Assessment of plant diversity of endemic species of the Saharo-Arabian region in Egypt

Savanna, semi-deserts, and hot deserts characterize the Saharo-Arabian region, which includes Morocco, Mauretania, Algeria, Tunisia, Libya, Egypt, Palestine, Kuwait, Saudi Arabia, Qatar, Bahrain, the United Arab Emirates, Oman, Yemen, southern Jordan, Syria, Iraq, Iran, Afghanistan, Pakistan, and northern India. Its neighboring regions, the Sudano-Zambezian region belonging to the Paleotropical Kingdom and the Mediterranean and Irano-Turanian regions included in the Holarctic Kingdom, share a large portion of their flora with the Saharo-Arabian region. Despite the widespread acknowledgment of the region's global importance for plant diversity, an up to date list of the Saharo-Arabian endemics is still unavailable. The available data are frequently insufficient or out of date at both the whole global and the national scales. Therefore, the present study aims at screening and verifying the Saharo-Arabian endemic plants and determining the phytogeographical distribution of these taxa in the Egyptian flora. Hence, a preliminary list of 429 Saharo-Arabian endemic plants in Egypt was compiled from the available literature. Indeed, by excluding the species that were recorded in any countries or regions outside the Saharo-Arabian region based on different literature, database reviews, and websites, the present study has reduced this number to 126 taxa belonging to 87 genera and 37 families. Regarding the national geographic distribution, South Sinai is the richest region with 83 endemic species compared with other eight phytogeographic regions in Egypt, followed by the Isthmic Desert(the middle of Sinai Peninsula, 53 taxa). Sahara regional subzone(SS1) distributes all the 126 endemic species, Arabian regional subzone(SS2) owns 79 taxa, and Nubo-Sindian subzone(SS3) distributes only 14 endemics. Seven groups were recognized at the fourth level of classification as a result of the application of the two-way indicator species analysis(TWINSPAN) to the Saharo-Arabian endemic species in Egypt, i.e., Ⅰ Asphodelus refractus group, Ⅱ Agathophora alopecuroides var. papillosa group, Ⅲ Anvillea garcinii group, Ⅳ Reseda muricata group, V Agathophora alopecuroides var. alopecuroides group, Ⅵ Scrophularia deserti group, and Ⅶ Astragalus schimperi group. It's crucial to clearly define the Saharo-Arabian endemics and illustrate an updated verified database of these taxa for a given territory for providing future management plans that support the conservation and sustainable use of these valuable species under current thought-provoking devastating impacts of rapid anthropogenic and climate change in this region.

Eco-toxicity and health risk assessment of polycyclic aromatic hydrocarbons in surface sediments of Burullus Lake in Egypt

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous environmental contaminants of growing concern due to their potential ecological and human health risks.This study presents a comprehensive assessment of PAHs contamination in the surface sediments of Burullus Lake,a vital and second largest delta lake in Egypt.The aim was to evaluate the eco-toxicity and potential health risks associated with the presence of these compounds.Surface seven sediment samples were collected from various drains in the southern part of Burullus Lake.Soxhlet extraction method was employed to extract PAHs(16PAHs)from the sediment sample.Analytically,target compounds were located using HPLC.The results showed that samples contained PAHs levels ranging from 0.038×10^(-6)to 0.459×10^(-6),which is considered heavily polluted by the European standard for PAHs pollution.Additionally,there was no apparent source of PAHs in the ElKhashah drain or the Brinbal Canal,as HPLC found none of the compounds.The most prevalent compound in sediment samples along the study area was fluoranthene.The diagnostic indices in the present study indicated that the hydrocarbons in the region originated from pyrolytic and man-made sources along the drains of Burullus Lake.The principal component analysis(PCA)and diagnostic ratios revealed that coal combustion and pyrolytic sources were responsible for the PAHs contamination in the surface sediments.The non-carcinogenic risk(HI),which is the product of the HQs for the adult and child populations,respectively,was calculated.HI values under 1,therefore,demonstrated that they had no carcinogenic effects on human health.TEQs and MEQs in the sediments of Burullus Lake do not have a cancer-causing impact on people.For the safety of nearby wildlife,aquatic life,and people,all activities that raise petroleum hydrocarbon levels in Burullus Lake must be adequately regulated and controlled.According to the ecological risk assessment,there is little chance that PAHs will be found in the sediments of Burullus Lake.This study underscores the urgent need for effective pollution control measures and regular monitoring of PAHs levels in Burullus Lake sediments to protect the aquatic ecosystem and public health.It also highlights the importance of considering eco-toxicity and human health risks in integrated risk assessments of PAHs-contaminated environments.

