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Notes: Abstract The ability of rat lung to remove the local anaesthetic drug bupivacaine from the blood was studied in isolated organs which were perfused either in an open (single-pass mode) or in a closed system (recirculating medium). Isolated perfused rat lungs exhibited a very low capacity to metabolize bupivacaine within 3 h during which the drug circulated continuously through the organ. The clearance values differed only by 0.2 ml/min from the control parameters in sham perfusions. The calculated extraction ratio was 0.2% and the elimination half-life was about 210 min. The volume of distribution of bupivacaine was 133 ml which remarkably surmounted the reference values obtained for sham perfusions. The distribution of bupivacaine into the pulmonary tissue was investigated applying the multiple indicator dilution technique to isolated lungs perfused in the single-pass mode. The mean elimination time of model compounds for distribution into the intravascular space, 14C-inulin, and the total water space, 3H-water, were 68 and 75 s at a flow rate of 6 ml/min. The volume of distribution was 5.9 ml for inulin and 6.5 ml for water. The mean transit time for concomitantly injected bupivacaine was 221 s and the volume of distribution was 14.4 ml. The respective parameters of sham perfusions performed without an isolated organ were substantially lower, i.e. mean elimination time 50, 50 and 61 s and distribution volume 4.9, 5.0 and 6.1 ml for inulin, water and bupivacaine. The volume of distribution during single-pass contact of bupivacaine to lung was not substantially influenced by an increase of the flow rate from 6 to 9 and 12 ml/min whereas the mean transit time dropped from 221 to 121 and 108 s, respectively. These results support the assumption that bupivacaine is extensively retained by the pulmonary tissue and that elimination of bupivacaine by metabolism can be neglegted for lung. The hemodynamic parameters of bronchiolar perfusion in the artificially perfused lung were determined using two fluorochrome-labeled macromolecular proteins, i.e. fluorescein-isothiocyanate (FITC)- and lissamine-rhodamine-B 200 (RB 200)-labeled globulin. After 10 min of perfusion at a flow rate of 12 ml/min in the closed system an area of 10.8070 of the peribronchiolar tissue area contained the dye-label FITC. A very similar index (10.1%) of dye-coloured capillaries was obtained when the lungs of anaesthetized rats were examined 10 min after intravenous injection of the fluorochrome into the pulmonary artery in vivo. In isolated perfused rat lungs receiving both FITC and RB 200 59.5% of FITC-labeled capillaries were reached by the second fluorochrome within 2 s. This fraction accounted for 93.3% after 10 s of circulation time. This proves that isolated rat lungs were well perfused in vitro.

Notes: Abstract The ability of rat lung to remove the local anaesthetic drug bupivacaine from the blood was studied in isolated organs which were perfused either in an open (single-pass mode) or in a closed system (recirculating medium). Isolated perfused rat lungs exhibited a very low capacity to metabolize bupivacaine within 3 h during which the drug circulated continuously through the organ. The clearance values differed only by 0.2 ml/min from the control parameters in sham perfusions. The calculated extraction ratio was 0.2% and the elimination half-life was about 210 min. The volume of distribution of bupivacaine was 133 ml which remarkably surmounted the reference values obtained for sham perfusions. The distribution of bupivacaine into the pulmonary tissue was investigated applying the multiple indicator dilution technique to isolated lungs perfused in the single-pass mode. The mean elimination time of model compounds for distribution into the intravascular space, 14C-inulin, and the total water space, 3H-water, were 68 and 75 s at a flow rate of 6 ml/min. The volume of distribution was 5.9 ml for inulin and 6.5 ml for water. The mean transit time for concomitantly injected bupivacaine was 221 s and the volume of distribution was 14.4 ml. The respective parameters of sham perfusions performed without an isolated organ were substantially lower, i.e. mean elimination time 50, 50 and 61 s and distribution volume 4.9, 5.0 and 6.1 ml for inulin, water and bupivacaine. The volume of distribution during single-pass contact of bupivacaine to lung was not substantially influenced by an increase of the flow rate from 6 to 9 and 12 ml/min whereas the mean transit time dropped from 221 to 121 and 108 s, respectively. These results support the assumption that bupivacaine is extensively retained by the pulmonary tissue and that elimination of bupivacaine by metabolism can be neglegted for lung. The hemodynamic parameters of bronchiolar perfusion in the artificially perfused lung were determined using two fluorochrome-labeled macromolecular proteins, i.e. fluorescein-isothiocyanate (FITC)- and lissamine-rhodamine-B 200 (RB 200)-labeled globulin. After 10 min of perfusion at a flow rate of 12 ml/min in the closed system an area of 10.8% of the peribronchiolar tissue area contained the dye-label FITC. A very similar index (10.1%) of dye-coloured capillaries was obtained when the lungs of anaesthetized rats were examined 10 min after intravenous injection of the fluorochrome into the pulmonary artery in vivo. In isolated perfused rat lungs receiving both FITC and RB 200 59.5% of FITC-labeled capillaries were reached by the second fluorochrome within 2 s. This fraction accounted for 93.3% after 10 s of circulation time. This proves that isolated rat lungs were well perfused in vitro.

