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PubMed2006

[Clinical study on application of bovine amnion on burn wounds].

OBJECTIVE: To observe clinical effects of burn wounds treatment with bovine amnion and to screen the best method of preparing and storing of bovine amnion. METHODS: From January 2004 to January 2005. We selected randomly 58 patients with superficial secondary wound, deep secondary wound, autografting area for removal of eschars and tangential excision, fetching skin area or residual burn wound . Using auto-control, every burn wound was divided into 3 parts and was treated with 3 dressings: bovine amnion dealt with by 0.1% chlorhexidine (group A), bovine amnion dealt with by 0.4% glutaraldehyde (group B) and vaseline gauze dressing (group C as control). The clinical effects were compared between different groups and the method of preparing and storing bovine amnion was evaluated. RESULTS: The dressing texture of group A was softer than that of group B, and its flexibility was fine. The pre-treatment was not necessary for dressing in group A. When the dressing was used on burn wounds in groups A and B, pain was slight, but pain was obvious in group C; healing time in groups A and B was much less than that in group C, showing statistically significant difference (P<0.01). There was no statistically significant difference in healing time between groups A and B (P>0.05). The infection ratio of burn wound in deep secondary wound and residual burn wound of groups A and B is much lower than that of group C, showing statistically significant difference (P<0.05); in the other burn wounds there was no significant difference (P>0.05). There was no statistically significant difference between groups A and B (P> 0.05). CONCLUSION: Bovine amnion could make benefit on burn wounds healing, reduce infection ratio of burn wounds, could be used on different kinds of burn wounds. The clinical effect between bovine amnion dealt with by glutaraldehyde and by chlorhexidine is similar. Whereas the latter is more easy to be popularized.

Adolescent↗
PubMed1989

Immune response to gamma-irradiated injectable human amnion and human skin collagens in the rat.

The immune response in rats to gamma-irradiated human amnion and human skin collagen was characterized through histologic and immunologic methods. Pepsin-extracted human amnion collagen and skin collagen were purified and reconstituted. Implants of amnion collagen demonstrated greater persistence than skin collagen. For amnion collagen implants, no significant inflammatory response was found. Fibroblast and adipocyte ingrowth and neovascularization were present. Conversely, obvious inflammatory infiltration was evident in the skin collagen implants. Enzyme-linked immunosorbent assay results showed that anti-amnion collagen antibody levels were significantly lower than anti-skin collagen antibody levels against their respective implant materials. The ratios of type I to type III collagen are 56:44 and 95:5 for amnion collagen and skin collagen, respectively. These findings suggest that in this heterologous type system, type III collagen-rich amnion collagen preparations appear superior to skin collagen for soft-tissue augmentation.

Amnion↗
PubMed1988

Epidermal growth factor stimulation of prostaglandin E2 biosynthesis in amnion cells. Induction of prostaglandin H2 synthase.

Amnion is believed to be a tissue of signal importance, anatomically and functionally, in the maintenance of pregnancy and during the initiation of parturition. Epidermal growth factor (EGF)-like agents cause a striking increase in the secretion of prostaglandin E2 (PGE2) in human amnion cells but only if arachidonic acid is present in the culture medium. To investigate the regulation of arachidonic acid metabolism by EGF-like agents in amnion, we used mEGF and human amnion cells in primary monolayer culture as a model system. The amount of PGE2 secreted into the culture medium was quantified by radioimmunoassay and the rate of conversion of [14C]arachidonic acid to [14C]PGE2 (PGH2 synthase activity) in cell sonicates was determined under optimal in vitro conditions. Treatment of amnion cells with mEGF led to a marked increase in the rate of production of PGE2. The specific activity of PGH2 synthase (viz. the combined activities of prostaglandin endoperoxide (PGH2) synthase and PGH2-PGE isomerase) was increased by 2-5-fold in cells treated with mEGF. Treatment of amnion cells with mEGF for 4 h did not affect the specific activities of phospholipase A2 or phosphatidylinositol-specific phospholipase C. By immunoisolation of newly synthesized, [35S]methionine-labeled PGH2 synthase, we found that mEGF stimulated de novo synthesis of the enzyme. Thus, mEGF acts in human amnion cells in primary monolayer culture to increase the rate of PGE2 biosynthesis by a mechanism that involves induction of PGH2 synthase; the manifestation of EGF action on PGE2 biosynthesis is dependent on the presence of nonesterified arachidonic acid.