The global,prevalence,and risk factors of postoperative fever after percutaneous nephrolithotomy:A systematic review and meta-analysis

Objective:This study aimed to explore the global,prevalence,and risk factors of fever after percutaneous nephrolithotomy(PCNL)by conducting a systematic review and meta-analysis.Methods:The high-sensitivity searching was conducted without time limitation until December 30,2020 in Web of Sciences,Scopus,and PubMed based on inclusion and exclusion criteria.Results:The prevalence rates of fever and sepsis among patient undergoing PCNL were estimated 9.5%(95%confidence interval[CI]:9.3%-9.7%),and 4.5%(95%CI:4.2%-4.8%),respectively.Nephrostomy tube was used in 9.96%(95%CI:9.94%-9.97%)of patients.The mean preoperative white blood cells of patients were 6.401×109/L;18.3%and 4.55%of patients were considered as the positive urinary culture and pyuria,respectively.About 20.4%of patients suffered from residual stones.The odds ratios(ORs)of fever in patients who suffering from diabetes mellitus,hydronephrosis,staghorn stones,and blood transfusion were 4.62(95%CI:2.95-7.26),1.04(95%CI:0.81-1.34),2.57(95%CI:0.93-7.11),and 2.65(95%CI:1.62-4.35),respectively.Patients who underwent PCNL in prone position were more likely to develop fever(OR:1.23;95%CI:0.75-2.00)than patients in supine position.Conclusion:The current study showed that patients who suffer from diabetes mellitus,hydronephrosis,staghorn stones,nephrostomy tube or double-J stent,blood transfusion,and also patients who underwent PCNL in prone position surgery are more likely to develop a postoperative fever after PCNL.

First case of fungal keratitis secondary to Yamadazyma mexicana

Dear Editor,Fungal keratitis is a serious and potentially sightthreatening infection that poses a global health concern,with higher incidence rates reported in low-income countries and regions with tropical climates[1-3].Risk factors for fungal keratitis include trauma with vegetative matter,contact lens wear,history of ocular surgery,chronic topical steroid use,low socioeconomic status and tropical climate[1-2].Fungi have the propensity to penetrate deep into the corneal stroma,making the infection difficult to treat with topical antifungal agents alone.Complications such as corneal perforation and endophthalmitis can arise in severe cases,making early identification of the causative fungal pathogen of utmost importance[4-5].Moreover,obtaining susceptibilities to the available antifungal agents can be sight and eye saving[5].

Antibiotic Resistance Profile of Enterococcus faecalis and Enterococcus faecium Isolates from Urine and Pleural Fluid in Two Hospitals of Cameroon

