Silver Ring Research Articles

A fetal lamb model of partial urethral obstruction: Experimental protocol and results

The functional effects of bladder outlet obstruction in the developing urinary tract are well recognized in patients born with posterior urethral valves, in whom a spectrum of bladder dysfunction has been described. To better understand the changes occurring in the partially obstructed developing lower urinary tract, a fetal lamb model of partial urethral obstruction was developed. Fetal lambs at 90 days' gestation underwent surgical placement of a silver ring (ex utero) at the level of the proximal bladder neck, with concomitant ligation of the urachus. Control animals underwent urethral ligation only. The lambs were then allowed to go through normal gestation, and ewes wer delivered spontaneously. The animals were studied between 2 and 7 days after birth. The postmortem examination showed that the ring was just distal to the bladder neck, around the proximal urethra. This resulted in gradual, partial occlusion of the urethra. Bladder weights, bladder wall thickness, and bladder capacity were significantly increased in the partially obstructed animals as compared with the controls. There was little or no upper tract dilatation in the obstructed group. This animal model, the first to produce gradual outflow obstruction in the fetus, provides a reporducible model of partial urethral obstruction. The model can be used to assay the biochemical and physiological changes found in the developing urinary tract of fetal lambs submitted to intravesical obstruction.

Detrusor hyperplasia and expression of "immediate early" genes with onset of abnormal urodynamic parameters.

To determine the stimulus for growth of the detrusor with a pathophysiological obstruction to the urinary stream, we studied urodynamic parameters, detrusor weight, detrusor DNA content, and the expression of early growth-related protooncogenes in a model of gradual onset bladder outflow obstruction and reversal of obstruction. Silver jeweler's jump rings were placed loosely round the urethra of immature guinea pigs, allowing an obstruction to develop gradually with animal growth. At 1, 2, 4, and 8 wk after surgery, animals were killed after urodynamic studies under urethan anesthesia. Bladders were removed, and mucosa-free detrusor was weighed and frozen for assay of DNA content and expression of c-fos and c-myc protooncogenes. Results were compared with sham-operated age-matched control animals. One week after surgery there was no change in the urodynamic parameters, detrusor weight, or DNA content. At 2, 4, and 8 wk after placement of the silver rings, animals developed obstructive voiding patterns, an increase in detrusor weight, and total DNA content. The onset of obstructive voiding patterns correlated with transient increased levels of c-fos and c-myc mRNA by Northern blot analysis. Autoradiography of in vivo [methyl-3H]thymidine-labeled detrusor muscle from obstructed animals showed myocyte DNA synthesis and mitosis, implying myocyte hyperplasia. After removal of the silver ring, the obstructive voiding patterns resolved and detrusor weight and DNA content returned to levels of the control animals. These results suggest that in the guinea pig bladder subjected to a gradual onset outflow obstruction, detrusor growth is initiated by the development of obstructive voiding patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

The electrochemical reduction of halothane: II: reaction in the presence of oxygen

The electrochemical reduction of mixtures of the inhalation anaesthetic halothane and oxygen was studied on silver and gold disc electrodes. A silver ring downstream from the disc electrode was used to monitor the flux of bromide ion, a product from the halothane reaction. Experiments at pH 13 show significant ring currents due to reaction of oxygen species; this is not so at pH 11, allowing deconvolution of the combined oxygen and halothane response. The oxygen and halothane reactions are shown to occur independently, with no cross-reaction between the oxygen and halothane species and no discernible change in the oxygen or halothane reduction reaction kinetics and mechanism. Concentrations of halothane and oxygen were measured accurately using this novel technique in the concentration range required for a clinical sensor.

Performance of a k-band superconducting annular ring antenna

Superconducting annular ring antennas operating in the TM12 mode at 21 GHz are designed and fabricated on a lanthanum aluminate substrate using a YBCO high-temperature superconducting thin film. The efficiencies and far-field antenna patterns are measured and compared with an identical antenna patterned with silver. The resonant frequencies and experimental far-field patterns agree well with published models, and efficiency measurements show a maximum improvement of 6 percent at 20 K in the efficiency of the HTS antenna when compared to the silver ring at the same temperature.

A “Wet and Measure” Polarographic Device/Sensor Suitable for Both Pure and Applied Research

The “wet and measure” (WAM) polarography requires only a thin layer/film of solution (about 0.025 ml, as a disk of thickness <0.15 cm) held by surface tension at the dropping (or hanging) mercury electrode via a silver ring electrode. The current‐voltage curves obtained by the WAM method are reproducible and are the same as those obtained by dipping the electrodes into the solution. Also, the oxygen maximum obtained in the bulk can be reproduced by the WAM method by using capillaries with small drop times.

