Computed tomography versus digital subtraction angiography for the diagnosis of obscure gastrointestinal bleeding.

PURPOSE: The diagnostic yield of computed tomography angiography (CTA) compared to digital subtraction angiography (DSA) for major obscure gastrointestinal bleeding (OGIB) is not known. Aim of the study was to prospectively evaluate the diagnostic yield of CTA versus DSA for the diagnosis of major OGIB. MATERIAL AND METHODS: The institutional review board approved the study and informed consent was obtained from each patient. Patients with major OGIB were prospectively enrolled to undergo both CTA and DSA. Two blinded radiologists each reviewed the CTA and DSA images retrospectively and independently. Contrast material extravasation into the gastrointestinal lumen was considered diagnostic for active bleeding. Primary end point of the study was the diagnostic yield, defined as the frequency a technique identified an active bleeding or a potential bleeding lesion. The diagnostic yield of CTA and DSA were compared by McNemar's test. RESULTS: 24 consecutive patients (11 men; median age 64 years) were included. CTA and DSA identified an active bleeding or a potential bleeding lesion in 92% (22 of 24 patients; 95% CI 72%-99%) and 29% (7 of 24 patients; 95% CI 12%-49%) of patients, respectively (p<0.001). CTA and DSA identified an active bleeding in 42% (10 of 24; 95% CI 22%-63%) and 21% (5 of 24; 95% CI 7%-42%) of patients, respectively (p=0.06). CONCLUSION: Due to the lower invasiveness and higher diagnostic yield CTA should be favored over DSA for the diagnosis of major OGIB.

N-terminal pro brain natriuretic peptide in the management of patients in the medical emergency department (PROMPT): correlation with disease severity, utilization of hospital resources, and prognosis in a large, prospective, randomized multicentre trial.

AIMS: N-terminal pro brain natriuretic peptide (NT-proBNP) is a potent marker of heart failure and other cardiac diseases. The value of NT-proBNP testing in the medical emergency department (ED) was assessed in patients >65 years old. METHODS AND RESULTS: This large, prospective, randomized, controlled, multicentre trial was conducted in six medical EDs. Data for evaluation of the primary endpoint of hospitalization were available for 1086 patients. Median NT-proBNP was 582 pg/mL. A total of 16% of patients presented with NT-proBNP <150 pg/mL (low), 55% with NT-proBNP between 150 and 1800 pg/mL (intermediate), and 29% with NT-proBNP >1800 pg/mL (high). NT-proBNP was positively correlated with hospital admission [ odds ratio (OR) for high vs. low 2.9, P < 0.0001], length of stay (8.5 days vs. 3.5 days for high vs. low, P < 0.01), in-hospital death (3.9% vs. 0% for high vs. low, P < 0.01), 6 months re-hospitalization (OR for high vs. low 5.1, P < 0.0001), and 6 months death or re-hospitalization (OR for high vs. low 5.7, P < 0.0001). Knowledge of NT-proBNP had no significant effect on the primary endpoint hospital admission and the secondary endpoints intermediate/intensive care unit (IMC/ICU) admission, length of stay, re-hospitalization and death, or re-hospitalization in the total cohort. However, patients with high open NT-proBNP (>1800 pg/mL) were more likely to be admitted to the hospital (P < 0.05) and IMC/ICU (P < 0.05), whereas patients with low open NT-proBNP (<150 pg/mL) were less likely to be admitted (P < 0.05) compared with patients with blinded NT-proBNP. CONCLUSION: Although NT-proBNP does not affect overall hospitalization, it is associated with better stratification of patient care and is strongly correlated with subsequent utilization of hospital resources and prognosis.

Collection of annotated data in a clinical validation study for alarm algorithms in intensive care--a methodologic framework.

