Biomedical subjects

P Bischof

Publications and source records attributed to P Bischof.

148 records · Page 9Linked to original sources

PubMedDate not supplied

A model for implantation of the human blastocyst and early placentation.

We describe here a molecular model of blastocyst implantation which is based on two assumptions: (i) that implantation of the human blastocyst into the endometrium is a process which is very similar to tumour invasion of a host tissue; and (ii) that the cytotrophoblastic cells of a first trimester pregnancy retain almost all the properties of the trophectodermal cells of the blastocyst and can thus be used as surrogates to study the implantation process in vitro. Our model considers that the trophectodermal cells, once they reach the endometrial basement membrane, express integrins (alpha 6 beta 4) which anchor them into the basement membrane and induce their secretion of gelatinases. These proteases digest the basement membrane, allowing the embryo to make contact with the endometrial extracellular matrix (ECM). Integrins (alpha 5 beta 1) anchor the embryo into the ECM and induce its secretion of collagenases. These enzymes digest the ECM, allowing the embryo to burrow into the endometrium. This process is under the paracrine control of endometrial cytokines and ECM glycoproteins.

Blastocyst↗

PubMedDate not supplied

Leptin and reproduction.

Leptin, the product of the ob gene, is a small peptide molecule synthesized by white adipocytes with an important role in the regulation of body fat and food intake. Leptin and leptin receptor mRNA were first detected in the brain and hypothalamus but now their ubiquitous presence has been demonstrated. Leptin receptor signal transduction involves the activation of signal transducer and activator of transcription (STAT)-3, a member of the transcription family of proteins. Leptin is regulated by hormones and cytokines, interleukin-1, tumour necrosis factor-alpha and transforming growth factor-beta, linking this molecule with the inflammatory response. In addition, emerging evidence has demonstrated that this molecule is related to reproductive function. This small protein is present in the ovary and decidua, in mature oocytes and during embryonic development and trophoblast invasion. Animal models have demonstrated that leptin-deficient ob/ob mice are sterile; however, fertility can be restored by exogenous leptin. In addition, embryos implanted in STAT-3-deficient mice degenerate rapidly and are the target disruption of STAT-3-provoked embryonic lethality. Leptin acts as a novel placental hormone participating in the control of fetal growth and development. Leptin could be a modulator for invasive features of cytotrophoblast cells. We postulate that leptin may have an autocrine/paracrine role in human implantation and placentation.

Animals↗

PubMedDate not supplied

Expression of matrix metalloproteinase-2 and mutant p53 is increased in hydatidiform mole as compared with normal placenta.

Matrix metalloproteinases (MMPs) are group of enzymes thought to play an important role in trophoblastic and tumor invasion. The aim of our study was to investigate the trophoblastic expression of MMPs and p53 in normal trophoblast and hydatidiform moles (HM). Paraffin sections of 45 specimens, including 14 complete hydatidiform moles (CM), 15 partial hydatidiform moles (PM), 8 atypical partial hydatidiform moles (aPM), and 8 controls were selected. Classification of HM was established on histologic criteria and supported by the DNA ploidy results. Tissue sections from each case were immunostained with monoclonal antibodies, cytokeratin-7, MMP-2, MMP-9, tissue inhibitors of metalloproteinases (TIMP)-1, and p53 wild type (p53wt) and mutant types (mutp53). Staining for cytokeratin-7 revealed a positive reaction in 93% of the samples. MMP-2 was mainly expressed in the syncytiotrophoblast of HM and found in 62% of aPM, 60% PM, and 93% CM. The mutp53 was mainly and focally expressed in syncytiotrophoblastic cells and was found in 63% of aPM, 80% PM, and 93% CM. Expression of MMP-2 and mutp53 was both significantly greater in HM vs control group (P < 0.05) and greater in CM vs PM and aPM (P < 0.05). No significant difference was observed for cytokeratin-7, MMP-9, TIMP-1, and p53wt between the HM subgroups and between HM and control group. MMP-2 and mutp53 are overexpressed in HM as compared with normal trophoblast and might participate in the invasive behavior of the HM.

Adolescent↗

PubMedDate not supplied

Relationship between etiological factors and total motile sperm count in 350 infertile patients.

The prevalence of different etiologic factors has been evaluated in 350 male patients consulting the same physician in an urban, ambulatory setting for primary or secondary infertility of more than 1 year. Environmental factors such as alcohol or drugs represented 12% of the etiologies, acquired diseases such as varicocele and prostatitis 40%, congenital diseases and primary testicular failure 16.2%, idiopathic cases 19.4%, and abnormality of sperm transport 7.4%. The severity of sperm alterations in the different etiologic categories was evaluated by the total motile sperm count per ejaculate (TMS) (normal > 16). The TMS was less than 5 in classical causes of male infertility such as testicular failure, endocrinopathy, cancer, or antisperm antibodies. It was more than 10 in controversial causes of infertility such as varicocele, prostatis, chlamydial infections, and professional exposure to heat. After treatment, there was a nonsignificant increase of the TMS in the latter cases. In cases of azoospermia of pituitary origin, the TMS was normalized by a hormonal treatment. In some cases of azoospermia of possible obstructive origin, sperm appeared in the ejaculate after diclofenac treatment. The utility of andrological investigation and treatment is discussed.

Adult↗