Enterococcus faecalis and Enterococcus faecium rank among the leading causes of nosocomial bacteremia and urinary tract infections. They often persist on hospital surfaces due to their ability to withstand adverse environmental conditions (low or high temperatures, high pH, and high salinity). The global Enterococcus faecalis-Enterococcus faecium ratio is currently shifting towards Enterococcus faecium. Enterococci present variable levels of resistance to certain families of antibiotics. This is the case for aminoglycosides, beta-lactams and cephalosporins. In 2017, WHO ranked Enterococci among priority pathogens for research and development of new antibiotics. The objective of our study was to determine the antibiotic resistance profile of Enterococcus faecalis and Enterococcus faecium isolates from urine and pleural fluid in two hospitals in Cameroon. This cross-sectional and analytic study was carried out between June to August 2023 on hospitalized and day patients in which a cytobacteriological test of urine and pleural fluid was done. The samples were inoculated on CLED Agar for urine and on Chocolate + polyvitex and blood agar (prepared from Columbia agar) for pleural fluid samples and incubated at 37℃ for 18 to 24 hours. Identification of isolates was carried out using the API 20 STREP micro gallery (Biomerieux, France) and tested for antimicrobial susceptibility. The data on socio-demographical and potential risk factors were recorded using self-administered questionnaires and data from laboratory analyses of the specimen were collected in a data capture sheet. Potential risk factors associated with the presence of Enterococci, were evaluated using the logistic regression in univariate and multivariate analysis. P value < 0.05 was considered as significant. A total of 511 patients were recruited who were predominantly females. Enterococcus spp were isolated in 27.79% of our samples with Enterococcus faecalis mostly encountered. Enterococcus spp showed a high level of resistance to penicilline (99.3% to Ampicilline), macrolides (66.2% to Erythromycin) and cyclines (85.2% to Doxycycline). Hospitalisation, access to health facilities, contact with urine specimen and hand hygiene practices were risk factors related to infection with Enterococcus spp while hospitalisation, health facility and hand hygiene were related to glycopeptide resistant Enterococcus. Strict compliance with hygiene rules and appropriate antibiotic consumption could help in the fight against these infections.

Incidence, risk factors and clinical outcome of multidrug-resistant organisms after heart transplantation

BACKGROUND Transplant recipients commonly harbor multidrug-resistant organisms(MDROs),as a result of frequent hospital admissions and increased exposure to antimi-crobials and invasive procedures.AIM To investigate the impact of patient demographic and clinical characteristics on MDRO acquisition,as well as the impact of MDRO acquisition on intensive care unit(ICU)and hospital length of stay,and on ICU mortality and 1-year mortality post heart transplantation.METHODS This retrospective cohort study analyzed 98 consecutive heart transplant patients over a ten-year period(2013-2022)in a single transplantation center.Data was collected regarding MDROs commonly encountered in critical care.RESULTS Among the 98 transplanted patients(70%male),about a third(32%)acquired or already harbored MDROs upon transplantation(MDRO group),while two thirds did not(MDRO-free group).The prevalent MDROs were Acinetobacter baumannii(14%),Pseudomonas aeruginosa(12%)and Klebsiella pneumoniae(11%).Compared to MDRO-free patients,the MDRO group was characterized by higher body mass index(P=0.002),higher rates of renal failure(P=0.017),primary graft dysfunction(10%vs 4.5%,P=0.001),surgical re-exploration(34%vs 14%,P=0.017),mechanical circulatory support(47%vs 26%P=0.037)and renal replacement therapy(28%vs 9%,P=0.014),as well as longer extracorporeal circulation time(median 210 vs 161 min,P=0.003).The median length of stay was longer in the MDRO group,namely ICU stay was 16 vs 9 d in the MDRO-free group(P=0.001),and hospital stay was 38 vs 28 d(P=0.006),while 1-year mortality was higher(28%vs 7.6%,log-rank-χ2:7.34).CONCLUSION Following heart transplantation,a predominance of Gram-negative MDROs was noted.MDRO acquisition was associated with higher complication rates,prolonged ICU and total hospital stay,and higher post-transplantation mortality.

