Comparative toxicities of fungicide and herbicide formulations on freshwater and marine species.

The estimation of the toxic effects of plant protection products on non-target aquatic organisms is essential for risk assessment evaluation. In this study the acute toxicity of two fungicide and two herbicide formulations was determined in four marine species in comparison with the toxicity assessed for the freshwater crustacean Daphnia magna. From the study it is indicated that the marine crustacean species are effectively protected when acute toxicity data on Daphnia magna are used as surrogate for risk assessment while the comparative sensitivity of the unicellular green algae may vary considerably, depending on the mode of action of the specific formulation.

Cerebellar granule cell differentiation in mutant and X-irradiated rodents revealed by the neural adhesion molecule TAG-1.

In the external granular layer of the cerebellum, the granule cell precursors express the transient axonal glycoprotein TAG-1, a molecule involved in adhesion and neurite outgrowth. Granule cells express TAG-1 transiently, just as they extend neurites before migrating over the radial glia. The present study aims to investigate whether the expression pattern of TAG-1 is altered when granule cells develop abnormally. We studied in vivo models in which Purkinje and/or granule cell defects occur during postnatal development. These include the cerebellar mutant mice staggerer and lurcher as well as rats irradiated during postnatal development. Neither alterations in Purkinje cell differentiation nor the related granule cell loss in the mouse mutants impairs the ability of the surviving granule cell precursors to express TAG-1. Also, early granule cell loss in the X-irradiated rats do not disturb the TAG-1 expression phase in the patches of surviving granule cell precursors. Ectopic granule cells found in the adult cerebellum of X-irradiated rats do not bear the molecule, although they are located in the most superficial part of the molecular layer, occupied by the immunopositive cells a few days earlier. Thus, TAG-1 marks a very precise stage of granule cell differentiation, and the inward migration process itself is not required for the cessation of the expression. We postulate that TAG-1 may be involved in local differentiation steps restricted to the deep external granular layer such as parallel migratory routes or synchrony of axonal growth.

Expression of the cell adhesion proteins BEN/SC1/DM-GRASP and TAG-1 defines early steps of axonogenesis in the human spinal cord.

We have studied the expression pattern of two cell adhesion proteins of the immunoglobin (Ig) superfamily, BEN/SC1/DM-GRASP (BEN) and the transient axonal glycoprotein TAG-1, during the development of the human nervous system. This study was performed by immunocytochemistry on sections of human embryos ranging from 4 to 13 weeks postconception. The overall distribution of the two proteins during development is very similar to that reported in other vertebrate species, but several important differences have been observed. Both proteins exhibit a transient expression on selected neuronal populations, which include the motor and the sensory neurons. In addition, BEN was also detected on virtually all neurons derived from the neural crest as well as in nonneuronal tissues. A major difference of expression with the chick embryo is that, in the motor neurons, BEN expression was not observed at early stages of development, thus arguing against a role of this molecule in pathfinding and fasciculation. BEN was observed to be restricted to subsets of motor neurons, such as the medial column at the upper limb level. Expression was also detected in a laterodorsal population of the ventral horn cells, which are likely to correspond to migrating preganglionic neurons that originate from the motor pool at the thoracic level. TAG-1 was found on commissural neurons and weakly on the sympathetic neurons; it was also detected on restricted nonneuronal populations. In addition, we observed TAG-1 expression in fibers that could correspond either to subsets of dorsal root ganglia (DRGs) central afferences (including the Ia fibers) or to the axons of association interneurons and in scattered motoneurons likely to correspond either to preganglionic neurons, to gamma-motoneurons, or to late-born motoneurons. Therefore, our results indicate that the molecular strategies used to establish the axonal scaffolding of the nervous system in humans are extremely conserved among the different vertebrates.

The role of Doppler Perfusion Index as screening test in the characterization of focal liver lesions.

PURPOSE: Doppler Perfusion Index (DPI) has been used in the detection of overt liver metastatic disease. In the present prospective study we evaluated the use of DPI in the differential diagnosis of liver tumours. MATERIALS AND METHODS: We have included in our study 76 patients with focal hepatic lesion and 39 subjects as control group. All patients were evaluated by Color Doppler Ultrasound, and/or Spiral Computerised Tomography, Magnetic Resonance Imaging and biopsy. The radiologist performed DPI measurements was blind from the final diagnosis of the other methods. RESULTS: DPI measurements in the control group ranged from 0.07 to 0.22 (mean value 0.14), in 42 cases with benign lesions (group A) ranged from 0.05 to 0.53 (mean 0.15) and in 34 cases with malignant lesions (group B) ranged from 0.39 to 0.75 (mean 0.53). There was a statistically significant difference in DPI measurements between the control group and group B. CONCLUSIONS: Our results suggest that the DPI may differentiate malignant from benign focal hepatic lesions and therefore can be used as a screening test in the routine clinical practice.

Comparative toxicity of the phytotoxins (8R,16R)-(-)-pyrenophorin and (5S,8R,13S,16R)-(-)-pyrenophorol on aquatic organisms.

