Optimal blue light irradiation conditions for the treatment of acne vulgaris in a mouse model.

BACKGROUND: Although blue light is one of the therapeutic approaches used to treat acne vulgaris (AV), there is no consensus on its effectiveness. As a result, it is not recommended in the major acne vulgaris treatment guidelines. OBJECTIVE: The goal of this study was to look into the mechanism, safety, and efficacy of blue light therapy. We achieved this by examining the pathological response, inflammation, and depth of light penetration in a mouse model of cystic AV. METHODS: The aims of the study were addressed by exposing the mice to light with a wavelength of 415 nm under four different irradiation conditions. The exposure was done for five consecutive days followed by a no irradiation period of 72 h. RESULTS: Blue light treatment was most effective when irradiation was performed at 100 mW/cm2 for 20 min for five consecutive days. Inflammatory responses emerged 72 h after the final irradiation dose was administered. These responses were not associated with apoptosis as cleaved caspase-3 staining revealed no significant increases in apoptosis in the skin under any of the tested conditions. Blue light reached the superficial layer of the acne cyst at 5% of the total irradiation power and was attenuated by half for every 50 µm of progress through the cyst. CONCLUSION: In conclusion, blue light could control severe dermatologic inflammatory responses; therefore, it can be used to irradiate AV with high inflammation levels on a daily basis until improvement is observed. In addition, porphyrin, a metabolite of Cutibacterium acnes, and reactive oxygen species generated by the surrounding skin tissue may have essential roles in AV treatment.

Effects of CO2 on time-dependent changes in cardiorespiratory functions under sustained hypoxia.

Hypercapnia in addition to hypoxia affects the mammalian cardiorespiratory system and has been suggested to exert its effects on cardiorespiratory function by slightly different mechanisms to hypoxia. In the present study, we examined cardiorespiratory changes in urethane-anesthetized rats under hypocapnic (Hypo, 10% O2), isocapnic (Iso, 10% O2 and 4% CO2), and hypercapnic (Hyper, 10% O2 and 8% CO2) hypoxia for 2 h to clarify the effects of CO2 on sustained hypoxia-induced cardiorespiratory responses. Respiratory frequency increased the most in Hypo and tidal volume in Hyper. Minute ventilation, a product of respiratory frequency and tidal volume, increased the most in the latter group. Regarding cardiovascular variables during the hypoxic exposure period, heart rate and mean blood pressure both markedly decreased in Hypo. However, decreases in these parameters were small in Iso, and both increased over the pre-exposure level in Hyper. The present results suggest that CO2 interferes with the hypoxia-activated neural pathway via another pathway under sustained exposure to hypoxia.

Differences in the expression of catecholamine-synthesizing enzymes between vesicular monoamine transporter 1- and 2-immunoreactive glomus cells in the rat carotid body.

Vesicular monoamine transporters (VMAT) 1 and 2 are responsible for monoamine transportation into secretary vesicles and are tissue-specifically expressed in central and peripheral monoaminergic tissues, including the carotid body (CB). The aim of the present study was to examine the expression of catecholamine-synthesizing enzymes in VMAT1- and VMAT2-immunoreactive glomus cells in the rat CB using multiple immunolabeling. The expression of VMAT1 and VMAT2 mRNA in the CB was confirmed by RT-PCR. Immunohistochemistry revealed that VMAT1 immunoreactivity was predominant in glomus cells rather than VMAT2 immunoreactivity. Glomus cells with VMAT1 immunoreactivity exhibited weak/negative VMAT2 immunoreactivity, and vice versa. Immunoreactivities for VMAT1 and tyrosine hydroxylase, the rate-limiting enzyme for catecholamine biosynthesis, were co-localized in the same glomus cells and a positive correlation was confirmed between the two immunoreactivities (Spearman's coefficient = 0.82; p <  0.05). Although some glomus cells showed co-localization of VMAT2 and dopamine ß-hydroxylase immunoreactivity, the biosynthetic enzyme for noradrenaline, VMAT2 immunoreactivity appeared to be less associated with both catecholamine-synthesizing enzymes as indicated by a correlation analysis (TH: Spearman's coefficient = 0.38, DBH: Spearman's coefficient = 0.26). These results indicate that heterogeneity on functional role would exist among glomus cells in terms of VMAT isoform and catecholamine-synthesizing enzymes expression.

Time-dependent changes in cardiorespiratory functions of anesthetized rats exposed to sustained hypoxia.