Amnion↗
PubMed1980

Initiation of human parturition. XI. Lysosomal enzyme release in vitro from amnions obtained from laboring and nonlaboring women.

In the present investigation, we sought to ascertain whether an alteration in the physiology of amnionic lysosomes could be demonstrated in association with normal human labor at term. We reasoned that perturbation of the lysosomes of amnion would be associated with a greater rate of release of known lysosomal marker enzyme activity from this tissue. In order to investigate this possibility, we employed discs of amnion tissue which were incubated in medium containing sucrose (0.25M). We observed that the rate of release of lysosomal marker enzyme activity, N-acetyl glucosaminidase, into the incubation medium from amnion tissue obtained from laboring women was greater than the rate of release of the same enzyme activity from amnion tissue obtained from women who were not in labor. During incubation, there was no detectable release of lactate dehydrogenase, a cytosolic marker enzyme, which attests to the viability of the amnion tissue during the experiment. These findings are consistent with the view that there is an alteration in the physiology of lysosomes of the amnion associated with human labor at term, a finding which is supportive of a role for lysosomes of the human fetal membranes in the initiation of human parturition.

Acetylglucosaminidase↗
PubMed2002

Extracellular matrix of human amnion manufactured into tubes as conduits for peripheral nerve regeneration.

The human amnion consists of the epithelial cell layer and underlying connective tissue. After removing the epithelial cells, the resulting acellular connective tissue matrix was manufactured into thin dry sheets called amnion matrix sheets. The sheets were further processed into tubes, amnion matrix tubes (AMTs), of varying diameters, with the walls of varying numbers of amnion matrix sheets with or without a gelatin coating. The AMTs were implanted into rat sciatic nerves. Regenerating nerves extended in bundles through tubes of 1-2 mm in diameter and further elongated into host distal nerves 1-3 weeks after implantation. Morphometrical analysis of the regenerated nerve cable at the middle of each amnion matrix tube 3 weeks after implantation was performed. The average numbers of myelinated axons were almost the same (ca. 80-112/10(4) microm(2)) in AMTs of 1-2 mm in diameter, as in the normal sciatic nerve (ca. 95/10(4) microm(2)). No myelinated fibers were found in AMTs composed of multiple thin tubes of 0.2 mm in diameter. The myelinated axons were thinner in implanted tubes than those in the normal sciatic nerve. The rate of occurrences of myelinated axons less than 4 microm in diameter was significantly higher in the AMTs, whereas axons in the normal sciatic nerve were diverse in distribution, with the highest population at 8-12 microm in diameter. Reinnervation to the gastrocnemius muscle was demonstrated electrophysiologically 9 months after implantation. It was concluded that the extracellular matrix sheet from the human amnion is an effective conduit material for peripheral nerve regeneration.

Amnion↗
PubMed1994

Human amnion collagen for soft tissue augmentation--biochemical characterizations and animal observations.

As bovine collagen is currently being scrutinized as to its immunogenicity in clinical use, a human source collagen, human amnion collagen (HAC), has been developed in our laboratory as an injectable biomaterial for soft tissue augmentation. Pepsin-extracted human amnion collagen was highly purified and reconstituted. Gamma irradiation was employed to ensure complete sterility and to produce cross-linking in collagen chains to improve implant persistence without the use of chemical additives. The purity and characteristics of human amnion collagen were proven by amino acid assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immune blotting, and collagenase digestion. Animal studies comparing both irradiated and nonirradiated amnion collagen to bovine collagen (Zyderm and Zyplast) were carried out in a rat model. Humoral immunity was evaluated by examining the sera for antibody reactivity towards the implanted human collagen by the ELISA test. Insignificant antibody levels against human amnion collagen were found. Animal observation revealed fibroplasia, vascular infiltration, and the development of adipocytes with the implant as well as a lack of inflammatory response following up to 12 months of implantation. The persistence rate of our human amnion collagen was equal to, or even longer than, that of both types of bovine collagen implants.

