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Biomedical subjects

M Kühne

Publications and source records attributed to M Kühne.

At least 19 recordsLinked to original sources
PubMed2007

Evaluation of a serological method for the detection of Taenia saginata cysticercosis using serum and meat juice samples.

Two peptides, HP6-2 and Ts45S-10, were used as antigens for the detection of antibodies against Taenia saginata cysticercosis in serum and meat juice samples using enzyme-linked immunosorbent assay (ELISA). Positive control samples were obtained from animals experimentally infected (serum) and from animals naturally infected (meat juice). The two peptides and a pooled preparation of both peptides were evaluated, and their cut-off points with both sample categories were calculated. ELISA results from these different peptides were compared. Sensitivity and specificity of HP6-2 using serum were calculated as being 100 and 98%, respectively, showing to be higher than the values for the other antigens used. The average optical density (OD) value for negative samples was 0.646, whereas it was 1.702 for the positive control samples. This peptide was used to examine serum samples from animals with cysts and random field serum samples. For meat juice samples the pooled peptides showed the highest sensitivity and specificity, as they were 100 and 95%, respectively. The average OD values for the negative and the positive reference meat juice samples were 0.379 and 1.291, respectively. The optimal dilution of the meat juice samples for the ELISA was very low, as it was 1:20 using the pooled peptides, compared with 1:800 serum dilution using HP6-2. To the authors' knowledge, this is the first report of a successful testing for T. saginata cysticercosis using meat juice.

Animals↗
PubMed2006

Visual diagnosis of Taenia saginata cysticercosis during meat inspection: is it unequivocal?

A total of 267 cysts were collected from March to December 2004 from two main abattoirs in northern Germany. The cysts were classified by the usual organoleptic methods during meat inspection as Cysticercus bovis. The reported prevalence of cysticercosis in the abattoirs was 0.48 and 1.08%, respectively. The cysts were examined macroscopically for description of their morphology and constituents and classified as viable or degenerating (dead). The DNA was extracted from these cysts and subjected to polymerase chain reaction (PCR) for evaluation of the detection methods used and to make certain that the cysts did indeed belong to C. bovis, as indicated at the slaughterhouses. Two sets of primers were used with different sensitivity levels. The first, HDP1, was able to detect 200 fg of Taenia saginata DNA and 100 pg of C. bovis DNA. The other primer set, HDP2, was able to detect 1 pg of T. saginata DNA and 1 ng of C. bovis DNA. No more than 52.4% of the samples tested positive for C. bovis in the PCR using both primers, while 20% of the viable cysts and 49.2% of the degenerating cysts tested negative with both primers.

Abattoirs↗
PubMed2006

[Future role of the official veterinarian at the ante- and post-mortem inspection].

The new European food hygiene legislation which will apply from 1 January 2006 on brings massive changes in the implementation of the ante- and post-mortem in-spection about. Key element in this new regulation is the introduction of a risk-based inspection of graduated intensity which in particular cases may be reduced to a document check and a visual inspection. Important changes also concern responsibility assignment between official veterinarian and official auxiliary in inspection tasks. Furthermore, the official veterinarian is assigned additional responsibility (animal welfare, animal health check). Regarding the extended competence of the official auxiliaries through the new regulation, food industry is requiring a diminution of the inspection costs. In this article, the future scope of duties of the official veterinarian at the ante- and post-mortem inspection is presented, as well as the practical consequences the implementation of the new meat hygiene regulation will have.

Animals↗
PubMed2005

Effects of aging prior to freezing on poultry meat tenderness.

