Rationale for the advancement of PI3K pathway inhibitors for personalized chordoma therapy.

PURPOSE: Chordomas are rare and serious tumors with few effective treatments outside of aggressive surgery and radiation. Targeted therapies may present a more effective option for a subset of patients with lesions possessing certain genetic biomarkers. METHODS: A small molecule inhibitor library was tested in patient-derived UM-Chor1 cells to identify targeted therapies with potential efficacy. Targeted exome sequencing of UM-Chor1 and UM-Chor2 cells was performed to investigate genetic aberrations in relevant pathways. Chordoma cell lines were treated with inhibitors of the phosphotidylinositol 3-kinase (PI3K), epidermal growth factor receptor (EGFR), and cyclin dependent kinase (CDK) pathways, and responses were determined using resazurin cell viability assays, Annexin V apoptosis assays, and western blotting. Pan-PI3K inhibitor BKM120 was also tested in five chordoma xenograft models. RESULTS: Unbiased small molecule profiling nominated PI3K-AKT-mTOR pathway inhibitors as a promising therapy in chordoma, and genetic analyses of UM-Chor1 and UM-Chor2 cell lines revealed aberrations in PTEN, EGFR, and CDKN2A. Treatment of UM-Chor1 and UM-Chor2 with targeted PI3K, EGFR, and CDK inhibitors inhibited growth and proliferation and induced apoptosis more robustly than imatinib, a currently used chordoma therapy. Furthermore, BKM120 significantly inhibited tumor growth in a subset of the xenograft models tested. CONCLUSION: Targeted therapies, especially those inhibiting PI3K, display promising effects in multiple chordoma cell line and xenograft models. Nevertheless, the limited effects of PI3K, EGFR, and CDK targeting agents in other models reveal the presence of resistance mechanisms, which motivates future research to both identify biomarkers of response and develop combination therapies.

Evaluation of CD44 variant expression in oral, head and neck squamous cell carcinomas using a triple approach and its clinical significance.

Cancer stem cells possess the qualities of self-renewal, tumorigenesis and the ability to recapitulate a heterogeneous tumor. Our group was the first to isolate head and neck squamous cell carcinoma (HNSCC) stem cells using the cell surface marker CD44. CD44 is a trans-membrane glycoprotein with a multitude of key-functions that regulate cancer cell proliferation and metastasis. The variety of CD44 functions is due to tissue-specific patterns of glycosylation of the extracellular portion, and to the multiple protein isoforms (CD44 variants, CD44v) generated by alternative splicing. This study investigates the expression pattern of CD44 variants in HNSCC. Ten cell lines from the most common HNSCC locations and representative of various clinical outcomes were assayed by quantitative realtime PCR, flow cytometry and immunofluorescence comparatively with normal oral keratinocytes. The CD44 v4 and v6 were exclusively abundant in HNSCC while the isoform v1,2 was expressed in normal oral keratinocytes. Of interest, the highest level of CD44v6 expression was detected in advanced metastatic HNSCC, suggesting a link between CD44v6 expression and HNSCC metastasis, while the highest CD44v4 was detected in a stage IV HNSCC refractory to chemotherapy which developed recurrence. Oral-derived HNSCC expressed the highest CD44v4 and v6, and levels corresponded with staging, showing also an increasing tendency with recurrence and metastasis. CD44v were detected predominantly in smaller cells (a characteristic that has been associated with stem cell properties) or cells with mesenchymal morphology (a characteristic that has been associated with the migratory and invasive potential of epithelial tumor cells), suggesting that CD44v differential expression in HNSCC may be representative of the morphological changes inherent during tumor progression towards a more aggressive potential, and thus contributing to the individual tumor biology. The mechanism of CD44 variant involvement in HNSCC progression and metastasis is under investigation.

Al-alkyls as acceptor dopant precursors for atomic-scale devices.

