Trichostrongylus colubriformis, T. vitrinus and T. retortaeformis infection in New Zealand possums.
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Letter↗
Biomedical subjects
D D Heath
Publications and source records attributed to D D Heath.
Vaccination against hydatidosis using a defined recombinant antigen.
Echinococcus granulosus is the causative agent of hydatid disease in humans and animals. Natural transmission of the parasite occurs between dogs as definitive hosts and animal intermediate hosts. There is an urgent need for improved methods to control the parasite's transmission. Here we describe the development of a vaccine based on a cloned recombinant antigen from the parasite egg (oncosphere). Sheep-vaccinated with the antigen, designated EG95, are protected (mean 96-98%) against hydatidosis developing from an experimental challenge infection with E. granulosus eggs. The vaccine will provide a valuable new tool to aid in control of transmission of this important human pathogen. It also has the potential to prevent hydatid disease directly through vaccination of humans.
Amino Acid Sequence↗
Ecological interaction between sympatric Mytilus species on the west coast of Canada investigated using PCR markers.
M. californianus is the dominant marine mussel species on exposed rocky shores, while M. trossulus is usually the dominant mussel species in more sheltered waters on the west coast of North America. Since these species are physical indistinguishable when small (< 10.0 mm), we developed two polymerase chain reaction (PCR) -based markers to discriminate between them. Using these markers, we identified mussels taken from an exposed coast (n = 114), a sheltered harbour (n = 80), and an upper-intertidal pool (n = 42) on the west coast of Vancouver Island, British Columbia, Canada. M. californianus were found only on the open coast. Small M. trossulus (< 20.0 mm) were common to all three sample sites, but were extremely rare at larger sizes (> 20.0 mm) on the open coast. Our results indicate that M. californianus are excluded from sheltered waters via early life factors, while M. trossulus are excluded from the open coast due to mortality later in life.
Animals↗
Selective intra-arterial infusion of high-dose cisplatin in patients with advanced head and neck cancer results in high tumor platinum concentrations and cisplatin-DNA adduct formation.
A group of 23 patients with advanced head and neck cancer were treated with highly selective intra-arterial (IA) cisplatin 150 mg/m2 delivered rapidly through microcatheters. The systemic effects of cisplatin were neutralized by concurrent administration of sodium thiosulfate. Two-to-threefold higher tumor platinum contents were detected in tumor biopsies after selective IA cisplatin administration compared to historical controls (treated with 100 mg/m2 IA). Cisplatin-induced DNA modification in human tumor biopsies was quantitated using the antiserum NKI-A59. High levels of cisplatin DNA adducts were detected which correlated linearly with the tumor platinum content (r2 = 0.62). The addition of radiotherapy to this high dose intensity cisplatin treatment resulted in a 92% complete response (CR) rate (12 of 13 patients achieved a CR). Since no difference in tumor platinum content was detected between patients receiving or not receiving radiotherapy (13 and 10 patients, respectively), but the response rate was substantially different (12 CR and 1 partial response with radiotherapy versus 6 partial and 4 non-responders without radiotherapy), these data suggest that the high platinum levels achieved by selective IA infusion were sufficient to produce enough interaction with radiotherapy to cause a 92% CR rate. Whether this interaction is additive or synergistic is as yet unclear.
Antineoplastic Agents↗
Taenia ovis recombinant vaccine--'quo vadit'.
Several years have elapsed since the publication by Johnson et al. (1989) of the cloning of a recombinant antigen from the cestode parasite Taenia ovis which stimulated high levels of protective immunity in sheep. A great deal of subsequent research and development was necessary to bring the fledgling vaccine to the point of being a registered commercial product. The results of these subsequent studies are dealt with briefly in this paper, including the results of field trials. The T. ovis vaccine was registered by the New Zealand Animal Remedies Board in February 1994. Where then is the commercial product? This paper gives a background to market problems which have emerged through the politics (and realities) of the NZ T. ovis control campaign. It serves as notice that the best science dedicated to producing vaccines or products for parasitic, or other, diseases often faces significant hurdles in the real world of commerce and politics.
