Striped weakfish (Cynoscion guatucupa): a biomonitor of organochlorine pesticides in estuarine and near-coastal zones.

The general goal of this study was to investigate the role of Cynoscion guatucupa as a biomonitor of organochlorine pesticides (OCP) contamination in Bahía Blanca estuary. Thus, we evaluated whether or not OCP fish distribution pattern reflects the OCP land sources, and if size-related bioaccumulation and biomagnification of these contaminants does occur by comparing different tissues of juvenile and adults of C. guatucupa (Cuvier, 1830). Size-related bioaccumulation in C. guatucupa was observed and it was more important for the more lipophilic and biomagnifying OCP, being determined over time by diet influence. Endosulfan sulfate, chlordanes, HCH isomers and DDT compounds predominated in tissues and ingested food of C. guatucupa, being alpha-chlordane, heptachlor and p,p'-DDE highly bioaccumulated and biomagnificated. Our findings also showed that male adults of C. guatucupa are biomonitors of OCP pollution so we propose this species for further investigations in other coastal zones of South America.

Effects of capsule endoscopy on cardiac pacemakers.

BACKGROUND AND STUDY AIMS: Capsule endoscopy is a new, noninvasive diagnostic technique which enables visualization of the mucosa of the small intestine in physiological conditions and without the need to subject the patient to external radiation. Wireless capsule video endoscopy is contraindicated in patients with a cardiac pacemaker. However, on the basis of the characteristics of the radiofrequency band used by the endoscopic capsule, together with a series of other factors, it is possible that the patient's use of a pacemaker should not be a contraindication to capsule endoscopy. PATIENTS AND METHODS: This work had two phases: an in vitro study, using an interference detector, and an in vivo study involving 20 patients with cardiac pacemakers who showed symptoms or signs that justified a capsule endoscopy investigation. RESULTS: No interference was observed during the first, in vitro, phase of the study. In the second phase, patients wore a Holter recorder for a mean time of 10 hours, during which the average number of recorded QRS complexes exceeded 30,000. All the pacemakers functioned normally. Interference due only to myopotentials was detected in a single patient in whom modification of the pacemaker programming was necessary. In the other 19 patients, neither sensing nor stimulation failures were observed. CONCLUSIONS: No interference between the pacemaker and the endoscopic capsule was observed. All the pacemakers functioned normally, and no increased incidence of adverse effects was observed. Neither was any pacemaker-induced interference observed on the capsule endoscopy images.

Organochlorine pesticides and PCBs in a southern Atlantic coastal lagoon watershed, Argentina.

There recently have been increasing interest in South America on organic pollutants from the coastal marine environment. This study intended to seek out the occurrence and distribution of persistent organochlorine compounds in the Mar Chiquita coastal lagoon watershed. The levels were measured in sediments and associated crabs. Though a significant number of PCBs (mainly penta- and hexachlorinated congeners) were detected, the concentrations were very low (in the order of ppbs), indicative of an estuarine environment with little industrial development. On the other hand, pesticide residues were higher than PCBs in one or two orders of magnitude, as a result of the important agricultural activities in the area. Heptachlor epoxide, DDT and its metabolites, and gamma-HCH were the predominant OC pesticides in sediments as well as in crabs. Significant differences among geographical areas: Channel 5 and Vivoratá Creek (northern and southern sampling sites, respectively) contained detectable pesticide concentrations (heptachlor epoxide, DDE, DDD, and mirex).

Micronucleus test in fish from a pampasic pond (Argentina): an estimation of the presence of genotoxic compounds.

The Los Padres pond is one of the commonly shallow, polymictic lakes from the so-called depressed Pampa (Argentina). Its watershed includes one affluent, named Los Padres creek, which flows through horticultural lands wherein great amounts of pesticides are applied. Opposite to this stream, the pond drains into La Tapera creek that is the effluent running toward the sea. Many studies have confirmed the capacity of various pesticides to induce genetic damage. The use of micronucleus (MN) tests in fish has enabled us to detect the presence of contaminants in the lakewater and to evaluate theirgenotoxic effects. For this purpose, water samples were collected during April, August, and December 1999 from both creeks characterized by different environmental conditions. In the laboratory, specimens oftetras Cheirodon interruptus (Pisces, Characidae) were reared in water samples from the two creeks. Control fish were kept in drinking water. Fifteen individuals from each experimental group were sacrificed after 24-, 48-, and 72-hour exposure intervals. Micronucleus frequency in fish erythrocytes was determined, and the Kruskal-Wallis test for statistic analysis was used. We made the following observations: (1) Highly significant differences occurred in MN frequency between the control group and the samples from both creeks. (2) An increase in MN frequency was evident in specimens sampled from the affluent input during the month of December. These results allowed us to conclude that the increase in MN frequency observed in fish belonging to both sampling sites would indicate the existence of genotoxic compounds in the Los Padres pond. The high MN frequency in fish collected near Los Padres creek inlet might be related to the polluted load transported by the affluent and discharged into the lake's surface waters. Future work would allow us to develop efficient methods for predicting the presence of genotoxic contaminants. It would be possible then to propose strategies for regulating and decreasing the sources of pollution that affect human health.

