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Biomedical subjects

C Otto

Publications and source records attributed to C Otto.

At least 127 records · Page 7Linked to original sources
PubMed1996

The agreement between ventricular volumes and ejection fraction by transesophageal echocardiography or a combined radionuclear and thermodilution technique in patients after coronary artery surgery.

OBJECTIVES: To study the reproducibility of and agreement between perioperative transesophageal echocardiographic (TEE) and radionuclide (RN) assessment of ventricular volumes and ejection fraction (EF). DESIGN: A prospective, blinded comparison of two methods of measurement. SETTING: A surgical intensive care unit in a university hospital. PARTICIPANTS: Patients after coronary artery bypass surgery. INTERVENTIONS: Left ventricular volumes and ejection fraction were simultaneously measured by radionuclide ventriculography and transesophageal echocardiography. Two sets of measurements were made in rapid succession with a third set after an interval. RESULTS: Reproducibilities of EF and ventricular volumes by TEE and RN were similar. At each set of measurements, the bias for radionuclide EF and TEE Simpson's rule EF, 0.03 +/- 0.05, 0 +/- 0.06, -0.01 +/- 0.07, respectively, for radionuclide EF and TEE area length EF 0.01 +/- 0.05, -0.01 +/- 0.05, -0.03 +/- 0.08, respectively, were significantly less than for radionuclide EF and TEE FAC 0.07 +/- 0.05, 0.05 +/- 0.05, 0.03 +/- 0.09. Poor agreement was observed between RNTD-EDV, and both of the TEE EDV measurements. CONCLUSION: EF measured by TEE area length and Simpson's rule method are as reproducible as TEE FAC and are more accurate estimates of RN EF. Poor agreement between methods of measuring end-diastolic volume was observed.

Aged↗
PubMed1996

Dipeptide uptake by adenohypophysial folliculostellate cells.

Dipeptide uptake was studied in primary cultures from rat anterior pituitaries by use of radiolabeled carnosine and the fluorescent dipeptide derivative beta-Ala-Lys-N epsilon-AMCA (AMCA is 7-amino-4-methylcoumarin-3-acetic acid). Fluorescence microscopic studies revealed that the reporter peptide specifically accumulated in the S-100 positive folliculostellate cells that do not produce any known hormone. The dipeptide derivative was taken up in unmetabolized form by an energy-dependent saturable process with apparent kinetic constants as follows: Michaelis constant, 19 microM; maximum velocity, 5.5 nmol.mg protein-1.h-1. This high-affinity transporter was strongly affected by inhibitors of sodium/proton exchangers and thus appeared to be driven by a proton gradient. Competition studies revealed that the peptide transporter exhibits broad substrate specificity with a preference for hydrophobic dipeptides. In contrast to free amino acids and the pseudotetrapeptide amastatin, tripeptides were also accepted. Compounds without an alpha- and beta-amino group, such as captopril, thiorphan, and benzylpenicillin, did not affect uptake of the reporter peptide, although they were substrates of the well-characterized intestinal and renal dipeptide transporters.

Amino Acids↗
PubMed1996

Aging affects the conformation of cholesterol in the human eye lens.

The distribution of 3-beta-OH-cholesterol along the optical axis of 20 human eye lenses of different ages was measured using confocal Raman microspectroscopy in combination with the 3-beta-hydroxysteroid-specific probe filipin. This non-destructive technique allow a spatially very detailed study of the distribution of 3-beta-OH-cholesterol in individual lenses. It revealed age-related changes of the 3-beta-OH-cholesterol distribution along the optical axis. The 3-beta-OH-cholesterol was found to be distributed asymmetrically along the optical axis and this distribution was found to change with age. The relative 3-beta-OH-cholesterol content in the anterior part of the lens decreases significantly with increasing age compared with its equal posterior counterpart. Additionally all the lenses have a very low 3-beta-OH-cholesterol content in the central part of their nuclear region, the area where the primary lens fibres are located.

Adolescent↗
PubMed1995

[Nutrition and cancer. Nutrition-associated risk for the development of various malignancies].

A scientific assessment of dietary risks encounters great difficulties, since reliable prospective studies are hardly possible, and the various forms of retrospective studies are associated with considerable error probabilities. Nevertheless, on the basis of the similar results obtained with numerous investigations, it is possible to make statements about definite or potential risks. Thus, the correlation between high levels of dietary fat and meat and colorectal cancer, and that between high levels of fat and mammary carcinoma, have been adequately demonstrated. Alcohol is a proven risk factor for numerous carcinomas of the gastrointestinal tract, in particular for tumors of the oropharynx and larynx, the esophagus and liver. But it may also be a possible risk factor for breast cancer and other gynecological tumors. Conversely, with respect to protective factors it is accepted that what is generally recognized to be a healthy diet (fruit, vegetables, fiber) can apparently offer a certain degree of protection from malignant disease.

