Identifying the pre-diabetic state in type I diabetics: condition for early intervention.
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Autoantibodies↗
Biomedical subjects
S Scherer
Publications and source records attributed to S Scherer.
Comparison of RFLP-DR beta and serological HLA-DR typing in 1500 individuals.
A group of 1522 individuals were HLA-DR-typed both by the standard serological technique and by the RFLP method. Whereas 11% (n = 164) of the serological typings were technically unsuccessful or doubtful, all typings were successful by RFLP. The results of the remaining 1358 typings revealed a serological error rate of 25%. In 16% a serological "blank" turned out to be a definable allele by RFLP, while in 9% an allele was incorrectly interpreted by serology. Of the individuals tested, 11% were HLA-DR homozygous by RFLP. Our results demonstrate an important clinical potential of RFLP typing for the typing of bone marrow transplant candidates in whom serology often fails, and for kidney transplant candidates with "blanks" or serologically "difficult" HLA antigens.
Alleles↗
Genetics of Candida albicans.
Candida albicans is among the most common fungal pathogens. Infections caused by C. albicans and other Candida species can be life threatening in individuals with impaired immune function. Genetic analysis of C. albicans pathogenesis is complicated by the diploid nature of the species and the absence of a known sexual cycle. Through a combination of parasexual techniques and molecular approaches, an effective genetic system has been developed. The close relationship of C. albicans to the more extensively studied Saccharomyces cerevisiae has been of great utility in the isolation of Candida genes and development of the C. albicans DNA transformation system. Molecular methods have been used for clarification of taxonomic relationships and more precise epidemiologic investigations. Analysis of the physical and genetic maps of C. albicans and the closely related Candida stellatoidea has provided much information on the highly fluid nature of the Candida genome. The genetic system is seeing increased application to biological questions such as drug resistance, virulence determinants, and the phenomenon of phenotypic variation. Although most molecular analysis to data has been with C. albicans, the same methodologies are proving highly effective with other Candida species.
Animals↗
RFLP-DR beta and serological HLA-DR typing of 200 kidney recipients and 1000 controls.
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DNA↗
Novel water stress protein from a desiccation-tolerant cyanobacterium. Purification and partial characterization.
A desiccation-tolerant cyanobacterium Nostoc commune accumulates a novel group of acidic proteins when colonies are subjected to repeated cycles of drying and rehydration. The proteins occur in high concentrations; they have isoelectric points between 4.3 and 4.8 and apparent molecular masses between 30 and 39 kDa. The purification of three of these proteins with molecular masses of 33, 37, and 39 kDa is described. The amino-terminal sequence of the 39-kDa protein is Ala-Leu-Tyr-Gly-Tyr-Thr-Ile-Gly-Glu. Peptide mapping of the 39- and the 33-kDa proteins, using different protease, gave similar patterns of digestion fragments. The amino acid compositions of the proteins isolated were similar, and each cross-reacted with a polyclonal antibody raised against the largest (39-kDa) protein. The results indicate that the microheterogeneity observed was generated by in vivo proteolysis of the 39-kDa protein. It is suggested that this protein is a water stress protein with a protective function on a structural level.
Amino Acid Sequence↗
Pulsed-field gel electrophoresis of circular DNA.
Mobility of supercoiled (form I) and nicked circular (form II) plasmid DNAs was determined on two major forms of pulsed-field electrophoresis, CHEF and OFAGE. Plasmids with molecular lengths ranging from 2.30 to 17.8 kilobase pairs (kb) were used with Saccharomyces cerevisiae chromosomes as standards. Agarose gel concentrations were varied from 0.3 to 2.0 percent, with higher percentage gels resolving forms I and II of smaller plasmids. The pulsing range of 3.7 to 240 seconds resulted in quite variable Saccharomyces chromosomal mobilities on both 0.5 and 1.0 percent gels, while both form I and II of all plasmid DNAs showed relatively constant mobilities with some increase at the shortest pulse times. Using a 30 second pulse time and gel concentrations of at least 1.0 percent, the usual order of migration of plasmid forms for a 17.8 kb plasmid could be changed. We interpret this result as an increase in the relative mobility of form II in our pulsed-field gel conditions.
Chromosomes↗
Genetic analysis of prototrophic natural variants of Candida albicans.
