Structural insights into UbiD reversible decarboxylation.

The ubiquitous UbiX-UbiD system is associated with a wide range of microbial (de)carboxylation reactions. Recent X-ray crystallographic studies have contributed to elucidating the enigmatic mechanism underpinning the conversion of α,ß-unsaturated acids by this system. The UbiD component utilises a unique cofactor, prenylated flavin (prFMN), generated by the bespoke action of the associated UbiX flavin prenyltransferase. Structure determination of a range of UbiX/UbiD representatives has revealed a generic mode of action for both the flavin-to-prFMN metamorphosis and the (de)carboxylation. In contrast to the conserved UbiX, the UbiD superfamily is associated with a versatile substrate range. The latter is reflected in the considerable variety of UbiD quaternary structure, dynamic behaviour and active site architecture. Directed evolution of UbiD enzymes has taken advantage of this apparent malleability to generate new variants supporting in vivo hydrocarbon production. Other applications include coupling UbiD to carboxylic acid reductase to convert alkenes into α,ß-unsaturated aldehydes via enzymatic CO2 fixation.

Enzymatic N-Allylation of Primary and Secondary Amines Using Renewable Cinnamic Acids Enabled by Bacterial Reductive Aminases.

Allylic amines are a versatile class of synthetic precursors of many valuable nitrogen-containing organic compounds, including pharmaceuticals. Enzymatic allylic amination methods provide a sustainable route to these compounds but are often restricted to allylic primary amines. We report a biocatalytic system for the reductive N-allylation of primary and secondary amines, using biomass-derivable cinnamic acids. The two-step one-pot system comprises an initial carboxylate reduction step catalyzed by a carboxylic acid reductase to generate the corresponding α,ß-unsaturated aldehyde in situ. This is followed by reductive amination of the aldehyde catalyzed by a bacterial reductive aminase pIR23 or BacRedAm to yield the corresponding allylic amine. We exploited pIR23, a prototype bacterial reductive aminase, self-sufficient in catalyzing formal reductive amination of α,ß-unsaturated aldehydes with various amines, generating a broad range of secondary and tertiary amines accessed in up to 94% conversion under mild reaction conditions. Analysis of products isolated from preparative reactions demonstrated that only selective hydrogenation of the C=N bond had occurred, preserving the adjacent alkene moiety. This process represents an environmentally benign and sustainable approach for the synthesis of secondary and tertiary allylic amine frameworks, using renewable allylating reagents and avoiding harsh reaction conditions. The selectivity of the system ensures that bis-allylation of the alkylamines and (over)reduction of the alkene moiety are avoided.

Synthetic Enzyme-Catalyzed CO2 Fixation Reactions.

In recent years, (de)carboxylases that catalyze reversible (de)carboxylation have been targeted for application as carboxylation catalysts. This has led to the development of proof-of-concept (bio)synthetic CO2 fixation routes for chemical production. However, further progress towards industrial application has been hampered by the thermodynamic constraint that accompanies fixing CO2 to organic molecules. In this Review, biocatalytic carboxylation methods are discussed with emphases on the diverse strategies devised to alleviate the inherent thermodynamic constraints and their application in synthetic CO2 -fixation cascades.

Sustaining a Focus on Health Equity at the Centers for Disease Control and Prevention Through Organizational Structures and Functions.

The public health infrastructure required for achieving health equity is multidimensional and complex. The infrastructure should be responsive to current and emerging priorities and capable of providing the foundation for developing, planning, implementing, and evaluating health initiatives. This article discusses these infrastructure requirements by examining how they are operationalized in the organizational infrastructure for promoting health equity at the Centers for Disease Control and Prevention, utilizing the nation's premier public health agency as a lens. Examples from the history of the Centers for Disease Control and Prevention's work in health equity from its centers, institute, and offices are provided to identify those structures and functions that are critical to achieving health equity. Challenges and facilitators to sustaining a health equity organizational infrastructure, as gleaned from the Centers for Disease Control and Prevention's experience, are noted. Finally, we provide additional considerations for expanding and sustaining a health equity infrastructure, which the authors hope will serve as "food for thought" for practitioners in state, tribal, or local health departments, community-based organizations, or nongovernmental organizations striving to create or maintain an impactful infrastructure to achieve health equity.