Atomically precise ultradoping of silicon is possible with atomic resists, area-selective surface chemistry, and a limited set of hydride and halide precursor molecules, in a process known as atomic precision advanced manufacturing (APAM). It is desirable to expand this set of precursors to include dopants with organic functional groups and here we consider aluminium alkyls, to expand the applicability of APAM. We explore the impurity content and selectivity that results from using trimethyl aluminium and triethyl aluminium precursors on Si(001) to ultradope with aluminium through a hydrogen mask. Comparison of the methylated and ethylated precursors helps us understand the impact of hydrocarbon ligand selection on incorporation surface chemistry. Combining scanning tunneling microscopy and density functional theory calculations, we assess the limitations of both classes of precursor and extract general principles relevant to each.

Participatory rural appraisal to investigate constraints in reporting cattle mortalities in the Odi district of North West Province, south Africa.

Mortalities in cattle can have severe financial implications for small scale and communal farmers in South Africa. They could also be a measurable indicator for surveillance of animal diseases, such as those listed by the Office International des Epizooties (OIE), or diseases included in the regulations of the South African Animal Diseases Act, 1984 (Act 35 of 1984). In order to prevent further mortalities and for accurate surveillance and monitoring of diseases, it is important that farmers participate in the determination of causes of mortality in their cattle. This paper reports on constraints of the reporting diseases to the state veterinary services, the study area being Odi district, in the North West Province. The method that was followed was based on participatory rural appraisal. The selected cattle owners participated in every phase. They were the ones who first spoke to veterinary services about ways to decrease the diseases and mortalities of their cattle. A questionnaire to verify the facts complemented the survey. A total number of 60 farmers were randomly selected from 12 villages. One farmer withdrew, leaving 59 farmers. Most of the farmers in the study were men ( n = 55). The area of study was communal and the farming system traditional and extensive. It was suspected that there was a communication problem and this was proven by the results of the research, as 23 farmers were not even aware that mortalities have to be reported by law. The real problem was that causes of death were not being diagnosed because farmers were not aware that a necropsy could give information on the causes of death. Farmers were keen to receive training in elementary necropsy techniques so as to be able to discuss the cause of death of cattle with the state veterinarian.

Targeting Head and Neck Cancer Stem Cells: Current Advances and Future Challenges.

Cancer stem cells (CSCs), or tumor-initiating cells, comprise a subset of tumor cells with demonstrated ability for tumor growth, invasion, metastasis, and resistance to chemotherapy and radiation. Targeting of CSCs remains an attractive yet elusive therapeutic option, with the goal of increasing specificity and effectiveness in tumor eradication, as well as decreasing off-target or systemic toxicity. Research into further characterization and targeted therapy toward head and neck CSCs is an active and rapidly evolving field. This review discusses the current state of research into therapy against head and neck CSCs and future directions for targeted therapy.

Acute effect of traction, compression, and hip joint tamponade on blood flow of the femoral head: an experimental model.

Blood flow rates of the canine femoral head were experimentally determined during traction, compression, and hip joint tamponade using the hydrogen washout technique. In puppies, blood flow rate of the femoral head was significantly decreased with either traction or compression applied at one half body weight. Either maneuver, when combined with hip joint tamponade, reduced blood flow rate of the femoral head an average of more than 70% as compared with the initial control rate. In adult dogs, combinations of either traction or compression, at one-half body weight, with hip joint tamponade did not significantly decrease blood flow rate of the femoral head as compared with control values. Perfusion defect of blue silicone could be observed only in puppies around the hip during combinations of traction or compression with hip joint tamponade and involved the posterior superior capital branches of the medial circumflex artery and the arteries in the ligamentum teres. These experimental data may have important implications for the pathogenesis of iatrogenic avascular necrosis in the treatment of congenitally dislocated hip, Legg-Perthes disease, and avascular necrosis following nondisplaced femoral neck fracture.

Intraoperative stimulation of the spinal cord for prevention of spinal cord injury.

