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Biomedical subjects

G Bitton

Publications and source records attributed to G Bitton.

At least 19 recordsLinked to original sources
PubMed2000

[Intestinal parasitosis and environmental pollution: 1343 pediatric cases in Beni-Mellal, Morocco].

This study was undertaken to determine the possible health risk associated with raw wastewater use in agricultural purposes, particularly, the transmission of parasite infections among children of five regions in Beni-Mellal, Morocco. In a randomly-selected sample of 1343 children, 740 of them were from five regions using raw wastewater for agriculture, and 603 were from 4 control regions that do not practice wastewater irrigation. One or more parasite infections were identified in 50.8% of the children living in the wastewater re-use regions and in 8.2% only of the others. The seven parasites identified were Entamoeba histolytica, Giardia intestinalis, Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, Hymenolepis nana, Taenia saginata, which infected 34.3%, 5.1%, 20.5%, 0.4%, 5.2%, 7.2%, 0.5% in the exposed population and 4.3%, 0.3%, 3.8%, 0.3%, 1.0%, 0.6% and 0.0% in the control population respectively. In conclusion, raw wastewater use in Beni-Mellal lead to a high risk of parasite infections. Adequate treatment of wastewater is highly recommended.

Agriculture↗
PubMed1999

Determination of the heavy metal binding capacity of aquatic samples using MetPLATE: a preliminary study.

MetPLATE, a microbial toxicity test which is specific for heavy metal toxicity, was used to rapidly determine the heavy metal binding capacity (HMBC) of a wide range of surface waters from Florida and Georgia. HMBC determines the impact of physicochemical factors on metal bioavailability and toxicity. The new developed protocol, using MetPLATE as the toxicity assay, showed that HMBC varied from 1.7 to 39.2 for Cd whereas the ranges for Cu and Ag were < 1-11.9 and < 1-2.1, respectively. The effect of seasons on HMBC was determined using samples from the Hogtown Creek, Gainesville, FL, and from the St John's river in Jacksonville, FL. Both surface waters displayed the highest HMBC during the Fall season. Preliminary examination of the limited data set confirms that HMBC may be influenced by the concentration of dissolved organic carbon (DOC). These preliminary data show that the impact of physical and chemical parameters on the toxicity of metals in aquatic environments can be rapidly assessed using rapid and low-cost microbiotests.

Biological Availability↗
PubMed1999

Assessment of metal content and toxicity of leachates from teapots.

Metallic teapots traditionally used in Morocco were investigated for release of toxic metals from the teapots and their toxicity, as determined by MetPAD, a bacterial toxicity test that is specific for heavy metal toxicity. Our data show that some teapots were non-toxic while a few others were highly toxic, as shown by MetPAD. Tea addition reduced somewhat heavy metal toxicity due possibly to the complexing ability of tea. Chemical analysis of teapot leachates showed that some contained zinc and copper. Teapot No. 5, which showed the highest toxicity, also displayed the highest Zn concentration (7.39 mg/l), confirming the toxicity data. Based on estimates of tea consumption in Morocco, we showed that the extra daily burden of Zn ranged from 1.75 to 4.2 mg/day, assuming the maximum zinc concentration of 7.4 mg/l, as found in our study. This represents 3.5-8% of the LOAEL for zinc of 50 mg/day and would not be important as compared to other sources zinc intake.

Chromium↗
PubMed1999

Helminthic infections associated with the use of raw wastewater for agricultural purposes in Beni Mellal, Morocco.

We aimed to determine the possible risks associated with raw wastewater use for agricultural purposes, particularly the transmission of helminthic infections among children. In a randomly-selected sample of 1343 children, 740 of them were from five regions using raw wastewater for agriculture, while 603 were from four control regions that do not use such water. The prevalence of helminthic infection was found to be significantly higher among children in regions using wastewater, compared to control regions. Behavioural characteristics and public water supply were found to be associated with higher infection rates. Adequate treatment of wastewater as well as public health education are highly recommended.

Adolescent↗
PubMed1995

Heavy metal toxicity testing in environmental samples.

