bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive values for aspiration after endoscopic laser resections of malignant tumors of the hypopharynx and larynx
Authors: Bernal‐Sprekelsen Manuel , Vilaseca‐González Isabel , Blanch‐Alejandro Jose‐Luis
Published: January 2004

Background.

CO2‐laser surgery is a relatively new treatment for selected carcinomas of the upper aerodigestive tract. The purpose of our study was to evaluate prospectively the functional results for swallowing after C02‐laser resections.

Methods.

The sample was composed of 210 consecutive patients with malignancies of the larynx and hypopharynx treated with CO2 laser between February 1998 and January 2002. Endoscopic resections included all T1 and T2 tumors and selected T3 and T4 tumors. T1 glottic tumors were not included in the analysis. We assessed the need for a feeding tube and the period the tube remained in place, aspiration pneumonia, tracheotomy secondary to aspiration, the need for a permanent or temporary gastrostomy, and total laryngectomy secondary to aspiration.

Results.

The nasogastric feeding tube was used in 23.2% of small tumors (2.5 ± 8.04 days) and in 63% of locally advanced tumors (13.95 ± 22.55 days). Frequency and period of storage of the feeding tube were higher in locally advanced tumors (p = .0001). Twelve patients (5.7%) had postoperative pneumonia and 59 (28.1%) had temporary postoperative cough during oral intake. Aspiration symptoms correlated with location (p = .001) and locally advanced tumors (p = .016). Eight patients (3.8%) needed a postoperative tracheotomy for severe swallowing difficulties; six (2.9%) of them were definitive and two (0.95%) temporary. Thirteen gastrostomies (6.2%) were performed to avoid severe aspirations; five of them were definitive. The need for gastrostomy correlated significantly with location (p = .002), pT3 and pT4 tumors (p = .002), age (p = .02), and postoperative radiotherapy (p = .04). No correlation was found with the period of feeding tube (p = .38), or aspiration pneumonia (p = .24).

Conclusions.

Endoscopic resection of laryngeal and hypopharyngeal tumors is associated with good recovery of deglutition. Many tracheotomies are avoided, the need for a feeding tube is usually reduced, and organ preservation is often feasible even in locally advanced tumors. © 2003 Wiley Periodicals, Inc. Head Neck 26: 103–110, 2004
Single‐stage surgical repair of benign laryngotracheal stenosis in adults
Authors: van den Boogert Jolanda , Hans Hoeve L. J. , Struijs Ard , Hagenouw René R. P. M. , Bogers Ad J. J. C.
Published: January 2004

Background.

Benign laryngotracheal stenosis causes considerable morbidity. In a retrospective study, we describe the results of our surgical treatment.

Methods.

Between June 1999 and June 2002, 14 adults with laryngotracheal stenosis were referred to our hospital. Stenosis resulted from mechanical ventilation in 11 patients, from Wegener's granulomatosis in 2 patients, and from strangulation in 1 patient. Eleven patients had a tracheotomy. One patient was found unfit for surgery. Nine patients underwent cricotracheal resection (CTR) with end‐to‐end anastomosis, and four patients underwent single‐stage laryngotracheoplasty (SS‐LTP) without stenting.

Results.

There were no perioperative deaths. Patients were extubated after mean of 3 days (range, 0–10 days; CTR 2.3 days vs SS‐LTP 3.5 days, p = .45). There were in‐hospital complications in five patients. Mean hospital stay was 19 days (range, 8–53 days; after CTR 24 days vs SS‐LTP 9 days, p = .015). With regard to airway patency and voice recovery, 10 patients (77%) had good results, including 1 patient with two readmissions, and 3 (23%) had satisfactory results, including 1 patient with 11 additional nonsurgical interventions.

Conclusions

. Benign laryngotracheal stenosis in the adult patient can be repaired successfully using a strategy of two single‐stage surgical procedures. All patients had good or satisfactory functional results. A multidisciplinary approach was essential to achieve these good results. © 2004 Wiley Periodicals, Inc. Head Neck 26: 111–117, 2004
Technique of endoscopic retrograde puncture and dilatation of total esophageal stenosis in patients with radiation‐induced strictures
Authors: Lew Ronald J. , Shah Janak N. , Chalian Ara , Weber Randal S. , Williams Noel N. , Kochman Michael L.
Published: January 2004

Background.

Complete esophageal stenosis can occur after external beam radiation therapy for malignancies. Treatment for this complication has traditionally involved surgery.

Methods.

A new technique to reestablish luminal patency is described. This minimally invasive technique involves retrograde endoscopy by means of gastrostomy tube tract and puncture of the stenotic occlusion followed by stricture dilatation. The procedure is performed under combined endoscopic and laryngoscopic guidance.

Results.

Five consecutive patients who had complete esophageal stenoses develop after radiation therapy for malignant disease underwent retrograde endoscopy by way of gastrostomy tube tracts. Stenoses were punctured under endoscopic and laryngoscopic guidance with guide wires. Strictures were dilated with wire‐guided balloons or polyvinyl dilators. Luminal patency was established in all patients using this technique without procedural complications.

Conclusions.