Screening of Rodents from Rural Communities of Lagos and Ogun State Nigeria of Lassa Virus RNA

Background: In recent times, there has been an increase in the number of Lassa fever cases resulting from the several episodes of Lassa fever epidemics ravaging Nigeria and other West African countries. The presence of Lassa virus in rodents other than the major reservoir (Mastomys natalensis) has been a public health concern as to the actual burden of the disease. It is therefore of a public health necessity to explore the LASV RNA habouring potential of several species of rodents in endemic as well as non-endemic areas for proper prevention of emergence of outbreaks in non-endemic areas. Objectives: The aim of this study was to detect the presence of LASV RNA in different species of rodents in Ikorodu, Lagos state and Abeokuta, Ogun state. Methods: A total of ninety one (91) rodents were captured from Ikorodu, Lagos State (61 rodents) and Abeokuta, Ogun State (30 rodents), euthanized, bled, and plasma obtained for the detection of LASV RNA by Reverse Transcriptase Polymerase Chain Reaction. Results: A total of 91 rodents consisting of 77 Rattus rattus and 14 Crocidura spp. The S segment of LASV RNA was not in any of the 91 rodents’ plasma samples. Conclusion: The rodents captured within the rural communities of Ikorodu, Lagos State and Abeokuta, Ogun State were found not to habour the LASV RNA. This study is limited by the relatively small sample size. Similar studies should be encouraged both in endemic and non-endemic areas in order to understand the actual burden of Lassa fever as well as put into check future epidemics.

Combined Application of Biostimulants and EDTA Improved Wheat Productivity under Cadmium Stress

Wheat(Triticum aestivum L.)exhibits a greater capacity for cadmium(Cd)absorption compared to other cereal crops,leading to elevated daily Cd intake,and posing a significant threat to public health.For the mitigation of Cd stress in sustainable and environmentally friendly way,a pot study was designed by using exogenous application of various biostimulants,i.e.,Nigella sativa and Ocimum sanctum extracts:0%,10%,and 20%in combination with the chelating agent ethylenediaminetetraacetic acid(EDTA)using 0 and 5 mg kg^(-1) under various levels of Cd stress(i.e.,0,5,10,and 15 mg kg^(-1) soil).Results revealed that Cd stress significantly reduced the seed emergence,growth,root,and allometric characters and yield-related parameters of wheat crops.The most observable reduc-tion was documented in wheat plants exposed to a higher Cd concentration(15 mg kg^(-1)),followed by the lower Cd level(control).The combined application of bio-stimulants and EDTA minimized the negative impacts of Cd stress.The highest increase in seedling emergence(5.44%),leaf area(50.60%),number of tillers(31.02%),grain yield per plant(24.28%),biological yield(13.97%),and decrease in Cd levels in grains(40%)was noticed where 20%foliar application of N.sativa and 10%of O.sanctum biostimulants were done using 5 mg kg^(-1) of soil-applied EDTA.This intervention demonstrated a notable reduction in Cd-induced negative effects,highlighting the potential of these substances in promoting sustainable wheat cultivation in contaminated environments.Moreover,it is an eco-friendly and approachable method at thefield level able to ensure food safety.

Radiographic Equipment and Accessories as a Potential Source of Nosocomial Infection

Background: Nosocomial infections have become a major challenge in healthcare facilities as they affect the quality of medical care. Radiological imaging plays a crucial role in medical diagnosis. However, the equipment and accessories used increase the risk of transmission of nosocomial bacteria. Objective: This study aims to reveal the extent and nature of microbiological contamination in four hospital diagnostic imaging departments to determine their potential role in the spread of nosocomial bacteria and to evaluate the effectiveness of routine daily disinfection practices in controlling microorganisms in diagnostic imaging departments. Methods & Results: In each department, swabs were taken from the surfaces of selected parts of the equipment and accessories three times a day (early morning, noon, and evening) for five consecutive days. Bacteria were isolated from 65 swabs (36.1% of all samples). The bacteria were isolated 3 times (4.6%) in the morning, 16 times (24.6%) at midday, and 46 times (70.7%) in the evening. The bacteria isolated were Escherichia coli (isolated 34 times;52.3%), Staphylococcus aureus (20 times;30.8%), Staphylococcus epidermidis (6 times;9.3%), and Klebsiella species (5 times;7.7%). Discussion & Conclusion: Findings demonstrated that radiology equipment and accessories are not free of bacteria and further improvements in the sterilization and disinfection of radiology equipment and accessories are needed to protect staff and patients from nosocomial infections.

