Repeated topical treatment, in contrast to single oral doses, with Vitamin A-containing preparations does not affect plasma concentrations of retinol, retinyl esters or retinoic acids in female subjects of child-bearing age

BACKGROUND

Vitamin A is widely used in cosmetic preparations. Given that oral Vitamin A and its metabolites present a potential reproductive risk, the present study investigated the effect of topical Vitamin A on human endogenous plasma levels of Vitamin A and its metabolites.

METHODS

Two groups of 14 female volunteers of child-bearing age were kept on a Vitamin A-poor diet and treated topically for 21 days with creams containing 0.30% retinol or 0.55% retinyl palmitate on approximately 3000 cm2 of their body surface area, amounting to a total of approximately 30,000 IU Vitamin A/subject/day. After a 12-day wash-out period, the study groups received single oral doses of 10,000 IU or 30,000 IU retinyl palmitate (RP), corresponding to the maximal EU allowance during pregnancy or three-times higher, respectively. Blood samples were collected over 24h on study days -3 (pre-study), 1, 21 (first and last days of topical treatment) and 34 (oral administration) at 0, 1, 2, 4, 6, 8, 12, 14-16 h and 24 h after treatment for determination of plasma concentrations of retinol (REL), retinyl palmitate (RP), oleate (RO) and stearate (RS), 9-cis-, 13-cis-, all-trans- (AT), 13-cis-4-oxo- or AT-4-oxo-retinoic acids (RAs).

RESULTS

With the exception of transient mild (RP-group) to moderate (REL-group) local irritation on the treatment sites, no adverse local or systemic effects were noted. On days 1 or 21 of topical treatment, no changes were measured in individual or group mean plasma Cmax, AUC0-24 h or other pharmacokinetic parameters of REL, retinyl esters or RAs relative to pre-study data. In contrast, single oral doses of RP at 10,000 IU or 30,000 IU produced dose-related and sustained increases in Cmax and AUC0-24 h values of plasma RP, RO, RS, 13-cis- and 13-cis-4-oxo-RAs, as well as a transient increase in AT-RA. In conclusion, our results provide evidence that human topical exposure to retinol- or retinyl ester-containing cosmetic creams at 30,000 IU/day and maximal use concentrations do not affect plasma levels of retinol, retinyl esters or RAs, whereas single oral doses at 10,000 IU or 30,000 IU produce significant increases in plasma retinyl esters and RAs.

An assessment of the phototoxic hazard of a personal product ingredient using in vitro assays

Where substances are intended for use in personal products applied to the skin an assessment of potential phototoxic hazard is required. This report describes a tiered testing strategy involving in vitro assays used for the phototoxic hazard assessment of a personal product ingredient (Ingredient X). The initial assay was measurement of a UV/visible absorption spectrum to identify absorption at relevant wavelengths. This was followed by in vitro assays for phototoxicity (3T3 cell neutral red uptake phototoxicity test) and photoallergy (photobinding to human serum albumin). These in vitro screens gave equivocal results for Ingredient X which appeared to suggest a weak phototoxic reaction. To further evaluate the phototoxic hazard of Ingredient X to human skin, a phototoxicity assay using a 3-D human skin model was conducted. Ingredient X did not cause phototoxicity in this assay. Overall conclusions from these studies were that although Ingredient X showed slight intrinsic potential for photoactivation, it was unlikely to present a hazard to human skin. This report illustrates the value in a step-wise strategy of the use of human skin models to help interpret the results of other in vitro phototoxicity assays.

An evidence-based review of patient-centered behavioral interventions for hypertension

INTRODUCTION

While behavioral interventions may be viewed as important strategies to improve blood pressure (BP), an evidence-based review of studies evaluating these interventions may help to guide clinical practice.

METHODS

We employed systematic review and meta-analysis of the literature (1970-1999) to assess the independent and additive effects of three behavioral interventions on BP control (counseling, self-monitoring of BP, and structured training courses).

