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Showing papers by "University of Göttingen published in 1995"


Journal ArticleDOI
TL;DR: A new class of positive definite and compactly supported radial functions which consist of a univariate polynomial within their support is constructed, it is proved that they are of minimal degree and unique up to a constant factor.
Abstract: We construct a new class of positive definite and compactly supported radial functions which consist of a univariate polynomial within their support. For given smoothness and space dimension it is proved that they are of minimal degree and unique up to a constant factor. Finally, we establish connections between already known functions of this kind.

2,495 citations


Journal ArticleDOI
TL;DR: An overview of the diversity of biosynthetic polyhydroxyalkanoic acids and the importance of bacterial anabolism and catabolism, which provide the coenzyme A thioesters of the respective hydroxyalkanoing acids as substrates to these PHA synthases, is emphasized.
Abstract: An overview is provided on the diversity of biosynthetic polyhydroxyalkanoic acids, and all hitherto known constituents of these microbial storage compounds are listed. The occurrence of 91 different hydroxyalkanoic acids reflects the low substrate specificity of polyhydroxyalkanoic acid synthases which are the key enzymes of polyhydroxyalkanoic acid biosynthesis. In addition, the importance of bacterial anabolism and catabolism, which provide the coenzyme A thioesters of the respective hydroxyalkanoic acids as substrates to these PHA synthases, is emphasized.

1,103 citations


Journal ArticleDOI
TL;DR: The Heck reaction has been a topic of fluctuating interest; however, in the last six years activity in this area has flourished as discussed by the authors, leading to impressive sequences consisting of even different reaction types that occur not only in a consecutive mode, but also in a single operation.
Abstract: The palladium-catalyzed coupling of haloarenes and haloalkenes with alkenes, which was discovered by Richard F. Heck in the late sixties, has been a topic of fluctuating interest; however, in the last six years activity in this area has flourished. Careful choice of substrates and skillful tailoring of reaction conditions lead to impressive sequences consisting of even different reaction types that occur not only in a consecutive mode, but also in a single operation. The wellestablished Heck reaction, together with other mechanistically related palladiumcatalyzed transformations with arene, alkene, and alkyne derivatives, opens the door to a tremendous variety of elegant and highly convergent routes to structurally complex molecules. The reaction is not disturbed by heteroatoms such as oxygen and nitrogen (nor by sulfur and phosphorus with some limitations). The spectrum of recent achievements starts with a range of chemoselective and regioselective monocouplings of highly functionalized substrates with unsymmetrical and multisubstituted reaction partners. Other advances include cascade reactions in which three, four, five, and even eight new CC bonds are formed to yield oligofunctional and oligocyclic products with impressive molecular complexity. Even the enantioselective construction of complex natural products with quaternary stereocenters has been achieved with Heck reactions in key steps, as exemplified by the synthesis of crinan, picrotoxinin, and morphine. Today, the Heck reaction is indispensible in the arsenal of synthetic methods available to organic chemists. Certainly it is only a matter of time before the Heck reaction is applied in industrial syntheses.

974 citations


Journal ArticleDOI
TL;DR: This chapter considers an improved encoding method where the information signal is injected into the dynamical system of the transmitter and highlights how to design in a systematic way high-dimensional synchronized systems that may be used for efficient hyperchaotic encoding of information.
Abstract: A general approach for constructing chaotic synchronized dynamical systems is discussed that is based on a decomposition of given systems into active and passive parts. As a possible application the chapter considers an improved encoding method where the information signal is injected into the dynamical system of the transmitter. Furthermore, it highlights how to design in a systematic way high-dimensional synchronized systems that may be used for efficient hyperchaotic encoding of information. Synchronization of periodic signals is a well-known phenomenon in physics, engineering, and many other scientific disciplines.