Gastrointestinal Ulcers Treatment: Plants and Recipes Used by Herbalists of Abomey-Calavi and Cotonou Districts, Southern Benin

This study set out to identify plants and recipes used by herbalists in the municipalities of Abomey-Calavi and Cotonou to treat gastrointestinal ulcers and to characterize the distribution of their knowledge. An ethno-pharmacological survey was carried out in which informants who agreed freely were interviewed using a semi-structured questionnaire. A total of 85 herbalists were surveyed. The data were processed with Microsoft Excel to calculate the relative frequencies of citation of the various species mentioned by the herbalists and various indices including Simpson’s Index were adapted to test the distribution of their knowledge. Multiple regression and correspondence analysis were performed using R studio. Our results revealed that the Dendi, Ifè and Mina, all equitable in their knowledge of anti-ulcer plants, are likely to know more than the other ethnic groups. On the other hand, respondents practicing Islam are more likely to know many antiulcer plants than those practicing Vodoun and Christianity. This constant distribution of knowledge of anti-ulcer plants among the Dendi, Ifè and Mina, three different ethnic groups seems normal and attests to the fusion between these different ethnic groups in view of this knowledge. A total of 70 anti-ulcer recipes, made from 71 species of medicinal plants or non-floristic resources were recorded. Vitellaria paradoxa, Parkia biglobosa and Ocimum gratissimum were the top 03 most frequently cited in descending order of frequency. All the species cited are grouped into 44 botanical families among which the Fabaceae, Lamiaceae and Sapotaceae were strongly represented. Benin’s flora abounds in a diversity of medicinal plant species known to herbalists in Abomey-Calavi and Cotonou for the treatment of gastrointestinal ulcers. The results of this study constitute a good archive for the selection of plant species for in-depth studies with a view to formulating improved traditional medicines for gastrointestinal ulcers.

Evaluating the Association between Human Papillomavirus and Vulvar Cancer:A Comprehensive Analysis Using Bradford Hill Criteria

Background:The role of human papillomavirus(HPV)in the development of vulvar cancer(VC)has been widely studied,but findings have been inconsistent.Despite numerous meta-analyses exploring the potential link between HPV and VC,the association remains controversial due to inherent limitations in meta-analytic methods.Objectives:To address this controversy,the study aims to investigate the potential link between HPV and VC using the Bradford Hill criteria,which offer a more comprehensive framework for establishing causation.Methodology:The study began by extracting all relevant studies on the association between HPV and VC from the PubMed database.The potential links were then assessed by examining the data using the major postulates of the Bradford Hill criteria.To ensure the reliability of the findings,the methodologies of the identified studies were critically evaluated to account for possible false-negative and false-positive results.Results:The assessment of previous studies against the Bradford Hill criteria revealed that the major postulates were not fulfilled.Conclusion:Based on the findings,it can concluded that there is no causal association between HPV and VC.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Coinfection with Malaria in Selected States in Nigeria

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Plasmodium species are the causative agents of coronavirus disease 2019 (COVID-19) and malaria respectively with similar clinical presentations. The objective of this study is to determine the burden of co-infection of SARS-CoV-2 and malaria in the general population. Five (5 mLs) of blood samples were collected for SARS-CoV-2 and malaria parasite test. The malaria test was performed using a commercially available one-step malaria antigen Plasmodium falciparum histidine-rich protein 2 (Pf HRP-II) rapid test kit. The results of the study showed that the participants that were coinfected with SARS-CoV-2 IgG and malaria were 13 (2.5%) in Lagos, 1114 (39.1%) in Delta and 49 (2.3%) in Sokoto States. The prevalence of coinfection of SARS-CoV-2 and malaria in urban areas in Lagos, Delta and Sokoto States were 7 (2.2%), 1373 (48.1%), and 5 (0.2%) respectively. In rural areas, the prevalence of coinfection of SARS-CoV-2 and malaria in Lagos, Delta and Sokoto States were 6 (0.3%), 365 (12.8%), and 44 (2.1%) respectively in this study. This suggests that participants in the urban areas were more prone to co-infections than the rural areas in Lagos and Delta states, while it was otherwise in Sokoto State. In conclusion, the co-infection of SARS-CoV-2 and malaria was very high in Delta State compared to the other States. It is important for clinics to screen for both diseases when patients present with symptoms of malaria. This is because the infections have similar symptoms and the public is quick to assume malaria infection without diagnosing for COVID-19 and vice versa.