The acute toxicities of the fungal phytotoxins (8R,16R)-(-)-pyrenophorin and (5S,8R,13S,16R)-(-)-pyrenophorol on Vibrio fischeri, Oscillatoria perornata, Pseudokirchneriella subcapitata, Lemna minor and Artemia fransiscana were evaluated. (8R,16R)-(-)-pyrenophorin was more toxic than (5S,8R,13S,16R)-(-)-pyrenophorol to V. fischeri, O. perornata, L. minor and A. fransiscana. The highest acute toxicity of (8R,16R)-(-)-pyrenophorin was exhibited on V. fischeri (5 min median effective concentration of 3.57 M 10(-5)) whereas the corresponding value for (5S,8R,13S,16R)-(-)-pyrenophorol was 801 M 10(-5). P. subcapitata exhibited a lack of sensitivity (median inhibitory concentration of >10 M 10(-5)) to both phytotoxins.

Multiple influences on the migration of precerebellar neurons in the caudal medulla.

Neurons destined to form several precerebellar nuclei are generated in the dorsal neuroepithelium (rhombic lip) of caudal hindbrain. They form two ventrally directed migratory streams, which behave differently. While neurons in the superficial migration migrate in a subpial position and cross the midline to settle into the contralateral hindbrain, neurons in the olivary migration travel deeper in the parenchyma and stop ipsilaterally against the floor plate. In the present study, we compared the behavior of the two neuronal populations in an organotypic culture system that preserves several aspects of their in vivo environment. Both migrations occurred in mouse hindbrain explants dissected at E11.5 even when the floor plate was ablated at the onset of the culture period, indicating that they could rely on dorsoventral cues already distributed in the neural tube. Nevertheless, the local constraints necessary for the superficial migration were more specific than for the olivary migration. Distinct chemoattractive and chemorespulsive signal were found to operate on the migrations. The floor plate exhibited a strong chemoattractive influence on both migrations, which deviated from their normal path in the direction of ectopic floor plate fragments. It was also found to produce a short-range stop signal and to induce inferior olive aggregation. The ventral neural tube was also found to inhibit or slow down the migration of olivary neurons. Interestingly, while ectopic sources of netrin were found to influence both migrations, this effect was locally modulated and affected differentially the successive phases of migration. Consistent with this observation, while neurons in the superficial migration expressed the Dcc-netrin receptor, the migrating olivary neurons did not express Dcc before they reached the midline. Our observations provide a clearer picture of the hierarchy of environmental cues that influence the morphogenesis of these precerebellar nuclei.

Mammographic findings following reduction mammoplasty.

Breast reduction mammoplasty is becoming an increasingly common procedure. A baseline mammogram is recommended after 35 years of age as the most effective method for detection of small breast cancers. A prospective study was conducted for the evaluation of the mammographic findings after reduction mammoplasty. During the last 7 years, 113 patients over 35 years of age underwent bilateral reduction mammoplasty. All patients had a preoperative mammogram. A new mammogram was obtained at 6 and 18 months after the procedure. All films were reviewed by the same two radiologists. Breast reduction was performed with the vertical bipedicle flap technique (McKissock) and the inferior pedicle technique. There were no apparent differences in the findings between the two methods. Most common findings were parenchymal redistribution in 102 (90.2%) and elevation of the nipple in 96 (84.9%), produced by a shift of the breast tissue to a lower position. Calcifications were seen in 29 (25.6%), and "oil cysts" in 22 (19.4%), caused by localized fat necrosis. A retroareolar fibrotic band was found in 23 (20.3%), from the transposed flap. Areolar thickening was observed in six (5.3%), and skin thickening in only two (1.7%), from scar tissue. Mammographic findings after reduction mammoplasty are predictable, thus preventing unnecessary biopsies and making the diagnosis of lesions unrelated to the procedure easier. All patients over 35 years of age should have a preoperative and a postoperative mammogram for future reference.

Improved characterisation of focal liver tumours: dynamic power Doppler imaging using NC100100 echo-enhancer.

OBJECTIVE: To assess the vascularisation of focal hepatic tumours using NC100100, enhanced power Doppler imaging. METHODS: Twenty-two patients with focal liver tumours (12 metastases and ten hemangiomas) were studied. Using standardised settings, power Doppler imaging with ATL HDI3000 was performed before and after intravenous administration of NC100100 contrast agent. The video-recorded examinations were digitised for off-line analysis on a personal computer. Regions of interest were defined over the entire tumour and a neighbouring area of the normal liver parenchyma. The temporal changes of the mean power Doppler signal intensity (PDSI) was quantified to provide contrast agent wash-in (PDSI-time) curves for the initial 40 s. RESULTS: Liver metastases were characterised by a rapid increase in PDSI, while the PDSI-time curves within hemangiomas were flat. The PDSI within the tumour increased significantly in ten subjects with liver metastases and only one subject with hemangioma. An enhanced rim around hemangiomas was seen in four subjects. There was no clear relationship between the contrast agent dose and the peak PDSI within metastases. CONCLUSIONS: Power Doppler imaging with NC100100 contrast agent enhances tumour visualisation and may aid differential diagnosis of focal liver lesions.