Intra-Tumoral Nerve-Tracing in a Novel Syngeneic Model of High-Grade Serous Ovarian Carcinoma

Dense tumor innervation is associated with enhanced cancer progression and poor prognosis. We observed innervation in breast, prostate, pancreatic, lung, liver, ovarian, and colon cancers. Defining innervation in high-grade serous ovarian carcinoma (HGSOC) was a focus since sensory innervation was observed whereas the normal tissue contains predominantly sympathetic input. The origin, specific nerve type, and the mechanisms promoting innervation and driving nerve-cancer cell communications in ovarian cancer remain largely unknown. The technique of neuro-tracing enhances the study of tumor innervation by offering a means for identification and mapping of nerve sources that may directly and indirectly affect the tumor microenvironment. Here, we establish a murine model of HGSOC and utilize image-guided microinjections of retrograde neuro-tracer to label tumor-infiltrating peripheral neurons, mapping their source and circuitry. We show that regional sensory neurons innervate HGSOC tumors. Interestingly, the axons within the tumor trace back to local dorsal root ganglia as well as jugular-nodose ganglia. Further manipulations of these tumor projecting neurons may define the neuronal contributions in tumor growth, invasion, metastasis, and responses to therapeutics.

Sight and switch off: Nerve density visualization for interventions targeting nerves in prostate cancer

Nerve density is associated with prostate cancer (PCa) aggressiveness and prognosis. Thus far, no visualization methods have been developed to assess nerve density of PCa in vivo. We compounded propranolol-conjugated superparamagnetic iron oxide nerve peptide nanoparticles (PSN NPs), which achieved the nerve density visualization of PCa with high sensitivity and high specificity, and facilitated assessment of nerve density and aggressiveness of PCa using magnetic resonance imaging and magnetic particle imaging. Moreover, PSN NPs facilitated targeted therapy for PCa. PSN NPs increased the survival rate of mice with orthotopic PCa to 83.3% and decreased nerve densities and proliferation indexes by more than twofold compared with the control groups. The present study, thus, developed a technology to visualize the nerve density of PCa and facilitate targeted neural drug delivery to tumors to efficiently inhibit PCa progression. Our study provides a potential basis for clinical imaging and therapeutic interventions targeting nerves in PCa.

Determination of optical properties of human tissues obtained from parotidectomy in the spectral range of 250 to 800 nm

The optical properties of human tissues are an important parameter in medical diagnostics and therapy. The knowledge of these parameters can encourage the development of automated, computer-driven optical tissue analysis methods. We determine the absorption coefficient μa and scattering coefficient μ s ' of different tissue types obtained during parotidectomy in the wavelength range of 250 to 800 nm. These values are determined by high precision integrating sphere measurements in combination with an optimized inverse Monte Carlo simulation. To conserve the optical behavior of living tissues, the optical spectroscopy measurements are performed immediately after tissue removal. Our study includes fresh samples of the ear, nose, and throat (ENT) region, as muscle tissue, nervous tissue, white adipose tissue, stromal tissue, parotid gland, and tumorous tissue of five patients. The measured behavior of adipose corresponds well with the literature, which sustains the applied method. It is shown that muscle is well supplied with blood as it features the same characteristic peaks at 430 and 555 nm in the absorption curve. The parameter μ s ' decreases for all tissue types above 570 nm. The accuracy is adequate for the purposes of providing μa and μ s ' of different human tissue types as muscle, fat, nerve, or gland tissue, which are embedded in large complex structures such as in the ENT area. It becomes possible for the first time to present reasonable results for the optical behavior of human soft tissue located in the ENT area and in the near-UV, visual, and near-infrared areas.

Nile Red derivatives enable improved ratiometric imaging for nerve-specific contrast

Surgical nerve damage due to difficulty with identification remains a major risk for postsurgical complications and decreased quality of life. Fluorescence-guided surgery offers a means to specifically highlight tissues of interest such as nerves and a number of fluorescence-guided surgical systems are in clinical trial or are approved for clinical use. However, no clinically approved nerve-specific fluorophores exist. In addition, many preclinical nerve-specific fluorophores tend to accumulate in adipose tissue due to the molecular composition similarities between the two tissues, making it challenging to generate a specific nerve signal. To alleviate this difficulty, we have synthesized a library of oxazine fluorophores based on the Nile Red scaffold, with the goal of strong adipose specificity without nerve uptake to facilitate ratiometric imaging. The library was screened for tissue specificity ex vivo and in vivo, enabling quantification of adipose-, nerve- and muscle-specific uptake as well as selection of the best candidate for adipose selectivity without nerve signal. We showed our selected Nile Red fluorophore improved nerve contrast using ratiometric imaging, especially nerve-to-adipose contrast as compared to the parent Nile Red compound or nerve-specific imaging alone. This adipose-specific Nile Red derivative could be used in future fluorescence-guided surgery applications where adipose- or nerve-specific contrast is required.

