Biomedical subjects

R A Prefetto

Publications and source records attributed to R A Prefetto.

4 recordsLinked to original sources

PubMed1994

Dysfunctional uterine bleeding (DUB).

Cyclic or irregular uterine bleeding is common in perimenarchal and perimenopausal women with or without endometrial hyperplasia. The disturbance often requires surgical treatment because of its negative effects on both blood loss and abnormal endometrial growth including the development of endometrial cancer. The endometrium is often overstimulated during the perimenopausal period when estrogen/progesterone production is unbalanced. A therapeutical approach with gonadotropin-releasing hormone agonist (GnRHa) was proposed in a depot formulation (Zoladex) that induces a sustained and reversible ovarian suppression. To avoid the risk of osteoporosis and to obtain adequate endometrial proliferation and differentiation during ovarian suppression, transdermal 17-beta-estradiol and oral progestin were administered. Results of 20 cases versus 20 controls showed a reduction of metrorrhagia, a normalization of hemoglobin plasma concentration, and an adequate proliferation and secretory differentiation of the endometrium of patients with abnormal endometrial growth. Abnormal uterine bleeding is mainly due to uterine fibrosis and an inadequate estrogen and/or progesterone production or to a disordered estrogen transport from blood into the endometrium. In premenopausal women, endometrial hyperplasia may be part of a continuum that is ultimately manifested in the histological and biological pattern of endometrial carcinoma. The regression of endometrial hyperplasia obtained by using the therapeutic regimen mentioned above represents a preventive measure for endometrial cancer. Finally the normalization of blood loss offers a good medical alternative to surgery for patients with DUB.

Adult↗

PubMed1994

Immunologically mediated abortion (IMA).

Roughly 20% of all clinical pregnancies evolve into "spontaneous abortions". The causes of spontaneous abortion have been determined in under 60% of the total and comprise genetic, infectious, hormonal and immunological factors. In some cases the immune tolerance mechanism may be impaired and the foetus immunologically rejected (IMA, immunologically mediated abortion). The immunological mechanism implicated depends on the time in which pregnancy loss takes place. During preimplantation and up to the end of implantation (13th day) the cell-mediated immune mechanism (potential alloimmune etiologies) is responsible for early abortion. This mechanism involves immunocompetent decidual cells (eGL, endometrial granulated lymphocytes) already present during pre-decidualization (late luteal phase) and their production of soluble factors or cytokines. Once the implantation process is over, after blastocyst penetration of the stroma and the decidual reaction of uterine tissue, IMA could be caused by cell-mediated and humoral mechanism (anti-paternal cytotoxic antibodies or autoantibody etiology), by the production of paternal anti major histocompatibility complex antibodies, or even by an autoimmune disorder leading to the production of autoantibodies (antiphospholipid antibodies, antinuclear antibodies or polyclonal B cell activation). The diagnostic work-up adopted to select IMA patients is crucial and includes primary (karyotype of both partners, toxo-test, hysterosalpingography, endometrial biopsy, thyroid function tests, serum hprolactin, luteal phase dating) and secondary (full hemochromocytometric test, search for LE cells, lupus anticoagulant, anticardiolipin, antinuclear antibodies, Rheumatoid factor, blood complement VDRL) investigations. Therapeutical approaches vary. If autoimmune disorders are demonstrated therapies with different combinations of corticosteroids, aspirin and heparin or intravenous immunoglobulin are administered. Otherwise, therapy with paternal or donor peripheral blood mononuclear cells should be instituted.

Abortion, Spontaneous↗

PubMed1993

Electromechanical activities of human uteri during extra-corporeal perfusion with ovarian steroids.

A new experimental system was designed to study human uterine activities based on the extra-corporeal perfusion of isolated human uteri. Electromechanical activities in the uterine wall were recorded using bipolar silver-silver electrodes, endoluminal pressure catheters and a dedicated acquisition, storage and analytical system. The electrical signals recorded were isolated spikes and rhythmic activities; the last being primarily associated with organized mechanical events. Perfusion media containing 17 beta-oestradiol alone or with progesterone were used for those uteri obtained during proliferative (n = 5) or secretory (n = 5) phases of the menstrual cycle, respectively. Progesterone caused a reduction of frequency (P < 0.001) and duration (P < 0.001) of the rhythmic electrical activity, and decreased the endoluminal pressure at both detection sites (P < 0.01). 17 beta-Oestradiol increased both frequency (P < 0.001) and duration (P < 0.001) of the rhythmic electrical activity as well as the endoluminal pressure at two different detection sites (3 and 5 cm from the fundus) (P < 0.05). Significant differences between the fundus and cervix sites in the uterine wall were detected. In conclusion, uterine perfusion would be useful to examine the effects of uterotonic and tocolytic drugs before administration to humans, at no risk to the patients. Oestrogens increase and progesterone decreases both electrical and mechanical uterine activities.

Action Potentials↗

PubMed1991

Factors regulating interaction between trophoblast and human endometrium.

Implantation is a crucial step in human reproduction. Disturbances of this process are responsible for pregnancy failure after both in vivo and in vitro fertilization. The endometrium provides the implanting embryo with a unique substratum where the embryo communicates with biochemical signals, attaches itself, penetrates and grows without blood circulation. The highly proliferative phase of the cytotrophoblast, during early human embryogenesis, may be due to endogenous production of growth factors that may establish autocrine/short range paracrine stimulator loops which explain the tumor-like properties of these tissues. Endometrial BM penetration and stroma invasion may be due to the proteolytic capability of the human embryo. It is suggested that collagenase and the urokinase-like plasminogen activator are responsible for this activity. To clarify the molecular mechanisms involved in human embryo implantation several models are suggested: culture of blastocysts, culture of endometrial cells, and endometrial explant co-culture. Human blastocysts cultured with whole perfused human uteri make it possible to recognize some aspects of the entire implantation process and give us the possibility of improving the benefits provided by new technologies in reproductive medicine and reducing embryonic loss at an early stage.

Endometrium↗