Melanoma and lymphocyte cell-specific targeting incorporated into a heat shock protein cage architecture

Protein cages, including viral capsids, ferritins, and heat shock proteins (Hsps), can serve as nanocontainers for biomedical applications. They are genetically and chemically malleable platforms, with potential as therapeutic and imaging agent delivery systems. Here, both genetic and chemical strategies were used to impart cell-specific targeting to the Hsp cage from Methanococcus jannaschii. A tumor vasculature targeting peptide was incorporated onto the exterior surface of the Hsp cage. This protein cage bound to alpha(v)beta(3) integrin-expressing cells. Cellular tropism was also imparted by conjugating anti-CD4 antibodies to the exterior of Hsp cages. These Ab-Hsp cage conjugates specifically bound to CD4(+) cells. Protein cages have the potential to simultaneously incorporate multiple functionalities, including cell-specific targeting, imaging, and therapeutic agent delivery. We demonstrate the simultaneous incorporation of two functionalities, imaging and cell-specific targeting, onto the Hsp protein cage.

Proteomic mapping of the hyperthermophilic and acidophilic archaeonSulfolobus solfataricus P2

A proteomic map of Sulfolobus solfataricus P2, an archaeon that grows optimally at 80 degrees C and pH 3.2, was developed using high-resolution 2-DE and peptide mass fingerprinting. A total of 867 protein spots (659 aqueous Tris-soluble spots and 208 aqueous Tris-insoluble) were mapped over IPG 3-10, 4-7, and 6-11, with second-dimensional gels made of 8-18% polyacrylamide. Three hundred and twenty-four different gene products were represented by the 867 spots, with 274 gene products being identified in the Tris-soluble fractions and 100 gene products in the Tris-insoluble portion. Fifty gene products were found on gels from both fractions. Additionally, an average of 1.50 +/- 0.12 isoforms/protein was identified. This mapping study confirmed the expression of proteins involved in numerous metabolic, transport, energy production, nucleic acid replication, translation, and transcription pathways. Of particular interest, phosphoenolpyruvate carboxykinase (SSO2537) was detected even though the pathway for gluconeogenesis is unknown for this archaeon. Tris-soluble fractions contained many cytosolic proteins while Tris-insoluble fractions contained many membrane-associated proteins, including ABC transporters and an ATP synthase. This study provides an optimized 2-DE approach for investigating the biochemical pathways and post-translational modifications employed by Sulfolobus to survive in its extreme environment.

Enhanced local symmetry interactions globally stabilize a mutant virus capsid that maintains infectivity and capsid dynamics

Structural transitions in viral capsids play a critical role in the virus life cycle, including assembly, disassembly, and release of the packaged nucleic acid. Cowpea chlorotic mottle virus (CCMV) undergoes a well-studied reversible structural expansion in vitro in which the capsid expands by 10%. The swollen form of the particle can be completely disassembled by increasing the salt concentration to 1 M. Remarkably, a single-residue mutant of the CCMV N-terminal arm, K42R, is not susceptible to dissociation in high salt (salt-stable CCMV [SS-CCMV]) and retains 70% of wild-type infectivity. We present the combined structural and biophysical basis for the chemical stability and viability of the SS-CCMV particles. A 2.7-A resolution crystal structure of the SS-CCMV capsid shows an addition of 660 new intersubunit interactions per particle at the center of the 20 hexameric capsomeres, which are a direct result of the K42R mutation. Protease-based mapping experiments of intact particles demonstrate that both the swollen and closed forms of the wild-type and SS-CCMV particles have highly dynamic N-terminal regions, yet the SS-CCMV particles are more resistant to degradation. Thus, the increase in SS-CCMV particle stability is a result of concentrated tethering of subunits at a local symmetry interface (i.e., quasi-sixfold axes) that does not interfere with the function of other key symmetry interfaces (i.e., fivefold, twofold, quasi-threefold axes). The result is a particle that is still dynamic but insensitive to high salt due to a new series of bonds that are resistant to high ionic strength and preserve the overall particle structure.

