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Biomedical subjects

J Reiser

Publications and source records attributed to J Reiser.

At least 55 records · Page 3Linked to original sources
PubMed1991

Hydrocarbon assimilation and biosurfactant production in Pseudomonas aeruginosa mutants.

We isolated transposon Tn5-GM-induced mutants of Pseudomonas aeruginosa PG201 that were unable to grow in minimal media containing hexadecane as a carbon source. Some of these mutants lacked extracellular rhamnolipids, as shown by measuring the surface and interfacial tensions of the cell culture supernatants. Furthermore, the concentrated culture media of the mutant strains were tested for the presence of rhamnolipids by thin-layer chromatography and for rhamnolipid activities, including hemolysis and growth inhibition of Bacillus subtilis. Mutant 65E12 was unable to produce extracellular rhamnolipids under any of the conditions tested, lacked the capacity to take up 14C-labeled hexadecane, and did not grow in media containing individual alkanes with chain lengths ranging from C12 to C19. However, growth on these alkanes and uptake of [14C]hexadecane were restored when small amounts of purified rhamnolipids were added to the cultures. Mutant 59C7 was unable to grow in media containing hexadecane, nor was it able to take up [14C]hexadecane. The addition of small amounts of rhamnolipids restored growth on alkanes and [14C]hexadecane uptake. In glucose-containing media, however, mutant 59C7 produced rhamnolipids at levels about twice as high as those of the wild-type strain. These results show that rhamnolipids play a major role in hexadecane uptake and utilization by P. aeruginosa.

Alkanes↗
PubMed1990

Characterization of lignin peroxidase-encoding genes from lignin-degrading basidiomycetes.

Two closely linked lignin peroxidase (LPO)-encoding genes (lpo) from Phanerochaete chrysosporium were isolated. Nucleotide sequence studies indicated that the two genes are separated by 1.3 kb of flanking DNA and transcribed in opposite directions. Cloned P. chrysosporium lpo gene probes have been shown to hybridize to multiple sequences present in the DNAs of the white-rot fungi, Bjerkandera adusta, Coriolus versicolor and Fomes lignosus, but no hybridization was detected with DNA from Pleurotus ostreatus. Thus, lpo gene families appear to be common in a number of lignin-degrading basidiomycetes, some of which have not yet been shown to produce LPO proteins.

Amino Acid Sequence↗
PubMed1990

Lanosterol 14 alpha-demethylase-encoding gene: systematic analysis of homologous overexpression in Saccharomyces cerevisiae using strong yeast promoters.

The Saccharomyces cerevisiae 14DM gene, encoding cytochrome P450 lanosterol 14 alpha-demethylase (14DM), was overexpressed in various S. cerevisiae strains under the control of three strong heterologous yeast transcription promoters (pADC1, pGPD, pPHO5) and under the control of its own promoter. Striking, strain-specific differences in 14DM transcription and in 14DM contents have been observed. The relative abundances of 14DM-specific mRNA and protein derived from a series of different expression plasmids were compared. It was found that the inducible PHO5 promoter in combination with the JL745 host led to the highest expression levels. 14DM-specific RNA reached up to 2% of the total cellular mRNA in this strain and approx. 3% of the total soluble yeast-cell protein was determined to be 14DM by quantitative Western blotting. By comparing the abundances of the different fusion transcripts with the transcript originating from the corresponding endogenous gene from which the promoter was derived, it could be concluded that the expression levels of the different 14DM fusion genes were far below the theoretically attainable values.

Base Sequence↗
PubMed1990

Transfer and expression of heterologous genes in yeasts other than Saccharomyces cerevisiae.

In the past few years, yeasts other than those belonging to the genus Saccharomyces have become increasingly important for industrial applications. Species such as Pichia pastoris, Hansenula polymorpha, Schizosaccharomyces pombe, Yarrowia lipolytica and Kluyveromyces lactis have been modified genetically and used for the production of heterologous proteins. For a number of additional yeasts such as Schwanniomyces occidentalis, Zygosaccharomyces rouxii, Trichosporon cutaneum, Pachysolen tannophilus, Pichia guilliermondii and members of the genus Candida genetic transformation systems have been worked out. Transformation was achieved using either dominant selection markers based on antibiotic resistance genes or auxotrophic markers in conjunction with cloned biosynthetic genes involved in amino acid or nucleotide metabolism.

Gene Expression↗
PubMed1990

House dust mite allergen levels and an anti-mite mattress spray (natamycin) in the treatment of childhood asthma.

