Phase behavior of ultrasoft spheres show stable bcc lattices.

The phase behavior of supersoft spheres is explored using solutions of ultralow cross-linked poly(N-isopropylacrylamide)-based microgels as a model system. For these microgels, the effects of the electric charges on their surfaces can be neglected and therefore only the role of softness on the phase behavior is investigated. The samples show a liquid-to-crystal transition at higher volume fraction with respect to both hard spheres and stiffer microgels. Furthermore, stable body centered cubic (bcc) crystals are observed in addition to the expected face centered cubic (fcc) crystals. Small-angle x-ray and neutron scattering with contrast variation allow the characterization of both the microgel-to-microgel distance and the architecture of single microgels in crowded solutions. The measurements reveal that the stable bcc crystals depend on the interplay between the collapse and the interpenetration of the external shell of the ultralow cross-linked microgels.

Lithium influences differentiation and tissue-specific gene expression of mouse embryonic stem (ES) cells in vitro.

The effects of lithium chloride (LiCl) on differentiation of mouse embryonic stem (ES) cells were investigated in order to evaluate the ES cell test (EST) used in a European Union validation study for screening of embryotoxic agents in vitro. We show that LiCl inhibited concentration-dependently the differentiation of ES cells into cardiac and myogenic cells. Whereas the inhibition of cardiac differentiation by high concentrations of LiCl was obvious at day 5 + 5, decreased skeletal muscle cell differentiation was observed only at day 5 + 8. Semi-quantitative RT-PCR analyses revealed significantly lower levels of mRNA encoding cardiac-specific alpha-myosin heavy chain and skeletal muscle-specific myoD. By morphological investigation, an influence of lithium on neuronal differentiation was not evident. However, mRNA levels of genes encoding synaptophysin and the 160 kDa neurofilament protein were increased by high LiCl concentrations, whereas mRNA levels of mash-1 and Engrailed-1 were decreased, suggesting a specific influence of lithium on neuronal differentiation. Furthermore, LiCl treatment resulted in a slight, but non-significant increase of beta-catenin levels in ES cell-derived embryoid bodies. Our results demonstrate that the ES cell test, EST may be suitable to detect inhibitory effects of test compounds especially on cardiac differentiation, whereas effects on neuronal cells would not be detected. Therefore, we propose that morphological analyses of cardiac differentiation alone are insufficient to detect embryotoxic effects. The assay of other cell lineages at different developmental stages, and expression analyses of tissue-specific genes should also be employed.

Interaction of MyoD family proteins with enhancers of acetylcholine receptor subunit genes in vivo.

The myogenic determination factors (MDFs) are transcriptional activators that target E boxes in many muscle-specific promoters, including those of the genes coding for the subunits of the acetylcholine receptor. It is not known, however, if in vivo a given E box in a transcriptionally active gene is occupied, either uniquely by one MDF or randomly by all MDFs. We have analyzed expression of MDF and acetylcholine receptor subunits in cultured mouse muscle cells and, using chromatin immunoprecipitation, have determined which individual MDFs reside at promoters of several receptor subunit genes. We find that before fusion, C2C12 cells express myf-5, MyoD, and myogenin, all of which take up residence at promoters of all subunits except epsilon. At this stage, herculin is present in limited amounts and is detected mainly at the gamma and delta subunit genes. On myotube formation, herculin reaches high levels; concomitantly, the epsilon subunit gene becomes a common MDF target and begins to be expressed. In general, any MDF protein that is expressed also is present on transcriptionally active receptor genes; transcriptional activity of target genes correlates with occupancy by MDF, in particular, herculin.

Neither aider nor abettor be: attorneys become prosecutorial targets for federal healthcare crimes.

Attorneys representing healthcare entities are not immune to federal criminal prosecution for the assistance that they give their clients. This Article focuses on potential attorney liability for aiding and abetting a client's violation of law. The author examines the securities, tax, and white-collar crime fields for guidance regarding the interpretation and application of the federal aiding and abetting statute to attorneys practicing in the health law field. Based on these analogous areas, and upon the federal criminal statutes applicable in the healthcare field, he recommends steps that can be taken to minimize the possibility of aiding and abetting liability. In addition, he recommends that the courts require a prosecutorial showing of both actual knowledge of wrong-doing and wrongful intent before imposing aider and abettor liability upon health law practitioners.

