Über neue Spektren in der Glimmentladung mit Naphthalindampf

Mit Hilfe einer Methode, die eine systematische Variation der Anregungsbedingungen organischer Substanzen in der positiven Säule gestattet 1 , wurde Naphthalin untersucht, und auch hier, wie früher beim Benzol 2 , eine größere Mannigfaltigkeit der energetischen Vorgänge im Molekül festgestellt, als man es nach den Versuchen der Absorption erwarten sollte.

Neben der aus Absorption und Fluoreszenz bekannten Anregung des Naphthalins im Gebiet von 3100 Ä werden 4 bisher unbekannte Spektren isoliert, die nicht Übergängen zwischen höher angeregten Termzuständen des Moleküls zugeschrieben werden können. Die Träger dieser Spektren lassen sich bisher nicht bestimmen. Man kann nur vermuten, daß es sich um das Leuchten größerer Molekülbruchstücke handelt.

Dasjenige der Spektren, das bei den höchsten Elektronengeschwindigkeiten auftritt ("T-Spektrum"), erweist sich als identisch mit dem beim Benzol diskutierten "T-Spektrum". Sein Träger hat wahrscheinlich die Konfiguration C2HX (mit x = 1, 2 oder 3), weil es unter ähnlichen Bedingungen auch beim Äthylen beobachtet wird.

Die anderen Spektren müssen noch größeren Molekülbruchstücken zugeordnet werden.

Die Intensität der Spektren macht es wahrscheinlich, daß das angeregte Molekül zerfällt und dabei ein angeregtes Bruchstück entsteht.

Außerdem tritt beim Hineinverdampfen von Naphthalin in eine H2-Entladung eine chemisdie Reaktion ein, die zu einem Bruchstück führt, das auch beim Tetrahydronaphthalin erscheint. Da dieses "A-Spektrum" (das 5. neue Spektrum) nicht dem Tetrahydronaphthalinmolekül selbst angehört, muß es sich bei beiden Substanzen um das Leuchten des gleichen Bruchstückes handeln.

Über die Bildung von Hydrazin (NH2-NH2) aus Ammoniak (NH3) in der Glimmentladung

Die Bildung von Hydrazin in einer Ammoniak-Glimmentladung wird quantitativ untersucht, die erhaltenen Werte werden mit entsprechenden Werten der Ozonisator-Entladung verglichen 1, da bisher beim Ozonisator die günstigsten Ausbeuten beobachtet wurden. Gegenüber einer optimalen Ausbeute von 3-4 g Hydrazin pro kWh beim Ozonisator ergeben sich in der Glimmentladung etwa 4mal höhere Werte, nämlich 13 g Hydrazin pro kWh. Außerdem erhöht sich das Verhältnis des gebildeten Hydrazins zu dem durchgeströmten Ammoniak um den Faktor 4. Damit ist zunächst für den Fall des Hydrazins nachgewiesen, daß beim Vergleich mit verschiedenen elektrischen Entladungen die chemische Ausbeute in der Glimmentladung (vor allem in der positiven Säule) am günstigsten liegt.

Es wird gezeigt, daß bei der Bildung von Hydrazin in der Glimmentladung mindestens 5,8% der gesamten Entladungsenergie zur Synthese von Hydrazin aus Ammoniak aufgewandt werden.

Über neue Emissionsbanden bei elektrischer Anregung des Ammoniaks

Bei elektrischer Anregung von Ammoniak unter Drucken bis zu 1 atm wurden im Bereich von 5200 bis 8500 A zwei neue, als „C“- und „D-Spektrum“ bezeichnete Bandensysteme beobachtet. Beide Spektren wurden sowohl im NH3 als auch im ND3 untersucht. Die Isotopieverschiebung ist groß. Für das C-Spektrum deuten die beobachteten Schwingungen auf einen Träger hin, der neben einem oder mehreren H-Atomen mindestens 2 N-Atome enthält.

Beobachtungen von Elementarprozessen an angeregten Molekülen

A method is described which allows to observe only primary processes by elimination of secondary and higher processes. The products formed by dissociation of excited cyclohexane molecules are explained by innermolecular elementary processes. Two reaction schemes are discussed for the formation of the observed C2⁻, C3⁻, and C4⁻hydrocarbons, which follow from the C3 : C3⁻ and C4 : C2⁻cleavage. The experimental results establish these two reaction schemes quantitatively.

