McLaren Health Care

This paper presents a computational technique for the prediction of fatigue-driven delamination growth in composite materials. The interface element, which has been extensively applied to predict delamination growth due to static loading, has been modified to incorporate the effects of cyclic loading. Using a damage mechanics formulation, the constitutive law for the interface element has been extended by incorporating a modified version of a continuum fatigue damage model. The paper presents details of the fatigue degradation strategy and examples of the predicted fatigue delamination growth in mode I, mode II and mixed mode I/II are presented to demonstrate that the numerical model mimics the Paris law behaviour usually observed in experimental testing. Copyright © 2005 John Wiley & Sons, Ltd.

BACKGROUND: Blunt thoracic aortic injury, a life-threatening concern, remains the second most common cause of mortality among all non-penetrating traumatic injuries, second only to intracranial hemorrhage. Kinetic forces from the rapid deceleration are the impetus for the injury mechanism and are graded accordingly. Given the prevalence of trauma as a public health problem, contemporary management considerations are important. MAIN BODY: Blunt thoracic aortic injury may be fatal if not diagnosed and treated expeditiously. Endovascular options allow safe and effective management of these dangerous injuries. This paper describes the overview of blunt thoracic aortic trauma, the epidemiology, presentation, diagnosis, and treatment options with a focus on endovascular management. CONCLUSION: Blunt thoracic aortic injury requires a high index of suspicion based on mechanism of injury in the trauma population. Endovascular options have become the mainstay of blunt thoracic aortic injury treatment whenever feasible with satisfactory results and long-term outcomes.

BACKGROUND: Recruitment plays a vital role in conducting randomized control trials (RCTs). Challenges and failure of proper recruitment lead to early termination of trials. Monetary incentives have been suggested as a potential solution to these challenges. Therefore, we aimed to do a systematic review and analysis to evaluate the effect of incentives on the number of participants willing to consent to and participate in RCTs. METHODS: Electronic databases were systematically searched from inception to September 23rd, 2021, using the following keywords: payments, incentive, response, participation, enrollment, randomized, randomization, and RCT. The Cochrane Risk of Bias tool was used to assess the quality of the included trials. Risk ratios (RRs) were calculated with their corresponding 95% confidence interval (CI). All analyses were done with the random-effects model. We used Revman software to perform the analysis. RESULTS: Six RCTs with 6,253 Participants met the inclusion criteria. Our analysis showed significant improvement in response rate (RR: 1.27; 95% CI: 1.04, 1.55; P = 0.02) and consent rates (RR: 1.44; 95% CI: 1.11, 1.85; P = 0.006) when an incentive payment was offered to participants. Even a small amount of incentive showed significant improvement in both consent (RR: 1.33; 95% CI: 1.03, 1.73; P = 0.03) and response rates (RR: 1.26; 95% CI: 1.08, 1.47; P = 0.004). CONCLUSION: In conclusion, our meta-analysis demonstrated statistically significant increases in the rate of consent and responses from participants when offered even small monetary value incentives. These findings suggest that incentives may be used to reduce the rate of recruitment failure and subsequent study termination. However, further RCTs are needed to establish a critical threshold beyond which incentive amount does not alter response rates further and the types of RCTs in which financial incentives are likely to be effective.

OBJECTIVE: To delineate the specific practices that physicians use to promote their own well-being. DESIGN, SETTING, AND PARTICIPANTS: 304 members of a primary care practice-based research group responded by mail to a survey on physician well-being. From the original survey, 130 subjects responded to an open-ended survey item regarding their own wellness-promotion practices. METHODS: Qualitative content analysis was used to identify the common themes in the physicians' responses to the open-ended question. A validated 18-item instrument, the Scales of Psychological Well-Being (SPWB), was used for measurement. MAIN OUTCOME MEASURES: Similarities and differences between the various wellness-promotion practices that respondents reported using and associations between the use of these practices and SPWB scores. RESULTS: The 5 primary wellness-promotion practices that evolved from thematic analysis of the survey responses included "relationships," "religion or spirituality," "self-care," "work," and "approaches to life." The use of the last type of practice was significantly associated with increased psychological well-being (SPWB) scores compared with the use of any of the other wellness-promotion practice categories (P<0.01), and there was a trend toward increased well-being among users of any category of wellness-promotion practices. Comments by our respondents provide specific descriptions of how physicians attend to their emotional, spiritual, and psychological well-being. CONCLUSION: Physicians use a variety of approaches to promote their own well-being, which sort themselves into 5 main categories and appear to correlate with improved levels of psychological well-being among users.

