Reversible mass exchange between two multicomponent systems of different temperatures.

The concept of reversible work in nonequilibrium systems, which has been used for the derivation of thermal diffusion coefficients, is critically examined. For this purpose heat and mass exchange between two multicomponent systems of different temperatures and pressures is treated in detail. It is shown both by general considerations and by a specific example that calculating the reversible work--the work performed in case of reversible mass exchange--is essentially the same as calculating the dissipation function describing the corresponding irreversible process. Although the dissipation function is the starting point for the description of irreversible processes in nonequilibrium thermodynamics, it is not obvious how it could be used to obtain an expression for the thermal diffusion coefficient.

[Intersectoral collaboration of institutions in Germany and Europe in the field of food-borne zoonoses]. / Zusammenarbeit nationaler und europäischer Behörden im Bereich lebensmittelbedingter Zoonosen.

Prevention and control of food-borne zoonoses is given high priority in Germany and in the European Union. To implement targeted control measures, detailed data are necessary on human zoonoses and on the prevalence of zoonotic agents along the food chain. EU-wide legislations have been stipulated that allow collection and collation of relevant data across member states. The necessary structures have been established and are being constantly refined. In addition, surveillance systems and early warning systems have been improved or set up, respectively, to timely investigate and control food-borne outbreaks and to transnationally communicate food safety risks. For prevention and control to be effective, well-defined responsibilities and close collaboration of public health, veterinary public health and food safety authorities are needed. This report reviews the pertinent legislation, the established structures, and the collaboration of competent authorities in Germany and particularly in Europe. In the future, data quality and collaboration on national and EU levels will likely be further improved. Targeted control measures, particularly at primary production, are expected to lead to a sustainable reduction of the incidence of food-borne zoonoses.

A second look at the influence of birth weight on carcass and meat quality in pigs.

To re-examine the relationship of birth weight with carcass and meat quality of pigs at market weight, offspring (n=378) of 63 sows were assigned to three birth weight groups; 25% low weight (LW), 50% middle weight (MW), and 25% heavy weight (HW), with runts (<800g) being excluded. LW pigs exhibited the lowest postnatal growth performance, the lowest lean mass and the greatest degree of fatness in terms of perirenal fat compared with MW and HW pigs. Only in females, but not in male castrates, the lean percentage was highest in HW pigs. Characteristics of longissimus muscle technological quality declined either in LW (pH, drip loss) or HW (conductivity, lightness) compared with MW pigs. In contrast, intramuscular fat percentage (IMF) was highest in LW pigs. The results suggest that the most desirable carcass composition is obtained with HW pigs, whereas optimum technological pork quality, except for IMF, is achieved with MW pigs.

Optical cell with periodic resistive heating for the measurement of heat, mass, and thermal diffusions in liquid mixtures.

A new technique for the measurement of heat, mass, and thermal diffusions in liquids has been developed. Similar to laser induced dynamic gratings, a temperature grating is created in the sample. Thermal expansion transforms the temperature into a refractive-index grating, which is read by diffraction of a readout laser beam. In a multicomponent mixture an additional concentration grating is formed by thermal diffusion driven by the temperature gradients of the temperature grating. Differently to laser induced dynamic grating experiments we use Joule heating instead of optical heating. For that purpose we have built cuvettes which have a grating of transparent conducting strips on the inner side of one of their windows. If heated by an electric current a temperature grating will build up in the sample. Both the heat equation and the extended diffusion equation have been solved in two dimensions to allow for quantitative data analysis. Our apparatus and method of analysis have been validated by measurements of heat, mass, and thermal diffusions in pure and binary liquids. Heat diffusion can be correctly determined as was shown for pure toluene, pure dodecane, and the symmetric mixture of isobutylbenzene dodecane. Mass and thermal diffusions were studied in the three symmetric mixtures of dodecane, isobutylbenzene, and tetralin. The obtained diffusion and Soret coefficients agree with the literature values within the experimental errors. Uncompensated transient heating effects limit the resolution of the experimental technique.

