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H Lei

Publications and source records attributed to H Lei.

At least 73 records · Page 4Linked to original sources
PubMed1997

Disruption of alpha3 connexin gene leads to proteolysis and cataractogenesis in mice.

Gap junction channels formed by alpha3 (Cx46) and alpha8 (Cx50) connexin provide pathways for communication between the fiber cells in the normal transparent lens. To determine the specific role of alpha3 connexin in vivo, the alpha3 connexin gene was disrupted in mice. Although the absence of alpha3 connexin had no obvious influence on the early stages of lens formation and the differentiation of lens fibers, mice homozygous for the disrupted alpha3 gene developed nuclear cataracts that were associated with the proteolysis of crystallins. This study establishes the importance of gap junctions in maintaining normal lens transparency by providing a cell-cell signaling pathway or structural component for the proper organization of lens membrane and cytoplasmic proteins.

Aging↗
PubMed1997

Species differences in the expression of major histocompatibility complex class II antigens on coronary artery endothelium: implications for cell-mediated xenoreactivity.

BACKGROUND: There is controversy in the literature as to whether swine coronary endothelium expresses major histocompatibility complex (MHC) class II antigens constitutively. METHODS: Because this issue has implications for cell-mediated human anti-swine xenogeneic responses, we stained tissue sections from human, pig, rat, and mouse hearts with the anti-class II monoclonal antibody ISCR3, which has a similar specificity and titer when binding to human, porcine, and rodent class II molecules. RESULTS: Immunoperoxidase staining of human and porcine hearts with ISCR3 resulted in a dense reaction on the coronary endothelium of epicardial arteries, intramuscular arterioles, and capillaries. In contrast, the coronary endothelium of rat and mouse hearts did not stain with ISCR3. When freshly harvested porcine aortic endothelial cells were placed in culture, class II MHC antigen expression was lost within three to four passages. CONCLUSIONS: Thus, using a single antibody with cross-species reactivities, we demonstrate that swine coronary endothelium, unlike rodent coronary arteries, expresses similar basal amounts of class II MHC antigens to human coronary vessels. The constitutive expression of class II MHC antigens on swine coronary artery endothelium may contribute to host T cell-mediated xenogeneic responses in clinical pig-to-human cardiac xenotransplantation and thus become a target for therapeutic intervention.

Aged↗
PubMed1997

[Effects of total flavones of fructus Hippophae (TFH) on cardiac function and hemodynamics of anesthetized open-chest dogs with acute heart failure].

This study was carried out employing the model of dog with acute heart failure induced by phenobarbital natricum. It was shown that i.v. TFH 4.8 and 9.7 mg/kg could significantly increase CO, CI, + LVdP/dtmax and LVSP; shorten R-dP/dtmax in 9.7 mg/kg; raise - LVdP/dtmax, reduce LVEDP and T value; decrease MVO2I and TPVR; MAP and HR were not changed significantly. The results suggest that i.v. TFH can strengthen cardiac pump function and myocardial contractility in canine with heart failure; significantly improve myocardial diastolic function and hemodynamic performance; markedly decrease myocardia-used oxygen index and total peripheral vessel resistance, thus proving that TFH is good for heart failure.

Animals↗
PubMed1997

Using two preferred retinal loci for different lighting conditions in patients with central scotomas.

PURPOSE: Using a scanning laser ophthalmoscope, it was found that some patients with relative central scotomas reliably used two different preferred retinal loci (PRLs) at different stimulus illuminances. This article describes adaptations in a patient's PRL for fixation when dimming the stimulus increased the relative scotoma size. METHODS: Twenty-eight patients with macular diseases had their dense and relative macular scotoma borders mapped with the scanning laser ophthalmoscope. The high-illuminance PRL (PRLhi) and low-illuminance PRL (PRLlo) were operationally defined as the PRLs that patients used to fixate a high or low illuminance stimulus, respectively. The PRLs' abilities to do visual tasks and their characteristics at the corresponding illuminances were assessed. RESULTS: The PRL consistently shifted between the PRLhi and the PRLlo as the stimulus illuminance was changed. Brightness permitting, the visual system prefers to use the PRLhi with generally better performance in visual function such as fixation stability. There were no significant differences between the PRLhi and the PRLlo in pursuit and saccadic abilities, when assessed by subjective ratings. The illuminances that induced shifting ranged from 106 to 3437 trolands. The PRLhi was always located within an area of relative scotoma, usually at the fovea or just outside a dense scotoma. The PRLlo was located in relatively healthy retinal area, and usually below or to the left of the PRLhi in the visual field. CONCLUSIONS: In the visual system, two well-defined PRLs can develop when visual function is adapting to maculopathy, with the use of each depending on the brightness of objects used in visual tasks. Rehabilitation and treatment strategies should consider the existence of multiple PRLs.

