Showing papers by "University of Göttingen published in 1994"

Cerebrospinal fluid in the diagnosis of multiple sclerosis: a consensus report.

Abstract: The Committee of the European Concerted Action for Multiple Sclerosis (Charcot Foundation) organised five workshops to discuss CSF analytical standards in the diagnosis of multiple sclerosis. This consensus report from 12 European countries summarises the results of those workshops. It is hoped that neurologists will confer with their colleagues in clinical chemistry to arrange the best possible local practice. The most sensitive method for the detection of oligoclonal immunoglobulin bands is isoelectric focusing. The same amounts of IgG in parallel CSF and serum samples are used and oligoclonal bands are revealed with IgG specific antibody staining. All laboratories performing isoelectric focusing should check their technique at least annually using "blind" standards for the five different CSF and serum patterns. Quantitative measurements of IgG production in the CNS are less sensitive than isoelectric focusing. The preferred method for detection of blood-CSF barrier dysfunction is the albumin quotient. The CSF albumin or total protein concentrations are less satisfactory. These results must be interpreted with reference to the age of the patient and the local method of determination. Cells should be counted. The normal value is no more than 4 cells/microliters. Among evolving optional tests, measurement of the combined local synthesis of antibodies against measles, rubella, and/or varicella zoster could represent a significant advance if it offers higher specificity (not sensitivity) for identifying chronic rather than acute inflammation. Other tests that may have useful correlations with clinical indices include those for oligoclonal free light chains, IgM, IgA, or myelin basic protein concentrations.

Experimental inductions of emotional states and their effectiveness: A review

Abstract: Several procedures for the experimental induction of mood states have been developed. This paper reviews nearly 250 studies from the last 10 years which concern mood induction procedures. A classification system is introduced. According to the stimuli used to influence subjects, five groups of mood induction procedures (MIPs) are differentiated. The effectiveness of MIPs is analysed and compared. The Film/Story MIP and the Gift MIP proved to be highly effective in inducing elation. For the induction of depression, the Imagination MIP, the Velten MIP, the Film/Story MIP and the Success/Failure MIP can be recommended.

Patterns of oligodendroglia pathology in multiple sclerosis

Abstract: Patterns of inflammation, demyelination and oligodendrocyte pathology were studied in acute multiple sclerosis and during early and late exacerbations of chronic multiple sclerosis. Cells within lesions were identified by immunocytochemistry with markers for T lymphocytes, macrophages, oligodendro-cytes and astrocytes. In addition, in situ hybridization for proteolipid protein mRNA was used to identify myelinating and myelin supporting oligodendrocytes. Degenerating cells in the lesions were detected by DNA fragmentation in cell nuclei. The inflammatory reaction in all three types of multiple sclerosis lesions was shown to be dominated by T lymphocytes and macrophages. In late chronic multiple sclerosis lesions, a significant increase in the number of immunoglobulin producing plasma cells was found in infiltrates as compared with acute and early multiple sclerosis lesions. In all three types of multiple sclerosis, confluent plaques of demyelination were found to be present. In acute multiple sclerosis, demyelination was found to be associated with extensive destruction of other tissue elements, including oligodendrocytes, astro-Acytes and axons, but even in these destructive lesions a considerable number of oligodendrocytes was preserved and at disposal therefore, for rapid remyelination. During early exacerbations of chronic multiple sclerosis, selective demyelination was associated with almost complete preservation of oligodendrocytes in the majority of cases. Correspondingly, a high number of remyelinating lesions was present at that stage of disease. In lesions developing late after onset of multiple sclerosis, demyelination generally accompanied extensive destruction and loss of oligodendrocytes. In these lesions, remyelination was sparse and restricted to lesional borders. The observed patterns of cell death suggest that in some cases oligodendrocytes, in others myelin sheaths are the primary target of the destructive process. Our data indicate that the type and amount of inflammation, de- and remyelination, and of tissue damage vary between different forms of multiple sclerosis and between different stages of the disease, possibly reflecting different pathogenic mechanisms in a disease spectrum.

