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G Michaelis

Publications and source records attributed to G Michaelis.

At least 37 records · Page 2Linked to original sources
PubMed1991

Mitochondrial inner membrane protease 1 of Saccharomyces cerevisiae shows sequence similarity to the Escherichia coli leader peptidase.

The nuclear yeast mutant pet ts2858 is defective in the removal of pre-sequences from the mitochondrially encoded cytochrome oxidase subunit II (COXII) and the processing intermediate of cytochrome b2 (Cytb2), a nuclear gene product. In order to identify the genetic lesion in this mutant we have cloned and characterized a DNA region which complements the pet ts2858 mutation. The DNA sequence revealed three open reading frames, one of which is responsible for the complementation. A 570 bp reading frame represents the structural gene PET2858, as demonstrated by in vitro mutagenesis, gene expression from a foreign promoter, and allelism tests. PET2858 encodes a 21.4 kDa protein, which is essential for growth on non-fermentable carbon sources and for the proteolytic processing of COXII and the Cytb2 intermediate. When the N-terminus of the PET2858 protein is fused to a reporter protein, the resulting hybrid molecule is imported into mitochondria. Interestingly, the N-terminal half of the deduced PET2858 protein exhibits 30.7% amino acid identity to the leader peptidase of Escherichia coli. These results suggest that PET2858 codes for a mitochondrial inner membrane protease (IMP1) or at least a subunit of it. This protease is involved in protein processing and export from the mitochondrial matrix.

Alleles↗
PubMed1991

[Candida infections in intensive care patients].

In 31 of 60 long-term ventilated intensive-care patients, a significant Candida antigen titer in serum was found that correlated with positive Candida cultures. In some cases the detection of the antigen was the first indication of Candida infection, while the isolation of the infectious agent required a culture period of 24-48 hours. In addition to routinely performed controls of Candida colonisation, determination of Candida antigen in the serum appears to be a valuable tool in the early diagnosis of candida infections.

Antigens, Fungal↗
PubMed1991

Stereo- and sequence specificity of serine proteases in peptide synthesis.

The sequence- and stereospecificity of the S1- and S' i-subsites (i = 1-3) of bovine alpha-chymotrypsin and trypsin, proteinase K and penicillin amidase from E. coli and A. viscosus has been determined by hydrolysis and kinetically controlled peptide synthesis using different substrates. The data are compared with results for other serine proteases and the thiol protease papain. The stereospecificities differ by orders of magnitude, decreased when the enzyme was immobilized and were influenced when organic solvent molecules were bound to the enzyme.

Amino Acid Sequence↗
PubMed1991

[Microbiological care of ventilated intensive care patients. Feasibility of diagnosis and therapy of pulmonary infection].

Pulmonary infections are the most life-threatening infections in mechanically ventilated patients. Methods to avoid these infections by prophylactic systemic or local administration of antibiotics may promote resistance and selection of distinct groups of pathogens. In mechanically ventilated patients we studied the impact of early diagnosis and specific therapy on the prevention of pulmonary infections. Due to the very short interval between colonization and infection, daily microscopic and microbiologic examinations of tracheobronchial secretions proved to be essential for early and successful therapy and even prevention of pulmonary infections. PATIENTS AND METHODS. The present study comprised a total of 190 patients admitted to the surgical intensive care unit who required mechanical ventilation for a period of at least 48 h: 56 were admitted for multiple trauma; 38 had peritonitis; and the remainder had postoperative complications such as renal failure, cardiac problems, septicemia or pneumonia. Multitraumatized patients (16.5 days) and those with peritonitis (13.8 days) needed the most extensive ventilatory support. After admission antibiotic therapy was started with a second-generation cephalosporin or amoxicillin/clavulanic acid. Further antibiotic treatment was directed strictly against the isolated pathogens. Tracheobronchial secretions were monitored daily by microscopy and cultures. Microscopic evaluation was essential to discriminate between colonization and inflammation, and often indicated the infective agent. If infections were suspected provisional antibiograms were performed on the material. This procedure allowed a specific antibiotic treatment to be initiated 8-12 h later. In patients with pulmonary infections, additional bronchoscopic material was taken in order to correlate these findings with those gained from the tracheobronchial secretions. RESULTS. In 85% of cases massive colonization of the trachea with Pseudomonas aeruginosa, enterobacteria, Staphylococcus aureus or Streptococcus pneumoniae resulted in pulmonary infections 24-48 h later. The reduced virulence of Pseudomonas species (non-aeruginosa) and Acinetobacter species is reflected by an infection rate of 50% and an extended period of time to establish an infection (2-4 days). Only 30% of patients highly contaminated with Candida developed pulmonary infections after 3-6 days. A fair correlation (86%) was found between pathogens isolated in tracheobronchial secretions and bronchoscopic material. In the population studied, 68 patients (35.7%) developed pulmonary infections, 32 of them pneumonia (16.8%), and the others purulent tracheobronchitis with fever. Both groups were treated with antibiotics. Patients with multiple trauma, often accompanied by lung contusion, were most frequently affected. In 59 patients (87%) pulmonary infections were treated successfully by specific antibiotic therapy; 9 patients died so rapidly, that the pulmonary complication could not account for the fatal outcome. In 38 patients with massive contamination of the tracheobronchial system by enterobacteria, Pseudomonas aeruginosa or Staph. aureus, progression from colonization to infection was prevented by early administration of specific therapy. CONCLUSIONS. Because pulmonary infections in most cases arise very soon after pathogens have gained access to the tracheobronchial system daily monitoring of tracheobronchial secretions is required for early initiation of specific therapy.

