Halogen bonding has been extensively described in the context of a variety of self-assembled supramolecular systems and efficiently utilized in the rational design of materials with specific structural properties. However, it has so far received only little recognition for its possible role in the stabilization of small molecule–protein complexes. In this tutorial review, we provide a few examples of halogen bonds occurring between small halogen-substituted ligands and their biological substrates. Examples were drawn from a diverse set of compounds, ranging from chemical additives and possible environmental agents such as triclosan to pharmacologically active principles such as the volatile anesthetic halothane or HIV-1 reverse transcriptase inhibitors or a subset of non-steroidal anti-inflammatory drugs (NSAIDs) that are halogen-substituted. The crystal structures presented here, where iodine, bromine, or chlorine atoms function as halogen bonding donors and a variety of electron rich sites, such as oxygen, nitrogen and sulfur atoms, as well as aromatic π-electron systems, function as halogen bonding acceptors, prove how halogen bonds can occur in biological systems and provide a class of highly directional stabilizing contacts that can be exploited in the process of rational drug design.

The murine Ly6 complex was identified 35 years ago using antisera to lymphocytes. With advances in mAb development, molecular cloning, and genome sequencing, >20 structurally related genes have been identified within this complex on chromosome 15. All members of the Ly6 family and their human homologues share the highly conserved LU domain and most also possess a GPI anchor. Interestingly, many Ly6 proteins are expressed in a lineage-specific fashion, and their expression often correlates with stages of differentiation. As a result, Ly6 proteins are frequently used as surface markers for leukocyte subset identification and targets for antibody-mediated depletion. Murine neutrophils display prominent surface expression of several Ly6 proteins, including Ly6B, Ly6C, and Ly6G. Although the physiology of most Ly6 proteins is not well understood, a role in neutrophil functions, such as migration, is recognized increasingly. In this review, we will provide an overview of the Ly6 complex and discuss, in detail, the specific Ly6 proteins implicated in neutrophil biology.

The catalytic properties of some selected enzymes have long been exploited to carry out efficient and cost-effective bioconversions in a multitude of research and industrial sectors, such as food, health, cosmetics, agriculture, chemistry, energy, and others. Nonetheless, for several applications, naturally occurring enzymes are not considered to be viable options owing to their limited stability in the required working conditions. Over the years, the quest for novel enzymes with actual potential for biotechnological applications has involved various complementary approaches such as mining enzyme variants from organisms living in extreme conditions (extremophiles), mimicking evolution in the laboratory to develop more stable enzyme variants, and more recently, using rational, computer-assisted enzyme engineering strategies. In this review, we provide an overview of the most relevant enzymes that are used for industrial applications and we discuss the strategies that are adopted to enhance enzyme stability and/or activity, along with some of the most relevant achievements. In all living species, many different enzymes catalyze fundamental chemical reactions with high substrate specificity and rate enhancements. Besides specificity, enzymes also possess many other favorable properties, such as, for instance, cost-effectiveness, good stability under mild pH and temperature conditions, generally low toxicity levels, and ease of termination of activity. As efficient natural biocatalysts, enzymes provide great opportunities to carry out important chemical reactions in several research and industrial settings, ranging from food to pharmaceutical, cosmetic, agricultural, and other crucial economic sectors.

The potential risk for travel-related venous thromboembolism (VTE) has become an important public health concern because of rapid increases in long-distance travel; however, previous studies on this relationship are surprisingly contradictory. To estimate the risk for VTE in travelers, determine whether a dose–response relationship exists, and identify reasons for the contradictory results of previous studies. MEDLINE, EMBASE, BIOSIS, CINAHL, grey-literature sources, contact with investigators, and reference lists of studies, without language restrictions. Reports were selected if they investigated the association between travel and VTE for persons who used any mode of transportation and if nontraveling persons were included for comparison. Data on study and patient characteristics, risk estimates, and quality were independently extracted by 2 investigators. Pooled effect estimates were obtained by using random-effect meta-analysis. Of 1560 identified abstracts, 14 studies (11 case–control, 2 cohort, and 1 case–crossover) met inclusion criteria, including 4055 cases of VTE. Compared with nontravelers, the overall pooled relative risk for VTE in travelers was 2.0 (95% CI, 1.5 to 2.7). Significant heterogeneity was present because of the method for selecting control participants (P = 0.008): whether the studies used control participants who had been referred for VTE evaluation or nonreferred control participants. When the studies that used referred control participants were excluded, the pooled relative risk for VTE in travelers was 2.8 (CI, 2.2 to 3.7), without significant heterogeneity. A dose–response relationship was identified, with an 18% higher risk for VTE for each 2-hour increase in duration of travel by any mode (P = 0.010) and a 26% higher risk for every 2 hours of air travel (P = 0.005). All available studies were from Western countries; generalizability to non-Western populations is expected but needs confirmation. Travel is associated with a nearly 3-fold higher risk for VTE, with a dose–response relationship of 18% higher risk for each 2-hour increase in travel duration. Heterogeneity in results of previous studies was due to selection bias toward the null from use of referred control participants.