Nanotube transistors as direct probes of the trap dynamics at dielectric-organic interfaces of interest in organic electronics and solar cells

The high sensitivity of nanotube transistors is used for the first time as a probe to study charge dynamics at a dielectric/polymer (polythiophene) interface, an inorganic/organic junction of particular importance for organic solar cells, and organic field effect transistors (OFETs). A carbon nanotube field effect transistor is coated with a thin film of a photoconductive polymer and photoexcited so as to generate carriers in the structure. Comparison between devices using SiO2 and TiO2 as gate dielectric reveals the critical role of the dielectric and clearly elucidates the relative contributions of the polymer and the dielectric layers on the separation, trapping, and relaxation of photogenerated charges.     

Conical and biconical ultra-high-Q optical-fiber nanowire microcoil resonator

New 3D geometries of the optical nanowire microcoil resonator are suggested and investigated theoretically. The dependence of the Q factor on coupling parameters is calculated and compared for three different profiles. Results suggest that ultra-high-Q resonators can be fabricated more easily when the nanowire microcoil resonator has a biconical profile.     

Proinflammatory cytokines regulate antigen-independent T-cell activation by two separate calcium-signaling pathways in multiple sclerosis patients

OBJECTIVE: The study examined the prevalence of low birth weight among biracial infants of black and white parents, by region of the United States. METHODS: Using the national linked live birth-death infant file for 1991, low birth weight (<2,500 g) was examined among 50,980 biracial singleton infants according to parental race (black mother-white father vs. white mother-black father). RESULTS: Nationally, the rate of low birth weight was 31% higher in the black mother-white father group (8.4%) than in the white mother-black father group (6.4%). The difference was smaller in the Northeast, reflecting a high rate (9.8%) for biracial infants of Puerto-Rican white mothers. The difference in the West was larger (75%), due to both a high rate in the black mother-white father group (9.1%) and a low rate for the white mother-black father group (5.2%), and persisted after controlling for parental education and a variety of maternal risk factors. CONCLUSIONS: Further studies are needed to identify the maternal factors involved in the regional differences in the prevalence of low birth weight among biracial infants.     

Antitumor activity of bax and p53 naked gene transfer in lung cancer: in vitro and in vivo analysis

In vitro and in vivo data have demonstrated that virus-mediated p53 gene transfer can induce active cell death and lung tumor regression. In contrast, the therapeutic potential of bax, another apoptosis-inducing gene, has not been described. We compared p53 and bax cytotoxic effects by transient transfection of an average of 25 +/- 5% of the H-322 and H-358 bronchioloalveolar carcinoma cell lines in vitro. Under these conditions, bax expression killed 70 to 90% of the transfected cells whereas p53 killed only 40% of them. The killing activity of both genes involved apoptosis, as shown by TUNEL staining. Surprisingly, BrdU incorporation indicated that the cells that did resist Bax toxicity were blocked in the pre-S phase of the cell cycle, a result expected for p53 only. In vivo, repeated injections of naked DNA encoding Bax or p53 inhibited the growth of 4-mm preestablished H-322 tumors in nude mice. Growth retardation only, and not inhibition, was observed in H-358, a poorly transfectable and rapidly growing tumor. These results indicate that Bax and p53 share a similar, strong antitumor activity in vivo, even if the former is a more potent inducer of apoptosis in vitro.     

The N-terminal globular domain of Eph receptors is sufficient for ligand binding and receptor signaling

The Eph family of receptor protein-tyrosine kinases (RTKs) have recently been implicated in patterning and wiring events in the developing nervous system. Eph receptors are unique among other RTKs in that they fall into two large subclasses that show distinct ligand specificities and for the fact that they themselves might function as 'ligands', thereby activating bidirectional signaling. To gain insight into the mechanisms of ligand-receptor interaction, we have mapped the ligand binding domain in Eph receptors. By using a series of deletion and domain substitution mutants, we now report that an N-terminal globular domain of the Nuk/Cek5 receptor is the ligand binding domain of the transmembrane ligand Lerk2. Using focus formation assays, we show that the Cek5 globular domain is sufficient to confer Lerk2-dependent transforming activity on the Cek9 orphan receptor. Extending our binding studies to other members of both subclasses of receptors, it became apparent that the same domain is used for binding of both transmembrane and glycosylphosphatidyl-anchored ligands. Our studies have determined the first structural elements involved in ligand-receptor interaction and will allow more fine-tuned genetic experiments to elucidate the mechanism of action of these important guidance molecules.     

