Prehospital emergency inguinal clamp controls hemorrhage in cadaver model.

BACKGROUND: The Combat Ready Clamp is indicated to stop difficult inguinal bleeding on the battlefield, the most common type of junctional bleeding and now the most common cause of preventable battlefield death. The purpose of the present study is to report the data of clamp development to help appliers use it correctly. METHODS: Wake Forest University investigators used a cadaver model to test the clamp's ability to control hemorrhage. Ten fresh cadavers were made to simulate inguinal and popliteal wound bleeding. Blood simulant was pumped to quantify device effectiveness in testing. Points of application included proximal pressure point control of popliteal, inguinal, and bilateral bleeding. RESULTS: Clamp use promptly controlled pulsing arterial hemorrhages from inguinal, popliteal, and bilateral wounds. The device, when placed on the common iliac artery, stopped all ipsilateral distal bleeding. CONCLUSIONS: The evidence of how the clamp works in the cadaver model showed that clamp use can plausibly be tailored to control inguinal hemorrhage from one wound, control two ipsilateral wounds with hemorrhage from one artery (e.g., common iliac artery), and control bilateral inguinal wounds (compression of the origins of bilateral common iliac arteries).

Creating interactive learning objects with PowerPoint: primer for lecture on the autonomic nervous system.

BACKGROUND: In medical curricula, difficult topics are often presented to students with varied backgrounds and therefore at different levels of preparation to learn and assimilate the information. AIM: A method is described to create an interactive primer for the study of a basic neuroscience topic to improve student preparation for and understanding of the autonomic nervous system. METHODS: Action buttons or links within a PowerPoint show were used to create an interactive show. Branch points were imposed, as students answered questions correctly or incorrectly. In this way, the learning path was individualized depending on the level of comprehension. RESULTS: Response to the interactive learning objects has been favorably received by the students with very favorable scores on the end-of-course evaluation. Preliminary analysis of the benefit of the interactive primer on summative examination suggests modest improvement on more difficult questions. CONCLUSIONS: Use of the primer on the autonomic nervous system is discussed in the context of reports on the effectiveness of other blended learning and interactive learning experiences. The interactive tool described requires little facility with or support for web-based programming by faculty, and can be streamlined by creation of a PowerPoint template with pre-set interaction buttons.

Anterior hippocampal volume is reduced in behaviorally depressed female cynomolgus macaques.

Hippocampal (HC) function and morphology have been implicated in the pathophysiology of depression. Reduced HC volume has been observed in depressed humans, although the effect is not always significant. Studies of functional differentiation of the HC have revealed that the anterior portion is associated with emotional and anxiety-related functioning, and the posterior portion with memory processing. As such, measuring whole HC volume may mask differences seen only in the anterior or posterior HC. We used unbiased stereology to measure whole, anterior, and posterior HC volumes in 12 adult female cynomolgus macaques, half of which exhibited spontaneously occurring depressive behavior defined as a slumped/collapsed body posture with open eyes, and a relative lack of responsivity to environmental stimuli. The two groups were otherwise matched on circulating estradiol, progesterone, and cortisol levels, social status, estimated age, and body weight. Frozen postmortem HC tissue from depressed and nondepressed monkeys was serially sectioned and thionin-stained. According to established neuroanatomical guidelines and with the aid of Neurolucida software (MBF Bioscience), every 10th section throughout the extent of the HC was manually traced and used to reconstruct the 3D models used to determine volumes. Anterior and posterior HC were delineated by the presence or absence of the uncus. No significant differences were found between depressed and nondepressed monkeys for whole or posterior HC volume, although the average HC volume was 4% smaller in depressed than nondepressed monkeys. Anterior HC volumes were significantly smaller (15.4%) in depressed compared to nondepressed monkeys. These results indicate that reduced volume in the anterior HC, an area previously implicated in emotional functioning, may be associated with a depressive phenotype in female cynomolgus macaques.

Rapid modifications in calretinin immunostaining in the deep layers of the superior colliculus after unilateral cochlear ablation.

Calretinin (CR) is a calcium-binding protein that plays an important role in the homeostasis of intracellular calcium concentration in the auditory pathway. To test if hearing loss could lead indirectly to modifications in levels of this calcium-binding protein in neurons and neuropilar structures outside of the lemniscal auditory pathway, CR-immunostaining was evaluated in the superior colliculus (SC) in adult ferrets at 1, 20 and 90 days after unilateral cochlear ablation. The results demonstrate that within 24h there was a significant increase in CR-immunostaining in ablated animals as indicated by an increase in the mean gray level of immunostaining in the deep, multisensory layers of the contralateral SC compared to the ipsilateral side and control ferrets. This upregulation was evident in both neurons and neuropil and did not change at the two subsequent time points. In contrast, there was no change in the superficial layers of the SC which have visual properties but no auditory inputs. These findings suggest that upregulation of CR levels within neurons and neuropil in the contralateral deep SC is subject to modifications by activity in multisynaptic auditory pathways. Therefore, cochlear-driven activity appears to affect calcium-binding protein levels not only in auditory nuclei but also in other neural structures whose response properties may be influenced by auditory-related activity.

