摘要:

SummaryIt has been concluded from previous experiments involving the growth of segmental nerves from the amphibian spinal cord to the limb‐bud that axons are attracted to the limb‐bud region by their target tissue (Hamburger, 1929; Hughes and Tschumi, 1958). In the present study this hypothesis has been tested by obstructing the pathways over which the nerves normally grow. It was found that for those nerves which were marginally obstructed far fewer axons were able to reach their target. The spinal ganglia associated with these nerves contained up to 50% fewer cells than the adjacent unobstructed segmental level. These results suggest that nerves are not attracted from the spinal cord by the target tissue, but rather that the pathways provided by the axial segmental nerves are essential if a normal number of axons are to reach their target.

ISSN:0004-945X    

DOI:10.1038/icb.1982.14

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryComparisons were drawn between the effects ofNippostrongylus brasilensisinfestation upon IgE synthesis and thein vivoexpression of allergic reactions to ovalbumin OV) in weanling, juvenile and adult rats. Parameters examined included total and antigen (OV)‐specific IgE levels in serum and the relationship between serum levels of antigen‐specific IgE in individual parasitized rats and the magnitude of their subsequent reaction to intravenous or intradermal antigenic challenge. On the basis of parallel trials employing non‐infested age‐mulched controls, parasitized adult and juvenile animals manifested allergic reactivity to the full potential of their individual specific antibody levels. In contrast, the magnitude of allergic reactions in parasitized weanlings was markedly depressed below that expected from their IgE antibody scores. The most notable additional feature distinguishing parasitized weanling rats from infested animals of other ages was the presence in their serum of extremely high levels of ‘irrelevant’ IgE.

ISSN:0004-945X    

DOI:10.1038/icb.1982.15

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryDuringin vitroincubation in Krebs Ringer phosphate (KRP) medium, rat erythrocytes about 20% parasitized withB. rodhainiused two to four times as much glucose as unparasitized erythrocytes. However, the ATP concentration and ATP production of parasitized erythrocytes decreased. For example, before incubation the ATP concentration in parasitized erythrocytes was significantly higher than unparasitized erythrocytes, but following 0·5 h incubation it was reduced to about the same as in unparasitized erythrocytes.Addition of 5 × 10−3M adenosine to the basal medium increased the ATP production and the adenylate energy charge of parasitized erythrocytes. Infectivity tests in susceptible mice showed that, despite these seemingly favourable changes in energy metabolism, adenosine had no detectable effect on the survival ofB. rodhaini.Absence of infectivity showed the inability of KRP medium to supportB. rodhainifor 22 hin vitrowith or without adenosine.Adenosine also greatly decreased the glucose uptake by parasitized erythrocytes, apparently by competitive inhibition, since lactate production was unchanged.

ISSN:0004-945X    

DOI:10.1038/icb.1982.16

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryThe effect on the haemoprotozoan parasiteBabesia rodhainiof adding a zwitterion buffer, HEPES, to a basal medium was studied by comparing the glucose uptake, ATP concentration, medium pH and infectivity of parasitized rat erythrocytes every 4 h during 24 h incubation in either Krebs Ringer phosphate (KRP) or KRP plus 28 mM HEPES. KRP plus HEPES was found to be superior to KRP for the maintenance of glucose uptake, erythrocyte ATP concentration, medium pH and infectivity of the parasite.Having established that HEPES improved the basal KRP medium, HEPES was then compared to three other buffers TES, BES and TRIS, to determine their relative effects onB. rodhainiduring 18 h of incubation. At 28 and 56 mM concentration there was no significant difference in glucose uptake or lactate production among the 4 buffers. However, TES maintained the medium pH best, and BES preserved the infectivity of the parasite best. Further comparison of TES and BES at 10, 20, 30 and 40 mM established 40 mM TES to be best for buffering the pH of the medium and maintaining infectivity ofB. rodhaini.

ISSN:0004-945X    

DOI:10.1038/icb.1982.17

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryThein vitroamino acid production byBabesia rodhaini, Plasmodium bergheiand uninfected rat erythrocytes was determined following 4 and 18 h of incubation in Krebs Ringer medium. Both parasites produced excess free amino acid.B. rodhainiproduced up to 150 times andP. bergheiup to 1,100 times as much free amino acid as parasite‐free rat erythrocytes. The composition of excess amino acids produced by both parasites had a statistically significant concordance with the amino acid composition of rat haemoglobin, suggesting that haemoglobin was probably the main source of the amino acids produced by the parasites.

ISSN:0004-945X    

DOI:10.1038/icb.1982.18

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryThe course of infection withStrongyloides rattiwas examined in congenially hypothymic CBA/H, C57B1/6 and BALB/c nude mice. The intensity of infection and the duration of faecal larval excretion were both increased in nude mice when compared with intact mice. Adult worms persisted in the small intestine of nude mice for at least 6 weeks. Greater worm burdens were found in such mice after subcutaneous injection as compared with percutaneous infection. Hypothymic mice did not acquire resistance to re‐infection. It is concluded that both the spontaneous expulsion of worms in primary infection and resistance to challenge infection are T cell‐dependent events. Autoinfection was not seen.

ISSN:0004-945X    

DOI:10.1038/icb.1982.19

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryThe therapeutic efficiency of 16 anti‐microbial agents (Ethopabate, Nicarbazin, Sulphaquinoxaline, Furaltadone, Enterolyte‐N, Sulphamethazine, Trinamide, Amprol, Phenamidine, Zoaquin, Halofuginone, Salinomycin, Monensin, Emtryl, Arprinocid and Amprolium) were examined againstCryptosporidiuminfections in mice. TheCryptosporidiumwas originally isolated from a field outbreak of calf diarrhoea. The drugs neither prevented nor modified the course of the infection as compared with infected, untreated mice.

ISSN:0004-945X    

DOI:10.1038/icb.1982.20

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryStrong evidence has been obtained that the funnel‐web spider venom inhibitor, previously found to occur naturally in the blood of rats, is at least partly immunoglobulin in composition. However, the results of chromatographic and immunological studies, including the use of specific antisera, indicate that this inhibitor is not a single chemical entity and apparently resides within more than one immunoglobulin class. In addition, it was observed that challenge of rats withAtraxvenom substantially increased the venom‐inhibiting powers of their blood and that these powers were located in the same plasma fractions as in unchallenged rats.

ISSN:0004-945X    

DOI:10.1038/icb.1982.21

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryFifty‐twoRickettsia tsutsugamushiisolates from humans, rodents and chiggers in North Queensland were serologically characterized by the direct immunofluorescence test. A majority (71%) of the isolates was a mixture of two or more strains. The most frequently detected strains in the 52 isolates were TA716 (94%), TA763 (42%), TA686 (33%), and Karp (31%). The Gilliam strain was detected in only 4% of the isolates.

ISSN:0004-945X    

DOI:10.1038/icb.1982.22

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY

摘要:

SummaryPI phenotypes were determined from 420 cord bloods from Adelaide. Allele frequencies for the subvariantsP1*M1, P1*M2andP1*M3were 0·73, 0·14 and 0·09, respectively. The combined frequency of other alleles was 0·04. This relatively high level of variation makesPIuseful for gene mapping, paternity testing and zygosity testing. For this locus the average probability of detecting non‐paternity in this population is 28%.

ISSN:0004-945X    

DOI:10.1038/icb.1982.23

出版商:Nature Publishing Group    

年代:1982

数据来源: WILEY