alternariol methylether, monocerin, brevianamide F, tenuazonic acid, zearalenone, chrysophanol, monilifomin, enniatins, apicidin and macrosporin. The related concentrations exceeded 1 mg kg(-1) only in few cases. However, extremely high levels of cyanogenic plant toxins, which had been previously added to the method, were observed in few samples, pointing out the need for improved post-harvest management to decrease the levels of these compounds.

Enhancing performance of multiwavelength Brillouin-Raman fiber laser by capturing residual pump power.

We demonstrate a simple design to enhance the performance of a multiwavelength Brillouin-Raman fiber laser by capturing the residual Raman pump power (RPP) from the laser cavity using a wavelength-selective coupler. The performance parameters of the laser system are investigated and compared with the conventional design under the same input design parameters. Both laser systems at a RPP of 375 mW can generate up to 33 Stokes lines with an equal channel spacing of 0.08 nm; however, the tunability of the laser without injection of residual RPP is 25% higher than the conventional laser structure. In addition, for a laser system without residual RPP injection, increasing the RPP improves the laser performance and generates up to 42 Stokes lines with a tunability of 24.5 nm, from 1570 to 1594.5 nm, at 475 mW. In contrast, the laser system with a residual RPP has the worst performance as the pump power is increased, and generates only nine Stokes lines with a tuning range of 5 nm at the same RPP of 475 mW.

Characteristics of multiwavelength L-band Brillouin-Raman fiber laser under forward and backward pumped environment.

We experimentally investigate the performance of L-band multiwavelength Brillouin-Raman fiber laser (MBRFL) under forward and backward pumped environments utilizing a linear cavity. A short length of 1.18 km dispersion compensating fiber is used as a nonlinear gain medium for both Brillouin and Raman gain. Experimental results indicate that the gain in the copumped laser configuration is higher than the gain in the counterpumped configuration. A stable and constant number of Brillouin Stokes lines up to 23 Stokes, with channel spacing of 0.08 nm and more than 20 dB of optical signal to noise ratio, can be generated as well as tuning over 20 nm in the L-band region from 1570 to 1590 nm. The laser generating the Brillouin Stokes lines exhibits flat amplitude bandwidth and high average output power of 0.8 and 1.6 dBm for the copropagation and counterpropagation pumps, respectively. Moreover, the tuning range bandwidth of the MBRFL can be predicted from the oscillated Brillouin pump gain profile.

Histolopathological patterns of cervical carcinoma seen at a radiotherapy centre in Ibadan, Nigeria.

BACKGROUND: The treatment of cervical carcinoma is dependent on many factors including histological types and degree of differentiation. Degree of differentiation is an important consideration in determining the prognostic outcome. OBJECTIVE: The study investigates the histological pattern and grades of cervical cancer tumours seen at a radiotherapy centre in Ibadan, Nigeria. PATIENTS AND METHOD: This retrospective study was carried out within Radiotherapy Department of University College Hospital, Ibadan. The records of patients diagnosed of cervical cancer seen between July 2008 and June 2010 were analysed. Data pulled out included age, disease stage at presentation, histological variant and degree of differentiation. RESULTS: 206 patients were seen during the period of which 196 had complete data. Squamous cell carcinoma (SCC) was seen in 178 patients (i.e. 90.8%) while 14 patients (7.1%) had adenocarcinoma. One patient each had adenoid cystic carcinoma, adenosquamous carcinoma, clear cell carcinoma and mucinous carcinoma. Majority of the patients, 99 (50.5%) had poorly differentiated tumours, 64 (32.7%) had well differentiated tumours, while the rest 33 (16.8%) had moderately differentiated tumours. Of the SCC tumours, 95 (53.4%) were poorly differentiated, 58 (32.6%) well differentiated while the remaining 25 (14%) were moderately differentiated. In comparison only 3 of the 14 adenocarcinoma cases (21.4%) were poorly differentiated, 5 cases (35.7%) were well differentiated, while 6 (42.9%) were moderately differentiated. The difference in the degree of differentiation between squamous histology and adenocarcinoma was statistically significant (p value = 0.002). CONCLUSION: Poorly differentiated squamous cell carcinoma remains the leading variants of cervical cancer seen in our environment.

