Biomedical subjects
S W Cohen
Publications and source records attributed to S W Cohen.
Variability of midcycle estradiol positive feedback: evidence for unique pituitary responses in individual women.
In women the preovulatory estradiol (E2) level must reach a peak concentration and dose (strength and duration) to initiate the LH surge. The variability of the surge-initiating serum E2 level in individual women from cycle to cycle, however, has not been studied. Accordingly, we studied 24 normally ovulating women longitudinally during a total of 221 menstrual cycles (range, 4-17 cycles/woman). In those women we measured periovulatory serum E2 and LH concentrations daily from 3 days before the LH peak to the day after the LH peak. The mean peak E2 concentration was 343 pg/mL, and the mean E2 dose (concentration X time) was 979 pg/mL. When the values in individual women were compared between women by components of variance analysis of variance, the differences were significant (concentration, P less than 0.01; dose, P less than 0.005), indicating that individual women have discrete and characteristic responses to E2 positive feedback. When E2 peaks and doses from initial cycles were compared with subsequent cycles by regression analysis, there were strong positive correlations (peak: r = 0.47; P less than 0.001; dose: r = 0.60; P less than 0.001). Of the total group variance in mean E2 peak and mean dose, 67% of the peak and 54% of the dose variance resulted from an individual woman's cycle to cycle variability, while 33% of the peak and 46% of the dose variance was attributable to differences among the women's responses to positive feedback. We conclude that individual women have characteristic and predictable periovulatory E2 production, leading to a LH surge which is maintained from cycle to cycle; and approximately two thirds of the total variance in mean peak E2 concentration (67%) and approximately half the variance in mean dose (54%) are the result of cycle to cycle biological variability around this characteristic periovulatory pattern of E2 production.
Polysiloxane vaginal rings and cylinders for physiologic endometrial priming in functionally agonadal women.
17 beta-estradiol (E2)-and/or crystalline progesterone (P)-impregnated polysiloxane vaginal rings and cylinders were tested as a system for endometrial priming in functionally agonadal women awaiting donor embryo transfer. Endometrial tissue was obtained by a transcervical biopsy procedure on simulated cycle day 26. The adequacy of the replacement regimen was judged by endometrial histologic dating, scanning electron micrographs, receptor content, and circulating E2 and P serum concentrations. Endometrial dating was consistent with cycle day 26. Electron micrographs showed normal surface characteristics. E2 and P receptor concentrations were within the normal range. Serum E2 levels were midfollicular, 105 +/- 12.8 pg/ml (mean +/- SEM), and midcycle, 254 +/- 28.6 pg/ml. P levels during the simulated follicular phase were undetectable (less than 0.2 ng/ml) but rose to a mean peak level of 17.3 +/- 1.8 ng/ml. The steroid-impregnated polysiloxane vaginal ring and cylinder system provided continuous and sustained hormone release, morphologically and endocrinologically normal endometrium, serum levels of E2 and P within the normal range for the entire menstrual cycle, and a convenient and physiologic therapeutic alternative to oral, vaginal, or intramuscular steroid replacement.
Biologic and morphologic development of donated human ova recovered by nonsurgical uterine lavage.
Using uterine lavage performed 5 days after the luteinizing hormone peak, we collected 25 uterine ova from five fertile donors who had had a single, periovular artificial insemination. After examination, all recovered ova were transferred to recipient uteri and resulted in three intrauterine and one tubal pregnancy. Morphologic development ranged from degenerating single-cell ova to mature blastocysts. Ages of the ova at recovery ranged from 93.5 to 130.0 hours postovulation. Mean age of the five blastocysts, 109.1 hours, was not significantly different from the mean age of the 20 less mature ova, 108.1 hours. Neither the mean interval from insemination to recovery for blastocysts nor the mean interval from insemination to ovulation for blastocysts was significantly different from the mean intervals of the other ova. The five blastocysts resulted in intrauterine pregnancies in three recipients. There were no intrauterine pregnancies from the other 20 transfers (p less than 0.004). A transferred 12-cell ovum with degenerating blastomeres was associated with tubal pregnancy in the recipient. The large variability in the state of intrauterine ova observed in the relatively fixed postovulatory interval of this study appears to be due to differences in viability and maturation, not differences in ovum age. Maturational state of the ova at the time of transfer appears to be a significant determinant of the likelihood of ensuring pregnancy.
A pinhole plus occluder.
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Infrared viewer and image intensifier.
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Automated phakotomy and aspiration of soft congenital and traumatic cataracts.
The design and operation of an automated instrument for removal of a soft cataract through a small corneal incision has been described in a small series of young patients. The distinct advantages of the instrument and technique are the small single-entry corneal incision, the minimal manipulation on the part of the surgeon, the relative constancy of both the anatomical shape of the globe and of a predetermined intraocular pressure during the procedure, a decreased inflammatory response, and a rapid wound healing.
A fiber-optics cyclodialysis spatula.
A cyclodialysis spatula for glaucoma surgery with a fiber-optics bundle incorporated within its thickness is described. The instrument is used as is commonly done at present with the standard cyclodialysis spatula. In addition, the fiber-optics bundle delivers cold light to the tip of the spatula which is useful in helping the surgeon locate the spatula within the sclera and the anterior chamber.
Dacryoscopy.
A miniature caliber endoscope is described for introduction into the lacrimal excretory passages. Direct observation and diagnostic inspection of the contents and lining of the lacrimal sac and naso-lacrimal duct are possible with the instrument, and complement standard examination procedures of the lacrimal outflow system.
Choroidography and photography of the long ciliary nerve and artery.
A noninvasive technique that allows photography of the choroidal vasculature and the long ciliary nerve and artery is described. It does not make use of any injectable contrast material. A simple single lens reflex camera with its close-up lens, mounted on a stand, was used to take illustrative choroidograms.
Testing of Bell's phenomenon by transocular transcutaneous transillumination.
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Automated motorized penetrating keratoplasty.
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A fiber-optics pig-tail probe.
A pig-tail probe with a fiber-optics bundle incorporated within its thickness is described. The instrument is used as is commonly done at present with the standard pig-tail probe. In addition, the fiber-optics bundle delivers cold light to the tip of the probe which has been found very useful for locating the torn ends of a canaliculus, as well as delineating the anatomy of the lacrimal sac.
A fiberoptics ophthalmodynamometer.
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Biomicroscopical choroidoscopy (uveoscopy) and transillumination gonioscopy.
A fiber optic sleeve that fits over a Goldmann three-mirror lens, as well as an independent cable used in conjunction with the Goldmann lens, are described for transillumination biomicroscopical examination of the anterior chamber angle and the uvea. High-intensity retroillumination is provided to the anterior and posterior segments of the globe without production of heat to the eye. Present clinical uses as well as possible future research with the instruments are discussed.