Size and Shape-Dependent Antimicrobial Activities of Silver and Gold Nanoparticles: A Model Study as Potential Fungicides

Plant-based pathogenic microbes hinder the yield and quality of food production. Plant diseases have caused an increase in food costs due to crop destruction. There is a need to develop novel methods that can target and mitigate pathogenic microbes. This study focuses on investigating the effects of luteolin tetraphosphate derived silver nanoparticles (LTP-AgNPs) and gold nanoparticles (LTP-AuNPs) as a therapeutic agent on the growth and expression of plant-based bacteria and fungi. In this study, the silver and gold nanoparticles were synthesized at room temperature using luteolin tetraphosphate (LTP) as the reducing and capping agents. The synthesis of LTP-AgNPs and LTP-AuNP was characterized by Transmission Electron Microscopy (TEM) and size distribution. The TEM images of both LTP-AgNPs and LTP-AuNPs showed different sizes and shapes (spherical, quasi-spherical, and cuboidal). The antimicrobial test was conducted using fungi: Aspergillus nidulans, Trichaptum biforme, Penicillium italicum, Fusarium oxysporum, and Colletotrichum gloeosporioides, while the class of bacteria employed include Pseudomonas aeruginosa, Aeromonas hydrophila, Escherichia coli, and Citrobacter freundii as Gram (-) bacteria, and Listeria monocytogenes and Staphylococcus epidermidis as Gram (+) bacterium. The antifungal study demonstrated the selective size and shape-dependent capabilities in which smaller sized spherical (9 nm) and quasi-spherical (21 nm) AgNPs exhibited 100% inhibition of the tested fungi and bacteria. The LTP-AgNPs exhibited a higher antimicrobial activity than LTP-AuNPs. We have demonstrated that smaller sized AgNPs showed excellent inhibition of A. nidulans growth compared to the larger size nanoparticles. These results suggest that LTP-AuNP and LTP-AgNPs could be used to address the detection and remediation of pathogenic fungi, respectively.

Antimicrobial Activity of a New Class of Phosphorylated and Modified Flavonoids

The surge of resistant food pathogens is a major threat worldwide. Previous research conducted on phytochemicals has shown their antibacterial activity against pathogenic bacteria. The design of antimicrobial agents to curb pathogenic disease remains a challenge demanding critical attention. Flavonoids such as apigenin and quercetin were evaluated against Gram-positive and Gram-negative bacteria. The results indicated that the antibacterial activity of each flavonoid occurred at a different minimum inhibitory concentration. However, the antimicrobial activity results of the modified flavonoids were also reported, and it was observed that the Gram-positive bacteria were more susceptible in comparison to the Gram-negative bacteria. The cell wall structure of the Gram-positive and Gram-negative bacteria could be the main reason for the bacteria susceptibility. Modified flavonoids could be used as a suitable alternative antimicrobial agent for the treatment of infectious diseases. Our results indicated 100% inhibition of Listeria monocytogenes, Pseudomonas aeruginosa, and Aeromonas hydrophila with modified flavonoids.

Selective Sensing and Imaging of Penicillium italicum Spores and Hyphae Using Carbohydrate-Lectin Interactions

The blue-green mold Penicillium italicum is among the most problematic post-harvest plant infections limiting the integrity of citrus and many other crops during storage and transportation, but there is no sensor for its on-site or field detection. We hereby, for the first time, report the development of novel biomolecular sensor for assessing the presence of P. italicum spores and hyphae using carbohydrate-lectin recognitions. Two approaches were developed: (i) lateral tests using standalone poly(amic) acid (PAA) membranes and glass surfaces and (ii) quantitative tests on 96-well polystyrene plates and paper electrodes. In both cases, the surfaces were functionalized with novel derivatized sugar based ligands while staining was performed with gold nanoparticles. Both approaches provided strong signals for 10⁴ spores/mL of P. italicum isolated from experimentally infected lemons as the lowest-reliable concentration. The 96-well plate-based gave the most sensitive detection with a 4 × 10² spores/mL limit of detection, a linear dynamic range between 2.9 × 10³ and 6.02 × 10⁴ spores/mL ( R² = 0.9939) and standard deviation of less than 5% for five replicate measurements. The selectivity of the ligands was tested against Trichaptum biforme, Glomerulla cingulata ( Colletotrichum gloeosporioides), and Aspergillus nidulans fungi species. The highest selectivity was obtained using the sugar-based gold-nanoparticles toward both the spores and the hyphae of P. italicum. The advanced specificity was provided by the utilized sugar ligands employed in the synthesis of gold nanoparticles and was independent from size and shapes of the AuNPs. Accuracy of the sensor response showed dramatic dependence on the sample preparation. In the case of 5-10 min centrifugation at 600 rpm, the spores can be isolated free from hyphae and conidiophore, for which spiked recovery was up to 95% (std ±4). In contrast, for gravity-based precipitation of hyphae, the spiked recovery was 88% (std 11).

