Engineering the physical parameters for continuous synthesis of fullerene peapods.

Previous efforts to insert fullerenes into a carbon nanotube (CNT) involved the isolated synthesis of CNTs and fullerenes and then annealing CNTs and fullerenes together for encapsulation. We demonstrated the process for the continuous production of fullerene peapods inside the arc instrument by modifying the conventional arc ablation system, which can be repeated to obtain the desired mass scale product. Inside the arc discharge unit, by using the tunable external magnetic field, the double-walled CNTs (DWCNTs) were first synthesized and then directed to deposit onto the water cooled aluminium (Al) plate. The openings were created on DWCNTs by controlled heating of the Al plate and then fullerenes were synthesized and deposited on DWCNTs. In the arc instrument, fullerenes were finally directed to enter into DWCNTs from the defect sites by heating the Al plate in a vacuum. The formation of the peapod was established by the structure-property studies despite the huge deposition of metal catalyst nanoparticles and fullerenes on the surface of the nanotube which were a serious challenge for molecular level characterization of the grown peapod structures.

The role of functional moieties on carbon nanotube surfaces in solar energy conversion.

An easily dispersible multiwalled carbon nanotube (MWCNT) derivative is prepared, and provides a platform for the synthesis of the phenyl butyric acid methyl ester (PCBM) analog. The carbene addition reaction of MWCNTs makes derivatives that are less soluble in organic solvents; by exploiting this differential solubility, PCBM analogs can be separated from the unreacted functionalized MWCNTs. Our experimental evidences indicate that it is the unique properties of the butyric acid methyl ester moiety that makes the acceptor material perform better in organic photovoltaics (OPVs). Studying the combination of the butyric acid methyl ester moiety and the deagglomerated functionalized MWCNT structures provides us an insight into nanoscale charge transfer and transportation inside the donor-acceptor domain. It is demonstrated that a strong structure-property relationship exists for the functionalized MWCNTs, which enables us to correlate the functionality on the carbon nanostructures with performance in OPVs.

A pilot study on the contribution of folate gene variants in the cognitive function of ADHD probands.

Genetic abnormalities in components important for the folate cycle confer risk for various disorders since adequate folate turnover is necessary for normal methylation, gene expression and chromosome structure. However, the system has rarely been studied in children diagnosed with attention deficit hyperactivity disorder (ADHD). We hypothesized that ADHD related cognitive deficit could be attributed to abnormalities in the folate cycle and explored functional single nucleotide polymorphisms in methylenetetrahydrofolate dehydrogenase (rs2236225), reduced folate carrier (rs1051266), and methylenetetrahydrofolate reductase (rs1801131 and rs1801133) in families with ADHD probands (N = 185) and ethnically matched controls (N = 216) recruited following the DSM-IV. After obtaining informed written consent for participation, peripheral blood was collected for genomic DNA isolation and PCR-based analysis of target sites. Data obtained was analyzed by UNPHASED. Interaction between sites was analyzed by the multi dimensionality reduction (MDR) program. Genotypic frequencies of the Indian population were strikingly different from other ethnic groups. rs1801133 "T" allele showed biased transmission in female probands (p < 0.05). Significant difference in genotypic frequencies for female probands was also noticed. rs1801131 and rs1801133 showed an association with low intelligence quotient (IQ). MDR analysis exhibited independent effects and contribution of these sites to IQ, thus indicating a role of these genes in ADHD related cognitive deficit.

Potential contribution of monoamine oxidase a gene variants in ADHD and behavioral co-morbidities: scenario in eastern Indian probands.

