Changes in cardiovascular performance, biochemistry, gastric motility and muscle temperature induced by acute exercise on a treadmill in healthy military dogs.

Changes in physiological parameters that are induced by acute exercise on a treadmill in healthy military dogs have not been thoroughly investigated, especially with regard to age. This study investigated the effects of acute exercise on a treadmill on cardiovascular function, biochemical parameters and gastric antral motility in military dogs. Thermography was used to assess variations in superficial hindlimb muscle temperature. Nine healthy dogs were distributed into three groups according to their age (Group I: 25 ± 7 months; Group II: 51 ± 12 months; Group III: 95 ± 10 months) and sequentially subjected to running exercise on a treadmill for 12 min (3.2 km/h at 0° incline for 4 min, 6.4 km/h at 0° incline for 4 min and 6.4 km/h at 10° incline for 4 min). Heart rate, systolic and diastolic arterial pressure (DAP), gastric motility, haematocrit and biochemical analyses were performed at rest and after each session of treadmill exercise. Infrared thermographic images of muscles in the pelvic member were taken. Exercise decreased DAP in Group I, increased systolic arterial pressure in Groups II and III and increased mean arterial pressure in Group III (all p < 0.05). After the exercise protocol, plasma creatine kinase and aspartate aminotransferase levels increased only in Group I (p < 0.05). Exercise increased heart rate and decreased the gastric motility of a solid meal at 180 min in all groups (all p < 0.05). Exercise also elevated temperature in the femoral biceps muscles in Group I compared with the older dogs. The results indicate that acute exercise decreased gastric motility in dogs, regardless of age, and caused more pronounced cardiovascular changes in older dogs than in younger dogs. Acute exercise also altered biochemical parameters and superficial hindlimb muscle temperature in younger military dogs.

Leishmania infantum: Lipophosphoglycan intraspecific variation and interaction with vertebrate and invertebrate hosts.

Interspecies variations in lipophosphoglycan (LPG) have been the focus of intense study over the years due its role in specificity during sand fly-Leishmania interaction. This cell surface glycoconjugate is highly polymorphic among species with variations in sugars that branch off the conserved Gal(ß1,4)Man(α1)-PO(4) backbone of repeat units. However, the degree of intraspecies polymorphism in LPG of Leishmania infantum (syn. Leishmania chagasi) is not known. In this study, intraspecific variation in the repeat units of LPG was evaluated in 16 strains of L. infantum from Brazil, France, Algeria and Tunisia. The structural polymorphism in the L. infantum LPG repeat units was relatively slight and consisted of three types: type I does not have side chains; type II has one ß-glucose residue that branches off the disaccharide-phosphate repeat units and type III has up to three glucose residues (oligo-glucosylated). The significance of these modifications was investigated during in vivo interaction of L. infantum with Lutzomyia longipalpis, and in vitro interaction of the parasites and respective LPGs with murine macrophages. There were no consequential differences in the parasite densities in sand fly midguts infected with Leishmania strains exhibiting type I, II and III LPGs. However, higher nitric oxide production was observed in macrophages exposed to glucosylated type II LPG.

Carbohydrate and LPG expression in Leishmania viannia subgenus.

Glycosylated molecules expressed on the cell surface of Leishmania promastigotes contribute to the outcome of contact between the parasite and its invertebrate and vertebrate hosts. The expression of several such molecules is growth phase dependent. Information on the expression of carbohydrates by Leishmania of the Viannia subgenus (braziliensis complex), a widespread cause of morbidity in the Americas, is fragmentary. We have examined the relationship between growth phase and the expression of glycosylated surface structures in WHO reference strains of 3 species of the Viannia subgenus, i.e., L. panamensis, L. guyanensis, and L. braziliensis. Agglutination with lectins and the monoclonal antibody specific for the repeat unit of L. donovani lipophosphoglycan, CA7AE, distinguished logarithmic and stationary-phase promastigotes of all 3 species. Flow cytometry revealed increased heterogeneity and disparity in the expression of the repeat unit epitope in stationary-as compared to logarithmic-phase promastigotes. Biochemical analyses showed the LPG repeat unit of all 3 species reference strains to be constituted by mannose and galactose with little or no substitution and, hence, to be similar to the LPG of L. donovani. Initial quantitative analyses of L. braziliensis LPG indicated a 10-fold lower quantity of LPG in this species than L. donovani and an increase in the size of LPG in the stationary phase. These findings provide bases for isolating and biologically characterizing phenotypically distinct populations of promastigotes and for identifying molecular determinants of the host parasite-relationship among Leishmania Viannia.