PCBs and organochlorines in tissues of silverside (Odontesthes bonariensis) from a coastal lagoon in Argentina.

A freshwater fish species, silverside (Odontesthes bonariensis) from Mar Chiquita coastal lagoon, Argentina, was analyzed for concentrations of several organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in liver, gonads, mesenteric fat and muscle, and the contents of the digestive tract over several stages of sexual maturation. PCBs and OCs were detected at ng/g concentrations (wet weight) in pooled samples, with levels generally in the order of fat > liver > gonad > muscle, reflecting the differences in tissue lipid content. Lipid-normalized concentrations of the analytes were relatively consistent among tissues, except for significantly higher concentrations of PCBs (e.g., 447.7 ng/g lipid wt) in the ovaries of female silverside. DDT and its metabolites, gamma-HCH, and several insecticides from the cyclodiene class, including endosulfan and endosulfan sulfate, were the predominant OCs in fish tissues and the contents of the digestive tract, reflecting recent and past pesticide use in this region. The ratio of OCs to PCBs in all tissues was >1; consistent with contamination of the region with OC pesticides. However, PCBs were dominated by penta- and hexachlorobiphenyls, which is consistent with direct (i.e. , nonatmospheric) inputs. Biomagnification of penta- and hexachlorobiphenyl PCB congeners was noted in fish tissues relative to the contents of the digestive tract. Total OC and PCB concentrations in the ovaries and muscle of silverside were below concentrations associated with reproductive impairment in fish or the limits for human consumption, respectively.

Genotoxic evaluation of the pyrethroid lambda-cyhalothrin using the micronucleus test in erythrocytes of the fish Cheirodon interruptus interruptus.

In order to develop experimental models able to detect genotoxic effects of pollutants in aquatic organisms, the genotoxicity of the pyrethroid lambda-cyhalothrin was studied using the micronucleus test in erythrocytes of Cheirodon interruptus interruptus. The frequency of micronuclei was examined in blood smears obtained from fishes exposed in vivo to three different concentrations (0.05; 0. 01; 0.001 ug/l) of the compound and sacrificed at nine sampling times (24, 48, 72, 96 h and 8, 12, 15, 19 and 23 days). As a positive control fishes were exposed to 5 mg/l of cyclophosphamide. Results obtained demonstrated the genotoxic effects of the pyrethroid in the experimental model employed. The variation in the micronuclei frequencies in the different sampling times could be related to the blood cell kinetics and the erythrocyte replacement. The results could be considered as a validation of the MN test in fishes for the assessment of genotoxic pollutants.

[Clinical findings in a lamb with congenital multiple abnormalities]. / Klinische Befunde bei einem Schaflamm mit angeborener multipler Missbildung.

A case of multiple, congenital malformations, with special emphasis on cardiac malformations (atrial- and ventricle septum defect, Ductus Botalli persistens, bilateral ventricle and atrial dilatation) in a lamb are described. Clinical findings, X-ray, ultrasound examination, electrocardio- and phonocardiogram, as well as pathology are discussed.

Cadmium, zinc and total mercury levels in the tissues of several fish species from La Plata river estuary, Argentina.

A survey of the concentrations of heavy metals - cadmium, zinc and total mercury - in the tissues of fifteen fish species from Samborombón Bay, La Plata river estuary, in Argentina, has been carried out. Liver appeared to be the main organ accumulating cadmium and zinc, while both liver and muscle showed a similar ability for accumulating mercury. The bioaccumulation process was verified for the three metals analyzed, even though low concentrations have been determined. The biomagnification process of the metals studied was not verified in this environment. The highest metal concentrations were recorded in Mugil liza, and particulate matter and sediments - which are closely related to its trophic and ecological habits - seemed to be the main source of metals for this species. Both Micropogonias furnieri and Mugil liza were recognized as possible indicator species for future monitoring programmes for heavy metals in Samborombón Bay. Considering the present results, this area of La Plata river estuary is characterized as a non-polluted environment.

