Showing papers by "Leibniz University of Hanover published in 1992"
TL;DR: In this paper, a new process of nitrification/denitrification via nitrite wais found to be available in half-technical experiences with high operation security, where the essential parameter for regulating the process is the concentration of free ammonia in the reactor.
378 citations
TL;DR: It is concluded that anti-LKM1 is specific for type 2 autoimmune hepatitis and is infrequent in adult patients seen at a referral center in the United States for chronic active hepatitis.
205 citations
TL;DR: In this paper, the authors tested the validity of GIBRAT's Law of proportionate growth and found that the law is only valid for very few groups of firms in some of the periods covered.
Abstract: Using data for some 7000 manufacturing establishments from Lower Saxony for 1978–1989 we tested for the validity of GIBRAT's Law of Proportionate Growth. We found that the law is only valid for very few groups of firms in some of the periods covered. However, we did not find that small firms grew systematically faster or slower than larger firms, or vice versa. On the other hand, we found ‘persistence of chance’ in the sense that a firm grows faster if it happened to grow faster in the past, too.
188 citations
TL;DR: In this paper, a semipreparative HPLC method has been developed isolating carnosic acid among other phenolic diterpenes, identified by 13C-nuclear magnetic resonance (NMR), 1H-NMR, mass and IR spectroscopy.
Abstract: The phenolic diterpene carnosic acid appears to be the main substance for general oxidation leading to artifacts with gamma- or delta-lactone structure in extracts of Rosmarinus officinalis and Salvia officinalis. Until now it was only possible to prepare carnosic acid by hydrogenolysis of carnosol. A semipreparative HPLC method has been developed isolating carnosic acid among other phenolic diterpenes. The separated substances were identified by 13C-nuclear magnetic resonance (NMR), 1H-NMR, mass and IR spectroscopy. Conversion of carnosic acid and carnosol to other phenolic diterpenes was investigated by HPLC.
148 citations
TL;DR: There are two MHC-linked susceptibility factors for Caucasian SLE patients carried by the haplotypes B7-DR2 and B8-DR3, and the results argue against C4Q0 alleles being the decisive factors increasing susceptibility to SLE.
Abstract: In a multicenter study more than 300 central European systemic lupus erythematosus (SLE) patients were examined for HLA-B, HLA-DR, and complement C4 phenotypes. For 174 SLE patients MHC haplotypes were determined by family segregation analysis, and for 155 patients C4 gene deletions were determined by TaqI restriction fragment length polymorphism. Two haplotypes, B8-C4AQ0-C4B1-DR3 and B7-C4A3-C4B1-DR2, were identified as risk factors for SLE. These findings were confirmed by applying the haplotype frequency difference (HFD) method, which uses nontransmitted haplotypes from the family study as internal controls. Furthermore, only HLA-DR2, but not DR3, B7, or B8, was significantly increased in SLE patients independently of the two risk haplotypes. C4A gene deletions, but not silent C4AQ0 alleles, were increased in SLE patients and neither C4BQ0 alleles nor C4B gene deletions were increased. The observed frequencies of homozygosity and heterozygosity for the two haplotypes and the frequencies of homozygotes for C4AQ0 and C4A deletions did not differ from the expected values, indicating that the risk for SLE is conveyed by single allele effects. In conclusion, there are two MHC-linked susceptibility factors for Caucasian SLE patients carried by the haplotypes B7-DR2 and B8-DR3. The results argue against C4Q0 alleles being the decisive factors increasing susceptibility to SLE.
145 citations
TL;DR: In this paper, short-term effects of Al on plasma-membrane integrity of soybean ( Glycine max L.) roots using different physiological/biochemical parameters were investigated.
130 citations
TL;DR: To determine the concentration of individual phenolic diterpenes in pure extracts and fats an HPLC method with electrochemical detection has been developed.
Abstract: The strong antioxidative activity of Rosmarinus officinalis and Salvia officinalis is caused by phenolic diterpenes. Extracts of these herbs are used as additives to stabilize fat and fat-containing foodstuffs against oxidation. To determine the concentration of individual phenolic diterpenes in pure extracts and fats an HPLC method with electrochemical detection has been developed.
125 citations
TL;DR: This first German soft tissue sarcoma (STS) study, CWS‐81, 344 patients younger than 19 years of age who had previously untreated soft tissue Sarcoma were studied, and there were 218 patients with chemosensitive STS who could be studied for a minimum potential follow‐up time of 6 years.
