A high melting structure in DNA distinguishes phases of the cell cycle

Differential scanning microcalorimetry of the nuclei of dividing CHO cells revealed DNA structures that showed structural transitions at 60, 76, 88, and 105 degrees C (transitions I to IV, respectively). In cultures synchronized by isoleucine deprivation the enthalpies of transitions I and II were rather constant throughout the cell cycle. While the sum of the enthalpies of III and IV was nearly constant, the ratio of IV to III varied substantially from one phase of the cycle to another. A high IV:III ratio of 6 characterized G1 while S phase gave a IV:III ratio of about 2. Cells containing metaphase chromosomes also showed a IV:III ratio near 2. The IV:III ratio for CHO cells showed a progressive decrease as the cells were maintained in isoleucine-free medium from 0 to 6 days.     

Wendell Stanley's dream of a free-standing biochemistry department at the University of California, Berkeley

Conclusion Scientists and historians have often presumed that the divide between biochemistry and molecular biology is fundamentally epistemological.¹⁰⁰ The historiography of molecular biology as promulgated by Max Delbrück's phage disciples similarly emphasizes inherent differences between the archaic tradition of biochemistry and the approach of phage geneticists, the ur molecular biologists. A historical analysis of the development of both disciplines at Berkeley mitigates against accepting predestined differences, and underscores the similarities between the postwar development of biochemistry and the emergence of molecular biology as a university discipline. Stanley's image of postwar biochemistry, with its focus on viruses as key experimental systems, and its preference for following macromolecular structure over metabolism pathways, traced the outline of molecular biology in 1950.Changes in the postwar political economy of research universities enabled the proliferation of disciplines such as microbiology, biochemistry, biophysics, immunology, and molecular biology in universities rather than in medical schools and agricultural colleges. These disciplines were predominantly concerned with investigating life at the subcellular level-research that during the 1930s had often entailed collaboration with physicists and chemists. The interdisciplinary efforts of the 1930s (many fostered by the Rockefeller Foundation) yielded a host of new tools and reagents that were standardized and mass-produced for laboratories after World War II. This commercial infrastructure enabled basic researchers in biochemistry and molecular biology in the 1950s and 1960s to become more independent from physics and chemistry (although they were practicing a physicochemical biology), as well as from the agricultural and medical schools that had previously housed or sponsored such research. In turn, the disciplines increasingly required their practitioners to have specialized graduate training, rather than admitting interlopers from the physical sciences.These general transitions toward greater autonomy for biochemistry and allied disciplines should not mask the important particularities of these developments on each campus. At the University of Caliornia at Berkeley, agriculture had provided, with medicine, significant sponsorship for biochemistry. The proximity of Lawrence and his cyclotrons supported the early development of Berkeley as a center for the biological uses of radioisotopes, particularly in studies of metabolism and photosynthesis. Stanley arrived to establish his department and virus institute before large-scale federal funding of biomedical research was in place, and he courted the state of California for substantial backing by promising both national prominence in the life sciences and virus research pertinent to agriculture and public health. Stanley's venture benefited significantly from the expansion of California's economy after World War II, and his mobilization against viral diseases resonated with the concerns of the Cold War, which fueled the state's rapid growth. The scientific prominence of contemporary developments at Caltech and Stanford invites the historical examination of the significance of postwar biochemistry and molecular biology within the political and cultural economy of the Golden State.In 1950, Stanley presented a persuasive picture of the power of biochemistry to refurbish life science at Berkeley while answering fundamental questions about life and infection. In the words of one Rockefeller Foundation officer,There seems little doubt in [my] mind that as a personality Stanley will be well able to dominate the other personalities on the Berkeley campus and will be able to drive his dream through to completion, which, incidentally, leaves Dr. Hubert [sic] Evans and the whole ineffective Life Sciences building in the somewhat peculiar position of being by-passed by much of the truly modern biochemistry and biophysics research that will be carried out at Berkeley. Furthermore, it seems likely that Dr. S's show will throw Dr. John Lawrence's Biophysics Department strongly in the shade both figuratively and literally, but should make the University of California pre-eminent not only in physics but in biochemistry as well.¹⁰¹ Stanley, Sproul, Weaver, and this officer (William Loomis) all testified to a perceptible postwar opportunity to capitalize on public support for biological research that relied on the technologies from physics and chemistry without being captive to them, and that addressed issues of medicine and agriculture without being institutionally subservient. What is striking, given the expectation by many that Stanley would be able to drive his dream through to completion, was that in fact he did not. Biochemists who had succeeded in making their expertise valued in specialized niches were resistant to giving up their affiliations to joint Stanley's liberated organization. Stanley's failure was not simply due to institutional factors: researchers as well as Rockefeller Foundation officers faulted him for his lack of scientific imagination, which made it difficult for him to gain credibility in leading the field. Moreover, many biochemists did not share Stanley's commitment to viruses as the key material for the new biochemistry.In the end, Stanley's free-standing department did become a first-rate department of biochemistry, but only after freeing itself from Stanley's leadership and his single-minded devotion to viruses. Nonetheless, the falling-out with the Berkeley biochemists was rapidly followed by the establishment of a Department of Molecular Biology, attesting to the unabating economic and institutional possibilities for an authoritative general biology (or two, for that matter) to take hold. In each case, following Stanley's dream sheds light on how the possible and the real shaped the (re)formation of biochemistry and molecular biology as postwar life sciences.     

