Cohesive behavior of soft biological adhesives: experiments and modeling

Extracellular proteins play a key role in generating and maintaining cohesion and adhesion in biological tissues. These "natural glues" are involved in vital biological processes such as blood clotting, wound healing and maintaining the structural integrity of tissues. Macromolecular assemblies of proteins can be functionally stabilized in a variety of ways in situ that include ionic interactions as well as covalent crosslinking to form protein networks that can extend both within and between tissues. Within tissues, myriad cohesive forces are required to preserve tissue integrity and function, as are additional appropriate adhesive forces at interfaces both within and between tissues of differing composition. While the mechanics of some key structural adhesive proteins have been characterized in tensile experiments at both the macroscopic and single protein levels, the fracture toughness of thin proteinaceous interfaces has never been directly measured. Here, we describe a novel and simple approach to measure the cohesive behavior and toughness of thin layers of proteinaceous adhesives. The test is based on the standard double-cantilever beam test used for engineering adhesives, which was adapted to take into account the high compliance of the interface compared with the beams. This new "rigid double-cantilever beam" method enables stable crack propagation through an interfacial protein layer, and provides a direct way to measure its full traction-separation curve. The method does not require any assumption of the shape of the cohesive law, and the results provide abundant information contributing to understanding the structural, chemical and molecular mechanisms acting in biological adhesion. As an example, results are presented using this method for thin films of fibrin-a protein involved in blood clotting and used clinically as a tissue bio-adhesive after surgery-with the effects of calcium and crosslinking by Factor XIII being examined. Finally, a simple model is proposed, demonstrating how a bell-shaped cohesive law forms during the failure of the fibrin interface based on an eight-chain model whose structure degrades and changes configuration with stress.

The ADDOPT study (Acupuncture to Decrease Disparities in Outcomes of Pain Treatment): feasibility of offering acupuncture in the community health center setting

OBJECTIVES

This article describes the feasibility and acceptability of the Acupuncture to Decrease Disparities in Outcomes of Pain Treatment (ADDOPT) trial, which incorporates acupuncture as an adjunct to usual treatment for chronic pain in urban health centers.

DESIGN

The study assessed feasibility (ability to carry out in real-world practice; adequacy of resources; acceptability to patients, acupuncturists, and primary care clinicians).

SETTING

Four (4) community health centers in the Bronx, NY, participating in the New York City Research and Improvement Networking Group (NYC RING), a practice-based research network dedicated to decreasing health disparities through primary care research and quality improvement in the urban safety net setting, were involved.

SUBJECTS

The subjects comprised participants receiving care for chronic pain due to osteoarthritis, or neck or back pain at four Bronx health centers serving low-income families.

INTERVENTION

The intervention involved up to 14 weekly acupuncture treatments.

OUTCOME MEASURES

Pain and functional status are assessed during a 6-week run-in period before, during, and postacupuncture treatment using the Brief Pain Inventory and the 12-Item Short Form Health Survey. This article reports on baseline status, referral and recruitment, engagement with treatment, and delivery of the intervention across sites.

RESULTS

Of 400 patients referred, 185 have initiated treatment. The majority of attending physicians have referred, most commonly for back pain (n=103; 60.6%). Participants' average age is 53.9 (standard deviation [SD] 14.1); 54.1% are Hispanic; and 57.6% are on Medicaid. Half (48%) report "poor" or "fair" overall health. Patients report an average disability score of 74 (SD 27.0) and baseline pain severity on the Brief Pain Inventory of 6 (SD 1.9). Patients have completed a mean of 8.0 (SD 4.7) treatments; 72.4% complete >5 sessions.

CONCLUSIONS

Clinicians in this urban setting have incorporated acupuncture into chronic pain management. Despite disability and lack of familiarity, patients initiate acupuncture and show high levels of engagement with treatment.

Examining role change in primary care practice

PURPOSE

While experts suggest that primary care needs far-reaching transformation that includes adding or reconfiguring roles to improve patient care, little is known about how role change occurs in practice settings. Methods This was a cross-case comparative analysis of 3 projects designed to improve health behavior counseling in primary care practices by adding to or changing clinical support staff roles. Qualitative data (site visits notes, grantee reports, interviews with grantees, and online diary entries) were analyzed to examine instances of role change in depth, using role change theory as an organizing framework. Results Practice team members had greater success taking on new roles when patients valued the services provided. Often, it was easier to a hire a new person into a new role rather than have an existing practice member shift responsibilities. This was because new personnel had the structural autonomy, credibility, and organizational support needed to develop new responsibilities and routines.