INTRODUCTION: Monitoring of physiologic parameters in critically ill patients is currently performed by threshold alarm systems with high sensitivity but low specificity. As a consequence, a multitude of alarms are generated, leading to an impaired clinical value of these alarms due to reduced alertness of the intensive care unit (ICU) staff. To evaluate a new alarm procedure, we currently generate a database of physiologic data and clinical alarm annotations. METHODS: Data collection is taking place at a 12-bed medical ICU. Patients with monitoring of at least heart rate, invasive arterial blood pressure, and oxygen saturation are included in the study. Numerical physiologic data at 1-second intervals, monitor alarms, and alarm settings are extracted from the surveillance network. Bedside video recordings are performed with network surveillance cameras. RESULTS: Based on the extracted data and the video recordings, alarms are clinically annotated by an experienced physician. The alarms are categorized according to their technical validity and clinical relevance by a taxonomy system that can be broadly applicable. Preliminary results showed that only 17% of the alarms were classified as relevant, and 44% were technically false. DISCUSSION: The presented system for collecting real-time bedside monitoring data in conjunction with video-assisted annotations of clinically relevant events is the first allowing the assessment of 24-hour periods and reduces the bias usually created by bedside observers in comparable studies. It constitutes the basis for the development and evaluation of "smart" alarm algorithms, which may help to reduce the number of alarms at the ICU, thereby improving patient safety.

Intensive care unit alarms--how many do we need?

OBJECTIVE: To validate cardiovascular alarms in critically ill patients in an experimental setting by generating a database of physiologic data and clinical alarm annotations, and report the current rate of alarms and their clinical validity. Currently, monitoring of physiologic parameters in critically ill patients is performed by alarm systems with high sensitivity, but low specificity. As a consequence, a multitude of alarms with potentially negative impact on the quality of care is generated. DESIGN: Prospective, observational, clinical study. SETTING: Medical intensive care unit of a university hospital. DATA SOURCE: Data from different medical intensive care unit patients were collected between January 2006 and May 2007. MEASUREMENTS AND MAIN RESULTS: Physiologic data at 1-sec intervals, monitor alarms, and alarm settings were extracted from the surveillance network. Video recordings were annotated with respect to alarm relevance and technical validity by an experienced physician. During 982 hrs of observation, 5934 alarms were annotated, corresponding to six alarms per hour. About 40% of all alarms did not correctly describe the patient condition and were classified as technically false; 68% of those were caused by manipulation. Only 885 (15%) of all alarms were considered clinically relevant. Most of the generated alarms were threshold alarms (70%) and were related to arterial blood pressure (45%). CONCLUSION: This study used a new approach of off-line, video-based physician annotations, showing that even with modern monitoring systems most alarms are not clinically relevant. As the majority of alarms are simple threshold alarms, statistical methods may be suitable to help reduce the number of false-positive alarms. Our study is also intended to develop a reference database of annotated monitoring alarms for further application to alarm algorithm research.

Optimized multidetector computed tomographic protocol for the diagnosis of active obscure gastrointestinal bleeding: a feasibility study.

OBJECTIVE: The purpose of this feasibility study was to prospectively evaluate an optimized multidetector computed tomographic protocol for the diagnosis of active obscure gastrointestinal bleeding (OGIB). METHODS: Between October 2006 and February 2008, patients admitted for active OGIB were included in this prospective unicenter study. Water was administered orally and rectally as neutral luminal contrast material. A contrast-enhanced 16-row multidetector computed tomography (MDCT) was performed in the arterial and venous phases. Mesenteric digital subtraction angiography was carried out immediately after MDCT as standard of reference. RESULTS: Six patients were included in this study. Multidetector computed tomography identified the bleeding site and source in 5 (83%) of the patients. Digital subtraction angiography was performed in 4 patients, and the result was positive in 1 (25%) of the patients. Multidetector computed tomography detected the site and source of bleeding in 2 patients whose digital subtraction angiographic result was negative. CONCLUSIONS: The results of this feasibility study indicate that optimized MDCT is an excellent diagnostic tool for the diagnosis of active OGIB.