Abstract: Background In the first German soft tissue sarcoma (STS) study, CWS-81, 344 patients younger than 19 years of age who had previously untreated soft tissue sarcoma were studied. For this analysis, there were 218 patients with chemosensitive STS (Group A: rhabdomyosarcoma [RMS], synovial sarcoma, extraosseous Ewing sarcoma, leiomyosarcoma, undifferentiated sarcoma, and malignant peripheral neuroectodermal tumor) who could be studied for a minimum potential follow-up time of 6 years. Methods A staging system based on the postoperative extent of the disease was used. The chemotherapy for Stage I-III disease consisted of vincristine, dactinomycin, cyclophosphamide, and doxorubicin (VACA). Patients with metastatic disease and patients with Stage III disease who failed to respond to VACA were given ifosfamide instead of cyclophosphamide. The definitive procedure for local tumor control (either no radiation exposure, 40 Gy, or 50 Gy) for patients with Stage II-III disease depended on the tumor status at second-look surgery after 16 weeks of chemotherapy. Results The rates of disease-free survival (DFS) and survival after 5 years was 61% +/- 4% and 57% +/- 4%, respectively, in group A; for patients with nonmetastatic tumors (Stages I-III), the rates were 69% +/- 4% and 72% +/- 4, respectively. Patients with nonmetastatic rhabdomyosarcoma had a similar prognosis: the survival rate was 73% +/- 4%, and the DFS rate was 68% +/- 4%. There was no difference in prognosis between patients with Stage I and and those with Stage II disease (DFS rate, 88% +/- 5% and 88% +/- 6%, respectively). The DFS rate for patients with Stage III disease was 54% +/- 5% and for those with Stage IV, 11% +/- 5%. Lack of local tumor control was the primary cause of therapy failure: 10% of patients with localized disease did not achieve complete remission, whereas 18% who were in complete remission experienced local relapse. The most important prognostic factors were tumor size (P = 0.005) and the degree of tumor regression after primary chemotherapy (P = 0.007). The prognosis also differed according to primary site: paratesticular tumors had the best prognosis, whereas tumors located in the parameningeal regions of the head and neck had the worst prognosis (DFS rate, 96% +/- 4% versus 49% +/- 7%, respectively). Conclusions The following conclusions were drawn from the CWS-81 study: (1) intensive chemotherapy (VACA for 35 weeks) provides long-term control for most patients with Stage I-II disease; (2) patients with primary unresectable tumors (i.e., Stage III) who achieve complete remission with chemotherapy alone have the same prognosis as patients with postoperative disease of Stages I and II; (3) tumor size and the degree of tumor regression after primary chemotherapy influence outcome and thus can be used as a basis for risk-adapted therapy.
123 citations
TL;DR: In this paper, the authors reported the observation of a strain transient at the divergent (spreading) plate boundary in Iceland, and used a simple one-dimensional model with a thin elastic layer overlying a viscous layer, which yields a stress diffusivity of 1.1 a±0.3 m2s−1.
Abstract: INTERACTION of the elastic lithosphere with the underlying anelastic asthenosphere causes strain to propagate along the Earth's surface in a diffusion-like manner following tectonism at plate boundaries. This process transfers stress between adjacent tectonic segments and influences the temporal tectonic pattern along a plate boundary. Observations of such strain transients have been rare, and have hitherto been confined to strike-slip and underthrusting plate boundaries1. Here we report the observation of a strain transient at the divergent (spreading) plate boundary in Iceland. A Global Positioning System survey undertaken a decade after an episode of dyke intrusion accompanying several metres of crustal spreading reveals a spatially varying strain field with the expected diffusion-pulse shape and an amplitude three times greater than the 5.7 cm that would be expected from the average spreading rate2. A simple one-dimensional model with a thin elastic layer overlying a viscous layer fits the data well and yields a stress diffusivity of 1.1 a±0.3 m2s−1. Combined with struc-tural information from magnetotelluric measurements, this implies a viscosity of 0.3−2 × 1019 Pa s—a value comparable to that derived for Iceland from post-glacial rebound23, but low compared with estimates for mantle viscosity obtained elsewhere3.
121 citations
TL;DR: The concentration of phenolic diterpenes in commercially available extracts ofRosmarinus officinalis (rosemary) determined by HPLC with electrochemical detection ranged from 2.8 to 22.5% as discussed by the authors.
Abstract: The concentration of phenolic diterpenes in commercially available extracts ofRosmarinus officinalis (rosemary) determined by HPLC with electrochemical detection ranged from 2.8 to 22.5%. Antioxidant activity of extracts under simultaneous storage and thermal stress depended directly on the concentration of phenolic diterpenes. Differences in rates of degradation of individual phenolic diterpenes at different temperatures wre obtained.
