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At least 217 records · Page 12Linked to original sources
PubMed1986

Epithelial regulation of prolactin effect on amnionic permeability.

The permeability of human amnion to tritiated water is reduced in the presence of both human and ovine prolactin. The cellular composition of amnion is such that the action of prolactin on this membrane probably occurs by way of the epithelium lining the fetal surface. The present study sought to confirm an epithelial site of action of prolactin on the permeability of amnionic membrane to tritiated water. In addition, radioautography and competition experiments were conducted to determine a possible receptor-mediated mechanism for prolactin action. Membrane permeability to tritiated water was found to be equivalent for both intact membranes and membranes enzymatically stripped of the lining epithelial cells. However, when ovine prolactin was presented to the fetal surface of amnion, only intact membrane displayed decreased permeability to tritiated water. Although localization of iodine 125-labeled prolactin to the light cell population of amniotic epithelium was observed, positive evidence of a receptor-mediated mechanism could not be established. The results indicate that the permeability of human amnion to water is influenced principally by cells of the epithelium in response to prolactin.

Autoradiography↗
PubMed2000

Validation of radiation sterilization dose for lyophilized amnion and bone grafts.

A limited number of grafts produced in one batch is the main constrain to validate radiation sterilization dose of amnion and bone grafts according to ISO standard. The validation experiments done were according to ISO 13409 with a slight modification in sampling method. The experiments were carried out three times by using 20 samples each, 10 for bio-burden enumeration and 10 for sterility test at verification dose. The average bio-burden with sample item portion (SIP) = 1 for amnion membranes were 98, 50 and 69 cfu respectively and 0 cfu for bone grafts. Verification dose experiments, were done at doses of 2.90 kGy for bone grafts and 5.13 kGy for amnion grafts and the results of sterility tests showed that amnion grafts got one positive and bone grafts got 0 positive. The results met the requirements of ISO 13409 so that the radiation sterilization dose, at sterility assurance level of 10(-6) was 25 kGy for both amnion and bone grafts. Viral contamination was excluded in this experiment.

Journal Article↗
PubMed1993

Brain natriuretic peptide is present in the human amniotic fluid and is secreted from amnion cells.

The presence and biochemical characteristics of human brain natriuretic peptide (hBNP) in the amniotic fluid at various gestational ages were investigated. The hBNP-like immunoreactivity (hBNP-LI) levels in amniotic fluid, determined by RIA, were 118.7 +/- 57.6 pmol/L (mean +/- SEM; n = 5) and 107.7 +/- 8.7 pmol/L (n = 9) in the first and second trimesters of pregnancy, respectively; it was significantly decreased to 28.4 +/- 5.1 pmol/L (n = 9) in the third trimester. However, human atrial natriuretic peptide-like immunoreactivity (hANP-LI) was not detected (< 0.3 pmol/L) in any of these samples. Northern blot analysis demonstrated hBNP mRNA in human amnion tissue. Moreover, cultured amnion cells secreted a significant amount of hBNP-LI (100-200 fmol/10(6) cells/day), but not hANP-LI, into the culture medium. The synthesis of hBNP in cultured amnion cells was further confirmed using the polymerase chain reaction. High performance gel permeation chromatography of hBNP-LI extracted from human amniotic fluid and the culture medium of amnion cells revealed that the predominant molecular form of hBNP-LI in both samples was the hBNP precursor, with an approximate mol wt of 12 kilodaltons. These findings indicate that hBNP is present in the human amniotic fluid, and that amnion cells synthesize hBNP and secrete it into the amniotic cavity.

Amniotic Fluid↗
PubMed1986

Amnionic fluid volume in prolonged pregnancy.

The evidence implicating reduced amnionic fluid volume as a major problem in prolonged pregnancy seems clear. Oligohydramnios serves to explain the association of umbilical cord compression fetal heart rate patterns in labors complicated by fetal distress and such cord entrapment may even explain the release of meconium into the amnionic fluid. Ultrasonic assessment of amnionic fluid volume, regardless of the definition of oligohydramnios used, appears to single out the prolonged pregnancy where the fetus is at risk. Important questions remain as to how best to quantify fluid volume using sonography and, importantly, whether normal amnionic fluid volume reliably predicts fetal well being for a predictable period of time. That is, oligohydramnios diagnosed using ultrasound seems meaningful, but whether a normal fluid volume permits safe expectant management needs further evaluation. This is particularly relevant if the liquor volume may subside within 24 to 48 hours as reported by Beischer et al. Unfortunately, the mechanisms by which amnionic fluid volume decreases in prolonged pregnancies remain unknown. As in Ballantyne's time, we still do not know ". . . what functions the fetus is performing during these accessory weeks . . . nor how he is performing them . . . ." But we have learned that oligohydramnios has a central role in producing some of the fetal complications associated with prolonged pregnancy.

