A simple technique for testing the in vitro response of rabbit lymphocytes to PHA and allogeneic cells.

Lymphocytes of rabbits can be separated from small quantities of heparinized whole blood using a simple density gradient of Ficoll-Ronpacon 1.09. This separation technique yields a pure suspension of viable cells allowing reproducible results from cultures stimulated either with PHA or allogeneic lymphocytes isolated by the same technique.     

Multiplicity of beta lactamases: a problem of isoenzymes]

Analytical isoelectric focusing of beta lactamases is a very sensitive and powerful technique which generally shows a number of satellites near the main enzymatic spike. By this technique we studied two bacterial groups known to produce different beta lactamases, but only one by germ. Analytical isoelectric focusing showed that all bacteria from the same group produce the same satellite system which differs only in relative activity.     

A successive filtering technique for identifying long-term trends

The most reliable component of a time series, for forecasting purposes, is the shape of the long-term trend. However, the presence of cycles makes it difficult to identify and predict the changes in such trends. While up to now emphasis has been given in identifying and measuring cyclical behaviour, this paper presents a technique that aims at removing cyclical effects from the long-term trends. This technique is based on a transformation that is successively applied on the original time series. Each time the transformation is applied, an observation is selected and replaced by the average of its adjacent observations. This results in the elimination of the cyclical component. Independently of their depth, the cycles are being removed in ascending order relatively to their length. This leads to 'brushing off' the long-term trends from any cyclical effects. A specialized software has been developed in Pascal. The proposed technique was applied in a set of time series from the M2- and M-competition and the results are presented in this paper.     

Self-labeling of human polymorphonuclear leucocyte myeloperoxidase with 125iodine.

In order to obtain a radioimmunoassay (RIA) technique for the measurement of human plasma myeloperoxidase (MPO), we purified the enzyme from polymorphonuclear granulocytes (neutrophils), and compared three methods of labeling it with 125Iodine:chloramine T, lactoperoxidase, and an original technique of 'self labeling' based on the ability of the enzyme to oxidize and bind 125I in the presence of H2O2. The chloramine T technique produced a degraded protein, as well shown by a high non-specific binding of tracer to antibody. The lactoperoxidase technique did not succeed in labeling MPO with an adequate specific activity. In contrast, the self-labeling method gave a stable tracer with a specific activity of 23 microCi/micrograms MPO (85 MBq), a satisfactory level of immunoreactivity, and a low-specific binding (less than or equal to 3%). After labeling, purification of tracer was achieved by gel filtration chromatography in phosphate buffer (0.05 M; pH7) to which 0.1% poly-L-lysine was added. The labeled molecule remained stable for 40 days and could be used for RIA with a polyclonal antibody raised in rabbits.     

Giemsa `and formation in M-chromosomes of Vicia faba

Summary Various alterations in Giemsa banding technique have been introduced to observe their influence on band formations in M-chromosome of Vicia faba root tip dividing cells. With the introduction of some minor alterations in the technique, revelation of a large number of classes of constitutive heterochromatin has been made possible. Apparently such Giemsa banding pattern is comparable to the ones observed in a routine way amongst mammalian chromosomes.Acknowledgments. This study was supported by a grant from the Council of Scientific and Industrial Research, New Delhi (No. 7/13 [619]/72 GAU. I), to JPG and from the Indian National Science Academy, New Delhi (No. 31/BS/323), to SKS.     

Algorithmic compression of empirical data: reply to Twardy, Gardner, and Dowe

This discussion note responds to objections by Twardy, Gardner, and Dowe to my earlier claim that empirical data sets are algorithmically incompressible. Twardy, Gardner, and Dowe hold that many empirical data sets are compressible by Minimum Message Length technique and offer this as evidence that these data sets are algorithmically compressible. I reply that the compression achieved by Minimum Message Length technique is different from algorithmic compression. I conclude that Twardy, Gardner, and Dowe fail to establish that empirical data sets are algorithmically compressible.     

Effects of Ca2+ and Mg2+ on motility of sea urchin spermatozoa

Summary Swimming speed of sea urchin spermatozoa, measured by a light scattering technique, did not change with 0-20 mM Ca²⁺ in the medium. The speed was maximum at the normal concentration of Mg²⁺ (49 mM) in sea water.Supported by grants-in-aid from the Ministry of Education, Science and Culture, Japan, and a grant from the Ford Foundation.     

