Joan Hilton - Academia.edu (original) (raw)

Papers by Joan Hilton

American Journal of Public Health, Sep 1, 2010

AIDS Research and Human Retroviruses, 2014

Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV preve... more Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV prevention, but results from clinical trials have been largely disappointing. We postulated that unrecognized effects of intravaginal gels on the upper female reproductive tract might contribute to the lower-than-expected efficacy of HIV microbicides. Our objective was to study the effects of intravaginal gels on the immune microenvironment of the cervix and uterus. In this randomized crossover study, 27 healthy female volunteers used a nightly application of intravaginal nonoxynol-9 (N9) gel as a "failed" microbicide or the universal placebo gel (UPG) as a "safe" gel (intervention cycles), or nothing (control cycle) from the end of menses to the mid-luteal phase. At a specific time-point following ovulation, all participants underwent sample collection for measurements of T-cell phenotypes, gene expression, and cytokine/chemokine protein concentrations from 3 anatomic sites above the vagina: the cervical transformation zone, the endocervix and the endometrium. We used hierarchical statistical models to estimate mean (95% CI) intervention effects, for N9 and UPG relative to control. Exposure to N9 gel and UPG generated a common "harm signal" that included transcriptional up-regulation of inflammatory genes chemokine (C-C motif) ligand 20 (macrophage inflammatory factor-3alpha) and interleukin 8 in the cervix, decreased protein concentrations of secretory leukocyte protease inhibitor, and transcriptional up-regulation of inflammatory mediators glycodelin-A and osteopontin in the endometrium. These results need to be replicated with a larger sample, but underscore the need to consider the effects of microbicide agents and gel excipients on the upper female reproductive tract in studies of vaginal microbicides.

PLoS ONE, 2012

Background: Personal health records (PHR) may improve patients' health by providing access to and... more Background: Personal health records (PHR) may improve patients' health by providing access to and context for health information. Among patients receiving care at a safety-net HIV/AIDS clinic, we examined the hypothesis that a mental health (MH) or substance use (SU) condition represents a barrier to engagement with web-based health information, as measured by consent to participate in a trial that provided access to personal (PHR) or general (non-PHR) health information portals and by completion of baseline study surveys posted there.

Medical Care, 2006

Maintaining independence in daily functioning is an important health outcome in older adults. A k... more Maintaining independence in daily functioning is an important health outcome in older adults. A key measure of functional independence in elders is the ability to do activities of daily living (ADL) without the assistance of another person. However, few prognostic indices have been developed that stratify elders into groups at variable risk for developing ADL dependence. We sought to develop and validate a prognostic index that distinguishes between elders at different risk of ADL dependence. We studied subjects enrolled in Asset and Health Dynamics Among the Oldest Old (AHEAD), a nationally representative cohort of elders older than the age of 70. We included 5239 subjects (mean age, 77) reporting that they could do each of 5 ADL (bathing, dressing, toileting, transferring, and eating) without the assistance of another person at baseline. Subjects were divided into development (n = 3245) and validation (n = 1994) samples based on region of the United States. Our primary outcome was the need for help (dependence) with at least one ADL at 2 years. We used logistic regression to select among predictor variables encompassing several domains: demographic characteristics, comorbid conditions, functional status, cognitive status, and general health indicators. The 9 independent predictors of 2-year ADL dependence were age older than 80, diabetes, difficulty walking several blocks, difficulty bathing or dressing, need for help with personal finances, difficulty lifting 10 pounds, inability to name the Vice President, history of falling, and low body mass index. We created a risk score by assigning 1 point to each risk factor. In the development sample, rates of 2-year ADL dependence in subjects with 0, 1, 2, 3, 4, and 5 or more risk factors were 1.3%, 2.8%, 3.8%, 10%, 22%, and 33%, respectively (P < 0.001, roc area = 0.79). In the validation sample, the rates were 0.7%, 4.3%, 8.7%, 11%, 18%, and 40% (P < 0.001, roc area = 0.77). The risk score also discriminated between subjects at variable risk for a combined outcome of either ADL decline or death (4.3%, 7.6%, 15%, 21%, 30%, and 47%). Using data available from patient reports, we validated a simple risk index that distinguished between elders at variable risk of ADL dependence. This index may be useful for identifying elders at high risk of poor outcomes or for risk adjustment.