Safety and in Vivo Anti-Inflammatory Activity of Ethanolic Extract of Ficus umbellata (Vahl.) Leaves

Toxicity is the totality of adverse effects, which can be functional and morphological lesions in a living organism, caused by a substance introduced in relatively high single doses or in small, repeated doses. The aim of this study was to assess the OECD-recommended acute oral toxicity and anti-inflammatory activity of ethanolic extract of Ficus umbellata leaves. Animals were given a single oral dose of 1000, 3000 and 5000 mg/Kg body weight (BW) of the extract. For the anti-inflammatory activity test, rats were given the ethanolic extract of F. umbellata leaves at doses of 100, 300 and 500 mg/Kg or aspirin® at a concentration of 100 mg/Kg PC orally, one hour before injection of 0.05 ml of 1% formalin under the plantar fascia of the rat’s right hind paw. Paw volume measurements were taken one, two and three hours after formalin injection, using an electronic caliper. After 14 days of observation, no deaths were observed in treated rats. The LD50 of ethanolic extract of Ficus umbellata leaf powder is greater than 5000 mg/Kg body weight. This extract has no significant effects on hematological parameters and on the main markers of nephrotoxicity and hepatotoxicity for a single dose of less than 5000 mg/Kg PC. It reduces formalin-induced edema. Evaluation of the percentage inhibition showed that the extract had greater anti-inflammatory activity at 3 hours after the start of the experiment. However, better inhibition of inflammatory oedema of the paw of rats treated with 500 mg/Kg was observed at 5 hours after the start of the experiment, with a percentage inhibition of 69.23 ± 1.02, compared with the reference group treated with aspirin® 100 mg/Kg, which showed an inhibition of 63.50 ± 0.98. These results show that F. umbellata leaves possess anti-inflammatory activity, which would justify their use in traditional African medicine to prevent or treat inflammation.

Modulation of the in vitro Oxidative Stress and Erythrocyte Cell Membrane Integrity Using Aqueous, Hydroethanolic and Ethanolic Stem-Barks Extracts of Greenwayodendron suaveolens (Engl. & Diels) Verdc

Pneumonia, a respiratory infection induces acute or chronic inflammation, characterized by increased activity of lymphocytes and neutrophils, thus generating oxygen-free radicals that decrease the endogenous antioxidants defence system. The aim of this experimental study focused on the capacity of nontoxic aqueous, hydroethanolic and ethanolic extracts of Greenwayodendron suaveolens (Engl. & Diels) Verdc. subsp. suaveolens to regulate free reactive species and protein inflammation generated by infectious disease. The phytochemical screenings of G. suaveolens extracts were carried out according to precipitation and colorimetric methods. The total antioxidant and flavonoid contents were determined by the Folin-Ciocalteu and Aluminium Chloride ethanolic methods. The efficiency of G. suaveolens extracts on free radicals was evaluated using DPPH•, ABTS+•, and FRAP methods. The anti-inflammatory properties of extracts were evaluated according to in vitro protein (BSA) denaturation, Proteinase Inhibitory Action, and Red Blood Cell Membrane stabilization assays. The G. suaveolens aqueous, hydroethanolic and ethanolic extracts were used for the acute toxicity assessment according to the OECD protocol. The obtained results showed the presence of flavonoids, phenols, polyphenols, tannins, anthocyanins, alkaloids, terpenoids, and sterols as secondary metabolites families in G. suaveolens extracts. The highest contents of total antioxidants and flavonoids were highlighted in the hydroethanolic extract. However, it’s the G. suaveolens aqueous extract that showed the best free radical DPPH• and ABTS+• scavenging activities (SC50) of 11.06 μg/mL and 15.16 μg/mL respectively. The highest ferric-reducing activity was found in G. suaveolens ethanolic extract with 866.23 μg EGA/mg of dry weight. The hydroethanolic extract has shown a high anti-inflammatory activity through BSA denaturation and erythrocyte membrane haemolysis with inhibitory concentrations 50 (IC50) of 48.63 and 59.22 μg/mL respectively. In contrast, proteinase inhibitory activity revealed a better potential of IC50 (34.19 μg/mL) for the ethanolic extract. In oral acute toxicity, all treated groups revealed neither mortality nor any significant alteration in behaviour and locomotion. The lethal dose 50 (LD50) of G. suaveolens extracts was >5000 mg/kg. These results suggest that G. suaveolens stem-barks extracts may serve as therapeutic sources to prevent inflammation induced by oxidative stress, an important feature of infectious diseases.