Adaptation, Ocular↗
PubMed1997

Investigation of attitudes towards organ transplantation in young people in China.

OBJECTIVE: To investigate the attitudes toward organ transplantation, organ donation and recipients in young people in Beijing, Shanghai, and Wuhan. METHODS: A questionnaire was designed for 3012 young people aged 20-45 years (999 in Beijing, 990 in Shanghai, and 1023 in Wuhan). The data of questionnaire were processed with SPSS software. RESULTS: Over 90% of the respondents knew that human organs can be transplanted; over 85% considered that organ transplantation is a welfare undertaking; more than 85% thought that when someone's organ is in critical condition, it is necessary to perform organ transplantation; over 70% expressed willingness to receive organ transplantation if it is needed or possible. In the mode of organ donation, 70% emphasized that organ donation should be dependent on volunteers and the donor should be rewarded in a certain form. Organ recipients in sequence are relatives, specialized medical institutions, friends, members of volunteer organizations, and others. The factors affecting the attitudes towards organ transplantation are analyzed. CONCLUSION: There is a better attitude toward organ transplantation among young people in cities. The conventional attitudes and feudal habits are one of the major obstacles to the course of organ donation in China.

Adult↗
PubMed1997

[Investigation of understanding and willingness of organ transplantation in young people in Beijing, Shanghai, Wuhan].

OBJECTIVE: To understand the knowledge of young people in cities in China about organ transplantation and their willingness to donate organs, methods of donation, and the willingness of donators. METHODS: A questionnaire was designed in investigating 3,012 young people (999 questionnaires in Beijing, 990 in Shanghai, 1,023 in Wuhan) aged 20-45 years in the three cities. The data were processed by SPSS software. RESULTS: Over 90% of the people investigated knew that human organs can be transplanted 85% considered organ transplantation is a warefare undertaking. 85% thought organ transplantation is necessary when someone's organ is severely-impaired. If possible, 70% were willing to receive organ transplantation. With regard to forms of donation, over 70% emphasized the individual willingness combined with reimbursement. The Preferred recipient in sequence were relatives, special institutions, friends, volunteers, and others. The various factors. affecting understanding of organ transplantation were analysed. CONCLUSION: In cities of China, young people have a better understanding of organ transplantation, but conventional attitudes and feudal habits are the major obstacle to the development of organ transplantation in China.

Adolescent↗
PubMed1996

A program of cell death and extracellular matrix degradation is activated in the amnion before the onset of labor.

Fetal membranes usually rupture during the process of labor. Premature fetal membrane rupture occurs not infrequently and is associated with significant fetal and maternal morbidity. The mechanisms of normal and pathologic fetal membrane rupture are not well understood. We have examined structural and biochemical changes in the rat amnion as labor approaches in order to characterize this process in normal pregnancy. Here we report that before the onset of active labor the amnion epithelial cells undergo apoptotic cell death which encompasses degradation of 28S ribosomal subunit RNA and associated P proteins and fragmentation of nuclear DNA. Concurrent with these cellular changes, the amnion type I collagen matrix is degraded with the accumulation of three-quarter length type I collagen fragments in extraembryonic fluid, characteristic of the cleavage of fibrillar collagen by interstitial collagenase. Western blot and immunohistochemical analyses confirmed that interstitial collagenase protein appears in association with the loss of amnion type I collagen. We conclude that amnion epithelial cells undergo a process of programmed cell death associated with orchestrated extracellular matrix degradation which begins before the onset of active labor. Thus, fetal membrane rupture is likely to be the result of biochemical changes as well as physical forces.

Amnion↗
PubMed1996

Complete phenotypic characterization of apobec-1 knockout mice with a wild-type genetic background and a human apolipoprotein B transgenic background, and restoration of apolipoprotein B mRNA editing by somatic gene transfer of Apobec-1.

