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Biomedical subjects

C Hein

Publications and source records attributed to C Hein.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of the SLIPA (streamlined liner of the pharynx airway), a single use supraglottic airway device, in 60 anaesthetized patients undergoing minor surgical procedures.

The Streamlined Liner of the Pharyngeal Airway, SLIPA (Hudson RCI) is a new disposable supraglottic airway device that has no inflatable cuff and has features designed to reduce aspiration risk. This study aimed to assess the insertion success and effectiveness of the SLIPA in 60 patients who presented for elective surgery. Ethics committee approval was obtained. Patients were excluded if they were less than 18 years, had not provided written consent or were at risk of pulmonary aspiration. The first 20 SLIPA were inserted by the principal investigator (Group A) followed by another 40 inserted by medical officers and anaesthetists of varying experience (Group B). Twenty-one males and 39 females were recruited into the study. Median time to ventilation was 20.4 seconds in Group A (range 12.9-109) and 24.8 seconds in Group B (range 8.2-82.5). Overall success rate was 100% in Group A and 92.5% in Group B. The lowest recorded SpO2 was 91% in Group B. The incidence of blood and sore throat score >3 (0-10 scale) was 23% and 7% respectively (Groups A and B). Group B reported that use of the device was very easy in 16%, easy in 76%, difficult in 5%, and very difficult in 3%. The SLIPA proved to be a reliable airway providing adequate ventilation in both spontaneous breathing and assisted respiration. Most users found the SLIPA to be easy or very easy to use.

Adult↗
PubMed2002

Atlantoaxial screw fixation for the treatment of isolated and combined unstable jefferson fractures - experiences with 8 patients.

The unstable atlas burst fracture ("Jefferson fracture") is a fracture of the anterior and posterior atlantal arch with rupture of the transverse atlantal ligament and an incongruence of the atlanto-occipital and the atlanto-axial joint facets. The question whether it has to be treated surgically or nonsurgically is still discussed and remains controversial. During the last decade 8 patients with unstable atlas burst fractures were examined and treated in our department. Five of the eight patients were first treated conservatively by external immobilization. Because of continuing instability due to insufficient bony fusion of the atlantal fracture all five patients underwent atlanto-axial transarticular screw fixation and fusion - as described by Magerl - with good results. In all 8 patients a good bony fusion of the atlanto-axial segment was achieved. None of the patients exhibited neurological deficits after surgical treatment. Although immobilization with a halo vest is recommended by most authors, from our view primary transarticular C1-C2 screw fixation has to be discussed as an alternative for unstable atlas burst fractures. Nonsurgical treatment with halo extension always bears the risk of insufficient healing with further instability and a fixated incongruence of the atlanto-occipital and the atlanto-axial joints, leading to arthrosis, immobility and increasing neck pain. After 10 weeks of insufficient immobilization secondary pre- and intra-operative reposition manoeuvres and surgical fixation hardly can reverse this fixated incongruence. Moreover, halo-extension needs an immobilization of the cervical spine for about 10 weeks and more, which is very uncomfortable and leads to further complications especially in elderly patients.

Adult↗
PubMed2002

Occurrence and characterization of peripheral nerve involvement in neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disorder characterized by the occurrence of bilateral vestibular schwannomas, various brain and spinal tumours as well as peripheral nerve tumours, cutaneous tumours and juvenile posterior lenticular opacity. NF2 is caused by mutations in both alleles of a tumour suppressor gene coding for a protein called schwannomin or merlin. It is suggested that the development of NF2 tumours is caused by complete inactivation of the merlin/schwannomin gene. Interestingly, in a NF2 mouse model, peripheral nerve pathology was more frequently described than schwannomas. However, review of the literature shows that patients suffering from NF2 seldom have unexplained clinical features of peripheral nerve lesion unrelated to tumour masses. Single case reports describe sural nerve biopsies, which histologically show onion-bulb-like formations, seemingly originating from Schwann cells. We have conducted a systematic investigation to determine the occurrence and aetiology of peripheral nerve involvement in NF2 patients. We investigated 15 patients with definite NF2 and in 10 of these found electrophysiological evidence of neuropathy. In this study we present the classification of neuropathy, correlation to clinical findings, and histological findings of a sural nerve biopsy. We conclude that peripheral neuropathy, mostly of axonal type, is a common clinical finding in NF2. We hypothesize that the aetiology of this frequent peripheral neuropathy syndrome in NF2 is caused by compression effects of multiple tumourlets, originating along the length of the peripheral nerves on adjacent nerve fibres, by local influences of the endoneurial pathological cells on adjacent nerve fibres and/or the inability of these cells to properly adhere to, or ensheath, the axon.

Adult↗
PubMed2001

Spinal neurofibromatosis without café-au-lait macules in two families with null mutations of the NF1 gene.