RESULTS

Of 232 articles assessing behavioral interventions, 15 (4072 subjects) evaluated the effectiveness of patient-centered counseling, patient self-monitoring of BP, and structured training courses. Pooled results revealed that counseling was favored over usual care (3.2 mmHg [95% CI, 1.2-5.3] improvement in diastolic blood pressure [DBP] and 11.1 mmHg [95% CI, 4.1-18.1] improvement in systolic blood pressure [SBP]) and training courses (10 mmHg improvement in DBP [95% CI, 4.8-15.6]). Counseling plus training was favored over counseling (4.7 mmHg improvement in SBP [95% CI, 1.2-8.2]) and afforded more subjects hypertension control (95% [95% CI, 87-99]) than those receiving counseling (51% [95% CI, 34-66]) or training alone (64% [95% CI, 48-77]).

CONCLUSIONS

Evidence suggests that counseling offers BP improvement over usual care, and that adding structured training courses to counseling may further improve BP. However, there is not enough evidence to conclude whether self-monitoring of BP or training courses alone offer consistent improvement in BP over counseling or usual care. The magnitude of BP reduction offered by counseling indicates this may be an important adjunct to pharmacologic therapy.

A computerized tool for evaluating the effectiveness of preventive interventions

In identifying appropriate strategies for effective use of preventive services for particular settings or populations, public health practitioners employ a systematic approach to evaluating the literature. Behavioral intervention studies that focus on prevention, however, pose special challenges for these traditional methods. Tools for synthesizing evidence on preventive interventions can improve public health practice. The authors developed a literature abstraction tool and a classification for preventive interventions. They incorporated the tool into a PC-based relational database and user-friendly evidence reporting system, then tested the system by reviewing behavioral interventions for hypertension management. They performed a structured literature search and reviewed 100 studies on behavioral interventions for hypertension management. They abstracted information using the abstraction tool and classified important elements of interventions for comparison across studies. The authors found that many studies in their pilot project did not report sufficient information to allow for complete evaluation, comparison across studies, or replication of the intervention. They propose that studies reporting on preventive interventions should (a) categorize interventions into discrete components; (b) report sufficient participant information; and (c) report characteristics such as intervention leaders, timing, and setting so that public health professionals can compare and select the most appropriate interventions.

Scope and organization of the Guide to Community Preventive Services. The Task Force on Community Preventive Services

BACKGROUND

The diverse nature of the target audience (i.e., public health decision-makers) for the Guide to Community Preventive Services: Systematic Reviews and Evidence-Based Recommendations (the Guide) dictates that it must be broad in scope. In addition, for the Guide to be most useful for its target audience, its organization and format must be carefully considered.

DETERMINING THE SCOPE OF THE GUIDE

Healthy People objectives and actual causes of death were used to determine the contents of the Guide. A priority setting exercise resulted in the selection of 15 topics for systematic reviews using the following criteria: burden of the problem, preventability, relationship to other public health initiatives, usefulness of the package of topics selected and level of current research and intervention activity in public and private sectors. Interventions within each topic target state and local levels and include population-based strategies, individual strategies in other than clinical settings and group strategies.

ORGANIZATION OF THE GUIDE

The Guide is organized into: Introduction, Reviews and Recommendations (three sections: Changing Risk Behaviors, Reducing Diseases, Injuries, or Impairments, and Addressing Environmental and Ecosystem Challenges), Appendixes, and Indexes.

DISCUSSION

The scope and organization of the Guide were determined using relevant public health criteria and expert opinion to provide a useful and accessible document to a broad target audience. While the final contents of the Guide may change during development, the working table of contents described in this paper provides a framework for development of the Guide and conveys its scope and intention.

