Chemistry (derived from alchemy) is the science of interactions between matter at or near the atomic scale. Such matter includes atoms and collections of atoms (such as molecules, crystals, and metals) that constitute materials encountered in everyday life. Chemistry deals with the composition and statistical properties of such structures, as well as their transformations and interactions. According to modern chemistry, the physical properties of materials are generally determined by their structure at the atomic scale. Chemistry is, along with physics, one of the most fundamental natural sciences.

Introduction

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Chemistry is often called the central science because it connects other sciences, such as physics, material science, nanotechnology, biology and geology. Chemistry encompasses many specific specialized sub-disciplines that often overlap with significant portions of other sciences. Sub-disciplines, however, are very specific to chemistry, for example, they allow the manufacturing and testing of stronger materials, the synthesis of pharmaceuticals to treat disease, and determination of the mechanisms behind life processes.

A fundamental component of chemistry is that matter is involved. Chemistry may involve the interaction of matter with matter, or, involve matter with non-material phenomena such as energy. Most central and traditional to chemistry is the interaction of one substance with another such as in a chemical reaction where one substance or substances is transformed into another. This may involve electromagnetic radiation (as in photochemistry) where a chemical reaction is driven by the stimulation of light energy. However the chemical reaction is only part of a larger field that also studies matter in other ways. Chemical spectroscopists for example study the interaction of light with matter often without any reaction occurring.

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Clinical Chemistry current issue

[Editorials] Identifying Duplicate Publications: Primum non Nocere
Rifai, N., Bossuyt, P. M., Bruns, D. E. Mon, 28 Apr 2008 00:00:00 -0000

[Editorials] Homocysteine and Folate Status in an Era of Folic Acid Fortification: Balancing Benefits, Risks, and B-vitamins
Ueland, P. M., Hustad, S. Mon, 28 Apr 2008 00:00:00 -0000

[Editorials] Estimating LDL ApoB: Infomania or Clinical Advance?
Burnett, J. R., Watts, G. F. Mon, 28 Apr 2008 00:00:00 -0000

[Perspective] Why a Cluster is Truly a Cluster: Insulin Resistance and Cardiovascular Disease
Reaven, G. Mon, 28 Apr 2008 00:00:00 -0000

[Review] Laboratory Assessment of HDL Heterogeneity and Function
Movva, R., Rader, D. J. Mon, 28 Apr 2008 00:00:00 -0000
Background: Plasma concentrations of HDL cholesterol (HDL-C) and its major protein component apolipoprotein (apo) A-I are strongly inversely associated with cardiovascular risk, leading to the concept that therapy to increase HDL-C and apoA-I concentrations would be antiatherosclerotic and protective against cardiovascular events. The recent failure of the drug torcetrapib, a cholesteryl ester transfer protein inhibitor that substantially increased HDL-C concentrations, has brought focus on the issues of HDL heterogeneity and function as distinct from HDL-C concentrations. Content: This review addresses the current state of knowledge regarding assays of HDL heterogeneity and function and their relationship to cardiovascular disease. HDL is highly heterogeneous, with subfractions that can be identified on the basis of density, size, charge, and protein composition, and the concept that certain subfractions of HDL may be better predictors of cardiovascular risk is attractive. In addition, HDL has been shown to have a variety of functions that may contribute to its cardiovascular protective effects, including promotion of macrophage cholesterol efflux and reverse cholesterol transport and antiinflammatory and nitric oxide–promoting effects. Summary: Robust laboratory assays of HDL subfractions and functions and validation of the usefulness of these assays for predicting cardiovascular risk and assessing response to therapeutic interventions are critically important and of great interest to cardiovascular clinicians and investigators and clinical chemists.
[Lipids, Lipoproteins, and Cardiovascular Risk Factors] Trends in Circulating Concentrations of Total Homocysteine among US Adolescents and Adults: Findings from the 1991-1994 and 1999-2004 National Health and Nutrition Examination Surveys
Pfeiffer, C. M., Osterloh, J. D., Kennedy-Stephenson, J., Picciano, M. F., Yetley, E. A., Rader, J. I., Johnson, C. L. Mon, 28 Apr 2008 00:00:00 -0000
Background: The National Health and Nutrition Examination Survey (NHANES) has monitored total homocysteine (tHcy) concentrations in a nationally-representative sample of the US population since 1991. Until recently, however, data could not be compared across survey periods because of changes in analytical methods and specimen matrices. Such an analysis of these data could supplement current knowledge regarding whether the US folic acid fortification program has modified national plasma tHcy concentrations. Methods: We examined tHcy data in the prefortification NHANES III survey (phase II, 1991–1994) and in 3 postfortification survey periods (1999–2000, 2001–2002, and 2003–2004). We applied method adjustment equations to the survey data based on method comparison studies of separate samples. Persons with chronic kidney disease were excluded from the analyses. Results: Mean plasma tHcy concentrations decreased by 8%, 9%, and 10% for adolescent, adult, and older men and by 6%, 3%, and 13% for women, respectively, from before to after fortification. Concentrations remained unchanged between the first and third postfortification survey periods. Prevalence estimates of increased plasma tHcy concentrations (>13 µmol/L) for older men and women decreased from prefortification (32% and 20%, respectively) to postfortification (14% and 5%, respectively) but remained unchanged thereafter (16% and 14%, respectively [males] and 5% and 9%, respectively [females]). Conclusions: After adjusting for method changes, we quantified a prefortification to postfortification decrease in circulating tHcy concentrations of about 10% in a national sample of the US population. This change is similar to effects seen in intervention trials with folic acid and in smaller observational studies.

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