Regression of blood vessels precedes cartilage differentiation during chick limb development

We have previously investigated distinct areas of vascular regression in the developing vascular system of the chick limb bud. Avascular areas appear in a characteristic spatial and temporal pattern, and are correlated with the position of developing cartilage. In the present study, we examined limb-bud sections which had been double labeled for endothelial cells and developing cartilage in order to determine the relationship between the appearance of cartilage and the disappearance of capillaries. Endothelial cells, which specifically take up acetylated low-density lipoprotein (acLDL), were labeled by intravenously injecting fluorescent acLDL (DiIacLDL) into chick embryos at Hamburger and Hamilton stages 26-30. Avascular zones, which correspond to the developing digits, were clearly visible within the fluorescently labeled distal vasculature. The same sections were labeled with monoclonal antibodies specific for cartilage. We found that progressing avascularity in the digital regions was followed by increased staining for cartilage antigens in the same areas. Zones of avascularity always developed earlier than morphologically and immunologically detectable cartilage in all planes of section and were always larger than the areas of cartilage. These results demonstrate that blood vessels disappear in predictable areas prior to the overt differentiation of cartilage.     

Effects of nucleotides and divalent cations on phospholipase activity in Saccharomyces cerevisiae

Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 M. The inhibition by nucleotides in low concentrations is enhanced by divalent cations.     

Continuous microbial desulfurization of coal--application of a multistage slurry reactor and analysis of the interactions of microbial and chemical kinetics

Microbial desulfurization of coal by pyrite oxidizing bacterial enrichment cultures has been studied in air-agitated slurry reactors of 4- and 20-L volumes. Batch experiments showed that inoculation with an active bacterial culture is essential to minimize the lag phase, although a considerable number of pyrite oxidizing bacteria was found on the coal prior to desulfurization. For detailed investigations of kinetics, energy requirements, and technical applicability, a bioreactor equipment consisting of a cascade of eight stages was developed and operated continuously. Microbial desulfurization of coal-monitored by measuring the axial profile of dissolved iron concentration, real and maximum oxygen consumption rates, and cell concentration-at pulp densities to 30% was performed over a period of 200 days without any disturbances concerning the aeration system, fluidization, transport of solids and microbial growth. At a pulp density of 20%, a pyrite conversion of 68% was achieved after the third reactor stage at a total residence time of five days in the first three stages. The kinetics of pyrite degradation were found to be well described by a rate equation of first order in pyrite surface area concentration if the pyrite is directly accessible for microbial attack. Rate constants were determined to 0.48 mg pyrite/(cm(2) day) in the first and to 0.24 mg pyrite/(cm(2) day) in the following reactor stages. Kinetic models taking into account adsorption/desorption as well as growth kinetics failed to describe the observed reaction rates. However, a model treating pyrite degradation and microbial growth kinetics formalistically seems to be applicable when backmixing between the reactor stages can be avoided. The advantage of a multistage reactor in comparison to single-stage equipment was shown by calculation. To obtain a pyrite conversion of 68%, a three-stage reactor would require only 58% of the volume of single-stage equipment.Measurement of oxygen consumption rates proved to provide quickly and easily measurable parameters to observe microbial coal desulfurization in technical scale: the real oxygen consumption rate is correlated to the pyrite oxidation rate and the maximum oxygen consumption rate is correlated to the concentration of viable cells. The Y(o/s) coefficient for the amount of oxygen consumed per mass unit of pyrite oxygen was determined to approximately 0.33 in comparison to 1.0 which can be calculated from stoichiornetry. This could yet not be explained. Chemical leaching experiments as well as sulfur analyses of desulfurized coal samples showed that the microorganisms play the main role in degradation of pyrite from coal and that pyrite oxidation by ferric iron can be neglected.     

Characteristics of the pulmonary transport functions for heat and dye in pulmonary edema and orthostasis

The aim of this study was to investigate whether changes in the distribution of pulmonary blood flow and disturbances of the pulmonary microcirculation can be detected by use of inflow-outflow indicator-dilution measurements. In 18 anesthetized (N2O-piritramide) mongrel dogs 221 thermal-indocyanine green dye indicator dilution kinetics were recorded in the pulmonary artery and aorta after central venous indicator injection. The lagged normal density function was used as a model for the pulmonary transport functions for heat and dye. The parameters of the lagged normal density function were computed by a non-linear least squares procedure by iterative convolution. After baseline measurements, in nine dogs, pulmonary edema was induced by central venous application of oleic acid. In nine other dogs, measurements were performed before and after postural changes. Our data show that both the microvascular injury caused by oleic acid edema and the perfusion heterogeneity caused by orthostasis can be detected by the indicator dilution technique since the both relative dispersion and skewness of the transport functions for heat and dye were significantly increased after these interventions.     