Outcome in a large unselected series of patients with acute pancreatitis.

BACKGROUND/AIMS: The objective of this study was to assess the outcome in a large unselected population of patients with acute pancreatitis treated at a single university center. METHODOLOGY: We performed a retrospective analysis of 364 patients with acute pancreatitis and evaluated outcome, morbidity and mortality in relation to different treatment modalities. RESULTS: 238 patients suffered from interstitial-edematous pancreatitis, 126 patients from the necrotizing form. ICU treatment was necessary for 174 patients (48%). Minimally-invasive CT guided drainage techniques were used in 73 patients (20%) with pancreatic necroses but also in seven patients with edematous pancreatitis (2%), which showed extrapancreatic tissue necrosis. The overall hospital mortality was 14% (5.5% for patients with edematous pancreatitis vs. 30% for patients with necrotizing pancreatitis). CONCLUSIONS: In patients with the edematous form a small subpopulation showed peripancreatic tissue necrosis without necrosis of the pancreas itself, which was related to higher mortality rates than expected for patients with edematous pancreatitis. Regarding therapeutic procedures interventional treatment modalities should be considered as alternative treatment modalities.

Obscure gastrointestinal bleeding: preoperative CT-guided percutaneous needle localization of the bleeding small bowel segment.

A 57-year-old woman presented with obscure gastrointestinal bleeding. Double balloon enteroscopy, angiography, and surgery including intraoperative enteroscopy failed to identify the bleeding site. Multidetector computed tomography (CT) depicted active bleeding of a small bowel segment. The bleeding segment was localized by CT-guided percutaneous needle insertion and subsequently removed surgically.

Continuous non-invasive arterial pressure technique improves patient monitoring during interventional endoscopy.

INTRODUCTION: Close monitoring of arterial blood pressure (BP) is a central part of cardiovascular surveillance of patients at risk for hypotension. Therefore, patients undergoing diagnostic and therapeutic procedures with the use of sedating agents are monitored by discontinuous non-invasive BP measurement (NIBP). Continuous non-invasive BP monitoring based on vascular unloading technique (CNAP, CN Systems, Graz) may improve patient safety in those settings. We investigated if this new technique improved monitoring of patients undergoing interventional endoscopy. METHODS: 40 patients undergoing interventional endoscopy between April and December 2007 were prospectively studied with CNAP(R) in addition to standard monitoring (NIBP, ECG and oxygen saturation). All monitoring values were extracted from the surveillance network at one-second intervals, and clinical parameters were documented. The variance of CNAP values were calculated for every interval between two NIBP measurements. RESULTS: 2660 minutes of monitoring were recorded (mean 60.1+/-34.4 min/patient). All patients were analgosedated with midazolam and pethidine, and 24/40 had propofol infusion (mean 90.9+/-70.3 mg). The mean arterial pressure for CNAP was 102.4+/-21.2 mmHg and 106.8+/-24.8 mmHg for NIBP. Based on the first NIBP value in an interval between two NIBP measurements, BP values determined by CNAP showed a maximum increase of 30.8+/-21.7% and a maximum decrease of 22.4+/-28.3% (mean of all intervals). DISCUSSION: Conventional intermittent blood pressure monitoring of patients receiving sedating agents failed to detect fast changes in BP. The new technique CNAP improved the detection of rapid BP changes, and may contribute to a better patient safety for those undergoing interventional procedures.

Recovery from respiratory failure after decompression laparotomy for severe acute pancreatitis.

We present three cases of patients (at the age of 56 years, 49 years and 74 years respectively) with severe acute pancreatitis (SAP), complicated by intra-abdominal compartment syndrome (ACS) and respiratory insufficiency with limitations of mechanical ventilation. The respiratory situation of the patients was significantly improved after decompression laparotomy (DL) and lung protective ventilation was re-achieved. ACS was discussed followed by a short review of the literature. Our cases show that DL may help patients with SAP to recover from severe respiratory failure.

