Tenofovir, emtricitabine, lamivudine and dolutegravir concentrations in plasma and urine following drug intake cessation in a randomized controlled directly observed pharmacokinetic trial to aid point-of-care testing

BACKGROUND

Poor adherence to ART and pre-exposure prophylaxis (PrEP) can impact patient and public health. Point-of-care testing (POCT) may aid monitoring and adherence interventions.

OBJECTIVES

We report the pharmacokinetics of tenofovir [dosed as tenofovir disoproxil (TDF) and tenofovir alafenamide (TAF)], emtricitabine (FTC), lamivudine (3TC) and dolutegravir (DTG) in plasma and urine following drug cessation to evaluate adherence targets in urine for POCT.

METHODS

Subjects were randomized (1:1) to receive DTG/FTC/TAF or DTG/3TC/TDF for 15 days. Plasma and spot urine were collected on Day 15 (0-336 h post final dose). Drug concentrations were quantified using LC-MS, and non-linear mixed-effects models applied to determine drug disposition between matrices and relationship with relevant plasma [dolutegravir protein-adjusted 90% inhibitory concentration (PA-IC90 = 64 ng/mL) and minimum effective concentration (MEC = 324 ng/mL)] and urinary thresholds [tenofovir disoproxil fumarate 1500 ng/mL].

RESULTS

Of 30 individuals enrolled, 29 were included (72% female at birth, 90% Caucasian). Median (range) predicted time to plasma dolutegravir PA-IC90 and MEC were 83.5 (41.0-152) and 49.0 h (23.7-78.9), corresponding to geometric mean (90%) urine concentrations of 5.42 (4.37-6.46) and 27.4 ng/mL (22.1-32.7). Tenofovir in urine reached 1500 ng/mL by 101 h (58.6-205) with an equivalent plasma concentration of 6.20 ng/mL (4.21-8.18).

CONCLUSIONS

These data support use of a urinary tenofovir threshold of <1500 ng/mL (tenofovir disoproxil fumarate-based regimens) as a marker of three or more missed doses for a POCT platform. However, due to low dolutegravir concentrations in urine, POCT would be limited to a readout of recent dolutegravir intake (one missed dose).

Dysregulated wound healing in the pathogenesis of urogynecologic mesh complications

To test the hypothesis that dysregulated wound healing is associated with Urogynecologic mesh complications, we collected vaginal cell secretions using vaginal swabs after polypropylene mesh implantation in patients with (N = 39) and without (N = 40) complication. A customized multiplex immunoassay measured markers of inflammation (MCP-1, IGFBP-1, IL-2, IL-10, IL-17, PDGF-BB, bFGF, IL-1b, IL-6, IL-12p70, TNF-α), neuroinflammation (IL-1RA, TGF-β, IL-15, IL-18, IL-3, M-CSF), angiogenesis (VEGF), and matrix proteins (fibronectin, tenasin c, thrombospondin-2, lumican) between groups. Patients with complications were younger, heavier, implanted with mesh longer, and more likely to be ever smokers. A 5 kg/m2 BMI increase and ever-smoking were associated with a 2.4-fold and sixfold increased risk of complication, respectively. Patients with the highest tertile of bFGF, fibronectin, thrombospondin-2, TNF-β, or VEGF had an odds ratio (OR) of 11.8 for having a mesh complication while ≥ 3 elevated had an OR of 237 while controlling for age, BMI, and smoking. The highest tertile of bFGF, thrombospondin-2, and fibronectin together perfectly indicated a complication (P < 0.0001). A receiver-operator curve for high bFGF, thrombospondin-2, and fibronectin showed excellent discrimination between complications and controls (AUC 0.87). These data provide evidence of dysregulated wound healing in mesh complications. Modifiable factors provide potential targets for patient counseling and interventions.

A topical rectal douche product containing Q-Griffithsin does not disrupt the epithelial border or alter CD4+ cell distribution in the human rectal mucosa

To reduce HIV transmission, locally applied pre-exposure prophylaxis (PrEP) products for anorectal use will be important complements to oral and injectable PrEP products already available. It is critical to preserve an intact rectal epithelium and avoid an influx of mucosal HIV target cells with such product use. In this phase 1 clinical trial, we evaluated application of a topical rectal douche product containing Q-Griffithsin (Q-GRFT). Colorectal tissue samples were obtained via sigmoidoscopy at baseline, 1 and 24 h after single-dose exposure in 15 healthy volunteers. In situ staining for epithelial junction markers and CD4⁺ cells were assessed as an exploratory endpoint. A high-throughput, digitalized in situ imaging analysis workflow was developed to visualize and quantify these HIV susceptibility markers. We observed no significant differences in epithelial distribution of E-cadherin, desmocollin-2, occludin, claudin-1, or zonula occludens-1 when comparing the three timepoints or Q-GRFT versus placebo. There were also no differences in %CD4⁺ cells within the epithelium or lamina propria in any of these comparisons. In conclusion, the rectal epithelium and CD4⁺ cell distribution remained unchanged following topical application of Q-GRFT. In situ visualization of HIV susceptibility markers at mucosal sites could be useful to complement standard product safety assessments.

Characterization of vaginal immune response to a polypropylene mesh: Diabetic vs. normoglycemic conditions

OBJECTIVE

Urogynecology meshes, typically manufactured from polypropylene, are widely used in the surgical treatment of stress urinary incontinence and pelvic organ prolapse. However, mesh-associated complications such as mesh exposure can develop in women undergoing mesh implantation, for which diabetes is an independent risk factor. We aimed to define the impact of diabetes on the vaginal immune response to mesh by comparing diabetic vs. normoglycemic conditions longitudinally in a rat sacrocolpopexy model.

METHODS

Diabetes (blood glucose ≥ 300 mg/dL) was induced in middle-aged female Wistar rats with streptozotocin (STZ). A polypropylene mesh was implanted on the vagina via modified sacrocolpopexy following bilateral ovariectomy and supracervical hysterectomy for 3-, 7-, and 42-days. Sham-operated controls underwent the same procedures without mesh. Mesh-associated inflammation, immune cell populations and cytokine/chemokine profiles were examined in the excised vaginal tissues.

RESULTS

Diabetes was reliably induced starting on the 3rd day following STZ injection. Under both normoglycemic and diabetic conditions, mesh caused a prolonged inflammatory response in the vagina with increased proinflammatory chemokines MCP-1 and MIP-1α as compared to Sham. Major differences between the two conditions were found at the later stage (42 days post-surgery), including an increased inflammation with larger foreign body granuloma and more giant cells at the mesh-tissue interface, increased fraction of macrophages in the immune cell population, and higher proinflammatory chemokine IP-10 in the diabetic group.

CONCLUSION

Polypropylene mesh implanted on the vagina induces prolonged inflammation at the mesh-tissue interface. Diabetes increases the mesh-associated inflammation in the long term, which is related to a dysregulated macrophage response.