Identification of surrogate agonists for the human FPRL-1 receptor by autocrine selection in yeast.

We describe a procedure for isolating agonists for mammalian G protein-coupled receptors of unknown function. Human formyl peptide receptor like-1 (FPRL-1) receptor, originally identified as an orphan G protein-coupled receptor related to the formyl peptide receptor (FPR1), was expressed in Saccharomyces cells designed to couple receptor activation to histidine prototrophy. Selection for histidine prototrophs among transformants obtained with a plasmid-based library encoding random peptides identified six different agonists, each of whose production yielded autocrine stimulation of the receptor expressed in yeast. A synthetic version of each peptide promoted activation of FPRL-1 expressed in human embryonic kidney (HEK293) cells, and five of the peptides exhibited significant selectivity for activation of FPRL-1 relative to FPR1. One selective peptide was tested and found to mobilize calcium in isolated human neutrophils. This demonstrates that stimulation of FPRL-1 results in neutrophil activation and suggests that the receptor functions as a component of the inflammatory response. This autocrine selection protocol may be a generally applicable method for providing pharmacological tools to evaluate the physiological roles of the growing number of mammalian orphan G protein-coupled receptors.

Evaluation of nature-nurture impact on reproductive health using half-siblings.

Research in the field of preventive medicine will increasingly focus on the role of genetic susceptibility in disease etiology. Epidemiology plays an important role in identifying which diseases are good candidates for such research activity. Computerized population registries of unstable partner relationships and change in environmental exposure settings may provide new tools for research. We illustrate these tools using facial cleft defects as an example. The design is based upon computerized and stored data from large population samples. Data on change of partner or environment between births are used to learn about the recurrence risks for diseases that were present in their first child. The study focused on a susceptible subgroup of the population who previously had an affected child. Thus, by definition, these couples had a sufficient set of causes to initiate the disease and an increased risk of recurrence if relevant genetic or environmental factors remained unchanged. When considering recurrence risks after changes in possible genetic or nongenetic risk factors, etiologically important clues may emerge. The example confirms that genetic factors play a major role in facial cleft defects.

[Risk of the recurrence of cleft lip and palate after changing of partner or residence]. / Gentagelsesrisiko for laebe-ganespalte efter partner- eller adresseskift.

The aim of the present study was to determine the effect of changing residence on recurrence of congenital facial cleft defects. We identified 4189 women that had given birth to infants with a facial cleft detect by linking a database comprising facial cleft cases born between 1952 and 1987 with the Central Person Registry in Denmark. Changing municipality did not decrease the frequency of recurrence of facial cleft defects in later-born sibs. Among the 907 infants of mothers who changed municipality but not partner, 29 (3.2 percent) had a facial cleft defect, as compared with 48 (3.4 percent) of 1425 infants of mothers who changed neither municipality nor partner. However, change of partner significantly reduced the recurrence risk. Among 236 infants of mothers who changed partners, 1 (0.4 percent) had a facial cleft defect, as compared with 77 (3.3 percent) of 2350 infants of mothers who did not change partners. Recurrence of facial cleft defects is not linked to the residence of the mother, but having a different partner reduced the woman's risk of having a second infant with this defect.

The effects of interference on verbal learning in multiple sclerosis.

Thirty multiple sclerosis (MS) patients were compared with 30 matched (age and education) controls and were asked to learn and recall 20 target words that were placed among 24 distracter words. Targets and distracters were printed on different colored cards, and the subjects were asked to read each word aloud and recall the target words. This task was repeated four times. The MS patients recalled significantly fewer words across the four trials. A second list without distracters was presented for two trials, and there were no significant differences between the groups' recall. Subsequent recall (short delay and long delay) for List 1 revealed significantly poorer recall for the MS group and significantly poorer cued recall but not recognition memory. Retrieval processes were implicated such as source memory, or contextual stamping, rather than encoding mechanisms.

Absence of an environmental effect on the recurrence of facial-cleft defects.