Plasma prolactin response to D-fenfluramine is blunted in bulimic patients with frequent binge episodes

BACKGROUND: Abnormalities of brain serotonin (5-HT) transmission have been implicated in the pathophysiology of bulimia nervosa (BN), but no conclusive data have yet been provided. The purpose of this study was to assess 5-HT transmission via the measurement of the prolactin (PRL) response to the specific 5-HT releasing agent D-fenfluramine (D-FEN) in both patients with BN and comparison subjects. METHODS: According to a double-blind placebo-controlled design, plasma PRL response to D-FEN was measured in 14 drug-free bulimics and 14 matched healthy controls. In both patients and controls, eating-related psychopathology, depressive and obsessive-compulsive symptoms, and aggressiveness were measured by rating scales. RESULTS: Baseline plasma levels of PRL and 17 beta-oestradiol were significantly reduced in bulimic patients, whereas basal plasma levels of cortisol did not significantly differ from healthy controls. PRL response to D-FEN was not different between patients and controls as groups, but it was significantly blunted in bulimics with high frequency bingeing (> or = 2 binge episodes per day; N = 7) as compared to both those with low frequency bingeing (< or = 1 binge episode per day; N = 7) and matched controls. A significant negative correlation emerged between the frequency of binge episodes and the hormone response to D-FEN. Moreover, although patients scored higher than healthy subjects on rating scales assessing depressive and obsessive-compulsive symptoms and aggressiveness, no significant correlation was found between these measures and the PRL response to D-FEN. CONCLUSIONS: These results support the idea that serotonin transmission is impaired in bulimic patients with frequent binge episodes.     

Characterization of furazolidone apical-related effects to human polarized intestinal cells

Neuron numbers in developing vertebrate organisms are regulated by the availability of growth factors which promote their survival. However, neuron survival may also be regulated by growth factors which promote rather than prevent cell death. This study examined the effects of bone morphogenetic proteins (BMPs) in inducing apoptosis of MAH cells, an immortalized sympathoadrenal progenitor cell line. Treatment of MAH cells with BMP2 or BMP4 killed the cells in a dose-dependent manner. By contrast, treatment with BMP7 or TGFbeta1 failed to affect survival, suggesting that induction of apoptosis is specific to the dpp subgroup of BMPs. Survival after treatment with BMP2 or BMP4 required addition of fibroblast growth factor (FGF) and nerve growth factor (NGF), indicating that BMP treatment made the neurons dependent upon an exogenous factor for survival. Several experimental observations suggested an apoptotic mechanism for BMP-induced death. After BMP2 treatment, the cells progressively shrank and became pyknotic. Further, there was prominent endonucleosomic cleavage of DNA (laddering) as well as TUNEL staining. Moreover, BMP-induced death was inhibited by the caspase inhibitor z-VAD and was partially prevented by the endonuclease inhibitor aurintricarboxylic acid. These observations suggest that neuron numbers may be regulated by factors which promote death and that exposure to such factors may be a signal for the development of dependence upon other growth factors for survival.     

Influence of breast- and formula-feeding on plasma cholesterol precursor sterols throughout the first year of life

We evaluated endogenous cholesterol synthesis and plasma lipid profile longitudinally from birth to 1 year old in infants who were exclusively breast-fed (n = 19) or formula-fed (n = 19) for the first 4 months of life. At 1 and 4 months of age, breast-fed infants had higher plasma total and low-density lipoprotein cholesterol and apolipoprotein B levels than formula-fed infants, whereas plasma mevalonate and lanosterol levels were not different between the two study groups.     

Comparison of molecular changes in lung cancers in HIV-positive and HIV-indeterminate subjects

CONTEXT: Human immunodeficiency virus (HIV) infection has been associated with an increasing incidence of malignancy, and HIV-infected persons have an increased incidence of primary lung carcinoma compared with the general population. OBJECTIVE: To investigate the molecular changes present in HIV-associated lung tumors and compare them with those present in lung carcinomas arising in HIV-indeterminate subjects ("sporadic tumors"). DESIGN: Convenience sample. SUBJECTS: Archival tissues from 11 HIV-positive persons and from 35 persons of indeterminate HIV status. SETTING: University-based medical centers and affiliated hospitals. MAIN OUTCOME MEASURES: Analysis of frequency of loss of heterozygosity (LOH) and microsatellite alteration (MA) using polymerase chain reaction and 16 polymorphic microsatellite markers at 8 chromosomal regions frequently deleted in lung cancer. Presence of HIV and human papillomavirus (HPV) sequences. RESULTS: The overall frequency of LOH at all chromosomal regions tested and the frequencies at most of the individual regions were similar in the 2 groups. Frequency of MA present in the HIV-associated tumors (0.18) was 6-fold higher than in sporadic tumors (0.03) (P<.001). At least 1 MA was present in 10 (91%) of 11 HIV-associated tumors vs 17 (48%) of 35 sporadic tumors (P=.02). Molecular changes were independent of tumor stage and gender. HIV and HPV sequences were not detected in the HIV-associated lung carcinomas. CONCLUSIONS: Microsatellite alterations, which reflect widespread genomic instability, occur at greatly increased frequency in HIV-associated lung carcinomas. Although the mechanism underlying the development of increased MAs is unknown, it may play a crucial role in the development of many HIV-associated tumors.