Prolactin: does it exert an up-modulation of the immune response in Trypanosoma cruzi-infected rats?

During the course of infection by Trypanosoma cruzi, the host immune system is involved in distinct, complex interactions with the endocrine system, and prolactin (PRL) is one of several hormones involved in immunoregulation. Although intensive studies attempting to understand the mechanisms that underlie Chagas' disease have been undertaken, there are still some pieces missing from this complex puzzle. Because data are scarce concerning the role of PRL involvement in Chagas' disease and taking into account the existence of crosstalk between neuroendocrine hormones and the immune system, the current study evaluates a possible up-regulation of the cellular immune response triggered by PRL in T. cruzi-infected rats and the role of PRL in reversing immunosuppression caused by the parasitic infection. The data shown herein demonstrate that PRL induces the proliferation of T lymphocytes, coupled with an activation of macrophages and the production of nitric oxide (NO), leading to a reduction in the number of blood trypomastigotes during the peak of parasitemia. During the acute phase of T. cruzi infection, an enhancement of both CD3+CD4+ and CD3+CD8+ T cell populations were observed in infected groups, with the highest numbers of these T cell subsets found in the infected group treated with PRL. Because NO is a signaling molecule involved in a number of cellular interactions with components of the immune system and the neuroendocrine system, PRL can be considered an alternative hormone able to up-regulate the host's immune system, consequently lowering the pathological effects of a T. cruzi infection.     

Cortisol levels in skimmed milk during the first 22?weeks of lactation and response to short-term metabolic stress and lameness in dairy cows

Background

Cortisol is secreted into blood in reaction to acute stress, but also in phases of diminished feed intake and changed animal behavior. As cows do not always show clear signs of discomfort, reliable diagnostic markers could be used to provide information regarding individual cows’ distress. The objective of this study was to establish an ether free immunoassay for the detection of cortisol and to determine values during the first 22 weeks of lactation. Furthermore, the response in milk cortisol levels was assessed during times of metabolic stress and pain associated symptoms of lameness.

Methods

Milk yield and composition, blood serum glucose, NEFA and BHBA as well as milk cortisol were determined in 24 multiparous Holstein-Friesian cows over the course of the first 22 weeks of lactation. Animals were further checked for signs of clinical diseases on a daily basis. Two feed restrictions over three days (FR; 70 % of precious ad libitum intake) were performed during the 4^th wk and the 21^st wk, respectively. An ELISA for cortisol measurement in easily accessible bovine skimmed milk was established and applied.

Results

On the last day of FR in early lactation, a reduction in milk yield and changes in serum metabolites compared to respective previous values were detected. The FR in mid-lactation resulted in no changes in milk production and serum metabolites. Milk cortisol was highest during first wk of lactation and remained on comparable levels thereafter. Milk yield and composition were not influenced by FR. Lameness resulted in enhanced milk cortisol levels.

Conclusion

Milk cortisol could be used as an indicator of painful symptoms such as lameness. Higher values of milk cortisol levels during first wk of lactation should be taken into account for interpretation.     

Garlic and hepatic coccidiosis: prophylaxis or treatment?

A study was conducted to investigate the protective and therapeutic effects of crude garlic (Allium sativum) against experimental infection with Eimeria stiedae in rabbits. Forty rabbits were divided into four groups of ten rabbits each: a healthy control group (HC); a challenged-garlic-protected group (CGP) which received a daily dose of 0.5 g/kg body weight (bwt) crude garlic for five successive days before challenge with E. stiedae; a challenged-garlic-treated group (CGT) which was treated with a daily dose of 0.5 g/kg bwt crude garlic for five successive days post-challenge; and an infected control group (IC). The challenge dose was 5?×?10⁴ sporulated E. stiedae oocysts per rabbit. Mortality rate, body weight gain, feed conversion ratio and faecal oocyst count were evaluated throughout the experiment. At the end of the experiment, all rabbits were killed and histopathological examination was performed. No mortalities were recorded in the HC and CGP groups, whilst mortality was found to be 20% and 40% in the CGT and IC groups, respectively. CGP rabbits had better body weight gain and lower numbers of oocysts than those in the CGT and IC groups. Hepatic lesions were less severe in the CGP group than in the CGT and IC groups. These results showed that oral administration of crude garlic ameliorated the adverse impacts of hepatic coccidiosis on rabbits when used as a prophylactic, but garlic was less effective as a therapeutic.     

Light at the end of the tunnel? Advances in the understanding and treatment of glaucoma and inherited retinal degeneration

Glaucoma and inherited retinal degeneration/dystrophy are leading causes of blindness in veterinary patients. Currently, there is no treatment for the loss of vision that characterizes both groups of diseases. However, this reality may soon change as recent advances in understanding of the disease processes allow researchers to develop new therapies aimed at preventing blindness and restoring vision to blind patients. Elucidating the molecular mechanisms of retinal ganglion cell death in glaucoma patients has led to the development of neuroprotective drugs which protect retinal cells and their function from the disastrous effects of elevated pressure. Identification of the genetic mutation responsible for inherited degenerations and dystrophies of the outer retina has enabled researchers using gene therapy to restore vision to blind dogs. Other patients may benefit from retinal transplantation, stem cell therapy, neuroprotective drugs, nutritional supplementation and even retinal prostheses. It is possible that soon it will be possible to restore sight to some blind patients.     

