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Biomedical subjects

K Bauer

Publications and source records attributed to K Bauer.

At least 91 records · Page 5Linked to original sources
PubMed1997

Body temperatures and oxygen consumption during skin-to-skin (kangaroo) care in stable preterm infants weighing less than 1500 grams.

BACKGROUND: More and progressively smaller preterm infants are taken out of the incubator and placed skin to skin on their mother's chest to promote bonding, despite concerns that the infants are exposed to cold during this intervention. OBJECTIVE: To test the hypothesis that skin-to-skin care is a cold stress for preterm infants weighing less than 1500 gm, with a decrease in rectal temperature, a decrease in peripheral skin temperature, or an increase in oxygen consumption compared with conditions monitored during incubator care. STUDY DESIGN: We studied 22 stable, spontaneously breathing preterm infants weighing less than 1500 gm (appropriate in size for gestational age), who had their first skin-to-skin care in the first week of life. We continuously measured rectal temperature, peripheral skin temperature (foot), and oxygen consumption (indirect calorimetry) for 1 hour in a thermoneutral incubator, during 1 hour of skin-to-skin care, and for another hour in the incubator. Mean values for the three periods were compared by analysis of variance. RESULTS: During skin-to-skin care the mean rectal temperature was 0.2 degree C (p < 0.01) and the peripheral skin temperature was 0.6 degree C (p < 0.01) higher than during the preceding hour in the incubator. Back in the incubator, body temperatures returned to values recorded before skin-to-skin care. Oxygen consumption during skin-to-skin care (6.1 +/- 0.9 ml/kg per minute) was not significantly higher than in the incubator (5.8 +/- 0.8 ml/kg per minute). CONCLUSION: For stable preterm infants weighing less than 1500 gm and less than 1 week of age, 1 hour of skin-to-skin care is not a cold stress compared with care in a thermoneutral incubator.

Body Temperature↗
PubMed1997

Comparison of face mask, head hood, and canopy for breath sampling in flow-through indirect calorimetry to measure oxygen consumption and carbon dioxide production of preterm infants < 1500 grams.

Complete sampling of expired air is essential for accurate O2 consumption(CO2 production) [VO2(VCO2)] measurements with flow-through indirect calorimetry. In preterm infants complete sampling is critical, because only low sampling flows can be used. The accuracy of the various breath sampling systems at low flows and their patient compatibility is untested. We therefore measured 1) the accuracy of VO2(VCO2) measurements with a face mask, a head hood, and a canopy in vitro at low sampling flows; 2) the effect of breathing on measurements with the face mask; and 3) the effect of breath sampling systems on activity and body temperature of preterm infants. VO2(VCO2) were measured with a Deltatrac II. In vitro we used a methanol miniburner incorporated into a doll, which could simulate low VO2(VCO2) and tidal breathing. In vivo we studied seven preterm infants < 1500 g. With the face mask VO2(VCO2) measurements were accurate at a flow of 3 L/min (error -1 +/- 0.8%), when tidal volume was < 15 mL/breath and the distance between mask and manikin < 1 cm. With hood and canopy VO2(VCO2) were underestimated at a flow of 3 L/min (error -13 +/- 1% and -14 +/- 5%), and results were markedly influenced by body position. For accurate measurements, the hood needed a flow of 4.5 L/min, the canopy 8.3 L/min. In vivo the face mask did not increase heart rate, respiration, activity, or rectal temperature, but hood and canopy increased rectal temperature by 0.3-0.4 degree C. For VO2(VCO2) measurements in infants < 1500 g, a face mask should be used, which is accurate at low flows and does not change body temperature. Accuracy at low flows and patient compatibility of breath sampling systems should be evaluated and reported for VO2(VCO2) measurements in preterm infants.

Body Temperature↗
PubMed1997

Thyrotropin-releasing hormone gene expression by anterior pituitary cells in long-term cultures is influenced by the culture conditions and cell-to-cell interactions.

