Physiological and biochemical responses of selected weed and crop species to the plant-based bioherbicide WeedLock.

WeedLock is a broad-spectrum plant-based bioherbicide that is currently on the market as a ready-to-use formulation. In this study, we investigated the physiological and biochemical effects of WeedLock (672.75 L ha-1) on Ageratum conyzoides L., Eleusine indica (L.) Gaertn, Zea mays L., and Amaranthus gangeticus L. at four different time points. WeedLock caused significant reductions in chlorophyll pigment content and disrupted photosynthetic processes in all test plants. The greatest inhibition in photosynthesis was recorded in A. conyzoides at 24 h post-treatment with a 74.88% inhibition. Plants treated with WeedLock showed increased malondialdehyde (MDA) and proline production, which is indicative of phytotoxic stress. Remarkably, MDA contents of all treated plants increased by more than 100% in comparison to untreated. The activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) was elevated following treatment with WeedLock. Significant increases were observed in the SOD activity of A. conyzoides ranging from 69.66 to 118.24% from 6 to 72 h post-treatment. Our findings confirm that WeedLock disrupts the normal physiological and biochemical processes in plants following exposure and that its mode of action is associated with ROS (reactive oxygen species) production, similar to that of PPO (protoporphyrinogen oxidase) inhibitors, although specific site-of-action of this novel bioherbicide warrants further investigation.

Bioherbicides: An Eco-Friendly Tool for Sustainable Weed Management.

Weed management is an arduous undertaking in crop production. Integrated weed management, inclusive of the application of bioherbicides, is an emerging weed control strategy toward sustainable agriculture. In general, bioherbicides are derived either from plants containing phytotoxic allelochemicals or certain disease-carrying microbes that can suppress weed populations. While bioherbicides have exhibited great promise in deterring weed seed germination and growth, only a few in vitro studies have been conducted on the physiological responses they evoke in weeds. This review discusses bioherbicide products that are currently available on the market, bioherbicide impact on weed physiology, and potential factors influencing bioherbicide efficacy. A new promising bioherbicide product is introduced at the end of this paper. When absorbed, phytotoxic plant extracts or metabolites disrupt cell membrane integrity and important biochemical processes in weeds. The phytotoxic impact on weed growth is reflected in low levels of root cell division, nutrient absorption, and growth hormone and pigment synthesis, as well as in the development of reactive oxygen species (ROS), stress-related hormones, and abnormal antioxidant activity. The inconsistency of bioherbicide efficacy is a primary factor restricting their widespread use, which is influenced by factors such as bioactive compound content, weed control spectrum, formulation, and application method.

Q fever: a neglected zoonosis in Saudi Arabia.

BACKGROUND AND OBJECTIVES: Infection due to Coxiella burnetii (C burnetii), the causative agent of Q fever is rarely sought for in clinical practice. This study was performed to detect C burnetii infection in patients with pyrexia of undetermined cause (PUC). DESIGN AND SETTINGS: This is a prospective study conducted at King Khalid University Hospital, Riyadh be.tween March 2011 and January 2013. PATIENTS AND METHODS: A total of 3 mL venous blood was collected from 51 patients with PUC at King Khalid University Hospital, Riyadh. This group of patients included 30 males and 21 females (mean age 33.9 [21.3] years) with the history of febrile illness ranging between 4 and 8 weeks. A control group of 50 healthy individuals comprising 39 males and 11 females (mean age 27 [9] years) was also included in the study. Detection of phase II C burnetii-specific IgG antibodies was performed by immunofluorescence assay, and a titer of > 1:64 was considered positive. RESULTS: Phase II C burnetii-specific IgG antibodies were detected in 18 (35.2%) patients out of the total 51 tested. Two (4%) individuals out of 50 in the control group tested positive for anti-C burnetii IgG antibodies. The proportion of positive results among the patients was significantly higher than the controls (P < .0002, 95% CI, 15.09-46.25). The antibody titer range was between 1:128 and 1:1024 where 6 patients had titers of 1:256, 5 had 1:512, 4 had 1024, and 3 had 1:128. CONCLUSION: The evidence of C burnetii infection in a sizable number of patients emphasizes the need for inclusion of serologic investigations for Q fever in patients with PUC.

Modifications influencing Widal test reactivity in a novel microplate assay.

Reliability of the Widal tube agglutination test has been the subject of many controversies over the years. This study was performed to assess the effect of certain modifications on the performance of Widal test in a novel microplate assay. Sera from 37 patients (21 males; 16 females) (mean age 28 +/- 7 years) were tested in the Immunology Unit at King Khalid University Hospital, Riyadh. Among them were 26 patients with suspected typhoid fever and 11 had bacteriologically confirmed diagnosis of Salmonella infection. The modifications included either the use of 0.5% bovine serum albumin (BSA), absorption of sera with sheep red blood cells (SRBC) or heat inactivation of sera. Compared with Widal tube agglutination test, microplate assay with SRBC absorption of the sera from patients with suspected typhoid fever was not only associated with enhancement of detection titers for both H (p < or = 0.001) and O (p < or = 0.005) Salmonella agglutinins but also the percentage of reactivity. The presence of BSA augmented detection titers for Salmonella H agglutinins (p < or = 0.02) only. Heat inactivation of sera however was found to be associated with reduction in the detectable titers for both H (p < or = 0.03) and O (p < or = 0.01) agglutinins. Increased titers of Salmonella agglutinins were also evident in 11 patients with confirmed diagnosis of Salmonella infection. The novel microplate agglutination assay using the SRBC absorption was associated with enhancement in Widal test reactivity and appears to be a useful alternative for the diagnosis of Salmonella infection.