Suppression of a hind limb flexion withdrawal reflex by microinjection of glutamate or morphine into the periaqueductal gray in the rat.

Microinjection into the midbrain periaqueductal gray (PAG) or lateral reticular formation (LRF) of the neuronal excitant glutamate produces analgesia, and suppresses the responses of a fraction of spinal dorsal horn neurons to noxious heat applied to ventral hind paw skin. Microinjection of morphine into the PAG also produces analgesia, but has been reported to frequently facilitate, as well as to suppress or have no effect, on nociceptive spinal neurons. In anesthetized rats, we tested whether (a) glutamate microinjections into PAG or LRF, and (b) morphine microinjections into PAG, affected the isometric force of hind limb withdrawal elicited by the same noxious heat stimuli on the hind paw as used in single-unit studies of dorsal horn neurons. Glutamate (0.5 M; 0.1-0.5 microliter) microinjected at 9/12 PAG and 8/10 LRF sites suppressed the reflex, and had no effect or facilitated the reflex from the remaining sites. Morphine (5 micrograms in 0.5 microliter) microinjected at each of 10 PAG sites suppressed the reflex in a naloxone-reversible manner. Suppression usually began shortly after morphine, peaked at 20-40 min, and lasted greater than 60 min. The integrated flexion reflex thus appears to be more susceptible to chemical midbrain stimulation under these experimental conditions, compared to previous studies of single dorsal horn neurons.

The excitation of cutaneous nerve endings in a neuroma by capsaicin.

Spontaneous electrophysiological activity and excitation by capsaicin of regenerating sensory fibers has been studied using 1 to 20-week-old neuromas induced in rats by ligating and transecting the saphenous nerve. Overall, spontaneous activity occurred in 12% of fibers, and capsaicin at concentrations up to 1.0 microM excited 3.8% of all the A delta-plus C-fibers examined. There was a slight increase in the incidence of spontaneous activity, but not excitation by capsaicin, with increasing age of the neuromas. The responses to capsaicin were similar to those seen with normal saphenous nerve endings, including bursting discharges and desensitization with repeated applications. The results are considered in the context of the requirements for reexpression of normal sensory capacities on regenerating sensory nerve endings.

Analyses of spontaneous mutations of cloned gene 49 of phage T4.

Holliday structure resolving enzyme endonuclease VII (endo VII) of phage T4 is highly toxic for E. coli when expressed outside of the phage infection environment. As a consequence, plasmids with a mutated gene 49, the gene which encodes for endo VII, can be easily isolated and characterised. We have isolated and characterised 400 survivors from independent transformations with a plasmid carrying gene 49 under the control of the T7 promoter. The majority had mutated gene 49 by IS10 insertions which almost exclusively mapped to a distinct site. When this site was mutated other insertion sites were observed as well as an increase in other mutational events including large deletions. Neither of the observed insertion sites mapped matched the consensus IS10 sequence completely. Additionally when the level of expression of gene 49 was altered the distribution of mutations was changed suggesting that other elements apart from the target sequence are necessary for determining IS10 insertion. The expression of gene 49 in E. coli provides a particularly useful tool for the analysis of mutational events.

Sequential changes in the nucleoli of human spermatogonia with special reference to rDNA location and transcription.