We have produced gene knockout mice by targeted disruption of the apobec-1 gene. As recently reported by Hirano et al. (Hirano, K.-I., Young, S. G., Farese, R. V., Jr., Ng, J., Sande, E., Warburton, C., Powell-Braxton, L. M., and Davidson, N. O. (1996) J. Biol. Chem. 271, 9887-9890), these animals do not edit apolipoprotein (apo) B mRNA or produce apoB-48. In this study we have performed a detailed analysis of the lipoprotein phenotypic effects of apobec-1 gene disruption that were not examined in the previous study. We first analyzed the plasma lipoproteins in knockout animals with a wild-type genetic background. Although there was no difference in plasma cholesterol between apobec-1(-/-), +/-, or +/+ mice, there was a marked (176%) increase in plasma apoB-100, from 1.8 +/- 1.2 mg/dl in apobec-1(+/+) mice to 2.7 +/- 0.6 mg/dl in apobec-1(+/-) and 5.0 +/- 1.4 mg/dl in apobec-1(-/-) mice. Plasma apoE was similar in these animals. By fast protein liquid chromatography (FPLC) analysis, there was a significant decrease in plasma high density lipoprotein (HDL) cholesterol in apobec-1(-/-) mice. We further fractionated the plasma lipoproteins into d < 1.006, 1.006-1.02, 1.02-1.05, 1.05-1.08, 1.08-1.10, and 1.10-1.21 g/ml classes, and found a marked (30-40%) reduction in the cholesterol and protein content in the (d 1.08-1.10 and 1.10-1.21) HDL fractions, corroborating the FPLC data. SDS-gel analysis revealed an absence of apoB-48, an increase in apoB-100 in the very low density lipoprotein (VLDL) and low density lipoprotein (LDL) fractions, and a small decrease in apoA-I in the HDL fractions in the apobec-1(-/-) samples. We next raised the basal plasma apoB levels in the apobec-1(-/-) animals by cross-breeding them with human apoB transgenic (TgB) mice. The plasma apoB-100 was 3-fold higher in apobec-1(-/-)/TgB+/- mice (26.6 +/- 18.3 mg/dl) than in apobec-1(+/+)/TgB+/- mice (9.8 +/- 3.9 mg/dl, p < 0.05). The apobec-1(-/-)/TgB+/- mice had a plasma cholesterol levels of 170 +/- 28 mg/dl and triglyceride levels of 106 +/- 31 mg/dl, which are 80% and 58% higher, respectively, than the corresponding values of 94 +/- 21 mg/dl and 67 +/- 11 mg/dl in apobec+/+/TgB+/- mice. By FPLC, the apobec-1(-/-)/TgB+/- animals developed markedly elevated plasma LDL cholesterol (518.5 +/- 329.5 microg/ml) that is 373% that of apobec1(+/+)/TgB+/- mice (139.0 +/- 87.0 microg/ml) (p < 0.05). The elevated plasma triglyceride was accounted for mainly by a 97% increase in VLDL triglyceride in the apobec1(-/-)/TgB+/- mice. We conclude that apobec-1(-/-) animals have a distinctive lipoprotein phenotype characterized by significant hyperapoB-100 and HDL deficiency in mice with a wild-type genetic background. Furthermore, the abolition of apoB mRNA editing elevates plasma total cholesterol and LDL cholesterol in apobec-1(-/-) animals with a TgB background. Finally, to exclude the possibility that absence of apoB mRNA editing was a secondary effect of chronic Apobec-1 deficiency, we treated apobec-1(-/-) mice with a replication-defective mouse Apobec-1 adenoviral vector and found that we could acutely restore apoB mRNA editing in the liver. These experiments indicate that Apobec-1 is an essential component of the apoB mRNA editing machinery and absence of editing in the knockout animals is a direct consequence of the absence of functional Apobec-1.

APOBEC-1 Deaminase↗
PubMed1996

Germ-line passage is required for establishment of methylation and expression patterns of imprinted but not of nonimprinted genes.

