Comparison of picosecond versus nanosecond Nd:YAG lasers for the removal of cosmetic tattoos in an animal model.

Cosmetic tattoos are difficult to remove, and their response to picosecond laser treatment has seldom been investigated. We compared the efficacy and adverse effects of picosecond versus Q-switched lasers for the removal of cosmetic tattoos. White, flesh-colored, and brown inks were irradiated using 532/1064 nm picosecond and Q-switched Nd:YAG lasers, and their absorption spectra before and after laser irradiation were analyzed. Nine rats were tattooed with all three inks. Each tattoo was divided into three sections and treated at 1064 nm with a picosecond laser or Q-switched laser, or left untreated, in four sessions at 1-month intervals. Skin biopsies were taken from treated and untreated sites. In vitro study showed the 1064 nm picosecond laser caused the least paradoxical color shift. In vivo study showed that all white tattoos achieved poor response scores, six flesh-colored tattoos achieved fair to good response scores, and seven brown tattoos achieved good to excellent response scores with the picosecond laser. The picosecond laser was superior to the Q-switched laser for removing flesh-colored tattoos (P < 0.05), but the effectiveness for white and brown tattoos was similar for both lasers. The degree of paradoxical darkening when removing the white and flesh-colored tattoos was significantly lower with the picosecond than that with the Q-switched laser (P < 0.01). Transmission electron microscopy showed that many tattoo ink particles had decreased in size after irradiations with both pulse durations. The 1064 nm picosecond Nd:YAG laser causes mild paradoxical darkening and might be more appropriate for removal of flesh-colored and brown cosmetic tattoos.

Mitochondrial UQCRC1 mutations cause autosomal dominant parkinsonism with polyneuropathy.

Parkinson's disease is a neurodegenerative disorder with a multifactorial aetiology. Nevertheless, the genetic predisposition in many families with multi-incidence disease remains unknown. This study aimed to identify novel genes that cause familial Parkinson's disease. Whole exome sequencing was performed in three affected members of the index family with a late-onset autosomal-dominant parkinsonism and polyneuropathy. We identified a novel heterozygous substitution c.941A>C (p.Tyr314Ser) in the mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) gene, which co-segregates with disease within the family. Additional analysis of 699 unrelated Parkinson's disease probands with autosomal-dominant Parkinson's disease and 1934 patients with sporadic Parkinson's disease revealed another two variants in UQCRC1 in the probands with familial Parkinson's disease, c.931A>C (p.Ile311Leu) and an allele with concomitant splicing mutation (c.70-1G>A) and a frameshift insertion (c.73_74insG, p.Ala25Glyfs*27). All substitutions were absent in 1077 controls and the Taiwan Biobank exome database from healthy participants (n = 1517 exomes). We then assayed the pathogenicity of the identified rare variants using CRISPR/Cas9-based knock-in human dopaminergic SH-SY5Y cell lines, Drosophila and mouse models. Mutant UQCRC1 expression leads to neurite degeneration and mitochondrial respiratory chain dysfunction in SH-SY5Y cells. UQCRC1 p.Tyr314Ser knock-in Drosophila and mouse models exhibit age-dependent locomotor defects, dopaminergic neuronal loss, peripheral neuropathy, impaired respiratory chain complex III activity and aberrant mitochondrial ultrastructures in nigral neurons. Furthermore, intraperitoneal injection of levodopa could significantly improve the motor dysfunction in UQCRC1 p.Tyr314Ser mutant knock-in mice. Taken together, our in vitro and in vivo studies support the functional pathogenicity of rare UQCRC1 variants in familial parkinsonism. Our findings expand an additional link of mitochondrial complex III dysfunction in Parkinson's disease.

Roles of corticosterone in formalin-induced conditioned place aversion in rats.

