Mathematische Auswertung von Dichtegradienten zur Molekulargewichtsbestimmung von DNS mit Hilfe der EDV 1

Zusammenfassung Es wird ein EDV-Programm für den HP 9810 A zur rationellen Auswertung des Sedimentationsverhaltens von DNS im alkalischen Saccharosegradienten, insbesondere zur Berechnung wichtiger Kennzahlen für das Molekulargewicht und für die Bruchhäufigkeiten von DNS beschrieben. Voraussetzung dafür sind Radioaktivitätsprofile und Eichung des Gradienten mit Hilfe von Standard-DNS ausgehend von der Approximationsformel vonBurgi undHershey (1963).Im Programm hat der ExponentK den in unseren Eichläufen ermittelten Wert 0,353.Die Ausgabe der Daten und der Ergebnisse erfolgt als Ausdruck über eine rechnergesteuerte Schreibmaschine. Außerdem ist die graphische Wiedergabe über den rechnergesteuertenx- y-Schreiber vorgesehen. Der graphische Teil des Programms erlaubt es, die Versuchsvarianten (Gradienten) in quantitativer Relation mit unterschiedlicher Normierung auszuwerten, wie es speziell in Experimenten zur DNS-Reparatur notwendig ist.

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Computer program to analyse the molecular weight of DNA from sedimentation profiles

Summary A computer programm for the desk-top calculator HP 9810A to analyse sedimentation profiles and to calculate the weight average (Mw) and the number-average molecular weight (Mn) of DNA as well as of their breakage parameters (Nw andNn) is presented. The calculations are based on the radioactivity profiles of tritium-labelled DNA sedimented in alkaline sucrose gradients using a liquid scintillation spectrometer.With the aim of the approximation formula fromBurgi undHershey (1963) the exponentK has been estimated from the sedimentation of standard DNA with standard conditions and yields to 0.353.The data are printed out by mean of a computer-controlled typewriter or as a plot by mean of a computer-controlledX- Y plotter. The drawing program is adapted for different modes of standardisation. The most significant capabilities of the program are the estimation of the molecular weight and breakage number of any fraction or region of the sedimentation profile. In addition the graphic plot permits by use of different standardisation the estimation of quantitative changes under the experimental conditions.

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HP 9810A. (Mw, Mn Nw, Nn) () . , , , , — (1963). 0,353. . . , .

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Herrn Prof. Dr. Drs. h. c.Hans Stubbe zum 75. Geburtstag gewidmet.     

Intestinal cellular reaction of cattle after infection by Fasciola hepatica]

Defence reactions of cattle against Fasciola hepatica take place not only in the liver but also on a prehepatic level. The aim of the present experiments is to identify and quantify the cellular response in the small intestine. Five groups of two bulls (Simmental x Red Holstein, 6 months old) were infected by oesophageal probe with metacercariae of F. hepatica (MC) according to two experimental procedures. Two groups of bulls served as controls. In the first experiment both infected groups received 1000 MC once or twice at an interval of five weeks. The intestinal tissue was taken before infection and 5, 10 and 19 weeks p.i., respectively 5 and 14 weeks p. reinf. (p.ri.). In the second experiment, three infected groups received 400, 2 x 400 MC (at an interval of five weeks) and 800 MC respectively. Biopsies were taken one week ante infectionem, 6, 11 and 19 weeks p.i., respectively 1, 6 and 14 weeks post reinfectionem (p. ri.). The biopsies of the small intestine were prepared for histology and the tissue sections stained as follows: Astra blue for mucosal mast cells (MMC), Lendrum for eosinophils (EOS) and Periodic Acid Schiff (PAS) for goblet cells (GC). The density of the three cell populations in the mucosa was determined microscopically and quantified. In both experiments the density of the MMC and EOS increased with each reinfection and depended on the infectious dose. There was no significant variation of the GC-numbers. The described intestinal cellular reactions suggest a participation of the small intestinal wall in the immunity against the common liver fluke.     