Spinal neurofibromatosis (SNF) is considered to be an alternative form of neurofibromatosis, showing multiple spinal tumors and café-au-lait macules. Involvement of the neurofibromatosis type 1 (NF1) locus has been demonstrated, by linkage analysis, for three families with SNF. In one of them, a cosegregating frameshift mutation in exon 46 of the NF1 gene was identified. In the present study, we report four individuals from two families who carry NF1 null mutations that would be expected to cause NF1. Three patients have multiple spinal tumors and no café-au-lait macules, and the fourth has no clinical signs of NF1. In the first family, a missense mutation (Leu2067Pro) in NF1 exon 33 was found, and, in the second, a splice-site mutation (IVS31-5A-->G) enlarging exon 32 by 4 bp at the 5' end was found. The latter mutation has also been observed in an unrelated patient with classical NF1. Both NF1 mutations cause a reduction in neurofibromin of approximately 50%, with no truncated protein present in the cells. This demonstrates that typical NF1 null mutations can result in a phenotype that is distinct from classical NF1, showing only a small spectrum of the NF1 symptoms, such as multiple spinal tumors, but not completely fitting the current clinical criteria for SNF. We speculate that this phenotype is caused by an unknown modifying gene that compensates for some, but not all, of the effects caused by neurofibromin deficiency.

Adolescent↗
PubMed2001

Glutamate transporter expression in astrocytes of the rat dentate gyrus following lesion of the entorhinal cortex.

The glutamate transporters GLT-1 and GLAST localized in astrocytes are essential in limiting transmitter signalling and restricting harmful receptor overstimulation. To show changes in the expression of both transporters following lesion of the entorhinal cortex (and degeneration of the glutamatergic tractus perforans), quantitative microscopic in situ hybridization (ISH) using alkaline-phosphatase-labelled oligonucleotide probes was applied to the outer molecular layer of the hippocampal dentate gyrus of rats (termination field of the tractus perforans). Four groups of rats were studied: sham-operated controls, and animals 3, 14 and 60 days following unilateral electrolytic lesion of the entorhinal cortex. The postlesional shrinkage of the terminal field of the perforant path, ipsilateral to the lesion side, was determined and considered in the evaluation of quantitative ISH data. Statistical analysis revealed that ipsilateral to the lesion side there was a significant decrease of the GLT-1 mRNA at every postlesional time-point and of the GLAST mRNA at 14 and 60 days postlesion. The maximal decrease was approximately 45% for GLT-1 and approximately 35% for GLAST. In the terminal field of the perforant path contralateral to the lesion side, no significant changes of ISH labelling were measured. The results were complemented by immunocytochemical data achieved using antibodies against synthetic GLT-1 and GLAST peptides. In accordance with ISH results, there was an obvious decrease of GLT-1 and GLAST immunostaining in the terminal field of the perforant path ipsilateral to the lesion side. From these data we conclude that, following a lesioning of the entorhinal cortex, the loss of glutamatergic synapses in the terminal field of the perforant path resulted in a strong downregulation of glutamate transporters in astrocytes. The decrease of synaptically released glutamate or of other neuronal factors could be involved in this downregulation.

ATP-Binding Cassette Transporters↗
PubMed1997

A C-terminal di-leucine motif and nearby sequences are required for NH4(+)-induced inactivation and degradation of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae.

The general amino acid permease, Gap1, of Saccharomyces cerevisiae is very active in cells grown on proline as the sole nitrogen source. Adding NH4+ to the medium triggers inactivation and degradation of the permease via a regulatory process involving Npi1p/Rsp5p, a ubiquitin-protein ligase. In this study, we describe several mutations affecting the C-terminal region of Gap1p that render the permease resistant to NH4(+)-induced inactivation. An in vivo isolated mutation (gap1pgr) causes a single Glu-->Lys substitution in an amino acid context similar to the DXKSS sequence involved in ubiquitination and endocytosis of the yeast alpha-factor receptor, Ste2p. Another replacement, substitution of two alanines for a di-leucine motif, likewise protects the Gap1 permease against NH4(+)-induced inactivation. In mammalian cells, such a motif is involved in the internalization of several cell-surface proteins. These data provide the first indication that a di-leucine motif influences the function of a plasma membrane protein in yeast. Mutagenesis of a putative phosphorylation site upstream from the di-leucine motif altered neither the activity nor the regulation of the permease. In contrast, deletion of the last eleven amino acids of Gap1p, a region conserved in other amino acid permeases, conferred resistance to NH4+ inactivation. Although the C-terminal region of Gap1p plays an important role in nitrogen control of activity, it was not sufficient to confer this regulation to two NH4(+)-insensitive permeases, namely the arginine (Can1p) and uracil (Fur4p) permeases.