To facilitate genetic analysis of Candida albicans natural variants, we have isolated a dominant mycophenolic acid-resistant mutant. Mycophenolic acid-resistant auxotrophs were used to analyze prototrophic natural variants by spheroplast fusion. The fusion products were shown to be heterozygous for many of the parental chromosomes by molecular and genetic criteria. Using this approach, we have found that one type of morphologic variation is due to a recessive change and identified three dominant 5-fluorocytosine-resistant mutants. Rare fusion products express recessive parental markers. These exceptional progeny should be useful for linkage analysis and strain construction.
Candida albicans↗
The relative-rate test of the molecular clock hypothesis: a note of caution.
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Animals↗
Nature of the light-induced h efflux and na uptake in cyanobacteria.
We investigated the nature of the light-induced, sodium-dependent acidification of the medium and the uptake of sodium by Synechococcus. The rate of acidification (net H(+) efflux) was strongly and specifically stimulated by sodium. The rates of acidification and sodium uptake were strongly affected by the pH of the medium; the optimal pH for both processes being in the alkaline pH range. Net proton efflux was severely inhibited by inhibitors of adenosine triphosphatase activity, energy transfer, and photosynthetic electron transport, but was not affected by the presence of inorganic carbon (C(i)). Light and C(i) stimulated the uptake of sodium, but the stimulation by C(i) was observed only when C(i) was present at the time sodium was provided. Amiloride, a potent inhibitor of Na(+)/H(+) antiport and Na(+) channels, stimulated the rate of acidification but inhibited the rate of sodium uptake. It is suggested that acidification might stem from the activity of a light dependent proton excreting adenosine triphosphatase, while sodium transport seems to be mediated by both Na(+)/H(+) antiport and Na(+) uniport.
Journal Article↗
Magnetic resonance imaging of ataxic hemiparesis localized to the corona radiata.
A 61-year-old woman developed right hemiparesis with homolateral cerebellar-type ataxia. Computed tomography and magnetic resonance imaging demonstrated left corona radiata lesions, not present on magnetic resonance imaging 1 year earlier. No brainstem lesions were identified, suggesting that ataxic hemiparesis can result from lesions in the corona radiata.
Ataxia↗
Ferredoxin-NADP+ oxidoreductase is the respiratory NADPH dehydrogenase of the cyanobacterium Anabaena variabilis.
The NADPH dehydrogenase of the cyanobacterium Anabaena variabilis was solubilized, purified, and characterized. Activity staining after nondenaturing polyacrylamide gel electrophoresis, kinetics, and immunological characterization led to the conclusion that only one thylakoid-associated NADPH dehydrogenase exists in Anabaena, identical with ferredoxin-NADP+ oxidoreductase (FNR). After sodium dodecyl sulfate-polyacrylamide gel electrophoresis an intense band at 34 kDa and a weak band at 52 kDa were found by immunoblotting with an antibody against Anabaena FNR. Using a cell-free preparation competent of oxidative phosphorylation it was demonstrated that FNR operates as a respiratory NADPH dehydrogenase coupled to cyanide-sensitive oxidative ATP formation.
Cyanobacteria↗
A Candida albicans dispersed, repeated gene family and its epidemiologic applications.
Candida albicans causes a wide variety of infections but can readily be isolated from the skin and mucosa of healthy individuals. To enable high-resolution epidemiologic studies on this common pathogen, a species-specific DNA probe has been isolated from its genome. There are approximately equal to 10 copies of the sequence dispersed among the chromosome-sized DNA molecules resolved by pulsed-field electrophoresis. New DNA polymorphisms in this gene family arise at high rates. As a consequence, this probe will readily distinguish strains from different patients in the same hospital and from various sites in individual patients. The DNA polymorphisms detected by using this probe are largely due to internal changes in members of the family rather than movement to new genomic locations. This suggests recombination or gene conversion rather than transposition as the mechanism producing the observed variation.
Candida albicans↗
Light-Induced Proton Release by the Cyanobacterium Anabaena variabilis: Dependence on CO(2) and Na.