The Pliofilm cohort is the most intensely studied group of workers chronically exposed to benzene. Information on this cohort has been the basis for regulations and/or guidelines for occupational and environmental exposure to benzene. Rinsky et al. (1986, 1987) and Crump and Allen (1984) developed different approaches for reconstructing the exposure history of each member of the group. The predicted levels of exposure, combined with the data on the incidence of disease, have been used to estimate benzene's carcinogenic potency. In this paper, recent information from worker interviews and historical records from the National Archives and elsewhere were used to evaluate the accuracy of prior exposure estimates and to develop better ones for the cohort. The following factors were accounted for: (1) uptake of benzene due to short-term, high-level exposure to vapors, (2) uptake due to background concentrations in the manufacturing building, (3) uptake due to contact with the skin, (4) morbidity and mortality data on workers in the Pliofilm process, (5) the installation of industrial hygiene engineering controls, (6) extraordinarily long work weeks during the 1940s, (7) data indicating that airborne concentrations of benzene were underestimated due to inaccurate monitoring devices and the lack of adequate field calibration mated due to inaccurate monitoring devices and the lack of adequate field calibration of these devices, and (8) likely effectiveness of respirators and gloves. Our estimates suggest that Crump and Allen (1984) overestimated the exposure of workers in some job classifications and underestimated others, and that Rinsky et al. (1981, 1986) almost certainly underestimated the exposure of nearly all workers. Airborne concentrations of benzene at the St. Marys facility during the years of its operation were found (on average) to be about half those of the two Akron facilities. Our analysis indicates that short-term, high-level exposure to benzene vapors and dermal exposure significantly increased (by about 25-50%) the total absorbed dose of benzene for some workers. One of the key findings was that, unlike prior analyses, the three facilities probably had significantly different airborne concentrations of benzene, especially during the 1940s and 1950s.

Monkeypox is a rare viral infection, endemic in many central and western African countries. The last international outbreak of monkeypox reported outside Africa occurred back in 2003. However, monkeypox has reemerged at a global scale with numerous confirmed cases across the globe in 2022. The rapid spread of cases through different countries has raised serious concerns among public health officials worldwide prompting accelerated investigations aimed to identify the origins and cause of the rapid expansion of cases. The current situation is reminiscent of the very early stages of the still ongoing COVID-19 pandemic. Overlapping features between these, two seemingly alike viral entities include the possibility for airborne transmission and the currently unexplained and rapid spread across borders. Early recognition of cases and timely intervention of potential transmission chains are necessary to contain further outbreaks. Measures should include rapid and accurate diagnosis of cases meeting case definitions, active surveillance efforts, and appropriate containment of confirmed cases. Governments and health policymakers must apply lessons learned from previous outbreaks and start taking active steps toward limiting the recent global spread of monkeypox. Herein, we discuss the status of the current monkeypox outbreaks worldwide, the epidemiological and public health situation at a global scale and what can be done to keep at bay its further expansion and future global implications.

Millions of tons of chromite-ore processing residue have been used as fill in various locations in northern New Jersey and elsewhere in the United States. The primary toxicants in the residue are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is a human carcinogen following inhalation of high concentrations. It can also cause allergic contact dermatitis. This evaluation addresses a residential site where the arithmetic mean (x) and geometric mean (gm) concentrations of Cr(III) in soil were 2879 and 1212 mg/kg (ppm). The mean and geometric mean concentrations of Cr(VI) were 180 and 4 mg/kg, respectively. The uptake (absorbed dose) of Cr(III) via soil ingestion, consumption of homegrown vegetables, and ingestion of inspired particles was determined. The uptake of Cr(VI) via dermal absorption from contact with surface soil and building wall surfaces, as well as inhalation, was also evaluated. The techniques used in this assessment are applicable for evaluating the human health risks posed by any residential site having contaminated soil. The potential for both sensitized and unsensitized persons to develop allergic contact dermatitis due to exposure to soil contaminated at these levels was found to be negligible. The estimated average daily dose (ADD) via ingestion and dermal absorption for the maximally exposed individual (MEI) was about 1500- and 40-fold below the EPA reference dose (RfD) for Cr(III) and Cr(VI), respectively. It was shown that for residential sites, the most important route of exposure to Cr(III) was incidental soil ingestion. Although not relevant to these sites specifically, if garden vegetables could be successfully grown in these soils, then they would probably be the predominant source of uptake of Cr(III). Since inhalation of Cr(VI)-contaminated dust (but not ingestion or dermal contact) poses a cancer hazard, the doses and associated risks were assessed. The estimated cancer risks for the MEI and most likely exposed individual (MLEI) were approximately 5 x 10(-9) and 2 x 10(-9), respectively. These levels of risk have always been considered well below those that warrant regulatory concern. For persons living on residential properties, the cancer risk due to inhaling suspended particles is likely to be less than 1 in 1,000,000 if Cr(VI) levels in soil are less than 180 mg/kg (ppm). Based on this analysis, the levels of Cr(III) and Cr(VI) at this and similar sites do not pose a health hazard following acute or chronic exposure.