BACKGROUND: The rate of recurrence of a broad range of birth defects may decrease among women who change residence after the birth of their first infant. The aim of the present study was to determine the effect of changing residence on the recurrence of congenital facial-cleft defects. METHODS: We identified 4189 women who had infants with facial-cleft defects by linking a data base comprising the records of children with facial clefts born between 1952 and 1987 with the Central Person Registry in Denmark. Among the 4189 mothers, 1902 each had additional children after the first child with a facial-cleft defect. A total of 2692 younger siblings were identified. We compared the proportion of infants with facial-cleft defects among the younger siblings between mothers who had changed municipalities or sexual partners and those who had not. RESULTS: Changing the municipality of residence did not decrease the frequency with which facial-cleft defects recurred in younger siblings. Among the 907 infants of mothers who changed municipalities but not partners, 29 (3.2 percent) had facial-cleft defects, as compared with 48 (3.4 percent) of 1425 infants of mothers who changed neither municipality nor partner (relative risk, 0.9; 95 percent confidence interval, 0.6 to 1.5). However, a change of partner reduced the recurrence risk significantly. Among 236 infants of mothers who changed partners, 1 (0.4 percent) had a facial-cleft defect, as compared with 77 (3.3 percent) of 2350 infants of mothers who did not change partners (relative risk, 0.1; 95 percent confidence interval, 0.02 to 0.9). CONCLUSIONS: Recurrence of facial-cleft defects is not linked to the residence of the mother, but having a different partner reduced a woman's risk of having a second child with this defect.

Depolarization-transcription signals in skeletal muscle use calcium flux through L channels, but bypass the sarcoplasmic reticulum.

Membrane depolarization inactivates acetylcholine receptor (AChR) genes in skeletal muscle. We have studied this process in C2C12 cells, focusing on the role of calcium. Cytoplasmic calcium was monitored with fluo-3, and the activity of receptor genes was measured with a sensitive transcript elongation assay. Removal of extracellular calcium or blockage of L-type calcium channels disrupts signaling, even when release of calcium from the sarcoplasmic reticulum (SR) is not impeded, whereas L channel agonists induce signaling without membrane depolarization or release of calcium from intracellular stores. Activators of calcium release from the SR do not inhibit AChR genes, either in C2C12 or in chicken skeletal muscle in vivo. It appears that calcium ions do not act as messengers between sarcolemma and nucleus but target a sensor near their port of entry where they initiate a signal that bypasses the SR.

Rapid inhibition of myogenin-driven acetylcholine receptor subunit gene transcription.

In investigating the coupling of depolarization and transcription in skeletal muscle we have focused on how protein kinase C suppresses acetylcholine receptor subunit genes. The activity of acetylcholine receptor subunit promoters in non-muscle cells co-transfected with myogenic factors and E proteins was measured, and their response to protein kinase C activation analyzed. To simplify interpretation of results, gene activities rather than levels of reporter enzymes were assayed, transcriptional effects of phorbol esters were determined, with drug exposures brief enough to preclude kinase depletion, and analysis was carried out with HeLa cells, which are not liable to myogenic conversion. Myogenin, which had been postulated previously to play a role in denervation supersensitivity (Neville et al., Mol. Cell. Neurobiol., 12, 511-527, 1992), was found to be the only myogenic factor whose inactivation kinetics can account for the plasma membrane-protein kinase C-receptor gene cascade observed in intact muscle (Huang et al., Neuron, 9, 671-678, 1992).

Mammalian sex chromosomes: design or accident?

Mammalian sex chromosomes evolved (and are still evolving) from a homomorphic pair by the progressive loss of active genes from the Y chromosome. Among the changes that have accompanied this differentiation, it is difficult to determine causes, effects and correlates. Comparative studies suggest that the choice of a gene, and thus a chromosome pair, to control the sex-determining pathway may be quite arbitrary, and that sex chromosomes and sex-determining genes are more likely to be the products of random changes than the products of selection for function.

Amount of therapist contact and outcome in a multidimensional depression treatment program.

An 8-week multidimensional program of behavioral management, cognitive restructuring, and assertiveness training was administered to depressed outpatients either individually with a single therapist (n = 12), in two small groups (n = 11), or one large group (n = 11), or as bibliotherapy (n = 12). A randomly assigned waiting list control group was also included (n = 10). Follow-up assessments were conducted at 18 weeks. Principal findings were that 1) there were no significant pretreatment differences among groups, 2) all treated groups including bibliotherapy improved substantially over the course of treatment, 3) the waiting list control group was unchanged during this same period, 4) there were no significant differences among treated groups at termination or at follow-up, nor did these groups change significantly over the period of follow-up. Thus the effectiveness of this multidimensional program was supported, but its efficacy was not systematically influenced by amount of therapist contact.