Notes: Neben den1 Chlor-1-fluorid besteht auch ein Chlor-3-fluorid, welches durch Erhitzen von CI2 oder CIF mit überschüssigem F2 dar- gestellt wird. Die umkehrbare Reaktion CIF + F2 ⇆ CIF3 führt zu einem Gleichgewicht, in dem bei 250° Zahl der CIF-Moleküle ein Mehrfaches der CIF3-Moleküle ist. Die Zusammensetzung des neuen Fluorids is durch Analysen und Dichtebestimmungen sichergestellt. Seine physikalischen und chemischen Eigenschaften werden mit - geteilt.Besonders bemerkenswert ist die Lebhaftigkeit und die Mannigfaltigkeit der Reaktionen des CIF3.

Notes: Für definierte Schmelzbedingungen wird die Glasbildung in den Systemen Tl—Ge—Se und PbSe—GeSe2—Se beschrieben. Bei hohen Selen- und geringen Germaniumgehalten treten in beiden Fällen ausgedehnte Gebiete mit Mikro- und Makrophasentrennung auf. Zur Festlegung des Konnodenverlaufs in den Mischungslücken werden naßchemische Analysen, rasterelektronenmikroskopische Untersuchungen und Mikrohärtemessungen herangezogen. Für die Transformationstemperaturen Tg und die Mikrohärten HMV homogener Tl—GE—Se-Gläser ergeben sich lineare Abhängigkeiten von den Näherungswerten ΔAH1 für die molare Atomisierungsenthalpie der Proben.

Notes: Die Einwirkung von NaF und Na2SiF6 auf SiO2 und Natriumsilicate wurde untersucht. Das zugleich entstehende SiF4 beeinflußt den Reaktionsablauf, wie ein Vergleich der Versuche im offenen und geschlossenen System zeigt. Bei geringem SiF4-Druck führen Umsetzungen von NaF oder Na2SiF6 mit einigen SiO2-Modifikationen zu Natriumsilicaten, bei merklichen Drucken von SiF4 zu Cristobalit, Tridymit und auch zu T-Quarz.Viele Natriumsilicate gehen mit NaF vorzugsweise in Na2SiO3 über. Na6Si8O19 entstand aus Na2SiO3, war aber nur mit Na2SiF6 statt NaF zu erhalten; dabei trat auch T-Quarz auf. Die an das Vorhandensein gewisser Fremdionen gebundene Bildung von Tridymit ließ sich bei hoher Temperatur (1150°C) erreichen, wenn HF zusammen mit einem der Alkalifluoride (A = Na, K, Rb, Cs) zugegeben wurde. Die Menge des Zusatzes war entscheidend für die Größe der über eine chemische Transportreaktion entstehenden Tridymitkristalle. Die im eingesetzten T-Quarz (Furka) enthaltenen Verunreinigungen reichen für die Bildung von Tridymit nicht aus.

