Cigarette smoke induces oxidative stress and apoptosis in normal term fetal membranes

Cigarette smoking and bacterial infections are two major risk factors associated with preterm prelabor rupture of membranes (pPROM). We hypothesized that exposure of fetal membranes to cigarette smoke extracts might induce oxidative stress (OS) and fetal membrane apoptosis, culminating in an alternate pathway to that commonly activated by infection. To test this, we characterized the production of prostanoids and biomarkers of apoptosis in normal term human fetal membrane explant cultures. Fetal membrane explants collected at term (from cesarean deliveries, not in labor) were stimulated with cigarette smoke extract (CSE) for 24 h. Two classes of prostanoids, F2-Isoprostane (F2-IsoP), a marker of OS and PGF2α, a classical uterotonin, were measured by gas chromatography/mass spectrometry. Western blot analyses of tissue lysates were performed to quantify the anti-apoptotic protein Bcl2 and actin (as a control). Fetal membrane apoptosis was detected by immunohistochemistry for active caspase 3 and confirmed by TUNEL staining for nuclear fragmentation. CSE exposure resulted in significantly more F2-IsoP production from fetal membranes (242.8 ± 79.3 pg/ml/mg of total membrane protein) compared to unstimulated controls (131.5 ± 53.1 pg/ml/mg; p < 0.0001). By contrast, PGF2α was not different in CSE vs. controls (1083 ± 527 vs. 1136 ± 835 pg/ml/mg of protein; p = 0.80). CSE-exposed tissues demonstrated a dose-dependent decrease in Bcl2 expression and increases in active caspase 3 and nuclear fragmentation in both amnion and chorion cells compared to controls. In summary, fetal membranes exposed to CSE manifest evidence of OS and apoptosis. The differential pattern of prostanoid production observed in this study supports the hypothesis that an alternate non-inflammatory pathway mediated by OS and apoptosis in pPROM may promote proteolysis resulting in membrane weakening and rupture.

Chorioamnionitis--a complex pathophysiologic syndrome

Chorioamnionitis, inflammation of the amniochorionic membrane (fetal membranes) is a very common disease but a complex syndrome associated with pregnancy. It presents a clinical impasse due to lack of knowledge of specific etiologies associated with this condition making confident clinical interventions difficult. Recent reports provide insight into genetic, epigenetic, behavioral, psychosocial, molecular and pathophysiological factors that are associated with chorioamnionitis. However, a coordinated approach in understanding causality and lack of early indicators (clinical and biomarkers) has hampered gaining knowledge about the disease status preventing proper intervention. Several reviews have provided in-depth analysis of the histologic and clinical evidence associated with chorioamnionitis. In this review, we provide a novel perspective on chorioamnionitis based on recent evidences from scientific literature on inflammation, apoptosis and genetics.

Increased Bioavailability of TNF-α in African Americans During In Vitro Infection: Predisposing Evidence for Immune Imbalance

OBJECTIVE

The objective of this study is to examine TNF-alpha and its soluble and membrane bound receptors in fetal membranes derived from blacks and whites in response to in vitro infectious stimulus, and the balance between TNF-alpha and the receptors. Fetal membranes collected from black and white women at term were maintained in an organ explant system and stimulated with lipopolysaccharide (LPS). TNF-alpha, soluble TNF receptors (sTNFR1 and sTNFR2) in culture media and membrane bound TNF receptors (TNFR1 and TNFR2) in tissue homogenates were measured. Molar ratio (TNF/sTNFR) was calculated between LPS stimulated and unstimulated (controls) cultures in both races. TNF-alpha was increased in both races after LPS stimulation and showed no difference between races (p=0.7). LPS decreased sTNFR1 in blacks, but increased in whites, showing a significant difference between races (p=0.001). In blacks sTNFR2 also decreased and increased in whites, but the results were not significant between races (p=0.4). Both TNFR1 and TNFR2 were increased in blacks after LPS stimulation whereas no such changes were seen in whites compared to controls that were also significant between races. After LPS stimulation TNF-alpha bioavailability was increased in blacks with a drop in soluble receptors and with an increase in membrane receptors. This was not evident in whites because in whites soluble receptors were increased with no change in membrane receptors. Our data demonstrated that LPS stimulation results in a molar ratio switch favoring TNF-alpha biofunction in blacks, but not in whites.

Ethnic differences in interleukin 6 (IL-6) and IL6 receptor genes in spontaneous preterm birth and effects on amniotic fluid protein levels

Preterm birth (PTB) is a significant neonatal health problem that is more common in African-Americans (AA) than in European-Americans (EA). Part of this disparity is likely to result from the differing genetic architectures of EA and AA. To begin assessing the role of these differences, patterns of genetic variation in two previously proposed candidate genes, encoding interleukin 6 (IL6) and its receptor (IL6R), were analyzed in mothers and fetuses from 496 EA birth-events (149 cases and 347 controls) and 397 birth-events in AA (76 cases and 321 controls). IL-6 levels in amniotic fluid (AF) samples were determined in a subset of these pregnancies. Case-control comparisons revealed a single SNP in IL6R associated with PTB (p=0.04 for allelic and p=0.05 for genotype association). In addition, all of the SNPs studied showed significant frequency differences between AA and EA in at least one comparison, significantly in excess of that expected from general population databases. Higher IL-6 concentrations were associated with the IL6 SNP -661 in EA preterm samples (p=0.0056), and this result seems to be driven by microbial invasion of the amniotic cavity, indicating a gene by infection interaction. These findings indicate that, as a function of IL6 genotype, EA and AA women respond differently to infection with respect to their expression of IL-6. Our data support differential genetic control of levels of IL-6 in amniotic fluid between EA and AA.

IL-1β is a Better Inducer of Apoptosis in Human Fetal Membranes than IL-6

The objective of this study was to compare two of the inflammatory cytokines (IL-1 and IL-6) elevated in both preterm labour and preterm premature rupture of the membranes (pPROM), with respect to their ability to induce fetal membrane apoptosis. Fetal membranes collected from women at term were placed in an organ explant system and stimulated with recombinant human IL-1 beta and IL-6. The expression patterns of pro-apoptotic genes (Fas, FasL, TRADD, FADD) and caspases 2, 3, 8, 9 were studied using PCR. Caspase activity and DNA fragmentation were studied using substrate assays and TUNEL respectively. Caspase 8 and 9 expressions were induced in IL-1 beta and IL-6 treated amniochorion. Caspase 2 expression was seen only in IL-1 beta stimulated tissues. When compared to control, IL-1 beta increased caspase 2, 3, 8 and 9 activities, whereas IL-6 treated membranes did not exhibit a significant change. DNA fragmentation was seen in greater numbers after IL-1 beta treatment than after IL-6 treatment. This study demonstrates that IL-1 beta is a better inducer of apoptosis in normal human fetal membranes than IL-6.

Lipopolysaccharide stimulation of 70 kilo Dalton heat shock protein messenger ribonucleic acid production in cultured human fetal membranes

OBJECTIVE

The 70 kilo Dalton heat shock protein is up-regulated when cells are under physiological stress. It prevents protein denaturation and incorrect polypeptide assembly, and inhibits apoptosis as well as the transcription of genes coding for pro-inflammatory cytokines. To evaluate if up-regulation of heat shock protein 70 can occur during pregnancy, we examined whether addition of bacterial lipopolysaccharide to human amniochorion membranes in vitro stimulated heat shock protein 70 gene transcription.

MATERIALS AND METHODS

Amniochorionic membranes (n = 5), collected at the time of elective repeat cesarean section prior to labor from normal term gestations, were placed in an organ explant system. After 48 hour in culture, the membranes were stimulated with lipopolysaccharide for 24 hours. Total RNA was extracted and subjected to an oligo dT primed reverse transcriptase reaction followed by polymerase chain reaction (PCR) using heat shock protein 70 specific primers. PCR products were hybridized with biotinylated internal probes and identified by enzyme-linked immunosorbent assay (ELISA). Results were analyzed by Mann-Whitney U test. A p < 0.05 was significant.