Antisense oligonucleotides against the lipid phosphatase SHIP2 improve muscle insulin sensitivity in a dietary rat model of the metabolic syndrome.

The lipid phosphatase SH2 domain-containing lipid phosphatase (SHIP2) has been implicated in the regulation of insulin sensitivity, but its role in the therapy of insulin-resistant states remains to be defined. Here, we examined the effects of an antisense oligonucleotide (AS) therapy directed against SHIP2 on whole body insulin sensitivity and insulin action in liver and muscle tissue in a dietary rodent model of the metabolic syndrome, the high-fat-fed (HF) rat. Whole body insulin sensitivity was examined in vivo by insulin tolerance tests before and after the intraperitoneal application of an AS directed against SHIP2 (HF-SHIP2-AS) or a control AS (HF-Con-AS) in HF rats. Insulin action in liver and muscle was assayed by measuring the activation of protein kinase B (Akt) and insulin receptor substrate (IRS)-1/2 after a portal venous insulin bolus. SHIP2 mRNA and protein content were quantified in these tissues by real-time PCR and immunoblotting, respectively. In HF-SHIP2-AS, whole body glucose disposal after an insulin bolus was markedly elevated compared with HF-Con-AS. In liver, insulin activated Akt similarly in both groups. In muscle, insulin did not clearly activate Akt in HF-Con-AS animals, whereas insulin-induced Akt phosphorylation was sustained in SHIP2-AS-treated rats. IRS-1/2 activation did not differ between the experimental groups. SHIP2 mRNA and protein content were markedly reduced only in muscle. In standard diet-fed controls, SHIP2-AS reduced SHIP2 protein levels in liver and muscle, but it had no significant effect on insulin sensitivity. We conclude that treatment with SHIP2-AS can rapidly improve muscle insulin sensitivity in dietary insulin resistance. The long-term feasibility of such a strategy should be examined further.

Frequency and outcome of patients with nonthyroidal illness syndrome in a medical intensive care unit.

Acute and chronic critical conditions are associated with reduced serum levels of free triiodothyronine (FT(3)), free thyroxine FT(4), and thyrotropin, known as nonthyroidal illness syndrome (NTIS). It is still controversial whether these changes reflect a protective mechanism or a maladaptive process during prolonged illness. However, larger studies to determine the prevalence of the NTIS and its association with outcome in medical intensive care units (ICUs) are missing. Complete thyroid hormone levels from 247 of 743 patients admitted to our ICU between October 2002 and February 2004 were retrospectively evaluated. From these patients, Acute Physiology and Chronic Health II scores, ICU mortality, length of stay, mechanical ventilation, and concomitant medication were recorded. Ninety-seven patients (44.1%) had low FT(3) levels indicating an NTIS, either with normal (23.6%) or reduced (20.5%) serum thyrotropin levels. Of 97 patients with NTIS, 24 (23.3%) also showed reduced serum FT(4) levels. The NTIS was significantly associated with Acute Physiology and Chronic Health II scores, mortality, length of stay, and mechanical ventilation. In a multivariate Cox regression analysis, the combination of low FT(3) and low FT(4) was an independent risk factor for survival. Nonthyroidal illness syndrome is frequent at a medical ICU. A reduction of FT(4) together with FT(3) is associated with an increase in mortality and might reflect a maladaptive process, thereby worsening the disease.

Glucagon production of the rat insulinoma cell line INS-1-A quantitative comparison with primary rat pancreatic islets.

The rat insulinoma cell line INS-1 is the most commonly used clonal cell model in pancreatic beta-cell research. Considering the multihormonality of many insulinomas we examined as to how INS-1 cells comply with the notion of resembling a pure beta-cell line. Glucagon immunoassays revealed that INS-1 cells secrete glucagon in a similar range as islets. By immunohistochemistry we detected a cytoplasmic glucagon signal in INS-1 cells which colocalized with C-peptide. Cellular content of preproglucagon-mRNA and glucagon protein in INS-1 cells was less than two percent of the respective values in islets, which probably reflects differences in the intracellular metabolism and/or secretory pathways. Taken together, it is obvious that INS-1 cells do not represent an exclusively insulin producing beta-cell line.