Early segregation of layered projections from the lateral superior olivary nucleus to the central nucleus of the inferior colliculus in the neonatal cat.

The central nucleus of the inferior colliculus (IC) is a laminated structure that receives multiple converging afferent projections. These projections terminate in a layered arrangement and are aligned with dendritic arbors of the predominant disc-shaped neurons, forming fibrodendritic laminae. Within this structural framework, inputs terminate in a precise manner, establishing a mosaic of partially overlapping domains that likely define functional compartments. Although several of these patterned inputs have been described in the adult, relatively little is known about their organization prior to hearing onset. The present study used the lipophilic carbocyanine dyes DiI and DiD to examine the ipsilateral and contralateral projections from the lateral superior olivary (LSO) nucleus to the IC in a developmental series of paraformaldehyde-fixed kitten tissue. By birth, the crossed and uncrossed projections had reached the IC and were distributed across the frequency axis of the central nucleus. At this earliest postnatal stage, projections already exhibited a characteristic banded arrangement similar to that described in the adult. The heaviest terminal fields of the two inputs were always complementary in nature, with the ipsilateral input appearing slightly denser. This early arrangement of interdigitating ipsilateral and contralateral LSO axonal bands that occupy adjacent sublayers supports the idea that the initial establishment of this highly organized mosaic of inputs that defines distinct synaptic domains within the IC occurs largely in the absence of auditory experience. Potential developmental mechanisms that may shape these highly ordered inputs prior to hearing onset are discussed.

Synaptophysin and insulin-like growth factor-1 immunostaining in the central nucleus of the inferior colliculus in adult ferrets following unilateral cochlear removal: a densitometric analysis.

In the present study, unilateral cochlear ablations were performed in adult ferrets to evaluate possible time-dependent modifications of synaptophysin and insulin-like growth factor-1 (IGF-1) in the central nucleus of the inferior colliculus (CNIC). Using densitometric analysis, synaptophysin and IGF-1 immunostaining were assessed at 1 (PA1) and 90 (PA90) days after cochlear ablation. The results demonstrated that 1 day after the lesion there was an increase in the levels of synaptophysin immunostaining bilaterally in the CNIC compared to control animals. That increase was no longer present at 90 days after the ablation. Overall levels of IGF-1 immunostaining at PA1 were increased significantly within neurons and neuropil. However, at PA90, only IGF-1 immunostaining contralateral to the lesion was elevated compared to control animals, although elevation was less than that observed at PA1. These results suggest that cochlear ablation appears to affect synaptophysin and IGF-1 protein levels bilaterally in the CNIC.

Synaptogenesis in the inferior colliculus of the pre-hearing postnatal ferret.

Although intrinsic organization in the inferior colliculus (IC) has been surveyed in a variety of species, current knowledge of synaptogenesis within the mammalian inferior colliculus is limited. The present study surveyed the ultrastructure of the central nucleus of the inferior colliculus in postnatal day (P) P4, P7, P14, and P28 ferrets, prior to the onset of hearing at the end of the first postnatal month with the goal of beginning to characterize the time course of synapse formation in relation to the development of afferent projection patterns within the IC. Results suggest that initial synaptogenesis has occurred in the IC by P4 and continues during the period when maturation of the distribution of axons from brainstem auditory nuclei is taking place.

Quantitative changes in calretinin immunostaining in the cochlear nuclei after unilateral cochlear removal in young ferrets.

Neurons of the cochlear nuclei receive axosomatic endings from primary afferent fibers from the cochlea and have projections that diverge to form parallel ascending auditory pathways. These cells are characterized by neurochemical phenotypes such as levels of calretinin. To test whether or not early deafferentation results in changes in calretinin immunostaining in the cochlear nucleus, unilateral cochlear ablations were performed in ferrets soon after hearing onset (postnatal day [P]30-P40). Two months later, changes in calretinin immunostaining as well as cell size, volume, and synaptophysin immunostaining were assessed in the anteroventral (AVCN), posteroventral (PVCN), and dorsal cochlear nucleus (DCN). A decrease in calretinin immunostaining was evident ipsilaterally within the AVCN and PVCN but not in the DCN. Further analysis revealed a decrease both in the calretinin-immunostained neuropil and in the calretinin-immunostained area within AVCN and PVCN neurons. These declines were accompanied by significant ipsilateral decreases in volume as well as neuron area in the AVCN and PVCN compared with the contralateral cochlear nucleus and unoperated animals, but not compared with the DCN. In addition, there was a significant contralateral increase in calretinin-immunostained area within AVCN and PVCN neurons compared with control animals. Finally, a decrease in area of synaptophysin immunostaining in both the ipsilateral AVCN and PVCN without changes in the number of boutons was found. The present data demonstrate that unilateral cochlear ablation leads to 1) decreased immunostaining of the neuropil in the AVCN and PVCN ipsilaterally, 2) decreased calretinin immunostaining within AVCN and PVCN neurons ipsilaterally, 3) synaptogenesis in the AVCN and PVCN ipsilaterally, and 4) increased calretinin immunostaining within AVCN and PVCN neurons contralaterally.