Cyclodextrin-hydrophobe complexation in associative polymers.

We develop a new rheology-based method to study the complexation of cyclodextrins with hydrophobes in hydrophobically modified associative polymer solutions. The associative polymers have comb-like structure with hydrophobic groups randomly attached to the polymer backbone. Intermolecular interactions between the hydrophobic groups form a transient network resulting in thickening of the polymer solutions. On addition of cyclodextrins (CD) to the solution, the hydrophobes are encapsulated within the hydrophobic cavity of the cyclodextrins. This reduces viscoelastic properties of the polymer solution by several orders of magnitude. We exploit the existence of a dynamic equilibrium between CD adsorbed to the hydrophobes and free CD in the solution, to develop a rheology-based Langmuir-type adsorption isotherm for estimating the binding constant for molecular complexation. The model is based on the assumption that the amount of CD adsorbed is proportional to the reduction in elastic modulus of the polymer solution due to the encapsulation of the network junctions by CD. The effects of temperature on binding constant are studied to estimate the enthalpy and entropy of complexation. Experiments are conducted with both α-and ß-CD at different polymer concentrations and temperatures to estimate the relative strength of binding of the CDs. At a given temperature and a polymer concentration, α-CD has a lower binding constant compared to that of ß-CD, indicating higher affinity of α-CD to adsorb onto the hydrophobes. Since α-CDs have a smaller ring size, they can snugly fit to the hydrophobes and the association leads to higher enthalpy and entropy change.

Kinetics of enzymatic depolymerization of guar galactomannan.

A new mathematical model based on Michaelis Menten (MM) kinetics is developed to predict the changes in molecular weight distribution (MWD) during the enzymatic depolymerization of guar galactomannan. The model accounts for the effect of branching by considering the guar molecule as a substrate having three types of bonds with different MM kinetic parameters. The overall kinetics of the enzymatic reactions then can be represented in terms of composite kinetic parameters that are functions of the MM parameters for the individual bonds. The depolymerization is assumed to follow a random scission mechanism, in which an enzyme randomly attacks the substrate molecule at any one of the three types of bonds, and leaves the substrate on cleavage of the bond. Expressions for the variation in molecular weights during depolymerization are developed by applying moment generating techniques to the kinetic model. The model is evaluated against the complete MWD obtained using gel permeation chromatography. During the initial stages of depolymerization, the enzymatic reaction is in the zero-order regime of MM kinetics and the polydispersity index (PDI) increases with time. Subsequently, the PDI decreases as the depolymerization tends to follow first order kinetics. We also show that for a zero-order, random or nonrandom scission, the variation of PDI with time can exhibit a maximum. These analyses confirm that an increase in PDI during the depolymerization is not necessarily due to nonrandom scission, as previously concluded.

Knowledge and use of birth control in Barbados

Based on material collected in Barbados in 1964, this paper examines knowledge and use of birth control in terms of 3 types of family union - married, common law, and visiting. Analysis of knowledge of birth control is dealt with for the sample at large, for educational attainment, and for the average number of methods known by each woman. The relative importance of the different methods known is also treated by family type and education. The extent to which women in the sample make use of birth control is discussed from 4 aspects. First, the growing use of the different methods among younger-age cohorts is made evident from tabulations of methods-last used. Second, information on the agencies and individuals recommending the use of different contraceptives emphasizes the degree to which the partner's influence is responsible for resort to birth control. Third, the proportions of users in religious groups show that religion is not a barrier to the use of any method. Fourth, the material is treated from the standpoint of age cohorts, since there is, in many cases, a vagueness as to the age at which use began, although women are able to identify the inter-pregnancy period when use began