There are several spinal cord stimulation methods available for eliciting an MEP. As with any procedure, there are strengths and weaknesses associated with each method that the examiner needs to become familiar with. Because each testing situation is different, a specific elicitation or recording technique may not be appropriate for all surgeries. For example, if tumor removal of the spinal cord is being performed, the examiner may wish to avoid using an EMG in order to eliminate the possibility of patient movement. Therefore, before initiating the use of any method for eliciting an MEP, it is the examiner's responsibility to become thoroughly familiar with the technique under consideration. Regarding the NMEP procedure, we feel very confident with this method for monitoring motor tract function. Although a "true" myogenic MEP is the preferred type of response to record, we believe that this response is too unreliable and insensitive for our use. We also believe that any weaknesses associated with the NMEP are more than offset by its strengths. In conclusion, the results from studies described in this chapter indicate that spinal cord stimulation does elicit an MEP. Based on the testing situation, either a myogenic or NMEP can be recorded and can provide the surgeon with information regarding motor tract function. However, it does not appear that information regarding total spinal cord function can be obtained by using only SEPs. In order to provide the surgeon with this information, an SEP and MEP method must be administered.

Relationship among level of distraction, evoked potentials, spinal cord ischemia and integrity, and clinical status in animals.

Somatosensory evoked potentials (SEPs) and neurogenic-motor evoked potentials (NMEPs) were recorded after overdistraction of the spinal cord at T5-T6, T12-L1, or L3-L4. Measures of spinal cord perfusion and clinical status were also administered. Results indicated that stiffer spinal segments allowed less distraction than more flexible segments. SEPs and NMEPs were lost quickly after overdistraction in stiff segments and slowly in more flexible segments. However, SEPs were less sensitive than NMEPs to effects from overdistraction. Spinal cord perfusion and integrity were consistent with reduced perfusion and structural damage after overdistraction in stiff segments; extremely reduced perfusion but no structural changes in more flexible segments. The application of these results to the clinical situation was provided.

Effects of compression on physiologic integrity of the spinal cord, on circulation, and clinical status in four different directions of compression: posterior, anterior, circumferential, and lateral.

The authors investigated the effects of focal compression on physiologic integrity; somatosensory evoked potentials, neurogenic motor evoked potentials and spine-to-spine potentials, on spinal cord circulation and clinical status in four different type of compression; posterior, anterior, circumferential, and lateral in 31 pigs. Spine-to-spine potentials degraded earlier in amplitude than somatosensory evoked and motor evoked potentials regardless of direction of compression. The first lost potential was the somatosensory evoked one during posterior, circumferential, and lateral compression and motor evoked potentials during anterior compression. Somatosensory evoked potential was the only wave to detect the side of lateral compression. Following release of compression somatosensory evoked potentials and motor evoked potentials returned almost to 100% in amplitude, whereas spine-to-spine potentials recovered to approximately 50%. At that time all animals showed grossly normal motion in hind-limb, therefore spine-to-spine potentials might be too sensitive to motor function. Spine-to-spine potentials should contain more tracts than either somatosensory evoked potentials or motor evoked potentials. Somatosensory evoked potentials probably show more posterior part, whereas motor evoked potentials do more of the anterior part of the spinal cord. The spinal cord revealed a complete ischemia regardless of direction of compression when at least one potential was gone, however it regained the shape and perfusion following release of compression although there were some hemorrhagic contusions remaining. These suggest that ischemic changes may play some part in degradation of potentials, however it does not influence much the recovery following release of compression because it regains quickly. The final recovery depends on the complication.

Relationship between duration of spinal cord ischemia and postoperative neurologic deficits in animals.

Twenty hogs were administered the following procedures before, during, and after overdistraction of the spinal column at T5-T6: somatosensory (SEP) and neurogenic-motor evoked potentials (NMEPs), hydrogen clearance procedures, Stagnara wake-up tests, and aortic-injection of silastic plastic. To ensure that overdistraction was possible, a nonosseous, circumferential osteotomy was made at T5-T6 and distraction applied in one-ratchet increments using Harrington instrumentation. Overdistraction was maintained for 3, 5, 6, 10, 15, 20, 25, or 30 minutes. Results indicated that the duration of overdistraction, as represented by lost NMEPs, was always correlated with the animal's clinical status on wake-up test. If overdistraction was maintained more than 6 minutes, 100% of the animals demonstrated positive wake-up results; if maintained between 5 and 6 minutes, 75% demonstrated positive wake-up results; and if maintained less than 5 minutes, only 25% demonstrated positive wake-up results. Time-to-loss of the NMEPs and SEPs, after onset of overdistraction, fell within two groups: slow and fast. In the slow group, it required slightly more than 20 minutes (mean = 20.6) for the potentials to be lost, while in the fast-loss group data were lost in slightly less than 4 minutes (mean = 3.6). Blood flow studies and inspection of the spinal cord revealed that the mechanism of action for the slow group appeared to be ischemia of the spinal cord that extended several centimeters above and below the site of maximum distraction. In the fast-loss group, it appeared that gross structural damage, with some very localized ischemia, were the mechanisms of actions influencing the integrity of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between duration of spinal cord ischemia and postoperative neurologic deficits in animals.

