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Biomedical subjects

W Peters

Publications and source records attributed to W Peters.

At least 271 records · Page 15Linked to original sources
PubMed1980

The chemotherapy of rodent malaria, XXXII. The influence of p-aminobenzoic acid on the transmission of Plasmodium yoelii and P. berghei by Anopheles stephensi.

More oocysts of Plasmodium yoelii developed in Anopheles stephensi if the mosquitoes received a supplement of p-aminobenzoic acid (PABA) in their diet prior to their taking an infective blood meal, than in unsupplemented control insects. The optimum concentration was 0.05% PABA in 10% sucrose. This effect was not observed if the blood meal was taken prior to feeding with PABA. Similarly, PABA administered to gametocyte-carrying mice increased the numbers of oocysts developing in mosquitoes fed on them subsequently, the effect also being dose dependent, and not mediated through an increase in gametocyte numbers. Sulphadoxine (which blocks PABA uptake) had the opposite action, reducing the numbers of oocysts either when fed directly to the mosquitoes or to the donor mice. These results are compared with those reported in other host-parasite systems by earlier workers, and certain paradoxical observations are discussed with reference to a possible relationship between sulphonamides and contaminating microorganisms in the vector mosquitoes.

4-Aminobenzoic Acid↗
PubMed1980

The experimental chemotherapy of leishmaniasis, VI. The development of rodent models for cutaneous infection with L. major and L. mexicana amazonensis.

Two models have been established of leishmanial infections in random-bred TFW albino mice, one with Leishmania major LV39 and the other with L. mexicana amazonensis LV38. These parasites produce consistent lesions when injected subcutaneously a short distance anterior to the base of the tail. Consistent infections could not be produced in the mice with other lines of the L. mexicana group of skin-dwelling protozoa, nor with a line of L. braziliensis guyanensis (LV475). The development of procedures for the maintenance of these parasites, the routine infection of mice and drug testing are described. L. major inocula consist of 1--5 X 10(6) promastigotes derived from NNN culture. L. m. amazonensis inocula contain approximately 10(7) amastigotes obtained from lesions in hamsters. The effects of drugs on the rodent lesions are assessed by two methods. Method A provides a simple lesion score from 0 to 3 made when lesions in control animals begin to reach maximum development (about six weeks after infection). Method B summates earlier 'mean lesion scores' to provide a graphic analysis of doses giving 50 and 90% lesion suppression at the end of seven weeks after the start of treatment which is for five consecutive days (SD 50 and SD90). The activities of several compounds used for the treatment of human leishmanial infections (organic antimonials, diamidines, amphotericin B and primaquine) are compared in mice infected with L. major LV39, L. m. amazonensis LV78 and 'L. infantum LV9' (the latter as reported earlier). It is concluded that the rodent models provide a good parallel with the response to these compounds in man. The visceral organism is significantly more responsive to Pentostam and Glucantime than are L. major or L. m. amazonensis. Primaquine is active only against 'L. infantum LV9'. All three parasites in mice respond to Berenil, but not to pentamidine which is used in the treatment of kala-azar. Amphotericin B is effective against cutaneous and visceral infections, but precautions must be taken to ensure its absorption by experimental animals.

Animals↗
PubMed1979

Basal bodies in the odontoblasts of the limpet, Patella coerulea L. (Gastropoda).

The odontoblasts in the long radular gland of Patella coerulea L. are arranged in a terminal position; therefore newly formed teeth already have an upright position. The long and slender odontoblasts have only one to three lengthy and ramifying apical microvilli. Between these pinnate microvilli a fine filamentous material appears which probably corresponds to chitin microfibrils. Therefore, the pattern of chitin microfibrils seems to depend on the arrangement of odontoblasts' microvilli. For the first time, basal bodies were found in the apical part of odontoblasts which led to the assumption that the radular gland originally might have been a mucous gland, the secretion of which was transported by cilia.

Animals↗
PubMed1979

Biochemistry of intraerythrocytic parasites III. Biochemical taxonomy of rodent Babesia.

Biochemical methods were investigated for use in taxonomic studies on Babesia. The techniques used were variation in the mobility of parasite enzymes on starch gels after electrophoresis and the measurement of the buoyant density of the DNA of the parasites. The study was carried out on four rodent species of Babesia (B. microti, B. rodhaini, B. hylomysci and B. muratovi) as well as two human isolates of Babesia believed to be of rodent origin. In addition a related piroplasm of rodents, Anthemosoma garnhami, was also investigated. The results indicate that biochemical methods would be of value in taxonomic studies on Babesia.

Animals↗
PubMed1979

Tissue PO2 during reanimation with hemoglobin solutions.

Solutions of conventional stoma-free hemoglobin (SFH) and of pyridoxylated stoma-free hemoglobin (SFH-PLP) were compared in a dog model of reanimation from severe arterial blood loss. SFH and SFH-PLP restored central hemodynamics after infusion without yielding significant differences between the experimental groups. To cope with the developing hypovolemia, Ringer's lactate load amounted to about 120 ml/kg, edema formation was not encountered. Skeletal muscle oxygenation was studied by means of a multiwire platin electrode. The infusion of SFH-PLP was associated with a shift to the right of the cumulative PO2-distribution curve, indicating better tissue oxygenation. Oxygen was not unloaded from SFH in plasma unless the oxygen extraction from red cell hemoglobin exceeded 40%. Oxygen unloading was, however, improved when SFH-PLP with low oxygen affinity was used. Thus, SFH-PLP merits further consideration as a short-term oxygen-carrying blood substitute.