Animals↗
Registration of generic alternatives to praziquantel for the control of Taenia ovis.
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Letter↗
Cross-resistance between cisplatin, antimony potassium tartrate, and arsenite in human tumor cells.
Cross-resistance between cisplatin (DDP) and metalloid salts in human cells was sought on the basis that mechanisms that mediate metalloid salt cross-resistance in prokaryotes are evolutionarily conserved. Two ovarian and two head and neck carcinoma cell lines selected for DDP resistance were found to be cross-resistant to antimony potassium tartrate, which contains trivalent antimony. The DDP-resistant variant 2008/A was also cross-resistant to arsenite but not to stibogluconate, which contains pentavalent antimony. A variant selected for resistance to antimony potassium tartrate was cross-resistant to DDP and arsenite. Resistance to antimony potassium tartrate and arsenite was of a similar magnitude (3-7-fold), whereas the level of resistance to DDP was greater (17-fold), irrespective of whether the cells were selected by exposure to DDP or to antimony potassium tartrate. In the resistant sublines, uptake of [3H]-dichloro(ethylenediamine) platinum(II) was reduced to 41-52% of control, and a similar deficit was observed in the accumulation of arsenite. We conclude that DDP, antimony potassium tartrate, and arsenite all share a common mechanism of resistance in human cells and that this is due in part to an accumulation defect.
Anions↗
A defined antigen for the serodiagnosis of Taenia ovis infections in dogs.
The evaginated scolex of Taenia ovis secretes an antigen complex into defined culture medium that has been used to develop a cestode-specific enzyme-linked immunosorbent assay (ELISA). We now describe an immunoblot test for antibodies to T. ovis based on the recognition of a 94-kDa antigen band in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile of T. ovis scolex secretions. The test was specific for cestode infections in dogs and was 82% sensitive for the recognition of T. ovis infections. Affinity-purified antibody uniquely recognizing this 94-kDa band was used to screen a cDNA expression library constructed utilizing mRNA from newly evaginated T. ovis scoleces. The cDNA from putative positive bacteriophage were subcloned into the plasmid pGEX and expressed as fusion proteins with schistosome glutathione-S-transferase (GST). The expressed fusion proteins were purified using glutathione-agarose beads. The recombinant parasite antigen was either eluted as a fusion protein with GST or cleaved from GST using a restriction protease. Some dog sera reacted with the GST molecule. However, the recombinant cleaved antigen from 1 clone, T. ovis 40, showed 42% sensitivity and 100% specificity for cestodes in an ELISA using test sera from dogs monospecifically infected with T. ovis and preabsorbed with bacteria. Some sera from dogs monospecifically infected with other cestode species (Taenia pisiformis, 30%; Taenia hydatigena, 30%; Echinococcus granulosus, 20%) reacted with the cloned antigen.
Animals↗
Cross-resistance between cisplatin and antimony in a human ovarian carcinoma cell line.
The metal compound cisplatin (DDP) is a widely used anticancer agent but naturally occurring and acquired resistance to DDP limits its effectiveness. Resistance is associated with a decreased accumulation of DDP and increased levels of glutathione and metallothioneins. Such changes also serve as protective and detoxification mechanisms for other metal salts in prokaryotes and lower eukaryotes. The aim of this study was to find metal salts for which the cross-resistance profile was the same as for DDP in sublines of the parental 2008 human ovarian carcinoma cells selected with either DDP (2008/C13*5.25) or CdCl2 and ZnCl2 (2008/MT). Among the metal salts tested the resistance profile of trivalent antimony most closely resembled that of DDP. DDP-selected cells were 15-fold resistant to DDP and 4.4-fold cross-resistant to antimony potassium tartrate, whereas of the cations tested (Cd2+, Zn2+, Ni2+ and Co2+) cross-resistance was observed only for Cd2+ (2.4-fold). When 2008 cells were selected for resistance to antimony (6.6-fold) they were found to be 16-fold cross-resistant to DDP. Accumulation of the DDP analogue cis-[3H]dichloro(ethylenediamine)platinum(II) was 59% lower in the DDP-selected subline and 48% lower in the antimony-selected variant than in the parental cell line. We conclude from the mutual cross-resistance to DDP and antimony potassium tartrate and from the impaired uptake of [3H]DEP in both the DDP and antimony-selected variants that DDP and antimony share a common mechanism of resistance. The significance of this observation lies in the fact that several evolutionarily conserved mechanisms for antimony detoxification are already known in lower organisms which may point the way to identification of additional DDP resistance mechanisms in mammalian cells.
