Mechanisms of increased hippocampal excitability in the Mashl+/- mouse model of Na+ /K+ -ATPase dysfunction.

OBJECTIVE: Na+ /K+ -ATPase dysfunction, primary (mutation) or secondary (energy crisis, neurodegenerative disease) increases neuronal excitability in the brain. To evaluate the mechanisms underlying such increased excitability we studied mice carrying the D801N mutation, the most common mutation causing human disease, specifically alternating hemiplegia of childhood (AHC) including epilepsy. Because the gene is expressed in all neurons, particularly γ-aminobutyric acid (GABA)ergic interneurons, we hypothesized that the pathophysiology would involve both pyramidal cells and interneurons and that fast-spiking interneurons, which have increased firing rates, would be most vulnerable. METHODS: We performed extracellular recordings, as well as whole-cell patch clamp recordings from pyramidal cells and interneurons, in the CA1 region on hippocampal slices. We also performed immunohistochemistry from hippocampal sections to count CA1 pyramidal cells as well as parvalbumin-positive interneurons. In addition, we performed video-electroencephalography (EEG) recordings from the dorsal hippocampal CA1 region. RESULTS: We observed that juvenile knock-in mice carrying the above mutation reproduce the human phenotype of AHC. We then demonstrated in the CA1 region of these mice the following findings as compared to wild type: (1) Increased number of spikes evoked by electrical stimulation of Schaffer collaterals; (2) equalization by bicuculline of the number of spikes induced by Schaffer collateral stimulation; (3) reduced miniature, spontaneous, and evoked inhibitory postsynaptic currents, but no change in excitatory postsynaptic currents; (4) robust action potential frequency adaptation in response to depolarizing current injection in CA1 fast-spiking interneurons; and (5) no change in the number of pyramidal cells, but reduced number of parvalbumin positive interneurons. SIGNIFICANCE: Our data indicate that, in our genetic model of Atp1α3 mutation, there is increased excitability and marked dysfunction in GABAergic inhibition. This supports the performance of further investigations to determine if selective expression of the mutation in GABAergic and or glutamatergic neurons is necessary and sufficient to result in the behavioral phenotype.

Motor function domains in alternating hemiplegia of childhood.

AIM: To characterize motor function profiles in alternating hemiplegia of childhood, and to investigate interrelationships between these domains and with age. METHOD: We studied a cohort of 23 patients (9 males, 14 females; mean age 9y 4mo, range 4mo-43y) who underwent standardized tests to assess gross motor, upper extremity motor control, motor speech, and dysphagia functions. RESULTS: Gross Motor Function Classification System (GMFCS), Gross Motor Function Measure-88 (GMFM-88), Manual Ability Classification System (MACS), and Revised Melbourne Assessment (MA2) scales manifested predominantly mild impairments; motor speech, moderate to severe; Modified Dysphagia Outcome and Severity Scale (M-DOSS), mild-to moderate deficits. GMFCS correlated with GMFM-88 scores (Pearson's correlation, p=0.002), MACS (p=0.038), and MA2 fluency (p=0.005) and accuracy (p=0.038) scores. GMFCS did not correlate with motor speech (p=0.399), MA2 dexterity (p=0.247), range of motion (p=0.063), or M-DOSS (p=0.856). Motor speech was more severely impaired than the GMFCS (p<0.013). There was no correlation between any of the assessment tools and age (p=0.210-0.798). INTERPRETATION: Our data establish a detailed profile of motor function in alternating hemiplegia of childhood, argue against the presence of worse motor function in older patients, identify tools helpful in evaluating this population, and identify oropharyngeal function as the more severely affected domain, suggesting that brain areas controlling this function are more affected than others.

Diagnosis and Treatment of Alternating Hemiplegia of Childhood.

OPINION STATEMENT: The diagnosis and treatment of patients with Alternating Hemiplegia of Childhood (AHC) and related disorders should be provided by a multidisciplinary team experienced with the spectrum of presentations of this disease, with its related disorders, with its complex and fluctuating manifestations, and with cutting edge advances occurring in the field. Involvement in research to advance the understanding of this disease and partnership with international collaborators and family organizations are also important. An example of such an approach is that of The Duke AHC and Related Disorders Multi-Disciplinary Clinic and Program, which, in partnership with the Cure AHC Foundation, has developed and applied this approach to patients seen since early 2013. The program provides comprehensive care and education directly to AHC patients and their families and collaborates with referring physicians on the care of patients with AHC whether evaluated at Duke clinics or not. It also is involved in clinical and basic research and in collaborations with other International AHC Research Consortium (IAHCRC) partners. The clinic is staffed with physicians and experts from Neurology, Cardiology, Child Behavioral Health, Medical Genetics, Neurodevelopment, Neuropsychology, Nursing, Physical and Occupational Therapies, Psychiatry, Sleep Medicine, and Speech/Language Pathology. Patients are seen either for full comprehensive evaluations that last several days or for targeted evaluations with one or few appointments.

