Pesticide residues in boreal arable soils: Countrywide study of occurrence and risks.

Large volumes of pesticides are applied every year to support agricultural production. The intensive use of pesticides affects soil quality and health, but soil surveys on pesticide residues are scarce, especially for northern Europe. We investigated the occurrence of 198 pesticide residues, including both banned and currently used substances in 148 field sites in Finland. Results highlight that pesticide residues are common in the agricultural soils of Finland. A least one residue was found in 82% of the soils, and of those 32% contained five or more residues. Maximum total residue concentration among the conventionally farmed soils was 3043 µg/kg, of which AMPA and glyphosate contributed the most. Pesticide residues were also found from organically farmed soils, although at 75-90% lower concentrations than in the conventionally farmed fields. Thus, despite the application rates of pesticides in Finland being generally much lower than in most parts of central and southern Europe, the total residue concentrations in the soils occurred at similar or at higher levels. We also established that AMPA and glyphosate residues in soil are significantly higher in fields with cereal dominated rotations than in grass dominated or cereal-grass rotations. However, risk analyses for individual substances indicated low ecological risk for most of the fields. Furthermore, the total ecological risk associated with the mixtures of residues was mostly low except for 21% of cereal dominated fields with medium risk. The results showed that the presence of mixtures of pesticide residues in soils is a rule rather than an exception also in boreal soils. In highly chemicalized modern agriculture, the follow-up of the residues of currently used pesticides in national and international soil monitoring programs is imperative to maintain soil quality and support sustainable environment policies.

Assessing toxicity of metal contaminated soil from glassworks sites with a battery of biotests.

The present study addresses toxicological properties of metal contaminated soils, using glassworks sites in south-eastern Sweden as study objects. Soil from five selected glassworks sites as well as from nearby reference areas were analysed for total and water-soluble metal concentrations and general geochemical parameters. A battery of biotests was then applied to assess the toxicity of the glassworks soil environments: a test of phytotoxicity with garden cress (Lepidium sativum); the BioTox™ test for toxicity to bacteria using Vibrio fischeri; and analyses of abundancies and biomass of nematodes and enchytraeids. The glassworks- and reference areas were comparable with respect to pH and the content of organic matter and nutrients (C, N, P), but total metal concentrations (Pb, As, Ba, Cd and Zn) were significantly higher at the former sites. Higher metal concentrations in the water-soluble fraction were also observed, even though these concentrations were low compared to the total ones. Nevertheless, toxicity of the glassworks soils was not detected by the two ex situ tests; inhibition of light emission by V. fischeri could not be seen, nor was an effect seen on the growth of L. sativum. A decrease in enchytraeid and nematode abundance and biomass was, however, observed for the landfill soils as compared to reference soils, implying in situ toxicity to soil-inhabiting organisms. The confirmation of in situ bioavailability and negative effects motivates additional studies of the risk posed to humans of the glassworks villages.

Cultivating the cortex in German neuroanatomy.

The cerebral localization of mental functions is one of the centerpieces of modern brain research. Though the localization paradigm in its cultural and social interwovenness has been characterized as successful in the last third of the nineteenth century by a variety of historians of the neurosciences, there is also general agreement that localization came under threat around 1900. Besides the so-called holistic protest against the localization of mental functions, the neuroanatomical approach itself was challenged by experimental psychology, psychiatric nosology, and psychoanalysis. This story underestimates the fact that anatomically-based localization remained powerful in response to these multiple challenges. This meant a neuroanatomical revision of tools, concepts, and practices. But this meant also a shift in the cultivation of the cortex from a more philosophical agenda to rather concrete political claims. More specifically, the idea of the cortext as the noblest part of man was supplemented by suggestions concerning its "Höherzüchtung." I will analyze this re-orientation and radicalization in two steps. First, I briefly discuss the anatomical and philosophical account of Theodor Meynert and then turn to Paul Flechsig who in the late nineteenth century inscribed the ability to create culture and civilization into the cortext. Second, I focus on the neuroanatomists Oskar and Cécile Vogt, who began their careers around 1900 and expanded the cultivation of the cortext. Even before World War I, they proclaimed a "cerebral hygiene." Consequently, the Vogts linked their innovative neuroanatomical researches with the rising field of genetics, racial hygiene, and eugenics. In the early Weimar Republic, the Vogts openly supported socialist ideas and were engaged in establishing an Institute for Brain Research in Soviet Moscow, where Lenin's brain was analyzed. By the end of the Weimar Republic, the rhetoric of the Vogts was bluntly authoritarian. Based on a few anatomical examinations of so-called elite brains and the brains of criminals, they made concrete suggestions for eugenics and the breeding of "one-sidedly gifted leaders." Given the remarkable popularity of the Vogts around 1930, their program is an important example of the hubris of predicting and guiding future developments on the basis of scientific authority. It can be regarded as an ironic nemesis that the Vogts - never sympathizing with the political aims of the National Socialists - were forced to finish their careers as influential Kaiser Wilhelm scientists in Nazi-Germany.

