Conventional Filter Paper Research Articles

Enhancing the electromagnetic interference shielding performance of composite paper with corrugated paper-like structure

The structural design of material significantly influences its electromagnetic interference (EMI) shielding performance, providing an intelligent approach to attain desirable EMI shielding performances. Inspired by the ultra-large distance of the middle layer in corrugated paper, we proposed a novel composite paper with corrugated paper-like structure via the assembling of two pieces of surface-modified filter paper and an aerogel film. Specifically, a conventional filter paper was modified with the conductive hydrogel film consisting of TEMPO-oxidized cellulose nanofibers (TOCNF), cationic starch (CS) and Ti3C2Tx. The TOCNF and CS rapidly formed a composite hydrogel when mixed, due to their electrostatic interactions. The aforementioned aerogel film was produced through the freeze-drying of TOCNF/CS hydrogel, and it enlarged the distance between two conductive hydrogel film modified papers when inserted. The assembled composite papers demonstrated a maximum EMI SE of 71.0 dB, improved by 19.7 % as compared to the control without the aerogel film (59.3 dB). The expansion of the distance between conductive layers likely facilitated the enhancement in the multiple reflections and absorptions of electromagnetic waves. This novel composite paper showed better EMI shielding performance than many previously-reported materials considering the thickness and conductive filler dosage. In addition, the composite paper also showed exceptional infrared stealth capabilities since it effectively shielded the thermal radiation from human body. The composite paper still exhibited good infrared stealth ability at high temperature conditions (up to 120 ℃). Therefore, this research could inspire innovative concepts in designing high-performance and multifunctional EMI shielding materials in an economical way.

A double-sided coating paper antibacterial indicator card based on polyvinyl alcohol/sodium carboxymethyl cellulose-anthocyanins and chitosan-halloysite nanotubes loaded essential oil to monitor fish freshness

This study developed a multifunctional paper-based freshness antibacterial indicator card by dual-sided coating on conventional filter paper. The indicator coating was composed of anthocyanins from purple cabbage, and polyvinyl alcohol and sodium carboxymethyl cellulose as substrates while the antibacterial coating contained halloysite nanotubes for loaded thyme essential oil and chitosan. FT-IR, XRD, and SEM analyses revealed that the components were well-mixed, and the paper was tightly bound to the coatings through hydrogen bonds. Additionally, the coating effectively filled the porous fiber gaps in the paper, significantly enhancing the mechanical properties of the paper. The tensile strength of the coated paper was enhanced from 14.28 MPa to a range of 42.25–47.71 MPa, and the bending resistance was increased from 0.35 N·mm to a range of 1.72–1.99 N·mm compared to the uncoated paper. The addition of anthocyanins provided excellent sensitivity to pH and ammonia for the indicator card. Furthermore, the coating including halloysite nanotubes for loaded thyme essential oil exhibited antimicrobial resistance against Escherichia coli and Staphylococcus aureus. When used on fresh carp, the antibacterial indicator card not only indicated the freshness of the carp but also extended the best before date of the fish meat by 1–2 days. The indicator exhibited the most pronounced color transformation and optimal freshness indication performance when the mass fraction of anthocyanins was 2 %.

Portable intelligent paper-based sensors for rapid colorimetric and smartphone-assisted analysis of hydrogen peroxide for food, environmental and medical detection applications

One of the effective approaches to safeguard human health is the rapid and sensitive identification of food additives, environmental pollutants, and disease markers. This study developed a portable intelligent paper-based sensor for point-of-care detection of hydrogen peroxide (H2O2) and sarcosine (SA) using smartphone colorimetric analysis, supplemented by UV-Vis verification. The paper-based sensor utilizes a chemical modification of conventional filter paper by immobilizing horseradish peroxidase (HRP) from the horseradish plant, achieved through boronate affinity and metal chelation techniques. For H2O2 detection, the sensor exhibited a linear range of 2–100 µmol L−1 and a limit of detection (LOD) of 1.0 µmol L−1. Similarly, a range of 2–400 μmol L−1 for SA detection and an LOD of 1.0 μmol L−1. The sensors were successfully employed for determining the H2O2 concentration in liquor samples, environmental water, and the amount of SA in urine. Significantly, the detection ranges of these sensors surpassed those of commercially available test strips. In summary, we first proposed enzyme-immobilized paper-based sensors for immobilizing HRP from plants to detect H2O2 and SA, which are intelligent, portable, fast, green, low-cost, highly sensitive, and selective, with broad application prospects in food analysis, environmental monitoring, and medical diagnostics.

