Functional MRI and other non-invasive imaging technologies: providing visual biomarkers for spinal cord structure and function after injury

Substantial progress has been made towards understanding the molecular basis for limited endogenous central nervous system (CNS) axonal growth after injuries such as spinal cord trauma. Realization of the potential benefit of therapeutic interventions requires methods to assess axonal growth and functional reorganization over time after neurological damage. Here, we discuss the technical challenges of analyzing and interpreting the effects of various interventions on CNS repair, specifically in the context of spinal cord injury. Evolving technologies such as functional magnetic resonance imaging and other non-invasive imaging techniques will be reviewed. These technologies should revolutionize our ability to track changes in both CNS structure and function.     

Gravid hysterectomy following history of recurrent ruptured uterus: case report

The risk of uterine rupture and its associated morbidities increases as the incidence of cesarean deliveries increases. There is little evidence guiding the management of pregnancy termination in patients with a history of uterine rupture. A 21-year-old woman with a history of a classical cesarean delivery and four subsequent uterine ruptures presented for termination of pregnancy at 17 weeks and 2 days. Ultrasound study noted anterior wall implantation of the placenta covering the classical cesarean scar as well as the subsequent cesarean section scars. A scheduled gravid hysterectomy was performed to complete the pregnancy termination and avoid recurrent uterine rupture. Pathological examination revealed marked attenuation and fibrosis of the anterior uterine wall with diffuse placenta accreta and focal placenta percreta justifying the decision for hysterectomy in this young patient. We therefore suggest that gravid hysterectomy rather than dilatation and evacuation should be considered for pregnancy termination in patients with history of recurrent uterine rupture and suspicion for abnormal placentation.     

Adaptation in adolescence: the influence of time and severe psychiatric disorder

This study reports the development of adaptive processes in two groups of adolescents assessed initially and 2 years later with clinical research interviews. Students from a public high school (N = 44) and inpatients on an adolescent psychiatric ward (N = 51) formed the two subject groups. The psychiatrically hospitalized group had significantly improved scores after a 2-year interval on four of six adaptive process Summary Scales: Task Orientation, Relatedness, Self Knowledge, and Inner Synthetic Functions. However, these higher scores did not reach the levels of the high school group at either point of assessment. The scores in the high school group remained stable over time except for an increase in the area of Self Knowledge. The value of this interview-derived assessment, in comparison to other forms of measurement, is discussed, and consideration is given to factors which contribute to the differences between groups.     

Increases in oxygen consumption without cerebral blood volume change during visual stimulation under hypotension condition.

The magnitude of the blood oxygenation level-dependent (BOLD) signal depends on cerebral blood flow (CBF), cerebral blood volume (CBV) and cerebral metabolic rate of oxygen (CMRO2). Thus, it is difficult to separate CMRO2 changes from CBF and CBV changes. To detect the BOLD signal changes induced only by CMRO2 responses without significant evoked CBF and CBV changes, BOLD and CBV functional magnetic resonance imaging (fMRI) responses to visual stimulation were measured under normal and hypotension conditions in isoflurane-anesthetized cats at 4.7 T. When the mean arterial blood pressure (MABP) decreased from 89+/-10 to 50+/-1 mm Hg (mean+/-standard deviation, n=5) by infusion of vasodilator sodium nitroprusside, baseline CBV in the visual cortex increased by 28.4%+/-8.3%. The neural activity-evoked CBV increase in the visual cortex was 10.8%+/-3.9% at normal MABP, but was negligible at hypotension. Positive BOLD changes of +1.8%+/-0.5% (gradient echo time=25 ms) at normal MABP condition became prolonged negative changes of -1.2%+/-0.3% at hypotension. The negative BOLD response at hypotension starts approximately 1 sec earlier than positive BOLD response, but similar to CBV change at normal MABP condition. Our finding shows that the negative BOLD signals in an absence of CBV changes are indicative of an increase in CMRO2. The vasodilator-induced hypotension model simplifies the physiological source of the BOLD fMRI signals, providing an insight into spatial and temporal CMRO2 changes.     

The impact of visuo-spatial number forms on simple arithmetic

Number forms, conscious visuo-spatial representations of the sequence of numbers, are found in around 12% of the population. However, their contribution to numerical cognition is not well understood. In this study we contrast the speeded performance of individuals with number forms versus controls on single digit multiplication, subtraction and addition. Previous research has suggested that multiplication may rely more on retrieval of verbal facts whereas subtraction relies more on online calculation using a putatively spatial ‘mental number line’. If people with number forms rely more heavily on visual-spatial strategies than verbal ones then we hypothesised that multiplication may be disproportionately affected by this strategy relative to subtraction, and this was found.     

Mucociliary clearance--a critical upper airway host defense mechanism and methods of assessment

PURPOSE OF REVIEW: Mucociliary clearance is a critical host defense mechanism of the airways. Effective mucociliary clearance requires appropriate mucus production and coordinated ciliary activity. The important role of these two components is best demonstrated in disorders such as primary ciliary dyskinesia and cystic fibrosis, both of which lead to lifelong recurrent respiratory tract infections. We review the methods used to analyze mucociliary clearance. RECENT FINDINGS: Utilization of microdialysis probes has improved temporal resolution of mucociliary clearance in murine airways, availing many genetic mouse models to critical mucociliary clearance analysis, while improved fixation technique for transmission electron microscopy has allowed for detailed resolution of the airway surface liquid. High-speed digital video analysis has improved quantification of ciliary beat frequency while advancements in air-liquid interface culturing techniques have generated in-vitro models to investigate mucociliary clearance. SUMMARY: Advancements in techniques for analysis of mucociliary clearance have improved our understanding of the interaction between the respiratory epithelium and the airway surface liquid, resulting in the ability to study pathologic processes involving mucociliary clearance in great detail.