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Biomedical subjects

R Gothe

Publications and source records attributed to R Gothe.

At least 37 records · Page 2Linked to original sources
PubMed2000

'Babesia gibsoni' of dogs from North America and Asia belong to different species.

18S rDNA sequences from 4 isolates of Babesia gibsoni originating from Japan, Malaysia and Sri Lanka were compared with a previously published, 0.5 kb portion of the 18S rDNA from a B. gibsoni isolate from California, USA, and with the corresponding 18S rDNA sequences of other Babesia spp. Distance, parsimony and maximum likelihood analyses showed almost identical genotypes among the small canine Babesia from Asia, but an unexpectedly distant genetic relationship to that from the USA. While the American isolate segregated together with B. equi, the Asian isolates showed a close relationship to B. divergens and B. odocoilei. These results indicate that small Babesia of dogs originating from North America and Asia belong to different, genetically distantly related species.

Animals↗
PubMed2000

Modus operandi of oviposition in Dermacentor reticulatus (Acari: Ixodidae).

The process of oviposition in D. reticulatus was observed and found to be a sequence of exactly coordinated, interlocking events independent of the phase of oviposition. The average period of oviposition in the investigated ticks was 31.6 days at 20 degrees C and 95% relative humidity. The number of eggs deposited on each day increased until reaching a maximum on the fifth day of oviposition and then decreased continuously. As a result, most of the eggs were deposited during the initial phase of oviposition. The total number of eggs was proportional to the ticks' weight replenishment. Egg-laying commenced with the lowering of the capitulum and the simultaneous spread of the pedipalps which were lowered to the body wall embracing the genital aperture on both sides. Immediately afterwards the cuticular sac of Gene's organ was pushed out and retracted several times. At the cuticular sac's maximum extension, the vestibulum vaginae prolapsed, forming the ovipositor as an extended tube which handed over an egg to the two horns of the cuticular sac after a brief, but intensive, contact with the cuticular sac. Then the vestibulum vaginae invaginated, the pedipalps closed, and the cuticular sac was retracted. Finally, the egg was transported onto the dorsal area of the tick by means of a vigorous rising of the capitulum. During the course of oviposition most of the events, especially the period of egg embracement by the cuticular sac, were prolonged, as was the total time for laying one egg. Similarly, the intervals between successive egg-laying processes increased continuously. The number of eggs deposited was not dependent on the functional ability of Gene's organ, as shown by similar numbers of deposited eggs from ticks with and without mechanical blocking of the cuticular sac. But the participation of the organ in the process of oviposition proved to be a prerequisite for the viability of the eggs. Larvae developed and hatched only from those eggs which were deposited from ticks with an undisturbed Gene's organ. In comparison, eggs without contact to the cuticular sac of Gene's organ dried up and shrivelled immediately after being deposited and did not hatch. Consequently, it strongly suggests, together with the results from other studies, that Gene's organ covers the eggs with a secretion that prevents the loss of water.

Animals↗
PubMed2000

Species of the genus Psoroptes (Acari: Psoroptidae): a taxonomic consideration.

The biosystematic status of mite species belonging to the genus Psoroptes Gervais, 1841 is difficult to determine by phenotypic methods and has been subject to taxonomic revisions and ongoing debate. At present, the existence of five species, P cuniculi (Delafond, 1859), P. ovis (Hering, 1838). P. equi (Hering, 1838), P. cervinus Ward, 1915 and P. natalensis Hirst, 1919, is generally accepted. This classification is based mainly on the host species, the localization of the mites on their hosts and morphological characters of male mites. However, a critical review of the literature indicates that the features used to discriminate between the five species are not unequivocal: (a) the localization of mite populations on host animals is not completely strict, (b) the lengths of the outer opisthosomal setae of male mites, which are the main morphological features used for species discrimination, overlap between the five postulated species, and (c) host specificity cannot be deduced from results of transfer experiments. Rather, conspecificity of the members of the genus Psoroptes has to be presumed which is supported by molecular genetic analyses. On these grounds and on rules of priority P. cervinus Ward, 1915, P. cuniculi (Delafond, 1859), P. natalensis Hirst, 1919 and P. ovis (Hering, 1838) are seen as synonyms of P. equi (Hering, 1838).

Animals↗
PubMed2000

The mechanism of oviposition in Argas (Persicargas) walkerae (Acari: Argasidae).

