Measurement and Evaluation of Alternative Computer Architectures

The Army/Navy Computer Family Architecture Committee has developed an approach for quantifying the relative performance of alternative computer architectures.     

Long-term effects of urinary tract infections. The need for a controlled trial

Two series of children with urinary tract infections are compared: in one the infections were primarily covert, while in the other they were predominantly overt. Grade III reflux occurred only in the overt infection group, and the development or progression of renal clubbing and scarring was much more common in these patients. Now that effective, long-term prophylactic therapy for infection is available, the author urges that controlled trials be established to determine whether or not sterile reflux is harmful and whether or not ureteral reimplantation for reflux is of value.     

Infection of sheep with adult and larval Ostertagia circumcincta: abomasal morphology

The infection of parasite-naive sheep with approximately 15,000 adult Ostertagia circumcincta via abomasal cannulae resulted in marked changes in the structure and function of the abomasum. The functional changes, which have been characterised previously, included elevated abomasal pH and increased serum concentrations of pepsinogen and gastrin. Eight days after the transplant of adult worms, the abomasa of recipient animals were significantly heavier than those of controls (P < 0.001), the thickness of the fundic mucosa was greater (P < 0.01), there were fewer parietal cells (P < 0.01) and increases in the numbers of mitotic figures and mucus-producing cells. Mucous cell hyperplasia was also evident in the fundic mucosae of sheep receiving a trickle infection of infective, third-stage O. circumcincta larvae and was prominent within nodules associated with larval development. In non-nodular mucosa, there was hyperplasia of mucous cells and changes in the distribution of parietal cells. Decreases in the number of parietal cells at the gland base were offset by increases at a mid-gland level, probably due to chronic hypergastrinaemia, so that, overall, total parietal cell number was unaffected. Mucous cell hyperplasia and the diminution of parietal cell number are seen in a diverse range of disease states and may be mediated by host growth factors such as Transforming growth factor-alpha. Alternatively, the cellular and/or the secretory changes in response to the presence of adult worms are mediated by chemicals that are cytotoxic/inhibitory for parietal cells, and released by the parasites themselves.     

Interactions of acetylcholine and epinephrine on the dynamics of insulin release in vitro

An in vitro system for perifusion of rat pancreatic islets has been utilized to define the effects of epinephrine on acetylcholine-induced insulin release over varying concentrations of the two agents. Perifusion of islets with epinephrine before challenge with acetycholine produced marked enhancement of both phases of cholinergically induced insulin release; enhancement of the first phase being more marked with increase in acetylcholine concentration and the converse being observed with the second phase. Perifusion of islets with epinephrine during stimulation with acetylcholine produced inhibition of insulin release, an effect dependent upon the concentration of epinephrine and of acetylcholine. There was an order of difference in the acetycholine concentration needed to overcome significant epinephrine-mediated inhibition of the first phase of insulin release (5 X 10(-4) mug/ml) and that needed to overcome inhibition of the second phase (5 X 10(-3) mug/ml). Comparison of the effects of various concentrations of epinephrine on glucose- and acetyl-choline-induced insulin release revealed that epinephrine was a less potent inhibitor of the first phase of acetylcholine-induced insulin release than of the first phase of glucose-induced insulin release. These data provide some insight into the potential interactions between cholinergic and adrenergic autonomic systems in modifying insulin release.