A gross mating table for a West Indian population

At a sample survey carried out in Trinidad in 1958 data were collected on the participation of women in three union types: "visiting", "common law" and "married". It is assumed that the maximum number of changes of union type in which a woman is involved is three. From the survey material the chances of non-East Indian women moving from one type of union to another as they pass through the childbearing span (taken here as 14 to 45) are calculated. These chances are used to construct a table showing the types of unions in which a cohort of 10 000 women are involved between ages 14 to 45. This table makes possible the estimation of the length of time spent by the average woman in the three union types as well as the time spent in the "single" state, the numbers of women participating in these union types at different ages and the stability of these types of union. This table emphasizes that despite the fact that the "visiting" type is very important at lower ages, there is a progressive concentration in "married and "common law" types with advance in age, and by age 45 more than half the women are "married" and about one-fifth are in "common law" associations. It also shows that the average woman spends the longest period of childbearing life in the "married" state (9.6 years), the shortest time in "visiting" unions (4.1 years) and 5.9 years in "common law" unions. Stability is strongest in the case of the "married" type and lowest for the "visiting"; this, however, may be viewed not so much as evidence of family disorganization, but as a progressive shift from a less stable to a more stable union type. (Summary)

An analysis of West Indian mortality under 5 years (abstract only)

This paper analyses movements in cohort mortalities under 5 for Trinidad and Jamaica over the period 1901-51. This half century is divided into three parts: 1901-20, characterised by high and generally unchanging mortality; 1921-41, characterized by marked declines in mortality; 1942-51, characterised by continued improvements in mortality. It is shown that declines commenced in aged 2-4 rather than in infant mortality, where improvements were slow to emerge. Moreover rates of decline continued to be greater for the age range 1-4 during the years of increasing mortality control ushered in after 1921. The latest data still show that declines in mortalities control over age 1 continue to exceed those in infancy. For 1942-51 rates of decline for Trinidad 4ql values amount to 3.8 per cent (males) and 1.5 per cent (females), as compared with rates of 1.3 per cent and 1.5 per cent respectively for Qo. The rates studied can be utilised as simple approaches to three problems of mortality. They lend some support to the hypothesis that a cohort tends to be affected throughout its life span by it initial mortality. The hypothesis that high infant mortality tends to be followed by comparatively low rates at ages over 1 is not subtantiated for the period of rapid mortality decline (1921-41), though it is supported for the years 1901-20 when there was virtually no control of death rates. To the third problem raised - whether cohort mortalities tend to be more strongly associated than calendar year mortalities - the simple approaches adopted here permit only tentative answers (AU)

Some aspects of mating and fertility in the West Indies

This paper deals with certain problems in fertility analysis in the West Indies that have their origin in 2 characteristics of the populations involved: the diversity of family forms and the imbalance between the sexes. Considerations of the main features of these family types, in terms of a fourfold classification as well as in terms of the threefold classification adopted at recent censuses (single, common law and married), show that many techniques relied on in the study of fertility among European populations are inapplicable to West Indian populations. The limited data available permit only rough estimates of the rates of formation of different types of unions: but these emphasize that formal marriage usually takes place late in the childbearing period, generally after the couple has had one or more children, that the formation of keeper unions begins considerably earlier and that the common law type is a transitional state between the looser keeper union and the state of marriage. There seems to be no chance of studying fertility differentials among the several family types in terms of reproduction rates. Census data however provide 3 measures for this purpose, all of which show that fertility is highest for the married type and lowest for the single or keeper union. These differentials seem to run counter to the more usual pattern of fertility differential which show fertility lowest among groups of high socio-economic standing. Imbalance between the sexes is of importance primarily in the problem of arriving at satisfactory indices of fertility, though it may also have contributed somewhat to the establishment of the pattern of low marriage rates. Wide discrepancies between rates based on males and rates based on females appear, both in respect of fertility levels at given points of time and in respect of fertility trends. These discrepancies seem closely related to the imbalance between the sexes in the reproductive age span. Under these conditions the use of joint G.R.R's clearly offers a more realistic measure of fertility than rates based on either sex (SUMMARY)