Pattern of patch test reactivity among patients with clinical diagnosis of contact dermatitis: a hospital-based study.

BACKGROUND AND OBJECTIVES: Contact allergy is associated with a significant morbidity all over the world. This study was performed to investigate the pattern of sensitization by contact allergens in the local population. DESIGN AND SETTING: Retrospective study to investigate patch test reactivity among patients with clinical diagnosis of contact dermatitis who were referred to the allergy clinic at the King Khalid University Hospital, Riyadh, between April 2008 and March 2010. PATIENTS AND METHODS: Of the 196 patients referred to the allergy clinic over the 2-year period, 91 (46.4%) patients reacted to one or more patch test allergens, and these patients were included in this study. The study group included 82 (91.1%) of Saudi nationality and 9 (8.9%) patients of other nationalities. The patch test was performed using the T.R.U.E TEST, containing 24 allergens/allergen mixes. RESULTS: Of the 91 cases who reacted positively to one or more allergens, 67 (73.6%) were females with a mean age of 37 (8.3 years) and 24 (26.4%) were males with a mean age of 34 (11.6 years). Thirty-three (36.2%) patients reacted to nickel sulfate, 14 (15.3%) to p-phenylenediamine, 13 (14.2%) to p-tert-butylphenol-formaldehyde resin, 13 (14.2%) to thimerosal, and 9 (9.8%) to colophony. Reactivity against the rest of the allergens was not remarkable. A significantly higher percentage of females reacted to nickel sulfate (84.8% vs 15.2% in males;P=.0001), p-tert-butylphenol-formaldehyde resin (92.3% vs 7.7%; P=.0001), and thimerosal (76.9% vs 23.1%;P=.03). CONCLUSIONS: Patch test reactivity to nickel sulfate was high. The pattern of contact allergy observed in this study indicates the need for large-scale investigations to identify local allergens responsible for contact allergy and for formulation of policies directed towards avoidance of exposure.

Epidemiological, clinical, and biochemical characteristics of Saudi patients with nonalcoholic fatty liver disease: a hospital-based study.

BACKGROUND: The estimated prevalence of nonalcoholic fatty liver disease (NAFLD) in Saudi Arabia is 7% to 10%. Despite the high prevalence of risk factors including diabetes, obesity, and hyperlipidemia, no recent epidemiological studies have measured the disease burden. We aimed to determine the characteristics of Saudi NAFLD patients attending a university hospital, and study factors affecting alanine aminotransferase (ALT) levels. DESIGN AND SETTING: A prospective study among patients referred for ultrasonography in King Khalid University Hospital in Riyadh, Saudi Arabia from February to May 2009. PATIENTS AND METHODS: NAFLD was defined as an appearance of fatty liver on routine abdominal ultrasound in the absence of coexisting liver disease and alcohol consumption. Patients were classified into normal and high ALT (ALT >60 U/L) level groups for analysis. RESULTS: The prevalence of NAFLD was 16.6% (218/1312). Patients with normal ALT had the mean (SD) age of 45.9 (10.6) years and the mean body mass index of 34.5 (7.9) kg/m2. Forty percent of the 151 patients with normal ALT had diabetes, 66.2% were obese, and 29.1% had hypertension. Forty-three patients (23%) had high ALT levels. These patients had significantly lower age (P=.003) and fasting blood sugar (P=.03) than the normal ALT group. Non-diabetic patients (odds ratio 0.30, 95% CI 0.1-0.8), men (female OR 0.23, 95% CI 0.1-0.5), lower cholesterol (P=.001), high-density lipoprotein (P=.006), and low-density lipoprotein (P=.008) levels were more likely to be observed among patients with high ALT levels. In a multivariate analysis, younger age (OR 0.96, 95% CI 0.93-0.99), being male (OR 0.23, 95% CI 0.09-0.57), and a lower cholesterol level (OR 0.55, 95% CI 0.37-0.82) were significant predictors of high ALT levels. CONCLUSION: Based on the high prevalence of obesity and diabetes, the prevalence of NAFLD will continue to be high, unless awareness is inculcated among the local population.

Detection of Salmonella typhi agglutinins in sera of patients with other febrile illnesses and healthy individuals.

BACKGROUND AND PURPOSE: Widal test is frequently applied for the detection of Salmonella agglutinins to diagnose Salmonella enterica serotype Typhi infection. There are however a number of controversies challenging the diagnostic utility of this test. This study was performed to determine the prevalence of Salmonella agglutinins in patients with other febrile illnesses and healthy blood donors. MATERIALS AND METHODS: Sera from 50 healthy blood donors were compared for the presence of Salmonella agglutinins in various groups of patients with other febrile illnesses using Widal test in the division of Serology and Immunology at King Khalid University Hospital, Riyadh. The patient groups of other febrile illnesses included infections with Beta-hemolytic streptococcus (n = 50), Brucella (n = 46), Helicobacter pylori (n = 24), Treponema pallidum (n = 30), Toxoplasma (n = 44), and other parasites (n = 20). RESULTS: Majority of the patients and normal individuals were tested positive for Widal test at dilution of less than 1 : 40 both for the O (62.5%) and H (64.6%) antigen. A decreasing trend in Widal reactivity was observed with increasing dilutions of the serum samples. At 1 : 160 titer, which is generally considered as a cut off point for positive Widal test, 6.4 and 11% individuals had positive Widal test for O and H Salmonella antigens, respectively. CONCLUSION: Detection of a significant number of positive Widal tests in conditions where it is expected to be nonreactive appears to be a serious problem in making a correct diagnosis of typhoid fever, thus challenging the diagnostic utility of the Widal test.