Although cardiovascular responses may be altered by respiratory changes under prolonged hypoxia, the relationship between respiratory and cardiovascular changes remains unknown. The aim of the present study is to clarify cardiorespiratory changes in anesthetized rats during and after hypoxic conditions using simultaneous recordings of cardiorespiratory variables with 20-sec recording intervals. After air breathing for 20 min (pre-exposure period), rats were subjected to 10% O2 for 2 h (hypoxic exposure period) and then air for 30 min (recovery period). Minute ventilation (VE), respiratory frequency, tidal volume, arterial blood pressure (BP), and heart rate (HR) were continuously monitored during the experimental period. Just after hypoxic exposure, VE, BP, and HR exhibited an overshoot, undershoot, and overshoot followed by a decrease, respectively. During the remaining hypoxic exposure period, continuous high VE and low BP were observed, whereas HR re-increased. In the recovery period, VE, BP, and HR showed an undershoot, increase, and decrease followed by an increase, respectively. These results suggest that the continuation of enhanced VE and re-increased HR, probably, due to carotid body excitation and accompanying sympathetic activation, during the late period of hypoxic exposure are protective responses to avoid worsening hypoxemia and further circulatory insufficiencies under sustained hypoxia.

Age-related changes in immunoreactivity for dopamine ß-hydroxylase in carotid body glomus cells in spontaneously hypertensive rats.

The purpose of this study was to investigate immunoreactivity for dopamine ß-hydroxylase (DBH) and tyrosine hydroxylase (TH) in carotid body (CB) glomus cells in spontaneously hypertensive rats (SHR/Izm) at 4 (prehypertensive stage), 8 (early stage of developmental hypertension), 12 (later stage of developmental hypertension), and 16weeks of age (established hypertensive stage). Age-matched Wistar Kyoto rats (WKY/Izm) were used as controls. Staining properties for TH were similar between both strains at each age. Regarding DBH immunostaining, although some glomus cells showed intense DBH immunoreactivity at 4weeks of age, these cells were rarely observed at 8, 12, and 16weeks of age in WKY/Izm. In SHR/Izm, intense DBH immunoreactivity was observed in some glomus cells at 4weeks of age, these cells were also observed at 8 and 12weeks of age, and their number increased at 16weeks of age. An image analysis showed that the percentage of DBH-immunopositive glomus cells in WKY/Izm was approximately 30% at 4weeks of age and significantly decreased to approximately 10% at 8, 12, and 16weeks of age (p<0.05). This percentage in SHR/Izm was approximately 40% at each age. The gray scale intensity for DBH immunoreactivity in DBH-immunopositive glomus cells was similar in both strains at 4weeks of age, but became significantly lower in WKY/Izm and higher in SHR/Izm with increase in age (p<0.05). These results suggest that noradrenaline in glomus cells plays an important role in the regulation of neurotransmission between CB and afferent nerves during developmental hypertension.

Gender difference in the composition of fecal flora in laboratory mice, as detected by denaturing gradient gel electrophoresis (DGGE).

The difference between genders in the composition of mouse fecal flora was examined. A polymerase chain reaction followed by denaturing gradient gel electrophoresis (DGGE) were performed on the V6-V8 regions of bacterial 16S rDNA obtained from fecal samples at 0, 1, 2, 3, 4, and 8 weeks after the introduction of mice into the laboratory from a mouse farm. Cluster analysis and non-metric multidimensional scaling (NMDS) were then performed. Male and female mice were distributed on opposite sides of the origin of the plane in NMDS at weeks 0, 2, 3, and 8. These results suggest a gender difference in the composition of intestinal flora in mice.

Inhomogeneity of fecal flora in separately reared laboratory mice, as detected by denaturing gradient gel electrophoresis (DGGE).

Laboratory mice were divided into 2 groups and introduced to different rooms immediately after being transferred from a mouse farm. Polymerase chain reaction followed by denaturing gradient gel electrophoresis were performed on the V6-V8 regions of bacterial 16S rDNA obtained from fecal samples at 0, 1, 2, 3, 4 and 8 weeks after the introduction. Binary data were obtained from banding patterns, and Euclidean distances for each week were calculated and analyzed by cluster analysis and non-metric multidimensional scaling. Euclidean distances were significantly higher at weeks 1 and 2 than at week 0 in both groups, although the distances between the 2 groups were significantly higher after week 1 than week 0. The distances between the 2 groups were significantly higher than those within each group at weeks 4 and 8. Mice in the 2 groups formed clusters at weeks 2 and 3 respectively, and mice were divided into 2 clusters by their respective groups at weeks 4 and 8. Mice in the 2 groups were distributed on opposite sides of the origin on the 2-dimensional plane after week 2. These results suggest that mouse fecal flora changed characteristically, according to the local environment after introduction.

Examination of the applicability of a commercial human rotavirus antigen detection kit for use in laboratory rabbits.

The applicability of a commercial human rotavirus detection kit for the detection of lapine rotavirus in laboratory rabbits was examined. Rotavirus antigen positive samples determined by the kit were shown to include lapine rotavirus by reverse transcriptional polymerase chain reaction and restriction endonuclease analysis. The kit was confirmed to be adequate for the detection of lapine rotavirus by these results. The kit is suggested to be useful for the management of laboratory rabbits because of its ability to detect rotavirus antigen excretion which occurs in the early stage of the infection. It will contribute to minimizing the loss of rabbits in the event of an outbreak.