浅析氨基酸代谢在生物有机化学与化学生物学教学中的重要性

从氨基酸代谢的基本内容出发,分析并整理了其在生物化学教学中的意义与教学要点,其中富有的各种生物化学过程也充满了趣味性,对于本科生教学是良好的素材。在举例阐述其多样性、复杂性、趣味性与启发性的基础上,讨论生物化学教学中氨基酸代谢相关内容,是一种将前沿科学融入基础生物化学教育的新探索。

以三种非极性氨基酸为例探讨氨基酸合成代谢的化学原理

由于氨基酸代谢的多样性和相对独立性,在基础教学中对相关内容的讨论和推广对培养21世纪新型跨学科人才是极其重要的。本文将以三种基本的非极性天然氨基酸——缬氨酸、异亮氨酸和亮氨酸为例,从氨基酸合成代谢的内容和方式等方面做教学模式的探索,并尝试归纳与总结自然界采取这样代谢路径的原因和逻辑。同时,其中相关的生物化学过程也体现出生命体系所采取的不同寻常的合成路径和反应机制。这对于本科生而言不仅是具有趣味性与启发性的良好的素材,也是了解目前研究热点和积累知识的有效渠道,期望对其后续深入的学习和研究有帮助。

Evaluation of antiviral activities of Houttuynia cordata Thunb.extract,quercetin,quercetrin and cinanserin on murine coronavirus and dengue virus infection

Objective:To evaluate the in vitro activities of the ethyl acetate(EA) fraction of Houttuynia cordata(H.cordata) Thunb.(Saururaceae) and three of its constituent flavonoids(quercetin.quercitrin and rutin) against murine coronavirus and dengue virus(DENV).Methods:The antiviral activities of various concentrations of the EA fraction of H.cordata and flavonoids were assessed using virus neutralization tests against mouse hepatitis virus(MHV) and DENV type 2(DENV-2).Cinanserin hydrochloride was also tested against MHV.The EA fraction of H.cordata was tested for acute oral toxicity in C57BL/6 mice.Results:The EA fraction of H.cordata inhibited viral infectivity up to 6 d.Cinanserin hydrochloride was able to inhibit MHV for only 2 d.The 50%inhibitory concentrations(IC_(50)) of the EA fraction of H.cordata added before the viral adsorption stage were 0.98 μg/mL for MHV and 7.50 μg/mL for DENV-2with absence of cytotoxicity.The mice fed with the EA fraction up to 2 000 mg/kg did not induce any signs of acute toxicity,with normal histological features of major organs.Certain flavonoids exhibited comparatively weaker antiviral activity,notably quercetin which could inhibit both MHV and DENV-2.This was followed by quercitrin which could inhibit DENV-2but not MHV,whereas rutin did not exert any inhibitory effect on either virus.When quercetin was combined with quercitrin,enhancement of anti-DENV-2 activity and reduced cytotoxicity were observed.However,the synergistic efficacy of the flavonoid combination was still less than that of the EA fraction.Conclusions:The compounds in H.cordata contribute to the superior antiviral efficacy of the EA fraction which lacked cytotoxicity in vitro and acute toxicity in vim.H.cordata has much potential for the development of antiviral agents against coronavirus and dengue infections.