Journal of the American Medical Informatics Association, 2010

Personal health records (PHRs) are information repositories; however, PHRs may be less available ... more Personal health records (PHRs) are information repositories; however, PHRs may be less available to persons in the safety net setting. We deployed a free, secure, internet-based PHR for persons receiving care at the AIDS/HIV clinic at San Francisco General Hospital. In our initial rollout, 221 persons registered for the PHR. Compared to the entire clinic, these initial users were more likely to be Caucasian, male, non-Hispanic, on antiretroviral medications, and have better control of their HIV infection. The median number of online sessions was 7 and the median session length was 4 min. Laboratory results were the most commonly accessed feature. Patients were satisfied with the PHR and more than 80% of users agreed that the PHR helped them manage their medical problems; however, some users were concerned that their health information was not accurate or secure. Patients in a safety net setting will access and use an online PHR.

Journal of the American Dental Association, 1995

Diagnostic tests may be necessary to determine the cause of oral ulcers. Direct immunofluorescenc... more Diagnostic tests may be necessary to determine the cause of oral ulcers. Direct immunofluorescence staining of oral smears supplies results much more quickly than viral culture, the "gold standard" for diagnosing HSV lesions. This study compares the sensitivity and specificity of direct immunofluorescence staining vs. viral culture and evaluates the usefulness of the two techniques for the general dental practitioner.

Journal of Periodontology, 1994

Objective, reliable, and valid diagnostic criteria are required for studies of HIV-associated per... more Objective, reliable, and valid diagnostic criteria are required for studies of HIV-associated periodontal conditions. A set of diagnostic criteria were devised based on a literature review and the clinical experience of the authors. Validity was assessed by comparison with clinical photographs and the criteria were evaluated and refined for ease of use and objectivity. To assess the reliability of the criteria, 9 experienced examiners were shown 20 clinical photographs accompanied by brief vignettes of clinical information. Each examiner was asked to identify signs evident in a particular area of the photograph and to record a diagnosis. Five examiners were then trained and calibrated in the use of the criteria. Finally, all 9 examiners were shown the original 20 photographs and asked to identify signs and record diagnoses. The examiners showed only fair reliability in the recognition of clinical signs, made diagnoses intuitively, and had only fair agreement on the diagnosis of periodontal diseases. The inter-examiner reliability of examiners trained and calibrated in the use of the criteria increased and was greater than among untrained examiners. Rigid diagnostic criteria are essential in epidemiologic studies. Inter-examiner reliability will be increased if examiners are trained in their use and calibrated in the recognition of clinical signs. Diagnostic criteria should be modified as understanding of the diseases they classify increases. The proposed criteria will enhance the value of studies of HIV-associated periodontal changes and will contribute to that understanding.

Journal of Biomedical Materials Research, 2002

Dentin structure and properties are known to vary with orientation and location. The present stud... more Dentin structure and properties are known to vary with orientation and location. The present study explored the variation in the ultimate tensile strength (UTS) of dentin with location in the tooth. Hourglass specimens were prepared from dentin located in the center, under cusps, and in the cervical regions of human molar teeth. These were tested in tension at various distances from the pulp. Median tensile strengths ranged from 44.4 MPa in the inner dentin near the pulp, to 97.8 MPa near the dentino-enamel junction (DEJ). This increase in the median UTS with distance from the pulp to the DEJ was statistically significant (P <.001). Of particular importance was the observation that the UTS measurements followed a Weibull probability distribution, with a Weibull modulus of about 4.5. The Weibull behavior of the UTS data strongly suggests that the large variances in fracture strength data result from a distribution of preexisting defects in the dentin. These findings justify a damage-mechanics approach to studies of dentin failure.

Journal of Adolescent Health, 2001

Methods: Participants in Reaching for Excellence in Adolescent Care and Health (REACH), a multice... more Methods: Participants in Reaching for Excellence in Adolescent Care and Health (REACH), a multicenter longitudinal observational study of HIV/AIDS in adolescents, received physical examinations, blood tests, and oral examinations at 3-month intervals. We evaluated participants for oral conditions commonly seen in relationship to HIV, and explored the association of the most common lesion with selected biological and behavioral variables at baseline using contingency tables and Fisher's Exact test.

Emerging Infectious Diseases, 2002

We conducted a randomized, triple-blinded home drinking water intervention trial to determine if ... more We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was Ahighly credible gastrointestinal illness@ (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention.

