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Biomedical subjects

R Angell

Publications and source records attributed to R Angell.

15 recordsLinked to original sources
PubMed1997

First-meiotic-division nondisjunction in human oocytes.

Reject oocytes from in vitro-fertilization patients are currently the only practical source of human oocyte material available for meiotic studies in women. Two hundred clearly analyzable second meiotic (MII) metaphase oocytes from 116 patients were examined for evidence of first meiotic (MI) division errors. The chromosome results, in which 67% of oocytes had a normal 23,X chromosome complement but none had an extra whole chromosome, cast doubt on the relevance, to human oocytes, of those theories of nondisjunction that propose that both chromosomes of the bivalent fail to disjoin at MI so that both move to one pole and result in an additional whole chromosome at MII metaphase. The only class of abnormality found in the MII oocytes had single chromatids (half-chromosomes) replacing whole chromosomes. Analysis of the chromosomally abnormal oocytes revealed an extremely close correlation with data on trisomies in spontaneous abortions, with respect to chromosome distribution, frequency, and maternal age, and indicated the likelihood of the chromatid abnormalities being the MI-division nondisjunction products that lead to trisomy formation after fertilization. The most likely derivation of the abnormalities is through a from of misdivision process usually associated with univalents, in which the centromeres divide precociously at MI, instead of MII, division. In the light of recent data that show that altered recombination patterns of the affected chromosomes are a key feature of most MI-division trisomies, the oocyte data imply that the vulnerable meiotic configurations arising from altered recombination patterns are processed as functional univalents in older women. Preliminary evidence from MI-metaphase oocytes supports this view.

Adult↗
PubMed1990

Treatment of Tourette's syndrome with transdermal clonidine: a pilot study.

Nine patients with mild Tourette's syndrome completed a cross-over, placebo-controlled study of clonidine administered transdermally. Although the subjects showed no improvement on objective measures of symptom severity, most subjects felt they had improved. Seven subjects chose to continue taking clonidine. Larger, blinded studies of transdermal clonidine are indicated.

Administration, Cutaneous↗
PubMed1989

A three-year follow-up of Cambodian young people traumatized as children.

Twenty-seven Cambodian young people, who were severely traumatized at ages 8 to 12, were followed up 3 years after an original study. A structured interview and self-rating scales showed that post-traumatic stress disorders (PTSD) were still highly prevalent (48%). Depression existed in 41%. Those with PTSD differed significantly from those without PTSD on the Global Adjustment Scale, the Social Adjustment Scale, the Beck Depression Inventory, and the Impact of Event Scale. Eight subjects had PTSD at both interviews, while 11 had none at either time. Eight showed a variable course. Avoidance behavior was highly prevalent, even among those without PTSD diagnosis. Although functioning relatively well, these youths continued to show symptoms related to their trauma of 8 to 12 years before.

Adolescent↗
PubMed1986

A comparison of fixed regimens for obtaining human cleaving oocytes for research purposes.

A fixed schedule for ovarian stimulation and follicular aspiration, previously used in our department for research purposes, was modified in an attempt to increase the recovery and cleavage rates of the oocytes. Three different clomiphene regimens were used to stimulate the ovaries of normal volunteer women requesting laparoscopic sterilization (50 mg and 150 mg daily for 5 days, and 50 mg daily for 10 days). Oocytes were recovered from 83% of the aspirated follicles, i.e. 1.6 oocytes/patient: 65% of the oocytes cleaved after in-vitro fertilization and, on average, 1.0 cleaving egg was obtained per patient. There were no differences in the recovery and cleavage rates between the three clomiphene regimens. It is concluded that a sufficient number of cleaving embryos for research purposes can be generated with the present fixed regimen, which offers little inconvenience to the volunteers as the day of egg recovery can be predicted some time in advance.

Adult↗
PubMed1985

Meiosis-inducing substances in human preovulatory follicular fluid related to time of follicle aspiration and to the potential of the oocyte to fertilize and cleave in vitro.

Meiosis-inducing substance (MIS) and steroid and gonadotropic hormones were investigated in 41 preovulatory follicular fluids (FFs) aspirated at either 0, 12, or 36 hours after human chorionic gonadotropin (hCG) administration in 25 women with clomiphene citrate-stimulated cycles. Twenty-one oocytes were recovered from these FFs and subjected to in vitro fertilization. MIS activity was present in 25 (61%) of the FFs. The frequency of MIS-active FFs increased from 11% (1 of 9) at 0 hours and 40% (2 of 5) at 12 hours to 81% (22 of 27) at 36 hours after hCG administration (P less than 0.001). The concentration of hormones in MIS-active FFs was not significantly different from that of MIS-inactive FFs. Twelve (86%) of 14 oocytes that fertilized and cleaved in vitro were recovered from MIS-active FFs. By contrast, all seven oocytes that remained unfertilized in vitro were recovered from MIS-inactive FFs. These findings support the notion that resumption of meiosis in the preovulatory oocyte is triggered by MIS in FF and suggest that follicular MIS production may be one of the factors that determines the success of in vitro fertilization and early embryonic development.

Androstenedione↗
PubMed1984

The recovery of pre-ovulatory oocytes using a fixed schedule of ovulation induction and follicle aspiration.

Thirty-two volunteer women, scheduled for laparoscopy, were subjected to a fixed regimen of ovulation induction and ovarian follicle aspiration, following manipulation of the previous menstrual cycle with oral contraceptive pills or norethisterone. This allowed the time of oocyte recovery to be planned several weeks in advance. The recovery rate of mature oocytes (loosely dispersed cumulus) in the patients who had their cycles adjusted with norethisterone was comparable to that in a group of women treated in an embryo-transfer programme who were being individually monitored, although there was evidence from cleavage rates and concentration of sex steroids in follicular fluid that further follicular maturation could have occurred. It is suggested that a modification of this schedule could provide an acceptable recovery rate of pre-ovulatory oocytes for research purposes, and possibly by simplifying the monitoring technique could be applicable to a wider range of patients seeking embryo transfer.

Androgens↗