An experimental model of detrusor instability in the obstructed pig.

Bladder outflow obstruction was produced in 18 young male pigs using either a silver ring or a silk ligature placed around the proximal urethra. Normal growth of the animals resulted in progressive obstruction. This was monitored by urodynamic studies in conscious animals, using either long-term indwelling bladder cannulae or by intermittent suprapubic catheterisation. At urodynamic assessment 3 to 5 months later, the obstructed pigs voided at an elevated pressure and with a diminished flow rate compared with control animals. Sixty-four per cent of the obstructed pigs developed detrusor instability, with spontaneous contractions exceeding 15 cm H2O during bladder filling; another 14% had decreased bladder compliance. In control animals the filling cystometrogram was stable, with little pressure rise during filling and no spontaneous contractions. This animal model provides the opportunity to study the physiological changes responsible for the development of detrusor instability in the obstructed bladder. It may also be useful for evaluating new treatment regimes for detrusor instability.

Cardiac hypertrophy in rats after supravalvular aortic constriction. I. Size and number of cardiomyocytes, endothelial and interstitial cells.

The ascending aorta of 22 adult male Sprague-Dawley rats was constricted with a silver ring, and 25 animals were subjected to a sham-operation. The hearts, including the main arteries, were fixed by retrograde perfusion 3, 7, 14, 21 and 35 days after the operation. The cross-sectional area of the aorta was reduced by the constriction to an average of 20% of the values found after sham-operation. Twenty-one days after the constriction the weight of the left ventricular myocardium including the septum was increased 1.7-fold compared with controls. No further increase in weight was observed 35 days after the operation. The relative volumes of the tissue components remained largely constant in the subepicardial myocardium. In the subendocardial myocardium, however, the volume fraction of interstitial and, to a lesser extent, of endothelial tissue was significantly increased. Twenty-one days after constriction the estimated total volumes of the different myocardial components per left ventricle were increased 1.7-fold for heart muscle parenchyma, 1.8-fold for endothelial tissue, 2.9-fold for interstitial tissue, and 1.3-fold for capillary lumina compared with controls. At 35 days, only the interstitial tissue showed a further increase to 4.8-fold of control values. The mean cardiomyocyte volume was increased after aortic constriction in proportion to the increase in left ventricular weight, i.e. 1.7-fold over controls at 21 days. After 35 days its value was 29,500 +/- 790 micron 3 in rats subjected to aortic constriction compared with 16,800 +/- 640 micron 3 in controls. At this time the estimated number of cardiomyocytes per left ventricle showed no significant differences between experimental animals (2.9 X 10(7)) and controls (3.1 X 10(7)). Endothelial and interstitial cells were not only increased in average single cell volume (1.3-fold and 2.0-fold, respectively), but also in number per left ventricle (1.4-fold and 2.7-fold, respectively). Two-dimensional parameters indicated that during hypertrophy the capillary supply lagged behind the overall mass increase but achieved control levels on termination of hypertrophic growth at 35 days. These results show that even in pronounced hypertrophy the increase in mass of the myocardial parenchyma in the rat is due exclusively to an enlargement of cardiomyocytes (hypertrophy), whereas in endothelial and interstitial tissues enlargement of cells as well as increase in cell number (hyperplasia) also plays a role.

High Current Brush Material Development, Part II: Metal- Solid Lubricant Coated Wires

The preparation and testing of an electrical contact material, metal-solid lubricant coated copper wires for fabrication of multielement high current brushes, are described. The composite coating consisted of a metal, copper or silver, and an overall 1-5 weight percent (wt %) of a fine solid lubricant powder (graphite, WS 2, or WSe2) evenly dispersed and well oriented in the metal matrix. The coatings were obtained by an electrolytic codeposition technique. By sliding a bundle of the coated wires against a rotating silver or copper slip ring at constant speed of 16.75 m/s, the sliding characteristics-- contact voltage drop and friction of the testing system-were measured as a function of current density up to 12.4 MA/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in several different gas environments. Several brush life tests were made at 12.4 MA/m 2. Results indicate that the coated wire possesses high currentcarrying capability under a wide range of environmental conditions. The tests also showed that vapor lubrication is applicable to all solid lubricants with lameilar structure for reduction of wear rate. A tribochemical background of the sliding system is discussed.

