Meeting threats to global health: a call for American leadership

Although the application of major biomedical advances has yielded spectacular results for individual health, there has been little improvement in the health of whole populations. There is a "back to the future" irony in the fact that at the inception of the 21st century, the eruption and spread of a multitude of "old" and "new" infectious diseases has become the most serious global threat to the health of humankind. At this historical juncture, the United States is the country with the most potential for favorably influencing global health and health care. Although there are historical, cultural, economic, and political factors that impede the United States from rising to this challenge, there is both a moral imperative and a rational long-term self-interest basis for the U.S. medical profession and government to exercise leadership in facing the health challenges of tragic and genocidal proportions that threaten everyone in an increasingly interdependent world.     

Estimation of effective population size and detection of a recent population decline coinciding with habitat fragmentation in a ground beetle

We assess the impact of habitat fragmentation on the effective size (N(e)) of local populations of the flightless ground beetle Carabus violaceus in a small (<25 ha) and a large (>80 ha) forest fragment separated by a highway. N(e) was estimated based on the temporal variation of allele frequencies at 13 microsatellite loci using two different methods. In the smaller fragment, N(e) estimates ranged between 59 and a few hundred, whereas values between 190 and positive infinity were estimated for the larger fragment. In both samples, we detected a signal of population decline, which was stronger in the small fragment. The estimated time of onset of this N(e) reduction was consistent with the hypothesis that recent road constructions have divided a continuous population into several isolated subpopulations. In the small fragment, N(e) of the local population may be so small that its long-term persistence is endangered.     

Localization of the microtubule end binding protein EB1 reveals alternative pathways of spindle development in Arabidopsis suspension cells

In a previous study on Arabidopsis thaliana suspension cells transiently infected with the microtubule end binding protein AtEB1a-green fluorescent protein (GFP), we reported that interphase microtubules grow from multiple sites dispersed over the cortex, with plus ends forming the characteristic comet-like pattern. In this study, AtEB1a-GFP was used to study the transitions of microtubule arrays throughout the division cycle of cells lacking a defined centrosome. During division, the dispersed origin of microtubules was replaced by a more focused pattern with the plus end comets growing away from sites associated with the nuclear periphery. The mitotic spindle then evolved in two quite distinct ways depending on the presence or absence of the preprophase band (PPB): the cells displaying outside-in as well as inside-out mitotic pathways. In those cells possessing a PPB, the fusion protein labeled material at the nuclear periphery that segregated into two polar caps, perpendicular to the PPB, before nuclear envelope breakdown (NEBD). These polar caps then marked the spindle poles upon NEBD. However, in the population of cells without PPBs, there was no prepolarization of material at the nuclear envelope before NEBD, and the bipolar spindle only emerged clearly after NEBD. Such cells had variable spindle orientations and enhanced phragmoplast mobility, suggesting that the PPB is involved in a polarization event that promotes early spindle pole morphogenesis and subsequent positional stability during division. Astral-like microtubules are not usually prominent in plant cells, but they are clearly seen in these Arabidopsis cells, and we hypothesize that they may be involved in orienting the division plane, particularly where the plane is not determined before division.     

The effects and comparative differences of neutrophil specific chemokines on neutrophil chemotaxis of the neonate

Neutrophil specific chemokines are potent chemoattractants for neutrophils. IL-8/CXCL8 is the most extensively studied member of this group, and its concentrations increase during inflammatory conditions of the newborn infant including sepsis and chronic lung disease. A significant amount of information exists on the effects of IL-8/CXCL8 on neutrophil chemotaxis of neonates, but little is known about the other neutrophil specific chemokines. The aim of this study was to determine the relative potency of the neutrophil specific chemokines on chemotaxis of neonatal neutrophils and to compare this effect with the effect on adult neutrophils. Neutrophils were isolated from cord blood or healthy adult donors and incubated in a Neuroprobe chemotaxis chamber. Chemokine concentrations ranging from 1-1000 ng/mL were used. Differences in chemotactic potency existed among the seven neutrophil specific chemokines. Specifically, at 100 ng/mL, the order was IL-8/CXCL8>GRO-alpha/CXCL1>GCP-2/CXCL6>NAP-2/CXCL7>ENA-78/CXCL5>GRO-gamma/CXCL2>GRO-beta/CXCL3. This pattern was observed for adult and neonatal neutrophils. We conclude that (1) neutrophils from cord blood exhibit the same pattern of potency for each ELR chemokine as neutrophils from adults, and (2) migration of neonatal neutrophils is significantly less than that of adults at every concentration examined except the lowest (1 ng/mL).     

