An Arabidopsis gene regulatory network for secondary cell wall synthesis.

The plant cell wall is an important factor for determining cell shape, function and response to the environment. Secondary cell walls, such as those found in xylem, are composed of cellulose, hemicelluloses and lignin and account for the bulk of plant biomass. The coordination between transcriptional regulation of synthesis for each polymer is complex and vital to cell function. A regulatory hierarchy of developmental switches has been proposed, although the full complement of regulators remains unknown. Here we present a protein-DNA network between Arabidopsis thaliana transcription factors and secondary cell wall metabolic genes with gene expression regulated by a series of feed-forward loops. This model allowed us to develop and validate new hypotheses about secondary wall gene regulation under abiotic stress. Distinct stresses are able to perturb targeted genes to potentially promote functional adaptation. These interactions will serve as a foundation for understanding the regulation of a complex, integral plant component.

Anisotropic optical and conductive properties of oriented 1D-nanoparticle thin films made by spray-assisted self-assembly.

We report on the fabrication of oriented anisotropic metal nanoparticle thin films made by Grazing Incidence Spraying (GIS) and on the anisotropic plasmonic properties of the resulting thin films. Gold nanorods of two different aspect ratios and silver nanowires were self-assembled as a uniaxially aligned monolayer with the GIS approach. In particular, we examine the influence of the nanowire/nanorod length and diameter on the degree of ordering determined by electron microscopy pictures. Furthermore, we show that the anisotropy of the optical properties (probed by polarized UV-visible-near infrared spectroscopy) strongly depend on the quality of alignment. The prepared monolayer thin films have an orientation order parameter of up to 0.83 for silver nanowires, which is reflected in an optical anisotropy of 0.57 in the UV-visible and 0.76 in the near infrared through the selective excitation of transverse and longitudinal surface plasmon resonance modes. The electronic transport in oriented silver nanowire monolayers is also shown to be highly directional, with the sheet resistance varying over almost an order of magnitude depending on the transport direction. Such anisotropic conductive plasmonic thin films may find applications in various fields like biochemical sensing, energy transport and harvesting or optoelectronic devices.

Comparison of environmental risk factors for esophageal atresia, anorectal malformations, and the combined phenotype in 263 German families.

Esophageal atresia with or without tracheoesophageal fistula (EA/TEF) and anorectal malformations (ARM) represent the severe ends of the fore- and hindgut malformation spectra. Previous research suggests that environmental factors are implicated in their etiology. These risk factors might indicate the influence of specific etiological mechanisms on distinct developmental processes (e.g. fore- vs. hindgut malformation). The present study compared environmental factors in patients with isolated EA/TEF, isolated ARM, and the combined phenotype during the periconceptional period and the first trimester of pregnancy in order to investigate the hypothesis that fore- and hindgut malformations involve differing environmental factors. Patients with isolated EA/TEF (n = 98), isolated ARM (n = 123), and the combined phenotype (n = 42) were included. Families were recruited within the context of two German multicenter studies of the genetic and environmental causes of EA/TEF (great consortium) and ARM (CURE-Net). Exposures of interest were ascertained using an epidemiological questionnaire. Chi-square, Fisher's exact, and Mann-Whitney U-tests were used to assess differences between the three phenotypes. Newborns with isolated EA/TEF and the combined phenotype had significantly lower birth weights than newborns with isolated ARM (P = 0.001 and P < 0.0001, respectively). Mothers of isolated EA/TEF consumed more alcohol periconceptional (80%) than mothers of isolated ARM or the combined phenotype (each 67%). Parental smoking (P = 0.003) and artificial reproductive techniques (P = 0.03) were associated with isolated ARM. Unexpectedly, maternal periconceptional multivitamin supplementation was most frequent among patients with the most severe form of disorder, i.e. the combined phenotype (19%). Significant differences in birth weight were apparent between the three phenotype groups. This might be attributable to the limited ability of EA/TEF fetuses to swallow amniotic fluid, thus depriving them of its nutritive properties. Furthermore, the present data suggest that fore- and hindgut malformations involve differing environmental factors. Maternal periconceptional multivitamin supplementation was highest among patients with the combined phenotype. This latter finding is contrary to expectation, and warrants further analysis in large prospective epidemiological studies.