Developing the Guide to Community Preventive Services--overview and rationale. The Task Force on Community Preventive Services

When the GUIDE TO COMMUNITY PREVENTIVE SERVICES: Systematic Reviews and Evidence-Based Recommendations (the Guide) is published in 2001, it will represent a significant national effort in encouraging evidence-based public health practice in defined populations (e.g., communities or members of specific managed care plans). The Guide will make recommendations regarding public health interventions to reduce illness, disability, premature death, and environmental hazards that impair community health and quality of life. The Guide is being developed under the guidance of the Task Force on Community Preventive Services (the Task Force)-a 15-member, nonfederal, independent panel of experts. Subject matter experts, methodologists, and scientific staff are supporting the Task Force in using explicit rules to conduct systematic literature reviews of evidence of effectiveness, economic efficiency, and feasibility on which to base recommendations for community action. Contributors to the Guide are building on the experience of others to confront methodologic challenges unique to the assessment of complex multicomponent intervention studies with nonexperimental or nonrandomized designs and diverse measures of outcome and effectiveness. Persons who plan, fund, and implement population-based services and policies to improve health at the state and local levels are invited to scrutinize the work in progress and to communicate with contributors. When the Guide is complete, readers are encouraged to consider critically the value and relevance of its contents, the implementation of interventions the Task Force recommends, the abandonment of interventions the Task Force does not recommend, and the need for rigorous evaluation of the benefits and harms of promising interventions of unknown effectiveness.

Poverty and ill health: physicians can, and should, make a difference

A growing body of research confirms the existence of a powerful connection between socioeconomic status and health. This research has implications for both clinical practice and public policy and deserves to be more widely understood by physicians. Absolute poverty, which implies a lack of resources deemed necessary for survival, is self-evidently associated with poor health, particularly in less developed countries. Over the past two decades, economic decline or stagnation has reduced the incomes of 1.6 billion people. Strong evidence now indicates that relative poverty, which is defined in relation to the average resources available in a society, is also a major determinant of health in industrialized countries. For example, persons in U.S. states with income distributions that are more equitable have longer life expectancies than persons in less egalitarian states. There are numerous possible approaches to improving the health of poor populations. The most essential task is to ensure the satisfaction of basic human needs: shelter, clean air, safe drinking water, and adequate nutrition. Other approaches include reducing barriers to the adoption of healthier modes of living and improving access to appropriate and effective health and social services. Physicians as clinicians, educators, research scientists, and advocates for policy change can contribute to all of these approaches. Physicians and other health professionals should understand poverty and its effects on health and should endeavor to influence policymakers nationally and internationally to reduce the burden of ill health that is a consequence of poverty.

The physician's perception of health care

A general malaise appears to have settled on the American medical scene; most Americans continue to trust their own physicians but do not trust the medical profession or the health system as a whole, while many physicians feel harassed by the regulatory, bureaucratic, or litigious intrusions upon the patient-doctor relationship. The strains on mutual trust among physicians, their patients, and the public are being played out against a background of contradictions. The advances of biomedicine are offset by the neglect of social and behavioural aspects of medical care. Preoccupation with specialized, hospital-based treatment is accompanied by isolation of public health and preventive interests from medical education and practice. Society remains uncertain whether health care is a right or a privilege while accepting public responsibility for financing the health care of certain groups such as the indigent sick (Medicaid), the elderly (Medicare), Native Americans, or members of the armed forces and veterans. Rising expectations about better outcomes through advances in technology are accompanied by rising anxieties about cost, appropriateness of care, access, and quality. Physicians must alter their perception of health care by adopting a population-based approach to need, a commitment to restoring equity in staffing patterns and compensation between primary care and specialty care, and adoption of a social contract that provides for full access by all Americans to basic cost-effective preventive and clinical services before spending on less cost-effective services.