Chitosan modified filter paper separators with specific ion adsorption to inhibit side reactions and induce uniform Zn deposition for aqueous Zn batteries

The electrochemical performance of Zn metal anode in aqueous batteries is serious challenged by side reactions and dendrite growth. Separators are important cell components, which directly interact with electrolyte species and present potential solutions to regulate Zn anode performance. Herein, we modify the conventional filter paper separators by coating chitosan on the fibers. The hydroxyl, amino and ether groups on chitosan allow preferential adsorptions of proton, zinc ion and sulfate in ZnSO4 aqueous electrolytes. Proton adsorption suppresses the proton activity, which inhibits corrosions and hydrogen evolution reactions at Zn electrode. The interactions of zinc ion and sulfate with chitosan regulate the ion transport manner and enlarge Zn2+ transference number, which ensures homogeneous Zn nucleation and growth. With the application of chitosan modified filter paper separators, the Zn electrode presents a long cycle life of 2900 h. A high coulombic efficiency of 99.6% is achieved. The chitosan modified separators also enhance the capacity retention of Zn||MnO2 batteries from 52.8% to 98.4% over 1000 cycles. Our work presents an effective separator regulation approach for high-performance aqueous Zn batteries.

Performance Tests of a Washable Incontinence Pants - Urine Absorbency Test

요실금은 노인들의 주요 건강 문제 중 하나이며, 노인 여성의 유병율은 64.2 %로 보고되고 있다. 요실금 관리를 위한 소변 흡수 제품에는 여러 유형이 있는데 요실금 팬티는 정상적 인 속옷처럼 보이도록 설계되어있어 가벼운 요실금 환자에게 좋은 요실금제품이다. 폭 넓은 이용 가능성에도 불구하고 세탁 가능한 요실금 팬티에 대한 성능 테스트의 국제 표준은 아직 없으며, 본 연구는 세탁하여 재사용이 가능한 요실금 팬티의 성능 시험 방법을 개발하기 위한 목적이다. 우리는 ISO 11948-1: Urine absorbing aids. Part 1: Whole product testing and a standard를 이용한 최대흡수량을 측정하고, 한국고령친화용품 산업협회의 단체표준인 SPS-KSPA-1014-7240: Urinary incontinence panty를 적용하여 요실금 팬티의 역류량 측정법을 이용한 최대흡수량, 그리고 소변 누출로 측정되는 최대흡수량을 계산하였다. 역류량 측정법을 이용한 최대흡수량은 146.67(±10.95)ml, 누출 관찰을 기준으로 측정한 최대흡수량은 246.67(±41.47)ml, ISO 11948-1을 기준으로 측정한 최대흡수량은 325.48(±9.44)g이었다. ISO 11948-1의 방법은 가장 작은 변동 계수를 가져 측정의 정확성이 보장되지만, 제품 사용의 실제 환경과는 거리가 크다. 재흡수 질량 및 누출 관찰을 이용한 소변 흡수량 측정은 10-30%의 더 큰 변동 계수를 가지지만 실제 사용 환경과 유사하므로 임상적 의의가 있는 것으로 사료된다. 본 연구에서는 기존의 여과지 대신에 갈색의 흡수지를 사용하였는데 소변의 역류 및 누출을 감지하는데 훨씬 효과적이었다. 따라서 성인용 기저귀나 요실금 팬티의 성능시험에서 기존의 여과지 대신 흡수지를 사용할 것을 제안한다.Urinary incontinence is one of the major health issues among the elderly, and the prevalence incontinence in elderly women is reported to be as high as 64.2 %. There are many types of urine absorbing products for managing urinary incontinence. Washable incontinence pants are designed to look like regular underwear, and they could be the perfect option for more active patients with light incontinence. Despite wide availability, there still is no international standard of performance test for washable incontinence pants. This study aimed to develop performance test methods for washable incontinence pants. We applied the methods of ISO 11948-1: Urine absorbing aids. Part 1: Whole product testing and a standard by Korea Senior Products Association, SPS-KSPA-1014-7240: Urinary incontinence panty to measure maximum absorption volume or urine absorbency, rewet mass, and urine leakage of a washable incontinence pants. The results of the maximum absorption volume or urine absorbency measured were 146.67(±10.95)ml based on rewet mass, 246.67(±41.47)ml based on leakage observation, and 325.48(±9.44)g based on ISO 11948-1. The method in ISO 11948-1 was accurate with the least variation coefficient, but it is far from the real environment of the product use. The urine absorbency measurement utilizing the rewet mass and leakage observation showed larger coefficient of variation, ranging from 10 to 30%, but it seems to be clinically meaningful because it is similar to actual use environments. In this study, brown absorbent paper was used instead of conventional filter paper, and it was much more effective in detecting the rewet and leakage of urine from the incontinence product. Therefore, we proropose to use absorbent paper instead of the existing filter paper in the performance test of urine absorbing pads or urinary incontinence pants. This study showed that each test method has advantages and disadvantages, and further research is needed to develop a performance test method that is similar to the actual use environment and has a reasonably high accuracy.