Attention deficit hyperactivity disorder (ADHD) is the most frequently diagnosed behavioral disorder in children with a high frequency of co-morbid conditions like conduct disorder (CD) and oppositional defiant disorder (ODD). These traits are controlled by neurotransmitters like dopamine, serotonin and norepinephrine. Monoamine oxidase A (MAOA), a mitochondrial enzyme involved in the degradation of amines, has been reported to be associated with aggression, impulsivity, depression, and mood changes. We hypothesized that MAOA can have a potential role in ADHD associated CD/ODD and analyzed 24 markers in a group of Indo-Caucasoid subjects. ADHD probands and controls (N = 150 each) matched for ethnicity and gender were recruited following the Diagnostic and Statistical Manual for Mental Disorders-IV. Appropriate scales were used for measuring CD and ODD traits. Markers were genotyped by PCR-based methods and data obtained analyzed using the Cocaphase program under UNPHASED. Only eight markers were found to be polymorphic. rs6323 "G" allele showed higher frequencies in ADHD (P = 0.0023), ADHD + CD (P = 0.03) and ADHD + ODD (P = 0.01) as compared to controls. Haplotype analysis revealed statistically significant difference for three haplotypes in ADHD cases (P < 0.02). Statistically significant differences were also noticed for haplotypes in ADHD + CD and ADHD + ODD cases (P < 0.01). LD analysis showed significant variation in different groups. Multidimensionality reduction analysis showed independent as well as interactive effects of markers. Genotypes showed correlation with behavioral problems in ADHD and ADHD + CD. We interpret that MAOA gene variants may contribute to the etiology of ADHD as well as associated co-morbid CD and ODD in this ethnic group.

Immobilization of individual nanotubes in graphitic layers for electrical characterization.

A simple route is followed to produce an abundance of individual carbon nanotubes (CNTs) immobilized in graphitic layers to counter the challenge of locating individual CNTs and restrict the lateral displacement of CNTs due to the high electrostatic force exerted by a scanning tunnelling microscope tip for electrical characterization. Graphitic layers are selected for the embedding matrix as graphite and the nanotubes have a similar work function and hence would not perturb the electrical configuration of the nanotube. Solvent mediated exfoliation of graphite layers to insert the nanotubes was preferred over oxidative expansion, as oxidation could perturb the electrical configuration of graphite. During the exfoliation of graphite the optimized amount of nanotubes was introduced into the medium such that an individual nanotube could be immobilized in few-layer graphene followed by precipitation and centrifugation. The dose and the time of sonication were optimized to ensure that damage to the walls of the nanotubes is minimized, although the ultrasonication causes scissoring of the nanotube length. This procedure for immobilizing nanotubes in graphitic layers would be equally applicable for functionalized CNTs as well. The capability of embedding individual nanotubes into a similar work function material in an organic solvent, which could then be transferred onto a substrate by simple drop casting or spin coating methods, has an added advantage in sample preparation for the STM characterization of CNTs.

A real time analysis of the self-assembly process using thermal analysis inside the differential scanning calorimeter instrument.

The supramolecular assembly of the regioregular poly-3-hexylthiophene (rr-P3HT) in solution has been investigated thoroughly in the past. In the current study, our focus is on the enthalpy of nanofiber formation using thermal analysis techniques by performing the self-assembly process inside the differential scanning calorimetry (DSC) instrument. Thermogravimetric analysis (TGA) was carried out to check the concentration of the solvent during the self-assembly process of P3HT in p-xylene. Ultraviolet visible (UV-vis) spectophotometric technique, small-angle X-ray scattering (SAXS) experiment, atomic force microscopic (AFM), and scanning electron microscopic (SEM) images were used to characterize the different experimental yields generated by cooling the reaction mixture at desired temperatures. Comparison of the morphologies of self-assembled products at different fiber formation temperatures gives us an idea about the possible crystallization parameters which could affect the P3HT nanofiber morphology.

Genetic predisposition to parthenium dermatitis in an Indian cohort due to lower-producing genotypes of interleukin-10 (-) 1082 G>A and (-) 819 C>T loci but no association with interferon-γ (+) 874 A>T locus.