Diffusion of the U.S. Preventive Services Task Force recommendations into practice

The U.S. Preventive Services Task Force's "Guide to Clinical Preventive Services" summarizes the results of a critical review of the literature pertaining to the effectiveness of 169 interventions in modifying 60 risk factors or conditions. The ultimate impact of the guide depends on the diffusion into clinical practice of its recommendations. This report reviews the factors influencing the diffusion process. Three categories of behavioral influence--predisposing, enabling, and reinforcing factors--apply to this diffusion process. Predisposing factors include knowledge and attitudes, personal health behaviors, confidence, and beliefs about patients' interests in health-promotion advice. Enabling factors include competence to perform preventive services, reimbursement for preventive services, organization of the practice setting, time to provide preventive services, a reminder system, and a coherent set of guidelines that are perceived as scientific and unambiguous. Reinforcing factors include peer support, feedback, evidence of results, and an enhanced sense of self-efficacy in fulfilling one's role as a healer. Recommendations are given for using these factors to increase the diffusion of preventive services into clinical practice.

Effectiveness of methods used to teach breast self-examination

The efficacy of breast self-examination (BSE) is limited by the extent to which women can be taught to perform a frequent and proficient examination. We randomized 783 women from a health maintenance organization into group instruction, individual instruction, individual instruction with a reminder system, or minimal intervention designed to simulate an office encounter where BSE was encouraged but not taught. The percentage of lumps 1 cm and smaller detected in silicone breast models, the number of false-positive detections, the search technique, and the self-reported BSE frequency were measured before and four months after intervention. Multiple tests for comparisons of interventions showed that the interventions containing BSE instruction were comparable in increasing true- and false-positive detection of lumps and in improving search technique, but the minimal intervention resulted in lower scores for all three outcomes (P less than .0001). Women in all four intervention groups increased their BSE frequency over the four-month follow-up period, but the greatest improvement in frequency was reported among women receiving reminders.

Inventory of knowledge and skills relating to disease prevention and health promotion

An inventory of the knowledge and skills appropriate for the instruction of medical students in the disciplines of disease prevention and health promotion was developed by a steering committee of medical practitioners and teachers, with the input of over 70 colleagues. The inventory, which is intended as a guide for curriculum planners, defines the fundamentals of subject areas appropriate for the general education of all physicians, including the skills and knowledge related to delivery of personal disease prevention/health promotion services, quantitative methods, health services organization and delivery, and community dimensions of medical practice, as well as attitudes and philosophy.

Dipstick urinalysis screening of asymptomatic adults for urinary tract disorders. I. Hematuria and proteinuria

We review evidence on the value of dipstick urinalysis screening for hemoglobin and protein in asymptomatic adults. In young adults, evidence from five population-based studies indicates that fewer than 2% of those with a positive heme dipstick have a serious and treatable urinary tract disease, too few to justify screening and the risks of subsequent workup. For older populations, evidence is contradictory and no recommendation can presently be made for or against hematuria screening. A population-based randomized, controlled trial of hematuria screening in the elderly is urgently needed. Proteinuria screening is not recommended in any healthy, asymptomatic adult population, since four population-based studies have found that fewer than 1.5% of those with positive dipsticks have serious and treatable urinary tract disorders.

Dipstick urinalysis screening of asymptomatic adults for urinary tract disorders. II. Bacteriuria

Using criteria adopted by the US Preventive Services Task Force, we evaluated use of the dipstick urinalysis to screen for bacteriuria. When the leukocyte esterase and nitrite dipstick tests are combined, the positive predictive value for detecting bacteriuria exceeded 12% in groups with a 5% or higher prevalence of bacteriuria: women who are pregnant, diabetic, or over 60 years of age and all institutionalized elderly. Conventional antimicrobial regimens for asymptomatic bacteriuria have proved efficacious only for pregnant women. We conclude that pregnant women should be screened for bacteriuria, but with the more sensitive urine culture, because treatment prevents serious fetal and maternal sequelae. Dipstick screening may be justified in women who are over 60 years of age or diabetic. The prevalence of bacteriuria in other groups is too low to justify screening.

