A Novel Three-Dimensional-Printed Ultrasound-Guided Hip Arthrocentesis Model.

When evaluating patients with hip pain, clinicians may be trained to both evaluate for a hip effusion and perform ultrasound-guided arthrocentesis to evaluate the etiology of the effusion. We present a novel 3-dimensional-printed hip arthrocentesis model, which can be used to train clinicians to perform both tasks under ultrasound guidance. Our model uses a combination of a 3-dimensional-printed hip joint, as well as readily available materials such as an infant Ambu (Ballerup, Denmark) bag, syringe, intravenous line kit, and silicone. We present our experience so that others may use and adapt our model for their training purposes.

Transcription of the immediate-early gene Arc in CA1 of the hippocampus reveals activity differences along the proximodistal axis that are attenuated by advanced age.

The CA1 region of the hippocampus receives distinct patterns of afferent input to distal (near subiculum) and proximal (near CA2) zones. Specifically, distal CA1 receives a direct projection from cells in the lateral entorhinal cortex that are sensitive to objects, whereas proximal CA1 is innervated by cells in the medial entorhinal cortex that are responsive to space. This suggests that neurons in different areas along the proximodistal axis of CA1 of the hippocampus will be functionally distinct. The current experiment investigated this possibility by monitoring behavior-induced cell activity across the CA1 axis using Arc mRNA imaging methods that compared adult and old rats in two conditions: (1) exploration of the same environment containing the same objects twice (AA) or (2) exploration of two different environments that contained identical objects (AB). The hypothesis was that CA1 place cells should show field remapping in the condition in which environments were changed, but the extent of remapping was expected to differ between proximal and distal regions and between age groups. In fact, neurons in the proximal region of CA1 in adult animals exhibited a greater degree of remapping than did distal CA1 cells when the environment changed, suggesting that cells receiving input from the medial entorhinal cortex are more sensitive to spatial context. However, in old rats, there were no differences in remapping across the proximodistal CA1 axis. Together, these data suggest that distal and proximal CA1 may be functionally distinct and differentially vulnerable to normative aging processes.

Prenatal protein malnutrition alters the proportion but not numbers of parvalbumin-immunoreactive interneurons in the hippocampus of the adult Sprague-Dawley rat.

Prenatal protein malnutrition alters the structure and function of the adult rat hippocampal formation. The current study examines the effect of prenatal protein malnutrition on numbers of parvalbumin-immunoreactive (PV-IR) GABAergic interneurons, which are important for perisomatic inhibition of hippocampal pyramidal neurons. Brain sections from prenatally protein malnourished and normally nourished rats were stained for parvalbumin and PV-IR neurons were quantified using stereology in the dentate gyrus, CA3/2 and CA1 subfields, and the subiculum for both cerebral hemispheres. Results demonstrated that prenatal malnutrition did not affect the number of PV-IR interneurons in the hippocampus. Since prenatal protein malnutrition reduces total neuron numbers in the CA1 subfield (1), this results in an altered ratio of PV-IR interneurons to total neuronal numbers (from 1:22.9 in controls to 1:20.5 in malnourished rats). Additionally, there was no hemispheric asymmetry of either PV-IR neuron numbers or ratio of PV-IR:total neuron numbers.

Neurobiological changes in the hippocampus during normative aging.

The number of individuals older than 65 years is projected to exceed 71.5 million in the year 2030, which is twice the number alive during the year 2000. While this dramatic increase in the number of individuals at risk for Alzheimer and vascular disease will pose a significant challenge to the health care industry, many older individuals will not actually die of these age-related dementias. Instead, a significant proportion of those older than 65 years will have to cope with alterations in memory function that are associated with normative aging. A clear understanding of the neurobiological mechanisms underlying normal age-related changes will be essential in helping elderly populations maintain cognitive performance with increasing age. This review covers the major age-related alterations in the hippocampus, a critical structure for learning and memory.

Asymmetry of neuron numbers in the hippocampal formation of prenatally malnourished and normally nourished rats: a stereological investigation.

