Ring Insertion Research Articles

Vaginal epithelial surface appearances in women using vaginal rings for contraception

Vaginal inspections using colposcopy before insertion of contraceptive vaginal rings and at 2-month intervals during ring use were conducted on 169 users of four different formulations. The rings studied released Nestorone® alone (50, 75, 100 μg daily over 6 months); ethinyl estradiol: Nestorone (30:100 and 15:150 μg daily over 6 months); ethinylestradiol:norethindrone acetate (20:1000 and 15:1000 μg daily over 4 months); and ethinyl estradiol:norethindrone acetate (20:1000 μg daily over 12 months). A total of 88 altered or atypical conditions of the vaginal surface appearance were recorded in 507 inspections (17.4% of inspections). Many of these atypical appearances were quite subtle. The incidence was significantly higher (p <0.01) than in the single pretreatment examinations (11 in 158 inspections; 7.0%), but closely matched that of a “control group” of sexually active women who were the subject of an earlier study by the same investigators. In that study, the incidence was 18% (57 atypical conditions in 317 inspections). In all, 83% of atypical conditions identified in the vagina during ring use had disappeared by the next scheduled colposcopy despite continued ring use. Findings of potential significance were conservatively defined as all ulcerations, those abrasions and ecchymoses that were >0.5 cm in any direction, and fields of five or more petechiae. Findings fitting those criteria comprised 30% of atypical conditions in ring users, 33% in the control group, and 27% pretreatment. The corresponding incidence as a percentage of inspections were 5.3%, 6.0%, and 2.5% in the ring users, control groups, and pretreatment groups, respectively. These differences were not statistically significant. The findings suggest that the vaginal rings included in the studies contributed little, if at all, to clinically significant lesions or to total lesion incidence. Further definition would require a larger and longer-term study with matched controls.

Emissions and efficiency of a prototype natural gas‐fired domestic cooktop burner with insert

This paper reports on the performance of a prototype natural gas‐fired cooktop burner which was developed for lower NO2 emissions and improved thermal efficiency. A circular ring insert was part of the prototype burner. It was made from 6 mm stainless steel rod and placed at the side of the burner slightly below the ports. The prototype burner had a 42% lower NO2 emission per unit useful energy compared to a commercially available burner at 3.3 kW. The relative improvement in thermal efficiency was 19%. The prototype burner was tested over the full range of thermal input, from 3.3 kW down to 0.66 kW. The insert did not cause any problem for emissions or efficiency at any thermal input within the range, provided it was appropriately located relative to the burner ports. As the burner was turned down, the NO2 emission decreased and thermal efficiency increased, as normally observed with gas cooktop burners.

High Resolution Electron Microscopy (HREM) Study of Chemically Vapor Deposited Polycrystalline Si1-xGex Thin Films

ABSTRACTThe microstructure of polysilicon and Si0.69Ge0.31 thin films, grown by chemical-vapordeposition (CVD) on oxidized silicon wafers covered with a very thin polysilicon seed layer, was investigated using high-resolution electron microscopy (HREM). The plan-view HREM images showed that polysilicon films contained less substructure inside grains and had fewer multiple twins and more extended twin bands than Si0.69Ge0.31. On the other hand, only SiGe contained multiple twins with five-fold symmetry. The atomic model of the second-order symmetric twin boundary proposed for Si and based on the insertion of five-member and seven-membered rings was found to describe the atomic structures of second-order symmetric twin boundaries in Si0.69Ge0.31 as well. Within the accuracy of HREM, the repeat unit of the boundary was the same in Si0.69Ge0.31 and Si.

Self-excitation and operational characteristics of the crossed-field secondary emission electron source