Stress-related genes promote Edwardsiella ictaluri pathogenesis

Edwardsiella ictaluri is a Gram-negative facultative anaerobic rod and the causative agent of enteric septicemia of channel catfish (ESC), which is one of the most prevalent diseases of catfish, causing significant economic losses in the catfish industry. E. ictaluri is resistant to complement system and macrophage killing, which results in rapid systemic septicemia. However, mechanisms of E. ictaluri stress responses under conditions of host environment are not studied well. Therefore, in this work, we report E. ictaluri stress responses during hydrogen peroxide, low pH, and catfish serum stresses as well as during catfish invasion. E. ictaluri stress responses were characterized by identifying expression of 13 universal stress protein (USP) genes (usp01-usp13) and seven USP-interacting protein genes (groEL, groES, dnaK, grpE, and clpB, grpE, relA). Data indicated that three usp genes (usp05, usp07, and usp13) were highly expressed in all stress conditions. Similarly, E. ictaluri heat shock proteins groEL, groES, dnaK, grpE, and clpB were highly expressed in oxidative stress. Also, E. ictaluri grpE and relA were highly expressed in catfish spleen and head kidney. These findings contribute to our understanding of stress response mechanisms in E. ictaluri stress response, and stress-related proteins that are essential for E. ictaluri could be potential targets for live attenuated vaccine development against ESC.

An ethnobotanical study in Midyat (Turkey), a city on the silk road where cultures meet

BACKGROUND

Studies of ethnobotanical usages in south-eastern Turkey are rare. To widen this field of knowledge, we conducted an ethnobotanical study in Midyat (Mardin Province), Turkey.

METHODS

The field study was completed during three years (2007-2010). Our aim was to document the ethnobotanical uses of local plants and to make an ethnobotanical inventory of uncommon plants using qualitative interviews.

RESULTS

During field studies, 368 voucher specimens were collected in the investigated area. Ninety-two traditionally used plant species were reported from Midyat and surrounding vicinities in Turkey. Among the 92 taxa (129 usages), 35% were used for medical purposes, 22% for food, 13% for animal fodder, 7% as ornamental plants and dyes, 6% as brooms, 4% for latex and as fragrance, 4% for herbal tea, molasses and wine preparation, 3% for agricultural purposes, and 6% for other purposes. Comparative assessment showed that Teucrium polium (0.51), Matricaria aurea (0.26), Alcea setosa (0.21), and Malva neglecta (0.21) have the highest recorded UVs, and the following taxa had UVs between 0.10-0.20: Anthemis cotula (0.12), Allium cepa (0.13), Alcea striata subsp. striata (0.14), Crupina crupinastrum (0.12), Papaver rhoeas (0.13), Salvia multicaulis (0.14), Thymbra spicata (0.11), and Vicia pannonica subsp. striata (0.15). We reported the ethnobotanical usages of 21 taxa for the first time, in addition to indicating usages previously recorded in the literature. We also recorded four endemic plant usages in the area: Alkanna trichophila var. mardinensis, Centaurea kurdica, Centaurea stapfiana, and Sideritis libanotica subsp. linearis. They have variable leaf and flower morphology that are used traditionally. They are present as well-developed populations and thus their conservation status is not compromised. Additionally, Thymbra sintenisii is a recorded species that is classified as a rare and extensively used species in the region.

CONCLUSIONS

These results contribute to the fundamental knowledge of ethnobotanical usages in Midyat. To date, ethnobotanical studies have not been carried out in this region. This investigation uncovered usages of endemic medicinal plant species and traditional knowledge of Midyat communities living in a mixed culture. The people of Midyat, Batman, and Şırnak are Turkish citizens from various ethnic backgrounds, such as Kurdish, Arabic, and Syriac. We compared our data with results from other studies conducted in Turkey, particularly in south-eastern and eastern regions, as well as with studies from bordering countries, Iraq, Jordan, Syria, and Iran. Nonetheless, more work needs to be conducted to extend the present knowledge for locals to contribute to and evaluate economic potential in the region.