Controlled Clinical Trials, 2004

Double-blinded trials are often considered the gold standard for research, but significant bias m... more Double-blinded trials are often considered the gold standard for research, but significant bias may result from unblinding of participants and investigators. Although the CONSORT guidelines discuss the importance of reporting "evidence that blinding was successful", it is unclear what constitutes appropriate evidence. Among studies reporting methods to evaluate blinding effectiveness, many have compared groups with respect to the proportions correctly identifying their intervention at the end of the trial. Instead, we reasoned that participants' beliefs, and not their correctness, are more directly associated with potential bias, especially in relation to self-reported health outcomes. During the Water Evaluation Trial performed in northern California in 1999, we investigated blinding effectiveness by sequential interrogation of participants about their "blinded" intervention assignment (active or placebo). Irrespective of group, participants showed a strong tendency to believe they had been assigned to the active intervention; this translated into a statistically significant intergroup difference in the correctness of participants' beliefs, even at the start of the trial before unblinding had a chance to occur. In addition, many participants (31%) changed their belief during the trial, suggesting that assessment of belief at a single time does not capture unblinding. Sequential measures based on either two or all eight questionnaires identified significant group-related differences in belief patterns that were not identified by the single, cross-sectional measure. In view of the relative insensitivity of cross-sectional measures, the minimal additional information in more than two assessments of beliefs and the risk of modifying participants' beliefs by repeated questioning, we conclude that the optimal means of assessing unblinding is an intergroup comparison of the change in beliefs (and not their correctness) between the start and end of a randomized controlled trial.

Community Dentistry and Oral Epidemiology, 2004

This single-blind randomized controlled pilot study evaluated the efficacy of a behavioral interv... more This single-blind randomized controlled pilot study evaluated the efficacy of a behavioral intervention program, PRO-SELF: Candidiasis, to reduce time to recurrence of oral candidiasis over 6 months in susceptible HIV-seropositive persons. The intervention involved instruction by dentists on improving oral hygiene, minimizing sugar intake, and self-diagnosing candidiasis. Participants were adults with oral candidiasis responsive to antifungals who presented to the UCSF Stomatology Clinic between 1997 and 2000. At 2-3 weeks of follow-up visits, a dentist "examiner", masked to group assignment, quizzed participants as to the presence of candidiasis, and assessed candidiasis status. A second, unmasked dentist "instructor" then delivered the program to intervention participants. Participants recorded dietary and oral hygiene practices in 24-h recall diaries: intervention participants at each visit and controls at initial and final visits. At randomization, CD4+ cell counts (cells/mm(3)) were 298 +/- 188 among 18 intervention participants and 396 +/- 228 among 17 controls. The candidiasis recurrence rates at 6 months were 78% among intervention compared with 88% among control participants (hazard ratio 0.72; 95% CI 0.35-1.50). Performing oral hygiene after meals/snacks showed the largest relative improvement: intervention-control difference in proportion of meals/snacks affected was 24% (95% CI -1 to 48%). Self-diagnoses of candidiasis were inaccurate, possibly because of mild episodes. The results weakly indicate that regular instruction from healthcare professionals helps patients delay candidiasis recurrence by improving oral hygiene. Among HIV-seropositive persons, those with poor oral hygiene, and high-sugar diets are most likely to benefit.

Community Dentistry and Oral Epidemiology, 2001

To determine if medical clinicians are as accurate as dental clinicians in recognizing diagnostic... more To determine if medical clinicians are as accurate as dental clinicians in recognizing diagnostic characteristics of HIV-related oral lesions. In 355 HIV-infected participants at five Women's Interagency HIV Study sites, we paired oral examinations conducted within 7 days of each other by dental and medical clinicians. We used the former as a gold standard against which to evaluate the accuracy of the latter. We assessed the accuracy of the medical clinicians' findings based both on their observations of abnormalities and on their descriptions of these abnormalities. Dental clinicians diagnosed some oral abnormality in 38% of participants. When "abnormality" was used as the medical clinicians' outcome, sensitivities were 75% for pseudomembranous candidiasis and 58% for erythematous candidiasis, but only 40% for hairy leukoplakia. When a precise description of the abnormality was used as their outcome, sensitivities were 19%, 12% and 20%, respectively. Medical clinicians recognize that HIV-related oral abnormalities are present in 40-75% of cases, but less often describe them accurately. Low sensitivity implies that the true associations of specific oral lesions with other HIV phenomena, such as time until AIDS, must be stronger than the literature suggests.

