Identification of Brain-Penetrant ATP-Competitive mTOR Inhibitors for CNS Syndromes.

The allosteric inhibitor of the mechanistic target of rapamycin (mTOR) everolimus reduces seizures in tuberous sclerosis complex (TSC) patients through partial inhibition of mTOR functions. Due to its limited brain permeability, we sought to develop a catalytic mTOR inhibitor optimized for central nervous system (CNS) indications. We recently reported an mTOR inhibitor (1) that is able to block mTOR functions in the mouse brain and extend the survival of mice with neuronal-specific ablation of the Tsc1 gene. However, 1 showed the risk of genotoxicity in vitro. Through structure-activity relationship (SAR) optimization, we identified compounds 9 and 11 without genotoxicity risk. In neuronal cell-based models of mTOR hyperactivity, both corrected aberrant mTOR activity and significantly improved the survival rate of mice in the Tsc1 gene knockout model. Unfortunately, 9 and 11 showed limited oral exposures in higher species and dose-limiting toxicities in cynomolgus macaque, respectively. However, they remain optimal tools to explore mTOR hyperactivity in CNS disease models.

High CD44 Immunoexpression Correlates with Poor Overall Survival: Assessing the Role of Cancer Stem Cell Markers in Oral Squamous Cell Carcinoma Patients from the High-Risk Population of Pakistan.

Oral squamous cell carcinoma (OSCC) is a top-ranked cancer in the Pakistani population, and patient survival has remained unchanged at ∼50% for several decades. Recent advances have claimed that a subset of tumour cells, called cancer stem cells (CSCs), are responsible for tumour progression, treatment resistance, and metastasis, which leads to a poor prognosis. This study investigated the impact of CSC markers expression on overall survival (OS) and disease-free survival (DFS) of OSCC patients. Materials and Methods. Immunohistochemistry was used to evaluate CD44, CD133, L1CAM, and SOX2 expression in a well-characterized cohort of 100 Pakistani patients with primary treatment naïve OSCC. The immunoreactivity for each marker was correlated with patient clinicopathologic characteristics, oral cancer risk chewing habits, and survival. The minimum follow-up time for all patients was five years, and survival estimates were calculated using the Kaplan-Meier method and Cox proportional hazards model. Results. In this cohort of 100 patients, there were 57 males and 43 females. The median OS and DFS time durations observed were 64 and 52.5 months, respectively. Positive expression for CD44, CD133, L1CAM, and SOX2 was observed in 33%, 23%, 41%, and 63% of patients. High CD44 expression correlated with decreased OS (P=0.047) but did not influence DFS. However, CD133, L1CAM, and SOX2 had no effect on either OS or DFS. Tonsils, nodal involvement, and AJCC stage were independent predictors of worse OS and DFS both. Conclusion. Of the CSC markers investigated here, only CD44 was a predictor for poor OS. CD44 was also associated with advanced AJCC and T stages. Interestingly, CD133 was significantly lower in patients who habitually consumed oral cancer risk factors.

Discovery of a Brain-Penetrant ATP-Competitive Inhibitor of the Mechanistic Target of Rapamycin (mTOR) for CNS Disorders.

Recent clinical evaluation of everolimus for seizure reduction in patients with tuberous sclerosis complex (TSC), a disease with overactivated mechanistic target of rapamycin (mTOR) signaling, has demonstrated the therapeutic value of mTOR inhibitors for central nervous system (CNS) indications. Given that everolimus is an incomplete inhibitor of the mTOR function, we sought to develop a new mTOR inhibitor that has improved properties and is suitable for CNS disorders. Starting from an in-house purine-based compound, optimization of the physicochemical properties of a thiazolopyrimidine series led to the discovery of the small molecule 7, a potent and selective brain-penetrant ATP-competitive mTOR inhibitor. In neuronal cell-based models of mTOR hyperactivity, 7 corrected the mTOR pathway activity and the resulting neuronal overgrowth phenotype. The new mTOR inhibitor 7 showed good brain exposure and significantly improved the survival rate of mice with neuronal-specific ablation of the Tsc1 gene. These results demonstrate the potential utility of this tool compound to test therapeutic hypotheses that depend on mTOR hyperactivity in the CNS.

