Ergonomic design and evaluation of the handle for an endoscopic dissector

The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices.

Practitioner Summary: The endoscopic dissector handles were designed with increased contact area and more suitable insertion angle between the fingers and thumb and the eye rings. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability.     

Microangiopathic hemolytic anemia and thrombocytopenia in a child with atrial septal defect and pulmonary hypertension

We found that exposure to room temperature (RT/21 degrees C) causes apoptosis in HL-60 cells. Here we characterized RT-induced apoptosis in HL-60. After exposure to RT, apoptosis starts within 6 h and more than 80% of the cells underwent apoptosis within 20 h. All cells, however, were committed to apoptosis after 16 h and no viable cells could be recovered. The caspase-1 inhibitor (YVAD-CHO) effectively blocked apoptosis, whereas the caspase-3 inhibitor (DEVD-CHO) did not. About 20% of newly obtained early passage HL-60 cells (passage 10) also underwent apoptosis by RT treatment. These data suggest that some population in HL-60 which responds to RT with apoptosis became dominant during passaging.     

Enhancement of in vitro skin permeation of verapamil

A number of compounds including aliphatic esters, alkanols and amides were investigated for their ability to enhance the in vitro permeation rate of verapamil across hairless mouse skin. While several of them did enhance the permeation rate, the best results were obtained with the lauric acid derivatives. On analysis of the permeation rate data it was found that while most of the compounds increased the solubility of verapamil in skin and hence its partition coefficient from the delivery system, the lauric acid derivatives also increased its diffusivity in skin. Permeation of verapamil from delivery systems containing these lauric derivatives was further investigated through delipidized and stripped skin. It was found that most of these derivatives enhanced the permeation of verapamil across both whole and delipidized skin, indicating that in addition to their action on the skin lipids, they must also have some effect on the proteins in the stratum corneum.     

Surface properties of polymers prepared from trimethylsilyldimethylamine and hexamethyldisilazane by glow discharge polymerization

Polymers prepared from the monomers trimethylsilyldimethylamine and hexamethyldisilazane by glow discharge polymerization were analysed by elemental analysis and infrared spectroscopy, and some surface properties were investigated. Although the polymers formed from both monomers have similar chemical structures involving CH₂, CH, Si---CH₃, Si---CH₂---CH---₂---Si, Si---O---Si, and Si---O---C groups, there is a significant difference in nitrogen residues. The nitrogen residues in polymers formed from trimethylsilyldimethylamine exist mainly as amide groups, and the residues in the polymers from hexamethyldisilazane exist as disilazanyl groups. This difference is evident in the surface energy, especially in the polar contribution. The relative ratio of polar and to dispersive contributions to the surface energy is higher for the polymers from hexamethyldisilazane (0.6) than for those from trimethylsilyldimethylamine (0.3). Adhesion between these plasma films and polymer substrates subjected to modification was also examined.     

Adhesion between polymer substrates and plasma films from tetramethylsilane and tetramethyltin by glow discharge polymerization

Adhesion between various polymer substrates and plasma films, which had been prepared from either tetramethylsilane or tetramethyltin by glow discharge polymerization and deposited on the surface of the polymer, was evaluated by the Scotch tape test and by lap-shear strength. It was found that the plasma films exhibited fairly good adhesion to the polymer substrates (with the exception of polypropylene). The position where failure occurred was determined by X-ray fluorescence analysis, scanning electron microscopy and energy diffractive X-ray analysis. This position was at an inner layer of the plasma film (cohesive failure of plasma film), within the polymer substrate (material failure of polymer) or at the interface between polymer substrate and plasma film (adhesive failure) depending upon the polymer substrate. These results indicate an important aspect of durability of surface modification by glow discharge polymerization.     

Kinetics and Thermodynamics of Drug Permeation Through Silicone Elastomers (II) Effect of Penetrant Lipophilicity

The permeation of testosterone analogs through silicone membranes was studied. The variation in the lipophilicity of testosterone molecules was accomplished by the addition or elimination of methyl group and the formation of ester. Furthermore, the effects of replacing one of the CH₃ groups on the dimethylsiloxane unit in the silicone polymer chains by a polar CH₂CH₂CF₃, group, which changes polymer characteristics and thus affects the membrane permeability, was investigated as well. It was found that potential which might prevent flocculation altogether. This can lead to caking. The lowest concentration effective in prevent ing coagulum formation should be used.

Suspensions made from a fluid aluminum hydroxide concentration were easy to redisperse after six weeks of storage. The sedimentation volume was 0.64. Addition of 0.2% xanthan gum raised the sedimentation volume to a value of 1.0. There was no evidence of coagulum formation in this system.     

Control of Rate of Solute Transport in Newly Developed Portable Agar Gel Blood Purification System

Ablood purification module was developed with edible agar or Gelrite, in which activated charcoal was dispersed. Tap water (or normal saline) was boiled, and agar (or Gelrite) powder was dissolved in it. The solution was hardened with no additive or activated charcoal in a plastic cylindrical hard shell with a perforated bottom plate to assemble module A (agar only), module AC (agar with various amounts of charcoal), or module GC (Gelrite with various amounts of charcoal), respectively. The hardened gel was thrust with a plastic straw 21 times in the flow direction. Aqueous test solution was prepared for device evaluation. Bromophenol blue (BPB) concentration decreased only by 10% with module A, whereas it gradually decreased according to the amount of activated charcoal dispersed in the agar with module AC; moreover, it reached its lower limit found by direct use of the same amount of intact activated charcoal. Module GC was shown to remove creatinine continuously from bovine whole blood. A portable artificial kidney system may be constructed by combining these modules with a small hemofilter for removing excess water.     

Vinyl polymerization: 414. Polymerization of vinyl monomer initiated by poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride

The polymerization of vinyl monomer initiated by an aqueous solution of poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride (poly(Q-DMAEM-CI) has been carried out at 85°C. The effects of the amounts of vinyl monomer, poly(Q-DMAEM-CI) and water on the conversion of vinyl monomer have been studied. The overall activation energy in the polymerization of MMA is estimated as 41.9 kJ mol^?1. The polymerization proceeds through a radical mechanism. The location in which the polymerization occurs is discussed. The selectivity for vinyl monomer is explained by ‘the concept of hard and soft hydrophobic areas and monomers’.     

Thermal degradation of poly(diethyl vinylphosphonate) and its copolymer

Thermal degradation of poly(diethyl vinylphosphonate) and diethyl vinylphosphonate/vinyl alcohol copolymer was investigated using thermogravimetry, infra-red spectroscopy and g.c.-mass spectrometry. For poly(diethyl vinylphosphonate), little chain scission occurred and the high stability may be attributed to POP crosslinkages between phsophonate units. With the diethyl vinylphosphonate/vinyl alcohol copolymer, the presence of hydroxyl groups in the polymer chains inhibited the formation of the POP crosslinkages. The main degradation products from the copolymer were aldehydes having the general formula HC(O)(CHCH)_nCH₃ and methyl ketones having the formula H₃CC(O)(CHCH)_nCH₃ and CH₃C(O)(CHCH)_nCHCH₂, where n = 1, 2, 3. The introduction of phosphonate unit into poly(vinyl alcohol) is less effective than that of phosphate unit in enhancement of thermal stability.