Effects of brassinosteroids on microspore embryogenesis in <Emphasis Type="Italic">Brassica</Emphasis> species

Summary Experiments were conducted to determine the effects of brassinosteroids on microspore embryogenesis in Brassica species. Two compounds, 24-epibrassinolide (EBR) and brassinolide (BL), were evaluated. An increase in embryogenesis was observed in all Brassica napus lines evaluated, including Topas 4079 and several recalcitrant cultivars: Garrison, Westar, and Allons. Microspore embryogenesis, calculated as the number of embryos at 21 d of culture, was increased in the recalcitrant cultivars up to 12 times that of the control. An increase in microspore embryogenesis was also observed for B. juncea when EBR or BL was added to the culture medium. In constrast, no significant increases in embryogenesis was observed for several other Brassica species evaluated (i.e. B. carinata, B. nigra, and B. rapa). The addition of brassinosteroids to the induction media did not affect the subsequent conversion of the embryos to plantlets, but did appear to influence chromosome doubling.     

Diversity of mesophilic clostridia in Costa Rican soils

Costa Rica is located in the Tropic, one of the most biologically diverse regions of the world; its soil is an important epicenter of biodiversity and Clostridium spp. are among the most frequent bacteria. The diversity of clostridia in Costa Rican soils and its possible association with geographic zone, pH or type of soil was studied in 117 soil samples: 18 from the Atlantic Zone, 30 from the Central Plateau, 30 from the Dry Pacific, 13 from the North Zone, and 26 from the South Pacific. The pH and the mesophilic clostridia species were determined for each sample. For bacterial isolation, a selective methodology for spores and pre-reduced anaerobically sterilized media were used. A total of 1945 strains of clostridia were isolated, 98% were identified and corresponded to 54 species; the most frequent species were C. subterminale (56%), C. oceanicum (51%), C. bifermentans and C. glycolicum (50%, each), C. sporogenes (49%), and C. sordellii (42%). An average of 7.1 species per sample was obtained; the Atlantic Zone showed the greatest diversity: 8.6 species per sample and a total of 45 species. Except for C. chauvoei, all described toxigenic clostridia species were isolated; C. sordellii (42%) and C. perfringens (38%) were the most frequent. No statistical relation could be established between geographic zone or type of soil and any species, showing that clostridia had a high adaptation capability to grow in different soil conditions; only some clostridia were isolated from very acidic samples while others from soils with a wide range of pH. In general, a uniform distribution of most species and a high variety of clostridia in Costa Rican soils were observed, in agreement with the high biodiversity described for other living beings in this country.     

Ethics guidelines for research with the recently dead

The objective of the multidisciplinary expert Consensus Panel on Research with the Recently Dead (CPRRD) was to craft ethics guidelines for research with the recently dead. The CPRRD recommends that research with the recently dead: (i) receive scientific and ethical review and oversight; (ii) involve the community of potential research subjects; (iii) be coordinated with organ procurement organizations; (iv) not conflict with organ donation or required autopsy; (v) use procedures respectful of the dead; (vi) be restricted to one procedure per day; (vii) preferably be authorized by first-person consent, though both general advance research directives and surrogate consent are acceptable; (viii) protect confidentiality; (ix) not impose costs on subjects' estates or next of kin and not involve payment; (x) clearly explain ultimate disposition of the body.