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K Bauer

Publications and source records attributed to K Bauer.

At least 55 records · Page 3Linked to original sources
PubMed1999

Human TRH-degrading ectoenzyme cDNA cloning, functional expression, genomic structure and chromosomal assignment.

Thyrotropin-Releasing Hormone (TRH) is an important extracellular signal substance that acts as a stimulator of hormone secretion from adenohypophyseal target cells and fulfills many criteria for the function of a neuromodulator/neurotransmitter within the central and peripheral nervous systems. The inactivation of TRH-signals is catalysed by a highly specific ectoenzyme. Here, we characterize the human TRH-degrading ectoenzyme (TRH-DE) by primary sequence, functional expression, genomic structure and chromosomal assignment. By screening a cDNA-library constructed from human lung, 5.7 kb of cDNA were identified. The longest open reading frame predicts a type II integral membrane protein of 117 kDa. The extracellular domain contains the HEXXH + E motif that is characteristic of a certain family of Zn-dependent aminopeptidases. Within this family, the sequences of human and rat TRH-DE reveal an unusual high degree of conservation (96% identical residues). Specific enzymatic activity was observed after transfecting COS-7 cells with human TRH-DE cDNA yielding a Km for TRH hydrolysis of 29.7 microM. Northern blot analysis demonstrated a restricted tissue distribution with highest transcript levels in the brain. Using fluorescent in situ hybridization with the cDNA and a genomic lambda clone, respectively, we localized the TRH-DE gene to the long arm of human chromosome 12. Five independent P1 artificial chromosome clones were required to span the complete cDNA sequence and revealed that it is distributed on 19 exons. Interspecies Southern analysis suggests that the gene is present as a single copy in human, monkey, rat, mouse, dog, bovine, rabbit and chicken DNA. All of these data further the notion that the TRH-DE is not an ordinary enzyme but a specific neuropeptidase that has been highly conserved among species.

Amino Acid Sequence↗
PubMed1999

Effects of method, duration, and sleep stage on rebounds from sleep deprivation in the rat.

Total sleep deprivation (TSD) of rats for 24 hours or less by continually enforced locomotion has consistently produced subsequent rebounds of slow-wave or high-amplitude EEG activity in NREM sleep, which has contributed to the widely held view that this EEG activity reflects particularly "intense" or restorative sleep. These rebounds usually have been accompanied by substantial rebounds of REM sleep. In contrast, chronic TSD (2 weeks or longer) by the disk-over-water (DOW) method has produced only huge, long-lasting rebounds of REM sleep with no rebound of high-amplitude NREM sleep. To evaluate whether the different rebounds result from different methods or from different lengths of deprivation, rats were subjected to 24-hour TSD by the DOW method. Rebounds included increases in high-amplitude and slow-wave activity; i.e., the methods produced similar rebound patterns following short-term TSD. (Chronic TSD by continually enforced locomotion would be strategically difficult and severely confounded with motor fatigue.) Rats subjected to DOW-TSD for 4 days, well before the development of severe TSD symptoms, showed primarily REM sleep rebounds. Rats subjected to 1 day of selective REM sleep deprivation, but not their closely yoked control rats, showed large, significant REM sleep rebounds, which evidently were not induced by the stress of the deprivation method per se. The combined findings prompted reexamination of published evidence relevant to "sleep intensity," including "negative rebounds," rebounds in other species, the effects of stress and fatigue, depth of sleep indicators, and extended sleep. The review points out pitfalls in the designation of any specific pattern as intense sleep.

Animals↗
PubMed1999

The peptide transporter PepT2 is expressed in rat brain and mediates the accumulation of the fluorescent dipeptide derivative beta-Ala-Lys-Nepsilon-AMCA in astrocytes.

