Spectral shifted Chebyshev collocation technique with residual power series algorithm for time fractional problems.

In this paper, two problems involving nonlinear time fractional hyperbolic partial differential equations (PDEs) and time fractional pseudo hyperbolic PDEs with nonlocal conditions are presented. Collocation technique for shifted Chebyshev of the second kind with residual power series algorithm (CTSCSK-RPSA) is the main method for solving these problems. Moreover, error analysis theory is provided in detail. Numerical solutions provided using CTSCSK-RPSA are compared with existing techniques in literature. CTSCSK-RPSA is accurate, simple and convenient method for obtaining solutions of linear and nonlinear physical and engineering problems.

A new approach to predict carbonate lithology from well logs: A case study of the Kometan formation in northern Iraq.

Understanding the spatial variation in lithology is crucial for characterizing reservoirs, as it governs the distribution of petrophysical characteristics. This study focuses on predicting the lithology of carbonate rocks (limestone, argillaceous limestone, marly limestone, and marl) within the Kometan Formation, Khabbaz Oil Field, Northern Iraq, using well logs. Precise lithology prediction was achieved by applying multivariate regression method on neutron, sonic, and density logs. Gamma-ray and elemental concentrations from bulk-rock X-ray fluorescence spectroscopy were employed to identify clay minerals, paleoenvironments, and quantify the shale content. The results indicate that the Kometan Formation predominantly comprises limestone, marl, marly limestone, and argillaceous limestone in the middle section. The middle part exhibits a higher shale content compared to the lower and upper parts. A statistically significant correlation (R2 = 0.83-0.85) between described and predicted lithology was established. The model with a higher coefficient of determination (0.85) was tested for further predictions in other wells in the Kirkuk Oil Field. This research can be valuable for lithological and petrophysical characterization of carbonate reservoirs and electrofacies analysis, particularly in situations where core data is unavailable.

Anti-inflammatory effect of high flux dialyzer surface area 2.6m2 in high flux hemodialysis and hemodiafiltration.

Dialysis therapy has remarkably evolved through the innovation in dialyzers and hemodialysis modalities, enhancing patients' quality of life. The efficacy of dialysis can be determined by measuring the reduction ratio (RR) of middle molecules such as Interleukin-6 (IL-6) and Procalcitonin. In our study, we tested a high-flux dialyzer, BIOPURE (Biorema) 260 HF, with a surface area (SA) of 2.6 m2, in terms of IL-6 and Procalcitonin removal while performing high-flux hemodialysis (HF-HD) and post-dilution online hemodiafiltration (OL-HDF). This crossover study comprised 25 patients who received a session of HF-HD using the BIOPURE (Biorema) 260 H, followed by a session of post-dilution OL-HDF. A washout period of 2 weeks was instilled between the two sessions, during which the patients received HF-HD using high-flux dialyzers (maximum SA 2.0 m2). All patients' pre/post dialysis concentrations of IL-6 and procalcitonin were measured. The dialyzer used in this study resulted in a significant IL-6 RR of 44.92±5.11% (p <0.001) with HDF and 32.48±5.72% (p <0.001) with HF-HD; and a procalcitonin RR of 50.32±3.94% (p <0.001) with HDF and 41.80±4.32% (p <0.001) with HF-HD. In conclusion, the dialyzer BIOPURE (Biorema) 260 HF (SA 2.6 m2) is efficient in eliminating IL-6 and procalcitonin, especially with OL-HDF compared to HF-HD, with acceptable albumin loss in the dialysate.

The effect of hemodiafiltration vs. high-flux hemodialysis on alpha 1-microglobulin level and dialysate albumin loss using a dialyzer surface area of 2.6 m².

