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Biomedical subjects

H Baumann

Publications and source records attributed to H Baumann.

320 records · Page 18Linked to original sources
PubMedDate not supplied

Uteroplacental blood flow velocity waveforms in the second and third trimesters of normal pregnancy as related to the placenta location.

The systolic/diastolic ratios (A/B) of uteroplacental blood flow velocity waveforms as related to the placenta location were investigated by continuous-wave Doppler ultrasound in 67 normal pregnancies at 18-21 weeks, in 111 at 31-33 weeks, and in 34 at 40-41 weeks of gestation. Using real-time ultrasound, the placenta was located laterally in 48%, posteriorly in 30% and anteriorly in 22% of the pregnancies. A/B values decreased slightly with advancing gestational age. With lateral placenta location, statistically significant higher A/B values were found in vessels on the nonplacental side at 31-33 weeks of gestation (2.07 +/- 0.43 versus 1.74 +/- 0.27; p less than 0.05). In the other gestational age groups there were no statistically significant differences between A/B values in the vessels on the placental and nonplacental sides. There were also no differences in A/B values between left and right uteroplacental vessels with anterior or posterior placenta locations in any of the gestational age groups.

Blood Flow Velocity↗
PubMedDate not supplied

Plasma protease inhibitors in mouse and man: divergence within the reactive centre regions.

The plasma protease inhibitors control a wide variety of physiological functions including blood coagulation, complement activation and aspects of the inflammatory response. The inhibitors function by forming a 1:1 complex with a specific protease within the reactive centre region of the inhibitor. Little is known about the evolutionary relationships of these inhibitors. We report here the sequences of cDNAs which represent the C-terminal halves of the two major murine plasma protease inhibitors. One of these, murine alpha 1-antitrypsin, more appropriately called alpha 1-proteinase inhibitor (alpha 1-PI), has diverged from its human counterpart at a vital position in the reactive centre but this has not led to a physiologically significant change in function. Also, we have determined the partial sequence of a recently characterized protein termed contrapsin, which inhibits trypsin-like proteases. We show, surprisingly, that contrapsin is highly homologous to human alpha 1-antichymotrypsin, an inhibitor of chymotrypsin-like proteases. The reactive centre regions of these two inhibitors have diverged considerably, which may account for the differences in specificity. We propose that the genes for contrapsin and human alpha 1-antichymotrypsin are the descendents of a single gene that have evolved since rodent and primate divergence to encode proteins with different functions.

Amino Acid Sequence↗
PubMedDate not supplied

Biocompatibility testing of new polymers in a moving implant bed.

Total reconstruction of the auricle requires a skillful surgical technique and an appropriate material for the shape-supporting frame. Up to now, there is no such material apart from autologous rib cartilage. The combination of chronic microtraumatization of adjacent tissue caused by the mobility of an implant bed such as the auricle and the foreign-body reaction to currently available artificial polymers frequently results in extrusion. In our animal model (rats), polymers of different elasticity were implanted in a moving implant bed to analyse differences in foreign-body reaction related to implant elasticity. The results were significantly better for a rather stiff control material (porous polyethylene). A contributing factor may be better fixation of the implant material by tissue ingrowth into its micropores.

Animals↗
PubMedDate not supplied

Aurintricarboxylic acid and polynucleotides as novel inhibitors of ribonucleotide reductases.

Ribonucleoside diphosphate reductases isolated from Escherichia coli, baker's yeast, Ehrlich ascites tumor cells, and unicellular green alga (Scenedesmus obliquus) are inhibited strongly and uniformly by the polymeric triphenylmethane dye, aurintricarboxylic acid. The molecule appears to interact simultaneously with the enzyme's various nucleotide and catalytic (iron-organic radical) sites. Oligo- and polyribonucleotides are also inhibitory. These reactions serve as models of the probably physiologic regulation of ribonucleotide reduction exerted by natural inhibitors. Partial characterization of an inhibitor fraction found in wheat seed embryo is described.

Animals↗
PubMedDate not supplied

[Doppler ultrasound studies before and following short-term maternal stress in late pregnancy].

Ten gravidae with normal course of pregnancy in the third trimester underwent a bicycle stress test (semi-supine, 75 W, 3 min). By means of pulsed Doppler sonography, a lowering of the resistance index (RI) in the maternal femoral artery from 93% to 69% was ascertained, though also a rise in maximum systolic velocity (VMAX (syst)) from 73 cm/sec to 194 cm/sec, in maximum diastolic velocity (VMAX diast)) from 5 cm/sec to 61 cm/sec, and in the time-averaged maximum velocity (TAVMAX) from 20 cm/sec to 101 cm/sec. These changes are statistically significant. In the maternal common carotid artery these parameters remained stable or changed little, for example VMAX (diast), which dropped from 24 cm/sec before to 19 cm/sec after exercise, and the RI, which rose from 77% to 84%. Neither in the uteroplacental vessels nor in the umbilical artery were any changes in the RI found (40% to 42% and 58% to 57%, respectively). The fetal cardiotachograms were normal in all cases, while not all cases manifested a rise in fetal heart rate following maternal stress. These results indicate that uteroplacental perfusion and the umbilical circulation remain constant. Doppler sonography thus demonstrates directly and noninvasively that provided placental function is normal the uteroplacental and fetoplacental circulation are not influenced by moderate physical exertion.

Blood Flow Velocity↗
PubMedDate not supplied

The clinical trial of TOMOTRON--a new electronic device--and eight months' clinical experience.

We have been using digital tomography (TOMOTRON) clinically for eight months. Its advantages include savings in both time and dose, good image quality through increased contrast, and improved magnification and image postprocessing compared with conventional tomography. However, lower image resolution and small image sections are the disadvantages of digital tomography. Weighing these advantages and disadvantages by our experience, the diagnostic accuracy of digital tomography is higher than conventional tomography, particularly in skeletal studies.

Analog-Digital Conversion↗