113 citations
TL;DR: A first linkage map for beets based on RFLP, isozyme and morphological markers is established and a relatively high degree of polymorphism was found within sugar beet; 47% of the DNA markers were polymorphic for the chosen population.
Abstract: We have established a first linkage map for beets based on RFLP, isozyme and morphological markers The population studied consisted of 96 F2 individuals derived from an intraspecific cross As was expected for outbreeding species, a relatively high degree of polymorphism was found within sugar beet; 47% of the DNA markers were polymorphic for the chosen population The map consists of 115 independent chromosomal loci designated by 108 genomic DNA probes, 6 isozyme and one morphological marker The loci cover 789 cM with an average spacing of 69 cM They are dispersed over nine linkage groups corresponding to the haploid chromosome number of Beta species Eighteen markers (154%) showed distorted segregation which, in most instances, can be explained by gametic selection of linked lethal loci The application of the linkage map in sugar beet breeding is discussed
TL;DR: In this paper, the effect of light on the formation of brown speckles by high Mn concentrations and non-constitutive callose in leaves was evaluated in cowpea.
Abstract: In cowpea typical Mn toxicity symptoms are brown speckles on mature leaves representing depositions mainly in the cell walls and formation of non-constitutive callose. The histochemical charecterization of the brown speckles indicates the presence of oxidized Mn. However, the reducing agent hydroxylamine hydrochloride only slightly while thioglycolic acid almost completely decolorized the speckles. Brown boron-deficient roots treated with hydroxylamine hydrochloride and thioglycolic acid showed the same pattern of decoloration suggesting that the brown color of the Mn toxicity symptoms derives mainly from oxidized phenolics. To evaluate the effect of light on the formation of brown speckles by high Mn concentrations and non-constitutive callose in leaves, three approaches were used: (i) comparison of shaded and unshaded plants at different Mn supplies via the roots, (ii) local application of Mn to leaves in the light and in the dark, (iii) local application of Mn to leaves in the dark with subsequent light and dark treatments. Shading of whole plants (i) aggravated formation of both brown speckles and callose at similar Mn concentrations in the leaves. When the Mn application and the light treatments were locally confined (ii, iii), light had no effect on formation of either brown speckles or callose. The present results are in contradiction to the available reports in the literature showing aggravation of Mn toxicity by high light intensities.
TL;DR: In this paper, the authors investigated self-sustained oscillations due to dry friction in engineering systems and showed that chaotic motions are also possible, depending on the system parameters.
Abstract: Self-sustained oscillations due to dry friction often occur in engineering systems, cf. Magnus [1]. One example, the phenomenon of machine tool chattering which deteriorates the production quality and increases the tool wear is — at least partly — caused by friction forces with a decreasing characteristic. Another phenomenon is the curving noise of tram wheels, induced by nonlinear slip forces, which annoys passengers and city dwellers. Recent investigations of oscillations induced by dry friction show that beside the well-known limit cycle behaviour, chaotic motions are also possible, depending on the system parameters.
TL;DR: Observations suggest that PNET can be induced after completion of the embryonal and fetal development of the human CNS and on‐cogene‐activating point mutations may represent a pathogenetic mechanism involved in the genesis of radiation‐induced brain tumors.
Abstract: Three patients had supratentorial malignant brain tumors 7 to 9 years after prophylactic central nervous system (CNS) treatment for acute lymphocytic leukemia or malignant T-cell lymphoma. Therapy was administered at the age of 3 to 8 years and included cranial irradiation (total dose, 1800 to 2400 cGy) and intrathecal methotrexate. The brain tumors had histologic and immunohistochemical features of primitive neuroectodermal tumors (PNET), including neuroblastic rosettes, rhythmic arrangement of tumor cells, and immunohistochemical expression of glial, and in one patient neuronal, marker proteins. Using polymerase chain reaction-mediated DNA amplification from paraffin-embedded tissues and subsequent DNA sequence analysis, an activating point mutation was detected in the K-ras protooncogene in one tumor. This mutation was a G to A transition in position 2 of codon 12, substituting aspartate (GAT) for glycine (GGT). This type of mutation has not been observed before in human brain tumors, but it is frequent in radiation-induced murine lymphomas. These observations suggest that PNET can be induced after completion of the embryonal and fetal development of the human CNS. Oncogene-activating point mutations may represent a pathogenetic mechanism involved in the genesis of radiation-induced brain tumors.
TL;DR: In this article, a first-order phase transition is observed, resulting in the formation of a physisorbed two-dimensional H2O phase (isosteric heat of adsorption qst = 65 kJ/mol).
