Selective protection and relative importance of the carboxylic acid groups of zaragozic acid A for squalene synthase inhibition.

Chemistry that allows selective modification of the carboxylic acid groups of the squalene synthase inhibitor zaragozic acid A (1) was developed and applied to the synthesis of compounds modified at the 3-,4-,5-,3,4-,3,5-, and 4,5-positions. A key step in this procedure is the selective debenzylation by transfer hydrogenolysis in the presence of other olefinic groups. These compounds were tested in the rat squalene synthase assay and in vivo mouse model. Modification at C3 retains significant enzyme potency and enhances oral activity, indicating that C3 is not essential for squalene synthase activity. Modification at C4 and C5 results in significant loss in enzyme activity. In contrast, substitution at C3 or C4 enhances in vivo activity. Furthermore, disubstitution at the C3 and C4 positions results in additive in vivo potency.

Phosphorylated morpholine acetal human neurokinin-1 receptor antagonists as water-soluble prodrugs.

The regioselective dibenzylphosphorylation of 2 followed by catalytic reduction in the presence of N-methyl-D-glucamine afforded 2-(S)-(1-(R)-(3, 5-bis(trifluoromethyl)phenyl)ethoxy)-3-(S)-(4-fluoro)phenyl-4-(5-(2- phosphoryl-3-oxo-4H,-1,2,4-triazolo)methylmorpholine, bis(N-methyl-D-glucamine) salt, 11. Incubation of 11 in rat, dog, and human plasma and in human hepatic subcellular fractions in vitro indicated that conversion to 2 would be expected to occur in vivo most readily in humans during hepatic circulation. Conversion of 11 to 2 occurred rapidly in vivo in the rat and dog with the levels of 11 being undetectable within 5 min after 1 and 8 mg/kg doses iv in the rat and within 15 min after 0.5, 2, and 32 mg/kg doses iv in the dog. Compound 11 has a 10-fold lower affinity for the human NK-1 receptor as compared to 2, but it is functionally equivalent to 2 in preclinical models of NK-1-mediated inflammation in the guinea pig and cisplatin-induced emesis in the ferret, indicating that 11 acts as a prodrug of 2. Based in part on these data, 11 was identified as a novel, water-soluble prodrug of the clinical candidate 2 suitable for intravenous administration in humans.

Paradoxical autonomic responses to aversive stimuli in the developing rat.

The goals of this research were to determine (a) the change in heart rate elicited by aversive auditory stimuli in the laboratory rat at different ages and (b) the autonomic origins of those changes at each age. The results of the first 2 experiments showed that aversive white noise stimuli elicited cardiac deceleration in preweanling (16-day-old) rats and cardiac acceleration in weanling (23-day-old), periadolescent (30-day-old), and adult (60-day-old) rats. Subsequent experiments showed that (a) the decrease in heart rate elicited by the noise stimulus in preweanling rats was mediated by parasympathetic activation of the heart, (b) the stimulus-elicited increase in heart rate elicited by the noise in periadolescent rats was mediated by parasympathetic withdrawal of the heart, and (c) the noise-induced increase in heart rate in adult rats was primarily mediated by sympathetic activation of the heart.

Comparison of the continuous performance test with and without working memory demands in healthy controls and patients with schizophrenia.

The Penn Continuous Performance Test (PCPT), a measure of sustained visual attention developed for use in functional neuroimaging studies, was compared with a standard CPT developed by Gordon Diagnostic Systems (GDS; Vigilance subtest). The PCPT and the GDS CPT were administered with a standard neuropsychological battery to 68 healthy adults to assess reliability and construct validity. The test had adequate internal consistency, and convergent validity was established through significant correlations between measures of efficiency on the PCPT and the GDS CPT. With the exception of a significant correlation between efficiency measures on the GDS CPT and a measure of auditory sustained attention, neither version of the CPT correlated significantly with other measures in the battery. Factor analysis showed that the PCPT loaded with the GDS CPT. In 39 patients with schizophrenia and 39 matched, healthy controls, equivalent impairment was evident on the two CPT tasks. Neither version correlated significantly with symptom measurements. These results support previous conclusions that sustained visual attention in schizophrenia is a core information processing deficit, not directly related to symptomatology.

Effectiveness of an attention- and memory-training program on neuropsychological deficits in schizophrenia.