Prolegomena to a history of radical brains in the nineteenth century: physiognomics, phrenology, brain anatomy.

This paper deals with the coming into being of skulls and brains of geniuses as objects of scientific investigation. Late-eighteenth-century physiognomics and physical anthropology established parameters for explaining intellectual differences among human beings. These were refined and modified by phrenology. Although phrenology was contested, its methods for investigating the brains of geniuses presaged the beginnings of modern elite brain research in the 1850's. In this decade, the older interest in brains and skulls of geniuses, which was part of the hagiography of celebrated persons, was transformed into a systematic and comparative exploration of radical brains.

On the history of deformation phosphenes and the idea of internal light generated in the eye for the purpose of vision.

Deformation phosphenes are light sensations evoked by deformation of the eyeball in total darkness. They were first reported in Western literature by Alcmaeon of Croton in the fifth century B.C. The phenomenon of deformation phosphenes was instrumental in prompting some pre-Socratic philosophers and Plato to conceive the idea that efferent light is emitted from the eye for the purpose of vision and a 'cone of vision' is formed by interaction with the external light. In the theories of vision this cone of vision played an important role as a signal-transmitting structure and was also used by the Greek opticians as a geometrical construction to explain optical properties of vision. The impact of the deformation phosphene experiment on the ideas of visual sensation can be followed from Greek antiquity through the period of Roman dominance and Galen's medical teaching on to medieval times and up to the late Renaissance when, based on the anatomy of the eye as illustrated by Felix Platter, the image formation on the retina was correctly described for the first time by Johannes Kepler. In the generations following, deformation phosphenes were still employed as an important argument in defence of the theories of vision. However, the idea of physical light generated by eyeball deformation was rejected with increasing frequency during the 17th and 18th centuries. The literature on this topic is discussed, comprising the contributions of the Arabic philosophers and physicians of the 9th and 10th centuries A.D., the Franciscan and Dominican philosophers of the 13th century, Nicolaus Cusanus of the 15th century, several anatomists of the 16th and 17th centuries, Kepler, Plempius, Descartes, Boyle, Newton and others. After Kepler, the mechanical interpretation of the deformation phosphene being caused by direct action of the eyeball deformation onto the retina slowly became dominant, and the idea that physical light is generated in the eye disappeared. The experimentum crucis in this matter was performed by Giovanni Battista Morgagni (1682-1771) and repeated and extended by Georg August Langguth (1711-1782). On the basis of their results, the case for physical light being generated in the eye by deformation was refuted definitively and slowly vanished thereafter from scientific literature. Deformation phosphenes were used in the 19th and 20th centuries as an instructive example of the percepts evoked by inadequate stimulation of a sense organ. J.E. Purkyne in particular contributed to the study of deformation phosphenes, and finally in 1978, F. Tyler devoted a careful study to the differences between monocular and binocular deformation phosphenes.(ABSTRACT TRUNCATED AT 400 WORDS)

[Development of the Cartesian "Mechanics of vision" and its limits]. / Die Entfaltung der cartesischen "Mechanik des Sehens" und ihre Grenzen.

In his "Objections and Replies" to the "Meditations" Descartes developed a concept of sensory perception as a three-stage mechanism. Firstly, it consists of a purely mechanical process which comprises an excitation of the sensory organs leading to motion in the nerves. Secondly, he understood perception as a psychophysical interaction in which a specific signal pattern representing the surroundings is presented to the soul. Finally, in stage three, classification and judgement of the object presented complete the perceptual process. Ernst Cassirer suggests that Descartes' conception of the soul is elucidated more precisely in his physiological writings, in which physiology is considered as a field for the application of philosophical analysis. In the present paper an attempt is made to demonstrate that Descartes' mechanistic concept of vision led to a definition of perception as a active process within the soul. Based on Kepler's theory of the inverted retinal image and a rejection of the traditional idea of light generated within the eye, Descartes arrived at the hypothesis that one must strictly differentiate between the object image and its perceptual correlate. Since the objective physical conditions do not suffice for a complete understanding of perception, a restricted validity of the mechanistic theory of vision is the consequence. Thus Descartes transposed the question of perception as an active process from neurophysiology to psychology and established its relevance within his own metaphysics, hereby laying the foundations for a psychological discussion of theories of vision in British Sensism.

