Continuous versus cyclic use of combined oral contraceptives for contraception: systematic Cochrane review of randomized controlled trials

BACKGROUND

With the recent US Food and Drug Administration approval of a combination oral contraceptive that causes a withdrawal bleed every 3 months instead of monthly, avoidance of menstruation through extended or continuous administration (>28 days of active pills) of combined oral contraceptives may become more commonplace for reasons of personal preference rather than limited to treatment of menstrual-associated medical disorders.

METHODS

The review aimed to compare contraceptive efficacy, compliance, continuation, satisfaction, bleeding profiles, and menstrual symptoms of combined oral contraceptives with continuous dosing (>28 days of active pills) versus traditional cyclic dosing (21 days of active pills and 7 days of placebo). We searched five computerized databases as well as reference lists of relevant articles for randomized controlled trials (RCT) using continuous or extended combined oral contraceptives for contraception. Two reviewers independently extracted data from eligible articles.

RESULTS

Six RCT met inclusion criteria and were of good quality. Contraceptive efficacy and compliance were similar between groups. Discontinuation overall, and for bleeding problems, was not uniformly higher in either group. When studied, participants reported high satisfaction with both dosing regimens. Five out of the six studies found that bleeding patterns were either equivalent or improved with continuous-dosing regimens. The continuous-dosing group had greater improvement of menstrual-associated symptoms (headaches, genital irritation, tiredness, bloating, and menstrual pain).

CONCLUSIONS

The variations in pill type and time-interval for continuous dosing make direct comparisons between regimens unfeasible. To allow for comparisons, future studies should choose a previously researched pill and dosing regimen. More attention needs to be directed towards participant satisfaction and menstruation-associated symptoms.

Comparing the acceptability of manual vacuum aspiration and electric vacuum aspiration as methods of early abortion

OBJECTIVE

to compare the acceptability of manual vacuum aspiration (MVA) and electric vacuum aspiration (EVA) as methods of early (< or = 77 days' gestation) abortion.

METHODS

We interviewed 42 women who had been randomly assigned to either MVA or EVA and compared their perceptions of the two procedures.

RESULTS

The experiences and perceptions of women in the two groups were similar in many ways. The majority of women in both procedure groups were very satisfied with the method used, and most indicated that they would prefer the same method if they were to have another abortion.

CONCLUSION

This study found no major differences in the acceptability of MVA and EVA among women undergoing early abortions.

Regulation of ClC-2 chloride channels in T84 cells by TGF-α

The almost ubiquitously expressed ClC-2 chloride channel is activated by hyperpolarization and osmotic cell swelling. Osmotic swelling also activates a different class of outwardly rectifying chloride channels, and several reports point to a link between protein tyrosine phosphorylation and activation of these channels. This study examines the possibility that transforming growth factor-α (TGF-α) modulates ClC-2 activity in human colonic epithelial (T84) cells. TGF-α (0.17 nM) irreversibly inhibited ClC-2 current in nystatin-perforated whole cell patch-clamp experiments, whereas a superimposed reversible activation of the current was observed at 8.3 nM TGF-α. Both effects required activation of the intrinsic epidermal growth factor receptor (EGFR) tyrosine kinase activity, of phosphoinositide 3-kinase, and of protein kinase C. With microspectrofluorimetry of the pH-sensitive fluorescent dye 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, TGF-α was shown to reversibly alkalinize T84 cells at 8.3 nM but not at 0.17 nM, suggesting that 8.3 nM TGF-α-induced alkalinization activates ClC-2 current. This study indicates that ClC-2 channels are targets for EGFR signaling in epithelial cells.

Comparison of pain and time of procedures with two first-trimester abortion techniques performed by residents and faculty

OBJECTIVES

We compared pain perception and procedure time in abortions performed by residents and faculty using a manual vacuum aspirator and electric vacuum curettage devices.

STUDY DESIGN

We conducted a randomized trial of 114 women undergoing first-trimester abortions. Patients assessed the level of pain with visual analog scales.

RESULTS

The mean procedure times were 5.7 and 6.9 minutes, respectively, with electric vacuum curettage and manual vacuum aspirator. Faculty took less time than residents to perform both procedures. Patients reported a higher pain level with cervical dilatation before resident electric vacuum curettage procedures. Patients undergoing electric vacuum curettage thought that the procedure noise increased their pain.