Amino Acids↗
PubMed2002

Origin of amnion and implications for evaluation of the fetal genotype in cases of mosaicism.

OBJECTIVE: To investigate presence of trisomy in amniotic epithelium (uncultured amnion) and mesenchyme (cultured amnion) from mosaic cases to understand the origins of these tissues and their relationship to pregnancy outcome. METHODS: Polymerase chain reaction (PCR) of microsatellite loci was used to determine the presence of trisomy (of meiotic origin only) in amnion samples from 33 placentas previously ascertained because of a prenatal diagnosis of trisomy mosaicism that was predominantly confined to the placental tissues. RESULTS: In 16 (48%) of 33 cases, trisomy was confirmed to be present by molecular analysis of uncultured amnion. In contrast, cytogenetic analysis of cultured amnion showed trisomy in only 2 of 20 informative cases. The molecular detection of trisomy in amnion was strongly associated with poor pregnancy outcome (intrauterine growth restriction, fetal anomalies and/or intrauterine/neonatal death) even when analysis was limited to cases negative for the trisomy on amniotic fluid (N = 22, p = 0.0005). CONCLUSIONS: We infer that amniotic mesenchyme (usually diploid) derives from early embryonic mesoderm of the primitive streak and not from the hypoblast as is commonly cited. Trisomy in amniotic epithelium suggests that high numbers of abnormal cells were present in the epiblast, and this correlates with poor outcome even when the subsequently derived fetus and amniotic mesenchyme appear to carry only diploid cells.

Abnormalities, Multiple↗
PubMed2003

Protective effect of Astragali radix extract on interleukin 1beta-induced in fl ammation in human amnion.

The aim of this study was to investigate the effect of Astragali radix extract on interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha production and prostaglandin E(2) (PGE(2)) and leukotriene C(4) (LTC(4)) release from IL-1beta-stimulated human amnion. Primary monolayer cultures of amnion cells were established from women undergoing elective caesarean section before the onset of labour. Production of both IL-6 and TNF-alpha was stimulated in a concentration-dependent manner by proinflammatory cytokine IL-1beta (0.01-10 ng/mL). Astragalus extract inhibited IL-6 production by approximately 75% from cells under IL-1beta-stimulated conditions. Treatment of amnion cells with IL-1beta (0.01-10 ng/mL) resulted in a significant increase in PGE(2) release. Incubation of the cells with the extract for 24 h significantly inhibited IL-1beta-induced PGE(2) production. A concentration-dependent increase in LTC(4) production by amnion cells occurred in response to IL-1beta. Astragalus extract blocked the effect of IL-1beta in LTC(4) production in human amnion. These results indicate that Astragali radix has a broad antiinflammatory effect in human amnion and may be considered a promising agent to protect preterm labour.

Amnion↗
PubMed1983

Source of prostaglandin precursor in human fetal membranes: arachidonic acid content of amnion and chorion laeve in diamnionic-dichorionic twin placentas.

The lipids of the avascular human amnion and chorion laeve are known to be enriched in the essential fatty acid arachidonic acid, the obligate precursor of prostaglandins of the 2-series. The present investigation was conducted to evaluate the source of arachidonic acid that is present in human fetal membranes. To do so we determined the arachidonic acid content of the lipid fractions of amnion and chorion laeve tissues from diamnionic-dichorionic twin placentas. We found that the arachidonic acid content of amnion from twin placentas was similar to that of amnion from singleton placentas irrespective of the site of amnion sampling. However, the same was not true of chorion laeve of diamnionic-dichorionic twin placentas. The arachidonic acid content of chorion laeve that was contiguous to the chorion laeve of its twin was strikingly reduced compared to that of chorion laeve contiguous to decidua vera obtained from either singleton or twin placentas. We conclude that the arachidonic acid in amnion is derived primarily from essential fatty acids in the amniotic fluid. However, the arachidonic acid in chorion laeve may be derived from essential fatty acid in the amniotic fluid as well as in maternal plasma by way of the decidua vera.

