A relationship between mechanically-induced changes in serum cartilage oligomeric matrix protein (COMP) and changes in cartilage thickness after 5 years

OBJECTIVE

To evaluate the hypothesis that a mechanical stimulus (30-min walk) will produce a change in serum concentrations of cartilage oligomeric matrix protein (COMP) that is associated with cartilage thickness changes on magnetic resonance imaging (MRI).

METHODS

Serum COMP concentrations were measured by enzyme-linked immunosorbent assay in 17 patients (11 females, age: 59.0±9.2 years) with medial compartment knee osteoarthritis (OA) at study entry immediately before, immediately after, 3.5 h, and 5.5 h after a 30-min walking activity. Cartilage thickness changes in the medial femur and medial tibia were determined from MR images taken at study entry and at 5-year follow-up. Relationships between changes in cartilage thickness and COMP levels, with post-activity concentrations expressed as a percentage of pre-activity levels, were assessed by the calculation of Pearson correlation coefficients and by multiple linear regression analysis, with adjustments for age, sex, and body mass index (BMI).

RESULTS

Changes in COMP levels 3.5 h and 5.5 h post-activity were correlated with changes in cartilage thickness in the medial femur and tibia at the 5-year follow-up. The results were strengthened after analyses were adjusted for age, sex, and BMI. Neither baseline pre-activity COMP levels nor changes in COMP levels immediately post-activity were correlated with cartilage thickness changes.

CONCLUSIONS

The results of this study support the hypothesis that a change in COMP concentration induced by a mechanical stimulus is associated with cartilage thinning at 5 years. Mechanically-induced changes in mechano-sensitive biomarkers should be further explored in the context of stimulus-response models to improve the ability to assess OA progression.

Chemotherapy dose-intensity and survival for childhood medulloblastoma

AIM

To determine the relationship between prescribed dose-intensity of chemotherapy and survival in childhood medulloblastoma.

MATERIALS AND METHODS

A total of 55 trials from 1970-2009 were identified, 30 were eligible for analysis, with individual treatment regimes with 5-year (or more) outcome figures. Relationships of outcome to dose-intensity were analysed using weighted regression.

RESULTS

Overall, 2,434 patients were identified, 1,010 were classified as 'standard'- and 671 as 'high'-risk patients, with 5-year overall survivals (OS) of 67.2% (95% Confidence Interval=60.5%-73.6%) and 47.6% (95% Confidence Interval=39.5%-55.7%), respectively. A protective effect for chemotherapy versus craniospinal radiotherapy alone (5-year OS of 58.2% versus 51.6%) was found. Individually, vincristine, cisplatin, lomustine (CCNU) and cyclophosphamide appear to confer the most beneficial effect, particularly for high-risk patients. Positive relationships between OS and dose-intensity were found, except for lomustine, with cyclophosphamide offering the greatest protection.

CONCLUSION

Consideration of chemotherapy dose-intensity may further optimise treatment, particularly in the context of risk stratification.

Economic analysis of Mycobacterium avium subspecies paratuberculosis vaccines in dairy herds

Johne's disease, or paratuberculosis, is a chronic infectious enteric disease of ruminants, caused by infection with Mycobacterium avium ssp. paratuberculosis (MAP). Given the absence of a fail-safe method of prevention or a cure, Johne's disease can inflict significant economic loss on the US dairy industry, with an estimated annual cost of over $200 million. Currently available MAP control strategies include management measures to improve hygiene, culling MAP serologic- or fecal-positive adult cows, and vaccination. Although the 2 first control strategies have been reported to be effective in reducing the incidence of MAP infection, the changes in herd management needed to conduct these control strategies require significant effort on the part of the dairy producer. On the other hand, vaccination is relatively simple to apply and requires minor changes in herd management. Despite these advantages, only 5% of US dairy operations use vaccination to control MAP. This low level of adoption of this technology is due to limited information on its cost-effectiveness and efficacy and some important inherent drawbacks associated with current MAP vaccines. This study investigates the epidemiological effect and economic values of MAP vaccines in various stages of development. We create scenarios for the potential epidemiological effects of MAP vaccines, and then estimate economically justifiable monetary values at which vaccines become economically beneficial to dairy producers such that a net present value (NPV) of a farm's net cash flow can be higher than the NPV of a farm using no control or alternative nonvaccine controls. Any vaccination with either low or high efficacy considered in this study yielded a higher NPV compared with a no MAP control. Moreover, high-efficacy vaccines generated an even higher NPV compared with alternative controls, making vaccination economically attractive. Two high-efficacy vaccines were particularly effective in MAP control and NPV maximization. One was a high-efficacy vaccine that reduced susceptibility to MAP infection. The other was a high-efficacy vaccine that had multiple efficacies on the dynamics of MAP infection and disease progress. Only one high-efficacy vaccine, in which the vaccine is targeted at reducing MAP shedding and the number of clinical cases, was not economically beneficial to dairy producers compared with an alternative nonvaccine control, when herds were highly infected with MAP.