The objective of this study was to investigate the effects of aging prior to deboning and deep-freezing on the tenderness of cooked broiler breast fillets. Broilers (Ross-208) that were 37 and 38 d old were slaughtered in a licensed poultry meat plant. After spray chilling, carcasses with BW between 1,080 and 1,300 g were selected for the study and transported to a chilling room (2 to 4 degrees C). The whole carcasses were aged for up to 24 h. During the aging process, continuous measurements were made of pH values, electric conductivity, and firmness of the raw fillets. After the aging process, the carcasses were deboned, and the breast fillets were immediately frozen to an internal temperature of -20 degrees C. Tenderness was measured both mechanically with a Warner-Bratzler shear force device and by sensory testing. The ultimate pH values in the fillets were reached during the first 5 h of aging. Electric conductivity increased during the whole aging period. During the first hours of aging, firmness increased significantly, corresponding with the onset of rigor mortis. After between 8 and 9 h of aging, firmness decreased significantly. Shear force values of aged fillets also changed significantly; the highest values were found at the beginning of aging, which then decreased from the sixth hour. The results of the instrumental tenderness measurements were confirmed by the sensory evaluations. Implementation of in-plant measurements of firmness, thus, seemed to be useful in predicting the sensory quality of poultry meat.

Animals↗
PubMed2005

Shortening of the bovine tongue according to regulation (EC) 999/2001 is not complying with the current legal definition of specified risk material - a macroscopical and histological preliminary study.

The full elimination of all specified risk material (SRM) in food of animal origin is crucial for consumer protection and is of high priority in inner EU trade. Among other tissues, the tonsils of cattle are considered as SRM. The aim of this study was to evaluate whether the 'cut at the back of the tongue just before the tongue bones' required by EC regulation is sufficient to remove tonsils and lymphatic tissue completely. Eight skulls from cattle were collected for the simulation of a vertical cut according to the EC regulation and the detection of the target at the back of the tongue. Further, specimens of the lingual mucosa were cut out from two tongues and examined microscopically. The most caudal of these specimens was from the macroscopically visible part of the lingual tonsil. The most rostral specimen contained the most caudal Papilla vallata. Simulation of the obligatory ventro-dorsal cut yielded hits at varying locations on the dorsal surface of the tongue, sometimes including tissue of the lingual tonsil. Histological examination of the lingual mucosa gave clear evidence that lymphatic tissue resembling the tissue of a tonsil in terms of its histological organization and infiltration of the mucosal epithelium could even be found in areas with no macroscopically visible lingual tonsils.

Abattoirs↗
PubMed2005

[Do we need pathogen-free livestock for food safety?].

The reduction of the entry of pathogens in the food chain is an important premise in improving the safety of food of animal origin. Since food animals are the main reservoir for pathogens, the prevalence of pathogens in livestock is of great importance. Unfortunately, classical measures to improve animal health can not exclude the presence of the main food-borne zoonotic agents (Salmonella, Campylobacter, Listeria monocytogenes, verotoxinogene Escherichia coli, Toxoplasma gondii) in "clinically healthy" animals. Absence of pathogens in livestock must be regarded as an unrealistic aim. To achieve an effective improval of product safety through logistical, hygienic or technological measures both farmers and food producers need valid data about the prevalence of pathogens in livestock, in each animal and in raw material of animal origin, respectively. Yet available data are insufficient. New European directives and regulations concerning monitoring and control of zoonosis demand the systematic control of presence of zoonotic agents in livestock and later steps of the food chain.

Animal Diseases↗
PubMed2004

[Parasites in meat: a challenge for veterinarians in meat hygiene].

Meat hygiene is an important instrument of preventive public health since the end of the nineteenth century. The methods used during ante-mortem and post-mortem inspection are partly quite traditional. This is in particular true for the identification of parasites in meat. The aim of this review was to present facts on aetiology, prevalence and importance of meat-borne parasitic hazards. The capacity and the limits of the ante-mortem and post-mortem inspection for the identification of parasitic hazards are considered. Further, suggestions for the improvement of the meat hygiene are given. Cysticercosis, Toxoplasmosis and Sarcocystosis are exposed in detail. With regard to Cysticercosis, the integration of serological methods in the inspection procedure could result in a tenfold improvement of diagnostical sensitivity. With regard to Toxoplasmosis, it is obvious that meat containing Toxoplasma-cysts may reach the consumer, as animals infected with Toxoplasma gondii can neither be recognised in the ante-mortem inspection nor in the meat inspection. Systematical serological investigations on farm level would allow an appropriate judgement during meat inspection and minimize the consumer exposure to this parasite. Further, reliable methods for the detection of Toxoplasma-cysts have to be developed. With regard to Sarcocystosis, the compulsory inspection of the muscle surfaces to recognise a "massive infection with Sarcocystis" is very doubtful in its interpretation. There is a need for suitable microscopic, serological and molecular biological methods for the detection of Sarcocystis-species and reliable informations on the seroprevalence of the parasite in slaughtering animals.