Natamycin, a fungicide marketed as Tymasil, is claimed to reduce house dust mite numbers and would therefore be expected to improve asthma in children with mite sensitivity. We have tested this assertion by a double-blind, placebo-controlled trial. There was no significant effect on levels of Der p I in mattress dust between active and placebo groups at the end of the spraying period. Histamine inhalation challenge PC20, clinic visit symptom scores and lung function tests reflecting either large or small airways obstruction were also unchanged. Therefore this product is not a therapeutic option for mite-allergic patients using the manufacturer's recommended dose and method of administration. Other factors influencing the Der p I levels were also investigated. Of these, only month of measurement and bedroom wall humidity showed any association.

Adolescent↗
PubMed1989

Genetic transformation of the filamentous yeast, Trichosporon cutaneum, using dominant selection markers.

An efficient transformation system for the filamentous yeast, Trichosporon cutaneum, has been developed. Transformation was obtained with plasmids carrying either the Escherichia coli hygromycin B phosphotransferase-encoding gene (hph) or the Streptoalloteichus hindustanus phleomycin-resistance gene (ble), as dominant selection markers. Expression of both resistance-conferring genes was controlled by the gpd promoter and the trpC terminator, from Aspergillus nidulans. The transformation frequency was up to 500 colonies/micrograms of transforming DNA, using the ble gene, and up to 100 colonies/micrograms of transforming DNA, using the hph gene. Co-transformation frequencies using unselected DNA varied between 50 and 65%. The transforming DNA was found to consist of multiple tandem plasmid copies of high Mr. This polymeric structure, in nonselective media, was mitotically unstable, possibly indicating that it existed in an episomal state.

Aspergillus nidulans↗
PubMed1989

Expression of results of histamine challenge.

Different aspects of standardization of histamine challenges have been extensively investigated. However, several methods have been used for the actual derivation of the provocation concentration causing a 20% fall in lung function (PC20) from the results of the serial lung function tests (e.g. forced expiratory volume in 1 second [FEV1] ). We have compared these methods on a series of 21 histamine challenges to see if any were systematically inconsistent with the others. The simplest method, with least potential for further error, is interpolation of two points, on either side of the line for 20% fall in lung function, calculated by computer. We conclude that, as this method was consistent with the majority of others, it is the method of choice for deriving the PC20.

Adolescent↗
PubMed1989

Inhalant allergy in asthmatic children: skin prick test, radioallergosorbent test and chemiluminescent assay compared with allergen levels in their mattress dusts.

Mattress dusts from the beds of 51 asthmatic children with positive skin tests to house dust mite were assayed for Der p I, Fel d I and certain viable fungi. The results of skin tests to grass, cat, dog, Alternaria, Aspergillus, Cladosporium and Penicillium, radioallergosorbent tests to cat, mite, dog and grass and the chemiluminescent assay were compared and correlations made with allergen concentrations in the dust. The sensitivity of the three tests appeared comparable (percentage agreement = 54.5-94), however, an increased level of allergen in the mattress dust was not a good indicator of the degree of sensitization of the child (p greater than 0.05).

Allergens↗
PubMed1988

Molecular analysis of a Phanerochaete chrysosporium lignin peroxidase gene.

The basidiomycete fungus Phanerochaete chrysosporium produces a number of extracellular peroxidases which appear to be important for lignin degradation. We present here the isolation and complete nucleotide (nt) sequence of a gene (lpo) coding for lignin peroxidase (LPO), the coding region of which is identical to a lpo cDNA sequence which had previously been described [M. Tien and C.-P.D. Tu, Nature 326 (1987) 520-523]. The deduced amino acid (aa) sequence corresponds to 372 aa residues and the coding region is interrupted by eight short introns that range in size from 50 to 62 nt. Southern blot experiments using the cloned lpo gene as hybridization probe revealed a complex restriction fragment pattern, indicating that there are a number of lpo-related nucleotide sequences present in P. chrysosporium DNA which cross-hybridize. We also present data on the in vivo expression of the lpo genes and show that they are regulated at the RNA level and that the structure of the transcripts as judged from S1 experiments is complex. These data are consistent with the idea that there are a number of related lpo genes in P. chrysosporium which constitute a gene family.

Base Sequence↗
PubMed1988

Ciliary abnormalities in respiratory disease.

One hundred and sixty seven children, ranging in age from 5 weeks to 16 years, with chronic upper or lower respiratory tract problems, or both, were investigated for ciliary dyskinesia. Abnormal ciliary function was found in 18 cases all of whom had chronic lower respiratory disease and most of whom also had upper respiratory problems. Fifteen of the 18 cases had reduced ciliary beat frequencies (less than 10 Hz) associated with dyskinesia and the other three showed apparent absence of ciliated cells. Of the 15 cases with reduced ciliary beat frequencies, ciliary ultrastructure was normal in seven cases but abnormal with missing dynein arms and occasional abnormalities of microtubular arrangement in eight. Respiratory symptoms in the perinatal period were more common in children with abnormal ciliary function and present in all those with ultrastructural abnormalities or absence of ciliated cells compared with 34 (26%) of 132 children, in whom symptoms were recorded, with normal ciliary function. This study would suggest that all children with unexplained chronic respiratory disease, in particular those with symptoms starting in the perinatal period, should be investigated for ciliary dyskinesia.

