Experimental infection of Nematospiroides dubius in Swiss albino mice. VII. Worm burdens and serum protein fractions

The paper deals with the alterations in serum protein profiles and its possible correlation with the worm burden in Swiss white mice infected with single and repeated doses of N. dubius infective larvae. Marked changes observed in serum protein fractions in all the groups were found to be further raised with increase in dose levels. However, maximum (optimal) changes of different fractions depend on the total number of larvae inoculated irrespective of the number of inoculations given. Percentage of worm retention was found to be inversely proportional to the number of larvae inoculated. Worm expulsion during repeated infections was attributed to the therefore, participation of increased amount of immunoglobulins and, humoral immunity (immediate type) has been suggested to play a major role in the immune mechanism of this model.     

Split-dose recovery for radiation-induced tumours in rat skin.

Tumour-related recovery in rat skin was estimated from the dependence of tumour yield on time between split doses of electron radiation. Tumour yield versus dose was established at nine dose points, and at three points the dose was split into two equal fractions spaced 0-25, 3-2 or 6-3 hours apart. After irradiation the rats were observed periodically for at least 64 weeks, and at death the tumours were examined histologically. The dependence of yield on dose for single doses was consistent with a quadratic function up to a peak yield at about 1600 rad. The effect of split doses on tumour yield depended on the position on the dose--response curve. At the lowest split dose, the yield declined with a half-time of about 1-8 hours. At the intermediate split dose, an initial increase was followed by a decline with a half-time of about 3-9 hours. At the highest split dose, the tumour yield increased with time between exposures. Fractionation-induced increases in tumour yield were explained as a sparing effect on cell lethality, whereas tumour-related recovery per se was indicated at the lower two doses.     

Nematospiroides dubius: passive transfer of protective immunity to mice with monoclonal antibodies

Nine hybridoma cell lines secreting monoclonal antibodies specific for Nematospiroides dubius were produced by fusion of the mouse myeloma cell line NS-1 to either spleen cells or mesenteric lymph node cells from mice repeatedly infected with N. dubius. Seven of the antibodies were identified as IgM and two as IgG1. Each monoclonal antibody bound to polypeptide epitopes on both infective larvae (L3) and adult worms. However, five antibodies bound preferentially to L3 and three to adult worms. All nine antibodies reacted with high molecular weight protein antigens. Passive protective immunity in Balb/c mice was demonstrated with monoclonal antibodies Nd2 and Nd3 in ascites fluid which stunted both male and female worms and reduced parasite fecundity.     

Alternative pathway activation of complement by a murine parasitic nematode (Nematospiroides dubius)

The cuticular surface of the infectious third-stage larvae of Nematospiroides dubius activates complement via the alternative pathway. Sensitisation of larvae with complement or with antibodies from the serum of immune mice (resistant to reinfection) promoted the adherence of mouse peritoneal exudate cells to the larval cuticle during incubation in vitro. The infectivity of larvae sensitized with antibody or complement was significantly reduced after incubation with cells from immune mice.     

Biochemical manifestations of the poisoning of larvae of Aedes aegypti (Insecta, Diptera) by the delta-endotoxin of Bacillus thuringiensis israelensis. I. Hemolymph carbohydrates

The glycemia of 4th instar larvae of Aedes aegypti (Diptera Culicidae) was determined over a 30 min to 36 hrs period following their immersion in water containing 0.00-0.01-0.02-0.1-1.0 mg per liter of a 12,000 I. U. per mg preparation of the delta-endotoxin of Bacillus thuringiensis israelensis. Seven major carbohydrate fractions were separated in the haemolymph, among which glycogen, trehalose and glucose were identified; the most concentrated of the 4 remaining unknown fractions, exhibits a similar chromatographic behavior but different chemical properties than glucuronic acid. The glycogen fraction shows two large amplitude peaks at 1 hr 30 and 6 hrs with 0.1 mg/l, whereas with the 2 lower doses (0.01 and 0.02 mg/l) a first drop from 30 min to 1 hr is followed by a peaking at 12 hrs. The haemolymph trehalose concentrations of intoxicated larvae increase relatively to controls 2 hrs after incubation with the lower dose; by contrast, they decrease with the 2 higher doses. The glucosemia increases in all cases, but more markedly with the higher dose as soon as 1 hr following the treatment. A positive correlation was found over the whole treatment duration between the glucosemia nd the trehalosemia of control larvae. The regression slope of this relationship decreases with increasing toxin doses and turns to negative values with 0.1 and 1.0 mg/l. These observations suggest the hypothesis that a uncontrolled increase of trehalase activity develops according to the increasing stages of intoxication. This clearly differenciates the effects of the B. T. i toxin from those of parasites, such as Fungi, Sporozoans or Nematodes in Mosquitoes.     

