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Biomedical subjects

B Lefèvre

Publications and source records attributed to B Lefèvre.

At least 37 records · Page 2Linked to original sources
PubMed1991

Local anaesthesia with intravenous analgesia as an alternative to general anaesthesia for medically compromised patients undergoing oral surgery. A retrospective study of sixty-two cases.

The purpose of this retrospective study was to evaluate the combined use of intravenous analgesia, with a potent opiate alone, supplemented by local anaesthesia as an alternative to general anaesthesia for medically compromised patients. Sixty-two in-patients, aged between 32 and 80 years, with an ASA physical status of III and IV, were involved in this study. The local anesthetic used was 4% articain with epinephrine (1:200,000) and narcotic analgesics were Fentanyl or Alfentanil. Surgical procedures included multiple dental extractions, cystectomy and the removal of impacted teeth. All patients completed the surgery without deeper anaesthesia and mostly enjoyed a comfortable intraoperative period. Only one respiratory depression was observed, but quickly reversed. Other adverse effects were few and without consequences, hemodynamic changes remained in tolerable limits. In conclusion this anaesthetic technique can be a suitable alternative to general anaesthesia in oral surgery for high-risk patients.

Adult↗
PubMed1991

[The Akinosi dental anesthesia technique: apropos of 10 clinical cases].

The anesthesia technique described by AKINOSI in 1977, in Nigeria, shows certain advantages: According to the author, it has a percentage of efficacy, of about 95%. It permits an effective anesthesia of the inferior alveolar, lingual and buccal nerves to be obtained with a single injection. It has a psychological aspect which is of interest to the degree that it is carried out with the mouth closed, the patient thus being in a position of muscular and aponeurotic relaxation, which permits a nearly painless injection to be made. This technique has disadvantages which lead to a preference for the "Spix spinal" technique, each time that it is indicated; the onset is longer than the one at the Spix an average of 6 minutes (for all nerves) as seen in this study, but above all, it is a high vascular risk technic that can be conceived only if perfect knowledge of the pterygo-mandibular region has been gained so as to evaluate the vascular proximities, essentially the maxillary artery and the pterygoïd veinous plexas.

Adolescent↗
PubMed1991

[Cranio-maxillo-facial fibrous dysplasia].

The fibrous dysplasia of the bones is a big disease, but it has to be considered as an expansive process with local malignancy in the cranio-maxillo-facial localizations. After a review of the literature, 7 cases of fibrous dysplasia are presented. The only curative treatment is surgical, generally mutilating, it has to be completed by a restoring intervention in same time. The abstention and the modeling surgery can be indicated exceptionally, it requires a regular X ray examination, and a clinical follow-up.

Adolescent↗
PubMed1990

[Primates in the study of oocyte maturation].

In the mammalian oocyte, meiosis is initiated during fetal life. Meiosis proceeds up to the diplotene stage of the first prophase and is arrested at birth and the oocyte presents a nuclear structure known as germinal vesicle (GV). Meiotic arrest persists until sexual maturity, when one or more oocytes, the number dependent on the species, reinitiate their reduction division at each cycle. The series of event, initiated by the breakdown of the germinal vesicle (GVBD) and completed with formation of the polar body, leads to the production of a mature, fertilizable oocyte, and is defined as oocyte maturation. Maturation of the oocyte is an essential prelude to fertilization. Normally the meiosis is reinitiated by the preovulatory LH peak but when meiotically arrested oocytes are removed from the antral follicles, they resume meiosis spontaneously in vitro. However primate (human and monkeys) oocytes isolated from antral follicles and cultured within their cumuli for two days, spontaneously resumed meiosis at a very low rate (less than 30%) compared to other mammals. Cynomolgus monkey oocyte then appears as a good model for in vitro studies of maturation initiation. Follicular atresia improve significantly the GVBD rate (about 50%). The cumulus cell mass takes an important part in the maintenance of the meiotic arrest since its mechanical removal is followed by an increase of the GVBD (P less than 0.02). A gonadotropin releasing hormone agonist (GnRHa) and a protein kinase C activator added to the culture medium both improve the GVBD (54% and 55% respectively, P less than 0.01). The GnRHa oocyte maturation induction is probably protein kinase C dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

In vivo changes in oocyte germinal vesicle related to follicular quality and size at mid-follicular phase during stimulated cycles in the cynomolgus monkey.

