Standing on the shoulders of a giant: The legacy of Robert M. Sellers.

Robert M. Sellers, PhD, most known for his influential and highly cited Multidimensional Model of Racial Identity (MMRI), is one of the most prolific and foundational Black scholars in psychology. From racial identity theory development and measurement to conceptual and methodological innovations in studying the lived experiences of Black people, Sellers' scholarship centers on the lives of Black communities. Sellers' mentorship and contributions to the professional development of scholars and professionals of color have supported and catalyzed new intergenerational knowledge building by these scholars, ensuring a perpetuating and far-reaching legacy in psychology. In this article, we: (a) celebrate Sellers' enduring contribution to the racial identity literature and its profound impact on psychology as a discipline as well as numerous subfields of psychology, (b) outline his contributions to the racial socialization literature, (c) describe methodological innovations in racial identity and racial socialization research advanced through his scholarship, and (d) summarize his contributions in professional development and mentorship and his leadership roles. Sellers' scholarly contributions and mentorship have transformed the discipline of psychology and the social sciences broadly speaking, making him one of the most influential psychologists in the modern era. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Common injuries in the child or adolescent athlete.

As more primary care physicians enter the field of Sports Medicine, they will inevitably encounter more injured young athletes than what they may have experienced in their private practices. Recognizing the differences that exist between the young athlete and adult is essential in properly diagnosing and rehabilitating these athletes. As mentioned in our previous article (Caring for the School-Aged Athlete, Primary Care, December 1994), comprehensive care of the young athlete can be quite involved and somewhat different from care of the adult population. This article focuses on some specific injuries unique to younger, skeletally immature athletes, while mentioning the differential diagnosis of some of the other common sports injuries shared by both younger and older athletes.

Cellular expression of the C5a anaphylatoxin receptor (C5aR): demonstration of C5aR on nonmyeloid cells of the liver and lung.

The small-complement C5 activation fragment, C5a, is a potent phlogistic molecule that, on binding to the C5a Receptor (C5aR), mediates contraction of smooth muscle, enhances vascular permeability, and promotes leukocyte functions such as directed chemotaxis, degranulation, mediator release, and production of superoxide anions. Although C5aR expression has traditionally been thought to be limited primarily to myeloid blood cells, including neutrophils, monocytes, macrophages, and eosinophils, we report here that C5aR is expressed by liver and lung cells as well as by cells in several other tissues. By Northern blot analysis, it was determined that mouse liver, baboon liver, human liver, and the human hepatoma-derived cell line HepG2 express a normal size (2.3 kb) C5aR mRNA; in HepG2 cells, the quantity of C5aR mRNA was comparable to that contained in dbcAMP-differentiated U937 cells. HepG2 cells were demonstrated to express the C5aR on their cell surface by flow cytometric and immunofluorescence analyses as well as by 125I-C5a binding assays. The binding data indicated that HepG2 cells express a single class of C5aR with a Kd of 1.18 nM and approximately 28,000 receptors per cell. In vivo expression of C5aR in human liver cells was demonstrated by in situ hybridization and immunohistochemistry analyses. Northern blot analysis of murine and baboon organs shows that, in addition to the liver, other tissues express C5aR mRNA in significant quantities, including the spleen, lung, heart, kidney, and intestine. Moreover, mice treated with LPS show a large increase in C5aR mRNA in all these tissues except the intestine. Immunostaining of human lung tissue demonstrated that bronchial and alveolar epithelial cells, as well as vascular smooth muscle and endothelial cells, also express the C5aR. Collectively, these data indicate that the C5aR is expressed in several different types of cells in liver and lung, and in yet undetermined cell types in spleen, heart, intestine, and kidney. Furthermore, these data suggest that the C5a anaphylatoxin mediates previously unrecognized functions by binding to tissue cells that express the C5aR.

Caring for the school-aged athlete.

Younger athletes are participating in more activities today than ever before. The primary care physician needs to fulfill the role of guiding these athletes into their activities safely with recommendations to help prevent injuries and other health conditions that may occur during their training and participation. Knowledge covering preparticipation examinations, cardiovascular concerns, nutrition, maturation, and general rehabilitation of injuries will be necessary for the care of these younger athletes. This article provides a general overview of these areas.

Cellular and peptide requirements for in vitro clonal deletion of immature thymocytes.

Thymocytes from DO10 T-cell-receptor transgenic mice undergo apoptosis, or programmed cell death, when chicken ovalbumin-(323-339) peptide is administered in vivo. Using DO10 mice thymocytes, we have now developed a simple in vitro model system that recapitulates the in vivo clonal-deletion process. When transgenic thymocytes were cocultured with fibroblasts, B cells, or thymic nurse cell lines (all bearing I-Ad) in the presence of chicken ovalbumin-(323-339), deletion of the transgenic TCR+CD4+CD8+ thymocytes was seen within 8-20 hr. Thymocytes designed to bear I-Ad on their surface could mediate the deletion themselves. Thus, thymocyte clonal deletion entirely depends on the stage at which the thymocytes are vulnerable to the onset of apoptosis, rather than on the nature of the peptide antigen-presenting cells. Furthermore, thymic nurse cell line TNC-R3.1 could cause deletion, strongly suggesting that some thymic epithelial/stromal components are potentially capable of participating in negative selection. In all cases examined, little deletion could be induced at a peptide concentration less than 10 nM, thus defining the minimum amount of peptide antigen required for negative selection. The peptide-dependent in vitro negative-selection system will allow further dissection of the molecular and cellular processes involved in clonal deletion due to apoptosis in the thymus.