STATEMENT OF SIGNIFICANCE

This study investigated the mechanism underlying the increased risk in women with diabetes for developing mesh complications such as mesh exposure. The significance includes: (1) it is the first study investigating vaginal host response to a prosthesis under the influence of diabetes; (2) the longitudinal study design elucidated the dynamic changes of vaginal immune response to mesh from very early to late stages; (3) our findings may inform future mechanistic studies and studies investigating preventive/therapeutic strategies to improve the outcomes of women with diabetes receiving vaginal implants.

Symptomatic improvement after mesh removal: a prospective longitudinal study of women with urogynaecological mesh complications

OBJECTIVE

To compare clinical characteristics and outcomes in patients undergoing excision of polypropylene urogynaecological mesh for pain, mesh exposure or both.

DESIGN

Prospective, longitudinal cohort.

SETTING

Academic tertiary referral centre.

POPULATION

Women undergoing complete vaginal mesh excision for mesh exposure and/or pain.

METHODS

Clinical and patient-reported outcomes assessing pain (visual analog scale, VAS), bother (Pelvic Floor Distress Inventory, PFDI) and functional impact (Pelvic Functional Impact Questionnaire, PFIQ) were collected at baseline, 6, 12 and 24 months after complete mesh excision. Outcomes were compared by mesh type (sling, prolapse [transvaginal or sacrocolpopexy mesh], both) and complication (pain, exposure, both).

MAIN OUTCOME MEASURES

'Much better' or 'Very much better' on Patient Global Impression of Improvement (PGI-I) up to 2 years after removal.

RESULTS

Of 173 women, 48 underwent removal for pain, 27 for exposure and 98 for exposure plus pain. 'Moderate to severe' baseline symptoms were reported by 75%; the most prevalent and severe symptom was dyspareunia. Patients with pain alone were most bothered (PFDI median 234.2, interquartile range 83, P = 0.02) and had the highest functional impact (PFIQ median 181, interquartile range 138, P < 0.001). After excision, only 33.3% of women with pain alone reported 'improved' symptoms (PGI-I), versus 73.9% with exposure, 58.3% with exposure plus pain (P = 0.03) with no differences in PGI-I by mesh type. VAS scores decreased in all groups, but PFDI and PFIQ did not improve in pain patients.

CONCLUSIONS

In women experiencing a pain complication after urogynaecological mesh insertion, mesh removal often does not improve symptoms.

TWEETABLE ABSTRACT

Only 33% of women with pain complications have improved symptoms after urogynaecological mesh removal.

A Phase 2, Randomized, Control Trial of Group B Streptococcus (GBS) Type III Capsular Polysaccharide-tetanus Toxoid (GBS III-TT) Vaccine to Prevent Vaginal Colonization With GBS III

BACKGROUND

Group B Streptococcus (GBS) frequently colonizes pregnant women and can cause sepsis and meningitis in young infants. If colonization was prevented through maternal immunization, a reduction in perinatal GBS disease might be possible. A GBS type III capsular polysaccharide (CPS)-tetanus toxoid conjugate (III-TT) vaccine was evaluated for safety and efficacy in preventing acquisition of GBS colonization.

METHODS

Healthy, nonpregnant women aged 18-40 years and screened to be GBS III vaginal and rectal culture negative were randomized to receive III-TT conjugate or tetanus diphtheria toxoid vaccine in a multicenter, observer-blinded trial. GBS vaginal and rectal cultures and blood were obtained bimonthly over 18 months. Serum concentrations of GBS III CPS-specific antibodies were determined using enzyme-linked immunosorbent assay.

RESULTS

Among 1525 women screened, 650 were eligible for the intent-to-treat analysis. For time to first acquisition of vaginal GBS III, vaccine efficacy was 36% (95% confidence interval [CI], 1%-58%; P = .044), and for first rectal acquisition efficacy was 43% (95% CI, 11% to 63%; P = .014). Two months post-immunization, geometric mean concentrations of serum GBS type III CPS-specific immunoglobulin G were 12.6 µg/mL (95% CI, 9.95 to 15.81) in GBS III-TT recipients, representing a 4-fold increase from baseline in 95% of women, which persisted. Both vaccines were well tolerated.

CONCLUSIONS

GBS CPS III-TT conjugate vaccine significantly delayed acquisition of vaginal and rectal GBS III colonization. In addition to its use for maternal immunization to passively protect infants with maternally derived antibodies, a multivalent vaccine might also serve to reduce fetal and neonatal exposure to GBS.

CLINICAL TRIALS REGISTRATION

NCT00128219.

Mesh induced fibrosis: The protective role of T regulatory cells

Polypropylene mesh is widely used in urogynecologic surgery, but complications rates (pain and exposure) approach 10%. Emerging evidence implicates the adaptive immune system in regulating the foreign body response to mesh, particularly regulatory T cells (T_regs), which modify macrophage differentiation and down-regulate CD8⁺ effector T cells. We hypothesize that T_regs protect against a profibrotic response, a likely mechanism of pain complications. Here, thin sections of mesh-tissue complexes removed for the primary complaint of pain (N = 14) or exposure (N = 15) were labeled for CD8, CD4 (T_h), and FoxP3 (T_regs) via immunofluorescence. The same sections were analyzed for localized collagen deposition via a customized semi-quantitative assessment (0.25 mm² grid) after trichrome staining. TGF-β1 concentrations were determined by enzyme-linked immunosorbent assay. Fewer T_reg and CD4⁺ cells were found in fibrotic areas versus non-fibrotic areas (503 and 550/cm² fewer, respectively, both P < 0.001). TGF-β1 was higher in mesh samples compared to autologous control biopsies. TGF-β 1 inversely correlated with age, r -0.636(p = 0.008). No differences were found in T cell subgroups or fibrotic indices between pain and exposure groups. A moderate inverse relationship was found between TGF-β1 and T_regs (r -0.402, P = 0.009)_. T_regs were present up to 12 years after mesh implantation, challenging the assumption that the adaptive immune response to a foreign body is transient. In conclusion, the inverse relationship between fibrosis and T_regs, and TGF-β1 and T_regs points to a protective role of these cells. Similar immunologic responses in patients with pain and exposure suggest these complications exist along a spectrum. STATEMENT OF SIGNIFICANCE: The use of polypropylene mesh has been associated with improved outcomes in urogynecologic surgery, but is associated with significant complications, including pain and exposure through the vaginal epithelium. The host immune response features a prolonged inflammatory reaction containing innate immune cells and T lymphocytes clustered in capsules around the mesh fibers. This study uncovers the inverse relationship between T regulatory cells and the extent of fibrosis around the mesh, suggesting an anti-fibrotic effect. In addition, concentrations of T regulatory and T effector cells and levels of fibrosis connect these two most common complications into one mechanistic pathway. These new insights into the immune response to implanted mesh are an important step in understanding the causes of these surgical complications.