CONCLUSION

As primary care delivery systems are redesigned in ways that rely on new roles to deliver care, understanding how to effectively add or change staff roles is essential and requires attention to patients', practice members', and institutions' support for new roles.

Testing adolescents for sexually transmitted infections in urban primary care practices: results from a baseline study

OBJECTIVE

Sexually active urban adolescents experience a high burden of sexually transmitted infections (STI). Adolescents often access medical care through general primary care providers; their time alone with a provider increases the likelihood that youth will disclose risky behavior, which may result in STI testing. Our goals were to assess the association (if any) between the provision of time alone and STI testing, and describe the rates of STI testing among sexually active adolescents in urban primary care.

METHODS

Youth (aged 12-19 years) presenting for care at 4 urban health centers were invited to complete post-visit surveys of their experience. Sexually transmitted infection screening rates were obtained from the clinical information systems (CIS); CIS data were linked to survey responses.

RESULTS

We received 101 surveys. Surveyed youth experienced time alone in 69% of all visits. Time alone varied by age (older teens experienced more time alone), and it occurred more frequently in preventive visits (71%) versus nonpreventive visits (33%). It did not vary by gender. Forty-two of the 46 sexually active youth experienced time alone. Screening rates for sexually active females, either at the index visit or within 6 months prior to the index visit, were 17.9% for human immunodeficiency virus and 32.1% for gonorrhea/Chlamydia. No sexually active surveyed males were tested. Overall screening rates varied widely across practices (human immunodeficiency virus 0%-29%; gonorrhea/Chlamydia 7%-29%). There was no difference in screening rates among youth with and without time alone.

CONCLUSION

STI testing for adolescents is being conducted in this primary care urban population, especially for sexually active females. However, clinicians in this setting are not screening females consistently enough and rarely screen males. We were unable to test our hypothesis that provision of time alone was associated with a higher rate of STI testing. Site differences suggest substantial variation in clinician practices that should be addressed in quality improvement interventions.

A collaborative approach to control hypertension in diabetes: outcomes of a pilot intervention

We sought to develop and pilot an intervention to improve blood pressure (BP) and other intermediate outcomes (hemoglobin A1c, low-density lipoprotein cholesterol) of diabetes in a low-income, ethnically diverse population. English- or Spanish-speaking primary care patients with BP ≥ 140/90 on 2 visits in the past 12 months and any level of A1c were randomized to usual care (n = 24) or intervention (n = 31). Home health nurses assessed self-management and medication adherence, and they performed health behavior counseling. Participants transmitted daily BP and glucose results using simple home telemetry units to the nurse coordinator; these results were then aggregated and transmitted weekly to primary care providers to facilitate intensified treatment. After controlling for baseline levels, a significantly larger proportion of the intervention group was at goal for BP (adjusted OR = 9.3, P = .006) and A1c (AOR = 4.3, P = .049), but not for low-density lipoprotein cholesterol (AOR = 1.1, P =.86). Clinicians made more BP medication changes in the intervention group compared to the control group (8.3 vs 3.8, approaching significance at P = .06). Self-reported medication adherence and self-care behaviors were not significantly improved. We successfully developed a telephone- and email-based collaboration between home health nurses and primary care clinicians to address poorly controlled hypertension in an ethnically diverse population. The intervention, combining enhanced feedback to patients and their primary care providers and individualized behavior change support by home health nurses, is effective for improving BP and glucose in this setting.