885 citations


Journal ArticleDOI
08 Jun 1995-Nature
TL;DR: Synthetic synapsins are not required for neurite outgrowth, synaptogenesis or the basic mechanics of synaptic vesicle traffic, but are essential for accelerating this traffic during repetitive stimulation.
Abstract: Synaptic vesicles are coated by synapsins, phosphoproteins that account for 9% of the vesicle protein. To analyse the functions of these proteins, we have studied knockout mice lacking either synapsin I, synapsin II, or both. Mice lacking synapsins are viable and fertile with no gross anatomical abnormalities, but experience seizures with a frequency proportional to the number of mutant alleles. Synapsin-II and double knockouts, but not synapsin-I knockouts, exhibit decreased post-tetanic potentiation and severe synaptic depression upon repetitive stimulation. Intrinsic synaptic-vesicle membrane proteins, but not peripheral membrane proteins or other synaptic proteins, are slightly decreased in individual knockouts and more severely reduced in double knockouts, as is the number of synaptic vesicles. Thus synapsins are not required for neurite outgrowth, synaptogenesis or the basic mechanics of synaptic vesicle traffic, but are essential for accelerating this traffic during repetitive stimulation. The phenotype of the synapsin knockouts could be explained either by deficient recruitment of synaptic vesicles to the active zone, or by impaired maturation of vesicles at the active zone, both of which could lead to a secondary destabilization of synaptic vesicles.

701 citations


Journal ArticleDOI
TL;DR: A variation of the Narcowich-Ward theory of upper bounds on the norm of the inverse of the interpolation matrix is presented in order to handle the whole set of radial basis functions that are currently in use.
Abstract: For interpolation of scattered multivariate data by radial basis functions, an "uncertainty relation" between the attainable error and the condition of the interpolation matrices is proven. It states that the error and the condition number cannot both be kept small. Bounds on the Lebesgue constants are obtained as a byproduct. A variation of the Narcowich-Ward theory of upper bounds on the norm of the inverse of the interpolation matrix is presented in order to handle the whole set of radial basis functions that are currently in use.

628 citations


Journal ArticleDOI
TL;DR: Findings indicate a differentiated pattern of macrophage activation in MS lesions and allow the staging of demyelinating lesions in routinely fixed and paraffin‐embedded tissue.
Abstract: Monocyte/macrophage differentiation was studied in biopsy samples of multiple sclerosis (MS) lesions obtained in the early course of the disease. Macrophages were identified by immunocytochemistry using a panel of antibodies recognizing different macrophage-activation antigens. The number of cells stained with each antibody was related to the demyelinating activity of the lesions as detected by the presence of myelin degradation products. The pan-macrophage marker Ki-M1P revealed the highest numbers of macrophages in early and late active lesions. Lower numbers were encountered in inactive, demyelinated, or remyelinated lesions. The acute stage inflammatory macrophage markers MRP14 and 27E10 were expressed in either only early active (MRP14) or early and late active (27E10) lesions, thus allowing the identification of actively demyelinating lesions. The chronic stage inflammatory macrophage marker 25F9, in contrast, showed increasing expression with decreasing lesional activity. These findings indicate a differentiated pattern of macrophage activation in MS lesions and allow the staging of demyelinating lesions in routinely fixed and paraffin-embedded tissue.

478 citations


Journal ArticleDOI
TL;DR: The need to investigate factors involved in the maintenance of intrusive traumatic recollections is discussed, suggesting that the idiosyncratic meaning of the intrusive recollections predicts the distress caused by them, and the degree to which the individual engages in strategies to control the intrusions.
Abstract: Intrusive recollections are very common immediately after traumatic events and are considered necessary aspects of emotional processing. However, if these intrusive recollections persist over a long time, they are linked to long-term psychiatric disorder, especially Posttraumatic Stress Disorder (PTSD). This paper discusses the need to investigate factors involved in the maintenance of intrusive traumatic recollections. It is suggested that the idiosyncratic meaning of the intrusive recollections predicts the distress caused by them, and the degree to which the individual engages in strategies to control the intrusions. These control strategies maintain the intrusive recollections by preventing a change in the meaning of the trauma and of the traumatic memories. It is further suggested that what is needed is a comprehensive assessment of the processes that prevent change in meaning, going beyond the assessment of avoidance. In particular, safety behaviours, dissociation and numbing, suppression of memories and thoughts about trauma, rumination, activation of other emotions such as anger and guilt and corresponding cognitions, and selective information processing (attentional and memory biases) may be involved in the maintenance of intrusive recollections. Preliminary data supporting these suggestions from studies of individuals involved in road traffic accidents and survivors of child sexual abuse are described.