Flavonoid-derived anisotropic silver nanoparticles inhibit growth and change the expression of virulence genes in Escherichia coli SM10

We hereby present a novel greener and ecofriendly synthesis of anisotropic silver nanoparticles (AgNPs) using water soluble quercetin diphosphate (QDP). QDP was employed as a reducing, capping and stabilizing agent at room temperature without any extraneous reagents. The purpose of this study was to determine the effects of modified quercetin pentaphosphate silver nanoparticles (QPP-AgNPs) and quercetin diphosphate derived silver nanoparticles (QDP-AgNPs) on microbial growth and expressions of virulence-related genes in Escherichia coli SM10. The gene expression analysis was carried out for 12 genes which are related to virulence and stress in E. coli SM10, namely: RpoD, RpoS, ibpB, clpB, uspA, fliC, fimH, fimF, kdpE, artJ, hyaA, and gyrA. Results showed that QDP-AgNPs reduced the swarming motility by 98% which correlated with the reduction in the expression of FliC flagellar gene. A simultaneous increase in the expression of the fimbrial genes FimH and FimF that are related to motility was recorded. In contrast, treatment of the microbes with QPP-AgNPs resulted in 90% of the swarming motility at different patterns compared to QDP-AgNPs treatment for the gene expressions of motility elements. The study revealed that QDP-AgNPs up-regulated the stress related RpoD and ibpB expressions, while QPP-AgNPs up-regulated the stress related RpoS and uspA gene expressions. However, both QDP-AgNPs and QPP-AgNPs up-regulated kpdE, artJ and gry at different levels. QDP-AgNPs were also tested for their antibacterial and antifungal activities, which showed μmolar cidal activity. The growth kinetics of both Gram (−) and Gram (+) bacteria were strongly altered by QDP-AgNPs activity. Energy dispersive absorption spectroscopy (EDS) studies revealed that silver ions and/or the nanoparticles themselves transferred into bacterial cells. To the best of our knowledge, this is the first report of studying the genetic and kinetic response of bacteria to modified quercetin phosphate mediated silver nanoparticles and we hereby report that the molecules used to synthesize AgNPs bring about a strong effect on AgNPs manipulatory activity on the tested 12-genes.

We hereby present a novel greener and ecofriendly synthesis of anisotropic silver nanoparticles (AgNPs) using water soluble quercetin diphosphate (QDP). QDP was employed as a reducing, capping and stabilizing agent at room temperature without any extraneous reagents.

Evaluation of the therapeutic use of antibiotics in Aegean Region hospitals of Turkey: a multicentric study

PURPOSE

The antibiotic restriction policy has been validated nationwide since February 2003 by the Ministry of Health because the excessive consumption of antimicrobials causes a high cost. The aim of this study was to evaluate the therapeutic use of antibiotics in Aegean Region hospitals and to assess the impact of this nationwide antibiotic restriction policy. This new policy is based on justification that the infectious disease (ID) physicians should be primarily responsible for the prescription of antimicrobials.

MATERIALS AND METHODS

Eight university and government hospitals were included in the study. The criteria of the Council for Appropriate and Rational Antibiotic Therapy (CARAT) were considered. Both patient-based and antibiotic-based analyses were performed. For the analysis of inappropriate use, logistic regression was modeled.

RESULTS

Therapeutic use was determined in 540 patients by a total of 29 ID physicians.In the study, 30.2% of the patients were given antimicrobials and empirically started antibiotics accounted for 79% cases of therapeutic antibiotic use, and 60% of those were inappropriate (P = 0.001). The appropriate use of ID level antibiotics (P = 0.000) were very compatible with other antimicrobial groups.

CONCLUSION

The study shows that the Turkish government's new intervention policy on antimicrobial prescribing has been effective.