A hydrodynamically optimized nano-electrospray ionization source and vacuum interface.

The coupling of atmospheric pressure ionization (API) sources like electrospray ionization (ESI) to vacuum based applications like mass spectrometry (MS) or ion beam deposition (IBD) is done by differential pumping, starting with a capillary or pinhole inlet. Because of its low ion transfer efficiency the inlet represents a major bottleneck for these applications. Here we present a nano-ESI vacuum interface optimized to exploit the hydrodynamic drag of the background gas for collimation and the reduction of space charge repulsion. Up to a space charge limit of 40 nA we observe 100% current transmission through a capillary with an inlet and show by MS and IBD experiments that the transmitted ion beams are well defined and free of additional contamination compared to a conventional interface. Based on computational fluid dynamics modelling and ion transport simulations, we show how the specific shape enhances the collimation of the ion cloud. Mass selected ion currents in the nanoampere range available further downstream in high vacuum open many perspectives for the efficient use of electrospray ion beam deposition (ES-IBD) as a surface coating method.

Nanotrench for nano and microparticle electrical interconnects.

We present a simple and versatile patterning procedure for the reliable and reproducible fabrication of high aspect ratio (10(4)) electrical interconnects that have separation distances down to 20 nm and lengths of several hundreds of microns. The process uses standard optical lithography techniques and allows parallel processing of many junctions, making it easily scalable and industrially relevant. We demonstrate the suitability of these nanotrenches as electrical interconnects for addressing micro and nanoparticles by realizing several circuits with integrated species. Furthermore, low impedance metal-metal low contacts are shown to be obtained when trapping a single metal-coated microsphere in the gap, emphasizing the intrinsic good electrical conductivity of the interconnects, even though a wet process is used. Highly resistive magnetite-based nanoparticles networks also demonstrate the advantage of the high aspect ratio of the nanotrenches for providing access to electrical properties of highly resistive materials, with leakage current levels below 1 pA.

Regulation of acetylation of plant cell wall components is complex and responds to external stimuli.

Previously, we reported that the allelic de-etiolated by zinc (dez) and trichome birefringence (tbr) mutants exhibit photomorphogenic development in the dark, which is enhanced by high Zn. TRICHOME BIREFRINGENCE-LIKE proteins had been implicated in transferring acetyl groups to various hemicelluloses. Pectin O-acetylation levels were lower in dark-grown dez seedlings than in the wild type. We observed Zn-enhanced photomorphogenesis in the dark also in the reduced wall acetylation 2 (rwa2-3) mutant, which exhibits lowered O-acetylation levels of cell wall macromolecules including pectins and xyloglucans, supporting a role for cell wall macromolecule O-acetylation in the photomorphogenic phenotypes of rwa2-3 and dez. Application of very short oligogalacturonides (vsOGs) restored skotomorphogenesis in dark-grown dez and rwa2-3. Here we demonstrate that in dez, O-acetylation of non-pectin cell wall components, notably of xyloglucan, is enhanced. Our results highlight the complexity of cell wall homeostasis and indicate against an influence of xyloglucan O-acetylation on light-dependent seedling development.

Substitution of L-fucose by L-galactose in cell walls of Arabidopsis mur1.

An Arabidopsis thaliana mutant (mur1) has less than 2 percent of the normal amounts of L-fucose in the primary cell walls of aerial portions of the plant. The survival of mur1 plants challenged the hypothesis that fucose is a required component of biologically active oligosaccharides derived from cell wall xyloglucan. However, the replacement of L-fucose (that is, 6-deoxy-L-galactose) by L-galactose does not detectably alter the biological activity of the oligosaccharides derived from xyloglucan. Thus, essential structural and conformational features of xyloglucan and xyloglucan-derived oligosaccharides are retained when L-galactose replaces L-fucose.

