PubMed Health⌕ Search

Biomedical subjects

C Otto

Publications and source records attributed to C Otto.

At least 19 recordsLinked to original sources
PubMed1992

Polarization sensitive coherent anti-Stokes Raman scattering spectroscopy of the amide I band of proteins in solutions.

Polarization sensitive coherent anti-Stokes Raman scattering (PCARS) spectroscopy is a fruitful technique to study Raman vibrations of diluted molecules under off-electron resonant conditions. We apply PCARS as a direct spectroscopic method to investigate the broad amide I band of proteins in heavy water. In spontaneous Raman spectroscopy, this band is not well resolved. We fit a number of spectra taken of each protein under different polarization conditions, with a single set of parameters. It then appears that some substructure is observed in the amide I band. From this substructure, we determine the percentage of alpha-helix, beta-sheet, and random coil for the proteins lysozyme, albumin, ribonuclease A, and alpha-chymotrypsin.

Amides↗
PubMed1991

The hydrogen-bonding structure in parallel-stranded duplex DNA is reverse Watson-Crick.

Raman spectra of the parallel-stranded duplex formed from the deoxyoligonucleotides 5'-d-[(A)10TAATTTTAAATATTT]-3' (D1) and 5'-d[(T)10ATTAAAATTTATAAA]-3' (D2) in H2O and D2O have been acquired. The spectra of the parallel-stranded DNA are then compared to the spectra of the antiparallel double helix formed from the deoxyoligonucleotides D1 and 5'-d(AAATATTTAAAATTA-(T)10]-3' (D3). The Raman spectra of the antiparallel-stranded (aps) duplex are reminiscent of the spectra of poly[d(A)].poly[d(T)] and a B-form structure similar to that adopted by the homopolymer duplex is assigned to the antiparallel double helix. The spectra of the parallel-stranded (ps) and antiparallel-stranded duplexes differ significantly due to changes in helical organization, i.e., base pairing, base stacking, and backbone conformation. Large changes observed in the carbonyl stretching region (1600-1700 cm-1) implicate the involvement of the C(2) carbonyl of thymine in base pairing. The interaction of adenine with the C(2) carbonyl of thymine is consistent wtih formation of reverse Watson-Crick base pairing in parallel-stranded DNA. Phosphate-furanose vibrations similar to those observed for B-form DNA of heterogenous sequence and high A,T content are observed at 843 and 1092 cm-1 in the spectra of the parallel-stranded duplex. The 843-cm-1 band is due to the presence of a sizable population of furanose rings in the C2'-endo conformation. Significant changes observed in the regions from 1150 to 1250 cm-1 and from 1340 to 1400 cm-1 in the spectra of the parallel-stranded duplex are attributed to variations in backbone torsional and glycosidic angles and base stacking.

Base Composition↗
PubMed1991

Laser irradiation and Raman spectroscopy of single living cells and chromosomes: sample degradation occurs with 514.5 nm but not with 660 nm laser light.

In Raman spectroscopic measurements of single cells (human lymphocytes) and chromosomes, using a newly developed confocal Raman microspectrometer and a laser excitation wavelength of 514.5 nm, degradation of the biological objects was observed. In the experiments high power microscope objectives were used, focusing the laser beam into a spot approximately 0.5 micron in diameter. At the position of the laser focus a paling of the samples became visible even when the laser power on the sample was reduced to less than 1 mW. This was accompanied by a gradual decrease in the intensity of the Raman signal. With 5 mW of laser power the events became noticeable after a period of time in the order of minutes. It is shown that a number of potential mechanisms, such as excessive sample heating due to absorption of laser light, multiple photon absorption, and substrate heating are unlikely to play a role. In experiments with DNA solutions and histone protein solutions no evidence of photo damage was found using laser powers up to 25 mW. No degradation of cells and chromosomes occurs when laser light of 660 nm is used. The most plausible explanation therefore seems to be that the sample degradation is the result of photochemical reactions initiated by laser excitation at 514.5 nm of as yet unidentified sensitizer molecules or complexes present in chromosomes and cells but not in purified DNA and histone protein samples.

Animals↗
PubMed1991

[Blunt aortic injury/choosing appropriate time for surgery].

Based on our experience in a cohort of 39 patients and also on the results of post-mortem findings obtained from the department of forensic medicine in Hamburg, we prefer to perform emergency surgery only in cases of aortic aneurysms over 6 cm in diameter, in cases of hemorrhage, or in coarctation syndrome. Because of the high incidence of concomitant multiorgan injuries, surgery for aortic lesions with only radiologic symptoms is not performed until a period of 2-8 weeks has elapsed since the injury, according to the degree of stabilisation. With this strategy, the mortality in surgical management of aortic injuries in our department is about 15%.

