Prevalence of Helicobacter pylori infection among healthcare workers in Aswan University Hospital.

BACKGROUND AND STUDY AIM: Helicobacter pylori (H. pylori) is the major pathogen causing upper alimentary tract diseases and has various routes of transmission. It is considered a public health concern owing to its high prevalence. Therefore, proper investigations should be conducted and early treatment modalities developed to avoid its hazardous complications. This study aimed to evaluate the prevalence of H. pylori infection among healthcare workers (HCWs) in Aswan University Hospital, Aswan Governorate, Egypt. PATIENTS AND METHODS: This cross-sectional study was conducted between June and November 2021 and included 200 HCWs who completed a predesigned questionnaire. A serological test was employed to screen for H. pylori infection, followed by a stool antigen test for those with positive serology for direction to the associated clinic for therapy. RESULTS: Of the 200 HCWs included in the study, 86 (43 %) were men and 114 (57 %) were women. Their age was 18-58 years. The participants consisted of doctors (31.5 %), nurses (53 %), and workers (15.5 %). The overall prevalence was (58.5 %) of the study participants were seropositive for H. pylori with higher prevalence in women (56.4 %) with no statistical difference (p = 0.841).The age of the participants and work duration exhibited a weak positive correlation with positivity for H. pylori infection (p = 0.033 and p = 0.049, respectively). CONCLUSION: HCWs are considered to be at a high risk of developing H. pylori infection. Age and work duration were found to contribute to the acquisition of infection. Preventive hospital measures, such as universal precaution, frequent handwashing, and wearing of gloves and a mask/face guard, should be taken to prevent occupational infection.

A Zebra Diagnosis: A Case of Spontaneous Hematomyelia Associated With COVID-19.

Spontaneous non-traumatic spinal hematomyelia, characterized by intramedullary spinal hematoma, is a rare neurological emergency. Bleeding arteriovenous malformation, coagulopathies, and neoplasms are reported causes of this rare diagnosis. The authors present a case of a previously healthy man who presented with acute paraplegia and was found to have a spontaneous hematomyelia in association with covid infection. He underwent laminectomy and hematoma evacuation but did not recover any neurological function.

Regulatory B cells (Bregs) in Helicobacter pylori chronic infection.

BACKGROUND: Helicobacter pylori (H. pylori) infection is linked with a wide variety of diseases and was reported in more than half of the world's population. Chronic H. pylori infection and its final clinical outcome depend mainly on the bacterial virulence factors and its ability to manipulate and adapt to human immune responses. Bregs blood levels have been correlated with increased bacterial load and infection chronicity, especially Gram-negative bacterial infection. This study aimed to identify prevalence and virulence factors of chronic H. pylori infection among symptomatic Egyptian patients and to examine its possible correlation to levels of regulatory B cells (Bregs) in blood. MATERIALS AND METHODS: Gastric biopsies and blood samples from each of 113 adult patients, who underwent upper endoscopy, were examined for the detection of H. pylori by culture and PCR methods. Conventional PCR was used to determine various virulent genes prevalence and association to clinical outcome. Flow cytometry was used to evaluate Bregs levels. RESULTS: Helicobacter pylori prevalence was 49.1% (55/112). Regarding virulence genes incidence, flaA gene was detected in 73% (40/55), vir B11 in 56.4% (31/55), hopZ1 in 34.5% (19/55), hopZ2 in 89% (49/55), babA2 in 52.7% (29/55), dupA jhp917 in 61.8% (34/55), vacA m1/m2 in 70.9% (39/55), and vacA s1/s2 in 69% (38/55) strains. Bregs levels were significantly lower in H. pylori-infected patients (p = 0.013), while total leukocyte count (TLC) showed no significant differences. CONCLUSION: Helicobacter pylori infection prevalence was almost 49%, and the infection was found to be related to inflammatory conditions as gastritis and ulcers rather than malignant transformations. Also, we found that CD24+ CD38+ B cells were downregulated in H. pylori-infected patients.

Detection of hepatitis C virus (HCV) RNA in the peripheral blood mononuclear cells of HCV-infected patients following sustained virologic response.