The role of subunit hinges and molecular "switches" in the control of viral capsid polymorphism

The coat protein (CP) of cowpea chlorotic mottle virus assembles exclusively into a T=3 capsid in vivo and, under proper conditions, in vitro. The N-terminal domain of CP has been implicated in proper assembly and was viewed as a required switch for mediating hexamer and pentamer formation in T=3 assembly. We observed that a mutant CP lacking most of the N-terminal domain, NDelta34, assembles, in vitro, into statistically predictable numbers of: native-like T=3 capsids of 90 dimers; "T=2" capsids of 60 dimers; T=1 capsids of 30 dimers. We generated cryo-EM image reconstructions of each form and built pseudo-atomic models based on the subunits from the crystal structure of plant-derived T=3 virus allowing a detailed comparison of stabilizing interactions in the three assemblies. The statistical nature of the distribution of assembly products and the observed structures indicates that the N-terminus of CP is not a switch that is required to form the proper ratio of hexamers and pentamers for T=3 assembly; rather, it biases the direction of assembly to T=3 particles from the possibilities available to NDelta34 through flexible dimer hinges and variations in subunit contacts. Our results are consistent with a pentamer of dimers (PODs) nucleating assembly in all cases but subunit dimers can be added with different trajectories that favor specific T=3 or T=1 global particle geometries. Formation of the "T=2" particles appears to be fundamentally different in that they not only nucleate with PODs, but assembly propagates by the addition of mostly, if not exclusively PODs generating an entirely new subunit interface in the process. These results show that capsid geometry is flexible and may readily adapt to new requirements as the virus evolves.

The impact of rater effects on weighted composite scores under nested and spiraled scoring designs, using the multifaceted Rasch model

Constructed-response or open-ended tasks are increasingly used in recent years. Since these tasks cannot be machine-scored, variability among raters cannot be completely eliminated and their effects, when they are not modeled, can cast doubts on the reliability of the results. Besides rater effects, the estimation of student ability can also be impacted by differentially weighted tasks/items that formulate composite scores. This simulation study compares student ability estimates with their true abilities under different rater scoring designs and differentially weighted composite scores. Results indicate that the spiraled rater scoring design without modeling rater effects works as well as the nested design in which rater tendencies are modeled. As expected, differentially weighted composite scores have a confounding effect on student ability estimates. This is particularly true when open-ended tasks are weighted much more than the multiple-choice items and when rater effects interact with weighted composite scores.

Neural Progenitor Cell Transplants into the Developing and Mature Central Nervous System

When developing cell transplant strategies to repair the diseased or injured central nervous system (CNS), it is essential to consider host-graft interactions and how they may influence the outcome of the transplants. Recent studies have demonstrated that transplanted neural progenitor cells (NPCs) can differentiate and integrate morphologically into developing mammalian retinas. Is the ability to differentiate and to undergo structural integration into the CNS unique to specific progenitor cells, or is this plasticity a function of host environment, or both? To address these issues we have used the developing retina of the Brazilian opossum and have compared the structural integration of brain and retinal progenitor cells transplanted into the eyes at different developmental stages. The Brazilian opossum, Monodelphis domestica, is a small pouchless marsupial native to South America. This animal's lack of a pouch and fetal-like nature at birth circumvents the need for in utero surgical procedures, and thus provides an ideal environment in which to study the interactions between developing host tissues and transplanted NPCs. To test whether NPCs affect visual function we transplanted adult hippocampal progenitor cells (AHPCs) into normal, healthy adult rat eyes and performed noninvasive functional recordings. Monitoring of the retina and optic nerve over time by electroretinography and pupillometry revealed no severe perturbation in visual function in the transplant recipient eyes. Taken together, our findings suggest that the age of the host environment can strongly influence NPC differentiation and that transplantation of neural progenitor cells may be a useful strategy aimed at treating neurodegeneration and pathology of the CNS.

The effect of body mass index on patient outcomes in a medical ICU

STUDY OBJECTIVES

To examine the effect of patient body mass index (BMI) on outcome in intensive care.