Enzyme replacement therapy prevents dental defects in a model of hypophosphatasia

Hypophosphatasia (HPP) occurs from loss-of-function mutation in the tissue-non-specific alkaline phosphatase (TNALP) gene, resulting in extracellular pyrophosphate accumulation that inhibits skeletal and dental mineralization. TNALP-null mice (Akp2(-/-)) phenocopy human infantile hypophosphatasia; they develop rickets at 1 week of age, and die before being weaned, having severe skeletal and dental hypomineralization and episodes of apnea and vitamin B(6)-responsive seizures. Delay and defects in dentin mineralization, together with a deficiency in acellular cementum, are characteristic. We report the prevention of these dental abnormalities in Akp2(-/-) mice receiving treatment from birth with daily injections of a mineral-targeting, human TNALP (sALP-FcD(10)). sALP-FcD(10) prevented hypomineralization of alveolar bone, dentin, and cementum as assessed by micro-computed tomography and histology. Osteopontin--a marker of acellular cementum--was immuno-localized along root surfaces, confirming that acellular cementum, typically missing or reduced in Akp2(-/-) mice, formed normally. Our findings provide insight concerning how acellular cementum is formed on tooth surfaces to effect periodontal ligament attachment to retain teeth in their osseous alveolar sockets. Furthermore, they provide evidence that this enzyme-replacement therapy, applied early in post-natal life--where the majority of tooth root development occurs, including acellular cementum formation--could prevent the accelerated tooth loss seen in individuals with HPP.

Challenges of providing confidential care to adolescents in urban primary care: clinician perspectives

PURPOSE

Clinician time alone with an adolescent has a major impact on disclosure of risk behavior. This study sought to describe primary care clinicians' patterns of delivering time alone, decision making about introducing time alone to adolescents and their parents, and experiences delivering confidential services.

METHODS

We undertook qualitative interviews with 18 primary care clinicians in urban health centers staffed by specialists in pediatrics, family medicine, and adolescent medicine.

RESULTS

The annual preventive care visit is the primary context for provision of time alone with adolescents; clinicians consider the parent-child dynamic and the nature of the chief complaint for including time alone during visits for other than preventive care. Time constraints are a major barrier to offering time alone more frequently. Clinicians perceive that parental discomfort with time alone is rare. Many clinicians wrestle with internal conflict about providing confidential services to adolescents with serious health threats and regard their role as facilitating adolescent-parent communication. Health systems factors can interfere with delivery of confidential services, such as inconsistent procedures for determining whether unaccompanied youth would be seen.

CONCLUSION

Despite competing time demands, clinicians report commitment to offering time alone during preventive care visits and infrequently offer it at other times. Experienced clinicians can gain skills in the art of managing complex relationships between adolescents and their parents. Office systems should be developed that enhance the consistency of delivery of confidential services.

Delivery of confidential care to adolescent males

PURPOSE

Primary care providers' (PCPs') provision of time alone with an adolescent without the parents present (henceforth referred to as "confidential care") has a significant impact on adolescents' disclosure of risk behavior. To inform the development of interventions to improve PCPs' delivery of confidential care, we obtained the perspectives of adolescent males and their mothers about the health care concerns of adolescent males and the provision of confidential care.

METHODS

This focus-group study (5 groups: 2 with adolescent males and 2 with mothers) used standard qualitative methods for analysis. We recruited mother/son dyads who had been seen at urban primary care practices.

RESULTS

Adolescents' health concerns focused on pregnancy and sexually transmitted infections; mothers took a broader view. Many adolescents felt that PCPs often delivered safe sex counseling in a superficial, impersonal manner that did not add much value to what they already knew, and that their PCP's principal role was limited to performing sexually transmitted infection testing. Though adolescents cited a number of advantages of confidential care and disclosure, they expressed some general mistrust in PCPs and concerns about limits of confidentiality. Rapport and relationship building with their PCP are key elements to adolescents' comfort and increased disclosure. Overall, mothers viewed confidential care positively, especially in the context of continuity of care, but many felt excluded.

CONCLUSIONS

To increase adolescents' perception of the relevance of primary care and to foster disclosure during health encounters, our participants described the critical nature of a strong doctor-patient relationship and positive physician demeanor and personalized messages, especially in the context of a continuity relationship. Regular, routine inclusion of confidential care time starting early in adolescence, as well as discussion of the purpose and limitations of confidentiality with parents and adolescents, could lead to greater parental comfort with confidential care and increased disclosure by the adolescent.

