Krüppel-like factor 4 (KLF4) is a transcription factor expressed in the vascular endothelium, where it promotes anti-inflammatory and anticoagulant states, and increases endothelial nitric oxide synthase expression. We examined the role of endothelial KLF4 in pulmonary arterial (PA) hypertension (PAH). Mice with endothelial KLF4 knockdown were exposed to hypoxia for 3 weeks, followed by measurement of right ventricular and PA pressures, pulmonary vascular muscularization, and right ventricular hypertrophy. The effect of KLF4 on target gene expression was assessed in lungs from these mice, verified in vitro by small interfering RNA (siRNA) knockdown of KLF4, and further studied at the promoter level with cotransfection experiments. KLF4 expression was measured in lung tissue from patients with PAH and normal control subjects. We found that, after hypoxia, right ventricular and PA pressures were significantly higher in KLF4 knockdown animals than controls. Knockdown animals also had more severe pulmonary vascular muscularization and right ventricular hypertrophy. KLF4 knockdown resulted in increased pulmonary expression of endothelin-1 and decreased expression of endothelial nitric oxide synthase, endothelin receptor subtype B, and prostacyclin synthase. Concordant findings were observed in vitro, both with siRNA knockdown of KLF4 and promoter activity assays. Finally, KLF4 expression was reduced in lungs from patients with PAH. In conclusion, endothelial KLF4 regulates the transcription of genes involved in key pathways implicated in PAH, and its loss exacerbates pulmonary hypertension in response to chronic hypoxia in mice. These results introduce a novel transcriptional modulator of PAH, with the potential of becoming a new therapeutic target.

Traditional host-based anomaly detection systems model normal behavior of applications by analyzing system call sequences. The current sequence is then examined (using the model) for anomalous behavior, which could correspond to attacks. Though these techniques have been shown to be quite effective, a key element is missing – the inclusion and utilization of the system call arguments. Recent research shows that sequence-based systems are prone to evasion. We propose an idea of learning different representations for system call arguments. Results indicate that this information can be effectively used for detecting more attacks than traditional sequence-based techniques, with reasonable storage and computational overhead.

For intrusion detection, the LERAD algorithm learns a succinct set of comprehensible rules for detecting anomalies, which could be novel attacks. LERAD validates the learned rules on a separate held-out validation set and removes rules that cause false alarms. However, removing rules with possible high coverage can lead to missed detections. We propose to retain these rules and associate weights to them. We present three weighting schemes and our empirical results indicate that, for LERAD, rule weighting can detect more attacks than pruning with minimal computational overhead.

Computer security research has two major aspects: intrusion prevention and intrusion detection. While the former deals with preventing the occurrence of an attack (using authentication and encryption techniques), the latter focuses on the detection of successful breach of security. Together, these complementary approaches assist in creating a more secure system. Intrusion detection systems (IDSs) are generally categorized as misusebased and anomaly-based. In misuse (signature) detection, systems are modeled upon known attack patterns and the test data is checked for occurrence of these patterns. Examples of signature-based systems include virus detectors that use known virus signatures and alert the user when the system has been infected by the same virus. Such systems have a high degree of accuracy but suffer from the inability to detect novel attacks. Anomaly-based intrusion detection [199] models normal behavior of applications and significant deviations from this behavior are considered anomalous. Anomaly detection systems can detect novel attacks but also generate false alarms since not all anomalies are hostile. Intrusion detection systems can also be categorized as network-based, which monitors network traffic, and host-based, where operating system events are monitored.There are two focal issues that need to be addressed for a host-based anomaly detection system: cleaning the training data, and devising an enriched representation for the model(s). Both these issues try to improve the performance of an anomaly detection system in their own ways. First, all the proposed techniques that monitor system call sequences rely on clean training data to build their model. The current audit sequence is then examined for anomalous behavior using some supervised learning algorithm. An attack embedded inside the training data would result in an erroneous model, since all future occurrences of the attack would be treated as normal. Moreover, obtaining clean data by hand could be tedious. Purging all malicious content from audit data using an automated technique is hence imperative.

Spontaneous renal artery dissection (SRAD) is a rare condition and usually presents with nonspecific symptoms. It is thus difficult to diagnose early enough to prevent complications of renal ischemia. SRAD has been associated with several disease processes and situations but a specific causal relationship has not yet been established. There are several treatment options available for SRAD with endovascular treatment being a safe and effective choice. Case PresentationA 65-year-old male patient presented to the emergency room upon request from his ex-wife due to signs of depression, he was tearful and expressed suicidal inclinations. Upon arrival in the emergency room the patient's blood pressure and pulse were 240/150 mm Hg and 105 beats per minute, respectively. He initially denied symptoms of blurry vision, seizures, focal weakness, headache, chest pain, swelling of the lower limbs, syncope, abdominal pain, and hematuria.The patient's medical history was significant for primary hypertension, chronic obstructive pulmonary disease, and obstructive sleep apnea. He had a history of smoking 30-pack per year. His basic metabolic panel showed a normal creatinine. Urine analysis was significant for proteinuria but no hematuria. He was found to have elevated b-type natriuretic peptide in whole blood. Chest X-ray revealed a slightly enlarged heart, and his electrocardiogram showed T-wave inversion in leads V1 and AVL suggestive of ischemia.The patient developed chest pain during hospitalization. A coronary angiogram was performed and revealed a 70 to 80% stenosis of the left anterior descending coronary artery. Percutaneous coronary intervention to the left anterior descending artery was done. Renal artery angiography was also performed during the same session to evaluate for renovascular hypertension. A dissection was discovered in the right renal artery (►Fig. 1).The dissection was verified by intravascular ultrasound assessment. There was no evidence that the dissection was caused by the catheterization procedure, and it was limited only to the right renal artery (►Fig. 2) and a magnetic resonance angiogram (MRA) (►Fig. 3) done before the percutaneous catheterization also showed the dissection in the right renal artery. The dissection was treated with balloon angioplasty and a bare metal stent. Patient's blood pressure preprocedure was 190/ 110 mm Hg and after percutaneous intervention of right renal artery patient's blood pressure was 120/71 mm Hg (►Fig. 4). DiscussionIsolated SRAD is rare with an incidence of only 0.036 to 0.049% of all arterial dissections.1 Renal artery dissections are generally associated with aortic dissection, being involved in 12.4% of all aortic dissections. 2 SRAD is difficult to diagnose and treat early given its nonspecific presentation. Only 200 cases of isolated SRAD have been reported so far and out of those 25% were found during autopsy. AbstractWe report an interesting case of a 65-year-old gentleman who presented with hypertensive emergency and was found to have an isolated spontan...