Influence of modifying agents on enzyme inactivation studies. An analysis using a series mechanism and a form of the Hill-type equations

A series deactivation model is utilized to theoretically examine the influence of different modifying agents on enzyme deactivation kinetics. A form of the Hill-type equation is used to describe the effect of the modifying agents on the model parameters. Modification-induced inactivation equations are presented for the acetylation and succinylation of E. Coli asparaginase, for the site-specific reagent and substrate modification of flavocytochrome b(2) from Baker's yeast, and for the guanidinium chloride inactivation of cathepsin D. The analysis of more data for these and other enzymes would help further substantiate the technique presented and enhance the applicability of the model.     

Categorization of enzyme deactivations using a series-type mechanism

A series-type enzyme deactivation model involving an active enzyme precursor and a final enzyme state with possible non-zero activity is proposed to categorize enzyme deactivation curves. The enzyme activity is a weighted function of the active enzyme states. The deactivation curves may be broadly classified into two major categories wherein the activity is either always less than or it may be more than the initial activity for some time period. Data taken from the literature may be classified into 14 cases. Complex enzyme deactivation curves exhibiting enzyme stabilization and a flex are some of the features that are classified.     

Partial Deletion of both the Spermine Synthase Gene and thePexGene in the X-linked Hypophosphatemic, Gyro (Gy) Mouse

Gy, along withHyp, is a dominant mutation of the normal genePexcausing X-linked hypophosphatemia in the mouse. HemizygousGymale mice, however, have greater defects in survival, bodily growth, skeletal mineralization, and neurological function than those found in heterozygousGyfemales or inHypmice. Since the gene for spermine synthase is immediately upstream of the homologous human genePEX, we compared the effects of theGyandHypmutations on both the spermine synthase gene and thePexgene. Barely detectable levels of spermine (<5 % of normal) with elevated levels of its precursor, spermidine, were found in organs ofGymale mice compared to normal male littermates. NeitherGyfemales norHypmale mice were significantly affected. Four missing introns of the spermine synthase gene were identified inGymale mice, suggesting extensive gene disruption. A pseudogene for spermine synthase was also identified in the mouse genome.PexmRNA was found in several but not all tissues studied in adult normal mice.PexmRNA was altered in bothGyandHypmice. All maleHypmice were lacking the 3′ end of thePexmessage, whereas all maleGymice were deficient at the 5′ end. In summary, theGymutation is associated with a recessively expressed mutation of the spermine synthase gene, leading to spermine deficiency, and a dominantly expressed mutation of thePexgene, leading to hypophosphatemia. Alterations in two contiguous genes inGymay explain the additional phenotypic abnormalities present in theGymale mouse.     

Utilization of diversity indices in evaluating the effect of a paper mill effluent on bottom fauna

Hydrobiologia - Bottom fauna surveys of the Lower Sabine River in the vicinity of Orange, Texas were performed from 1967 to 1969. During this time samples were taken before and after effluent from...     

The diet of the Wandering Albatross Diomedea exulans at Subantarctic Marion Island

Summary The diet of the Wandering Albatross at Subantarctic Marion Island was studied by inducing recently fed chicks to regurgitate and by stomach flushing adults about to feed chicks. Liquid comprised 70.2% of stomach content mass recovered from chicks. Solid material comprised cephalopods (58.6% by mass), fish (36.5%) and crustacean, cetacean and seabird material as minor items. Twenty-three taxa of cephalopods were identified, the onychcteuthid squid Kondakovia longimana being the most important. Estimated average mass of squid was 694 g with a maximum of over 8 kg. Diet of the Wandering Albatross at Marion Island was broadly similar to that at other studied localities. The high proportion of cephalopods known to float after death in the diet, and the deep-water habits of the few fish identified, suggest that scavenging plays an important role in foraging behaviour.     

