Spatiotemporal precision and hemodynamic mechanism of optical point spreads in alert primates

In functional brain imaging there is controversy over which hemodynamic signal best represents neural activity. Intrinsic signal optical imaging (ISOI) suggests that the best signal is the early darkening observed at wavelengths absorbed preferentially by deoxyhemoglobin (HbR). It is assumed that this darkening or “initial dip” reports local conversion of oxyhemoglobin (HbO) to HbR, i.e., oxygen consumption caused by local neural activity, thus giving the most specific measure of such activity. The blood volume signal, by contrast, is believed to be more delayed and less specific. Here, we used multiwavelength ISOI to simultaneously map oxygenation and blood volume [i.e., total hemoglobin (HbT)] in primary visual cortex (V1) of the alert macaque. We found that the hemodynamic “point spread,” i.e., impulse response to a minimal visual stimulus, was as rapid and retinotopically specific when imaged by using blood volume as when using the initial dip. Quantitative separation of the imaged signal into HbR, HbO, and HbT showed, moreover, that the initial dip was dominated by a fast local increase in HbT, with no increase in HbR. We found only a delayed HbR decrease that was broader in retinotopic spread than HbO or HbT. Further, we show that the multiphasic time course of typical ISOI signals and the strength of the initial dip may reflect the temporal interplay of monophasic HbO, HbR, and HbT signals. Characterizing the hemodynamic response is important for understanding neurovascular coupling and elucidating the physiological basis of imaging techniques such as fMRI.     

Emergency department thoracotomy: nursing implications for pediatric cases

Cardiac arrest in the pediatric patient is an infrequent event. Although an emergency department thoracotomy is a potentially lifesaving procedure, it should be used in only a small, select group of patients. A literature review was conducted to determine the indications, surgical techniques, emergency procedures, and nursing responsibilities associated with an emergency department thoracotomy.     

Randomised controlled trial and cost consequences study comparing initial physiotherapy assessment and management with routine practice for selected patients in an accident and emergency department of an acute hospital

Objective: The Department of Health is reviewing the effectiveness of accident and emergency (A&E) departments. This study aimed to compare health and economic effects of physiotherapy initial assessment and management with routine practice in an A&E department.

Methods: Randomised controlled trial and cost and consequences study. Patients presenting at A&E were eligible if suspected at triage to have soft tissue injury without fracture. The efficacy end point was "days to return to usual activities". Secondary end points included patient satisfaction with their care and further health outcomes and cost data.

Results: 766 of 844 (915) patients were randomised. The median days before return to usual activities (available for 73% of those randomised) was greater in the physiotherapist group (41 days compared with 28.5 days; hazard ratio 0.85 p = 0.071). The physiotherapy group expressed greater satisfaction with their A&E care (on a scale of 1 to 5, median was 4.2 compared with 4.0, p<0.001), were more likely to be given advice and reassurance, and more likely to be provided with aids and appliances. Costs were the same between the two arms.

Conclusion: There is evidence that physiotherapy leads to a prolonged time before patients return to usual activities. This study shows no clear danger from physiotherapy intervention and long term outcomes may be different but given these findings, a best estimate is that introducing physiotherapist assessment will increase costs to the health service and society. Routine care should continue be provided unless there is some reason why it is not feasible to do so and an alternative must be found.

     

Cell biology and immunology of malaria

Malaria is a vector-borne infectious disease caused by unicellular parasites of the genus Plasmodium. These obligate intracellular parasites have the unique capacity to infect and replicate within erythrocytes, which are terminally differentiated host cells that lack antigen presentation pathways. Prior to the cyclic erythrocytic infections that cause the characteristic clinical symptoms of malaria, the parasite undergoes an essential and clinically silent expansion phase in the liver. By infecting privileged host cells, employing programs of complex life stage conversions and expressing varying immunodominant antigens, Plasmodium parasites have evolved mechanisms to downmodulate protective immune responses against ongoing and even future infections. Consequently, anti-malaria immunity develops only gradually over many years of repeated and multiple infections in endemic areas. The identification of immune correlates of protection among the abundant non-protective host responses remains a research priority. Understanding the molecular and immunological mechanisms of the crosstalk between the parasite and the host is a prerequisite for the rational discovery and development of a safe, affordable, and protective anti-malaria vaccine.     

Reduced levodopa-induced complications after 5 years of subthalamic stimulation in Parkinson’s disease: a second honeymoon

The purpose of this paper is to describe the effect of 5 years of subthalamic nucleus deep brain stimulation (STN DBS) on levodopa-induced complications, both in everyday life and during an acute challenge with levodopa. Thirty three patients were evaluated during an acute levodopa challenge before surgery and then 1 and 5 years afterwards (both off stim and on stim), using the UPDRS III scale and the CAPSIT-PD scales for dystonia and peak-dose dyskinesia. The UPDRS IV scale was used to assess motor complications in everyday life. The levodopa daily dose and DBS parameters were also recorded. Levodopa-induced complications in everyday life (UPDRS IV) and during an acute levodopa challenge had improved markedly after 1 year (both on and off stim) and still further at 5 years. Peak-dose dyskinesia decreased between the 1- and 5-year measurements. STN DBS decreases levodopa-induced motor complications over the long term. This phenomenon may be explained by (a) overall stabilization of the basal ganglia network and (b) striatal synaptic changes. Our results suggest that DBS leads to both qualitative and quantitative modulations in the corticostriatal loops.