RESULTS

Heat shock protein 70 messenger RNA was expressed by all fetal membrane preparations both prior to and following in vitro culture. Addition of lipopolysaccharide increased the concentrations of heat shock protein 70 messenger RNA in each sample tested from a mean of 35.5 +/- 29.6 ng/milliliter (12.1-80.1 ng/milliliter) to 169.6 +/- 69.9 ng/ml (51.7-218.2 ng/milliliter) (p = 0.03).

CONCLUSION

Human fetal membranes constitutively express heat shock protein 70 messenger ribonucleic acid. Bacterial lipopolysaccharide markedly stimulated heat shock protein 70 messenger RNA gene transcription in human fetal membranes. Thus, heat shock protein 70 is inducible in fetal membranes and may facilitate fetal survival under adverse conditions.

Interleukin-10 inhibition of gelatinases in fetal membranes: therapeutic implications in preterm premature rupture of membranes

OBJECTIVE

To examine the effect of interleukin-10 on production and regulation of gelatinases by amniochorion in an in vitro model of infection.

METHODS

We placed amniochorionic membranes collected from eight women who had elective repeat cesareans at term in an organ explant culture system. After 48 hours in culture, the membranes were stimulated with lipopolysaccharide (50 ng/mL), and some were costimulated with interleukin-10 (500 ng/mL). Tissue and media samples were collected after 24-hour stimulation. Quantitative polymerase chain reactions and enzyme-linked immunosorbent assays were used to evaluate matrix metalloproteinase 2 and matrix metalloproteinase 9 messenger RNA and proteins, respectively.

RESULTS

Lipopolysaccharide stimulation induced 55.14 transcripts of matrix metalloproteinase 9, compared with 0.83 in control tissues (P <.001). Costimulation with interleukin-10 and lipopolysaccharide significantly reduced matrix metalloproteinase 9 messenger RNA levels to 10 transcripts (P <.001). Lipopolysaccharide stimulation produced 29.25 ng/mL of immunoreactive matrix metalloproteinase 9, which was reduced to 6.3 ng/mL (P(adj) =.016) after costimulation with interleukin-10. Although not significant, matrix metalloproteinase 2 messenger RNA levels were higher in lipopolysaccharide-stimulated tissues (4.37 x 10(6) transcripts) compared with control (2.8 x 10(5) transcripts; P(adj) =.08), with a significant decrease in matrix metalloproteinase 2 messenger RNA levels in interleukin-10- costimulated tissues (2.9 x 10(6); P(adj) =.007). Interleukin-10 costimulation resulted in a significant decrease in matrix metalloproteinase 2 protein production (203.1 [lipopolysaccharide] and 149.75 [with interleukin-10]; P(adj) <.001).

CONCLUSION

Interleukin-10 eliminated lipopolysaccharide induction of matrix metalloproteinase 2 and 9 in amniochorion.

Support for an infection-induced apoptotic pathway in human fetal membranes

OBJECTIVE

Lipopolysaccharide and tumor necrosis factor alpha levels are both elevated in the amniotic fluid of women during infection-associated preterm labor and premature rupture of fetal membranes. Our laboratory has shown that apoptosis is associated with premature rupture of fetal membranes but is not associated with preterm labor. The exact pathway that leads to apoptosis-mediated premature rupture of fetal membranes is still unclear. Because infection and increased inflammatory cytokine response are associated with the majority of cases of premature rupture of fetal membranes, we examined the roles of bacterial lipopolysaccharide and tumor necrosis factor alpha in inducing the proapoptotic caspase pathway in fetal membranes.

STUDY DESIGN

Amniochorionic membranes collected from women undergoing elective repeat cesarean delivery at term were placed in an organ explant system. At the end of a 48-hour incubation period, membranes were stimulated with lipopolysaccharide (50 ng/mL) and recombinant tumor necrosis factor (50 ng/mL). Total ribonucleic acid extracted from these samples was subjected to reverse transcription and two separate sets of multiple polymerase chain reaction. One set studied the expression of Fas, Fas ligand, caspase 8, Fas-associated death domain, and tumor necrosis factor receptor-associated death domain genes and the second set studied the expression of caspase 2, 4, 6, 7, and 10. Caspase 2, 3, and 9 expression was also studied by reverse transcriptase-polymerase chain reaction.

RESULTS

Multiple polymerase chain reactions and reverse transcriptase-polymerase chain reactions documented the induction of Fas and caspase 2, 3, 7, 8, and 9 genes in amniochorion after lipopolysaccharide and tumor necrosis factor stimulation compared with the nonstimulated controls. Neither lipopolysaccharide nor tumor necrosis factor induced Fas ligand expression in human fetal membranes. Caspase 3, 4, and 6, Fas-associated death domain, and tumor necrosis factor receptor-associated death domain expressions were constitutive in all the tissues tested; however, tumor necrosis factor receptor-associated death domain expression appeared stronger in tumor necrosis factor-stimulated tissues.

CONCLUSION

The presence of the signal docking proteins tumor necrosis factor receptor-associated death domain and Fas-associated death domain and the induction of caspase cascade initiators (caspase 2, 8, and 10) and effector caspases (caspase 3, 6, 7, and 9) by lipopolysaccharide and tumor necrosis factor suggest that tumor necrosis factor-tumor necrosis factor receptor-mediated apoptosis may occur in the human fetal membrane.

Distinct molecular events suggest different pathways for preterm labor and premature rupture of membranes

OBJECTIVE

On a clinical level, the etiologies associated with premature rupture of the membranes and preterm labor are virtually identical, though these conditions end in distinctly different events. This study was designed to determine differences between preterm labor and preterm premature rupture of membranes by using molecular markers of extracellular matrix degradation and apoptosis.

STUDY DESIGN

Amniochorion and amniotic fluid samples were collected from gestational age-matched groups of women undergoing cesarean delivery before term. Samples were collected from 2 groups of women, women with premature rupture of membranes and women with preterm labor with no rupture of membranes. Changes in the expression pattern of messenger ribonucleic acid for matrix metalloproteinases (MMP), tissue inhibitor of metalloproteinases (TIMP), and pro-apoptotic (p53 and Bax) and anti-apoptotic (Bcl-2) proteins were identified by quantitative polymerase chain reaction. Enzyme-linked immunosorbent assay was used to determine the levels of these proteins in the amniotic fluid. Multiplex polymerase chain reaction was performed to study the expression of Fas-Fas ligand-associated pro-apoptotic genes. Unpaired nonparametric, 2-tailed Mann-Whitney U test was used to determine statistical significance of quantitative polymerase chain reaction and enzyme-linked immunosorbent assay (P <.05 was considered significant).

RESULTS

Quantitative polymerase chain reaction results demonstrated an increased mRNA expression for MMP2, MMP9, and MT1-MMP and a decreased expression for TIMP2 in prematurely ruptured membranes compared with preterm labor membranes. Enzyme-linked immunosorbent assay documented increases in the amniotic fluid concentrations of immunoreactive and bioactive MMP2 and MMP9 and immunoreactive MMP3 and a decreased TIMP2 concentration in fluids obtained from the premature rupture of membranes group compared with the preterm labor group. The pro-apoptotic genes p53 and bax were up-regulated in premature rupture of membranes when compared with preterm labor. Anti-apoptotic gene (Bcl-2 ) expression was increased in preterm labor membranes compared with prematurely ruptured membranes. Interleukin-18 (a pro-apoptotic cytokine) was increased in the amniotic fluid during premature rupture of membranes compared with preterm labor. Prematurely ruptured membranes also demonstrated fragmented deoxyribonucleic acid and expression of Fas and caspase 8 (apoptosis initiator), which were all absent in preterm labor membranes.

CONCLUSIONS

We have begun to delineate 2 divergent molecular pathways for premature rupture of membranes and preterm labor. Most likely, this is the beginning of the identification of differences that will become evident with the use of molecular biology.

Programmed cell death (apoptosis) as a possible pathway to metalloproteinase activation and fetal membrane degradation in premature rupture of membranes

OBJECTIVE

Increased matrix metalloproteinase 2 expression and activity are associated with premature rupture of fetal membranes. A proapoptotic protein produced in response to deoxyribonucleic acid fragmentation, p53, can bind to the matrix metalloproteinase 2 gene promoter and cause increased gene expression. It promotes apoptosis by inducing the expression of the proapoptotic bax gene and inhibiting the antiapoptotic bcl-2 gene. This study was undertaken to investigate the expression pattern of apoptotic elements in pregnancy complications that may cause increased expression of the gene for matrix metalloproteinase 2.

