PubMed Health⌕ Search

Biomedical subjects

M Penttilä

Publications and source records attributed to M Penttilä.

At least 73 records · Page 4Linked to original sources
PubMed1995

Endoscopic and Caldwell-Luc approaches in chronic maxillary sinusitis: a comparative histopathologic study on preoperative and postoperative mucosal morphology.

The aim of the present investigation was to study the histopathologic mucosal changes occurring in chronic maxillary sinusitis both preoperative and postoperative to functional endoscopic sinus (FES) surgery and the Caldwell-Luc (C-L) operation. Correlations were also sought between the histopathologic parameters and endoscopic findings, as well as patient symptoms. Sixty sinuses with the FES surgery and 55 sinuses with the C-L procedure were studied. The histologic parameters were graded semiquantitatively and compared preoperatively and postoperatively. The C-L operation reduced almost all parameters, whereas after the FES operation only edema and inflammatory cells were significantly reduced. Fibrosis increased postoperatively with both methods. The number of inflammatory cells was closely correlated to a thickened antral mucosa and to purulent secretion. No valid correlations were found when comparing histology with patient symptoms. All in all, histologic considerations suggest that asthmatic patients with severe sinonasal polyposis might benefit from the C-L procedure.

Asthma↗
PubMed1994

Molecular cloning and analysis of the yeast flocculation gene FLO1.

The DNA sequence of the flocculation gene FLO1 of Saccharomyces cerevisiae, which is located on chromosome I (Watari et al., 1989) was determined. The sequence contains a large open reading frame (ORF) of 2586 bp and codes for a protein of 862 amino acids. However, further study (genomic Southern and polymerase chain reaction analyses) indicated that the gene we cloned was not the intact FLO1 gene but a form with an approximately 2 kb deletion in the ORF region. The intact FLO1 gene was then cloned and its nucleotide sequence determined. The sequence revealed that the ORF of the intact gene is composed of 4611 bp which code for a protein of 1537 amino acids. A remarkable feature of the putative Flo1 protein is that it contains four families of repeated sequences composed of 18, 2, 3 and 3 repeats and that it has a large number of serines and threonines. In the deleted FLO1 form, a large part of these repeated sequences was missing. The N- and C-terminal regions are hydrophobic and both contain a potential membrane-spanning region, suggesting that the Flo1 protein is an integral membrane protein and a cell wall component.

Amino Acid Sequence↗
PubMed1994

The influence of cosubstrate and aeration on xylitol formation by recombinant Saccharomyces cerevisiae expressing the XYL1 gene.

Xylitol formation by a recombinant Saccharomyces cerevisiae strain containing the XYL1 gene from Pichia stipitis CBS 6054 was investigated under three sets of conditions: (a) with glucose, ethanol, acetate, or glycerol as cosubstrates, (b) with different oxygenation levels, and (c) with different ratios of xylose to cosubstrate. With both glucose and ethanol the conversion yields were close to 1 g xylitol/g consumed xylose. Decreased aeration increased the xylitol yield on the basis of consumed cosubstrate, while the rate of xylitol formation decreased. The xylitol yield based on consumed cosubstrate also increased with increased-xylose:cosubstrate ratios. The transformant utilized the cosubstrate more efficiently than did a reference strain in terms of utilization rate and growth rate, implying that the regeneration of NAD(P)+ during xylitol formation by the transformant balanced the intracellular redox potential.

Aerobiosis↗
PubMed1994

A novel, small endoglucanase gene, egl5, from Trichoderma reesei isolated by expression in yeast.

A method is presented for the isolation of genes encoding hydrolytic enzymes without any knowledge of the corresponding proteins. cDNA made from the organism of interest is cloned into a yeast vector to construct an expression library in the yeast Saccharomyces cerevisiae. Colonies producing hydrolytic enzymes are screened by activity plate assays. In this work, we constructed a yeast expression library from the filamentous fungus Trichoderma reesei and isolated a new beta-1,4-endoglucanase gene on plates containing beta-glucan. This gene, egl5, codes for a previously unknown small protein of 242 amino acids. Despite its small size, the protein contains two conservative domains found in Trichoderma cellulases, namely the cellulose-binding domain (CBD) and the linker region that connects the CBD to the catalytic core domain. Molecular modelling of the EGV CBD revealed some interesting structural differences compared to the CBD of the major cellulase CBHI from T. reesei. The catalytic core of EGV is unusually small for a cellulase and represents a new family of cellulases (Family K) and of glycosyl hydrolases (Family 45) together with the endoglucanase B of Pseudomonas fluorescens and the endoglucanase V of Humicola insolens on the basis of hydrophobic cluster analysis.