Endoscopic retrograde puncture and dilatation of total esophageal stenoses is safe, effective, and useful to reestablish luminal patency for radiation‐induced strictures. This technique should be attempted before more invasive treatments. © 2004 Wiley Periodicals, Inc. Head Neck 26: 179–183, 2004
Radiotherapy alone or combined with surgery for adenoid cystic carcinoma of the head and neck
Authors: Mendenhall William M. , Morris Christopher G. , Amdur Robert J. , Werning John W. , Hinerman Russell W. , Villaret Douglas B.
Published: January 2004

Purpose.

The purpose of this study was to analyze the results of radiotherapy (RT) alone or combined with surgery for adenoid cystic carcinoma.

Methods.

Between September 1966 and November 2001, 101 previously untreated patients were treated with curative intent with RT alone or combined with surgery. Follow‐up ranged from 0.4–30.6 years (median, 6.6 years). All living patients had follow‐up for at least 1 year.

Results.

The 5‐ and 10‐year rates of local control were as follows: RT alone, 56% and 43%; surgery and RT, 94% and 91%; and overall, 77% and 69%. Multivariate analysis of local control revealed that T stage (p= .0101) and treatment group (p= .0008) significantly influenced this endpoint. The 5‐ and 10‐year rates of distant metastases‐free survival were 80% and 73%. The 5‐ and 10‐year absolute survival rates were as follows: RT alone, 57% and 42%; surgery and RT, 77% and 55%; and overall, 68% and 49%. Multivariate analysis of absolute survival revealed that T stage (p= .0043) and clinical nerve invasion (p= .0011) significantly influenced this endpoint. The 5‐ and 10‐year cause‐specific survival rates were as follows: RT alone, 65% and 48%; surgery and RT, 81% and 71%; and overall, 74% and 61%. Multivariate analysis revealed that T stage (p= .0008) and clinical nerve invasion (p= .0005) significantly influenced cause‐specific survival.

Conclusions.

The optimal treatment for patients with adenoid cystic carcinoma is surgery and adjuvant RT. A significant proportion of patients with incompletely resectable disease are cured after RT alone. Improvements in locoregional control are offset, in part, by the relatively high incidence of distant metastases. © 2004 Wiley Periodicals, Inc.Head Neck26:154–162, 2004
Seasonal transpiration pattern of Phragmites australis in a wetland of semi‐arid Spain
Authors: Moro María José , Domingo Francisco , López Germán
Published: January 2004

Transpiration rates were measured in a flooded population of Phragmites australis ssp. altissima in a wetland located in ‘El Hondo’ Natural Park (southeastern Spain) during the growing season of 2000. The heat balance method for measuring sap flow was used to calculate the rate of water transpiration on a whole‐stem basis. Four series of measurements were carried out in selected weeks in May, June, August and October. Structure, biomass and leaf area index of the reed population were simultaneously quantified in order to scale transpiration on a plot‐area basis.

Overall, transpiration flux was high during the sampling period and showed a typical diurnal pattern with a maximum at about midday. Mean transpiration was highest at the end of June coinciding with the peak of reed growth and with the maximum leaf area both at individual and plot scales. Rates decreased abruptly in October, in parallel with the advanced foliar senescence. The variation of both midday and integrated daily transpiration is significantly related to that of the air temperature on clear days. Cloudy and rainy days exert a pronounced effect on water loss by decreasing transpiration. Our results highlight the potential use of the sap‐flow method to measure transpiration in reed ecosystems and the relevance of this flux for the water balance in wetlands in semi‐arid environments. Thus, it is suggested that water management in these areas could be favoured by acquiring high‐quality experimental data. Copyright © 2004 John Wiley & Sons, Ltd.
Hydraulic conductivity of peat at Ellergower Moss, Scotland
Authors: Clymo R. S.
Published: January 2004

Falling head (and a few rising head) measurements were made of hydraulic conductivity k in a profile of a 7 m deep, small raised bog in southwest Scotland. The seven piezometer pipes were 39 mm diameter, and most of the measurements were made with attached tubes of 2·5 mm diameter, so that only 2–3 mm of water crossed the peat interface during a run. There were no consistent effects of pre‐flushing, direction of flow (falling, rising), or measuring‐tube size. Variability of 10–20% in k did not obscure an exponential decrease with depth from 5 × 10−6 cm s−1 at 100 cm to 0·7 × 10−6 cm s−1 at 500 cm. This decrease was uncorrelated with dry bulk density or peat stiffness, and only loosely so with a measure of humification. Calculated mean bulk velocity of pore water may be as low as 1 mm year−1. Pressure in the silty sand below the peat was 180 mbar less than expected, suggesting a thin highly impermeable layer (‘pan’?) at the peat base. The substratum may have hydrological connection with an adjacent lake. The hydraulic properties of this raised bog contrast strongly with those of a raised bog in Minnesota, and do not fit the assumptions made for Ingram's simple groundwater mound model of raised bog shape. Copyright © 2004 John Wiley & Sons, Ltd.
An assessment of the piezometer method for measuring the hydraulic conductivity of a Cladium mariscus—Phragmites australis root mat in a Norfolk (UK) fen
Authors: Baird Andrew J. , Surridge Ben W. J. , Money Russ P.
Published: January 2004