It is unclear whether direct-acting antiviral drugs (DAAs) result in the complete eradication of HCV infection or whether some quantities of the virus may persist after achieving a sustained virologic response (SVR). Aim The aim of this work was to study the possibility of the persistence of HCV RNA in peripheral blood mononuclear cells (PBMCs) after achieving SVR following DAA treatment. This study included 100 patients infected with HCV genotype 4, who were candidates for receiving DAAs and who achieved SVR during follow-up, as determined at 12 and/or 24 weeks following the end of treatment. All patients were subjected to demographic, biochemical and hematological assessments. Detection of HCV RNA in the serum and PBMCs and determination of the HCV genotype were performed with real-time PCR. We detected HCV RNA in the PBMCs of 20 out of 100 (20%) patients infected with HCV genotype 4, who achieved SVR. However, the persistent viral load in the PBMCs was very low (range: 400-900 U/mL; mean ± SD: 645.45 ± 153 U/mL). Multiple logistic regression analysis showed that only the higher posttreatment levels of aspartate transaminase (AST) were significantly predictive of HCV RNA persistence in the PBMCs (OR: 1.29; 95% CI: 1.08-1.55). Additionally, according to the Cox proportional hazard model, liver cirrhosis was the only significant risk factor for the persistence of HCV infection in PBMCs (HR: 5.8; 95% CI: 1.3-26.1; P < 0.02). Our results indicated the persistence of HCV RNA in some HCV patients who achieved SVR after treatment with DAAs.

Impact of bone marrow mesenchymal stem cells on the submandibular gland structure of adult male albino rats exposed to cadmium chloride toxicity.

OBJECTIVE: This study was carried out in submandibular salivary glands of rats to demonstrate the changes induced by cadmium intoxication and the possible prophylactic and therapeutic effects of bone marrow mesenchymal stem cells (BMSCs). DESIGN: Sixty-five rats were divided into five groups. Rats in Group I were controls while those of Group II received daily dose of 10 mg/kg cadmium for 24 days. Rats in Group III received single prophylactic dose of 1 × 106 BMSCs one week before cadmium administration. Rats of Group IV were concomitantly administered cadmium and BMSCs, while those of Group V received cadmium for 24 days and were then treated with single dose of 1 × 106 BMSCs. Rats of Groups I, II, III, and IV were euthanized at the end of the experiment while those of Group V were euthanized one week later. Salivary gland specimens were processed and stained with H&E and inducible nitric oxide synthase; other specimens were used to demonstrate metallothionein gene expression using RT-PCR, malondialdehyde and catalase enzymes were detected by ELISA. RESULTS: Groups III and IV had nearly comparable findings to Group I regarding histological pattern with normal gland features. Group III recorded a lower fold of change for metallothionein gene (1.14 ± 0.20), a lower malondialdehyde enzyme (21.67 ± 1.63 nmol/mg), and a higher catalase enzyme (66.33 ± 2.16 mmol/mg). Regarding all variables, significant differences were found between the different groups (P < 0.001). CONCLUSION: BMSCs have prophylactic and therapeutic effects against cadmium-induced cytotoxicity in rat salivary glands.

Predictive value of the glycated albumin versus glycosylated hemoglobin in follow-up of glucose homeostasis in hemodialysis-maintained type-2 diabetic patients.

Objectives. Markers for glucose control in hemodialysis patients (HDP) are debated. Glycosylated hemoglobin (HbA1c%) relies on the stable red blood cell survival. Albumin turnover is faster than hemoglobin. Glycated albumin (GA%) may be used as an index of short-term glycemic control. The predictive value of GA% versus HbA1c% in monitoring the glucose homeostasis in type-2 diabetic HDP is studied. Methods. Forty type-2 diabetic HDP and 20 healthy non diabetic subjects matched age and sex as a control group were included. Calculation of body mass index and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and urea reduction ratio were done. Glycosylated hemoglobin, glycated albumin, fasting blood glucose, insulin, total lipid, kidney and liver functions tests, hepatitis markers, electrolytes, complete blood count, and international normalized ratio were performed. Patients were followed up after 6 months. Results. The study showed that GA% is more sensitive than HbA1c%, but less specific in the follow-up of the glucose homeostasis in type-2 diabetic HDP. Diagnostic accuracy is higher in HbA1c% than in GA%. HOMA-IR is superior regarding the sensitivity and the diagnostic accuracy. Conclusion. The present data show that GA% is more sensitive than HbA1c% and has more diagnostic accuracy in the follow-up of the glucose homeostasis in type-2 diabetic HDP.