Amniotic Fluid↗
PubMed1982

[Enzymic determination of dipalmitoylphosphatidylcholine in human amnionic fluid--its application for the judgement of fetal lung maturity before birth (author's transl)].

Respiratory distress syndrome (RDS) is believed to be caused by a deficiency of pulmonary surfactant. The surfactant, secreted by fetal lung into amnionic fluid, has been analyzed by a variety of methods, but none of these methods have been found accurate enough to be widely used. Dipalmitoylphosphatidylcholine (DP-PC), the major surface-active component of the surfactant, occupies more than 50% of the surfactant phospholipids. In this study, DP-PC isolated from amnionic fluid, was determined enzymatically. DP-PC started to increase gradually in amnionic fluid from 22nd week of gestation, showed rather rapid increase after 35th week of pregnancy, and reached to a value of 6.97 +/- 0.56 mg/dl (Mean +/- SEM, n = 117) between 38 and 42nd week of gestation. This increase of DP-PC during gestation was found to be quite similar to that of L/S ratio reported previously. Eight out of 10 infants with RDS had less than 1.0 mg/dl of DP-PC in the amnionic fluid, whereas 137 infants without any sign of RDS had more than 1.0 mg/dl of DP-PC except 5 cases. These results demonstrated that if more than 1.0 mg/dl of DP-PC was found in amnionic fluid before birth, the fetus could be judged to have mature lung with 96% accuracy. In addition the enzymic determination of DP-PC requires less time, rather easy and reliable method to be done in most general clinical laboratories with less cost. Therefore we believe this method will be widely used in near future for the detection of RDS before birth.

Amniotic Fluid↗
PubMed2006

Evaluation of the cranial base in amnion rupture sequence involving the anterior neural tube: implications regarding recurrence risk.

BACKGROUND: Amniotic bands can cause disruption of the cranial end of the developing fetus, leading in some cases to a neural tube closure defect. Although recurrence for unaffected parents of an affected child with a defect in which the neural tube closed normally but was subsequently disrupted by amniotic bands is negligible; for a primary defect in closure of the neural tube to which amnion has subsequently adhered, recurrence risk is 1.7%. In that primary defects of neural tube closure are characterized by typical abnormalities of the base of the skull, evaluation of the cranial base in such fetuses provides an approach for making a distinction between these 2 mechanisms. This distinction has implications regarding recurrence risk. METHODS: The skull base of 2 fetuses with amnion rupture sequence involving the cranial end of the neural tube were compared to that of 1 fetus with anencephaly as well as that of a structurally normal fetus. The skulls were cleaned, fixed in 10% formalin, recleaned, and then exposed to 10% KOH solution. After washing and recleaning, the skulls were exposed to hydrogen peroxide for bleaching and photography. RESULTS: Despite involvement of the anterior neural tube in both fetuses with amnion rupture sequence, in Case 3 the cranial base was normal while in Case 4 the cranial base was similar to that seen in anencephaly. CONCLUSIONS: This technique provides a method for determining the developmental pathogenesis of anterior neural tube defects in cases of amnion rupture sequence. As such, it provides information that can be used to counsel parents of affected children with respect to recurrence risk.

Amnion↗
PubMed1989

The effect of gamma irradiation on injectable human amnion collagen.

The effect of gamma irradiation on the physicochemical properties of injectable human amnion collagen was investigated. Pepsin-extracted human amnion collagen was purified, reconstituted, and irradiated with varying doses of gamma irradiation (0.25 Mrads to 2.5 Mrads). Gamma irradiation had a significant impact on the physical characteristics of the collagen. The neutral solubility of collagen in PBS at 45 degrees C was decreased from 100% for the nonirradiated control sample to 16% for the 2.5 Mrads irradiated sample. SDS polyacrylamide gel electrophoresis also demonstrated the dose-dependent effect of gamma irradiation on collagen cross-links. Electron microscopic observation revealed that even at low irradiation dose (0.25 Mrads), collagen fibril diameter increased. The average diameter was 50 nm for nonirradiated control fibrils, while 4.4 percent of the irradiated collagen fibrils had a diameter greater than 100 nm. Irradiated collagen showed little evidence of damage. Well-preserved cross-striations were found in collagen fibrils at all doses of irradiation. Native amnion collagen irradiated with gamma rays demonstrated a slight increase in resistance to collagenase degradation compared with nonirradiated native collagen samples. Increased resistance to collagenase did not correlate with increasing irradiation dose. After 30 min of incubation at 37 degrees C, both irradiated and nonirradiated collagen was completely digested by collagenase. However, gamma-irradiated collagen did become more sensitive to hydrolysis by trypsin. The higher the irradiation doses used, the greater sensitivity to trypsin was observed. At 0.25 Mrads irradiation only a slight increase was found. No marked differences in amino acid composition were noted among the high dose irradiated, low dose irradiated and control amnion collagen.