Spray-assisted alignment of Layer-by-Layer assembled silver nanowires: a general approach for the preparation of highly anisotropic nano-composite films.

The present article focuses on the build-up and the properties of oriented silver nanowire monolayer films and Layer-by-Layer assembled multilayer films. We describe the template-free oriented spray-assisted assembly of silver nanowires at solid/air-interfaces using Grazing Incidence Spraying, a simple and versatile approach that allows the formation of highly oriented thin films with a tunable density and in-plane orientation. Depending on the spraying conditions the nematic order parameter, which describes the angular spread of misaligned nanowires, can be as high as 0.98 (a value of 1.00 corresponding to a perfectly parallel alignment). The combination with the Layer-by-Layer assembly allows building multilayer thin films possessing in-plane anisotropy. In order to demonstrate that the local alignment does not cancel out on the macroscopic scale but leads to direction-dependent properties, we use linearly polarized UV-Vis-NIR spectroscopy to probe the selective excitation of the transverse and longitudinal localized plasmon resonances of the nanowires. The polarization efficiency of the thin films increases strongly with the in-plane density, the degree of orientation, and the number of silver nanowire layers. Multilayer films containing 4 layers of nanowires oriented in the same direction reach a polarization efficiency of up to 97% in the near-infrared region.

Protective effect of myostatin gene deletion on aging-related muscle metabolic decline.

While myostatin gene deletion is a promising therapy to fight muscle loss during aging, this approach induces also skeletal muscle metabolic changes such as mitochondrial deficits, redox alteration and increased fatigability. In the present study, we evaluated the effects of aging on these features in aged wild-type (WT) and mstn knockout (KO) mice. Moreover, to determine whether an enriched-antioxidant diet may be useful to prevent age-related disorders, we orally administered to the two genotypes a melon concentrate rich in superoxide dismutase for 12 weeks. We reported that mitochondrial functional abnormalities persisted (decreased state 3 and 4 of respiration; p<0.05) in skeletal muscle from aged KO mice; however, differences with WT mice were attenuated at old age in line with reduced difference on running endurance between the two genotypes. Interestingly, we showed an increase in glutathione levels, associated with lower lipid peroxidation levels in KO muscle. Enriched antioxidant diet reduced the aging-related negative effects on maximal aerobic velocity and running limit time (p<0.05) in both groups, with systemic adaptations on body weight. The redox status and the hypertrophic phenotype appeared to be beneficial to KO mice, mitigating the effect of aging on the skeletal muscle metabolic remodeling.

First-cycle blood counts and subsequent neutropenia, dose reduction, or delay in early-stage breast cancer therapy.

PURPOSE: If patients could be ranked according to their projected need for supportive care therapy, then more efficient and less costly treatment algorithms might be developed. This work reports on the construction of a model of neutropenia, dose reduction, or delay that rank-orders patients according to their need for costly supportive care such as granulocyte growth factors. PATIENTS AND METHODS: A case series and consecutive sample of patients treated for breast cancer were studied. Patients had received standard-dose adjuvant chemotherapy for early-stage nonmetastatic breast cancer and were treated by four medical oncologists. Using 95 patients and validated with 80 additional patients, development models were constructed to predict one or more of the following events: neutropenia (absolute neutrophil count [ANC] < or = 250/microL), dose reduction > or = 15% of that scheduled, or treatment delay > or = 7 days. Two approaches to modeling were attempted. The pretreatment approach used only pretreatment predictors such as chemotherapy regimen and radiation history; the conditional approach included, in addition, blood count information obtained in the first cycle of treatment. RESULTS: The pretreatment model was unsuccessful at predicting neutropenia, dose reduction, or delay (c-statistic = 0.63). Conditional models were good predictors of subsequent events after cycle 1 (c-statistic = 0.87 and 0.78 for development and validation samples, respectively). The depth of the first-cycle ANC was an excellent predictor of events in subsequent cycles (P = .0001 to .004). Chemotherapy plus radiation also increased the risk of subsequent events (P = .0011 to .0901). Decline in hemoglobin (HGB) level during the first cycle of therapy was a significant predictor of events in the development study (P = .0074 and .0015), and although the trend was similar in the validation study, HGB decline failed to reach statistical significance. CONCLUSION: It is possible to rank patients according to their need of supportive care based on blood counts observed in the first cycle of therapy. Such rankings may aid in the choice of appropriate supportive care for patients with early-stage breast cancer.

