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A totally implantable watch battery (1.5 V) having 2 cathodes connected with 2 cortical screws of an osteosynthesis plate and one anode in the adjacent tissues gave positive results when used for enhancement of healing in experimentally fractured model.
In the recording of biomedical signals, a significant noise component is introduced by the electrode. The magnitude of this noise is considerably higher than the equivalent thermal noise from the electrode impedance. As the noise in surface electrodes limits the resolution of biopotential recordings, it is important to understand its origin. It was found that the noise mainly originates in the electrolyte-skin interface and that it is highly dependent on the electrode gel used and the skin properties of the test subject. Depending on skin treatment, magnitudes between 1 and 20 microVrms were measured among subjects. When the metal-electrolyte interface was allowed time to stabilise, electrodes of different metals measured face to face all showed a negligibly small noise magnitude (< 1 microVrms). In pre-gelled electrodes, where the metal-electrolyte interface has stabilised, no difference in noise properties was found between Ag-AgCl electrodes and other metals when measured on the skin. In subjects at rest, the contribution of EMG signals to the total noise level was shown to be negligibly small compared with the noise contribution of the electrolyte-skin interface. The magnitude of the noise of electrodes appeared to be inversely proportional to the square root of the area of the electrode on the skin.
An electrode assembly for in vivo recording of the electrical activities of thin muscular layers is described. It comprises an active electrode surrounded by a ring, which avoids the recording of interfering signals. An improved technique for chlorinating the silver electrodes is presented: a partial electrolytic removal of an initial thick deposit is performed. This decreases the impedance, and lowers the ageing degradation of the electrodes in vivo. Recordings of extremely low frequency signals are allowed, whereas standard Ag/AgCl electrodes are inefficient when recording signals in the frequency domain under 0.1 Hz. The technical features which are described can be adapted to any Ag/AgCl electrode developed for in vivo measurements.
The electrochemical noise from dry NASICON-based surface electrodes and pregelled Ag-AgCl electrodes is evaluated in saline solutions and on the skin. The electrochemical noise from the electrode/electrolyte interface is found to be negligible (less than 1 microV peak to peak). On the skin, the noise level is highly dependent on the patient. At high frequencies, the skin/electrode interface noise is equal to 'thermal noise' and can be related to the real part of the skin/electrode impedance. At low frequencies (F < 100 Hz), excess noise is observed that varies as f-2. It is tentatively ascribed to a non-stationary process or noise of electrochemical origin due to the ionic nature of the skin. The contribution of residual EMG signal of low amplitude (5 microV peak to peak) is suggested for electrodes with large surface area.
The purpose of this investigation was to compare the local effects of polyurethane (Tecothane) and silicone tubes with or without silver impregnation in rats. Bacterial colonization or infection of the exit site and/or tunnel were documented and interpreted. All tubes were placed subcutaneously or percutaneously in the neck of 41 Sprague-Dawley rats and guided beneath the dorsal muscles into the peritoneal cavity. The incidence of bacterial abscesses along the implanted tubes was evaluated daily. After 90 days, or earlier if sepsis developed, the animals were killed painlessly and various organs and tissues from the entry site and the catheter tunnel examined histologically. In the group where polyurethane tubes were placed percutaneously, there was no difference in the frequency of abscesses between silver-impregnated and non-impregnated tubes (5/6 with and 5/7 without silver). The only difference noted was in the group with percutaneously placed silicone tubes between those with and without silver. Abscesses only occurred in 2/4 animals in the silver group and in 5/5 animals in the control group. Histological examination showed no difference in either group between infectious and foreign body reactions. Silver particles in subcutaneous, muscle and peritoneal tissue could not be demonstrated.
Argyrophilic grain disease (AGD) is a frequently occurring degenerative illness of the aging human brain. It is accompanied by progressive pathological alterations of the cytsokeleton which are traceable to an abnormal phosphorylation of the microtubule associated tau protein. Histologically, it is possible with the help of suitable staining techniques to identify pathognomonic spindle-shaped cellular inclusions (argyrophilic grains). These cellular inclusions display a typical cortical as well as subcortical distribution pattern. The goal of the present study is the retrospective evaluation of the clinical findings from 53 individuals with neuropathologically demonstrable AGD-related changes of the brain. Nearly one-half of the cases (49%) was classifiable as demented in accordance with DSM IV-criteria. Moreover, the frequency of the dementia increased significantly in relation to the growing severity of the AGD-associated pathological cytoskeletal degeneration. These results confirm the assumption that AGD can cause degenerative changes ranging from cognitive impairment all the way to dementia. They also underscore the necessity of further prospective studies pertaining to the clinical aspects of this still enigmatic disease.