Alcohol Drinking↗
PubMed1995

New approach to assess the cholesterol distribution in the eye lens: confocal Raman microspectroscopy and filipin cytochemistry.

Confocal Raman microspectroscopy (CRM) is a non-invasive, non-destructive, and sensitive analytical tool for the study of some aspects of the molecular organization of cells and tissues with high spatial resolution. Filipin, a polyene antibiotic, specifically binds to cholesterol, and its molecular structure predicts it to be Raman-active. The aim of the present study was to assess the potentialities of a combined CRM-filipin approach to study the distribution of cholesterol in the human eye lens. Paraformaldehyde-fixed human lenses were sliced (0.7 mm), incubated with filipin, and analyzed by CRM. Filipin proved to give a specific Raman signal at 1586 cm-1, hardly interfering with signals from lens proteins. The CRM-filipin approach proved to be extremely sensitive, allowing detection of cholesterol in the femtogram range. It has an excellent spatial resolution (0.2-0.5 micron 3) when using point measurements. Due to the intrinsic anisotropy of membranes in the eye lens and therefore of the cholesterol distribution, a line-scan approach has to be adopted when fiber-to-fiber changes in cholesterol are of interest. The distribution of filipin along the optical axis of four human eye lenses was compared with data from the literature. The combined CRM-filipin approach is a highly specific and sensitive method for the study of cholesterol within cells and tissues. The spatial resolution is high and can be adapted to the desired discriminative power. The gross distribution of filipin along the optical axis obtained in this study is similar to that found in biochemical studies.

Cholesterol↗
PubMed1994

Raman microspectroscopic study of low-pH-induced changes in DNA structure of polytene chromosomes.

The effects of low-pH treatments on DNA structure in polytene chromosomes of Chironomus thummi thummi have been studied by Raman microspectroscopy. Measurements were carried out on chromosomes at low pH and on chromosomes reneutralized after a short exposure to low pH. Protonation of adenine residues and subsequent unpairing of adenine (A) and thymine (T) were found to commence already above pH 3.6 and are completed at pH 2.2. Protonation of the cytosine-guanine base pair also starts above pH 3.6. It leads to an intermediate protonated, most likely Hoogsteen-type, guanine-cytosine base pair. Unpairing of G and C residues starts between pH 2.6 and 2.2 and continues below pH 2.2. Brief treatment of chromosomes at a pH < or = 2.2, i.e., at a pH where both AT and GC base pairs are disrupted, was found to lead to irreversible changes in DNA conformation upon return to neutral pH. These were most pronounced after treatment with 45% acetic acid. More than 10% of the A and T residues was found to have adopted a non-B-DNA conformation. Evidence was found for denaturation of the B-form backbone. The amount of protein extracted from the chromosomes was strongly pH-dependent. Treatment at pH 3.6 did not cause noticeable protein extraction, while treatment with 45% acetic acid extracted more than 50% (by weight) of the chromosomal proteins.

Adenine↗
PubMed1994

Combined elastic and Raman light scattering of human eye lenses.

The distribution of the scattering coefficient (as defined in the appendix) at a wavelength of 647.1 nm along the visual axis of human eye lenses was investigated using a specially designed set-up for spatially resolved measurements of the intensity of the scattered light. For the same lenses, the distribution of the protein content was measured using confocal Raman microspectroscopy. Data collected by both methods were processed in terms of a recently developed theory of short-range, liquid-like order of crystallin proteins that accounts for eye lens transparency. Seven fresh intact human lenses of varying age have been investigated. In addition, elastic and Raman scattering measurements have been performed on fixed lenses. The main results and conclusions are: (1) Fixation significantly affects the light scattering properties of the eye lens. The average level of scattering increases and a change in the distribution of scattered light intensity along the visual axis occurs. Protein content and average distribution were not altered by fixation. (2) There are significant differences between the distribution of the scattering coefficient for lenses of different ages. For young lenses (18 and 20 years) regions with a low protein content (anterior and posterior cortex) show a higher level of elastic light scattering, while for older lenses (42-78 years old) there is no obvious correlation between the scattering level and protein content. (3) Changes in the level of light scattering along the visual axis of the lens cannot be explained by protein concentration effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Relation between local acoustic parameters and protein distribution in human and porcine eye lenses.