The nucleoli of human spermatogonia were studied using electron microscopy, silver staining, radioautography and in situ hybridization. In all types of A spermatogonia, nucleoli were consistently located at the periphery of the nucleus and contained a single fibrillar center associated with the nuclear envelope. In B spermatogonia, nucleoli were centrally located in the nuclei and showed several fibrillar centers or were found to disintegrate. Nucleolar morphology was found to be a good, though not an unequivocal indicator of spermatogonial type. The observed changes in nucleolar morphology reflect the differentiation of spermatogonia: the nucleolar disintegration seen in B spermatogonia corresponds to a pre-leptotene cessation of rDNA transcription. In radioautographs following 3H-uridine uptake, the label was consistently found over the dense fibrillar component, except in the B spermatogonia with disintegrating nucleoli, where no uptake could be detected. In situ hybridization demonstrated that the distribution of rDNA did not correspond to the site of the fibrillar center but to the dense fibrillar component. Compared with radioautographs, this finding clearly established that transcribed units of rDNA were located in the dense fibrillar component. Silver staining was strongly positive in fibrillar centers and in the dense fibrillar component. In Ap spermatogonia the silver deposit was often localized at the edge of the fibrillar threads. The relationships between silver-stained proteins and transcribed and nontranscribed portions of ribosomal genes are reevaluated.

Yersinia in effluents from the food-processing industry.

Yersinia enterocolitica and Yersinia pseudotuberculosis are current sources of pathogenic strains in humans and animals. Yersiniae infections occur throughout the world, but are most prevalent in regions with moderate and subtropical climates. In Australia, Central Europe and North America, cases of human infections with Yersinia enterocolitica now rank in third place. The food-processing industry may influence the epidemiological situation in different ways. Effluents which contaminate the environment may originate from slaughterhouses; e.g. from sewage contaminated with faeces from the lairage or contaminated effluents from the actual slaughter areas. The carcasses may serve as carriers of the organisms to the food-processing plants where they eventually contaminate the processed foods. Rodents and pests may also be carriers. Pathogenic Y. enterocolitica and Y. pseudotuberculosis strains mainly occur in swine and pork. The ability to multiply under refrigeration and in vacuum-packaged products means that pathogenic Y. enterocolitica can cause foodborne diseases. If a plant harbours any pathogenic Yersiniae, transfer of the contaminant to the sewage is possible. Although pathogenic Yersiniae from infected animals can survive in sewage and in surface waters, the role of properly treated sewage in the transmission of yersiniosis seems to be of minor importance. If the recommendations for modern slaughter techniques are properly followed, the spread of pathogens in the slaughterhouses and, subsequently, into other food-processing plants can be minimised.

Advances in light curing.

PURPOSE: To review and connect the scientific background of light curing with clinical requirements and new technical opportunities in order to conclude the best technology for next generation light curing units. RESULTS: Three conclusions are drawn for proper light curing: (1) A minimum dose of light is needed (wavelength dependent); (2) Internal stress can be reduced by giving the sample time to flow before gel point is reached; (3) An upper intensity limit has to be respected to limit temperature increase as well as light intensity dependent deactivation of activated photoinitiators. These conclusions can best be realized by using the softstart approach. A comparison of different light generation technologies shows that LEDs are most likely to shape the next generations of curing lights. Due to their superior power conversion rate as well as to their optimum spectral emission small and handy devices can be realized that work battery-powered and totally silent. The benefits for the dentist are improved reliability, handling, and hygiene.

[Occurrence of enteritis-causing salmonellae in food and in domestic animals in 1991]. / Vorkommen von Enteritis-Salmonellen in Lebensmitteln und bei Nutztieren 1991 (Kurzmitteilung).

The control of salmonellae in foods and animals in Germany, 1991, is based on voluntary contributions of veterinary institutions, e. g. governmental investigation centres, universities, agricultural institutions and slaughter-house laboratories. The results of questionnaire-based evaluations are presented (s. a. HARTUNG, 1993 a). Also reported were 101 outbreaks involving 2272 cases of salmonellosis (fig. 1), of which 92% were caused by S. enteritidis. 46% of the cases were caused by egg and egg-containing meals, 24% by bakery products, often containing raw eggs. From poultry meat the organism was only isolated in less than 1% of the known cases. Meat and meat products (10%) and milk (5%) were further sources of infection. Summarizing it can be assumed that in 70% of the cases the cause of foodborne salmonellosis were meals prepared with raw eggs. The mean salmonella rate in routine food investigations was 0.88% (tab. 1). Poultry had a salmonella rate of 13% and eggs, incl. egg-containing dishes, a rate of 1%. All other food groups were contaminated with salmonella at the level of the mean rate (meat and meat products) or less (fish and milk and their products: 0.1%). The mean salmonella rate in diagnostic examinations of domestic animals was 5.77% (tab. 2). Cattle and chicken showed salmonella rates at the level of the mean rate, whereas pig, sheep, goats and equines showed much lower levels. On the other hand "other poultry" (9.5%) and especially chicks (13%) had higher levels of salmonella.(ABSTRACT TRUNCATED AT 250 WORDS)