Do device that simulate methane capture equipment,as a mask located in the head of dairy cows affect their welfare?

The objective of this study was to determine if device that simulate methane capture equipment (DSMC) located in the frontal part of the head of dairy cows affect animal welfare using productive, behavioral, biochemical and physiological indicators. Twenty Holstein dairy cows were assigned to one of the two following treatments: cows with DSMC (CDSMC, n=10) and cows without methane capture devices (CC, n=10). Treatment did not affect neither milk production nor biochemical blood. The group CDSMC tended to ruminate less (P=0.06) and tended to eat more (P=0.08) frequently than the group CC. In conclusion, considering the data set, the welfare of the cows was not significantly affected by the use of DSMC located in their heads.     

Anthelmintic treatment and the suppression of egg production in gastro-intestinal nematodes of sheep and cattle: fact or fallacy?

Evidence for a temporary suppression of egg production in gastro-intestinal nematodes of sheep and cattle following anthelmintic treatment is reviewed and the possible relevance of this phenomenon to the appropriate sampling time in the faecal egg count reduction test is discussed. The results of this review suggest that if such suppressive effects do occur in sheep nematodes, then they are unlikely to be of much practical significance and that little benefit would be derived from extending the post-treatment sampling interval beyond 10 days. For cattle nematodes, however, the issues are less readily obvious but indicate, at least when testing for resistance to persistent anthelmintics, that adoption of a longer post-treatment interval might be advisable.     

Surgical treatment of synovial sepsis: Is endoscopy the best approach?

Treatment of synovial sepsis (septic arthritis, bursitis and tenosynovitis) typically involves surgical lavage of the infected synovial cavity(ies). The two most used techniques are through-and-through needle lavage and endoscopic lavage. Endoscopic lavage is considered to have several advantages, and anecdotally, there appears to be a general shift towards favouring this technique. However, there are only a limited number of published studies directly comparing the outcomes of the two treatment techniques. The available published literature suggests that the outcomes (short-term survival, return to work) are comparable. Further studies are required to expand the available veterinary literature and to assess such factors as the costs associated with the different treatment methods. A variation in diagnostic values used for diagnosing synovial sepsis is apparent in the current literature and further clarification of inclusion/diagnostic criteria would be useful for clinicians.     

The changing epidemiology of yellow fever and dengue, 1900 to 2003: full circle?

Yellow fever and dengue are old diseases, having caused major epidemics in centuries past. Both were effectively controlled in the mid 1900s, yellow fever in Francophone Africa by vaccination and yellow fever and dengue in the Americas by effective control of the principal urban vector of both viruses, Aedes aegypti. In the last 25 years of the 20th century, however, there was a resurgence of yellow fever in Africa, and of dengue worldwide. The factors responsible for this resurgence are discussed, as are current options for prevention and control.     

A sheep in wolf's clothes: can neutrophils direct the immune response?

The intercellular transfer of cell membranes and integral membrane proteins has been reported for a wide variety of cells, including cells involved in the immune response, and the passively acquired proteins can alter recipient cell function. Cell membrane transfer can occur by a variety of mechanisms and conditions such as inflammation, cell death, or cell stress increase the release of membrane fragments by donor cells. This review focuses specifically on neutrophils as the recipients of cell membranes and integral membrane proteins. Neutrophils are often the first cells recruited to sites of inflammation where there is ample opportunity to acquire membrane proteins shed by a variety of cells. Our recent investigations have confirmed that bovine neutrophils have an impressive capacity to rapidly acquire membrane proteins from necrotic and apoptotic cells. Furthermore, these acquired proteins can alter neutrophil phenotype and function and we hypothesise that they may enhance their capacity to integrate innate and adaptive immune responses. The implications of these alterations to neutrophil function are discussed within the context of vaccine and novel immune therapy design.     

Prior and concomitant dehydroepiandrosterone treatment affects immunologic response of cultured macrophages infected with Trypanosoma cruzi in vitro?

DHEA, a steroid hormone synthesized from cholesterol by cells of the adrenal cortex, plays an essential role in enhancing the host's resistance to different experimental infections. Receptors for this hormone can be found in distinct immune cells (especially macrophages) that are known to be the first line defense against Trypanosoma cruzi infection. These cells operate through an indirect pathway releasing nitric oxide (NO) and cytokines such TNF-α and IL-12 which in turn trigger an enhancement of natural killer cells and lymphocytes which finally secrete pro and anti-inflammatory cytokines. The effects of pre- and post-infection DHEA treatment on production of IL-12, TNFα and NO were evaluated. T. cruzi infected macrophages post treated with DHEA displayed enhanced concentrations of TNF-α, IL-12 and NO. Probably, the mechanisms that induced the production of cytokines by infected cells are more efficient when the immune system has been stimulated first by parasite invasion, suggesting that the protective role of DHEA is greater when administered post infection.