It has been suggested that TRH, synthesized by anterior pituitary (AP) cells in long-term monolayer cultures, may act as a paracrine or autocrine regulator. Because local control through messenger molecules depends on the cellular microenvironment, we were interested in studying the synthesis of TRH by AP cells in different culture systems and under various conditions. When AP cells were cultured as monolayers in medium containing 10% FCS for long periods of time (up to 3 weeks), a considerable increase in TRH content and prepro-TRHmessengerRNA (preproTRHmRNA) levels could be demonstrated by RIA and Northern blot analysis, whereas the cellular content of the TRH-like peptide pyroGlu-Glu-Pro-NH2 decreased with time in culture to undetectable levels. The release of TRH could be stimulated by depolarizing concentrations of K+ (55 mM), by the Ca++ ionophore A23187, and by GnRH, but not by CRH or GRF, indicating that TRH is stored in gonadotropes. Moreover, a combined in situ hybridization and immunocytochemical analysis demonstrated colocalization of LH in preproTRHmRNA-positive AP cells. When AP cells were cultured as reaggregates in the same (FCS-containing) medium, only a marginal increase in TRH content and preproTRHmRNA levels was observed. Irrespective of the culture systems and the culture conditions used, TRH gene expression was not observed when FCS was omitted. These results indicate that TRH gene expression more likely reflects derepression, rather than induction, of the TRH gene.

Animals↗
PubMed1997

3,5-diiodo-L-thyronine stimulates type 1 5'deiodinase activity in rat anterior pituitaries in vivo and in reaggregate cultures and GH3 cells in vitro.

Local deiodination of L-thyroxine (T4) to the active thyroid hormone T3 via two 5'deiodinase isoenzymes (5'DI and 5'DII) plays an important role for various T3-dependent functions of the anterior pituitary (AP). Recently, it was reported that 3,5-T2, the 5'deiodination product of T3, acts as a specific agonist in the feedback mechanism on TSH secretion at the pituitary level. We now examined the effects of 3,5-T2 on pituitary 5'deiodinase activities in vivo in male, adult rats and in vitro using rat AP reaggregate cultures and the somatomammotroph cell line GH3. 5'DI activity in the AP was transiently increased after a single injection of 3,5-T2. Serum TSH levels declined, and 24 h after 3,5-T2 application, betaTSH steady-state mRNA levels in the APs were markedly lower. In reaggregate cultures of the AP, 3,5-T2 stimulated 5'DI activity 24 h after application, dose-dependently. Compared with 5'DI activities, those of 5'DII were an order of magnitude lower, in vivo as well as in vitro, and were rapidly and transiently decreased by the higher dose of 3,5-T2. GH3 cells responded to 3,5-T2 and T3 by an 1.7-fold stimulation of 5'DI activity. Stimulation of DNA-binding was demonstrated in electrophoretic mobility shift assays for a specific RXR-containing protein complex with a DR+4 thyroid hormone response element of the human type 1 5'DI promoter using nuclear extracts from GH3 cells treated with 3,5-T2. In summary, 3,5-T2 and T3 exert direct thyromimetic effects on 5'DI activity and TSHbeta expression at the pituitary level. 5'DI is regulated by its substrate(s) and/or products and may serve an important function within the modulation of thyroid hormone-dependent gene expression in the AP.

Analysis of Variance↗
PubMed1997

Regulation of the adenohypophyseal thyrotropin-releasing hormone-degrading ectoenzyme by estradiol.

TRH is inactivated by the TRH-degrading ectoenzyme, a TRH-specific metallopeptidase. At the pituitary level, this enzyme is stringently regulated by thyroid hormones. We describe here gender-related differences and the effect of estradiol (E2) on the expression of this enzyme in the anterior pituitary. Compared with male rats, only about one third of the enzymatic activities and the messenger RNA levels were found in the anterior pituitary of female rats, whereas the TRH receptor transcript levels were found inversely related. When male rats received a single injection of 0.5 microg E2/100 g BW, the enzymatic activity decreased to 65% of control values within 14 h, preceded by a decrease of the transcript levels to 25% of control within 6 h. Basal values were reached again 24-48 h after the injection. E2 had no effect on the expression of the enzyme in the brain. In vivo and with GH3 cells in vitro, E2 effectively counteracted the increase in enzymatic activity induced by T3, whereas neither testosterone nor progesterone, aldosterone, or dexamethasone showed any significant effects. Because the expression of the adenohypophyseal TRH-degrading ectoenzyme is tightly regulated by both T3 and E2 with adequate dynamics, we conclude that this peptidase serves integrative functions for the control of TRH-stimulated hormone secretion.