BACKGROUND: Parthenium dermatitis is an activated T cell-mediated type IV hypersensitivity. Its pathogenesis is well characterized, with interindividually varying serum levels of pro- and anti-inflammatory and regulatory T-cell cytokines and coherently perturbed cross-regulation between them. The functional single nucleotide polymorphisms (SNPs) in these cytokine genes might function as risk/susceptibility factors for the disease. OBJECTIVES: We analysed the serum levels of interferon (IFN)-γ and interleukin (IL)-10 cytokines in cases vs. controls and investigated whether IFN-γ (+) 874 A>T and IL-10 (-) 1082 G > A and (-) 819 C>T are associated with serum levels and genetically predispose to the disease. METHODS: The study included 60 patch test-confirmed patients and 60 age- and sex-matched controls. The serum levels of cytokines were estimated by high-sensitivity enzyme-linked immunosorbent assay kits. SNP genotyping was performed by amplification refractory mutational system-polymerase chain reaction. RESULTS: In patients, the serum level of IFN-γ was significantly increased and that of IL-10 was significantly decreased, with no difference in IgE concentration. Genetically no IFN-γ (+) 874 A>T alleles/genotypes were associated with the disease, but a strong predisposition was found due to lower-producing genotypes of IL-10 (-) 1082 G>A and (-) 819 C>T SNPs, with 2·1 and 3·5 times more risk, respectively, while intermediate IL-10-producing genotypes provided resistance. CONCLUSIONS: High serum IFN-γ might play a role in disease pathogenesis, but this is genetically not endowed by the IFN-γ SNP studied. In contrast, low serum IL-10 was very much connected, with the genetics of both studied IL-10 loci. These might be key managing factors concerning pathogenesis/susceptibility.

Prediction of feed intolerance and necrotizing enterocolitis in neonates with absent end diastolic flow in umbilical artery and the correlation of feed intolerance with postnatal superior mesenteric artery flow.

OBJECTIVES: To evaluate the role of postnatal superior mesenteric artery (SMA) flow in predicting feed intolerance and NEC in the babies who had AEDF in comparison with gestation matched SGA and AGA with normal flow. DESIGN: This was a prospective cohort study conducted in 62 eligible babies admitted in NICU. Babies were enrolled in 3 groups. Group 1 (n = 23) was SGA and AEDF, group 2 (n = 20) was SGA and group 3 (n = 19) was AGA and both with normal UA flow. In all babies baseline SMA flow was measured before test feed (0.5 ml) and repeated every 15 minutes for 1 hour after the feed. RESULTS: Feed intolerance was seen in 69.5% of babies in group1 (p = <0.001) as compared to 20% and 17.5% in group 2 and 3. Four (17.3%) babies developed NEC in group1 (p = 0.02) but none in other 2 groups. Baseline peak systolic velocity (PSV) and time average mean velocity (TAMV) at 60 min post feed were significantly (p = 0.01 and 0.028 respectively) lower in group1 than group3. TAMV and PSV at 60 min post feed were significantly lower (p = 0.028 and 0.03) in babies with feed intolerance as compared to no feed intolerance group. Absent end diastolic flow and hypoglycemia were independent risk factors for feed intolerance. CONCLUSION: SGA babies with AEDF had higher incidence of feed intolerance and NEC. Serial SMA flow studies specially the 60 min post feed study may help in differentiating which babies are likely to develop feed intolerance.

Clinical risk factors associated with extubation failure in ventilated neonates.

We conducted this study to find out the incidence of extubation failure (EF) in ventilated neonates and associated clinical risk factors. Eighty two ventilated neonates were followed up to 48 hours post extubation to look for EF. Twenty two babies (26.8%) had EF. The common risk factors for EF were presence of patent ductus arteriosus, post-extubation lung collapse and acquired pneumonia. The duration of ventilation, and maximum and pre-extubation alveolar arterial oxygen gradients (AaDO2) were significantly higher (P<0.05) in EF group. The incidence of sepsis (P=0.034), anemia (P=0.004) and pneumonia (P=0.001) were significantly higher in EF group. Detection of significant PDA and adequate post extubation care may help to reduce rate of extubation failure in neonates.

Radionuclide scintigraphy in the evaluation of gastroesophageal reflux in symptomatic and asymptomatic pre-term infants.

