Biomedical subjects
Publications and source records attributed to R Forman.
Part I of this series presented a review of the literature on Burning Mouth Symptoms (BMS) focusing on its prevalence, its symptoms, and proposed local etiologic factors associated with the condition. Part II will focus on the possible systemic and psychological etiologic factors in order to provide the dental clinician with a perspective on the alternative factors that may cause BMS.
A retrospective analysis was performed in order to compare the number and quality of oocytes recovered in in-vitro fertilization cycles according to different protocols for ovarian stimulation. Treatments including a gonadotrophin-releasing hormone agonist (GnRHa), either decapeptyl or buserelin, were associated with the recovery of more oocytes (6.0-7.2%) than treatments without GnRHa (3.7-4.8%). However, the mean number of normal embryos per patient yielding oocyte(s) was comparable between cycles stimulated with or without GnRHa (2.4-2.7), except in those cycles programmed with norethisterone and gonadotrophins (1.7). There was no difference in the rates of immature or atretic oocytes between stimulation treatments. Following clomiphene and human menopausal gonadotrophin treatment there was a lower rate of fractured zona oocytes, higher rates of fertilization and normal growth of fertilized eggs than after any other treatment. The proportion of normal embryos per recovered oocyte was inversely related to the degree of ovarian response in most of the stimulation treatments. Most of the abnormal embryos contained more than two pronuclei in cycles without GnRHa administration and exhibited polynucleated blastomeres in cycles treated with buserelin or decapeptyl. In conclusion, the use of GnRHa and gonadotrophins for ovarian stimulation increased the mean number of recovered oocytes, but did not increase the mean number of embryos able to develop.
The proportion of abnormal oocytes or embryos per recovered oocyte in in-vitro fertilization (IVF) cycles had no influence on the occurrence of pregnancy following the transfer of normal embryo(s) derived from oocytes capable of fertilization. There were more implantations per transferred embryo in stimulated IVF cycles using long-acting buserelin (30.0%) compared with short-acting decapeptyl (17.3%) or no gonadotrophin-releasing hormone agonist (GnRHa, 15.2%) treatments. However, the chances of implantation per embryo transferred being in excess of one in patients who became pregnant tended to be higher in non-GnRHa (23.5%) compared to buserelin- (16.4%) or decapeptyl- (13.3%) treated IVF cycles. Moreover, frozen--thawed embryos had a higher implantation rate (P less than 0.05) when originating from IVF cycles without GnRHa (11.7%) compared to GnRHa-treated cycles (buserelin, 4.3%; decapeptyl, 5.9%). It can be concluded that GnRHa associated with gonadotrophins produced embryos of a poorer aptitude for development than stimulation treatments without GnRHa. The clinical efficacy of GnRHa in IVF--ET cycles could be the result of an improved uterine receptivity to the transferred embryos.
Multiple follicular stimulation for IVF may be associated with greatly elevated serum E2 concentrations that are presumed to be antinidatory. This factor was analyzed in 825 consecutive embryo transfer cycles. The pregnancy rate decreased significantly after the transfer of one and two embryos in association with preovulatory E2 levels greater than the 90th percentile for the group (2320 pg/ml). The pregnancy rate did not vary with preovulatory E2 concentration following the transfer of three embryos. Highly significant correlations were noted between preovulatory E2 and early luteal phase concentrations of E2 and P. In a subgroup of 245 cycles, there were no significant relationships between implantation and early luteal phase levels of P or the ratio of E2/P. There was a small but nonsignificant tendency for the pregnancy rate to decrease in association with raised luteal E2. It is concluded that excessive E2 levels at the time of ovulation induction with hCG had an adverse effect on implantation when one or two embryos are transferred, but this may be overcome by the transfer of three embryos. The consequences for embryo transfer are discussed.
Luteinizing hormone-releasing hormone (LH-RH) agonists are being increasingly used in ovulation stimulation protocols in IVF programs. The results of two methods of utilization of LH-RH agonists are compared. In the long protocol, gonadotropin stimulation was commenced only after a preliminary period of pituitary desensitization with LH-RH agonist. In the short protocol, exogenous gonadotropins were administered shortly after the start of LH-RH agonist therapy, benefiting from the gonadotropin flare up effect. One hundred eighty-six patients were equally divided between the two treatments. There was no difference in the ovarian response on the day of human chorionic gonadotropin (hCG) or the number of mature oocytes recovered. The cleavage rate of mature oocytes was higher in the short protocol (70% versus 56% P less than 0.01). The ongoing pregnancy rate per treatment cycle was similar in both groups (18% in the long protocol and 16% in the short protocol). Analysis of the luteal phases revealed a trend for higher progesterone values in the long protocol although this was only significant on the 2nd day following oocyte retrieval. As the clinical results were similar, other factors should be taken into account when deciding therapy. These include patient convenience, cost, and side effects. Other schedules of ovulation stimulation with LH-RH agonists are discussed.
