PubMed Health⌕ Search

Biomedical subjects

K Biedermann

Publications and source records attributed to K Biedermann.

At least 37 records · Page 2Linked to original sources
PubMed1994

Changes in sleep and sleep electroencephalogram during pregnancy.

The impairment of sleep quality is a common complaint during pregnancy. To investigate the changes in sleep in the course of pregnancy, the sleep electroencephalogram (EEG) was recorded and analyzed in nine healthy women on 2 consecutive nights during each trimester of pregnancy. Waking after sleep onset increased from the second (TR2) to the third (TR3) trimester, whereas rapid eye movement (REM) sleep decreased from the first trimester (TR1) to TR2. Spectral analysis of the EEG in nonrapid eye movement (NREM) sleep revealed a progressive reduction of power density in the course of pregnancy. In comparison to TR1, the values in TR2 were significantly lower in the 10.25-11.0-Hz and 14.25-17.0-Hz bands. In TR3, the significant reduction extended over the ranges of 1.25-12.0 Hz and 13.25-16.0 Hz. The largest decrease (30%) occurred in the 14.25-15.0-Hz band. In REM sleep, the spindle frequency range was not affected, and a minor reduction of power density in some frequency bins below 12 Hz was present only in TR3. The study documents major alterations of the sleep EEG that are not evident from the sleep scores and that may be associated with the characteristic hormonal changes occurring during pregnancy.

Adult↗
PubMed1994

Relevance of the miscarriage-new pregnancy interval.

There is a wide divergence of opinion concerning the interval a woman should wait after a miscarriage before attempting a new pregnancy ("pregnancy interval"). Many authors recommend waiting 3-4 months in order to reduce the risk of another miscarriage [3, 6, 17, 21]. This retrospective study investigated whether a longer pregnancy interval lowers the risk of repeat miscarriage (R-risk) and/or prematurity. The association between parity and R-risk was also analyzed. Results showed that there are no proven reasons to recommend a waiting period between a miscarriage and a subsequent pregnancy, because the R-risk was around 20% irrespective of interval duration. Prematurity too is not influenced by a waiting period after miscarriage. There was, however, an association between parity and R-risk and risk of prematurity: nulliparae were more likely to have a repeat miscarriage (p < 0.05) or a preterm delivery in the next pregnancy (p < 0.05) than women who had already given birth to a child.

Abortion, Spontaneous↗
PubMed1994

Quantitative anti-p24 determinations can predict the risk of vertical transmission. Swiss HIV and Pregnancy Collaborative Study Group.

Quantitative serum antibody to p24 was evaluated as a predictor of risk of vertical transmission of human immunodeficiency virus type 1 (HIV-1) infection. HIV-positive mothers, 13 with HIV-infected children and 24 with noninfected children were investigated during pregnancy and at the time of delivery. A statistically significant difference in anti-p24 titers was found between the mothers with infected and those with noninfected children independent of whether antibodies were measured during pregnancy or at the time of delivery. High anti-p24 levels correlated with a low risk of vertical transmission, whereas low anti-p24 titers were associated with an increased risk of vertical transmission. Although the number of CD4+ T-cells was lower and neopterin and beta-2 microglobulin values were higher in the group of mothers with infected children than in the noninfected group, no statistical significance was achieved due to the small sample size.

Biopterins↗
PubMed1993

Characterization of Serratia marcescens nuclease isoforms by plasma desorption mass spectrometry.

Isoforms of Serratia marcescens nuclease found in the natural nuclease produced by S. marcescens and in recombinant nuclease produced by Escherichia coli were structurally characterized by peptide mapping using plasma desorption mass spectrometry. The nuclease isoforms produced and secreted from S. marcescens B10M1, which are present in much greater amounts than in S. marcescens W225 nuclease produced by E. coli, were characterized completely and the information used to facilitate characterization of the recombinant nuclease isoforms. After purification of the nuclease the isoforms were separated on a DEAE-cellulose anion-exchange column and then digested with endoproteinase Lys-C. The peptides generated were isolated by reverse-phase HPLC and their molecular masses determined by plasma desorption mass spectrometry. Comparison of the peptides from the native nuclease, Sm2, and the two isoforms, Sm1 and Sm3, revealed that they differed only in the N-terminus, the latter being found to lack three amino acids in Sm1 and one amino acid in Sm3. No interior post-translational changes were found in either of the three isoforms. Using this information we were able to confirm that Sm1, the isoform lacking three amino acids, was also present in very small amounts in recombinant S. marcescens W225 nuclease produced and excreted by E. coli.