Despite their common global occurrence, little work has been done on characterizing the hydraulic properties of root mats, particularly their hydraulic conductivity K. A common method for estimating K in the field is the piezometer slug test. In some root mat systems, the piezometer slug test may be the only technique, field or laboratory, that is able to provide reliable estimates of K. We installed 17 piezometers in a Cladium mariscus L. (Pohl) and Phragmites australis Cav. (Streud.) root mat in a UK fen. Tests were initiated by both slug insertion and slug withdrawal. Repeat tests were conducted on some piezometers to check for test consistency. Rapid recoveries after both slug insertion and withdrawal were found, with 90% recovery reached for all tests within 1500 s and for many within 300 s. We found significant and highly reproducible differences between recovery after insertion and recovery after withdrawal, with the latter being more rapid than the former. We invoke a reversible pore blocking mechanism to explain this behaviour. Many of the piezometers showed recoveries after withdrawal that were broadly consistent with the assumption of a rigid porous medium in which Darcy's law holds. Tests on four further piezometers were used to examine the impact of piezometer ‘development’, different slug sizes and the use of ‘clean’ water on test behaviour. The results from these test piezometers were difficult to interpret. Nevertheless, it appears that replacing ‘dirty’ water in the piezometer standpipe with clean water leads to more rapid recoveries and reduces the difference between recovery after insertion and recovery after withdrawal. The K of the root mat, as estimated from withdrawal tests on 14 piezometers and standardized to 20°C, ranged between 0·00144 and 0·03022 cm s−1. This appears to be at the very top end of K values reported for fen peats and suggests that water can flow readily through this medium given sufficiently large hydraulic gradients. Copyright © 2004 John Wiley & Sons, Ltd.
Numerical modelling of groundwater flow and contaminant transport to Point Pelee marsh, Ontario, Canada
Authors: Crowe Allan S. , Shikaze Steven G. , Ptacek Carol J.
Published: January 2004

A numerical model was developed for simulating groundwater–wetland interactions and contaminant transport. The model calculates transient hydraulic head and a transient free surface in a two‐dimensional, heterogeneous domain, with variable and transient boundary conditions (infiltration, evapotranspiration, surface water), and water and contaminant fluxes across the aquifer–wetland interface. Contaminant transport is also simulated, with contaminant sources located at the free surface, wetland, or within the saturated domain. The model was applied to assess groundwater–wetland interactions and the transport of septic‐system‐derived contaminants at Point Pelee, Ontario, Canada. The model successfully simulated the field observations of groundwater flow and contaminant plumes. Where the barrier bar is narrow, the seasonal reversal in the direction of groundwater flow is caused by differences in the elevation of the water surface of Lake Erie and that of the marsh. This, in turn, induces the contaminants to oscillate between movement towards the lake during the winter and towards the marsh during the summer. Hence, contaminant plumes are bimodal in shape. Where the barrier bar becomes wider, the lake and the marsh have less effect, and hence contaminants move in one direction, along the principal direction of groundwater flow towards the marsh. Copyright © 2004 John Wiley & Sons, Ltd.
The influence of past and present hydrological conditions onSphagnumrecolonization and succession in a block‐cut bog, Québec
Authors: Price Jonathan S. , Whitehead Grant S.
Published: January 2004

This study of an abandoned cutover bog aims to understand the processes controlling moisture conditions that have led to distinct spatial patterns ofSphagnumrecolonization, and also how substrate conditions may have changed since abandonment and the implications for plant establishment. Two (unreplicated) symmetrical 12 × 3·5 m2quadrats either side of the centre‐line of a block‐cut trench were treated by removing all recolonized vegetation, includingSphagnum, from one quadrat (REMOV), examiningSphagnum‐covered (SPHAG) peat in the other, and bare peat (BARE) in both. Average volumetric soil moisture contents θ in the peat (2 cm below the surface) of the SPHAG and REMOV substrates were similar (∼86%), but greater than in BARE peat (∼78%). In a location not manipulated for this experiment, whereSphagnumcushions have re‐established on bare cutover peat, θ beneath the cushions was 5–14% greater than in bare cutover peat directly adjacent to it, indicating that cushions can regulate local substrate water storage, and benefit from it during periods of increased water demand. This may have assisted in the lateral expansion ofSphagnum. A loosely structured 0·5 to 1·0 cm thick organic litter layer (chiefly Ericaceae) overlying the BARE peat substrate slowed the rate of drying of bare peat in a laboratory sample. The laboratory tests found the capillary fringe to be up to 26 cm above the water table. The dry conditions and the larger pore structure of this litter layer hindered upward capillary flow and, therefore, plant water availability. In (occluded) ditches and low areas, the capillary fringe remained within 5 cm of the surface, and these locations supported the most completeSphagnumcover. In slightly higher areas, where the capillary fringe was about 20 cm below the surface, and because of the leaf litter, capillary water supply to the surface is sufficiently restricted to limitSphagnumrecolonization. These locations may have to await lateral expansion ofSphagnumcushions to achieve a full cover. Copyright © 2004 John Wiley & Sons, Ltd.
Soil aeration status in a lowland wet grassland
Authors: Barber K. R. , Leeds‐Harrison P. B. , Lawson C. S. , Gowing D. J. G.
Published: January 2004