Characterization of the T-cell response to polypropylene mesh in women with complications

BACKGROUND

Polypropylene mesh is used widely for surgical treatment of pelvic organ prolapse and stress urinary incontinence. Although these surgeries demonstrate favorable functional and anatomic outcomes, their use has been limited by complications, the 2 most common being exposure and pain. Growing evidence suggests that T lymphocytes play a critical role in the regulation of the host response to biomaterials.

OBJECTIVE

The purpose of this study was to define and characterize the T-cell response and to correlate the response to collagen deposition in fibrotic capsules in mesh tissue complexes that are removed for the complications of pain vs exposure.

STUDY DESIGN

Patients who were scheduled to undergo a surgical excision of mesh for pain or exposure at Magee-Women's Hospital were offered enrollment. Forty-two mesh-vagina tissue complexes were removed for the primary complaint of exposure (n=24) vs pain (n=18). Twenty-one patients agreed to have an additional vaginal biopsy away from the site of mesh that served as control tissue. T cells were examined via immunofluorescent labeling for cell surface markers CD4+ (T_h), CD8+ (cytotoxic) and foxp3 (T-regulatory cell). Frozen sections were stained with hematoxylin-eosin for gross morphologic condition and picrosirius red for collagen fiber analysis. Interrupted sodium-dodecyl sulfate gel electrophoresis was used to quantify the content of collagens type I and III, and the collagen III/I ratio. Transforming growth factor-β and connective tissue growth factor, which are implicated in the development of fibrosis, were measured via enzyme-linked immunosorbent assays. Data were analyzed with the Student's t tests, mixed effects linear regression, and Spearman's correlation coefficients.

RESULTS

Demographic data were not different between groups, except for body mass index, which was 31.7 kg/m² for the exposure group and 28.2 kg/m² for pain (P=.04). Tissue complexes demonstrated a marked, but highly localized, foreign body response. We consistently observed a teardrop-shaped fibroma that encapsulated mesh fibers in both pain and exposure groups, with the T cells localized within the tip of this configuration away from the mesh-tissue interface. All 3 T-cell populations were significantly increased relative to control: CD4⁺ T helper (P<.001), foxp3⁺ T regulatory (P<.001), and CD8⁺ cytotoxic T cell (P=.034) in the exposure group. In the pain group, only T-helper (P<.001) and T-regulatory cells (P<.001) were increased, with cytotoxic T cells (P=.520) not different from control. Picrosirius red staining showed a greater area of green (thin) fibers in the exposure group (P=.025) and red (thick) fibers in the pain group (P<.001). The ratio of area green/(yellow + orange + red) that represented thin vs thick fibers was significantly greater in the exposure group (P=.005). Analysis of collagen showed that collagen type I was increased by 35% in samples with mesh complications (exposure and pain) when compared with control samples (P=.043). Strong correlations between the profibrosis cytokine transforming growth factor-β and collagen type I and III were found in patients with pain (r≥0.833; P=.01) but not exposure (P>.7).

CONCLUSION

T cells appear to play a critical role in the long-term host response to mesh and may be a central pathway that leads to complications. The complexity of this response warrants further investigation and has the potential to broaden our understanding of mesh biology and clinical outcomes.

Vaginal Product Formulation Alters the Innate Antiviral Activity and Glycome of Cervicovaginal Fluids with Implications for Viral Susceptibility

Glycosylated proteins (i.e., mucins, IgG) are important mediators of innate antiviral immunity in the vagina; however, our current knowledge of the role that glycan themselves play in genital immunity is relatively low. Herein, we evaluate the relationship between innate antiviral immunity and glycomic composition in cervicovaginal lavage fluid (CVL) collected as part of a Phase I clinical trial testing the impact of two distinct formulations of the antiretroviral drug dapivirine. Using lectin microarray technology, we discovered that formulation (hydrogel- versus film-based delivery) impacted the CVL glycome, with hydrogel formulations inducing more changes, including a loss of high-mannose. The loss of this epitope correlated to a loss of anti-HIV-1 activity. Glycoproteomic identification of high-mannose proteins revealed a cohort of antiproteases shown to be important in HIV-1 resistance, whose expression covaried with the high-mannose signature. Our data strongly suggests high-mannose as a marker for secreted proteins mediating innate antiviral immunity in vaginal fluids and that drug formulation may impact this activity as reflected in the glycome.

Pregnancy and parturition negatively impact vaginal angle and alter expression of vaginal MMP-9

BACKGROUND

Parity is the greatest risk factor for the development of pelvic organ prolapse. The normally supported vagina is pulled up and back over the levator ani. Loss of vaginal angulation has been associated with prolapse and may represent injury to the vaginal supportive tissues.

OBJECTIVE

We proposed and examined the following hypotheses: (1) pregnancy and delivery impact vaginal support, leading to loss of vaginal angle; (2) vaginal angulation is restored postpartum; and (3) uncomplicated vaginal delivery (VD) is associated with accelerated remodeling of the vaginal fibrillar matrix.

MATERIALS AND METHODS

We prospectively enrolled a cohort of nulliparas in the first trimester of pregnancy, and abstracted demographic and delivery data. Metalloproteinase 9 (MMP-9) activity in the vagina was determined in the first and third trimesters and 1 year postpartum using a substrate activity assay. Uncomplicated VD was defined as none of the following: cesarean delivery, forceps or vacuum use, shoulder dystocia, obstetric anal sphincter laceration, or prolonged second-stage labor. Women were grouped dichotomously for comparison based on this definition. A subset of participants underwent transperineal ultrasound.

RESULTS

We enrolled 173 women with mean age of 25 ± 6 years and a body mass index of 20 ± 7 kg/m². Of the women, 67% identified as white/Caucasian, 27% black/African American, or 6% Hispanic/Latina. The mean delivery age was 39 ± 3 weeks, with 59% of participants experiencing uncomplicated VD. The MMP-9 median activity (ng/mg protein) was 242.0 (IQR, 18.7, 896.8; n = 157) in the first trimester, 130.8 (IQR, 14.6, 883.8; n = 148) in the third trimester, and 463.5 (IQR, 92.2, 900.0; n = 94) postpartum. The MMP-9 activity increased between the third trimester and 1 year postpartum (P = .006), with no significant difference between MMP-9 values in the first and third trimesters (P = .674). The vaginal angle became less acute from the first to the third trimester, and this change persisted postpartum. The vaginal angulation over the levator plate became more acute between the third trimester and postpartum in women who experienced uncomplicated VD compared to those who did not (-6.4 ± 22.1 degrees vs 17.5 ± 14.8 degrees; P = .017). Higher MMP-9 activity postpartum was associated with uncomplicated VD, with 67% of women in the third tertile achieving uncomplicated VD versus 39% in the first tertile (P = .029).