Amino Acid Sequence↗
PubMed1994

Comparison of immunologic tests in the diagnosis of occupational asthma and rhinitis.

In this study, three immunologic tests, skin prick test, RAST, and basophil histamine-release test (BHRT), were compared by provocation in the diagnosis of occupational asthma and rhinitis. Twenty-three positive bronchial or nasal challenges were performed on 16 patients (six farmers, six bakery workers, and four food industry workers) and asthma or rhinitis was diagnosed as caused by cereal flour or grain, cow epithelium, storage mites, garlic, or soy dust. A control group consisted of 12 patients, of whom four (two bakery workers, one food industry worker, and one farmer) were challenge-negative, and the rest suffered from pollen allergy and seasonal rhinitis and were not challenged. The sensitivity and specificity of the prick test, RAST, BHRT, and a panel of them were as follows: 74 and 89%, 57 and 86%, 78 and 93%, and 91 and 71%, respectively. The overall concordance among these three type I allergy tests or between immunologic tests and challenge was relatively good.

Adult↗
PubMed1993

Role of the interdomain linker peptide of Trichoderma reesei cellobiohydrolase I in its interaction with crystalline cellulose.

Cellobiohydrolase I (CBH I), the major component of Trichoderma reesei cellulolytic system, is comprised of a catalytic core domain joined to a cellulose binding-domain (CBD) by an extended O-glycosylated interdomain linker peptide. Two internal deletions were introduced to the linker in order to investigate its function particularly in the hydrolysis of crystalline cellulose. Deletion of the first one-third of the linker, including a putative hinge region, reduces the binding capacity of CBH I in high enzyme coverage but does not affect its enzymatic activity on crystalline cellulose. The longer deletion removing practically all of the linker dramatically reduces the rate of crystalline cellulose degradation even though the enzyme still binds to the substrate. We conclude that sufficient spatial separation of the two domains is required for efficient function of CBH I. It is evident that the presence of a functional CBD is increasingly important for CBH I toward higher enzyme to cellulose ratios. Our data suggest that the putative hinge removed by the first deletion facilitates CBD-driven binding and dense packing of the wild type enzyme on the cellulose surface.

Adsorption↗
PubMed1993

Dual relationships of xylitol and alcohol dehydrogenases in families of two protein types.

Xylitol dehydrogenase encoded by gene XYL2 from Pichia stipitis is a member of the medium-chain alcohol dehydrogenase family, as evidenced by the domain organization and a distant homology (24% residue identity with the human class I gamma 1 alcohol dehydrogenase). Much of a loop structure is missing, like in mammalian sorbitol and prokaryotic threonine dehydrogenases, many additional differences occur, and relationships are closest with the sorbitol dehydrogenase, the equivalence of which in P. stipitis may actually be the xylitol dehydrogenase. A second P. stipitis gene, also cloned and corresponding to a xylitol dehydrogenase, is highly different from XYL2, but encodes an enzyme with structural properties typical of the short-chain dehydrogenase family, which also contains an alcohol dehydrogenase (from Drosophila). Thus, yeast xylitol dehydrogenases, like alcohol and polyol dehydrogenases from other sources, have dual derivations, combining similar enzyme activities in separate protein families. In contrast to the situation with the other enzymes, both forms of xylitol dehydrogenase are present in one organism.

Alcohol Dehydrogenase↗
PubMed1993

Efficient production of antibody fragments by the filamentous fungus Trichoderma reesei.

We have engineered the filamentous fungus Trichoderma reesei to assemble and secrete immunologically authentic engineered Fab antibody fragments into the culture medium. A major improvement in yield was achieved by fusing the heavy Fd chain to the T. reesei cellulase, CBHI. The yields of secreted, immunologically active Fab and CBHI-Fab fusion were 1 mg/l and 150 mg/l, respectively. The Fab fragment can be released from the fusion protein CBHI-Fab by an extracellular T. reesei protease. There was no detectable difference in affinity for the antigen between the engineered Fab and the idiotypic antibody.

Amino Acid Sequence↗
PubMed1991

Promoter structure and expression of the 3-phosphoglycerate kinase-encoding gene (pgk1) of Trichoderma reesei.

