Systematic functional analysis of Leishmania protein kinases identifies regulators of differentiation or survival.

Differentiation between distinct stages is fundamental for the life cycle of intracellular protozoan parasites and for transmission between hosts, requiring stringent spatial and temporal regulation. Here, we apply kinome-wide gene deletion and gene tagging in Leishmania mexicana promastigotes to define protein kinases with life cycle transition roles. Whilst 162 are dispensable, 44 protein kinase genes are refractory to deletion in promastigotes and are likely core genes required for parasite replication. Phenotyping of pooled gene deletion mutants using bar-seq and projection pursuit clustering reveal functional phenotypic groups of protein kinases involved in differentiation from metacyclic promastigote to amastigote, growth and survival in macrophages and mice, colonisation of the sand fly and motility. This unbiased interrogation of protein kinase function in Leishmania allows targeted investigation of organelle-associated signalling pathways required for successful intracellular parasitism.

Investigating the Swimming of Microbial Pathogens Using Digital Holography.

To understand much of the behaviour of microbial pathogens, it is necessary to image living cells, their interactions with each other and with host cells. Species such as Escherichia coli are difficult subjects to image: they are typically microscopic, colourless and transparent. Traditional cell visualisation techniques such as fluorescent tagging or phase-contrast microscopy give excellent information on cell behaviour in two dimensions, but no information about cells moving in three dimensions. We review the use of digital holographic microscopy for three-dimensional imaging at high speeds, and demonstrate its use for capturing the shape and swimming behaviour of three important model pathogens: E. coli, Plasmodium spp. and Leishmania spp.

Fast, high-throughput measurement of collective behaviour in a bacterial population.

Swimming bacteria explore their environment by performing a random walk, which is biased in response to, for example, chemical stimuli, resulting in a collective drift of bacterial populations towards 'a better life'. This phenomenon, called chemotaxis, is one of the best known forms of collective behaviour in bacteria, crucial for bacterial survival and virulence. Both single-cell and macroscopic assays have investigated bacterial behaviours. However, theories that relate the two scales have previously been difficult to test directly. We present an image analysis method, inspired by light scattering, which measures the average collective motion of thousands of bacteria simultaneously. Using this method, a time-varying collective drift as small as 50 nm s(-1) can be measured. The method, validated using simulations, was applied to chemotactic Escherichia coli bacteria in linear gradients of the attractant α-methylaspartate. This enabled us to test a coarse-grained minimal model of chemotaxis. Our results clearly map the onset of receptor methylation, and the transition from linear to logarithmic sensing in the bacterial response to an external chemoeffector. Our method is broadly applicable to problems involving the measurement of collective drift with high time resolution, such as cell migration and fluid flows measurements, and enables fast screening of tactic behaviours.

Degraded auditory processing in a rat model of autism limits the speech representation in non-primary auditory cortex.

Although individuals with autism are known to have significant communication problems, the cellular mechanisms responsible for impaired communication are poorly understood. Valproic acid (VPA) is an anticonvulsant that is a known risk factor for autism in prenatally exposed children. Prenatal VPA exposure in rats causes numerous neural and behavioral abnormalities that mimic autism. We predicted that VPA exposure may lead to auditory processing impairments which may contribute to the deficits in communication observed in individuals with autism. In this study, we document auditory cortex responses in rats prenatally exposed to VPA. We recorded local field potentials and multiunit responses to speech sounds in primary auditory cortex, anterior auditory field, ventral auditory field. and posterior auditory field in VPA exposed and control rats. Prenatal VPA exposure severely degrades the precise spatiotemporal patterns evoked by speech sounds in secondary, but not primary auditory cortex. This result parallels findings in humans and suggests that secondary auditory fields may be more sensitive to environmental disturbances and may provide insight into possible mechanisms related to auditory deficits in individuals with autism.

Differential dynamic microscopy of bacterial motility.

We demonstrate a method for the fast, high-throughput characterization of the dynamics of active particles. Specifically, we measure the swimming speed distribution and motile cell fraction in Escherichia coli suspensions. By averaging over ∼10(4) cells, our method is highly accurate compared to conventional tracking, yielding a routine tool for motility characterization. We find that the diffusivity of nonmotile cells is enhanced in proportion to the concentration of motile cells.

Passive and active microrheology of hard-sphere colloids.