Robust calculation of effective atomic numbers: the Auto-Z(eff) software

PURPOSE

The most appropriate method of evaluating the effective atomic number necessitates consideration of energy-dependent behavior. Previously, this required quite laborious calculation, which is why many scientists revert to over-simplistic power-law methods. The purpose of this work is to develop user-friendly software for the robust, energy-dependent computation of effective atomic numbers relevant within the context of medical physics, superseding the commonly employed simplistic power law approaches.

METHOD

Visual Basic was used to develop a GUI allowing the straightforward calculation of effective atomic numbers. Photon interaction cross section matrices are constructed for energies spanning 10 keV to 10 GeV and elements Z = 1-100. Coefficients for composite media are constructed via linear additivity of the fractional constituents and contrasted against the precalculated matrices at each energy, thereby associating an effective atomic number through interpolation of adjacent cross section data. Uncertainties are of the order of 1-2%.

RESULTS

Auto-Z(eff) allows rapid (∼0.6 s) calculation of effective atomic numbers for a range of predefined or user-specified media, allowing estimation of radiological properties and comparison of different media (for instance assessment of water equivalence). The accuracy of Auto-Z(eff) has been validated against numerous published theoretical and experimental predictions, demonstrating good agreement. The results also show that commonly employed power-law approaches are inaccurate, even in their intended regime of applicability (i.e., photoelectric regime). Furthermore, comparing the effective atomic numbers of composite materials using power-law approaches even in a relative fashion is shown to be inappropriate.

CONCLUSION

Auto-Z(eff) facilitates easy computation of effective atomic numbers as a function of energy, as well as average and spectral-weighted means. The results are significantly more accurate than normal power-law predictions. The software is freely available to interested readers, who are encouraged to contact the authors.

17 novel polymorphic microsatellite markers for the giant water bug, Abedus herberti (Belostomatidae)

The giant water bug (Abedus herberti) is a large flightless insect that is a keystone predator in aridland aquatic habitats. Extended droughts, possibly due to climate change and groundwater pumping, are causing once-perennial aquatic habitats to dry, resulting in serious conservation concern for some populations. A. herberti also exhibits exclusive male parental care, which has made it a model organism for studying mating systems evolution. Here we describe 17 novel polymorphic microsatellite loci developed for A. herberti. Number of alleles per locus ranged from 2 to 15, and average observed and expected heterozygosities were 0.579 and 0.697, respectively. These loci can successfully resolve both population genetic structure among sites separated by 3-100 km (F_ST = 0.08-0.21, P < 0.0001), and divergent mating strategies within local populations, making them highly useful for conservation genetics studies of this vulnerable species.

A systematic investigation of confirmed autoimmune loci in early-onset psoriasis reveals an association with IL2/IL21

BACKGROUND

Many autoimmune diseases share common susceptibility loci suggesting similar underlying cellular mechanisms involved in disease expression.

OBJECTIVES

The purpose of this investigation was to study 21 genetic variants in 14 genes that are confirmed autoimmune loci in a cohort of patients with early-onset psoriasis.

METHODS

Patients with early-onset psoriasis (n = 750) and controls (n = 3531) were genotyped using the Sequenom(®) MassArray™ iPLEX Gold platform.

RESULTS

We found strong evidence of association with two variants in the IL2/IL21 (rs6822844, genotypic P = 3·3 × 10(-4) ; rs2069778, genotypic P = 7·86 × 10(-4)) region.

CONCLUSIONS

The findings, although requiring replication, suggest that IL2/IL21 may play a key role in the pathogenesis of psoriasis as well as in other diverse autoimmune diseases.