DESIGN

In a prospective study, the patients were classified into groups based on the calculated BMI, as follows: BMI < 19.0 (n = 350), > or = 19.0 and < 25.0 (n = 663), > or = 25.0 and < 29.9 (n = 585), > or = 30.0 and < 40.0 (n = 396), and > or = 40.0 (n = 154). Groups were compared by age, APACHE (acute physiology and chronic health evaluation) II score, mortality, ICU length of stay (LOS), hospital LOS, number receiving ventilation, and ventilator-days. Adverse events including nosocomial pneumonia, ventilator-days per patient, failed extubations, and line-related complications were recorded.

SETTING

The study was conducted in a 9-bed medical ICU of a 650-bed tertiary care hospital.

MEASUREMENTS

Height and weight were prospectively recorded for the first ICU admission during a hospital stay.

RESULTS

Between January 1, 1997, and August 1, 2001, 2,148 of 2,806 patients admitted to the ICU had height and weight recorded. There were no differences in APACHE II score, mortality, ICU LOS, hospital LOS, number receiving ventilation, ventilator-days, average total cost, or average variable cost among the five groups. However, the severely obese patients were more frequently female and younger than those who were overweight and obese (p < 0.001). Adverse events were infrequent, but there were no differences between the obese/very obese compared with others.

CONCLUSION

BMI has minimal effects on ICU outcome after patients are admitted to a critical care unit.

Fabrication of degradable polymer scaffolds to direct the integration and differentiation of retinal progenitors

Retinal progenitor cells (RPCs) are self-renewing cells capable of differentiating into the different retinal cell types including photoreceptors, and they have shown promise as a source of replacement cells in experimental models of retinal degeneration. We hypothesized that a biodegradable polymer scaffold could deliver these cells to the subretinal space in a more organized manner than bolus injections, while also providing the graft with laminar organization and structural guidance channels. We fabricated highly porous scaffolds from blends of poly(L-lactic acid) and poly(lactic-co-glycolic acid) using a variety of techniques to produce pores oriented normal to the plane of the scaffold. RPCs were seeded on the polymer scaffolds and cultured for 14 days. Seeded scaffolds were then either fixed for characterization or used in an explant or in vivo rat model. The scaffolds were fully covered by RPCs in 3 days. Attachment of RPCs to the polymer scaffold was associated with down-regulation of immature markers and up-regulation of markers of differentiation. This suggests that the scaffold may promote differentiation of RPCs. The seeded cells elaborated cellular processes and aligned in the scaffold in conjunction with degenerating retinal explants. The cells also exhibited morphologies consistent with photoreceptors including a high degree of polarization of the cells. This data suggests that the scaffold may be a means to assist in the promotion of photoreceptor phenotypes. Implantation of the seeded scaffold into the rat eye is associated with increased RPC survival. Taken together, these data suggest that these polymer scaffolds provide a useful means for delivering RPCs to the subretinal space and may assist in the formation of retinal cell phenotypes, although it is clear that more cues are needed to direct the differentiation of RPCs into functional photoreceptors.

Transplantation of Neural Progenitor Cells into the Developing Retina of the Brazilian Opossum: An in vivo System for Studying Stem/Progenitor Cell Plasticity

In developing cell transplant strategies to repair the diseased or injured retina is essential to consider host-graft interactions and how they may influence the outcome of the transplants. In the present study we evaluated the influence of the host microenvironment upon neural progenitor cells (NPCs) transplanted into the developing and mature retina of the Brazilian opossum, Monodelphis domestica. Monodelphis pups are born in an extremely immature state and the neonatal pups provide a fetal-like environment in which to study the interactions between host tissues and transplanted NPCs. Three different populations of GFP-expressing NPCs were transplanted by intraocular injection in hosts ranging in age from 5 days postnatal to adult. Extensive survival, differentiation and morphological integration of NPCs were observed within the developing retina. These results suggest that the age of the host environment can strongly influence NPC differentiation and integration.