We describe the synthesis of a fluorescent dipeptide derivative, beta-Ala-Lys-Nepsilon-AMCA, which could be used as an excellent reporter molecule for studying the oligopeptide transport system in brain cell cultures. Fluorescence microscopic and immunocytochemical studies revealed that the reporter peptide specifically accumulated in astrocytes (type I and II) and O-2A progenitor cells but not in neurons or differentiated oligodendrocytes. In astroglia-rich cell culture the dipeptide derivative is taken up in unmetabolized form by an energy dependent, saturable process with apparent kinetic constants of KM = 28 microM and Vmax = 6 nmol x h(-1) x mg protein(-1) at pH 7.2. Competition studies revealed that the accumulation of beta-Ala-Lys-Nepsilon-AMCA is strongly inhibited by dipeptides and pseudopeptides such as bestatin, arphamenine A and B. The biochemical data indicated that the properties of this high-affinity oligopeptide carrier closely resemble those of the renal peptide transport system PepT2 and Northern blot analysis demonstrated that PepT2 mRNAis expressed in glial but not in neuronal cell cultures. In situ hybridization histochemistry also revealed a non-neuronal localization of PepT2 transcripts and a diffuse, widespread distribution of PepT2 signals throughout the entire rat brain. The selective accumulation of the fluorescent reporter molecule by brain cells under viable conditions may provide a useful tool for studying peptide uptake systems and other aspects of astroglial physiology.

Animals↗
PubMed1999

Pulmonary embolism and myocardial hypoxia during extracorporeal membrane oxygenation.

The treatment of a newborn with severe meconium aspiration by venoarterial extracorporeal membrane oxygenation (ECMO) was complicated by myocardial hypoxia with a marked decrease of myocardial contractility. The onset of the cardiac hypoxia was related to a pulmonary artery embolus. The origin of the embolus was a deep femoral vein thrombosis, caused by a central vein catheter, which was inserted 1 day before ECMO by venous cutdown. The possible pathophysiology of myocardial hypoxia in this patient is discussed, especially with regard to myocardial perfusion, supporting the hypothesis of coronary perfusion occuring with blood from the left ventricle and not from the arterial cannula in the aorta.

Catheterization, Central Venous↗
PubMed1999

mtDNA analysis of Nile River Valley populations: A genetic corridor or a barrier to migration?

To assess the extent to which the Nile River Valley has been a corridor for human migrations between Egypt and sub-Saharan Africa, we analyzed mtDNA variation in 224 individuals from various locations along the river. Sequences of the first hypervariable segment (HV1) of the mtDNA control region and a polymorphic HpaI site at position 3592 allowed us to designate each mtDNA as being of "northern" or "southern" affiliation. Proportions of northern and southern mtDNA differed significantly between Egypt, Nubia, and the southern Sudan. At slowly evolving sites within HV1, northern-mtDNA diversity was highest in Egypt and lowest in the southern Sudan, and southern-mtDNA diversity was highest in the southern Sudan and lowest in Egypt, indicating that migrations had occurred bidirectionally along the Nile River Valley. Egypt and Nubia have low and similar amounts of divergence for both mtDNA types, which is consistent with historical evidence for long-term interactions between Egypt and Nubia. Spatial autocorrelation analysis demonstrates a smooth gradient of decreasing genetic similarity of mtDNA types as geographic distance between sampling localities increases, strongly suggesting gene flow along the Nile, with no evident barriers. We conclude that these migrations probably occurred within the past few hundred to few thousand years and that the migration from north to south was either earlier or lesser in the extent of gene flow than the migration from south to north.

DNA Mutational Analysis↗
PubMed1999

Thyrotropin-releasing hormone (TRH), a signal peptide of the central nervous system.