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A novel quantitative method for the determination of proteins in aqueous solutions has been based on the quenching of the resonance scattering light of colloidal silver chloride in the presence of proteins. The detection limits for eight kinds of proteins (BSA, HSA, egg albumin, human gamma-IgG,alpha-chymotrypsin, E. Coli. alpsase, myoglobin, alpha-casein) were at about 8 ng/mL; the linear ranges of the calibration curves were 10-400 ng/mL under optimal conditions,except for human gamma-IgG (20-400 ng/mL), myoglobin (10-300 ng/mL), and alpha-casein (10-300 ng/mL). Three wavelengths (398 nm, 475 nm, 499 nm) were all suitable for the determination and any acidity from pH 3.0 to pH 9.0 could be chosen. A few non-protein substances at high concentration levels interfered with this method, but this problem could simply be overcome by diluting the samples before the assay. Mechanism studies showed that the quenching effect of proteins on the scattering light of colloidal silver chloride was mainly due to the coagulation of AgCl particles retarded by protein. The method was employed for the determination of total protein in human serum with satisfactory results.
Electrophysiological techniques require stable, reversible electrodes for accurate recording. Ag/AgCl electrodes are commonly used in patch-clamp and intracellular recording pipettes, but when these electrodes are exposed to Cl--free media they are no longer reversible and may develop large, unstable offset potentials. We present here a simple electrode holder design that provides a liquid junction between the electrode solution and a KCl-filled reservoir containing the AgCl pellet. This allows an electrode solution of any composition to be used without affecting the reversibility of the electrode, and the liquid junction potentials that develop are small and well defined. Mechanical isolation of the AgCl pellet from the pipette improves long-term stability of the electrode because the AgCl coating is not scraped while changing pipettes. The response time of the holder and its wide-band noise levels are comparable to those of standard holders. For practical experiment durations, the diffusion for KCl from the reservoir down the pipette produces negligible contamination at the tip. Similarly, back diffusion of the pipette contents into the reservoir is also negligible.
OBJECTIVE: To compare the clinical and radiographic treatment outcome of retrograde root filling with either dentin-bonded resin composite (Retroplast, RP) or glass ionomer cement (Chelon-Silver, CS). STUDY DESIGN: A prospective, randomized clinical study of 134 consecutive patients with indication of retrograde root filling of an incisor, canine, premolar, or first molar. Either RP or CS was chosen at random as retrograde filling material. Either material was applied onto the entire resection surface after prepared slightly concave. This preparation technique makes a sealing of the entire resection surface possible and prevents marginal contraction gaps during polymerization. A total of 122 patients were available for 1-year follow-up. RESULTS: After 1 year the proportion of successful cases was significantly higher in the RP group (73%) than in the CS group (31%) (p<0.001). Doubtful healing with a need for a longer observation period was seen in 17% of the RP cases and 19% of the CS cases. The proportion of failures in the RP group (10%) was significantly lower than that in the CS group (50%) (p<0.001). Most of the unsuccessful CS cases failed due to loosening of the retrograde filling. CONCLUSIONS: Dentin-bonded RP applied onto the entire, slightly concave resection surface is a predictable apical sealant characterized by a high success rate. In contrast, retrograde root filling with CS results in an unacceptably high failure rate due to insufficient bonding strength to the concave resection surface.
In situ replacement of infected vascular grafts is an accepted alternative to total graft excision and extraanatomic replacement. Its success relies upon the ability of the newly inserted graft to resist recurrent infection. This study compares the efficacy of two methods used to reduce the risk of graft reinfection: rifampicin soaking versus silver bonding of grafts. The grafts' resistance to infection was tested in vitro in two protocols, each using a panel of seven common bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). The length of time the grafts remained free of organisms was compared between the groups. Both the silver graft and the rifampicin-soaked graft were significantly better than control graft at preventing bacterial growth on the graft surface. The rifampicin inhibited the growth of the gram-positive organisms, including MRSA, significantly better than the silver graft on days 2 and 3 (p < 0.001). Conversely, the silver graft was significantly more effective against the gram-negative organisms until day 4 (p < 0.0001). Both types of graft inhibit the in vitro growth of bacteria more effectively than controls, with rifampicin being most effective against gram-positive organisms and silver being best against the gram-negative organisms.
Effects of new wound dressing bacterial cellulose impregnated with SOD and poviargol (Procel-Super and Procel-PA) and Inerpan hydrogel dressing on the reparative processes in deep dermal burns (IIIa-IIIb degree) in rats exposed to total even irradiation in a dose of 4 Gy were studied. Inerpan and Procel-Super dressings proved to be the most effective under these conditions: they accelerated healing of burn wounds by 17.0 and 5.5%, respectively.
Combination intraarticular administration of Poviargol (0.5 mg/kg) and nicotinic acid (1.0 mg/kg) reduced symptoms of local and general inflammation in rats with adjuvant arthritis. We revealed a decrease in morphological signs of inflammatory degeneration of joint tissue and reduction of metabolic disorders.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.