Enzyme deactivation

Enzyme deactivation kinetics is often first-order. Different examples of first-order deactivation kinetics exhibited by different enzymes under a wide variety of conditions are presented. Examples of both soluble and immobilized enzymes are presented. The influence of different parameters, chemical modification of specific residues, inhibitors, inactivators, protecting agents, induced conformational changes by external agents, enzyme concentration, and different substrates on the first-order inactivation kinetics of different enzymes is analyzed. The different examples presented from a variety of different areas provides a judicious framework and collection demonstrating the wide applicability of first-order deactivation kinetics. Examples of reversible first-order deactivation kinetics and deactivation-disguise kinetics are also presented.Different mechanisms are also presented to model complex enzyme deactivations. The non-series type mechanisms are emphasized and these involve the substrate and chemical modifiers. Substrate-dependent deactivation rate expressions that are of "separable" and "non-separable" type are presented. Rate expressions involving time-dependent rate constants along with their corresponding mechanisms are presented. Examples of enzymes that exhibit a deactivation-free grace period are also given. An interesting case of enzyme inactivation is the loss of activity in the presence of an auto-decaying reagent. The method is presented by which the intrinsic inactivation rate constants may be obtained. Examples of pH-dependent enzyme inactivation are presented that may be modelled by a five-step (or a simplified two-step) mechanism, and also by a single-step mechanism involving residual activity for the final state. Appropriate examples of enzyme inactivation are presented in each case to highlight the different mechanisms involved.     

Studies on Subcellular Fractions Which Are Involved in Myelin Membrane Assembly: Isolation from Developing Mouse Brain and Characterization by Enzyme Markers, Electron Microscopy, and Electrophoresis

An extensive scheme for the subcellular fractionation of myelinating mouse brain is presented. Several centrifugation procedures for the separation of membranes involved in myelinogenesis are critically appraised, and guidelines for selection of centrifugation conditions are given. Characteristics of subcellular fractions are presented in the form of electron micrographs; also presented are distribution of RNA and protein; electrophoretic profiles of membrane proteins, and verification of the myelin-specific basic proteins, proteolipid protein, and glycoprotein by the immuno-electroblot technique; and the distribution of eight marker enzyme activities. Myelin-related membranes were found to differ both qualitatively and quantitatively in their complement of myelin-specific proteins. These myelin-containing fractions appear to represent different stages of myelination that coexist in developing mouse brain. These results provide the fundamental methodologies and background information for kinetic radioisotope analysis of intracellular events in the assembly of myelin presented in a companion article.     

Flow pattern and pressure drop in gas-liquid cocurrent downflow through packed beds

Correlations for pressure drop in gas-liquid cocurrent downflow through packed beds are presented, taking into cognizance the flow pattern of the phases and covering a wide range in experimental conditions. Criteria for flow regime discrimination are presented separately for low porosity and for high porosity packings.     

The hierarchical structure of metabolic networks and the construction of efficient metabolic simulators

Methods are presented for the efficient simulation of large scale metabolic networks based upon the hierarchical structure of such networks and the formation of steady-state aggregations. The methods are dynamic and result in a varying time scale which is always consonant with the response of the network. An algorithm for the generation of reduced equivalent networks is presented. Problems of accuracy and stability are discussed. Special methods such as cascading and telescoping are presented for speeding the solution of the steady-state aggregations.     

Weight–length relationships for 54 species of the Arade estuary, southern Portugal

Weight–length relationships (WLRs) are presented for 54 species sampled by several types of fishing gear between February 2004 and May 2007, in the Arade estuary (southern Portugal). WLRs for six species are presented for the first time.     

New Staphylinidae (Coleoptera) records with new collection data from New Brunswick, and an addition to the fauna of Quebec, Canada: Aleocharinae

Thirty-eight species of Aleocharinae are newly reported from New Brunswick, bringing the total number of species known from the province to 216. Thirty-one of these species are newly recorded for the Maritime provinces, and four of them, Phloeopora oregona Casey, Gyrophaena michigana Seevers, Gyrophaena wisconsinica Seevers, and Tomoglossa decora (Casey), are newly recorded for Canada. Tomoglossa constitutes a new generic record for Canada. Collection and habitat data for all these species are presented and discussed. Color habitus, median lobe of the aedeagus, and male tergite and sternite 8 images are presented for the first time for Phloeopora oregona, and references to illustrations are provided for all other species included in this paper. A color habitus image is presented for Tomoglossa decora.     

