Age-related changes in muscle architecture and metabolism in humans: The likely contribution of physical inactivity to age-related functional decline.

In the United Kingdom (UK), it is projected that by 2035 people aged >65 years will make up 23 % of the population, with those aged >85 years accounting for 5% of the total population. Ageing is associated with progressive changes in muscle metabolism and a decline in functional capacity, leading to a loss of independence. Muscle metabolic changes associated with ageing have been linked to alterations in muscle architecture and declines in muscle mass and insulin sensitivity. However, the biological features often attributed to muscle ageing are also seen in controlled studies of physical inactivity (e.g. reduced step-count and bed-rest), and it is currently unclear how many of these ageing features are due to ageing per se or sedentarism. This is particularly relevant at a time of home confinements reducing physical activity levels during the Covid-19 pandemic. Current knowledge gaps include the relative contribution that physical inactivity plays in the development of many of the negative features associated with muscle decline in older age. Similarly, data demonstrating positive effects of government recommended physical activity guidelines on muscle health are largely non-existent. It is imperative therefore that research examining interactions between ageing, physical activity and muscle mass and metabolic health is prioritised so that it can inform on the "normal" muscle ageing process and on strategies for improving health span and well-being. This review will focus on important changes in muscle architecture and metabolism that accompany ageing and highlight the likely contribution of physical inactivity to these changes.

Development and preliminary assessment of a polyclonal antibody-based enzyme immunoassay for the detection of Tritrichomonas foetus antigen in breeding cattle.

More sensitive tests are required for the diagnosis of Tritrichomonas foetus infection in cattle and an antigen-detecting enzyme immunoassay (EIA) has been applied to this purpose. An affinity purified immunoglobulin fraction obtained from rabbits immunised with cultured T. foetus served as both capture antibody and as biotinylated indicator antibody. While highly sensitive in the detection of antigen derived from cultured organisms, the assay showed poor sensitivity in the detection of antigen in the cervico-vaginal mucus of artificially infected heifers, with only 75% of culture-positive samples being considered positive for antigen. In a direct comparison, 23/122 samples from a naturally infected dairy herd gave positive cultures, while only 10/122 samples were considered antigen positive by EIA.

Nonsurgical collection of blastocysts from dairy goats.

In two trials, eight attempts were made to collect fertilized ova from dairy goats by nonsurgical methods. In both trials the cervix of each doe was dilated by inserting a Laminaria japonica tent device into the cervical canal prior to flushing. In Trial 1, an attempt was made to collect embryos from four nonsuperovulated does by flushing phosphate-buffered saline (PBS) through a rigid pipette. Little fluid and no embryos were recovered from the does. All four donors were in estrus two days after the procedure. In the second trial, FSH-superovulated does were collected on day 5 following estrus. The donors were anesthetized, and a modified Foley catheter was passed through the cervical canal. In three does, a 24 ga. two-way Foley was stiffened with a size 10 (French) polypropylene catheter which penetrated the Foley, extending 7 cm beyond the tip. Recovery of flushing medium with this device was minimal, and laparotomy of one doe revealed a punctured uterus. Replacement of this device with a different catheter, through which a polypropylene catheter (size 5 Fr.) penetrated only 1 to 2 cm, resulted in satisfactory return of infused PBS, and recovery of two blastocysts and one degenerated ovum from this doe. Use of the same device on a second doe without laparotomy resulted in collection of seven blastocysts and three degenerated ova. Of three observed donors that received Laminaria tents (including one which was not flushed) two were in estrus three days after the procedure, while unused synchronized recipients showed normal cycle lengths. Surgical transfer of two blastocysts from each donor to each of two synchronized recipients resulted in the birth of twin kids from one recipient doe. The study demonstrates the feasibility of embryo collection from dairy goats by nonsurgical means.

Zinc toxicity in ruminants.

Four natural occurrences of zinc toxicity in sheep and one in calves were studied. To assist in the confirmation of a diagnosis of zinc toxicity, 2 experiments were conducted in which sheep were given toxic amounts of zinc. The clinical findings, clinical pathology, and gross and microscopic pathology are given. Clinical manifestations included inappetance, loss of condition, diarrhoea with dehydration or subcutaneous oedema, profound weakness and jaundice. Significant rises in the concentration of zinc were usually found in the liver, kidney and pancreas, but occasionally in only 1 or 2 of these organs. Many affected sheep were anaemic. Pathological changes were found in the pancreas, kidney, liver, rumen, abomasum, small intestine and adrenal gland. Lesions in the kidney and abomasum apparently made the most significant contribution to the deterioration in health of affected animals, but the pancreas was the only organ consistently affected. The degenerative changes in the pancreas were mainly restricted to the exocrine portion of the organ, and regeneration of the damaged tissue was observed although exposure to toxic amounts of zinc continued. Attention is drawn to the importance of the pancreas in the diagnosis of zinc toxicity and in estimating the period of exposure.

Immunoglobulin isotype of specific antibodies in reproductive tract secretions and sera in Tritrichomonas foetus-infected heifers.