Regulating self-assembly of spherical oligomers

In multistep reactions, stability of intermediates is critical to the rate of product formation and a significant factor in generating kinetic traps. The capsid protein of cowpea chlorotic mottle virus (CCMV) can be induced to assemble into spherical particles of 30, 60, and 90 dimers. Based on examining assembly kinetics and reaction end points, we find that formation of uniform, ordered structures is not always a result of reactions that reach equilibrium. Equilibration or, alternatively, kinetic trapping can be identified by a straightforward analysis. Altering the assembly path of "spherical" particles is a means of controlling the distribution of products, which has broad applicability to self-assembly reactions.

Selective attachment and release of a chemotherapeutic agent from the interior of a protein cage architecture

The antitumor agent doxorubicin was covalently bound and selectively released in a pH dependent manner from the interior surface of a genetically modified small heat shock protein (Hsp) cage.

Discussion Suppers as a Means for Community Engagement

PURPOSE

This paper describes how Lehigh Valley Hospital and Health Network (LVHHN), a large tertiary care urban hospital, used discussion suppers as a means for community engagement designed to lead to community health improvement. An overview of the implementation of the project is described.

PROJECT

In 1996, with an awareness of the need to address population-based health improvement, the Dorothy Rider Pool Health Care Trust and LVHHN undertook a multiyear, multidimensional effort to improve health and quality of life in the Lehigh Valley of Pennsylvania. Data were obtained via a series of community and health assessments. Action-Oriented Community Diagnosis and the Behavioral Risk Factor Surveillance System survey, a national instrument, are 2 assessments discussed. The community was engaged through a series of discussion suppers in which community data were shared in a friendly, interactive fashion. The process included community definition of priorities from the data and the subsequent determination of corresponding actions (programs).

CONCLUSIONS

The success of these activities demonstrates the discussion suppers were an effective approach and that data can be shared with rural areas in ways that build partnerships and provide a basis for joint actions. This is increasingly important as communities expect our health care systems to provide care both within the hospital as well as outside its walls.

Effects of culturing on the population structure of a hyperthermophilic virus

The existence of a culturing bias has long been known when sampling organisms from the environment. This bias underestimates microbial diversity and does not accurately reflect the most ecologically relevant species. Until now no study has examined the effects of culture bias on viral populations. We have employed culture-independent methods to assess the diversity of Sulfolobus spindle-shaped viruses (SSVs) from extremely hyperthermal environments. This diversity is then compared to the viral diversity of cultured samples. We detected a clear culturing bias between environmental samples and cultured isolates. This is the first study identifying a culture bias in a viral population.

Interaction with capsid protein alters RNA structure and the pathway for in vitro assembly of cowpea chlorotic mottle virus

Viruses use sophisticated mechanisms to allow the specific packaging of their genome over that of host nucleic acids. We examined the in vitro assembly of the Cowpea chlorotic mottle virus (CCMV) and observed that assembly with viral RNA follows two different mechanisms. Initially, CCMV capsid protein (CP) dimers bind RNA with low cooperativity and form virus-like particles of 90 CP dimers and one copy of RNA. Longer incubation reveals a different assembly path. At a stoichiometry of about ten CP dimers per RNA, the CP slowly folds the RNA into a compact structure that can be bound with high cooperativity by additional CP dimers. This folding process is exclusively a function of CP quaternary structure and is independent of RNA sequence. CP-induced folding is distinct from RNA folding that depends on base-pairing to stabilize tertiary structure. We hypothesize that specific encapsidation of viral RNA is a three-step process: specific binding by a few copies of CP, RNA folding, and then cooperative binding of CP to the "labeled" nucleoprotein complex. This mechanism, observed in a plant virus, may be applicable to other viruses that do not halt synthesis of host nucleic acid, including HIV.

Viruses of hyperthermophilic Archaea

The viruses of Archaea are likely to be useful tools for studying host evolution, host biochemical pathways, and as tools for the biotechnology industry. Many of the viruses isolated from Archaea show distinct morphologies and genes. The euryarchaeal viruses show morphologies similar to the head-and-tail phage isolated from Bacteria; however, sequence analysis of viral genomes from Crenarchaea shows little or no similarity to previously isolated viruses. Because viruses adapt to host organism characteristics, viruses may lead to important discoveries in archaeal biochemistry, genetics, and evolution.

