Identification of monoclonal antibodies specific for the T cell receptor complex by Fc receptor-mediated CTL lysis

Monoclonal antibodies (mAb) directed at the T cell receptor complex (TcR) on cloned T cells have generally been identified by their ability to inhibit the clone's antigen-specific function. Because such inhibition is highly dependent on antibody concentration and affinity, detection of anti-clonotypic antibodies to murine alloreactive T cells has been very difficult. In this report, an alternative method is described on the basis of the ability of antibodies specific for the TcR complex to activate T cells in an antigen-independent manner. The assay is based upon the observation that soluble antibodies to human T3 promote lysis of irrelevant, Fc receptor-positive targets by a human CTL line. By using this approach, an anti-TcR mAb has been identified among a panel of murine mAb generated against an alloreactive CTL clone. Induction of lysis by soluble anti-TcR mAb has been shown to require both the expression of Fc receptors on the target cell and conjugate formation between the effector and the target cell. This assay provides a screening procedure that is much more sensitive than inhibition of function, and it preferentially detects antibodies specific for cell surface molecules involved in T cell activation.     

Effect of nitrogen form on the growth and nitrate concentration of lettuce

Summary A pot experiment with lettuce involving three N forms each at six application levels, showed that lettuce can be grown satisfactorily with a very low nitrate content when supplied with ammonium sulphate and a nitrification inhibitor. For plants growing on nitrate N, the optimum midrib sap nitrate concentration as maturity approached was about 1400 mg/1 NO₃-N. Large losses of mineral N were observed from the peat medium, even in the absence of plants. A relationship is presented which would enable a lettuce grower to estimate whole-shoot nitrate concentration from a quick test of midrib sapi.e. NO₃-N (mg/kg in fresh shoot) =0.14×NO₃-N (mg/l in sap). Tipburn was worst at intermediate levels of applied N, and was less serious with pure ammonium nutrition than with nitrate.     

Stereometry in very close-range stereophotogrammetry with non-metric cameras for human movement analysis

In this paper a stereophotogrammetric algorithm based on a black-box approach to the modelling of object to image spaces relationship is proposed. The algorithm is well suited for 'very close-range photogrammetry', with respect to experiments in which the measurement field is 0.5 X 0.5 X 0.5 m or smaller, as in the analysis of a few or small body segments movements. The attainable accuracy is high, better than 0.1% of the observation distance. Non-professional and even different cameras can be used. Consequently an inexpensive experimental set-up can be realized. A very simple, cheap and easily usable calibration object is needed. Computation time for the reconstruction of object-space co-ordinates of point body landmarks is one order of magnitude lower than in the case of the Direct Linear Transformation (DLT) (Abdel Aziz and Karara, Proceedings of the ASP/U1 Symposium on Close-Range Photogrammetry, pp. 1-18. American Society of Photogrammetry, 1971; Marzan and Karara, Proceedings of the Symposium on close-range Photogrammetric Systems, pp. 420-467. American Society of Photogrammetry, 1975). Computation time for calibration is two-fold in respect of the DLT. An example of application to the recording of the movements of the index finger with respect to the metacarpophalangeal joint is given.     

On the population dynamics and ecology of the shrimp species (Crustacea,Decapoda, Natantia) in the Central Amazonian river Tarumã-Mirim

Summary Collections over four years in the habitat of submerged litter show that shrimps are abundant the year round. Mean densities vary from 5–45 animals/m² of litter habitat. Finegrained density distribution within litter sites is highly clumped, but coarse-grained distribution in any given month between litter sites along the river is grosso-modo random.Density and species distribution are a function of the annual cycles of inundations. Of the five species (of a total of seven in the area) that were found to be breeding in the litter habitat it could be established that reproduction is restricted to the period of rising and highest water levels. Reproduction is low in all species, namely below 20 eggs per egg batch with essentially a single generation per year.Breeding ecology in relation to the litter habitat is briefly discussed.This project was supported jointly by the CNPq (Brasilian Research Council), by the OAS (Organization of the American States) and by the SUFRAMA (Financing body of local government)     

Rationalization of some genetic anticodonic assignments

The genetic code appears to be a logic matrix in which, generally speaking, there is a correlation between the hydrophobicities of amino acids and their anticodonic nucleotides. There are several exceptions to this generality, however, and using previous data on hydrophobicity and binding constants, coupled with new data on reaction rates, we rationalize several of the anticodonic assignments.     