Stagnara wake-up tests, blood flow measures, somatosensory evoked potentials (SEPs), and neurogenic-motor evoked potentials (NMEPs) were elicited from 20 hogs before and after spinal cord overdistraction at L3-L4. Overdistraction was maintained from 5 to 30 minutes after loss of NMEPs. Results suggest that the longer the duration of overdistraction the greater the likelihood of paraplegia. Blood flow measures indicated that reduced perfusion was greatest at the distraction site but extended proximally and distally. Finally, NMEPs were more sensitive to onset of overdistraction and a more valid indicator of paraplegia than SEPs. NMEPs should provide the surgeon with more time for initiation of intervention techniques than SEPs. Because NMEPs and SEPs provide information regarding different spinal cord tracts, the authors continue to use both methods for monitoring the functional integrity of the human spinal cord during corrective spine surgery.

Blood flow direction in the lumbar nerve root.

The effect of clipping on lumbar nerve root blood flow rates in the region of the nerve root canal was studied experimentally in the hog. Blood flow rate was measured using the hydrogen washout technique. When the entrance zone was clipped with a microvascular clip, blood flow rate of the nerve root was decreased by 37% in comparison with the initial control rate; clipping at the exit zone reduced blood flow rate by 69%. Blood flow direction in the lumbar nerve root within the nerve root canal was found to be predominantly proximal. The current data indicate that the more lateral the impingement of the nerve root occurs, the more ischemic changes are induced.

Effects of distraction on physiologic integrity of the spinal cord, spinal cord blood flow, and clinical status.

The authors determined the effects of distraction of the spine on physiologic integrity of the spinal cord using neurogenic motor evoked potentials (NMEPs), somatosensory evoked potentials (SEPs), spinal cord blood flow measurements, and clinical status in nine hogs. Spinal cord blood flow was measured after each level of distraction using the hydrogen washout technique. The results indicated that blood flow of at least 65% of baseline was required to maintain physiologic integrity of the spinal cord, and that a decrease of blood flow to 12% of baseline was associated with paraplegia. Neurogenic motor evoked potentials always correlated with the animal's postsurgical clinical status, whereas the SEP was falsely negative in one animal.

Magnetic stimulation of the spine to produce lower extremity EMG responses. Significance of coil position and the presence of bone.

STUDY DESIGN: Magnetic stimulation of the spinal cord in 14 pigs was performed, and compound muscle action potentials (CMAPs) were recorded from lower extremities before and after nerve root and spinal cord lesioning. OBJECTIVES: The authors determined whether magnetic stimulation of the spinal cord produced lower extremity CMAPs. SUMMARY OF BACKGROUND DATA: Previous studies indicated that the magnetic stimulation of the spinal cord would result in lower extremity CMAP if appropriate amounts of spinal bone were removed to expose the spinal cord. RESULTS: Our findings demonstrated that the presence of intervening bone did not affect the reliability or presence of lower extremity CMAPs. Additionally, magnetic stimulation did not result in spinal cord activation but produced activity in nerve roots lateral to nerve root foramen. Lesioning of the spinal cord and complete rhizotomies did not affect magnetically elicited CMAPs. CONCLUSIONS: Magnetic stimulation of the spinal canal does not result in activation of spinal cord motor tracts. Lower extremity CMAPs were elicited by stimulation of nerve roots lateral to nerve root foramen and not of the spinal cord. Magnetic stimulation of the spinal cord is not appropriate for monitoring spinal cord motor tract function.