The processes for the stabilization of the formed biradicals during cleavage of the cyclohexane ring are of equal probability as it is following from the discussed reaction schemes

Über das Auftreten von gemeinsamen Bruchstücken (mehratomige Radikale?) bei Benzolderivaten in der Glimmentladung

Es wird gezeigt, daß die neuen Spektren, die bei Monoderivaten des Benzols bei Anregung in der positiven Säule einer Glimmentladung beobachtet werden, nicht Übergängen zwischen angeregten Zuständen entsprechen, wie zunächst erwartet, vielmehr handelt es sich hier um das Leuchten von Molekülbruchstücken, deren Bildung eine Eigenschaft der höher angeregten Molekülzustände ist. Die Beweisführung stützt sich auf die Tatsache des Auftretens identischer Spektren bei verschiedenen Substanzen. Da es sich um einen neuen Beobachtungskomplex handelt, dessen Zusammenhang mit den vorliegenden Befunden anderer Untersuchungsmethoden zunächst nicht bekannt ist, kann man im Augenblick nur versuchen, auf Grund der experimentellen Versuche in der Glimmentladung Schlüsse auf die Träger dieser neuen Spektren zu erhalten. So wird mit Hilfe eines umfangreichen Beobachtungsmaterials gezeigt, daß der Träger des „V-Spektrums“ nur eine der Konfigurationen: C6H5; CeH5-C; C6H5-CH oder C6H5-CH2 haben kann.

Über ein Spektrum im Sichtbaren beobachtet bei Acetylen, Äthylen und aromatischen Molekülen(Träger C2 HX; x = 1, 2 oder 3)

Mit der Methode der Variation der Elektronengeschwindigkeiten2 in der positiven Säule einer Glimmentladung wurde bei Benzol3 und Naphthalin4 ein gemeinsames Spektrum, „T-Spektrum“, beobachtet. Im Verlauf weiterer Untersuchungen wurde dieses Spektrum auch noch bei einer Reihe anderer organischer Substanzen festgestellt. Befunde an Äthylen und Acetylen deuten darauf hin, daß dem Träger dieses Spektrums die Konfiguration C2HX zukommt, wobei x zunächst die Werte 0—4 annehmen könnte. Aus der Intensität des Spektrums bei verschiedenen Substanzen sowie aus anderen Gründen ist zu folgern, daß C2(x = 0) und C2H4 (x=4) nicht in Frage kommen dürften. Es wird zunächst vermutet, daß das „T-Spektrum “ einem Übergang von Acetylen oder einem der Radikale C2H oder C2H3 zuzuordnen ist. Vielleicht können Versuche mit deuteriertem und methyliertem Acetylen und Äthylen weitere Aufschlüsse über den Träger des „T-Spektrums“ geben.

Am Ende der Arbeit befindet sich ein Anhang mit den experimentellen Daten dieser Untersuchungsmethode.

Über Diacetylen in der Glimmentladung

Untersuchungen in der positiven Säule einer Glimmentladung mit Diacetylendampf führen zu folgenden Befunden:

1. Das der Absorption in UV entsprechende Emissionsspektrum tritt nicht auf.

2. Im Sichtbaren erscheint ein sehr intensives Bandenspektrum 4673—6500 Å, dessen erste Schwingungsanalyse angegeben wird. Die Schwingungen sind in guter Übereinstimmung mit den Schwingungen des Grundzustandes von Diacetylen (nach Infrarot- und Raman-Untersuchungen). Der angeregte Zustand ist unbekannt. Die diesem Übergang entsprechende Absorption konnte nicht gefunden werden.

Das Spektrum wurde bereits früher3 bei einigen aromatischen Verbindungen sowie bei Äthylen und Acetylen beobachtet und damals als C2HX gedeutet. Nach den jetzigen Befunden muß es sich bei diesen Substanzen um ein Polymerisationsprodukt von C2H-Bruchstücken handeln.