Embryonic stem (ES) cells homozygous for a disruption of the DNA (cytosine-5)-methyltransferase gene (Dnmt) proliferate normally with their DNA highly demethylated but die upon differentiation. Expression of the wild-type Dnmt cDNA in mutant male ES cells caused an increase in methylation of bulk DNA and of the Xist and Igf2 genes to normal levels, but did not restore the methylation of the imprinted genes H19 and Igf2r. These cells differentiated normally in vitro and contributed substantially to adult chimeras. While the Xist gene was not expressed in the remethylated male ES cells, no restoration of the normal expression profile was seen for H19, Igf2r, or Igf2. This indicates that ES cells can faithfully reestablish normal methylation and expression patterns of nonimprinted genes but lack the ability to restore those of imprinted genes. Full restoration of monoallelic methylation and expression was imposed on H19, Igf2, and Igf2r upon germ-line transmission. These results are consistent with the presence of distinct de novo DNA methyltransferase activities during oogenesis and spermatogenesis, which specifically recognize imprinted genes but are absent in the postimplantation embryo and in ES cells.

Alleles↗
PubMed1996

De novo DNA cytosine methyltransferase activities in mouse embryonic stem cells.

It has been a controversial issue as to how many DNA cytosine methyltransferase mammalian cells have and whether de novo methylation and maintenance methylation activities are encoded by a single gene or two different genes. To address these questions, we have generated a null mutation of the only known mammalian DNA methyltransferase gene through homologous recombination in mouse embryonic stem cells and found that the development of the homozygous embryos is arrested prior to the 8-somite stage. Surprisingly, the null mutant embryonic stem cells are viable and contain low but stable levels of methyl cytosine and methyltransferase activity, suggesting the existence of a second DNA methyltransferase in mammalian cells. Further studies indicate that de novo methylation activity is not impaired by the mutation as integrated provirus DNA in MoMuLV-infected homozygous embryonic stem cells become methylated at a similar rate as in wild-type cells. Differentiation of mutant cells results in further reduction of methyl cytosine levels, consistent with the de novo methylation activity being down regulated in differentiated cells. These results provide the first evidence that an independently encoded DNA methyltransferase is present in mammalian cells which is capable of de novo methylating cellular and viral DNA in vivo.

Animals↗
PubMed1996

[A comparison of plasma amino acid concentrations between appropriate and small for gestational age fetuses].

OBJECTIVE: To investigate the role of amino acid played in pathogenesis of small for gestational age (SGA) fetuses. METHODS: Plasma amino acids' concentrations (PAAC) of umbilical venous samples obtained by cordocentesis before labor or at cesarean section were measured in 30 cases of appropriate for gestational age (AGA) fetuses at different gestational age. PAAC of both mother and fetuses were measured and compared in 10 cases of SGA and 10 cases of AGA. RESULTS: In cases of AGA, the PAAC in fetuses (3.11 +/- 0.41 mmol/L) were found to be higher than that in mothers. There were significant correlations between fetal and maternal PAAC. The total PAAC in mothers and fetuses, and its ratios were not changed with gestational age. In cases of SGA, essential amino acids' concentration (EAA), especially branch chain amino acid (BCAA) and lysine, decreased significantly. The feto-maternal ratios of EAA and BCAA were reduced significantly, whereas concentrations of EAA and BCAA in mothers did not change significantly. CONCLUSIONS: The results indicated that placental function and maternal nutrient supplement were important factors for maintaining fetal growth and development. In AGA cases, relationship of PAAC between mothers and fetuses were kept in a stable balance. In SGA fetuses certain amino acid metabolic disturbances existed. The reduction of some PAAC was not due to their decrease in mothers.

Amino Acids, Branched-Chain↗
PubMed1996

[The in vitro antitumor responses of murine peritoneal macrophages induced by adenovirus-mediated IL-4 and/or M-CSF gene therapy].

OBJECTIVE: To observe the antitumor responses of murine peritoneal macrophages induced by adenovirus-mediated IL-4 and/or M-CSF gene transfer. METHODS: The IL-4 gene and/or M-CSF gene was transfected into murine peritoneal macrophages-mediated by adenovirus and the levels of IL-4, M-CSF, TNF, IL-1 and NO in the supernatant of the macrophages and the cytotoxicity of the macrophages to tumor cells were assayed. RESULTS: The high levels of IL-4 and M-CSF could be detected in the supernatant of macrophages 18 hours after being infected with advenovirus expressing IL-4 or M-CSF. The cytotoxicity of the macrophages engineered to secrete IL-4 or M-CSF increased significantly, and when IL-4 gene and M-CSF gene were cotransfected into the macrophages or the macrophages were co-stimulated with LPS, the cytotoxicity increased even more significantly. The levels of TNF, IL-land NO in the supernatant of macrophages also increased. CONCLUSION: The results demonstrated that transfection of IL-4 and/or M-CSF gene into macrophages could augment their anti-tumor immunity.