Notes: Beim Erhitzen von Niob(IV)-oxid mit Lithium-, Natrium- und Kaliumfluorid entestehen Verbindungen vom Typ MeINbO2F mit Perowskitstruktur. LiNbO2F Kristallisiert rhomboedrisch, NaNbO2F rhombisch, KNbO2F kubisch. Die Verbindungen besitzen einen schwachen, temperaturunabhängigen Paramagnetismus und sehr geringe elektrische Leitfähigkeit.

Notes: Although homogeneous in appearance, several lines of evidence suggest early (stage 17 - 19) limb mesenchymal cells are committed to particular cell lineages, e.g., myogenic or chondrogenic. However, subsequent expression of cell or tissue phenotype in the developing limb does not occur in a randomized process but rather in a spatially specific pattern. The potential regulatory mechanisms controlling the “patterned” expression of tissue phenotype in the limb have not been resolved. The purpose of this study was to determine if, prior to the formation of an apical ectodermal ridge, nondissociated limb mesenchyme has inherent morphogenetic potential to form nonrandomized patterns of tissue organization. The hypotheses to be tested were that, if provided a spatially permissive culture environment, (1) mesenchymal cells committed to a particular lineage would segregate into precursor (sub)populations prior to overt expression of phenotype and (2) the ultimate expression of a tissue phenotype may be regulated, in part, by histogenic interactions between the precursor cell groups. For these studies, mesoblasts (intact mesenchyme minus ectoderm) from stage 17 - 19 hindlimb buds were explanted intact to the surface of a 1 - 3 mm thick hydrated lattice of repolymerized type I collagen and incubated for 2 - 11 days. Examination of cultures at variable intervals revealed three distinct temporal sequences (periods) which were arbitrarily termed early morphogenesis (0 - 3 days), cytodifferentiation (3 - 5.5 days), and primitive tissue formation (5.5 - 11 days) based on similarities to in situ limb development. By the end of the first period, the mesenchymal cells had sorted into three distinct precursor populations: (1) an epithelial-like outgrowth of premyogenic and prefibrogenic cells at the surface of the gel lattice (termed the “surface subset”) which circumscribed, (2) a centrally positioned prechondrogenic condensate (“central subset”), and overlaid (3) a dispersed, population of free cells that invaded the collagen lattice (“seeded subset”). Subsequent cytodifferentiation led to the appearance of multinucleated myotubes within the surface subset and chondrification of the central subset. Cells of the seeded subset remained dispersed within the collagen lattice. Primitive histogenic events were initiated during the final period of development including (1) at sites where surface cells established boundaries with the central subset, collectives or “bundles” of variable sized myotubes were formed which became partially ensheathed by the attenuated processes of fibroblastlike cells; and (2) a secondary site of chondrogenic activity was initiated within the gel lattice at the boundary between the central and seeded cell populations. Transformation of seeded fibroblasts into chondroblasts accompanied expansion of the secondary chondrogenic element within the gel lattice. Remaining cells of the seeded population which did not become incorporated (transformed) into the secondary site of chondrogenesis persisted as a dense stratified network of fibrous connective tissue. Removing the central subset after 2 days of culture inhibited the transformation of seeded fibroblasts into chondrogenic cells.These findings indicate that intact limb mesenchyme prior to the formation of a mature apical ridge and in the absence of dorsal/ventral ectoderm has the endogenous potential to segregate, cytodifferentiate, and interact to intiate tissue formation similar to that seen in the intact limb.