Creatine Deficiency in the Brain: A New, Treatable Inborn Error of Metabolism

Abstract: In a patient with extrapyramidal movement disorder and extremely low creatinine concentrations in serum and urine, in vivo proton magnetic resonance spectroscopy disclosed a generalized depletion of creatine in the brain. Oral substitution of arginine, a substrate for creatine synthesis, resulted in an increase of brain guanidinoacetate as the immediate precursor of creatine but did not elevate cerebral creatine levels. In contrast, oral substitution of creatine-monohydrate led to a significant increase of brain creatine, a decrease of brain guanidinoacetate, and a nor-malization of creatinine in serum and urine. Phosphorus magnetic resonance spectroscopy of the brain revealed no detectable creatine-phosphate before oral substitution of creatine and a significant increase afterward. Partial restoration of cerebral creatine concentrations was accompanied by improvement of the patient's neurologic symptoms. This is the first report of a patient with complete creatine deficiency in the brain. Magnetic resonance spectroscopy during arginine and creatine treatment point to an inborn error of creatine biosynthesis at the level of guanidinoacetete-methyltransferase.

Differentiation of endothelial cells: analysis of the constitutive and activated endothelial cell phenotypes.

Abstract: Endothelial cells line the inside of all blood vessels, forming a structurally and functionally heterogeneous population of cells. Their complexity and diversity has long been recognized, yet very little is known about the molecules and regulatory mechanisms that mediate the heterogeneity of different endothelial cell populations. The constitutive organ- and microenvironment-specific phenotype of endothelial cells controls internal body compartmentation, regulating the trafficking of circulating cells to distinct vascular beds. In contrast, surface molecules associated with the activated cytokine-inducible endothelial phenotype play a critical role in pathological conditions including inflammation, tumor angiogenesis, and wound healing. Differentiation of the endothelial cell phenotypes appears to follow similar mechanisms to the differentiation of hematopoietic cells, with the exception that endothelial cells maintain transdifferentiating competence. The present review offers a scheme of endothelial cell differentiation and discusses the possible applications of differentially expressed endothelial cell molecules as targets for directed therapeutic intervention.

Kleider machen Leute: Heck-Reaktion im neuen Gewand†

Abstract: Die von Richard F. Heck Ende der sechziger Jahre entdeckte Palladium-katalysierte Kupplung von Aryl- und Alkenylhalogeniden mit Alkenen hat sich nach gelegentlichem Auf- und Abschwellen des darauf gerichteten Interesses in den letzten sechs Jahren nachhaltig gemausert. Durch geschickte Auswahl der Substrate und sorgfaltige Anpassung der Reaktionsbedingungen gelingen beeindruckende Sequenzen auch unterschiedlicher Reaktionstypen nicht nur nacheinander, sondern vielfach in einem einzigen Verfahrensschritt. Die mittlerweile etablierte Heck-Reaktion – und eine Reihe mit ihr mechanistisch verwandter Palladium-katalysierter Umwandlungen an Aren-, Alken- und Alkinderivaten – bietet ungezahlte Moglichkeiten, elegant und hochkonvergent komplexe Molekule aufzubauen; dabei bereiten Sauerstoff- und Stickstoffatome (mit Einschrankungen auch Schwefel- und Phosphoratome) in den Reaktionen keine Probleme. Das Spektrum der neueren Erfolge beginnt mit den chemo- und regioselektiven Einfachkupplungen hochfunktionalisierter Substrate mit unsymmetrisch mehrfach substituierten Reaktionspartnern. Es reicht allerdings viel weiter uber Kaskadenreaktionen mit Knupfung von drei, vier, funf oder gar acht neuen CC-Bindungen unter Bildung von oligofunktionellen und oligocyclischen Produkten von beeindruckender Molekulkomplexitat bis hin zum enantioselektiven Aufbau von anspruchsvollen Naturstoffmolekulen mit quartaren stereogenen Zentren, wie die Beispiele Crinan, Picrotoxinin, Morphin und viele mehr belegen. Zweifellos last sich schon heute die Heck-Reaktion aus dem Methodenarsenal der praparativen Organischen Chemie nicht mehr wegdenken; abzuwarten bleibt lediglich, wann sie Einzug in ein industrielles Produktionsverfahren halten wird.