We have investigated the crossed-field secondary emission (CFSE) electron source which is of a magnetron type with smooth cylindrical electrodes and axial applied magnetic field. It initiates at the negative slope d|U|/dt&amp;lt;0 of the high voltage pulse U∼10–40 kV, but further current production is maintained by a self-sustained secondary electron emission regardless to the voltage pulse shape. The output electron beam is tubular with a thin ∼1 mm wall. This article is concerned mainly with the identification of the mechanisms governing the excitation and generation of the electron beam and with the determination of the principles upon which the “optimal” CFSE electron source should be designed. We have demonstrated that the CFSE diode starts operation in a self-excitation regime (i.e., without application of the primary current) provided there is a partial trapping of the multiplying electrons inside the diode boundaries. The required axial decelerating force can be established with the use of either axial electric or nonuniform magnetic fields. Amongst all of the practical methods tested (shifting of the anode with respect to the cathode, double diode, diodes with ferromagnetic parts, use of the nonuniform external magnetic field), the diode with a ferromagnetic ring insert inside the cathode cylinder has been shown to be the most successful. It has generated an ∼240 A electron beam with a perveance of ∼85 μA/V3/2. The operating range of the CFSE diode is limited by both low and high magnetic fields. The lower limit arises from a necessity to comply with a Hull cutoff condition. The upper limit is determined by the time required for development of an electron avalanche. A secondary electron emission mechanism of current production in the CFSE diode allows the diode to operate in an oscillating regime when the applied magnetic field is higher but close to the Hull cutoff value. It has thus been possible to generate 100% density modulated electron beams at a modulation frequency of ∼107 Hz in our present experiments with the possibility of further increases up to ∼108 Hz. A geometrical scaling law for the CFSE diodes has been deduced empirically. It states that the perveance of the output electron beam is proportional to the geometrical factor X=(Dk/de)(Ld/de−0.8), where Dk is the cathode diameter, de is an effective diode gap, and Ld is the diode length. The scaling law provides a tool for designing the CFSE diodes and predicting the ultimate beam currents. For a practical size of device, this electron current could be as high as ∼1 kA.

Efficacy, bleeding patterns, and side effects of a 1-year contraceptive vaginal ring

A combined contraceptive vaginal ring designed to last 12 months was tested at three clinic sites. This ring released approximately 1 mg of norethindrone acetate (NET-Ac) and 20 μg of ethinyl estradiol (EE) daily. A total of 60 women were enrolled to use the ring in a schedule of 3 weeks in/1 week out. Serum norethindrone (NET) and ethinyl estradiol (EE) levels were assayed twice weekly in cycles 6, 9, and 13. Mean NET concentrations between cycles 6 and 9 were relatively stable between 13 and 19 nmol/L but showed a 10%–21% decrease in all centers between cycles 9 and 13. Mean EE concentrations ranged from 75 to 103 pmol/L, but did not have the same decrease as NET between cycles 9 and 13. Cycles with progesterone peaks (>9.6 nmol/L) compatible with some luteal activity occurred in 4% of cycles sampled in Sydney, 3% in Santo Domingo, and 26% in Los Angeles. Half of these cycles exhibited at least one progesterone value >32 nmol/L with three of 18 occurring in noncompliant cycles. Heavier body weight was associated with increased probability of luteal activity. Based on serum estradiol peaks >400 pmol/L, eight of 81 cycles appeared to have marked follicular activity with no luteal activity. No pregnancies occurred. Nausea was reported by about half the subjects in approximately 10% of the visits (mainly in the first 1–2 days in the first cycle immediately after ring insertion). Vomiting was reported by 20% of subjects early in the first cycle only. Headache was reported on occasion by nearly 50% of the women, but the relationship to ring use was uncertain. Vaginal discharge was reported by 17 women (82% of these were from one clinic). Of 60 women, 14 discontinued before completing the study, but only two discontinuations were for medical reasons. Small but statistically significant changes occurred in lipid levels in two of the three centers. All changes remained within normal limits and were similar to those seen with many oral contraceptives It appears that this ring may perform slightly differently in different populations, but is a highly satisfactory method of contraception for many women. Minor modifications in design could provide higher levels of steroid release and in the later months of the ring life span would assure continuing high levels of contraceptive protection for heavier women.

Is a prosthetic ring required for mitral repair of mitral insufficiency due to posterior leaflet prolapse? Long-term results in 96 patients submitted to repair with no ring.