CONCLUSIONS

First-trimester abortion procedures can be performed more quickly by experienced surgeons. The procedure time for the manual vacuum aspirator is greater than that for the electric vacuum curettage. Patient pain perception with aspiration by these two techniques is not different. The level of pain after aspiration did not vary significantly in patients who had abortions performed by residents or faculty.

Two mild cystic fibrosis-associated mutations result in severe cystic fibrosis when combined in cis and reveal a residue important for cystic fibrosis transmembrane conductance regulator processing and function

The number of complex cystic fibrosis transmembrane conductance regulator (CFTR) genotypes identified as having double-mutant alleles with two mutations inherited in cis has been growing. We investigated the structure-function relationships of a severe cystic fibrosis (CF)-associated double mutant (R347H-D979A) to evaluate the contribution of each mild mutation to the phenotype. CFTR mutants expressed in HeLa cells were analyzed for protein biosynthesis and Cl(-) channel activity. Our data show that R347H is associated with mild defective Cl(-) channel activity and that the D979A defect leads to misprocessing. The mutant R347H-D979A combines both defects for a dramatic decrease in Cl(-) current. To decipher the molecular mechanism of this phenotype, single and double mutants with different charge combinations at residues 347 and 979 were constructed as charged residues were involved in this complex genotype. These studies revealed that residue 979, located in the third cytoplasmic loop, is critical for CFTR processing and Cl(-) channel activity highlighting the role of charged residues. These results have also important implications for CF, as they show that two mutations in cis can act in concert to alter dramatically CFTR function contributing to the wide phenotypic variability of CF disease.

NF-kappa B mediates up-regulation of CFTR gene expression in Calu-3 cells by interleukin-1beta

Inflammation of the airways is a major feature of the inherited disease cystic fibrosis. Previous studies have shown that the pro-inflammatory cytokines tumor necrosis factor alpha and interferon gamma reduce the expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene (CFTR) in HT-29 and T84 cells by acting post-transcriptionally. We have investigated the effect of the pro-inflammatory peptide interleukin 1beta (IL-1beta) on the expression of the CFTR in Calu-3 cells. IL-1beta increased the production of CFTR mRNA in a dose- and time-dependent manner. Its action was inhibited by inhibitors of the NF-kappaB pathway, including N-acetyl-l-cysteine, pyrrolidine dithiocarbamate, and a synthetic cell-permeable peptide containing the NF-kappaB nuclear localization signal sequence. Gel shift analysis showed that IL-1beta activated NF-kappaB in Calu-3 cells, and transfection experiments using p50 and RelA expressing vectors showed that exogenous transfected NF-kappaB subunits increased the concentration of CFTR mRNA. Gel shift analysis with antibody supershifting also showed that IL-1beta caused the binding of NF-kappaB to a kappaB-like response element at position -1103 to -1093 in the CFTR 5'-flanking region. Transfection experiments using -2150 to +52 CFTR reporter gene constructs showed that the activity of the CFTR promoter is enhanced by exogenous transfected NF-kappaB and IL-1beta and that this enhancement is due, at least in part, to the -1103 to -1093 kappaB site. We conclude that the intracellular signaling that leads to increased CFTR mRNA in response to IL-1beta in Calu-3 cells includes the binding of NF-kappaB to the -1103 kappaB element and a subsequent increase in CFTR promoter activity.

Drug resistance induced by ouabain via the stimulation of MDR1 gene expression in human carcinomatous pulmonary cells

The inhibition of the Na+/K+-ATPase by cardiotonic drugs like ouabain deeply perturbs both the properties of the cell membrane and the ionic composition of the cytoplasm and hence alters fundamental cell reactions. These three types of reactions may be involved in the stimulation of multidrug resistance 1 (MDR-1) gene expression and the synthesis of permeability glycoprotein [P-glycoprotein (P-gp)]. We have determined whether ouabain, which binds to an extracellular motif of the Na+/K+-ATPase, stimulates MDR-1 gene expression by measuring both mRNA and protein and whether the resulting P-gp extrudes hydrophobic compounds and causes resistance to antimitotic agents. The experiments were performed on Calu-3 cells, a human cell line from a pulmonary carcinoma. Northern blotting showed that treating the cells with submicromolar concentrations of ouabain stimulated MDR-1 gene expression within 24 h. The ouabain-induced stimulation of MDR-1 expression was not restricted to Calu-3 cells but also occurred in human carcinomatous colon (T-84 and HT-29) and hepatic (H7V3) cells. However, it is not ubiquitous because it was not found in HeLa cells. The stimulation was reproduced by other Na+/K+-ATPase inhibitors and occurred via enhanced gene transcription, apparently due to the increased cytosolic calcium concentration. Ouabain also increased the membrane content of P-gp, as detected by immunoblotting and immunohistology. We have developed a microvideo assay based on the properties of acetoxymethyl ester calcein and calcein to show that this P-gp extruded the hydrophobic acetoxymethyl ester calcein. Ouabain also caused the Calu-3 cells to become resistant to doxorubicin and vinblastine. Thus, although ouabain acts extracellularly, it may stimulate MDR-1 gene expression and P-gp synthesis and make cells resistant to hydrophobic cytotoxic compounds.