Aminopeptidases↗
PubMed1997

Significant elevation of tumour-associated isoforms of soluble CD44 in serum of normal individuals caused by cigarette smoking.

While performing a prospective study on sCD44 variant isoforms as tumour markers in certain malignancies, we detected relevant differences in the control group between non-smokers and smokers. For a detailed evaluation of these findings, serum levels of sCD44 variant proteins, including sequences encoded by exon v5 and exon v6, respectively, were adjusted to sex, age and smoking habit. We were able to demonstrate a significant elevation of serum levels of sCD44v5 and sCD44v6 in normal individuals due to cigarette smoking (non-smokers to smokers: sCD44v5: 33 +/- 11 microg/l to 62 +/- 30 microg/l; sCD44v6: 142 +/- 34 microg/l to 232 +/- 86 microg/l). Stepwise multiple linear regression analysis of the concentrations of sCD44v5 and sCD44v6 on the possible influence factors sex, age and smoking habit revealed cigarette smoking as the only factor influencing these isoforms (both p << 0.001). Further investigations have to elucidate a possible clinical importance of these findings in smokers. However, in patients with suspected or proven malignancy the diagnostic specifity of sCD44v5 and sCD44v6 is diminished due to this observation.

Antigens, Neoplasm↗
PubMed1997

Urinary excretion of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in rats.

TRH-like immunoreactivity (TRH-LI) was estimated in methanolic extracts of rat tissues and blood by RIA using antiserum 4319, which binds most peptides with the structure pGlu-X-ProNH2, or antiserum 8880, which is specific for TRH (pGlu-His-ProNH2). TRH-LI (determined with antiserum 4319) and TRH (determined with antiserum 8880) contents were 8 and 8 ng/g in brain, 216 and 222 ng/g in hypothalamus, 6.5 and 6 ng/g in pancreas, 163 and 116 ng/g in male pituitary, 105 and 77 ng/g in female pituitary, 1 and 0.1 ng/g in salivary gland, 61 and 42 ng/g in thyroid, 12 and 3 ng/g in adrenal, 3 and 0.3 ng/g in prostate, and 11 and 0.8 ng/g in ovary respectively. Blood TRH-LI (antiserum 4319) and TRH (antiserum 8880) levels were 31 and 18 pg/ml in male rats, and 23 and 10 pg/ml in female rats respectively. Unextracted serum obtained from blood kept for at least 1 h at room temperature no longer contained authentic TRH but still contained TRH-LI (males 20.3 +/- 3.1, females 15.9 +/- 3.0 pg/ml; means +/- S.E.M.). Isocratic reverse-phase HPLC showed that TRH-LI in serum is largely pGlu-Glu-ProNH2 (< EEP-NH2), a peptide previously found in prostate and anterior pituitary. In urine, TRH-LI (antiserum 4319) and TRH (antiserum 8880) levels were 3.21 +/- 0.35 and 0.32 +/- 0.04 ng/ml in male rats and 3.75 +/- 0.22 and 0.37 +/- 0.04 ng/ml in female rats respectively (means +/- S.E.M.). Anion-exchange chromatography on QAE-Sephadex showed that urine of normally fed rats contains both basic/neutral TRH-LI (b/n TRH-LI) and acidic TRH-LI (aTRH-LI) in a ratio of approximately 40:60, and further analysis by HPLC indicated that aTRH-LI represents < EEP-NH2. Analysis of food extracts and urine from fasted rats demonstrated that b/n TRH-LI is derived from food particles spilled by the rats during urine collection, while aTRH-LI is endogenously produced. While urinary aTRH-LI levels were higher in female than in male rats (2.99 +/- 0.41 vs 2.04 +/- 0.20 ng/ml), the daily urinary excretion was similar in both sexes (females 15.6 +/- 1.4, males 19.5 +/- 2.0 ng/day). Intravenously injected < EEP-NH2 disappeared from serum with a half-life of approximately 1 h, and was recovered unchanged and quantitatively in urine. In contrast, when < EEP-NH2 was administered with food, only approximately 0.5% was recovered in urine. The urinary clearance rate of serum TRH-LI amounted to 0.52 +/- 0.10 ml/min in males and 0.34 +/- 0.05 ml/min in females. In view of the presence of < EEP-NH2 in the anterior pituitary gland, and the regulation of its content in parallel with gonadotrophins, we examined the possibility that serum < EEP-NH2 is of pituitary origin and correlates with gonadotrophin secretion. However, treatments that alter pituitary < EEP-NH2 content and gonadotrophin release had no effect on serum TRH-LI or urinary aTRH-LI. In conclusion, the TRH-like peptide < EEP-NH2 is present in rat serum and is excreted into the urine. Moreover, < EEP-NH2 in serum and urine is not derived from rat food and is probably not of pituitary origin.