Animals↗
PubMed2002

Physical and biological parameters affecting DNA double strand break misrejoining in mammalian cells.

In an attempt to investigate the effect of radiation quality, dose and specific repair pathways on correct and erroneous rejoining of DNA double strand breaks (DSBs), an assay was applied that allows the identification and quantification of incorrectly rejoined DSB ends produced by ionising radiation. While substantial misrejoining occurs in mammalian cells after high acute irradiation doses, decreasing misrejoining frequencies were observed in dose fractionation experiments with X rays. In line with this finding, continuous irradiation with gamma rays at low dose rate leads to no detectable misrejoining. This indicates that the probability for a DSB to be misrejoined decreases drastically when DSBs are separated in time and space. The same dose fractionation approach was applied to determine DSB misrejoining after alpha particle exposure. In contrast to the results with X rays, there was no significant decrease in DSB misrejoining with increasing fractionation. This suggests that DSB misrejoining after alpha irradiation is not significantly affected by a separation of particle tracks. To identify the enzymatic pathways that are involved in DSB misrejoining, cell lines deficient in non-homologous end-joining (NHEJ) were examined. After high X ray doses, DSB misrejoining is considerably reduced in NHEJ mutants. Low dose rate experiments show elevated DSB misrejoining in NHEJ mutants compared with wild-type cells. The authors propose that NHEJ serves as an efficient pathway for rejoining correct break ends in situations of separated breaks but generates genomic rearrangements if DSBs are close in time and space.

Alpha Particles↗
PubMed2001

Radiation-induced genomic rearrangements formed by nonhomologous end-joining of DNA double-strand breaks.

Two major pathways for repairing DNA double-strand breaks (DSBs) have been identified in mammalian cells, nonhomologous end-joining (NHEJ) and homologous recombination (HR). Inactivation of NHEJ is known to lead to an elevated level of spontaneous and radiation-induced chromosomal rearrangements associated with an increased risk of tumorigenesis. This has raised the idea of a caretaker role for NHEJ. It is, however, not known whether NHEJ itself can also cause rearrangements. To investigate, on the DNA level, the influence of a defect in NHEJ on the formation of genomic rearrangements, we applied an assay based on Southern hybridization that allows the identification and quantification of incorrectly rejoined DSB ends produced by ionizing radiation. After 80 Gy of X-irradiation at a high dose rate (23 Gy/min), wild-type cells repaired 50% of the induced DSBs within 24 h by incorrect rejoining. This frequency of DSB misrejoining is considerably reduced in NHEJ-deficient cells. Low-dose-rate experiments, in which the cells were exposed to 80 Gy over a period of 14 days under repair conditions, led to no detectable misrejoining in wild-type cells but revealed a misrejoining frequency of 10% in NHEJ-deficient cells. This shows that in situations of separated breaks, NHEJ deficiency leads to genomic rearrangements, in agreement with chromosomal studies. However, if multiple DSBs coincide, even wild-type cells form genomic rearrangements frequently. These repair events are absent in Ku80-, DNA-PKcs-, and DNA ligase IV-deficient cells but are present in RAD54(-/-) cells. This strongly suggests that NHEJ has, in addition to its caretaker role, also the potential to effect genomic rearrangements. We propose that it serves as an efficient pathway for rejoining correct break ends in situations of separated breaks but generates genomic rearrangements if DSBs are close in time and space.