460 citations


Journal ArticleDOI
TL;DR: It is suggested, that vital functions of cathepsin D are exerted by limited proteolysis of proteins regulating cell growth and/or tissue homeostasis, while its contribution to bulk proteolytic in lysosomes appears to be non‐critical.
Abstract: Mice deficient for the major lysosomal aspartic proteinase cathepsin D, generated by gene targeting, develop normally during the first 2 weeks, stop thriving in the third week and die in a state of anorexia at day 26 +/- 1. An atrophy of the ileal mucosa first observed in the third week progresses towards widespread intestinal necroses accompanied by thromboemboli. Thymus and spleen undergo massive destruction with fulminant loss of T and B cells. Lysosomal bulk proteolysis is maintained. These results suggest, that vital functions of cathepsin D are exerted by limited proteolysis of proteins regulating cell growth and/or tissue homeostasis, while its contribution to bulk proteolysis in lysosomes appears to be non-critical.

432 citations


Journal ArticleDOI
TL;DR: Neuropathological diagnostic criteria for Creutzfeldt‐Jakob disease (CJD) and other human transmissible spongiform encephalopathies (prion diseases) are proposed.
Abstract: Neuropathological diagnostic criteria for Creutzfeldt-Jakob disease (CJD) and other human transmissible spongiform encephalopathies (prion diseases) are proposed for the following disease entities: CJD - sporadic, iatrogenic (recognised risk) or familial (same disease in 1st degree relative): spongiform encephalopathy in cerebral and/or cerebellar cortex and/or subcortical grey matter; or encephalopathy with prion protein (PrP) immunoreactivity (plaque and/or diffuse synaptic and/or patchy/perivacuolar types). Gerstmann-Straussler-Scheinker disease (GSS) (in family with dominantly inherited progressive ataxia and/or dementia): encephalo(myelo)pathy with multicentric PrP plaques. Familial fatal insomnia (FFI) (in member of a family with PRNP178 mutation): thalamic degeneration, variable spongiform change in cerebrum. Kuru (in the Fore population). Without PrP data, the crucial feature is the spongiform change accompanied by neuronal loss and gliosis. This spongiform change is characterised by diffuse or focally clustered small round or oval vacuoles in the neuropil of the deep cortical layers, cerebellar cortex or subcortical grey matter, which might become confluent. Spongiform change should not be confused with non-specific spongiosis. This includes status spongiosus (''spongiform state''), comprising irregular cavities in gliotic neuropil following extensive neuronal (including also lesions of ''burnt-out'' ''spongy'' changes in brain oedema and metabolic encephalopathies, and artefacts such as superficial cortical, perineuronal, or perivascular vacuolation; focal changes indistinguishable from spongiform change may occur in some cases of Alzheimer's and diffuse Lewy body diseases. Very rare cases might not be diagnosed by these criteria. Then confirmation must be sought by additional techniques such as PrP immunoblotting, preparations for electron microscopic examination of scrapie associated fibrils (SAF), molecular biologic studies, or experimental transmission.

409 citations


Journal ArticleDOI
28 Jul 1995-Cell
TL;DR: Structural analysis of two catalytically active sulfatases revealed that a cysteine residue that is predicted from the cDNA sequence and conserved among all known sulfatased is replaced by a 2-amino-3-oxopropionic acid residue, while in sulfatase derived from MSD cells, this cysteined residue is retained.

Journal ArticleDOI
TL;DR: It is essential to begin studying the effects of increased CO(2), O(3) and UV-B (and other climate change factors) on plant diseases, given the importance of plant diseases in world food and fiber production.