Stimulatory short-term effects of free fatty acids on glucagon secretion at low to normal glucose concentrations.

While free fatty acids (FFA) are well known as insulin secretagogues, their effects on pancreatic alpha cells have been mostly neglected. In the present study we therefore systematically analyzed the glucagon metabolism of rat pancreatic islets under the influence of FFA. Primary islets were incubated in the presence or absence of 200 micromol/L albumin-complexed palmitate or oleate at 2.8 mmol/L versus 16.7 mmol/L glucose and glucagon secretion was monitored over 8 hours. In addition to these time-course experiments, dose dependency of palmitate-induced effects was tested by a 2-hour incubation with 50 to 300 micromol/L albumin-complexed palmitate at 2.8 mmol/L and 5.6 mmol/L glucose. Apart from glucagon secretion, intracellular immunoreactive glucagon and cellular preproglucagon-mRNA (PPG-mRNA) content were determined from the remaining cell lysates. FFA, especially palmitate, induced a significant and dose-dependent increase of glucagon secretion (in average 2-fold above control) during the first 120 minutes of incubation at low to normal glucose (2.8 and 5.6 mmol/L). There was no significant glucagonotropic effect of FFA at concomitant 16.7 mmol/L glucose. Intracellular glucagon as well as cellular PPG-mRNA content were found to be dose-dependently diminished by palmitate when compared with untreated controls at 5.6 mmol/L glucose. The present analysis therefore points to a new role for FFA as a nutritient secretagogue and a modulator of alpha-cellular glucagon metabolism.

Correlation between iron status and genetic hemochromatosis (codon C282Y) in a large German population.

BACKGROUND: Genetic hemochromatosis leads to iron overload in many tissues and may lead to liver cirrhosis and hepatocellular carcinoma. Early diagnosis and therapy are crucial. Since 80-100% of hemochromatosis patients of European origin are homozygous for a cysteine to tyrosine exchange in the HFE gene at codon 282, genetic screening might be useful. Representative population studies are needed to evaluate the phenotype of people heterozygous and homozygous for the C282Y mutation. OBJECTIVE: To determine the correlation between parameters of iron metabolism and the hemochromatosis genotype in a large population-based study. METHODS: A representative population-based survey, the Diabetomobil study, analyzed 5,083 German probands. Serum transferrin saturation and ferritin levels were determined, and the C282Y mutation of the HFE gene was analyzed by restriction fragment length polymorphism-polymerase chain reaction analysis. RESULTS: Nine of 373 probands with a transferrin saturation > 55% (2.4%) and none of 264 randomly selected probands with a transferrin saturation < or = 55% (0%) were homozygous for the C282Y mutation. Three of the nine homozygous probands had ferritin values less than 250 micrograms/L. The frequency of the heterozygous genotype was 8.8%, and the percentage of heterozygous probands increased with increasing levels of transferrin saturation. CONCLUSION: We propose a population screening strategy with an initial transferrin saturation test, followed by genotyping for the C282Y mutation if the transferrin saturation is above 55%, regardless of the ferritin level. Heterozygous individuals with higher transferrin saturation values may be protected against iron loss but may also be more susceptible for certain liver diseases, depending on the simultaneous prevalence of other diseases.

Decreasing IRS-2 expression in pancreatic beta-cells (INS-1) promotes apoptosis, which can be compensated for by introduction of IRS-4 expression.

