Biomedical subjects

David R Williams

Publications and source records attributed to David R Williams.

At least 91 records · Page 5Linked to original sources

PubMed2003

The integral role of pastoral counseling by African-American clergy in community mental health.

OBJECTIVE: Little is currently known about the pastoral counseling work of pastors of African-American churches. The authors interviewed the pastors of nearly all African-American churches in a metropolitan area about their pastoral counseling work and related aspects of their ministry. METHODS: Of 121 African-American pastors identified, 99 completed a semistructured interview describing their backgrounds, attitudes, concerns, and work. The interview included detailed queries about how they understood and carried out any pastoral counseling work. RESULTS: The respondents averaged more than six hours of counseling work weekly and often addressed serious problems similar to those seen by secular mental health professionals, with whom they reported readily exchanging referrals. Many of the respondents reported having and maintaining specialized education for their counseling work, which they described as including both spiritual and psychological dimensions. Most of the pastors reported that they observe and address severe mental illness and substance abuse in their congregations and that they also counsel individuals outside their own denominations. CONCLUSIONS: African-American urban ministers functioning as pastoral counselors constitute an engaging and useful group with experiences and skills that can be tapped by interested secular professionals. Their work represents a significant mental health resource for persons who lack sufficient access to needed care.

Adult↗

PubMed2003

Racial/ethnic discrimination and health: findings from community studies.

The authors review the available empirical evidence from population-based studies of the association between perceptions of racial/ethnic discrimination and health. This research indicates that discrimination is associated with multiple indicators of poorer physical and, especially, mental health status. However, the extant research does not adequately address whether and how exposure to discrimination leads to increased risk of disease. Gaps in the literature include limitations linked to measurement of discrimination, research designs, and inattention to the way in which the association between discrimination and health unfolds over the life course. Research on stress points to important directions for the future assessment of discrimination and the testing of the underlying processes and mechanisms by which discrimination can lead to changes in health.

Ethnicity↗

PubMed2003

The health of men: structured inequalities and opportunities.

I have summarized in this article data on the magnitude of health challenges faced by men in the United States. Across a broad range of indicators, men report poorer health than women. Although men in all socioeconomic groups are doing poorly in terms of health, some especially high-risk groups include men of low socioeconomic status (SES) of all racial/ethnic backgrounds, low-SES minority men, and middle-class Black men. Multiple factors contribute to the elevated health risks of men. These include economic marginality, adverse working conditions, and gendered coping responses to stress, each of which can lead to high levels of substance use, other health-damaging behaviors, and an aversion to health-protective behaviors. The forces that adversely affect men's health are interrelated, unfold over the life course, and are amenable to change.

Adaptation, Psychological↗

PubMed2003

Race, health, and health care.

Explore the source record for details and available documents.

Black or African American↗

PubMed2002

Color perception is mediated by a plastic neural mechanism that is adjustable in adults.

An intensely debated issue concerning visual-experience-dependent neural plasticity is whether experience is required only to maintain function or whether information from experience is used actively, relieving the necessity to hard-wire all connections and allowing adaptive adjustments. Here, an active role for experience is demonstrated in circuits for color vision. Chromatic experience was altered using colored filters. Over days there was a shift in color perception, as measured by the wavelength of unique yellow, which persisted 1-2 weeks after the filters were discontinued. Moreover, color-deficient adults were shown to have altered weightings of inputs to chromatic channels, demonstrating a large neural adjustment to their inherited photopigment defect. Thus, a neural normalization mechanism for color perception, determined by visual experience, operates to compensate for large genetic differences in retinal architecture and for changes in chromatic environment.

Adaptation, Physiological↗

PubMed2002

Religious involvement and cigarette smoking in young adults: the CARDIA study (Coronary Artery Risk Development in Young Adults)study (.