Amino Acid Sequence↗
PubMed1995

Clonal hematopoiesis as defined by polymorphic X-linked loci occurs infrequently in aplastic anemia.

We evaluated the methylation status of the X-linked gene phosphoglycerate kinase (PGK1) and the DXS 255 locus detected by probe M27 beta to study clonality in acquired aplastic anemia (AA). A total of 30 females were suitable for clonal analysis of peripheral blood polymorphonuclear cells (PMN) and mononuclear cells using a polymerase chain reaction-based procedure in 24 patients and Southern blotting in 9. Overall, 10 of 30 patients exhibited an imbalanced X-inactivation pattern. However, in 4 patients, analysis of constitutional DNA suggested a skewed methylation pattern and 2 further cases had to be excluded because of the lack of an appropriate control. A truly clonal pattern was thus established in 4 of 30 (13%) patients. In 7 patients who later developed clonal disorders of hematopoiesis, X-inactivation analysis did not predict this event in any case. In patients with a paroxysmal nocturnal hemoglobinuria phenotype, there was no correlation between the proportion of phosphatidylinositol glycan anchored protein (PIG-AP)-deficient blood cells and the corresponding X-inactivation pattern. X-inactivation analysis detected clonal hematopoiesis in only 3 of 10 patients with a deficiency in PIG-AP in the cell population under study, but sorting of nucleated cells on the basis of PIG-AP expression showed the clonal nature of PIG-AP-deficient cells. We conclude that the majority of patients with AA show polyclonal hematopoiesis using X-linked clonal analysis, but that minor clonal populations, such as PIG-AP-deficient cells, may not be detected unless sorted cell populations are separately analyzed.

Adolescent↗
PubMed1995

Two mutually exclusive regulatory systems inhibit UASGATA, a cluster of 5'-GAT(A/T)A-3' upstream from the UGA4 gene of Saccharomyces cerevisiae.

The S. cerevisiae Uga43(Dal80) protein down-regulates the expression of multiple nitrogen pathway genes. It contains a zinc-finger motif similar to the DNA-binding domain of the vertebrate GATA family of transcription factors; this domain is known to direct binding to 5'-GATA-3' core sequences. The inducible UGA4 gene, which encodes the specific gamma-aminobutyrate permease, undergoes strong repression by Uga43p. This study shows that the 5' region of UGA4 contains a UAS element made of four directly repeated 5'-CGAT(A/T) AG-3' sequences. This element, called UASGATA, can potentially confer to the UGA4 gene high-level expression in the absence of inducer, but this potential activity is inhibited by two distinct repression systems. One system is Uga43p-dependent; it operates in cells grown on a poor nitrogen source. The other is the nitrogen repression system, which relies on Ure2p and glutamine and operates when a good nitrogen source is present. Nitrogen repression also blocks the synthesis of Uga43p, making the two repression systems mutually exclusive. Previous studies have shown that expression supported by 5'-GATA-3'-containing UAS elements requires Gln3p, another global nitrogen regulatory factor containing a GATA zinc-finger domain. Although Gln3p contributes to UASGATA activity, evidence suggests that a second factor can potentially direct expression through UASGATA. Expression conferred by this putative factor is subject to both Uga43p- and Ure2p-mediated repression. The role of UASGATA in the expression of the UGA4 gene is discussed in relation to its sensitivity to the two distinct repression systems.

Amino Acid Sequence↗
PubMed1995

NPl1, an essential yeast gene involved in induced degradation of Gap1 and Fur4 permeases, encodes the Rsp5 ubiquitin-protein ligase.

When yeast cells growing on a poor nitrogen source are supplied with NH4+ ions, several nitrogen permeases including the general amino acid permease (Gap1p) are rapidly and completely inactivated. This report shows that inactivation by NH4+ of the Gap1 permease is accompanied by its degradation. A functional NPl1 gene product is required for both inactivation and degradation of Gap1p. Molecular analysis of the NPl1 gene showed that it is identical to RSP5. The RSP5 product is a ubiquitin-protein ligase (E3 enzyme) whose physiological function was, however, unknown. Its C-terminal region is very similar to that of other members of the E6-AP-like family of ubiquitin-protein ligases. Its N-terminal region contains a single C2 domain that may be a Ca(2+)-dependent phospholipid interaction motif, followed by several copies of a recently identified domain called WW(P). The Npi1/Rsp5 protein has a homologue both in humans and in mice, the latter being involved in brain development. Stress-induced degradation of the uracil permease (Fur4p), a process in which ubiquitin is probably involved, was also found to require a functional NPl1/RSP5 product. Chromosomal deletion of NPl1/RSP5 showed that this gene is essential for cell viability. In the viable npi1/rsp5 strain, expression of NPl1/RSP5 is reduced as a result of insertion of a Ty1 element in its 5' region. Our results show that the Npi1/Rsp5 ubiquitin-protein ligase participates in induced degradation of at least two permeases, Gap1p and Fur4p, and probably also other proteins.