A Wearable Paper-Based Sweat Sensor for Human Perspiration Monitoring.

The fabrication and performance of a wearable paper-based chemiresistor for monitoring perspiration dynamics (sweat rate and sweat loss) are detailed. A novel approach is introduced to measure the amount of aqueous solution in the order of microliters delivered to the sensor by monitoring a linear change in resistance along a conducting paper. The wearable sensor is based on a single-walled carbon nanotubes and surfactant (sodium dodecylbenzenesulfonate) nanocomposite integrated within cellulose fibers of a conventional filter paper. The analytical performance and the sensing mechanism are presented. Monitoring sweat loss in the human body while exercising is demonstrated using the integration of a wireless reader and a user-friendly interface. By addressing the barriers of cost, simplicity, and the truly in situ demanding measurements, this unique wearable sensor is expected to serve in the future in many different applications involving the on-body detection of biofluids, such as a monitoring tool of dehydration levels for athletes as well as a tool for enhancing the sport performance by providing an accurate recovery of the hydration status in daily exercises.

Fast supercapacitors based on vertically oriented MoS2 nanosheets on plasma pyrolyzed cellulose filter paper

Fast supercapacitors that can be charged and discharged at tens of hertz high frequency are reported using binder-free electrodes of MoS2 nanosheets grown on plasma pyrolyzed cellulose microfiber (pCMF) paper. Rapid plasma pyrolysis was applied to obtain highly conductive carbon fiber sheet from conventional cellulose filter paper to be used as a scaffold, on which MoS2 nanosheets were grown vertically wrapped around carbon microfibers in a hydrothermal reaction. Such binder-free MoS2-pCMF electrode based supercapacitor demonstrated fast-rate performance in an aqueous electrolyte with a cutoff frequency of 103 Hz. A large specific capacitance density of 125 mF cm−2 was also measured. The organic electrolyte cell of these electrodes exhibited a power density of 12.05 W cm-3 at a rate of 15 V s−1. These MoS2-pCMF electrodes were highly stable. In a cycling test at a current density of 10 mA cm−2, the cell maintained its capacitance with trivial degradation in 50,000 cycles.

Cellulose nanofibrils coated paper substrate to detect trace molecules using surface-enhanced Raman scattering

Acquisition of reproducible surface-enhanced Raman scattering (SERS) signals using paper-based SERS sensors is difficult because of the non-uniformity of the paper surface, which possesses a large number of pores and high surface roughness. To overcome the poor reproducibility of paper-based SERS sensors, they were coated with cellulose nanofibrils (CNF) obtained from pulp fibers, which fill the pores and decrease the local height differences on the paper’s surface. The combination of hydrophobic modification and the improved uniformity and smoothness of the surface after CNF coating increased the coverage of silver nanoparticles (AgNPs) in the SERS spots from 87 to 95% and gave a more uniform distribution of the AgNPs on the SERS substrate. When a high magnification lens was used for sensitive molecular detection, the hydrophobic CNF-coated paper-based SERS sensor reduced the relative standard deviation of the SERS intensity and improved the limit of detection for rhodamine 6G. The CNF coating on paper was found to afford a more effective and reproducible paper-based SERS sensor than conventional filter paper.

Hybrid Drug Delivery Patches Based on Spherical Cellulose Nanocrystals and Colloid Titania-Synthesis and Antibacterial Properties.

Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H2SO4. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus. It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents.