Primary care providers' reports of time alone and the provision of sexual health services to urban adolescent patients: results of a prospective card study

Confidential care is an essential element of quality adolescent primary care. Twenty-one primary care providers tracked provision of confidential care (time alone with adolescent) and sexual health services in clinics serving low-income, primarily minority communities. Over 144 visits attended by a parent, 68% involved time alone with the adolescent. Time alone was 18 times higher for physicals than same day or walk-in visits, and 3 times higher if teen presented a sex complaint. Provision of sexual health services was 3 times higher for those who had time alone with the provider, especially among girls. The results indicate some missed opportunities to deliver needed services to at-risk populations, especially among boys.

Implementation of a pilot primary care lifestyle change intervention for families of pre-school children: lessons learned

OBJECTIVE

We used Glasgow's RE-AIM framework to evaluate the feasibility of a primary care-based intervention to decrease behaviors that place urban children at risk for obesity.

METHODS

During preventive visits of 2-5-year olds between February 2006 and May 2007, parents completed a health behavior assessment. Primary care providers engaged parents in brief goal setting and referred them to a lifestyle counselor. Evaluation involved medical record review, interviews with staff and clinicians, and health behavior assessment via a pre- and post-intervention telephone survey.

RESULTS

Families reached by the intervention did not differ from families who were not. The intervention was adopted by 14 of 17 clinicians. The health assessment was implemented in 32% of preventive visits (N=354). Of those, goal setting by physicians occurred in 59%, with 55% referred to the lifestyle counselor. We were unable to demonstrate effectiveness to change adult or child nutrition or physical activity, as complete data were available for only 34 families.

CONCLUSION

Goal setting with referral for more intensive lifestyle counseling for obesity prevention in high risk families is feasible and acceptable in primary care.

PRACTICE IMPLICATIONS

Patient educators can be integrated into primary care to achieve preventive care goals.

Counseling to prevent obesity among preschool children: acceptability of a pilot urban primary care intervention

PURPOSE

To help design effective primary care-based interventions, we explored urban parents' reactions to a pilot and feasibility study designed to address risk behaviors for obesity among preschool children.

METHODS

We conducted 3 focus groups (2 in English, 1 in Spanish) to evaluate the pilot intervention. Focus group participants explored the acceptability of the pilot intervention components (completion of a new screening tool for risk assessment, discussion of risk behaviors and behavior change goal setting by physicians, and follow-up contacts with a lifestyle counselor) and the fidelity of the pilot intervention delivery.

RESULTS

Parents expressed a desire to change behaviors to achieve healthier families. They believed that doctors should increase their focus on healthy habits during visits. Parents were more accepting of nutrition discussions than increasing activity (citing a lack of safe outdoor space) or decreasing sedentary behaviors (citing many benefits of television viewing). Contacts with the lifestyle counselor were described as empowering, with parents noting her focus on strategies to achieve change for the whole family while recognizing that many food behaviors relate to cultural heritage. Parents expressed frustration with physicians for offering advice about changing behavior but not how to achieve it, for dismissing concerns about picky eating or undereating, and in some cases for labels of overweight that they believed were inappropriately applied.

CONCLUSIONS

Parents welcomed efforts to address family lifestyle change in pediatric visits. The model of physician goal setting with referral for behavior change counseling is highly acceptable to families. Future interventions should acknowledge parental concerns about undereating and perceived benefits of television viewing.

Vaginal hygiene practices and perceptions among women in the urban Northeast

To inform development of an intervention to decrease vaginal douching among Latinas, we conducted a survey of 335 women aged 16-45 years in primary care offices in the urban Northeast, including many Hispanic women (59.7%). About a third (30.7%) indicated that they had never douched. Of women who had ever douched (n = 235), 51.1% indicated they no longer douche. Women reported using a variety of products for douching and non-douching hygiene, including U.S.-made and imported commercial products as well as traditional products. Compared to Black women, more Hispanic women reported never douching and use of imported products. More positive beliefs about the benefits of douching and its safety were reported by women who currently douche. Health care providers should be aware that women may be using imported and traditional products, the safety of which is unknown. Advice about douching from health care providers may be effective for some women in helping them choose to stop or not initiate the practice.