The maintenance or development of plant community diversity in species‐rich wet grasslands has been a focus of water management considerations in the UK for the past 20 years. Much attention has been given to the control of water levels in the ditch systems within these wet grassland systems. In this paper we report measurements of aeration status and water‐table fluctuation made on a peat soil site at Tadham Moor in Somerset, UK, where water management has focused on the maintenance of wet conditions that often result in flooding in winter and wet soil conditions in the spring and summer. Measurement and modelling of the water‐table fluctuation indicates the possibility of variability in the aeration of the root environment and anoxic conditions for much of the winter period and for part of the spring and summer. We have used water content and redox potential measurements to characterize the aeration status of the peat soil. We find that air‐filled porosity is related to water‐table depth in these situations. Redox potentials in the spring were generally found to be low, implying a reducing condition for nitrate and iron. A significant relationship (p < 0·01) between redox potential and water‐table depth exists for data measured at 0·1 m depth, but no relationship could be found for data from 0·4 m depth. Copyright © 2004 John Wiley & Sons, Ltd.
Influence of hydrologic regime and vegetation on phosphorus retention in Everglades stormwater treatment area wetlands
Authors: White John R. , Ramesh Reddy K. , Moustafa M. Z.
Published: January 2004

The Florida (USA) Everglades ecosystem has been impacted due to increased loading of nutrients, in particular phosphorus (P), primarily from adjacent agricultural areas. Consequently, restoration measures involve the establishment of stormwater treatment areas (STAs) comprising a series of constructed wetlands. A series of mesocosms were established at the inflow of the Everglades Nutrient Removal Project wetland, the first such STA constructed. These mesocosms were designed to mimic STAs, as they operated as flow‐through systems and were packed with native soil. The objective of the study was to determine the effects of vegetation and hydrologic fluctuations on P retention/release by the wetland soil and on effluent water quality. Four treatment combinations consisted of continuously flooded with emergents (Typha), intermittently flooded with emergents, continuously flooded with no emergents, and intermittently flooded with no emergents. Intermittently flooded treatments underwent two 1 month drawdown events during the year. Soils were collected to determine the various pools of P and surface water samples were collected twice weekly to determine mass P flux in and out of the mesocosms. Results showed that the majority of the P was stored in the calcium‐ and magnesium‐bound fraction, as well as the refractory pool in the soil. Approximately 91% of the inflow soluble reactive P (SRP) mass was retained within the mesocosms for the continuously flooded treatment, and 80% was retained in the treatments subjected to periodic drawdown events, regardless of vegetation type. There was a net annual flux of dissolved organic P (DOP) out of the mesocosms for the drawdown treatments, whereas the net reduction in the DOP concentrations for the continuously flooded treatments was just 17%. These results demonstrate that, although these wetland systems perform well in reducing surface water SRP, additional research may need to focus on improving the reduction of DOP in order to reduce further the P loads to the nutrient‐sensitive Everglades system. Copyright © 2004 John Wiley & Sons, Ltd.
WETTRANS: a flow‐path‐oriented decision‐support system for the assessment of water and nitrogen exchange in riparian peatlands
Authors: Trepel Michael , Kluge Winfrid
Published: January 2004

Environmental authorities require quantitative predications of the nitrogen retention ability of riparian peatlands to aid in the selection of effective water management strategies for restoration. To support this decision‐making process, a matrix model connecting flow paths and nitrogen transformation was developed with a quasi‐stationary mass balance approach. The model concept is based on the assumptions that wetlands (1) receive water and nitrogen along several hydrological pathways, and (2) transformation of nitrogen occurs inside the wetland with different efficiencies, depending on the transition pattern between inflow and outflow pathways. These assumptions are formalized in a set of vectors describing the amount of water and the nitrogen concentration for each inflow pathway, a water distribution matrix between the inflowing water and several outflow pathways, a nitrogen transformation coefficient matrix of each inflow and outflow combination and, finally, two outflow vectors with the amount of water flowing out and the calculated nitrogen concentrations of each outflow pathway. The matrix model is applied to a drained valley peatland in order to quantify the effect of different water management options on an increase in nitrogen retention. Copyright © 2004 John Wiley & Sons, Ltd.
Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice
Authors: Tranter Martyn , Fountain Andrew G. , Fritsen Christian H. , Berry Lyons W. , Priscu John C. , Statham Peter J. , Welch Kathy A.
Published: January 2004

Cryoconite holes are near‐vertical tubes that form in the surface of glaciers when solar‐heated debris melts into the ice. Those that form in the McMurdo Dry Valleys of Antarctica are distinctive, in that they have ice lids and are closed to the atmosphere for periods of years to decades. Photoautotrophs and heterotrophs grow within this closed environment, perturbing the poorly buffered water chemistry, yet maintaining the potential for photosynthesis. Microbial excretion and decomposition of organic matter produces dissolved organic carbon (DOC): dissolved inorganic carbon ratios of ∼1:2. Much of the dissolved nitrogen pool (80–100%) exists as dissolved organic nitrogen (DON). The DON:DOC ratio is ∼1:11 (mol/mol), typical of organic particulate material at the Earth's surface. The combination of photoautotrophy, heterotrophy and weak chemical buffering within these microcosms promotes values of pH, pCO2, O2 saturation and percentage total dissolved nitrogen as DON that reach 10·99, 10−7·6 atm, 160% and 100% respectively, which are a unique combination among the surface waters on Earth. These ice‐sealed cryoconite holes could be important analogues of refugia on Snowball Earth and other icy planets. Copyright © 2004 John Wiley & Sons, Ltd.
Integrated strategies for maize irrigation and fertilization under water scarcity and environmental pressure in Bulgaria
Authors: Popova Zornitsa , Kercheva Milena
Published: January 2004

