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P Kolb

Publications and source records attributed to P Kolb.

18 recordsLinked to original sources
PubMed2000

Energy landscape of streptavidin-biotin complexes measured by atomic force microscopy.

The dissociation of ligand and receptor involves multiple transitions between intermediate states formed during the unbinding process. In this paper, we explored the energy landscape of the streptavidin-biotin interaction by using the atomic force microscope (AFM) to measure the unbinding dynamics of individual ligand-receptor complexes. The rupture force of the streptavidin-biotin bond increased more than 2-fold over a range of loading rates between 100 and 5000 pN/s. Moreover, the force measurements showed two regimes of loading in the streptavidin-biotin force spectrum, revealing the presence of two activation barriers in the unbinding process. Parallel experiments carried out with a streptavidin mutant (W120F) were used to investigate the molecular determinants of the activation barriers. From these experiments, we attributed the outer activation barrier in the energy landscape to the molecular interaction of the '3-4' loop of streptavidin that closes behind biotin.

Biotin↗
PubMed2000

Tetrachloro- and tetrabromoarsonium(V) cations: raman and 75As, 19F NMR spectroscopic characterization and X-ray crystal structures of [AsCl4][As(OTeF5)6] and [AsBr4][AsF(OTeF5)5] .

The salts [AsX4][As(OTeF5)6] and [AsBr4][AsF(OTeF5)5] (X = Cl, Br) have been prepared by oxidation of AsX3 with XOTeF5 in the presence of the OTeF5 acceptors As(OTeF5)5 and AsF(OTeF5)4. The mixed salts [AsCl4][Sb(OTeF5)6-nCl(n-2)] and [AsCl4][Sb(OTeF5)6-nCl(n)] (n > or = 2) have also been prepared. The AsBr4+ cation has been fully structurally characterized for the first time in SO2ClF solution by 75As NMR spectroscopy and in the solid state by a single-crystal X-ray diffraction study of [AsBr4][AsF(OTeFs)5]: P1, a = 9.778(4) A, b = 17.731(7) A, c = 18.870(8) A, alpha = 103.53(4)degrees, beta = 103.53(4) degrees, gamma = 105.10(4) degrees, V = 2915(2) A3, Z = 4, and R1 = 0.0368 at -183 degrees C. The crystal structure determination and solution 75As NMR study of the related [AsCl4][As(OTeF5)6] salt have also been carried out: [AsCl4][As(OTeF5)6], R3, a = 9.8741(14) A, c = 55.301(11) A, V= 4669(1) A3, Z = 6, and R1 = 0.0438 at -123 degrees C; and R3, a = 19.688(3) A, c = 55.264(11) A, V= 18552(5) A3, Z = 24, and R1 = 0.1341 at -183 degrees C. The crystal structure of the As(OTeF5)6- salt reveals weaker interactions between the anion and cation than in the previously known AsF6- salt. The AsF(OTeF5)5- anion is reported for the first time and is also weakly coordinating with respect to the AsBr4+ cation. Both cations are undistorted tetrahedra with bond lengths of 2.041(5)-2.056(3) A for AsCl4+ and 2.225(2)-2.236(2) A for AsBr4+. The Raman spectra are consistent with undistorted AsX4+ tetrahedra and have been assigned under Td point symmetry. The 35Cl/37Cl isotope shifts have been observed and assigned for AsCl4+, and the geometrical parameters and vibrational frequencies of all known and presently unknown PnX4+ (Pn = P, As, Sb, Bi; X = F, Cl, Br, I) cations have been calculated using density functional theory methods.

Journal Article↗
PubMed1993

[Endonasal microsurgical treatment of lacrimal duct stenoses. Indications, technique and results].

In a retrospective study we examined the indications, results and complications of endonasal microscopic dacryocystorhinostomy. Eighty-five operations were evaluated. Surgical success was proven in 83% for all indications using a combination of subjective judgement and objective findings. For the so-called classic indications--postsaccal stenosis, functional stenosis dacryolith and acute empyema--the operation was successful in 91% of cases. There were no permanent side effects.

Adolescent↗
PubMed1992

Treatment of diarrhoea in human immunodeficiency virus-infected patients with immunoglobulins from bovine colostrum.

Diarrhoea and weight loss are found in more than 50% of patients with the acquired immunodeficiency syndrome (AIDS). In some patients the symptoms can be very severe, leading to death even in the absence of opportunistic infections. In 30% of these patients, enteric pathogens cannot be identified, and approximately only half of the identifiable aetiologic agents of diarrhoea in patients infected with the human immunodeficiency virus (HIV) were treatable with antibiotics. Immunoglobulins from bovine colostrum (Lactobin, Biotest, Dreieich, FRG) contain high titers of antibodies against a wide range of bacterial, viral and protozoal pathogens as well as against various bacterial toxins. Lactobin (LIG) is quite resistant to 24-h incubation with gastric juice. In a multi-center pilot study 37 immunodeficiency patients with chronic diarrhoea [29 HIV-infected patients, 2 patients with common variable immunodeficiency (CVID), one unidentified immunodeficiency, five patients with graft versus host disease (GvHD) following bone marrow transplantation] were treated with oral LIG (10 g/day for 10 days). Good therapeutic effects were observed. Out of 31 treatment periods in 29 HIV-infected patients 21 gave good results leading to transient (10 days) or long-lasting (more than 4 weeks) normalisation of the stool frequency. The mean daily stool frequency decreased from 7.4 to 2.2 at the end of the treatment. Eight HIV-infected patients showed no response. The diarrhoea recurred in 12 patients within 4 weeks (32.4%), while 19 patients were free of diarrhoea for at least 4 weeks (51.3%). In 5 patients intestinal cryptosporidiosis disappeared following oral LIG treatment. LIG treatment was also beneficial in 4 out of 5 GvHD patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

[Long-term artificial respiration at home in restrictive ventilation disorders].

Combined chest wall and lung alterations may lead to severe restrictive respiratory disorder. In advanced cases with hypercapnia, hypoxemia and oxygen intolerance during spontaneous breathing, there are almost insuperable therapeutic difficulties. Three of such patients have been treated, after tracheostomy, at home for 60, 34 and 22 months respectively by intermittent IPPV ventilation. With an improved quality of life all these patients survived up to now. This result seems to be encouraging.

Activities of Daily Living↗
PubMed1978

[Pacemaker-Twiddler's Syndrome (author's transl)].

A case of Pacemaker-Twiddler's Syndrome is presented. Rotation of a permanent pacemaker can result in a capstan effect, and the lead is drawn out of the right ventricle. Fixing thouroughly the pacemaker and the lead should be an useful prophylactic measure.

Aged↗
PubMed1976

Vectorcardiographic findings in Friedreich's ataxia.

Cardiac manifestations in Friedreich's ataxia occur frequently. We have studied 17 cases of Friedreich's ataxia, of which 94% showed a disturbance of the repolarization in the scalar ECG, 29% showed evidence of left ventricular hypertrophy. These changes are not specific but typical of Friedreich's ataxia. Vectorcardiograms were taken with the Frank-system. The vectorcardiographic findings showed not only the same changes as seen in the sclar ECG, but furthermore an atypical configuration of the QRS-loop was evident, which was not recognized in the scalar ECG. According to our experience compared with the scalar ECT, the vectorcardiographic investigations can be considered a more useful method in the diagnosis of Friedreich's ataxia.

Adult↗