Dialysis therapy has remarkably evolved through the innovation in dialyzers and hemodialysis modalities, enhancing patients' quality of life. The efficacy of dialysis can be determined by measuring the reduction ratio (RR) of middle molecules, such as alpha 1-microglobulin (A1M). In this study, we tested a high-flux dialyzer, BIOPURE (Biorema) 260 HF, with a surface area (SA) of 2.6 m2, in terms of A1M removal and concurrent albumin loss in dialysate while receiving high-flux hemodialysis (HF-HD) and post-dilution online hemodiafiltration (OL-HDF). This crossover study comprised 25 patients who received a session of HF-HD using the BIOPURE (Biorema) 260 H, followed by a session of post-dilution OL-HDF. A washout period of 2 weeks was instilled between the two sessions, during which the patients received HF-HD using high-flux dialyzers (maximum SA 2.0 m2). All patients' hourly dialysate albumin and pre/post dialysis concentrations of A1M were measured. The dialyzer used in this study resulted in significantly higher A1M RR of 41.9±7.93% with HDF than with HF-HD 27.12±7.65% (p < 0.001), and a median cumulative dialysate albumin loss of 2.97g (IQR 1.98 - 3.37), and 0.67g (IQR 0.49 - 1.13) with HDF and HF-HD, respectively. In conclusion, the dialyzer BIOPURE (Biorema) 260 HF (SA 2.6 m2) is efficient in eliminating A1M, especially with OL-HDF compared to HF-HD, with acceptable albumin loss in the dialysate.

Pathological and ultrastructural studies on anisakis simplex rudolphi-1809 infecting Carangoides bajad with special reference to intestinal maturation in puppies.

Thirty five (70%) of 51 Carangoides bajad were naturally infected with Anisakis simplex during the period from September 2007 to January 2008. The fish were collected from eastern south coast of the Red Sea at Hurgada. The morphological and ultrastructures of Anisakis larvae and adults, and the induced lesions in the fish (intermediate host), five puppies (final host) were orally given infected fish. The body of the larvae is gradually tapering towards the anterior part. It is covered by striated ornamentation longitudinally and horizontally, except the anterior region which is smooth. The morphological and ultrastrutural examinations of the anterior body end of larvae showed a prominent boring tooth, 3 pairs of lips inconspicuous and an excretory ventral pore between the rudimentary subventral lips. The anal end showed a distinct mucron and a slit-shaped anus. The pathological studies revealed encapsulated larvae with concentrical fibrous connective tissue infiltrated, with macrophages and lymphocytes on the surface of liver, spleen and peritoneum of the infected fish. The macrophages aggregated together to form the denser part of the capsule, and invaded the adjacent parenchymal tissue. The hepatocytes, under the affected capsule were necrotic and invaded by melanomacrophages.

Influence of selective media on successful detection of Shiga toxin-producing Escherichia coli in food, fecal, and environmental samples.

Shiga toxin-producing Escherichia coli (STEC) strains have caused a large number of human illness outbreaks worldwide. In most cases, the infection was traced to consumption of meats or vegetables contaminated with cattle feces. To combat this public health problem, pre- and post-harvest control strategies are continuously implemented to assure food safety. Thus, rapid, reliable, and sensitive methods for STEC detection must be available to provide confidence not only in the meats or vegetables entering the food chain but also in testing humans with illnesses. As a result, enrichment for STEC has been a critical step in any successful protocol for their detection. The base media commonly used for STEC enrichment include sorbitol MacConkey agar, tryptic soy broth (TSB), E. coli broth, enterohemorrhagic E. coli broth, buffered peptone water (BPW), and brain heart infusion broth. In addition to bile salts, antibiotics (e.g., tellurite, cefixime, novobiocin, vancomycin, cefsulodin, and acriflavin) are used at different concentrations to enrich for STEC. In most published reports, however, the reasons for choosing the selective medium were not provided. Thus, this review was intended to evaluate the base media and antibiotics commonly used for STEC detection. The efficacy of a detection method will certainly depend on the choice of the base medium, selective agents, and their concentrations. The interactions among these factors are also expected to affect sensitivity of the detection method, especially when the test sample contains a small number of STEC cells. Because sensitivity of detection is expected to decline when testing for stressed or injured STEC cells, as is the case in environmental samples, a pre-enrichment step in TSB or BPW without antibiotics may be necessary. Future research should focus on identifying possible antibiotic combinations that effectively inhibit most background bacteria without affecting pathogenic STEC strains in the test sample.

Clinico-pathological effects of Schistosoma mansoni infection associated with simultaneous exposure to malathion in Swiss outbred albino mice.

