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Biomedical subjects

H Schulz-Key

Publications and source records attributed to H Schulz-Key.

At least 73 records · Page 4Linked to original sources
PubMed1984

Observations on adult Onchocerca volvulus maintained in vitro.

Adult Onchocerca volvulus were enzymatically isolated with collagenase from excised nodules and kept in TC medium 199 with Hank's salts supplemented with various sera. Male and female worms survived in the culture medium and 10% human serum on average for about 11 days (maximum 28 days) and 14.5 days (maximum 42 days). Up to 4,000 microfilariae were expelled by each female per day, but the production of new oocytes or development of embryos could not be observed in vitro.

Animals↗
PubMed1984

Studies on nodules and adult Onchocerca volvulus during a nodulectomy trial in hyperendemic villages in Liberia and Upper Volta. II. Comparison of the macrofilaria population in adult nodule carriers.

In the Liberian rain-forest and the savanna of Upper Volta 189 adult nodule carriers were operated on. From 2231 extirpated nodules 3327 male and 5713 female macrofilariae were isolated. About 98% of the male worms and 88% of the female worms were found alive. The sex ratio of the live male and female worms was 1:1.5 in Liberia and 1:1.6 in Upper Volta. Less than 1% of all live macrofilariae were immature in both countries. 22% of the live male worms in Liberia were regarded as old. The percentage of old male and female worms in Upper Volta and that of the old female worms in Liberia were similar (5-7%). The portion of old worms was independent of the age of the patients in Liberia. Dead worms were found in 66% of the Liberians and in 85% of the Voltaics. The percentage of patients with dead worms increased with the age. About 0.5% of all male and 8% of all female worms were calcified. In Liberia the percentage of calcified worms increased with the age of the patients. In both countries the highest number of live and dead worms were found on the pelvic girdle. On the thorax many more macrofilariae were found in Upper Volta than in Liberia. This may contribute to the severe eye lesions in this savanna area. The presented findings provide some basic information for the planning and performance of trials with macrofilaricidal drugs in hyperendemic areas of West Africa. However, the striking differences between individual worm burdens have to be considered.

Adolescent↗
PubMed1981

The transmission of Onchocerca tarsicola (Filarioidea: Onchocercidae) by Odagmia ornata and Prosimulium nigripes (Diptera: Simuliidae).

Onchocerca tarsicola is a subcutaneous filariid of the red deer living on the tendons of the radial-carpal and tibial-tarsal joints. Its microfilariae concentrate mainly in the external ears. The extrinsic cycle of this parasite was investigated. In a hyperendemic area wild-caught Odagmia ornata were dissected, as well as samples which had fed on a tame deer and been kept in the laboratory after the infecting blood-meal. About 3 to 5% of the flies were infected with larval stages of Onchocerca tarsicola. More than 40% of Odagmia ornata induced to feed on the ears of the deer became infected and about 30% of the flies which survived more than 18 days contained third-stage larvae. The larval development in the vector is described. Prosimulium nigripes appears to be a second natural vector of Onchocerca tarsicola. Observations concerning the potential vectors of O. flexuosa, O. tubingensis and Cutifilaria wenki living in red deer are discussed.

Animals↗
PubMed1980

Investigations on female Onchocerca volvulus for the evaluation of drug trials.

Females of O. volvulus show several typical morphological alterations during their ontogenesis. In order not to attribute such natural findings to the efficacy of drugs in drug trials female worms isolated from untreated patients in Liberia and Togo were examined by light microscopy. Local incrustations could be found regularly on the surface of the female parasite. Different inclusions are described which could often be found. They partially lead to degeneration and calcification. For the evaluation of ovocidal or embryocidal efficacy of drugs the developmental stages of 290 untreated female worms were quantitatively assessed, normal and pathologically altered forms were distinguished. Embryos were obviously not produced continuously but in intervalls of unknown length and frequency. Two third of the females contained embryos and microfilariae, one third showed eggs only or had empty uteri. The number of the developmental stages per female varied considerably. On the average more than 200,000 stages per female were found.

