Olmsted syndrome (OS) is a rare congenital disorder characterized by palmoplantar and periorificial keratoderma, alopecia in most cases, and severe itching. The genetic basis for OS remained unidentified. Using whole-exome sequencing of case-parents trios, we have identified a de novo missense mutation in TRPV3 that produces p.Gly573Ser in an individual with OS. Nucleotide sequencing of five additional affected individuals also revealed missense mutations in TRPV3 (which produced p.Gly573Ser in three cases and p.Gly573Cys and p.Trp692Gly in one case each). Encoding a transient receptor potential vanilloid-3 cation channel, TRPV3 is primarily expressed in the skin, hair follicles, brain, and spinal cord. In transfected HEK293 cells expressing TRPV3 mutants, much larger inward currents were recorded, probably because of the constitutive opening of the mutants. These gain-of-function mutations might lead to elevated apoptosis of keratinocytes and consequent skin hyperkeratosis in the affected individuals. Our findings suggest that TRPV3 plays essential roles in skin keratinization, hair growth, and possibly itching sensation in humans and selectively targeting TRPV3 could provide therapeutic potential for keratinization or itching-related skin disorders.

:  Melatonin has been reported to reduce infarct volumes induced by transient middle cerebral artery (MCA) occlusion. We examined whether melatonin could improve electrophysiological and neurobehavioral recoveries in rats after 72 hr of reperfusion following 1.5 hr of MCA occlusion. Melatonin (5 mg/kg) or vehicle was given intravenously at the commencement of reperfusion. Neurobehavioral outcome was serially examined, and somatosensory evoked potentials (SSEP) were recorded prior to ischemia and at 72 hr after the onset of reperfusion. Brain infarction was assessed upon killing. Before ischemia‐reperfusion, stable SSEP waveforms were consistently recorded after individual fore‐ or hindpaw stimulation. The amplitude between the first positive (P1) and the first negative (N1) peaks and the P1 latency did not differ significantly between controls and melatonin‐treated animals. At 72 hr of reperfusion, controls had severely depressant SSEPs recorded from ischemic fore‐ and hindpaw cortical fields, and the amplitudes decreased to 36 and 35% of baselines, respectively (P < 0.001). These animals also had transcallosal electrophysiological diaschisis in the SSEPs recorded at the contralateral hindpaw cortical field (P < 0.01). Relative to controls, melatonin‐treated animals not only had significantly improved amplitudes of the SSEPs recorded from both ischemic fore‐ and hindpaw cortical fields, by 33 and 37% of baselines, respectively (P < 0.001), but also exhibited diminished transcallosal electrophysiological diaschisis following ischemia‐reperfusion. In addition, melatonin improved sensory and motor neurobehavioral outcomes by 40 and 28%, respectively (P < 0.001), and reduced cortical and striatal infarct sizes by 32 and 40%, respectively (P < 0.05). Thus, delayed intravenous administration with melatonin both enhances electrophysiological and neurobehavioral recoveries and reduces cortical and striatal infarct sizes after cerebral ischemia and reperfusion injury.

Hyperkalemic periodic paralysis (HyperKPP) produces myotonia and attacks of muscle weakness triggered by rest after exercise or by K + ingestion. We introduced a missense substitution corresponding to a human familial HyperKPP mutation (Met1592Val) into the mouse gene encoding the skeletal muscle voltage-gated Na + channel Na V 1.4. Mice heterozygous for this mutation exhibited prominent myotonia at rest and muscle fibertype switching to a more oxidative phenotype compared with controls. Isolated mutant extensor digitorum longus muscles were abnormally sensitive to the Na + /K + pump inhibitor ouabain and exhibited age-dependent changes, including delayed relaxation and altered generation of tetanic force. Moreover, rapid and sustained weakness of isolated mutant muscles was induced when the extracellular K + concentration was increased from 4 mM to 10 mM, a level observed in the muscle interstitium of humans during exercise. Mutant muscle recovered from stimulation-induced fatigue more slowly than did control muscle, and the extent of recovery was decreased in the presence of high extracellular K + levels. These findings demonstrate that expression of the Met1592Val Na + channel in mouse muscle is sufficient to produce important features of HyperKPP, including myotonia, K + -sensitive paralysis, and susceptibility to delayed weakness during recovery from fatigue.

We have recently shown that melatonin decreases the late (24 hr) increase in blood–brain barrier (BBB) permeability and the risk of tissue plasminogen activator‐induced hemorrhagic transformation following ischemic stroke in mice. In the study, we further explored whether melatonin would reduce postischemic neurovascular oxidative/nitrosative damage and, therefore, improve preservation of the early increase in the BBB permeability at 4 hr after transient focal cerebral ischemia for 60 min in mice. Melatonin (5 mg/kg) or vehicle was given intraperitoneally at the beginning of reperfusion. Hydroethidine (HEt) in situ detection and immunohistochemistry for nitrotyrosine were used to evaluate postischemic accumulation in reactive oxygen and nitrogen species, respectively, in the ischemic neurovascular unit. BBB permeability was evaluated by spectrophotometric and microscopic quantitation of Evans Blue leakage. Relative to controls, melatonin‐treated animals not only had a significantly reduced superoxide accumulation in neurovascular units in boundary zones of infarction, by reducing 35% and 54% cytosolic oxidized HEt in intensity and cell‐expressing percentage, respectively (P < 0.001), but also exhibited a reduction in nitrotyrosine by 52% (P < 0.01). Additionally, melatonin‐treated animals had significantly reduced early postischemic disruption in the BBB permeability by 53% (P < 0.001). Thus, melatonin reduced postischemic oxidative/nitrosative damage to the ischemic neurovascular units and improved the preservation of BBB permeability at an early phase following transient focal cerebral ischemia in mice. The findings further highlight the ability of melatonin in anatomical and functional preservation for the ischemic neurovascular units and its relevant potential in the treatment of ischemic stroke.

