Response to comment on 'Protein crystal lattices are dynamic assemblies: the role of conformational entropy in the protein condensed phase'.

A response is given to Nespolo's comment [IUCrJ (2018), 5, https://doi.org/10.1107/S2052252518006267] about the usage of the the term 'crystal lattice' in Dimova & Devedjiev [IUCrJ (2018), 5, 130-140].

Protein crystal lattices are dynamic assemblies: the role of conformational entropy in the protein condensed phase.

Until recently, the occurrence of conformational entropy in protein crystal contacts was considered to be a very unlikely event. A study based on the most accurately refined protein structures demonstrated that side-chain conformational entropy and static disorder might be common in protein crystal lattices. The present investigation uses structures refined using ensemble refinement to show that although paradoxical, conformational entropy is likely to be the major factor in the emergence and integrity of the protein condensed phase. This study reveals that the role of shape entropy and local entropic forces expands beyond the onset of crystallization. For the first time, the complete pattern of intermolecular interactions by protein atoms in crystal lattices is presented, which shows that van der Waals interactions dominate in crystal formation.

An ethnographic exploration of drug markets in Kisumu, Kenya.

BACKGROUND: Illegal drug markets are shaped by multiple forces, including local actors and broader economic, political, social, and criminal justice systems that intertwine to impact health and social wellbeing. Ethnographic analyses that interrogate multiple dimensions of drug markets may offer both applied and theoretical insights into drug use, particularly in developing nations where new markets and local patterns of use traditionally have not been well understood. This paper explores the emergent drug market in Kisumu, western Kenya, where our research team recently documented evidence of injection drug use. METHODS: Our exploratory study of injection drug use was conducted in Kisumu from 2013 to 2014. We draw on 151 surveys, 29 in-depth interviews, and 8 months of ethnographic fieldwork to describe the drug market from the perspective of injectors, focusing on their perceptions of the market and reports of drug use therein. RESULTS: Injectors described a dynamic market in which the availability of drugs and proliferation of injection drug use have taken on growing importance in Kisumu. In addition to reports of white and brown forms of heroin and concerns about drug adulteration in the market, we unexpectedly documented widespread perceptions of cocaine availability and injection in Kisumu. Examining price data and socio-pharmacological experiences of cocaine injection left us with unconfirmed evidence of its existence, but opened further possibilities about how the chaos of new drug markets and diffusion of injection-related beliefs and practices may lend insight into the sociopolitical context of western Kenya. CONCLUSIONS: We suggest a need for expanded drug surveillance, education and programming responsive to local conditions, and further ethnographic inquiry into the social meanings of emergent drug markets in Kenya and across sub-Saharan Africa.

A qualitative analysis of transitions to heroin injection in Kenya: implications for HIV prevention and harm reduction.

BACKGROUND: Heroin injection is emerging as a significant dimension of the HIV epidemic in Kenya. Preventing transitions to injecting drug use from less harmful forms of use, such as smoking, is a potentially important focus for HIV prevention. There is, however, little evidence to support comprehensive programming in this area, linked to a shortage of analysis of the social and structural context for transitions, particularly in low-income settings. We explore accounts of transitions from smoking to injecting in Kenya to understand the role of individual, social and structural processes. METHODS: We combine data from two separate studies conducted in Kenya: an in-depth qualitative study of HIV care access for people who inject drugs (study 1) and an ethnographic study of the political economy of the heroin trade in Kenya (study 2). In-depth interviews with PWID and community observation from study 1 are triangulated with accounts from stakeholders involved in the heroin trade and documentary data from study 2. RESULTS: People who inject drugs link transitions to injecting from smoking to a range of social and behavioural factors, as well as particular aspects of the local drug supply and economy. We present these results in the form of two narratives that account for factors shaping transitions. A dominant narrative of 'managing markets and maintaining a high' results from a process of trying to manage poverty and a shifting heroin supply, in the context of deepening addiction to heroin. A secondary narrative focuses on people's curiosity for the 'feeling' of injecting, and the potential pleasure from it, with less emphasis on structural circumstances. CONCLUSIONS: The narratives we describe represent pathways through which structural and social factors interact with individual experiences of addiction to increase the risk of transitions to injecting. In response, HIV and harm reduction programmes need combinations of different strategies to respond to varied experiences of transitions. These strategies should include, alongside behaviour-oriented interventions, structural interventions to address economic vulnerability and the policing of the drug supply.