Adolescent↗
PubMed1990

Mitochondrial DNA of Chlamydomonas reinhardtii: the gene for apocytochrome b and the complete functional map of the 15.8 kb DNA.

We have sequenced the termini of the mitochondrial genome of Chlamydomonas reinhardtii and now present the DNA sequence of the gene for apocytochrome b. This gene is the thirteenth gene of the linear 15.8 kb DNA and appears to be the last one of the mt genome. The deduced protein sequence of 381 amino acid residues shows 56%, 48.6% and 48% identity with the apocytochrome b proteins of maize, Drosophila yakuba and mouse, respectively. RNA analysis reveals a transcript of about 1250 nucleotides. It is now possible to present the complete protein-coding capacity, the pattern of codon utilization for all eight protein genes, and the complete functional map of the mitochondrial 15.8 kb DNA of C. reinhardtii. One surprising feature is the absence of mitochondrial genes for ATPase and subunits II and III of cytochrome oxidase. No more than three tRNA genes appear to be present on the 15.8 kb mitochondrial DNA.

Amino Acid Sequence↗
PubMed1990

The mitochondrial nad5 gene of sugar beet (Beta vulgaris) encoding a subunit of the respiratory NADH dehydrogenase.

We have isolated the nad5 gene from the N-cytoplasm of Beta vulgaris, by heterologous hybridization with a nad5 probe from Chlamydomonas reinhardtii, and have determined the DNA sequence. The gene has a length of 3082 bp and consists of three exons and two introns, 459, 1269, 270, 848 and 357 bp in length, respectively. It has a similarity of 95.1% at the DNA level to the nad5 gene of Oenothera and the two respective proteins show an overall level of amino acid identity of 88.7%. Compared to Oenothera the reading frame of the first exon is extended in the 5' direction and in the third exon there is a frameshift shortening the reading frame by 96 bp and changing the last 48 codons. The nad5 gene is a single copy gene in the N- and S-cytoplasm of Beta vulgaris and the organisation of the gene shows no apparent differences in the two cytoplasms. The gene is actively expressed; three major transcripts are detectable. The transcript patterns have been compared between the two cytoplasms and between different plant tissues.

Amino Acid Sequence↗
PubMed1990

[Neurologic complication following spinal anesthesia for manual detachment of the placenta].

Long-term paralysis of the lower extremities was observed in a 31-year-old fourth-gravida patient, undergoing a curettage under spinal anaesthesia because of placenta accreta. The patient recovered within three days from her neurological signs and symptoms, consisting of complete paresis of the hip and knee flectors and severe headache. Clinical investigations including a neurological examination, spinal puncture, x-ray pictures of the lumbosacral area and haemograms revealed no evidence for an infection, abscess or haematoma. With regard to the fact, that neurological deficiency disappeared completely within three days, it seems probable, that the symptoms were caused by the longer lasting gynaecological position (Steinschnitt-position) during the period of delivery and curettage thereafter.

Adult↗
PubMed1990

[Postoperative course and endocrine stress reaction of geriatric patients with para-articular hip fractures. Prospective randomized study comparing spinal anesthesia and halothane intubation narcosis].

During a period of one year, all patients above the age of 60 with surgical repair of fractured neck of femur were investigated in a prospectively randomized design. A follow-up study included a total number of 56 patients, 32 were allocated to halothane anaesthesia with intubation, 24 received spinal anaesthesia. In addition, 15 patients of the halothane group and 17 patients with spinal anaesthesia were investigated with regard to endocrine stress response. Total mortality was 12.5%, and different anaesthetic management had no influence on the postoperative course. During the operation, adrenaline and ADH increased in both groups. This increase was attenuated by spinal anaesthesia. Noradrenaline was markedly increased even before the operation, and concentrations increased in the halothane group in the course of the operation. There was a linear correlation to time between accident and the beginning of the operation. With regard to endocrine parameters, prompt surgical treatment is beneficial.