Pulp and Paper Mills in Japan (29)

Yufutsu Mill has been producing various kinds of high grade paper with its intergrated pulp and paper production facilities since 1943. It succeeded in producing 100% hardwood BKP, a first in Japan, and has put “Silver Ring”, our company's highly approved brand of fine paper, onto the world market. The mill has grown into quite a modernized giant through the construction of a coated paper production facility and a new paper production machine, and the rebuilding of the pulp production facility.Yufutsu Mill's advantageous location in the seaside indnstrial area of Tomakomai and its huge land area (5.35 million m2) are just a couple of the promising aspects for the future.Many plans to make the mill more attractive are either under construction or consideration.

A Newly Found Inscription on a Pair of Silver Bracelets from Castlethorpe, Buckinghamshire

In about 1827 a small hoard of coins and jewellery was found whilst ploughing at Castle-thorpe, Buckinghamshire. The hoard consisted of a pair of silver bracelets, a silver ring with a cornelian intaglio showing Bonus Eventus, and silver and bronze coins, the latest of which belonged to the reigns of Antoninus Pius (138–161) and Verus (161–169). The hoard had been contained in a ‘small black urn’ which was not recovered at the time. During a recent detailed study of the jewellery, which is now in the British Museum, it was observed that the bracelets were inscribed.

Vaginal impedance measurement used for mating in the rat.

An apparatus consisting of 2 silver ring electrodes attached to a plastic rod and connected to a transistor indicator was used to measure electrical impedance changes in the vagina of rats. A statistically significant increase in electrical impedance occurred at proestrus. By determining when this peak occurs, the optimal time for pairing can be established. In paired animals the absence of the peak provides a reliable means of diagnosing pregnancy.

Vaginal impedance measurement used for mating in the guinea-pig.

A method for determining the phase of the oestrous cycle by measuring the electrical impedance of the vaginal mucous membrane was examined in the guinea-pig. The apparatus consisted of silver ring electrodes attached to a plastic rod and connected to a transistor indicator. A cyclic increase in impedance was found, and significantly higher values were recorded during the phase of increase (proestrus) than at other times of the cycle. By determining this peak the right time for pairing can be chosen. Conversely, the disappearance of this cyclic culmination in impedance pointed to early pregnancy with a high degree of reliability.

Penile pressures and muscle activity associated with erection and ejaculation in the dog.

A needle-tipped polyvinyl catheter or subminiature pressure transducer was implanted in the corpus cavernosum penis (CCP), corpus spongiosum penis (CSP), or bulbus glandis to determine the pressure during coitus in 42 dogs. Silver ring electrodes were implanted in the ischiocavernosus (IC) and bulbospongiosus (BS) muscles to monitor the electromyographic (EMG) activity of these muscles. The CCP pressure increased from 26 mmHg in the quiescent state to 161 mmHg at mild erection of the penis in the presence of a receptive female. During the intromission phase of coitus, the mean peak CCP pressure was 5,296 mmHg in the dogs with implanted catheters and 7,434 mmHg in the dogs with implanted transducers. The CCP pressure peaks during intromission were more in phase with the contractile activity of the IC muscles than with the BS muscles. Anesthesia of IC muscles with lidocaine significantly reduced the CCP pressures and the dogs with low pressures were unable to copulate because of insufficient erection for intromission, which indicated that the IC muscles were the source of energy for the high CCP pressure. The mean peak CSP and bulbus glandis pressures during the intromission phase of coitus were 579 and 1280 mmHg, respectively. The contractile activity of the BS muscles was in phase with the CSP pressure peaks. Anesthesia of BS muscles with lidocaine reduced the peak CSP and bulbus glandis pressures during attempted coitus. The mean rupture pressure of the CCP was 86,615 mmHg.

Demeter on a Knossian ring-inscription

In a recent issue of this Journal (XCV, 1975, pp. 231–2), R. F. Willetts reviews the excellent publication of J. N. Coldstream, Knossos, the Sanctuary of Demeter (BSA, Suppl. Pap. 8, 1973). He draws attention to a boustrophedon inscription on a silver ring bezel, which he transcribes, after Coldstream:The reading seems to support Willetts' own views on the cult of Demeter as a Mother-Goddess in Crete.May I express some doubts about the actual reading of the dedication? I recently had the opportunity of examining the Knossos ring in the Heraklion Museum, by courtesy of the Director, Dr Alexiou, and of his Assistant, A. Lebesi. Magnifying techniques and contrasted lighting were available in the now well-equipped laboratory of the Museum. It appears that the lettering of the inscription is not exactly what Coldstream believed, although his photograph and facsimile are fairly accurate. First, the supposed digamma is a true alpha, with parallel strokes, as often occurs on archaic stones: the figure is quite similar to the other alphas of the text if you read it in the proper sense, i.e. as the first letter of the second direct line. Secondly, the last sigma of the retrograde line, with its two short angular strokes at sharp angles at each end of the hasta, seems most unlikely. There is actually a kind of cross-hatching on the surface, which is rather deceiving, but upon it you can distinguish the three bars of a delta, a very clear, although small and slightly debased one. The hasta forms one of these bars, and one other is the upper stroke of the so-called sigma.