Antimony↗
Ultrastructure of oncosphere and early stages of metacestode development of Echinococcus granulosus.
The ultrastructure of the oncospheres and developing metacestodes in vitro of Echinococcus granulosus was studied with emphasis on the origin of the laminated layer. The activated oncospheres measured 28 microns (S.D. = 1.83), and by day 5 of in vitro culture the metacestodes attained diameters up to 52 microns (S.D. = 2.66). The oncospheral plasma membrane of the tegument appeared to be formed by a microtubular cytoskeleton arranged in a predetermined pattern. By day 2 there were three main types of vesicles in the perikaryon: Vd, Vg1 and Vg2. Vesicles appeared to be synthesized in the perikaryon and continuously transported to the periphery, where the Vd vesicles could contribute to the ground substance of the syncytial tegument. We suggest that the Vg1 and Vg2 vesicles contribute to the laminated layer where, by day 5, they were seen in increased density and forming aggregations on the outer border.
Animals↗
Echinococcus granulosus: the mechanism of oncosphere lysis by sheep complement and antibody.
A heat-labile component of normal sheep serum (56 degrees C for 30 min but not 50 degrees C for 30 min) was able to lyse oncospheres in vitro. The degree of effect, and the proportion of oncospheres lysed, was related to the concentration of normal unheated sheep serum complement, or other sources of complement (rabbit, mouse) in the culture. Lower concentrations were required for lysis if the culture serum was obtained from sheep immune to E. granulosus infection. Heat inactivation of normal or immune sheep serum removed any lytic ability. No lysis occurred in any concentration of unheated foetal lamb serum. However, unheated foetal lamb serum was able to restore the lytic effect to heated normal or immune serum. This suggests that lysis in both immune and normal serum is antibody-dependent and complement-mediated. The lysis in normal serum would appear to be due to natural cross-reacting antibodies that can fix complement at the oncosphere surface. The complement lesion resulted in damage to the plasma membrane. This then peeled back, predisposing the oncosphere to osmotic destruction. The use of bleach to dissolve the embryophore caused damage to the plasma membrane similar to that caused by complement. Developing metacestodes at 3 days of age in vitro in immune serum were susceptible to the addition of complement at that time.
Animals↗
DNA fingerprinting used to test for family effects on precocious sexual maturation in two populations of Oncorhynchus tshawytscha (Chinook salmon).
Two single locus Variable Number Tandem Repeat (VNTR) DNA probes were used to test for differences in allele distribution between precociously mature male and immature chinook salmon, Oncorhynchus tshawytscha. Two populations were examined: Robertson Creek (RC) adult salmon, and Nicola River (NR) freshwater juveniles, or parr. Genomic DNA was extracted from 74 RC precociously mature adult males ('jacks') and 94 RC immature adults of the same age and from 45 NR precociously mature parr and 51 NR nonmaturing parr. The genomic DNA was hybridized with a single locus VNTR probe developed for chinook salmon (OtSL1), as well as one developed for Atlantic salmon, Salmo salar (Ssa1). The allele frequency distributions at both loci were significantly different for the RC jacks and immature fish, indicating a family effect on the incidence of precocious maturation in that population. No difference was found between the allele frequency distribution of the NR precocious and immature parr. A bin width sensitivity analysis showed that the comparisons of the allele frequency distributions were insensitive to the choice of bin size. No differences in heterozygosity were found between mature and immature fish at either locus for both stocks. Preliminary testing for family effects on phenotypes of interest, such as alternative life history strategies, can be performed using hypervariable VNTR DNA probes, prior to implementing costly and involved breeding programmes.
