Single-isomer drugs are of great importance in modern therapeutics. In this article, the basics of the underlying phenomenon are explained. Some molecules are chiral, ie, their mirror image is not superposable on the original. The most common element producing molecular chirality is a chiral center, typically a carbon atom carrying four different groups. The mirror-image molecules are termed enantiomers, but the less specific terms stereoisomers and isomers are also used. A substance consisting of only one of the two enantiomers is a single enantiomer or single isomer, and the 1:1 mixture of the enantiomers is the racemic mixture or racemate. A graphical convention that conveys the three-dimensional aspects of chiral molecules drawn in two dimensions, as well as two nongraphical conventions, based on optical rotation and configuration, are used to identify enantiomers. Optical rotation is a physical property of single enantiomers and involves rotation of the plane of plane-polarized light, each pure enantiomer rotating with equal magnitude but in the opposite direction (dextro and levo). Configuration is the actual arrangement in space of the atoms of chiral molecules. Two systems of indicating configuration are in use. One employs D and L to denote the respective enantiomers, and is applicable only to α-amino acids and carbohydrates. The other is a universal system using R and S as descriptors for the two possible arrangements, respectively, of the atoms around the chiral center. Interest in chiral drugs stems from the frequently observed biological differences between enantiomers. Such enantioselectivity is the result of different interactions of the drug enantiomers with target receptors that are themselves chiral and single-enantiomeric.

There is little research on the consequences of large-scale violent disasters in a community despite their unfortunate prevalence over many decades. The primary source of epidemiological data for the greater New York community in dealing with the September 11, 2001, attacks was the Oklahoma City bombing. In the latter event, 45% of directly exposed adults met criteria for a major psychiatric disorder 6 months later, including 34% with posttraumatic stress disorder (PTSD). The first survey after the World Trade Center and Pentagon attacks, conducted within one week, revealed a remarkable degree of symptomatology across the nation in both adults and children. Forty-four percent of adults reported at least 1 of 5 PTSD screening symptoms in the 3–5 days after the attacks; 35% of parents reported children who had at least one symptom, and 47% of children worried about their own or someone else's safety. Coping behaviors were consistent with a community mental health model and included turning to open discussion (98%), religion (90%), and community activities (60%) in order to cope with their reactions.

Rates of disorder were also high in a survey conducted 5–8 weeks later in Manhattan below 110th Street, with 38% saying they directly witnessed the World Trade Center attack. The current prevalence of new-onset PTSD was 7.5%, and of new-onset major depressive disorder, 9.7%. This translates into 67,000 persons with PTSD and 87,000 persons with major depression. This survey also found a significant increase in tobacco, alcohol, and marijuana use, but primarily among adults already using these substances. All surveys found strong associations between media exposure and symptomatology. The greatest need at this point in the literature is therapeutics research after such traumatic events.

A centenary is often an excuse for reminding people of the life and work of a predecessor, especially if the material is of contemporary relevance. Published 100 years ago, William James' The Varieties of Religious Experience, remains the most revealing investigation into the psychology of religion. James, a nonpracticing MD, turned his thoughts to psychology and philosophy. The book was considered “one of the great books of our time” and in it, James bravely tackled a subject that many then, and perhaps now, considered taboo.

James' aim was to study religious experiences as he would any other psychological phenomena, accepting their reality and vulnerability to scientific enquiry. His definition of religion was “the feelings, acts, and experiences of individual men in their solitude, so far as they apprehend themselves to stand in relation to whatever they may consider the divine.” He was concerned with immediate personal experiences, which he considered to be universal to humanity.

In his lecture, “Religion and Neurology,” he explored the potential psychophysical associations of religious feelings. In order to understand the nature of religious experience, James emphasized the need to study those for whom religion was “an acute fever,” and not to dwell long on those whose commerce with the deity was “second hand.” The ones to study were the “geniuses of the religious line.” However, he warned that they “like many other geniuses that have brought forth fruits effective enough for commemoration in the pages of biography, have often shown symptoms of nervous instability.” He pointed out that “insane conditions” have a considerable advantage for studies of this kind because they isolate specific factors of the mental life that become available for investigation.

Until relatively recently the three-dimensional nature of drug molecules has been largely neglected, with approximately 25% of marketed drugs being mixtures of agents rather than single chemical entities. These mixtures are not combinations of drugs but mixtures of stereoisomers, generally racemates of synthetic chiral drugs. The individual enantiomers present in such mixtures frequently differ in both their pharmacodynamic and pharmacokinetic profiles as a result of stereochemical discrimination on interaction with chiral biological macromolecules (enzymes and receptors). The use of such mixtures may present problems if their adverse effects are associated with the less active stereoisomer or do not show stereoselectivity. In addition, interactions between enantiomers may occur such that the observed activity of the racemate is not simply the product of the effects of the individual enantiomers. Since the mid-1980s there has been an ongoing “racemate-versus-enantiomer” debate with the potential advantages of single-isomer products, including improved selectivity of action and potential increase in therapeutic index, being highlighted. As a result, regulatory authorities have issued guidelines for dealing with chiral molecules, and the number of single enantiomer agents presented for evaluation has increased. Racemic mixtures may still be developed but require justification such that the risk-benefit ratio may be assessed. In addition to new chemical entities, a number of “old” mixtures are being re-examined as potential single-isomer products, the chiral switches, with the potential for an improved therapeutic profile and possibly new indications. However, for the majority of agents currently marketed as mixtures, relatively little is known concerning the pharmacological or toxicological properties of the individual enantiomers.

How did the 1995 Oklahoma City bombing differ from prior disasters and what implications did it have for disaster mental health services and service delivery? The federal disaster mental health approach in this country developed largely out of experiences with natural disasters. The 1995 Oklahoma City bombing differed in several important ways, including the large number of human casualties, higher rates of psychopathology, and an extended period of concern due to the criminal investigation and trials, which suggested the need to consider modifications in the program. Outreach was extensive, but psychiatric morbidity of direct victims was greater than that of victims of natural disasters, emphasizing the need for attention to the triage and referral process. Other concerns that warrant consideration include practices related to record keeping and program evaluation.