S Arkins — Page 3 | PubMed Health

PubMed1986

Effects of formalin footbathing on foot disease and claw quality in dairy cows.

Two experiments on the effect of routine footbathing in 5 per cent formalin in preventing foot diseases and improving claw horn quality of dairy cows are described. Treatment four times a week significantly (P less than 0.05) reduced the incidence of interdigital lesions but had no significant effect on the incidence of the individual interdigital lesions or on the incidence of individual or overall diseases of the claw horn. A two year study using a divided footbath demonstrated significant improvements in some aspects of claw quality in digits footbathed in formalin. Formalin treated digits had a lower incidence and severity of erosio ungulae (P less than 0.001) a lower moisture content (P less than 0.001) and a reduced severity of haemorrhage of the sole at some sites in the claw compared with untreated digits. Formalin treatment, however, had no significant effect on the incidence of either clinical or subclinical lesions of the claw horn. The improvement in the horn quality of claws treated with formalin for six months did not increase with a further year of treatment.

Animals↗

PubMedDate not supplied

The immune-endocrine loop during aging: role of growth hormone and insulin-like growth factor-I.

Why a primary lymphoid organ such as the thymus involutes during aging remains a fundamental question in immunology. Aging is associated with a decrease in plasma growth hormone (somatotropin) and IGF-I, and this somatopause of aging suggests a connection between the neuroendocrine and immune systems. Several investigators have demonstrated that treatment with either growth hormone or IGF-I restores architecture of the involuted thymus gland by reversing the loss of immature cortical thymocytes and preventing the decline in thymulin synthesis that occurs in old or GH-deficient animals and humans. The proliferation, differentiation and functions of other components of the immune system, including T and B cells, macrophages and neutrophils, also demonstrate age-associated decrements that can be restored by IGF-I. Knowledge of the mechanism by which cytokines and hormones influence hematopoietic cells is critical to improving the health of aged individuals. Our laboratory has recently demonstrated that IGF-I prevents apoptosis in promyeloid cells, which subsequently permits these cells to differentiate into neutrophils. We also demonstrated that IL-4 acts much like IGF-I to promote survival of promyeloid cells and to activate the enzyme phosphatidylinositol 3'-kinase (PI 3-kinase). However, the receptors for IGF-I and IL-4 are completely different, with the intracellular beta chains of the IGF receptor possessing intrinsic tyrosine kinase activity and the alpha and gammac subunit of the heterodimeric IL-4 receptor utilizing the Janus kinase family of nonreceptor protein kinases to tyrosine phosphorylate downstream targets. Both receptors share many of the components of the PI 3-kinase signal transduction pathway, converging at the level of insulin receptor substrate-1 or insulin receptor subtrate-2 (formally known as 4PS, or IL-4 Phosphorylated Substrate). Our investigations with IGF-I and IL-4 suggest that PI 3-kinase inhibits apoptosis by maintaining high levels of the anti-apoptotic protein Bcl-2. The sharing of common activation molecules, despite vastly different protein structures of their receptors, forms a molecular explanation for the possibility of cross talk between IL-4 and IGF-I in regulating many of the events associated with hematopoietic differentiation, proliferation and survival.

Aging↗