Über den spektroskopischen Nachweis des Benzyl- und des Benzalradikals (C6H5CH2 und C6H5CH)

In der positiven Säule einer Glimmentladung zeigen Benzolderivate bei zusätzlicher Erwärmung des Entladungsrohres (bis ~300°C) neue Spektren, die auf einen schrittweisen Abbau des Substituenten hinweisen. Für Toluol, i-Propylbenzol und tertiäres Butylbenzol wird ein Abbauschema gegeben. Die bisher beobachteten Spektren werden an Hand dieses Schemas diskutiert. Dadurch ergeben sich neue Argumente für die Zuordnung des V- bzw. B-Spektrums zum Benzyl- bzw. Benzalradikal. Beim Spektrum des Benzylradikals wird gezeigt, daß es sich um den Übergang vom tiefsten angeregten Zustand zum Grundzustand handelt.

Chemische Reaktionen in der positiven Säule einer Glimmentladung

Es werden erste Ergebnisse von Untersuchungen über die Reaktionsprodukte in der positiven Säule einer Glimmentladung durch Benzoldampf mitgeteilt. Gaschromatographisch wurden bisher folgende Produkte identifiziert: Diphenyl, Toluol, Äthylbenzol, Phenylacetylen, cis-1-Phenylbutadien-(1.3) und Naphthalin. Daneben wurde in etwa 50-proz. Ausbeute ein Polymerisat gebildet, das in 2 Anteile zerlegt werden konnte: einen benzollöslichen (mittleres Molekulargewicht 708; C/H 1: 0,97) und einen kleineren unlöslichen Anteil. Aus dem benzollöslichen Polymerisat wurde wiederum eine Komponente mit dem Molekulargewicht circa 440, entsprechend etwa der Bruttoformel C32 - 36 H30 - 34 abgetrennt. Die IR-Spektren der Polymerisate weisen auf phenylsubstituierte aliphatische Ketten hin.

Trans-1-Phenylbutadien-(1.3) wurde in der Glimmentladung isomerisiert und das cis-Isomere cyclisierte unter H2 - Abspaltung direkt zu Naphthalin.

Is maternal duplication of 11p15 associated with Silver-Russell syndrome?

BACKGROUND

Silver-Russell syndrome (SRS) is a heterogeneous malformation syndrome characterised by intrauterine and postnatal growth retardation (IUGR, PGR) and dysmorphisms. The basic causes are unknown, however in approximately 10% of patients a maternal uniparental disomy (UPD) of chromosome 7 or chromosomal aberrations can be detected. Four growth retarded children, two with SRS-like features, associated with maternal duplications of 11p15 have been described. Considering the involvement of this genomic region in Beckwith-Wiedemann overgrowth syndrome (BWS), we postulated that some cases of SRS--with an opposite phenotype to BWS--might also be caused by genomic disturbances in 11p15.

METHODS

A total of 46 SRS patients were screened for genomic rearrangements in 11p15 by STR typing and FISH analysis.

RESULTS

Two SRS patients with duplications of maternal 11p material in our study population (n = 46) were detected. In patient SR46, the duplicated region covered at least 9 Mb; FISH analysis revealed a translocation of 11p15 onto 10q. In patient SR90, additional 11p15 material (approximately 5 Mb) was translocated to the short arm of chromosome 15.

CONCLUSIONS

We suggest that diagnostic testing for duplication in 11p15 should be offered to patients with severe IUGR and PGR with clinical signs reminiscent of SRS. SRS is a genetically heterogeneous condition and patients with a maternal duplication of 11p15.5 may form an important subgroup.

White-matter disease in 18q deletion (18q?) syndrome: magnetic resonance spectroscopy indicates demyelination or increased myelin turnover rather than dysmyelination

Proton magnetic resonance spectroscopic data ((1)H-MR spectroscopy) of patients with 18q deletion syndrome have not yet been reported. (1)H-MR spectroscopy, performed in an affected 2-year-old girl with markedly delayed neuromotor development and typical supratentorial white-matter disease (WMD), showed an increase of choline and alpha-glutamate concentrations. Eight months later, simultaneously with clinical improvement, alpha-glutamate had normalised whereas choline remained slightly increased. Active demyelination or increased myelin turnover might contribute to the hitherto unexplained WMD of this rare disorder.