Thyrotropin-Releasing Hormone (TRH; pyroGlu-His-Pro-NH2), originally isolated as a hypothalamic neuropeptide hormone, most likely acts also as a neuromodulator and/or neurotransmitter in the central nervous system (CNS). This interpretation is supported by the identification of a peptidase localized on the surface of neuronal cells which has been termed TRH-degrading ectoenzyme (TRH-DE) since it selectively inactivates TRH. Vice versa it also holds true that TRH is selectively inactivated only by TRH-DE and thus, this enzyme might be considered to be the terminator of TRH signals. In situ-hybridization histochemistry was used to study the TRHergic communication system by analyzing the gene expression of TRH-DE in relation to TRH and to the TRH receptors (TRH-R1 and TRH-R2). TRH mRNA is highly expressed in "thyrotropic" hypothalamic regions and in some selected brain areas. For TRH-R1 and TRH-R2, an almost exclusive mRNA distribution pattern was noticed in many brain regions. Interestingly, a widespread distribution of TRH-DE predominantly in neo- and allocortical regions was observed essentially overlapping the distribution patterns of TRH-R1 and TRH-R2. These data support the hypothesis that TRH-DE is important in the TRH-mediated modulation of sensory, locomotor and cognitive functions of the CNS and could be considered to be a marker to map TRHergic pathways.

Gene Expression↗
PubMed1998

Tandem immobilized metal-ion affinity chromatography/immunoaffinity purification of His-tagged proteins--evaluation of two anti-His-tag monoclonal antibodies.

A tag comprising four to six histidines genetically fused to the protein of interest (His-tag) has been widely used to purify proteins by immobilized metal-ion affinity chromatography (IMAC). Here we report the utilization of the same tag twice in series, first for IMAC and subsequently for immunoaffinity purification. Both steps are based on completely different physical principles and can therefore remove different contaminants. Two anti-His-tag antibodies (3D5 and PentaHis) were characterized for their binding and elution properties using the BIAcore surface plasmon resonance biosensor. The dissociation constant of the PentaHis antibody was determined to be 1 x 10(-8) M and for the 3D5 antibody 3.4 x 10(-7) M at pH 7.4. Imidazole in the sample did interfere with binding, whereas chelating agents such as EDTA and high salt did not. The antibody 3D5 was coupled to a column matrix and used for a coupled two-step purification, in which the IMAC column is eluted with EDTA and the eluent is loaded directly on the immunoaffinity column. This method may constitute a very general procedure to purify proteins to near homogeneity without the need to tailor conditions individually, and it may thus be very attractive for high-throughput screening programs and for developing general protocols for clinical grade material.

Amino Acid Sequence↗
PubMed1998

Postnatal body weight curves for infants below 1000 g birth weight receiving early enteral and parenteral nutrition.

UNLABELLED: No body weight curves are available for preterm infants < 1000 g birth weight receiving early enteral and parenteral nutrition. Postnatal weight changes of 136 infants with a birth weight < 1000 g were analysed retrospectively. Body weight curves for the first 30 days of life were generated for five separate birth weight groups (430-599 g, 600-699 g, 700-799 g, 800-899 g, 900-999 g). All infants had received intravenous glucose and amino acids from day 1 and intravenous lipids from day 2. Enteral feeding was started on day 1. Thus caloric intake (+/-SD) was advanced to 384+/-46 kJ/kg per day (92+/-11 kcal/kg/day) in the 1st week of life. In 136 preterm infants mean postnatal weight loss was 10.1%+/-4.6% of birth weight, birth weight was regained at a mean postnatal age of 11+/-3.7 days, but significantly earlier (7.8+/-3.5 days) in the lowest compared to the highest weight group. Mean subsequent weight gain was 15.7+/-7.2 g/ kg per day. This was accomplished by exclusive enteral nutrition from day 20 (median). CONCLUSION: Our body weight curves are more adequate to evaluate growth of preterm infants than older published reference values because they are based on infants treated according to current nutritional standards.

Enteral Nutrition↗
PubMed1998

Critical thinking's role in perioperative patient safety outcomes.

Despite education, training, tools, and standards, patient safety issues continue to be of concern when it comes to perioperative care. The problem of intraoperative injuries, therefore, may lie in perioperative nurses' implementation of safety measures that require critical thinking. This qualitative study lends insight into the critical thinking or decision-making processes of nurses who implement these perioperative safety measures. Findings from this data analysis have led to perioperative recommendations that may enhance patient safety outcomes.

Humans↗
PubMed1998

Region-specific expression of thyrotrophin-releasing hormone-degrading ectoenzyme in the rat central nervous system and pituitary gland.