IRS-2 plays a pivotal role in the control of pancreatic beta-cell growth. Here, the effect of altering IRS-2 expression levels in the pancreatic beta-cell line, INS-1, was examined. Adenoviral-mediated increased in IRS-2 protein levels protected against fatty acid (FFA)-induced apoptosis, associated with increased activation of PKB and decreased levels of activated caspase-9. Conversely, decreasing endogenous IRS-2 in INS-1 cells, using adenoviral-mediated expression of IRS-2 antisense, caused a three-fold increase in baseline apoptosis that was further enhanced in the presence of FFA. This was associated with decreased activation of PKB and increased caspase-9 activation. Although IRS-4 is not normally expressed in beta-cells, it was found that adenoviral-mediated introduction of IRS-4 into INS-1 cells enhanced glucose/IGF-1 induced mitogenesis, and protected against FFA-induced apoptosis, similarly to IRS-2. Moreover, expression of IRS-4 in INS-1 cells depleted of IRS-2 levels by IRS-2 antisense, was able to compensate for the lack of IRS-2 and reduce apoptosis in these cells back to normal. Thus, in beta-cells IRS-4 and -2 have similar biological functions. Also, this study further emphasizes the importance of IRS-2 signaling in control of beta-cell survival.

IRS-3 inhibits IRS-2-mediated signaling in pancreatic beta-cells.

IRS-2 plays an important role in the control of pancreatic beta-cell growth, however it is unclear if other IRS family members are also involved. Using recombinant adenoviruses, IRS-1, -2 and -3 expression was varied in the beta-cell line, INS-1. Increased IRS-1 expression had no appreciable effect on beta-cell growth. However, increased IRS-2 expression augmented glucose/IGF-1 induced beta-cell growth mitogenesis and decreased apoptosis due to glucose-deprivation. In contrast, increased IRS-3 expression significantly inhibited mitogenesis and increased apoptosis. IRS-3 was intransiently located to the beta-cell plasma membrane, and appeared to be inert in terms of IGF-1 induced signaling. However, increased IRS-3 expression blocked glucose/IGF-1 induced IRS-2 translocation from the cytosol to the plasma membrane, dampening IRS-2/IGF-1R interaction and subsequent activation of the PI3K/PKB/GSK3 signaling pathway. In contrast, glucose/IGF-1 induced Erk-1/-2 and p70S6K activation were unaffected by IRS-3. These data emphasize the importance of IRS-2/PI3K/PKB signal transduction for beta-cell growth and survival.

Intracellular depletion of insulin: a comparative study with palmitate, oleate and elaidate in INS-1 cells.

OBJECTIVE: Free fatty acids (FFAs) deplete the intracellular insulin stores of pancreatic beta-cells. It has been suggested that this results from a lipotoxic dysregulation of both insulin secretion and insulin synthesis. In the present study, this hypothesis was tested within a 12-h time-course by directly relating the FFA-induced loss of intracellular insulin to corresponding parameters of insulin secretion and de novo biosynthesis. Palmitate, cis-monoenic oleate and the trans-monoenic elaidate were employed as model FFAs to elucidate potentially different effects due to chain length and configuration. METHODS: INS-1 cells were incubated for 1, 4 or 12 h with 11.2 mmol/l glucose with 200 micromol/l palmitate, oleate or elaidate and compared with non-FFA-exposed controls with respect to content and secretion of immunoreactive insulin (IRI). Biosynthesis of insulin was monitored by pulse-labeling experiments and by Northern blot analysis. RESULTS: IRI content dropped by 50-60% after a short-term exposure with all FFAs employed (P< or =0.001). It tended to recover after 12 h of treatment with oleate and elaidate but not with palmitate. FFA treatment increased insulin secretion by 25% (P< or =0.05) which could not account quantitatively for the intracellular loss. FFA-induced changes in insulin biosynthesis did not correlate clearly with the FFA-induced intracellular loss. CONCLUSIONS: The FFA-induced loss of IRI is an acute effect independent of the FFA employed. It cannot be sufficiently explained by FFA-induced perturbances of IRI secretion and biosynthesis. We therefore postulate an additional FFA-triggered mechanism, e.g. intracellular IRI degradation.