To investigate whether infection of Swiss outbred mice with the digenetic fluke Schistosoma mansoni is influenced by exposure to environmental pollutants, experimentally infected mice were exposed to 200 and 400 mg/kg of malathion. Pathology of liver and spleen, worm burden and levels of key hematological, biochemical and liver enzymes parameters of these mice were evaluated and were compared with data from infected, unexposed mice, uninfected, exposed mice as well as with data from uninfected, unexposed mice. Oral administration of malathion to mice infected with 20, 40 or 60 S. mansoni cercariae adversely affect architecture of liver and spleen and critically alter hematological, biochemical, histological and hepatic enzymes parameters significantly more than the controls. Alterations observed in infected, exposed mice included (i) higher mortality rate; (ii) severe pathologies in liver and spleen; (iii) increased serum level of bilirubin and alanine aminotransferase/aspartate aminotransferase (ALT/AST) enzymes; (iv) decreased serum level of albumin and total proteins; and (v) decreased red blood cell count (RBC), lymphocytes, leucocytic count, and hemoglobin content. The number of recovered adult worms of S. mansoni or their oviposition capacity did not seem to be affected with malathion treatment. Statistical analysis revealed that the increase alteration in hepatic functions is correlated with increasing the number of S. mansoni cercariae and malathion doses. Such alterations were more significant in mice treated with the higher dose of malathion or infected with the largest numbers of S. mansoni cercariae. These data indicate that schistosomiasis can be exacerbated by simultaneous malathion exposure, which in turn adversely impact the clinical and pathological outcome of the disease.

Growth and enrichment medium for detection and isolation of Shiga toxin-producing Escherichia coli in cattle feces.

Detection methods of Shiga toxin-producing Escherichia coli (STEC) in cattle feces varied in using enrichment media containing different antibiotic combinations. To examine efficacy of a new detection method for STEC, three O157:H7 (ATCC 43889, 43890, and 43895) and 41 non-O157:H7 (members of the O1, O15, O26, O86, O103, O111, O125, O127, O128, O136, O146, O153, O158, O165, O166, and O169 serogroups) isolates were tested. These isolates were grown in tryptic soy broth for 6 h, and their concentrations were determined before inoculation of tubes containing 1 g of cattle feces (sterile [experiment 1; evaluating growth] and fresh [experiment 2; evaluating enrichment]) to simulate the high and low levels of STEC shedding by cattle (10(5) versus 102 CFU/g feces, respectively). Eight STEC isolates (the three O157:H7 and five non-O157:H7 selected at random) were tested at a very low level (10 CFU/g feces). The feces were incubated in 50 ml of brain heart infusion broth containing potassium tellurite, novobiocin, and vancomycin (2.5, 20, and 40 mg/liter, respectively) and cefixime (50 microg/liter) at 37 degrees C for 12 h and tested for STEC (VTEC [verotoxin-producing E. coli]-Screen assay [agglutination immunoassay]). Potential STEC isolates were recovered, characterized biochemically, serotyped, and tested for toxin production using Vero (African green monkey kidney) cell toxicity assay and agglutination immunoassay. In both experiments, all the STEC isolates used for fecal inoculation were recovered at the concentrations tested. Our medium supported growth of and enrichment for a wide range of STEC isolates.

Observations on besnoitiosis in Virginia opossum (Didelphis virginiana) from Michigan, USA.

Besnoitia tissue cysts were found in five naturally-infected adult opossums (Didelphis virginiana) from Michigan. Details of the microscopy, histopathology, ultra-structure, and genetic features of the cysts were studied to identify their species-specific traits. The materials were differentiated phenotypically from cysts of other Besnoitia spp. by difference in size, pattern of tissue distribution, morphology of pellicle and nucleus, number of micronemes and rhoptries, amount of lipids and amylopectin, and presence of enigmatic bodies. Morphometric variations identified the tissue cysts and the pathologic changes in opossums host to be due to B. darlingi. The data were proved by phylogenetic analysis based on DNA sequences of the first internal transcribed spacer of nuclear rDNA. Cluster analysis showed that B. darlingi was distinct from all other Besnoitia spp. as two distinct phylogenetic clades: I- included Besnoitia spp. described from opossum (B. darlingi), sheep (B. jellisoni), rodent (B. akadoni) and rabbit (B. oryctofelisi) and clade II- encompassed parasites described from cattle (B. besnoiti), equids (B. bennetti) and reindeer (B. tarandi). The genetic attributed particular to the genus Besnoitia complemented the morphologica features and lead to accurate delimitation of Besnoitia species.