Amino Acids↗
PubMed1984

An acellular human amnionic membrane model for in vitro culture of type II pneumocytes: the role of the basement membrane in cell morphology and function.

To determine whether a preformed basement membrane contributes to the maintenance of morphology and function of type II pneumocytes, we cultured isolated adult rat type II pneumocytes on the basement membrane and stromal surfaces of an acellular human amnionic membrane and on plastic. The presence of lamellar bodies on transmission electron microscopy and epithelial morphology in culture and a characteristic phospholipid profile after incubation with 3H-acetate identified the cells as type II. When type II cells were cultured on a preexisting basement membrane, they formed a well-organized monolayer with polarity, centrally located surface microvilli, and more basally located nuclei. Individual cells maintained a cuboidal morphology for 8-10 days. Intracellularly, there were numerous mitochondria, endoplasmic reticulum (ER), and lamellar bodies. The cells secreted a new basal lamina of their own. When cultured on the stromal side of the amnion, the cells became flattened within 48-60 hours, formed small lamellar bodies, and had scanty surface microvilli; they formed clumps and appeared less ordered. These cells did not secrete a visible basement membrane, and the majority detached from the stromal surface after 7-8 days in culture. In addition, culture on the basement membrane aspect of the amnion prevented the rapid decline in the percentage of 3H-acetate label incorporated in phosphatidylcholine after 72 hours of culture. We conclude that a preformed basement membrane influences the function and morphology of type II pneumocytes, organizes them into a monolayer in culture, and influences deposition of a visible basal lamina. Thus, the acellular human amnion provides an excellent model for the systematic study of basement membrane influence on the biology and pathology of these cells.

Amnion↗
PubMed2001

Amnion rupture sequence in a first trimester missed abortion.

We report the diagnosis of amnion rupture sequence made by sonography and fetoscopy during the first trimester of gestation in a case of missed abortion. The investigation revealed a demised fetus with the characteristics of 9 weeks of development. The early fetus had an amnion adhesion at the tip of the nose and strands of amnion wrapped around the terminal phalanges of both feet. No defects in addition to the face and limb involvement were identified. The karyotype was normal: 46,XX. In the reported case, fetoscopy allowed confirmation of the sonographic diagnosis of an amnion rupture sequence in the first trimester of gestation and consequently helped to clarify the cause of abortion in this case of early fetal demise.

Abortion, Missed↗
PubMed1995

Ultrasound observation of amnion dysmorphism at 14.5-16 weeks.

The presence of chorio-amniotic separation and amnion anomalies was recorded in 9500 patients referred for vaginal ultrasound examination at 14.5-16 weeks' gestation. In all patients with a change in the amnion, a search for fetal anomalies was performed and pregnancy outcome was checked. Amnion dysmorphism was observed in 30 cases. The main findings were a floating membrane which changed its configuration when the uterus was tilted and multiple intrauterine amniotic sheets. In no case was attachment of the fetus to the membranes noted. There was no fetal abnormality and pregnancy outcome was favourable in all patients. In conclusion, ultrasound visualization of amnion dysmorphism in early pregnancy is not associated with an adverse pregnancy outcome.

Amnion↗
PubMed1994

Implication of mRNA binding proteins in the regulation of cyclo-oxygenase in human amnion at term.