PURPOSE: Gastroesophageal reflux (GER) is very common in pre-term infants. The diagnosis based on symptoms is always questionable. The incidence of GER in symptomatic babies varies from 22% to 85%, but literature regarding the incidence of reflux in asymptomatic pre-term infants is lacking. We used radionuclide scintigraphy to evaluate the incidence of GER in symptomatic as well as asymptomatic pre-term neonates and to assess whether symptoms have any relation with positive scintigraphy. METHODS: We studied 106 pre-term infants (52 symptomatic, 54 asymptomatic) of less than 34 weeks of gestation, who fulfilled the eligibility criteria. Babies were considered symptomatic in the presence of vomiting, regurgitation, apnea, de-saturations, unexplained bradycardia and recurrent lung collapses. Radionuclide scintigraphy was conducted at post-conceptional age of 32-34 weeks when they were clinically stable for 72 h. Feeding was avoided for 2 h preceding the study. (99m)Tc sulphur colloid was administered in a dose of 1.85 MBq (0.05 mCi) in 1 ml, followed by milk (full feed) through an orogastric tube, prior to imaging under a gamma camera. Reflux was graded as low or high, and reflux episodes during the study were counted. RESULTS: The incidence of GER in the symptomatic group was 71.2% and in asymptomatic babies 61.1% (p = 0.275). High-grade reflux was more common (71.4%) than low-grade (28.6%) in both groups (p = 0.449). Mean number of reflux episodes in 20 min was 4.4 +/- 2.4 in symptomatic babies and 4.9 +/- 2.2 in asymptomatic babies (p = 0.321). Babies with positive scintigraphy were similar in birth weight, gestation, time to achieve full feeds, weight and age at discharge to those with negative scintigraphy. CONCLUSIONS: GER is common in pre-term infants of less than 34 weeks gestation. The incidence of positive scintigraphy and grade of reflux is not significantly different in symptomatic vs. asymptomatic babies. Though radionuclide scintigraphy is a simple, quick and non-invasive investigation in suspected cases of GER, positive scintigraphy has no correlation with symptoms.

Effect of cholesterol on interaction of dibucaine with phospholipid vesicles: a fluorescence study.

Interaction of the local anesthetic dibucaine with small unilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) and dioleoyl phosphatidylcholine (DOPC) containing different mol percents of cholesterol has been studied by fluorescence spectroscopy. Fluorescence measurements on dibucaine in presence of phospholipid vesicles containing various amounts of cholesterol yielded a pattern of variation of wavelength at emission maximum and steady-state anisotropy which indicated that the microenvironment of dibucaine is more polar and flexible in membranes that contain cholesterol than in membranes without cholesterol. Experiments on quenching of fluorescence from membrane-associated dibucaine by potassium iodide showed a marked increase in quenching efficiency as the cholesterol content of the vesicles was increased, demonstrating increased accessibility of the iodide quenchers to dibucaine in the presence of cholesterol, when compared to that in its absence. Total emission intensity decay profiles of dibucaine yielded two lifetime components of approximately 1 ns and approximately 2.8--3.1 ns with mean relative contributions of approximately 25 and approximately 75%, respectively. The mean lifetime in vesicles was 20--30% smaller than in the aqueous medium and showed a moderate variation with cholesterol content. Fluorescence measurements at two different temperatures in DMPC SUVs, one at 33 degrees C, above the phase transition temperature and another at 25 degrees C, around the main phase transition, indicated two different mode of dibucaine localization. At 25 degrees C dibucaine partitioned differentially in presence and absence of cholesterol. However, at 33 degrees C the apparent partition coefficients remained unaltered indicating differences in the microenvironment of dibucaine in presence and absence of cholesterol in the phospholipid membranes.

Separation of carrier-free 181Re produced in 16O-irradiated thulium target.

Heavy ion activation of natural Tm2O3 with 90 MeV 16O beam results in the formation of carrier-free short-lived 181Ir and 181Os which ultimately decay out to 181Re in the matrix. The liquid cation exchanger, HDEHP, has effectively been utilized as an extractant for quantitative separation of bulk thulium target matrix from carrier-free rhenium radionuclide.