Journal ArticleDOI
TL;DR: Variations in cytokine mRNA expression in blood mononuclear cells are correlated with disease activity in relapsing‐remitting multiple sclerosis and may be a valuable parameter to monitor the immunological status of patients in future clinical trials.
Abstract: We determined the cytokine messenger RNA (mRNA) expression pattern of blood mononuclear cells in 29 patients with relapsing-remitting multiple sclerosis every 4 weeks over a period of 12 months. During this period 27 relapses occurred in 14 patients (48%). Progression of disease activity as assessed by the occurrence of new lesions on nonenhancing T2-weighted magnetic resonance images of the head was detected in 12 (48%) of 25 patients. Using a semiquantitative polymerase chain reaction we demonstrated significant increases in tumor necrosis factor-alpha mRNA expression in peripheral blood mononuclear cells prior to a relapse. In 24 (85%) of 27 relapses increased tumor necrosis factor-alpha mRNA expression preceded clinical symptoms by 4 weeks. A similar pattern was observed for lymphotoxin mRNA expression. At the same time, transforming growth factor-beta and interleukin-10 mRNA levels declined. Fluctuations in the mRNA expression of tumor necrosis factor-alpha were also observed in 6 patients with stable disease who had active magnetic resonance scans on follow-up. No correlation of disease activity was observed with interleukin-1 beta, -4, or -6, inferferon gamma or endothelin-1 mRNA expression. From these data it can be concluded that variations in cytokine mRNA expression in blood mononuclear cells are correlated with disease activity in relapsing-remitting multiple sclerosis. It may be a valuable parameter to monitor the immunological status of patients in future clinical trials.


Journal ArticleDOI
TL;DR: The new Panic and Agoraphobia Scale (P&A) was developed to assess the degree of severity of these disorders after a diagnosis has been made according to the criteria of the DSM-III-R/IV or the ICD-10.
Abstract: Despite the plethora of rating scales for anxiety disorders and agoraphobia, a qualified scale for assessing the severity of panic disorder and agoraphobia (PDA) is still lacking. The new Panic and Agoraphobia Scale (P&A) is presented in this paper. It was developed to assess the degree of severity of these disorders after a diagnosis has been made according to the criteria of the DSM-III-R/IV or the ICD-10. The P&A was specially developed for use in clinical drug trials. Factors which impair the quality of life in panic disorder and agoraphobia patients (panic attacks, phobic avoidance, anticipatory anxiety, impairment in social relationships and work, assumption of somatic disease) were considered in the development of this scale so that the efficacy of a certain drug therapy on each of these factors can be assessed separately. Both an observer rating and a self-rating with matching items are available. The observer rating only takes about 10 minutes to complete. Translation into many European languages is planned so that it can be used in multicentre trials. Satisfactory results of item analysis, inter-rater reliability, objectivity, external validity and factor structure are presented. The P&A should be a useful tool for assessing the severity of PDA and may solve some of the methodological problems that have arisen in former PDA studies.

Journal ArticleDOI
TL;DR: In this article, a compilation and analysis of O-isotope data for Neogene volcanic rocks worldwide was performed, showing that the Earth's upper mantle is heterogeneous with respect to its O-Isotope composition, and that both low 18O and high 18O reservoirs have contributed to basalt petrogenesis.
Abstract: Based upon a compilation and analysis of O-isotope data for Neogene volcanic rocks worldwide, the δ18O variation for 743 basalts (historic lavas, submarine glasses, and lavas with <0.75 wt% H2O) is +2.9 to +11.4‰. Mid-ocean-ridge basalt (MORB) has a uniform O-isotope composition with δ180=+5.7±0.2‰. Basalts erupted in different tectonic settings have mean 18O/16O ratios that are both lower and higher than MORB, with continental basalts enriched in 18O by ca. 1‰ over oceanic basalts. The δ18O range for the subset of 88 basalts with Mg# [100·Mg(Mg+Fe2+)] 75–68, considered to be unmodified primary mantle partial melts, is +3.6 to +8.7‰. These features are a clear indication that: (1) the Earth's upper mantle is heterogeneous with respect to its O-isotope composition; (2) that both low-18O and high-18O reservoirs have contributed to basalt petrogenesis. Large-ion lithophile element-enriched basalts associated with subduction at convergent plate margins are slightly enriched in 18O, a characteristic that is considered to be an intrinsic feature of the subduction process. Intraplate oceanic and continental basalts have highly variable 18O/16O ratios, with individual localities displaying δ18O ranges in excess of 1.5 to 2‰. Systematic co-variations between O-, Sr-, Nd-, and Pb-isotope ratios reflect the same principal intramantle end-member isotopic components (DMM, HIMU, EM-I, EM-II) deduced from radiogenic isotope considerations and, therefore, imply that a common process is responsible for the origin of upper mantle stable and radiogenic isotope heterogeneity, namely the recycling of lithospheric material into the mantle.

