Structure formation in sugar containing pectin gels - influence of tartaric acid content (pH) and cooling rate on the gelation of high-methoxylated pectin.

The aim of the study was the application of a recently published method, using structuring parameters calculated from dG'/dt, for the characterisation of the pectin sugar acid gelation process. The influence of cooling rate and pH on structure formation of HM pectin gels containing 65 wt.% sucrose were investigated. The results show that the structure formation process as well as the properties of the final gels strongly depended on both parameters. With increasing cooling rates from 0.5 to 1.0 K/min the initial structuring temperature slightly decreased and the maximum structuring velocity increased. The lower the cooling rates, the firmer and more elastic were the final gels. With increasing acid content (decreasing pH from 2.5-2.0) the initial structuring temperatures were nearly constant. The final gel properties varied visibly but not systematically. Gels with the lowest and highest pH were less elastic and weaker compared to those with medium acid concentrations.

[Body-packer & body-stuffer - a medical challenge]. / Body-Packer & Body-Stuffer - eine medizinische Herausforderung.

Since the seventies, the practice of drug smuggling in the form of body packing has increased in the Western world. The goal of our study was to present an algorithm for the safe management of intracorporal drug transport based on clinical experience and current evidence. The retrospective study, conducted over the past four years in our hospital prison, analyzes and discusses the diagnostic and therapeutic concepts. Thirty-four patients hospitalized 37 times in a 48-month period were included. In 28 patients drug packages were identified. Only two patients suffered from serious complications. The study demonstrates that following a specifically designed management algorithm based on clinical experience and principles of evidence-based medicine can optimize risk management, improve quality assurance and patient safety.

Influence of the emulsion components and preparation method on the laboratory-scale preparation of o/w emulsions containing different types of dispersed phases and/or emulsifiers.

Emulsification is a complex process, strongly influenced by emulsion composition as well as by preparation procedure, and the characterisation of emulsions with regard to their structure and stability can be carried out with many different methods. To evaluate the influences of emulsion composition and preparation procedure on the structure and properties, oil-in-water emulsions were prepared using the model dispersed phase dodecane and the surfactant Tween on the one hand and the real food components sunflower oil (dispersed phase) and casein (emulsifier) on the other hand. The emulsions were prepared in a small laboratory-scale with a turbo-mixer alone and in combination with ultrasonic treatment. The emulsion activity was measured by photometry, the emulsion stability was evaluated visually and the droplet size was determined by laser particle analysis. The results of the investigations made with the model substances agree only partly with those made with the real food substances. For the model emulsions strong correlation were found between the emulsion activity and the particle sizer data because of the high purity and the defined structure of the model substances. On the contrary, for the emulsions made with the real food components sunflower oil and sodium caseinate the correlation were much weaker. Therefore a proper characterisation of the structure and properties of food emulsions requires examinations with several methods which are independent from each other. Furthermore, for laboratory-scale emulsification the combination of turbo-mixer and ultrasonic treatment is suitable to obtain small droplets and a narrow droplet distribution also for very small emulsion volumes.

Thermodynamic compatibility of sodium caseinate with different pectins. Influence of the milieu conditions and pectin modifications.

Combinations of pectins and caseins are ingredients of many food products. Therefore the thermodynamic compatibility of both components was examined to investigate the influences of environmental factors as well as of the structure of the pectin. High-methoxyl pectin was demethoxylated and amidated, respectively, and tested for the compatibility with sodium caseinate under varying conditions of pH and ionic strength. The compatibility increased with increasing pH and decreasing ionic strength. Demethoxylated pectins were more and amidated pectins less compatible with the caseinate. Changes in the pectin hydrophilicity, solubility and molecular weight and possibly local interactions such as electrostatic attraction, hydrogen bonding and calcium bridges are involved in the compatibility of the components. The type and degree of the pectin modifications as well as the type, composition and properties of the protein were found to be of great importance for the thermodynamic compatibility.

HPRT mutations in V79 Chinese hamster cells induced by accelerated Ni, Au and Pb ions.

Mutation induction by accelerated heavy ions to 6-TG resistance (HPRT system) in V79 Chinese hamster cells was investigated with Ni (6-630 Me V/u), Au (2.2, 8.7 Me V/u) and Pb ions (11.6-980 Me V/u) corresponding to a LET range between 180 and 12895 ke V/microns. Most experiments could only be performed once due to technical limitations using accelerator beam times. Survival curves were exponential, mutation induction curves linear with fluence. From their slopes inactivation- and mutation-induction cross-sections were derived. If they are plotted versus LET, single, ion-specific curves are obtained. It is shown that other parameters like ion energy and effective charge play an important role. In the case of Au and Pb ions the cross-sections follow a common line, since these ions have nearly the same atomic weight, so that they should have similar spatial ionization patterns in matter at the same energies. Calculated RBEs were higher for mutation induction than for killing for all LETs.

Killing and mutation of Chinese hamster V79 cells exposed to accelerated oxygen and neon ions.