CONCLUSION

Loss of vaginal angulation occurs between trimesters, and women do not recover their baseline resting angle postpartum. MMP-9 activity increases postpartum. Women experiencing uncomplicated VD demonstrate higher postpartum MMP-9 activity and are more likely to have recovered their vaginal angle.

Obesity and older age as protective factors for vaginal cuff dehiscence following total hysterectomy

Studies have shown an increased risk of vaginal cuff dehiscence following total laparoscopic hysterectomy (TLH). Patient variables associated with dehiscence have not been well described. This study aims to identify factors associated with dehiscence following varying routes of total hysterectomy. This is a retrospective, matched, case-control study of women who underwent a total hysterectomy at a large, urban, university-based teaching hospital from January 2000 to December 2011. Women who underwent a total hysterectomy and had a dehiscence (n = 31) were matched by surgical mode to the next five total hysterectomies (n = 155). Summary statistics and conditional logistic regression were performed to compare cases to controls. Obese women (BMI ≥ 30) were 70 % less likely than normal weight women (BMI < 25) to experience a dehiscence (p = 0.02). When stratified by hysterectomy route, obese women were 86 % less likely to have a dehiscence following robotic-assisted total hysterectomy (RAH) and TLH than normal weight women (p = 0.04). Further, increasing age was protective of dehiscence in this subgroup of women (p = 0.02). Older age and obesity were associated with a decreased risk of dehiscence following RAH and TLH but not following other routes. Increased risk of dehiscence following TLH observed in previous studies may be partially due to patient characteristics.

Changes in genital tract immune cell populations after initiation of intrauterine contraception

OBJECTIVE

The primary target cells for the human immunodeficiency virus (HIV) infection in the genital tract are CD4 T cells that express CCR5 on the surface. Alterations in genital tract T cells that express CCR5 could impact HIV acquisition risk. We hypothesized that, when compared with baseline, the use of a hormonal intrauterine device (IUD) would alter HIV target cells (primarily CCR5+ CD4 cells) in the female genital tract more than a nonhormonal IUD.

STUDY DESIGN

Thirty-four healthy HIV-negative women aged 18-40 years who were seeking an IUD for contraception were assigned randomly to receive a levonorgestrel IUD or a copper T380A IUD. A parallel group of 8 control women who did not need contraception was also enrolled. Genital tract mucosal immune cell populations that were collected by cervical cytobrush and endometrial biopsy before and 2 months after IUD placement were analyzed by flow cytometry. Mean differences in cell number and percent that expressed receptors from baseline to follow-up examination were evaluated with the use of paired Student t tests.

RESULTS

Neither IUD altered the number of T cells within the upper and lower genital tracts. Levonorgestrel IUD users had a decrease in T cells that expressed the HIV coreceptor CCR5 in the endometrium and cervix after 2 months of use compared with baseline. There was a decrease in activated endometrial T cells in levonorgestrel IUD users and a decrease in activated cervical T cells in copper IUD users after 2 months of IUD use, compared with baseline.

CONCLUSION

Women who use IUDs have reduced expression of the CCR5 HIV coreceptor on T cells in the endometrium and cervix compared with expression before IUD placement. These findings suggest that susceptibility to HIV infection would not be increased by IUD use.

Mesh exposure and associated risk factors in women undergoing transvaginal prolapse repair with mesh

Objective. To determine frequency, rate, and risk factors associated with mesh exposure in women undergoing transvaginal prolapse repair with polypropylene mesh. Methods. Retrospective chart review was performed for all women who underwent Prolift Pelvic Floor Repair System (Gynecare, Somerville, NJ) between September 2005 and September 2008. Multivariable logistic regression was performed to identify risk factors for mesh exposure. Results. 201 women underwent Prolift. Mesh exposure occurred in 12% (24/201). Median time to mesh exposure was 62 days (range: 10-372). When mesh was placed in the anterior compartment, the frequency of mesh exposure was higher than that when mesh was placed in the posterior compartment (8.7% versus 2.9%, P = 0.04). Independent risk factors for mesh exposure were diabetes (AOR = 7.7, 95% CI 1.6-37.6; P = 0.01) and surgeon (AOR = 7.3, 95% CI 1.9-28.6; P = 0.004). Conclusion. Women with diabetes have a 7-fold increased risk for mesh exposure after transvaginal prolapse repair using Prolift. The variable rate of mesh exposure amongst surgeons may be related to technique. The anterior vaginal wall may be at higher risk of mesh exposure as compared to the posterior vaginal wall.

Bone resorption and fracture across the menopausal transition: the Study of Women's Health Across the Nation

OBJECTIVE

Bone turnover markers (BTMs) predict fracture in older women, whereas data on younger women are lacking. To test the hypothesis that BTMs measured before and after menopause predict fracture risk, we performed a cohort study of 2,305 women.

METHODS

Women attended up to nine clinic visits for an average of 7.6 ± 1.6 years; all were aged 42 to 52 years and were premenopausal or early perimenopausal at baseline. Incident fractures were self-reported. Serum osteocalcin and urinary cross-linked N-telopeptide of type I collagen (NTX) were measured at baseline. NTX was measured at each annual follow-up. Interval-censored survival models or generalized estimating equations were used to test whether baseline BTMs and changes in NTX, respectively, were associated with fracture risk. Hazard ratios (HRs) or odds ratios were calculated with 95% CIs.

RESULTS

Women who experienced fractures (n = 184) had about a 10% higher baseline median NTX (34.4 vs 31.5 nanomoles of bone collagen equivalents per liter per nanomole of creatinine per liter; P = 0.001), but there was no difference in osteocalcin. A 1-SD decrease in lumbar spine bone mineral density (BMD) measured premenopausally was associated with a higher fracture risk during menopause (HR, 1.50; 95% CI, 1.28-1.68). Women with a baseline NTX greater than the median had a 45% higher risk of fracture, multivariable-adjusted (HR, 1.46; 95% CI, 1.05-2.26). The HR of fracture among women with both the lowest spine BMD (quartile 1) and the highest NTX (quartile 4) at baseline was 2.87 (95% CI, 1.61-6.01), compared with women with lower NTX and higher BMD. Women whose NTX increased more than the median had a higher risk of fracture (odds ratio, 1.51; 95% CI, 1.08-2.10). Women who had baseline NTX greater than the median experienced greater loss of spine and hip BMD.

CONCLUSIONS

A higher urinary NTX excretion measured before menopause and across menopause is associated with a higher risk of fracture. Our results are consistent with the pathophysiology of transmenopausal changes in bone strength.

Collagen scaffold: a treatment for simulated maternal birth injury in the rat model

OBJECTIVE

We sought to determine the impact of a collagen scaffold on the healing response after simulated birth injury in a rodent model.