Adrenocorticotropic Hormone↗
PubMed1989

Mutations in the genes for mitochondrial RNA polymerase and a second mitochondrial transcription factor of Saccharomyces cerevisiae.

In our previous work (Lisowsky et al. 1987; Lisowsky and Michaelis 1988) we have identified two nuclear pet genes of yeast that are required for mitochondrial transcription. In this report we show that one of these pet mutations, pet-ts798, maps in the RP041 gene encoding mitochondrial RNA polymerase. The temperature-sensitive lesion of mutant pet-ts798 can be suppressed by a second nuclear gene RF1023 (mtf1) when inserted into a high copy number plasmid. Our assumption that mtf1 codes for a 40 kDa mitochondrial transciription factor is supported by the fact that the cloned gene acts as an intergenic suppressor of a temperature-sensitive RNA polymerase mutant. A third nuclear gene (mtf2) for mitochondrial transcription was identified by analysing mutant pet-ts3504. The in vitro transcriptional activity of isolated mutant mitochondria is temperature sensitive suggesting the presence of an altered component of transcription inside mitochondria. The defect was confirmed by studies with a transcriptionally active DNA-protein complex and by testing the DNA-binding ability of mitochondrial proteins.

Alleles↗
PubMed1989

Mitochondrial DNA of Chlamydomonas reinhardtii: the ND4 gene encoding a subunit of NADH dehydrogenase.

The ND4 gene encoding a subunit of respiratory NADH dehydrogenase has been identified on the linear 15.8 kb mitochondrial DNA of Chlamydomonas reinhardtii. The gene maps downstream of ND5. The 1,332 bp nucleotide sequence presented is the first complete reported ND4 sequence from a photoautotrophic organism. The deduced protein of 443 amino acid residues shows 34%, 29% and 27% homology to the protein sequences of Aspergillus amstelodami, Drosophila yakuba and mouse, respectively. ND4 is the fifth and last mitochondrial gene of the NADH dehydrogenase complex on the 15.8 kb mitochondrial genome of C. reinhardtii.

Amino Acid Sequence↗
PubMed1988

A nuclear gene essential for mitochondrial replication suppresses a defect of mitochondrial transcription in Saccharomyces cerevisiae.

A genomic DNA fragment from yeast was isolated by transforming a temperature sensitive pet mutant. This mutant, pet-ts 798, has previously been characterized by its altered mitochondrial transcription apparatus. Subcloning and DNA sequencing of the genomic DNA fragment identified a reading frame responsible for the restoration of the pet-ts phenotype. The reading frame of 1023 bp is transcribed as an RNA of about 1100 nucleotides. The putative protein of 40 kDa possesses a hydrophobic amino-terminus and acidic and basic domains characteristic of recently described transcriptional activators. The inactivation of the functional gene by the introduction of an insertion fragment into the reading frame, leads to a stable pet phenotype. Further analysis of this mutant created by gene disruption makes clear that the respiratory defect is caused by the complete loss of mitochondrial DNA. Experimental evidence is given that the cloned gene acts as an intergenic suppressor of the mutant pet-ts 798. Therefore, the isolated gene represents a new factor involved in the regulation of mitochondrial replication and transcription.

Amino Acid Sequence↗
PubMed1988

[Effect of dyshemoglobinemia (methemoglobinemia and carboxyhemoglobinemia) on accuracy of measurement in pulse oximetry in operations of long duration].

In two groups - eleven patients each - who underwent long lasting surgical procedures, arterial oxygen saturation was measured non-invasively (pulse oximeter) and invasively (CO-oximeter). In addition, total haemoglobin (THb), fractions of haemoglobin (metHb) and bloodgases were monitored. All patients of group I received an epidural anaesthesia via catheter with prilocaine combined with general anaesthesia. In group II a modified neurolept analgesia (balanced) was performed. As expepted we found a prilocaine-induced methaemoglobinaemia (metHb up to 11.6 Vol%) whereas in group II physiological values were not exceeded. Carboxyhaemoglobin up to 4 Vol% was found in the smokers of both groups, which decreased continuously - in contrast to metHb - during hyperoxic ventilation. Comparing the non-invasively and the invasively determined saturations no correlation (r = -0.002) was found in group I. However, a positive correlation (r = 0.652) was obtained in group II. After correction of SaO2 (pulse oximeter) using an adjusted formula a fair correlation (0.613) was found in group I, too. Using this equation for correction the correlation in group II increased to r = 0.824. Because of methodological facts (the pulse oximeter registers only desoxygenated haemoglobin) the arterial oxygen desaturation (O2Hb or fractional saturation) accompanying dyshaemoglobinaemia remains undetectable to the pulse oximeter. In the cases of known or expected dyshaemoglobinaemia pulse oximetry can yield only limited information; fractions of inactive haemoglobin should be measured by other means or accounted for by the given equation for correction (SaO2 corr. = SaO2 pulse oximeter - (COHb + metHb]. Pathophysiological effects of dyshaemoglobinaemia are discussed.