Adenoviruses, Human↗
PubMed1995

Developmental defects of the ventromedial hypothalamic nucleus and pituitary gonadotroph in the Ftz-F1 disrupted mice.

Ad4BP (or SF-1) has been identified as a transcription factor which regulates all the steroidogenic P450 genes in the peripheral organs, and is encoded by the mammalian homologue of Drosophila FTZ-F1 gene. mRNA coding for Ad4BP was detected in the hypothalamus and pituitary of rats by RT-PCR. Immunohistochemical analyses using an antiserum to Ad4BP in the brain and pituitary revealed that the transcription factor is expressed in nuclei of the dorsomedial part of the ventromedial hypothalamus (dmVMH) and in some subpopulation of the adenohypophysial cells. Double immunostaining of the pituitary for Ad4BP and trophic peptide hormones, FSH, TSH, and ACTH, indicated a restricted localization of Ad4BP to the gonadotroph. Disruption of the mouse Ftz-F1 gene was clarified to induce severe defects in the organization of the dmVMH and the function of the pituitary gonadotroph. However, some of the dm VMH neurons and pituitary gonadotrophs persisted, which provided a sharp contrast to complete agenesis of the peripheral steroidogenic tissues (adrenal and gonads) in the mutant mouse. Additional abnormalities were seen in the ventrolateral part of VMH and dorsomedial hypothalamic nucleus, both of which do not express Ad4BP but have strong reciprocal fiber-connections with the dmVMH. Aromatase P450-containing cells in the medial preoptico-amygdaloid region, which were devoid of Ad4BP, persisted even in the brain of the gene disrupted mice. The present results clearly showed that the hypothalamic and pituitary Ad4BPs are essential to normal development of the functional VMH and gonadotroph through some mechanism distinct from that in the peripheral steroidogenic tissues.

Animals↗
PubMed1995

Structural relationships between social support and coping.

Relationships between social support and coping were examined over a one-year period in a sample (n = 120) exposed to a specific stressor (i.e. a spinal cord injury). Two issues were evaluated: (1) patterns of social support and coping over time; and (2) the direction of the effects of coping on social support or vice versa. Subjects had incurred a spinal cord injury within the preceding year, completed their rehabilitation, and returned to the community. They were assessed at 1, 4 and 12 months post-discharge to capture possible changes in patterns of social support and coping. Covariance structure modelling indicated a single-factor construct based on three measured subscales for social support (instrumental/informational/emotional), and for coping (problem-oriented/perception-oriented/emotion-oriented). While the factor structure of coping was invariant over time, the structure of social support changed from a high concentration of informational support at one month to a higher saturation of emotional support at 4 and 12 months, potentially reflecting changes in the salience of different components of the network. The perceived availability of social support was seen to have direct effects on future coping. At one month, social support had a direct positive effect on coping at four months. However, at four months social support had a negative effect on coping at 12 months, which may reflect a change in the structure of the social support construct itself. That is, as the factor structure of social support varied with time, coping may also have been influenced by differing perception of one's needs and circumstances. Thus, the study provides evidence for the dynamic effects of social support on coping, depending on one's stage in the process of long-term adjustment. The findings underscore the interplay between social support and coping, and the need for future research and practical applications to recognize temporal effects on the relationships between these two complex constructs.

Activities of Daily Living↗
PubMed1995

Striking changes in the structure and organization of rat fetal membranes precede parturition.

