Cardiac Rehabilitation during COVID-19

Funding Acknowledgements

Type of funding sources: None.

Introduction

The global COVID19 pandemic has led to significant morbidity and mortality to millions of cardiac patients across the globe. Inferior clinical standards, modified clinical pathways and limited hospital resources has unfortunately translated to significant premature cardiac deaths. Cardiac rehabilitation has also been hit significantly.

Study Objectives

The aim of this study was to assess the impact of cardiac rehabilitation during COVID-19, comparing the referral, adherence and outcomes with patients admitted a year previously.

Methodology

Patients were divided in two groups. Group 1 were those admitted between March-August 2019 (Pre-COVID). Group 2 included those admitted between March-August 2020 (during COVID). Program completion was defined as adherence to ≥6 sessions (Group 1) or ≥ 4 sessions (Group 2). Data was collected from electronic case summaries and cardiac rehabilitation unit medical records. Data was tabulated in SPSS v23. Categorical variables were presented as percentages. Statistical analysis was computed with SPSS v23. A p value of <0.05 was deemed statistically significant.

Results

710 patients were admitted with a cardiac diagnosis (Group 1 n=360, Group 2 n=350), mean age 66.71 ± 13.21 years, dominant male population (n=548, 77.2%). Both groups had comparable proportions of smoking, hypertension, diabetes and hyperlipidaemia.

The referral rate to cardiac rehabilitation was rather poor in both groups, though better in Group 1 (Group 1 38.3% vs 26.6%, p=0.001), partly because of temporary discontinuation of the rehabilitation program at the start of the pandemic. The completion rate was also unfortunately quite low. It was better in Group 2, possibly because of the shorter program duration (Group 1 23.5% vs Group 2 38.7%, p=0.018).

The 1 year readmission rate was significantly higher in Group 1 (22.8% vs 15.1%, p=0.022)), possibly because patients were more open to seek medical advice before the pandemic. The 30 day death rate was comparable in both groups (5.0% vs 5.7%, p=0.672). The 1 year mortality was also comparable (Group 1 12.5% vs Group 2 10.6%, p=0.481) Cardiac rehabilitation did not impact the 1 year readmission rate, 30 day and 1 year mortality.

Conclusion

The 30 day and 1 year mortality in patients admitted during the first 6 months of the pandemic was comparable to the same timeframe the year before. The 1 year readmission rate was higher in patients admitted before COVID, possibly explained by patients being more inclined to seek medical advice. Referral to cardiac rehabilitation was generally low. Adherence to the program did not impact readmission and mortality.

Phase I of The National Beef Quality Audit-2011: quantifying willingness-to-pay, best-worst scaling, and current status of quality characteristics in different beef industry marketing sectors

The National Beef Quality Audit (NBQA)-2011 benchmarked the current status of and assessed progress being made toward quality and consistency of U.S. cattle, carcasses, and beef products after the completion of the first NBQA in 1991. Unlike previous NBQA, objectives of the 2011 Phase I study were to determine how each beef market sector defined 7 quality categories, estimate willingness-to-pay (WTP) for the same quality categories by market sector, and establish a best-worst (B/W) scaling for the quality categories. Structured face-to-face interviews were conducted and responses were recorded using dynamic routing software over an 11-mo period (February to December 2011) with decision makers in each of the following beef market sectors: Feeders (n = 59), Packers (n = 26), Food Service, Distribution, and Further Processors (n = 48), Retailers (n = 30), and Government and Allied Industries (n = 47). All respondents participated in a structured interview consisting of WTP and B/W questions that were tied to 7 quality categories and then were asked to "define" each of the 7 categories in terms of what the category meant to them, resulting in completely unbiased results. The 7 quality categories were a) how and where the cattle were raised, b) lean, fat, and bone, c) weight and size, d) cattle genetics, e) visual characteristics, f) food safety, and g) eating satisfaction. Overall, "food safety" and "eating satisfaction" were the categories of greatest and second most importance, respectively, to all beef market sectors except for Feeders. Feeders ranked "how and where the cattle were raised" and "weight and size" as the most important and second most important, respectively. Overall, "how and where the cattle were raised" had the greatest odds of being considered a nonnegotiable requirement before the raw material for each sector would be considered for purchase and was statistically more important (P < 0.05) as a requirement for purchase than all other categories except "food safety." When all market sectors were considered, "eating satisfaction" was shown to generate the greatest average WTP percentage premium (11.1%), but that WTP premium value only differed statistically (P < 0.05) from "weight and size" (8.8%). Most notably, when a sector said that "food safety" was a nonnegotiable requirement, no sector was willing to purchase the product at a discounted price if the "food safety" of the product could not be assured.

National Beef Quality Audit-2011: Harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and byproducts

The National Beef Quality Audit-2011 (NBQA-2011) was conducted to assess targeted characteristics on the harvest floor that affect the quality and value of cattle, carcasses, and byproducts. Survey teams evaluated approximately 18,000 cattle/carcasses between May and November 2011 in 8 beef processing facilities. Cattle identification methods were lot visual tags (85.7%), individual visual tags (50.6%), electronic tags (20.1%), metal-clip tags (15.7%), other (5.3%), none (2.5%), and wattles (0.5%). Hide colors or breed types were black (61.1%), red (12.8%), yellow (8.7%), Holstein (5.5%), brown (5.0%), gray (5.0%), white (1.4%), and brindle (1.0%). Brand frequencies were none (55.2%), 1 (40.4%), 2 (4.4%), and 3 or more (0.04%) brands, and brands were located on the butt (35.2%), side (9.0%), and shoulder (2.5%). Hide locations of mud or manure were no mud/manure (49.2%), legs (36.8%), belly (23.7%), side (14.9%), top-line (11.0%), and tail region (13.7%). There were 76.2% of cattle without horns, and the majority of those with horns (71.6%) were between 0 cm and 12.7 cm in length. Permanent incisor numbers were zero (87.3%), 1 (1.4%), 2 (8.0%), 3 (0.9%), 4 (1.9%), 5 (0.3%), 6 (0.2%), 7 (0.1%), and 8 (0.02%). Most carcasses (77.0%) were not bruised, 18.7% had 1 bruise, 3.4% had 2 bruises, 0.6% had 3 bruises, and 0.3% had more than 3 bruises. Bruise locations were loin (50.1%), rib (21.3%), chuck (13.8%), round (7.3%), and brisket/flank/plate (7.5%). Condemnation item and incidence were whole carcass (none recorded), liver (20.9%), lungs (17.3%), tongue (10.0%), viscera (9.3%), and head (7.2%). Compared with the NBQA-2005, the NBQA-2011 had an increased percentage of black-hided cattle (56.3 vs. 61.1%), more cattle with brands (38.7 vs. 44.8%), and more cattle with some form of identification (93.3 vs. 97.5%). In addition, there was a lesser percentage of carcasses with bruising in 2011 (23.0%) than in 2005 (35.2%), as well as a smaller percentage of carcasses with more than 1 bruise (2005 = 9.4% vs. 2011 = 4.2%). Compared with the 2005 audit, a similar percentage of the cattle were deemed 30 mo of age or older using dentition (2005 = 2.7% vs. 2011 = 3.3%). The information from NBQA-2011 helps the beef industry measure progress against previous NBQA assessments and provides a benchmark for future educational and research activities.