STUDY DESIGN

Amniochorial membranes were collected from the following groups of women: (1) women with premature rupture of fetal membranes, (2) women with preterm labor and intact membranes, and (3) women with term labor after vaginal delivery. Deoxyribonucleic acid fragmentation was tested with ligation-mediated polymerase chain reaction and the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyribonucleoside triphosphate end-labeling assay. Matrix metalloproteinase 2, p53, bcl-2, and bax gene expression patterns were studied with quantitative competitive polymerase chain reaction. Statistical analysis was performed with the Tukey-Kramer multiple comparison test.

RESULTS

Quantitative competitive polymerase chain reaction documented a 10-fold increase in the expression of the gene for matrix metalloproteinase 2 in premature rupture of fetal membranes with respect to term and preterm labor. This induction coincided with an increase in the expressions of the proapoptotic genes p53 and bax and a drop in the expression of the antiapoptotic gene bcl-2. Ligation-mediated polymerase chain reaction revealed deoxyribonucleic acid fragmentation in specimens from premature rupture of fetal membranes and not in those from preterm labor or labor at term. Histochemical analysis documented fragmented deoxyribonucleic acid in chorionic and amniotic cells.

CONCLUSION

This study suggests that apoptosis is associated with premature rupture of fetal membranes. Deoxyribonucleic acid fragmentation, associated with elevations in the levels of the two proapoptotic gene products evaluated (p53 and bax ) and a drop in the level of the antiapoptotic bcl-2, was seen in premature rupture of the fetal membranes. Induction of matrix metalloproteinase 2 may be a function of p53 gene expression increase in premature rupture of fetal membranes.

Amniochorion gelatinase-gelatinase inhibitor imbalance in vitro: a possible infectious pathway to rupture

OBJECTIVE

To estimate the effect of lipopolysaccharide on gelatinases and tissue inhibitors of matrix metalloproteinase 2 (gelatinase inhibitor) balance in human fetal membranes.

METHODS

Amniochorionic membranes in organ explant were stimulated with 1000 ng/mL lipopolysaccharide for 24 hours after a 48-hour preincubation period. Quantitative competitive polymerase chain reaction (PCR) was done to quantitate messenger RNAs for gelatinase A and B (matrix metalloproteinase 2 and 9) and tissue inhibitor of metalloproteinase 2. Protein levels were assayed by enzyme-linked immunosorbant assay. The molar ratio between gelatinases and tissue inhibitor of metalloproteinase 2 was calculated. Statistical evaluation was done by Mann-Whitney U test.

RESULTS

Lipopolysaccharide stimulation produced 3.6 x 10(6) and 366 transcripts of gelatinase A and B, respectively, compared with only 5.9 x 10(4) (P = .009) and three transcripts (P = .006), respectively, in the controls. Lipopolysaccharide stimulation released 210 ng/mL compared with 7 ng/mL of gelatinase A and B proteins compared with 120 (P = .01) and 4.6 ng/mL (P = .3) in controls, respectively. Control amniochorion produced 5.7 x 10(5) transcripts of tissue inhibitor of metalloproteinase 2, whereas lipopolysaccharide stimulation produced 4.1 x 10(5) transcripts (P = .69). Lipopolysaccharide reduced the release of this inhibitor from 114 ng/mL to 68 ng/mL (P = .007). The molar ratio between gelatinases and tissue inhibitor of metalloproteinase 2 increased from a balanced ratio of 1:1 to 3.1:1 after 1000 ng/mL of lipopolysaccharide.

CONCLUSION

Lipopolysaccharide increased the expression and release of gelatinases and decreased its inhibitor, which shifted the balance in favor of gelatinase activity leading to membrane degradation that predisposes to premature rupture of membranes.

MMP/TIMP imbalance in amniotic fluid during PROM: an indirect support for endogenous pathway to membrane rupture

OBJECTIVE

We theorize that excessive degradation of the fetal membrane extracellular matrix (ECM) by specific matrix metalloproteinases (MMPs) results in preterm premature rupture of the membranes (PROM). Active, inhibitor free MMP2 and 9 (gelatinase A and B respectively) can degrade the amniochorion basement membrane Type IV collagen to initiate rupture. This study examines the levels of the gelatinases and their natural inhibitors (tissue inhibitor of matrix metalloproteinases-TIMPs) in the amniotic fluid during PROM, preterm labor (PTL) and at term.

METHODS

A total of 51 AF samples were collected from the following groups of patients. Group 1: Women with PTL and no ROM (n = 16) Group 2: Women with PROM (n = 16) irrespective of labor status Group 3: Women at term with intact membranes undergoing cesarean delivery irrespective of labor status (n = 19). ELISA was used to assay MMP2, MMP9, TIMP1 and TIMP2 levels in the amniotic fluid. The active, TIMP free levels of MMP2 were quantitated by zymography followed by computerized densitometry. Active MMP9 was measured using a bioassay that specifically detects MMP9 activity. Statistical analysis was performed by Tukey-Kramer multiple comparison method.

RESULTS

PROM is associated with increased MMP2 levels (mean 2125 ng/ml;) when compared with term (mean 1455 ng/ml; p < 0.01) or PTL where a non significant increase was seen (mean 1862 ng/ml; p = ns). MMP9 levels were higher in PROM (mean 15.03 ng/ml) than at term (mean 1.14 ng/ml; p < 0.001) or PTL (mean 3.75 ng/ml; p < 0.01). TIMP1 levels were slightly increased during PROM (mean 3143 ng/ml) compared to term (mean 1892 ng/ml; p < 0.05) pr PTL where a non significant change was seen (mean 2406 ng/ml; p = ns). TIMP2 levels were decreased in PROM (mean 98 ng/ml) compared with term (mean 176 ng/ml; p < 0.05) and PTL (mean 236 ng/ml; p < 0.001). Active, TIMP free MMP2 levels were increased during PROM (mean 233 pg/ml) compared to those at term (mean 132 pg/ml; p < 0.05) or PTL (mean 132 pg/ml; p < 0.05). Active forms of MMP9 were seen only during PROM (mean 632 pg/ml).

CONCLUSION

Active, TIMP free forms of MMP2 and 9 are increased in the amniotic fluid of women with PROM. These MMPs can degrade the amniochorion basement membranes and other ECM components resulting in PROM.

Stromelysins in placental membranes and amniotic fluid with premature rupture of membranes

OBJECTIVE

To determine the expression and site of production of stromelysins in fetal membranes and to measure stromelysin 1 levels in amniotic fluid and amniochorion culture media.

METHODS

Amniochorionic membranes were cultured from organ explant. Membranes were stimulated with lipopolysaccharide for 24 hours after a 48-hour preincubation period. Membranes were also collected from women after vaginal deliveries. RNA samples from those tissues were subjected to reverse transcriptase-polymerase chain reaction using primers specific for stromelysin 1, stromelysin 2, stromelysin 3, and matrilysin. In situ hybridization and immunohistochemistry were used to localize stromelysin mRNA and peptide. Levels of stromelysin 1 in culture media and amniotic fluid collected from women with preterm premature rupture of membranes (PROM) and at term with intact membranes were compared using enzyme-linked immunosorbant assay.

RESULTS

Amniochorion in culture and from laboring and nonlaboring women expressed all three stromelysins. In situ hybridization showed stromelysin mRNA in amnion, chorion, and extracellular matrix. Immunohistochemical analysis localized stromelysin 1 protein to those same regions. Amniotic fluid levels of stromelysin 1 were higher in preterm PROM amniotic fluids (median 3.2 ng/mL) compared with term deliveries with intact membranes (median 1.3 ng/mL) (P = .02). Lipopolysaccharide stimulation in culture increased the release of stromelysin 1 from fetal membranes compared with control (median 70.35 versus 15.8 ng/mL, respectively, P = .05).