Effects of intermittent hydrostatic pressure and BMP-2 on osteoarthritic human chondrocyte metabolism in vitro

PURPOSE

This study examined effects of intermittent hydrostatic pressure (IHP) and a chondrogenic growth factor, bone morphogenetic protein-2 (BMP-2), on anabolic, catabolic, and other metabolic markers in human osteoarthritic (OA) chondrocytes in vitro.

METHODS

Articular chondrocytes, isolated from femoral OA cartilage and maintained in high-density monolayer culture, were examined for effects of BMP-2 and IHP on gene expression of matrix-associated proteins (aggrecan, type II collagen, and SOX9) and catabolic matrix metalloproteinases (MMP-2 and MMP-3) and culture medium levels of the metabolic markers MMP-2, nitric oxide (NO), and glycosaminoglycan (GAG). The results were analyzed using a mixed linear regression model to investigate the effects of load and growth factor concentration.

RESULTS

IHP and BMP-2 modulated OA chondrocyte metabolism in accordance with growth factor concentration independently, without evidence of synergism or antagonism. Each type of stimulus acted independently on anabolic matrix gene expression. Type II collagen and SOX9 gene expression were stimulated by both IHP and BMP-2 whereas aggrecan was increased only by BMP-2. IHP exhibited a trend to decrease MMP-2 gene expression as a catabolic marker whereas BMP-2 did not. NO production was increased by addition of BMP-2 and IHP exhibited a trend for increased levels. GAG production was increased by BMP-2.

CONCLUSIONS

This study confirmed the hypothesis that human OA chondrocytes respond to a specific type of mechanical load, IHP, through enhanced articular cartilage macromolecule gene expression and that IHP, in combination with a chondrogenic growth factor BMP-2, additively enhanced matrix gene expression without interactive effects.

Differential recruitment of nuclear receptor coregulators in ligand-dependent transcriptional repression by estrogen receptor-α

Estrogen receptors (ERs) are normally expressed in breast tissues and mediate hormonal functions during development and in female reproductive physiology. In the majority of breast cancers, ERs are involved in regulating tumor cell proliferation and serve as prognostic markers and therapeutic targets in the management of hormone-dependent tumors. At the molecular level, ERs function as ligand-dependent transcription factors and activate target-gene expression following hormone stimulation. Recent transcriptomic and whole-genome-binding studies suggest, however, that ligand-activated ERs can also repress the expression of a significant subset of target genes. To characterize the molecular mechanisms of transcriptional repression by ERs, we examined recruitment of nuclear receptor coregulators, histone modifications and RNA polymerase II docking at ER-binding sites and cis-regulatory regions adjacent to repressed target genes. Moreover, we utilized gene expression data from patient samples to determine potential roles of repressed target genes in breast cancer biology. Results from these studies indicate that nuclear receptor corepressor recruitment is a key feature of ligand-dependent transcriptional repression by Ers, and some repressed target genes are associated with disease progression and response to endocrine therapy. These findings provide preliminary insights into a novel aspect of the molecular mechanisms of ER functions and their potential roles in hormonal carcinogenesis and breast cancer biology.

Effect of Johne's disease status on reproduction and culling in dairy cattle

Among the costs attributed to Mycobacterium avium ssp. paratuberculosis (MAP) infection in dairy cattle, the effects on reproduction and culling are the least documented. To estimate the cost of MAP infections and Johne's disease in a dairy herd, the rates of calving and culling were calculated for cows in each stage of MAP infection relative to uninfected cows. Data from 6 commercial dairy herds, consisting of 2,818 cows with 2,754 calvings and 1,483 cullings, were used for analysis. Every cow in each study herd was tested regularly for MAP, and herds were followed for between 4 and 7 yr. An ordinal categorical variable for Johne's disease status [test-negative, low-positive (low-shedding or ELISA-positive only), or high-shedding] was defined as a time-dependent variable for all cows with at least 1 positive test result or 2 negative test results. A Cox regression model, stratified on herd and controlling for the time-dependent infection variable, was used to analyze time to culling. Nonshedding animals were significantly less likely to be culled in comparison with animals in the low-shedding or ELISA-positive category, and high-shedding animals had nonsignificantly higher culling rates than low-shedding or ELISA-positive animals. Time to calving was analyzed using a proportional rates model, an analog to the Andersen-Gill regression model suitable for recurrent event data, stratifying on herd and weighted to adjust for the dependent censoring caused by the culling effects described above. High-shedding animals had lower calving rates in comparison with low-shedding or ELISA-positive animals, which tended to have higher calving rates than test-negative animals.

