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PubMedDate not supplied

Comparison of in vitro disc diffusion and time kill-kinetic assays for the evaluation of antimicrobial wound dressing efficacy.

There is a plethora of new silver-containing dressings on the market today. Various manufacturers attempt to show that their dressings are the most efficacious and therefore should be preferentially employed by health care workers based on the results of their in vitro tests. However, there have been no studies that clearly identify which tests are appropriate for comparison purposes. The purpose of this study was to determine which in vitro test is most appropriate for evaluating the antimicrobial efficacy of silver-containing dressings. This was done by testing seven silver-containing dressings and two non-silver-containing topical agents against 17 clinically relevant microorganisms using zone of inhibition assays and time-kill kinetic assays in complex media. The results for the two assays were then correlated to determine whether the methods generated similar results. It was determined that the two methods do not correlate at all. This is most likely a result of the silver interacting with the media in the zone of inhibition test, thus invalidating the results of this test. We therefore conclude that zone of inhibition data generated for silver-containing dressings is of little value when assessing antimicrobial efficacy and that time-kill assays are of greater use.

Administration, Topical↗
PubMed1995

Disulfide bond-forming reaction using a dimethyl sulfoxide/aqueous HCl system and its application to regioselective two disulfide bond formation.

Disulfide bond formation in S-acetamidomethyl (Acm) cysteine-containing peptides by successive treatments with silver trifluoromethanesulfonate (AgOTf) and dimethyl sulfoxide (DMSO)/aqueous HCl is described. An S-Acm cysteine was found to be quantitatively converted into cysteine by deprotection of the Acm group with AgOTf followed by DMSO/aqueous HCl treatment. Under these reaction conditions, no significant side reactions were observed with oxidation-sensitive amino acids such as Met, Tyr and Trp. Oxytocin and a Trp-containing peptide, urotensin II, were prepared by this method. Furthermore, regioselective two disulfide bond formation was found to be feasible by the combination of air oxidation and the AgOTf-DMSO/HCl system. This strategy has been successfully applied to the syntheses of tachyplesin I and endothelin I, which have two disulfide bonds and a Trp residue in the molecule.

Amino Acid Sequence↗
PubMed1984

Silver staining of DNA synthesizing cells in the neural tube of chick embryos.

I report a study by light microscopy of the spinal cord of early chick embryos stained with the ammoniacal silver carbonate solution of Del Rio Hortega. Cell nuclei are stained in a selective fashion and two classes of nuclei - dark and pale - can be distinguished in the neuroepithelium. Neuronal nuclei also show a characteristic staining pattern. A radioautographic study after [3H] thymidine incorporation has shown that it is the dark neuroepithelial nuclei that are engaged in DNA synthesis. Dark nuclei disappear after administration of cytosine arabinoside, supporting the association between DNA synthesis and silver staining of neuroepithelial nuclei.

Animals↗
PubMed1978

An analysis of the bovine genome by density-gradient centrifugation. Preparation of the dG+dC-rich DNA components.

The dG+dC-rich fractions obtained by density gradient centrifugation of bovine DNA in Cs2SO4/BAMD [J. Cortadas, G. Macaya & G. Bernardi (1977) Eur. J. Biochem. 76, 13--19] were centrifuged in Cs2SO4/Ag+ density gradients. These experiments led to the preparation of the DNA components which had been detected (by analytical centrifugation in CsCl) in the Cs2SO4/BAMD fractions, and also of DNA components which had identical behaviors in Cs2SO4/BAMD gradients and identical buoyant densities in CsCl. A total of eight satellite components and 11 minor components, accounting for 23% and 4% of the bovine genome, respectively, were thus isolated and charcterized in their relative amounts and buoyant densities. The implications of these results on the interpretation of renaturation kinetic data on the bovine genome are discussed.

Animals↗
PubMed1989

Method of measuring liquid junction potentials in small (nanolitre) droplets of biological fluids.

1. A method is described which allows the determination of liquid junction potentials between biological fluid samples of less than 1 nL with a reproducibility of 10%. This was achieved by use of a micro-method and the use of 3% agarose added to the electrolyte in the measuring electrodes. 2. Validation was performed with a modified flowing boundary method and the system was also tested using a solution containing divalent ions. Liquid junction potential between surface fluid from rat kidneys and harvested renal proximal tubular fluids was -0.62 +/- 0.11 mV (mean +/- s.d., n = 66).

Body Fluids↗
PubMed1990

Issues in biometrics: offset potentials and the electrical stability of Ag/AgCl electrodes.