Analytical solutions for transient thermal behavior in biological systems

Analytical solutions are presented for transient heat conduction in biological media. General boundary conditions and internal sources varied in both spatial and time variables are considered, thus, solutions for many special cases can be obtained with ease from the general solutions presented in this analysis.     

Quantitation of immobilized proteins

A method for the quantitative determination of immobilized proteins based on the binding and subsequent elution of Coomassie Blue R is presented. Also presented is a method for the immobilization of proteins in solution by entrapment in polyacrylamide. These entrapped proteins are then available for use in the assay method presented. Other analytical procedures can also be performed on the entrapped proteins, either alone or in combination with the protein quantitation. The dye binding and elution method presented provides a sensitive and, in most applications, rapid method for the quantitative detection of immobilized proteins. Rather than immobilization being an obstacle to the assay method, this approach utilizes the advantages of immobilization for the removal of excess reagents. Application of this approach to several types of immobilized protein are presented.     

On the biomechanics of human shoulder complex--II. Passive resistive properties beyond the shoulder complex sinus

In multi-segmented total-human-body models the most difficult and the least successful modeling of a major articulating joint has been the shoulder complex because of the lack of appropriate biomechanical data as well as the anatomical complexity of the region. In this paper, quantitative results on the three-dimensional passive resistive properties beyond the voluntary shoulder complex sinus are presented by applying the methodology developed in part I. Constant-restoring-force(moment) contours are established for the shoulder complex and the numerical results are presented for the three subjects tested. In addition, functional expansions are presented for the voluntary and restoring force(moment) contours using spherical coordinates.     

Observations on the growth rate and development of some East African antelopes

Linear body measurements are presented for two dik-diks, two Uganda kob and three topi calves. Age-weight curves are presented for the dik-diks. Development of characteristics markings is recorded.     

Diagnosis of acute intoxications in critically ill patients: focus on biomarkers – part 2: markers for specific intoxications

Abstract

In medical intensive care units, acute intoxications contribute to a large proportion of all patients. Epidemiology and a basic overview on this topic were presented in part one. The purpose of this second part regarding toxicological biomarkers in the ICU setting focuses on specific poisons and toxins. Following the introduction of anion and osmol gap in part one, it’s relevance in toxic alcohols and other biomarkers for these poisonings are presented within this publication. Furthermore, the role of markers in the blood, urine and cerebrospinal fluid for several intoxications is evaluated. Specific details are presented, amongst others, for cardiovascular drug poisoning, paracetamol (acetaminophen), ethanol, pesticides, ricin and yew tree intoxications. Detailed biomarkers and therapeutic decision tools are shown for carbon monoxide (CO) and cyanide (CN^-) poisoning. Also, biomarkers in environmental toxicological situations such as mushroom poisoning and scorpion stings are presented.     

Hemispheric differences in visual recognition of two Kanji characters

The purpose of the present study was to examine hemispheric differences in visual recognition of two kanji letters. Kanji phrases and nonsense kanji letters were presented unilaterally to the left or right visual hemifield in thirty normal right-handed men by a tachistoscope. The experiments were separated into three conditions; the mixing tasks (ten phrases and ten sets of nonsense letters are presented by mixture), the phase task (twenty phrases are presented), and the nonsense letters task (twenty sets of nonsense letters are presented). Under all conditions, significant right visual hemifield superiorities for the accuracy of recognition of phrase and nonsense letters were observed.     

Preoperative positioning of the protruding premaxilla in the bilateral cleft lip patient

The rationale and technique for preoperative retraction of a protrusive premaxilla in the bilateral complete cleft lip and palate patient are presented. Two types of pinned intraoral appliances are presented that can expand the palatal shelves while retracting the premaxillary segment. Findings from lateral cephalometric x-ray studies of eight appliance patients and six control patients with bilateral clefts but no appliance treatment are presented at age 15. The data indicate that the cephalometric values at age 15 are within the normal range for most patients. Incisor angulation was quite varied among the subjects.     