Successful Percutaneous Treatment of an Arteriovenous Malformation of the Toe.

Arteriovenous malformations (AVMs) of the toe are a rare entity. To the author's knowledge, there are only 2 published case reports, and both patients underwent amputation of the affected digits. Little is known about the optimal treatment of AVMs involving the toe. The authors present the case of a 20-year-old male with a large AVM of the second toe, which was successfully treated with intra-arterial sodium tetradecyl sulfate. Percutaneous treatment of these lesions is possible and should be considered before amputation.

A point-of-care microfluidic biochip for quantification of CD64 expression from whole blood for sepsis stratification.

Sepsis, a potentially life-threatening complication of an infection, has the highest burden of death and medical expenses in hospitals worldwide. Leukocyte count and CD64 expression on neutrophils (nCD64) are known to correlate strongly with improved sensitivity and specificity of sepsis diagnosis at its onset. A major challenge is the lack of a rapid and accurate point-of-care (PoC) device that can perform these measurements from a minute blood sample. Here, we report a PoC microfluidic biochip to enumerate leukocytes and quantify nCD64 levels from 10 µl of whole blood without any manual processing. Biochip measurements have shown excellent correlation with the results from flow cytometer. In clinical studies, we have used PoC biochip to monitor leukocyte counts and nCD64 levels from patients' blood at different times of their stay in the hospital. Furthermore, we have shown the biochip's utility for improved sepsis diagnosis by combining these measurements with electronic medical record (EMR).

NHC Ligands Tailored for Simultaneous Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings.

An exceptionally hindered class of enantiopure NHC ligands has been developed. While racemic forms had previously been utilized, a scalable and practical route to the enantiopure form of this ligand class is described utilizing a Buchwald-Hartwig N,N-diarylation in a highly sterically demanding environment. Using this newly accessible ligand class, nickel-catalyzed enantioselective reductive coupling reactions of aldehydes and alkynes have been developed. These studies illustrate that the newly available NHC ligands are well suited for simultaneous control of regio- and enantioselectivity, even in cases with internal alkynes possessing only very subtle steric differences between two aliphatic substituents. The steric demand of the new ligand class enables a complementary regiochemical outcome compared with previously described enantioselective processes. Using this method, a number of allylic alcohol derivatives were efficiently obtained with high regioselectivity (up to >95:5) and high enantioselectivity (up to 94% ee). The reaction conditions can also be extended to the reaction of aldehydes and allenes, providing silyl-protected allylic alcohol derivatives possessing a terminal methylene substituent. Computational studies have explained the origin of the exceptional steric demand of this ligand class, the basis for enantioselectivity, and the cooperative relationship of the aldehyde, alkyne, and ligand in influencing enantioselectivity.

Comparative Study of the Limitations and Challenges in Atom-Transfer C-H Oxidations.

A comparative study is disclosed that seeks to highlight the current limitations and challenges that exist in the field of atom-transfer C-H oxidations. State-of-the-art methods are benchmarked in order to showcase clear differences and similarities. A novel Mn-mediated method for C-H oxidation is disclosed that serves as a rapid and simple method for aliphatic C-H hydroxylation. Finally, two methods that allow for C-H oxidation in the presence of pyridine-containing substrates are studied, something that is rare in the field but of great interest to the chemical community.

Mechanistic Basis for Regioselection and Regiodivergence in Nickel-Catalyzed Reductive Couplings.