ATPase activity and conformational changes in the regulation of actin

The eukaryotic microfilament system is regulated in part through the nucleotide- and cation-dependent conformation of the actin molecule. In this review, recent literature on the crystal and solution structures of actin and other actin-superfamily proteins is summarized. Furthermore, the structure of the nucleotide binding cleft is discussed in terms of the mechanism of ATP hydrolysis and P(i) release. Two distinct domain movements are suggested to participate in the regulation of actin. (1) High-affinity binding of Mg(2+) to actin induces a rearrangement of side chains in the nucleotide binding site leading to an increased ATPase activity and polymerizability, as well as a rotation of subdomain 2 which is mediated by the hydroxyl of serine-14. (2) Hydrolysis of ATP and subsequent release of inorganic phosphate lead to a butterfly-like opening of the actin molecule brought about by a shearing in the interdomain helix 135-150. These domain rearrangements modulate the interaction of actin with a variety of different proteins, and conversely, protein binding to actin can restrict these conformational changes, with ultimate effects on the assembly state of the microfilament system.

Sound attenuation of polymerizing actin reflects supramolecular structures: viscoelastic properties of actin gels modified by cytochalasin D, profilin and alpha-actinin

Polymerization and depolymerization of cytoskeletal elements maintaining cytoplasmic stiffness are key factors in the control of cell crawling. Rheometry is a significant tool in determining the mechanical properties of the single elements in vitro. Viscoelasticity of gels formed by these polymers strongly depends on both the length and the associations of the filaments (e.g. entanglements, annealings and side-by-side associations). Ultrasound attenuation is related to viscosity, sound velocity and supramolecular structures in the sample. In combination with a small glass fibre (2 mm x 50 microm), serving as a viscosity sensor, an acoustic microscope was used to measure the elasticity and acoustic attenuation of actin solutions. Changes in acoustic attenuation of polymerizing actin by far exceed the values expected from calculations based on changes in viscosity and sound velocity. During the lag-phase of actin polymerization, attenuation slightly decreases, depending on actin concentration. After the half-maximum viscosity is accomplished and elasticity turns into steady state, attenuation distinctly rises. Changes in ultrasound attenuation depend on actin concentration, and they are modulated by the addition of alpha-actinin, cytochalasin D and profilin. Thus absorption and scattering of sound on the polymerization of actin is related to the packing density of the actin net, entanglements and the length of the actin filaments. Shortening of actin filaments by cytochalasin D was also confirmed by electron micrographs and falling-ball viscosimetry. In addition to viscosity and elasticity, the attenuation of sound proved to be a valuable parameter in characterizing actin polymerization and the supramolecular associations of F-actin.

Cloning and characterization of the breakpoint regions of a chromosome 11;18 translocation in a patient with hamartoma of the retinal pigment epithelium

Mutations of various tumor suppressor genes, e.g., PTEN, TSC1, and TSC2, are known to be responsible for different inherited diseases presenting with multiple hamartomas, a benign tumor resembling neoplasia that results from faulty organ development. Combined hamartoma of the retinal pigment epithelium (RPE) and retina is a rare, congenital, focal malformation of the fundus. So far, no disease gene has been associated with this disorder. By molecular analysis of an apparently balanced and reciprocal translocation between the short arms of chromosomes 11 and 18, t(11;18)(p13;p11.31), in a patient with hamartoma of the RPE and retina, we selected PAC clones crossing the breakpoints on both derivative chromosomes 11 and 18. For the overlapping chromosome 11 clone, two EST clusters were identified, suggesting the existence of at least two genes in the breakpoint region. We constructed a PAC contig and showed that at least three exons of a novel gene map to the breakpoint region on chromosome 18. Based on the results of FISH analysis with the PAC clones of this contig, we suggest the occurrence of a complex rearrangement.

