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B Krebs

Publications and source records attributed to B Krebs.

At least 55 records · Page 3Linked to original sources
PubMed1994

Genetic variability of the emm-related gene of the large vir regulon of group A streptococci: potential intra- and intergenomic recombination events.

One of the most prevalent genetic lineages of group A streptococci (GAS) harbors a genomic locus termed the large vir regulon, which contains an emm gene encoding the antiphagocytic M protein, and structurally related fcrA and enn (emm-related) genes encoding immunoglobulin-binding proteins. In the present study more than 100 large vir regulons from 42 different GAS serotypes were analyzed by PCR and partial DNA sequencing. On comparing these data to published sequences, sites of mutational and putative recombinational events were identified and ordered with respect to their intra/intergenic or intra/intergenomic nature. The emm-related genes were found to display small intragenic deletions or insertions, were completely deleted from, or newly inserted into the genome, or were fused to adjacent genes. Intergenomic exchanges of complete emm-related genes, or segments thereof, between different vir regulons were detected. Most of these processes seem to involve short flanking direct repeats. Occasionally, the structural changes could be correlated with changes in the functions of the encoded proteins.

Amino Acid Sequence↗
PubMed1994

The oligosaccharides of the Fe(III)-Zn(II) purple acid phosphatase of the red kidney bean. Determination of the structure by a combination of matrix-assisted laser desorption/ionization mass spectrometry and selective enzymic degradation.

Purple acid phosphatase of the common bean Phaseolus vulgaris (KBPase), a dimeric 110-kDa glycoprotein related to the mammalian purple acid phosphatases with a two-metal cluster at the active site contains five oligosaccharide side chains/monomer. The N-linked glycan structures were characterized by selective enzymic degradation in combination with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The purified protein was cleaved by cyanogen bromide. One 30-kDa large methionine-free fragment required a further tryptic digest. The peptides were separated by HPLC and the glycosylated species were identified both by their heterogeneous mass spectra and by an immunoassay. None of the glycopeptides proved to have more than one glycosylation site. The composition of the carbohydrate moieties were calculated by comparing the mass spectra of the glycopeptides before and after enzymic deglycosylation. These results were complemented by data from a carbohydrate composition analysis. In four of the five peptides an alpha 1-3 fucose attached to the asparagine-linked N-acetylglucosamine prevented removal of the glycan by peptide N-glycosidase F; peptide N-glycosidase A removed all carbohydrates from the peptides. To reveal the sequence of the carbohydrate moiety including the linkage positions between the different saccharides, one of the glycopeptides was degraded by specific exoglycosidases. The enzymic degradations by these hydrolases were monitored by mass spectrometry of small aliquots taken at intervals during the reaction. The detailed structure of this one glycan in conjunction with the respective mass spectra and the composition analysis were used to infer the structure of the other four glycans. All glycans of the KBPase have a complex-type xylose-containing structure with four of the five having an additional fucose.

Acid Phosphatase↗
PubMed1994

[Isochromanylpencillins].

(R/S)-Isochroman-1-carboxylic acid (1) is resolved to its enantiomers and as well as these reacted with 6-aminopenicillanic acid to the title compounds 2. The activity of the new penicillin-derivatives against gram positive and gram negative bacteria is compared with that of benzyl penicillin.

Bacteria↗
PubMed1993

Circadian variations in the number of actively secreting sebaceous follicles and androgen circadian rhythms.

Sebum excretion has been shown to demonstrate a circadian rhythm using a gravimetric method (cigarette paper). With the newly introduced method of Sebutape, we confirmed this periodicity and showed that the elevation in sebum excretion is correlated with an increase in the number of secreting follicles. We found, furthermore, that the number of secreting follicles on the forehead showed a distinct and statistically significant circadian rhythmicity, in contrast to those of the chest, which remained almost constant. The quantification in plasma levels of cortisol, melatonin, delta-4-androstenedione, dehydroepiandrosterone sulphate, and free testosterone showed no correlation with sebum excretion at either site. These observations suggest that local factors are involved in control of sebum secretion.

Adult↗
PubMed1992

Crystallization and preliminary crystallographic data of purple acid phosphatase from red kidney bean.