Functional cystic fibrosis transmembrane conductance regulator tagged with an epitope of the vesicular stomatis virus glycoprotein can be addressed to the apical domain of polarized cells

The cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation-activated chloride channel apically localized in epithelial cells. In cystic fibrosis patients, the gene encoding this N-linked glycoprotein is mutated. About 70% of CF patients express a mutated form of CFTR, deleted at the phenylalanine residue at position 508 (deltaF508). CFTR-deltaF508 fails to exit the endoplasmic reticulum; it remains incompletely glycosylated and is rapidly degraded. To optimize CFTR detection for membrane localization studies and biochemical studies, we tagged wild-type and deltaF508 CFTR with the VSV-G epitope at their carboxy-terminal ends. We have generated pig kidney epithelial cell clones (LLCPK1) expressing VSV-G-tagged human wild-type and deltaF508-CFTR. In CFTR-expressing cells, the transfected protein is maturated and transported to the apical membrane where it is concentrated. The cells exhibit a strong anion channel activity after stimulation by cAMP, as demonstrated by a halide sensitive fluorescent dye assay (6-methoxy-N-ethylquinominium, SPQ), and whole-cell patch-clamp approach. This activity of CFTR-VSV-G is indistinguishable from the wild-type CFTR. In contrast, in cells expressing tagged deltaF508-CFTR or in non-transfected cells, no anion channel activity could be detected after stimulation by cAMP. In deltaF508-CFTR-VSV-G-expressing cells, the mutated CFTR remained in the incompletely glycosylated form and was localized in the endoplasmic reticulum. These cell lines reproduce the cellular fate of wild-type and mutated CFTR-deltaF508. To our knowledge, they are the first differentiated epithelial cell lines stably expressing tagged CFTR and CFTR-deltaF508 in which cellular processing and functional activity of these two proteins are reproduced. Thus the addition of the VSV-G epitope does not impair the localization and function of CFTR, and these cell lines can be used to examine CFTR function in vitro.

Modulation of CFTR gene expression in HT-29 cells by extracellular hyperosmolarity

Hypertonicity has pleiotropic effects on cell function, including activation of transporters and regulation of gene expression. It is important to investigate the action of hypertonicity on cystic fibrosis gene expression because cystic fibrosis transmembrane conductance regulator (CFTR), the cAMP-regulated Cl(-) channel, regulates ion transport across the secretory epithelia, which are often in a hypertonic environment. We found that adding >150 mosmol/l NaCl, urea, or mannitol to the culture medium reduced the amount of CFTR mRNA in colon-derived HT-29 cells in a time-dependent manner. Studies with inhibitors of various kinases [H-89 (protein kinase A inhibitor), bisindolylmaleimide (protein kinase C inhibitor), staurosporine (serine/threonine kinase inhibitor) and herbimycin A (tyrosine kinase inhibitor), SB-203580 and PD-098059 (mitogen-activated protein kinase inhibitors)] showed that CFTR gene expression and its decrease by added NaCl required p38 kinase cascade activity. The CFTR gene activity is regulated at the transcriptional level, since adding NaCl diminished the luciferase activity of HeLa cells transiently transfected with the CFTR promoter. This regulation requires protein synthesis. The complexity of the reactions involved in blocking CFTR gene transcription by NaCl strongly suggests that the decrease in CFTR mRNA is part of a general cell response to hyperosmolar stress.