Differentiation and morphological integration of neural progenitor cells transplanted into the developing mammalian eye

Transplantation of neural stem/progenitor cells has been proposed as a novel approach for the replacement and repair of damaged CNS tissues. We have evaluated the influence of the host cellular microenvironment upon the survival, differentiation, and integration of neural progenitor cells transplanted into the CNS. Using this approach, we have investigated the fate of neural progenitor cells in vivo following transplantation into the developing mammalian eye. Murine brain progenitor cells (mBPCs) isolated from neonatal mice expressing the green fluorescent protein (GFP) transgene were transplanted into the eyes of Brazilian opossums (Monodelphis domestica). Monodelphis pups are born in an extremely immature, fetal-like state. The eyes of neonatal pups provide a fetal-like environment in which to study cellular interactions between host tissues and transplanted neural progenitor cells. mBPCs were transplanted by intraocular injection in hosts ranging in age from 5 days postnatal to adult. The transplanted cells were easily identified because of their GFP fluorescence. Extensive survival, differentiation, and morphological integration of mBPCs within the host tissue was observed. We found that the younger retinas provided a more supportive environment for the morphological integration of the transplanted mBPCs. Cells with morphologies characteristic of specific retinal cell types were observed. Moreover, some transplanted mBPCs were labeled with antibodies characteristic of specific neural/retinal phenotypes. These results suggest that the host environment strongly influences progenitor cell differentiation and that transplantation of neural progenitor cells may be a useful approach aimed at treating degeneration and pathology of the CNS.

Impact of immediate reconstruction on the local recurrence of breast cancer after mastectomy

The incidence of local recurrence of breast cancer in women who underwent mastectomy with or without reconstruction was examined. All female mastectomy patients were followed-up in a 10-year retrospective review. Groups consisted of patients who had mastectomy, mastectomy with immediate reconstruction, or delayed reconstruction. Reconstruction was performed using prostheses, latissimus dorsi musculocutaneous flaps with or without implants, or transverse rectus abdominis musculocutaneous flaps. Charts were reviewed for local breast cancer recurrence. Statistical analysis was performed using Pearson's chi-square and analysis of variance. Of the 1,444 mastectomies performed from 1988 to 1997, 1,262 breasts (87%) were not reconstructed, 182 (13%) were reconstructed, 158 (87%) were immediately reconstructed, and 24 (13%) were reconstructed later. There were no recurrences in the delayed reconstruction group, two recurrences (1.3%) in the immediate reconstruction group, and nine recurrences (0.7%) in the mastectomy without reconstruction group (p=0.746). Analyses of an additional time period from 1992 to 2000 yielded similar results. There is little relationship between local recurrence of breast cancer after mastectomy and reconstruction.

Transplantation of EGF-responsive neurospheres from GFP transgenic mice into the eyes of rd mice

The isolation of stem cells from various regions of the central nervous system has raised the possibility of using them as a donor cell source for cell transplantation, where they offer great promise for repair of the diseased brain, spinal cord, and retina. Here, we have studied the migration, integration, and differentiation of EGF-responsive neurospheres isolated from the brains of green fluorescent protein transgenic mice and transplanted into the eyes of mature rd mice, a model of retinitis pigmentosa. While grafts of freshly isolated postnatal day 8 retina expressed many markers characteristic of mature retina (e.g. rhodopsin, protein kinase C), very few of the grafted cells migrated into host retina. EGF-responsive neurospheres, conversely, readily migrated into and integrated with the remaining host retina, but showed a very limited ability to differentiate into mature retinal neurons. While the progenitor cells used here show remarkable ability to integrate with host retina and develop some attributes of retinal cells, the failure to fully differentiate into retinal cells suggests that they already express some level of terminal commitment that precludes using them to replace lost photoreceptors.