CONCLUSION

Human fetal membranes are a source of stromelysins 1, 2, and 3. Increased stromelysin 1 during preterm PROM and in vitro after lipopolysaccharide stimulation suggests a possible effect of that matrix metalloproteinase in PROM.

Immunoreactivity of human fetal membranes to peptidoglycan polysaccharide (PGPS): cytokine response

OBJECTIVE

Group-B Streptococcus has been associated with preterm labor and other pregnancy related complications. This study was performed to evaluate the effect of peptidoglycan polysaccharide (PGPS) derived from a beta hemolytic Streptococcal cell wall on amniochorion cytokine production and to compare PGPS effects with lipopolysaccharide (LPS), which is the Gram negative counterpart of PGPS.

STUDY DESIGN

Amniochorionic membranes collected from women not in labor, and undergoing elective repeat C-section were placed in an organ explant system. Membranes were stimulated separately with 50 ng/ml of small (100p), large (10s) fractions of PGPS or LPS respectively immediately after collection and after a stabilization period of 48 hrs. Media samples were collected at 3, 6, 9, 12 and 24 hrs for protein analysis after each stimulation. Media samples were analyzed by ELISA for IL-6 and IL-8.

RESULTS

Both forms of PGPS and LPS stimulated IL-6 and IL-8 production by human fetal membranes. Of note is that LPS stimulated IL-6 to a greater degree than IL-8, while PGPS stimulated IL-8 to a greater degree than IL-6. No statistical difference was seen in the levels of either one of these cytokines for the larger or smaller fragments of PGPS. Time course studies documented a 3-hour lag phase when tissues are stimulated directly after collection which was absent when tissues are stimulated after a 48-hour stabilization period.

CONCLUSION

Both PGPS and LPS stimulate cytokine production differently from fetal membranes. This supports the theory that different bacteria may affect the host in contrasting ways which may lead to a distinct host response, i.e. PROM vs. PTL.

Presence of four tissue inhibitors of matrix metalloproteinases (TIMP-1, -2, -3 and -4) in human fetal membranes

PROBLEM

Matrix metalloproteinases play a critical role in fetal membrane extracellular matrix (ECM) homeostasis. Remodeling of the ECM during normal placental development is a balanced activity between various matrix metalloproteinases and their tissue-specific counter-regulatory proteins (tissue inhibitors of matrix metalloproteinases [TIMPs]). We have reported the presence of TIMP-1 and TIMP-2 in placental membranes in culture. In this study we have investigated the membrane expression of TIMP-1 and TIMP-2 during labor and nonlabor conditions and also the presence of two novel TIMP family members (TIMP-3 and TIMP-4).

METHOD OF STUDY

Amniochorionic membranes collected from women undergoing Cesarean section and were cultured in an organ explant system. Membranes were also collected from laboring women after vaginal delivery. Samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) using primers specific for TIMP-1, TIMP-2, TIMP-3, and TIMP-4. Localization of TIMP mRNAs was accomplished by in situ hybridization, and peptides were localized by immunocytochemistry.

RESULTS

RT-PCR data demonstrated the expression of all the TIMPs in tissues from laboring and nonlaboring women as well as in cultured membranes. TIMP-4 expression was seen in RT-PCR, however, only a faint band was visible in all the tissues tested. In situ hybridization localized the TIMP mRNAs to the amnion, chorion, and to scattered cells in the connective tissue.

CONCLUSION

Human fetal membrane cells (amniochorion and decidua) express mRNA for all the TIMPs studied so far.

The effect of transforming growth factor and interleukin-10 on interleukin-8 release by human amniochorion may regulate histologic chorioamnionitis

OBJECTIVE

Amniochorion is a source of interleukin-8 during infection and inflammation. In this study we investigate the role of 2 immunoinhibitory cytokines, transforming growth factor and interleukin-10, in regulating interleukin-8 production from human fetal membranes and define their mechanism of regulation.

STUDY DESIGN

Amniochorion was placed in an organ explant system for 72 hours. Tissues were stimulated with lipopolysaccharide (50 ng/mL), lipopolysaccharide plus transforming growth factor-beta (50/50, 50/100), transforming growth factor-beta (50 and 100 ng/mL), lipopolysaccharide plus interleukin-10 (50/50 and 50/100), and interleukin-10 (50 and 100 ng/mL) in culture. Tissue and media samples were frozen until quantitation of interleukin-8 messenger ribonucleic acid and protein. Quantitation of messenger ribonucleic acid was performed by quantitative competitive polymerase chain reaction and protein by enzyme-linked immunoassay, respectively.

RESULTS

Lipopolysaccharide-stimulated tissues produced approximately 6 x 10(6) molecules per microliter of interleukin-8 messenger ribonucleic acid compared with 6 x 10(3) molecules per microliter in controls. Transforming growth factor-beta alone and lipopolysaccharide plus transforming growth factor-beta stimulation produced 6 x 10(5) and 6 x 10(4) molecules of interleukin-8 messenger ribonucleic acid per microliter, respectively. Tissues stimulated with lipopolysaccharide plus 50 ng/mL interleukin-10 produced approximately 600 molecules per microliter of interleukin-8 messenger ribonucleic acid, whereas no amplifiable messenger ribonucleic acid was detected in tissues treated with lipopolysaccharide plus 100 ng/mL interleukin-10. Tissues treated with interleukin-10 alone produced 6 x 10(3) molecules of messenger ribonucleic acid, similar to control levels. Enzyme-linked immunosorbent assay data showed similar levels of interleukin-8 peptide release from lipopolysaccharide and lipopolysaccharide plus transforming growth factor-beta-treated fetal membranes. A dose-dependent decrease in interleukin-8 peptide release was seen in tissues treated with lipopolysaccharide plus interleukin-10, whereas stimulation with transforming growth factor or interleukin-10 alone resulted in interleukin-8 peptide release similar to that of control levels.

CONCLUSION

Transforming growth factor-beta seems to have no effect on interleukin-8 protein production in the presence of an infectious agent; however, a drop in messenger ribonucleic acid levels was observed. Interleukin-10 in the presence of lipopolysaccharide showed down-regulation of interleukin-8 messenger ribonucleic acid expression and peptide production. These data suggest that fetal membrane interleukin-8 production can be controlled by interleukin-10 during an infectious process.

Expression of a progelatinase activator (MT1-MMP) in human fetal membranes

PROBLEM

The finding of MMP-2 (which degrades type IV collagen) and TIMP-2 (the tissue inhibitor of MMP) in fetal membranes suggests the possibility of membrane self-destruction as an etiology of premature rupture of fetal membranes. MMP-2 is activated by a membrane-bound MMP (MT1-MMP). This study was undertaken to detect the presence of MT1-MMP in human fetal membranes.

METHOD OF STUDY

Fetal membranes were placed in an organ explant system and stimulated with lipopolysaccaride (LPS). MT1-MMP expression was studied in frozen tissues by reverse transcriptase (RT)-polymerase chain reaction (PCR) using primers designed in our laboratory. DNA sequence analysis was performed to verify the specificity of PCR products. In situ hybridization and immunocytochemistry were used to localize MT1-MMP mRNA and peptide, respectively.

RESULTS

RT-PCR data indicated the presence of mRNA for MT1-MMP in fetal membranes. Although PCR is not quantitative, no differences in mRNA band intensities were noticed after LPS stimulation. MT1-MMP expression was constitutive throughout the culture period. In situ hybridization demonstrated amnion, chorionic laeve, cytotrophoblast cells, and the cells in the reticular and spongy layer of the extracellular matrix as the origin of MT1-MMP mRNA and peptide.

CONCLUSIONS

This is the first study documenting the amniochorionic membrane as a source of MT1-MMP mRNA and peptide. Activation of progelatinase A requires the presence of this membrane-associated MMP. The finding of MT1-MMP in a tissue already known to produce MMP-2 and TIMP-2 documents the full system for activation and inhibition of this gelatinase. During infection, an imbalance in the expression of MT1-MMP, MMP-2 and TIMP-2 may constitute an endogenous pathway of membrane degradation.

IL-15, a novel cytokine produced by human fetal membranes, is elevated in preterm labor

PROBLEM

Interleukin (IL)-15 is a novel cytokine known to have functions similar to those of IL-2 in the cell-mediated immune response. The objectives of this study were to determine whether IL-15 levels change in labor or preterm labor and to identify the regulatory agents and the site of production of IL-15.