Amnion↗
PubMed1986

Response of human amnion cells in culture to 1,25-dihydroxycholecalciferol: increased 25-hydroxycholecalciferol 24-hydroxylase activity and prostaglandin E2 formation.

We investigated the possibility that 1,25-dihydroxycholecalciferol acts in human amnion as a physiologic calcium ionophore to effect increased prostaglandin E2 production in this tissue. This possibility was based on the propositions that this metabolite of vitamin D3 acts in other target tissues, that is, bone, intestine, chorioallantoic membrane, kidney, and intestine, to effect increased calcium absorption, that 1,25-dihydroxycholecalciferol is present in amniotic fluid, which bathes the amnion, and that the mobilization of calcium in amnion is associated with stimulation of enzymes, namely, phospholipase A2 and phosphatidylinositol-specific phospholipase C that act ultimately to effect the release of arachidonic acid, which in turn leads to increased prostaglandin E2 production. We found that human amnion cells, maintained in primary monolayer culture, are responsive to 1,25-dihydroxycholecalciferol. Treatment of these cells with 1,25-dihydroxycholecalciferol for 18 hours brought about the induction, in a dose-dependent manner, of 25-hydroxycholecalciferol 24-hydroxylase, a marker of 1,25-dihydroxycholecalciferol action. In addition, treatment of human amnion cells in monolayer culture with 1,25-dihydroxycholecalciferol caused, within 12 hours, a significant increase in the synthesis of prostaglandin E2, which was maintained for the duration of treatment, that is, 48 hours. These findings may be indicative of a significant physiologic role for 1,25-dihydroxycholecalciferol in metabolic processes that are important in amnion, including transport, amniotic fluid volume homeostasis, and the initiation of parturition.

Amnion↗
PubMed1987

Preterm labor: stimulation of arachidonic acid metabolism in human amnion cells by bacterial products.

There is a strong association between preterm labor and infection. Some potentially pathogenic bacteria have phospholipase activity, and it has been suggested that release of phospholipase from these organisms may increase prostaglandin E2 synthesis in amnion cells and hence initiate preterm labor. In this study we established monolayer amnion cell cultures from tissue collected at elective cesarean section at term before labor. Cells were prelabeled with tritiated arachidonic acid and then further incubated after addition of 2%, 5%, or 10% (vol/vol) filtered medium in which either group B beta-hemolytic streptococcus, Streptococcus viridans, Escherichia coli, Bacteroides fragilis, or Lactobacillus had been growing. Tritiated arachidonic acid and its metabolites released by the amnion cells in these or control incubates were extracted from culture medium and separated by high-performance liquid chromatography. Addition of conditioned medium from each of the organisms with the exception of Lactobacillus caused an increase in overall arachidonic acid metabolism. There was an increase in the ratio of cyclooxygenase to lipoxgenase metabolism and in prostaglandin E2 production in particular when compared to controls. The profile of arachidonic acid metabolism in amnion cells following addition of filtered bacterial medium resembled that obtained from amnion cells cultured following spontaneous labor. We suggest that abnormal bacterial colonization of the genital tract may lead to an increase in arachidonic acid metabolism in amnion cells with an increase in prostaglandin E2 production and the consequent initiation of preterm labor.

Amnion↗
PubMed1995

Prospective determination of chorionicity, amnionicity, and zygosity in twin gestations.