Integrated management of irrigation and fertilization could meet global increasing demand from maize production and environmental pressures under water scarcity. The objective of this paper was to evaluate the long‐term impact of irrigation scheduling and rates and timing of fertilization on water stress indicators, nitrogen uptake and leaching under maize on Chromic Luvisol (Sofia region). Modeling of the soil–plant system by the CERES‐maize model was used. Adjusted and modified CERES‐maize was run with different irrigation and fertilization scenarios and 30‐year weather data. Scenario analyses proved that grain yield and N‐uptake were severely affected on drylands under the conditions studied. Drought indicators showed that irrigation was required in 70% of the years. The sensitivity of maize drylands to precipitation in the critical (15 July–15 September) period caused great variability in maize yield (Cv=42%) and N‐uptake (Cv=25%) under nonlimited fertilization conditions. In addition, low vegetative precipitation proved to be a reason for fallow state leaching on drylands. All the irrigation scheduling tested improved N‐uptake efficiency, mitigated drought and significantly reduced yield and N‐uptake variability (Cv=5–6%). An integrated management strategy of N‐application timed to coincide with the period of maximum crop uptake and irrigation scheduled at 85% of field capacity reduced N available for leaching in the risky years. A drainage‐controlling scenario, developed for 75–80% of the required irrigation depth and satisfying predominantly the most sensitive phases of maize development, saved up to 95 mm yr−1 of water and reduced drainage in medium wet to wet fallow states by 30–40%. Significant early‐season N‐losses (25% of applied N) were associated with precipitation extremes and poor N‐dressing and could potentially happen in 3% of the years studied. Exceedance frequency of N‐uptake under nonlimited fertilization conditions and different irrigation strategies was used to adjust more accurately the fertilizer rates and timing for the soil and climate variability studied. Copyright © 2004 John Wiley & Sons, Ltd.
Advances in PLC‐based irrigation canal automation
Authors: Burt Charles M. , Piao Xianshu
Published: January 2004

A short history of canal automation is given. PLC‐based canal automation is relatively new. Advances in PLC‐based canal automation are listed. Also listed are some of the remaining challenges. Recent advances have been made in understanding unsteady flow simulation procedures, the form of the control algorithms used, the tuning procedures for these control algorithms, and the field programming of the algorithms into PLCs. The experiences of the Cal Poly Irrigation Training and Research Center (ITRC) in automating a variety of canals with upstream and downstream control are given. Copyright © 2004 John Wiley & Sons, Ltd.
Optimization of water management in the RUT Irrigation District, Colombia
Authors: Depeweg Herman , Fabiola Otero Martha
Published: January 2004

The RUT Irrigation District is a flat polder area with an infrastructure for irrigation, drainage and flood protection. Water is pumped out for drainage, mainly during the wet season and is pumped in for irrigation during the two growing seasons. The RUT Irrigation District is one of the 16 districts that were transferred by the Colombian government to a water users' association. During this process the farmers agreed to take over the management and to give up governmental subsidies. It appeared that the farmers grossly underestimated the future energy costs and nowadays they complain about high costs for operation and maintenance of the pumping stations. In addition, the service provided is not adequate and the condition of the pumps is declining.

The supplementary irrigation is based on the rainfall deficit, but a distinct criterion to supply water according to daily rainfall and cropping calendar does not exist. Hence, it is possible that more water than required is supplied to the area, affecting not only the pumping costs for irrigation but also for drainage. The present situation has been evaluated with a water balance at scheme level and an analysis of the measured groundwater fluctuations. Consecutively, a water balance at field level with an unsaturated groundwater flow model has been simulated to determine the irrigation requirements, yield reduction and drain flow based on a 20‐year analysis. The water balance at field level and the one‐, two‐ and three‐day rainfall with a return period of 5 years resulted in design drain flows. Finally, these flows were used in hydrodynamic simulations to analyse the pumping requirements for optimal drainage. The simulations also indicated the inundated areas to be expected for different rainfall intensities and frequencies. Copyright © 2004 John Wiley & Sons, Ltd.
On‐farm management of saline drainage water in arid and semi‐arid regions
Authors: Sharma D. P. , Tyagi N. K.
Published: January 2004