The health risks posed by soil pollutants are generally thought to be due to soilingestion and have often resulted in massive regulatory efforts to remedy such contamination. The contribution of this route to the actual human health hazard has been questioned, however, as soil removal alone seems to have little influence on the body burdens of soil contaminants in exposed individuals. Ongoing research also has repeatedly and substantially reduced the estimates of soilingested daily. Because comparatively little time is spent outdoors by most individuals, exposure to soil brought indoors, present as house dust, is now thought to be nearly as important as the directingestion of soil. Exposure via house dust has not been studied specifically, but several observations suggest that it may be important. Dust is largely composed of fine particles of tracked-in soil. The smaller dust particles cling to surfaces better than soil, and contaminant concentrations are often higher in house dust. Fine particles are likely to be more bioavailable, and degradation is slower indoors. Contaminants thus may be concentrated and more readily available in the areas most frequented. In some studies, contaminant levels in dust are correlated more closely with body burdens of contaminants than other sources, suggesting that this route should be considered when assessing risks from soil. Until more research addressing exposure to dust is conducted, recommendations for assessing potential health risks from this pathway are provided.

This set of studies was designed to examine the relational underpinnings of child abuse potential in a sample of 51 urban families. In Study 1, lower maternal differentiation of self-most notably, greater emotional reactivity and greater emotional cutoff-along with self-attacking introjects, together distinguished mothers at higher risk (vs. lower risk) for child maltreatment (CM). In Study 2, patterns of interactive rupture and repair were examined in a subsample of n = 15 families and found to vary as a function of risk for CM. Specifically, SASB coding (Benjamin, 1996, 2003) of mother-children interactions during two moderately stressful lab tasks revealed higher rates of interactive mismatch and mother-initiated ruptures, and fewer successful repairs in families at higher-risk-for-CM, relative to families at lower-risk. Implications for counseling and directions for further translational research are discussed.

BACKGROUND: Surveys are an effective method for collecting a large quantity of data. However, incomplete responses to these surveys can affect the validity of the studies and introduce bias. Recent studies have suggested that monetary incentives may increase survey response rates. We intended to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of monetary incentives on survey participation. METHODS: A systematic search of electronic databases was conducted to collect studies assessing the impact of monetary incentives on survey participation. The primary outcome of interest was the response rates to incentives: money, lottery, and voucher. We used the Cochrane Collaboration tool to assess the risk of bias in randomized trials. We calculated the rate ratio (RR) with its 95% confidence interval (95% CI) using Review Manager Software (version 5.3). We used random-effects analysis and considered the data statistically significant with a P-value <0.05. RESULTS: Forty-six RCTs were included. A total of 109,648 participants from 14 countries were involved. The mean age of participants ranged from 15 to more than 60 years, with 27.5% being males, 16.7% being females, and the other 55.8% not reported. Our analysis showed a significant increase in response rate in the incentive group compared to the control group, irrespective of the incentive methods. Money was the most efficient way to increase the response rate (RR: 1.25; 95% CI: 1.16,1.35; P = < 0.00001) compared to voucher (RR: 1.19; 95% CI: 1.08,1.31; P = < 0.0005) and lottery (RR: 1.12; 95% CI: 1.03,1.22; P = < 0.009). CONCLUSION: Monetary incentives encourage the response rate in surveys. Money was more effective than vouchers or lotteries. Therefore, researchers may include money as an incentive to improve the response rate while conducting surveys.