Annals of Emergency Medicine, 2010

Background: Patients awaiting inpatient beds staying in the emergency department (ED) are the pri... more Background: Patients awaiting inpatient beds staying in the emergency department (ED) are the primary cause of ED crowding worldwide. In the competing demand for beds between scheduled and emergency admissions, many hospitalists and administrators still consider "normal" that those patients who seek inpatient care through ED must lose out, although it could negatively affect their quality outcomes.

Journal of dental …, 2002

Abstract: This paper reviews five randomized controlled trials of brief spit (smokeless) tobacco ... more Abstract: This paper reviews five randomized controlled trials of brief spit (smokeless) tobacco (ST) cessation treatment by dental professionals consisting of oral cancer screening, cessation advice, self-help materials, and brief cessation counseling by a dental hygienist. In ...

American Journal of Public Health, 2010

Page 1. LETTERS QUESTIONABLE INCREASE OF CHILDHOOD LEUKEMIA IN BASRAH, IRAQ The explosion of depl... more Page 1. LETTERS QUESTIONABLE INCREASE OF CHILDHOOD LEUKEMIA IN BASRAH, IRAQ The explosion of depleted uranium ammuni-tion generates ultrafine uranium dust parti-cles that may pose health hazards, especially ...

American Journal of Public Health, 2009

We estimated the relative rate of highly credible gastrointestinal illness (HCGI) per year associ... more We estimated the relative rate of highly credible gastrointestinal illness (HCGI) per year associated with active versus sham household water filtration devices among older adults in a community receiving tap water meeting current US standards. We conducted a randomized, triple-blinded, crossover trial in 714 households (988 individuals), which used active and sham water filtration devices for 6 months each. We estimated the annual incidence rate ratio of HCGI episodes and the longitudinal prevalence ratio of HCGI days at population and individual levels with a generalized estimating equation (GEE) and generalized linear mixed models (GLMMs), respectively, adjusted for covariates associated with outcome. The incidence rate ratios (active versus sham) were 0.88 (95% confidence interval [CI] = 0.77, 1.00) and 0.85 (95% CI = 0.76, 0.94) HCGI episodes per year estimated by GEE and GLMM models, respectively. The corresponding longitudinal prevalence ratios were 0.88 (95% CI = 0.74, 1.05) and 0.84 (95% CI = 0.78, 0.90) HCGI days per person per year. We observed reductions in population- and individual-level measures of HCGI associated with use of the active filtration device. These findings suggest the need for further research on the impact of drinking water on the health of sensitive subpopulations.

American Journal of Obstetrics and Gynecology, 2008

OBJECTIVE: Evidence suggests increased risk of fetal cerebral hypoxemia in CHD. Hypoxic brain inj... more OBJECTIVE: Evidence suggests increased risk of fetal cerebral hypoxemia in CHD. Hypoxic brain injury could lead to poor brain growth and development. The risk of poor fetal brain growth as determined by newborn microcephaly was ascertained in isolated CHD.

Aids, 1994

We evaluated time from HIV seroconversion to diagnosis of two common oral lesions associated with... more We evaluated time from HIV seroconversion to diagnosis of two common oral lesions associated with HIV infection and disease progression. Oral examinations were performed on homosexual and bisexual men enrolled in prospective cohorts. Homosexual and bisexual men were followed in three epidemiologic cohort studies in San Francisco, California, USA. Data were evaluated from 80 men with well-defined dates of HIV seroconversion from 1984 through 1991. We determined the cumulative incidence of oral candidiasis and hairy leukoplakia after HIV seroconversion. Four per cent of men developed oral candidiasis within 1 year after HIV seroconversion, 8% within 2, 15% within 3, 18% within 4, and 26% within 5 years. Nine per cent developed hairy leukoplakia within 1 year, 16% within 2, 25% within 3, 35% within 4, and 42% within 5 years. The median CD4+ count was 391 x 10(6)/l when oral candidiasis was first reported and 468 x 10(6)/l when hairy leukoplakia was first reported. Oral candidiasis or hairy leukoplakia appeared in a significant proportion of HIV-infected homosexual and bisexual men. These lesions occurred relatively soon after HIV seroconversion, typically before AIDS. Evaluation of HIV-infected individuals for these lesions has many potential clinical and research benefits, including the possible use of oral lesions as primary end-points in clinical trials.