METHOD OF STUDY

Amniochorionic membranes were cultured in an organ explant system and were stimulated with lipopolysaccharides (LPSs). Samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) using specific primers for IL-15 and IL-2. The localization of mRNA and protein was accomplished by in situ hybridization and immunocytochemistry. IL-15 was measured in culture media and amniotic fluid from term and preterm gestations by enzyme-linked immunoadsorbent assay (ELISA).

RESULTS

RT-PCR indicated the expression of IL-15 mRNA in the amniochorion. In situ hybridization and immunocytochemistry documented that mRNA and peptide for IL-15 are found in amnion, chorion, and decidual cells. ELISA results indicated no significant increase of IL-15 peptides in the culture media after LPS stimulation. Maximum levels of this cytokine were seen in the amniotic fluid (AF) of women with preterm labor compared to term labor. AF levels were not higher in preterm-labor patients with proved infection compared with those without infection. RT-PCR-based detection also showed the presence of two isoforms of IL-15 mRNA known to code for two different leader peptide sequences. IL-2 mRNA expression was not observed in the fetal membranes.

CONCLUSIONS

The presence of IL-15 mRNA and peptide in the amniochorion and decidua and its increased presence in the AF during preterm labor suggests a possible role for IL-15 in preterm labor. Amniochorion is also shown to possess two IL-15 isoform leader sequences, the differential expression of which may be involved in the regulation of IL-15 secretion.

Collagenolytic enzymes (gelatinases) and their inhibitors in human amniochorionic membrane

OBJECTIVE

This study was designed to investigate the presence of matrix metalloproteinase-2 (gelatinase A), matrix metalloproteinase-9 (gelatinase B), and their natural inhibitors in both cultured amniochorionic membrane and membrane obtained from women with infection-associated preterm labor.

STUDY DESIGN

Amniochorionic membranes were collected from women with documented intraamniotic infection and from women not in labor undergoing elective repeat cesarean section with no signs of infection or other complications of pregnancy. Normal membranes were cultured and exposed to endotoxin and peptidoglycan polysaccharide. Messenger ribonucleic acid expression for gelatinase A, gelatinase B, and tissue inhibitors of matrix metalloproteinase types 1 and 2 was studied with use of reverse transcriptase-polymerase chain reaction and localization of messenger ribonucleic acid was accomplished with use of in situ hybridization. Release of gelatinases from the membranes was studied with gelatin zymography. Tissue inhibitors of matrix metalloproteinase peptides were localized with use of immunocytochemistry.

RESULTS

The expression of matrix metalloproteinase types 2 and 9 was seen in amniochorionic membranes in culture. Matrix metalloproteinase-2 was seen in membranes from nonlaboring women and in women with intraamniotic infection, whereas matrix metalloproteinase-9 was seen only in membranes from women with intraamniotic infection. The matrix metalloproteinase-9 expression could also be induced by lipopolysaccharide or peptidoglycan polysaccharide stimulation in culture. In situ hybridization localized messenger ribonucleic acid for these matrix metalloproteinases to both amnion and chorion. Zymogram studies showed the activity of matrix metalloproteinase-2 in normal resting membrane and cultured membrane. Matrix metalloproteinase-9 was induced by culture conditions. Tissue inhibitor of matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-2 messenger ribonucleic acid was seen in normal, infected, and cultured membranes. In situ hybridization data indicated that these messages were mainly produced by chorion, but they were also seen in amnion. Immunohistochemistry demonstrated the presence of tissue inhibitor of matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-2 peptides in both amnion and chorion and in cells of the reticular layer of the matrix.

CONCLUSION

Normal amniochorionic membrane is a source of matrix metalloproteinase-2 and tissue inhibitors of matrix metalloproteinases. Culture conditions and infection induce matrix metalloproteinase-9 expression and release from amniochorion. These findings suggest that these collagenolytic enzymes may play a role in premature rupture of the membranes in infection, which can lead to preterm labor.

Interleukin-10 and transforming growth factor-beta inhibit amniochorion tumor necrosis factor-alpha production by contrasting mechanisms of action: therapeutic implications in prematurity

OBJECTIVE

This study was designed to detect the regulatory effect of the immunoinhibitory cytokines interleukin-10 and transforming growth factor-beta on the amniochorion production of tumor necrosis factor-alpha.

STUDY DESIGN

Amniochorionic membranes were collected from women undergoing elective repeat cesarean section with no history of infection. Membranes were placed in organ explant culture for 48 hours and then stimulated with lipopolysaccharide (50 ng/ml), lipopolysaccharide plus interleukin-10 (50/ 50, 50/100 ng/ml), interleukin-10 (50 and 100 ng/ml), lipopolysaccharide plus transforming growth factor-beta (50/50 and 50/100 ng/ml), and transforming growth factor-beta (50 and 100 ng/ml). At the end of a 24-hour stimulation tissue samples were frozen for ribonucleic acid analysis and media samples were frozen for enzyme-linked immunosorbent assay. Quantitation of the messenger ribonucleic acid was accomplished by quantitative competitive polymerase chain reaction, and tumor necrosis factor-alpha protein was assayed by use of enzyme-linked immunosorbent assay.

RESULTS

Lipopolysaccharide stimulation of fetal membranes produced approximately 60,000 molecules of tumor necrosis factor-alpha messenger ribonucleic acid, whereas control tissue produced none. Lipopolysaccharide plus interleukin-10 stimulation resulted in a dose-dependent decrease in tumor necrosis factor-alpha messenger ribonucleic production (transcriptional regulation) to 6000 (50/50) and 600 (50/100) molecules. Enzyme-linked immunosorbent assay performed on media samples from these experiments demonstrated a dose-dependent reduction in tumor necrosis factor-alpha peptide release. Stimulation of membranes with lipopolysaccharide plus transforming growth factor-beta had minimal effects on tumor necrosis factor-alpha messenger ribonucleic acid and protein production compared with lipopolysaccharide-treated samples. Membranes stimulated with interleukin-10 alone showed no effect on messenger ribonucleic acid or protein levels and remained similar to the levels seen in control tissues. In the absence of lipopolysaccharide, transforming growth factor-beta treatment produced a dramatic decrease in tumor necrosis factor-alpha peptide levels without affecting messenger ribonucleic acid levels.

CONCLUSION

In the presence of a stimulatory agent, interleukin-10 down-regulates tumor necrosis factor-alpha release from cultured human amniochorionic membranes. Transforming growth factor-beta seems to have some stimulatory effect on transcription, and no effect on translation was seen with concurrent lipopolysaccharide stimulation. However, down-regulation of tumor necrosis factor-alpha peptide by transforming growth factor was seen in fetal membranes when not overridden by an inflammatory stimulant. This study suggests that interleukin-10 and transforming growth factor-beta can regulate tumor necrosis factor-alpha release from amniochorion under different conditions and by a different mechanism.

Interleukin-10 inhibition of interleukin-6 in human amniochorionic membrane: transcriptional regulation

OBJECTIVE

Our purpose was to study the regulatory effects of recombinant interleukin-10 on interleukin-6 messenger ribonucleic acid and protein production by human fetal membranes.

STUDY DESIGN

Amniochorionic membranes were collected from women undergoing elective cesarean section. Membranes were maintained in an organ explant system and stimulated with media containing lipopolysaccharide (50 ng/ml) and various amounts of recombinant interleukin-10 (10, 50, 100 ng/ml). Experiments were conducted in a dose- and time-dependent manner. Transcription and translation of interleukin-6 were monitored with quantitative reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Interleukin-10 stimulation of amniochorionic membranes in culture produced a dose-dependent decrease in the production of interleukin-6 messenger ribonucleic acid and protein. Quantitative polymerase chain reaction was used to document a decrease in interleukin-6 messenger ribonucleic acid, which paralleled the decrease in peptide levels as detected with enzyme-linked immunosorbent assay. The interleukin-10 effect was present only when tissue was concurrently stimulated with lipopolysaccharide. Interleukin-10 inhibition could not be produced in the absence of lipopolysaccharide stimulation.