Overexpression of DeltaFosB transcription factor(s) increases bone formation and inhibits adipogenesis.

Members of the AP-1 family of transcription factors participate in the regulation of bone cell proliferation and differentiation. We report here a potent AP-1-related regulator of osteoblast function: DeltaFosB, a naturally occurring truncated form of FosB that arises from alternative splicing of the fosB transcript and is expressed in osteoblasts. Overexpression of DeltaFosB in transgenic mice leads to increased bone formation throughout the skeleton and a continuous post-developmental increase in bone mass, leading to osteosclerosis. In contrast, DeltaFosB inhibits adipogenesis both in vivo and in vitro, and downregulates the expression of early markers of adipocyte differentiation. Because osteoblasts and adipocytes are thought to share a common precursor, it is concluded that DeltaFosB transcriptionally regulates osteoblastogenesis, possibly at the expense of adipogenesis.

Granulocyte macrophage-colony stimulating factor (GM-CSF) in neonatal neutropenia.

Neutropenia in neonates is often associated with sepsis, prematurity and maternal hypertension with increased risk of mortality. We describe two neonates with neutropenia treated with granulocyte macrophage colony stimulating factor. The total and absolute neutrophil counts showed a marked response and led to a favourable outcome. Human granulocyte macrophage colony stimulating factor may be used as an adjuvant therapy for neonatal neutropenia of different aetiologies.

Use of RNA arbitrarily primed-PCR fingerprinting to identify Vibrio cholerae genes differentially expressed in the host following infection.

Evidence suggests that a repertoire of Vibrio cholerae genes are differentially expressed in vivo, and regulation of virulence factors in vivo may follow a different pathway. Our work was aimed at characterization of in vivo-grown bacteria and identification of genes that are differentially expressed following infection by RNA arbitrarily primed (RAP)-PCR fingerprinting. The ligated rabbit ileal loop model was used. The motility of in vivo-grown bacteria increased by 350% over that of in vitro-grown bacteria. Also, the in vivo-grown cells were more resistant to killing by human serum. By using the RAP-PCR strategy, five differentially expressed transcripts were identified. Two in vitro-induced transcripts encoded polypeptides for the leucine tRNA synthatase and the 50S ribosomal protein, and the three in vivo-induced transcripts encoded the SucA and MurE proteins and a polypeptide of unknown function. MurE is a protein involved in the peptidoglycan biosynthetic pathway. The lytic profiles of in vivo- and in vitro-grown cells suspended in distilled water were compared; the former was found to be slightly less sensitive to lysis. Ultrathin sections of both cells observed under the transmission electron microscope revealed that in contrast to the usual wavy discontinuous membrane structure of the in vitro-grown cells, in vivo-grown cells had a more rigid, clearly visible double-layered structure. The V. cholerae murE gene was cloned and sequenced. The sequence contained an open reading frame of 1,488 nucleotides with its own ribosome-binding site. A plasmid containing the murE gene of V. cholerae was transformed into V. cholerae 569B, and a transformed strain, 569BME, containing the plasmid was obtained. Ultrathin sections of 569BME viewed under a transmission electron microscope revealed a slightly more rigid cell wall than that of wild-type 569B. When V. cholerae 569B and 569BME cells were injected separately into ligated rabbit ileal loops, the transformed cells had a preference for growth in the ileal loops versus laboratory conditions.

The tyrosine phosphatase SHP-1 is a negative regulator of osteoclastogenesis and osteoclast resorbing activity: increased resorption and osteopenia in me(v)/me(v) mutant mice.