Biofilm formation in clinical isolates of nosocomial Acinetobacter baumannii and its relationship with multidrug resistance

Objective: To check biofilm formation by Acinetobacter baumannii(A. baumannii)clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm and multidrug resistance.Methods: This study was performed on clinical samples collected from patients with nosocomial infections in three hospitals of Tehran. Samples were initially screened by culture and biochemical tests for the presence of different species of Acinetobacter. Identifications were further confirmed by PCR assays. Their susceptibilities to 11 antibiotics of different classes were determined by disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The ability to produce biofilm was investigated using methods: culture on Congo red agar, microtiter plate, and test tube method.Results: From the overall clinical samples, 156 specimens were confirmed to contain A. baumannii. The bacteria were highly resistant to most antibiotics except polymyxin B.Of these isolates, 10.26% were able to produce biofilms as shown on Congo red agar.However, the percentage of bacteria with positive biofilm in test tube, standard microtiter plate, and modified microtiter plate assays were 48.72%, 66.66%, and 73.72%, respectively. At least 92% of the biofilm forming isolates were multidrug resistant.Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.

Evaluation of extracts and essential oil from Callistemon viminalis leaves:Antibacterial and antioxidant activities,total phenolic and flavonoid contents

Objective:To investigate antioxidant and antibacterial activities of Callistemon viminalis(C.viminalis)leaves.Methods:The essential oil of C.viminalis leaves obtained by hydrodistillation was analyzed by GC/MS.Different extracts were tested for total phenolic and flavonoid contents and in vitro antioxidant(DPPH assay)and antibacterial(agar disc diffusion and 96-well micro-plates methods)actives.Results:Fourteen components were identified in the essential oil,representing 98.94%of the total oil.The major components were 1,8-cineole(64.53%)andα-pinene(9.69%).Leaf essential oil exhibited the highest antioxidant activity of(88.60±1.51)%comparable to gallic acid,a standard compound[(80.00±2.12)%].Additionally,the biggest zone of inhibitions against the studied bacterial strains was observed by the essential oil when compared to the standard antibiotic(tetracycline).The crude methanol extract and ethyl acetate fraction had a significant antibacterial activity against the tested bacterial strains.Conclusions:It can be suggested that C.viminalis is a great potential source of antibacterial and antioxidant compounds useful for new antimicrobial drugs from the natural basis.The present study revealed that the essential oil as well as the methanol extracts and ethyl acetate fraction of C.viminalis leaves exhibited highly significant antibacterial activity against the tested bacterial strains.

Age structure and static life tables of the endangered Juniperus phoenicea L. in North Sinai Mountains, Egypt:implication for conservation

Studying the population ecology of endangered plants provides important baseline information for its monitoring and conservation.Juniperus phoenicea L.is an endangered species in arid ecosystems in Africa and the Middle East.The static life tables,survival curve and age structure of J.phoenicea populations from two mountains in North Sinai,Egypt(Gabal(G.)El-Halal and G.El-Maghara)were investigated.In each mountain,fifteen plots were selected,and field measurements such as stand density,tree height,and crown diameter were conducted.Moreover,44 trees were cored and crossdated according to standard dendrochronological procedures.The results showed that the tree ages ranged from 50 to 262 years at G.El-Halal and 96 to431 years at G.El-Maghara.Mature J.phoenicea individuals dominated the study area,with only a few individuals being younger than 100 years.Moreover,seedling recruitment was extremely limited.Since the studied J.phoenicea populations showed high mortality rates among both old and young individuals,there is an imminent need for establishing a conservation program to prevent its extinction in the future.Therefore,management and conservation efforts should be made to minimize human disturbance and protect the relic habitats of this endangered species at its southern distribution limits in Africa.