CONCLUSION

Addition of interleukin-10 to culture media leads to transcriptional regulation of interleukin-6, which results in decreased production of both messenger ribonucleic acid and protein by human amniochorionic membranes. The decrease in interleukin-6 is a dose-dependent effect of interleukin-10. This finding may have important implications with respect to a possible role for interleukin-10 or an interleukin-10 stimulatory factor in the management of preterm labor associated with the presence of inflammatory cytokines.

Inflammatory cytokine (interleukins 1, 6 and 8 and tumor necrosis factor-alpha) release from cultured human fetal membranes in response to endotoxic lipopolysaccharide mirrors amniotic fluid concentrations

OBJECTIVE

This study was conducted to quantitate and compare the amount of cytokines released from human fetal membranes in response to treatment with bacterial lipopolysaccharide and to compare this with amniotic fluid levels.

STUDY DESIGN

Amniochorionic membranes were collected from women undergoing elective repeat cesarean section and showing no signs of infection- or pregnancy-related complications. Membranes were maintained in an organ explant system and stimulated with bacterial lipopolysaccharide for 24 hours. Media samples were collected and stored at -20 degrees C until cytokine levels were assayed by enzyme-linked immunosorbent assay.

RESULTS

Enzyme-linked immunosorbent assay results demonstrated that lipopolysaccharide stimulated production of interleukins 1, 6 and 8 and tumor necrosis factor-alpha by the fetal membranes in comparison with the control cultures. A greater release of interleukin-6 and interleukin-8 compared with interleukin-1 and tumor necrosis factor-alpha was noticed. The relationships between cytokine concentrations observed in culture mirror those seen in amniotic fluid.

CONCLUSION

Amniochorionic membranes can respond to an infectious process with increased secretion of interleukins 1, 6 and 8 and tumor necrosis factor-alpha. Cytokines produced from both amnion and chorion (interleukin-6 and interleukin-8) are released in greater quantities than those cytokines produced from chorion or amnion alone (interleukin-1 and tumor necrosis factor-alpha). These studies support a major role for amnion in infection-induced preterm labor.

The use of power Doppler and color power angiography in fetal imaging

OBJECTIVE

The potential usefulness of a new color Doppler ultrasonography technique called color power angiography in imaging fetal anatomy is presented.

STUDY DESIGN

An ultrasonography system set on color power angiography was used to image fetal anatomy. Perfusion of normal organs was compared, with several fetuses demonstrating pathologic disorders of these organ systems. Color power angiography was compared with standard color Doppler imaging.

RESULTS

We were able to demonstrate detailed imaging of the fetal vasculature in the lung, kidney, and brain. Abnormal lung and renal anatomy could be visualized by the distinctive perfusion "footprint." Fetal movement compromised the ability of color power angiography to visualize these structures but could be overcome by judicious use of the cineloop and persistence functions. Color power angiography was found to be more sensitive to low-flow states than was Doppler imaging.

CONCLUSION

Color power angiography, which is more sensitive to low-flow states than color Doppler imaging is, may be useful in the imaging of normal and abnormal fetal anatomic structures.

Amniochorion: a source of interleukin-8

PROBLEM

Preterm labor and premature rupture of the membranes are major complications of pregnancy. We have reported the possible role of amniochorionic membrane in the production of inflammatory cytokines and the early onset of labor. This study was conducted to detect the expression of IL-8 mRNA and peptide production in cultured fetal membranes.

METHOD

Amniochorionic membranes were collected from women undergoing elective cesarean section at term. Membranes were cultured in an organ explant system and the expression of IL-8 was studied over a 10-day period by RT-PCR and in situ hybridization. IL-8 peptide localization was accomplished using immunocytochemistry.

RESULTS

Constitutive expression of IL-8 mRNA in cultured fetal membranes was demonstrated in both amniotic and chorionic leave cells. mRNA and peptide for IL-8 was homogeneously distributed throughout the amniotic and chorionic cells.

CONCLUSION

Human amniochorionic membrane is a source of IL-8 mRNA and peptide.

Expression of inflammatory cytokines (interleukin-1 beta and interleukin-6) in amniochorionic membranes

OBJECTIVE

This study was designed to investigate the expression of inflammatory cytokines (interleukin-1 beta and interleukin-6) by fetal membranes in response to infection in vivo and to endotoxin in organ culture.

STUDY DESIGN

Amniochorionic membranes were collected from infected and uninfected women and analyzed for cytokine messenger ribonucleic acid and protein. Normal membranes were cultured and exposed to endotoxin. Messenger ribonucleic acid expression was analyzed by reverse transcriptase-polymerase chain reaction. Cellular localization of messenger ribonucleic acid and protein was determined by in situ hybridization and immunocytochemical evaluation, respectively.

RESULTS

Messenger ribonucleic acid for interleukin-1 beta appeared to be increased in infected or endotoxin-stimulated amniochorionic membranes, whereas interleukin-6 messenger ribonucleic acid was only observed in infected membranes or after endotoxin stimulation. Interleukin-1 beta messenger ribonucleic acid was localized exclusively to chorionic cells, whereas protein was observed in both chorion and amnion. Interleukin-6 messenger ribonucleic acid and protein were produced in both amniotic and chorionic cells.

CONCLUSION

Amniochorionic membranes are a site of inflammatory cytokine production. These findings may have significance in preterm labor or premature rupture of membranes.

Organ culture of amniochorionic membrane in vitro

PROBLEM

The purpose of the study was to develop a novel method of amniochorionic membrane culture aimed at maintaining tissue integrity.

METHOD

Amniochorionic membranes were collected from women prior to labor, undergoing elective cesarean section, with no history of infection or pregnancy related complication. Fetal membranes were maintained in culture for up to ten days. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a "house keeping" gene and inflammatory cytokine mRNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) at various periods of culture. mRNA localization was performed by in situ hybridization.

RESULTS

GAPDH gene expression was seen throughout the culture period. Inflammatory cytokine mRNA (IL-1 alpha, IL-1 beta and IL-6) were also detected during culture. Cellular and tissue morphology appeared normal.

CONCLUSIONS

The culture technique we propose is a simple organ explant system which maintains the morphology and autocrine/paracrine relationships within this tissue.

Expression of TNF-alpha and TNFR p55 in cultured amniochorion

PROBLEM

Preterm labor and PROM are major complications of pregnancy. We have reported the possible role of amniochorionic membrane as it relates to the production of cytokines and the early onset of labor. Amniochorion is capable of responding to an infectious process with the production of IL-6 and IL-1 beta. Here we examine the expression of TNF-alpha and TNFR in amniochorion.

METHOD

Amniochorionic membranes were collected and maintained in an organ explant system. Samples were frozen and/or fixed for RT-PCR, in situ hybridization, and immunocytochemistry.

RESULTS

RT-PCR demonstrated mRNA for TNF-alpha and in situ hybridization localized mRNA in chorion and amnion. Immunocytochemistry demonstrated TNF-alpha peptide in amnion but not in chorion. Immunocytochemical localization of TNFR indicates presence of that peptide in both amnion and chorion.

CONCLUSIONS

We conclude that the fetal membranes are sources of TNF-alpha and TNFR, supporting our previous work indicating that fetal membranes are active participants in the response to intraamniotic infection.

Active expectant management in very early gestations complicated by premature rupture of the fetal membranes

Premature rupture of the membranes (PROM) in the previable gestation is frequently associated with fetal or neonatal death. Passive expectant management is successful in only a small minority of cases. Women presenting with PROM at < or = 27 weeks' gestation were treated with tocolysis and prophylactic antibiotics and delivered electively for lung maturity. The corrected perinatal survival was > 92%. The mean latency phase was 21.6 days (+/- 18.12 SD). Twenty-one percent of patients presented in labor; the mean latency phase for this subgroup was 14.4 (+/- 8.54) days. Nineteen patients (79%) had a latency phase > 7 days, and 14 (58%) had a latency phase > 14 days. Thirty-nine percent of infants required < 48 hours of mechanical ventilation. Six infants were delivered with intraventricular hemorrhage; in all cases it was grade 1 or 2. There were three (12.5%) postpartum infections and three septic neonates. Active expectant management using tocolysis and prophylactic antibiotics was associated with a prolonged latency phase, low infectious morbidity and good neonatal outcome.