Adolescent↗
PubMed1987

Comparison of relative susceptibilities of Candida species to three antifungal agents as determined by unstandardized methods.

Three groups of isolates, each comprising four isolates of Candida species, were selected for their diversity of susceptibilities to amphotericin B, flucytosine, or ketoconazole. The isolates were distributed in duplicate and in blinded fashion to three laboratories where a total of eight procedures were performed for each drug. From the decoded results, intralaboratory variability among replicate determinations was found usually to fall within a fourfold range. Interlaboratory variation, however, was 16-fold or greater for all isolates, ranging to 50,000-fold differences for some isolates. Relative susceptibilities of isolates within each method could be determined in 11 of the 24 drug-method combinations and agreed with the reference rank order in all but one instance. Our findings underscore the lack of agreement among laboratories for the susceptibility testing of yeasts but indicate that such differences could likely be resolved by standardization without loss of clinical value.

Agar↗
PubMed1987

Cell-associated hemagglutinin-deficient mutant of Vibrio cholerae.

Cell-associated hemagglutinin-negative mutants were derived from cholera enterotoxin-negative Vibrio cholerae JBK70 by Tn5 mutagenesis. One of the mutants identified, SB001, was characterized in greater detail. Its ability to colonize ilea of adult rabbits was determined by feeding approximately 10(8) V. cholerae to each animal. At 17 h after feeding, the numbers of viable vibrios in the ilea were determined. There was a significant, 4 log, decrease in the ability of the hemagglutinin-negative mutant to colonize ileal tissue compared with the parent strain JBK70. In addition, the higher levels of colonization attained by JBK70 and the wild-type parent of JBK70, N16961, were associated with intestinal fluid accumulation and death. Rabbits immunized orally with approximately 10(8) SB001, when challenged 3 weeks later with either homologous biotype and serotype El Tor Inaba N16961 or heterologous Classical Ogawa 395, were protected to the same extent as those animals immunized with either the challenge strain or JBK70. This was evidenced by decreases in both the number of animals showing detectable colonization and the level of colonization achieved. A hemagglutinin-negative mutant of V. cholerae may therefore be of potential use as a live oral vaccine against cholera.

Administration, Oral↗
PubMed1986

Sequence requirements for splicing of higher eukaryotic nuclear pre-mRNA.

We determined the effect on splicing of 24 point mutations in the 5' and 3' splice region of the large rabbit beta-globin intron. In vitro, 3' AG mutations drastically reduce 5' cleavage and abolish splicing. In vivo, the same mutations elicit efficient splicing at a cryptic, rather than the correct, 3' splice site. In vitro, mutations at all but 2 positions of the consensus 5' splice region impair correct splicing and promote joining of exon 1 to exon 3. In vivo, the same mutations show no effect, except for those converting 5' GT to AT or GA, which cause accumulation of lariat intermediate in vitro and in vivo. We conclude that the 5' GT need not be conserved for 5' cleavage and that it plays an important role in cleavage and exon joining at the 3' splice site.

Animals↗
PubMed1986

The effect of zaprinast (M&B 22,948, an orally absorbed mast cell stabilizer) on exercise-induced asthma in children.

We conducted a placebo controlled, double-blind trial on the effect of a single dose of zaprinast (M&B 22,948, an orally active mast cell stabilizer) on exercise-induced asthma in 15 children. We demonstrated no prophylactic effect on the whole group. A trend towards effectiveness was shown when the results for children whose asthma was not steroid dependent were analysed alone.

Adolescent↗
PubMed1986

Inhalation treatment for asthma.

Inhaled medication has revolutionised the lives of many children with asthma. Despite this we see many children for whom appropriate inhaled medication has been prescribed but whose symptoms continue to be poorly controlled. In our experience this is often due to poor technique or inappropriately prescribed devices and an inadequate understanding of when and how to use the treatment. The prescribing physician must have a clear idea of the optimal inhalation technique. We have reviewed the standard devices available and our use of them in the treatment of childhood asthma.

Adolescent↗
PubMed1985

Asthma in childhood.

For the majority of children with asthma treatment is simple and effective and they can lead normal active lives. Unfortunately, many cases of asthma go unrecognized or undertreated, leading to much chronic ill health and missed schooling. The mechanisms underlying asthma and some basic approaches to diagnosis and management are outlined in this article.

Adrenergic beta-Agonists↗