Amino Acid Sequence↗
PubMed1993

Separation of isoforms of Serratia marcescens nuclease by capillary electrophoresis.

Three S. marcescens nuclease isoforms differing mainly in charge (native nuclease with pI 6.8 and two minor isoforms with pI 7.3 and 7.4) were separated using several different modes of high-performance capillary electrophoresis. Separation of the isoforms by free solution capillary electrophoresis was unsatisfactory. Separation by micellar electrokinetic capillary chromatography was therefore investigated in detail and the method optimized with respect to pH and sodium dodecyl sulphate concentration; in addition, the effect of adding various substances to control dispersion and avoid analyte adsorption at the capillary wall was examined. Under optimal conditions there was almost complete baseline separation of the two isoforms with basic pI whereas there was only partial separation of the native form and the isoform with pI 7.4. With capillary isoelectric focusing there was complete baseline separation of the native nuclease and the other two isoforms.

Amino Acid Sequence↗
PubMed1993

Isolation and characterization of the outer membrane proteins of Serratia marcescens W225.

The study addressed the general problem of fractionating cell envelopes in order to isolate the outer membranes of gram-negative bacteria. Whereas the cells are normally transformed into spheroplasts prior to disintegration and membrane separation, Serratia marcescens was found to be resistant to spheroplast formation using the procedures available, which were originally developed for Escherichia coli. An efficient technique for spheroplasting S. marcescens was therefore developed; this comprised combining osmotic shock and lysozyme-EDTA treatment of sucrose-conditioned cells. Spheroplasting efficiency and the amount of outer membrane protein recovered were highly dependent on the spheroplasting technique used. Separation of the outer and inner membranes was performed by two methods, isopyenic centrifugation and selective detergent solubilization with Sarkosyl. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the analysis of specific inner membrane marker enzymes revealed that the protein obtained by detergent solubilization was much purer than that obtained by isopycnic centrifugation. The outer membrane isolated accounted for 60% of the envelope proteins and had a buoyant density of 1.2502 g/cm3. The protein profile of the outer membrane determined by SDS-PAGE resolved into 12 distinct protein bands, 3 of which represented major proteins.

Adenosine Triphosphatases↗
PubMed1993

[Early recognition of fetal abnormalities by transvaginal ultrasonography].

Three case reports illustrate situations where transvaginal sonography (TVS) can be important for detecting foetal malformation. In each of these cases a reliable diagnosis was not possible by abdominal ultrasound either because the part of the foetus to be examined lay too low in the pelvis or because it could not be imaged clearly enough due to lack of amniotic fluid. As we would recommend in such cases, diagnosis was then made by TVS. Since the area which can be imaged by TVS is limited mechanically by the anatomical situation, however, it should not be used as the primary method for prenatal screening, whereas in certain selected cases it can provide information not obtainable otherwise.

Abnormalities, Multiple↗
PubMed1993

Characterization of proteinase A glycoforms from recombinant Saccharomyces cerevisiae.

Proteinase A produced by Saccharomyces cerevisiae carrying the gene PEP4 (which encodes the prepro-proteinase A on multicopy plasmids) was isolated and characterized by means of SDS/PAGE, laser desorption m.s. (l.d.m.s.) and high-performance capillary electrophoresis. Although proteinase A is normally located in the yeast vacuole, overexpression resulted in it being secreted. SDS/PAGE revealed that the product isolated from the culture medium comprised an approx, 7:3 mixture of two different forms of proteinase A, the apparent molecular masses of which were 42 and 40 kDa respectively. The exact mass of each form, measured by l.d.m.s., was 40,755 and 38,132 Da respectively. Further analysis employing N-glycosidase F digestion and CNBr cleavage revealed that the larger molecule was native proteinase A bearing carbohydrate moieties at Asn68 and Asn269, whereas the smaller molecule was a proteinase A variant glycoform lacking the carbohydrate moiety at Asn269. Capillary electrophoresis of both the normal and underglycosylated proteinase A glycoforms revealed charge heterogeneities attributable to differences in the phosphorylation level of the carbohydrate moiety at Asn68.

Aspartic Acid Endopeptidases↗
PubMed1993

Characterization of natural and recombinant nuclease isoforms by electrospray mass spectrometry.

Isoforms of natural and recombinant nuclease have been characterized on the basis of their M(r) as determined by electrospray m.s.. The natural nuclease was isolated and purified from Serratia marcescens B10M1 and the recombinant nuclease from Escherichia coli MT102 carrying the plasmid p403-SD2. The primary structure of each of the isoforms isolated from the nuclease preparations was established by comparing their mass with the known amino acid sequence derived from the nucleotide sequence of the nuc gene. All the preparations were found to be contaminated with the same N-terminal split variants of native nuclease, although the natural nuclease contained much larger amounts of these isoforms than did the recombinant nuclease. The structure of some of the isoforms could be verified by N-terminal sequencing, and nearly all of them by isoelectric focusing.