Notes: Cells derived from an epithelial-mesenchymal transformation within the atrioventricular canal and outflow tract are involved in the partitioning of the early embryonic heart into a four-chambered organ. This transformation process has been shown to proceed from an inductive interaction between the myocardium and competent, target endothelial cells within these regions of the heart. Interestingly, immunohistochemistry revealed the presence of fibronectinpositive particulates within the matrix of mesenchyme-forming regions (Mjaatvedt et al., 1987). This particulate matrix is extractable by EDTA and can elicit the epithelial-mesenchymal transformation in culture (Mjaatvedt and Markwald, 1989). Analysis of EDTA extracts of embryonic heart tissue revealed the presence of fibronectin and about 40 unidentified proteins, 6 of which appeared to be enriched in the biologically active 100,000g pellet fraction (Mjaatvedt and Markwald, 1989). Based on these and other data we have proposed that the particulate matrix is composed of a multicomponent complex of fibronectin and one or more of the low-molecular-weight proteins in this pellet. The purpose of the present study was to begin a biochemical characterization of the nonfibronectin proteins thought to be present in the matrix particulates. Given that many matrix constituents are glycoproteins, lectins were used to initially characterize the particulate constituents. Of the lectins tested, soybean agglutinin (SBA) was found to be specific only for matrix particulates. Histochemical analyses showed that SBA and antibodies against fibronectin colocalized regionally and temporally to the same matrix particulates in embryonic heart tissue. SBA-agarose affinity chromatography resulted in the isolation of two major (56 and 69 kDa) and six minor (28, 46, 50, 53, 126, 220 kDa) proteins from EDTA extractable heart matrix. Temporal lectin histochemical studies indicate that SBA-positive particulates are present in the matrix prior to mesenchyme formation, but are absent shortly after the transformation event. These observations support our hypothesis that one or more of these SBA-positive glycoproteins participate in the endothelial-mesenchymal transformation of cardiac endothelium.

Notes: Recent in situ hybridization studies have correlated expression of potential regulatory genes with pattern formation in limb bud mesoderm (Tabin: Cell 66:199-217, 1991); however, the mechanism(s) controlling their expression in mesoderm and their relevance to the establishment of a limb morphogenetic pattern remain unknown. One likely candidate for regulating patterning events in limb mesoderm is the apical ectodermal ridge, as its removal in ovo results in a graded truncation of limb skeletal elements in the proximal-distal axis dependent upon the time of excision (Rowe and Fallon: J Embryol Exp Morph 68:1-7, 1982). In the present study, we investigate whether the hypothetical imprint of ridge ectoderm is retained in cultured mesoderm. Specifically, we sought to determine if a subpopulation of limb mesoderm that forms in collagen gel culture (Markwald et al: Anat Rec 226:91-107, 1990), retains any expression of “limbness” in the absence of limb ectoderm as characterized by the formation of a predictable number and distribution of limb-like chondrogenic elements in comparison to the temporal and spatial relationships of the in situ proximal, hindlimb skeletal structures. Accordingly, explants of undissociated mesoderm from stage 18-22 chicken leg buds were cultured without ectoderm on collagen gel lattices and the central subpopulation of mesoderm was examined morphologically. We show that this central subset of mesoderm will form chondrogenic cells which were not expressed uniformly throughout the subset, but rather distinct nodules or elements of cartilage were elaborated. Moreover, the number of elements expressed by the central subset increased with the age of the mesoderm at the time of explantation; spatially and temporally, the sequence of elements that formed always proceeded from the proximal, anterior margin of the subset to its distal, posterior border. The shapes of the initial elements (designated I and II) resembled the forms of in situ proximal skeletal structures (girdle and femur-like), whereas more distal elements (III-V) were often fused and without structural similarity to in situ skeletal structures. When cultures were established from the posterior mesoderm of stage 19/20 or 21 mesoblasts, the frequency of element I formation was reduced approximately one-half, whereas formation of more distal elements was unaffected. Conversely, element formation from the central subset established from isolated anterior mesoderm was virtually identical to intact mesoblasts, indicating a capacity to regulate for the loss of mesoderm as occurs in situ (Hampé: Archs Anat Microsc Morph Exp 48:345-378, 1959).We interpret these findings to mean that limb mesoderm which forms the central subset is not merely competent to express in the absence of continuous ectodermal co-culture, a chondrogenic phenotype, but also retains intrinsic, limblike morphogenetic potential to form, regulate, and, to a variable extent, shape a reproducibly specific number of cartilage elements. Because the number of chondrogenic elements that formed in culture appeared stage-specific, a role for the apical ridge in specifying chondrogenic elements prior to its removal is supported. Indeed, our temporal findings correlate closely with the predictable truncation of leg skeletal structures following removal of the apical ridge in ovo, indicating that the endogenous ectodermal influence upon limb mesodermal morphogenesis can be assayed in vitro without the requirement of their continuous co-culture. © 1992 Wiley-Liss, Inc.