Bacterial Nanocellulose‐Based Flexible Surface Enhanced Raman Scattering Substrate

Owing to high purity, simple surface chemistry, and 3D nanofibrous structure, biosynthesized bacterial nanocellulose (BNC) is a highly attractive biomaterial for a wide range of applications. Conventional cellulose‐based laboratory filter paper, adsorbed with plasmonic nanostructures can be employed as a flexible surface enhanced Raman scattering (SERS) substrate. In this work, a BNC film‐based SERS substrate fabricated by gravity‐assisted filtration method is reported. The 3D porous structure of BNC facilitates uniform and dense adsorption of plasmonic nanostructures on the surface and in subsurface regions, which results in large SERS enhancement. Furthermore, significantly lower surface roughness of BNC compared to conventional filter paper results in an excellent uniformity of SERS activity across the entire substrate. Harnessing the smooth surface of BNC, it is shown that BNC‐based SERS substrate serves as an ideal platform for collection, detection, and recognition of bacteria. The 3D plasmonic BNC composites demonstrated here are highly attractive for a broad range of applications including sensing, catalysis, and energy harvesting.

Facile Preparation of Nanostructured, Superhydrophobic Filter Paper for Efficient Water/Oil Separation.

In this paper, we present a facile and cost-effective method to obtain superhydrophobic filter paper and demonstrate its application for efficient water/oil separation. By coupling structurally distinct organosilane precursors (e.g., octadecyltrichlorosilane and methyltrichlorosilane) to paper fibers under controlled reaction conditions, we have formulated a simple, inexpensive, and efficient protocol to achieve a desirable superhydrophobic and superoleophilic surface on conventional filter paper. The silanized superhydrophobic filter paper showed nanostructured morphology and demonstrated great separation efficiency (up to 99.4%) for water/oil mixtures. The modified filter paper is stable in both aqueous solutions and organic solvents, and can be reused multiple times. The present study shows that our newly developed binary silanization is a promising method of modifying cellulose-based materials for practical applications, in particular the treatment of industrial waste water and ecosystem recovery.

Innovative approach to Blood sampling using dried Blood spots. application to Pharmacokinetics and Cytochrome P450 Phenotyping

InnovAtIve APProAch to Blood sAmPlIng usIng drIed Blood sPots. APPlIcAtIon to PhArmAcokInetIcs And cytochrome P450 PhenotyPIng M. Bosilkovska; J. Deglon; A. Thomas; C. Samer; J. Desmeules; and Y. Daali Geneva University Hospitals, Geneva, Switzerland; and University Center of Legal Medicine, Lausanne-Geneva, Switzerland Background: The use of dried blood spots (DBS) has gained in popularity in the last few years over conventional whole blood or plasma sampling for PK or drug monitoring. In order to overcome the impact that haematocrit has on the spreading of the applied drop of blood, precise knowledge of the collected volume is crucial for the determination of drug/metabolites concentrations. Material and Methods: Although the collection of an accurate capillary volume using a volumetric micropipette is simpler than venous blood collection, it still needs to be conducted by trained technicians using dedicated instruments. To simplify this process a new capillary blood collection device has been developed. The prototype integrates a patented microfluidic plate (WO/2013/144743) allowing for accurate volume control and a conventional filter paper card for blood storage. The concentrations and pharmacokinetic profiles of a P-glycoprotein (P-gp) and six cytochrome P450 (CYP) probes and their metabolites obtained with the new sampling device have been compared with a conventional volumetric micropipetting method in a clinical trial including 30 volunteers who have received the Geneva cocktail for CYP and P-gp phenotyping. The quantification was done using a previously validated LC/MS-MS method. Results: Concentrations obtained with the new microfluidic sampling device showed excellent correlation with conventional micropipetting concentrations with slopes values close to 1 (0.91 – 1.03) and determination coefficients R> 0.90 for all of the 13 analysed substances. Sampling could be successfully performed by the volunteers themselves with almost no previous training. Conclusion: DBS technique combined with an innovative sampling device and a sensitive analytical method can be used as a self-test for CYP and P-gp phenotyping The use of this technique can be further enlarged to the quantification of other substances for PK studies and therapeutic drug monitoring.

Chlorophyll fluorescence imaging to facilitate breeding of Bremia lactucae-resistant lettuce cultivars

