Melanosomes are transferred from melanocytes to keratinocytes through the processes of packaging, release, uptake, and dispersion

Recent studies have described the role of shedding vesicles as physiological conveyers of intracellular components between neighboring cells. Here we report that melanosomes are one example of shedding vesicle cargo, but are processed by a previously unreported mechanism. Pigment globules were observed to be connected to the filopodia of melanocyte dendrites, which have previously been shown to be conduits for melanosomes. Pigment globules containing multiple melanosomes were released from various areas of the dendrites of normal human melanocytes derived from darkly pigmented skin. The globules were then captured by the microvilli of normal human keratinocytes, also derived from darkly pigmented skin, which incorporated them in a protease-activated receptor-2 (PAR-2)-dependent manner. After the pigment globules were ingested by the keratinocytes, the membrane that surrounded each melanosome cluster was gradually degraded, and the individual melanosomes then spread into the cytosol and were distributed primarily in the perinuclear area of each keratinocyte. These results suggest a melanosome transfer pathway wherein melanosomes are transferred from melanocytes to keratinocytes via the shedding vesicle system. This packaging system generates pigment globules containing multiple melanosomes in a unique manner.     

FUS/TLS-immunoreactive neuronal and glial cell inclusions increase with disease duration in familial amyotrophic lateral sclerosis with an R521C FUS/TLS mutation

Basophilic inclusions (BIs) are pathological features of a subset of frontotemporal lobar degeneration disorders, including sporadic amyotrophic lateral sclerosis (ALS) and familial ALS (FALS). Mutations in the fused in sarcoma/translocated in liposarcoma (FUS/TLS) gene have recently been identified as a cause of FALS. The FUS/TLS-immunoreactive inclusions are consistently found in cases of frontotemporal lobar degeneration with BIs; however, the association between ALS cases with BIs and FUS/TLS accumulation is not well understood. We used immunohistochemistry to analyze 3 autopsy cases of FALS with the FUS/TLS mutation and with BIs using anti-FUS/TLS antibodies. The disease durations were 1, 3, and 9 years. As the disease duration becomes longer, there were broader distributions of neuronal and glial FUS/TLS-immunoreactive inclusions. As early as 1 year after the onset, BIs, neuronal cytoplasmic inclusions and glial cytoplasmic inclusions were found in the substantia nigra in addition to the anterior horn of the spinal cord. Glial cytoplasmic inclusions are found earlier and in a wider distribution than neuronal cytoplasmic inclusions. The distribution of FUS/TLS-immunoreactive inclusions in FUS/TLS-mutated FALS with BIs was broader than that of BIs alone, suggesting that the pathogenetic mechanism may have originated from the FUS/TLS proteinopathy.     

Differential diagnosis of true and pseudo-bilateral benign positional nystagmus

CONCLUSIONS: Two patients showing two rotational axes of their positional nystagmus had canalolithiasis in bilateral posterior semicircular canals (PSCCs), leading to the diagnosis of true bilateral benign paroxysmal positional nystagmus (P-BPPN). Another 18 patients had a single rotation axis of their positional nystagmus with short time constant (TC) on one side and long TC on the other. Since canalolithiasis in the uppermost PSCC may be transient cupulolithiasis, evoking positional nystagmus with long TC, the diagnosis of the latter patients should be pseudo-bilateral P-BPPN. OBJECTIVE: To differentiate the true bilateral posterior canal type of P-BPPN from pseudo-bilateral P-BPPN. PATIENTS AND METHODS: The rotational axis and TC of positional nystagmus were three-dimensionally analyzed in 20 patients showing geotropic torsional nystagmus on the left and right Dix-Hallpike (D-H) maneuvers. RESULTS: Two patients showed two rotational axes of their positional nystagmus, which were perpendicular to the plane of the PSCCs. There were no differences in TCs of their positional nystagmus between bilateral D-Hs. Another 18 patients showed a single rotational axis of their positional nystagmus, which was perpendicular to the plane of either the left or right PSCC. TCs of their positional nystagmus were short on one side and long on the other.     

Enhanced scratching evoked by PAR-2 agonist and 5-HT but not histamine in a mouse model of chronic dry skin itch

Chronic itch is a symptom of many skin conditions and systemic disease, and it has been hypothesized that the chronic itch may result from sensitization of itch-signaling pathways. We induced experimental chronic dry skin on the rostral back of mice, and observed a significant increase in spontaneous hindlimb scratches directed to the dry skin. Spontaneous scratching was significantly attenuated by a PAR-2 antibody and 5-HT2A receptor antagonist, indicating activation of these receptors by endogenous mediators released under dry skin conditions. We also observed a significant increase in the number of scratch bouts evoked by acute intradermal injections of a protease-activated receptor (PAR)-2 agonist and serotonin (5-HT), but not histamine. We additionally investigated if pruritogen-evoked activity of dorsal root ganglion (DRG) neurons is enhanced in this model. DRG cells from dry skin mice exhibited significantly larger responses to the PAR-2 agonist and 5-HT, but not histamine. Spontaneous scratching may reflect ongoing itch, and enhanced pruritogen-evoked scratching may represent hyperknesis (enhanced itch), both potentially due to sensitization of itch-signaling neurons. The correspondence between enhanced behavioral scratching and DRG cell responses suggest that peripheral pruriceptors that respond to proteases and 5-HT, but not histamine, may be sensitized in dry skin itch.     

Clinical significance of measurement of urinary leukotriene E4 in asthmatic patients without attack]

To evaluate clinical significance of measurement of urinary leukotriene E4 (LTE4) in asthmatic patients without attack, we measured urinary LTE4 in 68 asthmatic patients without attack and investigated its correlation with severity of asthma, % FEV1, bronchial hyperresponsiveness and peripheral eosinophil counts. Values of urinary LTE4 were significantly higher in the asthmatic patients (113.6 +/- 9.7 pg/mg.cr) than in healthy control subjects (67.8 +/- 4.7, n = 31), and the level of urinary LTE4 was in proportion to the severity of disease. Urinary LTE4 showed significant negative correlation with % FEV1 in atopic patients (Rs = -0.43, p = 0.025, n = 28), which was not recognized in non-atopic patients. Urinary LTE4 showed no significant correlation with bronchial hyperresponsiveness and peripheral eosinophil counts. Our findings suggested that basal LTE4 in urine reflected chronic airway inflammation of asthma.     

The Estimation of Cardiac Function from the Rotary Blood Pump

The rotary blood pump is implanted as a bridge to cardiac transplantation. Mechanical, histological, and biochemical improvements have been described in patients after implantation of left ventricular assist devices (LVADs). Thus, the rotary blood pump might be used as a bridge to recovery of myocardial function. However, unlike a pulsatile pump, the rotary blood pump cannot be stopped to estimate cardiac function: if the rotary blood pump stops, backflow will occur. In this study, a new method that can estimate cardiac function without pump stop was examined. Six pigs were the subjects of this acute study. The pump was implanted as an LVAD: the inlet cannula was inserted into the left ventricle, and the outlet cannula was inserted into the ascending aorta. The motor speed was regulated at a pump flow rate of 0 L/min at diastolic phase. Then, the relationship between the dp/dt of left ventricular pressure and external stroke work of actuator was examined. This method was studied at normal, hyperdynamic, and heart-failure conditions. There was a high positive correlation between the dp/dt of left ventricular pressure and external stroke work of actuator. This method is useful and simple to estimate cardiac function without pump stop.