BACKGROUND: Results of previous studies have suggested that involvement in religious activities may be associated with lower rates of smoking. We sought to determine whether frequent attendance at religious services is associated with less smoking among young adults. METHODS: This prospective cohort study of 4569 adults aged 20 to 32 years included approximately equal numbers of blacks and whites and men and women from 4 cities in the United States who attended the 1987/1988 examination of the Coronary Artery Risk Development in Young Adults (CARDIA) study. Frequency of attendance at religious services and denominational affiliation were determined by self-report questionnaire in 1987/1988. Cigarette smoking was determined by interview at this time and again 3 years later. RESULTS: Of 4544 participants who completed the tobacco questionnaire in 1987/1988, 34% (891/2598) who attended religious services less than once per month or never and 23% (451/1946) who attended religious services at least once per month reported current smoking (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.5-2.0; P<.001). This association between less frequent attendance at religious services and current smoking was found in most denominations and remained significant after adjusting for potential confounding variables (OR, 1.5; 95% CI, 1.3-1.8; P<.001). During 3-year follow-up, nonsmokers who reported little or no religious involvement had an increased risk of smoking initiation (adjusted OR, 1.9; 95% CI, 1.3-2.7; P<.001). CONCLUSIONS: Young adults who attend religious services have lower rates of current and subsequent cigarette smoking. The potential health benefits associated with religious involvement deserve further study.

Adolescent↗

PubMed2002

Bioastronautics: optimizing human performance through research and medical innovations.

A strategic use of resources is essential to achieving long-duration space travel and understanding the human physiological changes in space, including the roles of food and nutrition in space. To effectively address the challenges of space flight, the Bioastronautics Initiative, undertaken in 2001, expands extramural collaboration and leverages unique capabilities of the scientific community and the federal government, all the while applying this integrated knowledge to Earth-based problems. Integral to the National Aeronautics and Space Administration's missions in space is the reduction of risk of medical complications, particularly during missions of long duration. Cumulative medical experience and research provide the ability to develop evidence-based medicine for prevention, countermeasures, and treatment modalities for space flight. The early approach applied terrestrial clinical judgment to predict medical problems in space. Space medicine has evolved to an evidence-based approach with the use of biomedical data gathered and lessons learned from previous space flight missions to systematically aid in decision making. This approach led, for example, to the determination of preliminary nutritional requirements for space flight, and it aids in the development of nutrition itself as a countermeasure to support nutritional mitigation of adaptation to space.

Adaptation, Physiological↗

PubMed2002

Computer modelling of the chemical speciation of caesium, uranium(VI) and neptunium(V) in human duodenal fluids under fasting conditions.

A model simulating the human duodenal contents under physiologically realistic, fasting conditions was developed using the joint expert speciation system (JESS) computer program and database and used to investigate the chemical speciation of caesium, uranium(VI) and neptunium(V). Over the pH range 5.0-9.0, and the concentration range 5 x 10(-15) x 10(-5) mol dm(-3), caesium was predicted to occur predominantly as the absorbable free monovalent cation Cs+ (approximately 95%) with species such as CsHPO4- and CsCl representing the remainder. The presence or absence of sulphate at 2.1 x 10(-3) mol dm(-3) did not influence the predicted speciation. Uranium was predicted to be present entirely as a soluble, highly charged species, both in the absence and in the presence of sulphate. Between pH 5.0 and approximately 6.5 the UO2H2(PO4)2(2-) predominated, above this pH carbonate species, either UO2(CO3)4(6-) or, possibly, UO2(CO3)5(8-). At pH 8.0, and in the presence of sulphate, neptunium(V) was predicted to exist solely as the tetrasulphate species, whilst in the absence of sulphate, an array of negatively charged soluble carbonate species predominated. Studies over the pH range 5.0-9.0 predicted the formation of a spectrum of negatively charged carbonate and phosphate species, approximately 40% of the total neptunium was predicted to be present as the electrically net-neutral species NpO2HCO3 at pH6.0, approximately 20% at pH 7.0, approximately 10% at pH 7.5 and approximately 1% at pH 8.0. The observed speciation patterns of uranium and neptunium did not change over the concentration range 5 x 10(-15) - 5 x 10(-5) mol dm(-3) and no solid species were predicted to occur under the conditions simulated. Whether the predicted electrically net-neutral neptunium species or the uranium pentacarbonate species do actually occur under true physiological conditions remains to be established. The observed speciation patterns for caesium and uranium are consistent with the observed absorption of these elements by humans; however, the observations for neptunium appear to be equivocal.