Cellular immunodeficiency enhances the progression of human papillomavirus-associated cervical lesions.

Abstract: Most cases of low-grade cervical intraepithelial neoplasia (CIN) associated with oncogenic human papillomavirus (HPV) types regress spontaneously within years. Unknown co-factors seem to be necessary for a progression to malignancy. To determine the possible role of cellular immunodeficiency as such a co-factor in the genesis of genital neoplasia, 48 HIV-infected women and 52 allograft recipients were examined periodically during a 3-year period. Colposcopy, cytology and HPV-DNA typing (ViraType) were performed at each visit. Each cervical lesion was matched prospectively with 2 lesions from immunocompetent controls. In all, 29/100 patients suffered from cervical neoplasms, including 2 advanced cervical cancers and 9 CIN3 lesions. Correlation between grade of lesion and HPV DNA 16/18 was significant. Low-grade lesions among patients progressed more often than among controls and recurrent lesions after destructive treatment were seen more frequently among patients than among controls. All patients with CD4-lymphocyte counts of < 400/microliters or immunosuppression for more than 3 years suffered from progressive lesions. We conclude that malfunction of the cellular immune response following either HIV-induced depletion or iatrogenic inhibition of CD4-lymphocyte activation, enhances the progression of HPV-induced cervical lesions to malignancy.

The excretion of citric and malic acid by proteoid roots of Lupinus albus L.; effects on soil solution concentrations of phosphate, iron, and aluminum in the proteoid rhizosphere in samples of an oxisol and a luvisol

Abstract: Organic acid concentration in the proteoid rhizosphere of White Lupin in different soil samples (Oxisol-Ap = Ox, Luvisol-Ap and Luvisol-C = LA and LC) was determined in order to study the influence of root-released carboxylates on the mobilization of phosphate, aluminum, and iron in the rhizosphere In the LC, organic acids were accumulated as Casalts extractable with water In the proteoid rhizosphere of this soil sample 55 μmol citrate and 8 μmol malate per g soil were found In the Ox, no water extractable organic acids were present However, determination of citrate in the solid phase of this soil by Diffuse Reflectance Infrared Fourier Transform Spectroscopy gave concentrations of 88 and 68 μmol citrate per g soil without and with P application, respectively Displaced soil solution from the proteoid root rhizosphere of the Ox and the LA increased in Fe and Al concentrations from <50 μmol/L (soil from reference pots without plants) to more than 600 μmol Fe+Al/L The concentration of P was increased by a factor of 2 despite of P uptake by the proteoid roots The mobilization of Al, Fe, and P is attributed to ligand exchange of phosphate against citrate and to the solubilization of Al and Fe as carboxylate complexes Die Ausscheidung von Citronen- und Apfelsaure durch Proteoidwurzeln von Lupinus albus L; Wirkung auf die Bodenlosungskonzentrationen an Phosphat, Eisen und Aluminium in der Proteoidrhizosphare in Proben eines Oxisols und einer kalkhaltigen Los-Parabraunerde Um die Mobilisierung von Mineralstoffen durch Pflanzen zu studieren, wurde in einem Gefasversuch mit Proben eines Oxisols (Ox), sowie dem Ap (LA) und dem kalkhaltigen C-Horizont (LC) einer Los-Parabraunerde die Konzentration organischer Sauren in der Rhizosphare der Proteoidwurzeln von Weiser Lupine in Beziehung zur Loslichkeit von Phosphat, Eisen und Aluminium untersucht In der Proteoidrhizosphare von LC lagen 55 μmol Citrat und 8 μmol Malat pro g Boden in wasserextrahierbarer Form als Ca-Salz vor In dem Ox (pH 55) waren organische Sauren dagegen nicht in wasserloslicher Form nachweisbar DRIFT-Spektroskopie, durch die organische Sauren ohne vorherige Abtrennung von der mineralischen Phase erfasbar sind, zeigte in dem Ox-Proteoidboden Citratgehalte von 88 μmol/g Boden ohne P-Dungung und 68 μmol/g Boden mit P-Dungung an Die Bodenlosungen der Proteoidrhizosphare enthielten in dem Ox und dem LA jeweils mehr als 600 μmol Fe+Al/L im Gegensatz zu weniger als 50 μmol/L im unbepflanzten Boden Die P-Konzentration der Bodenlosung war in der Proteoidrhizosphare um den Faktor 2 hoher als im unbepflanzten Boden, obwohl die Pflanzen P entzogen hatten Es wird angenommen, das die Erhohung der Loslichkeit auf dem Ligandenaustausch von Phosphat gegen Citrat und der Bildung von Al- und Fe-Carboxylatkomplexen beruht

