The use of percoll gradients, elutriator rotor elution, and mithramycin staining for the isolation and identification of intraerythrocytic stages of plasmodium berghei

Intraerythrocytic parasites of Plasmodium vinckei and Plasmodium berghei were separated according to their developmental stages using discontinuous Percoll gradients. Contaminating nucleated blood cells such as leukocytes were removed by elutriation centrifugation. The stages were unequivocally identified in smears using a newly developed DNA-specific staining procedure with mithramycin and fluorescence microscopy. This stain can also be used to detect parasites in human blood of very low parasitemias. The combination of methods described has many possible applications in immunologic and biochemical parasite research.     

Development in ontogeny of the effect of ACTH fragment 4-7 on rat learning

Studies have been made of the effect of ACTH fragment 4-7 on learning in rats in early postnatal ontogenesis, as well as of the possibility of preservation of early learning during administration of this peptide to adult animals. It was shown that conditioned reaction of active avoidance practically cannot be formed in normal 13-15-day animals; however, administration of ACTH 4-7 increases the number of animals exhibiting adequate reactions. Weak effect of ACTH 4-7 in 12-15-day animals, in older ones (20-24 days) is changed by a significant stimulating effect.     

Ultrastructure of the sporophyte foot-gametophyte vaginula complex inTimmiella barbuloides (Brid.) Moenk

The sporophyte foot of the mossTimmiella barbuloides consists of an unistratose epidermis of transfer cells, a parenchymatous cortex, and a small central strand consisting only of hydroids. The parenchymatous tissue of the vaginula develops one layer of transfer cells opposite the foot, whose lower extremity extends into the gametophyte stem's central strand. From the bottom to the top of the foot the ultrastructure of the sporophyte transfer cells shows some gradual changes that appear related to a functional specialization of these cells. According to a centripetal gradient, the quantity of plastid starch progressively lessens in both vaginula parenchyma and foot cortex. the observed morphological patterns suggest that in the foot-vaginula complex nutrients are translocated radially up to the sporophyte central strand.     

A Sphincter in the Pulmonary Artery of the Frog Rana temporaria and Its Influence on Blood Flow in Skin and Lungs

A sphincter is described in the a. pulmonalis in the frog Rana temporaria. The sphincter begins abruptly where the pulmonary artery branches off from the a. pulmo-cutanea. It is constricted by vagal stimulation and acetylcholine. It also contracts actively when the lungs are artificially collapsed and opens when the lungs are inflated. It is suggested that previously reported fibers in the vagus nerve, which come from stretch receptors in the lungs, act as the afferent reflex arch. When the pulmonary artery constricts, the cutaneous artery and vein are distended by increased pressure which contributes to increased cutaneous flow. The sphincter therefore seems to play an important role in the adjustment of circulation to exclusive cutaneous respiration as for instance in submerged, wintering frogs. It is suggested that the decrease of pulmonary flow in such situations causes increased mixing in the heart and, perhaps, complete break-down of the double circulation. In frogs with exclusive skin respiration this would seem to be a functional necessity. Sphincters of similar location in turtles seem to be homologous with the one in Rana.     

An enyzmic method for the analysis of D-erythrose 4-phosphate.

Two modifications of an enzymic method for the measurement of erythrose 4-phosphate, based on reactions catalyzed by transketolase, are described. Unlike the method generally employed, the new procedure is sensitive and highly specific and applicable to the assay of erythrose 4-phosphate in tissue extracts.     

Analysing the patterning of a sequence of discrete behavioural events

Existing techniques for analysing the organization of behavioural events are discussed. Cluster analysis, mutual replaceability, ‘melody’ detection and Markov analyses are examined in order to discover the validity and usefulness of the concepts searched for by each technique, and the mathematical and statistical background of the techniques is scrutinized. Some new techniques, designed to search for and detect possible important sequential organization patterns, are described in the light of the previous criticisms. Of these techniques, the Pre-post-state Histogram (PPSH)—a multi-order Markov graphical analysis—would appear to be the most important for future work, especially when used in conjunction with the other techniques described.     

Incidence of squatting facets on the talus of Indians (Agra region).

230 adult Indian tali (from Agra region) were studied for the incidence of squatting facets. Extension of medial articular facet was observed in all the cases. Medial extension of trochlea was observed in 37% of cases; lateral extension of trochlea in 71.6% of cases, lateral squatting facets in 43.5% of cases and medial squatting in 8.6% of cases. The present data are compared with that of other workers.     

Column chromatography of plant polyphenols on weak anion exchangers.

Mixtures of phenols and cinnamic acid derived plant polyphenols are separated on several WAX cellulose materials and on DEAE Sephadex. Reference mixtures are also split up into the following distinct groups: phenolic carboxylic acids--neutral o-dihydroxy phenolics--neutral non o-dihydroxy phenolics. Quantitative recoveries are obtained, while no isomerizations occur with the pH labile plant phenolics. It is suggested that these materials can be used for preparative scale purification of plant phenolics, or for cleaning up plant extracts prior to HPLC examination.