The effect of nerve root lesioning on various somatosensory evoked potentials in the hog.

Somatosensory evoked potentials (SEPs) were recorded at the lumbar spine following stimulation of the tibial nerve (mixed-nerve SEP; MSEP), the sural nerve (specific nerve SEP; SSEP), and the skin corresponding to the L6 and S1 dermatomes (dermatomal field SEP; DSEP-L and DSEP-S) in the hog. To determine the sensitivity of these three SEPs to the single nerve root (S1 root) function, the effects of nerve roots lesioning were investigated. Cutting S1 nerve root reduced the peak-to-peak amplitude of MSEP by only 28% in comparison with baseline values. The relative amplitudes of SSEP, DSEP-L, and DSEP-S were decreased by 46%, 11% and 51%, respectively. When S1 nerve root was left intact and L5, L6, and S2 nerve roots were cut, the relative amplitudes of MSEP, SSEP, DSEP-L, and DSEP-S were decreased to 68%, 73%, 31%, and 74%, respectively. These results indicate that DSEP-S is as sensitive to the function of S1 nerve root as SSEP but the sensitivities of DSEP-S and SSEP are low in the hog. MSEP is shown unsuitable to monitor the single nerve root dysfunction.

Efficacy of multimodality spinal cord monitoring during surgery for neuromuscular scoliosis.

STUDY DESIGN: This study determined the relative efficacy of somatosensory-evoked potentials and motor-evoked potentials in monitoring spinal cord function during surgery for patients with idiopathic versus neuromuscular scoliosis. OBJECTIVES: To determine whether patients with idiopathic versus neuromuscular scoliosis demonstrate significantly different somatosensory-evoked potentials and motor-evoked potentials recorded during surgery. SUMMARY OF BACKGROUND DATA: Ashkenaze et al (1993) and others have reported that cortical somatosensory-evoked potentials are unreliable when used to monitor spinal cord function in patients with neuromuscular scoliosis. It was recommended that other neurophysiologic tests be used. METHODS: Somatosensory-evoked potentials and motor-evoked potentials were recorded from two groups of patients: those with idiopathic scoliosis and those with neuromuscular scoliosis. Somatosensory-evoked potentials were obtained before and during surgery. Motor-evoked potentials were obtained during surgery. Normal variability, as indicated from idiopathic scoliotic results, was compared with data obtained from patients with neuromuscular scoliosis. Motor-evoked potentials and somatosensory-evoked potentials were obtained sequentially during the duration of surgery. RESULTS: Single-channel cortical somatosensory-evoked potentials demonstrated a 27% positive rate, which was consistent with results (28%) from Ashkenaze et al. The use of multiple recording sites for the somatosensory-evoked potentials and the addition of motor-evoked potential procedures indicated that a reliable response could be obtained in more than 96% of the patients. It also was found that cortical somatosensory-evoked potentials were more affected by anesthetic agents when recorded from patients with neuromuscular scoliosis compared with patients with idiopathic scoliosis. CONCLUSIONS: Single-channel cortical somatosensory-evoked potentials demonstrated a high level of unreliability, which reduced their clinical effectiveness. However, by using multiple recording sites with the somatosensory-evoked potentials and by administering motor-evoked potential procedures, it was possible to monitor spinal cord function in neuromuscular patients and avoid postoperative neurologic deficits.

Innervation pattern of dorsal roots and their effects on the specificity of dermatomal somatosensory evoked potentials.

Dermatomal somatosensory evoked potentials are used to monitor individual nerve root function during degenerative spinal surgery. However, a less than 100% agreement between level(s) of dermatomal somatosensory evoked potentials abnormality and nerve root involvement has been reported. The purpose of this article was to determine the possible cause of this discrepancy. Results from humans suggest that variations in peripheral innervation patterns of the dorsal nerve roots are the main reason for dermatomal somatosensory evoked potentials discrepancy both for cervical and lumbar nerve roots. Because these variations cannot be controlled, the authors recommend that dermatomal somatosensory evoked potentials and additional neurophysiologic methods be used during degenerative surgeries to provide the surgeon with information about individual nerve root function. A patient profile for these methods was provided.