Premature rupture of fetal membranes can harm infant and mother. It is unclear whether structural changes predispose these membranes to breaking. We thus assessed rat visceral yolk sac placenta (VYSP) and amnion by light and by transmission electron microscopy on Days 18-21 of gestation. Light microscope sections were stained for connective tissue (extracellular matrix) components: collagen, glycoprotein, and glycosaminoglycans/proteoglycans. Some tissue was incubated with chondroitinase ABC. We observed that fetal membranes became increasingly fragile, rupturing readily on Day 21. On Days 18-20, the two epithelial layers of the capsular VYSP were separated by a well-developed, well-vascularized connective tissue layer that stained intensely for all matrix components studied; on Day 21, the connective tissue layer was thinner, moderately stained, and less vascularized. On Days 18-20, the two cellular layers of the amnion were separated by a narrow, compact connective tissue layer that stained modestly for all matrix components; on Day 21, this area was widened and stained faintly. Transmission electron microscopy showed that collagen fibrils of the amnion were abundant, closely packed, and well organized on Days 18-20, whereas on Day 21 they were few in number, widely spaced, and disorganized. Similar changes were present after incubation with chondroitinase ABC. In addition, amniotic epithelial cells were moribund and delaminating, basal laminae were deteriorating or absent, and few cells were at the outer surface of the amnion. All changes preceded parturition. We conclude that the structural integrity of rat fetal membranes is impaired before birth through the loss of connective tissue components and cells, changes that presumably underlie membrane rupture. Lastly, the similarity of structural changes in rat and human fetal membranes point to the potential usefulness of the rat model.

Amnion↗
PubMed1995

92-kDa gelatinase (matrix metalloproteinase-9) is induced in rat amnion immediately prior to parturition.

The fetal membranes undergo striking changes in structure before delivery that involve catabolism of the extracellular matrix. To investigate the role of specific enzymes in this process, we examined gelatinase activities in rat amnion, visceral yolk sac placenta, and placenta and amniotic fluid between Days 18-21 of pregnancy. Matrix metalloproteinase (MMP)-2 was present in amnion on all days, and its activity increased slightly on Day 21. The 92-kDa gelatinase, MMP-9, was not detected on Days 18-20 but appeared by the morning of Day 21. There was a marked increase in MMP-9 mRNA in the amnion on Day 20, preceding the appearance of MMP-9 activity. Western blotting confirmed an increase in MMP-9 protein in amnion on Day 21. MMP-2 and MMP-9 activities were detected in extracts of whole yolk sac placenta, placenta, and amniotic fluid, but there were no striking changes in these gelatinases between Days 18 and 21. However, the capsular regions of the visceral yolk sac placentae, which thin and rupture during labor, did show higher MMP-9 activity on Day 21 than on Days 18 and 20. We suggest that the striking increase in MMP-9 expression in amnion and possibly the capsular region of the visceral yolk sac placenta approximately 12 h prior to delivery is responsible, in part, for the alterations in the structure of these fetal membranes before parturition.

Amnion↗
PubMed1995

92-kd type IV collagenase (matrix metalloproteinase-9) activity in human amniochorion increases with labor.

To determine whether specific collagenolytic enzymes are expressed in human fetal membranes with labor, we examined gelatinase activity in extracts of amniochorion by zymography. The 92-kd gelatinase (MMP-9) was barely detectable in extracts of fetal membranes before the onset of labor but was readily demonstrable in extracts prepared from membranes isolated from laboring women or membranes collected immediately after delivery. In contrast, the 72-kd gelatinase (MMP-2) was detectable in extracts from pre- and post-labor membranes. Ethylenediaminetetracetic acid and the tissue inhibitor of metalloproteinases, TIMP-1, inhibited the gelatinase activities detected by zymography, confirming that the enzymes are metalloproteinase. Assay of amniochorion gelatinase activity using a radiolabeled denatured collagen substrate revealed a more than twofold increase in activity comparing pre-labor with post-labor fetal membrane extracts. A function-blocking anti-MMP-9 monoclonal antibody inhibited pre-labor membrane gelatinase activity by approximately 11.5%, which was only slightly greater inhibition than observed with irrelevant monoclonal antibodies. However, post-labor membrane gelatinase activity was reduced by 53% by the function-blocking antibody, indicating that MMP-9 is a major contributor to the increased gelatinase activity extractable from post-labor membranes. Western blot analyses demonstrated increased MMP-9 protein in amniochorion extracts after onset of labor. MMP-9 protein and mRNA were co-localized in amnion epithelium, underlying macrophages and chorion laeve trophoblast and decidual cells after labor. We conclude that 1) MMP-9 activity and protein in human amniochorion increases with labor and 2) MMP-9 is expressed by amnion epithelium, macrophages and chorion laeve trophoblast and decidual cells. The increased expression of MMP-9 may result in degradation of the extracellular matrix of the fetal membranes and facilitate their rupture under both physiological and pathological conditions.

Amino Acid Sequence↗