Four virgin heifers were experimentally inoculated intravaginally with 7 x 10(6) Tritrichomonas foetus, and 2 heifers served as uninfected controls. The durations of infection were 13, 20, 21, and 28 weeks, respectively. An ELISA that used whole T foetus antigen was used to detect anti-T foetus immunoglobulins (IgA, IgG1, IgG2, and IgM) in vaginal, cervical, and uterine secretions, and sera during the course of infection. The vaginal and cervical antibody responses were characterized by significantly increased T foetus-specific IgA and IgG1 at 7 to 9 weeks of infection, whereas uterine IgA and IgG1 responses peaked at 10 to 12 weeks. The antibody response in serum was predominantly of the IgG1 and IgG2 subclasses. In all reproductive tract regions, IgA persisted at least until the time of T foetus clearance, and usually longer. The next most persistent isotype was IgG1, lasting longest in the vagina, then cervix, and for the shortest time in the uterus. In local secretions, IgG2 was seen only transiently, increasing at weeks 13 to 15 in the vagina, and at weeks 10 to 12 in the cervix. Little IgM, relative to that present before infection, was detected in any secretion or serum, although cervical secretions had the greatest amount. Eight to 12 weeks after clearance, the 4 experimental heifers were inoculated intravaginally with 1 x 10(5) T foetus; transient infections (2 to 3 weeks' duration) were established in only 2 of 4 heifers, as determined by culturing of reproductive tract secretions.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of trichomonad-carrier cows.

Seven pregnant cows (gestation durations, 42 days to 7 months) were identified as culture-positive for Tritrichomonas foetus. For 6 of these pregnancies, 2 of the youngest fetuses were aborted, and calves were delivered by the other 4 cows. Two cows became carriers, maintaining trichomonad infections for 6 and 9 weeks after parturition. Carrier cows may be a source of reinfection for their herd mates. Hence, strategies for controlling trichomoniasis might include delaying the time of first breeding and aggressive culling of infected cows.

Epidemiologic and economic analyses of an unusually long epizootic of trichomoniasis in a large California dairy herd.

An epizootic of trichomoniasis in a large California dairy herd caused an estimated economic loss of $66,538 ($665/infected cow). Greatest losses were caused by infertility (about 50% of losses caused by excess days open). The disease continued in the herd, despite culling older bulls and replacing them with young uninfected bulls and despite institution of an artificial insemination (AI) breeding program for 2 high-production strings. The AI breeder's practice of checking for estrus by vaginal examination was implicated in the spread of the disease. Of 5 cows that became infected before or at conception, 1 had the infection throughout the gestation period and into the next lactation. The prevalence of trichomoniasis in the herd (estimated on the basis of culture results) was 10.67%. The culture method had a calculated sensitivity of only 58.7%. Of 940 cows in the herd, 132 aborted during the epizootic (8 aborted twice); 45 abortions would have been expected in a dairy herd of this size in the absence of trichomoniasis. In high-density mass-bred herds, conditions and/or management practices may be conducive for trichomoniasis transmission, and generally recommended control programs should be adjusted on such dairies. In particular, dairy operators should not assume that culling older bulls and replacing them with young uninfected bulls and that institution of an AI program will be effective in limiting the spread of the disease. Moreover, a diagnostic test with improved sensitivity would greatly assist in the identification of infected cows.

Induced Tritrichomonas foetus infection in beef heifers.

Four virgin beef heifers were inoculated intravaginally with 7 x 10(6) Tritrichomonas foetus organisms. Protozoal colonization of the vagina, cervix, and uterus developed within the first week after inoculation. Protozoa were no longer detected in secretions from these regions at approximately the same time in each heifer. Trichomonads were detected in reproductive tract secretions for 13 to 28 weeks. Eight weeks after clearance of trichomonads from the reproductive tract, a second infection was established in 2 of the 4 heifers by intravaginal inoculation of T foetus. The second infections were maintained for up to 4 weeks. The diagnostic sensitivity of wet-mount examination of the reproductive tract secretions was 30%, compared with 78% for culture of trichomonads in secretions. Collection and culturing of specimens of cervical and vaginal mucus provided the most reliable method for diagnosis of trichomoniasis during induced infection of heifers.

Efficacy of ipronidazole against trichomoniasis in beef bulls.

Preputial smegma samples from 195 beef bulls were collected repeatedly and cultured for Tritrichomonas foetus. Seventy-five (38.5%) of these bulls were positive for trichomonads on at least 1 culture. Sensitivity of the culture procedure (number of positive cultures/number of total cultures from known-positive bulls) was 81.6%. Storage of preputial smegma in lactated Ringer's solution at 5 C for 24 hours resulted in a 14% loss of sensitivity. Seventy-three of the 75 infected bulls were available for treatment and were alloted randomly to 2 groups. Bulls in both groups were treated with procaine penicillin (7,000 IU/kg, IM) for 2 days before ipronidazole treatment. Thirty grams of ipronidazole powder was dissolved in 60 ml of sterile water, and was given IM to group 1 bulls. Group 2 bulls were given a similar 30-g ipronidazole solution IM on day 1, and were given 15 g of ipronidazole dissolved in 30 ml of sterile water on days 2 and 3. Efficacy of treatment (ie, negative cultures of preputial smegma for trichomonads for 6 consecutive weeks after treatment) was 92.8% for the 42 bulls treated once and 100% for the 31 bulls treated 3 times.

