Role of Prolactin Receptors in Lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis (LAM) is a rare lung disease caused by mutations in the tumor suppressor genes encoding Tuberous Sclerosis Complex (TSC) 1 and TSC2. The protein product of the TSC2 gene is a well-known suppressor of the mTOR pathway. Emerging evidence suggests that the pituitary hormone prolactin (Prl) has both endocrine and paracrine modes of action. Here, we have investigated components of the Prl system in models for LAM. In a TSC2 (+/-) mouse sarcoma cell line, down-regulation of TSC2 using siRNA resulted in increased levels of the Prl receptor. In human LAM cells, the Prl receptor is detectable by immunohistochemistry, and the expression of Prl in these cells stimulates STAT3 and Erk phosphorylation, as well as proliferation. A high affinity Prl receptor antagonist consisting of Prl with four amino acid substitutions reduced phosphorylation of STAT3 and Erk. Antagonist treatment further reduced the proliferative and invasive properties of LAM cells. In histological sections from LAM patients, Prl receptor immuno reactivity was observed. We conclude that the Prl receptor is expressed in LAM, and that loss of TSC2 increases Prl receptor levels. It is proposed that Prl exerts growth-stimulatory effects on LAM cells, and that antagonizing the Prl receptor can block such effects.     

Biosensors for process monitoring

Summary A short review about the biosensor research activities for bioprocess monitoring in the F.R.G. after its reunification is given. The principles of biosensor applications are presented. In situ sensors and sensors based on the principles of flow injection analysis are studied. Some applications of a four-channel enzyme thermistor, bio-field effect transistors, and immunoanalysis systems for real process monitoring are presented.     

The evolution of food-producing glands in eusocial bees (Apoidea,Hymenoptera)1

A food-producing role for cephalic exocrine glands has arisen independently in both taxa of highly eusocial bees, Apis and Meliponini. With several exceptions, there is little evidence that food is produced by glands of solitary bees or by most bees at lower levels of sociality. We suggest that this association with sociality is due to four adaptive features of these glands: (1) food from the glands allows feces from queens and larvae to have a small volume, (2) the queen's fecundity can be increased, (3) nutrient recovery via cannibalism can be facilitated, and (4) rearing of emergency replacement queens is accelerated. Acceleration of the rearing of other castes and of queens in the normal process of colony fission is not clearly an advantage ascribed to these glands. Trophic eggs produced by meliponine colony workers are analogous to the secretions from food-producing glands in Meliponini and Apis workers.     

Effects of noradrenaline on45Ca2+ efflux from isolated rat islets of Langerhans

Noradrenaline caused a prompt but transient increase in the rate of⁴⁵Ca²⁺ efflux from isolated rat islets of Langerhans perifused in Ca²⁺ depleted medium. The response was modest in size and was unaffected by isosmotic replacement of NaCl with choline chloride or by inclusion of 0.5 mM dibutyryl cAMP in the perifusion medium, suggesting that it was not mediated by Na+: Ca²⁺ exchange nor by lowered cAMP. Despite its effect on⁴⁵Ca²⁺ efflux, noradrenaline treatment did not alter the kinetics of⁴⁵Ca²⁺ efflux in response to the muscarinic agonist, carbamylcholine, nor did it change the magnitude of the response to this agent. Simultaneous introduction of 20 mM glucose with noradrenaline prevented a rise in⁴⁵Ca²⁺ efflux and indeed resulted in inhibition of⁴⁵Ca²⁺ efflux. The data suggest that noradrenaline does not directly activate the mechanisms which regulate Ca²⁺ extrusion from islets cells, and they do not support a primary role for the Ca²⁺ efflux response in mediating adrenergic inhibition of insulin secretion.