Phytoremediation of mercury and organomercurials in chloroplast transgenic plants: enhanced root uptake, translocation to shoots, and volatilization.

Transgenic tobacco plants engineered with bacterial merA and merB genes via the chloroplast genome were investigated to study the uptake, translocation of different forms of mercury (Hg) from roots to shoots, and their volatilization. Untransformed plants, regardless of the form of Hg supplied, reached a saturation point at 200 microM of phenylmercuric acetate (PMA) or HgCl2, accumulating Hg concentrations up to 500 microg g(-1) with significant reduction in growth. In contrast, chloroplast transgenic lines continued to grow well with Hg concentrations in root tissues up to 2000 microg g(-1). Chloroplasttransgenic lines accumulated both the organic and inorganic Hg forms to levels surpassing the concentrations found in the soil. The organic-Hg form was absorbed and translocated more efficiently than the inorganic-Hg form in transgenic lines, whereas no such difference was observed in untransformed plants. Chloroplast-transgenic lines showed about 100-fold increase in the efficiency of Hg accumulation in shoots compared to untransformed plants. This is the first report of such high levels of Hg accumulation in green leaves or tissues. Transgenic plants attained a maximum rate of elemental-Hg volatilization in two days when supplied with PMA and in three days when supplied with inorganic-Hg, attaining complete volatilization within a week. The combined expression of merAB via the chloroplast genome enhanced conversion of Hg2+ into Hg,0 conferred tolerance by rapid volatilization and increased uptake of different forms of mercury, surpassing the concentrations found in the soil. These investigations provide novel insights for improvement of plant tolerance and detoxification of mercury.

Metal accumulation in eggs of the red-eared slider (Trachemys scripta elegans) in the Lower Illinois River.

The Illinois River is a highly utilized navigable waterway in the US Midwest, and has historically been contaminated with metal toxicants from various industrial and municipal pollution sources. Little information on metal contamination is available in the Lower Illinois River, and in particular, in the habitat of the red-eared slider (Trachemys scripta elegans) at the southern end of the river near Grafton, IL. This study was conducted to determine current levels of metal contamination in water, sediment, soil, and plants in the habitat, as well as to reveal temporal and spatial variations of metal accumulation in eggs of the red-eared slider. Aluminum, Cd, Cr, Cu, Mn, Ni, Pb, V, Sn, and Zn were analyzed by inductively-coupled plasma spectroscopy. High concentrations of metals were observed in lake sediment, compared with the concentrations in water, soil, and plant tissues. Sediment Ni concentrations (mg kg(-1)) varied from 66 to 95 and Sn from 1100 to 1600. Five detectable metals in egg content were Zn (24.2 +/- 13), Al (2.2 +/- 1.2), Sn (1.8 +/- 1.1), Mn (1.1 +/- 0.6), and Cu (0.9 +/- 0.5); nine detectable metals in egg shell were Zn (6.8 +/- 3.9), Sn (3.7 +/- 3.1), Cu (1.9 +/- 1.3), Cr (1.6 +/- 1.5), V (1.6 +/- 1.4), Pb (1.3 +/- 0.7), Ni (1.3 +/- 0.9), Mn (1.0 +/- 0.8), and Cd (0.16 +/- 0.11). Zinc accumulation in egg content was significantly correlated with Zn in egg shell (r = 0.445, P < 0.002, n = 42). While significant spatial variation was observed in egg shell, metal accumulation in eggs (content and shell) collected from the same ground of turtles consecutively for 4 years did not show a significant temporal change.

Prevalence of Shiga toxin-producing Escherichia coli in beef cattle.

