Biomedical subjects
Publications and source records attributed to F Weber.
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Presentation of intentions and devices for normofrequency jet-ventilation using N2O/O2-mixture (NFJV/SoSG). Exclusion of Venturi principle permits application of N2O/O2 to anaesthetic ventilation. The conduction of narcosis is analogous to the usual combination anaesthesia. Further advantages of method: Efficient ventilation and oxygenation (F1O2 = 0.25...0.33); minimal need of space for ventilating system; optimal and variable working conditions for the endoscopist; small economic expense. In case of undisturbed gas backflow are hazardous peak pressures excluded. In comparison with ventilation using Carden tube or HFPPV/pneumatic valve principle the NFJV/SoSG appears at the very least equivalent; in important points (need of space at small tracheal diameters; tracheal stenosis) NFJV/SoSG is superior these methods.
In contrast to prokaryotes, in which strong transcriptional signals can be located within very short DNA segments, typical mammalian enhancers are about 200 base-pairs long. We reasoned that a minimal length of enhancer-active DNA is required for a high transcription rate in higher eukaryotes, and that segments from a single enhancer or from different enhancers might be multimerized or combined to satisfy such a requirement. To test this, enhancer fragments from different viruses were joined in a recombinant simian virus 40 (SV40) and screened for efficiency of viral growth. The 48 combinations tested show that the hypothesis is basically correct. For example, two subfunctional heterologous enhancer fragments can together form a functional enhancer. No enhancer shorter than 84 base-pairs could promote SV40 growth, i.e. in no case did we find a short "superstrong" enhancer segment. To test whether multimerization of a short fragment would result in a strong enhancer, we have synthesized a 50 base-pair enhancer segment derived from Herpesvirus saimiri. One to six copies of this oligonucleotide gave an incremental increase in enhancer activity. We propose, therefore, that mammalian gene regulation is based on a redundancy of information that can be provided either by a combination of different DNA sequence elements, or by multiple copies of the same element. Also, the finding of strong and weak enhancers suggests that in most cases an enhancer is permanently required for transcription of a gene, rather than acting in an all-or-none fashion to establish a transcription complex, after which it becomes dispensable.
The introduction of a lower cost alternative to a film commonly used for megavoltage radiation therapy port films led to a comparison of two films (Kodak X-TL and X-OMAT G) in four metal screen cassette configurations. In addition to determination of H-D curves and point spread functions, images of humanoid phantom sections were obtained and evaluated for clinical "usefulness." The X-OMAT G film-screen combinations compared favorably with the X-TL film combinations with respect to the H-D Curves and point spread functions but there was a slight preference for X-TL film. There were no differences noted whether the film was used in the standard "ready pack" or naked in the cassettes.
The correlation between the position of the greater trochanter and the rate of union of the trochanteric osteotomy was assessed in 85 patients who had unilateral total hip arthroplasty using U-bolt fixation of the trochanter. The position of the trochanter was assessed radiologically immediately after operation and at 3-month intervals for 1 year to ascertain the rate of union of the trochanteric osteotomy. The initial postoperative position of the trochanter was classified as either: group 1, trochanter anatomically reduced; group 2, trochanter reattached with some distal displacement; group 3, superomedial tilt of the trochanter (ie, loss of contact with the femoral shaft distally); or group 4, combination of distal displacement and superomedial tilt of the trochanter. The original reduction of the greater trochanter appears to influence its rate of union to the femoral shaft directly. Anatomic reduction or slight distal overlap of the trochanter resulted in union of the osteotomy within 6 months. Fixation of the trochanter in a tilted position invariably led to a delay in union and in nine cases (10.6%) led to a nonunion.
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Three separate studies were carried out to test the hypothesis that rat liver secretes vitamin E (alpha-tocopherol) within very low density lipoproteins (VLDL). i) When the clearance of plasma chylomicrons (CM) and VLDL was blocked by the administration of Triton WR-1339, alpha-tocopherol concentrations increased linearly with time in both classes of triacylglycerol-rich lipoproteins, although accumulation rates within VLDL exceeded those within CM. For fasted rats, appearance of alpha-tocopherol in VLDL persisted at slightly reduced rates. alpha-Tocopherol and triglycerides in the VLDL fraction responded to Triton WR-1339 administration by coordinate increases. In contrast to the situation in serum, alpha-tocopherol concentrations decreased in the liver following injection of Triton. ii) In order to inhibit the secretion of hepatic lipoproteins containing apolipoprotein B (apoB), rats were fed a diet containing orotic acid. This resulted in a reduction of apoB and alpha-tocopherol concentrations in serum and VLDL, whereas the vitamin E content of liver was increased. iii) In primary cultures of hepatocytes, alpha-tocopherol was secreted into the culture media predominantly within VLDL. We, therefore, conclude that the liver secretes alpha-tocopherol within VLDL and in this way contributes to the maintenance of serum vitamin E concentrations.