Cytokine mRNA levels in mononuclear blood cells from patients with multiple sclerosis

Abstract: We determined the cytokine messenger RNA (mRNA) expression pattern of blood mononuclear cells in 45 patients with the relapsing-remitting form of MS and 32 patients with other neurologic diseases. Using a semiquantitative polymerase chain reaction method, we detected significantly higher levels of tumor necrosis factor-alpha and lymphotoxin mRNA in patients with relapsing compared to those with stable disease (p < 0.001), but transforming growth factor-beta and interleukin-10 mRNA expressions were higher in patients with stable disease.

Long-term effects of two different ventilatory modes on oxygenation in acute lung injury. Comparison of airway pressure release ventilation and volume-controlled inverse ratio ventilation.

Abstract: A total of 18 patients with acute lung injury (ALI) were sequentially ventilated with two different modes of mechanical ventilation, each applied for a period of 24 h: (1) volume-controlled inverse ratio ventilation (VC-IRV), (2) airway pressure release ventilation (APRV). The individual sequence of both ventilatory modes was randomized. Ventilatory minute volume was adjusted for a PaCO2 of 35 to 45 mm Hg at the beginning of the study during the first ventilatory mode and then kept constant within preset limits. Hemodynamic variables were stable and similar during the 24-h periods of VC-IRV and APRV as well. Despite the lower sedation and spontaneous breathing during APRV, oxygen uptake was similar during both ventilatory modes. During the 24-h period of VC-IRV there was no relevant change of either airway pressures, alveolo-arterial O2 tension difference (AaDO2)/fraction of inspired oxygen (FIO2) or venous admixture. In contrast, peak airway pressures (Pawmax) during APRV were significantly lower (about ...

Oligodendrocytes in the early course of multiple sclerosis

Abstract: The neuropathology of demyelinating lesions in multiple sclerosis was studied in specimens obtained by diagnostic needle biopsy during early stages of the disease. The lesions were characterized by a chronic inflammatory reaction dominated by lymphocytes and macrophages, plaque-like demyelination, and astroglial sclerosis. Oligodendrocytes within the lesions were studied by immunocytochemistry using antibodies against various myelin and oligodendroglia components. The expression of messenger RNA for proteolipid protein was determined by in situ hybridization. Our studies revealed that myelin-oligodendrocyte glycoprotein is a sensitive and reliable marker for identification of oligodendrocytes in demyelinated plaques. The results suggest that in the early course of the disease in some patients, oligodendrocytes may largely be preserved, whereas in others oligodendroglial loss is pronounced. Loss of oligodendrocytes was only marginally related to the stage of demyelinating activity within the lesions. These findings indicate that the pathogenesis of demyelination may vary within different multiple sclerosis patients.

Bedside assessment of intravascular volume status in patients undergoing coronary bypass surgery.