Ecological basis of parasite control: Trematodes with special reference to fascioliasis

In this paper the main ecological components of selected animal trematode infection cycles are considered with regard to the possibilities of control. The geographical distributions of Fasciola hepatica, F. gigantica, Paramphistomum microbothrium, Schistosoma bovis and S. mattheei are compared in relation to the distribution patterns of their snail intermediate hosts. In order to constitute an effective lifecycle host, intermediate host and the eggs and freeliving stages of the parasite overlap in the effective biotope. Comparing the biotopes of the different trematodiases it becomes evident that they have much in common particularly as the snail intermediate hosts occupy identical niches in a food-chain in which the pollution by the host species results in abundant food for the snail. Moreover, the physical activaties of herbivores, e.g. trampling down the turf, create favourable habitats for the intermediate host.The dynamic nature of the freshwater snail habitats characteristic for trematodiasis, regularly results in a complete disappearance of the effective biotopes in the field. With regard to the parasite these effects are overcome by a long life-expectancy of egg producing parasites in the host population. Small scale changes in availability of appropriate hosts for successful cercarial establishment are compensated by the extended period of cercarial shedding from the snail population.These features in combination with the survival of eggs and the grazing and drinking behaviour characteristics of the hosts tend to stabilize the potential oscillations in transmission rate. Because of the complicated nature of interdependency within the host-trematode-intermediate host complex, the ecological base with regard to practical measures is fundamentally wide. However, the pressure upon the situation by social and economic conditions limits operative possibilities considerably.     

Embryo transfers from mares in athletic competition

The objective of this project was to produce multiple pregnant recipient mares during one year from each of four mares which were in athletic training and competition. Twenty-six embryos were recovered from the four mares in 38 collection attempts. Each embryo was surgically transferred to one of 20 recipient mares. Nine of 10 recipient mares which were transferred to on one occasion were detected pregnant at the one week post transfer pregnancy examination and six of eight mares which were transferred to on two occasions were detected pregnant at one of the one-week post transfer pregnancy examinations. Three of the 15 pregnant recipient mares lost their pregnancies by day 150. The 12 resulting pregnant recipient mares from the four competing donor mares demonstrated that donor mares can remain in athletic competition and at the same time provide viable embryos for embryo transfer.     

Modifiers of gastrointestinal motility of cattle.

Little clinically relevant, evidence-based data about the effect of motility modifiers on the GI tract of cattle are currently available. Additionally, some of the published results seem to be contradictory. Three main facts explain this apparent discrepancy: (1) Results may not be transferred from one species to another, because presence, concentration, location, distribution, and function of specific receptors may differ significantly among species. (2) The lack of a significant effect on smooth muscle preparations in vitro does not necessarily exclude a certain drug's motility-modifying property on affected animals in vivo. Certain drugs bind to receptors outside the myenteric plexus. Others, such as lidocaine and adrenergic-, dopaminergic-, and opioid-antagonists increase only GI motility, if inhibitory reflexes or a hyperactive state of the inhibitory sympathetic nervous system preexists. (3) Effects of motility modifiers as found in healthy experimental animals in vivo may not be similar to those found in spontaneously diseased animals. Accurate and reliable data on the effect of modifiers of GI motility of cattle will be obtained only from double-blinded, evidence-based, in vivo studies on spontaneously affected animals. Because well-documented results from such studies are extremely rare, intensive research in this field is warranted in the future.     

Immunizing efficacy of Toxoplasma gondii strains isolated from different hostsEfficacite d'immunisation par differentes souches de Toxoplasma gondii isolees de differents hotes

Studies were carried out to determine the fate of virulent Toxoplasma gondii challenge in immune animals. Toxoplasma strains isolated from human, swine, rabbit and cat hosts were used for the primary immunization of mice. Brains were removed at various intervals after the challenge and subinoculated into normal mice. Prior immunization with one of the nine toxoplasma strains enabled the mice either to eliminate or harbour the challenge organisms without loss of virulence. The outcome of challenge infection was dependent on the parasite strain used for the immunization and the time interval between challenge and subinoculation. Mice immunized with strain KSU isolated from a cat eliminated repeatedly administered challenge from 80% of animals. Strain S 162 isolated from a swine eliminated similar challenge from only 20% of animals. The results indicate that the extent of protection against virulent T. gondii can vary widely and is related to the immunogenicity of the original immunizing strain.     