Localized measurements of refractive turbulence using spatial filtering of scintillations

Remote measurements of refractive turbulence strength with high spatial resolution are demonstrated. The technique uses spatial and temporal filtering of scintillation from a spatially filtered incoherent optical source. Spatial resolution as fine as 4.5 m was observed at the center of a 110-m propagation path. An analytic approximation to the theory agrees very well with the data. This theory predicts the spatial resolution of a system of this type to be in the vicinity of the path length divided by the total number of cycles in the transmitter and receiver spatial filters.

Relation between age, education, and time to respond to questions in a computer-based medical interview

The time required for 458 women volunteers to respond to questions in a computer-based medical interview was related both to their age and to their formal education. When the analysis was restricted to the 220 women with a college degree, older women responded more slowly than their younger counterparts, and when the analysis was restricted to the 265 women between 18 and 30 years of age, women with less formal education took longer to respond. By contrast, the time required for the volunteers to record their responses was related only to age.

The chorioallantoic membrane in irritation testing

The chorioallantoic membrane (CAM) of the chick embryo is a fusion membrane with a blood vessel complex. It was examined as a possible means of predicting the irritant potential of chemicals for the conjunctiva, as observed in the Draize eye test. Nine chemicals of known irritancy potential for the eye in vivo were selected from published data, and each was tested at four different concentrations. The treated CAMs were examined macroscopically at 4, 24 and 48 hr after treatment, and were then prepared for histological examination. A dose response was observed for each chemical. In only four of the nine chemicals could the response in the CAM be considered to predict the in vivo activity. In another two, the correlation was poor. Three chemicals, glycerine, polyethylene glycol and Tween 80, all reported to be harmless to the eye, were embryotoxic at more than one concentration. Histological changes were degeneration or necrosis at the treated site without the chemical features of heterophil (chicken neutrophil) infiltration or significant macrophage infiltration. It is concluded that the CAM is not a suitable tissue for predicting in vivo irritant potential of substances for the conjunctiva, and that it provides no more information than could be obtained from cell cultures.

Comparing ambulatory care practices of primary care and traditional medicine residents

Although special residency programs preparing internists for primary care have been in existence for a decade, little is known about whether these tracks have achieved their goals. As part of a multicenter evaluation of ambulatory care at four university hospitals, 1,040 patient care encounters were reviewed for 16 primary-care and 41 traditional medicine residents. Using a chart-based audit, the authors examined 16 discrete items of patient care to assess resident management in the following areas: screening for colorectal carcinoma, management of hypertension, benzodiazepine drug prescribing, and management of chronic lung disease. Their hypothesis that primary care residents would score higher than traditional medicine residents in the areas of screening, prevention, and prescribing of drugs was not supported. There was no association between type of training and performance of a task with the following exception: second-year primary care residents screened for colorectal carcinoma in 86% (126) of patients whose charts were audited, while second-year traditional medicine residents did so in 77% (160) (P less than 0.025). This difference was not maintained when the residents were reaudited 1 year later. Both groups of residents scored high in all areas with the following exceptions: documentation of the amount of sedative dispensed and immunization of susceptible patients against pneumococcus and influenza. The ambulatory practices of both groups of residents exceeded expectations, probably because of the wider influence of primary care training.

Health-promoting behavior among lawyers and judges

This report compares the health-promoting behaviors of lawyers and judges and contrasts these behaviors with published data from nationwide surveys of the general population. Data were obtained from a self-administered questionnaire distributed to a random sample of Massachusetts lawyers and a group of judges attending an annual meeting of midwestern state municipal judges. Compared to the United States general population, lawyers and judges have more favorable health-promoting practices with respect to smoking, exercise, and use of seatbelts but are similar in terms of drinking habits and drinking problems, diet and weight consciousness, and the prevalence of tension, stress or pressure from their work.