American Journal of Public Health, Sep 1, 2010

AIDS Research and Human Retroviruses, 2014

Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV preve... more Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV prevention, but results from clinical trials have been largely disappointing. We postulated that unrecognized effects of intravaginal gels on the upper female reproductive tract might contribute to the lower-than-expected efficacy of HIV microbicides. Our objective was to study the effects of intravaginal gels on the immune microenvironment of the cervix and uterus. In this randomized crossover study, 27 healthy female volunteers used a nightly application of intravaginal nonoxynol-9 (N9) gel as a "failed" microbicide or the universal placebo gel (UPG) as a "safe" gel (intervention cycles), or nothing (control cycle) from the end of menses to the mid-luteal phase. At a specific time-point following ovulation, all participants underwent sample collection for measurements of T-cell phenotypes, gene expression, and cytokine/chemokine protein concentrations from 3 anatomic sites above the vagina: the cervical transformation zone, the endocervix and the endometrium. We used hierarchical statistical models to estimate mean (95% CI) intervention effects, for N9 and UPG relative to control. Exposure to N9 gel and UPG generated a common "harm signal" that included transcriptional up-regulation of inflammatory genes chemokine (C-C motif) ligand 20 (macrophage inflammatory factor-3alpha) and interleukin 8 in the cervix, decreased protein concentrations of secretory leukocyte protease inhibitor, and transcriptional up-regulation of inflammatory mediators glycodelin-A and osteopontin in the endometrium. These results need to be replicated with a larger sample, but underscore the need to consider the effects of microbicide agents and gel excipients on the upper female reproductive tract in studies of vaginal microbicides.

PLoS ONE, 2012

Background: Personal health records (PHR) may improve patients' health by providing access to and... more Background: Personal health records (PHR) may improve patients' health by providing access to and context for health information. Among patients receiving care at a safety-net HIV/AIDS clinic, we examined the hypothesis that a mental health (MH) or substance use (SU) condition represents a barrier to engagement with web-based health information, as measured by consent to participate in a trial that provided access to personal (PHR) or general (non-PHR) health information portals and by completion of baseline study surveys posted there.

Medical Care, 2006

Maintaining independence in daily functioning is an important health outcome in older adults. A k... more Maintaining independence in daily functioning is an important health outcome in older adults. A key measure of functional independence in elders is the ability to do activities of daily living (ADL) without the assistance of another person. However, few prognostic indices have been developed that stratify elders into groups at variable risk for developing ADL dependence. We sought to develop and validate a prognostic index that distinguishes between elders at different risk of ADL dependence. We studied subjects enrolled in Asset and Health Dynamics Among the Oldest Old (AHEAD), a nationally representative cohort of elders older than the age of 70. We included 5239 subjects (mean age, 77) reporting that they could do each of 5 ADL (bathing, dressing, toileting, transferring, and eating) without the assistance of another person at baseline. Subjects were divided into development (n = 3245) and validation (n = 1994) samples based on region of the United States. Our primary outcome was the need for help (dependence) with at least one ADL at 2 years. We used logistic regression to select among predictor variables encompassing several domains: demographic characteristics, comorbid conditions, functional status, cognitive status, and general health indicators. The 9 independent predictors of 2-year ADL dependence were age older than 80, diabetes, difficulty walking several blocks, difficulty bathing or dressing, need for help with personal finances, difficulty lifting 10 pounds, inability to name the Vice President, history of falling, and low body mass index. We created a risk score by assigning 1 point to each risk factor. In the development sample, rates of 2-year ADL dependence in subjects with 0, 1, 2, 3, 4, and 5 or more risk factors were 1.3%, 2.8%, 3.8%, 10%, 22%, and 33%, respectively (P < 0.001, roc area = 0.79). In the validation sample, the rates were 0.7%, 4.3%, 8.7%, 11%, 18%, and 40% (P < 0.001, roc area = 0.77). The risk score also discriminated between subjects at variable risk for a combined outcome of either ADL decline or death (4.3%, 7.6%, 15%, 21%, 30%, and 47%). Using data available from patient reports, we validated a simple risk index that distinguished between elders at variable risk of ADL dependence. This index may be useful for identifying elders at high risk of poor outcomes or for risk adjustment.