Comparative evaluation of conjugate vaccines in the Haemophilus influenzae infection model

We used a murine model of Haemophilus influenzae type b (Hib) infection to analyze the immunologic response to two commercially available PRP conjugate vaccines (HbOC, PRP-T). The mortality rate in mice infected with a large dose of the bacteria after vaccination with HbOC or PRP-T at two and three doses was significantly lower than in non-vaccinated mice and mice vaccinated by one dose. Furthermore, for infections caused by a small bacterial dose, the mortality rate in mice vaccinated with one, two, or three doses was significantly lower than in non-vaccinated mice. The induction level of anti-PRP antibodies, especially IgG, in serum of mice vaccinated by two or three doses was higher than in those vaccinated with a single dose. Our results indicate that the dose of vaccine influences its efficacy in protecting against Hib infection. Our results also showed a lack of difference between two different PRP conjugate vaccines.     

Impairment of primary expulsion of Trichuris muris in mice concurrently infected with Nematospiroides dubius

Primary immune expulsion of Trichuris muris was markedly delayed by concurrent infection with Nematospiroides dubius. Maximum delay of expulsion was dependent on size and timing of N. dubius infection relative to T. muris infection. In NIH mice infection with 400 N. dubius larvae immediately before or after T. muris infection was found to be most effective in suppressing expulsion. Infection on day 8 of T. muris infection, when mice are sensitized to T. muris, also impaired expulsion. From this evidence it is suggested that the larvae of N. dubius are immunosuppressive and that the efferent role of the immune response to T. muris is inhibited. The results are discussed in terms of non-specific immunosuppression and their relevance to the tropical disease situation is emphasized.     

Regulation of toxocariasis in mice selectively reared for high and low immune responses to Nematospiroides dubius

Test mice have been selectively reared for high (H) or low (L) immune responses to Nematospiroides dubius. After secondary infection with N. dubius, the L mice voided ten times as many eggs in their faeces as the H mice, and at necropsy, 71% versus 20% of the inoculum of N. dubius were recovered as adult worms from the L and H mice respectively. Furthermore, N. dubius were more fecund in the L than in H mice. High or low immune responsiveness was not restricted to N. dubius infection in these mice but was also observed during Toxocara canis infection. The migration of T. canis larvae from gut via the liver to skeletal muscle and CNS was inhibited in H versus L mice. Many more larvae were recovered from the livers of H compared with L mice which was indicative of greater immunity in the H mice. The protective immune response in H compared with L mice to both N. dubius and T. canis included pronounced eosinophilia and elevated antiparasite antibody titres.     

Trichinella spiralis: expression of rapid expulsion in rats exposed to an abbreviated enteral infection.

Rats infected with Trichinella spiralis for the first week of the enteral infectious cycle displayed a strong rapid expulsion reaction during a challenge infection. The response was induced with equal facility in animals given low or high immunizing doses of infectious larvae (500 to 5000 larvae). Large challenge infections resulted in a 10–15% reduction in the efficiency of rejection as assessed 24 hr after challenge. Rats became primed to express rapid expulsion within the first week of primary infection whether the infection remained patent or not. However, maximum effectiveness was not realized until the second week after the initial infection. Once induced, the capacity to express rapid expulsion persisted for 6 weeks after the primary infection. Immunized hosts were capable of resisting two challenge infections spaced by periods of from 12 to 72 hr. This finding suggests that a mediator is not consumed by the initial response.     

Nematospiroides dubius: susceptibility to infection and the development of resistance in hypothymic (nude) BALB/c mice.

BALB/c-nu/nu mice and their intact nu/+ littermates are equally susceptible to infection with third-stage larvae of Nematospiroides dubius. Unlike their heterozygous littermates, however, the nu/nu mice are unable to form ganulomata in the intestinal wall and become only partially resistant to rechallenge. Following two or more infections, nu/nu mice maintain a high burden of adult intestinal worms, whereas worms are lost from immune nu/+ mice. Studies in T cell-injected nu/nu mice suggest that a full complement of T cells is needed to develop maximum resistance against the infective third-stage larvae and to expel adult worms. Measurement of serum immunoglobulin levels indicate that infected nu/+ mice have very high levels of IgG1 whereas the levels of IgG2a are reduced. In infected T cell-injected nu/nu mice, IgG1 levels increase with the number of T cells injected, whereas IgG2a levels are variable but always higher than in infected nu/+ mice.     