Covalent binding of ATPgammaS to the nucleotide-binding site in S14C-actin

We have recently reported on the characterization of beta-actin carrying the mutation S14C in one of the phosphate-binding loops. The present paper describes the attachment of the adenosine 5'-[gamma-thio]-triphosphate (ATPgammaS) to actin containing this mutation. Treatment of S14C-actin with ATPgammaS blocked further nucleotide exchange and raised the thermal stability of the protein, suggesting the formation of a covalent bond between the sulfhydryl on the terminal phosphate of ATPgammaS and cysteine-14 of the mutant actin. The affinity of the derivatized G-actin for DNase I as compared to wild-type ATP-actin was lowered to a similar extent as that of ADP.AlF(4)-actin. The derivatized actin polymerized slower than ATP-actin but faster than ADP-actin. Under these conditions the bound ATPgammaS was hydrolyzed, suggesting the formation of a state corresponding to the transient ADP.P(i)-state. ATPgammaS-actin interacted normally with profilin, whereas the interaction with actin depolymerizing factor (ADF) was disturbed, as judged on the effects of these proteins on actin polymerization.

Mutational analysis of arginine 177 in the nucleotide binding site of beta-actin

Actin ADP-ribosylated at arginine 177 is unable to hydrolyze ATP, and the R177 side chain is in a position similar to that of the catalytically essential lysine 71 in heat shock cognate protein Hsc70, another member of the actin-fold family of proteins. Therefore, actin residue R177 has been implicated in the mechanism of ATP hydrolysis. This paper compares wild-type beta-actin with a mutant in which R177 has been replaced by aspartic acid. The mutant beta-actin was expressed in Saccharomyces cerevisiae and purified by DNase I-affinity chromatography. The mutant protein exhibited a reduced thermal stability and an increased nucleotide exchange rate, suggesting a weakened interdomain connection. The ATPase activity of G-actin and the ATPase activity expressed during polymerization were unaffected by the R177D replacement, showing that this residue is not involved in catalysis. In the presence of polymerizing salts, ATP hydrolysis by both wild-type Mg-beta-actin and the mutant protein preceded filament formation. With the mutant actin, the initial rate of ATP hydrolysis was as high as with wild-type actin, but polymer formation was slower, reached lower steady-state levels, and the polymers formed exhibited much lower viscosity. The critical concentration of polymerization (Acc) of the mutant actin was increased 10-fold as compared to wild-type actin. Filaments formed from the R177D mutant beta-actin bound phalloidin.

Thermal unfolding of G-actin monitored with the DNase I-inhibition assay stabilities of actin isoforms

Actin is one of the proteins that rely on chaperonins for proper folding. This paper shows that the thermal unfolding of G-actin, as studied by CD and ultraviolet difference spectrometry, coincides with a loss in DNase I-inhibiting activity of the protein. Thus, the DNase I inhibition assay should be useful for systematic studies of actin unfolding and refolding. Using this assay, we have investigated how the thermal stability of actin is affected by either Ca2 + or Mg2 + at the high affinity divalent cation binding site, by the concentration of excess nucleotide, and by the nucleotide in different states of phosphorylation (ATP, ADP.Pi, ADP. Vi, ADP.AlF4, ADP.BeFx, and ADP). Actin isoforms from different species were also compared, and the effect of profilin on the thermal stability of actin was studied. We conclude that the thermal unfolding of G-actin is a three-state process, in which an equilibrium exists between native actin with bound nucleotide and an intermediate free of nucleotide. Actins in the Mg-form were less stable than the Ca-forms, and the stability of the different isoforms decreased in the following order: rabbit skeletal muscle alpha-actin = bovine cytoplasmic gamma-actin > yeast actin > cytoplasmic beta-actin. The activation energies for the thermal unfolding reactions were in the range 200-290 kJ.mol- 1, depending on the bound ligands. Generally, the stability of the actin depended on the degree with which the nucleotide contributed to the connectivity between the two domains of the protein.

Mutational analysis of Ser14 and Asp157 in the nucleotide-binding site of beta-actin