Quo vadis? - Monitoring Campylobacter in Germany.

Campylobacter is a poorly recognized foodborne pathogen, leading the statistics of bacterially caused human diarrhoea in Europe during the last years. In this review, we present qualitative and quantitative German data obtained in the framework of specific monitoring programs and from routine surveillance. These also comprise recent data on antimicrobial resistances of food isolates. Due to the considerable reduction of in vitro growth capabilities of stressed bacteria, there is a clear discrepancy between the detection limit of Campylobacter by cultivation and its infection potential. Moreover, antimicrobial resistances of Campylobacter isolates established during fattening of livestock are alarming, since they constitute an additional threat to human health. The European Food Safety Authority (EFSA) discusses the establishment of a quantitative limit for Campylobacter contamination of broiler carcasses in order to achieve an appropriate level of protection for consumers. Currently, a considerable amount of German broiler carcasses would not comply with this future criterion. We recommend Campylobacter reduction strategies to be focussed on the prevention of fecal contamination during slaughter. Decontamination is only a sparse option, since the reduction efficiency is low and its success depends on the initial contamination concentration.

Correlation between thermal diffusion and solvent self-diffusion in semidilute and concentrated polymer solutions.

We have performed measurements of thermal diffusion coefficients DT and solvent self-diffusion coefficients Dss in semidilute to concentrated polymer solutions. Solutes of different glass transition temperatures and solvents of different solvent qualities have been used. The investigated systems are in detail: poly(dimethyl-siloxane) in toluene, tristyrene in toluene, polystyrene in toluene, polystyrene in tetrahydrofuran, polystyrene in benzene, and polystyrene in cyclohexane. The thermal diffusion data are compared to our data and literature data for solvent self-diffusion coefficients. In all systems the concentration dependence of DT closely parallels the one of Dss which may be viewed as a local probe for friction on a length scale of the size of one polymer segment. This identifies local friction as the dominating parameter determining the concentration dependence of DT. Solvent quality, in contrast, has no influence on DT.

Thermal diffusion of dilute polymer solutions: the role of solvent viscosity.

We have performed measurements of the thermal diffusion coefficient D(T) in the dilute limit on polystyrene in cyclo-octane, cyclohexane, benzene, toluene, tetrahydrofuran, ethyl acetate, and methyl ethyl ketone and of poly(dimethyl-siloxane) in toluene. These data have been combined with literature data to test various theoretical predictions. The viscosity is identified as the dominating and only relevant solvent parameter. On the polymer side, the size or mass of an effective correlated segment determines the strength of the Soret effect. Large and heavy effective segments, as found in stiffer chains, lead to higher D(T).

The role of heat-conducting walls in the measurement of heat and mass transport in transient grating experiments.

We present a two-dimensional model to account for the role of heat-conducting walls in the measurement of heat transport and Soret-effect--driven mass transport in transient holographic grating experiments. Heat diffusion into the walls leads to non-exponential decay of the temperature grating. Under certain experimental conditions it can be approximated by an exponential function and assigned an apparent thermal diffusivity D(th, app)

[Malignant diseases of the inner nose--epidemiology and occupational medicine aspects]. / Bösartige Erkrankungen der inneren Nase--Epidemiologie und arbeitsmedizinische Aspekte.