Adrenal Glands↗
PubMed1997

Specific detection of his-tagged proteins with recombinant anti-His tag scFv-phosphatase or scFv-phage fusions.

Using a cell-bound immunogen, we have generated a monoclonal antibody, 3D5, that recognizes carboxy-terminal oligo-histidine tags (His tags) on a wide variety of proteins. From this monoclonal antibody, we have generated a single-chain fragment of the variable domains (scFv), a dimeric scFv-alkaline phosphatase fusion and an oligovalent scFv-display phage. The antibody in its various formats is an effective tool used in fluorescence-activated cell sorting analysis, the BIAcore method, Western blots and enzyme-linked immunosorbent assay (ELISA). Western blots and ELISAs can be developed directly by using crude extracts of E.coli cells that produce the scFv-alkaline phosphatase fusion, thus providing an inexhaustable and convenient supply of detection reagent. Alternatively, oligovalent scFv-displaying phage can be used directly from culture supernatants for this purpose. The dissociation constants, KD of the peptide KGGHHHHH (KD = 4 x 10(-7) M) and of imidazole (KD = 4 x 10(-4) M) were determined. Molecular modeling of the Fv fragment suggests the occurrence of two salt bridges between the protonated histidine side chains of the peptide and the acidic groups in the antibody, explaining why the antibody or the substrate may be eluted under mildly basic conditions.

Antibodies, Monoclonal↗
PubMed1997

Increased serum levels of soluble CD44-isoform v5 in rheumatic diseases are restricted to seropositive rheumatoid arthritis.

Serum levels of sCD44v5 were measured in 134 patients with definite inflammatory rheumatic diseases (IRD) using a sandwich type ELISA. 94 patients suffered from erosive IgM-rheumatoid factor positive rheumatoid arthritis (RA+), 20 with undifferentiated seronegative polyarthritis, 12 with osteoarthropathia psoriatica and psoriasis vulgaris, 3 with systemic lupus erythematosus, 3 with scleroderma and 2 with reactive arthritis. Elevated serum levels (> 58 ng/ml to 221 ng/ml; median: 93 ng/ml) were only detected in 54/94 (57%) patients with RA+, but not in other IRD. They correlated with advanced stages of disease (Steinbrocker stages III + IV; p < 0.05), elevated CRP-levels (p < 0.01) and higher measurements of IgM rheumatoid factor.

Adult↗
PubMed1997

A natural language parsing system for encoding admitting diagnoses.

Free-text or natural language documents make up an increasing part of the computerized medical record. While they do provide accessible clinical information to health care personnel, they fail to support processes that require clinical data coded according to a shared lexicon and data structure. We have developed a natural language parser that converts free-text admitting diagnoses into a coded form. This application has proven acceptably accurate in the experimental laboratory to warrant a test in the target clinical environment. Here we describe an approach to moving this research application into a production environment where it can contribute to the efforts of the Health Information Services Department. This transition is essential if the products of natural language understanding research are to contribute to patient care in a routine and sustainable way.

Diagnosis-Related Groups↗
PubMed1997

Evaluation of soluble CD44 splice variant v5 in the diagnosis and follow-up in breast cancer patients.