Animals↗
PubMed1980

Onchocerca volvulus: effect of suramin on lactate dehydrogenase and malate dehydrogenase.

Lactate dehydrogenase and malate dehydrogenases were partially purified and characterized from adult O. volvulus. The molecular weight of lactate dehydrogenase was determined to be 130 000, those of malate dehydrogenase I and II to be 120 000 and 65 000, respectively. The activities of both malate dehydrogenases and of the lactate dehydrogenase were strongly inhibited by suramin. The inhibition constants were determined to be in the range of 2 microM to 5 microM. The type of inhibition was found to be competitive with respect to the coenzyme NADH and to be non-competitive to the substrates. It is suggested that the mode of action of suramin in the therapy of Onchocerciasis might depend on the blokkade of reoxidation of NADH produced within the glycolytic pathway.

Animals↗
PubMed1980

Analysis of enzymatically isolated adults of Onchocerca volvulus after treatment of patients with suramin or metrifonate.

The application of a new technique is described permitting a better recognition of activities of drugs on macrofilariae of Onchocerca volvulus. In two villages of a hyperendemic focus in Liberia onchocercomata were excised from untreated persons and from patients treated with conventional doses of suramin or metrifonate. The adult worms were enzymatically isolated with collagenase and microscopically examined for degenerative alterations including calcifications and for the presence of eggs and embryos in the female parasites. Six weeks after the last dose of suramin the degenerative alterations could not be distinguished qualitatively from those in untreated worms, but a statistically significant macrofilaricidal efficacy could be shown by quantitative analyses, although more than half of the parasites were still alive at this early date. Metrifonate did not show any macrofilaricidal effect.

Animals↗
PubMed1978

A simple technique to assess the total number of Onchocerca volvulus microfilariae in skin snips.

A technique for the assessment of the total number of microfilariae in skin snips from onchocerciasis patients is described. For the digestion of the skin tissue the biopsies are incubated at room temperature for 24 hours in medium 199, containing 3 mg/ml collagenase and antibiotics. This process leaves the microfilariae unharmed. A comparative study of the emergence of the microfilariae in different media showed that only 20% of the total number were released after 30 minutes in distilled water. After 24 hours incubation in isotonic saline 80% were found.

Humans↗
PubMed1978

Acid phosphatase activity in the larval stages of Onchocerca volvulus developing in the vector Simulium damnosum.

The staining patterns of acid phosphatase activity of the various larval stages of Onchocerca volvulus from experimentally infected Simulium damnosum s.l. have been described. The enzyme activity was localized in the anal vesicle/pore area of the first-stage larva, in the anal vesicle and intestine of the secong-stage larva and all over the body in the third-stage larva. Early third-stage larvae could be differentiated from late third-stage infective larvae by the presence of pronounced enzyme activity in the rectum area of the former. There were no detectable differences in the staining patterns between the forest and Sudan-savanna strains of O. volvulus developing in S. damnosum.

Acid Phosphatase↗
PubMed1977

Isolation of living adult Onchocerca volvulus from nodules.

A technique for the isolation of adult Onchocerca volvulus from excised onchocercomata is described. The nodules are incubated in medium 199 containing 1-5 mg collagenase and 0.2 mg gentamicin per ml for 6-48 hours in a waterbath at 30-37 degrees C. A proportion of the worms can be isolated alive.

Animals↗
PubMed1977

Worm burden of onchocerca volvulus in a hyperendemic village of the rain-forest in West Africa.

During a study on the effects of nodulectomy on onchocerciasis in a village in the Liberian rain-forest 400 Onchocerca-nodules were excised from 34 inhabitants. The analysis of the nodules revealed a worm burden of 718 complete live male and 1062 complete live female worms as well as 9 male and 117 female worms which were mostly calcified and degenerating. 73% of the live females contained developing embryos or released microfilariae, the other females either contained eggs or showed empty uteri. Some observations were made on degenerating worms. The male:female sex ratio was 1:1.5 and possible reasons for this are discussed.