Distribution of polycyclic aromatic hydrocarbons in surface soils and water from the vicinity of Agbabu bitumen field of Southwestern Nigeria.

Water and soil samples from the vicinity of Agbabu bitumen field of Southwestern Nigeria, were analyzed qualitatively and quantitatively for 10 parent polycyclic aromatic hydrocarbons (PAHs) using gas chromatography coupled by flame ionization detector (GC-FID), in order to gather information on the degree of contamination by bitumen exploration and processing in this area. The total concentrations of 10 PAHs varied from 11.2 to 341.5 microg L(- 1) in water and from 101.5 to 209.7 ng g(- 1) dry weight in soils. The total PAH levels in water samples from all the sampling stations (except at station WB 11), were sufficiently high (> 10 microg/L) to cause acute toxicity to the exposed organisms. Special PAH compound ratios, such as phenanthrene/anthracene and fluoranthene/pyrene, were calculated to evaluate the relative importance of different origins. The collected data indicate pyrolytic and petrogenic sources. The anthropogenic PAHs, i.e., pyrene and benzanthracene exhibited similar distribution patterns in the studied area, implying that these compounds possess identical sources. Also, dibenzothiophene, a sulfur heterocyclic aromatic compound was determined in this study and it was not detected in all the samples analyzed.

Hepatitis C virus infection in hemodialysis patients in Sudan: two centers' report.

Prevalence of HCV seropositivity among the hemodialysis population in Sudan is estimated to be around 34%. We undertook a cross sectional study in two major HD centers in Khartoum, Sudan for the prevalence of HCV seropositivity among the hemodialysis patients, during January to March 2005. Testing for HCV antibodies was performed using 3rd generation enzyme linked immunoadsorption assay (ELISA). A total of 236 patients were included in the study: 218 adults and 18 children. The mean age was 43.6 +/- 15.6 years, and the majority was males: 71.6%. The cause of renal failure was unknown in 168 patients (71.2%). The mean HD duration was 36.6 +/- 35.1 months. Prevalence of HCV seropositivity was 23.7%. Among 170 patients who were previously HCV seronegative, 30 (17.1%) seroconverted to positive in one year (estimated incidence: 63 new cases per year). HCV seropositivity was associated with longer duration of dialysis (p < 0.00001), previous surgery (p= 0.026), age of over 30 and years (p = 0.008), and dialysis in multiple centers (p= 0.005). We conclude that although HCV seropositivity in our study was lower than previously reported, it was still high among HD patients in Sudan. Nosocomial transmission of HCV among hemodialysis patients is a contributing factor.

Chemical and ecotoxicological assessment of polycyclic aromatic hydrocarbon--contaminated sediments of the Niger Delta, Southern Nigeria.

The extent of environmental contamination and sources of polycyclic aromatic hydrocarbons (PAHs) compounds to sediments of the Niger Delta, Nigeria were assessed using combined chemical analysis and toxicity bioassay techniques. Concentrations of two- to six-ring PAHs of molecular mass 128-278 and toxicity to Vibrio fischeri and Lemna minor are considered in this investigation. Levels of the sum of the 16 USEPA priority pollutant PAHs varied from 20.7 to 72.1 ng/g dry weight. Sediment PAH levels were highest in samples collected from Delta Steel located at the outskirts of Warri, and Quality control centre, Ughelli West; with total PAH concentrations of 72.1 and 67.5 ng/g dry weight, respectively. The overall levels of PAHs in this study are low compared to other regions and reveal moderate PAHs pollution in the sediments of the Niger Delta. Two- and three-ring aromatic hydrocarbons predominated in almost all the sediments, which indicate a petrogenic origin. The sediment total PAH (PAHtot) concentration, normalized to organic carbon content (OC), ranged from 120.2 to 1.99 ng PAHtot/mg OC; and showed distinctively that the sedimentary organic matter of the sample from Delta Steel is highly contaminated with PAHs, and had a value of 120.2 ng PAHtot/mg OC. The toxicity bioassays indicated that the sample collected from Warri Refinery Area (SDWRR) was the most toxic to V. fischeri, with an EC50 value of 0.45 mg sediment equiv./mL test medium; and samples from Ogunu (SDOGN) and Warri Refinery area (SDWRR) showed high toxicity to L. minor, with percent inhibitions of 42.6% and 33.67%, respectively, after 7 days of exposure. The total PAH concentrations showed no correlation with toxicity bioassays, and thereby implied that chemical analysis of PAHs cannot be an indicator of sediment toxicity.