Dose-independent effect of misonidazole in fractionated irradiations of hypoxic Vicia faba bean roots

The radiosensitization of 5 mM misonidazole (Miso) was measured in Vicia faba bean roots with regimens of single, three, six and twelve fractions of 250 kVp X-rays. To inhibit cell division, the beans were kept at a constant temperature of 3.5 degrees C during irradiation and between fractions that were spaced 24 hours apart. The doses in various regimens were graded such that they ranged between 27 and 350, and 42 and 513 cGy per fraction in Miso-treated and non-treated regimens, respectively, under hypoxia. The sensitivity enhancement ratio (s.e.r.) was constant throughout the dose range employed with an average value of 1.62. The s.e.r. increased to 2.3 when measured with single doses at 19 degrees C. It is concluded that the s.e.r. is dose-independent and that temperature enhances the effectiveness of the drug.     

Trichinella spiralis: quantitative relationships between intestinal worm burden, worm rejection, and the measurement of intestinal immunity in inbred mice

The effect of widely different doses of Trichinella spiralis muscle larvae on time to rejection of intestinal adults and on host survival was assessed in mice of the three rejection phenotypes; strong, intermediate, and weak. Rejection is weak with doses of less than 50 larvae per mouse. At these doses all mice rejected worms at a similar rate and no phenotypic variation was evident among strains. In contrast, rejection time was shortest for all strains and phenotypic variation among strains was evident in the range 50-100 muscle larvae/mouse. Above this dose the time taken to rejection increases monotonically with dose for all mouse strains examined. Despite this, the relative strength of rejection (i.e., phenotype) of a given strain of mouse was not changed at higher doses. Based on an end point of 98% rejection of the infective dose, time to rejection was predictable to +/- 1 day for all mouse strains and doses tested over the range 100-1000 worms administered. The principal reason for the increased time to complete rejection with larger worm doses was a delay in the initiation of intestinal rejection. This delay was evident above a dose of 50-100 larvae per mouse and occurred in all strains. Once begun, rejection was faster and eliminated more worms in unit time at higher doses (400-800 more) than at lower doses of worms. This appeared to be due to a stronger immune response of the host at higher doses. However, the increase in the rate of rejection was still not as great as the increase in the dose. We postulate that the delay in rejection with increased dose is due to a requirement for a "critical mass" of effectors/worm required to cause rejection. As dose increases, more time is required to reach the level at which worm rejection commences. Deaths due to higher doses of worms also occurred in a strain-specific manner and were temporally biphasic. The intestinal phase of infection produced mortality from 1 to 5 days after infection and the strongest rejection phenotype (NFS) was also the most resistant to intestinal deaths. Deaths occurring after Day 5 were due to the parenterally migrating newborn larvae. The weakest rejection phenotype, that of the B10 congenics, was also the least resistant to intestinal deaths. An experimental formula describing 98% worm rejection time with different doses was derived from the data.(ABSTRACT TRUNCATED AT 400 WORDS)     

Nematospiroides dubius: response of the late fourth-stage larva to anthelmintics in vitro

Approximately 60% of fourth-stage larvae of Nematospiroides dubius recovered from mice 6 days after infection, developed to the young adult stage when cultured over a 7-day period in a complex medium in vitro. Larvae at the late fourth stage of development were found to be highly susceptible to most broad spectrum anthelmintics under in vitro conditions, the benzimidazole, imidazothiazole, pyrimidine, isothiocyanate and macrocyclic lactone compounds all being active at very low concentrations. Narrow spectrum anthelmintics active only against ascarids, pinworms, filariae, cestodes or trematodes had little or no effect on these larvae. Ineffective also were those chlorinated hydrocarbon, substituted phenol and salicylanilide compounds known to affect Haemonchus but not trichostrongylid worms in general. It is concluded that in vitro assays employing larvae of N. dubius are useful for the stringent screening of compounds for broad spectrum antitrichostrongyle activity. Used in conjunction with in vivo screens employing N. dubius in mice, they also afford means for detecting intrinsic activity against the parasite in a system free from any complicating host pharmacokinetics.     

Resistance to ivermectin by Haemonchus contortus in goats and calves.