Protein S binding in relation to the subunit composition of human C4b-binding protein

The human regulatory complement component C4b-binding protein (C4BP) circulates in plasma either as a free protein or in a bimolecular complex with the vitamin K-dependent protein S. The major form of C4BP is composed of 7 identical, disulfide-linked 70 kDa subunits (alpha-chains), the arrangement of which gives the C4BP molecule a spider-like appearance. Recently, we identified a unique 45 kDa subunit (beta-chain) in C4BP. We have now isolated a subpopulation of C4BP, which does not bind protein S. This C4BP species, which had a molecular weight slightly lower than that of the predominant form, was found to lack the beta-chain. Another lower molecular weight form of C4BP was also purified. It contained the beta-chain and was efficient in binding protein S. Its subunit composition was judged to comprise six alpha-chains and one beta-chain. These results indicate C4BP in plasma to be heterogeneous at a molecular level vis-a-vis subunit composition and/or protein S binding ability and provide support for the concept that the beta-chain of C4BP contains the single protein S binding site.     

A new facultatively nitrite oxidizing bacterium,Nitrobacter vulgaris sp. nov.

A total of 17 facultatively lithoautotrophic strains of Nitrobacter were investigated. They all were found to be related on the species level by DNA hybridizations. The G+C content of DNA ranged between 58.9 and 59.9 mol %. The isolates originated from divers environments. The cells were 0.5–0.8×1.2–2.0 m in size and motile by one polar to subpolar flagellum. Cell-division normally occurred by budding. Polar caps of intracytoplasmic membranes as well as carboxysomes were present. The cells tended to excrete extracellular polymers forming aggregates or biofilms. Heterotrophic growth was slower than mixotrophic but often faster than litoautotrophic growth. In the presence of nitrite and organic substances the organisms often showed diphasic growth. First nitrite and then the organic material was oxidized. In the absence of oxygen growth was possible by dissimilatory nitrate reduction. Nitrite, nitric and nitrous oxide as well as ammonia were formed. Depending on growth conditions the generation times varied from 12 to 140 h. The new Nitrobacter spec. may be one of the most abundant nitrite-oxidizing bacteria in soils, fresh waters and natural as well as artificial stones. For this organism the name Nitrobacter vulgaris is proposed.The type strain is filed with the culture collection of the Institut für Allgemeine Botanik, Universität Hamburg, FRG.     

A dynamic theory of coordination of discrete movement

The concepts of pattern dynamics and their adaptation through behavioral information, developed in the context of rhythmic movement coordination, are generalized to describe discrete movements of single components and the coordination of multiple components in discrete movement. In a first step we consider only one spatial component and study the temporal order inherent in discrete movement in terms of stable, reproducible space-time relationships. The coordination of discrete movement is captured in terms of relative timing. Using an exactly solvable nonlinear oscillator as a mathematical model, we show how the timing properties of discrete movement can be described by these pattern dynamics and discuss the relation of the pattern variables to observable end-effector movement. By coupling several such component dynamics in a fashion analogous to models of rhythmic movement coordination we capture the coordination of discrete movements of two components. We find the tendency to synchronize the component movements as the discrete analogon of in-phase locking and study its breakdown when the components become too different in their dynamic properties. The concept of temporal stability leads to the prediction that remote compensatory responses occur such as the restore synchronization when one component is perturbed. This prediction can be used to test the theory. We find that the discrete analogon to antiphase locking in rhythmic movement is a tendency to move sequentially, a finding that can also be subjected to empirical test.     

Susceptibility of autologous target cells to lysis by lymphokine-activated effectors from interferon-α-treated chronic myelogenous leukaemia patients

Summary Chronic myelogenous leukemia (CML) patients in chronic phase display compromised lymphokine-activated killer (LAK) cell induction, which is partly restored after therapy with interferon . However, the relative resistance of the leukemic cells from these patients to autologous or allogeneic LAK lysis is not affected by this treatment. In an attempt to render CML cells more susceptible to lysis or cytostasis, they were precultured in serum-free medium with or without recombinant growth factors. In eight patients studied, interleukin-3 (IL-3) significantly enhanced the spontaneous short-term (6-day) proliferation of CML cells, with retention of ability to form colonies in methylcellulose. Culture in either medium alone or IL-3 led to a significant enrichment of CD14⁺ and CD33⁺ cells but to a reduction in CD34⁺ cells. In contrast, culture of the same cells in IL-2 (to generate autologous LAK activity) resulted in a loss of CD14⁺ and CD33⁺ as well as CD34⁺ cells but in a significant increase in CD3⁺ and CD56⁺ cells. Despite similarities in their phenotypes, IL-3 cultured cells but not those cultured in medium alone acquired susceptibility to lysis by the IL-2-cultured autologous LAK cells. These results may have significance for the design of novel combination immunotherapy in CML.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 120)     

Linkage of the DNA-segment D7S13 (pB79a) with the cystic fibrosis locus

Summary A map distance of 2.9 cM between D7S13 (pB79a) and the cystic fibrosis (CF) locus was obtained from the analysis of 13 informative families with a history of CF. This result is based solely on the HindIII restriction fragment length polymorphism (HindIII-RFLP) at D7S13, since the interpretation of the Msp1-RFLP at this locus was found to be unreliable.