Light-induced acidification by the cyanobacterium Anabaena variabilis is biphasic (a fast phase I and slow phase II) and shown to be sodium-dependent with an optimum concentration of 40 to 60 millimolar Na(+). Cells grown under low CO(2) concentrations at pH 9 (i.e. mainly HCO(3) (-) present in the medium) exhibited the slow phase II of proton efflux only, while cells grown under low CO(2) concentrations at pH 6.3 (i.e. CO(2) and HCO(3) (-) present) exhibited both phases. Light-induced proton release of phase I was dependent on inorganic carbon available in the bathing medium with an apparent K(m) for CO(2) of 20 to 70 micromolar. As was concluded from the CO(2) dependence of acidification measured at different pH of the bathing medium, bicarbonate inhibited phase-I acidification noncompetetively. Acidification was inhibited by acetazolamide, an inhibitor of carbonic anhydrase. Apparently, acidification of phase I is due to a light-dependent uptake of CO(2) being converted to HCO(3) (-) by a carbonic anhydrase-like function of the HCO(3) (-)-transport system (M Volokita, D Zenvirth, A Kaplan, L Reinhold 1984 Plant Physiol 76: 599-602) before or during entering the cell, thus releasing one proton per CO(2) converted to HCO(3) (-).
Journal Article↗
A New UV-A/B Protecting Pigment in the Terrestrial Cyanobacterium Nostoc commune.
A new ultraviolet (UV)-A/B absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium Nostoc commune is described. The pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar UV radiation but only in low concentrations in laboratory cultures illuminated by artificial light without UV. Its experimental induction by UV as well as its capacity to efficiently protect Nostoc against UV radiation is reported.
Journal Article↗
Application of DNA typing methods to epidemiology and taxonomy of Candida species.
Methods are described for extraction of DNA from the yeast form of Candida spp., followed by digestion and electrophoresis of DNA fragments. The resulting gel patterns (greater than 100 bands) were used to type Candida isolates. Four intense bands identified, three of which are present in each isolate (6 to 7, 3.7 or 4.2, and 2.5 to 3 kilobases), appear to be DNA encoding the rRNA. The methods proved to be both simple and reproducible. The patterns were shown to be stable through several hundred doublings from multiple single colonies. A survey of isolates showed that, on the basis of similarity of gel patterns, several Candida species could be sorted into mutually exclusive groups, and subgroups could be created. Analyses of this survey suggested the possible epidemiologic and taxonomic applications of these methods. DNA typing methods appear to offer important potential advantages over phenotyping methods. The methods provide a base for further epidemiologic studies and for further development of techniques, such as the use of cloned probes for studies of DNA homology.
Candida↗
Regulated yeast promoters produced by DNA rearrangements selected in vivo.
DNA rearrangements that activated a promoterless his3 gene were selected in vivo. DNA segments that promote the expression of his3 were identified in Ty1 DNA sequences and a variety of sites in the vector DNA. These elements appear to function when placed in either orientation relative to his3 but not when placed at the 3' end of the his3 gene. Promoter elements regulated by carbon source, nitrogen source, pyrimidines or galactose were characterized. The assembly of more complex regulatory elements and transposons from these units is discussed.
Base Sequence↗
Effect of Monochromatic Light on Proton Efflux of the Blue-Green Alga Anabaena variabilis.
Light-induced proton efflux of Anabaena variabilis was found to be biphasic, the second phase being inhibited by the ATPase inhibitor nitrofen (2,4-dichloro-1-[4-nitrophenoxy]benzene). The first, fast phase was triggered by monochromatic light of 707 nanometers, whereas the second, slower phase was not. With 707 nanometers, light, respiratory O(2) uptake was inhibited. Using light composed of two wavelengths (616 and 707 nanometers) a marked enhancement of both O(2) evolution as well as the second phase of proton efflux was observed. The first phase was not enhanced. Thus, phase II is driven by both photosystems. As concluded from the action spectrum phase I is markedly determined by photosystem-I activity. Altogether the data show that two different mechanisms of light-induced proton efflux exist on the cytoplasmic membrane of Anabaena, the slower one being dependent on ATP and linear photosynthetic electron flow.
Journal Article↗
Could life have arisen in the primitive atmosphere?
A recently proposed model for the origin of prebiotic progenitors of life in particles suspended in a primitive, specially organized atmosphere is considered critically. It is concluded that the physical and chemical framework of the new hypothesis conflicts with the conditions necessary for the evolution of the progenitors of life in the atmosphere of the early Earth. Therefore this model seems not to be a reasonable alternative to the Oparin thesis.
Atmosphere↗