The effect of preoperative unspecific immunomodulation with Propionibacterium granulosum KP-45 (P.g.) on postoperative complications and patient survival was evaluated in a prospectively randomized trial in patients with colorectal tumor resection. Patients of the therapy group (n = 51) received at least 3 days before operation an infusion of 10 mg P.g., patients of the control group (n = 49) were not treated at all. The wound infection rate and the number of re-explorations were significantly lower in the therapy group, however, patient survival and tumor recurrence rates were not positively affected by this P.g. pre-treatment.
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3654 general surgical interventions were prospectively registered during a 40 month period. Postoperative complications (wound infection, pneumonia, reoperation, mortality) were recorded and were quantified numerically by a complication score which describes the precise number of complications per ten operations. In this way the risk of a single operation can be monitored continuously and quality control programs can do without classification of operations in clean, contaminated and dirty interventions. The length of postoperative hospital stay and the amount of postoperatively applied antibiotics correlated well with the score.
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We have detected a transcriptional enhancer sequence downstream from the adult beta-globin (beta A-globin) genes of chicken and duck. DNA segments from the beta-globin coding and flanking sequences were cloned into expression vectors containing the SV40 promoter linked to either the T antigen gene or the cat gene. The expression of these genes was measured in a chicken erythroid cell line transfected with the recombinant plasmids. We found that segments located about 400 bp downstream from the poly(A) site of both the chicken and duck beta A-globin genes (and about 1.5 kb upstream from the embryonic epsilon-globin gene) stimulate transcription of the test genes about five-fold. In chicken essentially the same segment was also found by others to act as an erythroid cell-specific enhancer [Hesse et al., Proc. Natl. Acad. Sci. USA 83 (1986) 4312-4316; Choi and Engel, Nature 323 (1986) 731-734]. The sequence containing this enhancer is conserved in evolution. A high degree of homology, reaching 84% in a segment 180 bp in length, was found between chicken and duck despite an evolutionary divergence of 70 myr.
Long-lasting resistance to experimental allergic encephalomyelitis (EAE) was obtained in Lewis rats either by an immunization with complete Freund's adjuvant blended with aluminum hydroxide (ALU-CFA) or by convalescence from EAE. Total body irradiation at a dose of 500 R given both 1 day after ALU-CFA (or disease induction) and EAE challenge did not abrogate the protection. No antibodies against myelin basic protein could be detected in irradiated animals. In contrast high antibody titers were measured in non-irradiated controls recovered from EAE and subsequently resistant to the disease. Therefore it is unlikely that antibodies against myelin basic proteins are of any importance in protection from EAE. The studies suggest that unspecific radioresistant suppressor cells play a role in resistance to EAE.
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Moderate concentrations of ethanol reduce the velocity of uptake of three representative Na+-symport systems (D-glucose, L-alanine, L-ascorbate), whether electrogenic (the first two) or electroneutral (L-ascorbate). This 'inhibition' is observed only if these transport systems are tested in the presence of an initial Na+ gradient (out greater than in); no inhibition is found in tracer-equilibrium exchange measurements. A representative Na+-independent system (D-fructose) is not inhibited by ethanol. 'Passive diffusion' (measured as uptake of L-glucose) is increased somewhat by alcohol. All these observations can be rationalized [as suggested by Tillotson et al. (1981) Arch. Biochem. Biophys. 207, 360-370] by an effect of ethanol on passive diffusion, which leads to a faster collapse of the Na+ gradient, with the resulting reduction of the uptake velocities of Na+-dependent transport systems when tested with the added driving force of an Na+ out----in gradient.
The early transmembrane glycoprotein E19 of adenovirus-2 binds to class I antigens of the major histocompatibility complex (MHC). The association is initiated in the endoplasmic reticulum of infected cells and abrogates the intracellular transport of the class I molecules. To examine which parts of the E19 molecule are responsible for the association with the class I antigens and which parts confine the protein to the endoplasmic reticulum we have constructed a series of mutated E19 genes, which have been expressed in an improved mammalian expression vector. By various manipulations the membrane anchoring and the cytoplasmic domains were removed from the protein. The biosynthesis of the mutant protein was examined. All mutant proteins were secreted from the cells suggesting that the transmembrane and/or cytoplasmic portions of the E19 molecule are responsible for its confinement to the endoplasmic reticulum. The ability to associate with class I antigens was retained by the lumenal domain of the E19 protein.