The process of oviposition in A. walkerae was observed and found to be a sequence of exactly coordinated, interlocking events independent of the age of ticks. Egg-laying always commenced with numerous dorso-ventral movements of the capitulum. The pedipalps were spread during the last dorso-ventral movement and lowered to the ventral body wall embracing the genital aperture on both sides. Simultaneously, the cuticular sac of Gene's organ emerged and immediately everted maximally. Immediately afterwards the vestibulum vaginae prolapsed from the genital aperture touching the cuticular sac. The vestibulum vaginae handed over an egg to the cuticular sac after a brief contact. Then the vestibulum vaginae invaginated, the pedipalps closed and the cuticular sac was retracted. Finally, the capitulum very frequently moved up and down and the free egg was pushed in front of the ticks. The total time of laying an egg averaged 27 min in both 4-week-old and 12-month-old ticks. In 4-week and 12-month-old ticks, egg-laying was preceded by a mean preoviposition period of 6.1 days and 7.5 days, respectively, while the mean oviposition was completed in 14 and 10 days and the average egg totals were 119 and 103.

Animals↗
PubMed2000

Detection and micro-scale isolation of a low molecular mass paralysis toxin from the tick, Argas (Persicargas) walkerae.

This study describes the isolation of a 11 kDa paralysis toxin from crude larval extracts of Argas (Persicargas) walkerae by exploiting the cross-reactivity of a monoclonal antibody (4B12), directed against the paralysis toxin of Rhipicephalus evertsi evertsi. This low molecular mass is in contrast to previous findings of a 60-70 kDa toxin for A. (P.) walkerae, but is similar to neurotoxins isolated from venomous forms of the class Arachnida, which comprise the orders Araneae (spiders). Scorpionida (Scorpions) and Acari (ticks and mites). Since numerous antigenic bands, ranging between 11 and 115 kDa, were detected by the monoclonal antibody 4B12, the possibility of toxin-complex formation and the effect of pH on the latter were investigated by means of HPLC and ammonium sulphate precipitation. The results suggest that physiological conditions, with respect to pH and ionic strength, promote the formation of heterogeneous toxin-complexes while an acidic pH favours the formation of a more homogeneous toxin-containing complex. Furthermore, the effect of partially purified toxin on neurotransmitter release from crude rat brain synaptosomes was investigated, since tick paralysis toxins are hypothesised to inhibit neurotransmitter release from the presynaptic terminal. Both calcium-dependent, as well as calcium-independent release was inhibited by the toxin-containing sample.

Animals↗
PubMed2000

Close genotypic relationship between Enterocytozoon bieneusi from humans and pigs and first detection in cattle.

The reservoirs and the routes of transmission of Enterocytozoon bieneusi are still unknown. In humans, it is the most commonly found microsporidial species. It has also been found repeatedly in pigs, too. The first detection of E. bieneusi in cattle is reported herein. Two distinct genotypes were characterized and compared with 4 other genotypes from humans, 6 from pigs, and 1 from a cat. From these 13 E. bieneusi genotypes known to date, 25 polymorphic sites could be identified in the internal transcribed spacer of the rRNA gene. The spectrum of polymorphisms within and between each of the 4 host species indicates a close relationship between E. bieneusi strains from humans and pigs, whereas those from cattle are more distantly related. The data suggest the absence of a transmission barrier between pigs and humans for this pathogen.

Animals↗
PubMed1999

Molecular analyses suggest monospecificity of the genus Sarcoptes (Acari: Sarcoptidae).

To clarify the taxonomic status of mites of the genus Sarcoptes, the second internal transcribed spacer (ITS-2) of the rRNA gene, as well as phenotypic characters, were investigated in 23 isolates from nine host species in four continents. Phenotypic differences among isolates were observed, but the range of variation within each isolate precluded the differentiation of individual mites. Genotypically, there was no delimitation between distinct genotypic groups and no correlation with host species or geographic origin was evident. These results support the conspecificity of the mites investigated and confirm the view that the genus Sarcoptes consists of a single, heterogenous species.

Animals↗
PubMed1999

Genetic differentiation of mites of the genus Chorioptes (Acari: Psoroptidae).

In an effort to clarify the species status of mites of the genus Chorioptes the second internal transcribed spacer of the rRNA gene was characterized in 14 isolates from cattle, horse, sheep and llama of different geographic origins. The genotypes segregated into two clearly separated groups of DNA sequences. In addition, two phenotypes could be distinguished by the lengths of the outer opisthosomal setae of male adults which had previously been designated as Chorioptes bovis and Chorioptes texanus. The bipartite division of genotypes and phenotypes correlated completely in all isolates. Nine out of ten cattle isolates from three continents were determined to be C. texanus including the first description in Europe and Northern America. Chorioptes texanus appears to have a wider geographic distribution than previously known. Chorioptes bovis was found in four different host species. The apparent lack of host specificity of both species implicates a potential that mites are dispersed freely in a wide range of hosts and this might have contributed to the wide geographic distribution of these species.