The effect of two cognitive remediation procedures developed for closed head injury, Attention Process Training (APT) and Prospective Memory Training (PROMT), on neuropsychological deficits in schizophrenia was investigated. Six patients with schizophrenia, varying in baseline intellectual function and symptoms, were studied; three in a remediation condition and three in a nonremediated control condition. Results were evaluated individually for each of the three treated patients. Two of three remediation-treated subjects showed marked improvement on tests of sustained and divided attention. Untreated patients showed little evidence of change in neuropsychological test performance across a similar time interval, when tested on a subset of the measures administered to remediation-treated patients. The results of this study are discussed with a view toward future studies using larger sample sizes with homogeneous subject populations.

Antecedents of behavior: parents of high-risk newborns.

The Theory of Reasoned Action (Ajzen & Fishbein, 1980) was used to develop an instrument to measure antecedents of parental behavior. The subjects, a convenience sample of 10 parents of high-risk newborns were interviewed 24 to 36 hours after their infant's admission to the neonatal intensive care unit (NICU). Likert and semantic differential scales (Osgood, Suci & Tannenbaum, 1956) were developed based on salient themes identified from the qualitative analysis of the interview transcripts to measure parents': (a) attitudes, (b) social norms, (c) previous experiences and (d) expectations. The instrument was evaluated on 30 parents using a repeated measures design. Results reflect the reliability and validity of the instrument, an emerging model of antecedents of parent's behavior and the presence of differences in antecedents of parent's behavior.

Approaches to cognitive remediation of neuropsychological deficits in schizophrenia: a review and meta-analysis.

A review and critique of the literature pertaining to the use of cognitive remediation techniques in patients with schizophrenia is presented. The review is organized into three sections, according to the neuropsychological deficit targeted for remediation: 1) executive-function, 2) attention, and 3) memory. With regards to executive-function, despite an initial report suggesting that Wisconsin Card Sorting Test performance cannot be remediated, subsequent studies suggest that performance can be improved on a variety of dependent measures including perseverative errors, categories achieved, and conceptual level responses. These observations were confirmed by a meta-analytic investigation that revealed large mean effects sizes (d+ = 0.96) for these studies. Effect sizes were homogenous across discrepant remediation strategies and dependent measures. With regards to attention, serial scanning can be improved with instruction and reinforcement, whereas there is mixed evidence suggesting that practice-based attention drills can improve performance on measures of sustained attention in schizophrenia. With regards to memory, relatively simple semantic and affective elaborate encoding strategies elevates verbal list-learning memory in patients with schizophrenia to levels consistent with controls. A similar encoding procedure, combined with vigilance training, produces substantial improvement in social cue recognition. Avenues for future research are discussed.

Massive production of farnesol-derived dicarboxylic acids in mice treated with the squalene synthase inhibitor zaragozic acid A.

The zaragozic acids are potent inhibitors of squalene synthase. In vivo studies in mice confirmed our earlier observations that inhibition of squalene synthase by zaragozic acid A was accompanied by an increase in the incorporation of label from [3H]mevalonate into farnesyl-diphosphate (FPP)-derived isoprenoic acids (J. D. Bergstrom et al., 1993, Proc. Natl. Acad. Sci. USA 90, 80-84). Farnesyl-diphosphate-derived metabolites appear transiently in the liver. We were unable to detect any farnesol formation in the zaragozic acid-treated animals which indicates that FPP is readily converted to farnesoic acid and dicarboxylic acids in the liver. These metabolites were found to be produced only in the liver and not in the kidney. trans-3,7-Dimethyl-2-octaen-1,8-dioic acid and 3, 7-dimethyloctan-1,8-dioic acid were identified as the major end products of farnesyl-diphosphate metabolism in the urine of mice treated with zaragozic acid A. Quantitative analysis of these FPP-derived dicarboxylic acids by gas-liquid chromatography revealed that approximately 11 mg of total dicarboxylic acids is excreted per day into the urine of a mouse after 3 days of treatment with zaragozic acid A.

Farnesol-derived dicarboxylic acids in the urine of animals treated with zaragozic acid A or with farnesol.