A large number of Shiga toxin-producing Escherichia coli (STEC) strains have caused major outbreaks and sporadic cases of human illnesses, including mild diarrhea, bloody diarrhea, hemorrhagic colitis, and the life-threatening hemolytic uremic syndrome. These illnesses have been traced to both O157 and non-O157 STEC. In a large number of STEC-associated outbreaks, the infections were attributed to consumption of ground beef or other beef products contaminated with cattle feces. Thus, beef cattle are considered reservoirs of STEC and can pose significant health risks to humans. The global nature of the human food supply suggests that safety concerns with beef will continue and the challenges facing the beef industry will increase at the production and processing levels. To be prepared to address these concerns and challenges, it is critical to assess the role of beef cattle in human STEC infections. In this review, published reports on STEC in beef cattle were evaluated to achieve the following specific objectives: (i) assess the prevalence of STEC in beef cattle, and (ii) determine the potential health risks of STEC strains from beef cattle. The latter objective is critically important because many beef STEC isolates are highly virulent. Global testing of beef cattle feces revealed wide ranges of prevalence rates for O157 STEC (i.e., 0.2 to 27.8%) and non-O157 STEC (i.e., 2.1 to 70.1%). Of the 261 STEC serotypes found in beef cattle, 44 cause hemolytic uremic syndrome and 37 cause other illnesses.

Shiga toxin-producing Escherichia coli: pre- and postharvest control measures to ensure safety of dairy cattle products.

The large number of cases of human illness caused by Shiga toxin-producing Escherichia coli (STEC) worldwide has raised safety concerns for foods of bovine origin. These human illnesses include diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura. Severe cases end with chronic renal failure, chronic nervous system deficiencies, and death. Over 100 STEC serotypes, including E. coli O157:H7, are known to cause these illnesses and to be shed in cattle feces. Thus, cattle are considered reservoirs of these foodborne pathogens. Because beef and dairy products were responsible for a large number of STEC outbreaks, efforts have been devoted to developing and implementing control measures that assure safety of foods derived from dairy cattle. These efforts should reduce consumers' safety concerns and support a competitive dairy industry at the production and processing levels. The efficacy of control measures both before harvest (i.e., on-farm management practices) and after harvest (i.e., milk processing and meat packing) for decreasing the risk of STEC contamination of dairy products was evaluated. The preharvest measures included sanitation during milking and management practices designed to decrease STEC prevalence in the dairy herd (i.e., animal factors, manure handling, drinking water, and both feeds and feeding). The postharvest measures included the practices or treatments that could be implemented during processing of milk, beef, or their products to eliminate or minimize STEC contamination.

Phytoremediation of organomercurial compounds via chloroplast genetic engineering.

Mercury (Hg), especially in organic form, is a highly toxic pollutant affecting plants, animals, and man. In plants, the primary target of Hg damage is the chloroplast; Hg inhibits electron transport and photosynthesis. In the present study, chloroplast genetic engineering is used for the first time to our knowledge to enhance the capacity of plants for phytoremediation. This was achieved by integrating a native operon containing the merA and merB genes (without any codon modification), which code for mercuric ion reductase (merA) and organomercurial lyase (merB), respectively, into the chloroplast genome in a single transformation event. Stable integration of the merAB operon into the chloroplast genome resulted in high levels of tolerance to the organomercurial compound, phenylmercuric acetate (PMA) when grown in soil containing up to 400 micro M PMA; plant dry weights of the chloroplast transformed lines were significantly higher than those of wild type at 100, 200, and 400 micro M PMA. That the merAB operon was stably integrated into the chloroplast genome was confirmed by polymerase chain reaction and Southern-blot analyses. Northern-blot analyses revealed stable transcripts that were independent of the presence or absence of a 3'-untranslated region downstream of the coding sequence. The merAB dicistron was the more abundant transcript, but less abundant monocistrons were also observed, showing that specific processing occurs between transgenes. The use of chloroplast transformation to enhance Hg phytoremediation is particularly beneficial because it prevents the escape of transgenes via pollen to related weeds or crops and there is no need for codon optimization to improve transgene expression. Chloroplast transformation may also have application to other metals that affect chloroplast function.

Hammondia heydorni from the Arabian mountain gazelle and red fox in Saudi Arabia.