STUDY DESIGN

A total of 52 virgin animals were divided into the following groups: control (n = 18), injured untreated (n = 18), and injured treated with porcine small intestinal submucosa (SIS) (n = 16). Histopathology, immunofluorescence of collagens, and vaginal mechanical properties were used to assess the impact of injury and the subsequent healing response.

RESULTS

Collagen I/V decreased by 44% after birth injury relative to the controls (P = .001). Birth injury resulted in inferior mechanical properties of the vagina with a decrease of 38% in the tangent modulus and 44% in the tensile strength. SIS improved the collagen I/V and I/III ratios by 28% and 46%, respectively, paralleling the trend in the mechanical properties.

CONCLUSION

Simulated birth injury negatively affected vaginal biochemical and biomechanical properties long term. SIS treatment mitigated the impact of birth injury by enhancing tissue quality.

Symptomatic urinary tract infections after surgery for prolapse and/or incontinence

INTRODUCTION AND HYPOTHESIS

The purpose of our study was to estimate the frequency and risk factors for symptomatic urinary tract infection (UTI) after surgery for stress urinary incontinence (SUI) and/or pelvic organ prolapse (POP).

METHODS

Case-control study of 389 consecutive women who underwent surgery for POP and/or SUI. Cases were defined as a symptomatic, culture-confirmed UTI within 6 weeks of surgery. Multivariable logistic regression was used to determine independent risk factors.

RESULTS

Thirty five (9%) women developed a UTI. The risk of UTI was significantly increased by previous history of multiple UTIs (adjusted OR: 3.7, CI 1.4-10.1), increased distance between the urethra and the anus (adjusted OR: 1.4, CI 1.1-1.9), and prolonged duration of catheterization (adjusted odds ratio (OR) for >or=10 days: 4.2, 95% CI 1.5-11.6); 94.6% of catheterizing women were prescribed daily nitrofurantoin.

CONCLUSIONS

UTI is an important postoperative morbidity after urogynecologic surgery and is common in catheterizing women despite antibiotic prophylaxis.

Tensile properties of commonly used prolapse meshes

INTRODUCTION AND HYPOTHESIS

To improve our understanding of the differences in commonly used synthetic prolapse meshes, we compared four newer generation meshes to Gynecare PS using a tensile testing protocol. We hypothesize that the newer meshes have inferior biomechanical properties.

METHODS

Meshes were loaded to failure (n = 5 per group) generating load-elongation curves from which the stiffness, the load at failure, and the relative elongation were determined. Additional mesh samples (n = 3) underwent a cyclic loading protocol to measure permanent elongation in response to subfailure loading.

RESULTS

With the exception of Popmesh, which displayed uniform stiffness, other meshes were characterized by a bilinear behavior. Newer meshes were 70-90% less stiff than Gynecare (p < 0.05) and more readily deformed in response to uniaxial and cyclical loading (p < 0.001).

CONCLUSION

Relative to Gynecare, the newer generation of prolapse meshes were significantly less stiff, with irreversible deformation at significantly lower loads.

LOXL1 deficiency negatively impacts the biomechanical properties of the mouse vagina and supportive tissues

Mice deficient in lysyl oxidase-like1 protein (LOXL1(-/-)) develop pelvic organ prolapse (POP). We sought to determine the impact of LOXL1(-/-) on the biomechanical properties of the vagina and its supportive tissues tested as a complex. Tissues of nulliparous LOXL1(-/-) and age-matched wild type (WT) mice were tested to failure to obtain load-distension curves. Data were compared utilizing one-way analysis of variance and appropriate post hoc tests. The groups demonstrated different biomechanical behavior, with LOXL1(-/-) animals displaying a 31% decrease in ultimate load at failure (p=0.001). Experimental disruption of specific levels of support in WT mice failed to generate load-distension curves similar to the LOXL1(-/-) mice indicating a global instead of a site-specific tissue defect. The decrease in the ultimate load at failure in the LOXL1(-/-) mice suggests mechanically weaker tissues. LOXL1 mutation results in a global defect in connective tissues and correlates with altered biomechanical behavior of the vagina and supportive tissues.

Tensile properties of five commonly used mid-urethral slings relative to the TVT

We characterized the tensile properties of five mid-urethral slings relative to the Gynecare TVT. Slings were divided and loaded to failure. The heat-sealed Boston Scientific mid-section and the American Medical Systems (AMS) tensioning suture were examined separately. Analysis of the resulting nonlinear load elongation curves included calculation of low and high stiffness, the transition point between them (inflection point), load at failure, and relative elongation. Permanent elongation was measured after repetitive loads. Mean values were compared using a one-way analysis of variance. The curves of the Gynecare, Boston Scientific (no midsection) and AMS (no suture) were nonlinear with similar low stiffness and inflection points. The Bard, Caldera, and Mentor slings were stiffer. Heat sealing the Boston Scientific mid-section increased stiffness, while the AMS suture had negligible effect. Cyclical loading induced permanent elongation that was similar for Gynecare, AMS, and Boston Scientific (without mid-section) and lower for Bard, Caldera, and Mentor. With the exception of AMS, the overall effect of newer sling modifications was an increase in tensile stiffness.

Clinical utility of urine pregnancy assays to determine medical abortion outcome is limited

BACKGROUND

Determining medical abortion outcome commonly includes a costly evaluation such as ultrasonography or serial serum hCG testing. Urine pregnancy testing may represent a less costly alternative.

METHODS

This prospective diagnostic test evaluation study was part of a multisite randomized trial of 1080 women undergoing medical abortion up to 63 days' gestation who returned 1 and 2 weeks after receiving mifepristone. Low-sensitivity (LS) and high-sensitivity (HS) urine pregnancy tests were performed at each visit, and the results were compared to ultrasonography. Sensitivity, specificity, predictive values and likelihood ratios of each urine test were determined.

RESULTS

In the first week following abortion, 14.8% of the LS tests and 7.9% of the HS tests correctly predicted outcome. None of the LS tests and only 0.2% of the HS tests were falsely negative; however, 85.2% of the LS tests and 91.8% of the HS tests were falsely positive. In the second week following abortion, 39.1% of the LS tests and 33.8% of the HS tests correctly predicted the medical abortion outcome. Only 0.2% of the LS tests and 0.3% of the HS were falsely negative; however, 60.8% of the LS tests and 65.8% of the HS tests were falsely positive.

CONCLUSIONS

Both LS and HS urine pregnancy assays reliably assess clinical outcomes of medical abortions in cases of negative test results. However, the clinical utility of urine assay testing is limited because of the high rate of false-positive results.

Risk factors for cervicitis among women with bacterial vaginosis

BACKGROUND

Cervicitis commonly occurs in women with bacterial vaginosis (BV), often without concomitant chlamydial or gonococcal infection. The risk factors for cervicitis have not been described.