Journal ArticleDOI
31 Mar 1995-Science
TL;DR: A forward model of the inner core based on the predicted elastic constants and the assumption that the innercore consists of a nearly perfectly aligned aggregate of hcp crystals shows good agreement with seismic travel time anomalies that have been attributed to inner core anisotropy.
Abstract: A first principles theoretical approach shows that, at the density of the inner core, both hexagonal [hexagonal close-packed (hcp)] and cubic [face-centered-cubic (fcc)] phases of iron are substantially elastically anisotropic. A forward model of the inner core based on the predicted elastic constants and the assumption that the inner core consists of a nearly perfectly aligned aggregate of hcp crystals shows good agreement with seismic travel time anomalies that have been attributed to inner core anisotropy. A cylindrically averaged aggregate of fcc crystals disagrees with the seismic observations.

Journal ArticleDOI
TL;DR: A 5.0-kbp genomic EcoRI restriction fragment which complemented a third subclass of polyhydroxyalkanoic acid (PHA)-leaky mutants of A. eutrophus that accumulated PHA at a lower rate than the wild type was cloned from Alcaligenes eUTrophus H16, and the encoded a 24-kDa protein, referred to as the GA24 protein, which seems to be a representative of phasins.
Abstract: A 5.0-kbp genomic EcoRI restriction fragment which complemented a third subclass of polyhydroxyalkanoic acid (PHA)-leaky mutants of A. eutrophus that accumulated PHA at a lower rate than the wild type was cloned from Alcaligenes eutrophus H16. A 687-bp phaPAe gene on this fragment encoded a 24-kDa protein (M(r) = 23,963), which was referred to as the GA24 protein. The GA24 protein was solubilized from the granules and purified to electrophoretic homogeneity, and antibodies against the GA24 protein were obtained. The GA24 protein bound to the surface of PHA granules, as revealed by immunoelectron microscopy of whole cells and of artificial PHA granules. The GA24 protein contributed approximately 5% (wt/wt) of the total cellular protein, and it was the predominant protein present in the granules. It was synthesized only in cells accumulating PHA and only in amounts that could be bound to the granules; no soluble GA24 protein was detected. Tn5::mob-induced phaPAe mutants which were unable to synthesize intact GA24 protein formed only one large PHA granule per cell. The amino acid sequence of the GA24 protein revealed two closely related stretches consisting exclusively of nonhydrophilic amino acids at the C-terminal region, which are presumably involved in the binding of GA24 to the granules, as was recently proposed for a similar protein in Rhodococcus ruber. The GA24 protein seems to be a representative of phasins, which are a new class of protein that form a layer at the surface of PHA granules, like oleosins, which form a layer at the surface of triacylglycerol inclusions in oilseed plants.