Unsporulated oocysts were detected in the feces of an Arabian red fox (Vulpes vulpes arabica) between 6 and 8 days after it had been fed meat from Arabian mountain gazelles (Gazella gazella) known to contain sarcocysts. No oocysts were discovered in the feces of other experimental cubs, although sporocysts of Sarcocystis spp. were passed subsequently by all cubs that were fed gazelle meat, including those fed with reem (G. subgutturosa marica). The oocysts sporulated in 3 days at room temperature (25 +/- 2 C); they were 10.9 +/- 1.4 x 10.1 +/- 1.3 microm, with 2 sporocysts measuring 6.0 +/- 0.6 x 4.7 +/- 0.8 microm, each with 4 sporozoites. Sporulated oocysts were identified as those of Hammondia heydorni using molecular and standard morphometric techniques. Sequence differences between 2 fox and 3 dog isolates of H. heydorni were detected and allowed differentiation between the 2 populations of the organism. The involvement of Neospora caninum was excluded using molecular methods. The Arabian red fox and the Arabian mountain gazelle in Saudi Arabia are new, definitive and intermediate hosts for H. heydorni.

Introduction to the food safety concerns of verotoxin-producing Escherichia coli.

Verotoxin-producing Escherichia coli (VTEC) have emerged in the past two decades as food-borne pathogens that can cause major outbreaks of human illnesses worldwide. The number of outbreaks has increased in recent years due to changes in food production and processing systems, eating habits, microbial adaptation, and methods of VTEC transmission. The human illnesses range from mild diarrhea to hemolytic uremic syndrome (HUS) that can lead to death. The VTEC outbreaks have been attributed to O157:H7 and non-O157:H7 serotypes of E. coli. These E. coli serotypes include motile (e.g., O26:H11 and O104:H21) and nonmotile (e.g., O111:H-, O145:H-, and O157:H-) strains. In the United States, E. coli O157:H7 has been the major cause of VTEC outbreaks. Worldwide, however, non-O157:H7 VTEC (e.g., members of the O26, O103, O111, O118, O145, and O166 serogroups) have caused approximately 30% of the HUS cases in the past decade. Because large numbers of the VTEC outbreaks have been attributed to consumption of ruminant products (e.g., ground beef), cattle and sheep are considered reservoirs of these food-borne pathogens. Because of the food safety concern of VTEC, a global perspective on this problem is addressed (Exp Biol Med Vol. 228, No. 4). The first objective was to evaluate the known non-O157:H7 VTEC strains and the limitations associated with their detection and characterization. The second objective was to identify the VTEC serotypes associated with outbreaks of human illnesses and to provide critical evaluation of their virulence. The third objective was to determine the rumen effect on survival of E. coli O157:H7 as a VTEC model. The fourth objective was to explore the role of intimins in promoting attaching and effacing lesions in humans. Finally, the ability of VTEC to cause persistent infections in cattle was evaluated.

Verotoxin-producing Escherichia coli in culled beef cows grazing rangeland forages.

The objective of this study was to assess prevalence of verotoxin-producing Escherichia coli (VTEC) in culled beef cows at the time of shipping to slaughter. Feces were collected from 82 cows on eight Nevada ranches during fall and winter (from September to January) after grazing rangeland forages. A random sample (n = 154) of potential VTEC isolates were tested for verotoxicity and were screened for the presence (polymerase chain reaction) and expression (VTEC-reversed passive latex agglutination assay) of the toxin genes (i.e., VT1 and VT2). Seventeen isolates from four ranches were VTEC. Of these, four had the VT1 gene, five had the VT2 gene, seven had both genes, and one did not have either gene despite its toxicity to Vero cells. Except for one isolate (i.e., untypeable that reacted with VT1-latex beads without having VT1 gene), the genotype and phenotype data of the VTEC isolates matched. Another isolate (O8:H- [nonmotile]) was verotoxic, but neither had nor expressed the toxin genes. Of the 17 isolates, four (from one cow) were O157:H7, 11 (from five cows on three ranches) were non-O157:H7 (two O8:H-, three O105:H-, three O116:H-, and three O141:H-), and two were untypeable. Because some of these VTEC serotypes (i.e., O8:H-, O141:H-, and O157:H7) are known to cause human illnesses, it is beneficial to identify VTEC-positive cows before slaughter. This is a critical step in any pre- or post-harvest strategy to minimize the risk of beef contamination with such pathogens.