Association of the catalytic subunit of aspartate transcarbamoylase with a zinc-containing polypeptide fragment of the regulatory chain leads to increases in thermal stability.

The regulatory enzyme aspartate transcarbamoylase (ATCase), comprising 2 catalytic (C) trimers and 3 regulatory (R) dimers, owes its stability to the manifold interchain interactions among the 12 polypeptide chains. With the availability of a recombinant 70-amino acid zinc-containing polypeptide fragment of the regulatory chain of ATCase, it has become possible to analyze directly the interaction between catalytic and regulatory chains in a complex of simpler structure independent of other interactions such as those between the 2 C trimers, which also contribute to the stability of the holoenzyme. Also, the effect of the interaction between the polypeptide, termed the zinc domain, and the C trimer on the thermal stability and other properties can be measured directly. Differential scanning microcalorimetry experiments demonstrated that the binding of the zinc domain to the C trimer leads to a complex of markedly increased thermal stability. This was shown with a series of mutant forms of the C trimer, which themselves varied greatly in their temperature of denaturation due to single amino acid replacements. With some C trimers, for which tm varied over a range of 30 degrees C due to diverse amino acid substitutions, the elevation of tm resulting from the interaction with the zinc domain was as large as 18 degrees C. The values of tm for a variety of complexes of mutant C trimers and the wild-type zinc domain were similar to those observed when the holoenzymes containing the mutant C trimers were subjected to heat denaturation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Breast MRI in nonpalpable breast lesions: a randomized trial with diagnostic and therapeutic outcome – MONET – study

Background

In orthodontic treatment, anchorage control is a fundamental aspect. Usually conventional mechanism for orthodontic anchorage control can be either extraoral or intraoral that is headgear or intermaxillary elastics. Their use are combined with various side effects such as tipping of occlusal plane or undesirable movements of teeth. Especially in cases, where key-teeth are missing, conventional anchorage defined as tooth-borne anchorage will meet limitations. Therefore, the use of endosseous implants for anchorage purposes are increasingly used to achieve positional stability and maximum anchorage.

Methods/Design

The intended study is designed as a prospective, multicenter randomized controlled trial (RCT), comparing and contrasting the effect of early loading of palatal implant therapy versus implant loading after 12 weeks post implantation using the new ortho-implant type II anchor system device (Orthosystem Straumann, Basel, Switzerland). 124 participants, mainly adult males or females, whose diagnoses require temporary stationary implant-based anchorage treatment will be randomized 1:1 to one of two treatment groups: group 1 will receive a loading of implant standard therapy after a healing period of 12 week (gold standard), whereas group 2 will receive an early loading of orthodontic implants within 1 week after implant insertion. Participants will be at least followed for 12 months after implant placement. The primary endpoint is to investigate the behavior of early loaded palatal implants in order to find out if shorter healing periods might be justified to accelerate active orthodontic treatment. Secondary outcomes will focus e.g. on achievement of orthodontic treatment goals and quantity of direct implant-bone interface of removed bone specimens. As tertiary objective, a histologic and microtomography evaluation of all retrieved implants will be performed to obtain data on the performance of the SLA surface in human bone evaluation of all retrieved implants. Additionally, resonance frequency analysis (RFA, Osstell? mentor) will be used at different times for clinically monitoring the implant stability and for histological comparison in order to measure the reliability of the resonance frequency measuring device.