Pathological Lesions in Swine at Slaughter: I. Baconers

An extended disease recording programme in pigs has been carried out by the meat inspection service at Sentralslakteriet, Forus, Stavanger. A data system including 57 disease codes has been applied. In the period 1975–1977 an average of 85,000 baconers were slaughtered yearly. About 39 % of these were given disease remarks; 42–47 % of the lesions were directly related to the parasites Sarcoptes scabiei (rind lesions) and Ascaris suum (white spots in the livers). The thoracic cavity was the most commonly affected part of the body with 30–35 % of all recorded lesions.Sixteen disease codes occurred at frequencies above 0.3 %, and they encompassed approx. 97 % of all recorded lesions. Scabies occurred at an average of 12 % of the fatteners. Parasitic hepatitis of severe and moderate degrees were seen in about 11 %, pleurisy in 7 %, pneumonia — severe and moderate — in 5.4 %, pericarditis in 4.3 %, pyaemia and abscess/-es in 2.5 %, tail lesions in 2.3 %, perihepatitis and other non-parasitic liver lesions in 2.2 %, polyarthritis and arthritis in 1.7 %, tuberculous lesions in the cervical lymph nodes in 0.9 %, peritonitis in 0.9 % and atrophic rhinitis — external lesions — in 0.8 % of the carcasses. The majority of the other 41 disease codes occurred at frequencies below 0.1 %.A seasonal variation was pronounced in scabies, numerous white spots in the liver, and tuberculous lesions in the cervical lymph nodes. It could be noted in pleurisy, pericarditis, perihepatitis and other non-parasitic liver lesions, arthritis and atrophic rhinitis, but not in pneumonias, moderate number of white spots in the liver, tail lesions, pyaemia, abscess/-es, peritonitis and polyarthritis.     

Evaluation of trypanosomiasis control alternatives using an epidemiologic simulation model

The effect of various disease-vector control alternatives on the prevalence of trypanosomiasis in southwest Ethiopia was examined with the aid of an epidemiologic model. The alternatives considered included vegetation clearing by manual labor, game elimination, insecticidal spraying from airplanes coupled with settlement, use of sterile male Glossina, avoidance of tsetse infested areas, increasing the resistance of the cattle population, therapy, and combinations of the above methods. First, the currently estimated endemic prevalence of trypanosomiasis (27.3%) in the simulated area of Ethiopia was established and maintained over a 10 year period. Then, various control alternatives were introduced and the simulation was run for an additional 10 years to observe the effect of these control alternatives on the prevalence. The combined use of vegetation clearing, insecticides, therapy, and settlement (or resettlement) was the most effective and feasible method of trypanosomiasis control for the simulated situation.     

Infectious salmon anaemia (ISA) epidemiology in Norway

A case-control study is reported of 57 holdings (holdings in which salmon are raised in sea-water) with infectious salmon anaemia (ISA) and 61 holdings without ISA, together with a follow-up study of the control holdings, during 1988–1990. Generally the identified risk factors implied poor biosecurity since passive transmission (proximity to other ISA holdings) and active transmission (management practices which increased exposure to foreign biological material) were found to be major risk factors. The findings indicated that ISA was spread by infected live salmon or infected biological material i.e. animal waste or discharge from normal operations and slaughter. The findings also indicated that decreased host resistance could be important, but these results could be also be explained by a misclassification bias. Moreover, the findings indicate that a prompt eradication policy and improved biosecurity would be important means of controlling ISA.