National Beef Quality Audit-2011: Survey of instrument grading assessments of beef carcass characteristics

The instrument grading assessments for the 2011 National Beef Quality Audit evaluated seasonal trends of beef carcass quality and yield attributes over the course of the year. One week of instrument grading data, HCW, gender, USDA quality grade (QG), and yield grade (YG) factors, were collected every other month (n = 2,427,074 carcasses) over a 13-mo period (November 2010 through November 2011) from 4 beef processing corporations, encompassing 17 federally inspected beef processing facilities, to create a "snapshot" of carcass quality and yield attributes and trends from carcasses representing approximately 8.5% of the U.S. fed steer and heifer population. Mean yield traits were YG (2.86), HCW (371.3 kg), fat thickness (1.19 cm.), and LM area (88.39 cm(2)). The YG distribution was YG 1, 15.7%; YG 2, 41.0%; YG 3, 33.8%; YG 4, 8.5%; and YG 5, 0.9%. Distribution of HCW was <272.2 kg, 1.6%; 272.2 to 453.6 kg, 95.1%; and ≥453.6 kg, 3.3%. Monthly HCW means were November 2010, 381.3 kg; January 2011, 375.9 kg; March 2011, 366.2 kg; May 2011, 357.9 kg; July 2011, 372.54 kg; September 2011, 376.1 kg; and November 2011, 373.5 kg. The mean fat thickness for each month was November 2010, 1.30 cm; January 2011, 1.22 cm; March 2011, 1.17 cm; May 2011, 1.12 cm; July 2011, 1.19 cm; September 2011, 1.22 cm; and November 2011, 1.22 cm. The overall average marbling score was Small(49). The USDA QG distribution was Prime, 2.7%; Top Choice, 22.9%; Commodity Choice, 38.6%; and Select, 31.5%. Interestingly, from November to May, seasonal decreases (P < 0.001) in HCW and fat thicknesses were accompanied by increases (P < 0.001) in marbling. These data present the opportunity to further investigate the entire array of factors that determine the value of beef. Data sets using the online collection of electronic data will likely be more commonly used when evaluating the U.S. fed steer and heifer population in future studies.

National Beef Quality Audit-2011: In-plant survey of targeted carcass characteristics related to quality, quantity, value, and marketing of fed steers and heifers

The 2011 National Beef Quality Audit (NBQA-2011) assessed the current status of quality and consistency of fed steers and heifers. Beef carcasses (n = 9,802), representing approximately 10% of each production lot in 28 beef processing facilities, were selected randomly for the survey. Carcass evaluation for the cooler assessment of this study revealed the following traits and frequencies: sex classes of steer (63.5%), heifer (36.4%), cow (0.1%), and bullock (0.03%); dark cutters (3.2%); blood splash (0.3%); yellow fat (0.1%); calloused rib eye (0.05%); overall maturities of A (92.8%), B (6.0%), and C or greater (1.2%); estimated breed types of native (88.3%), dairy type (9.9%), and Bos indicus (1.8%); and country of origin of United States (97.7%), Mexico (1.8%), and Canada (0.5%). Certified or marketing program frequencies were age and source verified (10.7%), ≤A(40) (10.0%), Certified Angus Beef (9.3%), Top Choice (4.1%), natural (0.6%), and Non-Hormone-Treated Cattle (0.5%); no organic programs were observed. Mean USDA yield grade (YG) traits were USDA YG (2.9), HCW (374.0 kg), adjusted fat thickness (1.3 cm), LM area (88.8 cm2), and KPH (2.3%). Frequencies of USDA YG distributions were YG 1, 12.4%; YG 2, 41.0%; YG 3, 36.3%; YG 4, 8.6%; and YG 5, 1.6%. Mean USDA quality grade (QG) traits were USDA quality grade (Select(93)), marbling score (Small(40)), overall maturity (A(59)), lean maturity (A(54)), and skeletal maturity (A(62)). Frequencies of USDA QG distributions were Prime, 2.1%; Choice, 58.9%; Select, 32.6%; and Standard or less, 6.3%. Marbling score distribution was Slightly Abundant or greater, 2.3%; Moderate, 5.0%; Modest, 17.3%; Small, 39.7%; Slight, 34.6%; and Traces or less, 1.1%. Carcasses with QG of Select or greater and YG 3 or less represented 85.1% of the sample. This is the fifth benchmark study measuring targeted carcass characteristics, and information from this survey will continue to help drive progress in the beef industry. Results will be used in extension and educational programs as teaching tools to inform beef producers and industry professionals of the current state of the U.S. beef industry.

Helminth control using local resources in smallholder production systems of Asia

Practical helminth control in smallholder systems needs to match technical options with local knowledge, locally available animal and feed resources and the needs of both producers and consumers. Despite extensive research over many decades the uptake of new technology in these systems has been slow and limited to few farmers with access to good technical support. Investment by small holders is constrained by lack of regular market signals for livestock and livestock products. Examples of effective helminth control in cattle, buffalo, sheep, goat and pig systems show that effective control is possible using local resources and knowledge. Livestock systems in Asia are changing rapidly through industrialisation of production and consolidation of supply chains and retail markets, but smallholder systems, which are resilient and multipurpose, will remain important in rural areas and in peri-urban environments. They also provide a significant pathway for the poor to build assets and generate income. Helminth control in these systems will always vary greatly between farmers and systems and will need to be relatively simple and tailored to locally available resources. The public sector will continue to provide advice on appropriate genetics, to regulate drug importation, use and quality, and ensure novel helminth control options are investigated for local application and promotion to livestock producers. The private sector has the complementary role to develop clear market signals for livestock and livestock products, and make anthelmintics available in appropriate packages. Improved helminth control has the potential to increase the profitability and sustainability of all components of the livestock sector.