Functional magnetic resonance electrical impedance tomography (fMREIT) sensitivity analysis using an active bidomain finite-element model of neural tissue

PURPOSE

A direct method of imaging neural activity was simulated to determine typical signal sizes.

METHODS

An active bidomain finite-element model was used to estimate approximate perturbations in MR phase data as a result of neural tissue activity, and when an external MR electrical impedance tomography imaging current was added to the region containing neural current sources.

RESULTS

Modeling-predicted, activity-related conductivity changes should produce measurable differential phase signals in practical MR electrical impedance tomography experiments conducted at moderate resolution at noise levels typical of high field systems. The primary dependence of MR electrical impedance tomography phase contrast on membrane conductivity changes, and not source strength, was demonstrated.

CONCLUSION

Because the injected imaging current may also affect the level of activity in the tissue of interest, this technique can be used synergistically with neuromodulation techniques such as deep brain stimulation, to examine mechanisms of action.

Automatic segmentation of nerve structures in ultrasound images using Graph Cuts and Gaussian processes

Peripheral Nerve Blocking (PNB), is a procedure used for performing regional anesthesia, that comprises the administration of anesthetic in the proximity of a nerve. Several techniques have been used with the purpose of locating nerve structures when the PNB procedure is performed: anatomical surface landmarks, elicitation of paresthesia, nerve stimulation and ultrasound imaging. Among those, ultrasound imaging has gained great attention because it is not invasive and offers an accurate location of the nerve and the structures around it. However, the segmentation of nerve structures in ultrasound images is a difficult task for the specialist, since such images are affected by echo perturbations and speckle noise. The development of systems for the automatic segmentation of nerve structures can aid the specialist for locating nerve structures accurately. In this paper we present a methodology for the automatic segmentation of nerve structures in ultrasound images. An initial step is carried out using Graph Cut segmentation in order to generate regions of interest; we then use machine learning techniques with the aim of segmenting the nerve structure; here, a specific non-linear Wavelet transform is used for the feature extraction stage, and Gaussian processes for the classification step. The methodology performance is measured in terms of accuracy and the dice coefficient. Results show that the implemented methodology can be used for automatically segmenting nerve structures.

IMAGING OF NEURO-INFLAMMATION: PAST, PRESENT AND FUTURE

The investigation of dynamic processes with long time profiles can profit from longitudinal noninvasive imaging modalities. In this contribution the potential and limits of in vivo imaging modalities are discussed as regards monitoring neuro-inflammation. Complementary information derived from magnetic resonance imaging (MRI), positron emission tomography (PET) and bioluminescence imaging (BLI) will be presented.

Scanning electron microscopy of fetal murine myelomeningocele reveals growth and development of the spinal cord in early gestation and neural tissue destruction around birth

BACKGROUND

Previous studies demonstrated that the spinal cord within a fetal myelomeningocele (MMC) lesion suffers progressive destruction during gestation. This study aims at elucidating this pathophysiologic feature on a cellular and ultrastructural level in a model of genetically determined MMC.

METHODS

Curly tail/loop tail mouse fetuses at various gestational stages and neonates were analyzed electron-microscopically to document time-point and nature of neural tissue development and pathologic alterations within the MMC.

RESULTS

At embryonic day (E) 8.5 and E9.5, round cells displaying multiple microvilli covered the entire region of interest, and some specimens showed initial stages of neurulation. At E10.5, neurulation was terminated in normal animals, whereas the neural placode remained unfolded in MMC fetuses and became distinguishable from adjacent epidermal layers. At E15.5, an apparently normal differentiation was found. Until this time-point, there was no tissue damage or inflammation. Thereafter, increasingly severe tissue alterations were identified with ongoing gestation leading to almost complete loss of neural tissue at birth.

CONCLUSION

We show here in fetal mice with MMC that, apart from absent neurulation, growth and development of the otherwise perfectly intact exposed spinal cord appear normal in early gestation, whereas later, the unprotected neural tissue is progressively destroyed.

Positron emission tomography imaging of transplant function

In this article, the role of functional imaging for providing objective evidence that grafts of fetal tissue can survive and form connections in Parkinson's and Huntington's disease patients is reviewed. The dissociation between dopamine storage capacity, clinical improvement, and normalization of brain metabolism in PD is discussed, and possible mechanisms underlying the phenomenon of dyskinesias off medication are presented. It is concluded the positron emission tomography and single photon emission computed tomography can provide valuable ancillary information alongside clinical observations but are not currently appropriate modalities for use as surrogate endpoints.