Adolescent↗
PubMed1977

On the development of onchocerca volvulus in mosquitoes.

In an attmept to find an experimental vector for Onchocerca volvulus which can be easily be bred under laboratory conditions, the susceptibility of Anopheles gambiae and Aedes aegypti to infection with O. volvulus was studied. The mosquitoes were fed on a membrane feeding apparatus containing microfilariae of O. volvulus. Whereas A. gambiae was refractory to infection. 14.9% of A. aegypti females became infected with developing stages, 11,2% showed young and mature third-stage larvae as well as some which had developed abnormally. However, no infective larvae of O. volvulus were found in the abdomen or the head of the mosquitoes.

Aedes↗
PubMed1976

[Investigations on the Filariidae of the Cervidae in Southern Germany. 4. Onchocerca garmsi Bain and Schulz-Key, 1976, a subcutaneous Filaria of red deer (Cervus elaphus)].

O. garmsi is a filaria living free in the subcutaneous tissues on the chest of red deer. The microfilarial distribution pattern in the skin of the host is studied. The convergent distribution of microfilariae of O. garmsi, O. tubingensis and O. cervicalis on the one hand and of O. tarsicola and W. rugosicauda on the other hand is discussed.

Animals↗
PubMed1975

[Investigations on the filariidae of the cervidae in Southern Germany. 1. Development of the nodule, finding of the sexes and production of the microfilariae in Onchocerca flexuosa (Wedl, 1856), in the red deer (Cervus elaphus) (author's transl)].

The biology of O. flexuosa was studied during the examination of numerous subcutaneous nodules, which were taken from the hides of red deer of all age-classes. In fawns the development of the nodule is induced by the immature stages, probably by the females. At the same time a hematome is formed. Males of different ages penetrate into the nodule where mature or immature females are present. Later they mate and remain within the nodule until the microfilariae in the uteri of the females develop. Usually 1 or 2, occasionally 4 females are found together. During the development of the embryos in the uteri the initially stretched female winds up. Only a short anterior part remains always straight. It is put out through the wall of the capsule in order to release the microfilariae. The males are often the majority reaching to 13 in one nodule. During the release of the microfilariae the males are found outside the nodule on the surface or near-by in the subcutaneous connective tissue. Both sexes are able to mate a second time. In older deer the males are also able to induce the development of nodules.

Aging↗
PubMed1975

[Studies on the Filariidae of Cervidae in southern Germany. 2. Filariidae of the red deer (Cervus elaphus)].

In southern Germany many of the red deer are infected with 4 filariid species. The microfilariae of 3 subcutaneous and one intradermal filariae are described. Skin snips were taken according to a regular pattern from the hides of several killed deer. The emerging microfilariae were identified and counted, and the characteristic distribution of each species in the skin was plotted. The adult worms of O. tarsicola are located on the abductor tendons of the tibiotarsal or radiocarpal joints. Some microfilariae are found in the tissues near the adults, but they concentrate at a considerable distance away, in the skin which covers the outer parts of the ears and the nose. The adult worms of O. tubingensis are found in subcutaneous nodules on the caudal part of the back. The microfilariae are distributed on the ventral part of the body with maximum densities in the region of the sternum and with lower densities on the inner sides of the hindlegs. O. flexuosa is also found in nodules on the back and flanks of the deer, while the microfilariae are distributed on the posterior part of the body with maximum densities on the inner sides of the hindlegs. C. wenki lives intradermally on the dorsal part of the trunk. The microfilariae are found in the skin near the adults. The infection rates of 94 red deer investigated during 1907-1974 were high: O. tarsicola 82%, O. tubingensis 23%, O. flexuosa 96%, C. wenki 85%. The prepatent period of all species is no longer than 6 months.

Age Factors↗