Cesium Radioisotopes↗

PubMed2002

Advanced ultrasonic diagnosis of extremity trauma: the FASTER examination.

BACKGROUND: Ultrasound is of proven accuracy in abdominal and thoracic trauma and may be useful for diagnosing extremity injury in situations where radiography is not available such as military and space applications. We prospectively evaluated the utility of extremity ultrasound performed by trained, nonphysician personnel in patients with extremity trauma to simulate remote aerospace or military applications. METHODS: Patients with extremity trauma were identified by history, physical examination, and radiographic studies. Ultrasound examination was performed bilaterally by nonphysician personnel, blinded to radiographic results, with a portable ultrasound device using a 10- to 5-MHz linear probe. Images were videorecorded for later analysis against radiography by Fisher's exact test. RESULTS: There were 158 examinations performed in 95 patients. The average time of examination was 4 minutes. Ultrasound accurately diagnosed extremity injury in 94% of patients with no false-positive examinations; accuracy was greater in midshaft locations and least in the metacarpal/metatarsals. Soft tissue/tendon injury was readily visualized. CONCLUSION: Extremity ultrasound can be performed quickly and accurately by nonphysician personnel with excellent accuracy. Pulmonary ultrasound appears promising; blinded verification of the utility of ultrasound in patients with extremity injury should be performed to determine whether extremity and respiratory evaluation should be added to the FAST examination (the FASTER examination) and to verify the technique in remote locations such as military and aerospace applications.

Adult↗

PubMed2002

Racial and spatial relations as fundamental determinants of health in Detroit.

African Americans in the United States have a higher than average risk of morbidity and mortality, despite declining mortality rates for many causes of death for the general population. This article examines race-based residential segregation as a fundamental cause of racial disparities, shaping differences in exposure to, and experiences of, diseases and risk factors. The spatial distribution of racial groups, specifically the residential segregation of African Americans in aging urban areas, contributes to disparities in health by influencing access to economic, social, and physical resources essential to health. Using the Detroit metropolitan area as a case study, this article looks at the influences of the distribution of African American and white residents on access to these resources and discusses the implications for urban policies to reduce racial disparities in health status.

Black or African American↗

PubMed2002

Optical fiber properties of individual human cones.

The tuning properties of the ensemble of cone photoreceptors is due to the tuning properties of individual cones convolved with the disarray in pointing direction between the cones. We used direct imaging with the Rochester adaptive optics ophthalmoscope to directly image these properties in individual cones in living human eyes. We found that cone disarray is very small, accounting for less than 1% of the breadth of the tuning function of an ensemble of cones. The implication is that the optical fiber properties of an ensemble of cones mimic the tuning properties of a single cone.

Color Perception↗

PubMed2002

Calculated impact of higher-order monochromatic aberrations on retinal image quality in a population of human eyes.

We calculated the impact of higher-order aberrations on retinal image quality and the magnitude of the visual benefit expected from their correction in a large population of human eyes. Wave aberrations for both eyes of 109 normal subjects and 4 keratoconic patients were measured for 3-, 4-, and 5.7-mm pupils with a Shack-Hartmann sensor. Retinal image quality was estimated by means of the modulation transfer function (MTF) in white light. The visual benefit was calculated as the ratio of the MTF when the monochromatic higher-order aberrations are corrected to the MTF corresponding to the best correction of defocus and astigmatism. On average, the impact of the higher-order aberrations for a 5.7-mm pupil in normal eyes is similar to an equivalent defocus of approximately 0.3 D. The average visual benefit for normal eyes at 16 c/deg is approximately 2.5 for a 5.7-mm pupil and is negligible for small pupils (1.25 for a 3-mm pupil). The benefit varies greatly among eyes, with some normal eyes showing almost no benefit and others a benefit higher than 4 at 16 c/deg across a 5.7-mm pupil. The benefit for keratoconic eyes is much larger. The benefit at 16 c/deg is 12 and 3 for 5.7- and 3-mm pupils, respectively, averaged across four keratoconics. These theoretical benefits could be realized in normal viewing conditions but only under specific conditions.