Modeling the cost-effectiveness of granulocyte colony-stimulating factor use in early-stage breast cancer.

PURPOSE: To model the cost-effectiveness (CE) of granulocyte colony-stimulating factor (G-CSF) in early-stage breast cancer when its use is directed to those most in need of the medication. METHODS: A conditional CE model was developed for the use of G-CSF based on a ranking of patient need as determined by patient blood counts during the first cycle of chemotherapy. In the base case, no G-CSF was used. In the alternative case, G-CSF was used in the following manner. If the risk of a neutropenic event (as defined by a predictive model based on nadir absolute neutrophil count [ANC] and hemoglobin decrease in cycle 1) was equal to or exceeded a predetermined critical value "T," then patients would receive G-CSF in cycles 2 through 6 of chemotherapy. If the risk of an event was less than T, patients would not use G-CSF unless an event occurred, at which time G-CSF would be administered with every subsequent cycle. RESULTS: A decision rule (T) that would allow the most needy 50% of early-stage breast cancer patients to receive G-CSF after the first cycle of chemotherapy resulted in a CE ratio of $34,297 dollars per life-year saved (LYS). If only the most needy 10% of patients received G-CSF, then the associated CE ratio was $23,748/LYS; if 90% of patients could receive the medication, the CE ratio would be $76,487/LYS. These estimates were relatively insensitive to inpatient hospital cost estimates (inpatient costs for fever and neutropenia of $3,090 to $7,726 per admission produced dollar per LYS figures of $34,297 to $32,415, respectively). However, the model was sensitive to assumptions about the shape of the relationship between dose reduction and disease-free survival (DFS) at 3 years. CONCLUSION: Providing G-CSF to the neediest 50% of early-stage breast cancer patients (as defined by first-cycle blood counts) starting after the first cycle of chemotherapy is associated with a CE ratio of $34,297/LYS, which is well in the range of CE ratios for treatment of other common medical conditions. Furthermore, conditional CE studies, based on predictive models that incorporate individual patient risk, allow one to define populations for which therapy is, or is not, cost-effective. Limitations of our present understanding of the shape of the chemotherapy dose-response curve, especially at low levels of dose reductions, affect these results. Further work is required to define the shape of the dose-response curve in early-stage breast cancer.

Access to kidney transplantation. Has the United States eliminated income and racial differences?

We analyzed the effect of patient and dialysis unit characteristics on access to kidney transplantation using several different approaches, including an analysis of individual patient data from a systematic random sample of 2900 new dialysis patients from each year 1981 to 1985 (14721 patients total). Additional analyses focused on the composition of transplant waiting lists and aggregate data from a 1984 census of 1133 dialysis and transplant units. White, male, young, nondiabetic, high-income patients treated in smaller units are more likely to receive a cadaver transplant under Medicare than are other kidney patients. Profit status of the dialysis unit was not found to be correlated to access to transplantation, although size of the unit may be correlated to access. Future analysis should focus on whether patient access has been inappropriately compromised. Possible factors unexplored in this analysis include differential patient preferences and medical suitability, as well as differential medical access.

Preservation of the delayed-type hypersensitivity response to alloantigen by xyloglucans or oligogalacturonide does not correlate with the capacity to reject ultraviolet-induced skin tumors in mice.