Ammonium transport by the colonic H(+)-K(+)-ATPase expressed in Xenopus oocytes

Functional expression of the rat colonic H(+)-K(+)-ATPase was obtained by coexpressing its catalytic alpha-subunit and the beta(1)-subunit of the Na(+)-K(+)-ATPase in Xenopus laevis oocytes. We observed that, in oocytes expressing the rat colonic H(+)-K(+)-ATPase but not in control oocytes (expressing beta(1) alone), NH(4)Cl induced a decrease in (86)Rb uptake and the initial rate of intracellular acidification induced by extracellular NH(4)Cl was enhanced, consistent with NH(+)(4) influx via the colonic H(+)-K(+)-ATPase. In the absence of extracellular K(+), only oocytes expressing the colonic H(+)-K(+)-ATPase were able to acidify an extracellular medium supplemented with NH(4)Cl. In the absence of extracellular K(+) and in the presence of extracellular NH(+)(4), intracellular Na(+) activity in oocytes expressing the colonic H(+)-K(+)-ATPase was lower than that in control oocytes. A kinetic analysis of (86)Rb uptake suggests that NH(+)(4) acts as a competitive inhibitor of the pump. Taken together, these results are consistent with NH(+)(4) competition for K(+) on the external site of the colonic H(+)-K(+)-ATPase and with NH(+)(4) transport mediated by this pump.

Structure-function analysis of a double-mutant cystic fibrosis transmembrane conductance regulator protein occurring in disorders related to cystic fibrosis

A number of disorders related to cystic fibrosis have been described since the cloning of the cystic fibrosis gene, including infertility due to the congenital bilateral absence of the vas deferens. We have identified, in several patients, complex cystic fibrosis transmembrane conductance regulator genotypes like double-mutant alleles. We have now analyzed the structure-function relationships of one of these mutants, R74W-D1270N cystic fibrosis transmembrane conductance regulator, expressed in HeLa cells, to evaluate the contribution of each mutation in the phenotype. We found that R74W cystic fibrosis transmembrane conductance regulator appears to be a polymorphism, while D1270N cystic fibrosis transmembrane conductance regulator could be responsible for the congenital bilateral absence of the vas deferens phenotype. The combination of the two produced a more severe effect on the chloride conductance pathway as well as on the phenotype.

Aspirin and some other nonsteroidal anti-inflammatory drugs inhibit cystic fibrosis transmembrane conductance regulator protein gene expression in T-84 cells

Cystic fibrosis (CF) is caused by mutations in the CF gene, which encodes CF transmembrane conductance regulator protein (CFTR), a transmembrane protein that acts as a cAMP-regulated chloride channel The disease is characterized by inflammation but the relationship between inflammation, abnormal transepithelial ion transport, and the clinical manifestations of CF are uncertain. The present study was undertaken to determine whether three nonsteroidal anti-inflammatory drugs (NSAIDs) (aspirin, ibuprofen, and indomethacin) modulate CFTR gene expression in T-84 cells. Treatment with NSAIDs reduced CFTR transcripts, and decreased cAMP-stimulated anion fluxes, an index of CFTR function. However, the two phenomena occurred at different concentrations of both drugs. The results indicate that NSAIDs can regulate both CFTR gene expression and the function of CFTR-related chloride transport, and suggest that NSAIDs act via multiple transduction pathways.

New sequence-specific human ribonuclease: purification and properties

A new sequence-specific RNase was isolated from human colon carcinoma T84 cells. The enzyme was purified to electrophoretical homogeneity by pH precipitation, HiTrapSP and Superdex 200 FPLC. The molecular weight of the new enzyme, which we have named RNase T84, is 19 kDa. RNase T84 is an endonuclease which generates 5'-phosphate-terminated products. The new RNase selectively cleaved the phosphodiester bonds at AU or GU steps at the 3' side of A or G and the 5' side of U. 5'AU3' or 5'GU3' is the minimal sequence required for T84 RNase activity, but the rate of cleavage depends on the sequence and/or structure context. Synthetic ribohomopolymers such as poly(A), poly(G), poly(U) and poly(C) were very poorly hydrolysed by T84 enzyme. In contrast, poly(I) and heteroribopolymers poly(A,U) and poly(A,G,U) were good substrates for the new RNase. The activity towards poly(I) was stronger in two colon carcinoma cell lines than in three other epithelial cell lines. Our results show that RNase T84 is a new sequence-specific enzyme whose gene is abundantly expressed in human colon carcinoma cell lines.