The onset of labour is associated with an increase in prostaglandin synthesis in amnion which appears to be mediated at least in part by an increase in cyclo-oxygenase (COX) expression. We have tested the hypothesis that COX expression is controlled in amnion by the binding of a protein to the COX mRNA which may inhibits its translation, as has been seen in vascular smooth muscle cells. Using differential RNA extraction protocols which extract either total mRNA or only mRNA which is not protein bound, we have found that, in amnion, the increase in COX-2 expression seen after the onset of labour is entirely in the protein bound fraction. Unlike in vascular smooth muscle, increased expression of COX-2 in amnion cells is therefore associated with increased rather than decreased protein binding to the mRNA. This protein may be involved in translation initiation or elongation or in mRNA stability. There does not appear to be a protein bound COX-1 mRNA fraction.

Amnion↗
PubMed2007

Validation and substantiation of 25 kGy as sterilization dose for lyophilized human amnion membrane.

The validation and substantiation of sterilization dose for lyophilized human amnion membrane by gamma irradiation delivered by Co60 source were investigated. The validation experiments were conducted according to ISO 13409 method B. A total of 120 human amnion membranes were collected. Of these, 10 membranes were used for estimation of bioburden and 20 membranes were used for the individual sterility test at verification dose. The average bioburden per product unit with sample item portion (SIP = 1) for lyophilized human amnion membrane was 572 cfu. The verification dose experiments were done at dose of 8.1 kGy and the results of sterility tests showed that human amnion membrane got one positive. Consequently, the sterilization dose of 25 kGy was confirmed and substantiated.

Amnion↗
PubMed1985

Relation between cyclic adenosine monophosphate and prostaglandin output by dispersed cells from human amnion and decidua.

We have examined the ability of activators of adenylate cyclase and cyclic adenosine monophosphate to affect the output of prostaglandins E and F by dispersed cells of amnion and decidua collected from women following spontaneous labor. Cyclic adenosine monophosphate production by amnion and decidua cells was stimulated in a dose-dependent fashion by cholera toxin and by forskolin in the absence or presence of the phosphodiesterase inhibitor 3-isobutyl-1-methyl xanthine. Forskolin and cholera toxin also stimulated prostaglandin E and F output from amnion and decidua cells. Similar effects were seen with cells incubated with dibutyryl cyclic adenosine monophosphate +/- 3-isobutyl-1-methyl xanthine. The beta-adrenergic receptor agonists salbutamol, isoproterenol, and epinephrine all stimulated prostaglandin E and F output from dispersed cells of both tissues. The stimulatory effect of 3-isobutyl-1-methyl xanthine was partially additive with the Ca2+ ionophore A23187. Basal outputs of prostaglandin and outputs stimulated by A23187 and by N6, O2'-dibutyryl adenosine 3':5'-cyclic monophosphate were attenuated by the calmodulin antagonist trifluoperazine in a dose-dependent fashion. We conclude that mechanisms exist for stimulation of adenylate cyclase in human amnion and decidua resulting in enhanced prostaglandin output. This pathway requires basal interaction with Ca2+-calmodulin and may be additive with cyclic adenosine monophosphate-independent mechanisms for prostaglandin stimulation.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Vascularization of the ovine amnion and chorion: a morphometric characterization of the surface area of the intramembranous pathway.

OBJECTIVE: The purpose of this study was to characterize the vascularization of the ovine amnion, allantois, and chorion. STUDY DESIGN: A white silicone vascular casting material was infused into both umbilical arteries of nine fetal sheep ranging in age from 58 to 142 days' gestation. A morphometric analysis of photomicrographs of the membranes was then performed with computerized image analysis techniques. RESULTS: After removal of the uterus, the fetus was surrounded by a layer of white silicone-filled microvessels in the chorion. The amniotic membrane after separation from the chorion was covered by a fine mesh of microvessels, whereas the allantois was avascular. The amniotic membrane readily separated into an outer vascularized layer and an inner, avascular layer containing the amnion. Approximately 50% of the surface of the chorionic membrane was covered by microvessels; this appeared independent of gestational age. At midgestation 30% of the surface of the amnion was covered by microvessels, and this decreased to 17% at 142 days. Relative to fetal weight, the amniotic and chorionic vascular surface areas decreased from 6 to 0.3 and from 15 to 1.5 cm2/gm fetal weight, respectively, over the last half of gestation. CONCLUSIONS: There is an extensive network of microscopic fetal blood vessels within the ovine chorion and covering the outer surface of the amnion. These vessels appear to be ideally situated to facilitate a direct exchange of water and solutes between amniotic or allantoic fluids and fetal blood through the intramembranous pathway.

Allantois↗
PubMed1991

Amnion inversion in the treatment of giant omphalocele.