Journal ArticleDOI
TL;DR: A linkage map of the rapeseed genome comprising 204 RFLP markers, 2 RAPD markers, and 1 phenotypic marker was constructed using a F1 derived doubled haploid population obtained from a cross between the winter rapeseed varieties ‘Mansholt's Hamburger Raps’ and ‘Samourai’.
Abstract: A linkage map of the rapeseed genome comprising 204 RFLP markers, 2 RAPD markers, and 1 phenotypic marker was constructed using a F1 derived doubled haploid population obtained from a cross between the winter rapeseed varieties 'Mansholt's Hamburger Raps' and 'Samourai'. The mapped markers were distributed on 19 linkage groups covering 1441 cM. About 43% of these markers proved to be of dominant nature; 36% of the mapped marker loci were duplicated, and conserved linkage arrangements indicated duplicated regions in the rapeseed genome. Deviation from Mendelian segregation ratios was observed for 27.8% of the markers. Most of these markers were clustered in 7 large blocks on 7 linkage groups, indicating an equal number of effective factors responsible for the skewed segregations. Using cDNA probes for the genes of acyl-carrier-protein (ACP) and β-ketoacyl-ACP-synthase I (KASI) we were able to map three and two loci, respectively, for these genes. The linkage map was used to localize QTLs for seed glucosinolate content by interval mapping. Four QTLs could be mapped on four linkage groups, giving a minimum number of factors involved in the genetic control of this trait. The estimated effects of the mapped QTLs explain about 74% of the difference between both parental lines and about 61.7 % of the phenotypic variance observed in the doubled haploid mapping population.

Journal ArticleDOI
TL;DR: Mannose 6-phosphate receptors have been intensively studied with regard to their genomic organization, protein structure, ligand binding properties, intracellular trafficking and sorting functions, finding that their main function is sorting of newly synthesized lysosomal enzymes.


Journal ArticleDOI
TL;DR: In this article, a fully discrete method for the numerical solution of the hypersingular integral equation arising from the combined double-and single-layer approach for the exterior Neumann problem for the two-dimensional Helmholtz equation in smooth domains is described.

Journal ArticleDOI
TL;DR: Interleukin-8 is critically involved in the process of parturition in humans and concentrations in the myometrium, decidua, and membranes correlated strongly with the observed M MP-8 and MMP-9 concentrations.

Journal ArticleDOI
TL;DR: Large amounts of 5-HT are present in the mammalian intestine where the amine is concentrated in the enterochromaffin cells (ECs) of the mucosa, and receptors for vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase stimulating peptide (PACAP) and somatostatin) have been shown to be involved in the control of5-HT release from the ECs.

Journal ArticleDOI
TL;DR: Due to great genetic divergence among different populations located near the ancient glacial retreats, it was concluded that silver fir survived in five refugia during the last glaciation but migrated from only three Refugia to its present natural range.
Abstract: Silver fir presently occurs in many mountainous regions of eastern, western, southern and Central Europe. In order to elucidate the biogeographic history of fir populations in different European areas, the distribution of area-specific alleles at eight enzyme loci and the allele frequency distributions at seven polymorphic enzyme loci were investigated in seed or bud samples from 48 provenances comprising 98 single stands. Due to great genetic divergence among different populations located near the ancient glacial retreats, it was concluded that silver fir survived in five refugia during the last glaciation but migrated from only three refugia to its present natural range. The occurrence of unique alleles in particular fir areas indicated its migratory routes to the north and the existence of a few introgression zones where silver fir from different refugia has met during its expansion.

Journal ArticleDOI
01 Dec 1995-Brain
TL;DR: It is suggested that CSP and intracortical inhibition reflect the activation of cortical GABAergic mechanisms by TMS, while motor threshold does not.
Abstract: Summary The non-invasive technique of focal transcranial magnetic stimulation (TMS) was used in six healthy volunteers to evaluate the effect of ethanol on four aspects of human central motor system excitability: (i) threshold intensity for the motor evoked potential (MEP) in the resting and active abductor digiti minimi muscle (ADM): (ii) variation of MEP amplitude with increasing stimulus intensity; (iii) duration of the TMS induced cortical silent period (CSP); (iv) intracortical inhibition and facilitation after paired magnetic stimulation. In addition, the maximum M wave (Mmax) after supra-maximal electrical ulnar nerve stimulation and the peripheral silent period (PSP) have been tested as parameters of peripheral motor excitability. Baseline measurements were compared with data obtained on a mean ethanol blood concentration of 0.8 ml/l. Resting and active motor thresholds remained unchanged. Also, the absolute Mmax values and the MEP/Mmax ratio at various TMS intensities were not affected by ethanol. The mean CSP duration was prolonged by up to 35 ms while the PSP duration showed no change. The principal effect of ethanol was an enhancement of intracortical inhibition and a suppression of intracortical facilitation. These results are discussed in relation to data from animal experiments which have shown a potentiation of r-aminobutyric acid (GABA) receptor-mediated currents as the main mode of action of ethanol in the mammalian cortex. It is suggested that CSP and intracortical inhibition reflect the activation of cortical GABAergic mechanisms by TMS, while motor threshold does not