There has been a continuing interest in many areas of psychophysiological research in the quantification of slow wave bioelectric potentials recorded from the surface of the skin. However, surprisingly little research has focused specifically on methods for stabilizing and minimizing the offset potentials of the sintermetallic Ag/AgCl surface electrodes commonly used in such noninvasive bioelectric measurement. To provide empirically based recommendations in this regard, we contrasted the effects of three common storage methods (air dry vs. saline vs. carbon rod) on the two distinct types of Ag/AgCl surface electrodes (sintermetallic vs. electrolytic) under simulated experimental conditions. The obtained results confirm that minimum offset potentials and maximum stability for electrolytic Ag/AgCl electrodes are obtained when they are stored in a 0.9% NaCl solution with their leads shorted together and connected in parallel to a carbon rod partially immersed in the solution (cf. Cooper, 1956). In addition, the pattern of results suggested that the inter-session unshorted storage of sintermetallic electrodes in a mild saline solution is to be recommended over either shorted saline storage in parallel with a carbon rod or unshorted dry storage.

Electric Conductivity↗
PubMed2001

Laboratory strength of glass ionomer and zinc phosphate cements.

PURPOSE: The present in vitro study examined 3 mechanical properties, namely compressive, flexural, and diametral tensile strength, of various commercially available cements and core materials as a function of time after mixing. MATERIALS AND METHODS: The examined materials were 2 cermet cements (Ketac Silver [ESPE, Seefeld, Germany] and Chelon Silver [ESPE]), 1 metal-reinforced glass ionomer cement (Miracle Mix [GC Dental Industrial Corp, Tokyo, Japan]), 2 conventional glass ionomer cements (Ketac Bond [ESPE] and Ketac Cem [ESPE]), 1 standard cure zinc phosphate cement (Harvard Cement [Richter and Hoffmann, Berlin, Germany]), and 1 zinc phosphate cement with the addition of 30% silver amalgam alloy powder (Harvard Cement 70% with Dispersalloy 30% [Richter and Hoffmann/Johnson and Johnson, East Windsor, NJ]). Properties were measured using a universal testing machine at 15 minutes, 1 hour, and 24 hours after first mixing. RESULTS: Compressive strengths varied widely between the 3 times of measurement from 5.8 +/- 6.6 MPa for Ketac Cem to 144.3 +/- 10.2 MPa for Ketac Silver. Twenty-four hours after mixing, the Bonferroni test showed significant (p <or= .01) differences between Ketac Silver and all other materials tested. Diametral tensile strengths ranged widely from 4.4 +/- 0.9 MPa for Ketac Cem to 11.5 +/- 2.2 MPa for Chelon Silver. At 15 minutes, 1 hour, and 24 hours after first mixing, the analysis of variance did not show any significant differences between Ketac Silver, Chelon Silver, and Miracle Mix. The 3-point flexural strength of Ketac Silver showed, at 15 minutes with 13.5 +/- 3.9 MPa and at 24 hours with 27.2 +/- 7.4 MPa, the highest values. CONCLUSIONS: Setting time influences the mechanical properties of the materials tested in this study. Ketac Silver, a glass ionomer cement reinforced with sintered glass-silver particles, showed the highest mechanical properties of the examined materials.

Analysis of Variance↗
PubMed1998

Simultaneous recordings of the monophasic action potential with silver chloride- and Ir-coated electrodes.

Ag/AgCl and Ir-coated electrodes allow the recording of the monophasic action potential (MAP) due to their electrical properties like non-polarisability. This study investigates the correlation of MAP recorded with both types of electrodes. In 20 mongrel dogs (18 +/- 6 kg) an Ag/AgCl and an Ir-coated catheter (Ir) were placed endocardially in the apex of the right ventricle. The effects of isoproterenol and verapamil were investigated during spontaneous rhythm and stimulation simultaneously recorded with both types of electrodes in 10 dogs without AV-node ablation. The correlation at different heart rates were investigated in 10 other dogs with complete AV-block. The morphology and amplitudes of MAP were comparable (AgCl: 15 +/- 7 mV; Ir: 13 +/- 8 mV). Following an i.v. bolus of 2 micrograms/kg isoproterenol the spontaneous rate increased (175 +/- 18 to 245 +/- 25 bpm). During stimulation with 250 ms cycle length the duration shortened (MAPd90: AgCl: 160 +/- 11 to 130 +/- 12 ms; Ir: 154 +/- 18 to 128 +/- 15 ms). The alterations reversed after 20 min. An i.v. bolus of 0.2 mg/kg verapamil decreased the spontaneous rate (167 +/- 11 to 104 +/- 23 bpm) and lengthened the MAPd90 (AgCl: 182 +/- 14 to 220 +/- 13 ms; Ir: 174 +/- 16 to 216 +/- 21 ms) at 300 ms stimulation. The correlation between the MAPd90 of both lead types was r = 0.98 during all measurements. Under the effect of beta-agonist and Ca(2+)-antagonist medication MAP showed a strong correlation recorded with both types of electrodes. Thus, both leads allow the recording of MAP but only the Ir-electrodes with their long-term stability are implantable and allows us to control the effects of drugs with implantable devices.