LHRH agonists are being increasingly used in ovulation stimulation protocols in IVF programmes. We have compared the results of two methods of utilization of LHRH agonists. In the long protocol, gonadotrophin stimulation was only commenced after a preliminary period of pituitary desensitization with LHRH agonist. In the short protocol, exogenous gonadotrophins were administered shortly after the start of LHRH agonist therapy, benefiting from the gonadotrophin flare-up effect. One-hundred-and-eighty-six patients were divided equally between the two treatments. There was no difference in the ovarian response on the day of HCG or the number of mature oocytes recovered. The cleavage rate of mature oocytes was higher in the short protocol (70, versus 56, P less than 0.01). The ongoing pregnancy rate per treatment cycle was similar in both groups (18, in the long protocol and 16, in the short protocol). Analysis of the luteal phases revealed a trend for higher progesterone values in the long protocol although this was only significant on the second day following oocyte retrieval. As the clinical results were similar other factors should be taken into account when deciding therapy. These include patient convenience, cost and side-effects. Other schedules of ovulation stimulation using LHRH agonists are discussed.
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Freezing and thawing procedures did not affect the chances of successful transfer of human embryos. The postimplantation viability of frozen-thawed embryos was equivalent to that of fresh, immediately transferred embryos. Selection of the embryos that were more suitable for freezing did influence the pregnancy rate after transfer of the remaining fresh embryos. The therapeutic efficacy of in vitro fertilization and embryo transfer programs will be greatly increased if only one embryo is transferred in the in vitro fertilization cycle, the others being separately frozen for further embryo transfer in subsequent cycles.
Although the physical treatment of semen for IVF and related procedures is sufficient to remove most organisms present in semen, the pathogenic varieties tend to be more resistant. The supplementation of oocyte culture medium with both penicillin and streptomycin was associated with the eradication of 100% of organisms in the current study. In these circumstances, the presence of pathogenic organisms in the untreated semen is not associated with reduced oocyte fertilization in vitro.
Certain factors influencing the success of embryo cryopreservation were analyzed from 124 cycles of in vitro fertilization and embryo transfer (IVF-ET) program in which 193 1- or 2-day embryos were frozen and had already been thawed. There were 100 transfers of one or two surviving embryos from which 26 pregnancies were initiated. Several factors significantly influenced embryo survival after thawing. They were: the developmental stage of frozen embryos; the appearance of the embryo at the time of freezing; and the mode of ovarian stimulation in the IVF cycle. The pregnancy rate after frozen-thawed embryo transfer was higher with 4-cell frozen embryos than with embryos at all other stages combined. There were also tendencies for the pregnancy rate to be higher if a spontaneous luteinizing hormone surge occurred in the transfer cycle or if the duration of embryo storage did not exceed 1 to 2 months. The results obtained support a new policy in IVF-ET programs: it should be advantageous for the sterile couple if the immediate fresh embryo transfer is only performed with the categories of embryos that demonstrate a poor aptitude for survival following cryopreservation procedures.
Semen specimens from 519 men were cultured for organisms 2 weeks before oocyte recovery for in-vitro fertilization (IVF). The cultures from 72 men contained more than 5000 bacteria/ml and the IVF attempt was postponed. The IVF outcome was assessed in 382 couples in relation to the semen culture result. The pregnancy rate per cycle was significantly reduced when the semen culture contained organisms compared with axenic semen (P less than 0.05). This was independent of the cleavage rate of oocytes and the number of embryos transferred. Although mycoplasma was frequently cultured, chlamydial infection was very rare and no viruses were isolated in this study.
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Fixed-schedule ovulation induction and cryopreservation of the obtained embryos was performed in women undergoing a preliminary laparoscopy for infertility investigation before possible inclusion in an in vitro fertilization program. The cycle before follicular stimulation was modified by a progestogen or an estrogen-progestogen contraceptive pill. Ovarian inaccessibility precluded follicular aspiration in four of 34 patients but at least one oocyte was obtained in 29 of the remaining 30. Although fewer oocytes were obtained in these patients than in a control group undergoing in vitro fertilization treatment, one or more embryos were obtained in 22 patients in the study group. All embryos were frozen and to date 25 embryos from 17 patients have been thawed. Embryos have been placed in 16 of the 17 patients and six pregnancies have been initiated. Three are currently ongoing, one ectopic pregnancy was recorded, and two pregnancies were classified as "chemical." Programmed oocyte retrieval and embryo cryopreservation resulted in an extra chance of pregnancy in patients undergoing a laparoscopy for infertility investigation.