Ultrasound of nerve and muscle

Over the last two decades, ultrasound has developed into a useful technology for the evaluation of diseases of nerve and muscle. Since it is currently not used at by the majority of clinicians involved in diagnosis or care of patients with neuromuscular disorders, this review briefly describes the technical aspects of ultrasound and its physical principles. It relates normal muscle anatomy and movement to ultrasound images in the axial and sagittal planes and follows with a discussion of ultrasound findings in chronic muscle disease. These include evident atrophy and the loss of the hypoechoic architecture of normal muscle tissue. It highlights evolving uses of the technique to measure other pathologic changes in disease including altered muscle dynamics. With high-resolution instruments nerve imaging has now become standard, and the relationships of median nerve anatomy and observations of static and dynamic images from ultrasound are reviewed. Changes seen in carpal tunnel syndrome include significant increases in the cross-sectional area of the nerve just proximal to the site of compression, loss of hyperechoic intensities within nerve, and reduced mobility. Preliminary use of the technique for the study of other nerves is reviewed as well. Ultrasound is an ideal tool for the clinical and research investigation of normal and diseased nerve and muscle complementary to existing diagnostic techniques. As the technology continues to evolve, it will likely assume a more significant role in these areas as those most able to exploit its potential, clinical neurophysiologists and neuromuscular clinicians, incorporate its use at the bedside.

Chapter 25 Imaging nerve and muscle with ultrasound

Over the last two decades significant advances in ultrasound have made it possible for investigators to image and interpret pathologic changes in muscle and nerve. In addition to being able to assess the pathologic changes in these structures themselves, ultrasound also provides the unique ability to identify anatomic lesions responsible for nerve or muscle injury. They can be correlated with changes in neural structures or affected muscles. Like electrodiagnostic studies, ultrasound is portable and inexpensive, but it is even less invasive, and surprisingly sensitive in detecting a variety of unusual and common causes of neuromuscular dysfunction. Given recent developments in the field, ultrasound shows promise as the technique most suitable for clinical neurophysiologists and neuromuscular clinicians in the growing field of imaging. Such involvement is required to best adopt and exploit the potential of imaging for the research and clinical evaluation of neuromuscular disorders.

Pyridoxine-dependent seizures associated with white matter abnormalities

Pyridoxine-dependent seizures are a disorder of GABA metabolism probably due to a defective binding of pyridoxal phosphate coenzyme (PALP) with glutamate decarboxylase (GAD), the rate-limiting enzyme in GABA synthesis. The resulting GABA deficiency causes severe epilepsy in infancy. We report on a boy with seizures starting soon after birth, and only controlled by pyridoxine at pharmacological dosages. After two months without seizures, a CT scan showed hypodense white matter in frontal and occipital lobes suggestive of a retarded or defective myelination. We are not aware of other descriptions of such morphological abnormalities in a patient with this disorder.

[Multiple hemorrhagic cerebral amyloid angiopathy associated with leukoencephalopathy]

The authors present a case of cerebral amyloid angiopathy (CAA) which caused multiple recurrent subcortical hemorrhages and leukoencephalopathy similar to Binswanger's disease. CT scan revealed bilateral hypodensity of the hemispheric white matter in addition to multiple subcortical hemorrhages. The difference between white and gray matter densities was 14 approximately 15 HU. T2-weighted MRI showed the hemispheric white matter as high intensity. These findings on CT and MRI are compatible with those observed in leukoencephalopathy like Binswanger's disease. A biopsy of the cortex was performed and histological examination revealed amyloid deposition in the arterial wall. In addition to amyloid deposition, obliterative intimal proliferation and hyaline degeneration of the vessel were observed. It is thought that the occlusive vascular change due to CAA may induce chronic hypoperfusion of the hemispheric white matter and consequently the leukoencephalopathy may develop. In the aged population, CAA is noteworthy as a cause of both hemorrhagic and ischemic lesions, because the incidence of CAA is increasing with age.

[Computed tomography of Creutzfeldt-Jakob disease]

Creutzfeldt-Jakob disease (CJD), one of the transmissible spongiform encephalopathy, affects gray matter primarily. Degeneration of the white matter is uncommon and when it occurs is usually mild, and limited in distribution. Mizutani separated the "panencephalopathic type" of CJD from the other type, because this panencephalopathic type has extensive white matter changes, that could not be explained simply as secondary to cortical degeneration. This communication discusses six necropsy cases of CJD. In four cases of panencephalopathic type, out of our cases, there were extensive changes of cerebral white matter in addition to severe loss of neurons and hypertrophic astrogliosis in cortex and basal ganglia. Computed tomography demonstrated diffuse low attenuation areas in the white matter with marked atrophy of the cortex, brainstem and cerebellum.

Perineural spread of nasopharyngeal carcinoma: radiological and CT demonstration

Perineural spread is well known to be the most insidious form of tumour spread of a number of head and neck malignancies. However, perineural extension of nasopharyngeal carcinoma (NC) is a poorly recognized event. Four cases of perineural metastases from NC have been detected with pluridirectional tomography and CT. In 3 cases involvement of the Vidian nerve (nervus canalis pterygoidei) and pterygoid canal was observed. In a fourth patient, invasion of one pterygopalatine fossa and perineural spread along ipsilateral maxillary nerve with enlargement and erosion of the foramen rotundum was demonstrated. Radiological diagnosis of clinically unsuspected perineural tumour spread is important because it markedly influences treatment planning and prognosis of NC.