Efficacy of benzimidazole anthelmintics in goats and sheep in the Philippines using a larval development assay

The negative effects of nematodes in small ruminants can be reduced by use of dewormers but their effectiveness is increasingly limited by the emergence of anthelmintic resistance. The efficacy of benzimidazole (BZ) anthelmintics in the Philippines was estimated by an in vitro larval development assay using worm eggs recovered from faeces collected from goats and sheep. Two hundred and eighteen farms were selected to represent areas of the country with high goat and sheep populations and the full range of farm sizes, from smallholders with just a few animals to commercial and institutional farms with several hundred. Initial surveys of worm control advisers indicated that BZs have been in continuous widespread use for up to 20 years with little use of other chemical groups. A larval development assay (LDA: DrenchRite) was modified for use with BZs alone to allow up to five samples to be analysed on a single microtitre plate. The assay was validated by comparison with the faecal egg count reduction test (FECRT). The dominant nematode genera were Haemonchus and Trichostrongylus with small numbers of Oesophagostomum. The range of BZ efficacy estimated from the LDA results was 0-100% and the distribution of efficacy levels was continuous, with mean efficacy of 82 and 64% for goats and sheep, respectively. There were significant associations between efficacy and parameters measured to characterize the sampled farms: size of animal management group, FEC of sample, recent importation of stock and no access to common grazing were all correlated with decreased efficacy. Likewise, low efficacy was associated with reported frequency and number of years that BZ drenches had been used. The LDA was found to be highly suited to estimate efficacy in nematode populations from small farms where performance of a FECRT for even one chemical would be impractical. Using a larval development assay, we have demonstrated a wide efficacy range for BZs against nematodes from all sizes of goat and sheep farms in the tropics.

Enhancing immunity to nematode parasites in single-bearing Merino ewes through nutrition and genetic selection

The effectiveness of protein supplementation and genetic selection to enhance the resistance of periparturient Merino ewes to infection from gastrointestinal parasites was tested in a replicated grazing experiment. One hundred and twenty ewes from lines selected for increased resistance (R) to Haemonchus contortus or at random (C) were subjected to one of the three supplement groups that provided 0 or 250 g per day cottonseed meal for 5 weeks prior to, or for 6 weeks after the start of lambing. Faecal egg counts (FEC) of R ewes were consistently lower than those of C ewes but both groups exhibited a periparturient rise in FEC. Supplementation during the pre-partum period reduced FEC and increased ewe body weight gain. The benefits of pre-partum supplementation in reducing FEC continued to be apparent up to 10 weeks after supplementation ceased. There was a strong suggestion that the benefits to parasite resistance from protein supplementation were greatest in C ewes. Wool growth rates (15%) and birth weights (5%) were greater for C ewes but differences between the lines for lamb body weight had disappeared by day 97. The greatest benefit to resistance from protein supplementation was observed when ewes were experiencing a loss of maternal body weight. Conversely, no benefits to resistance were observed when ewes had moderate (78-107 g per day) rates of maternal weight gain. These results suggest that increased resistance as a result of protein supplementation is dependent on the prevailing supply and demand for scarce nutrients such as metabolisable protein (MP). Both genetic selection and protein nutrition are effective strategies to enhance host resistance to nematode infection during the periparturient period.

The intramammary inflammatory response of genetically resistant Merino ewes infected with Haemonchus contortus

The mammary glands of 103 pasture-reared non-lactating, non-pregnant Merino ewes were infused via the teat canal with antigens prepared from the nematode Haemonchus contortus, and the inflammatory response to infusion assessed by washing the gland of its contents after 24 h and 14 days. The ewes were of two genotypes: one with proven high levels of resistance to infection with the nematode H. contortus, the other random-bred animals with relative susceptibility to infection. On day 0 of a H. contortus infection, one gland of the subgroups of both genotypes was infused with the antigen preparation. At the same time, the other gland of the random-bred ewes was infused with sterile physiological saline. A third group of infected random-bred ewes was infused with only sterile physiological saline. Similar infusions were performed on other subgroups on days 12, 21 and 35 of infection, which was then terminated with anthelmintic. A fourth group of uninfected random-bred control ewes was given both infusions 35 days after the other groups were infected. Sheep of the resistant genotype had lower worm egg counts and smaller reductions in blood packed cell volumes from day 21 of infection. Infusion of antigen had no effect on the course of infection and no effect on the response of the other gland, which had been infused with saline alone. The dominant leukocyte response from the antigen-infused gland was eosinophilia. On all days of infusion, and after both 24 h and 14 days, eosinophil counts from the resistant genotype were higher than those from their random-bred counterparts. The sheep mammary gland provides a source of eosinophils whose number is related to host genotype and stage of infection and may provide a model for the investigation of cellular responses in mucosal immunity to nematode infections.

Long-term effects of short-term provision of protein-enriched diets on resistance to nematode infection, and live-weight gain and wool growth in sheep

Weaner sheep that had been hand-fed on diets containing increasing concentrations of protein for a 9-week period (when uninfected, or infected with Haemonchus contortus) were studied during the next 69 weeks when put on to pasture as a single, unsupplemented flock. During the 9-week period, groups of 12 sheep (six infected, six uninfected) were offered one of five iso-energetic (9.0 MJ kg(-1)) diets containing 10, 13, 16, 19 or 22% crude protein. All sheep were treated with anthelmintic at the end of the 9 weeks and then put out to pasture for 69 weeks, where they were all subject to the same environmental variables including nematode larval challenge. During the grazing period, animals that had previously received the higher protein diets consistently had higher live-weight gain and wool production, higher antibody responses to both H. contortus and Trichostrongylus colubriformis antigenic challenge in vitro, and lower faecal nematode egg counts than did the lambs previously offered the lower protein diets. Faecal egg counts of the grazing sheep that had been artificially infected with H. contortus while being hand-fed were similar to those of the uninfected sheep and there was no interaction between previous infection and dietary protein concentration. We conclude that short periods of enhanced post-weaning nutrition can have long-term and perhaps life-long effects on production.

Workshop on irradiated larval vaccines

The development of anthelmintic resistance in gastrointestinal parasites of sheep and goats has meant that there is an urgent need for non-chemical control of these parasites. In order to investigate a potential alternative method of control, a workshop on irradiated larval vaccines (ILV) was held in conjunction with the Second International Conference on Novel Approaches to the Control of Helminth Parasites of Livestock. The objectives of the workshop were to: (1) Review knowledge of irradiated helminth vaccines through the presentation of invited and contributed papers. (2) Identify opportunities for an ILV and in which host/parasite/production systems. (3) Determine what are the gaps in knowledge required to produce and apply an ILV. The workshop concluded that ILVs could be useful as research tools in the further definition of immune responses to parasites and in stimulating the immune response in young sheep and goats to facilitate the estimating of heritability of faecal egg counts. Although the workshop identified some problems associated with a live attenuated vaccine, an ILV could be a useful control measure in the production systems identified by the workshop. Before an ILV could be used on farms, additional research is required into the period of protection afforded by an ILV especially under field conditions. The efficacy of an ILV could be improved by interaction between host genotype and nutritional status and is deserving of further investigation.