Abstract: BACKGROUND Management of intravascular volume is crucial in patients after cardiopulmonary bypass as myocardial dysfunction is common. The purpose of this study was to validate a novel bedside technique for real-time assessment of intravascular volumes. METHODS Eleven patients undergoing cardiopulmonary bypass were studied. In addition to standard monitors, a fiberoptic thermistor catheter was placed in the descending aorta and central venous injections of 10 ml ice-cold indocyanine green dye were performed. Total blood volume was measured by a standard in vitro technique. Circulating and central blood volume were calculated by using cardiac output, mean transit times, and a newly developed recursive convolution algorithm that models recirculation. Measurements were performed after induction of anesthesia and at 1, 6, and 24 h after surgery. RESULTS A two-compartment model of the circulation was required for adequate fit of the data. We found a significant correlation between total and circulating blood volumes (r = 0.87). One hour after surgery, central blood volume was decreased by 10% (P < 0.05). At 6 and 24 h after surgery, circulating blood volumes were significantly increased by 29% and 20%, respectively (P < 0.01), although central blood volume was similar to control values. Before surgery stroke volume index correlated with circulating blood volume (r = 0.87) but not with pulmonary capillary wedge and central venous pressures. CONCLUSIONS This study shows that bedside determinations of intravascular blood volumes are feasible and that these measurements are more indicative of intravascular volume status than are either pulmonary capillary wedge or central venous pressures in the post-cardiopulmonary bypass period. Our data also demonstrate that despite a normal central blood volume both circulating and total blood volume are significantly increased in the immediate post-cardiopulmonary bypass period.

Ion Channels in the Xylem Parenchyma of Barley Roots. A Procedure to Isolate Protoplasts from This Tissue and a Patch-Clamp Exploration of Salt Passageways into Xylem Vessels.

Abstract: To identify mechanisms for the simultaneous release of anions and cations into the xylem sap in roots, we investigated voltage-dependent ion conductances in the plasmalemma of xylem parenchyma cells. We applied the patch-clamp technique to protoplasts isolated from the xylem parenchyma by differential enzymic digestion of steles of barley roots (Hordeum vulgare L. cv Apex). In the whole-cell configuration, three types of cation-selective rectifiers could be identified: (a) one activated at membrane potentials above about -50 mV; (b) a second type of outward current appeared at membrane potentials above +20 to +40 mV; (c) below a membrane potential of approximately -110 mV, an inward rectifier could be distinguished. In addition, an anion-specific conductance manifested itself in single-channel activity in a voltage range extending from about -100 to +30 mV, with remarkably slow gating. In excised patches, K+ channels activated at hyperpolarization as well as at depolarization. We suggest that salt is released from the xylem parenchyma into the xylem apoplast by simultaneous flow of cations and anions through channels, following electrochemical gradients set up by the ion uptake processes in the cortex and, possibly, the release and reabsorption of ions on their way to the xylem.

Mouse cortical cells lacking cellular PrP survive in culture with a neurotoxic PrP fragment.

Abstract: To elucidate whether the neurotoxic effect of a prion protein fragment (PrP106-126) is in some way mediated by the cellular isoform of the prion protein (PrPC), dissociated cortical cell cultures were prepared from mice in which the PrP gene had been disrupted (PrP0/0 mice). Cell survival after 10 days in culture was tested with an MTT assay. PrP106-126 applied every second day for 10 days in cultures from normal mice resulted in the death of 34% more cells than in untreated cells. When PrP106-126 was applied to cultures from mice lacking PrPC expression, survival was equal to or greater than that of untreated control cells. These results support the notion that expression of PrPC is required for the neurotoxic effect of PrP106-126.

Post-translational alterations in transmembrane topology of the hepatitis B virus large envelope protein.

Abstract: The preS domain at the N-terminus of the large envelope protein (LHBs) of the hepatitis B virus is involved in (i) envelopment of viral nucleocapsids and (ii) binding to the host cell. While the first function suggests a cytosolic location of the preS domain during virion assembly, the function as an attachment site requires its translocation across the lipid bilayer and final exposure on the virion surface. We compared the transmembrane topology of newly synthesized LHBs in the endoplasmic reticulum (ER) membrane with its topology in the envelope of secreted virions. Protease sensitivity and the absence of glycosylation suggest that the entire preS domain of newly synthesized LHBs remains at the cytosolic side of ER vesicles. However, virions secreted from transfected cell cultures or isolated from the blood of persistent virus carriers expose antibody binding sites and proteolytic cleavage sites of the preS domain at their surface in approximately half of the LHBs molecules. Thus, preS domains appear to be transported across the viral lipid barrier by a novel post-translational translocation mechanism to fulfil a dual function in virion assembly and attachment to the host cell.