The effect of dark adaptation on the responses of cat retinal ganglion cells to eyeball deformation.

Eyeball deformation in total darkness leads to an activation of on-center ganglion cells and an inhibition of off-center ganglion cells. After "deformation off" most on-center ganglion cell activity decreased slowly to the normal spontaneous dark level, while in off-center ganglion cells some returned according to an exponential function to normal dark activity, while others had a transient postinhibitory activation period. In general, the response type of latency class I and latency class II neurons was the same. Dark adaptation of 30-45 min duration only changed this neuronal response pattern slightly, if at all. A detailed statistical analysis is provided for the four classes of retinal ganglion cells recorded: latency class I on-center and off-center neurons and latency class II on-center and off-center neurons. The missing effects of dark adaptation on neuronal responses evoked by eyeball deformation are explained by three possible models. The more plausible one assumes that horizontal cells are depolarized by retinal stretch. Their interaction with cone on-bipolars or cone off-bipolars is fairly independent of photoreceptor adaptation or transmitter release at the cone pedicles and is still effective when all molecular receptor sites at cone/bipolar cell synapses are occupied during scotopic states of dark adaptation. In psychophysical experiments (two subjects), as in the neuronal responses, we also could not find any indication that the "pressure phosphenes" evoked by lateral eyeball indentation are altered during dark adaptation.

Purkyne's description of pressure phosphenes and modern neurophysiological studies on the generation of phosphenes by eyeball deformation.

(a) When a subject indents one of his eyeballs in total darkness, he immediately perceives light extending slowly across the whole visual field of the indented eye. The appearance and the time course of these pressure or deformation phosphenes are described. (b) With simultaneous binocular indentation of the eyeballs a flickering patterned phosphene is observed. (c) A short history of the research on pressure phosphenes and its consequences for the theories of vision is presented. (d) Purkyne's observations of monocular deformation phosphenes are described. He repeatedly noted patterned light structures, which most observers only perceive with simultaneous binocular eyeball deformation. It is suggested that Purkyne's deviating observations were caused by amblyopia of one eye. (e) The neurophysiological basis of the monocular pressure phosphenes was investigated by means of microelectrode recordings from single optic tract fibers. The activity of single retinal ganglion cells (on-center, off-center neurons, latency class I [Y-neurons] or latency class II [X-neurons]), was recorded in anaesthetized cats. Eyeball deformation in total darkness led to an activation of the on-center ganglion cells, while the off-center ganglion cells were inhibited. The latency and strength of this activation or inhibition varied considerably between different neurons, but were fairly constant in the same neuron when the eyeball indentation was repeated after a pause of 1-3 min. The latency and strength of neuronal activation or inhibition seemed to be dependent mainly upon the neuron location relative to the point of eyeball indentation. Some on-center neurons also exhibited a short activation at "deformation off". (f) The antagonistic response type of on-center and off-center ganglion cells was also observed when the eyeball was deformed as a hydrostatic open system and the intraocular pressure was kept at 25 mm Hg basic pressure. (g) Dark adaptation up to 45 min affected the deformation responses of retinal neurons only to a small degree, if at all. This corresponds to the observation that deformation phosphenes in a human observer changed little during the course of dark adaptation. (h) We assume that the activation of on-center and inhibition of off-center ganglion cells by eyeball deformation are caused by retinal stretching, which also leads to horizontal cell stretch. Stretching the horizontal cell membrane probably generates an increase in membrane sodium conductivity and a depolarization of the membrane potential. This depolarization of the horizontal cell membrane potential is transmitted either directly or indirectly (via receptor synapses) from the horizontal to the bipolar cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Double trisomy as a mosaic. Case history (48, XYY, + 21/47,XY, +21) and survey of the literature of mixed autosomal-gonosomal trisomies.

The case of a boy is reported showing the typical symptoms of Down's syndrome, in whom the chromosome analysis revealed a mosaic karyotype: 50% 48,XYY,+21/50% 47,XY,+21. Findings of 92 cases from the literature are summarized to show the frequencies of double gonosome-autosome aneuploidies compared with single trisomies. Referring to the different chromosomes involved, the aneuploid cell formation, the frequencies of combinations, as well as the tendency to mosaic formation are analyzed. The age of parents at the time of birth and the life expectancy are described as well as the clinical symptoms. Theories concerning the origin of double aneuploidies are discussed.