Protein supplementation improves the performance of parasitised sheep fed a straw-based diet

A study was made of the benefits of protein supplementation for parasitised and non-parasitised lambs. Sixty, 5-month-old crossbred wether lambs were placed in individual pens indoors for 9 weeks. Half of the animals were experimentally dosed with 1500 Haemonchus contortus larvae per head per week and were fed ad libitum and the other half were worm-free, pair-fed controls. Diets were formulated to be iso-energetic (9.0 MJ of calculated metabolisable energy per kg dry matter) with five levels of protein (10, 13, 16, 19 and 22% crude protein). These diets were based on oaten chaff, with barley, cotton-seed meal, urea and mineral mix (except for the 22% crude protein diet which did not contain barley). Dietary crude protein content increased live-weight gain, feed intake, rumen fluid ammonia-N, packed cell volume, eosinophil counts and antibody responses to H. contortus L3 antigen and decreased faecal worm egg counts significantly. Infection did not significantly affect packed cell volume of animals on diets with 16, 19 and 22% crude protein content. We conclude that extra dietary protein can prevent the adverse effects of H. contortus infection on animal production.

Breeding for disease resistance in Merino sheep in Australia

Breeding for disease resistance in Merino sheep in Australia has attracted considerable research and development attention. Increased labour costs, the reduced efficacy of common anthelmintics and insecticides, consumer demand for products which are free of chemicals and the poor prognosis of alternative long-term control strategies are all forcing sheep breeders to contemplate the best animal health options available, including selective breeding for resistance. The three major diseases which affect sheep production include gastrointestinal nematode parasites, flystrike (cutaneous myiasis) and footrot. Genetic improvement has been shown to be feasible in all these diseases, possibly with little adverse effect on genetic progress in other production traits. Programmes for resistance to internal parasites to be included in practical breeding programmes are now in progress. This paper deals with the incentives for focusing on the three major diseases in Merino sheep, the potential sources of genetic variation, and the means to exploit these sources of variation. The authors also highlight gains and benefits achieved in experimental selection flocks, and the difficulties and options available for commercial breeders.

Receptors for the chemoattractants C5a and IL-8 are clustered on the surface of human neutrophils

We have used high-resolution field emission scanning electron microscopy with backscatter electron imaging to detect immunogold-labeled C5a and interleukin-8 (IL-8) receptors on human blood neutrophils. The receptors were labeled with receptor-specific antibodies in combination with secondary antibody conjugated to immunogold. When neutrophils were isolated in a "nonactivated" state, both of these receptor populations were expressed primarily in clusters on nonprojecting domains of the cell membrane. When these cells were double labeled for C5a and IL-8 receptors, intermixing of these receptor species in a common cluster was not found. When neutrophils were isolated in an "activated" state, by mixing the blood with N-formylmethionyl-leucyl-phenylalanine, the cells were seen to be elongated and ruffled at their anterior pole, but the C5a receptors did not disperse or redistribute on the surface of the peptide-activated cells. Analysis of the distribution of human C5a receptors expressed by transfected mouse L-cell fibroblasts showed the C5a receptors to be clustered, but expressed on nonprojecting and projecting domains of the cell surface. These observations provide new information on the topographical expression of leukocyte receptors involved in directing cell migration.

The use of genetically resistant sheep to control nematode parasitism

Research in the last 20 years has firmly established that it is possible to exploit genetic variation in resistance to the nematode parasites of sheep by selection. Selected sheep are more resistant to infection and commercial application of this research is under way in both Australia and in New Zealand. Not all the consequences of these breeding programs have been established, particularly long-term consequences for productivity and the interaction with other control measures, but the technology is available in the public domain with no commercial restrictions. Faecal worm egg count remains the most effective way of selecting sheep although many alternatives, such as DNA markers, host antibody and parasite antigen assays are being developed for use as selection criteria. Strategic nutritional supplementation is an immediate candidate for inclusion in worm control programs and although nematode vaccines remain elusive, it is likely that some will be field-tested in the next few years. For both of these approaches, nutritional and immunological, it is critical that the response of selected genotypes are assessed under commercial conditions and as components of worm control programs. There is evidence to support the possibility that selected sheep will be more responsive to vaccination while the long-term interaction between the effect of strategic nutritional supplements and resistant genotypes needs to be investigated.

Rapid measurement of modified oligonucleotide levels in plasma samples with a fluorophore specific for single-stranded DNA

Animal studies of therapeutic oligonucleotides require measurement of circulating levels of oligonucleotides by multistep, time-consuming methods. In contrast, addition of a single-stranded DNA binding fluorophore, OliGreen, to oligonucleotides in plasma samples allowed rapid quantitation. Dose-response curves were measured for five different oligonucleotide analogs added to plasma or serum. Phosphorothioate or 3'-amino phosphodiester oligodeoxynucleotides in calf serum reliably exhibited linear, dose-dependent fluorescence at 15-500 nM. The assay was equally sensitive in human and mouse plasma, with a heterogeneous variety of sequences. Oligonucleotides shorter than 10 nucleotides yielded substantially reduced fluorescence. In contrast, 2'-O-methyl oligoribonucleotides, DNA methylphosphonates, and peptide nucleic acids demonstrated little or no fluorescence with OliGreen. Following intravenous injection of a phosphorothioate pentadecamer into mice, fluorescence measurements of plasma phosphorothioate levels displayed a dose-dependent, biexponential decline over a 90 min period. Chronic infusion at 2.5 nmol/hour into mice yielded plasma oligonucleotide values equivalent to 0.1 microM, a value reflecting the contributions of intact and partially degraded strands. Tumor-bearing mouse plasma evidenced high fluorescence values in the absence of oligonucleotide administration, presumably because of elevated intrinsic plasma DNA fragments. Although limited in its ability to differentiate intact from partially degraded strands, OliGreen fluorescence provides a simple, rapid, and sensitive method for measuring circulating levels of phosphorothioate or phosphodiester oligonucleotides in healthy animals or humans.