Efficacy of ivermectin on susceptible or resistant populations of the parasitic nematode Haemonchus contortus was determined in cattle and goats held in a barn. Goats were each infected with 3000 infective, ivermectin-susceptible or -resistant H. contortus larvae on day 0 and reinfected with 2000 infective larvae on day 24. Goats were treated orally with 600 micrograms kg-1 ivermectin on day 31. No significant differences were detected in blood packed cell volume (PCV) or total protein (TP), prepatent period, or epg among the four groups of goats that were each infected with one of four parasite strains (one susceptible, three resistant). There were no differences among the four parasite strains in the numbers of infective larvae that developed to the third larval stage from fecal cultures or in the viability of cultured infective larvae when held in the laboratory at 27 +/- 1 degrees C for 14 weeks. After treatment with ivermectin, there were significant differences among the parasite strains in PCV, TP, and epg. Total worm counts were reduced by 94 to 97% with three times the recommended dose. Immature and adult Skrjabinema ovis were also present in two treated goats. In a second test, one goat infected once with 10,000 infective larvae of a resistant strain of H. contortus and then treated with nine doses of ivermectin, increasing from 500 to 2000 micrograms kg-1 over a period of 133 days, had 35 adult worms at necropsy. In a third test, three calves were readily infected with an ivermectin-resistant strain of H. contortus from goats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of different dietary levels of fish protein hydrolysates on growth, digestive enzymes, gut microbiota, and resistance to Vibrio anguillarum in European sea bass (Dicentrarchus labrax) larvae

Two fish protein hydrolysates (FPH) were incorporated into four diets prepared for start-feeding sea bass larvae, at two different levels (10% and 19% of total ingredients): a commercial FPH, CPSP, in which the molecular mass of the main fraction of soluble peptides (51%) was between 500-2500 Da, and an experimental FPH obtained by acidic silage of sardine offal, SH, with a main portion of soluble peptides (54%) ranging from 200 to 500 Da. The diet with 10% of the commercial FPH gave the best results in terms of growth, survival and intestinal development, as evaluated by the early activity of digestive enzymes in the brush border membrane (alkaline phosphatase and aminopeptidase N). This was related to the low level of Vibrio spp. counted in the larvae of group C10. The high dose of FPH, especially in the experimental preparation rich in short peptides, seemed to favour the dominance of Vibrio sp. TYH3, which behaved opportunistically. The effect of the experimental FPH was ambiguous, since early larvae challenged with Vibrio anguillarum were more resistant to the pathogen, especially at high FPH dose (group S19). This might be due either to direct antagonism between V. anguillarum and Vibrio sp. TYH3, or to the stimulation of the immune response in the larvae. These results indicate that different molecular weight fractions and concentrations of feed-soluble peptides may affect the growth performance and immunological status of sea bass larvae. Consequently, a low dose of commercial FPH seems advisable, both for larval development and for the bacterial environment, although further research is required to determine and characterize peptide fractions that may have a beneficial effect on growth and immune response, and to determine their optimal inclusion levels in diets for sea bass larvae.     

The relationship between o.e.r., r.b.e. and number of fractions for X-ray- or neutron-induced skin damage.

The skin reactions in aerated and hypoxic mouse tails after single or fractionated doses of 250 kV X-rays or fast neutrons (6 MeV deuterons on beryllium) have been measured. The o.e.r. for one to sixteen fractions of X-rays remains constant, while that for one to ten fractions of neutrons decreases with increasing neutron fractionation and decreasing neutron dose/fraction. The o.e.r. for X-rays was 1.7, for single-neutron doses 1.4, and for ten fractions of neutrons 1.25. It was anticipated that the o.e.r. for neutron-induced damage would decrease further as neutron fractionation is increased because the contribution to damage from the highest LET components of dose, the alpha and heavy recoil particles, would increase relative to the lowe LET components. The r.b.e. values obtained for skin damage were higher at all neutron doses/fraction examined in this study on tails than all those previously obtained in studies on skin at other sites on four species. This may be due to the influence of hypoxia on the r.b.e. measurements in the mouse tail.     

The induction by X-rays of chromosome aberrations in male Guinea-pigs and golden hamsters. IV. Dose response for spermatogonia treated with fractionated doses.