The toxicity of heavy metals in the environment depends on a number of physicochemical and biological factors. The complexity of these relationships has encouraged the use of bioassays for direct measurement of the [table: see text] impact of toxic metals on selected test species. Fish and daphnid bioassays are well accepted by the scientific and regulatory communities, but their length (48 h or more) and the considerable time and effort needed to culture the test organisms make their application to sample screening problematical. Microbial and biochemical assays based on the inhibition of bioluminescence, enzyme activity, enzyme biosynthesis, growth, respiration, and heat production are typically faster and less expensive than the traditional and fish bioassays. Some of these tests approach or equal the sensitivity of daphnids to heavy metals. Since the soil acts as a sink for airborne and waste-applied metals, the uptake of metals by plants and the associated toxic impacts are important. Growth inhibition, enzyme induction, and production of stress proteins have been considered as toxicity end points. Enzymatic tests have been developed that are specific for heavy metal toxicity. Such tests can facilitate toxicity reduction evaluations. Detection of individual metals in the environment may eventually be possible using biosensors consisting of genetically engineered microorganisms. Direct solid-phase tests for soil, sediment, or sludge toxicity, using bacterial bioluminescence or enzyme activity as end points, have been developed. Such tests may complement traditional solid-phase toxicity tests using nematodes or earthworms as indicator organisms. Based on the work reviewed, we draw the following conclusions: 1. The Microtox assay is sensitive to mercury but would fail to detect the toxicity of certain metals, such as cadmium. Among all the microbial assays reviewed, the bioassay based on growth inhibition of the alga Selenastrum capricornutum appears to give the lowest EC50s, similar to those seen for daphnid bioassays. 2. Biosensors, using genetically engineered microorganisms, offer an elegant means of detecting the presence of specific heavy metals in environmental samples. However, at the present time, they are not designed for assessing heavy metal toxicity. 3. The use of bioassays specific for heavy metal toxicity can be useful for directly assessing the bioavailability of these toxicants in environmental samples, thus avoiding the need for fractionation.+4

Animals↗
PubMed1995

Development and application of a monoclonal antibody against Thiothrix spp.

Historically, methods used to identify Thiothrix spp. in environmental samples have been inadequate because isolation and identification procedures are time-consuming and often fail to separate Thiothrix spp. from other filamentous microorganisms. We described a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) procedure which was used to identify Thiothrix spp. in wastewater, artesian springs, groundwater, and underwater subterranean samples. The ELISA utilized monoclonal antibody T3511 to a species-specific carbohydrate epitope of Thiothrix spp. No cross-reactions were observed among non-Thiothrix strains consisting of 12 species and nine genera. In field trials, the ELISA identified 100% of 20 biochemically and cytologically confirmed Thiothrix spp.-containing samples with no false positives. Indirect immunofluorescent microscopy utilizing T3511 was effective for wastewater samples but not for those from natural spring water because of background fluorescence in the latter. In addition, electron micrographs of Thiothrix spp. labeled with T3511-biotin-anti-mouse antibody-gold showed that epitope T3511 was intracellular both in laboratory strains and environmental isolates. The minimum level of detection of the ELISA was 0.10 microgram/ml.

Antibodies, Bacterial↗
PubMed1994

Evaluation of a microplate assay specific for heavy metal toxicity.

A rapid, quantitative microbial assay, which is specific for heavy metal toxicity, has been developed. The assay (MetPLATE) is in a 96-well microtitration plate format and is suitable for determining toxicity characteristics such as median inhibitory concentrations. The sensitivity of MetPLATE to heavy metals [Cu, Zn, Cd, Pb, Hg, Cr(III)] was generally higher than Microtox and was of the same order as or better than Daphnia and fish bioassay. MetPLATE was insensitive to organic compounds at concentrations higher than those found in the environment. Six out of 10 industrial wastewaters or process waters surveyed were toxic. Heavy metal analysis of these waters confirmed the presence of heavy metals in the toxic samples. MetPLATE can be run concurrently with other assays for general toxicity to help determine the nature of chemicals causing toxicity.

Animals↗
PubMed1992

Detection of Salmonella enteritidis in environmental samples by monoclonal antibody-based ELISA.