Clinical role of MiRNA 29a and MiRNA 335 on breast cancer management: their relevance to MMP2 protein level.

BACKGROUND: Circulating miRNAs are novel biomarkers, authors aimed to investigate the expression level of miR-29a and miR-335 and their relevance to CEA, CA15.3, and matrix metalloproteinase-2 (MMP2). MATERIALS AND METHODS: Breast cancer (BC) patients (n = 44), benign breast lesion patients (n = 25), and healthy individuals (n = 19) were enrolled for detection of miRNA expression levels, MMP2 and biochemical markers using quantitative polymerase chain reaction (PCR) and ELISA, respectively. RESULTS: Expression of miR-29a and miR-335 were significantly decreased in breast patients as compared to healthy individuals, while biochemical markers were high in BC patients as compared to the other two groups. The diagnostic efficacy for miR-29a, miR-335, and MMP2 were superior to both CEA and CA 15.3 for early detection of BC patients. CONCLUSIONS: Detection of the miR-29a and miR335 expression levels in serum samples are significant promising biomarkers for BC diagnosis.

Tumor characteristics of hepatocellular carcinoma after direct-acting antiviral treatment for hepatitis C: Comparative analysis with antiviral therapy-naive patients.

BACKGROUND: Insufficient and contradictory data are available about the relation between direct-acting antivirals (DAAs) and hepatocellular carcinoma (HCC) development in patients with hepatitis C virus (HCV). AIM: To analyze differences in basic clinical, radiological, and laboratory characteristics in addition to tumor behavior upon HCC diagnosis between patients with and without a previous history of DAAs exposure. METHODS: This multicenter case-control study included 497 patients with chronic HCV-related HCC, allocated into one of two groups according to their history of antiviral treatment for their HCV. RESULTS: Group I included 151 HCC patients with a history of DAAs, while 346 patients who had never been treated with DAAs were assigned to group II. A significant difference was observed between both groups regarding basic assessment scores (Child, MELD, and BCLC), which tended to have more advanced liver disease and HCC stage upon diagnosis in group I. However, serum albumin was significantly affected, and serum α-fetoprotein was significantly higher in group II (P < 0.001). In addition, group I showed significant HCC multicentricity than group II, while the incidence of portal vein thrombosis was significantly higher in group I (P < 0.001). CONCLUSION: The basic clinical scores and laboratory characteristics of HCC patients are advanced in patients who are naïve to DAAs treatment; however, HCC behavior is more aggressive in DAA-treated patients.

Gastric antral vascular ectasia in hepatitis C virus related liver cirrhosis: Fetching for predictors.

BACKGROUND AND AIM: Gastric antral vascular ectasia (GAVE) is observed in patients with liver cirrhosis and portal hypertension. The exact pathophysiologic mechanism that underlies this condition is unknown. In our study, we estimate the prevalence of GAVE in hepatitis C virus (HCV) cirrhosis and attempted to determine if any of the hepatocellular manifestations, liver functions, serum gastrin, abdominal ultrasound and endoscopic picture have a relation to, or could predict, the occurrence of GAVE in cirrhotic patients. METHODS: This study includes 500 HCV-related liver cirrhosis patients. According to endoscopic assessment, we detected 30 patients with GAVE (Group 2). From the 470 patients without GAVE, we randomly selected 120 patients (Group 1), to avoid statistical bias, for comparison with Group 2. Comparison included clinical manifestations, laboratory findings, serum gastrin, ultrasound findings, and endoscopic findings (esophageal and/or gastric varices and gastropathy). RESULTS: The percentage of GAVE in HCV-related liver cirrhosis is 0.06%. We can predict GAVE by platelets, palmer erythema, diabetes mellitus (DM), marked ascites > with area under the curve of 0.67, 75.5, 0.62, and 0.40%, and accuracy of 82.5, 72, 70.7, and 79.3%, respectively. There was no correlation found between occurrence of GAVE and endoscopic findings. Also, there was no correlation found between occurrence of GAVE and serum gastrin levels, which reflect another pathophysiology, and we found no statistically significant correlation with GAVE. CONCLUSIONS: Palmer erythema, low platelets, DM, and ascites might help in the prediction of GAVE. GAVE is not linked to the presence, type or grade of varices, and gastropathy.

