Dendrite-specific remodeling of Drosophila sensory neurons requires matrix metalloproteases, ubiquitin-proteasome, and ecdysone signaling

During neuronal maturation, dendrites develop from immature neurites into mature arbors. In response to changes in the environment, dendrites from certain mature neurons can undergo large-scale morphologic remodeling. Here, we show a group of Drosophila peripheral sensory neurons, the class IV dendritic arborization (C4da) neurons, that completely degrade and regrow their elaborate dendrites. Larval dendrites of C4da neurons are first severed from the soma and subsequently degraded during metamorphosis. This process is controlled by both intracellular and extracellular mechanisms: The ecdysone pathway and ubiquitin-proteasome system (UPS) are cell-intrinsic signals that initiate dendrite breakage, and extracellular matrix metalloproteases are required to degrade the severed dendrites. Surprisingly, C4da neurons retain their axonal projections during concurrent dendrite degradation, despite activated ecdysone and UPS pathways. These results demonstrate that, in response to environmental changes, certain neurons have cell-intrinsic abilities to completely lose their dendrites but keep their axons and subsequently regrow their dendritic arbors.     

Ghrelin does not mediate the somatotroph and corticotroph responses to the stimulatory effect of glucagon or insulin-induced hypoglycaemia in humans

OBJECTIVE: Acylated ghrelin, a gastric peptide, possesses a potent GH- but also significant ACTH/cortisol-releasing activity mediated by the activation of GH secretagogue receptors (GHS-R) at the hypothalamus-pituitary level. The physiological role of ghrelin in the control of somatotroph and corticotroph function is, however, largely unclear. Glucagon is known to induce a clear increase of GH, ACTH and cortisol levels in humans, at least after intramuscular administration. In fact, glucagon is considered to be a classical alternative to insulin-induced hypoglycaemia (ITT) for the combined evaluation of the function of GH and the hypothalamus-pituitary-adrenal (HPA) axis. We aimed to clarify whether ghrelin mediate the GH and corticotroph responses to intramuscular glucagon or ITT, which has recently been reported able to induce a surprising ghrelin decrease. SUBJECTS: To this aim we enrolled six normal young male subjects [age (mean +/- SD): 29.0 +/- 8.0 years, body mass index (BMI) 21.9 +/- 2.5 kg/m(2)]. DESIGN AND MEASUREMENTS: In all the subjects we studied ghrelin, GH, ACTH, cortisol and glucose levels after glucagon (GLU; 0.017 mg/kg intramuscularly), ITT (0.1 IU/kg insulin intravenously) or saline administration. RESULTS: Saline infusion was not followed by any significant variation in ghrelin, GH and glucose levels while ACTH and cortisol showed the expected spontaneous morning trend toward a decrease. GLU administration increased (P < 0.01) circulating GH, ACTH and cortisol as well as insulin and glucose levels. ITT induced an obvious increase (P < 0.01) of GH, ACTH and cortisol levels. The ITT-induced increases in GH and ACTH, but not cortisol, levels were higher (P < 0.01) than those after GLU. Circulating ghrelin levels were not modified by GLU. On the other hand, ghrelin levels underwent a transient reduction (P < 0.01) after insulin-induced hypoglycaemia. CONCLUSIONS: Ghrelin does not mediate the GH and ACTH responses to glucagon or to the ITT. In fact, ghrelin levels are not modified at all by glucagon and transiently decrease during the ITT. These findings support the assumption that ghrelin does not play a major role in the physiological control of somatotroph and corticotroph function.     

NADH oxidase activation is involved in arsenite-induced oxidative DNA damage in human vascular smooth muscle cells

Arsenic is atherogenic, carcinogenic, and genotoxic. Because atherosclerotic plaque has been considered a benign smooth muscle cell tumor, we have studied the effects of arsenite on DNA integrity of human vascular smooth muscle cells. By using single-cell alkaline electrophoresis, apparent DNA strand breaks were detected in a 4-hour treatment with arsenite at a concentration above 1 micromol/L. DNA strand breaks of arsenite-treated cells were increased by Escherichia coli formamidopyrimidine-DNA glycosylase and decreased by diphenylene iodinium, superoxide dismutase, catalase, pyruvate, DMSO, or D-mannitol. Extract from arsenite-treated cells showed increased capacity for producing superoxide when NADH was included in the reaction mixture; however, addition of arsenite to extract from untreated cells did not increase superoxide production. The superoxide-producing ability of arsenite-treated cells was also suppressed by diphenylene iodinium, 4,5-dihydroxy-1, 2-benzenedisulfonic acid disodium salt (Tiron), or superoxide dismutase. Superoxide production and DNA strand breaks in arsenite-treated cells were also suppressed by transfecting antisense oligonucleotides of p22phox, an essential component of NADH oxidase. Treatment with arsenite also increased the mRNA level of p22phox. These results suggest that arsenite activates NADH oxidase to produce superoxide, which then causes oxidative DNA damage. The result that arsenite at low concentrations increases oxidant levels and causes oxidative DNA damage in vascular smooth muscle cells may be important in arsenic-induced atherosclerosis.     