A rapid electrophoretic method for the separation of hydroxyproline from proline

Summary A rapid, sensitive procedure is described which uses custom made apparatus to separate radioactive imino acids. This technique provides a simple measurement of the distribution of newly synthesized collagen in different fractions.Acknowledgment. This work was supported by grants from the International Wool Secretariat.     

Development of plasma cortisol in calves from birth to 14 days of age]

Plasma cortisol was recorded in 15 calves from birth to 14 days of age by a radio-immunoassay technique. At birth mean cortisol value is 67.3 ng/ml; 6 hrs. later it decreases by 58.4% then it gradually diminishes and about 14 days after, it reaches adult levels (5.1 ng/ml).     

In vitro study of cellular affinity to various protein supports suited for vascular prosthesis]

We compare the affinity of different cellular samples with regard to variosu artificial materials by organotypic culture method. We use a technique which allows at once, to obtain the cells and to measure their migration on the artificial surface. The results show a high variation of the cellular affinity from one sample to another.     

Prefrontal cortex of the cat: evidence for an additional area.

Direct projections from the mediodorsal nucleus of the thalamus to ventral parts of the insular region of the cat's cortex were demonstrated by using the horseradish peroxidase technique.     

Chromatofocusing coupled with automated assay for beta-hexosaminidase isoenzymes in GM2 gangliosidosis

Good separations of the two major beta-hexosaminidase forms from human leukocytes were achieved by chromatofocusing, a technique which separates proteins on the basis of their isoelectric points. The use of an automated and reliable method is described for the identification of homozygotes and carriers of the GM2 gangliosidosis.     

Prefrontal cortex of the cat: Evidence for an additional area

Summary Direct projections from the mediodorsal nucleus of the thalamus to ventral parts of the insular region of the cat's cortex were demonstrated by using the horseradish peroxidase technique.     

Sensory projections from dorsal and ventral appendages inDrosophila grafted to the same site are different

Summary Owing to a new transplantation technique, we have been able to study the sensory projections of homologous and heterologous appendages grafted to the same abdominal site inD. melanogaster. Axons from homologous transplants exhibit similar terminal patterns, whereas those from heterologous transplants do not. It is suggested that ectopic sensory axons specifically recognized central areas and pathways occupied by axons from homologous appendages.     

Use of a new process of metallic shadowing by cathodic vaporization for scanning electron microscopy of tegumental products of insects]

In scanning electron microscopy, the recent process, not yet much used, of coating subjects with gold by cathodic sputtering, allows one in biology and especially in entomology, to visualize microreliefs, habitually masked, when the old technique called evaporating technique, was used. This process effectively allows one to deposit a very much thinner layer of metal and, because it is performed at room temperature, prevents artifacts caused by the high temperature necessitated by the other technique, whose previous results nevertheless remain generally correct.     

Monoamine oxidase activity in single nerve cell bodies from substantia nigra of rat and man

In single nerve cell bodies isolated from the substantia nigra of man and rat the active forms of MAO A and MAO B were found by the use of the microdiver technique and specific inhibitors.     

Monoamine oxidase activity in single nerve cell bodies from substantia nigra of rat and man

Summary In single nerve cell bodies isolated from the substantia nigra of man and rat the active forms of MAO A and MAO B were found by the use of the microdiver technique and specific inhibitors.     

A comparison between the free grafting of sliced and intact muscles in the rat

Summary Transverse slicing is a new technique whereby a mammalian muscle can be freely grafted with success. This method eliminates contamination of the early graft by surviving muscle fibres and allows one to measure the development of contractile properties on a uniform population of regenerating muscle fibres.Supported in part by a grant from the Muscular Dystrophy Associations of America, Inc.Part of this research was carried out while on a scientific exchange between the US and Czechoslovak Academies of Sciences.     

Stereoselectivity of a radioimmunoassay for the insecticide S-bioallethrin

Summary The stereoselectivity of a radioimmunoassay (RIA) system using an S-bioallethrin specific antiserum was studied by observing the abilities of the 8 allethrin isomers and other selected compounds to compete with a radiolabelled S-bioallethrin tyramine derivative for antibody binding sites. The results demonstrate the feasibility of RIA as a rapid, sensitive and stereoselective residue technique for compounds difficult to analyze by classical methods.This work was supported in part by grant No. 5-R01-ES01260-02 from the National Institutes of Health.