Aortic Aneurysm↗
PubMed1991

Fetal growth and development.

The advent and advancement of ultrasound technology have proved to be invaluable tools in the assessment of the fetus while still in the intrauterine environment. Ultrasound has given and continues to give us fresh insights into many aspects of the developing human. The area of fetal growth and development is a difficult one. Our lack of knowledge of the basic controlling influences has inhibited investigations in this area, but ultrasound has at least allowed us to begin to scratch the surface of this complex subject. We can now obtain very useful clinical information that usually has excellent correlation with gestational age, fetal size, fetal structure, and fetal function. We are just now beginning to document the natural history of many fetal abnormalities. Undoubtedly, advances in our knowledge of genetics and molecular biology and continuing technologic advances in imaging techniques will provide fresh insights and allow us to continue to probe and unlock the mysteries of fetal growth and development.

Biometry↗
PubMed1991

[Interpretation of clinical and serologic findings--1 1/2 years after a long-term coccidioidomycosis].

A 46-year-old soldier of the German airforce stayed in Texas/USA for 6 months. Without clinical complaints the patient revealed nodular lung infiltration and a cavern on a routine-chest-X-ray examination after his return. Serological, cytological, and histological examinations excluded a sarcoidosis, tuberculosis of the lungs and a neoplasm. The finding of precipitating antibodies and a positive skin reaction against coccidioidin led to the diagnosis of a primary pulmonary, spontaneously healed coccidioidomycosis, which did not need any antimycotic therapy.

Coccidioides↗
PubMed1990

Studying single living cells and chromosomes by confocal Raman microspectroscopy.

Many indirect methods have been developed to study the constitution and conformation of macromolecules inside the living cell. Direct analysis by Raman spectroscopy is an ideal complement to techniques using directly labelled fluorescent probes or of indirect labelling with mono- and polyclonal antibodies. The high information content of Raman spectra can characterize biological macromolecules both in solution and in crystals. The positions, intensities and linewidths of the Raman lines (corresponding to vibrational energy levels) in spectra of DNA-protein complexes yield information about the composition, secondary structure and interactions of these molecules, including the chemical microenvironment of molecular subgroups. The main drawback of the method is the low Raman scattering cross-section of biological macromolecules, which until now has prohibited studies at the level of the single cell with the exception of (salmon) sperm heads, in which the DNA is condensed to an exceptionally high degree. Ultraviolet-resonance Raman spectroscopy has been used to obtain single cell spectra (and F. Sureau and P. Y. Turpin, personal communication), but in this method absorption of laser light may impair the integrity of the sample. We have avoided this problem in developing a novel, highly sensitive confocal Raman microspectrometer for nonresonant Raman spectroscopy. Our instrument makes it possible to study single cells and chromosomes with a high spatial resolution (approximately less than 1 micron 3).

Animals↗
PubMed1990

Phytoalexins as part of induced defence reactions in plants: their elicitation, function and metabolism.

Microbial infection of plants or elicitation of cell cultures initiates substantial metabolic changes directed at the induction of defence reactions. The antimicrobial phytoalexins deserve special attention because they represent one essential component of plant resistance. The great structural diversity of phytoalexins and possible cellular sites for their toxic activity are discussed. Pterocarpan phytoalexin biosynthesis in Cicer arietinum is an example of the induction of extended biosynthetic pathways, their modes of regulation and metabolic links with constitutive secondary product formation. Elicitation of plant tissues represents a technique to induce simultaneously the formation of phytoalexins and increased levels of constitutive or other secondary products that do not normally accumulate. The biological function of phytoalexins and the pathways of their degradation by pathogenic fungi are outlined. Detoxification of phytoalexins by fungi may have important consequences for the practical application of these defence compounds and for the genetic transformation of fungi and plants. Phytoalexins accumulate in plants or cell cultures only transiently, because they are readily degraded or polymerized by extracellular peroxidases.

Fungi↗
PubMed1990

Clinical approach to prenatal detection of human structural defects.

Tremendous advances in prenatal diagnosis have allowed clinicians to recognize a variety of structural defects in the developing fetus. Guidelines for fetal ultrasonography and an approach to fetal evaluation are outlined. The developmental morphologic approach is emphasized as a way of categorizing congenital anomalies whether they are detected during prenatal or postnatal life. The use of this approach for diagnosing and managing fetal malformation syndromes is illustrated.

Congenital Abnormalities↗
PubMed1989

HLA-DP antigens in patients with chronic autoimmune thrombocytopenia (AITP).