Transformed and immortalized cellular uptake of oligodeoxynucleoside phosphorothioates, 3'-alkylamino oligodeoxynucleotides, 2'-O-methyl oligoribonucleotides, oligodeoxynucleoside methylphosphonates, and peptide nucleic acids

Direct quantitative comparisons of cellular uptake across a wide variety of analogs and cell types are necessary for the design of oligonucleotide diagnostic and therapeutic applications. This work reports quantitative cellular uptake and nuclear localization of [14C]oligodeoxynucleoside phosphorothioates (PS), 3'-alkylamino oligodeoxynucleoside phosphodiesters (PO-NH2), 2'-O-methyl oligoribonucleoside phosphodiesters (2OM), peptide nucleic acids (PNA), and oligodeoxynucleoside methylphosphonates (MP) in several transformed or immortalized cell lines. All analogs demonstrated active cellular uptake in that intracellular concentrations greatly exceeded the extracellular 1 microM concentration within 1-3 hr. However, by 9-24 hr, cellular accumulations of PS exceeded those of PO-NH2 and 2OM by 3- to 5-fold, PNA by 6- to 7-fold, and MP by 8- to 10-fold. Similar results were observed in two transformed cell lines, HL-60 leukocytes and H-ras transformed fibroblasts, using three different heterogeneous sequences. H-ras and IGF-1R transformed fibroblasts had a 2- to 5-fold higher uptake of all analogs than non-transformed immortalized fibroblasts. Nuclear levels of the PO-NH2, PS, and MP analogs were approximately 25% of total cellular uptake, while nuclear percentages of 2OM and PNA were less than 20%, suggesting some differences in nuclear localization among the analogs. These observations provide a direct quantitative comparison of cellular uptake as a function of oligonucleotide modification, and imply that transformation enhances cellular uptake. From the perspective of therapy and diagnosis, clear trade-offs were apparent between efficiency of uptake on the one hand, and nuclease resistance and hybridization strength on the other.

Some relationships between age, immune responsiveness and resistance to parasites in ruminants

In the Australian livestock industries, susceptibility to infectious diseases is generally greater in young than in mature ruminants. The increased susceptibility is manifest as respiratory and intestinal infections (viral and bacterial) of calves, as well as fleece rot, flystrike and, especially, gastrointestinal parasitic infestations of young sheep. Lower resistance to infectious disease in young ruminants appears to be due largely to immunological hyporesponsiveness, and is not simply a consequence of their not having been exposed sufficiently to pathogens to develop active immunity. Young sheep have significantly lower proportions of CD4+ and CD8+ lymphocytes, but similar proportions of T19+ and B lymphocytes in blood, lymph and skin compared with mature sheep. Blood lymphocytes from young sheep produce less interferon-gamma in culture and young sheep invariably mount smaller antibody responses than do mature animals. Taken together, these findings begin to explain why young ruminants are more susceptible to infectious diseases in general, and to gastrointestinal parasites in particular, when compared to mature animals. Haematological markers of disease resistance, the prevalence of non-selected diseases and immune responses to vaccination were examined in the internal parasite-resistance flocks in Armidale NSW and the fleece rot/flystrike selection flocks at Trangie NSW. Any programme that seeks to improve resistance to parasitic or any other disease should have the capacity to make contemporary measurements of resistance to other diseases which are important in, or threaten, the production system.

Incidence, source, and nature of complaints received in a large, urban emergency medical services system

OBJECTIVE

To document the incidence, source, and reasons for all complaints received by a large municipal emergency medical services (EMS) program.

METHODS

A retrospective review of all complaints received during three consecutive years (1990-1992) in a centralized EMS system serving a large municipality (population 2 million). All cases were categorized by year, source, and nature of the complaint.

RESULTS

In the three study years, EMS responded to 416,892 incidents with nearly a half-million patient contacts. Concurrently, 371 complaints were received (incidence of 1.12 per thousand); 132 in 1990, 129 in 1991, and 110 in 1992. Most complaints involved either: 1) allegations of "rude or unprofessional conduct" (34%), 2) "didn't take patient to the hospital" (19%), or 3) "problems with medical treatment" (13%). Only 1.6% (n = 6) were response-time complaints. Other complaints included "lost/damaged property," "taken to the wrong hospital," "inappropriate billing," and "poor driving habits." The most common sources were patient's families (39%) and the patients themselves (30%). Only 7.8% were from health care providers.

CONCLUSION

Reviews of complaints provide information regarding EMS system performance and reveal targets for quality improvement. For the EMS system examined, this study suggests a future training focus on interpersonal skills and heightened sensitivities, not only toward patients, but also toward bystanders and family members.

Antibody-containing cells in the abomasal mucosa of sheep with genetic resistance to Haemonchus contortus

The frequency distribution of parasite-specific antibody-containing cells (ACC) and total immunoglobulin-containing cells (ICC) in the abomasal mucosa was examined in genetically resistant and random-bred sheep, following infection with Haemonchus contortus, to determine whether the two genotypes differed in the development of a local immune response. Immunofluorescence staining was used to detect ACC and ICC of IgA, IgG1, IgG2 and IgM classes. No ACC were found in the abomasum of any of the sheep before infection. ACC were first detected in the abomasal mucosa of both the resistant and susceptible sheep seven days after infection, reached a peak level on day 21 and then declined. At all observation times, the majority of ACC in both genotypes were of the IgA isotype, followed by IgG1 and IgM. The IgG2-ACC response was negligible compared with the IgA and IgG1 response. The comparison of genotypes showed that the resistant sheep had significantly more IgA-ACC on days 14, 21, 28 and 35, and significantly more IgG1-ACC than random-bred sheep on days 14, 21 and 28. The numbers of IgG2- and IgM-ACC did not differ between the genotypes. The abomasal mucosa of the resistant sheep was also found to have significantly more ICC than the mucosa of random-bred sheep; IgA-ICC predominated at all the observation times followed by IgG1 and IgM. These results suggest that IgA and IgG1 antibodies, produced locally in response to infection, may play a role in mediating genetic resistance to haemonchosis in sheep.

A search for associations between major histocompatibility complex restriction fragment length polymorphism bands and resistance to Haemonchus contortus infection in sheep

Polymorphic bands were detected within the DQB and DRB regions of the ovine major histocompatibility complex by probing TaqI digested DNA from three large sheep half-sib families derived from a highly resistant ram. All animals were phenotypically assessed for Haemonchus contortus resistance by faecal egg counts and associations with RFLP bands and haplotypes were estimated using mixed model, best linear unbiased prediction statistical methods. Although the highly resistant sire was homozygous at the MHC, no significant associations were found between any band or haplotype and faecal egg count.

Host genes, parasites and parasitic infections

Resistance to infection of mammalian hosts by parasites is under genetic control at many different levels: between species, between races, breeds and lines of single species and between individuals. These genetic effects have been described in many host-parasite systems. Here we review the interaction between three elements: host genes, parasites and the environment in which parasitic infections develop. Already livestock industries exploit genetic variation between breeds, particularly for the control of trypanosomiasis and tick infestation in cattle. In most populations, and to many diseases, resistance is heritable and selective breeding for resistance in commercial livestock species has been successful experimentally. Attempts at utilizing genetic variation are placed in the broad context of the coevolution of host and parasite, the limited knowledge we have of the mode of action of resistance genes and our ability to use genetic information to predict resistance to parasites.