Mutation induction by accelerated heavy ions to 6-thioguanine resistance (HPRT system) in Chinese hamster V79 cells was investigated using oxygen and neon ions with energies between 1.9 and 400 MeV/mu, corresponding to LET values between 18 and 754 keV/microns, respectively. Because of technical limitations most experiments could be performed only once. Inactivation and mutation induction cross sections, sigma i and sigma m, were obtained from the slopes of the exponential survival and the linear mutation induction curves, respectively. Both parameters increased with LET up to about 200 keV/microns, where the curves separated for the two types of ions. Calculated RBEs were higher for mutation induction than for killing for all LET values.

Induction of HPRT- mutants in Chinese hamster V79 cells after heavy ion exposure.

The induction of resistance to 6-thioguanine by heavy ion exposure was investigated with various accelerated ions (oxygen-uranium) up to linear energy transfer (LET) values of about 15,000 keV/microns. Survival curves are exponential with fluence; mutation induction shows a linear dependence. Cross-sections (sigma i: inactivation, sigma m: mutation) were derived from the respective slopes. Generally, sigma i rises over the whole LET range, but separates into different declining curves for single ions with LET values above 200 keV/microns. Similar behaviour is seen for sigma m. The new SIS facility at GSI, Darmstadt, makes it possible to study the effects of ions with the same LET but very different energies and track structures. Experiments using nickel and oxygen ions (up to 400 MeV/u) showed that inactivation cross-sections do not depend very much on track structure, i.e. similar values are found with different ions at the same LET. This is not the case for mutation induction, where very energetic ions display considerably smaller induction cross-sections, compared with low-energy ions of identical LET. Preliminary analyses using the polymerase chain reaction (PCR) demonstrate that even heavy ions cause "small alterations" (small deletions or base changes). The proportion of the total deletions seems to increase with LET.

Mutation induction by heavy ions.

Mutation induction by heavy ions is compared in yeast and mammalian cells. Since mutants can only be recovered in survivors the influence of inactivation cross sections has to be taken into account. It is shown that both the size of the sensitive cellular site as well as track structure play an important role. Another parameter which influences the probability of mutation induction is repair: Contrary to naive assumptions primary radiation damage does not directly lead to mutations but requires modification to reconstitute the genetic machinery so that mutants can survive. The molecular structure of mutations was analyzed after exposure to deuterons by amplification with the aid of polymerase chain reaction. The results--although preliminary--demonstrate that even with densely ionizing particles a large fraction does not carry big deletions which suggests that point mutations may also be induced by heavy ions.

RNA polymerase III catalysed transcription can be regulated in Saccharomyces cerevisiae by the bacterial tetracycline repressor-operator system.

We have investigated whether the RNA polymerase III-driven transcription of eukaryotic tRNA genes can be regulated by the prokaryotic tetracycline operator-repressor system. The bacterial tet operator (tetO) was inserted at two different positions (-7 and -46) upstream of a tRNA(Glu) (amber) suppressor gene. Both constructs are transcribed in Saccharomyces cerevisiae and yield functional tRNAs as scored by suppression of an amber nonsense mutation in the met8-1 allele. Controlled expression of Tet repressor was achieved by fusing the bacterial tetR gene to the yeast gal1 promoter. This leads to expression of Tet repressor in yeast on galactose--but not on glucose--containing media. Regulation of the su-tRNA gene with the tetO fragment inserted at position -7 has been demonstrated. Under conditions which allow tetR expression, cells exhibit a met- phenotype. This methionine auxotrophy can be conditionally reverted to prototrophy by adding tetracycline. However, a su-tRNA gene with the tetO fragment inserted at position -46 cannot be repressed. Our results demonstrate clearly that the bacterial repressor protein binds to its operator in the yeast genome. Formation of this complex in the vicinity of the pol III transcription initiation site reduces the level of su-tRNA at least 50-fold as concluded from quantitative primer extension analyses. This indicates for the first time that class III gene expression can be regulated by a DNA binding protein with its target site in the 5'-flanking region and that a prokaryotic repressor can confer regulation of a suitably engineered tRNA gene.

Mutation induction in mammalian cells by very heavy ions.

V79 Chinese hamster cells were exposed to heavy ions (O to U) and assayed for mutants at the HGPRT-locus by incubation in selective medium containing 6-thioguanine. The LET ranged from 300 to 18000 keV/micrometer. Mutants could be recovered from all particle radiation but the effectivity per deposited energy decreased with atomic numbers greater than 8. The results are discussed with regard to fundamental processes of cell reactions to very heavy ions and with respect to possible implications for hazard estimations.

[Reduction of the incidence of postoperative morbidity after vaginal operations by the choice of suture material (author's transl)]. / Kann die postoperative Morbidität nach vaginalen Operationen durch Verwendung von verschiedenen Nahtmaterialien gesenkt werden?

Dexon suture material is capable of lowering the postoperative morbidity. Among 142 vaginal operations for prolapse 82 were done with catgut and 60 with Dexon. In the catgut group 24.4% had a temperature of 37.5 or higher for more than one day and 15.0% in the Dexon group. Secondary vaginal bleeding occurred in 15.8% of the catgut patients and in 6.6% of the Dexon patients. The mean hospital stay was 18.8 days after operations with catgut and 14.6 days after operations with Dexon. There were less wound dehiscences than in the group operated with catgut. Dexon has higher tensile strength than catgut. It is absorbed by hydrolysis and causes less tissue reaction. Dexon shows the desirable properties of both an absorable and a nonabsorbable suture material.