In vitro osteogenesis assays: influence of the primary cell source on alkaline phosphatase activity and mineralization

In trabecular bone fracture repair in vivo, osteogenesis occurs through endochondral ossification under hypoxic conditions, or through woven bone deposition in the vicinity of blood vessels. In vitro osteogenesis assays are routinely used to test osteoblastic responses to drugs, hormones, and biomaterials for bone and cartilage repair applications. These cell culture models recapitulate events that occur in woven bone synthesis, and are carried out using primary osteoblasts, osteoblast precursors such as bone marrow-derived mesenchymal stromal cells (BMSCs), or various osteoblast cell lines. With time in culture, cell differentiation is typically assessed by examining levels of alkaline phosphatase activity (an early osteoblast marker) and by evaluating the assembly of a collagen (type I)-containing fibrillar extracellular matrix that mineralizes. In this review, we have made a comparative analysis of published osteogenic assays using calvarial cells, calvaria-derived cell lines, and bone marrow stromal cells. In all of these cell types, alkaline phosphatase activity shows similar progression over time using a variety of osteogenic and mineralizing media conditions; however, levels of alkaline phosphatase activity are not proportional to observed mineralization levels.

Matrix Gla protein inhibition of tooth mineralization

Extracellular matrix (ECM) mineralization is regulated by mineral ion availability, proteins, and other molecular determinants. To investigate protein regulation of mineralization in tooth dentin and cementum, and in alveolar bone, we expressed matrix Gla protein (MGP) ectopically in bones and teeth in mice, using an osteoblast/odontoblast-specific 2.3-kb Col1a1 promoter. Mandibles were analyzed by radiography, micro-computed tomography, light microscopy, histomorphometry, and transmission electron microscopy. While bone and tooth ECMs were established in the Col1a1-Mgp mice, extensive hypomineralization was observed, with values of unmineralized ECM from four- to eight-fold higher in dentin and alveolar bone when compared with that in wild-type tissues. Mineralization was virtually absent in tooth root dentin and cellular cementum, while crown dentin showed "breakthrough" areas of mineralization. Acellular cementum was lacking in Col1a1-Mgp teeth, and unmineralized osteodentin formed within the pulp. These results strengthen the view that bone and tooth mineralization is critically regulated by mineralization inhibitors.

Avian eggshell structure and osteopontin

The avian eggshell primarily consists of calcium carbonate mineral (calcite) and matrix proteins. Here we review matrix-mineral relationships in the eggshell at the ultrastructural level using scanning and transmission electron microscopy, and describe the distribution of osteopontin (OPN) as determined by colloidal gold immunolabeling for OPN. A rich protein network integrated within the calcitic structure of the eggshell shows variable, region-specific organization that included layered fibrous planar sheets of matrix, thin filamentous threads, thin film-like surface coatings, vesicular structures and isolated proteins residing on cleaved {104} crystallographic faces of the eggshell calcite. Except for the vesicular structures, these matrix structures all immunolabeled strongly for OPN. Given the potent mineralization- inhibiting function of OPN, we discuss how this protein might regulate eggshell growth rate and inhibit calcification at specific compartmental boundaries to provide eggshell form.

Vaginal douching among Latinas: practices and meaning

OBJECTIVES

Vaginal douching is widely practiced by American women, particularly among minority groups, and is associated with increased risk of pelvic and vaginal infections. This research sought to investigate vaginal hygiene practices and meaning associated with them among Latina women and adolescents. Study results would guide development of an intervention to decrease douching among Latinas.

METHODS

In depth qualitative interviews conducted with English- and Spanish-speaking women aged 16-40, seeking care for any reason who reported douching within the last year (n = 34). Interviews were audiotaped, transcribed and analyzed using qualitative methods. One-third of interviews were conducted in Spanish.

RESULTS

Two explanatory models for douching motives emerged: one stressed cosmetic benefits; the other, infection prevention and control. Most women reported douching to eliminate menstrual residue; a small number reported douching in context of sexual intercourse or vaginal symptoms. Many were unaware of associated health risks. Respondents typically learned about douching from female family members and friends. Male partners were described as having little to no involvement in the decision to douche. Women varied in their willingness to stop douching. Two-thirds reported receiving harm reduction messages about "overdouching". About half indicated previous discussion about douching with health care providers; some had reduced frequency in response to counseling. A number of previously unreported vaginal hygiene practices and products were described, including use of a range of traditional hygiene practices, and products imported from outside the US.