Isotype-specific antibody responses to Haemonchus contortus in genetically resistant sheep

The kinetics of anti-Haemonchus antibody responses in serum and faecal extracts of pasture-reared, genetically resistant and random-bred sheep infected with Haemonchus contortus were examined using an isotype-specific ELISA. Anti-Haemonchus antibodies of IgA, IgG1, IgG2 and IgM isotypes were detected in serum and faecal extracts of both resistant and random-bred sheep after challenge infection. Serum IgG1 and IgA levels in resistant sheep were significantly higher than in random-bred sheep between 10 and 31 days after infection. However, there were no differences in IgG2 and IgM antibody responses between the two genotypes. Faecal antibody responses to H. contortus showed a clear genetic effect with resistant sheep exhibiting higher IgA levels throughout infection and higher IgG1 levels between 24 and 31 days after infection. Furthermore, serum IgG1 and IgA, and faecal IgA responses were negatively correlated with faecal egg counts in both genotypes on 17, 24 and 31 days after infection. Together, these results are taken to indicate that anti-parasite IgA and IgG1 antibodies may play an important role in genetically determined resistance of sheep to haemonchosis.

Antisense DNA inhibition of tumor growth induced by c-Ha-ras oncogene in nude mice

Antisense DNA has shown an ability to target specific oncogene transcripts and inhibit their expression in cells, but the degree to which sustained treatment can suppress total levels of an oncogenic product and alter tumorigenesis in vivo remains to be determined. In this study, NIH-3T3 cells transformed by the activated c-Ha-ras oncogene from T24 human bladder cancer cells were treated for 3 consecutive days in vitro with an antisense DNA pentadecamer complementary to a target in the 5'-flanking region of the c-Ha-ras RNA transcript. Following antisense DNA treatment, a portion of the cells was lysed for measurement of RAS p21 while the remaining cells were evaluated for tumorigeneity by injection s.c. into athymic nude mice at a dose of 5 x 10(5) cells/mouse. The 3 days of treatment with the anti-c-Ha-ras DNA reduced RAS p21 cellular levels by more than 90% while a nonspecific control DNA reduced p21 levels by approximately 20%. Tumor growth of cells treated with anti-c-Ha-ras DNA was significantly reduced for up to 14 days following the end of treatment and implantation into the mice whereas the nonspecific control DNA had no significant effect. These effects on tumor growth were evident in two different strains of nude mice and in both males and females. It is suggested that the pronounced decrease in RAS p21 levels produced by anti-c-Ha-ras DNA resulted in a reversal of the transformed phenotype, and it is this reversal which accounts for the prolonged inhibition of tumorigenesis following antisense DNA treatment.

Parasitological and immunological responses of genetically resistant Merino sheep on pastures contaminated with parasitic nematodes

One hundred and twenty lambs were grazed continuously from weaning until 9 months of age on 12 plots contaminated with larvae of three nematode species (Haemonchus contortus, Trichostrongylus colubriformis and Ostertagia circumcincta). The lambs were sired by either a genetically resistant ram or susceptible rams (determined by the response of previous progeny to artificial H. contortus infection). Half the resistant and half the susceptible lambs were given strategic anthelmintic treatment and the remainder remained untreated. Faecal egg counts and blood packed cell volume were measured frequently in all animals. One and 5 months after weaning, two lambs from each plot were slaughtered, and worm burdens and larval establishment rates of the three species of nematode were estimated. At the second slaughter, leukotriene levels and larval migration inhibitory (LMI) activity were measured in mucus collected from the small intestine. The dominant species in all faecal samples and the gastrointestinal tract was T. colubriformis. Lambs of the resistant genotype had lower faecal worm egg counts, lower worm burdens and higher levels of resistance to larval establishment. There were no differences in larval migration inhibition (LMI) activity, but resistant lambs had higher levels of the leukotriene LTC4/D4/E4. Further, the resistant genotype, identified on responsiveness to artificial infections with H. contortus, was more resistant to infections of three important species acquired naturally from contaminated pastures. All these genetic differences were maintained while the lambs were subject to strategic anthelmintic treatment.

The effect of Haemonchus contortus on liveweight gain and wool growth in young merino sheep

Results of three crossover experiments on a total of 1078 Merino lambs were used to estimate the effect of a single infection of 11 000 Haernonchus contortus larvae on liveweight gain, clean wool growth and wool fineness. Estimates were obtained by direct comparison of six groups of infected and matched uninfected iambs under field conditions. Infections were terminated after 5 weeks, at which stage some mortality had occurred and haematocrits had in five out of six cases declined to less than 24%. Over an 8-9 week period, beginning at the time of infection, liveweight gains of infected lambs were reduced by on average 1.29 kg (range 0.83-1.71 kg) amounting to 38% (12-64%) of liveweight gain in uninfected controls. The detrimental effect of infection was most severe towards the end of the infection period. There was a lag phase of 3-6 weeks between larval administration and the onset of wool growth depression. The reduction of wool growth persisted for at least 14 weeks after termination of infection. The size of this reduction was very variable. Over a 4 month post-infection period, reductions ranged from 11 to 97 g clean wool (mean 46 g) or 1.4 to 157% (mean 6.8%) of clean wool grown by uninfected lambs. Estimates of reduction of fibre diameter over the same period ranged from 0.39 to 0.79 8m (mean 0.57 8m).

The effect of immunosuppression with dexamethasone on Haemonchus contortus infections in genetically resistant merino sheep

The effect of immunosuppression with the glucocorticosteroid, dexamethasone, on the susceptibility to Haemonchus contortus infection of a highly resistant Merino genotype was investigated. Higher faecal egg counts, larger worm burdens and heavier worms were recorded in immunosuppressed wethers. The characteristic globule leucocyte infiltrate in the abomasum of resistant wethers (12-month-old castrated males) was absent in immunosuppressed animals. Treatment with dexamethasone abolished differences between resistant and susceptible genotypes in faecal egg counts, worm weights, thymus weights and globule leucocyte responses to infection with H. contortus. These results suggest that an immunological basis underlies the high level of resistance to infection in the resistant genotype.

Genetic resistance to haemonchosis in sheep

Parasitic nematodes cause huge economic losses to the domestic livestock industry. Control requires skilled farm management and heavy use of anthelmintics, but breeding for resistant animals has long been held a possibility. For about 20 years after World War ll, the genetics of association between sheep breeds and Haemonchus contortus - the main parasite of importance in sheep - was studied in the USA and Europe. Since the early 1970s, however, such studies have received greater emphasis in Australia, where anthelmintic resistance has become widespread. In this article, Douglas Gray discusses the background to breeding programmes for resistance to hoemonchosis - paying homage to the 'Golden Ram', a Merino believed to have carried a single major gene for immunological resistance to Haemonchus and Trichostrongylus.

