The objective of this study was to evaluate how enrichment for responders increases assay sensitivity in an enriched enrollment randomized withdrawal (EERW) proof-of-concept (POC) study in neuropathic pain. Adults with moderate to severe peripheral neuropathic pain entered a 3- to 4-day screening period, followed by a 12-day titration to the highest tolerated dose that provided pain control (pregabalin 50-200mg t.i.d.), and then a 9-day maintenance period. Subjects were stratified as primary responders (⩾30%), secondary responders (⩾10% to <30%), or nonresponders (<10%) based on decrease in pain intensity and were randomized to placebo or pregabalin during the randomized withdrawal period. The primary endpoint was mean of average 24-h pain intensity during the last 3days of treatment period relative to the 3days before randomization. Time-to-efficacy-failure was the key secondary endpoint. Other features included not requiring discontinuation of current analgesic therapies and blinding investigators to study design elements that could contribute to non-treatment-related responses. Effect size (ES) (mean treatment difference/SD) was used to measure assay sensitivity. Pregabalin-treated subjects (n=52) had significantly less pain than those receiving placebo (n=51) (P⩽.003). Effect size of the primary endpoint was 0.72 for primary responders and decreased if secondary and nonresponders were included in the analysis. The highest ES (1.68) was demonstrated for the endpoint time-to-efficacy-failure seen in primary responders with painful diabetic neuropathy. The EERW trial design using time-to-efficacy-failure may provide a sensitive and efficient method to conduct POC studies of novel therapies in patients with neuropathic pain. Enriching a study population with patients who have achieved a 30% decrease in pain with an investigational therapy, and using time-to-efficacy-failure during the randomized withdrawal phase as the primary endpoint, can be used for a proof-of-concept study to optimize assay sensitivity and efficiently determine the analgesic potential of a new treatment for neuropathic pain.
The mammalian aminoadipic semialdehyde synthase is a bifunctional enzyme that catalyzes the first two sequential steps in lysine degradation in the major saccharopine pathway (Markovitz, P.
The rapid-cycling variant of bipolar disorder constitutes about 15%-20% of all bipolar patients, and 72%-82% of these patients exhibit less than adequate response to lithium therapy. Valproate's spec- trum of efficacy was examined in 78 patients with rapid-cycling bipolar disorder in a prospective, open, 15.8-month trial. Thirty patients received valproate monotherapy and 48 received combination therapy. Treatment assignment was nonrandomized and based on prior treatment history. A marked acute response was seen in 54% of the patients with mania, 87% of those with mixed states, and 19% of those with depression. Marked prophylactic responses were seen in 72% of manic patients, 94% of mixed states patients, and 33% of depressed patients. In addition, moderate acute antimanic responses were observed in another 31% of the patients, prophylactic antimanic responses in 17%, acute antimixed state responses in 0%, prophylactic antimixed state responses in 0%, acute antidepressant responses in 25%, and prophylactic antidepressant responses in mixed states in 34%. Pattern analysis was conducted to examine the spectrum of efficacy of valproate in various cells (e.g., the cohort of patients who had an acute antimanic response to the drug). Pattern analysis showed that 40% of the patients with a marked prophylactic antimanic response had a marked antidepressant response to valproate. However, among the patients with a marked antidepressant response to valproate, 91% had a marked antimanic response. The most common side effects of valproate in our study, as in earlier studies, were gastrointestinal problems (nausea, stomach cramps, diarrhea), tremors, lethargy, and hair thinning. Life charting techniques disclosed a bimodal distribution of episode frequencies, with the first mean approximating 10 episodes per year and the second estimated at 30 per year or too numerous to count. Consistent with previous observations, our data suggest that valproate has marked antimanic efficacy, minimal to moderate antidepressant properties, and marked antimixed state efficacy.
Familial hyperlysinemias are autosomal recessive disorders in the oxidative degradation of lysine. Hyperlysinemia type I is associated with a combined deficiency in lysine-ketoglutarate reductase and saccharopine dehydrogenase activities, the first two sequential steps in the lysine degradative pathway. In familial hyperlysinemia type II, only saccharopine dehydrogenase activity is deficient. We report here that these reductase and dehydrogenase activities occur on a single protein based on the following findings. (i) The activity ratio of reductase/dehydrogenase remained constant (close to unity) throughout a 500-fold purification of both enzyme activities from mitochondrial extracts of baboon and bovine livers. The activity profiles of the reductase and the dehydrogenase superimpose on each other as the enzyme was eluted from DEAE-cellulose and Sephacryl S-300 columns. (ii) Activity-staining of the native polyacrylamide gel showed that both activities migrated the same distance toward the anode. (iii) The highly purified enzyme with the reductase and dehydrogenase activities showed a single polypeptide band of Mr = 115,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native enzyme from baboon and bovine livers has an apparent Mr of 468,000 (Stokes radius = 69.5 A) as determined by gel filtration, which suggests a tetrameric structure of identical subunits. The presence in mammalian tissues of a single protein catalyzing both the reductase and dehydrogenase reactions explains the combined enzyme deficiency observed in hyperlysinemia type I. We propose that the bifunctional enzyme be called aminoadipic semialdehyde synthase.
Limited proteolysis has been used to probe the subunit structure (M, = 52,000) of the dihydrolipoyl transacylase (E2) component of the branched-chain aketo acid dehydrogenase complex from bovine liver.Digestion of the complex at 0 OC with a low concentration of trypsin produces an inner E2 core that retains the activity for the transacylation reaction and is completely dissociated from the decarboxylase (El) component.The trypsinized E2 maintains the highly assembled structure and migrates faster than the native E2 in the Sepharose 4B column.Sodium dodecyl sulfatepolyacrylamide gel electrophoresis shows that the inner Ez core consists of two lipoate-free tryptic fragments, Le. fragment A and fragment B with M, = 26,000 and 22,000, respectively.Both fragments apparently fail to bind the El component.Fragment A is converted into fragment B by increasing trypsin concentrations.Fragment B is a stable limit polypeptide containing the intersubunit-binding sites for E2.The assemblage of fragment B confers the cubelike appearance of the inner E2 core in electron micrographs.Activity measurements indicate that the larger fragment A, but not fragment B, possesses transacylation activity.It is likely that a critical portion of the active site is present in the 4,000-dalton fragment that is lost during the conversion of fragment A to B.The branched-chain a-keto acid dehydrogenase complex catalyzes oxidative decarboxylation of the a-keto acids comprising a-ketoisovalerate, a-ketoisocaproate, and a-keto-pmethylvalerate through Reaction 1.The multienzyme complex R-CO-COOH + CoASH + NAD+ Msp' R-CO-S-CoA (1)
Gene expression profiles in blood are increasingly being used to identify biomarkers for different affective disorders. We have selected a set of 29 genes to generate expression profiles for healthy control subjects as well as for patients diagnosed with acute post-traumatic stress disorder (PTSD) and with borderline personality disorder (BPD). Measurements were performed by quantitative polymerase chain reaction (qPCR). Using the actual data in an anonymous form we constructed a series of artificial data sets with known gene expression profiles. These sets were used to test 14 classification algorithms and feature selection methods for their ability to identify the correct expression patterns. Application of the three most effective algorithms to the actual expression data showed that control subjects can be distinguished from BPD patients based on differential expression levels of the gene transcripts Gi2, GR and MAPK14, targets that may have links to stress related diseases. Controls can also be distinguished from acute PTSD patients by differential expression levels of the transcripts for ERK2 and RGS2 that are known to be associated with mood disorders and social anxiety. We conclude that it is possible to identify informative transcription profiles in blood samples from individuals with affective disorders.