Book ChapterDOI
01 Jan 1995
TL;DR: In this paper, the authors show that exposure to alteration under atmospheric conditions, weathering and hydration of the alkali carbonates at the surface produce distinctly higher δ18O and also heavier δ13C values.
Abstract: Carbon and oxygen isotopic compositions of nyerereite and gregoryite phenocrysts and wholerock samples of natrocarbonatite lavas from the June 1988 eruption of Oldoinyo Lengai lie within restricted ranges of δ13C −6.3 to −7.1 and 5.8 to 6.7 for δ18O. These δ18O and δ13C values from unaltered natrocarbonatites and their carbonate phenocrysts support the conclusion that the carbonatitic magma was derived from the mantle and that their isotope composition was not changed by secondary isotopic exchange. Exposure to alteration under atmospheric conditions, weathering and hydration of the alkali carbonates at the surface produce distinctly higher δ18O, and also heavier δ13C values. A recent natrocarbonatite exposed to weathering for only several weeks shows δ18O and δ13C values of 17.4 and −3.3‰, respectively.

Journal ArticleDOI
TL;DR: It is verified the existence of a well-defined zone with a distinct profile of neuronal activity between the rostral Bötzinger complex containing expiratory neurons and the more caudal medullary pool of inspiratory neurons of the ventral respiratory group (VRG) in the para-ambigual region, which corresponds to the pre-BOTC.
Abstract: 1. Patterns of respiratory neuronal activity were examined in pentobarbitone anesthetized adult cats in a circumscribed area of the ventrolateral medulla, which has previously been defined as the p...

Journal ArticleDOI
TL;DR: The hypothesis that sunscreens do not protect against melanoma is supported, probably because of their ability to delay or avoid sunburn episodes, which may allow prolonged exposure to unfiltered ultraviolet radiation.
Abstract: Use of sunscreens is widely advocated as a preventive measure against sun-induced skin cancers. However, to date, no epidemiologic study has reported a decreased melanoma risk associated with sunscreen use. We have conducted a case-control study aimed at evaluating the influence of sunscreen use on the occurrence of cutaneous malignant melanoma. In 1991 and 1992, 418 melanoma cases and 438 healthy controls were interviewed in Germany, France and Belgium. The questionnaire used differentiated between regular sunscreens, psoralen sunscreen (prepared with 5-methoxypsoralen, a tanning activator and photocarcinogen), and self-tanning cosmetics (which produce a tan without ultraviolet radiation). After adjusting for age, sex, hair colour and holiday weeks spent each year in sunny resorts, the melanoma risk was of 1.50 (95% Cl:1.09-2.06) for regular sunscreens, and of 2.28 (95% Cl: 1.28-4.04) for psoralen sunscreens. No melanoma risk was associated with use of self-tanning cosmetics. Among subjects with a poor ability to tan, psoralen sunscreen users displayed a melanoma risk of 4.45 (95% Cl: 1.25-15.8) when compared with regular sunscreen users. There was a significant negative interaction between regular sunscreen use and sunburns experienced in adulthood. Use of sunscreens, especially psoralen sunscreen, was associated with higher density of pigmented lesions of the skin. Although we cannot exclude the presence of an unknown confounding factor, our results support the hypothesis that sunscreens do not protect against melanoma, probably because of their ability to delay or avoid sunburn episodes, which may allow prolonged exposure to unfiltered ultraviolet radiation. Serious doubts are raised regarding the safety of sunscreens containing psoralens.

Journal ArticleDOI
TL;DR: It is proposed that the heterogeneity of the Man-6-P recognition marker within a lysosomal protein and among different lysOSomal proteins has necessitated the evolution of two MPRs with complementary binding properties to ensure an efficient targeting of lysoomal proteins.