Feline polymorphonuclear leukocytes respond chemotactically to leukotriene B4 and activated serum but not to F-Met-Leu-Phe

The chemotactic response of feline polymorphonuclear leukocytes (PMNs) to three types of chemoattractants was studied. Feline PMNs responded to leukotriene B4 as well as to agarose-activated autologous and homologous serum. However, no response was obtained to N-formylmethionylleucylphenylalanine (FMLP), and four similar peptides that activate the FMLP receptor (N-formylnorleucylleucylphenylalanine, N-formylmethionylphenylalanine, methionylleucylphenylalanine, and pepstatin). Thus, feline PMNs are similar to equine, porcine, bovine and canine PMNs which also do not respond chemotactically to these peptides.

The role of cyclooxygenase and lipoxygenase pathways in the adhesive interaction between bovine polymorphonuclear leukocytes and bovine endothelial cells

The effects of arachidonic acid metabolites, analogues and cyclooxygenase/lipoxygenase inhibitors were tested on an "in vitro" bovine model of endothelial cell (EC)-polymorphonuclear leukocyte (PMN) adhesion. Arachidonic acid blocked adhesion at 10(-5)M, a dose which also induced aggregation of PMN. Lower doses did not affect either EC-PMN adhesion or PMN aggregation. Various cyclooxygenase pathway metabolites were inactive in the EC-PMN adhesion assay, with the exception of prostaglandin A2 and prostaglandin B2 which significantly suppressed adhesion at 10(-5)M. Of the synthetic analogs tested, 6 alpha-carbaprostacyclin I2, (5Z)-9 beta-ethynyl-calcium salt (U-64,567E) was inhibitory at 10(-5)M. The cyclooxygenase inhibitors acetylsalicylic acid, indomethacin and ibuprofen were inactive. Products of the lipoxygenase pathways, leukotriene B4 (LTB4), 5-hydroxyeicosatetraenoic acid (5-HETE) and 15-hydroperoxyeicosatetraenoic acid (15-HPETE) exhibited variable inhibitory activity at 10(-5)M only. Paradoxical effects were observed with the putative lipoxygenase inhibitors 4,7,10,13-eicosatetraynoic acid (4,7,10,13 ETYA), 5,8,11,14-eicosatetraynoic acid (5,8,11,14 ETYA) and nordihydroguairetic acid (NDGA), which also suppressed EC-PMN adhesion at 10(-5)M. The dual cyclooxygenase-lipoxygenase inhibitor, BW755C was inactive. Bovine PMNs did not respond chemotactically to LTB4 although they were able to synthesize the 5-lipoxygenase products LTB4 and 5-HETE.

Countergradients of nonchemotactic ligands for N-formylmethionylleucylphenylalanine (FMLP) receptors promote FMLP-induced chemotaxis

Using the under-agarose chemotaxis assay, addition of compounds known to inhibit chemotaxis of leukocytes toward N-f-Met-Leu-Phe (FMLP) was made to the first well in a line of three wells, leukocytes to the middle well, and a slight excess of FMLP to the third well. The compounds included rifampin, fusidic acid, carbobenzoxy Phe-Met, phenylbutazone, sulfinpyrazone, sulfasalazine, and sulfapyridine. The countergradients created in this system markedly stimulated, not inhibited, locomotion toward FMLP. These results, based on functional responses, confirm data using radiolabeled FMLP and support the hypothesis that these compounds are nonchemotactic ligands for FMLP receptors.

Antibiotic binding to human polymorphonuclear neutrophils, mouse leukemia L1210 cells and mouse thymocytes

This report describes a system in which antibiotics could be compared for binding to different mammalian cells. These included functional phagocytes (human polymorphonuclear neutrophils; PMNs), non-phagocytic lymphocytes (mouse thymocytes), and non-functional leukocytes (mouse leukemia L1210 cells). When antibiotics bound to PMNs, they bound about the same to L1210 cells but much less to thymocytes. Combining these data with previous data, the ranking of cells that bound the greatest amount of antibiotics was: PMNs = L1210 cells = blood mononuclear leukocytes greater than thymocytes greater than erythrocytes. Thus, antibiotics bind differentially and not indiscriminately to mammalian cells.

A simple system for studying antibiotic binding to leukocytes

Studies on the interaction between antibiotics and polymorphonuclear leukocytes (PMLs) usually require the availability of radiolabeled antibiotic, that the antibiotic kill intraleukocyte pathogens, or that the antibiotic affect some function of the leukocyte. The system described here does not have the requirements above but depends instead upon anti-staphylococci activity. The key features of the system are that, following incubation, extracellular antibiotic was removed from PMLs by centrifugation, contact between Staphylococcus aureus 502A and the phagocyte-antibiotic complex was assured by centrifugation at 4 degrees C in 96 well tissue culture dishes, phagocytosis was induced by incubation at 37 degrees C, and assessment of surviving bacteria was accomplished by collecting [3H]thymidine labeled bacteria using a cell harvester. Antibiotics that were active in this system included naphthalenic ansamycins (rifamycins and streptovaricins ), lincosaminides ( clindamycins and pirlimycins ), coumarins (novobiocin), erythromycin, tetracycline, tyrocidine and paulomycin .

Rifampin affects polymorphonuclear leukocyte interactions with bacterial and synthetic chemotaxins but not interactions with serum-derived chemotaxins

Three independent experimental approaches support the hypothesis that rifampin competes for receptors on polymorphonuclear leukocytes (PMLs) with small peptide chemoattractants, e.g., N-formylmethionylleucylphenylalanine (FMLP), but not with serum-derived chemoattractants (C5a). First, rifampin inhibited chemotaxis induced with FMLP but reversed the immobilization of PMLs that occurred at high FMLP concentrations. Second, rifampin competed with radiolabeled FMLP for binding sites on PMLs and displaced already-bound radiolabeled FMLP. Third, rifampin blocked and reversed the bipolar shape changes induced in PMLs by FMLP. These effects occurred at concentrations attained during rifampin therapy and were not due to rifampin toxicity. In contrast, no effect of rifampin was observed on serum-derived chemoattractants (C5a) in any of the three systems. The evidence suggests, therefore, that rifampin is a ligand for FMLP-type receptors on PMLs.