Differential protein binding of ceftizoxime in cord versus maternal serum

Ceftizoxime concentrations are higher in cord blood and amniotic fluid than in maternal blood. More avid binding to fetal serum proteins is a suggested mechanism. We measured ceftizoxime protein binding in fetal and maternal blood and documented significantly less protein binding to fetal proteins (21.9% vs 57.8%).

Transfer of Timentin (ticarcillin and clavulanic acid) across the in vitro perfused human placenta: comparison with other agents

OBJECTIVES

In vitro perfusion of human placentas was used to quantify the net placental transfer of ticarcillin and clavulanic acid.

STUDY DESIGN

Placentas were obtained from uncomplicated pregnancies at term. The maternal and fetal circulations were reestablished at flow rates of 17.5 ml/min and 5 ml/min, respectively. Open circulations were used to evaluate steady-state pharmacodynamics and transplacental gradient formation. Drug levels were measured by high-pressure liquid chromatography.

RESULTS

The clearance index of ticarcillin was 0.037 +/- 0.004. The fetal/maternal ratio was 0.91. Therapeutic concentrations of clavulanate (2 to 6 micrograms/ml) in the maternal media resulted in undetectable transfer to the fetal compartment. By using higher levels of clavulanate, a clearance index of 0.061 +/- 0.001 (mean +/- SEM) and 1:1 fetal/maternal gradient was obtained.

CONCLUSIONS

These data correspond to relatively low transfer of ticarcillin with a cord/maternal ratio of < 1. Clavulanate transfer is slightly greater. Agents with similar activity and superior transfer would optimize intrauterine treatment.

Trimethoprim and sulfamethoxazole transfer in the in vitro perfused human cotyledon

Utilizing the in vitro human placental model, we studied the placental transfer of trimethoprim and sulfamethoxazole. At trimethoprim concentrations of 7.2 micrograms/ml, only 1.4 micrograms/ml was transported across the placenta after 1 h, and at concentrations of 1.0 microgram/ml, one half the usual serum level, only 0.08 microgram/ml was transported across the placenta. Maternal concentrations of sulfamethoxazole of 29.6 and 127.7 micrograms/ml resulted in concentrations of 5.1 and 14.8 micrograms/ml on the fetal side, respectively. Thus, it would appear that trimethoprim is slowly transported across the placenta and in low concentrations whereas sulfamethoxazole readily crosses the placenta. The combination of these drugs is useful for treatment of bacteriuria. It may also prove to be especially useful for Pneumocystis carinii infections in pregnant women with AIDS. With a half-life of 13 h for trimethoprim and 6 h for sulfamethoxazole, the drugs are not likely to achieve toxic levels in the fetal compartment. Thus, it would appear that trimethoprim and sulfamethoxazole may be both efficacious and safe for the treatment of both these infections during pregnancy.

Prolongation of the latency period in preterm premature rupture of the membranes using prophylactic antibiotics and tocolysis

Mixed results have been obtained in several studies using tocolysis or antibiotics individually in the treatment of premature rupture of membranes (PROM). We compared the outcomes of a management protocol consisting of tocolysis, prophylactic antibiotic administration, and documentation of pulmonary maturity with a control group treated with passive expectant management for premature rupture of membranes. There were 55 women in the treatment group and 57 women in the control group. The mean latent phase (+/- SEM) in the treatment group was 7.34 (+/- 1.25) days compared with 1.86 (+/- .431) days in the control group (P less than .001). Eighteen of 55 patients (33%) in the treatment group were electively delivered after documentation of lung maturity, contributing to a falsely lowered mean latent phase in the treatment group. Twenty-four patients in the treatment group and 6 in the control group had a latent phase of 5 days or greater (P = .00018). There were 9 postpartum infections in the control group and 10 infections in the treatment group (P = NS). There was no difference in the length of latent phase of patients treated with ceftizoxime compared with the other antibiotics used (cefoxitin, cefazolin, ampicillin), although postpartum ceftizoxime was more effective in preventing postpartum infections (1 of 28 vs 9 of 27) (P = .005). There were fewer infected neonates in the study group, but this was not significant. It appears that treatment with this protocol significantly prolongs the latent phase in patients with preterm PROM without increasing infectious morbidity.

Transfer of ceftizoxime surpasses that of cefoperazone by the isolated human placenta perfused in vitro

The transfer of cefoperazone and ceftizoxime across the human placenta was compared using the in vitro, bidirectionally perfused human placental lobule. The mean (+/- SEM) clearance indices for ceftizoxime and cefoperazone were 0.124 +/- 0.02 and 0.037 +/- 0.01, respectively (P = .0013). Cefoperazone concentration plateaued at a fetal concentration of 4-5 micrograms/mL in a recirculating perfusion system. No evidence of a decreasing slope of ceftizoxime transfer to the fetal compartment was noted after 60 minutes of perfusion. In a closed-closed perfusion system with equal concentrations of ceftizoxime in each compartment, a 1.1:1 fetal gradient was noted. These data indicate that ceftizoxime crosses the placenta significantly better than does cefoperazone and support our in vivo study documenting preferential concentration of ceftizoxime in the fetal compartment.

17 beta-Hydroxysteroid oxidoreductase activity in human maternal and umbilical cord sera

The specific activity of 17 beta-hydroxysteroid oxidoreductase (17 beta-HSOR) in human umbilical cord arterial serum has been reported to be similar to that of maternal serum and 5- to 15-times higher than that of cord venous serum. Based on these findings, it was proposed that 17 beta-HSOR in cord arterial serum arises from fetal tissue sources other than placenta. In the course of studies of the role of 17 beta-HSOR in the modulation of bioactive estrogen levels in the human fetus, we determined that: (i) the specific activity of 17 beta-HSOR in maternal serum is 2.1- to 55-times higher than that in either umbilical cord venous serum or cord arterial serum; (ii) the specific activity of 17 beta-HSOR in umbilical cord venous and cord arterial sera are similar; (iii) anti-human placental cytosolic 17 beta-HSOR antibody inactivates the 17 beta-HSOR in maternal, umbilical cord arterial, and cord venous sera but not in maternal or fetal erythrocytes; (iv) the specific activity of 17 beta-HSOR in maternal serum (expressed per mg protein) is higher than that in umbilical cord serum and maternal and fetal erythrocytes, and is approximately 700-times lower than that of the placental microsomal enzyme; (v) the preferred cofactor for maternal serum 17 beta-HSOR is NADP+; (vi) 17 beta-HSOR is associated with the high speed supernatant fraction of maternal serum rather than with the particulate fraction; and, (vii) the patterns of binding of [3H]estradiol-17 beta to proteins in maternal and umbilical cord arterial sera and those of 17 beta-HSOR activity, determined in corresponding fractions obtained after sucrose density gradient centrifugation, are approximately coincidental at S20, omega 4.6-5. The findings of higher 17 beta-HSOR levels in maternal serum compared with umbilical cord arterial serum and the inactivation of the cord arterial serum enzyme by an antibody that recognizes human placental cytosolic 17 beta-HSOR is suggestive that 17 beta-HSOR in cord arterial serum is of placental origin.

Effects of platelet activating factor on mouse oocyte fertilization in vitro

Platelet activating factor is rapidly gaining acceptance as a potent mediator in many reproductive processes. This study presents data that indicate a direct role of platelet activating factor in fertilization. Platelet activating factor was shown to significantly increase (p less than 0.001) the fertilization rate of mouse oocytes in vitro. Furthermore, CV3988, an inhibitor of platelet activating factor, was noted to significantly decrease in vitro fertilization rates at 10(-5) and 10(-4) mol/L concentrations.

New technique for stabilizing umbilical artery catheters in very low birthweight infants

The securing of umbilical artery catheters (UACs) with tape bridges has been associated with significant dermal complications in the very low birthweight neonate. We describe a new technique for UAC stabilization using an anchoring adhesive tape applied directly to the catheter, which is in turn sutured to the cord. This technique provides a very satisfactory method of UAC stabilization and avoids skin complications associated with the standard methods.