AITP, a disease with well-defined autoimmune character, has been previously studied for a possible HLA association. However, no such association with antigens of the A, B, C or DR loci was found. As this does not exclude a possible association with HLA-DP antigens, we have investigated 36 patients with AITP for DP w1, w2, w3, w4 and w5 by primed lymphocyte typing using locally derived as well as the original DP reagents as used in the 9th International Histocompatibility Workshop. Comparison of antigen frequencies with those of 254 healthy controls revealed an increased frequency of DPw5 in the patient group which, however, was not statistically significant. Other discrepancies were not observed.

Adolescent↗
PubMed1988

Resonance Raman spectroscopy of complexes of the helix destabilizing proteins GP32 and GP5 with poly(rA) and poly(dA).

The bacteriophage T4 helix destabilizing protein (hdp) gp32 and its complexes with poly(rA) and poly(dA) were studied with ultra-violet resonant Raman spectroscopy. The UV-resonant Raman (UV-RR) spectrum of the complex of gp5, the coat protein of bacteriophage M13, with poly(dA) was also measured and is compared with the spectrum of the gp 32/poly(dA) complex. The excitation wavelength was 245.1 nm. This is on the far UV-side of the first absorption bands of adenine and near a "window" in the protein absorption spectrum. The overlap of fluorescence due to chromophores present in the protein and resonance Raman scattering was prevented by this choice of wavelength. The spectra of the protein/polynucleotide complexes are compared with the native nucleotide spectra measured at varying temperatures. The hyperchromicity which is expected when a nucleotide changes from a stacked to an unstacked conformation was not observed for poly(rA), neither upon temperature increase nor on protein binding. In both cases poly(dA) revealed a clear hyperchromicity. This different behavior of poly(rA) and poly(dA) is probably a consequence of their different conformations. The contributions of the proteins to the spectra is weak except for two bands, at 1550 and 1610 cm-1 due to tryptophan (in case of gp32) and one band near 1610 cm-1 due to tyrosine and phenylalanine.

Chemical Phenomena↗
PubMed1988

Pulmonary clearance of 99mTc-DTPA: influence of background activity.

We examined the effect of intravascular and tissue accumulation of tracer when measuring pulmonary clearance of sodium pertechnetate-labeled diethylenetriamine pentaacetate (99mTc-DTPA). Pigs were intubated with endobronchial tubes, permitting deposition of an aerosol of 99mTc-DTPA only into the left lung. Scintillation detectors recorded radioactivity separately from one thigh and from the lung and chest wall on the left and right side. 99mTc-DTPA was given intravenously after 30 min, so that the chest counts from the left lung could be corrected for background activity in either the right lung or the thigh. The uncorrected clearance half time (t1/2) mean +/- SE from the left chest was 118.5 +/- 14.4 min. When corrected for background activity in the right chest, the t1/2 was 82.1 +/- 10.5 min, and when corrected for background activity in the thigh, the t1/2 was 80.9 +/- 10.6 min. There was no significant difference between t1/2 corrected by the measurements from the right chest or the thigh, and in four of five animals the corrected t1/2 by either method was significantly different from the uncorrected t1/2 (P less than 0.05). There was no correlation between the uncorrected t1/2 and the magnitude of the required correction. We conclude that correction for intravascular and tissue accumulation of tracer is an important refinement of the technique and can easily be accomplished by measuring accumulation of tracer in the thigh.

Aerosols↗
PubMed1987

A Raman scattering study of the helix-destabilizing gene-5 protein with adenine-containing nucleotides.

Raman spectra of gp5 and complexes of gp5 with poly(rA) and poly(dA) have been determined and analysed. From a fit of the amide I-band with model spectra it follows that the secondary structure of gp5 contains 52% beta-sheet, 28% undefined conformation and 19% alpha-helix. The band at 1032 cm-1 due to phenylalanine has an anomalous intensity both in the spectra of the complexes and the free protein. This possibly indicates a stacked structure present in the protein. Binding of gp5 to poly(rA) and poly(dA) influences the intensity of bands near 1338 and 1480 cm-1 which are considered to be marker-bands for the phosphate-sugar-base conformer. A change in conformation of the nucleotides is also reflected by vibrations originating in the phosphate- and sugar-residues of the backbone. In the spectrum of complexed poly(rA) the intensity of the conformation sensitive band at 813 cm-1, which is due to the phosphodiester group, is zero. It seems that gp5 forces poly(rA) and poly(dA) to a similar conformation. A marker band for stacking interaction in poly(rA) indicates that stacking interactions in the complex have increased.

Coliphages↗