Effects of immediate versus delayed antihypertensive therapy on outcome in the Systolic Hypertension in Europe Trial

BACKGROUND: To assess the impact of immediate versus delayed antihypertensive treatment on the outcome of older patients with isolated systolic hypertension, we extended the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) trial by an open-label follow-up study lasting 4 years. METHODS: The Syst-Eur trial included 4695 randomized patients with minimum age of 60 years and an untreated blood pressure of 160-219 mmHg systolic and below 95 mmHg diastolic. The double-blind trial ended after a median follow-up of 2.0 years (range 1-97 months). Of 4409 patients still alive, 3517 received open-label treatment consisting of nitrendipine (10-40 mg daily) with the possible addition of enalapril (5-20 mg daily), hydrochlorothiazide (12.5-25 mg daily), or both add-on drugs. Non-participants (n = 892) were also followed up. RESULTS: Median follow-up increased to 6.1 years. Systolic pressure decreased to below 150 mmHg (target level) in 2628 participants (75.0%). During the 4-year open-label follow-up, stroke and cardiovascular complications occurred at similar frequencies in patients formerly randomized to placebo and those continuing active treatment. These rates were similar to those previously observed in the active-treatment group during the double-blind trial. Considering the total follow-up of 4695 randomized patients, immediate compared with delayed antihypertensive treatment reduced the occurrence of stroke and cardiovascular complications by 28% (P = 0.01) and 15% (P = 0.03), respectively, with a similar tendency for total mortality (13%, P = 0.09). In 492 diabetic patients, the corresponding estimates of long-term benefit (P < 0.02) were 60, 51 and 38%, respectively. CONCLUSIONS: Antihypertensive treatment can achieve blood pressure control in most older patients with isolated systolic hypertension. Immediate compared with delayed treatment prevented 17 strokes or 25 major cardiovascular events per 1000 patients followed up for 6 years. These findings underscore the necessity of early treatment of isolated systolic hypertension.     

The association between Helicobacter pylori infection and functional dyspepsia in patients with irritable bowel syndrome

OBJECTIVE: Irritable bowel syndrome (IBS) is associated with an exaggerated response to a variety of physiological and nonphysiological gastrointestinal stimuli. Many patients with IBS also have functional dyspepsia. Our aim was to examine the hypothesis that Helicobacter pylori (H. pylori) infection may predispose IBS patients to functional dyspepsia. METHODS: In 69 IBS patients, dyspeptic symptoms, H. pylori status, and sociodemographic and psychological variables (perceived stress, trait anxiety, and depression) were assessed. Sociodemographic and psychological variables were also evaluated in 52 control subjects. RESULTS: Mean scores for perceived stress (17.1 +/- 6.0 vs 14.9 +/- 6.0, p = 0.05), trait anxiety (45.6 +/- 9.1 vs 41.1 +/- 7.8, p = 0.004) and depression (9.9 +/- 8.4 vs 5.0 +/- 5.5, p = 0.0002) were higher in IBS patients than in controls. In all, 33 of the 69 patients (47.8%) had H. pylori infection, and this was associated with relevant symptoms of epigastric pain (odds ratio [OR] = 6.77, 95% confidence interval [CI] 1.89-24.3) and postprandial upper abdominal fullness (OR = 4.23, 95% CI 1.38-13.2). H. pylori infection and female gender were independent predictors of the presence of relevant dyspepsia (OR = 8.31, 95% CI 2.35-29.5 and 6.06, 95% CI 1.71-21.5, respectively). Symptom intensity was associated with the level of perceived stress (total relevant symptom number > or =3 vs <3, OR = 1.16 per point on a 40-point perceived stress scale, 95% CI 1.01-1.34). CONCLUSIONS: In IBS patients, the presence of dyspepsia is associated with H. pylori infection, female gender, and perceived stress.     