Alleles↗
Resistance against Taenia hydatigena in sheep after passive transfer of serum or colostrum.
The role of antibody in the resistance of sheep to infection with Taenia hydatigena metacestodes was examined using passive transfer of immunoglobulin. The immunoglobulin either was experimentally transferred in serum, or was transferred from immune ewes to their new-born lambs in colostrum. Pooled serum from donor lambs which had received one, light, oral infection did not protect recipients although the donors themselves were immune. However, transfer of pooled serum from donors which had either received three oral infections, or three immunizations with solubilized T. hydatigena oncospheres in a water-in-oil adjuvant, resulted in 70-80% fewer cysts in the recipients. Colostrum from ewes infected with three high or low doses of T. hydatigena eggs was transferred to their lambs. A short acting protection (one to three weeks) was observed in the lambs. Comparisons by ELISA and Western blot, of the anti-T. hydatigena oncosphere antibody content of the donor sera, the sera of the recipients collected 24 h and seven days after transfer, the sera of the lambs and ewes, and the colostrum of the ewes, indicated that resistance to the challenge infection depends upon a critical level of antibody.
Animals↗
PCR primed with VNTR core sequences yields species specific patterns and hypervariable probes.
The use of genomic DNA-based techniques in ecological and evolutionary studies has been limited by the availability of suitable probes for species of interest due to the technical difficulty of isolating and applying such probes. We have developed a simple technique that directs polymerase chain reaction (PCR) amplification to regions rich in variable number of tandem repeats (VNTRs). By using published VNTR core sequences as primers in PCRs, fragments were amplified that showed little variation within a species, but did show differences between species. When the amplified fragments were used as probes with genomic DNA Southern blots they produced hypervariable single-locus or few-locus patterns in fish, birds, and humans. We have named this procedure as Directed Amplification of Minisatellite-region DNA (DAMD).
Animals↗
Identification of host-protective antigens of Taenia ovis oncospheres.
Sheep were fully protected against challenge infection following immunization with a homogenate of T. ovis oncospheres. Ultracentrifugation of sonicated oncospheres either alone or in the presence of a range of detergents did not reduce the immunogenicity of the extracts. Solubilization of oncosphere extracts in non-ionic detergents or sodium dodecyl sulphate (SDS) enabled analysis of host-protective antigens by isoelectric focusing (IEF) and electrophoresis in polyacrylamide gels (SDS-PAGE), respectively. Immunoblotting analysis of oncosphere antigens with immune sheep sera identified predominantly two groups of antigens with relative mobilities of 31-34 kDa and 47-52 kDa with a common isoelectric point of 5.8. The immunogenicity of these antigens was confirmed in vaccination trials using appropriate fractions cut from SDS-PAGE gels and agarose IEF gels. Affinity-purified antibodies prepared against the candidate antigens were used to select the corresponding recombinant DNA-derived polypeptides, one of which was subsequently found to be host-protective.
Animals↗
Regional lymphatic drug exposure following intraperitoneal administration of 5-fluorouracil, carboplatin, and etoposide.
Intraperitoneal (i.p.) administration of chemoterapeutic agents results in greater total drug exposures in the peritoneal cavity than in plasma. A study on the drug exposure for i.p. lymphatics of pigs, receiving 5-fluorouracil (5-FU), etoposide (VP-16) and carboplatin (CBDCA) by the i.p. route was conducted. Drug concentrations in peritoneal fluid, plasma, and thoracic duct lymph were monitored over the ensuing 3 h. 5-FU appeared rapidly in thoracic duct, lymph and plasma. The lymph concentration declined after 20 min while the plasma concentration remained stable. CBDCA reached a stable concentration in lymph and plasma after 60 min. VP-16 peaked in the lymph after 20 min, whereas the plasma concentration continued to rise for 150 min; the peritoneal half-life for VP-16 was too long for clearance to be defined. Total drug exposure (AUC) was for 5-FU 5.7-fold greater for lymph than for plasma and for CBDCA equal in both compartments. VP-16 had a 2.1-fold higher AUC for lymph than for plasma. The results indicate that the i.p. route of administration results in a greater exposure of the lower thoracic duct lymph than the plasma to 5-FU, produces only a marginally increased exposure to VP-16, and results in no difference for CBDCA. The efficacy of 5-FU is a function of total drug exposure. The results reported provide a strong rationale for evaluating the adjuvant use of i.p. 5-FU in colorectal and gastric carcinoma.
