Ultrasonically driven instruments in the transfemoral approach--an aid to preservation of bone stock and reduction of implant length.

The transfemoral approach to the femur with implantation of the Wagner SL stem provides a means of dealing with the difficult revision problems of extensive endosteolysis and with peri-prosthetic fractures. This surgical approach has been modified such that with the aid of an ultrasonically driven cement removal instrument (OSCAR) the length of the osteotomy is reduced, preserving bone stock, and it is possible to implant a shorter prosthesis in approximately 60% of cases.

Characterization of a Plasmodium chabaudi gene encoding a protein with glutamate-rich tandem repeats.

Several highly antigenic proteins containing tandem repeats rich in glutamic acid residues have been described in Plasmodium falciparum. However, relatively little information is available about analogous genes in rodent parasites. This report describes a 4.2-kb genomic DNA fragment from P. chabaudi with a deduced amino acid sequence that is predominantly glutamate-rich tandem repeats. Several different monoclonal antibodies raised against a 93-kDa P. chabaudi protein, which does not correspond to the cloned DNA fragment, recognize a recombinant protein expressed from the 4.2-kb DNA fragment. The only sequence similarities between these two genes are tandem repeats with a predominance of glutamate pairs followed by a hydrophobic residue. This repetitious-sequence motif may be the basis for the observed cross-reactivity. A similar motif has been demonstrated to be the basis for antibody cross-reactivity between glutamate-rich proteins of P. falciparum. The expression of multiple glutamate-rich proteins with cross-reacting epitopes may be a general phenomenon in Plasmodium species.

The complete sequence of Plasmodium berghei merozoite surface protein-1 and its inter- and intra-species variability.

The complete gene for merozoite surface protein-1 (MSP-1) from Plasmodium berghei has been cloned and sequenced. Comparison of the P. berghei MSP-1 sequence with MSP-1 from other rodent parasites reveals five conserved domains interrupted by four variable blocks. These variable blocks exhibit no sequence homology but do have similar amino acid compositions. Primary proteolytic processing sites are located near the boundaries between the conserved domains and the variable blocks. Sequencing of the variable blocks from several P. berghei isolates shows that the predominant intra-species difference is in the number of tandem repeats. The inter- and intra-species differences suggest that the variable blocks are localized areas with relatively high levels of slipped-strand mispairing, unequal crossing-over, or other intragenic recombination activity. MSP-1 from P. berghei exhibits more repetitiveness than MSP-1 from other species suggesting that P. berghei experiences a higher intrinsic level of events producing variable numbers of tandem repeats or a lower level of events leading to the degeneration of tandem repeats.

Evaluation of immunogenicity of an oral Salmonella vaccine expressing recombinant Plasmodium berghei merozoite surface protein-1.

A repetitive region of Plasmodium berghei merozoite surface protein-1 (PbMSP-1) was expressed as a fusion protein with either maltose binding protein or the B subunit of heat-labile enterotoxin from Escherichia coli. Vaccination of mice with the fusion proteins indicates that this region of PbMSP-1 is antigenic as evidenced by an antibody response. The fusion proteins were also expressed in Salmonella and mice were orally immunized with the recombinant Salmonella. Some of the vaccinated mice survived a challenge with P. berghei blood-stage parasites without developing parasitemia. All control mice became patent and succumbed to the challenge infection. This partial protection was also observed with purified recombinant protein and was independent of the adjuvant used. Mice immunized with recombinant Salmonella showed either extremely low or no antibody response to PbMSP-1, suggesting that cell-mediated immunity is important for the observed protection. These studies show that it is feasible to develop a cost effective oral vaccine against the blood stage of the malarial parasite.

Further characterization of a 58 kDa Plasmodium berghei phosphoprotein as a cochaperone.

Molecular chaperones are important for proper protein folding during protein biogenesis. This report describes a protein from Plasmodium berghei which is 30% identical and 40% similar to a recently described mammalian cochaperone, or heat shock protein 70 interacting protein. The P. berghei cochaperone accumulates throughout the trophozoite stage and decreases during the schizont stage. The stage specific expression is consistent with its presumed role in protein folding or protein-protein interactions. The largest difference between the Plasmodium and mammalian sequences is a more extensive domain of imperfect glycine-glycine-methionine-proline (GGMP) tandem repeats in the parasite's cochaperone sequence. Immunofluorescence studies show that the protein is an abundant cytosolic protein of the parasite. However, antibodies raised against the GGMP repeat domain, which is also found in other parasite chaperones, react with both the parasite and host erythrocyte membrane. The reactivity with the host membrane suggests that the parasite exports molecular chaperones into the infected erythrocyte.

Effects of chronic low doses of d-fenfluramine on weight gain and calorie intake, brown adipose tissue thermogenic parameters and brain neurotransmitter content in rats fed chow or palatable diets.

Male black-hooded rats of original age 3 months were maintained on either a standard laboratory chow diet or a palatable diet (32 animals in each group). After two months, when clear increases in weight gain and calorie intake in the latter group were evident, eight animals from each group were killed for analysis. For one further month, eight animals from each group received low doses (1-3 mg/kg/day) of d-fenfluramine in drinking water, another eight served as untreated controls, and the remaining eight were pair-fed to the treated groups. On killing, the interscapular brown adipose tissue (BAT) mass, and also BAT mitochondrial protein and uncoupling protein contents, and BAT mitochondrial cytochrome oxidase activity and GDP-binding were measured. Gross brain chemical changes were assessed by measuring whole brain contents of serotonin, noradrenaline and dopamine. The palatable diet produced clear increases in weight gain, calorie intake, total BAT mass, BAT mass with respect to body mass, total BAT mitochondrial protein and total amounts of uncoupling protein in each case; however, BAT mitochondrial protein per unit of BAT mass was not significantly increased, nor was the amount of uncoupling protein per mg of mitochondrial protein. Small, but variable, increases in brain neurotransmitter contents were observed. Drug-treated animals showed marked reductions in calorie intake and body weight compared to untreated controls but no significant decreases in body weight compared to pair-fed controls were evident. The pair-fed (i.e. 'slimming') groups displayed a decrease in BAT thermogenic parameters: d-fenfluramine partially prevented these decreases.