We have developed a enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (ASCII) for the detection of Salmonella enteritidis in environmental samples. ELISA was used to test for sensitivity and specificity of ASCII. 38 other species of bacteria, including 31 Salmonella species were included in cross-reactivity testing with ELISA. ASCII showed no reactivity with any other species tested. ASCII was found to be an IgG1 specific for S. enteritidis lipopolysaccharide (LPS). The lower limits for S. enteritidis detection was 10(5) cells/ml for pure cultures and in 10% sludge (w/v). Environmental samples (raw wastewater, wastewater effluents, mixed liquor and aerobically digested sludge) were obtained twice from five sites and ELISA tested for the presence of S. enteritidis. ELISA results compared to the American Public Health Association (APHA) method of Salmonella detection were not significantly different (P greater than 0.05). The ELISA took 24 h for completion compared to 96-120 h for the APHA procedure. Results demonstrate the reliability of the ELISA and, more importantly, provides a rapid means of detection of S. enteritidis in environmental samples.

Animals↗
PubMed1992

Bacterial and enzymatic bioassays for toxicity testing in the environment.

Microbioassays using bacteria or enzymes are increasingly applied to measure chemical toxicity in the environment. Attractive features of these assays may include low cost, rapid response to toxicants, high sample throughput, modest laboratory equipment and space requirements, low sample volume, portability, and reproducible responses. Enzymatic tests rely on measurement of either enzyme activity or enzyme biosynthesis. Dehydrogenases are the enzymes most used in toxicity testing. Assay of dehydrogenase activity is conveniently carried out using oxidoreduction dyes such as tetrazolium salts. Other enzyme activity tests utilize ATPases, esterases, phosphatases, urease, luciferase, beta-galactosidase, protease, amylase, or beta-glucosidase. Recently, the inhibition of enzyme (beta-galactosidase, tryptophanase, alpha-glucosidase) biosynthesis has been explored as a basis for toxicity testing. Enzyme biosynthesis was found to be generally more sensitive to organic chemicals than enzyme activity. Bacterial toxicity tests are based on bioluminescence, motility, growth, viability, ATP, oxygen uptake, nitrification, or heat production. An important aspect of bacterial tests is the permeability of cells to environmental toxicants, particularly organic chemicals of hydrophobic nature. Physical, chemical, and genetic alterations of the outer membrane of E. coli have been found to affect test sensitivity to organic toxicants. Several microbioassays are now commercially available. The names of the assays and their basis are: Microtox (bioluminescence), Polytox (respiration), ECHA Biocide Monitor (dehydrogenase activity), Toxi-Chromotest (enzyme biosynthesis), and MetPAD (enzyme activity). An important feature common to these tests is the provision of standardized cultures of bacteria in freeze-dried form. Two of the more recent applications of microbioassays are in sediment toxicity testing and toxicity reduction evaluation. Sediment pore water may be assayed directly or solvents may be used to extract the toxicants. Some of the solvents used for extraction of organic chemicals are themselves toxic to bacteria (e.g., dichloromethane), requiring exchange with a less toxic solvent (e.g., ethanol, methanol, DMSO). A modification of the Microtox test allows direct assay of solid-phase samples such as sediments. The toxicity reduction evaluation (TRE) must be carried out at wastewater treatment plants whose effluents fail toxicity standards. The TREs require numerous and repeated toxicity assays, thus favoring application of microbioassays. Presently, no single microbioassay can detect all categories of environmental toxicants with equal sensitivity. Therefore, a battery of tests approach is recommended. The differential sensitivity of alternative tests may, in fact, be exploited. Further research is needed to construct strains of genetically engineered microorganisms or isolate microorganisms or enzymes that respond to specific classes of toxicants. These can be combined into batteries appropriate for different environments or test objectives.

Bacteria↗
PubMed1991

Detection of nucleic acids homologous to human immunodeficiency virus in wastewater.