Epidemiological studies of pig diseases: 1. Use of French protocols for risk factor assessment to predict the health status of Australian herds.

OBJECTIVE: To determine in Australian pig herds the accuracy of French protocols for risk factor assessment. PROCEDURE: Data on health indicators and risk factors were collected for three syndromes, 'pre-weaning diarrhoea', 'post-weaning diarrhoea' and 'respiratory problems', using the French protocols. The protocols were used on 118 occasions in 32 Western Australian pig herds during 3 years (1988 to 1991). RESULTS: There was a wide variation in pre-weaning performance, for example growth rate was 107 to 273 g/day (< 200 g/day in 33% of herds). Respiratory lesions at weaning were associated with poor pre-weaning performance. Post-weaning (21 days after weaning) growth rate was 114 to 408 g/day (< 250 g/day in 54% of herds). In the grower herds, 91% of herds had pneumonia, and growth rate was 439 to 625 g/day (< 550 g/day in 54% of herds). Pleurisy as well as pneumonia was associated with reduced growth rate. The risk factor most closely associated with respiratory health status was air volume per pig. CONCLUSION: Risk factors were most accurate at predicting the health status in post-weaning problems. A weaning weight of at least 7.9 kg and weaning age of 30 days optimised weaner performance. Stocking densities and shed designs providing at least 3 m3 air volume and 0.6 m2 floor space per pig throughout the growing phase should be considered for an improved respiratory health status. Australian pig sheds often do not provide a satisfactory environment for optimum health. The technique of risk factor assessment as an aid to the maintenance of health in pig herds is applicable in Australia, but further research is necessary to determine the most important Australian risk factors.

Epidemiological studies of pig diseases: 2. Post-weaning diarrhoea and performance in Western Australian pigs.

OBJECTIVE: To determine in Australian pig herds the accuracy of French protocols for risk factor assessment of post-weaning diarrhoea and illthrift. PROCEDURE: French protocols for the collection of data on health indicators and risk factors for post-weaning diarrhoea were conducted on 54 batches of weaner pigs from 28 Western Australian pig herds during three years. RESULTS: Large variations in post-weaning performance were found. About one-third of the batches were growing at < 200 g/day during the 3 weeks after weaning, and 54% had growth rates of < 250 g/day. Weaning age and weight of at least 30 days and 7.9 kg, respectively, optimised weaner performance. Other risk factors associated with little post-weaning diarrhoea and good weaner performance were high creep feed intakes, relatively little diarrhoea as suckers, and, contrary to expectations, large temperature fluctuations. CONCLUSION: Overall, the 'predictability' of post-weaning problems as assessed by measurement of risk status, was good. However, the model was less accurate at predicting the performance of a single batch of pigs.

Hemimelia and low marking percentage in a flock of Merino ewes and lambs.

Hemimelia at a prevalence of 11% of lambs marked, and low marking percentage (51%) was observed in a flock of mixed age Merino ewes and their lambs. Hemimelia occurred in one or 2 limbs of affected lambs. Lambs from other flocks on the farm were unaffected, and the condition was not reported from other farms. The condition had not occurred in the past, and has not recurred. No infectious or hereditary factors were implicated in the aetiology of the condition. Grazing Western Australian Blue Lupin stubble by the affected flock during and after joining was the only known difference between this flock and others on the farm.

Low alpha-tocopherol levels in livers of weaner sheep with nutritional myopathy.

Outbreaks of ovine weaner nutritional myopathy occurring in the southwest of Western Australia outside the recognised selenium-responsive areas have been investigated. One hundred and five sheep died in 3 outbreaks following 5 months grazing cereal stubble paddocks. Liver selenium and glutathione peroxidase activities, measured as an index of biological availability of dietary selenium, indicated that the selenium status of the animals was probably adequate. A comparison fo liver selenium and alpha-tocopherol concentrations and glutathione peroxidase activity was made with both selenium supplemented sheep and sheep affected with selenium-responsive nutritional myopathy. In all cases investigated in this study liver alpha-tocopherol levels in affected animals were low and this may be important in the aetiology of this myopathy.

Bovine trichomoniasis.

Although virtually unknown in Europe since the widespread adoption of artificial insemination (AI), infection by the sexually transmitted protozoan parasite Tritrichomonas foetus (Fig. 1) results in substantial economic losses throughout the major cattle-rearing areas of the world where natural breeding is relied upon. Infection by T. foetus is increasingly recognized as a significant cause of bovine infertility. In this review, Alex Yule, Susan Skirrow and Robert BonDurant summarize the current knowledge of bovine trichomoniasis and the problems of diagnosis and control of this economically important disease.