Differential activation mechanisms of Erk-1/2 and p70(S6K) by glucose in pancreatic beta-cells.

Glucose can activate the mitogen-activated kinases, Erk-1/2, and the ribosomal-S6 kinase, p70(S6K), in beta-cells, contributing to an increase in mitogenesis. However, the signaling mechanism by which glucose induces Erk-1/2 and p70(S6K) phosphorylation activation is undefined. Increased glucose metabolism increases [Ca(2+)](i) and [cAMP], and it was investigated if these secondary signals were linked to glucose-induced Erk-1/2 and p70(S6K) activation in pancreatic beta-cells. Blocking Ca(2+) influx with verapamil, or inhibiting protein kinase A (PKA) with H89, prevented glucose-induced Erk-1/2 phosphorylation. Increasing cAMP levels by GLP-1 potentiated glucose-induced Erk-1/2 phosphorylation via PKA activation. Elevation of [Ca(2+)](i) by glyburide potentiated Erk-1/2 phosphorylation, which was also inhibited by H89, suggesting increased [Ca(2+)](i) preceded PKA for glucose-induced Erk-1/2 activation. Adenoviral-mediated expression of dominant negative Ras in INS-1 cells decreased IGF-1-induced Erk-1/2 phosphorylation but had no effect on that by glucose. Collectively, our study indicates that a glucose-induced rise in [Ca(2+)](i) leads to cAMP-induced activation of PKA that acts downstream of Ras and upstream of the MAP/Erk kinase, MEK, to mediate Erk-1/2 phosphorylation via phosphorylation activation of Raf-1. In contrast, glucose-induced p70(S6K) activation, in the same beta-cells, was mediated by a distinct signaling pathway independent of Ca(2+)/cAMP, most likely via mTOR-kinase acting as an "ATP-sensor."

Protein kinase B/Akt prevents fatty acid-induced apoptosis in pancreatic beta-cells (INS-1).

Free fatty acids (FFA) have been reported to reduce pancreatic beta-cell mitogenesis and to increase apoptosis. Here we show that the FFA, oleic acid, increased apoptosis 16-fold in the pancreatic beta-cell line, INS-1, over a 18-h period as assessed by Hoechst 33342/propidium iodide staining and caspase-3 and -9 activation, with negligible necrosis. A parallel analysis of the phosphorylation activation of protein kinase B (PKB) showed this was reduced in the presence of FFA that correlated with the incidence of apoptosis. At stimulatory 15 mm glucose and/or in the added presence of insulin-like growth factor 1, FFA-induced beta-cell apoptosis was lessened compared with that at a basal 5 mm glucose. However, most strikingly, adenoviral mediated expression of a constitutively active PKB, but not a "kinase-dead" PKB variant, essentially prevented FFA-induced beta-cell apoptosis under all glucose/insulin-like growth factor 1 conditions. Further analysis of pro-apoptotic downstream targets of PKB, implicated a role for PKB-mediated phosphorylation inhibition of glycogen synthase kinase-3alpha/beta and the forkhead transcription factor, FoxO1, in protection of FFA-induced beta-cell apoptosis. In addition, down-regulation of the pro-apoptotic tumor suppressor protein, p53, via PKB-mediated phosphorylation of MDM2 might also play a role in partially protecting beta-cells from FFA-induced apoptosis. Adenoviral mediated expression of wild type p53 potentiated FFA-induced beta-cell apoptosis, whereas expression of a dominant negative p53 partly inhibited beta-cell apoptosis by approximately 50%. Hence, these data demonstrate that PKB activation plays an important role in promoting pancreatic beta-cell survival in part via inhibition of the pro-apoptotic proteins glycogen synthase kinase-3alpha/beta, FoxO1, and p53. This, in turn, provides novel insight into the mechanisms involved in FFA-induced beta-cell apoptosis.