Raw wastewaters were obtained from the cities of Belle Glade, Ocala and Gainesville in the state of Florida and were concentrated using several established methods for the recovery of human enteroviruses. The nucleic acids were then extracted from the wastewater concentrates, suspended in 2 x SSC with and without 2 N NaOH (for the detection of DNA and both DNA and RNA, respectively), and dot blotted onto hybridization membranes. These membranes were then hybridized with three 32P-end-labeled 18-mer oligonucleotides directed against the LTR, gag, and env regions of the human immunodeficiency virus type 1 (HIV-1). Autoradiographic analyses of these blots indicate that sequences homologous to HIV-1 genomic RNA and proviral DNA were found in Belle Glade wastewater but not in wastewater from Ocala and Gainesville. These findings may have implications in the wastewater treatment system as well as for detection of HIV-1 in clinical samples.

Base Sequence↗
PubMed1991

Development and application of new positively charged filters for recovery of bacteriophages from water.

Electronegative and electropositive filters were compared for the recovery of indigenous bacteriophages from water samples, using the VIRADEL technique. Fiber glass and diatomaceous earth filters displayed low adsorption and recovery, but an important increase of the adsorption percentage was observed when the filters were treated with cationic polymers (about 99% adsorption). A new methodology of virus elution was developed in this study, consisting of the slow passage of the eluent through the filter, thus increasing the contact time between eluent and virus adsorbed on the filters. The use of this technique allows a maximum recovery of 71.2% compared with 46.7% phage recovery obtained by the standard elution procedure. High percentages (over 83%) of phage adsorption were obtained with different filters from 1-liter aliquots of the samples, except for Virosorb 1-MDS filters (between 1.6 and 32% phage adsorption). Phage recovery by using the slow passing of the eluent depended on the filter type, with recovery ranging between 1.6% for Virosorb 1-MDS filters treated with polyethyleneimine and 103.2% for diatomaceous earth filters treated with 0.1% Nalco.

Adsorption↗
PubMed1990

Enhancement of enterovirus infectivity in vitro by pretreating host cell monolayers with the cationic polymer polyethyleneimine.

Laboratory strains of enteroviruses, as well as viruses isolated from raw wastewater, were found to exhibit enhanced infectivity in vitro when BGM cell monolayers were pretreated with the cationic polymer polyethyleneimine (PEI). Viruses were assayed by the cytopathic effect technique and as PFU under methylcellulose and agar overlays with monolayers treated with 0 to 5.0 x 10(-3)% (wt/vol) PEI in phosphate-buffered saline supplemented with 2% fetal bovine serum. Poliovirus type 1 cytopathic effect occurred at an enhanced rate in cells treated with 5.0 x 10(-3)% PEI compared with untreated cells. PEI-treated cells were found to adsorb viruses much more effectively than untreated cells did. When the methylcellulose overlay procedure was used, rates of infectivity were enhanced as follows: poliovirus type 1, 5.5-fold; echovirus type 1, 1.2-fold; echovirus type 5, 5.2-fold; and coxsackievirus type B5, 4.9-fold. Viruses concentrated from raw wastewater showed a 3.8-fold increase in titer when quantitated by the most-probable-number method and a 3.3-fold increase when quantitated as PFU under an agar overlay.

Animals↗
PubMed1990

Microcosm for assessing survival of genetically engineered microorganisms in aquatic environments.

Laboratory-contained microcosms are important for studying the fate and survival of genetically engineered microorganisms. In this study, we describe a simple aquatic microcosm that utilizes survival chambers in a flowthrough or static renewal system. The model was used to study the survival of genetically engineered and wild-type strains of Escherichia coli and Pseudomonas putida in the lake water environment. Temperature-dependent studies indicated that the genetically engineered microorganisms survived better or at least as well as their wild-type counterparts at 15, 25, and 30 degrees C. The genetic determinants of the genetically engineered microorganisms also remained fairly stable within the host cell under the tested conditions. In the presence of organisms indigenous to lake water, E. coli was eliminated after 20 days, whereas P. putida showed an initial decline but was able to stabilize its population after 5 days. A herbicide, Hydrothol-191, caused a significant decline in numbers of P. putida, but no significant difference was observed between the genetically engineered microorganisms and the wild-type strain. The microcosm described is simple, can be easily adapted to study a variety of environmental variables, and has the advantage that the organisms tested are constantly exposed to test waters that are continuously renewed.

Dicarboxylic Acids↗