The effect of dose fractionation on the induction of translocations by 400 and 600 rad X-rays in spermatogonia of guinea-pigs and hamsters was investigated cytologically. Three types of fractionation were used, dividing the dose into (a) two equal fractions 24 h apart, (b) two equal fractions 8 weeks apart, and (c) eight or twelve equal fractions of 50 rad, at intervals of one week. The two species responded similarly throughout, but gave lower translocation yields than the mouse. The effects of the first and third types of fractionation were similar to those described previously in the mouse, and suggested that a first radiation dose modifies the spermatogonial population so that its sensitivity to a dose 24 h later is altered, and that repeated radiation doses result in development of resistance to translocation induction. After 8-week fractionation the results suggested that in guinea-pigs and hamsters the spermatogonial population had not returned to normal by 8 weeks after the first dose, whereas in the mouse normal sensitivity had returned by this time. The results, reported previously, of single doses of X-rays suggest that the spermatogonial population consists of fractionated doses in the mouse suggest that the sensitive and resistant types represent different phases of the same cell type rather than two distinct types of cell. In the guinea-pig and hamster this question remains open.     

Dose dependency of time to death in single and mixed infections with a wildtype and egt deletion strain of Helicoverpa armigera nucleopolyhedrovirus

Recombinant insect nucleopolyhedroviruses lacking the egt gene generally kill their hosts faster than wild-type strains, but the response of insects to mixtures of virus genotypes is less well known. Here, we compared the survival time, lethal dose and occlusion body yield in third instar larvae of Helicoverpa armigera (Hübner) after challenge with wild-type H. armigera SNPV (HaSNPV-wt), a strain with a deletion of the egt gene, HaSNPV-LM2, and a 1:1 mixture of these two virus strains. A range of doses was used to determine whether the total number of OBs influenced the response to challenge with a mixture of virus strains versus single strains. At high virus doses, HaSNPV-LM2 killed H. armigera larvae significantly faster (ca. 20 h) than HaSNPV-wt, but at low doses, there was no significant difference in survival time between the viruses. The survival time after challenge with mixed virus inoculum was significantly different from and intermediate between that of the single viruses at high doses, and not different from that of the single viruses at low doses. No differences in lethal dose were found between single and mixed infections or between virus genotypes. The number of occlusion bodies produced per larva increased with time to death and decreased with virus dose, but no significant differences among virus types were found.     

Quantifying the performance of two different types of commercial software programs for 3D patient dose reconstruction for prostate cancer patients: Machine log files vs. machine log files with EPID images

We clarified the reconstructed 3D dose difference between two different commercial software programs (Mobius3D v2.0 and PerFRACTION v1.6.4).Five prostate cancer patients treated with IMRT (74 Gy/37 Fr) were studied. Log files and cine EPID images were acquired for each fraction. 3D patient dose was reconstructed using log files (Mobius3D) or log files with EPID imaging (PerFRACTION). The treatment planning dose was re-calculated on homogeneous and heterogeneous phantoms, and log files and cine EPID images were acquired. Measured doses were compared with the reconstructed point doses in the phantom. Next, we compared dosimetric metrics (mean dose for PTV, rectum, and bladder) calculated by Mobius3D and PerFRACTION for all fractions from five patients.Dose difference at isocenter between measurement and reconstructed dose for two software programs was within 3.0% in both homogeneous and heterogeneous phantoms. Moreover, the dose difference was larger using skip arc plan than that using full arc plan, especially for PerFRACTION (e.g., dose difference at isocenter for PerFRACTION: 0.34% for full arc plan vs. −4.50% for skip arc plan in patient 1).For patients, differences in dosimetric parameters were within 1% for almost all fractions. PerFRACTION had wider range of dose difference between first fraction and the other fractions than Mobius3D (e.g., maximum difference: 0.50% for Mobius3D vs. 1.85% for PerFRACTION), possibly because EPID may detect some types of MLC positioning errors such as miscalibration errors or mechanical backlash which cannot be detected by log files, or that EPID data might include image acquisition failure and image noise.     

Effets de la novobiocine sur le fonctionnement du foie: I. Etude clinique

A case of novobiocin-induced jaundice is described in which the main feature was elevated unconjugated bilirubin in the serum. No evidence of hemolysis or hepato-cellular failure was demonstrated.The effect of novobiocin on serum bilirubin was studied by administering 2 g. of the drug daily in four divided oral doses for two days. An increase in serum unconjugated bilirubin was nearly always observed in the normal subjects and in patients with cirrhosis of the liver. This rise was particularly significant in three patients with hemolytic anemia and in two patients with Gilbert''s disease. After an oral dose of 500 mg. the BSP clearance was decreased after one hour and it was close to normal after three hours. Since hemolysis is not responsible for this elevation of serum unconjugated bilirubin, the novobiocin-induced hyperbilirubinemia appears to be due to a direct effect of the drug upon the liver.