Naturally occuring inactivating mutations of the Src homology 2 (SH2) domain-containing tyrosine phosphatase 1 (SHP-1) in mice give rise to the motheaten (me) phenotype. me/me mice have multiple hematopoietic abnormalities, suggesting that this phosphatase plays an important role in hematopoiesis. SHP-1 binds to and is activated by several hematopoietic surface receptors, including the colony-stimulating factor type 1 receptor. We have examined the role of SHP-1 in osteoclastogenesis and osteoclast function using mice with the viable motheaten (me(v)/me(v)) mutation, which has markedly decreased SHP-1 activity. Histomorphometric analysis of 6-week-old me(v)/me(v) mice and control littermates showed a marked osteopenia with an increase in bone resorption indices. The number of formed osteoclast-like cells (OCLs) in cocultures of me(v)/me(v) hematopoietic cells with normal osteoblasts was significantly increased. In contrast, the number of OCLs formed in the coculture of normal bone marrow cells with the me(v)/me(v) osteoblasts was not significantly different from controls. The bone-resorbing activity of me(v)me(v) OCLs and authentic osteoclasts was also found to be increased. Finally, Western blotting of proteins from me(v)/me(v) and control OCLs revealed an overall increase in tyrosine phosphorylation in the me(v)/me(v) lysates. These in vivo and in vitro results suggest that SHP-1 is a negative regulator of bone resorption, affecting both the formation and the function of osteoclasts.

Sequential search and the influence of male quality on female mating decisions.

The patterns of phenotypic association between mated males and females depend on the decision rules that individuals employ during search for a mate. We generalize the sequential search rule and examine how the shape of the function that relates a male character to the benefit of a mating decision influences the threshold value of the male trait that induces females to terminate search. If the fitness function is linear the optimal threshold value of a male character increases with the slope of the function. The phenotypic threshold criterion declines, all else being equal, if the fitness function is made more concave (or less convex) by an increase of the risk of the function. The expression of the trait in females has no effect on the optimal threshold value of a male character if the fitness function is linear and phenotypic values combine additively to influence the benefit of a mating decision; the phenotypic threshold criterion is ubiquitous among females. A convex fitness function induces females with high trait values to adopt a relatively high phenotypic threshold criterion, whereas a concave fitness function induces such females to adopt a low threshold value for the male trait. Thus, linear, convex and concave fitness functions effect random, assortative and disassortative combinations of phenotypes among mated individuals, respectively. Changes of female search behavior induced by changes of the distribution of a male character similarly depend on the shape of the fitness function. A variance-preserving increase of male trait values produces a relatively small increase of the threshold criterion for the male character if the fitness function is concave, relative to conditions in which the fitness function is either linear or convex. Our results suggest that a sequential search rule can in principle induce the kinds of mating patterns observed in nature and that the phenotypic association between mated individuals is likely to depend on how a male character translates into fitness, the distribution of the trait among males and attributes of searching females.

Conformation induction in melanotropic peptides by trifluoroethanol: fluorescence and circular dichroism study.

Conformation induction in the two related peptides, alpha-melanocyte stimulating hormone (alpha-MSH) and delta-melanocyte stimulating hormone (delta-MSH), have been studied in solvent media containing varying percentages of the membrane-mimetic solvent 2,2,2-trifluoroethanol (TFE) using fluorescence and circular dichroism (CD) spectroscopy. Singular value decomposition (SVD) analysis of the CD spectra at different TFE concentrations showed that these spectra can be described as linear combinations of only two distinct basis spectra, corresponding to the peptides in the random-coil and 'folded' conformations. For alpha-MSH the spectrum of the folded state is very similar to the standard spectrum of the alpha-helix, while that for delta-MSH has partial resemblance to the helical spectrum. Fitting the data on ellipticity (at 222 nm) as a function of TFE volume fraction to an equation based on a two-state model describing TFE-induced conformation induction in the peptides gave values of (1.1 +/- 0.4) and (4.2 +/- 0.5) kcal mol-1 for alpha-MSH and delta-MSH, respectively, for the free energy of equilibrium between the helix and coil forms in water. Measurement of fluorescence emission parameters (emission maximum, quantum yield, steady-state anisotropy and mean excited-state lifetime) indicated that the microenvironment around the single tryptophan residues of both peptides changes in like manner with increasing concentration of TFE in the solvent. The similarity of fluorescence behaviour of the peptides suggests that their Trp fluorophores do not participate in secondary structure formation in TFE.