Histological examination of gonadotrophin stimulated Macaca fascicularis ovaries removed at mid-follicular phase showed that germinal vesicles (GV) could exhibit different configurations in follicles greater than 1000 microns in diameter. We describe 3 types of nuclear organization called GV1 (dispersed and filamentous chromatin), GV2 (clumped and filamentous chromatin) and GV3 (perinucleolar chromatin condensation). Gonadotrophin stimulation and follicular atresia induced modifications in GV chromatin dispersion. Such modifications were of a higher degree in the case of atresia which could even induce in vivo germinal vesicle breakdown (GVBD). Our findings were as follows. The frequency of GV1 oocytes was always low, but was higher in healthy than in atretic follicles, whereas GV3 oocytes were more frequent in atretic compared to healthy follicles; the oocytes which resumed meiosis in vitro were most probably those which were at the GV3 stage at the time of recovery; GV nuclear changes were related to follicle size and quality, but not to oocyte size. The mean follicular size increased from GV1 to GV3 oocyte stages whatever the follicle quality; the nucleus was often observed in a peripheral position even in GV1 oocytes; zona pellucida appearance was related to GV stage and follicle quality and was more often observed to be abnormal or absent in case of GV3 oocytes included in atretic follicles. Oocyte nuclear modifications therefore appear to be a prerequisite to resumption of meiosis.

Animals↗
PubMed1989

[Development of chloroquine resistance in Plasmodium falciparum in Gabon between 1984 and 1987-88 (in vivo evaluation in a school environment)].

Unknown in 1980, suspected in 1983 and scarcely present in 1984-85, Plasmodium falciparum resistance to chloroquine as studied in vivo in schoolchildren in Gabon, has strongly developed in 4 years time. In 1987-88, administration of 25 mg/kg of chloroquine leaves one strain out of four with a parasitic load greater than 10/1.000 red blood cells examined by thick drop technique. The present, unfortunately provisional attitude tends to maintain chloroquine at efficient doses for as long as the resistant strains are ethically and practically controllable. The dispersion without strict control of new and for the time being very efficient drugs might rapidly give rise to a polychemoresistance which would leave us without defence.

Animals↗
PubMed1988

A gonadotropin-releasing hormone agonist and an activator of protein kinase C improve in vitro oocyte maturation in Macaca fascicularis.

Cynomolgus monkey oocytes were recovered from follicles greater than 1,000 microns in diameter at day 8 in gonadotropin-stimulated cycles and cultured in vitro for 2 days. Germinal vesicle breakdown (GVBD) occurred in 30.3% of control oocytes (n = 76) compared with 54.0% and 55.0% of oocytes cultured in presence of a gonadotropin-releasing hormone agonist (GnRHa), Buserelin (n = 50), or a protein kinase C activator, 1-oleoyl-2-acetyl-racglycerol (OAG, n = 40), respective (P less than .01). As similar results were obtained using OAG or Buserelin, we hypothesize that the action of Buserelin upon the primate oocyte is protein-kinase-C dependent. The possible effects of Buserelin on in vivo oocyte maturation have to be determined.

Animals↗
PubMed1988

Effect of cumulus cell mass and follicle quality on in-vitro maturation of cynomolgus monkey oocytes.

Cynomolgus monkey oocytes were recovered from healthy or atretic follicles greater than 1000 micron in diameter at day 8 of gonadotrophin stimulated cycles and cultured in vitro, cumulus enclosed or cumulus free, for 2 days. Germinal vesicle breakdown (GVBD) occurred in 26.7% of healthy cumulus enclosed oocytes (n = 60) compared to 52.6% of atretic cumulus enclosed oocytes (n = 38). The mechanical removal of the cumulus cell mass increased the GVBD rate of the healthy oocytes (56.5%, n = 23) and accelerated the passage of the atretic oocytes (n = 23) from metaphase I (4.3%) to metaphase II (47.8%). In the healthy primate follicle, the dictyate stage could be maintained by an inhibitory substance secreted by the cumulus; follicular atresia could either decrease the synthesis of this substance and/or induce the metabolism of a stimulatory substance.

Animals↗
PubMed1987

In-vitro oocyte maturation: some questions concerning the initiation and prevention of this process in humans.