OBJECTIVE: Our purpose was to determine the predictive accuracy of a composite ultrasonographic evaluation for chorionicity, amnionicity, and zygosity in a consecutive series of twins. STUDY DESIGN: One hundred ten consecutive twins were seen for ultrasonography beginning January 1992. Chorionicity, amnionicity, and, zygosity were prospectively assessed with a composite of ultrasonographic findings (placental number, fetal sex, membrane thickness, and "twin peak" sign). Clinical and pathologic confirmation of chorionicity, amnionicity, and zygosity was available on 100 of these twins. RESULTS: The 100 twins had 3.6 +/- 1.6 ultrasonographic scans each (mean +/- SD) with the first performed at 22.6 +/- 6.9 weeks. Chorionicity, amnionicity, and zygosity were each predicted with > or = 91% sensitivity and specificity. In 35 (35%) cases zygosity could not be determined by either ultrasonographic or clinical or pathologic assessment at delivery. CONCLUSION: Chorionicity, amnionicity, and zygosity have important implications for antepartum management and prognosis of twins. By use of a composite of ultrasonographic findings, chorionicity, amnionicity, and zygosity were predicted with excellent reliability when they were prospectively tested in a heterogeneous consecutive series of twins.

Amnion↗
PubMed1989

The healing of chronic venous leg ulcers with prepared human amnion.

Forty chronic venous leg ulcers were treated, before split skin grafting, with human amnion prepared in one of the four following ways: tissue-culture-maintained, frozen, fresh or lyophilised. Although there was no significant statistical difference in the results obtained with the different preparations of amnion, we found that lyophilised amnion was at least as good as the other preparations in promoting a good take of the skin grafts and was the simplest to store and use. It also produced the shortest healing times. Frozen and fresh amnion were easier to prepare than lyophilised amnion but gave a lower graft take and a longer healing time. Tissue-culture-maintained amnion was the most difficult to prepare and gave the poorest results. Its use was abandoned during the trial because of technical difficulties and a high infection rate.

Aged↗
PubMed1977

Use of fresh amnion as a burn dressing.

Thirty-seven children with second and third degree burns dressed with amnion were compared to seventy-three children treated with Furacin (Eaton Labs, Norwich, N.Y.) dressing. Amnion was found to be as easy to use as Furacin. Fewer split thickness skin grafts were needed in amnion treated children and these patients required fewer days of hospitalization. Bacterial culture data suggests that amnion is as good as and possibly superior to nitrofurazone in decreasing the number of organisms on the burn wound. No adverse reactions to amnion were noted. The use of amnion is supported by this preliminary study and is deserving of further investigation and clinical use.

Amnion↗
PubMedDate not supplied

Passive permeability of ovine amnion and allantois to chloride--gestational changes.

The passive permeability to 36Cl of isolated pieces of amnion (112), amniochorion (41) and allantois (54) from 55 pregnant ewes was studied in vitro. There was a significant decrease in the permeability coefficient (K) with increasing age in both amnion and allantois when samples from two age groups (72 to 109; 110 to 147 days of gestation) were analysed. There was a highly significant correlation (P less than 0.001) between amnion permeability and amniotic fluid [Cl-], but none between allantoic permeability and allantoic fluid [Cl-]. Amniotic fluid osmolality decreased significantly over the last third of gestation and was significantly correlated with amniotic fluid [Cl-]. Allantoic fluid osmolality increased with age and did not correlate with allantoic fluid [Cl-]. The anion exchange blocker, SITS, significantly decreased K in the amnion in the younger age group, suggesting that anion exchange through cell membranes may be one route of Cl- movement through the young amnion. The results suggest that the permeability of the amnion may play a role in the regulation of the composition of amniotic but not allantoic fluid in sheep.

Allantois↗
PubMed1992

Glucocorticoid stimulation of amnion cell prostaglandin synthesis: suppression by protein kinase C inhibitors and independence of phorbol ester-sensitive protein kinase C.