Animals↗
Selective modulation of vinblastine sensitivity by 1,9-dideoxyforskolin and related diterpenes in multidrug resistant tumour cells.
The ability of 1,9-dideoxyforskolin (DDF), 1-deoxyforskolin (DF) and forskolin to modulate cellular sensitivity to vinblastine (VBL) was examined in drug-sensitive parental KB-3-1 cells and a multidrug-resistant subline, KB-GRC1, derived by transfection of mdr1. Fifty microM DF and forskolin enhanced the 1 h uptake of VBL by 8.0 +/- 0.7 (s.d.) and 4.7 +/- 2.5-fold, respectively, with 50 microM DDF producing a 13.6 +/- 1.9-fold increase. The greater effect of DDF relative to forskolin indicated that the effect was independent of activation of cAMP, and this was supported by a lack of effect of dibutyryl cAMP on the uptake. The effect of these agents on uptake were < or = 1.4-fold in KB-3-1 cells. DDF selectively inhibited initial efflux in cells expressing a functional P-glycoprotein (PGP), but both forskolin and DDF inhibited the terminal phase of efflux irrespective of PGP expression. Neither agent affected membrane permeability of polarisation and forskolin did not enhance the uptake of VBL in protein-free liposomes. At a non-toxic concentration of 20 microM, DDF and forskolin decreased the IC50 of VBL from 18.9 to 2.7 and 13 nM in KB-GRC1 cells, respectively, and DDF acted synergistically with VBL as shown by median effect analysis [combination index = 0.20 +/- 0.05 (s.d.)]. In contrast, these diterpenes did not affect VBL sensitivity in KB-3-1 cells. These results indicate that the diterpenes modulate VBL sensitivity predominantly by inhibiting PGP-mediated efflux activity.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Phase I/pharmacokinetic study of high-dose progesterone and doxorubicin.
PURPOSE: We developed a new formulation of progesterone that permits administration of up to 10 g of progesterone as a continuous intravenous infusion over 24 hours and conducted a phase I clinical trial to determine whether progesterone could modulate the in vivo cytotoxicity of the P-glycoprotein substrate doxorubicin. PATIENTS AND METHODS: Thirty-four patients with advanced malignancies were treated with increasing doses of progesterone and a fixed dose of 60 mg/m2 of doxorubicin given as an intravenous bolus 2 hours after starting a 24-hour intravenous infusion of progesterone. RESULTS: Progesterone enhanced doxorubicin-induced myelotoxicity in a dose-dependent fashion without altering the pharmacokinetics of doxorubicin. The steady-state plasma concentration of progesterone at a dose level of 4 g was 4.1 +/- 0.9 mumol/L, which was higher than the minimal concentration required to reverse multidrug resistance (MDR) in vitro. CONCLUSION: Progesterone enhanced the hematologic toxicity of doxorubicin without altering its pharmacokinetics, suggesting that progesterone could modulate P-glycoprotein at the level of pluripotent hematopoietic stem cells. Adequate tissue concentrations of progesterone could be achieved in vivo to modulate doxorubicin toxicity in the bone marrow and thus potentially in tumor tissue as well. Selectivity may potentially be gained by using hematopoietic growth factors to offset the enhanced hematologic toxicity of doxorubicin while leaving the enhancement of toxicity to tumor cells unchanged.
Adult↗