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Biomedical subjects

R G Wheeler

Publications and source records attributed to R G Wheeler.

At least 19 recordsLinked to original sources
PubMed1987

Efficacy of two insertions of 100-minute releasing quinacrine hydrochloride pellets for non-surgical female sterilization.

Extensive research has been undertaken to develop a simple method of non-surgical female sterilization. Zipper and associates identified quinacrine hydrochloride as a drug likely to produce tubal occlusion when placed into the uterus. Zipper's early work with a solution of quinacrine led to the development of quinacrine pellets, a delivery system that was designed to bring the quinacrine into prolonged contact with the tubal ostia through extended uterine retention. Three transcervical uterine insertions of 10-minute releasing quinacrine hydrochloride pellets performed at monthly intervals have produced a 12-month pregnancy rate of 3.3 per 100 women. The ultimate goal is to develop an effective, single insertion procedure, but the performance of the quinacrine pellets in occluding tubes has necessitated more than one insertion. FHI developed a 100-minute extended release pellet system with the expectation that more prolonged drug exposure would produce a higher rate of tubal closure. A study of the 100-minute releasing pellet system has been conducted in Santiago, Chile. Two monthly insertions in 112 women has resulted in a 12-month pregnancy rate of 2.0 per 100 women. Postprocedure problems occurring within the first year were reported by 13% of the women; most were minor and transitory.

Adult↗
PubMed1987

Use of echosonography to monitor uterine placement of intrauterine devices after immediate postpartum insertions.

A study designed to monitor uterine placement of IUDs inserted immediately postpartum using echosonography was conducted at the Hospital de Gineco Obstetricia No. 23, "Dr. Ignacio Morones Prieto" in Monterrey, Mexico. TCu220 and Delta T IUDs were randomly assigned to, and inserted in women immediately following a normal vaginal delivery. Ultrasound examinations were to be performed within 60 min postinsertion, at 24 h postinsertion and at 1- and 3-month follow-up visits. There were no differences in the expulsion rates of the two device groups. Data are presented on the readings taken at the ultrasound examinations of the distance between the fundus and the upper part of the stem of the T. These differences differed significantly between the two device groups at the first ultrasound reading only (P less than or equal to 0.01). No relationship was found between the incidence of expulsion and the distance between the IUD and the fundus at any of the readings.

Female↗
PubMed1985

Non-surgical tubal occlusion.

Out of 151 women provided with chemical female sterilization with 3 insertions of 250 mg of quinacrine spaced 1 month apart, there were 7 pregnancies in 3 years. If these pregnancies were a result of failure to occlude the entrance to 1 or both fallopian tubes, birth events should decrease exponentially with time. Unexpectedly, the low failure rate has not decreased significantly over the 3-year observation period.

Acridines↗
PubMed1984

Postpartum insertion of modified intrauterine devices.

The immediate postpartum insertion of standard intrauterine devices (IUDs) and those specially modified for postpartum use was evaluated in a multicenter clinical trial. The immediate postpartum insertion of IUDs was not associated with any increased risk of perforation or infection, although expulsion rates were higher than with interval insertions. The expulsion rate varied widely between centers using similar devices, suggesting that training in insertion is essential. Postpartum IUD insertions can be a practical contraceptive option for patients and providers of medical services.

Adult↗
PubMed1983

Propranolol as a novel, effective spermicide: preliminary findings.

The efficacy and tolerability of 80 mg propranolol tablets as a vaginal contraceptive were studied in 198 fertile women for 11 months. The calculated one year life table pregnancy rate was 3.4/100 women and the Pearl index was 3.9/100 women years. No major adverse effects were encountered. The findings suggested that propranolol is an effective vaginal contraceptive whose failure rate compares favourably with that of other methods of contraception. Further study of propranolol and similar compounds is warranted.

Adolescent↗
PubMed1983

Properties and safety of cervical dilators.

Characteristics of cervical dilation produced by the new osmotic dilator, laminaria, and rigid (metal or plastic) dilators were compared. The osmotic dilator (Lamicel) is an open-porosity polyvinyl alcohol sponge loaded with magnesium sulfate and compressed into a rod. Pressures exerted by the Lamicel and laminaria tents were measured by placing them in a short elastic collar to simulate the cervical canal and allowing them to swell in water. At maximum dilation of the collar, the laminaria exerted 190 kPa (kPa = kilopascals; 6.895 kPa = 1 pound force/square inch), and the osmotic dilator, 14 kPa. The pressure that may be applied to the cervical canal with rigid dilators may be as much as 700 kPa. Because the Lamicel dilates the cervix passively and is as effective as laminaria, it appears to be the safest method of cervical dilation.

Cervix Uteri↗
PubMed1982

Effect of topically applied adrenergic blockers on fertility.

The contraceptive properties of two adrenergically active drugs, propranolol and reserpine, were measured in vivo and in vitro. Propranolol became effective as a spermicide for human sperm at a concentration of about 2 x 10(-3) M and for rat sperm at 2 x 10(-2) M. Reserpine was also more effective on human than rat sperm and about 20 times less effective than propranolol. Both propranolol and reserpine prevented implantation when instilled into the uteri of rats. The anti-implantation effect persisted for up to 5 days after instillation of propranolol. When freely breeding rats eventually became pregnant after daily vaginal instillation of propranolol, the number of uterine implantations decreased as the concentration of vaginally instilled propranolol increased. The implantations tended to be toward the fundal end of the uteri, away from the source of propranolol, thus indicating a topical rather than a systemic anti-implantation effect.

Animals↗
PubMed1977

Electrochemical effects of metals on IUDs.

Electrochemical effects within the uterus are being studied, particularly as they pertain to IUDs made in total or in part of metals. The intrauterine potential as measured with either metal or nonpolarizable salt electrodes is positive at the fundal with respect to the cervical end of the uterus. Placement of dissimilar metal electrodes within the uterus will induce voltage gradients that are roughly predictable from their cell potential in blood as an electrolyte. When copper and zinc electrodes are placed at opposite ends of the uterus, they induce voltage gradients that are typically greater than 100 mv per cm. External copper and zinc wires connected at one end, and with the other ends in contact with various positions on the skin of rats, were found to influence potential gradients within the uterus. When a length of zinc wire was wound around the upper portion of the stem of a small Cu-7 200 IUD, it took about 1 year from insertion for the zinc to disappear. When the zinc wire was wound around the lower portion of the stem, it disappeared in 1 month. The zinc reduced intrauterine corrosion of the copper and it was more effective at reducing copper corrosion when in the lower stem position.

Action Potentials↗
PubMed1975

Uterine copper distribution in monkeys implanted with copper-carrying intrauterine devices.

Chemical and histochemical analyses were carried out on uteri of four monkeys in which plastic IUDs or Cu-IUDs had been implanted for 36 to 43 days. The mean uterine copper content of the plastic-treated animals was 1.1 mug/gm (mean of two), while this value for the Cu-IUD treated monkeys was 1.7 mug/gm. The copper was distributed primarily in the cyclically renewed regions of the endometrium: the luminal fluid, endometrial surface, and superficial lamina propria. The element was localized and was not uniformly distributed in these regions. Copper analyses of plasma, liver, and kidney showed no differences between these two groups. Histopathologic evaluation revealed some areas of edema and increased numbers of neutrophils in plastic-IUD-treated animals. In the Cu-IUD-implanted monkeys, similar changes were observed as was a flattening of the surface epithelium. The endometrium had a loose areolar appearance. The copper elution rate was about 90 mug/day, about twice that observed in women using Cu-IUDs.

Animals↗