Operative repair of giant omphaloceles remains a technical challenge to close the wide abdominal wall defect. Currently, most surgeons remove the amnion to approximate the linea alba and/or skin edges or to suture prosthetic material to the abdominal wall and cover the defect with skin flaps. In doing so, the liver commonly becomes extruded and distended with blood, compounding the problem of reducing all of the viscera within the small abdominal cavity. Furthermore, bowel obstruction from adhesions produced from opening the abdomen is a life-long threat. We describe six cases of giant omphalocele in which the amnion was left intact, and it was progressively inverted into the abdominal cavity by using the silastic silo, as it is used for gastroschisis. The birth weight of these infants ranged from 2,360 to 3,240 g. The abdominal wall defect measured 7.0 cm to 10.5 cm in width, and protruded at least 8 cm beyond the abdominal wall. The first stage of repair was to suture the silastic silo to the skin-amnion junction, and progressively reduce the bowel and liver within the abdomen. The intrabdominal pressure is monitored by nasogastric tube or by an indwelling bladder catheter to avoid pressures greater than 20 cm H2O, which might compromise intestinal and renal circulation. The second stage consisted of incising the skin/amnion junction to expose the linea alba. The linea alba was approximated while leaving the amnion intact and folding it into the abdominal cavity. This avoids entering the peritoneum or interfering with the blood flow to and from the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1984

Androgen binding in human fetal amnion.

Human fetal amnion cytosol obtained at term is able to bind specifically [3H]testosterone. The cytosol (105,000 g supernatant) from human amnion was used after a 30 min treatment with dextran-coated charcoal and incubated with increasing concentrations of [3H]testosterone, [3H]dihydrotestosterone, [3H]methyltrienolone for 2 h at 4 degrees C and for 16 h at 15 degrees C. To avoid any possible contamination of sex hormone binding globulin we used a Sepharose 4B column. Scatchard plot analysis of the data after incubation at 4 degrees C for 2 h showed that the amnion possesses high affinity (Kd = 0.62 +/- 0.20 nM) and low capacity (95.0 +/- 21.1 fmol/mg protein) binding sites for [3H]testosterone. After incubation at 15 degrees C for 16 h, we obtained a high affinity (Kd = 0.29 +/- 0.14 nM), low capacity (49.5 +/- 12.8 fmol/mg protein) and a low affinity (Kd = 5.55 +/- 2.55 nM), high capacity (181.7 +/- 20.8 fmol/mg protein) binding sites for [3H]testosterone. The values of Kd, calculated from Scatchard plot analysis were 1.03 +/- 0.7 nM with 20.2 +/- 10.4 fmol/mg protein and 1.97 +/- 1.06 nM with 55.6 +/- 15.9 fmol/mg protein for [3H]methyltrienolone and [3H]dihydrotestosterone respectively. These findings suggest that human fetal amnion cytosol at term contains a specific binding protein for androgens.

Amnion↗
PubMed1981

The Production of beta 1-specific pregnancy glycoprotein (SP1) by the amnion.

Using indirect immunofluorescence, beta 1-specific pregnancy glycoprotein (SP1) was localised to the amnion cells, as well as to trophoblastic cells. Cultures of fragments of amnion incubated with 3H-leucine for up to 72 h demonstrated that protein was synthesized by the amnion. Using antisera specific to SP1 it was shown that after 72 h incubation about 50% of the total protein could be precipitated. These studies demonstrate that the amnion cells are actively involved in the synthesis of SP1 and could account for the high level of this glycoprotein in amniotic fluid.

Amnion↗
PubMed1983

Comparative study of the human amnion, chorion and chorioamnion permeability to monovalent cations.

Amnion, chorion and chorioamnion from human term placenta were mounted between two Ussing chambers. The monovalent cation transfer was estimated by potentials (dilution, bi-ionic) and conductance measurements. This study revealed that amnion and chorioamnion discriminate the monovalent cations (the sequence is: Rb = Cs = K greater than Na greater than Li), while the chorion does not discriminate these cations. This discrimination relies on the size of the sites on the cell membrane and in intercellular spaces. The monovalent cation conductance for the three layers is gA greater than gC = gCA, and reveals that the chorioamnion properties derive in part from the properties of the isolated amnion (cationic discrimination) and those of the isolated amnion + chorion (size of sites and hydration pathways). The transfer is dependent on the three membranes' orientation and corresponds to fetal needs; the conductance ratio (g mother-fetus/g fetus-mother) is always superior to 1 when the two sides are bathed by the same medium.

Amnion↗