Cyanobacterial Diversity and Halotolerance in a Variable Hypersaline Environment

The Great Salt Plains (GSP) in north-central Oklahoma, USA is an expansive salt flat (∼65 km²) that is part of the federally protected Salt Plains National Wildlife Refuge. The GSP serves as an ideal environment to study the microbial diversity of a terrestrial, hypersaline system that experiences wide fluctuations in freshwater influx and diel temperature. Our study assessed cyanobacterial diversity at the GSP by focusing on the taxonomic and physiological diversity of GSP isolates, and the 16S rRNA phylogenetic diversity of isolates and environmental clones from three sites (north, central, and south). Taxonomic diversity of isolates was limited to a few genera (mostly Phormidium and Geitlerinema), but physiological diversity based on halotolerance ranges was strikingly more diverse, even between strains of the same phylotype. The phylogenetic tree revealed diversity that spanned a number of cyanobacterial lineages, although diversity at each site was dominated by only a few phylotypes. Unlike other hypersaline systems, a number of environmental clones from the GSP were members of the heterocystous lineage. Although a number of cyanobacterial isolates were close matches with prevalent environmental clones, it is not certain if these clones reflect the same halotolerance ranges of their matching isolates. This caveat is based on the notable disparities we found between strains of the same phylotype and their inherent halotolerance. Our findings support the hypothesis that variable or poikilotrophic environments promote diversification, and in particular, select for variation in ecotype more than phylotype.     

Osteopathic manipulative treatment and its relationship to autonomic nervous system activity as demonstrated by heart rate variability: a repeated measures study

Background

Osteopathic manipulative treatment (OMT) and ultrasound physical therapy (UPT) are commonly used for chronic low back pain. Although there is evidence from a systematic review and meta-analysis that OMT generally reduces low back pain, there are no large clinical trials that specifically assess OMT efficacy in chronic low back pain. Similarly, there is a lack of evidence involving UPT for chronic low back pain.

Methods

The OSTEOPAThic Health outcomes In Chronic low back pain (OSTEOPATHIC) Trial is a Phase III randomized controlled trial that seeks to study 488 subjects between August 2006 and June 2010. It uses a 2 × 2 factorial design to independently assess the efficacy of OMT and UPT for chronic low back pain. The primary outcome is a visual analogue scale score for pain. Secondary outcomes include back-specific functioning, generic health, work disability, and satisfaction with back care.

Conclusion

This randomized controlled trial will potentially be the largest involving OMT. It will provide long awaited data on the efficacy of OMT and UPT for chronic low back pain.

Trial registration

http://www.clinicaltrials.gov, NCT00315120     

Pharmacology and Regional Distribution of the Binding of 6-[3H]Nitro-7-Sulphamoylbenzo[f]-Quinoxaline-2,3-Dione to Rat Brain

Abstract: 6-Nitro-7-sulphamoylbenzo[ f ]quinoxaline-2,3-dione (NBQX) is a competitive antagonist selective for α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors. Here we report the pharmacological characteristics and anatomical distribution of [³H]NBQX binding to rat brain. The association rate of [³H]NBQX to rat cerebrocortical membranes was rapid, with peak binding occurring within 10 min at 0°C. The off-rate was also rapid, with near-complete dissociation of the radioligand within 5 min of addition of 1 m M unlabelled l -glutamate. [³H]NBQX bound to a single class of sites with K _D and B _max values of 47 n M and 2.6 pmol mg⁻¹ of protein, respectively. The rank order of inhibition of [³H]NBQX binding by AMPA receptor ligands was NBQX ≫ 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) ≥ ( S )-5-fluorowillardiine ≥ AMPA ≫ l -glutamate. The chaotrope KSCN had no effect on the IC₅₀ value of unlabelled NBQX displacement of [³H]NBQX binding. The kainate receptor-selective ligands NS102 and kainate were only very weak displacers. It is interesting that NBQX and CNQX displaced significantly more [³H]NBQX than any of the agonists tested. Autoradiographic analysis of the binding of [³H]NBQX to coronal sections showed a distribution compatible with that of [³H]AMPA binding. These data indicate that [³H]NBQX provides a useful novel tool to characterise the antagonist binding properties of AMPA receptors.     

From Documentation to Representation: Recovering the Films of Margaret Mead and Gregory Bateson

Although the seven films made by Margaret Mead and Gregory Bateson, based on footage shot in Bali and New Guinea during 1936–39, are identified as a landmark in various histories of ethnographic film, these films have been the subject of remarkably little analysis in the anthropological literature. In contrast, their photographic work has received much more extended commentary. Making a close reading of the films in their final edited form, this article aims to recover this aspect of Mead and Bateson's work from its relative neglect. We consider the circumstances under which the films were made, the theoretical ideas that informed them, and the methods employed in shooting and editing. Notwithstanding recent skepticism about both the theoretical ideas and the quality of the research on which Mead and Bateson's work in Bali was based, as well as the naiveté of some of the filmmaking ideas found in the films themselves, when considered as a group, they continue to be interesting examples of a particular transitional phase in the history of ethnographic film.