Farnesyl diphosphate, the substrate for squalene synthase, accumulates in the presence of zaragozic acid A, a squalene synthase inhibitor. A possible metabolic fate for farnesyl diphosphate is its conversion to farnesol, then to farnesoic acid, and finally to farnesol-derived dicarboxylic acids (FDDCAs) which would then be excreted in the urine. Seven dicarboxylic acids were isolated by high performance liquid chromatography (HPLC) from urine of either rats or dogs treated with zaragozic acid A or rats fed farnesol. Their structures were determined by nuclear magnetic resonance analysis. Two 12-carbon, four 10-carbon, and one 7-carbon FDDCA were identified. The profile of urinary dicarboxylic acids from rats fed farnesol was virtually identical to that produced by treating with zaragozic acid A, establishing that these dicarboxylic acids are farnesol-derived. By feeding [1-14C]farnesol and comparing the mass of the dicarboxylic acids produced with the ultraviolet absorption of the HPLC peaks, a method to quantitate the ultraviolet-absorbing FDDCAs was devised. When rats were treated with zaragozic acid A, large amounts of FDDCAs were excreted in the urine. The high level of FDDCAs that were found suggests that their synthesis is the major metabolic fate for carbon diverted from cholesterol synthesis by a squalene synthase inhibitor. A metabolic pathway is proposed to explain the production of each of these FDDCAs.

Cognitive impairment and functional status in elderly institutionalized patients with schizophrenia.

OBJECTIVE: The relationship of cognitive impairment to functional status in older adults with schizophrenia was investigated. PATIENTS: Ninety-three psychiatric inpatients with schizophrenia between the ages of 65 and 88 years. Two subsets of this sample, consisting of 48 and 24 patients, were studied with a greater number of assessment instruments. MEASURES: The Mini-Mental State Examination (MMSE) was used for brief assessment of overall cognitive functioning, and the Psychogeriatric Dependency Rating Scale (PGDRS) was administered to assess functional status. The cognitive test battery from the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) and/or an expanded neuropsychological battery, was given to a subset of the patients. RESULTS: In the overall sample, patients with greater global cognitive impairment had higher levels of rated impairment on the individual items that comprised the Orientation and Physical, but not Behavior, subscales of the PGDRS. Furthermore, in the two subsamples, specific neuropsychological measures of problem-solving, word list learning, naming and constructional praxis were related to overall measures of outcome. CONCLUSIONS: Neuropsychological deficit and psychosocial outcome are multi-dimensional entities that relate to one another in complex ways.

2-Aryl indole NK1 receptor antagonists: optimisation of the 2-aryl ring and the indole nitrogen substituent.

Novel 2-aryl indole hNK1 receptor ligands were prepared utilising palladium cross-coupling chemistry of a late intermediate as a key step. Compounds with high hNK1 receptor binding affinity and good brain penetration (e.g., 9d) were synthesised.

Zaragozic acids: a family of fungal metabolites that are picomolar competitive inhibitors of squalene synthase.

Three closely related fungal metabolites, zaragozic acids A, B, and C, that are potent inhibitors of squalene synthase have been isolated and characterized. Zaragozic acids A, B, and C were produced from an unidentified sterile fungal culture, Sporormiella intermedia, and Leptodontium elatius, respectively. The structures of the zaragozic acids and their trimethyl esters were determined by a combination of physical and chemical techniques. The zaragozic acids are characterized by a novel 2,8-dioxobicyclo[3.2.1]octane-4,6,7- trihydroxyl-3,4,5-tricarboxylic acid core and differ from each other in the structures of the 6-acyl and 1-alkyl side chains. They were found to be potent competitive inhibitors of rat liver squalene synthase with apparent Ki values of 78 pM, 29 pM, and 45 pM, respectively. They inhibited cholesterol synthesis in Hep G2 cells, and zaragozic acid A was an inhibitor of acute hepatic cholesterol synthesis in the mouse (50% inhibitory dose of 200 micrograms/kg of body weight). Inhibition of squalene synthase in cells and in vivo was accompanied by an accumulation of label from [3H]mevalonate into farnesyl diphosphate, farnesol, and organic acids. These data indicate that the zaragozic acids are a previously unreported class of therapeutic agents with potential for the treatment of hypercholesterolemia.

2-Aryl indole NK1 receptor antagonists: optimisation of indole substitution.

The synthesis and biological evaluation of a series of 2-aryl indoles with high affinity for the human neurokinin-1 (hNK1) receptor are reported, concentrating on optimisation of the indole substitution.