Determination of pentamidine transfer in the in vitro perfused human cotyledon with high-performance liquid chromatography

Pentamidine is used to treat Pneumocystis carinii pneumonia. The incidence of this infection in pregnancy has paralleled the increasing incidence of acquired immunodeficiency syndrome in pregnancy. Using the in vitro bidirectionally perfused human placenta, we studied the transfer of pentamidine across the placenta. Pentamidine was added to the maternal circulation at therapeutic concentrations (2 micrograms/ml). No transfer of pentamidine was detectable with a newly devised high-performance liquid chromatography method sensitive to 0.05 micrograms/ml of pentamidine. Increasing the pentamidine concentration tenfold produced a low level of transfer to the fetal circuit. Fetal concentrations were far below maternal perfusate concentrations. Placental tissue levels were higher than media levels. These data are suggestive of minimal drug transfer to the fetus and significant concentration of the drug in placental tissue.

Placental transfer of cefoperazone and sulbactam in the isolated in vitro perfused human placenta

The transfer of cefoperazone and sulbactam across the human placenta was studied qualitatively and quantitatively with the isolated in vitro bidirectionally perfused human placental lobule. Clearance indexes for both cefoperazone and sulbactam were derived. The absence of active transport and facilitated diffusion were documented, implying simple diffusion as the mechanism of placental transfer for both drugs. Placental tissue levels were also studied.

Steady-state cord and amniotic fluid ceftizoxime levels continuously surpass maternal levels

As part of our management protocol for preterm premature rupture of membranes, ceftizoxime and tocolysis were used to prolong the latent period and prevent or treat concomitant infection. Ceftizoxime was selected for this protocol based on its physiochemical properties, which favor placental transfer of the drug. Patients achieving steady-state pharmacodynamics (more than three doses of the drug) were considered eligible for study. Ceftizoxime levels were determined by reverse-phase high-pressure liquid chromatography. All levels measured after the first hour of treatment were indicative of the relative concentration of ceftizoxime in the fetal and amniotic fluid compartments when compared with the maternal compartment. Mean (+/- SEM) ceftizoxime levels were 11.96 + 2.35 micrograms/ml in maternal serum, 24.54 +/- 4.78 micrograms/ml in cord serum, and 43.45 +/- 4.97 micrograms/ml in amniotic fluid. Based on its broad antibacterial activity and its high concentration in fetal blood and amniotic fluid, ceftizoxime appears to be an ideal agent for treatment of the intrauterine environment.

External cephalic version with tocolysis: factors associated with success

Data were collected prospectively on factors that might affect the success or failure of external cephalic version, using a protocol including fetal monitoring, ultrasound, tocolysis, and external version after 37 weeks' gestation. Patients were accepted into the protocol whether or not risk factors for failure were present. Sixty-seven patients were admitted to the study and 40 (60%) underwent successful version. Using chi 2 analysis, we found that failure of external version was significantly associated with obesity, descent of the breech into the pelvis, decreased fluid, and fetal back positioned posteriorly. Thirteen women were in active labor; this had no effect on the success rate providing that descent had not occurred. Two factors, descent of the breech into the pelvis and posterior position of the fetal back, had an independent effect on success after controlling for other variables.

Continuous subcutaneous insulin infusion during pregnancy

The development of battery-powered pumps for continuous subcutaneous insulin infusion added new dimensions to control of diabetes during pregnancy. In this report, we describe our experiences with 28 pregnant diabetic women offered participation in an insulin pump program. Fifteen (54%) accepted pump therapy and ten continued usage during their pregnancies. Excluding abortions, eight women continuing pump use are compared to 11 others who declined such therapy and were treated with conventional methods. Although these two groups are small and not strictly comparable, the experiences now reported provide clinical insights into the application of this new technology during pregnancy. Women who successfully used insulin pumps were typically from the private sector and in better glucose control at study entry. The degree of control during pregnancy in women using pumps was not significantly different compared to conventional glucose control methods (mean glucose 120 mg/dl and 142 mg/dl, respectively). Similarly, several indices of pregnancy outcome including length of hospitalization, costs, and perinatal morbidity associated with diabetes were analyzed and no significant differences were observed. We conclude that insulin pumps are not acceptable to all pregnant diabetic women and that such therapy may not necessarily improve pregnancy outcome.

Apolipoprotein A-1 in umbilical cord blood of newborn infants: relation to gestational age and high-density lipoprotein cholesterol

Apolipoprotein A-1 (Apo A-1) is the major protein constituent of high-density lipoprotein (HDL) and Apo A-1 plays an important role in lipid metabolism and may be protective against atherosclerosis in adults. However, little is known about HDL and Apo A-1 in the developing human fetus. Herein we investigated the relationship of Apo A-1 levels in umbilical cord blood at delivery to gestational age and HDL cholesterol. Fetal plasma levels of Apo A-1, which were not correlated with those in maternal plasma, were significantly lower among newborns delivered at 21-26 wk gestation (52 +/- 4.4 mg/dl, mean +/- SE) than in those delivered at 33-34 wk gestation (87 +/- 5.8 mg/dl). Thereafter, the mean umbilical cord plasma levels of Apo A-1 remained relatively constant (101 mg/dl at 39-40 wk of gestation). We found no significant correlations between Apo A-1 levels and fetal sex, race, or delivery method. At equivalent gestational ages and birth weights, however, Apo A-1 levels in white newborns tended to be lower than those in black infants. The Apo A-1/HDL cholesterol ratio in umbilical cord blood rose progressively from 2.5 (27-28 wk gestation) to 3.8 at term, due largely to increased Apo A-1 levels but little change in the mean HDL cholesterol levels, which ranged from 22-24 mg/dl at each gestational period. These results are suggestive that fetal plasma Apo A-1 is derived solely from fetal sources and that the rate of production and/or clearance of Apo A-1 is altered during the latter third of human intrauterine development.

Microorganisms and premature labor

A number of organisms, including Mycoplasma, group B Streptococcus, Bacteroides, Neisseria gonorrhoeae and Chlamydia trachomatis, have been isolated more frequently from patients in premature labor than from controls. Prophylactic antibiotic treatment in some studies lowered the incidence of prematurity. Silent chorioamnionitis has been noted in 15% of patients in premature labor. Untreated pyelonephritis is clearly associated with premature labor; however, the association of asymptomatic bacteriuria, appropriately treated pyelonephritis and premature labor is less clear. Some microorganisms have been demonstrated to produce phospholipase A2 and possibly prostaglandins, which might be the mechanism for some of the associations between premature labor and bacteria.

Therapeutic considerations in postpartum endometritis

The physiologic changes of pregnancy and the puerperium and their effect on antibiotic therapy have not received widespread attention. Pregnancy is accompanied by multiple physiologic changes, including increased uterine weight, blood volume, extracellular fluid, endometrial blood flow and renal function changes. Those changes affect therapy for endometritis since it may take several weeks for a return to the pregravid state. Preeclampsia is associated with reductions in intravascular space, increased extravascular space from edema and impaired renal function. Postpartum uterine changes may also complicate drug therapy because of poor antibiotic perfusion. The ideal antibiotic for postpartum endometritis would achieve optimal uterine tissue levels, be administered infrequently, and have adequate activity against anaerobes and minimal toxicity.

Prolactin response to perphenazine. A sensitive and specific test for pituitary tumor in hyperprolactinemic women

A simple biochemical screening test for prolactin-secreting pituitary tumors is needed because computed tomography is expensive and may be insensitive in the detection of microadenomas. We compared serial prolactin levels following perphenazine stimulation in 20 women with histologically documented tumors to those in 22 normal controls. In addition, seven women who were diagnosed as having functional (nontumor) hyperprolactinemia were tested. All subjects were given perphenazine, 8 mg orally. Baseline and hourly serum prolactins for six hours were compared. A 200% or greater response occurred in all control patients and functional hyperprolactinemic subjects within six hours following medication. Without exception, tumor patients exhibited a markedly blunted or absent response. This markedly diminished response pattern was compatible with the presence of a pituitary adenoma and suggests that the presence of a tumor interferes with normal pituitary secretory responsiveness.