Purple acid phosphatase from red kidney bean has been crystallized from ammonium sulfate solutions in the pH range from 3.5 to 5.5. The crystal form is tetragonal bipyramidal and the largest crystals grew up to 2.0 mm long. Systematic absences indicate one of the enantiomorphic space groups P4(1)2(1)2 (92) or P4(3)2(1)2 (96) with cell dimensions a = b = 104.1(1) A and c = 308.7(2) A. The asymmetric unit contains one dimer with Mr of 110,700, determined by ultraviolet-laser desorption mass spectrometry. The crystals, with a salt-free density of 1.12 g/cm3 and a water content of 67%, diffract to 3.5 A.

Acid Phosphatase↗
PubMed1991

Protein-chemical standardization of the erythrocyte glutathione reductase activation test (EGRAC test). Application to hypothyroidism.

The erythrocyte glutathione reductase activation coefficient (EGRAC) is an index of riboflavin deficiency or, more exactly, of FAD deficiency in man. In this report a sensitive version of the EGRAC test is introduced that is based on the molecular properties of glutathione reductase and its FAD-free apoenzyme. The hemoglobin concentration of the blood sample can be estimated simultaneously using the spectrophotometric absorption at 340 nm. - The method was tested for 33 thyroidectomized patients in comparison with a euthyroid control group. From the average EGRAC values (1.40 vs. 1.22) it was deduced that the average free FAD level was approximately 2 times lower for the patients' than for the control group. Discussed is the role of the EGRAC test in hormonal and nutritional disorders.

Adult↗
PubMed1990

[Pain and dysesthesias in the mastectomy scar].

With the object of investigating the occurrence of pain and dysaesthesiae in the scar following mastectomy, 120 were interviewed by a standard questionnaire in a prospective study. These women had commenced postoperative control or treatment in the Department of Oncology in the University Hospital of Aarhus consecutively during a one-year period. One hundred and ten of these women were interviewed again one year later. In 92% of the patients with scar pain and dysaesthesiae, these appeared within the first three months postoperatively. At the first interview, 42 patients (35%) had scar pain and 15 of these (13%) experienced constant scar pain. One year later, 25 patients (23%) still had scar pain and 13 patients (12%) had experienced persistent scar pain throughout the entire year. Two of the patients (8%) with scar pain had constant pain while, at the second interview, 14 patients (56%) reported that the scar pain lasted for seconds. Twenty-seven patients (23%) had dysaesthesiae at the first interview while 29 patients experienced these continually one year after operation. Both the intensity and the duration of the scar pain diminished with the elapse of time. This held also true where dysaesthesiae were concerned but was not so marked.

Adult↗
PubMed1990

Activation signals in human lymphocytes: interleukin 2 synthesis and expression of high affinity interleukin 2 receptors require differential signalling for the activation of protein kinase C.

The mitogenic activation of resting T lymphocytes involves two distinct cellular events, the synthesis of the ultimate mitogen interleukin 2 and the synthesis and expression of receptors for it. In order to get more detailed information on the mechanisms associated with these activating steps (the effects of different stimuli, leading to activation of protein kinase C were investigated in human lymphocytes). The anti-T-cell receptor (TCR) and anti-CD3 monoclonal antibodies (BMA 031 and BMA 030, respectively), as well as the combination of the phorbol ester, TPA, with a calcium ionophore-induced interleukin 2 synthesis and subsequent proliferation in human peripheral blood lymphocytes. Incubation of cells with synthetic diacylglycerols and calcium ionophores proved to be effective in expression of high affinity interleukin receptors, no detectable amounts of interleukin 2 were, however, synthetized. When diacylglycerols were, however, added repetitively, interleukin 2 was also produced. Both anti-TCR/CD3 antibodies and TPA or DiC8 caused activation and translocation of protein kinase C from the cytosol to the plasma membrane. Significant differences, however, were observed between the time kinetics of the translocation of the enzyme. In plasma membranes of TPA-stimulated cells activation of protein kinase C was detectable up to 4 hr. In contrast, the highest specific activity of protein kinase C was measured in the plasma membranes after 15 min of DiC8 addition to cells. Anti-CD3 monoclonal antibodies activated protein kinase C in a biphasic manner. Shortly after binding of BMA 030 to the T cell antigen receptor/CD3 complex the activity of protein kinase C was increased in the plasma membrane, then it declined to control levels followed by a second long-lasting activation of the enzyme up to 4 hr. These results suggest different signal requirements for different activation steps. While for synthesis and expression of interleukin 2 receptors a short term activation of protein kinase C is sufficient, long-term activation of the enzyme is necessary for interleukin 2 synthesis in human lymphocytes.