Combined nickel-cobalt-cadmium resistance encoded by the ncc locus of Alcaligenes xylosoxidans 31A.

Abstract: The nickel-cobalt-cadmium resistance genes carried by plasmid pTOM9 of Alcaligenes xylosoxidans 31A are located on a 14.5-kb BamHI fragment. By random Tn5 insertion mutagenesis, the fragment was shown to contain two distinct nickel resistance loci, ncc and nre. The ncc locus causes a high-level combined nickel, cobalt, and cadmium resistance in strain AE104, which is a cured derivative of the metal-resistant bacterium Alcaligenes eutrophus CH34. ncc is not expressed in Escherichia coli. The nre locus causes low-level nickel resistance in both Alcaligenes and E. coli strains. The nucleotide sequence of the ncc locus revealed seven open reading frames designated nccYXHCBAN. The corresponding predicted proteins share strong similarities with proteins encoded by the metal resistance loci cnr (cnrYXHCBA) and czc (czcRCBAD) of A. eutrophus CH34. When different DNA fragments carrying ncc genes were heterologously expressed under the control of the bacteriophage T7 promoter, five protein bands representing NccA (116 kDa), NccB (40 kDa), NccC (46 kDa), NccN (23.5 kDa), and NccX (16.5 kDa) were detected.

Effect of anaesthesia on the cytokine responses to abdominal surgery

Abstract: Plasma concentrations of interleukinsf particularly IL-6, increase after trauma and surgery. We have undertaken this study to see if the choice of anaesthetic directly or indirectly influences cytokine release. Twenty women (ASA l-ll, aged 26-60 yr) undergoing elective hysterectomy for non-malignant disease were allocated randomly to receive either inhalation anaesthesia with isoflurane and nitrous oxide (group 1), or total i.v. anaesthesia with alfentanii and propofol (group 2). Blood samples for measurement of interleukins IL-1β and IL-βand cortisol and prolactin concentrations were obtained at intervals from before induction to 6 h after surgery. IL- 1β concentrations did not change during the study. IL-6 increased significantly in both groups (P −1 vs 46 (0-220) pgml −1 ) (P

Trap-nesting bees and wasps colonizing set-aside fields: succession and body size, management by cutting and sowing

Abstract: Trap-nesting bees and wasps (Hymenoptera Aculeata) colonizing crop and fallow fields in an agricultural landscape were studied using 20 sown fields (pea, barley, rye, clover-grass mixtures, Phacelia tanacetifolia) and 20 fields with naturally developed vegetation (1- and 2-year old fields, both mown and unmown, and old meadows) Fourteen species of Apoidea, 4 of Sphecidae, 1 of Eumenidae and 4 of parasitoids were reared from reed nests exposed in these 40 fields of 10 field-types Fields with naturally developed vegetation had twice as many species as sown fields, due to the distribution pattern of the 14 bee species, whereas the 9 predatory species (wasps and parasitoids) showed a rather uniform distribution None of the trap-nesting bees were found in Phacelia fields, despite contrasting expectations of beekeepers Old meadows showed a particularly high abundance and species richness, since only 10% of all traps were exposed, but 32% of all bee nests were sampled in old meadows, including 4 bee species that were not found elsewhere Accordingly, species richness of fields with naturally developed vegetation showed a significant increase with age Variability in Hymenoptera species numbers could be explained by corresponding differences in plant species numbers The alternative hypothesis that field size or field connectivity influenced species richness was not supported Habitats with great floral diversity appeared to offer better and richer food resources for the flower-visiting bees, whereas food availability apparently did not influence predatory wasps The bees Osmia caerulescens and Megachile versicolor that had colonized early-successional fields took twice as long to provision cells as those that colonized late-successional meadows characterized by a greater plant species richness In contrast, the eumenid wasp Ancistrocerus gazella took a similar period of time to provision cells in both field types In addition, bee and wasp species of plant-species-poor fields were on average significantly larger than those of plant-species-rich fields Thus, body size appeared to be a good predictor of colonization ability Management by cutting greatly increased plant species richness in early-successional set-aside fields and thus doubled species richness of bees Cutting of early-successional habitats can be expected to benefit insects and plants in general, whereas older grassland should show the greatest insect diversity when both mown and unmown parts are present