Action Potentials↗
PubMedDate not supplied

Infraciliary bands in the rumen ophryoscolecid ciliate Ostracodinium gracile (Dogiel, 1925), observed by light microscopy.

Morphological features of the rumen ciliate Ostracodinium gracile (Dogiel, 1925) are described from pyridinated silver carbonate-impregnated specimens. Ostracodinium gracile has a characteristic arrangement of infraciliary bands not present in other ophryoscolecid ciliates. Buccal infraciliature is composed of three polybrachykineties. The adoral polybrachykinety does not completely encircle the circumference of the vestibular opening, but arches ventrally from its right to left side. The dorsoadoral polybrachykinety extends laterally along the dorsal side of the vestibular opening. The vestibular polybrachykinety extends along the dorsal wall of the long tubular vestibulum. Dorsal infraciliature consists of the dorsal polybrachykinety that extends laterally along the dorsal side of the body. During binary fission, four primordia, that is ventral, right, left, and dorsal primordia, form in the stomatogenic field and develop into the adoral, dorsoadoral, vestibular, and dorsal polybrachykineties of the opisthe, respectively.

Animals↗
PubMedDate not supplied

Light microscopic observations of infraciliature and morphogenesis in six species of rumen Ostracodinium ciliates.

Infraciliature and morphogenesis of six rumen ciliates, Ostracodinium mammosum, O. munham, O. dilobum, O. rugoloricatum, O. iwawoi, and O. tiete are described from pyridinated silver carbonate-impregnated specimens. These six Ostracodinium have a similar polybrachykinety arrangement, distinct from that of other ophryoscolecid ciliates and intermediate between those of O. gracile and 0. damaliscus. Buccal infraciliature is composed of three polybrachykineties, a kinety loop, and paralabial kineties. Small dorso-adoral polybrachykinety, slender vestibular polybrachykinety, and kinety loop are characteristic. Dorsal infraciliature consists of the dorsal polybrachykinety that extends laterally along the dorsal side of the body. Morphogenesis is different from that of O. gracile, because the right end of ventral primordium extends dorsally to grow into a right primordium without separation.

Animals↗
PubMedDate not supplied

Redescription of Psilotricha acuminata Stein, 1859 and revisions of the genera Psilotricha and Urospinula (Ciliophora, Hypotrichida).

Psilotricha acuminata was described by Stein in 1859 as the type species of the ciliate genus Psilotricha Stein, 1859. The ciliate has rarely been found since, and its infraciliature has never been described with the aid of silver-impregnation techniques. We have found P. acuminata Stein, 1859 in soil samples from upland grassland in Scotland (U.K.). Living and healthy organisms of P. acuminata are oblong in outline, and dorso-ventrally compressed. They closely resemble ciliates of the genus Euplotes. The main morphological features used for identification of P. acuminata are the very long and sparse cirri, and the two macronuclei. When the ciliate crawls, the cirri appear stiff and directed backwards. Specimens observed from the ventral side have a protruding anterior end, a rounded or acuminate posterior pole, and a "beak-like" projection to the left side of the posterior end. The ciliate shares characters with the Euplotidae (body shape and reduced ciliature) and with the Oxytrichidae (marginal rows, macronuclei, reduced number of transverse cirri). Because the arrangement of the silver-impregnated infraciliature was unknown, and as the only description of the ciliate was that of Stein (1859a, b), the genus Psilotricha became confused with other hypotrich genera, especially Urospinula Corliss, 1960. Here we provide a full redescription of P. acuminata based on living and silver-impregnated specimens, and a revision of the genera Psilotricha Stein, 1859 and Urospinula Corliss, 1960. We resurrect the genus Urospinula, and give an emended diagnosis for both genera. The species now included within the genus Psilotricha are P. acuminata Stein, 1859 (type species); Psilotricha viridis (Penard, 1922) Kahl, 1932; and Psilotricha geleii (Gelei, 1954) Stiller, 1974. Psilotricha viridis sensu Kahl, 1932 and Psilotricha dragescoi Grolière, 1975 are considered incertae sedis.

Animals↗
PubMedDate not supplied

Morphology and infraciliature of a marine scuticociliate with a polymorphic life cycle: Urocryptum tortum n. gen., n. comb.