Profile of women practicing breast self-examination

The monthly practice of breast self-examination (BSE) can result in the early diagnosis of breast cancer. To explore factors that influence women's habits in the practice of BSE, we interviewed 616 women using an interactive computer program. We found that these women were more likely to practice BSE on a frequent basis if they were living with their sexual partner, had been shown how to perform BSE, and were confident in their examination technique. Women with a maternal history of breast disease were also more likely to practice monthly BSE. Unlike past reports that women with formal education beyond high school practice BSE more frequently than less-educated women, our study showed no association between monthly BSE practice and formal education. Contrary to our hypothesis that BSE practice was associated with the practice of other preventive health activities, our study did not demonstrate such a relationship. These findings suggest that demonstrating BSE at the periodic health examination may help increase the number of women practicing BSE on a frequent basis.

Wind measurements by the temporal cross-correlation of the optical scintillations

Various methods of correlation analysis that have been used to deduce crosswind from a drifting scintillation pattern are briefly described and then compared with regard to their immunity to noise and their accuracy when faced with nonuniformities along the propagation path or changes in the characteristics of the turbulence. Of the techniques considered, none is ideal; but a new technique, using complete knowledge of the cross-covariance function, proves to be advantageous in a wide variety of situations.

Histopathologic observations after short-term implantation of two porous elastomers in dogs

This report describes the effects of pore size and material on soft tissue ingrowth of two medical-grade elastomers. Using the replamineform process, silicone rubber (SR) and bioelectric polyurethane (BEP) were rendered microporous with essentially the same microstructural pore configuration. Implants were prepared in each material having five pore size ranges: 18-25 microns, 30-45 microns, 75-95 microns, 60-120 microns, and 120-180 microns. Implants 1 cm X 1 cm X 1 mm were harvested at 1, 2, 4 and 12 weeks following subcutaneous implantation in mongrel dogs. Ingrowth of the 18-25 microns and 30-45 microns implants in both polymers consisted of histiocytes and dispersed fibrocytic proliferation during the first two weeks. By 12 weeks, the fibrocytic component had increased, but histiocytes remained the principal component of ingrown tissue. In contrast, initial ingrowth of the 75-95 microns, 60-120 microns and 120-180 microns implants showed increased fibrocytic proliferation and minimal histiocytic reaction. By 12 weeks, ingrowth into the larger-pore implants had progressed to broad bands of well organized collagenous stroma. Differences in the rate of tissue ingrowth were found to be related to both material and pore size. Less than 15% of the void spaces were infiltrated by 4 weeks in 18-25 microns and 30-45 microns SR implants, although this increased to approximately 50% by 12 weeks. In contrast, the 3 larger-pore SR implants and all pore sizes in the BEP implants were almost completely ingrown by 4 weeks.

Optical rain gauge using a divergent beam

We have shown that path-averaged rain rates can be obtained from the raindrop-induced amplitude scintillations of a divergent laser beam (spherical wave case). We found that the rain rate obtained from a divergent beam is less sensitive to drop-size distribution than that from a collimated beam. However, the path-weighting function is heavily weighted toward the receiving end in the spherical wave case, whereas in the plane wave case, it is almost uniformly weighted along the optical path. The theory was confirmed by observations on two optical paths, one using a collimated beam on a 200-m path, the other using a divergent beam on a 1000-m path. The results for the longer path show a saturation effect for rain rates higher than 12 mm/h.

Where have all the doctors gone? Physician choices between specialty and primary care practice

Public concern about physician manpower is becoming increasingly focused on the distribution of physicians across specialties. Although an optimal mix of physicians has not been clearly defined, most interested parties agree that more primary care doctors are needed. We examine economic, psychological, and organizational incentives that tend to induce physicians to pursue careers in subspecialties rather than primary care. The existing incentive structure needs to be examined more closely and will almost certainly have to be redesigned if efforts to redeploy physician manpower are to be successful.