Nanopore formation by low-energy focused electron beam machining

The fabrication of nanopores in thin silicon nitride and aluminum oxide membranes by water vapor assisted, low-energy (0.2-20 kV) electron beam machining using a scanning electron microscope (SEM) is described. Using this technique, pores with diameters ranging in size from < 5 to 20 nm are easily formed. The nanopores are characterized by SEM, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The mechanism of etching is briefly discussed.

Repeated copulation and sperm precedence: paternity assurance for a male brooding water bug

Male giant water bugs (Abedus herberti Hidalgo) brood eggs attached to their backs by their mates. Brooders risk being "cuckolded" because females store sperm from previous matings. Males always copulate with females prior to receiving their eggs and mate repeatedly during oviposition. Experiments with a genetic marker reveal almost complete sperm precedence for the last male to mate with a female. The male's behavior therefore assures his paternity of the eggs he broods.

Peru coastal currents during el nino: 1976 and 1982

Year-long measurements of subsurface current and temperature on Peru's continental shelf included the onset of El Niño in 1976 and 1982. The Peru Coastal Undercurrent more than doubled in speed and advected anomalously warm water poleward. El Niño began in different seasons in 1976 and 1982, but the current and temperature responses were very similar. Acceleration of poleward flow at 10 degrees S occurred several days after sea level rose at the Galápagos Islands in October 1982, suggesting the onset of El Niño propagated as a Kelvin wave.

Biliary excretion of foreign compounds. Benzene and its derivatives in the rat

1. The extent of the excretion in the bile of the rat of benzene and 21 of its simple derivatives was studied. 2. Some 16 compounds of molecular weight less than 200, and including neutral molecules (benzene and toluene), aromatic acids, aromatic amines and phenols, were injected in solution intraperitoneally into biliary-cannulated rats. Metabolites in the bile were identified and estimated. The extent of biliary excretion of these compounds was low, i.e. 0-10% of the dose in 24hr., and most appeared in the bile mainly as conjugates. 3. The biliary excretion of six conjugates of molecular weight less than 300, including three glycine conjugates, one sulphate conjugate, one glucuronic acid conjugate and two acetyl derivatives, was low (less than 3% of the dose). 4. It is concluded that simple benzene derivatives of molecular weight less than about 300 are poorly excreted in rat bile.

Biliary excretion of foreign compounds. Biphenyl, stilboestrol and phenolphthalein in the rat: molecular weight, polarity and metabolism as factors in biliary excretion

1. The extent of biliary excretion of biphenyl, tetralin, stilboestrol and phenolphthalein was studied in the rat. 2. Biphenyl and its 4-hydroxy and 4,4'-dihydroxy derivatives are extensively excreted in the bile as glucuronides in amounts increasing in order of molecular weight. 3. Stilboestrol and its glucuronide are excreted almost quantitatively in the bile mainly as the monoglucuronide, as are also phenolphthalein and its glucuronide. 4. Tetralin is excreted to the extent of about 13% of the dose, mainly as ac-tetralyl glucuronides. 5. The results and those of Abou-El-Makarem, Millburn, Smith & Williams (1967) are discussed and it is concluded that the extent of biliary excretion of foreign compounds in rats depends on their molecular weight and their possessing a strongly polar anionic group. There appears to be a minimum value of this molecular weight below which little biliary excretion (i.e. not more than 5-10% of the dose) occurs. There is some latitude in the choice of this molecular weight, which is about 325+/-50. The necessary molecular weight and polar group can be acquired by metabolism. Above this minimum value biliary excretion increases with molecular weight. It is suggested that the mechanism of the biliary excretion of foreign compounds may be similar to that of conjugated bile acids, which are highly polar and whose molecular weights exceed 400.