TL;DR: In this paper, experiments with three lettuce cultivars (Lactuca sativa L. var. capitata L.), significantly differing in nitrate content, were carried out to investigate the reason for differences in Nitrate accumulation.
TL;DR: Callose was spectrophotometrically quantified in order to evaluate whether it could be used as a parameter to identify genotypical differences in Al and Mn tolerance and relative callose concentrations and relative root-elongation rates for these genotypes were significantly negatively correlated.
Abstract: Callose ((1,3)-β-glucan) formation in plant tissues is induced by excess Al and Mn. In the present study callose was spectrophotometrically quantified in order to evaluate whether it could be used as a parameter to identify genotypical differences in Al and Mn tolerance. Mn leaf-tissue tolerance of cowpea and linseed genotypes was assessed using the technique of isolated leaf tissue floating on Mn solution. Genotypical differences in the density of brown speckles on the leaf tissue (Mn toxicity symptoms) correlated closely with the concentrations of callose for both plant species. In cell suspension cultures Mn excess also induced callose formation. However, differences in tolerance of cowpea genotypes using callose formation as a parameter could only be found in cultured cowpea cells if controls cultured at optimum Mn supply showed low background callose. As soon as after 1 h, Al supply (50 µ M) induced callose formation predominantly in the 5-mm root tip of soybean seedlings. Callose concentration in the 0-30 mm root tips was inversely related to the root elongation rate when roots were subjected to an increasing Al supply above 10 µ M. Three soybean genotypes differed in inhibition of root-elongation rate and induction of callose formation when treated with 50 µ M Al for 8 h. Relative callose concentrations and relative root-elongation rates for these genotypes were significantly negatively correlated.
TL;DR: In this article, the forcing mechanisms for Antarctic coastal polynyas and the thermodynamic effects of existing polynya were studied by means of an air-sea-ice interaction experiment in the Weddell Sea in October and November 1986.
Abstract: The forcing mechanisms for Antarctic coastal polynyas and the thermodynamic effects of existing polynyas are studied by means of an air-sea-ice interaction experiment in the Weddell Sea in October and November 1986.
TL;DR: In this article, an optical sensor has been developed in order to monitor the cutting capacity of grinding wheels, which is based on the principle of triangulation and is mounted at the opposite side of the working area of an external grinding machine.
TL;DR: The application of load-oriented manufacturing control in industry can be found in this article, where the authors propose a load-aware manufacturing control system for the production planning and control of the industry.
Abstract: (1992). Application of load-oriented manufacturing control in industry. Production Planning & Control: Vol. 3, No. 2, pp. 118-129.
Journal Article•
TL;DR: Over a period of 5 months, 18 patients with one or more cracked teeth were treated, and mandibular first molars and maxillary premolars were the teeth most frequently affected.
Abstract: Over a period of 5 months, 18 patients with one or more cracked teeth were treated. Mandibular first molars and maxillary premolars were the teeth most frequently affected. The least affected teeth were mandibular premolars. Predisposing factors for cracked-tooth syndrome are decreased stability (such as caries or poor cavity design) and overloading of the tooth. Treatment involves initial reinforcement and a circumferential cast restoration.
TL;DR: In this paper, a force model is presented for the description of the two-nucleon system below and above pion threshold and its coupled inelastic channels with one pion.
TL;DR: Anticardiolipin antibodies (aCL) and HLA-DR antigens were determined in 314 central European patients with systemic lupus erythematosus and aCL were significantly associated with DRw53.
Abstract: Anticardiolipin antibodies (aCL) and HLA-DR antigens were determined in 314 central European patients with systemic lupus erythematosus (SLE) Both HLA-DR4 and DR7 were increased in aCL-positive patients, and aCL were significantly associated with DRw53The association between DRw53 and aCL was also apparent in those 17 patients with SLE and the anticardiolipin syndrome There was no association between aCL and HLA-DQ or C4 alleles in SLE
TL;DR: It is concluded that in preterm infants requiring mechanical ventilation for any reason of lung insufficiency, ventilation at 60 cycles/min and short IT significantly reduces EAL or prior death compared with 30 cycles/Min and a longer IT of 1s.