Animals↗
PubMed1979

Electron microscopic studies on Blastocrithidia triatomae Cerisola et al. 1971 (Trypanosomatidae).

In the bug Triatoma infestans developmental stages of Blastocrithidia tritomae, which can be mistaken for T. cruzi during xenodiagnosis, were studied by means of electron microscopy. It turned out that three different forms appeared during the progressive divisions: "micro-", "pro-" and epimastigotes. The morphological study revealed significant criteria for a distinction from T. cruzi stages. Furthermore cyst-like bodies were observed often attached to the flagella of the different stages. As revealed by the presence of labyrinthine structures found in flagellated stages and in the cyst stages the latter were suggested as being specific cysts to be excreted with the feces and thus to establish new infections in other bugs. Apart from the cyst-like structures a comparison with the organelles known from other Trypanosomatidae showed only slight variations. A tubular cytopharynx-like structure, which was lined by microtubules, and the way of attachment of the flagellum to the surface of the host cell has not been described in Blastocrithidia before.

Animals↗
PubMed1979

[Prediction of the effects of client-centered psychotherapy on the basis of an indications interview].

Several effects of client-centered therapy were predicted on the basis of a short intake-interview divided into two parts: an exploration-phase and a quasi-therapy-phase. Elements of the international behavior and elements of the intrapersonal exploration of the client were rated by neutral observers and served as predictor variables as well as ratings of the experiences in the two interview situations by the client himself. Our population were 29 out-patients of a psychiatric clinic. We could demonstrate, that on the basis of an 45-minutes intake-interview it is possible to make a rather good prediction of the therapy outcome -- measured by several clinically relevant personality scales -- though therapists and interviewer were not identical and though there was a waiting period of several weeks between the interview and the start of therapy and though the therapists were rather unexperienced.

Communication↗
PubMed1978

Degradation of the radula in the snails Biomphalaria glabrata Say and Limnaea stagnalis L. (Gastropoda, Pulmonata).

The radula of snails is formed at the posterior end of the radular gland or pocket, and degraded at the same rate at its anterior end. Degradation is due to different secretory activities of the inferior epithelium of the radular gland. Its secretions seem to degrade enzymatically the matrix of the radular membrane and basal plates of teeth, leaving only chitin containing microfibres and degradation products. The sclerotized parts of the teeth remain unchanged, but as they are now only loosely connected with the radular membrane. they are torn off easily during feeding movements. The rest of the degraded and frayed radular membrane and the subradular membrane are also lost by abrasion during feeding. The cells of the inferior epithelium are connected with each other by septate desmosomes and an elaborate system of deep lateral interdigitation which may provide tensil strength. Extrusion of degraded cells of the inferior epithelium into the subradular membrane takes place, although the thick basal lamina forms a continuous sheath which is closely adjoined to the basal parts of the inferior epithelium. Nerve fibres containing vesicles with electron dense neurosecretory material (deduced from the diameter of 200--250 nm) are attached to this sheath or penetrate into it; they may be involved in the regulation of production and degradation processes during radula replacement. Problems of the forward transport of radula and inferior epithelium are discussed.

Animals↗
PubMed1978

Diminished sensitivity of re-initiation of translation to inhibition by cap analogues in reticulocyte lysates.

In a nuclease-treated reticuloyte lysate reinitiation of protein biosynthesis was less inhibited by 7-methylguanosine 5'-monophosphate (m7GMP), whereas primary-initiation could be totally blocked by cap analogues. We suggest that a cap binding factor binds to mRNA as a first step in initiation of protein synthesis and that this factor remains bound during the subsequent reinitiation cycles. Primarily because of the greater relative importance of the reinitiation process, globin synthesis in the untreated lysate was less inhibited by m7GMP.

Animals↗
PubMed1978

The chemotherapy of rodent malaria, XXIX DNA relationships within the subgenus Plasmodium (Vinckeia).

The relationships between rodent malarias were examined by means of DNA buoyant density determinations and DNA--DNA hybridization data. Current views of the existence in this group of four species: Plasmodium berghei, P. yoelli, P. vinckei and P. chabaudi were confirmed. The identity of two chloroquine-resistant lines derived from P. berghei N strain was established. One of these, the NS line, was found to be a subspecies of P. yoelii; the implications of this finding are discussed.

Animals↗
PubMed1978

The micro-ELISA technique in the serodiagnosis of visceral leishmaniasis.

The micro-scale Enzyme-linked Immunosorbent Assay (micro-ELISA) technique, with alkaline phosphatase as a marker enzyme, has been used for the serodiagnosis of human and canine visceral leishmaniasis, from foci in southern France. This technique which uses a soluble antigen is highly sensitive, with a degree of specificity slightly higher than that of the IFA. It is suggested that the micro-ELISA procedure can be added to the battery of serological techniques and would be particularly useful for large scale epidemiological studies of leishmaniasis.

Alkaline Phosphatase↗
PubMed1978

The biochemical and serological taxonomy of Leishmania from the Aethiopian zoogeographical region of Africa.

The electrophoretic variation of the enzymes MDH, GPI, G6PGH, 6PGDH were determined for 68 strains of Leishmania isolated in the Aethiopian zoogeographical region. Other characters determined were the DNA buoyant density of nuclear and kinetoplast DNA and the excreted factor serotype. The strains could be readily identified on the basis of these characters thus assisting in the elucidation of epidemiological problems. On the basis of these characters the strains could be divided into six groups. Three of the groups corresponded to L. donovani s.l., L. major and L. aethiopica. The three other groups identified at present have no specific name associated with them.

Africa↗