In 1992, a simple and sensitive assay for detecting DNA-protein crosslinks was developed [1]. In an effort to facilitate the greater use of the assay, a number of studies were conducted to evaluate its reliability and reproducibility. During this work, the assay was used to assess whether various metals and other compounds could induce crosslinks in cultured human lymphocytes (Epstein-Barr virus-transformed Burkitt's Lymphoma cell line). Potassium permanganate, mercury chloride, lead nitrate, magnesium perchlorate, aluminum chloride, and cadmium chloride did not induce DNA-protein crosslinks at either cytotoxic or non-cytotoxic levels. Copper sulfate, arsenic trioxide, and potassium chromate induced DNA-protein crosslinks only at cytotoxic concentrations. Acute lethality of the cells was assessed immediately after exposure to metals by trypan blue exclusion while long-term lethality was assessed by cell proliferation and trypan blue exclusion following an incubation period of 5 days after exposure to the metal compound. All metals exhibited more toxicity in the long-term lethality assay compared to the short-term assay. The cultured human lymphocytes treated with various doses of lead acetate, cadmium chloride, arsenic trioxide and copper sulfate, as well as cis-platinum and chromate, were sent to four different laboratories to compare the reliability and reproducibility of the DNA-protein crosslink assay. Depending on the chemical studied, there were quantitative differences in the results observed among the various laboratories using the assay. However, all laboratories generally showed that cis-platinum, chromate, arsenic trioxide and copper sulfate induced DNA-protein crosslinks at levels that produced acute cytotoxicity, whereas cadmium chloride and lead acetate did not.

Common causes of hyperpigmentation include postinflammatory hyperpigmentation, melasma, solar lentigines, ephelides (freckles), and café-au-lait macules. Although most hyperpigmented lesions are benign and the diagnosis is straightforward, it is important to exclude melanoma and its precursors and to identify skin manifestations of systemic disease. Treatment options for postinflammatory hyperpigmentation, melasma, solar lentigines, and ephelides include the use of topical agents, chemical peels, cryotherapy, or laser therapy. Caf&-au-lait macules are amenable to surgical excision or laser treatment. Disorders of hypopigmentation may also pose diagnostic challenges, although those associated with health risks are uncommon and are usually congenital (e.g., albinism, piebaldism, tuberous sclerosis, hypomelanosis of Ito). Acquired disorders may include vitiligo, pityriasis alba, tinea versicolor, and postinflammatory hypopigmentation. Treatment of patients with widespread or generalized vitiligo may include cosmetic coverage, psoralen ultraviolet A-range therapy (with or without psoralens), or narrow-band ultraviolet-B therapy; whereas those with stable, limited disease may be candidates for surgical grafting techniques. Patients with extensive disease may be candidates for depigmentation therapy. Other acquired disorders may improve or resolve with treatment of the underlying condition.

Nursing home-associated infections and antibiotic resistant pathogens constitute common and serious problems in the geriatric population.Chryseobacterium indologenes, a non-motile Gram-negative rod, though widely distributed in nature, is an uncommon human pathogen. Typically thought of as an organism of low virulence, it may cause serious infections, particularly among the immunocompromised. The majority of reported cases are nosocomial, often associated with immunosuppression or indwelling catheters. It has been reported as the causative agent in bacteraemia, peritonitis, pneumonia, empyema, pyelonephritis, cystitis, meningitis and central venous catheter-associated infections. We report a rare case of C. indologenesinfection affecting a nursing home resident in the USA and we provide a review of similar cases. This report emphasises the importance of individualised treatment and promotes awareness about this organism as one of several emerging pathogens in immunocompromised adults and in the frail elderly who are often nursing home residents, in the Western Hemisphere.

Dental caries is the most prevalent infectious disease among US children. National surveys have shown that poor and minority-group children are not only disproportionately affected by dental caries but also have limited access to oral health care. Following successful exploratory applications of both synchronous and asynchronous models at the Eastman Institute for Oral Health, teledentistry has been demonstrated to be a practical and cost-effective way to improve oral health care for rural and disadvantaged children. These models support the role of teledentistry in reducing the costs of and barriers to accessing oral health care, improving oral health outcomes, increasing use of oral health care resources, and leading to the establishment of a dental home for underserved children. The advancement of teledentistry underscores the need for its integration with local, regional, and national telehealth programs and the role of policy makers in establishing a balanced framework for teledentistry within the overarching health care system.