We performed passive and active microrheology using probe particles in a bath of well-characterized, model hard-sphere colloids in the fluid state over the whole range of volume fractions below the glass transition. The probe and bath particles have nearly the same size. Passive tracking of probe particles yields short-time self-diffusion coefficients. Comparison with literature data demonstrates that the interaction between probe and bath particles is hard-sphere-like. The short-time diffusivities yield one set of microviscosities as a function of volume fraction, which agrees with previous macrorheological measurements of the high-frequency viscosity of hard-sphere colloids. Using optical tweezers, we measure the force on a trapped probe particle as the rest of the sample is translated at constant velocity. This yields a second set of microviscosities at high Péclet numbers. These agree with previous macrorheological measurements of the high-shear viscosity of similar colloids, at shear-rates below the onset of shear-thickening.

Post-traumatic stress symptoms and distress 1 year after burn injury.

The occurrence and predictors of post-traumatic stress symptoms 1 year after a burn injury were assessed in a large prospective sample (N = 172). Participants completed a self-report post-traumatic stress symptom checklist at 3 time points: within 24 hours of admission to a burn center, 1 month after the injury, and 1 year after the injury. A notable number of participants had a range of post-traumatic stress symptoms both at 1 month and at 1 year after the burn injury. More than half of the sample reported recurrent intrusive recollections of the burn injury at 1 month and at 1 year. Other commonly endorsed symptoms were sleep disturbance, avoidance of thoughts or feelings associated with the burn, and distress at reminders of the burn. The number of post-traumatic stress symptoms endorsed at 1 month was the only significant predictor of post-traumatic stress symptoms at 1 year. These results suggest that it is common for patients to have some post-traumatic symptoms 1 year after a burn injury and that early experiences of post-traumatic stress symptoms may be associated with the development or maintenance of post-traumatic stress disorder. We recommend that burn care professionals identify and intervene with patients who have clinically significant distress as a result of their burn injuries.

Post-traumatic stress symptoms and distress following acute burn injury.

The occurrence and predictors of acute post-traumatic stress symptoms were assessed in a large, prospective sample of persons with new burn injuries (N = 172). Participants completed a self-report post-traumatic stress symptom checklist, pain ratings, and a premorbid mental health inventory within 24 h of admission to a burn center (Day 1). Over half of the sample reported sleep disturbance and recurrent, intrusive recollections of the burn injury on Day 1. Other commonly endorsed symptoms were difficulties concentrating, avoidance of thoughts/feelings associated with the burn, flashbacks, and exaggerated startle response. Persons with less favorable premorbid mental health and larger burns reported a greater number of stress symptoms on Day 1. These results suggest that experiencing some post-traumatic stress symptoms immediately following a burn trauma is normal. It is recommended that burn care professionals identify and intervene with patients who are suffering clinically significant distress early in the hospitalization.

Human rights of psychiatrically disturbed persons in the tropical Pacific.

The management of acutely disturbed patients in smaller Pacific island communities presents many clinical challenges as well as ethical and human rights questions. The aggressive, excited, sexually inappropriate, and possibly violent disturbed person frequently will need physical restraint and possible seclusion in a secure environment. In practical terms, on many Pacific islands the only physically secure room is a jail cell. This environment will protect others and possibly protect the out-of-control person from themselves. After protection, the next requirements are adequate information about the person and clinically informed individuals who can make a diagnosis and commence treatment in the jail environment. Adequately trained people who can diagnose and suggest initial treatment are few and widely dispersed in Pacific island communities. Two representative case vignettes from the author's experience as a World Health Organization short-term consultant in Tonga and the Commonwealth of the Northern Mariana islands illustrate the tension between a disturbed person's right to adequate treatment and the right of a citizen/patient to be free of coercion.

A profile of medically serious suicide attempts.

BACKGROUND: This study identified factors associated with medically serious suicide attempts (requiring medical hospitalization). METHOD: Demographic information, current psychiatric mental state, suicide attempt and psychiatric history characteristics, and DSM-IV diagnoses were compared between 65 patients hospitalized for a medically serious suicide attempt (MSSA) and 32 patients seen in the emergency room for suicide attempt but not medically hospitalized (NMSSA). RESULTS: Those with MSSAs had a higher rate of substance-induced mood disorder (but not substance abuse or dependence), while those with NMSSA had more attempts, more years since first attempt, and a higher rate of sexual and physical abuse, traumatic life events, borderline personality disorder, and bipolar disorder. CONCLUSION: Substance-induced mood disorder is an important diagnosis in the evaluation of suicidal patients. The vulnerability of mood effects caused by substance abuse may lead to a more serious suicide attempt despite less extensive psychiatric problems. The most important early psychiatric intervention may be the immediate recognition and aggressive treatment of an individual's affective and substance use disorders.