Transcription of the 3-phosphoglycerate kinase (PGK)-encoding gene (pgk1) of Trichoderma reesei results in two transcripts due to two main transcription start points (tsp) which are differentially regulated during the growth cycle. The nucleotide sequence of the promoter reveals a number of putative regulatory elements present also in the PGK promoter of Saccharomyces cerevisiae: a 20-nt long sequence similar to the CTTCC-repeat region of the upstream activating sequence UAS, the eukaryotic heat-shock consensus sequence, HSE, and a putative eukaryotic cAMP regulatory sequence. The functionality of the putative HSE sequence was examined, but no clear effect could be seen on the total amount of pgk1 mRNA at elevated temperatures nor on transcription initiation from the upstream tsp, preceded by the HSE sequence.

Amino Acid Sequence↗
PubMed1991

Azithromycin concentrations in sinus fluid and mucosa after oral administration.

The concentrations of azithromycin in sinus fluid and mucosal tissue were determined in a total of 23 patients with acute or chronic sinusitis. Five patients with acute sinusitis and four with chronic sinusitis were administered a five-day course of oral azithromycin (500 mg on day 1, 250 mg on days 2-5, all as single doses), and the remaining 14 patients, all with chronic sinusitis, received single oral doses of azithromycin (500 mg). With the five-day regimen, the mean levels of azithromycin in sinus fluid were markedly higher in patients with acute sinusitis (1.34 micrograms/ml) than in patients with chronic sinusitis (0.25 micrograms/ml) 24 h after the first dose. The levels of azithromycin in the sinus fluid increased from the first to the last dose in both patient groups; the mean levels of azithromycin 24 h after the last dose were 2.33 micrograms/ml in acute sinusitis patients and 0.38 micrograms/ml in chronic sinusitis patients. In chronic sufferers, the mean levels of azithromycin in the sinus fluid following a single oral dose were 0.25, 0.41, 0.57 and 0.22 micrograms/ml at 24, 48, 72 and 96 h, respectively, after administration. In these patients the mean sinus drug concentrations were much greater in the mucosal tissue (1.23 micrograms/g) than in the sinus fluid (0.41 micrograms/ml) 48 h after administration of the single dose. There were no treatment-related changes in laboratory function tests, and side effects were described as mild to moderate (five patients complained of nausea, abdominal pain or headache).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Genetic engineering of Trichoderma to produce strains with novel cellulase profiles.

Genetic engineering has been used to modify the proportion of different cellulases produced by a hypercellulolytic Trichoderma reesei mutant strain. A general expression vector, pAMH110, containing the promoter and terminator sequences of the strongly expressed main cellobiohydrolase 1 (cbh1) gene was used to overexpress a cDNA coding for EGI, the major endoglucanase (1,4,beta-D-glucan glucanohydrolase, EC 3.2.1.4). An in vitro modified cbh1 cDNA, incapable of coding for active enzyme, was used to inactivate the major cellobiohydrolase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) gene. In this way, new strains producing elevated amounts of the specific endoglucanase 1 (EGI) and/or lacking the major cellobiohydrolase (CBHI) were produced, and these have been further characterized.

Base Sequence↗
PubMed1991

Production of functional IgM Fab fragments by Saccharomyces cerevisiae.

The aim of this study was to express and secrete functional mouse IgM fragments in yeast. The heavy chain cDNA was truncated at two different sites, yielding genes coding for the complete VH domain. In one of the truncated genes, the CH1 domain is complete, while in the other gene 18 bp are missing from the 3' terminus of the CH1 region. Both shortened genes were coexpressed in Saccharomyces cerevisiae with a cDNA gene encoding a full length mouse Ig light chain. We show that only the longer form of the truncated heavy chain together with the light chain produced and secreted functional IgM Fab fragments.

Amino Acid Sequence↗
PubMed1991

Xylitol production by recombinant Saccharomyces cerevisiae.

We obtained efficient conversion of xylose to xylitol by transforming Saccharomyces cerevisiae with the gene encoding the xylose reductase (XR) of Pichia stipitis CBS 6054. Comparison of the chromosomal and cDNA copies of the XYL1 gene showed that the genomic XYL1 contains no introns, and an XR monomer of 318 amino acids (35,985 D) is encoded by an open reading frame of 954 bp. The amino acid sequence of the P. stipitis XR is similar to several aldose reductases, suggesting that P. stipitis XR is part of the aldoketo reductase superfamily. S. cerevisiae transformed with the XYL1 gene gave over 95% conversion of xylose into xylitol, a yield not obtainable with natural xylose utilizing yeasts.

Aldehyde Reductase↗