Objective To systematically review the scoring systems used to report findings during drug-induced sleep endoscopy (DISE) for adults and children with obstructive sleep apnea. Data Sources PubMed, CINAHL, EBM Reviews, Embase, and Scopus databases. Review Methods This is a systematic review of all indexed years of publications referring to scoring of DISE for children and adults with obstructive sleep apnea. The type of DISE scoring system utilized was the primary outcome. PRISMA guidelines were followed to carry out this review; articles were independently reviewed by 2 investigators. All pediatric and adult studies that utilized ≥1 DISE grading systems were included. Results Of 492 identified abstracts, 44 articles (combined population, N = 5784) were ultimately included; 6 reported on children, 35 on adults, and 1 on children and adults. Twenty-one reporting methods were used in these studies, with the most common being the VOTE system (velum, oropharynx, tongue base, and epiglottis; 38.6%) and the Pringle and Croft classification (15.9%). The sites of obstruction most commonly included in a scoring system were the tongue base (62%), lateral pharynx/oropharynx (57%), palate (57%), epiglottis/supraglottis (38%), and hypopharynx (38%). Less commonly included sites were the larynx (29%), velum (23%), nose (23%), tongue (14%), adenoids (10%), and nasopharynx (10%). Conclusion There is no consensus regarding which scoring system should be utilized to report findings during DISE. The VOTE system and the Pringle and Croft classification were the most frequent scoring systems reported for patients undergoing DISE. Standardization of the reporting of DISE findings would improve comparability among studies.

Millions of tons of chromite-ore processing residue have been used as fill in various locations in Northern New Jersey and elsewhere in the United States. The primary toxicants in the residue are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is considered a inhalation human carcinogen at high concentrations. Approximately 40 commercial and industrial properties in Northern New Jersey have been identified as containing chromite ore processing residue in the soil. One site, a partially-paved trucking terminal, was evaluated in this assessment. The arithmetic mean and geometric mean concentrations of total chromium in soil were 977 and 359 mg/kg, respectively. The data were log-normal distributed. The arithmetic mean and geometric mean concentrations of Cr(VI) in surface soil were 37.6 and 3.1 mg/kg, respectively. The data could not be fit to a standard distribution, likely due to the large number of samples with concentrations below the method detection limit (65%). Dose was calculated for each exposure route using a Monte Carlo statistical simulation. Probability distributions of most exposure parameters were incorporated into the analyses to predict the range and probability of uptake for persons in the exposed population. The exposure parameter distributions included in this assessment are: the concentrations of Cr(VI) and total chromium in air and soil, fraction of the year when suspension of airborne soil particulates is likely to occur due to weather conditions, fraction of Cr(VI) in air which is respirable (less than 10 microns), soil loading rate on skin, occupational tenure, and body weight. The techniques used in this assessment are applicable for evaluating the human health risks posed by most industrial sites having contaminated soil. The estimated average daily dose (ADD) via ingestion and dermal absorption for the individual exposed at the 95th percentile was about 48,000- and 91-fold below the U.S. EPA reference dose (RfD) for Cr(III) and Cr(VI), respectively. Since inhalation of Cr(VI) contaminated dust (but not ingestion or dermal contact) poses a cancer hazard, the lifetime average daily doses (LADDs) associated with exposure at the 50th and 95th percentile were calculated to be 9.8 x 10(-8) and 1.3 x 10(-6), respectively. Based on this analysis, industrial sites having soil concentrations of Cr(VI) below 230 ppm do not pose a significant noncarcinogenic or carcinogenic health hazard following acute or chronic exposure. These risks would be even smaller if the sites were paved.

Through the process of glycolysis, one molecule of glucose breaks down to form two molecules of pyruvate. Depending on the microcellular environment (specifically, oxygen availability, energy demand, and the presence or absence of mitochondria), pyruvate has several separate fates:In mitochondria-containing cells, pyruvate can enter the citric acid cycle within the mitochondrial matrix and undergo oxidative phosphorylation. Aptly named due to its dependence on oxygen as the final electron acceptor, oxidative phosphorylation cannot take place in the absence of oxygen. Moreover, as the enzymes of both the citric acid cycle and electron transport chain are within the mitochondria, cells lacking mitochondria (e.g., erythrocytes) cannot rely on oxidative phosphorylation for energy production.In erythrocytes and oxygen-deprived tissue, pyruvate remains within the cytoplasm and converts to lactate, a process referred to as anaerobic glycolysis. This final reaction allows for the regeneration of NAD+, a cofactor that must be available in high enough intracellular concentrations for the earlier reactions of glycolysis to remain favorable. Compared to oxidative phosphorylation, however, anaerobic glycolysis is significantly less efficient, providing a net production of only 2 ATP per glucose molecule (versus 32 ATP per glucose molecule produced during oxidative phosphorylation).