This paper compares wild-type and two mutant beta-actins, one in which Ser14 was replaced by a cysteine, and a second in which both Ser14 and Asp157 were exchanged (Ser14-->Cys and Ser14-->Cys, Asp157-->Ala, respectively). Both of these residues are part of invariant sequences in the loops, which bind the ATP phosphates, in the interdomain cleft of actin. The increased nucleotide exchange rate, and the decreased thermal stability and affinity for DNase I seen with the mutant actins indicated that the mutations disturbed the interdomain coupling. Despite this, the two mutant actins retained their ATPase activity. In fact, the mutated actins expressed a significant ATPase activity even in the presence of Ca2+ ions, conditions under which actin normally has a very low ATPase activity. In the presence of Mg2+ ions, the ATPase activity of actin was decreased slightly by the mutations. The mutant actins polymerized as the wild-type protein in the presence of Mg2+ ions, but slower than the wild-type in a K+/Ca2+ milieu. Profilin affected the lag phases and elongation rates during polymerization of the mutant and wild-type actins to the same extent, whereas at steady-state, the concentration of unpolymerized mutant actin appeared to be elevated. Decoration of mutant actin filaments with myosin subfragment 1 appeared to be normal, as did their movement in the low-load motility assay system. Our results show that Ser14 and Asp157 are key residues for interdomain communication, and that hydroxyl and carboxyl groups in positions 14 and 157, respectively, are not necessary for ATP hydrolysis in actin.

Mapping of the gene for X-chromosomal split-hand/split-foot anomaly to Xq26-q26.1

A large inbred kindred from Pakistan in which an isolated type of split-hand/split-foot anomaly is transmitted as an X-chromosomal trait has previously been described. An X/autosomal translocation and an X-chromosomal rearrangement have been excluded by cytogenetic studies. In order to map the gene responsible for this disorder, linkage analysis has been performed by using 14 highly polymorphic DNA markers distributed over the whole X chromosome. Two-point linkage analysis between the disease locus and X-chromosomal marker loci gives maximal lod scores at theta = 0.00 with the loci DXS294 (Zmax = 5.13) and HPRT (Zmax = 4.43), respectively, suggesting that the gene for the X-chromosomal split-hand/split-foot anomaly is localized at Xq26-q26.1.

Chromosomal findings in fetuses with prenatally diagnosed cysts of the choroid plexus

Choroid plexus cysts were diagnosed in 25 out of 823 fetuses with prenatally diagnosed abnormalities (growth retardation/malformations). Among these, 5 revealed a chromosomal disorder (4 cases with trisomy 18 and one case with a translocation trisomy 21). Additional abnormalities, such as growth retardation, holoprosencephaly, hydrocephalus and club foot, were found in 6 out of the 20 fetuses with no chromosomal abnormality. All fetuses with a chromosomal disorder revealed further typical prenatally recognizable abnormalities. Our observation indicates that prenatally diagnosed choroid plexus cysts should be considered as an indication for prenatal chromosomal diagnosis, although the risk of there being an underlying chromosomal disorder is low in cases with no additional abnormalities.

[HLA antigen frequencies in patients with autosomal dominant polycystic kidney degeneration]

20 non-related patients suffering from autosomal dominantly polycystic renal disease were HLA-A, -B, -C and -DR typified and the HLA frequencies were compared with the normal population. Tissue typing was performed using the lymphocytotoxicity test using 180 well-characterized test sera. In contrast to the literature no significant differences were found. However, the value of erythrocytic phosphoglycolate-phosphatase-phenotyping should be checked in the genetic control and consultation.

[The effect of selected drugs on the parameters of conjunctival photoplethysmography]

With a newly developed photoplethysmographical measuring device it is possible to record the conjunctival pulse of the human eye. The device consists of the self-constructed photoplethysmographical amplifier unit, the sucking electrode from silicone hard-rubber with photo-detector and luminescence diode, and a 3-channel recorder (3-NEK). Electrocardiogram and the conjunctival pulse are recorded simultaneously. Parameters that are derived from the curves allow to judge on the circulation in the tissue region investigated. Investigations were carried out in 70 test persons without clinical or other signs of pathological conditions regarding eye or vessels (classified into sex and age groups up to 40 years and over). 133 recordings with six consecutive curve waves were examined. Additionally, the influence of vasoactive drugs on the conjunctival pulse curves was investigated. The topical application of Oculoguttae Tolazolini 2% and Oculoguttae Epinephrini 2% showed no influence compared with the reference curves. Contrary to this, differences were proved after application of Nitrangin liquidum systemically in all parameters tested. The photoplethysmography of the conjunctiva bulbi is a noninvasive running-on method with good reproducibility without troubles for the patient, with an easy performance and only a small time demand. The results qualified the method to test the influence of systemically applied vasoactive drugs.