Adult↗

PubMed2002

Method for optimizing the correction of the eye's higher-order aberrations in the presence of decentrations.

The use of a correcting element to compensate for higher-order aberrations in an optical system often requires accurate alignment of the correcting element. This is not always possible, as in the case of a contact lens on the eye. We propose a method consisting of partial correction of every aberration term to minimize the average variance of the residual wave-front aberration produced by Gaussian decentrations (translations and rotations). Analytical expressions to estimate the fraction of every aberration term that should be corrected for a given amount of decentration are derived. To demonstrate the application of this method, three examples are used to compare performance with total and with partial correction. The partial correction is more robust and always yields some benefit regardless of the amount of decentration.

Humans↗

PubMed2002

Visual performance after correcting the monochromatic and chromatic aberrations of the eye.

The development of technology to measure and correct the eye's higher-order aberrations, i.e., those beyond defocus and astigmatism, raises the issue of how much visual benefit can be obtained by providing such correction. We demonstrate improvements in contrast sensitivity and visual acuity in white light and in monochromatic light when adaptive optics corrects the eye's higher-order monochromatic aberrations. In white light, the contrast sensitivity and visual acuity when most monochromatic aberrations are corrected with a deformable mirror are somewhat higher than when defocus and astigmatism alone are corrected. Moreover, viewing conditions in which monochromatic aberrations are corrected and chromatic aberrations are avoided provides an even larger improvement in contrast sensitivity and visual acuity. These results are in reasonable agreement with the theoretical improvement calculated from the eye's optical modulation transfer function.

Adult↗

PubMed2002

Calculated impact of higher-order monochromatic aberrations on retinal image quality in a population of human eyes.

Adult↗

PubMed2002

Racial/ethnic variations in women's health: the social embeddedness of health.

This article provides an overview of the magnitude of and trends in racial/ethnic disparities in health for women in the United States. It emphasizes the importance of attending to diversity in the health profiles and populations of minority women. Socioeconomic status is a central determinant of racial/ethnic disparities in health, but several other factors, including medical care, geographic location, migration and acculturation, racism, and exposure to stress and resources also play a role. There is a need for renewed attention to monitoring, understanding, and actively seeking to eliminate racial/ethnic disparities in health.

Acculturation↗

PubMed2002

Optimal indicators of socioeconomic status for health research.

OBJECTIVES: In this study we examined the relationship between indicators of socioeconomic status (SES) and mortality for a representative sample of individuals. METHODS: The sample included 3734 individuals aged 45 and older interviewed in 1984 in the Panel Study of Income Dynamics. In the current study, mortality was tracked between 1984 and 1994 and is related to SES indicators of education, occupation, income, and wealth. RESULTS: Wealth and recent family income were the indicators that were most strongly associated with subsequent mortality. These associations persisted after we controlled for the other SES indicators and were stronger for women than for men and for non-elderly than for elderly individuals. CONCLUSIONS: We found that the economic indicators of SES were usually as strongly associated with mortality as, if not more strongly associated with mortality than, the more conventional indicators of completed schooling and occupation.

Age Factors↗

PubMed2001

The biomedical challenges of space flight.

Space medicine has evolved considerably through past U.S. missions. It has been proven that humans can live and work in space for long durations and that humans are integral to mission success. The space medicine program of the National Aeronautics and Space Administration (NASA) looks toward future long-duration missions. Its goal is to overcome the biomedical challenges associated with maintaining the safety, health, and optimum performance of astronauts and cosmonauts. This program investigates the health effects of adaptation to microgravity: the nature of their pathologies, the effects of microgravity on pathophysiology, and the alterations in pharmacodynamics and treatment. A critical capability in performing research is the monitoring of the health of all astronauts and of the spacecraft environment. These data support the evidence-based approach to space medicine, incorporating past studies of microgravity-related conditions and their terrestrial counterparts. This comprehensive approach will enable safe and effective exploration beyond low Earth orbit.

Adaptation, Physiological↗