The influence of morphological distribution of melanin on parameter selection in laser thermotherapy for vascular skin diseases.

Port wine stains (PWSs) are congenital vascular malformations that progressively darken and thicken with age. Currently, laser therapy is the most effective way in clinical management of PWS. It is known that skin pigmentation (melanin content) affects the radiant exposure that can be safely applied to treat PWS. However, the effect of melanin distribution in the epidermis on the maximum safe radiant exposure has not been studied previously. In this study, 10 different morphological distributions of melanin were proposed according to the formation and migration characteristics of melanin, and the two-scale heat transfer model was employed to investigate the influence of melanin distribution on the threshold radiant exposure of epidermis and blood vessels. The results show that melanin distributions do have a strong effect on laser parameter selection. When uniform melanin distribution is assumed, the threshold radiant exposure to damage a typical PWS blood vessel (50 µm diameter) is 8.62 J/cm2 lower than that to injure epidermis. The optimal pulse duration is 1-5 ms for a typical PWS blood vessel of 50 µm when melanin distribution is taken into consideration. PWS blood vessels covered by non-uniformly distributed melanin are more likely to have poor response to laser treatment.

Effects of diets with different energy and bile acids levels on growth performance and lipid metabolism in broilers.

This experiment was conducted to evaluate the effects of bile acids (BAs) on the growth performance and lipid metabolism of broilers fed with different energy level diets. 480 one-day-old Arbor Acres broilers (45.01 ± 0.26 g) were allotted to a 2 × 2 factorial design with 2 levels of energy (basal or high-energy level) and 2 levels of BAs (with or without BAs supplementation), resulting in 4 groups of 8 replicates; the experiment lasted 42 d. High-energy diets decreased the feed/gain ratio (F/G) from 1 to 21 d (P < 0.05), and increased the liver index and abdominal fat percentage at 42 d (P < 0.05). The serum total triglyceride (TG) and high-density lipoprotein cholesterol at 42 d were increased by high-energy diets (P < 0.05), while the hepatic lipoprotein lipase (LPL) activity at 21 and 42 d was decreased (P < 0.05). BAs supplementation increased the body weight at 21 d and decreased the F/G during entire period (P < 0.05), as well as improved the carcass quality reflected by decreased abdominal fat percentage at 42 d and increased breast muscle percentage at 21 and 42 d (P < 0.05). The serum TG at 21 and 42 d were decreased by BAs (P < 0.05), and the hepatic LPL activity at 42 d was increased (P < 0.05). In addition, high-energy diets increased the expression of sterol regulatory element binding transcription factor 1, acetyl-CoA carboxylase, and fatty acid synthase (P < 0.05), while BAs diets decreased these genes expression (P < 0.05). Moreover, BAs supplementation also increased the expression of carnitine palmitoyltransferase 1 (P < 0.05), which was increased in high-energy groups (P < 0.05). In conclusion, BAs supplementation could increase growth performance, elevate carcass quality, and improve lipid metabolism in broilers.

Effects of dietary l-methionine supplementation on the growth performance, carcass characteristics, meat quality, and muscular antioxidant capacity and myogenic gene expression in low birth weight pigs.

The aim of the present study was to investigate the effects of dietary Met supplementation on the growth performance, carcass characteristics, meat quality, and muscular antioxidant capacity and myogenic gene expression in low birth weight (LBW) pigs. Thirty normal birth weight (NBW) and 60 LBW female piglets were selected at birth. In each litter, after weaning, 1 of the LBW piglets (LBW-CON group) and 1 of the NBW piglets (NBW-CON group) were fed the basal diets and 1 LBW littermate was fed the basal diet supplemented with Met (LBW-MET group). Thus, all pigs were distributed into groups of 3 treatments × 6 replicates (pens) × 5 piglets per replicate up to 180 d of age. Compared with NBW-CON pigs, LBW-CON pigs had decreased ADG ( = 0.004) and ADFI ( < 0.001) during the postweaning period and greater backfat thickness ( = 0.015) at slaughter. In addition, LBW-CON pigs exhibited compromised meat quality, as evidenced by a greater drip loss at 24 h postmortem( = 0.037) and a lower pH at 45 min postmortem ntents of malondialdehyde (MDA; = 0.046) and protein carbonyl ( = 0.028) in the LM. The LBW pigs fed the Met-supplemented diets had a greater amount of reduced glutathione (GSH; = 0.009) but a lower level of MDA ( = 0.015) in the LM compared with the LBW-CON pigs. Methionine supplementation increased the pH at 24 h postmortem (pH) value ( = 0.004) but reduced the drip loss at both 24 ( = 0.016) and 48 h ( = 0.005) postmortem of LBW-MET pigs in comparison with the LBW-CON pigs. The Met-supplemented diets increased the -adenosyl-methionine content ( = 0.006), DNA methyltransferase activity ( = 0.007), and CpG methylation levels of the sites +27 ( = 0.008) and +160 ( = 0.009) of myostatin (MSTN) exon 1 but decreased the mRNA expression of MSTN ( = 0.011) in the LM of the LBW-MET group compared with the LM of the LBW-CON group. Additionally, when compared with the LBW-CON group, the area of LM ( = 0.037) was significantly increased in the LBW-MET group, in parallel with the upregulated mRNA abundance of myogenin ( = 0.025), myocyte enhancer factor 2A ( = 0.036), and myocyte enhancer factor 2D ( = 0.015). In conclusion, Met supplementation increases pH and decreases drip loss in the LM of LBW-MET pigs, along with a greater GSH content but a lower MDA accumulation. Also, the LBW-MET pigs showed a greater LM area, which may be associated with the improved expression of myogenic genes.

Experimental study on the vascular thermal response to visible laser pulses.

Port-wine stains (PWSs) are congenital vascular malformations that progressively darken and thicken with age, and laser therapy is the most effective in clinical practice. Using dorsal skin chamber (DSC), this study evaluated thermal response of blood vessel to a 595-nm pulsed dye laser (PDL) with controlled energy doses and pulse durations. Totally, 32 vessels (30∼300 µm in diameter) are selected from the dorsal skin of the mouse to match those in port-wine stain. The experimental results showed that the thermal response of the blood vessels to laser irradiation can be recognized as coagulation, constriction with diameter decrease, disappearance (complete constriction), hemorrhage, and collagen damage in the order of increasing laser radiant exposure. Blood vessels with small diameter would response poorly and survive from the laser heating because their thermal relaxation time is much shorter than the pulse duration. The optimalradiant exposure is from 10 to 12 J/cm(2) under 6 ms pulse duration without considering the epidermal light absorption. Numerical simulations were also conducted using a 1,000-µm deep Sprague-Dawley (SD) mouse skinfold. The light transportation and heat diffusion in dorsal skin were simulated with the Monte Carlo method and heat transfer equation, while the blood vessel photocoagulation was evaluated by Arrhenius-type kinetic integral. Both experimental observation and numerical simulation supported that hemorrhage is the dominant thermal response, which occurs due to preferential heating of the superior parts of large blood vessels. In clinical practice for 595 nm PDL, the consequent purpura caused by hemorrhage can be used as a treatment end point.