Squamous cell carcinomas are the most frequent malignancies of the inner nose, followed by adenocarcinomas, adenoid cystic carcinomas, and other malignant neoplasms. Carcinomas of the nose can be recognized as occupational diseases if there has been a professional exposition to ionizing rays, certain arsenic compounds, hexavalent chrome compounds, nickel, oak or beech wood dust. The sources of danger relevant in industrial medicine are indicated. At present, adenocarcinomas induced by dust of wood are of special significance: 16 out of 22 carcinomas of the nose recognized as occupational diseases between 1978 and 1986 are due to oak and beech wood dust.

Examination of 20 Bacillus species by crossed immunoelectrophoresis under taxonomic aspects.

In order to examine the efficiency of crossed immunoelectrophoresis (CIE) for the differentiation of species and for the determination of taxonomic relationships within the genus Bacillus, an investigation including strains of 20 species was performed. Ultrasonic extracts (USE) of sporefree-grown vegetative cells were used. With rabbit antisera against USE of type strains, the CIE was accomplished in homologous and heterologous combinations. USE's of additional strains were included into this investigation. In order to evaluate the immunoelectropherograms, the number of precipitates was counted. A mean of 103 precipitates was found in homologous reactions. With few exceptions, heterologous combinations showed less similarity in the number of antigens. Because of their high cross-reactions, the following species could not be differentiated: B. subtilis from B. amyloliquefaciens and strains of B. coagulans, furthermore, B. cereus from B. thuringiensis. The different species revealed lower numbers of precipitates with decreasing taxonomic relationships in heterologous combinations. This observation was used to classify the investigated species by a 'position-frequency analysis' (PFA). After sorting the matrix of precipitate numbers in the ascertained optimal sequence of species, a cluster analysis was carried out. The phenogram showed 6 (respectively 8) group clusters. The members of the morphologic group I (Smith et al., 1952) was found only in group cluster 2. The phenogram was partly in agreement with phenograms based on other characteristics, e.g. DNA hybridization.

Represent the batches 2 of strain NCTC 3991 and NCTC 3992 B. coagulans?

In a previous publication (M. Hartung and E. Hellmann: Examination of 20 Bacillus Species by Crossed Immunoelectrophoresis under Taxonomic Aspects, Zbl. Bakt. Hyg. A 263 (1987) 509-524) we came to the conclusion that the species B. subtilis and B. coagulans were closely related. This statement has to be revised: The antigenic relationship is low. Further investigations have shown that all three B. coagulans-strains, although originating from different sources, were overgrown by B. subtilis. The same fact may have caused errors in other publications (e.g. Parry et al.: A Colour Atlas of Bacillus Species, Wolfe Medical Publications Ltd., London, 1983.

[Pulmonary fibrosis caused by hard-metal dusts]. / Lungenfibrosen durch Hartmetallstäube.

Hardmetals are broadly used in many different branches. In the FRG lung fibrosis caused by hardmetal-dust are recognized as occupational diseases (no. 4107). New findings concerning pathogenesis of this disease should be considered. Not only the dust of the presintered material is hazardous but also the inhalation of the sintered material. There is a special risk for tool-grinders. Cobalt is suspected to be the causal agent. In tool-grinders an elevated external and internal Cobalt-burden has been objectified. We report about 14 persons who suffered from lung fibrosis and worked in the hard metal industry. X-ray and pathohistological examinations may give some hints but there is no specific histological correlate. So the notifying procedure may be difficult. For this reason any case of aetiologically unknown lung fibrosis the lung biopsy and quantitative chemical analysis using AAS should be performed. In one patient the Cobalt-level in lung-tissue was significantly elevated. Toleration of invasive diagnostic measurements can not be demanded. Tool-grinders need more medical surveillance in future. As a preventive strategy the cobalt-exposure is to be reduced to a minimum. The external cobalt-burden at work-place can be estimated by the determination of the renal Cobalt-excretion.