Construction of Welded ‘Wet Loop’ Thermocouple Psychrometer Junctions1

AbstractThe construction and performance of a welded wire, wet loop (Richards') thermocouple psychrometer measuring junction are described. This junction is simpler to construct, not subject to the incomplete wetting error probable with previous designs, and more sensitive and stable than the silver ring junctions.

A rediscovered medieval inscribed ring

The silver ring illustrated in pl. IIIg has had a somewhat chequered history over the past years. From some time before 1911, when it was first published, until 1930 the ring was preserved in the Moyse's Hall Museum, Bury St Edmunds, Suffolk. In 1930 it was on display at the exhibition of English medieval art at the Victoria and Albert Museum in London. It subsequently disappeared from public view. In 1969 the Hon. Robert Erskine presented it to the Moyse's Hall Museum where it remains, acquisition number K. 132.

VII.—The Medieval Jewellery from the Fishpool, Nottinghamshire, Hoard

Hoards of coins that include jewellery are uncommon in the middle ages. In England up to 1966 there were only three such hoards known. These are the twelfth-century hoard from Lark Hill, Worcester, which contained six rings; the hoard from Coventry of c. 1290–8 containing two silver ring brooches; and the Thame hoard deposited after 1457 and containing five rings. In 1966 the discovery of a hoard of gold coins and jewellery at Fishpool, Nottinghamshire, added a fourth hoard to this sequence.

An Automatic Multichannel Thermocouple Psychrometer Based on an Operational Amplifier

Thermocouple psychrometers are used to measure the water potential of plant tissues and soils and the osmotic potential of solutions. The methods of using them have been described in detail by Barrs (1968). In the thermocouples developed by Richards & Ogata (1958) a small silver ring forms the junction of the couple and retains a drop of water. The thermocouple junction is then a permanent wet junction giving 'wet bulb' temperature. Alternatively Spanner (1951) cooled the thermocouple junction by passing a small electric current through it, condensing a drop of water. The 'wet bulb' temperature was measured after the cooling current was stopped. Systems have been made which scan several thermocouples automatically and record the output. They differ principally in the choice of amplifier. Rowse & Monteith (1969) used a galvanometer to amplify the signal for thermocouples of the design described by Spanner, digitized the amplified signal with an interference pattern and recorded on punched tape. The method demands considerable technical resources and the amplifier is bulky and sensitive to vibration. Also, only a fraction of the signal is recorded during evaporation of the drop, which may be unsatisfactory when the drop evaporates rapidly at low water potentials. Barrs (1969) used commercially obtainable components. A pulse generator activated a rotary multichannel switch, the signal was amplified using a microvolt amplifier and the output recorded on a strip chart recorder. This method can only be used with droplet thermocouples, the amplifier is expensive and the length of reading limited to 60 seconds by the pulse generator. The instrument described below can be used for both types of thermocouple; the length of the reading period is adjustable over a wide range, the amplifier is compact and inexpensive and gives estimates of water potential of + 0-2 bars. An operational amplifier was used because it is inexpensive and easily obtainable. The output is recorded on a strip chart, but could be digitized if required.

Physiological parameters of growth in Saprolegnia parasitica Coker.

Persistent bacteria were separated fromS. parasitica by means of the oligodynamic effect of a silver ring in a modification ofRaper's technique.

Calcium carbonate deposition on intrauterine contraceptive devices

IUDs worn for periods of from 3 months to 15 years by 75 Chinese women were removed for study. These included plastic IUDs Lippes loops and metallic rings: gold-plated silver Ota ring gold-plated sun-platinum ring and 18 carat gold ring. After water rinsing and drying IUDs were examined by eye and microscope. 4 months after insertion 2 spots of deposition appeared on the plastic IUD. The plastic devices had easily observed deposits beginning at 1 year and by 3 years a large part of the surface was covered. The silver ring had easily observed deposits at 6 years. The sun-platinum ring had scanty deposits at 7 years. The gold ring had scanty deposits at 10 and 15 years. The degrees of deposits on the plastic IUD were parallel to years of uterus placement. Under microscope the deposits appeared as calcium carbonate. This study suggests replacement times for various IUD devices and may explain formation of lithokelphos or lithopedion in the uterus.