Electroencephalographic biofeedback of SMR and beta for treatment of attention deficit disorders in a clinical setting

Six children were provided with long-term biofeedback and academic treatment for attention deficit disorders. Their symptoms were primarily specific learning disabilities, and, in some cases, there were varying degrees of hyperkinesis. The training consisted of two sessions per week for 10 to 27 months, with a gradual phase-out. Feedback was provided for either increasing 12-to 15-Hz SMR or 16- to 20-Hz beta activity. Inhibit circuits were employed for blocking the SMR or beta when either gross movement, excessive EMG, or theta (4–8 Hz) activity was present. Treatment also consisted of combining the biofeedback with academic training, including reading, arithmetic, and spatial tasks to improve their attention. All children increased SMR or beta and decreased slow EEG and EMG activity. Changes could be seen in their power spectra after training in terms of increased beta and decreased slow activity. All six children demonstrated considerable improvement in their schoolwork in terms of grades or achievement test scores. None of the children are currently on any medications for hyperkinetic behavior. The results indicate that EEG biofeedback training, if applied comprehensively, can be highly effective in helping to remediate children who are experiencing attention deficit disorders.The authors would like to thank Mr. Kevin Bianchini for his assistance in this study.     

The active site of the P99 beta-lactamase from Enterobacter cloacae.

Labelling the beta-lactamase of Enterobacter cloacae P99 with a poor substrate or a mechanism-based inactivator points to an active-site serine residue in a sequence closely resembling that of the ampC beta-lactamase. These results establish the P99 enzyme as a class-C beta-lactamase, and the concurrence of the two approaches helps to confirm the reliability of determining active-site sequences with the aid of mechanism-based inactivators.     

Echinodermes (Homalozoa: Cornuta et Mitrata) nouveaux pour l'Ordovicien du Massif Armoricain et conséquences paléogéographiques

Two specific genera of Bohemian Llanvirn(Sarka Formation), Reticulocarpos and Lagynocystis have been recognized in Traveusot, le Pissot and Pierre Melière Formations (Llanvirn and Llandeilo of the Armorican Massif). Though three species are new (R. pissotensis, R. sp., Lagynocystis sp.) this discovery once more underlines the relationships between Bohemia and Armorican Massif during this period.     

Biomass production in mass cultures of marine phytoplankton at varying temperatures

Natural populations of marine phytoplankton obtained from a large outdoor pond were grown on waste water-sea water mixtures in laboratory continuous cultures in the temperature range 5–33 °C. Virtually all of the influent inorganic nitrogen (14.0 mg l^?1) was assimilated at every temperature tested. There was, however, a distinct change in dominant species with temperature: below 19.8 °C Phaeodactylum tricornutum was dominant, at 27 °C Nilzschia sp. was the main species, and as the temperature increased above 27 °C a blue-green alga, Oscillatoria sp., became increasingly dominant. There is some indication that the excellent growth of P. tricornutum below 10 °C was related to a dramatic increase in the nutrient content per cell as the temperature decreased. Thus at low temperatures reduced division rates are compensated for by increased nutrient uptake rates. It follows that there is a transfer of phytoplankton protein from numerous small cells at intermediate temperatures to large cells that are reduced in numbers at lower temperatures but which represent the same total organic matter. The effect of this phenomenon on annual food chain efficiencies in both controlled and natural marine ecosystems is unknown.     

Local and spatially coordinated movements in Dictyostelium discoideum amoebae during chemotaxis

We have studied chemotaxis by individual Dictyostelium discoideum amoebae using strong, local gradients of the chemoattractant cyclic AMP. Gradients were provided by diffusion of cyclic AMP from a microneedle, which could be positioned at various points around the cell. Responses to changes in the gradient indicate how the cell is structurally organized for chemotactic movement. There is a polarity in the responsiveness of the surface to stimulation by cyclic AMP along the length of the amoeba. Furthermore, two aspects of chemotactic movement can be distinguished. The first response to cyclic AMP is a locally generated extension of a hyaline pseudopod from the region of the surface nearest the stimulus. The second response, the flow of cytoplasm in the direction of the stimulus, is coordinated and separate from the first response. The coordination appears to depend on the nucleus or on the microtubule-organizing center.     

