Deconstructing maize population structure.

Association studies have rarely been used in plant genetics, in part because of the risk of false positives caused by population structure. A study of flowering time in maize makes the first use of recent 'structured association' methods-statistical approaches that use independent loci to control for the effects of structure and admixture.     

Regulation of sodium and body fluid homeostasis during development: Implications for the pathogenesis of hypertension

The spontaneously hypertensive rat (SHR) is an important animal model of human essential hypertension. During the first month of life, increased retention of sodium is present in the SHR which appears to be mediated by the renin-angiotensin system. The present review will discuss the role that increased activity of the renin-angiotensin system plays in sodium/body fluid regulation during early development. It is hypothesized that disordered regulation of sodium/body fluid homeostasis during this stage leads to pathological cardiovascular regulation in adulthood. Through an understanding of the relationship between sodium/body fluid balance in the young and cardiovascular function in the adult insights may be gained into both the pathological state of hypertension and the critical role played by early development in shaping homeostatic mechanisms in adulthood.     

Identification of 2-deoxyecdysone from the mite,Tyrophagus putrescentiae

2-Deoxyecdysone was purified from the miteTyrophagus putrescentiae and monitored by a radioimmunoassay. The compound was identified by GC-MS and LC-MS. This is the first report of an endogenous ecdysteroid from a mite.     

Multiplication of human-derivedPneumocystis carinii in severe combined immunodeficient (SCID) mice

clinically healthy SCID mice were infected intratracheally withPneumocystis carinii (PC) of human origin. The data obtained provides unambiguous evidence that progressive multiplication of PC organisms of human origin takes place in the lungs of experimentally infected animals. SCID mice that were infected with human-derived PC also revealed a markedly greater number of mouse PC organisms in their lungs than the controls. All the SCID recipients of human PC died by day 65 post infection, whereas the controls, housed under identical conditions, started dying significantly later due to severe mouse pneumocystosis. This animal model could be used for the maintenance and propagation of human PC, and for evaluating strategies for treating human pneumocystosis.     

Deficiency of fibrinolytic enzyme activities in the serum of patients with Alzheimer-type dementia

Previously we reported that there is a kallikrein deficiency in the cerebral tissue of patients with Alzheimer-type dementia. The present study was performed to investigate protease changes in the serum of these patients. The results showed that the kallikrein activity was normal, but that the activities of plasmin and urokinase were significantly low. The present findings indicate a derangement in the clotting and fibrinolytic systems in Alzheimer patients.     

Blockade of GABAB receptors accelerates amygdala kindling development.

The aim of this study was to investigate the putative role of GABAB receptors in the development of amygdala kindling in rats. The effects of the GABAB blocker CGP 35348 and the GABAB agonist baclofen on the progressive development of behavioural seizure symptoms (stages 1-5 classified by Racine) and duration of after-discharges (AD) were studied. CGP 35348 at a dose of 300 mg/kg i.p., which blocks central GABAB receptors, moderately but consistently accelerated the development of behavioural seizure symptoms. CGP 35348 had no marked effect on the duration of ADs corresponding to the different seizure stages. L-baclofen (6 mg/kg i.p.) had a dual effect on kindling development. It retarded the development of the behavioural symptoms, but increased the duration of AD. In conclusion, the results suggest that synaptically-released GABA activated GABAB receptors and thereby exerted a depressant effect on kindling development.     

Regulation of sodium and body fluid homeostasis during development: implications for the pathogenesis of hypertension.

The spontaneously hypertensive rat (SHR) is an important animal model of human essential hypertension. During the first month of life, increased retention of sodium is present in the SHR which appears to be mediated by the renin-angiotensin system. The present review will discuss the role that increased activity of the renin-angiotensin system plays in sodium/body fluid regulation during early development. It is hypothesized that disordered regulation of sodium/body fluid homeostasis during this stage leads to pathological cardiovascular regulation in adulthood. Through an understanding of the relationship between sodium/body fluid balance in the young and cardiovascular function in the adult insights may be gained into both the pathological state of hypertension and the critical role played by early development in shaping homeostatic mechanisms in adulthood.