The crime of saving lives. The FDA, John Najarian, and Minnesota ALG.

The indictment of John Najarian, MD, and Richard Condie at Minneapolis, Minn, on April 10, 1995, was a defining episode in the prolonged agony that has ensued since August 1992, when the federal Food and Drug Administration (FDA) placed Minnesota Anti-Lymphocyte Globulin (MALG) on clinical hold, bringing to an end its use as an immunosuppressive agent for patients undergoing transplantation. The principal charge in the indictment is that from about 1968 until 1992--the whole period of the development and use of MALG--Dr Najarian and Mr Condie conspired to defraud the United States by impeding the FDA in its oversight of biological drugs and that they did so for the purpose of financial gain. If the charges can be considered seriously, they mean that Dr Najarian's purpose in the development and manufacture of MALG was to make money, presumably for himself, and that the possible benefit of MALG to the patients was of secondary concern to him. Several difficulties arise immediately. In 1968, MALG offered a promising new approach to immunosuppression. In a relatively crude form, it had been used at the University of Colorado with striking improvement in the survival of patients undergoing transplantation and transplanted organs, but it was painful to administer by intramuscular injections and, in addition to other side effects, produced muscular spasms. Dr Najarian and his colleagues succeeded in purifying MALG so that the pure globulin could be injected into a central vein. The process of purification was complicated and expensive, so it was hardly practical for each transplant center to produce MALG for itself. Thus, in 1969, when Dr Najarian submitted an investigational new drug application (IND) to the FDA, he stated that his purpose was to manufacture MALG not only for patients at the University of Minnesota Hospital but also for patients at other transplant centers, which were not in a position to make it for themselves. He asked the FDA to approve recovery of the cost of providing MALG to other institutions. The FDA approved Dr Najarian's IND application early in 1970 but did not respond to his request for cost recovery--then, or for the next 15 years. Dr Najarian was free to manufacture MALG and to distribute it to other transplant centers for investigational use, but as for paying for it, that was his problem. The FDA offered no suggestion.

Transient uniocular blindness after dental extraction under general anaesthetic.

A 14-year-old boy suffered transient uniocular blindness after extraction of four permanent first molar teeth under general anaesthetic. We discuss the theoretical basis for ocular vasospasm secondary to the minor trauma of dental extraction being relayed to the orbit.

Dawn simulation treatment of winter depression: a controlled study.

OBJECTIVE: This study sought to determine whether dawn simulation was superior to a shorter dimmer "placebo" dawn signal in treating winter depression. METHOD: In a randomized, parallel design, 22 patients with winter depression were treated with either 1 week of a 2-hour dawn simulation peaking at 250 lux or 1 week of a 30-minute dawn simulation peaking at 0.2 lux. The subjects were told that they would receive either a "gradual" dawn or a "rapid" dawn reaching an intensity that would be dimmer than standard bright light treatment. At the end of both the baseline week and the treatment week, subjects were assessed in a blind manner with the Hamilton Rating Scale for Depression. Analysis of covariance was used to compare the two dawn treatments. RESULTS: The 2-hour, 250-lux dawn simulation resulted in Hamilton depression scale scores that were significantly lower than scores after the 30-minute, 0.2-lux dawn simulation. CONCLUSIONS: This study indicates that dawn simulation is an effective treatment for winter depression.

Localisation of corneal foreign bodies.

Of 50 patients attending the eye casualty department with a corneal foreign body (FB), 41 were able to say where they felt the FB and 78% of these were localised correctly for side or level of cornea. Patient handedness did not influence FB location. Indicating the upper lid was a particularly poor guide to localisation, whereas FB sensations within the palpebral fissure, in the lower lid or medially or laterally were good guides to actual FB location. A simple method of recording FB location by zone and clock hour is proposed.

Spontaneous passage of a dacryolith.

A patient had four episodes of recurrent dacryolith over 14 years. Each attack of acutely painful dacryocystitis was terminated by spontaneous passage of the dacryolith. Biochemical and dacryocystographic evidence help to explain the pathogenesis of the condition.