Bilateral absence of the arcuate artery on the dorsum of the foot. With anomalous origin of dorsal metatarsal arteries

Bilateral absence of the arcuate artery was observed during routine dissection of the lower limbs of a 60-year-old male cadaver. Running distally on the dorsal aspect of both feet and opposite the tarso-metatarsal joint, the dorsalis pedis artery diverged 2cm lateral to the tendon of the extensor hallucis longus. The 2nd dorsal metatarsal artery was found originating from the dorsalis pedis artery opposite the intermediate cuneiform bone. The 3rd and 4th dorsal metatarsal arteries originated from the lateral tarsal artery. Although absence of the arcuate artery has been previously described, the arterial variant described here is thought to be distinct from those previously reported. The variant 2[nd] dorsal metatarsal artery was found to originate from the dorsalis pedis artery. Knowledge of anatomical variations of arteries supplying the feet and toes has important clinical significance in reconstructive surgery and in determining associated pathology

Pre-implantation immunosuppression in the pregnant rat: a possible role of seminal fluid

Successful reproduction involves exposure of the female to significant antigenic challenge. These experiments were done to test the possibility/hypothesis that seminal fluid has an immunosuppressive role in the early stages of pregnancy, which could protect the conceptus from immunological attack. A highly inbred strain of rat AO [RT1[u]] was used in this study. Eleven groups of animals were examined, one during the estrous phase of the ovarian cycle to provide base-line data, five during pseudopregnancy, designated as controls, and five groups during syngeneic pregnancy. Each group contained a minimum of six animals. For each animal, body weight and organ/tissue weights of the uterus, thymus, uterine and popliteal lymph nodes, were recorded together with total cell counts of the lymphoid tissues and their proliferating cell counts. The material was collected during each of the first five days of pregnancy and pseudopregnancy. The present study supports an immunological suppression by seminal fluid during early pregnancy as shown by a significant sustained depression of the proliferative lymphocyte response in the uterine regional lymph nodes

effect of stress on the immune system

It has been known for many years that mental attributes influence resistance to some diseases. The recently bereaved students preparing for examinations and individuals who are mentally depressed, all show reduced lymphocyte reactivity. The brain, especially the hypothalamus, controls neurotransmitter function of the autonomic nervous system. This influences immune reactivity through ACTH secretion by the pituitary which is regulated by feedback mechanisms of adrenal hormones levels. Consequently, primary and secondary lymphoid organs are affected. Stress can depress T-cell mitogenesis, natural killer [NK] cell activity and interleukin-2 [IL2] production. Cells react to stressful stimuli by synthesising and accumulating a specific group of stress proteins'. They are involved in assembling, disassembling and translocation of certain protein complexes through intracellular membranes. They can also interact with steroid hormone receptors, viral and cellular kinases, actin and tubulin. They have been implicated as being essential for viral replication and assembly of a variety of bacterial viruses. Stress-related thymic atrophy may be responsible for decreased cellular immunity. Profound uncontained stress may indeed cause body systems, including the immune system, to suffer with an increased vulnerability to disease

Aging and the immune system

The elderly are more susceptible to illness than young adults. Ageing is associated with varied immune response deficits involving cellular and humoral immunity. There are important age related changes into the T-cell compartment which may leave older patients relatively immunosuppressed. Thymic involution is strongly implicated in contributing to the age related loss of high affinity antibody response. In elderly humans and animals, there is a generalised decline into the ability to respond, and in fact the decline begins before an animal is half way through its normal lifespan. This decline can be measured in many immune phenomena. Both failure of helper T-cells and an increase in suppressor T-cell activity may contribute to the waining of the antibody response. Age related increase in cancer may be yet another manifestation of immune senescence. Since the ageing immune system may have a permissive role in diseases causing premature death, these ageing changes could actually determine the altimate life span of the species. Thus any intervention restoring normal immune function might indeed prolong life. If however, thymic involution serves physiologic compensatory role by protecting against autoimmune disease and keeping the immune system in check, thymic restoration could even accelerate the ageing process via autoimmune reactions