Metabolic syndrome is related to long-term graft function in renal transplant recipients

The metabolic syndrome (MS) is a known cardiovascular risk factor in the general population and a common problem among renal transplant recipients. This study investigated whether MS after renal transplantation affected long-term graft function. We included 112 transplants at our center between 2000 and 2002. We excluded patients with the presence of pretransplant diabetes or nonstable renal function at 1 year after transplantation. We evaluated parameters such as demographic features, medications, smoking history, body mass index, daily proteinuria, blood pressure, number of HLA mismatches, number of acute rejection episodes, delayed graft function, and laboratory parameters. Patients were followed for a mean of 69.86 +/- 21.94 months. The prevalence of MS was determined using the National Cholesterol Education Program-Adult Treatment Panel III criteria. At 1 year after transplant, 28.6% of subjects had MS, whereas only 10.7% had MS before transplantation. Among 27.7% of patients graft failure had occurred during the follow-up; MS was more frequent among these individuals compared with those displaying stable renal function (51.6% vs 19.8%; P = .002). Older donor age, delayed graft function, acute rejection episodes, smoking history, MS, proteinuria, serum creatinine level, and C-reactive protein were associated with graft failure. Upon multivariate Cox regression analysis, patients with MS at 1 year after transplantation showed an increased risk for graft failure (relative risk, 0.22; 95% confidence interval, 0.06-0.75; P = .016). Older donor age and proteinuria level were other independent risk factors for graft failure. The MS was a prominent risk factor for graft failure. Because MS is a cluster of modifiable risk factors, early identification of patients at risk and intervention in due time may improve graft survival.

Is uric acid a predictive factor for graft dysfunction in renal transplant recipients?

Hyperuricemia is a common complication in renal transplant recipients, and uric acid (UA) may play a role in renal dysfunction. The aim of this study was to evaluate the effects of UA on chronic allograft nephropathy (CAN) in renal transplant recipients. The 133 study subjects included 34 women and 99 men of overall mean age of 34.7 +/- 9.9 years. They underwent renal transplantation between 1998 and 2000. Serum UA levels were measured in the first month after transplantation and then at yearly intervals throughout a 3-year follow-up. In the first month after transplantation, 55.3% of recipients had hyperuricemia (UA >7 mg/dL in men; UA >6 mg/dL in women), but, 3 years after transplantation, 84.6% of the subjects had that disorder (P<.001). CAN was diagnosed in 31.5% of the patients at a mean onset of 31.8 +/- 14.3 months after transplantation. Fifty-two percent of these individuals experienced graft failure within 43.3 +/- 20.8 months after transplantation. UA levels were recorded before the development of CAN. There was no association between UA levels and CAN according to a Cox regression analysis (P>.05; relative risk, 1.082; 95% confidence interval [CI] 0.9-1.3). We concluded that the prevalence of hyperuricemia was higher among recipients than in healthy individuals, but that the UA level did not affect the development of CAN during first 3 years after transplantation.

The Association Between Cytomegalovirus Infection and Atherosclerotic Events in Renal Transplant Recipients

Cytomegalovirus (CMV) infection is a risk factor for arteriosclerosis in renal transplant recipients. We sought to investigate the effects of CMV infection on atherosclerotic events (AE) in renal transplant recipients. This retrospective analysis included 200 patients: 52 women and 148 men of overall mean age of 36.18 +/- 10.23 years who were transplanted at our center between 1998 and 2001. We analyzed demographic features, dialysis duration, diabetes, blood pressure level, body mass index (BMI), medications, and lipid parameters. CMV infection was diagnosed in 23.5% of patients in the first 2 years after transplantation; these patients were followed for 4 years. All patients had been assessed for AE, including previous myocardial infarction, angina, revascularization procedures, intermittent claudication, stroke, or transient ischemic attack. AE occurred in 13% during the follow-up period. CMV infection was more frequent among these patients compared to those without AE, namely 42.3% versus 20.6%, respectively. Although the gender, dialysis duration, serum cholesterol level, presence of acute rejection, and BMI were not associated with AE, age, hypertension, and CMV infection did show a relation. A multivariate analysis by logistic regression revealed mean age and CMV infection to be independent risk factors for AE: odds ratio (OR)=5.6, 95% confidence interval (CI)=1.3 to 24.6 (P=0.02) and OR=4, 95% CI = 1.3 to 12.3 (P=.01). This study suggested that the presence of CMV infection may be a triggering factor for AE in renal transplant recipients.