The irrigated arid and semi‐arid zones in India face twin problems of overall water scarcity and waterlogging accompanied by salinity. Subsurface drainage has proved successful in the rehabilitation and conservation of waterlogged saline soils. Drainage water from subsurface drainage systems seems to be an important source of water in the next millennium to tide us over the anticipated water scarcity problem in agriculture. However, the drainage waters from subsurface drainage systems are often saline and in the absence of a natural outlet, their disposal creates a problem. Various possible options have been discussed to mitigate the environmental threat posed by low quality drainage waters. Issues relating to potential reuse of low quality drainage waters along with management practices are addressed. Effects of factors influencing the long‐term sustainable use of saline drainage waters are presented and it is emphasized that special management practices have to be followed/evolved for site‐specific water quality, soil, crop and climatic conditions. However, the extent of salt leaching and crop establishment will depend on the total amount of monsoon rains and adequate subsurface drainage. It has been concluded that the use of a part of the saline drainage water in the post‐reclamation phase will not only augment the water supply but also minimize effluent disposal requirements. Copyright © 2004 John Wiley & Sons, Ltd.
Land preparation methods efficiency on the highland Vertisols of Ethiopia
Authors: Erkossa Teklu , Gizaw Assefa , Stahr Karl
Published: January 2004

Vertisols are among the major high potential soils in the central highlands of Ethiopia. Their productivity is constrained by severe waterlogging. Under traditional management systems, yield from these soils is far below the potential. To bridge the gap, several surface drainage methods were introduced and have shown a yield advantage over some of the traditional methods. However, alternative technologies for better crop yield and improved land resources management are still needed for sustainable use of the soils and water resources. As part of a concerted effort to improve productivity, field experiments were conducted during the 1996 and 1997 at Gincii, and 1998–2000 growing seasons at Caffee Doonsaa. Three land preparation methods, broad bed and furrows (BBF), ridge and furrows (RF) and flat seedbeds (FL) for the former, and four alternatives, BBF, RF, reduced tillage (RT) and green manuring (GM) for the latter, were evaluated. A randomized complete block design (RCBD) was used with three replications on permanent plots. Surface runoff and crops yields were considered as indicators of the efficiency of the land preparation methods. BBF gave the highest runoff at both locations over the years, but the effects on crop yields were inconsistent at both locations. BBF gave the lowest and the highest grain and straw yields in the first and the second years, respectively, at Gincii. GM and RT for cereals and BBF for a legume have shown better yield advantage at Caffee Doonsaa. To arrive at reliable conclusions, it is recommended that the experiment be continued under the prevailing cropping systems, taking soil quality and other sustainability indicators into account. Copyright © 2004 John Wiley & Sons, Ltd.
Responsive and recognitive hydrogels using star polymers
Authors: Oral Ebru , Peppas Nicholas A.
Published: January 2004

Polymeric networks that have inherent capabilities to recognize different molecules and chemical changes in their environment are the next generation of materials that will aid in the diagnosis and treatment of diseases. We have prepared new networks based on star polymers that were designed to be responsive and recognitive. Using molecular imprinting with D‐glucose and crosslinking with poly(ethylene glycol) dimethacrylate with an ethylene glycol chain of nominal molecular weight 600, we prepared star polymer networks, which exhibited over 300% more uptake for D‐glucose compared to D‐fructose. Using copolymerization with methacrylic acid, we prepared star polymer networks with pH‐sensitivity, which showed a sharp transition in swelling around a pH of 4.5. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 439–447, 2004
Anti‐inflammatory effects of a titanium‐peroxy gel: Role of oxygen metabolites and apoptosis
Authors: Larsson Jenny , Persson Carina , Tengvall Pentti , Lundqvist‐Gustafsson Helen
Published: January 2004

Polymorphonuclear neutrophils (PMN) are among the first inflammatory cells to arrive at an implant interface, where they encounter with the foreign material and may produce reactive oxygen species (ROS). During the interaction between titanium and ROS, titanium‐peroxy (Ti‐peroxy) compounds may be formed. We used a Ti‐peroxy gel, made from titanium and hydrogen peroxide, to study the effects of Ti‐peroxy compounds on PMN. In the absence of serum, the Ti‐peroxy gel decreased the oxidative response of PMN to yeast and PMA and reduced PMN apoptosis without inducing necrosis. These effects could not be ascribed to the release of hydrogen peroxide from the Ti‐peroxy gel, because a steady‐state hydrogen peroxide producing system failed to mimic the effects of the gel. The effects were similarly unaffected when PMN were preincubated with β2‐integrin antibodies, questioning the involvement of adhesion molecules. Nevertheless, when a filter was used to separate the Ti‐peroxy gel from the cells, the gel effect on PMN life span was abolished, pointing to a contact‐dependent mechanism. In the presence of serum, the Ti‐peroxy gel had no effect on the PMN oxidative response and life span, but appeared rather inert. In summary, this study demonstrates that the Ti‐peroxy gel has potentially anti‐inflammatory properties through a combined peroxide and physical contact effect, supporting the notion that interactions between titanium and inflammatory cells are responsible for the good performance of titanium in vivo. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 448–457, 2004
Polymeric sustained local drug delivery system for the prevention of vascular intimal hyperplasia
Authors: Kanjickal Deenu , Lopina Stephanie , Evancho‐Chapman M. Michelle , Schmidt Steven , Donovan Duane , Springhetti Sara
Published: January 2004