CONCLUSIONS

Respondents expressed a range of commitment to douching. Counseling messages acknowledging benefits women perceive as well as health risks should be developed and delivered tailored to individual beliefs. Further research is needed to assess prevalence and safety of previously unreported practices.

Using NAMCS to characterize the urban health care safety net

PURPOSE

Data from the National Ambulatory Medical Care Survey (NAMCS) have been used to describe many facets of ambulatory care, but have been underutilized in their application to the urban health care safety net. Our interest was in comparing the visit characteristics of inner city primary care practices in New York City with those of the rest of the country.

METHODS

Data were collected in 15 primary care centers affiliated with the New York City Research & Improvement Networking Group (NYC RING), a practice-based research network. Physicians completed the cross-sectional survey after patient visits using a slightly augmented version of the standard NAMCS form. Results were then compared with a subset of the Centers for Disease Control and Prevention's public-use dataset for the 2002 NAMCS, selecting only visits to primary care providers and practices in metropolitan statistical areas (N=8,598). Variables of primary interest were visit lengths and diagnoses, adjusting for age and sex.

RESULTS

Physicians in NYC RING collected data on 1,861 encounters. Compared with the national sample, our clinicians see 140% more diabetes visits, 70% more hypertension, and 90% more asthma, and provide 88% more dermatologic care and over 300% more reproductive health services. Visits were, on average, one minute longer in our inner city practices (p<.05), and were generally longer across all diagnosis categories than in the national sample.

CONCLUSIONS

The prevalence of metabolic syndrome and environmentally-related conditions and the provision of more than average specialty care characterize safety net care in New York City.

Chitosan-glycerol phosphate/blood implants elicit hyaline cartilage repair integrated with porous subchondral bone in microdrilled rabbit defects

OBJECTIVE

We have previously shown that microfractured ovine defects are repaired with more hyaline cartilage when the defect is treated with in situ-solidified implants of chitosan-glycerol phosphate (chitosan-GP) mixed with autologous whole blood. The objectives of this study were (1) to characterize chitosan-GP/blood clots in vitro, and (2) to develop a rabbit marrow stimulation model in order to determine the effects of the chitosan-GP/blood implant and of debridement on the formation of incipient cartilage repair tissue.

METHODS

Blood clots were characterized by histology and in vitro clot retraction tests. Bilateral 3.5 x 4 mm trochlear defects debrided into the calcified layer were pierced with four microdrill holes and filled with a chitosan-GP/blood implant or allowed to bleed freely as a control. At 1 day post-surgery, initial defects were characterized by histomorphometry (n=3). After 8 weeks of repair, osteochondral repair tissues between or through the drill holes were evaluated by histology, histomorphometry, collagen type II expression, and stereology (n=16).

RESULTS

Chitosan-GP solutions structurally stabilized the blood clots by inhibiting clot retraction. Treatment of drilled defects with chitosan-GP/blood clots led to the formation of a more integrated and hyaline repair tissue above a more porous and vascularized subchondral bone plate compared to drilling alone. Correlation analysis of repair tissue between the drill holes revealed that the absence of calcified cartilage and the presence of a porous subchondral bone plate were predictors of greater repair tissue integration with subchondral bone (P<0.005), and of a higher total O'Driscoll score (P<0.005 and P<0.01, respectively).

CONCLUSIONS

Chitosan-GP/blood implants applied in conjunction with drilling, compared to drilling alone, elicited a more hyaline and integrated repair tissue associated with a porous subchondral bone replete with blood vessels. Concomitant regeneration of a vascularized bone plate during cartilage repair could provide progenitors, anabolic factors and nutrients that aid in the formation of hyaline cartilage.

Perspectives on confidential care for adolescent girls

PURPOSE

We wanted to obtain perspectives of mothers and daughters on facilitators of and barriers to with adolescent girls' timely access to risk-appropriate reproductive care.

METHODS

We conducted 5 separate focus groups with Latina and black mothers and their adolescent daughters. All participants resided in impoverished neighborhoods of New York City. Participants addressed mothers' roles in helping girls initiate gynecologic care, perceived role of physicians in daughters' sexual health, including the provision of confidential care, and perceived need for girls' gynecologic care. Data were analyzed using qualitative data analysis methods.