The purpose of this study is to characterize the eye lens (human, porcine) by acoustic measurements and to investigate whether relations exist with the local protein content. The acoustic measurements were performed with a 'scanning acoustic microscope' (SAM), operating at a frequency of 20 MHz. At this frequency the lateral resolution in the acoustic images was 150 microns. A double-transmission pulse-echo technique was employed to obtain acoustic parameter images of a central, 1-mm-thick slice of the lenses. The two-dimensional images were derived by ultrasonic spectroscopy displaying the ultrasound velocity, the attenuation at 20 MHz and the slope of the attenuation coefficient between 17 and 23 MHz. The images were summarized by profiles along the optical and equatorial axes of these parameters. Acoustic parameters were obtained from human lenses (n = 13) and porcine lenses (n = 10). The protein contents of human lenses were obtained from literature. Additionally, Raman microspectroscopy was used to measure the local protein content of porcine lenses (n = 3). Profiles along the optical and equatorial axes were obtained. The relation between the protein content and the acoustic parameters was obtained qualitatively by comparison of the shape of the profiles and, where possible, quantitatively by calculating the Pearson correlation coefficients. Furthermore, the results have been related to a statistical metastudy found in literature in which the relation between collagen, protein and acoustic velocity in various biological tissues was investigated. The results show a gradual decrease of the magnitude of the acoustic parameters from the centre to the periphery of the porcine eye lens, which is clearly equivalent to the decrease in profiles of the protein content. For the human lenses the acoustic characteristics and the protein content exhibit the same profile, fairly constant in the lens nucleus and decreasing towards the periphery of the lens cortex. Strong positive correlation coefficients for acoustic parameters and protein content for the porcine lens are found. It is concluded that protein concentration related phenomena can be investigated by measuring the acoustic parameters.

Adult↗
PubMed1993

Secondary structure of M13 coat protein in phospholipids studied by circular dichroism, Raman, and Fourier transform infrared spectroscopy.

There is considerable uncertainty about the precise secondary structure adopted by the M13 coat protein when embedded in a phospholipid bilayer. Circular dichroism (CD) spectroscopy suggests that a major change in the structure of the coat protein occurs upon membrane insertion. It is reported that the structure of the protein in the membrane has only about 50% alpha-helix, the rest being mainly in a beta-sheet conformation, whereas the protein is almost completely alpha-helical when intact in the phage. In this study we have undertaken a spectroscopic analysis using Fourier transform infrared, Raman, and CD spectroscopy to characterize the secondary structure of M13 coat protein when present in membranes consisting of dioleoylphosphatidylglycerol and dimyristoylphosphatidylglycerol. In sharp contrast to earlier CD studies, our results indicate that the coat protein in its membrane-embedded state has a very high alpha-helical content with virtually no beta-sheet structures present. This result indicates that the structures of the coat protein when intact in the phage or when embedded in the membrane are similar. Although our results differ from earlier CD studies, they are consistent with a recent NMR study, which showed that the M13 coat protein in sodium dodecyl sulfate micelles is primarily alpha-helical with no evidence for beta-sheet structure [Henry, G. D., & Sykes, B.D. (1992) Biochemistry 31, 5284-5297]. These results lead to the conclusion that the M13 coat protein can insert from the membrane-bound state into a virus particle with a similar secondary structure, without large energy implications.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage M13↗
PubMed1993

Influence of fiber, xylitol and fructose in enteral formulas on glucose and lipid metabolism in normal subjects.

To verify the benefit of nonglucose carbohydrates and fiber in enteral formula diets we studied the postprandial metabolism of eight healthy subjects after the intake of two helpings (25 g carbohydrates each) of five commonly used enteral formulas over 4 h. There were no significant differences in postprandial concentrations of blood glucose among the formulas. The area under the curve of postprandial insulin values, however, was significantly smaller after consumption of the fructose-containing formula (1948 +/- 285 microU min ml-1, P < 0.05) than after fiber-free (3222 +/- 678 microU min ml-1) or two fiber-containing products (2664 +/- 326 microU min ml-1, P < 0.05; and 3040 +/- 708 microU min ml-1, P < 0.05). The insulin area of the xylitol-containing formula (2307 +/- 364 microU min ml-1) was significantly smaller compared to the fiber-free product (P < 0.05). In addition, we found the postprandial increase in triglycerides to be significantly higher after the xylitol-containing formula (from 0.93 +/- 0.14 to 1.25 +/- 0.22 mmol/l) than after the fiber-free product (from 0.82 +/- 0.13 to 0.97 +/- 0.16 mmol/l, P < 0.05) or the two fiber-containing products (from 0.88 +/- 0.16 to 0.96 +/- 0.18 mmol/l, P < 0.05; and from 0.80 +/- 0.08 to 0.95 +/- 0.10 mmol/l, P < 0.05). We conclude that a patient with type II diabetes may benefit from replacing glucose and glucose-equivalent carbohydrates with fructose or xylitol.

Adult↗
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

The fetal mandible measurement: an objective determination of fetal jaw size.

The sonographic diagnosis of micrognathia has been limited by the lack of an objective measurement of the fetal mandible. A cross-sectional study of 134 normal patients of known gestational age between 14 and 39 weeks' gestation was performed. Models to predict mandible length based on gestational age, biparietal diameter, head circumference or femur length were derived by least squares regression analysis. The 95% prediction limits were also derived. Utilization of these curves generated from a normal population should allow for a more sensitive and reproducible method to diagnose micrognathia in the fetus.

Journal Article↗