Modified Bilateral Perialar Crescent Flap for Reconstruction of Combined Upper Lip and Premaxillary Defect.

Many reconstruction methods are performed for combined defects of upper lip and premaxilla in oral cancer patients, which are complicated and multiple staged procedures, compromising the functional or structural unit. In this case report, we present a modification of the bilateral perialar crescent flap for reconstructing the combined defect of upper lip and premaxilla in a single stage. A patient diagnosed with well-differentiated squamous cell carcinoma of premaxilla and upper lip, involving a surgical defect of more than one-third but less than two-thirds of the lip underwent two cycles of neoadjuvant chemotherapy. Later wide local excision of the lesion and simultaneous reconstruction with a modified perialar crescent flap was performed in a single stage. Patient recovered uneventfully and tolerated the procedure well, without any complications. The patient was found to be satisfied with the functional and esthetic result. The reduced upper lip support which was a result of the bony defect of the premaxilla, was corrected with a dental prosthesis. This modification is a useful reconstruction tool for oral cancer patients with combined defects of upper lip and premaxilla.

Metastatic Tumour to the Mandible - A Diagnostic and Management Dilemma.

Metastatic tumours of the jaw are overlooked due to their relatively rare incidence. However, they are often the first indicators of an unknown primary malignant lesion. In this case report, we present a 68-year-old male patient with a suspected intraosseous malignancy of the mandible who was treated by a right segmental mandibulectomy. The final histopathology report was indicative of a secondary metastatic tumour. Positron emission tomography scan revealed a suspicious lesion in the right lung, which was identified as the primary tumour by biopsy using the Tru-Cut® biopsy device (MeritMedical, Jordan UT). The metastatic lesion to the oral soft tissues was easily recognized, in contrast to the jawbone metastasis. Differentiating between primary intraosseous and metastatic mandibular tumours relies on the histopathologist and the surgeon working in tandem to arrive at an early conclusive diagnosis. Knowledge of metastatic tumours to the facial bones is indispensable to a surgeon as it can often be the first indication of an unknown primary malignancy. Identification of early signs, appropriate and timely investigative procedures, coordination between pathologist and surgeon, and choosing the correct treatment modality can help prolong and improve the quality of life of the patient.

Event-related evoked potential versus clinical tests in assessment of subclinical cognitive impairment in chronic hepatitis C virus.

CONTEXT: Chronic infection by hepatitis C virus causes impairment in neurocognitive function in up to 50% of patients which may not be detected by clinical tests. AIM: Early detection of neurocognitive impairment in chronic hepatitis C patients and investigating the cognitive function in HCV patient by p300 and clinical test. MATERIALS AND METHODS: The study included 60 patients with chronic hepatitis C and 30 healthy controls. Participants were subjected to a biochemical, hematological assessment, mini-mental state examination, Montreal Cognitive Assessment, P300, polymerase chain reaction (PCR), and fibroscan made for hepatitis C patients. RESULTS: The digit span, attention, concentration, and memory were significantly lower in patients than controls. The delayed P300 peak latency and the reduction of its amplitude were significantly evident in patients with liver fibrosis than the controls and patients without fibrosis. These abnormalities were significantly higher with increasing the grade of fibrosis. All patients with cognitive impairment (reduced mini-mental state score) had abnormal P300-evoked responses. P300 could detect neurocognitive impairment in some patients with normal neurocognitive functions by clinical test. P300 had sensitivity (100%), specificity (59.26), positive predictive value (75%), negative predictive value (100%), and accuracy (81.67) in the detection of neurocognitive impairment in HCV patient. CONCLUSION: Patients with chronic hepatitis C infection had significant impairment in their cognitive functions. This impairment increases with the increase in grade of hepatic fibrosis. P300 can detect minimal and subclinical impairment of cognitive function at early stages of chronic hepatitis with accuracy (81.67). TRIAL REGISTRATION: PACTR on 19 march 2018 retrospectively. Identification number for the registry is PACTR201804003215168.

Rice Bran Oil Improves Insulin Resistance by Affecting the Expression of Antioxidants and Lipid-Regulatory Genes.