Isolation of virulence genes directing GPI synthesis by functional complementation of Leishmania.

Recent advances in molecular genetics of Leishmania parasites prompted us to develop methods of functional genetic complementation in Leishmania and apply them to the isolation of genes involved in the biosynthesis of the virulence determinant LPG, an abundant GPI-anchored polysaccharide. LPG1, the gene product identified by complementation of our R2D2 LPG- mutant, may be a glycosyltransferase responsible for the addition of galactofuranose to the nascent chain. As galactofuranose is not found in mammalian cells, inhibition of the addition of this sugar could be exploited for chemotherapy. Overall, the success of the functional complementation approach opens the way to the identification of a variety of genes involved in pathogenesis and parasitism.

Isolation of virulence genes directing GPI synthesis by functional complementation of Leishmania

Recent advances in molecular genetics of Leishmania parasites prompted us to develop methods of functional genetic complementation in Leishmania and apply them to the isolation of genes involved in the biosynthesis of the virulence determinant LPG, an abundant GPI-anchored polysaccharide. LPG1, the gene product identified by complementation of our R2D2 LPG- mutant, may be a glycosyltransferase responsible for the addition of galactofuranose to the nascent chain. As galactofuranose is not found in mammalian cells, inhibition of the addition of this sugar could be exploited for chemotherapy. Overall, the success of the functional complementation approach opens the way to the identification of a variety of genes involved in pathogenesis and parasitism

Evaluation of an aseptic technique testing and challenge kit (ATTACK).

Currently, there is considerable discussion and concern about quality assurance when sterile pharmaceuticals are prepared by pharmacists and other health professionals. This study describes the utility of a kit made by Marsam Pharmaceutics Inc. in detecting microbial contamination during simulated drug transfers by syringe. Common microbial detection techniques were incorporated in a simple series of transfers intended to simulate actual use. Growth promotion studies were carried out using Trypticase Soy Broth initially in tubes and then in vials (as supplied in the kit). Three test organisms were employed (Staphylococcus epidermidis, Bacillus subtilis, and Candida albicans) and inoculated at three levels, < 1000, < 100, and < 10 CFU/mL. All studies demonstrated growth occurring in 100% of the trials in 8 days. Similar studies were initiated in stored media (32 month) to determine the effects of time on the ability of the medium to support growth. Growth promoting ability of 32 month old media showed no significant difference. 100% of the vials inoculated showed growth in 8 days. Once the growth promoting qualities of the medium and vials was established a kit was developed then a study to determine the effectiveness of the kit as used was undertaken. Kits were manipulated according to the directions for use by a trained individual, under aseptic conditions and by an untrained individual in an area described as less than desirable. No growth occurred in the vials of the 10 kits used to illustrate good technique and good environmental conditions with 30% (3 of 10) of the kits showing contamination when transfers by syringe were carried out in the less than desirable setting.(ABSTRACT TRUNCATED AT 250 WORDS)

Mapping size distributions of parenteral fluorocarbon emulsions by a novel method of centrifugal sedimentation followed by densitometry.

A novel method for characterization of size distributions of parenteral fluorocarbon emulsions is described. Prepared emulsions were centrifuged to sediment droplets above predetermined diameters out of a known supernatant sample volume using the Bostok-Stoke's equation. Centrifugation times may be calculated using centrifuge parameters and physical properties of the fluorocarbon oil phase and the dispersion medium. The fluorocarbon content of the supernatant sample volume at successive centrifugation times was determined both by densitometry and by Gas Chromatography. A close correlation was found between the two methods. The density data was processed and converted into a volume distribution histogram by means of a program written in BASIC. The speed, simplicity of use, non reliance on costly equipment and good correlation to absolute particle counting methods makes the density method suitable for submicron size characterization.

The influence of manufacturing parameters on the formation and growth on autoclaving of a 40% V/V Bis-Perfluorobutylethene emulsion.

The influence of different process variables on the number of large particles before and after autoclaving of a 40% V/V Bis-Perfluorobutylethene emulsion stabilized by egg yolk lecithin, made isotonic with blood, was examined. The concentration of emulsifier, emulsification and autoclaving time and temperature, fill volume and the cooling gradient applied to the emulsion after autoclaving all affect the number of large droplets and hence the stability and acceptability of the finished product. This work suggests that validation of equipment and process to very exacting specifications and strict adherence to specified manufacturing protocol is essential for the reproducible production of fluorocarbon emulsions acceptable for intravenous administration.