A new genus and species combination are proposed for Urocryptum tortum n. gen., n. comb., a scuticociliate with a polymorphic life cycle. This marine ciliate was isolated from a sample taken at Gokasho Bay in Mie Prefecture (Japan). Specimens from different phases of the growth cycle were examined in vivo and with two silver staining techniques. Three life-history stages were observed: an exponential growth phase stage (trophont), a stationary phase stage (tomite), and finally a resting stage (cyst). The exponential growth form is laterally flattened and ovoid; it has 20-24 somatic kineties (SK) and a typical complement of scuticociliate oral structures. Polykinetid 1 (Pk1) has two longitudinal files of 6 kinetosomes (Ks); sometimes one or two additional kinetosomes are located anteriorly. Polykinetid 2 (Pk2) has two files of 6 or 7 Ks; a third file of three widely spaced kinetosomes is located on its right side, as well as a small curved row of 5 Ks positioned on the right hand side of the posterior end of Pk2. Polykinetid 3 (Pk3) has 3 rows of 4, 5, and 7 Ks's perpendicular to the haplokinety (Hk) or paroral membrane. The stationary growth phase cell is spindle-shaped and has a similar number of SK that are much more closely spaced than in exponentially growing specimens. Oral infraciliary structures are reduced in size, having fewer kinetosomes and being positioned more anteriorly in the cell. Pk1 is composed of two files of 5-Ks, Pk2 has only two files of 6-7 Ks, and Pk3 has two to three rows of 3-4 Ks. The Hk is displaced anteriorly and becomes straight, losing the shape typical of exponential growth phase cells. Cysts are pyriform with a wide cyst wall; no infraciliary structures were visible.

Animals↗
PubMedDate not supplied

Light microscopical observation of infraciliary bands of Eodinium posterovesiculatum in comparison with Entodinium bursa and Diplodinium dentatum.

Morphological features of the four morphotypes of the rumen ciliate, Eodinium posterovesiculatum, are described from pyridinated silver carbonate-impregnated specimens. Infraciliary bands are compared with those of Entodinium bursa and Diplodinium dentatum. In Entodinium bursa, the adoral polybrachykinety is "C" shaped and the vestibular polybrachykinety extends from the dorsal extremity of the adoral polybrachykinety as in other Entodinium species. In Diplodinium dentatum, the adoral polybrachykinety encircles most of the circumference of the vestibular opening and the vestibular polybrachykinety extends from the inner side of the adoral polybrachykinety as in other Diplodinium species. Infraciliary bands in Eodinium posterovesiculatum encircle the whole circumference of the vestibular opening and are, therefore, distinct from Entodinium, Diplodinium and other ciliates in the family Ophryoscolecidae. In Eodinium posterovesiculatum, the adoral polybrachykinety and the anterior part of the vestibular polybrachykinety encircle the vestibular opening. The wide and long vestibular polybrachykinety extends along the right wall of the tubular vestibulum and is bordered by a kinety. Kinetids in the central part of the vestibular polybrachykinety are randomly disposed. The genus Eodinium is valid because of this characteristic polybrachykinety arrangement in Eodinium posterovesiculatum.

Animals↗
PubMed1990

Clinical pilot study on new dental filling materials and preparation procedures in developing countries.

Conservative dentistry in developing countries often poses a problem because of lack of expensive dental equipment. This survey was undertaken to test two more appropriate filling materials in vivo. In 94 secondary school students (in Mzuzu, Malawi) with two or more cavities, one cavity was prepared in the conventional way using drilling equipment and then filled with amalgam, and one cavity was prepared using hand instruments only and filled with either cermet ionomer or "miracle mix". Models of the filled teeth (99 amalgam, 53 "miracle mix", 54 cermet ionomer; all of them Class 1) were made and evaluated by three examiners after 6 months and after 1 yr. The fillings were given a score on a four-point scale. One year later all types of filling materials had significantly decreased in quality, but only five fillings (one amalgam, one "miracle mix", and three cermet ionomer) needed replacement. Compared to the amalgam filling in the same mouth, more cermet ionomer and "miracle mix" fillings performed poorly, but these differences were not statistically significant after 1 yr. Both cermet ionomer and "miracle mix" are very promising alternatives for Class I tooth cavities in areas without dental equipment.

Adolescent↗
PubMed2006

A case of argyria after colloidal silver ingestion.

BACKGROUND: Argyria is often considered an entity of the past, one which has largely disappeared with the cessation of silver usage in oral medications. However, with the practice of colloidal silver ingestion in current "alternative health" treatments, argyria should be considered in the differential diagnosis of blue-gray hyperpigmentation. METHODS: A single case report with clinicopathological correlation. RESULTS: Histological examination of skin biopsy specimen, which showed perieccrine brown-black granules, verified that colloidal silver rather than a prescribed medication was the source of the patient's dyspigmentation.

Administration, Oral↗