The control of regiochemistry is a considerable challenge in the development of a wide array of catalytic processes. Simple π-components such as alkenes, alkynes, 1,3-dienes, and allenes are among the many classes of substrates that present complexities in regioselective catalysis. Considering an internal alkyne as a representative example, when steric and electronic differences between the two substituents are minimal, differentiating among the two termini of the alkyne presents a great challenge. In cases where the differences between the alkyne substituents are substantial, overcoming those biases to access the regioisomer opposite that favored by substrate biases often presents an even greater challenge. Nickel-catalyzed reductive couplings of unsymmetrical π-components make up a group of reactions where control of regiochemistry presents a challenging but important objective. In the course of our studies of aldehyde-alkyne reductive couplings, complementary solutions to challenges in regiocontrol have been developed. Through careful selection of the ligand and reductant, as well as the more subtle reaction variables such as temperature and concentration, effective protocols have been established that allow highly selective access to either regiosiomer of the allylic alcohol products using a wide range of unsymmetrical alkynes. Computational studies and an evaluation of reaction kinetics have provided an understanding of the origin of the regioselectivity control. Throughout the various procedures described, the development of ligand-substrate interactions plays an essential role, and the overall kinetic descriptions were found to differ between protocols. Rational alteration of the rate-determining step plays a key role in the regiochemistry reversal strategy, and in one instance, the two possible regioisomeric outcomes in a single reaction were found to operate by different kinetic descriptions. With this mechanistic information in hand, the empirical factors that influence regiochemistry can be readily understood, and more importantly, the insights suggest simple and predictable experimental variables to achieving a desired reaction outcome. These studies thus present a detailed picture of the influences that control regioselectivity in a specific catalytic reaction, but they also delineate strategies for regiocontrol that may extend to numerous classes of reactions. The work provides an illustration of how insights into the kinetics and mechanism of a catalytic process can rationalize subtle empirical findings and suggest simple and rational modifications in procedure to access a desirable reaction outcome. Furthermore, these studies present an illustration of how important challenges in organic synthesis can be met by novel reactivity afforded by base metal catalysis. The use of nickel catalysis in this instance not only provides an inexpensive and sustainable method for catalysis but also enables unique reactivity patterns not accessible to other metals.

Value of Adjusted Blood Requirement Index in determining failure to control bleed in patients with variceal bleeding.

INTRODUCTION: Variceal bleeding is a serious complication in patients with cirrhosis. Among the criteria that were proposed in Baveno conferences, the Adjusted Blood Requirement Index (ABRI) has not been validated prospectively in clinical practice. We therefore aim to evaluate the measurement of ABRI as a marker of failure to control bleeding and to evaluate the consistency of ABRI in relation to other criteria of failure to control variceal bleeding. PATIENTS AND METHODS: All patients with variceal bleeding who presented to Aga Khan University Hospital from January 2010 to December 2012 who were administered transfusion of packed red blood cells were included after obtaining informed consent. All patients were managed as per the standard protocol with intravenous terlipressin along with band ligation and injection of cyanoacrylate in cases of esophageal and fundal varices, respectively. Hemoglobin and hematocrit were measured every 6 h for 48 h and then every 12 h until 5 days of index bleed in each patient. Packed cells were transfused if hemoglobin decreased below 8 g/dl. The number of blood units transfused, change in hemoglobin values, and ABRI were calculated after each unit of blood transfusion till 120 h. In patients in whom bleed could not be controlled, an ABRI value of 0.75 or more was compared with other Baveno IV-based parameters that define failure to control variceal bleeding. RESULTS: During the study period, 137 eligible patients with variceal bleed were admitted. The mean age of the patients was 52±12 years. The majority of patients (50.4%) were in Child-Pugh class B, followed by 38% in Child-Pugh class C. According to the Baveno IV criteria, overall failure to control acute variceal bleeding occurred in 52 (37.9%) patients. Excluding ABRI, failure to control bleeding was found in 22/137 (16%) patients, whereas ABRI-based criteria showed that in 34/137 (24.8%) patients, bleeding could not be controlled. There were only four (2.9%) patients with variceal bleeding in whom ABRI and other additional Baveno IV-based criteria for failure to control bleeding were present. When ABRI was compared with other criteria for failure to control bleeding, it showed a sensitivity and specificity of 19 and 25%, respectively. CONCLUSION: This study showed that ABRI is not a useful additional tool to define failure to control bleeding after variceal hemorrhage in cirrhotic patients.

Non-Directed Allylic C-H Acetoxylation in the Presence of Lewis Basic Heterocycles.