Plasma cytokine analysis in patients with advanced extremity melanoma undergoing isolated limb infusion.

BACKGROUND: Preprocedure clinical and pathologic factors have failed to consistently differentiate complete response (CR) from progressive disease (PD) in patients after isolated limb infusion (ILI) with melphalan for unresectable in-transit extremity melanoma. METHODS: Multiplex immunobead assay technology (Milliplex MAP Human Cytokine/Chemokine Magnetic Bead Panel, Millipore Corp., Billerica, MA; and Magpix analytical test instrument, Luminex Corp., Austin, TX) was performed on pre-ILI plasma to determine concentrations of selected cytokines (MIP-1α, IL-1Rα, IP-10, IL-1ß, IL-1α, MCP-1, IL-6, IL-17, EGF, IL-12p40, VEGF, GM-CSF, and MIP-1ß) on a subset of patients (n = 180) who experienced CR (n = 23) or PD (n = 24) after ILI. Plasma from normal donors (n = 12) was also evaluated. RESULTS: Of 180 ILIs performed, 28 % (95 % confidence interval 22-35, n = 50) experienced a CR, 14 % (n = 25) experienced a partial response, 11 % (n = 21) had stable disease, 34 % (n = 61) had PD, and 13 % (n = 23) were not evaluable for response. Tumor characteristics and pharmacokinetics appeared similar between CR (n = 23) and PD (n = 24) patients who underwent cytokine analysis. Although there were no differences in cytokine levels between CR and PD patients, there were differences between the melanoma patients and controls. MIP-1α, IL-1Rα, IL-1ß, IL-1α, IL-17, EGF, IL-12p40, VEGF, GM-CSF, and MIP-1ß were significantly higher in normal controls compared to melanoma patients, while IP-10 was lower (p < 0.001) in controls compared to melanoma patients. CONCLUSIONS: Patients with unresectable in-transit melanoma appear to have markedly decreased levels of immune activating cytokines compared to normal healthy controls. This further supports a potential role for immune-targeted therapies and immune monitoring in patients with regionally advanced melanoma.

A multi-institution experience comparing the clinical and physiologic differences between upper extremity and lower extremity melphalan-based isolated limb infusion.

BACKGROUND: Although studies of melphalan-based isolated limb infusion (ILI) combine data from upper extremity (UE) treatments with those from lower extremity (LE) treatments, differences between the 2 may be clinically important. METHODS: Candidates for UE ILI (n = 51) and LE ILI (n = 192) were identified from prospective databases at 2 institutions. The Response Evaluation Criteria in Solid Tumors and Wieberdink toxicity scale were used as appropriate. RESULTS: The following patients had indications for UE ILI: melanoma, 36 of 47 patients (77%); sarcoma, 5 of 47 patients (11%); Merkel cell sarcoma, 3 of 47 patients (6%), and squamous cell carcinoma, 3 of 47 patients (6%). The patients who underwent UE ILI, as expected, had lower limb volumes (mean, 2.5 L vs 8.6 L; P < .001) and lower mean melphalan doses (20.7 mg vs 49.5 mg; P < .001). On perfusate blood gas analysis, the mean base excess at 30 minutes (-13.9 vs -9.1; P < .001) and the mean pH at 30 minutes (7.06 vs 7.15; P < .001) were lower for UE procedures than for LE procedures, although the mean ischemic time was longer in LE procedures (67.2 minutes) than in UE procedures (61.6 minutes; P = .03). The rate of regional toxicity grade ≥3 for UE ILI was 7% compared with 24% (P = .005) for LE ILI. There was no difference in the complete response rate for melanoma UE procedures (28%; 95% confidence interval, 16%-44%) compared with LE ILI procedures (32%; 95% confidence interval, 25%-39%). CONCLUSIONS: ILI for UE disease was associated with similar complete response rates but lower toxicity than ILI for LE disease and with different physiologic sequelae despite comparable methods. The UE appears relatively resistant to toxic effects of melphalan-based ILI as currently performed, which suggests a potential for further optimization of drug dosing for UE ILI.