There is considerable evidence for lateralization of hippocampal function and hemispheric asymmetry in humans. In the rat, studies have reported asymmetries in the thicknesses of layers, the volumes of hippocampal subfields, and the density of cells at specific points along the septotemporal axis. To determine if there is an asymmetry of neuron numbers and whether prenatal malnutrition affects any asymmetries, 90-day old male Sprague-Dawley rats that were either normally nourished or malnourished prenatally were perfused with 4% paraformaldehyde and the brains cut into 30-micro m sections. One interrupted series of sections through the entire hippocampus was analyzed stereologically to estimate the total number of neurons in the hilus of the dentate gyrus, the CA3/CA2 stratum pyramidale (SP), the CA1 SP, and the SP of the prosubiculum/subiculum of both hemispheres. Significant asymmetries (P < 0.05) were found in the CA1 and CA3/CA2 subfields, with the right hemisphere containing 21 and 6% fewer neurons, respectively. Malnutrition reduced neuron numbers in the CA1 subfield by 12%, but did not alter the hemispheric asymmetry. Our findings agree with previous reports of left dominant asymmetries in the rat brain and suggest that this may result from differences in total numbers of neurons.

Effect of prenatal protein malnutrition on numbers of neurons in the principal cell layers of the adult rat hippocampal formation.

Malnutrition has been associated with a variety of functional and anatomical impairments of the hippocampal formation. One of the more striking of these is widespread loss of hippocampal neurons in postnatally malnourished rats. In the present study we have investigated the effect of prenatal malnutrition on these same neuronal populations, neurons that are all generated during the period of the dietary restriction. In prenatally protein deprived rats, using design-based stereology, we have measured the regional volume and number of neurons in the hilus of the dentate gyrus and the pyramidal cell layers of CA3, CA2, CA1, and the subiculum of 90-day-old animals. These results demonstrated a statistically significant reduction of 20% in neuron numbers in the CA1 subfield, while numbers in the other subfields were unchanged. There was a corresponding significant reduction of 22% in the volume of the CA1 subfield and a significant 14% decrease in the volume of the pyramidal layer of the subiculum. The change in volume of the pyramidal layer of the subiculum without neuron loss may reflect loss of CA1 afferent input to the pyramidal layer. Although the effect of nutritional deprivation on the neuronal population appears to be different in pre- and postnatal malnutrition, both dietary paradigms highlight the vulnerability of key components of the hippocampal trisynaptic circuit (consisting of the dentate granule cell mossy fibers projection to CA3 pyramids and the CA3 projection to the CA1 pyramids), which is an essential circuit for memory and learning.

Prenatal protein malnutrition in rats alters the c-Fos response of neurons in the anterior cingulate and medial prefrontal region to behavioral stress.

Prenatal protein malnutrition affects brain development and behavior despite dietary rehabilitation from birth. Behavioral alterations include abnormal responses to stressors. To explore what brain regions mediate this altered response, we used immunocytochemistry to c-Fos protein, a transcription factor marking neuronal activation. Controls (25% casein diet) and prenatally malnourished (6% casein) adult rats were subjected to 20min of restraint stress or were unstressed. Plasma corticosterone levels were monitored before and after stress. Paired comparisons of corticosterone levels confirmed that both groups showed a significant post-stress increase. Three hours after onset of stress, rats were perfused with paraformaldehyde. Brain sections were immuno-stained together for c-Fos. Since anterior cingulate and medial prefrontal cortex modulate stress responses, labeled neurons in this region were quantified using unbiased stereology. A 2-way ANOVA of neuron numbers demonstrated a strong effect of stress and a stress by nutrition interaction. Post-hoc comparisons showed that stress significantly increased the number of c-Fos labeled neurons in both nutrition groups. Within the stress condition, prenatally malnourished rats showed a significantly greater number of c-Fos positive neurons than well-nourished rats. These results suggest that neurons in anterior cingulate and medial prefrontal regions respond excessively to restraint stress in prenatally malnourished rats.