Verotoxin-producing Escherichia coli in sheep grazing an irrigated pasture or arid rangeland forages.

Worldwide, verotoxin-producing Escherichia coli (VTEC) have been recognized as the cause of many sporadic cases or major outbreaks of human illnesses involving consumption of contaminated meat, especially beef. Although sheep products have not been linked to reported human illnesses, their role as a food safety risk factor should not be ignored. The objective of this study was to assess VTEC prevalence in two groups of ewes (20 each) grazing an irrigated pasture or arid range in a western United States environment (Nevada) over 1 year (summer of 1999 to summer of 2000). A random sample (n = 504) of potential VTEC isolates were tested for verotoxicity and were screened for the presence (polymerase chain reaction [PCR]) and expression (VTEC-reversed passive latex agglutination assay) of the toxin genes (i.e., VT1 and VT2). Forty-one VTEC isolates (16 having only the VT1 gene and 25 having both VT1 And VT2 genes) were detected in both groups of ewes. Except for seven isolates, the genotype and phenotype data matched. All the isolates (nonmotile [H-]) were non-O157:H7 VTEC (i.e., O91:H- [n = 25], O128:H- [n = 9], and untypeable ones [n = 7]). More infected ewes (nine versus three) and different VTEC strains were found in the irrigated pasture than in the arid range. Because our ewes were shedding two VTEC serotypes known to cause human illnesses, it is beneficial to identify VTEC-positive sheep before slaughter as an initial control point before entering the food chain.

Influence of pH treatments on survival of Escherichia coli O157:H7 in continuous cultures of rumen contents.

The pH (i.e., 5.5, 5.75, 6.0, 6.25, 6.5, 6.75, 7.0, and 7.25) effect on Escherichia coli O157:H7 in an artificial rumen model was investigated. Eight fermenters were inoculated with bovine rumen fluid and were supplied with a diet (75 g of dry matter daily in 12 equal portions [every 2 hr]) containing similar forage-to-concentrate ratio. After an adaptation period (i.e., 3 days for adjusting the rumen fluid [pH 6.2] microbial population to the test pH and 4 days for adjustment to the diet at the test pH), each fermenter was inoculated with 10(9) cells of E. coli O157:H7. Samples were collected hourly for 12 hr and every 2 hr for an additional 12 hr and were analyzed by flow cytometer. E. coli O157:H7 could not be quantified after 24 hr, and detection was only possible after enrichment. Because the pathogen could not be detected 5 days postinoculation (i.e., Day 13), the fermenters were reinoculated with E. coli O157:H7 on Days 17 and 22. E. coli O157:H7 numbers decreased from 10(6) to 10(4)/ml of fermenter contents in a quadratic (P < 0.05) fashion over the 24-hr sampling period, and the rate of reduction was slower (P < 0.05) for pH 7.0 than for other pH treatments. Results suggested that E. coli O157:H7 population were decreased by competitive exclusion and were not affected by culture pH.

Phytomonitoring the unique colonization of oil-contaminated saline environment by Limoniastrum monopetalum (L.) Boiss in Egypt.

A site that covers over 20 acres of coastal saline depression in the western Mediterranean coastal desert of Egypt (El-Hammra station, the main crude oil pipeline terminal in Al-Alamein) is contaminated with crude oil spill as a result of activities from refineries, oilfield blowouts, tanker and pipeline break-ups. This area, prior to contamination, was dominated by different common halophytes. However, Limoniastrum monopetalum is now the only species found growing in the oil-contaminated soil. A specific question addressed in the present study was: what are the biochemical changes occurring in a desert plant growing in oil-contaminated soils? Major metabolites such as proline, betaine, free amino acids, fatty acid esters and mineral elements were studied. The plant samples were collected from the oil-contaminated, as well as noncontaminated, sites. The higher concentration in the selected organic metabolites in the plants growing in the contaminated site compared to those in noncontaminated site may be due to differences in a number of receptors. The sensitivity of such receptors for the environmental signal that cause differences in genetic expression leads to differences in physiological processes. The change in the landscape of the contaminated area and the elimination of the natural vegetation, except L. monopetalum, may explain the competitive balance toward the oil-resistant species.