MIC values do not predict the intraphagocytic killing of Staphylococcus aureus by naphthalenic ansamycins

Ten naphthalenic ansamycins were compared for their ability to kill extracellular or phagocytosed Staphylococcus aureus 502A. These included rifamycins, streptovaricins and tolypomycin Y. Although the compounds differed markedly in killing extracellular S. aureus, there was surprisingly little difference between them in assisting human leukocytes to kill phagocytosed S. aureus. In fact, when compared to rifampin, some ansamycins that were less effective in killing extracellular bacteria were more effective in killing phagocytosed bacteria. These data, together with an analysis of structure and activity, suggested that a specific transport mechanism might be involved. First considered was a vitamin K transport mechanism. Indeed warfarin, a vitamin K antagonist, blocked the ability of rifampin to kill phagocytosed S. aureus, as did the coumarins, novobiocin and coumarin-3-carboxylic acid. However, direct evidence for a vitamin K transport mechanism could not be obtained using vitamin K preparations. The fused phenolic, bicyclic system common to all of these ansamycins was tentatively considered to be the portion necessary for phagocyte penetration.

Hormonal changes and sexual function in aging men

A cross-sectional study on 220 men, aged 41-93 yr, was conducted to determine whether age-related changes in circulating pituitary and gonadal hormone levels are related to quantitatively assessed changes in sexuality over this age span. The conclusion of most previous studies, that total and free plasma testosterone (T) levels decline with advancing age as gonadotropins increase, was corroborated. These changes were found to roughly parallel a decline in sexual function affecting the level of sexual activity, libido, and potency measures. PRL and estradiol did not change with age, and the age-related decline in free T was greater than that in total T. Decreases in free T and increases in LH manifested significant, but small, correlations with sexual hypofunction. Behavioral variables were also clearly related to LH and to the ratio of free T to LH and estradiol. The data also suggested that aging and hormonal changes were more strongly related to sexual activity and nocturnal erections that to libido (enjoyment, drive, and thoughts). Partial correlation procedures demonstrated that diseases and drugs were not responsible for the hormone-behavior relationships. Declining androgen levels, reduced sexual activity, and decreased sexual interest thus appear to be related sequelae of the aging process in men. Hormonal factors do not completely account for age-related changes in sexuality, although the full explanation of these changes must include a consideration of hormonal factors.

Suppression of primary and secondary antibody responses and inhibition of antigen priming during Babesia microti infections in mice

The antibody response to sheep red blood cells (SRBC) has been measured in C57Bl mice infected with the intra-erythrocytic piroplasm Babesia microti. The primary antibody response is severely reduced or abolished when antigen is administered at the time of maximum parasitaemia. The secondary antibody response of infected mice, which had been primed with SRBC, is reduced but retains the characteristics of a secondary response. Mice injected with SRBC at maximum parasitaemia failed to become primed to that antigen: these mice gave a primary antibody response to a second injection of SRBC given after the infection had become sub-patent. B. microti, therefore, can completely prevent the induction of memory, but only partially inhibit the expression of memory.

Chemotactic requirements of bovine leukocytes

A system was described for studying bovine leukotaxis. Chemotaxis was readily observed toward bovine serum activated by zymosan of agarose. However, bacterial culture filtrates and peptides, which were potent chemotaxins for leukocytes from other species, failed to affect bovine leukotaxis. Using conditions suitable for studying binding to leukocytes from other species, specific binding of a radiolabeled chemotactic peptide to bovine leukocytes was not apparent. These data indicate that bovine leukocytes have chemotactic requirements distinct from those of other species.

The use of Erlangen diamidine 98/202 in relapsing Trypanosoma brucei infections in mice

Mice infected with T. brucei GVR 23/1 or T. brucei GVR 35/1 for 21 days were treated with the Erlangen diamidine 98/202 (6-amidino-2-[4' amidino-phenyl] thionaphthene-dilacate) at either 5 mg/kg or 35 mg/kg. At both these dose levels the parasites were initially cleared from the circulation although the infections eventually relapsed due to reinvasion from the central nervous system. If the 98/202 therapy is followed by treatment with 5-nitroimidazole only a small number of mice are permanently cured. Adverse reactions, especially at the 35 mg/kg dose level, were noted in one experiment. The Erlangen diamidine given to infected mice three days after infection was able to permanently cure both Trypanosoma brucei stabilates.

Relapse of monomorphic and pleomorphic Trypanosoma brucei infections in the mouse after chemotherapy

Infections in mice were initiated with trypomastigotes from two lines of Trypanosoma brucei derived from the same primary isolated. Infections with one line were initiated by inoculation of metacyclic trypomastigotes from infected tsetse flies and the resulting infections were pleomorphic. The other line had been passaged 32 times in rodents and inoculation of bloodstream trypomastigotes gave rise to monomorphic infections. In both infections there were high levels of parasitaemia until death up to 4 weeks later if the infection was untreated. It was shown that after chemotherapy with 40 mg/kg diminazene aceturate (Berenil) relapses occurred in both types of infection after an aparasitaemic period of 2--3 weeks. Further, it was shown that 3 days after chemotherapy, brain tissue but neither spleen, liver nor blood was capable of transferring infection to normal recipient mice. There were two major differences in the response of the two infections to chemotherapy. First, treatment of the pleomorphic infection as soon as day 6 after infection resulted in a subsequent relapse while the monomorphic infection had to be at least 12 days old at the time of treatment before occurred. Second, following treatment of the pleomorphic, but not of the monomorphic infection there was an early transient recrudescence of low numbers of trypanosomes which were found to be non-infective to recipient mice. The early transient relapse was followed by a further aparasitaemic period and then the late continuous relapse characterised by large numbers of infective trypanosomes.

The possible use of Trypanosoma musculi infection in mice as a screening test for potential Trypanosoma cruzi-active drugs

The ability of a range of trypanocidal drugs, including a number known to be active in Trypanosoma cruzi infections were tested against Trypanosoma musculi infections in the mouse. The ability of these drugs, particularly in their ability to eliminate the "cryptic phase" of T. musculi infections remaining in the kidneys, was investigated and their activity against this phase of T. musculi largely paralleled their known activity against T. cruzi infections. It is suggested that this could be used as a preliminary screening test for potential T. cruzi-active drugs.

Dissociation of adrenal corticosteroid production from ACTH in water-restricted female rats

These experiments were undertaken to investigate the mechanism whereby a precipitous drop in plasma corticosterone concentration is brought about following drinking in rats on a restricted water schedule. No alteration in adrenocorticotrophic hormone (ACTH) output was found, nor was catabolism of corticosterone sufficient to account for the drop. It is concluded that corticosterone level is controlled under these conditions by a mechanism independent of ACTH concentration.

Use of sorbitol in the cryopreservation of babesia

Blood collected from mice infected with Babesia microti was frozen at two different rates to -196 degrees C using 19 per cent (w/v) glycerol as cryoprotectant. Survival of the parasites was measured by recording the parasitaemias of mice inoculated with thawed blood. Parasite survival was increased by using a solution of sorbitol in saline rather than Hanks' balanced salt solution as the diluent for the glycerol and for washing the recovered blood.