The current literature shows increasing concerns about potential seminal transmission of monkeypox virus (MPXV). Accordingly, we aimed to understand better the potential presence of MPXV in the seminal fluids and others specimens obtained from MPX cases. On June 26, 2022, a systematic search of the literature was conducted to find articles that examine the presence of MPXV in the seminal fluid of confirmed cases. The search was updated once on August 12 and another on October 12, 2022, to include newly published articles. The prevalence of MPXV DNA presence in the seminal fluid and other specimens was pooled in a meta-analysis (from studies with sample size > 5 to reduce overestimation) and results were presented as effect sizes (ES) and their corresponding 95% confidence intervals (CI). Nine articles were included. Only five studies were eligible for a meta-analysis, and the pooled prevalence of MPXV DNA in semen specimens was 72.4% (95% CI: 55.7%-84.5%) among 115 patients. The positive rate of MPXV viral polymerase chain reaction (PCR) was higher among skin samples (89%; 95% CI: 78.2%-94.8%; N = 62; studies = 2), followed by anogenital/rectal samples (74.3%; 95% CI: 60.4%-84.5%; N = 54; studies = 2). On the other hand, the positivity rate was lower in nasopharyngeal (62.4%; 95% CI: 20.4%-91.5%; N = 587; studies = 3), urine (21.1%; 95% CI: 4.3%-61.1%; N = 617; studies = 4), and blood/plasma (14.3%; 95% CI: 11.3%-18.1%; N = 609; studies = 3) samples. Besides, MPXV can be detected in semen early from Day 1 and up to 19 days after symptoms onset. Finally, two articles investigated the infectivity of MPXV particles detected in seminal specimens by testing their replication competence. Culturing MPXV was successful in two out of four patients included in these studies. MPXV is highly prevalent in seminal specimens of MPX cases, further corroborating the role of sexual transmission of the disease. However, further evidence is still needed to shed more light on the replication competence of these particles.

PURPOSE: Current numbers of breast-feeding mothers are well below Healthy People 2010 goals of 75% in the early postpartum period, 50% at 6 months, and 25% at 1 year. A promising line of research is the use of an ecological model for breastfeeding that includes factors traditionally examined in breastfeeding (mother/infant and family) as well as mesosystem and exosystem sources of influence on families (healthcare delivery system, community, and societal/cultural). STUDY DESIGN AND METHODS: A telephone survey was conducted with 95 primiparous, postpartum women using closed and open-ended items. Content analysis was used with the transcribed comments from these telephone interviews, to test the fit of a preexisting ecological model for breastfeeding. RESULTS: The comments of postpartum women provided a rich source of information about the many mother-infant, family, healthcare delivery system, community, and societal/cultural factors that influence breastfeeding. These all fit the ecological breast-feeding model proposed. CLINICAL IMPLICATIONS: Efforts to improve rates of breastfeeding in this country to meet year 2010 goals must consider the many contextual factors that influence feeding. Interventions to promote breastfeeding should exceed the individual level, and occur at many layers simultaneously. The ecological model provides direction for the multiple interventions needed to increase rates and duration of breastfeeding.

Increased DNA-protein cross-linking (DPX) in circulating leukocytes has been proposed as a potential biomarker for exposure and genotoxic damage caused by inhalation of certain reactive chemicals, such as hexavalent chromium [Cr(VI)]. This study was designed to determine whether ingestion of a single dose of potassium dichromate alone [Cr(VI)] or potassium dichromate fully reduced to Cr(III) with orange juice (prior to ingestion) causes an increase in DPX of circulating leukocytes in humans. Four adult male volunteers ingested a bolus dose of 5000 micro chromium in a 0.51 volume of water (10 p.p.m.), and blood samples were collected at 0, 60, 120, 180 and 240 min afterwards for analysis of DPX formation in circulating leukocytes. Results were compared to each person's own background concentration of DPX in leukocytes. Blood and urine samples were also collected for up to 2 weeks following the dose to examine the pattern of uptake and excretion of chromium. The results showed that there was no significant change in DPX observed following either Cr(VI) or Cr(III) ingestion, even though blood and urine chromium measurements indicated systemic uptake of a substantial fraction of the ingested chromium. Since Cr(III) does not possess DPX-inducing properties while Cr(VI) does, these results suggest that the Cr(VI) was reduced to Cr(III) intragastrically prior to absorption or that the amount of Cr(VI) absorbed into the blood was insufficient to produce DPX. These results are consistent with prior research that indicated that DPX would not occur following exposure to Cr(VI) except at very high doses.