RESULTS

Mothers see themselves as their daughters' primary protectors against daughters' poor reproductive outcomes. Many believe that confidential care promotes risky behavior and undermines mothers' efforts to protect girls. Mothers endorse facilitating gynecologic care and entering alliances with physicians but see the need for care as arising only after girls' sexual debut. Unfortunately, maternal awareness of sexual activity is low. Adolescent girls express considerable discomfort around reproductive health care and negotiating maternal involvement, and they fear breaches in confidentiality.

CONCLUSIONS

A lack of trust in health care clinicians and the mother's gatekeeper role are key barriers to girls' transition to reproductive care. Consistently including a confidential component to health care visits in early adolescence, with preparation for both mothers and daughters, may reduce the distrust and discomfort.

Predictors of timely initiation of gynecologic care among urban adolescent girls

PURPOSE

To determine whether or not critical sexual health services are delivered to low-income girls, and to identify predictors of timely initiation of gynecologic care for sexually active adolescent girls. Few studies have addressed the interval between sexual debut and risk-appropriate primary care services.

METHODS

We conducted an anonymous, cross-sectional, laptop-based, self-administered branching survey of 9th-12th grade girls in three Bronx public high schools (n = 819).

RESULTS

Over half (60.0%) had an opportunity for confidential care at last clinical visit. Only 27% of sexually active girls had informed any clinician that they had been sexually active; 45% had ever had a pelvic exam. The mean interval between sexual debut and initial pelvic exam (our proxy for gynecologic care) was 13.3 months (range = 0-70 months, SD = 11.8 months). Cox proportional hazard modeling identified four predictors of time to first pelvic exam: experience of sexually transmitted infection (STI) or pregnancy (hazard ratio [HR] = 1.9), having disclosed sexual activity to any clinician (HR = 1.7), access to confidential care (HR = 3.1), and high self-efficacy for accessing confidential care (HR = 2.1).

CONCLUSIONS

Most sexually active girls have not told a clinician that they are sexually active and many have not had counseling related to sexual health. Delay between sexual debut and initial pelvic exam is substantial for low-income urban girls, and often occurs in reaction to pregnancy or STI. Setting of usual care does not predict timely gynecologic care, but access to confidential care does.

Determinants of functional outcome after simple and complex acetabular fractures involving the posterior wall

We have evaluated the functional, clinical and radiological outcome of patients with simple and complex acetabular fractures involving the posterior wall, and identified factors associated with an adverse outcome. We reviewed 128 patients treated operatively for a fracture involving the posterior wall of the acetabulum between 1982 and 1999. The Musculoskeletal Functional Assessment and Short-Form 36 scores, the presence of radiological arthritis and complications were assessed as a function of injury, treatment and clinical variables. The patients had profound functional deficits compared with the normal population. Anatomical reduction alone was not sufficient to restore function. The fracture pattern, marginal impaction and residual displacement of > 2 mm were associated with the development of arthritis, which related to poor function and the need for hip replacement. It may be appropriate to consider immediate total hip replacement for patients aged > 50 years with marginal impaction and comminution of the wall, since 7 of 13 (54%) of these required early hip replacement.

Hierarchies of Extracellular Matrix and Mineral Organization in Bone of the Craniofacial Complex and Skeleton

Structural hierarchies are common in biologic systems and are particularly evident in biomineralized structures. In the craniofacial complex and skeleton of vertebrates, extracellular matrix and mineral of bone are structurally ordered at many dimensional scales from the macro level to the nano level. Indeed, the nanocomposite texture of bone, with nanocrystals of apatitic mineral embedded within a crosslinked matrix of fibrillar and nonfibrillar proteins, imparts to bone the very mechanical properties and toughness it needs to function in vital organ protection, musculoskeletal movement and mastication. This article focuses on how hierarchies of extracellular matrix protein organization influence bone cell behavior, tissue architecture and mineralization. Additional attention is given to recent work on the molecular determinants of mineral induction in bone, and how the mineralization process is subsequently regulated by inhibitory proteins.