Objective-Smaller temporal lobe cortical gray matter volumes, including the left superior temporal gyrus, have been reported in magnetic resonance imaging (MRI) studies of patients with chronic schizophrenia and, more recently, in patients with first-episode schizophrenia. However, it remains unknown whether there are progressive decreases in temporal lobe cortical gray matter volumes in patients with first-episode schizophrenia and whether similarly progressive volume decreases are present in patients with affective psychosis.Method-High-spatial-resolution MRI scans at initial hospitalization and 1.5 years later were obtained from 13 patients with first-episode schizophrenia, 15 patients with first-episode affective psychosis (mainly manic), and 14 healthy comparison subjects. MRI volumes were calculated for gray matter of superior temporal gyrus and for the amygdala-hippocampal complex.Results-Patients with first-episode schizophrenia showed significant decreases in gray matter volume over time in the left superior temporal gyrus compared with patients with first-episode affective psychosis or healthy comparison subjects. This progressive decrease was more pronounced in the posterior portion of the left superior temporal gyrus (mean=9.6%) than in the anterior portions (mean=8.4%). No group differences in the rate of change over time were present in other regions.Conclusions-These findings demonstrate a progressive volume reduction of the left posterior superior temporal gyrus gray matter in patients with first-episode schizophrenia but not in patients with first-epiode affective psychosis.Abnormalities in temporal lobe structures, including the superior temporal gyrus and amygdala-hippocampal complex, play a crucial role in dysfunction of auditory and language processing and in memory in patients with schizophrenia (1). Studies of magnetic resonance imaging (MRI) techniques have also demonstrated a gray matter volume reduction in temporal lobe regions of interest, which are associated with auditory hallucinations, thought disorder, and memory dysfunction (see reviews [2][3][4]).Address reprint requests to Dr. McCarley, Department of Psychiatry (116A), Boston VA Healthcare System, Brockton Division, Harvard Medical School, 940 Belmont St., Brockton, MA 02301; robert_mccarley@hms.harvard.edu.. Presented in part at the 39th annual meeting of the Society for Psychophysiological Research, Granada, Spain, Oct. 6-10, 1999, and the 38th annual meeting of the American College of Neuropsychopharmacology, Acapulco, Dec. 12-16, 1999. NIH Public Access Moreover, several investigators have also reported a volume reduction of temporal lobe gray matter regions of interest in patients with first-episode schizophrenia, including the superior temporal gyrus (5,6) and hippocampus (6,7). Our laboratory noted smaller left posterior superior temporal gyrus (8) and smaller left planum temporale and total (left plus right) Heschl's gyri gray matter volumes (9) in patients with first-episode schizophrenia that were not prese...

This study showed that oxidative injuries could be involved in the pathogenesis of AD, as well as indicating that some antioxidant might be associated with the cognitive functions in AD.

Polypeptoids have recently emerged as a subject of scientific interest due to their structural resemblance to existing pseudo-peptidic polymers including poly(αpeptide)s, poly(β-peptide)s, poly(2-oxazoline)s, and poly(Nsubstituted acrylamide)s. With demonstrated backbone degradability, biocompatibility, and thermal processability, polypeptoids are potentially useful in a variety of biotechnological applications. Before those applications can be realized, it is important to develop their synthesis and understand their fundamental properties. In this Perspective, we will review recent advances in the synthesis and characterization of polypeptoids and their copolymers as well as the development of polypeptoid-based functional and structured materials. We will conclude by discussing the future prospects for this nascent class of pseudo-peptidic polymers.

N-Heterocyclic carbene (NHC)-mediated ring-opening polymerization of N-decylN-carboxylanhydride monomer (De-NCA) has been shown to occur in a controlled manner, yielding cyclic poly(N-decyl-glycine)s (c-PNDGs) with polymer molecular weights (MW) between 4.8 and 31 kg·mol−1 and narrow molecular weight distributions (PDI < 1.15). The reaction exhibits pseudo-first order kinetics with respect to monomer concentration. The polymer MW increases linearly with conversion, consistent with a living polymerization. ESI MS and SEC analysesconfirm the cyclic architectures of the forming polymers. DSC and WAXS studies reveal that the c-PNDG homopolymers are highly crystalline with two prominent first order transitions at 72–79°C (Tm,1) and 166–177°C (Tm,2), which have been attributed to the side chain and main chain melting respectively. A series of amphiphilic cyclic diblock copolypeptoids [i.e.,poly(N-methyl-glycine)-b-poly(N-decyl-glycine) (c-PNMG-b-PNDG)] with variable molecular weight and composition was synthesized by sequential NHC-mediated polymerization of the corresponding N-methyl N-carboxyanhydride (Me-NCA) and De-NCA monomers. 1H NMR analysis reveals that adjusting the initial monomer to NHC molar ratio can readily control the block copolymer chain length and composition. Time-lapsed light scattering and cryogenic transmission electron microscopy (cryo-TEM) analysis of c-PNDG-b-PNMG samples revealed that the amphiphilic cyclic block copolypeptoids self-assemble into spherical micelles that reorganize into micron-long cylindrical micelles with uniform diameter in room temperature methanol over the course of several days. An identical morphological transition has also been noted for the linear analogs, which occurs more rapidly than for the cyclic copolypeptoids. We tentatively attribute this difference to the different crystallization kinetics of the solvophobic block (i.e., PNDG) in the cyclic and linear block copolypeptoids.

A series of cyclic and linear poly(N-alkyl glycine)s (a.k.a. polypeptoids) with various linear and branched alkyl side chains (n = 2, 4, 6, 8, 10, 12, and 14) were synthesized by N-heterocyclic carbene or benzylamine-initiated polymerizations of the corresponding N-alkyl N-carboxyanhydride (R-NCAs), respectively. DSC and WAXD studies revealed that cyclic and linear polypeptoids with long linear n-alkyl side chains (n = 4−14) are semicrystalline with two melting transitions attributed to the side chain and main chain crystallization. These crystallizations are strongly coupled: increasing side chain length promotes the side chain crystallization and weakens the main chain crystallization, as evidenced by the increased side chain melting temperature (enthalpy) and the decreased main chain melting temperature (enthalpy) with increasing side chain length. Cyclic and linear polypeptoids bearing alkyl side chains as short as 4 carbons exhibit side chain crystallization at low temperatures (−110 and −117 °C). However, if the side chain crystallization is completely suppressed as in the case of polypeptoids bearing short ethyl groups or asymmetrically branched rac-2-ethyl-1-hexyl groups, the main chain crystallization is also significantly inhibited, further supporting the coupling of the two crystallization events. It was also found that the cyclic polypeptoids exhibit higher main chain melting temperatures relative to the linear counterparts, whereas the side chain melting temperatures are not significantly affected by the polymer architecture. Furthermore, thermal history was shown to affect the polypeptoid crystallization. Annealing above the isotropic temperature followed by cooling significantly enhanced the polymer crystallization, whereas annealing between the two melting temperatures is not effective in promoting crystallization due to the coupling of the side chain and main chain crystallization.