We outline a strategy to enable non-directed Pd(II)-catalyzed C-H functionalization in the presence of Lewis basic heterocycles. In a high-throughput screen of two Pd-catalyzed C-H acetoxylation reactions, addition of a variety of N-containing heterocycles is found to cause low product conversion. A pyridine-containing test substrate is selected as representative of heterocyclic scaffolds that are hypothesized to cause catalyst arrest. We pursue two approaches in parallel that allow product conversion in this representative system: Lewis acids are found to be effective in situ blocking groups for the Lewis basic site, and a pre-formed pyridine N-oxide is shown to enable high yield of allylic C-H acetoxylation. Computational studies with density functional theory (M06) of binding affinities of selected heterocycles to Pd(OAc)2 provide an inverse correlation of the computed heterocycle-Pd(OAc)2 binding affinities with the experimental conversions to products. Additionally, 1H NMR binding studies provide experimental support for theoretical calculations.

Efficient search of chemical space: navigating from fragments to structurally diverse chemotypes.

We introduce a novel strategy to sample bioactive chemical space, which follows-up on hits from fragment campaigns without the need for a crystal structure. Our results strongly suggest that screening a few hundred or thousand fragments can substantially improve the selection of small-molecule screening subsets. By combining fragment-based screening with virtual fragment linking and HTS fingerprints, we have developed an effective strategy not only to expand from low-affinity hits to potent compounds but also to hop in chemical space to substantially novel chemotypes. In benchmark calculations, our approach accessed subsets of compounds that were substantially enriched in chemically diverse hit compounds for various activity classes. Overall, half of the hits in the screening collection were found by screening only 10% of the library. Furthermore, a prospective application led to the discovery of two structurally novel histone deacetylase 4 inhibitors.

Current management and surgical outcomes of medically intractable epilepsy.

Epilepsy is one of the most common neurologic disorders in the world. While anti-epileptic drugs (AEDs) are the mainstay of treatment in most cases, as many as one-third of patients will have a refractory form of disease indicating the need for a neurosurgical evaluation. Ever since the first half of the twentieth century, surgery has been a major treatment option for epilepsy, but the last 10-15 years in particular has seen several major advances. As shown in relatively recent studies, resection is more effective for medically intractable epilepsy (MIE) than AED treatment alone, which is why most clinicians now endorse a neurosurgical consultation after approximately two failed regimens of AEDs, ultimately leading to decreased healthcare costs and increased quality of life. Temporal lobe epilepsy (TLE) is the most common form of MIE and comprises about 80% of epilepsy surgeries with the majority of patients gaining complete seizure-freedom. As the number of procedures and different approaches continues to grow, temporal lobectomy remains consistently focused on resection of mesial structures such as the amygdala, hippocampus, and parahippocampal gyrus while preserving as much of the neocortex as possible resulting in optimum seizure control with minimal neurological deficits. MIE originating outside the temporal lobe is also effectively treated with resection. Though not as successful as TLE surgery because of their frequent proximity to eloquent brain structures and more diffuse pathology, epileptogenic foci located extratemporally also benefit from resection. Favorable seizure outcome in each of these procedures has heavily relied on pre-operative imaging, especially since the massive surge in MRI technology just over 20 years ago. However, in the absence of visible lesions on MRI, recent improvements in secondary imaging modalities such as fluorodeoxyglucose positron emission computed tomography (FDG-PET) and single-photon emission computed tomography (SPECT) have lead to progressively better long-term seizure outcomes by increasing the neurosurgeon's visualization of supposed non-lesional foci. Additionally, being historically viewed as a drastic surgical intervention for MIE, hemispherectomy has been extensively used quite successfully for diffuse epilepsies often found in pediatric patients. Although total anatomic hemispherectomy is not utilized as commonly today, it has given rise to current disconnective techniques such as hemispherotomy. Therefore, severe forms of hemispheric developmental epilepsy can now be surgically treated while substantially decreasing the amount of potential long-term complications resulting from cavitation of the brain following anatomical hemispherectomy. Despite the rapid pace at which we are gaining further knowledge about epilepsy and its surgical treatment, there remains a sizeable underutilization of such procedures. By reviewing the recent literature on resective treatment of MIE, we provide a recent up-date on epilepsy surgery while focusing on historical perspectives, techniques, prognostic indicators, outcomes, and complications associated with several different types of procedures.

Functionalized chromans and isochromans via a diastereoselective Pd(0)-catalyzed carboiodination.