Multicenter trial of octreotide in patients with refractory acquired immunodeficiency syndrome-associated diarrhea

Diarrhea is a significant problem in patients with acquired immunodeficiency syndrome (AIDS). The aim of this study was to determine octreotide effectiveness in refractory AIDS-associated diarrhea. In a 3-week protocol, 129 patients with a stool weight of >500 g/day despite standard antidiarrheal therapy were randomized to receive octreotide or placebo (3:2 ratio). Octreotide dose was increased 100 μg weekly to a maximum of 300 μg three times a day based on weekly 72-hour stool collections. Subsequently, patients received open-label octreotide at doses of up to 500 μg three times a day. A 30% decrease in stool weight defined response. After 3 weeks, 48% of octreotide- and 39% of placebo-treated patients had responded (P = 0.43). At 300 μg three times a day, 50% of octreotide- and 30.1% of placebo-treated patients responded (P = 0.12). At a baseline stool weight of 1000–2000 g/day, 57% of octreotide- and 25% of placebo-treated patients responded (P = 0.06). Response rates based on CD4 counts, diarrhea duration, body weight, human immunodeficiency virus risk factor, and presence or absence of pathogens showed no benefit of octreotide. Adverse events were more frequent in the octreotide-treated group. In the doses studied, octreotide was not more effective than placebo in patients with refractory AIDS-associated diarrhea. This lack of effectiveness may be attributable to inadequate sample size, doses, and duration of study treatment.     

A fluorescent probe designed for studying protein conformational change

The usefulness of fluorescence in studying protein motions derives from its sensitivity, kinetic resolution, and compatibility with both live cells and physiological assays. Recent advances in microscopy and membrane protein purification have permitted the observation of fluorescence changes that accompany the functional transitions of complex eukaryotic membrane proteins. These techniques rely on probes that can clearly report the environmental changes of specific residues, but most commonly available side-chain-reactive probes are not well suited for this purpose. Here, we introduce a red Cys-reactive probe, aminophenoxazone maleimide (APM), designed with improved chemical and spectral properties for reporting protein conformational change. APM is compact, uncharged, and has a short linker between probe and protein, all of which ensure that it can closely track the motions of the side chain to which it is attached. It undergoes large polarity-dependent changes in Stokes shift, as well as large bathochromic shifts in both excitation maximum (from 521 nm in toluene to 598 nm in water) and emission maximum (580 nm to 633 nm). These polarity-dependent spectral changes offer a potentially simple means of relating fluorescence to local structure and motion, although they are partially offset by some complicating factors in APM fluorescence. We find that, like a rhodamine maleimide, APM senses the conformational changes underlying voltage sensing in the Shaker potassium channel, and it is superior at a site that shows limited reactivity to the rhodamine. The spectral characteristics of APM can also report subtle differences between aqueous positions in purified preparations of the beta2 adrenergic receptor.     

Intraoperative liver steatosis characterization using diffuse reflectance spectroscopy

Background

Liver steatosis is associated with poor outcome after liver transplantation and liver resection. There is a need for an accurate and reliable intraoperative tool to identify and quantify steatosis. This study aimed to investigate whether surface diffuse reflectance spectroscopy (DRS) measurements could detect liver steatosis on humans during liver surgery.

Prompt, Aggressive BP Lowering in High-Risk Patients

Various populations with hypertension have been singled out by current treatment guidelines as requiring more specific treatment. These include patients with stage 2 hypertension, black patients, and patients with coexistent diabetes mellitus and coronary heart disease. Hypertension in these groups is often associated with higher risk of cardiovascular morbidity and mortality. This article reviews current knowledge regarding hypertension in high-risk patient populations, with a particular focus on the importance of prompt, aggressive treatment to lower blood pressure and prevent cardiovascular disease progression. Such treatment includes the early use of multiple-drug therapy with agents that have complementary blood pressure-lowering mechanisms and provide protection from target organ damage. While 2- or 3-drug antihypertensive therapy in these high-risk groups has typically included a diuretic, other combinations of agents may be indicated. Evidence suggests that therapy with a calcium channel blocker and an inhibitor of the renin-angiotensin system is one effective strategy for lowering blood pressure and improving outcomes in these populations.