Aberrant expression of CD44 splice variants has been detected on a variety of human tumor cells. Overexpression of specific isoforms has been shown to be associated with metastasis and poor prognosis in breast cancer. We evaluated the possible utility of soluble CD44 splice variant v5 (sCD44v5) as a circulating, tumor-associated marker in breast cancer patients. Serum levels of sCD44v5 were determined in 147 healthy volunteers, in 53 patients with nonmalignant breast disease, in 85 patients with breast cancer at presentation, in 13 patients with recurrence and in 73 patients with active metastatic disease. Statistically, the levels at presentation in stages I-IV, in benign disease, and in a female control group were not significantly different. First longitudinal studies over 1-2 years in the follow-up of 28 patients who have remained tumor-free showed considerable between-patient variation while the intrapatient levels remained within relatively narrow limits. In patients with active metastatic disease, elevated levels of sCD44v5 (> 58 ng.ml-1) were detected in 50% of the cases with marked elevation in only 26%. In these cases, sCD44v5 correlated with the extent of metastatic disease and fell during clinical response to cytoreductive therapy. In comparison with CA15-3 in the patients' follow-up serum levels of sCD44v5 proved to be much less sensitive concerning lead time, percentage of raised serum levels at the time of recurrence and in metastatic disease. The value of sCD44v5 determinations in breast cancer patients was further limited by the poor diagnostic specificity of this marker due to elevated levels in smokers and chronic inflammatory disease.

Alternative Splicing↗
PubMed1996

Accumulation of ochratoxin A in rat kidney in vivo and in cultivated renal epithelial cells in vitro.

In this study we determined the distribution of ochratoxin A (OTA) in renal tissue as well as its content and binding pattern in different cell types stemming from the proximal tubule (OK cells) and collecting duct (MDCK cells) of the kidney. To obtain the net amount of OTA in renal tissue, the relative amount in the vascular compartment was calculated and subtracted. After acute administration of OTA to male Wistar rats, the highest concentrations were detected in the papilla and inner medulla. Concentrations in the outer medulla and in the cortical tissue were 50% lower. Sub-chronic (6 day) exposure to OTA resulted in a similar distribution in young rats (6 weeks old) but in a different distribution in adult rats (2 year old). Cultured MDCK-C11 cells (representing intercalated cells) showed a higher OTA content after 48 h of exposure to 1 mumol/1 OTA than another MDCK cell subtype (MDCK-C7, representing principal cells) and OK cells. Additionally, the capability of cell extracts to bind OTA was the highest in MDCK-C11 cells followed by cell extracts of OK cells and cell extracts of MDCK-C7 cells. In two cell types studied, OK and MDCK-C11 cells, OTA was bound preferentially by organellar components and less by cytosolic ones.

Albumins↗
PubMed1996

Paternal and maternal DNA lineages reveal a bottleneck in the founding of the Finnish population.

An analysis of Y-chromosomal haplotypes in several European populations reveals an almost monomorphic pattern in the Finns, whereas Y-chromosomal diversity is significantly higher in other populations. Furthermore, analyses of nucleotide positions in the mitochondrial control region that evolve slowly show a decrease in genetic diversity in Finns. Thus, relatively few men and women have contributed the genetic lineages that today survive in the Finnish population. This is likely to have caused the so-called "Finnish disease heritage"-i.e., the occurrence of several genetic diseases in the Finnish population that are rare elsewhere. A preliminary analysis of the mitochondrial mutations that have accumulated subsequent to the bottleneck suggests that it occurred about 4000 years ago, presumably when populations using agriculture and animal husbandry arrived in Finland.

Agriculture↗
PubMed1996

Carnosine-synthesis in cultures of rat glial cells is restricted to oligodendrocytes and carnosine uptake to astrocytes.

Cultures of glial cells consisting predominantly of oligodendrocytes and astrocytes were prepared to study whether the biosynthesis of carnosine (beta-Ala-His) and the cellular uptake of this dipeptide are processes which are associated with a specific cell type. Uptake of the radiolabeled precursor beta-alanine was observed in both cultures. Synthesis of radiolabeled carnosine, however, was only observed in oligodendrocyte cultures prepared from rat brain and spinal cord. During oligodendrocyte cultivation we observed a significant increase in the rate of carnosine synthesis which correlates with the differentiation of these cells as revealed by immunostaining with antibodies against oligodendrocyte markers. Carnosine synthesis was not observed in astroglia cell cultures that were depleted of residual O2-A progenitor cells and oligodendrocytes by antibody mediated complement cell killing. Contrary to the synthesis, carnosine was found to be taken up effectively only by astrocytes but not by oligodendrocytes.