It is a common statement that every mitral repair should be stabilized by some type of prosthetic mitral ring. In the very specific situation of isolated prolapse of the posterior leaflet (PPL), this statement may be enhanced by the possible anatomically discontinuity of the mitral annulus. This article concerns 96 patients with 'isolated' PPL (IPPL) who were operated upon without ring insertion. Long-term follow-up was obtained in order to ascertain the survival, stability of the repair and the need for reoperation, thus justifying or not the lack of use of a ring. A total of 96 patients, 70 male and 26 female, underwent mitral repair for mitral insufficiency (MI) almost exclusively caused by PPL. Age ranged from 33 to 81 years (mean 60.7+/-11.3). All underwent quadrangular resection of the prolapsed portion and plication of the annulus. In 69 cases local stabilization was achieved by four U stitches, two on each side of the plication, passed through and sutured on some flexible material, 2-3 cm in length. Twenty seven patients had no such local reinforcement. There was one case of early death (1%) caused by refractory hypoxemia in a patient with long lasting pre-operative pulmonary edema. Two patients were lost for follow-up after 2 months. Follow-up was from 0.2 to 14.7 years (mean 4.5), for a total of 422.7 patient-years. There were four late deaths at a mean of 6-year follow-up (0.9-10 years). Actuarial survival was 95.5 and 90.5% at 5 and 8 years, respectively. Event-free for recurrence of significant mitral insufficiency (MI) was 96 and 92% at 5 and 8 years. Event-free of thromboembolic or hemorrhagic events was 84.3 and 72.3% at 5 and 8 years. Event-free from reoperation was 97.8 and 94% at 5 and 8 years. One can conclude that (a) IPPL repair without insertion of a ring is safe and long-lasting (b) the incidence of late death, recurrence of MI, thromboembolic/hemorrhagic events, need for reoperation, is not higher in this subset of patients than in conventional repair (c) such repair might work better and for a longer time, as reaction and sclerosis resulting from ring insertion are avoided (d) minor advantages could be due to an easier surgical procedure, especially through a minimally invasive approach.

Equator ring efficacy in maintaining capsular bag integrity and transparency after cataract removal in monkey eyes.

The purpose of the study was to evaluate the efficacy of the equator ring in maintaining capsular bag integrity at the equator and transparency of the posterior capsule after cataract surgery. using cynomolgus monkeys. After lens removal using an infusion-aspiration method, a flexible silicone ring with a groove on its inner surface was inserted in the bag through a window made by continuous circular capsulorhexis in six eyes. Of these, four monkey eyes underwent posterior chamber intraocular lens (IOL) implantation and two monkey eyes did not receive IOLs. Lensectomy without ring insertion was performed as a control in the six fellow eyes. Of these, four eyes received an IOL and two did not. The eyes were followed for an average of 5.9 +/- 1.1 months before enucleation. The effects were evaluated by stereo and light microscopy. The ring effectively maintained the circular contour of the capsular bag (ratio of the short and long axes, 0.97 +/- 0.01) and posterior capsule transparency (P = 0.017). This study demonstrated that the equator ring is a promising device for maintaining capsular bag integrity and minimizing posterior capsule opacification after cataract surgery.

Organogold(III) metallacyclic chemistry. Part 2. Synthesis and characterisation of the first gold(III) ureylene complexes. Crystal structures of [{C 6H 3(CH 2[formula omitted]R}] (R=Ph and C(O)Me

The reactions of the cyclometallated gold complex [A u{C 6 H 3( CH 2 N Me 2)-2-(OMe)-5}Cl 2] 3a with N, N'-diphenylurea or N, N'-diacetylurea using an excess of silver(I) oxide in refluxing dichloromethane gave the aura-ureylene complexes [{C 6H 3(CH 2 NMe 2) −2−(OMe)−5}A u{NRC(O)N R}] R=Ph 6a and R=Ac [Ac=C(O)Me] 6b respectively, containing the A u–N–C(O)–N four-membered ring. This ring system has not been reported for gold previously, but is known for other metals e.g. Pt, Pd, Rh, Ir, Ru, Os and Re. The complex 6a was also successfully synthesised by reaction of 3a, N, N'-diphenylurea and sodium hydride in THF at room temperature. The complexes have been fully characterised by 1H- and 13C-NMR and IR spectroscopies, electrospray mass spectrometry, and single crystal X-ray structures are reported for both complexes. The latter shows the aura-ureylene rings of both complexes are planar. Reaction of 6a with phenyl isocyanate gave the expected six-membered ring insertion product [{C 6H 3(CH2 NMe 2) −2−(OMe)−5}A u{NPhC(O)NPhC(O)NPh }] 11, although dimethyl acetylenedicarboxylate proved unreactive. Pure samples of 11 readily deinsert phenyl isocyanate in solution, to regenerate 6a. This is also clearly observed in electrospray mass spectrometry studies. The biological properties of 6b have been assessed and the compound possesses high cytotoxicity and moderate antitumour activity.

Solution structure of the aminofluorene [AF]-external conformer of the anti-[AF]-C8-dG adduct opposite dC in a DNA duplex.