A diastereoselective approach to isochromans and chromans via Pd(0)-catalyzed carboiodination is reported. The transformations using this methodology display excellent yields and diastereoselectivities as well as broad functional group compatibility. The selectivity observed in these cyclizations, forming isochroman or chroman targets, is postulated to originate from the minimization of A(1,2) strain and axial-axial interactions, respectively. This method has also been used to highlight the concept of reversible oxidative addition to carbon-iodine bonds in polyiodinated substrates.

Impact of a bleeding care pathway in the management of acute upper gastrointestinal bleeding.

OBJECTIVES: Upper gastrointestinal (UGI) bleeding carries high morbidity and mortality. The use of a bleeding care pathway (BCP) may improve outcomes, but the results are inconsistent in various studies. METHODS: A BCP for patients with UGI bleed with admission in a bleeding care unit (BCU) has been in use at our hospital since 2005. Prior to this, a high dependency unit was used for management of all emergencies including UGI bleeding. We compared the length of stay in the bleeding care/high dependency unit, total hospital stay, time to UGI endoscopy after admission, and survival between pre-2005 and post-2005 patients. RESULTS: Five hundred and fifty-one patients were admitted with acute UGI bleed in the last 5 years; 121 belonged to pre-BCP (2004) period and 430 after implementation of the pathway (2005-2008). The mean (SD) time to UGI endoscopy improved from 21.3 (7.4) hours in the pre-BCU era to 9.4 (9.9) hours in BCU, p < 0.001. BCU stay was shorter from 2.41 (1.4) days pre-BCP to 1.93 (1.32) days post-BCP, (p < 0.001). The total hospital stay in pre-BCU (4.0 [2.08] days) as compared to BCU (4.13 [2.62] days; p = 0.58) was similar; there was no impact of BCU on survival. CONCLUSION: A BCU implementation showed improvement in time to UGI endoscopy, and did not reduce BCU stay or impact survival.

A general strategy for regiocontrol in nickel-catalyzed reductive couplings of aldehydes and alkynes.

A strategy for catalyst-controlled regioselectivity in aldehyde-alkyne reductive couplings has been developed. This strategy is the first where either regiochemical outcome may be selected for a broad range of couplings, without relying on substrate biases or directing effects. The complementary use of small cyclopropenylidene carbene ligands or highly hindered N-heterocyclic carbene ligands allows the regiochemical reversal with unbiased internal alkynes, aromatic internal alkynes, conjugated enynes, or terminal alkynes.

Cooperativity of regiochemistry control strategies in reductive couplings of propargyl alcohols and aldehydes.

The nickel-catalyzed reductive coupling of propargyl alcohols and alkynes proceeds with excellent regiochemical control with an underlying electronic preference that can be supplemented by ligand size effects. The products obtained may be readily converted to substructures that are not directly available by an aldehyde-alkyne reductive coupling. A simple model for how steric and electronic factors are both important in governing regiochemistry in couplings of this type is presented, along with examples of how the effects can combine in either a constructive or destructive manner.

Sustained virological response to pegylated interferon and ribavirin in patients with genotype 3 HCV cirrhosis.

BACKGROUND: Chronic hepatitis C (CHC) virus infection in patients with cirrhosis is difficult to treat. There is limited data on the outcome of treatment for genotype 3 HCV infection with cirrhosis. AIMS: To determine sustained virological response (SVR) and its predictive factors in patients with cirrhosis due to genotype 3 HCV infection treated with pegylated interferon and ribavirin (RBV). METHODS: Consecutive patients with compensated cirrhosis due to HCV genotype 3 with positive HCV RNA treated with peg-IFN and RBV in our Gastroenterology Clinics during November 2005 to December 2006 were included in this study. Cirrhosis was diagnosed on the basis of liver biopsy and/or biochemical testing and ultrasound of abdomen. Primary end point of treatment was SVR. RESULTS: Of 66 patients, 32 (48.5%) were male. The mean age was 46.2 +/- 10.1 years; there were 61 (92.4%) patients with Child's A cirrhosis followed by 5 (7.6%) with Child's B type. 33 (50%) patients received pegylated interferon alfa-2a (180 microg/wk) with ribavirin and 33 (50%) received pegylated interferon alfa 2b (1 microg/kg/week) with ribavirin. EVR was achieved in 44 (66.7%), and ETR in 46 (69.7%); overall SVR was achieved in 38 (57.6%) patients. Factors predictive of SVR were age (p value = 0.03), treatment naïve status (p value = 0.04) and EVR (p value < 0.001). Five patients were unable to complete the treatment due to side effects or cytopenias. CONCLUSIONS: Treatment of patients with HCV genotype 3, compensated cirrhosis, with pegylated interferon and ribavirin is effective and well tolerated.