The finding of Enterobius vermicularis eggs in pre-Columbian human coprolites

Enterobius vermicularis eggs were found in human coprolites collected in the archaeological site of Caserones, Tarapaca Valley, Chile, dating from 400 BC to 800 AD. The human pinworm had already been found in other pre-historic archaeological sites in America, and its introduction in this continent is discussed.     

Preparation of h and m antigens ofHistoplasma capsulatum free of heterologous antigens

Salt gradient elution of crude histoplasmin on CM-Sepharose CL6B at pH 3.0 was used in essentially a one-step procedure to isolate the h, m, and non-m antigens ofHistoplasma capsulatum and free them of any c antigen common to other pathogenic fungi. The h antigen fraction was pure; the isolated m and non-m antigens contained less than 0.1% of the c antigen present in the original preparation. The residual c antigen in these fractions was removed by affinity chromatography on Affigel-10 coupled to aBlastomyces dermatitidis fungal antiserum. The final preparations of h, m, and non-m were pure when tested by immunodiffusion (ID), sodium-dodecyl-sulfate-polyacrylamide-gel electrophoresis (SDS-PAGE), or electrofocusing. The antigens were serologically stable at neutral pH for at least three months at 10°C. The relative molecular weights, isoelectric points, and amino acid composition of the antigens are described.     

Stimulation of Phospholipase A2 and Secretion of Catecholamines from Brain Synaptosomes by Potassium and A23187

Abstract: Potassium depolarization of rat brain synaptosomes (containing incorporated l-acyl-2-[¹⁴C]arachidonyl-phosphatidylcholine) stimulated endogenous phospholipase A₁ (EC 3.1.1.32) and A₂ (EC 3.1.1.4), as determined by the formation of [¹⁴C]lysophosphatidylcholine, [¹⁴C]arachidonate, and [¹⁴C]prostaglandins, and also stimulated the secretion of [³H]catecholamines. The phospholipase A₂ stimulation, dependent on calcium, was elicited in resting synaptosomes by A23187 and was demonstrated with incorporated 1-acyl-2-[^l4C]oleoyl-phosphatidylcholine but not with incorporated [^I4C]phosphatidylethanolamine or [^l4C]phosphatidylserine. Inhibitors of phospholipase A₂ [p-bromophenacylbromide (10 μM), trifluoperazine (3 μM), and quinacrine (3 μM) reduced the potassium-stimulated [³H]catecholamine release from synaptosomes to 78, 39. and 55%, respectively, of depolarized controls. The addition of lysophosphatidylcholine increased the release of [³H]norepinephrine to levels observed with potassium depolarization, whereas lysophosphatidylethanolamine, lysophosphatidylserine, and sodium dodecyl sulfate were much less effective. Potassium stimulation of synaptosomes increased the endogenous levels of free arachidonic acid and prostaglandins E₂ and F_2α. Indomethacin and aspirin decreased the amounts of prostaglandins formed, allowed the accumulation of free arachidonic acid, and diminished the potassium-stimulated release of [³H]dopamine. p-Bromophenacylbromide inhibited the formation of prostaglandin F_2α. Addition of prostaglandin E₂ inhibited, whereas prostaglandin F_2α enhanced the release of [³H]norepinephrine. These results suggest that calcium influx induced by synaptosomal depolarization activates endogenous phospholipase A₂, with subsequent formation of lysophosphatidylcholine and prostaglandins, both of which may modulate neurosecretion.