Alterations in calretinin immunostaining in the ferret superior olivary complex after cochlear ablation.

In this study, we used image analysis to assess changes in calretinin immunoreactivity in the lateral (LSO) and medial (MSO) superior olivary nuclei in ferrets 2 months after unilateral cochlear ablations at 30-40 days of age, soon after hearing onset. These two nuclei are the first significant sites of binaural convergence in the ascending auditory system, and both receive direct projections from the deafferented cochlear nucleus. Cochlear ablation results in a decrease in the overall level of calretinin immunostaining within the LSO ipsilaterally compared with the contralateral side and with control animals and within the MSO bilaterally compared with control ferrets. In addition, the level of calretinin immunostaining ipsilaterally within neurons in the LSO was significantly less in cochlear ablated than control animals. In contrast, there was no effect of cochlear ablation on the level of calretinin immunostaining within neurons either in the contralateral LSO or in the MSO. These results are consistent with a downregulation in calretinin within the neuropil of MSO bilaterally and LSO ipsilaterally, as well as a downregulation in calretinin within somata in the ipsilateral LSO as a result of unilateral cochlear ablation soon after hearing onset. Thus, cochlear-driven activity appears to affect calcium binding protein levels in both neuropil and neurons within the superior olivary complex.

Upregulation of calretinin immunostaining in the ferret inferior colliculus after cochlear ablation.

In many systems, including ascending auditory pathways, calcium-binding proteins are markers of specific neuronal circuits. Previous studies suggest that calretinin immunostaining may be a specific marker for circuits in the inferior colliculus (IC) that code timing information. We undertook experiments to determine the changes in calretinin immunostaining in the IC that take place in response to cochlear ablation. Cochlear ablation was performed unilaterally in ferrets just after hearing onset. Animals survived for 2-3 months after ablation and brains were then processed for calretinin immunocytochemistry. The mean optical density and stained area of the calretinin immunopositive plexus in the IC were determined for five coronal sections through the right and left IC. In controls (n = 3), measurements of these parameters in the central nucleus of the IC showed symmetry between the two sides. In experimental animals (n = 8) the calretinin immunopositive plexus contralateral to the cochlear ablation was denser and larger than that in either the ipsilateral IC or in the IC of control animals. The calretinin plexus in the ipsilateral IC was slightly less dense and smaller than in controls but the differences did not reach statistical significance. IC volume measurements and synaptophysin immunostaining analysis in the central nucleus of the IC revealed no statistical differences between ablated and control animals or between the two sides in ablated animals. The significant increase in both mean optical density and immunostained area of the calretinin plexus in the IC contralateral to the cochlear ablation may reflect an upregulation in calretinin expression in the nuclei that contribute to this plexus.

Quantitative measurement of afferent layers in the ferret inferior colliculus: DNLL projections to sublayers.

In the central nucleus of the inferior colliculus (IC), afferent projections are aligned with dendritic arbors of disk-shaped cells, forming fibrodendritic layers. One feature that may serve as a guide for study of the intrinsic organization of the IC layers is the segregation of certain inputs to bands and patches within the layers of the central nucleus. In this study, we used Phaseolus leucoagglutinin as an anterograde tracer to examine the projections from the dorsal nucleus of the lateral lemniscus to the contralateral IC in adult ferrets. The labeled afferent projections distributed along the IC layers in a series of bands where there were dense endings and interband spaces where there were few if any endings. Branches of individual labeled axons that were reconstructed distributed within a single afferent band. Measurements of both the terminal density distribution and the optical density across the band were similar indicating that afferent bands were approximately 85 microm thick. Quantitative measurements of the labeled afferent bands will enhance comparison with other afferent projections and analysis of afferent development and plasticity.

Direct projections from cochlear nuclear complex to auditory thalamus in the rat.

It is known that the dorsal cochlear nucleus and medial geniculate body in the auditory system receive significant inputs from somatosensory and visual-motor sources, but the purpose of such inputs is not totally understood. Moreover, a direct connection of these structures has not been demonstrated, because it is generally accepted that the inferior colliculus is an obligatory relay for all ascending input. In the present study, we have used auditory neurophysiology, double labeling with anterograde tracers, and retrograde tracers to investigate the ascending projections of the cochlear nuclear complex. We demonstrate that the dorsal cochlear nucleus and the small cell cap of the ventral cochlear nucleus have a direct projection to the medial division of the medial geniculate body. These direct projections from the cochlear nucleus complex bypass the inferior colliculus and are widely distributed within the medial division of the medial geniculate, suggesting that the projection is not topographic. As a nonlemniscal auditory pathway that parallels the conventional auditory lemniscal pathway, its functions may be distinct from the perception of sound. Because this pathway links the parts of the auditory system with prominent nonauditory, multimodal inputs, it may form a neural network through which nonauditory sensory and visual-motor systems may modulate auditory information processing.