Sensitivity and specificity of somatosensory and neurogenic-motor evoked potentials in animals and humans.

The purpose of this study was to report the effects of spinal cord compression, ischemia, and distraction on clinical status, and somatosensory (SEP) and neurogenic-motor evoked potentials (NMEPs) in animals. The authors also reported their clinical experience with NMEPs elicited from humans undergoing surgery for spinal deformities. Results from the animal studies indicate that NMEPs are more sensitive and specific to the effects from spinal cord compression, ischemia, and distraction than SEPs. In every situation, NMEPs always correlated with the animal's post-surgical clinical status, while SEPs demonstrated an unacceptable false positive and false negative rate. In the 111 clinical cases in which NMEPs were administered, reliable NMEPs were easily elicited in more than 90% of the cases. In the remaining cases, no reliable NMEPs could be recorded because of procedural errors, which have been resolved. The results from this study suggest that the use of NMEPs should be considered as an adjunct to SEPs when monitoring spinal cord function during surgery.

Relationship between evoked potentials and clinical status in spinal cord ischemia.

STUDY DESIGN AND METHODS: Sciatic neurogenic motor-evoked potentials, spinal evoked potentials, and somatosensory-evoked potentials were recorded in 12 anesthetized dogs that had arterial ischemia of the lumbar cord produced by ligation of segmental arteries. The presence or absence of the above-mentioned potentials was compared with the clinical status of repeated wake-up tests. RESULTS: Although these results were complicated, sciatic neurogenic motor-evoked potential was more sensitive to the spinal cord ischemia and was a better predictor of clinical outcome than spinal evoked potential and somatosensory-evoked potential. However, the presence was not a guarantee of normal function. The initial morphologic change of these potentials secondary to ischemia consisted of a decrease in amplitude and in the number of peaks without a shift of latency. CONCLUSIONS: The present study suggests that the peripheral neurogenic motor-evoked potential is a better warning system for spinal cord ischemia and that its adoption may contribute to the prevention of cord ischemia during spinal surgery, whereas somatosensory-evoked potential and spinal evoked potential cannot be indices.

Relationship between evoked potentials and clinical status in spinal cord ischemia.

STUDY DESIGN: Sciatic neurogenic motor-evoked potentials (sciatic-NMEP), spinal-evoked potentials (spinal-EP), and somatosensory-evoked potentials (SEP) were recorded in the lumbar cord during progressive ligation of segmental arteries. Relationship between electrophysiologic assessment and clinical status was studied. OBJECTIVES: In 12 anesthetized dogs that had arterial ischemia of the lumbar cord produced by ligation of segmental arteries, the aforementioned evoked potentials were recorded, and their presence or absence was compared with the clinical status of repeated wake-up tests. SUMMARY OF BACKGROUND DATA: Both sciatic-NMEP loss and ligation level producing cord ischemia were not associated with severity of wake-up test. Sciatic-NMEPs were lost earlier than spinal-EP and SEPs after progressive ligation. The false-negative rate of sciatic-NMEP, SEP at high spine and at low spine was 12.5%, 20.8%, and 41.7%, respectively. The waveform morphology of potentials by cord ischemia decreased in amplitude and in the number of peaks without a shift of latency. METHODS: First, baseline NMEPs and SEPs were obtained, lumbar arteries were ligated, evoked potentials were recorded continuously, and wake-up test was administered. If sciatic-NMEPs were not lost, intercostal arteries were ligated, and potentials and clinical status were reassessed. RESULTS: Though these results were complicated, sciatic-NMEP was more sensitive to the spinal cord ischemia and a better predictor of clinical outcome than spinal-EP and SEP. However, the presence was not a guarantee of normal function. Somatosensory-evoked potentials are not a good predictor of clinical motor status. The initial morphologic change of these potentials secondary to ischemia consisted of a decrease in amplitude and in the number of peaks without a shift of latency. CONCLUSIONS: The peripheral-NMEP is a better warning system to spinal cord ischemia and its adoption may prevent cord ischemia during surgery, whereas SEP and spinal-EP can not be indicies.