A microdrive positioning adapter for chronic single unit recording

A new micropositioner design for use in chronic, transdural single unit recording studies is presented. The adapter is used to position an electrode microdrive assembly to any desired location within a surgically implanted recording chamber. The adapter uses a radial positioning technique that requires few moving parts. In comparison with the X-Y slide manipulator it replaces, it is more durable, it provides access to a larger brain area, and it attaches more securely. In addition, provision can be made to mount a second microdrive, permitting two electrodes to be manipulated independently.     

Subcutaneous immunization of rabbits with nitrocellulose paper strips impregnated with microgram quantities of protein

The desire to produce specific antibodies to substances available only in minute quantities and increased concern for laboratory animal welfare have each contributed to heightened interest in alternative immunization methods. In this report, we describe the production of polyclonal antibodies against microgram quantities of a weakly immunogenic tumor-associated protein of canine origin. Our technique employs the subcutaneous implantation of nitrocellulose electroblot strips without the use of adjuvant. The method is simple, appears reliable, can be used to improve antigen purity, and is applicable for either polyclonal or monoclonal antibody production in different host species. In addition, because traditional adjuvants are not required with this system, severe inflammatory responses and associated animal discomfort are reduced.     

A nonredundant role for the adapter protein Shc in thymic T cell development

Signaling via the pre-T cell receptor (pre-TCR) regulates survival, proliferation, allelic exclusion and differentiation of thymocytes. The role played by the adapter protein Shc in T cells has remained controversial, and its role in pre-TCR signaling has not been addressed. We examined Shc function in thymic T cell development using two genetic approaches. Cre-loxP-mediated inducible expression in transgenic mice of a phosphorylation-defective mutant of Shc impaired signaling through the pre-TCR as well as subsequent proliferation and differentiation. Conditional deletion of the Shc locus in thymocytes also affected thymic maturation at the same pre-TCR developmental stage. Thus, both Shc expression and its tyrosine phosphorylation play an essential and nonredundant role in thymic T cell development.     

A portable diffuse reflectance spectrophotometer for the rapid and automatic measurement of meat pigments

A portable reflectance spectrophotometry system, which can measure a wide range of absorbance and has an adhesive pad type fibre optic probe, was developed to improve the availability of non-invasive reflectance spectrophotometry. A Czerny-Turner type spectrometer, which can be connected to an optical fibre probe, was developed, and a linear charge coupled device (CCD) was used as its light detector to increase data acquisition speed. The scanning time of the linear CCD is automatically controlled in accordance with the reflectance of meat to increase the dynamic range of absorption. We tried to apply this instrument to samples of meat pigments in order to demonstrate whether reflectance spectrophotometry is suitable for evaluating the freshness of meat. We examined the myoglobin solution in the form of the met-derivative in order to detect the concentration of myoglobin. The absorbance spectrum of myoglobin in the range of 0-4 mg dl(-1) was successfully distinguished with this instrument.     

A portable scanning reflectance spectrophotometer using visible wavelengths for the rapid measurement of skin pigments

A portable rapid scan reflectance spectrometer (400-700 nm in 2.8 s) has been developed for the measurement of cutaneous pigments. The instrument incorporates a tungsten halogen lamp light source, light transmission by fibre optics and wavelength selection by a circular variable wavelength interference filter. A microcomputer controls the instrument and processes the data. The performance of the instrument was evaluated by undertaking in vitro measurements of the reflectance spectra of blood. An index of the haemoglobin content of the sample based on the gradients of the log inverse reflectance spectrum between isobestic points at 527.5, 544 and 573 nm was devised and shown to be independent of the oxygenation of the haemoglobin. The haemoglobin index was combined with measurements at 558.5 nm, a wavelength at which absorbance is sensitive to the oxygenation of haemoglobin, to give a measure of oxygen saturation. The parameter was validated by determining the oxygen dissociation curve of red cells in plasma in vitro at pH 7.33, 37 degrees C and under a partial pressure of 40 mmHg of CO2.     

A GTP-binding adapter protein couples TRAIL receptors to apoptosis-inducing proteins

Apoptosis-inducing tumor necrosis factor (TNF) family receptors recruit the proforms of caspase family cell death proteases to ligand-receptor complexes through interactions with intracellular adapter proteins. We have found that the GTP-binding protein DAP3 binds directly (with high affinity) to the death domain of TNF-related apoptosis-inducing ligand (TRAIL) receptors, and is required for TRAIL-induced apoptosis. DAP3 also associates with the pro-caspase-8--binding adapter protein Fas-associated death domain (FADD), and links FADD to the TRAIL receptors DR4 and DR5. We have also found that binding of DAP3 to FADD and activation of pro-caspase-8 in an in vitro reconstituted system is GTP-dependent. Elucidation of this mechanism suggests GTP-binding proteins as potential targets for pharmacological intervention in TRAIL-induced apoptosis.