Journal of the American Medical Informatics Association, 2010

Personal health records (PHRs) are information repositories; however, PHRs may be less available ... more Personal health records (PHRs) are information repositories; however, PHRs may be less available to persons in the safety net setting. We deployed a free, secure, internet-based PHR for persons receiving care at the AIDS/HIV clinic at San Francisco General Hospital. In our initial rollout, 221 persons registered for the PHR. Compared to the entire clinic, these initial users were more likely to be Caucasian, male, non-Hispanic, on antiretroviral medications, and have better control of their HIV infection. The median number of online sessions was 7 and the median session length was 4 min. Laboratory results were the most commonly accessed feature. Patients were satisfied with the PHR and more than 80% of users agreed that the PHR helped them manage their medical problems; however, some users were concerned that their health information was not accurate or secure. Patients in a safety net setting will access and use an online PHR.

Journal of the American Dental Association, 1995

Diagnostic tests may be necessary to determine the cause of oral ulcers. Direct immunofluorescenc... more Diagnostic tests may be necessary to determine the cause of oral ulcers. Direct immunofluorescence staining of oral smears supplies results much more quickly than viral culture, the "gold standard" for diagnosing HSV lesions. This study compares the sensitivity and specificity of direct immunofluorescence staining vs. viral culture and evaluates the usefulness of the two techniques for the general dental practitioner.

Journal of Periodontology, 1994

Objective, reliable, and valid diagnostic criteria are required for studies of HIV-associated per... more Objective, reliable, and valid diagnostic criteria are required for studies of HIV-associated periodontal conditions. A set of diagnostic criteria were devised based on a literature review and the clinical experience of the authors. Validity was assessed by comparison with clinical photographs and the criteria were evaluated and refined for ease of use and objectivity. To assess the reliability of the criteria, 9 experienced examiners were shown 20 clinical photographs accompanied by brief vignettes of clinical information. Each examiner was asked to identify signs evident in a particular area of the photograph and to record a diagnosis. Five examiners were then trained and calibrated in the use of the criteria. Finally, all 9 examiners were shown the original 20 photographs and asked to identify signs and record diagnoses. The examiners showed only fair reliability in the recognition of clinical signs, made diagnoses intuitively, and had only fair agreement on the diagnosis of periodontal diseases. The inter-examiner reliability of examiners trained and calibrated in the use of the criteria increased and was greater than among untrained examiners. Rigid diagnostic criteria are essential in epidemiologic studies. Inter-examiner reliability will be increased if examiners are trained in their use and calibrated in the recognition of clinical signs. Diagnostic criteria should be modified as understanding of the diseases they classify increases. The proposed criteria will enhance the value of studies of HIV-associated periodontal changes and will contribute to that understanding.

Journal of Biomedical Materials Research, 2002

Dentin structure and properties are known to vary with orientation and location. The present stud... more Dentin structure and properties are known to vary with orientation and location. The present study explored the variation in the ultimate tensile strength (UTS) of dentin with location in the tooth. Hourglass specimens were prepared from dentin located in the center, under cusps, and in the cervical regions of human molar teeth. These were tested in tension at various distances from the pulp. Median tensile strengths ranged from 44.4 MPa in the inner dentin near the pulp, to 97.8 MPa near the dentino-enamel junction (DEJ). This increase in the median UTS with distance from the pulp to the DEJ was statistically significant (P <.001). Of particular importance was the observation that the UTS measurements followed a Weibull probability distribution, with a Weibull modulus of about 4.5. The Weibull behavior of the UTS data strongly suggests that the large variances in fracture strength data result from a distribution of preexisting defects in the dentin. These findings justify a damage-mechanics approach to studies of dentin failure.

Journal of Adolescent Health, 2001

Methods: Participants in Reaching for Excellence in Adolescent Care and Health (REACH), a multice... more Methods: Participants in Reaching for Excellence in Adolescent Care and Health (REACH), a multicenter longitudinal observational study of HIV/AIDS in adolescents, received physical examinations, blood tests, and oral examinations at 3-month intervals. We evaluated participants for oral conditions commonly seen in relationship to HIV, and explored the association of the most common lesion with selected biological and behavioral variables at baseline using contingency tables and Fisher's Exact test.

Emerging Infectious Diseases, 2002

We conducted a randomized, triple-blinded home drinking water intervention trial to determine if ... more We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was Ahighly credible gastrointestinal illness@ (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention.