Noninvasive predictors of large varices in patients hospitalized with gastroesophageal variceal hemorrhage.

AIM: To identify noninvasive factors predicting the presence of large varices (LV) in patients hospitalized with gastroesophageal variceal hemorrhage (GEVH). METHODS: Case records of patients admitted with GEVH between January 1998 and June 2005 were retrospectively analyzed. Relevant clinical parameters assessed included Child-Pugh class, ascites (clinical and/or on ultrasound), portosystemic encephalopathy (PSE), splenomegaly (clinical and/or on ultrasound), and hemodynamic instability. The laboratory parameters assessed were hemoglobin level, platelet count, prothrombin time, serum bilirubin, and albumin. The ultrasonographic characteristics noted were splenic size, presence of splenic varices, and portal vein diameter. RESULTS: A total of 420 patients (264 men) presented with GEVH during the study period. The mean age, gender distribution, and presence of cirrhosis were similar in the two groups. Liver cirrhosis with hepatocellular carcinoma (HCC), Child-Pugh class C, presence of clinically detectable ascites, grade 3-4 PSE, detectable splenomegaly, previous history of GEVH, hemodynamic instability and platelet count <91,000 were more common in the LV group. The frequency of radiologically detected ascites, splenomegaly, and portal vein diameter were similar in both groups. On multivariate analysis, the independent predictors for the presence of LV were cirrhosis with HCC, clinically detectable splenomegaly, hemodynamic instability, a previous history of GEVH, platelet count <91,000, and splenic size >/=158 mm. CONCLUSION: Cirrhosis with HCC, clinical splenomegaly, hemodynamic instability, a previous history of GEVH, thrombocytopenia (i.e., platelet count <91,000), and splenic size >/=158 mm are independent noninvasive predictors of large varices in patients hospitalized with gastroesophageal variceal hemorrhage.

Factors predicting in-hospital mortality in patients with cirrhosis hospitalized with gastro-esophageal variceal hemorrhage.

AIM: To identify factors at the time of admission that predict in-hospital mortality in patients with gastro-esophageal variceal hemorrhage. METHODS: Case records of patients admitted with gastro-esophageal variceal hemorrhage between January 1998 and October 2003 were retrospectively analyzed. Relevant clinical and laboratory parameters and their relationship to mortality, were studied. Clinical parameters assessed included Child-Pugh class, ascites, portosystemic encephalopathy (PSE) and occurrence of rebleed within 24 hours of esophago-gastroduodenoscopy. The laboratory parameters assessed were: hemoglobin, prothrombin time, serum bilirubin, creatinine and albumin. RESULTS: Of the 343 patients admitted during the study period, 30 (8.7%) died in hospital. Serum bilirubin (2.4 versus 1.6 mg/dL) and serum creatinine (2.1 vs 1.1 mg/dL) levels were higher among non-survivors than among survivors. Non-survivors were also more likely to suffer from PSE (53%) than survivors (17%), while re-bleeding within 24 hours of endoscopy occurred in 40% and 5% of these groups, respectively. On multivariate analysis, serum creatinine > 1.5 mg/dL at the time of admission (p < 0.001), serum bilirubin > 3 mg/dL (p < 0.001), presence of PSE (p = 0.003) and rebleed within 24 hours of endoscopy (p < 0.001) were significant predictors of mortality. CONCLUSION: Serum creatinine and bilirubin levels, presence of PSE and re-bleeding within 24 hours of initial endoscopy are independent predictors of mortality in patients with gastro-esophageal variceal bleeding.