Chronic exposure to ultraviolet radiation suppresses T cell-mediated immune responses and induces the formation of suppressor T lymphocytes that prevent the rejection of highly antigenic ultraviolet-induced skin cancers in mice. Tamarind seed xyloglucans and pectinic oligogalacturonides prevent suppression of delayed-type hypersensitivity immune responses in mice to Candida albicans and alloantigen caused by a single exposure of ultraviolet radiation. We therefore investigated the ability of these poly/oligosaccharides to prevent suppression of T cell-mediated immune responses and suppressor cell induction during chronic ultraviolet irradiation and to preserve the capacity of ultraviolet-irradiated mice to reject a transplanted, highly antigenic, ultraviolet-induced tumor. C3H/HeN mice were treated 3x per week for 12 wk with 15 kJ per m2 ultraviolet B radiation followed by application of the polysaccharides/ oligosaccharides. The delayed-type hypersensitivity responses to C. albicans and alloantigen were measured after 1, 6, and 12 wk of treatment. Following the 12th wk of treatment the remaining mice were injected with the highly antigenic ultraviolet-induced, syngeneic tumor cell line UV5497-5. The polysaccharides/oligosaccharides protected delayed-type hypersensitivity responses to C. albicans but not contact hypersensitivity responses to dinitrofluorobenzene for up to 6 wk of ultraviolet radiation after which protection declined and suppressor cells were observed. In contrast, the delayed-type hypersensitivity response to alloantigen was preserved for the entire 12 wk of ultraviolet irradiation. Despite protection of immunity to alloantigen, the transplanted tumor cells grew equally well in all ultraviolet-irradiated animals. These results indicate that delayed-type hypersensitivity responses are heterogeneous and that delayed-type hypersensitivity to alloantigen is not a surrogate marker for rejection of ultraviolet-induced skin tumors.

The human mdr1 (multidrug-resistance) gene harbours a long homopyrimidine.homopurine sequence next to a cluster of Alu repeated sequences in intron 14.

In order to identify specific DNA sequences useful as 'genetic landmarks' in the construction of a complete map of the human mdr1 (multidrug-resistance) gene, we investigated the introns in the central region. In intron 14, we identified a long stretch of a homopyrimidine.homopurine sequence most probably adopting an unconventional DNA conformation, followed by a cluster of three Alu repeated sequences in an inverted orientation. Here, we describe the structure, formation and nucleotide sequence of these DNA elements.

Ki-ras oncogene and p53 tumour suppressor gene mutations in colorectal carcinomas from the European Saar-Luxembourg region are less frequent than predicted by the classic adenoma-carcinoma sequence model.

Recent investigations of colorectal cancer (CRC) have suggested that the accumulation of specific alterations in cell-growth regulating genes trigger the stage-wise progression to malignancy and that at least some of them could be useful for prognosis. In this study, the frequency, location and type of mutations of the Ki-ras proto-oncogene exons 1-2 and p53 tumour-suppressor gene exons 5-9 were analysed in colorectal carcinomas of 72 patients from the European Saar-Luxembourg region using PCR-SSCP screening and direct sequencing. The incidences of Ki-ras activating and p53 inactivating point mutations in these European samples were much lower (Ki-ras: 5 (6.9%) and p53: 13 (18.1%)) than reported for both genes in American studies (40-50% at least) (P < 1 x 10(-3)). These results suggest that other genetic mechanisms than those proposed for the classic adenoma-carcinoma sequence model can frequently underlie CRC development and that Ki-ras and p53 mutations should not be considered as universal markers for CRC.

The changing health care environment.