Reduction of sulfur compounds in the sediments of a eutrophic lake basin

Concentrations of various sulfur compounds (SO(4), H(2)S, S, acid-volatile sulfide, and total sulfur) were determined in the profundal sediments and overlying water column of a shallow eutrophic lake. Low concentrations of sulfate relative to those of acid-volatile sulfide and total sulfur and a decrease in total sulfur with sediment depth implied that the contribution of dissimilatory sulfur reduction to H(2)S production was relatively minor. Addition of 1.0 mM Na(2)SO(4) to upper sediments in laboratory experiments resulted in the production of H(2)S with no apparent lag. Kinetic experiments with S demonstrated an apparent K(m) of 0.068 mmol of SO(4) reduced per liter of sediment per day, whereas tracer experiments with S indicated an average turnover time of the sediment sulfate pool of 1.5 h. Total sulfate reduction in a sediment depth profile to 15 cm was 15.3 mmol of sulfate reduced per m per day, which corresponds to a mineralization of 30% of the particulate organic matter entering the sediment. Reduction of S occurred at a slower rate. These results demonstrated that high rates of sulfate reduction occur in these sediments despite low concentrations of oxidized inorganic compounds and that this reduction can be important in the anaerobic mineralization of organic carbon.

Anaerobic oxalate degradation: widespread natural occurrence in aquatic sediments

Significant concentrations of oxalate (dissolved plus particulate) were present in sediments taken from a diversity of aquatic environments, ranging from 0.1 to 0.7 mmol/liter of sediment. These included pelagic and littoral sediments from two freshwater lakes (Searsville Lake, Calif., and Lake Tahoe, Calif.), a hypersaline, meromictic, alkaline lake (Big Soda Lake, Nev.), and a South San Francisco Bay mud flat and salt marsh. The oxalate concentration of several plant species which are potential detrital inputs to these aquatic sediments ranged from 0.1 to 5.0% (wt/wt). In experiments with litter bags, the oxalate content of Myriophyllum sp. samples buried in freshwater littoral sediments decreased to 7% of the original value in 175 days. This suggests that plant detritus is a potential source of the oxalate within these sediments. [C]oxalic acid was anaerobically degraded to CO(2) in all sediment types tested, with higher rates evident in littoral sediments than in the pelagic sediments of the lakes studied. The turnover time of the added [C]oxalate was less than 1 day in Searsville Lake littoral sediments. The total sediment oxalate concentration did not vary significantly between littoral and pelagic sediments and therefore did not appear to be controlling the rate of oxalate degradation. However, depth profiles of [C]oxalate mineralization and dissolved oxalate concentration were closely correlated in freshwater littoral sediments; both were greatest in the surface sediments (0 to 5 cm) and decreased with depth. The dissolved oxalate concentration (9.1 mumol/liter of sediment) was only 3% of the total extractable oxalate (277 mumol/liter of sediment) at the sediment surface. These results suggest that anaerobic oxalate degradation is a widespread phenomenon in aquatic sediments and may be limited by the dissolved oxalate concentration within these sediments.

Biliary excretion in foreign compounds. Sulphonamide drugs in the rat

1. The extent of biliary excretion in the rat of 15 sulphonamide compounds was studied. 2. Most of the sulphonamides studied, with molecular weights from 172 (sulphanilamide) to 352 (N(4)-acetylsulphadimethoxine) are poorly excreted in the bile (0-4% of the dose), except sulphapyridine, sulphamethoxypyridazine and sulphadimethoxine. The last three are partly metabolized to glucuronides, whose molecular weights and polarities are such as to allow them to be excreted in the bile in appreciable amounts. 3. Succinylsulphathiazole and phthalylsulphathiazole are polar and have molecular weights (355 and 403) of an appropriate order, and are excreted unchanged in the bile in appreciable amounts. 4. Sulphadimethoxine N(1)-glucuronide (mol.wt. 487) is extensively excreted in the bile unchanged. 5. The results are examined in the light of the hypotheses put forward in the preceding paper (Millburn, Smith & Williams, 1967).

Biliary excretion in foreign compounds. Species difference in biliary excretion

1. The biliary excretion of injected [(14)C]aniline, [(14)C]benzoic acid, 4-amino-hippuric acid and 4-acetamidohippuric acid in six or eight species of animal (rat, dog, hen, cat, rabbit, guinea pig, rhesus monkey and sheep) was studied. 2. These compounds, with molecular weights in the range 93-236, are poorly excreted in the bile in all the species examined and, in effect, there is little significant species difference in the extent of their biliary excretion. 3. Compounds of higher molecular weight (355-495) were also studied, namely succinylsulphathiazole, [(14)C]stilboestrol glucuronide, sulphadimethoxine N(1)-glucuronide and phenolphthalein glucuronide. 4. With these compounds a clear species difference in the extent of biliary excretion was found, the rat, dog and hen being good excretors, the rabbit, guinea pig and monkey poor excretors, and the cat and sheep taking an intermediary position. 5. There was a general trend for biliary excretion to be higher in all species when the compounds were of higher molecular weight. 6. These results are discussed in their relation to species differences in drug metabolism.