Transient ischemic attacks: their frequency in the Lehigh Valley.

The incidence of transient ischemic attacks (TIAs) in the Lehigh Valley was analyzed using the Lehigh Valley Stroke Register based on data collected between July 1, 1982, and June 30, 1986. The overall average annual incidence rate was 22.9 per 100,000 population, and 23.2 and 22.5 per 100,000 population in men and women, respectively. Men had a statistically significant higher age-specific rate of TIAs than women. Our incidence appears to be lower than that reported in earlier studies but, because of methodologic differences, only continued observations in our population and in similar populations using a standardized methodology will resolve the question of whether TIA frequency is, in fact, declining.

Stroke in the Lehigh Valley: racial/ethnic differences.

We investigated black/white differences in stroke rate (standardized morbidity), severity, and subtype, and the relative frequencies of 5 primary risk factors (hypertension, diabetes, myocardial infarction, other heart diseases, and transient ischemic attack [TIA]) using the Lehigh Valley Stroke Register. Blacks had a statistically significant higher, age-adjusted rate of stroke than whites. We found no differences in stroke severity using our measures but blacks had a statistically higher proportion of lacunar stroke, while whites had a higher proportion of embolic stroke. There were no differences in proportions of thrombotic stroke or intracerebral hemorrhage. The relative frequencies of hypertension, myocardial infarction, other heart diseases, and diabetes were higher for blacks, while the relative frequency of TIA was higher for whites. These observations are consistent with other reports that blacks have a higher frequency of stroke and tend to have more small-vessel cerebrovascular pathology than whites.

Stroke in the Lehigh Valley: risk factors for recurrent stroke.

Age-specific risk of recurrent stroke for various risk factors, calculated independently, was estimated using the first year of data from the Lehigh Valley Stroke Register. The register is based on a population of more than one-half million. Among the risk factors examined, the highest overall risk of recurrent stroke, 41.4, occurred with a history of at least one transient ischemic attack (TIA). After myocardial infarction (MI), the relative risk of a recurrent stroke was 8.0, while with all other heart diseases combined it was 8.4. With diabetes, the relative risk of a recurrent stroke was 5.6; with hypertension, it was 4.5. The relative risk increased with age after TIA and MI, but not for other heart disease, diabetes, and hypertension, except in the 85+-year-old age group.

The Lehigh Valley Stroke Program: establishing a communitywide, hospital-based stroke register.

A communitywide, hospital-based stroke register has been established in the Lehigh Valley of Pennsylvania and New Jersey. The Lehigh Valley has about 600,000 inhabitants and is geographically somewhat isolated. Ninety-five percent of the people are white, and the population has an age-sex distribution like that of the United States as a whole. All patients falling into any of nine diagnostic categories of stroke or transient ischemic attack are registered on admission to a hospital, and medical, social, and demographic data are abstracted onto precoded data forms. A single neurologist assigns definitive diagnoses according to standardized criteria after reviewing all of the medical data. The stroke register provides a new and powerful tool for collecting population-based data on a large number of cases in a short-time. After adjusting for demographic differences, epidemiologic studies can be carried out that may be generalizable to the entire United States. Several organizational aspects of the register and its operation are described in this report, and examples of the types of information and statistics readily calculable from the data in the register are given. The completeness of the stroke ascertainment and the large population registered also offer an excellent opportunity for any interested researcher to investigate the relationships between medical, social, and demographic conditions on the one hand and stroke risk on the other; to study the efficacy of prevention and treatment programs; and to determine health care provision requirements in a well-defined population.

Stroke in the Lehigh Valley: incidence based on a community-wide hospital register.

Since July 1982 a population-based study of stroke has been carried out in the Lehigh Valley, a region in Pennsylvania and New Jersey, USA, with 580,000 people. During the first year, the annual incidence rates of stroke and transient ischemic attack were 167 and 49 per 100,000 population, respectively. Cerebral thrombosis, embolus, cerebral hemorrhage and subarachnoid hemorrhage accounted for 76, 13, 8 and 3% of the strokes, respectively. The overall incidence rate and distribution of stroke by type agree well with other population-based studies. The large size of the population in the Lehigh Valley means that information on the epidemiology of stroke, as well as the effects of various therapies on stroke frequency and outcome, can be collected in a shorter period of time than in most other communities studied to date. Finally, an assessment of concordance in diagnosis between attending physicians and a neurologist using standardized criteria was possible for the entire community.