METHODS

We characterized the risk factors for cervicitis, which is defined as endocervical mucopurulent discharge or easily induced bleeding, among women with BV who were 14-45 years of age. Associations between cervicitis and the characteristics of the subjects, including the presence of specific vaginal bacteria and chlamydial or gonococcal infection detected by strand displacement assay, were analyzed.

RESULTS

Of 424 women with BV, 63 (15%) had cervicitis. Of these 63 women, only 8 (13%) had chlamydia or gonorrhea. The risk factors for cervicitis, adjusted for variables, included older age (P<.001, for trend), <or=12 years of education (odds ratio [OR], 2.4 [95% confidence interval {CI}, 1.3-4.6]; P=.006), new male sex partner (OR, 2.7 [95% CI, 1.4-5.4]; P=.004), female sex partner (OR, 6.2 [95% CI, 1.3-28.3]; P=.02), recent oral sex (OR, 2.3 [95% CI, 1.2-4.2]; P=.008), and absence of vaginal H2O2-producing Lactobacillus species (OR, 2.7; 95% CI, 3.3-5.9; P=.01). No association with cervicitis was seen for current douching or smoking, race, time since or frequency of intercourse, or presence or quantity of vaginal bacteria other than H2O2-producing Lactobacillus species.

CONCLUSIONS

Cervicitis is common among women with BV and is associated with some risk factors that are distinct from those associated with endocervical infection with Neisseria gonorrhoeae or Chlamydia trachomatis. Absence of H2O2-producing lactobacilli may contribute to the development of cervicitis.

Surgical procedures for urethral diverticula in women in the United States, 1979?1997

The objective of this study was to describe national rates of surgery for urethral diverticula in women. Data from the National Hospital Discharge Survey (NHDS), a federal database that samples inpatient hospitals in the United States, were analyzed from 1979 to 1997 for diagnosis and procedure codes using the ICD-9-CM classification system. The difference between the median age-adjusted rates from 1979 to 1988 and 1989 to 1997 were evaluated using the Mann-Whitney U test since the yearly rates fluctuated in a nonlinear fashion. Data from the National Statistics for Ambulatory Surgery (NSAS) database were analyzed from 1994 to 1996 in a similar fashion. The average age of women undergoing surgery for urethral diverticula increased from 41.6+/-15.1 years from 1979 to 1988 to 49.4+/-14.8 years from 1989 to 1997 (p=0.02). The average length of hospital stay decreased from 8.4+/-5.0 days in 1979 to 3.2+/-1.7 days in 1997 (p=0.007). Approximately 27,000 inpatient procedures were performed for the repair of urethral diverticula in the United States over a 19-year period, ranging from an estimated 500 to 3400 cases per year. The median age-adjusted rate of procedures decreased from 14.2 per 1 million women from 1979 to 1988 to 6.4 per 1 million women from 1989 to 1997 (p=0.009). Data from the NSAS indicated that an average of 6.7 surgeries per 1 million women per year were performed in the outpatient setting from 1994 to 1996. Age-adjusted rates of inpatient surgery for urethral diverticula were threefold higher for black compared to white women. Inpatient surgical repair of urethral diverticula is three times as high in black as compared to white women. These procedures are infrequent and rates appear to have decreased over time.

Safety and Efficacy Evaluations for Vaginal and Rectal Use of BufferGel in the Macaque Model

BACKGROUND

The nonhuman primate model allows for safety and efficacy testing of topical microbicide products.

GOAL

The goal of this study was to evaluate the safety and efficacy of vaginal and rectal applications of BufferGel (ReProtect, Inc.).

STUDY DESIGN

The safety of repeated product applications was evaluated by microflora, pH, vaginal colposcopy, and rectal lavage. To test efficacy in preventing chlamydia, infection was documented by culture and nucleic acid amplification tests.

RESULTS

Repeated vaginal or rectal applications of BufferGel were not associated with significant changes in microflora. BufferGel use had a transient acidifying effect on vaginal and rectal pH. Colposcopic observations remained relatively normal in all test animals. A slightly increased incidence of epithelial desquamation was noted after rectal product use compared with the control group. BufferGel did not prevent cervical or rectal chlamydial infection.

CONCLUSION

BufferGel has an acceptable safety profile after repeated vaginal and rectal use, but does not prevent chlamydial infection in the macaque models.

Contemporary management of preterm premature rupture of membranes: determinants of latency and neonatal outcome

Preterm premature rupture of membranes (PPROM) is responsible for 30% of neonatal morbidity and mortality in premature gestations. We sought to evaluate pregnancy outcomes in PPROM managed uniformly with antibiotics and steroids, and to determine what maternal factors influence latency. This was a retrospective analysis of 134 patients at 24 to 31.9 weeks with PPROM. Associations of maternal and pregnancy characteristics with latency were evaluated by chi-square for linear trend, nonparametric tests, or multivariable linear regression, as appropriate. Forty-three of 134 women (32%) had latencies greater than a week. Gestational age ( p < 0.001), admission white blood cell count ( p = 0.001), and amniotic fluid index ( p = 0.02) were independently predictive of latency. Histopathologic funisitis increased with pregnancy length. There were no fetal deaths or significant intraventricular hemorrhage past 28 weeks.

Ambulatory procedures for urinary incontinence in the United States, 1994-1996

OBJECTIVE

The objective of our study was to describe the national rates of ambulatory surgery for urinary incontinence in women.

STUDY DESIGN

We used the National Survey of Ambulatory Surgery, a federal database that samples outpatient surgery in the United States. Data from 1994 to 1996 were analyzed for diagnoses and procedures coded using the International Classification of Diseases, 9th revision, Clinical Modification, classification system. Age-adjusted rates were calculated with use of the 1990 census population and compared for change over time by using the score test for linear trend.

RESULTS

The estimated number of women undergoing outpatient surgery for urinary incontinence increased from 7,200 in 1994 to 15,900 in 1996 (P=.3), whereas the age-adjusted rate remained stable at approximately 10 procedures per 100,000 women per year. The procedures performed included "other repair of the bladder" (ICD-9-CM code 57.89), "other repair of urinary stress incontinence" (code 59.7), plication of the urethrovesical junction, suprapubic sling operation, retropubic urethral suspension, paraurethral suspension, and levator muscle operation. The mean age of women undergoing these procedures was 58+/-14.5 years. Women undergoing incontinence procedures were 76% white, 0.3% African American, and 24% other (including unknown). Ninety-two percent of the procedures were completed at hospitals, whereas 8% were performed at free-standing ambulatory surgery centers.

CONCLUSION

Between 1994 and 1996, the number of ambulatory surgeries for urinary incontinence in women doubled.

Clinical and cervical cytokine response to treatment with oral or vaginal metronidazole for bacterial vaginosis during pregnancy: a randomized trial

OBJECTIVE

To compare the efficacy of oral versus vaginal metronidazole treatment in pregnant women with bacterial vaginosis, and to compare cytokine profiles (interleukin-1beta, -6, and -8) in the cervical secretions of these women before and after treatment.

