Occurrence of 28- and 27-Carbon ecdysteroids and sterols in developing worker pupae of the leaf-cutting ant acromyrmex octospinosus (reich) (hymenoptera,formicidae: Attini)

The major ecdysteroids in large worker pupae of the leaf-cutting ant Acromyrmex octospinosus were characterized at the peak ecdysteroid concentration by using high-performance liquid chromatography, enzyme immunoassay, and mass spectrometry. In decreasing amounts, they were determined to be makisterone A, an unidentified C₂₈ ecdysteroid bearing a molecular weight of 494, 20-hydroxyecdysone (ratio of 1 to 6 as compared to makisterone A), and putative but negligible ecdysone. The presence of both C₂₈ and C₂₇ ecdysteroids is discussed in relation to the content of 4-desmethylsterols determined by gas chromatography and mass spectrometry to be ergosta-5,7,24 (28)-trien-3β-ol, ergosterol, ergosta-5,7-dien-3β-ol and ergosta-7,24(28)-dien-3β-ol for the main sterols, and with a small amount of cholesterol.     

The electrical and spectroscopic properties of planar asymmetrical membranes incorporating chlorophyll a and plastoquinone-9. Model of incorporation of chlorophyll a and plastoquinone-9

We have studied the incorporation of chlorophyll a and plastoquinone-9 in Montal-Mueller membranes. In particular, we have been interested by the influence of both the lipid : chlorophyll a ratio and the asymmetry of incorporation of the constituents on the electrical and fluorescence spectroscopic properties of the planar membranes built up from these constituents. The phospholipid matrix was made from phosphatidylethanolamine and phosphatidylserine. The monitoring of the fluorescence spectral properties of chlorophyll a incorporated in various concentrations leads to the conclusion that chlorophyll a is incorporated in the bilayers in monomeric form inside microdomains. It is shown that chlorophyll a is positioned in these microdomains in such a way that the porphyric ring is interacting with the polar head of the lipid molecules where the interface polarity shows a dielectric constant varying between 25 and 35. The phytyl chain is embedded in the bilayer core, serving as an anchor, running parallel to the aliphatic chains of the phospholipids. We have also monitored the position of the plastoquinone-9 molecules within the bilayer. We found that plastoquinone-9 is incorporated in the center plane of the bilayer, increasing the thickness of the bilayer. This result confirms evidence, gathered in the literature from monolayer and differential scanning calorimetry studies, that long chain quinones and especially plastoquinone-9 are embedded deeply within the hydrophobic core of the bilayer. We also show that when chlorophyll a and plastoquinone-9 are present together in the bilayer, the quinolic ring of the plastoquinone-9 molecule positions itself in the free volume created by the bulky porphyric ring of a chlorophyll a molecule.     

In vitro stimulation of human granulopoiesis by purified protein derivative (PPD)

Summary The effect of purified protein derivative (PPD) on human granulopoiesis was studied in an in vitro semisolid culture system of human bone marrow in which PPD was incorporated into the leukocyte feeder layers. We observed that preincubation of the feeder layers with PPD was necessary to induce a significant rise of agar culture colony-forming units (CFU-c) with a maximum of 3 days' preincubation and a dose of 200 g for 10 ⁶ leukocytes. A similar effect was obtained when a conditioned medium from PPD-stimulated leukocytes was used instead of feeder layers. We have found a significant correlation between the skin test response of the leukocyte donors to PPD and the colony-stimulating activity of their leukocytes exposed to PPD: these results suggest that PPD could stimulate human granulopoiesis by an indirect effect on CSF-producing mononuclear cells.     

Differential mitotic rates and patterns of growth in compartments in the Drosophila wing

In the wing disks of Drosophila slowly dividing cells of Minute mutations are progressively eliminated from Minute/Minute⁺ mosaic compartments by a process known as cell competition. From a study of two different Minutes we show here that the intensity of competition is greater in the more extreme Minute with the slowest rate of cell division. The way in which the more rapidly growing Minute⁺ clones grow and overcome the surrounding Minute cells is described and cell competition is shown to be a result of local interactions between slow- and faster-growing cells.     

Structural studies of the apoprotein of the Folch-Pi bovine brain myelin proteolipid : characterization of the CNBr-fragments and of a long C-terminal sequence.

The action of cyanogen bromide on the quite insoluble bovine proteolipid apoprotein allowed the determination of four peptide fragments: two of them constituted a 19 amino acid long C-terminal sequence of the apoprotein. Our results were in favour of the existence of only one subunit presenting a molecular weight closely related to 25,000 for which a schematic representation is given.     

Restrictive antibiotherapy after renal transplantation.

Forty-two patients were followed up after 44 renal transplantations in an effort to evaluate possible benefits from the following protocol: systematic microbiologic and clinical surveillance, early and aggressive research for the cause of suspected infections, refusal to use prophylactic antibiotherapy, and selection of treatment according to the established cause of the infection. During 18,030 days of follow-up 124 infections were recorded, of which 110 were bacterial, 11 viral and 3 protozoal. Eighty originated in the urinary tract, 17 in skin wounds and 10 in the lower respiratory tract. Septicemia occurred three times, and one death due to infection was recorded. In the treatment of bacterial infections patients received antibiotics for 2486 days. Ampicillin (given for 816 days) and "minor" drugs such as sulfonamides and urinary antiseptics (given for 1036 days) were used 74.5% of the time, whereas gentamicin was used only 2.6% of the time (64 days). Combined antibacterial therapy was needed 1.2% of the time (29 days). A restrictive policy regarding anti-biotherapy seems to be beneficial to renal transplant recipients.