During recent years, the progressive variability of Bremia lactucae pathogens has increasingly challenged the breeding of new downy mildew-resistant lettuce cultivars. However, conventional plant breeding is a complex and long-lasting process. Especially resistance-testing of newly obtained lettuce lines is still based on visual rating procedures and, hence, labour-intensive and time-consuming. In this manuscript, a straightforward chlorophyll fluorescence imaging (CFI)-based approach will be presented that is capable of objectively and rapidly distinguishing resistant and susceptible butterhead and batavia lettuce lines. To meet the practical demands of plant breeders as close as possible, the proposed technique was based on actually applied conventional visual rating procedures. To rapidly assess potential changes in plant vitality due to successful infections, local distributions and temporal dynamics of the potential maximum photochemical efficiency of electron flow through photosystem II (Fv/Fm) was pixel-wise statistically analysed. Various tests were performed to evaluate the B. lactucae susceptibility in young plants of ten various sensitive and resistant butterhead and batavia lettuce lines. From leaves of one to three months old plants, discs were punched out, inoculated with B. lactucae race BI:18 and incubated at 15°C in a humid chamber for 12h. To optimize conditions for infection, open Polyurethane (PUR) plastic foam were tested as bases of leaf discs in addition to conventional filter paper. Routinely, degree and intensity of infection, extent of contamination with secondary pathogens and occurring leaf damage were recorded by visual rating. In image analyses from CFI, infected leaf discs are mostly characterized by considerable patchy distribution patterns of respective photosynthetic efficiency. Presented results indicate that the proposed approach of pixel-wise analyses of Fv/Fm images is effective and precise to rapidly, objectively and, after improvement of underlay and adaption of inoculation time in darkness, automatically differentiate B. lactucae-susceptible and resistant lettuce cultivars.

Tortuously structured polyvinyl chloride/polyurethane fibrous membranes for high-efficiency fine particulate filtration

Two-tier composite filtration medium exhibiting excellent filtration performance to airborne particulate was prepared by a facile deposition of electrospun polyvinyl chloride (PVC)/polyurethane (PU) fibers on a conventional filter paper support. The tortuous structure and composition of resultant fibrous membranes can be finely controlled by regulating the precursor solution composition. By employing the PU incorporation, the pristine PVC fibrous membranes were endowed with robust tensile strength approaching to 9.9MPa. The plausible correlation between resultant blended fibrous structure and mechanical property of relevant membranes was discussed, and a three-step break mechanism upon the external stress was proposed. Additionally, quantitative pore size and porosity distribution analysis using the capillary flow porometry method has confirmed the tortuous structure of PVC/PU fibrous membranes. Furthermore, the as-prepared membranes with high abrasion resistance (134 cycles) and comparable air permeability (154.1mm/s) showed fascinating filtration efficiency (99.5%) and low pressure drop (144Pa) performance for 300–500nm sodium chloride aerosol particles, suggesting their use as a promising medium for variety of potential applications in air filtration.

A Laboratory Procedure for Measuring High Soil Suction

AbstractMeasurement of soil suction is important for geotechnical and geoenvironmental projects involving unsaturated soils. Most of the methodologies developed for measuring soil suction are limited to low range of suction (<1500 kPa). Those methodologies that can measure high suction (>1500 kPa) are costly, time intensive and require skilled person for suction measurement. Therefore, a simple, cost-effective and relatively less time consuming measurement methodology has been proposed in this study for easy and quick measurement of high range of soil suction. The instrument essentially consists of a commercially available relative humidity sensor secured in a fabricated relative humidity box. The total suction for three soils measured using the proposed methodology has been compared with the conventional filter paper method. The study demonstrates the usefulness and advantage of the proposed cost-effective methodology for measuring high range of soil suction, in a relatively less time.

ARGET ATRP for Versatile Grafting of Cellulose Using Various Monomers

In recent years, cellulose-based materials have attracted significant attention. To broaden the application areas for cellulose, polymers are often grafted to/from the surface to modify its properties. This study applies ARGET (activators regenerated by electron transfer) ATRP (atom transfer radical polymerization) when straightforwardly grafting methyl methacrylate (MMA), styrene (St), and glycidyl methacrylate (GMA) from cellulose in the form of conventional filter paper in the presence of a sacrificial initiator. The free polymer, formed from the free initiator in parallel to the grafting, was characterized by (1)H NMR and SEC, showing that sufficient control is achieved. However, the analyses also indicated that the propagation from the surface cannot be neglected compared to the propagation of the free polymer at higher targeted molecular weights, which is an assumption often made. The grafted filter papers were evaluated with FT-IR, suggesting that the amount of polymer on the surface increased with increasing monomer conversion, which the FE-SEM micrographs of the substrates also demonstrated. Water contact angle (CA) measurements implied that covering layers of PMMA and PS were formed on the cellulose substrate, making the surface hydrophobic, in spite of low DPs. The CA of the PGMA-grafted filter papers revealed that, by utilizing either aprotic or protic solvents when washing the substrates, it was possible to either preserve or hydrolyze the epoxy groups. Independent of the solvent used, all grafted filter papers were essentially colorless after the washing procedure because of the low amount of copper required when performing ARGET ATRP. Nevertheless, surface modification of cellulose via ARGET ATRP truly facilitates the manufacturing since no thorough freeze-thaw degassing procedures are required.