In 1985, the rate of growth of national health expenditures was more than twice the overall rate of growth in prices in the United States, while the percentage of health expenditures relative to the Gross National Product reached a record high of 10.7 percent. There have been almost no changes in the fraction of direct patient payments for medical care since 1980, or in the fraction paid by third parties or the government. Consequently, cost increases in the gross price of medical care are being transferred directly to the patient population. The expense associated with medical treatment and the availability of managed care systems (Health Maintenance Organizations and Preferred Provider Organizations, among others) have contributed to the increasing cost consciousness of patient and physician alike. One of the areas in which the spiralling costs of medical care are most deeply felt is in the treatment of hypertension. The direct costs for treating this condition, which affects more than 25 percent of the American population, exceed $8 billion annually. Furthermore, hypertension is a chronic condition in which the cost of treatment is continuously apparent to the patient. Moderate and severe hypertension is more likely to affect elderly and black patients, the people who are least able to pay for therapy. Difficulty in paying for therapy is becoming an increasingly important problem due to the trend among physicians to prescribe newer and more expensive antihypertensive drugs instead of the more commonly used diuretics and beta blockers. Due to the cost-conscious attitude of patients, the physician who chooses the more expensive drugs may run the risk of losing patronage among middle- and upper-income patients. In the case of lower-income patients, prescribing expensive drugs may result in noncompliance. In order to guard against incursions by managed care systems and ensure the best care for low-income patients, physicians must assume a cost-conscious attitude toward the treatment of hypertension.

Association of dialyzer reuse with hospitalization and survival rates among U.S. hemodialysis patients: do comorbidities matter?

The objective of this study was to determine whether the associations between reuse of hemodialyzers and higher rates of death and hospitalization persist after adjustment for comorbidity. This was a nonconcurrent cohort study of survival and hospitalization rates among 1491 U.S. chronic hemodialysis patients beginning treatment in 1986 and 1987. The impact of dialyzer reuse was compared across three survival models: an unadjusted model, a "base" model adjusted only for demographics and renal diagnosis, and an "augmented" model additionally adjusted for comorbidities. We found that reuse of dialyzers was associated with a similarly higher rate of death in analyses unadjusted for confounders (relative risk [RR] 1.25, 95% confidence interval [CI] 0.97-1.61), adjusted for demographics and renal diagnosis (RR 1.16, 95% CI 0.96-1.41), and analyses additionally adjusted for comorbidities (RR = 1.25, CI, 1.03, 1.52). Reusing dialyzers was also associated with a greater rate of hospitalization that was stable regardless of adjustment procedures. We conclude that higher rates of death and hospitalization associated with dialyzer reuse persist regardless of adjustment for demographic characteristics or baseline comorbidities. These findings amplify concerns that there exists elevated morbidity among hemodialysis patients treated in facilities that reuse hemodialyzers. Although the association we observed was not confounded by comorbidity, a cause-and-effect relationship between dialyzer reuse and morbidity could not be proved because of the inability to control for aspects of care other than dialyzer reuse.

The Clinton plan: what happened to the tough choices?

This paper points out four difficult choices embedded in the Clinton plan. First, universal coverage is achieved, but with regressive head-tax financing on many workers-since the cost of the employer mandate ultimately will fall on workers' wages. Perhaps such an approach can be made politically acceptable. Second, cost containment is entrusted to global spending limits, which will limit the rate of improvement in quality. Third, the offering of choice among a variety of health plans of different costs and quality, although desirable in itself, may lead to inequity. Finally, the plan's financing will make it difficult for voters to tell what trade-offs they are making, because employer mandates and budget cuts disguise choices.

Making a case for employer-enforced individual mandates.

An employer-enforced individual mandate has some substantial advantages over the mixed employer and individual mandate embodied in the Clinton administration's proposed health plan. Economic reasoning strongly suggests that almost all of the cost of an employer mandate will fall on workers and that in any case the incidence of an individual mandate is the same as that of an employer mandate. However, an individual mandate is easier for voters to understand, avoids administrative complexities and inequities, and eliminates the chance of adverse employment effects of mandated employer coverage.

When does curbing health costs really help the economy?

Growth in U.S. health spending has historically been associated with growth in prices paid to health care inputs in excess of economywide inflation and to increases in the employment of health inputs. Increases in input prices largely result in transfers from some citizens to others, while increases in employment mean less of other outputs--which is harmful if those other outputs are more valuable than medical services. Price increases are shown to account for 25 to 50 percent of U.S. medical spending growth in recent years.