Thyrotrophin-releasing hormone (TRH), a hypothalamic neuropeptide hormone and a putative neuromodulator/ neurotransmitter in the central nervous system is inactivated by the TRH-degrading ectoenzyme (TRH-DE), a TRH-specific metallopeptidase localized on the surface of neuronal brain cells in culture and on lactotrophic cells of the pituitary. After succeeding in cloning the cDNA of TRH-DE we now report on the cellular distribution pattern of this enzyme in rat brain, spinal cord and pituitary gland using in situ hybridization histochemistry. In the pituitary, TRH-DE mRNA was found both in the anterior and the neural lobe but not in the intermediate lobe. After treatment with triiodothyronine (T3) a dramatic increase in the mRNA levels of the TRH-DE and a decrease in the intensity of the TRH receptor could be observed in the anterior lobe of the pituitary. In brain, TRH-DE transcripts were predominantly found in neo- and allocortical regions with strongest signals in the olfactory bulb, the piriform cortex, the cerebral cortex, the granular layer of the cerebellar cortex and the pyramidal cells of the Ammon's horn. In the diencephalon, the highest TRH-DE mRNA levels were observed in the medial habenulae followed by several hypothalamic subregions. In the mesencephalon and brainstem, moderate signals were present in the superior colliculi, substantia nigra, dorsal raphe and in the periolivar region. In the spinal cord, TRH-DE mRNA positive neurons were present in all layers. The very distinct distribution of TRH-DE in the brain and the hormonal regulation of the adenohypophyseal enzyme support the concept that this peptidase serves very specialized functions.

Aminopeptidases↗
PubMed1998

The thyrotropin-releasing hormone-degrading ectoenzyme: the third element of the thyrotropin-releasing hormone-signaling system.

The peptidergic signal substance thyrotropin-releasing hormone (TRH) is inactivated by the TRH-degrading ectoenzyme (TRH-DE), a peptidase that exhibits an extraordinary high degree of substrate specificity and other unusual characteristics. There is no other ectopeptidase known capable of degrading this tripeptideamide, and vice versa, TRH is the only known substrate of this unique enzyme. Thus, studies on this enzyme may reveal new aspects on the function of the TRH signaling system. After succeeding in purifying this enzyme to homogeneity and cloning the cDNA encoding rat TRH-DE, molecular tools became available to study the expression of this enzyme by Northern blot analysis and in situ hybridization histochemistry. The stringent and tissue-specific regulation of the adenohypophyseal TRH-DE by estradiol and thyroid hormones strongly suggests that this enzyme may act as a regulatory element modulating pituitary hormone secretion. In brain, the expression of TRH-DE is not influenced by peripheral hormones but the distinct distribution pattern, and the high activities support the concept that in this tissue TRH-DE may act as a terminator of TRH signals.

Aminopeptidases↗
PubMed1998

Immunogenetic evidence for the phylogenetic sister group relationship of dogs and bears (Mammalia, Carnivora: Canidae and Crsidae). a comparative determinant analysis of carnivoran albumin, c3 complement and immunoglobulin micro-chain.

Thirty-seven antigenic determinants were identified in the albumins, the immunoglobulin micro- and IgG(Fc) chains, and the C3 proteins of 51 carnivoran (sub)species from 31 genera, and in 12 noncarnivoran mammals. In addition to 19 determinants plesiomorphic for Carnivora as an order, 18 synapomorphic epitopes of carnivoran families revealed nine phylogenetic reaction groups: (1) canids, (2) ursids, (3) the racoon, (4) the Weddell seal, (5) the lesser panda, (6) the harbour seal, (7) mustelids, (8) viverrids and hyaenas, and (9) felids. These data identify Canoidea (Canidae, Ursidae, Phocidae, Procyonidae, Ailuridae, Mustelidae) and Feloidea (Viverridae, Hyaenidae, Felidae) as two fundamentally differentiated lineages of Carnivora, and confirm the inclusion of seals among the former. The Ursidae are the sister group of the Canidae. The antigenic determinants in the studied proteins do not subdivide the Canidae, Ursidae and Felidae into immunologically differentiated lineages.