METHODS

Pregnant women with bacterial vaginosis diagnosed both by Gram stain and clinical criteria were randomized to receive oral (n=52) or vaginal (n=50) metronidazole therapy. Cervical specimens for cytokine analysis and vaginal fluid for evaluation of bacterial vaginosis were obtained at baseline and 4 weeks after treatment.

RESULTS

There was no significant difference in therapeutic cure rates (defined as a Gram stain score of 0-3 and the absence of all four clinical signs of bacterial vaginosis) between the two groups (71% and 70% for the oral and vaginal groups, respectively, P=1.0). Cervical levels of interleukin-1beta, -6, and -8 were significantly lower after treatment among the 72 women cured of bacterial vaginosis (P<.001, P=.001, and P=.02, respectively) but not among women who failed to respond to therapy. For interleukin-1beta and -6, a significant decrease in cytokine level was observed in both the oral and vaginal treatment groups.

CONCLUSION

One week of oral metronidazole and 5 days of intravaginal metronidazole are equally efficacious for treatment of bacterial vaginosis during pregnancy. The decrease in cervical interleukin-1beta, -6, and -8 levels among women who established a normal flora after treatment but not among those with persistent bacterial vaginosis suggests a direct linkage between vaginal flora abnormalities and elevated cervical levels of interleukin-1beta, -6, and -8.

Procedures for urinary incontinence in the United States, 1979-1997

OBJECTIVE

The objective of our study was to describe the national rates of surgery for urinary incontinence in women.

STUDY DESIGN

We used the National Hospital Discharge Survey, a federal database that samples inpatient hospitals in the United States. Data from 1979 to 1997 were analyzed for diagnoses and procedures coded by using the International Classification of Diseases, 9th revision, Clinical Modification, classification system. Age-adjusted rates were calculated by using the 1990 census population and compared for change over time with the score test for linear trend.

RESULTS

The number of women undergoing inpatient surgery for urinary incontinence has varied from 33000 in 1979 to 85000 in 1993. The rate of surgeries for incontinence has almost doubled, from 0.32 procedures per 1000 women per year in 1979 to 0.60 procedures per 1000 women per year in 1997 (P =.02). The number of suprapubic slings performed increased over time. Approximately 2100 slings were performed per year until 1996, when 7348 were performed, followed by 10,192 in 1997 (rate increase from 12 to 75.2 per 1000000 women per year, P =.03). Women undergoing incontinence procedures were 79% white, 3% African American, and the remaining 18% other (including unknown). Thirty-seven percent of cases were performed in the South, 25% in the Midwest and West, and 12% in the Northeast. From 1979 to 1997, the mean age of women at the time of surgery increased from 50.5 +/- 12.1 years to 56.6 +/- 13.3 years; mean length of hospital stay decreased from 9.9 +/- 4.5 days to 2.7 +/- 1.4 days (P <.001).

CONCLUSION

The rate of surgery for urinary incontinence in women has nearly doubled from 1979 to 1997.

Mifepristone and misoprostol and methotrexate/misoprostol in clinical practice for abortion

OBJECTIVE

The purpose of this study was to evaluate the efficacy, side-effect profile, and follow-up rates in women who obtain a medical abortion in a nonresearch setting.

STUDY DESIGN

From December 1, 2000, to June 30, 2001, we prospectively followed 218 women who had been evaluated in our private office for medical abortion. Women received either mifepristone 200 mg orally followed 1 to 2 days later by self-administered misoprostol 800 microg vaginally or methotrexate 50 mg/m(2) intramuscularly followed 3 to 7 days later by self-administered misoprostol 800 microg vaginally.

RESULTS

Of the 174 women who had a medical abortion, 148 women (85%) chose mifepristone/misoprostol, and 26 women (15%) chose methotrexate/misoprostol. In women up to 49 days of gestation, complete abortion occurred by the first follow-up visit in 82 of 86 women (95%; 95% CI, 89-99) and in 21 of 25 women (84%; 95% CI, 64-95) women, respectively. In women who used mifepristone/misoprostol from 50 to 63 days of gestation, complete abortions occurred in 56 of 59 women (95%; 95% CI, 86-99) women. Four women (2%; 95% CI, 1-6) were lost to follow-up.

CONCLUSION

Medical abortion with mifepristone/misoprostol and with methotrexate/misoprostol can be provided in a nonresearch setting with efficacy similar to that reported in the medical literature for research protocols.

Procedures for pelvic organ prolapse in the United States, 1979-1997

OBJECTIVE

The objective of our study was to describe national rates of surgery for pelvic organ prolapse.

STUDY DESIGN

We used the National Hospital Discharge Survey, a federal database that samples inpatient hospitals in the United States. Data from 1979 to 1997 were analyzed for diagnoses and procedures coded with the ICD-9-CM classification system. Age-adjusted rates were calculated by using the 1990 census population and compared for change over time by using the Score test for linear trend.

RESULTS

Approximately 200,000 women undergo inpatient procedures for prolapse in the United States each year, ranging from 165,000 in 1988 to 226,000 in 1979. There was a significant decrease in the overall age-adjusted rate of procedures performed over the study period, from 2.2 to 1.5 procedures per 1000 women (P =.01). The rate of prolapse procedures for women younger than 50 years decreased by more than half (1.9 to 0.8 per 1000 women, P <.001), whereas the rate remained stable in women who were aged 50 years and older (2.7 to 3.3 per 1000 women, P =.5).

CONCLUSION

Prolapse procedures are performed very frequently in the United States, although the rate has decreased slightly over time.

Episiotomy use in the United States, 1979-1997

OBJECTIVE

To describe episiotomy usage at vaginal delivery in the United States from 1979-1997.

METHODS

We used the National Hospital Discharge Survey, a federal database of a national sample of inpatient hospitals. Data from 1979 to 1997 were analyzed using International Classification of Diseases, Ninth Revision, Clinical Modification codes for diagnoses and procedures. Rates per 1000 women were calculated using the 1990 census population for women aged 15-44 years. We calculated the number of episiotomies per 100 vaginal deliveries. Rates and percentages were compared using the score test for linear trend.

RESULTS

The number of episiotomies ranged from a high of 2,015,000 in 1981 to a low of 1,128,000 in 1997. The age-adjusted annual rate for episiotomy with vaginal deliveries varied from 32.7 in 1979 to 18.7 in 1997 per 1000 women aged 15-44 years. The percentage of episiotomy with vaginal deliveries ranged from 65.3% in 1979 to 38.6% in 1997 (P <.001). Episiotomy with operative deliveries decreased over time (87.0% to 70.8%, P <.001), as did episiotomy with spontaneous deliveries (60.1% to 32.8%, P <.001). Women undergoing episiotomy were slightly younger (mean +/- standard deviation, 25.7 +/- 5.5 years) than women without episiotomy (26.2 +/- 5.7 years, P <.001). Black women (39%) were less likely to receive episiotomy than white women (60%, P <.001). More women with private insurance (62%) had episiotomy performed than women with government insurance (43%, P <.001).