Abdomen↗
PubMed1988

[Behavior of plasma concentrations of prilocaine following intravenous regional anesthesia and their relation to methemoglobinemia].

In a previous investigation we were able to demonstrate quite different methemoglobin levels after axillary plexus blockade on one side and intravenous regional anesthesia (IVRA) on the other using prilocaine (Fig. 1). At that time we tried to explain this observation by prolonged mobilization of the local anesthetic after tourniquet release, causing only minimal stress to the erythrocyte-related reduction system. In order to study prilocaine mobilization after tourniquet release in the upper limb following IVRA, prilocaine and methemoglobin concentrations were measured in 8 patients. All patients received 400 mg prilocaine; IVRA lasted 30 min in all cases. In each patient we inserted an intra-venous line via the cubital vein with its orifice in the region of the venous outflow of the blocked upper extremity (Fig. 2). Simultaneously, blood samples were taken for measurement of plasma prilocaine concentrations in the axillary region of the blocked limb and from the contralateral upper limb. Following tourniquet release, samples were collected at short intervals for 15 min; starting with the 15th min methemoglobin concentrations were also determined for up to 5 h. The results of the outflow and systemic prilocaine concentrations are presented in Figure 3. Remarkable differences in peak prilocaine concentrations (64 micrograms/ml vs 7.9 micrograms/ml after the 1st min) were found during the 3-h study period. The course of methemoglobin formation was similar to that in a group of patients we had studied previously (Fig. 4). Our findings confirm the assumption that the low and plateau-like methemoglobin formation following intravenous regional anesthesia of the arm is the result of delayed prilocaine release.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Conduction↗
PubMed1988

[Tube wall herniation in an Ulmer system as a cause of an intraoperative ventilation disorder].

We report an intraoperative complication caused by nitrous oxide diffusion through the inner layer of a tube of the Ulmer breathing system, which has been developed for ventilation of small children and neonates (Fig. 2a). About 40 min after intubation and mechanical ventilation with oxygen, nitrous oxide, and halothane a sudden rise in PETCO2 was noticed (Fig. 1). Auscultation of both lungs revealed no pathological finding; suction through the endotracheal tube was possible with no indication of endotracheal tube herniation. After reconnection to the ventilator, PETCO2 values again increased. Thorough inspection of the tubes of the Ulmer breathing system revealed a herniation that nearly occluded the lumen (Fig. 2b). After changing the anesthetic system, the operation and anesthesia were continued uneventfully.

Child, Preschool↗
PubMed1987

A nuclear mutation affecting mitochondrial transcription in Saccharomyces cerevisiae.

Mitochondrial transcription was studied in a nuclear temperature-sensitive pet mutant of Saccharomyces cerevisiae. The mitochondrial RNA levels in vivo and the in vitro transcriptional activities of isolated mitochondria were analysed. In comparison to the wild-type an overall reduction of mitochondrial gene expression together with a changed expression pattern was observed for the mutant, indicating a defect in mitochondrial RNA synthesis. These findings were supported by studies with a purified DNA-protein complex from yeast mitochondria. This complex was able to synthesize ribosomal and messenger RNAs in an in vitro system. Proteins from wild-type and mutant transcription complexes were tested for their DNA-binding abilities; one of the proteins identified in the wild type had either lost this ability or was absent in the mutant.

Cell Nucleus↗
PubMed1986

[H-H-H syndrome: a rare disease also relevant in anesthesiology].

We report on a 17-year-old boy with H-H-H-syndrome (hyperornithinaemia, hyperammonaemia, homocitrullinuresis), an inborn disorder of the urea cycle, who had to undergo osteo-synthesis of a fractured upper leg. Pathophysiological aspects of this rare syndrome as well as possible recommendations for the anaesthesiological management are discussed.

Adolescent↗