Controlled Clinical Trials, 2004

Double-blinded trials are often considered the gold standard for research, but significant bias m... more Double-blinded trials are often considered the gold standard for research, but significant bias may result from unblinding of participants and investigators. Although the CONSORT guidelines discuss the importance of reporting "evidence that blinding was successful", it is unclear what constitutes appropriate evidence. Among studies reporting methods to evaluate blinding effectiveness, many have compared groups with respect to the proportions correctly identifying their intervention at the end of the trial. Instead, we reasoned that participants' beliefs, and not their correctness, are more directly associated with potential bias, especially in relation to self-reported health outcomes. During the Water Evaluation Trial performed in northern California in 1999, we investigated blinding effectiveness by sequential interrogation of participants about their "blinded" intervention assignment (active or placebo). Irrespective of group, participants showed a strong tendency to believe they had been assigned to the active intervention; this translated into a statistically significant intergroup difference in the correctness of participants' beliefs, even at the start of the trial before unblinding had a chance to occur. In addition, many participants (31%) changed their belief during the trial, suggesting that assessment of belief at a single time does not capture unblinding. Sequential measures based on either two or all eight questionnaires identified significant group-related differences in belief patterns that were not identified by the single, cross-sectional measure. In view of the relative insensitivity of cross-sectional measures, the minimal additional information in more than two assessments of beliefs and the risk of modifying participants' beliefs by repeated questioning, we conclude that the optimal means of assessing unblinding is an intergroup comparison of the change in beliefs (and not their correctness) between the start and end of a randomized controlled trial.

Community Dentistry and Oral Epidemiology, 2004

This single-blind randomized controlled pilot study evaluated the efficacy of a behavioral interv... more This single-blind randomized controlled pilot study evaluated the efficacy of a behavioral intervention program, PRO-SELF: Candidiasis, to reduce time to recurrence of oral candidiasis over 6 months in susceptible HIV-seropositive persons. The intervention involved instruction by dentists on improving oral hygiene, minimizing sugar intake, and self-diagnosing candidiasis. Participants were adults with oral candidiasis responsive to antifungals who presented to the UCSF Stomatology Clinic between 1997 and 2000. At 2-3 weeks of follow-up visits, a dentist "examiner", masked to group assignment, quizzed participants as to the presence of candidiasis, and assessed candidiasis status. A second, unmasked dentist "instructor" then delivered the program to intervention participants. Participants recorded dietary and oral hygiene practices in 24-h recall diaries: intervention participants at each visit and controls at initial and final visits. At randomization, CD4+ cell counts (cells/mm(3)) were 298 +/- 188 among 18 intervention participants and 396 +/- 228 among 17 controls. The candidiasis recurrence rates at 6 months were 78% among intervention compared with 88% among control participants (hazard ratio 0.72; 95% CI 0.35-1.50). Performing oral hygiene after meals/snacks showed the largest relative improvement: intervention-control difference in proportion of meals/snacks affected was 24% (95% CI -1 to 48%). Self-diagnoses of candidiasis were inaccurate, possibly because of mild episodes. The results weakly indicate that regular instruction from healthcare professionals helps patients delay candidiasis recurrence by improving oral hygiene. Among HIV-seropositive persons, those with poor oral hygiene, and high-sugar diets are most likely to benefit.

Community Dentistry and Oral Epidemiology, 2001

To determine if medical clinicians are as accurate as dental clinicians in recognizing diagnostic... more To determine if medical clinicians are as accurate as dental clinicians in recognizing diagnostic characteristics of HIV-related oral lesions. In 355 HIV-infected participants at five Women's Interagency HIV Study sites, we paired oral examinations conducted within 7 days of each other by dental and medical clinicians. We used the former as a gold standard against which to evaluate the accuracy of the latter. We assessed the accuracy of the medical clinicians' findings based both on their observations of abnormalities and on their descriptions of these abnormalities. Dental clinicians diagnosed some oral abnormality in 38% of participants. When "abnormality" was used as the medical clinicians' outcome, sensitivities were 75% for pseudomembranous candidiasis and 58% for erythematous candidiasis, but only 40% for hairy leukoplakia. When a precise description of the abnormality was used as their outcome, sensitivities were 19%, 12% and 20%, respectively. Medical clinicians recognize that HIV-related oral abnormalities are present in 40-75% of cases, but less often describe them accurately. Low sensitivity implies that the true associations of specific oral lesions with other HIV phenomena, such as time until AIDS, must be stronger than the literature suggests.