Persistent hypercalcemia is a significant risk factor for graft dysfunction in renal transplantation recipients

Hypercalcemia is a common problem in renal transplant recipients, although in most cases, spontaneous resolution occurs within 1 year after renal transplantation. This condition may persist in some patients producing effects on renal function which are not well understood. In this study, we sought to analyze the effect of persistent hypercalcemia in the posttransplantation period on the function of renal transplants. A total of 121 recipients (31 women, 90 men; mean age, 34.1 +/- 9.9 years) underwent renal transplantation between 1999 and 2002. All patients underwent prospective evaluation of their serum calcium levels at 6-month intervals. A sustained corrected mean serum calcium level higher than 10.2 mg/dL was defined as "persistent hypercalcemia." Patients who had a gradual increase in their serum creatinine levels to >2 mg/dL or a 50% rise above the baseline were considered to display chronic allograft dysfunction (CAD). Among 121 recipients, 52 patients (43%) developed CAD and 37 patients (30.6%) had persistent hypercalcemia. Among the CAD patients, 22 suffered persistent hypercalcemia, while the other 15 patients were without CAD, a difference that was statistically significant (42.3% vs 21.7%, P = .01). The mean calcium levels were lower among patients without than with CAD, a difference that did not reach statistical significance (9.9 +/- 0.4 mg/dL vs 10.1 +/- 0.6 mg/dL, P = .1). In conclusion, persistent hypercalcemia in the posttransplantation period may significantly contribute to the development of chronic allograft nephropathy.

Posttransplant Diabetes Mellitus: Impact of Good Blood Glucose Regulation on Renal Transplant Recipient Outcome

Posttransplant diabetes mellitus (PTDM) is a frequent complication among renal transplant recipients. This study sought to compare clinical outcomes of patients with PTDM who had strict glucose control with nondiabetic patients and to identify risk factors for atherosclerotic disease in both groups. We retrospectively examined 204 renal allograft recipients transplanted at our center between 1996 and 2002. Demographic features, dialysis and posttransplantation duration, smoking, body mass index, medications, comorbid diseases, number of HLA mismatches, and laboratory parameters including serum levels of creatinine, albumin, calcium, phosphorus, C-reactive protein, lipid parameters, and parathyroid hormone were analyzed as possible risk factors for atherosclerotic disease. Patients were followed for a mean of 59.7 +/- 23.6 months. PTDM was diagnosed according to the American Diabetic Association criteria or the need for an insulin/oral hypoglycemic agent. Twenty-six patients developed PTDM, and these patients had very good diabetes control. One patient with poorly regulated PTDM was excluded. Adverse events which were documented in 24 patients were more frequent among patients with PTDM. Mean age was found to be an independent risk factor for atherosclerotic disease, whereas PTDM was not. There were no differences regarding other atherosclerosis-related or other risk factors (including serum C-reactive protein levels and lipid profiles) between the groups. Nondiabetic subjects tended to have longer graft survival than patients with PTDM, but this finding was not statistically significant. PTDM is an important risk factor for developing atherosclerotic disease. Good control of blood glucose levels can decrease the high morbidity rates and negative influence of PTDM on patient and graft survival rates in this population.

Effects of smoking and blood eosinophil count on the development of arteriovenous fistulae thrombosis in hemodialysis patients

Arteriovenous fistulae (AVF) failure is the most common cause of morbidity and hospitalization in hemodialysis (HD) patients. The purpose of this study was to determine the effects of smoking and blood eosinophil count on the development of AVF thrombosis in HD patients. This cross-sectional study included 141 patients (M/F 80/61; age 43.4 +/- 11.6 years, HD duration 7.7 +/- 4.4 years). The following were analyzed as possible risk factors for AVF failure for all patients: demographic features, dialysis time, smoking, medications, body mass index, comorbid diseases, and various laboratory parameters (whole blood count and serum levels of albumin, calcium, phosphorus, uric acid, C-reactive protein, ferritin, and parathyroid hormone). AVF thrombosis was detected in 60 patients; in contrast, 81 patients had no thrombosis. Distributions of age, gender, and HD duration were similar between both groups. Univariate analysis showed that snuffbox AVF location (P < .0001), higher blood eosinophil count (P < .0001), smoking (P < .01), and higher hematocrit level (P < .05) were all associated with AVF thrombosis. According to multivariate analysis by logistic regression models, eosinophil count (RR = 1.005, P < .05) and snuffbox location (RR = 5.970, P < .05) were predictors of AVF thrombosis. When AVF location was excluded from the analysis, smoking (RR = 4.140, P < .01) and high blood eosinophil count (RR = 1.006, P < .005) were independent risk factors for thrombosis. Our study indicates that smoking and high blood eosinophil count may contribute to the development of AVF thrombosis.