Anastomotic intimal hyperplasia (IH) is a major cause of both autologous vein and synthetic vascular graft failure. We have previously published data suggesting that cyclosporin may reduce the development of IH in a canine model. However, systemic administration of cyclosporin could create serious adverse effects. Therefore, it is our long‐term goal to test the hypothesis that the controlled local release of cyclosporin from a polymeric vascular wrap will prevent the development of IH. To test this hypothesis, we developed a controlled release vascular wrap (sheet/ring) using a poly(ethylene glycol) (PEG) hydrogel. Sterilization of the polymers was performed using the ethylene oxide and hydrogen peroxide sterilization methods. It was found that except for one combination (8000 molecular weight and 1:1 crosslinking ratio), the differences in the swelling ratios for the sterilized and unsterilized hydrogels were not statistically significant. Release studies from unsterilized and ethylene oxide‐sterilized PEG hydrogels were conducted. It was found that release lasted for approximately 50 h for sterilized as well as unsterilized PEG hydrogels. Acute animal studies, to test the deployment of both the polymeric sheets and rings to the adventitial surface of native arteries and veins, were completed successfully. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 489–495, 2004
Macroporous poly(ϵ‐caprolactone) with antimicrobial activity obtained by iodine polymerization
Authors: de Arruda Almeida Kleber , de Queiroz Alvaro Antonio Alencar , Higa Olga Zazuco , Abraham Gustavo Abel , San Román Julio
Published: January 2004

The most serious problem usually encountered in the field of implanted biomedical devices is infectious morbidity as a primary source of mortality. In this work, the synthesis and characterization of a macroporous iodine‐based sanitizer (iodophor), poly(caprolactone)‐iodine (PCL‐I2), are presented. Characterization methods include nuclear magnetic resonance spectroscopy, gel permeation chromatography, nitrogen adsorption‐desorption, and scanning electron microscopy. The in vitro cytotoxicity to CHO cells based on cell viability with Chinese hamster ovary cells (CHO) and antimicrobial activities against Escherichia coli and Staphylococcus aureus were examined. The obtained macropore PCL‐I2 structures had a rather narrow size distribution. The PCL‐I2 iodophor was noncytotoxic to Chinese hamster ovary cells. The antimicrobial activities of the PCL‐I2 were assessed against E. coli and S. aureus. The tested PCL‐I2 showed better antimicrobial activity against E. coli than against S. aureus. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 473–478, 2004
Small changes in the polymer structure influence the adsorption behavior of fibrinogen on polymer surfaces: Validation of a new rapid screening technique
Authors: Weber Norbert , Bolikal Durgadas , Bourke Sharon L. , Kohn Joachim
Published: January 2004

Numerous studies conclude that the selective adsorption of plasma proteins on materials contacting blood or tissue affects all subsequent interactions related to the biocompatibility of artificial surfaces. However, there are only a few studies available, which clearly demonstrate that there is a correlation between surface chemistry and selective protein adsorption. Detailed knowledge of such correlations would facilitate the design of biocompatible materials. In this study, a rapid, fluorescence‐based, screening technique using a 384‐well format for polymer–protein interactions was developed. The screening assay was used to measure the adsorption of human fibrinogen on 46 test polymers (44 polyarylates selected from a combinatorial library of tyrosine‐derived polyarylates, and two lactide‐based polymers). In this library of polyarylates, structural changes are generated by variations in either the polymer backbone or the polymer pendent chain. Although no overall trend between polymer hydrophobicity and fibrinogen adsorption could be identified using the entire set of test polymers (R2 = 0.43), fibrinogen adsorption was clearly correlated with variations in the pendent chain structure. Thus, when the test polymers were grouped by backbone composition, increased hydrophobicity of the pendent chain was significantly correlated with reduced fibrinogen adsorption. The following R2 coefficients within the polymer backbone groups were determined: 0.87 (diglycolates); 0.98 (glutarates); 0.73 (adipates); 0.87 (suberates); 0.67 (3‐methyl‐adipates). Our results demonstrate that it is possible to screen for protein–material interactions in a cost‐effective fashion using a miniaturized immunofluorescence technique. Further, we demonstrate that small changes in chemical composition can significantly influence the adsorption of human fibrinogen on polymer surfaces. The lactide‐based polymers were among those polymers exhibiting the highest tendency to adsorb fibrinogen. This information may be useful when polymers have to be selected for specific biomaterial applications. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 496–503, 2004
In vivo cancellous bone remodeling on a strontium‐containing hydroxyapatite (sr‐HA) bioactive cement
Authors: Wong C. T. , Lu W. W. , Chan W. K. , Cheung K. M. C. , Luk K. D. K. , Lu D. S. , Rabie A. B. M. , Deng L. F. , Leong J. C. Y.
Published: January 2004