Biological Transport↗
PubMed1990

5-Methoxypsoralen as a specific stimulating agent of melatonin secretion in humans.

The endocrine effects of the linear furocoumarin, 5-methoxypsoralen (Bergapten), were investigated in 11 normal adults according to a cross-over design with 2 conditions: a 1-week trial with 5-methoxypsoralen (5MOP) administered daily (40 mg/orally) at 0900 h, and after a 1-week period of washout, a similar 1-week trial with daily administrations of 5MOP at 2100 h. The subjects were living under normal nychtohemeral conditions. The plasma levels of melatonin, cortisol, TSH, PRL, and GH were evaluated by hourly blood samples over 24-h periods on the preceding day and on the last day of each condition. Our main finding is that 5MOP specifically stimulates melatonin secretion in humans, with a pronounced effect when administered during the dark phase of the day (at 2100 h). The other endocrine rhythms were unaffected by 5MOP administration. Melatonin has been shown to interact with the regulation of the human circadian system; this specific stimulation may, therefore, be of great interest in disorders associated with abnormalities of circadian rhythms.

5-Methoxypsoralen↗
PubMed1990

[Hourly serum cortisol assay over 24hr by immunoenzymology in depression].

Enzymoimmunoassays have been developed as alternatives to radioimmunoassays because they obviate the need for labelled compounds yet offering comparable specificity. The authors used an enzymoimmunoassay to investigate hourly serum cortisol levels over 24 hours in 6 patients (aged over 40 years) with endogenous depression (4 unipolar depressions, under antidepressor treatment and 2 bipolar depressions, without medication) and in 2 controls, aged 20 and 47 years. In agreement with literature data, a clear circadian rhythm was observed in controls and in the depressed patients, and hypercorticism was noted in one depressed patient. A trend towards phase advance in depression was seen in both the treated and untreated patients.

Adult↗
PubMed1989

Extended X-ray absorption fine structure (EXAFS) investigations of model compounds for zinc enzymes.

A test of the ability of extended X-ray absorption fine structure (EXAFS) to determine structural information with specific reference to zinc sites in enzymes has been made. X-ray absorption spectra of 18 compounds of zinc have been measured and the nearest-neighbour scattering has been interpreted using a Fourier transform and an ab initio technique. Empirical Zn-N, Zn-O, Zn-S and Zn-Cl amplitude and phase functions have been extracted from Zn(C3H4N2)4(ClO4)2, ZnO, Zn(S2COC2H5)2 and [N(CH3)4]2[ZnCl4], respectively and tabulated as a function of the wavevector with respect to 9660.0 eV X-ray energy. These amplitude and phase functions were then tested with respect to the other 14 compounds. For a single species of atoms in the first coordination shell the interatomic distances can be established to +/- 0.5 pm (+/- 5 x 10(-3) A) whilst when mixed shells exist errors in distances are +/-4 pm (+/- 40 x 10(-3) A). Coordination numbers are given to +/- 16% for the single species case a and +/- 25% for the mixed coordination case. Using the theoretical amplitude and phase functions of McKale et al. [(1988) J. Am. Chem. Soc. 110, 3763-3768] the deduced distances are systematically too small by an average of 0.6 pm (6 x 10(-3) A). The errors in the coordination numbers are 18%.

Enzymes↗
PubMed1989

Activation signals in human lymphocytes. Incorporation of polyunsaturated fatty acids into plasma membrane phospholipids regulates IL-2 synthesis via sustained activation of protein kinase C.