Amino Acid Sequence↗
PubMed1994

Complete DNA sequence of yeast chromosome II.

In the framework of the EU genome-sequencing programmes, the complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome II (807 188 bp) has been determined. At present, this is the largest eukaryotic chromosome entirely sequenced. A total of 410 open reading frames (ORFs) were identified, covering 72% of the sequence. Similarity searches revealed that 124 ORFs (30%) correspond to genes of known function, 51 ORFs (12.5%) appear to be homologues of genes whose functions are known, 52 others (12.5%) have homologues the functions of which are not well defined and another 33 of the novel putative genes (8%) exhibit a degree of similarity which is insufficient to confidently assign function. Of the genes on chromosome II, 37-45% are thus of unpredicted function. Among the novel putative genes, we found several that are related to genes that perform differentiated functions in multicellular organisms of are involved in malignancy. In addition to a compact arrangement of potential protein coding sequences, the analysis of this chromosome confirmed general chromosome patterns but also revealed particular novel features of chromosomal organization. Alternating regional variations in average base composition correlate with variations in local gene density along chromosome II, as observed in chromosomes XI and III. We propose that functional ARS elements are preferably located in the AT-rich regions that have a spacing of approximately 110 kb. Similarly, the 13 tRNA genes and the three Ty elements of chromosome II are found in AT-rich regions. In chromosome II, the distribution of coding sequences between the two strands is biased, with a ratio of 1.3:1. An interesting aspect regarding the evolution of the eukaryotic genome is the finding that chromosome II has a high degree of internal genetic redundancy, amounting to 16% of the coding capacity.

Base Composition↗
PubMed1993

Cloning and expression of the UGA4 gene coding for the inducible GABA-specific transport protein of Saccharomyces cerevisiae.

Transport of 4-aminobutyric acid (GABA) in Saccharomyces cerevisiae is mediated by three transport systems: the general amino acid permease (GAP1 gene), the proline permease (PUT4 gene), and a specific GABA permease (UGA4 gene) which is induced in the presence of GABA. The UGA4 gene encoding the inducible GABA-specific transporter was cloned and sequenced and its expression analyzed. The predicted amino acid sequence shows that UGA4 encodes a 62 kDa protein having 9-12 putative membrane-spanning regions. The predicted UGA4 protein shares significant sequence similarity with the yeast choline transporter (CTR gene), exhibiting but limited similarity to the previously reported GABA transporters, i.e. the yeast GAP1 and PUT4 permeases and the rat brain GAT-1 transporter. Induction of UGA4 in the presence of GABA is exerted at the level of UGA4 mRNA accumulation, most probably at the level of transcription itself. This induction is conferred by the 5' flanking region and requires the integrity of two positive regulatory proteins, the inducer-specific factor UGA3 and the pleiotropic factor UGA35/DURL/DAL81. In the absence of the pleiotropic UGA43/DAL80 repressor, UGA4 is constitutively expressed at high level.

Amino Acid Sequence↗
PubMed1990

[The enamel surface quality after interproximal stripping--a scanning electron microscopic assessment of different polishing procedures].

The surface features of stripped human enamel were studied with the scanning electron microscope. The efficiency of rotating diamond and polishing discs was compared with that of diamond and polishing strips in a newly developed handpiece. Interproximal stripping with fine and superfine grit diamond coated discs and strips created furrows which were 10 microns in width. At the interface between treated and untreated enamel no hard tissue damage could be observed. Under in vitro conditions the furrows resulting from stripping were almost totally eliminated by using aluminum oxide coated strips or discs in automatically driven handpieces. After 60 s of polishing with each polishing strip/disc the treated enamel surfaces were nearly smooth. Only a few isolated furrows of 1 to maximum 3 microns were detected. As a result, we can state that it is possible to produce surfaces which are smoother than untreated natural enamel with the rotating or the oscillating polishing procedure.

Dental Enamel↗
PubMed1982

Addition of fiber (wheat bran, bassorin) to the standard food does not influence biliary lipid composition in piglets.

The influence of an additional fiber diet on biliary lipid composition of gallbladder bile was studied in 12 piglets. In addition to the standard feed wheat bran was given for 6 weeks and bassorin for 2 weeks to each of four piglets. A group of four piglets served as controls. Gallbladder bile was obtained by ultrasonically guided puncture of the gallbladder. The results showed no significant alteration of bile acids, lipid composition, and lithogenity of bile for either of the diets. These findings are interpreted in that way that the normally high basic fiber content of the food of piglets does not allow a further decrease of the lithogenic index by addition of wheat bran or bassorin. This conclusion would mean that the basic fiber diet should be known before therapeutic trials with fiber diets are planned or interpreted.

Animals↗