University of Massachusetts Boston

About: University of Massachusetts Boston is a education organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Population & Health care. The organization has 6541 authors who have published 12918 publications receiving 411731 citations. The organization is also known as: UMass Boston.

Too much of a good thing: retinoic acid as an endogenous regulator of neural differentiation and exogenous teratogen.

Abstract: Retinoic acid (RA) is essential for both embryonic and adult growth, activating gene transcription via specific nuclear receptors. It is generated, via a retinaldehyde intermediate, from retinol (vitamin A). RA levels require precise regulation by controlled synthesis and catabolism, and when RA concentrations deviate from normal, in either direction, abnormal growth and development occurs. This review describes: (i) how the pattern of RA metabolic enzymes controls the actions of RA; and (ii) the type of abnormalities that result when this pattern breaks down. Examples are given of RA control of the anterior/posterior axis of the hindbrain, the dorsal/ventral axis of the spinal cord, as well as certain sex-specific segments of the spinal cord, using varied animal models including mouse, quail and mosquitofish. These functions are highly sensitive to abnormal changes in RA concentration. In rodents, the control of neural patterning and differentiation are disrupted when RA concentrations are lowered, whereas inappropriately high concentrations of RA result in abnormal development of cerebellum and hindbrain nuclei. The latter parallels the malformations seen in the human embryo exposed to RA due to treatment of the mother with the acne drug Accutane (13-cis RA) and, in cases where the child survives beyond birth, a particular set of behavioural anomalies can be described. Even the adult brain may be susceptible to an imbalance of RA, particularly the hippocampus. This report shows how the properties of RA as a neural induction agent and organizer of segmentation can explain the consequences of RA depletion and overexpression.

Like Father, Like Son: Young Children's Understanding of How and Why Offspring Resemble Their Parents

Abstract: 4 studies investigated the broad claim that preschoolers understand biological inheritance. In Study 1, 4-7-year-old children were told a story in which a boy was born to one man and adopted by another. The biological father was described as having one set of features (e.g., green eyes) and the adoptive father as having another (e.g., brown eyes). Subjects were asked which man the boy would resemble when he grew up. Preschoolers showed little understanding that selective chains of processes mediate resemblance to parents. It was not until age 7 that children substantially associated the boy with his biological father on physical features and his adoptive father on beliefs. That is, it was not until age 7 that children demonstrated that they understood birth as part of a process selectively mediating the acquisition of physical traits and learning or nurturance as mediating the acquisition of beliefs. In Study 2, subjects were asked whether, as a boy grew up, various of his features could change. Children generally shared our adult intuitions, indicating that their failure in Study 1 was not due to their having a different sense of what features can change. Studies 3 and 4 replicated Study 1, with stories involving mothers instead of fathers and with lessened task demands. Taken together, the results of the 4 studies refute the claim that preschoolers understand biological inheritance. The findings are discussed in terms of whether children understand biology as an autonomous cognitive domain.

Racial Differences in the Effects of Campus Racial Climate on Degree Completion: A Structural Equation Model

Abstract: Racial minority student persistence is of paramount importance to higher education policymakers and practitioners. This study was aimed at understanding racial differences in the direct and indirect effects of campus racial climate on degree completion using structural equation modeling techniques and a nationally representative sample. The findings of this analysis highlight the importance of examining conditional effects and indicate that students from disparate racial backgrounds may experience and react to their campus racial climates in different ways. Implications for research and practice are discussed.

Sex ratios in tropical forest trees.

Abstract: Sex ratios of dioecious plants often depart significantly from unity (Correns, 1922; Dzhapardize, 1967; Godley, 1964; Pauley and Mennel, 1957; Rathore, 1969). Explanations for these deviations have usually been sought in the genetics of sexdetermination (for a review see Westergaard, 1958; Lloyd, 1974). However, biased sex ratios may also have an ecological basis, and thereby have important implications for the reproductive ecology of the subject plants. Yet, relatively few studies have considered the ecological aspects of deviant sex ratios (Harris, 1968; Lloyd, 1973; Lloyd and Webb, 1977; Putwain and Harper, 1972). Here we present data on the sex ratios of 23 species of tropical forest trees and attempt to explain these ratios with respect to certain ecological factors. Our study may be considered noteworthy because most previous studies of sex ratios in dioecious species have been conducted on plants of temperate regions. Since dioecism is more common in tropical than in temperate ecosystems (Bawa and Opler, 1975; see also Ashton, 1969; Tomlinson, 1973), studies of sex ratios in tropical trees should contribute significantly toward an understanding of deviant sex ratios in flowering plants.

A current analysis of chemotherapy strategies for the treatment of human African trypanosomiasis

Abstract: Despite the recent advances in drug research, finding a safe, effective, and easy to use chemotherapy for human African trypanosomiasis (HAT) remains a challenging task. The four current anti-trypanosomiasis drugs have major disadvantages that limit more widespread use of these drugs in the endemic regions of sub-Saharan Africa. Pentamidine and suramin are limited by their effectiveness against the only first stage of Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, respectively. In addition, melarsoprol and eflornithine (two second stage drugs) each have disadvantages of their own. The former is toxic and has increasing treatment failures while the latter is expensive, laborious to administer, and lacks efficacy against T. b. rhodesiense. Furthermore, melarsoprol’s toxicity and decreasing efficacy are glaring problems and phasing out the drug as a frontline treatment against T. b. gambiense is now possible with the emergence of competent, safe combination chemotherapies such as nifurtimox–eflornithine combination treatment (NECT). The future of eflornithine, on the other hand, is more promising. The drug is useful in the context of combination chemotherapy and potential orally administered analogues. Due to the limits of monotherapies, greater emphasis should be placed on the research and development of combination chemotherapies, based on the successful clinical tests with NECT and its current use as a frontline anti-trypanosomiasis treatment. This review discussed the current and future chemotherapy strategies for the treatment of HAT.