Trial registration

Current Controlled Trials ISRCTN97142521.     

Direct effect of ethanol on human vascular function

Epidemiological studies indicate that moderate ethanol consumption reduces cardiovascular mortality. Cellular and animal data suggest that ethanol confers beneficial effects on the vascular endothelium and increases the bioavailability of nitric oxide. The purpose of this study was to assess the effect of ethanol on endothelium-dependent, nitric oxide-mediated vasodilation in healthy human subjects. Forearm blood flow (FBF) was determined by venous occlusion plethysmography in healthy human subjects during intra-arterial infusions of either methacholine (0.3, 1.0, 3.0, and 10.0 mcg/min, n = 9), nitroprusside (0.3, 1.0, 3.0, and 10.0 mcg/min, n = 9), or verapamil (10, 30, 100, and 300 mcg/min, n = 8) before and during the concomitant intra-arterial infusions of ethanol (10% ethanol in 5% dextrose). Additionally, a time control experiment was conducted, during which the methacholine dose-response curve was measured twice during vehicle infusions (n = 5). During ethanol infusion, mean forearm and systemic alcohol levels were 227 +/- 30 and 6 +/- 0 mg/dl, respectively. Ethanol infusion alone reduced FBF (2.5 +/- 0.1 to 1.9 +/- 0.1 ml.dl(-1).min(-1), P < 0.05). Despite initial vasoconstriction, ethanol augmented the FBF dose-response curves to methacholine, nitroprusside, and verapamil (P < 0.01 by ANOVA for each). To determine whether this augmented FBF response was related to shear-stress-induced release of nitric oxide, FBF was measured during the coinfusion of ethanol and N(G)-nitro-L-arginine (L-NAME; n = 8) at rest and during verapamil-induced vasodilation. The addition of L-NAME did not block the ability of ethanol to augment verapamil-induced vasodilation. Ethanol has complex direct vascular effects, which include basal vasoconstriction as well as potentiation of both endothelium-dependent and -independent vasodilation. None of these effects appear to be mediated by an increase in nitric oxide bioavailability, thus disputing findings from preclinical models.     

Successful immunotherapy with matrix metalloproteinase-derived peptides in adjuvant arthritis depends on the timing of peptide administration

We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development of such therapies.     

Reliability of an injury scoring system for horses

Background

The risk of injuries is of major concern when keeping horses in groups and there is a need for a system to record external injuries in a standardised and simple way. The objective of this study, therefore, was to develop and validate a system for injury recording in horses and to test its reliability and feasibility under field conditions.

Methods

Injuries were classified into five categories according to severity. The scoring system was tested for intra- and inter-observer agreement as well as agreement with a 'golden standard' (diagnosis established by a veterinarian). The scoring was done by 43 agricultural students who classified 40 photographs presented to them twice in a random order, 10 days apart. Attribute agreement analysis was performed using Kendall's coefficient of concordance (Kendall's W), Kendall's correlation coefficient (Kendall's τ) and Fleiss' kappa. The system was also tested on a sample of 100 horses kept in groups where injury location was recorded as well.

Results

Intra-observer agreement showed Kendall's W ranging from 0.94 to 0.99 and 86% of observers had kappa values above 0.66 (substantial agreement). Inter-observer agreement had an overall Kendall's W of 0.91 and the mean kappa value was 0.59 (moderate). Agreement for all observers versus the 'golden standard' had Kendall's τ of 0.88 and the mean kappa value was 0.66 (substantial). The system was easy to use for trained persons under field conditions. Injuries of the more serious categories were not found in the field trial.

Conclusion

The proposed injury scoring system is easy to learn and use also for people without a veterinary education, it shows high reliability, and it is clinically useful. The injury scoring system could be a valuable tool in future clinical and epidemiological studies.

     

Diffusion is capable of translating anisotropic apoptosis initiation into a homogeneous execution of cell death

Background  

Apoptosis is an essential cell death process throughout the entire life span of all metazoans and its deregulation in humans has been implicated in many proliferative and degenerative diseases. Mitochondrial outer membrane permeabilisation (MOMP) and activation of effector caspases are key processes during apoptosis signalling. MOMP can be subject to spatial coordination in human cancer cells, resulting in intracellular waves of cytochrome-c release. To investigate the consequences of these spatial anisotropies in mitochondrial permeabilisation on subsequent effector caspase activation, we devised a mathematical reaction-diffusion model building on a set of partial differential equations.