Albumins↗
PubMed1998

Effects of gestational and postnatal age on body temperature, oxygen consumption, and activity during early skin-to-skin contact between preterm infants of 25-30-week gestation and their mothers.

Temporary skin-to-skin contact between preterm infant and the mother is increasingly used in neonatal medicine to promote bonding. It is not known at which gestational age (GA) and postnatal age skin-to-skin contact outside the incubator is a sufficiently warm environment and is tolerated by preterm infants without a decrease in body temperature, oxygen consumption (VO2) increase, or unrest. We conducted a prospective clinical study of 27 spontaneously breathing preterm infants of 25-30-wk GA. Rectal temperature (Trecta), VO2 (indirect calorimetry), and activity were continuously measured in the incubator (60 min), during skin-to-skin contact (60 min), and back in the incubator (60 min) in wk 1 and 2 of life. In wk 1 the change in Trectal during skin-to-skin contact was related to GA (r=0.585, p=0.0027): infants of 25-27-wk GA lost heat during skin-to-skin contact, whereas infants of 28-30 wk gained heat and their mean Trectal during skin-to-skin contact was 0.3 degrees C higher than before (p < 0.01). No significant changes of VO2 or activity occurred. In wk 2 the infants' VO2 was higher than in wk 1, but VO2 during skin-to-skin contact was the same as in the incubator. Only small fluctuations in Trectal occurred. In wk 2 all infants slept more during skin-to-skin contact than in the incubator (p < 0.02). We conclude that, for preterm infants of 28-30-wk GA, skin-to-skin contact was a sufficiently warm environment as early as postnatal wk 1. For infants of 25-27-wk GA skin-to-skin contact should be postponed until wk 2 of life, when their body temperature remains stable and they are more quiet during skin-to-skin contact than in the incubator.

Adult↗
PubMed1998

Restriction digest PCR (RD-PCR) for the analysis of gene mutations. Application to Ki-ras.

The Kirsten-ras (onco)gene codes for a GTP-binding membrane protein that is involved in signal transduction. Activated ras triggers a cascade of protein-phosphorylations that ultimately lead to cell proliferation. Ras-mutations are the main cause for adenocarcinomas of the pancreas besides some mutations in the tumor suppressor gene p53 and the c-erbB-2 oncogene. The site of ras mutations in pancreatic cancer is restricted to codon 12 that normally encodes a glycine. For analysis of codon-12 mutations, DNA is extracted from cells in pancreatic fluid and amplified by PCR. Because most of these cells originate from normal tissue with only a few tumor cells in the fluid, "enrichment PCR" must be utilized: In a first round of the PCR, ras sequences from all cells are amplified. By utilizing an appropriate restriction enzyme, wild-type sequences can be digested and the remaining fragments containing mutated sequences be amplified again. An artificial restriction site must be introduced by the 5'primer (...GGA CCT GGT...) for an enzyme (BstNI) (5'CC!WGG 3') to differentiate between wild-type sequence (...GGA GCT GGT...) (during amplification, the G is replaced by a C) and mutated sequences (_...GGA GCT (GTT), (CGT), (CCT), etc.). The necessary manipulations pose a considerable risk for contamination for the second round of the PCR procedure. Therefore, we considered whether it would be feasible to perform the restriction digest simultaneously with the first PCR reaction, and avoiding the second round altogether. The results of our experiments demonstrate that one tumor cell in 1000 normal cells can be determined readily, paralleling the results with the original two step-assay. The restriction enzyme used to enrich mutated sequences is stable long enough to be included into the PCR procedure. By this, wild-type sequence amplicons are digested while they are formed and mutated sequences can be enriched selectively.

Base Sequence↗
PubMed1997

Foot- and-mouth disease as zoonosis.