Although adding oxaliplatin to fluorouracil and leucovorin in adjuvant chemotherapy for colon cancer may improve disease-free survival, grade 3-4 sensory neuropathy also increases. To determine whether oral N-acetylcysteine is neuroprotective against oxaliplatin-induced neuropathy, we did a pilot study. Fourteen stage III colon cancer patients with 4 or more regional lymph nodes metastasis (N2 disease) receiving adjuvant biweekly oxaliplatin (85 mg/m(2)) plus weekly fluorouracil boluses and low-dose leucovorin were randomized to oral N-acetylcysteine (1,200 mg) (arm A) or placebo (arm B). Clinical neurological and electrophysiological evaluations were performed at baseline and after 4, 8, and 12 treatment cycles. Treatment-related toxicity was evaluated based on National Cancer Institute (NCI) Criteria. After four cycles of chemotherapy, seven of nine patients in arm B and two of five in arm A experienced grade 1 sensory neuropathy. After eight cycles, five experienced sensory neuropathy (grade 2-4 toxicity) in arm B; none in arm A (p<0.05). After 12 cycles, grade 2-4 sensory neuropathy was observed in eight patients in arm B, one in arm A (p<0.05). There were no significant electrophysiological changes in arm A after 4, 8, or 12 cycles of chemotherapy. We concluded that oral N-acetylcysteine reduces the incidence of oxaliplatin-induced neuropathy in colon cancer patients receiving oxaliplatin-based adjuvant chemotherapy.

Melatonin protects against transient middle cerebral artery (MCA) occlusion and may be suited as an add-on therapy of tissue plasminogen activator (t-PA) thrombolysis. Herein, we examined whether melatonin would reduce postischemic increase in the blood-brain barrier (BBB) permeability and, therefore, attenuate the risk of hemorrhagic transformation after t-PA therapy in experimental stroke. Twelve mice were subjected to transient occlusion of the MCA for 1 hr, followed by 24 hr of reperfusion. Melatonin (5 mg/kg, i.p.) or vehicle was given at the beginning of reperfusion. BBB permeability was evaluated by quantitation of Evans Blue leakage. An additional 32 mice underwent photothrombotic occlusion of the distal MCA, and were administered vehicle or t-PA (10 mg/kg, i.v.), alone or in combination with melatonin (5 mg/kg, i.p.), at 6 hr postinsult. The animals were then killed after 24 hr for the determination of infarct and hemorrhage volumes. Relative to controls, melatonin-treated animals had significantly reduced BBB permeability (by 52%; P < 0.001). Additionally, we found that at 6 hr after photo-irradiation, either t-PA or melatonin, or a combined administration of t-PA plus melatonin, did not significantly affect brain infarction (P > 0.05), compared with controls. Mice treated with t-PA alone, however, had significantly increased hemorrhagic formation (P < 0.05), and the event was effectively reversed by co-treatment with melatonin (P < 0.05). Thus, melatonin improved postischemic preservation of the BBB permeability and a decreased risk of adverse hemorrhagic transformation after t-PA therapy for ischemic stroke. The findings further highlight melatonin's potential role in the field of thrombolytic treatment for ischemic stroke patients.

Pure hair and nail ectodermal dysplasia (PHNED) is a congenital condition characterized by hypotrichosis and nail dystrophy. Autosomal-recessive PHNED has previously been mapped to chromosomal region 12q12-q14.1, which contains the type II hair keratin and HOXC clusters. Hoxc13-null mice are known to develop hair and nail defects very similar to those seen in human PHNED. We performed whole-exome sequencing in a consanguineous Chinese family affected by PHNED and identified a homozygous nonsense mutation (c.390C>A [p.Tyr130(∗)]) in HOXC13 in all affected individuals. In an additional affected female from a consanguineous Afghan family, we found a 27.6 kb homozygous microdeletion involving the first exon of HOXC13. We examined HOXC13 expression in scalp specimen obtained from the index individual of the Chinese family and detected dramatically reduced mRNA levels in skin tissue and nearly absent protein staining in hair follicles, suggesting a mechanism of nonsense-mediated mRNA decay. We also observed markedly decreased expression of four HOXC13 target genes in the specimen. Taken together, our results demonstrate that loss-of-function mutations in HOXC13 cause autosomal-recessive PHNED and further highlight the importance of HOXC13 in hair and nail development.

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