Surface solar ultraviolet radiation for paleoatmospheric levels of oxygen and ozone

Many investigators have concluded that the level of solar ultraviolet radiation (200–300 nm) reaching the surface was a key parameter in the origin and evolution of life on Earth. The level of solar ultraviolet radiation between 200 and 300 nm is controlled primarily by molecular absorption by ozone, whose presence is trongly coupled to the level of molecular oxygen. In this paper, we present a series of calculations of the solar ultraviolet radiation reaching the surface for oxygen levels ranging from 10^–4 present atmospheric level to the present level. The solar spectrum between 200 and 300 mn has been divided into 34 spectral intervals. For each spectral interval, we have calculated the solar ultraviolet radiation reaching the Earth's surface by considering the attenuation of the incoming beam due to ozone and oxygen absorption. A one-dimensional photochemical model of the atmosphere was used for these calculations.     

Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.     

Amino acid sequence around the thiol and reactive acyl groups of human complement component C4.

Activation of the fourth component of complement (C4) by C1s results in the generation of a reactive acyl group, able to react with putrescine, and in the release of a free thiol group that cannot be detected in the native haemolytically active molecule. Both the reactive acyl group and the free thiol group have been shown to reside in C4d, a fragment of the alpha'-chain of C4b derived from digestion of the molecule with the control proteins C3b inactivator and C4-binding protein. Peptides derived from CNBr digestion of [1,4-14C]putrescine-labelled and iodo(2-14C]acetic acid-labelled C4d have been obtained and used to establish a continuous sequence of 88 residues from the N-terminus of the molecule. The thiol and reactive acyl groups are contained in an octapeptide that shows near identity with the equivalent sequences reported for alpha 2-macroglobulin and C3. Other adjacent short sections also show homology of sequence between the three proteins, and it is highly likely that they contribute to the overall structure that gives a unique reactivity to the thiol ester bond postulated to exist in the native forms of the three proteins.     

Valine-sensitive acetohydroxy acid synthases in Escherichia coli K-12: unique regulation modulated by multiple genetic sites.

Summary Spontaneous mutants (146) of Escherichia coli K-12 were selected that were resistant to inhibition of growth by 1.2 mM L-valine (Val^r). The Val^r isolates, containing acetohydroxy acid synthase resistant to feedback inhibition by L-valine (AHAS^r), were classed according to cotransduction of the mutation with leu. Several mutations resulting in an AHAS^r phenotype were found to be cotransducible with glyA. However, no mutations causing a Val^r phenotype were linked to ilv. AHAS activity was more closely examined in representatives of three classes of mutants with Val^r linked to leu, labeled ilv-660, ilv-661, and ilv-662. The ilvE503 allele in E. coli K-12, known to cause a two- to three-fold derepression of AHAS, was found to affect regulation of synthesis of both valine-sensitive AHAS (AHAS^s) and AHAS^r in the mutants containing ilv-660 and ilv-661, whereas it affected repression of AHAS^s, only, in the mutant containing ilv-662. Further, both AHAS^s and AHAS^r in the ilv-661 mutant were repressed by valine, whereas valine did not repress AHAS^r synthesis in the strain carrying ilv-660 and only partially repressed AHAS^r in the strain carrying ilv-662. Unexpectedly, AHAS^r synthesis in strains carrying ilv-660 or ilv-662 was repressible by leucine. The ilv-660 locus appears to be similar in position to ilvH and encodes a product that confers valine-sensitivity upon AHAS activity in the wild-type E. coli K-12. The ilv-660 and ilv-662 loci may normally encode products that influence both the feedback sensitivity of AHAS and control of AHAS biosynthesis.