The Escherichia coli genome contains a C-G1-G2-C-G3-C-C NarI hot spot sequence for -2 deletion mutations at G3 by aromatic amine carcinogens 2-acetylaminofluorene (AAF) and 2-aminofluorene (AF) that form covalent adducts at the C8-position of the guanine ring. Each of the three guanines are positioned in different sequence contexts (C-G1-G, G-G2-C, and C-G3-C) which provides an opportunity to investigate the potential sequence dependent interconversion between AF-intercalated and AF-external conformers of the [AF]dG adduct positioned opposite dC within the NarI sequence at the duplex level. We have prepared and purified DNA duplexes containing the [AF]dG adduct positioned in C-[AF]G-G, G-[AF]G-C, and C-[AF]G-C NarI sequence contexts and observe the ratio of AF-intercalated to AF-external conformers to be 30:70, 10:90, and 50:50, respectively. We have applied a combined NMR-molecular mechanics approach to define the structure of the AF-external conformer in the G-[AF]G-C NarI sequence context where it is the predominant conformation (90%) in solution. The modified guanine of the [AF]dG adduct aligns through Watson-Crick pairing with its partner cytosine and is stacked into the helix between flanking Watson-Crick dG.dC base pairs. The AF-external conformer with its anti-[AF]dG residue causes minimal perturbations in the DNA duplex at and adjacent to the lesion site with the covalently linked fluorenyl ring readily accommodated in the major groove and tilted toward the 5'-end of the modified strand of the helix. This paper on the structure of the AF-external conformer with an anti-[AF]dG adduct together with the preceding paper in this issue on the structure of the AF-intercalated conformer with a syn-[AF]dG adduct defines for the first time the capacity of the mutagenic [AF]dG lesion to adopt interconverting syn and antialignments with the equilibrium shifting between the conformers depending on nearest neighbor and next-nearest neighbor sequences. Perhaps, recognition of the [AF]dG lesion by the repair machinery would be able to discriminate between the AF-intercalated conformer with its base displacement-fluorenyl ring insertion perturbation of the helix and the AF-external conformer where the DNA helix is essentially unperturbed at the lesion site and the fluorenyl ring is positioned with directionality in the major groove.

A Generalized Solution to Infiltration from Single‐Ring Infiltrometers by Scaling

AbstractWater infiltration into soil from a ring infiltrometer is an important issue for many scientific and engineering problems. Due to the complexity of the three‐dimensional water flow, no generalized solutions are available to describe the infiltration process from a finite ponding source. This study applied a scaling technique to three‐dimensional axisymmetric infiltration from a single‐ring infiltrometer to obtain a generalized infiltration solution and evaluated the effects of soil conditions and ring geometry on the scaled infiltration curves. A numerical model based on Richards' equation in the cylindrical coordinates was developed to simulate infiltration processes for three representative soils. By properly choosing length‐ and time‐scale factors, the infiltration curves of the three test soils representing different hydraulic properties were successfully scaled to essentially a single dimensionless infiltration curve. Tests showed that the dimensionless infiltration curve was not very sensitive to applied ponding head, ring diameter, ring insertion depth, and initial soil conditions. Finally a dimensionless infiltration equation in the form of i* = a + blt*0.5 was developed. The example showed that the generalized infiltration equation can predict the infiltration curve simulated by Richards' equation very well.

Signal processing, data acquisition, and initial commissioning results of the APS storage ring vertical beam missteering wire monitor

Two wire monitors have been developed and installed in the Advanced Photon Source (APS) storage ring insertion device (ID) front ends to directly detect synchrotron radiation exiting the storage ring vacuum chamber that is missteered by ±5 mm. Each wire monitor employs four in-vacuum tungsten wires positioned above and below the normal x-ray orbit. The temperature change of the wire under x-ray irradiation causes a resistance change that is detected by a local high-sensitivity low-noise signal processing electronics unit with four independent channels. The four outputs of the local unit are linked to a central VME wire resistance measurement and interlock module via 4–20 mA current loops. The central VME module can accept inputs from up to eight wire monitors and has a heartbeat that feeds a MPS summation module. In this paper, an overview of the wire monitor signal processing and data acquisition system design is presented together with recent commissioning results.

Some reactions of 2,4-diphosphaplatinocycles and the crystal structures of

The structure of the ring insertion product 1b obtained from the reaction of [Pt(dppm)(CH 2Cl 2] (dppm = Ph 2PCH 2PPh 2) with triphenylphosphine has been confirmed by X-ray crystallography of the hexafluorophosphate salt. The bis-chelate complex ▪ ( IIIa) has been isolated from the reaction of [Pt(dppm)(CH 2Cl 2] ( II) with diphenylphosphine in dichloromethane. Iodination of Ib leads to selective cleavage of the chloromethyl group, and subsequent iodide abstraction with silver ion gives a solvated cation ( V). The structures of the hexafluorophosphate salts of the bis-chelate IIIb and of the solvated cation V have been determined by X-ray diffraction.