The purpose of this study was to investigate the in vivo bone response to the strontium‐containing hydroxyapatite (Sr‐HA) bioactive bone cement injected into the cancellous bone. Sr‐HA cement was injected into the iliac crest of rabbits for 1, 3, and 6 months. Active bone formation and remodeling were observed after 1 month. Newly formed bone was observed to grow onto the bone cement after 3 months. Thick osteoid layer with osteoblasts formed along the bone and guided over the bone cement surface reflected the stimulating effect of Sr‐HA. From scanning electron microscopy (SEM) and energy‐dispersive X‐ray (EDX) analysis, high calcium and phosphorus levels were detected at the interface with a thick layer of 70 μm in width, and fusion of Sr‐HA with the bone was observed. Blood vessels were found developing in remodeling sites. The affinity of bone on Sr‐HA cement was increased from 73.55 ± 3.50% after 3 months up to 85.15 ± 2.74% after 6 months (p < 0.01). In contrast to Sr‐HA cement, poly(methyl methacrylate) (PMMA) bone cement was neither osteoconductive nor bioresorbable. Results show that the Sr‐HA cement is biocompatible and osteoconductive, which is suitable for use in treating osteoporotic vertebral fractures. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 513–521, 2004
Dissolution control and cellular responses of calcium phosphate coatings on zirconia porous scaffold
Authors: Kim Hae‐Won , Kim Hyoun‐Ee , Salih Vehid , Knowles Jonathan C.
Published: January 2004

Different types of calcium phosphates [hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), and their composites (HA + FA, HA + TCP)] were coated on a zirconia (ZrO2) porous scaffold using a powder slurry method. The ZrO2 porous scaffold was intended for a load‐bearing implant, and the apatite layers were coated to improve osteoconductivity. The insertion of an FA intermediate layer between the coating layer and ZrO2 scaffold effectively suppressed the reaction between the calcium phosphate and ZrO2 and maintained the coating layer at the initial powder composition. The obtained coating layer, of a thickness of ∼30 μm, was relatively microporous and firmly adherent to the ZrO2 scaffold. Dissolution tests in physiological solution showed typical differences depending on the coating layers, with the dissolution rate increasing in the order TCP > HA + TCP > HA > HA + FA > FA. This result suggests the functional coating of the calcium phosphates in view of tailoring the solubility. Osteoblast‐like cells, MG63 and HOS, responded similarly in terms of cell growth, morphology, and proliferation rate regardless of the coating types, indicating favorable and comparable cell viability. However, the alkaline phosphatase (ALP) activity of the cells on the pure HA and HA composite coatings (HA + FA and HA + TCP) expressed at higher levels compared to those on pure FA and pure TCP coatings for both MG63 and HOS cells, suggesting a selective cell activity depending on the coating types. All the calcium phosphate‐coated‐ZrO2 scaffolds showed higher ALP levels compared to pure ZrO2 scaffold. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 522–530, 2004
AFM observation of collapse and expansion of phosphoric acid‐demineralized dentin
Authors: Nakabayashi Nobuo , Watanabe Akihiko , Igarashi Kayo
Published: January 2004

The objective of this study is to provide additional data regarding morphological changes that occur to dentin matrices following demineralization with etchants. Our understanding of the mechanism of diffusion of comonomers into the demineralized substrate is very limited. It has been hypothesized that certain water‐soluble polyelectrolytes (acidic proteins) and neutral proteins in dentin can influence the collapse of demineralized dentin when it is air dried. Some of these solubilized substances are thought to aggregate by the action of Ca cations, which become dissolved during H3PO4 etching, ultimately resulting in some degree of collapse. In the current study, dentin surfaces were examined by atomic force microscopy (AFM) before and after treatment by 10% H3PO4containing increasing concentrations of CaHPO4. Reversal of matrix collapse by aqueous 30% 2‐hydroxyethyl methacrylate (HEMA) was evaluated by AMF for 60 min. The results demonstrate two forms of matrix collapse; we speculate that one form is induced by acidic noncollagenous polyelectrolytes and the other by neutral peptides. Our data indicate that further evaluation of the influence of endogenous noncollagenous proteins must be studied to understand the mechanism of the collapse and reexpansion dynamics of demineralized dentin networks. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 558–565, 2004
Scaled interfacial activity of proteins at the liquid–vapor interface
Authors: Krishnan Anandi , Sturgeon Jacqueline , Siedlecki Christopher A. , Vogler Erwin A.
Published: January 2004

A principal conclusion drawn from observations of time‐ and concentration‐dependent liquid–vapor (LV) interfacial tension γlv of a diverse selection of proteins ranging from albumin to ubiquitin spanning nearly three decades in molecular weight (MW) is that concentration scaling substantially alters perception of protein interfacial activity as measured by reduction in γlv. Proteins appear more similar than dissimilar on a weight/volume basis, whereas molarity scaling reveals a “Traube‐rule” ordering by MW, suggesting that adsorption is substantially driven by solution concentration rather than diversity in protein amphilicity. Scaling as a ratio‐to‐physiological‐concentration demonstrates that certain proteins exhibit the full possible range of interfacial activity at and well‐below physiological concentration, whereas others are only weakly surface active within this range, requiring substantially higher solution concentration to achieve reduction in γlv. Important among this latter category of proteins are the blood factors XII and XIIa, assumed by the classical biochemical mechanism of plasma coagulation to adsorb to procoagulant surfaces, even in the presence of overwhelming concentrations of other blood constituents such as albumin and immunoglobulin that are shown by this work to be among the class of highly surface‐active proteins at physiologic concentration. A comparison of pendant drop and Wilhelmy balance tensiometry as tools for assessing protein interfacial activity shows that measurement conditions employed in the typical Wilhelmy plate approach fails to achieve the steady‐state adsorption condition that is accessible to pendant drop tensiometry. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 544–557, 2004