Autotrophic, hydrogen-oxidizing, denitrifying bacteria in groundwater, potential agents for bioremediation of nitrate contamination

Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent K(m) of 0.45 to 0.60 muM and a V(max) of 18.7 nmol cm h at 30 degrees C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strains grew autotrophically on hydrogen with either oxygen or nitrate as the electron acceptor. One strain grew mixotrophically. All of the isolates were capable of heterotrophic growth, but none were similar to Paracoccus denitrificans, a well-characterized hydrogen-oxidizing denitrifier. The kinetics for hydrogen uptake during denitrification were determined for each isolate with substrate depletion progress curves; the K(m)s ranged from 0.30 to 3.32 muM, with V(max)s of 1.85 to 13.29 fmol cell h. Because these organisms appear to be common constituents of the in situ population of the aquifer, produce innocuous end products, and could be manipulated to sequentially consume oxygen and then nitrate when both were present, these results suggest that these organisms may have significant potential for in situ bioremediation of nitrate contamination in groundwater.

Electron donors utilized by sulfate-reducing bacteria in eutrophic lake sediments

Mineralization rates of C-labeled substrates were determined in the presence and absence of Na(2)MoO(4), an inhibitor of sulfate reduction, in the profundal sediments of a shallow eutrophic lake. Sulfate reduction was inhibited by Na(2)MoO(4) at all concentrations tested (0.2 to 200 mM), whereas methane production was inhibited at Na(2)MoO(4) concentrations greater than 20 mM. Initial mineralization rates of glucose were unaffected by Na(2)MoO(4); however, Na(2)MoO(4) decreased the mineralization rates of lactate (58%), propionate (52%), an amino acid mixture (85%), and acetate (14%). These decreases in the rates of mineralization were attributed to inhibition of sulfate reduction. Hydrogen stimulated the reduction of SO(4) 2.5- to 2.8-fold, demonstrating potential hydrogen oxidation by sulfate-reducing bacteria. These results indicate that sulfate reducers utilize an array of substrates as electron donors and are of potential significance to the in situ mineralization of lactate, propionate, and free amino acids in these sediments.

Biliary excretion of [C]succinylsulphathiazole in the rat and rabbit

1. After intravenous injection about 30% of the dose (20mg./kg.) of succinylsulphathiazole is excreted unchanged in the bile in 3hr. by the rat, whereas only about 1% is excreted by the rabbit. When the renal pedicles are ligated the biliary excretion of succinylsulphathiazole in the rat increases to about 80% of the dose, but in the rabbit under these conditions the biliary excretion is only 2% of the dose. 2. In the rat, the sulphonamide readily enters the liver and biliary excretion occurs against a concentration gradient from liver to bile; further, the excretory process can be saturated, and can be depressed by the simultaneous administration of phenolphthalein glucuronide or bile salts. 3. In the rabbit, these conditions have not been found; succinylsulphathiazole does not readily enter the liver from the plasma, there is no transfer of the drug from the liver cells to the bile against a concentration gradient, and no saturation or depression of the biliary excretion of succinylsulphathiazole is found. 4. It is suggested that two factors responsible, at least partly, for the low biliary excretion of succinylsulphathiazole in the rabbit are the poor entry of the sulphonamide into the liver in this species and a deficiency of the concentrative mechanism for its excretion in the bile.

Electron beam stimulated oxidation of carbon

The patterning of carbon nanostructures by electron beam stimulated oxidation is described. Sputter deposited carbon thin films and carbon nanotubes are locally oxidized in a scanning electron microscope using injected water vapor. The resulting structures are examined with scanning electron microscopy and transmission electron microscopy. The electrical resistance obtained postprocessing is comparable to the as-deposited values. Linewidths are demonstrated down to 20 nm along with sub-2 nm nanowire fabrication in sputtered carbon films. A carbon nanowire is fabricated using this process and electrically characterized.