014 Diurnal changes in perineuronal nets and parvalbumin neurons in the rat medial prefrontal cortex

Introduction

Perineuronal nets (PNNs) surrounding fast-spiking, parvalbumin (PV) interneurons provide excitatory:inhibitory balance within cortical circuits. This balance is impaired in several disorders that are also associated with altered diurnal rhythms, yet few studies examined diurnal rhythms of PNNs or PV cells.

Methods

We measured the intensity and number of PV cells and PNNs labeled with Wisteria floribunda agglutinin (WFA) and also the oxidative stress marker 8-oxo-deoxyguanosine (8-oxo-dG) in rat prelimbic medial prefrontal cortex (mPFC) at Zeitgeber times (ZT) ZT0, 6, 12, and 18. To examine changes in inhibitory and excitatory inputs to PV cells, we measured GAD 65/67 and vGLUT1 puncta apposed to PV cells with and without PNNs. Whole-cell slice recordings in fast-spiking (PV) cells with PNNs was conducted to determine the ratio of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor:N-methyl-D-aspartate receptor (AMPA:NMDA) at ZT18 vs. ZT6. Finally, the number of PV cells and PV/PNN cells containing orthodenticle homeobox 2 (OTX2), which maintains PNNs, was also assessed.

Results

Relative to ZT0, the intensities of PNN and PV labeling were increased in the dark compared with the light phase. The intensity of 8-oxo-dG was decreased from ZT0 at all times. There were more excitatory puncta on PV cells with PNNs at ZT18 vs. ZT6, but no changes in PV cells without PNNs and no changes in inhibitory puncta. There was an increased AMPA:NMDA ratio at ZT18 vs. ZT6. The number of PV cells and PV/PNN cells containing OTX2 showed a strong trend toward an increase from ZT6 to ZT18, with no differences in non-PV-containing cells.

Conclusion

Diurnal fluctuations in PNNs and PV cells alter cortical excitatory:inhibitory balance. Detailed understanding of how these fluctuations are regulated should provide new insights into treatments for diseases impacted by disturbances in sleep and circadian rhythms. Ongoing studies are examining diurnal fluctuations in downstream signaling after PNN removal.

Support (if any)

Washington State University Alcohol and Drug Abuse Research Program, NIH GM134789 (JHH); NIH DA033404 (BAS), DA040965 (BAS, TEB, SAA); NIH NS078498 (JPW); NIH P30 NS061800 (SAA); and Agence Nationale de la Recherche ANR-18-CE16-0013-01 (AP and AAD).

Virtual HIV pre-exposure prophylaxis outpatient service in the era of COVID-19

In the midst of the COVID-19 pandemic, health care providers have had to rapidly change how they deliver care to patients. We discuss how we are delivering a virtual HIV pre-exposure prophylaxis (PrEP) service during this time; challenges faced; challenges expected and goals for the coming months.

The Transit/Admission Lounge study

In response to persistent overcrowding of Emergency Departments in Ireland, the Department of Health and Health Service Executive provided funding for "Transit Lounge" areas to be built. These lounges were to provide a location for patients to wait in beds pending the availability of a ward bed. This research was performed to assess the impact of such a lounge on the overcrowding of the Emergency Department and on patient outcomes. The time period from the opening of the Transit Lounge was compared with the same period a year earlier. The Transit Lounge delivers a comfortable place for patients to wait. It does not reduce Emergency Department overcrowding and has been associated with an increased time waiting for a ward bed. The solution to overcrowding is the creation of real capacity in the system so that ward beds are available in acute hospitals for the "unscheduled unwell".

Why are we waiting? A study of the patients' perspectives about their protracted stays in an emergency department

The overcrowding of Emergency Departments compromises their critical function and the safety of patients and staff. This study asked the patients how the wait in overcrowded conditions impacted on them and the care they received and what they believed the reasons for the overcrowding were. A prospective questionnaire based structured interview study was performed. Over half (57.7%) of patients felt that the lack of inpatient beds and wards was the main reason that they experienced delays. An overwhelming 85.9% felt that the Health Authorities were not doing enough to address the overcrowding issue. Overcrowding of Emergency Departments has been identified as a major problem the solution is to be found in increasing the capacity of the acute hospital system according to the majority of our study population.