Frechet differentiability of boundary integral operators in inverse acoustic scattering

Abstract: Using integral equation methods to solve the time-harmonic acoustic scattering problem with Dirichlet boundary conditions, it is possible to reduce the solution of the scattering problem to the solution of a boundary integral equation of the second kind. We show the Frechet differentiability of the boundary integral operators which occur. We then use this to prove the Frechet differentiability of the scattered field with respect to the boundary. Finally we characterize the Frechet derivative of the scattered field by a boundary value problem with Dirichlet conditions, in an analogous way to that used by Firsch.

Expression cloning of a gibberellin 20-oxidase, a multifunctional enzyme involved in gibberellin biosynthesis

Abstract: In the biosynthetic pathway to the gibberellins (GAs), carbon-20 is removed by oxidation to give the C19-GAs, which include the biologically active plant hormones. We report the isolation of a cDNA clone encoding a GA 20-oxidase [gibberellin, 2-oxoglutarate:oxygen oxidoreductase (20-hydroxylating, oxidizing) EC 1.14.11.-] by screening a cDNA library from developing cotyledons of pumpkin (Cucurbita maxima L.) for expression of this enzyme. When mRNA from either the cotyledons or the endosperm was translated in vitro using rabbit reticulocyte lysates, the products contained GA12 20-oxidase activity. A polyclonal antiserum was raised against the amino acid sequence of a peptide released by tryptic digestion of purified GA 20-oxidase from the endosperm. A cDNA expression library in lambda gt11 was prepared from cotyledon mRNA and screened with the antiserum. The identity of positive clones was confirmed by the demonstration of GA12 20-oxidase activity in single bacteriophage plaques. Recombinant protein from a selected clone catalyzed the three-step conversions of GA12 to GA25 and of GA53 to GA17, as well as the formation of the C19-GAs, GA1, GA9, and GA20, from their respective aldehyde precursors, GA23, GA24, and GA19. The nucleotide sequence of the cDNA insert contains an open reading frame of 1158 nt encoding a protein of 386 amino acid residues. The predicted M(r) (43,321) and pI (5.3) are similar to those determined experimentally for the native GA 20-oxidase. Furthermore, the derived amino acid sequence includes sequences obtained from the N terminus and two tryptic peptides from the native enzyme. It also contains regions that are highly conserved in a group of non-heme Fe-containing dioxygenases.

Causality problems for Fermi's two-atom system

Abstract: Let [ital A] and [ital B] be two atoms or, more generally, a source'' and a detector'' separated by some distance [ital R]. At [ital t]=0[ital A] is in an excited state, [ital B] in its ground state, and no photons are present. A theorem is proved that in contrast to Einstein causality and finite signal velocity the excitation probability of [ital B] is nonzero immediately after [ital t]=0. Implications are discussed.

Molecular structure and chromosomal mapping of the human homolog of the agouti gene.

Abstract: The agouti (a) locus in mouse chromosome 2 normally regulates coat color pigmentation. The mouse agouti gene was recently cloned and shown to encode a distinctive 131-amino acid protein with a consensus signal peptide. Here we describe the cloning of the human homolog of the mouse agouti gene using an interspecies DNA-hybridization approach. Sequence analysis revealed that the coding region of the human agouti gene is 85% identical to the mouse gene and has the potential to encode a protein of 132 amino acids with a consensus signal peptide. Chromosomal assignment using somatic-cell-hybrid mapping panels and fluorescence in situ hybridization demonstrated that the human agouti gene maps to chromosome band 20q11.2. This result revealed that the human agouti gene is closely linked to several traits, including a locus called MODY (for maturity onset diabetes of the young) and another region that is associated with the development of myeloid leukemia. Initial expression studies with RNA from several adult human tissues showed that the human agouti gene is expressed in adipose tissue and testis.