Glucocorticoids stimulate the prostaglandin E2 production of confluent amnion cell cultures, but have no stimulatory effect on the PGE2 output of freshly isolated human amnion cells. Since protein phosphorylation may modify the responsiveness of target cells to steroids, and activators of protein kinase C (PKC), as well as corticosteroids, promote amnion cell PGE2 output by stimulating the synthesis of prostaglandin endoperoxide H synthase (PGHS), we investigated the possibility that PKC is involved in the glucocorticoid-induction of PGE2 synthesis in cultured amnion cells. The dexamethasone-induced PGE2 output of arachidonate-stimulated cells was blocked by the protein kinase inhibitors staurosporine, K-252a, H7, HA1004, and sphinganine, in a manner consistent with their effect on PKC. However, dexamethasone increased the PGE2 production of cultures treated with maximally effective concentrations of the PKC-activator compound TPA. Moreover, dexamethasone stimulated PGE2 synthesis in cultures which were desensitized to TPA-stimulation by prolonged phorbol ester treatment. Concentration-dependence studies showed that staurosporine completely (greater than 95%) blocked glucocorticoid-provoked PGE2 synthesis at concentrations which did not inhibit TPA-stimulated prostaglandin output, and that K-252a inhibited the effect of TPA by more than 95% at concentrations which decreased the effect of dexamethasone only moderately (approximately 40%). Dibutyryl cyclic AMP had no influence on the basal- or dexamethasone-stimulated PGE2 production, and on the staurosporine inhibition of the steroid effect. These results show that glucocorticoids and phorbol esters control amnion PGE2 production by separate regulatory mechanisms. It is suggested that the response of human amnion cells to glucocorticoids is modulated by protein kinase(s) other than phorbol ester-sensitive PKC and cyclic AMP-dependent protein kinase.

Alkaloids↗
PubMed1987

A product from human decidua inhibits prostaglandin production by human amnion.

Human decidua was obtained from nonlaboring women after elective cesarean section. Decidua was incubated with media alone for 20 hours and this media (decidual conditioned media) was then incubated with amnion cells in monolayer culture and amnion rings. A 90% decrease in PGE2 production by amnion cells in monolayer culture was demonstrated in the presence of decidual conditioned media when compared to controls. In short term incubations with fresh amnion, decidual conditioned media decreased the production of PGE2 in amnion by greater than 25% of the control rate of production in 17 of 21 experiments. These observations suggest that human decidua produces a factor capable of inhibiting prostaglandin production by amnion.

Amnion↗
PubMed1993

Interleukin-1 binding and prostaglandin E2 synthesis by amnion cells in culture: regulation by tumor necrosis factor-alpha, transforming growth factor-beta, and interleukin-1 receptor antagonist.

Proinflammatory cytokines may promote preterm labor in the setting of intrauterine infection. Tumor necrosis factor (TNF) and interleukin-1 (IL-1) synergistically stimulate the production of prostaglandin E2 (PGE2) by amnion cells. Transforming growth factor-beta (TGF-beta) inhibits the cytokine-stimulated PGE2 production. In the present study, we investigated the binding of IL-1 beta on human amnion cells in culture. Untreated amnion cells possessed 540 +/- 60 IL-1 receptors per cell, with a dissociation constant of 1.4 +/- 0.4 nM. Cells treated with TGF-beta 1 (10 ng/ml) had 570 +/- 110 receptors per cell. TNF-alpha (50 ng/ml) increased the number of IL-1 receptors to 2930 +/- 590. TGF-beta 1 inhibited the receptor upregulation by TNF-alpha. Cells treated with TGF-beta 1 and TNF-alpha expressed 1140 +/- 590 receptors per cell. The binding affinity was not changed by the cytokines. IL-1 receptor antagonist (IL-1ra) inhibited the stimulation of amnion cell PGE2 production by IL-1 beta, but not by TNF-alpha. Amnion cells secreted large amounts of IL-1ra (1.1 +/- 0.3 ng/10(5) cells). Treatment of the cells with TGF-beta 1 or TNF-alpha did not affect the release of IL-1ra. We conclude that IL-1 receptor expression is an important step in the regulation of the effects of cytokines on amnion cell PGE2 production.

Amnion↗