To lead or not to lead? Prospective controlled study of emergency nurses' provision of advanced life support team leadership

BACKGROUND AND OBJECTIVES

In many emergency departments advanced life support (ALS) trained nurses do not assume a lead role in advanced resuscitation. This study investigated whether emergency nurses with previous ALS training provided good team leadership in a simulated cardiac arrest situation.

METHODS

A prospective study was conducted at five emergency departments and one nurses' association meeting. All participants went through the same scenario. Details recorded included baseline blood pressure and pulse rate, time in post, time of ALS training, and subjective stress score (1 = hardly stressed; 10 = extremely stressed). Scoring took into account scenario understanding, rhythm recognition, time to defibrillation, appropriateness of interventions, and theoretical knowledge.

RESULTS

Of 57 participants, 20 were ALS trained nurses, 19 were ALS trained emergency senior house officers (SHOs), and 18 were emergency SHOs without formal ALS training. The overall mean score for doctors without ALS training was 69.5%, compared with 72.3% for ALS trained doctors and 73.7% for ALS trained nurses. Nurses found the experience less stressful (subjective stress score 5.78/10) compared with doctors without ALS training (6.5/10). The mean time taken to defibrillate from the appearance of a shockable rhythm on the monitor by the nurses and those SHOs without ALS training was 42 and 40.8 seconds, respectively.

CONCLUSION

ALS trained nurses performed as well as ALS trained and non ALS trained emergency SHOs in a simulated cardiac arrest situation and had greater awareness of the potentially reversible causes of cardiac arrest. Thus if a senior or middle grade doctor is not available to lead the resuscitation team, it may be appropriate for experienced nursing staff with ALS training to act as ALS team leaders rather than SHOs.

A conditional deletion of the NR1 subunit of the NMDA receptor in adult spinal cord dorsal horn reduces NMDA currents and injury-induced pain

To determine the importance of the NMDA receptor (NMDAR) in pain hypersensitivity after injury, the NMDAR1 (NR1) subunit was selectively deleted in the lumbar spinal cord of adult mice by the localized injection of an adenoassociated virus expressing Cre recombinase into floxed NR1 mice. NR1 subunit mRNA and dendritic protein are reduced by 80% in the area of the virus injection, and NMDA currents, but not AMPA currents, are reduced 86-88% in lamina II neurons. The spatial NR1 knock-out does not alter heat or cold paw-withdrawal latencies, mechanical threshold, or motor function. However, injury-induced pain produced by intraplantar formalin is reduced by 70%. Our results demonstrate conclusively that the postsynaptic NR1 receptor subunit in the lumbar dorsal horn of the spinal cord is required for central sensitization, the central facilitation of pain transmission produced by peripheral injury.

The point of the needle. Occult pneumothorax: a review

The case of a patient with an unusual medical condition and an occult pneumothorax is presented. The evidence for management of occult pneumothorax particularly in patients with underlying lung disease is reviewed and solutions to the acute clinical problems that may arise are suggested.

Early post-tonsillectomy morbidity following hospital discharge: do patients and GPs know what to expect?

Tonsillectomy is a commonly performed operation; like many others there is increasing pressure for it to be performed as a day-case procedure, with no follow-up for the majority of patients. This paper presents the results of a prospective study of the incidence of post-tonsillectomy morbidity, the recognition of these symptoms by patients, and their management by general practitioners. The results indicate: a lack of awareness by patients of symptoms they might expect post-operatively, despite written and verbal information given; an over-prescription of antibiotics by general practitioners for normal post-operative symptoms such as throat pain, temporary voice changes and referred otalgia; and a failure by patients to recognise the importance of the potentially life-threatening complication of secondary haemorrhage from the tonsillar bed.