Man's susceptibility to the virus of foot- and-mouth disease (FMD) was debated for many years. Today the virus has been isolated and typed (type O, followed by type C and rarely A) in more than 40 human cases. So no doubt remains that FMD is a zoonosis. Considering the high incidence of the disease (in animals) in the past and in some areas up to date, occurrence in man is quite rare. In the past when FMD was endemic in Central Europe many cases of diseases in man showing vesicles in the mouth or on the hands and feet were called FMD. The first suggestion of a human infection with FMD was reported in 1695 by Valentini in Germany [7]. All reports before 1897, the year of the discovery of the virus of FMD by Loeffler and Frosch [2], were not of course confirmed either by isolation of the virus or by identification of immunoglobulins after infection. Nevertheless the successful self-infection reported by Hertwig in 1834 most likely seems to have been FMD in man: each of three veterinarians drank 250 ml of milk from infected cows on four consecutive days. The three men developed clinical manifestations. The diseases most often confused with FMD are infections with several viruses of the Coxsackie A group (this infection is referred to as "hand and mouth disease"), herpes simplex and sometimes vesicular stomatitis. Beginning in 1921 up to 1969 at least 38 papers were published, which described clinically manifest FMD in man in more than 40 proven cases. One further reported described an asymptomatic infection with FMD in man [10]. Criteria for establishing a diagnosis of FMD in man are the isolation of the virus from the patient and/or identification of specific antibodies after infection. Laboratory tests for diagnosis of human FMD are the same as for animals. Proven cases of FMD in man have occurred in several countries in Europe, Africa and South America. The type of virus most frequently isolated man is type O followed by type C and rarely A. The incubation period in man, although somewhat variable, has not been found to be less than two days and rarely more than six days.

Animals↗
PubMed1997

Serum levels of soluble CD44 variant isoforms are elevated in rheumatoid arthritis.

Serum levels of soluble CD44 variant proteins including sequences encoded by exon v5 and exon v6 (sCD44v5, sCD44v6) were determined in patients with inflammatory rheumatic diseases: 56 with rheumatoid arthritis (RA+) and 31 with miscellaneous inflammatory rheumatic diseases (MIRD). There were very significantly higher serum levels of sCD44v5 and sCD44v6 in patients with RA+ than in those with MIRD (RA+ to MIRD: sCD44v5: 81 +/- 54 ng/ml to 33 +/- 13 ng/ml; sCD44v6: 237 +/- 124 ng/ml to 166 +/- 53 ng/ml; both P << 0.001). In RA+ elevated serum levels of sCD44v5 were correlated with the inflammatory activity of disease. In 17 patients with RA+ three or four follow-up measurements of sCD44v5 were performed within 6 months. The development of sCD44v5 serum levels reflected the clinical course of disease in the patients investigated.

Adult↗
PubMed1997

Correction factors of 3H-beta-self-absorption for quantitative autoradiography of different cell types in the brain of pre- and postnatal mice.

Interferometric and morphometric studies were performed on seven types of brain cells of deparaffinised and Feulgen-stained brain sections of pre- and postnatal mice in order to find out to what extent 3H-beta-self-absorption factors (c.f.s) of karyoplasm and perikaryal cytoplasm change as the animals' age increases. This is important when comparing grain numbers of different cell types among mice of different age in quantitative autoradiographic studies after application of tritium-labelled substances. While optical path differences (o.p.d.s) of euchromatin and cytoplasm decreased in large neurons postnatally, heterochromatic o.p.d.s remained more or less unchanged. The fraction of euchromatin (fEu) and heterochromatin (fHe) changed specifically in relation to cell type with increasing age, i.e. mostly heterochromatin increased postnatally. Within a given age, c.f.s, calculated from o.p.d.s, fEu and fHe, varied up to a maximum factor of 2.16 for karyoplasm and a factor of 1.19 for cytoplasm between different cell types. A significant decrease of c.f.s postnatally was found only for the cytoplasm of cortical and hippocampal pyramidal cells and for cerebellar Purkinje cells. The c.f.s of karyoplasm remained more or less unchanged with increasing age of the mice. The calculation of relative c.f.s makes these c.f.s applicable for every other autoradiographic study using 3H-labelled substances.

Animals↗