Acari↗
PubMed1998

Characteristic genotypes discriminate between Babesia canis isolates of differing vector specificity and pathogenicity to dogs.

The first and second internal transcribed spacers (ITS1, ITS2) as well as the intervening 5.8S coding region of the rRNA gene were characterized in eight Babesia canis isolates of differing geographic origin, vector specificity, and pathogenicity to dogs. The genotypes determined by sequencing segregated into three clearly separated groups close to or near the species level and correspond to the previously proposed subspecies B. canis canis, B. canis vogeli, and B. canis rossi. The three genotypes can be distinguished by Sau96I digestion of the polymerase chain reaction (PCR)-amplified rDNA target.

Animals↗
PubMed1998

Genetic evidence suggests that Psoroptes isolates of different phenotypes, hosts and geographic origins are conspecific.

The second internal transcribed spacer of the rRNA gene was characterised in 15 Psoroptes isolates collected from the ears or bodies of rabbits, goats, sheep and cattle originating from four continents. Morphologically, the isolates were differentiated as Psoroptes cuniculi, Psoroptes ovis and Psoroptes cervinus. Genotypically, the isolates were highly homogeneous, except for the existence of different rDNA classes. In view of previous phenotypic data, a possible conspecificity of these species is proposed.

Animals↗
PubMed1998

[Imported arthropod-borne parasites and parasitic arthropods in dogs. Species spectrum and epidemiologic analysis of the cases diagnosed in 1995/96].

Between January 1995 and December 1996 nonendemic or only regionally occurring arthropodborne parasites including ehrlichiae and parasitic arthropods in Germany were detected in 484 dogs, whereby at least 15 species were involved. Listed in decreasing order, Leishmania infections occurred most frequently, followed by infections/infestations with Babesia canis, Ehrlichia canis, Rhipicephalus sanguineus, Dirofilaria immitis and Dermacentor reticulatus. The other species, namely Babesia gibsoni, Trypanosoma congolense, Hepatozoon canis, Ehrlichia platys, Dirofilaria repens, Dipetalonema reconditum, Dermacentor marginatus, Boophilus microplus and Cordylobia anthropophaga were demonstrated in a few or single dogs. Irrespective of the pathogen-species, most of the dogs had travelled with their owners to Mediterranean countries or to Portugal or had been imported from there. Infections with B. canis were diagnosed very frequently in dogs returning from Hungary. Of the 28 dogs with previous residence in Germany only, twelve and four animals were infected with B. canis and E. canis, respectively, and seven and five dogs were infested with R. sanguineus and D. marginatus, respectively.

Animals↗
PubMed1998

[Migration and transposition of Oesophagostomum quadrispinulatum larvae from feces].

Investigations on the migration and translation of free-living stages of Oesophagostomum quadrispinulatum, using faeces containing eggs as starting material, revealed that mostly third stage larvae and very few second stage larvae migrated out of faeces, whereas first stage larvae remained in the faeces. The emigration rates depended on ambient relative humidity. Compared with the control, third stage larvae emigrated out of faeces at rates of 0.3%, 1.6% and 12.2% at 50%, 75% and 100% relative humidity, respectively. Offering helminth-free faeces, emigrated third stage larvae returned into faces at rates of 0.4-1.2%, 5.8-17.7%, 39.0-52.7%, and 45.2-60.7% after 1 h, 24 h, 5 days and 14 days, respectively. After a period of 1, 2, 3 or 4 weeks staying out of faeces, emigrated third stage larvae returned into faeces at rates of 23.3%, 8.8%, 22.1% and 6.0%, respectively. An examination of the horizontal translation revealed that most of the third stage larvae migrated distances up to 80 cm and a few even up to 150 cm returning into helminth-free faeces.

Animals↗
PubMed1998

[Dog tourism and import: an inquiry in Germany on the extent as well as on the spectrum and preference of countries of residence and origin respectively].