Animals↗
PubMed1996

Dipeptide uptake: a novel marker for testicular and ovarian macrophages.

BACKGROUND: Testicular and ovarian macrophages seem to be involved in paracrine regulation of steroidogenesis. Markers suitable for the identification of these cells under viable conditions would allow new experimental approaches in the study of biological interactions between hormone-producing cells and tissue macrophages. METHODS AND RESULTS: Dipeptide uptake was studied in primary cultures from rat testis and ovaries with the fluorescent dipeptide derivative beta-Ala-Lys-N epsilon-aminomethylcoumarin acetic acid (AMCA). Fluorescence microscopic studies revealed that the reporter peptide accumulated specifically in testicular macrophages, which were identified by subsequent immunostaining with the OX-42 antibody. In the ovarian cultures, however, transport of the fluorescence-labeled dipeptide was observed in cells that exhibited the morphological characteristics of macrophages but did not show positive immunoreactivity against the antibody employed. In both cases, dipeptide accumulation was blocked by the addition of Tyr-Gly, thus indicating that transport was not due to endocytosis. Competition studies performed with primary cultures from testis have shown that di-and tripeptides effectively reduce uptake of the tracer peptide, whereas compounds without an alpha- or beta-amino group, such as captopril and benzylpenicillin, do not. CONCLUSIONS: These results indicate that the testicular and ovarian macrophages are equipped with a dipeptide transport system. The selective accumulation of the fluorescent dipeptide derivative beta-Ala-Lys-N epsilon-AMCA in testicular and ovarian macrophages permits the identification of these cell types under viable conditions.

Amino Acids↗
PubMed1996

Development of a rapid means of estimating the haemoglobin F content of candidate fetal cells isolated from maternal blood using HPLC.

Prenatal diagnosis of genetic disorders in nucleated fetal red blood cells present in maternal blood requires methods to detect and enrich for such cells. Here we describe a rapid high performance liquid chromatography (HPLC) method that allows one to determine as few as 100 cells containing haemoglobin F (HbF) in the presence of a vast excess of haemoglobin A (HbA)-producing cells. The HPLC separations of haemoglobins were performed with a weak cation exchange column-silica gel-bound asparaginic acid-and ammonium phosphate buffer as the mobile phase. Separations were carried out in 7 min. When applied to estimation of the recovery of fetal cells from maternal blood, the HPLC method indicates in a timely manner whether or not to proceed with further techniques (i.e., FISH or PCR). Several current techniques such as Ficoll gradients and fluorescence (FACS) or magnetic (MACS) activated cell sorting were thus evaluated. Unexpectedly, our method indicates high cell losses with both single gradient and triple density Ficoll pre-enrichment methods. Less than 20 per cent of the nucleated red blood cells can be recovered in the most optimal setting. Lysis of erythrocytes may be an alternative technique that leaves nucleated red blood cells of all maturation stages intact. Thus, any further improvements in the technology for fetal cell recovery may be aided by monitoring the yield with HPLC.

Cell Separation↗
PubMed1996

Projuvenoids: synthesis and biological evaluation of sulfenylated, sulfinylated, and sulfonylated carbamates.

Applying the proinsecticide principle developed earlier for neurotoxic carbamate insecticides, a series of new N-sulfenylated, N-sulfinylated, and N-sulfonylated derivatives of fenoxycarb were synthesized and evaluated for juvenile hormone mimicking activity. Laboratory evaluations of the compounds using Pieris brassicae and Sitophilus oryzae, as well as field experiments using Bemisia tabaci, showed that several symmetrical biscarbamates with either a sulfenyl or sulfinyl bridge possessed higher activity than the parent carbamate. From the unsymmetrical compounds containing biologically inert derivatizing moieties, one of the sulfenylated biscarbamates also showed improved activity against P. brassicae. The changes in the biological activity of the sulfur-containing derivatives compared to that of the parent compound are attributed to the modified physicochemical characteristics, i.e., increased lipophilicity facilitating penetration, transport, as well as protection of the compound from metabolism.

Animals↗