ChemInform Abstract: Tandem Ring Expansion and Insertion Reaction of Alkenic Cyclobutanols Mediated by Palladium. A Novel Approach to Bicyclo(4.3.0)nonane Systems.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: A Novel Access to Hydrindan Derivatives by Palladium Mediated Tandem Ring Expansion and Insertion Reaction of Alkenic Cyclobutanols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Pharmacokinetic and pharmacodynamic effects of vaginal rings releasing levonorgestrel at a rate of 27 μg/24 hours: A pilot study

The pharmacokinetic and pharmacodynamic effects of vaginal rings releasing levonorgestrel (L-NOG) at an initial rate of 27 μg/24 h were studied in a group of 12 normally menstruating women during 90 days of continuous use (i.e., during three 30-day treatment segments). Blood samples were drawn immediately before insertion, 15 and 30 min, as well as 1, 2, 4, 8, 12 and 24 h after insertion of the rings, and thereafter three times weekly throughout the study for the analysis of L-NOG, estradiol, progesterone and sex hormone-binding globulin (SHBG). Endometrial biopsies were obtained for a morpho-metric analysis in a pre-treatment (control) cycle and in the 6th and 10th weeks of treatment. The peak of average L-NOG levels was reached within two hours after the insertion of rings. Until 24 h after insertion, the levels did not change significantly. Thereafter, a decrease at a rate of 0.2% per day was initiated. The L-NOG and SHBG levels were highly correlated. This was seen for both the pre-treatment SHBG vs L-NOG ( r = 0.96) and the treatment SHBG vs L-NOG levels ( r = 0.92). There was a significant ( p < 0.001) decrease of SHBG levels due to treatment. During the total of 36 treatment segments, a normal ovarian function was seen in 47% of the segments. The women were anovulatory and had an inadequate lutal function in 28% and 25% of segments, respectively. No correlation between the L-NOG levels and ovarian reaction to treatment was found. The use of L-NOG induced significant changes in the endometrium; the number of glands/mm 2 decreased after 6 ( p < 0.02) and 10 weeks of use ( p<0.01). Also, the diameter of glands and the occurrence of vacuolated cells decreased significantly ( p < 0.02 and p < 0.005, respectively). None of the endometrial parameters or dating was correlated with the ovarian reaction to treatment, indicating independent endometrial effects of L-NOG.

Tandem ring expansion and insertion reaction of alkenic cyclobutanols mediated by palladium—A novel approach to bicyclo[4.3.O]nonane systems

A new method for the synthesis of hydrindans was developed by the palladium mediated tandem ring expansion and insertion reaction of alkenic cyclobutanol 5 to give the hydrindan 17 as a key step.

A Novel Access to Hydrindan Derivatives by Palladium Mediated Tandem Ring Expansion and Insertion Reaction of Alkenic Cyclobutanols

A Novel Access to Hydrindan Derivatives by Palladium Mediated Tandem Ring Expansion and Insertion Reaction of Alkenic Cyclobutanols

The electronic spectrum of fullerenes from the Dirac equation

The electronic spectrum of sheets of graphite (plane honeycomb lattice) folded into regular polyhedra is studied. A continuum limit valid for sufficiently large molecules and based on the tight-binding approximation is derived. It is found that a Dirac equation describes the flat graphite lattice. Curving the lattice by insertion of odd-numbered rings can be mimicked by coupling effective gauge fields. In particular the C 60 and related molecules are well described by the Dirac equation on the surface of a sphere coupled to a color monopole sitting at its center.

Biosynthesis of vitamin B 12: Discovery of the enzymes for oxidative ring contraction and insertion of the fourth methyl group

In the vitamin B 12 biosynthetic pathway the enzymes responsible for the conversion of precorrin-3 to precorrin-4 have been identified as the gene products of cobG and cobJ from Pseudomonas denitrificans. CobG catalyzes the oxidation of precorrin-3 to precorrin-3x (a hydroxy lactone) whereas CobJ is a SAM-dependent C-17 methyl transferase and is necessary for ring contraction. A mechanism for ring contraction is proposed.

ChemInform Abstract: Ring Insertion Reactions of Silaaziridines with Aldehydes and Isocyanates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.