Glucocorticoid hormones have been shown to contribute to many cognitive functions, such as depressions, learning and memory, and abnormal glucocorticoid secretion results in functional changes in prefrontal cortex and amygdala. In the present study, we used the conditioned place aversion (CPA) paradigm to investigate the role of corticosterone (CORT) in the negative affective component of chemical somatic pain induced by intraplantar injection of formalin into male adult Long-Evan rats. Five percent of formalin produced acute biphasic nociceptive behaviors, including flinching and licking of hindpaw, and CPA. Intraplantar formalin induced CPA was abolished by bilateral adrenalectomy and the impairment of CPA can be restored by the CORT treatment. However, the adrenalectomy failed to affect the formalin-produced acute nociceptive behaviors. Therefore, data from the present study suggest that CORT secretion by the adrenal cortex may play a role in chemical somatic noxious stimuli-induced avoidance learning and aversive memory, but not sensory discrimination of noxious stimulation.

Activation of p38 mitogen-activated protein kinase in spinal microglia contributes to incision-induced mechanical allodynia.

BACKGROUND: Recent studies have implicated the activation of stress-activated mitogen-activated protein kinase (MAPK) p38 in spinal microglial cells for development of neuropathic and inflammatory pain. The aim of the present study was to investigate whether phosphorylation of p38 (p-p38) also mediates mechanical allodynia and thermal hyperalgesia induced by plantar incision. METHODS: After rats received a plantar incision surgery, mechanical allodynia and thermal hyperalgesia were determined by von Frey filaments and radiant heat, respectively, and the number of p-p38 immunoreactive cells in the dorsal horn was quantified to determine p38 activation at different time points after incision. The p38 inhibitor FR167653 was administered intrathecally 30 min before hind paw plantar incision to determine the role of p38 in postoperative pain. RESULTS: A significant increase in number of p-p38 immunoreactive cells was observed in the ipsilateral L4-5 spinal dorsal horn from 1 h to 3 days after the incision. p-p38 was found predominantly in microglia. However, microglial activation (assessed by OX-42 upregulation) was not evident until 3 days after plantar incision. Intrathecal pretreatment of FR167653 attenuated incision-induced mechanical allodynia from 1 h to day 2 and significantly reduced activation of p38 in the dorsal horn 1 day after plantar incision. However, FR167653 only inhibited heat hyperalgesia at an early time point. CONCLUSIONS: Plantar incision-induced mechanical allodynia can be prevented by the p38 inhibitor. Our results suggest that p38 activation in spinal microglia play a role in incision-induced mechanical allodynia in rats. Therefore, p38 inhibition may be useful in treating postsurgical pain.

Does the medial thalamus play a role in the negative affective component of visceral pain in rats?

Pain consists of sensory and negative affective components. Using a conditioned place aversion (CPA) paradigm, we investigated whether the medial thalamus (MT) played a role in the affective component of visceral pain induced by intraperitoneal injection of acetic acid into male Long-Evan rats. Acetic acid produced writhing response as well as CPA. The bilateral MT-lesions resulted in slight reduction of writhing response, but CPA was not affected. The results suggest that while MT may play a role in visceral nociception, it does not participate in the negative affective component of visceral pain.

Selective enhancement of tonic inhibition by increasing ambient GABA is insufficient to suppress excitotoxicity in hippocampal neurons.

Gamma-aminobutyric acid (GABA) activates synaptic GABA(A) receptors to generate inhibitory postsynaptic potentials. GABA also acts on extrasynaptic GABA(A) receptors, resulting in tonic inhibition. The physiological role of tonic inhibition, however, remains elusive. We explored the neurophysiological significance of tonic inhibition by testing whether selective activation of extrasynaptic GABA(A) receptors is sufficient to curb excitotoxicity. Tonic inhibition was selectively enhanced by increasing ambient GABA. In both acute hippocampal slices and cultured hippocampal neurons, boosting tonic inhibition alone is insufficient to withstand the hyper-excitability of hippocampal neurons induced by low-magnesium (Mg2+) baths. Furthermore, selective activation of extrasynaptic GABA(A) receptors resulted in no significant neuroprotective effects against glutamate or low-Mg2+-induced neuronal cell deaths. These data imply that under physiological conditions extrasynaptic GABA(A) receptors are optimally activated by ambient GABA and that a further increase in extracellular GABA concentration will not significantly enhance the effect of tonic inhibition on neuronal excitability.