The present study investigated the molecular effects of rice bran oil (RBO) on lipid-regulatory genes (sterol regulatory element binding protein-1 [Srebf1] and peroxisome proliferator-activated receptors-α [Ppara]) and the expression of catalase (CAT) and superoxide dismutase (SOD1) genes in insulin-resistant rats. Rats were divided into five groups: animals that received standard diet (control); rats fed standard diet containing RBO as the sole source of fat (RBO); a high-fructose diet (HFD) group, which was further divided into two subgroups: rats fed HFD either for only 1 month (HFD1) or for 2 months (HFD2) and rats fed HFD containing RBO for 1 month; while rats in the last group fed HFD for 30 days then treated with RBO for another 30 days. The HFD induced a state of insulin resistance (IR) as indicated by the hyperinsulinemia and elevated homeostasis model assessment insulin resistance index. Hepatic lipid levels and radical scavenging enzymes were altered by the HFD. Lipid-regulatory genes, Srebf1 and Ppara, were upregulated while Sod1 and Cat were downregulated in insulin-resistant rats. Addition of RBO to the two diet regimens alleviated the disorders of IR to some extent. RBO reduced the hepatic levels of triacylglycerol, malondialdehyde, SREBP, and PPAR-α mRNA. Hepatic SOD and CAT were elevated at gene and protein levels. The HFD induces de novo lipogenesis by upregulating the lipid-regulatory genes resulting in increased serum and hepatic triacylglycerol. Moreover, IR induced by the HFD caused a state of oxidative stress. Supplementation of RBO to fructose-fed rats not only improves insulin resistance but also downregulates lipogenic genes and improves the unbalanced oxidative status.

Role of biomarkers in the prediction and diagnosis of hepatocellular carcinoma.

The prevalence of hepatocellular carcinoma (HCC) has progressively increased in recent years and is now the fifth and the second most common cancer in the World and in Egypt, respectively. Much work has focused in the development of assays for detecting hepatic carcinogensis before the observance of hepatic focal lesions. Particular attention has been directed towards HCC-specific biomarkers for use in the early diagnosis of HCC and in the confirmation of radiological studies. Although a number of biomarkers have been identified, none have been considered reliable indicators of early HCC lesions. This review presents a few of the most relevant HCC biomarkers and suggests improvements to the accuracy of diagnostic assays through their combined use. Furthermore, we present an algorithm for the biomarker-based diagnosis of HCC and highlight its important role in the early prediction of HCC.

A double-blind randomized clinical trial on the efficacy of cortical direct current stimulation for the treatment of Alzheimer's disease.

BACKGROUND: The purpose of this study was to investigate the long-term efficacy of transcranial direct current stimulation (tDCS) in the neurorehabilitation of Alzheimer's disease (AD). METHODS: Thirty-four AD patients were randomly assigned to three groups: anodal, cathodal, and sham tDCS. Stimulation was applied over the left dorsolateral prefrontal cortex for 25 min at 2 mA, daily for 10 days. Each patient was submitted to the following psychometric assessments: mini-mental state examination (MMSE) and Wechsler adult intelligence scale-third edition at base line, at the end of the 10th sessions and then at 1 and 2 months after the end of the sessions. Motor cortical excitability and the P300 event-related potential were assessed at baseline and after the last tDCS session. RESULTS: Significant treatment group × time interactions were observed for the MMSE and performance IQ of the WAIS. Post hoc comparisons showed that both anodal and cathodal tDCS (ctDCS) improved MMSE in contrast to sham tDCS. Whereas, this was only true for ctDCS in the performance IQ. Remarkably, tDCS also reduced the P300 latency, but had no effect on motor cortex excitability. CONCLUSION: Our findings reveal that repeated sessions of tDCS could not only improve cognitive function but also reduce the P300 latency, which is known to be pathologically increased in AD.

Olfactory learning of plant genotypes by a polyphagous insect predator.

Olfactory learning may allow insects to forage optimally by more efficiently finding and using favourable food sources. Although olfactory learning has been shown in bees, insect herbivores and parasitoids, there are fewer examples from polyphagous predators. In this study, olfactory learning by a predatory coccinellid beetle is reported for the first time. In laboratory trials, adults of the aphidophagous ladybird Coccinella septempunctata did not prefer the odour of one aphid-infested barley cultivar over another. However, after feeding on aphids for 24 h on a cultivar, they preferred the odour of that particular cultivar. The mechanism appeared to be associative learning rather than sensitisation. Although inexperienced ladybirds preferred the odour of an aphid-infested barley cultivar over uninfested plants of the same cultivar, after feeding experience on a different cultivar this preference disappeared. This may indicate the acquisition and replacement of olfactory templates. The odour blends of the different aphid-infested barley cultivars varied qualitatively and quantitatively, providing a potential basis for olfactory discrimination by the ladybird. The results show that predatory coccinellids can learn to associate the odour of aphid-infested plants with the presence of prey, and that this olfactory learning ability is sensitive enough to discriminate variability between different genotypes of the same plant.