A survey was conducted among practicing veterinarians and at pet clinics in Germany in order to estimate the extent of tourism with dogs and import of dogs and to determine the range and preference of the foreign countries involved. The survey covered the years from 1985 to 1995 and included 5240 dogs, of which 4567 (87.2%) were born in Germany and 673 (12.8%) were born abroad. Among the latter, 263 (39.1%) originated from Mediterranean countries and Portugal, 344 (51.1%) were born in other European countries and 66 (9.8%) were from non-European countries. Of all 5240 dogs surveyed, 2894 (55.2%) had been taken abroad at least once between 1985 and 1995. Of these, 2424 (53.1%) were born in Germany, 470 (69.8%) were born abroad. Of the 2894 dogs taken abroad, 1929 (66.7%) travelled to Mediterranean countries or Portugal and 1152 of these had additional travels to other countries as well. The spectrum of all countries travelled to was very broad, but numerous dogs were taken regularly, repeatedly and exclusively to Austria, Switzerland, Italy, Spain or France. Other countries were visited only once for the majority of dogs. The analysis of the annual survey data revealed a steady increase of dogs along on trips from Germany to other countries, rising from 31.1% in 1990 to 40.8% in 1994. In any of these years, always more than 56% of these dogs were taken to Mediterranean countries.

Africa↗
PubMed1998

[Ehrlichia canis infections of dogs in Germany. Epidemiology, diagnosis, therapy and prophylaxis].

Between January and December 1997 infections with Ehrlichia canis were detected in 211 dogs in Germany. Of the 53 epidemiologically evaluable dogs, 19 animals born and raised in Germany had travelled with their owners abroad in endemic areas, 30 dogs originated from there and four dogs had never left Germany. As regards to the possible location of infection it has been registered that most dogs had been taken to countries of the Mediterranean Sea (Spain, France, Italy, Greece) or had been imported from there. On inquiry, ticks had been forwarded from four dogs only, which were determined as Rhipicephalus sanguineus. The subsequent serological investigation of these four dogs revealed a Rickettsia conorii infection in two of them.

Animals↗
PubMed1997

Morphology of the eyes in adult Hyalomma truncatum ticks (Acari: Ixodidae).

The eyes of Hyalomma truncatum ticks are morphologically similar in both sexes. They appear as paired hemispherical structures situated dorsally between the first and second pair of legs on the lateral scutal margin. Each eye consists of a lens and photoreceptor cells, which are separated by a fine fibrillar layer and the hypodermis. The lens contains numerous channels which open beneath the epicuticle, converge uninterruptedly to the interior of the lens and end below the fine fibrillar layer. The inner closure of the lens is formed as an oval plateau with a cone-like projection situated caudolaterally and eccentrically to the longitudinal axis of the lens. The hypodermis is a single layer of cells, situated immediately below the fine fibrillar layer. Beneath the hypodermis, directly below the cone-like projection of the inner lens are the photoreceptor cells localized in a rosette-like arrangement. Facing the hypodermis, each photoreceptor cell is provided with numerous microvilli. The microvilli consistently border the microvilli regions of other cells at different angles but are always oriented at a right angle to the lenticular channels. The photoreceptor cells are unipolar neurons, whose axons arise from the basal portion of the cell and join to nerve fibre bundles forming the optic nerve. It is concluded that the eyes in adult H. truncatum ticks possess all the structures necessary to perceive and conduct light stimuli and visual signals.

Animals↗
PubMed1997

Relationships between species of the Rhipicephalus sanguineus group: a molecular approach.

The biosystematic status of species belonging to the Rhipicephalus sanguineus group is difficult to determine by phenotypic methods and has been subject to frequent revisions and ongoing debate. Yet, the differentiation of species within this complex is of clinical importance especially in veterinary medicine due to different host specificities of the transmitted pathogens. In order to generate quantifiable and comparable data independent of environmental influences, a section of the second internal transcribed spacer (ITS2) of the rRNA gene was sequenced for 6 species belonging to the Rhipicephalus sanguineus complex: Rhipicephalus sanguineus sensu stricto, R. turanicus, R. rossicus, R. pumilio, R. pusillus, and R. camicasi. Rhipicephalus sanguineus s. str. and R. turanicus as well as R. pumilio and R. rossicus were found to have a close genetic relationship compatible with possible conspecificities. Conversely, R. pusillus was found to have the most distant relationship to the other species.

Animals↗
PubMed1997

[Leishmaniasis in dogs in Germany: epidemiological case analysis and alternatives to conventional causal therapy].

Between January 1993 and September 1995 Leishmania infections were detected in 236 dogs in Germany. Of the 132 epidemiologically evaluable dogs, 35 animals had travelled with their owners abroad in endemic areas and 97 dogs had been brought from these regions to Germany by animal lovers. As regards to the possible location of infection it has been registered that these dogs have been taken to countries of the Mediterranean Sea (Spain, France, Italy, Turkey) or to Portugal or had been imported from there. Therapeutic trials with allopurinol revealed that this drug administered at daily doses of 20 mg/kg bodyweight p.o. over weeks disposes of a sufficient therapeutic efficacy against canine leishmaniosis.

Allopurinol↗