CONCLUSION

Although episiotomy use has decreased over time, the most recent rate of 39 per 100 vaginal deliveries remains higher than evidence-based recommendations for optimal patient care.

Accuracy of serum beta-human chorionic gonadotropin cutoff values at 42 and 49 days' gestation

OBJECTIVE

The accuracy of serum beta-human chorionic gonadotropin levels as cutoff values for estimating gestational age was studied.

MATERIAL AND METHODS

A database was created using information from previously performed research studies, which allowed entry of women both less than and greater than 49 days' gestation, involving medical abortion. Serum beta-human chorionic gonadotropin determinations and vaginal ultrasonography were performed in all studies before treatment. A total of 574 women had data available for analysis. A receiver operating characteristic curve was created to evaluate the predictive value of potential beta-human chorionic gonadotropin cutoff values for 42 and 49 days' gestation.

RESULTS

Appropriate serum beta-human chorionic gonadotropin cutoff values for 42 and 49 days' gestation were 23,745 mIU/mL (sensitivity, 96%; specificity, 91%; positive predictive value, 68%; negative predictive value, 99%) and 71,160 mIU/mL (sensitivity, 95%; specificity, 62%; positive predictive value, 76%; negative predictive value, 91%), respectively. Under 42 days' gestation, the serum beta-human chorionic gonadotropin-time relationship appears to be linear, with a greater diversity of individual values after 42 days.

CONCLUSION

Serum beta-human chorionic gonadotropin values can be used with reasonable accuracy to screen for a gestational age up to 49 days' gestation.

Neuron-specific expression of therapeutic proteins: evaluation of different cellular promoters in recombinant adenoviral vectors

In order to achieve neuron-restricted expression of antiapoptotic proteins, cellular promoters were investigated for their expression profiles in the context of adenoviral vectors. Both the synapsin 1 gene and the tubulin alpha1 gene promoters were strictly neuron specific in cocultures of primary neurons with their essential feeder cells. The neuron-specific enolase gene promoter exhibited only weak activity in cultured hippocampal neurons and was not neuron specific in preparations of cerebellar granule cells. By attaining virtually 100% transduction efficiency we were able to generate "quasi-transgenic" primary neuron cultures using both differentiated and completely undifferentiated hippocampal neurons. In a functional assay, we used the synapsin promoter to evaluate the effect of Bcl-X(L) overexpression on potassium-withdrawal-induced apoptosis of cerebellar granule neurons. We found nearly complete inhibition of caspase-9 and -3 activation and apoptosis, indicating a major role for mitochondrial pathways in this paradigm of neuronal cell death. The excellent suitability of the synapsin promoter as a strong panneuronal promoter was further demonstrated by its restricted neuronal activity in various brain regions of adult rats in vivo.

Glycine 384 is required for presenilin-1 function and is conserved in bacterial polytopic aspartyl proteases

Endoproteolysis of beta-amyloid precursor protein (betaAPP) and Notch requires conserved aspartate residues in presenilins 1 and 2 (PS1 and PS2). Although PS1 and PS2 have therefore been proposed to be aspartyl proteases, no homology to other aspartyl proteases has been found. Here we identify homology between the presenilin active site and polytopic aspartyl proteases of bacterial origin, thus supporting the hypothesis that presenilins are novel aspartyl proteases.

Predicting cesarean delivery with decision tree models

OBJECTIVE

The purpose of this study was to determine whether decision tree-based methods can be used to predict cesarean delivery.

STUDY DESIGN

This was a historical cohort study of women delivered of live-born singleton neonates in 1995 through 1997 (22,157). The frequency of cesarean delivery was 17%; 78 variables were used for analysis. Decision tree rule-based methods and logistic regression models were each applied to the same 50% of the sample to develop the predictive training models and these models were tested on the remaining 50%.

RESULTS

Decision tree receiver operating characteristic curve areas were as follows: nulliparous, 0.82; parous, 0.93. Logistic receiver operating characteristic curve areas were as follows: nulliparous, 0.86; parous, 0.93. Decision tree methods and logistic regression methods used similar predictive variables; however, logistic methods required more variables and yielded less intelligible models. Among the 6 decision tree building methods tested, the strict minimum message length criterion yielded decision trees that were small yet accurate. Risk factor variables were identified in 676 nulliparous cesarean deliveries (69%) and 419 parous cesarean deliveries (47.6%).

CONCLUSION

Decision tree models can be used to predict cesarean delivery. Models built with strict minimum message length decision trees have the following attributes: Their performance is comparable to that of logistic regression; they are small enough to be intelligible to physicians; they reveal causal dependencies among variables not detected by logistic regression; they can handle missing values more easily than can logistic methods; they predict cesarean deliveries that lack a categorized risk factor variable.

Cellular expression and proteolytic processing of presenilin proteins is developmentally regulated during neuronal differentiation

We have determined the expression of the Alzheimer's disease-associated proteins presenilin-1 and presenilin-2 in primary cultures of rat hippocampal neurons. Neurons highly express presenilin-1 and presenilin-2, whereas both proteins were not detected in astrocytes. Further, we have analyzed the subcellular localization and expression in rat hippocampal neurons during development. Although presenilin proteins were localized predominantly to the endoplasmic reticulum in nonneuronal cells transfected with presenilin cDNAs, in neurons, presenilin proteins were also found in compartments not staining with antibodies to grp78(BiP). Presenilin-1 and presenilin-2 were predominantly detected in vesicular structures within the somatodendritic compartment with much less expression in axons. Polarized distribution of presenilin-1 and presenilin-2 differs slightly, with more presenilin-2 expressed in axons compared with presenilin-1. Presenilin expression was found to be developmentally regulated. Presenilin expression strongly increased during neuronal differentiation until full morphological polarization and then declined. No full-length presenilin-1 or presenilin-2 could be detected within cell lysates. At early developmental stages the expected approximately 34-kDa N-terminal proteolytic fragment of presenilin-1 and the approximately 38-kDa fragment of presenilin-2 were detected. Later during differentiation we predominantly detected a approximately 38-kDa fragment for presenilin-1 and a approximately 42-kDa fragment for presenilin-2. By epitope mapping, we show that these slower migrating peptides represent N-terminal proteolytic fragments, cleaved C-terminal to the conventional site of processing. It is noteworthy that both presenilin-1 and presenilin-2 undergo alternative proteolytic cleavage at the same stage of neuronal differentiation. Regulation of presenilin expression and proteolytic processing might have implications for the pathological as well as the biological function of presenilins during aging in the human brain.