Animals↗
PubMed2001

Tetracycline residues in meat and bone meals. Part 2: the effect of heat treatments on bound tetracycline residues.

The stability of bound tetracycline residues during heat treatments at 133 degrees C and 100 degrees C for up to 45 min was investigated. An intermediate product from a rendering plant was mixed with bone splinters that contained bound tetracycline (TC) and chlortetracycline (CTC) residues. The mixture was heated in an autoclave at 133 degrees C for 20, 30 and 45 min and at 100 degrees C for 20 and 30 min and subsequently dried at 103 degrees C for 4 h. Two different extraction procedures with hydrochloric acid were used, one with and one without the previous sedimentation of bone particles. Tetracycline concentrations were determined by HPLC analysis before and after the heat treatment. A complete destruction of tetracyclines during heat treatment at 133 degrees C could not be demonstrated, but there was a significant decrease of TC by about 50%. CTC was less resistant to the same temperature, which brought about a reduction of 90-100%. Treatment at 100 degrees C did not bring about any reduction, except for CTC after extraction without sedimentation. The possible toxicological relevance of the findings is discussed. Further research has to be done on possible degradation products of the tetracycline derivatives.

Animals↗
PubMed2001

Tetracycline residues in meat and bone meals. Part 1: methodology and examination of field samples.

The incidence of tetracycline residues in commercially available samples of meat meals and meat and bone meals was investigated. Four different methods were used on each of the 87 samples from nine different rendering plants in Germany: examination using a screening fluorescence test; examination by high performance liquid chromatography analysis using three different extraction procedures (succinate buffer, hydrochloric acid, hydrochloric acid after sedimentation of bone particles). Tetracyclines were found in 100% of the samples by one or more of the extraction procedures. The highest concentrations found in meat meals were 2048 microgkg(-1), 1393 microgkg(-1) and 608 microgkg(-1) for oxytetracycline, tetracycline and chlortetracycline, respectively. In meat and bone meals the highest concentrations were 2295 microg oxytetracycline kg(-1) 848 microg tetracycline kg(-1) and 1274 microg chlortetracycline kg(-1). The extraction after sedimentation was the most effective of the applied extraction procedures and exposed the highest total tetracycline concentrations. The results of this investigation showed that considerable amounts of tetracyclines have to be expected in field samples. Further research has to be done on the heat stability of bound tetracycline residues.

Animal Feed↗
PubMed2000

Stability of tetracycline in water and liquid manure.

The objective of this study was to establish a suitable model for the prediction of the environmental stability of antibiotics in water and liquid manure. The model consists of incubation systems for solutions with installations for stirring ventilation. It was used to examine the stability of tetracycline in ventilated and unventilated Ringer's solution and liquid pig manure for a period of 8 days. Tetracycline concentrations decreased significantly during the experiment. The fastest degradation was observed in ventilated liquid manure. The test might be used as a screening test for the determination of the degradation half-life of antibiotics in the first phase of an environmental safety study according to directive 92/18/EEC.

Animals↗
PubMed2000

No dose-dependence of DNA double-strand break misrejoining following alpha-particle irradiation.