Human embryos produced by in vitro fertilization (IVF) were frozen with 1,2-propanediol as a cryoprotectant. Embryo survival after thawing was related to the presence of a nucleus in frozen cells and decreased with the increasing number of cells in the frozen embryo. None of five embryos frozen 3 or 4 days after IVF survived when thawed. Of 48 early embryos (35 patients) frozen 1 or 2 days after IVF, 42 (87.5%) were transferred in 32 patients. Ten pregnancies were initiated after frozen embryo transfer (ET). If we exclude the three infertile patients who had sexual intercourse in the fertile period, the pregnancy rate for each patient who had 1- or 2-day frozen embryo(s) was 22% (7 of 32). One of the pregnancies was obtained after ET of a 1-cell pronucleated frozen and thawed embryo. The rate of ongoing pregnancies after triple fresh ET was 23%. In patients having four embryos obtained in a single IVF cycle, the expected overall liveborn rate in an IVF-ET program including embryo cryopreservation could theoretically equal that of natural human fertility.
Programed oocyte retrieval was performed in a group of 35 patients undergoing in vitro fertilization (IVF) treatment. The date of follicular aspiration was decided several months in advance and the cycle prior to oocyte recovery was modified with a progestagen or an estrogen-progestagen contraceptive pill. This was followed by a fixed-schedule ovulation stimulation and induction regimen. Follicular growth was not monitored. Thirty-four of the 35 patients had follicular aspiration, and at least one embryo was obtained in 30 of them. The clinical pregnancy rate (excluding cryopreserved embryos) was 20% per IVF cycle, 21% per attempted oocyte retrieval procedure, and 23% per embryo transfer cycle. Programmed oocyte retrieval is a realistic option for follicular stimulation for IVF treatment and is associated with significant practical and economic benefits.
A single identified neuron, the medial type B photoreceptor, was isolated by axotomy from the nervous systems of nudibranch molluscs (Hermissenda) which had been exposed to three different training experiences. Paired animals had been trained with repeated paired presentations of light and rotation and random animals with randomized light and rotation; naive animals had no training. A two-microelectrode voltage clamp of axotomized type B somata (separated from all synaptic interactions and impulse activity) was used to measure, with a blind procedure, three distinct ionic currents at least 24 h after the training experience. An early K+ current, IA, and a Ca2+-dependent K+ current, ICa2+-K+, but not a light-induced inward Na+ current, were significantly reduced for the paired as compared to the random and naive animals. The magnitude of ICa2+-K+ reduction was related (again measured blindly) to the degree of training-induced suppression of phototaxis (a measure of the learned behavior) for the paired animals. These data are consistent with previous observations indicating that changes of intrinsic type B membrane properties are an important means for encoding the acquisition and retention of Hermissenda associative learning.
This study was undertaken to quantitate the lateral extension that occurs concomitantly with the transmural extension of a subendocardial infarction. A subendocardial infarct was produced in 12 dogs by a 40 minute temporary coronary artery occlusion. Infarct extension was induced 7 days later by permanent occlusion of the same vessel. Regional myocardial blood flows confirmed that ischemia had been produced with both coronary artery occlusions. The vascular boundaries between the normally perfused and ischemic beds were defined by perfusion with different-colored Microfil solutions. The extent of subendocardial infarction and subsequent transmural and lateral extensions were assessed by point counting of histologic specimens. The initial temporary occlusion produced a 30.0 +/- 4.2% transmural infarct and the subsequent permanent occlusion a 29.2 +/- 3.5% transmural extension in a risk region of 39 +/- 4 g. Lateral extension was not measured in four dogs because the initial subendocardial infarct was patchy with markedly irregular lateral borders. In eight dogs the size of the measured lateral infarct extension from each lateral margin from two histologic sections was 0.63 +/- 0.013 cm2. The area of both lateral extensions was 1.7 +/- 0.1% of the cross-sectional area of its risk region as determined by planimetry. Using a model of the risk region, the mass of the lateral extension was estimated to be 1.4 +/- 0.3 g or 3.5 +/- 0.6% of the region at risk. Thus, at the lateral margin of a subendocardial infarct there is a border zone that is small relative to the size of the region at risk and infarcted myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)
Hormonal stimulants of ovarian follicular maturation and anesthesia/surgery were examined for their effects on the concentration of plasma and follicular fluid PRL. Forty-seven patients undergoing in vitro fertilization for the treatment of infertility were selected at random for this prospective study. Patients given human menopausal gonadotropin and clomiphene citrate had significantly higher levels of plasma PRL compared to those given clomiphene only. Anesthesia/surgery elevated plasma PRL levels in all patients, by as much as 50-fold and to as high as 7878 mIU/liter. Follicular fluid PRL levels were correlated with preanesthetic plasma PRL concentrations, but the latter were not correlated with plasma 17 beta-estradiol. Elevated plasma or follicular fluid PRL concentrations had no effect on in vitro fertilization of oocytes or embryonic development. Although not significant, the incidence of pregnancy was highest in the group of patients with the lowest preanesthetic plasma PRL levels.