Effect of within-species plant genotype mixing on habitat preference of a polyphagous insect predator.

The effects of within-species plant genotype mixing on the habitat preference of a polyphagous ladybird were studied. Plant species diversity is often claimed to positively affect habitat preferences of insect predators, but the effects of within-species genotype diversity have not been extensively studied. In a field experiment with different barley (Hordeum vulgare) genotypes in mixed and pure stands, adult seven-spot ladybird Coccinella septempunctata, a polyphagous predator, preferred a specific combination of genotypes over the single genotypes alone before aphids had arrived in the crop, and again when aphids were emigrating. In laboratory experiments on adult ladybird orientation to odour from barley, ladybirds were attracted/arrested by the mixed odour of the same barley genotype mixture that was preferred in the field. Exposure of one barley genotype to volatiles from the other also caused the odour of the exposed plants to become more attractive to ladybirds. The results support the hypothesis that plant volatiles may attract or arrest foraging adult ladybirds, contributing to the selection of favourable habitats, and they show that within-species plant genotype mixing can shape interactions within multitrophic communities.

Aphid acceptance of barley exposed to volatile phytochemicals differs between plants exposed in daylight and darkness.

It is well known that volatile cues from damaged plants may induce resistance in neighboring plants. Much less is known about the effects of volatile interaction between undamaged plants. In this study, barley plants, Hordeum vulgare cv. Kara, were exposed to volatiles from undamaged plants of barley cv. Alva or thistle Cirsium vulgare, and to the volatile phytochemicals, methyl salicylate or methyl jasmonate. Exposures were made either during natural daylight or darkness. Acceptance of exposed plants by the aphid Rhopalosiphum padi was assessed, as well as the expression of putative marker genes for the different treatments. Aphid acceptance of plants exposed to either barley or C. vulgare was significantly reduced, and an effect of the volatiles from undamaged plants was confirmed by the induction of pathogenesis-related protein, PR1a in exposed plants. However the effect on aphid acceptance was seen only when plants were exposed during darkness, whereas PR1a was induced only after treatment during daylight. Aphid acceptance of plants exposed to either methyl salicylate or methyl jasmonate was significantly reduced, but only when plants were exposed to the chemicals during daylight. AOS2 (allene oxide synthase) was induced by methyl jasmonate and BCI-4 (barley chemical inducible gene-4) by methyl salicylate in both daylight and darkness. It is concluded that (a) the effects on aphids of exposing barley to volatile phytochemicals was influenced by the presence or absence of light and (b) the response of barley to methyl salicylate/methyl jasmonate and to volatiles from undamaged plants differed at the gene and herbivore level.

Change in acceptability of barley plants to aphids after exposure to allelochemicals from couch-grass (Elytrigia repens).

The response of the bird cherry-oat aphid, Rhopalosiphum padi, to barley plants was investigated following exposure of the plants to root allelochemicals from the aggressive weed couch-grass, Elytrigia (Agropyron) repens. Plants were treated either with root exudates from living couch-grass plants or with previously identified couch-grass root compounds 15-hydroxyindole-3-acetic acid, DL-5-hydroxytryptophan, L-5-hydroxytryptophan hydrate, and 6-hydroxy-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (carboline)] either separately or in mixtures. In choice and no-choice settling tests, aphid acceptance of barley plants was significantly reduced following treatment with root exudates, and the carboline when tested alone or in combination with the other compounds. In contrast, the other compounds without the carboline were less active in reducing aphid acceptance. In a probing bioassay, individual substances were either neutral or stimulatory to aphids, indicating that the reduced settling was probably not due to direct effects on aphids, but rather due to effects on the plant. This was confirmed in olfactometer assays, in which aphids were repelled by odors from barley plants following treatment with a mixture containing all four chemicals.