PURPOSE: To investigate whether an explanation for the high effectiveness of densely ionizing radiation with regard to complex biological endpoints can be derived from measurements of radiation-induced double-strand break (DSB) misrejoining. MATERIALS AND METHODS: Misrejoining of radiation-induced DSB in normal human fibroblasts was determined by comparing hybridization analysis of large restriction fragments as a measure for correct rejoining, with results from a conventional pulsed-field gel electrophoresis technique (FAR) that measures total DSB rejoining. In order to investigate DSB misrejoining at doses for which chromosome aberration data are available, a dose fractionation protocol was applied so that the number of DSB at any given timepoint was low but the cumulative amount of misrejoined DSB sufficient for detection and precise quantitation. RESULTS AND CONCLUSION: After an acute 80Gy alpha-particle exposure and a repair incubation period of 24 h, 50% of all initially induced DSB were misrejoined, in agreement with data obtained for X-rays. X-irrradiation with 16 x 5 Gy, 8 x 10 Gy, 4 x 20 Gy, or 2 x 40 Gy and repair incubation of 24 h following each individual dose fraction was recently reported to yield misrejoining frequencies that strongly decrease with increasing fractionation (Löbrich et al. 2000; Genes, Chromosomes and Cancer, 27, 59-68). In the present study, constant misrejoining frequencies of 50% were observed after alpha-particle exposure with the same fractionation protocol. This difference between alpha-particles and X-rays is in accordance with the high biological effectiveness of densely ionizing radiation and provides a direct link between misrejoining of DSB and cytologically visible exchange aberrations. Further evidence suggests that if the same dose range is compared, the number of misrejoined DSB exceeds the number of microscopically visible aberrations by an order of magnitude for both radiation types, probably reflecting the high resolution of the hybridization approach compared with cytological techniques.

Alpha Particles↗
PubMed2000

Joining of correct and incorrect DNA double-strand break ends in normal human and ataxia telangiectasia fibroblasts.

Chromosomal aberrations are believed to result from the incorrect joining of DNA double-strand breaks (DSBs). In an attempt to investigate induction and rejoining quality of DSBs following ionizing radiation exposure in specific genomic locations of mammalian DNA, an experimental approach based on Southern hybridization of single-copy probes to NotI restriction fragments was developed. Induction of DSBs is measured from the decrease of the band intensity representing the unbroken restriction fragment. An increase in intensity of the hybridization band following repair incubation determines reconstitution of the original restriction fragment and thus rejoining of correct DNA ends. We investigated the dose dependence of DSB misrejoining using X-ray doses of 5, 10, 20, 40, and 80 Gy and provide evidence that the number of misrejoined DSBs exceeds, for the same doses used, the number of cytogenetically visible aberrations by an order of magnitude, reflecting the higher resolution of our assay. Induction of DSBs and joining of correct and incorrect break ends were further investigated in cells from a patient with the cancer-prone disease ataxia telangiectasia (AT) and in heterozygous AT cells. We found, compared to normal cells, identical induction rates and identical kinetics for joining correct ends following an 80-Gy X-ray exposure. After 5 and 10 Gy, however, AT homozygotes showed a 50% elevation in the proportion of breaks that are not correctly rejoined. These data indicate a defect in the accuracy of DSB rejoining in AT cells that may account for radiation sensitivity and the occurrence of the high level of chromosomal aberrations observed in AT cells. Genes Chromosomes Cancer 27:59-68, 2000.

Ataxia Telangiectasia↗
PubMed1998

Assignment of linkage groups to pea chromosomes after karyotyping and gene mapping by fluorescent in situ hybridization.

Chromosomes of the pea (Pisum sativum L.) were submitted to fluorescent in situ hybridization (FISH) with probes specific for the oligonucleotides (AG)12, (AC)12, (GAA)10, and (GATA)7 and for the genes encoding 25S rRNA, 5S rRNA and the storage proteins legumin A, K and vicilin. A fourth 5S rRNA gene locus, apparently specific for an accession of the cultivar Grüne Victoria, was newly detected. This allowed all seven chromosome pairs to be distinguished by FISH signals of rRNA genes. The same was possible using a combination of oligonucleotide probes or of oligonucleotides and rRNA gene-specific probes in multicolour FISH. Rehybridization with the 5S rRNA gene-specific probe allowed us to assign vicilin genes to the short arm of chromosome 5, the single legumin A locus to the long arm of chromosome 3 and the legumin B-type genes (exemplified by legumin K) to one locus on the short arm of chromosome 6. Correlation of these data with an updated version of the pea genetic map allowed the assignment of most linkage groups to defined chromosomes. It only remains to be established which of linkage groups IV and VII corresponds to the satellited chromosomes 4 or 7, respectively.

Chromosome Mapping↗