All-Cellulose Composite Prepared by Selective Dissolving of Fiber Surface

An all-cellulose composite was prepared from conventional filter paper by converting a selective dissolved fiber surface into a matrix. The structure and mechanical, thermal, and optical properties of this composite were investigated using X-ray diffraction, a scanning electron microscope, an optical microscope, a tensile test, and dynamic viscoelastic analyses. After optimizing the immersion condition of the filter paper in a solvent, the fibers, with selectively dissolved surfaces, were unified by compression followed by drying. The tensile strength of the composite reached 211 MPa at 25 degrees C, isotropically. This value was comparable or even higher than those of conventional glass-fiber-mat-reinforced composites. The composites possessed a high storage modulus of more than 20 GPa at -150 degrees C, and a storage modulus of the GPa order was maintained up to around 250 degrees C. The good interface is considered to bring optical transparency to this composite. In addition, this composite is composed of sustainable resources and is biodegradable after service, which gives it advantages with regard to disposal, composting, and incineration.

ATRP grafting from cellulose fibers to create block-copolymer grafts.

Cellulose fibers, in the form of a conventional filter paper, have been modified by reacting the hydroxyl groups on the fiber surface with 2-bromoisobutyryl bromide, followed by grafting using ATRP conditions. The papers were first grafted with methyl acrylate (MA), rendering the paper very hydrophobic as reported in an earlier work. The papers were analyzed by gravimetry, FT-IR, ESCA, and AFM. To verify that the polymerization from the surface was "living", a second layer of another, hydrophilic, polymer, 2-hydroxyethyl methacrylate (HEMA), was grafted upon the PMA layer, creating a block-copolymer graft from the fibers. After the layer of PHEMA had been attached, contact angle measurements were no longer possible, because of the absorbing nature of PHEMA-grafted layer. This indicates that a copolymer had indeed been formed on the surface. FT-IR showed a large increase in carbonyl content after the PHEMA-grafting, which further proves that a layer of PHEMA was attached to the PMA layer. This goes to show that the hydrophilic/hydrophobic behavior of a cellulose surface can be tailored by the use of "living"/controlled radical polymerization methods such as ATRP.

Strongyloidiasis--progress in diagnosis and treatment.

Strongyloidiasis is an intestinal parasitic disease caused by Strongyloides stercoralis. Basically, detecting larvae of S. stercoralis in feces makes definitive diagnosis. The ordinary agar plate culture method developed at our department is much simpler to handle and much more sensitive than the conventional filter paper culture method. It is considered to be the most useful method in the diagnosis of strongyloidiasis and in evaluation of the eradicating effect. Among chemotherapeutic agents, thiabendazole representing the benzimidazole compounds is most effective. However, it has a problem in safety, since its adverse effects and liver dysfunction occur with a high incidence, and it can be severe. Regarding the effects of mebendazole, albendazole and ivermectin, a study was conducted which included many patients. A high incidence of liver dysfunction was observed with mebendazole, and eradicating effect was not sufficient with albendazole. Ivermectin is different from benzimidazole compounds in a pharmacokinetic profile. However, ivermectin showed a strong anthelmintic effect with the least toxicity. We therefore consider ivermectin is the most useful drug for the treatment of strongyloidiasis.

Screening of Haematobia irritans irritans (Diptera: Muscidae) Populations for Pyrethroid Resistance-Associated Sodium Channel Gene Mutations by Using a Polymerase Chain Reaction Assay

A polymerase chain reaction (PCR)-based rapid screening procedure was developed to test individual horn flies, Haematobia irritans irritans (L.), for the presence of a specific nucleotide substitution in the sodium channel gene sequence that has been associated with pyrethroid resistance. By a systematic optimization of reaction conditions and judicious choice of PCR primers differing in DNA sequence by a single nucleotide, we identified pyrethroid-susceptible or resistant sodium channel alleles in individual flies. Laboratory and field populations were examined by both the PCR assay and conventional filter paper bioassays with the pyrethroid cyhalothrin to verify that populations containing greater proportions of individuals with the resistant sodium channel allele DNA sequence also had higher bioassay LC50 values. The PCR assay for resistance alleles gave definitive information on the genotype of an individual fly and detected the presence of heterozygous individuals that might serve as reservoirs of resistance genes in field populations.