The international movement of livestock

The purpose of this paper is to provide an overview of the international movement of livestock. The reasons for international movements of livestock are discussed. The factors involved in the international transfer of livestock and genetic material are presented. Statistics of animals, semen, and embryos exported from the United States for fiscal years 1981 and 1982 are presented. The principal countries involved in importing U.S. livestock are listed.     

Ligand: a versatile computerized approach for characterization of ligand-binding systems

An erythrocyte encapsulator dialyzer has been fabricated and tested for preparing large quantities of animal blood for encapsulation. Less than 25 min is required to dialyze 150 ml of erythrocytes for encapsulation. Data are presented showing ca 30% encapsulation of added substances for bovine, equine, and porcine erythrocytes. Encapsulation parameters such as osmolality and temperature are discussed. Data are presented on the encapsulation of the pesticide diflubenzuron in bovine erythrocytes.     

Degenerate T-cell recognition of peptides on MHC molecules creates large holes in the T-cell repertoire

The cellular immune system screens peptides presented by host cells on MHC molecules to assess if the cells are infected. In this study we examined whether the presented peptides contain enough information for a proper self/nonself assessment by comparing the presented human (self) and bacterial or viral (nonself) peptides on a large number of MHC molecules. For all MHC molecules tested, only a small fraction of the presented nonself peptides from 174 species of bacteria and 1000 viral proteomes ([Formula: see text]0.2%) is shown to be identical to a presented self peptide. Next, we use available data on T-cell receptor-peptide-MHC interactions to estimate how well T-cells distinguish between similar peptides. The recognition of a peptide-MHC by the T-cell receptor is flexible, and as a result, about one-third of the presented nonself peptides is expected to be indistinguishable (by T-cells) from presented self peptides. This suggests that T-cells are expected to remain tolerant for a large fraction of the presented nonself peptides, which provides an explanation for the "holes in the T-cell repertoire" that are found for a large fraction of foreign epitopes. Additionally, this overlap with self increases the need for efficient self tolerance, as many self-similar nonself peptides could initiate an autoimmune response. Degenerate recognition of peptide-MHC-I complexes by T-cells thus creates large and potentially dangerous overlaps between self and nonself.     

New Coleoptera records from New Brunswick, Canada: Cerambycidae

Five species of Cerambycidae, Acmaeops discoideus (Haldeman), Anelaphus villosus (Fabricius), Phymatodes species (CNC sp. n. #1), Sarosesthes fulminans (Fabricius), and Urgleptus signatus (LeConte) are newly recorded for New Brunswick, Canada. All but Acmaeops villosus are new to the Maritime provinces. Phymatodes testaceus (Linnaeus) is removed from the faunal list of the province as a result of mislabeled specimens, records of Phymatodes maculicollis LeConte are presented confirming the presence of this species in New Brunswick, and the first recent records ofNeospondylis upiformis (Mannerheim) are presented. Additional records are given for the recently recorded Phymatodes aereus (Newman), indicating a wider distribution in the province. Collection data, habitat data, and distribution maps are presented for each species.     

The Distribution of the Number of Maxima in a Cyclic Sequence

A simple statistical method is presented which tests for non-randomness in a cyclic sequence. The distribution of the statistic is tabulated for short sequences, and a large sample approximation is derived. Significant values of the statistic are given for sequences of length up to 52. Easily used computer programs to carry out appropriate calculations are presented.     

Epidemiological models for heterogeneous populations: proportionate mixing,parameter estimation,and immunization programs

Deterministic models are presented for epidemics which occur quickly and for long-term endemic diseases where births and deaths must be considered. Contact-rate matrices are formulated in terms of activity levels and subpopulation sizes by using a proportionate-mixing assumption. Methods are presented for estimating epidemic and endemic parameters in both homogeneous and heterogeneous populations. Other authors' approaches to contact-rate matrices and spatial heterogeneity are described. Three immunization programs are analyzed for a model of a spatially heterogeneous population and are compared in a “city and villages” example.     

The Distribution of the Number of Maxima in a Cyclic Sequence

A simple statistical method is presented which tests for non-randomness in a cyclic sequence. The distribution of the statistic is tabulated for short sequences, and a large sample approximation is derived. Significant values of the statistic are given for sequences of length up to 52. Easily used computer programs to carry out appropriate calculations are presented.