Annals of Emergency Medicine, 2010

Background: Patients awaiting inpatient beds staying in the emergency department (ED) are the pri... more Background: Patients awaiting inpatient beds staying in the emergency department (ED) are the primary cause of ED crowding worldwide. In the competing demand for beds between scheduled and emergency admissions, many hospitalists and administrators still consider "normal" that those patients who seek inpatient care through ED must lose out, although it could negatively affect their quality outcomes.

Journal of dental …, 2002

Abstract: This paper reviews five randomized controlled trials of brief spit (smokeless) tobacco ... more Abstract: This paper reviews five randomized controlled trials of brief spit (smokeless) tobacco (ST) cessation treatment by dental professionals consisting of oral cancer screening, cessation advice, self-help materials, and brief cessation counseling by a dental hygienist. In ...

American Journal of Public Health, 2010

Page 1. LETTERS QUESTIONABLE INCREASE OF CHILDHOOD LEUKEMIA IN BASRAH, IRAQ The explosion of depl... more Page 1. LETTERS QUESTIONABLE INCREASE OF CHILDHOOD LEUKEMIA IN BASRAH, IRAQ The explosion of depleted uranium ammuni-tion generates ultrafine uranium dust parti-cles that may pose health hazards, especially ...

American Journal of Public Health, 2009

We estimated the relative rate of highly credible gastrointestinal illness (HCGI) per year associ... more We estimated the relative rate of highly credible gastrointestinal illness (HCGI) per year associated with active versus sham household water filtration devices among older adults in a community receiving tap water meeting current US standards. We conducted a randomized, triple-blinded, crossover trial in 714 households (988 individuals), which used active and sham water filtration devices for 6 months each. We estimated the annual incidence rate ratio of HCGI episodes and the longitudinal prevalence ratio of HCGI days at population and individual levels with a generalized estimating equation (GEE) and generalized linear mixed models (GLMMs), respectively, adjusted for covariates associated with outcome. The incidence rate ratios (active versus sham) were 0.88 (95% confidence interval [CI] = 0.77, 1.00) and 0.85 (95% CI = 0.76, 0.94) HCGI episodes per year estimated by GEE and GLMM models, respectively. The corresponding longitudinal prevalence ratios were 0.88 (95% CI = 0.74, 1.05) and 0.84 (95% CI = 0.78, 0.90) HCGI days per person per year. We observed reductions in population- and individual-level measures of HCGI associated with use of the active filtration device. These findings suggest the need for further research on the impact of drinking water on the health of sensitive subpopulations.

American Journal of Obstetrics and Gynecology, 2008

OBJECTIVE: Evidence suggests increased risk of fetal cerebral hypoxemia in CHD. Hypoxic brain inj... more OBJECTIVE: Evidence suggests increased risk of fetal cerebral hypoxemia in CHD. Hypoxic brain injury could lead to poor brain growth and development. The risk of poor fetal brain growth as determined by newborn microcephaly was ascertained in isolated CHD.

Aids, 1994

We evaluated time from HIV seroconversion to diagnosis of two common oral lesions associated with... more We evaluated time from HIV seroconversion to diagnosis of two common oral lesions associated with HIV infection and disease progression. Oral examinations were performed on homosexual and bisexual men enrolled in prospective cohorts. Homosexual and bisexual men were followed in three epidemiologic cohort studies in San Francisco, California, USA. Data were evaluated from 80 men with well-defined dates of HIV seroconversion from 1984 through 1991. We determined the cumulative incidence of oral candidiasis and hairy leukoplakia after HIV seroconversion. Four per cent of men developed oral candidiasis within 1 year after HIV seroconversion, 8% within 2, 15% within 3, 18% within 4, and 26% within 5 years. Nine per cent developed hairy leukoplakia within 1 year, 16% within 2, 25% within 3, 35% within 4, and 42% within 5 years. The median CD4+ count was 391 x 10(6)/l when oral candidiasis was first reported and 468 x 10(6)/l when hairy leukoplakia was first reported. Oral candidiasis or hairy leukoplakia appeared in a significant proportion of HIV-infected homosexual and bisexual men. These lesions occurred relatively soon after HIV seroconversion, typically before AIDS. Evaluation of HIV-infected individuals for these lesions has many potential clinical and research benefits, including the possible use of oral lesions as primary end-points in clinical trials.