Fatty acid metabolism in the calanoid copepod Paracalanus parvus: 1. Polyunsaturated fatty acids.

The metabolic fate of radioactive linoleate and alpha-linolenate administered to the South Atlantic copepod Paracalanus parvus was studied. The wild copepod was able to incorporate the labeled acids dissolved in seawater. The radioactive linoleate was elongated to 20:2omega6 and 22:2omega6 and desaturated by a delta6 desaturase to 18:3omega6. alpha-Linolenate was also desaturated by a delta6 desaturase to 18:4omega3 and elongated to 20:3omega3. The copepod was able to convert alpha-18:3 to 20:5omega3 and 22:6omega3.

Fatty acid metabolism of the calanoid copepod Paracalanus parvus: 2. Palmitate, stearate, oleate and acetate.

The de novo biosynthesis of fatty acids in the wild, calanoid copepod Paracalanus parvus was studied. The incubation of labeled acetate proved the de novo biosynthesis of saturated and monounsaturated even fatty acids from 14 to 20 carbons and the 22:1 acid. Saturated and monounsaturated uneven fatty acids from 15 to 21 carbons were also synthesized. The copepod could not synthesize linoleic and alpha-linolenic acids. By administration of [1-14C]palmitate, [1-14C]stearate and [1-14C]oleate, it was possible to elucidate the general pattern of the de novo biosynthesis of fatty acids in the wild P. parvus.

Lipid metabolism of the yellow clam, Mesodesma mactroides: 3-saturated fatty acids and acetate metabolism.

The fate of labeled palmitate, stearate, and acetate administered to the yellow clam, Mesodesma mactroides, was investigated. 1(-14)C palmitic and 1(-14)C stearic acids were oxidized to CO2 to a limited extent. They were mainly incorporated in diacylglycerols and triacylglycerols and were converted to higher homologs. After administration, palmitic acid was converted to stearic and oleic acids, whereas administered stearic acid was converted to 18:1, 18:2, 20:1, and 20:2 acids. Labeled acetate was readily included by the clam in 12:0, 14:0, 14:1, 15:0, 16:1, 16:1, 16:2, 18:2, 18:1, 18:2, 20:1, 20:2, and 20:3 acids.

Lipid metabolism of the yellow clam, Mesodesma mactroides: 2-polyunsaturated fatty acid metabolism.

The fate of labeled linoleic, alpha-linolenic, and higher homologs of alpha-linolenic acid administered to the yellow clam, Mesodesma mactroides, was investigated. It was found that the clam incorporated the acids dissolved in sea water and converted 18:2 (n-6) into 20:2 (n-6) and 18:3 (n-3) into 18:4 (n-3) and 20:3 (n-3). The addition of casein hydrolysate to the sea water increased the desaturation capacity of the calm and allowed the conversion of 18:2 (n-6) into 18:3 (n-6) to be demonstrated. An enhanced desaturation of 18:3 (n-3) into 18:4 (n-3) was also demonstrated. After 12 hr admininistration of the acid, no radioactivity was found in arachidonic, 20:5 (n-3), or 22:6 (n-3). Feeding the clams a culture of Phaeodactylun tricornutum previously incubated with 1-14C-alph-linolenic acid demonstrated that all the homologs of the alpha-linolenic series were found in the clam without any important changes. Six hour administration of labled linolenic acid resulted in the incorporation of the acid into diglycerides and phospholipids.

Lipid metabolism of the yellow clam, Mesodesma mactroides: I. Composition of the lipids.

The lipid composition of the yellow clam, Mesodesma mactroides, that lives in the northern beaches of the Buenos Aires province of Argentina was studied. The main nonpolar lipids are triglycerides and alkoxyglycerides. Phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl serine are the main phospholipids. The predominant fatty acids are 16:0, 16:1omega7, 18:0, 18:1omega9, 20:5omega3, and 22:6omega3. They are mainly provided by the clam's food and stored in the hepatopancreas. The content of polyunsaturated acids increases in summer together with an increase in nonpolar lipids and is correlative with an increase in phytoplankton in the sea water. Sexual maturity modifies the lipid composition of gametes.