Development of disposable amperometric sulfur dioxide biosensors based on screen printed electrodes.

The possibility of developing amperometric biosensors for the measurement of SO(2) in flowing gas streams has been examined. Screen-printed carbon electrodes (SPCEs) were tailored with the enzyme sulfite oxidase and cytochrome c and the response is generated through the resulting enzymatic and electrocatalytic reactions involving SO(3)(2-), formed when SO(2) gas is dissolved in the supporting electrolyte. Two methods of integrating the enzyme and cytochrome c with the SPCE were investigated. In one design (b-type biosensor), the components were mixed thoroughly with the same ink used to produce the SPCEs, then the modified ink was spread over the working electrode. In the second approach the bio-components were dissolved in the supporting electrolyte and simply deposited on top of the transducer (s-type biosensor). Both devices gave linear responses over the range 4--50 ppm but the sensitivity of the s-type was approximately twice that of the b-type biosensor. In addition, the time taken to reach 90% of the maximum response (t(90%)) was 110 s for the s-type biosensor compared with 200 s for the b-type biosensor. These studies illustrate the successful use of biosensors for the detection of sulfur dioxide at the relatively low potential of +0.3 V versus Ag.AgCl and should provide useful alternatives for decentralised environmental studies.

Malarial infection and birthweight in urban Zanzibar, Tanzania.

In urban Zanzibar, Tanzania, 389 women with full-term pregnancies were studied to see what effect their infection with malaria (at delivery) had on the birthweight (BW) of their infants. The overall prevalence of low birthweight (LBW) (i.e. < 2500 g) was 3.9% (15 out of 389). Overall, 21.3% (82/384) of the women only had peripheral parasitaemias at delivery, 17.6% (58/329) only had active placental infections and 47.9% (157/328) had both. The youngest women (< 20 years), the primiparae and those with Plasmodium infection gave birth to neonates with relatively low mean BW. The lowest mean BW (2967 g) was found among the offspring of women with active placental infection (N = 58). The women with past/chronic infection (N = 73) or no infection (N = 201) generally produced heavier infants, with mean BW of 3242 and 3338 g, respectively. The women with active placental infection were also far more likely to have babies of LBW (15.5%) than those with past/chronic infection (1.4%) or no infection (1.5%). Multivariate analysis indicated that the highest relative risk of LBW (10.1, with a 95% confidence interval of 2.9-35.4) was associated with active placental infection, with no significant difference between primiparae and multiparae. In the study population, therefore, with its low prevalence of LBW, malaria infection increased the risk of LBW in full-term neonates by about 10-fold, with a population-attributable proportion of 55.4%.

PIP: 389 pregnant women admitted for full- term, uncomplicated delivery at the Regional Hospital on the island of Zanzibar (Tanzania) were recruited to study the effect of malarial infection on birth weight in an endemic area. 3.8% of all newborns weighed less than 2500 g (i.e., low birth weight [LBW]). 21.4% of all women had peripheral parasitemias but no active placental infection. 17.6% had active placental infection but no peripheral parasitemia. 47.9% had both active placental and peripheral infections. Logistic regression analysis revealed that active placental infection was associated with LBW (15.5% vs. 1.2%; relative risk [RR] = 10.1, population attributable proportion [PAP] = 61.4%; p = 0.003). Serum albumin level less than 2.5 mg/dl was also associated with LBW (11.8% vs. 1.2%; RR= 10.2, PAP = 61.%; p = 0.008). Overall malarial infection was associated with LBW (6.5% vs. 1.8%; RR = 3.5; PAP = 55.4%; p = 0.04). These findings suggest that placental malaria causes intrauterine growth retardation, leading to LBW newborns and that malarial preventive interventions in pregnant women are needed in Tanzania.