Endodeoxyribonucleases↗
PubMed1991

Case report 693: Schneckenbecken dysplasia.

Three siblings with SBD from consangineous parents are reported. The prenatal diagnosis of a short-limbed form of dwarfism was made by ultrasonography and the final diagnosis in the index case by radiography, demonstrating a short-limbed, platyspondylic dwarf with a snail-like configuration of the ilium and vertebral bodies, flat on AP and round on lateral view. The histological examination showed a generalized, severe disturbance of cartilage formation with marked hypercellularity of proliferating and resting zones, reduction of intercellular matrix, and shortening of the irregular columns of proliferating cartilage. The ultramicroscopic findings were nonspecific. This is the first report of SBD after the original description, bringing the total to 14 cases in 5 families. The correct radiological diagnosis and the differential diagnosis, in particular thanatophoric dysplasia, are essential for genetic counselling and obstetrical guidance of families affected with this autosomal recessive dysplasia.

Dwarfism↗
PubMed1991

Quantitative binding studies of a monoclonal antibody to immobilized protein-A.

Binding constants and column capacities are important factors for evaluating an affinity chromatography system. Scatchard plots based on classical equilibrium binding have been used to demonstrate how association constants and column capacities can be computed from simple binding experiments and a commercial computer program. The analysis has been demonstrated on a monoclonal antibody type IgG-1 Kappa against Serratia marcescens nuclease and a commercial protein-A column, Prosep-A. Additional analyses were performed with the same antibody and other protein-A affinity systems and the different binding constants and column capacities obtained confirmed the value of the analysis for evaluating an affinity system.

Antibodies, Monoclonal↗
PubMed1990

Fermentation studies of the secretion of Serratia marcescens nuclease by Escherichia coli.

The secretion of a Serratia marcescens nuclease was followed by fermentation with Escherichia coli. A plasmid, p403-SD2, carrying a 1.3-kilobase-pair insert with a 0.4-kilobase-pair region upstream of the nuclease gene caused a growth-phase-regulated expression of nuclease in E. coli in the same way as that seen in S. marcescens. Deletion of the regulatory gene generating plasmid p403-Rsa1 resulted in a constitutive expression of the nuclease. Anaerobiosis stimulated the expression from p403-SD2 in stationary growth phase by a factor of 10 compared with expression stimulated by cultivation in aerobic conditions; no such effect was found for plasmid p403-Rsa1. Different nutritional factors caused the expression level and the amount of extracellular nuclease to vary more when nuclease was expressed from plasmid p403-SD2 than when it was expressed from plasmid p403-Rsa1. A correlation between the regulatory gene and the extracellular secretion of nuclease is proposed.

Bacteriological Techniques↗
PubMed1989

Purification and characterization of a Serratia marcescens nuclease produced by Escherichia coli.

The primary structure and physical chemical properties were determined of a nuclease expressed and secreted by Escherichia coli. The plasmid p403-SD2 carried a DNA sequence isolated from Serratia marcescens encoding the enzyme. During cultivation of the E. coli cells, 85% of the enzyme was released to the growth medium. The enzyme was purified and exhibited a single band with a molecular weight about 30,600 daltons on SDS-PAGE similar to nuclease isolated from S. marcescens. The amino acid composition and the amino acid sequence determined directly confirmed the primary structure of 245 amino acids predicted from the DNA sequence, and, in addition, the two disulfide bridges were assigned. Several physical chemical properties were examined. The ability of the enzyme to cross the outer membrane is proposed to depend upon the formation of the proper structures during the folding process.

Amino Acid Sequence↗
PubMed1988

[Pathologic Papanicolaou class IV smear without histologic correlation--what should be done?].

13 of 188 patients with a Papanicolaou smear Type IV of the cervix showed histologically only abnormal epithelium, CIN I or II, a result which does not explain the cytologic result. For several reasons a hysterectomy was performed in 5 cases. In only one of these patients a pathological finding, an endometrial carcinoma stage 0, was detected. In the other 8 cases a routine procedure under regular colposcopic and cytologic control had been performed. According to the results during a median follow-up over 52 months, such routine procedure is justified, if the patient wants children and if respectively a regular colposcopic/cytologic control or a control curettage after 3-6 months is undertaken.

Adult↗