Human oocytes isolated from healthy non-preovulatory antral follicles which had not been stimulated spontaneously resumed meiosis at a low rate (31%) when compared with those from atretic follicles (73%). Human follicular fluid did not inhibit spontaneous maturation of rat oocytes in vitro, regardless of the quality or maturity of the follicle or the treatment of the patient. In the human, oocyte maturation may involve a stimulatory process as well as a removal of inhibition.

Animals↗
PubMed1985

Factors affecting human in vitro fertilization: a multifactorial study.

The influence of four factors on the cleavage rate of 705 mature oocytes submitted for in vitro fertilization (IVF) was assessed with the use of a multifactorial method, i.e., logistic regression. The studied factors were (1) the regimen for cycle stimulation, (2) cumulus cell mass appearance, (3) semen quality, and (4) the time of incubation of oocytes before insemination. The logistic function permitted testing the respective influence of each factor on the cleavage rate, with the level of the other factors taken into account. The most important factor was the stimulation treatment, the association of human menopausal gonadotropin with clomiphene citrate (CC) giving better results than CC alone. Time of incubation was demonstrated to have no influence on the cleavage rate, whereas semen quality had an influence. A problem was raised by the existence of an interaction between the stimulation treatment used and the appearance of the cumulus cell mass. It can be concluded that adequate cycle treatment and eventually couple selection with respect to the semen quality of the male partner are to be considered in view of obtaining better results in IVF attempts.

Adult↗
PubMed1984

Histological evidence of alternating ovulation in women.

Detailed histological analysis of ovaries obtained from 25 women by ovariectomy for medical reasons demonstrated that the degeneration of the cyclic corpus luteum is a long process, taking several cycles. The ages of the various regressing corpora lutea were identified to permit classification of the side of ovulation during the preceding 4 or 5 cycles. In the 25 women studied, with regular menstrual cycles of 28 +/- 3 days (48 cycles), ovulation occurred most often (87.6%) in an alternating manner.

Adult↗
PubMed1983

In-vitro ovulation of rabbit ovarian follicles isolated after the endogenous gonadotrophin surge.

Follicular rupture was never observed when preovulatory rabbit follicles were isolated from the ovary before the ovulatory gonadotrophin discharge and placed in hormone-free culture for 10-14 h (n = 48). However, if the follicles were taken 1 h post coitum and cultured under the same conditions, 11/24 (45.8%) ruptured spontaneously. Follicular rupture under these conditions appeared to be chronologically and histologically comparable to that of ovulation in vivo. Culture in the presence of progesterone increased the proportion of follicles ovulating in vitro (17/23 = 73.9%; P less than 0.05). Inhibition in vitro of the synthesis of steroids or prostaglandins suppressed ovulation, although meiotic maturation of the oocyte did take place. These findings indicate that the follicle constitutes an independent entity within the ovary from 1 h post coitum.

Animals↗
PubMed1983

Role of the extra-follicular compartment in the ovulation of isolated rabbit ovarian follicles.

Ovulation was never observed, even in the presence of gonadotrophins, when preovulatory follicles isolated from oestrous does were cultured in vitro (n = 112). If the follicles were co-cultured with pieces of ovarian tissue and gonadotrophins, then 50% ovulated (P less than 0.01). Attempts to replace the ovarian tissue by various steroid hormones or prostaglandins did not result in follicular rupture except when PGE-2 was used (23.8%, P less than 0.05). We suggest that gonadotrophins have an immediate (less than 1 h) action upon the follicle and ovarian interstitial tissue simultaneously. The response of the ovarian tissue to gonadotrophins is essential for eventual follicular rupture and involves PGE-2.

Androstenedione↗
PubMed1983

Evolution of the diameters of the largest healthy and atretic follicles during the human menstrual cycle.

Analysis of ovaries from 31 women with normal ovarian function permitted study of the diameter of the largest healthy and atretic follicles during the menstrual cycle. The follicle destined to ovulate is selected during the early follicular phase (Days 1-5). Throughout the cycle the diameter of the largest healthy follicles, with the exception of the dominant follicle, did not exceed, on average, 6 mm during the follicular phase and 4 mm during the luteal phase. Consequently, excluding the dominant follicle during the second half of the follicular phase, the largest follicles present in the human ovary are atretic. From these data, it was concluded that a new ovulation could not occur very soon after a spontaneous or experimentally induced premature disappearance of the dominant follicle or the corpus luteum of the cycle.

Adult↗