Quantitative studies on the peroxidation of human low-density lipoprotein initiated by superoxide and by charged and neutral alkylperoxyl radicals

Rates of peroxidation of human LDL and rates of consumption of the LDL's alpha-tocopherol (TocH) have been measured at 37 degrees C. Peroxidation was initiated by radicals generated in the aerated aqueous phase at known rates by thermal decomposition of appropriate precursors: superoxide (O2(*-)/HOO(*)) from a hyponitrite and alkylperoxyls (ROO(*), two positively charged, one negatively charged and one neutral) from azo compounds. The efficiencies of escape from the solvent cage of the geminate pair of neutral carbon-centered radicals was found to be 0.1, but it was 0.5 for the three charged radicals, a result attributed to radical/radical Coulombic repulsion within the cage. All four alkylperoxyls initiated and terminated tocopherol-mediated peroxidation (TMP) with about equal efficiency and essentially all of these radicals that were generated were consumed in these two reactions. TMP is a radical chain process, and when initiated by the alkylperoxyls, the rate of LDL peroxidation was faster in the early stages while TocH was present than later, after all of this "antioxidant" had been consumed. In contrast, only about 3-4% of the generated superoxide radicals reacted in any measurable fashion with TocH-containing LDL at pH's from 7.6 to 6.5 and peroxidation was much slower than with a similar rate of generation of alkylperoxyls. After all the TocH had been consumed, LDL peroxidation was negligible at pH 7.6 and 7.4, but at pH 6.8 and 6.5, the peroxidation rates showed a large increase over the rates while the TocH had been present. That is, endogenous TocH behaves as an antioxidant in LDL subjected to attack by the physiologically relevant superoxide radical, whereas TocH behaves as a prooxidant in LDL subjected to attack by the probably far less physiologically important alkylperoxyls. Rates of LDL peroxidation initiated by superoxide increased as the pH was decreased, and the results are consistent with the initiation of peroxidation of fresh LDL occurring via H-atom abstraction from TocH by HOO(*) to form the Toc(*) radical and termination by reaction of O2(*-) with Toc(*), a process that occurs partly by addition leading to TocH consumption and partly by electron plus proton transfer leading to the regeneration of TocH.

Viruses from extreme thermal environments

Viruses of extreme thermophiles are of great interest because they serve as model systems for understanding the biochemistry and molecular biology required for life at high temperatures. In this work, we report the discovery, isolation, and preliminary characterization of viruses and virus-like particles from extreme thermal acidic environments (70-92 degrees C, pH 1.0-4.5) found in Yellowstone National Park. Six unique particle morphologies were found in Sulfolobus enrichment cultures. Three of the particle morphologies are similar to viruses previously isolated from Sulfolobus species from Iceland and/or Japan. Sequence analysis of their viral genomes suggests that they are related to the Icelandic and Japanese isolates. In addition, three virus particle morphologies that had not been previously observed from thermal environments were found. These viruses appear to be completely novel in nature.

Cardiac steroidogenesis in the normal and failing heart

The present study explores the possibility of local de novo aldosterone production in normal and failing hearts (human and mouse) and the regulation of such putative cardiac steroidogenesis. Total RNA was isolated from human tissue from failing hearts taken at the time of cardiac transplantation, from normal hearts obtained at autopsy, and from normal and pressure-overloaded mouse hearts. Vascular smooth muscle cells from human artery and vein were also analyzed. RNA was reverse transcribed and probed with specific primers for side-chain cleavage enzyme (CYP11A), 3beta-hydroxysteroid dehydrogenase, aldosterone synthase (CYP11B2), 11beta-hydroxylase (CYP11B1), steroidogenic factor-1, and steroid acute regulatory protein. CYP11A, 3beta-hydroxysteroid dehydrogenase-2, and steroid acute regulatory protein were expressed at modest levels in all tissues examined in both mouse and human. In failing human heart, CYP11B1 and CYP11B2 were detected in some samples, in contrast with normal hearts, which expressed neither; in the mouse heart steroidogenic factor-1 was detected, but neither CYP11B1 nor CYP11B2 was found. Steroidogenic factor-1 was detected in no human heart sample tested after 40 cycles of PCR. Although the expression of some steroidogenic genes can be detected in the heart, the likelihood of physiologically relevant levels of aldosterone production by the normal heart is very low. The exact cellular location of steroid synthesis in the failing human heart remains to be established.