Human PBL activated with anti-TCR/CD3 mAb express high affinity receptors for IL-2, synthesize IL-2, and subsequently proliferate. In contrast, lymphocytes activated by dioctanoylglycerol (DiC8) and ionomycin express high affinity receptors; however, no IL-2 synthesis is detectable. Anti-TCR/CD3 antibodies, as well as DiC8 cause translocation of protein kinase C (PKC) from the cytosol to the plasma membrane. In DiC8-stimulated cells translocation of PKC is detectable after 15 min, then it declines to control levels. In lymphocytes activated by antiTCR/CD3 mAb translocation of PKC is detectable after 15 min, then it declines to control levels, followed by a second, long lasting activation of the enzyme up to 4 h. Addition of polyunsaturated fatty acids to DiC8 + ionomycin-treated cells leads to IL-2 synthesis and proliferation. Incorporation of poly-unsaturated fatty acids into plasma membrane phospholipids results in long term activation of PKC. The results suggest that elevated incorporation of polyunsaturated fatty acids and thus continuous activation and translocation of PKC represents a necessary early signal for IL-2 synthesis and proliferation in human lymphocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

5-Methoxypsoralen increases evening sleepiness in humans: possible involvement of the melatonin secretion.

The acute and short-term effect of 5-methoxypsoralen (5-MOP) on daytime sleepiness was investigated in 12 healthy subjects according to a double-blind cross-over design. 5-MOP (40 mg/day) or placebo was orally administered (one week each) at 16.00 h. 5-MOP significantly increases daytime sleepiness 4 to 5 h after administration without affecting the subsequent sleep efficiency and duration. We found a positive correlation between sleepiness and melatonin levels. Our findings suggest that the melatonin secretion may play a role in the effect of 5-MOP on sleepiness in humans.

5-Methoxypsoralen↗
PubMed1989

Arthroscopy and synovial hemangioma or giant cell tumour of the knee.

A synovial hemangioma was localized in two knees and a xanthomatous giant cell tumour in one knee by arthroscopy. It is concluded, that synovial hemangiomas will be discovered earlier and more frequently by arthroscopy. Intraarticular hemangiomas may be operated at once, but in case of hemangiomas of intermediate type an angiography is recommended.

Adolescent↗
PubMed1989

Circadian rhythms in depression and recovery: evidence for blunted amplitude as the main chronobiological abnormality.

Circadian rhythms of body temperature, plasma cortisol, norepinephrine (NE), thyroid stimulating hormone (TSH), and melatonin were compared in 16 endogenously depressed, 15 recovered (after 3 weeks of anti-depressant treatment), and 16 normal subjects. The depressed patients showed clear circadian rhythm abnormalities, consisting mainly in amplitude reduction. This amplitude reduction was significantly correlated with the patients' Hamilton depression scores. Normal circadian profiles were restored after recovery when amplitude, in particular, was increased. Features of the circadian rhythms observed in remission may be associated with antidepressant drug effects, whereas those observed in depression resemble the circadian rhythms observed in normal subjects living under conditions of temporal isolation and those of blind subjects. Our findings suggest that depression may be related both to a weakening of the coupling processes between internal pacemakers and to an abnormal sensitivity to environmental information.

Adult↗
PubMed1989

pH-controlled continuous cultivation of mycoplasmas.

The continuous cultivation of mycoplasmas in a pH-controlled metabolistat was investigated with the fermentative strain Mycoplasma mobile 163K and the nonfermentative strain Mycoplasma arthritidis ISR1. The addition of medium and the removal of culture suspension were regulated by acid production from glucose by M. mobile 163K and by ammonium production from arginine by M. arthritidis ISR1, respectively. For both strains the optimal pH for continuous growth was 7.0. The steady state could be maintained for at least 21 days. With CFU of 8.4 X 10(9) ml-1 (M. mobile 163K) and 3.2 X 10(9) ml-1 (M. arthritidis ISR1), the cell concentrations were slightly higher than those obtained in batch cultures. The dependence on the adjusted pH values was measured for several parameters, such as flow rate, CFU, glucose fermentation or production of ammonia, and gliding velocity. Since the long lag phases of batch cultures can be avoided, pH-controlled continuous cultures provide an appropriate system for the production of mycoplasma cells.

Acetates↗