Abstract: Two different ventilation techniques were compared in a seven-centre, randomised trial with 181 preterm infants up to and including 32 completed weeks gestational age, who needed mechanical ventilation because of lung disease of any type. Technique A used a constant rate (60 cycles/min), inspiratory time (IT) (0.33s) and inspiratory: expiratory ratio (I∶E) (1∶2). The tidal and minute volume was only changed by varying peak inspiratory pressure until weaning via continuous positive airway pressure. Technique B used a lower rate (30 cycles/min) with longer IT (1.0s). The I∶E ratio could be changed from 1∶1 to 2∶1 in case of hypoxaemia. Chest X-rays taken at fixed intervals were evaluated by a paediatric radiologist and a neonatologist unaware of the type of ventilation used in the patients. A reduction of at least 20% in extra-alveolar air leakage (EAL) or death prior to EAl was supposed in infants ventilated by method A. A sequential design was used to test this hypothesis. The null hypothesis was rejected (P=0.05) when the 22nd untied pair was completed. The largest reduction in EAL (−55%) was observed in the subgroup 31–32 weeks of gestation and none in the most immature group (<28 weeks). We conclude that in preterm infants requiring mechanical ventilation for any reason of lung insufficiency, ventilation at 60 cycles/min and short IT (0.33s) significantly reduces EAL or prior death compared with 30 cycles/min and a longer IT of 1s. We speculate that a further increase in rate and reduction of IT would also lower the risk of barotrauma in the most immature and susceptible infants.
TL;DR: The p(1×1) structure with CO aligned normal to the surface at temperatures above 35 K has been revealed from polarized infrared spectra, measured with a high-resolution Fourier transform spectrometer.
TL;DR: A simple, efficient and reliable method for computing bases of sets induced by interpolation conditions by so-called transfer matrices is derived.
TL;DR: The cranially pedicled pharyngeal flap is regarded as an important operative procedure for improving speech results, especially in cleft lip and palate patients.
Abstract: Between 1980 and 1989, 82 velopharyngoplasties have been carried out in the Department of Oral and Maxillofacial Surgery at the Medical University of Hannover. Speech results of 51 of these patients, including 39 patients with cleft lip and palate, could be followed up in the context of a clinical follow-up examination. Besides evaluation of speech results by two senior speech pathologists and two untrained listeners, a frequency analysis of the speech results with a sonograph was obtained. Nasal air loss was documented with a fogged-mirror test and computer aerometry. Whereas in 37 of 51 patients a normal or almost normal colloquial speech could be demonstrated, 30 of 39 patients with cleft lip and palate showed a normal or almost normal realization of the test sentences. Thirty of the 37 patients (81.08 percent) with normal or almost normal colloquial speech showed extensive mobility of the lateral pharyngeal wall. Symmetry of the velopharyngeal flaps seemed to have no influence on the speech result. With a fogged-mirror test, an average reduction of mirror fogging from 2.0 rings preoperatively to 0.9 rings postoperatively could be shown. In 31 patients, there was no longer any air loss postoperatively. Besides one rupture of a flap, two flaps had to be diminished in their lateral dimensions because of excessive size. We regard the cranially pedicled pharyngeal flap as an important operative procedure for improving speech results, especially in cleft lip and palate patients.
TL;DR: Nine different monosomic additions in Beta vulgaris from Beta webbiana were characterized through morphological characters and isozyme markers, and nine morphotypes could be distinguished.
Abstract: Nine different monosomic additions in Beta vulgaris from Beta webbiana were characterized through morphological characters and isozyme markers. The effect of the alien chromosome on the morphology of the recipient species is chromosome specific, and nine morphotypes could be distinguished. The added chromosome caused a growth reduction in the recipient plants. Eleven isozyme systems were used as marker systems. A 6PGDH band was found as a marker for chromosome 7, which contains a resistance gene for the beet cyst nematode in monosomic additions from Beta procumbens and Beta webbiana. A difference in the 6PGDH zymogram pattern between the two species with respect to this chromosome has been noted.
TL;DR: The results of a preliminary study and a clinical trial of a 2.0 mm titanium miniplate system are presented and the therapeutic consequences of the lesser stability afforded by small plate systems are discussed.
Abstract: Miniplate systems are often used instead of more rigid systems for the treatment of mandibular fractures. While the most stable fixation method for all mandibular fractures is the 2.7 mm plate, most fracture sites and types are eminently suitable for miniplate fixation via an intraoral approach. However, the relatively low stability of the miniplate systems compared with rigid plate systems limits the indications for their use in mandibular fracture treatment, especially when immediate postoperative function is desired. A more rigid miniplate which provides increased stability was studied. The results of a preliminary study and a clinical trial of a 2.0 mm titanium miniplate system are presented in this paper. The therapeutic consequences of the lesser stability afforded by small plate systems are discussed. Indications for miniplate fixation without additional immobilization are reviewed.
TL;DR: Although flow cytometry is not currently an on-line analytical technique, its value as an off-line method is illustrated by examples of the measurement of shear stress effects, lipid content, and sterol content.